/* * Copyright (c) 2001, 2017, 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 "classfile/symbolTable.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/g1Allocator.inline.hpp" #include "gc/g1/g1CollectedHeap.inline.hpp" #include "gc/g1/g1CollectionSet.hpp" #include "gc/g1/g1CollectorPolicy.hpp" #include "gc/g1/g1CollectorState.hpp" #include "gc/g1/g1EvacStats.inline.hpp" #include "gc/g1/g1GCPhaseTimes.hpp" #include "gc/g1/g1HeapSizingPolicy.hpp" #include "gc/g1/g1HeapTransition.hpp" #include "gc/g1/g1HeapVerifier.hpp" #include "gc/g1/g1HotCardCache.hpp" #include "gc/g1/g1MarkSweep.hpp" #include "gc/g1/g1OopClosures.inline.hpp" #include "gc/g1/g1ParScanThreadState.inline.hpp" #include "gc/g1/g1Policy.hpp" #include "gc/g1/g1RegionToSpaceMapper.hpp" #include "gc/g1/g1RemSet.inline.hpp" #include "gc/g1/g1RootClosures.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/suspendibleThreadSet.hpp" #include "gc/g1/vm_operations_g1.hpp" #include "gc/shared/gcHeapSummary.hpp" #include "gc/shared/gcId.hpp" #include "gc/shared/gcLocker.inline.hpp" #include "gc/shared/gcTimer.hpp" #include "gc/shared/gcTrace.hpp" #include "gc/shared/gcTraceTime.inline.hpp" #include "gc/shared/generationSpec.hpp" #include "gc/shared/isGCActiveMark.hpp" #include "gc/shared/preservedMarks.inline.hpp" #include "gc/shared/referenceProcessor.inline.hpp" #include "gc/shared/taskqueue.inline.hpp" #include "logging/log.hpp" #include "memory/allocation.hpp" #include "memory/iterator.hpp" #include "memory/resourceArea.hpp" #include "oops/oop.inline.hpp" #include "prims/resolvedMethodTable.hpp" #include "runtime/atomic.hpp" #include "runtime/init.hpp" #include "runtime/orderAccess.inline.hpp" #include "runtime/vmThread.hpp" #include "utilities/align.hpp" #include "utilities/globalDefinitions.hpp" #include "utilities/stack.inline.hpp" size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; // 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.) class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { private: size_t _num_dirtied; G1CollectedHeap* _g1h; G1SATBCardTableLoggingModRefBS* _g1_bs; HeapRegion* region_for_card(jbyte* card_ptr) const { return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr)); } bool will_become_free(HeapRegion* hr) const { // A region will be freed by free_collection_set if the region is in the // collection set and has not had an evacuation failure. return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); } public: RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { } bool do_card_ptr(jbyte* card_ptr, uint worker_i) { HeapRegion* hr = region_for_card(card_ptr); // Should only dirty cards in regions that won't be freed. if (!will_become_free(hr)) { *card_ptr = CardTableModRefBS::dirty_card_val(); _num_dirtied++; } return true; } size_t num_dirtied() const { return _num_dirtied; } }; 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); } // 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_pinned(); } // 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()) { log_develop_trace(gc, freelist)("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); log_develop_trace(gc, freelist)("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); } log_develop_trace(gc, freelist)("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()) { log_develop_trace(gc, freelist)("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) { log_develop_trace(gc, freelist)("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"); log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 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. uint last = first + num_regions - 1; // 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 top of the new object. HeapWord* obj_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); // Next, pad out the unused tail of the last region with filler // objects, for improved usage accounting. // How many words we use for filler objects. size_t word_fill_size = word_size_sum - word_size; // How many words memory we "waste" which cannot hold a filler object. size_t words_not_fillable = 0; if (word_fill_size >= min_fill_size()) { fill_with_objects(obj_top, word_fill_size); } else if (word_fill_size > 0) { // We have space to fill, but we cannot fit an object there. words_not_fillable = word_fill_size; word_fill_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(obj_top, word_fill_size); 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); } // 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, we will update the top fields of the "continues humongous" // regions except the last one. for (uint i = first; i < last; ++i) { hr = region_at(i); hr->set_top(hr->end()); } hr = region_at(last); // If we cannot fit a filler object, we must set top to the end // of the humongous object, otherwise we cannot iterate the heap // and the BOT will not be complete. hr->set_top(hr->end() - words_not_fillable); assert(hr->bottom() < obj_top && obj_top <= hr->end(), "obj_top should be in last region"); _verifier->check_bitmaps("Humongous Region Allocation", first_hr); assert(words_not_fillable == 0 || first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), "Miscalculation in humongous allocation"); increase_used((word_size_sum - words_not_fillable) * HeapWordSize); for (uint i = first; i <= last; ++i) { hr = region_at(i); _humongous_set.add(hr); _hr_printer.alloc(hr); } return new_obj; } size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; } // 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 */); _verifier->verify_region_sets_optional(); uint first = G1_NO_HRM_INDEX; uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 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. log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", word_size * HeapWordSize); _hrm.expand_at(first, obj_regions, workers()); 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(); } _verifier->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)) { log_warning(gc)("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->attempt_allocation_locked(word_size, context); if (result != NULL) { return result; } if (GCLocker::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->attempt_allocation_force(word_size, context); 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 (GCLocker::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. GCLocker::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->attempt_allocation(word_size, context); if (result != NULL) { return result; } // Give a warning if we seem to be looping forever. if ((QueuedAllocationWarningCount > 0) && (try_count % QueuedAllocationWarningCount == 0)) { log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() " "retries %d times", try_count); } } ShouldNotReachHere(); return NULL; } void G1CollectedHeap::begin_archive_alloc_range() { assert_at_safepoint(true /* should_be_vm_thread */); if (_archive_allocator == NULL) { _archive_allocator = G1ArchiveAllocator::create_allocator(this); } } bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { // Allocations in archive regions cannot be of a size that would be considered // humongous even for a minimum-sized region, because G1 region sizes/boundaries // may be different at archive-restore time. return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); } HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { assert_at_safepoint(true /* should_be_vm_thread */); assert(_archive_allocator != NULL, "_archive_allocator not initialized"); if (is_archive_alloc_too_large(word_size)) { return NULL; } return _archive_allocator->archive_mem_allocate(word_size); } void G1CollectedHeap::end_archive_alloc_range(GrowableArray* ranges, size_t end_alignment_in_bytes) { assert_at_safepoint(true /* should_be_vm_thread */); assert(_archive_allocator != NULL, "_archive_allocator not initialized"); // Call complete_archive to do the real work, filling in the MemRegion // array with the archive regions. _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); delete _archive_allocator; _archive_allocator = NULL; } bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { assert(ranges != NULL, "MemRegion array NULL"); assert(count != 0, "No MemRegions provided"); MemRegion reserved = _hrm.reserved(); for (size_t i = 0; i < count; i++) { if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { return false; } } return true; } bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) { assert(!is_init_completed(), "Expect to be called at JVM init time"); assert(ranges != NULL, "MemRegion array NULL"); assert(count != 0, "No MemRegions provided"); MutexLockerEx x(Heap_lock); MemRegion reserved = _hrm.reserved(); HeapWord* prev_last_addr = NULL; HeapRegion* prev_last_region = NULL; // Temporarily disable pretouching of heap pages. This interface is used // when mmap'ing archived heap data in, so pre-touching is wasted. FlagSetting fs(AlwaysPreTouch, false); // Enable archive object checking used by G1MarkSweep. We have to let it know // about each archive range, so that objects in those ranges aren't marked. G1ArchiveAllocator::enable_archive_object_check(); // For each specified MemRegion range, allocate the corresponding G1 // regions and mark them as archive regions. We expect the ranges in // ascending starting address order, without overlap. for (size_t i = 0; i < count; i++) { MemRegion curr_range = ranges[i]; HeapWord* start_address = curr_range.start(); size_t word_size = curr_range.word_size(); HeapWord* last_address = curr_range.last(); size_t commits = 0; guarantee(reserved.contains(start_address) && reserved.contains(last_address), "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", p2i(start_address), p2i(last_address)); guarantee(start_address > prev_last_addr, "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , p2i(start_address), p2i(prev_last_addr)); prev_last_addr = last_address; // Check for ranges that start in the same G1 region in which the previous // range ended, and adjust the start address so we don't try to allocate // the same region again. If the current range is entirely within that // region, skip it, just adjusting the recorded top. HeapRegion* start_region = _hrm.addr_to_region(start_address); if ((prev_last_region != NULL) && (start_region == prev_last_region)) { start_address = start_region->end(); if (start_address > last_address) { increase_used(word_size * HeapWordSize); start_region->set_top(last_address + 1); continue; } start_region->set_top(start_address); curr_range = MemRegion(start_address, last_address + 1); start_region = _hrm.addr_to_region(start_address); } // Perform the actual region allocation, exiting if it fails. // Then note how much new space we have allocated. if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { return false; } increase_used(word_size * HeapWordSize); if (commits != 0) { log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", HeapRegion::GrainWords * HeapWordSize * commits); } // Mark each G1 region touched by the range as archive, add it to the old set, // and set the allocation context and top. HeapRegion* curr_region = _hrm.addr_to_region(start_address); HeapRegion* last_region = _hrm.addr_to_region(last_address); prev_last_region = last_region; while (curr_region != NULL) { assert(curr_region->is_empty() && !curr_region->is_pinned(), "Region already in use (index %u)", curr_region->hrm_index()); curr_region->set_allocation_context(AllocationContext::system()); curr_region->set_archive(); _hr_printer.alloc(curr_region); _old_set.add(curr_region); if (curr_region != last_region) { curr_region->set_top(curr_region->end()); curr_region = _hrm.next_region_in_heap(curr_region); } else { curr_region->set_top(last_address + 1); curr_region = NULL; } } // Notify mark-sweep of the archive range. G1ArchiveAllocator::set_range_archive(curr_range, true); } return true; } void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { assert(!is_init_completed(), "Expect to be called at JVM init time"); assert(ranges != NULL, "MemRegion array NULL"); assert(count != 0, "No MemRegions provided"); MemRegion reserved = _hrm.reserved(); HeapWord *prev_last_addr = NULL; HeapRegion* prev_last_region = NULL; // For each MemRegion, create filler objects, if needed, in the G1 regions // that contain the address range. The address range actually within the // MemRegion will not be modified. That is assumed to have been initialized // elsewhere, probably via an mmap of archived heap data. MutexLockerEx x(Heap_lock); for (size_t i = 0; i < count; i++) { HeapWord* start_address = ranges[i].start(); HeapWord* last_address = ranges[i].last(); assert(reserved.contains(start_address) && reserved.contains(last_address), "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", p2i(start_address), p2i(last_address)); assert(start_address > prev_last_addr, "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , p2i(start_address), p2i(prev_last_addr)); HeapRegion* start_region = _hrm.addr_to_region(start_address); HeapRegion* last_region = _hrm.addr_to_region(last_address); HeapWord* bottom_address = start_region->bottom(); // Check for a range beginning in the same region in which the // previous one ended. if (start_region == prev_last_region) { bottom_address = prev_last_addr + 1; } // Verify that the regions were all marked as archive regions by // alloc_archive_regions. HeapRegion* curr_region = start_region; while (curr_region != NULL) { guarantee(curr_region->is_archive(), "Expected archive region at index %u", curr_region->hrm_index()); if (curr_region != last_region) { curr_region = _hrm.next_region_in_heap(curr_region); } else { curr_region = NULL; } } prev_last_addr = last_address; prev_last_region = last_region; // Fill the memory below the allocated range with dummy object(s), // if the region bottom does not match the range start, or if the previous // range ended within the same G1 region, and there is a gap. if (start_address != bottom_address) { size_t fill_size = pointer_delta(start_address, bottom_address); G1CollectedHeap::fill_with_objects(bottom_address, fill_size); increase_used(fill_size * HeapWordSize); } } } inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size, uint* gc_count_before_ret, uint* gclocker_retry_count_ret) { assert_heap_not_locked_and_not_at_safepoint(); assert(!is_humongous(word_size), "attempt_allocation() should not " "be called for humongous allocation requests"); AllocationContext_t context = AllocationContext::current(); HeapWord* result = _allocator->attempt_allocation(word_size, context); if (result == NULL) { result = attempt_allocation_slow(word_size, context, gc_count_before_ret, gclocker_retry_count_ret); } assert_heap_not_locked(); if (result != NULL) { dirty_young_block(result, word_size); } return result; } void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { assert(!is_init_completed(), "Expect to be called at JVM init time"); assert(ranges != NULL, "MemRegion array NULL"); assert(count != 0, "No MemRegions provided"); MemRegion reserved = _hrm.reserved(); HeapWord* prev_last_addr = NULL; HeapRegion* prev_last_region = NULL; size_t size_used = 0; size_t uncommitted_regions = 0; // For each Memregion, free the G1 regions that constitute it, and // notify mark-sweep that the range is no longer to be considered 'archive.' MutexLockerEx x(Heap_lock); for (size_t i = 0; i < count; i++) { HeapWord* start_address = ranges[i].start(); HeapWord* last_address = ranges[i].last(); assert(reserved.contains(start_address) && reserved.contains(last_address), "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", p2i(start_address), p2i(last_address)); assert(start_address > prev_last_addr, "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , p2i(start_address), p2i(prev_last_addr)); size_used += ranges[i].byte_size(); prev_last_addr = last_address; HeapRegion* start_region = _hrm.addr_to_region(start_address); HeapRegion* last_region = _hrm.addr_to_region(last_address); // Check for ranges that start in the same G1 region in which the previous // range ended, and adjust the start address so we don't try to free // the same region again. If the current range is entirely within that // region, skip it. if (start_region == prev_last_region) { start_address = start_region->end(); if (start_address > last_address) { continue; } start_region = _hrm.addr_to_region(start_address); } prev_last_region = last_region; // After verifying that each region was marked as an archive region by // alloc_archive_regions, set it free and empty and uncommit it. HeapRegion* curr_region = start_region; while (curr_region != NULL) { guarantee(curr_region->is_archive(), "Expected archive region at index %u", curr_region->hrm_index()); uint curr_index = curr_region->hrm_index(); _old_set.remove(curr_region); curr_region->set_free(); curr_region->set_top(curr_region->bottom()); if (curr_region != last_region) { curr_region = _hrm.next_region_in_heap(curr_region); } else { curr_region = NULL; } _hrm.shrink_at(curr_index, 1); uncommitted_regions++; } // Notify mark-sweep that this is no longer an archive range. G1ArchiveAllocator::set_range_archive(ranges[i], false); } if (uncommitted_regions != 0) { log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); } decrease_used(size_used); } 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) { size_t size_in_regions = humongous_obj_size_in_regions(word_size); g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); return result; } if (GCLocker::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 (GCLocker::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. GCLocker::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)) { log_warning(gc)("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->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region, "the current alloc region was unexpectedly found to be non-NULL"); if (!is_humongous(word_size)) { return _allocator->attempt_allocation_locked(word_size, context); } else { HeapWord* result = humongous_obj_allocate(word_size, context); if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { collector_state()->set_initiate_conc_mark_if_possible(true); } 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(); _g1h->reset_gc_time_stamps(r); 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"); } else { 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; RebuildRSOopClosure _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"); _hr_printer->post_compaction(hr); return false; } PostCompactionPrinterClosure(G1HRPrinter* hr_printer) : _hr_printer(hr_printer) { } }; void G1CollectedHeap::print_hrm_post_compaction() { if (_hr_printer.is_active()) { PostCompactionPrinterClosure cl(hr_printer()); heap_region_iterate(&cl); } } bool G1CollectedHeap::do_full_collection(bool explicit_gc, bool clear_all_soft_refs) { assert_at_safepoint(true /* should_be_vm_thread */); if (GCLocker::check_active_before_gc()) { return false; } STWGCTimer* gc_timer = G1MarkSweep::gc_timer(); gc_timer->register_gc_start(); SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer(); GCIdMark gc_id_mark; gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start()); SvcGCMarker sgcm(SvcGCMarker::FULL); ResourceMark rm; print_heap_before_gc(); print_heap_regions(); trace_heap_before_gc(gc_tracer); size_t metadata_prev_used = MetaspaceAux::used_bytes(); _verifier->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(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); GCTraceCPUTime tcpu; { GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); TraceCollectorStats tcs(g1mm()->full_collection_counters()); TraceMemoryManagerStats tms(true /* fullGC */, gc_cause()); G1HeapTransition heap_transition(this); 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"); _verifier->verify_before_gc(); _verifier->check_bitmaps("Full GC Start"); pre_full_gc_dump(gc_timer); #if defined(COMPILER2) || INCLUDE_JVMCI DerivedPointerTable::clear(); #endif // 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. 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 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(collection_set()); tear_down_region_sets(false /* free_list_only */); collector_state()->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(); #if defined(COMPILER2) || INCLUDE_JVMCI DerivedPointerTable::update_pointers(); #endif 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_if_necessary_after_full_collection(); // We should do this after we potentially resize the heap so // that all the COMMIT / UNCOMMIT events are generated before // the compaction events. print_hrm_post_compaction(); 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()); workers()->update_active_workers(n_workers); log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers()); ParRebuildRSTask rebuild_rs_task(this); workers()->run_task(&rebuild_rs_task); // 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"); // At this point there should be no regions in the // entire heap tagged as young. assert(check_young_list_empty(), "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(); _verifier->verify_region_sets_optional(); _verifier->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 // G1ConcurrentMark::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) { GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); _cm->clear_prev_bitmap(workers()); } _verifier->check_bitmaps("Full GC End"); start_new_collection_set(); _allocator->init_mutator_alloc_region(); g1_policy()->record_full_collection_end(); // 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); heap_transition.print(); print_heap_after_gc(); print_heap_regions(); 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) { // Currently, there is no facility in the do_full_collection(bool) API to notify // the caller that 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_full_collection(true, /* explicit_gc */ clear_all_soft_refs); } void G1CollectedHeap::resize_if_necessary_after_full_collection() { // Include 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, "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; log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); expand(expand_bytes, _workers); // 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; log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio); shrink(shrink_bytes); } } HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, AllocationContext_t context, bool do_gc, bool clear_all_soft_refs, bool expect_null_mutator_alloc_region, bool* gc_succeeded) { *gc_succeeded = true; // Let's attempt the allocation first. HeapWord* result = attempt_allocation_at_safepoint(word_size, context, expect_null_mutator_alloc_region); if (result != NULL) { assert(*gc_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(*gc_succeeded, "sanity"); return result; } if (do_gc) { // Expansion didn't work, we'll try to do a Full GC. *gc_succeeded = do_full_collection(false, /* explicit_gc */ clear_all_soft_refs); } return NULL; } HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, AllocationContext_t context, bool* succeeded) { assert_at_safepoint(true /* should_be_vm_thread */); // Attempts to allocate followed by Full GC. HeapWord* result = satisfy_failed_allocation_helper(word_size, context, true, /* do_gc */ false, /* clear_all_soft_refs */ false, /* expect_null_mutator_alloc_region */ succeeded); if (result != NULL || !*succeeded) { return result; } // Attempts to allocate followed by Full GC that will collect all soft references. result = satisfy_failed_allocation_helper(word_size, context, true, /* do_gc */ true, /* clear_all_soft_refs */ true, /* expect_null_mutator_alloc_region */ succeeded); if (result != NULL || !*succeeded) { return result; } // Attempts to allocate, no GC result = satisfy_failed_allocation_helper(word_size, context, false, /* do_gc */ false, /* clear_all_soft_refs */ true, /* expect_null_mutator_alloc_region */ succeeded); 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 */); _verifier->verify_region_sets_optional(); size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", word_size * HeapWordSize); if (expand(expand_bytes, _workers)) { _hrm.verify_optional(); _verifier->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, WorkGang* pretouch_workers, double* expand_time_ms) { size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); aligned_expand_bytes = align_up(aligned_expand_bytes, HeapRegion::GrainBytes); log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", expand_bytes, aligned_expand_bytes); if (is_maximal_no_gc()) { log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); return false; } double expand_heap_start_time_sec = os::elapsedTime(); 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, pretouch_workers); if (expand_time_ms != NULL) { *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; } 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 { log_debug(gc, ergo, heap)("Did not expand the heap (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_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; log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B", shrink_bytes, aligned_shrink_bytes, shrunk_bytes); if (num_regions_removed > 0) { g1_policy()->record_new_heap_size(num_regions()); } else { log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); } } void G1CollectedHeap::shrink(size_t shrink_bytes) { _verifier->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(); _verifier->verify_region_sets_optional(); } // Public methods. G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : CollectedHeap(), _collector_policy(collector_policy), _g1_policy(create_g1_policy()), _collection_set(this, _g1_policy), _dirty_card_queue_set(false), _is_alive_closure_cm(this), _is_alive_closure_stw(this), _ref_processor_cm(NULL), _ref_processor_stw(NULL), _bot(NULL), _hot_card_cache(NULL), _g1_rem_set(NULL), _cg1r(NULL), _g1mm(NULL), _preserved_marks_set(true /* in_c_heap */), _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), _archive_allocator(NULL), _free_regions_coming(false), _gc_time_stamp(0), _summary_bytes_used(0), _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), _old_evac_stats("Old", OldPLABSize, PLABWeight), _expand_heap_after_alloc_failure(true), _old_marking_cycles_started(0), _old_marking_cycles_completed(0), _in_cset_fast_test(), _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) { _workers = new WorkGang("GC Thread", ParallelGCThreads, /* are_GC_task_threads */true, /* are_ConcurrentGC_threads */false); _workers->initialize_workers(); _verifier = new G1HeapVerifier(this); _allocator = G1Allocator::create_allocator(this); _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); // Override the default _filler_array_max_size so that no humongous filler // objects are created. _filler_array_max_size = _humongous_object_threshold_in_words; uint n_queues = ParallelGCThreads; _task_queues = new RefToScanQueueSet(n_queues); _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); for (uint 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(); } // 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); os::trace_page_sizes_for_requested_size(description, size, preferred_page_size, rs.alignment(), rs.base(), rs.size()); return result; } jint G1CollectedHeap::initialize_concurrent_refinement() { jint ecode = JNI_OK; _cg1r = ConcurrentG1Refine::create(&ecode); return ecode; } jint G1CollectedHeap::initialize() { CollectedHeap::pre_initialize(); os::enable_vtime(); // Necessary to satisfy locking discipline assertions. MutexLocker x(Heap_lock); // 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"); // 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); // Create the hot card cache. _hot_card_cache = new G1HotCardCache(this); // 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("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", G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), G1BlockOffsetTable::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 = G1CMBitMap::compute_size(g1_rs.size()); G1RegionToSpaceMapper* prev_bitmap_storage = create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); G1RegionToSpaceMapper* next_bitmap_storage = create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::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. _hot_card_cache->initialize(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"); // Also create a G1 rem set. _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache); _g1_rem_set->initialize(max_capacity(), max_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 = new G1BlockOffsetTable(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 G1ConcurrentMark data structure and thread. // (Must do this late, so that "max_regions" is defined.) _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); if (_cm == NULL || !_cm->completed_initialization()) { vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); return JNI_ENOMEM; } _cmThread = _cm->cmThread(); // Now expand into the initial heap size. if (!expand(init_byte_size, _workers)) { vm_shutdown_during_initialization("Failed to allocate initial heap."); return JNI_ENOMEM; } // Perform any initialization actions delegated to the policy. g1_policy()->init(this, &_collection_set); JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, SATB_Q_FL_lock, G1SATBProcessCompletedThreshold, Shared_SATB_Q_lock); jint ecode = initialize_concurrent_refinement(); if (ecode != JNI_OK) { return ecode; } JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, DirtyCardQ_FL_lock, (int)concurrent_g1_refine()->yellow_zone(), (int)concurrent_g1_refine()->red_zone(), Shared_DirtyCardQ_lock, NULL, // fl_owner true); // init_free_ids dirty_card_queue_set().initialize(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(); _preserved_marks_set.init(ParallelGCThreads); _collection_set.initialize(max_regions()); 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. logging) // 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() { 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 ParallelGCThreads, // degree of mt processing (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 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 ParallelGCThreads, // degree of mt processing (ParallelGCThreads > 1), // mt discovery ParallelGCThreads, // degree of mt discovery true, // Reference discovery is atomic &_is_alive_closure_stw); // is alive closure // (for efficiency/performance) } CollectorPolicy* G1CollectedHeap::collector_policy() const { return _collector_policy; } size_t G1CollectedHeap::capacity() const { return _hrm.length() * HeapRegion::GrainBytes; } void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) { hr->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) { log_error(gc, verify)("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_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { _hot_card_cache->drain(cl, worker_i); } void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); size_t n_completed_buffers = 0; while (dcqs.apply_closure_during_gc(cl, worker_i)) { 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 { size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); if (_archive_allocator != NULL) { result += _archive_allocator->used(); } return result; } size_t G1CollectedHeap::used_unlocked() const { return _summary_bytes_used; } class SumUsedClosure: public HeapRegionClosure { size_t _used; public: SumUsedClosure() : _used(0) {} bool doHeapRegion(HeapRegion* r) { _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::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { switch (cause) { case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; case GCCause::_update_allocation_context_stats_inc: return true; case GCCause::_wb_conc_mark: return true; default : return false; } } bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { switch (cause) { case GCCause::_gc_locker: return GCLockerInvokesConcurrent; case GCCause::_g1_humongous_allocation: return true; default: return is_user_requested_concurrent_full_gc(cause); } } #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"); // _filler_array_max_size is set to humongous object threshold // but temporarily change it to use CollectedHeap::fill_with_object(). SizeTFlagSetting fs(_filler_array_max_size, word_size); 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, "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), "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), "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->set_idle(); } // 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::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 (GCLocker::is_active_and_needs_gc()) { GCLocker::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() should successfully // return the containing region. HeapRegion* hr = heap_region_containing(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. // 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) const { _hrm.par_iterate(cl, worker_id, hrclaimer); } void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { _collection_set.iterate(cl); } void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); } HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const { HeapRegion* result = _hrm.next_region_in_heap(from); while (result != NULL && result->is_pinned()) { 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() - _survivor.length()) * HeapRegion::GrainBytes; } size_t G1CollectedHeap::tlab_used(Thread* ignored) const { return _eden.length() * HeapRegion::GrainBytes; } // For G1 TLABs should not contain humongous objects, so the maximum TLAB size // must be equal to the humongous object limit. size_t G1CollectedHeap::max_tlab_size() const { return align_down(_humongous_object_threshold_in_words, MinObjAlignment); } size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { AllocationContext_t context = AllocationContext::current(); return _allocator->unsafe_max_tlab_alloc(context); } size_t G1CollectedHeap::max_capacity() const { return _hrm.reserved().byte_size(); } jlong G1CollectedHeap::millis_since_last_gc() { // See the notes in GenCollectedHeap::millis_since_last_gc() // for more information about the implementation. jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - _g1_policy->collection_pause_end_millis(); if (ret_val < 0) { log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT ". returning zero instead.", ret_val); return 0; } return ret_val; } void G1CollectedHeap::prepare_for_verify() { _verifier->prepare_for_verify(); } void G1CollectedHeap::verify(VerifyOption vo) { _verifier->verify(vo); } bool G1CollectedHeap::supports_concurrent_phase_control() const { return true; } const char* const* G1CollectedHeap::concurrent_phases() const { return _cmThread->concurrent_phases(); } bool G1CollectedHeap::request_concurrent_phase(const char* phase) { return _cmThread->request_concurrent_phase(phase); } 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() && !hr->is_archive(); 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: { HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj); return !obj->is_gc_marked() && !hr->is_archive(); } default: ShouldNotReachHere(); } return false; // keep some compilers happy } void G1CollectedHeap::print_heap_regions() const { Log(gc, heap, region) log; if (log.is_trace()) { ResourceMark rm; print_regions_on(log.trace_stream()); } } 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_regions_count(); st->print("%u young (" SIZE_FORMAT "K), ", young_regions, (size_t) young_regions * HeapRegion::GrainBytes / K); uint survivor_regions = survivor_regions_count(); 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_regions_on(outputStream* st) const { st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " "HS=humongous(starts), HC=humongous(continues), " "CS=collection set, F=free, A=archive, TS=gc time stamp, " "AC=allocation context, " "TAMS=top-at-mark-start (previous, next)"); PrintRegionClosure blk(st); heap_region_iterate(&blk); } void G1CollectedHeap::print_extended_on(outputStream* st) const { print_on(st); // Print the per-region information. print_regions_on(st); } 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); // also prints the sample thread 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); _cm->threads_do(tc); _cg1r->threads_do(tc); // also iterates over the sample thread if (G1StringDedup::is_enabled()) { G1StringDedup::threads_do(tc); } } void G1CollectedHeap::print_tracing_info() const { g1_rem_set()->print_summary_info(); concurrent_mark()->print_summary_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; tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); if (occupied == 0) { tty->print_cr(" RSet is empty"); } else { hrrs->print(); } tty->print_cr("----------"); return false; } PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { tty->cr(); tty->print_cr("========================================"); tty->print_cr("%s", msg); tty->cr(); } ~PrintRSetsClosure() { tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); tty->print_cr("========================================"); 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 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); size_t eden_capacity_bytes = (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; VirtualSpaceSummary heap_summary = create_heap_space_summary(); return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes, survivor_used_bytes, num_regions()); } G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), stats->unused(), stats->used(), stats->region_end_waste(), stats->regions_filled(), stats->direct_allocated(), stats->failure_used(), stats->failure_waste()); } void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { const G1HeapSummary& heap_summary = create_g1_heap_summary(); gc_tracer->report_gc_heap_summary(when, heap_summary); const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); gc_tracer->report_metaspace_summary(when, metaspace_summary); } 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"); double start = os::elapsedTime(); // Fill TLAB's and such accumulate_statistics_all_tlabs(); ensure_parsability(true); g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); } void G1CollectedHeap::gc_epilogue(bool full) { // we are at the end of the GC. Total collections has already been increased. g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); // FIXME: what is this about? // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" // is set. #if defined(COMPILER2) || INCLUDE_JVMCI assert(DerivedPointerTable::is_empty(), "derived pointer present"); #endif // always_do_update_barrier = true; double start = os::elapsedTime(); resize_all_tlabs(); g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 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(); 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(); return buffer_size * buffer_num + extra_cards; } 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 humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const { assert(region->is_starts_humongous(), "Must start a humongous object"); oop obj = oop(region->bottom()); // Dead objects cannot be eager reclaim candidates. Due to class // unloading it is unsafe to query their classes so we return early. if (heap->is_obj_dead(obj, region)) { return false; } // 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 obj->is_typeArray() && 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->is_in_closed_subset(bs->addr_for(card_ptr))) { if (*card_ptr != CardTableModRefBS::dirty_card_val()) { *card_ptr = CardTableModRefBS::dirty_card_val(); _dcq.enqueue(card_ptr); } } } assert(hrrs.n_yielded() == r->rem_set()->occupied(), "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", hrrs.n_yielded(), r->rem_set()->occupied()); 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(); } class VerifyRegionRemSetClosure : public HeapRegionClosure { public: bool doHeapRegion(HeapRegion* hr) { if (!hr->is_archive() && !hr->is_continues_humongous()) { hr->verify_rem_set(); } return false; } }; uint G1CollectedHeap::num_task_queues() const { return _task_queues->size(); } #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() const { if (!log_is_enabled(Trace, gc, task, stats)) { return; } Log(gc, task, stats) log; ResourceMark rm; outputStream* st = log.trace_stream(); print_taskqueue_stats_hdr(st); TaskQueueStats totals; const uint n = num_task_queues(); 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 = num_task_queues(); for (uint i = 0; i < n; ++i) { task_queue(i)->stats.reset(); } } #endif // TASKQUEUE_STATS void G1CollectedHeap::wait_for_root_region_scanning() { 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); } class G1PrintCollectionSetClosure : public HeapRegionClosure { private: G1HRPrinter* _hr_printer; public: G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } virtual bool doHeapRegion(HeapRegion* r) { _hr_printer->cset(r); return false; } }; void G1CollectedHeap::start_new_collection_set() { collection_set()->start_incremental_building(); clear_cset_fast_test(); guarantee(_eden.length() == 0, "eden should have been cleared"); g1_policy()->transfer_survivors_to_cset(survivor()); } 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 (GCLocker::check_active_before_gc()) { return false; } _gc_timer_stw->register_gc_start(); GCIdMark gc_id_mark; _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); SvcGCMarker sgcm(SvcGCMarker::MINOR); ResourceMark rm; g1_policy()->note_gc_start(); wait_for_root_region_scanning(); print_heap_before_gc(); print_heap_regions(); trace_heap_before_gc(_gc_tracer_stw); _verifier->verify_region_sets_optional(); _verifier->verify_dirty_young_regions(); // We should not be doing initial mark unless the conc mark thread is running if (!_cmThread->should_terminate()) { // 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(!collector_state()->during_initial_mark_pause() || collector_state()->gcs_are_young(), "sanity"); // We also do not allow mixed GCs during marking. assert(!collector_state()->mark_in_progress() || collector_state()->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 = collector_state()->during_initial_mark_pause(); // Inner scope for scope based logging, timers, and stats collection { EvacuationInfo evacuation_info; if (collector_state()->during_initial_mark_pause()) { // We are about to start a marking cycle, so we increment the // full collection counter. increment_old_marking_cycles_started(); _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); } _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); GCTraceCPUTime tcpu; FormatBuffer<> gc_string("Pause "); if (collector_state()->during_initial_mark_pause()) { gc_string.append("Initial Mark"); } else if (collector_state()->gcs_are_young()) { gc_string.append("Young"); } else { gc_string.append("Mixed"); } GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), workers()->active_workers(), Threads::number_of_non_daemon_threads()); workers()->update_active_workers(active_workers); log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 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(); } G1HeapTransition heap_transition(this); size_t heap_used_bytes_before_gc = used(); // 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(); if (VerifyRememberedSets) { log_info(gc, verify)("[Verifying RemSets before GC]"); VerifyRegionRemSetClosure v_cl; heap_region_iterate(&v_cl); } _verifier->verify_before_gc(); _verifier->check_bitmaps("GC Start"); #if defined(COMPILER2) || INCLUDE_JVMCI DerivedPointerTable::clear(); #endif // 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 if (g1_policy()->should_process_references()) { ref_processor_stw()->enable_discovery(); } else { ref_processor_stw()->disable_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(); // 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(); g1_policy()->record_collection_pause_start(sample_start_time_sec); if (collector_state()->during_initial_mark_pause()) { concurrent_mark()->checkpointRootsInitialPre(); } g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); evacuation_info.set_collectionset_regions(collection_set()->region_length()); // Make sure the remembered sets are up to date. This needs to be // done before register_humongous_regions_with_cset(), because the // remembered sets are used there to choose eager reclaim candidates. // If the remembered sets are not up to date we might miss some // entries that need to be handled. g1_rem_set()->cleanupHRRS(); register_humongous_regions_with_cset(); assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); // We call this after finalize_cset() to // ensure that the CSet has been finalized. _cm->verify_no_cset_oops(); if (_hr_printer.is_active()) { G1PrintCollectionSetClosure cl(&_hr_printer); _collection_set.iterate(&cl); } // Initialize the GC alloc regions. _allocator->init_gc_alloc_regions(evacuation_info); G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); pre_evacuate_collection_set(); // Actually do the work... evacuate_collection_set(evacuation_info, &per_thread_states); post_evacuate_collection_set(evacuation_info, &per_thread_states); const size_t* surviving_young_words = per_thread_states.surviving_young_words(); free_collection_set(&_collection_set, evacuation_info, surviving_young_words); eagerly_reclaim_humongous_regions(); record_obj_copy_mem_stats(); _survivor_evac_stats.adjust_desired_plab_sz(); _old_evac_stats.adjust_desired_plab_sz(); double start = os::elapsedTime(); start_new_collection_set(); g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); if (evacuation_failed()) { set_used(recalculate_used()); if (_archive_allocator != NULL) { _archive_allocator->clear_used(); } for (uint i = 0; i < ParallelGCThreads; 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. increase_used(g1_policy()->bytes_copied_during_gc()); } if (collector_state()->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(); collector_state()->set_mark_in_progress(true); // 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(); _allocator->init_mutator_alloc_region(); { size_t expand_bytes = _heap_sizing_policy->expansion_amount(); if (expand_bytes > 0) { size_t bytes_before = capacity(); // No need for an ergo logging here, // expansion_amount() does this when it returns a value > 0. double expand_ms; if (!expand(expand_bytes, _workers, &expand_ms)) { // We failed to expand the heap. Cannot do anything about it. } g1_policy()->phase_times()->record_expand_heap_time(expand_ms); } } // 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(); // 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; size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); MemoryService::track_memory_usage(); if (VerifyRememberedSets) { log_info(gc, verify)("[Verifying RemSets after GC]"); VerifyRegionRemSetClosure v_cl; heap_region_iterate(&v_cl); } _verifier->verify_after_gc(); _verifier->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. } #ifdef TRACESPINNING ParallelTaskTerminator::print_termination_counts(); #endif gc_epilogue(false); } // Print the remainder of the GC log output. if (evacuation_failed()) { log_info(gc)("To-space exhausted"); } g1_policy()->print_phases(); heap_transition.print(); // 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(); _verifier->verify_region_sets_optional(); TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); print_heap_after_gc(); print_heap_regions(); 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::remove_self_forwarding_pointers() { G1ParRemoveSelfForwardPtrsTask rsfp_task; workers()->run_task(&rsfp_task); } void G1CollectedHeap::restore_after_evac_failure() { double remove_self_forwards_start = os::elapsedTime(); remove_self_forwarding_pointers(); SharedRestorePreservedMarksTaskExecutor task_executor(workers()); _preserved_marks_set.restore(&task_executor); g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); } void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { if (!_evacuation_failed) { _evacuation_failed = true; } _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); } bool G1ParEvacuateFollowersClosure::offer_termination() { G1ParScanThreadState* const pss = par_scan_state(); start_term_time(); const bool res = terminator()->offer_termination(); 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 G1ParTask : public AbstractGangTask { protected: G1CollectedHeap* _g1h; G1ParScanThreadStateSet* _pss; RefToScanQueueSet* _queues; G1RootProcessor* _root_processor; ParallelTaskTerminator _terminator; uint _n_workers; public: G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) : AbstractGangTask("G1 collection"), _g1h(g1h), _pss(per_thread_states), _queues(task_queues), _root_processor(root_processor), _terminator(n_workers, _queues), _n_workers(n_workers) {} void work(uint worker_id) { if (worker_id >= _n_workers) return; // no work needed this round double start_sec = os::elapsedTime(); _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); { ResourceMark rm; HandleMark hm; ReferenceProcessor* rp = _g1h->ref_processor_stw(); G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); pss->set_ref_processor(rp); double start_strong_roots_sec = os::elapsedTime(); _root_processor->evacuate_roots(pss->closures(), worker_id); // We pass a weak code blobs closure to the remembered set scanning because we want to avoid // treating the nmethods visited to act as roots for concurrent marking. // We only want to make sure that the oops in the nmethods are adjusted with regard to the // objects copied by the current evacuation. _g1h->g1_rem_set()->oops_into_collection_set_do(pss, pss->closures()->weak_codeblobs(), worker_id); double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; double term_sec = 0.0; size_t evac_term_attempts = 0; { double start = os::elapsedTime(); G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); evac.do_void(); evac_term_attempts = evac.term_attempts(); term_sec = evac.term_time(); double elapsed_sec = os::elapsedTime() - start; _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, evac_term_attempts); } assert(pss->queue_is_empty(), "should be empty"); if (log_is_enabled(Debug, gc, task, stats)) { MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); size_t lab_waste; size_t lab_undo_waste; pss->waste(lab_waste, lab_undo_waste); _g1h->print_termination_stats(worker_id, (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ strong_roots_sec * 1000.0, /* strong roots time */ term_sec * 1000.0, /* evac term time */ evac_term_attempts, /* evac term attempts */ lab_waste, /* alloc buffer waste */ lab_undo_waste /* undo waste */ ); } // 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()); } }; void G1CollectedHeap::print_termination_stats_hdr() { log_debug(gc, task, stats)("GC Termination Stats"); log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); } void G1CollectedHeap::print_termination_stats(uint worker_id, double elapsed_ms, double strong_roots_ms, double term_ms, size_t term_attempts, size_t alloc_buffer_waste, size_t undo_waste) const { log_debug(gc, task, stats) ("%3d %9.2f %9.2f %6.2f " "%9.2f %6.2f " SIZE_FORMAT_W(8) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, term_ms, term_ms * 100 / elapsed_ms, term_attempts, (alloc_buffer_waste + undo_waste) * HeapWordSize / K, alloc_buffer_waste * HeapWordSize / K, undo_waste * HeapWordSize / K); } class G1StringAndSymbolCleaningTask : public AbstractGangTask { private: BoolObjectClosure* _is_alive; G1StringDedupUnlinkOrOopsDoClosure _dedup_closure; 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; bool _process_string_dedup; public: G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) : AbstractGangTask("String/Symbol Unlinking"), _is_alive(is_alive), _dedup_closure(is_alive, NULL, false), _process_strings(process_strings), _strings_processed(0), _strings_removed(0), _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0), _process_string_dedup(process_string_dedup) { _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(); } } ~G1StringAndSymbolCleaningTask() { guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, "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, "claim value %d after unlink less than initial symbol table size %d", SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); log_info(gc, stringtable)( "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); } if (_process_string_dedup) { G1StringDedup::parallel_unlink(&_dedup_closure, worker_id); } } 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. CompiledMethod* _first_nmethod; volatile CompiledMethod* _claimed_nmethod; // The list of nmethods that need to be processed by the second pass. volatile CompiledMethod* _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) { CompiledMethod::increase_unloading_clock(); // Get first alive nmethod CompiledMethodIterator iter = CompiledMethodIterator(); if(iter.next_alive()) { _first_nmethod = iter.method(); } _claimed_nmethod = (volatile CompiledMethod*)_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(CompiledMethod* nm) { CompiledMethod* old; do { old = (CompiledMethod*)_postponed_list; nm->set_unloading_next(old); } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old); } void clean_nmethod(CompiledMethod* 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(CompiledMethod::global_unloading_clock()); } void clean_nmethod_postponed(CompiledMethod* nm) { nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); } static const int MaxClaimNmethods = 16; void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { CompiledMethod* first; CompiledMethodIterator last; do { *num_claimed_nmethods = 0; first = (CompiledMethod*)_claimed_nmethod; last = CompiledMethodIterator(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 ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first); } CompiledMethod* claim_postponed_nmethod() { CompiledMethod* claim; CompiledMethod* next; do { claim = (CompiledMethod*)_postponed_list; if (claim == NULL) { return NULL; } next = claim->unloading_next(); } while ((CompiledMethod*)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; CompiledMethod* 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) { CompiledMethod* 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->is_instance_klass()); // this can be null so don't call InstanceKlass::cast return static_cast(klass); } public: void clean_klass(InstanceKlass* ik) { ik->clean_weak_instanceklass_links(_is_alive); } 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); } } }; class G1ResolvedMethodCleaningTask : public StackObj { BoolObjectClosure* _is_alive; volatile jint _resolved_method_task_claimed; public: G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) : _is_alive(is_alive), _resolved_method_task_claimed(0) {} bool claim_resolved_method_task() { if (_resolved_method_task_claimed) { return false; } return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0; } // These aren't big, one thread can do it all. void work() { if (claim_resolved_method_task()) { ResolvedMethodTable::unlink(_is_alive); } } }; // To minimize the remark pause times, the tasks below are done in parallel. class G1ParallelCleaningTask : public AbstractGangTask { private: G1StringAndSymbolCleaningTask _string_symbol_task; G1CodeCacheUnloadingTask _code_cache_task; G1KlassCleaningTask _klass_cleaning_task; G1ResolvedMethodCleaningTask _resolved_method_cleaning_task; public: // The constructor is run in the VMThread. G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) : AbstractGangTask("Parallel Cleaning"), _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()), _code_cache_task(num_workers, is_alive, unloading_occurred), _klass_cleaning_task(is_alive), _resolved_method_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); // Clean unreferenced things in the ResolvedMethodTable _resolved_method_cleaning_task.work(); // 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::complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred) { uint n_workers = workers()->active_workers(); G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred); workers()->run_task(&g1_unlink_task); } void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) { if (!process_strings && !process_symbols && !process_string_dedup) { // Nothing to clean. return; } G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup); workers()->run_task(&g1_unlink_task); } class G1RedirtyLoggedCardsTask : public AbstractGangTask { private: DirtyCardQueueSet* _queue; G1CollectedHeap* _g1h; public: G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), _queue(queue), _g1h(g1h) { } virtual void work(uint worker_id) { G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); RedirtyLoggedCardTableEntryClosure cl(_g1h); _queue->par_apply_closure_to_all_completed_buffers(&cl); phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); } }; void G1CollectedHeap::redirty_logged_cards() { double redirty_logged_cards_start = os::elapsedTime(); G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); dirty_card_queue_set().reset_for_par_iteration(); workers()->run_task(&redirty_task); 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->is_in_cset(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(), "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), "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; G1ParScanThreadStateSet* _pss; RefToScanQueueSet* _queues; WorkGang* _workers; uint _active_workers; public: G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, WorkGang* workers, RefToScanQueueSet *task_queues, uint n_workers) : _g1h(g1h), _pss(per_thread_states), _queues(task_queues), _workers(workers), _active_workers(n_workers) { g1h->ref_processor_stw()->set_active_mt_degree(n_workers); } // 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; G1ParScanThreadStateSet* _pss; RefToScanQueueSet* _task_queues; ParallelTaskTerminator* _terminator; public: G1STWRefProcTaskProxy(ProcessTask& proc_task, G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, ParallelTaskTerminator* terminator) : AbstractGangTask("Process reference objects in parallel"), _proc_task(proc_task), _g1h(g1h), _pss(per_thread_states), _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 = _pss->state_for_worker(worker_id); pss->set_ref_processor(NULL); // Keep alive closure. G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), 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, _pss, _queues, &terminator); _workers->run_task(&proc_task_proxy); } // 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); _workers->run_task(&enq_task_proxy); } // 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; G1ParScanThreadStateSet* _pss; RefToScanQueueSet* _queues; ParallelTaskTerminator _terminator; uint _n_workers; public: G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) : AbstractGangTask("ParPreserveCMReferents"), _g1h(g1h), _pss(per_thread_states), _queues(task_queues), _terminator(workers, _queues), _n_workers(workers) { g1h->ref_processor_cm()->set_active_mt_degree(workers); } void work(uint worker_id) { G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id); ResourceMark rm; HandleMark hm; G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); pss->set_ref_processor(NULL); assert(pss->queue_is_empty(), "both queue and overflow should be empty"); // Is alive closure G1AlwaysAliveClosure always_alive(_g1h); // Copying keep alive closure. Applied to referent objects that need // to be copied. G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), 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"); } }; void G1CollectedHeap::process_weak_jni_handles() { double ref_proc_start = os::elapsedTime(); G1STWIsAliveClosure is_alive(this); G1KeepAliveClosure keep_alive(this); JNIHandles::weak_oops_do(&is_alive, &keep_alive); double ref_proc_time = os::elapsedTime() - ref_proc_start; g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); } void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) { // 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. double preserve_cm_referents_time = 0.0; // To avoid spawning task when there is no work to do, check that // a concurrent cycle is active and that some references have been // discovered. if (concurrent_mark()->cmThread()->during_cycle() && ref_processor_cm()->has_discovered_references()) { double preserve_cm_referents_start = os::elapsedTime(); uint no_of_gc_workers = workers()->active_workers(); G1ParPreserveCMReferentsTask keep_cm_referents(this, per_thread_states, no_of_gc_workers, _task_queues); workers()->run_task(&keep_cm_referents); preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start; } g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0); } // Weak Reference processing during an evacuation pause (part 1). void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { double ref_proc_start = os::elapsedTime(); ReferenceProcessor* rp = _ref_processor_stw; assert(rp->discovery_enabled(), "should have been enabled"); // 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 = per_thread_states->state_for_worker(0); pss->set_ref_processor(NULL); assert(pss->queue_is_empty(), "pre-condition"); // Keep alive closure. G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), 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); } else { uint no_of_gc_workers = workers()->active_workers(); // Parallel reference processing assert(no_of_gc_workers <= rp->max_num_q(), "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", no_of_gc_workers, rp->max_num_q()); G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, 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->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(G1ParScanThreadStateSet* per_thread_states) { 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 uint n_workers = workers()->active_workers(); assert(n_workers <= rp->max_num_q(), "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", n_workers, rp->max_num_q()); G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_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::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { double merge_pss_time_start = os::elapsedTime(); per_thread_states->flush(); g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); } void G1CollectedHeap::pre_evacuate_collection_set() { _expand_heap_after_alloc_failure = true; _evacuation_failed = false; // Disable the hot card cache. _hot_card_cache->reset_hot_cache_claimed_index(); _hot_card_cache->set_use_cache(false); g1_rem_set()->prepare_for_oops_into_collection_set_do(); _preserved_marks_set.assert_empty(); G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); // InitialMark needs claim bits to keep track of the marked-through CLDs. if (collector_state()->during_initial_mark_pause()) { double start_clear_claimed_marks = os::elapsedTime(); ClassLoaderDataGraph::clear_claimed_marks(); double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); } } void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { // Should G1EvacuationFailureALot be in effect for this GC? NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); double start_par_time_sec = os::elapsedTime(); double end_par_time_sec; { const uint n_workers = workers()->active_workers(); G1RootProcessor root_processor(this, n_workers); G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); print_termination_stats_hdr(); 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. } 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); } void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { // 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. if (g1_policy()->should_process_references()) { preserve_cm_referents(per_thread_states); process_discovered_references(per_thread_states); } else { ref_processor_stw()->verify_no_references_recorded(); process_weak_jni_handles(); } 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, g1_policy()->phase_times()); double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); } g1_rem_set()->cleanup_after_oops_into_collection_set_do(); if (evacuation_failed()) { restore_after_evac_failure(); // Reset the G1EvacuationFailureALot counters and flags // Note: the values are reset only when an actual // evacuation failure occurs. NOT_PRODUCT(reset_evacuation_should_fail();) } _preserved_marks_set.assert_empty(); // 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. if (g1_policy()->should_process_references()) { enqueue_discovered_references(per_thread_states); } else { g1_policy()->phase_times()->record_ref_enq_time(0); } _allocator->release_gc_alloc_regions(evacuation_info); merge_per_thread_state_info(per_thread_states); // 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(); redirty_logged_cards(); #if defined(COMPILER2) || INCLUDE_JVMCI double start = os::elapsedTime(); DerivedPointerTable::update_pointers(); g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); #endif g1_policy()->print_age_table(); } void G1CollectedHeap::record_obj_copy_mem_stats() { g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), create_g1_evac_summary(&_old_evac_stats)); } void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list, bool skip_remset, bool skip_hot_card_cache, 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 (!skip_hot_card_cache && !hr->is_young()) { _hot_card_cache->reset_card_counts(hr); } hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); free_list->add_ordered(hr); } void G1CollectedHeap::free_humongous_region(HeapRegion* hr, FreeRegionList* free_list, bool skip_remset) { assert(hr->is_humongous(), "this is only for humongous regions"); assert(free_list != NULL, "pre-condition"); hr->clear_humongous(); free_region(hr, free_list, skip_remset); } void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed) { if (old_regions_removed > 0 || humongous_regions_removed > 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) { decrease_used(bytes); } class G1ParScrubRemSetTask: public AbstractGangTask { protected: G1RemSet* _g1rs; HeapRegionClaimer _hrclaimer; public: G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) : AbstractGangTask("G1 ScrubRS"), _g1rs(g1_rs), _hrclaimer(num_workers) { } void work(uint worker_id) { _g1rs->scrub(worker_id, &_hrclaimer); } }; void G1CollectedHeap::scrub_rem_set() { uint num_workers = workers()->active_workers(); G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers); workers()->run_task(&g1_par_scrub_rs_task); } class G1FreeCollectionSetTask : public AbstractGangTask { private: // Closure applied to all regions in the collection set to do work that needs to // be done serially in a single thread. class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { private: EvacuationInfo* _evacuation_info; const size_t* _surviving_young_words; // Bytes used in successfully evacuated regions before the evacuation. size_t _before_used_bytes; // Bytes used in unsucessfully evacuated regions before the evacuation size_t _after_used_bytes; size_t _bytes_allocated_in_old_since_last_gc; size_t _failure_used_words; size_t _failure_waste_words; FreeRegionList _local_free_list; public: G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : HeapRegionClosure(), _evacuation_info(evacuation_info), _surviving_young_words(surviving_young_words), _before_used_bytes(0), _after_used_bytes(0), _bytes_allocated_in_old_since_last_gc(0), _failure_used_words(0), _failure_waste_words(0), _local_free_list("Local Region List for CSet Freeing") { } virtual bool doHeapRegion(HeapRegion* r) { G1CollectedHeap* g1h = G1CollectedHeap::heap(); assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); g1h->clear_in_cset(r); if (r->is_young()) { assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), "Young index %d is wrong for region %u of type %s with %u young regions", r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), g1h->collection_set()->young_region_length()); size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; r->record_surv_words_in_group(words_survived); } if (!r->evacuation_failed()) { assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); _before_used_bytes += r->used(); g1h->free_region(r, &_local_free_list, true, /* skip_remset */ true, /* skip_hot_card_cache */ true /* locked */); } else { r->uninstall_surv_rate_group(); r->set_young_index_in_cset(-1); r->set_evacuation_failed(false); // When moving a young gen region to old gen, we "allocate" that whole region // there. This is in addition to any already evacuated objects. Notify the // policy about that. // Old gen regions do not cause an additional allocation: both the objects // still in the region and the ones already moved are accounted for elsewhere. if (r->is_young()) { _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; } // The region is now considered to be old. r->set_old(); // Do some allocation statistics accounting. Regions that failed evacuation // are always made old, so there is no need to update anything in the young // gen statistics, but we need to update old gen statistics. size_t used_words = r->marked_bytes() / HeapWordSize; _failure_used_words += used_words; _failure_waste_words += HeapRegion::GrainWords - used_words; g1h->old_set_add(r); _after_used_bytes += r->used(); } return false; } void complete_work() { G1CollectedHeap* g1h = G1CollectedHeap::heap(); _evacuation_info->set_regions_freed(_local_free_list.length()); _evacuation_info->increment_collectionset_used_after(_after_used_bytes); g1h->prepend_to_freelist(&_local_free_list); g1h->decrement_summary_bytes(_before_used_bytes); G1Policy* policy = g1h->g1_policy(); policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); } }; G1CollectionSet* _collection_set; G1SerialFreeCollectionSetClosure _cl; const size_t* _surviving_young_words; size_t _rs_lengths; volatile jint _serial_work_claim; struct WorkItem { uint region_idx; bool is_young; bool evacuation_failed; WorkItem(HeapRegion* r) { region_idx = r->hrm_index(); is_young = r->is_young(); evacuation_failed = r->evacuation_failed(); } }; volatile size_t _parallel_work_claim; size_t _num_work_items; WorkItem* _work_items; void do_serial_work() { // Need to grab the lock to be allowed to modify the old region list. MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); _collection_set->iterate(&_cl); } void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { G1CollectedHeap* g1h = G1CollectedHeap::heap(); HeapRegion* r = g1h->region_at(region_idx); assert(!g1h->is_on_master_free_list(r), "sanity"); Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); if (!is_young) { g1h->_hot_card_cache->reset_card_counts(r); } if (!evacuation_failed) { r->rem_set()->clear_locked(); } } class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { private: size_t _cur_idx; WorkItem* _work_items; public: G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } virtual bool doHeapRegion(HeapRegion* r) { _work_items[_cur_idx++] = WorkItem(r); return false; } }; void prepare_work() { G1PrepareFreeCollectionSetClosure cl(_work_items); _collection_set->iterate(&cl); } void complete_work() { _cl.complete_work(); G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); policy->record_max_rs_lengths(_rs_lengths); policy->cset_regions_freed(); } public: G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : AbstractGangTask("G1 Free Collection Set"), _cl(evacuation_info, surviving_young_words), _collection_set(collection_set), _surviving_young_words(surviving_young_words), _serial_work_claim(0), _rs_lengths(0), _parallel_work_claim(0), _num_work_items(collection_set->region_length()), _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { prepare_work(); } ~G1FreeCollectionSetTask() { complete_work(); FREE_C_HEAP_ARRAY(WorkItem, _work_items); } // Chunk size for work distribution. The chosen value has been determined experimentally // to be a good tradeoff between overhead and achievable parallelism. static uint chunk_size() { return 32; } virtual void work(uint worker_id) { G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); // Claim serial work. if (_serial_work_claim == 0) { jint value = Atomic::add(1, &_serial_work_claim) - 1; if (value == 0) { double serial_time = os::elapsedTime(); do_serial_work(); timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); } } // Start parallel work. double young_time = 0.0; bool has_young_time = false; double non_young_time = 0.0; bool has_non_young_time = false; while (true) { size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); size_t cur = end - chunk_size(); if (cur >= _num_work_items) { break; } double start_time = os::elapsedTime(); end = MIN2(end, _num_work_items); for (; cur < end; cur++) { bool is_young = _work_items[cur].is_young; do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); double end_time = os::elapsedTime(); double time_taken = end_time - start_time; if (is_young) { young_time += time_taken; has_young_time = true; } else { non_young_time += time_taken; has_non_young_time = true; } start_time = end_time; } } if (has_young_time) { timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); } if (has_non_young_time) { timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time); } } }; void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { _eden.clear(); double free_cset_start_time = os::elapsedTime(); { uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); uint const num_workers = MIN2(workers()->active_workers(), num_chunks); G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", cl.name(), num_workers, _collection_set.region_length()); workers()->run_task(&cl, num_workers); } g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); collection_set->clear(); } class G1FreeHumongousRegionClosure : public HeapRegionClosure { private: FreeRegionList* _free_region_list; HeapRegionSet* _proxy_set; uint _humongous_objects_reclaimed; uint _humongous_regions_reclaimed; size_t _freed_bytes; public: G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { } virtual bool doHeapRegion(HeapRegion* r) { if (!r->is_starts_humongous()) { return false; } G1CollectedHeap* g1h = G1CollectedHeap::heap(); oop obj = (oop)r->bottom(); G1CMBitMap* 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()) { log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " 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->rem_set()->occupied(), r->rem_set()->strong_code_roots_list_length(), next_bitmap->is_marked(r->bottom()), g1h->is_humongous_reclaim_candidate(region_idx), obj->is_typeArray() ); return false; } guarantee(obj->is_typeArray(), "Only eagerly reclaiming type arrays is supported, but the object " PTR_FORMAT " is not.", p2i(r->bottom())); log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " 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->rem_set()->occupied(), r->rem_set()->strong_code_roots_list_length(), next_bitmap->is_marked(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->is_marked(r->bottom())) { next_bitmap->clear(r->bottom()); } _humongous_objects_reclaimed++; do { HeapRegion* next = g1h->next_region_in_humongous(r); _freed_bytes += r->used(); r->set_containing_set(NULL); _humongous_regions_reclaimed++; g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ ); r = next; } while (r != NULL); return false; } uint humongous_objects_reclaimed() { return _humongous_objects_reclaimed; } uint humongous_regions_reclaimed() { return _humongous_regions_reclaimed; } size_t bytes_freed() const { return _freed_bytes; } }; void G1CollectedHeap::eagerly_reclaim_humongous_regions() { assert_at_safepoint(true); if (!G1EagerReclaimHumongousObjects || (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 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); remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 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_objects_reclaimed()); } class G1AbandonCollectionSetClosure : public HeapRegionClosure { public: virtual bool doHeapRegion(HeapRegion* r) { assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); G1CollectedHeap::heap()->clear_in_cset(r); r->set_young_index_in_cset(-1); return false; } }; void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { G1AbandonCollectionSetClosure cl; collection_set->iterate(&cl); collection_set->clear(); collection_set->stop_incremental_building(); } void G1CollectedHeap::set_free_regions_coming() { log_develop_trace(gc, freelist)("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(); } log_develop_trace(gc, freelist)("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; } log_develop_trace(gc, freelist)("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); } } log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions"); } bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { return _allocator->is_retained_old_region(hr); } void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { _eden.add(hr); _g1_policy->set_region_eden(hr); } #ifdef ASSERT class NoYoungRegionsClosure: public HeapRegionClosure { private: bool _success; public: NoYoungRegionsClosure() : _success(true) { } bool doHeapRegion(HeapRegion* r) { if (r->is_young()) { log_error(gc, verify)("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 ret = (young_regions_count() == 0); NoYoungRegionsClosure closure; heap_region_iterate(&closure); ret = ret && closure.success(); return ret; } #endif // ASSERT 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 if(r->is_young()) { r->uninstall_surv_rate_group(); } else { // We ignore free regions, we'll empty the free list afterwards. // We ignore humongous regions, we're not tearing down the // humongous regions set. assert(r->is_free() || 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(); } void G1CollectedHeap::increase_used(size_t bytes) { _summary_bytes_used += bytes; } void G1CollectedHeap::decrease_used(size_t bytes) { assert(_summary_bytes_used >= bytes, "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, _summary_bytes_used, bytes); _summary_bytes_used -= bytes; } void G1CollectedHeap::set_used(size_t bytes) { _summary_bytes_used = bytes; } 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_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) { if (r->is_humongous()) { // We ignore humongous regions. We left the humongous set unchanged. } else { assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); // We now consider all regions old, so register as such. Leave // archive regions set that way, however, while still adding // them to the old set. if (!r->is_archive()) { 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) { _eden.clear(); _survivor.clear(); } RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); heap_region_iterate(&cl); if (!free_list_only) { set_used(cl.total_used()); if (_archive_allocator != NULL) { _archive_allocator->clear_used(); } } assert(used_unlocked() == recalculate_used(), "inconsistent used_unlocked(), " "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, used_unlocked(), recalculate_used()); } 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 */); bool should_allocate = g1_policy()->should_allocate_mutator_region(); if (force || should_allocate) { 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, !should_allocate); _verifier->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"); collection_set()->add_eden_region(alloc_region); 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(); } // Methods for the GC alloc regions bool G1CollectedHeap::has_more_regions(InCSetState dest) { if (dest.is_old()) { return true; } else { return survivor_regions_count() < g1_policy()->max_survivor_regions(); } } HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { assert(FreeList_lock->owned_by_self(), "pre-condition"); if (!has_more_regions(dest)) { return NULL; } 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(); _survivor.add(new_alloc_region); _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); } else { new_alloc_region->set_old(); _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); } _hr_printer.alloc(new_alloc_region); bool during_im = collector_state()->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 = collector_state()->during_initial_mark_pause(); alloc_region->note_end_of_copying(during_im); g1_policy()->record_bytes_copied_during_gc(allocated_bytes); if (dest.is_old()) { _old_set.add(alloc_region); } _hr_printer.retire(alloc_region); } HeapRegion* G1CollectedHeap::alloc_highest_free_region() { bool expanded = false; uint index = _hrm.find_highest_free(&expanded); if (index != G1_NO_HRM_INDEX) { if (expanded) { log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", HeapRegion::GrainWords * HeapWordSize); } _hrm.allocate_free_regions_starting_at(index, 1); return region_at(index); } return NULL; } // 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(), "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(), "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); }