--- a/src/hotspot/share/gc/g1/concurrentMarkThread.cpp Thu Apr 12 16:25:29 2018 -0700
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,486 +0,0 @@
-/*
- * Copyright (c) 2001, 2018, 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/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 "gc/shared/suspendibleThreadSet.hpp"
-#include "logging/log.hpp"
-#include "memory/resourceArea.hpp"
-#include "runtime/handles.inline.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->checkpoint_roots_final(false); // !clear_all_soft_refs
- }
-};
-
-class CMCleanUp: public VoidClosure {
- G1ConcurrentMark* _cm;
-public:
-
- CMCleanUp(G1ConcurrentMark* cm) :
- _cm(cm) {}
-
- void do_void(){
- _cm->cleanup();
- }
-};
-
-double ConcurrentMarkThread::mmu_sleep_time(G1Policy* g1_policy, bool remark) {
- // There are 3 reasons to use SuspendibleThreadSetJoiner.
- // 1. To avoid concurrency problem.
- // - G1MMUTracker::add_pause(), when_sec() and its variation(when_ms() etc..) can be called
- // concurrently from ConcurrentMarkThread and VMThread.
- // 2. If currently a gc is running, but it has not yet updated the MMU,
- // we will not forget to consider that pause in the MMU calculation.
- // 3. If currently a gc is running, ConcurrentMarkThread will wait it to be finished.
- // And then sleep for predicted amount of time by delay_to_keep_mmu().
- SuspendibleThreadSetJoiner sts_join;
-
- const G1Analytics* analytics = g1_policy->analytics();
- 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();
- return mmu_tracker->when_ms(now, prediction_ms);
-}
-
-void ConcurrentMarkThread::delay_to_keep_mmu(G1Policy* g1_policy, bool remark) {
- if (g1_policy->adaptive_young_list_length()) {
- jlong sleep_time_ms = mmu_sleep_time(g1_policy, remark);
- if (!cm()->has_aborted() && sleep_time_ms > 0) {
- 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();
-
- 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 */);
-
- if (!cm()->has_aborted()) {
- 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->next_mark_bitmap_is_clear(), "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();
- }
-}