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_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 = ParallelScavengeHeap::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(!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 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::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 COMPILER2_PRESENT(DerivedPointerTable::clear());
193
194 ref_processor()->enable_discovery();
195 ref_processor()->setup_policy(clear_all_softrefs);
196
197 mark_sweep_phase1(clear_all_softrefs);
198
199 mark_sweep_phase2();
200
201 // Don't add any more derived pointers during phase3
202 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
203 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
204
205 mark_sweep_phase3();
206
207 mark_sweep_phase4();
208
209 restore_marks();
210
211 deallocate_stacks();
212
213 if (ZapUnusedHeapArea) {
214 // Do a complete mangle (top to end) because the usage for
215 // scratch does not maintain a top pointer.
216 young_gen->to_space()->mangle_unused_area_complete();
217 }
218
219 eden_empty = young_gen->eden_space()->is_empty();
220 if (!eden_empty) {
221 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
222 }
223
224 // Update heap occupancy information which is used as
225 // input to soft ref clearing policy at the next gc.
226 Universe::update_heap_info_at_gc();
227
228 survivors_empty = young_gen->from_space()->is_empty() &&
229 young_gen->to_space()->is_empty();
230 young_gen_empty = eden_empty && survivors_empty;
231
232 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
233 MemRegion old_mr = heap->old_gen()->reserved();
234 if (young_gen_empty) {
235 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
236 } else {
237 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
238 }
239
240 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
241 ClassLoaderDataGraph::purge();
242 MetaspaceAux::verify_metrics();
243
244 BiasedLocking::restore_marks();
245 CodeCache::gc_epilogue();
246 JvmtiExport::gc_epilogue();
247
248 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
249
250 ref_processor()->enqueue_discovered_references(NULL);
251
252 // Update time of last GC
253 reset_millis_since_last_gc();
254
255 // Let the size policy know we're done
256 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
257
258 if (UseAdaptiveSizePolicy) {
259
260 if (PrintAdaptiveSizePolicy) {
261 gclog_or_tty->print("AdaptiveSizeStart: ");
262 gclog_or_tty->stamp();
263 gclog_or_tty->print_cr(" collection: %d ",
264 heap->total_collections());
265 if (Verbose) {
266 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
267 " young_gen_capacity: " SIZE_FORMAT,
268 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
269 }
270 }
271
272 // Don't check if the size_policy is ready here. Let
273 // the size_policy check that internally.
274 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
275 ((gc_cause != GCCause::_java_lang_system_gc) ||
276 UseAdaptiveSizePolicyWithSystemGC)) {
277 // Swap the survivor spaces if from_space is empty. The
278 // resize_young_gen() called below is normally used after
279 // a successful young GC and swapping of survivor spaces;
280 // otherwise, it will fail to resize the young gen with
281 // the current implementation.
282 if (young_gen->from_space()->is_empty()) {
283 young_gen->from_space()->clear(SpaceDecorator::Mangle);
284 young_gen->swap_spaces();
285 }
286
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 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
326 size_policy->calculated_survivor_size_in_bytes());
327 }
328 if (PrintAdaptiveSizePolicy) {
329 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
330 heap->total_collections());
331 }
332 }
333
334 if (UsePerfData) {
335 heap->gc_policy_counters()->update_counters();
336 heap->gc_policy_counters()->update_old_capacity(
337 old_gen->capacity_in_bytes());
338 heap->gc_policy_counters()->update_young_capacity(
339 young_gen->capacity_in_bytes());
340 }
341
342 heap->resize_all_tlabs();
343
344 // We collected the heap, recalculate the metaspace capacity
345 MetaspaceGC::compute_new_size();
346
347 if (TraceOldGenTime) accumulated_time()->stop();
348
349 if (PrintGC) {
350 if (PrintGCDetails) {
351 // Don't print a GC timestamp here. This is after the GC so
352 // would be confusing.
353 young_gen->print_used_change(young_gen_prev_used);
354 old_gen->print_used_change(old_gen_prev_used);
355 }
356 heap->print_heap_change(prev_used);
357 if (PrintGCDetails) {
358 MetaspaceAux::print_metaspace_change(metadata_prev_used);
359 }
360 }
361
362 // Track memory usage and detect low memory
363 MemoryService::track_memory_usage();
364 heap->update_counters();
365 }
366
367 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
368 HandleMark hm; // Discard invalid handles created during verification
369 Universe::verify(" VerifyAfterGC:");
370 }
371
372 // Re-verify object start arrays
373 if (VerifyObjectStartArray &&
374 VerifyAfterGC) {
375 old_gen->verify_object_start_array();
376 }
377
378 if (ZapUnusedHeapArea) {
379 old_gen->object_space()->check_mangled_unused_area_complete();
380 }
381
382 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
383
384 heap->print_heap_after_gc();
385 heap->trace_heap_after_gc(_gc_tracer);
386
387 heap->post_full_gc_dump(_gc_timer);
388
389 #ifdef TRACESPINNING
390 ParallelTaskTerminator::print_termination_counts();
391 #endif
392
393 _gc_timer->register_gc_end();
394
395 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
396
397 return true;
398 }
399
400 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
401 PSYoungGen* young_gen,
402 PSOldGen* old_gen) {
403 MutableSpace* const eden_space = young_gen->eden_space();
404 assert(!eden_space->is_empty(), "eden must be non-empty");
405 assert(young_gen->virtual_space()->alignment() ==
406 old_gen->virtual_space()->alignment(), "alignments do not match");
407
408 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
409 return false;
410 }
411
412 // Both generations must be completely committed.
413 if (young_gen->virtual_space()->uncommitted_size() != 0) {
414 return false;
415 }
416 if (old_gen->virtual_space()->uncommitted_size() != 0) {
417 return false;
418 }
419
420 // Figure out how much to take from eden. Include the average amount promoted
421 // in the total; otherwise the next young gen GC will simply bail out to a
422 // full GC.
423 const size_t alignment = old_gen->virtual_space()->alignment();
424 const size_t eden_used = eden_space->used_in_bytes();
425 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
426 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
427 const size_t eden_capacity = eden_space->capacity_in_bytes();
428
429 if (absorb_size >= eden_capacity) {
430 return false; // Must leave some space in eden.
431 }
432
433 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
434 if (new_young_size < young_gen->min_gen_size()) {
435 return false; // Respect young gen minimum size.
436 }
437
438 if (TraceAdaptiveGCBoundary && Verbose) {
439 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
440 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
441 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
442 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
443 absorb_size / K,
444 eden_capacity / K, (eden_capacity - absorb_size) / K,
445 young_gen->from_space()->used_in_bytes() / K,
446 young_gen->to_space()->used_in_bytes() / K,
447 young_gen->capacity_in_bytes() / K, new_young_size / K);
448 }
449
450 // Fill the unused part of the old gen.
451 MutableSpace* const old_space = old_gen->object_space();
452 HeapWord* const unused_start = old_space->top();
453 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
454
455 if (unused_words > 0) {
456 if (unused_words < CollectedHeap::min_fill_size()) {
457 return false; // If the old gen cannot be filled, must give up.
458 }
459 CollectedHeap::fill_with_objects(unused_start, unused_words);
460 }
461
462 // Take the live data from eden and set both top and end in the old gen to
463 // eden top. (Need to set end because reset_after_change() mangles the region
464 // from end to virtual_space->high() in debug builds).
465 HeapWord* const new_top = eden_space->top();
466 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
467 absorb_size);
468 young_gen->reset_after_change();
469 old_space->set_top(new_top);
470 old_space->set_end(new_top);
471 old_gen->reset_after_change();
472
473 // Update the object start array for the filler object and the data from eden.
474 ObjectStartArray* const start_array = old_gen->start_array();
475 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
476 start_array->allocate_block(p);
477 }
478
479 // Could update the promoted average here, but it is not typically updated at
480 // full GCs and the value to use is unclear. Something like
481 //
482 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
483
484 size_policy->set_bytes_absorbed_from_eden(absorb_size);
485 return true;
486 }
487
488 void PSMarkSweep::allocate_stacks() {
489 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
490 PSYoungGen* young_gen = heap->young_gen();
491
492 MutableSpace* to_space = young_gen->to_space();
493 _preserved_marks = (PreservedMark*)to_space->top();
494 _preserved_count = 0;
495
496 // We want to calculate the size in bytes first.
497 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
498 // Now divide by the size of a PreservedMark
499 _preserved_count_max /= sizeof(PreservedMark);
500 }
501
502
503 void PSMarkSweep::deallocate_stacks() {
504 _preserved_mark_stack.clear(true);
505 _preserved_oop_stack.clear(true);
506 _marking_stack.clear();
507 _objarray_stack.clear(true);
508 }
509
510 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
511 // Recursively traverse all live objects and mark them
512 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
513
514 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
515
516 // Need to clear claim bits before the tracing starts.
517 ClassLoaderDataGraph::clear_claimed_marks();
518
519 // General strong roots.
520 {
521 ParallelScavengeHeap::ParStrongRootsScope psrs;
522 Universe::oops_do(mark_and_push_closure());
523 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
524 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
525 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
526 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
527 ObjectSynchronizer::oops_do(mark_and_push_closure());
528 FlatProfiler::oops_do(mark_and_push_closure());
529 Management::oops_do(mark_and_push_closure());
530 JvmtiExport::oops_do(mark_and_push_closure());
531 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
532 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
533 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
534 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
535 }
536
537 // Flush marking stack.
538 follow_stack();
539
540 // Process reference objects found during marking
541 {
542 ref_processor()->setup_policy(clear_all_softrefs);
543 const ReferenceProcessorStats& stats =
544 ref_processor()->process_discovered_references(
545 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer, _gc_tracer->gc_id());
546 gc_tracer()->report_gc_reference_stats(stats);
547 }
548
549 // This is the point where the entire marking should have completed.
550 assert(_marking_stack.is_empty(), "Marking should have completed");
551
552 // Unload classes and purge the SystemDictionary.
553 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
554
555 // Unload nmethods.
556 CodeCache::do_unloading(is_alive_closure(), purged_class);
557
558 // Prune dead klasses from subklass/sibling/implementor lists.
559 Klass::clean_weak_klass_links(is_alive_closure());
560
561 // Delete entries for dead interned strings.
562 StringTable::unlink(is_alive_closure());
563
564 // Clean up unreferenced symbols in symbol table.
565 SymbolTable::unlink();
566 _gc_tracer->report_object_count_after_gc(is_alive_closure());
567 }
568
569
570 void PSMarkSweep::mark_sweep_phase2() {
571 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
572
573 // Now all live objects are marked, compute the new object addresses.
574
575 // It is not required that we traverse spaces in the same order in
576 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
577 // tracking expects us to do so. See comment under phase4.
578
579 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
580 PSOldGen* old_gen = heap->old_gen();
581
582 // Begin compacting into the old gen
583 PSMarkSweepDecorator::set_destination_decorator_tenured();
584
585 // This will also compact the young gen spaces.
586 old_gen->precompact();
587 }
588
589 // This should be moved to the shared markSweep code!
590 class PSAlwaysTrueClosure: public BoolObjectClosure {
591 public:
592 bool do_object_b(oop p) { return true; }
593 };
594 static PSAlwaysTrueClosure always_true;
595
596 void PSMarkSweep::mark_sweep_phase3() {
597 // Adjust the pointers to reflect the new locations
598 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
599
600 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
601 PSYoungGen* young_gen = heap->young_gen();
602 PSOldGen* old_gen = heap->old_gen();
603
604 // Need to clear claim bits before the tracing starts.
605 ClassLoaderDataGraph::clear_claimed_marks();
606
607 // General strong roots.
608 Universe::oops_do(adjust_pointer_closure());
609 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
610 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
611 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
612 ObjectSynchronizer::oops_do(adjust_pointer_closure());
613 FlatProfiler::oops_do(adjust_pointer_closure());
614 Management::oops_do(adjust_pointer_closure());
615 JvmtiExport::oops_do(adjust_pointer_closure());
616 SystemDictionary::oops_do(adjust_pointer_closure());
617 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
618
619 // Now adjust pointers in remaining weak roots. (All of which should
620 // have been cleared if they pointed to non-surviving objects.)
621 // Global (weak) JNI handles
622 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
623
624 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
625 CodeCache::blobs_do(&adjust_from_blobs);
626 StringTable::oops_do(adjust_pointer_closure());
627 ref_processor()->weak_oops_do(adjust_pointer_closure());
628 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
629
630 adjust_marks();
631
632 young_gen->adjust_pointers();
633 old_gen->adjust_pointers();
634 }
635
636 void PSMarkSweep::mark_sweep_phase4() {
637 EventMark m("4 compact heap");
638 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
639
640 // All pointers are now adjusted, move objects accordingly
641
642 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
643 PSYoungGen* young_gen = heap->young_gen();
644 PSOldGen* old_gen = heap->old_gen();
645
646 old_gen->compact();
647 young_gen->compact();
648 }
649
650 jlong PSMarkSweep::millis_since_last_gc() {
651 // We need a monotonically non-decreasing time in ms but
652 // os::javaTimeMillis() does not guarantee monotonicity.
653 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
654 jlong ret_val = now - _time_of_last_gc;
655 // XXX See note in genCollectedHeap::millis_since_last_gc().
656 if (ret_val < 0) {
657 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
658 return 0;
659 }
660 return ret_val;
661 }
662
663 void PSMarkSweep::reset_millis_since_last_gc() {
664 // We need a monotonically non-decreasing time in ms but
665 // os::javaTimeMillis() does not guarantee monotonicity.
666 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
667 }