| /* |
| * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved. |
| * |
| * 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 "classfile/systemDictionary.hpp" |
| #include "code/codeCache.hpp" |
| |
| #include "gc/shared/weakProcessor.hpp" |
| #include "gc/shared/gcTimer.hpp" |
| #include "gc/shared/gcTrace.hpp" |
| #include "gc/shared/referenceProcessor.hpp" |
| #include "gc/shared/referenceProcessorPhaseTimes.hpp" |
| |
| #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp" |
| #include "gc/shenandoah/shenandoahClosures.inline.hpp" |
| #include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp" |
| #include "gc/shenandoah/shenandoahMarkCompact.hpp" |
| #include "gc/shenandoah/shenandoahHeap.inline.hpp" |
| #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" |
| #include "gc/shenandoah/shenandoahOopClosures.inline.hpp" |
| #include "gc/shenandoah/shenandoahPhaseTimings.hpp" |
| #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp" |
| #include "gc/shenandoah/shenandoahUtils.hpp" |
| #include "gc/shared/weakProcessor.hpp" |
| |
| #include "memory/iterator.inline.hpp" |
| #include "memory/metaspace.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "oops/oop.inline.hpp" |
| |
| template<UpdateRefsMode UPDATE_REFS> |
| class ShenandoahInitMarkRootsClosure : public OopClosure { |
| private: |
| ShenandoahObjToScanQueue* _queue; |
| ShenandoahHeap* _heap; |
| ShenandoahMarkingContext* const _mark_context; |
| |
| template <class T> |
| inline void do_oop_work(T* p) { |
| ShenandoahConcurrentMark::mark_through_ref<T, UPDATE_REFS, NO_DEDUP>(p, _heap, _queue, _mark_context); |
| } |
| |
| public: |
| ShenandoahInitMarkRootsClosure(ShenandoahObjToScanQueue* q) : |
| _queue(q), |
| _heap(ShenandoahHeap::heap()), |
| _mark_context(_heap->marking_context()) {}; |
| |
| void do_oop(narrowOop* p) { do_oop_work(p); } |
| void do_oop(oop* p) { do_oop_work(p); } |
| }; |
| |
| ShenandoahMarkRefsSuperClosure::ShenandoahMarkRefsSuperClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp) : |
| MetadataVisitingOopIterateClosure(rp), |
| _queue(q), |
| _heap(ShenandoahHeap::heap()), |
| _mark_context(_heap->marking_context()) |
| { } |
| |
| template<UpdateRefsMode UPDATE_REFS> |
| class ShenandoahInitMarkRootsTask : public AbstractGangTask { |
| private: |
| ShenandoahAllRootScanner* _rp; |
| public: |
| ShenandoahInitMarkRootsTask(ShenandoahAllRootScanner* rp) : |
| AbstractGangTask("Shenandoah Init Mark Roots"), |
| _rp(rp) { |
| } |
| |
| void work(uint worker_id) { |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| ShenandoahParallelWorkerSession worker_session(worker_id); |
| |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| ShenandoahObjToScanQueueSet* queues = heap->concurrent_mark()->task_queues(); |
| assert(queues->get_reserved() > worker_id, "Queue has not been reserved for worker id: %d", worker_id); |
| |
| ShenandoahObjToScanQueue* q = queues->queue(worker_id); |
| |
| ShenandoahInitMarkRootsClosure<UPDATE_REFS> mark_cl(q); |
| do_work(heap, &mark_cl, worker_id); |
| } |
| |
| private: |
| void do_work(ShenandoahHeap* heap, OopClosure* oops, uint worker_id) { |
| // The rationale for selecting the roots to scan is as follows: |
| // a. With unload_classes = true, we only want to scan the actual strong roots from the |
| // code cache. This will allow us to identify the dead classes, unload them, *and* |
| // invalidate the relevant code cache blobs. This could be only done together with |
| // class unloading. |
| // b. With unload_classes = false, we have to nominally retain all the references from code |
| // cache, because there could be the case of embedded class/oop in the generated code, |
| // which we will never visit during mark. Without code cache invalidation, as in (a), |
| // we risk executing that code cache blob, and crashing. |
| if (heap->unload_classes()) { |
| _rp->strong_roots_do(worker_id, oops); |
| } else { |
| _rp->roots_do(worker_id, oops); |
| } |
| } |
| }; |
| |
| class ShenandoahUpdateRootsTask : public AbstractGangTask { |
| private: |
| ShenandoahRootUpdater* _root_updater; |
| public: |
| ShenandoahUpdateRootsTask(ShenandoahRootUpdater* root_updater) : |
| AbstractGangTask("Shenandoah Update Roots"), |
| _root_updater(root_updater) { |
| } |
| |
| void work(uint worker_id) { |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| ShenandoahParallelWorkerSession worker_session(worker_id); |
| |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| ShenandoahUpdateRefsClosure cl; |
| AlwaysTrueClosure always_true; |
| _root_updater->roots_do<AlwaysTrueClosure, ShenandoahUpdateRefsClosure>(worker_id, &always_true, &cl); |
| } |
| }; |
| |
| class ShenandoahConcurrentMarkingTask : public AbstractGangTask { |
| private: |
| ShenandoahConcurrentMark* _cm; |
| ShenandoahTaskTerminator* _terminator; |
| |
| public: |
| ShenandoahConcurrentMarkingTask(ShenandoahConcurrentMark* cm, ShenandoahTaskTerminator* terminator) : |
| AbstractGangTask("Shenandoah Concurrent Mark"), _cm(cm), _terminator(terminator) { |
| } |
| |
| void work(uint worker_id) { |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| ShenandoahConcurrentWorkerSession worker_session(worker_id); |
| ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); |
| ShenandoahObjToScanQueue* q = _cm->get_queue(worker_id); |
| ReferenceProcessor* rp; |
| if (heap->process_references()) { |
| rp = heap->ref_processor(); |
| shenandoah_assert_rp_isalive_installed(); |
| } else { |
| rp = NULL; |
| } |
| |
| _cm->concurrent_scan_code_roots(worker_id, rp); |
| _cm->mark_loop(worker_id, _terminator, rp, |
| true, // cancellable |
| ShenandoahStringDedup::is_enabled()); // perform string dedup |
| } |
| }; |
| |
| class ShenandoahSATBAndRemarkCodeRootsThreadsClosure : public ThreadClosure { |
| private: |
| ShenandoahConcMarkSATBBufferClosure* _satb_cl; |
| OopClosure* const _cl; |
| MarkingCodeBlobClosure* _code_cl; |
| int _thread_parity; |
| |
| public: |
| ShenandoahSATBAndRemarkCodeRootsThreadsClosure(ShenandoahConcMarkSATBBufferClosure* satb_cl, OopClosure* cl, MarkingCodeBlobClosure* code_cl) : |
| _satb_cl(satb_cl), _cl(cl), _code_cl(code_cl), |
| _thread_parity(Threads::thread_claim_parity()) {} |
| |
| void do_thread(Thread* thread) { |
| if (thread->is_Java_thread()) { |
| if (thread->claim_oops_do(true, _thread_parity)) { |
| JavaThread* jt = (JavaThread*)thread; |
| ShenandoahThreadLocalData::satb_mark_queue(jt).apply_closure_and_empty(_satb_cl); |
| if (_cl != NULL) { |
| ResourceMark rm; |
| jt->oops_do(_cl, _code_cl); |
| } else if (_code_cl != NULL) { |
| // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking |
| // however the liveness of oops reachable from nmethods have very complex lifecycles: |
| // * Alive if on the stack of an executing method |
| // * Weakly reachable otherwise |
| // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be |
| // live by the SATB invariant but other oops recorded in nmethods may behave differently. |
| jt->nmethods_do(_code_cl); |
| } |
| } |
| } else if (thread->is_VM_thread()) { |
| if (thread->claim_oops_do(true, _thread_parity)) { |
| ShenandoahBarrierSet::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(_satb_cl); |
| } |
| } |
| } |
| }; |
| |
| class ShenandoahFinalMarkingTask : public AbstractGangTask { |
| private: |
| ShenandoahConcurrentMark* _cm; |
| ShenandoahTaskTerminator* _terminator; |
| bool _dedup_string; |
| ShenandoahSharedFlag _claimed_syncroots; |
| |
| public: |
| ShenandoahFinalMarkingTask(ShenandoahConcurrentMark* cm, ShenandoahTaskTerminator* terminator, bool dedup_string) : |
| AbstractGangTask("Shenandoah Final Mark"), _cm(cm), _terminator(terminator), _dedup_string(dedup_string) { |
| } |
| |
| void work(uint worker_id) { |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| |
| ShenandoahParallelWorkerSession worker_session(worker_id); |
| ReferenceProcessor* rp; |
| if (heap->process_references()) { |
| rp = heap->ref_processor(); |
| shenandoah_assert_rp_isalive_installed(); |
| } else { |
| rp = NULL; |
| } |
| |
| // First drain remaining SATB buffers. |
| // Notice that this is not strictly necessary for mark-compact. But since |
| // it requires a StrongRootsScope around the task, we need to claim the |
| // threads, and performance-wise it doesn't really matter. Adds about 1ms to |
| // full-gc. |
| { |
| ShenandoahObjToScanQueue* q = _cm->get_queue(worker_id); |
| ShenandoahConcMarkSATBBufferClosure cl(q); |
| ShenandoahSATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set(); |
| while (satb_mq_set.apply_closure_to_completed_buffer(&cl)); |
| bool do_nmethods = heap->unload_classes(); |
| if (heap->has_forwarded_objects()) { |
| ShenandoahMarkResolveRefsClosure resolve_mark_cl(q, rp); |
| MarkingCodeBlobClosure blobsCl(&resolve_mark_cl, !CodeBlobToOopClosure::FixRelocations); |
| ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl, |
| ShenandoahIUBarrier ? &resolve_mark_cl : NULL, |
| do_nmethods ? &blobsCl : NULL); |
| Threads::threads_do(&tc); |
| if (ShenandoahIUBarrier && _claimed_syncroots.try_set()) { |
| ObjectSynchronizer::oops_do(&resolve_mark_cl); |
| } |
| } else { |
| ShenandoahMarkRefsClosure mark_cl(q, rp); |
| MarkingCodeBlobClosure blobsCl(&mark_cl, !CodeBlobToOopClosure::FixRelocations); |
| ShenandoahSATBAndRemarkCodeRootsThreadsClosure tc(&cl, |
| ShenandoahIUBarrier ? &mark_cl : NULL, |
| do_nmethods ? &blobsCl : NULL); |
| Threads::threads_do(&tc); |
| if (ShenandoahIUBarrier && _claimed_syncroots.try_set()) { |
| ObjectSynchronizer::oops_do(&mark_cl); |
| } |
| } |
| } |
| |
| if (heap->is_degenerated_gc_in_progress() || heap->is_full_gc_in_progress()) { |
| // Full GC does not execute concurrent cycle. |
| // Degenerated cycle may bypass concurrent cycle. |
| // So code roots might not be scanned, let's scan here. |
| _cm->concurrent_scan_code_roots(worker_id, rp); |
| } |
| |
| _cm->mark_loop(worker_id, _terminator, rp, |
| false, // not cancellable |
| _dedup_string); |
| |
| assert(_cm->task_queues()->is_empty(), "Should be empty"); |
| } |
| }; |
| |
| void ShenandoahConcurrentMark::mark_roots(ShenandoahPhaseTimings::Phase root_phase) { |
| assert(Thread::current()->is_VM_thread(), "can only do this in VMThread"); |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| |
| ShenandoahGCPhase phase(root_phase); |
| |
| WorkGang* workers = heap->workers(); |
| uint nworkers = workers->active_workers(); |
| |
| assert(nworkers <= task_queues()->size(), "Just check"); |
| |
| ShenandoahAllRootScanner root_proc(nworkers, root_phase); |
| TASKQUEUE_STATS_ONLY(task_queues()->reset_taskqueue_stats()); |
| task_queues()->reserve(nworkers); |
| |
| if (heap->has_forwarded_objects()) { |
| ShenandoahInitMarkRootsTask<RESOLVE> mark_roots(&root_proc); |
| workers->run_task(&mark_roots); |
| } else { |
| // No need to update references, which means the heap is stable. |
| // Can save time not walking through forwarding pointers. |
| ShenandoahInitMarkRootsTask<NONE> mark_roots(&root_proc); |
| workers->run_task(&mark_roots); |
| } |
| |
| clear_claim_codecache(); |
| } |
| |
| void ShenandoahConcurrentMark::update_roots(ShenandoahPhaseTimings::Phase root_phase) { |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| assert(root_phase == ShenandoahPhaseTimings::full_gc_update_roots || |
| root_phase == ShenandoahPhaseTimings::degen_gc_update_roots, |
| "Only for these phases"); |
| |
| ShenandoahGCPhase phase(root_phase); |
| |
| #if COMPILER2_OR_JVMCI |
| DerivedPointerTable::clear(); |
| #endif |
| |
| uint nworkers = _heap->workers()->active_workers(); |
| |
| ShenandoahRootUpdater root_updater(nworkers, root_phase); |
| ShenandoahUpdateRootsTask update_roots(&root_updater); |
| _heap->workers()->run_task(&update_roots); |
| |
| #if COMPILER2_OR_JVMCI |
| DerivedPointerTable::update_pointers(); |
| #endif |
| } |
| |
| class ShenandoahUpdateThreadRootsTask : public AbstractGangTask { |
| private: |
| ShenandoahThreadRoots _thread_roots; |
| ShenandoahPhaseTimings::Phase _phase; |
| ShenandoahGCWorkerPhase _worker_phase; |
| public: |
| ShenandoahUpdateThreadRootsTask(bool is_par, ShenandoahPhaseTimings::Phase phase) : |
| AbstractGangTask("Shenandoah Update Thread Roots"), |
| _thread_roots(phase, is_par), |
| _phase(phase), |
| _worker_phase(phase) {} |
| |
| void work(uint worker_id) { |
| ShenandoahUpdateRefsClosure cl; |
| _thread_roots.oops_do(&cl, NULL, worker_id); |
| } |
| }; |
| |
| void ShenandoahConcurrentMark::update_thread_roots(ShenandoahPhaseTimings::Phase root_phase) { |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| |
| ShenandoahGCPhase phase(root_phase); |
| |
| #if COMPILER2_OR_JVMCI |
| DerivedPointerTable::clear(); |
| #endif |
| |
| WorkGang* workers = _heap->workers(); |
| bool is_par = workers->active_workers() > 1; |
| |
| ShenandoahUpdateThreadRootsTask task(is_par, root_phase); |
| workers->run_task(&task); |
| |
| #if COMPILER2_OR_JVMCI |
| DerivedPointerTable::update_pointers(); |
| #endif |
| } |
| |
| void ShenandoahConcurrentMark::initialize(uint workers) { |
| _heap = ShenandoahHeap::heap(); |
| |
| uint num_queues = MAX2(workers, 1U); |
| |
| _task_queues = new ShenandoahObjToScanQueueSet((int) num_queues); |
| |
| for (uint i = 0; i < num_queues; ++i) { |
| ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue(); |
| task_queue->initialize(); |
| _task_queues->register_queue(i, task_queue); |
| } |
| |
| ShenandoahBarrierSet::satb_mark_queue_set().set_buffer_size(ShenandoahSATBBufferSize); |
| } |
| |
| void ShenandoahConcurrentMark::concurrent_scan_code_roots(uint worker_id, ReferenceProcessor* rp) { |
| if (_heap->unload_classes()) { |
| return; |
| } |
| |
| if (claim_codecache()) { |
| ShenandoahObjToScanQueue* q = task_queues()->queue(worker_id); |
| MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| // TODO: We can not honor StringDeduplication here, due to lock ranking |
| // inversion. So, we may miss some deduplication candidates. |
| if (_heap->has_forwarded_objects()) { |
| ShenandoahMarkResolveRefsClosure cl(q, rp); |
| CodeBlobToOopClosure blobs(&cl, !CodeBlobToOopClosure::FixRelocations); |
| CodeCache::blobs_do(&blobs); |
| } else { |
| ShenandoahMarkRefsClosure cl(q, rp); |
| CodeBlobToOopClosure blobs(&cl, !CodeBlobToOopClosure::FixRelocations); |
| CodeCache::blobs_do(&blobs); |
| } |
| } |
| } |
| |
| class ShenandoahFlushSATBHandshakeClosure : public HandshakeClosure { |
| public: |
| ShenandoahFlushSATBHandshakeClosure() : |
| HandshakeClosure("Shenandoah Flush SATB Handshake") {} |
| |
| void do_thread(Thread* thread) { |
| ShenandoahThreadLocalData::satb_mark_queue(thread).flush(); |
| } |
| }; |
| |
| void ShenandoahConcurrentMark::mark_from_roots() { |
| WorkGang* workers = _heap->workers(); |
| uint nworkers = workers->active_workers(); |
| |
| if (_heap->process_references()) { |
| ReferenceProcessor* rp = _heap->ref_processor(); |
| rp->set_active_mt_degree(nworkers); |
| |
| // enable ("weak") refs discovery |
| rp->enable_discovery(true /*verify_no_refs*/); |
| rp->setup_policy(_heap->soft_ref_policy()->should_clear_all_soft_refs()); |
| } |
| |
| shenandoah_assert_rp_isalive_not_installed(); |
| ShenandoahIsAliveSelector is_alive; |
| ReferenceProcessorIsAliveMutator fix_isalive(_heap->ref_processor(), is_alive.is_alive_closure()); |
| |
| task_queues()->reserve(nworkers); |
| |
| ShenandoahSATBMarkQueueSet& qset = ShenandoahBarrierSet::satb_mark_queue_set(); |
| ShenandoahFlushSATBHandshakeClosure flush_satb; |
| for (uint flushes = 0; flushes < ShenandoahMaxSATBBufferFlushes; flushes++) { |
| ShenandoahTaskTerminator terminator(nworkers, task_queues()); |
| ShenandoahConcurrentMarkingTask task(this, &terminator); |
| workers->run_task(&task); |
| |
| if (_heap->cancelled_gc()) { |
| // GC is cancelled, break out. |
| break; |
| } |
| |
| size_t before = qset.completed_buffers_num(); |
| Handshake::execute(&flush_satb); |
| size_t after = qset.completed_buffers_num(); |
| |
| if (before == after) { |
| // No more retries needed, break out. |
| break; |
| } |
| } |
| |
| assert(task_queues()->is_empty() || _heap->cancelled_gc(), "Should be empty when not cancelled"); |
| } |
| |
| void ShenandoahConcurrentMark::finish_mark_from_roots(bool full_gc) { |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| |
| uint nworkers = _heap->workers()->active_workers(); |
| |
| // Finally mark everything else we've got in our queues during the previous steps. |
| // It does two different things for concurrent vs. mark-compact GC: |
| // - For concurrent GC, it starts with empty task queues, drains the remaining |
| // SATB buffers, and then completes the marking closure. |
| // - For mark-compact GC, it starts out with the task queues seeded by initial |
| // root scan, and completes the closure, thus marking through all live objects |
| // The implementation is the same, so it's shared here. |
| { |
| ShenandoahGCPhase phase(full_gc ? |
| ShenandoahPhaseTimings::full_gc_mark_finish_queues : |
| ShenandoahPhaseTimings::finish_queues); |
| task_queues()->reserve(nworkers); |
| |
| shenandoah_assert_rp_isalive_not_installed(); |
| ShenandoahIsAliveSelector is_alive; |
| ReferenceProcessorIsAliveMutator fix_isalive(_heap->ref_processor(), is_alive.is_alive_closure()); |
| |
| StrongRootsScope scope(nworkers); |
| ShenandoahTaskTerminator terminator(nworkers, task_queues()); |
| ShenandoahFinalMarkingTask task(this, &terminator, ShenandoahStringDedup::is_enabled()); |
| _heap->workers()->run_task(&task); |
| } |
| |
| assert(task_queues()->is_empty(), "Should be empty"); |
| |
| // When we're done marking everything, we process weak references. |
| if (_heap->process_references()) { |
| weak_refs_work(full_gc); |
| } |
| } |
| |
| // Weak Reference Closures |
| class ShenandoahCMDrainMarkingStackClosure: public VoidClosure { |
| uint _worker_id; |
| ShenandoahTaskTerminator* _terminator; |
| bool _reset_terminator; |
| |
| public: |
| ShenandoahCMDrainMarkingStackClosure(uint worker_id, ShenandoahTaskTerminator* t, bool reset_terminator = false): |
| _worker_id(worker_id), |
| _terminator(t), |
| _reset_terminator(reset_terminator) { |
| } |
| |
| void do_void() { |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| |
| ShenandoahHeap* sh = ShenandoahHeap::heap(); |
| ShenandoahConcurrentMark* scm = sh->concurrent_mark(); |
| assert(sh->process_references(), "why else would we be here?"); |
| ReferenceProcessor* rp = sh->ref_processor(); |
| |
| shenandoah_assert_rp_isalive_installed(); |
| |
| scm->mark_loop(_worker_id, _terminator, rp, |
| false, // not cancellable |
| false); // do not do strdedup |
| |
| if (_reset_terminator) { |
| _terminator->reset_for_reuse(); |
| } |
| } |
| }; |
| |
| class ShenandoahCMKeepAliveClosure : public OopClosure { |
| private: |
| ShenandoahObjToScanQueue* _queue; |
| ShenandoahHeap* _heap; |
| ShenandoahMarkingContext* const _mark_context; |
| |
| template <class T> |
| inline void do_oop_work(T* p) { |
| ShenandoahConcurrentMark::mark_through_ref<T, NONE, NO_DEDUP>(p, _heap, _queue, _mark_context); |
| } |
| |
| public: |
| ShenandoahCMKeepAliveClosure(ShenandoahObjToScanQueue* q) : |
| _queue(q), |
| _heap(ShenandoahHeap::heap()), |
| _mark_context(_heap->marking_context()) {} |
| |
| void do_oop(narrowOop* p) { do_oop_work(p); } |
| void do_oop(oop* p) { do_oop_work(p); } |
| }; |
| |
| class ShenandoahCMKeepAliveUpdateClosure : public OopClosure { |
| private: |
| ShenandoahObjToScanQueue* _queue; |
| ShenandoahHeap* _heap; |
| ShenandoahMarkingContext* const _mark_context; |
| |
| template <class T> |
| inline void do_oop_work(T* p) { |
| ShenandoahConcurrentMark::mark_through_ref<T, SIMPLE, NO_DEDUP>(p, _heap, _queue, _mark_context); |
| } |
| |
| public: |
| ShenandoahCMKeepAliveUpdateClosure(ShenandoahObjToScanQueue* q) : |
| _queue(q), |
| _heap(ShenandoahHeap::heap()), |
| _mark_context(_heap->marking_context()) {} |
| |
| void do_oop(narrowOop* p) { do_oop_work(p); } |
| void do_oop(oop* p) { do_oop_work(p); } |
| }; |
| |
| class ShenandoahWeakUpdateClosure : public OopClosure { |
| private: |
| ShenandoahHeap* const _heap; |
| |
| template <class T> |
| inline void do_oop_work(T* p) { |
| oop o = _heap->maybe_update_with_forwarded(p); |
| shenandoah_assert_marked_except(p, o, o == NULL); |
| } |
| |
| public: |
| ShenandoahWeakUpdateClosure() : _heap(ShenandoahHeap::heap()) {} |
| |
| void do_oop(narrowOop* p) { do_oop_work(p); } |
| void do_oop(oop* p) { do_oop_work(p); } |
| }; |
| |
| class ShenandoahRefProcTaskProxy : public AbstractGangTask { |
| private: |
| AbstractRefProcTaskExecutor::ProcessTask& _proc_task; |
| ShenandoahTaskTerminator* _terminator; |
| |
| public: |
| ShenandoahRefProcTaskProxy(AbstractRefProcTaskExecutor::ProcessTask& proc_task, |
| ShenandoahTaskTerminator* t) : |
| AbstractGangTask("Shenandoah Process Weak References"), |
| _proc_task(proc_task), |
| _terminator(t) { |
| } |
| |
| void work(uint worker_id) { |
| ResourceMark rm; |
| HandleMark hm; |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| ShenandoahCMDrainMarkingStackClosure complete_gc(worker_id, _terminator); |
| if (heap->has_forwarded_objects()) { |
| ShenandoahForwardedIsAliveClosure is_alive; |
| ShenandoahCMKeepAliveUpdateClosure keep_alive(heap->concurrent_mark()->get_queue(worker_id)); |
| _proc_task.work(worker_id, is_alive, keep_alive, complete_gc); |
| } else { |
| ShenandoahIsAliveClosure is_alive; |
| ShenandoahCMKeepAliveClosure keep_alive(heap->concurrent_mark()->get_queue(worker_id)); |
| _proc_task.work(worker_id, is_alive, keep_alive, complete_gc); |
| } |
| } |
| }; |
| |
| class ShenandoahRefProcTaskExecutor : public AbstractRefProcTaskExecutor { |
| private: |
| WorkGang* _workers; |
| |
| public: |
| ShenandoahRefProcTaskExecutor(WorkGang* workers) : |
| _workers(workers) { |
| } |
| |
| // Executes a task using worker threads. |
| void execute(ProcessTask& task, uint ergo_workers) { |
| assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint"); |
| |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| ShenandoahConcurrentMark* cm = heap->concurrent_mark(); |
| ShenandoahPushWorkerQueuesScope scope(_workers, cm->task_queues(), |
| ergo_workers, |
| /* do_check = */ false); |
| uint nworkers = _workers->active_workers(); |
| cm->task_queues()->reserve(nworkers); |
| ShenandoahTaskTerminator terminator(nworkers, cm->task_queues()); |
| ShenandoahRefProcTaskProxy proc_task_proxy(task, &terminator); |
| _workers->run_task(&proc_task_proxy); |
| } |
| }; |
| |
| void ShenandoahConcurrentMark::weak_refs_work(bool full_gc) { |
| assert(_heap->process_references(), "sanity"); |
| |
| ShenandoahPhaseTimings::Phase phase_root = |
| full_gc ? |
| ShenandoahPhaseTimings::full_gc_weakrefs : |
| ShenandoahPhaseTimings::weakrefs; |
| |
| ShenandoahGCPhase phase(phase_root); |
| |
| ReferenceProcessor* rp = _heap->ref_processor(); |
| |
| // NOTE: We cannot shortcut on has_discovered_references() here, because |
| // we will miss marking JNI Weak refs then, see implementation in |
| // ReferenceProcessor::process_discovered_references. |
| weak_refs_work_doit(full_gc); |
| |
| rp->verify_no_references_recorded(); |
| assert(!rp->discovery_enabled(), "Post condition"); |
| |
| } |
| |
| void ShenandoahConcurrentMark::weak_refs_work_doit(bool full_gc) { |
| ReferenceProcessor* rp = _heap->ref_processor(); |
| |
| ShenandoahPhaseTimings::Phase phase_process = |
| full_gc ? |
| ShenandoahPhaseTimings::full_gc_weakrefs_process : |
| ShenandoahPhaseTimings::weakrefs_process; |
| |
| shenandoah_assert_rp_isalive_not_installed(); |
| ShenandoahIsAliveSelector is_alive; |
| ReferenceProcessorIsAliveMutator fix_isalive(rp, is_alive.is_alive_closure()); |
| |
| WorkGang* workers = _heap->workers(); |
| uint nworkers = workers->active_workers(); |
| |
| rp->setup_policy(_heap->soft_ref_policy()->should_clear_all_soft_refs()); |
| rp->set_active_mt_degree(nworkers); |
| |
| assert(task_queues()->is_empty(), "Should be empty"); |
| |
| // complete_gc and keep_alive closures instantiated here are only needed for |
| // single-threaded path in RP. They share the queue 0 for tracking work, which |
| // simplifies implementation. Since RP may decide to call complete_gc several |
| // times, we need to be able to reuse the terminator. |
| uint serial_worker_id = 0; |
| ShenandoahTaskTerminator terminator(1, task_queues()); |
| ShenandoahCMDrainMarkingStackClosure complete_gc(serial_worker_id, &terminator, /* reset_terminator = */ true); |
| |
| ShenandoahRefProcTaskExecutor executor(workers); |
| |
| ReferenceProcessorPhaseTimes pt(_heap->gc_timer(), rp->num_queues()); |
| |
| { |
| ShenandoahGCPhase phase(phase_process); |
| |
| if (_heap->has_forwarded_objects()) { |
| ShenandoahCMKeepAliveUpdateClosure keep_alive(get_queue(serial_worker_id)); |
| const ReferenceProcessorStats& stats = |
| rp->process_discovered_references(is_alive.is_alive_closure(), &keep_alive, |
| &complete_gc, &executor, |
| &pt); |
| _heap->tracer()->report_gc_reference_stats(stats); |
| } else { |
| ShenandoahCMKeepAliveClosure keep_alive(get_queue(serial_worker_id)); |
| const ReferenceProcessorStats& stats = |
| rp->process_discovered_references(is_alive.is_alive_closure(), &keep_alive, |
| &complete_gc, &executor, |
| &pt); |
| _heap->tracer()->report_gc_reference_stats(stats); |
| } |
| |
| pt.print_all_references(); |
| |
| assert(task_queues()->is_empty(), "Should be empty"); |
| } |
| } |
| |
| class ShenandoahCancelledGCYieldClosure : public YieldClosure { |
| private: |
| ShenandoahHeap* const _heap; |
| public: |
| ShenandoahCancelledGCYieldClosure() : _heap(ShenandoahHeap::heap()) {}; |
| virtual bool should_return() { return _heap->cancelled_gc(); } |
| }; |
| |
| class ShenandoahPrecleanCompleteGCClosure : public VoidClosure { |
| public: |
| void do_void() { |
| ShenandoahHeap* sh = ShenandoahHeap::heap(); |
| ShenandoahConcurrentMark* scm = sh->concurrent_mark(); |
| assert(sh->process_references(), "why else would we be here?"); |
| ShenandoahTaskTerminator terminator(1, scm->task_queues()); |
| |
| ReferenceProcessor* rp = sh->ref_processor(); |
| shenandoah_assert_rp_isalive_installed(); |
| |
| scm->mark_loop(0, &terminator, rp, |
| false, // not cancellable |
| false); // do not do strdedup |
| } |
| }; |
| |
| class ShenandoahPrecleanTask : public AbstractGangTask { |
| private: |
| ReferenceProcessor* _rp; |
| |
| public: |
| ShenandoahPrecleanTask(ReferenceProcessor* rp) : |
| AbstractGangTask("Shenandoah Precleaning"), |
| _rp(rp) {} |
| |
| void work(uint worker_id) { |
| assert(worker_id == 0, "The code below is single-threaded, only one worker is expected"); |
| ShenandoahParallelWorkerSession worker_session(worker_id); |
| |
| ShenandoahHeap* sh = ShenandoahHeap::heap(); |
| assert(!sh->has_forwarded_objects(), "No forwarded objects expected here"); |
| |
| ShenandoahObjToScanQueue* q = sh->concurrent_mark()->get_queue(worker_id); |
| |
| ShenandoahCancelledGCYieldClosure yield; |
| ShenandoahPrecleanCompleteGCClosure complete_gc; |
| |
| ShenandoahIsAliveClosure is_alive; |
| ShenandoahCMKeepAliveClosure keep_alive(q); |
| ResourceMark rm; |
| _rp->preclean_discovered_references(&is_alive, &keep_alive, |
| &complete_gc, &yield, |
| NULL); |
| } |
| }; |
| |
| void ShenandoahConcurrentMark::preclean_weak_refs() { |
| // Pre-cleaning weak references before diving into STW makes sense at the |
| // end of concurrent mark. This will filter out the references which referents |
| // are alive. Note that ReferenceProcessor already filters out these on reference |
| // discovery, and the bulk of work is done here. This phase processes leftovers |
| // that missed the initial filtering, i.e. when referent was marked alive after |
| // reference was discovered by RP. |
| |
| assert(_heap->process_references(), "sanity"); |
| |
| // Shortcut if no references were discovered to avoid winding up threads. |
| ReferenceProcessor* rp = _heap->ref_processor(); |
| if (!rp->has_discovered_references()) { |
| return; |
| } |
| |
| assert(task_queues()->is_empty(), "Should be empty"); |
| |
| ReferenceProcessorMTDiscoveryMutator fix_mt_discovery(rp, false); |
| |
| shenandoah_assert_rp_isalive_not_installed(); |
| ShenandoahIsAliveSelector is_alive; |
| ReferenceProcessorIsAliveMutator fix_isalive(rp, is_alive.is_alive_closure()); |
| |
| // Execute precleaning in the worker thread: it will give us GCLABs, String dedup |
| // queues and other goodies. When upstream ReferenceProcessor starts supporting |
| // parallel precleans, we can extend this to more threads. |
| WorkGang* workers = _heap->workers(); |
| uint nworkers = workers->active_workers(); |
| assert(nworkers == 1, "This code uses only a single worker"); |
| task_queues()->reserve(nworkers); |
| |
| ShenandoahPrecleanTask task(rp); |
| workers->run_task(&task); |
| |
| assert(task_queues()->is_empty(), "Should be empty"); |
| } |
| |
| void ShenandoahConcurrentMark::cancel() { |
| // Clean up marking stacks. |
| ShenandoahObjToScanQueueSet* queues = task_queues(); |
| queues->clear(); |
| |
| // Cancel SATB buffers. |
| ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking(); |
| } |
| |
| ShenandoahObjToScanQueue* ShenandoahConcurrentMark::get_queue(uint worker_id) { |
| assert(task_queues()->get_reserved() > worker_id, "No reserved queue for worker id: %d", worker_id); |
| return _task_queues->queue(worker_id); |
| } |
| |
| template <bool CANCELLABLE> |
| void ShenandoahConcurrentMark::mark_loop_prework(uint w, ShenandoahTaskTerminator *t, ReferenceProcessor *rp, |
| bool strdedup) { |
| ShenandoahObjToScanQueue* q = get_queue(w); |
| |
| ShenandoahLiveData* ld = _heap->get_liveness_cache(w); |
| |
| // TODO: We can clean up this if we figure out how to do templated oop closures that |
| // play nice with specialized_oop_iterators. |
| if (_heap->unload_classes()) { |
| if (_heap->has_forwarded_objects()) { |
| if (strdedup) { |
| ShenandoahMarkUpdateRefsMetadataDedupClosure cl(q, rp); |
| mark_loop_work<ShenandoahMarkUpdateRefsMetadataDedupClosure, CANCELLABLE>(&cl, ld, w, t); |
| } else { |
| ShenandoahMarkUpdateRefsMetadataClosure cl(q, rp); |
| mark_loop_work<ShenandoahMarkUpdateRefsMetadataClosure, CANCELLABLE>(&cl, ld, w, t); |
| } |
| } else { |
| if (strdedup) { |
| ShenandoahMarkRefsMetadataDedupClosure cl(q, rp); |
| mark_loop_work<ShenandoahMarkRefsMetadataDedupClosure, CANCELLABLE>(&cl, ld, w, t); |
| } else { |
| ShenandoahMarkRefsMetadataClosure cl(q, rp); |
| mark_loop_work<ShenandoahMarkRefsMetadataClosure, CANCELLABLE>(&cl, ld, w, t); |
| } |
| } |
| } else { |
| if (_heap->has_forwarded_objects()) { |
| if (strdedup) { |
| ShenandoahMarkUpdateRefsDedupClosure cl(q, rp); |
| mark_loop_work<ShenandoahMarkUpdateRefsDedupClosure, CANCELLABLE>(&cl, ld, w, t); |
| } else { |
| ShenandoahMarkUpdateRefsClosure cl(q, rp); |
| mark_loop_work<ShenandoahMarkUpdateRefsClosure, CANCELLABLE>(&cl, ld, w, t); |
| } |
| } else { |
| if (strdedup) { |
| ShenandoahMarkRefsDedupClosure cl(q, rp); |
| mark_loop_work<ShenandoahMarkRefsDedupClosure, CANCELLABLE>(&cl, ld, w, t); |
| } else { |
| ShenandoahMarkRefsClosure cl(q, rp); |
| mark_loop_work<ShenandoahMarkRefsClosure, CANCELLABLE>(&cl, ld, w, t); |
| } |
| } |
| } |
| |
| _heap->flush_liveness_cache(w); |
| } |
| |
| template <class T, bool CANCELLABLE> |
| void ShenandoahConcurrentMark::mark_loop_work(T* cl, ShenandoahLiveData* live_data, uint worker_id, ShenandoahTaskTerminator *terminator) { |
| int seed = 17; |
| uintx stride = ShenandoahMarkLoopStride; |
| |
| ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| ShenandoahObjToScanQueueSet* queues = task_queues(); |
| ShenandoahObjToScanQueue* q; |
| ShenandoahMarkTask t; |
| |
| /* |
| * Process outstanding queues, if any. |
| * |
| * There can be more queues than workers. To deal with the imbalance, we claim |
| * extra queues first. Since marking can push new tasks into the queue associated |
| * with this worker id, we come back to process this queue in the normal loop. |
| */ |
| assert(queues->get_reserved() == heap->workers()->active_workers(), |
| "Need to reserve proper number of queues: reserved: %u, active: %u", queues->get_reserved(), heap->workers()->active_workers()); |
| |
| q = queues->claim_next(); |
| while (q != NULL) { |
| if (CANCELLABLE && heap->check_cancelled_gc_and_yield()) { |
| return; |
| } |
| |
| for (uint i = 0; i < stride; i++) { |
| if (q->pop(t)) { |
| do_task<T>(q, cl, live_data, &t); |
| } else { |
| assert(q->is_empty(), "Must be empty"); |
| q = queues->claim_next(); |
| break; |
| } |
| } |
| } |
| q = get_queue(worker_id); |
| |
| ShenandoahConcMarkSATBBufferClosure drain_satb(q); |
| ShenandoahSATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set(); |
| |
| /* |
| * Normal marking loop: |
| */ |
| while (true) { |
| if (CANCELLABLE && heap->check_cancelled_gc_and_yield()) { |
| return; |
| } |
| |
| while (satb_mq_set.completed_buffers_num() > 0) { |
| satb_mq_set.apply_closure_to_completed_buffer(&drain_satb); |
| } |
| |
| uint work = 0; |
| for (uint i = 0; i < stride; i++) { |
| if (q->pop(t) || |
| queues->steal(worker_id, &seed, t)) { |
| do_task<T>(q, cl, live_data, &t); |
| work++; |
| } else { |
| break; |
| } |
| } |
| |
| if (work == 0) { |
| // No work encountered in current stride, try to terminate. |
| // Need to leave the STS here otherwise it might block safepoints. |
| ShenandoahSuspendibleThreadSetLeaver stsl(CANCELLABLE && ShenandoahSuspendibleWorkers); |
| ShenandoahTerminatorTerminator tt(heap); |
| if (terminator->offer_termination(&tt)) return; |
| } |
| } |
| } |
| |
| bool ShenandoahConcurrentMark::claim_codecache() { |
| return _claimed_codecache.try_set(); |
| } |
| |
| void ShenandoahConcurrentMark::clear_claim_codecache() { |
| _claimed_codecache.unset(); |
| } |