1 /*
2 * Copyright (c) 2002, 2010, 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
26 # include "incls/_precompiled.incl"
27 # include "incls/_psScavenge.cpp.incl"
28
29 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
30 int PSScavenge::_consecutive_skipped_scavenges = 0;
31 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
32 CardTableExtension* PSScavenge::_card_table = NULL;
33 bool PSScavenge::_survivor_overflow = false;
34 int PSScavenge::_tenuring_threshold = 0;
35 HeapWord* PSScavenge::_young_generation_boundary = NULL;
36 elapsedTimer PSScavenge::_accumulated_time;
37 GrowableArray<markOop>* PSScavenge::_preserved_mark_stack = NULL;
38 GrowableArray<oop>* PSScavenge::_preserved_oop_stack = NULL;
39 CollectorCounters* PSScavenge::_counters = NULL;
40
41 // Define before use
42 class PSIsAliveClosure: public BoolObjectClosure {
43 public:
44 void do_object(oop p) {
45 assert(false, "Do not call.");
46 }
47 bool do_object_b(oop p) {
48 return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded();
49 }
50 };
51
52 PSIsAliveClosure PSScavenge::_is_alive_closure;
53
54 class PSKeepAliveClosure: public OopClosure {
55 protected:
56 MutableSpace* _to_space;
57 PSPromotionManager* _promotion_manager;
58
59 public:
60 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
61 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
62 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
63 _to_space = heap->young_gen()->to_space();
64
65 assert(_promotion_manager != NULL, "Sanity");
66 }
67
68 template <class T> void do_oop_work(T* p) {
69 assert (!oopDesc::is_null(*p), "expected non-null ref");
70 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
71 "expected an oop while scanning weak refs");
72
73 // Weak refs may be visited more than once.
74 if (PSScavenge::should_scavenge(p, _to_space)) {
75 PSScavenge::copy_and_push_safe_barrier(_promotion_manager, p);
76 }
77 }
78 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); }
79 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
80 };
81
82 class PSEvacuateFollowersClosure: public VoidClosure {
83 private:
84 PSPromotionManager* _promotion_manager;
85 public:
86 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
87
88 virtual void do_void() {
89 assert(_promotion_manager != NULL, "Sanity");
90 _promotion_manager->drain_stacks(true);
91 guarantee(_promotion_manager->stacks_empty(),
92 "stacks should be empty at this point");
93 }
94 };
95
96 class PSPromotionFailedClosure : public ObjectClosure {
97 virtual void do_object(oop obj) {
98 if (obj->is_forwarded()) {
99 obj->init_mark();
100 }
101 }
102 };
103
104 class PSRefProcTaskProxy: public GCTask {
105 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
106 ProcessTask & _rp_task;
107 uint _work_id;
108 public:
109 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
110 : _rp_task(rp_task),
111 _work_id(work_id)
112 { }
113
114 private:
115 virtual char* name() { return (char *)"Process referents by policy in parallel"; }
116 virtual void do_it(GCTaskManager* manager, uint which);
117 };
118
119 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
120 {
121 PSPromotionManager* promotion_manager =
122 PSPromotionManager::gc_thread_promotion_manager(which);
123 assert(promotion_manager != NULL, "sanity check");
124 PSKeepAliveClosure keep_alive(promotion_manager);
125 PSEvacuateFollowersClosure evac_followers(promotion_manager);
126 PSIsAliveClosure is_alive;
127 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
128 }
129
130 class PSRefEnqueueTaskProxy: public GCTask {
131 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
132 EnqueueTask& _enq_task;
133 uint _work_id;
134
135 public:
136 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
137 : _enq_task(enq_task),
138 _work_id(work_id)
139 { }
140
141 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
142 virtual void do_it(GCTaskManager* manager, uint which)
143 {
144 _enq_task.work(_work_id);
145 }
146 };
147
148 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
149 virtual void execute(ProcessTask& task);
150 virtual void execute(EnqueueTask& task);
151 };
152
153 void PSRefProcTaskExecutor::execute(ProcessTask& task)
154 {
155 GCTaskQueue* q = GCTaskQueue::create();
156 for(uint i=0; i<ParallelGCThreads; i++) {
157 q->enqueue(new PSRefProcTaskProxy(task, i));
158 }
159 ParallelTaskTerminator terminator(
160 ParallelScavengeHeap::gc_task_manager()->workers(),
161 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
162 if (task.marks_oops_alive() && ParallelGCThreads > 1) {
163 for (uint j=0; j<ParallelGCThreads; j++) {
164 q->enqueue(new StealTask(&terminator));
165 }
166 }
167 ParallelScavengeHeap::gc_task_manager()->execute_and_wait(q);
168 }
169
170
171 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
172 {
173 GCTaskQueue* q = GCTaskQueue::create();
174 for(uint i=0; i<ParallelGCThreads; i++) {
175 q->enqueue(new PSRefEnqueueTaskProxy(task, i));
176 }
177 ParallelScavengeHeap::gc_task_manager()->execute_and_wait(q);
178 }
179
180 // This method contains all heap specific policy for invoking scavenge.
181 // PSScavenge::invoke_no_policy() will do nothing but attempt to
182 // scavenge. It will not clean up after failed promotions, bail out if
183 // we've exceeded policy time limits, or any other special behavior.
184 // All such policy should be placed here.
185 //
186 // Note that this method should only be called from the vm_thread while
187 // at a safepoint!
188 void PSScavenge::invoke() {
189 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
190 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
191 assert(!Universe::heap()->is_gc_active(), "not reentrant");
192
193 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
194 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
195
196 PSAdaptiveSizePolicy* policy = heap->size_policy();
197 IsGCActiveMark mark;
198
199 bool scavenge_was_done = PSScavenge::invoke_no_policy();
200
201 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
202 if (UsePerfData)
203 counters->update_full_follows_scavenge(0);
204 if (!scavenge_was_done ||
205 policy->should_full_GC(heap->old_gen()->free_in_bytes())) {
206 if (UsePerfData)
207 counters->update_full_follows_scavenge(full_follows_scavenge);
208 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
209 CollectorPolicy* cp = heap->collector_policy();
210 const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
211
212 if (UseParallelOldGC) {
213 PSParallelCompact::invoke_no_policy(clear_all_softrefs);
214 } else {
215 PSMarkSweep::invoke_no_policy(clear_all_softrefs);
216 }
217 }
218 }
219
220 // This method contains no policy. You should probably
221 // be calling invoke() instead.
222 bool PSScavenge::invoke_no_policy() {
223 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
224 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
225
226 TimeStamp scavenge_entry;
227 TimeStamp scavenge_midpoint;
228 TimeStamp scavenge_exit;
229
230 scavenge_entry.update();
231
232 if (GC_locker::check_active_before_gc()) {
233 return false;
234 }
235
236 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
237 GCCause::Cause gc_cause = heap->gc_cause();
238 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
239
240 // Check for potential problems.
241 if (!should_attempt_scavenge()) {
242 return false;
243 }
244
245 bool promotion_failure_occurred = false;
246
247 PSYoungGen* young_gen = heap->young_gen();
248 PSOldGen* old_gen = heap->old_gen();
249 PSPermGen* perm_gen = heap->perm_gen();
250 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
251 heap->increment_total_collections();
252
253 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
254
255 if ((gc_cause != GCCause::_java_lang_system_gc) ||
256 UseAdaptiveSizePolicyWithSystemGC) {
257 // Gather the feedback data for eden occupancy.
258 young_gen->eden_space()->accumulate_statistics();
259 }
260
261 if (ZapUnusedHeapArea) {
262 // Save information needed to minimize mangling
263 heap->record_gen_tops_before_GC();
264 }
265
266 if (PrintHeapAtGC) {
267 Universe::print_heap_before_gc();
268 }
269
270 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
271 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
272
273 size_t prev_used = heap->used();
274 assert(promotion_failed() == false, "Sanity");
275
276 // Fill in TLABs
277 heap->accumulate_statistics_all_tlabs();
278 heap->ensure_parsability(true); // retire TLABs
279
280 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
281 HandleMark hm; // Discard invalid handles created during verification
282 gclog_or_tty->print(" VerifyBeforeGC:");
283 Universe::verify(true);
284 }
285
286 {
287 ResourceMark rm;
288 HandleMark hm;
289
290 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
291 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
292 TraceTime t1("GC", PrintGC, !PrintGCDetails, gclog_or_tty);
293 TraceCollectorStats tcs(counters());
294 TraceMemoryManagerStats tms(false /* not full GC */);
295
296 if (TraceGen0Time) accumulated_time()->start();
297
298 // Let the size policy know we're starting
299 size_policy->minor_collection_begin();
300
301 // Verify the object start arrays.
302 if (VerifyObjectStartArray &&
303 VerifyBeforeGC) {
304 old_gen->verify_object_start_array();
305 perm_gen->verify_object_start_array();
306 }
307
308 // Verify no unmarked old->young roots
309 if (VerifyRememberedSets) {
310 CardTableExtension::verify_all_young_refs_imprecise();
311 }
312
313 if (!ScavengeWithObjectsInToSpace) {
314 assert(young_gen->to_space()->is_empty(),
315 "Attempt to scavenge with live objects in to_space");
316 young_gen->to_space()->clear(SpaceDecorator::Mangle);
317 } else if (ZapUnusedHeapArea) {
318 young_gen->to_space()->mangle_unused_area();
319 }
320 save_to_space_top_before_gc();
321
322 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
323 COMPILER2_PRESENT(DerivedPointerTable::clear());
324
325 reference_processor()->enable_discovery();
326 reference_processor()->setup_policy(false);
327
328 // We track how much was promoted to the next generation for
329 // the AdaptiveSizePolicy.
330 size_t old_gen_used_before = old_gen->used_in_bytes();
331
332 // For PrintGCDetails
333 size_t young_gen_used_before = young_gen->used_in_bytes();
334
335 // Reset our survivor overflow.
336 set_survivor_overflow(false);
337
338 // We need to save the old/perm top values before
339 // creating the promotion_manager. We pass the top
340 // values to the card_table, to prevent it from
341 // straying into the promotion labs.
342 HeapWord* old_top = old_gen->object_space()->top();
343 HeapWord* perm_top = perm_gen->object_space()->top();
344
345 // Release all previously held resources
346 gc_task_manager()->release_all_resources();
347
348 PSPromotionManager::pre_scavenge();
349
350 // We'll use the promotion manager again later.
351 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
352 {
353 // TraceTime("Roots");
354 ParallelScavengeHeap::ParStrongRootsScope psrs;
355
356 GCTaskQueue* q = GCTaskQueue::create();
357
358 for(uint i=0; i<ParallelGCThreads; i++) {
359 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i));
360 }
361
362 q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top));
363
364 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
365 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
366 // We scan the thread roots in parallel
367 Threads::create_thread_roots_tasks(q);
368 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
369 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
370 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
371 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
372 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
373 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
374
375 ParallelTaskTerminator terminator(
376 gc_task_manager()->workers(),
377 (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
378 if (ParallelGCThreads>1) {
379 for (uint j=0; j<ParallelGCThreads; j++) {
380 q->enqueue(new StealTask(&terminator));
381 }
382 }
383
384 gc_task_manager()->execute_and_wait(q);
385 }
386
387 scavenge_midpoint.update();
388
389 // Process reference objects discovered during scavenge
390 {
391 reference_processor()->setup_policy(false); // not always_clear
392 PSKeepAliveClosure keep_alive(promotion_manager);
393 PSEvacuateFollowersClosure evac_followers(promotion_manager);
394 if (reference_processor()->processing_is_mt()) {
395 PSRefProcTaskExecutor task_executor;
396 reference_processor()->process_discovered_references(
397 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor);
398 } else {
399 reference_processor()->process_discovered_references(
400 &_is_alive_closure, &keep_alive, &evac_followers, NULL);
401 }
402 }
403
404 // Enqueue reference objects discovered during scavenge.
405 if (reference_processor()->processing_is_mt()) {
406 PSRefProcTaskExecutor task_executor;
407 reference_processor()->enqueue_discovered_references(&task_executor);
408 } else {
409 reference_processor()->enqueue_discovered_references(NULL);
410 }
411
412 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
413 PSPromotionManager::post_scavenge();
414
415 promotion_failure_occurred = promotion_failed();
416 if (promotion_failure_occurred) {
417 clean_up_failed_promotion();
418 if (PrintGC) {
419 gclog_or_tty->print("--");
420 }
421 }
422
423 // Let the size policy know we're done. Note that we count promotion
424 // failure cleanup time as part of the collection (otherwise, we're
425 // implicitly saying it's mutator time).
426 size_policy->minor_collection_end(gc_cause);
427
428 if (!promotion_failure_occurred) {
429 // Swap the survivor spaces.
430
431
432 young_gen->eden_space()->clear(SpaceDecorator::Mangle);
433 young_gen->from_space()->clear(SpaceDecorator::Mangle);
434 young_gen->swap_spaces();
435
436 size_t survived = young_gen->from_space()->used_in_bytes();
437 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
438 size_policy->update_averages(_survivor_overflow, survived, promoted);
439
440 // A successful scavenge should restart the GC time limit count which is
441 // for full GC's.
442 size_policy->reset_gc_overhead_limit_count();
443 if (UseAdaptiveSizePolicy) {
444 // Calculate the new survivor size and tenuring threshold
445
446 if (PrintAdaptiveSizePolicy) {
447 gclog_or_tty->print("AdaptiveSizeStart: ");
448 gclog_or_tty->stamp();
449 gclog_or_tty->print_cr(" collection: %d ",
450 heap->total_collections());
451
452 if (Verbose) {
453 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
454 " perm_gen_capacity: %d ",
455 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
456 perm_gen->capacity_in_bytes());
457 }
458 }
459
460
461 if (UsePerfData) {
462 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
463 counters->update_old_eden_size(
464 size_policy->calculated_eden_size_in_bytes());
465 counters->update_old_promo_size(
466 size_policy->calculated_promo_size_in_bytes());
467 counters->update_old_capacity(old_gen->capacity_in_bytes());
468 counters->update_young_capacity(young_gen->capacity_in_bytes());
469 counters->update_survived(survived);
470 counters->update_promoted(promoted);
471 counters->update_survivor_overflowed(_survivor_overflow);
472 }
473
474 size_t survivor_limit =
475 size_policy->max_survivor_size(young_gen->max_size());
476 _tenuring_threshold =
477 size_policy->compute_survivor_space_size_and_threshold(
478 _survivor_overflow,
479 _tenuring_threshold,
480 survivor_limit);
481
482 if (PrintTenuringDistribution) {
483 gclog_or_tty->cr();
484 gclog_or_tty->print_cr("Desired survivor size %ld bytes, new threshold %d (max %d)",
485 size_policy->calculated_survivor_size_in_bytes(),
486 _tenuring_threshold, MaxTenuringThreshold);
487 }
488
489 if (UsePerfData) {
490 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
491 counters->update_tenuring_threshold(_tenuring_threshold);
492 counters->update_survivor_size_counters();
493 }
494
495 // Do call at minor collections?
496 // Don't check if the size_policy is ready at this
497 // level. Let the size_policy check that internally.
498 if (UseAdaptiveSizePolicy &&
499 UseAdaptiveGenerationSizePolicyAtMinorCollection &&
500 ((gc_cause != GCCause::_java_lang_system_gc) ||
501 UseAdaptiveSizePolicyWithSystemGC)) {
502
503 // Calculate optimial free space amounts
504 assert(young_gen->max_size() >
505 young_gen->from_space()->capacity_in_bytes() +
506 young_gen->to_space()->capacity_in_bytes(),
507 "Sizes of space in young gen are out-of-bounds");
508 size_t max_eden_size = young_gen->max_size() -
509 young_gen->from_space()->capacity_in_bytes() -
510 young_gen->to_space()->capacity_in_bytes();
511 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
512 young_gen->eden_space()->used_in_bytes(),
513 old_gen->used_in_bytes(),
514 perm_gen->used_in_bytes(),
515 young_gen->eden_space()->capacity_in_bytes(),
516 old_gen->max_gen_size(),
517 max_eden_size,
518 false /* full gc*/,
519 gc_cause,
520 heap->collector_policy());
521
522 }
523 // Resize the young generation at every collection
524 // even if new sizes have not been calculated. This is
525 // to allow resizes that may have been inhibited by the
526 // relative location of the "to" and "from" spaces.
527
528 // Resizing the old gen at minor collects can cause increases
529 // that don't feed back to the generation sizing policy until
530 // a major collection. Don't resize the old gen here.
531
532 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
533 size_policy->calculated_survivor_size_in_bytes());
534
535 if (PrintAdaptiveSizePolicy) {
536 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
537 heap->total_collections());
538 }
539 }
540
541 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
542 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
543 // Also update() will case adaptive NUMA chunk resizing.
544 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
545 young_gen->eden_space()->update();
546
547 heap->gc_policy_counters()->update_counters();
548
549 heap->resize_all_tlabs();
550
551 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
552 }
553
554 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
555
556 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
557
558 // Re-verify object start arrays
559 if (VerifyObjectStartArray &&
560 VerifyAfterGC) {
561 old_gen->verify_object_start_array();
562 perm_gen->verify_object_start_array();
563 }
564
565 // Verify all old -> young cards are now precise
566 if (VerifyRememberedSets) {
567 // Precise verification will give false positives. Until this is fixed,
568 // use imprecise verification.
569 // CardTableExtension::verify_all_young_refs_precise();
570 CardTableExtension::verify_all_young_refs_imprecise();
571 }
572
573 if (TraceGen0Time) accumulated_time()->stop();
574
575 if (PrintGC) {
576 if (PrintGCDetails) {
577 // Don't print a GC timestamp here. This is after the GC so
578 // would be confusing.
579 young_gen->print_used_change(young_gen_used_before);
580 }
581 heap->print_heap_change(prev_used);
582 }
583
584 // Track memory usage and detect low memory
585 MemoryService::track_memory_usage();
586 heap->update_counters();
587 }
588
589 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
590 HandleMark hm; // Discard invalid handles created during verification
591 gclog_or_tty->print(" VerifyAfterGC:");
592 Universe::verify(false);
593 }
594
595 if (PrintHeapAtGC) {
596 Universe::print_heap_after_gc();
597 }
598
599 if (ZapUnusedHeapArea) {
600 young_gen->eden_space()->check_mangled_unused_area_complete();
601 young_gen->from_space()->check_mangled_unused_area_complete();
602 young_gen->to_space()->check_mangled_unused_area_complete();
603 }
604
605 scavenge_exit.update();
606
607 if (PrintGCTaskTimeStamps) {
608 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT,
609 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
610 scavenge_exit.ticks());
611 gc_task_manager()->print_task_time_stamps();
612 }
613
614 #ifdef TRACESPINNING
615 ParallelTaskTerminator::print_termination_counts();
616 #endif
617
618 return !promotion_failure_occurred;
619 }
620
621 // This method iterates over all objects in the young generation,
622 // unforwarding markOops. It then restores any preserved mark oops,
623 // and clears the _preserved_mark_stack.
624 void PSScavenge::clean_up_failed_promotion() {
625 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
626 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
627 assert(promotion_failed(), "Sanity");
628
629 PSYoungGen* young_gen = heap->young_gen();
630
631 {
632 ResourceMark rm;
633
634 // Unforward all pointers in the young gen.
635 PSPromotionFailedClosure unforward_closure;
636 young_gen->object_iterate(&unforward_closure);
637
638 if (PrintGC && Verbose) {
639 gclog_or_tty->print_cr("Restoring %d marks",
640 _preserved_oop_stack->length());
641 }
642
643 // Restore any saved marks.
644 for (int i=0; i < _preserved_oop_stack->length(); i++) {
645 oop obj = _preserved_oop_stack->at(i);
646 markOop mark = _preserved_mark_stack->at(i);
647 obj->set_mark(mark);
648 }
649
650 // Deallocate the preserved mark and oop stacks.
651 // The stacks were allocated as CHeap objects, so
652 // we must call delete to prevent mem leaks.
653 delete _preserved_mark_stack;
654 _preserved_mark_stack = NULL;
655 delete _preserved_oop_stack;
656 _preserved_oop_stack = NULL;
657 }
658
659 // Reset the PromotionFailureALot counters.
660 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
661 }
662
663 // This method is called whenever an attempt to promote an object
664 // fails. Some markOops will need preserving, some will not. Note
665 // that the entire eden is traversed after a failed promotion, with
666 // all forwarded headers replaced by the default markOop. This means
667 // it is not neccessary to preserve most markOops.
668 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
669 if (_preserved_mark_stack == NULL) {
670 ThreadCritical tc; // Lock and retest
671 if (_preserved_mark_stack == NULL) {
672 assert(_preserved_oop_stack == NULL, "Sanity");
673 _preserved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
674 _preserved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
675 }
676 }
677
678 // Because we must hold the ThreadCritical lock before using
679 // the stacks, we should be safe from observing partial allocations,
680 // which are also guarded by the ThreadCritical lock.
681 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
682 ThreadCritical tc;
683 _preserved_oop_stack->push(obj);
684 _preserved_mark_stack->push(obj_mark);
685 }
686 }
687
688 bool PSScavenge::should_attempt_scavenge() {
689 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
690 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
691 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
692
693 if (UsePerfData) {
694 counters->update_scavenge_skipped(not_skipped);
695 }
696
697 PSYoungGen* young_gen = heap->young_gen();
698 PSOldGen* old_gen = heap->old_gen();
699
700 if (!ScavengeWithObjectsInToSpace) {
701 // Do not attempt to promote unless to_space is empty
702 if (!young_gen->to_space()->is_empty()) {
703 _consecutive_skipped_scavenges++;
704 if (UsePerfData) {
705 counters->update_scavenge_skipped(to_space_not_empty);
706 }
707 return false;
708 }
709 }
710
711 // Test to see if the scavenge will likely fail.
712 PSAdaptiveSizePolicy* policy = heap->size_policy();
713
714 // A similar test is done in the policy's should_full_GC(). If this is
715 // changed, decide if that test should also be changed.
716 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
717 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
718 bool result = promotion_estimate < old_gen->free_in_bytes();
719
720 if (PrintGCDetails && Verbose) {
721 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: ");
722 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
723 " padded_average_promoted " SIZE_FORMAT
724 " free in old gen " SIZE_FORMAT,
725 (size_t) policy->average_promoted_in_bytes(),
726 (size_t) policy->padded_average_promoted_in_bytes(),
727 old_gen->free_in_bytes());
728 if (young_gen->used_in_bytes() <
729 (size_t) policy->padded_average_promoted_in_bytes()) {
730 gclog_or_tty->print_cr(" padded_promoted_average is greater"
731 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
732 }
733 }
734
735 if (result) {
736 _consecutive_skipped_scavenges = 0;
737 } else {
738 _consecutive_skipped_scavenges++;
739 if (UsePerfData) {
740 counters->update_scavenge_skipped(promoted_too_large);
741 }
742 }
743 return result;
744 }
745
746 // Used to add tasks
747 GCTaskManager* const PSScavenge::gc_task_manager() {
748 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
749 "shouldn't return NULL");
750 return ParallelScavengeHeap::gc_task_manager();
751 }
752
753 void PSScavenge::initialize() {
754 // Arguments must have been parsed
755
756 if (AlwaysTenure) {
757 _tenuring_threshold = 0;
758 } else if (NeverTenure) {
759 _tenuring_threshold = markOopDesc::max_age + 1;
760 } else {
761 // We want to smooth out our startup times for the AdaptiveSizePolicy
762 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
763 MaxTenuringThreshold;
764 }
765
766 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
767 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
768
769 PSYoungGen* young_gen = heap->young_gen();
770 PSOldGen* old_gen = heap->old_gen();
771 PSPermGen* perm_gen = heap->perm_gen();
772
773 // Set boundary between young_gen and old_gen
774 assert(perm_gen->reserved().end() <= old_gen->object_space()->bottom(),
775 "perm above old");
776 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
777 "old above young");
778 _young_generation_boundary = young_gen->eden_space()->bottom();
779
780 // Initialize ref handling object for scavenging.
781 MemRegion mr = young_gen->reserved();
782 _ref_processor = ReferenceProcessor::create_ref_processor(
783 mr, // span
784 true, // atomic_discovery
785 true, // mt_discovery
786 NULL, // is_alive_non_header
787 ParallelGCThreads,
788 ParallelRefProcEnabled);
789
790 // Cache the cardtable
791 BarrierSet* bs = Universe::heap()->barrier_set();
792 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
793 _card_table = (CardTableExtension*)bs;
794
795 _counters = new CollectorCounters("PSScavenge", 0);
796 }