1 /*
2 * Copyright (c) 2002, 2018, 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 "classfile/stringTable.hpp"
27 #include "code/codeCache.hpp"
28 #include "gc/parallel/gcTaskManager.hpp"
29 #include "gc/parallel/parallelScavengeHeap.hpp"
30 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
31 #include "gc/parallel/psClosure.inline.hpp"
32 #include "gc/parallel/psMarkSweepProxy.hpp"
33 #include "gc/parallel/psParallelCompact.inline.hpp"
34 #include "gc/parallel/psPromotionManager.inline.hpp"
35 #include "gc/parallel/psScavenge.inline.hpp"
36 #include "gc/parallel/psTasks.hpp"
37 #include "gc/shared/collectorPolicy.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/isGCActiveMark.hpp"
46 #include "gc/shared/referencePolicy.hpp"
47 #include "gc/shared/referenceProcessor.hpp"
48 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
49 #include "gc/shared/spaceDecorator.hpp"
50 #include "gc/shared/weakProcessor.hpp"
51 #include "memory/resourceArea.hpp"
52 #include "logging/log.hpp"
53 #include "oops/access.inline.hpp"
54 #include "oops/compressedOops.inline.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "runtime/biasedLocking.hpp"
57 #include "runtime/handles.inline.hpp"
58 #include "runtime/threadCritical.hpp"
59 #include "runtime/vmThread.hpp"
60 #include "runtime/vm_operations.hpp"
61 #include "services/memoryService.hpp"
62 #include "utilities/stack.inline.hpp"
63
64 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
65 int PSScavenge::_consecutive_skipped_scavenges = 0;
66 SpanSubjectToDiscoveryClosure PSScavenge::_span_based_discoverer;
67 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
68 PSCardTable* PSScavenge::_card_table = NULL;
69 bool PSScavenge::_survivor_overflow = false;
70 uint PSScavenge::_tenuring_threshold = 0;
71 HeapWord* PSScavenge::_young_generation_boundary = NULL;
72 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
73 elapsedTimer PSScavenge::_accumulated_time;
74 STWGCTimer PSScavenge::_gc_timer;
75 ParallelScavengeTracer PSScavenge::_gc_tracer;
76 CollectorCounters* PSScavenge::_counters = NULL;
77
78 // Define before use
79 class PSIsAliveClosure: public BoolObjectClosure {
80 public:
81 bool do_object_b(oop p) {
82 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
83 }
84 };
85
86 PSIsAliveClosure PSScavenge::_is_alive_closure;
87
88 class PSKeepAliveClosure: public OopClosure {
89 protected:
90 MutableSpace* _to_space;
91 PSPromotionManager* _promotion_manager;
92
93 public:
94 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
95 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
96 _to_space = heap->young_gen()->to_space();
97
98 assert(_promotion_manager != NULL, "Sanity");
99 }
100
101 template <class T> void do_oop_work(T* p) {
102 assert (oopDesc::is_oop(RawAccess<IS_NOT_NULL>::oop_load(p)),
103 "expected an oop while scanning weak refs");
104
105 // Weak refs may be visited more than once.
106 if (PSScavenge::should_scavenge(p, _to_space)) {
107 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p);
108 }
109 }
110 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
111 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
112 };
113
114 class PSEvacuateFollowersClosure: public VoidClosure {
115 private:
116 PSPromotionManager* _promotion_manager;
117 public:
118 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
119
120 virtual void do_void() {
121 assert(_promotion_manager != NULL, "Sanity");
122 _promotion_manager->drain_stacks(true);
123 guarantee(_promotion_manager->stacks_empty(),
124 "stacks should be empty at this point");
125 }
126 };
127
128 class PSRefProcTaskProxy: public GCTask {
129 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
130 ProcessTask & _rp_task;
131 uint _work_id;
132 public:
133 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
134 : _rp_task(rp_task),
135 _work_id(work_id)
136 { }
137
138 private:
139 virtual char* name() { return (char *)"Process referents by policy in parallel"; }
140 virtual void do_it(GCTaskManager* manager, uint which);
141 };
142
143 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
144 {
145 PSPromotionManager* promotion_manager =
146 PSPromotionManager::gc_thread_promotion_manager(which);
147 assert(promotion_manager != NULL, "sanity check");
148 PSKeepAliveClosure keep_alive(promotion_manager);
149 PSEvacuateFollowersClosure evac_followers(promotion_manager);
150 PSIsAliveClosure is_alive;
151 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
152 }
153
154 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
155 virtual void execute(ProcessTask& task, uint ergo_workers);
156 };
157
158 void PSRefProcTaskExecutor::execute(ProcessTask& task, uint ergo_workers)
159 {
160 GCTaskQueue* q = GCTaskQueue::create();
161 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
162 uint active_workers = manager->active_workers();
163
164 assert(active_workers == ergo_workers,
165 "Ergonomically chosen workers (%u) must be equal to active workers (%u)",
166 ergo_workers, active_workers);
167
168 for(uint i=0; i < active_workers; i++) {
169 q->enqueue(new PSRefProcTaskProxy(task, i));
170 }
171 ParallelTaskTerminator terminator(active_workers,
172 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
173 if (task.marks_oops_alive() && active_workers > 1) {
174 for (uint j = 0; j < active_workers; j++) {
175 q->enqueue(new StealTask(&terminator));
176 }
177 }
178 manager->execute_and_wait(q);
179 }
180
181 // This method contains all heap specific policy for invoking scavenge.
182 // PSScavenge::invoke_no_policy() will do nothing but attempt to
183 // scavenge. It will not clean up after failed promotions, bail out if
184 // we've exceeded policy time limits, or any other special behavior.
185 // All such policy should be placed here.
186 //
187 // Note that this method should only be called from the vm_thread while
188 // at a safepoint!
189 bool PSScavenge::invoke() {
190 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
191 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
192 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
193
194 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap();
195 PSAdaptiveSizePolicy* policy = heap->size_policy();
196 IsGCActiveMark mark;
197
198 const bool scavenge_done = PSScavenge::invoke_no_policy();
199 const bool need_full_gc = !scavenge_done ||
200 policy->should_full_GC(heap->old_gen()->free_in_bytes());
201 bool full_gc_done = false;
202
203 if (UsePerfData) {
204 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
205 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
206 counters->update_full_follows_scavenge(ffs_val);
207 }
208
209 if (need_full_gc) {
210 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
211 SoftRefPolicy* srp = heap->soft_ref_policy();
212 const bool clear_all_softrefs = srp->should_clear_all_soft_refs();
213
214 if (UseParallelOldGC) {
215 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
216 } else {
217 full_gc_done = PSMarkSweepProxy::invoke_no_policy(clear_all_softrefs);
218 }
219 }
220
221 return full_gc_done;
222 }
223
224 class PSAddThreadRootsTaskClosure : public ThreadClosure {
225 private:
226 GCTaskQueue* _q;
227
228 public:
229 PSAddThreadRootsTaskClosure(GCTaskQueue* q) : _q(q) { }
230 void do_thread(Thread* t) {
231 _q->enqueue(new ThreadRootsTask(t));
232 }
233 };
234
235 // This method contains no policy. You should probably
236 // be calling invoke() instead.
237 bool PSScavenge::invoke_no_policy() {
238 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
239 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
240
241 _gc_timer.register_gc_start();
242
243 TimeStamp scavenge_entry;
244 TimeStamp scavenge_midpoint;
245 TimeStamp scavenge_exit;
246
247 scavenge_entry.update();
248
249 if (GCLocker::check_active_before_gc()) {
250 return false;
251 }
252
253 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
254 GCCause::Cause gc_cause = heap->gc_cause();
255
256 // Check for potential problems.
257 if (!should_attempt_scavenge()) {
258 return false;
259 }
260
261 GCIdMark gc_id_mark;
262 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
263
264 bool promotion_failure_occurred = false;
265
266 PSYoungGen* young_gen = heap->young_gen();
267 PSOldGen* old_gen = heap->old_gen();
268 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
269
270 heap->increment_total_collections();
271
272 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
273 // Gather the feedback data for eden occupancy.
274 young_gen->eden_space()->accumulate_statistics();
275 }
276
277 heap->print_heap_before_gc();
278 heap->trace_heap_before_gc(&_gc_tracer);
279
280 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
281 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
282
283 // Fill in TLABs
284 heap->ensure_parsability(true); // retire TLABs
285
286 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
287 HandleMark hm; // Discard invalid handles created during verification
288 Universe::verify("Before GC");
289 }
290
291 {
292 ResourceMark rm;
293 HandleMark hm;
294
295 GCTraceCPUTime tcpu;
296 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true);
297 TraceCollectorStats tcs(counters());
298 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause);
299
300 if (log_is_enabled(Debug, gc, heap, exit)) {
301 accumulated_time()->start();
302 }
303
304 // Let the size policy know we're starting
305 size_policy->minor_collection_begin();
306
307 // Verify the object start arrays.
308 if (VerifyObjectStartArray &&
309 VerifyBeforeGC) {
310 old_gen->verify_object_start_array();
311 }
312
313 // Verify no unmarked old->young roots
314 if (VerifyRememberedSets) {
315 heap->card_table()->verify_all_young_refs_imprecise();
316 }
317
318 assert(young_gen->to_space()->is_empty(),
319 "Attempt to scavenge with live objects in to_space");
320 young_gen->to_space()->clear(SpaceDecorator::Mangle);
321
322 save_to_space_top_before_gc();
323
324 #if COMPILER2_OR_JVMCI
325 DerivedPointerTable::clear();
326 #endif
327
328 reference_processor()->enable_discovery();
329 reference_processor()->setup_policy(false);
330
331 PreGCValues pre_gc_values(heap);
332
333 // Reset our survivor overflow.
334 set_survivor_overflow(false);
335
336 // We need to save the old top values before
337 // creating the promotion_manager. We pass the top
338 // values to the card_table, to prevent it from
339 // straying into the promotion labs.
340 HeapWord* old_top = old_gen->object_space()->top();
341
342 // Release all previously held resources
343 gc_task_manager()->release_all_resources();
344
345 // Set the number of GC threads to be used in this collection
346 gc_task_manager()->set_active_gang();
347 gc_task_manager()->task_idle_workers();
348 // Get the active number of workers here and use that value
349 // throughout the methods.
350 uint active_workers = gc_task_manager()->active_workers();
351
352 PSPromotionManager::pre_scavenge();
353
354 // We'll use the promotion manager again later.
355 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
356 {
357 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
358 ParallelScavengeHeap::ParStrongRootsScope psrs;
359
360 GCTaskQueue* q = GCTaskQueue::create();
361
362 if (!old_gen->object_space()->is_empty()) {
363 // There are only old-to-young pointers if there are objects
364 // in the old gen.
365 uint stripe_total = active_workers;
366 for(uint i=0; i < stripe_total; i++) {
367 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
368 }
369 }
370
371 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
372 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
373 // We scan the thread roots in parallel
374 PSAddThreadRootsTaskClosure cl(q);
375 Threads::java_threads_and_vm_thread_do(&cl);
376 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
377 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
378 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
379 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data));
380 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
381 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
382
383 ParallelTaskTerminator terminator(
384 active_workers,
385 (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
386 // If active_workers can exceed 1, add a StrealTask.
387 // PSPromotionManager::drain_stacks_depth() does not fully drain its
388 // stacks and expects a StealTask to complete the draining if
389 // ParallelGCThreads is > 1.
390 if (gc_task_manager()->workers() > 1) {
391 for (uint j = 0; j < active_workers; j++) {
392 q->enqueue(new StealTask(&terminator));
393 }
394 }
395
396 gc_task_manager()->execute_and_wait(q);
397 }
398
399 scavenge_midpoint.update();
400
401 // Process reference objects discovered during scavenge
402 {
403 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
404
405 reference_processor()->setup_policy(false); // not always_clear
406 reference_processor()->set_active_mt_degree(active_workers);
407 PSKeepAliveClosure keep_alive(promotion_manager);
408 PSEvacuateFollowersClosure evac_followers(promotion_manager);
409 ReferenceProcessorStats stats;
410 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->max_num_queues());
411 if (reference_processor()->processing_is_mt()) {
412 PSRefProcTaskExecutor task_executor;
413 stats = reference_processor()->process_discovered_references(
414 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
415 &pt);
416 } else {
417 stats = reference_processor()->process_discovered_references(
418 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt);
419 }
420
421 _gc_tracer.report_gc_reference_stats(stats);
422 pt.print_all_references();
423 }
424
425 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
426
427 PSScavengeRootsClosure root_closure(promotion_manager);
428
429 {
430 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
431 WeakProcessor::weak_oops_do(&_is_alive_closure, &root_closure);
432 }
433
434 {
435 GCTraceTime(Debug, gc, phases) tm("Scrub String Table", &_gc_timer);
436 // Unlink any dead interned Strings and process the remaining live ones.
437 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
438 }
439
440 // Verify that usage of root_closure didn't copy any objects.
441 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
442
443 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
444 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
445 if (promotion_failure_occurred) {
446 clean_up_failed_promotion();
447 log_info(gc, promotion)("Promotion failed");
448 }
449
450 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
451
452 // Let the size policy know we're done. Note that we count promotion
453 // failure cleanup time as part of the collection (otherwise, we're
454 // implicitly saying it's mutator time).
455 size_policy->minor_collection_end(gc_cause);
456
457 if (!promotion_failure_occurred) {
458 // Swap the survivor spaces.
459 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
460 young_gen->from_space()->clear(SpaceDecorator::Mangle);
461 young_gen->swap_spaces();
462
463 size_t survived = young_gen->from_space()->used_in_bytes();
464 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used();
465 size_policy->update_averages(_survivor_overflow, survived, promoted);
466
467 // A successful scavenge should restart the GC time limit count which is
468 // for full GC's.
469 size_policy->reset_gc_overhead_limit_count();
470 if (UseAdaptiveSizePolicy) {
471 // Calculate the new survivor size and tenuring threshold
472
473 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
474 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
475 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
476
477 if (UsePerfData) {
478 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
479 counters->update_old_eden_size(
480 size_policy->calculated_eden_size_in_bytes());
481 counters->update_old_promo_size(
482 size_policy->calculated_promo_size_in_bytes());
483 counters->update_old_capacity(old_gen->capacity_in_bytes());
484 counters->update_young_capacity(young_gen->capacity_in_bytes());
485 counters->update_survived(survived);
486 counters->update_promoted(promoted);
487 counters->update_survivor_overflowed(_survivor_overflow);
488 }
489
490 size_t max_young_size = young_gen->max_size();
491
492 // Deciding a free ratio in the young generation is tricky, so if
493 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
494 // that the old generation size may have been limited because of them) we
495 // should then limit our young generation size using NewRatio to have it
496 // follow the old generation size.
497 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
498 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
499 }
500
501 size_t survivor_limit =
502 size_policy->max_survivor_size(max_young_size);
503 _tenuring_threshold =
504 size_policy->compute_survivor_space_size_and_threshold(
505 _survivor_overflow,
506 _tenuring_threshold,
507 survivor_limit);
508
509 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")",
510 size_policy->calculated_survivor_size_in_bytes(),
511 _tenuring_threshold, MaxTenuringThreshold);
512
513 if (UsePerfData) {
514 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
515 counters->update_tenuring_threshold(_tenuring_threshold);
516 counters->update_survivor_size_counters();
517 }
518
519 // Do call at minor collections?
520 // Don't check if the size_policy is ready at this
521 // level. Let the size_policy check that internally.
522 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
523 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) {
524 // Calculate optimal free space amounts
525 assert(young_gen->max_size() >
526 young_gen->from_space()->capacity_in_bytes() +
527 young_gen->to_space()->capacity_in_bytes(),
528 "Sizes of space in young gen are out-of-bounds");
529
530 size_t young_live = young_gen->used_in_bytes();
531 size_t eden_live = young_gen->eden_space()->used_in_bytes();
532 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
533 size_t max_old_gen_size = old_gen->max_gen_size();
534 size_t max_eden_size = max_young_size -
535 young_gen->from_space()->capacity_in_bytes() -
536 young_gen->to_space()->capacity_in_bytes();
537
538 // Used for diagnostics
539 size_policy->clear_generation_free_space_flags();
540
541 size_policy->compute_eden_space_size(young_live,
542 eden_live,
543 cur_eden,
544 max_eden_size,
545 false /* not full gc*/);
546
547 size_policy->check_gc_overhead_limit(young_live,
548 eden_live,
549 max_old_gen_size,
550 max_eden_size,
551 false /* not full gc*/,
552 gc_cause,
553 heap->soft_ref_policy());
554
555 size_policy->decay_supplemental_growth(false /* not full gc*/);
556 }
557 // Resize the young generation at every collection
558 // even if new sizes have not been calculated. This is
559 // to allow resizes that may have been inhibited by the
560 // relative location of the "to" and "from" spaces.
561
562 // Resizing the old gen at young collections can cause increases
563 // that don't feed back to the generation sizing policy until
564 // a full collection. Don't resize the old gen here.
565
566 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
567 size_policy->calculated_survivor_size_in_bytes());
568
569 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
570 }
571
572 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
573 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
574 // Also update() will case adaptive NUMA chunk resizing.
575 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
576 young_gen->eden_space()->update();
577
578 heap->gc_policy_counters()->update_counters();
579
580 heap->resize_all_tlabs();
581
582 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
583 }
584
585 #if COMPILER2_OR_JVMCI
586 DerivedPointerTable::update_pointers();
587 #endif
588
589 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
590
591 // Re-verify object start arrays
592 if (VerifyObjectStartArray &&
593 VerifyAfterGC) {
594 old_gen->verify_object_start_array();
595 }
596
597 // Verify all old -> young cards are now precise
598 if (VerifyRememberedSets) {
599 // Precise verification will give false positives. Until this is fixed,
600 // use imprecise verification.
601 // heap->card_table()->verify_all_young_refs_precise();
602 heap->card_table()->verify_all_young_refs_imprecise();
603 }
604
605 if (log_is_enabled(Debug, gc, heap, exit)) {
606 accumulated_time()->stop();
607 }
608
609 young_gen->print_used_change(pre_gc_values.young_gen_used());
610 old_gen->print_used_change(pre_gc_values.old_gen_used());
611 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used());
612
613 // Track memory usage and detect low memory
614 MemoryService::track_memory_usage();
615 heap->update_counters();
616
617 gc_task_manager()->release_idle_workers();
618 }
619
620 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
621 HandleMark hm; // Discard invalid handles created during verification
622 Universe::verify("After GC");
623 }
624
625 heap->print_heap_after_gc();
626 heap->trace_heap_after_gc(&_gc_tracer);
627
628 scavenge_exit.update();
629
630 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
631 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
632 scavenge_exit.ticks());
633 gc_task_manager()->print_task_time_stamps();
634
635 #ifdef TRACESPINNING
636 ParallelTaskTerminator::print_termination_counts();
637 #endif
638
639 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
640
641 _gc_timer.register_gc_end();
642
643 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
644
645 return !promotion_failure_occurred;
646 }
647
648 // This method iterates over all objects in the young generation,
649 // removing all forwarding references. It then restores any preserved marks.
650 void PSScavenge::clean_up_failed_promotion() {
651 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
652 PSYoungGen* young_gen = heap->young_gen();
653
654 RemoveForwardedPointerClosure remove_fwd_ptr_closure;
655 young_gen->object_iterate(&remove_fwd_ptr_closure);
656
657 PSPromotionManager::restore_preserved_marks();
658
659 // Reset the PromotionFailureALot counters.
660 NOT_PRODUCT(heap->reset_promotion_should_fail();)
661 }
662
663 bool PSScavenge::should_attempt_scavenge() {
664 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
665 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
666
667 if (UsePerfData) {
668 counters->update_scavenge_skipped(not_skipped);
669 }
670
671 PSYoungGen* young_gen = heap->young_gen();
672 PSOldGen* old_gen = heap->old_gen();
673
674 // Do not attempt to promote unless to_space is empty
675 if (!young_gen->to_space()->is_empty()) {
676 _consecutive_skipped_scavenges++;
677 if (UsePerfData) {
678 counters->update_scavenge_skipped(to_space_not_empty);
679 }
680 return false;
681 }
682
683 // Test to see if the scavenge will likely fail.
684 PSAdaptiveSizePolicy* policy = heap->size_policy();
685
686 // A similar test is done in the policy's should_full_GC(). If this is
687 // changed, decide if that test should also be changed.
688 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
689 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
690 bool result = promotion_estimate < old_gen->free_in_bytes();
691
692 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT,
693 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(),
694 (size_t) policy->padded_average_promoted_in_bytes(),
695 old_gen->free_in_bytes());
696 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) {
697 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
698 }
699
700 if (result) {
701 _consecutive_skipped_scavenges = 0;
702 } else {
703 _consecutive_skipped_scavenges++;
704 if (UsePerfData) {
705 counters->update_scavenge_skipped(promoted_too_large);
706 }
707 }
708 return result;
709 }
710
711 // Used to add tasks
712 GCTaskManager* const PSScavenge::gc_task_manager() {
713 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
714 "shouldn't return NULL");
715 return ParallelScavengeHeap::gc_task_manager();
716 }
717
718 // Adaptive size policy support. When the young generation/old generation
719 // boundary moves, _young_generation_boundary must be reset
720 void PSScavenge::set_young_generation_boundary(HeapWord* v) {
721 _young_generation_boundary = v;
722 if (UseCompressedOops) {
723 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode((oop)v);
724 }
725 }
726
727 void PSScavenge::initialize() {
728 // Arguments must have been parsed
729
730 if (AlwaysTenure || NeverTenure) {
731 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1,
732 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold);
733 _tenuring_threshold = MaxTenuringThreshold;
734 } else {
735 // We want to smooth out our startup times for the AdaptiveSizePolicy
736 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
737 MaxTenuringThreshold;
738 }
739
740 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
741 PSYoungGen* young_gen = heap->young_gen();
742 PSOldGen* old_gen = heap->old_gen();
743
744 // Set boundary between young_gen and old_gen
745 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
746 "old above young");
747 set_young_generation_boundary(young_gen->eden_space()->bottom());
748
749 // Initialize ref handling object for scavenging.
750 _span_based_discoverer.set_span(young_gen->reserved());
751 _ref_processor =
752 new ReferenceProcessor(&_span_based_discoverer,
753 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
754 ParallelGCThreads, // mt processing degree
755 true, // mt discovery
756 ParallelGCThreads, // mt discovery degree
757 true, // atomic_discovery
758 NULL, // header provides liveness info
759 false);
760
761 // Cache the cardtable
762 _card_table = heap->card_table();
763
764 _counters = new CollectorCounters("PSScavenge", 0);
765 }