1 /*
2 * Copyright (c) 2002, 2015, 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.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.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 "oops/oop.inline.hpp"
50 #include "runtime/biasedLocking.hpp"
51 #include "runtime/fprofiler.hpp"
52 #include "runtime/handles.inline.hpp"
53 #include "runtime/threadCritical.hpp"
54 #include "runtime/vmThread.hpp"
55 #include "runtime/vm_operations.hpp"
56 #include "services/memoryService.hpp"
57 #include "utilities/stack.inline.hpp"
58
59 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
60 int PSScavenge::_consecutive_skipped_scavenges = 0;
61 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
62 CardTableExtension* PSScavenge::_card_table = NULL;
63 bool PSScavenge::_survivor_overflow = false;
64 uint PSScavenge::_tenuring_threshold = 0;
65 HeapWord* PSScavenge::_young_generation_boundary = NULL;
66 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
67 elapsedTimer PSScavenge::_accumulated_time;
68 STWGCTimer PSScavenge::_gc_timer;
69 ParallelScavengeTracer PSScavenge::_gc_tracer;
70 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack;
71 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack;
72 CollectorCounters* PSScavenge::_counters = NULL;
73
74 // Define before use
75 class PSIsAliveClosure: public BoolObjectClosure {
76 public:
77 bool do_object_b(oop p) {
78 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
79 }
80 };
81
82 PSIsAliveClosure PSScavenge::_is_alive_closure;
83
84 class PSKeepAliveClosure: public OopClosure {
85 protected:
86 MutableSpace* _to_space;
87 PSPromotionManager* _promotion_manager;
88
89 public:
90 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
91 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
92 _to_space = heap->young_gen()->to_space();
93
94 assert(_promotion_manager != NULL, "Sanity");
95 }
96
97 template <class T> void do_oop_work(T* p) {
98 assert (!oopDesc::is_null(*p), "expected non-null ref");
99 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
100 "expected an oop while scanning weak refs");
101
102 // Weak refs may be visited more than once.
103 if (PSScavenge::should_scavenge(p, _to_space)) {
104 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p);
105 }
106 }
107 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
108 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
109 };
110
111 class PSEvacuateFollowersClosure: public VoidClosure {
112 private:
113 PSPromotionManager* _promotion_manager;
114 public:
115 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
116
117 virtual void do_void() {
118 assert(_promotion_manager != NULL, "Sanity");
119 _promotion_manager->drain_stacks(true);
120 guarantee(_promotion_manager->stacks_empty(),
121 "stacks should be empty at this point");
122 }
123 };
124
125 class PSPromotionFailedClosure : public ObjectClosure {
126 virtual void do_object(oop obj) {
127 if (obj->is_forwarded()) {
128 obj->init_mark();
129 }
130 }
131 };
132
133 class PSRefProcTaskProxy: public GCTask {
134 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
135 ProcessTask & _rp_task;
136 uint _work_id;
137 public:
138 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
139 : _rp_task(rp_task),
140 _work_id(work_id)
141 { }
142
143 private:
144 virtual char* name() { return (char *)"Process referents by policy in parallel"; }
145 virtual void do_it(GCTaskManager* manager, uint which);
146 };
147
148 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
149 {
150 PSPromotionManager* promotion_manager =
151 PSPromotionManager::gc_thread_promotion_manager(which);
152 assert(promotion_manager != NULL, "sanity check");
153 PSKeepAliveClosure keep_alive(promotion_manager);
154 PSEvacuateFollowersClosure evac_followers(promotion_manager);
155 PSIsAliveClosure is_alive;
156 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
157 }
158
159 class PSRefEnqueueTaskProxy: public GCTask {
160 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
161 EnqueueTask& _enq_task;
162 uint _work_id;
163
164 public:
165 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
166 : _enq_task(enq_task),
167 _work_id(work_id)
168 { }
169
170 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
171 virtual void do_it(GCTaskManager* manager, uint which)
172 {
173 _enq_task.work(_work_id);
174 }
175 };
176
177 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
178 virtual void execute(ProcessTask& task);
179 virtual void execute(EnqueueTask& task);
180 };
181
182 void PSRefProcTaskExecutor::execute(ProcessTask& task)
183 {
184 GCTaskQueue* q = GCTaskQueue::create();
185 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
186 for(uint i=0; i < manager->active_workers(); i++) {
187 q->enqueue(new PSRefProcTaskProxy(task, i));
188 }
189 ParallelTaskTerminator terminator(manager->active_workers(),
190 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
191 if (task.marks_oops_alive() && manager->active_workers() > 1) {
192 for (uint j = 0; j < manager->active_workers(); j++) {
193 q->enqueue(new StealTask(&terminator));
194 }
195 }
196 manager->execute_and_wait(q);
197 }
198
199
200 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
201 {
202 GCTaskQueue* q = GCTaskQueue::create();
203 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
204 for(uint i=0; i < manager->active_workers(); i++) {
205 q->enqueue(new PSRefEnqueueTaskProxy(task, i));
206 }
207 manager->execute_and_wait(q);
208 }
209
210 // This method contains all heap specific policy for invoking scavenge.
211 // PSScavenge::invoke_no_policy() will do nothing but attempt to
212 // scavenge. It will not clean up after failed promotions, bail out if
213 // we've exceeded policy time limits, or any other special behavior.
214 // All such policy should be placed here.
215 //
216 // Note that this method should only be called from the vm_thread while
217 // at a safepoint!
218 bool PSScavenge::invoke() {
219 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
220 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
221 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
222
223 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap();
224 PSAdaptiveSizePolicy* policy = heap->size_policy();
225 IsGCActiveMark mark;
226
227 const bool scavenge_done = PSScavenge::invoke_no_policy();
228 const bool need_full_gc = !scavenge_done ||
229 policy->should_full_GC(heap->old_gen()->free_in_bytes());
230 bool full_gc_done = false;
231
232 if (UsePerfData) {
233 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
234 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
235 counters->update_full_follows_scavenge(ffs_val);
236 }
237
238 if (need_full_gc) {
239 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
240 CollectorPolicy* cp = heap->collector_policy();
241 const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
242
243 if (UseParallelOldGC) {
244 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
245 } else {
246 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
247 }
248 }
249
250 return full_gc_done;
251 }
252
253 // This method contains no policy. You should probably
254 // be calling invoke() instead.
255 bool PSScavenge::invoke_no_policy() {
256 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
257 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
258
259 assert(_preserved_mark_stack.is_empty(), "should be empty");
260 assert(_preserved_oop_stack.is_empty(), "should be empty");
261
262 _gc_timer.register_gc_start();
263
264 TimeStamp scavenge_entry;
265 TimeStamp scavenge_midpoint;
266 TimeStamp scavenge_exit;
267
268 scavenge_entry.update();
269
270 if (GC_locker::check_active_before_gc()) {
271 return false;
272 }
273
274 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
275 GCCause::Cause gc_cause = heap->gc_cause();
276
277 // Check for potential problems.
278 if (!should_attempt_scavenge()) {
279 return false;
280 }
281
282 GCIdMark gc_id_mark;
283 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
284
285 bool promotion_failure_occurred = false;
286
287 PSYoungGen* young_gen = heap->young_gen();
288 PSOldGen* old_gen = heap->old_gen();
289 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
290
291 heap->increment_total_collections();
292
293 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
294
295 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
296 // Gather the feedback data for eden occupancy.
297 young_gen->eden_space()->accumulate_statistics();
298 }
299
300 heap->print_heap_before_gc();
301 heap->trace_heap_before_gc(&_gc_tracer);
302
303 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
304 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
305
306 size_t prev_used = heap->used();
307
308 // Fill in TLABs
309 heap->accumulate_statistics_all_tlabs();
310 heap->ensure_parsability(true); // retire TLABs
311
312 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
313 HandleMark hm; // Discard invalid handles created during verification
314 Universe::verify(" VerifyBeforeGC:");
315 }
316
317 {
318 ResourceMark rm;
319 HandleMark hm;
320
321 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
322 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
323 TraceCollectorStats tcs(counters());
324 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
325
326 if (TraceYoungGenTime) accumulated_time()->start();
327
328 // Let the size policy know we're starting
329 size_policy->minor_collection_begin();
330
331 // Verify the object start arrays.
332 if (VerifyObjectStartArray &&
333 VerifyBeforeGC) {
334 old_gen->verify_object_start_array();
335 }
336
337 // Verify no unmarked old->young roots
338 if (VerifyRememberedSets) {
339 CardTableExtension::verify_all_young_refs_imprecise();
340 }
341
342 assert(young_gen->to_space()->is_empty(),
343 "Attempt to scavenge with live objects in to_space");
344 young_gen->to_space()->clear(SpaceDecorator::Mangle);
345
346 save_to_space_top_before_gc();
347
348 #if defined(COMPILER2) || INCLUDE_JVMCI
349 DerivedPointerTable::clear();
350 #endif
351
352 reference_processor()->enable_discovery();
353 reference_processor()->setup_policy(false);
354
355 // We track how much was promoted to the next generation for
356 // the AdaptiveSizePolicy.
357 size_t old_gen_used_before = old_gen->used_in_bytes();
358
359 // For PrintGCDetails
360 size_t young_gen_used_before = young_gen->used_in_bytes();
361
362 // Reset our survivor overflow.
363 set_survivor_overflow(false);
364
365 // We need to save the old top values before
366 // creating the promotion_manager. We pass the top
367 // values to the card_table, to prevent it from
368 // straying into the promotion labs.
369 HeapWord* old_top = old_gen->object_space()->top();
370
371 // Release all previously held resources
372 gc_task_manager()->release_all_resources();
373
374 // Set the number of GC threads to be used in this collection
375 gc_task_manager()->set_active_gang();
376 gc_task_manager()->task_idle_workers();
377 // Get the active number of workers here and use that value
378 // throughout the methods.
379 uint active_workers = gc_task_manager()->active_workers();
380
381 PSPromotionManager::pre_scavenge();
382
383 // We'll use the promotion manager again later.
384 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
385 {
386 GCTraceTime tm("Scavenge", false, false, &_gc_timer);
387 ParallelScavengeHeap::ParStrongRootsScope psrs;
388
389 GCTaskQueue* q = GCTaskQueue::create();
390
391 if (!old_gen->object_space()->is_empty()) {
392 // There are only old-to-young pointers if there are objects
393 // in the old gen.
394 uint stripe_total = active_workers;
395 for(uint i=0; i < stripe_total; i++) {
396 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
397 }
398 }
399
400 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
401 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
402 // We scan the thread roots in parallel
403 Threads::create_thread_roots_tasks(q);
404 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
405 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
406 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
407 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
408 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data));
409 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
410 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
411
412 ParallelTaskTerminator terminator(
413 active_workers,
414 (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
415 if (active_workers > 1) {
416 for (uint j = 0; j < active_workers; j++) {
417 q->enqueue(new StealTask(&terminator));
418 }
419 }
420
421 gc_task_manager()->execute_and_wait(q);
422 }
423
424 scavenge_midpoint.update();
425
426 // Process reference objects discovered during scavenge
427 {
428 GCTraceTime tm("References", false, false, &_gc_timer);
429
430 reference_processor()->setup_policy(false); // not always_clear
431 reference_processor()->set_active_mt_degree(active_workers);
432 PSKeepAliveClosure keep_alive(promotion_manager);
433 PSEvacuateFollowersClosure evac_followers(promotion_manager);
434 ReferenceProcessorStats stats;
435 if (reference_processor()->processing_is_mt()) {
436 PSRefProcTaskExecutor task_executor;
437 stats = reference_processor()->process_discovered_references(
438 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
439 &_gc_timer);
440 } else {
441 stats = reference_processor()->process_discovered_references(
442 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer);
443 }
444
445 _gc_tracer.report_gc_reference_stats(stats);
446
447 // Enqueue reference objects discovered during scavenge.
448 if (reference_processor()->processing_is_mt()) {
449 PSRefProcTaskExecutor task_executor;
450 reference_processor()->enqueue_discovered_references(&task_executor);
451 } else {
452 reference_processor()->enqueue_discovered_references(NULL);
453 }
454 }
455
456 {
457 GCTraceTime tm("StringTable", false, false, &_gc_timer);
458 // Unlink any dead interned Strings and process the remaining live ones.
459 PSScavengeRootsClosure root_closure(promotion_manager);
460 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
461 }
462
463 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
464 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
465 if (promotion_failure_occurred) {
466 clean_up_failed_promotion();
467 if (PrintGC) {
468 gclog_or_tty->print("--");
469 }
470 }
471
472 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
473
474 // Let the size policy know we're done. Note that we count promotion
475 // failure cleanup time as part of the collection (otherwise, we're
476 // implicitly saying it's mutator time).
477 size_policy->minor_collection_end(gc_cause);
478
479 if (!promotion_failure_occurred) {
480 // Swap the survivor spaces.
481 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
482 young_gen->from_space()->clear(SpaceDecorator::Mangle);
483 young_gen->swap_spaces();
484
485 size_t survived = young_gen->from_space()->used_in_bytes();
486 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
487 size_policy->update_averages(_survivor_overflow, survived, promoted);
488
489 // A successful scavenge should restart the GC time limit count which is
490 // for full GC's.
491 size_policy->reset_gc_overhead_limit_count();
492 if (UseAdaptiveSizePolicy) {
493 // Calculate the new survivor size and tenuring threshold
494
495 if (PrintAdaptiveSizePolicy) {
496 gclog_or_tty->print("AdaptiveSizeStart: ");
497 gclog_or_tty->stamp();
498 gclog_or_tty->print_cr(" collection: %d ",
499 heap->total_collections());
500
501 if (Verbose) {
502 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
503 " young_gen_capacity: " SIZE_FORMAT,
504 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
505 }
506 }
507
508
509 if (UsePerfData) {
510 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
511 counters->update_old_eden_size(
512 size_policy->calculated_eden_size_in_bytes());
513 counters->update_old_promo_size(
514 size_policy->calculated_promo_size_in_bytes());
515 counters->update_old_capacity(old_gen->capacity_in_bytes());
516 counters->update_young_capacity(young_gen->capacity_in_bytes());
517 counters->update_survived(survived);
518 counters->update_promoted(promoted);
519 counters->update_survivor_overflowed(_survivor_overflow);
520 }
521
522 size_t max_young_size = young_gen->max_size();
523
524 // Deciding a free ratio in the young generation is tricky, so if
525 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
526 // that the old generation size may have been limited because of them) we
527 // should then limit our young generation size using NewRatio to have it
528 // follow the old generation size.
529 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
530 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
531 }
532
533 size_t survivor_limit =
534 size_policy->max_survivor_size(max_young_size);
535 _tenuring_threshold =
536 size_policy->compute_survivor_space_size_and_threshold(
537 _survivor_overflow,
538 _tenuring_threshold,
539 survivor_limit);
540
541 if (PrintTenuringDistribution) {
542 gclog_or_tty->cr();
543 gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u"
544 " (max threshold " UINTX_FORMAT ")",
545 size_policy->calculated_survivor_size_in_bytes(),
546 _tenuring_threshold, MaxTenuringThreshold);
547 }
548
549 if (UsePerfData) {
550 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
551 counters->update_tenuring_threshold(_tenuring_threshold);
552 counters->update_survivor_size_counters();
553 }
554
555 // Do call at minor collections?
556 // Don't check if the size_policy is ready at this
557 // level. Let the size_policy check that internally.
558 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
559 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) {
560 // Calculate optimal free space amounts
561 assert(young_gen->max_size() >
562 young_gen->from_space()->capacity_in_bytes() +
563 young_gen->to_space()->capacity_in_bytes(),
564 "Sizes of space in young gen are out-of-bounds");
565
566 size_t young_live = young_gen->used_in_bytes();
567 size_t eden_live = young_gen->eden_space()->used_in_bytes();
568 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
569 size_t max_old_gen_size = old_gen->max_gen_size();
570 size_t max_eden_size = max_young_size -
571 young_gen->from_space()->capacity_in_bytes() -
572 young_gen->to_space()->capacity_in_bytes();
573
574 // Used for diagnostics
575 size_policy->clear_generation_free_space_flags();
576
577 size_policy->compute_eden_space_size(young_live,
578 eden_live,
579 cur_eden,
580 max_eden_size,
581 false /* not full gc*/);
582
583 size_policy->check_gc_overhead_limit(young_live,
584 eden_live,
585 max_old_gen_size,
586 max_eden_size,
587 false /* not full gc*/,
588 gc_cause,
589 heap->collector_policy());
590
591 size_policy->decay_supplemental_growth(false /* not full gc*/);
592 }
593 // Resize the young generation at every collection
594 // even if new sizes have not been calculated. This is
595 // to allow resizes that may have been inhibited by the
596 // relative location of the "to" and "from" spaces.
597
598 // Resizing the old gen at young collections can cause increases
599 // that don't feed back to the generation sizing policy until
600 // a full collection. Don't resize the old gen here.
601
602 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
603 size_policy->calculated_survivor_size_in_bytes());
604
605 if (PrintAdaptiveSizePolicy) {
606 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
607 heap->total_collections());
608 }
609 }
610
611 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
612 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
613 // Also update() will case adaptive NUMA chunk resizing.
614 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
615 young_gen->eden_space()->update();
616
617 heap->gc_policy_counters()->update_counters();
618
619 heap->resize_all_tlabs();
620
621 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
622 }
623
624 #if defined(COMPILER2) || INCLUDE_JVMCI
625 DerivedPointerTable::update_pointers();
626 #endif
627
628 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
629
630 {
631 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer);
632
633 CodeCache::prune_scavenge_root_nmethods();
634 }
635
636 // Re-verify object start arrays
637 if (VerifyObjectStartArray &&
638 VerifyAfterGC) {
639 old_gen->verify_object_start_array();
640 }
641
642 // Verify all old -> young cards are now precise
643 if (VerifyRememberedSets) {
644 // Precise verification will give false positives. Until this is fixed,
645 // use imprecise verification.
646 // CardTableExtension::verify_all_young_refs_precise();
647 CardTableExtension::verify_all_young_refs_imprecise();
648 }
649
650 if (TraceYoungGenTime) accumulated_time()->stop();
651
652 if (PrintGC) {
653 if (PrintGCDetails) {
654 // Don't print a GC timestamp here. This is after the GC so
655 // would be confusing.
656 young_gen->print_used_change(young_gen_used_before);
657 }
658 heap->print_heap_change(prev_used);
659 }
660
661 // Track memory usage and detect low memory
662 MemoryService::track_memory_usage();
663 heap->update_counters();
664
665 gc_task_manager()->release_idle_workers();
666 }
667
668 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
669 HandleMark hm; // Discard invalid handles created during verification
670 Universe::verify(" VerifyAfterGC:");
671 }
672
673 heap->print_heap_after_gc();
674 heap->trace_heap_after_gc(&_gc_tracer);
675
676 scavenge_exit.update();
677
678 if (PrintGCTaskTimeStamps) {
679 tty->print_cr("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
680 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
681 scavenge_exit.ticks());
682 gc_task_manager()->print_task_time_stamps();
683 }
684
685 #ifdef TRACESPINNING
686 ParallelTaskTerminator::print_termination_counts();
687 #endif
688
689
690 _gc_timer.register_gc_end();
691
692 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
693
694 return !promotion_failure_occurred;
695 }
696
697 // This method iterates over all objects in the young generation,
698 // unforwarding markOops. It then restores any preserved mark oops,
699 // and clears the _preserved_mark_stack.
700 void PSScavenge::clean_up_failed_promotion() {
701 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
702 PSYoungGen* young_gen = heap->young_gen();
703
704 {
705 ResourceMark rm;
706
707 // Unforward all pointers in the young gen.
708 PSPromotionFailedClosure unforward_closure;
709 young_gen->object_iterate(&unforward_closure);
710
711 if (PrintGC && Verbose) {
712 gclog_or_tty->print_cr("Restoring " SIZE_FORMAT " marks", _preserved_oop_stack.size());
713 }
714
715 // Restore any saved marks.
716 while (!_preserved_oop_stack.is_empty()) {
717 oop obj = _preserved_oop_stack.pop();
718 markOop mark = _preserved_mark_stack.pop();
719 obj->set_mark(mark);
720 }
721
722 // Clear the preserved mark and oop stack caches.
723 _preserved_mark_stack.clear(true);
724 _preserved_oop_stack.clear(true);
725 }
726
727 // Reset the PromotionFailureALot counters.
728 NOT_PRODUCT(heap->reset_promotion_should_fail();)
729 }
730
731 // This method is called whenever an attempt to promote an object
732 // fails. Some markOops will need preservation, some will not. Note
733 // that the entire eden is traversed after a failed promotion, with
734 // all forwarded headers replaced by the default markOop. This means
735 // it is not necessary to preserve most markOops.
736 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
737 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
738 // Should use per-worker private stacks here rather than
739 // locking a common pair of stacks.
740 ThreadCritical tc;
741 _preserved_oop_stack.push(obj);
742 _preserved_mark_stack.push(obj_mark);
743 }
744 }
745
746 bool PSScavenge::should_attempt_scavenge() {
747 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
748 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
749
750 if (UsePerfData) {
751 counters->update_scavenge_skipped(not_skipped);
752 }
753
754 PSYoungGen* young_gen = heap->young_gen();
755 PSOldGen* old_gen = heap->old_gen();
756
757 // Do not attempt to promote unless to_space is empty
758 if (!young_gen->to_space()->is_empty()) {
759 _consecutive_skipped_scavenges++;
760 if (UsePerfData) {
761 counters->update_scavenge_skipped(to_space_not_empty);
762 }
763 return false;
764 }
765
766 // Test to see if the scavenge will likely fail.
767 PSAdaptiveSizePolicy* policy = heap->size_policy();
768
769 // A similar test is done in the policy's should_full_GC(). If this is
770 // changed, decide if that test should also be changed.
771 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
772 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
773 bool result = promotion_estimate < old_gen->free_in_bytes();
774
775 if (PrintGCDetails && Verbose) {
776 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: ");
777 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
778 " padded_average_promoted " SIZE_FORMAT
779 " free in old gen " SIZE_FORMAT,
780 (size_t) policy->average_promoted_in_bytes(),
781 (size_t) policy->padded_average_promoted_in_bytes(),
782 old_gen->free_in_bytes());
783 if (young_gen->used_in_bytes() <
784 (size_t) policy->padded_average_promoted_in_bytes()) {
785 gclog_or_tty->print_cr(" padded_promoted_average is greater"
786 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
787 }
788 }
789
790 if (result) {
791 _consecutive_skipped_scavenges = 0;
792 } else {
793 _consecutive_skipped_scavenges++;
794 if (UsePerfData) {
795 counters->update_scavenge_skipped(promoted_too_large);
796 }
797 }
798 return result;
799 }
800
801 // Used to add tasks
802 GCTaskManager* const PSScavenge::gc_task_manager() {
803 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
804 "shouldn't return NULL");
805 return ParallelScavengeHeap::gc_task_manager();
806 }
807
808 void PSScavenge::initialize() {
809 // Arguments must have been parsed
810
811 if (AlwaysTenure || NeverTenure) {
812 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1,
813 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold);
814 _tenuring_threshold = MaxTenuringThreshold;
815 } else {
816 // We want to smooth out our startup times for the AdaptiveSizePolicy
817 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
818 MaxTenuringThreshold;
819 }
820
821 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
822 PSYoungGen* young_gen = heap->young_gen();
823 PSOldGen* old_gen = heap->old_gen();
824
825 // Set boundary between young_gen and old_gen
826 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
827 "old above young");
828 set_young_generation_boundary(young_gen->eden_space()->bottom());
829
830 // Initialize ref handling object for scavenging.
831 MemRegion mr = young_gen->reserved();
832
833 _ref_processor =
834 new ReferenceProcessor(mr, // span
835 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
836 ParallelGCThreads, // mt processing degree
837 true, // mt discovery
838 ParallelGCThreads, // mt discovery degree
839 true, // atomic_discovery
840 NULL); // header provides liveness info
841
842 // Cache the cardtable
843 _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set());
844
845 _counters = new CollectorCounters("PSScavenge", 0);
846 }