1 /*
2 * Copyright (c) 2001, 2014, 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/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
30 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
31 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
32 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
33 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
34 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
35 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
36 #include "gc_implementation/shared/gcHeapSummary.hpp"
37 #include "gc_implementation/shared/gcTimer.hpp"
38 #include "gc_implementation/shared/gcTrace.hpp"
39 #include "gc_implementation/shared/gcTraceTime.hpp"
40 #include "gc_implementation/shared/isGCActiveMark.hpp"
41 #include "gc_implementation/shared/markSweep.hpp"
42 #include "gc_implementation/shared/spaceDecorator.hpp"
43 #include "gc_interface/gcCause.hpp"
44 #include "memory/gcLocker.inline.hpp"
45 #include "memory/referencePolicy.hpp"
46 #include "memory/referenceProcessor.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 #if INCLUDE_JFR
57 #include "jfr/jfr.hpp"
58 #endif // INCLUDE_JFR
59
60 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
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 = Universe::heap()->reserved_region();
68 _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(!Universe::heap()->is_gc_active(), "not reentrant");
90
91 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::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 (GC_locker::check_active_before_gc()) {
115 return false;
116 }
117
118 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
119 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
120 GCCause::Cause gc_cause = heap->gc_cause();
121
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 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
144
145 heap->print_heap_before_gc();
146 heap->trace_heap_before_gc(_gc_tracer);
147
148 // Fill in TLABs
149 heap->accumulate_statistics_all_tlabs();
150 heap->ensure_parsability(true); // retire TLABs
151
152 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
153 HandleMark hm; // Discard invalid handles created during verification
154 Universe::verify(" VerifyBeforeGC:");
155 }
156
157 // Verify object start arrays
158 if (VerifyObjectStartArray &&
159 VerifyBeforeGC) {
160 old_gen->verify_object_start_array();
161 }
162
163 heap->pre_full_gc_dump(_gc_timer);
164
165 // Filled in below to track the state of the young gen after the collection.
166 bool eden_empty;
167 bool survivors_empty;
168 bool young_gen_empty;
169
170 {
171 HandleMark hm;
172
173 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
174 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer->gc_id());
175 TraceCollectorStats tcs(counters());
176 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
177
178 if (TraceGen1Time) accumulated_time()->start();
179
180 // Let the size policy know we're starting
181 size_policy->major_collection_begin();
182
183 CodeCache::gc_prologue();
184 Threads::gc_prologue();
185 BiasedLocking::preserve_marks();
186
187 // Capture heap size before collection for printing.
188 size_t prev_used = heap->used();
189
190 // Capture metadata size before collection for sizing.
191 size_t metadata_prev_used = MetaspaceAux::used_bytes();
192
193 // For PrintGCDetails
194 size_t old_gen_prev_used = old_gen->used_in_bytes();
195 size_t young_gen_prev_used = young_gen->used_in_bytes();
196
197 allocate_stacks();
198
199 COMPILER2_PRESENT(DerivedPointerTable::clear());
200
201 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
202 ref_processor()->setup_policy(clear_all_softrefs);
203
204 mark_sweep_phase1(clear_all_softrefs);
205
206 mark_sweep_phase2();
207
208 // Don't add any more derived pointers during phase3
209 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
210 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
211
212 mark_sweep_phase3();
213
214 mark_sweep_phase4();
215
216 restore_marks();
217
218 deallocate_stacks();
219
220 if (ZapUnusedHeapArea) {
221 // Do a complete mangle (top to end) because the usage for
222 // scratch does not maintain a top pointer.
223 young_gen->to_space()->mangle_unused_area_complete();
224 }
225
226 eden_empty = young_gen->eden_space()->is_empty();
227 if (!eden_empty) {
228 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
229 }
230
231 // Update heap occupancy information which is used as
232 // input to soft ref clearing policy at the next gc.
233 Universe::update_heap_info_at_gc();
234
235 survivors_empty = young_gen->from_space()->is_empty() &&
236 young_gen->to_space()->is_empty();
237 young_gen_empty = eden_empty && survivors_empty;
238
239 BarrierSet* bs = heap->barrier_set();
240 if (bs->is_a(BarrierSet::ModRef)) {
241 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
242 MemRegion old_mr = heap->old_gen()->reserved();
243 if (young_gen_empty) {
244 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
245 } else {
246 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
247 }
248 }
249
250 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
251 ClassLoaderDataGraph::purge();
252 MetaspaceAux::verify_metrics();
253
254 BiasedLocking::restore_marks();
255 Threads::gc_epilogue();
256 CodeCache::gc_epilogue();
257 JvmtiExport::gc_epilogue();
258
259 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
260
261 ref_processor()->enqueue_discovered_references(NULL);
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 if (PrintAdaptiveSizePolicy) {
272 gclog_or_tty->print("AdaptiveSizeStart: ");
273 gclog_or_tty->stamp();
274 gclog_or_tty->print_cr(" collection: %d ",
275 heap->total_collections());
276 if (Verbose) {
277 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
278 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
279 }
280 }
281
282 // Don't check if the size_policy is ready here. Let
283 // the size_policy check that internally.
284 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
285 ((gc_cause != GCCause::_java_lang_system_gc) ||
286 UseAdaptiveSizePolicyWithSystemGC)) {
287 // Calculate optimal free space amounts
288 assert(young_gen->max_size() >
289 young_gen->from_space()->capacity_in_bytes() +
290 young_gen->to_space()->capacity_in_bytes(),
291 "Sizes of space in young gen are out-of-bounds");
292
293 size_t young_live = young_gen->used_in_bytes();
294 size_t eden_live = young_gen->eden_space()->used_in_bytes();
295 size_t old_live = old_gen->used_in_bytes();
296 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
297 size_t max_old_gen_size = old_gen->max_gen_size();
298 size_t max_eden_size = young_gen->max_size() -
299 young_gen->from_space()->capacity_in_bytes() -
300 young_gen->to_space()->capacity_in_bytes();
301
302 // Used for diagnostics
303 size_policy->clear_generation_free_space_flags();
304
305 size_policy->compute_generations_free_space(young_live,
306 eden_live,
307 old_live,
308 cur_eden,
309 max_old_gen_size,
310 max_eden_size,
311 true /* full gc*/);
312
313 size_policy->check_gc_overhead_limit(young_live,
314 eden_live,
315 max_old_gen_size,
316 max_eden_size,
317 true /* full gc*/,
318 gc_cause,
319 heap->collector_policy());
320
321 size_policy->decay_supplemental_growth(true /* full gc*/);
322
323 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
324
325 // Don't resize the young generation at an major collection. A
326 // desired young generation size may have been calculated but
327 // resizing the young generation complicates the code because the
328 // resizing of the old generation may have moved the boundary
329 // between the young generation and the old generation. Let the
330 // young generation resizing happen at the minor collections.
331 }
332 if (PrintAdaptiveSizePolicy) {
333 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
334 heap->total_collections());
335 }
336 }
337
338 if (UsePerfData) {
339 heap->gc_policy_counters()->update_counters();
340 heap->gc_policy_counters()->update_old_capacity(
341 old_gen->capacity_in_bytes());
342 heap->gc_policy_counters()->update_young_capacity(
343 young_gen->capacity_in_bytes());
344 }
345
346 heap->resize_all_tlabs();
347
348 // We collected the heap, recalculate the metaspace capacity
349 MetaspaceGC::compute_new_size();
350
351 if (TraceGen1Time) accumulated_time()->stop();
352
353 if (PrintGC) {
354 if (PrintGCDetails) {
355 // Don't print a GC timestamp here. This is after the GC so
356 // would be confusing.
357 young_gen->print_used_change(young_gen_prev_used);
358 old_gen->print_used_change(old_gen_prev_used);
359 }
360 heap->print_heap_change(prev_used);
361 if (PrintGCDetails) {
362 MetaspaceAux::print_metaspace_change(metadata_prev_used);
363 }
364 }
365
366 // Track memory usage and detect low memory
367 MemoryService::track_memory_usage();
368 heap->update_counters();
369 }
370
371 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
372 HandleMark hm; // Discard invalid handles created during verification
373 Universe::verify(" VerifyAfterGC:");
374 }
375
376 // Re-verify object start arrays
377 if (VerifyObjectStartArray &&
378 VerifyAfterGC) {
379 old_gen->verify_object_start_array();
380 }
381
382 if (ZapUnusedHeapArea) {
383 old_gen->object_space()->check_mangled_unused_area_complete();
384 }
385
386 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
387
388 heap->print_heap_after_gc();
389 heap->trace_heap_after_gc(_gc_tracer);
390
391 heap->post_full_gc_dump(_gc_timer);
392
393 #ifdef TRACESPINNING
394 ParallelTaskTerminator::print_termination_counts();
395 #endif
396
397 _gc_timer->register_gc_end();
398
399 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
400
401 return true;
402 }
403
404 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
405 PSYoungGen* young_gen,
406 PSOldGen* old_gen) {
407 MutableSpace* const eden_space = young_gen->eden_space();
408 assert(!eden_space->is_empty(), "eden must be non-empty");
409 assert(young_gen->virtual_space()->alignment() ==
410 old_gen->virtual_space()->alignment(), "alignments do not match");
411
412 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
413 return false;
414 }
415
416 // Both generations must be completely committed.
417 if (young_gen->virtual_space()->uncommitted_size() != 0) {
418 return false;
419 }
420 if (old_gen->virtual_space()->uncommitted_size() != 0) {
421 return false;
422 }
423
424 // Figure out how much to take from eden. Include the average amount promoted
425 // in the total; otherwise the next young gen GC will simply bail out to a
426 // full GC.
427 const size_t alignment = old_gen->virtual_space()->alignment();
428 const size_t eden_used = eden_space->used_in_bytes();
429 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
430 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
431 const size_t eden_capacity = eden_space->capacity_in_bytes();
432
433 if (absorb_size >= eden_capacity) {
434 return false; // Must leave some space in eden.
435 }
436
437 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
438 if (new_young_size < young_gen->min_gen_size()) {
439 return false; // Respect young gen minimum size.
440 }
441
442 if (TraceAdaptiveGCBoundary && Verbose) {
443 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
444 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
445 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
446 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
447 absorb_size / K,
448 eden_capacity / K, (eden_capacity - absorb_size) / K,
449 young_gen->from_space()->used_in_bytes() / K,
450 young_gen->to_space()->used_in_bytes() / K,
451 young_gen->capacity_in_bytes() / K, new_young_size / K);
452 }
453
454 // Fill the unused part of the old gen.
455 MutableSpace* const old_space = old_gen->object_space();
456 HeapWord* const unused_start = old_space->top();
457 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
458
459 if (unused_words > 0) {
460 if (unused_words < CollectedHeap::min_fill_size()) {
461 return false; // If the old gen cannot be filled, must give up.
462 }
463 CollectedHeap::fill_with_objects(unused_start, unused_words);
464 }
465
466 // Take the live data from eden and set both top and end in the old gen to
467 // eden top. (Need to set end because reset_after_change() mangles the region
468 // from end to virtual_space->high() in debug builds).
469 HeapWord* const new_top = eden_space->top();
470 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
471 absorb_size);
472 young_gen->reset_after_change();
473 old_space->set_top(new_top);
474 old_space->set_end(new_top);
475 old_gen->reset_after_change();
476
477 // Update the object start array for the filler object and the data from eden.
478 ObjectStartArray* const start_array = old_gen->start_array();
479 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
480 start_array->allocate_block(p);
481 }
482
483 // Could update the promoted average here, but it is not typically updated at
484 // full GCs and the value to use is unclear. Something like
485 //
486 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
487
488 size_policy->set_bytes_absorbed_from_eden(absorb_size);
489 return true;
490 }
491
492 void PSMarkSweep::allocate_stacks() {
493 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
494 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
495
496 PSYoungGen* young_gen = heap->young_gen();
497
498 MutableSpace* to_space = young_gen->to_space();
499 _preserved_marks = (PreservedMark*)to_space->top();
500 _preserved_count = 0;
501
502 // We want to calculate the size in bytes first.
503 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
504 // Now divide by the size of a PreservedMark
505 _preserved_count_max /= sizeof(PreservedMark);
506 }
507
508
509 void PSMarkSweep::deallocate_stacks() {
510 _preserved_mark_stack.clear(true);
511 _preserved_oop_stack.clear(true);
512 _marking_stack.clear();
513 _objarray_stack.clear(true);
514 }
515
516 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
517 // Recursively traverse all live objects and mark them
518 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
519 trace(" 1");
520
521 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
522 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
523
524 // Need to clear claim bits before the tracing starts.
525 ClassLoaderDataGraph::clear_claimed_marks();
526
527 // General strong roots.
528 {
529 ParallelScavengeHeap::ParStrongRootsScope psrs;
530 Universe::oops_do(mark_and_push_closure());
531 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
532 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
533 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
534 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
535 ObjectSynchronizer::oops_do(mark_and_push_closure());
536 FlatProfiler::oops_do(mark_and_push_closure());
537 Management::oops_do(mark_and_push_closure());
538 JvmtiExport::oops_do(mark_and_push_closure());
539 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
540 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
541 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
542 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
543 }
544
545 // Flush marking stack.
546 follow_stack();
547
548 // Process reference objects found during marking
549 {
550 ref_processor()->setup_policy(clear_all_softrefs);
551 const ReferenceProcessorStats& stats =
552 ref_processor()->process_discovered_references(
553 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer, _gc_tracer->gc_id());
554 gc_tracer()->report_gc_reference_stats(stats);
555 }
556
557 // This is the point where the entire marking should have completed.
558 assert(_marking_stack.is_empty(), "Marking should have completed");
559
560 // Unload classes and purge the SystemDictionary.
561 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
562
563 // Unload nmethods.
564 CodeCache::do_unloading(is_alive_closure(), purged_class);
565
566 // Prune dead klasses from subklass/sibling/implementor lists.
567 Klass::clean_weak_klass_links(is_alive_closure());
568
569 // Delete entries for dead interned strings.
570 StringTable::unlink(is_alive_closure());
571
572 // Clean up unreferenced symbols in symbol table.
573 SymbolTable::unlink();
574 _gc_tracer->report_object_count_after_gc(is_alive_closure());
575 }
576
577
578 void PSMarkSweep::mark_sweep_phase2() {
579 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
580 trace("2");
581
582 // Now all live objects are marked, compute the new object addresses.
583
584 // It is not required that we traverse spaces in the same order in
585 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
586 // tracking expects us to do so. See comment under phase4.
587
588 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
589 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
590
591 PSOldGen* old_gen = heap->old_gen();
592
593 // Begin compacting into the old gen
594 PSMarkSweepDecorator::set_destination_decorator_tenured();
595
596 // This will also compact the young gen spaces.
597 old_gen->precompact();
598 }
599
600 // This should be moved to the shared markSweep code!
601 class PSAlwaysTrueClosure: public BoolObjectClosure {
602 public:
603 bool do_object_b(oop p) { return true; }
604 };
605 static PSAlwaysTrueClosure always_true;
606
607 void PSMarkSweep::mark_sweep_phase3() {
608 // Adjust the pointers to reflect the new locations
609 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
610 trace("3");
611
612 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
613 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
614
615 PSYoungGen* young_gen = heap->young_gen();
616 PSOldGen* old_gen = heap->old_gen();
617
618 // Need to clear claim bits before the tracing starts.
619 ClassLoaderDataGraph::clear_claimed_marks();
620
621 // General strong roots.
622 Universe::oops_do(adjust_pointer_closure());
623 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
624 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
625 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
626 ObjectSynchronizer::oops_do(adjust_pointer_closure());
627 FlatProfiler::oops_do(adjust_pointer_closure());
628 Management::oops_do(adjust_pointer_closure());
629 JvmtiExport::oops_do(adjust_pointer_closure());
630 SystemDictionary::oops_do(adjust_pointer_closure());
631 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
632
633 // Now adjust pointers in remaining weak roots. (All of which should
634 // have been cleared if they pointed to non-surviving objects.)
635 // Global (weak) JNI handles
636 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
637 JFR_ONLY(Jfr::weak_oops_do(&always_true, adjust_pointer_closure()));
638
639 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
640 CodeCache::blobs_do(&adjust_from_blobs);
641 StringTable::oops_do(adjust_pointer_closure());
642 ref_processor()->weak_oops_do(adjust_pointer_closure());
643 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
644
645 adjust_marks();
646
647 young_gen->adjust_pointers();
648 old_gen->adjust_pointers();
649 }
650
651 void PSMarkSweep::mark_sweep_phase4() {
652 EventMark m("4 compact heap");
653 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
654 trace("4");
655
656 // All pointers are now adjusted, move objects accordingly
657
658 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
659 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
660
661 PSYoungGen* young_gen = heap->young_gen();
662 PSOldGen* old_gen = heap->old_gen();
663
664 old_gen->compact();
665 young_gen->compact();
666 }
667
668 jlong PSMarkSweep::millis_since_last_gc() {
669 // We need a monotonically non-deccreasing time in ms but
670 // os::javaTimeMillis() does not guarantee monotonicity.
671 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
672 jlong ret_val = now - _time_of_last_gc;
673 // XXX See note in genCollectedHeap::millis_since_last_gc().
674 if (ret_val < 0) {
675 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
676 return 0;
677 }
678 return ret_val;
679 }
680
681 void PSMarkSweep::reset_millis_since_last_gc() {
682 // We need a monotonically non-deccreasing time in ms but
683 // os::javaTimeMillis() does not guarantee monotonicity.
684 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
685 }