1 /*
2 * Copyright (c) 2002, 2025, 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 "classfile/classLoaderDataGraph.hpp"
26 #include "classfile/stringTable.hpp"
27 #include "code/codeCache.hpp"
28 #include "compiler/oopMap.hpp"
29 #include "gc/parallel/parallelScavengeHeap.hpp"
30 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
31 #include "gc/parallel/psClosure.inline.hpp"
32 #include "gc/parallel/psCompactionManager.hpp"
33 #include "gc/parallel/psParallelCompact.inline.hpp"
34 #include "gc/parallel/psPromotionManager.inline.hpp"
35 #include "gc/parallel/psRootType.hpp"
36 #include "gc/parallel/psScavenge.inline.hpp"
37 #include "gc/shared/gcCause.hpp"
38 #include "gc/shared/gcHeapSummary.hpp"
39 #include "gc/shared/gcId.hpp"
40 #include "gc/shared/gcLocker.hpp"
41 #include "gc/shared/gcTimer.hpp"
42 #include "gc/shared/gcTrace.hpp"
43 #include "gc/shared/gcTraceTime.inline.hpp"
44 #include "gc/shared/gcVMOperations.hpp"
45 #include "gc/shared/isGCActiveMark.hpp"
46 #include "gc/shared/oopStorage.inline.hpp"
47 #include "gc/shared/oopStorageSetParState.inline.hpp"
48 #include "gc/shared/oopStorageParState.inline.hpp"
49 #include "gc/shared/referencePolicy.hpp"
50 #include "gc/shared/referenceProcessor.hpp"
51 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
52 #include "gc/shared/scavengableNMethods.hpp"
53 #include "gc/shared/spaceDecorator.hpp"
54 #include "gc/shared/strongRootsScope.hpp"
55 #include "gc/shared/taskTerminator.hpp"
56 #include "gc/shared/weakProcessor.inline.hpp"
57 #include "gc/shared/workerPolicy.hpp"
58 #include "gc/shared/workerThread.hpp"
59 #include "gc/shared/workerUtils.hpp"
60 #include "memory/iterator.hpp"
61 #include "memory/resourceArea.hpp"
62 #include "memory/universe.hpp"
63 #include "logging/log.hpp"
64 #include "oops/access.inline.hpp"
65 #include "oops/compressedOops.inline.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/handles.inline.hpp"
68 #include "runtime/threadCritical.hpp"
69 #include "runtime/threads.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "runtime/vmOperations.hpp"
72 #include "services/memoryService.hpp"
73 #include "utilities/stack.inline.hpp"
74
75 SpanSubjectToDiscoveryClosure PSScavenge::_span_based_discoverer;
76 ReferenceProcessor* PSScavenge::_ref_processor = nullptr;
77 PSCardTable* PSScavenge::_card_table = nullptr;
78 bool PSScavenge::_survivor_overflow = false;
79 uint PSScavenge::_tenuring_threshold = 0;
80 HeapWord* PSScavenge::_young_generation_boundary = nullptr;
81 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
82 elapsedTimer PSScavenge::_accumulated_time;
83 STWGCTimer PSScavenge::_gc_timer;
84 ParallelScavengeTracer PSScavenge::_gc_tracer;
85 CollectorCounters* PSScavenge::_counters = nullptr;
86
87 static void scavenge_roots_work(ParallelRootType::Value root_type, uint worker_id) {
88 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
89
90 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
91 PSPromoteRootsClosure roots_to_old_closure(pm);
92
93 switch (root_type) {
94 case ParallelRootType::class_loader_data:
95 {
96 PSScavengeCLDClosure cld_closure(pm);
97 ClassLoaderDataGraph::cld_do(&cld_closure);
98 }
99 break;
100
101 case ParallelRootType::code_cache:
102 {
103 MarkingNMethodClosure code_closure(&roots_to_old_closure, NMethodToOopClosure::FixRelocations, false /* keepalive nmethods */);
104 ScavengableNMethods::nmethods_do(&code_closure);
105 }
106 break;
107
108 case ParallelRootType::sentinel:
109 DEBUG_ONLY(default:) // DEBUG_ONLY hack will create compile error on release builds (-Wswitch) and runtime check on debug builds
110 fatal("Bad enumeration value: %u", root_type);
111 break;
112 }
113
114 // Do the real work
115 pm->drain_stacks(false);
116 }
117
118 static void steal_work(TaskTerminator& terminator, uint worker_id) {
119 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
120
121 PSPromotionManager* pm =
122 PSPromotionManager::gc_thread_promotion_manager(worker_id);
123 pm->drain_stacks(true);
124 guarantee(pm->stacks_empty(),
125 "stacks should be empty at this point");
126
127 while (true) {
128 ScannerTask task;
129 if (PSPromotionManager::steal_depth(worker_id, task)) {
130 pm->process_popped_location_depth(task, true);
131 pm->drain_stacks_depth(true);
132 } else {
133 if (terminator.offer_termination()) {
134 break;
135 }
136 }
137 }
138 guarantee(pm->stacks_empty(), "stacks should be empty at this point");
139 }
140
141 // Define before use
142 class PSIsAliveClosure: public BoolObjectClosure {
143 public:
144 bool do_object_b(oop p) {
145 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
146 }
147 };
148
149 PSIsAliveClosure PSScavenge::_is_alive_closure;
150
151 class PSKeepAliveClosure: public OopClosure {
152 protected:
153 MutableSpace* _to_space;
154 PSPromotionManager* _promotion_manager;
155
156 public:
157 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
158 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
159 _to_space = heap->young_gen()->to_space();
160
161 assert(_promotion_manager != nullptr, "Sanity");
162 }
163
164 template <class T> void do_oop_work(T* p) {
165 #ifdef ASSERT
166 // Referent must be non-null and in from-space
167 oop obj = RawAccess<IS_NOT_NULL>::oop_load(p);
168 assert(oopDesc::is_oop(obj), "referent must be an oop");
169 assert(PSScavenge::is_obj_in_young(obj), "must be in young-gen");
170 assert(!PSScavenge::is_obj_in_to_space(obj), "must be in from-space");
171 #endif
172
173 _promotion_manager->copy_and_push_safe_barrier</*promote_immediately=*/false>(p);
174 }
175 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
176 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
177 };
178
179 class PSEvacuateFollowersClosure: public VoidClosure {
180 private:
181 PSPromotionManager* _promotion_manager;
182 TaskTerminator* _terminator;
183 uint _worker_id;
184
185 public:
186 PSEvacuateFollowersClosure(PSPromotionManager* pm, TaskTerminator* terminator, uint worker_id)
187 : _promotion_manager(pm), _terminator(terminator), _worker_id(worker_id) {}
188
189 virtual void do_void() {
190 assert(_promotion_manager != nullptr, "Sanity");
191 _promotion_manager->drain_stacks(true);
192 guarantee(_promotion_manager->stacks_empty(),
193 "stacks should be empty at this point");
194
195 if (_terminator != nullptr) {
196 steal_work(*_terminator, _worker_id);
197 }
198 }
199 };
200
201 class ParallelScavengeRefProcProxyTask : public RefProcProxyTask {
202 TaskTerminator _terminator;
203
204 public:
205 ParallelScavengeRefProcProxyTask(uint max_workers)
206 : RefProcProxyTask("ParallelScavengeRefProcProxyTask", max_workers),
207 _terminator(max_workers, ParCompactionManager::marking_stacks()) {}
208
209 void work(uint worker_id) override {
210 assert(worker_id < _max_workers, "sanity");
211 PSPromotionManager* promotion_manager = (_tm == RefProcThreadModel::Single) ? PSPromotionManager::vm_thread_promotion_manager() : PSPromotionManager::gc_thread_promotion_manager(worker_id);
212 PSIsAliveClosure is_alive;
213 PSKeepAliveClosure keep_alive(promotion_manager);
214 BarrierEnqueueDiscoveredFieldClosure enqueue;
215 PSEvacuateFollowersClosure complete_gc(promotion_manager, (_marks_oops_alive && _tm == RefProcThreadModel::Multi) ? &_terminator : nullptr, worker_id);;
216 _rp_task->rp_work(worker_id, &is_alive, &keep_alive, &enqueue, &complete_gc);
217 }
218
219 void prepare_run_task_hook() override {
220 _terminator.reset_for_reuse(_queue_count);
221 }
222 };
223
224 class PSThreadRootsTaskClosure : public ThreadClosure {
225 uint _worker_id;
226 public:
227 PSThreadRootsTaskClosure(uint worker_id) : _worker_id(worker_id) { }
228 virtual void do_thread(Thread* thread) {
229 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
230
231 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(_worker_id);
232 PSScavengeRootsClosure roots_closure(pm);
233 MarkingNMethodClosure roots_in_nmethods(&roots_closure, NMethodToOopClosure::FixRelocations, false /* keepalive nmethods */);
234
235 thread->oops_do(&roots_closure, &roots_in_nmethods);
236
237 // Do the real work
238 pm->drain_stacks(false);
239 }
240 };
241
242 class ScavengeRootsTask : public WorkerTask {
243 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
244 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_strong_par_state;
245 SequentialSubTasksDone _subtasks;
246 PSOldGen* _old_gen;
247 HeapWord* _gen_top;
248 uint _active_workers;
249 bool _is_old_gen_empty;
250 TaskTerminator _terminator;
251
252 public:
253 ScavengeRootsTask(PSOldGen* old_gen,
254 uint active_workers) :
255 WorkerTask("ScavengeRootsTask"),
256 _strong_roots_scope(active_workers),
257 _subtasks(ParallelRootType::sentinel),
258 _old_gen(old_gen),
259 _gen_top(old_gen->object_space()->top()),
260 _active_workers(active_workers),
261 _is_old_gen_empty(old_gen->object_space()->is_empty()),
262 _terminator(active_workers, PSPromotionManager::vm_thread_promotion_manager()->stack_array_depth()) {
263 if (!_is_old_gen_empty) {
264 PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table();
265 card_table->pre_scavenge(active_workers);
266 }
267 }
268
269 virtual void work(uint worker_id) {
270 assert(worker_id < _active_workers, "Sanity");
271 ResourceMark rm;
272
273 if (!_is_old_gen_empty) {
274 // There are only old-to-young pointers if there are objects
275 // in the old gen.
276 {
277 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
278 PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table();
279
280 // The top of the old gen changes during scavenge when objects are promoted.
281 card_table->scavenge_contents_parallel(_old_gen->start_array(),
282 _old_gen->object_space()->bottom(),
283 _gen_top,
284 pm,
285 worker_id,
286 _active_workers);
287
288 // Do the real work
289 pm->drain_stacks(false);
290 }
291 }
292
293 for (uint root_type = 0; _subtasks.try_claim_task(root_type); /* empty */ ) {
294 scavenge_roots_work(static_cast<ParallelRootType::Value>(root_type), worker_id);
295 }
296
297 PSThreadRootsTaskClosure closure(worker_id);
298 Threads::possibly_parallel_threads_do(true /* is_par */, &closure);
299
300 // Scavenge OopStorages
301 {
302 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
303 PSScavengeRootsClosure closure(pm);
304 _oop_storage_strong_par_state.oops_do(&closure);
305 // Do the real work
306 pm->drain_stacks(false);
307 }
308
309 // If active_workers can exceed 1, add a steal_work().
310 // PSPromotionManager::drain_stacks_depth() does not fully drain its
311 // stacks and expects a steal_work() to complete the draining if
312 // ParallelGCThreads is > 1.
313
314 if (_active_workers > 1) {
315 steal_work(_terminator, worker_id);
316 }
317 }
318 };
319
320 bool PSScavenge::invoke(bool clear_soft_refs) {
321 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
322 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
323
324 // Check for potential problems.
325 if (!should_attempt_scavenge()) {
326 return false;
327 }
328
329 IsSTWGCActiveMark mark;
330
331 _gc_timer.register_gc_start();
332
333 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
334 GCCause::Cause gc_cause = heap->gc_cause();
335
336 SvcGCMarker sgcm(SvcGCMarker::MINOR);
337 GCIdMark gc_id_mark;
338 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
339
340 bool promotion_failure_occurred = false;
341
342 PSYoungGen* young_gen = heap->young_gen();
343 PSOldGen* old_gen = heap->old_gen();
344 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
345
346 assert(young_gen->to_space()->is_empty(),
347 "Attempt to scavenge with live objects in to_space");
348
349 heap->increment_total_collections();
350
351 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
352 // Gather the feedback data for eden occupancy.
353 young_gen->eden_space()->accumulate_statistics();
354 }
355
356 heap->print_heap_before_gc();
357 heap->trace_heap_before_gc(&_gc_tracer);
358
359 assert(!NeverTenure || _tenuring_threshold == markWord::max_age + 1, "Sanity");
360 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
361
362 // Fill in TLABs
363 heap->ensure_parsability(true); // retire TLABs
364
365 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
366 Universe::verify("Before GC");
367 }
368
369 {
370 ResourceMark rm;
371
372 GCTraceCPUTime tcpu(&_gc_tracer);
373 GCTraceTime(Info, gc) tm("Pause Young", nullptr, gc_cause, true);
374 TraceCollectorStats tcs(counters());
375 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause, "end of minor GC");
376
377 if (log_is_enabled(Debug, gc, heap, exit)) {
378 accumulated_time()->start();
379 }
380
381 // Let the size policy know we're starting
382 size_policy->minor_collection_begin();
383
384 #if COMPILER2_OR_JVMCI
385 DerivedPointerTable::clear();
386 #endif
387
388 reference_processor()->start_discovery(clear_soft_refs);
389
390 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
391
392 // Reset our survivor overflow.
393 set_survivor_overflow(false);
394
395 const uint active_workers =
396 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().max_workers(),
397 ParallelScavengeHeap::heap()->workers().active_workers(),
398 Threads::number_of_non_daemon_threads());
399 ParallelScavengeHeap::heap()->workers().set_active_workers(active_workers);
400
401 PSPromotionManager::pre_scavenge();
402
403 {
404 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
405
406 ScavengeRootsTask task(old_gen, active_workers);
407 ParallelScavengeHeap::heap()->workers().run_task(&task);
408 }
409
410 // Process reference objects discovered during scavenge
411 {
412 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
413
414 reference_processor()->set_active_mt_degree(active_workers);
415 ReferenceProcessorStats stats;
416 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->max_num_queues());
417
418 ParallelScavengeRefProcProxyTask task(reference_processor()->max_num_queues());
419 stats = reference_processor()->process_discovered_references(task, pt);
420
421 _gc_tracer.report_gc_reference_stats(stats);
422 pt.print_all_references();
423 }
424
425 {
426 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
427 PSAdjustWeakRootsClosure root_closure;
428 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(), &_is_alive_closure, &root_closure, 1);
429 }
430
431 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
432 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
433 if (promotion_failure_occurred) {
434 clean_up_failed_promotion();
435 log_info(gc, promotion)("Promotion failed");
436 }
437
438 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
439
440 // Let the size policy know we're done. Note that we count promotion
441 // failure cleanup time as part of the collection (otherwise, we're
442 // implicitly saying it's mutator time).
443 size_policy->minor_collection_end(gc_cause);
444
445 if (!promotion_failure_occurred) {
446 // Swap the survivor spaces.
447 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
448 young_gen->from_space()->clear(SpaceDecorator::Mangle);
449 young_gen->swap_spaces();
450
451 size_t survived = young_gen->from_space()->used_in_bytes();
452 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used();
453 size_policy->update_averages(_survivor_overflow, survived, promoted);
454
455 // A successful scavenge should restart the GC time limit count which is
456 // for full GC's.
457 size_policy->reset_gc_overhead_limit_count();
458 if (UseAdaptiveSizePolicy) {
459 // Calculate the new survivor size and tenuring threshold
460
461 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
462 log_trace(gc, ergo)("old_gen_capacity: %zu young_gen_capacity: %zu",
463 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
464
465 if (UsePerfData) {
466 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
467 counters->update_old_eden_size(
468 size_policy->calculated_eden_size_in_bytes());
469 counters->update_old_promo_size(
470 size_policy->calculated_promo_size_in_bytes());
471 counters->update_old_capacity(old_gen->capacity_in_bytes());
472 counters->update_young_capacity(young_gen->capacity_in_bytes());
473 counters->update_survived(survived);
474 counters->update_promoted(promoted);
475 counters->update_survivor_overflowed(_survivor_overflow);
476 }
477
478 size_t max_young_size = young_gen->max_gen_size();
479
480 // Deciding a free ratio in the young generation is tricky, so if
481 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
482 // that the old generation size may have been limited because of them) we
483 // should then limit our young generation size using NewRatio to have it
484 // follow the old generation size.
485 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
486 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio,
487 young_gen->max_gen_size());
488 }
489
490 size_t survivor_limit =
491 size_policy->max_survivor_size(max_young_size);
492 _tenuring_threshold =
493 size_policy->compute_survivor_space_size_and_threshold(_survivor_overflow,
494 _tenuring_threshold,
495 survivor_limit);
496
497 log_debug(gc, age)("Desired survivor size %zu bytes, new threshold %u (max threshold %u)",
498 size_policy->calculated_survivor_size_in_bytes(),
499 _tenuring_threshold, MaxTenuringThreshold);
500
501 if (UsePerfData) {
502 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
503 counters->update_tenuring_threshold(_tenuring_threshold);
504 counters->update_survivor_size_counters();
505 }
506
507 // Do call at minor collections?
508 // Don't check if the size_policy is ready at this
509 // level. Let the size_policy check that internally.
510 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
511 AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
512 // Calculate optimal free space amounts
513 assert(young_gen->max_gen_size() >
514 young_gen->from_space()->capacity_in_bytes() +
515 young_gen->to_space()->capacity_in_bytes(),
516 "Sizes of space in young gen are out-of-bounds");
517
518 size_t young_live = young_gen->used_in_bytes();
519 size_t eden_live = young_gen->eden_space()->used_in_bytes();
520 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
521 size_t max_old_gen_size = old_gen->max_gen_size();
522 size_t max_eden_size = max_young_size -
523 young_gen->from_space()->capacity_in_bytes() -
524 young_gen->to_space()->capacity_in_bytes();
525
526 // Used for diagnostics
527 size_policy->clear_generation_free_space_flags();
528
529 size_policy->compute_eden_space_size(young_live,
530 eden_live,
531 cur_eden,
532 max_eden_size,
533 false /* not full gc*/);
534
535 size_policy->check_gc_overhead_limit(eden_live,
536 max_old_gen_size,
537 max_eden_size,
538 false /* not full gc*/,
539 gc_cause,
540 heap->soft_ref_policy());
541
542 size_policy->decay_supplemental_growth(false /* not full gc*/);
543 }
544 // Resize the young generation at every collection
545 // even if new sizes have not been calculated. This is
546 // to allow resizes that may have been inhibited by the
547 // relative location of the "to" and "from" spaces.
548
549 // Resizing the old gen at young collections can cause increases
550 // that don't feed back to the generation sizing policy until
551 // a full collection. Don't resize the old gen here.
552
553 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
554 size_policy->calculated_survivor_size_in_bytes());
555
556 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
557 }
558
559 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
560 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
561 // Also update() will case adaptive NUMA chunk resizing.
562 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
563 young_gen->eden_space()->update();
564
565 heap->gc_policy_counters()->update_counters();
566
567 heap->resize_all_tlabs();
568
569 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
570 }
571
572 #if COMPILER2_OR_JVMCI
573 DerivedPointerTable::update_pointers();
574 #endif
575
576 if (log_is_enabled(Debug, gc, heap, exit)) {
577 accumulated_time()->stop();
578 }
579
580 heap->print_heap_change(pre_gc_values);
581
582 // Track memory usage and detect low memory
583 MemoryService::track_memory_usage();
584 heap->update_counters();
585 }
586
587 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
588 Universe::verify("After GC");
589 }
590
591 heap->print_heap_after_gc();
592 heap->trace_heap_after_gc(&_gc_tracer);
593
594 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
595
596 _gc_timer.register_gc_end();
597
598 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
599
600 return !promotion_failure_occurred;
601 }
602
603 void PSScavenge::clean_up_failed_promotion() {
604 PSPromotionManager::restore_preserved_marks();
605
606 // Reset the PromotionFailureALot counters.
607 NOT_PRODUCT(ParallelScavengeHeap::heap()->reset_promotion_should_fail();)
608 }
609
610 bool PSScavenge::should_attempt_scavenge() {
611 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
612
613 PSYoungGen* young_gen = heap->young_gen();
614 PSOldGen* old_gen = heap->old_gen();
615
616 if (!young_gen->to_space()->is_empty()) {
617 // To-space is not empty; should run full-gc instead.
618 return false;
619 }
620
621 // Test to see if the scavenge will likely fail.
622 PSAdaptiveSizePolicy* policy = heap->size_policy();
623
624 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
625 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
626 // Total free size after possible old gen expansion
627 size_t free_in_old_gen = old_gen->max_gen_size() - old_gen->used_in_bytes();
628 bool result = promotion_estimate < free_in_old_gen;
629
630 log_trace(ergo)("%s scavenge: average_promoted %zu padded_average_promoted %zu free in old gen %zu",
631 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(),
632 (size_t) policy->padded_average_promoted_in_bytes(),
633 free_in_old_gen);
634
635 return result;
636 }
637
638 // Adaptive size policy support.
639 void PSScavenge::set_young_generation_boundary(HeapWord* v) {
640 _young_generation_boundary = v;
641 if (UseCompressedOops) {
642 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode(cast_to_oop(v));
643 }
644 }
645
646 void PSScavenge::initialize() {
647 // Arguments must have been parsed
648
649 if (AlwaysTenure || NeverTenure) {
650 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markWord::max_age + 1,
651 "MaxTenuringThreshold should be 0 or markWord::max_age + 1, but is %d", (int) MaxTenuringThreshold);
652 _tenuring_threshold = MaxTenuringThreshold;
653 } else {
654 // We want to smooth out our startup times for the AdaptiveSizePolicy
655 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
656 MaxTenuringThreshold;
657 }
658
659 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
660 PSYoungGen* young_gen = heap->young_gen();
661 PSOldGen* old_gen = heap->old_gen();
662
663 // Set boundary between young_gen and old_gen
664 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
665 "old above young");
666 set_young_generation_boundary(young_gen->eden_space()->bottom());
667
668 // Initialize ref handling object for scavenging.
669 _span_based_discoverer.set_span(young_gen->reserved());
670 _ref_processor =
671 new ReferenceProcessor(&_span_based_discoverer,
672 ParallelGCThreads, // mt processing degree
673 ParallelGCThreads, // mt discovery degree
674 false, // concurrent_discovery
675 &_is_alive_closure); // header provides liveness info
676
677 // Cache the cardtable
678 _card_table = heap->card_table();
679
680 _counters = new CollectorCounters("Parallel young collection pauses", 0);
681 }