1 /*
2 * Copyright (c) 2002, 2013, 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/symbolTable.hpp"
27 #include "code/codeCache.hpp"
28 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
30 #include "gc_implementation/parallelScavenge/generationSizer.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/gcCause.hpp"
44 #include "memory/collectorPolicy.hpp"
45 #include "memory/gcLocker.inline.hpp"
46 #include "memory/referencePolicy.hpp"
47 #include "memory/referenceProcessor.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "oops/oop.psgc.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
61 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
62 int PSScavenge::_consecutive_skipped_scavenges = 0;
63 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
64 CardTableExtension* PSScavenge::_card_table = NULL;
65 bool PSScavenge::_survivor_overflow = false;
66 uint PSScavenge::_tenuring_threshold = 0;
67 HeapWord* PSScavenge::_young_generation_boundary = NULL;
68 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0;
69 elapsedTimer PSScavenge::_accumulated_time;
70 STWGCTimer PSScavenge::_gc_timer;
71 ParallelScavengeTracer PSScavenge::_gc_tracer;
72 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack;
73 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack;
74 CollectorCounters* PSScavenge::_counters = NULL;
75
76 // Define before use
77 class PSIsAliveClosure: public BoolObjectClosure {
78 public:
79 bool do_object_b(oop p) {
80 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
81 }
82 };
83
84 PSIsAliveClosure PSScavenge::_is_alive_closure;
85
86 class PSKeepAliveClosure: public OopClosure {
87 protected:
88 MutableSpace* _to_space;
89 PSPromotionManager* _promotion_manager;
90
91 public:
92 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
93 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
94 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
95 _to_space = heap->young_gen()->to_space();
96
97 assert(_promotion_manager != NULL, "Sanity");
98 }
99
100 template <class T> void do_oop_work(T* p) {
101 assert (!oopDesc::is_null(*p), "expected non-null ref");
102 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
103 "expected an oop while scanning weak refs");
104
105 // Weak refs may be visited more than once.
106 if (PSScavenge::should_scavenge(p, _to_space)) {
107 PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p);
108 }
109 }
110 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
111 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
112 };
113
114 class PSEvacuateFollowersClosure: public VoidClosure {
115 private:
116 PSPromotionManager* _promotion_manager;
117 public:
118 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
119
120 virtual void do_void() {
121 assert(_promotion_manager != NULL, "Sanity");
122 _promotion_manager->drain_stacks(true);
123 guarantee(_promotion_manager->stacks_empty(),
124 "stacks should be empty at this point");
125 }
126 };
127
128 class PSPromotionFailedClosure : public ObjectClosure {
129 virtual void do_object(oop obj) {
130 if (obj->is_forwarded()) {
131 obj->init_mark();
132 }
133 }
134 };
135
136 class PSRefProcTaskProxy: public GCTask {
137 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
138 ProcessTask & _rp_task;
139 uint _work_id;
140 public:
141 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
142 : _rp_task(rp_task),
143 _work_id(work_id)
144 { }
145
146 private:
147 virtual char* name() { return (char *)"Process referents by policy in parallel"; }
148 virtual void do_it(GCTaskManager* manager, uint which);
149 };
150
151 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
152 {
153 PSPromotionManager* promotion_manager =
154 PSPromotionManager::gc_thread_promotion_manager(which);
155 assert(promotion_manager != NULL, "sanity check");
156 PSKeepAliveClosure keep_alive(promotion_manager);
157 PSEvacuateFollowersClosure evac_followers(promotion_manager);
158 PSIsAliveClosure is_alive;
159 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
160 }
161
162 class PSRefEnqueueTaskProxy: public GCTask {
163 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
164 EnqueueTask& _enq_task;
165 uint _work_id;
166
167 public:
168 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
169 : _enq_task(enq_task),
170 _work_id(work_id)
171 { }
172
173 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
174 virtual void do_it(GCTaskManager* manager, uint which)
175 {
176 _enq_task.work(_work_id);
177 }
178 };
179
180 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
181 virtual void execute(ProcessTask& task);
182 virtual void execute(EnqueueTask& task);
183 };
184
185 void PSRefProcTaskExecutor::execute(ProcessTask& task)
186 {
187 GCTaskQueue* q = GCTaskQueue::create();
188 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
189 for(uint i=0; i < manager->active_workers(); i++) {
190 q->enqueue(new PSRefProcTaskProxy(task, i));
191 }
192 ParallelTaskTerminator terminator(manager->active_workers(),
193 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
194 if (task.marks_oops_alive() && manager->active_workers() > 1) {
195 for (uint j = 0; j < manager->active_workers(); j++) {
196 q->enqueue(new StealTask(&terminator));
197 }
198 }
199 manager->execute_and_wait(q);
200 }
201
202
203 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
204 {
205 GCTaskQueue* q = GCTaskQueue::create();
206 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
207 for(uint i=0; i < manager->active_workers(); i++) {
208 q->enqueue(new PSRefEnqueueTaskProxy(task, i));
209 }
210 manager->execute_and_wait(q);
211 }
212
213 // This method contains all heap specific policy for invoking scavenge.
214 // PSScavenge::invoke_no_policy() will do nothing but attempt to
215 // scavenge. It will not clean up after failed promotions, bail out if
216 // we've exceeded policy time limits, or any other special behavior.
217 // All such policy should be placed here.
218 //
219 // Note that this method should only be called from the vm_thread while
220 // at a safepoint!
221 bool PSScavenge::invoke() {
222 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
223 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
224 assert(!Universe::heap()->is_gc_active(), "not reentrant");
225
226 ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap();
227 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
228
229 PSAdaptiveSizePolicy* policy = heap->size_policy();
230 IsGCActiveMark mark;
231
232 const bool scavenge_done = PSScavenge::invoke_no_policy();
233 const bool need_full_gc = !scavenge_done ||
234 policy->should_full_GC(heap->old_gen()->free_in_bytes());
235 bool full_gc_done = false;
236
237 if (UsePerfData) {
238 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
239 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
240 counters->update_full_follows_scavenge(ffs_val);
241 }
242
243 if (need_full_gc) {
244 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
245 CollectorPolicy* cp = heap->collector_policy();
246 const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
247
248 if (UseParallelOldGC) {
249 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
250 } else {
251 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
252 }
253 }
254
255 return full_gc_done;
256 }
257
258 // This method contains no policy. You should probably
259 // be calling invoke() instead.
260 bool PSScavenge::invoke_no_policy() {
261 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
262 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
263
264 assert(_preserved_mark_stack.is_empty(), "should be empty");
265 assert(_preserved_oop_stack.is_empty(), "should be empty");
266
267 _gc_timer.register_gc_start(os::elapsed_counter());
268
269 TimeStamp scavenge_entry;
270 TimeStamp scavenge_midpoint;
271 TimeStamp scavenge_exit;
272
273 scavenge_entry.update();
274
275 if (GC_locker::check_active_before_gc()) {
276 return false;
277 }
278
279 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
280 GCCause::Cause gc_cause = heap->gc_cause();
281 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
282
283 // Check for potential problems.
284 if (!should_attempt_scavenge()) {
285 return false;
286 }
287
288 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
289
290 bool promotion_failure_occurred = false;
291
292 PSYoungGen* young_gen = heap->young_gen();
293 PSOldGen* old_gen = heap->old_gen();
294 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
295
296 heap->increment_total_collections();
297
298 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
299
300 if ((gc_cause != GCCause::_java_lang_system_gc) ||
301 UseAdaptiveSizePolicyWithSystemGC) {
302 // Gather the feedback data for eden occupancy.
303 young_gen->eden_space()->accumulate_statistics();
304 }
305
306 if (ZapUnusedHeapArea) {
307 // Save information needed to minimize mangling
308 heap->record_gen_tops_before_GC();
309 }
310
311 heap->print_heap_before_gc();
312 heap->trace_heap_before_gc(&_gc_tracer);
313
314 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
315 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
316
317 size_t prev_used = heap->used();
318
319 // Fill in TLABs
320 heap->accumulate_statistics_all_tlabs();
321 heap->ensure_parsability(true); // retire TLABs
322
323 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
324 HandleMark hm; // Discard invalid handles created during verification
325 Universe::verify(" VerifyBeforeGC:");
326 }
327
328 {
329 ResourceMark rm;
330 HandleMark hm;
331
332 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
333 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
334 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
335 TraceCollectorStats tcs(counters());
336 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
337
338 if (TraceGen0Time) accumulated_time()->start();
339
340 // Let the size policy know we're starting
341 size_policy->minor_collection_begin();
342
343 // Verify the object start arrays.
344 if (VerifyObjectStartArray &&
345 VerifyBeforeGC) {
346 old_gen->verify_object_start_array();
347 }
348
349 // Verify no unmarked old->young roots
350 if (VerifyRememberedSets) {
351 CardTableExtension::verify_all_young_refs_imprecise();
352 }
353
354 if (!ScavengeWithObjectsInToSpace) {
355 assert(young_gen->to_space()->is_empty(),
356 "Attempt to scavenge with live objects in to_space");
357 young_gen->to_space()->clear(SpaceDecorator::Mangle);
358 } else if (ZapUnusedHeapArea) {
359 young_gen->to_space()->mangle_unused_area();
360 }
361 save_to_space_top_before_gc();
362
363 COMPILER2_PRESENT(DerivedPointerTable::clear());
364
365 reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
366 reference_processor()->setup_policy(false);
367
368 // We track how much was promoted to the next generation for
369 // the AdaptiveSizePolicy.
370 size_t old_gen_used_before = old_gen->used_in_bytes();
371
372 // For PrintGCDetails
373 size_t young_gen_used_before = young_gen->used_in_bytes();
374
375 // Reset our survivor overflow.
376 set_survivor_overflow(false);
377
378 // We need to save the old top values before
379 // creating the promotion_manager. We pass the top
380 // values to the card_table, to prevent it from
381 // straying into the promotion labs.
382 HeapWord* old_top = old_gen->object_space()->top();
383
384 // Release all previously held resources
385 gc_task_manager()->release_all_resources();
386
387 // Set the number of GC threads to be used in this collection
388 gc_task_manager()->set_active_gang();
389 gc_task_manager()->task_idle_workers();
390 // Get the active number of workers here and use that value
391 // throughout the methods.
392 uint active_workers = gc_task_manager()->active_workers();
393 heap->set_par_threads(active_workers);
394
395 PSPromotionManager::pre_scavenge();
396
397 // We'll use the promotion manager again later.
398 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
399 {
400 GCTraceTime tm("Scavenge", false, false, &_gc_timer);
401 ParallelScavengeHeap::ParStrongRootsScope psrs;
402
403 GCTaskQueue* q = GCTaskQueue::create();
404
405 if (!old_gen->object_space()->is_empty()) {
406 // There are only old-to-young pointers if there are objects
407 // in the old gen.
408 uint stripe_total = active_workers;
409 for(uint i=0; i < stripe_total; i++) {
410 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
411 }
412 }
413
414 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
415 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
416 // We scan the thread roots in parallel
417 Threads::create_thread_roots_tasks(q);
418 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
419 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
420 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
421 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
422 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data));
423 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
424 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
425
426 ParallelTaskTerminator terminator(
427 active_workers,
428 (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
429 if (active_workers > 1) {
430 for (uint j = 0; j < active_workers; j++) {
431 q->enqueue(new StealTask(&terminator));
432 }
433 }
434
435 gc_task_manager()->execute_and_wait(q);
436 }
437
438 scavenge_midpoint.update();
439
440 // Process reference objects discovered during scavenge
441 {
442 GCTraceTime tm("References", false, false, &_gc_timer);
443
444 reference_processor()->setup_policy(false); // not always_clear
445 reference_processor()->set_active_mt_degree(active_workers);
446 PSKeepAliveClosure keep_alive(promotion_manager);
447 PSEvacuateFollowersClosure evac_followers(promotion_manager);
448 ReferenceProcessorStats stats;
449 if (reference_processor()->processing_is_mt()) {
450 PSRefProcTaskExecutor task_executor;
451 stats = reference_processor()->process_discovered_references(
452 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
453 &_gc_timer);
454 } else {
455 stats = reference_processor()->process_discovered_references(
456 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer);
457 }
458
459 _gc_tracer.report_gc_reference_stats(stats);
460
461 // Enqueue reference objects discovered during scavenge.
462 if (reference_processor()->processing_is_mt()) {
463 PSRefProcTaskExecutor task_executor;
464 reference_processor()->enqueue_discovered_references(&task_executor);
465 } else {
466 reference_processor()->enqueue_discovered_references(NULL);
467 }
468 }
469
470 GCTraceTime tm("StringTable", false, false, &_gc_timer);
471 // Unlink any dead interned Strings and process the remaining live ones.
472 PSScavengeRootsClosure root_closure(promotion_manager);
473 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
474
475 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
476 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
477 if (promotion_failure_occurred) {
478 clean_up_failed_promotion();
479 if (PrintGC) {
480 gclog_or_tty->print("--");
481 }
482 }
483
484 // Let the size policy know we're done. Note that we count promotion
485 // failure cleanup time as part of the collection (otherwise, we're
486 // implicitly saying it's mutator time).
487 size_policy->minor_collection_end(gc_cause);
488
489 if (!promotion_failure_occurred) {
490 // Swap the survivor spaces.
491 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
492 young_gen->from_space()->clear(SpaceDecorator::Mangle);
493 young_gen->swap_spaces();
494
495 size_t survived = young_gen->from_space()->used_in_bytes();
496 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
497 size_policy->update_averages(_survivor_overflow, survived, promoted);
498
499 // A successful scavenge should restart the GC time limit count which is
500 // for full GC's.
501 size_policy->reset_gc_overhead_limit_count();
502 if (UseAdaptiveSizePolicy) {
503 // Calculate the new survivor size and tenuring threshold
504
505 if (PrintAdaptiveSizePolicy) {
506 gclog_or_tty->print("AdaptiveSizeStart: ");
507 gclog_or_tty->stamp();
508 gclog_or_tty->print_cr(" collection: %d ",
509 heap->total_collections());
510
511 if (Verbose) {
512 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
513 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
514 }
515 }
516
517
518 if (UsePerfData) {
519 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
520 counters->update_old_eden_size(
521 size_policy->calculated_eden_size_in_bytes());
522 counters->update_old_promo_size(
523 size_policy->calculated_promo_size_in_bytes());
524 counters->update_old_capacity(old_gen->capacity_in_bytes());
525 counters->update_young_capacity(young_gen->capacity_in_bytes());
526 counters->update_survived(survived);
527 counters->update_promoted(promoted);
528 counters->update_survivor_overflowed(_survivor_overflow);
529 }
530
531 size_t survivor_limit =
532 size_policy->max_survivor_size(young_gen->max_size());
533 _tenuring_threshold =
534 size_policy->compute_survivor_space_size_and_threshold(
535 _survivor_overflow,
536 _tenuring_threshold,
537 survivor_limit);
538
539 if (PrintTenuringDistribution) {
540 gclog_or_tty->cr();
541 gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold %u)",
542 size_policy->calculated_survivor_size_in_bytes(),
543 _tenuring_threshold, MaxTenuringThreshold);
544 }
545
546 if (UsePerfData) {
547 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
548 counters->update_tenuring_threshold(_tenuring_threshold);
549 counters->update_survivor_size_counters();
550 }
551
552 // Do call at minor collections?
553 // Don't check if the size_policy is ready at this
554 // level. Let the size_policy check that internally.
555 if (UseAdaptiveSizePolicy &&
556 UseAdaptiveGenerationSizePolicyAtMinorCollection &&
557 ((gc_cause != GCCause::_java_lang_system_gc) ||
558 UseAdaptiveSizePolicyWithSystemGC)) {
559
560 // Calculate optimial 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 = young_gen->max_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 minor collects can cause increases
599 // that don't feed back to the generation sizing policy until
600 // a major 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 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
625
626 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
627
628 {
629 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer);
630
631 CodeCache::prune_scavenge_root_nmethods();
632 }
633
634 // Re-verify object start arrays
635 if (VerifyObjectStartArray &&
636 VerifyAfterGC) {
637 old_gen->verify_object_start_array();
638 }
639
640 // Verify all old -> young cards are now precise
641 if (VerifyRememberedSets) {
642 // Precise verification will give false positives. Until this is fixed,
643 // use imprecise verification.
644 // CardTableExtension::verify_all_young_refs_precise();
645 CardTableExtension::verify_all_young_refs_imprecise();
646 }
647
648 if (TraceGen0Time) accumulated_time()->stop();
649
650 if (PrintGC) {
651 if (PrintGCDetails) {
652 // Don't print a GC timestamp here. This is after the GC so
653 // would be confusing.
654 young_gen->print_used_change(young_gen_used_before);
655 }
656 heap->print_heap_change(prev_used);
657 }
658
659 // Track memory usage and detect low memory
660 MemoryService::track_memory_usage();
661 heap->update_counters();
662
663 gc_task_manager()->release_idle_workers();
664 }
665
666 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
667 HandleMark hm; // Discard invalid handles created during verification
668 Universe::verify(" VerifyAfterGC:");
669 }
670
671 heap->print_heap_after_gc();
672 heap->trace_heap_after_gc(&_gc_tracer);
673 _gc_tracer.report_tenuring_threshold(tenuring_threshold());
674
675 if (ZapUnusedHeapArea) {
676 young_gen->eden_space()->check_mangled_unused_area_complete();
677 young_gen->from_space()->check_mangled_unused_area_complete();
678 young_gen->to_space()->check_mangled_unused_area_complete();
679 }
680
681 scavenge_exit.update();
682
683 if (PrintGCTaskTimeStamps) {
684 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT,
685 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
686 scavenge_exit.ticks());
687 gc_task_manager()->print_task_time_stamps();
688 }
689
690 #ifdef TRACESPINNING
691 ParallelTaskTerminator::print_termination_counts();
692 #endif
693
694
695 _gc_timer.register_gc_end(os::elapsed_counter());
696
697 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
698
699 return !promotion_failure_occurred;
700 }
701
702 // This method iterates over all objects in the young generation,
703 // unforwarding markOops. It then restores any preserved mark oops,
704 // and clears the _preserved_mark_stack.
705 void PSScavenge::clean_up_failed_promotion() {
706 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
707 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
708
709 PSYoungGen* young_gen = heap->young_gen();
710
711 {
712 ResourceMark rm;
713
714 // Unforward all pointers in the young gen.
715 PSPromotionFailedClosure unforward_closure;
716 young_gen->object_iterate(&unforward_closure);
717
718 if (PrintGC && Verbose) {
719 gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size());
720 }
721
722 // Restore any saved marks.
723 while (!_preserved_oop_stack.is_empty()) {
724 oop obj = _preserved_oop_stack.pop();
725 markOop mark = _preserved_mark_stack.pop();
726 obj->set_mark(mark);
727 }
728
729 // Clear the preserved mark and oop stack caches.
730 _preserved_mark_stack.clear(true);
731 _preserved_oop_stack.clear(true);
732 }
733
734 // Reset the PromotionFailureALot counters.
735 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
736 }
737
738 // This method is called whenever an attempt to promote an object
739 // fails. Some markOops will need preservation, some will not. Note
740 // that the entire eden is traversed after a failed promotion, with
741 // all forwarded headers replaced by the default markOop. This means
742 // it is not necessary to preserve most markOops.
743 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
744 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
745 // Should use per-worker private stacks here rather than
746 // locking a common pair of stacks.
747 ThreadCritical tc;
748 _preserved_oop_stack.push(obj);
749 _preserved_mark_stack.push(obj_mark);
750 }
751 }
752
753 bool PSScavenge::should_attempt_scavenge() {
754 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
755 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
756 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
757
758 if (UsePerfData) {
759 counters->update_scavenge_skipped(not_skipped);
760 }
761
762 PSYoungGen* young_gen = heap->young_gen();
763 PSOldGen* old_gen = heap->old_gen();
764
765 if (!ScavengeWithObjectsInToSpace) {
766 // Do not attempt to promote unless to_space is empty
767 if (!young_gen->to_space()->is_empty()) {
768 _consecutive_skipped_scavenges++;
769 if (UsePerfData) {
770 counters->update_scavenge_skipped(to_space_not_empty);
771 }
772 return false;
773 }
774 }
775
776 // Test to see if the scavenge will likely fail.
777 PSAdaptiveSizePolicy* policy = heap->size_policy();
778
779 // A similar test is done in the policy's should_full_GC(). If this is
780 // changed, decide if that test should also be changed.
781 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
782 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
783 bool result = promotion_estimate < old_gen->free_in_bytes();
784
785 if (PrintGCDetails && Verbose) {
786 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: ");
787 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
788 " padded_average_promoted " SIZE_FORMAT
789 " free in old gen " SIZE_FORMAT,
790 (size_t) policy->average_promoted_in_bytes(),
791 (size_t) policy->padded_average_promoted_in_bytes(),
792 old_gen->free_in_bytes());
793 if (young_gen->used_in_bytes() <
794 (size_t) policy->padded_average_promoted_in_bytes()) {
795 gclog_or_tty->print_cr(" padded_promoted_average is greater"
796 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
797 }
798 }
799
800 if (result) {
801 _consecutive_skipped_scavenges = 0;
802 } else {
803 _consecutive_skipped_scavenges++;
804 if (UsePerfData) {
805 counters->update_scavenge_skipped(promoted_too_large);
806 }
807 }
808 return result;
809 }
810
811 // Used to add tasks
812 GCTaskManager* const PSScavenge::gc_task_manager() {
813 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
814 "shouldn't return NULL");
815 return ParallelScavengeHeap::gc_task_manager();
816 }
817
818 void PSScavenge::initialize() {
819 // Arguments must have been parsed
820
821 if (AlwaysTenure || NeverTenure) {
822 _tenuring_threshold = MaxTenuringThreshold;
823 } else {
824 // We want to smooth out our startup times for the AdaptiveSizePolicy
825 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
826 MaxTenuringThreshold;
827 }
828
829 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
830 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
831
832 PSYoungGen* young_gen = heap->young_gen();
833 PSOldGen* old_gen = heap->old_gen();
834
835 // Set boundary between young_gen and old_gen
836 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
837 "old above young");
838 set_young_generation_boundary(young_gen->eden_space()->bottom());
839
840 // Initialize ref handling object for scavenging.
841 MemRegion mr = young_gen->reserved();
842
843 _ref_processor =
844 new ReferenceProcessor(mr, // span
845 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
846 (int) ParallelGCThreads, // mt processing degree
847 true, // mt discovery
848 (int) ParallelGCThreads, // mt discovery degree
849 true, // atomic_discovery
850 NULL, // header provides liveness info
851 false); // next field updates do not need write barrier
852
853 // Cache the cardtable
854 BarrierSet* bs = Universe::heap()->barrier_set();
855 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
856 _card_table = (CardTableExtension*)bs;
857
858 _counters = new CollectorCounters("PSScavenge", 0);
859 }