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.
22 *
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
70 elapsedTimer PSMarkSweep::_accumulated_time;
71 jlong PSMarkSweep::_time_of_last_gc = 0;
72 CollectorCounters* PSMarkSweep::_counters = NULL;
73
74 SpanSubjectToDiscoveryClosure PSMarkSweep::_span_based_discoverer;
75
76 void 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
97 void 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.
121 bool 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 const PreGCValues pre_gc_values(heap);
197
198 allocate_stacks();
199
200 #if COMPILER2_OR_JVMCI
201 DerivedPointerTable::clear();
202 #endif
203
204 ref_processor()->enable_discovery();
205 ref_processor()->setup_policy(clear_all_softrefs);
206
207 mark_sweep_phase1(clear_all_softrefs);
208
209 mark_sweep_phase2();
210
211 #if COMPILER2_OR_JVMCI
212 // Don't add any more derived pointers during phase3
213 assert(DerivedPointerTable::is_active(), "Sanity");
214 DerivedPointerTable::set_active(false);
215 #endif
216
217 mark_sweep_phase3();
218
219 mark_sweep_phase4();
220
221 restore_marks();
222
223 deallocate_stacks();
224
225 if (ZapUnusedHeapArea) {
226 // Do a complete mangle (top to end) because the usage for
227 // scratch does not maintain a top pointer.
228 young_gen->to_space()->mangle_unused_area_complete();
229 }
230
231 eden_empty = young_gen->eden_space()->is_empty();
232 if (!eden_empty) {
233 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
234 }
235
236 // Update heap occupancy information which is used as
237 // input to soft ref clearing policy at the next gc.
238 Universe::update_heap_info_at_gc();
239
240 survivors_empty = young_gen->from_space()->is_empty() &&
241 young_gen->to_space()->is_empty();
242 young_gen_empty = eden_empty && survivors_empty;
243
244 PSCardTable* card_table = heap->card_table();
245 MemRegion old_mr = heap->old_gen()->reserved();
246 if (young_gen_empty) {
247 card_table->clear(MemRegion(old_mr.start(), old_mr.end()));
248 } else {
249 card_table->invalidate(MemRegion(old_mr.start(), old_mr.end()));
250 }
251
252 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
253 ClassLoaderDataGraph::purge();
254 DEBUG_ONLY(MetaspaceUtils::verify(false);)
255
256 BiasedLocking::restore_marks();
257 heap->prune_scavengable_nmethods();
258
259 #if COMPILER2_OR_JVMCI
260 DerivedPointerTable::update_pointers();
261 #endif
262
263 assert(!ref_processor()->discovery_enabled(), "Should have been disabled earlier");
264
265 // Update time of last GC
266 reset_millis_since_last_gc();
267
268 // Let the size policy know we're done
269 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
270
271 if (UseAdaptiveSizePolicy) {
272
273 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
274 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
275 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
276
277 // Don't check if the size_policy is ready here. Let
278 // the size_policy check that internally.
279 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
280 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
281 // Swap the survivor spaces if from_space is empty. The
282 // resize_young_gen() called below is normally used after
283 // a successful young GC and swapping of survivor spaces;
284 // otherwise, it will fail to resize the young gen with
285 // the current implementation.
286 if (young_gen->from_space()->is_empty()) {
287 young_gen->from_space()->clear(SpaceDecorator::Mangle);
288 young_gen->swap_spaces();
289 }
290
291 // Calculate optimal free space amounts
292 assert(young_gen->max_size() >
293 young_gen->from_space()->capacity_in_bytes() +
294 young_gen->to_space()->capacity_in_bytes(),
295 "Sizes of space in young gen are out of bounds");
296
297 size_t young_live = young_gen->used_in_bytes();
298 size_t eden_live = young_gen->eden_space()->used_in_bytes();
299 size_t old_live = old_gen->used_in_bytes();
300 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
301 size_t max_old_gen_size = old_gen->max_gen_size();
302 size_t max_eden_size = young_gen->max_size() -
303 young_gen->from_space()->capacity_in_bytes() -
304 young_gen->to_space()->capacity_in_bytes();
305
306 // Used for diagnostics
307 size_policy->clear_generation_free_space_flags();
308
309 size_policy->compute_generations_free_space(young_live,
310 eden_live,
311 old_live,
312 cur_eden,
313 max_old_gen_size,
314 max_eden_size,
315 true /* full gc*/);
316
317 size_policy->check_gc_overhead_limit(eden_live,
318 max_old_gen_size,
319 max_eden_size,
320 true /* full gc*/,
321 gc_cause,
322 heap->soft_ref_policy());
323
324 size_policy->decay_supplemental_growth(true /* full gc*/);
325
326 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
327
328 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
329 size_policy->calculated_survivor_size_in_bytes());
330 }
331 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
332 }
333
334 if (UsePerfData) {
335 heap->gc_policy_counters()->update_counters();
336 heap->gc_policy_counters()->update_old_capacity(
337 old_gen->capacity_in_bytes());
338 heap->gc_policy_counters()->update_young_capacity(
339 young_gen->capacity_in_bytes());
340 }
341
342 heap->resize_all_tlabs();
343
344 // We collected the heap, recalculate the metaspace capacity
345 MetaspaceGC::compute_new_size();
346
347 if (log_is_enabled(Debug, gc, heap, exit)) {
348 accumulated_time()->stop();
349 }
350
351 young_gen->print_used_change(pre_gc_values.young_gen_used());
352 old_gen->print_used_change(pre_gc_values.old_gen_used());
353 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
354
355 // Track memory usage and detect low memory
356 MemoryService::track_memory_usage();
357 heap->update_counters();
358
359 heap->post_full_gc_dump(_gc_timer);
360 }
361
362 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
363 HandleMark hm; // Discard invalid handles created during verification
364 Universe::verify("After GC");
365 }
366
367 // Re-verify object start arrays
368 if (VerifyObjectStartArray &&
369 VerifyAfterGC) {
370 old_gen->verify_object_start_array();
371 }
372
373 if (ZapUnusedHeapArea) {
374 old_gen->object_space()->check_mangled_unused_area_complete();
375 }
376
377 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
378
379 heap->print_heap_after_gc();
380 heap->trace_heap_after_gc(_gc_tracer);
381
382 #ifdef TRACESPINNING
383 ParallelTaskTerminator::print_termination_counts();
384 #endif
385
386 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
387
388 _gc_timer->register_gc_end();
389
390 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
391
392 return true;
393 }
394
395 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
396 PSYoungGen* young_gen,
397 PSOldGen* old_gen) {
398 MutableSpace* const eden_space = young_gen->eden_space();
399 assert(!eden_space->is_empty(), "eden must be non-empty");
400 assert(young_gen->virtual_space()->alignment() ==
401 old_gen->virtual_space()->alignment(), "alignments do not match");
402
403 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
404 return false;
405 }
406
407 // Both generations must be completely committed.
408 if (young_gen->virtual_space()->uncommitted_size() != 0) {
409 return false;
410 }
411 if (old_gen->virtual_space()->uncommitted_size() != 0) {
412 return false;
413 }
414
415 // Figure out how much to take from eden. Include the average amount promoted
416 // in the total; otherwise the next young gen GC will simply bail out to a
417 // full GC.
418 const size_t alignment = old_gen->virtual_space()->alignment();
419 const size_t eden_used = eden_space->used_in_bytes();
420 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
421 const size_t absorb_size = align_up(eden_used + promoted, alignment);
422 const size_t eden_capacity = eden_space->capacity_in_bytes();
423
424 if (absorb_size >= eden_capacity) {
425 return false; // Must leave some space in eden.
426 }
427
428 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
429 if (new_young_size < young_gen->min_gen_size()) {
430 return false; // Respect young gen minimum size.
431 }
432
433 log_trace(gc, ergo, heap)(" absorbing " SIZE_FORMAT "K: "
434 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
435 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
436 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
437 absorb_size / K,
438 eden_capacity / K, (eden_capacity - absorb_size) / K,
439 young_gen->from_space()->used_in_bytes() / K,
440 young_gen->to_space()->used_in_bytes() / K,
441 young_gen->capacity_in_bytes() / K, new_young_size / K);
442
443 // Fill the unused part of the old gen.
444 MutableSpace* const old_space = old_gen->object_space();
445 HeapWord* const unused_start = old_space->top();
446 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
447
448 if (unused_words > 0) {
449 if (unused_words < CollectedHeap::min_fill_size()) {
450 return false; // If the old gen cannot be filled, must give up.
451 }
452 CollectedHeap::fill_with_objects(unused_start, unused_words);
453 }
454
455 // Take the live data from eden and set both top and end in the old gen to
456 // eden top. (Need to set end because reset_after_change() mangles the region
457 // from end to virtual_space->high() in debug builds).
458 HeapWord* const new_top = eden_space->top();
459 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
460 absorb_size);
461 young_gen->reset_after_change();
462 old_space->set_top(new_top);
463 old_space->set_end(new_top);
464 old_gen->reset_after_change();
465
466 // Update the object start array for the filler object and the data from eden.
467 ObjectStartArray* const start_array = old_gen->start_array();
468 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
469 start_array->allocate_block(p);
470 }
471
472 // Could update the promoted average here, but it is not typically updated at
473 // full GCs and the value to use is unclear. Something like
474 //
475 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
476
477 size_policy->set_bytes_absorbed_from_eden(absorb_size);
478 return true;
479 }
480
481 void PSMarkSweep::allocate_stacks() {
482 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
483 PSYoungGen* young_gen = heap->young_gen();
484
485 MutableSpace* to_space = young_gen->to_space();
486 _preserved_marks = (PreservedMark*)to_space->top();
487 _preserved_count = 0;
488
489 // We want to calculate the size in bytes first.
490 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
491 // Now divide by the size of a PreservedMark
492 _preserved_count_max /= sizeof(PreservedMark);
493 }
494
495
496 void PSMarkSweep::deallocate_stacks() {
497 _preserved_mark_stack.clear(true);
498 _preserved_oop_stack.clear(true);
499 _marking_stack.clear();
500 _objarray_stack.clear(true);
501 }
502
503 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
504 // Recursively traverse all live objects and mark them
505 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer);
506
507 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
508
509 // Need to clear claim bits before the tracing starts.
510 ClassLoaderDataGraph::clear_claimed_marks();
511
512 // General strong roots.
513 {
514 ParallelScavengeHeap::ParStrongRootsScope psrs;
515 Universe::oops_do(mark_and_push_closure());
516 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
517 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
518 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
519 ObjectSynchronizer::oops_do(mark_and_push_closure());
520 Management::oops_do(mark_and_push_closure());
521 JvmtiExport::oops_do(mark_and_push_closure());
522 SystemDictionary::oops_do(mark_and_push_closure());
523 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
524 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
525 //ScavengableNMethods::scavengable_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
526 AOT_ONLY(AOTLoader::oops_do(mark_and_push_closure());)
527 }
528
529 // Flush marking stack.
530 follow_stack();
531
532 // Process reference objects found during marking
533 {
534 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer);
535
536 ref_processor()->setup_policy(clear_all_softrefs);
537 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->max_num_queues());
538 const ReferenceProcessorStats& stats =
539 ref_processor()->process_discovered_references(
540 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, &pt);
541 gc_tracer()->report_gc_reference_stats(stats);
542 pt.print_all_references();
543 }
544
545 // This is the point where the entire marking should have completed.
546 assert(_marking_stack.is_empty(), "Marking should have completed");
547
548 {
549 GCTraceTime(Debug, gc, phases) t("Weak Processing", _gc_timer);
550 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl);
551 }
552
553 {
554 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer);
555
556 // Unload classes and purge the SystemDictionary.
557 bool purged_class = SystemDictionary::do_unloading(_gc_timer);
558
559 // Unload nmethods.
560 CodeCache::do_unloading(is_alive_closure(), purged_class);
561
562 // Prune dead klasses from subklass/sibling/implementor lists.
563 Klass::clean_weak_klass_links(purged_class);
564
565 // Clean JVMCI metadata handles.
566 JVMCI_ONLY(JVMCI::do_unloading(purged_class));
567 }
568
569 _gc_tracer->report_object_count_after_gc(is_alive_closure());
570 }
571
572
573 void PSMarkSweep::mark_sweep_phase2() {
574 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer);
575
576 // Now all live objects are marked, compute the new object addresses.
577
578 // It is not required that we traverse spaces in the same order in
579 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
580 // tracking expects us to do so. See comment under phase4.
581
582 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
583 PSOldGen* old_gen = heap->old_gen();
584
585 // Begin compacting into the old gen
586 PSMarkSweepDecorator::set_destination_decorator_tenured();
587
588 // This will also compact the young gen spaces.
589 old_gen->precompact();
590 }
591
592 void PSMarkSweep::mark_sweep_phase3() {
593 // Adjust the pointers to reflect the new locations
594 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer);
595
596 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
597 PSYoungGen* young_gen = heap->young_gen();
598 PSOldGen* old_gen = heap->old_gen();
599
600 // Need to clear claim bits before the tracing starts.
601 ClassLoaderDataGraph::clear_claimed_marks();
602
603 // General strong roots.
604 Universe::oops_do(adjust_pointer_closure());
605 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
606 Threads::oops_do(adjust_pointer_closure(), NULL);
607 ObjectSynchronizer::oops_do(adjust_pointer_closure());
608 Management::oops_do(adjust_pointer_closure());
609 JvmtiExport::oops_do(adjust_pointer_closure());
610 SystemDictionary::oops_do(adjust_pointer_closure());
611 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
612
613 // Now adjust pointers in remaining weak roots. (All of which should
614 // have been cleared if they pointed to non-surviving objects.)
615 // Global (weak) JNI handles
616 WeakProcessor::oops_do(adjust_pointer_closure());
617
618 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
619 CodeCache::blobs_do(&adjust_from_blobs);
620 AOT_ONLY(AOTLoader::oops_do(adjust_pointer_closure());)
621
622 ref_processor()->weak_oops_do(adjust_pointer_closure());
623 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
624
625 adjust_marks();
626
627 young_gen->adjust_pointers();
628 old_gen->adjust_pointers();
629 }
630
631 void PSMarkSweep::mark_sweep_phase4() {
632 EventMark m("4 compact heap");
633 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer);
634
635 // All pointers are now adjusted, move objects accordingly
636
637 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
638 PSYoungGen* young_gen = heap->young_gen();
639 PSOldGen* old_gen = heap->old_gen();
640
641 old_gen->compact();
642 young_gen->compact();
643 }
644
645 jlong PSMarkSweep::millis_since_last_gc() {
646 // We need a monotonically non-decreasing time in ms but
647 // os::javaTimeMillis() does not guarantee monotonicity.
648 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
649 jlong ret_val = now - _time_of_last_gc;
650 // XXX See note in genCollectedHeap::millis_since_last_gc().
651 if (ret_val < 0) {
652 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
653 return 0;
654 }
655 return ret_val;
656 }
657
658 void PSMarkSweep::reset_millis_since_last_gc() {
659 // We need a monotonically non-decreasing time in ms but
660 // os::javaTimeMillis() does not guarantee monotonicity.
661 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
662 }