1/*
2 * Copyright (c) 2001, 2019, 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.
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23 */
24
25#include "precompiled.hpp"
26#include "aot/aotLoader.hpp"
27#include "classfile/classLoaderDataGraph.hpp"
28#include "classfile/stringTable.hpp"
29#include "classfile/symbolTable.hpp"
30#include "classfile/systemDictionary.hpp"
31#include "code/codeCache.hpp"
32#include "gc/parallel/parallelScavengeHeap.hpp"
33#include "gc/parallel/psAdaptiveSizePolicy.hpp"
34#include "gc/parallel/psMarkSweep.hpp"
35#include "gc/parallel/psMarkSweepDecorator.hpp"
36#include "gc/parallel/psOldGen.hpp"
37#include "gc/parallel/psScavenge.hpp"
38#include "gc/parallel/psYoungGen.hpp"
39#include "gc/serial/markSweep.hpp"
40#include "gc/shared/gcCause.hpp"
41#include "gc/shared/gcHeapSummary.hpp"
42#include "gc/shared/gcId.hpp"
43#include "gc/shared/gcLocker.hpp"
44#include "gc/shared/gcTimer.hpp"
45#include "gc/shared/gcTrace.hpp"
46#include "gc/shared/gcTraceTime.inline.hpp"
47#include "gc/shared/isGCActiveMark.hpp"
48#include "gc/shared/referencePolicy.hpp"
49#include "gc/shared/referenceProcessor.hpp"
50#include "gc/shared/referenceProcessorPhaseTimes.hpp"
51#include "gc/shared/spaceDecorator.hpp"
52#include "gc/shared/weakProcessor.hpp"
53#include "memory/universe.hpp"
54#include "logging/log.hpp"
55#include "oops/oop.inline.hpp"
56#include "runtime/biasedLocking.hpp"
57#include "runtime/flags/flagSetting.hpp"
58#include "runtime/handles.inline.hpp"
59#include "runtime/safepoint.hpp"
60#include "runtime/vmThread.hpp"
61#include "services/management.hpp"
62#include "services/memoryService.hpp"
63#include "utilities/align.hpp"
64#include "utilities/events.hpp"
65#include "utilities/stack.inline.hpp"
66#if INCLUDE_JVMCI
67#include "jvmci/jvmci.hpp"
68#endif
69
70elapsedTimer PSMarkSweep::_accumulated_time;
71jlong PSMarkSweep::_time_of_last_gc = 0;
72CollectorCounters* PSMarkSweep::_counters = NULL;
73
74SpanSubjectToDiscoveryClosure PSMarkSweep::_span_based_discoverer;
75
76void PSMarkSweep::initialize() {
77 _span_based_discoverer.set_span(ParallelScavengeHeap::heap()->reserved_region());
78 set_ref_processor(new ReferenceProcessor(&_span_based_discoverer)); // a vanilla ref proc
79 _counters = new CollectorCounters("Serial full collection pauses", 1);
80 MarkSweep::initialize();
81}
82
83// This method contains all heap specific policy for invoking mark sweep.
84// PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
85// the heap. It will do nothing further. If we need to bail out for policy
86// reasons, scavenge before full gc, or any other specialized behavior, it
87// needs to be added here.
88//
89// Note that this method should only be called from the vm_thread while
90// at a safepoint!
91//
92// Note that the all_soft_refs_clear flag in the soft ref policy
93// may be true because this method can be called without intervening
94// activity. For example when the heap space is tight and full measure
95// are being taken to free space.
96
97void PSMarkSweep::invoke(bool maximum_heap_compaction) {
98 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
99 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
100 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
101
102 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
103 GCCause::Cause gc_cause = heap->gc_cause();
104 PSAdaptiveSizePolicy* policy = heap->size_policy();
105 IsGCActiveMark mark;
106
107 if (ScavengeBeforeFullGC) {
108 PSScavenge::invoke_no_policy();
109 }
110
111 const bool clear_all_soft_refs =
112 heap->soft_ref_policy()->should_clear_all_soft_refs();
113
114 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
115 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
116 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
117}
118
119// This method contains no policy. You should probably
120// be calling invoke() instead.
121bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
122 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
123 assert(ref_processor() != NULL, "Sanity");
124
125 if (GCLocker::check_active_before_gc()) {
126 return false;
127 }
128
129 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
130 GCCause::Cause gc_cause = heap->gc_cause();
131
132 GCIdMark gc_id_mark;
133 _gc_timer->register_gc_start();
134 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
135
136 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
137
138 // The scope of casr should end after code that can change
139 // SoftRefolicy::_should_clear_all_soft_refs.
140 ClearedAllSoftRefs casr(clear_all_softrefs, heap->soft_ref_policy());
141
142 PSYoungGen* young_gen = heap->young_gen();
143 PSOldGen* old_gen = heap->old_gen();
144
145 // Increment the invocation count
146 heap->increment_total_collections(true /* full */);
147
148 // Save information needed to minimize mangling
149 heap->record_gen_tops_before_GC();
150
151 // We need to track unique mark sweep invocations as well.
152 _total_invocations++;
153
154 heap->print_heap_before_gc();
155 heap->trace_heap_before_gc(_gc_tracer);
156
157 // Fill in TLABs
158 heap->ensure_parsability(true); // retire TLABs
159
160 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
161 HandleMark hm; // Discard invalid handles created during verification
162 Universe::verify("Before GC");
163 }
164
165 // Verify object start arrays
166 if (VerifyObjectStartArray &&
167 VerifyBeforeGC) {
168 old_gen->verify_object_start_array();
169 }
170
171 // Filled in below to track the state of the young gen after the collection.
172 bool eden_empty;
173 bool survivors_empty;
174 bool young_gen_empty;
175
176 {
177 HandleMark hm;
178
179 GCTraceCPUTime tcpu;
180 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true);
181
182 heap->pre_full_gc_dump(_gc_timer);
183
184 TraceCollectorStats tcs(counters());
185 TraceMemoryManagerStats tms(heap->old_gc_manager(),gc_cause);
186
187 if (log_is_enabled(Debug, gc, heap, exit)) {
188 accumulated_time()->start();
189 }
190
191 // Let the size policy know we're starting
192 size_policy->major_collection_begin();
193
194 BiasedLocking::preserve_marks();
195
196 // Capture metadata size before collection for sizing.
197 size_t metadata_prev_used = MetaspaceUtils::used_bytes();
198
199 size_t old_gen_prev_used = old_gen->used_in_bytes();
200 size_t young_gen_prev_used = young_gen->used_in_bytes();
201
202 allocate_stacks();
203
204#if COMPILER2_OR_JVMCI
205 DerivedPointerTable::clear();
206#endif
207
208 ref_processor()->enable_discovery();
209 ref_processor()->setup_policy(clear_all_softrefs);
210
211 mark_sweep_phase1(clear_all_softrefs);
212
213 mark_sweep_phase2();
214
215#if COMPILER2_OR_JVMCI
216 // Don't add any more derived pointers during phase3
217 assert(DerivedPointerTable::is_active(), "Sanity");
218 DerivedPointerTable::set_active(false);
219#endif
220
221 mark_sweep_phase3();
222
223 mark_sweep_phase4();
224
225 restore_marks();
226
227 deallocate_stacks();
228
229 if (ZapUnusedHeapArea) {
230 // Do a complete mangle (top to end) because the usage for
231 // scratch does not maintain a top pointer.
232 young_gen->to_space()->mangle_unused_area_complete();
233 }
234
235 eden_empty = young_gen->eden_space()->is_empty();
236 if (!eden_empty) {
237 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
238 }
239
240 // Update heap occupancy information which is used as
241 // input to soft ref clearing policy at the next gc.
242 Universe::update_heap_info_at_gc();
243
244 survivors_empty = young_gen->from_space()->is_empty() &&
245 young_gen->to_space()->is_empty();
246 young_gen_empty = eden_empty && survivors_empty;
247
248 PSCardTable* card_table = heap->card_table();
249 MemRegion old_mr = heap->old_gen()->reserved();
250 if (young_gen_empty) {
251 card_table->clear(MemRegion(old_mr.start(), old_mr.end()));
252 } else {
253 card_table->invalidate(MemRegion(old_mr.start(), old_mr.end()));
254 }
255
256 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
257 ClassLoaderDataGraph::purge();
258 MetaspaceUtils::verify_metrics();
259
260 BiasedLocking::restore_marks();
261 heap->prune_scavengable_nmethods();
262 JvmtiExport::gc_epilogue();
263
264#if COMPILER2_OR_JVMCI
265 DerivedPointerTable::update_pointers();
266#endif
267
268 assert(!ref_processor()->discovery_enabled(), "Should have been disabled earlier");
269
270 // Update time of last GC
271 reset_millis_since_last_gc();
272
273 // Let the size policy know we're done
274 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
275
276 if (UseAdaptiveSizePolicy) {
277
278 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
279 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
280 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
281
282 // Don't check if the size_policy is ready here. Let
283 // the size_policy check that internally.
284 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
285 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
286 // Swap the survivor spaces if from_space is empty. The
287 // resize_young_gen() called below is normally used after
288 // a successful young GC and swapping of survivor spaces;
289 // otherwise, it will fail to resize the young gen with
290 // the current implementation.
291 if (young_gen->from_space()->is_empty()) {
292 young_gen->from_space()->clear(SpaceDecorator::Mangle);
293 young_gen->swap_spaces();
294 }
295
296 // Calculate optimal free space amounts
297 assert(young_gen->max_size() >
298 young_gen->from_space()->capacity_in_bytes() +
299 young_gen->to_space()->capacity_in_bytes(),
300 "Sizes of space in young gen are out of bounds");
301
302 size_t young_live = young_gen->used_in_bytes();
303 size_t eden_live = young_gen->eden_space()->used_in_bytes();
304 size_t old_live = old_gen->used_in_bytes();
305 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
306 size_t max_old_gen_size = old_gen->max_gen_size();
307 size_t max_eden_size = young_gen->max_size() -
308 young_gen->from_space()->capacity_in_bytes() -
309 young_gen->to_space()->capacity_in_bytes();
310
311 // Used for diagnostics
312 size_policy->clear_generation_free_space_flags();
313
314 size_policy->compute_generations_free_space(young_live,
315 eden_live,
316 old_live,
317 cur_eden,
318 max_old_gen_size,
319 max_eden_size,
320 true /* full gc*/);
321
322 size_policy->check_gc_overhead_limit(eden_live,
323 max_old_gen_size,
324 max_eden_size,
325 true /* full gc*/,
326 gc_cause,
327 heap->soft_ref_policy());
328
329 size_policy->decay_supplemental_growth(true /* full gc*/);
330
331 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
332
333 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
334 size_policy->calculated_survivor_size_in_bytes());
335 }
336 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
337 }
338
339 if (UsePerfData) {
340 heap->gc_policy_counters()->update_counters();
341 heap->gc_policy_counters()->update_old_capacity(
342 old_gen->capacity_in_bytes());
343 heap->gc_policy_counters()->update_young_capacity(
344 young_gen->capacity_in_bytes());
345 }
346
347 heap->resize_all_tlabs();
348
349 // We collected the heap, recalculate the metaspace capacity
350 MetaspaceGC::compute_new_size();
351
352 if (log_is_enabled(Debug, gc, heap, exit)) {
353 accumulated_time()->stop();
354 }
355
356 young_gen->print_used_change(young_gen_prev_used);
357 old_gen->print_used_change(old_gen_prev_used);
358 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
359
360 // Track memory usage and detect low memory
361 MemoryService::track_memory_usage();
362 heap->update_counters();
363
364 heap->post_full_gc_dump(_gc_timer);
365 }
366
367 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
368 HandleMark hm; // Discard invalid handles created during verification
369 Universe::verify("After GC");
370 }
371
372 // Re-verify object start arrays
373 if (VerifyObjectStartArray &&
374 VerifyAfterGC) {
375 old_gen->verify_object_start_array();
376 }
377
378 if (ZapUnusedHeapArea) {
379 old_gen->object_space()->check_mangled_unused_area_complete();
380 }
381
382 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
383
384 heap->print_heap_after_gc();
385 heap->trace_heap_after_gc(_gc_tracer);
386
387#ifdef TRACESPINNING
388 ParallelTaskTerminator::print_termination_counts();
389#endif
390
391 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
392
393 _gc_timer->register_gc_end();
394
395 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
396
397 return true;
398}
399
400bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
401 PSYoungGen* young_gen,
402 PSOldGen* old_gen) {
403 MutableSpace* const eden_space = young_gen->eden_space();
404 assert(!eden_space->is_empty(), "eden must be non-empty");
405 assert(young_gen->virtual_space()->alignment() ==
406 old_gen->virtual_space()->alignment(), "alignments do not match");
407
408 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
409 return false;
410 }
411
412 // Both generations must be completely committed.
413 if (young_gen->virtual_space()->uncommitted_size() != 0) {
414 return false;
415 }
416 if (old_gen->virtual_space()->uncommitted_size() != 0) {
417 return false;
418 }
419
420 // Figure out how much to take from eden. Include the average amount promoted
421 // in the total; otherwise the next young gen GC will simply bail out to a
422 // full GC.
423 const size_t alignment = old_gen->virtual_space()->alignment();
424 const size_t eden_used = eden_space->used_in_bytes();
425 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
426 const size_t absorb_size = align_up(eden_used + promoted, alignment);
427 const size_t eden_capacity = eden_space->capacity_in_bytes();
428
429 if (absorb_size >= eden_capacity) {
430 return false; // Must leave some space in eden.
431 }
432
433 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
434 if (new_young_size < young_gen->min_gen_size()) {
435 return false; // Respect young gen minimum size.
436 }
437
438 log_trace(gc, ergo, heap)(" absorbing " SIZE_FORMAT "K: "
439 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
440 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
441 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
442 absorb_size / K,
443 eden_capacity / K, (eden_capacity - absorb_size) / K,
444 young_gen->from_space()->used_in_bytes() / K,
445 young_gen->to_space()->used_in_bytes() / K,
446 young_gen->capacity_in_bytes() / K, new_young_size / K);
447
448 // Fill the unused part of the old gen.
449 MutableSpace* const old_space = old_gen->object_space();
450 HeapWord* const unused_start = old_space->top();
451 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
452
453 if (unused_words > 0) {
454 if (unused_words < CollectedHeap::min_fill_size()) {
455 return false; // If the old gen cannot be filled, must give up.
456 }
457 CollectedHeap::fill_with_objects(unused_start, unused_words);
458 }
459
460 // Take the live data from eden and set both top and end in the old gen to
461 // eden top. (Need to set end because reset_after_change() mangles the region
462 // from end to virtual_space->high() in debug builds).
463 HeapWord* const new_top = eden_space->top();
464 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
465 absorb_size);
466 young_gen->reset_after_change();
467 old_space->set_top(new_top);
468 old_space->set_end(new_top);
469 old_gen->reset_after_change();
470
471 // Update the object start array for the filler object and the data from eden.
472 ObjectStartArray* const start_array = old_gen->start_array();
473 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
474 start_array->allocate_block(p);
475 }
476
477 // Could update the promoted average here, but it is not typically updated at
478 // full GCs and the value to use is unclear. Something like
479 //
480 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
481
482 size_policy->set_bytes_absorbed_from_eden(absorb_size);
483 return true;
484}
485
486void PSMarkSweep::allocate_stacks() {
487 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
488 PSYoungGen* young_gen = heap->young_gen();
489
490 MutableSpace* to_space = young_gen->to_space();
491 _preserved_marks = (PreservedMark*)to_space->top();
492 _preserved_count = 0;
493
494 // We want to calculate the size in bytes first.
495 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
496 // Now divide by the size of a PreservedMark
497 _preserved_count_max /= sizeof(PreservedMark);
498}
499
500
501void PSMarkSweep::deallocate_stacks() {
502 _preserved_mark_stack.clear(true);
503 _preserved_oop_stack.clear(true);
504 _marking_stack.clear();
505 _objarray_stack.clear(true);
506}
507
508void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
509 // Recursively traverse all live objects and mark them
510 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer);
511
512 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
513
514 // Need to clear claim bits before the tracing starts.
515 ClassLoaderDataGraph::clear_claimed_marks();
516
517 // General strong roots.
518 {
519 ParallelScavengeHeap::ParStrongRootsScope psrs;
520 Universe::oops_do(mark_and_push_closure());
521 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
522 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
523 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
524 ObjectSynchronizer::oops_do(mark_and_push_closure());
525 Management::oops_do(mark_and_push_closure());
526 JvmtiExport::oops_do(mark_and_push_closure());
527 SystemDictionary::oops_do(mark_and_push_closure());
528 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
529 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
530 //ScavengableNMethods::scavengable_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
531 AOT_ONLY(AOTLoader::oops_do(mark_and_push_closure());)
532 JVMCI_ONLY(JVMCI::oops_do(mark_and_push_closure());)
533 }
534
535 // Flush marking stack.
536 follow_stack();
537
538 // Process reference objects found during marking
539 {
540 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer);
541
542 ref_processor()->setup_policy(clear_all_softrefs);
543 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->max_num_queues());
544 const ReferenceProcessorStats& stats =
545 ref_processor()->process_discovered_references(
546 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, &pt);
547 gc_tracer()->report_gc_reference_stats(stats);
548 pt.print_all_references();
549 }
550
551 // This is the point where the entire marking should have completed.
552 assert(_marking_stack.is_empty(), "Marking should have completed");
553
554 {
555 GCTraceTime(Debug, gc, phases) t("Weak Processing", _gc_timer);
556 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl);
557 }
558
559 {
560 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer);
561
562 // Unload classes and purge the SystemDictionary.
563 bool purged_class = SystemDictionary::do_unloading(_gc_timer);
564
565 // Unload nmethods.
566 CodeCache::do_unloading(is_alive_closure(), purged_class);
567
568 // Prune dead klasses from subklass/sibling/implementor lists.
569 Klass::clean_weak_klass_links(purged_class);
570
571 // Clean JVMCI metadata handles.
572 JVMCI_ONLY(JVMCI::do_unloading(purged_class));
573 }
574
575 _gc_tracer->report_object_count_after_gc(is_alive_closure());
576}
577
578
579void PSMarkSweep::mark_sweep_phase2() {
580 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer);
581
582 // Now all live objects are marked, compute the new object addresses.
583
584 // It is not required that we traverse spaces in the same order in
585 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
586 // tracking expects us to do so. See comment under phase4.
587
588 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
589 PSOldGen* old_gen = heap->old_gen();
590
591 // Begin compacting into the old gen
592 PSMarkSweepDecorator::set_destination_decorator_tenured();
593
594 // This will also compact the young gen spaces.
595 old_gen->precompact();
596}
597
598void PSMarkSweep::mark_sweep_phase3() {
599 // Adjust the pointers to reflect the new locations
600 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer);
601
602 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
603 PSYoungGen* young_gen = heap->young_gen();
604 PSOldGen* old_gen = heap->old_gen();
605
606 // Need to clear claim bits before the tracing starts.
607 ClassLoaderDataGraph::clear_claimed_marks();
608
609 // General strong roots.
610 Universe::oops_do(adjust_pointer_closure());
611 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
612 Threads::oops_do(adjust_pointer_closure(), NULL);
613 ObjectSynchronizer::oops_do(adjust_pointer_closure());
614 Management::oops_do(adjust_pointer_closure());
615 JvmtiExport::oops_do(adjust_pointer_closure());
616 SystemDictionary::oops_do(adjust_pointer_closure());
617 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
618
619 // Now adjust pointers in remaining weak roots. (All of which should
620 // have been cleared if they pointed to non-surviving objects.)
621 // Global (weak) JNI handles
622 WeakProcessor::oops_do(adjust_pointer_closure());
623
624 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
625 CodeCache::blobs_do(&adjust_from_blobs);
626 AOT_ONLY(AOTLoader::oops_do(adjust_pointer_closure());)
627
628 JVMCI_ONLY(JVMCI::oops_do(adjust_pointer_closure());)
629
630 ref_processor()->weak_oops_do(adjust_pointer_closure());
631 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
632
633 adjust_marks();
634
635 young_gen->adjust_pointers();
636 old_gen->adjust_pointers();
637}
638
639void PSMarkSweep::mark_sweep_phase4() {
640 EventMark m("4 compact heap");
641 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer);
642
643 // All pointers are now adjusted, move objects accordingly
644
645 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
646 PSYoungGen* young_gen = heap->young_gen();
647 PSOldGen* old_gen = heap->old_gen();
648
649 old_gen->compact();
650 young_gen->compact();
651}
652
653jlong PSMarkSweep::millis_since_last_gc() {
654 // We need a monotonically non-decreasing time in ms but
655 // os::javaTimeMillis() does not guarantee monotonicity.
656 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
657 jlong ret_val = now - _time_of_last_gc;
658 // XXX See note in genCollectedHeap::millis_since_last_gc().
659 if (ret_val < 0) {
660 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
661 return 0;
662 }
663 return ret_val;
664}
665
666void PSMarkSweep::reset_millis_since_last_gc() {
667 // We need a monotonically non-decreasing time in ms but
668 // os::javaTimeMillis() does not guarantee monotonicity.
669 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
670}
671