/* * Copyright (c) 2002, 2012, 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/symbolTable.hpp" #include "code/codeCache.hpp" #include "gc_implementation/parallelScavenge/cardTableExtension.hpp" #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" #include "gc_implementation/parallelScavenge/generationSizer.hpp" #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" #include "gc_implementation/parallelScavenge/psParallelCompact.hpp" #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp" #include "gc_implementation/parallelScavenge/psTasks.hpp" #include "gc_implementation/shared/gcHeapSummary.hpp" #include "gc_implementation/shared/gcTimer.hpp" #include "gc_implementation/shared/gcTrace.hpp" #include "gc_implementation/shared/gcTraceTime.hpp" #include "gc_implementation/shared/isGCActiveMark.hpp" #include "gc_implementation/shared/spaceDecorator.hpp" #include "gc_interface/gcCause.hpp" #include "memory/collectorPolicy.hpp" #include "memory/gcLocker.inline.hpp" #include "memory/referencePolicy.hpp" #include "memory/referenceProcessor.hpp" #include "memory/resourceArea.hpp" #include "oops/oop.inline.hpp" #include "oops/oop.psgc.inline.hpp" #include "runtime/biasedLocking.hpp" #include "runtime/fprofiler.hpp" #include "runtime/handles.inline.hpp" #include "runtime/threadCritical.hpp" #include "runtime/vmThread.hpp" #include "runtime/vm_operations.hpp" #include "services/memoryService.hpp" #include "utilities/stack.inline.hpp" HeapWord* PSScavenge::_to_space_top_before_gc = NULL; int PSScavenge::_consecutive_skipped_scavenges = 0; ReferenceProcessor* PSScavenge::_ref_processor = NULL; CardTableExtension* PSScavenge::_card_table = NULL; bool PSScavenge::_survivor_overflow = false; int PSScavenge::_tenuring_threshold = 0; HeapWord* PSScavenge::_young_generation_boundary = NULL; elapsedTimer PSScavenge::_accumulated_time; STWGCTimer PSScavenge::_gc_timer; ParallelScavengeTracer PSScavenge::_gc_tracer; Stack PSScavenge::_preserved_mark_stack; Stack PSScavenge::_preserved_oop_stack; CollectorCounters* PSScavenge::_counters = NULL; // Define before use class PSIsAliveClosure: public BoolObjectClosure { public: void do_object(oop p) { assert(false, "Do not call."); } bool do_object_b(oop p) { return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded(); } }; PSIsAliveClosure PSScavenge::_is_alive_closure; class PSKeepAliveClosure: public OopClosure { protected: MutableSpace* _to_space; PSPromotionManager* _promotion_manager; public: PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); _to_space = heap->young_gen()->to_space(); assert(_promotion_manager != NULL, "Sanity"); } template void do_oop_work(T* p) { assert (!oopDesc::is_null(*p), "expected non-null ref"); assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), "expected an oop while scanning weak refs"); // Weak refs may be visited more than once. if (PSScavenge::should_scavenge(p, _to_space)) { PSScavenge::copy_and_push_safe_barrier(_promotion_manager, p); } } virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } }; class PSEvacuateFollowersClosure: public VoidClosure { private: PSPromotionManager* _promotion_manager; public: PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} virtual void do_void() { assert(_promotion_manager != NULL, "Sanity"); _promotion_manager->drain_stacks(true); guarantee(_promotion_manager->stacks_empty(), "stacks should be empty at this point"); } }; class PSPromotionFailedClosure : public ObjectClosure { virtual void do_object(oop obj) { if (obj->is_forwarded()) { obj->init_mark(); } } }; class PSRefProcTaskProxy: public GCTask { typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; ProcessTask & _rp_task; uint _work_id; public: PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) : _rp_task(rp_task), _work_id(work_id) { } private: virtual char* name() { return (char *)"Process referents by policy in parallel"; } virtual void do_it(GCTaskManager* manager, uint which); }; void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) { PSPromotionManager* promotion_manager = PSPromotionManager::gc_thread_promotion_manager(which); assert(promotion_manager != NULL, "sanity check"); PSKeepAliveClosure keep_alive(promotion_manager); PSEvacuateFollowersClosure evac_followers(promotion_manager); PSIsAliveClosure is_alive; _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); } class PSRefEnqueueTaskProxy: public GCTask { typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; EnqueueTask& _enq_task; uint _work_id; public: PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) : _enq_task(enq_task), _work_id(work_id) { } virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } virtual void do_it(GCTaskManager* manager, uint which) { _enq_task.work(_work_id); } }; class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { virtual void execute(ProcessTask& task); virtual void execute(EnqueueTask& task); }; void PSRefProcTaskExecutor::execute(ProcessTask& task) { GCTaskQueue* q = GCTaskQueue::create(); GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); for(uint i=0; i < manager->active_workers(); i++) { q->enqueue(new PSRefProcTaskProxy(task, i)); } ParallelTaskTerminator terminator(manager->active_workers(), (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); if (task.marks_oops_alive() && manager->active_workers() > 1) { for (uint j = 0; j < manager->active_workers(); j++) { q->enqueue(new StealTask(&terminator)); } } manager->execute_and_wait(q); } void PSRefProcTaskExecutor::execute(EnqueueTask& task) { GCTaskQueue* q = GCTaskQueue::create(); GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); for(uint i=0; i < manager->active_workers(); i++) { q->enqueue(new PSRefEnqueueTaskProxy(task, i)); } manager->execute_and_wait(q); } // This method contains all heap specific policy for invoking scavenge. // PSScavenge::invoke_no_policy() will do nothing but attempt to // scavenge. It will not clean up after failed promotions, bail out if // we've exceeded policy time limits, or any other special behavior. // All such policy should be placed here. // // Note that this method should only be called from the vm_thread while // at a safepoint! bool PSScavenge::invoke() { assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); assert(!Universe::heap()->is_gc_active(), "not reentrant"); ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); PSAdaptiveSizePolicy* policy = heap->size_policy(); IsGCActiveMark mark; const bool scavenge_done = PSScavenge::invoke_no_policy(); const bool need_full_gc = !scavenge_done || policy->should_full_GC(heap->old_gen()->free_in_bytes()); bool full_gc_done = false; if (UsePerfData) { PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; counters->update_full_follows_scavenge(ffs_val); } if (need_full_gc) { GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); CollectorPolicy* cp = heap->collector_policy(); const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); if (UseParallelOldGC) { full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); } else { full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs); } } return full_gc_done; } // This method contains no policy. You should probably // be calling invoke() instead. bool PSScavenge::invoke_no_policy() { assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); assert(_preserved_mark_stack.is_empty(), "should be empty"); assert(_preserved_oop_stack.is_empty(), "should be empty"); _gc_timer.register_gc_start(); TimeStamp scavenge_entry; TimeStamp scavenge_midpoint; TimeStamp scavenge_exit; scavenge_entry.update(); if (GC_locker::check_active_before_gc()) { return false; } ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); GCCause::Cause gc_cause = heap->gc_cause(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); // Check for potential problems. if (!should_attempt_scavenge()) { return false; } _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); bool promotion_failure_occurred = false; PSYoungGen* young_gen = heap->young_gen(); PSOldGen* old_gen = heap->old_gen(); PSPermGen* perm_gen = heap->perm_gen(); PSAdaptiveSizePolicy* size_policy = heap->size_policy(); heap->increment_total_collections(); AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); if ((gc_cause != GCCause::_java_lang_system_gc) || UseAdaptiveSizePolicyWithSystemGC) { // Gather the feedback data for eden occupancy. young_gen->eden_space()->accumulate_statistics(); } if (ZapUnusedHeapArea) { // Save information needed to minimize mangling heap->record_gen_tops_before_GC(); } heap->print_heap_before_gc(); heap->trace_heap_before_gc(&_gc_tracer); assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); size_t prev_used = heap->used(); // Fill in TLABs heap->accumulate_statistics_all_tlabs(); heap->ensure_parsability(true); // retire TLABs if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification Universe::verify(" VerifyBeforeGC:"); } { ResourceMark rm; HandleMark hm; TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); TraceCollectorStats tcs(counters()); TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); if (TraceGen0Time) accumulated_time()->start(); // Let the size policy know we're starting size_policy->minor_collection_begin(); // Verify the object start arrays. if (VerifyObjectStartArray && VerifyBeforeGC) { old_gen->verify_object_start_array(); perm_gen->verify_object_start_array(); } // Verify no unmarked old->young roots if (VerifyRememberedSets) { CardTableExtension::verify_all_young_refs_imprecise(); } if (!ScavengeWithObjectsInToSpace) { assert(young_gen->to_space()->is_empty(), "Attempt to scavenge with live objects in to_space"); young_gen->to_space()->clear(SpaceDecorator::Mangle); } else if (ZapUnusedHeapArea) { young_gen->to_space()->mangle_unused_area(); } save_to_space_top_before_gc(); COMPILER2_PRESENT(DerivedPointerTable::clear()); reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); reference_processor()->setup_policy(false); // We track how much was promoted to the next generation for // the AdaptiveSizePolicy. size_t old_gen_used_before = old_gen->used_in_bytes(); // For PrintGCDetails size_t young_gen_used_before = young_gen->used_in_bytes(); // Reset our survivor overflow. set_survivor_overflow(false); // We need to save the old/perm top values before // creating the promotion_manager. We pass the top // values to the card_table, to prevent it from // straying into the promotion labs. HeapWord* old_top = old_gen->object_space()->top(); HeapWord* perm_top = perm_gen->object_space()->top(); // Release all previously held resources gc_task_manager()->release_all_resources(); // Set the number of GC threads to be used in this collection gc_task_manager()->set_active_gang(); gc_task_manager()->task_idle_workers(); // Get the active number of workers here and use that value // throughout the methods. uint active_workers = gc_task_manager()->active_workers(); heap->set_par_threads(active_workers); PSPromotionManager::pre_scavenge(); // We'll use the promotion manager again later. PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); { GCTraceTime tm("Scavenge", false, false, &_gc_timer); ParallelScavengeHeap::ParStrongRootsScope psrs; GCTaskQueue* q = GCTaskQueue::create(); uint stripe_total = active_workers; for(uint i=0; i < stripe_total; i++) { q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); } q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top)); q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); // We scan the thread roots in parallel Threads::create_thread_roots_tasks(q); q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); ParallelTaskTerminator terminator( active_workers, (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); if (active_workers > 1) { for (uint j = 0; j < active_workers; j++) { q->enqueue(new StealTask(&terminator)); } } gc_task_manager()->execute_and_wait(q); } scavenge_midpoint.update(); // Process reference objects discovered during scavenge { GCTraceTime tm("References", false, false, &_gc_timer); reference_processor()->setup_policy(false); // not always_clear reference_processor()->set_active_mt_degree(active_workers); PSKeepAliveClosure keep_alive(promotion_manager); PSEvacuateFollowersClosure evac_followers(promotion_manager); ReferenceProcessorStats stats; if (reference_processor()->processing_is_mt()) { PSRefProcTaskExecutor task_executor; stats = reference_processor()->process_discovered_references( &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, &_gc_timer); } else { stats = reference_processor()->process_discovered_references( &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer); } _gc_tracer.report_gc_reference_stats(stats); // Enqueue reference objects discovered during scavenge. if (reference_processor()->processing_is_mt()) { PSRefProcTaskExecutor task_executor; reference_processor()->enqueue_discovered_references(&task_executor); } else { reference_processor()->enqueue_discovered_references(NULL); } } if (!JavaObjectsInPerm) { GCTraceTime tm("StringTable", false, false, &_gc_timer); // Unlink any dead interned Strings StringTable::unlink(&_is_alive_closure); // Process the remaining live ones PSScavengeRootsClosure root_closure(promotion_manager); StringTable::oops_do(&root_closure); } // Finally, flush the promotion_manager's labs, and deallocate its stacks. promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); if (promotion_failure_occurred) { clean_up_failed_promotion(); if (PrintGC) { gclog_or_tty->print("--"); } } // Let the size policy know we're done. Note that we count promotion // failure cleanup time as part of the collection (otherwise, we're // implicitly saying it's mutator time). size_policy->minor_collection_end(gc_cause); if (!promotion_failure_occurred) { // Swap the survivor spaces. young_gen->eden_space()->clear(SpaceDecorator::Mangle); young_gen->from_space()->clear(SpaceDecorator::Mangle); young_gen->swap_spaces(); size_t survived = young_gen->from_space()->used_in_bytes(); size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; size_policy->update_averages(_survivor_overflow, survived, promoted); // A successful scavenge should restart the GC time limit count which is // for full GC's. size_policy->reset_gc_overhead_limit_count(); if (UseAdaptiveSizePolicy) { // Calculate the new survivor size and tenuring threshold if (PrintAdaptiveSizePolicy) { gclog_or_tty->print("AdaptiveSizeStart: "); gclog_or_tty->stamp(); gclog_or_tty->print_cr(" collection: %d ", heap->total_collections()); if (Verbose) { gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" " perm_gen_capacity: %d ", old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), perm_gen->capacity_in_bytes()); } } if (UsePerfData) { PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); counters->update_old_eden_size( size_policy->calculated_eden_size_in_bytes()); counters->update_old_promo_size( size_policy->calculated_promo_size_in_bytes()); counters->update_old_capacity(old_gen->capacity_in_bytes()); counters->update_young_capacity(young_gen->capacity_in_bytes()); counters->update_survived(survived); counters->update_promoted(promoted); counters->update_survivor_overflowed(_survivor_overflow); } size_t max_young_size = young_gen->max_size(); // Deciding a free ratio in the young generation is tricky, so if // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating // that the old generation size may have been limited because of them) we // should then limit our young generation size using NewRatio to have it // follow the old generation size. if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); } size_t survivor_limit = size_policy->max_survivor_size(max_young_size); _tenuring_threshold = size_policy->compute_survivor_space_size_and_threshold( _survivor_overflow, _tenuring_threshold, survivor_limit); if (PrintTenuringDistribution) { gclog_or_tty->cr(); gclog_or_tty->print_cr("Desired survivor size %ld bytes, new threshold %d (max %d)", size_policy->calculated_survivor_size_in_bytes(), _tenuring_threshold, MaxTenuringThreshold); } if (UsePerfData) { PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); counters->update_tenuring_threshold(_tenuring_threshold); counters->update_survivor_size_counters(); } // Do call at minor collections? // Don't check if the size_policy is ready at this // level. Let the size_policy check that internally. if (UseAdaptiveGenerationSizePolicyAtMinorCollection && ((gc_cause != GCCause::_java_lang_system_gc) || UseAdaptiveSizePolicyWithSystemGC)) { // Calculate optimial free space amounts assert(young_gen->max_size() > young_gen->from_space()->capacity_in_bytes() + young_gen->to_space()->capacity_in_bytes(), "Sizes of space in young gen are out-of-bounds"); size_t max_eden_size = max_young_size - young_gen->from_space()->capacity_in_bytes() - young_gen->to_space()->capacity_in_bytes(); size_policy->compute_generation_free_space(young_gen->used_in_bytes(), young_gen->eden_space()->used_in_bytes(), old_gen->used_in_bytes(), perm_gen->used_in_bytes(), young_gen->eden_space()->capacity_in_bytes(), old_gen->max_gen_size(), max_eden_size, false /* full gc*/, gc_cause, heap->collector_policy()); } // Resize the young generation at every collection // even if new sizes have not been calculated. This is // to allow resizes that may have been inhibited by the // relative location of the "to" and "from" spaces. // Resizing the old gen at minor collects can cause increases // that don't feed back to the generation sizing policy until // a major collection. Don't resize the old gen here. heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), size_policy->calculated_survivor_size_in_bytes()); if (PrintAdaptiveSizePolicy) { gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", heap->total_collections()); } } // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can // cause the change of the heap layout. Make sure eden is reshaped if that's the case. // Also update() will case adaptive NUMA chunk resizing. assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); young_gen->eden_space()->update(); heap->gc_policy_counters()->update_counters(); heap->resize_all_tlabs(); assert(young_gen->to_space()->is_empty(), "to space should be empty now"); } COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); { GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer); CodeCache::prune_scavenge_root_nmethods(); } // Re-verify object start arrays if (VerifyObjectStartArray && VerifyAfterGC) { old_gen->verify_object_start_array(); perm_gen->verify_object_start_array(); } // Verify all old -> young cards are now precise if (VerifyRememberedSets) { // Precise verification will give false positives. Until this is fixed, // use imprecise verification. // CardTableExtension::verify_all_young_refs_precise(); CardTableExtension::verify_all_young_refs_imprecise(); } if (TraceGen0Time) accumulated_time()->stop(); if (PrintGC) { if (PrintGCDetails) { // Don't print a GC timestamp here. This is after the GC so // would be confusing. young_gen->print_used_change(young_gen_used_before); } heap->print_heap_change(prev_used); } // Track memory usage and detect low memory MemoryService::track_memory_usage(); heap->update_counters(); gc_task_manager()->release_idle_workers(); } if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification Universe::verify(" VerifyAfterGC:"); } heap->print_heap_after_gc(); heap->trace_heap_after_gc(&_gc_tracer); _gc_tracer.report_tenuring_threshold(tenuring_threshold()); if (ZapUnusedHeapArea) { young_gen->eden_space()->check_mangled_unused_area_complete(); young_gen->from_space()->check_mangled_unused_area_complete(); young_gen->to_space()->check_mangled_unused_area_complete(); } scavenge_exit.update(); if (PrintGCTaskTimeStamps) { tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT, scavenge_entry.ticks(), scavenge_midpoint.ticks(), scavenge_exit.ticks()); gc_task_manager()->print_task_time_stamps(); } #ifdef TRACESPINNING ParallelTaskTerminator::print_termination_counts(); #endif _gc_timer.register_gc_end(); _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); return !promotion_failure_occurred; } // This method iterates over all objects in the young generation, // unforwarding markOops. It then restores any preserved mark oops, // and clears the _preserved_mark_stack. void PSScavenge::clean_up_failed_promotion() { ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); PSYoungGen* young_gen = heap->young_gen(); { ResourceMark rm; // Unforward all pointers in the young gen. PSPromotionFailedClosure unforward_closure; young_gen->object_iterate(&unforward_closure); if (PrintGC && Verbose) { gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size()); } // Restore any saved marks. while (!_preserved_oop_stack.is_empty()) { oop obj = _preserved_oop_stack.pop(); markOop mark = _preserved_mark_stack.pop(); obj->set_mark(mark); } // Clear the preserved mark and oop stack caches. _preserved_mark_stack.clear(true); _preserved_oop_stack.clear(true); } // Reset the PromotionFailureALot counters. NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) } // This method is called whenever an attempt to promote an object // fails. Some markOops will need preservation, some will not. Note // that the entire eden is traversed after a failed promotion, with // all forwarded headers replaced by the default markOop. This means // it is not necessary to preserve most markOops. void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { // Should use per-worker private stacks here rather than // locking a common pair of stacks. ThreadCritical tc; _preserved_oop_stack.push(obj); _preserved_mark_stack.push(obj_mark); } } bool PSScavenge::should_attempt_scavenge() { ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); if (UsePerfData) { counters->update_scavenge_skipped(not_skipped); } PSYoungGen* young_gen = heap->young_gen(); PSOldGen* old_gen = heap->old_gen(); if (!ScavengeWithObjectsInToSpace) { // Do not attempt to promote unless to_space is empty if (!young_gen->to_space()->is_empty()) { _consecutive_skipped_scavenges++; if (UsePerfData) { counters->update_scavenge_skipped(to_space_not_empty); } return false; } } // Test to see if the scavenge will likely fail. PSAdaptiveSizePolicy* policy = heap->size_policy(); // A similar test is done in the policy's should_full_GC(). If this is // changed, decide if that test should also be changed. size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); bool result = promotion_estimate < old_gen->free_in_bytes(); if (PrintGCDetails && Verbose) { gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT, (size_t) policy->average_promoted_in_bytes(), (size_t) policy->padded_average_promoted_in_bytes(), old_gen->free_in_bytes()); if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) { gclog_or_tty->print_cr(" padded_promoted_average is greater" " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); } } if (result) { _consecutive_skipped_scavenges = 0; } else { _consecutive_skipped_scavenges++; if (UsePerfData) { counters->update_scavenge_skipped(promoted_too_large); } } return result; } // Used to add tasks GCTaskManager* const PSScavenge::gc_task_manager() { assert(ParallelScavengeHeap::gc_task_manager() != NULL, "shouldn't return NULL"); return ParallelScavengeHeap::gc_task_manager(); } void PSScavenge::initialize() { // Arguments must have been parsed if (AlwaysTenure) { _tenuring_threshold = 0; } else if (NeverTenure) { _tenuring_threshold = markOopDesc::max_age + 1; } else { // We want to smooth out our startup times for the AdaptiveSizePolicy _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : MaxTenuringThreshold; } ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); PSYoungGen* young_gen = heap->young_gen(); PSOldGen* old_gen = heap->old_gen(); PSPermGen* perm_gen = heap->perm_gen(); // Set boundary between young_gen and old_gen assert(perm_gen->reserved().end() <= old_gen->object_space()->bottom(), "perm above old"); assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), "old above young"); _young_generation_boundary = young_gen->eden_space()->bottom(); // Initialize ref handling object for scavenging. MemRegion mr = young_gen->reserved(); _ref_processor = new ReferenceProcessor(mr, // span ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing (int) ParallelGCThreads, // mt processing degree true, // mt discovery (int) ParallelGCThreads, // mt discovery degree true, // atomic_discovery NULL, // header provides liveness info false); // next field updates do not need write barrier // Cache the cardtable BarrierSet* bs = Universe::heap()->barrier_set(); assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind"); _card_table = (CardTableExtension*)bs; _counters = new CollectorCounters("PSScavenge", 0); }