1 /*
2 * Copyright (c) 2001, 2018, 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/fill.hpp"
41 #include "gc/shared/gcCause.hpp"
42 #include "gc/shared/gcHeapSummary.hpp"
43 #include "gc/shared/gcId.hpp"
44 #include "gc/shared/gcLocker.hpp"
45 #include "gc/shared/gcTimer.hpp"
46 #include "gc/shared/gcTrace.hpp"
47 #include "gc/shared/gcTraceTime.inline.hpp"
48 #include "gc/shared/isGCActiveMark.hpp"
49 #include "gc/shared/referencePolicy.hpp"
50 #include "gc/shared/referenceProcessor.hpp"
51 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
52 #include "gc/shared/spaceDecorator.hpp"
53 #include "gc/shared/weakProcessor.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
67 elapsedTimer PSMarkSweep::_accumulated_time;
68 jlong PSMarkSweep::_time_of_last_gc = 0;
69 CollectorCounters* PSMarkSweep::_counters = NULL;
70
71 SpanSubjectToDiscoveryClosure PSMarkSweep::_span_based_discoverer;
72
73 void PSMarkSweep::initialize() {
74 _span_based_discoverer.set_span(ParallelScavengeHeap::heap()->reserved_region());
75 set_ref_processor(new ReferenceProcessor(&_span_based_discoverer)); // a vanilla ref proc
76 _counters = new CollectorCounters("PSMarkSweep", 1);
77 MarkSweep::initialize();
78 }
79
80 // This method contains all heap specific policy for invoking mark sweep.
81 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
82 // the heap. It will do nothing further. If we need to bail out for policy
83 // reasons, scavenge before full gc, or any other specialized behavior, it
84 // needs to be added here.
85 //
86 // Note that this method should only be called from the vm_thread while
87 // at a safepoint!
88 //
89 // Note that the all_soft_refs_clear flag in the collector policy
90 // may be true because this method can be called without intervening
91 // activity. For example when the heap space is tight and full measure
92 // are being taken to free space.
93
94 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
95 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
96 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
97 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
98
99 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
100 GCCause::Cause gc_cause = heap->gc_cause();
101 PSAdaptiveSizePolicy* policy = heap->size_policy();
102 IsGCActiveMark mark;
103
104 if (ScavengeBeforeFullGC) {
105 PSScavenge::invoke_no_policy();
106 }
107
108 const bool clear_all_soft_refs =
109 heap->soft_ref_policy()->should_clear_all_soft_refs();
110
111 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
112 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
113 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
114 }
115
116 // This method contains no policy. You should probably
117 // be calling invoke() instead.
118 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
119 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
120 assert(ref_processor() != NULL, "Sanity");
121
122 if (GCLocker::check_active_before_gc()) {
123 return false;
124 }
125
126 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
127 GCCause::Cause gc_cause = heap->gc_cause();
128
129 GCIdMark gc_id_mark;
130 _gc_timer->register_gc_start();
131 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
132
133 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
134
135 // The scope of casr should end after code that can change
136 // CollectorPolicy::_should_clear_all_soft_refs.
137 ClearedAllSoftRefs casr(clear_all_softrefs, heap->soft_ref_policy());
138
139 PSYoungGen* young_gen = heap->young_gen();
140 PSOldGen* old_gen = heap->old_gen();
141
142 // Increment the invocation count
143 heap->increment_total_collections(true /* full */);
144
145 // Save information needed to minimize mangling
146 heap->record_gen_tops_before_GC();
147
148 // We need to track unique mark sweep invocations as well.
149 _total_invocations++;
150
151 heap->print_heap_before_gc();
152 heap->trace_heap_before_gc(_gc_tracer);
153
154 // Fill in TLABs
155 heap->ensure_parsability(true); // retire TLABs
156
157 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
158 HandleMark hm; // Discard invalid handles created during verification
159 Universe::verify("Before GC");
160 }
161
162 // Verify object start arrays
163 if (VerifyObjectStartArray &&
164 VerifyBeforeGC) {
165 old_gen->verify_object_start_array();
166 }
167
168 // Filled in below to track the state of the young gen after the collection.
169 bool eden_empty;
170 bool survivors_empty;
171 bool young_gen_empty;
172
173 {
174 HandleMark hm;
175
176 GCTraceCPUTime tcpu;
177 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true);
178
179 heap->pre_full_gc_dump(_gc_timer);
180
181 TraceCollectorStats tcs(counters());
182 TraceMemoryManagerStats tms(heap->old_gc_manager(),gc_cause);
183
184 if (log_is_enabled(Debug, gc, heap, exit)) {
185 accumulated_time()->start();
186 }
187
188 // Let the size policy know we're starting
189 size_policy->major_collection_begin();
190
191 CodeCache::gc_prologue();
192 BiasedLocking::preserve_marks();
193
194 // Capture metadata size before collection for sizing.
195 size_t metadata_prev_used = MetaspaceUtils::used_bytes();
196
197 size_t old_gen_prev_used = old_gen->used_in_bytes();
198 size_t young_gen_prev_used = young_gen->used_in_bytes();
199
200 allocate_stacks();
201
202 #if COMPILER2_OR_JVMCI
203 DerivedPointerTable::clear();
204 #endif
205
206 ref_processor()->enable_discovery();
207 ref_processor()->setup_policy(clear_all_softrefs);
208
209 mark_sweep_phase1(clear_all_softrefs);
210
211 mark_sweep_phase2();
212
213 #if COMPILER2_OR_JVMCI
214 // Don't add any more derived pointers during phase3
215 assert(DerivedPointerTable::is_active(), "Sanity");
216 DerivedPointerTable::set_active(false);
217 #endif
218
219 mark_sweep_phase3();
220
221 mark_sweep_phase4();
222
223 restore_marks();
224
225 deallocate_stacks();
226
227 if (ZapUnusedHeapArea) {
228 // Do a complete mangle (top to end) because the usage for
229 // scratch does not maintain a top pointer.
230 young_gen->to_space()->mangle_unused_area_complete();
231 }
232
233 eden_empty = young_gen->eden_space()->is_empty();
234 if (!eden_empty) {
235 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
236 }
237
238 // Update heap occupancy information which is used as
239 // input to soft ref clearing policy at the next gc.
240 Universe::update_heap_info_at_gc();
241
242 survivors_empty = young_gen->from_space()->is_empty() &&
243 young_gen->to_space()->is_empty();
244 young_gen_empty = eden_empty && survivors_empty;
245
246 PSCardTable* card_table = heap->card_table();
247 MemRegion old_mr = heap->old_gen()->reserved();
248 if (young_gen_empty) {
249 card_table->clear(MemRegion(old_mr.start(), old_mr.end()));
250 } else {
251 card_table->invalidate(MemRegion(old_mr.start(), old_mr.end()));
252 }
253
254 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
255 ClassLoaderDataGraph::purge();
256 MetaspaceUtils::verify_metrics();
257
258 BiasedLocking::restore_marks();
259 CodeCache::gc_epilogue();
260 JvmtiExport::gc_epilogue();
261
262 #if COMPILER2_OR_JVMCI
263 DerivedPointerTable::update_pointers();
264 #endif
265
266 assert(!ref_processor()->discovery_enabled(), "Should have been disabled earlier");
267
268 // Update time of last GC
269 reset_millis_since_last_gc();
270
271 // Let the size policy know we're done
272 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
273
274 if (UseAdaptiveSizePolicy) {
275
276 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
277 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
278 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
279
280 // Don't check if the size_policy is ready here. Let
281 // the size_policy check that internally.
282 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
283 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
284 // Swap the survivor spaces if from_space is empty. The
285 // resize_young_gen() called below is normally used after
286 // a successful young GC and swapping of survivor spaces;
287 // otherwise, it will fail to resize the young gen with
288 // the current implementation.
289 if (young_gen->from_space()->is_empty()) {
290 young_gen->from_space()->clear(SpaceDecorator::Mangle);
291 young_gen->swap_spaces();
292 }
293
294 // Calculate optimal free space amounts
295 assert(young_gen->max_size() >
296 young_gen->from_space()->capacity_in_bytes() +
297 young_gen->to_space()->capacity_in_bytes(),
298 "Sizes of space in young gen are out of bounds");
299
300 size_t young_live = young_gen->used_in_bytes();
301 size_t eden_live = young_gen->eden_space()->used_in_bytes();
302 size_t old_live = old_gen->used_in_bytes();
303 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
304 size_t max_old_gen_size = old_gen->max_gen_size();
305 size_t max_eden_size = young_gen->max_size() -
306 young_gen->from_space()->capacity_in_bytes() -
307 young_gen->to_space()->capacity_in_bytes();
308
309 // Used for diagnostics
310 size_policy->clear_generation_free_space_flags();
311
312 size_policy->compute_generations_free_space(young_live,
313 eden_live,
314 old_live,
315 cur_eden,
316 max_old_gen_size,
317 max_eden_size,
318 true /* full gc*/);
319
320 size_policy->check_gc_overhead_limit(young_live,
321 eden_live,
322 max_old_gen_size,
323 max_eden_size,
324 true /* full gc*/,
325 gc_cause,
326 heap->soft_ref_policy());
327
328 size_policy->decay_supplemental_growth(true /* full gc*/);
329
330 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
331
332 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
333 size_policy->calculated_survivor_size_in_bytes());
334 }
335 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
336 }
337
338 if (UsePerfData) {
339 heap->gc_policy_counters()->update_counters();
340 heap->gc_policy_counters()->update_old_capacity(
341 old_gen->capacity_in_bytes());
342 heap->gc_policy_counters()->update_young_capacity(
343 young_gen->capacity_in_bytes());
344 }
345
346 heap->resize_all_tlabs();
347
348 // We collected the heap, recalculate the metaspace capacity
349 MetaspaceGC::compute_new_size();
350
351 if (log_is_enabled(Debug, gc, heap, exit)) {
352 accumulated_time()->stop();
353 }
354
355 young_gen->print_used_change(young_gen_prev_used);
356 old_gen->print_used_change(old_gen_prev_used);
357 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
358
359 // Track memory usage and detect low memory
360 MemoryService::track_memory_usage();
361 heap->update_counters();
362
363 heap->post_full_gc_dump(_gc_timer);
364 }
365
366 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
367 HandleMark hm; // Discard invalid handles created during verification
368 Universe::verify("After GC");
369 }
370
371 // Re-verify object start arrays
372 if (VerifyObjectStartArray &&
373 VerifyAfterGC) {
374 old_gen->verify_object_start_array();
375 }
376
377 if (ZapUnusedHeapArea) {
378 old_gen->object_space()->check_mangled_unused_area_complete();
379 }
380
381 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
382
383 heap->print_heap_after_gc();
384 heap->trace_heap_after_gc(_gc_tracer);
385
386 #ifdef TRACESPINNING
387 ParallelTaskTerminator::print_termination_counts();
388 #endif
389
390 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
391
392 _gc_timer->register_gc_end();
393
394 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
395
396 return true;
397 }
398
399 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
400 PSYoungGen* young_gen,
401 PSOldGen* old_gen) {
402 MutableSpace* const eden_space = young_gen->eden_space();
403 assert(!eden_space->is_empty(), "eden must be non-empty");
404 assert(young_gen->virtual_space()->alignment() ==
405 old_gen->virtual_space()->alignment(), "alignments do not match");
406
407 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
408 return false;
409 }
410
411 // Both generations must be completely committed.
412 if (young_gen->virtual_space()->uncommitted_size() != 0) {
413 return false;
414 }
415 if (old_gen->virtual_space()->uncommitted_size() != 0) {
416 return false;
417 }
418
419 // Figure out how much to take from eden. Include the average amount promoted
420 // in the total; otherwise the next young gen GC will simply bail out to a
421 // full GC.
422 const size_t alignment = old_gen->virtual_space()->alignment();
423 const size_t eden_used = eden_space->used_in_bytes();
424 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
425 const size_t absorb_size = align_up(eden_used + promoted, alignment);
426 const size_t eden_capacity = eden_space->capacity_in_bytes();
427
428 if (absorb_size >= eden_capacity) {
429 return false; // Must leave some space in eden.
430 }
431
432 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
433 if (new_young_size < young_gen->min_gen_size()) {
434 return false; // Respect young gen minimum size.
435 }
436
437 log_trace(gc, ergo, heap)(" absorbing " SIZE_FORMAT "K: "
438 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
439 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
440 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
441 absorb_size / K,
442 eden_capacity / K, (eden_capacity - absorb_size) / K,
443 young_gen->from_space()->used_in_bytes() / K,
444 young_gen->to_space()->used_in_bytes() / K,
445 young_gen->capacity_in_bytes() / K, new_young_size / K);
446
447 // Fill the unused part of the old gen.
448 MutableSpace* const old_space = old_gen->object_space();
449 HeapWord* const unused_start = old_space->top();
450 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
451
452 if (unused_words > 0) {
453 if (unused_words < Fill::min_size()) {
454 return false; // If the old gen cannot be filled, must give up.
455 }
456 Fill::range(unused_start, unused_words);
457 }
458
459 // Take the live data from eden and set both top and end in the old gen to
460 // eden top. (Need to set end because reset_after_change() mangles the region
461 // from end to virtual_space->high() in debug builds).
462 HeapWord* const new_top = eden_space->top();
463 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
464 absorb_size);
465 young_gen->reset_after_change();
466 old_space->set_top(new_top);
467 old_space->set_end(new_top);
468 old_gen->reset_after_change();
469
470 // Update the object start array for the filler object and the data from eden.
471 ObjectStartArray* const start_array = old_gen->start_array();
472 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
473 start_array->allocate_block(p);
474 }
475
476 // Could update the promoted average here, but it is not typically updated at
477 // full GCs and the value to use is unclear. Something like
478 //
479 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
480
481 size_policy->set_bytes_absorbed_from_eden(absorb_size);
482 return true;
483 }
484
485 void PSMarkSweep::allocate_stacks() {
486 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
487 PSYoungGen* young_gen = heap->young_gen();
488
489 MutableSpace* to_space = young_gen->to_space();
490 _preserved_marks = (PreservedMark*)to_space->top();
491 _preserved_count = 0;
492
493 // We want to calculate the size in bytes first.
494 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
495 // Now divide by the size of a PreservedMark
496 _preserved_count_max /= sizeof(PreservedMark);
497 }
498
499
500 void PSMarkSweep::deallocate_stacks() {
501 _preserved_mark_stack.clear(true);
502 _preserved_oop_stack.clear(true);
503 _marking_stack.clear();
504 _objarray_stack.clear(true);
505 }
506
507 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
508 // Recursively traverse all live objects and mark them
509 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer);
510
511 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
512
513 // Need to clear claim bits before the tracing starts.
514 ClassLoaderDataGraph::clear_claimed_marks();
515
516 // General strong roots.
517 {
518 ParallelScavengeHeap::ParStrongRootsScope psrs;
519 Universe::oops_do(mark_and_push_closure());
520 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
521 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
522 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
523 ObjectSynchronizer::oops_do(mark_and_push_closure());
524 Management::oops_do(mark_and_push_closure());
525 JvmtiExport::oops_do(mark_and_push_closure());
526 SystemDictionary::oops_do(mark_and_push_closure());
527 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
528 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
529 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
530 AOTLoader::oops_do(mark_and_push_closure());
531 }
532
533 // Flush marking stack.
534 follow_stack();
535
536 // Process reference objects found during marking
537 {
538 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer);
539
540 ref_processor()->setup_policy(clear_all_softrefs);
541 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->max_num_queues());
542 const ReferenceProcessorStats& stats =
543 ref_processor()->process_discovered_references(
544 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, &pt);
545 gc_tracer()->report_gc_reference_stats(stats);
546 pt.print_all_references();
547 }
548
549 // This is the point where the entire marking should have completed.
550 assert(_marking_stack.is_empty(), "Marking should have completed");
551
552 {
553 GCTraceTime(Debug, gc, phases) t("Weak Processing", _gc_timer);
554 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl);
555 }
556
557 {
558 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer);
559
560 // Unload classes and purge the SystemDictionary.
561 bool purged_class = SystemDictionary::do_unloading(_gc_timer);
562
563 // Unload nmethods.
564 CodeCache::do_unloading(is_alive_closure(), purged_class);
565
566 // Prune dead klasses from subklass/sibling/implementor lists.
567 Klass::clean_weak_klass_links(purged_class);
568 }
569
570 {
571 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer);
572 // Delete entries for dead interned strings.
573 StringTable::unlink(is_alive_closure());
574 }
575
576 {
577 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer);
578 // Clean up unreferenced symbols in symbol table.
579 SymbolTable::unlink();
580 }
581
582 _gc_tracer->report_object_count_after_gc(is_alive_closure());
583 }
584
585
586 void PSMarkSweep::mark_sweep_phase2() {
587 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer);
588
589 // Now all live objects are marked, compute the new object addresses.
590
591 // It is not required that we traverse spaces in the same order in
592 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
593 // tracking expects us to do so. See comment under phase4.
594
595 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
596 PSOldGen* old_gen = heap->old_gen();
597
598 // Begin compacting into the old gen
599 PSMarkSweepDecorator::set_destination_decorator_tenured();
600
601 // This will also compact the young gen spaces.
602 old_gen->precompact();
603 }
604
605 void PSMarkSweep::mark_sweep_phase3() {
606 // Adjust the pointers to reflect the new locations
607 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer);
608
609 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
610 PSYoungGen* young_gen = heap->young_gen();
611 PSOldGen* old_gen = heap->old_gen();
612
613 // Need to clear claim bits before the tracing starts.
614 ClassLoaderDataGraph::clear_claimed_marks();
615
616 // General strong roots.
617 Universe::oops_do(adjust_pointer_closure());
618 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
619 Threads::oops_do(adjust_pointer_closure(), NULL);
620 ObjectSynchronizer::oops_do(adjust_pointer_closure());
621 Management::oops_do(adjust_pointer_closure());
622 JvmtiExport::oops_do(adjust_pointer_closure());
623 SystemDictionary::oops_do(adjust_pointer_closure());
624 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
625
626 // Now adjust pointers in remaining weak roots. (All of which should
627 // have been cleared if they pointed to non-surviving objects.)
628 // Global (weak) JNI handles
629 WeakProcessor::oops_do(adjust_pointer_closure());
630
631 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
632 CodeCache::blobs_do(&adjust_from_blobs);
633 AOTLoader::oops_do(adjust_pointer_closure());
634 StringTable::oops_do(adjust_pointer_closure());
635 ref_processor()->weak_oops_do(adjust_pointer_closure());
636 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
637
638 adjust_marks();
639
640 young_gen->adjust_pointers();
641 old_gen->adjust_pointers();
642 }
643
644 void PSMarkSweep::mark_sweep_phase4() {
645 EventMark m("4 compact heap");
646 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer);
647
648 // All pointers are now adjusted, move objects accordingly
649
650 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
651 PSYoungGen* young_gen = heap->young_gen();
652 PSOldGen* old_gen = heap->old_gen();
653
654 old_gen->compact();
655 young_gen->compact();
656 }
657
658 jlong PSMarkSweep::millis_since_last_gc() {
659 // We need a monotonically non-decreasing time in ms but
660 // os::javaTimeMillis() does not guarantee monotonicity.
661 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
662 jlong ret_val = now - _time_of_last_gc;
663 // XXX See note in genCollectedHeap::millis_since_last_gc().
664 if (ret_val < 0) {
665 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
666 return 0;
667 }
668 return ret_val;
669 }
670
671 void PSMarkSweep::reset_millis_since_last_gc() {
672 // We need a monotonically non-decreasing time in ms but
673 // os::javaTimeMillis() does not guarantee monotonicity.
674 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
675 }