< prev index next > src/hotspot/share/gc/parallel/psScavenge.cpp
8224663: Parallel GC: Use WorkGang (5: ScavengeRootsTask)
* questions.
*
*/
#include "precompiled.hpp"
+#include "aot/aotLoader.hpp"
+#include "classfile/classLoaderDataGraph.hpp"
#include "classfile/stringTable.hpp"
#include "code/codeCache.hpp"
#include "gc/parallel/gcTaskManager.hpp"
#include "gc/parallel/parallelScavengeHeap.hpp"
#include "gc/parallel/psAdaptiveSizePolicy.hpp"
#include "gc/parallel/psClosure.inline.hpp"
#include "gc/parallel/psMarkSweepProxy.hpp"
#include "gc/parallel/psParallelCompact.inline.hpp"
#include "gc/parallel/psPromotionManager.inline.hpp"
+#include "gc/parallel/psRootType.inline.hpp"
#include "gc/parallel/psScavenge.inline.hpp"
#include "gc/parallel/psTasks.hpp"
#include "gc/shared/gcCause.hpp"
#include "gc/shared/gcHeapSummary.hpp"
#include "gc/shared/gcId.hpp"
#include "gc/shared/gcTraceTime.inline.hpp"
#include "gc/shared/isGCActiveMark.hpp"
#include "gc/shared/referencePolicy.hpp"
#include "gc/shared/referenceProcessor.hpp"
#include "gc/shared/referenceProcessorPhaseTimes.hpp"
+#include "gc/shared/scavengableNMethods.hpp"
#include "gc/shared/spaceDecorator.hpp"
#include "gc/shared/weakProcessor.hpp"
#include "gc/shared/workerPolicy.hpp"
+#include "gc/shared/workgroup.hpp"
+#if INCLUDE_JVMCI
+#include "jvmci/jvmci.hpp"
+#endif
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "logging/log.hpp"
#include "oops/access.inline.hpp"
#include "oops/compressedOops.inline.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/threadCritical.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vmOperations.hpp"
+#include "services/management.hpp"
#include "services/memoryService.hpp"
#include "utilities/stack.inline.hpp"
+
HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
int PSScavenge::_consecutive_skipped_scavenges = 0;
SpanSubjectToDiscoveryClosure PSScavenge::_span_based_discoverer;
ReferenceProcessor* PSScavenge::_ref_processor = NULL;
PSCardTable* PSScavenge::_card_table = NULL;
elapsedTimer PSScavenge::_accumulated_time;
STWGCTimer PSScavenge::_gc_timer;
ParallelScavengeTracer PSScavenge::_gc_tracer;
CollectorCounters* PSScavenge::_counters = NULL;
+void scavenge_roots_task(Parallel::RootType::Value root_type, uint which) {
+ assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
+
+ PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(which);
+ PSScavengeRootsClosure roots_closure(pm);
+ PSPromoteRootsClosure roots_to_old_closure(pm);
+
+ switch (root_type) {
+ case Parallel::RootType::universe:
+ Universe::oops_do(&roots_closure);
+ break;
+
+ case Parallel::RootType::jni_handles:
+ JNIHandles::oops_do(&roots_closure);
+ break;
+
+ case Parallel::RootType::object_synchronizer:
+ ObjectSynchronizer::oops_do(&roots_closure);
+ break;
+
+ case Parallel::RootType::system_dictionary:
+ SystemDictionary::oops_do(&roots_closure);
+ break;
+
+ case Parallel::RootType::class_loader_data:
+ {
+ PSScavengeCLDClosure cld_closure(pm);
+ ClassLoaderDataGraph::cld_do(&cld_closure);
+ }
+ break;
+
+ case Parallel::RootType::management:
+ Management::oops_do(&roots_closure);
+ break;
+
+ case Parallel::RootType::jvmti:
+ JvmtiExport::oops_do(&roots_closure);
+ break;
+
+ case Parallel::RootType::code_cache:
+ {
+ MarkingCodeBlobClosure code_closure(&roots_to_old_closure, CodeBlobToOopClosure::FixRelocations);
+ ScavengableNMethods::nmethods_do(&code_closure);
+ AOTLoader::oops_do(&roots_closure);
+ }
+ break;
+
+#if INCLUDE_JVMCI
+ case Parallel::RootType::jvmci:
+ JVMCI::oops_do(&roots_closure);
+ break;
+#endif
+
+ case Parallel::RootType::sentinel:
+ DEBUG_ONLY(default:) // DEBUG_ONLY hack will create compile error on release builds (-Wswitch) and runtime check on debug builds
+ fatal("Bad enumeration value: %u", root_type);
+ break;
+ }
+
+ // Do the real work
+ pm->drain_stacks(false);
+}
+
+void steal_task(ParallelTaskTerminator& terminator, uint worker_id) {
+ assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
+
+ PSPromotionManager* pm =
+ PSPromotionManager::gc_thread_promotion_manager(worker_id);
+ pm->drain_stacks(true);
+ guarantee(pm->stacks_empty(),
+ "stacks should be empty at this point");
+
+ while (true) {
+ StarTask p;
+ if (PSPromotionManager::steal_depth(worker_id, p)) {
+ TASKQUEUE_STATS_ONLY(pm->record_steal(p));
+ pm->process_popped_location_depth(p);
+ pm->drain_stacks_depth(true);
+ } else {
+ if (terminator.offer_termination()) {
+ break;
+ }
+ }
+ }
+ guarantee(pm->stacks_empty(), "stacks should be empty at this point");
+}
+
// Define before use
class PSIsAliveClosure: public BoolObjectClosure {
public:
bool do_object_b(oop p) {
return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
}
return full_gc_done;
}
-class PSAddThreadRootsTaskClosure : public ThreadClosure {
-private:
- GCTaskQueue* _q;
+class PSThreadRootsTaskClosure : public ThreadClosure {
+ uint _worker_id;
+public:
+ PSThreadRootsTaskClosure(uint worker_id) : _worker_id(worker_id) { }
+ virtual void do_thread(Thread* thread) {
+ assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
+
+ PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(_worker_id);
+ PSScavengeRootsClosure roots_closure(pm);
+ MarkingCodeBlobClosure roots_in_blobs(&roots_closure, CodeBlobToOopClosure::FixRelocations);
+
+ thread->oops_do(&roots_closure, &roots_in_blobs);
+
+ // Do the real work
+ pm->drain_stacks(false);
+ }
+};
+//
+// OldToYoungRootsTask
+//
+// This task is used to scan old to young roots in parallel
+//
+// A GC thread executing this tasks divides the generation (old gen)
+// into slices and takes a stripe in the slice as its part of the
+// work.
+//
+// +===============+ slice 0
+// | stripe 0 |
+// +---------------+
+// | stripe 1 |
+// +---------------+
+// | stripe 2 |
+// +---------------+
+// | stripe 3 |
+// +===============+ slice 1
+// | stripe 0 |
+// +---------------+
+// | stripe 1 |
+// +---------------+
+// | stripe 2 |
+// +---------------+
+// | stripe 3 |
+// +===============+ slice 2
+// ...
+//
+// A task is created for each stripe. In this case there are 4 tasks
+// created. A GC thread first works on its stripe within slice 0
+// and then moves to its stripe in the next slice until all stripes
+// exceed the top of the generation. Note that having fewer GC threads
+// than stripes works because all the tasks are executed so all stripes
+// will be covered. In this example if 4 tasks have been created to cover
+// all the stripes and there are only 3 threads, one of the threads will
+// get the tasks with the 4th stripe. However, there is a dependence in
+// PSCardTable::scavenge_contents_parallel() on the number
+// of tasks created. In scavenge_contents_parallel the distance
+// to the next stripe is calculated based on the number of tasks.
+// If the stripe width is ssize, a task's next stripe is at
+// ssize * number_of_tasks (= slice_stride). In this case after
+// finishing stripe 0 in slice 0, the thread finds the stripe 0 in slice1
+// by adding slice_stride to the start of stripe 0 in slice 0 to get
+// to the start of stride 0 in slice 1.
+
+class ScavengeRootsTask : public AbstractGangTask {
+ StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
+ EnumClaimer<Parallel::RootType::Value> _enum_claimer;
+ PSOldGen* _old_gen;
+ HeapWord* _gen_top;
+ uint _active_workers;
+ bool _is_empty;
+ TaskTerminator _terminator;
public:
- PSAddThreadRootsTaskClosure(GCTaskQueue* q) : _q(q) { }
- void do_thread(Thread* t) {
- _q->enqueue(new ThreadRootsTask(t));
+ ScavengeRootsTask(
+ PSOldGen* old_gen,
+ HeapWord* gen_top,
+ uint active_workers,
+ bool is_empty)
+ : AbstractGangTask("ScavengeRootsTask"),
+ _strong_roots_scope(active_workers),
+ _enum_claimer(Parallel::RootType::sentinel),
+ _old_gen(old_gen),
+ _gen_top(gen_top),
+ _active_workers(active_workers),
+ _is_empty(is_empty),
+ _terminator(active_workers, PSPromotionManager::vm_thread_promotion_manager()->stack_array_depth()) {
+ }
+
+ virtual void work(uint worker_id) {
+ ResourceMark rm;
+
+ if (!_is_empty) {
+ // There are only old-to-young pointers if there are objects
+ // in the old gen.
+
+ // There are not old-to-young pointers if the old gen is empty.
+ assert(!_old_gen->object_space()->is_empty(),
+ "Should not be called is there is no work");
+ assert(_old_gen != NULL, "Sanity");
+ assert(_old_gen->object_space()->contains(_gen_top) || _gen_top == _old_gen->object_space()->top(), "Sanity");
+ assert(worker_id < ParallelGCThreads, "Sanity");
+
+ {
+ PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
+ PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table();
+
+ card_table->scavenge_contents_parallel(_old_gen->start_array(),
+ _old_gen->object_space(),
+ _gen_top,
+ pm,
+ worker_id,
+ _active_workers);
+
+ // Do the real work
+ pm->drain_stacks(false);
+ }
+ }
+
+ for (Parallel::RootType::Value root_type; _enum_claimer.try_claim(root_type); /* empty */) {
+ scavenge_roots_task(root_type, worker_id);
+ }
+
+ PSThreadRootsTaskClosure closure(worker_id);
+ Threads::possibly_parallel_threads_do(true /*parallel */, &closure);
+
+
+ // If active_workers can exceed 1, add a StrealTask.
+ // PSPromotionManager::drain_stacks_depth() does not fully drain its
+ // stacks and expects a StealTask to complete the draining if
+ // ParallelGCThreads is > 1.
+
+ if (_active_workers > 1) {
+ steal_task(*_terminator.terminator() , worker_id);
+ }
}
};
// This method contains no policy. You should probably
// be calling invoke() instead.
// We'll use the promotion manager again later.
PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
{
GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
- 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
- PSAddThreadRootsTaskClosure cl(q);
- Threads::java_threads_and_vm_thread_do(&cl);
- q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
- 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));
- JVMCI_ONLY(q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmci));)
-
- TaskTerminator terminator(active_workers,
- (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
- // If active_workers can exceed 1, add a StrealTask.
- // PSPromotionManager::drain_stacks_depth() does not fully drain its
- // stacks and expects a StealTask to complete the draining if
- // ParallelGCThreads is > 1.
- if (gc_task_manager()->workers() > 1) {
- for (uint j = 0; j < active_workers; j++) {
- q->enqueue(new StealTask(terminator.terminator()));
- }
- }
- gc_task_manager()->execute_and_wait(q);
+ ScavengeRootsTask task(old_gen, old_top, active_workers, old_gen->object_space()->is_empty());
+ ParallelScavengeHeap::heap()->workers().run_task(&task);
}
scavenge_midpoint.update();
// Process reference objects discovered during scavenge
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