1 /*
2 * Copyright (c) 2021, 2023, 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 "compiler/oopMap.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.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/g1HeapRegionRemSet.inline.hpp"
39 #include "gc/g1/g1OopClosures.inline.hpp"
40 #include "gc/g1/g1ParScanThreadState.hpp"
41 #include "gc/g1/g1RemSet.hpp"
42 #include "gc/g1/g1YoungGCPostEvacuateTasks.hpp"
43 #include "gc/shared/bufferNode.hpp"
44 #include "gc/shared/preservedMarks.inline.hpp"
45 #include "jfr/jfrEvents.hpp"
46 #include "oops/access.inline.hpp"
47 #include "oops/compressedOops.inline.hpp"
48 #include "oops/oop.inline.hpp"
49 #include "runtime/prefetch.hpp"
50 #include "runtime/threads.hpp"
51 #include "runtime/threadSMR.hpp"
52 #include "utilities/bitMap.inline.hpp"
53 #include "utilities/ticks.hpp"
54
55 class G1PostEvacuateCollectionSetCleanupTask1::MergePssTask : public G1AbstractSubTask {
56 G1ParScanThreadStateSet* _per_thread_states;
57
58 public:
59 MergePssTask(G1ParScanThreadStateSet* per_thread_states) :
60 G1AbstractSubTask(G1GCPhaseTimes::MergePSS),
61 _per_thread_states(per_thread_states) { }
62
63 double worker_cost() const override { return 1.0; }
64
65 void do_work(uint worker_id) override { _per_thread_states->flush_stats(); }
66 };
67
68 class G1PostEvacuateCollectionSetCleanupTask1::RecalculateUsedTask : public G1AbstractSubTask {
69 bool _evacuation_failed;
70 bool _allocation_failed;
71
72 public:
73 RecalculateUsedTask(bool evacuation_failed, bool allocation_failed) :
74 G1AbstractSubTask(G1GCPhaseTimes::RecalculateUsed),
75 _evacuation_failed(evacuation_failed),
76 _allocation_failed(allocation_failed) { }
77
78 double worker_cost() const override {
79 // If there is no evacuation failure, the work to perform is minimal.
80 return _evacuation_failed ? 1.0 : AlmostNoWork;
81 }
82
83 void do_work(uint worker_id) override {
84 G1CollectedHeap::heap()->update_used_after_gc(_evacuation_failed);
85 if (_allocation_failed) {
86 // Reset the G1GCAllocationFailureALot counters and flags
87 G1CollectedHeap::heap()->allocation_failure_injector()->reset();
88 }
89 }
90 };
91
92 class G1PostEvacuateCollectionSetCleanupTask1::SampleCollectionSetCandidatesTask : public G1AbstractSubTask {
93 public:
94 SampleCollectionSetCandidatesTask() : G1AbstractSubTask(G1GCPhaseTimes::SampleCollectionSetCandidates) { }
95
96 static bool should_execute() {
97 return G1CollectedHeap::heap()->should_sample_collection_set_candidates();
98 }
99
100 double worker_cost() const override {
101 return should_execute() ? 1.0 : AlmostNoWork;
102 }
103
104 void do_work(uint worker_id) override {
105 G1CollectedHeap* g1h = G1CollectedHeap::heap();
106
107 G1MonotonicArenaMemoryStats _total;
108 G1CollectionSetCandidates* candidates = g1h->collection_set()->candidates();
109 for (HeapRegion* r : *candidates) {
110 _total.add(r->rem_set()->card_set_memory_stats());
111 }
112 g1h->set_collection_set_candidates_stats(_total);
113 }
114 };
115
116 class G1PostEvacuateCollectionSetCleanupTask1::RestoreEvacFailureRegionsTask : public G1AbstractSubTask {
117 G1CollectedHeap* _g1h;
118 G1ConcurrentMark* _cm;
119
120 G1EvacFailureRegions* _evac_failure_regions;
121 CHeapBitMap _chunk_bitmap;
122
123 uint _num_chunks_per_region;
124 uint _num_evac_fail_regions;
125 size_t _chunk_size;
126
127 class PhaseTimesStat {
128 static constexpr G1GCPhaseTimes::GCParPhases phase_name =
129 G1GCPhaseTimes::RemoveSelfForwards;
130
131 G1GCPhaseTimes* _phase_times;
132 uint _worker_id;
133 Ticks _start;
134
135 public:
136 PhaseTimesStat(G1GCPhaseTimes* phase_times, uint worker_id) :
137 _phase_times(phase_times),
138 _worker_id(worker_id),
139 _start(Ticks::now()) { }
140
141 ~PhaseTimesStat() {
142 _phase_times->record_or_add_time_secs(phase_name,
143 _worker_id,
144 (Ticks::now() - _start).seconds());
145 }
146
147 void register_empty_chunk() {
148 _phase_times->record_or_add_thread_work_item(phase_name,
149 _worker_id,
150 1,
151 G1GCPhaseTimes::RemoveSelfForwardEmptyChunksNum);
152 }
153
154 void register_nonempty_chunk() {
155 _phase_times->record_or_add_thread_work_item(phase_name,
156 _worker_id,
157 1,
158 G1GCPhaseTimes::RemoveSelfForwardChunksNum);
159 }
160
161 void register_objects_count_and_size(size_t num_marked_obj, size_t marked_words) {
162 _phase_times->record_or_add_thread_work_item(phase_name,
163 _worker_id,
164 num_marked_obj,
165 G1GCPhaseTimes::RemoveSelfForwardObjectsNum);
166
167 size_t marked_bytes = marked_words * HeapWordSize;
168 _phase_times->record_or_add_thread_work_item(phase_name,
169 _worker_id,
170 marked_bytes,
171 G1GCPhaseTimes::RemoveSelfForwardObjectsBytes);
172 }
173 };
174
175 // Fill the memory area from start to end with filler objects, and update the BOT
176 // accordingly. Since we clear and use the bitmap for marking objects that failed
177 // evacuation, there is no other work to be done there.
178 static size_t zap_dead_objects(HeapRegion* hr, HeapWord* start, HeapWord* end) {
179 assert(start <= end, "precondition");
180 if (start == end) {
181 return 0;
182 }
183
184 hr->fill_range_with_dead_objects(start, end);
185 return pointer_delta(end, start);
186 }
187
188 static void update_garbage_words_in_hr(HeapRegion* hr, size_t garbage_words) {
189 if (garbage_words != 0) {
190 hr->note_self_forward_chunk_done(garbage_words * HeapWordSize);
191 }
192 }
193
194 static void prefetch_obj(HeapWord* obj_addr) {
195 Prefetch::write(obj_addr, PrefetchScanIntervalInBytes);
196 }
197
198 bool claim_chunk(uint chunk_idx) {
199 return _chunk_bitmap.par_set_bit(chunk_idx);
200 }
201
202 void process_chunk(uint worker_id, uint chunk_idx) {
203 PhaseTimesStat stat(_g1h->phase_times(), worker_id);
204
205 G1CMBitMap* bitmap = _cm->mark_bitmap();
206 const uint region_idx = _evac_failure_regions->get_region_idx(chunk_idx / _num_chunks_per_region);
207 HeapRegion* hr = _g1h->region_at(region_idx);
208
209 HeapWord* hr_bottom = hr->bottom();
210 HeapWord* hr_top = hr->top();
211 HeapWord* chunk_start = hr_bottom + (chunk_idx % _num_chunks_per_region) * _chunk_size;
212
213 assert(chunk_start < hr->end(), "inv");
214 if (chunk_start >= hr_top) {
215 return;
216 }
217
218 HeapWord* chunk_end = MIN2(chunk_start + _chunk_size, hr_top);
219 HeapWord* first_marked_addr = bitmap->get_next_marked_addr(chunk_start, hr_top);
220
221 size_t garbage_words = 0;
222
223 if (chunk_start == hr_bottom) {
224 // This is the bottom-most chunk in this region; zap [bottom, first_marked_addr).
225 garbage_words += zap_dead_objects(hr, hr_bottom, first_marked_addr);
226 }
227
228 if (first_marked_addr >= chunk_end) {
229 stat.register_empty_chunk();
230 update_garbage_words_in_hr(hr, garbage_words);
231 return;
232 }
233
234 stat.register_nonempty_chunk();
235
236 size_t num_marked_objs = 0;
237 size_t marked_words = 0;
238
239 HeapWord* obj_addr = first_marked_addr;
240 assert(chunk_start <= obj_addr && obj_addr < chunk_end,
241 "object " PTR_FORMAT " must be within chunk [" PTR_FORMAT ", " PTR_FORMAT "[",
242 p2i(obj_addr), p2i(chunk_start), p2i(chunk_end));
243 do {
244 assert(bitmap->is_marked(obj_addr), "inv");
245 prefetch_obj(obj_addr);
246
247 oop obj = cast_to_oop(obj_addr);
248 const size_t obj_size = obj->size();
249 HeapWord* const obj_end_addr = obj_addr + obj_size;
250
251 {
252 // Process marked object.
253 assert(obj->is_forwarded() && obj->forwardee() == obj, "must be self-forwarded");
254 obj->init_mark();
255 hr->update_bot_for_block(obj_addr, obj_end_addr);
256
257 // Statistics
258 num_marked_objs++;
259 marked_words += obj_size;
260 }
261
262 assert(obj_end_addr <= hr_top, "inv");
263 // Use hr_top as the limit so that we zap dead ranges up to the next
264 // marked obj or hr_top.
265 HeapWord* next_marked_obj_addr = bitmap->get_next_marked_addr(obj_end_addr, hr_top);
266 garbage_words += zap_dead_objects(hr, obj_end_addr, next_marked_obj_addr);
267 obj_addr = next_marked_obj_addr;
268 } while (obj_addr < chunk_end);
269
270 assert(marked_words > 0 && num_marked_objs > 0, "inv");
271
272 stat.register_objects_count_and_size(num_marked_objs, marked_words);
273
274 update_garbage_words_in_hr(hr, garbage_words);
275 }
276
277 public:
278 RestoreEvacFailureRegionsTask(G1EvacFailureRegions* evac_failure_regions) :
279 G1AbstractSubTask(G1GCPhaseTimes::RestoreEvacuationFailedRegions),
280 _g1h(G1CollectedHeap::heap()),
281 _cm(_g1h->concurrent_mark()),
282 _evac_failure_regions(evac_failure_regions),
283 _chunk_bitmap(mtGC) {
284
285 _num_evac_fail_regions = _evac_failure_regions->num_regions_evac_failed();
286 _num_chunks_per_region = G1CollectedHeap::get_chunks_per_region();
287
288 _chunk_size = static_cast<uint>(HeapRegion::GrainWords / _num_chunks_per_region);
289
290 log_debug(gc, ergo)("Initializing removing self forwards with %u chunks per region",
291 _num_chunks_per_region);
292
293 _chunk_bitmap.resize(_num_chunks_per_region * _num_evac_fail_regions);
294 }
295
296 double worker_cost() const override {
297 assert(_evac_failure_regions->has_regions_evac_failed(), "Should not call this if there were no evacuation failures");
298
299 double workers_per_region = (double)G1CollectedHeap::get_chunks_per_region() / G1RestoreRetainedRegionChunksPerWorker;
300 return workers_per_region * _evac_failure_regions->num_regions_evac_failed();
301 }
302
303 void do_work(uint worker_id) override {
304 const uint total_workers = G1CollectedHeap::heap()->workers()->active_workers();
305 const uint total_chunks = _num_chunks_per_region * _num_evac_fail_regions;
306 const uint start_chunk_idx = worker_id * total_chunks / total_workers;
307
308 for (uint i = 0; i < total_chunks; i++) {
309 const uint chunk_idx = (start_chunk_idx + i) % total_chunks;
310 if (claim_chunk(chunk_idx)) {
311 process_chunk(worker_id, chunk_idx);
312 }
313 }
314 }
315 };
316
317 G1PostEvacuateCollectionSetCleanupTask1::G1PostEvacuateCollectionSetCleanupTask1(G1ParScanThreadStateSet* per_thread_states,
318 G1EvacFailureRegions* evac_failure_regions) :
319 G1BatchedTask("Post Evacuate Cleanup 1", G1CollectedHeap::heap()->phase_times())
320 {
321 bool evac_failed = evac_failure_regions->has_regions_evac_failed();
322 bool alloc_failed = evac_failure_regions->has_regions_alloc_failed();
323
324 add_serial_task(new MergePssTask(per_thread_states));
325 add_serial_task(new RecalculateUsedTask(evac_failed, alloc_failed));
326 if (SampleCollectionSetCandidatesTask::should_execute()) {
327 add_serial_task(new SampleCollectionSetCandidatesTask());
328 }
329 add_parallel_task(G1CollectedHeap::heap()->rem_set()->create_cleanup_after_scan_heap_roots_task());
330 if (evac_failed) {
331 add_parallel_task(new RestoreEvacFailureRegionsTask(evac_failure_regions));
332 }
333 }
334
335 class G1FreeHumongousRegionClosure : public HeapRegionIndexClosure {
336 uint _humongous_objects_reclaimed;
337 uint _humongous_regions_reclaimed;
338 size_t _freed_bytes;
339 G1CollectedHeap* _g1h;
340
341 // Returns whether the given humongous object defined by the start region index
342 // is reclaimable.
343 //
344 // At this point in the garbage collection, checking whether the humongous object
345 // is still a candidate is sufficient because:
346 //
347 // - if it has not been a candidate at the start of collection, it will never
348 // changed to be a candidate during the gc (and live).
349 // - any found outstanding (i.e. in the DCQ, or in its remembered set)
350 // references will set the candidate state to false.
351 // - there can be no references from within humongous starts regions referencing
352 // the object because we never allocate other objects into them.
353 // (I.e. there can be no intra-region references)
354 //
355 // It is not required to check whether the object has been found dead by marking
356 // or not, in fact it would prevent reclamation within a concurrent cycle, as
357 // all objects allocated during that time are considered live.
358 // SATB marking is even more conservative than the remembered set.
359 // So if at this point in the collection we did not find a reference during gc
360 // (or it had enough references to not be a candidate, having many remembered
361 // set entries), nobody has a reference to it.
362 // At the start of collection we flush all refinement logs, and remembered sets
363 // are completely up-to-date wrt to references to the humongous object.
364 //
365 // So there is no need to re-check remembered set size of the humongous region.
366 //
367 // Other implementation considerations:
368 // - never consider object arrays at this time because they would pose
369 // considerable effort for cleaning up the remembered sets. This is
370 // required because stale remembered sets might reference locations that
371 // are currently allocated into.
372 bool is_reclaimable(uint region_idx) const {
373 return G1CollectedHeap::heap()->is_humongous_reclaim_candidate(region_idx);
374 }
375
376 public:
377 G1FreeHumongousRegionClosure() :
378 _humongous_objects_reclaimed(0),
379 _humongous_regions_reclaimed(0),
380 _freed_bytes(0),
381 _g1h(G1CollectedHeap::heap())
382 {}
383
384 bool do_heap_region_index(uint region_index) override {
385 if (!is_reclaimable(region_index)) {
386 return false;
387 }
388
389 HeapRegion* r = _g1h->region_at(region_index);
390
391 oop obj = cast_to_oop(r->bottom());
392 guarantee(obj->is_typeArray(),
393 "Only eagerly reclaiming type arrays is supported, but the object "
394 PTR_FORMAT " is not.", p2i(r->bottom()));
395
396 log_debug(gc, humongous)("Reclaimed humongous region %u (object size " SIZE_FORMAT " @ " PTR_FORMAT ")",
397 region_index,
398 obj->size() * HeapWordSize,
399 p2i(r->bottom())
400 );
401
402 G1ConcurrentMark* const cm = _g1h->concurrent_mark();
403 cm->humongous_object_eagerly_reclaimed(r);
404 assert(!cm->is_marked_in_bitmap(obj),
405 "Eagerly reclaimed humongous region %u should not be marked at all but is in bitmap %s",
406 region_index,
407 BOOL_TO_STR(cm->is_marked_in_bitmap(obj)));
408 _humongous_objects_reclaimed++;
409
410 auto free_humongous_region = [&] (HeapRegion* r) {
411 _freed_bytes += r->used();
412 r->set_containing_set(nullptr);
413 _humongous_regions_reclaimed++;
414 _g1h->free_humongous_region(r, nullptr);
415 _g1h->hr_printer()->cleanup(r);
416 };
417
418 _g1h->humongous_obj_regions_iterate(r, free_humongous_region);
419
420 return false;
421 }
422
423 uint humongous_objects_reclaimed() {
424 return _humongous_objects_reclaimed;
425 }
426
427 uint humongous_regions_reclaimed() {
428 return _humongous_regions_reclaimed;
429 }
430
431 size_t bytes_freed() const {
432 return _freed_bytes;
433 }
434 };
435
436 #if COMPILER2_OR_JVMCI
437 class G1PostEvacuateCollectionSetCleanupTask2::UpdateDerivedPointersTask : public G1AbstractSubTask {
438 public:
439 UpdateDerivedPointersTask() : G1AbstractSubTask(G1GCPhaseTimes::UpdateDerivedPointers) { }
440
441 double worker_cost() const override { return 1.0; }
442 void do_work(uint worker_id) override { DerivedPointerTable::update_pointers(); }
443 };
444 #endif
445
446 class G1PostEvacuateCollectionSetCleanupTask2::EagerlyReclaimHumongousObjectsTask : public G1AbstractSubTask {
447 uint _humongous_regions_reclaimed;
448 size_t _bytes_freed;
449
450 public:
451 EagerlyReclaimHumongousObjectsTask() :
452 G1AbstractSubTask(G1GCPhaseTimes::EagerlyReclaimHumongousObjects),
453 _humongous_regions_reclaimed(0),
454 _bytes_freed(0) { }
455
456 virtual ~EagerlyReclaimHumongousObjectsTask() {
457 G1CollectedHeap* g1h = G1CollectedHeap::heap();
458
459 g1h->remove_from_old_gen_sets(0, _humongous_regions_reclaimed);
460 g1h->decrement_summary_bytes(_bytes_freed);
461 }
462
463 double worker_cost() const override { return 1.0; }
464 void do_work(uint worker_id) override {
465 G1CollectedHeap* g1h = G1CollectedHeap::heap();
466
467 G1FreeHumongousRegionClosure cl;
468 g1h->heap_region_iterate(&cl);
469
470 record_work_item(worker_id, G1GCPhaseTimes::EagerlyReclaimNumTotal, g1h->num_humongous_objects());
471 record_work_item(worker_id, G1GCPhaseTimes::EagerlyReclaimNumCandidates, g1h->num_humongous_reclaim_candidates());
472 record_work_item(worker_id, G1GCPhaseTimes::EagerlyReclaimNumReclaimed, cl.humongous_objects_reclaimed());
473
474 _humongous_regions_reclaimed = cl.humongous_regions_reclaimed();
475 _bytes_freed = cl.bytes_freed();
476 }
477 };
478
479 class G1PostEvacuateCollectionSetCleanupTask2::RestorePreservedMarksTask : public G1AbstractSubTask {
480 PreservedMarksSet* _preserved_marks;
481 WorkerTask* _task;
482
483 public:
484 RestorePreservedMarksTask(PreservedMarksSet* preserved_marks) :
485 G1AbstractSubTask(G1GCPhaseTimes::RestorePreservedMarks),
486 _preserved_marks(preserved_marks),
487 _task(preserved_marks->create_task()) { }
488
489 virtual ~RestorePreservedMarksTask() {
490 delete _task;
491 }
492
493 double worker_cost() const override {
494 return _preserved_marks->num();
495 }
496
497 void do_work(uint worker_id) override { _task->work(worker_id); }
498 };
499
500 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
501 size_t _num_dirtied;
502 G1CollectedHeap* _g1h;
503 G1CardTable* _g1_ct;
504 G1EvacFailureRegions* _evac_failure_regions;
505
506 HeapRegion* region_for_card(CardValue* card_ptr) const {
507 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
508 }
509
510 bool will_become_free(HeapRegion* hr) const {
511 // A region will be freed by during the FreeCollectionSet phase if the region is in the
512 // collection set and has not had an evacuation failure.
513 return _g1h->is_in_cset(hr) && !_evac_failure_regions->contains(hr->hrm_index());
514 }
515
516 public:
517 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h, G1EvacFailureRegions* evac_failure_regions) :
518 G1CardTableEntryClosure(),
519 _num_dirtied(0),
520 _g1h(g1h),
521 _g1_ct(g1h->card_table()),
522 _evac_failure_regions(evac_failure_regions) { }
523
524 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
525 HeapRegion* hr = region_for_card(card_ptr);
526
527 // Should only dirty cards in regions that won't be freed.
528 if (!will_become_free(hr)) {
529 *card_ptr = G1CardTable::dirty_card_val();
530 _num_dirtied++;
531 }
532 }
533
534 size_t num_dirtied() const { return _num_dirtied; }
535 };
536
537 class G1PostEvacuateCollectionSetCleanupTask2::ProcessEvacuationFailedRegionsTask : public G1AbstractSubTask {
538 G1EvacFailureRegions* _evac_failure_regions;
539 HeapRegionClaimer _claimer;
540
541 class ProcessEvacuationFailedRegionsClosure : public HeapRegionClosure {
542 public:
543
544 bool do_heap_region(HeapRegion* r) override {
545 G1CollectedHeap* g1h = G1CollectedHeap::heap();
546 G1ConcurrentMark* cm = g1h->concurrent_mark();
547
548 HeapWord* top_at_mark_start = cm->top_at_mark_start(r);
549 assert(top_at_mark_start == r->bottom(), "TAMS must not have been set for region %u", r->hrm_index());
550 assert(cm->live_bytes(r->hrm_index()) == 0, "Marking live bytes must not be set for region %u", r->hrm_index());
551
552 // Concurrent mark does not mark through regions that we retain (they are root
553 // regions wrt to marking), so we must clear their mark data (tams, bitmap, ...)
554 // set eagerly or during evacuation failure.
555 bool clear_mark_data = !g1h->collector_state()->in_concurrent_start_gc() ||
556 g1h->policy()->should_retain_evac_failed_region(r);
557
558 if (clear_mark_data) {
559 g1h->clear_bitmap_for_region(r);
560 } else {
561 // This evacuation failed region is going to be marked through. Update mark data.
562 cm->update_top_at_mark_start(r);
563 cm->set_live_bytes(r->hrm_index(), r->live_bytes());
564 assert(cm->mark_bitmap()->get_next_marked_addr(r->bottom(), cm->top_at_mark_start(r)) != cm->top_at_mark_start(r),
565 "Marks must be on bitmap for region %u", r->hrm_index());
566 }
567 return false;
568 }
569 };
570
571 public:
572 ProcessEvacuationFailedRegionsTask(G1EvacFailureRegions* evac_failure_regions) :
573 G1AbstractSubTask(G1GCPhaseTimes::ProcessEvacuationFailedRegions),
574 _evac_failure_regions(evac_failure_regions),
575 _claimer(0) {
576 }
577
578 void set_max_workers(uint max_workers) override {
579 _claimer.set_n_workers(max_workers);
580 }
581
582 double worker_cost() const override {
583 return _evac_failure_regions->num_regions_evac_failed();
584 }
585
586 void do_work(uint worker_id) override {
587 ProcessEvacuationFailedRegionsClosure cl;
588 _evac_failure_regions->par_iterate(&cl, &_claimer, worker_id);
589 }
590 };
591
592 class G1PostEvacuateCollectionSetCleanupTask2::RedirtyLoggedCardsTask : public G1AbstractSubTask {
593 BufferNodeList* _rdc_buffers;
594 uint _num_buffer_lists;
595 G1EvacFailureRegions* _evac_failure_regions;
596
597 public:
598 RedirtyLoggedCardsTask(G1EvacFailureRegions* evac_failure_regions, BufferNodeList* rdc_buffers, uint num_buffer_lists) :
599 G1AbstractSubTask(G1GCPhaseTimes::RedirtyCards),
600 _rdc_buffers(rdc_buffers),
601 _num_buffer_lists(num_buffer_lists),
602 _evac_failure_regions(evac_failure_regions) { }
603
604 double worker_cost() const override {
605 // Needs more investigation.
606 return G1CollectedHeap::heap()->workers()->active_workers();
607 }
608
609 void do_work(uint worker_id) override {
610 RedirtyLoggedCardTableEntryClosure cl(G1CollectedHeap::heap(), _evac_failure_regions);
611
612 uint start = worker_id;
613 for (uint i = 0; i < _num_buffer_lists; i++) {
614 uint index = (start + i) % _num_buffer_lists;
615
616 BufferNode* next = Atomic::load(&_rdc_buffers[index]._head);
617 BufferNode* tail = Atomic::load(&_rdc_buffers[index]._tail);
618
619 while (next != nullptr) {
620 BufferNode* node = next;
621 next = Atomic::cmpxchg(&_rdc_buffers[index]._head, node, (node != tail ) ? node->next() : nullptr);
622 if (next == node) {
623 cl.apply_to_buffer(node, worker_id);
624 next = (node != tail ) ? node->next() : nullptr;
625 } else {
626 break; // If there is contention, move to the next BufferNodeList
627 }
628 }
629 }
630 record_work_item(worker_id, 0, cl.num_dirtied());
631 }
632 };
633
634 // Helper class to keep statistics for the collection set freeing
635 class FreeCSetStats {
636 size_t _before_used_bytes; // Usage in regions successfully evacuate
637 size_t _after_used_bytes; // Usage in regions failing evacuation
638 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
639 size_t _failure_used_words; // Live size in failed regions
640 size_t _failure_waste_words; // Wasted size in failed regions
641 size_t _card_rs_length; // (Card Set) Remembered set size
642 uint _regions_freed; // Number of regions freed
643
644 public:
645 FreeCSetStats() :
646 _before_used_bytes(0),
647 _after_used_bytes(0),
648 _bytes_allocated_in_old_since_last_gc(0),
649 _failure_used_words(0),
650 _failure_waste_words(0),
651 _card_rs_length(0),
652 _regions_freed(0) { }
653
654 void merge_stats(FreeCSetStats* other) {
655 assert(other != nullptr, "invariant");
656 _before_used_bytes += other->_before_used_bytes;
657 _after_used_bytes += other->_after_used_bytes;
658 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
659 _failure_used_words += other->_failure_used_words;
660 _failure_waste_words += other->_failure_waste_words;
661 _card_rs_length += other->_card_rs_length;
662 _regions_freed += other->_regions_freed;
663 }
664
665 void report(G1CollectedHeap* g1h, G1EvacInfo* evacuation_info) {
666 evacuation_info->set_regions_freed(_regions_freed);
667 evacuation_info->set_collection_set_used_before(_before_used_bytes + _after_used_bytes);
668 evacuation_info->increment_collection_set_used_after(_after_used_bytes);
669
670 g1h->decrement_summary_bytes(_before_used_bytes);
671 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
672
673 G1Policy *policy = g1h->policy();
674 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
675 policy->record_card_rs_length(_card_rs_length);
676 policy->cset_regions_freed();
677 }
678
679 void account_failed_region(HeapRegion* r) {
680 size_t used_words = r->live_bytes() / HeapWordSize;
681 _failure_used_words += used_words;
682 _failure_waste_words += HeapRegion::GrainWords - used_words;
683 _after_used_bytes += r->used();
684
685 // When moving a young gen region to old gen, we "allocate" that whole
686 // region there. This is in addition to any already evacuated objects.
687 // Notify the policy about that. Old gen regions do not cause an
688 // additional allocation: both the objects still in the region and the
689 // ones already moved are accounted for elsewhere.
690 if (r->is_young()) {
691 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
692 }
693 }
694
695 void account_evacuated_region(HeapRegion* r) {
696 size_t used = r->used();
697 assert(used > 0, "region %u %s zero used", r->hrm_index(), r->get_short_type_str());
698 _before_used_bytes += used;
699 _regions_freed += 1;
700 }
701
702 void account_card_rs_length(HeapRegion* r) {
703 _card_rs_length += r->rem_set()->occupied();
704 }
705 };
706
707 // Closure applied to all regions in the collection set.
708 class FreeCSetClosure : public HeapRegionClosure {
709 // Helper to send JFR events for regions.
710 class JFREventForRegion {
711 EventGCPhaseParallel _event;
712
713 public:
714 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
715 _event.set_gcId(GCId::current());
716 _event.set_gcWorkerId(worker_id);
717 if (region->is_young()) {
718 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
719 } else {
720 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
721 }
722 }
723
724 ~JFREventForRegion() {
725 _event.commit();
726 }
727 };
728
729 // Helper to do timing for region work.
730 class TimerForRegion {
731 Tickspan& _time;
732 Ticks _start_time;
733 public:
734 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
735 ~TimerForRegion() {
736 _time += Ticks::now() - _start_time;
737 }
738 };
739
740 // FreeCSetClosure members
741 G1CollectedHeap* _g1h;
742 const size_t* _surviving_young_words;
743 uint _worker_id;
744 Tickspan _young_time;
745 Tickspan _non_young_time;
746 FreeCSetStats* _stats;
747 G1EvacFailureRegions* _evac_failure_regions;
748 uint _num_retained_regions;
749
750 void assert_tracks_surviving_words(HeapRegion* r) {
751 assert(r->young_index_in_cset() != 0 &&
752 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
753 "Young index %u is wrong for region %u of type %s with %u young regions",
754 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
755 }
756
757 void handle_evacuated_region(HeapRegion* r) {
758 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
759 stats()->account_evacuated_region(r);
760
761 // Free the region and its remembered set.
762 _g1h->free_region(r, nullptr);
763 _g1h->hr_printer()->cleanup(r);
764 }
765
766 void handle_failed_region(HeapRegion* r) {
767 // Do some allocation statistics accounting. Regions that failed evacuation
768 // are always made old, so there is no need to update anything in the young
769 // gen statistics, but we need to update old gen statistics.
770 stats()->account_failed_region(r);
771
772 G1GCPhaseTimes* p = _g1h->phase_times();
773 assert(r->in_collection_set(), "Failed evacuation of region %u not in collection set", r->hrm_index());
774
775 p->record_or_add_thread_work_item(G1GCPhaseTimes::RestoreEvacuationFailedRegions,
776 _worker_id,
777 1,
778 G1GCPhaseTimes::RestoreEvacFailureRegionsEvacFailedNum);
779
780 bool retain_region = _g1h->policy()->should_retain_evac_failed_region(r);
781 // Update the region state due to the failed evacuation.
782 r->handle_evacuation_failure(retain_region);
783 assert(r->is_old(), "must already be relabelled as old");
784
785 if (retain_region) {
786 _g1h->retain_region(r);
787 _num_retained_regions++;
788 }
789 assert(retain_region == r->rem_set()->is_tracked(), "When retaining a region, remembered set should be kept.");
790
791 // Add region to old set, need to hold lock.
792 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
793 _g1h->old_set_add(r);
794 }
795
796 Tickspan& timer_for_region(HeapRegion* r) {
797 return r->is_young() ? _young_time : _non_young_time;
798 }
799
800 FreeCSetStats* stats() {
801 return _stats;
802 }
803
804 public:
805 FreeCSetClosure(const size_t* surviving_young_words,
806 uint worker_id,
807 FreeCSetStats* stats,
808 G1EvacFailureRegions* evac_failure_regions) :
809 HeapRegionClosure(),
810 _g1h(G1CollectedHeap::heap()),
811 _surviving_young_words(surviving_young_words),
812 _worker_id(worker_id),
813 _young_time(),
814 _non_young_time(),
815 _stats(stats),
816 _evac_failure_regions(evac_failure_regions),
817 _num_retained_regions(0) { }
818
819 virtual bool do_heap_region(HeapRegion* r) {
820 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
821 JFREventForRegion event(r, _worker_id);
822 TimerForRegion timer(timer_for_region(r));
823
824 stats()->account_card_rs_length(r);
825
826 if (r->is_young()) {
827 assert_tracks_surviving_words(r);
828 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
829 }
830
831 if (_evac_failure_regions->contains(r->hrm_index())) {
832 handle_failed_region(r);
833 } else {
834 handle_evacuated_region(r);
835 }
836 assert(!_g1h->is_on_master_free_list(r), "sanity");
837
838 return false;
839 }
840
841 void report_timing() {
842 G1GCPhaseTimes* pt = _g1h->phase_times();
843 if (_young_time.value() > 0) {
844 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
845 }
846 if (_non_young_time.value() > 0) {
847 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
848 }
849 }
850
851 bool num_retained_regions() const { return _num_retained_regions; }
852 };
853
854 class G1PostEvacuateCollectionSetCleanupTask2::FreeCollectionSetTask : public G1AbstractSubTask {
855 G1CollectedHeap* _g1h;
856 G1EvacInfo* _evacuation_info;
857 FreeCSetStats* _worker_stats;
858 HeapRegionClaimer _claimer;
859 const size_t* _surviving_young_words;
860 uint _active_workers;
861 G1EvacFailureRegions* _evac_failure_regions;
862 volatile uint _num_retained_regions;
863
864 FreeCSetStats* worker_stats(uint worker) {
865 return &_worker_stats[worker];
866 }
867
868 void report_statistics() {
869 // Merge the accounting
870 FreeCSetStats total_stats;
871 for (uint worker = 0; worker < _active_workers; worker++) {
872 total_stats.merge_stats(worker_stats(worker));
873 }
874 total_stats.report(_g1h, _evacuation_info);
875 }
876
877 public:
878 FreeCollectionSetTask(G1EvacInfo* evacuation_info,
879 const size_t* surviving_young_words,
880 G1EvacFailureRegions* evac_failure_regions) :
881 G1AbstractSubTask(G1GCPhaseTimes::FreeCollectionSet),
882 _g1h(G1CollectedHeap::heap()),
883 _evacuation_info(evacuation_info),
884 _worker_stats(nullptr),
885 _claimer(0),
886 _surviving_young_words(surviving_young_words),
887 _active_workers(0),
888 _evac_failure_regions(evac_failure_regions),
889 _num_retained_regions(0) {
890
891 _g1h->clear_eden();
892 }
893
894 virtual ~FreeCollectionSetTask() {
895 Ticks serial_time = Ticks::now();
896
897 bool has_new_retained_regions = Atomic::load(&_num_retained_regions) != 0;
898 if (has_new_retained_regions) {
899 G1CollectionSetCandidates* candidates = _g1h->collection_set()->candidates();
900 candidates->sort_by_efficiency();
901 }
902
903 report_statistics();
904 for (uint worker = 0; worker < _active_workers; worker++) {
905 _worker_stats[worker].~FreeCSetStats();
906 }
907 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
908
909 G1GCPhaseTimes* p = _g1h->phase_times();
910 p->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
911
912 _g1h->clear_collection_set();
913 }
914
915 double worker_cost() const override { return G1CollectedHeap::heap()->collection_set()->region_length(); }
916
917 void set_max_workers(uint max_workers) override {
918 _active_workers = max_workers;
919 _worker_stats = NEW_C_HEAP_ARRAY(FreeCSetStats, max_workers, mtGC);
920 for (uint worker = 0; worker < _active_workers; worker++) {
921 ::new (&_worker_stats[worker]) FreeCSetStats();
922 }
923 _claimer.set_n_workers(_active_workers);
924 }
925
926 void do_work(uint worker_id) override {
927 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id), _evac_failure_regions);
928 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
929 // Report per-region type timings.
930 cl.report_timing();
931
932 Atomic::add(&_num_retained_regions, cl.num_retained_regions(), memory_order_relaxed);
933 }
934 };
935
936 class G1PostEvacuateCollectionSetCleanupTask2::ResizeTLABsTask : public G1AbstractSubTask {
937 G1JavaThreadsListClaimer _claimer;
938
939 // There is not much work per thread so the number of threads per worker is high.
940 static const uint ThreadsPerWorker = 250;
941
942 public:
943 ResizeTLABsTask() : G1AbstractSubTask(G1GCPhaseTimes::ResizeThreadLABs), _claimer(ThreadsPerWorker) { }
944
945 void do_work(uint worker_id) override {
946 class ResizeClosure : public ThreadClosure {
947 public:
948
949 void do_thread(Thread* thread) {
950 static_cast<JavaThread*>(thread)->tlab().resize();
951 }
952 } cl;
953 _claimer.apply(&cl);
954 }
955
956 double worker_cost() const override {
957 return (double)_claimer.length() / ThreadsPerWorker;
958 }
959 };
960
961 G1PostEvacuateCollectionSetCleanupTask2::G1PostEvacuateCollectionSetCleanupTask2(G1ParScanThreadStateSet* per_thread_states,
962 G1EvacInfo* evacuation_info,
963 G1EvacFailureRegions* evac_failure_regions) :
964 G1BatchedTask("Post Evacuate Cleanup 2", G1CollectedHeap::heap()->phase_times())
965 {
966 #if COMPILER2_OR_JVMCI
967 add_serial_task(new UpdateDerivedPointersTask());
968 #endif
969 if (G1CollectedHeap::heap()->has_humongous_reclaim_candidates()) {
970 add_serial_task(new EagerlyReclaimHumongousObjectsTask());
971 }
972
973 if (evac_failure_regions->has_regions_evac_failed()) {
974 add_parallel_task(new RestorePreservedMarksTask(per_thread_states->preserved_marks_set()));
975 add_parallel_task(new ProcessEvacuationFailedRegionsTask(evac_failure_regions));
976 }
977 add_parallel_task(new RedirtyLoggedCardsTask(evac_failure_regions,
978 per_thread_states->rdc_buffers(),
979 per_thread_states->num_workers()));
980
981 if (UseTLAB && ResizeTLAB) {
982 add_parallel_task(new ResizeTLABsTask());
983 }
984 add_parallel_task(new FreeCollectionSetTask(evacuation_info,
985 per_thread_states->surviving_young_words(),
986 evac_failure_regions));
987 }