1 /*
2 * Copyright (c) 2002, 2020, 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/psParallelCompact.inline.hpp"
35 #include "gc/parallel/psPromotionManager.inline.hpp"
36 #include "gc/parallel/psRootType.hpp"
37 #include "gc/parallel/psScavenge.inline.hpp"
38 #include "gc/shared/gcCause.hpp"
39 #include "gc/shared/gcHeapSummary.hpp"
40 #include "gc/shared/gcId.hpp"
41 #include "gc/shared/gcLocker.hpp"
42 #include "gc/shared/gcTimer.hpp"
43 #include "gc/shared/gcTrace.hpp"
44 #include "gc/shared/gcTraceTime.inline.hpp"
45 #include "gc/shared/isGCActiveMark.hpp"
46 #include "gc/shared/referencePolicy.hpp"
47 #include "gc/shared/referenceProcessor.hpp"
48 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
49 #include "gc/shared/scavengableNMethods.hpp"
50 #include "gc/shared/spaceDecorator.inline.hpp"
51 #include "gc/shared/weakProcessor.hpp"
52 #include "gc/shared/workerPolicy.hpp"
53 #include "gc/shared/workgroup.hpp"
54 #include "memory/iterator.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 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
287 }
288
289 return full_gc_done;
290 }
291
292 class PSThreadRootsTaskClosure : public ThreadClosure {
293 uint _worker_id;
294 public:
295 PSThreadRootsTaskClosure(uint worker_id) : _worker_id(worker_id) { }
296 virtual void do_thread(Thread* thread) {
297 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
298
299 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(_worker_id);
300 PSScavengeRootsClosure roots_closure(pm);
301 MarkingCodeBlobClosure roots_in_blobs(&roots_closure, CodeBlobToOopClosure::FixRelocations);
302
303 thread->oops_do(&roots_closure, &roots_in_blobs);
304
305 // Do the real work
306 pm->drain_stacks(false);
307 }
308 };
309
310 class ScavengeRootsTask : public AbstractGangTask {
311 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
312 SequentialSubTasksDone _subtasks;
313 PSOldGen* _old_gen;
314 HeapWord* _gen_top;
315 uint _active_workers;
316 bool _is_empty;
317 TaskTerminator _terminator;
318
319 public:
320 ScavengeRootsTask(PSOldGen* old_gen,
321 HeapWord* gen_top,
322 uint active_workers,
323 bool is_empty) :
324 AbstractGangTask("ScavengeRootsTask"),
325 _strong_roots_scope(active_workers),
326 _subtasks(),
327 _old_gen(old_gen),
328 _gen_top(gen_top),
329 _active_workers(active_workers),
330 _is_empty(is_empty),
331 _terminator(active_workers, PSPromotionManager::vm_thread_promotion_manager()->stack_array_depth()) {
332 _subtasks.set_n_threads(active_workers);
333 _subtasks.set_n_tasks(ParallelRootType::sentinel);
334 }
335
336 virtual void work(uint worker_id) {
337 ResourceMark rm;
338
339 if (!_is_empty) {
340 // There are only old-to-young pointers if there are objects
341 // in the old gen.
342
343 assert(_old_gen != NULL, "Sanity");
344 // There are no old-to-young pointers if the old gen is empty.
345 assert(!_old_gen->object_space()->is_empty(), "Should not be called is there is no work");
346 assert(_old_gen->object_space()->contains(_gen_top) || _gen_top == _old_gen->object_space()->top(), "Sanity");
347 assert(worker_id < ParallelGCThreads, "Sanity");
348
349 {
350 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id);
351 PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table();
352
353 card_table->scavenge_contents_parallel(_old_gen->start_array(),
354 _old_gen->object_space(),
355 _gen_top,
356 pm,
357 worker_id,
358 _active_workers);
359
360 // Do the real work
361 pm->drain_stacks(false);
362 }
363 }
364
365 for (uint root_type = 0; _subtasks.try_claim_task(root_type); /* empty */ ) {
366 scavenge_roots_work(static_cast<ParallelRootType::Value>(root_type), worker_id);
367 }
368 _subtasks.all_tasks_completed();
369
370 PSThreadRootsTaskClosure closure(worker_id);
371 Threads::possibly_parallel_threads_do(true /*parallel */, &closure);
372
373
374 // If active_workers can exceed 1, add a steal_work().
375 // PSPromotionManager::drain_stacks_depth() does not fully drain its
376 // stacks and expects a steal_work() to complete the draining if
377 // ParallelGCThreads is > 1.
378
379 if (_active_workers > 1) {
380 steal_work(*_terminator.terminator() , worker_id);
381 }
382 }
383 };
384
385 // This method contains no policy. You should probably
386 // be calling invoke() instead.
387 bool PSScavenge::invoke_no_policy() {
388 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
389 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
390
391 _gc_timer.register_gc_start();
392
393 TimeStamp scavenge_entry;
394 TimeStamp scavenge_midpoint;
395 TimeStamp scavenge_exit;
396
397 scavenge_entry.update();
398
399 if (GCLocker::check_active_before_gc()) {
400 return false;
401 }
402
403 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
404 GCCause::Cause gc_cause = heap->gc_cause();
405
406 // Check for potential problems.
407 if (!should_attempt_scavenge()) {
408 return false;
409 }
410
411 GCIdMark gc_id_mark;
412 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
413
414 bool promotion_failure_occurred = false;
415
416 PSYoungGen* young_gen = heap->young_gen();
417 PSOldGen* old_gen = heap->old_gen();
418 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
419
420 heap->increment_total_collections();
421
422 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
423 // Gather the feedback data for eden occupancy.
424 young_gen->eden_space()->accumulate_statistics();
425 }
426
427 heap->print_heap_before_gc();
428 heap->trace_heap_before_gc(&_gc_tracer);
429
430 assert(!NeverTenure || _tenuring_threshold == markWord::max_age + 1, "Sanity");
431 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
432
433 // Fill in TLABs
434 heap->ensure_parsability(true); // retire TLABs
435
436 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
437 HandleMark hm; // Discard invalid handles created during verification
438 Universe::verify("Before GC");
439 }
440
441 {
442 ResourceMark rm;
443 HandleMark hm;
444
445 GCTraceCPUTime tcpu;
446 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true);
447 TraceCollectorStats tcs(counters());
448 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause);
449
450 if (log_is_enabled(Debug, gc, heap, exit)) {
451 accumulated_time()->start();
452 }
453
454 // Let the size policy know we're starting
455 size_policy->minor_collection_begin();
456
457 // Verify the object start arrays.
458 if (VerifyObjectStartArray &&
459 VerifyBeforeGC) {
460 old_gen->verify_object_start_array();
461 }
462
463 // Verify no unmarked old->young roots
464 if (VerifyRememberedSets) {
465 heap->card_table()->verify_all_young_refs_imprecise();
466 }
467
468 assert(young_gen->to_space()->is_empty(),
469 "Attempt to scavenge with live objects in to_space");
470 young_gen->to_space()->clear(SpaceDecorator::Mangle);
471
472 save_to_space_top_before_gc();
473
474 #if COMPILER2_OR_JVMCI
475 DerivedPointerTable::clear();
476 #endif
477
478 reference_processor()->enable_discovery();
479 reference_processor()->setup_policy(false);
480
481 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
482
483 // Reset our survivor overflow.
484 set_survivor_overflow(false);
485
486 // We need to save the old top values before
487 // creating the promotion_manager. We pass the top
488 // values to the card_table, to prevent it from
489 // straying into the promotion labs.
490 HeapWord* old_top = old_gen->object_space()->top();
491
492 const uint active_workers =
493 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().total_workers(),
494 ParallelScavengeHeap::heap()->workers().active_workers(),
495 Threads::number_of_non_daemon_threads());
496 ParallelScavengeHeap::heap()->workers().update_active_workers(active_workers);
497
498 PSPromotionManager::pre_scavenge();
499
500 // We'll use the promotion manager again later.
501 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
502 {
503 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
504
505 ScavengeRootsTask task(old_gen, old_top, active_workers, old_gen->object_space()->is_empty());
506 ParallelScavengeHeap::heap()->workers().run_task(&task);
507 }
508
509 scavenge_midpoint.update();
510
511 // Process reference objects discovered during scavenge
512 {
513 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
514
515 reference_processor()->setup_policy(false); // not always_clear
516 reference_processor()->set_active_mt_degree(active_workers);
517 PSKeepAliveClosure keep_alive(promotion_manager);
518 PSEvacuateFollowersClosure evac_followers(promotion_manager);
519 ReferenceProcessorStats stats;
520 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->max_num_queues());
521 if (reference_processor()->processing_is_mt()) {
522 PSRefProcTaskExecutor task_executor;
523 stats = reference_processor()->process_discovered_references(
524 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
525 &pt);
526 } else {
527 stats = reference_processor()->process_discovered_references(
528 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt);
529 }
530
531 _gc_tracer.report_gc_reference_stats(stats);
532 pt.print_all_references();
533 }
534
535 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
536
537 PSScavengeRootsClosure root_closure(promotion_manager);
538
539 {
540 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
541 WeakProcessor::weak_oops_do(&_is_alive_closure, &root_closure);
542 }
543
544 // Verify that usage of root_closure didn't copy any objects.
545 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
546
547 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
548 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
549 if (promotion_failure_occurred) {
550 clean_up_failed_promotion();
551 log_info(gc, promotion)("Promotion failed");
552 }
553
554 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
555
556 // Let the size policy know we're done. Note that we count promotion
557 // failure cleanup time as part of the collection (otherwise, we're
558 // implicitly saying it's mutator time).
559 size_policy->minor_collection_end(gc_cause);
560
561 if (!promotion_failure_occurred) {
562 // Swap the survivor spaces.
563 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
564 young_gen->from_space()->clear(SpaceDecorator::Mangle);
565 young_gen->swap_spaces();
566
567 size_t survived = young_gen->from_space()->used_in_bytes();
568 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used();
569 size_policy->update_averages(_survivor_overflow, survived, promoted);
570
571 // A successful scavenge should restart the GC time limit count which is
572 // for full GC's.
573 size_policy->reset_gc_overhead_limit_count();
574 if (UseAdaptiveSizePolicy) {
575 // Calculate the new survivor size and tenuring threshold
576
577 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
578 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
579 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
580
581 if (UsePerfData) {
582 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
583 counters->update_old_eden_size(
584 size_policy->calculated_eden_size_in_bytes());
585 counters->update_old_promo_size(
586 size_policy->calculated_promo_size_in_bytes());
587 counters->update_old_capacity(old_gen->capacity_in_bytes());
588 counters->update_young_capacity(young_gen->capacity_in_bytes());
589 counters->update_survived(survived);
590 counters->update_promoted(promoted);
591 counters->update_survivor_overflowed(_survivor_overflow);
592 }
593
594 size_t max_young_size = young_gen->max_size();
595
596 // Deciding a free ratio in the young generation is tricky, so if
597 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
598 // that the old generation size may have been limited because of them) we
599 // should then limit our young generation size using NewRatio to have it
600 // follow the old generation size.
601 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
602 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
603 }
604
605 size_t survivor_limit =
606 size_policy->max_survivor_size(max_young_size);
607 _tenuring_threshold =
608 size_policy->compute_survivor_space_size_and_threshold(
609 _survivor_overflow,
610 _tenuring_threshold,
611 survivor_limit);
612
613 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")",
614 size_policy->calculated_survivor_size_in_bytes(),
615 _tenuring_threshold, MaxTenuringThreshold);
616
617 if (UsePerfData) {
618 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
619 counters->update_tenuring_threshold(_tenuring_threshold);
620 counters->update_survivor_size_counters();
621 }
622
623 // Do call at minor collections?
624 // Don't check if the size_policy is ready at this
625 // level. Let the size_policy check that internally.
626 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
627 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) {
628 // Calculate optimal free space amounts
629 assert(young_gen->max_size() >
630 young_gen->from_space()->capacity_in_bytes() +
631 young_gen->to_space()->capacity_in_bytes(),
632 "Sizes of space in young gen are out-of-bounds");
633
634 size_t young_live = young_gen->used_in_bytes();
635 size_t eden_live = young_gen->eden_space()->used_in_bytes();
636 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
637 size_t max_old_gen_size = old_gen->max_gen_size();
638 size_t max_eden_size = max_young_size -
639 young_gen->from_space()->capacity_in_bytes() -
640 young_gen->to_space()->capacity_in_bytes();
641
642 // Used for diagnostics
643 size_policy->clear_generation_free_space_flags();
644
645 size_policy->compute_eden_space_size(young_live,
646 eden_live,
647 cur_eden,
648 max_eden_size,
649 false /* not full gc*/);
650
651 size_policy->check_gc_overhead_limit(eden_live,
652 max_old_gen_size,
653 max_eden_size,
654 false /* not full gc*/,
655 gc_cause,
656 heap->soft_ref_policy());
657
658 size_policy->decay_supplemental_growth(false /* not full gc*/);
659 }
660 // Resize the young generation at every collection
661 // even if new sizes have not been calculated. This is
662 // to allow resizes that may have been inhibited by the
663 // relative location of the "to" and "from" spaces.
664
665 // Resizing the old gen at young collections can cause increases
666 // that don't feed back to the generation sizing policy until
667 // a full collection. Don't resize the old gen here.
668
669 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
670 size_policy->calculated_survivor_size_in_bytes());
671
672 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
673 }
674
675 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
676 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
677 // Also update() will case adaptive NUMA chunk resizing.
678 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
679 young_gen->eden_space()->update();
680
681 heap->gc_policy_counters()->update_counters();
682
683 heap->resize_all_tlabs();
684
685 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
686 }
687
688 #if COMPILER2_OR_JVMCI
689 DerivedPointerTable::update_pointers();
690 #endif
691
692 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
693
694 // Re-verify object start arrays
695 if (VerifyObjectStartArray &&
696 VerifyAfterGC) {
697 old_gen->verify_object_start_array();
698 }
699
700 // Verify all old -> young cards are now precise
701 if (VerifyRememberedSets) {
702 // Precise verification will give false positives. Until this is fixed,
703 // use imprecise verification.
704 // heap->card_table()->verify_all_young_refs_precise();
705 heap->card_table()->verify_all_young_refs_imprecise();
706 }
707
708 if (log_is_enabled(Debug, gc, heap, exit)) {
709 accumulated_time()->stop();
710 }
711
712 heap->print_heap_change(pre_gc_values);
713
714 // Track memory usage and detect low memory
715 MemoryService::track_memory_usage();
716 heap->update_counters();
717 }
718
719 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
720 HandleMark hm; // Discard invalid handles created during verification
721 Universe::verify("After GC");
722 }
723
724 heap->print_heap_after_gc();
725 heap->trace_heap_after_gc(&_gc_tracer);
726
727 scavenge_exit.update();
728
729 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
730 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
731 scavenge_exit.ticks());
732
733 #ifdef TRACESPINNING
734 ParallelTaskTerminator::print_termination_counts();
735 #endif
736
737 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
738
739 _gc_timer.register_gc_end();
740
741 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
742
743 return !promotion_failure_occurred;
744 }
745
746 // This method iterates over all objects in the young generation,
747 // removing all forwarding references. It then restores any preserved marks.
748 void PSScavenge::clean_up_failed_promotion() {
749 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
750 PSYoungGen* young_gen = heap->young_gen();
751
752 RemoveForwardedPointerClosure remove_fwd_ptr_closure;
753 young_gen->object_iterate(&remove_fwd_ptr_closure);
754
755 PSPromotionManager::restore_preserved_marks();
756
757 // Reset the PromotionFailureALot counters.
758 NOT_PRODUCT(heap->reset_promotion_should_fail();)
759 }
760
761 bool PSScavenge::should_attempt_scavenge() {
762 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
763 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
764
765 if (UsePerfData) {
766 counters->update_scavenge_skipped(not_skipped);
767 }
768
769 PSYoungGen* young_gen = heap->young_gen();
770 PSOldGen* old_gen = heap->old_gen();
771
772 // Do not attempt to promote unless to_space is empty
773 if (!young_gen->to_space()->is_empty()) {
774 _consecutive_skipped_scavenges++;
775 if (UsePerfData) {
776 counters->update_scavenge_skipped(to_space_not_empty);
777 }
778 return false;
779 }
780
781 // Test to see if the scavenge will likely fail.
782 PSAdaptiveSizePolicy* policy = heap->size_policy();
783
784 // A similar test is done in the policy's should_full_GC(). If this is
785 // changed, decide if that test should also be changed.
786 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
787 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
788 bool result = promotion_estimate < old_gen->free_in_bytes();
789
790 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT,
791 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(),
792 (size_t) policy->padded_average_promoted_in_bytes(),
793 old_gen->free_in_bytes());
794 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) {
795 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
796 }
797
798 if (result) {
799 _consecutive_skipped_scavenges = 0;
800 } else {
801 _consecutive_skipped_scavenges++;
802 if (UsePerfData) {
803 counters->update_scavenge_skipped(promoted_too_large);
804 }
805 }
806 return result;
807 }
808
809 // Adaptive size policy support. When the young generation/old generation
810 // boundary moves, _young_generation_boundary must be reset
811 void PSScavenge::set_young_generation_boundary(HeapWord* v) {
812 _young_generation_boundary = v;
813 if (UseCompressedOops) {
814 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode((oop)v);
815 }
816 }
817
818 void PSScavenge::initialize() {
819 // Arguments must have been parsed
820
821 if (AlwaysTenure || NeverTenure) {
822 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markWord::max_age + 1,
823 "MaxTenuringThreshold should be 0 or markWord::max_age + 1, but is %d", (int) MaxTenuringThreshold);
824 _tenuring_threshold = MaxTenuringThreshold;
825 } else {
826 // We want to smooth out our startup times for the AdaptiveSizePolicy
827 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
828 MaxTenuringThreshold;
829 }
830
831 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
832 PSYoungGen* young_gen = heap->young_gen();
833 PSOldGen* old_gen = heap->old_gen();
834
835 // Set boundary between young_gen and old_gen
836 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
837 "old above young");
838 set_young_generation_boundary(young_gen->eden_space()->bottom());
839
840 // Initialize ref handling object for scavenging.
841 _span_based_discoverer.set_span(young_gen->reserved());
842 _ref_processor =
843 new ReferenceProcessor(&_span_based_discoverer,
844 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
845 ParallelGCThreads, // mt processing degree
846 true, // mt discovery
847 ParallelGCThreads, // mt discovery degree
848 true, // atomic_discovery
849 NULL, // header provides liveness info
850 false);
851
852 // Cache the cardtable
853 _card_table = heap->card_table();
854
855 _counters = new CollectorCounters("Parallel young collection pauses", 0);
856 }