1 /*
2 * Copyright (c) 2021, 2026, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25
26 #include "classfile/classLoaderDataGraph.inline.hpp"
27 #include "classfile/javaClasses.inline.hpp"
28 #include "code/nmethod.hpp"
29 #include "compiler/oopMap.hpp"
30 #include "gc/g1/g1Allocator.hpp"
31 #include "gc/g1/g1CardSetMemory.hpp"
32 #include "gc/g1/g1CollectedHeap.inline.hpp"
33 #include "gc/g1/g1CollectionSetCandidates.inline.hpp"
34 #include "gc/g1/g1CollectorState.inline.hpp"
35 #include "gc/g1/g1ConcurrentMark.hpp"
36 #include "gc/g1/g1EvacFailureRegions.inline.hpp"
37 #include "gc/g1/g1EvacInfo.hpp"
38 #include "gc/g1/g1GCPhaseTimes.hpp"
39 #include "gc/g1/g1HeapRegion.inline.hpp"
40 #include "gc/g1/g1HeapRegionPrinter.hpp"
41 #include "gc/g1/g1MonitoringSupport.hpp"
42 #include "gc/g1/g1ParScanThreadState.inline.hpp"
43 #include "gc/g1/g1Policy.hpp"
44 #include "gc/g1/g1RegionPinCache.inline.hpp"
45 #include "gc/g1/g1RemSet.hpp"
46 #include "gc/g1/g1RootProcessor.hpp"
47 #include "gc/g1/g1Trace.hpp"
48 #include "gc/g1/g1YoungCollector.hpp"
49 #include "gc/g1/g1YoungGCAllocationFailureInjector.hpp"
50 #include "gc/g1/g1YoungGCPostEvacuateTasks.hpp"
51 #include "gc/g1/g1YoungGCPreEvacuateTasks.hpp"
52 #include "gc/shared/concurrentGCBreakpoints.hpp"
53 #include "gc/shared/gc_globals.hpp"
54 #include "gc/shared/gcTimer.hpp"
55 #include "gc/shared/gcTraceTime.inline.hpp"
56 #include "gc/shared/referenceProcessor.hpp"
57 #include "gc/shared/weakProcessor.inline.hpp"
58 #include "gc/shared/workerPolicy.hpp"
59 #include "gc/shared/workerThread.hpp"
60 #include "jfr/jfrEvents.hpp"
61 #include "memory/resourceArea.hpp"
62 #include "runtime/atomic.hpp"
63 #include "runtime/threads.hpp"
64 #include "utilities/ticks.hpp"
65
66 // GCTraceTime wrapper that constructs the message according to GC pause type and
67 // GC cause.
68 // The code relies on the fact that GCTraceTimeWrapper stores the string passed
69 // initially as a reference only, so that we can modify it as needed.
70 class G1YoungGCTraceTime {
71 G1YoungCollector* _collector;
72
73 GCCause::Cause _pause_cause;
74
75 static const uint MaxYoungGCNameLength = 128;
76 char _young_gc_name_data[MaxYoungGCNameLength];
77
78 GCTraceTime(Info, gc) _tt;
79
80 const char* update_young_gc_name() {
81 char evacuation_failed_string[48];
82 evacuation_failed_string[0] = '\0';
83
84 if (_collector->evacuation_failed()) {
85 os::snprintf_checked(evacuation_failed_string,
86 ARRAY_SIZE(evacuation_failed_string),
87 " (Evacuation Failure: %s%s%s)",
88 _collector->evacuation_alloc_failed() ? "Allocation" : "",
89 _collector->evacuation_alloc_failed() && _collector->evacuation_pinned() ? " / " : "",
90 _collector->evacuation_pinned() ? "Pinned" : "");
91 }
92 G1CollectorState::Pause pause = _collector->collector_state()->gc_pause_type(_collector->concurrent_operation_is_full_mark());
93 os::snprintf_checked(_young_gc_name_data,
94 MaxYoungGCNameLength,
95 "Pause Young (%s) (%s)%s",
96 G1CollectorState::to_string(pause),
97 GCCause::to_string(_pause_cause),
98 evacuation_failed_string);
99 return _young_gc_name_data;
100 }
101
102 public:
103 G1YoungGCTraceTime(G1YoungCollector* collector, GCCause::Cause cause) :
104 _collector(collector),
105 _pause_cause(cause),
106 // Fake a "no cause" and manually add the correct string in update_young_gc_name()
107 // to make the string look more natural.
108 _tt(update_young_gc_name(), nullptr, GCCause::_no_gc, true) {
109 }
110
111 ~G1YoungGCTraceTime() {
112 update_young_gc_name();
113 }
114 };
115
116 class G1YoungGCNotifyPauseMark : public StackObj {
117 G1YoungCollector* _collector;
118
119 public:
120 G1YoungGCNotifyPauseMark(G1YoungCollector* collector) : _collector(collector) {
121 G1CollectedHeap::heap()->policy()->record_young_gc_pause_start();
122 }
123
124 ~G1YoungGCNotifyPauseMark() {
125 G1CollectedHeap::heap()->policy()->record_young_gc_pause_end(_collector->evacuation_failed());
126 }
127 };
128
129 class G1YoungGCJFRTracerMark : public G1JFRTracerMark {
130 G1YoungCollector* _young_collector;
131 G1EvacInfo _evacuation_info;
132
133 G1NewTracer* tracer() const { return (G1NewTracer*)_tracer; }
134
135 public:
136 G1EvacInfo* evacuation_info() { return &_evacuation_info; }
137
138 G1YoungGCJFRTracerMark(G1YoungCollector* young_collector) :
139 G1JFRTracerMark(young_collector->gc_timer_stw(), young_collector->gc_tracer_stw()),
140 _young_collector(young_collector),
141 _evacuation_info() { }
142
143 ~G1YoungGCJFRTracerMark() {
144 G1CollectedHeap* g1h = G1CollectedHeap::heap();
145
146 tracer()->report_young_gc_pause(g1h->collector_state()->gc_pause_type(_young_collector->concurrent_operation_is_full_mark()));
147 tracer()->report_evacuation_info(&_evacuation_info);
148 tracer()->report_tenuring_threshold(g1h->policy()->tenuring_threshold());
149 }
150 };
151
152 class G1YoungGCVerifierMark : public StackObj {
153 G1YoungCollector* _collector;
154 G1HeapVerifier::G1VerifyType _type;
155
156 static G1HeapVerifier::G1VerifyType young_collection_verify_type() {
157 G1CollectorState* state = G1CollectedHeap::heap()->collector_state();
158 if (state->is_in_concurrent_start_gc()) {
159 return G1HeapVerifier::G1VerifyConcurrentStart;
160 } else if (state->is_in_young_only_phase()) {
161 return G1HeapVerifier::G1VerifyYoungNormal;
162 } else {
163 return G1HeapVerifier::G1VerifyMixed;
164 }
165 }
166
167 public:
168 G1YoungGCVerifierMark(G1YoungCollector* collector) : _collector(collector), _type(young_collection_verify_type()) {
169 G1CollectedHeap::heap()->verify_before_young_collection(_type);
170 }
171
172 ~G1YoungGCVerifierMark() {
173 // Inject evacuation failure tag into type if needed.
174 G1HeapVerifier::G1VerifyType type = _type;
175 if (_collector->evacuation_failed()) {
176 type = (G1HeapVerifier::G1VerifyType)(type | G1HeapVerifier::G1VerifyYoungEvacFail);
177 }
178 G1CollectedHeap::heap()->verify_after_young_collection(type);
179 }
180 };
181
182 G1Allocator* G1YoungCollector::allocator() const {
183 return _g1h->allocator();
184 }
185
186 G1CollectionSet* G1YoungCollector::collection_set() const {
187 return _g1h->collection_set();
188 }
189
190 G1CollectorState* G1YoungCollector::collector_state() const {
191 return _g1h->collector_state();
192 }
193
194 G1ConcurrentMark* G1YoungCollector::concurrent_mark() const {
195 return _g1h->concurrent_mark();
196 }
197
198 STWGCTimer* G1YoungCollector::gc_timer_stw() const {
199 return _g1h->gc_timer_stw();
200 }
201
202 G1NewTracer* G1YoungCollector::gc_tracer_stw() const {
203 return _g1h->gc_tracer_stw();
204 }
205
206 G1Policy* G1YoungCollector::policy() const {
207 return _g1h->policy();
208 }
209
210 G1GCPhaseTimes* G1YoungCollector::phase_times() const {
211 return _g1h->phase_times();
212 }
213
214 G1MonitoringSupport* G1YoungCollector::monitoring_support() const {
215 return _g1h->monitoring_support();
216 }
217
218 G1RemSet* G1YoungCollector::rem_set() const {
219 return _g1h->rem_set();
220 }
221
222 G1ScannerTasksQueueSet* G1YoungCollector::task_queues() const {
223 return _g1h->task_queues();
224 }
225
226 G1SurvivorRegions* G1YoungCollector::survivor_regions() const {
227 return _g1h->survivor();
228 }
229
230 ReferenceProcessor* G1YoungCollector::ref_processor_stw() const {
231 return _g1h->ref_processor_stw();
232 }
233
234 WorkerThreads* G1YoungCollector::workers() const {
235 return _g1h->workers();
236 }
237
238 G1YoungGCAllocationFailureInjector* G1YoungCollector::allocation_failure_injector() const {
239 return _g1h->allocation_failure_injector();
240 }
241
242 void G1YoungCollector::complete_root_region_scan() {
243 Ticks start = Ticks::now();
244 if (concurrent_mark()->complete_root_regions_scan_in_safepoint()) {
245 phase_times()->record_root_region_scan_time((Ticks::now() - start).seconds() * MILLIUNITS);
246 }
247 }
248
249 class G1PrintCollectionSetClosure : public G1HeapRegionClosure {
250 public:
251 virtual bool do_heap_region(G1HeapRegion* r) {
252 G1HeapRegionPrinter::cset(r);
253 return false;
254 }
255 };
256
257 void G1YoungCollector::calculate_collection_set(G1EvacInfo* evacuation_info, double target_pause_time_ms) {
258 // Forget the current allocation region (we might even choose it to be part
259 // of the collection set!) before finalizing the collection set.
260 allocator()->release_mutator_alloc_regions();
261
262 collection_set()->finalize_initial_collection_set(target_pause_time_ms, survivor_regions());
263 evacuation_info->set_collection_set_regions(collection_set()->initial_region_length() +
264 collection_set()->num_optional_regions());
265
266 concurrent_mark()->verify_no_collection_set_oops();
267
268 if (G1HeapRegionPrinter::is_active()) {
269 G1PrintCollectionSetClosure cl;
270 collection_set()->iterate(&cl);
271 collection_set()->iterate_optional(&cl);
272 }
273 }
274
275 class G1PrepareEvacuationTask : public WorkerTask {
276 class G1PrepareRegionsClosure : public G1HeapRegionClosure {
277 G1CollectedHeap* _g1h;
278 G1PrepareEvacuationTask* _parent_task;
279 uint _worker_humongous_total;
280 uint _worker_humongous_candidates;
281
282 G1MonotonicArenaMemoryStats _humongous_card_set_stats;
283
284 bool humongous_region_is_candidate(G1HeapRegion* region) const {
285 assert(region->is_starts_humongous(), "Must start a humongous object");
286
287 oop obj = cast_to_oop(region->bottom());
288
289 // Dead objects cannot be eager reclaim candidates. Due to class
290 // unloading it is unsafe to query their classes so we return early.
291 if (_g1h->is_obj_dead(obj, region)) {
292 return false;
293 }
294
295 // If we do not have a complete remembered set for the region, then we can
296 // not be sure that we have all references to it.
297 if (!region->rem_set()->is_complete()) {
298 return false;
299 }
300 // We also cannot collect the humongous object if it is pinned.
301 if (region->has_pinned_objects()) {
302 return false;
303 }
304 // Candidate selection must satisfy the following constraints
305 // while concurrent marking is in progress:
306 //
307 // * In order to maintain SATB invariants, an object must not be
308 // reclaimed if it was allocated before the start of marking and
309 // has not had its references scanned. Such an object must have
310 // its references (including type metadata) scanned to ensure no
311 // live objects are missed by the marking process. Objects
312 // allocated after the start of concurrent marking don't need to
313 // be scanned.
314 //
315 // * An object must not be reclaimed if it is on the concurrent
316 // mark stack. Objects allocated after the start of concurrent
317 // marking are never pushed on the mark stack.
318 //
319 // Nominating only objects allocated after the start of concurrent
320 // marking is sufficient to meet both constraints. This may miss
321 // some objects that satisfy the constraints, but the marking data
322 // structures don't support efficiently performing the needed
323 // additional tests or scrubbing of the mark stack.
324 //
325 // We handle humongous objects specially, because frequent allocation and
326 // dropping of large binary blobs is an important use case for eager reclaim,
327 // and this special handling increases needed headroom.
328 // It also helps with G1 allocating humongous objects as old generation
329 // objects although they might also die quite quickly.
330 //
331 // Humongous objects without oops (typeArrays, flatArrays without oops in
332 // its elements) are allowed to be reclaimed even if allocated before
333 // the start of concurrent mark. For this we rely on mark stack insertion
334 // to exclude them, preventing reclaiming an object
335 // that is in the mark stack. That code also ensures that metadata (klass)
336 // is kept live.
337 //
338 // Other humongous objects that were allocated before marking are excluded from
339 // eager reclaim during marking. One issue is the problem described
340 // above with scrubbing the mark stack, but there is also a problem
341 // causing these humongous objects being collected incorrectly:
342 //
343 // E.g. if the mutator is running, we may have objects o1 and o2 in the same
344 // region, where o1 has already been scanned and o2 is only reachable by
345 // the candidate object h, which is humongous.
346 //
347 // If the mutator read the reference to o2 from h and installed it into o1,
348 // no remembered set entry would be created for keeping alive o2, as o1 and
349 // o2 are in the same region. Object h might be reclaimed by the next
350 // garbage collection. o1 still has the reference to o2, but since o1 had
351 // already been scanned we do not detect o2 to be still live and reclaim it.
352 //
353 // There is another minor problem with these humongous objects with oops being
354 // the source of remembered set entries in other region's remembered sets.
355 // There are two cases: first, the remembered set entry is in a Free region
356 // after reclaim. We handle this case by ignoring these cards during merging
357 // the remembered sets.
358 //
359 // Second, there may be cases where regions previously containing eagerly
360 // reclaimed objects were already allocated into again.
361 // This may cause scanning of these outdated remembered set entries,
362 // containing some objects. But apart from extra work this does not cause
363 // correctness issues.
364 // There is no difference between scanning cards covering an effectively
365 // dead humongous object vs. some other objects in reallocated regions.
366 //
367 // TAMSes are only reset after completing the entire mark cycle, during
368 // bitmap clearing. It is worth to not wait until then, and allow reclamation
369 // outside of actual (concurrent) SATB marking.
370 // This also applies to the concurrent start pause - we only set
371 // mark_in_progress() at the end of that GC: no mutator is running that can
372 // sneakily install a new reference to the potentially reclaimed humongous
373 // object.
374 // During the concurrent start pause the situation described above where we
375 // miss a reference can not happen. No mutator is modifying the object
376 // graph to install such an overlooked reference.
377 //
378 // After the pause, having reclaimed h, obviously the mutator can't fetch
379 // the reference from h any more.
380 bool marked_immediately = _g1h->can_be_marked_through_immediately(obj);
381 if (!marked_immediately) {
382 // All regions that were allocated before marking have a TAMS != bottom.
383 bool allocated_before_mark_start = region->bottom() != _g1h->concurrent_mark()->top_at_mark_start(region);
384 bool mark_in_progress = _g1h->collector_state()->is_in_marking();
385
386 if (allocated_before_mark_start && mark_in_progress) {
387 return false;
388 }
389 }
390 return _g1h->is_potential_eager_reclaim_candidate(region);
391 }
392
393 public:
394 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
395 _g1h(g1h),
396 _parent_task(parent_task),
397 _worker_humongous_total(0),
398 _worker_humongous_candidates(0),
399 _humongous_card_set_stats() { }
400
401 ~G1PrepareRegionsClosure() {
402 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
403 _parent_task->add_humongous_total(_worker_humongous_total);
404 }
405
406 virtual bool do_heap_region(G1HeapRegion* hr) {
407 // First prepare the region for scanning
408 _g1h->rem_set()->prepare_region_for_scan(hr);
409
410 // Now check if region is a humongous candidate
411 if (!hr->is_starts_humongous()) {
412 _g1h->update_region_attr(hr);
413 return false;
414 }
415
416 uint index = hr->hrm_index();
417 if (humongous_region_is_candidate(hr)) {
418 _g1h->register_humongous_candidate_region_with_region_attr(index);
419 _worker_humongous_candidates++;
420 // We will later handle the remembered sets of these regions.
421 } else {
422 _g1h->update_region_attr(hr);
423 }
424
425 // Sample card set sizes for humongous regions before GC: this makes the policy
426 // to give back memory to the OS keep the most recent amount of memory for these regions.
427 _humongous_card_set_stats.add(hr->rem_set()->card_set_memory_stats());
428
429 log_debug(gc, humongous)("Humongous region %u (object size %zu @ " PTR_FORMAT ") remset %zu code roots %zu "
430 "marked %d pinned count %zu reclaim candidate %d type %s",
431 index,
432 cast_to_oop(hr->bottom())->size() * HeapWordSize,
433 p2i(hr->bottom()),
434 hr->rem_set()->occupied(),
435 hr->rem_set()->code_roots_list_length(),
436 _g1h->concurrent_mark()->mark_bitmap()->is_marked(hr->bottom()),
437 hr->pinned_count(),
438 _g1h->is_humongous_reclaim_candidate(index),
439 cast_to_oop(hr->bottom())->is_typeArray() ? "tA"
440 : (cast_to_oop(hr->bottom())->is_objArray() ? "oA" : "ob")
441 );
442 _worker_humongous_total++;
443
444 return false;
445 }
446
447 G1MonotonicArenaMemoryStats humongous_card_set_stats() const {
448 return _humongous_card_set_stats;
449 }
450 };
451
452 G1CollectedHeap* _g1h;
453 G1HeapRegionClaimer _claimer;
454 Atomic<uint> _humongous_total;
455 Atomic<uint> _humongous_candidates;
456
457 G1MonotonicArenaMemoryStats _all_card_set_stats;
458
459 public:
460 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
461 WorkerTask("Prepare Evacuation"),
462 _g1h(g1h),
463 _claimer(_g1h->workers()->active_workers()),
464 _humongous_total(0),
465 _humongous_candidates(0) { }
466
467 void work(uint worker_id) {
468 G1PrepareRegionsClosure cl(_g1h, this);
469 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
470
471 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
472 _all_card_set_stats.add(cl.humongous_card_set_stats());
473 }
474
475 void add_humongous_candidates(uint candidates) {
476 _humongous_candidates.add_then_fetch(candidates);
477 }
478
479 void add_humongous_total(uint total) {
480 _humongous_total.add_then_fetch(total);
481 }
482
483 uint humongous_candidates() {
484 return _humongous_candidates.load_relaxed();
485 }
486
487 uint humongous_total() {
488 return _humongous_total.load_relaxed();
489 }
490
491 const G1MonotonicArenaMemoryStats all_card_set_stats() const {
492 return _all_card_set_stats;
493 }
494 };
495
496 Tickspan G1YoungCollector::run_task_timed(WorkerTask* task) {
497 Ticks start = Ticks::now();
498 workers()->run_task(task);
499 return Ticks::now() - start;
500 }
501
502 void G1YoungCollector::set_young_collection_default_active_worker_threads(){
503 uint active_workers = WorkerPolicy::calc_active_workers(workers()->max_workers(),
504 workers()->active_workers(),
505 Threads::number_of_non_daemon_threads());
506 active_workers = workers()->set_active_workers(active_workers);
507 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->max_workers());
508 }
509
510 void G1YoungCollector::pre_evacuate_collection_set(G1EvacInfo* evacuation_info) {
511 // Flush various data in thread-local buffers to be able to determine the collection
512 // set
513 {
514 Ticks start = Ticks::now();
515 G1PreEvacuateCollectionSetBatchTask cl;
516 G1CollectedHeap::heap()->run_batch_task(&cl);
517 phase_times()->record_pre_evacuate_prepare_time_ms((Ticks::now() - start).seconds() * 1000.0);
518 }
519
520 // Needs log buffers flushed.
521 calculate_collection_set(evacuation_info, policy()->max_pause_time_ms());
522
523 if (collector_state()->is_in_concurrent_start_gc()) {
524 Ticks start = Ticks::now();
525 concurrent_mark()->pre_concurrent_start(_gc_cause);
526 phase_times()->record_prepare_concurrent_task_time_ms((Ticks::now() - start).seconds() * 1000.0);
527 }
528
529 // Please see comment in g1CollectedHeap.hpp and
530 // G1CollectedHeap::ref_processing_init() to see how
531 // reference processing currently works in G1.
532 ref_processor_stw()->start_discovery(false /* always_clear */);
533
534 _evac_failure_regions.pre_collection(_g1h->max_num_regions());
535
536 _g1h->gc_prologue(false);
537
538 // Initialize the GC alloc regions.
539 allocator()->init_gc_alloc_regions(evacuation_info);
540
541 {
542 Ticks start = Ticks::now();
543 rem_set()->prepare_for_scan_heap_roots();
544
545 _g1h->collection_set()->prepare_for_scan();
546
547 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
548 }
549
550 {
551 G1PrepareEvacuationTask g1_prep_task(_g1h);
552 Tickspan task_time = run_task_timed(&g1_prep_task);
553
554 G1MonotonicArenaMemoryStats sampled_card_set_stats = g1_prep_task.all_card_set_stats();
555 sampled_card_set_stats.add(_g1h->young_regions_cset_group()->card_set_memory_stats());
556 _g1h->set_young_gen_card_set_stats(sampled_card_set_stats);
557 _g1h->set_humongous_stats(g1_prep_task.humongous_total(), g1_prep_task.humongous_candidates());
558
559 phase_times()->record_register_regions(task_time.seconds() * 1000.0);
560 }
561
562 assert(_g1h->verifier()->check_region_attr_table(), "Inconsistency in the region attributes table.");
563
564 #if COMPILER2_OR_JVMCI
565 DerivedPointerTable::clear();
566 #endif
567
568 allocation_failure_injector()->arm_if_needed();
569 }
570
571 class G1ParEvacuateFollowersClosure : public VoidClosure {
572 double _start_term;
573 double _term_time;
574 size_t _term_attempts;
575
576 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
577 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
578
579 G1CollectedHeap* _g1h;
580 G1ParScanThreadState* _par_scan_state;
581 G1ScannerTasksQueueSet* _queues;
582 TaskTerminator* _terminator;
583 G1GCPhaseTimes::GCParPhases _phase;
584
585 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
586 G1ScannerTasksQueueSet* queues() { return _queues; }
587 TaskTerminator* terminator() { return _terminator; }
588
589 inline bool offer_termination() {
590 EventGCPhaseParallel event;
591 G1ParScanThreadState* const pss = par_scan_state();
592 start_term_time();
593 const bool res = (terminator() == nullptr) ? true : terminator()->offer_termination();
594 end_term_time();
595 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
596 return res;
597 }
598
599 public:
600 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
601 G1ParScanThreadState* par_scan_state,
602 G1ScannerTasksQueueSet* queues,
603 TaskTerminator* terminator,
604 G1GCPhaseTimes::GCParPhases phase)
605 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
606 _g1h(g1h), _par_scan_state(par_scan_state),
607 _queues(queues), _terminator(terminator), _phase(phase) {}
608
609 void do_void() {
610 EventGCPhaseParallel event;
611 G1ParScanThreadState* const pss = par_scan_state();
612 pss->trim_queue();
613 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
614 do {
615 EventGCPhaseParallel event;
616 pss->steal_and_trim_queue(queues());
617 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
618 } while (!offer_termination());
619 }
620
621 double term_time() const { return _term_time; }
622 size_t term_attempts() const { return _term_attempts; }
623 };
624
625 class G1EvacuateRegionsBaseTask : public WorkerTask {
626
627 // All pinned regions in the collection set must be registered as failed
628 // regions as there is no guarantee that there is a reference reachable by
629 // Java code (i.e. only by native code) that adds it to the evacuation failed
630 // regions.
631 void record_pinned_regions(G1ParScanThreadState* pss, uint worker_id) {
632 class RecordPinnedRegionClosure : public G1HeapRegionClosure {
633 G1ParScanThreadState* _pss;
634 uint _worker_id;
635
636 public:
637 RecordPinnedRegionClosure(G1ParScanThreadState* pss, uint worker_id) : _pss(pss), _worker_id(worker_id) { }
638
639 bool do_heap_region(G1HeapRegion* r) {
640 if (r->has_pinned_objects()) {
641 _pss->record_evacuation_failed_region(r, _worker_id, true /* cause_pinned */);
642 }
643 return false;
644 }
645 } cl(pss, worker_id);
646
647 _g1h->collection_set_iterate_increment_from(&cl, worker_id);
648 }
649
650 protected:
651 G1CollectedHeap* _g1h;
652 G1ParScanThreadStateSet* _per_thread_states;
653
654 G1ScannerTasksQueueSet* _task_queues;
655 TaskTerminator _terminator;
656
657 void evacuate_live_objects(G1ParScanThreadState* pss,
658 uint worker_id,
659 G1GCPhaseTimes::GCParPhases objcopy_phase,
660 G1GCPhaseTimes::GCParPhases termination_phase) {
661 G1GCPhaseTimes* p = _g1h->phase_times();
662
663 Ticks start = Ticks::now();
664 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
665 cl.do_void();
666
667 assert(pss->queue_is_empty(), "should be empty");
668
669 Tickspan evac_time = (Ticks::now() - start);
670 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
671
672 if (termination_phase == G1GCPhaseTimes::Termination) {
673 p->record_time_secs(termination_phase, worker_id, cl.term_time());
674 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
675 } else {
676 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
677 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
678 }
679 assert(pss->trim_ticks().value() == 0,
680 "Unexpected partial trimming during evacuation value " JLONG_FORMAT,
681 pss->trim_ticks().value());
682 }
683
684 virtual void start_work(uint worker_id) { }
685
686 virtual void end_work(uint worker_id) { }
687
688 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
689
690 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
691
692 private:
693 Atomic<bool> _pinned_regions_recorded;
694
695 public:
696 G1EvacuateRegionsBaseTask(const char* name,
697 G1ParScanThreadStateSet* per_thread_states,
698 G1ScannerTasksQueueSet* task_queues,
699 uint num_workers) :
700 WorkerTask(name),
701 _g1h(G1CollectedHeap::heap()),
702 _per_thread_states(per_thread_states),
703 _task_queues(task_queues),
704 _terminator(num_workers, _task_queues),
705 _pinned_regions_recorded(false)
706 { }
707
708 void work(uint worker_id) {
709 start_work(worker_id);
710
711 {
712 ResourceMark rm;
713
714 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
715 pss->set_ref_discoverer(_g1h->ref_processor_stw());
716
717 if (_pinned_regions_recorded.compare_set(false, true)) {
718 record_pinned_regions(pss, worker_id);
719 }
720 scan_roots(pss, worker_id);
721 evacuate_live_objects(pss, worker_id);
722 }
723
724 end_work(worker_id);
725 }
726 };
727
728 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
729 G1RootProcessor* _root_processor;
730 bool _has_optional_evacuation_work;
731
732 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
733 _root_processor->evacuate_roots(pss, worker_id);
734 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy, _has_optional_evacuation_work);
735 _g1h->rem_set()->scan_collection_set_code_roots(pss, worker_id, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
736 // There are no optional roots to scan right now.
737 #ifdef ASSERT
738 class VerifyOptionalCollectionSetRootsEmptyClosure : public G1HeapRegionClosure {
739 G1ParScanThreadState* _pss;
740
741 public:
742 VerifyOptionalCollectionSetRootsEmptyClosure(G1ParScanThreadState* pss) : _pss(pss) { }
743
744 bool do_heap_region(G1HeapRegion* r) override {
745 assert(!r->has_index_in_opt_cset(), "must be");
746 return false;
747 }
748 } cl(pss);
749 _g1h->collection_set_iterate_increment_from(&cl, worker_id);
750 #endif
751 }
752
753 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
754 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
755 }
756
757 void start_work(uint worker_id) {
758 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
759 }
760
761 void end_work(uint worker_id) {
762 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
763 }
764
765 public:
766 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
767 G1ParScanThreadStateSet* per_thread_states,
768 G1ScannerTasksQueueSet* task_queues,
769 G1RootProcessor* root_processor,
770 uint num_workers,
771 bool has_optional_evacuation_work) :
772 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
773 _root_processor(root_processor),
774 _has_optional_evacuation_work(has_optional_evacuation_work)
775 { }
776 };
777
778 void G1YoungCollector::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states,
779 bool has_optional_evacuation_work) {
780 G1GCPhaseTimes* p = phase_times();
781
782 rem_set()->merge_heap_roots(true /* initial_evacuation */);
783
784 Tickspan task_time;
785 const uint num_workers = workers()->active_workers();
786
787 Ticks start_processing = Ticks::now();
788 {
789 G1RootProcessor root_processor(_g1h, num_workers > 1 /* is_parallel */);
790 G1EvacuateRegionsTask g1_par_task(_g1h,
791 per_thread_states,
792 task_queues(),
793 &root_processor,
794 num_workers,
795 has_optional_evacuation_work);
796 task_time = run_task_timed(&g1_par_task);
797 // Closing the inner scope will execute the destructor for the
798 // G1RootProcessor object. By subtracting the WorkerThreads task from the total
799 // time of this scope, we get the "NMethod List Cleanup" time. This list is
800 // constructed during "STW two-phase nmethod root processing", see more in
801 // nmethod.hpp
802 }
803 Tickspan total_processing = Ticks::now() - start_processing;
804
805 p->record_initial_evac_time(task_time.seconds() * 1000.0);
806 p->record_or_add_nmethod_list_cleanup_time((total_processing - task_time).seconds() * 1000.0);
807
808 rem_set()->complete_evac_phase(has_optional_evacuation_work);
809 }
810
811 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
812
813 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
814 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy, true /* remember_already_scanned_cards */);
815 _g1h->rem_set()->scan_collection_set_code_roots(pss, worker_id, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
816 _g1h->rem_set()->scan_collection_set_optional_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::ObjCopy);
817 }
818
819 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
820 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
821 }
822
823 public:
824 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
825 G1ScannerTasksQueueSet* queues,
826 uint num_workers) :
827 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
828 }
829 };
830
831 void G1YoungCollector::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
832 Tickspan task_time;
833
834 Ticks start_processing = Ticks::now();
835 {
836 NMethodMarkingScope nmethod_marking_scope;
837 G1EvacuateOptionalRegionsTask task(per_thread_states, task_queues(), workers()->active_workers());
838 task_time = run_task_timed(&task);
839 // See comment in evacuate_initial_collection_set() for the reason of the scope.
840 }
841 Tickspan total_processing = Ticks::now() - start_processing;
842
843 G1GCPhaseTimes* p = phase_times();
844 p->record_or_add_optional_evac_time(task_time.seconds() * 1000.0);
845 p->record_or_add_nmethod_list_cleanup_time((total_processing - task_time).seconds() * 1000.0);
846 }
847
848 void G1YoungCollector::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
849 const double pause_start_time_ms = policy()->cur_pause_start_sec() * 1000.0;
850 double target_pause_time_ms = MaxGCPauseMillis;
851
852 if (G1ForceOptionalEvacuation) {
853 target_pause_time_ms = DBL_MAX;
854 }
855
856 while (!evacuation_alloc_failed() && collection_set()->num_optional_regions() > 0) {
857
858 double time_used_ms = os::elapsedTime() * 1000.0 - pause_start_time_ms;
859 double time_left_ms = target_pause_time_ms - time_used_ms;
860
861 if (time_left_ms <= 0 ||
862 !collection_set()->finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
863 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
864 collection_set()->num_optional_regions(), time_left_ms);
865 break;
866 }
867
868 rem_set()->merge_heap_roots(false /* initial_evacuation */);
869
870 evacuate_next_optional_regions(per_thread_states);
871
872 rem_set()->complete_evac_phase(true /* has_more_than_one_evacuation_phase */);
873 }
874
875 collection_set()->abandon_optional_collection_set(per_thread_states);
876 }
877
878 // Non Copying Keep Alive closure
879 class G1KeepAliveClosure: public OopClosure {
880 G1CollectedHeap*_g1h;
881 public:
882 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
883 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
884 void do_oop(oop* p) {
885 oop obj = *p;
886 assert(obj != nullptr, "the caller should have filtered out null values");
887
888 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
889 assert(!region_attr.is_humongous_candidate(), "Humongous candidates should never be considered alive");
890 if (region_attr.is_in_cset()) {
891 assert(obj->is_forwarded(), "invariant" );
892 *p = obj->forwardee();
893 }
894 }
895 };
896
897 // Copying Keep Alive closure - can be called from both
898 // serial and parallel code as long as different worker
899 // threads utilize different G1ParScanThreadState instances
900 // and different queues.
901 class G1CopyingKeepAliveClosure: public OopClosure {
902 G1CollectedHeap* _g1h;
903 G1ParScanThreadState* _par_scan_state;
904
905 public:
906 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
907 G1ParScanThreadState* pss):
908 _g1h(g1h),
909 _par_scan_state(pss)
910 {}
911
912 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
913 virtual void do_oop( oop* p) { do_oop_work(p); }
914
915 template <class T> void do_oop_work(T* p) {
916 oop obj = RawAccess<>::oop_load(p);
917
918 assert(!_g1h->region_attr(obj).is_humongous_candidate(), "Humongous candidates should never be considered alive");
919 if (_g1h->is_in_cset(obj)) {
920 // If the referent object has been forwarded (either copied
921 // to a new location or to itself in the event of an
922 // evacuation failure) then we need to update the reference
923 // field and, if both reference and referent are in the G1
924 // heap, update the RSet for the referent.
925 //
926 // If the referent has not been forwarded then we have to keep
927 // it alive by policy. Therefore we have copy the referent.
928 //
929 // When the queue is drained (after each phase of reference processing)
930 // the object and it's followers will be copied, the reference field set
931 // to point to the new location, and the RSet updated.
932 _par_scan_state->push_on_queue(ScannerTask(p));
933 }
934 }
935 };
936
937 class G1STWRefProcProxyTask : public RefProcProxyTask {
938 G1CollectedHeap& _g1h;
939 G1ParScanThreadStateSet& _pss;
940 TaskTerminator _terminator;
941 G1ScannerTasksQueueSet& _task_queues;
942
943 // G1 specific closure for marking discovered fields. Need to mark the card in the
944 // refinement table as the card table is in use by garbage collection.
945 class G1EnqueueDiscoveredFieldClosure : public EnqueueDiscoveredFieldClosure {
946 G1CollectedHeap* _g1h;
947 G1ParScanThreadState* _pss;
948
949 public:
950 G1EnqueueDiscoveredFieldClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : _g1h(g1h), _pss(pss) { }
951
952 void enqueue(HeapWord* discovered_field_addr, oop value) override {
953 assert(_g1h->is_in(discovered_field_addr), PTR_FORMAT " is not in heap ", p2i(discovered_field_addr));
954 // Store the value first, whatever it is.
955 RawAccess<>::oop_store(discovered_field_addr, value);
956 if (value == nullptr) {
957 return;
958 }
959 _pss->write_ref_field_post(discovered_field_addr, value);
960 }
961 };
962
963 public:
964 G1STWRefProcProxyTask(uint max_workers, G1CollectedHeap& g1h, G1ParScanThreadStateSet& pss, G1ScannerTasksQueueSet& task_queues)
965 : RefProcProxyTask("G1STWRefProcProxyTask", max_workers),
966 _g1h(g1h),
967 _pss(pss),
968 _terminator(max_workers, &task_queues),
969 _task_queues(task_queues) {}
970
971 void work(uint worker_id) override {
972 assert(worker_id < _max_workers, "sanity");
973 uint index = (_tm == RefProcThreadModel::Single) ? 0 : worker_id;
974
975 G1ParScanThreadState* pss = _pss.state_for_worker(index);
976 pss->set_ref_discoverer(nullptr);
977
978 G1STWIsAliveClosure is_alive(&_g1h);
979 G1CopyingKeepAliveClosure keep_alive(&_g1h, pss);
980 G1EnqueueDiscoveredFieldClosure enqueue(&_g1h, pss);
981 G1ParEvacuateFollowersClosure complete_gc(&_g1h, pss, &_task_queues, _tm == RefProcThreadModel::Single ? nullptr : &_terminator, G1GCPhaseTimes::ObjCopy);
982 _rp_task->rp_work(worker_id, &is_alive, &keep_alive, &enqueue, &complete_gc);
983
984 // We have completed copying any necessary live referent objects.
985 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
986 }
987
988 void prepare_run_task_hook() override {
989 _terminator.reset_for_reuse(_queue_count);
990 }
991 };
992
993 void G1YoungCollector::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
994 Ticks start = Ticks::now();
995
996 ReferenceProcessor* rp = ref_processor_stw();
997 assert(rp->discovery_enabled(), "should have been enabled");
998
999 G1STWRefProcProxyTask task(rp->max_num_queues(), *_g1h, *per_thread_states, *task_queues());
1000 ReferenceProcessorPhaseTimes& pt = *phase_times()->ref_phase_times();
1001 ReferenceProcessorStats stats = rp->process_discovered_references(task, _g1h->workers(), pt);
1002
1003 gc_tracer_stw()->report_gc_reference_stats(stats);
1004
1005 _g1h->make_pending_list_reachable();
1006
1007 phase_times()->record_ref_proc_time((Ticks::now() - start).seconds() * MILLIUNITS);
1008 }
1009
1010 void G1YoungCollector::post_evacuate_cleanup_1(G1ParScanThreadStateSet* per_thread_states) {
1011 Ticks start = Ticks::now();
1012 {
1013 G1PostEvacuateCollectionSetCleanupTask1 cl(per_thread_states, &_evac_failure_regions);
1014 _g1h->run_batch_task(&cl);
1015 }
1016 phase_times()->record_post_evacuate_cleanup_task_1_time((Ticks::now() - start).seconds() * 1000.0);
1017 }
1018
1019 void G1YoungCollector::post_evacuate_cleanup_2(G1ParScanThreadStateSet* per_thread_states,
1020 G1EvacInfo* evacuation_info) {
1021 Ticks start = Ticks::now();
1022 {
1023 G1PostEvacuateCollectionSetCleanupTask2 cl(per_thread_states, evacuation_info, &_evac_failure_regions);
1024 _g1h->run_batch_task(&cl);
1025 }
1026 phase_times()->record_post_evacuate_cleanup_task_2_time((Ticks::now() - start).seconds() * 1000.0);
1027 }
1028
1029 void G1YoungCollector::enqueue_candidates_as_root_regions() {
1030 assert(collector_state()->is_in_concurrent_start_gc(), "must be");
1031
1032 G1CollectionSetCandidates* candidates = collection_set()->candidates();
1033 candidates->iterate_regions([&] (G1HeapRegion* r) {
1034 _g1h->concurrent_mark()->add_root_region(r);
1035 });
1036 }
1037
1038 void G1YoungCollector::post_evacuate_collection_set(G1EvacInfo* evacuation_info,
1039 G1ParScanThreadStateSet* per_thread_states) {
1040 G1GCPhaseTimes* p = phase_times();
1041
1042 // Process any discovered reference objects - we have
1043 // to do this _before_ we retire the GC alloc regions
1044 // as we may have to copy some 'reachable' referent
1045 // objects (and their reachable sub-graphs) that were
1046 // not copied during the pause.
1047 process_discovered_references(per_thread_states);
1048
1049 G1STWIsAliveClosure is_alive(_g1h);
1050 G1KeepAliveClosure keep_alive(_g1h);
1051
1052 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
1053
1054 allocator()->release_gc_alloc_regions(evacuation_info);
1055
1056 #if TASKQUEUE_STATS
1057 _g1h->task_queues()->print_and_reset_taskqueue_stats("Young GC");
1058 // Logging uses thread states, which are deleted by cleanup, so this must
1059 // be done before cleanup.
1060 per_thread_states->print_partial_array_task_stats();
1061 #endif // TASKQUEUE_STATS
1062
1063 post_evacuate_cleanup_1(per_thread_states);
1064
1065 post_evacuate_cleanup_2(per_thread_states, evacuation_info);
1066
1067 // Regions in the collection set candidates are roots for the marking (they are
1068 // not marked through considering they are very likely to be reclaimed soon.
1069 // They need to be enqueued explicitly compared to survivor regions.
1070 if (collector_state()->is_in_concurrent_start_gc()) {
1071 enqueue_candidates_as_root_regions();
1072 }
1073
1074 _evac_failure_regions.post_collection();
1075
1076 assert_used_and_recalculate_used_equal(_g1h);
1077
1078 _g1h->rebuild_free_region_list();
1079
1080 _g1h->record_obj_copy_mem_stats();
1081
1082 evacuation_info->set_bytes_used(_g1h->bytes_used_during_gc());
1083
1084 _g1h->prepare_for_mutator_after_young_collection();
1085
1086 _g1h->gc_epilogue(false);
1087
1088 _g1h->resize_heap_after_young_collection(_allocation_word_size);
1089 }
1090
1091 bool G1YoungCollector::evacuation_failed() const {
1092 return _evac_failure_regions.has_regions_evac_failed();
1093 }
1094
1095 bool G1YoungCollector::evacuation_pinned() const {
1096 return _evac_failure_regions.has_regions_evac_pinned();
1097 }
1098
1099 bool G1YoungCollector::evacuation_alloc_failed() const {
1100 return _evac_failure_regions.has_regions_alloc_failed();
1101 }
1102
1103 G1YoungCollector::G1YoungCollector(GCCause::Cause gc_cause,
1104 size_t allocation_word_size) :
1105 _g1h(G1CollectedHeap::heap()),
1106 _gc_cause(gc_cause),
1107 _allocation_word_size(allocation_word_size),
1108 _next_state(),
1109 _concurrent_operation_is_full_mark(false),
1110 _evac_failure_regions()
1111 {
1112 }
1113
1114 void G1YoungCollector::collect() {
1115 // Do timing/tracing/statistics/pre- and post-logging/verification work not
1116 // directly related to the collection. They should not be accounted for in
1117 // collection work timing.
1118
1119 // The G1YoungGCTraceTime message depends on collector state, so must come after
1120 // determining collector state.
1121 G1YoungGCTraceTime tm(this, _gc_cause);
1122
1123 // JFR
1124 G1YoungGCJFRTracerMark jtm(this);
1125 // JStat/MXBeans
1126 G1YoungGCMonitoringScope ms(monitoring_support(),
1127 !collection_set()->candidates()->is_empty() /* all_memory_pools_affected */);
1128 // Create the heap printer before internal pause timing to have
1129 // heap information printed as last part of detailed GC log.
1130 G1HeapPrinterMark hpm(_g1h);
1131 // Young GC internal pause timing
1132 G1YoungGCNotifyPauseMark npm(this);
1133
1134 // Verification may use the workers, so they must be set up before.
1135 // Individual parallel phases may override this.
1136 set_young_collection_default_active_worker_threads();
1137
1138 // Complete root region scan before moving any objects to preserve the SATB invariant.
1139 complete_root_region_scan();
1140
1141 G1YoungGCVerifierMark vm(this);
1142 {
1143 // Actual collection work starts and is executed (only) in this scope.
1144
1145 // Young GC internal collection timing. The elapsed time recorded in the
1146 // policy for the collection deliberately elides verification (and some
1147 // other trivial setup above).
1148 policy()->record_young_collection_start();
1149
1150 pre_evacuate_collection_set(jtm.evacuation_info());
1151
1152 G1ParScanThreadStateSet per_thread_states(_g1h,
1153 workers()->active_workers(),
1154 collection_set(),
1155 &_evac_failure_regions);
1156
1157 bool may_do_optional_evacuation = collection_set()->num_optional_regions() != 0;
1158 // Actually do the work...
1159 evacuate_initial_collection_set(&per_thread_states, may_do_optional_evacuation);
1160
1161 if (may_do_optional_evacuation) {
1162 evacuate_optional_collection_set(&per_thread_states);
1163 }
1164 post_evacuate_collection_set(jtm.evacuation_info(), &per_thread_states);
1165
1166 // Refine the type of a concurrent mark operation now that we did the
1167 // evacuation, eventually aborting it.
1168 _concurrent_operation_is_full_mark = policy()->concurrent_operation_is_full_mark("Revise IHOP", _allocation_word_size);
1169
1170 _next_state = policy()->record_young_collection_end(_concurrent_operation_is_full_mark, evacuation_alloc_failed(), _allocation_word_size);
1171 }
1172 }