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src/hotspot/share/gc/g1/g1ConcurrentMarkThread.cpp
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rev 60794 : imported patch 8247928-sjohanss-review
@@ -40,18 +40,16 @@
#include "logging/log.hpp"
#include "memory/resourceArea.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/vmThread.hpp"
#include "utilities/debug.hpp"
-
-// ======= Concurrent Mark Thread ========
+#include "utilities/ticks.hpp"
G1ConcurrentMarkThread::G1ConcurrentMarkThread(G1ConcurrentMark* cm) :
ConcurrentGCThread(),
_vtime_start(0.0),
_vtime_accum(0.0),
- _vtime_mark_accum(0.0),
_cm(cm),
_state(Idle)
{
set_name("G1 Main Marker");
create_and_start();
@@ -75,44 +73,44 @@
void do_void(){
_cm->cleanup();
}
};
-double G1ConcurrentMarkThread::mmu_delay_end(G1Policy* g1_policy, bool remark) {
+double G1ConcurrentMarkThread::mmu_delay_end(G1Policy* 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();
+ const G1Analytics* analytics = policy->analytics();
double prediction_ms = remark ? analytics->predict_remark_time_ms()
: analytics->predict_cleanup_time_ms();
double prediction = prediction_ms / MILLIUNITS;
- G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
+ G1MMUTracker *mmu_tracker = policy->mmu_tracker();
double now = os::elapsedTime();
return now + mmu_tracker->when_sec(now, prediction);
}
-void G1ConcurrentMarkThread::delay_to_keep_mmu(G1Policy* g1_policy, bool remark) {
- if (g1_policy->use_adaptive_young_list_length()) {
- double delay_end_sec = mmu_delay_end(g1_policy, remark);
+void G1ConcurrentMarkThread::delay_to_keep_mmu(bool remark) {
+ G1Policy* policy = G1CollectedHeap::heap()->policy();
+
+ if (policy->use_adaptive_young_list_length()) {
+ double delay_end_sec = mmu_delay_end(policy, remark);
// Wait for timeout or thread termination request.
MonitorLocker ml(CGC_lock, Monitor::_no_safepoint_check_flag);
- while (!_cm->has_aborted()) {
+ while (!_cm->has_aborted() && !should_terminate()) {
double sleep_time_sec = (delay_end_sec - os::elapsedTime());
jlong sleep_time_ms = ceil(sleep_time_sec * MILLIUNITS);
if (sleep_time_ms <= 0) {
break; // Passed end time.
} else if (ml.wait(sleep_time_ms, Monitor::_no_safepoint_check_flag)) {
break; // Timeout => reached end time.
- } else if (should_terminate()) {
- break; // Wakeup for pending termination request.
}
// Other (possibly spurious) wakeup. Retry with updated sleep time.
}
}
}
@@ -134,167 +132,188 @@
};
void G1ConcurrentMarkThread::run_service() {
_vtime_start = os::elapsedVTime();
- G1CollectedHeap* g1h = G1CollectedHeap::heap();
- G1Policy* policy = g1h->policy();
-
while (!should_terminate()) {
- // wait until started is set.
- sleep_before_next_cycle();
- if (should_terminate()) {
+ if (wait_for_next_cycle()) {
break;
}
GCIdMark gc_id_mark;
+ GCTraceConcTime(Info, gc) tt("Concurrent Cycle");
- _cm->concurrent_cycle_start();
+ concurrent_cycle_start();
+ full_concurrent_cycle_do();
+ concurrent_cycle_end();
- GCTraceConcTime(Info, gc) tt("Concurrent Cycle");
- {
- ResourceMark rm;
+ _vtime_accum = (os::elapsedVTime() - _vtime_start);
+ }
+ _cm->root_regions()->cancel_scan();
+}
+
+void G1ConcurrentMarkThread::stop_service() {
+ MutexLocker ml(CGC_lock, Mutex::_no_safepoint_check_flag);
+ CGC_lock->notify_all();
+}
- double cycle_start = os::elapsedVTime();
+bool G1ConcurrentMarkThread::wait_for_next_cycle() {
+ assert(!in_progress(), "should have been cleared");
- {
- G1ConcPhaseTimer p(_cm, "Concurrent Clear Claimed Marks");
- ClassLoaderDataGraph::clear_claimed_marks();
+ MonitorLocker ml(CGC_lock, Mutex::_no_safepoint_check_flag);
+ while (!started() && !should_terminate()) {
+ ml.wait();
}
- // 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.
+ if (started()) {
+ set_in_progress();
+ }
- {
+ return should_terminate();
+}
+
+bool G1ConcurrentMarkThread::phase_clear_cld_claimed_marks() {
+ G1ConcPhaseTimer p(_cm, "Concurrent Clear Claimed Marks");
+ ClassLoaderDataGraph::clear_claimed_marks();
+ return _cm->has_aborted();
+}
+
+bool G1ConcurrentMarkThread::phase_scan_root_regions() {
G1ConcPhaseTimer p(_cm, "Concurrent Scan Root Regions");
_cm->scan_root_regions();
+ return _cm->has_aborted();
+}
+
+bool G1ConcurrentMarkThread::phase_mark_loop() {
+ Ticks mark_start = Ticks::now();
+ log_info(gc, marking)("Concurrent Mark (%.3fs)", mark_start.seconds());
+
+ uint iter = 1;
+ while (true) {
+ // Subphase 1: Mark From Roots.
+ if (subphase_mark_from_roots()) return true;
+
+ // Subphase 2: Preclean (optional)
+ if (G1UseReferencePrecleaning) {
+ if (subphase_preclean()) return true;
}
- // Note: ConcurrentGCBreakpoints before here risk deadlock,
- // because a young GC must wait for root region scanning.
+ // Subphase 3: Wait for Remark.
+ if (subphase_delay_to_keep_mmu_before_remark()) return true;
- // It would be nice to use the G1ConcPhaseTimer 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.
- jlong mark_start = os::elapsed_counter();
- log_info(gc, marking)("Concurrent Mark (%.3fs)",
- TimeHelper::counter_to_seconds(mark_start));
- for (uint iter = 1; !_cm->has_aborted(); ++iter) {
- // Concurrent marking.
- {
+ // Subphase 4: Remark pause
+ if (subphase_remark()) return true;
+
+ // Check if we need to restart the marking loop.
+ if (!mark_loop_needs_restart()) break;
+
+ log_info(gc, marking)("Concurrent Mark Restart for Mark Stack Overflow (iteration #%u)",
+ iter++);
+ }
+
+ Ticks mark_end = Ticks::now();
+ log_info(gc, marking)("Concurrent Mark (%.3fs, %.3fs) %.3fms",
+ mark_start.seconds(), mark_end.seconds(),
+ (mark_end - mark_start).seconds() * 1000.0);
+
+ return false;
+}
+
+bool G1ConcurrentMarkThread::mark_loop_needs_restart() const {
+ return _cm->has_overflown();
+}
+
+bool G1ConcurrentMarkThread::subphase_mark_from_roots() {
ConcurrentGCBreakpoints::at("AFTER MARKING STARTED");
G1ConcPhaseTimer p(_cm, "Concurrent Mark From Roots");
_cm->mark_from_roots();
- }
- if (_cm->has_aborted()) {
- break;
- }
+ return _cm->has_aborted();
+}
- if (G1UseReferencePrecleaning) {
+bool G1ConcurrentMarkThread::subphase_preclean() {
G1ConcPhaseTimer p(_cm, "Concurrent Preclean");
_cm->preclean();
- }
- if (_cm->has_aborted()) {
- break;
- }
+ return _cm->has_aborted();
+}
- // 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(policy, true /* remark */);
- if (_cm->has_aborted()) {
- break;
- }
+bool G1ConcurrentMarkThread::subphase_delay_to_keep_mmu_before_remark() {
+ delay_to_keep_mmu(true /* remark */);
+ return _cm->has_aborted();
+}
- // Pause Remark.
+bool G1ConcurrentMarkThread::subphase_remark() {
ConcurrentGCBreakpoints::at("BEFORE MARKING COMPLETED");
- log_info(gc, marking)("Concurrent Mark (%.3fs, %.3fs) %.3fms",
- TimeHelper::counter_to_seconds(mark_start),
- TimeHelper::counter_to_seconds(mark_end),
- TimeHelper::counter_to_millis(mark_end - mark_start));
CMRemark cl(_cm);
VM_G1Concurrent op(&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.
- log_info(gc, marking)("Concurrent Mark Restart for Mark Stack Overflow (iteration #%u)",
- iter);
- }
- }
+ return _cm->has_aborted();
+}
- if (!_cm->has_aborted()) {
+bool G1ConcurrentMarkThread::phase_rebuild_remembered_sets() {
G1ConcPhaseTimer p(_cm, "Concurrent Rebuild Remembered Sets");
_cm->rebuild_rem_set_concurrently();
- }
+ return _cm->has_aborted();
+}
- 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.
- _vtime_accum = (end_time - _vtime_start);
-
- if (!_cm->has_aborted()) {
- delay_to_keep_mmu(policy, false /* cleanup */);
- }
+bool G1ConcurrentMarkThread::phase_delay_to_keep_mmu_before_cleanup() {
+ delay_to_keep_mmu(false /* cleanup */);
+ return _cm->has_aborted();
+}
- if (!_cm->has_aborted()) {
- CMCleanup cl_cl(_cm);
- VM_G1Concurrent op(&cl_cl, "Pause Cleanup");
+bool G1ConcurrentMarkThread::phase_cleanup() {
+ CMCleanup cl(_cm);
+ VM_G1Concurrent op(&cl, "Pause Cleanup");
VMThread::execute(&op);
- }
+ return _cm->has_aborted();
+}
- // 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()) {
+bool G1ConcurrentMarkThread::phase_clear_bitmap_for_next_mark() {
G1ConcPhaseTimer p(_cm, "Concurrent Cleanup for Next Mark");
_cm->cleanup_for_next_mark();
- }
- }
+ return _cm->has_aborted();
+}
+
+void G1ConcurrentMarkThread::concurrent_cycle_start() {
+ _cm->concurrent_cycle_start();
+}
+
+void G1ConcurrentMarkThread::full_concurrent_cycle_do() {
+ HandleMark hm(Thread::current());
+ ResourceMark rm;
+
+ // Phase 1: Clear CLD claimed marks.
+ phase_clear_cld_claimed_marks();
+
+ // Do not return before the scan root regions phase as a GC waits for a
+ // notification from it.
+
+ // Phase 2: Scan root regions.
+ if (phase_scan_root_regions()) return;
+ // Phase 3: Actual mark loop.
+ if (phase_mark_loop()) return;
+
+ // Phase 4: Rebuild remembered sets.
+ if (phase_rebuild_remembered_sets()) return;
+
+ // Phase 5: Wait for Cleanup.
+ if (phase_delay_to_keep_mmu_before_cleanup()) return;
+
+ // Phase 6: Cleanup pause
+ if (phase_cleanup()) return;
+
+ // Phase 7: Clear bitmap for next mark.
+ phase_clear_bitmap_for_next_mark();
+}
+
+void G1ConcurrentMarkThread::concurrent_cycle_end() {
// Update the number of full collections that have been
// completed. This will also notify the G1OldGCCount_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->has_aborted() /* liveness_completed */);
+ G1CollectedHeap::heap()->increment_old_marking_cycles_completed(true /* concurrent */,
+ !_cm->has_aborted());
_cm->concurrent_cycle_end();
ConcurrentGCBreakpoints::notify_active_to_idle();
- }
- }
- _cm->root_regions()->cancel_scan();
-}
-
-void G1ConcurrentMarkThread::stop_service() {
- MutexLocker ml(CGC_lock, Mutex::_no_safepoint_check_flag);
- CGC_lock->notify_all();
-}
-
-
-void G1ConcurrentMarkThread::sleep_before_next_cycle() {
- // 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");
-
- MonitorLocker ml(CGC_lock, Mutex::_no_safepoint_check_flag);
- while (!started() && !should_terminate()) {
- ml.wait();
- }
-
- if (started()) {
- set_in_progress();
- }
}
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