void ConcurrentMarkThread::run() {
initialize_in_thread();
_vtime_start = os::elapsedVTime();
wait_for_universe_init();
G1CollectedHeap* g1h = G1CollectedHeap::heap();
G1CollectorPolicy* g1_policy = g1h->g1_policy();
G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
Thread *current_thread = Thread::current();
while (!_should_terminate) {
// wait until started is set.
sleepBeforeNextCycle();
{
ResourceMark rm;
HandleMark hm;
double cycle_start = os::elapsedVTime();
double mark_start_sec = os::elapsedTime();
char verbose_str[128];
if (PrintGC) {
gclog_or_tty->date_stamp(PrintGCDateStamps);
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print_cr("[GC concurrent-mark-start]");
}
if (!g1_policy->in_young_gc_mode()) {
// this ensures the flag is not set if we bail out of the marking
// cycle; normally the flag is cleared immediately after cleanup
g1h->set_marking_complete();
if (g1_policy->adaptive_young_list_length()) {
double now = os::elapsedTime();
double init_prediction_ms = g1_policy->predict_init_time_ms();
jlong sleep_time_ms = mmu_tracker->when_ms(now, init_prediction_ms);
os::sleep(current_thread, sleep_time_ms, false);
}
// We don't have to skip here if we've been asked to restart, because
// in the worst case we just enqueue a new VM operation to start a
// marking. Note that the init operation resets has_aborted()
CMCheckpointRootsInitialClosure init_cl(_cm);
strcpy(verbose_str, "GC initial-mark");
VM_CGC_Operation op(&init_cl, verbose_str);
VMThread::execute(&op);
}
int iter = 0;
do {
iter++;
if (!cm()->has_aborted()) {
_cm->markFromRoots();
}
double mark_end_time = os::elapsedVTime();
double mark_end_sec = os::elapsedTime();
_vtime_mark_accum += (mark_end_time - cycle_start);
if (!cm()->has_aborted()) {
if (g1_policy->adaptive_young_list_length()) {
double now = os::elapsedTime();
double remark_prediction_ms = g1_policy->predict_remark_time_ms();
jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
os::sleep(current_thread, sleep_time_ms, false);
}
if (PrintGC) {
gclog_or_tty->date_stamp(PrintGCDateStamps);
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf sec]",
mark_end_sec - mark_start_sec);
}
CMCheckpointRootsFinalClosure final_cl(_cm);
sprintf(verbose_str, "GC remark");
VM_CGC_Operation op(&final_cl, verbose_str);
VMThread::execute(&op);
}
if (cm()->restart_for_overflow() &&
G1TraceMarkStackOverflow) {
gclog_or_tty->print_cr("Restarting conc marking because of MS overflow "
"in remark (restart #%d).", iter);
}
if (cm()->restart_for_overflow()) {
if (PrintGC) {
gclog_or_tty->date_stamp(PrintGCDateStamps);
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]");
}
}
} while (cm()->restart_for_overflow());
double counting_start_time = os::elapsedVTime();
// YSR: These look dubious (i.e. redundant) !!! FIX ME
slt()->manipulatePLL(SurrogateLockerThread::acquirePLL);
slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
if (!cm()->has_aborted()) {
double count_start_sec = os::elapsedTime();
if (PrintGC) {
gclog_or_tty->date_stamp(PrintGCDateStamps);
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print_cr("[GC concurrent-count-start]");
}
_sts.join();
_cm->calcDesiredRegions();
_sts.leave();
if (!cm()->has_aborted()) {
double count_end_sec = os::elapsedTime();
if (PrintGC) {
gclog_or_tty->date_stamp(PrintGCDateStamps);
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print_cr("[GC concurrent-count-end, %1.7lf]",
count_end_sec - count_start_sec);
}
}
}
double end_time = os::elapsedVTime();
_vtime_count_accum += (end_time - counting_start_time);
// 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()) {
if (g1_policy->adaptive_young_list_length()) {
double now = os::elapsedTime();
double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
os::sleep(current_thread, sleep_time_ms, false);
}
CMCleanUp cl_cl(_cm);
sprintf(verbose_str, "GC cleanup");
VM_CGC_Operation op(&cl_cl, verbose_str);
VMThread::execute(&op);
} else {
g1h->set_marking_complete();
}
// 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 places, then we would carry on freeing regions in
// case they are needed by the pause. If a Full GC takes
// places, it would wait for us to process the regions
// reclaimed by cleanup.
double cleanup_start_sec = os::elapsedTime();
if (PrintGC) {
gclog_or_tty->date_stamp(PrintGCDateStamps);
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print_cr("[GC concurrent-cleanup-start]");
}
// Now do the remainder of the cleanup operation.
_cm->completeCleanup();
// Notify anyone who's waiting that there are no more free
// regions coming. We have to do this before we join the STS,
// 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();
_sts.join();
g1_policy->record_concurrent_mark_cleanup_completed();
_sts.leave();
double cleanup_end_sec = os::elapsedTime();
if (PrintGC) {
gclog_or_tty->date_stamp(PrintGCDateStamps);
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf]",
cleanup_end_sec - cleanup_start_sec);
}
}
guarantee(cm()->cleanup_list_is_empty(),
"at this point there should be no regions on the cleanup list");
if (cm()->has_aborted()) {
if (PrintGC) {
gclog_or_tty->date_stamp(PrintGCDateStamps);
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print_cr("[GC concurrent-mark-abort]");
}
}
// we now want to allow clearing of the marking bitmap to be
// suspended by a collection pause.
_sts.join();
_cm->clearNextBitmap();
_sts.leave();
}
// 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).
_sts.join();
g1h->increment_full_collections_completed(true /* concurrent */);
_sts.leave();
}
assert(_should_terminate, "just checking");
terminate();
}
void ConcurrentMarkThread::run() {
initialize_in_thread();
_vtime_start = os::elapsedVTime();
wait_for_universe_init();
G1CollectedHeap* g1h = G1CollectedHeap::heap();
G1CollectorPolicy* g1_policy = g1h->g1_policy();
G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
Thread *current_thread = Thread::current();
while (!_should_terminate) {
// wait until started is set.
sleepBeforeNextCycle();
if (_should_terminate) {
break;
}
{
ResourceMark rm;
HandleMark hm;
double cycle_start = os::elapsedVTime();
// 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 (!cm()->has_aborted()) {
_cm->scanRootRegions();
}
double mark_start_sec = os::elapsedTime();
cm_log(G1Log::fine(), true, "[GC concurrent-mark-start]");
int iter = 0;
do {
iter++;
if (!cm()->has_aborted()) {
_cm->markFromRoots();
}
double mark_end_time = os::elapsedVTime();
double mark_end_sec = os::elapsedTime();
_vtime_mark_accum += (mark_end_time - cycle_start);
if (!cm()->has_aborted()) {
if (g1_policy->adaptive_young_list_length()) {
double now = os::elapsedTime();
double remark_prediction_ms = g1_policy->predict_remark_time_ms();
jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
os::sleep(current_thread, sleep_time_ms, false);
}
cm_log(G1Log::fine(), true, "[GC concurrent-mark-end, %1.7lf secs]", mark_end_sec - mark_start_sec);
CMCheckpointRootsFinalClosure final_cl(_cm);
VM_CGC_Operation op(&final_cl, "GC remark", true /* needs_pll */);
VMThread::execute(&op);
}
if (cm()->restart_for_overflow()) {
cm_log(G1TraceMarkStackOverflow, true, "Restarting conc marking because of MS overflow in remark (restart #%d).", iter);
cm_log(G1Log::fine(), true, "[GC concurrent-mark-restart-for-overflow]");
}
} while (cm()->restart_for_overflow());
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()) {
if (g1_policy->adaptive_young_list_length()) {
double now = os::elapsedTime();
double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
os::sleep(current_thread, sleep_time_ms, false);
}
CMCleanUp cl_cl(_cm);
VM_CGC_Operation op(&cl_cl, "GC cleanup", false /* needs_pll */);
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.
double cleanup_start_sec = os::elapsedTime();
cm_log(G1Log::fine(), true, "[GC concurrent-cleanup-start]");
// Now do the concurrent cleanup operation.
_cm->completeCleanup();
// 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();
double cleanup_end_sec = os::elapsedTime();
cm_log(G1Log::fine(), true, "[GC concurrent-cleanup-end, %1.7lf secs]", cleanup_end_sec - cleanup_start_sec);
}
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 {
cm_log(G1Log::fine(), false, "[GC 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()) {
_cm->clearNextBitmap();
} 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 */);
g1h->register_concurrent_cycle_end();
}
}
assert(_should_terminate, "just checking");
terminate();
}
void ConcurrentMarkThread::run_service() {
_vtime_start = os::elapsedVTime();
G1CollectedHeap* g1h = G1CollectedHeap::heap();
G1CollectorPolicy* g1_policy = g1h->g1_policy();
while (!_should_terminate) {
// wait until started is set.
sleepBeforeNextCycle();
if (_should_terminate) {
break;
}
assert(GCId::current() != GCId::undefined(), "GC id should have been set up by the initial mark GC.");
{
ResourceMark rm;
HandleMark hm;
double cycle_start = os::elapsedVTime();
// 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 (!cm()->has_aborted()) {
GCConcPhaseTimer(_cm, "Concurrent Root Region Scanning");
_cm->scanRootRegions();
}
// It would be nice to use the GCTraceConcTime class here but
// the "end" logging is inside the loop and not at the end of
// a scope. Mimicking the same log output as GCTraceConcTime instead.
jlong mark_start = os::elapsed_counter();
log_info(gc)("Concurrent Mark (%.3fs)", TimeHelper::counter_to_seconds(mark_start));
int iter = 0;
do {
iter++;
if (!cm()->has_aborted()) {
GCConcPhaseTimer(_cm, "Concurrent Mark");
_cm->markFromRoots();
}
double mark_end_time = os::elapsedVTime();
jlong mark_end = os::elapsed_counter();
_vtime_mark_accum += (mark_end_time - cycle_start);
if (!cm()->has_aborted()) {
delay_to_keep_mmu(g1_policy, true /* remark */);
log_info(gc)("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));
CMCheckpointRootsFinalClosure final_cl(_cm);
VM_CGC_Operation op(&final_cl, "Pause Remark", true /* needs_pll */);
VMThread::execute(&op);
}
if (cm()->restart_for_overflow()) {
log_debug(gc)("Restarting conc marking because of MS overflow in remark (restart #%d).", iter);
log_info(gc)("Concurrent Mark restart for overflow");
}
} while (cm()->restart_for_overflow());
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", false /* needs_pll */);
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.
GCTraceConcTime(Info, gc) tt("Concurrent Cleanup");
GCConcPhaseTimer(_cm, "Concurrent Cleanup");
// Now do the concurrent cleanup operation.
_cm->completeCleanup();
// 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)("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()) {
GCConcPhaseTimer(_cm, "Concurrent Bitmap Clearing");
_cm->clearNextBitmap();
} 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 */);
g1h->register_concurrent_cycle_end();
}
}
}
