1 /*
2 * Copyright (c) 2001, 2015, 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 "classfile/stringTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc/parallel/parallelScavengeHeap.hpp"
30 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
31 #include "gc/parallel/psMarkSweep.hpp"
32 #include "gc/parallel/psMarkSweepDecorator.hpp"
33 #include "gc/parallel/psOldGen.hpp"
34 #include "gc/parallel/psScavenge.hpp"
35 #include "gc/parallel/psYoungGen.hpp"
36 #include "gc/serial/markSweep.hpp"
37 #include "gc/shared/gcCause.hpp"
38 #include "gc/shared/gcHeapSummary.hpp"
39 #include "gc/shared/gcLocker.inline.hpp"
40 #include "gc/shared/gcTimer.hpp"
41 #include "gc/shared/gcTrace.hpp"
42 #include "gc/shared/gcTraceTime.hpp"
43 #include "gc/shared/isGCActiveMark.hpp"
44 #include "gc/shared/referencePolicy.hpp"
45 #include "gc/shared/referenceProcessor.hpp"
46 #include "gc/shared/spaceDecorator.hpp"
47 #include "oops/oop.inline.hpp"
48 #include "runtime/biasedLocking.hpp"
49 #include "runtime/fprofiler.hpp"
50 #include "runtime/safepoint.hpp"
51 #include "runtime/vmThread.hpp"
52 #include "services/management.hpp"
53 #include "services/memoryService.hpp"
54 #include "utilities/events.hpp"
55 #include "utilities/stack.inline.hpp"
56
57 elapsedTimer PSMarkSweep::_accumulated_time;
58 jlong PSMarkSweep::_time_of_last_gc = 0;
59 CollectorCounters* PSMarkSweep::_counters = NULL;
60
61 void PSMarkSweep::initialize() {
62 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region();
63 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc
64 _counters = new CollectorCounters("PSMarkSweep", 1);
65 }
66
67 // This method contains all heap specific policy for invoking mark sweep.
68 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
69 // the heap. It will do nothing further. If we need to bail out for policy
70 // reasons, scavenge before full gc, or any other specialized behavior, it
71 // needs to be added here.
72 //
73 // Note that this method should only be called from the vm_thread while
74 // at a safepoint!
75 //
76 // Note that the all_soft_refs_clear flag in the collector policy
77 // may be true because this method can be called without intervening
78 // activity. For example when the heap space is tight and full measure
79 // are being taken to free space.
80
81 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
82 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
83 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
84 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
85
86 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
87 GCCause::Cause gc_cause = heap->gc_cause();
88 PSAdaptiveSizePolicy* policy = heap->size_policy();
89 IsGCActiveMark mark;
90
91 if (ScavengeBeforeFullGC) {
92 PSScavenge::invoke_no_policy();
93 }
94
95 const bool clear_all_soft_refs =
96 heap->collector_policy()->should_clear_all_soft_refs();
97
98 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
99 UIntXFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
100 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
101 }
102
103 // This method contains no policy. You should probably
104 // be calling invoke() instead.
105 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
106 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
107 assert(ref_processor() != NULL, "Sanity");
108
109 if (GC_locker::check_active_before_gc()) {
110 return false;
111 }
112
113 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
114 GCCause::Cause gc_cause = heap->gc_cause();
115
116 _gc_timer->register_gc_start();
117 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
118
119 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
120
121 // The scope of casr should end after code that can change
122 // CollectorPolicy::_should_clear_all_soft_refs.
123 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
124
125 PSYoungGen* young_gen = heap->young_gen();
126 PSOldGen* old_gen = heap->old_gen();
127
128 // Increment the invocation count
129 heap->increment_total_collections(true /* full */);
130
131 // Save information needed to minimize mangling
132 heap->record_gen_tops_before_GC();
133
134 // We need to track unique mark sweep invocations as well.
135 _total_invocations++;
136
137 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
138
139 heap->print_heap_before_gc();
140 heap->trace_heap_before_gc(_gc_tracer);
141
142 // Fill in TLABs
143 heap->accumulate_statistics_all_tlabs();
144 heap->ensure_parsability(true); // retire TLABs
145
146 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
147 HandleMark hm; // Discard invalid handles created during verification
148 Universe::verify(" VerifyBeforeGC:");
149 }
150
151 // Verify object start arrays
152 if (VerifyObjectStartArray &&
153 VerifyBeforeGC) {
154 old_gen->verify_object_start_array();
155 }
156
157 heap->pre_full_gc_dump(_gc_timer);
158
159 // Filled in below to track the state of the young gen after the collection.
160 bool eden_empty;
161 bool survivors_empty;
162 bool young_gen_empty;
163
164 {
165 HandleMark hm;
166
167 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
168 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer->gc_id());
169 TraceCollectorStats tcs(counters());
170 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
171
172 if (TraceOldGenTime) accumulated_time()->start();
173
174 // Let the size policy know we're starting
175 size_policy->major_collection_begin();
176
177 CodeCache::gc_prologue();
178 BiasedLocking::preserve_marks();
179
180 // Capture heap size before collection for printing.
181 size_t prev_used = heap->used();
182
183 // Capture metadata size before collection for sizing.
184 size_t metadata_prev_used = MetaspaceAux::used_bytes();
185
186 // For PrintGCDetails
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 ref_processor()->enqueue_discovered_references(NULL);
257
258 // Update time of last GC
259 reset_millis_since_last_gc();
260
261 // Let the size policy know we're done
262 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
263
264 if (UseAdaptiveSizePolicy) {
265
266 if (PrintAdaptiveSizePolicy) {
267 gclog_or_tty->print("AdaptiveSizeStart: ");
268 gclog_or_tty->stamp();
269 gclog_or_tty->print_cr(" collection: %d ",
270 heap->total_collections());
271 if (Verbose) {
272 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
273 " young_gen_capacity: " SIZE_FORMAT,
274 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
275 }
276 }
277
278 // Don't check if the size_policy is ready here. Let
279 // the size_policy check that internally.
280 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
281 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
282 // Swap the survivor spaces if from_space is empty. The
283 // resize_young_gen() called below is normally used after
284 // a successful young GC and swapping of survivor spaces;
285 // otherwise, it will fail to resize the young gen with
286 // the current implementation.
287 if (young_gen->from_space()->is_empty()) {
288 young_gen->from_space()->clear(SpaceDecorator::Mangle);
289 young_gen->swap_spaces();
290 }
291
292 // Calculate optimal free space amounts
293 assert(young_gen->max_size() >
294 young_gen->from_space()->capacity_in_bytes() +
295 young_gen->to_space()->capacity_in_bytes(),
296 "Sizes of space in young gen are out-of-bounds");
297
298 size_t young_live = young_gen->used_in_bytes();
299 size_t eden_live = young_gen->eden_space()->used_in_bytes();
300 size_t old_live = old_gen->used_in_bytes();
301 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
302 size_t max_old_gen_size = old_gen->max_gen_size();
303 size_t max_eden_size = young_gen->max_size() -
304 young_gen->from_space()->capacity_in_bytes() -
305 young_gen->to_space()->capacity_in_bytes();
306
307 // Used for diagnostics
308 size_policy->clear_generation_free_space_flags();
309
310 size_policy->compute_generations_free_space(young_live,
311 eden_live,
312 old_live,
313 cur_eden,
314 max_old_gen_size,
315 max_eden_size,
316 true /* full gc*/);
317
318 size_policy->check_gc_overhead_limit(young_live,
319 eden_live,
320 max_old_gen_size,
321 max_eden_size,
322 true /* full gc*/,
323 gc_cause,
324 heap->collector_policy());
325
326 size_policy->decay_supplemental_growth(true /* full gc*/);
327
328 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
329
330 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
331 size_policy->calculated_survivor_size_in_bytes());
332 }
333 if (PrintAdaptiveSizePolicy) {
334 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
335 heap->total_collections());
336 }
337 }
338
339 if (UsePerfData) {
340 heap->gc_policy_counters()->update_counters();
341 heap->gc_policy_counters()->update_old_capacity(
342 old_gen->capacity_in_bytes());
343 heap->gc_policy_counters()->update_young_capacity(
344 young_gen->capacity_in_bytes());
345 }
346
347 heap->resize_all_tlabs();
348
349 // We collected the heap, recalculate the metaspace capacity
350 MetaspaceGC::compute_new_size();
351
352 if (TraceOldGenTime) accumulated_time()->stop();
353
354 if (PrintGC) {
355 if (PrintGCDetails) {
356 // Don't print a GC timestamp here. This is after the GC so
357 // would be confusing.
358 young_gen->print_used_change(young_gen_prev_used);
359 old_gen->print_used_change(old_gen_prev_used);
360 }
361 heap->print_heap_change(prev_used);
362 if (PrintGCDetails) {
363 MetaspaceAux::print_metaspace_change(metadata_prev_used);
364 }
365 }
366
367 // Track memory usage and detect low memory
368 MemoryService::track_memory_usage();
369 heap->update_counters();
370 }
371
372 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
373 HandleMark hm; // Discard invalid handles created during verification
374 Universe::verify(" VerifyAfterGC:");
375 }
376
377 // Re-verify object start arrays
378 if (VerifyObjectStartArray &&
379 VerifyAfterGC) {
380 old_gen->verify_object_start_array();
381 }
382
383 if (ZapUnusedHeapArea) {
384 old_gen->object_space()->check_mangled_unused_area_complete();
385 }
386
387 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
388
389 heap->print_heap_after_gc();
390 heap->trace_heap_after_gc(_gc_tracer);
391
392 heap->post_full_gc_dump(_gc_timer);
393
394 #ifdef TRACESPINNING
395 ParallelTaskTerminator::print_termination_counts();
396 #endif
397
398 _gc_timer->register_gc_end();
399
400 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
401
402 return true;
403 }
404
405 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
406 PSYoungGen* young_gen,
407 PSOldGen* old_gen) {
408 MutableSpace* const eden_space = young_gen->eden_space();
409 assert(!eden_space->is_empty(), "eden must be non-empty");
410 assert(young_gen->virtual_space()->alignment() ==
411 old_gen->virtual_space()->alignment(), "alignments do not match");
412
413 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
414 return false;
415 }
416
417 // Both generations must be completely committed.
418 if (young_gen->virtual_space()->uncommitted_size() != 0) {
419 return false;
420 }
421 if (old_gen->virtual_space()->uncommitted_size() != 0) {
422 return false;
423 }
424
425 // Figure out how much to take from eden. Include the average amount promoted
426 // in the total; otherwise the next young gen GC will simply bail out to a
427 // full GC.
428 const size_t alignment = old_gen->virtual_space()->alignment();
429 const size_t eden_used = eden_space->used_in_bytes();
430 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
431 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
432 const size_t eden_capacity = eden_space->capacity_in_bytes();
433
434 if (absorb_size >= eden_capacity) {
435 return false; // Must leave some space in eden.
436 }
437
438 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
439 if (new_young_size < young_gen->min_gen_size()) {
440 return false; // Respect young gen minimum size.
441 }
442
443 if (TraceAdaptiveGCBoundary && Verbose) {
444 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
445 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
446 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
447 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
448 absorb_size / K,
449 eden_capacity / K, (eden_capacity - absorb_size) / K,
450 young_gen->from_space()->used_in_bytes() / K,
451 young_gen->to_space()->used_in_bytes() / K,
452 young_gen->capacity_in_bytes() / K, new_young_size / K);
453 }
454
455 // Fill the unused part of the old gen.
456 MutableSpace* const old_space = old_gen->object_space();
457 HeapWord* const unused_start = old_space->top();
458 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
459
460 if (unused_words > 0) {
461 if (unused_words < CollectedHeap::min_fill_size()) {
462 return false; // If the old gen cannot be filled, must give up.
463 }
464 CollectedHeap::fill_with_objects(unused_start, unused_words);
465 }
466
467 // Take the live data from eden and set both top and end in the old gen to
468 // eden top. (Need to set end because reset_after_change() mangles the region
469 // from end to virtual_space->high() in debug builds).
470 HeapWord* const new_top = eden_space->top();
471 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
472 absorb_size);
473 young_gen->reset_after_change();
474 old_space->set_top(new_top);
475 old_space->set_end(new_top);
476 old_gen->reset_after_change();
477
478 // Update the object start array for the filler object and the data from eden.
479 ObjectStartArray* const start_array = old_gen->start_array();
480 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
481 start_array->allocate_block(p);
482 }
483
484 // Could update the promoted average here, but it is not typically updated at
485 // full GCs and the value to use is unclear. Something like
486 //
487 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
488
489 size_policy->set_bytes_absorbed_from_eden(absorb_size);
490 return true;
491 }
492
493 void PSMarkSweep::allocate_stacks() {
494 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
495 PSYoungGen* young_gen = heap->young_gen();
496
497 MutableSpace* to_space = young_gen->to_space();
498 _preserved_marks = (PreservedMark*)to_space->top();
499 _preserved_count = 0;
500
501 // We want to calculate the size in bytes first.
502 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
503 // Now divide by the size of a PreservedMark
504 _preserved_count_max /= sizeof(PreservedMark);
505 }
506
507
508 void PSMarkSweep::deallocate_stacks() {
509 _preserved_mark_stack.clear(true);
510 _preserved_oop_stack.clear(true);
511 _marking_stack.clear();
512 _objarray_stack.clear(true);
513 }
514
515 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
516 // Recursively traverse all live objects and mark them
517 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
518
519 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
520
521 // Need to clear claim bits before the tracing starts.
522 ClassLoaderDataGraph::clear_claimed_marks();
523
524 // General strong roots.
525 {
526 ParallelScavengeHeap::ParStrongRootsScope psrs;
527 Universe::oops_do(mark_and_push_closure());
528 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
529 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
530 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
531 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
532 ObjectSynchronizer::oops_do(mark_and_push_closure());
533 FlatProfiler::oops_do(mark_and_push_closure());
534 Management::oops_do(mark_and_push_closure());
535 JvmtiExport::oops_do(mark_and_push_closure());
536 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
537 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
538 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
539 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
540 }
541
542 // Flush marking stack.
543 follow_stack();
544
545 // Process reference objects found during marking
546 {
547 ref_processor()->setup_policy(clear_all_softrefs);
548 const ReferenceProcessorStats& stats =
549 ref_processor()->process_discovered_references(
550 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer, _gc_tracer->gc_id());
551 gc_tracer()->report_gc_reference_stats(stats);
552 }
553
554 // This is the point where the entire marking should have completed.
555 assert(_marking_stack.is_empty(), "Marking should have completed");
556
557 // Unload classes and purge the SystemDictionary.
558 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
559
560 // Unload nmethods.
561 CodeCache::do_unloading(is_alive_closure(), purged_class);
562
563 // Prune dead klasses from subklass/sibling/implementor lists.
564 Klass::clean_weak_klass_links(is_alive_closure());
565
566 // Delete entries for dead interned strings.
567 StringTable::unlink(is_alive_closure());
568
569 // Clean up unreferenced symbols in symbol table.
570 SymbolTable::unlink();
571 _gc_tracer->report_object_count_after_gc(is_alive_closure());
572 }
573
574
575 void PSMarkSweep::mark_sweep_phase2() {
576 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
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 // This should be moved to the shared markSweep code!
595 class PSAlwaysTrueClosure: public BoolObjectClosure {
596 public:
597 bool do_object_b(oop p) { return true; }
598 };
599 static PSAlwaysTrueClosure always_true;
600
601 void PSMarkSweep::mark_sweep_phase3() {
602 // Adjust the pointers to reflect the new locations
603 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
604
605 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
606 PSYoungGen* young_gen = heap->young_gen();
607 PSOldGen* old_gen = heap->old_gen();
608
609 // Need to clear claim bits before the tracing starts.
610 ClassLoaderDataGraph::clear_claimed_marks();
611
612 // General strong roots.
613 Universe::oops_do(adjust_pointer_closure());
614 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
615 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
616 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
617 ObjectSynchronizer::oops_do(adjust_pointer_closure());
618 FlatProfiler::oops_do(adjust_pointer_closure());
619 Management::oops_do(adjust_pointer_closure());
620 JvmtiExport::oops_do(adjust_pointer_closure());
621 SystemDictionary::oops_do(adjust_pointer_closure());
622 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
623
624 // Now adjust pointers in remaining weak roots. (All of which should
625 // have been cleared if they pointed to non-surviving objects.)
626 // Global (weak) JNI handles
627 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
628
629 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
630 CodeCache::blobs_do(&adjust_from_blobs);
631 StringTable::oops_do(adjust_pointer_closure());
632 ref_processor()->weak_oops_do(adjust_pointer_closure());
633 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
634
635 adjust_marks();
636
637 young_gen->adjust_pointers();
638 old_gen->adjust_pointers();
639 }
640
641 void PSMarkSweep::mark_sweep_phase4() {
642 EventMark m("4 compact heap");
643 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
644
645 // All pointers are now adjusted, move objects accordingly
646
647 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
648 PSYoungGen* young_gen = heap->young_gen();
649 PSOldGen* old_gen = heap->old_gen();
650
651 old_gen->compact();
652 young_gen->compact();
653 }
654
655 jlong PSMarkSweep::millis_since_last_gc() {
656 // We need a monotonically non-decreasing time in ms but
657 // os::javaTimeMillis() does not guarantee monotonicity.
658 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
659 jlong ret_val = now - _time_of_last_gc;
660 // XXX See note in genCollectedHeap::millis_since_last_gc().
661 if (ret_val < 0) {
662 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
663 return 0;
664 }
665 return ret_val;
666 }
667
668 void PSMarkSweep::reset_millis_since_last_gc() {
669 // We need a monotonically non-decreasing time in ms but
670 // os::javaTimeMillis() does not guarantee monotonicity.
671 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
672 }