1
2 /*
3 * Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
30 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
32 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
33 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
34 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
35 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
36 #include "gc_implementation/parallelScavenge/psTasks.hpp"
37 #include "gc_implementation/shared/gcHeapSummary.hpp"
38 #include "gc_implementation/shared/gcTimer.hpp"
39 #include "gc_implementation/shared/gcTrace.hpp"
40 #include "gc_implementation/shared/gcTraceTime.hpp"
41 #include "gc_implementation/shared/isGCActiveMark.hpp"
42 #include "gc_implementation/shared/spaceDecorator.hpp"
43 #include "gc_interface/collectedHeap.inline.hpp"
44 #include "gc_interface/gcCause.hpp"
45 #include "memory/collectorPolicy.hpp"
46 #include "memory/gcLocker.inline.hpp"
47 #include "memory/referencePolicy.hpp"
48 #include "memory/referenceProcessor.hpp"
49 #include "memory/resourceArea.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/oop.psgc.inline.hpp"
52 #include "runtime/biasedLocking.hpp"
53 #include "runtime/fprofiler.hpp"
54 #include "runtime/handles.inline.hpp"
55 #include "runtime/threadCritical.hpp"
56 #include "runtime/vmThread.hpp"
57 #include "runtime/vm_operations.hpp"
58 #include "services/memoryService.hpp"
59 #include "utilities/stack.inline.hpp"
60
61 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
62
63 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
64 int PSScavenge::_consecutive_skipped_scavenges = 0;
65 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
66 CardTableExtension* PSScavenge::_card_table = NULL;
67 bool PSScavenge::_survivor_overflow = false;
68 uint PSScavenge::_tenuring_threshold = 0;
69 HeapWord* PSScavenge::_young_generation_boundary = NULL;
70 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
71 elapsedTimer PSScavenge::_accumulated_time;
72 STWGCTimer PSScavenge::_gc_timer;
73 ParallelScavengeTracer PSScavenge::_gc_tracer;
74 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack;
75 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack;
76 CollectorCounters* PSScavenge::_counters = NULL;
77
78 // Define before use
79 class PSIsAliveClosure: public BoolObjectClosure {
80 public:
81 bool do_object_b(oop p) {
82 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
83 }
84 };
85
86 PSIsAliveClosure PSScavenge::_is_alive_closure;
87
88 class PSKeepAliveClosure: public OopClosure {
89 protected:
90 MutableSpace* _to_space;
91 PSPromotionManager* _promotion_manager;
92
93 public:
94 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
95 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
96 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
97 _to_space = heap->young_gen()->to_space();
98
99 assert(_promotion_manager != NULL, "Sanity");
100 }
101
102 template <class T> void do_oop_work(T* p) {
103 assert (!oopDesc::is_null(*p), "expected non-null ref");
104 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
105 "expected an oop while scanning weak refs");
106
107 // Weak refs may be visited more than once.
108 if (PSScavenge::should_scavenge(p, _to_space)) {
109 PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p);
110 }
111 }
112 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
113 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
114 };
115
116 class PSEvacuateFollowersClosure: public VoidClosure {
117 private:
118 PSPromotionManager* _promotion_manager;
119 public:
120 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
121
122 virtual void do_void() {
123 assert(_promotion_manager != NULL, "Sanity");
124 _promotion_manager->drain_stacks(true);
125 guarantee(_promotion_manager->stacks_empty(),
126 "stacks should be empty at this point");
127 }
128 };
129
130 class PSPromotionFailedClosure : public ObjectClosure {
131 virtual void do_object(oop obj) {
132 if (obj->is_forwarded()) {
133 obj->init_mark();
134 }
135 }
136 };
137
138 class PSRefProcTaskProxy: public GCTask {
139 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
140 ProcessTask & _rp_task;
141 uint _work_id;
142 public:
143 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
144 : _rp_task(rp_task),
145 _work_id(work_id)
146 { }
147
148 private:
149 virtual char* name() { return (char *)"Process referents by policy in parallel"; }
150 virtual void do_it(GCTaskManager* manager, uint which);
151 };
152
153 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
154 {
155 PSPromotionManager* promotion_manager =
156 PSPromotionManager::gc_thread_promotion_manager(which);
157 assert(promotion_manager != NULL, "sanity check");
158 PSKeepAliveClosure keep_alive(promotion_manager);
159 PSEvacuateFollowersClosure evac_followers(promotion_manager);
160 PSIsAliveClosure is_alive;
161 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
162 }
163
164 class PSRefEnqueueTaskProxy: public GCTask {
165 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
166 EnqueueTask& _enq_task;
167 uint _work_id;
168
169 public:
170 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
171 : _enq_task(enq_task),
172 _work_id(work_id)
173 { }
174
175 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
176 virtual void do_it(GCTaskManager* manager, uint which)
177 {
178 _enq_task.work(_work_id);
179 }
180 };
181
182 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
183 virtual void execute(ProcessTask& task);
184 virtual void execute(EnqueueTask& task);
185 };
186
187 void PSRefProcTaskExecutor::execute(ProcessTask& task)
188 {
189 GCTaskQueue* q = GCTaskQueue::create();
190 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
191 for(uint i=0; i < manager->active_workers(); i++) {
192 q->enqueue(new PSRefProcTaskProxy(task, i));
193 }
194 ParallelTaskTerminator terminator(manager->active_workers(),
195 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
196 if (task.marks_oops_alive() && manager->active_workers() > 1) {
197 for (uint j = 0; j < manager->active_workers(); j++) {
198 q->enqueue(new StealTask(&terminator));
199 }
200 }
201 manager->execute_and_wait(q);
202 }
203
204
205 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
206 {
207 GCTaskQueue* q = GCTaskQueue::create();
208 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
209 for(uint i=0; i < manager->active_workers(); i++) {
210 q->enqueue(new PSRefEnqueueTaskProxy(task, i));
211 }
212 manager->execute_and_wait(q);
213 }
214
215 // This method contains all heap specific policy for invoking scavenge.
216 // PSScavenge::invoke_no_policy() will do nothing but attempt to
217 // scavenge. It will not clean up after failed promotions, bail out if
218 // we've exceeded policy time limits, or any other special behavior.
219 // All such policy should be placed here.
220 //
221 // Note that this method should only be called from the vm_thread while
222 // at a safepoint!
223 bool PSScavenge::invoke() {
224 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
225 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
226 assert(!Universe::heap()->is_gc_active(), "not reentrant");
227
228 ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap();
229 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
230
231 PSAdaptiveSizePolicy* policy = heap->size_policy();
232 IsGCActiveMark mark;
233
234 const bool scavenge_done = PSScavenge::invoke_no_policy();
235 const bool need_full_gc = !scavenge_done ||
236 policy->should_full_GC(heap->old_gen()->free_in_bytes());
237 bool full_gc_done = false;
238
239 if (UsePerfData) {
240 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
241 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
242 counters->update_full_follows_scavenge(ffs_val);
243 }
244
245 if (need_full_gc) {
246 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
247 CollectorPolicy* cp = heap->collector_policy();
248 const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
249
250 if (UseParallelOldGC) {
251 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
252 } else {
253 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
254 }
255 }
256
257 return full_gc_done;
258 }
259
260 // This method contains no policy. You should probably
261 // be calling invoke() instead.
262 bool PSScavenge::invoke_no_policy() {
263 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
264 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
265
266 assert(_preserved_mark_stack.is_empty(), "should be empty");
267 assert(_preserved_oop_stack.is_empty(), "should be empty");
268
269 _gc_timer.register_gc_start();
270
271 TimeStamp scavenge_entry;
272 TimeStamp scavenge_midpoint;
273 TimeStamp scavenge_exit;
274
275 scavenge_entry.update();
276
277 if (GC_locker::check_active_before_gc()) {
278 return false;
279 }
280
281 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
282 GCCause::Cause gc_cause = heap->gc_cause();
283 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
284
285 // Check for potential problems.
286 if (!should_attempt_scavenge()) {
287 return false;
288 }
289
290 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
291
292 bool promotion_failure_occurred = false;
293
294 PSYoungGen* young_gen = heap->young_gen();
295 PSOldGen* old_gen = heap->old_gen();
296 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
297
298 heap->increment_total_collections();
299
300 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
301
302 if ((gc_cause != GCCause::_java_lang_system_gc) ||
303 UseAdaptiveSizePolicyWithSystemGC) {
304 // Gather the feedback data for eden occupancy.
305 young_gen->eden_space()->accumulate_statistics();
306 }
307
308 if (ZapUnusedHeapArea) {
309 // Save information needed to minimize mangling
310 heap->record_gen_tops_before_GC();
311 }
312
313 heap->print_heap_before_gc();
314 heap->trace_heap_before_gc(&_gc_tracer);
315
316 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
317 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
318
319 size_t prev_used = heap->used();
320
321 // Fill in TLABs
322 heap->accumulate_statistics_all_tlabs();
323 heap->ensure_parsability(true); // retire TLABs
324
325 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
326 HandleMark hm; // Discard invalid handles created during verification
327 Universe::verify(" VerifyBeforeGC:");
328 }
329
330 {
331 ResourceMark rm;
332 HandleMark hm;
333
334 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
335 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
336 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer.gc_id());
337 TraceCollectorStats tcs(counters());
338 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
339
340 if (TraceYoungGenTime) accumulated_time()->start();
341
342 // Let the size policy know we're starting
343 size_policy->minor_collection_begin();
344
345 // Verify the object start arrays.
346 if (VerifyObjectStartArray &&
347 VerifyBeforeGC) {
348 old_gen->verify_object_start_array();
349 }
350
351 // Verify no unmarked old->young roots
352 if (VerifyRememberedSets) {
353 CardTableExtension::verify_all_young_refs_imprecise();
354 }
355
356 if (!ScavengeWithObjectsInToSpace) {
357 assert(young_gen->to_space()->is_empty(),
358 "Attempt to scavenge with live objects in to_space");
359 young_gen->to_space()->clear(SpaceDecorator::Mangle);
360 } else if (ZapUnusedHeapArea) {
361 young_gen->to_space()->mangle_unused_area();
362 }
363 save_to_space_top_before_gc();
364
365 COMPILER2_PRESENT(DerivedPointerTable::clear());
366
367 reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
368 reference_processor()->setup_policy(false);
369
370 // We track how much was promoted to the next generation for
371 // the AdaptiveSizePolicy.
372 size_t old_gen_used_before = old_gen->used_in_bytes();
373
374 // For PrintGCDetails
375 size_t young_gen_used_before = young_gen->used_in_bytes();
376
377 // Reset our survivor overflow.
378 set_survivor_overflow(false);
379
380 // We need to save the old top values before
381 // creating the promotion_manager. We pass the top
382 // values to the card_table, to prevent it from
383 // straying into the promotion labs.
384 HeapWord* old_top = old_gen->object_space()->top();
385
386 // Release all previously held resources
387 gc_task_manager()->release_all_resources();
388
389 // Set the number of GC threads to be used in this collection
390 gc_task_manager()->set_active_gang();
391 gc_task_manager()->task_idle_workers();
392 // Get the active number of workers here and use that value
393 // throughout the methods.
394 uint active_workers = gc_task_manager()->active_workers();
395 heap->set_par_threads(active_workers);
396
397 PSPromotionManager::pre_scavenge();
398
399 // We'll use the promotion manager again later.
400 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
401 {
402 GCTraceTime tm("Scavenge", false, false, &_gc_timer, _gc_tracer.gc_id());
403 ParallelScavengeHeap::ParStrongRootsScope psrs;
404
405 GCTaskQueue* q = GCTaskQueue::create();
406
407 if (!old_gen->object_space()->is_empty()) {
408 // There are only old-to-young pointers if there are objects
409 // in the old gen.
410 uint stripe_total = active_workers;
411 for(uint i=0; i < stripe_total; i++) {
412 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
413 }
414 }
415
416 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
417 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
418 // We scan the thread roots in parallel
419 Threads::create_thread_roots_tasks(q);
420 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
421 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
422 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
423 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
424 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data));
425 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
426 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
427
428 ParallelTaskTerminator terminator(
429 active_workers,
430 (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
431 if (active_workers > 1) {
432 for (uint j = 0; j < active_workers; j++) {
433 q->enqueue(new StealTask(&terminator));
434 }
435 }
436
437 gc_task_manager()->execute_and_wait(q);
438 }
439
440 scavenge_midpoint.update();
441
442 // Process reference objects discovered during scavenge
443 {
444 GCTraceTime tm("References", false, false, &_gc_timer, _gc_tracer.gc_id());
445
446 reference_processor()->setup_policy(false); // not always_clear
447 reference_processor()->set_active_mt_degree(active_workers);
448 PSKeepAliveClosure keep_alive(promotion_manager);
449 PSEvacuateFollowersClosure evac_followers(promotion_manager);
450 ReferenceProcessorStats stats;
451 if (reference_processor()->processing_is_mt()) {
452 PSRefProcTaskExecutor task_executor;
453 stats = reference_processor()->process_discovered_references(
454 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
455 &_gc_timer, _gc_tracer.gc_id());
456 } else {
457 stats = reference_processor()->process_discovered_references(
458 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer, _gc_tracer.gc_id());
459 }
460
461 _gc_tracer.report_gc_reference_stats(stats);
462
463 // Enqueue reference objects discovered during scavenge.
464 if (reference_processor()->processing_is_mt()) {
465 PSRefProcTaskExecutor task_executor;
466 reference_processor()->enqueue_discovered_references(&task_executor);
467 } else {
468 reference_processor()->enqueue_discovered_references(NULL);
469 }
470 }
471
472 {
473 GCTraceTime tm("StringTable", false, false, &_gc_timer, _gc_tracer.gc_id());
474 // Unlink any dead interned Strings and process the remaining live ones.
475 PSScavengeRootsClosure root_closure(promotion_manager);
476 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
477 }
478
479 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
480 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
481 if (promotion_failure_occurred) {
482 clean_up_failed_promotion();
483 if (PrintGC) {
484 gclog_or_tty->print("--");
485 }
486 }
487
488 // Let the size policy know we're done. Note that we count promotion
489 // failure cleanup time as part of the collection (otherwise, we're
490 // implicitly saying it's mutator time).
491 size_policy->minor_collection_end(gc_cause);
492
493 if (!promotion_failure_occurred) {
494 // Swap the survivor spaces.
495 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
496 young_gen->from_space()->clear(SpaceDecorator::Mangle);
497 young_gen->swap_spaces();
498
499 size_t survived = young_gen->from_space()->used_in_bytes();
500 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
501 size_policy->update_averages(_survivor_overflow, survived, promoted);
502
503 // A successful scavenge should restart the GC time limit count which is
504 // for full GC's.
505 size_policy->reset_gc_overhead_limit_count();
506 if (UseAdaptiveSizePolicy) {
507 // Calculate the new survivor size and tenuring threshold
508
509 if (PrintAdaptiveSizePolicy) {
510 gclog_or_tty->print("AdaptiveSizeStart: ");
511 gclog_or_tty->stamp();
512 gclog_or_tty->print_cr(" collection: %d ",
513 heap->total_collections());
514
515 if (Verbose) {
516 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
517 " young_gen_capacity: " SIZE_FORMAT,
518 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
519 }
520 }
521
522
523 if (UsePerfData) {
524 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
525 counters->update_old_eden_size(
526 size_policy->calculated_eden_size_in_bytes());
527 counters->update_old_promo_size(
528 size_policy->calculated_promo_size_in_bytes());
529 counters->update_old_capacity(old_gen->capacity_in_bytes());
530 counters->update_young_capacity(young_gen->capacity_in_bytes());
531 counters->update_survived(survived);
532 counters->update_promoted(promoted);
533 counters->update_survivor_overflowed(_survivor_overflow);
534 }
535
536 size_t max_young_size = young_gen->max_size();
537
538 // Deciding a free ratio in the young generation is tricky, so if
539 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
540 // that the old generation size may have been limited because of them) we
541 // should then limit our young generation size using NewRatio to have it
542 // follow the old generation size.
543 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
544 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
545 }
546
547 size_t survivor_limit =
548 size_policy->max_survivor_size(max_young_size);
549 _tenuring_threshold =
550 size_policy->compute_survivor_space_size_and_threshold(
551 _survivor_overflow,
552 _tenuring_threshold,
553 survivor_limit);
554
555 if (PrintTenuringDistribution) {
556 gclog_or_tty->cr();
557 gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold "
558 UINTX_FORMAT " (max threshold " UINTX_FORMAT ")",
559 size_policy->calculated_survivor_size_in_bytes(),
560 _tenuring_threshold, MaxTenuringThreshold);
561 }
562
563 if (UsePerfData) {
564 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
565 counters->update_tenuring_threshold(_tenuring_threshold);
566 counters->update_survivor_size_counters();
567 }
568
569 // Do call at minor collections?
570 // Don't check if the size_policy is ready at this
571 // level. Let the size_policy check that internally.
572 if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
573 ((gc_cause != GCCause::_java_lang_system_gc) ||
574 UseAdaptiveSizePolicyWithSystemGC)) {
575
576 // Calculate optimal free space amounts
577 assert(young_gen->max_size() >
578 young_gen->from_space()->capacity_in_bytes() +
579 young_gen->to_space()->capacity_in_bytes(),
580 "Sizes of space in young gen are out-of-bounds");
581
582 size_t young_live = young_gen->used_in_bytes();
583 size_t eden_live = young_gen->eden_space()->used_in_bytes();
584 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
585 size_t max_old_gen_size = old_gen->max_gen_size();
586 size_t max_eden_size = max_young_size -
587 young_gen->from_space()->capacity_in_bytes() -
588 young_gen->to_space()->capacity_in_bytes();
589
590 // Used for diagnostics
591 size_policy->clear_generation_free_space_flags();
592
593 size_policy->compute_eden_space_size(young_live,
594 eden_live,
595 cur_eden,
596 max_eden_size,
597 false /* not full gc*/);
598
599 size_policy->check_gc_overhead_limit(young_live,
600 eden_live,
601 max_old_gen_size,
602 max_eden_size,
603 false /* not full gc*/,
604 gc_cause,
605 heap->collector_policy());
606
607 size_policy->decay_supplemental_growth(false /* not full gc*/);
608 }
609 // Resize the young generation at every collection
610 // even if new sizes have not been calculated. This is
611 // to allow resizes that may have been inhibited by the
612 // relative location of the "to" and "from" spaces.
613
614 // Resizing the old gen at minor collects can cause increases
615 // that don't feed back to the generation sizing policy until
616 // a major collection. Don't resize the old gen here.
617
618 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
619 size_policy->calculated_survivor_size_in_bytes());
620
621 if (PrintAdaptiveSizePolicy) {
622 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
623 heap->total_collections());
624 }
625 }
626
627 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
628 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
629 // Also update() will case adaptive NUMA chunk resizing.
630 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
631 young_gen->eden_space()->update();
632
633 heap->gc_policy_counters()->update_counters();
634
635 heap->resize_all_tlabs();
636
637 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
638 }
639
640 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
641
642 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
643
644 {
645 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer, _gc_tracer.gc_id());
646
647 CodeCache::prune_scavenge_root_nmethods();
648 }
649
650 // Re-verify object start arrays
651 if (VerifyObjectStartArray &&
652 VerifyAfterGC) {
653 old_gen->verify_object_start_array();
654 }
655
656 // Verify all old -> young cards are now precise
657 if (VerifyRememberedSets) {
658 // Precise verification will give false positives. Until this is fixed,
659 // use imprecise verification.
660 // CardTableExtension::verify_all_young_refs_precise();
661 CardTableExtension::verify_all_young_refs_imprecise();
662 }
663
664 if (TraceYoungGenTime) accumulated_time()->stop();
665
666 if (PrintGC) {
667 if (PrintGCDetails) {
668 // Don't print a GC timestamp here. This is after the GC so
669 // would be confusing.
670 young_gen->print_used_change(young_gen_used_before);
671 }
672 heap->print_heap_change(prev_used);
673 }
674
675 // Track memory usage and detect low memory
676 MemoryService::track_memory_usage();
677 heap->update_counters();
678
679 gc_task_manager()->release_idle_workers();
680 }
681
682 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
683 HandleMark hm; // Discard invalid handles created during verification
684 Universe::verify(" VerifyAfterGC:");
685 }
686
687 heap->print_heap_after_gc();
688 heap->trace_heap_after_gc(&_gc_tracer);
689 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
690
691 if (ZapUnusedHeapArea) {
692 young_gen->eden_space()->check_mangled_unused_area_complete();
693 young_gen->from_space()->check_mangled_unused_area_complete();
694 young_gen->to_space()->check_mangled_unused_area_complete();
695 }
696
697 scavenge_exit.update();
698
699 if (PrintGCTaskTimeStamps) {
700 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT,
701 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
702 scavenge_exit.ticks());
703 gc_task_manager()->print_task_time_stamps();
704 }
705
706 #ifdef TRACESPINNING
707 ParallelTaskTerminator::print_termination_counts();
708 #endif
709
710
711 _gc_timer.register_gc_end();
712
713 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
714
715 return !promotion_failure_occurred;
716 }
717
718 // This method iterates over all objects in the young generation,
719 // unforwarding markOops. It then restores any preserved mark oops,
720 // and clears the _preserved_mark_stack.
721 void PSScavenge::clean_up_failed_promotion() {
722 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
723 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
724
725 PSYoungGen* young_gen = heap->young_gen();
726
727 {
728 ResourceMark rm;
729
730 // Unforward all pointers in the young gen.
731 PSPromotionFailedClosure unforward_closure;
732 young_gen->object_iterate(&unforward_closure);
733
734 if (PrintGC && Verbose) {
735 gclog_or_tty->print_cr("Restoring " SIZE_FORMAT " marks", _preserved_oop_stack.size());
736 }
737
738 // Restore any saved marks.
739 while (!_preserved_oop_stack.is_empty()) {
740 oop obj = _preserved_oop_stack.pop();
741 markOop mark = _preserved_mark_stack.pop();
742 obj->set_mark(mark);
743 }
744
745 // Clear the preserved mark and oop stack caches.
746 _preserved_mark_stack.clear(true);
747 _preserved_oop_stack.clear(true);
748 }
749
750 // Reset the PromotionFailureALot counters.
751 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
752 }
753
754 // This method is called whenever an attempt to promote an object
755 // fails. Some markOops will need preservation, some will not. Note
756 // that the entire eden is traversed after a failed promotion, with
757 // all forwarded headers replaced by the default markOop. This means
758 // it is not necessary to preserve most markOops.
759 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
760 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
761 // Should use per-worker private stacks here rather than
762 // locking a common pair of stacks.
763 ThreadCritical tc;
764 _preserved_oop_stack.push(obj);
765 _preserved_mark_stack.push(obj_mark);
766 }
767 }
768
769 bool PSScavenge::should_attempt_scavenge() {
770 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
771 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
772 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
773
774 if (UsePerfData) {
775 counters->update_scavenge_skipped(not_skipped);
776 }
777
778 PSYoungGen* young_gen = heap->young_gen();
779 PSOldGen* old_gen = heap->old_gen();
780
781 if (!ScavengeWithObjectsInToSpace) {
782 // Do not attempt to promote unless to_space is empty
783 if (!young_gen->to_space()->is_empty()) {
784 _consecutive_skipped_scavenges++;
785 if (UsePerfData) {
786 counters->update_scavenge_skipped(to_space_not_empty);
787 }
788 return false;
789 }
790 }
791
792 // Test to see if the scavenge will likely fail.
793 PSAdaptiveSizePolicy* policy = heap->size_policy();
794
795 // A similar test is done in the policy's should_full_GC(). If this is
796 // changed, decide if that test should also be changed.
797 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
798 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
799 bool result = promotion_estimate < old_gen->free_in_bytes();
800
801 if (PrintGCDetails && Verbose) {
802 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: ");
803 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
804 " padded_average_promoted " SIZE_FORMAT
805 " free in old gen " SIZE_FORMAT,
806 (size_t) policy->average_promoted_in_bytes(),
807 (size_t) policy->padded_average_promoted_in_bytes(),
808 old_gen->free_in_bytes());
809 if (young_gen->used_in_bytes() <
810 (size_t) policy->padded_average_promoted_in_bytes()) {
811 gclog_or_tty->print_cr(" padded_promoted_average is greater"
812 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
813 }
814 }
815
816 if (result) {
817 _consecutive_skipped_scavenges = 0;
818 } else {
819 _consecutive_skipped_scavenges++;
820 if (UsePerfData) {
821 counters->update_scavenge_skipped(promoted_too_large);
822 }
823 }
824 return result;
825 }
826
827 // Used to add tasks
828 GCTaskManager* const PSScavenge::gc_task_manager() {
829 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
830 "shouldn't return NULL");
831 return ParallelScavengeHeap::gc_task_manager();
832 }
833
834 void PSScavenge::initialize() {
835 // Arguments must have been parsed
836
837 if (AlwaysTenure || NeverTenure) {
838 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1,
839 err_msg("MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold));
840 _tenuring_threshold = MaxTenuringThreshold;
841 } else {
842 // We want to smooth out our startup times for the AdaptiveSizePolicy
843 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
844 MaxTenuringThreshold;
845 }
846
847 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
848 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
849
850 PSYoungGen* young_gen = heap->young_gen();
851 PSOldGen* old_gen = heap->old_gen();
852
853 // Set boundary between young_gen and old_gen
854 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
855 "old above young");
856 set_young_generation_boundary(young_gen->eden_space()->bottom());
857
858 // Initialize ref handling object for scavenging.
859 MemRegion mr = young_gen->reserved();
860
861 _ref_processor =
862 new ReferenceProcessor(mr, // span
863 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
864 (int) ParallelGCThreads, // mt processing degree
865 true, // mt discovery
866 (int) ParallelGCThreads, // mt discovery degree
867 true, // atomic_discovery
868 NULL); // header provides liveness info
869
870 // Cache the cardtable
871 BarrierSet* bs = Universe::heap()->barrier_set();
872 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
873 _card_table = (CardTableExtension*)bs;
874
875 _counters = new CollectorCounters("PSScavenge", 0);
876 }