| /* |
| * Copyright (c) 2001, 2017, 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/classLoaderData.hpp" |
| #include "gc/g1/concurrentMarkThread.inline.hpp" |
| #include "gc/g1/g1Analytics.hpp" |
| #include "gc/g1/g1CollectedHeap.inline.hpp" |
| #include "gc/g1/g1ConcurrentMark.inline.hpp" |
| #include "gc/g1/g1MMUTracker.hpp" |
| #include "gc/g1/g1Policy.hpp" |
| #include "gc/g1/suspendibleThreadSet.hpp" |
| #include "gc/g1/vm_operations_g1.hpp" |
| #include "gc/shared/concurrentGCPhaseManager.hpp" |
| #include "gc/shared/gcId.hpp" |
| #include "gc/shared/gcTrace.hpp" |
| #include "gc/shared/gcTraceTime.inline.hpp" |
| #include "logging/log.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "runtime/vmThread.hpp" |
| #include "utilities/debug.hpp" |
| |
| // ======= Concurrent Mark Thread ======== |
| |
| // Check order in EXPAND_CURRENT_PHASES |
| STATIC_ASSERT(ConcurrentGCPhaseManager::UNCONSTRAINED_PHASE < |
| ConcurrentGCPhaseManager::IDLE_PHASE); |
| |
| #define EXPAND_CONCURRENT_PHASES(expander) \ |
| expander(ANY, = ConcurrentGCPhaseManager::UNCONSTRAINED_PHASE, NULL) \ |
| expander(IDLE, = ConcurrentGCPhaseManager::IDLE_PHASE, NULL) \ |
| expander(CONCURRENT_CYCLE,, "Concurrent Cycle") \ |
| expander(CLEAR_CLAIMED_MARKS,, "Concurrent Clear Claimed Marks") \ |
| expander(SCAN_ROOT_REGIONS,, "Concurrent Scan Root Regions") \ |
| expander(CONCURRENT_MARK,, "Concurrent Mark") \ |
| expander(MARK_FROM_ROOTS,, "Concurrent Mark From Roots") \ |
| expander(BEFORE_REMARK,, NULL) \ |
| expander(REMARK,, NULL) \ |
| expander(CREATE_LIVE_DATA,, "Concurrent Create Live Data") \ |
| expander(COMPLETE_CLEANUP,, "Concurrent Complete Cleanup") \ |
| expander(CLEANUP_FOR_NEXT_MARK,, "Concurrent Cleanup for Next Mark") \ |
| /* */ |
| |
| class G1ConcurrentPhase : public AllStatic { |
| public: |
| enum { |
| #define CONCURRENT_PHASE_ENUM(tag, value, ignore_title) tag value, |
| EXPAND_CONCURRENT_PHASES(CONCURRENT_PHASE_ENUM) |
| #undef CONCURRENT_PHASE_ENUM |
| PHASE_ID_LIMIT |
| }; |
| }; |
| |
| // The CM thread is created when the G1 garbage collector is used |
| |
| ConcurrentMarkThread::ConcurrentMarkThread(G1ConcurrentMark* cm) : |
| ConcurrentGCThread(), |
| _cm(cm), |
| _state(Idle), |
| _phase_manager_stack(), |
| _vtime_accum(0.0), |
| _vtime_mark_accum(0.0) { |
| |
| set_name("G1 Main Marker"); |
| create_and_start(); |
| } |
| |
| class CMCheckpointRootsFinalClosure: public VoidClosure { |
| |
| G1ConcurrentMark* _cm; |
| public: |
| |
| CMCheckpointRootsFinalClosure(G1ConcurrentMark* cm) : |
| _cm(cm) {} |
| |
| void do_void(){ |
| _cm->checkpointRootsFinal(false); // !clear_all_soft_refs |
| } |
| }; |
| |
| class CMCleanUp: public VoidClosure { |
| G1ConcurrentMark* _cm; |
| public: |
| |
| CMCleanUp(G1ConcurrentMark* cm) : |
| _cm(cm) {} |
| |
| void do_void(){ |
| _cm->cleanup(); |
| } |
| }; |
| |
| // Marking pauses can be scheduled flexibly, so we might delay marking to meet MMU. |
| void ConcurrentMarkThread::delay_to_keep_mmu(G1Policy* g1_policy, bool remark) { |
| const G1Analytics* analytics = g1_policy->analytics(); |
| if (g1_policy->adaptive_young_list_length()) { |
| double now = os::elapsedTime(); |
| double prediction_ms = remark ? analytics->predict_remark_time_ms() |
| : analytics->predict_cleanup_time_ms(); |
| G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker(); |
| jlong sleep_time_ms = mmu_tracker->when_ms(now, prediction_ms); |
| os::sleep(this, sleep_time_ms, false); |
| } |
| } |
| |
| class G1ConcPhaseTimer : public GCTraceConcTimeImpl<LogLevel::Info, LOG_TAGS(gc, marking)> { |
| G1ConcurrentMark* _cm; |
| |
| public: |
| G1ConcPhaseTimer(G1ConcurrentMark* cm, const char* title) : |
| GCTraceConcTimeImpl<LogLevel::Info, LogTag::_gc, LogTag::_marking>(title), |
| _cm(cm) |
| { |
| _cm->gc_timer_cm()->register_gc_concurrent_start(title); |
| } |
| |
| ~G1ConcPhaseTimer() { |
| _cm->gc_timer_cm()->register_gc_concurrent_end(); |
| } |
| }; |
| |
| static const char* const concurrent_phase_names[] = { |
| #define CONCURRENT_PHASE_NAME(tag, ignore_value, ignore_title) XSTR(tag), |
| EXPAND_CONCURRENT_PHASES(CONCURRENT_PHASE_NAME) |
| #undef CONCURRENT_PHASE_NAME |
| NULL // terminator |
| }; |
| // Verify dense enum assumption. +1 for terminator. |
| STATIC_ASSERT(G1ConcurrentPhase::PHASE_ID_LIMIT + 1 == |
| ARRAY_SIZE(concurrent_phase_names)); |
| |
| // Returns the phase number for name, or a negative value if unknown. |
| static int lookup_concurrent_phase(const char* name) { |
| const char* const* names = concurrent_phase_names; |
| for (uint i = 0; names[i] != NULL; ++i) { |
| if (strcmp(name, names[i]) == 0) { |
| return static_cast<int>(i); |
| } |
| } |
| return -1; |
| } |
| |
| // The phase must be valid and must have a title. |
| static const char* lookup_concurrent_phase_title(int phase) { |
| static const char* const titles[] = { |
| #define CONCURRENT_PHASE_TITLE(ignore_tag, ignore_value, title) title, |
| EXPAND_CONCURRENT_PHASES(CONCURRENT_PHASE_TITLE) |
| #undef CONCURRENT_PHASE_TITLE |
| }; |
| // Verify dense enum assumption. |
| STATIC_ASSERT(G1ConcurrentPhase::PHASE_ID_LIMIT == ARRAY_SIZE(titles)); |
| |
| assert(0 <= phase, "precondition"); |
| assert((uint)phase < ARRAY_SIZE(titles), "precondition"); |
| const char* title = titles[phase]; |
| assert(title != NULL, "precondition"); |
| return title; |
| } |
| |
| class G1ConcPhaseManager : public StackObj { |
| G1ConcurrentMark* _cm; |
| ConcurrentGCPhaseManager _manager; |
| |
| public: |
| G1ConcPhaseManager(int phase, ConcurrentMarkThread* thread) : |
| _cm(thread->cm()), |
| _manager(phase, thread->phase_manager_stack()) |
| { } |
| |
| ~G1ConcPhaseManager() { |
| // Deactivate the manager if marking aborted, to avoid blocking on |
| // phase exit when the phase has been requested. |
| if (_cm->has_aborted()) { |
| _manager.deactivate(); |
| } |
| } |
| |
| void set_phase(int phase, bool force) { |
| _manager.set_phase(phase, force); |
| } |
| }; |
| |
| // Combine phase management and timing into one convenient utility. |
| class G1ConcPhase : public StackObj { |
| G1ConcPhaseTimer _timer; |
| G1ConcPhaseManager _manager; |
| |
| public: |
| G1ConcPhase(int phase, ConcurrentMarkThread* thread) : |
| _timer(thread->cm(), lookup_concurrent_phase_title(phase)), |
| _manager(phase, thread) |
| { } |
| }; |
| |
| const char* const* ConcurrentMarkThread::concurrent_phases() const { |
| return concurrent_phase_names; |
| } |
| |
| bool ConcurrentMarkThread::request_concurrent_phase(const char* phase_name) { |
| int phase = lookup_concurrent_phase(phase_name); |
| if (phase < 0) return false; |
| |
| while (!ConcurrentGCPhaseManager::wait_for_phase(phase, |
| phase_manager_stack())) { |
| assert(phase != G1ConcurrentPhase::ANY, "Wait for ANY phase must succeed"); |
| if ((phase != G1ConcurrentPhase::IDLE) && !during_cycle()) { |
| // If idle and the goal is !idle, start a collection. |
| G1CollectedHeap::heap()->collect(GCCause::_wb_conc_mark); |
| } |
| } |
| return true; |
| } |
| |
| void ConcurrentMarkThread::run_service() { |
| _vtime_start = os::elapsedVTime(); |
| |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| G1Policy* g1_policy = g1h->g1_policy(); |
| |
| G1ConcPhaseManager cpmanager(G1ConcurrentPhase::IDLE, this); |
| |
| while (!should_terminate()) { |
| // wait until started is set. |
| sleepBeforeNextCycle(); |
| if (should_terminate()) { |
| break; |
| } |
| |
| cpmanager.set_phase(G1ConcurrentPhase::CONCURRENT_CYCLE, false /* force */); |
| |
| GCIdMark gc_id_mark; |
| |
| cm()->concurrent_cycle_start(); |
| |
| assert(GCId::current() != GCId::undefined(), "GC id should have been set up by the initial mark GC."); |
| |
| GCTraceConcTime(Info, gc) tt("Concurrent Cycle"); |
| { |
| ResourceMark rm; |
| HandleMark hm; |
| double cycle_start = os::elapsedVTime(); |
| |
| { |
| G1ConcPhase p(G1ConcurrentPhase::CLEAR_CLAIMED_MARKS, this); |
| ClassLoaderDataGraph::clear_claimed_marks(); |
| } |
| |
| // We have to ensure that we finish scanning the root regions |
| // before the next GC takes place. To ensure this we have to |
| // make sure that we do not join the STS until the root regions |
| // have been scanned. If we did then it's possible that a |
| // subsequent GC could block us from joining the STS and proceed |
| // without the root regions have been scanned which would be a |
| // correctness issue. |
| |
| { |
| G1ConcPhase p(G1ConcurrentPhase::SCAN_ROOT_REGIONS, this); |
| _cm->scan_root_regions(); |
| } |
| |
| // It would be nice to use the G1ConcPhase class here but |
| // the "end" logging is inside the loop and not at the end of |
| // a scope. Also, the timer doesn't support nesting. |
| // Mimicking the same log output instead. |
| { |
| G1ConcPhaseManager mark_manager(G1ConcurrentPhase::CONCURRENT_MARK, this); |
| jlong mark_start = os::elapsed_counter(); |
| const char* cm_title = |
| lookup_concurrent_phase_title(G1ConcurrentPhase::CONCURRENT_MARK); |
| log_info(gc, marking)("%s (%.3fs)", |
| cm_title, |
| TimeHelper::counter_to_seconds(mark_start)); |
| for (uint iter = 1; !cm()->has_aborted(); ++iter) { |
| // Concurrent marking. |
| { |
| G1ConcPhase p(G1ConcurrentPhase::MARK_FROM_ROOTS, this); |
| _cm->mark_from_roots(); |
| } |
| if (cm()->has_aborted()) break; |
| |
| // Provide a control point after mark_from_roots. |
| { |
| G1ConcPhaseManager p(G1ConcurrentPhase::BEFORE_REMARK, this); |
| } |
| if (cm()->has_aborted()) break; |
| |
| // Delay remark pause for MMU. |
| double mark_end_time = os::elapsedVTime(); |
| jlong mark_end = os::elapsed_counter(); |
| _vtime_mark_accum += (mark_end_time - cycle_start); |
| delay_to_keep_mmu(g1_policy, true /* remark */); |
| if (cm()->has_aborted()) break; |
| |
| // Pause Remark. |
| log_info(gc, marking)("%s (%.3fs, %.3fs) %.3fms", |
| cm_title, |
| TimeHelper::counter_to_seconds(mark_start), |
| TimeHelper::counter_to_seconds(mark_end), |
| TimeHelper::counter_to_millis(mark_end - mark_start)); |
| mark_manager.set_phase(G1ConcurrentPhase::REMARK, false); |
| CMCheckpointRootsFinalClosure final_cl(_cm); |
| VM_CGC_Operation op(&final_cl, "Pause Remark"); |
| VMThread::execute(&op); |
| if (cm()->has_aborted()) { |
| break; |
| } else if (!cm()->restart_for_overflow()) { |
| break; // Exit loop if no restart requested. |
| } else { |
| // Loop to restart for overflow. |
| mark_manager.set_phase(G1ConcurrentPhase::CONCURRENT_MARK, false); |
| log_info(gc, marking)("%s Restart for Mark Stack Overflow (iteration #%u)", |
| cm_title, iter); |
| } |
| } |
| } |
| |
| if (!cm()->has_aborted()) { |
| G1ConcPhase p(G1ConcurrentPhase::CREATE_LIVE_DATA, this); |
| cm()->create_live_data(); |
| } |
| |
| double end_time = os::elapsedVTime(); |
| // Update the total virtual time before doing this, since it will try |
| // to measure it to get the vtime for this marking. We purposely |
| // neglect the presumably-short "completeCleanup" phase here. |
| _vtime_accum = (end_time - _vtime_start); |
| |
| if (!cm()->has_aborted()) { |
| delay_to_keep_mmu(g1_policy, false /* cleanup */); |
| |
| CMCleanUp cl_cl(_cm); |
| VM_CGC_Operation op(&cl_cl, "Pause Cleanup"); |
| VMThread::execute(&op); |
| } else { |
| // We don't want to update the marking status if a GC pause |
| // is already underway. |
| SuspendibleThreadSetJoiner sts_join; |
| g1h->collector_state()->set_mark_in_progress(false); |
| } |
| |
| // Check if cleanup set the free_regions_coming flag. If it |
| // hasn't, we can just skip the next step. |
| if (g1h->free_regions_coming()) { |
| // The following will finish freeing up any regions that we |
| // found to be empty during cleanup. We'll do this part |
| // without joining the suspendible set. If an evacuation pause |
| // takes place, then we would carry on freeing regions in |
| // case they are needed by the pause. If a Full GC takes |
| // place, it would wait for us to process the regions |
| // reclaimed by cleanup. |
| |
| // Now do the concurrent cleanup operation. |
| G1ConcPhase p(G1ConcurrentPhase::COMPLETE_CLEANUP, this); |
| _cm->complete_cleanup(); |
| |
| // Notify anyone who's waiting that there are no more free |
| // regions coming. We have to do this before we join the STS |
| // (in fact, we should not attempt to join the STS in the |
| // interval between finishing the cleanup pause and clearing |
| // the free_regions_coming flag) otherwise we might deadlock: |
| // a GC worker could be blocked waiting for the notification |
| // whereas this thread will be blocked for the pause to finish |
| // while it's trying to join the STS, which is conditional on |
| // the GC workers finishing. |
| g1h->reset_free_regions_coming(); |
| } |
| guarantee(cm()->cleanup_list_is_empty(), |
| "at this point there should be no regions on the cleanup list"); |
| |
| // There is a tricky race before recording that the concurrent |
| // cleanup has completed and a potential Full GC starting around |
| // the same time. We want to make sure that the Full GC calls |
| // abort() on concurrent mark after |
| // record_concurrent_mark_cleanup_completed(), since abort() is |
| // the method that will reset the concurrent mark state. If we |
| // end up calling record_concurrent_mark_cleanup_completed() |
| // after abort() then we might incorrectly undo some of the work |
| // abort() did. Checking the has_aborted() flag after joining |
| // the STS allows the correct ordering of the two methods. There |
| // are two scenarios: |
| // |
| // a) If we reach here before the Full GC, the fact that we have |
| // joined the STS means that the Full GC cannot start until we |
| // leave the STS, so record_concurrent_mark_cleanup_completed() |
| // will complete before abort() is called. |
| // |
| // b) If we reach here during the Full GC, we'll be held up from |
| // joining the STS until the Full GC is done, which means that |
| // abort() will have completed and has_aborted() will return |
| // true to prevent us from calling |
| // record_concurrent_mark_cleanup_completed() (and, in fact, it's |
| // not needed any more as the concurrent mark state has been |
| // already reset). |
| { |
| SuspendibleThreadSetJoiner sts_join; |
| if (!cm()->has_aborted()) { |
| g1_policy->record_concurrent_mark_cleanup_completed(); |
| } else { |
| log_info(gc, marking)("Concurrent Mark Abort"); |
| } |
| } |
| |
| // We now want to allow clearing of the marking bitmap to be |
| // suspended by a collection pause. |
| // We may have aborted just before the remark. Do not bother clearing the |
| // bitmap then, as it has been done during mark abort. |
| if (!cm()->has_aborted()) { |
| G1ConcPhase p(G1ConcurrentPhase::CLEANUP_FOR_NEXT_MARK, this); |
| _cm->cleanup_for_next_mark(); |
| } else { |
| assert(!G1VerifyBitmaps || _cm->nextMarkBitmapIsClear(), "Next mark bitmap must be clear"); |
| } |
| } |
| |
| // Update the number of full collections that have been |
| // completed. This will also notify the FullGCCount_lock in case a |
| // Java thread is waiting for a full GC to happen (e.g., it |
| // called System.gc() with +ExplicitGCInvokesConcurrent). |
| { |
| SuspendibleThreadSetJoiner sts_join; |
| g1h->increment_old_marking_cycles_completed(true /* concurrent */); |
| |
| cm()->concurrent_cycle_end(); |
| } |
| |
| cpmanager.set_phase(G1ConcurrentPhase::IDLE, cm()->has_aborted() /* force */); |
| } |
| _cm->root_regions()->cancel_scan(); |
| } |
| |
| void ConcurrentMarkThread::stop_service() { |
| MutexLockerEx ml(CGC_lock, Mutex::_no_safepoint_check_flag); |
| CGC_lock->notify_all(); |
| } |
| |
| void ConcurrentMarkThread::sleepBeforeNextCycle() { |
| // We join here because we don't want to do the "shouldConcurrentMark()" |
| // below while the world is otherwise stopped. |
| assert(!in_progress(), "should have been cleared"); |
| |
| MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); |
| while (!started() && !should_terminate()) { |
| CGC_lock->wait(Mutex::_no_safepoint_check_flag); |
| } |
| |
| if (started()) { |
| set_in_progress(); |
| } |
| } |