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/iterator.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "memory/universe.hpp"
58 #include "logging/log.hpp"
59 #include "oops/access.inline.hpp"
60 #include "oops/compressedOops.inline.hpp"
61 #include "oops/oop.inline.hpp"
62 #include "runtime/biasedLocking.hpp"
63 #include "runtime/handles.inline.hpp"
64 #include "runtime/threadCritical.hpp"
65 #include "runtime/vmThread.hpp"
66 #include "runtime/vmOperations.hpp"
67 #include "services/management.hpp"
68 #include "services/memoryService.hpp"
69 #include "utilities/stack.inline.hpp"
70
71 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
72 int PSScavenge::_consecutive_skipped_scavenges = 0;
73 SpanSubjectToDiscoveryClosure PSScavenge::_span_based_discoverer;
74 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
75 PSCardTable* PSScavenge::_card_table = NULL;
76 bool PSScavenge::_survivor_overflow = false;
77 uint PSScavenge::_tenuring_threshold = 0;
78 HeapWord* PSScavenge::_young_generation_boundary = NULL;
79 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
80 elapsedTimer PSScavenge::_accumulated_time;
81 STWGCTimer PSScavenge::_gc_timer;
82 ParallelScavengeTracer PSScavenge::_gc_tracer;
83 CollectorCounters* PSScavenge::_counters = NULL;
84
85 static void scavenge_roots_work(ParallelRootType::Value root_type, uint worker_id) {
86 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
87
88 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
89 PSScavengeRootsClosure roots_closure(pm);
90 PSPromoteRootsClosure roots_to_old_closure(pm);
91
92 switch (root_type) {
93 case ParallelRootType::universe:
94 Universe::oops_do(&roots_closure);
95 break;
96
97 case ParallelRootType::jni_handles:
98 JNIHandles::oops_do(&roots_closure);
99 break;
100
101 case ParallelRootType::object_synchronizer:
102 ObjectSynchronizer::oops_do(&roots_closure);
103 break;
104
105 case ParallelRootType::system_dictionary:
106 SystemDictionary::oops_do(&roots_closure);
107 break;
108
109 case ParallelRootType::class_loader_data:
110 {
111 PSScavengeCLDClosure cld_closure(pm);
112 ClassLoaderDataGraph::cld_do(&cld_closure);
113 }
114 break;
115
116 case ParallelRootType::management:
117 Management::oops_do(&roots_closure);
118 break;
119
120 case ParallelRootType::jvmti:
121 JvmtiExport::oops_do(&roots_closure);
122 break;
123
124 case ParallelRootType::code_cache:
125 {
126 MarkingCodeBlobClosure code_closure(&roots_to_old_closure, CodeBlobToOopClosure::FixRelocations);
127 ScavengableNMethods::nmethods_do(&code_closure);
128 AOTLoader::oops_do(&roots_closure);
129 }
130 break;
131
132 case ParallelRootType::sentinel:
133 DEBUG_ONLY(default:) // DEBUG_ONLY hack will create compile error on release builds (-Wswitch) and runtime check on debug builds
134 fatal("Bad enumeration value: %u", root_type);
135 break;
136 }
137
138 // Do the real work
139 pm->drain_stacks(false);
140 }
141
142 static void steal_work(ParallelTaskTerminator& terminator, uint worker_id) {
143 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
144
145 PSPromotionManager* pm =
146 PSPromotionManager::gc_thread_promotion_manager(worker_id);
147 pm->drain_stacks(true);
148 guarantee(pm->stacks_empty(),
149 "stacks should be empty at this point");
150
151 while (true) {
152 StarTask p;
153 if (PSPromotionManager::steal_depth(worker_id, p)) {
154 TASKQUEUE_STATS_ONLY(pm->record_steal(p));
155 pm->process_popped_location_depth(p);
156 pm->drain_stacks_depth(true);
157 } else {
158 if (terminator.offer_termination()) {
159 break;
160 }
161 }
162 }
163 guarantee(pm->stacks_empty(), "stacks should be empty at this point");
164 }
165
166 // Define before use
167 class PSIsAliveClosure: public BoolObjectClosure {
168 public:
169 bool do_object_b(oop p) {
170 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
171 }
172 };
173
174 PSIsAliveClosure PSScavenge::_is_alive_closure;
175
176 class PSKeepAliveClosure: public OopClosure {
177 protected:
178 MutableSpace* _to_space;
179 PSPromotionManager* _promotion_manager;
180
181 public:
182 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
183 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
184 _to_space = heap->young_gen()->to_space();
185
186 assert(_promotion_manager != NULL, "Sanity");
187 }
188
189 template <class T> void do_oop_work(T* p) {
190 assert (oopDesc::is_oop(RawAccess<IS_NOT_NULL>::oop_load(p)),
191 "expected an oop while scanning weak refs");
192
193 // Weak refs may be visited more than once.
194 if (PSScavenge::should_scavenge(p, _to_space)) {
195 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p);
196 }
197 }
198 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
199 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
200 };
201
202 class PSEvacuateFollowersClosure: public VoidClosure {
203 private:
204 PSPromotionManager* _promotion_manager;
205 public:
206 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
207
208 virtual void do_void() {
209 assert(_promotion_manager != NULL, "Sanity");
210 _promotion_manager->drain_stacks(true);
211 guarantee(_promotion_manager->stacks_empty(),
212 "stacks should be empty at this point");
213 }
214 };
215
216 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
217 virtual void execute(ProcessTask& process_task, uint ergo_workers);
218 };
219
220 class PSRefProcTask : public AbstractGangTask {
221 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
222 TaskTerminator _terminator;
223 ProcessTask& _task;
224 uint _active_workers;
225
226 public:
227 PSRefProcTask(ProcessTask& task, uint active_workers)
228 : AbstractGangTask("PSRefProcTask"),
229 _terminator(active_workers, PSPromotionManager::stack_array_depth()),
230 _task(task),
231 _active_workers(active_workers) {
232 }
233
234 virtual void work(uint worker_id) {
235 PSPromotionManager* promotion_manager =
236 PSPromotionManager::gc_thread_promotion_manager(worker_id);
237 assert(promotion_manager != NULL, "sanity check");
238 PSKeepAliveClosure keep_alive(promotion_manager);
239 PSEvacuateFollowersClosure evac_followers(promotion_manager);
240 PSIsAliveClosure is_alive;
241 _task.work(worker_id, is_alive, keep_alive, evac_followers);
242
243 if (_task.marks_oops_alive() && _active_workers > 1) {
244 steal_work(*_terminator.terminator(), worker_id);
245 }
246 }
247 };
248
249 void PSRefProcTaskExecutor::execute(ProcessTask& process_task, uint ergo_workers) {
250 PSRefProcTask task(process_task, ergo_workers);
251 ParallelScavengeHeap::heap()->workers().run_task(&task);
252 }
253
254 // This method contains all heap specific policy for invoking scavenge.
255 // PSScavenge::invoke_no_policy() will do nothing but attempt to
256 // scavenge. It will not clean up after failed promotions, bail out if
257 // we've exceeded policy time limits, or any other special behavior.
258 // All such policy should be placed here.
259 //
260 // Note that this method should only be called from the vm_thread while
261 // at a safepoint!
262 bool PSScavenge::invoke() {
263 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
264 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
265 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
266
267 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap();
268 PSAdaptiveSizePolicy* policy = heap->size_policy();
269 IsGCActiveMark mark;
270
271 const bool scavenge_done = PSScavenge::invoke_no_policy();
272 const bool need_full_gc = !scavenge_done ||
273 policy->should_full_GC(heap->old_gen()->free_in_bytes());
274 bool full_gc_done = false;
275
276 if (UsePerfData) {
277 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
278 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
279 counters->update_full_follows_scavenge(ffs_val);
280 }
281
282 if (need_full_gc) {
283 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
284 SoftRefPolicy* srp = heap->soft_ref_policy();
285 const bool clear_all_softrefs = srp->should_clear_all_soft_refs();
286
287 if (UseParallelOldGC) {
288 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
289 } else {
290 full_gc_done = PSMarkSweepProxy::invoke_no_policy(clear_all_softrefs);
291 }
292 }
293
294 return full_gc_done;
295 }
296
297 class PSThreadRootsTaskClosure : public ThreadClosure {
298 uint _worker_id;
299 public:
300 PSThreadRootsTaskClosure(uint worker_id) : _worker_id(worker_id) { }
301 virtual void do_thread(Thread* thread) {
302 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
303
304 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(_worker_id);
305 PSScavengeRootsClosure roots_closure(pm);
306 MarkingCodeBlobClosure roots_in_blobs(&roots_closure, CodeBlobToOopClosure::FixRelocations);
307
308 thread->oops_do(&roots_closure, &roots_in_blobs);
309
310 // Do the real work
311 pm->drain_stacks(false);
312 }
313 };
314
315 class ScavengeRootsTask : public AbstractGangTask {
316 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
317 SequentialSubTasksDone _subtasks;
318 PSOldGen* _old_gen;
319 HeapWord* _gen_top;
320 uint _active_workers;
321 bool _is_empty;
322 TaskTerminator _terminator;
323
324 public:
325 ScavengeRootsTask(PSOldGen* old_gen,
326 HeapWord* gen_top,
327 uint active_workers,
328 bool is_empty) :
329 AbstractGangTask("ScavengeRootsTask"),
330 _strong_roots_scope(active_workers),
331 _subtasks(),
332 _old_gen(old_gen),
333 _gen_top(gen_top),
334 _active_workers(active_workers),
335 _is_empty(is_empty),
336 _terminator(active_workers, PSPromotionManager::vm_thread_promotion_manager()->stack_array_depth()) {
337 _subtasks.set_n_threads(active_workers);
338 _subtasks.set_n_tasks(ParallelRootType::sentinel);
339 }
340
341 virtual void work(uint worker_id) {
342 ResourceMark rm;
343
344 if (!_is_empty) {
345 // There are only old-to-young pointers if there are objects
346 // in the old gen.
347
348 assert(_old_gen != NULL, "Sanity");
349 // There are no old-to-young pointers if the old gen is empty.
350 assert(!_old_gen->object_space()->is_empty(), "Should not be called is there is no work");
351 assert(_old_gen->object_space()->contains(_gen_top) || _gen_top == _old_gen->object_space()->top(), "Sanity");
352 assert(worker_id < ParallelGCThreads, "Sanity");
353
354 {
355 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
356 PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table();
357
358 card_table->scavenge_contents_parallel(_old_gen->start_array(),
359 _old_gen->object_space(),
360 _gen_top,
361 pm,
362 worker_id,
363 _active_workers);
364
365 // Do the real work
366 pm->drain_stacks(false);
367 }
368 }
369
370 for (uint root_type = 0; _subtasks.try_claim_task(root_type); /* empty */ ) {
371 scavenge_roots_work(static_cast<ParallelRootType::Value>(root_type), worker_id);
372 }
373 _subtasks.all_tasks_completed();
374
375 PSThreadRootsTaskClosure closure(worker_id);
376 Threads::possibly_parallel_threads_do(true /*parallel */, &closure);
377
378
379 // If active_workers can exceed 1, add a steal_work().
380 // PSPromotionManager::drain_stacks_depth() does not fully drain its
381 // stacks and expects a steal_work() to complete the draining if
382 // ParallelGCThreads is > 1.
383
384 if (_active_workers > 1) {
385 steal_work(*_terminator.terminator() , worker_id);
386 }
387 }
388 };
389
390 // This method contains no policy. You should probably
391 // be calling invoke() instead.
392 bool PSScavenge::invoke_no_policy() {
393 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
394 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
395
396 _gc_timer.register_gc_start();
397
398 TimeStamp scavenge_entry;
399 TimeStamp scavenge_midpoint;
400 TimeStamp scavenge_exit;
401
402 scavenge_entry.update();
403
404 if (GCLocker::check_active_before_gc()) {
405 return false;
406 }
407
408 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
409 GCCause::Cause gc_cause = heap->gc_cause();
410
411 // Check for potential problems.
412 if (!should_attempt_scavenge()) {
413 return false;
414 }
415
416 GCIdMark gc_id_mark;
417 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
418
419 bool promotion_failure_occurred = false;
420
421 PSYoungGen* young_gen = heap->young_gen();
422 PSOldGen* old_gen = heap->old_gen();
423 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
424
425 heap->increment_total_collections();
426
427 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
428 // Gather the feedback data for eden occupancy.
429 young_gen->eden_space()->accumulate_statistics();
430 }
431
432 heap->print_heap_before_gc();
433 heap->trace_heap_before_gc(&_gc_tracer);
434
435 assert(!NeverTenure || _tenuring_threshold == markWord::max_age + 1, "Sanity");
436 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
437
438 // Fill in TLABs
439 heap->ensure_parsability(true); // retire TLABs
440
441 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
442 HandleMark hm; // Discard invalid handles created during verification
443 Universe::verify("Before GC");
444 }
445
446 {
447 ResourceMark rm;
448 HandleMark hm;
449
450 GCTraceCPUTime tcpu;
451 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true);
452 TraceCollectorStats tcs(counters());
453 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause);
454
455 if (log_is_enabled(Debug, gc, heap, exit)) {
456 accumulated_time()->start();
457 }
458
459 // Let the size policy know we're starting
460 size_policy->minor_collection_begin();
461
462 // Verify the object start arrays.
463 if (VerifyObjectStartArray &&
464 VerifyBeforeGC) {
465 old_gen->verify_object_start_array();
466 }
467
468 // Verify no unmarked old->young roots
469 if (VerifyRememberedSets) {
470 heap->card_table()->verify_all_young_refs_imprecise();
471 }
472
473 assert(young_gen->to_space()->is_empty(),
474 "Attempt to scavenge with live objects in to_space");
475 young_gen->to_space()->clear(SpaceDecorator::Mangle);
476
477 save_to_space_top_before_gc();
478
479 #if COMPILER2_OR_JVMCI
480 DerivedPointerTable::clear();
481 #endif
482
483 reference_processor()->enable_discovery();
484 reference_processor()->setup_policy(false);
485
486 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
487
488 // Reset our survivor overflow.
489 set_survivor_overflow(false);
490
491 // We need to save the old top values before
492 // creating the promotion_manager. We pass the top
493 // values to the card_table, to prevent it from
494 // straying into the promotion labs.
495 HeapWord* old_top = old_gen->object_space()->top();
496
497 const uint active_workers =
498 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().total_workers(),
499 ParallelScavengeHeap::heap()->workers().active_workers(),
500 Threads::number_of_non_daemon_threads());
501 ParallelScavengeHeap::heap()->workers().update_active_workers(active_workers);
502
503 PSPromotionManager::pre_scavenge();
504
505 // We'll use the promotion manager again later.
506 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
507 {
508 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
509
510 ScavengeRootsTask task(old_gen, old_top, active_workers, old_gen->object_space()->is_empty());
511 ParallelScavengeHeap::heap()->workers().run_task(&task);
512 }
513
514 scavenge_midpoint.update();
515
516 // Process reference objects discovered during scavenge
517 {
518 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
519
520 reference_processor()->setup_policy(false); // not always_clear
521 reference_processor()->set_active_mt_degree(active_workers);
522 PSKeepAliveClosure keep_alive(promotion_manager);
523 PSEvacuateFollowersClosure evac_followers(promotion_manager);
524 ReferenceProcessorStats stats;
525 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->max_num_queues());
526 if (reference_processor()->processing_is_mt()) {
527 PSRefProcTaskExecutor task_executor;
528 stats = reference_processor()->process_discovered_references(
529 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
530 &pt);
531 } else {
532 stats = reference_processor()->process_discovered_references(
533 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt);
534 }
535
536 _gc_tracer.report_gc_reference_stats(stats);
537 pt.print_all_references();
538 }
539
540 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
541
542 PSScavengeRootsClosure root_closure(promotion_manager);
543
544 {
545 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
546 WeakProcessor::weak_oops_do(&_is_alive_closure, &root_closure);
547 }
548
549 // Verify that usage of root_closure didn't copy any objects.
550 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
551
552 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
553 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
554 if (promotion_failure_occurred) {
555 clean_up_failed_promotion();
556 log_info(gc, promotion)("Promotion failed");
557 }
558
559 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
560
561 // Let the size policy know we're done. Note that we count promotion
562 // failure cleanup time as part of the collection (otherwise, we're
563 // implicitly saying it's mutator time).
564 size_policy->minor_collection_end(gc_cause);
565
566 if (!promotion_failure_occurred) {
567 // Swap the survivor spaces.
568 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
569 young_gen->from_space()->clear(SpaceDecorator::Mangle);
570 young_gen->swap_spaces();
571
572 size_t survived = young_gen->from_space()->used_in_bytes();
573 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used();
574 size_policy->update_averages(_survivor_overflow, survived, promoted);
575
576 // A successful scavenge should restart the GC time limit count which is
577 // for full GC's.
578 size_policy->reset_gc_overhead_limit_count();
579 if (UseAdaptiveSizePolicy) {
580 // Calculate the new survivor size and tenuring threshold
581
582 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
583 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
584 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
585
586 if (UsePerfData) {
587 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
588 counters->update_old_eden_size(
589 size_policy->calculated_eden_size_in_bytes());
590 counters->update_old_promo_size(
591 size_policy->calculated_promo_size_in_bytes());
592 counters->update_old_capacity(old_gen->capacity_in_bytes());
593 counters->update_young_capacity(young_gen->capacity_in_bytes());
594 counters->update_survived(survived);
595 counters->update_promoted(promoted);
596 counters->update_survivor_overflowed(_survivor_overflow);
597 }
598
599 size_t max_young_size = young_gen->max_size();
600
601 // Deciding a free ratio in the young generation is tricky, so if
602 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
603 // that the old generation size may have been limited because of them) we
604 // should then limit our young generation size using NewRatio to have it
605 // follow the old generation size.
606 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
607 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
608 }
609
610 size_t survivor_limit =
611 size_policy->max_survivor_size(max_young_size);
612 _tenuring_threshold =
613 size_policy->compute_survivor_space_size_and_threshold(
614 _survivor_overflow,
615 _tenuring_threshold,
616 survivor_limit);
617
618 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")",
619 size_policy->calculated_survivor_size_in_bytes(),
620 _tenuring_threshold, MaxTenuringThreshold);
621
622 if (UsePerfData) {
623 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
624 counters->update_tenuring_threshold(_tenuring_threshold);
625 counters->update_survivor_size_counters();
626 }
627
628 // Do call at minor collections?
629 // Don't check if the size_policy is ready at this
630 // level. Let the size_policy check that internally.
631 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
632 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) {
633 // Calculate optimal free space amounts
634 assert(young_gen->max_size() >
635 young_gen->from_space()->capacity_in_bytes() +
636 young_gen->to_space()->capacity_in_bytes(),
637 "Sizes of space in young gen are out-of-bounds");
638
639 size_t young_live = young_gen->used_in_bytes();
640 size_t eden_live = young_gen->eden_space()->used_in_bytes();
641 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
642 size_t max_old_gen_size = old_gen->max_gen_size();
643 size_t max_eden_size = max_young_size -
644 young_gen->from_space()->capacity_in_bytes() -
645 young_gen->to_space()->capacity_in_bytes();
646
647 // Used for diagnostics
648 size_policy->clear_generation_free_space_flags();
649
650 size_policy->compute_eden_space_size(young_live,
651 eden_live,
652 cur_eden,
653 max_eden_size,
654 false /* not full gc*/);
655
656 size_policy->check_gc_overhead_limit(eden_live,
657 max_old_gen_size,
658 max_eden_size,
659 false /* not full gc*/,
660 gc_cause,
661 heap->soft_ref_policy());
662
663 size_policy->decay_supplemental_growth(false /* not full gc*/);
664 }
665 // Resize the young generation at every collection
666 // even if new sizes have not been calculated. This is
667 // to allow resizes that may have been inhibited by the
668 // relative location of the "to" and "from" spaces.
669
670 // Resizing the old gen at young collections can cause increases
671 // that don't feed back to the generation sizing policy until
672 // a full collection. Don't resize the old gen here.
673
674 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
675 size_policy->calculated_survivor_size_in_bytes());
676
677 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
678 }
679
680 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
681 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
682 // Also update() will case adaptive NUMA chunk resizing.
683 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
684 young_gen->eden_space()->update();
685
686 heap->gc_policy_counters()->update_counters();
687
688 heap->resize_all_tlabs();
689
690 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
691 }
692
693 #if COMPILER2_OR_JVMCI
694 DerivedPointerTable::update_pointers();
695 #endif
696
697 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
698
699 // Re-verify object start arrays
700 if (VerifyObjectStartArray &&
701 VerifyAfterGC) {
702 old_gen->verify_object_start_array();
703 }
704
705 // Verify all old -> young cards are now precise
706 if (VerifyRememberedSets) {
707 // Precise verification will give false positives. Until this is fixed,
708 // use imprecise verification.
709 // heap->card_table()->verify_all_young_refs_precise();
710 heap->card_table()->verify_all_young_refs_imprecise();
711 }
712
713 if (log_is_enabled(Debug, gc, heap, exit)) {
714 accumulated_time()->stop();
715 }
716
717 heap->print_heap_change(pre_gc_values);
718
719 // Track memory usage and detect low memory
720 MemoryService::track_memory_usage();
721 heap->update_counters();
722 }
723
724 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
725 HandleMark hm; // Discard invalid handles created during verification
726 Universe::verify("After GC");
727 }
728
729 heap->print_heap_after_gc();
730 heap->trace_heap_after_gc(&_gc_tracer);
731
732 scavenge_exit.update();
733
734 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
735 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
736 scavenge_exit.ticks());
737
738 #ifdef TRACESPINNING
739 ParallelTaskTerminator::print_termination_counts();
740 #endif
741
742 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
743
744 _gc_timer.register_gc_end();
745
746 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
747
748 return !promotion_failure_occurred;
749 }
750
751 // This method iterates over all objects in the young generation,
752 // removing all forwarding references. It then restores any preserved marks.
753 void PSScavenge::clean_up_failed_promotion() {
754 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
755 PSYoungGen* young_gen = heap->young_gen();
756
757 RemoveForwardedPointerClosure remove_fwd_ptr_closure;
758 young_gen->object_iterate(&remove_fwd_ptr_closure);
759
760 PSPromotionManager::restore_preserved_marks();
761
762 // Reset the PromotionFailureALot counters.
763 NOT_PRODUCT(heap->reset_promotion_should_fail();)
764 }
765
766 bool PSScavenge::should_attempt_scavenge() {
767 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
768 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
769
770 if (UsePerfData) {
771 counters->update_scavenge_skipped(not_skipped);
772 }
773
774 PSYoungGen* young_gen = heap->young_gen();
775 PSOldGen* old_gen = heap->old_gen();
776
777 // Do not attempt to promote unless to_space is empty
778 if (!young_gen->to_space()->is_empty()) {
779 _consecutive_skipped_scavenges++;
780 if (UsePerfData) {
781 counters->update_scavenge_skipped(to_space_not_empty);
782 }
783 return false;
784 }
785
786 // Test to see if the scavenge will likely fail.
787 PSAdaptiveSizePolicy* policy = heap->size_policy();
788
789 // A similar test is done in the policy's should_full_GC(). If this is
790 // changed, decide if that test should also be changed.
791 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
792 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
793 bool result = promotion_estimate < old_gen->free_in_bytes();
794
795 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT,
796 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(),
797 (size_t) policy->padded_average_promoted_in_bytes(),
798 old_gen->free_in_bytes());
799 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) {
800 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
801 }
802
803 if (result) {
804 _consecutive_skipped_scavenges = 0;
805 } else {
806 _consecutive_skipped_scavenges++;
807 if (UsePerfData) {
808 counters->update_scavenge_skipped(promoted_too_large);
809 }
810 }
811 return result;
812 }
813
814 // Adaptive size policy support. When the young generation/old generation
815 // boundary moves, _young_generation_boundary must be reset
816 void PSScavenge::set_young_generation_boundary(HeapWord* v) {
817 _young_generation_boundary = v;
818 if (UseCompressedOops) {
819 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode((oop)v);
820 }
821 }
822
823 void PSScavenge::initialize() {
824 // Arguments must have been parsed
825
826 if (AlwaysTenure || NeverTenure) {
827 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markWord::max_age + 1,
828 "MaxTenuringThreshold should be 0 or markWord::max_age + 1, but is %d", (int) MaxTenuringThreshold);
829 _tenuring_threshold = MaxTenuringThreshold;
830 } else {
831 // We want to smooth out our startup times for the AdaptiveSizePolicy
832 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
833 MaxTenuringThreshold;
834 }
835
836 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
837 PSYoungGen* young_gen = heap->young_gen();
838 PSOldGen* old_gen = heap->old_gen();
839
840 // Set boundary between young_gen and old_gen
841 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
842 "old above young");
843 set_young_generation_boundary(young_gen->eden_space()->bottom());
844
845 // Initialize ref handling object for scavenging.
846 _span_based_discoverer.set_span(young_gen->reserved());
847 _ref_processor =
848 new ReferenceProcessor(&_span_based_discoverer,
849 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
850 ParallelGCThreads, // mt processing degree
851 true, // mt discovery
852 ParallelGCThreads, // mt discovery degree
853 true, // atomic_discovery
854 NULL, // header provides liveness info
855 false);
856
857 // Cache the cardtable
858 _card_table = heap->card_table();
859
860 _counters = new CollectorCounters("Parallel young collection pauses", 0);
861 }