/* * Copyright (c) 2014, 2020, 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 "gc/g1/g1Allocator.inline.hpp" #include "gc/g1/g1CollectedHeap.inline.hpp" #include "gc/g1/g1CollectionSet.hpp" #include "gc/g1/g1OopClosures.inline.hpp" #include "gc/g1/g1ParScanThreadState.inline.hpp" #include "gc/g1/g1RootClosures.hpp" #include "gc/g1/g1StringDedup.hpp" #include "gc/g1/g1Trace.hpp" #include "gc/shared/taskqueue.inline.hpp" #include "memory/allocation.inline.hpp" #include "oops/access.inline.hpp" #include "oops/oop.inline.hpp" #include "runtime/prefetch.inline.hpp" G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, G1RedirtyCardsQueueSet* rdcqs, uint worker_id, size_t young_cset_length, size_t optional_cset_length) : _g1h(g1h), _task_queue(g1h->task_queue(worker_id)), _rdcq(rdcqs), _ct(g1h->card_table()), _closures(NULL), _plab_allocator(NULL), _age_table(false), _tenuring_threshold(g1h->policy()->tenuring_threshold()), _scanner(g1h, this), _worker_id(worker_id), _last_enqueued_card(SIZE_MAX), _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1), _stack_trim_lower_threshold(GCDrainStackTargetSize), _trim_ticks(), _surviving_young_words_base(NULL), _surviving_young_words(NULL), _surviving_words_length(young_cset_length + 1), _old_gen_is_full(false), _num_optional_regions(optional_cset_length), _numa(g1h->numa()), _obj_alloc_stat(NULL) { // We allocate number of young gen regions in the collection set plus one // entries, since entry 0 keeps track of surviving bytes for non-young regions. // We also add a few elements at the beginning and at the end in // an attempt to eliminate cache contention const size_t padding_elem_num = (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)); size_t array_length = padding_elem_num + _surviving_words_length + padding_elem_num; _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); _surviving_young_words = _surviving_young_words_base + padding_elem_num; memset(_surviving_young_words, 0, _surviving_words_length * sizeof(size_t)); _plab_allocator = new G1PLABAllocator(_g1h->allocator()); // The dest for Young is used when the objects are aged enough to // need to be moved to the next space. _dest[G1HeapRegionAttr::Young] = G1HeapRegionAttr::Old; _dest[G1HeapRegionAttr::Old] = G1HeapRegionAttr::Old; _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h); _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions]; initialize_numa_stats(); } size_t G1ParScanThreadState::flush(size_t* surviving_young_words) { _rdcq.flush(); flush_numa_stats(); // Update allocation statistics. _plab_allocator->flush_and_retire_stats(); _g1h->policy()->record_age_table(&_age_table); size_t sum = 0; for (uint i = 0; i < _surviving_words_length; i++) { surviving_young_words[i] += _surviving_young_words[i]; sum += _surviving_young_words[i]; } return sum; } G1ParScanThreadState::~G1ParScanThreadState() { delete _plab_allocator; delete _closures; FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); delete[] _oops_into_optional_regions; FREE_C_HEAP_ARRAY(size_t, _obj_alloc_stat); } size_t G1ParScanThreadState::lab_waste_words() const { return _plab_allocator->waste(); } size_t G1ParScanThreadState::lab_undo_waste_words() const { return _plab_allocator->undo_waste(); } #ifdef ASSERT void G1ParScanThreadState::verify_task(narrowOop* task) const { assert(task != NULL, "invariant"); assert(UseCompressedOops, "sanity"); oop p = RawAccess<>::oop_load(task); assert(_g1h->is_in_g1_reserved(p), "task=" PTR_FORMAT " p=" PTR_FORMAT, p2i(task), p2i(p)); } void G1ParScanThreadState::verify_task(oop* task) const { assert(task != NULL, "invariant"); oop p = RawAccess<>::oop_load(task); assert(_g1h->is_in_g1_reserved(p), "task=" PTR_FORMAT " p=" PTR_FORMAT, p2i(task), p2i(p)); } void G1ParScanThreadState::verify_task(PartialArrayScanTask task) const { // Must be in the collection set--it's already been copied. oop p = task.to_source_array(); assert(_g1h->is_in_cset(p), "p=" PTR_FORMAT, p2i(p)); } void G1ParScanThreadState::verify_task(ScannerTask task) const { if (task.is_narrow_oop_ptr()) { verify_task(task.to_narrow_oop_ptr()); } else if (task.is_oop_ptr()) { verify_task(task.to_oop_ptr()); } else if (task.is_partial_array_task()) { verify_task(task.to_partial_array_task()); } else { ShouldNotReachHere(); } } #endif // ASSERT template void G1ParScanThreadState::do_oop_evac(T* p) { // Reference should not be NULL here as such are never pushed to the task queue. oop obj = RawAccess::oop_load(p); // Although we never intentionally push references outside of the collection // set, due to (benign) races in the claim mechanism during RSet scanning more // than one thread might claim the same card. So the same card may be // processed multiple times, and so we might get references into old gen here. // So we need to redo this check. const G1HeapRegionAttr region_attr = _g1h->region_attr(obj); // References pushed onto the work stack should never point to a humongous region // as they are not added to the collection set due to above precondition. assert(!region_attr.is_humongous(), "Obj " PTR_FORMAT " should not refer to humongous region %u from " PTR_FORMAT, p2i(obj), _g1h->addr_to_region(cast_from_oop(obj)), p2i(p)); if (!region_attr.is_in_cset()) { // In this case somebody else already did all the work. return; } markWord m = obj->mark_raw(); if (m.is_marked()) { obj = (oop) m.decode_pointer(); } else { obj = do_copy_to_survivor_space(region_attr, obj, m); } RawAccess::oop_store(p, obj); assert(obj != NULL, "Must be"); if (HeapRegion::is_in_same_region(p, obj)) { return; } HeapRegion* from = _g1h->heap_region_containing(p); if (!from->is_young()) { enqueue_card_if_tracked(_g1h->region_attr(obj), p, obj); } } void G1ParScanThreadState::do_partial_array(PartialArrayScanTask task) { oop from_obj = task.to_source_array(); assert(_g1h->is_in_reserved(from_obj), "must be in heap."); assert(from_obj->is_objArray(), "must be obj array"); objArrayOop from_obj_array = objArrayOop(from_obj); // The from-space object contains the real length. int length = from_obj_array->length(); assert(from_obj->is_forwarded(), "must be forwarded"); oop to_obj = from_obj->forwardee(); assert(from_obj != to_obj, "should not be chunking self-forwarded objects"); objArrayOop to_obj_array = objArrayOop(to_obj); // We keep track of the next start index in the length field of the // to-space object. int next_index = to_obj_array->length(); assert(0 <= next_index && next_index < length, "invariant, next index: %d, length: %d", next_index, length); int start = next_index; int end = length; int remainder = end - start; // We'll try not to push a range that's smaller than ParGCArrayScanChunk. if (remainder > 2 * ParGCArrayScanChunk) { end = start + ParGCArrayScanChunk; to_obj_array->set_length(end); // Push the remainder before we process the range in case another // worker has run out of things to do and can steal it. push_on_queue(ScannerTask(PartialArrayScanTask(from_obj))); } else { assert(length == end, "sanity"); // We'll process the final range for this object. Restore the length // so that the heap remains parsable in case of evacuation failure. to_obj_array->set_length(end); } HeapRegion* hr = _g1h->heap_region_containing(to_obj); G1ScanInYoungSetter x(&_scanner, hr->is_young()); // Process indexes [start,end). It will also process the header // along with the first chunk (i.e., the chunk with start == 0). // Note that at this point the length field of to_obj_array is not // correct given that we are using it to keep track of the next // start index. oop_iterate_range() (thankfully!) ignores the length // field and only relies on the start / end parameters. It does // however return the size of the object which will be incorrect. So // we have to ignore it even if we wanted to use it. to_obj_array->oop_iterate_range(&_scanner, start, end); } void G1ParScanThreadState::dispatch_task(ScannerTask task) { verify_task(task); if (task.is_narrow_oop_ptr()) { do_oop_evac(task.to_narrow_oop_ptr()); } else if (task.is_oop_ptr()) { do_oop_evac(task.to_oop_ptr()); } else { do_partial_array(task.to_partial_array_task()); } } // Process tasks until overflow queue is empty and local queue // contains no more than threshold entries. NOINLINE to prevent // inlining into steal_and_trim_queue. ATTRIBUTE_FLATTEN NOINLINE void G1ParScanThreadState::trim_queue_to_threshold(uint threshold) { ScannerTask task; do { while (_task_queue->pop_overflow(task)) { if (!_task_queue->try_push_to_taskqueue(task)) { dispatch_task(task); } } while (_task_queue->pop_local(task, threshold)) { dispatch_task(task); } } while (!_task_queue->overflow_empty()); } ATTRIBUTE_FLATTEN void G1ParScanThreadState::steal_and_trim_queue(G1ScannerTasksQueueSet* task_queues) { ScannerTask stolen_task; while (task_queues->steal(_worker_id, stolen_task)) { dispatch_task(stolen_task); // Processing stolen task may have added tasks to our queue. trim_queue(); } } HeapWord* G1ParScanThreadState::allocate_in_next_plab(G1HeapRegionAttr* dest, size_t word_sz, bool previous_plab_refill_failed, uint node_index) { assert(dest->is_in_cset_or_humongous(), "Unexpected dest: %s region attr", dest->get_type_str()); // Right now we only have two types of regions (young / old) so // let's keep the logic here simple. We can generalize it when necessary. if (dest->is_young()) { bool plab_refill_in_old_failed = false; HeapWord* const obj_ptr = _plab_allocator->allocate(G1HeapRegionAttr::Old, word_sz, &plab_refill_in_old_failed, node_index); // Make sure that we won't attempt to copy any other objects out // of a survivor region (given that apparently we cannot allocate // any new ones) to avoid coming into this slow path again and again. // Only consider failed PLAB refill here: failed inline allocations are // typically large, so not indicative of remaining space. if (previous_plab_refill_failed) { _tenuring_threshold = 0; } if (obj_ptr != NULL) { dest->set_old(); } else { // We just failed to allocate in old gen. The same idea as explained above // for making survivor gen unavailable for allocation applies for old gen. _old_gen_is_full = plab_refill_in_old_failed; } return obj_ptr; } else { _old_gen_is_full = previous_plab_refill_failed; assert(dest->is_old(), "Unexpected dest region attr: %s", dest->get_type_str()); // no other space to try. return NULL; } } G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markWord const m, uint& age) { if (region_attr.is_young()) { age = !m.has_displaced_mark_helper() ? m.age() : m.displaced_mark_helper().age(); if (age < _tenuring_threshold) { return region_attr; } } return dest(region_attr); } void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr, oop const old, size_t word_sz, uint age, HeapWord * const obj_ptr, uint node_index) const { PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr, node_index); if (alloc_buf->contains(obj_ptr)) { _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age, dest_attr.type() == G1HeapRegionAttr::Old, alloc_buf->word_sz() * HeapWordSize); } else { _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age, dest_attr.type() == G1HeapRegionAttr::Old); } } // Private inline function, for direct internal use and providing the // implementation of the public not-inline function. oop G1ParScanThreadState::do_copy_to_survivor_space(G1HeapRegionAttr const region_attr, oop const old, markWord const old_mark) { const size_t word_sz = old->size(); uint age = 0; G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age); // The second clause is to prevent premature evacuation failure in case there // is still space in survivor, but old gen is full. if (_old_gen_is_full && dest_attr.is_old()) { return handle_evacuation_failure_par(old, old_mark); } HeapRegion* const from_region = _g1h->heap_region_containing(old); uint node_index = from_region->node_index(); HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz, node_index); // PLAB allocations should succeed most of the time, so we'll // normally check against NULL once and that's it. if (obj_ptr == NULL) { bool plab_refill_failed = false; obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_attr, word_sz, &plab_refill_failed, node_index); if (obj_ptr == NULL) { assert(region_attr.is_in_cset(), "Unexpected region attr type: %s", region_attr.get_type_str()); obj_ptr = allocate_in_next_plab(&dest_attr, word_sz, plab_refill_failed, node_index); if (obj_ptr == NULL) { // This will either forward-to-self, or detect that someone else has // installed a forwarding pointer. return handle_evacuation_failure_par(old, old_mark); } } update_numa_stats(node_index); if (_g1h->_gc_tracer_stw->should_report_promotion_events()) { // The events are checked individually as part of the actual commit report_promotion_event(dest_attr, old, word_sz, age, obj_ptr, node_index); } } assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); #ifndef PRODUCT // Should this evacuation fail? if (_g1h->evacuation_should_fail()) { // Doing this after all the allocation attempts also tests the // undo_allocation() method too. _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index); return handle_evacuation_failure_par(old, old_mark); } #endif // !PRODUCT // We're going to allocate linearly, so might as well prefetch ahead. Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); const oop obj = oop(obj_ptr); const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed); if (forward_ptr == NULL) { Copy::aligned_disjoint_words(cast_from_oop(old), obj_ptr, word_sz); const uint young_index = from_region->young_index_in_cset(); assert((from_region->is_young() && young_index > 0) || (!from_region->is_young() && young_index == 0), "invariant" ); if (dest_attr.is_young()) { if (age < markWord::max_age) { age++; } if (old_mark.has_displaced_mark_helper()) { // In this case, we have to install the mark word first, // otherwise obj looks to be forwarded (the old mark word, // which contains the forward pointer, was copied) obj->set_mark_raw(old_mark); markWord new_mark = old_mark.displaced_mark_helper().set_age(age); old_mark.set_displaced_mark_helper(new_mark); } else { obj->set_mark_raw(old_mark.set_age(age)); } _age_table.add(age, word_sz); } else { obj->set_mark_raw(old_mark); } if (G1StringDedup::is_enabled()) { const bool is_from_young = region_attr.is_young(); const bool is_to_young = dest_attr.is_young(); assert(is_from_young == from_region->is_young(), "sanity"); assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(), "sanity"); G1StringDedup::enqueue_from_evacuation(is_from_young, is_to_young, _worker_id, obj); } _surviving_young_words[young_index] += word_sz; if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { // We keep track of the next start index in the length field of // the to-space object. The actual length can be found in the // length field of the from-space object. arrayOop(obj)->set_length(0); do_partial_array(PartialArrayScanTask(old)); } else { G1ScanInYoungSetter x(&_scanner, dest_attr.is_young()); obj->oop_iterate_backwards(&_scanner); } return obj; } else { _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index); return forward_ptr; } } // Public not-inline entry point. ATTRIBUTE_FLATTEN oop G1ParScanThreadState::copy_to_survivor_space(G1HeapRegionAttr region_attr, oop old, markWord old_mark) { return do_copy_to_survivor_space(region_attr, old, old_mark); } G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) { assert(worker_id < _n_workers, "out of bounds access"); if (_states[worker_id] == NULL) { _states[worker_id] = new G1ParScanThreadState(_g1h, _rdcqs, worker_id, _young_cset_length, _optional_cset_length); } return _states[worker_id]; } const size_t* G1ParScanThreadStateSet::surviving_young_words() const { assert(_flushed, "thread local state from the per thread states should have been flushed"); return _surviving_young_words_total; } void G1ParScanThreadStateSet::flush() { assert(!_flushed, "thread local state from the per thread states should be flushed once"); for (uint worker_id = 0; worker_id < _n_workers; ++worker_id) { G1ParScanThreadState* pss = _states[worker_id]; if (pss == NULL) { continue; } G1GCPhaseTimes* p = _g1h->phase_times(); // Need to get the following two before the call to G1ParThreadScanState::flush() // because it resets the PLAB allocator where we get this info from. size_t lab_waste_bytes = pss->lab_waste_words() * HeapWordSize; size_t lab_undo_waste_bytes = pss->lab_undo_waste_words() * HeapWordSize; size_t copied_bytes = pss->flush(_surviving_young_words_total) * HeapWordSize; p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, copied_bytes, G1GCPhaseTimes::MergePSSCopiedBytes); p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, lab_waste_bytes, G1GCPhaseTimes::MergePSSLABWasteBytes); p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, lab_undo_waste_bytes, G1GCPhaseTimes::MergePSSLABUndoWasteBytes); delete pss; _states[worker_id] = NULL; } _flushed = true; } void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) { for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { G1ParScanThreadState* pss = _states[worker_index]; if (pss == NULL) { continue; } size_t used_memory = pss->oops_into_optional_region(hr)->used_memory(); _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanHR, worker_index, used_memory, G1GCPhaseTimes::ScanHRUsedMemory); } } oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markWord m) { assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed); if (forward_ptr == NULL) { // Forward-to-self succeeded. We are the "owner" of the object. HeapRegion* r = _g1h->heap_region_containing(old); if (!r->evacuation_failed()) { r->set_evacuation_failed(true); _g1h->hr_printer()->evac_failure(r); } _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); G1ScanInYoungSetter x(&_scanner, r->is_young()); old->oop_iterate_backwards(&_scanner); return old; } else { // Forward-to-self failed. Either someone else managed to allocate // space for this object (old != forward_ptr) or they beat us in // self-forwarding it (old == forward_ptr). assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr), "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " "should not be in the CSet", p2i(old), p2i(forward_ptr)); return forward_ptr; } } void G1ParScanThreadState::initialize_numa_stats() { if (_numa->is_enabled()) { LogTarget(Info, gc, heap, numa) lt; if (lt.is_enabled()) { uint num_nodes = _numa->num_active_nodes(); // Record only if there are multiple active nodes. _obj_alloc_stat = NEW_C_HEAP_ARRAY(size_t, num_nodes, mtGC); memset(_obj_alloc_stat, 0, sizeof(size_t) * num_nodes); } } } void G1ParScanThreadState::flush_numa_stats() { if (_obj_alloc_stat != NULL) { uint node_index = _numa->index_of_current_thread(); _numa->copy_statistics(G1NUMAStats::LocalObjProcessAtCopyToSurv, node_index, _obj_alloc_stat); } } void G1ParScanThreadState::update_numa_stats(uint node_index) { if (_obj_alloc_stat != NULL) { _obj_alloc_stat[node_index]++; } } G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, G1RedirtyCardsQueueSet* rdcqs, uint n_workers, size_t young_cset_length, size_t optional_cset_length) : _g1h(g1h), _rdcqs(rdcqs), _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)), _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length + 1, mtGC)), _young_cset_length(young_cset_length), _optional_cset_length(optional_cset_length), _n_workers(n_workers), _flushed(false) { for (uint i = 0; i < n_workers; ++i) { _states[i] = NULL; } memset(_surviving_young_words_total, 0, (young_cset_length + 1) * sizeof(size_t)); } G1ParScanThreadStateSet::~G1ParScanThreadStateSet() { assert(_flushed, "thread local state from the per thread states should have been flushed"); FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states); FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total); }