1 /*
2 * Copyright (c) 2002, 2019, 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 #include "aot/aotLoader.hpp"
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "gc/parallel/parallelScavengeHeap.hpp"
31 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
32 #include "gc/parallel/psClosure.inline.hpp"
33 #include "gc/parallel/psCompactionManager.hpp"
34 #include "gc/parallel/psMarkSweepProxy.hpp"
35 #include "gc/parallel/psParallelCompact.inline.hpp"
36 #include "gc/parallel/psPromotionManager.inline.hpp"
37 #include "gc/parallel/psRootType.hpp"
38 #include "gc/parallel/psScavenge.inline.hpp"
39 #include "gc/shared/gcCause.hpp"
40 #include "gc/shared/gcHeapSummary.hpp"
41 #include "gc/shared/gcId.hpp"
42 #include "gc/shared/gcLocker.hpp"
43 #include "gc/shared/gcTimer.hpp"
44 #include "gc/shared/gcTrace.hpp"
45 #include "gc/shared/gcTraceTime.inline.hpp"
46 #include "gc/shared/isGCActiveMark.hpp"
47 #include "gc/shared/referencePolicy.hpp"
48 #include "gc/shared/referenceProcessor.hpp"
49 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
50 #include "gc/shared/scavengableNMethods.hpp"
51 #include "gc/shared/spaceDecorator.inline.hpp"
52 #include "gc/shared/weakProcessor.hpp"
53 #include "gc/shared/workerPolicy.hpp"
54 #include "gc/shared/workgroup.hpp"
55 #include "memory/resourceArea.hpp"
56 #include "memory/universe.hpp"
57 #include "logging/log.hpp"
58 #include "oops/access.inline.hpp"
59 #include "oops/compressedOops.inline.hpp"
60 #include "oops/oop.inline.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/handles.inline.hpp"
63 #include "runtime/threadCritical.hpp"
64 #include "runtime/vmThread.hpp"
65 #include "runtime/vmOperations.hpp"
66 #include "services/management.hpp"
67 #include "services/memoryService.hpp"
68 #include "utilities/stack.inline.hpp"
69
70 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
71 int PSScavenge::_consecutive_skipped_scavenges = 0;
72 SpanSubjectToDiscoveryClosure PSScavenge::_span_based_discoverer;
73 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
74 PSCardTable* PSScavenge::_card_table = NULL;
75 bool PSScavenge::_survivor_overflow = false;
76 uint PSScavenge::_tenuring_threshold = 0;
77 HeapWord* PSScavenge::_young_generation_boundary = NULL;
78 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
79 elapsedTimer PSScavenge::_accumulated_time;
80 STWGCTimer PSScavenge::_gc_timer;
81 ParallelScavengeTracer PSScavenge::_gc_tracer;
82 CollectorCounters* PSScavenge::_counters = NULL;
83
84 static void scavenge_roots_work(ParallelRootType::Value root_type, uint worker_id) {
85 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
86
87 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
88 PSScavengeRootsClosure roots_closure(pm);
89 PSPromoteRootsClosure roots_to_old_closure(pm);
90
91 switch (root_type) {
92 case ParallelRootType::universe:
93 Universe::oops_do(&roots_closure);
94 break;
95
96 case ParallelRootType::jni_handles:
97 JNIHandles::oops_do(&roots_closure);
98 break;
99
100 case ParallelRootType::object_synchronizer:
101 ObjectSynchronizer::oops_do(&roots_closure);
102 break;
103
104 case ParallelRootType::system_dictionary:
105 SystemDictionary::oops_do(&roots_closure);
106 break;
107
108 case ParallelRootType::class_loader_data:
109 {
110 PSScavengeCLDClosure cld_closure(pm);
111 ClassLoaderDataGraph::cld_do(&cld_closure);
112 }
113 break;
114
115 case ParallelRootType::management:
116 Management::oops_do(&roots_closure);
117 break;
118
119 case ParallelRootType::jvmti:
120 JvmtiExport::oops_do(&roots_closure);
121 break;
122
123 case ParallelRootType::code_cache:
124 {
125 MarkingCodeBlobClosure code_closure(&roots_to_old_closure, CodeBlobToOopClosure::FixRelocations);
126 ScavengableNMethods::nmethods_do(&code_closure);
127 AOTLoader::oops_do(&roots_closure);
128 }
129 break;
130
131 case ParallelRootType::sentinel:
132 DEBUG_ONLY(default:) // DEBUG_ONLY hack will create compile error on release builds (-Wswitch) and runtime check on debug builds
133 fatal("Bad enumeration value: %u", root_type);
134 break;
135 }
136
137 // Do the real work
138 pm->drain_stacks(false);
139 }
140
141 static void steal_work(ParallelTaskTerminator& terminator, uint worker_id) {
142 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
143
144 PSPromotionManager* pm =
145 PSPromotionManager::gc_thread_promotion_manager(worker_id);
146 pm->drain_stacks(true);
147 guarantee(pm->stacks_empty(),
148 "stacks should be empty at this point");
149
150 while (true) {
151 StarTask p;
152 if (PSPromotionManager::steal_depth(worker_id, p)) {
153 TASKQUEUE_STATS_ONLY(pm->record_steal(p));
154 pm->process_popped_location_depth(p);
155 pm->drain_stacks_depth(true);
156 } else {
157 if (terminator.offer_termination()) {
158 break;
159 }
160 }
161 }
162 guarantee(pm->stacks_empty(), "stacks should be empty at this point");
163 }
164
165 // Define before use
166 class PSIsAliveClosure: public BoolObjectClosure {
167 public:
168 bool do_object_b(oop p) {
169 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
170 }
171 };
172
173 PSIsAliveClosure PSScavenge::_is_alive_closure;
174
175 class PSKeepAliveClosure: public OopClosure {
176 protected:
177 MutableSpace* _to_space;
178 PSPromotionManager* _promotion_manager;
179
180 public:
181 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
182 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
183 _to_space = heap->young_gen()->to_space();
184
185 assert(_promotion_manager != NULL, "Sanity");
186 }
187
188 template <class T> void do_oop_work(T* p) {
189 assert (oopDesc::is_oop(RawAccess<IS_NOT_NULL>::oop_load(p)),
190 "expected an oop while scanning weak refs");
191
192 // Weak refs may be visited more than once.
193 if (PSScavenge::should_scavenge(p, _to_space)) {
194 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p);
195 }
196 }
197 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
198 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
199 };
200
201 class PSEvacuateFollowersClosure: public VoidClosure {
202 private:
203 PSPromotionManager* _promotion_manager;
204 public:
205 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
206
207 virtual void do_void() {
208 assert(_promotion_manager != NULL, "Sanity");
209 _promotion_manager->drain_stacks(true);
210 guarantee(_promotion_manager->stacks_empty(),
211 "stacks should be empty at this point");
212 }
213 };
214
215 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
216 virtual void execute(ProcessTask& process_task, uint ergo_workers);
217 };
218
219 class PSRefProcTask : public AbstractGangTask {
220 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
221 TaskTerminator _terminator;
222 ProcessTask& _task;
223 uint _active_workers;
224
225 public:
226 PSRefProcTask(ProcessTask& task, uint active_workers)
227 : AbstractGangTask("PSRefProcTask"),
228 _terminator(active_workers, PSPromotionManager::stack_array_depth()),
229 _task(task),
230 _active_workers(active_workers) {
231 }
232
233 virtual void work(uint worker_id) {
234 PSPromotionManager* promotion_manager =
235 PSPromotionManager::gc_thread_promotion_manager(worker_id);
236 assert(promotion_manager != NULL, "sanity check");
237 PSKeepAliveClosure keep_alive(promotion_manager);
238 PSEvacuateFollowersClosure evac_followers(promotion_manager);
239 PSIsAliveClosure is_alive;
240 _task.work(worker_id, is_alive, keep_alive, evac_followers);
241
242 if (_task.marks_oops_alive() && _active_workers > 1) {
243 steal_work(*_terminator.terminator(), worker_id);
244 }
245 }
246 };
247
248 void PSRefProcTaskExecutor::execute(ProcessTask& process_task, uint ergo_workers) {
249 PSRefProcTask task(process_task, ergo_workers);
250 ParallelScavengeHeap::heap()->workers().run_task(&task);
251 }
252
253 // This method contains all heap specific policy for invoking scavenge.
254 // PSScavenge::invoke_no_policy() will do nothing but attempt to
255 // scavenge. It will not clean up after failed promotions, bail out if
256 // we've exceeded policy time limits, or any other special behavior.
257 // All such policy should be placed here.
258 //
259 // Note that this method should only be called from the vm_thread while
260 // at a safepoint!
261 bool PSScavenge::invoke() {
262 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
263 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
264 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
265
266 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap();
267 PSAdaptiveSizePolicy* policy = heap->size_policy();
268 IsGCActiveMark mark;
269
270 const bool scavenge_done = PSScavenge::invoke_no_policy();
271 const bool need_full_gc = !scavenge_done ||
272 policy->should_full_GC(heap->old_gen()->free_in_bytes());
273 bool full_gc_done = false;
274
275 if (UsePerfData) {
276 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
277 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
278 counters->update_full_follows_scavenge(ffs_val);
279 }
280
281 if (need_full_gc) {
282 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
283 SoftRefPolicy* srp = heap->soft_ref_policy();
284 const bool clear_all_softrefs = srp->should_clear_all_soft_refs();
285
286 if (UseParallelOldGC) {
287 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
288 } else {
289 full_gc_done = PSMarkSweepProxy::invoke_no_policy(clear_all_softrefs);
290 }
291 }
292
293 return full_gc_done;
294 }
295
296 class PSThreadRootsTaskClosure : public ThreadClosure {
297 uint _worker_id;
298 public:
299 PSThreadRootsTaskClosure(uint worker_id) : _worker_id(worker_id) { }
300 virtual void do_thread(Thread* thread) {
301 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
302
303 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(_worker_id);
304 PSScavengeRootsClosure roots_closure(pm);
305 MarkingCodeBlobClosure roots_in_blobs(&roots_closure, CodeBlobToOopClosure::FixRelocations);
306
307 thread->oops_do(&roots_closure, &roots_in_blobs);
308
309 // Do the real work
310 pm->drain_stacks(false);
311 }
312 };
313
314 class ScavengeRootsTask : public AbstractGangTask {
315 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
316 SequentialSubTasksDone _subtasks;
317 PSOldGen* _old_gen;
318 HeapWord* _gen_top;
319 uint _active_workers;
320 bool _is_empty;
321 TaskTerminator _terminator;
322
323 public:
324 ScavengeRootsTask(PSOldGen* old_gen,
325 HeapWord* gen_top,
326 uint active_workers,
327 bool is_empty) :
328 AbstractGangTask("ScavengeRootsTask"),
329 _strong_roots_scope(active_workers),
330 _subtasks(),
331 _old_gen(old_gen),
332 _gen_top(gen_top),
333 _active_workers(active_workers),
334 _is_empty(is_empty),
335 _terminator(active_workers, PSPromotionManager::vm_thread_promotion_manager()->stack_array_depth()) {
336 _subtasks.set_n_threads(active_workers);
337 _subtasks.set_n_tasks(ParallelRootType::sentinel);
338 }
339
340 virtual void work(uint worker_id) {
341 ResourceMark rm;
342
343 if (!_is_empty) {
344 // There are only old-to-young pointers if there are objects
345 // in the old gen.
346
347 assert(_old_gen != NULL, "Sanity");
348 // There are no old-to-young pointers if the old gen is empty.
349 assert(!_old_gen->object_space()->is_empty(), "Should not be called is there is no work");
350 assert(_old_gen->object_space()->contains(_gen_top) || _gen_top == _old_gen->object_space()->top(), "Sanity");
351 assert(worker_id < ParallelGCThreads, "Sanity");
352
353 {
354 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
355 PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table();
356
357 card_table->scavenge_contents_parallel(_old_gen->start_array(),
358 _old_gen->object_space(),
359 _gen_top,
360 pm,
361 worker_id,
362 _active_workers);
363
364 // Do the real work
365 pm->drain_stacks(false);
366 }
367 }
368
369 for (uint root_type = 0; _subtasks.try_claim_task(root_type); /* empty */ ) {
370 scavenge_roots_work(static_cast<ParallelRootType::Value>(root_type), worker_id);
371 }
372 _subtasks.all_tasks_completed();
373
374 PSThreadRootsTaskClosure closure(worker_id);
375 Threads::possibly_parallel_threads_do(true /*parallel */, &closure);
376
377
378 // If active_workers can exceed 1, add a steal_work().
379 // PSPromotionManager::drain_stacks_depth() does not fully drain its
380 // stacks and expects a steal_work() to complete the draining if
381 // ParallelGCThreads is > 1.
382
383 if (_active_workers > 1) {
384 steal_work(*_terminator.terminator() , worker_id);
385 }
386 }
387 };
388
389 // This method contains no policy. You should probably
390 // be calling invoke() instead.
391 bool PSScavenge::invoke_no_policy() {
392 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
393 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
394
395 _gc_timer.register_gc_start();
396
397 TimeStamp scavenge_entry;
398 TimeStamp scavenge_midpoint;
399 TimeStamp scavenge_exit;
400
401 scavenge_entry.update();
402
403 if (GCLocker::check_active_before_gc()) {
404 return false;
405 }
406
407 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
408 GCCause::Cause gc_cause = heap->gc_cause();
409
410 // Check for potential problems.
411 if (!should_attempt_scavenge()) {
412 return false;
413 }
414
415 GCIdMark gc_id_mark;
416 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
417
418 bool promotion_failure_occurred = false;
419
420 PSYoungGen* young_gen = heap->young_gen();
421 PSOldGen* old_gen = heap->old_gen();
422 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
423
424 heap->increment_total_collections();
425
426 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
427 // Gather the feedback data for eden occupancy.
428 young_gen->eden_space()->accumulate_statistics();
429 }
430
431 heap->print_heap_before_gc();
432 heap->trace_heap_before_gc(&_gc_tracer);
433
434 assert(!NeverTenure || _tenuring_threshold == markWord::max_age + 1, "Sanity");
435 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
436
437 // Fill in TLABs
438 heap->ensure_parsability(true); // retire TLABs
439
440 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
441 HandleMark hm; // Discard invalid handles created during verification
442 Universe::verify("Before GC");
443 }
444
445 {
446 ResourceMark rm;
447 HandleMark hm;
448
449 GCTraceCPUTime tcpu;
450 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true);
451 TraceCollectorStats tcs(counters());
452 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause);
453
454 if (log_is_enabled(Debug, gc, heap, exit)) {
455 accumulated_time()->start();
456 }
457
458 // Let the size policy know we're starting
459 size_policy->minor_collection_begin();
460
461 // Verify the object start arrays.
462 if (VerifyObjectStartArray &&
463 VerifyBeforeGC) {
464 old_gen->verify_object_start_array();
465 }
466
467 // Verify no unmarked old->young roots
468 if (VerifyRememberedSets) {
469 heap->card_table()->verify_all_young_refs_imprecise();
470 }
471
472 assert(young_gen->to_space()->is_empty(),
473 "Attempt to scavenge with live objects in to_space");
474 young_gen->to_space()->clear(SpaceDecorator::Mangle);
475
476 save_to_space_top_before_gc();
477
478 #if COMPILER2_OR_JVMCI
479 DerivedPointerTable::clear();
480 #endif
481
482 reference_processor()->enable_discovery();
483 reference_processor()->setup_policy(false);
484
485 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
486
487 // Reset our survivor overflow.
488 set_survivor_overflow(false);
489
490 // We need to save the old top values before
491 // creating the promotion_manager. We pass the top
492 // values to the card_table, to prevent it from
493 // straying into the promotion labs.
494 HeapWord* old_top = old_gen->object_space()->top();
495
496 const uint active_workers =
497 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().total_workers(),
498 ParallelScavengeHeap::heap()->workers().active_workers(),
499 Threads::number_of_non_daemon_threads());
500 ParallelScavengeHeap::heap()->workers().update_active_workers(active_workers);
501
502 PSPromotionManager::pre_scavenge();
503
504 // We'll use the promotion manager again later.
505 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
506 {
507 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
508
509 ScavengeRootsTask task(old_gen, old_top, active_workers, old_gen->object_space()->is_empty());
510 ParallelScavengeHeap::heap()->workers().run_task(&task);
511 }
512
513 scavenge_midpoint.update();
514
515 // Process reference objects discovered during scavenge
516 {
517 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
518
519 reference_processor()->setup_policy(false); // not always_clear
520 reference_processor()->set_active_mt_degree(active_workers);
521 PSKeepAliveClosure keep_alive(promotion_manager);
522 PSEvacuateFollowersClosure evac_followers(promotion_manager);
523 ReferenceProcessorStats stats;
524 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->max_num_queues());
525 if (reference_processor()->processing_is_mt()) {
526 PSRefProcTaskExecutor task_executor;
527 stats = reference_processor()->process_discovered_references(
528 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
529 &pt);
530 } else {
531 stats = reference_processor()->process_discovered_references(
532 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt);
533 }
534
535 _gc_tracer.report_gc_reference_stats(stats);
536 pt.print_all_references();
537 }
538
539 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
540
541 PSScavengeRootsClosure root_closure(promotion_manager);
542
543 {
544 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
545 WeakProcessor::weak_oops_do(&_is_alive_closure, &root_closure);
546 }
547
548 // Verify that usage of root_closure didn't copy any objects.
549 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
550
551 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
552 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
553 if (promotion_failure_occurred) {
554 clean_up_failed_promotion();
555 log_info(gc, promotion)("Promotion failed");
556 }
557
558 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
559
560 // Let the size policy know we're done. Note that we count promotion
561 // failure cleanup time as part of the collection (otherwise, we're
562 // implicitly saying it's mutator time).
563 size_policy->minor_collection_end(gc_cause);
564
565 if (!promotion_failure_occurred) {
566 // Swap the survivor spaces.
567 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
568 young_gen->from_space()->clear(SpaceDecorator::Mangle);
569 young_gen->swap_spaces();
570
571 size_t survived = young_gen->from_space()->used_in_bytes();
572 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used();
573 size_policy->update_averages(_survivor_overflow, survived, promoted);
574
575 // A successful scavenge should restart the GC time limit count which is
576 // for full GC's.
577 size_policy->reset_gc_overhead_limit_count();
578 if (UseAdaptiveSizePolicy) {
579 // Calculate the new survivor size and tenuring threshold
580
581 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
582 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
583 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
584
585 if (UsePerfData) {
586 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
587 counters->update_old_eden_size(
588 size_policy->calculated_eden_size_in_bytes());
589 counters->update_old_promo_size(
590 size_policy->calculated_promo_size_in_bytes());
591 counters->update_old_capacity(old_gen->capacity_in_bytes());
592 counters->update_young_capacity(young_gen->capacity_in_bytes());
593 counters->update_survived(survived);
594 counters->update_promoted(promoted);
595 counters->update_survivor_overflowed(_survivor_overflow);
596 }
597
598 size_t max_young_size = young_gen->max_size();
599
600 // Deciding a free ratio in the young generation is tricky, so if
601 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
602 // that the old generation size may have been limited because of them) we
603 // should then limit our young generation size using NewRatio to have it
604 // follow the old generation size.
605 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
606 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
607 }
608
609 size_t survivor_limit =
610 size_policy->max_survivor_size(max_young_size);
611 _tenuring_threshold =
612 size_policy->compute_survivor_space_size_and_threshold(
613 _survivor_overflow,
614 _tenuring_threshold,
615 survivor_limit);
616
617 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")",
618 size_policy->calculated_survivor_size_in_bytes(),
619 _tenuring_threshold, MaxTenuringThreshold);
620
621 if (UsePerfData) {
622 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
623 counters->update_tenuring_threshold(_tenuring_threshold);
624 counters->update_survivor_size_counters();
625 }
626
627 // Do call at minor collections?
628 // Don't check if the size_policy is ready at this
629 // level. Let the size_policy check that internally.
630 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
631 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) {
632 // Calculate optimal free space amounts
633 assert(young_gen->max_size() >
634 young_gen->from_space()->capacity_in_bytes() +
635 young_gen->to_space()->capacity_in_bytes(),
636 "Sizes of space in young gen are out-of-bounds");
637
638 size_t young_live = young_gen->used_in_bytes();
639 size_t eden_live = young_gen->eden_space()->used_in_bytes();
640 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
641 size_t max_old_gen_size = old_gen->max_gen_size();
642 size_t max_eden_size = max_young_size -
643 young_gen->from_space()->capacity_in_bytes() -
644 young_gen->to_space()->capacity_in_bytes();
645
646 // Used for diagnostics
647 size_policy->clear_generation_free_space_flags();
648
649 size_policy->compute_eden_space_size(young_live,
650 eden_live,
651 cur_eden,
652 max_eden_size,
653 false /* not full gc*/);
654
655 size_policy->check_gc_overhead_limit(eden_live,
656 max_old_gen_size,
657 max_eden_size,
658 false /* not full gc*/,
659 gc_cause,
660 heap->soft_ref_policy());
661
662 size_policy->decay_supplemental_growth(false /* not full gc*/);
663 }
664 // Resize the young generation at every collection
665 // even if new sizes have not been calculated. This is
666 // to allow resizes that may have been inhibited by the
667 // relative location of the "to" and "from" spaces.
668
669 // Resizing the old gen at young collections can cause increases
670 // that don't feed back to the generation sizing policy until
671 // a full collection. Don't resize the old gen here.
672
673 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
674 size_policy->calculated_survivor_size_in_bytes());
675
676 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
677 }
678
679 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
680 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
681 // Also update() will case adaptive NUMA chunk resizing.
682 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
683 young_gen->eden_space()->update();
684
685 heap->gc_policy_counters()->update_counters();
686
687 heap->resize_all_tlabs();
688
689 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
690 }
691
692 #if COMPILER2_OR_JVMCI
693 DerivedPointerTable::update_pointers();
694 #endif
695
696 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
697
698 // Re-verify object start arrays
699 if (VerifyObjectStartArray &&
700 VerifyAfterGC) {
701 old_gen->verify_object_start_array();
702 }
703
704 // Verify all old -> young cards are now precise
705 if (VerifyRememberedSets) {
706 // Precise verification will give false positives. Until this is fixed,
707 // use imprecise verification.
708 // heap->card_table()->verify_all_young_refs_precise();
709 heap->card_table()->verify_all_young_refs_imprecise();
710 }
711
712 if (log_is_enabled(Debug, gc, heap, exit)) {
713 accumulated_time()->stop();
714 }
715
716 heap->print_heap_change(pre_gc_values);
717
718 // Track memory usage and detect low memory
719 MemoryService::track_memory_usage();
720 heap->update_counters();
721 }
722
723 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
724 HandleMark hm; // Discard invalid handles created during verification
725 Universe::verify("After GC");
726 }
727
728 heap->print_heap_after_gc();
729 heap->trace_heap_after_gc(&_gc_tracer);
730
731 scavenge_exit.update();
732
733 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
734 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
735 scavenge_exit.ticks());
736
737 #ifdef TRACESPINNING
738 ParallelTaskTerminator::print_termination_counts();
739 #endif
740
741 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
742
743 _gc_timer.register_gc_end();
744
745 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
746
747 return !promotion_failure_occurred;
748 }
749
750 // This method iterates over all objects in the young generation,
751 // removing all forwarding references. It then restores any preserved marks.
752 void PSScavenge::clean_up_failed_promotion() {
753 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
754 PSYoungGen* young_gen = heap->young_gen();
755
756 RemoveForwardedPointerClosure remove_fwd_ptr_closure;
757 young_gen->object_iterate(&remove_fwd_ptr_closure);
758
759 PSPromotionManager::restore_preserved_marks();
760
761 // Reset the PromotionFailureALot counters.
762 NOT_PRODUCT(heap->reset_promotion_should_fail();)
763 }
764
765 bool PSScavenge::should_attempt_scavenge() {
766 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
767 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
768
769 if (UsePerfData) {
770 counters->update_scavenge_skipped(not_skipped);
771 }
772
773 PSYoungGen* young_gen = heap->young_gen();
774 PSOldGen* old_gen = heap->old_gen();
775
776 // Do not attempt to promote unless to_space is empty
777 if (!young_gen->to_space()->is_empty()) {
778 _consecutive_skipped_scavenges++;
779 if (UsePerfData) {
780 counters->update_scavenge_skipped(to_space_not_empty);
781 }
782 return false;
783 }
784
785 // Test to see if the scavenge will likely fail.
786 PSAdaptiveSizePolicy* policy = heap->size_policy();
787
788 // A similar test is done in the policy's should_full_GC(). If this is
789 // changed, decide if that test should also be changed.
790 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
791 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
792 bool result = promotion_estimate < old_gen->free_in_bytes();
793
794 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT,
795 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(),
796 (size_t) policy->padded_average_promoted_in_bytes(),
797 old_gen->free_in_bytes());
798 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) {
799 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
800 }
801
802 if (result) {
803 _consecutive_skipped_scavenges = 0;
804 } else {
805 _consecutive_skipped_scavenges++;
806 if (UsePerfData) {
807 counters->update_scavenge_skipped(promoted_too_large);
808 }
809 }
810 return result;
811 }
812
813 // Adaptive size policy support. When the young generation/old generation
814 // boundary moves, _young_generation_boundary must be reset
815 void PSScavenge::set_young_generation_boundary(HeapWord* v) {
816 _young_generation_boundary = v;
817 if (UseCompressedOops) {
818 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode((oop)v);
819 }
820 }
821
822 void PSScavenge::initialize() {
823 // Arguments must have been parsed
824
825 if (AlwaysTenure || NeverTenure) {
826 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markWord::max_age + 1,
827 "MaxTenuringThreshold should be 0 or markWord::max_age + 1, but is %d", (int) MaxTenuringThreshold);
828 _tenuring_threshold = MaxTenuringThreshold;
829 } else {
830 // We want to smooth out our startup times for the AdaptiveSizePolicy
831 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
832 MaxTenuringThreshold;
833 }
834
835 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
836 PSYoungGen* young_gen = heap->young_gen();
837 PSOldGen* old_gen = heap->old_gen();
838
839 // Set boundary between young_gen and old_gen
840 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
841 "old above young");
842 set_young_generation_boundary(young_gen->eden_space()->bottom());
843
844 // Initialize ref handling object for scavenging.
845 _span_based_discoverer.set_span(young_gen->reserved());
846 _ref_processor =
847 new ReferenceProcessor(&_span_based_discoverer,
848 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
849 ParallelGCThreads, // mt processing degree
850 true, // mt discovery
851 ParallelGCThreads, // mt discovery degree
852 true, // atomic_discovery
853 NULL, // header provides liveness info
854 false);
855
856 // Cache the cardtable
857 _card_table = heap->card_table();
858
859 _counters = new CollectorCounters("Parallel young collection pauses", 0);
860 }