1 /*
2 * Copyright (c) 2001, 2017, 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/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "code/codeCache.hpp"
31 #include "gc/parallel/parallelScavengeHeap.hpp"
32 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
33 #include "gc/parallel/psMarkSweep.hpp"
34 #include "gc/parallel/psMarkSweepDecorator.hpp"
35 #include "gc/parallel/psOldGen.hpp"
36 #include "gc/parallel/psScavenge.hpp"
37 #include "gc/parallel/psYoungGen.hpp"
38 #include "gc/serial/markSweep.hpp"
39 #include "gc/shared/gcCause.hpp"
40 #include "gc/shared/gcHeapSummary.hpp"
41 #include "gc/shared/gcId.hpp"
42 #include "gc/shared/gcLocker.inline.hpp"
43 #include "gc/shared/gcTimer.hpp"
44 #include "gc/shared/gcTrace.hpp"
45 #include "gc/shared/gcTraceTime.inline.hpp"
46 #include "gc/shared/isGCActiveMark.hpp"
47 #include "gc/shared/referencePolicy.hpp"
48 #include "gc/shared/referenceProcessor.hpp"
49 #include "gc/shared/spaceDecorator.hpp"
50 #include "logging/log.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "runtime/biasedLocking.hpp"
53 #include "runtime/safepoint.hpp"
54 #include "runtime/vmThread.hpp"
55 #include "services/management.hpp"
56 #include "services/memoryService.hpp"
57 #include "utilities/align.hpp"
58 #include "utilities/events.hpp"
59 #include "utilities/stack.inline.hpp"
60
61 elapsedTimer PSMarkSweep::_accumulated_time;
62 jlong PSMarkSweep::_time_of_last_gc = 0;
63 CollectorCounters* PSMarkSweep::_counters = NULL;
64
65 void PSMarkSweep::initialize() {
66 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region();
67 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc
68 _counters = new CollectorCounters("PSMarkSweep", 1);
69 }
70
71 // This method contains all heap specific policy for invoking mark sweep.
72 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
73 // the heap. It will do nothing further. If we need to bail out for policy
74 // reasons, scavenge before full gc, or any other specialized behavior, it
75 // needs to be added here.
76 //
77 // Note that this method should only be called from the vm_thread while
78 // at a safepoint!
79 //
80 // Note that the all_soft_refs_clear flag in the collector policy
81 // may be true because this method can be called without intervening
82 // activity. For example when the heap space is tight and full measure
83 // are being taken to free space.
84
85 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
86 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
87 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
88 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
89
90 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
91 GCCause::Cause gc_cause = heap->gc_cause();
92 PSAdaptiveSizePolicy* policy = heap->size_policy();
93 IsGCActiveMark mark;
94
95 if (ScavengeBeforeFullGC) {
96 PSScavenge::invoke_no_policy();
97 }
98
99 const bool clear_all_soft_refs =
100 heap->collector_policy()->should_clear_all_soft_refs();
101
102 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
103 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
104 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
105 }
106
107 // This method contains no policy. You should probably
108 // be calling invoke() instead.
109 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
110 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
111 assert(ref_processor() != NULL, "Sanity");
112
113 if (GCLocker::check_active_before_gc()) {
114 return false;
115 }
116
117 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
118 GCCause::Cause gc_cause = heap->gc_cause();
119
120 GCIdMark gc_id_mark;
121 _gc_timer->register_gc_start();
122 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
123
124 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
125
126 // The scope of casr should end after code that can change
127 // CollectorPolicy::_should_clear_all_soft_refs.
128 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
129
130 PSYoungGen* young_gen = heap->young_gen();
131 PSOldGen* old_gen = heap->old_gen();
132
133 // Increment the invocation count
134 heap->increment_total_collections(true /* full */);
135
136 // Save information needed to minimize mangling
137 heap->record_gen_tops_before_GC();
138
139 // We need to track unique mark sweep invocations as well.
140 _total_invocations++;
141
142 heap->print_heap_before_gc();
143 heap->trace_heap_before_gc(_gc_tracer);
144
145 // Fill in TLABs
146 heap->accumulate_statistics_all_tlabs();
147 heap->ensure_parsability(true); // retire TLABs
148
149 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
150 HandleMark hm; // Discard invalid handles created during verification
151 Universe::verify("Before GC");
152 }
153
154 // Verify object start arrays
155 if (VerifyObjectStartArray &&
156 VerifyBeforeGC) {
157 old_gen->verify_object_start_array();
158 }
159
160 // Filled in below to track the state of the young gen after the collection.
161 bool eden_empty;
162 bool survivors_empty;
163 bool young_gen_empty;
164
165 {
166 HandleMark hm;
167
168 GCTraceCPUTime tcpu;
169 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true);
170
171 heap->pre_full_gc_dump(_gc_timer);
172
173 TraceCollectorStats tcs(counters());
174 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
175
176 if (log_is_enabled(Debug, gc, heap, exit)) {
177 accumulated_time()->start();
178 }
179
180 // Let the size policy know we're starting
181 size_policy->major_collection_begin();
182
183 CodeCache::gc_prologue();
184 BiasedLocking::preserve_marks();
185
186 // Capture metadata size before collection for sizing.
187 size_t metadata_prev_used = MetaspaceAux::used_bytes();
188
189 size_t old_gen_prev_used = old_gen->used_in_bytes();
190 size_t young_gen_prev_used = young_gen->used_in_bytes();
191
192 allocate_stacks();
193
194 #if defined(COMPILER2) || INCLUDE_JVMCI
195 DerivedPointerTable::clear();
196 #endif
197
198 ref_processor()->enable_discovery();
199 ref_processor()->setup_policy(clear_all_softrefs);
200
201 mark_sweep_phase1(clear_all_softrefs);
202
203 mark_sweep_phase2();
204
205 #if defined(COMPILER2) || INCLUDE_JVMCI
206 // Don't add any more derived pointers during phase3
207 assert(DerivedPointerTable::is_active(), "Sanity");
208 DerivedPointerTable::set_active(false);
209 #endif
210
211 mark_sweep_phase3();
212
213 mark_sweep_phase4();
214
215 restore_marks();
216
217 deallocate_stacks();
218
219 if (ZapUnusedHeapArea) {
220 // Do a complete mangle (top to end) because the usage for
221 // scratch does not maintain a top pointer.
222 young_gen->to_space()->mangle_unused_area_complete();
223 }
224
225 eden_empty = young_gen->eden_space()->is_empty();
226 if (!eden_empty) {
227 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
228 }
229
230 // Update heap occupancy information which is used as
231 // input to soft ref clearing policy at the next gc.
232 Universe::update_heap_info_at_gc();
233
234 survivors_empty = young_gen->from_space()->is_empty() &&
235 young_gen->to_space()->is_empty();
236 young_gen_empty = eden_empty && survivors_empty;
237
238 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
239 MemRegion old_mr = heap->old_gen()->reserved();
240 if (young_gen_empty) {
241 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
242 } else {
243 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
244 }
245
246 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
247 ClassLoaderDataGraph::purge();
248 MetaspaceAux::verify_metrics();
249
250 BiasedLocking::restore_marks();
251 CodeCache::gc_epilogue();
252 JvmtiExport::gc_epilogue();
253
254 #if defined(COMPILER2) || INCLUDE_JVMCI
255 DerivedPointerTable::update_pointers();
256 #endif
257
258 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_q());
259
260 ref_processor()->enqueue_discovered_references(NULL, &pt);
261
262 pt.print_enqueue_phase();
263
264 // Update time of last GC
265 reset_millis_since_last_gc();
266
267 // Let the size policy know we're done
268 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
269
270 if (UseAdaptiveSizePolicy) {
271
272 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
273 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
274 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
275
276 // Don't check if the size_policy is ready here. Let
277 // the size_policy check that internally.
278 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
279 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
280 // Swap the survivor spaces if from_space is empty. The
281 // resize_young_gen() called below is normally used after
282 // a successful young GC and swapping of survivor spaces;
283 // otherwise, it will fail to resize the young gen with
284 // the current implementation.
285 if (young_gen->from_space()->is_empty()) {
286 young_gen->from_space()->clear(SpaceDecorator::Mangle);
287 young_gen->swap_spaces();
288 }
289
290 // Calculate optimal free space amounts
291 assert(young_gen->max_size() >
292 young_gen->from_space()->capacity_in_bytes() +
293 young_gen->to_space()->capacity_in_bytes(),
294 "Sizes of space in young gen are out-of-bounds");
295
296 size_t young_live = young_gen->used_in_bytes();
297 size_t eden_live = young_gen->eden_space()->used_in_bytes();
298 size_t old_live = old_gen->used_in_bytes();
299 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
300 size_t max_old_gen_size = old_gen->max_gen_size();
301 size_t max_eden_size = young_gen->max_size() -
302 young_gen->from_space()->capacity_in_bytes() -
303 young_gen->to_space()->capacity_in_bytes();
304
305 // Used for diagnostics
306 size_policy->clear_generation_free_space_flags();
307
308 size_policy->compute_generations_free_space(young_live,
309 eden_live,
310 old_live,
311 cur_eden,
312 max_old_gen_size,
313 max_eden_size,
314 true /* full gc*/);
315
316 size_policy->check_gc_overhead_limit(young_live,
317 eden_live,
318 max_old_gen_size,
319 max_eden_size,
320 true /* full gc*/,
321 gc_cause,
322 heap->collector_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(young_gen_prev_used);
352 old_gen->print_used_change(old_gen_prev_used);
353 MetaspaceAux::print_metaspace_change(metadata_prev_used);
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(heap, ergo)(" 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::always_strong_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 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
526 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()->num_q());
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("Class Unloading", _gc_timer);
550
551 // Unload classes and purge the SystemDictionary.
552 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), _gc_timer);
553
554 // Unload nmethods.
555 CodeCache::do_unloading(is_alive_closure(), purged_class);
556
557 // Prune dead klasses from subklass/sibling/implementor lists.
558 Klass::clean_weak_klass_links(is_alive_closure());
559 }
560
561 {
562 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer);
563 // Delete entries for dead interned strings.
564 StringTable::unlink(is_alive_closure());
565 }
566
567 {
568 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer);
569 // Clean up unreferenced symbols in symbol table.
570 SymbolTable::unlink();
571 }
572
573 _gc_tracer->report_object_count_after_gc(is_alive_closure());
574 }
575
576
577 void PSMarkSweep::mark_sweep_phase2() {
578 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer);
579
580 // Now all live objects are marked, compute the new object addresses.
581
582 // It is not required that we traverse spaces in the same order in
583 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
584 // tracking expects us to do so. See comment under phase4.
585
586 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
587 PSOldGen* old_gen = heap->old_gen();
588
589 // Begin compacting into the old gen
590 PSMarkSweepDecorator::set_destination_decorator_tenured();
591
592 // This will also compact the young gen spaces.
593 old_gen->precompact();
594 }
595
596 void PSMarkSweep::mark_sweep_phase3() {
597 // Adjust the pointers to reflect the new locations
598 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer);
599
600 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
601 PSYoungGen* young_gen = heap->young_gen();
602 PSOldGen* old_gen = heap->old_gen();
603
604 // Need to clear claim bits before the tracing starts.
605 ClassLoaderDataGraph::clear_claimed_marks();
606
607 // General strong roots.
608 Universe::oops_do(adjust_pointer_closure());
609 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
610 Threads::oops_do(adjust_pointer_closure(), NULL);
611 ObjectSynchronizer::oops_do(adjust_pointer_closure());
612 Management::oops_do(adjust_pointer_closure());
613 JvmtiExport::oops_do(adjust_pointer_closure());
614 SystemDictionary::oops_do(adjust_pointer_closure());
615 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
616
617 // Now adjust pointers in remaining weak roots. (All of which should
618 // have been cleared if they pointed to non-surviving objects.)
619 // Global (weak) JNI handles
620 JNIHandles::weak_oops_do(adjust_pointer_closure());
621
622 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
623 CodeCache::blobs_do(&adjust_from_blobs);
624 AOTLoader::oops_do(adjust_pointer_closure());
625 StringTable::oops_do(adjust_pointer_closure());
626 ref_processor()->weak_oops_do(adjust_pointer_closure());
627 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
628
629 adjust_marks();
630
631 young_gen->adjust_pointers();
632 old_gen->adjust_pointers();
633 }
634
635 void PSMarkSweep::mark_sweep_phase4() {
636 EventMark m("4 compact heap");
637 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer);
638
639 // All pointers are now adjusted, move objects accordingly
640
641 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
642 PSYoungGen* young_gen = heap->young_gen();
643 PSOldGen* old_gen = heap->old_gen();
644
645 old_gen->compact();
646 young_gen->compact();
647 }
648
649 jlong PSMarkSweep::millis_since_last_gc() {
650 // We need a monotonically non-decreasing time in ms but
651 // os::javaTimeMillis() does not guarantee monotonicity.
652 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
653 jlong ret_val = now - _time_of_last_gc;
654 // XXX See note in genCollectedHeap::millis_since_last_gc().
655 if (ret_val < 0) {
656 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
657 return 0;
658 }
659 return ret_val;
660 }
661
662 void PSMarkSweep::reset_millis_since_last_gc() {
663 // We need a monotonically non-decreasing time in ms but
664 // os::javaTimeMillis() does not guarantee monotonicity.
665 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
666 }