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/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 "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 (G1HeapRegion* 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(G1HeapRegion* 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(G1HeapRegion* 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 G1HeapRegion* 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->unset_self_forwarded();
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>(G1HeapRegion::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 G1HeapRegion* 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 = [&] (G1HeapRegion* r) {
411 _freed_bytes += r->used();
412 r->set_containing_set(nullptr);
413 _humongous_regions_reclaimed++;
414 G1HeapRegionPrinter::eager_reclaim(r);
415 _g1h->free_humongous_region(r, nullptr);
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 RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
480 size_t _num_dirtied;
481 G1CollectedHeap* _g1h;
482 G1CardTable* _g1_ct;
483 G1EvacFailureRegions* _evac_failure_regions;
484
485 G1HeapRegion* region_for_card(CardValue* card_ptr) const {
486 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
487 }
488
489 bool will_become_free(G1HeapRegion* hr) const {
490 // A region will be freed by during the FreeCollectionSet phase if the region is in the
491 // collection set and has not had an evacuation failure.
492 return _g1h->is_in_cset(hr) && !_evac_failure_regions->contains(hr->hrm_index());
493 }
494
495 public:
496 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h, G1EvacFailureRegions* evac_failure_regions) :
497 G1CardTableEntryClosure(),
498 _num_dirtied(0),
499 _g1h(g1h),
500 _g1_ct(g1h->card_table()),
501 _evac_failure_regions(evac_failure_regions) { }
502
503 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
504 G1HeapRegion* hr = region_for_card(card_ptr);
505
506 // Should only dirty cards in regions that won't be freed.
507 if (!will_become_free(hr)) {
508 *card_ptr = G1CardTable::dirty_card_val();
509 _num_dirtied++;
510 }
511 }
512
513 size_t num_dirtied() const { return _num_dirtied; }
514 };
515
516 class G1PostEvacuateCollectionSetCleanupTask2::ProcessEvacuationFailedRegionsTask : public G1AbstractSubTask {
517 G1EvacFailureRegions* _evac_failure_regions;
518 HeapRegionClaimer _claimer;
519
520 class ProcessEvacuationFailedRegionsClosure : public HeapRegionClosure {
521 public:
522
523 bool do_heap_region(G1HeapRegion* r) override {
524 G1CollectedHeap* g1h = G1CollectedHeap::heap();
525 G1ConcurrentMark* cm = g1h->concurrent_mark();
526
527 HeapWord* top_at_mark_start = cm->top_at_mark_start(r);
528 assert(top_at_mark_start == r->bottom(), "TAMS must not have been set for region %u", r->hrm_index());
529 assert(cm->live_bytes(r->hrm_index()) == 0, "Marking live bytes must not be set for region %u", r->hrm_index());
530
531 // Concurrent mark does not mark through regions that we retain (they are root
532 // regions wrt to marking), so we must clear their mark data (tams, bitmap, ...)
533 // set eagerly or during evacuation failure.
534 bool clear_mark_data = !g1h->collector_state()->in_concurrent_start_gc() ||
535 g1h->policy()->should_retain_evac_failed_region(r);
536
537 if (clear_mark_data) {
538 g1h->clear_bitmap_for_region(r);
539 } else {
540 // This evacuation failed region is going to be marked through. Update mark data.
541 cm->update_top_at_mark_start(r);
542 cm->set_live_bytes(r->hrm_index(), r->live_bytes());
543 assert(cm->mark_bitmap()->get_next_marked_addr(r->bottom(), cm->top_at_mark_start(r)) != cm->top_at_mark_start(r),
544 "Marks must be on bitmap for region %u", r->hrm_index());
545 }
546 return false;
547 }
548 };
549
550 public:
551 ProcessEvacuationFailedRegionsTask(G1EvacFailureRegions* evac_failure_regions) :
552 G1AbstractSubTask(G1GCPhaseTimes::ProcessEvacuationFailedRegions),
553 _evac_failure_regions(evac_failure_regions),
554 _claimer(0) {
555 }
556
557 void set_max_workers(uint max_workers) override {
558 _claimer.set_n_workers(max_workers);
559 }
560
561 double worker_cost() const override {
562 return _evac_failure_regions->num_regions_evac_failed();
563 }
564
565 void do_work(uint worker_id) override {
566 ProcessEvacuationFailedRegionsClosure cl;
567 _evac_failure_regions->par_iterate(&cl, &_claimer, worker_id);
568 }
569 };
570
571 class G1PostEvacuateCollectionSetCleanupTask2::RedirtyLoggedCardsTask : public G1AbstractSubTask {
572 BufferNodeList* _rdc_buffers;
573 uint _num_buffer_lists;
574 G1EvacFailureRegions* _evac_failure_regions;
575
576 public:
577 RedirtyLoggedCardsTask(G1EvacFailureRegions* evac_failure_regions, BufferNodeList* rdc_buffers, uint num_buffer_lists) :
578 G1AbstractSubTask(G1GCPhaseTimes::RedirtyCards),
579 _rdc_buffers(rdc_buffers),
580 _num_buffer_lists(num_buffer_lists),
581 _evac_failure_regions(evac_failure_regions) { }
582
583 double worker_cost() const override {
584 // Needs more investigation.
585 return G1CollectedHeap::heap()->workers()->active_workers();
586 }
587
588 void do_work(uint worker_id) override {
589 RedirtyLoggedCardTableEntryClosure cl(G1CollectedHeap::heap(), _evac_failure_regions);
590
591 uint start = worker_id;
592 for (uint i = 0; i < _num_buffer_lists; i++) {
593 uint index = (start + i) % _num_buffer_lists;
594
595 BufferNode* next = Atomic::load(&_rdc_buffers[index]._head);
596 BufferNode* tail = Atomic::load(&_rdc_buffers[index]._tail);
597
598 while (next != nullptr) {
599 BufferNode* node = next;
600 next = Atomic::cmpxchg(&_rdc_buffers[index]._head, node, (node != tail ) ? node->next() : nullptr);
601 if (next == node) {
602 cl.apply_to_buffer(node, worker_id);
603 next = (node != tail ) ? node->next() : nullptr;
604 } else {
605 break; // If there is contention, move to the next BufferNodeList
606 }
607 }
608 }
609 record_work_item(worker_id, 0, cl.num_dirtied());
610 }
611 };
612
613 // Helper class to keep statistics for the collection set freeing
614 class FreeCSetStats {
615 size_t _before_used_bytes; // Usage in regions successfully evacuate
616 size_t _after_used_bytes; // Usage in regions failing evacuation
617 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
618 size_t _failure_used_words; // Live size in failed regions
619 size_t _failure_waste_words; // Wasted size in failed regions
620 size_t _card_rs_length; // (Card Set) Remembered set size
621 uint _regions_freed; // Number of regions freed
622
623 public:
624 FreeCSetStats() :
625 _before_used_bytes(0),
626 _after_used_bytes(0),
627 _bytes_allocated_in_old_since_last_gc(0),
628 _failure_used_words(0),
629 _failure_waste_words(0),
630 _card_rs_length(0),
631 _regions_freed(0) { }
632
633 void merge_stats(FreeCSetStats* other) {
634 assert(other != nullptr, "invariant");
635 _before_used_bytes += other->_before_used_bytes;
636 _after_used_bytes += other->_after_used_bytes;
637 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
638 _failure_used_words += other->_failure_used_words;
639 _failure_waste_words += other->_failure_waste_words;
640 _card_rs_length += other->_card_rs_length;
641 _regions_freed += other->_regions_freed;
642 }
643
644 void report(G1CollectedHeap* g1h, G1EvacInfo* evacuation_info) {
645 evacuation_info->set_regions_freed(_regions_freed);
646 evacuation_info->set_collection_set_used_before(_before_used_bytes + _after_used_bytes);
647 evacuation_info->increment_collection_set_used_after(_after_used_bytes);
648
649 g1h->decrement_summary_bytes(_before_used_bytes);
650 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
651
652 G1Policy *policy = g1h->policy();
653 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
654 policy->record_card_rs_length(_card_rs_length);
655 policy->cset_regions_freed();
656 }
657
658 void account_failed_region(G1HeapRegion* r) {
659 size_t used_words = r->live_bytes() / HeapWordSize;
660 _failure_used_words += used_words;
661 _failure_waste_words += G1HeapRegion::GrainWords - used_words;
662 _after_used_bytes += r->used();
663
664 // When moving a young gen region to old gen, we "allocate" that whole
665 // region there. This is in addition to any already evacuated objects.
666 // Notify the policy about that. Old gen regions do not cause an
667 // additional allocation: both the objects still in the region and the
668 // ones already moved are accounted for elsewhere.
669 if (r->is_young()) {
670 _bytes_allocated_in_old_since_last_gc += G1HeapRegion::GrainBytes;
671 }
672 }
673
674 void account_evacuated_region(G1HeapRegion* r) {
675 size_t used = r->used();
676 assert(used > 0, "region %u %s zero used", r->hrm_index(), r->get_short_type_str());
677 _before_used_bytes += used;
678 _regions_freed += 1;
679 }
680
681 void account_card_rs_length(G1HeapRegion* r) {
682 _card_rs_length += r->rem_set()->occupied();
683 }
684 };
685
686 // Closure applied to all regions in the collection set.
687 class FreeCSetClosure : public HeapRegionClosure {
688 // Helper to send JFR events for regions.
689 class JFREventForRegion {
690 EventGCPhaseParallel _event;
691
692 public:
693 JFREventForRegion(G1HeapRegion* region, uint worker_id) : _event() {
694 _event.set_gcId(GCId::current());
695 _event.set_gcWorkerId(worker_id);
696 if (region->is_young()) {
697 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
698 } else {
699 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
700 }
701 }
702
703 ~JFREventForRegion() {
704 _event.commit();
705 }
706 };
707
708 // Helper to do timing for region work.
709 class TimerForRegion {
710 Tickspan& _time;
711 Ticks _start_time;
712 public:
713 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
714 ~TimerForRegion() {
715 _time += Ticks::now() - _start_time;
716 }
717 };
718
719 // FreeCSetClosure members
720 G1CollectedHeap* _g1h;
721 const size_t* _surviving_young_words;
722 uint _worker_id;
723 Tickspan _young_time;
724 Tickspan _non_young_time;
725 FreeCSetStats* _stats;
726 G1EvacFailureRegions* _evac_failure_regions;
727 uint _num_retained_regions;
728
729 void assert_tracks_surviving_words(G1HeapRegion* r) {
730 assert(r->young_index_in_cset() != 0 &&
731 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
732 "Young index %u is wrong for region %u of type %s with %u young regions",
733 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
734 }
735
736 void handle_evacuated_region(G1HeapRegion* r) {
737 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
738 stats()->account_evacuated_region(r);
739
740 G1HeapRegionPrinter::evac_reclaim(r);
741 // Free the region and its remembered set.
742 _g1h->free_region(r, nullptr);
743 }
744
745 void handle_failed_region(G1HeapRegion* r) {
746 // Do some allocation statistics accounting. Regions that failed evacuation
747 // are always made old, so there is no need to update anything in the young
748 // gen statistics, but we need to update old gen statistics.
749 stats()->account_failed_region(r);
750
751 G1GCPhaseTimes* p = _g1h->phase_times();
752 assert(r->in_collection_set(), "Failed evacuation of region %u not in collection set", r->hrm_index());
753
754 p->record_or_add_thread_work_item(G1GCPhaseTimes::RestoreEvacuationFailedRegions,
755 _worker_id,
756 1,
757 G1GCPhaseTimes::RestoreEvacFailureRegionsEvacFailedNum);
758
759 bool retain_region = _g1h->policy()->should_retain_evac_failed_region(r);
760 // Update the region state due to the failed evacuation.
761 r->handle_evacuation_failure(retain_region);
762 assert(r->is_old(), "must already be relabelled as old");
763
764 if (retain_region) {
765 _g1h->retain_region(r);
766 _num_retained_regions++;
767 }
768 assert(retain_region == r->rem_set()->is_tracked(), "When retaining a region, remembered set should be kept.");
769
770 // Add region to old set, need to hold lock.
771 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
772 _g1h->old_set_add(r);
773 }
774
775 Tickspan& timer_for_region(G1HeapRegion* r) {
776 return r->is_young() ? _young_time : _non_young_time;
777 }
778
779 FreeCSetStats* stats() {
780 return _stats;
781 }
782
783 public:
784 FreeCSetClosure(const size_t* surviving_young_words,
785 uint worker_id,
786 FreeCSetStats* stats,
787 G1EvacFailureRegions* evac_failure_regions) :
788 HeapRegionClosure(),
789 _g1h(G1CollectedHeap::heap()),
790 _surviving_young_words(surviving_young_words),
791 _worker_id(worker_id),
792 _young_time(),
793 _non_young_time(),
794 _stats(stats),
795 _evac_failure_regions(evac_failure_regions),
796 _num_retained_regions(0) { }
797
798 virtual bool do_heap_region(G1HeapRegion* r) {
799 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
800 JFREventForRegion event(r, _worker_id);
801 TimerForRegion timer(timer_for_region(r));
802
803 stats()->account_card_rs_length(r);
804
805 if (r->is_young()) {
806 assert_tracks_surviving_words(r);
807 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
808 }
809
810 if (_evac_failure_regions->contains(r->hrm_index())) {
811 handle_failed_region(r);
812 } else {
813 handle_evacuated_region(r);
814 }
815 assert(!_g1h->is_on_master_free_list(r), "sanity");
816
817 return false;
818 }
819
820 void report_timing() {
821 G1GCPhaseTimes* pt = _g1h->phase_times();
822 if (_young_time.value() > 0) {
823 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
824 }
825 if (_non_young_time.value() > 0) {
826 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
827 }
828 }
829
830 bool num_retained_regions() const { return _num_retained_regions; }
831 };
832
833 class G1PostEvacuateCollectionSetCleanupTask2::FreeCollectionSetTask : public G1AbstractSubTask {
834 G1CollectedHeap* _g1h;
835 G1EvacInfo* _evacuation_info;
836 FreeCSetStats* _worker_stats;
837 HeapRegionClaimer _claimer;
838 const size_t* _surviving_young_words;
839 uint _active_workers;
840 G1EvacFailureRegions* _evac_failure_regions;
841 volatile uint _num_retained_regions;
842
843 FreeCSetStats* worker_stats(uint worker) {
844 return &_worker_stats[worker];
845 }
846
847 void report_statistics() {
848 // Merge the accounting
849 FreeCSetStats total_stats;
850 for (uint worker = 0; worker < _active_workers; worker++) {
851 total_stats.merge_stats(worker_stats(worker));
852 }
853 total_stats.report(_g1h, _evacuation_info);
854 }
855
856 public:
857 FreeCollectionSetTask(G1EvacInfo* evacuation_info,
858 const size_t* surviving_young_words,
859 G1EvacFailureRegions* evac_failure_regions) :
860 G1AbstractSubTask(G1GCPhaseTimes::FreeCollectionSet),
861 _g1h(G1CollectedHeap::heap()),
862 _evacuation_info(evacuation_info),
863 _worker_stats(nullptr),
864 _claimer(0),
865 _surviving_young_words(surviving_young_words),
866 _active_workers(0),
867 _evac_failure_regions(evac_failure_regions),
868 _num_retained_regions(0) {
869
870 _g1h->clear_eden();
871 }
872
873 virtual ~FreeCollectionSetTask() {
874 Ticks serial_time = Ticks::now();
875
876 bool has_new_retained_regions = Atomic::load(&_num_retained_regions) != 0;
877 if (has_new_retained_regions) {
878 G1CollectionSetCandidates* candidates = _g1h->collection_set()->candidates();
879 candidates->sort_by_efficiency();
880 }
881
882 report_statistics();
883 for (uint worker = 0; worker < _active_workers; worker++) {
884 _worker_stats[worker].~FreeCSetStats();
885 }
886 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
887
888 G1GCPhaseTimes* p = _g1h->phase_times();
889 p->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
890
891 _g1h->clear_collection_set();
892 }
893
894 double worker_cost() const override { return G1CollectedHeap::heap()->collection_set()->region_length(); }
895
896 void set_max_workers(uint max_workers) override {
897 _active_workers = max_workers;
898 _worker_stats = NEW_C_HEAP_ARRAY(FreeCSetStats, max_workers, mtGC);
899 for (uint worker = 0; worker < _active_workers; worker++) {
900 ::new (&_worker_stats[worker]) FreeCSetStats();
901 }
902 _claimer.set_n_workers(_active_workers);
903 }
904
905 void do_work(uint worker_id) override {
906 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id), _evac_failure_regions);
907 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
908 // Report per-region type timings.
909 cl.report_timing();
910
911 Atomic::add(&_num_retained_regions, cl.num_retained_regions(), memory_order_relaxed);
912 }
913 };
914
915 class G1PostEvacuateCollectionSetCleanupTask2::ResizeTLABsTask : public G1AbstractSubTask {
916 G1JavaThreadsListClaimer _claimer;
917
918 // There is not much work per thread so the number of threads per worker is high.
919 static const uint ThreadsPerWorker = 250;
920
921 public:
922 ResizeTLABsTask() : G1AbstractSubTask(G1GCPhaseTimes::ResizeThreadLABs), _claimer(ThreadsPerWorker) { }
923
924 void do_work(uint worker_id) override {
925 class ResizeClosure : public ThreadClosure {
926 public:
927
928 void do_thread(Thread* thread) {
929 static_cast<JavaThread*>(thread)->tlab().resize();
930 }
931 } cl;
932 _claimer.apply(&cl);
933 }
934
935 double worker_cost() const override {
936 return (double)_claimer.length() / ThreadsPerWorker;
937 }
938 };
939
940 G1PostEvacuateCollectionSetCleanupTask2::G1PostEvacuateCollectionSetCleanupTask2(G1ParScanThreadStateSet* per_thread_states,
941 G1EvacInfo* evacuation_info,
942 G1EvacFailureRegions* evac_failure_regions) :
943 G1BatchedTask("Post Evacuate Cleanup 2", G1CollectedHeap::heap()->phase_times())
944 {
945 #if COMPILER2_OR_JVMCI
946 add_serial_task(new UpdateDerivedPointersTask());
947 #endif
948 if (G1CollectedHeap::heap()->has_humongous_reclaim_candidates()) {
949 add_serial_task(new EagerlyReclaimHumongousObjectsTask());
950 }
951
952 if (evac_failure_regions->has_regions_evac_failed()) {
953 add_parallel_task(new ProcessEvacuationFailedRegionsTask(evac_failure_regions));
954 }
955 add_parallel_task(new RedirtyLoggedCardsTask(evac_failure_regions,
956 per_thread_states->rdc_buffers(),
957 per_thread_states->num_workers()));
958
959 if (UseTLAB && ResizeTLAB) {
960 add_parallel_task(new ResizeTLABsTask());
961 }
962 add_parallel_task(new FreeCollectionSetTask(evacuation_info,
963 per_thread_states->surviving_young_words(),
964 evac_failure_regions));
965 }