--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/parallel/psScavenge.cpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,859 @@
+/*
+ * Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/stringTable.hpp"
+#include "code/codeCache.hpp"
+#include "gc/parallel/cardTableExtension.hpp"
+#include "gc/parallel/gcTaskManager.hpp"
+#include "gc/parallel/parallelScavengeHeap.hpp"
+#include "gc/parallel/psAdaptiveSizePolicy.hpp"
+#include "gc/parallel/psMarkSweep.hpp"
+#include "gc/parallel/psParallelCompact.hpp"
+#include "gc/parallel/psScavenge.inline.hpp"
+#include "gc/parallel/psTasks.hpp"
+#include "gc/shared/collectorPolicy.hpp"
+#include "gc/shared/gcCause.hpp"
+#include "gc/shared/gcHeapSummary.hpp"
+#include "gc/shared/gcLocker.inline.hpp"
+#include "gc/shared/gcTimer.hpp"
+#include "gc/shared/gcTrace.hpp"
+#include "gc/shared/gcTraceTime.hpp"
+#include "gc/shared/isGCActiveMark.hpp"
+#include "gc/shared/referencePolicy.hpp"
+#include "gc/shared/referenceProcessor.hpp"
+#include "gc/shared/spaceDecorator.hpp"
+#include "memory/resourceArea.hpp"
+#include "oops/oop.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;
+uint PSScavenge::_tenuring_threshold = 0;
+HeapWord* PSScavenge::_young_generation_boundary = NULL;
+uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
+elapsedTimer PSScavenge::_accumulated_time;
+STWGCTimer PSScavenge::_gc_timer;
+ParallelScavengeTracer PSScavenge::_gc_tracer;
+Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack;
+Stack<oop, mtGC> PSScavenge::_preserved_oop_stack;
+CollectorCounters* PSScavenge::_counters = NULL;
+
+// Define before use
+class PSIsAliveClosure: public BoolObjectClosure {
+public:
+ bool do_object_b(oop p) {
+ return (!PSScavenge::is_obj_in_young(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::heap();
+ _to_space = heap->young_gen()->to_space();
+
+ assert(_promotion_manager != NULL, "Sanity");
+ }
+
+ template <class T> 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)) {
+ _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(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(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
+
+ ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap();
+ 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::heap();
+ GCCause::Cause gc_cause = heap->gc_cause();
+
+ // 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();
+ 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, _gc_tracer.gc_id());
+ TraceCollectorStats tcs(counters());
+ TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
+
+ if (TraceYoungGenTime) 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();
+ }
+
+ // 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();
+ 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 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();
+
+ // 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, _gc_tracer.gc_id());
+ ParallelScavengeHeap::ParStrongRootsScope psrs;
+
+ GCTaskQueue* q = GCTaskQueue::create();
+
+ if (!old_gen->object_space()->is_empty()) {
+ // There are only old-to-young pointers if there are objects
+ // in the old gen.
+ 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 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::class_loader_data));
+ 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, _gc_tracer.gc_id());
+
+ 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, _gc_tracer.gc_id());
+ } else {
+ stats = reference_processor()->process_discovered_references(
+ &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer, _gc_tracer.gc_id());
+ }
+
+ _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);
+ }
+ }
+
+ {
+ GCTraceTime tm("StringTable", false, false, &_gc_timer, _gc_tracer.gc_id());
+ // Unlink any dead interned Strings and process the remaining live ones.
+ PSScavengeRootsClosure root_closure(promotion_manager);
+ StringTable::unlink_or_oops_do(&_is_alive_closure, &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: " SIZE_FORMAT
+ " young_gen_capacity: " SIZE_FORMAT,
+ old_gen->capacity_in_bytes(), young_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 " SIZE_FORMAT " bytes, new threshold %u"
+ " (max threshold " UINTX_FORMAT ")",
+ 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 optimal 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 young_live = young_gen->used_in_bytes();
+ size_t eden_live = young_gen->eden_space()->used_in_bytes();
+ size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
+ size_t max_old_gen_size = old_gen->max_gen_size();
+ size_t max_eden_size = max_young_size -
+ young_gen->from_space()->capacity_in_bytes() -
+ young_gen->to_space()->capacity_in_bytes();
+
+ // Used for diagnostics
+ size_policy->clear_generation_free_space_flags();
+
+ size_policy->compute_eden_space_size(young_live,
+ eden_live,
+ cur_eden,
+ max_eden_size,
+ false /* not full gc*/);
+
+ size_policy->check_gc_overhead_limit(young_live,
+ eden_live,
+ max_old_gen_size,
+ max_eden_size,
+ false /* not full gc*/,
+ gc_cause,
+ heap->collector_policy());
+
+ size_policy->decay_supplemental_growth(false /* not full gc*/);
+ }
+ // 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, _gc_tracer.gc_id());
+
+ CodeCache::prune_scavenge_root_nmethods();
+ }
+
+ // Re-verify object start arrays
+ if (VerifyObjectStartArray &&
+ VerifyAfterGC) {
+ old_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 (TraceYoungGenTime) 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 " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_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::heap();
+ 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 " SIZE_FORMAT " 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(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::heap();
+ 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 || NeverTenure) {
+ assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1,
+ err_msg("MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold));
+ _tenuring_threshold = MaxTenuringThreshold;
+ } else {
+ // We want to smooth out our startup times for the AdaptiveSizePolicy
+ _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
+ MaxTenuringThreshold;
+ }
+
+ ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
+ PSYoungGen* young_gen = heap->young_gen();
+ PSOldGen* old_gen = heap->old_gen();
+
+ // Set boundary between young_gen and old_gen
+ assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
+ "old above young");
+ set_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
+
+ // Cache the cardtable
+ _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set());
+
+ _counters = new CollectorCounters("PSScavenge", 0);
+}