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