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/psCompactionManagerNew.hpp"
34 #include "gc/parallel/psParallelCompact.inline.hpp"
35 #include "gc/parallel/psPromotionManager.inline.hpp"
36 #include "gc/parallel/psRootType.hpp"
37 #include "gc/parallel/psScavenge.inline.hpp"
38 #include "gc/shared/gcCause.hpp"
39 #include "gc/shared/gcHeapSummary.hpp"
40 #include "gc/shared/gcId.hpp"
41 #include "gc/shared/gcLocker.hpp"
42 #include "gc/shared/gcTimer.hpp"
43 #include "gc/shared/gcTrace.hpp"
44 #include "gc/shared/gcTraceTime.inline.hpp"
45 #include "gc/shared/gcVMOperations.hpp"
46 #include "gc/shared/isGCActiveMark.hpp"
47 #include "gc/shared/oopStorage.inline.hpp"
48 #include "gc/shared/oopStorageSetParState.inline.hpp"
49 #include "gc/shared/oopStorageParState.inline.hpp"
50 #include "gc/shared/referencePolicy.hpp"
51 #include "gc/shared/referenceProcessor.hpp"
52 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
53 #include "gc/shared/scavengableNMethods.hpp"
54 #include "gc/shared/spaceDecorator.hpp"
55 #include "gc/shared/strongRootsScope.hpp"
56 #include "gc/shared/taskTerminator.hpp"
57 #include "gc/shared/weakProcessor.inline.hpp"
58 #include "gc/shared/workerPolicy.hpp"
59 #include "gc/shared/workerThread.hpp"
60 #include "gc/shared/workerUtils.hpp"
61 #include "memory/iterator.hpp"
62 #include "memory/resourceArea.hpp"
63 #include "memory/universe.hpp"
64 #include "logging/log.hpp"
65 #include "oops/access.inline.hpp"
66 #include "oops/compressedOops.inline.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/handles.inline.hpp"
69 #include "runtime/threadCritical.hpp"
70 #include "runtime/threads.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "runtime/vmOperations.hpp"
73 #include "services/memoryService.hpp"
74 #include "utilities/stack.inline.hpp"
75
76 SpanSubjectToDiscoveryClosure PSScavenge::_span_based_discoverer;
77 ReferenceProcessor* PSScavenge::_ref_processor = nullptr;
78 PSCardTable* PSScavenge::_card_table = nullptr;
79 bool PSScavenge::_survivor_overflow = false;
80 uint PSScavenge::_tenuring_threshold = 0;
81 HeapWord* PSScavenge::_young_generation_boundary = nullptr;
82 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
83 elapsedTimer PSScavenge::_accumulated_time;
84 STWGCTimer PSScavenge::_gc_timer;
85 ParallelScavengeTracer PSScavenge::_gc_tracer;
86 CollectorCounters* PSScavenge::_counters = nullptr;
87
88 static void scavenge_roots_work(ParallelRootType::Value root_type, uint worker_id) {
89 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
90
91 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
92 PSPromoteRootsClosure roots_to_old_closure(pm);
93
94 switch (root_type) {
95 case ParallelRootType::class_loader_data:
96 {
97 PSScavengeCLDClosure cld_closure(pm);
98 ClassLoaderDataGraph::cld_do(&cld_closure);
99 }
100 break;
101
102 case ParallelRootType::code_cache:
103 {
104 MarkingNMethodClosure code_closure(&roots_to_old_closure, NMethodToOopClosure::FixRelocations, false /* keepalive nmethods */);
105 ScavengableNMethods::nmethods_do(&code_closure);
106 }
107 break;
108
109 case ParallelRootType::sentinel:
110 DEBUG_ONLY(default:) // DEBUG_ONLY hack will create compile error on release builds (-Wswitch) and runtime check on debug builds
111 fatal("Bad enumeration value: %u", root_type);
112 break;
113 }
114
115 // Do the real work
116 pm->drain_stacks(false);
117 }
118
119 static void steal_work(TaskTerminator& terminator, uint worker_id) {
120 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
121
122 PSPromotionManager* pm =
123 PSPromotionManager::gc_thread_promotion_manager(worker_id);
124 pm->drain_stacks(true);
125 guarantee(pm->stacks_empty(),
126 "stacks should be empty at this point");
127
128 while (true) {
129 ScannerTask task;
130 if (PSPromotionManager::steal_depth(worker_id, task)) {
131 pm->process_popped_location_depth(task, true);
132 pm->drain_stacks_depth(true);
133 } else {
134 if (terminator.offer_termination()) {
135 break;
136 }
137 }
138 }
139 guarantee(pm->stacks_empty(), "stacks should be empty at this point");
140 }
141
142 // Define before use
143 class PSIsAliveClosure: public BoolObjectClosure {
144 public:
145 bool do_object_b(oop p) {
146 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
147 }
148 };
149
150 PSIsAliveClosure PSScavenge::_is_alive_closure;
151
152 class PSKeepAliveClosure: public OopClosure {
153 protected:
154 MutableSpace* _to_space;
155 PSPromotionManager* _promotion_manager;
156
157 public:
158 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
159 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
160 _to_space = heap->young_gen()->to_space();
161
162 assert(_promotion_manager != nullptr, "Sanity");
163 }
164
165 template <class T> void do_oop_work(T* p) {
166 #ifdef ASSERT
167 // Referent must be non-null and in from-space
168 oop obj = RawAccess<IS_NOT_NULL>::oop_load(p);
169 assert(oopDesc::is_oop(obj), "referent must be an oop");
170 assert(PSScavenge::is_obj_in_young(obj), "must be in young-gen");
171 assert(!PSScavenge::is_obj_in_to_space(obj), "must be in from-space");
172 #endif
173
174 _promotion_manager->copy_and_push_safe_barrier</*promote_immediately=*/false>(p);
175 }
176 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
177 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
178 };
179
180 class PSEvacuateFollowersClosure: public VoidClosure {
181 private:
182 PSPromotionManager* _promotion_manager;
183 TaskTerminator* _terminator;
184 uint _worker_id;
185
186 public:
187 PSEvacuateFollowersClosure(PSPromotionManager* pm, TaskTerminator* terminator, uint worker_id)
188 : _promotion_manager(pm), _terminator(terminator), _worker_id(worker_id) {}
189
190 virtual void do_void() {
191 assert(_promotion_manager != nullptr, "Sanity");
192 _promotion_manager->drain_stacks(true);
193 guarantee(_promotion_manager->stacks_empty(),
194 "stacks should be empty at this point");
195
196 if (_terminator != nullptr) {
197 steal_work(*_terminator, _worker_id);
198 }
199 }
200 };
201
202 class ParallelScavengeRefProcProxyTask : public RefProcProxyTask {
203 TaskTerminator _terminator;
204
205 public:
206 ParallelScavengeRefProcProxyTask(uint max_workers)
207 : RefProcProxyTask("ParallelScavengeRefProcProxyTask", max_workers),
208 _terminator(max_workers, UseCompactObjectHeaders ? ParCompactionManagerNew::marking_stacks() : ParCompactionManager::marking_stacks()) {}
209
210 void work(uint worker_id) override {
211 assert(worker_id < _max_workers, "sanity");
212 PSPromotionManager* promotion_manager = (_tm == RefProcThreadModel::Single) ? PSPromotionManager::vm_thread_promotion_manager() : PSPromotionManager::gc_thread_promotion_manager(worker_id);
213 PSIsAliveClosure is_alive;
214 PSKeepAliveClosure keep_alive(promotion_manager);
215 BarrierEnqueueDiscoveredFieldClosure enqueue;
216 PSEvacuateFollowersClosure complete_gc(promotion_manager, (_marks_oops_alive && _tm == RefProcThreadModel::Multi) ? &_terminator : nullptr, worker_id);;
217 _rp_task->rp_work(worker_id, &is_alive, &keep_alive, &enqueue, &complete_gc);
218 }
219
220 void prepare_run_task_hook() override {
221 _terminator.reset_for_reuse(_queue_count);
222 }
223 };
224
225 class PSThreadRootsTaskClosure : public ThreadClosure {
226 uint _worker_id;
227 public:
228 PSThreadRootsTaskClosure(uint worker_id) : _worker_id(worker_id) { }
229 virtual void do_thread(Thread* thread) {
230 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
231
232 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(_worker_id);
233 PSScavengeRootsClosure roots_closure(pm);
234 MarkingNMethodClosure roots_in_nmethods(&roots_closure, NMethodToOopClosure::FixRelocations, false /* keepalive nmethods */);
235
236 thread->oops_do(&roots_closure, &roots_in_nmethods);
237
238 // Do the real work
239 pm->drain_stacks(false);
240 }
241 };
242
243 class ScavengeRootsTask : public WorkerTask {
244 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
245 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_strong_par_state;
246 SequentialSubTasksDone _subtasks;
247 PSOldGen* _old_gen;
248 HeapWord* _gen_top;
249 uint _active_workers;
250 bool _is_old_gen_empty;
251 TaskTerminator _terminator;
252
253 public:
254 ScavengeRootsTask(PSOldGen* old_gen,
255 uint active_workers) :
256 WorkerTask("ScavengeRootsTask"),
257 _strong_roots_scope(active_workers),
258 _subtasks(ParallelRootType::sentinel),
259 _old_gen(old_gen),
260 _gen_top(old_gen->object_space()->top()),
261 _active_workers(active_workers),
262 _is_old_gen_empty(old_gen->object_space()->is_empty()),
263 _terminator(active_workers, PSPromotionManager::vm_thread_promotion_manager()->stack_array_depth()) {
264 if (!_is_old_gen_empty) {
265 PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table();
266 card_table->pre_scavenge(active_workers);
267 }
268 }
269
270 virtual void work(uint worker_id) {
271 assert(worker_id < _active_workers, "Sanity");
272 ResourceMark rm;
273
274 if (!_is_old_gen_empty) {
275 // There are only old-to-young pointers if there are objects
276 // in the old gen.
277 {
278 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
279 PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table();
280
281 // The top of the old gen changes during scavenge when objects are promoted.
282 card_table->scavenge_contents_parallel(_old_gen->start_array(),
283 _old_gen->object_space()->bottom(),
284 _gen_top,
285 pm,
286 worker_id,
287 _active_workers);
288
289 // Do the real work
290 pm->drain_stacks(false);
291 }
292 }
293
294 for (uint root_type = 0; _subtasks.try_claim_task(root_type); /* empty */ ) {
295 scavenge_roots_work(static_cast<ParallelRootType::Value>(root_type), worker_id);
296 }
297
298 PSThreadRootsTaskClosure closure(worker_id);
299 Threads::possibly_parallel_threads_do(true /* is_par */, &closure);
300
301 // Scavenge OopStorages
302 {
303 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
304 PSScavengeRootsClosure closure(pm);
305 _oop_storage_strong_par_state.oops_do(&closure);
306 // Do the real work
307 pm->drain_stacks(false);
308 }
309
310 // If active_workers can exceed 1, add a steal_work().
311 // PSPromotionManager::drain_stacks_depth() does not fully drain its
312 // stacks and expects a steal_work() to complete the draining if
313 // ParallelGCThreads is > 1.
314
315 if (_active_workers > 1) {
316 steal_work(_terminator, worker_id);
317 }
318 }
319 };
320
321 bool PSScavenge::invoke(bool clear_soft_refs) {
322 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
323 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
324
325 // Check for potential problems.
326 if (!should_attempt_scavenge()) {
327 return false;
328 }
329
330 IsSTWGCActiveMark mark;
331
332 _gc_timer.register_gc_start();
333
334 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
335 GCCause::Cause gc_cause = heap->gc_cause();
336
337 SvcGCMarker sgcm(SvcGCMarker::MINOR);
338 GCIdMark gc_id_mark;
339 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
340
341 bool promotion_failure_occurred = false;
342
343 PSYoungGen* young_gen = heap->young_gen();
344 PSOldGen* old_gen = heap->old_gen();
345 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
346
347 assert(young_gen->to_space()->is_empty(),
348 "Attempt to scavenge with live objects in to_space");
349
350 heap->increment_total_collections();
351
352 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
353 // Gather the feedback data for eden occupancy.
354 young_gen->eden_space()->accumulate_statistics();
355 }
356
357 heap->print_heap_before_gc();
358 heap->trace_heap_before_gc(&_gc_tracer);
359
360 assert(!NeverTenure || _tenuring_threshold == markWord::max_age + 1, "Sanity");
361 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
362
363 // Fill in TLABs
364 heap->ensure_parsability(true); // retire TLABs
365
366 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
367 Universe::verify("Before GC");
368 }
369
370 {
371 ResourceMark rm;
372
373 GCTraceCPUTime tcpu(&_gc_tracer);
374 GCTraceTime(Info, gc) tm("Pause Young", nullptr, gc_cause, true);
375 TraceCollectorStats tcs(counters());
376 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause, "end of minor GC");
377
378 if (log_is_enabled(Debug, gc, heap, exit)) {
379 accumulated_time()->start();
380 }
381
382 // Let the size policy know we're starting
383 size_policy->minor_collection_begin();
384
385 #if COMPILER2_OR_JVMCI
386 DerivedPointerTable::clear();
387 #endif
388
389 reference_processor()->start_discovery(clear_soft_refs);
390
391 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
392
393 // Reset our survivor overflow.
394 set_survivor_overflow(false);
395
396 const uint active_workers =
397 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().max_workers(),
398 ParallelScavengeHeap::heap()->workers().active_workers(),
399 Threads::number_of_non_daemon_threads());
400 ParallelScavengeHeap::heap()->workers().set_active_workers(active_workers);
401
402 PSPromotionManager::pre_scavenge();
403
404 {
405 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
406
407 ScavengeRootsTask task(old_gen, active_workers);
408 ParallelScavengeHeap::heap()->workers().run_task(&task);
409 }
410
411 // Process reference objects discovered during scavenge
412 {
413 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
414
415 reference_processor()->set_active_mt_degree(active_workers);
416 ReferenceProcessorStats stats;
417 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->max_num_queues());
418
419 ParallelScavengeRefProcProxyTask task(reference_processor()->max_num_queues());
420 stats = reference_processor()->process_discovered_references(task, pt);
421
422 _gc_tracer.report_gc_reference_stats(stats);
423 pt.print_all_references();
424 }
425
426 {
427 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
428 PSAdjustWeakRootsClosure root_closure;
429 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(), &_is_alive_closure, &root_closure, 1);
430 }
431
432 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
433 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
434 if (promotion_failure_occurred) {
435 clean_up_failed_promotion();
436 log_info(gc, promotion)("Promotion failed");
437 }
438
439 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
440
441 // Let the size policy know we're done. Note that we count promotion
442 // failure cleanup time as part of the collection (otherwise, we're
443 // implicitly saying it's mutator time).
444 size_policy->minor_collection_end(gc_cause);
445
446 if (!promotion_failure_occurred) {
447 // Swap the survivor spaces.
448 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
449 young_gen->from_space()->clear(SpaceDecorator::Mangle);
450 young_gen->swap_spaces();
451
452 size_t survived = young_gen->from_space()->used_in_bytes();
453 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used();
454 size_policy->update_averages(_survivor_overflow, survived, promoted);
455
456 // A successful scavenge should restart the GC time limit count which is
457 // for full GC's.
458 size_policy->reset_gc_overhead_limit_count();
459 if (UseAdaptiveSizePolicy) {
460 // Calculate the new survivor size and tenuring threshold
461
462 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
463 log_trace(gc, ergo)("old_gen_capacity: %zu young_gen_capacity: %zu",
464 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
465
466 if (UsePerfData) {
467 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
468 counters->update_old_eden_size(
469 size_policy->calculated_eden_size_in_bytes());
470 counters->update_old_promo_size(
471 size_policy->calculated_promo_size_in_bytes());
472 counters->update_old_capacity(old_gen->capacity_in_bytes());
473 counters->update_young_capacity(young_gen->capacity_in_bytes());
474 counters->update_survived(survived);
475 counters->update_promoted(promoted);
476 counters->update_survivor_overflowed(_survivor_overflow);
477 }
478
479 size_t max_young_size = young_gen->max_gen_size();
480
481 // Deciding a free ratio in the young generation is tricky, so if
482 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
483 // that the old generation size may have been limited because of them) we
484 // should then limit our young generation size using NewRatio to have it
485 // follow the old generation size.
486 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
487 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio,
488 young_gen->max_gen_size());
489 }
490
491 size_t survivor_limit =
492 size_policy->max_survivor_size(max_young_size);
493 _tenuring_threshold =
494 size_policy->compute_survivor_space_size_and_threshold(_survivor_overflow,
495 _tenuring_threshold,
496 survivor_limit);
497
498 log_debug(gc, age)("Desired survivor size %zu bytes, new threshold %u (max threshold %u)",
499 size_policy->calculated_survivor_size_in_bytes(),
500 _tenuring_threshold, MaxTenuringThreshold);
501
502 if (UsePerfData) {
503 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
504 counters->update_tenuring_threshold(_tenuring_threshold);
505 counters->update_survivor_size_counters();
506 }
507
508 // Do call at minor collections?
509 // Don't check if the size_policy is ready at this
510 // level. Let the size_policy check that internally.
511 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
512 AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
513 // Calculate optimal free space amounts
514 assert(young_gen->max_gen_size() >
515 young_gen->from_space()->capacity_in_bytes() +
516 young_gen->to_space()->capacity_in_bytes(),
517 "Sizes of space in young gen are out-of-bounds");
518
519 size_t young_live = young_gen->used_in_bytes();
520 size_t eden_live = young_gen->eden_space()->used_in_bytes();
521 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
522 size_t max_old_gen_size = old_gen->max_gen_size();
523 size_t max_eden_size = max_young_size -
524 young_gen->from_space()->capacity_in_bytes() -
525 young_gen->to_space()->capacity_in_bytes();
526
527 // Used for diagnostics
528 size_policy->clear_generation_free_space_flags();
529
530 size_policy->compute_eden_space_size(young_live,
531 eden_live,
532 cur_eden,
533 max_eden_size,
534 false /* not full gc*/);
535
536 size_policy->check_gc_overhead_limit(eden_live,
537 max_old_gen_size,
538 max_eden_size,
539 false /* not full gc*/,
540 gc_cause,
541 heap->soft_ref_policy());
542
543 size_policy->decay_supplemental_growth(false /* not full gc*/);
544 }
545 // Resize the young generation at every collection
546 // even if new sizes have not been calculated. This is
547 // to allow resizes that may have been inhibited by the
548 // relative location of the "to" and "from" spaces.
549
550 // Resizing the old gen at young collections can cause increases
551 // that don't feed back to the generation sizing policy until
552 // a full collection. Don't resize the old gen here.
553
554 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
555 size_policy->calculated_survivor_size_in_bytes());
556
557 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
558 }
559
560 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
561 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
562 // Also update() will case adaptive NUMA chunk resizing.
563 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
564 young_gen->eden_space()->update();
565
566 heap->gc_policy_counters()->update_counters();
567
568 heap->resize_all_tlabs();
569
570 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
571 }
572
573 #if COMPILER2_OR_JVMCI
574 DerivedPointerTable::update_pointers();
575 #endif
576
577 if (log_is_enabled(Debug, gc, heap, exit)) {
578 accumulated_time()->stop();
579 }
580
581 heap->print_heap_change(pre_gc_values);
582
583 // Track memory usage and detect low memory
584 MemoryService::track_memory_usage();
585 heap->update_counters();
586 }
587
588 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
589 Universe::verify("After GC");
590 }
591
592 heap->print_heap_after_gc();
593 heap->trace_heap_after_gc(&_gc_tracer);
594
595 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
596
597 _gc_timer.register_gc_end();
598
599 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
600
601 return !promotion_failure_occurred;
602 }
603
604 void PSScavenge::clean_up_failed_promotion() {
605 PSPromotionManager::restore_preserved_marks();
606
607 // Reset the PromotionFailureALot counters.
608 NOT_PRODUCT(ParallelScavengeHeap::heap()->reset_promotion_should_fail();)
609 }
610
611 bool PSScavenge::should_attempt_scavenge() {
612 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
613
614 PSYoungGen* young_gen = heap->young_gen();
615 PSOldGen* old_gen = heap->old_gen();
616
617 if (!young_gen->to_space()->is_empty()) {
618 // To-space is not empty; should run full-gc instead.
619 return false;
620 }
621
622 // Test to see if the scavenge will likely fail.
623 PSAdaptiveSizePolicy* policy = heap->size_policy();
624
625 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
626 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
627 // Total free size after possible old gen expansion
628 size_t free_in_old_gen = old_gen->max_gen_size() - old_gen->used_in_bytes();
629 bool result = promotion_estimate < free_in_old_gen;
630
631 log_trace(ergo)("%s scavenge: average_promoted %zu padded_average_promoted %zu free in old gen %zu",
632 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(),
633 (size_t) policy->padded_average_promoted_in_bytes(),
634 free_in_old_gen);
635
636 return result;
637 }
638
639 // Adaptive size policy support.
640 void PSScavenge::set_young_generation_boundary(HeapWord* v) {
641 _young_generation_boundary = v;
642 if (UseCompressedOops) {
643 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode(cast_to_oop(v));
644 }
645 }
646
647 void PSScavenge::initialize() {
648 // Arguments must have been parsed
649
650 if (AlwaysTenure || NeverTenure) {
651 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markWord::max_age + 1,
652 "MaxTenuringThreshold should be 0 or markWord::max_age + 1, but is %d", (int) MaxTenuringThreshold);
653 _tenuring_threshold = MaxTenuringThreshold;
654 } else {
655 // We want to smooth out our startup times for the AdaptiveSizePolicy
656 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
657 MaxTenuringThreshold;
658 }
659
660 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
661 PSYoungGen* young_gen = heap->young_gen();
662 PSOldGen* old_gen = heap->old_gen();
663
664 // Set boundary between young_gen and old_gen
665 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
666 "old above young");
667 set_young_generation_boundary(young_gen->eden_space()->bottom());
668
669 // Initialize ref handling object for scavenging.
670 _span_based_discoverer.set_span(young_gen->reserved());
671 _ref_processor =
672 new ReferenceProcessor(&_span_based_discoverer,
673 ParallelGCThreads, // mt processing degree
674 ParallelGCThreads, // mt discovery degree
675 false, // concurrent_discovery
676 &_is_alive_closure); // header provides liveness info
677
678 // Cache the cardtable
679 _card_table = heap->card_table();
680
681 _counters = new CollectorCounters("Parallel young collection pauses", 0);
682 }