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/fprofiler.hpp"
54 #include "runtime/safepoint.hpp"
55 #include "runtime/vmThread.hpp"
56 #include "services/management.hpp"
57 #include "services/memoryService.hpp"
58 #include "utilities/align.hpp"
59 #include "utilities/events.hpp"
60 #include "utilities/stack.inline.hpp"
61
62 elapsedTimer PSMarkSweep::_accumulated_time;
63 jlong PSMarkSweep::_time_of_last_gc = 0;
64 CollectorCounters* PSMarkSweep::_counters = NULL;
65
66 void PSMarkSweep::initialize() {
67 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region();
68 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc
69 _counters = new CollectorCounters("PSMarkSweep", 1);
70 }
71
72 // This method contains all heap specific policy for invoking mark sweep.
73 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
74 // the heap. It will do nothing further. If we need to bail out for policy
75 // reasons, scavenge before full gc, or any other specialized behavior, it
76 // needs to be added here.
77 //
78 // Note that this method should only be called from the vm_thread while
79 // at a safepoint!
80 //
81 // Note that the all_soft_refs_clear flag in the collector policy
82 // may be true because this method can be called without intervening
83 // activity. For example when the heap space is tight and full measure
84 // are being taken to free space.
85
86 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
87 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
88 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
89 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
90
91 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
92 GCCause::Cause gc_cause = heap->gc_cause();
93 PSAdaptiveSizePolicy* policy = heap->size_policy();
94 IsGCActiveMark mark;
95
96 if (ScavengeBeforeFullGC) {
97 PSScavenge::invoke_no_policy();
98 }
99
100 const bool clear_all_soft_refs =
101 heap->collector_policy()->should_clear_all_soft_refs();
102
103 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
104 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
105 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
106 }
107
108 // This method contains no policy. You should probably
109 // be calling invoke() instead.
110 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
111 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
112 assert(ref_processor() != NULL, "Sanity");
113
114 if (GCLocker::check_active_before_gc()) {
115 return false;
116 }
117
118 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
119 GCCause::Cause gc_cause = heap->gc_cause();
120
121 GCIdMark gc_id_mark;
122 _gc_timer->register_gc_start();
123 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
124
125 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
126
127 // The scope of casr should end after code that can change
128 // CollectorPolicy::_should_clear_all_soft_refs.
129 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
130
131 PSYoungGen* young_gen = heap->young_gen();
132 PSOldGen* old_gen = heap->old_gen();
133
134 // Increment the invocation count
135 heap->increment_total_collections(true /* full */);
136
137 // Save information needed to minimize mangling
138 heap->record_gen_tops_before_GC();
139
140 // We need to track unique mark sweep invocations as well.
141 _total_invocations++;
142
143 heap->print_heap_before_gc();
144 heap->trace_heap_before_gc(_gc_tracer);
145
146 // Fill in TLABs
147 heap->accumulate_statistics_all_tlabs();
148 heap->ensure_parsability(true); // retire TLABs
149
150 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
151 HandleMark hm; // Discard invalid handles created during verification
152 Universe::verify("Before GC");
153 }
154
155 // Verify object start arrays
156 if (VerifyObjectStartArray &&
157 VerifyBeforeGC) {
158 old_gen->verify_object_start_array();
159 }
160
161 // Filled in below to track the state of the young gen after the collection.
162 bool eden_empty;
163 bool survivors_empty;
164 bool young_gen_empty;
165
166 {
167 HandleMark hm;
168
169 GCTraceCPUTime tcpu;
170 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true);
171
172 heap->pre_full_gc_dump(_gc_timer);
173
174 TraceCollectorStats tcs(counters());
175 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
176
177 if (TraceOldGenTime) accumulated_time()->start();
178
179 // Let the size policy know we're starting
180 size_policy->major_collection_begin();
181
182 CodeCache::gc_prologue();
183 BiasedLocking::preserve_marks();
184
185 // Capture metadata size before collection for sizing.
186 size_t metadata_prev_used = MetaspaceAux::used_bytes();
187
188 size_t old_gen_prev_used = old_gen->used_in_bytes();
189 size_t young_gen_prev_used = young_gen->used_in_bytes();
190
191 allocate_stacks();
192
193 #if defined(COMPILER2) || INCLUDE_JVMCI
194 DerivedPointerTable::clear();
195 #endif
196
197 ref_processor()->enable_discovery();
198 ref_processor()->setup_policy(clear_all_softrefs);
199
200 mark_sweep_phase1(clear_all_softrefs);
201
202 mark_sweep_phase2();
203
204 #if defined(COMPILER2) || INCLUDE_JVMCI
205 // Don't add any more derived pointers during phase3
206 assert(DerivedPointerTable::is_active(), "Sanity");
207 DerivedPointerTable::set_active(false);
208 #endif
209
210 mark_sweep_phase3();
211
212 mark_sweep_phase4();
213
214 restore_marks();
215
216 deallocate_stacks();
217
218 if (ZapUnusedHeapArea) {
219 // Do a complete mangle (top to end) because the usage for
220 // scratch does not maintain a top pointer.
221 young_gen->to_space()->mangle_unused_area_complete();
222 }
223
224 eden_empty = young_gen->eden_space()->is_empty();
225 if (!eden_empty) {
226 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
227 }
228
229 // Update heap occupancy information which is used as
230 // input to soft ref clearing policy at the next gc.
231 Universe::update_heap_info_at_gc();
232
233 survivors_empty = young_gen->from_space()->is_empty() &&
234 young_gen->to_space()->is_empty();
235 young_gen_empty = eden_empty && survivors_empty;
236
237 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
238 MemRegion old_mr = heap->old_gen()->reserved();
239 if (young_gen_empty) {
240 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
241 } else {
242 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
243 }
244
245 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
246 ClassLoaderDataGraph::purge();
247 MetaspaceAux::verify_metrics();
248
249 BiasedLocking::restore_marks();
250 CodeCache::gc_epilogue();
251 JvmtiExport::gc_epilogue();
252
253 #if defined(COMPILER2) || INCLUDE_JVMCI
254 DerivedPointerTable::update_pointers();
255 #endif
256
257 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_q());
258
259 ref_processor()->enqueue_discovered_references(NULL, &pt);
260
261 pt.print_enqueue_phase();
262
263 // Update time of last GC
264 reset_millis_since_last_gc();
265
266 // Let the size policy know we're done
267 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
268
269 if (UseAdaptiveSizePolicy) {
270
271 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
272 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
273 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
274
275 // Don't check if the size_policy is ready here. Let
276 // the size_policy check that internally.
277 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
278 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
279 // Swap the survivor spaces if from_space is empty. The
280 // resize_young_gen() called below is normally used after
281 // a successful young GC and swapping of survivor spaces;
282 // otherwise, it will fail to resize the young gen with
283 // the current implementation.
284 if (young_gen->from_space()->is_empty()) {
285 young_gen->from_space()->clear(SpaceDecorator::Mangle);
286 young_gen->swap_spaces();
287 }
288
289 // Calculate optimal free space amounts
290 assert(young_gen->max_size() >
291 young_gen->from_space()->capacity_in_bytes() +
292 young_gen->to_space()->capacity_in_bytes(),
293 "Sizes of space in young gen are out-of-bounds");
294
295 size_t young_live = young_gen->used_in_bytes();
296 size_t eden_live = young_gen->eden_space()->used_in_bytes();
297 size_t old_live = old_gen->used_in_bytes();
298 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
299 size_t max_old_gen_size = old_gen->max_gen_size();
300 size_t max_eden_size = young_gen->max_size() -
301 young_gen->from_space()->capacity_in_bytes() -
302 young_gen->to_space()->capacity_in_bytes();
303
304 // Used for diagnostics
305 size_policy->clear_generation_free_space_flags();
306
307 size_policy->compute_generations_free_space(young_live,
308 eden_live,
309 old_live,
310 cur_eden,
311 max_old_gen_size,
312 max_eden_size,
313 true /* full gc*/);
314
315 size_policy->check_gc_overhead_limit(young_live,
316 eden_live,
317 max_old_gen_size,
318 max_eden_size,
319 true /* full gc*/,
320 gc_cause,
321 heap->collector_policy());
322
323 size_policy->decay_supplemental_growth(true /* full gc*/);
324
325 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
326
327 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
328 size_policy->calculated_survivor_size_in_bytes());
329 }
330 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
331 }
332
333 if (UsePerfData) {
334 heap->gc_policy_counters()->update_counters();
335 heap->gc_policy_counters()->update_old_capacity(
336 old_gen->capacity_in_bytes());
337 heap->gc_policy_counters()->update_young_capacity(
338 young_gen->capacity_in_bytes());
339 }
340
341 heap->resize_all_tlabs();
342
343 // We collected the heap, recalculate the metaspace capacity
344 MetaspaceGC::compute_new_size();
345
346 if (TraceOldGenTime) accumulated_time()->stop();
347
348 young_gen->print_used_change(young_gen_prev_used);
349 old_gen->print_used_change(old_gen_prev_used);
350 MetaspaceAux::print_metaspace_change(metadata_prev_used);
351
352 // Track memory usage and detect low memory
353 MemoryService::track_memory_usage();
354 heap->update_counters();
355
356 heap->post_full_gc_dump(_gc_timer);
357 }
358
359 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
360 HandleMark hm; // Discard invalid handles created during verification
361 Universe::verify("After GC");
362 }
363
364 // Re-verify object start arrays
365 if (VerifyObjectStartArray &&
366 VerifyAfterGC) {
367 old_gen->verify_object_start_array();
368 }
369
370 if (ZapUnusedHeapArea) {
371 old_gen->object_space()->check_mangled_unused_area_complete();
372 }
373
374 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
375
376 heap->print_heap_after_gc();
377 heap->trace_heap_after_gc(_gc_tracer);
378
379 #ifdef TRACESPINNING
380 ParallelTaskTerminator::print_termination_counts();
381 #endif
382
383 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
384
385 _gc_timer->register_gc_end();
386
387 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
388
389 return true;
390 }
391
392 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
393 PSYoungGen* young_gen,
394 PSOldGen* old_gen) {
395 MutableSpace* const eden_space = young_gen->eden_space();
396 assert(!eden_space->is_empty(), "eden must be non-empty");
397 assert(young_gen->virtual_space()->alignment() ==
398 old_gen->virtual_space()->alignment(), "alignments do not match");
399
400 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
401 return false;
402 }
403
404 // Both generations must be completely committed.
405 if (young_gen->virtual_space()->uncommitted_size() != 0) {
406 return false;
407 }
408 if (old_gen->virtual_space()->uncommitted_size() != 0) {
409 return false;
410 }
411
412 // Figure out how much to take from eden. Include the average amount promoted
413 // in the total; otherwise the next young gen GC will simply bail out to a
414 // full GC.
415 const size_t alignment = old_gen->virtual_space()->alignment();
416 const size_t eden_used = eden_space->used_in_bytes();
417 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
418 const size_t absorb_size = align_up(eden_used + promoted, alignment);
419 const size_t eden_capacity = eden_space->capacity_in_bytes();
420
421 if (absorb_size >= eden_capacity) {
422 return false; // Must leave some space in eden.
423 }
424
425 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
426 if (new_young_size < young_gen->min_gen_size()) {
427 return false; // Respect young gen minimum size.
428 }
429
430 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: "
431 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
432 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
433 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
434 absorb_size / K,
435 eden_capacity / K, (eden_capacity - absorb_size) / K,
436 young_gen->from_space()->used_in_bytes() / K,
437 young_gen->to_space()->used_in_bytes() / K,
438 young_gen->capacity_in_bytes() / K, new_young_size / K);
439
440 // Fill the unused part of the old gen.
441 MutableSpace* const old_space = old_gen->object_space();
442 HeapWord* const unused_start = old_space->top();
443 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
444
445 if (unused_words > 0) {
446 if (unused_words < CollectedHeap::min_fill_size()) {
447 return false; // If the old gen cannot be filled, must give up.
448 }
449 CollectedHeap::fill_with_objects(unused_start, unused_words);
450 }
451
452 // Take the live data from eden and set both top and end in the old gen to
453 // eden top. (Need to set end because reset_after_change() mangles the region
454 // from end to virtual_space->high() in debug builds).
455 HeapWord* const new_top = eden_space->top();
456 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
457 absorb_size);
458 young_gen->reset_after_change();
459 old_space->set_top(new_top);
460 old_space->set_end(new_top);
461 old_gen->reset_after_change();
462
463 // Update the object start array for the filler object and the data from eden.
464 ObjectStartArray* const start_array = old_gen->start_array();
465 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
466 start_array->allocate_block(p);
467 }
468
469 // Could update the promoted average here, but it is not typically updated at
470 // full GCs and the value to use is unclear. Something like
471 //
472 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
473
474 size_policy->set_bytes_absorbed_from_eden(absorb_size);
475 return true;
476 }
477
478 void PSMarkSweep::allocate_stacks() {
479 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
480 PSYoungGen* young_gen = heap->young_gen();
481
482 MutableSpace* to_space = young_gen->to_space();
483 _preserved_marks = (PreservedMark*)to_space->top();
484 _preserved_count = 0;
485
486 // We want to calculate the size in bytes first.
487 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
488 // Now divide by the size of a PreservedMark
489 _preserved_count_max /= sizeof(PreservedMark);
490 }
491
492
493 void PSMarkSweep::deallocate_stacks() {
494 _preserved_mark_stack.clear(true);
495 _preserved_oop_stack.clear(true);
496 _marking_stack.clear();
497 _objarray_stack.clear(true);
498 }
499
500 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
501 // Recursively traverse all live objects and mark them
502 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer);
503
504 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
505
506 // Need to clear claim bits before the tracing starts.
507 ClassLoaderDataGraph::clear_claimed_marks();
508
509 // General strong roots.
510 {
511 ParallelScavengeHeap::ParStrongRootsScope psrs;
512 Universe::oops_do(mark_and_push_closure());
513 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
514 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
515 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
516 ObjectSynchronizer::oops_do(mark_and_push_closure());
517 FlatProfiler::oops_do(mark_and_push_closure());
518 Management::oops_do(mark_and_push_closure());
519 JvmtiExport::oops_do(mark_and_push_closure());
520 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
521 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
522 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
523 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
524 AOTLoader::oops_do(mark_and_push_closure());
525 }
526
527 // Flush marking stack.
528 follow_stack();
529
530 // Process reference objects found during marking
531 {
532 GCTraceTime(Debug, gc, phases) t("Reference Processing", _gc_timer);
533
534 ref_processor()->setup_policy(clear_all_softrefs);
535 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_q());
536 const ReferenceProcessorStats& stats =
537 ref_processor()->process_discovered_references(
538 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, &pt);
539 gc_tracer()->report_gc_reference_stats(stats);
540 pt.print_all_references();
541 }
542
543 // This is the point where the entire marking should have completed.
544 assert(_marking_stack.is_empty(), "Marking should have completed");
545
546 {
547 GCTraceTime(Debug, gc, phases) t("Class Unloading", _gc_timer);
548
549 // Unload classes and purge the SystemDictionary.
550 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), _gc_timer);
551
552 // Unload nmethods.
553 CodeCache::do_unloading(is_alive_closure(), purged_class);
554
555 // Prune dead klasses from subklass/sibling/implementor lists.
556 Klass::clean_weak_klass_links(is_alive_closure());
557 }
558
559 {
560 GCTraceTime(Debug, gc, phases) t("Scrub String Table", _gc_timer);
561 // Delete entries for dead interned strings.
562 StringTable::unlink(is_alive_closure());
563 }
564
565 {
566 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", _gc_timer);
567 // Clean up unreferenced symbols in symbol table.
568 SymbolTable::unlink();
569 }
570
571 _gc_tracer->report_object_count_after_gc(is_alive_closure());
572 }
573
574
575 void PSMarkSweep::mark_sweep_phase2() {
576 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer);
577
578 // Now all live objects are marked, compute the new object addresses.
579
580 // It is not required that we traverse spaces in the same order in
581 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
582 // tracking expects us to do so. See comment under phase4.
583
584 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
585 PSOldGen* old_gen = heap->old_gen();
586
587 // Begin compacting into the old gen
588 PSMarkSweepDecorator::set_destination_decorator_tenured();
589
590 // This will also compact the young gen spaces.
591 old_gen->precompact();
592 }
593
594 void PSMarkSweep::mark_sweep_phase3() {
595 // Adjust the pointers to reflect the new locations
596 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", _gc_timer);
597
598 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
599 PSYoungGen* young_gen = heap->young_gen();
600 PSOldGen* old_gen = heap->old_gen();
601
602 // Need to clear claim bits before the tracing starts.
603 ClassLoaderDataGraph::clear_claimed_marks();
604
605 // General strong roots.
606 Universe::oops_do(adjust_pointer_closure());
607 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
608 Threads::oops_do(adjust_pointer_closure(), NULL);
609 ObjectSynchronizer::oops_do(adjust_pointer_closure());
610 FlatProfiler::oops_do(adjust_pointer_closure());
611 Management::oops_do(adjust_pointer_closure());
612 JvmtiExport::oops_do(adjust_pointer_closure());
613 SystemDictionary::oops_do(adjust_pointer_closure());
614 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
615
616 // Now adjust pointers in remaining weak roots. (All of which should
617 // have been cleared if they pointed to non-surviving objects.)
618 // Global (weak) JNI handles
619 JNIHandles::weak_oops_do(adjust_pointer_closure());
620
621 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
622 CodeCache::blobs_do(&adjust_from_blobs);
623 AOTLoader::oops_do(adjust_pointer_closure());
624 StringTable::oops_do(adjust_pointer_closure());
625 ref_processor()->weak_oops_do(adjust_pointer_closure());
626 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
627
628 adjust_marks();
629
630 young_gen->adjust_pointers();
631 old_gen->adjust_pointers();
632 }
633
634 void PSMarkSweep::mark_sweep_phase4() {
635 EventMark m("4 compact heap");
636 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer);
637
638 // All pointers are now adjusted, move objects accordingly
639
640 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
641 PSYoungGen* young_gen = heap->young_gen();
642 PSOldGen* old_gen = heap->old_gen();
643
644 old_gen->compact();
645 young_gen->compact();
646 }
647
648 jlong PSMarkSweep::millis_since_last_gc() {
649 // We need a monotonically non-decreasing time in ms but
650 // os::javaTimeMillis() does not guarantee monotonicity.
651 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
652 jlong ret_val = now - _time_of_last_gc;
653 // XXX See note in genCollectedHeap::millis_since_last_gc().
654 if (ret_val < 0) {
655 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
656 return 0;
657 }
658 return ret_val;
659 }
660
661 void PSMarkSweep::reset_millis_since_last_gc() {
662 // We need a monotonically non-decreasing time in ms but
663 // os::javaTimeMillis() does not guarantee monotonicity.
664 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
665 }