1 /*
2 * Copyright (c) 2021, 2024, 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 #include "precompiled.hpp"
26
27 #include "classfile/classLoaderDataGraph.inline.hpp"
28 #include "classfile/javaClasses.inline.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.hpp"
35 #include "gc/g1/g1ConcurrentMark.hpp"
36 #include "gc/g1/g1GCPhaseTimes.hpp"
37 #include "gc/g1/g1EvacFailureRegions.inline.hpp"
38 #include "gc/g1/g1EvacInfo.hpp"
39 #include "gc/g1/g1HRPrinter.hpp"
40 #include "gc/g1/g1MonitoringSupport.hpp"
41 #include "gc/g1/g1ParScanThreadState.inline.hpp"
42 #include "gc/g1/g1Policy.hpp"
43 #include "gc/g1/g1RedirtyCardsQueue.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/g1/g1_globals.hpp"
53 #include "gc/shared/concurrentGCBreakpoints.hpp"
54 #include "gc/shared/gcTraceTime.inline.hpp"
55 #include "gc/shared/gcTimer.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/threads.hpp"
63 #include "utilities/ticks.hpp"
64
65 // GCTraceTime wrapper that constructs the message according to GC pause type and
66 // GC cause.
67 // The code relies on the fact that GCTraceTimeWrapper stores the string passed
68 // initially as a reference only, so that we can modify it as needed.
69 class G1YoungGCTraceTime {
70 G1YoungCollector* _collector;
71
72 G1GCPauseType _pause_type;
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 snprintf(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 snprintf(_young_gc_name_data,
93 MaxYoungGCNameLength,
94 "Pause Young (%s) (%s)%s",
95 G1GCPauseTypeHelper::to_string(_pause_type),
96 GCCause::to_string(_pause_cause),
97 evacuation_failed_string);
98 return _young_gc_name_data;
99 }
100
101 public:
102 G1YoungGCTraceTime(G1YoungCollector* collector, GCCause::Cause cause) :
103 _collector(collector),
104 // Take snapshot of current pause type at start as it may be modified during gc.
105 // The strings for all Concurrent Start pauses are the same, so the parameter
106 // does not matter here.
107 _pause_type(_collector->collector_state()->young_gc_pause_type(false /* concurrent_operation_is_full_mark */)),
108 _pause_cause(cause),
109 // Fake a "no cause" and manually add the correct string in update_young_gc_name()
110 // to make the string look more natural.
111 _tt(update_young_gc_name(), nullptr, GCCause::_no_gc, true) {
112 }
113
114 ~G1YoungGCTraceTime() {
115 update_young_gc_name();
116 }
117 };
118
119 class G1YoungGCNotifyPauseMark : public StackObj {
120 G1YoungCollector* _collector;
121
122 public:
123 G1YoungGCNotifyPauseMark(G1YoungCollector* collector) : _collector(collector) {
124 G1CollectedHeap::heap()->policy()->record_young_gc_pause_start();
125 }
126
127 ~G1YoungGCNotifyPauseMark() {
128 G1CollectedHeap::heap()->policy()->record_young_gc_pause_end(_collector->evacuation_failed());
129 }
130 };
131
132 class G1YoungGCJFRTracerMark : public G1JFRTracerMark {
133 G1EvacInfo _evacuation_info;
134
135 G1NewTracer* tracer() const { return (G1NewTracer*)_tracer; }
136
137 public:
138
139 G1EvacInfo* evacuation_info() { return &_evacuation_info; }
140
141 G1YoungGCJFRTracerMark(STWGCTimer* gc_timer_stw, G1NewTracer* gc_tracer_stw, GCCause::Cause cause) :
142 G1JFRTracerMark(gc_timer_stw, gc_tracer_stw), _evacuation_info() { }
143
144 void report_pause_type(G1GCPauseType type) {
145 tracer()->report_young_gc_pause(type);
146 }
147
148 ~G1YoungGCJFRTracerMark() {
149 G1CollectedHeap* g1h = G1CollectedHeap::heap();
150
151 tracer()->report_evacuation_info(&_evacuation_info);
152 tracer()->report_tenuring_threshold(g1h->policy()->tenuring_threshold());
153 }
154 };
155
156 class G1YoungGCVerifierMark : public StackObj {
157 G1YoungCollector* _collector;
158 G1HeapVerifier::G1VerifyType _type;
159
160 static G1HeapVerifier::G1VerifyType young_collection_verify_type() {
161 G1CollectorState* state = G1CollectedHeap::heap()->collector_state();
162 if (state->in_concurrent_start_gc()) {
163 return G1HeapVerifier::G1VerifyConcurrentStart;
164 } else if (state->in_young_only_phase()) {
165 return G1HeapVerifier::G1VerifyYoungNormal;
166 } else {
167 return G1HeapVerifier::G1VerifyMixed;
168 }
169 }
170
171 public:
172 G1YoungGCVerifierMark(G1YoungCollector* collector) : _collector(collector), _type(young_collection_verify_type()) {
173 G1CollectedHeap::heap()->verify_before_young_collection(_type);
174 }
175
176 ~G1YoungGCVerifierMark() {
177 // Inject evacuation failure tag into type if needed.
178 G1HeapVerifier::G1VerifyType type = _type;
179 if (_collector->evacuation_failed()) {
180 type = (G1HeapVerifier::G1VerifyType)(type | G1HeapVerifier::G1VerifyYoungEvacFail);
181 }
182 G1CollectedHeap::heap()->verify_after_young_collection(type);
183 }
184 };
185
186 G1Allocator* G1YoungCollector::allocator() const {
187 return _g1h->allocator();
188 }
189
190 G1CollectionSet* G1YoungCollector::collection_set() const {
191 return _g1h->collection_set();
192 }
193
194 G1CollectorState* G1YoungCollector::collector_state() const {
195 return _g1h->collector_state();
196 }
197
198 G1ConcurrentMark* G1YoungCollector::concurrent_mark() const {
199 return _g1h->concurrent_mark();
200 }
201
202 STWGCTimer* G1YoungCollector::gc_timer_stw() const {
203 return _g1h->gc_timer_stw();
204 }
205
206 G1NewTracer* G1YoungCollector::gc_tracer_stw() const {
207 return _g1h->gc_tracer_stw();
208 }
209
210 G1Policy* G1YoungCollector::policy() const {
211 return _g1h->policy();
212 }
213
214 G1GCPhaseTimes* G1YoungCollector::phase_times() const {
215 return _g1h->phase_times();
216 }
217
218 G1HRPrinter* G1YoungCollector::hr_printer() const {
219 return _g1h->hr_printer();
220 }
221
222 G1MonitoringSupport* G1YoungCollector::monitoring_support() const {
223 return _g1h->monitoring_support();
224 }
225
226 G1RemSet* G1YoungCollector::rem_set() const {
227 return _g1h->rem_set();
228 }
229
230 G1ScannerTasksQueueSet* G1YoungCollector::task_queues() const {
231 return _g1h->task_queues();
232 }
233
234 G1SurvivorRegions* G1YoungCollector::survivor_regions() const {
235 return _g1h->survivor();
236 }
237
238 ReferenceProcessor* G1YoungCollector::ref_processor_stw() const {
239 return _g1h->ref_processor_stw();
240 }
241
242 WorkerThreads* G1YoungCollector::workers() const {
243 return _g1h->workers();
244 }
245
246 G1YoungGCAllocationFailureInjector* G1YoungCollector::allocation_failure_injector() const {
247 return _g1h->allocation_failure_injector();
248 }
249
250
251 void G1YoungCollector::wait_for_root_region_scanning() {
252 Ticks start = Ticks::now();
253 // We have to wait until the CM threads finish scanning the
254 // root regions as it's the only way to ensure that all the
255 // objects on them have been correctly scanned before we start
256 // moving them during the GC.
257 bool waited = concurrent_mark()->wait_until_root_region_scan_finished();
258 Tickspan wait_time;
259 if (waited) {
260 wait_time = (Ticks::now() - start);
261 }
262 phase_times()->record_root_region_scan_wait_time(wait_time.seconds() * MILLIUNITS);
263 }
264
265 class G1PrintCollectionSetClosure : public HeapRegionClosure {
266 private:
267 G1HRPrinter* _hr_printer;
268 public:
269 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
270
271 virtual bool do_heap_region(HeapRegion* r) {
272 _hr_printer->cset(r);
273 return false;
274 }
275 };
276
277 void G1YoungCollector::calculate_collection_set(G1EvacInfo* evacuation_info, double target_pause_time_ms) {
278 // Forget the current allocation region (we might even choose it to be part
279 // of the collection set!) before finalizing the collection set.
280 allocator()->release_mutator_alloc_regions();
281
282 collection_set()->finalize_initial_collection_set(target_pause_time_ms, survivor_regions());
283 evacuation_info->set_collection_set_regions(collection_set()->region_length() +
284 collection_set()->optional_region_length());
285
286 concurrent_mark()->verify_no_collection_set_oops();
287
288 if (hr_printer()->is_active()) {
289 G1PrintCollectionSetClosure cl(hr_printer());
290 collection_set()->iterate(&cl);
291 collection_set()->iterate_optional(&cl);
292 }
293 }
294
295 class G1PrepareEvacuationTask : public WorkerTask {
296 class G1PrepareRegionsClosure : public HeapRegionClosure {
297 G1CollectedHeap* _g1h;
298 G1PrepareEvacuationTask* _parent_task;
299 uint _worker_humongous_total;
300 uint _worker_humongous_candidates;
301
302 G1MonotonicArenaMemoryStats _card_set_stats;
303
304 void sample_card_set_size(HeapRegion* hr) {
305 // Sample card set sizes for young gen and humongous before GC: this makes
306 // the policy to give back memory to the OS keep the most recent amount of
307 // memory for these regions.
308 if (hr->is_young() || hr->is_starts_humongous()) {
309 _card_set_stats.add(hr->rem_set()->card_set_memory_stats());
310 }
311 }
312
313 bool humongous_region_is_candidate(HeapRegion* region) const {
314 assert(region->is_starts_humongous(), "Must start a humongous object");
315
316 oop obj = cast_to_oop(region->bottom());
317
318 // Dead objects cannot be eager reclaim candidates. Due to class
319 // unloading it is unsafe to query their classes so we return early.
320 if (_g1h->is_obj_dead(obj, region)) {
321 return false;
322 }
323
324 // If we do not have a complete remembered set for the region, then we can
325 // not be sure that we have all references to it.
326 if (!region->rem_set()->is_complete()) {
327 return false;
328 }
329 // We also cannot collect the humongous object if it is pinned.
330 if (region->has_pinned_objects()) {
331 return false;
332 }
333 // Candidate selection must satisfy the following constraints
334 // while concurrent marking is in progress:
335 //
336 // * In order to maintain SATB invariants, an object must not be
337 // reclaimed if it was allocated before the start of marking and
338 // has not had its references scanned. Such an object must have
339 // its references (including type metadata) scanned to ensure no
340 // live objects are missed by the marking process. Objects
341 // allocated after the start of concurrent marking don't need to
342 // be scanned.
343 //
344 // * An object must not be reclaimed if it is on the concurrent
345 // mark stack. Objects allocated after the start of concurrent
346 // marking are never pushed on the mark stack.
347 //
348 // Nominating only objects allocated after the start of concurrent
349 // marking is sufficient to meet both constraints. This may miss
350 // some objects that satisfy the constraints, but the marking data
351 // structures don't support efficiently performing the needed
352 // additional tests or scrubbing of the mark stack.
353 //
354 // However, we presently only nominate is_typeArray() objects.
355 // A humongous object containing references induces remembered
356 // set entries on other regions. In order to reclaim such an
357 // object, those remembered sets would need to be cleaned up.
358 //
359 // We also treat is_typeArray() objects specially, allowing them
360 // to be reclaimed even if allocated before the start of
361 // concurrent mark. For this we rely on mark stack insertion to
362 // exclude is_typeArray() objects, preventing reclaiming an object
363 // that is in the mark stack. We also rely on the metadata for
364 // such objects to be built-in and so ensured to be kept live.
365 // Frequent allocation and drop of large binary blobs is an
366 // important use case for eager reclaim, and this special handling
367 // may reduce needed headroom.
368
369 return obj->is_typeArray() &&
370 _g1h->is_potential_eager_reclaim_candidate(region);
371 }
372
373 public:
374 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
375 _g1h(g1h),
376 _parent_task(parent_task),
377 _worker_humongous_total(0),
378 _worker_humongous_candidates(0) { }
379
380 ~G1PrepareRegionsClosure() {
381 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
382 _parent_task->add_humongous_total(_worker_humongous_total);
383 }
384
385 virtual bool do_heap_region(HeapRegion* hr) {
386 // First prepare the region for scanning
387 _g1h->rem_set()->prepare_region_for_scan(hr);
388
389 sample_card_set_size(hr);
390
391 // Now check if region is a humongous candidate
392 if (!hr->is_starts_humongous()) {
393 _g1h->register_region_with_region_attr(hr);
394 return false;
395 }
396
397 uint index = hr->hrm_index();
398 if (humongous_region_is_candidate(hr)) {
399 _g1h->register_humongous_candidate_region_with_region_attr(index);
400 _worker_humongous_candidates++;
401 // We will later handle the remembered sets of these regions.
402 } else {
403 _g1h->register_region_with_region_attr(hr);
404 }
405 log_debug(gc, humongous)("Humongous region %u (object size %zu @ " PTR_FORMAT ") remset %zu code roots %zu "
406 "marked %d pinned count %zu reclaim candidate %d type array %d",
407 index,
408 cast_to_oop(hr->bottom())->size() * HeapWordSize,
409 p2i(hr->bottom()),
410 hr->rem_set()->occupied(),
411 hr->rem_set()->code_roots_list_length(),
412 _g1h->concurrent_mark()->mark_bitmap()->is_marked(hr->bottom()),
413 hr->pinned_count(),
414 _g1h->is_humongous_reclaim_candidate(index),
415 cast_to_oop(hr->bottom())->is_typeArray()
416 );
417 _worker_humongous_total++;
418
419 return false;
420 }
421
422 G1MonotonicArenaMemoryStats card_set_stats() const {
423 return _card_set_stats;
424 }
425 };
426
427 G1CollectedHeap* _g1h;
428 HeapRegionClaimer _claimer;
429 volatile uint _humongous_total;
430 volatile uint _humongous_candidates;
431
432 G1MonotonicArenaMemoryStats _all_card_set_stats;
433
434 public:
435 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
436 WorkerTask("Prepare Evacuation"),
437 _g1h(g1h),
438 _claimer(_g1h->workers()->active_workers()),
439 _humongous_total(0),
440 _humongous_candidates(0) { }
441
442 void work(uint worker_id) {
443 G1PrepareRegionsClosure cl(_g1h, this);
444 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
445
446 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
447 _all_card_set_stats.add(cl.card_set_stats());
448 }
449
450 void add_humongous_candidates(uint candidates) {
451 Atomic::add(&_humongous_candidates, candidates);
452 }
453
454 void add_humongous_total(uint total) {
455 Atomic::add(&_humongous_total, total);
456 }
457
458 uint humongous_candidates() {
459 return _humongous_candidates;
460 }
461
462 uint humongous_total() {
463 return _humongous_total;
464 }
465
466 const G1MonotonicArenaMemoryStats all_card_set_stats() const {
467 return _all_card_set_stats;
468 }
469 };
470
471 Tickspan G1YoungCollector::run_task_timed(WorkerTask* task) {
472 Ticks start = Ticks::now();
473 workers()->run_task(task);
474 return Ticks::now() - start;
475 }
476
477 void G1YoungCollector::set_young_collection_default_active_worker_threads(){
478 uint active_workers = WorkerPolicy::calc_active_workers(workers()->max_workers(),
479 workers()->active_workers(),
480 Threads::number_of_non_daemon_threads());
481 active_workers = workers()->set_active_workers(active_workers);
482 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->max_workers());
483 }
484
485 void G1YoungCollector::pre_evacuate_collection_set(G1EvacInfo* evacuation_info) {
486 // Flush various data in thread-local buffers to be able to determine the collection
487 // set
488 {
489 Ticks start = Ticks::now();
490 G1PreEvacuateCollectionSetBatchTask cl;
491 G1CollectedHeap::heap()->run_batch_task(&cl);
492 phase_times()->record_pre_evacuate_prepare_time_ms((Ticks::now() - start).seconds() * 1000.0);
493 }
494
495 // Needs log buffers flushed.
496 calculate_collection_set(evacuation_info, policy()->max_pause_time_ms());
497
498 if (collector_state()->in_concurrent_start_gc()) {
499 concurrent_mark()->pre_concurrent_start(_gc_cause);
500 }
501
502 // Please see comment in g1CollectedHeap.hpp and
503 // G1CollectedHeap::ref_processing_init() to see how
504 // reference processing currently works in G1.
505 ref_processor_stw()->start_discovery(false /* always_clear */);
506
507 _evac_failure_regions.pre_collection(_g1h->max_reserved_regions());
508
509 _g1h->gc_prologue(false);
510
511 // Initialize the GC alloc regions.
512 allocator()->init_gc_alloc_regions(evacuation_info);
513
514 {
515 Ticks start = Ticks::now();
516 rem_set()->prepare_for_scan_heap_roots();
517 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
518 }
519
520 {
521 G1PrepareEvacuationTask g1_prep_task(_g1h);
522 Tickspan task_time = run_task_timed(&g1_prep_task);
523
524 _g1h->set_young_gen_card_set_stats(g1_prep_task.all_card_set_stats());
525 _g1h->set_humongous_stats(g1_prep_task.humongous_total(), g1_prep_task.humongous_candidates());
526
527 phase_times()->record_register_regions(task_time.seconds() * 1000.0);
528 }
529
530 assert(_g1h->verifier()->check_region_attr_table(), "Inconsistency in the region attributes table.");
531
532 #if COMPILER2_OR_JVMCI
533 DerivedPointerTable::clear();
534 #endif
535
536 allocation_failure_injector()->arm_if_needed();
537 }
538
539 class G1ParEvacuateFollowersClosure : public VoidClosure {
540 double _start_term;
541 double _term_time;
542 size_t _term_attempts;
543
544 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
545 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
546
547 G1CollectedHeap* _g1h;
548 G1ParScanThreadState* _par_scan_state;
549 G1ScannerTasksQueueSet* _queues;
550 TaskTerminator* _terminator;
551 G1GCPhaseTimes::GCParPhases _phase;
552
553 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
554 G1ScannerTasksQueueSet* queues() { return _queues; }
555 TaskTerminator* terminator() { return _terminator; }
556
557 inline bool offer_termination() {
558 EventGCPhaseParallel event;
559 G1ParScanThreadState* const pss = par_scan_state();
560 start_term_time();
561 const bool res = (terminator() == nullptr) ? true : terminator()->offer_termination();
562 end_term_time();
563 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
564 return res;
565 }
566
567 public:
568 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
569 G1ParScanThreadState* par_scan_state,
570 G1ScannerTasksQueueSet* queues,
571 TaskTerminator* terminator,
572 G1GCPhaseTimes::GCParPhases phase)
573 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
574 _g1h(g1h), _par_scan_state(par_scan_state),
575 _queues(queues), _terminator(terminator), _phase(phase) {}
576
577 void do_void() {
578 EventGCPhaseParallel event;
579 G1ParScanThreadState* const pss = par_scan_state();
580 pss->trim_queue();
581 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
582 do {
583 EventGCPhaseParallel event;
584 pss->steal_and_trim_queue(queues());
585 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
586 } while (!offer_termination());
587 }
588
589 double term_time() const { return _term_time; }
590 size_t term_attempts() const { return _term_attempts; }
591 };
592
593 class G1EvacuateRegionsBaseTask : public WorkerTask {
594 protected:
595 G1CollectedHeap* _g1h;
596 G1ParScanThreadStateSet* _per_thread_states;
597 G1ScannerTasksQueueSet* _task_queues;
598 TaskTerminator _terminator;
599 uint _num_workers;
600
601 void evacuate_live_objects(G1ParScanThreadState* pss,
602 uint worker_id,
603 G1GCPhaseTimes::GCParPhases objcopy_phase,
604 G1GCPhaseTimes::GCParPhases termination_phase) {
605 G1GCPhaseTimes* p = _g1h->phase_times();
606
607 Ticks start = Ticks::now();
608 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
609 cl.do_void();
610
611 assert(pss->queue_is_empty(), "should be empty");
612
613 Tickspan evac_time = (Ticks::now() - start);
614 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
615
616 if (termination_phase == G1GCPhaseTimes::Termination) {
617 p->record_time_secs(termination_phase, worker_id, cl.term_time());
618 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
619 } else {
620 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
621 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
622 }
623 assert(pss->trim_ticks().value() == 0,
624 "Unexpected partial trimming during evacuation value " JLONG_FORMAT,
625 pss->trim_ticks().value());
626 }
627
628 virtual void start_work(uint worker_id) { }
629
630 virtual void end_work(uint worker_id) { }
631
632 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
633
634 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
635
636 public:
637 G1EvacuateRegionsBaseTask(const char* name,
638 G1ParScanThreadStateSet* per_thread_states,
639 G1ScannerTasksQueueSet* task_queues,
640 uint num_workers) :
641 WorkerTask(name),
642 _g1h(G1CollectedHeap::heap()),
643 _per_thread_states(per_thread_states),
644 _task_queues(task_queues),
645 _terminator(num_workers, _task_queues),
646 _num_workers(num_workers)
647 { }
648
649 void work(uint worker_id) {
650 start_work(worker_id);
651
652 {
653 ResourceMark rm;
654
655 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
656 pss->set_ref_discoverer(_g1h->ref_processor_stw());
657
658 scan_roots(pss, worker_id);
659 evacuate_live_objects(pss, worker_id);
660 }
661
662 end_work(worker_id);
663 }
664 };
665
666 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
667 G1RootProcessor* _root_processor;
668 bool _has_optional_evacuation_work;
669
670 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
671 _root_processor->evacuate_roots(pss, worker_id);
672 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy, _has_optional_evacuation_work);
673 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
674 }
675
676 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
677 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
678 }
679
680 void start_work(uint worker_id) {
681 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
682 }
683
684 void end_work(uint worker_id) {
685 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
686 }
687
688 public:
689 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
690 G1ParScanThreadStateSet* per_thread_states,
691 G1ScannerTasksQueueSet* task_queues,
692 G1RootProcessor* root_processor,
693 uint num_workers,
694 bool has_optional_evacuation_work) :
695 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
696 _root_processor(root_processor),
697 _has_optional_evacuation_work(has_optional_evacuation_work)
698 { }
699 };
700
701 void G1YoungCollector::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states,
702 bool has_optional_evacuation_work) {
703 G1GCPhaseTimes* p = phase_times();
704
705 {
706 Ticks start = Ticks::now();
707 rem_set()->merge_heap_roots(true /* initial_evacuation */);
708 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
709 }
710
711 Tickspan task_time;
712 const uint num_workers = workers()->active_workers();
713
714 Ticks start_processing = Ticks::now();
715 {
716 G1RootProcessor root_processor(_g1h, num_workers);
717 G1EvacuateRegionsTask g1_par_task(_g1h,
718 per_thread_states,
719 task_queues(),
720 &root_processor,
721 num_workers,
722 has_optional_evacuation_work);
723 task_time = run_task_timed(&g1_par_task);
724 // Closing the inner scope will execute the destructor for the
725 // G1RootProcessor object. By subtracting the WorkerThreads task from the total
726 // time of this scope, we get the "NMethod List Cleanup" time. This list is
727 // constructed during "STW two-phase nmethod root processing", see more in
728 // nmethod.hpp
729 }
730 Tickspan total_processing = Ticks::now() - start_processing;
731
732 p->record_initial_evac_time(task_time.seconds() * 1000.0);
733 p->record_or_add_nmethod_list_cleanup_time((total_processing - task_time).seconds() * 1000.0);
734
735 rem_set()->complete_evac_phase(has_optional_evacuation_work);
736 }
737
738 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
739
740 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
741 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy, true /* remember_already_scanned_cards */);
742 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
743 }
744
745 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
746 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
747 }
748
749 public:
750 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
751 G1ScannerTasksQueueSet* queues,
752 uint num_workers) :
753 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
754 }
755 };
756
757 void G1YoungCollector::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
758 // To access the protected constructor/destructor
759 class G1MarkScope : public MarkScope { };
760
761 Tickspan task_time;
762
763 Ticks start_processing = Ticks::now();
764 {
765 G1MarkScope code_mark_scope;
766 G1EvacuateOptionalRegionsTask task(per_thread_states, task_queues(), workers()->active_workers());
767 task_time = run_task_timed(&task);
768 // See comment in evacuate_initial_collection_set() for the reason of the scope.
769 }
770 Tickspan total_processing = Ticks::now() - start_processing;
771
772 G1GCPhaseTimes* p = phase_times();
773 p->record_or_add_nmethod_list_cleanup_time((total_processing - task_time).seconds() * 1000.0);
774 }
775
776 void G1YoungCollector::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
777 const double collection_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
778
779 while (!evacuation_alloc_failed() && collection_set()->optional_region_length() > 0) {
780
781 double time_used_ms = os::elapsedTime() * 1000.0 - collection_start_time_ms;
782 double time_left_ms = MaxGCPauseMillis - time_used_ms;
783
784 if (time_left_ms < 0 ||
785 !collection_set()->finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
786 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
787 collection_set()->optional_region_length(), time_left_ms);
788 break;
789 }
790
791 {
792 Ticks start = Ticks::now();
793 rem_set()->merge_heap_roots(false /* initial_evacuation */);
794 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
795 }
796
797 {
798 Ticks start = Ticks::now();
799 evacuate_next_optional_regions(per_thread_states);
800 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
801 }
802
803 rem_set()->complete_evac_phase(true /* has_more_than_one_evacuation_phase */);
804 }
805
806 collection_set()->abandon_optional_collection_set(per_thread_states);
807 }
808
809 // Non Copying Keep Alive closure
810 class G1KeepAliveClosure: public OopClosure {
811 G1CollectedHeap*_g1h;
812 public:
813 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
814 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
815 void do_oop(oop* p) {
816 oop obj = *p;
817 assert(obj != nullptr, "the caller should have filtered out null values");
818
819 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
820 if (!region_attr.is_in_cset_or_humongous_candidate()) {
821 return;
822 }
823 if (region_attr.is_in_cset()) {
824 assert(obj->is_forwarded(), "invariant" );
825 *p = obj->forwardee();
826 } else {
827 assert(!obj->is_forwarded(), "invariant" );
828 assert(region_attr.is_humongous_candidate(),
829 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
830 _g1h->set_humongous_is_live(obj);
831 }
832 }
833 };
834
835 // Copying Keep Alive closure - can be called from both
836 // serial and parallel code as long as different worker
837 // threads utilize different G1ParScanThreadState instances
838 // and different queues.
839 class G1CopyingKeepAliveClosure: public OopClosure {
840 G1CollectedHeap* _g1h;
841 G1ParScanThreadState* _par_scan_state;
842
843 public:
844 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
845 G1ParScanThreadState* pss):
846 _g1h(g1h),
847 _par_scan_state(pss)
848 {}
849
850 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
851 virtual void do_oop( oop* p) { do_oop_work(p); }
852
853 template <class T> void do_oop_work(T* p) {
854 oop obj = RawAccess<>::oop_load(p);
855
856 if (_g1h->is_in_cset_or_humongous_candidate(obj)) {
857 // If the referent object has been forwarded (either copied
858 // to a new location or to itself in the event of an
859 // evacuation failure) then we need to update the reference
860 // field and, if both reference and referent are in the G1
861 // heap, update the RSet for the referent.
862 //
863 // If the referent has not been forwarded then we have to keep
864 // it alive by policy. Therefore we have copy the referent.
865 //
866 // When the queue is drained (after each phase of reference processing)
867 // the object and it's followers will be copied, the reference field set
868 // to point to the new location, and the RSet updated.
869 _par_scan_state->push_on_queue(ScannerTask(p));
870 }
871 }
872 };
873
874 class G1STWRefProcProxyTask : public RefProcProxyTask {
875 G1CollectedHeap& _g1h;
876 G1ParScanThreadStateSet& _pss;
877 TaskTerminator _terminator;
878 G1ScannerTasksQueueSet& _task_queues;
879
880 // Special closure for enqueuing discovered fields: during enqueue the card table
881 // may not be in shape to properly handle normal barrier calls (e.g. card marks
882 // in regions that failed evacuation, scribbling of various values by card table
883 // scan code). Additionally the regular barrier enqueues into the "global"
884 // DCQS, but during GC we need these to-be-refined entries in the GC local queue
885 // so that after clearing the card table, the redirty cards phase will properly
886 // mark all dirty cards to be picked up by refinement.
887 class G1EnqueueDiscoveredFieldClosure : public EnqueueDiscoveredFieldClosure {
888 G1CollectedHeap* _g1h;
889 G1ParScanThreadState* _pss;
890
891 public:
892 G1EnqueueDiscoveredFieldClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : _g1h(g1h), _pss(pss) { }
893
894 void enqueue(HeapWord* discovered_field_addr, oop value) override {
895 assert(_g1h->is_in(discovered_field_addr), PTR_FORMAT " is not in heap ", p2i(discovered_field_addr));
896 // Store the value first, whatever it is.
897 RawAccess<>::oop_store(discovered_field_addr, value);
898 if (value == nullptr) {
899 return;
900 }
901 _pss->write_ref_field_post(discovered_field_addr, value);
902 }
903 };
904
905 public:
906 G1STWRefProcProxyTask(uint max_workers, G1CollectedHeap& g1h, G1ParScanThreadStateSet& pss, G1ScannerTasksQueueSet& task_queues)
907 : RefProcProxyTask("G1STWRefProcProxyTask", max_workers),
908 _g1h(g1h),
909 _pss(pss),
910 _terminator(max_workers, &task_queues),
911 _task_queues(task_queues) {}
912
913 void work(uint worker_id) override {
914 assert(worker_id < _max_workers, "sanity");
915 uint index = (_tm == RefProcThreadModel::Single) ? 0 : worker_id;
916
917 G1ParScanThreadState* pss = _pss.state_for_worker(index);
918 pss->set_ref_discoverer(nullptr);
919
920 G1STWIsAliveClosure is_alive(&_g1h);
921 G1CopyingKeepAliveClosure keep_alive(&_g1h, pss);
922 G1EnqueueDiscoveredFieldClosure enqueue(&_g1h, pss);
923 G1ParEvacuateFollowersClosure complete_gc(&_g1h, pss, &_task_queues, _tm == RefProcThreadModel::Single ? nullptr : &_terminator, G1GCPhaseTimes::ObjCopy);
924 _rp_task->rp_work(worker_id, &is_alive, &keep_alive, &enqueue, &complete_gc);
925
926 // We have completed copying any necessary live referent objects.
927 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
928 }
929
930 void prepare_run_task_hook() override {
931 _terminator.reset_for_reuse(_queue_count);
932 }
933 };
934
935 void G1YoungCollector::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
936 Ticks start = Ticks::now();
937
938 ReferenceProcessor* rp = ref_processor_stw();
939 assert(rp->discovery_enabled(), "should have been enabled");
940
941 uint no_of_gc_workers = workers()->active_workers();
942 rp->set_active_mt_degree(no_of_gc_workers);
943
944 G1STWRefProcProxyTask task(rp->max_num_queues(), *_g1h, *per_thread_states, *task_queues());
945 ReferenceProcessorPhaseTimes& pt = *phase_times()->ref_phase_times();
946 ReferenceProcessorStats stats = rp->process_discovered_references(task, pt);
947
948 gc_tracer_stw()->report_gc_reference_stats(stats);
949
950 _g1h->make_pending_list_reachable();
951
952 phase_times()->record_ref_proc_time((Ticks::now() - start).seconds() * MILLIUNITS);
953 }
954
955 void G1YoungCollector::post_evacuate_cleanup_1(G1ParScanThreadStateSet* per_thread_states) {
956 Ticks start = Ticks::now();
957 {
958 G1PostEvacuateCollectionSetCleanupTask1 cl(per_thread_states, &_evac_failure_regions);
959 _g1h->run_batch_task(&cl);
960 }
961 phase_times()->record_post_evacuate_cleanup_task_1_time((Ticks::now() - start).seconds() * 1000.0);
962 }
963
964 void G1YoungCollector::post_evacuate_cleanup_2(G1ParScanThreadStateSet* per_thread_states,
965 G1EvacInfo* evacuation_info) {
966 Ticks start = Ticks::now();
967 {
968 G1PostEvacuateCollectionSetCleanupTask2 cl(per_thread_states, evacuation_info, &_evac_failure_regions);
969 _g1h->run_batch_task(&cl);
970 }
971 phase_times()->record_post_evacuate_cleanup_task_2_time((Ticks::now() - start).seconds() * 1000.0);
972 }
973
974 void G1YoungCollector::enqueue_candidates_as_root_regions() {
975 assert(collector_state()->in_concurrent_start_gc(), "must be");
976
977 G1CollectionSetCandidates* candidates = collection_set()->candidates();
978 for (HeapRegion* r : *candidates) {
979 _g1h->concurrent_mark()->add_root_region(r);
980 }
981 }
982
983 void G1YoungCollector::post_evacuate_collection_set(G1EvacInfo* evacuation_info,
984 G1ParScanThreadStateSet* per_thread_states) {
985 G1GCPhaseTimes* p = phase_times();
986
987 // Process any discovered reference objects - we have
988 // to do this _before_ we retire the GC alloc regions
989 // as we may have to copy some 'reachable' referent
990 // objects (and their reachable sub-graphs) that were
991 // not copied during the pause.
992 process_discovered_references(per_thread_states);
993
994 G1STWIsAliveClosure is_alive(_g1h);
995 G1KeepAliveClosure keep_alive(_g1h);
996
997 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
998
999 allocator()->release_gc_alloc_regions(evacuation_info);
1000
1001 post_evacuate_cleanup_1(per_thread_states);
1002
1003 post_evacuate_cleanup_2(per_thread_states, evacuation_info);
1004
1005 // Regions in the collection set candidates are roots for the marking (they are
1006 // not marked through considering they are very likely to be reclaimed soon.
1007 // They need to be enqueued explicitly compared to survivor regions.
1008 if (collector_state()->in_concurrent_start_gc()) {
1009 enqueue_candidates_as_root_regions();
1010 }
1011
1012 _evac_failure_regions.post_collection();
1013
1014 assert_used_and_recalculate_used_equal(_g1h);
1015
1016 _g1h->rebuild_free_region_list();
1017
1018 _g1h->record_obj_copy_mem_stats();
1019
1020 evacuation_info->set_bytes_used(_g1h->bytes_used_during_gc());
1021
1022 _g1h->prepare_for_mutator_after_young_collection();
1023
1024 _g1h->gc_epilogue(false);
1025
1026 _g1h->expand_heap_after_young_collection();
1027 }
1028
1029 bool G1YoungCollector::evacuation_failed() const {
1030 return _evac_failure_regions.has_regions_evac_failed();
1031 }
1032
1033 bool G1YoungCollector::evacuation_pinned() const {
1034 return _evac_failure_regions.has_regions_evac_pinned();
1035 }
1036
1037 bool G1YoungCollector::evacuation_alloc_failed() const {
1038 return _evac_failure_regions.has_regions_alloc_failed();
1039 }
1040
1041 G1YoungCollector::G1YoungCollector(GCCause::Cause gc_cause) :
1042 _g1h(G1CollectedHeap::heap()),
1043 _gc_cause(gc_cause),
1044 _concurrent_operation_is_full_mark(false),
1045 _evac_failure_regions()
1046 {
1047 }
1048
1049 void G1YoungCollector::collect() {
1050 // Do timing/tracing/statistics/pre- and post-logging/verification work not
1051 // directly related to the collection. They should not be accounted for in
1052 // collection work timing.
1053
1054 // The G1YoungGCTraceTime message depends on collector state, so must come after
1055 // determining collector state.
1056 G1YoungGCTraceTime tm(this, _gc_cause);
1057
1058 // JFR
1059 G1YoungGCJFRTracerMark jtm(gc_timer_stw(), gc_tracer_stw(), _gc_cause);
1060 // JStat/MXBeans
1061 G1YoungGCMonitoringScope ms(monitoring_support(),
1062 !collection_set()->candidates()->is_empty() /* all_memory_pools_affected */);
1063 // Create the heap printer before internal pause timing to have
1064 // heap information printed as last part of detailed GC log.
1065 G1HeapPrinterMark hpm(_g1h);
1066 // Young GC internal pause timing
1067 G1YoungGCNotifyPauseMark npm(this);
1068
1069 // Verification may use the workers, so they must be set up before.
1070 // Individual parallel phases may override this.
1071 set_young_collection_default_active_worker_threads();
1072
1073 // Wait for root region scan here to make sure that it is done before any
1074 // use of the STW workers to maximize cpu use (i.e. all cores are available
1075 // just to do that).
1076 wait_for_root_region_scanning();
1077
1078 G1YoungGCVerifierMark vm(this);
1079 {
1080 // Actual collection work starts and is executed (only) in this scope.
1081
1082 // Young GC internal collection timing. The elapsed time recorded in the
1083 // policy for the collection deliberately elides verification (and some
1084 // other trivial setup above).
1085 policy()->record_young_collection_start();
1086
1087 pre_evacuate_collection_set(jtm.evacuation_info());
1088
1089 G1ParScanThreadStateSet per_thread_states(_g1h,
1090 workers()->active_workers(),
1091 collection_set(),
1092 &_evac_failure_regions);
1093
1094 bool may_do_optional_evacuation = collection_set()->optional_region_length() != 0;
1095 // Actually do the work...
1096 evacuate_initial_collection_set(&per_thread_states, may_do_optional_evacuation);
1097
1098 if (may_do_optional_evacuation) {
1099 evacuate_optional_collection_set(&per_thread_states);
1100 }
1101 post_evacuate_collection_set(jtm.evacuation_info(), &per_thread_states);
1102
1103 // Refine the type of a concurrent mark operation now that we did the
1104 // evacuation, eventually aborting it.
1105 _concurrent_operation_is_full_mark = policy()->concurrent_operation_is_full_mark("Revise IHOP");
1106
1107 // Need to report the collection pause now since record_collection_pause_end()
1108 // modifies it to the next state.
1109 jtm.report_pause_type(collector_state()->young_gc_pause_type(_concurrent_operation_is_full_mark));
1110
1111 policy()->record_young_collection_end(_concurrent_operation_is_full_mark, evacuation_alloc_failed());
1112 }
1113 TASKQUEUE_STATS_ONLY(_g1h->task_queues()->print_and_reset_taskqueue_stats("Oop Queue");)
1114 }