1 /*
2 * Copyright (c) 2002, 2017, 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 CollectorCounters* PSScavenge::_counters = NULL;
72
73 // Define before use
74 class PSIsAliveClosure: public BoolObjectClosure {
75 public:
76 bool do_object_b(oop p) {
77 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
78 }
79 };
80
81 PSIsAliveClosure PSScavenge::_is_alive_closure;
82
83 class PSKeepAliveClosure: public OopClosure {
84 protected:
85 MutableSpace* _to_space;
86 PSPromotionManager* _promotion_manager;
87
88 public:
89 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
90 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
91 _to_space = heap->young_gen()->to_space();
92
93 assert(_promotion_manager != NULL, "Sanity");
94 }
95
96 template <class T> void do_oop_work(T* p) {
97 assert (!oopDesc::is_null(*p), "expected non-null ref");
98 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
99 "expected an oop while scanning weak refs");
100
101 // Weak refs may be visited more than once.
102 if (PSScavenge::should_scavenge(p, _to_space)) {
103 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p);
104 }
105 }
106 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
107 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
108 };
109
110 class PSEvacuateFollowersClosure: public VoidClosure {
111 private:
112 PSPromotionManager* _promotion_manager;
113 public:
114 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
115
116 virtual void do_void() {
117 assert(_promotion_manager != NULL, "Sanity");
118 _promotion_manager->drain_stacks(true);
119 guarantee(_promotion_manager->stacks_empty(),
120 "stacks should be empty at this point");
121 }
122 };
123
124 class PSRefProcTaskProxy: public GCTask {
125 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
126 ProcessTask & _rp_task;
127 uint _work_id;
128 public:
129 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
130 : _rp_task(rp_task),
131 _work_id(work_id)
132 { }
133
134 private:
135 virtual char* name() { return (char *)"Process referents by policy in parallel"; }
136 virtual void do_it(GCTaskManager* manager, uint which);
137 };
138
139 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
140 {
141 PSPromotionManager* promotion_manager =
142 PSPromotionManager::gc_thread_promotion_manager(which);
143 assert(promotion_manager != NULL, "sanity check");
144 PSKeepAliveClosure keep_alive(promotion_manager);
145 PSEvacuateFollowersClosure evac_followers(promotion_manager);
146 PSIsAliveClosure is_alive;
147 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
148 }
149
150 class PSRefEnqueueTaskProxy: public GCTask {
151 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
152 EnqueueTask& _enq_task;
153 uint _work_id;
154
155 public:
156 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
157 : _enq_task(enq_task),
158 _work_id(work_id)
159 { }
160
161 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
162 virtual void do_it(GCTaskManager* manager, uint which)
163 {
164 _enq_task.work(_work_id);
165 }
166 };
167
168 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
169 virtual void execute(ProcessTask& task);
170 virtual void execute(EnqueueTask& task);
171 };
172
173 void PSRefProcTaskExecutor::execute(ProcessTask& task)
174 {
175 GCTaskQueue* q = GCTaskQueue::create();
176 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
177 for(uint i=0; i < manager->active_workers(); i++) {
178 q->enqueue(new PSRefProcTaskProxy(task, i));
179 }
180 ParallelTaskTerminator terminator(manager->active_workers(),
181 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
182 if (task.marks_oops_alive() && manager->active_workers() > 1) {
183 for (uint j = 0; j < manager->active_workers(); j++) {
184 q->enqueue(new StealTask(&terminator));
185 }
186 }
187 manager->execute_and_wait(q);
188 }
189
190
191 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
192 {
193 GCTaskQueue* q = GCTaskQueue::create();
194 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
195 for(uint i=0; i < manager->active_workers(); i++) {
196 q->enqueue(new PSRefEnqueueTaskProxy(task, i));
197 }
198 manager->execute_and_wait(q);
199 }
200
201 // This method contains all heap specific policy for invoking scavenge.
202 // PSScavenge::invoke_no_policy() will do nothing but attempt to
203 // scavenge. It will not clean up after failed promotions, bail out if
204 // we've exceeded policy time limits, or any other special behavior.
205 // All such policy should be placed here.
206 //
207 // Note that this method should only be called from the vm_thread while
208 // at a safepoint!
209 bool PSScavenge::invoke() {
210 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
211 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
212 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
213
214 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap();
215 PSAdaptiveSizePolicy* policy = heap->size_policy();
216 IsGCActiveMark mark;
217
218 const bool scavenge_done = PSScavenge::invoke_no_policy();
219 const bool need_full_gc = !scavenge_done ||
220 policy->should_full_GC(heap->old_gen()->free_in_bytes());
221 bool full_gc_done = false;
222
223 if (UsePerfData) {
224 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
225 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
226 counters->update_full_follows_scavenge(ffs_val);
227 }
228
229 if (need_full_gc) {
230 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
231 CollectorPolicy* cp = heap->collector_policy();
232 const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
233
234 if (UseParallelOldGC) {
235 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
236 } else {
237 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
238 }
239 }
240
241 return full_gc_done;
242 }
243
244 // This method contains no policy. You should probably
245 // be calling invoke() instead.
246 bool PSScavenge::invoke_no_policy() {
247 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
248 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
249
250 _gc_timer.register_gc_start();
251
252 TimeStamp scavenge_entry;
253 TimeStamp scavenge_midpoint;
254 TimeStamp scavenge_exit;
255
256 scavenge_entry.update();
257
258 if (GCLocker::check_active_before_gc()) {
259 return false;
260 }
261
262 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
263 GCCause::Cause gc_cause = heap->gc_cause();
264
265 // Check for potential problems.
266 if (!should_attempt_scavenge()) {
267 return false;
268 }
269
270 GCIdMark gc_id_mark;
271 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
272
273 bool promotion_failure_occurred = false;
274
275 PSYoungGen* young_gen = heap->young_gen();
276 PSOldGen* old_gen = heap->old_gen();
277 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
278
279 heap->increment_total_collections();
280
281 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) {
282 // Gather the feedback data for eden occupancy.
283 young_gen->eden_space()->accumulate_statistics();
284 }
285
286 heap->print_heap_before_gc();
287 heap->trace_heap_before_gc(&_gc_tracer);
288
289 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
290 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
291
292 // Fill in TLABs
293 heap->accumulate_statistics_all_tlabs();
294 heap->ensure_parsability(true); // retire TLABs
295
296 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
297 HandleMark hm; // Discard invalid handles created during verification
298 Universe::verify("Before GC");
299 }
300
301 {
302 ResourceMark rm;
303 HandleMark hm;
304
305 GCTraceCPUTime tcpu;
306 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true);
307 TraceCollectorStats tcs(counters());
308 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
309
310 if (TraceYoungGenTime) accumulated_time()->start();
311
312 // Let the size policy know we're starting
313 size_policy->minor_collection_begin();
314
315 // Verify the object start arrays.
316 if (VerifyObjectStartArray &&
317 VerifyBeforeGC) {
318 old_gen->verify_object_start_array();
319 }
320
321 // Verify no unmarked old->young roots
322 if (VerifyRememberedSets) {
323 CardTableExtension::verify_all_young_refs_imprecise();
324 }
325
326 assert(young_gen->to_space()->is_empty(),
327 "Attempt to scavenge with live objects in to_space");
328 young_gen->to_space()->clear(SpaceDecorator::Mangle);
329
330 save_to_space_top_before_gc();
331
332 #if defined(COMPILER2) || INCLUDE_JVMCI
333 DerivedPointerTable::clear();
334 #endif
335
336 reference_processor()->enable_discovery();
337 reference_processor()->setup_policy(false);
338
339 PreGCValues pre_gc_values(heap);
340
341 // Reset our survivor overflow.
342 set_survivor_overflow(false);
343
344 // We need to save the old top values before
345 // creating the promotion_manager. We pass the top
346 // values to the card_table, to prevent it from
347 // straying into the promotion labs.
348 HeapWord* old_top = old_gen->object_space()->top();
349
350 // Release all previously held resources
351 gc_task_manager()->release_all_resources();
352
353 // Set the number of GC threads to be used in this collection
354 gc_task_manager()->set_active_gang();
355 gc_task_manager()->task_idle_workers();
356 // Get the active number of workers here and use that value
357 // throughout the methods.
358 uint active_workers = gc_task_manager()->active_workers();
359
360 PSPromotionManager::pre_scavenge();
361
362 // We'll use the promotion manager again later.
363 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
364 {
365 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer);
366 ParallelScavengeHeap::ParStrongRootsScope psrs;
367
368 GCTaskQueue* q = GCTaskQueue::create();
369
370 if (!old_gen->object_space()->is_empty()) {
371 // There are only old-to-young pointers if there are objects
372 // in the old gen.
373 uint stripe_total = active_workers;
374 for(uint i=0; i < stripe_total; i++) {
375 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
376 }
377 }
378
379 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
380 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
381 // We scan the thread roots in parallel
382 Threads::create_thread_roots_tasks(q);
383 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
384 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
385 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
386 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
387 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data));
388 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
389 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
390
391 ParallelTaskTerminator terminator(
392 active_workers,
393 (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
394 // If active_workers can exceed 1, add a StrealTask.
395 // PSPromotionManager::drain_stacks_depth() does not fully drain its
396 // stacks and expects a StealTask to complete the draining if
397 // ParallelGCThreads is > 1.
398 if (gc_task_manager()->workers() > 1) {
399 for (uint j = 0; j < active_workers; j++) {
400 q->enqueue(new StealTask(&terminator));
401 }
402 }
403
404 gc_task_manager()->execute_and_wait(q);
405 }
406
407 scavenge_midpoint.update();
408
409 // Process reference objects discovered during scavenge
410 {
411 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
412
413 reference_processor()->setup_policy(false); // not always_clear
414 reference_processor()->set_active_mt_degree(active_workers);
415 PSKeepAliveClosure keep_alive(promotion_manager);
416 PSEvacuateFollowersClosure evac_followers(promotion_manager);
417 ReferenceProcessorStats stats;
418 ReferenceProcessorPhaseTimes pt(&_gc_timer,
419 reference_processor()->num_q(),
420 reference_processor()->processing_is_mt());
421 if (reference_processor()->processing_is_mt()) {
422 PSRefProcTaskExecutor task_executor;
423 stats = reference_processor()->process_discovered_references(
424 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
425 &pt);
426 } else {
427 stats = reference_processor()->process_discovered_references(
428 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt);
429 }
430
431 _gc_tracer.report_gc_reference_stats(stats);
432 pt.print_all_references();
433
434 // Enqueue reference objects discovered during scavenge.
435 if (reference_processor()->processing_is_mt()) {
436 PSRefProcTaskExecutor task_executor;
437 reference_processor()->enqueue_discovered_references(&task_executor, &pt);
438 } else {
439 reference_processor()->enqueue_discovered_references(NULL, &pt);
440 }
441
442 pt.print_enqueue_phase();
443 }
444
445 {
446 GCTraceTime(Debug, gc, phases) tm("Scrub String Table", &_gc_timer);
447 // Unlink any dead interned Strings and process the remaining live ones.
448 PSScavengeRootsClosure root_closure(promotion_manager);
449 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
450 }
451
452 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
453 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
454 if (promotion_failure_occurred) {
455 clean_up_failed_promotion();
456 log_info(gc, promotion)("Promotion failed");
457 }
458
459 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
460
461 // Let the size policy know we're done. Note that we count promotion
462 // failure cleanup time as part of the collection (otherwise, we're
463 // implicitly saying it's mutator time).
464 size_policy->minor_collection_end(gc_cause);
465
466 if (!promotion_failure_occurred) {
467 // Swap the survivor spaces.
468 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
469 young_gen->from_space()->clear(SpaceDecorator::Mangle);
470 young_gen->swap_spaces();
471
472 size_t survived = young_gen->from_space()->used_in_bytes();
473 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used();
474 size_policy->update_averages(_survivor_overflow, survived, promoted);
475
476 // A successful scavenge should restart the GC time limit count which is
477 // for full GC's.
478 size_policy->reset_gc_overhead_limit_count();
479 if (UseAdaptiveSizePolicy) {
480 // Calculate the new survivor size and tenuring threshold
481
482 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
483 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
484 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
485
486 if (UsePerfData) {
487 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
488 counters->update_old_eden_size(
489 size_policy->calculated_eden_size_in_bytes());
490 counters->update_old_promo_size(
491 size_policy->calculated_promo_size_in_bytes());
492 counters->update_old_capacity(old_gen->capacity_in_bytes());
493 counters->update_young_capacity(young_gen->capacity_in_bytes());
494 counters->update_survived(survived);
495 counters->update_promoted(promoted);
496 counters->update_survivor_overflowed(_survivor_overflow);
497 }
498
499 size_t max_young_size = young_gen->max_size();
500
501 // Deciding a free ratio in the young generation is tricky, so if
502 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
503 // that the old generation size may have been limited because of them) we
504 // should then limit our young generation size using NewRatio to have it
505 // follow the old generation size.
506 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
507 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
508 }
509
510 size_t survivor_limit =
511 size_policy->max_survivor_size(max_young_size);
512 _tenuring_threshold =
513 size_policy->compute_survivor_space_size_and_threshold(
514 _survivor_overflow,
515 _tenuring_threshold,
516 survivor_limit);
517
518 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")",
519 size_policy->calculated_survivor_size_in_bytes(),
520 _tenuring_threshold, MaxTenuringThreshold);
521
522 if (UsePerfData) {
523 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
524 counters->update_tenuring_threshold(_tenuring_threshold);
525 counters->update_survivor_size_counters();
526 }
527
528 // Do call at minor collections?
529 // Don't check if the size_policy is ready at this
530 // level. Let the size_policy check that internally.
531 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
532 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) {
533 // Calculate optimal free space amounts
534 assert(young_gen->max_size() >
535 young_gen->from_space()->capacity_in_bytes() +
536 young_gen->to_space()->capacity_in_bytes(),
537 "Sizes of space in young gen are out-of-bounds");
538
539 size_t young_live = young_gen->used_in_bytes();
540 size_t eden_live = young_gen->eden_space()->used_in_bytes();
541 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
542 size_t max_old_gen_size = old_gen->max_gen_size();
543 size_t max_eden_size = max_young_size -
544 young_gen->from_space()->capacity_in_bytes() -
545 young_gen->to_space()->capacity_in_bytes();
546
547 // Used for diagnostics
548 size_policy->clear_generation_free_space_flags();
549
550 size_policy->compute_eden_space_size(young_live,
551 eden_live,
552 cur_eden,
553 max_eden_size,
554 false /* not full gc*/);
555
556 size_policy->check_gc_overhead_limit(young_live,
557 eden_live,
558 max_old_gen_size,
559 max_eden_size,
560 false /* not full gc*/,
561 gc_cause,
562 heap->collector_policy());
563
564 size_policy->decay_supplemental_growth(false /* not full gc*/);
565 }
566 // Resize the young generation at every collection
567 // even if new sizes have not been calculated. This is
568 // to allow resizes that may have been inhibited by the
569 // relative location of the "to" and "from" spaces.
570
571 // Resizing the old gen at young collections can cause increases
572 // that don't feed back to the generation sizing policy until
573 // a full collection. Don't resize the old gen here.
574
575 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
576 size_policy->calculated_survivor_size_in_bytes());
577
578 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
579 }
580
581 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
582 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
583 // Also update() will case adaptive NUMA chunk resizing.
584 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
585 young_gen->eden_space()->update();
586
587 heap->gc_policy_counters()->update_counters();
588
589 heap->resize_all_tlabs();
590
591 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
592 }
593
594 #if defined(COMPILER2) || INCLUDE_JVMCI
595 DerivedPointerTable::update_pointers();
596 #endif
597
598 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
599
600 // Re-verify object start arrays
601 if (VerifyObjectStartArray &&
602 VerifyAfterGC) {
603 old_gen->verify_object_start_array();
604 }
605
606 // Verify all old -> young cards are now precise
607 if (VerifyRememberedSets) {
608 // Precise verification will give false positives. Until this is fixed,
609 // use imprecise verification.
610 // CardTableExtension::verify_all_young_refs_precise();
611 CardTableExtension::verify_all_young_refs_imprecise();
612 }
613
614 if (TraceYoungGenTime) accumulated_time()->stop();
615
616 young_gen->print_used_change(pre_gc_values.young_gen_used());
617 old_gen->print_used_change(pre_gc_values.old_gen_used());
618 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
619
620 // Track memory usage and detect low memory
621 MemoryService::track_memory_usage();
622 heap->update_counters();
623
624 gc_task_manager()->release_idle_workers();
625 }
626
627 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
628 HandleMark hm; // Discard invalid handles created during verification
629 Universe::verify("After GC");
630 }
631
632 heap->print_heap_after_gc();
633 heap->trace_heap_after_gc(&_gc_tracer);
634
635 scavenge_exit.update();
636
637 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
638 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
639 scavenge_exit.ticks());
640 gc_task_manager()->print_task_time_stamps();
641
642 #ifdef TRACESPINNING
643 ParallelTaskTerminator::print_termination_counts();
644 #endif
645
646 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
647
648 _gc_timer.register_gc_end();
649
650 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
651
652 return !promotion_failure_occurred;
653 }
654
655 // This method iterates over all objects in the young generation,
656 // removing all forwarding references. It then restores any preserved marks.
657 void PSScavenge::clean_up_failed_promotion() {
658 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
659 PSYoungGen* young_gen = heap->young_gen();
660
661 RemoveForwardedPointerClosure remove_fwd_ptr_closure;
662 young_gen->object_iterate(&remove_fwd_ptr_closure);
663
664 PSPromotionManager::restore_preserved_marks();
665
666 // Reset the PromotionFailureALot counters.
667 NOT_PRODUCT(heap->reset_promotion_should_fail();)
668 }
669
670 bool PSScavenge::should_attempt_scavenge() {
671 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
672 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
673
674 if (UsePerfData) {
675 counters->update_scavenge_skipped(not_skipped);
676 }
677
678 PSYoungGen* young_gen = heap->young_gen();
679 PSOldGen* old_gen = heap->old_gen();
680
681 // Do not attempt to promote unless to_space is empty
682 if (!young_gen->to_space()->is_empty()) {
683 _consecutive_skipped_scavenges++;
684 if (UsePerfData) {
685 counters->update_scavenge_skipped(to_space_not_empty);
686 }
687 return false;
688 }
689
690 // Test to see if the scavenge will likely fail.
691 PSAdaptiveSizePolicy* policy = heap->size_policy();
692
693 // A similar test is done in the policy's should_full_GC(). If this is
694 // changed, decide if that test should also be changed.
695 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
696 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
697 bool result = promotion_estimate < old_gen->free_in_bytes();
698
699 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT,
700 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(),
701 (size_t) policy->padded_average_promoted_in_bytes(),
702 old_gen->free_in_bytes());
703 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) {
704 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
705 }
706
707 if (result) {
708 _consecutive_skipped_scavenges = 0;
709 } else {
710 _consecutive_skipped_scavenges++;
711 if (UsePerfData) {
712 counters->update_scavenge_skipped(promoted_too_large);
713 }
714 }
715 return result;
716 }
717
718 // Used to add tasks
719 GCTaskManager* const PSScavenge::gc_task_manager() {
720 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
721 "shouldn't return NULL");
722 return ParallelScavengeHeap::gc_task_manager();
723 }
724
725 // Adaptive size policy support. When the young generation/old generation
726 // boundary moves, _young_generation_boundary must be reset
727 void PSScavenge::set_young_generation_boundary(HeapWord* v) {
728 _young_generation_boundary = v;
729 if (UseCompressedOops) {
730 _young_generation_boundary_compressed = (uintptr_t)oopDesc::encode_heap_oop((oop)v);
731 }
732 }
733
734 void PSScavenge::initialize() {
735 // Arguments must have been parsed
736
737 if (AlwaysTenure || NeverTenure) {
738 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1,
739 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold);
740 _tenuring_threshold = MaxTenuringThreshold;
741 } else {
742 // We want to smooth out our startup times for the AdaptiveSizePolicy
743 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
744 MaxTenuringThreshold;
745 }
746
747 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
748 PSYoungGen* young_gen = heap->young_gen();
749 PSOldGen* old_gen = heap->old_gen();
750
751 // Set boundary between young_gen and old_gen
752 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
753 "old above young");
754 set_young_generation_boundary(young_gen->eden_space()->bottom());
755
756 // Initialize ref handling object for scavenging.
757 MemRegion mr = young_gen->reserved();
758
759 _ref_processor =
760 new ReferenceProcessor(mr, // span
761 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
762 ParallelGCThreads, // mt processing degree
763 true, // mt discovery
764 ParallelGCThreads, // mt discovery degree
765 true, // atomic_discovery
766 NULL); // header provides liveness info
767
768 // Cache the cardtable
769 _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set());
770
771 _counters = new CollectorCounters("PSScavenge", 0);
772 }