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 "compiler/oopMap.hpp"
27 #include "cppstdlib/new.hpp"
28 #include "gc/g1/g1CardSetMemory.hpp"
29 #include "gc/g1/g1CardTableEntryClosure.hpp"
30 #include "gc/g1/g1CollectedHeap.inline.hpp"
31 #include "gc/g1/g1CollectionSetCandidates.inline.hpp"
32 #include "gc/g1/g1CollectorState.inline.hpp"
33 #include "gc/g1/g1ConcurrentMark.inline.hpp"
34 #include "gc/g1/g1EvacFailureRegions.inline.hpp"
35 #include "gc/g1/g1EvacInfo.hpp"
36 #include "gc/g1/g1EvacStats.inline.hpp"
37 #include "gc/g1/g1HeapRegion.inline.hpp"
38 #include "gc/g1/g1HeapRegionPrinter.hpp"
39 #include "gc/g1/g1HeapRegionRemSet.inline.hpp"
40 #include "gc/g1/g1OopClosures.inline.hpp"
41 #include "gc/g1/g1ParScanThreadState.hpp"
42 #include "gc/g1/g1RemSet.hpp"
43 #include "gc/g1/g1YoungGCPostEvacuateTasks.hpp"
44 #include "gc/shared/bufferNode.hpp"
45 #include "gc/shared/partialArrayState.hpp"
46 #include "jfr/jfrEvents.hpp"
47 #include "oops/access.inline.hpp"
48 #include "oops/compressedOops.inline.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "runtime/atomic.hpp"
51 #include "runtime/prefetch.inline.hpp"
52 #include "runtime/threads.hpp"
53 #include "runtime/threadSMR.hpp"
54 #include "utilities/bitMap.inline.hpp"
55 #include "utilities/ticks.hpp"
56
57 class G1PostEvacuateCollectionSetCleanupTask1::MergePssTask : public G1AbstractSubTask {
58 G1ParScanThreadStateSet* _per_thread_states;
59
60 public:
61 MergePssTask(G1ParScanThreadStateSet* per_thread_states) :
62 G1AbstractSubTask(G1GCPhaseTimes::MergePSS),
63 _per_thread_states(per_thread_states) { }
64
65 double worker_cost() const override { return 1.0; }
66
67 void do_work(uint worker_id) override { _per_thread_states->flush_stats(); }
68 };
69
70 class G1PostEvacuateCollectionSetCleanupTask1::RecalculateUsedTask : public G1AbstractSubTask {
71 bool _evacuation_failed;
72 bool _allocation_failed;
73
74 public:
75 RecalculateUsedTask(bool evacuation_failed, bool allocation_failed) :
76 G1AbstractSubTask(G1GCPhaseTimes::RecalculateUsed),
77 _evacuation_failed(evacuation_failed),
78 _allocation_failed(allocation_failed) { }
79
80 double worker_cost() const override {
81 // If there is no evacuation failure, the work to perform is minimal.
82 return _evacuation_failed ? 1.0 : AlmostNoWork;
83 }
84
85 void do_work(uint worker_id) override {
86 G1CollectedHeap::heap()->update_used_after_gc(_evacuation_failed);
87 if (_allocation_failed) {
88 // Reset the G1GCAllocationFailureALot counters and flags
89 G1CollectedHeap::heap()->allocation_failure_injector()->reset();
90 }
91 }
92 };
93
94 class G1PostEvacuateCollectionSetCleanupTask1::SampleCollectionSetCandidatesTask : public G1AbstractSubTask {
95 public:
96 SampleCollectionSetCandidatesTask() : G1AbstractSubTask(G1GCPhaseTimes::SampleCollectionSetCandidates) { }
97
98 static bool should_execute() {
99 return G1CollectedHeap::heap()->should_sample_collection_set_candidates();
100 }
101
102 double worker_cost() const override {
103 return should_execute() ? 1.0 : AlmostNoWork;
104 }
105
106 void do_work(uint worker_id) override {
107 G1CollectedHeap* g1h = G1CollectedHeap::heap();
108
109 G1MonotonicArenaMemoryStats _total;
110 G1CollectionSetCandidates* candidates = g1h->collection_set()->candidates();
111 for (G1CSetCandidateGroup* gr : candidates->from_marking_groups()) {
112 _total.add(gr->card_set_memory_stats());
113 }
114
115 for (G1CSetCandidateGroup* gr : candidates->retained_groups()) {
116 _total.add(gr->card_set_memory_stats());
117 }
118 g1h->set_collection_set_candidates_stats(_total);
119 }
120 };
121
122 class G1PostEvacuateCollectionSetCleanupTask1::RestoreEvacFailureRegionsTask : public G1AbstractSubTask {
123 G1CollectedHeap* _g1h;
124 G1ConcurrentMark* _cm;
125
126 G1EvacFailureRegions* _evac_failure_regions;
127 CHeapBitMap _chunk_bitmap;
128
129 uint _num_chunks_per_region;
130 uint _num_evac_fail_regions;
131 size_t _chunk_size;
132
133 class PhaseTimesStat {
134 static constexpr G1GCPhaseTimes::GCParPhases phase_name =
135 G1GCPhaseTimes::RemoveSelfForwards;
136
137 G1GCPhaseTimes* _phase_times;
138 uint _worker_id;
139 Ticks _start;
140
141 public:
142 PhaseTimesStat(G1GCPhaseTimes* phase_times, uint worker_id) :
143 _phase_times(phase_times),
144 _worker_id(worker_id),
145 _start(Ticks::now()) { }
146
147 ~PhaseTimesStat() {
148 _phase_times->record_or_add_time_secs(phase_name,
149 _worker_id,
150 (Ticks::now() - _start).seconds());
151 }
152
153 void register_empty_chunk() {
154 _phase_times->record_or_add_thread_work_item(phase_name,
155 _worker_id,
156 1,
157 G1GCPhaseTimes::RemoveSelfForwardEmptyChunksNum);
158 }
159
160 void register_nonempty_chunk() {
161 _phase_times->record_or_add_thread_work_item(phase_name,
162 _worker_id,
163 1,
164 G1GCPhaseTimes::RemoveSelfForwardChunksNum);
165 }
166
167 void register_objects_count_and_size(size_t num_marked_obj, size_t marked_words) {
168 _phase_times->record_or_add_thread_work_item(phase_name,
169 _worker_id,
170 num_marked_obj,
171 G1GCPhaseTimes::RemoveSelfForwardObjectsNum);
172
173 size_t marked_bytes = marked_words * HeapWordSize;
174 _phase_times->record_or_add_thread_work_item(phase_name,
175 _worker_id,
176 marked_bytes,
177 G1GCPhaseTimes::RemoveSelfForwardObjectsBytes);
178 }
179 };
180
181 // Fill the memory area from start to end with filler objects, and update the BOT
182 // accordingly. Since we clear and use the bitmap for marking objects that failed
183 // evacuation, there is no other work to be done there.
184 static size_t zap_dead_objects(G1HeapRegion* hr, HeapWord* start, HeapWord* end) {
185 assert(start <= end, "precondition");
186 if (start == end) {
187 return 0;
188 }
189
190 hr->fill_range_with_dead_objects(start, end);
191 return pointer_delta(end, start);
192 }
193
194 static void update_garbage_words_in_hr(G1HeapRegion* hr, size_t garbage_words) {
195 if (garbage_words != 0) {
196 hr->note_self_forward_chunk_done(garbage_words * HeapWordSize);
197 }
198 }
199
200 static void prefetch_obj(HeapWord* obj_addr) {
201 Prefetch::write(obj_addr, PrefetchScanIntervalInBytes);
202 }
203
204 bool claim_chunk(uint chunk_idx) {
205 return _chunk_bitmap.par_set_bit(chunk_idx);
206 }
207
208 void process_chunk(uint worker_id, uint chunk_idx) {
209 PhaseTimesStat stat(_g1h->phase_times(), worker_id);
210
211 G1CMBitMap* bitmap = _cm->mark_bitmap();
212 const uint region_idx = _evac_failure_regions->get_region_idx(chunk_idx / _num_chunks_per_region);
213 G1HeapRegion* hr = _g1h->region_at(region_idx);
214
215 HeapWord* hr_bottom = hr->bottom();
216 HeapWord* hr_top = hr->top();
217 HeapWord* chunk_start = hr_bottom + (chunk_idx % _num_chunks_per_region) * _chunk_size;
218
219 assert(chunk_start < hr->end(), "inv");
220 if (chunk_start >= hr_top) {
221 return;
222 }
223
224 HeapWord* chunk_end = MIN2(chunk_start + _chunk_size, hr_top);
225 HeapWord* first_marked_addr = bitmap->get_next_marked_addr(chunk_start, hr_top);
226
227 size_t garbage_words = 0;
228
229 if (chunk_start == hr_bottom) {
230 // This is the bottom-most chunk in this region; zap [bottom, first_marked_addr).
231 garbage_words += zap_dead_objects(hr, hr_bottom, first_marked_addr);
232 }
233
234 if (first_marked_addr >= chunk_end) {
235 stat.register_empty_chunk();
236 update_garbage_words_in_hr(hr, garbage_words);
237 return;
238 }
239
240 stat.register_nonempty_chunk();
241
242 size_t num_marked_objs = 0;
243 size_t marked_words = 0;
244
245 HeapWord* obj_addr = first_marked_addr;
246 assert(chunk_start <= obj_addr && obj_addr < chunk_end,
247 "object " PTR_FORMAT " must be within chunk [" PTR_FORMAT ", " PTR_FORMAT "[",
248 p2i(obj_addr), p2i(chunk_start), p2i(chunk_end));
249 do {
250 assert(bitmap->is_marked(obj_addr), "inv");
251 prefetch_obj(obj_addr);
252
253 oop obj = cast_to_oop(obj_addr);
254 const size_t obj_size = obj->size();
255 HeapWord* const obj_end_addr = obj_addr + obj_size;
256
257 {
258 // Process marked object.
259 assert(obj->is_self_forwarded(), "must be self-forwarded");
260 obj->unset_self_forwarded();
261 hr->update_bot_for_block(obj_addr, obj_end_addr);
262
263 // Statistics
264 num_marked_objs++;
265 marked_words += obj_size;
266 }
267
268 assert(obj_end_addr <= hr_top, "inv");
269 // Use hr_top as the limit so that we zap dead ranges up to the next
270 // marked obj or hr_top.
271 HeapWord* next_marked_obj_addr = bitmap->get_next_marked_addr(obj_end_addr, hr_top);
272 garbage_words += zap_dead_objects(hr, obj_end_addr, next_marked_obj_addr);
273 obj_addr = next_marked_obj_addr;
274 } while (obj_addr < chunk_end);
275
276 assert(marked_words > 0 && num_marked_objs > 0, "inv");
277
278 stat.register_objects_count_and_size(num_marked_objs, marked_words);
279
280 update_garbage_words_in_hr(hr, garbage_words);
281 }
282
283 public:
284 RestoreEvacFailureRegionsTask(G1EvacFailureRegions* evac_failure_regions) :
285 G1AbstractSubTask(G1GCPhaseTimes::RestoreEvacuationFailedRegions),
286 _g1h(G1CollectedHeap::heap()),
287 _cm(_g1h->concurrent_mark()),
288 _evac_failure_regions(evac_failure_regions),
289 _chunk_bitmap(mtGC) {
290
291 _num_evac_fail_regions = _evac_failure_regions->num_regions_evac_failed();
292 _num_chunks_per_region = G1CollectedHeap::get_chunks_per_region_for_scan();
293
294 _chunk_size = static_cast<uint>(G1HeapRegion::GrainWords / _num_chunks_per_region);
295
296 log_debug(gc, ergo)("Initializing removing self forwards with %u chunks per region",
297 _num_chunks_per_region);
298
299 _chunk_bitmap.resize(_num_chunks_per_region * _num_evac_fail_regions);
300 }
301
302 double worker_cost() const override {
303 assert(_evac_failure_regions->has_regions_evac_failed(), "Should not call this if there were no evacuation failures");
304
305 double workers_per_region = (double)G1CollectedHeap::get_chunks_per_region_for_scan() / G1RestoreRetainedRegionChunksPerWorker;
306 return workers_per_region * _evac_failure_regions->num_regions_evac_failed();
307 }
308
309 void do_work(uint worker_id) override {
310 const uint total_workers = G1CollectedHeap::heap()->workers()->active_workers();
311 const uint total_chunks = _num_chunks_per_region * _num_evac_fail_regions;
312 const uint start_chunk_idx = worker_id * total_chunks / total_workers;
313
314 for (uint i = 0; i < total_chunks; i++) {
315 const uint chunk_idx = (start_chunk_idx + i) % total_chunks;
316 if (claim_chunk(chunk_idx)) {
317 process_chunk(worker_id, chunk_idx);
318 }
319 }
320 }
321 };
322
323 G1PostEvacuateCollectionSetCleanupTask1::G1PostEvacuateCollectionSetCleanupTask1(G1ParScanThreadStateSet* per_thread_states,
324 G1EvacFailureRegions* evac_failure_regions) :
325 G1BatchedTask("Post Evacuate Cleanup 1", G1CollectedHeap::heap()->phase_times())
326 {
327 bool evac_failed = evac_failure_regions->has_regions_evac_failed();
328 bool alloc_failed = evac_failure_regions->has_regions_alloc_failed();
329
330 add_serial_task(new MergePssTask(per_thread_states));
331 add_serial_task(new RecalculateUsedTask(evac_failed, alloc_failed));
332 if (SampleCollectionSetCandidatesTask::should_execute()) {
333 add_serial_task(new SampleCollectionSetCandidatesTask());
334 }
335 add_parallel_task(G1CollectedHeap::heap()->rem_set()->create_cleanup_after_scan_heap_roots_task());
336 if (evac_failed) {
337 add_parallel_task(new RestoreEvacFailureRegionsTask(evac_failure_regions));
338 }
339 }
340
341 class G1FreeHumongousRegionClosure : public G1HeapRegionIndexClosure {
342 uint _humongous_objects_reclaimed;
343 uint _humongous_regions_reclaimed;
344 size_t _freed_bytes;
345 G1CollectedHeap* _g1h;
346
347 // Returns whether the given humongous object defined by the start region index
348 // is reclaimable.
349 //
350 // At this point in the garbage collection, checking whether the humongous object
351 // is still a candidate is sufficient because:
352 //
353 // - if it has not been a candidate at the start of collection, it will never
354 // changed to be a candidate during the gc (and live).
355 // - any found outstanding (i.e. in its remembered set, or from the collection
356 // set) references will set the candidate state to false.
357 // - there can be no references from within humongous starts regions referencing
358 // the object because we never allocate other objects into them.
359 // (I.e. there can be no intra-region references within humongous objects)
360 //
361 // It is not required to check whether the object has been found dead by marking
362 // or not, in fact it would prevent reclamation within a concurrent cycle, as
363 // all objects allocated during that time are considered live.
364 // SATB marking is even more conservative than the remembered set.
365 // So if at this point in the collection we did not find a reference during gc
366 // (or it had enough references to not be a candidate, having many remembered
367 // set entries), nobody has a reference to it.
368 //
369 // Since remembered sets are only ever updated by concurrent refinement threads
370 // at mutator time, the remembered sets do not need to be checked again.
371 //
372 // Other implementation considerations:
373 // - never consider non-typeArrays during marking as there is a considerable cost
374 // for maintaining the SATB invariant.
375 bool is_reclaimable(uint region_idx) const {
376 return G1CollectedHeap::heap()->is_humongous_reclaim_candidate(region_idx);
377 }
378
379 public:
380 G1FreeHumongousRegionClosure() :
381 _humongous_objects_reclaimed(0),
382 _humongous_regions_reclaimed(0),
383 _freed_bytes(0),
384 _g1h(G1CollectedHeap::heap())
385 {}
386
387 bool do_heap_region_index(uint region_index) override {
388 if (!is_reclaimable(region_index)) {
389 return false;
390 }
391
392 G1HeapRegion* r = _g1h->region_at(region_index);
393
394 oop obj = cast_to_oop(r->bottom());
395 {
396 ResourceMark rm;
397 bool mark_in_progress = _g1h->collector_state()->is_in_marking();
398 bool allocated_after_mark_start = false;
399 if (mark_in_progress) {
400 // top_at_mark_start() will assert if we are not in marking, so check first.
401 allocated_after_mark_start = r->bottom() == _g1h->concurrent_mark()->top_at_mark_start(r);
402 }
403
404 guarantee(_g1h->can_be_marked_through_immediately(obj) || (allocated_after_mark_start || !mark_in_progress),
405 "Only eagerly reclaiming arrays without oops is always supported, other humongous objects only if allocated after mark start, but the object "
406 PTR_FORMAT " (%s) is not (allocated after mark: %d mark in progress %d marked immediately %d is_array %d array_with_oops %d).",
407 p2i(r->bottom()), obj->klass()->name()->as_C_string(), allocated_after_mark_start, mark_in_progress, _g1h->can_be_marked_through_immediately(obj), obj->is_array(), obj->is_array_with_oops());
408 }
409 log_debug(gc, humongous)("Reclaimed humongous region %u (object size %zu @ " PTR_FORMAT ")",
410 region_index,
411 obj->size() * HeapWordSize,
412 p2i(r->bottom())
413 );
414
415 G1ConcurrentMark* const cm = _g1h->concurrent_mark();
416 cm->humongous_object_eagerly_reclaimed(r);
417 assert(!cm->is_marked_in_bitmap(obj),
418 "Eagerly reclaimed humongous region %u should not be marked at all but is in bitmap %s",
419 region_index,
420 BOOL_TO_STR(cm->is_marked_in_bitmap(obj)));
421 _humongous_objects_reclaimed++;
422
423 auto free_humongous_region = [&] (G1HeapRegion* r) {
424 _freed_bytes += r->used();
425 r->set_containing_set(nullptr);
426 _humongous_regions_reclaimed++;
427 G1HeapRegionPrinter::eager_reclaim(r);
428 // Humongous non-typeArrays may have dirty card tables. Need to be cleared. Do it
429 // for all types just in case.
430 r->clear_both_card_tables();
431 _g1h->free_humongous_region(r, nullptr);
432 };
433
434 _g1h->humongous_obj_regions_iterate(r, free_humongous_region);
435
436 return false;
437 }
438
439 uint humongous_objects_reclaimed() {
440 return _humongous_objects_reclaimed;
441 }
442
443 uint humongous_regions_reclaimed() {
444 return _humongous_regions_reclaimed;
445 }
446
447 size_t bytes_freed() const {
448 return _freed_bytes;
449 }
450 };
451
452 #ifdef COMPILER2
453 class G1PostEvacuateCollectionSetCleanupTask2::UpdateDerivedPointersTask : public G1AbstractSubTask {
454 public:
455 UpdateDerivedPointersTask() : G1AbstractSubTask(G1GCPhaseTimes::UpdateDerivedPointers) { }
456
457 double worker_cost() const override { return 1.0; }
458 void do_work(uint worker_id) override { DerivedPointerTable::update_pointers(); }
459 };
460 #endif // COMPILER2
461
462 class G1PostEvacuateCollectionSetCleanupTask2::EagerlyReclaimHumongousObjectsTask : public G1AbstractSubTask {
463 uint _humongous_regions_reclaimed;
464 size_t _bytes_freed;
465
466 public:
467 EagerlyReclaimHumongousObjectsTask() :
468 G1AbstractSubTask(G1GCPhaseTimes::EagerlyReclaimHumongousObjects),
469 _humongous_regions_reclaimed(0),
470 _bytes_freed(0) { }
471
472 virtual ~EagerlyReclaimHumongousObjectsTask() {
473 G1CollectedHeap* g1h = G1CollectedHeap::heap();
474
475 g1h->remove_from_old_gen_sets(0, _humongous_regions_reclaimed);
476 g1h->decrement_summary_bytes(_bytes_freed);
477 }
478
479 double worker_cost() const override { return 1.0; }
480 void do_work(uint worker_id) override {
481 G1CollectedHeap* g1h = G1CollectedHeap::heap();
482
483 G1FreeHumongousRegionClosure cl;
484 g1h->heap_region_iterate(&cl);
485
486 record_work_item(worker_id, G1GCPhaseTimes::EagerlyReclaimNumTotal, g1h->num_humongous_objects());
487 record_work_item(worker_id, G1GCPhaseTimes::EagerlyReclaimNumCandidates, g1h->num_humongous_reclaim_candidates());
488 record_work_item(worker_id, G1GCPhaseTimes::EagerlyReclaimNumReclaimed, cl.humongous_objects_reclaimed());
489
490 _humongous_regions_reclaimed = cl.humongous_regions_reclaimed();
491 _bytes_freed = cl.bytes_freed();
492 }
493 };
494
495 class G1PostEvacuateCollectionSetCleanupTask2::ProcessEvacuationFailedRegionsTask : public G1AbstractSubTask {
496 G1EvacFailureRegions* _evac_failure_regions;
497 G1HeapRegionClaimer _claimer;
498
499 class ProcessEvacuationFailedRegionsClosure : public G1HeapRegionClosure {
500 public:
501
502 bool do_heap_region(G1HeapRegion* r) override {
503 G1CollectedHeap* g1h = G1CollectedHeap::heap();
504 G1ConcurrentMark* cm = g1h->concurrent_mark();
505
506 // Retained regions are root regions for marking, so we must clear their mark data
507 // (tams, bitmap, ...). Outside of Concurrent Start GC we must always clear the mark data
508 // for the next GC.
509 bool clear_mark_data = !g1h->collector_state()->is_in_concurrent_start_gc() ||
510 g1h->policy()->should_retain_evac_failed_region(r);
511
512 if (clear_mark_data) {
513 g1h->clear_bitmap_for_region(r);
514 // Must be because this is a region that should not have been selected to
515 // be marked through.
516 cm->assert_top_at_mark_start_is_bottom(r);
517 } else {
518 // This evacuation failed region is going to be marked through. Update mark data.
519 // Since we have some marked live data information, pass that too.
520 cm->assert_statistics_clear(r);
521 cm->notify_new_region(r, r->live_bytes());
522 }
523 return false;
524 }
525 };
526
527 public:
528 ProcessEvacuationFailedRegionsTask(G1EvacFailureRegions* evac_failure_regions) :
529 G1AbstractSubTask(G1GCPhaseTimes::ProcessEvacuationFailedRegions),
530 _evac_failure_regions(evac_failure_regions),
531 _claimer(0) {
532 }
533
534 void set_max_workers(uint max_workers) override {
535 _claimer.set_n_workers(max_workers);
536 }
537
538 double worker_cost() const override {
539 return _evac_failure_regions->num_regions_evac_failed();
540 }
541
542 void do_work(uint worker_id) override {
543 ProcessEvacuationFailedRegionsClosure cl;
544 _evac_failure_regions->par_iterate(&cl, &_claimer, worker_id);
545 }
546 };
547
548 // Helper class to keep statistics for the collection set freeing
549 class FreeCSetStats {
550 size_t _before_used_bytes; // Usage in regions successfully evacuate
551 size_t _after_used_bytes; // Usage in regions failing evacuation
552 size_t _bytes_allocated_in_old_since_last_pause; // Size of young regions turned into old
553 size_t _failure_used_words; // Live size in failed regions
554 size_t _failure_waste_words; // Wasted size in failed regions
555 uint _regions_freed; // Number of regions freed
556
557 public:
558 FreeCSetStats() :
559 _before_used_bytes(0),
560 _after_used_bytes(0),
561 _bytes_allocated_in_old_since_last_pause(0),
562 _failure_used_words(0),
563 _failure_waste_words(0),
564 _regions_freed(0) { }
565
566 void merge_stats(FreeCSetStats* other) {
567 assert(other != nullptr, "invariant");
568 _before_used_bytes += other->_before_used_bytes;
569 _after_used_bytes += other->_after_used_bytes;
570 _bytes_allocated_in_old_since_last_pause += other->_bytes_allocated_in_old_since_last_pause;
571 _failure_used_words += other->_failure_used_words;
572 _failure_waste_words += other->_failure_waste_words;
573 _regions_freed += other->_regions_freed;
574 }
575
576 void report(G1CollectedHeap* g1h, G1EvacInfo* evacuation_info) {
577 evacuation_info->set_regions_freed(_regions_freed);
578 evacuation_info->set_collection_set_used_before(_before_used_bytes + _after_used_bytes);
579 evacuation_info->increment_collection_set_used_after(_after_used_bytes);
580
581 g1h->decrement_summary_bytes(_before_used_bytes);
582 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
583
584 G1Policy *policy = g1h->policy();
585 policy->old_gen_alloc_tracker()->add_allocated_non_humongous_bytes(_bytes_allocated_in_old_since_last_pause);
586
587 policy->cset_regions_freed();
588 }
589
590 void account_failed_region(G1HeapRegion* r) {
591 size_t used_words = r->live_bytes() / HeapWordSize;
592 _failure_used_words += used_words;
593 _failure_waste_words += G1HeapRegion::GrainWords - used_words;
594 _after_used_bytes += r->used();
595
596 // When moving a young gen region to old gen, we "allocate" that whole
597 // region there. This is in addition to any already evacuated objects.
598 // Notify the policy about that. Old gen regions do not cause an
599 // additional allocation: both the objects still in the region and the
600 // ones already moved are accounted for elsewhere.
601 if (r->is_young()) {
602 _bytes_allocated_in_old_since_last_pause += G1HeapRegion::GrainBytes;
603 }
604 }
605
606 void account_evacuated_region(G1HeapRegion* r) {
607 size_t used = r->used();
608 assert(used > 0, "region %u %s zero used", r->hrm_index(), r->get_short_type_str());
609 _before_used_bytes += used;
610 _regions_freed += 1;
611 }
612 };
613
614 // Closure applied to all regions in the collection set.
615 class FreeCSetClosure : public G1HeapRegionClosure {
616 // Helper to send JFR events for regions.
617 class JFREventForRegion {
618 EventGCPhaseParallel _event;
619
620 public:
621 JFREventForRegion(G1HeapRegion* region, uint worker_id) : _event() {
622 _event.set_gcId(GCId::current());
623 _event.set_gcWorkerId(worker_id);
624 if (region->is_young()) {
625 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
626 } else {
627 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
628 }
629 }
630
631 ~JFREventForRegion() {
632 _event.commit();
633 }
634 };
635
636 // Helper to do timing for region work.
637 class TimerForRegion {
638 Tickspan& _time;
639 Ticks _start_time;
640 public:
641 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
642 ~TimerForRegion() {
643 _time += Ticks::now() - _start_time;
644 }
645 };
646
647 // FreeCSetClosure members
648 G1CollectedHeap* _g1h;
649 const size_t* _surviving_young_words;
650 uint _worker_id;
651 Tickspan _young_time;
652 Tickspan _non_young_time;
653 FreeCSetStats* _stats;
654 G1EvacFailureRegions* _evac_failure_regions;
655 uint _num_retained_regions;
656
657 void assert_tracks_surviving_words(G1HeapRegion* r) {
658 assert(r->young_index_in_cset() != 0 &&
659 (uint)r->young_index_in_cset() <= _g1h->collection_set()->num_young_regions(),
660 "Young index %u is wrong for region %u of type %s with %u young regions",
661 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->num_young_regions());
662 }
663
664 void handle_evacuated_region(G1HeapRegion* r) {
665 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
666 stats()->account_evacuated_region(r);
667
668 G1HeapRegionPrinter::evac_reclaim(r);
669 // Free the region and its remembered set.
670 _g1h->free_region(r, nullptr);
671 }
672
673 void handle_failed_region(G1HeapRegion* r) {
674 // Do some allocation statistics accounting. Regions that failed evacuation
675 // are always made old, so there is no need to update anything in the young
676 // gen statistics, but we need to update old gen statistics.
677 stats()->account_failed_region(r);
678
679 G1GCPhaseTimes* p = _g1h->phase_times();
680 assert(r->in_collection_set(), "Failed evacuation of region %u not in collection set", r->hrm_index());
681
682 p->record_or_add_thread_work_item(G1GCPhaseTimes::RestoreEvacuationFailedRegions,
683 _worker_id,
684 1,
685 G1GCPhaseTimes::RestoreEvacFailureRegionsEvacFailedNum);
686
687 bool retain_region = _g1h->policy()->should_retain_evac_failed_region(r);
688 // Update the region state due to the failed evacuation.
689 r->handle_evacuation_failure(retain_region);
690 assert(r->is_old(), "must already be relabelled as old");
691
692 if (retain_region) {
693 _g1h->retain_region(r);
694 _num_retained_regions++;
695 }
696 assert(retain_region == r->rem_set()->is_tracked(), "When retaining a region, remembered set should be kept.");
697
698 // Add region to old set, need to hold lock.
699 MutexLocker x(G1OldSets_lock, Mutex::_no_safepoint_check_flag);
700 _g1h->old_set_add(r);
701 }
702
703 Tickspan& timer_for_region(G1HeapRegion* r) {
704 return r->is_young() ? _young_time : _non_young_time;
705 }
706
707 FreeCSetStats* stats() {
708 return _stats;
709 }
710
711 public:
712 FreeCSetClosure(const size_t* surviving_young_words,
713 uint worker_id,
714 FreeCSetStats* stats,
715 G1EvacFailureRegions* evac_failure_regions) :
716 G1HeapRegionClosure(),
717 _g1h(G1CollectedHeap::heap()),
718 _surviving_young_words(surviving_young_words),
719 _worker_id(worker_id),
720 _young_time(),
721 _non_young_time(),
722 _stats(stats),
723 _evac_failure_regions(evac_failure_regions),
724 _num_retained_regions(0) { }
725
726 virtual bool do_heap_region(G1HeapRegion* r) {
727 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
728 JFREventForRegion event(r, _worker_id);
729 TimerForRegion timer(timer_for_region(r));
730
731 if (r->is_young()) {
732 assert_tracks_surviving_words(r);
733 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
734 }
735
736 if (_evac_failure_regions->contains(r->hrm_index())) {
737 handle_failed_region(r);
738 } else {
739 handle_evacuated_region(r);
740 }
741 assert(!_g1h->is_on_master_free_list(r), "sanity");
742
743 return false;
744 }
745
746 void report_timing() {
747 G1GCPhaseTimes* pt = _g1h->phase_times();
748 if (_young_time.value() > 0) {
749 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
750 }
751 if (_non_young_time.value() > 0) {
752 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
753 }
754 }
755
756 bool num_retained_regions() const { return _num_retained_regions; }
757 };
758
759 class G1PostEvacuateCollectionSetCleanupTask2::FreeCollectionSetTask : public G1AbstractSubTask {
760 G1CollectedHeap* _g1h;
761 G1EvacInfo* _evacuation_info;
762 FreeCSetStats* _worker_stats;
763 G1HeapRegionClaimer _claimer;
764 const size_t* _surviving_young_words;
765 uint _active_workers;
766 G1EvacFailureRegions* _evac_failure_regions;
767 Atomic<uint> _num_retained_regions;
768
769 FreeCSetStats* worker_stats(uint worker) {
770 return &_worker_stats[worker];
771 }
772
773 void report_statistics() {
774 // Merge the accounting
775 FreeCSetStats total_stats;
776 for (uint worker = 0; worker < _active_workers; worker++) {
777 total_stats.merge_stats(worker_stats(worker));
778 }
779 total_stats.report(_g1h, _evacuation_info);
780 }
781
782 public:
783 FreeCollectionSetTask(G1EvacInfo* evacuation_info,
784 const size_t* surviving_young_words,
785 G1EvacFailureRegions* evac_failure_regions) :
786 G1AbstractSubTask(G1GCPhaseTimes::FreeCollectionSet),
787 _g1h(G1CollectedHeap::heap()),
788 _evacuation_info(evacuation_info),
789 _worker_stats(nullptr),
790 _claimer(0),
791 _surviving_young_words(surviving_young_words),
792 _active_workers(0),
793 _evac_failure_regions(evac_failure_regions),
794 _num_retained_regions(0) {
795
796 _g1h->clear_eden();
797 }
798
799 virtual ~FreeCollectionSetTask() {
800 Ticks serial_time = Ticks::now();
801
802 bool has_new_retained_regions = _num_retained_regions.load_relaxed() != 0;
803 if (has_new_retained_regions) {
804 G1CollectionSetCandidates* candidates = _g1h->collection_set()->candidates();
805 candidates->sort_by_efficiency();
806 }
807
808 report_statistics();
809 for (uint worker = 0; worker < _active_workers; worker++) {
810 _worker_stats[worker].~FreeCSetStats();
811 }
812 FREE_C_HEAP_ARRAY(_worker_stats);
813
814 _g1h->clear_collection_set();
815
816 G1GCPhaseTimes* p = _g1h->phase_times();
817 p->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
818 }
819
820 double worker_cost() const override { return G1CollectedHeap::heap()->collection_set()->num_initial_regions(); }
821
822 void set_max_workers(uint max_workers) override {
823 _active_workers = max_workers;
824 _worker_stats = NEW_C_HEAP_ARRAY(FreeCSetStats, max_workers, mtGC);
825 ::new (_worker_stats) FreeCSetStats[_active_workers]{};
826 _claimer.set_n_workers(_active_workers);
827 }
828
829 void do_work(uint worker_id) override {
830 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id), _evac_failure_regions);
831 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
832 // Report per-region type timings.
833 cl.report_timing();
834
835 _num_retained_regions.add_then_fetch(cl.num_retained_regions(), memory_order_relaxed);
836 }
837 };
838
839 class G1PostEvacuateCollectionSetCleanupTask2::ResizeTLABsAndSwapCardTableTask : public G1AbstractSubTask {
840 G1JavaThreadsListClaimer _claimer;
841
842 // There is not much work per thread so the number of threads per worker is high.
843 static const uint ThreadsPerWorker = 250;
844
845 public:
846 ResizeTLABsAndSwapCardTableTask()
847 : G1AbstractSubTask(G1GCPhaseTimes::ResizeThreadLABs), _claimer(ThreadsPerWorker)
848 {
849 G1BarrierSet::g1_barrier_set()->swap_global_card_table();
850 }
851
852 void do_work(uint worker_id) override {
853
854 class ResizeAndSwapCardTableClosure : public ThreadClosure {
855 public:
856
857 void do_thread(Thread* thread) {
858 if (UseTLAB && ResizeTLAB) {
859 thread->tlab().resize();
860 }
861
862 G1BarrierSet::g1_barrier_set()->update_card_table_base(thread);
863 }
864 } resize_and_swap_cl;
865
866 _claimer.apply(&resize_and_swap_cl);
867 }
868
869 double worker_cost() const override {
870 return (double)_claimer.length() / ThreadsPerWorker;
871 }
872 };
873
874 class G1PostEvacuateCollectionSetCleanupTask2::ResetPartialArrayStateManagerTask
875 : public G1AbstractSubTask
876 {
877 public:
878 ResetPartialArrayStateManagerTask()
879 : G1AbstractSubTask(G1GCPhaseTimes::ResetPartialArrayStateManager)
880 {}
881
882 double worker_cost() const override {
883 return AlmostNoWork;
884 }
885
886 void do_work(uint worker_id) override {
887 // This must be in phase2 cleanup, after phase1 has destroyed all of the
888 // associated allocators.
889 G1CollectedHeap::heap()->partial_array_state_manager()->reset();
890 }
891 };
892
893 G1PostEvacuateCollectionSetCleanupTask2::G1PostEvacuateCollectionSetCleanupTask2(G1ParScanThreadStateSet* per_thread_states,
894 G1EvacInfo* evacuation_info,
895 G1EvacFailureRegions* evac_failure_regions) :
896 G1BatchedTask("Post Evacuate Cleanup 2", G1CollectedHeap::heap()->phase_times())
897 {
898 #ifdef COMPILER2
899 add_serial_task(new UpdateDerivedPointersTask());
900 #endif // COMPILER2
901 if (G1CollectedHeap::heap()->has_humongous_reclaim_candidates()) {
902 add_serial_task(new EagerlyReclaimHumongousObjectsTask());
903 }
904 add_serial_task(new ResetPartialArrayStateManagerTask());
905
906 if (evac_failure_regions->has_regions_evac_failed()) {
907 add_parallel_task(new ProcessEvacuationFailedRegionsTask(evac_failure_regions));
908 }
909
910 add_parallel_task(new ResizeTLABsAndSwapCardTableTask());
911 add_parallel_task(new FreeCollectionSetTask(evacuation_info,
912 per_thread_states->surviving_young_words(),
913 evac_failure_regions));
914 }