--- old/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp 2015-05-13 13:55:35.764002150 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,6575 +0,0 @@ -/* - * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. - * - * This code is free software; you can redistribute it and/or modify it - * under the terms of the GNU General Public License version 2 only, as - * published by the Free Software Foundation. - * - * This code is distributed in the hope that it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License - * version 2 for more details (a copy is included in the LICENSE file that - * accompanied this code). - * - * You should have received a copy of the GNU General Public License version - * 2 along with this work; if not, write to the Free Software Foundation, - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. - * - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA - * or visit www.oracle.com if you need additional information or have any - * questions. - * - */ - -#include "precompiled.hpp" -#include "classfile/metadataOnStackMark.hpp" -#include "classfile/stringTable.hpp" -#include "code/codeCache.hpp" -#include "code/icBuffer.hpp" -#include "gc_implementation/g1/bufferingOopClosure.hpp" -#include "gc_implementation/g1/concurrentG1Refine.hpp" -#include "gc_implementation/g1/concurrentG1RefineThread.hpp" -#include "gc_implementation/g1/concurrentMarkThread.inline.hpp" -#include "gc_implementation/g1/g1AllocRegion.inline.hpp" -#include "gc_implementation/g1/g1CollectedHeap.inline.hpp" -#include "gc_implementation/g1/g1CollectorPolicy.hpp" -#include "gc_implementation/g1/g1ErgoVerbose.hpp" -#include "gc_implementation/g1/g1EvacFailure.hpp" -#include "gc_implementation/g1/g1GCPhaseTimes.hpp" -#include "gc_implementation/g1/g1Log.hpp" -#include "gc_implementation/g1/g1MarkSweep.hpp" -#include "gc_implementation/g1/g1OopClosures.inline.hpp" -#include "gc_implementation/g1/g1ParScanThreadState.inline.hpp" -#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" -#include "gc_implementation/g1/g1RemSet.inline.hpp" -#include "gc_implementation/g1/g1RootProcessor.hpp" -#include "gc_implementation/g1/g1StringDedup.hpp" -#include "gc_implementation/g1/g1YCTypes.hpp" -#include "gc_implementation/g1/heapRegion.inline.hpp" -#include "gc_implementation/g1/heapRegionRemSet.hpp" -#include "gc_implementation/g1/heapRegionSet.inline.hpp" -#include "gc_implementation/g1/vm_operations_g1.hpp" -#include "gc_implementation/shared/gcHeapSummary.hpp" -#include "gc_implementation/shared/gcTimer.hpp" -#include "gc_implementation/shared/gcTrace.hpp" -#include "gc_implementation/shared/gcTraceTime.hpp" -#include "gc_implementation/shared/isGCActiveMark.hpp" -#include "memory/allocation.hpp" -#include "memory/gcLocker.inline.hpp" -#include "memory/generationSpec.hpp" -#include "memory/iterator.hpp" -#include "memory/referenceProcessor.hpp" -#include "oops/oop.inline.hpp" -#include "runtime/atomic.inline.hpp" -#include "runtime/orderAccess.inline.hpp" -#include "runtime/vmThread.hpp" -#include "utilities/globalDefinitions.hpp" -#include "utilities/stack.inline.hpp" -#include "utilities/taskqueue.inline.hpp" - -size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; - -// turn it on so that the contents of the young list (scan-only / -// to-be-collected) are printed at "strategic" points before / during -// / after the collection --- this is useful for debugging -#define YOUNG_LIST_VERBOSE 0 -// CURRENT STATUS -// This file is under construction. Search for "FIXME". - -// INVARIANTS/NOTES -// -// All allocation activity covered by the G1CollectedHeap interface is -// serialized by acquiring the HeapLock. This happens in mem_allocate -// and allocate_new_tlab, which are the "entry" points to the -// allocation code from the rest of the JVM. (Note that this does not -// apply to TLAB allocation, which is not part of this interface: it -// is done by clients of this interface.) - -// Local to this file. - -class RefineCardTableEntryClosure: public CardTableEntryClosure { - bool _concurrent; -public: - RefineCardTableEntryClosure() : _concurrent(true) { } - - bool do_card_ptr(jbyte* card_ptr, uint worker_i) { - bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); - // This path is executed by the concurrent refine or mutator threads, - // concurrently, and so we do not care if card_ptr contains references - // that point into the collection set. - assert(!oops_into_cset, "should be"); - - if (_concurrent && SuspendibleThreadSet::should_yield()) { - // Caller will actually yield. - return false; - } - // Otherwise, we finished successfully; return true. - return true; - } - - void set_concurrent(bool b) { _concurrent = b; } -}; - - -class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { - private: - size_t _num_processed; - - public: - RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } - - bool do_card_ptr(jbyte* card_ptr, uint worker_i) { - *card_ptr = CardTableModRefBS::dirty_card_val(); - _num_processed++; - return true; - } - - size_t num_processed() const { return _num_processed; } -}; - -YoungList::YoungList(G1CollectedHeap* g1h) : - _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), - _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { - guarantee(check_list_empty(false), "just making sure..."); -} - -void YoungList::push_region(HeapRegion *hr) { - assert(!hr->is_young(), "should not already be young"); - assert(hr->get_next_young_region() == NULL, "cause it should!"); - - hr->set_next_young_region(_head); - _head = hr; - - _g1h->g1_policy()->set_region_eden(hr, (int) _length); - ++_length; -} - -void YoungList::add_survivor_region(HeapRegion* hr) { - assert(hr->is_survivor(), "should be flagged as survivor region"); - assert(hr->get_next_young_region() == NULL, "cause it should!"); - - hr->set_next_young_region(_survivor_head); - if (_survivor_head == NULL) { - _survivor_tail = hr; - } - _survivor_head = hr; - ++_survivor_length; -} - -void YoungList::empty_list(HeapRegion* list) { - while (list != NULL) { - HeapRegion* next = list->get_next_young_region(); - list->set_next_young_region(NULL); - list->uninstall_surv_rate_group(); - // This is called before a Full GC and all the non-empty / - // non-humongous regions at the end of the Full GC will end up as - // old anyway. - list->set_old(); - list = next; - } -} - -void YoungList::empty_list() { - assert(check_list_well_formed(), "young list should be well formed"); - - empty_list(_head); - _head = NULL; - _length = 0; - - empty_list(_survivor_head); - _survivor_head = NULL; - _survivor_tail = NULL; - _survivor_length = 0; - - _last_sampled_rs_lengths = 0; - - assert(check_list_empty(false), "just making sure..."); -} - -bool YoungList::check_list_well_formed() { - bool ret = true; - - uint length = 0; - HeapRegion* curr = _head; - HeapRegion* last = NULL; - while (curr != NULL) { - if (!curr->is_young()) { - gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " - "incorrectly tagged (y: %d, surv: %d)", - p2i(curr->bottom()), p2i(curr->end()), - curr->is_young(), curr->is_survivor()); - ret = false; - } - ++length; - last = curr; - curr = curr->get_next_young_region(); - } - ret = ret && (length == _length); - - if (!ret) { - gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); - gclog_or_tty->print_cr("### list has %u entries, _length is %u", - length, _length); - } - - return ret; -} - -bool YoungList::check_list_empty(bool check_sample) { - bool ret = true; - - if (_length != 0) { - gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", - _length); - ret = false; - } - if (check_sample && _last_sampled_rs_lengths != 0) { - gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); - ret = false; - } - if (_head != NULL) { - gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); - ret = false; - } - if (!ret) { - gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); - } - - return ret; -} - -void -YoungList::rs_length_sampling_init() { - _sampled_rs_lengths = 0; - _curr = _head; -} - -bool -YoungList::rs_length_sampling_more() { - return _curr != NULL; -} - -void -YoungList::rs_length_sampling_next() { - assert( _curr != NULL, "invariant" ); - size_t rs_length = _curr->rem_set()->occupied(); - - _sampled_rs_lengths += rs_length; - - // The current region may not yet have been added to the - // incremental collection set (it gets added when it is - // retired as the current allocation region). - if (_curr->in_collection_set()) { - // Update the collection set policy information for this region - _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); - } - - _curr = _curr->get_next_young_region(); - if (_curr == NULL) { - _last_sampled_rs_lengths = _sampled_rs_lengths; - // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); - } -} - -void -YoungList::reset_auxilary_lists() { - guarantee( is_empty(), "young list should be empty" ); - assert(check_list_well_formed(), "young list should be well formed"); - - // Add survivor regions to SurvRateGroup. - _g1h->g1_policy()->note_start_adding_survivor_regions(); - _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); - - int young_index_in_cset = 0; - for (HeapRegion* curr = _survivor_head; - curr != NULL; - curr = curr->get_next_young_region()) { - _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); - - // The region is a non-empty survivor so let's add it to - // the incremental collection set for the next evacuation - // pause. - _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); - young_index_in_cset += 1; - } - assert((uint) young_index_in_cset == _survivor_length, "post-condition"); - _g1h->g1_policy()->note_stop_adding_survivor_regions(); - - _head = _survivor_head; - _length = _survivor_length; - if (_survivor_head != NULL) { - assert(_survivor_tail != NULL, "cause it shouldn't be"); - assert(_survivor_length > 0, "invariant"); - _survivor_tail->set_next_young_region(NULL); - } - - // Don't clear the survivor list handles until the start of - // the next evacuation pause - we need it in order to re-tag - // the survivor regions from this evacuation pause as 'young' - // at the start of the next. - - _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); - - assert(check_list_well_formed(), "young list should be well formed"); -} - -void YoungList::print() { - HeapRegion* lists[] = {_head, _survivor_head}; - const char* names[] = {"YOUNG", "SURVIVOR"}; - - for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { - gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); - HeapRegion *curr = lists[list]; - if (curr == NULL) - gclog_or_tty->print_cr(" empty"); - while (curr != NULL) { - gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", - HR_FORMAT_PARAMS(curr), - p2i(curr->prev_top_at_mark_start()), - p2i(curr->next_top_at_mark_start()), - curr->age_in_surv_rate_group_cond()); - curr = curr->get_next_young_region(); - } - } - - gclog_or_tty->cr(); -} - -void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { - HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); -} - -void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { - // The from card cache is not the memory that is actually committed. So we cannot - // take advantage of the zero_filled parameter. - reset_from_card_cache(start_idx, num_regions); -} - -void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) -{ - // Claim the right to put the region on the dirty cards region list - // by installing a self pointer. - HeapRegion* next = hr->get_next_dirty_cards_region(); - if (next == NULL) { - HeapRegion* res = (HeapRegion*) - Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), - NULL); - if (res == NULL) { - HeapRegion* head; - do { - // Put the region to the dirty cards region list. - head = _dirty_cards_region_list; - next = (HeapRegion*) - Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); - if (next == head) { - assert(hr->get_next_dirty_cards_region() == hr, - "hr->get_next_dirty_cards_region() != hr"); - if (next == NULL) { - // The last region in the list points to itself. - hr->set_next_dirty_cards_region(hr); - } else { - hr->set_next_dirty_cards_region(next); - } - } - } while (next != head); - } - } -} - -HeapRegion* G1CollectedHeap::pop_dirty_cards_region() -{ - HeapRegion* head; - HeapRegion* hr; - do { - head = _dirty_cards_region_list; - if (head == NULL) { - return NULL; - } - HeapRegion* new_head = head->get_next_dirty_cards_region(); - if (head == new_head) { - // The last region. - new_head = NULL; - } - hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, - head); - } while (hr != head); - assert(hr != NULL, "invariant"); - hr->set_next_dirty_cards_region(NULL); - return hr; -} - -// Returns true if the reference points to an object that -// can move in an incremental collection. -bool G1CollectedHeap::is_scavengable(const void* p) { - HeapRegion* hr = heap_region_containing(p); - return !hr->is_humongous(); -} - -// Private methods. - -HeapRegion* -G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { - MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); - while (!_secondary_free_list.is_empty() || free_regions_coming()) { - if (!_secondary_free_list.is_empty()) { - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " - "secondary_free_list has %u entries", - _secondary_free_list.length()); - } - // It looks as if there are free regions available on the - // secondary_free_list. Let's move them to the free_list and try - // again to allocate from it. - append_secondary_free_list(); - - assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " - "empty we should have moved at least one entry to the free_list"); - HeapRegion* res = _hrm.allocate_free_region(is_old); - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " - "allocated "HR_FORMAT" from secondary_free_list", - HR_FORMAT_PARAMS(res)); - } - return res; - } - - // Wait here until we get notified either when (a) there are no - // more free regions coming or (b) some regions have been moved on - // the secondary_free_list. - SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); - } - - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " - "could not allocate from secondary_free_list"); - } - return NULL; -} - -HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { - assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, - "the only time we use this to allocate a humongous region is " - "when we are allocating a single humongous region"); - - HeapRegion* res; - if (G1StressConcRegionFreeing) { - if (!_secondary_free_list.is_empty()) { - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " - "forced to look at the secondary_free_list"); - } - res = new_region_try_secondary_free_list(is_old); - if (res != NULL) { - return res; - } - } - } - - res = _hrm.allocate_free_region(is_old); - - if (res == NULL) { - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " - "res == NULL, trying the secondary_free_list"); - } - res = new_region_try_secondary_free_list(is_old); - } - if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { - // Currently, only attempts to allocate GC alloc regions set - // do_expand to true. So, we should only reach here during a - // safepoint. If this assumption changes we might have to - // reconsider the use of _expand_heap_after_alloc_failure. - assert(SafepointSynchronize::is_at_safepoint(), "invariant"); - - ergo_verbose1(ErgoHeapSizing, - "attempt heap expansion", - ergo_format_reason("region allocation request failed") - ergo_format_byte("allocation request"), - word_size * HeapWordSize); - if (expand(word_size * HeapWordSize)) { - // Given that expand() succeeded in expanding the heap, and we - // always expand the heap by an amount aligned to the heap - // region size, the free list should in theory not be empty. - // In either case allocate_free_region() will check for NULL. - res = _hrm.allocate_free_region(is_old); - } else { - _expand_heap_after_alloc_failure = false; - } - } - return res; -} - -HeapWord* -G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, - uint num_regions, - size_t word_size, - AllocationContext_t context) { - assert(first != G1_NO_HRM_INDEX, "pre-condition"); - assert(is_humongous(word_size), "word_size should be humongous"); - assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); - - // Index of last region in the series + 1. - uint last = first + num_regions; - - // We need to initialize the region(s) we just discovered. This is - // a bit tricky given that it can happen concurrently with - // refinement threads refining cards on these regions and - // potentially wanting to refine the BOT as they are scanning - // those cards (this can happen shortly after a cleanup; see CR - // 6991377). So we have to set up the region(s) carefully and in - // a specific order. - - // The word size sum of all the regions we will allocate. - size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; - assert(word_size <= word_size_sum, "sanity"); - - // This will be the "starts humongous" region. - HeapRegion* first_hr = region_at(first); - // The header of the new object will be placed at the bottom of - // the first region. - HeapWord* new_obj = first_hr->bottom(); - // This will be the new end of the first region in the series that - // should also match the end of the last region in the series. - HeapWord* new_end = new_obj + word_size_sum; - // This will be the new top of the first region that will reflect - // this allocation. - HeapWord* new_top = new_obj + word_size; - - // First, we need to zero the header of the space that we will be - // allocating. When we update top further down, some refinement - // threads might try to scan the region. By zeroing the header we - // ensure that any thread that will try to scan the region will - // come across the zero klass word and bail out. - // - // NOTE: It would not have been correct to have used - // CollectedHeap::fill_with_object() and make the space look like - // an int array. The thread that is doing the allocation will - // later update the object header to a potentially different array - // type and, for a very short period of time, the klass and length - // fields will be inconsistent. This could cause a refinement - // thread to calculate the object size incorrectly. - Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); - - // We will set up the first region as "starts humongous". This - // will also update the BOT covering all the regions to reflect - // that there is a single object that starts at the bottom of the - // first region. - first_hr->set_starts_humongous(new_top, new_end); - first_hr->set_allocation_context(context); - // Then, if there are any, we will set up the "continues - // humongous" regions. - HeapRegion* hr = NULL; - for (uint i = first + 1; i < last; ++i) { - hr = region_at(i); - hr->set_continues_humongous(first_hr); - hr->set_allocation_context(context); - } - // If we have "continues humongous" regions (hr != NULL), then the - // end of the last one should match new_end. - assert(hr == NULL || hr->end() == new_end, "sanity"); - - // Up to this point no concurrent thread would have been able to - // do any scanning on any region in this series. All the top - // fields still point to bottom, so the intersection between - // [bottom,top] and [card_start,card_end] will be empty. Before we - // update the top fields, we'll do a storestore to make sure that - // no thread sees the update to top before the zeroing of the - // object header and the BOT initialization. - OrderAccess::storestore(); - - // Now that the BOT and the object header have been initialized, - // we can update top of the "starts humongous" region. - assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), - "new_top should be in this region"); - first_hr->set_top(new_top); - if (_hr_printer.is_active()) { - HeapWord* bottom = first_hr->bottom(); - HeapWord* end = first_hr->orig_end(); - if ((first + 1) == last) { - // the series has a single humongous region - _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); - } else { - // the series has more than one humongous regions - _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); - } - } - - // Now, we will update the top fields of the "continues humongous" - // regions. The reason we need to do this is that, otherwise, - // these regions would look empty and this will confuse parts of - // G1. For example, the code that looks for a consecutive number - // of empty regions will consider them empty and try to - // re-allocate them. We can extend is_empty() to also include - // !is_continues_humongous(), but it is easier to just update the top - // fields here. The way we set top for all regions (i.e., top == - // end for all regions but the last one, top == new_top for the - // last one) is actually used when we will free up the humongous - // region in free_humongous_region(). - hr = NULL; - for (uint i = first + 1; i < last; ++i) { - hr = region_at(i); - if ((i + 1) == last) { - // last continues humongous region - assert(hr->bottom() < new_top && new_top <= hr->end(), - "new_top should fall on this region"); - hr->set_top(new_top); - _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); - } else { - // not last one - assert(new_top > hr->end(), "new_top should be above this region"); - hr->set_top(hr->end()); - _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); - } - } - // If we have continues humongous regions (hr != NULL), then the - // end of the last one should match new_end and its top should - // match new_top. - assert(hr == NULL || - (hr->end() == new_end && hr->top() == new_top), "sanity"); - check_bitmaps("Humongous Region Allocation", first_hr); - - assert(first_hr->used() == word_size * HeapWordSize, "invariant"); - _allocator->increase_used(first_hr->used()); - _humongous_set.add(first_hr); - - return new_obj; -} - -// If could fit into free regions w/o expansion, try. -// Otherwise, if can expand, do so. -// Otherwise, if using ex regions might help, try with ex given back. -HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { - assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); - - verify_region_sets_optional(); - - uint first = G1_NO_HRM_INDEX; - uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); - - if (obj_regions == 1) { - // Only one region to allocate, try to use a fast path by directly allocating - // from the free lists. Do not try to expand here, we will potentially do that - // later. - HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); - if (hr != NULL) { - first = hr->hrm_index(); - } - } else { - // We can't allocate humongous regions spanning more than one region while - // cleanupComplete() is running, since some of the regions we find to be - // empty might not yet be added to the free list. It is not straightforward - // to know in which list they are on so that we can remove them. We only - // need to do this if we need to allocate more than one region to satisfy the - // current humongous allocation request. If we are only allocating one region - // we use the one-region region allocation code (see above), that already - // potentially waits for regions from the secondary free list. - wait_while_free_regions_coming(); - append_secondary_free_list_if_not_empty_with_lock(); - - // Policy: Try only empty regions (i.e. already committed first). Maybe we - // are lucky enough to find some. - first = _hrm.find_contiguous_only_empty(obj_regions); - if (first != G1_NO_HRM_INDEX) { - _hrm.allocate_free_regions_starting_at(first, obj_regions); - } - } - - if (first == G1_NO_HRM_INDEX) { - // Policy: We could not find enough regions for the humongous object in the - // free list. Look through the heap to find a mix of free and uncommitted regions. - // If so, try expansion. - first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); - if (first != G1_NO_HRM_INDEX) { - // We found something. Make sure these regions are committed, i.e. expand - // the heap. Alternatively we could do a defragmentation GC. - ergo_verbose1(ErgoHeapSizing, - "attempt heap expansion", - ergo_format_reason("humongous allocation request failed") - ergo_format_byte("allocation request"), - word_size * HeapWordSize); - - _hrm.expand_at(first, obj_regions); - g1_policy()->record_new_heap_size(num_regions()); - -#ifdef ASSERT - for (uint i = first; i < first + obj_regions; ++i) { - HeapRegion* hr = region_at(i); - assert(hr->is_free(), "sanity"); - assert(hr->is_empty(), "sanity"); - assert(is_on_master_free_list(hr), "sanity"); - } -#endif - _hrm.allocate_free_regions_starting_at(first, obj_regions); - } else { - // Policy: Potentially trigger a defragmentation GC. - } - } - - HeapWord* result = NULL; - if (first != G1_NO_HRM_INDEX) { - result = humongous_obj_allocate_initialize_regions(first, obj_regions, - word_size, context); - assert(result != NULL, "it should always return a valid result"); - - // A successful humongous object allocation changes the used space - // information of the old generation so we need to recalculate the - // sizes and update the jstat counters here. - g1mm()->update_sizes(); - } - - verify_region_sets_optional(); - - return result; -} - -HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { - assert_heap_not_locked_and_not_at_safepoint(); - assert(!is_humongous(word_size), "we do not allow humongous TLABs"); - - uint dummy_gc_count_before; - uint dummy_gclocker_retry_count = 0; - return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); -} - -HeapWord* -G1CollectedHeap::mem_allocate(size_t word_size, - bool* gc_overhead_limit_was_exceeded) { - assert_heap_not_locked_and_not_at_safepoint(); - - // Loop until the allocation is satisfied, or unsatisfied after GC. - for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { - uint gc_count_before; - - HeapWord* result = NULL; - if (!is_humongous(word_size)) { - result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); - } else { - result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); - } - if (result != NULL) { - return result; - } - - // Create the garbage collection operation... - VM_G1CollectForAllocation op(gc_count_before, word_size); - op.set_allocation_context(AllocationContext::current()); - - // ...and get the VM thread to execute it. - VMThread::execute(&op); - - if (op.prologue_succeeded() && op.pause_succeeded()) { - // If the operation was successful we'll return the result even - // if it is NULL. If the allocation attempt failed immediately - // after a Full GC, it's unlikely we'll be able to allocate now. - HeapWord* result = op.result(); - if (result != NULL && !is_humongous(word_size)) { - // Allocations that take place on VM operations do not do any - // card dirtying and we have to do it here. We only have to do - // this for non-humongous allocations, though. - dirty_young_block(result, word_size); - } - return result; - } else { - if (gclocker_retry_count > GCLockerRetryAllocationCount) { - return NULL; - } - assert(op.result() == NULL, - "the result should be NULL if the VM op did not succeed"); - } - - // Give a warning if we seem to be looping forever. - if ((QueuedAllocationWarningCount > 0) && - (try_count % QueuedAllocationWarningCount == 0)) { - warning("G1CollectedHeap::mem_allocate retries %d times", try_count); - } - } - - ShouldNotReachHere(); - return NULL; -} - -HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, - AllocationContext_t context, - uint* gc_count_before_ret, - uint* gclocker_retry_count_ret) { - // Make sure you read the note in attempt_allocation_humongous(). - - assert_heap_not_locked_and_not_at_safepoint(); - assert(!is_humongous(word_size), "attempt_allocation_slow() should not " - "be called for humongous allocation requests"); - - // We should only get here after the first-level allocation attempt - // (attempt_allocation()) failed to allocate. - - // We will loop until a) we manage to successfully perform the - // allocation or b) we successfully schedule a collection which - // fails to perform the allocation. b) is the only case when we'll - // return NULL. - HeapWord* result = NULL; - for (int try_count = 1; /* we'll return */; try_count += 1) { - bool should_try_gc; - uint gc_count_before; - - { - MutexLockerEx x(Heap_lock); - result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, - false /* bot_updates */); - if (result != NULL) { - return result; - } - - // If we reach here, attempt_allocation_locked() above failed to - // allocate a new region. So the mutator alloc region should be NULL. - assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); - - if (GC_locker::is_active_and_needs_gc()) { - if (g1_policy()->can_expand_young_list()) { - // No need for an ergo verbose message here, - // can_expand_young_list() does this when it returns true. - result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, - false /* bot_updates */); - if (result != NULL) { - return result; - } - } - should_try_gc = false; - } else { - // The GCLocker may not be active but the GCLocker initiated - // GC may not yet have been performed (GCLocker::needs_gc() - // returns true). In this case we do not try this GC and - // wait until the GCLocker initiated GC is performed, and - // then retry the allocation. - if (GC_locker::needs_gc()) { - should_try_gc = false; - } else { - // Read the GC count while still holding the Heap_lock. - gc_count_before = total_collections(); - should_try_gc = true; - } - } - } - - if (should_try_gc) { - bool succeeded; - result = do_collection_pause(word_size, gc_count_before, &succeeded, - GCCause::_g1_inc_collection_pause); - if (result != NULL) { - assert(succeeded, "only way to get back a non-NULL result"); - return result; - } - - if (succeeded) { - // If we get here we successfully scheduled a collection which - // failed to allocate. No point in trying to allocate - // further. We'll just return NULL. - MutexLockerEx x(Heap_lock); - *gc_count_before_ret = total_collections(); - return NULL; - } - } else { - if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { - MutexLockerEx x(Heap_lock); - *gc_count_before_ret = total_collections(); - return NULL; - } - // The GCLocker is either active or the GCLocker initiated - // GC has not yet been performed. Stall until it is and - // then retry the allocation. - GC_locker::stall_until_clear(); - (*gclocker_retry_count_ret) += 1; - } - - // We can reach here if we were unsuccessful in scheduling a - // collection (because another thread beat us to it) or if we were - // stalled due to the GC locker. In either can we should retry the - // allocation attempt in case another thread successfully - // performed a collection and reclaimed enough space. We do the - // first attempt (without holding the Heap_lock) here and the - // follow-on attempt will be at the start of the next loop - // iteration (after taking the Heap_lock). - result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, - false /* bot_updates */); - if (result != NULL) { - return result; - } - - // Give a warning if we seem to be looping forever. - if ((QueuedAllocationWarningCount > 0) && - (try_count % QueuedAllocationWarningCount == 0)) { - warning("G1CollectedHeap::attempt_allocation_slow() " - "retries %d times", try_count); - } - } - - ShouldNotReachHere(); - return NULL; -} - -HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, - uint* gc_count_before_ret, - uint* gclocker_retry_count_ret) { - // The structure of this method has a lot of similarities to - // attempt_allocation_slow(). The reason these two were not merged - // into a single one is that such a method would require several "if - // allocation is not humongous do this, otherwise do that" - // conditional paths which would obscure its flow. In fact, an early - // version of this code did use a unified method which was harder to - // follow and, as a result, it had subtle bugs that were hard to - // track down. So keeping these two methods separate allows each to - // be more readable. It will be good to keep these two in sync as - // much as possible. - - assert_heap_not_locked_and_not_at_safepoint(); - assert(is_humongous(word_size), "attempt_allocation_humongous() " - "should only be called for humongous allocations"); - - // Humongous objects can exhaust the heap quickly, so we should check if we - // need to start a marking cycle at each humongous object allocation. We do - // the check before we do the actual allocation. The reason for doing it - // before the allocation is that we avoid having to keep track of the newly - // allocated memory while we do a GC. - if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", - word_size)) { - collect(GCCause::_g1_humongous_allocation); - } - - // We will loop until a) we manage to successfully perform the - // allocation or b) we successfully schedule a collection which - // fails to perform the allocation. b) is the only case when we'll - // return NULL. - HeapWord* result = NULL; - for (int try_count = 1; /* we'll return */; try_count += 1) { - bool should_try_gc; - uint gc_count_before; - - { - MutexLockerEx x(Heap_lock); - - // Given that humongous objects are not allocated in young - // regions, we'll first try to do the allocation without doing a - // collection hoping that there's enough space in the heap. - result = humongous_obj_allocate(word_size, AllocationContext::current()); - if (result != NULL) { - return result; - } - - if (GC_locker::is_active_and_needs_gc()) { - should_try_gc = false; - } else { - // The GCLocker may not be active but the GCLocker initiated - // GC may not yet have been performed (GCLocker::needs_gc() - // returns true). In this case we do not try this GC and - // wait until the GCLocker initiated GC is performed, and - // then retry the allocation. - if (GC_locker::needs_gc()) { - should_try_gc = false; - } else { - // Read the GC count while still holding the Heap_lock. - gc_count_before = total_collections(); - should_try_gc = true; - } - } - } - - if (should_try_gc) { - // If we failed to allocate the humongous object, we should try to - // do a collection pause (if we're allowed) in case it reclaims - // enough space for the allocation to succeed after the pause. - - bool succeeded; - result = do_collection_pause(word_size, gc_count_before, &succeeded, - GCCause::_g1_humongous_allocation); - if (result != NULL) { - assert(succeeded, "only way to get back a non-NULL result"); - return result; - } - - if (succeeded) { - // If we get here we successfully scheduled a collection which - // failed to allocate. No point in trying to allocate - // further. We'll just return NULL. - MutexLockerEx x(Heap_lock); - *gc_count_before_ret = total_collections(); - return NULL; - } - } else { - if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { - MutexLockerEx x(Heap_lock); - *gc_count_before_ret = total_collections(); - return NULL; - } - // The GCLocker is either active or the GCLocker initiated - // GC has not yet been performed. Stall until it is and - // then retry the allocation. - GC_locker::stall_until_clear(); - (*gclocker_retry_count_ret) += 1; - } - - // We can reach here if we were unsuccessful in scheduling a - // collection (because another thread beat us to it) or if we were - // stalled due to the GC locker. In either can we should retry the - // allocation attempt in case another thread successfully - // performed a collection and reclaimed enough space. Give a - // warning if we seem to be looping forever. - - if ((QueuedAllocationWarningCount > 0) && - (try_count % QueuedAllocationWarningCount == 0)) { - warning("G1CollectedHeap::attempt_allocation_humongous() " - "retries %d times", try_count); - } - } - - ShouldNotReachHere(); - return NULL; -} - -HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, - AllocationContext_t context, - bool expect_null_mutator_alloc_region) { - assert_at_safepoint(true /* should_be_vm_thread */); - assert(_allocator->mutator_alloc_region(context)->get() == NULL || - !expect_null_mutator_alloc_region, - "the current alloc region was unexpectedly found to be non-NULL"); - - if (!is_humongous(word_size)) { - return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, - false /* bot_updates */); - } else { - HeapWord* result = humongous_obj_allocate(word_size, context); - if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { - g1_policy()->set_initiate_conc_mark_if_possible(); - } - return result; - } - - ShouldNotReachHere(); -} - -class PostMCRemSetClearClosure: public HeapRegionClosure { - G1CollectedHeap* _g1h; - ModRefBarrierSet* _mr_bs; -public: - PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : - _g1h(g1h), _mr_bs(mr_bs) {} - - bool doHeapRegion(HeapRegion* r) { - HeapRegionRemSet* hrrs = r->rem_set(); - - if (r->is_continues_humongous()) { - // We'll assert that the strong code root list and RSet is empty - assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); - assert(hrrs->occupied() == 0, "RSet should be empty"); - return false; - } - - _g1h->reset_gc_time_stamps(r); - hrrs->clear(); - // You might think here that we could clear just the cards - // corresponding to the used region. But no: if we leave a dirty card - // in a region we might allocate into, then it would prevent that card - // from being enqueued, and cause it to be missed. - // Re: the performance cost: we shouldn't be doing full GC anyway! - _mr_bs->clear(MemRegion(r->bottom(), r->end())); - - return false; - } -}; - -void G1CollectedHeap::clear_rsets_post_compaction() { - PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); - heap_region_iterate(&rs_clear); -} - -class RebuildRSOutOfRegionClosure: public HeapRegionClosure { - G1CollectedHeap* _g1h; - UpdateRSOopClosure _cl; -public: - RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : - _cl(g1->g1_rem_set(), worker_i), - _g1h(g1) - { } - - bool doHeapRegion(HeapRegion* r) { - if (!r->is_continues_humongous()) { - _cl.set_from(r); - r->oop_iterate(&_cl); - } - return false; - } -}; - -class ParRebuildRSTask: public AbstractGangTask { - G1CollectedHeap* _g1; - HeapRegionClaimer _hrclaimer; - -public: - ParRebuildRSTask(G1CollectedHeap* g1) : - AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} - - void work(uint worker_id) { - RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); - _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); - } -}; - -class PostCompactionPrinterClosure: public HeapRegionClosure { -private: - G1HRPrinter* _hr_printer; -public: - bool doHeapRegion(HeapRegion* hr) { - assert(!hr->is_young(), "not expecting to find young regions"); - if (hr->is_free()) { - // We only generate output for non-empty regions. - } else if (hr->is_starts_humongous()) { - if (hr->region_num() == 1) { - // single humongous region - _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); - } else { - _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); - } - } else if (hr->is_continues_humongous()) { - _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); - } else if (hr->is_old()) { - _hr_printer->post_compaction(hr, G1HRPrinter::Old); - } else { - ShouldNotReachHere(); - } - return false; - } - - PostCompactionPrinterClosure(G1HRPrinter* hr_printer) - : _hr_printer(hr_printer) { } -}; - -void G1CollectedHeap::print_hrm_post_compaction() { - PostCompactionPrinterClosure cl(hr_printer()); - heap_region_iterate(&cl); -} - -bool G1CollectedHeap::do_collection(bool explicit_gc, - bool clear_all_soft_refs, - size_t word_size) { - assert_at_safepoint(true /* should_be_vm_thread */); - - if (GC_locker::check_active_before_gc()) { - return false; - } - - STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); - gc_timer->register_gc_start(); - - SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); - gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); - - SvcGCMarker sgcm(SvcGCMarker::FULL); - ResourceMark rm; - - G1Log::update_level(); - print_heap_before_gc(); - trace_heap_before_gc(gc_tracer); - - size_t metadata_prev_used = MetaspaceAux::used_bytes(); - - verify_region_sets_optional(); - - const bool do_clear_all_soft_refs = clear_all_soft_refs || - collector_policy()->should_clear_all_soft_refs(); - - ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); - - { - IsGCActiveMark x; - - // Timing - assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); - TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); - - { - GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); - TraceCollectorStats tcs(g1mm()->full_collection_counters()); - TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); - - g1_policy()->record_full_collection_start(); - - // Note: When we have a more flexible GC logging framework that - // allows us to add optional attributes to a GC log record we - // could consider timing and reporting how long we wait in the - // following two methods. - wait_while_free_regions_coming(); - // If we start the compaction before the CM threads finish - // scanning the root regions we might trip them over as we'll - // be moving objects / updating references. So let's wait until - // they are done. By telling them to abort, they should complete - // early. - _cm->root_regions()->abort(); - _cm->root_regions()->wait_until_scan_finished(); - append_secondary_free_list_if_not_empty_with_lock(); - - gc_prologue(true); - increment_total_collections(true /* full gc */); - increment_old_marking_cycles_started(); - - assert(used() == recalculate_used(), "Should be equal"); - - verify_before_gc(); - - check_bitmaps("Full GC Start"); - pre_full_gc_dump(gc_timer); - - COMPILER2_PRESENT(DerivedPointerTable::clear()); - - // Disable discovery and empty the discovered lists - // for the CM ref processor. - ref_processor_cm()->disable_discovery(); - ref_processor_cm()->abandon_partial_discovery(); - ref_processor_cm()->verify_no_references_recorded(); - - // Abandon current iterations of concurrent marking and concurrent - // refinement, if any are in progress. We have to do this before - // wait_until_scan_finished() below. - concurrent_mark()->abort(); - - // Make sure we'll choose a new allocation region afterwards. - _allocator->release_mutator_alloc_region(); - _allocator->abandon_gc_alloc_regions(); - g1_rem_set()->cleanupHRRS(); - - // We should call this after we retire any currently active alloc - // regions so that all the ALLOC / RETIRE events are generated - // before the start GC event. - _hr_printer.start_gc(true /* full */, (size_t) total_collections()); - - // We may have added regions to the current incremental collection - // set between the last GC or pause and now. We need to clear the - // incremental collection set and then start rebuilding it afresh - // after this full GC. - abandon_collection_set(g1_policy()->inc_cset_head()); - g1_policy()->clear_incremental_cset(); - g1_policy()->stop_incremental_cset_building(); - - tear_down_region_sets(false /* free_list_only */); - g1_policy()->set_gcs_are_young(true); - - // See the comments in g1CollectedHeap.hpp and - // G1CollectedHeap::ref_processing_init() about - // how reference processing currently works in G1. - - // Temporarily make discovery by the STW ref processor single threaded (non-MT). - ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); - - // Temporarily clear the STW ref processor's _is_alive_non_header field. - ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); - - ref_processor_stw()->enable_discovery(); - ref_processor_stw()->setup_policy(do_clear_all_soft_refs); - - // Do collection work - { - HandleMark hm; // Discard invalid handles created during gc - G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); - } - - assert(num_free_regions() == 0, "we should not have added any free regions"); - rebuild_region_sets(false /* free_list_only */); - - // Enqueue any discovered reference objects that have - // not been removed from the discovered lists. - ref_processor_stw()->enqueue_discovered_references(); - - COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); - - MemoryService::track_memory_usage(); - - assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); - ref_processor_stw()->verify_no_references_recorded(); - - // Delete metaspaces for unloaded class loaders and clean up loader_data graph - ClassLoaderDataGraph::purge(); - MetaspaceAux::verify_metrics(); - - // Note: since we've just done a full GC, concurrent - // marking is no longer active. Therefore we need not - // re-enable reference discovery for the CM ref processor. - // That will be done at the start of the next marking cycle. - assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); - ref_processor_cm()->verify_no_references_recorded(); - - reset_gc_time_stamp(); - // Since everything potentially moved, we will clear all remembered - // sets, and clear all cards. Later we will rebuild remembered - // sets. We will also reset the GC time stamps of the regions. - clear_rsets_post_compaction(); - check_gc_time_stamps(); - - // Resize the heap if necessary. - resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); - - if (_hr_printer.is_active()) { - // We should do this after we potentially resize the heap so - // that all the COMMIT / UNCOMMIT events are generated before - // the end GC event. - - print_hrm_post_compaction(); - _hr_printer.end_gc(true /* full */, (size_t) total_collections()); - } - - G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); - if (hot_card_cache->use_cache()) { - hot_card_cache->reset_card_counts(); - hot_card_cache->reset_hot_cache(); - } - - // Rebuild remembered sets of all regions. - uint n_workers = - AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), - workers()->active_workers(), - Threads::number_of_non_daemon_threads()); - assert(UseDynamicNumberOfGCThreads || - n_workers == workers()->total_workers(), - "If not dynamic should be using all the workers"); - workers()->set_active_workers(n_workers); - // Set parallel threads in the heap (_n_par_threads) only - // before a parallel phase and always reset it to 0 after - // the phase so that the number of parallel threads does - // no get carried forward to a serial phase where there - // may be code that is "possibly_parallel". - set_par_threads(n_workers); - - ParRebuildRSTask rebuild_rs_task(this); - assert(UseDynamicNumberOfGCThreads || - workers()->active_workers() == workers()->total_workers(), - "Unless dynamic should use total workers"); - // Use the most recent number of active workers - assert(workers()->active_workers() > 0, - "Active workers not properly set"); - set_par_threads(workers()->active_workers()); - workers()->run_task(&rebuild_rs_task); - set_par_threads(0); - - // Rebuild the strong code root lists for each region - rebuild_strong_code_roots(); - - if (true) { // FIXME - MetaspaceGC::compute_new_size(); - } - -#ifdef TRACESPINNING - ParallelTaskTerminator::print_termination_counts(); -#endif - - // Discard all rset updates - JavaThread::dirty_card_queue_set().abandon_logs(); - assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); - - _young_list->reset_sampled_info(); - // At this point there should be no regions in the - // entire heap tagged as young. - assert(check_young_list_empty(true /* check_heap */), - "young list should be empty at this point"); - - // Update the number of full collections that have been completed. - increment_old_marking_cycles_completed(false /* concurrent */); - - _hrm.verify_optional(); - verify_region_sets_optional(); - - verify_after_gc(); - - // Clear the previous marking bitmap, if needed for bitmap verification. - // Note we cannot do this when we clear the next marking bitmap in - // ConcurrentMark::abort() above since VerifyDuringGC verifies the - // objects marked during a full GC against the previous bitmap. - // But we need to clear it before calling check_bitmaps below since - // the full GC has compacted objects and updated TAMS but not updated - // the prev bitmap. - if (G1VerifyBitmaps) { - ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); - } - check_bitmaps("Full GC End"); - - // Start a new incremental collection set for the next pause - assert(g1_policy()->collection_set() == NULL, "must be"); - g1_policy()->start_incremental_cset_building(); - - clear_cset_fast_test(); - - _allocator->init_mutator_alloc_region(); - - g1_policy()->record_full_collection_end(); - - if (G1Log::fine()) { - g1_policy()->print_heap_transition(); - } - - // We must call G1MonitoringSupport::update_sizes() in the same scoping level - // as an active TraceMemoryManagerStats object (i.e. before the destructor for the - // TraceMemoryManagerStats is called) so that the G1 memory pools are updated - // before any GC notifications are raised. - g1mm()->update_sizes(); - - gc_epilogue(true); - } - - if (G1Log::finer()) { - g1_policy()->print_detailed_heap_transition(true /* full */); - } - - print_heap_after_gc(); - trace_heap_after_gc(gc_tracer); - - post_full_gc_dump(gc_timer); - - gc_timer->register_gc_end(); - gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); - } - - return true; -} - -void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { - // do_collection() will return whether it succeeded in performing - // the GC. Currently, there is no facility on the - // do_full_collection() API to notify the caller than the collection - // did not succeed (e.g., because it was locked out by the GC - // locker). So, right now, we'll ignore the return value. - bool dummy = do_collection(true, /* explicit_gc */ - clear_all_soft_refs, - 0 /* word_size */); -} - -// This code is mostly copied from TenuredGeneration. -void -G1CollectedHeap:: -resize_if_necessary_after_full_collection(size_t word_size) { - // Include the current allocation, if any, and bytes that will be - // pre-allocated to support collections, as "used". - const size_t used_after_gc = used(); - const size_t capacity_after_gc = capacity(); - const size_t free_after_gc = capacity_after_gc - used_after_gc; - - // This is enforced in arguments.cpp. - assert(MinHeapFreeRatio <= MaxHeapFreeRatio, - "otherwise the code below doesn't make sense"); - - // We don't have floating point command-line arguments - const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; - const double maximum_used_percentage = 1.0 - minimum_free_percentage; - const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; - const double minimum_used_percentage = 1.0 - maximum_free_percentage; - - const size_t min_heap_size = collector_policy()->min_heap_byte_size(); - const size_t max_heap_size = collector_policy()->max_heap_byte_size(); - - // We have to be careful here as these two calculations can overflow - // 32-bit size_t's. - double used_after_gc_d = (double) used_after_gc; - double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; - double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; - - // Let's make sure that they are both under the max heap size, which - // by default will make them fit into a size_t. - double desired_capacity_upper_bound = (double) max_heap_size; - minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, - desired_capacity_upper_bound); - maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, - desired_capacity_upper_bound); - - // We can now safely turn them into size_t's. - size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; - size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; - - // This assert only makes sense here, before we adjust them - // with respect to the min and max heap size. - assert(minimum_desired_capacity <= maximum_desired_capacity, - err_msg("minimum_desired_capacity = "SIZE_FORMAT", " - "maximum_desired_capacity = "SIZE_FORMAT, - minimum_desired_capacity, maximum_desired_capacity)); - - // Should not be greater than the heap max size. No need to adjust - // it with respect to the heap min size as it's a lower bound (i.e., - // we'll try to make the capacity larger than it, not smaller). - minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); - // Should not be less than the heap min size. No need to adjust it - // with respect to the heap max size as it's an upper bound (i.e., - // we'll try to make the capacity smaller than it, not greater). - maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); - - if (capacity_after_gc < minimum_desired_capacity) { - // Don't expand unless it's significant - size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; - ergo_verbose4(ErgoHeapSizing, - "attempt heap expansion", - ergo_format_reason("capacity lower than " - "min desired capacity after Full GC") - ergo_format_byte("capacity") - ergo_format_byte("occupancy") - ergo_format_byte_perc("min desired capacity"), - capacity_after_gc, used_after_gc, - minimum_desired_capacity, (double) MinHeapFreeRatio); - expand(expand_bytes); - - // No expansion, now see if we want to shrink - } else if (capacity_after_gc > maximum_desired_capacity) { - // Capacity too large, compute shrinking size - size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; - ergo_verbose4(ErgoHeapSizing, - "attempt heap shrinking", - ergo_format_reason("capacity higher than " - "max desired capacity after Full GC") - ergo_format_byte("capacity") - ergo_format_byte("occupancy") - ergo_format_byte_perc("max desired capacity"), - capacity_after_gc, used_after_gc, - maximum_desired_capacity, (double) MaxHeapFreeRatio); - shrink(shrink_bytes); - } -} - - -HeapWord* -G1CollectedHeap::satisfy_failed_allocation(size_t word_size, - AllocationContext_t context, - bool* succeeded) { - assert_at_safepoint(true /* should_be_vm_thread */); - - *succeeded = true; - // Let's attempt the allocation first. - HeapWord* result = - attempt_allocation_at_safepoint(word_size, - context, - false /* expect_null_mutator_alloc_region */); - if (result != NULL) { - assert(*succeeded, "sanity"); - return result; - } - - // In a G1 heap, we're supposed to keep allocation from failing by - // incremental pauses. Therefore, at least for now, we'll favor - // expansion over collection. (This might change in the future if we can - // do something smarter than full collection to satisfy a failed alloc.) - result = expand_and_allocate(word_size, context); - if (result != NULL) { - assert(*succeeded, "sanity"); - return result; - } - - // Expansion didn't work, we'll try to do a Full GC. - bool gc_succeeded = do_collection(false, /* explicit_gc */ - false, /* clear_all_soft_refs */ - word_size); - if (!gc_succeeded) { - *succeeded = false; - return NULL; - } - - // Retry the allocation - result = attempt_allocation_at_safepoint(word_size, - context, - true /* expect_null_mutator_alloc_region */); - if (result != NULL) { - assert(*succeeded, "sanity"); - return result; - } - - // Then, try a Full GC that will collect all soft references. - gc_succeeded = do_collection(false, /* explicit_gc */ - true, /* clear_all_soft_refs */ - word_size); - if (!gc_succeeded) { - *succeeded = false; - return NULL; - } - - // Retry the allocation once more - result = attempt_allocation_at_safepoint(word_size, - context, - true /* expect_null_mutator_alloc_region */); - if (result != NULL) { - assert(*succeeded, "sanity"); - return result; - } - - assert(!collector_policy()->should_clear_all_soft_refs(), - "Flag should have been handled and cleared prior to this point"); - - // What else? We might try synchronous finalization later. If the total - // space available is large enough for the allocation, then a more - // complete compaction phase than we've tried so far might be - // appropriate. - assert(*succeeded, "sanity"); - return NULL; -} - -// Attempting to expand the heap sufficiently -// to support an allocation of the given "word_size". If -// successful, perform the allocation and return the address of the -// allocated block, or else "NULL". - -HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { - assert_at_safepoint(true /* should_be_vm_thread */); - - verify_region_sets_optional(); - - size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); - ergo_verbose1(ErgoHeapSizing, - "attempt heap expansion", - ergo_format_reason("allocation request failed") - ergo_format_byte("allocation request"), - word_size * HeapWordSize); - if (expand(expand_bytes)) { - _hrm.verify_optional(); - verify_region_sets_optional(); - return attempt_allocation_at_safepoint(word_size, - context, - false /* expect_null_mutator_alloc_region */); - } - return NULL; -} - -bool G1CollectedHeap::expand(size_t expand_bytes) { - size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); - aligned_expand_bytes = align_size_up(aligned_expand_bytes, - HeapRegion::GrainBytes); - ergo_verbose2(ErgoHeapSizing, - "expand the heap", - ergo_format_byte("requested expansion amount") - ergo_format_byte("attempted expansion amount"), - expand_bytes, aligned_expand_bytes); - - if (is_maximal_no_gc()) { - ergo_verbose0(ErgoHeapSizing, - "did not expand the heap", - ergo_format_reason("heap already fully expanded")); - return false; - } - - uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); - assert(regions_to_expand > 0, "Must expand by at least one region"); - - uint expanded_by = _hrm.expand_by(regions_to_expand); - - if (expanded_by > 0) { - size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; - assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); - g1_policy()->record_new_heap_size(num_regions()); - } else { - ergo_verbose0(ErgoHeapSizing, - "did not expand the heap", - ergo_format_reason("heap expansion operation failed")); - // The expansion of the virtual storage space was unsuccessful. - // Let's see if it was because we ran out of swap. - if (G1ExitOnExpansionFailure && - _hrm.available() >= regions_to_expand) { - // We had head room... - vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); - } - } - return regions_to_expand > 0; -} - -void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { - size_t aligned_shrink_bytes = - ReservedSpace::page_align_size_down(shrink_bytes); - aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, - HeapRegion::GrainBytes); - uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); - - uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); - size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; - - ergo_verbose3(ErgoHeapSizing, - "shrink the heap", - ergo_format_byte("requested shrinking amount") - ergo_format_byte("aligned shrinking amount") - ergo_format_byte("attempted shrinking amount"), - shrink_bytes, aligned_shrink_bytes, shrunk_bytes); - if (num_regions_removed > 0) { - g1_policy()->record_new_heap_size(num_regions()); - } else { - ergo_verbose0(ErgoHeapSizing, - "did not shrink the heap", - ergo_format_reason("heap shrinking operation failed")); - } -} - -void G1CollectedHeap::shrink(size_t shrink_bytes) { - verify_region_sets_optional(); - - // We should only reach here at the end of a Full GC which means we - // should not not be holding to any GC alloc regions. The method - // below will make sure of that and do any remaining clean up. - _allocator->abandon_gc_alloc_regions(); - - // Instead of tearing down / rebuilding the free lists here, we - // could instead use the remove_all_pending() method on free_list to - // remove only the ones that we need to remove. - tear_down_region_sets(true /* free_list_only */); - shrink_helper(shrink_bytes); - rebuild_region_sets(true /* free_list_only */); - - _hrm.verify_optional(); - verify_region_sets_optional(); -} - -// Public methods. - -#ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away -#pragma warning( disable:4355 ) // 'this' : used in base member initializer list -#endif // _MSC_VER - - -G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : - CollectedHeap(), - _g1_policy(policy_), - _dirty_card_queue_set(false), - _into_cset_dirty_card_queue_set(false), - _is_alive_closure_cm(this), - _is_alive_closure_stw(this), - _ref_processor_cm(NULL), - _ref_processor_stw(NULL), - _bot_shared(NULL), - _evac_failure_scan_stack(NULL), - _mark_in_progress(false), - _cg1r(NULL), - _g1mm(NULL), - _refine_cte_cl(NULL), - _full_collection(false), - _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), - _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), - _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), - _humongous_reclaim_candidates(), - _has_humongous_reclaim_candidates(false), - _free_regions_coming(false), - _young_list(new YoungList(this)), - _gc_time_stamp(0), - _survivor_plab_stats(YoungPLABSize, PLABWeight), - _old_plab_stats(OldPLABSize, PLABWeight), - _expand_heap_after_alloc_failure(true), - _surviving_young_words(NULL), - _old_marking_cycles_started(0), - _old_marking_cycles_completed(0), - _concurrent_cycle_started(false), - _heap_summary_sent(false), - _in_cset_fast_test(), - _dirty_cards_region_list(NULL), - _worker_cset_start_region(NULL), - _worker_cset_start_region_time_stamp(NULL), - _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), - _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), - _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), - _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { - - _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, - /* are_GC_task_threads */true, - /* are_ConcurrentGC_threads */false); - _workers->initialize_workers(); - - _allocator = G1Allocator::create_allocator(this); - _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; - - int n_queues = MAX2((int)ParallelGCThreads, 1); - _task_queues = new RefToScanQueueSet(n_queues); - - uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); - assert(n_rem_sets > 0, "Invariant."); - - _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); - _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); - _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); - - for (int i = 0; i < n_queues; i++) { - RefToScanQueue* q = new RefToScanQueue(); - q->initialize(); - _task_queues->register_queue(i, q); - ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); - } - clear_cset_start_regions(); - - // Initialize the G1EvacuationFailureALot counters and flags. - NOT_PRODUCT(reset_evacuation_should_fail();) - - guarantee(_task_queues != NULL, "task_queues allocation failure."); -} - -G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, - size_t size, - size_t translation_factor) { - size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); - // Allocate a new reserved space, preferring to use large pages. - ReservedSpace rs(size, preferred_page_size); - G1RegionToSpaceMapper* result = - G1RegionToSpaceMapper::create_mapper(rs, - size, - rs.alignment(), - HeapRegion::GrainBytes, - translation_factor, - mtGC); - if (TracePageSizes) { - gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, - description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); - } - return result; -} - -jint G1CollectedHeap::initialize() { - CollectedHeap::pre_initialize(); - os::enable_vtime(); - - G1Log::init(); - - // Necessary to satisfy locking discipline assertions. - - MutexLocker x(Heap_lock); - - // We have to initialize the printer before committing the heap, as - // it will be used then. - _hr_printer.set_active(G1PrintHeapRegions); - - // While there are no constraints in the GC code that HeapWordSize - // be any particular value, there are multiple other areas in the - // system which believe this to be true (e.g. oop->object_size in some - // cases incorrectly returns the size in wordSize units rather than - // HeapWordSize). - guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); - - size_t init_byte_size = collector_policy()->initial_heap_byte_size(); - size_t max_byte_size = collector_policy()->max_heap_byte_size(); - size_t heap_alignment = collector_policy()->heap_alignment(); - - // Ensure that the sizes are properly aligned. - Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); - Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); - Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); - - _refine_cte_cl = new RefineCardTableEntryClosure(); - - _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); - - // Reserve the maximum. - - // When compressed oops are enabled, the preferred heap base - // is calculated by subtracting the requested size from the - // 32Gb boundary and using the result as the base address for - // heap reservation. If the requested size is not aligned to - // HeapRegion::GrainBytes (i.e. the alignment that is passed - // into the ReservedHeapSpace constructor) then the actual - // base of the reserved heap may end up differing from the - // address that was requested (i.e. the preferred heap base). - // If this happens then we could end up using a non-optimal - // compressed oops mode. - - ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, - heap_alignment); - - initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); - - // Create the barrier set for the entire reserved region. - G1SATBCardTableLoggingModRefBS* bs - = new G1SATBCardTableLoggingModRefBS(reserved_region()); - bs->initialize(); - assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); - set_barrier_set(bs); - - // Also create a G1 rem set. - _g1_rem_set = new G1RemSet(this, g1_barrier_set()); - - // Carve out the G1 part of the heap. - - ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); - size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); - G1RegionToSpaceMapper* heap_storage = - G1RegionToSpaceMapper::create_mapper(g1_rs, - g1_rs.size(), - page_size, - HeapRegion::GrainBytes, - 1, - mtJavaHeap); - os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), - max_byte_size, page_size, - heap_rs.base(), - heap_rs.size()); - heap_storage->set_mapping_changed_listener(&_listener); - - // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. - G1RegionToSpaceMapper* bot_storage = - create_aux_memory_mapper("Block offset table", - G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), - G1BlockOffsetSharedArray::heap_map_factor()); - - ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); - G1RegionToSpaceMapper* cardtable_storage = - create_aux_memory_mapper("Card table", - G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), - G1SATBCardTableLoggingModRefBS::heap_map_factor()); - - G1RegionToSpaceMapper* card_counts_storage = - create_aux_memory_mapper("Card counts table", - G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), - G1CardCounts::heap_map_factor()); - - size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); - G1RegionToSpaceMapper* prev_bitmap_storage = - create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); - G1RegionToSpaceMapper* next_bitmap_storage = - create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); - - _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); - g1_barrier_set()->initialize(cardtable_storage); - // Do later initialization work for concurrent refinement. - _cg1r->init(card_counts_storage); - - // 6843694 - ensure that the maximum region index can fit - // in the remembered set structures. - const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; - guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); - - size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; - guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); - guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, - "too many cards per region"); - - FreeRegionList::set_unrealistically_long_length(max_regions() + 1); - - _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); - - { - HeapWord* start = _hrm.reserved().start(); - HeapWord* end = _hrm.reserved().end(); - size_t granularity = HeapRegion::GrainBytes; - - _in_cset_fast_test.initialize(start, end, granularity); - _humongous_reclaim_candidates.initialize(start, end, granularity); - } - - // Create the ConcurrentMark data structure and thread. - // (Must do this late, so that "max_regions" is defined.) - _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); - if (_cm == NULL || !_cm->completed_initialization()) { - vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); - return JNI_ENOMEM; - } - _cmThread = _cm->cmThread(); - - // Initialize the from_card cache structure of HeapRegionRemSet. - HeapRegionRemSet::init_heap(max_regions()); - - // Now expand into the initial heap size. - if (!expand(init_byte_size)) { - vm_shutdown_during_initialization("Failed to allocate initial heap."); - return JNI_ENOMEM; - } - - // Perform any initialization actions delegated to the policy. - g1_policy()->init(); - - JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, - SATB_Q_FL_lock, - G1SATBProcessCompletedThreshold, - Shared_SATB_Q_lock); - - JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, - DirtyCardQ_CBL_mon, - DirtyCardQ_FL_lock, - concurrent_g1_refine()->yellow_zone(), - concurrent_g1_refine()->red_zone(), - Shared_DirtyCardQ_lock); - - dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code - DirtyCardQ_CBL_mon, - DirtyCardQ_FL_lock, - -1, // never trigger processing - -1, // no limit on length - Shared_DirtyCardQ_lock, - &JavaThread::dirty_card_queue_set()); - - // Initialize the card queue set used to hold cards containing - // references into the collection set. - _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code - DirtyCardQ_CBL_mon, - DirtyCardQ_FL_lock, - -1, // never trigger processing - -1, // no limit on length - Shared_DirtyCardQ_lock, - &JavaThread::dirty_card_queue_set()); - - // Here we allocate the dummy HeapRegion that is required by the - // G1AllocRegion class. - HeapRegion* dummy_region = _hrm.get_dummy_region(); - - // We'll re-use the same region whether the alloc region will - // require BOT updates or not and, if it doesn't, then a non-young - // region will complain that it cannot support allocations without - // BOT updates. So we'll tag the dummy region as eden to avoid that. - dummy_region->set_eden(); - // Make sure it's full. - dummy_region->set_top(dummy_region->end()); - G1AllocRegion::setup(this, dummy_region); - - _allocator->init_mutator_alloc_region(); - - // Do create of the monitoring and management support so that - // values in the heap have been properly initialized. - _g1mm = new G1MonitoringSupport(this); - - G1StringDedup::initialize(); - - return JNI_OK; -} - -void G1CollectedHeap::stop() { - // Stop all concurrent threads. We do this to make sure these threads - // do not continue to execute and access resources (e.g. gclog_or_tty) - // that are destroyed during shutdown. - _cg1r->stop(); - _cmThread->stop(); - if (G1StringDedup::is_enabled()) { - G1StringDedup::stop(); - } -} - -size_t G1CollectedHeap::conservative_max_heap_alignment() { - return HeapRegion::max_region_size(); -} - -void G1CollectedHeap::post_initialize() { - CollectedHeap::post_initialize(); - ref_processing_init(); -} - -void G1CollectedHeap::ref_processing_init() { - // Reference processing in G1 currently works as follows: - // - // * There are two reference processor instances. One is - // used to record and process discovered references - // during concurrent marking; the other is used to - // record and process references during STW pauses - // (both full and incremental). - // * Both ref processors need to 'span' the entire heap as - // the regions in the collection set may be dotted around. - // - // * For the concurrent marking ref processor: - // * Reference discovery is enabled at initial marking. - // * Reference discovery is disabled and the discovered - // references processed etc during remarking. - // * Reference discovery is MT (see below). - // * Reference discovery requires a barrier (see below). - // * Reference processing may or may not be MT - // (depending on the value of ParallelRefProcEnabled - // and ParallelGCThreads). - // * A full GC disables reference discovery by the CM - // ref processor and abandons any entries on it's - // discovered lists. - // - // * For the STW processor: - // * Non MT discovery is enabled at the start of a full GC. - // * Processing and enqueueing during a full GC is non-MT. - // * During a full GC, references are processed after marking. - // - // * Discovery (may or may not be MT) is enabled at the start - // of an incremental evacuation pause. - // * References are processed near the end of a STW evacuation pause. - // * For both types of GC: - // * Discovery is atomic - i.e. not concurrent. - // * Reference discovery will not need a barrier. - - MemRegion mr = reserved_region(); - - // Concurrent Mark ref processor - _ref_processor_cm = - new ReferenceProcessor(mr, // span - ParallelRefProcEnabled && (ParallelGCThreads > 1), - // mt processing - (int) ParallelGCThreads, - // degree of mt processing - (ParallelGCThreads > 1) || (ConcGCThreads > 1), - // mt discovery - (int) MAX2(ParallelGCThreads, ConcGCThreads), - // degree of mt discovery - false, - // Reference discovery is not atomic - &_is_alive_closure_cm); - // is alive closure - // (for efficiency/performance) - - // STW ref processor - _ref_processor_stw = - new ReferenceProcessor(mr, // span - ParallelRefProcEnabled && (ParallelGCThreads > 1), - // mt processing - MAX2((int)ParallelGCThreads, 1), - // degree of mt processing - (ParallelGCThreads > 1), - // mt discovery - MAX2((int)ParallelGCThreads, 1), - // degree of mt discovery - true, - // Reference discovery is atomic - &_is_alive_closure_stw); - // is alive closure - // (for efficiency/performance) -} - -size_t G1CollectedHeap::capacity() const { - return _hrm.length() * HeapRegion::GrainBytes; -} - -void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { - assert(!hr->is_continues_humongous(), "pre-condition"); - hr->reset_gc_time_stamp(); - if (hr->is_starts_humongous()) { - uint first_index = hr->hrm_index() + 1; - uint last_index = hr->last_hc_index(); - for (uint i = first_index; i < last_index; i += 1) { - HeapRegion* chr = region_at(i); - assert(chr->is_continues_humongous(), "sanity"); - chr->reset_gc_time_stamp(); - } - } -} - -#ifndef PRODUCT - -class CheckGCTimeStampsHRClosure : public HeapRegionClosure { -private: - unsigned _gc_time_stamp; - bool _failures; - -public: - CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : - _gc_time_stamp(gc_time_stamp), _failures(false) { } - - virtual bool doHeapRegion(HeapRegion* hr) { - unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); - if (_gc_time_stamp != region_gc_time_stamp) { - gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " - "expected %d", HR_FORMAT_PARAMS(hr), - region_gc_time_stamp, _gc_time_stamp); - _failures = true; - } - return false; - } - - bool failures() { return _failures; } -}; - -void G1CollectedHeap::check_gc_time_stamps() { - CheckGCTimeStampsHRClosure cl(_gc_time_stamp); - heap_region_iterate(&cl); - guarantee(!cl.failures(), "all GC time stamps should have been reset"); -} -#endif // PRODUCT - -void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, - DirtyCardQueue* into_cset_dcq, - bool concurrent, - uint worker_i) { - // Clean cards in the hot card cache - G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); - hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); - - DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); - size_t n_completed_buffers = 0; - while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { - n_completed_buffers++; - } - g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); - dcqs.clear_n_completed_buffers(); - assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); -} - - -// Computes the sum of the storage used by the various regions. -size_t G1CollectedHeap::used() const { - return _allocator->used(); -} - -size_t G1CollectedHeap::used_unlocked() const { - return _allocator->used_unlocked(); -} - -class SumUsedClosure: public HeapRegionClosure { - size_t _used; -public: - SumUsedClosure() : _used(0) {} - bool doHeapRegion(HeapRegion* r) { - if (!r->is_continues_humongous()) { - _used += r->used(); - } - return false; - } - size_t result() { return _used; } -}; - -size_t G1CollectedHeap::recalculate_used() const { - double recalculate_used_start = os::elapsedTime(); - - SumUsedClosure blk; - heap_region_iterate(&blk); - - g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); - return blk.result(); -} - -bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { - switch (cause) { - case GCCause::_gc_locker: return GCLockerInvokesConcurrent; - case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; - case GCCause::_g1_humongous_allocation: return true; - case GCCause::_update_allocation_context_stats_inc: return true; - case GCCause::_wb_conc_mark: return true; - default: return false; - } -} - -#ifndef PRODUCT -void G1CollectedHeap::allocate_dummy_regions() { - // Let's fill up most of the region - size_t word_size = HeapRegion::GrainWords - 1024; - // And as a result the region we'll allocate will be humongous. - guarantee(is_humongous(word_size), "sanity"); - - for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { - // Let's use the existing mechanism for the allocation - HeapWord* dummy_obj = humongous_obj_allocate(word_size, - AllocationContext::system()); - if (dummy_obj != NULL) { - MemRegion mr(dummy_obj, word_size); - CollectedHeap::fill_with_object(mr); - } else { - // If we can't allocate once, we probably cannot allocate - // again. Let's get out of the loop. - break; - } - } -} -#endif // !PRODUCT - -void G1CollectedHeap::increment_old_marking_cycles_started() { - assert(_old_marking_cycles_started == _old_marking_cycles_completed || - _old_marking_cycles_started == _old_marking_cycles_completed + 1, - err_msg("Wrong marking cycle count (started: %d, completed: %d)", - _old_marking_cycles_started, _old_marking_cycles_completed)); - - _old_marking_cycles_started++; -} - -void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { - MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); - - // We assume that if concurrent == true, then the caller is a - // concurrent thread that was joined the Suspendible Thread - // Set. If there's ever a cheap way to check this, we should add an - // assert here. - - // Given that this method is called at the end of a Full GC or of a - // concurrent cycle, and those can be nested (i.e., a Full GC can - // interrupt a concurrent cycle), the number of full collections - // completed should be either one (in the case where there was no - // nesting) or two (when a Full GC interrupted a concurrent cycle) - // behind the number of full collections started. - - // This is the case for the inner caller, i.e. a Full GC. - assert(concurrent || - (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || - (_old_marking_cycles_started == _old_marking_cycles_completed + 2), - err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " - "is inconsistent with _old_marking_cycles_completed = %u", - _old_marking_cycles_started, _old_marking_cycles_completed)); - - // This is the case for the outer caller, i.e. the concurrent cycle. - assert(!concurrent || - (_old_marking_cycles_started == _old_marking_cycles_completed + 1), - err_msg("for outer caller (concurrent cycle): " - "_old_marking_cycles_started = %u " - "is inconsistent with _old_marking_cycles_completed = %u", - _old_marking_cycles_started, _old_marking_cycles_completed)); - - _old_marking_cycles_completed += 1; - - // We need to clear the "in_progress" flag in the CM thread before - // we wake up any waiters (especially when ExplicitInvokesConcurrent - // is set) so that if a waiter requests another System.gc() it doesn't - // incorrectly see that a marking cycle is still in progress. - if (concurrent) { - _cmThread->clear_in_progress(); - } - - // This notify_all() will ensure that a thread that called - // System.gc() with (with ExplicitGCInvokesConcurrent set or not) - // and it's waiting for a full GC to finish will be woken up. It is - // waiting in VM_G1IncCollectionPause::doit_epilogue(). - FullGCCount_lock->notify_all(); -} - -void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { - _concurrent_cycle_started = true; - _gc_timer_cm->register_gc_start(start_time); - - _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); - trace_heap_before_gc(_gc_tracer_cm); -} - -void G1CollectedHeap::register_concurrent_cycle_end() { - if (_concurrent_cycle_started) { - if (_cm->has_aborted()) { - _gc_tracer_cm->report_concurrent_mode_failure(); - } - - _gc_timer_cm->register_gc_end(); - _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); - - // Clear state variables to prepare for the next concurrent cycle. - _concurrent_cycle_started = false; - _heap_summary_sent = false; - } -} - -void G1CollectedHeap::trace_heap_after_concurrent_cycle() { - if (_concurrent_cycle_started) { - // This function can be called when: - // the cleanup pause is run - // the concurrent cycle is aborted before the cleanup pause. - // the concurrent cycle is aborted after the cleanup pause, - // but before the concurrent cycle end has been registered. - // Make sure that we only send the heap information once. - if (!_heap_summary_sent) { - trace_heap_after_gc(_gc_tracer_cm); - _heap_summary_sent = true; - } - } -} - -G1YCType G1CollectedHeap::yc_type() { - bool is_young = g1_policy()->gcs_are_young(); - bool is_initial_mark = g1_policy()->during_initial_mark_pause(); - bool is_during_mark = mark_in_progress(); - - if (is_initial_mark) { - return InitialMark; - } else if (is_during_mark) { - return DuringMark; - } else if (is_young) { - return Normal; - } else { - return Mixed; - } -} - -void G1CollectedHeap::collect(GCCause::Cause cause) { - assert_heap_not_locked(); - - uint gc_count_before; - uint old_marking_count_before; - uint full_gc_count_before; - bool retry_gc; - - do { - retry_gc = false; - - { - MutexLocker ml(Heap_lock); - - // Read the GC count while holding the Heap_lock - gc_count_before = total_collections(); - full_gc_count_before = total_full_collections(); - old_marking_count_before = _old_marking_cycles_started; - } - - if (should_do_concurrent_full_gc(cause)) { - // Schedule an initial-mark evacuation pause that will start a - // concurrent cycle. We're setting word_size to 0 which means that - // we are not requesting a post-GC allocation. - VM_G1IncCollectionPause op(gc_count_before, - 0, /* word_size */ - true, /* should_initiate_conc_mark */ - g1_policy()->max_pause_time_ms(), - cause); - op.set_allocation_context(AllocationContext::current()); - - VMThread::execute(&op); - if (!op.pause_succeeded()) { - if (old_marking_count_before == _old_marking_cycles_started) { - retry_gc = op.should_retry_gc(); - } else { - // A Full GC happened while we were trying to schedule the - // initial-mark GC. No point in starting a new cycle given - // that the whole heap was collected anyway. - } - - if (retry_gc) { - if (GC_locker::is_active_and_needs_gc()) { - GC_locker::stall_until_clear(); - } - } - } - } else { - if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc - DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { - - // Schedule a standard evacuation pause. We're setting word_size - // to 0 which means that we are not requesting a post-GC allocation. - VM_G1IncCollectionPause op(gc_count_before, - 0, /* word_size */ - false, /* should_initiate_conc_mark */ - g1_policy()->max_pause_time_ms(), - cause); - VMThread::execute(&op); - } else { - // Schedule a Full GC. - VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); - VMThread::execute(&op); - } - } - } while (retry_gc); -} - -bool G1CollectedHeap::is_in(const void* p) const { - if (_hrm.reserved().contains(p)) { - // Given that we know that p is in the reserved space, - // heap_region_containing_raw() should successfully - // return the containing region. - HeapRegion* hr = heap_region_containing_raw(p); - return hr->is_in(p); - } else { - return false; - } -} - -#ifdef ASSERT -bool G1CollectedHeap::is_in_exact(const void* p) const { - bool contains = reserved_region().contains(p); - bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); - if (contains && available) { - return true; - } else { - return false; - } -} -#endif - -// Iteration functions. - -// Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. - -class IterateOopClosureRegionClosure: public HeapRegionClosure { - ExtendedOopClosure* _cl; -public: - IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} - bool doHeapRegion(HeapRegion* r) { - if (!r->is_continues_humongous()) { - r->oop_iterate(_cl); - } - return false; - } -}; - -// Iterates an ObjectClosure over all objects within a HeapRegion. - -class IterateObjectClosureRegionClosure: public HeapRegionClosure { - ObjectClosure* _cl; -public: - IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} - bool doHeapRegion(HeapRegion* r) { - if (!r->is_continues_humongous()) { - r->object_iterate(_cl); - } - return false; - } -}; - -void G1CollectedHeap::object_iterate(ObjectClosure* cl) { - IterateObjectClosureRegionClosure blk(cl); - heap_region_iterate(&blk); -} - -void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { - _hrm.iterate(cl); -} - -void -G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, - uint worker_id, - HeapRegionClaimer *hrclaimer, - bool concurrent) const { - _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); -} - -// Clear the cached CSet starting regions and (more importantly) -// the time stamps. Called when we reset the GC time stamp. -void G1CollectedHeap::clear_cset_start_regions() { - assert(_worker_cset_start_region != NULL, "sanity"); - assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); - - int n_queues = MAX2((int)ParallelGCThreads, 1); - for (int i = 0; i < n_queues; i++) { - _worker_cset_start_region[i] = NULL; - _worker_cset_start_region_time_stamp[i] = 0; - } -} - -// Given the id of a worker, obtain or calculate a suitable -// starting region for iterating over the current collection set. -HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { - assert(get_gc_time_stamp() > 0, "should have been updated by now"); - - HeapRegion* result = NULL; - unsigned gc_time_stamp = get_gc_time_stamp(); - - if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { - // Cached starting region for current worker was set - // during the current pause - so it's valid. - // Note: the cached starting heap region may be NULL - // (when the collection set is empty). - result = _worker_cset_start_region[worker_i]; - assert(result == NULL || result->in_collection_set(), "sanity"); - return result; - } - - // The cached entry was not valid so let's calculate - // a suitable starting heap region for this worker. - - // We want the parallel threads to start their collection - // set iteration at different collection set regions to - // avoid contention. - // If we have: - // n collection set regions - // p threads - // Then thread t will start at region floor ((t * n) / p) - - result = g1_policy()->collection_set(); - uint cs_size = g1_policy()->cset_region_length(); - uint active_workers = workers()->active_workers(); - assert(UseDynamicNumberOfGCThreads || - active_workers == workers()->total_workers(), - "Unless dynamic should use total workers"); - - uint end_ind = (cs_size * worker_i) / active_workers; - uint start_ind = 0; - - if (worker_i > 0 && - _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { - // Previous workers starting region is valid - // so let's iterate from there - start_ind = (cs_size * (worker_i - 1)) / active_workers; - result = _worker_cset_start_region[worker_i - 1]; - } - - for (uint i = start_ind; i < end_ind; i++) { - result = result->next_in_collection_set(); - } - - // Note: the calculated starting heap region may be NULL - // (when the collection set is empty). - assert(result == NULL || result->in_collection_set(), "sanity"); - assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, - "should be updated only once per pause"); - _worker_cset_start_region[worker_i] = result; - OrderAccess::storestore(); - _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; - return result; -} - -void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { - HeapRegion* r = g1_policy()->collection_set(); - while (r != NULL) { - HeapRegion* next = r->next_in_collection_set(); - if (cl->doHeapRegion(r)) { - cl->incomplete(); - return; - } - r = next; - } -} - -void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, - HeapRegionClosure *cl) { - if (r == NULL) { - // The CSet is empty so there's nothing to do. - return; - } - - assert(r->in_collection_set(), - "Start region must be a member of the collection set."); - HeapRegion* cur = r; - while (cur != NULL) { - HeapRegion* next = cur->next_in_collection_set(); - if (cl->doHeapRegion(cur) && false) { - cl->incomplete(); - return; - } - cur = next; - } - cur = g1_policy()->collection_set(); - while (cur != r) { - HeapRegion* next = cur->next_in_collection_set(); - if (cl->doHeapRegion(cur) && false) { - cl->incomplete(); - return; - } - cur = next; - } -} - -HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { - HeapRegion* result = _hrm.next_region_in_heap(from); - while (result != NULL && result->is_humongous()) { - result = _hrm.next_region_in_heap(result); - } - return result; -} - -HeapWord* G1CollectedHeap::block_start(const void* addr) const { - HeapRegion* hr = heap_region_containing(addr); - return hr->block_start(addr); -} - -size_t G1CollectedHeap::block_size(const HeapWord* addr) const { - HeapRegion* hr = heap_region_containing(addr); - return hr->block_size(addr); -} - -bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { - HeapRegion* hr = heap_region_containing(addr); - return hr->block_is_obj(addr); -} - -bool G1CollectedHeap::supports_tlab_allocation() const { - return true; -} - -size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { - return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; -} - -size_t G1CollectedHeap::tlab_used(Thread* ignored) const { - return young_list()->eden_used_bytes(); -} - -// For G1 TLABs should not contain humongous objects, so the maximum TLAB size -// must be smaller than the humongous object limit. -size_t G1CollectedHeap::max_tlab_size() const { - return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); -} - -size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { - // Return the remaining space in the cur alloc region, but not less than - // the min TLAB size. - - // Also, this value can be at most the humongous object threshold, - // since we can't allow tlabs to grow big enough to accommodate - // humongous objects. - - HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); - size_t max_tlab = max_tlab_size() * wordSize; - if (hr == NULL) { - return max_tlab; - } else { - return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); - } -} - -size_t G1CollectedHeap::max_capacity() const { - return _hrm.reserved().byte_size(); -} - -jlong G1CollectedHeap::millis_since_last_gc() { - // assert(false, "NYI"); - return 0; -} - -void G1CollectedHeap::prepare_for_verify() { - if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { - ensure_parsability(false); - } - g1_rem_set()->prepare_for_verify(); -} - -bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, - VerifyOption vo) { - switch (vo) { - case VerifyOption_G1UsePrevMarking: - return hr->obj_allocated_since_prev_marking(obj); - case VerifyOption_G1UseNextMarking: - return hr->obj_allocated_since_next_marking(obj); - case VerifyOption_G1UseMarkWord: - return false; - default: - ShouldNotReachHere(); - } - return false; // keep some compilers happy -} - -HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { - switch (vo) { - case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); - case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); - case VerifyOption_G1UseMarkWord: return NULL; - default: ShouldNotReachHere(); - } - return NULL; // keep some compilers happy -} - -bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { - switch (vo) { - case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); - case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); - case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); - default: ShouldNotReachHere(); - } - return false; // keep some compilers happy -} - -const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { - switch (vo) { - case VerifyOption_G1UsePrevMarking: return "PTAMS"; - case VerifyOption_G1UseNextMarking: return "NTAMS"; - case VerifyOption_G1UseMarkWord: return "NONE"; - default: ShouldNotReachHere(); - } - return NULL; // keep some compilers happy -} - -class VerifyRootsClosure: public OopClosure { -private: - G1CollectedHeap* _g1h; - VerifyOption _vo; - bool _failures; -public: - // _vo == UsePrevMarking -> use "prev" marking information, - // _vo == UseNextMarking -> use "next" marking information, - // _vo == UseMarkWord -> use mark word from object header. - VerifyRootsClosure(VerifyOption vo) : - _g1h(G1CollectedHeap::heap()), - _vo(vo), - _failures(false) { } - - bool failures() { return _failures; } - - template void do_oop_nv(T* p) { - T heap_oop = oopDesc::load_heap_oop(p); - if (!oopDesc::is_null(heap_oop)) { - oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); - if (_g1h->is_obj_dead_cond(obj, _vo)) { - gclog_or_tty->print_cr("Root location "PTR_FORMAT" " - "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj)); - if (_vo == VerifyOption_G1UseMarkWord) { - gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark()); - } - obj->print_on(gclog_or_tty); - _failures = true; - } - } - } - - void do_oop(oop* p) { do_oop_nv(p); } - void do_oop(narrowOop* p) { do_oop_nv(p); } -}; - -class G1VerifyCodeRootOopClosure: public OopClosure { - G1CollectedHeap* _g1h; - OopClosure* _root_cl; - nmethod* _nm; - VerifyOption _vo; - bool _failures; - - template void do_oop_work(T* p) { - // First verify that this root is live - _root_cl->do_oop(p); - - if (!G1VerifyHeapRegionCodeRoots) { - // We're not verifying the code roots attached to heap region. - return; - } - - // Don't check the code roots during marking verification in a full GC - if (_vo == VerifyOption_G1UseMarkWord) { - return; - } - - // Now verify that the current nmethod (which contains p) is - // in the code root list of the heap region containing the - // object referenced by p. - - T heap_oop = oopDesc::load_heap_oop(p); - if (!oopDesc::is_null(heap_oop)) { - oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); - - // Now fetch the region containing the object - HeapRegion* hr = _g1h->heap_region_containing(obj); - HeapRegionRemSet* hrrs = hr->rem_set(); - // Verify that the strong code root list for this region - // contains the nmethod - if (!hrrs->strong_code_roots_list_contains(_nm)) { - gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " - "from nmethod "PTR_FORMAT" not in strong " - "code roots for region ["PTR_FORMAT","PTR_FORMAT")", - p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); - _failures = true; - } - } - } - -public: - G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): - _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} - - void do_oop(oop* p) { do_oop_work(p); } - void do_oop(narrowOop* p) { do_oop_work(p); } - - void set_nmethod(nmethod* nm) { _nm = nm; } - bool failures() { return _failures; } -}; - -class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { - G1VerifyCodeRootOopClosure* _oop_cl; - -public: - G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): - _oop_cl(oop_cl) {} - - void do_code_blob(CodeBlob* cb) { - nmethod* nm = cb->as_nmethod_or_null(); - if (nm != NULL) { - _oop_cl->set_nmethod(nm); - nm->oops_do(_oop_cl); - } - } -}; - -class YoungRefCounterClosure : public OopClosure { - G1CollectedHeap* _g1h; - int _count; - public: - YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} - void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } - void do_oop(narrowOop* p) { ShouldNotReachHere(); } - - int count() { return _count; } - void reset_count() { _count = 0; }; -}; - -class VerifyKlassClosure: public KlassClosure { - YoungRefCounterClosure _young_ref_counter_closure; - OopClosure *_oop_closure; - public: - VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} - void do_klass(Klass* k) { - k->oops_do(_oop_closure); - - _young_ref_counter_closure.reset_count(); - k->oops_do(&_young_ref_counter_closure); - if (_young_ref_counter_closure.count() > 0) { - guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k))); - } - } -}; - -class VerifyLivenessOopClosure: public OopClosure { - G1CollectedHeap* _g1h; - VerifyOption _vo; -public: - VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): - _g1h(g1h), _vo(vo) - { } - void do_oop(narrowOop *p) { do_oop_work(p); } - void do_oop( oop *p) { do_oop_work(p); } - - template void do_oop_work(T *p) { - oop obj = oopDesc::load_decode_heap_oop(p); - guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), - "Dead object referenced by a not dead object"); - } -}; - -class VerifyObjsInRegionClosure: public ObjectClosure { -private: - G1CollectedHeap* _g1h; - size_t _live_bytes; - HeapRegion *_hr; - VerifyOption _vo; -public: - // _vo == UsePrevMarking -> use "prev" marking information, - // _vo == UseNextMarking -> use "next" marking information, - // _vo == UseMarkWord -> use mark word from object header. - VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) - : _live_bytes(0), _hr(hr), _vo(vo) { - _g1h = G1CollectedHeap::heap(); - } - void do_object(oop o) { - VerifyLivenessOopClosure isLive(_g1h, _vo); - assert(o != NULL, "Huh?"); - if (!_g1h->is_obj_dead_cond(o, _vo)) { - // If the object is alive according to the mark word, - // then verify that the marking information agrees. - // Note we can't verify the contra-positive of the - // above: if the object is dead (according to the mark - // word), it may not be marked, or may have been marked - // but has since became dead, or may have been allocated - // since the last marking. - if (_vo == VerifyOption_G1UseMarkWord) { - guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); - } - - o->oop_iterate_no_header(&isLive); - if (!_hr->obj_allocated_since_prev_marking(o)) { - size_t obj_size = o->size(); // Make sure we don't overflow - _live_bytes += (obj_size * HeapWordSize); - } - } - } - size_t live_bytes() { return _live_bytes; } -}; - -class VerifyRegionClosure: public HeapRegionClosure { -private: - bool _par; - VerifyOption _vo; - bool _failures; -public: - // _vo == UsePrevMarking -> use "prev" marking information, - // _vo == UseNextMarking -> use "next" marking information, - // _vo == UseMarkWord -> use mark word from object header. - VerifyRegionClosure(bool par, VerifyOption vo) - : _par(par), - _vo(vo), - _failures(false) {} - - bool failures() { - return _failures; - } - - bool doHeapRegion(HeapRegion* r) { - if (!r->is_continues_humongous()) { - bool failures = false; - r->verify(_vo, &failures); - if (failures) { - _failures = true; - } else { - VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); - r->object_iterate(¬_dead_yet_cl); - if (_vo != VerifyOption_G1UseNextMarking) { - if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { - gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " - "max_live_bytes "SIZE_FORMAT" " - "< calculated "SIZE_FORMAT, - p2i(r->bottom()), p2i(r->end()), - r->max_live_bytes(), - not_dead_yet_cl.live_bytes()); - _failures = true; - } - } else { - // When vo == UseNextMarking we cannot currently do a sanity - // check on the live bytes as the calculation has not been - // finalized yet. - } - } - } - return false; // stop the region iteration if we hit a failure - } -}; - -// This is the task used for parallel verification of the heap regions - -class G1ParVerifyTask: public AbstractGangTask { -private: - G1CollectedHeap* _g1h; - VerifyOption _vo; - bool _failures; - HeapRegionClaimer _hrclaimer; - -public: - // _vo == UsePrevMarking -> use "prev" marking information, - // _vo == UseNextMarking -> use "next" marking information, - // _vo == UseMarkWord -> use mark word from object header. - G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : - AbstractGangTask("Parallel verify task"), - _g1h(g1h), - _vo(vo), - _failures(false), - _hrclaimer(g1h->workers()->active_workers()) {} - - bool failures() { - return _failures; - } - - void work(uint worker_id) { - HandleMark hm; - VerifyRegionClosure blk(true, _vo); - _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); - if (blk.failures()) { - _failures = true; - } - } -}; - -void G1CollectedHeap::verify(bool silent, VerifyOption vo) { - if (SafepointSynchronize::is_at_safepoint()) { - assert(Thread::current()->is_VM_thread(), - "Expected to be executed serially by the VM thread at this point"); - - if (!silent) { gclog_or_tty->print("Roots "); } - VerifyRootsClosure rootsCl(vo); - VerifyKlassClosure klassCl(this, &rootsCl); - CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); - - // We apply the relevant closures to all the oops in the - // system dictionary, class loader data graph, the string table - // and the nmethods in the code cache. - G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); - G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); - - { - G1RootProcessor root_processor(this); - root_processor.process_all_roots(&rootsCl, - &cldCl, - &blobsCl); - } - - bool failures = rootsCl.failures() || codeRootsCl.failures(); - - if (vo != VerifyOption_G1UseMarkWord) { - // If we're verifying during a full GC then the region sets - // will have been torn down at the start of the GC. Therefore - // verifying the region sets will fail. So we only verify - // the region sets when not in a full GC. - if (!silent) { gclog_or_tty->print("HeapRegionSets "); } - verify_region_sets(); - } - - if (!silent) { gclog_or_tty->print("HeapRegions "); } - if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { - - G1ParVerifyTask task(this, vo); - assert(UseDynamicNumberOfGCThreads || - workers()->active_workers() == workers()->total_workers(), - "If not dynamic should be using all the workers"); - uint n_workers = workers()->active_workers(); - set_par_threads(n_workers); - workers()->run_task(&task); - set_par_threads(0); - if (task.failures()) { - failures = true; - } - - } else { - VerifyRegionClosure blk(false, vo); - heap_region_iterate(&blk); - if (blk.failures()) { - failures = true; - } - } - - if (G1StringDedup::is_enabled()) { - if (!silent) gclog_or_tty->print("StrDedup "); - G1StringDedup::verify(); - } - - if (failures) { - gclog_or_tty->print_cr("Heap:"); - // It helps to have the per-region information in the output to - // help us track down what went wrong. This is why we call - // print_extended_on() instead of print_on(). - print_extended_on(gclog_or_tty); - gclog_or_tty->cr(); - gclog_or_tty->flush(); - } - guarantee(!failures, "there should not have been any failures"); - } else { - if (!silent) { - gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); - if (G1StringDedup::is_enabled()) { - gclog_or_tty->print(", StrDedup"); - } - gclog_or_tty->print(") "); - } - } -} - -void G1CollectedHeap::verify(bool silent) { - verify(silent, VerifyOption_G1UsePrevMarking); -} - -double G1CollectedHeap::verify(bool guard, const char* msg) { - double verify_time_ms = 0.0; - - if (guard && total_collections() >= VerifyGCStartAt) { - double verify_start = os::elapsedTime(); - HandleMark hm; // Discard invalid handles created during verification - prepare_for_verify(); - Universe::verify(VerifyOption_G1UsePrevMarking, msg); - verify_time_ms = (os::elapsedTime() - verify_start) * 1000; - } - - return verify_time_ms; -} - -void G1CollectedHeap::verify_before_gc() { - double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); - g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); -} - -void G1CollectedHeap::verify_after_gc() { - double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); - g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); -} - -class PrintRegionClosure: public HeapRegionClosure { - outputStream* _st; -public: - PrintRegionClosure(outputStream* st) : _st(st) {} - bool doHeapRegion(HeapRegion* r) { - r->print_on(_st); - return false; - } -}; - -bool G1CollectedHeap::is_obj_dead_cond(const oop obj, - const HeapRegion* hr, - const VerifyOption vo) const { - switch (vo) { - case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); - case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); - case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); - default: ShouldNotReachHere(); - } - return false; // keep some compilers happy -} - -bool G1CollectedHeap::is_obj_dead_cond(const oop obj, - const VerifyOption vo) const { - switch (vo) { - case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); - case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); - case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); - default: ShouldNotReachHere(); - } - return false; // keep some compilers happy -} - -void G1CollectedHeap::print_on(outputStream* st) const { - st->print(" %-20s", "garbage-first heap"); - st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", - capacity()/K, used_unlocked()/K); - st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", - p2i(_hrm.reserved().start()), - p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), - p2i(_hrm.reserved().end())); - st->cr(); - st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); - uint young_regions = _young_list->length(); - st->print("%u young (" SIZE_FORMAT "K), ", young_regions, - (size_t) young_regions * HeapRegion::GrainBytes / K); - uint survivor_regions = g1_policy()->recorded_survivor_regions(); - st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, - (size_t) survivor_regions * HeapRegion::GrainBytes / K); - st->cr(); - MetaspaceAux::print_on(st); -} - -void G1CollectedHeap::print_extended_on(outputStream* st) const { - print_on(st); - - // Print the per-region information. - st->cr(); - st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " - "HS=humongous(starts), HC=humongous(continues), " - "CS=collection set, F=free, TS=gc time stamp, " - "PTAMS=previous top-at-mark-start, " - "NTAMS=next top-at-mark-start)"); - PrintRegionClosure blk(st); - heap_region_iterate(&blk); -} - -void G1CollectedHeap::print_on_error(outputStream* st) const { - this->CollectedHeap::print_on_error(st); - - if (_cm != NULL) { - st->cr(); - _cm->print_on_error(st); - } -} - -void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { - workers()->print_worker_threads_on(st); - _cmThread->print_on(st); - st->cr(); - _cm->print_worker_threads_on(st); - _cg1r->print_worker_threads_on(st); - if (G1StringDedup::is_enabled()) { - G1StringDedup::print_worker_threads_on(st); - } -} - -void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { - workers()->threads_do(tc); - tc->do_thread(_cmThread); - _cg1r->threads_do(tc); - if (G1StringDedup::is_enabled()) { - G1StringDedup::threads_do(tc); - } -} - -void G1CollectedHeap::print_tracing_info() const { - // We'll overload this to mean "trace GC pause statistics." - if (TraceYoungGenTime || TraceOldGenTime) { - // The "G1CollectorPolicy" is keeping track of these stats, so delegate - // to that. - g1_policy()->print_tracing_info(); - } - if (G1SummarizeRSetStats) { - g1_rem_set()->print_summary_info(); - } - if (G1SummarizeConcMark) { - concurrent_mark()->print_summary_info(); - } - g1_policy()->print_yg_surv_rate_info(); -} - -#ifndef PRODUCT -// Helpful for debugging RSet issues. - -class PrintRSetsClosure : public HeapRegionClosure { -private: - const char* _msg; - size_t _occupied_sum; - -public: - bool doHeapRegion(HeapRegion* r) { - HeapRegionRemSet* hrrs = r->rem_set(); - size_t occupied = hrrs->occupied(); - _occupied_sum += occupied; - - gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, - HR_FORMAT_PARAMS(r)); - if (occupied == 0) { - gclog_or_tty->print_cr(" RSet is empty"); - } else { - hrrs->print(); - } - gclog_or_tty->print_cr("----------"); - return false; - } - - PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { - gclog_or_tty->cr(); - gclog_or_tty->print_cr("========================================"); - gclog_or_tty->print_cr("%s", msg); - gclog_or_tty->cr(); - } - - ~PrintRSetsClosure() { - gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); - gclog_or_tty->print_cr("========================================"); - gclog_or_tty->cr(); - } -}; - -void G1CollectedHeap::print_cset_rsets() { - PrintRSetsClosure cl("Printing CSet RSets"); - collection_set_iterate(&cl); -} - -void G1CollectedHeap::print_all_rsets() { - PrintRSetsClosure cl("Printing All RSets");; - heap_region_iterate(&cl); -} -#endif // PRODUCT - -G1CollectedHeap* G1CollectedHeap::heap() { - CollectedHeap* heap = Universe::heap(); - assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); - assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); - return (G1CollectedHeap*)heap; -} - -void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { - // always_do_update_barrier = false; - assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); - // Fill TLAB's and such - accumulate_statistics_all_tlabs(); - ensure_parsability(true); - - if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && - (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { - g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); - } -} - -void G1CollectedHeap::gc_epilogue(bool full) { - - if (G1SummarizeRSetStats && - (G1SummarizeRSetStatsPeriod > 0) && - // we are at the end of the GC. Total collections has already been increased. - ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { - g1_rem_set()->print_periodic_summary_info("After GC RS summary"); - } - - // FIXME: what is this about? - // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" - // is set. - COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), - "derived pointer present")); - // always_do_update_barrier = true; - - resize_all_tlabs(); - allocation_context_stats().update(full); - - // We have just completed a GC. Update the soft reference - // policy with the new heap occupancy - Universe::update_heap_info_at_gc(); -} - -HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, - uint gc_count_before, - bool* succeeded, - GCCause::Cause gc_cause) { - assert_heap_not_locked_and_not_at_safepoint(); - g1_policy()->record_stop_world_start(); - VM_G1IncCollectionPause op(gc_count_before, - word_size, - false, /* should_initiate_conc_mark */ - g1_policy()->max_pause_time_ms(), - gc_cause); - - op.set_allocation_context(AllocationContext::current()); - VMThread::execute(&op); - - HeapWord* result = op.result(); - bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); - assert(result == NULL || ret_succeeded, - "the result should be NULL if the VM did not succeed"); - *succeeded = ret_succeeded; - - assert_heap_not_locked(); - return result; -} - -void -G1CollectedHeap::doConcurrentMark() { - MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); - if (!_cmThread->in_progress()) { - _cmThread->set_started(); - CGC_lock->notify(); - } -} - -size_t G1CollectedHeap::pending_card_num() { - size_t extra_cards = 0; - JavaThread *curr = Threads::first(); - while (curr != NULL) { - DirtyCardQueue& dcq = curr->dirty_card_queue(); - extra_cards += dcq.size(); - curr = curr->next(); - } - DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); - size_t buffer_size = dcqs.buffer_size(); - size_t buffer_num = dcqs.completed_buffers_num(); - - // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes - // in bytes - not the number of 'entries'. We need to convert - // into a number of cards. - return (buffer_size * buffer_num + extra_cards) / oopSize; -} - -size_t G1CollectedHeap::cards_scanned() { - return g1_rem_set()->cardsScanned(); -} - -class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { - private: - size_t _total_humongous; - size_t _candidate_humongous; - - DirtyCardQueue _dcq; - - // We don't nominate objects with many remembered set entries, on - // the assumption that such objects are likely still live. - bool is_remset_small(HeapRegion* region) const { - HeapRegionRemSet* const rset = region->rem_set(); - return G1EagerReclaimHumongousObjectsWithStaleRefs - ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) - : rset->is_empty(); - } - - bool is_typeArray_region(HeapRegion* region) const { - return oop(region->bottom())->is_typeArray(); - } - - bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { - assert(region->is_starts_humongous(), "Must start a humongous object"); - - // Candidate selection must satisfy the following constraints - // while concurrent marking is in progress: - // - // * In order to maintain SATB invariants, an object must not be - // reclaimed if it was allocated before the start of marking and - // has not had its references scanned. Such an object must have - // its references (including type metadata) scanned to ensure no - // live objects are missed by the marking process. Objects - // allocated after the start of concurrent marking don't need to - // be scanned. - // - // * An object must not be reclaimed if it is on the concurrent - // mark stack. Objects allocated after the start of concurrent - // marking are never pushed on the mark stack. - // - // Nominating only objects allocated after the start of concurrent - // marking is sufficient to meet both constraints. This may miss - // some objects that satisfy the constraints, but the marking data - // structures don't support efficiently performing the needed - // additional tests or scrubbing of the mark stack. - // - // However, we presently only nominate is_typeArray() objects. - // A humongous object containing references induces remembered - // set entries on other regions. In order to reclaim such an - // object, those remembered sets would need to be cleaned up. - // - // We also treat is_typeArray() objects specially, allowing them - // to be reclaimed even if allocated before the start of - // concurrent mark. For this we rely on mark stack insertion to - // exclude is_typeArray() objects, preventing reclaiming an object - // that is in the mark stack. We also rely on the metadata for - // such objects to be built-in and so ensured to be kept live. - // Frequent allocation and drop of large binary blobs is an - // important use case for eager reclaim, and this special handling - // may reduce needed headroom. - - return is_typeArray_region(region) && is_remset_small(region); - } - - public: - RegisterHumongousWithInCSetFastTestClosure() - : _total_humongous(0), - _candidate_humongous(0), - _dcq(&JavaThread::dirty_card_queue_set()) { - } - - virtual bool doHeapRegion(HeapRegion* r) { - if (!r->is_starts_humongous()) { - return false; - } - G1CollectedHeap* g1h = G1CollectedHeap::heap(); - - bool is_candidate = humongous_region_is_candidate(g1h, r); - uint rindex = r->hrm_index(); - g1h->set_humongous_reclaim_candidate(rindex, is_candidate); - if (is_candidate) { - _candidate_humongous++; - g1h->register_humongous_region_with_cset(rindex); - // Is_candidate already filters out humongous object with large remembered sets. - // If we have a humongous object with a few remembered sets, we simply flush these - // remembered set entries into the DCQS. That will result in automatic - // re-evaluation of their remembered set entries during the following evacuation - // phase. - if (!r->rem_set()->is_empty()) { - guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), - "Found a not-small remembered set here. This is inconsistent with previous assumptions."); - G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); - HeapRegionRemSetIterator hrrs(r->rem_set()); - size_t card_index; - while (hrrs.has_next(card_index)) { - jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); - // The remembered set might contain references to already freed - // regions. Filter out such entries to avoid failing card table - // verification. - if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { - if (*card_ptr != CardTableModRefBS::dirty_card_val()) { - *card_ptr = CardTableModRefBS::dirty_card_val(); - _dcq.enqueue(card_ptr); - } - } - } - r->rem_set()->clear_locked(); - } - assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); - } - _total_humongous++; - - return false; - } - - size_t total_humongous() const { return _total_humongous; } - size_t candidate_humongous() const { return _candidate_humongous; } - - void flush_rem_set_entries() { _dcq.flush(); } -}; - -void G1CollectedHeap::register_humongous_regions_with_cset() { - if (!G1EagerReclaimHumongousObjects) { - g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); - return; - } - double time = os::elapsed_counter(); - - // Collect reclaim candidate information and register candidates with cset. - RegisterHumongousWithInCSetFastTestClosure cl; - heap_region_iterate(&cl); - - time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; - g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, - cl.total_humongous(), - cl.candidate_humongous()); - _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; - - // Finally flush all remembered set entries to re-check into the global DCQS. - cl.flush_rem_set_entries(); -} - -void -G1CollectedHeap::setup_surviving_young_words() { - assert(_surviving_young_words == NULL, "pre-condition"); - uint array_length = g1_policy()->young_cset_region_length(); - _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); - if (_surviving_young_words == NULL) { - vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, - "Not enough space for young surv words summary."); - } - memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); -#ifdef ASSERT - for (uint i = 0; i < array_length; ++i) { - assert( _surviving_young_words[i] == 0, "memset above" ); - } -#endif // !ASSERT -} - -void -G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { - MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); - uint array_length = g1_policy()->young_cset_region_length(); - for (uint i = 0; i < array_length; ++i) { - _surviving_young_words[i] += surv_young_words[i]; - } -} - -void -G1CollectedHeap::cleanup_surviving_young_words() { - guarantee( _surviving_young_words != NULL, "pre-condition" ); - FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); - _surviving_young_words = NULL; -} - -#ifdef ASSERT -class VerifyCSetClosure: public HeapRegionClosure { -public: - bool doHeapRegion(HeapRegion* hr) { - // Here we check that the CSet region's RSet is ready for parallel - // iteration. The fields that we'll verify are only manipulated - // when the region is part of a CSet and is collected. Afterwards, - // we reset these fields when we clear the region's RSet (when the - // region is freed) so they are ready when the region is - // re-allocated. The only exception to this is if there's an - // evacuation failure and instead of freeing the region we leave - // it in the heap. In that case, we reset these fields during - // evacuation failure handling. - guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); - - // Here's a good place to add any other checks we'd like to - // perform on CSet regions. - return false; - } -}; -#endif // ASSERT - -#if TASKQUEUE_STATS -void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { - st->print_raw_cr("GC Task Stats"); - st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); - st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); -} - -void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { - print_taskqueue_stats_hdr(st); - - TaskQueueStats totals; - const uint n = workers()->total_workers(); - for (uint i = 0; i < n; ++i) { - st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); - totals += task_queue(i)->stats; - } - st->print_raw("tot "); totals.print(st); st->cr(); - - DEBUG_ONLY(totals.verify()); -} - -void G1CollectedHeap::reset_taskqueue_stats() { - const uint n = workers()->total_workers(); - for (uint i = 0; i < n; ++i) { - task_queue(i)->stats.reset(); - } -} -#endif // TASKQUEUE_STATS - -void G1CollectedHeap::log_gc_header() { - if (!G1Log::fine()) { - return; - } - - gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); - - GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) - .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") - .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); - - gclog_or_tty->print("[%s", (const char*)gc_cause_str); -} - -void G1CollectedHeap::log_gc_footer(double pause_time_sec) { - if (!G1Log::fine()) { - return; - } - - if (G1Log::finer()) { - if (evacuation_failed()) { - gclog_or_tty->print(" (to-space exhausted)"); - } - gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); - g1_policy()->phase_times()->note_gc_end(); - g1_policy()->phase_times()->print(pause_time_sec); - g1_policy()->print_detailed_heap_transition(); - } else { - if (evacuation_failed()) { - gclog_or_tty->print("--"); - } - g1_policy()->print_heap_transition(); - gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); - } - gclog_or_tty->flush(); -} - -bool -G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { - assert_at_safepoint(true /* should_be_vm_thread */); - guarantee(!is_gc_active(), "collection is not reentrant"); - - if (GC_locker::check_active_before_gc()) { - return false; - } - - _gc_timer_stw->register_gc_start(); - - _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); - - SvcGCMarker sgcm(SvcGCMarker::MINOR); - ResourceMark rm; - - G1Log::update_level(); - print_heap_before_gc(); - trace_heap_before_gc(_gc_tracer_stw); - - verify_region_sets_optional(); - verify_dirty_young_regions(); - - // This call will decide whether this pause is an initial-mark - // pause. If it is, during_initial_mark_pause() will return true - // for the duration of this pause. - g1_policy()->decide_on_conc_mark_initiation(); - - // We do not allow initial-mark to be piggy-backed on a mixed GC. - assert(!g1_policy()->during_initial_mark_pause() || - g1_policy()->gcs_are_young(), "sanity"); - - // We also do not allow mixed GCs during marking. - assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); - - // Record whether this pause is an initial mark. When the current - // thread has completed its logging output and it's safe to signal - // the CM thread, the flag's value in the policy has been reset. - bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); - - // Inner scope for scope based logging, timers, and stats collection - { - EvacuationInfo evacuation_info; - - if (g1_policy()->during_initial_mark_pause()) { - // We are about to start a marking cycle, so we increment the - // full collection counter. - increment_old_marking_cycles_started(); - register_concurrent_cycle_start(_gc_timer_stw->gc_start()); - } - - _gc_tracer_stw->report_yc_type(yc_type()); - - TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); - - uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), - workers()->active_workers(), - Threads::number_of_non_daemon_threads()); - assert(UseDynamicNumberOfGCThreads || - active_workers == workers()->total_workers(), - "If not dynamic should be using all the workers"); - workers()->set_active_workers(active_workers); - - double pause_start_sec = os::elapsedTime(); - g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); - log_gc_header(); - - TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); - TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); - - // If the secondary_free_list is not empty, append it to the - // free_list. No need to wait for the cleanup operation to finish; - // the region allocation code will check the secondary_free_list - // and wait if necessary. If the G1StressConcRegionFreeing flag is - // set, skip this step so that the region allocation code has to - // get entries from the secondary_free_list. - if (!G1StressConcRegionFreeing) { - append_secondary_free_list_if_not_empty_with_lock(); - } - - assert(check_young_list_well_formed(), "young list should be well formed"); - - // Don't dynamically change the number of GC threads this early. A value of - // 0 is used to indicate serial work. When parallel work is done, - // it will be set. - - { // Call to jvmpi::post_class_unload_events must occur outside of active GC - IsGCActiveMark x; - - gc_prologue(false); - increment_total_collections(false /* full gc */); - increment_gc_time_stamp(); - - verify_before_gc(); - - check_bitmaps("GC Start"); - - COMPILER2_PRESENT(DerivedPointerTable::clear()); - - // Please see comment in g1CollectedHeap.hpp and - // G1CollectedHeap::ref_processing_init() to see how - // reference processing currently works in G1. - - // Enable discovery in the STW reference processor - ref_processor_stw()->enable_discovery(); - - { - // We want to temporarily turn off discovery by the - // CM ref processor, if necessary, and turn it back on - // on again later if we do. Using a scoped - // NoRefDiscovery object will do this. - NoRefDiscovery no_cm_discovery(ref_processor_cm()); - - // Forget the current alloc region (we might even choose it to be part - // of the collection set!). - _allocator->release_mutator_alloc_region(); - - // We should call this after we retire the mutator alloc - // region(s) so that all the ALLOC / RETIRE events are generated - // before the start GC event. - _hr_printer.start_gc(false /* full */, (size_t) total_collections()); - - // This timing is only used by the ergonomics to handle our pause target. - // It is unclear why this should not include the full pause. We will - // investigate this in CR 7178365. - // - // Preserving the old comment here if that helps the investigation: - // - // The elapsed time induced by the start time below deliberately elides - // the possible verification above. - double sample_start_time_sec = os::elapsedTime(); - -#if YOUNG_LIST_VERBOSE - gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); - _young_list->print(); - g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); -#endif // YOUNG_LIST_VERBOSE - - g1_policy()->record_collection_pause_start(sample_start_time_sec); - - double scan_wait_start = os::elapsedTime(); - // We have to wait until the CM threads finish scanning the - // root regions as it's the only way to ensure that all the - // objects on them have been correctly scanned before we start - // moving them during the GC. - bool waited = _cm->root_regions()->wait_until_scan_finished(); - double wait_time_ms = 0.0; - if (waited) { - double scan_wait_end = os::elapsedTime(); - wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; - } - g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); - -#if YOUNG_LIST_VERBOSE - gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); - _young_list->print(); -#endif // YOUNG_LIST_VERBOSE - - if (g1_policy()->during_initial_mark_pause()) { - concurrent_mark()->checkpointRootsInitialPre(); - } - -#if YOUNG_LIST_VERBOSE - gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); - _young_list->print(); - g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); -#endif // YOUNG_LIST_VERBOSE - - g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); - - register_humongous_regions_with_cset(); - - assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); - - _cm->note_start_of_gc(); - // We call this after finalize_cset() to - // ensure that the CSet has been finalized. - _cm->verify_no_cset_oops(); - - if (_hr_printer.is_active()) { - HeapRegion* hr = g1_policy()->collection_set(); - while (hr != NULL) { - _hr_printer.cset(hr); - hr = hr->next_in_collection_set(); - } - } - -#ifdef ASSERT - VerifyCSetClosure cl; - collection_set_iterate(&cl); -#endif // ASSERT - - setup_surviving_young_words(); - - // Initialize the GC alloc regions. - _allocator->init_gc_alloc_regions(evacuation_info); - - // Actually do the work... - evacuate_collection_set(evacuation_info); - - free_collection_set(g1_policy()->collection_set(), evacuation_info); - - eagerly_reclaim_humongous_regions(); - - g1_policy()->clear_collection_set(); - - cleanup_surviving_young_words(); - - // Start a new incremental collection set for the next pause. - g1_policy()->start_incremental_cset_building(); - - clear_cset_fast_test(); - - _young_list->reset_sampled_info(); - - // Don't check the whole heap at this point as the - // GC alloc regions from this pause have been tagged - // as survivors and moved on to the survivor list. - // Survivor regions will fail the !is_young() check. - assert(check_young_list_empty(false /* check_heap */), - "young list should be empty"); - -#if YOUNG_LIST_VERBOSE - gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); - _young_list->print(); -#endif // YOUNG_LIST_VERBOSE - - g1_policy()->record_survivor_regions(_young_list->survivor_length(), - _young_list->first_survivor_region(), - _young_list->last_survivor_region()); - - _young_list->reset_auxilary_lists(); - - if (evacuation_failed()) { - _allocator->set_used(recalculate_used()); - uint n_queues = MAX2((int)ParallelGCThreads, 1); - for (uint i = 0; i < n_queues; i++) { - if (_evacuation_failed_info_array[i].has_failed()) { - _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); - } - } - } else { - // The "used" of the the collection set have already been subtracted - // when they were freed. Add in the bytes evacuated. - _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); - } - - if (g1_policy()->during_initial_mark_pause()) { - // We have to do this before we notify the CM threads that - // they can start working to make sure that all the - // appropriate initialization is done on the CM object. - concurrent_mark()->checkpointRootsInitialPost(); - set_marking_started(); - // Note that we don't actually trigger the CM thread at - // this point. We do that later when we're sure that - // the current thread has completed its logging output. - } - - allocate_dummy_regions(); - -#if YOUNG_LIST_VERBOSE - gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); - _young_list->print(); - g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); -#endif // YOUNG_LIST_VERBOSE - - _allocator->init_mutator_alloc_region(); - - { - size_t expand_bytes = g1_policy()->expansion_amount(); - if (expand_bytes > 0) { - size_t bytes_before = capacity(); - // No need for an ergo verbose message here, - // expansion_amount() does this when it returns a value > 0. - if (!expand(expand_bytes)) { - // We failed to expand the heap. Cannot do anything about it. - } - } - } - - // We redo the verification but now wrt to the new CSet which - // has just got initialized after the previous CSet was freed. - _cm->verify_no_cset_oops(); - _cm->note_end_of_gc(); - - // This timing is only used by the ergonomics to handle our pause target. - // It is unclear why this should not include the full pause. We will - // investigate this in CR 7178365. - double sample_end_time_sec = os::elapsedTime(); - double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; - g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); - - MemoryService::track_memory_usage(); - - // In prepare_for_verify() below we'll need to scan the deferred - // update buffers to bring the RSets up-to-date if - // G1HRRSFlushLogBuffersOnVerify has been set. While scanning - // the update buffers we'll probably need to scan cards on the - // regions we just allocated to (i.e., the GC alloc - // regions). However, during the last GC we called - // set_saved_mark() on all the GC alloc regions, so card - // scanning might skip the [saved_mark_word()...top()] area of - // those regions (i.e., the area we allocated objects into - // during the last GC). But it shouldn't. Given that - // saved_mark_word() is conditional on whether the GC time stamp - // on the region is current or not, by incrementing the GC time - // stamp here we invalidate all the GC time stamps on all the - // regions and saved_mark_word() will simply return top() for - // all the regions. This is a nicer way of ensuring this rather - // than iterating over the regions and fixing them. In fact, the - // GC time stamp increment here also ensures that - // saved_mark_word() will return top() between pauses, i.e., - // during concurrent refinement. So we don't need the - // is_gc_active() check to decided which top to use when - // scanning cards (see CR 7039627). - increment_gc_time_stamp(); - - verify_after_gc(); - check_bitmaps("GC End"); - - assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); - ref_processor_stw()->verify_no_references_recorded(); - - // CM reference discovery will be re-enabled if necessary. - } - - // We should do this after we potentially expand the heap so - // that all the COMMIT events are generated before the end GC - // event, and after we retire the GC alloc regions so that all - // RETIRE events are generated before the end GC event. - _hr_printer.end_gc(false /* full */, (size_t) total_collections()); - -#ifdef TRACESPINNING - ParallelTaskTerminator::print_termination_counts(); -#endif - - gc_epilogue(false); - } - - // Print the remainder of the GC log output. - log_gc_footer(os::elapsedTime() - pause_start_sec); - - // It is not yet to safe to tell the concurrent mark to - // start as we have some optional output below. We don't want the - // output from the concurrent mark thread interfering with this - // logging output either. - - _hrm.verify_optional(); - verify_region_sets_optional(); - - TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); - TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); - - print_heap_after_gc(); - trace_heap_after_gc(_gc_tracer_stw); - - // We must call G1MonitoringSupport::update_sizes() in the same scoping level - // as an active TraceMemoryManagerStats object (i.e. before the destructor for the - // TraceMemoryManagerStats is called) so that the G1 memory pools are updated - // before any GC notifications are raised. - g1mm()->update_sizes(); - - _gc_tracer_stw->report_evacuation_info(&evacuation_info); - _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); - _gc_timer_stw->register_gc_end(); - _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); - } - // It should now be safe to tell the concurrent mark thread to start - // without its logging output interfering with the logging output - // that came from the pause. - - if (should_start_conc_mark) { - // CAUTION: after the doConcurrentMark() call below, - // the concurrent marking thread(s) could be running - // concurrently with us. Make sure that anything after - // this point does not assume that we are the only GC thread - // running. Note: of course, the actual marking work will - // not start until the safepoint itself is released in - // SuspendibleThreadSet::desynchronize(). - doConcurrentMark(); - } - - return true; -} - -void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { - _drain_in_progress = false; - set_evac_failure_closure(cl); - _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray(40, true); -} - -void G1CollectedHeap::finalize_for_evac_failure() { - assert(_evac_failure_scan_stack != NULL && - _evac_failure_scan_stack->length() == 0, - "Postcondition"); - assert(!_drain_in_progress, "Postcondition"); - delete _evac_failure_scan_stack; - _evac_failure_scan_stack = NULL; -} - -void G1CollectedHeap::remove_self_forwarding_pointers() { - double remove_self_forwards_start = os::elapsedTime(); - - set_par_threads(); - G1ParRemoveSelfForwardPtrsTask rsfp_task(this); - workers()->run_task(&rsfp_task); - set_par_threads(0); - - // Now restore saved marks, if any. - assert(_objs_with_preserved_marks.size() == - _preserved_marks_of_objs.size(), "Both or none."); - while (!_objs_with_preserved_marks.is_empty()) { - oop obj = _objs_with_preserved_marks.pop(); - markOop m = _preserved_marks_of_objs.pop(); - obj->set_mark(m); - } - _objs_with_preserved_marks.clear(true); - _preserved_marks_of_objs.clear(true); - - g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); -} - -void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { - _evac_failure_scan_stack->push(obj); -} - -void G1CollectedHeap::drain_evac_failure_scan_stack() { - assert(_evac_failure_scan_stack != NULL, "precondition"); - - while (_evac_failure_scan_stack->length() > 0) { - oop obj = _evac_failure_scan_stack->pop(); - _evac_failure_closure->set_region(heap_region_containing(obj)); - obj->oop_iterate_backwards(_evac_failure_closure); - } -} - -oop -G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, - oop old) { - assert(obj_in_cs(old), - err_msg("obj: "PTR_FORMAT" should still be in the CSet", - p2i(old))); - markOop m = old->mark(); - oop forward_ptr = old->forward_to_atomic(old); - if (forward_ptr == NULL) { - // Forward-to-self succeeded. - assert(_par_scan_state != NULL, "par scan state"); - OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); - uint queue_num = _par_scan_state->queue_num(); - - _evacuation_failed = true; - _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); - if (_evac_failure_closure != cl) { - MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); - assert(!_drain_in_progress, - "Should only be true while someone holds the lock."); - // Set the global evac-failure closure to the current thread's. - assert(_evac_failure_closure == NULL, "Or locking has failed."); - set_evac_failure_closure(cl); - // Now do the common part. - handle_evacuation_failure_common(old, m); - // Reset to NULL. - set_evac_failure_closure(NULL); - } else { - // The lock is already held, and this is recursive. - assert(_drain_in_progress, "This should only be the recursive case."); - handle_evacuation_failure_common(old, m); - } - return old; - } else { - // Forward-to-self failed. Either someone else managed to allocate - // space for this object (old != forward_ptr) or they beat us in - // self-forwarding it (old == forward_ptr). - assert(old == forward_ptr || !obj_in_cs(forward_ptr), - err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " - "should not be in the CSet", - p2i(old), p2i(forward_ptr))); - return forward_ptr; - } -} - -void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { - preserve_mark_if_necessary(old, m); - - HeapRegion* r = heap_region_containing(old); - if (!r->evacuation_failed()) { - r->set_evacuation_failed(true); - _hr_printer.evac_failure(r); - } - - push_on_evac_failure_scan_stack(old); - - if (!_drain_in_progress) { - // prevent recursion in copy_to_survivor_space() - _drain_in_progress = true; - drain_evac_failure_scan_stack(); - _drain_in_progress = false; - } -} - -void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { - assert(evacuation_failed(), "Oversaving!"); - // We want to call the "for_promotion_failure" version only in the - // case of a promotion failure. - if (m->must_be_preserved_for_promotion_failure(obj)) { - _objs_with_preserved_marks.push(obj); - _preserved_marks_of_objs.push(m); - } -} - -void G1ParCopyHelper::mark_object(oop obj) { - assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); - - // We know that the object is not moving so it's safe to read its size. - _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); -} - -void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { - assert(from_obj->is_forwarded(), "from obj should be forwarded"); - assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); - assert(from_obj != to_obj, "should not be self-forwarded"); - - assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); - assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); - - // The object might be in the process of being copied by another - // worker so we cannot trust that its to-space image is - // well-formed. So we have to read its size from its from-space - // image which we know should not be changing. - _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); -} - -template -void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { - if (_g1->heap_region_containing_raw(new_obj)->is_young()) { - _scanned_klass->record_modified_oops(); - } -} - -template -template -void G1ParCopyClosure::do_oop_work(T* p) { - T heap_oop = oopDesc::load_heap_oop(p); - - if (oopDesc::is_null(heap_oop)) { - return; - } - - oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); - - assert(_worker_id == _par_scan_state->queue_num(), "sanity"); - - const InCSetState state = _g1->in_cset_state(obj); - if (state.is_in_cset()) { - oop forwardee; - markOop m = obj->mark(); - if (m->is_marked()) { - forwardee = (oop) m->decode_pointer(); - } else { - forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); - } - assert(forwardee != NULL, "forwardee should not be NULL"); - oopDesc::encode_store_heap_oop(p, forwardee); - if (do_mark_object != G1MarkNone && forwardee != obj) { - // If the object is self-forwarded we don't need to explicitly - // mark it, the evacuation failure protocol will do so. - mark_forwarded_object(obj, forwardee); - } - - if (barrier == G1BarrierKlass) { - do_klass_barrier(p, forwardee); - } - } else { - if (state.is_humongous()) { - _g1->set_humongous_is_live(obj); - } - // The object is not in collection set. If we're a root scanning - // closure during an initial mark pause then attempt to mark the object. - if (do_mark_object == G1MarkFromRoot) { - mark_object(obj); - } - } - - if (barrier == G1BarrierEvac) { - _par_scan_state->update_rs(_from, p, _worker_id); - } -} - -template void G1ParCopyClosure::do_oop_work(oop* p); -template void G1ParCopyClosure::do_oop_work(narrowOop* p); - -class G1ParEvacuateFollowersClosure : public VoidClosure { -protected: - G1CollectedHeap* _g1h; - G1ParScanThreadState* _par_scan_state; - RefToScanQueueSet* _queues; - ParallelTaskTerminator* _terminator; - - G1ParScanThreadState* par_scan_state() { return _par_scan_state; } - RefToScanQueueSet* queues() { return _queues; } - ParallelTaskTerminator* terminator() { return _terminator; } - -public: - G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, - G1ParScanThreadState* par_scan_state, - RefToScanQueueSet* queues, - ParallelTaskTerminator* terminator) - : _g1h(g1h), _par_scan_state(par_scan_state), - _queues(queues), _terminator(terminator) {} - - void do_void(); - -private: - inline bool offer_termination(); -}; - -bool G1ParEvacuateFollowersClosure::offer_termination() { - G1ParScanThreadState* const pss = par_scan_state(); - pss->start_term_time(); - const bool res = terminator()->offer_termination(); - pss->end_term_time(); - return res; -} - -void G1ParEvacuateFollowersClosure::do_void() { - G1ParScanThreadState* const pss = par_scan_state(); - pss->trim_queue(); - do { - pss->steal_and_trim_queue(queues()); - } while (!offer_termination()); -} - -class G1KlassScanClosure : public KlassClosure { - G1ParCopyHelper* _closure; - bool _process_only_dirty; - int _count; - public: - G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) - : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} - void do_klass(Klass* klass) { - // If the klass has not been dirtied we know that there's - // no references into the young gen and we can skip it. - if (!_process_only_dirty || klass->has_modified_oops()) { - // Clean the klass since we're going to scavenge all the metadata. - klass->clear_modified_oops(); - - // Tell the closure that this klass is the Klass to scavenge - // and is the one to dirty if oops are left pointing into the young gen. - _closure->set_scanned_klass(klass); - - klass->oops_do(_closure); - - _closure->set_scanned_klass(NULL); - } - _count++; - } -}; - -class G1ParTask : public AbstractGangTask { -protected: - G1CollectedHeap* _g1h; - RefToScanQueueSet *_queues; - G1RootProcessor* _root_processor; - ParallelTaskTerminator _terminator; - uint _n_workers; - - Mutex _stats_lock; - Mutex* stats_lock() { return &_stats_lock; } - -public: - G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) - : AbstractGangTask("G1 collection"), - _g1h(g1h), - _queues(task_queues), - _root_processor(root_processor), - _terminator(0, _queues), - _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) - {} - - RefToScanQueueSet* queues() { return _queues; } - - RefToScanQueue *work_queue(int i) { - return queues()->queue(i); - } - - ParallelTaskTerminator* terminator() { return &_terminator; } - - virtual void set_for_termination(uint active_workers) { - _root_processor->set_num_workers(active_workers); - terminator()->reset_for_reuse(active_workers); - _n_workers = active_workers; - } - - // Helps out with CLD processing. - // - // During InitialMark we need to: - // 1) Scavenge all CLDs for the young GC. - // 2) Mark all objects directly reachable from strong CLDs. - template - class G1CLDClosure : public CLDClosure { - G1ParCopyClosure* _oop_closure; - G1ParCopyClosure _oop_in_klass_closure; - G1KlassScanClosure _klass_in_cld_closure; - bool _claim; - - public: - G1CLDClosure(G1ParCopyClosure* oop_closure, - bool only_young, bool claim) - : _oop_closure(oop_closure), - _oop_in_klass_closure(oop_closure->g1(), - oop_closure->pss(), - oop_closure->rp()), - _klass_in_cld_closure(&_oop_in_klass_closure, only_young), - _claim(claim) { - - } - - void do_cld(ClassLoaderData* cld) { - cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); - } - }; - - void work(uint worker_id) { - if (worker_id >= _n_workers) return; // no work needed this round - - _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); - - { - ResourceMark rm; - HandleMark hm; - - ReferenceProcessor* rp = _g1h->ref_processor_stw(); - - G1ParScanThreadState pss(_g1h, worker_id, rp); - G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); - - pss.set_evac_failure_closure(&evac_failure_cl); - - bool only_young = _g1h->g1_policy()->gcs_are_young(); - - // Non-IM young GC. - G1ParCopyClosure scan_only_root_cl(_g1h, &pss, rp); - G1CLDClosure scan_only_cld_cl(&scan_only_root_cl, - only_young, // Only process dirty klasses. - false); // No need to claim CLDs. - // IM young GC. - // Strong roots closures. - G1ParCopyClosure scan_mark_root_cl(_g1h, &pss, rp); - G1CLDClosure scan_mark_cld_cl(&scan_mark_root_cl, - false, // Process all klasses. - true); // Need to claim CLDs. - // Weak roots closures. - G1ParCopyClosure scan_mark_weak_root_cl(_g1h, &pss, rp); - G1CLDClosure scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, - false, // Process all klasses. - true); // Need to claim CLDs. - - OopClosure* strong_root_cl; - OopClosure* weak_root_cl; - CLDClosure* strong_cld_cl; - CLDClosure* weak_cld_cl; - - bool trace_metadata = false; - - if (_g1h->g1_policy()->during_initial_mark_pause()) { - // We also need to mark copied objects. - strong_root_cl = &scan_mark_root_cl; - strong_cld_cl = &scan_mark_cld_cl; - if (ClassUnloadingWithConcurrentMark) { - weak_root_cl = &scan_mark_weak_root_cl; - weak_cld_cl = &scan_mark_weak_cld_cl; - trace_metadata = true; - } else { - weak_root_cl = &scan_mark_root_cl; - weak_cld_cl = &scan_mark_cld_cl; - } - } else { - strong_root_cl = &scan_only_root_cl; - weak_root_cl = &scan_only_root_cl; - strong_cld_cl = &scan_only_cld_cl; - weak_cld_cl = &scan_only_cld_cl; - } - - pss.start_strong_roots(); - - _root_processor->evacuate_roots(strong_root_cl, - weak_root_cl, - strong_cld_cl, - weak_cld_cl, - trace_metadata, - worker_id); - - G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); - _root_processor->scan_remembered_sets(&push_heap_rs_cl, - weak_root_cl, - worker_id); - pss.end_strong_roots(); - - { - double start = os::elapsedTime(); - G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); - evac.do_void(); - double elapsed_sec = os::elapsedTime() - start; - double term_sec = pss.term_time(); - _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); - _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); - _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); - } - _g1h->g1_policy()->record_thread_age_table(pss.age_table()); - _g1h->update_surviving_young_words(pss.surviving_young_words()+1); - - if (PrintTerminationStats) { - MutexLocker x(stats_lock()); - pss.print_termination_stats(worker_id); - } - - assert(pss.queue_is_empty(), "should be empty"); - - // Close the inner scope so that the ResourceMark and HandleMark - // destructors are executed here and are included as part of the - // "GC Worker Time". - } - _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); - } -}; - -class G1StringSymbolTableUnlinkTask : public AbstractGangTask { -private: - BoolObjectClosure* _is_alive; - int _initial_string_table_size; - int _initial_symbol_table_size; - - bool _process_strings; - int _strings_processed; - int _strings_removed; - - bool _process_symbols; - int _symbols_processed; - int _symbols_removed; - -public: - G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : - AbstractGangTask("String/Symbol Unlinking"), - _is_alive(is_alive), - _process_strings(process_strings), _strings_processed(0), _strings_removed(0), - _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { - - _initial_string_table_size = StringTable::the_table()->table_size(); - _initial_symbol_table_size = SymbolTable::the_table()->table_size(); - if (process_strings) { - StringTable::clear_parallel_claimed_index(); - } - if (process_symbols) { - SymbolTable::clear_parallel_claimed_index(); - } - } - - ~G1StringSymbolTableUnlinkTask() { - guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, - err_msg("claim value %d after unlink less than initial string table size %d", - StringTable::parallel_claimed_index(), _initial_string_table_size)); - guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, - err_msg("claim value %d after unlink less than initial symbol table size %d", - SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); - - if (G1TraceStringSymbolTableScrubbing) { - gclog_or_tty->print_cr("Cleaned string and symbol table, " - "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " - "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", - strings_processed(), strings_removed(), - symbols_processed(), symbols_removed()); - } - } - - void work(uint worker_id) { - int strings_processed = 0; - int strings_removed = 0; - int symbols_processed = 0; - int symbols_removed = 0; - if (_process_strings) { - StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); - Atomic::add(strings_processed, &_strings_processed); - Atomic::add(strings_removed, &_strings_removed); - } - if (_process_symbols) { - SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); - Atomic::add(symbols_processed, &_symbols_processed); - Atomic::add(symbols_removed, &_symbols_removed); - } - } - - size_t strings_processed() const { return (size_t)_strings_processed; } - size_t strings_removed() const { return (size_t)_strings_removed; } - - size_t symbols_processed() const { return (size_t)_symbols_processed; } - size_t symbols_removed() const { return (size_t)_symbols_removed; } -}; - -class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { -private: - static Monitor* _lock; - - BoolObjectClosure* const _is_alive; - const bool _unloading_occurred; - const uint _num_workers; - - // Variables used to claim nmethods. - nmethod* _first_nmethod; - volatile nmethod* _claimed_nmethod; - - // The list of nmethods that need to be processed by the second pass. - volatile nmethod* _postponed_list; - volatile uint _num_entered_barrier; - - public: - G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : - _is_alive(is_alive), - _unloading_occurred(unloading_occurred), - _num_workers(num_workers), - _first_nmethod(NULL), - _claimed_nmethod(NULL), - _postponed_list(NULL), - _num_entered_barrier(0) - { - nmethod::increase_unloading_clock(); - // Get first alive nmethod - NMethodIterator iter = NMethodIterator(); - if(iter.next_alive()) { - _first_nmethod = iter.method(); - } - _claimed_nmethod = (volatile nmethod*)_first_nmethod; - } - - ~G1CodeCacheUnloadingTask() { - CodeCache::verify_clean_inline_caches(); - - CodeCache::set_needs_cache_clean(false); - guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); - - CodeCache::verify_icholder_relocations(); - } - - private: - void add_to_postponed_list(nmethod* nm) { - nmethod* old; - do { - old = (nmethod*)_postponed_list; - nm->set_unloading_next(old); - } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); - } - - void clean_nmethod(nmethod* nm) { - bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); - - if (postponed) { - // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. - add_to_postponed_list(nm); - } - - // Mark that this thread has been cleaned/unloaded. - // After this call, it will be safe to ask if this nmethod was unloaded or not. - nm->set_unloading_clock(nmethod::global_unloading_clock()); - } - - void clean_nmethod_postponed(nmethod* nm) { - nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); - } - - static const int MaxClaimNmethods = 16; - - void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { - nmethod* first; - NMethodIterator last; - - do { - *num_claimed_nmethods = 0; - - first = (nmethod*)_claimed_nmethod; - last = NMethodIterator(first); - - if (first != NULL) { - - for (int i = 0; i < MaxClaimNmethods; i++) { - if (!last.next_alive()) { - break; - } - claimed_nmethods[i] = last.method(); - (*num_claimed_nmethods)++; - } - } - - } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); - } - - nmethod* claim_postponed_nmethod() { - nmethod* claim; - nmethod* next; - - do { - claim = (nmethod*)_postponed_list; - if (claim == NULL) { - return NULL; - } - - next = claim->unloading_next(); - - } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); - - return claim; - } - - public: - // Mark that we're done with the first pass of nmethod cleaning. - void barrier_mark(uint worker_id) { - MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); - _num_entered_barrier++; - if (_num_entered_barrier == _num_workers) { - ml.notify_all(); - } - } - - // See if we have to wait for the other workers to - // finish their first-pass nmethod cleaning work. - void barrier_wait(uint worker_id) { - if (_num_entered_barrier < _num_workers) { - MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); - while (_num_entered_barrier < _num_workers) { - ml.wait(Mutex::_no_safepoint_check_flag, 0, false); - } - } - } - - // Cleaning and unloading of nmethods. Some work has to be postponed - // to the second pass, when we know which nmethods survive. - void work_first_pass(uint worker_id) { - // The first nmethods is claimed by the first worker. - if (worker_id == 0 && _first_nmethod != NULL) { - clean_nmethod(_first_nmethod); - _first_nmethod = NULL; - } - - int num_claimed_nmethods; - nmethod* claimed_nmethods[MaxClaimNmethods]; - - while (true) { - claim_nmethods(claimed_nmethods, &num_claimed_nmethods); - - if (num_claimed_nmethods == 0) { - break; - } - - for (int i = 0; i < num_claimed_nmethods; i++) { - clean_nmethod(claimed_nmethods[i]); - } - } - } - - void work_second_pass(uint worker_id) { - nmethod* nm; - // Take care of postponed nmethods. - while ((nm = claim_postponed_nmethod()) != NULL) { - clean_nmethod_postponed(nm); - } - } -}; - -Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); - -class G1KlassCleaningTask : public StackObj { - BoolObjectClosure* _is_alive; - volatile jint _clean_klass_tree_claimed; - ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; - - public: - G1KlassCleaningTask(BoolObjectClosure* is_alive) : - _is_alive(is_alive), - _clean_klass_tree_claimed(0), - _klass_iterator() { - } - - private: - bool claim_clean_klass_tree_task() { - if (_clean_klass_tree_claimed) { - return false; - } - - return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; - } - - InstanceKlass* claim_next_klass() { - Klass* klass; - do { - klass =_klass_iterator.next_klass(); - } while (klass != NULL && !klass->oop_is_instance()); - - return (InstanceKlass*)klass; - } - -public: - - void clean_klass(InstanceKlass* ik) { - ik->clean_implementors_list(_is_alive); - ik->clean_method_data(_is_alive); - - // G1 specific cleanup work that has - // been moved here to be done in parallel. - ik->clean_dependent_nmethods(); - } - - void work() { - ResourceMark rm; - - // One worker will clean the subklass/sibling klass tree. - if (claim_clean_klass_tree_task()) { - Klass::clean_subklass_tree(_is_alive); - } - - // All workers will help cleaning the classes, - InstanceKlass* klass; - while ((klass = claim_next_klass()) != NULL) { - clean_klass(klass); - } - } -}; - -// To minimize the remark pause times, the tasks below are done in parallel. -class G1ParallelCleaningTask : public AbstractGangTask { -private: - G1StringSymbolTableUnlinkTask _string_symbol_task; - G1CodeCacheUnloadingTask _code_cache_task; - G1KlassCleaningTask _klass_cleaning_task; - -public: - // The constructor is run in the VMThread. - G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : - AbstractGangTask("Parallel Cleaning"), - _string_symbol_task(is_alive, process_strings, process_symbols), - _code_cache_task(num_workers, is_alive, unloading_occurred), - _klass_cleaning_task(is_alive) { - } - - // The parallel work done by all worker threads. - void work(uint worker_id) { - // Do first pass of code cache cleaning. - _code_cache_task.work_first_pass(worker_id); - - // Let the threads mark that the first pass is done. - _code_cache_task.barrier_mark(worker_id); - - // Clean the Strings and Symbols. - _string_symbol_task.work(worker_id); - - // Wait for all workers to finish the first code cache cleaning pass. - _code_cache_task.barrier_wait(worker_id); - - // Do the second code cache cleaning work, which realize on - // the liveness information gathered during the first pass. - _code_cache_task.work_second_pass(worker_id); - - // Clean all klasses that were not unloaded. - _klass_cleaning_task.work(); - } -}; - - -void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, - bool process_strings, - bool process_symbols, - bool class_unloading_occurred) { - uint n_workers = workers()->active_workers(); - - G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, - n_workers, class_unloading_occurred); - set_par_threads(n_workers); - workers()->run_task(&g1_unlink_task); - set_par_threads(0); -} - -void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, - bool process_strings, bool process_symbols) { - { - uint n_workers = workers()->active_workers(); - G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); - set_par_threads(n_workers); - workers()->run_task(&g1_unlink_task); - set_par_threads(0); - } - - if (G1StringDedup::is_enabled()) { - G1StringDedup::unlink(is_alive); - } -} - -class G1RedirtyLoggedCardsTask : public AbstractGangTask { - private: - DirtyCardQueueSet* _queue; - public: - G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } - - virtual void work(uint worker_id) { - G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); - G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); - - RedirtyLoggedCardTableEntryClosure cl; - _queue->par_apply_closure_to_all_completed_buffers(&cl); - - phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); - } -}; - -void G1CollectedHeap::redirty_logged_cards() { - double redirty_logged_cards_start = os::elapsedTime(); - - uint n_workers = workers()->active_workers(); - - G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); - dirty_card_queue_set().reset_for_par_iteration(); - set_par_threads(n_workers); - workers()->run_task(&redirty_task); - set_par_threads(0); - - DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); - dcq.merge_bufferlists(&dirty_card_queue_set()); - assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); - - g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); -} - -// Weak Reference Processing support - -// An always "is_alive" closure that is used to preserve referents. -// If the object is non-null then it's alive. Used in the preservation -// of referent objects that are pointed to by reference objects -// discovered by the CM ref processor. -class G1AlwaysAliveClosure: public BoolObjectClosure { - G1CollectedHeap* _g1; -public: - G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} - bool do_object_b(oop p) { - if (p != NULL) { - return true; - } - return false; - } -}; - -bool G1STWIsAliveClosure::do_object_b(oop p) { - // An object is reachable if it is outside the collection set, - // or is inside and copied. - return !_g1->obj_in_cs(p) || p->is_forwarded(); -} - -// Non Copying Keep Alive closure -class G1KeepAliveClosure: public OopClosure { - G1CollectedHeap* _g1; -public: - G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} - void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } - void do_oop(oop* p) { - oop obj = *p; - assert(obj != NULL, "the caller should have filtered out NULL values"); - - const InCSetState cset_state = _g1->in_cset_state(obj); - if (!cset_state.is_in_cset_or_humongous()) { - return; - } - if (cset_state.is_in_cset()) { - assert( obj->is_forwarded(), "invariant" ); - *p = obj->forwardee(); - } else { - assert(!obj->is_forwarded(), "invariant" ); - assert(cset_state.is_humongous(), - err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); - _g1->set_humongous_is_live(obj); - } - } -}; - -// Copying Keep Alive closure - can be called from both -// serial and parallel code as long as different worker -// threads utilize different G1ParScanThreadState instances -// and different queues. - -class G1CopyingKeepAliveClosure: public OopClosure { - G1CollectedHeap* _g1h; - OopClosure* _copy_non_heap_obj_cl; - G1ParScanThreadState* _par_scan_state; - -public: - G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, - OopClosure* non_heap_obj_cl, - G1ParScanThreadState* pss): - _g1h(g1h), - _copy_non_heap_obj_cl(non_heap_obj_cl), - _par_scan_state(pss) - {} - - virtual void do_oop(narrowOop* p) { do_oop_work(p); } - virtual void do_oop( oop* p) { do_oop_work(p); } - - template void do_oop_work(T* p) { - oop obj = oopDesc::load_decode_heap_oop(p); - - if (_g1h->is_in_cset_or_humongous(obj)) { - // If the referent object has been forwarded (either copied - // to a new location or to itself in the event of an - // evacuation failure) then we need to update the reference - // field and, if both reference and referent are in the G1 - // heap, update the RSet for the referent. - // - // If the referent has not been forwarded then we have to keep - // it alive by policy. Therefore we have copy the referent. - // - // If the reference field is in the G1 heap then we can push - // on the PSS queue. When the queue is drained (after each - // phase of reference processing) the object and it's followers - // will be copied, the reference field set to point to the - // new location, and the RSet updated. Otherwise we need to - // use the the non-heap or metadata closures directly to copy - // the referent object and update the pointer, while avoiding - // updating the RSet. - - if (_g1h->is_in_g1_reserved(p)) { - _par_scan_state->push_on_queue(p); - } else { - assert(!Metaspace::contains((const void*)p), - err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); - _copy_non_heap_obj_cl->do_oop(p); - } - } - } -}; - -// Serial drain queue closure. Called as the 'complete_gc' -// closure for each discovered list in some of the -// reference processing phases. - -class G1STWDrainQueueClosure: public VoidClosure { -protected: - G1CollectedHeap* _g1h; - G1ParScanThreadState* _par_scan_state; - - G1ParScanThreadState* par_scan_state() { return _par_scan_state; } - -public: - G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : - _g1h(g1h), - _par_scan_state(pss) - { } - - void do_void() { - G1ParScanThreadState* const pss = par_scan_state(); - pss->trim_queue(); - } -}; - -// Parallel Reference Processing closures - -// Implementation of AbstractRefProcTaskExecutor for parallel reference -// processing during G1 evacuation pauses. - -class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { -private: - G1CollectedHeap* _g1h; - RefToScanQueueSet* _queues; - FlexibleWorkGang* _workers; - uint _active_workers; - -public: - G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, - FlexibleWorkGang* workers, - RefToScanQueueSet *task_queues, - uint n_workers) : - _g1h(g1h), - _queues(task_queues), - _workers(workers), - _active_workers(n_workers) - { - assert(n_workers > 0, "shouldn't call this otherwise"); - } - - // Executes the given task using concurrent marking worker threads. - virtual void execute(ProcessTask& task); - virtual void execute(EnqueueTask& task); -}; - -// Gang task for possibly parallel reference processing - -class G1STWRefProcTaskProxy: public AbstractGangTask { - typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; - ProcessTask& _proc_task; - G1CollectedHeap* _g1h; - RefToScanQueueSet *_task_queues; - ParallelTaskTerminator* _terminator; - -public: - G1STWRefProcTaskProxy(ProcessTask& proc_task, - G1CollectedHeap* g1h, - RefToScanQueueSet *task_queues, - ParallelTaskTerminator* terminator) : - AbstractGangTask("Process reference objects in parallel"), - _proc_task(proc_task), - _g1h(g1h), - _task_queues(task_queues), - _terminator(terminator) - {} - - virtual void work(uint worker_id) { - // The reference processing task executed by a single worker. - ResourceMark rm; - HandleMark hm; - - G1STWIsAliveClosure is_alive(_g1h); - - G1ParScanThreadState pss(_g1h, worker_id, NULL); - G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); - - pss.set_evac_failure_closure(&evac_failure_cl); - - G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); - - G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); - - OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; - - if (_g1h->g1_policy()->during_initial_mark_pause()) { - // We also need to mark copied objects. - copy_non_heap_cl = ©_mark_non_heap_cl; - } - - // Keep alive closure. - G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); - - // Complete GC closure - G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); - - // Call the reference processing task's work routine. - _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); - - // Note we cannot assert that the refs array is empty here as not all - // of the processing tasks (specifically phase2 - pp2_work) execute - // the complete_gc closure (which ordinarily would drain the queue) so - // the queue may not be empty. - } -}; - -// Driver routine for parallel reference processing. -// Creates an instance of the ref processing gang -// task and has the worker threads execute it. -void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { - assert(_workers != NULL, "Need parallel worker threads."); - - ParallelTaskTerminator terminator(_active_workers, _queues); - G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); - - _g1h->set_par_threads(_active_workers); - _workers->run_task(&proc_task_proxy); - _g1h->set_par_threads(0); -} - -// Gang task for parallel reference enqueueing. - -class G1STWRefEnqueueTaskProxy: public AbstractGangTask { - typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; - EnqueueTask& _enq_task; - -public: - G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : - AbstractGangTask("Enqueue reference objects in parallel"), - _enq_task(enq_task) - { } - - virtual void work(uint worker_id) { - _enq_task.work(worker_id); - } -}; - -// Driver routine for parallel reference enqueueing. -// Creates an instance of the ref enqueueing gang -// task and has the worker threads execute it. - -void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { - assert(_workers != NULL, "Need parallel worker threads."); - - G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); - - _g1h->set_par_threads(_active_workers); - _workers->run_task(&enq_task_proxy); - _g1h->set_par_threads(0); -} - -// End of weak reference support closures - -// Abstract task used to preserve (i.e. copy) any referent objects -// that are in the collection set and are pointed to by reference -// objects discovered by the CM ref processor. - -class G1ParPreserveCMReferentsTask: public AbstractGangTask { -protected: - G1CollectedHeap* _g1h; - RefToScanQueueSet *_queues; - ParallelTaskTerminator _terminator; - uint _n_workers; - -public: - G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) : - AbstractGangTask("ParPreserveCMReferents"), - _g1h(g1h), - _queues(task_queues), - _terminator(workers, _queues), - _n_workers(workers) - { } - - void work(uint worker_id) { - ResourceMark rm; - HandleMark hm; - - G1ParScanThreadState pss(_g1h, worker_id, NULL); - G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); - - pss.set_evac_failure_closure(&evac_failure_cl); - - assert(pss.queue_is_empty(), "both queue and overflow should be empty"); - - G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); - - G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); - - OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; - - if (_g1h->g1_policy()->during_initial_mark_pause()) { - // We also need to mark copied objects. - copy_non_heap_cl = ©_mark_non_heap_cl; - } - - // Is alive closure - G1AlwaysAliveClosure always_alive(_g1h); - - // Copying keep alive closure. Applied to referent objects that need - // to be copied. - G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); - - ReferenceProcessor* rp = _g1h->ref_processor_cm(); - - uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); - uint stride = MIN2(MAX2(_n_workers, 1U), limit); - - // limit is set using max_num_q() - which was set using ParallelGCThreads. - // So this must be true - but assert just in case someone decides to - // change the worker ids. - assert(worker_id < limit, "sanity"); - assert(!rp->discovery_is_atomic(), "check this code"); - - // Select discovered lists [i, i+stride, i+2*stride,...,limit) - for (uint idx = worker_id; idx < limit; idx += stride) { - DiscoveredList& ref_list = rp->discovered_refs()[idx]; - - DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); - while (iter.has_next()) { - // Since discovery is not atomic for the CM ref processor, we - // can see some null referent objects. - iter.load_ptrs(DEBUG_ONLY(true)); - oop ref = iter.obj(); - - // This will filter nulls. - if (iter.is_referent_alive()) { - iter.make_referent_alive(); - } - iter.move_to_next(); - } - } - - // Drain the queue - which may cause stealing - G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); - drain_queue.do_void(); - // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure - assert(pss.queue_is_empty(), "should be"); - } -}; - -// Weak Reference processing during an evacuation pause (part 1). -void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { - double ref_proc_start = os::elapsedTime(); - - ReferenceProcessor* rp = _ref_processor_stw; - assert(rp->discovery_enabled(), "should have been enabled"); - - // Any reference objects, in the collection set, that were 'discovered' - // by the CM ref processor should have already been copied (either by - // applying the external root copy closure to the discovered lists, or - // by following an RSet entry). - // - // But some of the referents, that are in the collection set, that these - // reference objects point to may not have been copied: the STW ref - // processor would have seen that the reference object had already - // been 'discovered' and would have skipped discovering the reference, - // but would not have treated the reference object as a regular oop. - // As a result the copy closure would not have been applied to the - // referent object. - // - // We need to explicitly copy these referent objects - the references - // will be processed at the end of remarking. - // - // We also need to do this copying before we process the reference - // objects discovered by the STW ref processor in case one of these - // referents points to another object which is also referenced by an - // object discovered by the STW ref processor. - - assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); - - set_par_threads(no_of_gc_workers); - G1ParPreserveCMReferentsTask keep_cm_referents(this, - no_of_gc_workers, - _task_queues); - - workers()->run_task(&keep_cm_referents); - - set_par_threads(0); - - // Closure to test whether a referent is alive. - G1STWIsAliveClosure is_alive(this); - - // Even when parallel reference processing is enabled, the processing - // of JNI refs is serial and performed serially by the current thread - // rather than by a worker. The following PSS will be used for processing - // JNI refs. - - // Use only a single queue for this PSS. - G1ParScanThreadState pss(this, 0, NULL); - - // We do not embed a reference processor in the copying/scanning - // closures while we're actually processing the discovered - // reference objects. - G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); - - pss.set_evac_failure_closure(&evac_failure_cl); - - assert(pss.queue_is_empty(), "pre-condition"); - - G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); - - G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); - - OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; - - if (g1_policy()->during_initial_mark_pause()) { - // We also need to mark copied objects. - copy_non_heap_cl = ©_mark_non_heap_cl; - } - - // Keep alive closure. - G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); - - // Serial Complete GC closure - G1STWDrainQueueClosure drain_queue(this, &pss); - - // Setup the soft refs policy... - rp->setup_policy(false); - - ReferenceProcessorStats stats; - if (!rp->processing_is_mt()) { - // Serial reference processing... - stats = rp->process_discovered_references(&is_alive, - &keep_alive, - &drain_queue, - NULL, - _gc_timer_stw, - _gc_tracer_stw->gc_id()); - } else { - // Parallel reference processing - assert(rp->num_q() == no_of_gc_workers, "sanity"); - assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); - - G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); - stats = rp->process_discovered_references(&is_alive, - &keep_alive, - &drain_queue, - &par_task_executor, - _gc_timer_stw, - _gc_tracer_stw->gc_id()); - } - - _gc_tracer_stw->report_gc_reference_stats(stats); - - // We have completed copying any necessary live referent objects. - assert(pss.queue_is_empty(), "both queue and overflow should be empty"); - - double ref_proc_time = os::elapsedTime() - ref_proc_start; - g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); -} - -// Weak Reference processing during an evacuation pause (part 2). -void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { - double ref_enq_start = os::elapsedTime(); - - ReferenceProcessor* rp = _ref_processor_stw; - assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); - - // Now enqueue any remaining on the discovered lists on to - // the pending list. - if (!rp->processing_is_mt()) { - // Serial reference processing... - rp->enqueue_discovered_references(); - } else { - // Parallel reference enqueueing - - assert(no_of_gc_workers == workers()->active_workers(), - "Need to reset active workers"); - assert(rp->num_q() == no_of_gc_workers, "sanity"); - assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); - - G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); - rp->enqueue_discovered_references(&par_task_executor); - } - - rp->verify_no_references_recorded(); - assert(!rp->discovery_enabled(), "should have been disabled"); - - // FIXME - // CM's reference processing also cleans up the string and symbol tables. - // Should we do that here also? We could, but it is a serial operation - // and could significantly increase the pause time. - - double ref_enq_time = os::elapsedTime() - ref_enq_start; - g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); -} - -void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { - _expand_heap_after_alloc_failure = true; - _evacuation_failed = false; - - // Should G1EvacuationFailureALot be in effect for this GC? - NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) - - g1_rem_set()->prepare_for_oops_into_collection_set_do(); - - // Disable the hot card cache. - G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); - hot_card_cache->reset_hot_cache_claimed_index(); - hot_card_cache->set_use_cache(false); - - const uint n_workers = workers()->active_workers(); - assert(UseDynamicNumberOfGCThreads || - n_workers == workers()->total_workers(), - "If not dynamic should be using all the workers"); - set_par_threads(n_workers); - - - init_for_evac_failure(NULL); - - assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); - double start_par_time_sec = os::elapsedTime(); - double end_par_time_sec; - - { - G1RootProcessor root_processor(this); - G1ParTask g1_par_task(this, _task_queues, &root_processor); - // InitialMark needs claim bits to keep track of the marked-through CLDs. - if (g1_policy()->during_initial_mark_pause()) { - ClassLoaderDataGraph::clear_claimed_marks(); - } - - // The individual threads will set their evac-failure closures. - if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); - // These tasks use ShareHeap::_process_strong_tasks - assert(UseDynamicNumberOfGCThreads || - workers()->active_workers() == workers()->total_workers(), - "If not dynamic should be using all the workers"); - workers()->run_task(&g1_par_task); - end_par_time_sec = os::elapsedTime(); - - // Closing the inner scope will execute the destructor - // for the G1RootProcessor object. We record the current - // elapsed time before closing the scope so that time - // taken for the destructor is NOT included in the - // reported parallel time. - } - - G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); - - double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; - phase_times->record_par_time(par_time_ms); - - double code_root_fixup_time_ms = - (os::elapsedTime() - end_par_time_sec) * 1000.0; - phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); - - set_par_threads(0); - - // Process any discovered reference objects - we have - // to do this _before_ we retire the GC alloc regions - // as we may have to copy some 'reachable' referent - // objects (and their reachable sub-graphs) that were - // not copied during the pause. - process_discovered_references(n_workers); - - if (G1StringDedup::is_enabled()) { - double fixup_start = os::elapsedTime(); - - G1STWIsAliveClosure is_alive(this); - G1KeepAliveClosure keep_alive(this); - G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); - - double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; - phase_times->record_string_dedup_fixup_time(fixup_time_ms); - } - - _allocator->release_gc_alloc_regions(n_workers, evacuation_info); - g1_rem_set()->cleanup_after_oops_into_collection_set_do(); - - // Reset and re-enable the hot card cache. - // Note the counts for the cards in the regions in the - // collection set are reset when the collection set is freed. - hot_card_cache->reset_hot_cache(); - hot_card_cache->set_use_cache(true); - - purge_code_root_memory(); - - finalize_for_evac_failure(); - - if (evacuation_failed()) { - remove_self_forwarding_pointers(); - - // Reset the G1EvacuationFailureALot counters and flags - // Note: the values are reset only when an actual - // evacuation failure occurs. - NOT_PRODUCT(reset_evacuation_should_fail();) - } - - // Enqueue any remaining references remaining on the STW - // reference processor's discovered lists. We need to do - // this after the card table is cleaned (and verified) as - // the act of enqueueing entries on to the pending list - // will log these updates (and dirty their associated - // cards). We need these updates logged to update any - // RSets. - enqueue_discovered_references(n_workers); - - redirty_logged_cards(); - COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); -} - -void G1CollectedHeap::free_region(HeapRegion* hr, - FreeRegionList* free_list, - bool par, - bool locked) { - assert(!hr->is_free(), "the region should not be free"); - assert(!hr->is_empty(), "the region should not be empty"); - assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); - assert(free_list != NULL, "pre-condition"); - - if (G1VerifyBitmaps) { - MemRegion mr(hr->bottom(), hr->end()); - concurrent_mark()->clearRangePrevBitmap(mr); - } - - // Clear the card counts for this region. - // Note: we only need to do this if the region is not young - // (since we don't refine cards in young regions). - if (!hr->is_young()) { - _cg1r->hot_card_cache()->reset_card_counts(hr); - } - hr->hr_clear(par, true /* clear_space */, locked /* locked */); - free_list->add_ordered(hr); -} - -void G1CollectedHeap::free_humongous_region(HeapRegion* hr, - FreeRegionList* free_list, - bool par) { - assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); - assert(free_list != NULL, "pre-condition"); - - size_t hr_capacity = hr->capacity(); - // We need to read this before we make the region non-humongous, - // otherwise the information will be gone. - uint last_index = hr->last_hc_index(); - hr->clear_humongous(); - free_region(hr, free_list, par); - - uint i = hr->hrm_index() + 1; - while (i < last_index) { - HeapRegion* curr_hr = region_at(i); - assert(curr_hr->is_continues_humongous(), "invariant"); - curr_hr->clear_humongous(); - free_region(curr_hr, free_list, par); - i += 1; - } -} - -void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, - const HeapRegionSetCount& humongous_regions_removed) { - if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { - MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); - _old_set.bulk_remove(old_regions_removed); - _humongous_set.bulk_remove(humongous_regions_removed); - } - -} - -void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { - assert(list != NULL, "list can't be null"); - if (!list->is_empty()) { - MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); - _hrm.insert_list_into_free_list(list); - } -} - -void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { - _allocator->decrease_used(bytes); -} - -class G1ParCleanupCTTask : public AbstractGangTask { - G1SATBCardTableModRefBS* _ct_bs; - G1CollectedHeap* _g1h; - HeapRegion* volatile _su_head; -public: - G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, - G1CollectedHeap* g1h) : - AbstractGangTask("G1 Par Cleanup CT Task"), - _ct_bs(ct_bs), _g1h(g1h) { } - - void work(uint worker_id) { - HeapRegion* r; - while (r = _g1h->pop_dirty_cards_region()) { - clear_cards(r); - } - } - - void clear_cards(HeapRegion* r) { - // Cards of the survivors should have already been dirtied. - if (!r->is_survivor()) { - _ct_bs->clear(MemRegion(r->bottom(), r->end())); - } - } -}; - -#ifndef PRODUCT -class G1VerifyCardTableCleanup: public HeapRegionClosure { - G1CollectedHeap* _g1h; - G1SATBCardTableModRefBS* _ct_bs; -public: - G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) - : _g1h(g1h), _ct_bs(ct_bs) { } - virtual bool doHeapRegion(HeapRegion* r) { - if (r->is_survivor()) { - _g1h->verify_dirty_region(r); - } else { - _g1h->verify_not_dirty_region(r); - } - return false; - } -}; - -void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { - // All of the region should be clean. - G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); - MemRegion mr(hr->bottom(), hr->end()); - ct_bs->verify_not_dirty_region(mr); -} - -void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { - // We cannot guarantee that [bottom(),end()] is dirty. Threads - // dirty allocated blocks as they allocate them. The thread that - // retires each region and replaces it with a new one will do a - // maximal allocation to fill in [pre_dummy_top(),end()] but will - // not dirty that area (one less thing to have to do while holding - // a lock). So we can only verify that [bottom(),pre_dummy_top()] - // is dirty. - G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); - MemRegion mr(hr->bottom(), hr->pre_dummy_top()); - if (hr->is_young()) { - ct_bs->verify_g1_young_region(mr); - } else { - ct_bs->verify_dirty_region(mr); - } -} - -void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { - G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); - for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { - verify_dirty_region(hr); - } -} - -void G1CollectedHeap::verify_dirty_young_regions() { - verify_dirty_young_list(_young_list->first_region()); -} - -bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, - HeapWord* tams, HeapWord* end) { - guarantee(tams <= end, - err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end))); - HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); - if (result < end) { - gclog_or_tty->cr(); - gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, - bitmap_name, p2i(result)); - gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, - bitmap_name, p2i(tams), p2i(end)); - return false; - } - return true; -} - -bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { - CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); - CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); - - HeapWord* bottom = hr->bottom(); - HeapWord* ptams = hr->prev_top_at_mark_start(); - HeapWord* ntams = hr->next_top_at_mark_start(); - HeapWord* end = hr->end(); - - bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); - - bool res_n = true; - // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window - // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap - // if we happen to be in that state. - if (mark_in_progress() || !_cmThread->in_progress()) { - res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); - } - if (!res_p || !res_n) { - gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, - HR_FORMAT_PARAMS(hr)); - gclog_or_tty->print_cr("#### Caller: %s", caller); - return false; - } - return true; -} - -void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { - if (!G1VerifyBitmaps) return; - - guarantee(verify_bitmaps(caller, hr), "bitmap verification"); -} - -class G1VerifyBitmapClosure : public HeapRegionClosure { -private: - const char* _caller; - G1CollectedHeap* _g1h; - bool _failures; - -public: - G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : - _caller(caller), _g1h(g1h), _failures(false) { } - - bool failures() { return _failures; } - - virtual bool doHeapRegion(HeapRegion* hr) { - if (hr->is_continues_humongous()) return false; - - bool result = _g1h->verify_bitmaps(_caller, hr); - if (!result) { - _failures = true; - } - return false; - } -}; - -void G1CollectedHeap::check_bitmaps(const char* caller) { - if (!G1VerifyBitmaps) return; - - G1VerifyBitmapClosure cl(caller, this); - heap_region_iterate(&cl); - guarantee(!cl.failures(), "bitmap verification"); -} - -class G1CheckCSetFastTableClosure : public HeapRegionClosure { - private: - bool _failures; - public: - G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } - - virtual bool doHeapRegion(HeapRegion* hr) { - uint i = hr->hrm_index(); - InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); - if (hr->is_humongous()) { - if (hr->in_collection_set()) { - gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); - _failures = true; - return true; - } - if (cset_state.is_in_cset()) { - gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); - _failures = true; - return true; - } - if (hr->is_continues_humongous() && cset_state.is_humongous()) { - gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); - _failures = true; - return true; - } - } else { - if (cset_state.is_humongous()) { - gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); - _failures = true; - return true; - } - if (hr->in_collection_set() != cset_state.is_in_cset()) { - gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", - hr->in_collection_set(), cset_state.value(), i); - _failures = true; - return true; - } - if (cset_state.is_in_cset()) { - if (hr->is_young() != (cset_state.is_young())) { - gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", - hr->is_young(), cset_state.value(), i); - _failures = true; - return true; - } - if (hr->is_old() != (cset_state.is_old())) { - gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", - hr->is_old(), cset_state.value(), i); - _failures = true; - return true; - } - } - } - return false; - } - - bool failures() const { return _failures; } -}; - -bool G1CollectedHeap::check_cset_fast_test() { - G1CheckCSetFastTableClosure cl; - _hrm.iterate(&cl); - return !cl.failures(); -} -#endif // PRODUCT - -void G1CollectedHeap::cleanUpCardTable() { - G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); - double start = os::elapsedTime(); - - { - // Iterate over the dirty cards region list. - G1ParCleanupCTTask cleanup_task(ct_bs, this); - - set_par_threads(); - workers()->run_task(&cleanup_task); - set_par_threads(0); -#ifndef PRODUCT - if (G1VerifyCTCleanup || VerifyAfterGC) { - G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); - heap_region_iterate(&cleanup_verifier); - } -#endif - } - - double elapsed = os::elapsedTime() - start; - g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); -} - -void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { - size_t pre_used = 0; - FreeRegionList local_free_list("Local List for CSet Freeing"); - - double young_time_ms = 0.0; - double non_young_time_ms = 0.0; - - // Since the collection set is a superset of the the young list, - // all we need to do to clear the young list is clear its - // head and length, and unlink any young regions in the code below - _young_list->clear(); - - G1CollectorPolicy* policy = g1_policy(); - - double start_sec = os::elapsedTime(); - bool non_young = true; - - HeapRegion* cur = cs_head; - int age_bound = -1; - size_t rs_lengths = 0; - - while (cur != NULL) { - assert(!is_on_master_free_list(cur), "sanity"); - if (non_young) { - if (cur->is_young()) { - double end_sec = os::elapsedTime(); - double elapsed_ms = (end_sec - start_sec) * 1000.0; - non_young_time_ms += elapsed_ms; - - start_sec = os::elapsedTime(); - non_young = false; - } - } else { - if (!cur->is_young()) { - double end_sec = os::elapsedTime(); - double elapsed_ms = (end_sec - start_sec) * 1000.0; - young_time_ms += elapsed_ms; - - start_sec = os::elapsedTime(); - non_young = true; - } - } - - rs_lengths += cur->rem_set()->occupied_locked(); - - HeapRegion* next = cur->next_in_collection_set(); - assert(cur->in_collection_set(), "bad CS"); - cur->set_next_in_collection_set(NULL); - clear_in_cset(cur); - - if (cur->is_young()) { - int index = cur->young_index_in_cset(); - assert(index != -1, "invariant"); - assert((uint) index < policy->young_cset_region_length(), "invariant"); - size_t words_survived = _surviving_young_words[index]; - cur->record_surv_words_in_group(words_survived); - - // At this point the we have 'popped' cur from the collection set - // (linked via next_in_collection_set()) but it is still in the - // young list (linked via next_young_region()). Clear the - // _next_young_region field. - cur->set_next_young_region(NULL); - } else { - int index = cur->young_index_in_cset(); - assert(index == -1, "invariant"); - } - - assert( (cur->is_young() && cur->young_index_in_cset() > -1) || - (!cur->is_young() && cur->young_index_in_cset() == -1), - "invariant" ); - - if (!cur->evacuation_failed()) { - MemRegion used_mr = cur->used_region(); - - // And the region is empty. - assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); - pre_used += cur->used(); - free_region(cur, &local_free_list, false /* par */, true /* locked */); - } else { - cur->uninstall_surv_rate_group(); - if (cur->is_young()) { - cur->set_young_index_in_cset(-1); - } - cur->set_evacuation_failed(false); - // The region is now considered to be old. - cur->set_old(); - _old_set.add(cur); - evacuation_info.increment_collectionset_used_after(cur->used()); - } - cur = next; - } - - evacuation_info.set_regions_freed(local_free_list.length()); - policy->record_max_rs_lengths(rs_lengths); - policy->cset_regions_freed(); - - double end_sec = os::elapsedTime(); - double elapsed_ms = (end_sec - start_sec) * 1000.0; - - if (non_young) { - non_young_time_ms += elapsed_ms; - } else { - young_time_ms += elapsed_ms; - } - - prepend_to_freelist(&local_free_list); - decrement_summary_bytes(pre_used); - policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); - policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); -} - -class G1FreeHumongousRegionClosure : public HeapRegionClosure { - private: - FreeRegionList* _free_region_list; - HeapRegionSet* _proxy_set; - HeapRegionSetCount _humongous_regions_removed; - size_t _freed_bytes; - public: - - G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : - _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { - } - - virtual bool doHeapRegion(HeapRegion* r) { - if (!r->is_starts_humongous()) { - return false; - } - - G1CollectedHeap* g1h = G1CollectedHeap::heap(); - - oop obj = (oop)r->bottom(); - CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); - - // The following checks whether the humongous object is live are sufficient. - // The main additional check (in addition to having a reference from the roots - // or the young gen) is whether the humongous object has a remembered set entry. - // - // A humongous object cannot be live if there is no remembered set for it - // because: - // - there can be no references from within humongous starts regions referencing - // the object because we never allocate other objects into them. - // (I.e. there are no intra-region references that may be missed by the - // remembered set) - // - as soon there is a remembered set entry to the humongous starts region - // (i.e. it has "escaped" to an old object) this remembered set entry will stay - // until the end of a concurrent mark. - // - // It is not required to check whether the object has been found dead by marking - // or not, in fact it would prevent reclamation within a concurrent cycle, as - // all objects allocated during that time are considered live. - // SATB marking is even more conservative than the remembered set. - // So if at this point in the collection there is no remembered set entry, - // nobody has a reference to it. - // At the start of collection we flush all refinement logs, and remembered sets - // are completely up-to-date wrt to references to the humongous object. - // - // Other implementation considerations: - // - never consider object arrays at this time because they would pose - // considerable effort for cleaning up the the remembered sets. This is - // required because stale remembered sets might reference locations that - // are currently allocated into. - uint region_idx = r->hrm_index(); - if (!g1h->is_humongous_reclaim_candidate(region_idx) || - !r->rem_set()->is_empty()) { - - if (G1TraceEagerReclaimHumongousObjects) { - gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d", - region_idx, - (size_t)obj->size() * HeapWordSize, - p2i(r->bottom()), - r->region_num(), - r->rem_set()->occupied(), - r->rem_set()->strong_code_roots_list_length(), - next_bitmap->isMarked(r->bottom()), - g1h->is_humongous_reclaim_candidate(region_idx), - obj->is_typeArray() - ); - } - - return false; - } - - guarantee(obj->is_typeArray(), - err_msg("Only eagerly reclaiming type arrays is supported, but the object " - PTR_FORMAT " is not.", - p2i(r->bottom()))); - - if (G1TraceEagerReclaimHumongousObjects) { - gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d", - region_idx, - (size_t)obj->size() * HeapWordSize, - p2i(r->bottom()), - r->region_num(), - r->rem_set()->occupied(), - r->rem_set()->strong_code_roots_list_length(), - next_bitmap->isMarked(r->bottom()), - g1h->is_humongous_reclaim_candidate(region_idx), - obj->is_typeArray() - ); - } - // Need to clear mark bit of the humongous object if already set. - if (next_bitmap->isMarked(r->bottom())) { - next_bitmap->clear(r->bottom()); - } - _freed_bytes += r->used(); - r->set_containing_set(NULL); - _humongous_regions_removed.increment(1u, r->capacity()); - g1h->free_humongous_region(r, _free_region_list, false); - - return false; - } - - HeapRegionSetCount& humongous_free_count() { - return _humongous_regions_removed; - } - - size_t bytes_freed() const { - return _freed_bytes; - } - - size_t humongous_reclaimed() const { - return _humongous_regions_removed.length(); - } -}; - -void G1CollectedHeap::eagerly_reclaim_humongous_regions() { - assert_at_safepoint(true); - - if (!G1EagerReclaimHumongousObjects || - (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { - g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); - return; - } - - double start_time = os::elapsedTime(); - - FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); - - G1FreeHumongousRegionClosure cl(&local_cleanup_list); - heap_region_iterate(&cl); - - HeapRegionSetCount empty_set; - remove_from_old_sets(empty_set, cl.humongous_free_count()); - - G1HRPrinter* hrp = hr_printer(); - if (hrp->is_active()) { - FreeRegionListIterator iter(&local_cleanup_list); - while (iter.more_available()) { - HeapRegion* hr = iter.get_next(); - hrp->cleanup(hr); - } - } - - prepend_to_freelist(&local_cleanup_list); - decrement_summary_bytes(cl.bytes_freed()); - - g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, - cl.humongous_reclaimed()); -} - -// This routine is similar to the above but does not record -// any policy statistics or update free lists; we are abandoning -// the current incremental collection set in preparation of a -// full collection. After the full GC we will start to build up -// the incremental collection set again. -// This is only called when we're doing a full collection -// and is immediately followed by the tearing down of the young list. - -void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { - HeapRegion* cur = cs_head; - - while (cur != NULL) { - HeapRegion* next = cur->next_in_collection_set(); - assert(cur->in_collection_set(), "bad CS"); - cur->set_next_in_collection_set(NULL); - clear_in_cset(cur); - cur->set_young_index_in_cset(-1); - cur = next; - } -} - -void G1CollectedHeap::set_free_regions_coming() { - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " - "setting free regions coming"); - } - - assert(!free_regions_coming(), "pre-condition"); - _free_regions_coming = true; -} - -void G1CollectedHeap::reset_free_regions_coming() { - assert(free_regions_coming(), "pre-condition"); - - { - MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); - _free_regions_coming = false; - SecondaryFreeList_lock->notify_all(); - } - - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " - "reset free regions coming"); - } -} - -void G1CollectedHeap::wait_while_free_regions_coming() { - // Most of the time we won't have to wait, so let's do a quick test - // first before we take the lock. - if (!free_regions_coming()) { - return; - } - - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " - "waiting for free regions"); - } - - { - MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); - while (free_regions_coming()) { - SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); - } - } - - if (G1ConcRegionFreeingVerbose) { - gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " - "done waiting for free regions"); - } -} - -void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { - _young_list->push_region(hr); -} - -class NoYoungRegionsClosure: public HeapRegionClosure { -private: - bool _success; -public: - NoYoungRegionsClosure() : _success(true) { } - bool doHeapRegion(HeapRegion* r) { - if (r->is_young()) { - gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", - p2i(r->bottom()), p2i(r->end())); - _success = false; - } - return false; - } - bool success() { return _success; } -}; - -bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { - bool ret = _young_list->check_list_empty(check_sample); - - if (check_heap) { - NoYoungRegionsClosure closure; - heap_region_iterate(&closure); - ret = ret && closure.success(); - } - - return ret; -} - -class TearDownRegionSetsClosure : public HeapRegionClosure { -private: - HeapRegionSet *_old_set; - -public: - TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } - - bool doHeapRegion(HeapRegion* r) { - if (r->is_old()) { - _old_set->remove(r); - } else { - // We ignore free regions, we'll empty the free list afterwards. - // We ignore young regions, we'll empty the young list afterwards. - // We ignore humongous regions, we're not tearing down the - // humongous regions set. - assert(r->is_free() || r->is_young() || r->is_humongous(), - "it cannot be another type"); - } - return false; - } - - ~TearDownRegionSetsClosure() { - assert(_old_set->is_empty(), "post-condition"); - } -}; - -void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { - assert_at_safepoint(true /* should_be_vm_thread */); - - if (!free_list_only) { - TearDownRegionSetsClosure cl(&_old_set); - heap_region_iterate(&cl); - - // Note that emptying the _young_list is postponed and instead done as - // the first step when rebuilding the regions sets again. The reason for - // this is that during a full GC string deduplication needs to know if - // a collected region was young or old when the full GC was initiated. - } - _hrm.remove_all_free_regions(); -} - -class RebuildRegionSetsClosure : public HeapRegionClosure { -private: - bool _free_list_only; - HeapRegionSet* _old_set; - HeapRegionManager* _hrm; - size_t _total_used; - -public: - RebuildRegionSetsClosure(bool free_list_only, - HeapRegionSet* old_set, HeapRegionManager* hrm) : - _free_list_only(free_list_only), - _old_set(old_set), _hrm(hrm), _total_used(0) { - assert(_hrm->num_free_regions() == 0, "pre-condition"); - if (!free_list_only) { - assert(_old_set->is_empty(), "pre-condition"); - } - } - - bool doHeapRegion(HeapRegion* r) { - if (r->is_continues_humongous()) { - return false; - } - - if (r->is_empty()) { - // Add free regions to the free list - r->set_free(); - r->set_allocation_context(AllocationContext::system()); - _hrm->insert_into_free_list(r); - } else if (!_free_list_only) { - assert(!r->is_young(), "we should not come across young regions"); - - if (r->is_humongous()) { - // We ignore humongous regions, we left the humongous set unchanged - } else { - // Objects that were compacted would have ended up on regions - // that were previously old or free. - assert(r->is_free() || r->is_old(), "invariant"); - // We now consider them old, so register as such. - r->set_old(); - _old_set->add(r); - } - _total_used += r->used(); - } - - return false; - } - - size_t total_used() { - return _total_used; - } -}; - -void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { - assert_at_safepoint(true /* should_be_vm_thread */); - - if (!free_list_only) { - _young_list->empty_list(); - } - - RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); - heap_region_iterate(&cl); - - if (!free_list_only) { - _allocator->set_used(cl.total_used()); - } - assert(_allocator->used_unlocked() == recalculate_used(), - err_msg("inconsistent _allocator->used_unlocked(), " - "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, - _allocator->used_unlocked(), recalculate_used())); -} - -void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { - _refine_cte_cl->set_concurrent(concurrent); -} - -bool G1CollectedHeap::is_in_closed_subset(const void* p) const { - HeapRegion* hr = heap_region_containing(p); - return hr->is_in(p); -} - -// Methods for the mutator alloc region - -HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, - bool force) { - assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); - assert(!force || g1_policy()->can_expand_young_list(), - "if force is true we should be able to expand the young list"); - bool young_list_full = g1_policy()->is_young_list_full(); - if (force || !young_list_full) { - HeapRegion* new_alloc_region = new_region(word_size, - false /* is_old */, - false /* do_expand */); - if (new_alloc_region != NULL) { - set_region_short_lived_locked(new_alloc_region); - _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); - check_bitmaps("Mutator Region Allocation", new_alloc_region); - return new_alloc_region; - } - } - return NULL; -} - -void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, - size_t allocated_bytes) { - assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); - assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); - - g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); - _allocator->increase_used(allocated_bytes); - _hr_printer.retire(alloc_region); - // We update the eden sizes here, when the region is retired, - // instead of when it's allocated, since this is the point that its - // used space has been recored in _summary_bytes_used. - g1mm()->update_eden_size(); -} - -void G1CollectedHeap::set_par_threads() { - // Don't change the number of workers. Use the value previously set - // in the workgroup. - uint n_workers = workers()->active_workers(); - assert(UseDynamicNumberOfGCThreads || - n_workers == workers()->total_workers(), - "Otherwise should be using the total number of workers"); - if (n_workers == 0) { - assert(false, "Should have been set in prior evacuation pause."); - n_workers = ParallelGCThreads; - workers()->set_active_workers(n_workers); - } - set_par_threads(n_workers); -} - -// Methods for the GC alloc regions - -HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, - uint count, - InCSetState dest) { - assert(FreeList_lock->owned_by_self(), "pre-condition"); - - if (count < g1_policy()->max_regions(dest)) { - const bool is_survivor = (dest.is_young()); - HeapRegion* new_alloc_region = new_region(word_size, - !is_survivor, - true /* do_expand */); - if (new_alloc_region != NULL) { - // We really only need to do this for old regions given that we - // should never scan survivors. But it doesn't hurt to do it - // for survivors too. - new_alloc_region->record_timestamp(); - if (is_survivor) { - new_alloc_region->set_survivor(); - _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); - check_bitmaps("Survivor Region Allocation", new_alloc_region); - } else { - new_alloc_region->set_old(); - _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); - check_bitmaps("Old Region Allocation", new_alloc_region); - } - bool during_im = g1_policy()->during_initial_mark_pause(); - new_alloc_region->note_start_of_copying(during_im); - return new_alloc_region; - } - } - return NULL; -} - -void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, - size_t allocated_bytes, - InCSetState dest) { - bool during_im = g1_policy()->during_initial_mark_pause(); - alloc_region->note_end_of_copying(during_im); - g1_policy()->record_bytes_copied_during_gc(allocated_bytes); - if (dest.is_young()) { - young_list()->add_survivor_region(alloc_region); - } else { - _old_set.add(alloc_region); - } - _hr_printer.retire(alloc_region); -} - -// Heap region set verification - -class VerifyRegionListsClosure : public HeapRegionClosure { -private: - HeapRegionSet* _old_set; - HeapRegionSet* _humongous_set; - HeapRegionManager* _hrm; - -public: - HeapRegionSetCount _old_count; - HeapRegionSetCount _humongous_count; - HeapRegionSetCount _free_count; - - VerifyRegionListsClosure(HeapRegionSet* old_set, - HeapRegionSet* humongous_set, - HeapRegionManager* hrm) : - _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), - _old_count(), _humongous_count(), _free_count(){ } - - bool doHeapRegion(HeapRegion* hr) { - if (hr->is_continues_humongous()) { - return false; - } - - if (hr->is_young()) { - // TODO - } else if (hr->is_starts_humongous()) { - assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); - _humongous_count.increment(1u, hr->capacity()); - } else if (hr->is_empty()) { - assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); - _free_count.increment(1u, hr->capacity()); - } else if (hr->is_old()) { - assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); - _old_count.increment(1u, hr->capacity()); - } else { - ShouldNotReachHere(); - } - return false; - } - - void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { - guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); - guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, - old_set->total_capacity_bytes(), _old_count.capacity())); - - guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); - guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, - humongous_set->total_capacity_bytes(), _humongous_count.capacity())); - - guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length())); - guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, - free_list->total_capacity_bytes(), _free_count.capacity())); - } -}; - -void G1CollectedHeap::verify_region_sets() { - assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); - - // First, check the explicit lists. - _hrm.verify(); - { - // Given that a concurrent operation might be adding regions to - // the secondary free list we have to take the lock before - // verifying it. - MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); - _secondary_free_list.verify_list(); - } - - // If a concurrent region freeing operation is in progress it will - // be difficult to correctly attributed any free regions we come - // across to the correct free list given that they might belong to - // one of several (free_list, secondary_free_list, any local lists, - // etc.). So, if that's the case we will skip the rest of the - // verification operation. Alternatively, waiting for the concurrent - // operation to complete will have a non-trivial effect on the GC's - // operation (no concurrent operation will last longer than the - // interval between two calls to verification) and it might hide - // any issues that we would like to catch during testing. - if (free_regions_coming()) { - return; - } - - // Make sure we append the secondary_free_list on the free_list so - // that all free regions we will come across can be safely - // attributed to the free_list. - append_secondary_free_list_if_not_empty_with_lock(); - - // Finally, make sure that the region accounting in the lists is - // consistent with what we see in the heap. - - VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); - heap_region_iterate(&cl); - cl.verify_counts(&_old_set, &_humongous_set, &_hrm); -} - -// Optimized nmethod scanning - -class RegisterNMethodOopClosure: public OopClosure { - G1CollectedHeap* _g1h; - nmethod* _nm; - - template void do_oop_work(T* p) { - T heap_oop = oopDesc::load_heap_oop(p); - if (!oopDesc::is_null(heap_oop)) { - oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); - HeapRegion* hr = _g1h->heap_region_containing(obj); - assert(!hr->is_continues_humongous(), - err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT - " starting at "HR_FORMAT, - p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); - - // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. - hr->add_strong_code_root_locked(_nm); - } - } - -public: - RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : - _g1h(g1h), _nm(nm) {} - - void do_oop(oop* p) { do_oop_work(p); } - void do_oop(narrowOop* p) { do_oop_work(p); } -}; - -class UnregisterNMethodOopClosure: public OopClosure { - G1CollectedHeap* _g1h; - nmethod* _nm; - - template void do_oop_work(T* p) { - T heap_oop = oopDesc::load_heap_oop(p); - if (!oopDesc::is_null(heap_oop)) { - oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); - HeapRegion* hr = _g1h->heap_region_containing(obj); - assert(!hr->is_continues_humongous(), - err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT - " starting at "HR_FORMAT, - p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); - - hr->remove_strong_code_root(_nm); - } - } - -public: - UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : - _g1h(g1h), _nm(nm) {} - - void do_oop(oop* p) { do_oop_work(p); } - void do_oop(narrowOop* p) { do_oop_work(p); } -}; - -void G1CollectedHeap::register_nmethod(nmethod* nm) { - CollectedHeap::register_nmethod(nm); - - guarantee(nm != NULL, "sanity"); - RegisterNMethodOopClosure reg_cl(this, nm); - nm->oops_do(®_cl); -} - -void G1CollectedHeap::unregister_nmethod(nmethod* nm) { - CollectedHeap::unregister_nmethod(nm); - - guarantee(nm != NULL, "sanity"); - UnregisterNMethodOopClosure reg_cl(this, nm); - nm->oops_do(®_cl, true); -} - -void G1CollectedHeap::purge_code_root_memory() { - double purge_start = os::elapsedTime(); - G1CodeRootSet::purge(); - double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; - g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); -} - -class RebuildStrongCodeRootClosure: public CodeBlobClosure { - G1CollectedHeap* _g1h; - -public: - RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : - _g1h(g1h) {} - - void do_code_blob(CodeBlob* cb) { - nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; - if (nm == NULL) { - return; - } - - if (ScavengeRootsInCode) { - _g1h->register_nmethod(nm); - } - } -}; - -void G1CollectedHeap::rebuild_strong_code_roots() { - RebuildStrongCodeRootClosure blob_cl(this); - CodeCache::blobs_do(&blob_cl); -} --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/g1/g1CollectedHeap.cpp 2015-05-13 13:55:35.525992274 +0200 @@ -0,0 +1,6575 @@ +/* + * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#include "precompiled.hpp" +#include "classfile/metadataOnStackMark.hpp" +#include "classfile/stringTable.hpp" +#include "code/codeCache.hpp" +#include "code/icBuffer.hpp" +#include "gc/g1/bufferingOopClosure.hpp" +#include "gc/g1/concurrentG1Refine.hpp" +#include "gc/g1/concurrentG1RefineThread.hpp" +#include "gc/g1/concurrentMarkThread.inline.hpp" +#include "gc/g1/g1AllocRegion.inline.hpp" +#include "gc/g1/g1CollectedHeap.inline.hpp" +#include "gc/g1/g1CollectorPolicy.hpp" +#include "gc/g1/g1ErgoVerbose.hpp" +#include "gc/g1/g1EvacFailure.hpp" +#include "gc/g1/g1GCPhaseTimes.hpp" +#include "gc/g1/g1Log.hpp" +#include "gc/g1/g1MarkSweep.hpp" +#include "gc/g1/g1OopClosures.inline.hpp" +#include "gc/g1/g1ParScanThreadState.inline.hpp" +#include "gc/g1/g1RegionToSpaceMapper.hpp" +#include "gc/g1/g1RemSet.inline.hpp" +#include "gc/g1/g1RootProcessor.hpp" +#include "gc/g1/g1StringDedup.hpp" +#include "gc/g1/g1YCTypes.hpp" +#include "gc/g1/heapRegion.inline.hpp" +#include "gc/g1/heapRegionRemSet.hpp" +#include "gc/g1/heapRegionSet.inline.hpp" +#include "gc/g1/vm_operations_g1.hpp" +#include "gc/shared/gcHeapSummary.hpp" +#include "gc/shared/gcLocker.inline.hpp" +#include "gc/shared/gcTimer.hpp" +#include "gc/shared/gcTrace.hpp" +#include "gc/shared/gcTraceTime.hpp" +#include "gc/shared/generationSpec.hpp" +#include "gc/shared/isGCActiveMark.hpp" +#include "gc/shared/referenceProcessor.hpp" +#include "gc/shared/taskqueue.inline.hpp" +#include "memory/allocation.hpp" +#include "memory/iterator.hpp" +#include "oops/oop.inline.hpp" +#include "runtime/atomic.inline.hpp" +#include "runtime/orderAccess.inline.hpp" +#include "runtime/vmThread.hpp" +#include "utilities/globalDefinitions.hpp" +#include "utilities/stack.inline.hpp" + +size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; + +// turn it on so that the contents of the young list (scan-only / +// to-be-collected) are printed at "strategic" points before / during +// / after the collection --- this is useful for debugging +#define YOUNG_LIST_VERBOSE 0 +// CURRENT STATUS +// This file is under construction. Search for "FIXME". + +// INVARIANTS/NOTES +// +// All allocation activity covered by the G1CollectedHeap interface is +// serialized by acquiring the HeapLock. This happens in mem_allocate +// and allocate_new_tlab, which are the "entry" points to the +// allocation code from the rest of the JVM. (Note that this does not +// apply to TLAB allocation, which is not part of this interface: it +// is done by clients of this interface.) + +// Local to this file. + +class RefineCardTableEntryClosure: public CardTableEntryClosure { + bool _concurrent; +public: + RefineCardTableEntryClosure() : _concurrent(true) { } + + bool do_card_ptr(jbyte* card_ptr, uint worker_i) { + bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false); + // This path is executed by the concurrent refine or mutator threads, + // concurrently, and so we do not care if card_ptr contains references + // that point into the collection set. + assert(!oops_into_cset, "should be"); + + if (_concurrent && SuspendibleThreadSet::should_yield()) { + // Caller will actually yield. + return false; + } + // Otherwise, we finished successfully; return true. + return true; + } + + void set_concurrent(bool b) { _concurrent = b; } +}; + + +class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { + private: + size_t _num_processed; + + public: + RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { } + + bool do_card_ptr(jbyte* card_ptr, uint worker_i) { + *card_ptr = CardTableModRefBS::dirty_card_val(); + _num_processed++; + return true; + } + + size_t num_processed() const { return _num_processed; } +}; + +YoungList::YoungList(G1CollectedHeap* g1h) : + _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0), + _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) { + guarantee(check_list_empty(false), "just making sure..."); +} + +void YoungList::push_region(HeapRegion *hr) { + assert(!hr->is_young(), "should not already be young"); + assert(hr->get_next_young_region() == NULL, "cause it should!"); + + hr->set_next_young_region(_head); + _head = hr; + + _g1h->g1_policy()->set_region_eden(hr, (int) _length); + ++_length; +} + +void YoungList::add_survivor_region(HeapRegion* hr) { + assert(hr->is_survivor(), "should be flagged as survivor region"); + assert(hr->get_next_young_region() == NULL, "cause it should!"); + + hr->set_next_young_region(_survivor_head); + if (_survivor_head == NULL) { + _survivor_tail = hr; + } + _survivor_head = hr; + ++_survivor_length; +} + +void YoungList::empty_list(HeapRegion* list) { + while (list != NULL) { + HeapRegion* next = list->get_next_young_region(); + list->set_next_young_region(NULL); + list->uninstall_surv_rate_group(); + // This is called before a Full GC and all the non-empty / + // non-humongous regions at the end of the Full GC will end up as + // old anyway. + list->set_old(); + list = next; + } +} + +void YoungList::empty_list() { + assert(check_list_well_formed(), "young list should be well formed"); + + empty_list(_head); + _head = NULL; + _length = 0; + + empty_list(_survivor_head); + _survivor_head = NULL; + _survivor_tail = NULL; + _survivor_length = 0; + + _last_sampled_rs_lengths = 0; + + assert(check_list_empty(false), "just making sure..."); +} + +bool YoungList::check_list_well_formed() { + bool ret = true; + + uint length = 0; + HeapRegion* curr = _head; + HeapRegion* last = NULL; + while (curr != NULL) { + if (!curr->is_young()) { + gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" " + "incorrectly tagged (y: %d, surv: %d)", + p2i(curr->bottom()), p2i(curr->end()), + curr->is_young(), curr->is_survivor()); + ret = false; + } + ++length; + last = curr; + curr = curr->get_next_young_region(); + } + ret = ret && (length == _length); + + if (!ret) { + gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!"); + gclog_or_tty->print_cr("### list has %u entries, _length is %u", + length, _length); + } + + return ret; +} + +bool YoungList::check_list_empty(bool check_sample) { + bool ret = true; + + if (_length != 0) { + gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u", + _length); + ret = false; + } + if (check_sample && _last_sampled_rs_lengths != 0) { + gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths"); + ret = false; + } + if (_head != NULL) { + gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head"); + ret = false; + } + if (!ret) { + gclog_or_tty->print_cr("### YOUNG LIST does not seem empty"); + } + + return ret; +} + +void +YoungList::rs_length_sampling_init() { + _sampled_rs_lengths = 0; + _curr = _head; +} + +bool +YoungList::rs_length_sampling_more() { + return _curr != NULL; +} + +void +YoungList::rs_length_sampling_next() { + assert( _curr != NULL, "invariant" ); + size_t rs_length = _curr->rem_set()->occupied(); + + _sampled_rs_lengths += rs_length; + + // The current region may not yet have been added to the + // incremental collection set (it gets added when it is + // retired as the current allocation region). + if (_curr->in_collection_set()) { + // Update the collection set policy information for this region + _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length); + } + + _curr = _curr->get_next_young_region(); + if (_curr == NULL) { + _last_sampled_rs_lengths = _sampled_rs_lengths; + // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths); + } +} + +void +YoungList::reset_auxilary_lists() { + guarantee( is_empty(), "young list should be empty" ); + assert(check_list_well_formed(), "young list should be well formed"); + + // Add survivor regions to SurvRateGroup. + _g1h->g1_policy()->note_start_adding_survivor_regions(); + _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */); + + int young_index_in_cset = 0; + for (HeapRegion* curr = _survivor_head; + curr != NULL; + curr = curr->get_next_young_region()) { + _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset); + + // The region is a non-empty survivor so let's add it to + // the incremental collection set for the next evacuation + // pause. + _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr); + young_index_in_cset += 1; + } + assert((uint) young_index_in_cset == _survivor_length, "post-condition"); + _g1h->g1_policy()->note_stop_adding_survivor_regions(); + + _head = _survivor_head; + _length = _survivor_length; + if (_survivor_head != NULL) { + assert(_survivor_tail != NULL, "cause it shouldn't be"); + assert(_survivor_length > 0, "invariant"); + _survivor_tail->set_next_young_region(NULL); + } + + // Don't clear the survivor list handles until the start of + // the next evacuation pause - we need it in order to re-tag + // the survivor regions from this evacuation pause as 'young' + // at the start of the next. + + _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */); + + assert(check_list_well_formed(), "young list should be well formed"); +} + +void YoungList::print() { + HeapRegion* lists[] = {_head, _survivor_head}; + const char* names[] = {"YOUNG", "SURVIVOR"}; + + for (uint list = 0; list < ARRAY_SIZE(lists); ++list) { + gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]); + HeapRegion *curr = lists[list]; + if (curr == NULL) + gclog_or_tty->print_cr(" empty"); + while (curr != NULL) { + gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d", + HR_FORMAT_PARAMS(curr), + p2i(curr->prev_top_at_mark_start()), + p2i(curr->next_top_at_mark_start()), + curr->age_in_surv_rate_group_cond()); + curr = curr->get_next_young_region(); + } + } + + gclog_or_tty->cr(); +} + +void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { + HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); +} + +void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { + // The from card cache is not the memory that is actually committed. So we cannot + // take advantage of the zero_filled parameter. + reset_from_card_cache(start_idx, num_regions); +} + +void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr) +{ + // Claim the right to put the region on the dirty cards region list + // by installing a self pointer. + HeapRegion* next = hr->get_next_dirty_cards_region(); + if (next == NULL) { + HeapRegion* res = (HeapRegion*) + Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(), + NULL); + if (res == NULL) { + HeapRegion* head; + do { + // Put the region to the dirty cards region list. + head = _dirty_cards_region_list; + next = (HeapRegion*) + Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head); + if (next == head) { + assert(hr->get_next_dirty_cards_region() == hr, + "hr->get_next_dirty_cards_region() != hr"); + if (next == NULL) { + // The last region in the list points to itself. + hr->set_next_dirty_cards_region(hr); + } else { + hr->set_next_dirty_cards_region(next); + } + } + } while (next != head); + } + } +} + +HeapRegion* G1CollectedHeap::pop_dirty_cards_region() +{ + HeapRegion* head; + HeapRegion* hr; + do { + head = _dirty_cards_region_list; + if (head == NULL) { + return NULL; + } + HeapRegion* new_head = head->get_next_dirty_cards_region(); + if (head == new_head) { + // The last region. + new_head = NULL; + } + hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list, + head); + } while (hr != head); + assert(hr != NULL, "invariant"); + hr->set_next_dirty_cards_region(NULL); + return hr; +} + +// Returns true if the reference points to an object that +// can move in an incremental collection. +bool G1CollectedHeap::is_scavengable(const void* p) { + HeapRegion* hr = heap_region_containing(p); + return !hr->is_humongous(); +} + +// Private methods. + +HeapRegion* +G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) { + MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); + while (!_secondary_free_list.is_empty() || free_regions_coming()) { + if (!_secondary_free_list.is_empty()) { + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " + "secondary_free_list has %u entries", + _secondary_free_list.length()); + } + // It looks as if there are free regions available on the + // secondary_free_list. Let's move them to the free_list and try + // again to allocate from it. + append_secondary_free_list(); + + assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not " + "empty we should have moved at least one entry to the free_list"); + HeapRegion* res = _hrm.allocate_free_region(is_old); + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " + "allocated "HR_FORMAT" from secondary_free_list", + HR_FORMAT_PARAMS(res)); + } + return res; + } + + // Wait here until we get notified either when (a) there are no + // more free regions coming or (b) some regions have been moved on + // the secondary_free_list. + SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); + } + + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " + "could not allocate from secondary_free_list"); + } + return NULL; +} + +HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { + assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, + "the only time we use this to allocate a humongous region is " + "when we are allocating a single humongous region"); + + HeapRegion* res; + if (G1StressConcRegionFreeing) { + if (!_secondary_free_list.is_empty()) { + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " + "forced to look at the secondary_free_list"); + } + res = new_region_try_secondary_free_list(is_old); + if (res != NULL) { + return res; + } + } + } + + res = _hrm.allocate_free_region(is_old); + + if (res == NULL) { + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : " + "res == NULL, trying the secondary_free_list"); + } + res = new_region_try_secondary_free_list(is_old); + } + if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { + // Currently, only attempts to allocate GC alloc regions set + // do_expand to true. So, we should only reach here during a + // safepoint. If this assumption changes we might have to + // reconsider the use of _expand_heap_after_alloc_failure. + assert(SafepointSynchronize::is_at_safepoint(), "invariant"); + + ergo_verbose1(ErgoHeapSizing, + "attempt heap expansion", + ergo_format_reason("region allocation request failed") + ergo_format_byte("allocation request"), + word_size * HeapWordSize); + if (expand(word_size * HeapWordSize)) { + // Given that expand() succeeded in expanding the heap, and we + // always expand the heap by an amount aligned to the heap + // region size, the free list should in theory not be empty. + // In either case allocate_free_region() will check for NULL. + res = _hrm.allocate_free_region(is_old); + } else { + _expand_heap_after_alloc_failure = false; + } + } + return res; +} + +HeapWord* +G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, + uint num_regions, + size_t word_size, + AllocationContext_t context) { + assert(first != G1_NO_HRM_INDEX, "pre-condition"); + assert(is_humongous(word_size), "word_size should be humongous"); + assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); + + // Index of last region in the series + 1. + uint last = first + num_regions; + + // We need to initialize the region(s) we just discovered. This is + // a bit tricky given that it can happen concurrently with + // refinement threads refining cards on these regions and + // potentially wanting to refine the BOT as they are scanning + // those cards (this can happen shortly after a cleanup; see CR + // 6991377). So we have to set up the region(s) carefully and in + // a specific order. + + // The word size sum of all the regions we will allocate. + size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; + assert(word_size <= word_size_sum, "sanity"); + + // This will be the "starts humongous" region. + HeapRegion* first_hr = region_at(first); + // The header of the new object will be placed at the bottom of + // the first region. + HeapWord* new_obj = first_hr->bottom(); + // This will be the new end of the first region in the series that + // should also match the end of the last region in the series. + HeapWord* new_end = new_obj + word_size_sum; + // This will be the new top of the first region that will reflect + // this allocation. + HeapWord* new_top = new_obj + word_size; + + // First, we need to zero the header of the space that we will be + // allocating. When we update top further down, some refinement + // threads might try to scan the region. By zeroing the header we + // ensure that any thread that will try to scan the region will + // come across the zero klass word and bail out. + // + // NOTE: It would not have been correct to have used + // CollectedHeap::fill_with_object() and make the space look like + // an int array. The thread that is doing the allocation will + // later update the object header to a potentially different array + // type and, for a very short period of time, the klass and length + // fields will be inconsistent. This could cause a refinement + // thread to calculate the object size incorrectly. + Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); + + // We will set up the first region as "starts humongous". This + // will also update the BOT covering all the regions to reflect + // that there is a single object that starts at the bottom of the + // first region. + first_hr->set_starts_humongous(new_top, new_end); + first_hr->set_allocation_context(context); + // Then, if there are any, we will set up the "continues + // humongous" regions. + HeapRegion* hr = NULL; + for (uint i = first + 1; i < last; ++i) { + hr = region_at(i); + hr->set_continues_humongous(first_hr); + hr->set_allocation_context(context); + } + // If we have "continues humongous" regions (hr != NULL), then the + // end of the last one should match new_end. + assert(hr == NULL || hr->end() == new_end, "sanity"); + + // Up to this point no concurrent thread would have been able to + // do any scanning on any region in this series. All the top + // fields still point to bottom, so the intersection between + // [bottom,top] and [card_start,card_end] will be empty. Before we + // update the top fields, we'll do a storestore to make sure that + // no thread sees the update to top before the zeroing of the + // object header and the BOT initialization. + OrderAccess::storestore(); + + // Now that the BOT and the object header have been initialized, + // we can update top of the "starts humongous" region. + assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), + "new_top should be in this region"); + first_hr->set_top(new_top); + if (_hr_printer.is_active()) { + HeapWord* bottom = first_hr->bottom(); + HeapWord* end = first_hr->orig_end(); + if ((first + 1) == last) { + // the series has a single humongous region + _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top); + } else { + // the series has more than one humongous regions + _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end); + } + } + + // Now, we will update the top fields of the "continues humongous" + // regions. The reason we need to do this is that, otherwise, + // these regions would look empty and this will confuse parts of + // G1. For example, the code that looks for a consecutive number + // of empty regions will consider them empty and try to + // re-allocate them. We can extend is_empty() to also include + // !is_continues_humongous(), but it is easier to just update the top + // fields here. The way we set top for all regions (i.e., top == + // end for all regions but the last one, top == new_top for the + // last one) is actually used when we will free up the humongous + // region in free_humongous_region(). + hr = NULL; + for (uint i = first + 1; i < last; ++i) { + hr = region_at(i); + if ((i + 1) == last) { + // last continues humongous region + assert(hr->bottom() < new_top && new_top <= hr->end(), + "new_top should fall on this region"); + hr->set_top(new_top); + _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top); + } else { + // not last one + assert(new_top > hr->end(), "new_top should be above this region"); + hr->set_top(hr->end()); + _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end()); + } + } + // If we have continues humongous regions (hr != NULL), then the + // end of the last one should match new_end and its top should + // match new_top. + assert(hr == NULL || + (hr->end() == new_end && hr->top() == new_top), "sanity"); + check_bitmaps("Humongous Region Allocation", first_hr); + + assert(first_hr->used() == word_size * HeapWordSize, "invariant"); + _allocator->increase_used(first_hr->used()); + _humongous_set.add(first_hr); + + return new_obj; +} + +// If could fit into free regions w/o expansion, try. +// Otherwise, if can expand, do so. +// Otherwise, if using ex regions might help, try with ex given back. +HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) { + assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); + + verify_region_sets_optional(); + + uint first = G1_NO_HRM_INDEX; + uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords); + + if (obj_regions == 1) { + // Only one region to allocate, try to use a fast path by directly allocating + // from the free lists. Do not try to expand here, we will potentially do that + // later. + HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); + if (hr != NULL) { + first = hr->hrm_index(); + } + } else { + // We can't allocate humongous regions spanning more than one region while + // cleanupComplete() is running, since some of the regions we find to be + // empty might not yet be added to the free list. It is not straightforward + // to know in which list they are on so that we can remove them. We only + // need to do this if we need to allocate more than one region to satisfy the + // current humongous allocation request. If we are only allocating one region + // we use the one-region region allocation code (see above), that already + // potentially waits for regions from the secondary free list. + wait_while_free_regions_coming(); + append_secondary_free_list_if_not_empty_with_lock(); + + // Policy: Try only empty regions (i.e. already committed first). Maybe we + // are lucky enough to find some. + first = _hrm.find_contiguous_only_empty(obj_regions); + if (first != G1_NO_HRM_INDEX) { + _hrm.allocate_free_regions_starting_at(first, obj_regions); + } + } + + if (first == G1_NO_HRM_INDEX) { + // Policy: We could not find enough regions for the humongous object in the + // free list. Look through the heap to find a mix of free and uncommitted regions. + // If so, try expansion. + first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); + if (first != G1_NO_HRM_INDEX) { + // We found something. Make sure these regions are committed, i.e. expand + // the heap. Alternatively we could do a defragmentation GC. + ergo_verbose1(ErgoHeapSizing, + "attempt heap expansion", + ergo_format_reason("humongous allocation request failed") + ergo_format_byte("allocation request"), + word_size * HeapWordSize); + + _hrm.expand_at(first, obj_regions); + g1_policy()->record_new_heap_size(num_regions()); + +#ifdef ASSERT + for (uint i = first; i < first + obj_regions; ++i) { + HeapRegion* hr = region_at(i); + assert(hr->is_free(), "sanity"); + assert(hr->is_empty(), "sanity"); + assert(is_on_master_free_list(hr), "sanity"); + } +#endif + _hrm.allocate_free_regions_starting_at(first, obj_regions); + } else { + // Policy: Potentially trigger a defragmentation GC. + } + } + + HeapWord* result = NULL; + if (first != G1_NO_HRM_INDEX) { + result = humongous_obj_allocate_initialize_regions(first, obj_regions, + word_size, context); + assert(result != NULL, "it should always return a valid result"); + + // A successful humongous object allocation changes the used space + // information of the old generation so we need to recalculate the + // sizes and update the jstat counters here. + g1mm()->update_sizes(); + } + + verify_region_sets_optional(); + + return result; +} + +HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { + assert_heap_not_locked_and_not_at_safepoint(); + assert(!is_humongous(word_size), "we do not allow humongous TLABs"); + + uint dummy_gc_count_before; + uint dummy_gclocker_retry_count = 0; + return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count); +} + +HeapWord* +G1CollectedHeap::mem_allocate(size_t word_size, + bool* gc_overhead_limit_was_exceeded) { + assert_heap_not_locked_and_not_at_safepoint(); + + // Loop until the allocation is satisfied, or unsatisfied after GC. + for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { + uint gc_count_before; + + HeapWord* result = NULL; + if (!is_humongous(word_size)) { + result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count); + } else { + result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count); + } + if (result != NULL) { + return result; + } + + // Create the garbage collection operation... + VM_G1CollectForAllocation op(gc_count_before, word_size); + op.set_allocation_context(AllocationContext::current()); + + // ...and get the VM thread to execute it. + VMThread::execute(&op); + + if (op.prologue_succeeded() && op.pause_succeeded()) { + // If the operation was successful we'll return the result even + // if it is NULL. If the allocation attempt failed immediately + // after a Full GC, it's unlikely we'll be able to allocate now. + HeapWord* result = op.result(); + if (result != NULL && !is_humongous(word_size)) { + // Allocations that take place on VM operations do not do any + // card dirtying and we have to do it here. We only have to do + // this for non-humongous allocations, though. + dirty_young_block(result, word_size); + } + return result; + } else { + if (gclocker_retry_count > GCLockerRetryAllocationCount) { + return NULL; + } + assert(op.result() == NULL, + "the result should be NULL if the VM op did not succeed"); + } + + // Give a warning if we seem to be looping forever. + if ((QueuedAllocationWarningCount > 0) && + (try_count % QueuedAllocationWarningCount == 0)) { + warning("G1CollectedHeap::mem_allocate retries %d times", try_count); + } + } + + ShouldNotReachHere(); + return NULL; +} + +HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size, + AllocationContext_t context, + uint* gc_count_before_ret, + uint* gclocker_retry_count_ret) { + // Make sure you read the note in attempt_allocation_humongous(). + + assert_heap_not_locked_and_not_at_safepoint(); + assert(!is_humongous(word_size), "attempt_allocation_slow() should not " + "be called for humongous allocation requests"); + + // We should only get here after the first-level allocation attempt + // (attempt_allocation()) failed to allocate. + + // We will loop until a) we manage to successfully perform the + // allocation or b) we successfully schedule a collection which + // fails to perform the allocation. b) is the only case when we'll + // return NULL. + HeapWord* result = NULL; + for (int try_count = 1; /* we'll return */; try_count += 1) { + bool should_try_gc; + uint gc_count_before; + + { + MutexLockerEx x(Heap_lock); + result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, + false /* bot_updates */); + if (result != NULL) { + return result; + } + + // If we reach here, attempt_allocation_locked() above failed to + // allocate a new region. So the mutator alloc region should be NULL. + assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here"); + + if (GC_locker::is_active_and_needs_gc()) { + if (g1_policy()->can_expand_young_list()) { + // No need for an ergo verbose message here, + // can_expand_young_list() does this when it returns true. + result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size, + false /* bot_updates */); + if (result != NULL) { + return result; + } + } + should_try_gc = false; + } else { + // The GCLocker may not be active but the GCLocker initiated + // GC may not yet have been performed (GCLocker::needs_gc() + // returns true). In this case we do not try this GC and + // wait until the GCLocker initiated GC is performed, and + // then retry the allocation. + if (GC_locker::needs_gc()) { + should_try_gc = false; + } else { + // Read the GC count while still holding the Heap_lock. + gc_count_before = total_collections(); + should_try_gc = true; + } + } + } + + if (should_try_gc) { + bool succeeded; + result = do_collection_pause(word_size, gc_count_before, &succeeded, + GCCause::_g1_inc_collection_pause); + if (result != NULL) { + assert(succeeded, "only way to get back a non-NULL result"); + return result; + } + + if (succeeded) { + // If we get here we successfully scheduled a collection which + // failed to allocate. No point in trying to allocate + // further. We'll just return NULL. + MutexLockerEx x(Heap_lock); + *gc_count_before_ret = total_collections(); + return NULL; + } + } else { + if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { + MutexLockerEx x(Heap_lock); + *gc_count_before_ret = total_collections(); + return NULL; + } + // The GCLocker is either active or the GCLocker initiated + // GC has not yet been performed. Stall until it is and + // then retry the allocation. + GC_locker::stall_until_clear(); + (*gclocker_retry_count_ret) += 1; + } + + // We can reach here if we were unsuccessful in scheduling a + // collection (because another thread beat us to it) or if we were + // stalled due to the GC locker. In either can we should retry the + // allocation attempt in case another thread successfully + // performed a collection and reclaimed enough space. We do the + // first attempt (without holding the Heap_lock) here and the + // follow-on attempt will be at the start of the next loop + // iteration (after taking the Heap_lock). + result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size, + false /* bot_updates */); + if (result != NULL) { + return result; + } + + // Give a warning if we seem to be looping forever. + if ((QueuedAllocationWarningCount > 0) && + (try_count % QueuedAllocationWarningCount == 0)) { + warning("G1CollectedHeap::attempt_allocation_slow() " + "retries %d times", try_count); + } + } + + ShouldNotReachHere(); + return NULL; +} + +HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size, + uint* gc_count_before_ret, + uint* gclocker_retry_count_ret) { + // The structure of this method has a lot of similarities to + // attempt_allocation_slow(). The reason these two were not merged + // into a single one is that such a method would require several "if + // allocation is not humongous do this, otherwise do that" + // conditional paths which would obscure its flow. In fact, an early + // version of this code did use a unified method which was harder to + // follow and, as a result, it had subtle bugs that were hard to + // track down. So keeping these two methods separate allows each to + // be more readable. It will be good to keep these two in sync as + // much as possible. + + assert_heap_not_locked_and_not_at_safepoint(); + assert(is_humongous(word_size), "attempt_allocation_humongous() " + "should only be called for humongous allocations"); + + // Humongous objects can exhaust the heap quickly, so we should check if we + // need to start a marking cycle at each humongous object allocation. We do + // the check before we do the actual allocation. The reason for doing it + // before the allocation is that we avoid having to keep track of the newly + // allocated memory while we do a GC. + if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", + word_size)) { + collect(GCCause::_g1_humongous_allocation); + } + + // We will loop until a) we manage to successfully perform the + // allocation or b) we successfully schedule a collection which + // fails to perform the allocation. b) is the only case when we'll + // return NULL. + HeapWord* result = NULL; + for (int try_count = 1; /* we'll return */; try_count += 1) { + bool should_try_gc; + uint gc_count_before; + + { + MutexLockerEx x(Heap_lock); + + // Given that humongous objects are not allocated in young + // regions, we'll first try to do the allocation without doing a + // collection hoping that there's enough space in the heap. + result = humongous_obj_allocate(word_size, AllocationContext::current()); + if (result != NULL) { + return result; + } + + if (GC_locker::is_active_and_needs_gc()) { + should_try_gc = false; + } else { + // The GCLocker may not be active but the GCLocker initiated + // GC may not yet have been performed (GCLocker::needs_gc() + // returns true). In this case we do not try this GC and + // wait until the GCLocker initiated GC is performed, and + // then retry the allocation. + if (GC_locker::needs_gc()) { + should_try_gc = false; + } else { + // Read the GC count while still holding the Heap_lock. + gc_count_before = total_collections(); + should_try_gc = true; + } + } + } + + if (should_try_gc) { + // If we failed to allocate the humongous object, we should try to + // do a collection pause (if we're allowed) in case it reclaims + // enough space for the allocation to succeed after the pause. + + bool succeeded; + result = do_collection_pause(word_size, gc_count_before, &succeeded, + GCCause::_g1_humongous_allocation); + if (result != NULL) { + assert(succeeded, "only way to get back a non-NULL result"); + return result; + } + + if (succeeded) { + // If we get here we successfully scheduled a collection which + // failed to allocate. No point in trying to allocate + // further. We'll just return NULL. + MutexLockerEx x(Heap_lock); + *gc_count_before_ret = total_collections(); + return NULL; + } + } else { + if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) { + MutexLockerEx x(Heap_lock); + *gc_count_before_ret = total_collections(); + return NULL; + } + // The GCLocker is either active or the GCLocker initiated + // GC has not yet been performed. Stall until it is and + // then retry the allocation. + GC_locker::stall_until_clear(); + (*gclocker_retry_count_ret) += 1; + } + + // We can reach here if we were unsuccessful in scheduling a + // collection (because another thread beat us to it) or if we were + // stalled due to the GC locker. In either can we should retry the + // allocation attempt in case another thread successfully + // performed a collection and reclaimed enough space. Give a + // warning if we seem to be looping forever. + + if ((QueuedAllocationWarningCount > 0) && + (try_count % QueuedAllocationWarningCount == 0)) { + warning("G1CollectedHeap::attempt_allocation_humongous() " + "retries %d times", try_count); + } + } + + ShouldNotReachHere(); + return NULL; +} + +HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, + AllocationContext_t context, + bool expect_null_mutator_alloc_region) { + assert_at_safepoint(true /* should_be_vm_thread */); + assert(_allocator->mutator_alloc_region(context)->get() == NULL || + !expect_null_mutator_alloc_region, + "the current alloc region was unexpectedly found to be non-NULL"); + + if (!is_humongous(word_size)) { + return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size, + false /* bot_updates */); + } else { + HeapWord* result = humongous_obj_allocate(word_size, context); + if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { + g1_policy()->set_initiate_conc_mark_if_possible(); + } + return result; + } + + ShouldNotReachHere(); +} + +class PostMCRemSetClearClosure: public HeapRegionClosure { + G1CollectedHeap* _g1h; + ModRefBarrierSet* _mr_bs; +public: + PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) : + _g1h(g1h), _mr_bs(mr_bs) {} + + bool doHeapRegion(HeapRegion* r) { + HeapRegionRemSet* hrrs = r->rem_set(); + + if (r->is_continues_humongous()) { + // We'll assert that the strong code root list and RSet is empty + assert(hrrs->strong_code_roots_list_length() == 0, "sanity"); + assert(hrrs->occupied() == 0, "RSet should be empty"); + return false; + } + + _g1h->reset_gc_time_stamps(r); + hrrs->clear(); + // You might think here that we could clear just the cards + // corresponding to the used region. But no: if we leave a dirty card + // in a region we might allocate into, then it would prevent that card + // from being enqueued, and cause it to be missed. + // Re: the performance cost: we shouldn't be doing full GC anyway! + _mr_bs->clear(MemRegion(r->bottom(), r->end())); + + return false; + } +}; + +void G1CollectedHeap::clear_rsets_post_compaction() { + PostMCRemSetClearClosure rs_clear(this, g1_barrier_set()); + heap_region_iterate(&rs_clear); +} + +class RebuildRSOutOfRegionClosure: public HeapRegionClosure { + G1CollectedHeap* _g1h; + UpdateRSOopClosure _cl; +public: + RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) : + _cl(g1->g1_rem_set(), worker_i), + _g1h(g1) + { } + + bool doHeapRegion(HeapRegion* r) { + if (!r->is_continues_humongous()) { + _cl.set_from(r); + r->oop_iterate(&_cl); + } + return false; + } +}; + +class ParRebuildRSTask: public AbstractGangTask { + G1CollectedHeap* _g1; + HeapRegionClaimer _hrclaimer; + +public: + ParRebuildRSTask(G1CollectedHeap* g1) : + AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {} + + void work(uint worker_id) { + RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id); + _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer); + } +}; + +class PostCompactionPrinterClosure: public HeapRegionClosure { +private: + G1HRPrinter* _hr_printer; +public: + bool doHeapRegion(HeapRegion* hr) { + assert(!hr->is_young(), "not expecting to find young regions"); + if (hr->is_free()) { + // We only generate output for non-empty regions. + } else if (hr->is_starts_humongous()) { + if (hr->region_num() == 1) { + // single humongous region + _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous); + } else { + _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous); + } + } else if (hr->is_continues_humongous()) { + _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous); + } else if (hr->is_old()) { + _hr_printer->post_compaction(hr, G1HRPrinter::Old); + } else { + ShouldNotReachHere(); + } + return false; + } + + PostCompactionPrinterClosure(G1HRPrinter* hr_printer) + : _hr_printer(hr_printer) { } +}; + +void G1CollectedHeap::print_hrm_post_compaction() { + PostCompactionPrinterClosure cl(hr_printer()); + heap_region_iterate(&cl); +} + +bool G1CollectedHeap::do_collection(bool explicit_gc, + bool clear_all_soft_refs, + size_t word_size) { + assert_at_safepoint(true /* should_be_vm_thread */); + + if (GC_locker::check_active_before_gc()) { + return false; + } + + STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); + gc_timer->register_gc_start(); + + SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); + gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); + + SvcGCMarker sgcm(SvcGCMarker::FULL); + ResourceMark rm; + + G1Log::update_level(); + print_heap_before_gc(); + trace_heap_before_gc(gc_tracer); + + size_t metadata_prev_used = MetaspaceAux::used_bytes(); + + verify_region_sets_optional(); + + const bool do_clear_all_soft_refs = clear_all_soft_refs || + collector_policy()->should_clear_all_soft_refs(); + + ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); + + { + IsGCActiveMark x; + + // Timing + assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant"); + TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); + + { + GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id()); + TraceCollectorStats tcs(g1mm()->full_collection_counters()); + TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); + + g1_policy()->record_full_collection_start(); + + // Note: When we have a more flexible GC logging framework that + // allows us to add optional attributes to a GC log record we + // could consider timing and reporting how long we wait in the + // following two methods. + wait_while_free_regions_coming(); + // If we start the compaction before the CM threads finish + // scanning the root regions we might trip them over as we'll + // be moving objects / updating references. So let's wait until + // they are done. By telling them to abort, they should complete + // early. + _cm->root_regions()->abort(); + _cm->root_regions()->wait_until_scan_finished(); + append_secondary_free_list_if_not_empty_with_lock(); + + gc_prologue(true); + increment_total_collections(true /* full gc */); + increment_old_marking_cycles_started(); + + assert(used() == recalculate_used(), "Should be equal"); + + verify_before_gc(); + + check_bitmaps("Full GC Start"); + pre_full_gc_dump(gc_timer); + + COMPILER2_PRESENT(DerivedPointerTable::clear()); + + // Disable discovery and empty the discovered lists + // for the CM ref processor. + ref_processor_cm()->disable_discovery(); + ref_processor_cm()->abandon_partial_discovery(); + ref_processor_cm()->verify_no_references_recorded(); + + // Abandon current iterations of concurrent marking and concurrent + // refinement, if any are in progress. We have to do this before + // wait_until_scan_finished() below. + concurrent_mark()->abort(); + + // Make sure we'll choose a new allocation region afterwards. + _allocator->release_mutator_alloc_region(); + _allocator->abandon_gc_alloc_regions(); + g1_rem_set()->cleanupHRRS(); + + // We should call this after we retire any currently active alloc + // regions so that all the ALLOC / RETIRE events are generated + // before the start GC event. + _hr_printer.start_gc(true /* full */, (size_t) total_collections()); + + // We may have added regions to the current incremental collection + // set between the last GC or pause and now. We need to clear the + // incremental collection set and then start rebuilding it afresh + // after this full GC. + abandon_collection_set(g1_policy()->inc_cset_head()); + g1_policy()->clear_incremental_cset(); + g1_policy()->stop_incremental_cset_building(); + + tear_down_region_sets(false /* free_list_only */); + g1_policy()->set_gcs_are_young(true); + + // See the comments in g1CollectedHeap.hpp and + // G1CollectedHeap::ref_processing_init() about + // how reference processing currently works in G1. + + // Temporarily make discovery by the STW ref processor single threaded (non-MT). + ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false); + + // Temporarily clear the STW ref processor's _is_alive_non_header field. + ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL); + + ref_processor_stw()->enable_discovery(); + ref_processor_stw()->setup_policy(do_clear_all_soft_refs); + + // Do collection work + { + HandleMark hm; // Discard invalid handles created during gc + G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs); + } + + assert(num_free_regions() == 0, "we should not have added any free regions"); + rebuild_region_sets(false /* free_list_only */); + + // Enqueue any discovered reference objects that have + // not been removed from the discovered lists. + ref_processor_stw()->enqueue_discovered_references(); + + COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); + + MemoryService::track_memory_usage(); + + assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); + ref_processor_stw()->verify_no_references_recorded(); + + // Delete metaspaces for unloaded class loaders and clean up loader_data graph + ClassLoaderDataGraph::purge(); + MetaspaceAux::verify_metrics(); + + // Note: since we've just done a full GC, concurrent + // marking is no longer active. Therefore we need not + // re-enable reference discovery for the CM ref processor. + // That will be done at the start of the next marking cycle. + assert(!ref_processor_cm()->discovery_enabled(), "Postcondition"); + ref_processor_cm()->verify_no_references_recorded(); + + reset_gc_time_stamp(); + // Since everything potentially moved, we will clear all remembered + // sets, and clear all cards. Later we will rebuild remembered + // sets. We will also reset the GC time stamps of the regions. + clear_rsets_post_compaction(); + check_gc_time_stamps(); + + // Resize the heap if necessary. + resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size); + + if (_hr_printer.is_active()) { + // We should do this after we potentially resize the heap so + // that all the COMMIT / UNCOMMIT events are generated before + // the end GC event. + + print_hrm_post_compaction(); + _hr_printer.end_gc(true /* full */, (size_t) total_collections()); + } + + G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); + if (hot_card_cache->use_cache()) { + hot_card_cache->reset_card_counts(); + hot_card_cache->reset_hot_cache(); + } + + // Rebuild remembered sets of all regions. + uint n_workers = + AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), + workers()->active_workers(), + Threads::number_of_non_daemon_threads()); + assert(UseDynamicNumberOfGCThreads || + n_workers == workers()->total_workers(), + "If not dynamic should be using all the workers"); + workers()->set_active_workers(n_workers); + // Set parallel threads in the heap (_n_par_threads) only + // before a parallel phase and always reset it to 0 after + // the phase so that the number of parallel threads does + // no get carried forward to a serial phase where there + // may be code that is "possibly_parallel". + set_par_threads(n_workers); + + ParRebuildRSTask rebuild_rs_task(this); + assert(UseDynamicNumberOfGCThreads || + workers()->active_workers() == workers()->total_workers(), + "Unless dynamic should use total workers"); + // Use the most recent number of active workers + assert(workers()->active_workers() > 0, + "Active workers not properly set"); + set_par_threads(workers()->active_workers()); + workers()->run_task(&rebuild_rs_task); + set_par_threads(0); + + // Rebuild the strong code root lists for each region + rebuild_strong_code_roots(); + + if (true) { // FIXME + MetaspaceGC::compute_new_size(); + } + +#ifdef TRACESPINNING + ParallelTaskTerminator::print_termination_counts(); +#endif + + // Discard all rset updates + JavaThread::dirty_card_queue_set().abandon_logs(); + assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); + + _young_list->reset_sampled_info(); + // At this point there should be no regions in the + // entire heap tagged as young. + assert(check_young_list_empty(true /* check_heap */), + "young list should be empty at this point"); + + // Update the number of full collections that have been completed. + increment_old_marking_cycles_completed(false /* concurrent */); + + _hrm.verify_optional(); + verify_region_sets_optional(); + + verify_after_gc(); + + // Clear the previous marking bitmap, if needed for bitmap verification. + // Note we cannot do this when we clear the next marking bitmap in + // ConcurrentMark::abort() above since VerifyDuringGC verifies the + // objects marked during a full GC against the previous bitmap. + // But we need to clear it before calling check_bitmaps below since + // the full GC has compacted objects and updated TAMS but not updated + // the prev bitmap. + if (G1VerifyBitmaps) { + ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll(); + } + check_bitmaps("Full GC End"); + + // Start a new incremental collection set for the next pause + assert(g1_policy()->collection_set() == NULL, "must be"); + g1_policy()->start_incremental_cset_building(); + + clear_cset_fast_test(); + + _allocator->init_mutator_alloc_region(); + + g1_policy()->record_full_collection_end(); + + if (G1Log::fine()) { + g1_policy()->print_heap_transition(); + } + + // We must call G1MonitoringSupport::update_sizes() in the same scoping level + // as an active TraceMemoryManagerStats object (i.e. before the destructor for the + // TraceMemoryManagerStats is called) so that the G1 memory pools are updated + // before any GC notifications are raised. + g1mm()->update_sizes(); + + gc_epilogue(true); + } + + if (G1Log::finer()) { + g1_policy()->print_detailed_heap_transition(true /* full */); + } + + print_heap_after_gc(); + trace_heap_after_gc(gc_tracer); + + post_full_gc_dump(gc_timer); + + gc_timer->register_gc_end(); + gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); + } + + return true; +} + +void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { + // do_collection() will return whether it succeeded in performing + // the GC. Currently, there is no facility on the + // do_full_collection() API to notify the caller than the collection + // did not succeed (e.g., because it was locked out by the GC + // locker). So, right now, we'll ignore the return value. + bool dummy = do_collection(true, /* explicit_gc */ + clear_all_soft_refs, + 0 /* word_size */); +} + +// This code is mostly copied from TenuredGeneration. +void +G1CollectedHeap:: +resize_if_necessary_after_full_collection(size_t word_size) { + // Include the current allocation, if any, and bytes that will be + // pre-allocated to support collections, as "used". + const size_t used_after_gc = used(); + const size_t capacity_after_gc = capacity(); + const size_t free_after_gc = capacity_after_gc - used_after_gc; + + // This is enforced in arguments.cpp. + assert(MinHeapFreeRatio <= MaxHeapFreeRatio, + "otherwise the code below doesn't make sense"); + + // We don't have floating point command-line arguments + const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; + const double maximum_used_percentage = 1.0 - minimum_free_percentage; + const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; + const double minimum_used_percentage = 1.0 - maximum_free_percentage; + + const size_t min_heap_size = collector_policy()->min_heap_byte_size(); + const size_t max_heap_size = collector_policy()->max_heap_byte_size(); + + // We have to be careful here as these two calculations can overflow + // 32-bit size_t's. + double used_after_gc_d = (double) used_after_gc; + double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; + double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; + + // Let's make sure that they are both under the max heap size, which + // by default will make them fit into a size_t. + double desired_capacity_upper_bound = (double) max_heap_size; + minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, + desired_capacity_upper_bound); + maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, + desired_capacity_upper_bound); + + // We can now safely turn them into size_t's. + size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; + size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; + + // This assert only makes sense here, before we adjust them + // with respect to the min and max heap size. + assert(minimum_desired_capacity <= maximum_desired_capacity, + err_msg("minimum_desired_capacity = "SIZE_FORMAT", " + "maximum_desired_capacity = "SIZE_FORMAT, + minimum_desired_capacity, maximum_desired_capacity)); + + // Should not be greater than the heap max size. No need to adjust + // it with respect to the heap min size as it's a lower bound (i.e., + // we'll try to make the capacity larger than it, not smaller). + minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); + // Should not be less than the heap min size. No need to adjust it + // with respect to the heap max size as it's an upper bound (i.e., + // we'll try to make the capacity smaller than it, not greater). + maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); + + if (capacity_after_gc < minimum_desired_capacity) { + // Don't expand unless it's significant + size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; + ergo_verbose4(ErgoHeapSizing, + "attempt heap expansion", + ergo_format_reason("capacity lower than " + "min desired capacity after Full GC") + ergo_format_byte("capacity") + ergo_format_byte("occupancy") + ergo_format_byte_perc("min desired capacity"), + capacity_after_gc, used_after_gc, + minimum_desired_capacity, (double) MinHeapFreeRatio); + expand(expand_bytes); + + // No expansion, now see if we want to shrink + } else if (capacity_after_gc > maximum_desired_capacity) { + // Capacity too large, compute shrinking size + size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; + ergo_verbose4(ErgoHeapSizing, + "attempt heap shrinking", + ergo_format_reason("capacity higher than " + "max desired capacity after Full GC") + ergo_format_byte("capacity") + ergo_format_byte("occupancy") + ergo_format_byte_perc("max desired capacity"), + capacity_after_gc, used_after_gc, + maximum_desired_capacity, (double) MaxHeapFreeRatio); + shrink(shrink_bytes); + } +} + + +HeapWord* +G1CollectedHeap::satisfy_failed_allocation(size_t word_size, + AllocationContext_t context, + bool* succeeded) { + assert_at_safepoint(true /* should_be_vm_thread */); + + *succeeded = true; + // Let's attempt the allocation first. + HeapWord* result = + attempt_allocation_at_safepoint(word_size, + context, + false /* expect_null_mutator_alloc_region */); + if (result != NULL) { + assert(*succeeded, "sanity"); + return result; + } + + // In a G1 heap, we're supposed to keep allocation from failing by + // incremental pauses. Therefore, at least for now, we'll favor + // expansion over collection. (This might change in the future if we can + // do something smarter than full collection to satisfy a failed alloc.) + result = expand_and_allocate(word_size, context); + if (result != NULL) { + assert(*succeeded, "sanity"); + return result; + } + + // Expansion didn't work, we'll try to do a Full GC. + bool gc_succeeded = do_collection(false, /* explicit_gc */ + false, /* clear_all_soft_refs */ + word_size); + if (!gc_succeeded) { + *succeeded = false; + return NULL; + } + + // Retry the allocation + result = attempt_allocation_at_safepoint(word_size, + context, + true /* expect_null_mutator_alloc_region */); + if (result != NULL) { + assert(*succeeded, "sanity"); + return result; + } + + // Then, try a Full GC that will collect all soft references. + gc_succeeded = do_collection(false, /* explicit_gc */ + true, /* clear_all_soft_refs */ + word_size); + if (!gc_succeeded) { + *succeeded = false; + return NULL; + } + + // Retry the allocation once more + result = attempt_allocation_at_safepoint(word_size, + context, + true /* expect_null_mutator_alloc_region */); + if (result != NULL) { + assert(*succeeded, "sanity"); + return result; + } + + assert(!collector_policy()->should_clear_all_soft_refs(), + "Flag should have been handled and cleared prior to this point"); + + // What else? We might try synchronous finalization later. If the total + // space available is large enough for the allocation, then a more + // complete compaction phase than we've tried so far might be + // appropriate. + assert(*succeeded, "sanity"); + return NULL; +} + +// Attempting to expand the heap sufficiently +// to support an allocation of the given "word_size". If +// successful, perform the allocation and return the address of the +// allocated block, or else "NULL". + +HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) { + assert_at_safepoint(true /* should_be_vm_thread */); + + verify_region_sets_optional(); + + size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); + ergo_verbose1(ErgoHeapSizing, + "attempt heap expansion", + ergo_format_reason("allocation request failed") + ergo_format_byte("allocation request"), + word_size * HeapWordSize); + if (expand(expand_bytes)) { + _hrm.verify_optional(); + verify_region_sets_optional(); + return attempt_allocation_at_safepoint(word_size, + context, + false /* expect_null_mutator_alloc_region */); + } + return NULL; +} + +bool G1CollectedHeap::expand(size_t expand_bytes) { + size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); + aligned_expand_bytes = align_size_up(aligned_expand_bytes, + HeapRegion::GrainBytes); + ergo_verbose2(ErgoHeapSizing, + "expand the heap", + ergo_format_byte("requested expansion amount") + ergo_format_byte("attempted expansion amount"), + expand_bytes, aligned_expand_bytes); + + if (is_maximal_no_gc()) { + ergo_verbose0(ErgoHeapSizing, + "did not expand the heap", + ergo_format_reason("heap already fully expanded")); + return false; + } + + uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); + assert(regions_to_expand > 0, "Must expand by at least one region"); + + uint expanded_by = _hrm.expand_by(regions_to_expand); + + if (expanded_by > 0) { + size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; + assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); + g1_policy()->record_new_heap_size(num_regions()); + } else { + ergo_verbose0(ErgoHeapSizing, + "did not expand the heap", + ergo_format_reason("heap expansion operation failed")); + // The expansion of the virtual storage space was unsuccessful. + // Let's see if it was because we ran out of swap. + if (G1ExitOnExpansionFailure && + _hrm.available() >= regions_to_expand) { + // We had head room... + vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); + } + } + return regions_to_expand > 0; +} + +void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { + size_t aligned_shrink_bytes = + ReservedSpace::page_align_size_down(shrink_bytes); + aligned_shrink_bytes = align_size_down(aligned_shrink_bytes, + HeapRegion::GrainBytes); + uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); + + uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); + size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; + + ergo_verbose3(ErgoHeapSizing, + "shrink the heap", + ergo_format_byte("requested shrinking amount") + ergo_format_byte("aligned shrinking amount") + ergo_format_byte("attempted shrinking amount"), + shrink_bytes, aligned_shrink_bytes, shrunk_bytes); + if (num_regions_removed > 0) { + g1_policy()->record_new_heap_size(num_regions()); + } else { + ergo_verbose0(ErgoHeapSizing, + "did not shrink the heap", + ergo_format_reason("heap shrinking operation failed")); + } +} + +void G1CollectedHeap::shrink(size_t shrink_bytes) { + verify_region_sets_optional(); + + // We should only reach here at the end of a Full GC which means we + // should not not be holding to any GC alloc regions. The method + // below will make sure of that and do any remaining clean up. + _allocator->abandon_gc_alloc_regions(); + + // Instead of tearing down / rebuilding the free lists here, we + // could instead use the remove_all_pending() method on free_list to + // remove only the ones that we need to remove. + tear_down_region_sets(true /* free_list_only */); + shrink_helper(shrink_bytes); + rebuild_region_sets(true /* free_list_only */); + + _hrm.verify_optional(); + verify_region_sets_optional(); +} + +// Public methods. + +#ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away +#pragma warning( disable:4355 ) // 'this' : used in base member initializer list +#endif // _MSC_VER + + +G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : + CollectedHeap(), + _g1_policy(policy_), + _dirty_card_queue_set(false), + _into_cset_dirty_card_queue_set(false), + _is_alive_closure_cm(this), + _is_alive_closure_stw(this), + _ref_processor_cm(NULL), + _ref_processor_stw(NULL), + _bot_shared(NULL), + _evac_failure_scan_stack(NULL), + _mark_in_progress(false), + _cg1r(NULL), + _g1mm(NULL), + _refine_cte_cl(NULL), + _full_collection(false), + _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()), + _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), + _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), + _humongous_reclaim_candidates(), + _has_humongous_reclaim_candidates(false), + _free_regions_coming(false), + _young_list(new YoungList(this)), + _gc_time_stamp(0), + _survivor_plab_stats(YoungPLABSize, PLABWeight), + _old_plab_stats(OldPLABSize, PLABWeight), + _expand_heap_after_alloc_failure(true), + _surviving_young_words(NULL), + _old_marking_cycles_started(0), + _old_marking_cycles_completed(0), + _concurrent_cycle_started(false), + _heap_summary_sent(false), + _in_cset_fast_test(), + _dirty_cards_region_list(NULL), + _worker_cset_start_region(NULL), + _worker_cset_start_region_time_stamp(NULL), + _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), + _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()), + _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), + _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) { + + _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, + /* are_GC_task_threads */true, + /* are_ConcurrentGC_threads */false); + _workers->initialize_workers(); + + _allocator = G1Allocator::create_allocator(this); + _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2; + + int n_queues = MAX2((int)ParallelGCThreads, 1); + _task_queues = new RefToScanQueueSet(n_queues); + + uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets(); + assert(n_rem_sets > 0, "Invariant."); + + _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC); + _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC); + _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); + + for (int i = 0; i < n_queues; i++) { + RefToScanQueue* q = new RefToScanQueue(); + q->initialize(); + _task_queues->register_queue(i, q); + ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); + } + clear_cset_start_regions(); + + // Initialize the G1EvacuationFailureALot counters and flags. + NOT_PRODUCT(reset_evacuation_should_fail();) + + guarantee(_task_queues != NULL, "task_queues allocation failure."); +} + +G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, + size_t size, + size_t translation_factor) { + size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); + // Allocate a new reserved space, preferring to use large pages. + ReservedSpace rs(size, preferred_page_size); + G1RegionToSpaceMapper* result = + G1RegionToSpaceMapper::create_mapper(rs, + size, + rs.alignment(), + HeapRegion::GrainBytes, + translation_factor, + mtGC); + if (TracePageSizes) { + gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT, + description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size); + } + return result; +} + +jint G1CollectedHeap::initialize() { + CollectedHeap::pre_initialize(); + os::enable_vtime(); + + G1Log::init(); + + // Necessary to satisfy locking discipline assertions. + + MutexLocker x(Heap_lock); + + // We have to initialize the printer before committing the heap, as + // it will be used then. + _hr_printer.set_active(G1PrintHeapRegions); + + // While there are no constraints in the GC code that HeapWordSize + // be any particular value, there are multiple other areas in the + // system which believe this to be true (e.g. oop->object_size in some + // cases incorrectly returns the size in wordSize units rather than + // HeapWordSize). + guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); + + size_t init_byte_size = collector_policy()->initial_heap_byte_size(); + size_t max_byte_size = collector_policy()->max_heap_byte_size(); + size_t heap_alignment = collector_policy()->heap_alignment(); + + // Ensure that the sizes are properly aligned. + Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); + Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); + Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); + + _refine_cte_cl = new RefineCardTableEntryClosure(); + + _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl); + + // Reserve the maximum. + + // When compressed oops are enabled, the preferred heap base + // is calculated by subtracting the requested size from the + // 32Gb boundary and using the result as the base address for + // heap reservation. If the requested size is not aligned to + // HeapRegion::GrainBytes (i.e. the alignment that is passed + // into the ReservedHeapSpace constructor) then the actual + // base of the reserved heap may end up differing from the + // address that was requested (i.e. the preferred heap base). + // If this happens then we could end up using a non-optimal + // compressed oops mode. + + ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, + heap_alignment); + + initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); + + // Create the barrier set for the entire reserved region. + G1SATBCardTableLoggingModRefBS* bs + = new G1SATBCardTableLoggingModRefBS(reserved_region()); + bs->initialize(); + assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity"); + set_barrier_set(bs); + + // Also create a G1 rem set. + _g1_rem_set = new G1RemSet(this, g1_barrier_set()); + + // Carve out the G1 part of the heap. + + ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); + size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); + G1RegionToSpaceMapper* heap_storage = + G1RegionToSpaceMapper::create_mapper(g1_rs, + g1_rs.size(), + page_size, + HeapRegion::GrainBytes, + 1, + mtJavaHeap); + os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(), + max_byte_size, page_size, + heap_rs.base(), + heap_rs.size()); + heap_storage->set_mapping_changed_listener(&_listener); + + // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. + G1RegionToSpaceMapper* bot_storage = + create_aux_memory_mapper("Block offset table", + G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize), + G1BlockOffsetSharedArray::heap_map_factor()); + + ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize)); + G1RegionToSpaceMapper* cardtable_storage = + create_aux_memory_mapper("Card table", + G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize), + G1SATBCardTableLoggingModRefBS::heap_map_factor()); + + G1RegionToSpaceMapper* card_counts_storage = + create_aux_memory_mapper("Card counts table", + G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), + G1CardCounts::heap_map_factor()); + + size_t bitmap_size = CMBitMap::compute_size(g1_rs.size()); + G1RegionToSpaceMapper* prev_bitmap_storage = + create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor()); + G1RegionToSpaceMapper* next_bitmap_storage = + create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor()); + + _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); + g1_barrier_set()->initialize(cardtable_storage); + // Do later initialization work for concurrent refinement. + _cg1r->init(card_counts_storage); + + // 6843694 - ensure that the maximum region index can fit + // in the remembered set structures. + const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; + guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); + + size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; + guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); + guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, + "too many cards per region"); + + FreeRegionList::set_unrealistically_long_length(max_regions() + 1); + + _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage); + + { + HeapWord* start = _hrm.reserved().start(); + HeapWord* end = _hrm.reserved().end(); + size_t granularity = HeapRegion::GrainBytes; + + _in_cset_fast_test.initialize(start, end, granularity); + _humongous_reclaim_candidates.initialize(start, end, granularity); + } + + // Create the ConcurrentMark data structure and thread. + // (Must do this late, so that "max_regions" is defined.) + _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); + if (_cm == NULL || !_cm->completed_initialization()) { + vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark"); + return JNI_ENOMEM; + } + _cmThread = _cm->cmThread(); + + // Initialize the from_card cache structure of HeapRegionRemSet. + HeapRegionRemSet::init_heap(max_regions()); + + // Now expand into the initial heap size. + if (!expand(init_byte_size)) { + vm_shutdown_during_initialization("Failed to allocate initial heap."); + return JNI_ENOMEM; + } + + // Perform any initialization actions delegated to the policy. + g1_policy()->init(); + + JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, + SATB_Q_FL_lock, + G1SATBProcessCompletedThreshold, + Shared_SATB_Q_lock); + + JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl, + DirtyCardQ_CBL_mon, + DirtyCardQ_FL_lock, + concurrent_g1_refine()->yellow_zone(), + concurrent_g1_refine()->red_zone(), + Shared_DirtyCardQ_lock); + + dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code + DirtyCardQ_CBL_mon, + DirtyCardQ_FL_lock, + -1, // never trigger processing + -1, // no limit on length + Shared_DirtyCardQ_lock, + &JavaThread::dirty_card_queue_set()); + + // Initialize the card queue set used to hold cards containing + // references into the collection set. + _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code + DirtyCardQ_CBL_mon, + DirtyCardQ_FL_lock, + -1, // never trigger processing + -1, // no limit on length + Shared_DirtyCardQ_lock, + &JavaThread::dirty_card_queue_set()); + + // Here we allocate the dummy HeapRegion that is required by the + // G1AllocRegion class. + HeapRegion* dummy_region = _hrm.get_dummy_region(); + + // We'll re-use the same region whether the alloc region will + // require BOT updates or not and, if it doesn't, then a non-young + // region will complain that it cannot support allocations without + // BOT updates. So we'll tag the dummy region as eden to avoid that. + dummy_region->set_eden(); + // Make sure it's full. + dummy_region->set_top(dummy_region->end()); + G1AllocRegion::setup(this, dummy_region); + + _allocator->init_mutator_alloc_region(); + + // Do create of the monitoring and management support so that + // values in the heap have been properly initialized. + _g1mm = new G1MonitoringSupport(this); + + G1StringDedup::initialize(); + + return JNI_OK; +} + +void G1CollectedHeap::stop() { + // Stop all concurrent threads. We do this to make sure these threads + // do not continue to execute and access resources (e.g. gclog_or_tty) + // that are destroyed during shutdown. + _cg1r->stop(); + _cmThread->stop(); + if (G1StringDedup::is_enabled()) { + G1StringDedup::stop(); + } +} + +size_t G1CollectedHeap::conservative_max_heap_alignment() { + return HeapRegion::max_region_size(); +} + +void G1CollectedHeap::post_initialize() { + CollectedHeap::post_initialize(); + ref_processing_init(); +} + +void G1CollectedHeap::ref_processing_init() { + // Reference processing in G1 currently works as follows: + // + // * There are two reference processor instances. One is + // used to record and process discovered references + // during concurrent marking; the other is used to + // record and process references during STW pauses + // (both full and incremental). + // * Both ref processors need to 'span' the entire heap as + // the regions in the collection set may be dotted around. + // + // * For the concurrent marking ref processor: + // * Reference discovery is enabled at initial marking. + // * Reference discovery is disabled and the discovered + // references processed etc during remarking. + // * Reference discovery is MT (see below). + // * Reference discovery requires a barrier (see below). + // * Reference processing may or may not be MT + // (depending on the value of ParallelRefProcEnabled + // and ParallelGCThreads). + // * A full GC disables reference discovery by the CM + // ref processor and abandons any entries on it's + // discovered lists. + // + // * For the STW processor: + // * Non MT discovery is enabled at the start of a full GC. + // * Processing and enqueueing during a full GC is non-MT. + // * During a full GC, references are processed after marking. + // + // * Discovery (may or may not be MT) is enabled at the start + // of an incremental evacuation pause. + // * References are processed near the end of a STW evacuation pause. + // * For both types of GC: + // * Discovery is atomic - i.e. not concurrent. + // * Reference discovery will not need a barrier. + + MemRegion mr = reserved_region(); + + // Concurrent Mark ref processor + _ref_processor_cm = + new ReferenceProcessor(mr, // span + ParallelRefProcEnabled && (ParallelGCThreads > 1), + // mt processing + (int) ParallelGCThreads, + // degree of mt processing + (ParallelGCThreads > 1) || (ConcGCThreads > 1), + // mt discovery + (int) MAX2(ParallelGCThreads, ConcGCThreads), + // degree of mt discovery + false, + // Reference discovery is not atomic + &_is_alive_closure_cm); + // is alive closure + // (for efficiency/performance) + + // STW ref processor + _ref_processor_stw = + new ReferenceProcessor(mr, // span + ParallelRefProcEnabled && (ParallelGCThreads > 1), + // mt processing + MAX2((int)ParallelGCThreads, 1), + // degree of mt processing + (ParallelGCThreads > 1), + // mt discovery + MAX2((int)ParallelGCThreads, 1), + // degree of mt discovery + true, + // Reference discovery is atomic + &_is_alive_closure_stw); + // is alive closure + // (for efficiency/performance) +} + +size_t G1CollectedHeap::capacity() const { + return _hrm.length() * HeapRegion::GrainBytes; +} + +void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { + assert(!hr->is_continues_humongous(), "pre-condition"); + hr->reset_gc_time_stamp(); + if (hr->is_starts_humongous()) { + uint first_index = hr->hrm_index() + 1; + uint last_index = hr->last_hc_index(); + for (uint i = first_index; i < last_index; i += 1) { + HeapRegion* chr = region_at(i); + assert(chr->is_continues_humongous(), "sanity"); + chr->reset_gc_time_stamp(); + } + } +} + +#ifndef PRODUCT + +class CheckGCTimeStampsHRClosure : public HeapRegionClosure { +private: + unsigned _gc_time_stamp; + bool _failures; + +public: + CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) : + _gc_time_stamp(gc_time_stamp), _failures(false) { } + + virtual bool doHeapRegion(HeapRegion* hr) { + unsigned region_gc_time_stamp = hr->get_gc_time_stamp(); + if (_gc_time_stamp != region_gc_time_stamp) { + gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, " + "expected %d", HR_FORMAT_PARAMS(hr), + region_gc_time_stamp, _gc_time_stamp); + _failures = true; + } + return false; + } + + bool failures() { return _failures; } +}; + +void G1CollectedHeap::check_gc_time_stamps() { + CheckGCTimeStampsHRClosure cl(_gc_time_stamp); + heap_region_iterate(&cl); + guarantee(!cl.failures(), "all GC time stamps should have been reset"); +} +#endif // PRODUCT + +void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, + DirtyCardQueue* into_cset_dcq, + bool concurrent, + uint worker_i) { + // Clean cards in the hot card cache + G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); + hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq); + + DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); + size_t n_completed_buffers = 0; + while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) { + n_completed_buffers++; + } + g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers); + dcqs.clear_n_completed_buffers(); + assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); +} + + +// Computes the sum of the storage used by the various regions. +size_t G1CollectedHeap::used() const { + return _allocator->used(); +} + +size_t G1CollectedHeap::used_unlocked() const { + return _allocator->used_unlocked(); +} + +class SumUsedClosure: public HeapRegionClosure { + size_t _used; +public: + SumUsedClosure() : _used(0) {} + bool doHeapRegion(HeapRegion* r) { + if (!r->is_continues_humongous()) { + _used += r->used(); + } + return false; + } + size_t result() { return _used; } +}; + +size_t G1CollectedHeap::recalculate_used() const { + double recalculate_used_start = os::elapsedTime(); + + SumUsedClosure blk; + heap_region_iterate(&blk); + + g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); + return blk.result(); +} + +bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { + switch (cause) { + case GCCause::_gc_locker: return GCLockerInvokesConcurrent; + case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; + case GCCause::_g1_humongous_allocation: return true; + case GCCause::_update_allocation_context_stats_inc: return true; + case GCCause::_wb_conc_mark: return true; + default: return false; + } +} + +#ifndef PRODUCT +void G1CollectedHeap::allocate_dummy_regions() { + // Let's fill up most of the region + size_t word_size = HeapRegion::GrainWords - 1024; + // And as a result the region we'll allocate will be humongous. + guarantee(is_humongous(word_size), "sanity"); + + for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { + // Let's use the existing mechanism for the allocation + HeapWord* dummy_obj = humongous_obj_allocate(word_size, + AllocationContext::system()); + if (dummy_obj != NULL) { + MemRegion mr(dummy_obj, word_size); + CollectedHeap::fill_with_object(mr); + } else { + // If we can't allocate once, we probably cannot allocate + // again. Let's get out of the loop. + break; + } + } +} +#endif // !PRODUCT + +void G1CollectedHeap::increment_old_marking_cycles_started() { + assert(_old_marking_cycles_started == _old_marking_cycles_completed || + _old_marking_cycles_started == _old_marking_cycles_completed + 1, + err_msg("Wrong marking cycle count (started: %d, completed: %d)", + _old_marking_cycles_started, _old_marking_cycles_completed)); + + _old_marking_cycles_started++; +} + +void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { + MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); + + // We assume that if concurrent == true, then the caller is a + // concurrent thread that was joined the Suspendible Thread + // Set. If there's ever a cheap way to check this, we should add an + // assert here. + + // Given that this method is called at the end of a Full GC or of a + // concurrent cycle, and those can be nested (i.e., a Full GC can + // interrupt a concurrent cycle), the number of full collections + // completed should be either one (in the case where there was no + // nesting) or two (when a Full GC interrupted a concurrent cycle) + // behind the number of full collections started. + + // This is the case for the inner caller, i.e. a Full GC. + assert(concurrent || + (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || + (_old_marking_cycles_started == _old_marking_cycles_completed + 2), + err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " + "is inconsistent with _old_marking_cycles_completed = %u", + _old_marking_cycles_started, _old_marking_cycles_completed)); + + // This is the case for the outer caller, i.e. the concurrent cycle. + assert(!concurrent || + (_old_marking_cycles_started == _old_marking_cycles_completed + 1), + err_msg("for outer caller (concurrent cycle): " + "_old_marking_cycles_started = %u " + "is inconsistent with _old_marking_cycles_completed = %u", + _old_marking_cycles_started, _old_marking_cycles_completed)); + + _old_marking_cycles_completed += 1; + + // We need to clear the "in_progress" flag in the CM thread before + // we wake up any waiters (especially when ExplicitInvokesConcurrent + // is set) so that if a waiter requests another System.gc() it doesn't + // incorrectly see that a marking cycle is still in progress. + if (concurrent) { + _cmThread->clear_in_progress(); + } + + // This notify_all() will ensure that a thread that called + // System.gc() with (with ExplicitGCInvokesConcurrent set or not) + // and it's waiting for a full GC to finish will be woken up. It is + // waiting in VM_G1IncCollectionPause::doit_epilogue(). + FullGCCount_lock->notify_all(); +} + +void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) { + _concurrent_cycle_started = true; + _gc_timer_cm->register_gc_start(start_time); + + _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start()); + trace_heap_before_gc(_gc_tracer_cm); +} + +void G1CollectedHeap::register_concurrent_cycle_end() { + if (_concurrent_cycle_started) { + if (_cm->has_aborted()) { + _gc_tracer_cm->report_concurrent_mode_failure(); + } + + _gc_timer_cm->register_gc_end(); + _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions()); + + // Clear state variables to prepare for the next concurrent cycle. + _concurrent_cycle_started = false; + _heap_summary_sent = false; + } +} + +void G1CollectedHeap::trace_heap_after_concurrent_cycle() { + if (_concurrent_cycle_started) { + // This function can be called when: + // the cleanup pause is run + // the concurrent cycle is aborted before the cleanup pause. + // the concurrent cycle is aborted after the cleanup pause, + // but before the concurrent cycle end has been registered. + // Make sure that we only send the heap information once. + if (!_heap_summary_sent) { + trace_heap_after_gc(_gc_tracer_cm); + _heap_summary_sent = true; + } + } +} + +G1YCType G1CollectedHeap::yc_type() { + bool is_young = g1_policy()->gcs_are_young(); + bool is_initial_mark = g1_policy()->during_initial_mark_pause(); + bool is_during_mark = mark_in_progress(); + + if (is_initial_mark) { + return InitialMark; + } else if (is_during_mark) { + return DuringMark; + } else if (is_young) { + return Normal; + } else { + return Mixed; + } +} + +void G1CollectedHeap::collect(GCCause::Cause cause) { + assert_heap_not_locked(); + + uint gc_count_before; + uint old_marking_count_before; + uint full_gc_count_before; + bool retry_gc; + + do { + retry_gc = false; + + { + MutexLocker ml(Heap_lock); + + // Read the GC count while holding the Heap_lock + gc_count_before = total_collections(); + full_gc_count_before = total_full_collections(); + old_marking_count_before = _old_marking_cycles_started; + } + + if (should_do_concurrent_full_gc(cause)) { + // Schedule an initial-mark evacuation pause that will start a + // concurrent cycle. We're setting word_size to 0 which means that + // we are not requesting a post-GC allocation. + VM_G1IncCollectionPause op(gc_count_before, + 0, /* word_size */ + true, /* should_initiate_conc_mark */ + g1_policy()->max_pause_time_ms(), + cause); + op.set_allocation_context(AllocationContext::current()); + + VMThread::execute(&op); + if (!op.pause_succeeded()) { + if (old_marking_count_before == _old_marking_cycles_started) { + retry_gc = op.should_retry_gc(); + } else { + // A Full GC happened while we were trying to schedule the + // initial-mark GC. No point in starting a new cycle given + // that the whole heap was collected anyway. + } + + if (retry_gc) { + if (GC_locker::is_active_and_needs_gc()) { + GC_locker::stall_until_clear(); + } + } + } + } else { + if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc + DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { + + // Schedule a standard evacuation pause. We're setting word_size + // to 0 which means that we are not requesting a post-GC allocation. + VM_G1IncCollectionPause op(gc_count_before, + 0, /* word_size */ + false, /* should_initiate_conc_mark */ + g1_policy()->max_pause_time_ms(), + cause); + VMThread::execute(&op); + } else { + // Schedule a Full GC. + VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); + VMThread::execute(&op); + } + } + } while (retry_gc); +} + +bool G1CollectedHeap::is_in(const void* p) const { + if (_hrm.reserved().contains(p)) { + // Given that we know that p is in the reserved space, + // heap_region_containing_raw() should successfully + // return the containing region. + HeapRegion* hr = heap_region_containing_raw(p); + return hr->is_in(p); + } else { + return false; + } +} + +#ifdef ASSERT +bool G1CollectedHeap::is_in_exact(const void* p) const { + bool contains = reserved_region().contains(p); + bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); + if (contains && available) { + return true; + } else { + return false; + } +} +#endif + +// Iteration functions. + +// Applies an ExtendedOopClosure onto all references of objects within a HeapRegion. + +class IterateOopClosureRegionClosure: public HeapRegionClosure { + ExtendedOopClosure* _cl; +public: + IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {} + bool doHeapRegion(HeapRegion* r) { + if (!r->is_continues_humongous()) { + r->oop_iterate(_cl); + } + return false; + } +}; + +// Iterates an ObjectClosure over all objects within a HeapRegion. + +class IterateObjectClosureRegionClosure: public HeapRegionClosure { + ObjectClosure* _cl; +public: + IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} + bool doHeapRegion(HeapRegion* r) { + if (!r->is_continues_humongous()) { + r->object_iterate(_cl); + } + return false; + } +}; + +void G1CollectedHeap::object_iterate(ObjectClosure* cl) { + IterateObjectClosureRegionClosure blk(cl); + heap_region_iterate(&blk); +} + +void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { + _hrm.iterate(cl); +} + +void +G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl, + uint worker_id, + HeapRegionClaimer *hrclaimer, + bool concurrent) const { + _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent); +} + +// Clear the cached CSet starting regions and (more importantly) +// the time stamps. Called when we reset the GC time stamp. +void G1CollectedHeap::clear_cset_start_regions() { + assert(_worker_cset_start_region != NULL, "sanity"); + assert(_worker_cset_start_region_time_stamp != NULL, "sanity"); + + int n_queues = MAX2((int)ParallelGCThreads, 1); + for (int i = 0; i < n_queues; i++) { + _worker_cset_start_region[i] = NULL; + _worker_cset_start_region_time_stamp[i] = 0; + } +} + +// Given the id of a worker, obtain or calculate a suitable +// starting region for iterating over the current collection set. +HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) { + assert(get_gc_time_stamp() > 0, "should have been updated by now"); + + HeapRegion* result = NULL; + unsigned gc_time_stamp = get_gc_time_stamp(); + + if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) { + // Cached starting region for current worker was set + // during the current pause - so it's valid. + // Note: the cached starting heap region may be NULL + // (when the collection set is empty). + result = _worker_cset_start_region[worker_i]; + assert(result == NULL || result->in_collection_set(), "sanity"); + return result; + } + + // The cached entry was not valid so let's calculate + // a suitable starting heap region for this worker. + + // We want the parallel threads to start their collection + // set iteration at different collection set regions to + // avoid contention. + // If we have: + // n collection set regions + // p threads + // Then thread t will start at region floor ((t * n) / p) + + result = g1_policy()->collection_set(); + uint cs_size = g1_policy()->cset_region_length(); + uint active_workers = workers()->active_workers(); + assert(UseDynamicNumberOfGCThreads || + active_workers == workers()->total_workers(), + "Unless dynamic should use total workers"); + + uint end_ind = (cs_size * worker_i) / active_workers; + uint start_ind = 0; + + if (worker_i > 0 && + _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) { + // Previous workers starting region is valid + // so let's iterate from there + start_ind = (cs_size * (worker_i - 1)) / active_workers; + result = _worker_cset_start_region[worker_i - 1]; + } + + for (uint i = start_ind; i < end_ind; i++) { + result = result->next_in_collection_set(); + } + + // Note: the calculated starting heap region may be NULL + // (when the collection set is empty). + assert(result == NULL || result->in_collection_set(), "sanity"); + assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp, + "should be updated only once per pause"); + _worker_cset_start_region[worker_i] = result; + OrderAccess::storestore(); + _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp; + return result; +} + +void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { + HeapRegion* r = g1_policy()->collection_set(); + while (r != NULL) { + HeapRegion* next = r->next_in_collection_set(); + if (cl->doHeapRegion(r)) { + cl->incomplete(); + return; + } + r = next; + } +} + +void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r, + HeapRegionClosure *cl) { + if (r == NULL) { + // The CSet is empty so there's nothing to do. + return; + } + + assert(r->in_collection_set(), + "Start region must be a member of the collection set."); + HeapRegion* cur = r; + while (cur != NULL) { + HeapRegion* next = cur->next_in_collection_set(); + if (cl->doHeapRegion(cur) && false) { + cl->incomplete(); + return; + } + cur = next; + } + cur = g1_policy()->collection_set(); + while (cur != r) { + HeapRegion* next = cur->next_in_collection_set(); + if (cl->doHeapRegion(cur) && false) { + cl->incomplete(); + return; + } + cur = next; + } +} + +HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { + HeapRegion* result = _hrm.next_region_in_heap(from); + while (result != NULL && result->is_humongous()) { + result = _hrm.next_region_in_heap(result); + } + return result; +} + +HeapWord* G1CollectedHeap::block_start(const void* addr) const { + HeapRegion* hr = heap_region_containing(addr); + return hr->block_start(addr); +} + +size_t G1CollectedHeap::block_size(const HeapWord* addr) const { + HeapRegion* hr = heap_region_containing(addr); + return hr->block_size(addr); +} + +bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { + HeapRegion* hr = heap_region_containing(addr); + return hr->block_is_obj(addr); +} + +bool G1CollectedHeap::supports_tlab_allocation() const { + return true; +} + +size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { + return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes; +} + +size_t G1CollectedHeap::tlab_used(Thread* ignored) const { + return young_list()->eden_used_bytes(); +} + +// For G1 TLABs should not contain humongous objects, so the maximum TLAB size +// must be smaller than the humongous object limit. +size_t G1CollectedHeap::max_tlab_size() const { + return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment); +} + +size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { + // Return the remaining space in the cur alloc region, but not less than + // the min TLAB size. + + // Also, this value can be at most the humongous object threshold, + // since we can't allow tlabs to grow big enough to accommodate + // humongous objects. + + HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get(); + size_t max_tlab = max_tlab_size() * wordSize; + if (hr == NULL) { + return max_tlab; + } else { + return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab); + } +} + +size_t G1CollectedHeap::max_capacity() const { + return _hrm.reserved().byte_size(); +} + +jlong G1CollectedHeap::millis_since_last_gc() { + // assert(false, "NYI"); + return 0; +} + +void G1CollectedHeap::prepare_for_verify() { + if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) { + ensure_parsability(false); + } + g1_rem_set()->prepare_for_verify(); +} + +bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr, + VerifyOption vo) { + switch (vo) { + case VerifyOption_G1UsePrevMarking: + return hr->obj_allocated_since_prev_marking(obj); + case VerifyOption_G1UseNextMarking: + return hr->obj_allocated_since_next_marking(obj); + case VerifyOption_G1UseMarkWord: + return false; + default: + ShouldNotReachHere(); + } + return false; // keep some compilers happy +} + +HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) { + switch (vo) { + case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start(); + case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start(); + case VerifyOption_G1UseMarkWord: return NULL; + default: ShouldNotReachHere(); + } + return NULL; // keep some compilers happy +} + +bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) { + switch (vo) { + case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj); + case VerifyOption_G1UseNextMarking: return isMarkedNext(obj); + case VerifyOption_G1UseMarkWord: return obj->is_gc_marked(); + default: ShouldNotReachHere(); + } + return false; // keep some compilers happy +} + +const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) { + switch (vo) { + case VerifyOption_G1UsePrevMarking: return "PTAMS"; + case VerifyOption_G1UseNextMarking: return "NTAMS"; + case VerifyOption_G1UseMarkWord: return "NONE"; + default: ShouldNotReachHere(); + } + return NULL; // keep some compilers happy +} + +class VerifyRootsClosure: public OopClosure { +private: + G1CollectedHeap* _g1h; + VerifyOption _vo; + bool _failures; +public: + // _vo == UsePrevMarking -> use "prev" marking information, + // _vo == UseNextMarking -> use "next" marking information, + // _vo == UseMarkWord -> use mark word from object header. + VerifyRootsClosure(VerifyOption vo) : + _g1h(G1CollectedHeap::heap()), + _vo(vo), + _failures(false) { } + + bool failures() { return _failures; } + + template void do_oop_nv(T* p) { + T heap_oop = oopDesc::load_heap_oop(p); + if (!oopDesc::is_null(heap_oop)) { + oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); + if (_g1h->is_obj_dead_cond(obj, _vo)) { + gclog_or_tty->print_cr("Root location "PTR_FORMAT" " + "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj)); + if (_vo == VerifyOption_G1UseMarkWord) { + gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark()); + } + obj->print_on(gclog_or_tty); + _failures = true; + } + } + } + + void do_oop(oop* p) { do_oop_nv(p); } + void do_oop(narrowOop* p) { do_oop_nv(p); } +}; + +class G1VerifyCodeRootOopClosure: public OopClosure { + G1CollectedHeap* _g1h; + OopClosure* _root_cl; + nmethod* _nm; + VerifyOption _vo; + bool _failures; + + template void do_oop_work(T* p) { + // First verify that this root is live + _root_cl->do_oop(p); + + if (!G1VerifyHeapRegionCodeRoots) { + // We're not verifying the code roots attached to heap region. + return; + } + + // Don't check the code roots during marking verification in a full GC + if (_vo == VerifyOption_G1UseMarkWord) { + return; + } + + // Now verify that the current nmethod (which contains p) is + // in the code root list of the heap region containing the + // object referenced by p. + + T heap_oop = oopDesc::load_heap_oop(p); + if (!oopDesc::is_null(heap_oop)) { + oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); + + // Now fetch the region containing the object + HeapRegion* hr = _g1h->heap_region_containing(obj); + HeapRegionRemSet* hrrs = hr->rem_set(); + // Verify that the strong code root list for this region + // contains the nmethod + if (!hrrs->strong_code_roots_list_contains(_nm)) { + gclog_or_tty->print_cr("Code root location "PTR_FORMAT" " + "from nmethod "PTR_FORMAT" not in strong " + "code roots for region ["PTR_FORMAT","PTR_FORMAT")", + p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end())); + _failures = true; + } + } + } + +public: + G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo): + _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {} + + void do_oop(oop* p) { do_oop_work(p); } + void do_oop(narrowOop* p) { do_oop_work(p); } + + void set_nmethod(nmethod* nm) { _nm = nm; } + bool failures() { return _failures; } +}; + +class G1VerifyCodeRootBlobClosure: public CodeBlobClosure { + G1VerifyCodeRootOopClosure* _oop_cl; + +public: + G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl): + _oop_cl(oop_cl) {} + + void do_code_blob(CodeBlob* cb) { + nmethod* nm = cb->as_nmethod_or_null(); + if (nm != NULL) { + _oop_cl->set_nmethod(nm); + nm->oops_do(_oop_cl); + } + } +}; + +class YoungRefCounterClosure : public OopClosure { + G1CollectedHeap* _g1h; + int _count; + public: + YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {} + void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } } + void do_oop(narrowOop* p) { ShouldNotReachHere(); } + + int count() { return _count; } + void reset_count() { _count = 0; }; +}; + +class VerifyKlassClosure: public KlassClosure { + YoungRefCounterClosure _young_ref_counter_closure; + OopClosure *_oop_closure; + public: + VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {} + void do_klass(Klass* k) { + k->oops_do(_oop_closure); + + _young_ref_counter_closure.reset_count(); + k->oops_do(&_young_ref_counter_closure); + if (_young_ref_counter_closure.count() > 0) { + guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k))); + } + } +}; + +class VerifyLivenessOopClosure: public OopClosure { + G1CollectedHeap* _g1h; + VerifyOption _vo; +public: + VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo): + _g1h(g1h), _vo(vo) + { } + void do_oop(narrowOop *p) { do_oop_work(p); } + void do_oop( oop *p) { do_oop_work(p); } + + template void do_oop_work(T *p) { + oop obj = oopDesc::load_decode_heap_oop(p); + guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo), + "Dead object referenced by a not dead object"); + } +}; + +class VerifyObjsInRegionClosure: public ObjectClosure { +private: + G1CollectedHeap* _g1h; + size_t _live_bytes; + HeapRegion *_hr; + VerifyOption _vo; +public: + // _vo == UsePrevMarking -> use "prev" marking information, + // _vo == UseNextMarking -> use "next" marking information, + // _vo == UseMarkWord -> use mark word from object header. + VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo) + : _live_bytes(0), _hr(hr), _vo(vo) { + _g1h = G1CollectedHeap::heap(); + } + void do_object(oop o) { + VerifyLivenessOopClosure isLive(_g1h, _vo); + assert(o != NULL, "Huh?"); + if (!_g1h->is_obj_dead_cond(o, _vo)) { + // If the object is alive according to the mark word, + // then verify that the marking information agrees. + // Note we can't verify the contra-positive of the + // above: if the object is dead (according to the mark + // word), it may not be marked, or may have been marked + // but has since became dead, or may have been allocated + // since the last marking. + if (_vo == VerifyOption_G1UseMarkWord) { + guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch"); + } + + o->oop_iterate_no_header(&isLive); + if (!_hr->obj_allocated_since_prev_marking(o)) { + size_t obj_size = o->size(); // Make sure we don't overflow + _live_bytes += (obj_size * HeapWordSize); + } + } + } + size_t live_bytes() { return _live_bytes; } +}; + +class VerifyRegionClosure: public HeapRegionClosure { +private: + bool _par; + VerifyOption _vo; + bool _failures; +public: + // _vo == UsePrevMarking -> use "prev" marking information, + // _vo == UseNextMarking -> use "next" marking information, + // _vo == UseMarkWord -> use mark word from object header. + VerifyRegionClosure(bool par, VerifyOption vo) + : _par(par), + _vo(vo), + _failures(false) {} + + bool failures() { + return _failures; + } + + bool doHeapRegion(HeapRegion* r) { + if (!r->is_continues_humongous()) { + bool failures = false; + r->verify(_vo, &failures); + if (failures) { + _failures = true; + } else { + VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo); + r->object_iterate(¬_dead_yet_cl); + if (_vo != VerifyOption_G1UseNextMarking) { + if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) { + gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] " + "max_live_bytes "SIZE_FORMAT" " + "< calculated "SIZE_FORMAT, + p2i(r->bottom()), p2i(r->end()), + r->max_live_bytes(), + not_dead_yet_cl.live_bytes()); + _failures = true; + } + } else { + // When vo == UseNextMarking we cannot currently do a sanity + // check on the live bytes as the calculation has not been + // finalized yet. + } + } + } + return false; // stop the region iteration if we hit a failure + } +}; + +// This is the task used for parallel verification of the heap regions + +class G1ParVerifyTask: public AbstractGangTask { +private: + G1CollectedHeap* _g1h; + VerifyOption _vo; + bool _failures; + HeapRegionClaimer _hrclaimer; + +public: + // _vo == UsePrevMarking -> use "prev" marking information, + // _vo == UseNextMarking -> use "next" marking information, + // _vo == UseMarkWord -> use mark word from object header. + G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) : + AbstractGangTask("Parallel verify task"), + _g1h(g1h), + _vo(vo), + _failures(false), + _hrclaimer(g1h->workers()->active_workers()) {} + + bool failures() { + return _failures; + } + + void work(uint worker_id) { + HandleMark hm; + VerifyRegionClosure blk(true, _vo); + _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer); + if (blk.failures()) { + _failures = true; + } + } +}; + +void G1CollectedHeap::verify(bool silent, VerifyOption vo) { + if (SafepointSynchronize::is_at_safepoint()) { + assert(Thread::current()->is_VM_thread(), + "Expected to be executed serially by the VM thread at this point"); + + if (!silent) { gclog_or_tty->print("Roots "); } + VerifyRootsClosure rootsCl(vo); + VerifyKlassClosure klassCl(this, &rootsCl); + CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false); + + // We apply the relevant closures to all the oops in the + // system dictionary, class loader data graph, the string table + // and the nmethods in the code cache. + G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo); + G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl); + + { + G1RootProcessor root_processor(this); + root_processor.process_all_roots(&rootsCl, + &cldCl, + &blobsCl); + } + + bool failures = rootsCl.failures() || codeRootsCl.failures(); + + if (vo != VerifyOption_G1UseMarkWord) { + // If we're verifying during a full GC then the region sets + // will have been torn down at the start of the GC. Therefore + // verifying the region sets will fail. So we only verify + // the region sets when not in a full GC. + if (!silent) { gclog_or_tty->print("HeapRegionSets "); } + verify_region_sets(); + } + + if (!silent) { gclog_or_tty->print("HeapRegions "); } + if (GCParallelVerificationEnabled && ParallelGCThreads > 1) { + + G1ParVerifyTask task(this, vo); + assert(UseDynamicNumberOfGCThreads || + workers()->active_workers() == workers()->total_workers(), + "If not dynamic should be using all the workers"); + uint n_workers = workers()->active_workers(); + set_par_threads(n_workers); + workers()->run_task(&task); + set_par_threads(0); + if (task.failures()) { + failures = true; + } + + } else { + VerifyRegionClosure blk(false, vo); + heap_region_iterate(&blk); + if (blk.failures()) { + failures = true; + } + } + + if (G1StringDedup::is_enabled()) { + if (!silent) gclog_or_tty->print("StrDedup "); + G1StringDedup::verify(); + } + + if (failures) { + gclog_or_tty->print_cr("Heap:"); + // It helps to have the per-region information in the output to + // help us track down what went wrong. This is why we call + // print_extended_on() instead of print_on(). + print_extended_on(gclog_or_tty); + gclog_or_tty->cr(); + gclog_or_tty->flush(); + } + guarantee(!failures, "there should not have been any failures"); + } else { + if (!silent) { + gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet"); + if (G1StringDedup::is_enabled()) { + gclog_or_tty->print(", StrDedup"); + } + gclog_or_tty->print(") "); + } + } +} + +void G1CollectedHeap::verify(bool silent) { + verify(silent, VerifyOption_G1UsePrevMarking); +} + +double G1CollectedHeap::verify(bool guard, const char* msg) { + double verify_time_ms = 0.0; + + if (guard && total_collections() >= VerifyGCStartAt) { + double verify_start = os::elapsedTime(); + HandleMark hm; // Discard invalid handles created during verification + prepare_for_verify(); + Universe::verify(VerifyOption_G1UsePrevMarking, msg); + verify_time_ms = (os::elapsedTime() - verify_start) * 1000; + } + + return verify_time_ms; +} + +void G1CollectedHeap::verify_before_gc() { + double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:"); + g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms); +} + +void G1CollectedHeap::verify_after_gc() { + double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:"); + g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms); +} + +class PrintRegionClosure: public HeapRegionClosure { + outputStream* _st; +public: + PrintRegionClosure(outputStream* st) : _st(st) {} + bool doHeapRegion(HeapRegion* r) { + r->print_on(_st); + return false; + } +}; + +bool G1CollectedHeap::is_obj_dead_cond(const oop obj, + const HeapRegion* hr, + const VerifyOption vo) const { + switch (vo) { + case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); + case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); + case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); + default: ShouldNotReachHere(); + } + return false; // keep some compilers happy +} + +bool G1CollectedHeap::is_obj_dead_cond(const oop obj, + const VerifyOption vo) const { + switch (vo) { + case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); + case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); + case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); + default: ShouldNotReachHere(); + } + return false; // keep some compilers happy +} + +void G1CollectedHeap::print_on(outputStream* st) const { + st->print(" %-20s", "garbage-first heap"); + st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", + capacity()/K, used_unlocked()/K); + st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", + p2i(_hrm.reserved().start()), + p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords), + p2i(_hrm.reserved().end())); + st->cr(); + st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); + uint young_regions = _young_list->length(); + st->print("%u young (" SIZE_FORMAT "K), ", young_regions, + (size_t) young_regions * HeapRegion::GrainBytes / K); + uint survivor_regions = g1_policy()->recorded_survivor_regions(); + st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, + (size_t) survivor_regions * HeapRegion::GrainBytes / K); + st->cr(); + MetaspaceAux::print_on(st); +} + +void G1CollectedHeap::print_extended_on(outputStream* st) const { + print_on(st); + + // Print the per-region information. + st->cr(); + st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), " + "HS=humongous(starts), HC=humongous(continues), " + "CS=collection set, F=free, TS=gc time stamp, " + "PTAMS=previous top-at-mark-start, " + "NTAMS=next top-at-mark-start)"); + PrintRegionClosure blk(st); + heap_region_iterate(&blk); +} + +void G1CollectedHeap::print_on_error(outputStream* st) const { + this->CollectedHeap::print_on_error(st); + + if (_cm != NULL) { + st->cr(); + _cm->print_on_error(st); + } +} + +void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { + workers()->print_worker_threads_on(st); + _cmThread->print_on(st); + st->cr(); + _cm->print_worker_threads_on(st); + _cg1r->print_worker_threads_on(st); + if (G1StringDedup::is_enabled()) { + G1StringDedup::print_worker_threads_on(st); + } +} + +void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { + workers()->threads_do(tc); + tc->do_thread(_cmThread); + _cg1r->threads_do(tc); + if (G1StringDedup::is_enabled()) { + G1StringDedup::threads_do(tc); + } +} + +void G1CollectedHeap::print_tracing_info() const { + // We'll overload this to mean "trace GC pause statistics." + if (TraceYoungGenTime || TraceOldGenTime) { + // The "G1CollectorPolicy" is keeping track of these stats, so delegate + // to that. + g1_policy()->print_tracing_info(); + } + if (G1SummarizeRSetStats) { + g1_rem_set()->print_summary_info(); + } + if (G1SummarizeConcMark) { + concurrent_mark()->print_summary_info(); + } + g1_policy()->print_yg_surv_rate_info(); +} + +#ifndef PRODUCT +// Helpful for debugging RSet issues. + +class PrintRSetsClosure : public HeapRegionClosure { +private: + const char* _msg; + size_t _occupied_sum; + +public: + bool doHeapRegion(HeapRegion* r) { + HeapRegionRemSet* hrrs = r->rem_set(); + size_t occupied = hrrs->occupied(); + _occupied_sum += occupied; + + gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT, + HR_FORMAT_PARAMS(r)); + if (occupied == 0) { + gclog_or_tty->print_cr(" RSet is empty"); + } else { + hrrs->print(); + } + gclog_or_tty->print_cr("----------"); + return false; + } + + PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { + gclog_or_tty->cr(); + gclog_or_tty->print_cr("========================================"); + gclog_or_tty->print_cr("%s", msg); + gclog_or_tty->cr(); + } + + ~PrintRSetsClosure() { + gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum); + gclog_or_tty->print_cr("========================================"); + gclog_or_tty->cr(); + } +}; + +void G1CollectedHeap::print_cset_rsets() { + PrintRSetsClosure cl("Printing CSet RSets"); + collection_set_iterate(&cl); +} + +void G1CollectedHeap::print_all_rsets() { + PrintRSetsClosure cl("Printing All RSets");; + heap_region_iterate(&cl); +} +#endif // PRODUCT + +G1CollectedHeap* G1CollectedHeap::heap() { + CollectedHeap* heap = Universe::heap(); + assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); + assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap"); + return (G1CollectedHeap*)heap; +} + +void G1CollectedHeap::gc_prologue(bool full /* Ignored */) { + // always_do_update_barrier = false; + assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); + // Fill TLAB's and such + accumulate_statistics_all_tlabs(); + ensure_parsability(true); + + if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) && + (total_collections() % G1SummarizeRSetStatsPeriod == 0)) { + g1_rem_set()->print_periodic_summary_info("Before GC RS summary"); + } +} + +void G1CollectedHeap::gc_epilogue(bool full) { + + if (G1SummarizeRSetStats && + (G1SummarizeRSetStatsPeriod > 0) && + // we are at the end of the GC. Total collections has already been increased. + ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) { + g1_rem_set()->print_periodic_summary_info("After GC RS summary"); + } + + // FIXME: what is this about? + // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" + // is set. + COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(), + "derived pointer present")); + // always_do_update_barrier = true; + + resize_all_tlabs(); + allocation_context_stats().update(full); + + // We have just completed a GC. Update the soft reference + // policy with the new heap occupancy + Universe::update_heap_info_at_gc(); +} + +HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, + uint gc_count_before, + bool* succeeded, + GCCause::Cause gc_cause) { + assert_heap_not_locked_and_not_at_safepoint(); + g1_policy()->record_stop_world_start(); + VM_G1IncCollectionPause op(gc_count_before, + word_size, + false, /* should_initiate_conc_mark */ + g1_policy()->max_pause_time_ms(), + gc_cause); + + op.set_allocation_context(AllocationContext::current()); + VMThread::execute(&op); + + HeapWord* result = op.result(); + bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); + assert(result == NULL || ret_succeeded, + "the result should be NULL if the VM did not succeed"); + *succeeded = ret_succeeded; + + assert_heap_not_locked(); + return result; +} + +void +G1CollectedHeap::doConcurrentMark() { + MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); + if (!_cmThread->in_progress()) { + _cmThread->set_started(); + CGC_lock->notify(); + } +} + +size_t G1CollectedHeap::pending_card_num() { + size_t extra_cards = 0; + JavaThread *curr = Threads::first(); + while (curr != NULL) { + DirtyCardQueue& dcq = curr->dirty_card_queue(); + extra_cards += dcq.size(); + curr = curr->next(); + } + DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); + size_t buffer_size = dcqs.buffer_size(); + size_t buffer_num = dcqs.completed_buffers_num(); + + // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes + // in bytes - not the number of 'entries'. We need to convert + // into a number of cards. + return (buffer_size * buffer_num + extra_cards) / oopSize; +} + +size_t G1CollectedHeap::cards_scanned() { + return g1_rem_set()->cardsScanned(); +} + +class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { + private: + size_t _total_humongous; + size_t _candidate_humongous; + + DirtyCardQueue _dcq; + + // We don't nominate objects with many remembered set entries, on + // the assumption that such objects are likely still live. + bool is_remset_small(HeapRegion* region) const { + HeapRegionRemSet* const rset = region->rem_set(); + return G1EagerReclaimHumongousObjectsWithStaleRefs + ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) + : rset->is_empty(); + } + + bool is_typeArray_region(HeapRegion* region) const { + return oop(region->bottom())->is_typeArray(); + } + + bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { + assert(region->is_starts_humongous(), "Must start a humongous object"); + + // Candidate selection must satisfy the following constraints + // while concurrent marking is in progress: + // + // * In order to maintain SATB invariants, an object must not be + // reclaimed if it was allocated before the start of marking and + // has not had its references scanned. Such an object must have + // its references (including type metadata) scanned to ensure no + // live objects are missed by the marking process. Objects + // allocated after the start of concurrent marking don't need to + // be scanned. + // + // * An object must not be reclaimed if it is on the concurrent + // mark stack. Objects allocated after the start of concurrent + // marking are never pushed on the mark stack. + // + // Nominating only objects allocated after the start of concurrent + // marking is sufficient to meet both constraints. This may miss + // some objects that satisfy the constraints, but the marking data + // structures don't support efficiently performing the needed + // additional tests or scrubbing of the mark stack. + // + // However, we presently only nominate is_typeArray() objects. + // A humongous object containing references induces remembered + // set entries on other regions. In order to reclaim such an + // object, those remembered sets would need to be cleaned up. + // + // We also treat is_typeArray() objects specially, allowing them + // to be reclaimed even if allocated before the start of + // concurrent mark. For this we rely on mark stack insertion to + // exclude is_typeArray() objects, preventing reclaiming an object + // that is in the mark stack. We also rely on the metadata for + // such objects to be built-in and so ensured to be kept live. + // Frequent allocation and drop of large binary blobs is an + // important use case for eager reclaim, and this special handling + // may reduce needed headroom. + + return is_typeArray_region(region) && is_remset_small(region); + } + + public: + RegisterHumongousWithInCSetFastTestClosure() + : _total_humongous(0), + _candidate_humongous(0), + _dcq(&JavaThread::dirty_card_queue_set()) { + } + + virtual bool doHeapRegion(HeapRegion* r) { + if (!r->is_starts_humongous()) { + return false; + } + G1CollectedHeap* g1h = G1CollectedHeap::heap(); + + bool is_candidate = humongous_region_is_candidate(g1h, r); + uint rindex = r->hrm_index(); + g1h->set_humongous_reclaim_candidate(rindex, is_candidate); + if (is_candidate) { + _candidate_humongous++; + g1h->register_humongous_region_with_cset(rindex); + // Is_candidate already filters out humongous object with large remembered sets. + // If we have a humongous object with a few remembered sets, we simply flush these + // remembered set entries into the DCQS. That will result in automatic + // re-evaluation of their remembered set entries during the following evacuation + // phase. + if (!r->rem_set()->is_empty()) { + guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), + "Found a not-small remembered set here. This is inconsistent with previous assumptions."); + G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set(); + HeapRegionRemSetIterator hrrs(r->rem_set()); + size_t card_index; + while (hrrs.has_next(card_index)) { + jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index); + // The remembered set might contain references to already freed + // regions. Filter out such entries to avoid failing card table + // verification. + if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) { + if (*card_ptr != CardTableModRefBS::dirty_card_val()) { + *card_ptr = CardTableModRefBS::dirty_card_val(); + _dcq.enqueue(card_ptr); + } + } + } + r->rem_set()->clear_locked(); + } + assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); + } + _total_humongous++; + + return false; + } + + size_t total_humongous() const { return _total_humongous; } + size_t candidate_humongous() const { return _candidate_humongous; } + + void flush_rem_set_entries() { _dcq.flush(); } +}; + +void G1CollectedHeap::register_humongous_regions_with_cset() { + if (!G1EagerReclaimHumongousObjects) { + g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); + return; + } + double time = os::elapsed_counter(); + + // Collect reclaim candidate information and register candidates with cset. + RegisterHumongousWithInCSetFastTestClosure cl; + heap_region_iterate(&cl); + + time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; + g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, + cl.total_humongous(), + cl.candidate_humongous()); + _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; + + // Finally flush all remembered set entries to re-check into the global DCQS. + cl.flush_rem_set_entries(); +} + +void +G1CollectedHeap::setup_surviving_young_words() { + assert(_surviving_young_words == NULL, "pre-condition"); + uint array_length = g1_policy()->young_cset_region_length(); + _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC); + if (_surviving_young_words == NULL) { + vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR, + "Not enough space for young surv words summary."); + } + memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t)); +#ifdef ASSERT + for (uint i = 0; i < array_length; ++i) { + assert( _surviving_young_words[i] == 0, "memset above" ); + } +#endif // !ASSERT +} + +void +G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) { + MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); + uint array_length = g1_policy()->young_cset_region_length(); + for (uint i = 0; i < array_length; ++i) { + _surviving_young_words[i] += surv_young_words[i]; + } +} + +void +G1CollectedHeap::cleanup_surviving_young_words() { + guarantee( _surviving_young_words != NULL, "pre-condition" ); + FREE_C_HEAP_ARRAY(size_t, _surviving_young_words); + _surviving_young_words = NULL; +} + +#ifdef ASSERT +class VerifyCSetClosure: public HeapRegionClosure { +public: + bool doHeapRegion(HeapRegion* hr) { + // Here we check that the CSet region's RSet is ready for parallel + // iteration. The fields that we'll verify are only manipulated + // when the region is part of a CSet and is collected. Afterwards, + // we reset these fields when we clear the region's RSet (when the + // region is freed) so they are ready when the region is + // re-allocated. The only exception to this is if there's an + // evacuation failure and instead of freeing the region we leave + // it in the heap. In that case, we reset these fields during + // evacuation failure handling. + guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification"); + + // Here's a good place to add any other checks we'd like to + // perform on CSet regions. + return false; + } +}; +#endif // ASSERT + +#if TASKQUEUE_STATS +void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { + st->print_raw_cr("GC Task Stats"); + st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); + st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); +} + +void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const { + print_taskqueue_stats_hdr(st); + + TaskQueueStats totals; + const uint n = workers()->total_workers(); + for (uint i = 0; i < n; ++i) { + st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); + totals += task_queue(i)->stats; + } + st->print_raw("tot "); totals.print(st); st->cr(); + + DEBUG_ONLY(totals.verify()); +} + +void G1CollectedHeap::reset_taskqueue_stats() { + const uint n = workers()->total_workers(); + for (uint i = 0; i < n; ++i) { + task_queue(i)->stats.reset(); + } +} +#endif // TASKQUEUE_STATS + +void G1CollectedHeap::log_gc_header() { + if (!G1Log::fine()) { + return; + } + + gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id()); + + GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause()) + .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)") + .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : ""); + + gclog_or_tty->print("[%s", (const char*)gc_cause_str); +} + +void G1CollectedHeap::log_gc_footer(double pause_time_sec) { + if (!G1Log::fine()) { + return; + } + + if (G1Log::finer()) { + if (evacuation_failed()) { + gclog_or_tty->print(" (to-space exhausted)"); + } + gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); + g1_policy()->phase_times()->note_gc_end(); + g1_policy()->phase_times()->print(pause_time_sec); + g1_policy()->print_detailed_heap_transition(); + } else { + if (evacuation_failed()) { + gclog_or_tty->print("--"); + } + g1_policy()->print_heap_transition(); + gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec); + } + gclog_or_tty->flush(); +} + +bool +G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { + assert_at_safepoint(true /* should_be_vm_thread */); + guarantee(!is_gc_active(), "collection is not reentrant"); + + if (GC_locker::check_active_before_gc()) { + return false; + } + + _gc_timer_stw->register_gc_start(); + + _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); + + SvcGCMarker sgcm(SvcGCMarker::MINOR); + ResourceMark rm; + + G1Log::update_level(); + print_heap_before_gc(); + trace_heap_before_gc(_gc_tracer_stw); + + verify_region_sets_optional(); + verify_dirty_young_regions(); + + // This call will decide whether this pause is an initial-mark + // pause. If it is, during_initial_mark_pause() will return true + // for the duration of this pause. + g1_policy()->decide_on_conc_mark_initiation(); + + // We do not allow initial-mark to be piggy-backed on a mixed GC. + assert(!g1_policy()->during_initial_mark_pause() || + g1_policy()->gcs_are_young(), "sanity"); + + // We also do not allow mixed GCs during marking. + assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity"); + + // Record whether this pause is an initial mark. When the current + // thread has completed its logging output and it's safe to signal + // the CM thread, the flag's value in the policy has been reset. + bool should_start_conc_mark = g1_policy()->during_initial_mark_pause(); + + // Inner scope for scope based logging, timers, and stats collection + { + EvacuationInfo evacuation_info; + + if (g1_policy()->during_initial_mark_pause()) { + // We are about to start a marking cycle, so we increment the + // full collection counter. + increment_old_marking_cycles_started(); + register_concurrent_cycle_start(_gc_timer_stw->gc_start()); + } + + _gc_tracer_stw->report_yc_type(yc_type()); + + TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); + + uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), + workers()->active_workers(), + Threads::number_of_non_daemon_threads()); + assert(UseDynamicNumberOfGCThreads || + active_workers == workers()->total_workers(), + "If not dynamic should be using all the workers"); + workers()->set_active_workers(active_workers); + + double pause_start_sec = os::elapsedTime(); + g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress()); + log_gc_header(); + + TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); + TraceMemoryManagerStats tms(false /* fullGC */, gc_cause()); + + // If the secondary_free_list is not empty, append it to the + // free_list. No need to wait for the cleanup operation to finish; + // the region allocation code will check the secondary_free_list + // and wait if necessary. If the G1StressConcRegionFreeing flag is + // set, skip this step so that the region allocation code has to + // get entries from the secondary_free_list. + if (!G1StressConcRegionFreeing) { + append_secondary_free_list_if_not_empty_with_lock(); + } + + assert(check_young_list_well_formed(), "young list should be well formed"); + + // Don't dynamically change the number of GC threads this early. A value of + // 0 is used to indicate serial work. When parallel work is done, + // it will be set. + + { // Call to jvmpi::post_class_unload_events must occur outside of active GC + IsGCActiveMark x; + + gc_prologue(false); + increment_total_collections(false /* full gc */); + increment_gc_time_stamp(); + + verify_before_gc(); + + check_bitmaps("GC Start"); + + COMPILER2_PRESENT(DerivedPointerTable::clear()); + + // Please see comment in g1CollectedHeap.hpp and + // G1CollectedHeap::ref_processing_init() to see how + // reference processing currently works in G1. + + // Enable discovery in the STW reference processor + ref_processor_stw()->enable_discovery(); + + { + // We want to temporarily turn off discovery by the + // CM ref processor, if necessary, and turn it back on + // on again later if we do. Using a scoped + // NoRefDiscovery object will do this. + NoRefDiscovery no_cm_discovery(ref_processor_cm()); + + // Forget the current alloc region (we might even choose it to be part + // of the collection set!). + _allocator->release_mutator_alloc_region(); + + // We should call this after we retire the mutator alloc + // region(s) so that all the ALLOC / RETIRE events are generated + // before the start GC event. + _hr_printer.start_gc(false /* full */, (size_t) total_collections()); + + // This timing is only used by the ergonomics to handle our pause target. + // It is unclear why this should not include the full pause. We will + // investigate this in CR 7178365. + // + // Preserving the old comment here if that helps the investigation: + // + // The elapsed time induced by the start time below deliberately elides + // the possible verification above. + double sample_start_time_sec = os::elapsedTime(); + +#if YOUNG_LIST_VERBOSE + gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:"); + _young_list->print(); + g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); +#endif // YOUNG_LIST_VERBOSE + + g1_policy()->record_collection_pause_start(sample_start_time_sec); + + double scan_wait_start = os::elapsedTime(); + // We have to wait until the CM threads finish scanning the + // root regions as it's the only way to ensure that all the + // objects on them have been correctly scanned before we start + // moving them during the GC. + bool waited = _cm->root_regions()->wait_until_scan_finished(); + double wait_time_ms = 0.0; + if (waited) { + double scan_wait_end = os::elapsedTime(); + wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; + } + g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); + +#if YOUNG_LIST_VERBOSE + gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:"); + _young_list->print(); +#endif // YOUNG_LIST_VERBOSE + + if (g1_policy()->during_initial_mark_pause()) { + concurrent_mark()->checkpointRootsInitialPre(); + } + +#if YOUNG_LIST_VERBOSE + gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:"); + _young_list->print(); + g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); +#endif // YOUNG_LIST_VERBOSE + + g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info); + + register_humongous_regions_with_cset(); + + assert(check_cset_fast_test(), "Inconsistency in the InCSetState table."); + + _cm->note_start_of_gc(); + // We call this after finalize_cset() to + // ensure that the CSet has been finalized. + _cm->verify_no_cset_oops(); + + if (_hr_printer.is_active()) { + HeapRegion* hr = g1_policy()->collection_set(); + while (hr != NULL) { + _hr_printer.cset(hr); + hr = hr->next_in_collection_set(); + } + } + +#ifdef ASSERT + VerifyCSetClosure cl; + collection_set_iterate(&cl); +#endif // ASSERT + + setup_surviving_young_words(); + + // Initialize the GC alloc regions. + _allocator->init_gc_alloc_regions(evacuation_info); + + // Actually do the work... + evacuate_collection_set(evacuation_info); + + free_collection_set(g1_policy()->collection_set(), evacuation_info); + + eagerly_reclaim_humongous_regions(); + + g1_policy()->clear_collection_set(); + + cleanup_surviving_young_words(); + + // Start a new incremental collection set for the next pause. + g1_policy()->start_incremental_cset_building(); + + clear_cset_fast_test(); + + _young_list->reset_sampled_info(); + + // Don't check the whole heap at this point as the + // GC alloc regions from this pause have been tagged + // as survivors and moved on to the survivor list. + // Survivor regions will fail the !is_young() check. + assert(check_young_list_empty(false /* check_heap */), + "young list should be empty"); + +#if YOUNG_LIST_VERBOSE + gclog_or_tty->print_cr("Before recording survivors.\nYoung List:"); + _young_list->print(); +#endif // YOUNG_LIST_VERBOSE + + g1_policy()->record_survivor_regions(_young_list->survivor_length(), + _young_list->first_survivor_region(), + _young_list->last_survivor_region()); + + _young_list->reset_auxilary_lists(); + + if (evacuation_failed()) { + _allocator->set_used(recalculate_used()); + uint n_queues = MAX2((int)ParallelGCThreads, 1); + for (uint i = 0; i < n_queues; i++) { + if (_evacuation_failed_info_array[i].has_failed()) { + _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); + } + } + } else { + // The "used" of the the collection set have already been subtracted + // when they were freed. Add in the bytes evacuated. + _allocator->increase_used(g1_policy()->bytes_copied_during_gc()); + } + + if (g1_policy()->during_initial_mark_pause()) { + // We have to do this before we notify the CM threads that + // they can start working to make sure that all the + // appropriate initialization is done on the CM object. + concurrent_mark()->checkpointRootsInitialPost(); + set_marking_started(); + // Note that we don't actually trigger the CM thread at + // this point. We do that later when we're sure that + // the current thread has completed its logging output. + } + + allocate_dummy_regions(); + +#if YOUNG_LIST_VERBOSE + gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:"); + _young_list->print(); + g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty); +#endif // YOUNG_LIST_VERBOSE + + _allocator->init_mutator_alloc_region(); + + { + size_t expand_bytes = g1_policy()->expansion_amount(); + if (expand_bytes > 0) { + size_t bytes_before = capacity(); + // No need for an ergo verbose message here, + // expansion_amount() does this when it returns a value > 0. + if (!expand(expand_bytes)) { + // We failed to expand the heap. Cannot do anything about it. + } + } + } + + // We redo the verification but now wrt to the new CSet which + // has just got initialized after the previous CSet was freed. + _cm->verify_no_cset_oops(); + _cm->note_end_of_gc(); + + // This timing is only used by the ergonomics to handle our pause target. + // It is unclear why this should not include the full pause. We will + // investigate this in CR 7178365. + double sample_end_time_sec = os::elapsedTime(); + double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; + g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info); + + MemoryService::track_memory_usage(); + + // In prepare_for_verify() below we'll need to scan the deferred + // update buffers to bring the RSets up-to-date if + // G1HRRSFlushLogBuffersOnVerify has been set. While scanning + // the update buffers we'll probably need to scan cards on the + // regions we just allocated to (i.e., the GC alloc + // regions). However, during the last GC we called + // set_saved_mark() on all the GC alloc regions, so card + // scanning might skip the [saved_mark_word()...top()] area of + // those regions (i.e., the area we allocated objects into + // during the last GC). But it shouldn't. Given that + // saved_mark_word() is conditional on whether the GC time stamp + // on the region is current or not, by incrementing the GC time + // stamp here we invalidate all the GC time stamps on all the + // regions and saved_mark_word() will simply return top() for + // all the regions. This is a nicer way of ensuring this rather + // than iterating over the regions and fixing them. In fact, the + // GC time stamp increment here also ensures that + // saved_mark_word() will return top() between pauses, i.e., + // during concurrent refinement. So we don't need the + // is_gc_active() check to decided which top to use when + // scanning cards (see CR 7039627). + increment_gc_time_stamp(); + + verify_after_gc(); + check_bitmaps("GC End"); + + assert(!ref_processor_stw()->discovery_enabled(), "Postcondition"); + ref_processor_stw()->verify_no_references_recorded(); + + // CM reference discovery will be re-enabled if necessary. + } + + // We should do this after we potentially expand the heap so + // that all the COMMIT events are generated before the end GC + // event, and after we retire the GC alloc regions so that all + // RETIRE events are generated before the end GC event. + _hr_printer.end_gc(false /* full */, (size_t) total_collections()); + +#ifdef TRACESPINNING + ParallelTaskTerminator::print_termination_counts(); +#endif + + gc_epilogue(false); + } + + // Print the remainder of the GC log output. + log_gc_footer(os::elapsedTime() - pause_start_sec); + + // It is not yet to safe to tell the concurrent mark to + // start as we have some optional output below. We don't want the + // output from the concurrent mark thread interfering with this + // logging output either. + + _hrm.verify_optional(); + verify_region_sets_optional(); + + TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats()); + TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); + + print_heap_after_gc(); + trace_heap_after_gc(_gc_tracer_stw); + + // We must call G1MonitoringSupport::update_sizes() in the same scoping level + // as an active TraceMemoryManagerStats object (i.e. before the destructor for the + // TraceMemoryManagerStats is called) so that the G1 memory pools are updated + // before any GC notifications are raised. + g1mm()->update_sizes(); + + _gc_tracer_stw->report_evacuation_info(&evacuation_info); + _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); + _gc_timer_stw->register_gc_end(); + _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); + } + // It should now be safe to tell the concurrent mark thread to start + // without its logging output interfering with the logging output + // that came from the pause. + + if (should_start_conc_mark) { + // CAUTION: after the doConcurrentMark() call below, + // the concurrent marking thread(s) could be running + // concurrently with us. Make sure that anything after + // this point does not assume that we are the only GC thread + // running. Note: of course, the actual marking work will + // not start until the safepoint itself is released in + // SuspendibleThreadSet::desynchronize(). + doConcurrentMark(); + } + + return true; +} + +void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) { + _drain_in_progress = false; + set_evac_failure_closure(cl); + _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray(40, true); +} + +void G1CollectedHeap::finalize_for_evac_failure() { + assert(_evac_failure_scan_stack != NULL && + _evac_failure_scan_stack->length() == 0, + "Postcondition"); + assert(!_drain_in_progress, "Postcondition"); + delete _evac_failure_scan_stack; + _evac_failure_scan_stack = NULL; +} + +void G1CollectedHeap::remove_self_forwarding_pointers() { + double remove_self_forwards_start = os::elapsedTime(); + + set_par_threads(); + G1ParRemoveSelfForwardPtrsTask rsfp_task(this); + workers()->run_task(&rsfp_task); + set_par_threads(0); + + // Now restore saved marks, if any. + assert(_objs_with_preserved_marks.size() == + _preserved_marks_of_objs.size(), "Both or none."); + while (!_objs_with_preserved_marks.is_empty()) { + oop obj = _objs_with_preserved_marks.pop(); + markOop m = _preserved_marks_of_objs.pop(); + obj->set_mark(m); + } + _objs_with_preserved_marks.clear(true); + _preserved_marks_of_objs.clear(true); + + g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); +} + +void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) { + _evac_failure_scan_stack->push(obj); +} + +void G1CollectedHeap::drain_evac_failure_scan_stack() { + assert(_evac_failure_scan_stack != NULL, "precondition"); + + while (_evac_failure_scan_stack->length() > 0) { + oop obj = _evac_failure_scan_stack->pop(); + _evac_failure_closure->set_region(heap_region_containing(obj)); + obj->oop_iterate_backwards(_evac_failure_closure); + } +} + +oop +G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, + oop old) { + assert(obj_in_cs(old), + err_msg("obj: "PTR_FORMAT" should still be in the CSet", + p2i(old))); + markOop m = old->mark(); + oop forward_ptr = old->forward_to_atomic(old); + if (forward_ptr == NULL) { + // Forward-to-self succeeded. + assert(_par_scan_state != NULL, "par scan state"); + OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure(); + uint queue_num = _par_scan_state->queue_num(); + + _evacuation_failed = true; + _evacuation_failed_info_array[queue_num].register_copy_failure(old->size()); + if (_evac_failure_closure != cl) { + MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag); + assert(!_drain_in_progress, + "Should only be true while someone holds the lock."); + // Set the global evac-failure closure to the current thread's. + assert(_evac_failure_closure == NULL, "Or locking has failed."); + set_evac_failure_closure(cl); + // Now do the common part. + handle_evacuation_failure_common(old, m); + // Reset to NULL. + set_evac_failure_closure(NULL); + } else { + // The lock is already held, and this is recursive. + assert(_drain_in_progress, "This should only be the recursive case."); + handle_evacuation_failure_common(old, m); + } + return old; + } else { + // Forward-to-self failed. Either someone else managed to allocate + // space for this object (old != forward_ptr) or they beat us in + // self-forwarding it (old == forward_ptr). + assert(old == forward_ptr || !obj_in_cs(forward_ptr), + err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" " + "should not be in the CSet", + p2i(old), p2i(forward_ptr))); + return forward_ptr; + } +} + +void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) { + preserve_mark_if_necessary(old, m); + + HeapRegion* r = heap_region_containing(old); + if (!r->evacuation_failed()) { + r->set_evacuation_failed(true); + _hr_printer.evac_failure(r); + } + + push_on_evac_failure_scan_stack(old); + + if (!_drain_in_progress) { + // prevent recursion in copy_to_survivor_space() + _drain_in_progress = true; + drain_evac_failure_scan_stack(); + _drain_in_progress = false; + } +} + +void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) { + assert(evacuation_failed(), "Oversaving!"); + // We want to call the "for_promotion_failure" version only in the + // case of a promotion failure. + if (m->must_be_preserved_for_promotion_failure(obj)) { + _objs_with_preserved_marks.push(obj); + _preserved_marks_of_objs.push(m); + } +} + +void G1ParCopyHelper::mark_object(oop obj) { + assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet"); + + // We know that the object is not moving so it's safe to read its size. + _cm->grayRoot(obj, (size_t) obj->size(), _worker_id); +} + +void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) { + assert(from_obj->is_forwarded(), "from obj should be forwarded"); + assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee"); + assert(from_obj != to_obj, "should not be self-forwarded"); + + assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet"); + assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet"); + + // The object might be in the process of being copied by another + // worker so we cannot trust that its to-space image is + // well-formed. So we have to read its size from its from-space + // image which we know should not be changing. + _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id); +} + +template +void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) { + if (_g1->heap_region_containing_raw(new_obj)->is_young()) { + _scanned_klass->record_modified_oops(); + } +} + +template +template +void G1ParCopyClosure::do_oop_work(T* p) { + T heap_oop = oopDesc::load_heap_oop(p); + + if (oopDesc::is_null(heap_oop)) { + return; + } + + oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); + + assert(_worker_id == _par_scan_state->queue_num(), "sanity"); + + const InCSetState state = _g1->in_cset_state(obj); + if (state.is_in_cset()) { + oop forwardee; + markOop m = obj->mark(); + if (m->is_marked()) { + forwardee = (oop) m->decode_pointer(); + } else { + forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m); + } + assert(forwardee != NULL, "forwardee should not be NULL"); + oopDesc::encode_store_heap_oop(p, forwardee); + if (do_mark_object != G1MarkNone && forwardee != obj) { + // If the object is self-forwarded we don't need to explicitly + // mark it, the evacuation failure protocol will do so. + mark_forwarded_object(obj, forwardee); + } + + if (barrier == G1BarrierKlass) { + do_klass_barrier(p, forwardee); + } + } else { + if (state.is_humongous()) { + _g1->set_humongous_is_live(obj); + } + // The object is not in collection set. If we're a root scanning + // closure during an initial mark pause then attempt to mark the object. + if (do_mark_object == G1MarkFromRoot) { + mark_object(obj); + } + } + + if (barrier == G1BarrierEvac) { + _par_scan_state->update_rs(_from, p, _worker_id); + } +} + +template void G1ParCopyClosure::do_oop_work(oop* p); +template void G1ParCopyClosure::do_oop_work(narrowOop* p); + +class G1ParEvacuateFollowersClosure : public VoidClosure { +protected: + G1CollectedHeap* _g1h; + G1ParScanThreadState* _par_scan_state; + RefToScanQueueSet* _queues; + ParallelTaskTerminator* _terminator; + + G1ParScanThreadState* par_scan_state() { return _par_scan_state; } + RefToScanQueueSet* queues() { return _queues; } + ParallelTaskTerminator* terminator() { return _terminator; } + +public: + G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, + G1ParScanThreadState* par_scan_state, + RefToScanQueueSet* queues, + ParallelTaskTerminator* terminator) + : _g1h(g1h), _par_scan_state(par_scan_state), + _queues(queues), _terminator(terminator) {} + + void do_void(); + +private: + inline bool offer_termination(); +}; + +bool G1ParEvacuateFollowersClosure::offer_termination() { + G1ParScanThreadState* const pss = par_scan_state(); + pss->start_term_time(); + const bool res = terminator()->offer_termination(); + pss->end_term_time(); + return res; +} + +void G1ParEvacuateFollowersClosure::do_void() { + G1ParScanThreadState* const pss = par_scan_state(); + pss->trim_queue(); + do { + pss->steal_and_trim_queue(queues()); + } while (!offer_termination()); +} + +class G1KlassScanClosure : public KlassClosure { + G1ParCopyHelper* _closure; + bool _process_only_dirty; + int _count; + public: + G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty) + : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {} + void do_klass(Klass* klass) { + // If the klass has not been dirtied we know that there's + // no references into the young gen and we can skip it. + if (!_process_only_dirty || klass->has_modified_oops()) { + // Clean the klass since we're going to scavenge all the metadata. + klass->clear_modified_oops(); + + // Tell the closure that this klass is the Klass to scavenge + // and is the one to dirty if oops are left pointing into the young gen. + _closure->set_scanned_klass(klass); + + klass->oops_do(_closure); + + _closure->set_scanned_klass(NULL); + } + _count++; + } +}; + +class G1ParTask : public AbstractGangTask { +protected: + G1CollectedHeap* _g1h; + RefToScanQueueSet *_queues; + G1RootProcessor* _root_processor; + ParallelTaskTerminator _terminator; + uint _n_workers; + + Mutex _stats_lock; + Mutex* stats_lock() { return &_stats_lock; } + +public: + G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor) + : AbstractGangTask("G1 collection"), + _g1h(g1h), + _queues(task_queues), + _root_processor(root_processor), + _terminator(0, _queues), + _stats_lock(Mutex::leaf, "parallel G1 stats lock", true) + {} + + RefToScanQueueSet* queues() { return _queues; } + + RefToScanQueue *work_queue(int i) { + return queues()->queue(i); + } + + ParallelTaskTerminator* terminator() { return &_terminator; } + + virtual void set_for_termination(uint active_workers) { + _root_processor->set_num_workers(active_workers); + terminator()->reset_for_reuse(active_workers); + _n_workers = active_workers; + } + + // Helps out with CLD processing. + // + // During InitialMark we need to: + // 1) Scavenge all CLDs for the young GC. + // 2) Mark all objects directly reachable from strong CLDs. + template + class G1CLDClosure : public CLDClosure { + G1ParCopyClosure* _oop_closure; + G1ParCopyClosure _oop_in_klass_closure; + G1KlassScanClosure _klass_in_cld_closure; + bool _claim; + + public: + G1CLDClosure(G1ParCopyClosure* oop_closure, + bool only_young, bool claim) + : _oop_closure(oop_closure), + _oop_in_klass_closure(oop_closure->g1(), + oop_closure->pss(), + oop_closure->rp()), + _klass_in_cld_closure(&_oop_in_klass_closure, only_young), + _claim(claim) { + + } + + void do_cld(ClassLoaderData* cld) { + cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim); + } + }; + + void work(uint worker_id) { + if (worker_id >= _n_workers) return; // no work needed this round + + _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime()); + + { + ResourceMark rm; + HandleMark hm; + + ReferenceProcessor* rp = _g1h->ref_processor_stw(); + + G1ParScanThreadState pss(_g1h, worker_id, rp); + G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp); + + pss.set_evac_failure_closure(&evac_failure_cl); + + bool only_young = _g1h->g1_policy()->gcs_are_young(); + + // Non-IM young GC. + G1ParCopyClosure scan_only_root_cl(_g1h, &pss, rp); + G1CLDClosure scan_only_cld_cl(&scan_only_root_cl, + only_young, // Only process dirty klasses. + false); // No need to claim CLDs. + // IM young GC. + // Strong roots closures. + G1ParCopyClosure scan_mark_root_cl(_g1h, &pss, rp); + G1CLDClosure scan_mark_cld_cl(&scan_mark_root_cl, + false, // Process all klasses. + true); // Need to claim CLDs. + // Weak roots closures. + G1ParCopyClosure scan_mark_weak_root_cl(_g1h, &pss, rp); + G1CLDClosure scan_mark_weak_cld_cl(&scan_mark_weak_root_cl, + false, // Process all klasses. + true); // Need to claim CLDs. + + OopClosure* strong_root_cl; + OopClosure* weak_root_cl; + CLDClosure* strong_cld_cl; + CLDClosure* weak_cld_cl; + + bool trace_metadata = false; + + if (_g1h->g1_policy()->during_initial_mark_pause()) { + // We also need to mark copied objects. + strong_root_cl = &scan_mark_root_cl; + strong_cld_cl = &scan_mark_cld_cl; + if (ClassUnloadingWithConcurrentMark) { + weak_root_cl = &scan_mark_weak_root_cl; + weak_cld_cl = &scan_mark_weak_cld_cl; + trace_metadata = true; + } else { + weak_root_cl = &scan_mark_root_cl; + weak_cld_cl = &scan_mark_cld_cl; + } + } else { + strong_root_cl = &scan_only_root_cl; + weak_root_cl = &scan_only_root_cl; + strong_cld_cl = &scan_only_cld_cl; + weak_cld_cl = &scan_only_cld_cl; + } + + pss.start_strong_roots(); + + _root_processor->evacuate_roots(strong_root_cl, + weak_root_cl, + strong_cld_cl, + weak_cld_cl, + trace_metadata, + worker_id); + + G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss); + _root_processor->scan_remembered_sets(&push_heap_rs_cl, + weak_root_cl, + worker_id); + pss.end_strong_roots(); + + { + double start = os::elapsedTime(); + G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator); + evac.do_void(); + double elapsed_sec = os::elapsedTime() - start; + double term_sec = pss.term_time(); + _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); + _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); + _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts()); + } + _g1h->g1_policy()->record_thread_age_table(pss.age_table()); + _g1h->update_surviving_young_words(pss.surviving_young_words()+1); + + if (PrintTerminationStats) { + MutexLocker x(stats_lock()); + pss.print_termination_stats(worker_id); + } + + assert(pss.queue_is_empty(), "should be empty"); + + // Close the inner scope so that the ResourceMark and HandleMark + // destructors are executed here and are included as part of the + // "GC Worker Time". + } + _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); + } +}; + +class G1StringSymbolTableUnlinkTask : public AbstractGangTask { +private: + BoolObjectClosure* _is_alive; + int _initial_string_table_size; + int _initial_symbol_table_size; + + bool _process_strings; + int _strings_processed; + int _strings_removed; + + bool _process_symbols; + int _symbols_processed; + int _symbols_removed; + +public: + G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) : + AbstractGangTask("String/Symbol Unlinking"), + _is_alive(is_alive), + _process_strings(process_strings), _strings_processed(0), _strings_removed(0), + _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) { + + _initial_string_table_size = StringTable::the_table()->table_size(); + _initial_symbol_table_size = SymbolTable::the_table()->table_size(); + if (process_strings) { + StringTable::clear_parallel_claimed_index(); + } + if (process_symbols) { + SymbolTable::clear_parallel_claimed_index(); + } + } + + ~G1StringSymbolTableUnlinkTask() { + guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, + err_msg("claim value %d after unlink less than initial string table size %d", + StringTable::parallel_claimed_index(), _initial_string_table_size)); + guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, + err_msg("claim value %d after unlink less than initial symbol table size %d", + SymbolTable::parallel_claimed_index(), _initial_symbol_table_size)); + + if (G1TraceStringSymbolTableScrubbing) { + gclog_or_tty->print_cr("Cleaned string and symbol table, " + "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, " + "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed", + strings_processed(), strings_removed(), + symbols_processed(), symbols_removed()); + } + } + + void work(uint worker_id) { + int strings_processed = 0; + int strings_removed = 0; + int symbols_processed = 0; + int symbols_removed = 0; + if (_process_strings) { + StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); + Atomic::add(strings_processed, &_strings_processed); + Atomic::add(strings_removed, &_strings_removed); + } + if (_process_symbols) { + SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); + Atomic::add(symbols_processed, &_symbols_processed); + Atomic::add(symbols_removed, &_symbols_removed); + } + } + + size_t strings_processed() const { return (size_t)_strings_processed; } + size_t strings_removed() const { return (size_t)_strings_removed; } + + size_t symbols_processed() const { return (size_t)_symbols_processed; } + size_t symbols_removed() const { return (size_t)_symbols_removed; } +}; + +class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC { +private: + static Monitor* _lock; + + BoolObjectClosure* const _is_alive; + const bool _unloading_occurred; + const uint _num_workers; + + // Variables used to claim nmethods. + nmethod* _first_nmethod; + volatile nmethod* _claimed_nmethod; + + // The list of nmethods that need to be processed by the second pass. + volatile nmethod* _postponed_list; + volatile uint _num_entered_barrier; + + public: + G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : + _is_alive(is_alive), + _unloading_occurred(unloading_occurred), + _num_workers(num_workers), + _first_nmethod(NULL), + _claimed_nmethod(NULL), + _postponed_list(NULL), + _num_entered_barrier(0) + { + nmethod::increase_unloading_clock(); + // Get first alive nmethod + NMethodIterator iter = NMethodIterator(); + if(iter.next_alive()) { + _first_nmethod = iter.method(); + } + _claimed_nmethod = (volatile nmethod*)_first_nmethod; + } + + ~G1CodeCacheUnloadingTask() { + CodeCache::verify_clean_inline_caches(); + + CodeCache::set_needs_cache_clean(false); + guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); + + CodeCache::verify_icholder_relocations(); + } + + private: + void add_to_postponed_list(nmethod* nm) { + nmethod* old; + do { + old = (nmethod*)_postponed_list; + nm->set_unloading_next(old); + } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); + } + + void clean_nmethod(nmethod* nm) { + bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); + + if (postponed) { + // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. + add_to_postponed_list(nm); + } + + // Mark that this thread has been cleaned/unloaded. + // After this call, it will be safe to ask if this nmethod was unloaded or not. + nm->set_unloading_clock(nmethod::global_unloading_clock()); + } + + void clean_nmethod_postponed(nmethod* nm) { + nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); + } + + static const int MaxClaimNmethods = 16; + + void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) { + nmethod* first; + NMethodIterator last; + + do { + *num_claimed_nmethods = 0; + + first = (nmethod*)_claimed_nmethod; + last = NMethodIterator(first); + + if (first != NULL) { + + for (int i = 0; i < MaxClaimNmethods; i++) { + if (!last.next_alive()) { + break; + } + claimed_nmethods[i] = last.method(); + (*num_claimed_nmethods)++; + } + } + + } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); + } + + nmethod* claim_postponed_nmethod() { + nmethod* claim; + nmethod* next; + + do { + claim = (nmethod*)_postponed_list; + if (claim == NULL) { + return NULL; + } + + next = claim->unloading_next(); + + } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim); + + return claim; + } + + public: + // Mark that we're done with the first pass of nmethod cleaning. + void barrier_mark(uint worker_id) { + MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); + _num_entered_barrier++; + if (_num_entered_barrier == _num_workers) { + ml.notify_all(); + } + } + + // See if we have to wait for the other workers to + // finish their first-pass nmethod cleaning work. + void barrier_wait(uint worker_id) { + if (_num_entered_barrier < _num_workers) { + MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); + while (_num_entered_barrier < _num_workers) { + ml.wait(Mutex::_no_safepoint_check_flag, 0, false); + } + } + } + + // Cleaning and unloading of nmethods. Some work has to be postponed + // to the second pass, when we know which nmethods survive. + void work_first_pass(uint worker_id) { + // The first nmethods is claimed by the first worker. + if (worker_id == 0 && _first_nmethod != NULL) { + clean_nmethod(_first_nmethod); + _first_nmethod = NULL; + } + + int num_claimed_nmethods; + nmethod* claimed_nmethods[MaxClaimNmethods]; + + while (true) { + claim_nmethods(claimed_nmethods, &num_claimed_nmethods); + + if (num_claimed_nmethods == 0) { + break; + } + + for (int i = 0; i < num_claimed_nmethods; i++) { + clean_nmethod(claimed_nmethods[i]); + } + } + } + + void work_second_pass(uint worker_id) { + nmethod* nm; + // Take care of postponed nmethods. + while ((nm = claim_postponed_nmethod()) != NULL) { + clean_nmethod_postponed(nm); + } + } +}; + +Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); + +class G1KlassCleaningTask : public StackObj { + BoolObjectClosure* _is_alive; + volatile jint _clean_klass_tree_claimed; + ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; + + public: + G1KlassCleaningTask(BoolObjectClosure* is_alive) : + _is_alive(is_alive), + _clean_klass_tree_claimed(0), + _klass_iterator() { + } + + private: + bool claim_clean_klass_tree_task() { + if (_clean_klass_tree_claimed) { + return false; + } + + return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0; + } + + InstanceKlass* claim_next_klass() { + Klass* klass; + do { + klass =_klass_iterator.next_klass(); + } while (klass != NULL && !klass->oop_is_instance()); + + return (InstanceKlass*)klass; + } + +public: + + void clean_klass(InstanceKlass* ik) { + ik->clean_implementors_list(_is_alive); + ik->clean_method_data(_is_alive); + + // G1 specific cleanup work that has + // been moved here to be done in parallel. + ik->clean_dependent_nmethods(); + } + + void work() { + ResourceMark rm; + + // One worker will clean the subklass/sibling klass tree. + if (claim_clean_klass_tree_task()) { + Klass::clean_subklass_tree(_is_alive); + } + + // All workers will help cleaning the classes, + InstanceKlass* klass; + while ((klass = claim_next_klass()) != NULL) { + clean_klass(klass); + } + } +}; + +// To minimize the remark pause times, the tasks below are done in parallel. +class G1ParallelCleaningTask : public AbstractGangTask { +private: + G1StringSymbolTableUnlinkTask _string_symbol_task; + G1CodeCacheUnloadingTask _code_cache_task; + G1KlassCleaningTask _klass_cleaning_task; + +public: + // The constructor is run in the VMThread. + G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) : + AbstractGangTask("Parallel Cleaning"), + _string_symbol_task(is_alive, process_strings, process_symbols), + _code_cache_task(num_workers, is_alive, unloading_occurred), + _klass_cleaning_task(is_alive) { + } + + // The parallel work done by all worker threads. + void work(uint worker_id) { + // Do first pass of code cache cleaning. + _code_cache_task.work_first_pass(worker_id); + + // Let the threads mark that the first pass is done. + _code_cache_task.barrier_mark(worker_id); + + // Clean the Strings and Symbols. + _string_symbol_task.work(worker_id); + + // Wait for all workers to finish the first code cache cleaning pass. + _code_cache_task.barrier_wait(worker_id); + + // Do the second code cache cleaning work, which realize on + // the liveness information gathered during the first pass. + _code_cache_task.work_second_pass(worker_id); + + // Clean all klasses that were not unloaded. + _klass_cleaning_task.work(); + } +}; + + +void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive, + bool process_strings, + bool process_symbols, + bool class_unloading_occurred) { + uint n_workers = workers()->active_workers(); + + G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, + n_workers, class_unloading_occurred); + set_par_threads(n_workers); + workers()->run_task(&g1_unlink_task); + set_par_threads(0); +} + +void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive, + bool process_strings, bool process_symbols) { + { + uint n_workers = workers()->active_workers(); + G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols); + set_par_threads(n_workers); + workers()->run_task(&g1_unlink_task); + set_par_threads(0); + } + + if (G1StringDedup::is_enabled()) { + G1StringDedup::unlink(is_alive); + } +} + +class G1RedirtyLoggedCardsTask : public AbstractGangTask { + private: + DirtyCardQueueSet* _queue; + public: + G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { } + + virtual void work(uint worker_id) { + G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times(); + G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); + + RedirtyLoggedCardTableEntryClosure cl; + _queue->par_apply_closure_to_all_completed_buffers(&cl); + + phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed()); + } +}; + +void G1CollectedHeap::redirty_logged_cards() { + double redirty_logged_cards_start = os::elapsedTime(); + + uint n_workers = workers()->active_workers(); + + G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set()); + dirty_card_queue_set().reset_for_par_iteration(); + set_par_threads(n_workers); + workers()->run_task(&redirty_task); + set_par_threads(0); + + DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set(); + dcq.merge_bufferlists(&dirty_card_queue_set()); + assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); + + g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); +} + +// Weak Reference Processing support + +// An always "is_alive" closure that is used to preserve referents. +// If the object is non-null then it's alive. Used in the preservation +// of referent objects that are pointed to by reference objects +// discovered by the CM ref processor. +class G1AlwaysAliveClosure: public BoolObjectClosure { + G1CollectedHeap* _g1; +public: + G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} + bool do_object_b(oop p) { + if (p != NULL) { + return true; + } + return false; + } +}; + +bool G1STWIsAliveClosure::do_object_b(oop p) { + // An object is reachable if it is outside the collection set, + // or is inside and copied. + return !_g1->obj_in_cs(p) || p->is_forwarded(); +} + +// Non Copying Keep Alive closure +class G1KeepAliveClosure: public OopClosure { + G1CollectedHeap* _g1; +public: + G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} + void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } + void do_oop(oop* p) { + oop obj = *p; + assert(obj != NULL, "the caller should have filtered out NULL values"); + + const InCSetState cset_state = _g1->in_cset_state(obj); + if (!cset_state.is_in_cset_or_humongous()) { + return; + } + if (cset_state.is_in_cset()) { + assert( obj->is_forwarded(), "invariant" ); + *p = obj->forwardee(); + } else { + assert(!obj->is_forwarded(), "invariant" ); + assert(cset_state.is_humongous(), + err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value())); + _g1->set_humongous_is_live(obj); + } + } +}; + +// Copying Keep Alive closure - can be called from both +// serial and parallel code as long as different worker +// threads utilize different G1ParScanThreadState instances +// and different queues. + +class G1CopyingKeepAliveClosure: public OopClosure { + G1CollectedHeap* _g1h; + OopClosure* _copy_non_heap_obj_cl; + G1ParScanThreadState* _par_scan_state; + +public: + G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, + OopClosure* non_heap_obj_cl, + G1ParScanThreadState* pss): + _g1h(g1h), + _copy_non_heap_obj_cl(non_heap_obj_cl), + _par_scan_state(pss) + {} + + virtual void do_oop(narrowOop* p) { do_oop_work(p); } + virtual void do_oop( oop* p) { do_oop_work(p); } + + template void do_oop_work(T* p) { + oop obj = oopDesc::load_decode_heap_oop(p); + + if (_g1h->is_in_cset_or_humongous(obj)) { + // If the referent object has been forwarded (either copied + // to a new location or to itself in the event of an + // evacuation failure) then we need to update the reference + // field and, if both reference and referent are in the G1 + // heap, update the RSet for the referent. + // + // If the referent has not been forwarded then we have to keep + // it alive by policy. Therefore we have copy the referent. + // + // If the reference field is in the G1 heap then we can push + // on the PSS queue. When the queue is drained (after each + // phase of reference processing) the object and it's followers + // will be copied, the reference field set to point to the + // new location, and the RSet updated. Otherwise we need to + // use the the non-heap or metadata closures directly to copy + // the referent object and update the pointer, while avoiding + // updating the RSet. + + if (_g1h->is_in_g1_reserved(p)) { + _par_scan_state->push_on_queue(p); + } else { + assert(!Metaspace::contains((const void*)p), + err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p))); + _copy_non_heap_obj_cl->do_oop(p); + } + } + } +}; + +// Serial drain queue closure. Called as the 'complete_gc' +// closure for each discovered list in some of the +// reference processing phases. + +class G1STWDrainQueueClosure: public VoidClosure { +protected: + G1CollectedHeap* _g1h; + G1ParScanThreadState* _par_scan_state; + + G1ParScanThreadState* par_scan_state() { return _par_scan_state; } + +public: + G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : + _g1h(g1h), + _par_scan_state(pss) + { } + + void do_void() { + G1ParScanThreadState* const pss = par_scan_state(); + pss->trim_queue(); + } +}; + +// Parallel Reference Processing closures + +// Implementation of AbstractRefProcTaskExecutor for parallel reference +// processing during G1 evacuation pauses. + +class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { +private: + G1CollectedHeap* _g1h; + RefToScanQueueSet* _queues; + FlexibleWorkGang* _workers; + uint _active_workers; + +public: + G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, + FlexibleWorkGang* workers, + RefToScanQueueSet *task_queues, + uint n_workers) : + _g1h(g1h), + _queues(task_queues), + _workers(workers), + _active_workers(n_workers) + { + assert(n_workers > 0, "shouldn't call this otherwise"); + } + + // Executes the given task using concurrent marking worker threads. + virtual void execute(ProcessTask& task); + virtual void execute(EnqueueTask& task); +}; + +// Gang task for possibly parallel reference processing + +class G1STWRefProcTaskProxy: public AbstractGangTask { + typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; + ProcessTask& _proc_task; + G1CollectedHeap* _g1h; + RefToScanQueueSet *_task_queues; + ParallelTaskTerminator* _terminator; + +public: + G1STWRefProcTaskProxy(ProcessTask& proc_task, + G1CollectedHeap* g1h, + RefToScanQueueSet *task_queues, + ParallelTaskTerminator* terminator) : + AbstractGangTask("Process reference objects in parallel"), + _proc_task(proc_task), + _g1h(g1h), + _task_queues(task_queues), + _terminator(terminator) + {} + + virtual void work(uint worker_id) { + // The reference processing task executed by a single worker. + ResourceMark rm; + HandleMark hm; + + G1STWIsAliveClosure is_alive(_g1h); + + G1ParScanThreadState pss(_g1h, worker_id, NULL); + G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); + + pss.set_evac_failure_closure(&evac_failure_cl); + + G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); + + G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); + + OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; + + if (_g1h->g1_policy()->during_initial_mark_pause()) { + // We also need to mark copied objects. + copy_non_heap_cl = ©_mark_non_heap_cl; + } + + // Keep alive closure. + G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); + + // Complete GC closure + G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator); + + // Call the reference processing task's work routine. + _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); + + // Note we cannot assert that the refs array is empty here as not all + // of the processing tasks (specifically phase2 - pp2_work) execute + // the complete_gc closure (which ordinarily would drain the queue) so + // the queue may not be empty. + } +}; + +// Driver routine for parallel reference processing. +// Creates an instance of the ref processing gang +// task and has the worker threads execute it. +void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { + assert(_workers != NULL, "Need parallel worker threads."); + + ParallelTaskTerminator terminator(_active_workers, _queues); + G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator); + + _g1h->set_par_threads(_active_workers); + _workers->run_task(&proc_task_proxy); + _g1h->set_par_threads(0); +} + +// Gang task for parallel reference enqueueing. + +class G1STWRefEnqueueTaskProxy: public AbstractGangTask { + typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; + EnqueueTask& _enq_task; + +public: + G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : + AbstractGangTask("Enqueue reference objects in parallel"), + _enq_task(enq_task) + { } + + virtual void work(uint worker_id) { + _enq_task.work(worker_id); + } +}; + +// Driver routine for parallel reference enqueueing. +// Creates an instance of the ref enqueueing gang +// task and has the worker threads execute it. + +void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { + assert(_workers != NULL, "Need parallel worker threads."); + + G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); + + _g1h->set_par_threads(_active_workers); + _workers->run_task(&enq_task_proxy); + _g1h->set_par_threads(0); +} + +// End of weak reference support closures + +// Abstract task used to preserve (i.e. copy) any referent objects +// that are in the collection set and are pointed to by reference +// objects discovered by the CM ref processor. + +class G1ParPreserveCMReferentsTask: public AbstractGangTask { +protected: + G1CollectedHeap* _g1h; + RefToScanQueueSet *_queues; + ParallelTaskTerminator _terminator; + uint _n_workers; + +public: + G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) : + AbstractGangTask("ParPreserveCMReferents"), + _g1h(g1h), + _queues(task_queues), + _terminator(workers, _queues), + _n_workers(workers) + { } + + void work(uint worker_id) { + ResourceMark rm; + HandleMark hm; + + G1ParScanThreadState pss(_g1h, worker_id, NULL); + G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL); + + pss.set_evac_failure_closure(&evac_failure_cl); + + assert(pss.queue_is_empty(), "both queue and overflow should be empty"); + + G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL); + + G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL); + + OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; + + if (_g1h->g1_policy()->during_initial_mark_pause()) { + // We also need to mark copied objects. + copy_non_heap_cl = ©_mark_non_heap_cl; + } + + // Is alive closure + G1AlwaysAliveClosure always_alive(_g1h); + + // Copying keep alive closure. Applied to referent objects that need + // to be copied. + G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss); + + ReferenceProcessor* rp = _g1h->ref_processor_cm(); + + uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q(); + uint stride = MIN2(MAX2(_n_workers, 1U), limit); + + // limit is set using max_num_q() - which was set using ParallelGCThreads. + // So this must be true - but assert just in case someone decides to + // change the worker ids. + assert(worker_id < limit, "sanity"); + assert(!rp->discovery_is_atomic(), "check this code"); + + // Select discovered lists [i, i+stride, i+2*stride,...,limit) + for (uint idx = worker_id; idx < limit; idx += stride) { + DiscoveredList& ref_list = rp->discovered_refs()[idx]; + + DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive); + while (iter.has_next()) { + // Since discovery is not atomic for the CM ref processor, we + // can see some null referent objects. + iter.load_ptrs(DEBUG_ONLY(true)); + oop ref = iter.obj(); + + // This will filter nulls. + if (iter.is_referent_alive()) { + iter.make_referent_alive(); + } + iter.move_to_next(); + } + } + + // Drain the queue - which may cause stealing + G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator); + drain_queue.do_void(); + // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure + assert(pss.queue_is_empty(), "should be"); + } +}; + +// Weak Reference processing during an evacuation pause (part 1). +void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) { + double ref_proc_start = os::elapsedTime(); + + ReferenceProcessor* rp = _ref_processor_stw; + assert(rp->discovery_enabled(), "should have been enabled"); + + // Any reference objects, in the collection set, that were 'discovered' + // by the CM ref processor should have already been copied (either by + // applying the external root copy closure to the discovered lists, or + // by following an RSet entry). + // + // But some of the referents, that are in the collection set, that these + // reference objects point to may not have been copied: the STW ref + // processor would have seen that the reference object had already + // been 'discovered' and would have skipped discovering the reference, + // but would not have treated the reference object as a regular oop. + // As a result the copy closure would not have been applied to the + // referent object. + // + // We need to explicitly copy these referent objects - the references + // will be processed at the end of remarking. + // + // We also need to do this copying before we process the reference + // objects discovered by the STW ref processor in case one of these + // referents points to another object which is also referenced by an + // object discovered by the STW ref processor. + + assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers"); + + set_par_threads(no_of_gc_workers); + G1ParPreserveCMReferentsTask keep_cm_referents(this, + no_of_gc_workers, + _task_queues); + + workers()->run_task(&keep_cm_referents); + + set_par_threads(0); + + // Closure to test whether a referent is alive. + G1STWIsAliveClosure is_alive(this); + + // Even when parallel reference processing is enabled, the processing + // of JNI refs is serial and performed serially by the current thread + // rather than by a worker. The following PSS will be used for processing + // JNI refs. + + // Use only a single queue for this PSS. + G1ParScanThreadState pss(this, 0, NULL); + + // We do not embed a reference processor in the copying/scanning + // closures while we're actually processing the discovered + // reference objects. + G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL); + + pss.set_evac_failure_closure(&evac_failure_cl); + + assert(pss.queue_is_empty(), "pre-condition"); + + G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL); + + G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL); + + OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl; + + if (g1_policy()->during_initial_mark_pause()) { + // We also need to mark copied objects. + copy_non_heap_cl = ©_mark_non_heap_cl; + } + + // Keep alive closure. + G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss); + + // Serial Complete GC closure + G1STWDrainQueueClosure drain_queue(this, &pss); + + // Setup the soft refs policy... + rp->setup_policy(false); + + ReferenceProcessorStats stats; + if (!rp->processing_is_mt()) { + // Serial reference processing... + stats = rp->process_discovered_references(&is_alive, + &keep_alive, + &drain_queue, + NULL, + _gc_timer_stw, + _gc_tracer_stw->gc_id()); + } else { + // Parallel reference processing + assert(rp->num_q() == no_of_gc_workers, "sanity"); + assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); + + G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); + stats = rp->process_discovered_references(&is_alive, + &keep_alive, + &drain_queue, + &par_task_executor, + _gc_timer_stw, + _gc_tracer_stw->gc_id()); + } + + _gc_tracer_stw->report_gc_reference_stats(stats); + + // We have completed copying any necessary live referent objects. + assert(pss.queue_is_empty(), "both queue and overflow should be empty"); + + double ref_proc_time = os::elapsedTime() - ref_proc_start; + g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); +} + +// Weak Reference processing during an evacuation pause (part 2). +void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) { + double ref_enq_start = os::elapsedTime(); + + ReferenceProcessor* rp = _ref_processor_stw; + assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); + + // Now enqueue any remaining on the discovered lists on to + // the pending list. + if (!rp->processing_is_mt()) { + // Serial reference processing... + rp->enqueue_discovered_references(); + } else { + // Parallel reference enqueueing + + assert(no_of_gc_workers == workers()->active_workers(), + "Need to reset active workers"); + assert(rp->num_q() == no_of_gc_workers, "sanity"); + assert(no_of_gc_workers <= rp->max_num_q(), "sanity"); + + G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers); + rp->enqueue_discovered_references(&par_task_executor); + } + + rp->verify_no_references_recorded(); + assert(!rp->discovery_enabled(), "should have been disabled"); + + // FIXME + // CM's reference processing also cleans up the string and symbol tables. + // Should we do that here also? We could, but it is a serial operation + // and could significantly increase the pause time. + + double ref_enq_time = os::elapsedTime() - ref_enq_start; + g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); +} + +void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) { + _expand_heap_after_alloc_failure = true; + _evacuation_failed = false; + + // Should G1EvacuationFailureALot be in effect for this GC? + NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) + + g1_rem_set()->prepare_for_oops_into_collection_set_do(); + + // Disable the hot card cache. + G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache(); + hot_card_cache->reset_hot_cache_claimed_index(); + hot_card_cache->set_use_cache(false); + + const uint n_workers = workers()->active_workers(); + assert(UseDynamicNumberOfGCThreads || + n_workers == workers()->total_workers(), + "If not dynamic should be using all the workers"); + set_par_threads(n_workers); + + + init_for_evac_failure(NULL); + + assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); + double start_par_time_sec = os::elapsedTime(); + double end_par_time_sec; + + { + G1RootProcessor root_processor(this); + G1ParTask g1_par_task(this, _task_queues, &root_processor); + // InitialMark needs claim bits to keep track of the marked-through CLDs. + if (g1_policy()->during_initial_mark_pause()) { + ClassLoaderDataGraph::clear_claimed_marks(); + } + + // The individual threads will set their evac-failure closures. + if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr(); + // These tasks use ShareHeap::_process_strong_tasks + assert(UseDynamicNumberOfGCThreads || + workers()->active_workers() == workers()->total_workers(), + "If not dynamic should be using all the workers"); + workers()->run_task(&g1_par_task); + end_par_time_sec = os::elapsedTime(); + + // Closing the inner scope will execute the destructor + // for the G1RootProcessor object. We record the current + // elapsed time before closing the scope so that time + // taken for the destructor is NOT included in the + // reported parallel time. + } + + G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); + + double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; + phase_times->record_par_time(par_time_ms); + + double code_root_fixup_time_ms = + (os::elapsedTime() - end_par_time_sec) * 1000.0; + phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); + + set_par_threads(0); + + // Process any discovered reference objects - we have + // to do this _before_ we retire the GC alloc regions + // as we may have to copy some 'reachable' referent + // objects (and their reachable sub-graphs) that were + // not copied during the pause. + process_discovered_references(n_workers); + + if (G1StringDedup::is_enabled()) { + double fixup_start = os::elapsedTime(); + + G1STWIsAliveClosure is_alive(this); + G1KeepAliveClosure keep_alive(this); + G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times); + + double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; + phase_times->record_string_dedup_fixup_time(fixup_time_ms); + } + + _allocator->release_gc_alloc_regions(n_workers, evacuation_info); + g1_rem_set()->cleanup_after_oops_into_collection_set_do(); + + // Reset and re-enable the hot card cache. + // Note the counts for the cards in the regions in the + // collection set are reset when the collection set is freed. + hot_card_cache->reset_hot_cache(); + hot_card_cache->set_use_cache(true); + + purge_code_root_memory(); + + finalize_for_evac_failure(); + + if (evacuation_failed()) { + remove_self_forwarding_pointers(); + + // Reset the G1EvacuationFailureALot counters and flags + // Note: the values are reset only when an actual + // evacuation failure occurs. + NOT_PRODUCT(reset_evacuation_should_fail();) + } + + // Enqueue any remaining references remaining on the STW + // reference processor's discovered lists. We need to do + // this after the card table is cleaned (and verified) as + // the act of enqueueing entries on to the pending list + // will log these updates (and dirty their associated + // cards). We need these updates logged to update any + // RSets. + enqueue_discovered_references(n_workers); + + redirty_logged_cards(); + COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); +} + +void G1CollectedHeap::free_region(HeapRegion* hr, + FreeRegionList* free_list, + bool par, + bool locked) { + assert(!hr->is_free(), "the region should not be free"); + assert(!hr->is_empty(), "the region should not be empty"); + assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); + assert(free_list != NULL, "pre-condition"); + + if (G1VerifyBitmaps) { + MemRegion mr(hr->bottom(), hr->end()); + concurrent_mark()->clearRangePrevBitmap(mr); + } + + // Clear the card counts for this region. + // Note: we only need to do this if the region is not young + // (since we don't refine cards in young regions). + if (!hr->is_young()) { + _cg1r->hot_card_cache()->reset_card_counts(hr); + } + hr->hr_clear(par, true /* clear_space */, locked /* locked */); + free_list->add_ordered(hr); +} + +void G1CollectedHeap::free_humongous_region(HeapRegion* hr, + FreeRegionList* free_list, + bool par) { + assert(hr->is_starts_humongous(), "this is only for starts humongous regions"); + assert(free_list != NULL, "pre-condition"); + + size_t hr_capacity = hr->capacity(); + // We need to read this before we make the region non-humongous, + // otherwise the information will be gone. + uint last_index = hr->last_hc_index(); + hr->clear_humongous(); + free_region(hr, free_list, par); + + uint i = hr->hrm_index() + 1; + while (i < last_index) { + HeapRegion* curr_hr = region_at(i); + assert(curr_hr->is_continues_humongous(), "invariant"); + curr_hr->clear_humongous(); + free_region(curr_hr, free_list, par); + i += 1; + } +} + +void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, + const HeapRegionSetCount& humongous_regions_removed) { + if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) { + MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); + _old_set.bulk_remove(old_regions_removed); + _humongous_set.bulk_remove(humongous_regions_removed); + } + +} + +void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { + assert(list != NULL, "list can't be null"); + if (!list->is_empty()) { + MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); + _hrm.insert_list_into_free_list(list); + } +} + +void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { + _allocator->decrease_used(bytes); +} + +class G1ParCleanupCTTask : public AbstractGangTask { + G1SATBCardTableModRefBS* _ct_bs; + G1CollectedHeap* _g1h; + HeapRegion* volatile _su_head; +public: + G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs, + G1CollectedHeap* g1h) : + AbstractGangTask("G1 Par Cleanup CT Task"), + _ct_bs(ct_bs), _g1h(g1h) { } + + void work(uint worker_id) { + HeapRegion* r; + while (r = _g1h->pop_dirty_cards_region()) { + clear_cards(r); + } + } + + void clear_cards(HeapRegion* r) { + // Cards of the survivors should have already been dirtied. + if (!r->is_survivor()) { + _ct_bs->clear(MemRegion(r->bottom(), r->end())); + } + } +}; + +#ifndef PRODUCT +class G1VerifyCardTableCleanup: public HeapRegionClosure { + G1CollectedHeap* _g1h; + G1SATBCardTableModRefBS* _ct_bs; +public: + G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs) + : _g1h(g1h), _ct_bs(ct_bs) { } + virtual bool doHeapRegion(HeapRegion* r) { + if (r->is_survivor()) { + _g1h->verify_dirty_region(r); + } else { + _g1h->verify_not_dirty_region(r); + } + return false; + } +}; + +void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) { + // All of the region should be clean. + G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); + MemRegion mr(hr->bottom(), hr->end()); + ct_bs->verify_not_dirty_region(mr); +} + +void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) { + // We cannot guarantee that [bottom(),end()] is dirty. Threads + // dirty allocated blocks as they allocate them. The thread that + // retires each region and replaces it with a new one will do a + // maximal allocation to fill in [pre_dummy_top(),end()] but will + // not dirty that area (one less thing to have to do while holding + // a lock). So we can only verify that [bottom(),pre_dummy_top()] + // is dirty. + G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); + MemRegion mr(hr->bottom(), hr->pre_dummy_top()); + if (hr->is_young()) { + ct_bs->verify_g1_young_region(mr); + } else { + ct_bs->verify_dirty_region(mr); + } +} + +void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) { + G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); + for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) { + verify_dirty_region(hr); + } +} + +void G1CollectedHeap::verify_dirty_young_regions() { + verify_dirty_young_list(_young_list->first_region()); +} + +bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, + HeapWord* tams, HeapWord* end) { + guarantee(tams <= end, + err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end))); + HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end); + if (result < end) { + gclog_or_tty->cr(); + gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT, + bitmap_name, p2i(result)); + gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT, + bitmap_name, p2i(tams), p2i(end)); + return false; + } + return true; +} + +bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) { + CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap(); + CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap(); + + HeapWord* bottom = hr->bottom(); + HeapWord* ptams = hr->prev_top_at_mark_start(); + HeapWord* ntams = hr->next_top_at_mark_start(); + HeapWord* end = hr->end(); + + bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end); + + bool res_n = true; + // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window + // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap + // if we happen to be in that state. + if (mark_in_progress() || !_cmThread->in_progress()) { + res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end); + } + if (!res_p || !res_n) { + gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT, + HR_FORMAT_PARAMS(hr)); + gclog_or_tty->print_cr("#### Caller: %s", caller); + return false; + } + return true; +} + +void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) { + if (!G1VerifyBitmaps) return; + + guarantee(verify_bitmaps(caller, hr), "bitmap verification"); +} + +class G1VerifyBitmapClosure : public HeapRegionClosure { +private: + const char* _caller; + G1CollectedHeap* _g1h; + bool _failures; + +public: + G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) : + _caller(caller), _g1h(g1h), _failures(false) { } + + bool failures() { return _failures; } + + virtual bool doHeapRegion(HeapRegion* hr) { + if (hr->is_continues_humongous()) return false; + + bool result = _g1h->verify_bitmaps(_caller, hr); + if (!result) { + _failures = true; + } + return false; + } +}; + +void G1CollectedHeap::check_bitmaps(const char* caller) { + if (!G1VerifyBitmaps) return; + + G1VerifyBitmapClosure cl(caller, this); + heap_region_iterate(&cl); + guarantee(!cl.failures(), "bitmap verification"); +} + +class G1CheckCSetFastTableClosure : public HeapRegionClosure { + private: + bool _failures; + public: + G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { } + + virtual bool doHeapRegion(HeapRegion* hr) { + uint i = hr->hrm_index(); + InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i); + if (hr->is_humongous()) { + if (hr->in_collection_set()) { + gclog_or_tty->print_cr("\n## humongous region %u in CSet", i); + _failures = true; + return true; + } + if (cset_state.is_in_cset()) { + gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i); + _failures = true; + return true; + } + if (hr->is_continues_humongous() && cset_state.is_humongous()) { + gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i); + _failures = true; + return true; + } + } else { + if (cset_state.is_humongous()) { + gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i); + _failures = true; + return true; + } + if (hr->in_collection_set() != cset_state.is_in_cset()) { + gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u", + hr->in_collection_set(), cset_state.value(), i); + _failures = true; + return true; + } + if (cset_state.is_in_cset()) { + if (hr->is_young() != (cset_state.is_young())) { + gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u", + hr->is_young(), cset_state.value(), i); + _failures = true; + return true; + } + if (hr->is_old() != (cset_state.is_old())) { + gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u", + hr->is_old(), cset_state.value(), i); + _failures = true; + return true; + } + } + } + return false; + } + + bool failures() const { return _failures; } +}; + +bool G1CollectedHeap::check_cset_fast_test() { + G1CheckCSetFastTableClosure cl; + _hrm.iterate(&cl); + return !cl.failures(); +} +#endif // PRODUCT + +void G1CollectedHeap::cleanUpCardTable() { + G1SATBCardTableModRefBS* ct_bs = g1_barrier_set(); + double start = os::elapsedTime(); + + { + // Iterate over the dirty cards region list. + G1ParCleanupCTTask cleanup_task(ct_bs, this); + + set_par_threads(); + workers()->run_task(&cleanup_task); + set_par_threads(0); +#ifndef PRODUCT + if (G1VerifyCTCleanup || VerifyAfterGC) { + G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs); + heap_region_iterate(&cleanup_verifier); + } +#endif + } + + double elapsed = os::elapsedTime() - start; + g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0); +} + +void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) { + size_t pre_used = 0; + FreeRegionList local_free_list("Local List for CSet Freeing"); + + double young_time_ms = 0.0; + double non_young_time_ms = 0.0; + + // Since the collection set is a superset of the the young list, + // all we need to do to clear the young list is clear its + // head and length, and unlink any young regions in the code below + _young_list->clear(); + + G1CollectorPolicy* policy = g1_policy(); + + double start_sec = os::elapsedTime(); + bool non_young = true; + + HeapRegion* cur = cs_head; + int age_bound = -1; + size_t rs_lengths = 0; + + while (cur != NULL) { + assert(!is_on_master_free_list(cur), "sanity"); + if (non_young) { + if (cur->is_young()) { + double end_sec = os::elapsedTime(); + double elapsed_ms = (end_sec - start_sec) * 1000.0; + non_young_time_ms += elapsed_ms; + + start_sec = os::elapsedTime(); + non_young = false; + } + } else { + if (!cur->is_young()) { + double end_sec = os::elapsedTime(); + double elapsed_ms = (end_sec - start_sec) * 1000.0; + young_time_ms += elapsed_ms; + + start_sec = os::elapsedTime(); + non_young = true; + } + } + + rs_lengths += cur->rem_set()->occupied_locked(); + + HeapRegion* next = cur->next_in_collection_set(); + assert(cur->in_collection_set(), "bad CS"); + cur->set_next_in_collection_set(NULL); + clear_in_cset(cur); + + if (cur->is_young()) { + int index = cur->young_index_in_cset(); + assert(index != -1, "invariant"); + assert((uint) index < policy->young_cset_region_length(), "invariant"); + size_t words_survived = _surviving_young_words[index]; + cur->record_surv_words_in_group(words_survived); + + // At this point the we have 'popped' cur from the collection set + // (linked via next_in_collection_set()) but it is still in the + // young list (linked via next_young_region()). Clear the + // _next_young_region field. + cur->set_next_young_region(NULL); + } else { + int index = cur->young_index_in_cset(); + assert(index == -1, "invariant"); + } + + assert( (cur->is_young() && cur->young_index_in_cset() > -1) || + (!cur->is_young() && cur->young_index_in_cset() == -1), + "invariant" ); + + if (!cur->evacuation_failed()) { + MemRegion used_mr = cur->used_region(); + + // And the region is empty. + assert(!used_mr.is_empty(), "Should not have empty regions in a CS."); + pre_used += cur->used(); + free_region(cur, &local_free_list, false /* par */, true /* locked */); + } else { + cur->uninstall_surv_rate_group(); + if (cur->is_young()) { + cur->set_young_index_in_cset(-1); + } + cur->set_evacuation_failed(false); + // The region is now considered to be old. + cur->set_old(); + _old_set.add(cur); + evacuation_info.increment_collectionset_used_after(cur->used()); + } + cur = next; + } + + evacuation_info.set_regions_freed(local_free_list.length()); + policy->record_max_rs_lengths(rs_lengths); + policy->cset_regions_freed(); + + double end_sec = os::elapsedTime(); + double elapsed_ms = (end_sec - start_sec) * 1000.0; + + if (non_young) { + non_young_time_ms += elapsed_ms; + } else { + young_time_ms += elapsed_ms; + } + + prepend_to_freelist(&local_free_list); + decrement_summary_bytes(pre_used); + policy->phase_times()->record_young_free_cset_time_ms(young_time_ms); + policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms); +} + +class G1FreeHumongousRegionClosure : public HeapRegionClosure { + private: + FreeRegionList* _free_region_list; + HeapRegionSet* _proxy_set; + HeapRegionSetCount _humongous_regions_removed; + size_t _freed_bytes; + public: + + G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : + _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) { + } + + virtual bool doHeapRegion(HeapRegion* r) { + if (!r->is_starts_humongous()) { + return false; + } + + G1CollectedHeap* g1h = G1CollectedHeap::heap(); + + oop obj = (oop)r->bottom(); + CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap(); + + // The following checks whether the humongous object is live are sufficient. + // The main additional check (in addition to having a reference from the roots + // or the young gen) is whether the humongous object has a remembered set entry. + // + // A humongous object cannot be live if there is no remembered set for it + // because: + // - there can be no references from within humongous starts regions referencing + // the object because we never allocate other objects into them. + // (I.e. there are no intra-region references that may be missed by the + // remembered set) + // - as soon there is a remembered set entry to the humongous starts region + // (i.e. it has "escaped" to an old object) this remembered set entry will stay + // until the end of a concurrent mark. + // + // It is not required to check whether the object has been found dead by marking + // or not, in fact it would prevent reclamation within a concurrent cycle, as + // all objects allocated during that time are considered live. + // SATB marking is even more conservative than the remembered set. + // So if at this point in the collection there is no remembered set entry, + // nobody has a reference to it. + // At the start of collection we flush all refinement logs, and remembered sets + // are completely up-to-date wrt to references to the humongous object. + // + // Other implementation considerations: + // - never consider object arrays at this time because they would pose + // considerable effort for cleaning up the the remembered sets. This is + // required because stale remembered sets might reference locations that + // are currently allocated into. + uint region_idx = r->hrm_index(); + if (!g1h->is_humongous_reclaim_candidate(region_idx) || + !r->rem_set()->is_empty()) { + + if (G1TraceEagerReclaimHumongousObjects) { + gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d", + region_idx, + (size_t)obj->size() * HeapWordSize, + p2i(r->bottom()), + r->region_num(), + r->rem_set()->occupied(), + r->rem_set()->strong_code_roots_list_length(), + next_bitmap->isMarked(r->bottom()), + g1h->is_humongous_reclaim_candidate(region_idx), + obj->is_typeArray() + ); + } + + return false; + } + + guarantee(obj->is_typeArray(), + err_msg("Only eagerly reclaiming type arrays is supported, but the object " + PTR_FORMAT " is not.", + p2i(r->bottom()))); + + if (G1TraceEagerReclaimHumongousObjects) { + gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d", + region_idx, + (size_t)obj->size() * HeapWordSize, + p2i(r->bottom()), + r->region_num(), + r->rem_set()->occupied(), + r->rem_set()->strong_code_roots_list_length(), + next_bitmap->isMarked(r->bottom()), + g1h->is_humongous_reclaim_candidate(region_idx), + obj->is_typeArray() + ); + } + // Need to clear mark bit of the humongous object if already set. + if (next_bitmap->isMarked(r->bottom())) { + next_bitmap->clear(r->bottom()); + } + _freed_bytes += r->used(); + r->set_containing_set(NULL); + _humongous_regions_removed.increment(1u, r->capacity()); + g1h->free_humongous_region(r, _free_region_list, false); + + return false; + } + + HeapRegionSetCount& humongous_free_count() { + return _humongous_regions_removed; + } + + size_t bytes_freed() const { + return _freed_bytes; + } + + size_t humongous_reclaimed() const { + return _humongous_regions_removed.length(); + } +}; + +void G1CollectedHeap::eagerly_reclaim_humongous_regions() { + assert_at_safepoint(true); + + if (!G1EagerReclaimHumongousObjects || + (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) { + g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); + return; + } + + double start_time = os::elapsedTime(); + + FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); + + G1FreeHumongousRegionClosure cl(&local_cleanup_list); + heap_region_iterate(&cl); + + HeapRegionSetCount empty_set; + remove_from_old_sets(empty_set, cl.humongous_free_count()); + + G1HRPrinter* hrp = hr_printer(); + if (hrp->is_active()) { + FreeRegionListIterator iter(&local_cleanup_list); + while (iter.more_available()) { + HeapRegion* hr = iter.get_next(); + hrp->cleanup(hr); + } + } + + prepend_to_freelist(&local_cleanup_list); + decrement_summary_bytes(cl.bytes_freed()); + + g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, + cl.humongous_reclaimed()); +} + +// This routine is similar to the above but does not record +// any policy statistics or update free lists; we are abandoning +// the current incremental collection set in preparation of a +// full collection. After the full GC we will start to build up +// the incremental collection set again. +// This is only called when we're doing a full collection +// and is immediately followed by the tearing down of the young list. + +void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) { + HeapRegion* cur = cs_head; + + while (cur != NULL) { + HeapRegion* next = cur->next_in_collection_set(); + assert(cur->in_collection_set(), "bad CS"); + cur->set_next_in_collection_set(NULL); + clear_in_cset(cur); + cur->set_young_index_in_cset(-1); + cur = next; + } +} + +void G1CollectedHeap::set_free_regions_coming() { + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " + "setting free regions coming"); + } + + assert(!free_regions_coming(), "pre-condition"); + _free_regions_coming = true; +} + +void G1CollectedHeap::reset_free_regions_coming() { + assert(free_regions_coming(), "pre-condition"); + + { + MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); + _free_regions_coming = false; + SecondaryFreeList_lock->notify_all(); + } + + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : " + "reset free regions coming"); + } +} + +void G1CollectedHeap::wait_while_free_regions_coming() { + // Most of the time we won't have to wait, so let's do a quick test + // first before we take the lock. + if (!free_regions_coming()) { + return; + } + + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " + "waiting for free regions"); + } + + { + MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); + while (free_regions_coming()) { + SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag); + } + } + + if (G1ConcRegionFreeingVerbose) { + gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : " + "done waiting for free regions"); + } +} + +void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { + _young_list->push_region(hr); +} + +class NoYoungRegionsClosure: public HeapRegionClosure { +private: + bool _success; +public: + NoYoungRegionsClosure() : _success(true) { } + bool doHeapRegion(HeapRegion* r) { + if (r->is_young()) { + gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young", + p2i(r->bottom()), p2i(r->end())); + _success = false; + } + return false; + } + bool success() { return _success; } +}; + +bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) { + bool ret = _young_list->check_list_empty(check_sample); + + if (check_heap) { + NoYoungRegionsClosure closure; + heap_region_iterate(&closure); + ret = ret && closure.success(); + } + + return ret; +} + +class TearDownRegionSetsClosure : public HeapRegionClosure { +private: + HeapRegionSet *_old_set; + +public: + TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } + + bool doHeapRegion(HeapRegion* r) { + if (r->is_old()) { + _old_set->remove(r); + } else { + // We ignore free regions, we'll empty the free list afterwards. + // We ignore young regions, we'll empty the young list afterwards. + // We ignore humongous regions, we're not tearing down the + // humongous regions set. + assert(r->is_free() || r->is_young() || r->is_humongous(), + "it cannot be another type"); + } + return false; + } + + ~TearDownRegionSetsClosure() { + assert(_old_set->is_empty(), "post-condition"); + } +}; + +void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { + assert_at_safepoint(true /* should_be_vm_thread */); + + if (!free_list_only) { + TearDownRegionSetsClosure cl(&_old_set); + heap_region_iterate(&cl); + + // Note that emptying the _young_list is postponed and instead done as + // the first step when rebuilding the regions sets again. The reason for + // this is that during a full GC string deduplication needs to know if + // a collected region was young or old when the full GC was initiated. + } + _hrm.remove_all_free_regions(); +} + +class RebuildRegionSetsClosure : public HeapRegionClosure { +private: + bool _free_list_only; + HeapRegionSet* _old_set; + HeapRegionManager* _hrm; + size_t _total_used; + +public: + RebuildRegionSetsClosure(bool free_list_only, + HeapRegionSet* old_set, HeapRegionManager* hrm) : + _free_list_only(free_list_only), + _old_set(old_set), _hrm(hrm), _total_used(0) { + assert(_hrm->num_free_regions() == 0, "pre-condition"); + if (!free_list_only) { + assert(_old_set->is_empty(), "pre-condition"); + } + } + + bool doHeapRegion(HeapRegion* r) { + if (r->is_continues_humongous()) { + return false; + } + + if (r->is_empty()) { + // Add free regions to the free list + r->set_free(); + r->set_allocation_context(AllocationContext::system()); + _hrm->insert_into_free_list(r); + } else if (!_free_list_only) { + assert(!r->is_young(), "we should not come across young regions"); + + if (r->is_humongous()) { + // We ignore humongous regions, we left the humongous set unchanged + } else { + // Objects that were compacted would have ended up on regions + // that were previously old or free. + assert(r->is_free() || r->is_old(), "invariant"); + // We now consider them old, so register as such. + r->set_old(); + _old_set->add(r); + } + _total_used += r->used(); + } + + return false; + } + + size_t total_used() { + return _total_used; + } +}; + +void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { + assert_at_safepoint(true /* should_be_vm_thread */); + + if (!free_list_only) { + _young_list->empty_list(); + } + + RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); + heap_region_iterate(&cl); + + if (!free_list_only) { + _allocator->set_used(cl.total_used()); + } + assert(_allocator->used_unlocked() == recalculate_used(), + err_msg("inconsistent _allocator->used_unlocked(), " + "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT, + _allocator->used_unlocked(), recalculate_used())); +} + +void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) { + _refine_cte_cl->set_concurrent(concurrent); +} + +bool G1CollectedHeap::is_in_closed_subset(const void* p) const { + HeapRegion* hr = heap_region_containing(p); + return hr->is_in(p); +} + +// Methods for the mutator alloc region + +HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, + bool force) { + assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); + assert(!force || g1_policy()->can_expand_young_list(), + "if force is true we should be able to expand the young list"); + bool young_list_full = g1_policy()->is_young_list_full(); + if (force || !young_list_full) { + HeapRegion* new_alloc_region = new_region(word_size, + false /* is_old */, + false /* do_expand */); + if (new_alloc_region != NULL) { + set_region_short_lived_locked(new_alloc_region); + _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full); + check_bitmaps("Mutator Region Allocation", new_alloc_region); + return new_alloc_region; + } + } + return NULL; +} + +void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, + size_t allocated_bytes) { + assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); + assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); + + g1_policy()->add_region_to_incremental_cset_lhs(alloc_region); + _allocator->increase_used(allocated_bytes); + _hr_printer.retire(alloc_region); + // We update the eden sizes here, when the region is retired, + // instead of when it's allocated, since this is the point that its + // used space has been recored in _summary_bytes_used. + g1mm()->update_eden_size(); +} + +void G1CollectedHeap::set_par_threads() { + // Don't change the number of workers. Use the value previously set + // in the workgroup. + uint n_workers = workers()->active_workers(); + assert(UseDynamicNumberOfGCThreads || + n_workers == workers()->total_workers(), + "Otherwise should be using the total number of workers"); + if (n_workers == 0) { + assert(false, "Should have been set in prior evacuation pause."); + n_workers = ParallelGCThreads; + workers()->set_active_workers(n_workers); + } + set_par_threads(n_workers); +} + +// Methods for the GC alloc regions + +HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, + uint count, + InCSetState dest) { + assert(FreeList_lock->owned_by_self(), "pre-condition"); + + if (count < g1_policy()->max_regions(dest)) { + const bool is_survivor = (dest.is_young()); + HeapRegion* new_alloc_region = new_region(word_size, + !is_survivor, + true /* do_expand */); + if (new_alloc_region != NULL) { + // We really only need to do this for old regions given that we + // should never scan survivors. But it doesn't hurt to do it + // for survivors too. + new_alloc_region->record_timestamp(); + if (is_survivor) { + new_alloc_region->set_survivor(); + _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor); + check_bitmaps("Survivor Region Allocation", new_alloc_region); + } else { + new_alloc_region->set_old(); + _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old); + check_bitmaps("Old Region Allocation", new_alloc_region); + } + bool during_im = g1_policy()->during_initial_mark_pause(); + new_alloc_region->note_start_of_copying(during_im); + return new_alloc_region; + } + } + return NULL; +} + +void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, + size_t allocated_bytes, + InCSetState dest) { + bool during_im = g1_policy()->during_initial_mark_pause(); + alloc_region->note_end_of_copying(during_im); + g1_policy()->record_bytes_copied_during_gc(allocated_bytes); + if (dest.is_young()) { + young_list()->add_survivor_region(alloc_region); + } else { + _old_set.add(alloc_region); + } + _hr_printer.retire(alloc_region); +} + +// Heap region set verification + +class VerifyRegionListsClosure : public HeapRegionClosure { +private: + HeapRegionSet* _old_set; + HeapRegionSet* _humongous_set; + HeapRegionManager* _hrm; + +public: + HeapRegionSetCount _old_count; + HeapRegionSetCount _humongous_count; + HeapRegionSetCount _free_count; + + VerifyRegionListsClosure(HeapRegionSet* old_set, + HeapRegionSet* humongous_set, + HeapRegionManager* hrm) : + _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm), + _old_count(), _humongous_count(), _free_count(){ } + + bool doHeapRegion(HeapRegion* hr) { + if (hr->is_continues_humongous()) { + return false; + } + + if (hr->is_young()) { + // TODO + } else if (hr->is_starts_humongous()) { + assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index())); + _humongous_count.increment(1u, hr->capacity()); + } else if (hr->is_empty()) { + assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index())); + _free_count.increment(1u, hr->capacity()); + } else if (hr->is_old()) { + assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index())); + _old_count.increment(1u, hr->capacity()); + } else { + ShouldNotReachHere(); + } + return false; + } + + void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) { + guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length())); + guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, + old_set->total_capacity_bytes(), _old_count.capacity())); + + guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length())); + guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, + humongous_set->total_capacity_bytes(), _humongous_count.capacity())); + + guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length())); + guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, + free_list->total_capacity_bytes(), _free_count.capacity())); + } +}; + +void G1CollectedHeap::verify_region_sets() { + assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); + + // First, check the explicit lists. + _hrm.verify(); + { + // Given that a concurrent operation might be adding regions to + // the secondary free list we have to take the lock before + // verifying it. + MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); + _secondary_free_list.verify_list(); + } + + // If a concurrent region freeing operation is in progress it will + // be difficult to correctly attributed any free regions we come + // across to the correct free list given that they might belong to + // one of several (free_list, secondary_free_list, any local lists, + // etc.). So, if that's the case we will skip the rest of the + // verification operation. Alternatively, waiting for the concurrent + // operation to complete will have a non-trivial effect on the GC's + // operation (no concurrent operation will last longer than the + // interval between two calls to verification) and it might hide + // any issues that we would like to catch during testing. + if (free_regions_coming()) { + return; + } + + // Make sure we append the secondary_free_list on the free_list so + // that all free regions we will come across can be safely + // attributed to the free_list. + append_secondary_free_list_if_not_empty_with_lock(); + + // Finally, make sure that the region accounting in the lists is + // consistent with what we see in the heap. + + VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm); + heap_region_iterate(&cl); + cl.verify_counts(&_old_set, &_humongous_set, &_hrm); +} + +// Optimized nmethod scanning + +class RegisterNMethodOopClosure: public OopClosure { + G1CollectedHeap* _g1h; + nmethod* _nm; + + template void do_oop_work(T* p) { + T heap_oop = oopDesc::load_heap_oop(p); + if (!oopDesc::is_null(heap_oop)) { + oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); + HeapRegion* hr = _g1h->heap_region_containing(obj); + assert(!hr->is_continues_humongous(), + err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT + " starting at "HR_FORMAT, + p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); + + // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. + hr->add_strong_code_root_locked(_nm); + } + } + +public: + RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : + _g1h(g1h), _nm(nm) {} + + void do_oop(oop* p) { do_oop_work(p); } + void do_oop(narrowOop* p) { do_oop_work(p); } +}; + +class UnregisterNMethodOopClosure: public OopClosure { + G1CollectedHeap* _g1h; + nmethod* _nm; + + template void do_oop_work(T* p) { + T heap_oop = oopDesc::load_heap_oop(p); + if (!oopDesc::is_null(heap_oop)) { + oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); + HeapRegion* hr = _g1h->heap_region_containing(obj); + assert(!hr->is_continues_humongous(), + err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT + " starting at "HR_FORMAT, + p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()))); + + hr->remove_strong_code_root(_nm); + } + } + +public: + UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : + _g1h(g1h), _nm(nm) {} + + void do_oop(oop* p) { do_oop_work(p); } + void do_oop(narrowOop* p) { do_oop_work(p); } +}; + +void G1CollectedHeap::register_nmethod(nmethod* nm) { + CollectedHeap::register_nmethod(nm); + + guarantee(nm != NULL, "sanity"); + RegisterNMethodOopClosure reg_cl(this, nm); + nm->oops_do(®_cl); +} + +void G1CollectedHeap::unregister_nmethod(nmethod* nm) { + CollectedHeap::unregister_nmethod(nm); + + guarantee(nm != NULL, "sanity"); + UnregisterNMethodOopClosure reg_cl(this, nm); + nm->oops_do(®_cl, true); +} + +void G1CollectedHeap::purge_code_root_memory() { + double purge_start = os::elapsedTime(); + G1CodeRootSet::purge(); + double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; + g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); +} + +class RebuildStrongCodeRootClosure: public CodeBlobClosure { + G1CollectedHeap* _g1h; + +public: + RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : + _g1h(g1h) {} + + void do_code_blob(CodeBlob* cb) { + nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; + if (nm == NULL) { + return; + } + + if (ScavengeRootsInCode) { + _g1h->register_nmethod(nm); + } + } +}; + +void G1CollectedHeap::rebuild_strong_code_roots() { + RebuildStrongCodeRootClosure blob_cl(this); + CodeCache::blobs_do(&blob_cl); +}