1 /*
2 * Copyright (c) 2001, 2013, 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
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 = Universe::heap()->reserved_region();
63 _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(!Universe::heap()->is_gc_active(), "not reentrant");
85
86 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::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 UIntFlagSetting 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*)Universe::heap();
114 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
115 GCCause::Cause gc_cause = heap->gc_cause();
116
117 _gc_timer->register_gc_start();
118 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
119
120 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
121
122 // The scope of casr should end after code that can change
123 // CollectorPolicy::_should_clear_all_soft_refs.
124 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
125
126 PSYoungGen* young_gen = heap->young_gen();
127 PSOldGen* old_gen = heap->old_gen();
128
129 // Increment the invocation count
130 heap->increment_total_collections(true /* full */);
131
132 // Save information needed to minimize mangling
133 heap->record_gen_tops_before_GC();
134
135 // We need to track unique mark sweep invocations as well.
136 _total_invocations++;
137
138 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
139
140 heap->print_heap_before_gc();
141 heap->trace_heap_before_gc(_gc_tracer);
142
143 // Fill in TLABs
144 heap->accumulate_statistics_all_tlabs();
145 heap->ensure_parsability(true); // retire TLABs
146
147 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
148 HandleMark hm; // Discard invalid handles created during verification
149 Universe::verify(" VerifyBeforeGC:");
150 }
151
152 // Verify object start arrays
153 if (VerifyObjectStartArray &&
154 VerifyBeforeGC) {
155 old_gen->verify_object_start_array();
156 }
157
158 heap->pre_full_gc_dump(_gc_timer);
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 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
169 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
170 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
171 TraceCollectorStats tcs(counters());
172 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
173
174 if (TraceGen1Time) accumulated_time()->start();
175
176 // Let the size policy know we're starting
177 size_policy->major_collection_begin();
178
179 CodeCache::gc_prologue();
180 Threads::gc_prologue();
181 BiasedLocking::preserve_marks();
182
183 // Capture heap size before collection for printing.
184 size_t prev_used = heap->used();
185
186 // Capture metadata size before collection for sizing.
187 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
188
189 // For PrintGCDetails
190 size_t old_gen_prev_used = old_gen->used_in_bytes();
191 size_t young_gen_prev_used = young_gen->used_in_bytes();
192
193 allocate_stacks();
194
195 COMPILER2_PRESENT(DerivedPointerTable::clear());
196
197 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
198 ref_processor()->setup_policy(clear_all_softrefs);
199
200 mark_sweep_phase1(clear_all_softrefs);
201
202 mark_sweep_phase2();
203
204 // Don't add any more derived pointers during phase3
205 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
206 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
207
208 mark_sweep_phase3();
209
210 mark_sweep_phase4();
211
212 restore_marks();
213
214 deallocate_stacks();
215
216 if (ZapUnusedHeapArea) {
217 // Do a complete mangle (top to end) because the usage for
218 // scratch does not maintain a top pointer.
219 young_gen->to_space()->mangle_unused_area_complete();
220 }
221
222 eden_empty = young_gen->eden_space()->is_empty();
223 if (!eden_empty) {
224 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
225 }
226
227 // Update heap occupancy information which is used as
228 // input to soft ref clearing policy at the next gc.
229 Universe::update_heap_info_at_gc();
230
231 survivors_empty = young_gen->from_space()->is_empty() &&
232 young_gen->to_space()->is_empty();
233 young_gen_empty = eden_empty && survivors_empty;
234
235 BarrierSet* bs = heap->barrier_set();
236 if (bs->is_a(BarrierSet::ModRef)) {
237 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
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
246 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
247 ClassLoaderDataGraph::purge();
248 MetaspaceAux::verify_metrics();
249
250 BiasedLocking::restore_marks();
251 Threads::gc_epilogue();
252 CodeCache::gc_epilogue();
253 JvmtiExport::gc_epilogue();
254
255 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
256
257 ref_processor()->enqueue_discovered_references(NULL);
258
259 // Update time of last GC
260 reset_millis_since_last_gc();
261
262 // Let the size policy know we're done
263 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
264
265 if (UseAdaptiveSizePolicy) {
266
267 if (PrintAdaptiveSizePolicy) {
268 gclog_or_tty->print("AdaptiveSizeStart: ");
269 gclog_or_tty->stamp();
270 gclog_or_tty->print_cr(" collection: %d ",
271 heap->total_collections());
272 if (Verbose) {
273 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
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 ((gc_cause != GCCause::_java_lang_system_gc) ||
282 UseAdaptiveSizePolicyWithSystemGC)) {
283 // Swap the survivor spaces if from_space is empty. The
284 // resize_young_gen() called below is normally used after
285 // a successful young GC and swapping of survivor spaces;
286 // otherwise, it will fail to resize the young gen with
287 // the current implementation.
288 if (young_gen->from_space()->is_empty()) {
289 young_gen->from_space()->clear(SpaceDecorator::Mangle);
290 young_gen->swap_spaces();
291 }
292
293 // Calculate optimal free space amounts
294 assert(young_gen->max_size() >
295 young_gen->from_space()->capacity_in_bytes() +
296 young_gen->to_space()->capacity_in_bytes(),
297 "Sizes of space in young gen are out-of-bounds");
298
299 size_t young_live = young_gen->used_in_bytes();
300 size_t eden_live = young_gen->eden_space()->used_in_bytes();
301 size_t old_live = old_gen->used_in_bytes();
302 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
303 size_t max_old_gen_size = old_gen->max_gen_size();
304 size_t max_eden_size = young_gen->max_size() -
305 young_gen->from_space()->capacity_in_bytes() -
306 young_gen->to_space()->capacity_in_bytes();
307
308 // Used for diagnostics
309 size_policy->clear_generation_free_space_flags();
310
311 size_policy->compute_generations_free_space(young_live,
312 eden_live,
313 old_live,
314 cur_eden,
315 max_old_gen_size,
316 max_eden_size,
317 true /* full gc*/);
318
319 size_policy->check_gc_overhead_limit(young_live,
320 eden_live,
321 max_old_gen_size,
322 max_eden_size,
323 true /* full gc*/,
324 gc_cause,
325 heap->collector_policy());
326
327 size_policy->decay_supplemental_growth(true /* full gc*/);
328
329 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
330
331 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
332 size_policy->calculated_survivor_size_in_bytes());
333 }
334 if (PrintAdaptiveSizePolicy) {
335 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
336 heap->total_collections());
337 }
338 }
339
340 if (UsePerfData) {
341 heap->gc_policy_counters()->update_counters();
342 heap->gc_policy_counters()->update_old_capacity(
343 old_gen->capacity_in_bytes());
344 heap->gc_policy_counters()->update_young_capacity(
345 young_gen->capacity_in_bytes());
346 }
347
348 heap->resize_all_tlabs();
349
350 // We collected the heap, recalculate the metaspace capacity
351 MetaspaceGC::compute_new_size();
352
353 if (TraceGen1Time) accumulated_time()->stop();
354
355 if (PrintGC) {
356 if (PrintGCDetails) {
357 // Don't print a GC timestamp here. This is after the GC so
358 // would be confusing.
359 young_gen->print_used_change(young_gen_prev_used);
360 old_gen->print_used_change(old_gen_prev_used);
361 }
362 heap->print_heap_change(prev_used);
363 if (PrintGCDetails) {
364 MetaspaceAux::print_metaspace_change(metadata_prev_used);
365 }
366 }
367
368 // Track memory usage and detect low memory
369 MemoryService::track_memory_usage();
370 heap->update_counters();
371 }
372
373 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
374 HandleMark hm; // Discard invalid handles created during verification
375 Universe::verify(" VerifyAfterGC:");
376 }
377
378 // Re-verify object start arrays
379 if (VerifyObjectStartArray &&
380 VerifyAfterGC) {
381 old_gen->verify_object_start_array();
382 }
383
384 if (ZapUnusedHeapArea) {
385 old_gen->object_space()->check_mangled_unused_area_complete();
386 }
387
388 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
389
390 heap->print_heap_after_gc();
391 heap->trace_heap_after_gc(_gc_tracer);
392
393 heap->post_full_gc_dump(_gc_timer);
394
395 #ifdef TRACESPINNING
396 ParallelTaskTerminator::print_termination_counts();
397 #endif
398
399 _gc_timer->register_gc_end();
400
401 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
402
403 return true;
404 }
405
406 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
407 PSYoungGen* young_gen,
408 PSOldGen* old_gen) {
409 MutableSpace* const eden_space = young_gen->eden_space();
410 assert(!eden_space->is_empty(), "eden must be non-empty");
411 assert(young_gen->virtual_space()->alignment() ==
412 old_gen->virtual_space()->alignment(), "alignments do not match");
413
414 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
415 return false;
416 }
417
418 // Both generations must be completely committed.
419 if (young_gen->virtual_space()->uncommitted_size() != 0) {
420 return false;
421 }
422 if (old_gen->virtual_space()->uncommitted_size() != 0) {
423 return false;
424 }
425
426 // Figure out how much to take from eden. Include the average amount promoted
427 // in the total; otherwise the next young gen GC will simply bail out to a
428 // full GC.
429 const size_t alignment = old_gen->virtual_space()->alignment();
430 const size_t eden_used = eden_space->used_in_bytes();
431 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
432 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
433 const size_t eden_capacity = eden_space->capacity_in_bytes();
434
435 if (absorb_size >= eden_capacity) {
436 return false; // Must leave some space in eden.
437 }
438
439 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
440 if (new_young_size < young_gen->min_gen_size()) {
441 return false; // Respect young gen minimum size.
442 }
443
444 if (TraceAdaptiveGCBoundary && Verbose) {
445 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
446 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
447 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
448 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
449 absorb_size / K,
450 eden_capacity / K, (eden_capacity - absorb_size) / K,
451 young_gen->from_space()->used_in_bytes() / K,
452 young_gen->to_space()->used_in_bytes() / K,
453 young_gen->capacity_in_bytes() / K, new_young_size / K);
454 }
455
456 // Fill the unused part of the old gen.
457 MutableSpace* const old_space = old_gen->object_space();
458 HeapWord* const unused_start = old_space->top();
459 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
460
461 if (unused_words > 0) {
462 if (unused_words < CollectedHeap::min_fill_size()) {
463 return false; // If the old gen cannot be filled, must give up.
464 }
465 CollectedHeap::fill_with_objects(unused_start, unused_words);
466 }
467
468 // Take the live data from eden and set both top and end in the old gen to
469 // eden top. (Need to set end because reset_after_change() mangles the region
470 // from end to virtual_space->high() in debug builds).
471 HeapWord* const new_top = eden_space->top();
472 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
473 absorb_size);
474 young_gen->reset_after_change();
475 old_space->set_top(new_top);
476 old_space->set_end(new_top);
477 old_gen->reset_after_change();
478
479 // Update the object start array for the filler object and the data from eden.
480 ObjectStartArray* const start_array = old_gen->start_array();
481 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
482 start_array->allocate_block(p);
483 }
484
485 // Could update the promoted average here, but it is not typically updated at
486 // full GCs and the value to use is unclear. Something like
487 //
488 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
489
490 size_policy->set_bytes_absorbed_from_eden(absorb_size);
491 return true;
492 }
493
494 void PSMarkSweep::allocate_stacks() {
495 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
496 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
497
498 PSYoungGen* young_gen = heap->young_gen();
499
500 MutableSpace* to_space = young_gen->to_space();
501 _preserved_marks = (PreservedMark*)to_space->top();
502 _preserved_count = 0;
503
504 // We want to calculate the size in bytes first.
505 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
506 // Now divide by the size of a PreservedMark
507 _preserved_count_max /= sizeof(PreservedMark);
508 }
509
510
511 void PSMarkSweep::deallocate_stacks() {
512 _preserved_mark_stack.clear(true);
513 _preserved_oop_stack.clear(true);
514 _marking_stack.clear();
515 _objarray_stack.clear(true);
516 }
517
518 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
519 // Recursively traverse all live objects and mark them
520 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer);
521 trace(" 1");
522
523 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
524 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
525
526 // Need to clear claim bits before the tracing starts.
527 ClassLoaderDataGraph::clear_claimed_marks();
528
529 // General strong roots.
530 {
531 ParallelScavengeHeap::ParStrongRootsScope psrs;
532 Universe::oops_do(mark_and_push_closure());
533 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
534 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
535 CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
536 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
537 ObjectSynchronizer::oops_do(mark_and_push_closure());
538 FlatProfiler::oops_do(mark_and_push_closure());
539 Management::oops_do(mark_and_push_closure());
540 JvmtiExport::oops_do(mark_and_push_closure());
541 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
542 ClassLoaderDataGraph::always_strong_oops_do(mark_and_push_closure(), follow_klass_closure(), true);
543 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
544 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
545 }
546
547 // Flush marking stack.
548 follow_stack();
549
550 // Process reference objects found during marking
551 {
552 ref_processor()->setup_policy(clear_all_softrefs);
553 const ReferenceProcessorStats& stats =
554 ref_processor()->process_discovered_references(
555 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer);
556 gc_tracer()->report_gc_reference_stats(stats);
557 }
558
559 // This is the point where the entire marking should have completed.
560 assert(_marking_stack.is_empty(), "Marking should have completed");
561
562 // Unload classes and purge the SystemDictionary.
563 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
564
565 // Unload nmethods.
566 CodeCache::do_unloading(is_alive_closure(), purged_class);
567
568 // Prune dead klasses from subklass/sibling/implementor lists.
569 Klass::clean_weak_klass_links(is_alive_closure());
570
571 // Delete entries for dead interned strings.
572 StringTable::unlink(is_alive_closure());
573
574 // Clean up unreferenced symbols in symbol table.
575 SymbolTable::unlink();
576 _gc_tracer->report_object_count_after_gc(is_alive_closure());
577 }
578
579
580 void PSMarkSweep::mark_sweep_phase2() {
581 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer);
582 trace("2");
583
584 // Now all live objects are marked, compute the new object addresses.
585
586 // It is not required that we traverse spaces in the same order in
587 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
588 // tracking expects us to do so. See comment under phase4.
589
590 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
591 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
592
593 PSOldGen* old_gen = heap->old_gen();
594
595 // Begin compacting into the old gen
596 PSMarkSweepDecorator::set_destination_decorator_tenured();
597
598 // This will also compact the young gen spaces.
599 old_gen->precompact();
600 }
601
602 // This should be moved to the shared markSweep code!
603 class PSAlwaysTrueClosure: public BoolObjectClosure {
604 public:
605 bool do_object_b(oop p) { return true; }
606 };
607 static PSAlwaysTrueClosure always_true;
608
609 void PSMarkSweep::mark_sweep_phase3() {
610 // Adjust the pointers to reflect the new locations
611 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer);
612 trace("3");
613
614 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
615 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
616
617 PSYoungGen* young_gen = heap->young_gen();
618 PSOldGen* old_gen = heap->old_gen();
619
620 // Need to clear claim bits before the tracing starts.
621 ClassLoaderDataGraph::clear_claimed_marks();
622
623 // General strong roots.
624 Universe::oops_do(adjust_pointer_closure());
625 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
626 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
627 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
628 ObjectSynchronizer::oops_do(adjust_pointer_closure());
629 FlatProfiler::oops_do(adjust_pointer_closure());
630 Management::oops_do(adjust_pointer_closure());
631 JvmtiExport::oops_do(adjust_pointer_closure());
632 // SO_AllClasses
633 SystemDictionary::oops_do(adjust_pointer_closure());
634 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
635
636 // Now adjust pointers in remaining weak roots. (All of which should
637 // have been cleared if they pointed to non-surviving objects.)
638 // Global (weak) JNI handles
639 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
640
641 CodeCache::oops_do(adjust_pointer_closure());
642 StringTable::oops_do(adjust_pointer_closure());
643 ref_processor()->weak_oops_do(adjust_pointer_closure());
644 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
645
646 adjust_marks();
647
648 young_gen->adjust_pointers();
649 old_gen->adjust_pointers();
650 }
651
652 void PSMarkSweep::mark_sweep_phase4() {
653 EventMark m("4 compact heap");
654 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer);
655 trace("4");
656
657 // All pointers are now adjusted, move objects accordingly
658
659 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
660 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
661
662 PSYoungGen* young_gen = heap->young_gen();
663 PSOldGen* old_gen = heap->old_gen();
664
665 old_gen->compact();
666 young_gen->compact();
667 }
668
669 jlong PSMarkSweep::millis_since_last_gc() {
670 // We need a monotonically non-decreasing time in ms but
671 // os::javaTimeMillis() does not guarantee monotonicity.
672 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
673 jlong ret_val = now - _time_of_last_gc;
674 // XXX See note in genCollectedHeap::millis_since_last_gc().
675 if (ret_val < 0) {
676 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
677 return 0;
678 }
679 return ret_val;
680 }
681
682 void PSMarkSweep::reset_millis_since_last_gc() {
683 // We need a monotonically non-decreasing time in ms but
684 // os::javaTimeMillis() does not guarantee monotonicity.
685 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
686 }