duke@435: /*
hseigel@4465:  * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
jcoomes@2661: #include "classfile/symbolTable.hpp"
iveresov@3536: #include "code/codeCache.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/generationSizer.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
stefank@2314: #include "gc_implementation/parallelScavenge/psTasks.hpp"
stefank@2314: #include "gc_implementation/shared/isGCActiveMark.hpp"
stefank@2314: #include "gc_implementation/shared/spaceDecorator.hpp"
stefank@2314: #include "gc_interface/gcCause.hpp"
stefank@2314: #include "memory/collectorPolicy.hpp"
stefank@2314: #include "memory/gcLocker.inline.hpp"
stefank@2314: #include "memory/referencePolicy.hpp"
stefank@2314: #include "memory/referenceProcessor.hpp"
stefank@2314: #include "memory/resourceArea.hpp"
stefank@2314: #include "oops/oop.inline.hpp"
stefank@2314: #include "oops/oop.psgc.inline.hpp"
stefank@2314: #include "runtime/biasedLocking.hpp"
stefank@2314: #include "runtime/fprofiler.hpp"
stefank@2314: #include "runtime/handles.inline.hpp"
stefank@2314: #include "runtime/threadCritical.hpp"
stefank@2314: #include "runtime/vmThread.hpp"
stefank@2314: #include "runtime/vm_operations.hpp"
stefank@2314: #include "services/memoryService.hpp"
stefank@2314: #include "utilities/stack.inline.hpp"
duke@435: 
duke@435: 
duke@435: HeapWord*                  PSScavenge::_to_space_top_before_gc = NULL;
duke@435: int                        PSScavenge::_consecutive_skipped_scavenges = 0;
duke@435: ReferenceProcessor*        PSScavenge::_ref_processor = NULL;
duke@435: CardTableExtension*        PSScavenge::_card_table = NULL;
duke@435: bool                       PSScavenge::_survivor_overflow = false;
jwilhelm@4129: uint                       PSScavenge::_tenuring_threshold = 0;
duke@435: HeapWord*                  PSScavenge::_young_generation_boundary = NULL;
duke@435: elapsedTimer               PSScavenge::_accumulated_time;
zgu@3900: Stack<markOop, mtGC>       PSScavenge::_preserved_mark_stack;
zgu@3900: Stack<oop, mtGC>           PSScavenge::_preserved_oop_stack;
duke@435: CollectorCounters*         PSScavenge::_counters = NULL;
jcoomes@2191: bool                       PSScavenge::_promotion_failed = false;
duke@435: 
duke@435: // Define before use
duke@435: class PSIsAliveClosure: public BoolObjectClosure {
duke@435: public:
duke@435:   bool do_object_b(oop p) {
duke@435:     return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded();
duke@435:   }
duke@435: };
duke@435: 
duke@435: PSIsAliveClosure PSScavenge::_is_alive_closure;
duke@435: 
duke@435: class PSKeepAliveClosure: public OopClosure {
duke@435: protected:
duke@435:   MutableSpace* _to_space;
duke@435:   PSPromotionManager* _promotion_manager;
duke@435: 
duke@435: public:
duke@435:   PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
duke@435:     ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
duke@435:     assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
duke@435:     _to_space = heap->young_gen()->to_space();
duke@435: 
duke@435:     assert(_promotion_manager != NULL, "Sanity");
duke@435:   }
duke@435: 
coleenp@548:   template <class T> void do_oop_work(T* p) {
coleenp@548:     assert (!oopDesc::is_null(*p), "expected non-null ref");
coleenp@548:     assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
coleenp@548:             "expected an oop while scanning weak refs");
duke@435: 
duke@435:     // Weak refs may be visited more than once.
coleenp@548:     if (PSScavenge::should_scavenge(p, _to_space)) {
iveresov@3536:       PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p);
duke@435:     }
duke@435:   }
coleenp@548:   virtual void do_oop(oop* p)       { PSKeepAliveClosure::do_oop_work(p); }
coleenp@548:   virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
duke@435: };
duke@435: 
duke@435: class PSEvacuateFollowersClosure: public VoidClosure {
duke@435:  private:
duke@435:   PSPromotionManager* _promotion_manager;
duke@435:  public:
duke@435:   PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
duke@435: 
coleenp@548:   virtual void do_void() {
duke@435:     assert(_promotion_manager != NULL, "Sanity");
duke@435:     _promotion_manager->drain_stacks(true);
duke@435:     guarantee(_promotion_manager->stacks_empty(),
duke@435:               "stacks should be empty at this point");
duke@435:   }
duke@435: };
duke@435: 
duke@435: class PSPromotionFailedClosure : public ObjectClosure {
duke@435:   virtual void do_object(oop obj) {
duke@435:     if (obj->is_forwarded()) {
duke@435:       obj->init_mark();
duke@435:     }
duke@435:   }
duke@435: };
duke@435: 
duke@435: class PSRefProcTaskProxy: public GCTask {
duke@435:   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
duke@435:   ProcessTask & _rp_task;
duke@435:   uint          _work_id;
duke@435: public:
duke@435:   PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
duke@435:     : _rp_task(rp_task),
duke@435:       _work_id(work_id)
duke@435:   { }
duke@435: 
duke@435: private:
duke@435:   virtual char* name() { return (char *)"Process referents by policy in parallel"; }
duke@435:   virtual void do_it(GCTaskManager* manager, uint which);
duke@435: };
duke@435: 
duke@435: void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
duke@435: {
duke@435:   PSPromotionManager* promotion_manager =
duke@435:     PSPromotionManager::gc_thread_promotion_manager(which);
duke@435:   assert(promotion_manager != NULL, "sanity check");
duke@435:   PSKeepAliveClosure keep_alive(promotion_manager);
duke@435:   PSEvacuateFollowersClosure evac_followers(promotion_manager);
duke@435:   PSIsAliveClosure is_alive;
duke@435:   _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
duke@435: }
duke@435: 
duke@435: class PSRefEnqueueTaskProxy: public GCTask {
duke@435:   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
duke@435:   EnqueueTask& _enq_task;
duke@435:   uint         _work_id;
duke@435: 
duke@435: public:
duke@435:   PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
duke@435:     : _enq_task(enq_task),
duke@435:       _work_id(work_id)
duke@435:   { }
duke@435: 
duke@435:   virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
duke@435:   virtual void do_it(GCTaskManager* manager, uint which)
duke@435:   {
duke@435:     _enq_task.work(_work_id);
duke@435:   }
duke@435: };
duke@435: 
duke@435: class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
duke@435:   virtual void execute(ProcessTask& task);
duke@435:   virtual void execute(EnqueueTask& task);
duke@435: };
duke@435: 
duke@435: void PSRefProcTaskExecutor::execute(ProcessTask& task)
duke@435: {
duke@435:   GCTaskQueue* q = GCTaskQueue::create();
jmasa@3294:   GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
jmasa@3294:   for(uint i=0; i < manager->active_workers(); i++) {
duke@435:     q->enqueue(new PSRefProcTaskProxy(task, i));
duke@435:   }
jmasa@3294:   ParallelTaskTerminator terminator(manager->active_workers(),
tonyp@2061:                  (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
jmasa@3294:   if (task.marks_oops_alive() && manager->active_workers() > 1) {
jmasa@3294:     for (uint j = 0; j < manager->active_workers(); j++) {
duke@435:       q->enqueue(new StealTask(&terminator));
duke@435:     }
duke@435:   }
jmasa@3294:   manager->execute_and_wait(q);
duke@435: }
duke@435: 
duke@435: 
duke@435: void PSRefProcTaskExecutor::execute(EnqueueTask& task)
duke@435: {
duke@435:   GCTaskQueue* q = GCTaskQueue::create();
jmasa@3294:   GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
jmasa@3294:   for(uint i=0; i < manager->active_workers(); i++) {
duke@435:     q->enqueue(new PSRefEnqueueTaskProxy(task, i));
duke@435:   }
jmasa@3294:   manager->execute_and_wait(q);
duke@435: }
duke@435: 
duke@435: // This method contains all heap specific policy for invoking scavenge.
duke@435: // PSScavenge::invoke_no_policy() will do nothing but attempt to
duke@435: // scavenge. It will not clean up after failed promotions, bail out if
duke@435: // we've exceeded policy time limits, or any other special behavior.
duke@435: // All such policy should be placed here.
duke@435: //
duke@435: // Note that this method should only be called from the vm_thread while
duke@435: // at a safepoint!
jcoomes@3540: bool PSScavenge::invoke() {
duke@435:   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
duke@435:   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
duke@435:   assert(!Universe::heap()->is_gc_active(), "not reentrant");
duke@435: 
jcoomes@3540:   ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap();
duke@435:   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
duke@435: 
duke@435:   PSAdaptiveSizePolicy* policy = heap->size_policy();
jmasa@1822:   IsGCActiveMark mark;
duke@435: 
jcoomes@3540:   const bool scavenge_done = PSScavenge::invoke_no_policy();
jcoomes@3540:   const bool need_full_gc = !scavenge_done ||
jcoomes@3540:     policy->should_full_GC(heap->old_gen()->free_in_bytes());
jcoomes@3540:   bool full_gc_done = false;
duke@435: 
jcoomes@3540:   if (UsePerfData) {
jcoomes@3540:     PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
jcoomes@3540:     const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
jcoomes@3540:     counters->update_full_follows_scavenge(ffs_val);
jcoomes@3540:   }
jcoomes@3540: 
jcoomes@3540:   if (need_full_gc) {
jmasa@1822:     GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
jmasa@1822:     CollectorPolicy* cp = heap->collector_policy();
jmasa@1822:     const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
duke@435: 
jmasa@1822:     if (UseParallelOldGC) {
jcoomes@3540:       full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
jmasa@1822:     } else {
jcoomes@3540:       full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
duke@435:     }
duke@435:   }
jcoomes@3540: 
jcoomes@3540:   return full_gc_done;
duke@435: }
duke@435: 
duke@435: // This method contains no policy. You should probably
duke@435: // be calling invoke() instead.
duke@435: bool PSScavenge::invoke_no_policy() {
duke@435:   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
duke@435:   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
duke@435: 
jcoomes@2191:   assert(_preserved_mark_stack.is_empty(), "should be empty");
jcoomes@2191:   assert(_preserved_oop_stack.is_empty(), "should be empty");
jcoomes@2191: 
duke@435:   TimeStamp scavenge_entry;
duke@435:   TimeStamp scavenge_midpoint;
duke@435:   TimeStamp scavenge_exit;
duke@435: 
duke@435:   scavenge_entry.update();
duke@435: 
duke@435:   if (GC_locker::check_active_before_gc()) {
duke@435:     return false;
duke@435:   }
duke@435: 
duke@435:   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
duke@435:   GCCause::Cause gc_cause = heap->gc_cause();
duke@435:   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
duke@435: 
duke@435:   // Check for potential problems.
duke@435:   if (!should_attempt_scavenge()) {
duke@435:     return false;
duke@435:   }
duke@435: 
duke@435:   bool promotion_failure_occurred = false;
duke@435: 
duke@435:   PSYoungGen* young_gen = heap->young_gen();
duke@435:   PSOldGen* old_gen = heap->old_gen();
duke@435:   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
duke@435:   heap->increment_total_collections();
duke@435: 
duke@435:   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
duke@435: 
duke@435:   if ((gc_cause != GCCause::_java_lang_system_gc) ||
duke@435:        UseAdaptiveSizePolicyWithSystemGC) {
duke@435:     // Gather the feedback data for eden occupancy.
duke@435:     young_gen->eden_space()->accumulate_statistics();
duke@435:   }
duke@435: 
jmasa@698:   if (ZapUnusedHeapArea) {
jmasa@698:     // Save information needed to minimize mangling
jmasa@698:     heap->record_gen_tops_before_GC();
jmasa@698:   }
jmasa@698: 
never@3499:   heap->print_heap_before_gc();
duke@435: 
duke@435:   assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
duke@435:   assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
duke@435: 
duke@435:   size_t prev_used = heap->used();
duke@435:   assert(promotion_failed() == false, "Sanity");
duke@435: 
duke@435:   // Fill in TLABs
duke@435:   heap->accumulate_statistics_all_tlabs();
duke@435:   heap->ensure_parsability(true);  // retire TLABs
duke@435: 
duke@435:   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
duke@435:     HandleMark hm;  // Discard invalid handles created during verification
stefank@5018:     Universe::verify(" VerifyBeforeGC:");
duke@435:   }
duke@435: 
duke@435:   {
duke@435:     ResourceMark rm;
duke@435:     HandleMark hm;
duke@435: 
duke@435:     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
duke@435:     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
brutisso@3767:     TraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty);
duke@435:     TraceCollectorStats tcs(counters());
fparain@2888:     TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
duke@435: 
duke@435:     if (TraceGen0Time) accumulated_time()->start();
duke@435: 
duke@435:     // Let the size policy know we're starting
duke@435:     size_policy->minor_collection_begin();
duke@435: 
duke@435:     // Verify the object start arrays.
duke@435:     if (VerifyObjectStartArray &&
duke@435:         VerifyBeforeGC) {
duke@435:       old_gen->verify_object_start_array();
duke@435:     }
duke@435: 
duke@435:     // Verify no unmarked old->young roots
duke@435:     if (VerifyRememberedSets) {
duke@435:       CardTableExtension::verify_all_young_refs_imprecise();
duke@435:     }
duke@435: 
duke@435:     if (!ScavengeWithObjectsInToSpace) {
duke@435:       assert(young_gen->to_space()->is_empty(),
duke@435:              "Attempt to scavenge with live objects in to_space");
jmasa@698:       young_gen->to_space()->clear(SpaceDecorator::Mangle);
duke@435:     } else if (ZapUnusedHeapArea) {
duke@435:       young_gen->to_space()->mangle_unused_area();
duke@435:     }
duke@435:     save_to_space_top_before_gc();
duke@435: 
duke@435:     COMPILER2_PRESENT(DerivedPointerTable::clear());
duke@435: 
johnc@3175:     reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
ysr@892:     reference_processor()->setup_policy(false);
duke@435: 
duke@435:     // We track how much was promoted to the next generation for
duke@435:     // the AdaptiveSizePolicy.
duke@435:     size_t old_gen_used_before = old_gen->used_in_bytes();
duke@435: 
duke@435:     // For PrintGCDetails
duke@435:     size_t young_gen_used_before = young_gen->used_in_bytes();
duke@435: 
duke@435:     // Reset our survivor overflow.
duke@435:     set_survivor_overflow(false);
duke@435: 
coleenp@4037:     // We need to save the old top values before
duke@435:     // creating the promotion_manager. We pass the top
duke@435:     // values to the card_table, to prevent it from
duke@435:     // straying into the promotion labs.
duke@435:     HeapWord* old_top = old_gen->object_space()->top();
duke@435: 
duke@435:     // Release all previously held resources
duke@435:     gc_task_manager()->release_all_resources();
duke@435: 
jmasa@3294:     // Set the number of GC threads to be used in this collection
jmasa@3294:     gc_task_manager()->set_active_gang();
jmasa@3294:     gc_task_manager()->task_idle_workers();
jmasa@3294:     // Get the active number of workers here and use that value
jmasa@3294:     // throughout the methods.
jmasa@3294:     uint active_workers = gc_task_manager()->active_workers();
jmasa@3294:     heap->set_par_threads(active_workers);
jmasa@3294: 
duke@435:     PSPromotionManager::pre_scavenge();
duke@435: 
duke@435:     // We'll use the promotion manager again later.
duke@435:     PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
duke@435:     {
duke@435:       // TraceTime("Roots");
jrose@1424:       ParallelScavengeHeap::ParStrongRootsScope psrs;
duke@435: 
duke@435:       GCTaskQueue* q = GCTaskQueue::create();
duke@435: 
jmasa@4128:       if (!old_gen->object_space()->is_empty()) {
jmasa@4128:         // There are only old-to-young pointers if there are objects
jmasa@4128:         // in the old gen.
jmasa@4128:         uint stripe_total = active_workers;
jmasa@4128:         for(uint i=0; i < stripe_total; i++) {
jmasa@4128:           q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
jmasa@4128:         }
duke@435:       }
duke@435: 
duke@435:       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
duke@435:       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
duke@435:       // We scan the thread roots in parallel
duke@435:       Threads::create_thread_roots_tasks(q);
duke@435:       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
duke@435:       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
duke@435:       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
duke@435:       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
duke@435:       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
jrose@1424:       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
duke@435: 
duke@435:       ParallelTaskTerminator terminator(
jmasa@3294:         active_workers,
tonyp@2061:                   (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
jmasa@3294:       if (active_workers > 1) {
jmasa@3294:         for (uint j = 0; j < active_workers; j++) {
duke@435:           q->enqueue(new StealTask(&terminator));
duke@435:         }
duke@435:       }
duke@435: 
duke@435:       gc_task_manager()->execute_and_wait(q);
duke@435:     }
duke@435: 
duke@435:     scavenge_midpoint.update();
duke@435: 
duke@435:     // Process reference objects discovered during scavenge
duke@435:     {
ysr@892:       reference_processor()->setup_policy(false); // not always_clear
jmasa@3294:       reference_processor()->set_active_mt_degree(active_workers);
duke@435:       PSKeepAliveClosure keep_alive(promotion_manager);
duke@435:       PSEvacuateFollowersClosure evac_followers(promotion_manager);
duke@435:       if (reference_processor()->processing_is_mt()) {
duke@435:         PSRefProcTaskExecutor task_executor;
duke@435:         reference_processor()->process_discovered_references(
ysr@888:           &_is_alive_closure, &keep_alive, &evac_followers, &task_executor);
duke@435:       } else {
duke@435:         reference_processor()->process_discovered_references(
ysr@888:           &_is_alive_closure, &keep_alive, &evac_followers, NULL);
duke@435:       }
duke@435:     }
duke@435: 
duke@435:     // Enqueue reference objects discovered during scavenge.
duke@435:     if (reference_processor()->processing_is_mt()) {
duke@435:       PSRefProcTaskExecutor task_executor;
duke@435:       reference_processor()->enqueue_discovered_references(&task_executor);
duke@435:     } else {
duke@435:       reference_processor()->enqueue_discovered_references(NULL);
duke@435:     }
duke@435: 
jcoomes@2661:       // Unlink any dead interned Strings
jcoomes@2661:       StringTable::unlink(&_is_alive_closure);
jcoomes@2661:       // Process the remaining live ones
jcoomes@2661:       PSScavengeRootsClosure root_closure(promotion_manager);
jcoomes@2661:       StringTable::oops_do(&root_closure);
jcoomes@2661: 
duke@435:     // Finally, flush the promotion_manager's labs, and deallocate its stacks.
duke@435:     PSPromotionManager::post_scavenge();
duke@435: 
duke@435:     promotion_failure_occurred = promotion_failed();
duke@435:     if (promotion_failure_occurred) {
duke@435:       clean_up_failed_promotion();
duke@435:       if (PrintGC) {
duke@435:         gclog_or_tty->print("--");
duke@435:       }
duke@435:     }
duke@435: 
duke@435:     // Let the size policy know we're done.  Note that we count promotion
duke@435:     // failure cleanup time as part of the collection (otherwise, we're
duke@435:     // implicitly saying it's mutator time).
duke@435:     size_policy->minor_collection_end(gc_cause);
duke@435: 
duke@435:     if (!promotion_failure_occurred) {
duke@435:       // Swap the survivor spaces.
jmasa@698: 
jmasa@698: 
jmasa@698:       young_gen->eden_space()->clear(SpaceDecorator::Mangle);
jmasa@698:       young_gen->from_space()->clear(SpaceDecorator::Mangle);
duke@435:       young_gen->swap_spaces();
duke@435: 
duke@435:       size_t survived = young_gen->from_space()->used_in_bytes();
duke@435:       size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
duke@435:       size_policy->update_averages(_survivor_overflow, survived, promoted);
duke@435: 
jmasa@1822:       // A successful scavenge should restart the GC time limit count which is
jmasa@1822:       // for full GC's.
jmasa@1822:       size_policy->reset_gc_overhead_limit_count();
duke@435:       if (UseAdaptiveSizePolicy) {
duke@435:         // Calculate the new survivor size and tenuring threshold
duke@435: 
duke@435:         if (PrintAdaptiveSizePolicy) {
duke@435:           gclog_or_tty->print("AdaptiveSizeStart: ");
duke@435:           gclog_or_tty->stamp();
duke@435:           gclog_or_tty->print_cr(" collection: %d ",
duke@435:                          heap->total_collections());
duke@435: 
duke@435:           if (Verbose) {
coleenp@4037:             gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
coleenp@4037:               old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
duke@435:           }
duke@435:         }
duke@435: 
duke@435: 
duke@435:         if (UsePerfData) {
duke@435:           PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
duke@435:           counters->update_old_eden_size(
duke@435:             size_policy->calculated_eden_size_in_bytes());
duke@435:           counters->update_old_promo_size(
duke@435:             size_policy->calculated_promo_size_in_bytes());
duke@435:           counters->update_old_capacity(old_gen->capacity_in_bytes());
duke@435:           counters->update_young_capacity(young_gen->capacity_in_bytes());
duke@435:           counters->update_survived(survived);
duke@435:           counters->update_promoted(promoted);
duke@435:           counters->update_survivor_overflowed(_survivor_overflow);
duke@435:         }
duke@435: 
duke@435:         size_t survivor_limit =
duke@435:           size_policy->max_survivor_size(young_gen->max_size());
duke@435:         _tenuring_threshold =
duke@435:           size_policy->compute_survivor_space_size_and_threshold(
duke@435:                                                            _survivor_overflow,
duke@435:                                                            _tenuring_threshold,
duke@435:                                                            survivor_limit);
duke@435: 
duke@435:        if (PrintTenuringDistribution) {
duke@435:          gclog_or_tty->cr();
hseigel@4465:          gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max %u)",
duke@435:                                 size_policy->calculated_survivor_size_in_bytes(),
duke@435:                                 _tenuring_threshold, MaxTenuringThreshold);
duke@435:        }
duke@435: 
duke@435:         if (UsePerfData) {
duke@435:           PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
duke@435:           counters->update_tenuring_threshold(_tenuring_threshold);
duke@435:           counters->update_survivor_size_counters();
duke@435:         }
duke@435: 
duke@435:         // Do call at minor collections?
duke@435:         // Don't check if the size_policy is ready at this
duke@435:         // level.  Let the size_policy check that internally.
duke@435:         if (UseAdaptiveSizePolicy &&
duke@435:             UseAdaptiveGenerationSizePolicyAtMinorCollection &&
duke@435:             ((gc_cause != GCCause::_java_lang_system_gc) ||
duke@435:               UseAdaptiveSizePolicyWithSystemGC)) {
duke@435: 
duke@435:           // Calculate optimial free space amounts
duke@435:           assert(young_gen->max_size() >
duke@435:             young_gen->from_space()->capacity_in_bytes() +
duke@435:             young_gen->to_space()->capacity_in_bytes(),
duke@435:             "Sizes of space in young gen are out-of-bounds");
tamao@5120: 
tamao@5120:           size_t young_live = young_gen->used_in_bytes();
tamao@5120:           size_t eden_live = young_gen->eden_space()->used_in_bytes();
tamao@5120:           size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
tamao@5120:           size_t max_old_gen_size = old_gen->max_gen_size();
duke@435:           size_t max_eden_size = young_gen->max_size() -
duke@435:             young_gen->from_space()->capacity_in_bytes() -
duke@435:             young_gen->to_space()->capacity_in_bytes();
duke@435: 
tamao@5120:           // Used for diagnostics
tamao@5120:           size_policy->clear_generation_free_space_flags();
tamao@5120: 
tamao@5120:           size_policy->compute_eden_space_size(young_live,
tamao@5120:                                                eden_live,
tamao@5120:                                                cur_eden,
tamao@5120:                                                max_eden_size,
tamao@5120:                                                false /* not full gc*/);
tamao@5120: 
tamao@5120:           size_policy->check_gc_overhead_limit(young_live,
tamao@5120:                                                eden_live,
tamao@5120:                                                max_old_gen_size,
tamao@5120:                                                max_eden_size,
tamao@5120:                                                false /* not full gc*/,
tamao@5120:                                                gc_cause,
tamao@5120:                                                heap->collector_policy());
tamao@5120: 
tamao@5120:           size_policy->decay_supplemental_growth(false /* not full gc*/);
duke@435:         }
duke@435:         // Resize the young generation at every collection
duke@435:         // even if new sizes have not been calculated.  This is
duke@435:         // to allow resizes that may have been inhibited by the
duke@435:         // relative location of the "to" and "from" spaces.
duke@435: 
duke@435:         // Resizing the old gen at minor collects can cause increases
duke@435:         // that don't feed back to the generation sizing policy until
duke@435:         // a major collection.  Don't resize the old gen here.
duke@435: 
duke@435:         heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
duke@435:                         size_policy->calculated_survivor_size_in_bytes());
duke@435: 
duke@435:         if (PrintAdaptiveSizePolicy) {
duke@435:           gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
duke@435:                          heap->total_collections());
duke@435:         }
duke@435:       }
duke@435: 
duke@435:       // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
duke@435:       // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
duke@435:       // Also update() will case adaptive NUMA chunk resizing.
duke@435:       assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
duke@435:       young_gen->eden_space()->update();
duke@435: 
duke@435:       heap->gc_policy_counters()->update_counters();
duke@435: 
duke@435:       heap->resize_all_tlabs();
duke@435: 
duke@435:       assert(young_gen->to_space()->is_empty(), "to space should be empty now");
duke@435:     }
duke@435: 
duke@435:     COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
duke@435: 
duke@435:     NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
duke@435: 
iveresov@3536:     CodeCache::prune_scavenge_root_nmethods();
iveresov@3536: 
duke@435:     // Re-verify object start arrays
duke@435:     if (VerifyObjectStartArray &&
duke@435:         VerifyAfterGC) {
duke@435:       old_gen->verify_object_start_array();
duke@435:     }
duke@435: 
duke@435:     // Verify all old -> young cards are now precise
duke@435:     if (VerifyRememberedSets) {
duke@435:       // Precise verification will give false positives. Until this is fixed,
duke@435:       // use imprecise verification.
duke@435:       // CardTableExtension::verify_all_young_refs_precise();
duke@435:       CardTableExtension::verify_all_young_refs_imprecise();
duke@435:     }
duke@435: 
duke@435:     if (TraceGen0Time) accumulated_time()->stop();
duke@435: 
duke@435:     if (PrintGC) {
duke@435:       if (PrintGCDetails) {
duke@435:         // Don't print a GC timestamp here.  This is after the GC so
duke@435:         // would be confusing.
duke@435:         young_gen->print_used_change(young_gen_used_before);
duke@435:       }
duke@435:       heap->print_heap_change(prev_used);
duke@435:     }
duke@435: 
duke@435:     // Track memory usage and detect low memory
duke@435:     MemoryService::track_memory_usage();
duke@435:     heap->update_counters();
jmasa@3294: 
jmasa@3294:     gc_task_manager()->release_idle_workers();
duke@435:   }
duke@435: 
duke@435:   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
duke@435:     HandleMark hm;  // Discard invalid handles created during verification
stefank@5018:     Universe::verify(" VerifyAfterGC:");
duke@435:   }
duke@435: 
never@3499:   heap->print_heap_after_gc();
duke@435: 
jmasa@698:   if (ZapUnusedHeapArea) {
jmasa@698:     young_gen->eden_space()->check_mangled_unused_area_complete();
jmasa@698:     young_gen->from_space()->check_mangled_unused_area_complete();
jmasa@698:     young_gen->to_space()->check_mangled_unused_area_complete();
jmasa@698:   }
jmasa@698: 
duke@435:   scavenge_exit.update();
duke@435: 
duke@435:   if (PrintGCTaskTimeStamps) {
duke@435:     tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT,
duke@435:                   scavenge_entry.ticks(), scavenge_midpoint.ticks(),
duke@435:                   scavenge_exit.ticks());
duke@435:     gc_task_manager()->print_task_time_stamps();
duke@435:   }
duke@435: 
jmasa@981: #ifdef TRACESPINNING
jmasa@981:   ParallelTaskTerminator::print_termination_counts();
jmasa@981: #endif
jmasa@981: 
duke@435:   return !promotion_failure_occurred;
duke@435: }
duke@435: 
duke@435: // This method iterates over all objects in the young generation,
duke@435: // unforwarding markOops. It then restores any preserved mark oops,
duke@435: // and clears the _preserved_mark_stack.
duke@435: void PSScavenge::clean_up_failed_promotion() {
duke@435:   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
duke@435:   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
duke@435:   assert(promotion_failed(), "Sanity");
duke@435: 
duke@435:   PSYoungGen* young_gen = heap->young_gen();
duke@435: 
duke@435:   {
duke@435:     ResourceMark rm;
duke@435: 
duke@435:     // Unforward all pointers in the young gen.
duke@435:     PSPromotionFailedClosure unforward_closure;
duke@435:     young_gen->object_iterate(&unforward_closure);
duke@435: 
duke@435:     if (PrintGC && Verbose) {
jcoomes@2191:       gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size());
duke@435:     }
duke@435: 
duke@435:     // Restore any saved marks.
jcoomes@2191:     while (!_preserved_oop_stack.is_empty()) {
jcoomes@2191:       oop obj      = _preserved_oop_stack.pop();
jcoomes@2191:       markOop mark = _preserved_mark_stack.pop();
duke@435:       obj->set_mark(mark);
duke@435:     }
duke@435: 
jcoomes@2191:     // Clear the preserved mark and oop stack caches.
jcoomes@2191:     _preserved_mark_stack.clear(true);
jcoomes@2191:     _preserved_oop_stack.clear(true);
jcoomes@2191:     _promotion_failed = false;
duke@435:   }
duke@435: 
duke@435:   // Reset the PromotionFailureALot counters.
duke@435:   NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
duke@435: }
duke@435: 
duke@435: // This method is called whenever an attempt to promote an object
jcoomes@2191: // fails. Some markOops will need preservation, some will not. Note
duke@435: // that the entire eden is traversed after a failed promotion, with
duke@435: // all forwarded headers replaced by the default markOop. This means
duke@435: // it is not neccessary to preserve most markOops.
duke@435: void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
jcoomes@2191:   _promotion_failed = true;
duke@435:   if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
ysr@2380:     // Should use per-worker private stakcs hetre rather than
ysr@2380:     // locking a common pair of stacks.
duke@435:     ThreadCritical tc;
jcoomes@2191:     _preserved_oop_stack.push(obj);
jcoomes@2191:     _preserved_mark_stack.push(obj_mark);
duke@435:   }
duke@435: }
duke@435: 
duke@435: bool PSScavenge::should_attempt_scavenge() {
duke@435:   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
duke@435:   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
duke@435:   PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
duke@435: 
duke@435:   if (UsePerfData) {
duke@435:     counters->update_scavenge_skipped(not_skipped);
duke@435:   }
duke@435: 
duke@435:   PSYoungGen* young_gen = heap->young_gen();
duke@435:   PSOldGen* old_gen = heap->old_gen();
duke@435: 
duke@435:   if (!ScavengeWithObjectsInToSpace) {
duke@435:     // Do not attempt to promote unless to_space is empty
duke@435:     if (!young_gen->to_space()->is_empty()) {
duke@435:       _consecutive_skipped_scavenges++;
duke@435:       if (UsePerfData) {
duke@435:         counters->update_scavenge_skipped(to_space_not_empty);
duke@435:       }
duke@435:       return false;
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   // Test to see if the scavenge will likely fail.
duke@435:   PSAdaptiveSizePolicy* policy = heap->size_policy();
duke@435: 
duke@435:   // A similar test is done in the policy's should_full_GC().  If this is
duke@435:   // changed, decide if that test should also be changed.
duke@435:   size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
duke@435:   size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
duke@435:   bool result = promotion_estimate < old_gen->free_in_bytes();
duke@435: 
duke@435:   if (PrintGCDetails && Verbose) {
duke@435:     gclog_or_tty->print(result ? "  do scavenge: " : "  skip scavenge: ");
duke@435:     gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
duke@435:       " padded_average_promoted " SIZE_FORMAT
duke@435:       " free in old gen " SIZE_FORMAT,
duke@435:       (size_t) policy->average_promoted_in_bytes(),
duke@435:       (size_t) policy->padded_average_promoted_in_bytes(),
duke@435:       old_gen->free_in_bytes());
duke@435:     if (young_gen->used_in_bytes() <
duke@435:         (size_t) policy->padded_average_promoted_in_bytes()) {
duke@435:       gclog_or_tty->print_cr(" padded_promoted_average is greater"
duke@435:         " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   if (result) {
duke@435:     _consecutive_skipped_scavenges = 0;
duke@435:   } else {
duke@435:     _consecutive_skipped_scavenges++;
duke@435:     if (UsePerfData) {
duke@435:       counters->update_scavenge_skipped(promoted_too_large);
duke@435:     }
duke@435:   }
duke@435:   return result;
duke@435: }
duke@435: 
duke@435:   // Used to add tasks
duke@435: GCTaskManager* const PSScavenge::gc_task_manager() {
duke@435:   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
duke@435:    "shouldn't return NULL");
duke@435:   return ParallelScavengeHeap::gc_task_manager();
duke@435: }
duke@435: 
duke@435: void PSScavenge::initialize() {
duke@435:   // Arguments must have been parsed
duke@435: 
duke@435:   if (AlwaysTenure) {
duke@435:     _tenuring_threshold = 0;
duke@435:   } else if (NeverTenure) {
duke@435:     _tenuring_threshold = markOopDesc::max_age + 1;
duke@435:   } else {
duke@435:     // We want to smooth out our startup times for the AdaptiveSizePolicy
duke@435:     _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
duke@435:                                                     MaxTenuringThreshold;
duke@435:   }
duke@435: 
duke@435:   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
duke@435:   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
duke@435: 
duke@435:   PSYoungGen* young_gen = heap->young_gen();
duke@435:   PSOldGen* old_gen = heap->old_gen();
duke@435: 
duke@435:   // Set boundary between young_gen and old_gen
duke@435:   assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
duke@435:          "old above young");
duke@435:   _young_generation_boundary = young_gen->eden_space()->bottom();
duke@435: 
duke@435:   // Initialize ref handling object for scavenging.
duke@435:   MemRegion mr = young_gen->reserved();
jmasa@3294: 
ysr@2651:   _ref_processor =
ysr@2651:     new ReferenceProcessor(mr,                         // span
ysr@2651:                            ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
ysr@2651:                            (int) ParallelGCThreads,    // mt processing degree
ysr@2651:                            true,                       // mt discovery
ysr@2651:                            (int) ParallelGCThreads,    // mt discovery degree
ysr@2651:                            true,                       // atomic_discovery
ysr@2651:                            NULL,                       // header provides liveness info
ysr@2651:                            false);                     // next field updates do not need write barrier
duke@435: 
duke@435:   // Cache the cardtable
duke@435:   BarrierSet* bs = Universe::heap()->barrier_set();
duke@435:   assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
duke@435:   _card_table = (CardTableExtension*)bs;
duke@435: 
duke@435:   _counters = new CollectorCounters("PSScavenge", 0);
duke@435: }