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 // TypeArray objects are allowed to be reclaimed even if allocated before
332 // the start of concurrent mark. For this we rely on mark stack insertion
333 // to exclude is_typeArray() objects, preventing reclaiming an object
334 // that is in the mark stack. We also rely on the metadata for
335 // such objects to be built-in and so ensured to be kept live.
336 //
337 // Non-typeArrays that were allocated before marking are excluded from
338 // eager reclaim during marking. One issue is the problem described
339 // above with scrubbing the mark stack, but there is also a problem
340 // causing these humongous objects being collected incorrectly:
341 //
342 // E.g. if the mutator is running, we may have objects o1 and o2 in the same
343 // region, where o1 has already been scanned and o2 is only reachable by
344 // the candidate object h, which is humongous.
345 //
346 // If the mutator read the reference to o2 from h and installed it into o1,
347 // no remembered set entry would be created for keeping alive o2, as o1 and
348 // o2 are in the same region. Object h might be reclaimed by the next
349 // garbage collection. o1 still has the reference to o2, but since o1 had
350 // already been scanned we do not detect o2 to be still live and reclaim it.
351 //
352 // There is another minor problem with non-typeArray regions being the source
353 // of remembered set entries in other region's remembered sets. There are
354 // two cases: first, the remembered set entry is in a Free region after reclaim.
355 // We handle this case by ignoring these cards during merging the remembered
356 // sets.
357 //
358 // Second, there may be cases where eagerly reclaimed regions were already
359 // reallocated. This may cause scanning of these outdated remembered set
360 // entries, containing some objects. But apart from extra work this does
361 // not cause correctness issues.
362 // There is no difference between scanning cards covering an effectively
363 // dead humongous object vs. some other objects in reallocated regions.
364 //
365 // TAMSes are only reset after completing the entire mark cycle, during
366 // bitmap clearing. It is worth to not wait until then, and allow reclamation
367 // outside of actual (concurrent) SATB marking.
368 // This also applies to the concurrent start pause - we only set
369 // mark_in_progress() at the end of that GC: no mutator is running that can
370 // sneakily install a new reference to the potentially reclaimed humongous
371 // object.
372 // During the concurrent start pause the situation described above where we
373 // miss a reference can not happen. No mutator is modifying the object
374 // graph to install such an overlooked reference.
375 //
376 // After the pause, having reclaimed h, obviously the mutator can't fetch
377 // the reference from h any more.
378 if (!obj->is_typeArray()) {
379 // All regions that were allocated before marking have a TAMS != bottom.
380 bool allocated_before_mark_start = region->bottom() != _g1h->concurrent_mark()->top_at_mark_start(region);
381 bool mark_in_progress = _g1h->collector_state()->is_in_marking();
382
383 if (allocated_before_mark_start && mark_in_progress) {
384 return false;
385 }
386 }
387 return _g1h->is_potential_eager_reclaim_candidate(region);
388 }
389
390 public:
391 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
392 _g1h(g1h),
393 _parent_task(parent_task),
394 _worker_humongous_total(0),
395 _worker_humongous_candidates(0),
396 _humongous_card_set_stats() { }
397
398 ~G1PrepareRegionsClosure() {
399 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
400 _parent_task->add_humongous_total(_worker_humongous_total);
401 }
402
403 virtual bool do_heap_region(G1HeapRegion* hr) {
404 // First prepare the region for scanning
405 _g1h->rem_set()->prepare_region_for_scan(hr);
406
407 // Now check if region is a humongous candidate
408 if (!hr->is_starts_humongous()) {
409 _g1h->update_region_attr(hr);
410 return false;
411 }
412
413 uint index = hr->hrm_index();
414 if (humongous_region_is_candidate(hr)) {
415 _g1h->register_humongous_candidate_region_with_region_attr(index);
416 _worker_humongous_candidates++;
417 // We will later handle the remembered sets of these regions.
418 } else {
419 _g1h->update_region_attr(hr);
420 }
421
422 // Sample card set sizes for humongous regions before GC: this makes the policy
423 // to give back memory to the OS keep the most recent amount of memory for these regions.
424 _humongous_card_set_stats.add(hr->rem_set()->card_set_memory_stats());
425
426 log_debug(gc, humongous)("Humongous region %u (object size %zu @ " PTR_FORMAT ") remset %zu code roots %zu "
427 "marked %d pinned count %zu reclaim candidate %d type %s",
428 index,
429 cast_to_oop(hr->bottom())->size() * HeapWordSize,
430 p2i(hr->bottom()),
431 hr->rem_set()->occupied(),
432 hr->rem_set()->code_roots_list_length(),
433 _g1h->concurrent_mark()->mark_bitmap()->is_marked(hr->bottom()),
434 hr->pinned_count(),
435 _g1h->is_humongous_reclaim_candidate(index),
436 cast_to_oop(hr->bottom())->is_typeArray() ? "tA"
437 : (cast_to_oop(hr->bottom())->is_objArray() ? "oA" : "ob")
438 );
439 _worker_humongous_total++;
440
441 return false;
442 }
443
444 G1MonotonicArenaMemoryStats humongous_card_set_stats() const {
445 return _humongous_card_set_stats;
446 }
447 };
448
449 G1CollectedHeap* _g1h;
450 G1HeapRegionClaimer _claimer;
451 Atomic<uint> _humongous_total;
452 Atomic<uint> _humongous_candidates;
453
454 G1MonotonicArenaMemoryStats _all_card_set_stats;
455
456 public:
457 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
458 WorkerTask("Prepare Evacuation"),
459 _g1h(g1h),
460 _claimer(_g1h->workers()->active_workers()),
461 _humongous_total(0),
462 _humongous_candidates(0) { }
463
464 void work(uint worker_id) {
465 G1PrepareRegionsClosure cl(_g1h, this);
466 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
467
468 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
469 _all_card_set_stats.add(cl.humongous_card_set_stats());
470 }
471
472 void add_humongous_candidates(uint candidates) {
473 _humongous_candidates.add_then_fetch(candidates);
474 }
475
476 void add_humongous_total(uint total) {
477 _humongous_total.add_then_fetch(total);
478 }
479
480 uint humongous_candidates() {
481 return _humongous_candidates.load_relaxed();
482 }
483
484 uint humongous_total() {
485 return _humongous_total.load_relaxed();
486 }
487
488 const G1MonotonicArenaMemoryStats all_card_set_stats() const {
489 return _all_card_set_stats;
490 }
491 };
492
493 Tickspan G1YoungCollector::run_task_timed(WorkerTask* task) {
494 Ticks start = Ticks::now();
495 workers()->run_task(task);
496 return Ticks::now() - start;
497 }
498
499 void G1YoungCollector::set_young_collection_default_active_worker_threads(){
500 uint active_workers = WorkerPolicy::calc_active_workers(workers()->max_workers(),
501 workers()->active_workers(),
502 Threads::number_of_non_daemon_threads());
503 active_workers = workers()->set_active_workers(active_workers);
504 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->max_workers());
505 }
506
507 void G1YoungCollector::pre_evacuate_collection_set(G1EvacInfo* evacuation_info) {
508 // Flush various data in thread-local buffers to be able to determine the collection
509 // set
510 {
511 Ticks start = Ticks::now();
512 G1PreEvacuateCollectionSetBatchTask cl;
513 G1CollectedHeap::heap()->run_batch_task(&cl);
514 phase_times()->record_pre_evacuate_prepare_time_ms((Ticks::now() - start).seconds() * 1000.0);
515 }
516
517 // Needs log buffers flushed.
518 calculate_collection_set(evacuation_info, policy()->max_pause_time_ms());
519
520 if (collector_state()->is_in_concurrent_start_gc()) {
521 Ticks start = Ticks::now();
522 concurrent_mark()->pre_concurrent_start(_gc_cause);
523 phase_times()->record_prepare_concurrent_task_time_ms((Ticks::now() - start).seconds() * 1000.0);
524 }
525
526 // Please see comment in g1CollectedHeap.hpp and
527 // G1CollectedHeap::ref_processing_init() to see how
528 // reference processing currently works in G1.
529 ref_processor_stw()->start_discovery(false /* always_clear */);
530
531 _evac_failure_regions.pre_collection(_g1h->max_num_regions());
532
533 _g1h->gc_prologue(false);
534
535 // Initialize the GC alloc regions.
536 allocator()->init_gc_alloc_regions(evacuation_info);
537
538 {
539 Ticks start = Ticks::now();
540 rem_set()->prepare_for_scan_heap_roots();
541
542 _g1h->collection_set()->prepare_for_scan();
543
544 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
545 }
546
547 {
548 G1PrepareEvacuationTask g1_prep_task(_g1h);
549 Tickspan task_time = run_task_timed(&g1_prep_task);
550
551 G1MonotonicArenaMemoryStats sampled_card_set_stats = g1_prep_task.all_card_set_stats();
552 sampled_card_set_stats.add(_g1h->young_regions_cset_group()->card_set_memory_stats());
553 _g1h->set_young_gen_card_set_stats(sampled_card_set_stats);
554 _g1h->set_humongous_stats(g1_prep_task.humongous_total(), g1_prep_task.humongous_candidates());
555
556 phase_times()->record_register_regions(task_time.seconds() * 1000.0);
557 }
558
559 assert(_g1h->verifier()->check_region_attr_table(), "Inconsistency in the region attributes table.");
560
561 #if COMPILER2_OR_JVMCI
562 DerivedPointerTable::clear();
563 #endif
564
565 allocation_failure_injector()->arm_if_needed();
566 }
567
568 class G1ParEvacuateFollowersClosure : public VoidClosure {
569 double _start_term;
570 double _term_time;
571 size_t _term_attempts;
572
573 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
574 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
575
576 G1CollectedHeap* _g1h;
577 G1ParScanThreadState* _par_scan_state;
578 G1ScannerTasksQueueSet* _queues;
579 TaskTerminator* _terminator;
580 G1GCPhaseTimes::GCParPhases _phase;
581
582 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
583 G1ScannerTasksQueueSet* queues() { return _queues; }
584 TaskTerminator* terminator() { return _terminator; }
585
586 inline bool offer_termination() {
587 EventGCPhaseParallel event;
588 G1ParScanThreadState* const pss = par_scan_state();
589 start_term_time();
590 const bool res = (terminator() == nullptr) ? true : terminator()->offer_termination();
591 end_term_time();
592 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
593 return res;
594 }
595
596 public:
597 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
598 G1ParScanThreadState* par_scan_state,
599 G1ScannerTasksQueueSet* queues,
600 TaskTerminator* terminator,
601 G1GCPhaseTimes::GCParPhases phase)
602 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
603 _g1h(g1h), _par_scan_state(par_scan_state),
604 _queues(queues), _terminator(terminator), _phase(phase) {}
605
606 void do_void() {
607 EventGCPhaseParallel event;
608 G1ParScanThreadState* const pss = par_scan_state();
609 pss->trim_queue();
610 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
611 do {
612 EventGCPhaseParallel event;
613 pss->steal_and_trim_queue(queues());
614 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
615 } while (!offer_termination());
616 }
617
618 double term_time() const { return _term_time; }
619 size_t term_attempts() const { return _term_attempts; }
620 };
621
622 class G1EvacuateRegionsBaseTask : public WorkerTask {
623
624 // All pinned regions in the collection set must be registered as failed
625 // regions as there is no guarantee that there is a reference reachable by
626 // Java code (i.e. only by native code) that adds it to the evacuation failed
627 // regions.
628 void record_pinned_regions(G1ParScanThreadState* pss, uint worker_id) {
629 class RecordPinnedRegionClosure : public G1HeapRegionClosure {
630 G1ParScanThreadState* _pss;
631 uint _worker_id;
632
633 public:
634 RecordPinnedRegionClosure(G1ParScanThreadState* pss, uint worker_id) : _pss(pss), _worker_id(worker_id) { }
635
636 bool do_heap_region(G1HeapRegion* r) {
637 if (r->has_pinned_objects()) {
638 _pss->record_evacuation_failed_region(r, _worker_id, true /* cause_pinned */);
639 }
640 return false;
641 }
642 } cl(pss, worker_id);
643
644 _g1h->collection_set_iterate_increment_from(&cl, worker_id);
645 }
646
647 protected:
648 G1CollectedHeap* _g1h;
649 G1ParScanThreadStateSet* _per_thread_states;
650
651 G1ScannerTasksQueueSet* _task_queues;
652 TaskTerminator _terminator;
653
654 void evacuate_live_objects(G1ParScanThreadState* pss,
655 uint worker_id,
656 G1GCPhaseTimes::GCParPhases objcopy_phase,
657 G1GCPhaseTimes::GCParPhases termination_phase) {
658 G1GCPhaseTimes* p = _g1h->phase_times();
659
660 Ticks start = Ticks::now();
661 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
662 cl.do_void();
663
664 assert(pss->queue_is_empty(), "should be empty");
665
666 Tickspan evac_time = (Ticks::now() - start);
667 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
668
669 if (termination_phase == G1GCPhaseTimes::Termination) {
670 p->record_time_secs(termination_phase, worker_id, cl.term_time());
671 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
672 } else {
673 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
674 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
675 }
676 assert(pss->trim_ticks().value() == 0,
677 "Unexpected partial trimming during evacuation value " JLONG_FORMAT,
678 pss->trim_ticks().value());
679 }
680
681 virtual void start_work(uint worker_id) { }
682
683 virtual void end_work(uint worker_id) { }
684
685 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
686
687 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
688
689 private:
690 Atomic<bool> _pinned_regions_recorded;
691
692 public:
693 G1EvacuateRegionsBaseTask(const char* name,
694 G1ParScanThreadStateSet* per_thread_states,
695 G1ScannerTasksQueueSet* task_queues,
696 uint num_workers) :
697 WorkerTask(name),
698 _g1h(G1CollectedHeap::heap()),
699 _per_thread_states(per_thread_states),
700 _task_queues(task_queues),
701 _terminator(num_workers, _task_queues),
702 _pinned_regions_recorded(false)
703 { }
704
705 void work(uint worker_id) {
706 start_work(worker_id);
707
708 {
709 ResourceMark rm;
710
711 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
712 pss->set_ref_discoverer(_g1h->ref_processor_stw());
713
714 if (_pinned_regions_recorded.compare_set(false, true)) {
715 record_pinned_regions(pss, worker_id);
716 }
717 scan_roots(pss, worker_id);
718 evacuate_live_objects(pss, worker_id);
719 }
720
721 end_work(worker_id);
722 }
723 };
724
725 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
726 G1RootProcessor* _root_processor;
727 bool _has_optional_evacuation_work;
728
729 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
730 _root_processor->evacuate_roots(pss, worker_id);
731 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy, _has_optional_evacuation_work);
732 _g1h->rem_set()->scan_collection_set_code_roots(pss, worker_id, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
733 // There are no optional roots to scan right now.
734 #ifdef ASSERT
735 class VerifyOptionalCollectionSetRootsEmptyClosure : public G1HeapRegionClosure {
736 G1ParScanThreadState* _pss;
737
738 public:
739 VerifyOptionalCollectionSetRootsEmptyClosure(G1ParScanThreadState* pss) : _pss(pss) { }
740
741 bool do_heap_region(G1HeapRegion* r) override {
742 assert(!r->has_index_in_opt_cset(), "must be");
743 return false;
744 }
745 } cl(pss);
746 _g1h->collection_set_iterate_increment_from(&cl, worker_id);
747 #endif
748 }
749
750 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
751 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
752 }
753
754 void start_work(uint worker_id) {
755 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
756 }
757
758 void end_work(uint worker_id) {
759 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
760 }
761
762 public:
763 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
764 G1ParScanThreadStateSet* per_thread_states,
765 G1ScannerTasksQueueSet* task_queues,
766 G1RootProcessor* root_processor,
767 uint num_workers,
768 bool has_optional_evacuation_work) :
769 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
770 _root_processor(root_processor),
771 _has_optional_evacuation_work(has_optional_evacuation_work)
772 { }
773 };
774
775 void G1YoungCollector::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states,
776 bool has_optional_evacuation_work) {
777 G1GCPhaseTimes* p = phase_times();
778
779 rem_set()->merge_heap_roots(true /* initial_evacuation */);
780
781 Tickspan task_time;
782 const uint num_workers = workers()->active_workers();
783
784 Ticks start_processing = Ticks::now();
785 {
786 G1RootProcessor root_processor(_g1h, num_workers > 1 /* is_parallel */);
787 G1EvacuateRegionsTask g1_par_task(_g1h,
788 per_thread_states,
789 task_queues(),
790 &root_processor,
791 num_workers,
792 has_optional_evacuation_work);
793 task_time = run_task_timed(&g1_par_task);
794 // Closing the inner scope will execute the destructor for the
795 // G1RootProcessor object. By subtracting the WorkerThreads task from the total
796 // time of this scope, we get the "NMethod List Cleanup" time. This list is
797 // constructed during "STW two-phase nmethod root processing", see more in
798 // nmethod.hpp
799 }
800 Tickspan total_processing = Ticks::now() - start_processing;
801
802 p->record_initial_evac_time(task_time.seconds() * 1000.0);
803 p->record_or_add_nmethod_list_cleanup_time((total_processing - task_time).seconds() * 1000.0);
804
805 rem_set()->complete_evac_phase(has_optional_evacuation_work);
806 }
807
808 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
809
810 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
811 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy, true /* remember_already_scanned_cards */);
812 _g1h->rem_set()->scan_collection_set_code_roots(pss, worker_id, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
813 _g1h->rem_set()->scan_collection_set_optional_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::ObjCopy);
814 }
815
816 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
817 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
818 }
819
820 public:
821 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
822 G1ScannerTasksQueueSet* queues,
823 uint num_workers) :
824 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
825 }
826 };
827
828 void G1YoungCollector::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
829 Tickspan task_time;
830
831 Ticks start_processing = Ticks::now();
832 {
833 NMethodMarkingScope nmethod_marking_scope;
834 G1EvacuateOptionalRegionsTask task(per_thread_states, task_queues(), workers()->active_workers());
835 task_time = run_task_timed(&task);
836 // See comment in evacuate_initial_collection_set() for the reason of the scope.
837 }
838 Tickspan total_processing = Ticks::now() - start_processing;
839
840 G1GCPhaseTimes* p = phase_times();
841 p->record_or_add_optional_evac_time(task_time.seconds() * 1000.0);
842 p->record_or_add_nmethod_list_cleanup_time((total_processing - task_time).seconds() * 1000.0);
843 }
844
845 void G1YoungCollector::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
846 const double pause_start_time_ms = policy()->cur_pause_start_sec() * 1000.0;
847 double target_pause_time_ms = MaxGCPauseMillis;
848
849 if (G1ForceOptionalEvacuation) {
850 target_pause_time_ms = DBL_MAX;
851 }
852
853 while (!evacuation_alloc_failed() && collection_set()->num_optional_regions() > 0) {
854
855 double time_used_ms = os::elapsedTime() * 1000.0 - pause_start_time_ms;
856 double time_left_ms = target_pause_time_ms - time_used_ms;
857
858 if (time_left_ms <= 0 ||
859 !collection_set()->finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
860 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
861 collection_set()->num_optional_regions(), time_left_ms);
862 break;
863 }
864
865 rem_set()->merge_heap_roots(false /* initial_evacuation */);
866
867 evacuate_next_optional_regions(per_thread_states);
868
869 rem_set()->complete_evac_phase(true /* has_more_than_one_evacuation_phase */);
870 }
871
872 collection_set()->abandon_optional_collection_set(per_thread_states);
873 }
874
875 // Non Copying Keep Alive closure
876 class G1KeepAliveClosure: public OopClosure {
877 G1CollectedHeap*_g1h;
878 public:
879 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
880 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
881 void do_oop(oop* p) {
882 oop obj = *p;
883 assert(obj != nullptr, "the caller should have filtered out null values");
884
885 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
886 assert(!region_attr.is_humongous_candidate(), "Humongous candidates should never be considered alive");
887 if (region_attr.is_in_cset()) {
888 assert(obj->is_forwarded(), "invariant" );
889 *p = obj->forwardee();
890 }
891 }
892 };
893
894 // Copying Keep Alive closure - can be called from both
895 // serial and parallel code as long as different worker
896 // threads utilize different G1ParScanThreadState instances
897 // and different queues.
898 class G1CopyingKeepAliveClosure: public OopClosure {
899 G1CollectedHeap* _g1h;
900 G1ParScanThreadState* _par_scan_state;
901
902 public:
903 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
904 G1ParScanThreadState* pss):
905 _g1h(g1h),
906 _par_scan_state(pss)
907 {}
908
909 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
910 virtual void do_oop( oop* p) { do_oop_work(p); }
911
912 template <class T> void do_oop_work(T* p) {
913 oop obj = RawAccess<>::oop_load(p);
914
915 assert(!_g1h->region_attr(obj).is_humongous_candidate(), "Humongous candidates should never be considered alive");
916 if (_g1h->is_in_cset(obj)) {
917 // If the referent object has been forwarded (either copied
918 // to a new location or to itself in the event of an
919 // evacuation failure) then we need to update the reference
920 // field and, if both reference and referent are in the G1
921 // heap, update the RSet for the referent.
922 //
923 // If the referent has not been forwarded then we have to keep
924 // it alive by policy. Therefore we have copy the referent.
925 //
926 // When the queue is drained (after each phase of reference processing)
927 // the object and it's followers will be copied, the reference field set
928 // to point to the new location, and the RSet updated.
929 _par_scan_state->push_on_queue(ScannerTask(p));
930 }
931 }
932 };
933
934 class G1STWRefProcProxyTask : public RefProcProxyTask {
935 G1CollectedHeap& _g1h;
936 G1ParScanThreadStateSet& _pss;
937 TaskTerminator _terminator;
938 G1ScannerTasksQueueSet& _task_queues;
939
940 // G1 specific closure for marking discovered fields. Need to mark the card in the
941 // refinement table as the card table is in use by garbage collection.
942 class G1EnqueueDiscoveredFieldClosure : public EnqueueDiscoveredFieldClosure {
943 G1CollectedHeap* _g1h;
944 G1ParScanThreadState* _pss;
945
946 public:
947 G1EnqueueDiscoveredFieldClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : _g1h(g1h), _pss(pss) { }
948
949 void enqueue(HeapWord* discovered_field_addr, oop value) override {
950 assert(_g1h->is_in(discovered_field_addr), PTR_FORMAT " is not in heap ", p2i(discovered_field_addr));
951 // Store the value first, whatever it is.
952 RawAccess<>::oop_store(discovered_field_addr, value);
953 if (value == nullptr) {
954 return;
955 }
956 _pss->write_ref_field_post(discovered_field_addr, value);
957 }
958 };
959
960 public:
961 G1STWRefProcProxyTask(uint max_workers, G1CollectedHeap& g1h, G1ParScanThreadStateSet& pss, G1ScannerTasksQueueSet& task_queues)
962 : RefProcProxyTask("G1STWRefProcProxyTask", max_workers),
963 _g1h(g1h),
964 _pss(pss),
965 _terminator(max_workers, &task_queues),
966 _task_queues(task_queues) {}
967
968 void work(uint worker_id) override {
969 assert(worker_id < _max_workers, "sanity");
970 uint index = (_tm == RefProcThreadModel::Single) ? 0 : worker_id;
971
972 G1ParScanThreadState* pss = _pss.state_for_worker(index);
973 pss->set_ref_discoverer(nullptr);
974
975 G1STWIsAliveClosure is_alive(&_g1h);
976 G1CopyingKeepAliveClosure keep_alive(&_g1h, pss);
977 G1EnqueueDiscoveredFieldClosure enqueue(&_g1h, pss);
978 G1ParEvacuateFollowersClosure complete_gc(&_g1h, pss, &_task_queues, _tm == RefProcThreadModel::Single ? nullptr : &_terminator, G1GCPhaseTimes::ObjCopy);
979 _rp_task->rp_work(worker_id, &is_alive, &keep_alive, &enqueue, &complete_gc);
980
981 // We have completed copying any necessary live referent objects.
982 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
983 }
984
985 void prepare_run_task_hook() override {
986 _terminator.reset_for_reuse(_queue_count);
987 }
988 };
989
990 void G1YoungCollector::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
991 Ticks start = Ticks::now();
992
993 ReferenceProcessor* rp = ref_processor_stw();
994 assert(rp->discovery_enabled(), "should have been enabled");
995
996 G1STWRefProcProxyTask task(rp->max_num_queues(), *_g1h, *per_thread_states, *task_queues());
997 ReferenceProcessorPhaseTimes& pt = *phase_times()->ref_phase_times();
998 ReferenceProcessorStats stats = rp->process_discovered_references(task, _g1h->workers(), pt);
999
1000 gc_tracer_stw()->report_gc_reference_stats(stats);
1001
1002 _g1h->make_pending_list_reachable();
1003
1004 phase_times()->record_ref_proc_time((Ticks::now() - start).seconds() * MILLIUNITS);
1005 }
1006
1007 void G1YoungCollector::post_evacuate_cleanup_1(G1ParScanThreadStateSet* per_thread_states) {
1008 Ticks start = Ticks::now();
1009 {
1010 G1PostEvacuateCollectionSetCleanupTask1 cl(per_thread_states, &_evac_failure_regions);
1011 _g1h->run_batch_task(&cl);
1012 }
1013 phase_times()->record_post_evacuate_cleanup_task_1_time((Ticks::now() - start).seconds() * 1000.0);
1014 }
1015
1016 void G1YoungCollector::post_evacuate_cleanup_2(G1ParScanThreadStateSet* per_thread_states,
1017 G1EvacInfo* evacuation_info) {
1018 Ticks start = Ticks::now();
1019 {
1020 G1PostEvacuateCollectionSetCleanupTask2 cl(per_thread_states, evacuation_info, &_evac_failure_regions);
1021 _g1h->run_batch_task(&cl);
1022 }
1023 phase_times()->record_post_evacuate_cleanup_task_2_time((Ticks::now() - start).seconds() * 1000.0);
1024 }
1025
1026 void G1YoungCollector::enqueue_candidates_as_root_regions() {
1027 assert(collector_state()->is_in_concurrent_start_gc(), "must be");
1028
1029 G1CollectionSetCandidates* candidates = collection_set()->candidates();
1030 candidates->iterate_regions([&] (G1HeapRegion* r) {
1031 _g1h->concurrent_mark()->add_root_region(r);
1032 });
1033 }
1034
1035 void G1YoungCollector::post_evacuate_collection_set(G1EvacInfo* evacuation_info,
1036 G1ParScanThreadStateSet* per_thread_states) {
1037 G1GCPhaseTimes* p = phase_times();
1038
1039 // Process any discovered reference objects - we have
1040 // to do this _before_ we retire the GC alloc regions
1041 // as we may have to copy some 'reachable' referent
1042 // objects (and their reachable sub-graphs) that were
1043 // not copied during the pause.
1044 process_discovered_references(per_thread_states);
1045
1046 G1STWIsAliveClosure is_alive(_g1h);
1047 G1KeepAliveClosure keep_alive(_g1h);
1048
1049 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
1050
1051 allocator()->release_gc_alloc_regions(evacuation_info);
1052
1053 #if TASKQUEUE_STATS
1054 _g1h->task_queues()->print_and_reset_taskqueue_stats("Young GC");
1055 // Logging uses thread states, which are deleted by cleanup, so this must
1056 // be done before cleanup.
1057 per_thread_states->print_partial_array_task_stats();
1058 #endif // TASKQUEUE_STATS
1059
1060 post_evacuate_cleanup_1(per_thread_states);
1061
1062 post_evacuate_cleanup_2(per_thread_states, evacuation_info);
1063
1064 // Regions in the collection set candidates are roots for the marking (they are
1065 // not marked through considering they are very likely to be reclaimed soon.
1066 // They need to be enqueued explicitly compared to survivor regions.
1067 if (collector_state()->is_in_concurrent_start_gc()) {
1068 enqueue_candidates_as_root_regions();
1069 }
1070
1071 _evac_failure_regions.post_collection();
1072
1073 assert_used_and_recalculate_used_equal(_g1h);
1074
1075 _g1h->rebuild_free_region_list();
1076
1077 _g1h->record_obj_copy_mem_stats();
1078
1079 evacuation_info->set_bytes_used(_g1h->bytes_used_during_gc());
1080
1081 _g1h->prepare_for_mutator_after_young_collection();
1082
1083 _g1h->gc_epilogue(false);
1084
1085 _g1h->resize_heap_after_young_collection(_allocation_word_size);
1086 }
1087
1088 bool G1YoungCollector::evacuation_failed() const {
1089 return _evac_failure_regions.has_regions_evac_failed();
1090 }
1091
1092 bool G1YoungCollector::evacuation_pinned() const {
1093 return _evac_failure_regions.has_regions_evac_pinned();
1094 }
1095
1096 bool G1YoungCollector::evacuation_alloc_failed() const {
1097 return _evac_failure_regions.has_regions_alloc_failed();
1098 }
1099
1100 G1YoungCollector::G1YoungCollector(GCCause::Cause gc_cause,
1101 size_t allocation_word_size) :
1102 _g1h(G1CollectedHeap::heap()),
1103 _gc_cause(gc_cause),
1104 _allocation_word_size(allocation_word_size),
1105 _next_state(),
1106 _concurrent_operation_is_full_mark(false),
1107 _evac_failure_regions()
1108 {
1109 }
1110
1111 void G1YoungCollector::collect() {
1112 // Do timing/tracing/statistics/pre- and post-logging/verification work not
1113 // directly related to the collection. They should not be accounted for in
1114 // collection work timing.
1115
1116 // The G1YoungGCTraceTime message depends on collector state, so must come after
1117 // determining collector state.
1118 G1YoungGCTraceTime tm(this, _gc_cause);
1119
1120 // JFR
1121 G1YoungGCJFRTracerMark jtm(this);
1122 // JStat/MXBeans
1123 G1YoungGCMonitoringScope ms(monitoring_support(),
1124 !collection_set()->candidates()->is_empty() /* all_memory_pools_affected */);
1125 // Create the heap printer before internal pause timing to have
1126 // heap information printed as last part of detailed GC log.
1127 G1HeapPrinterMark hpm(_g1h);
1128 // Young GC internal pause timing
1129 G1YoungGCNotifyPauseMark npm(this);
1130
1131 // Verification may use the workers, so they must be set up before.
1132 // Individual parallel phases may override this.
1133 set_young_collection_default_active_worker_threads();
1134
1135 // Complete root region scan before moving any objects to preserve the SATB invariant.
1136 complete_root_region_scan();
1137
1138 G1YoungGCVerifierMark vm(this);
1139 {
1140 // Actual collection work starts and is executed (only) in this scope.
1141
1142 // Young GC internal collection timing. The elapsed time recorded in the
1143 // policy for the collection deliberately elides verification (and some
1144 // other trivial setup above).
1145 policy()->record_young_collection_start();
1146
1147 pre_evacuate_collection_set(jtm.evacuation_info());
1148
1149 G1ParScanThreadStateSet per_thread_states(_g1h,
1150 workers()->active_workers(),
1151 collection_set(),
1152 &_evac_failure_regions);
1153
1154 bool may_do_optional_evacuation = collection_set()->num_optional_regions() != 0;
1155 // Actually do the work...
1156 evacuate_initial_collection_set(&per_thread_states, may_do_optional_evacuation);
1157
1158 if (may_do_optional_evacuation) {
1159 evacuate_optional_collection_set(&per_thread_states);
1160 }
1161 post_evacuate_collection_set(jtm.evacuation_info(), &per_thread_states);
1162
1163 // Refine the type of a concurrent mark operation now that we did the
1164 // evacuation, eventually aborting it.
1165 _concurrent_operation_is_full_mark = policy()->concurrent_operation_is_full_mark("Revise IHOP", _allocation_word_size);
1166
1167 _next_state = policy()->record_young_collection_end(_concurrent_operation_is_full_mark, evacuation_alloc_failed(), _allocation_word_size);
1168 }
1169 }