1 /*
2 * Copyright (c) 2002, 2016, 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/cardTableExtension.hpp"
29 #include "gc/parallel/gcTaskManager.hpp"
30 #include "gc/parallel/parallelScavengeHeap.hpp"
31 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
32 #include "gc/parallel/psMarkSweep.hpp"
33 #include "gc/parallel/psParallelCompact.inline.hpp"
34 #include "gc/parallel/psScavenge.inline.hpp"
35 #include "gc/parallel/psTasks.hpp"
36 #include "gc/shared/collectorPolicy.hpp"
37 #include "gc/shared/gcCause.hpp"
38 #include "gc/shared/gcHeapSummary.hpp"
39 #include "gc/shared/gcId.hpp"
40 #include "gc/shared/gcLocker.inline.hpp"
41 #include "gc/shared/gcTimer.hpp"
42 #include "gc/shared/gcTrace.hpp"
43 #include "gc/shared/gcTraceTime.inline.hpp"
44 #include "gc/shared/isGCActiveMark.hpp"
45 #include "gc/shared/referencePolicy.hpp"
46 #include "gc/shared/referenceProcessor.hpp"
47 #include "gc/shared/spaceDecorator.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "logging/log.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "runtime/biasedLocking.hpp"
52 #include "runtime/fprofiler.hpp"
53 #include "runtime/handles.inline.hpp"
54 #include "runtime/threadCritical.hpp"
55 #include "runtime/vmThread.hpp"
56 #include "runtime/vm_operations.hpp"
57 #include "services/memoryService.hpp"
58 #include "utilities/stack.inline.hpp"
59
60 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
61 int PSScavenge::_consecutive_skipped_scavenges = 0;
62 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
63 CardTableExtension* PSScavenge::_card_table = NULL;
64 bool PSScavenge::_survivor_overflow = false;
65 uint PSScavenge::_tenuring_threshold = 0;
66 HeapWord* PSScavenge::_young_generation_boundary = NULL;
67 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
68 elapsedTimer PSScavenge::_accumulated_time;
69 STWGCTimer PSScavenge::_gc_timer;
70 ParallelScavengeTracer PSScavenge::_gc_tracer;
71 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack;
72 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack;
73 CollectorCounters* PSScavenge::_counters = NULL;
74
75 // Define before use
76 class PSIsAliveClosure: public BoolObjectClosure {
77 public:
78 bool do_object_b(oop p) {
79 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
80 }
81 };
82
83 PSIsAliveClosure PSScavenge::_is_alive_closure;
84
85 class PSKeepAliveClosure: public OopClosure {
86 protected:
87 MutableSpace* _to_space;
88 PSPromotionManager* _promotion_manager;
89
90 public:
91 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
92 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
93 _to_space = heap->young_gen()->to_space();
94
95 assert(_promotion_manager != NULL, "Sanity");
96 }
97
98 template <class T> void do_oop_work(T* p) {
99 assert (!oopDesc::is_null(*p), "expected non-null ref");
100 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
101 "expected an oop while scanning weak refs");
102
103 // Weak refs may be visited more than once.
104 if (PSScavenge::should_scavenge(p, _to_space)) {
105 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p);
106 }
107 }
108 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
109 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
110 };
111
112 class PSEvacuateFollowersClosure: public VoidClosure {
113 private:
114 PSPromotionManager* _promotion_manager;
115 public:
116 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
117
118 virtual void do_void() {
119 assert(_promotion_manager != NULL, "Sanity");
120 _promotion_manager->drain_stacks(true);
121 guarantee(_promotion_manager->stacks_empty(),
122 "stacks should be empty at this point");
123 }
124 };
125
126 class PSPromotionFailedClosure : public ObjectClosure {
127 virtual void do_object(oop obj) {
128 if (obj->is_forwarded()) {
129 obj->init_mark();
130 }
131 }
132 };
133
134 class PSRefProcTaskProxy: public GCTask {
135 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
136 ProcessTask & _rp_task;
137 uint _work_id;
138 public:
139 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
140 : _rp_task(rp_task),
141 _work_id(work_id)
142 { }
143
144 private:
145 virtual char* name() { return (char *)"Process referents by policy in parallel"; }
146 virtual void do_it(GCTaskManager* manager, uint which);
147 };
148
149 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
150 {
151 PSPromotionManager* promotion_manager =
152 PSPromotionManager::gc_thread_promotion_manager(which);
153 assert(promotion_manager != NULL, "sanity check");
154 PSKeepAliveClosure keep_alive(promotion_manager);
155 PSEvacuateFollowersClosure evac_followers(promotion_manager);
156 PSIsAliveClosure is_alive;
157 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
158 }
159
160 class PSRefEnqueueTaskProxy: public GCTask {
161 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
162 EnqueueTask& _enq_task;
163 uint _work_id;
164
165 public:
166 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
167 : _enq_task(enq_task),
168 _work_id(work_id)
169 { }
170
171 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
172 virtual void do_it(GCTaskManager* manager, uint which)
173 {
174 _enq_task.work(_work_id);
175 }
176 };
177
178 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
179 virtual void execute(ProcessTask& task);
180 virtual void execute(EnqueueTask& task);
181 };
182
183 void PSRefProcTaskExecutor::execute(ProcessTask& task)
184 {
185 GCTaskQueue* q = GCTaskQueue::create();
186 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
187 for(uint i=0; i < manager->active_workers(); i++) {
188 q->enqueue(new PSRefProcTaskProxy(task, i));
189 }
190 ParallelTaskTerminator terminator(manager->active_workers(),
191 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
192 if (task.marks_oops_alive() && manager->active_workers() > 1) {
193 for (uint j = 0; j < manager->active_workers(); j++) {
194 q->enqueue(new StealTask(&terminator));
195 }
196 }
197 manager->execute_and_wait(q);
198 }
199
200
201 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
202 {
203 GCTaskQueue* q = GCTaskQueue::create();
204 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
205 for(uint i=0; i < manager->active_workers(); i++) {
206 q->enqueue(new PSRefEnqueueTaskProxy(task, i));
207 }
208 manager->execute_and_wait(q);
209 }
210
211 // This method contains all heap specific policy for invoking scavenge.
212 // PSScavenge::invoke_no_policy() will do nothing but attempt to
213 // scavenge. It will not clean up after failed promotions, bail out if
214 // we've exceeded policy time limits, or any other special behavior.
215 // All such policy should be placed here.
216 //
217 // Note that this method should only be called from the vm_thread while
218 // at a safepoint!
219 bool PSScavenge::invoke() {
220 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
221 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
222 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
223
224 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap();
225 PSAdaptiveSizePolicy* policy = heap->size_policy();
226 IsGCActiveMark mark;
227
228 const bool scavenge_done = PSScavenge::invoke_no_policy();
229 const bool need_full_gc = !scavenge_done ||
230 policy->should_full_GC(heap->old_gen()->free_in_bytes());
231 bool full_gc_done = false;
232
233 if (UsePerfData) {
234 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
235 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
236 counters->update_full_follows_scavenge(ffs_val);
237 }
238
239 if (need_full_gc) {
240 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
241 CollectorPolicy* cp = heap->collector_policy();
242 const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
243
244 if (UseParallelOldGC) {
245 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
246 } else {
247 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
248 }
249 }
250
251 return full_gc_done;
252 }
253
254 // This method contains no policy. You should probably
255 // be calling invoke() instead.
256 bool PSScavenge::invoke_no_policy() {
257 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
258 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
259
260 assert(_preserved_mark_stack.is_empty(), "should be empty");
261 assert(_preserved_oop_stack.is_empty(), "should be empty");
262
263 _gc_timer.register_gc_start();
264
265 TimeStamp scavenge_entry;
266 TimeStamp scavenge_midpoint;
267 TimeStamp scavenge_exit;
268
269 scavenge_entry.update();
270
271 if (GCLocker::check_active_before_gc()) {
272 return false;
273 }
274
275 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
276 GCCause::Cause gc_cause = heap->gc_cause();
277
278 // Check for potential problems.
279 if (!should_attempt_scavenge()) {
280 return false;
281 }
282
283 GCIdMark gc_id_mark;
284 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
285
286 bool promotion_failure_occurred = false;
287
288 PSYoungGen* young_gen = heap->young_gen();
289 PSOldGen* old_gen = heap->old_gen();
290 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
291
292 heap->increment_total_collections();
293
294 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
295 // Gather the feedback data for eden occupancy.
296 young_gen->eden_space()->accumulate_statistics();
297 }
298
299 heap->print_heap_before_gc();
300 heap->trace_heap_before_gc(&_gc_tracer);
301
302 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
303 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
304
305 // Fill in TLABs
306 heap->accumulate_statistics_all_tlabs();
307 heap->ensure_parsability(true); // retire TLABs
308
309 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
310 HandleMark hm; // Discard invalid handles created during verification
311 Universe::verify("Before GC");
312 }
313
314 {
315 ResourceMark rm;
316 HandleMark hm;
317
318 GCTraceCPUTime tcpu;
319 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true);
320 TraceCollectorStats tcs(counters());
321 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
322
323 if (TraceYoungGenTime) accumulated_time()->start();
324
325 // Let the size policy know we're starting
326 size_policy->minor_collection_begin();
327
328 // Verify the object start arrays.
329 if (VerifyObjectStartArray &&
330 VerifyBeforeGC) {
331 old_gen->verify_object_start_array();
332 }
333
334 // Verify no unmarked old->young roots
335 if (VerifyRememberedSets) {
336 CardTableExtension::verify_all_young_refs_imprecise();
337 }
338
339 assert(young_gen->to_space()->is_empty(),
340 "Attempt to scavenge with live objects in to_space");
341 young_gen->to_space()->clear(SpaceDecorator::Mangle);
342
343 save_to_space_top_before_gc();
344
345 #if defined(COMPILER2) || INCLUDE_JVMCI
346 DerivedPointerTable::clear();
347 #endif
348
349 reference_processor()->enable_discovery();
350 reference_processor()->setup_policy(false);
351
352 PreGCValues pre_gc_values(heap);
353
354 // Reset our survivor overflow.
355 set_survivor_overflow(false);
356
357 // We need to save the old top values before
358 // creating the promotion_manager. We pass the top
359 // values to the card_table, to prevent it from
360 // straying into the promotion labs.
361 HeapWord* old_top = old_gen->object_space()->top();
362
363 // Release all previously held resources
364 gc_task_manager()->release_all_resources();
365
366 // Set the number of GC threads to be used in this collection
367 gc_task_manager()->set_active_gang();
368 gc_task_manager()->task_idle_workers();
369 // Get the active number of workers here and use that value
370 // throughout the methods.
371 uint active_workers = gc_task_manager()->active_workers();
372
373 PSPromotionManager::pre_scavenge();
374
375 // We'll use the promotion manager again later.
376 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
377 {
378 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
379 ParallelScavengeHeap::ParStrongRootsScope psrs;
380
381 GCTaskQueue* q = GCTaskQueue::create();
382
383 if (!old_gen->object_space()->is_empty()) {
384 // There are only old-to-young pointers if there are objects
385 // in the old gen.
386 uint stripe_total = active_workers;
387 for(uint i=0; i < stripe_total; i++) {
388 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
389 }
390 }
391
392 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
393 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
394 // We scan the thread roots in parallel
395 Threads::create_thread_roots_tasks(q);
396 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
397 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
398 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
399 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
400 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data));
401 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
402 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
403
404 ParallelTaskTerminator terminator(
405 active_workers,
406 (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
407 if (active_workers > 1) {
408 for (uint j = 0; j < active_workers; j++) {
409 q->enqueue(new StealTask(&terminator));
410 }
411 }
412
413 gc_task_manager()->execute_and_wait(q);
414 }
415
416 scavenge_midpoint.update();
417
418 // Process reference objects discovered during scavenge
419 {
420 GCTraceTime(Debug, gc, phases) tm("References", &_gc_timer);
421
422 reference_processor()->setup_policy(false); // not always_clear
423 reference_processor()->set_active_mt_degree(active_workers);
424 PSKeepAliveClosure keep_alive(promotion_manager);
425 PSEvacuateFollowersClosure evac_followers(promotion_manager);
426 ReferenceProcessorStats stats;
427 if (reference_processor()->processing_is_mt()) {
428 PSRefProcTaskExecutor task_executor;
429 stats = reference_processor()->process_discovered_references(
430 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
431 &_gc_timer);
432 } else {
433 stats = reference_processor()->process_discovered_references(
434 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer);
435 }
436
437 _gc_tracer.report_gc_reference_stats(stats);
438
439 // Enqueue reference objects discovered during scavenge.
440 if (reference_processor()->processing_is_mt()) {
441 PSRefProcTaskExecutor task_executor;
442 reference_processor()->enqueue_discovered_references(&task_executor);
443 } else {
444 reference_processor()->enqueue_discovered_references(NULL);
445 }
446 }
447
448 {
449 GCTraceTime(Debug, gc, phases) tm("StringTable", &_gc_timer);
450 // Unlink any dead interned Strings and process the remaining live ones.
451 PSScavengeRootsClosure root_closure(promotion_manager);
452 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
453 }
454
455 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
456 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
457 if (promotion_failure_occurred) {
458 clean_up_failed_promotion();
459 log_info(gc)("Promotion failed");
460 }
461
462 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
463
464 // Let the size policy know we're done. Note that we count promotion
465 // failure cleanup time as part of the collection (otherwise, we're
466 // implicitly saying it's mutator time).
467 size_policy->minor_collection_end(gc_cause);
468
469 if (!promotion_failure_occurred) {
470 // Swap the survivor spaces.
471 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
472 young_gen->from_space()->clear(SpaceDecorator::Mangle);
473 young_gen->swap_spaces();
474
475 size_t survived = young_gen->from_space()->used_in_bytes();
476 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used();
477 size_policy->update_averages(_survivor_overflow, survived, promoted);
478
479 // A successful scavenge should restart the GC time limit count which is
480 // for full GC's.
481 size_policy->reset_gc_overhead_limit_count();
482 if (UseAdaptiveSizePolicy) {
483 // Calculate the new survivor size and tenuring threshold
484
485 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
486 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
487 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
488
489 if (UsePerfData) {
490 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
491 counters->update_old_eden_size(
492 size_policy->calculated_eden_size_in_bytes());
493 counters->update_old_promo_size(
494 size_policy->calculated_promo_size_in_bytes());
495 counters->update_old_capacity(old_gen->capacity_in_bytes());
496 counters->update_young_capacity(young_gen->capacity_in_bytes());
497 counters->update_survived(survived);
498 counters->update_promoted(promoted);
499 counters->update_survivor_overflowed(_survivor_overflow);
500 }
501
502 size_t max_young_size = young_gen->max_size();
503
504 // Deciding a free ratio in the young generation is tricky, so if
505 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
506 // that the old generation size may have been limited because of them) we
507 // should then limit our young generation size using NewRatio to have it
508 // follow the old generation size.
509 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
510 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
511 }
512
513 size_t survivor_limit =
514 size_policy->max_survivor_size(max_young_size);
515 _tenuring_threshold =
516 size_policy->compute_survivor_space_size_and_threshold(
517 _survivor_overflow,
518 _tenuring_threshold,
519 survivor_limit);
520
521 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")",
522 size_policy->calculated_survivor_size_in_bytes(),
523 _tenuring_threshold, MaxTenuringThreshold);
524
525 if (UsePerfData) {
526 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
527 counters->update_tenuring_threshold(_tenuring_threshold);
528 counters->update_survivor_size_counters();
529 }
530
531 // Do call at minor collections?
532 // Don't check if the size_policy is ready at this
533 // level. Let the size_policy check that internally.
534 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
535 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) {
536 // Calculate optimal free space amounts
537 assert(young_gen->max_size() >
538 young_gen->from_space()->capacity_in_bytes() +
539 young_gen->to_space()->capacity_in_bytes(),
540 "Sizes of space in young gen are out-of-bounds");
541
542 size_t young_live = young_gen->used_in_bytes();
543 size_t eden_live = young_gen->eden_space()->used_in_bytes();
544 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
545 size_t max_old_gen_size = old_gen->max_gen_size();
546 size_t max_eden_size = max_young_size -
547 young_gen->from_space()->capacity_in_bytes() -
548 young_gen->to_space()->capacity_in_bytes();
549
550 // Used for diagnostics
551 size_policy->clear_generation_free_space_flags();
552
553 size_policy->compute_eden_space_size(young_live,
554 eden_live,
555 cur_eden,
556 max_eden_size,
557 false /* not full gc*/);
558
559 size_policy->check_gc_overhead_limit(young_live,
560 eden_live,
561 max_old_gen_size,
562 max_eden_size,
563 false /* not full gc*/,
564 gc_cause,
565 heap->collector_policy());
566
567 size_policy->decay_supplemental_growth(false /* not full gc*/);
568 }
569 // Resize the young generation at every collection
570 // even if new sizes have not been calculated. This is
571 // to allow resizes that may have been inhibited by the
572 // relative location of the "to" and "from" spaces.
573
574 // Resizing the old gen at young collections can cause increases
575 // that don't feed back to the generation sizing policy until
576 // a full collection. Don't resize the old gen here.
577
578 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
579 size_policy->calculated_survivor_size_in_bytes());
580
581 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
582 }
583
584 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
585 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
586 // Also update() will case adaptive NUMA chunk resizing.
587 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
588 young_gen->eden_space()->update();
589
590 heap->gc_policy_counters()->update_counters();
591
592 heap->resize_all_tlabs();
593
594 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
595 }
596
597 #if defined(COMPILER2) || INCLUDE_JVMCI
598 DerivedPointerTable::update_pointers();
599 #endif
600
601 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
602
603 // Re-verify object start arrays
604 if (VerifyObjectStartArray &&
605 VerifyAfterGC) {
606 old_gen->verify_object_start_array();
607 }
608
609 // Verify all old -> young cards are now precise
610 if (VerifyRememberedSets) {
611 // Precise verification will give false positives. Until this is fixed,
612 // use imprecise verification.
613 // CardTableExtension::verify_all_young_refs_precise();
614 CardTableExtension::verify_all_young_refs_imprecise();
615 }
616
617 if (TraceYoungGenTime) accumulated_time()->stop();
618
619 young_gen->print_used_change(pre_gc_values.young_gen_used());
620 old_gen->print_used_change(pre_gc_values.old_gen_used());
621 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
622
623 // Track memory usage and detect low memory
624 MemoryService::track_memory_usage();
625 heap->update_counters();
626
627 gc_task_manager()->release_idle_workers();
628 }
629
630 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
631 HandleMark hm; // Discard invalid handles created during verification
632 Universe::verify("After GC");
633 }
634
635 heap->print_heap_after_gc();
636 heap->trace_heap_after_gc(&_gc_tracer);
637
638 scavenge_exit.update();
639
640 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
641 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
642 scavenge_exit.ticks());
643 gc_task_manager()->print_task_time_stamps();
644
645 #ifdef TRACESPINNING
646 ParallelTaskTerminator::print_termination_counts();
647 #endif
648
649 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
650
651 _gc_timer.register_gc_end();
652
653 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
654
655 return !promotion_failure_occurred;
656 }
657
658 // This method iterates over all objects in the young generation,
659 // unforwarding markOops. It then restores any preserved mark oops,
660 // and clears the _preserved_mark_stack.
661 void PSScavenge::clean_up_failed_promotion() {
662 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
663 PSYoungGen* young_gen = heap->young_gen();
664
665 {
666 ResourceMark rm;
667
668 // Unforward all pointers in the young gen.
669 PSPromotionFailedClosure unforward_closure;
670 young_gen->object_iterate(&unforward_closure);
671
672 log_trace(gc, ergo)("Restoring " SIZE_FORMAT " marks", _preserved_oop_stack.size());
673
674 // Restore any saved marks.
675 while (!_preserved_oop_stack.is_empty()) {
676 oop obj = _preserved_oop_stack.pop();
677 markOop mark = _preserved_mark_stack.pop();
678 obj->set_mark(mark);
679 }
680
681 // Clear the preserved mark and oop stack caches.
682 _preserved_mark_stack.clear(true);
683 _preserved_oop_stack.clear(true);
684 }
685
686 // Reset the PromotionFailureALot counters.
687 NOT_PRODUCT(heap->reset_promotion_should_fail();)
688 }
689
690 // This method is called whenever an attempt to promote an object
691 // fails. Some markOops will need preservation, some will not. Note
692 // that the entire eden is traversed after a failed promotion, with
693 // all forwarded headers replaced by the default markOop. This means
694 // it is not necessary to preserve most markOops.
695 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
696 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
697 // Should use per-worker private stacks here rather than
698 // locking a common pair of stacks.
699 ThreadCritical tc;
700 _preserved_oop_stack.push(obj);
701 _preserved_mark_stack.push(obj_mark);
702 }
703 }
704
705 bool PSScavenge::should_attempt_scavenge() {
706 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
707 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
708
709 if (UsePerfData) {
710 counters->update_scavenge_skipped(not_skipped);
711 }
712
713 PSYoungGen* young_gen = heap->young_gen();
714 PSOldGen* old_gen = heap->old_gen();
715
716 // Do not attempt to promote unless to_space is empty
717 if (!young_gen->to_space()->is_empty()) {
718 _consecutive_skipped_scavenges++;
719 if (UsePerfData) {
720 counters->update_scavenge_skipped(to_space_not_empty);
721 }
722 return false;
723 }
724
725 // Test to see if the scavenge will likely fail.
726 PSAdaptiveSizePolicy* policy = heap->size_policy();
727
728 // A similar test is done in the policy's should_full_GC(). If this is
729 // changed, decide if that test should also be changed.
730 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
731 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
732 bool result = promotion_estimate < old_gen->free_in_bytes();
733
734 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT,
735 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(),
736 (size_t) policy->padded_average_promoted_in_bytes(),
737 old_gen->free_in_bytes());
738 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) {
739 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
740 }
741
742 if (result) {
743 _consecutive_skipped_scavenges = 0;
744 } else {
745 _consecutive_skipped_scavenges++;
746 if (UsePerfData) {
747 counters->update_scavenge_skipped(promoted_too_large);
748 }
749 }
750 return result;
751 }
752
753 // Used to add tasks
754 GCTaskManager* const PSScavenge::gc_task_manager() {
755 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
756 "shouldn't return NULL");
757 return ParallelScavengeHeap::gc_task_manager();
758 }
759
760 // Adaptive size policy support. When the young generation/old generation
761 // boundary moves, _young_generation_boundary must be reset
762 void PSScavenge::set_young_generation_boundary(HeapWord* v) {
763 _young_generation_boundary = v;
764 if (UseCompressedOops) {
765 _young_generation_boundary_compressed = (uintptr_t)oopDesc::encode_heap_oop((oop)v);
766 }
767 }
768
769 void PSScavenge::initialize() {
770 // Arguments must have been parsed
771
772 if (AlwaysTenure || NeverTenure) {
773 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1,
774 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold);
775 _tenuring_threshold = MaxTenuringThreshold;
776 } else {
777 // We want to smooth out our startup times for the AdaptiveSizePolicy
778 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
779 MaxTenuringThreshold;
780 }
781
782 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
783 PSYoungGen* young_gen = heap->young_gen();
784 PSOldGen* old_gen = heap->old_gen();
785
786 // Set boundary between young_gen and old_gen
787 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
788 "old above young");
789 set_young_generation_boundary(young_gen->eden_space()->bottom());
790
791 // Initialize ref handling object for scavenging.
792 MemRegion mr = young_gen->reserved();
793
794 _ref_processor =
795 new ReferenceProcessor(mr, // span
796 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
797 ParallelGCThreads, // mt processing degree
798 true, // mt discovery
799 ParallelGCThreads, // mt discovery degree
800 true, // atomic_discovery
801 NULL); // header provides liveness info
802
803 // Cache the cardtable
804 _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set());
805
806 _counters = new CollectorCounters("PSScavenge", 0);
807 }