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 (TraceOldGenTime) accumulated_time()->start();
177
178 // Let the size policy know we're starting
179 size_policy->major_collection_begin();
180
181 CodeCache::gc_prologue();
182 BiasedLocking::preserve_marks();
183
184 // Capture metadata size before collection for sizing.
185 size_t metadata_prev_used = MetaspaceAux::used_bytes();
186
187 size_t old_gen_prev_used = old_gen->used_in_bytes();
188 size_t young_gen_prev_used = young_gen->used_in_bytes();
189
190 allocate_stacks();
191
192 #if defined(COMPILER2) || INCLUDE_JVMCI
193 DerivedPointerTable::clear();
194 #endif
195
196 ref_processor()->enable_discovery();
197 ref_processor()->setup_policy(clear_all_softrefs);
198
199 mark_sweep_phase1(clear_all_softrefs);
200
201 mark_sweep_phase2();
202
203 #if defined(COMPILER2) || INCLUDE_JVMCI
204 // Don't add any more derived pointers during phase3
205 assert(DerivedPointerTable::is_active(), "Sanity");
206 DerivedPointerTable::set_active(false);
207 #endif
208
209 mark_sweep_phase3();
210
211 mark_sweep_phase4();
212
213 restore_marks();
214
215 deallocate_stacks();
216
217 if (ZapUnusedHeapArea) {
218 // Do a complete mangle (top to end) because the usage for
219 // scratch does not maintain a top pointer.
220 young_gen->to_space()->mangle_unused_area_complete();
221 }
222
223 eden_empty = young_gen->eden_space()->is_empty();
224 if (!eden_empty) {
225 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
226 }
227
228 // Update heap occupancy information which is used as
229 // input to soft ref clearing policy at the next gc.
230 Universe::update_heap_info_at_gc();
231
232 survivors_empty = young_gen->from_space()->is_empty() &&
233 young_gen->to_space()->is_empty();
234 young_gen_empty = eden_empty && survivors_empty;
235
236 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
237 MemRegion old_mr = heap->old_gen()->reserved();
238 if (young_gen_empty) {
239 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
240 } else {
241 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
242 }
243
244 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
245 ClassLoaderDataGraph::purge();
246 MetaspaceAux::verify_metrics();
247
248 BiasedLocking::restore_marks();
249 CodeCache::gc_epilogue();
250 JvmtiExport::gc_epilogue();
251
252 #if defined(COMPILER2) || INCLUDE_JVMCI
253 DerivedPointerTable::update_pointers();
254 #endif
255
256 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_q());
257
258 ref_processor()->enqueue_discovered_references(NULL, &pt);
259
260 pt.print_enqueue_phase();
261
262 // Update time of last GC
263 reset_millis_since_last_gc();
264
265 // Let the size policy know we're done
266 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
267
268 if (UseAdaptiveSizePolicy) {
269
270 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
271 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
272 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
273
274 // Don't check if the size_policy is ready here. Let
275 // the size_policy check that internally.
276 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
277 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
278 // Swap the survivor spaces if from_space is empty. The
279 // resize_young_gen() called below is normally used after
280 // a successful young GC and swapping of survivor spaces;
281 // otherwise, it will fail to resize the young gen with
282 // the current implementation.
283 if (young_gen->from_space()->is_empty()) {
284 young_gen->from_space()->clear(SpaceDecorator::Mangle);
285 young_gen->swap_spaces();
286 }
287
288 // Calculate optimal free space amounts
289 assert(young_gen->max_size() >
290 young_gen->from_space()->capacity_in_bytes() +
291 young_gen->to_space()->capacity_in_bytes(),
292 "Sizes of space in young gen are out-of-bounds");
293
294 size_t young_live = young_gen->used_in_bytes();
295 size_t eden_live = young_gen->eden_space()->used_in_bytes();
296 size_t old_live = old_gen->used_in_bytes();
297 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
298 size_t max_old_gen_size = old_gen->max_gen_size();
299 size_t max_eden_size = young_gen->max_size() -
300 young_gen->from_space()->capacity_in_bytes() -
301 young_gen->to_space()->capacity_in_bytes();
302
303 // Used for diagnostics
304 size_policy->clear_generation_free_space_flags();
305
306 size_policy->compute_generations_free_space(young_live,
307 eden_live,
308 old_live,
309 cur_eden,
310 max_old_gen_size,
311 max_eden_size,
312 true /* full gc*/);
313
314 size_policy->check_gc_overhead_limit(young_live,
315 eden_live,
316 max_old_gen_size,
317 max_eden_size,
318 true /* full gc*/,
319 gc_cause,
320 heap->collector_policy());
321
322 size_policy->decay_supplemental_growth(true /* full gc*/);
323
324 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
325
326 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
327 size_policy->calculated_survivor_size_in_bytes());
328 }
329 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
330 }
331
332 if (UsePerfData) {
333 heap->gc_policy_counters()->update_counters();
334 heap->gc_policy_counters()->update_old_capacity(
335 old_gen->capacity_in_bytes());
336 heap->gc_policy_counters()->update_young_capacity(
337 young_gen->capacity_in_bytes());
338 }
339
340 heap->resize_all_tlabs();
341
342 // We collected the heap, recalculate the metaspace capacity
343 MetaspaceGC::compute_new_size();
344
345 if (TraceOldGenTime) accumulated_time()->stop();
346
347 young_gen->print_used_change(young_gen_prev_used);
348 old_gen->print_used_change(old_gen_prev_used);
349 MetaspaceAux::print_metaspace_change(metadata_prev_used);
350
351 // Track memory usage and detect low memory
352 MemoryService::track_memory_usage();
353 heap->update_counters();
354
355 heap->post_full_gc_dump(_gc_timer);
356 }
357
358 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
359 HandleMark hm; // Discard invalid handles created during verification
360 Universe::verify("After GC");
361 }
362
363 // Re-verify object start arrays
364 if (VerifyObjectStartArray &&
365 VerifyAfterGC) {
366 old_gen->verify_object_start_array();
367 }
368
369 if (ZapUnusedHeapArea) {
370 old_gen->object_space()->check_mangled_unused_area_complete();
371 }
372
373 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
374
375 heap->print_heap_after_gc();
376 heap->trace_heap_after_gc(_gc_tracer);
377
378 #ifdef TRACESPINNING
379 ParallelTaskTerminator::print_termination_counts();
380 #endif
381
382 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
383
384 _gc_timer->register_gc_end();
385
386 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
387
388 return true;
389 }
390
391 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
392 PSYoungGen* young_gen,
393 PSOldGen* old_gen) {
394 MutableSpace* const eden_space = young_gen->eden_space();
395 assert(!eden_space->is_empty(), "eden must be non-empty");
396 assert(young_gen->virtual_space()->alignment() ==
397 old_gen->virtual_space()->alignment(), "alignments do not match");
398
399 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
400 return false;
401 }
402
403 // Both generations must be completely committed.
404 if (young_gen->virtual_space()->uncommitted_size() != 0) {
405 return false;
406 }
407 if (old_gen->virtual_space()->uncommitted_size() != 0) {
408 return false;
409 }
410
411 // Figure out how much to take from eden. Include the average amount promoted
412 // in the total; otherwise the next young gen GC will simply bail out to a
413 // full GC.
414 const size_t alignment = old_gen->virtual_space()->alignment();
415 const size_t eden_used = eden_space->used_in_bytes();
416 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
417 const size_t absorb_size = align_up(eden_used + promoted, alignment);
418 const size_t eden_capacity = eden_space->capacity_in_bytes();
419
420 if (absorb_size >= eden_capacity) {
421 return false; // Must leave some space in eden.
422 }
423
424 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
425 if (new_young_size < young_gen->min_gen_size()) {
426 return false; // Respect young gen minimum size.
427 }
428
429 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: "
430 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
431 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
432 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
433 absorb_size / K,
434 eden_capacity / K, (eden_capacity - absorb_size) / K,
435 young_gen->from_space()->used_in_bytes() / K,
436 young_gen->to_space()->used_in_bytes() / K,
437 young_gen->capacity_in_bytes() / K, new_young_size / K);
438
439 // Fill the unused part of the old gen.
440 MutableSpace* const old_space = old_gen->object_space();
441 HeapWord* const unused_start = old_space->top();
442 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
443
444 if (unused_words > 0) {
445 if (unused_words < CollectedHeap::min_fill_size()) {
446 return false; // If the old gen cannot be filled, must give up.
447 }
448 CollectedHeap::fill_with_objects(unused_start, unused_words);
449 }
450
451 // Take the live data from eden and set both top and end in the old gen to
452 // eden top. (Need to set end because reset_after_change() mangles the region
453 // from end to virtual_space->high() in debug builds).
454 HeapWord* const new_top = eden_space->top();
455 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
456 absorb_size);
457 young_gen->reset_after_change();
458 old_space->set_top(new_top);
459 old_space->set_end(new_top);
460 old_gen->reset_after_change();
461
462 // Update the object start array for the filler object and the data from eden.
463 ObjectStartArray* const start_array = old_gen->start_array();
464 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
465 start_array->allocate_block(p);
466 }
467
468 // Could update the promoted average here, but it is not typically updated at
469 // full GCs and the value to use is unclear. Something like
470 //
471 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
472
473 size_policy->set_bytes_absorbed_from_eden(absorb_size);
474 return true;
475 }
476
477 void PSMarkSweep::allocate_stacks() {
478 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
479 PSYoungGen* young_gen = heap->young_gen();
480
481 MutableSpace* to_space = young_gen->to_space();
482 _preserved_marks = (PreservedMark*)to_space->top();
483 _preserved_count = 0;
484
485 // We want to calculate the size in bytes first.
486 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
487 // Now divide by the size of a PreservedMark
488 _preserved_count_max /= sizeof(PreservedMark);
489 }
490
491
492 void PSMarkSweep::deallocate_stacks() {
493 _preserved_mark_stack.clear(true);
494 _preserved_oop_stack.clear(true);
495 _marking_stack.clear();
496 _objarray_stack.clear(true);
497 }
498
499 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
500 // Recursively traverse all live objects and mark them
501 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer);
502
503 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
504
505 // Need to clear claim bits before the tracing starts.
506 ClassLoaderDataGraph::clear_claimed_marks();
507
508 // General strong roots.
509 {
510 ParallelScavengeHeap::ParStrongRootsScope psrs;
511 Universe::oops_do(mark_and_push_closure());
512 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
513 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
514 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
515 ObjectSynchronizer::oops_do(mark_and_push_closure());
516 Management::oops_do(mark_and_push_closure());
517 JvmtiExport::oops_do(mark_and_push_closure());
518 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
519 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
520 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
521 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
522 AOTLoader::oops_do(mark_and_push_closure());
523 }
524
525 // Flush marking stack.
526 follow_stack();
527
528 // Process reference objects found during marking
529 {
530 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer);
531
532 ref_processor()->setup_policy(clear_all_softrefs);
533 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_q());
534 const ReferenceProcessorStats& stats =
535 ref_processor()->process_discovered_references(
536 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, &pt);
537 gc_tracer()->report_gc_reference_stats(stats);
538 pt.print_all_references();
539 }
540
541 // This is the point where the entire marking should have completed.
542 assert(_marking_stack.is_empty(), "Marking should have completed");
543
544 {
545 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer);
546
547 // Unload classes and purge the SystemDictionary.
548 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), _gc_timer);
549
550 // Unload nmethods.
551 CodeCache::do_unloading(is_alive_closure(), purged_class);
552
553 // Prune dead klasses from subklass/sibling/implementor lists.
554 Klass::clean_weak_klass_links(is_alive_closure());
555 }
556
557 {
558 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer);
559 // Delete entries for dead interned strings.
560 StringTable::unlink(is_alive_closure());
561 }
562
563 {
564 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer);
565 // Clean up unreferenced symbols in symbol table.
566 SymbolTable::unlink();
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 JNIHandles::weak_oops_do(adjust_pointer_closure());
617
618 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
619 CodeCache::blobs_do(&adjust_from_blobs);
620 AOTLoader::oops_do(adjust_pointer_closure());
621 StringTable::oops_do(adjust_pointer_closure());
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 }