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 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 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
276 // Swap the survivor spaces if from_space is empty. The
277 // resize_young_gen() called below is normally used after
278 // a successful young GC and swapping of survivor spaces;
279 // otherwise, it will fail to resize the young gen with
280 // the current implementation.
281 if (young_gen->from_space()->is_empty()) {
282 young_gen->from_space()->clear(SpaceDecorator::Mangle);
283 young_gen->swap_spaces();
284 }
285
286 // Calculate optimal free space amounts
287 assert(young_gen->max_size() >
288 young_gen->from_space()->capacity_in_bytes() +
289 young_gen->to_space()->capacity_in_bytes(),
290 "Sizes of space in young gen are out-of-bounds");
291
292 size_t young_live = young_gen->used_in_bytes();
293 size_t eden_live = young_gen->eden_space()->used_in_bytes();
294 size_t old_live = old_gen->used_in_bytes();
295 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
296 size_t max_old_gen_size = old_gen->max_gen_size();
297 size_t max_eden_size = young_gen->max_size() -
298 young_gen->from_space()->capacity_in_bytes() -
299 young_gen->to_space()->capacity_in_bytes();
300
301 // Used for diagnostics
302 size_policy->clear_generation_free_space_flags();
303
304 size_policy->compute_generations_free_space(young_live,
305 eden_live,
306 old_live,
307 cur_eden,
308 max_old_gen_size,
309 max_eden_size,
310 true /* full gc*/);
311
312 size_policy->check_gc_overhead_limit(young_live,
313 eden_live,
314 max_old_gen_size,
315 max_eden_size,
316 true /* full gc*/,
317 gc_cause,
318 heap->collector_policy());
319
320 size_policy->decay_supplemental_growth(true /* full gc*/);
321
322 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
323
324 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
325 size_policy->calculated_survivor_size_in_bytes());
326 }
327 if (PrintAdaptiveSizePolicy) {
328 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
329 heap->total_collections());
330 }
331 }
332
333 if (UsePerfData) {
334 heap->gc_policy_counters()->update_counters();
335 heap->gc_policy_counters()->update_old_capacity(
336 old_gen->capacity_in_bytes());
337 heap->gc_policy_counters()->update_young_capacity(
338 young_gen->capacity_in_bytes());
339 }
340
341 heap->resize_all_tlabs();
342
343 // We collected the heap, recalculate the metaspace capacity
344 MetaspaceGC::compute_new_size();
345
346 if (TraceOldGenTime) accumulated_time()->stop();
347
348 if (PrintGC) {
349 if (PrintGCDetails) {
350 // Don't print a GC timestamp here. This is after the GC so
351 // would be confusing.
352 young_gen->print_used_change(young_gen_prev_used);
353 old_gen->print_used_change(old_gen_prev_used);
354 }
355 heap->print_heap_change(prev_used);
356 if (PrintGCDetails) {
357 MetaspaceAux::print_metaspace_change(metadata_prev_used);
358 }
359 }
360
361 // Track memory usage and detect low memory
362 MemoryService::track_memory_usage();
363 heap->update_counters();
364 }
365
366 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
367 HandleMark hm; // Discard invalid handles created during verification
368 Universe::verify(" VerifyAfterGC:");
369 }
370
371 // Re-verify object start arrays
372 if (VerifyObjectStartArray &&
373 VerifyAfterGC) {
374 old_gen->verify_object_start_array();
375 }
376
377 if (ZapUnusedHeapArea) {
378 old_gen->object_space()->check_mangled_unused_area_complete();
379 }
380
381 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
382
383 heap->print_heap_after_gc();
384 heap->trace_heap_after_gc(_gc_tracer);
385
386 heap->post_full_gc_dump(_gc_timer);
387
388 #ifdef TRACESPINNING
389 ParallelTaskTerminator::print_termination_counts();
390 #endif
391
392 _gc_timer->register_gc_end();
393
394 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
395
396 return true;
397 }
398
399 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
400 PSYoungGen* young_gen,
401 PSOldGen* old_gen) {
402 MutableSpace* const eden_space = young_gen->eden_space();
403 assert(!eden_space->is_empty(), "eden must be non-empty");
404 assert(young_gen->virtual_space()->alignment() ==
405 old_gen->virtual_space()->alignment(), "alignments do not match");
406
407 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
408 return false;
409 }
410
411 // Both generations must be completely committed.
412 if (young_gen->virtual_space()->uncommitted_size() != 0) {
413 return false;
414 }
415 if (old_gen->virtual_space()->uncommitted_size() != 0) {
416 return false;
417 }
418
419 // Figure out how much to take from eden. Include the average amount promoted
420 // in the total; otherwise the next young gen GC will simply bail out to a
421 // full GC.
422 const size_t alignment = old_gen->virtual_space()->alignment();
423 const size_t eden_used = eden_space->used_in_bytes();
424 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
425 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
426 const size_t eden_capacity = eden_space->capacity_in_bytes();
427
428 if (absorb_size >= eden_capacity) {
429 return false; // Must leave some space in eden.
430 }
431
432 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
433 if (new_young_size < young_gen->min_gen_size()) {
434 return false; // Respect young gen minimum size.
435 }
436
437 if (TraceAdaptiveGCBoundary && Verbose) {
438 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
439 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
440 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
441 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
442 absorb_size / K,
443 eden_capacity / K, (eden_capacity - absorb_size) / K,
444 young_gen->from_space()->used_in_bytes() / K,
445 young_gen->to_space()->used_in_bytes() / K,
446 young_gen->capacity_in_bytes() / K, new_young_size / K);
447 }
448
449 // Fill the unused part of the old gen.
450 MutableSpace* const old_space = old_gen->object_space();
451 HeapWord* const unused_start = old_space->top();
452 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
453
454 if (unused_words > 0) {
455 if (unused_words < CollectedHeap::min_fill_size()) {
456 return false; // If the old gen cannot be filled, must give up.
457 }
458 CollectedHeap::fill_with_objects(unused_start, unused_words);
459 }
460
461 // Take the live data from eden and set both top and end in the old gen to
462 // eden top. (Need to set end because reset_after_change() mangles the region
463 // from end to virtual_space->high() in debug builds).
464 HeapWord* const new_top = eden_space->top();
465 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
466 absorb_size);
467 young_gen->reset_after_change();
468 old_space->set_top(new_top);
469 old_space->set_end(new_top);
470 old_gen->reset_after_change();
471
472 // Update the object start array for the filler object and the data from eden.
473 ObjectStartArray* const start_array = old_gen->start_array();
474 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
475 start_array->allocate_block(p);
476 }
477
478 // Could update the promoted average here, but it is not typically updated at
479 // full GCs and the value to use is unclear. Something like
480 //
481 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
482
483 size_policy->set_bytes_absorbed_from_eden(absorb_size);
484 return true;
485 }
486
487 void PSMarkSweep::allocate_stacks() {
488 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
489 PSYoungGen* young_gen = heap->young_gen();
490
491 MutableSpace* to_space = young_gen->to_space();
492 _preserved_marks = (PreservedMark*)to_space->top();
493 _preserved_count = 0;
494
495 // We want to calculate the size in bytes first.
496 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
497 // Now divide by the size of a PreservedMark
498 _preserved_count_max /= sizeof(PreservedMark);
499 }
500
501
502 void PSMarkSweep::deallocate_stacks() {
503 _preserved_mark_stack.clear(true);
504 _preserved_oop_stack.clear(true);
505 _marking_stack.clear();
506 _objarray_stack.clear(true);
507 }
508
509 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
510 // Recursively traverse all live objects and mark them
511 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
512
513 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
514
515 // Need to clear claim bits before the tracing starts.
516 ClassLoaderDataGraph::clear_claimed_marks();
517
518 // General strong roots.
519 {
520 ParallelScavengeHeap::ParStrongRootsScope psrs;
521 Universe::oops_do(mark_and_push_closure());
522 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
523 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
524 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
525 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
526 ObjectSynchronizer::oops_do(mark_and_push_closure());
527 FlatProfiler::oops_do(mark_and_push_closure());
528 Management::oops_do(mark_and_push_closure());
529 JvmtiExport::oops_do(mark_and_push_closure());
530 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
531 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
532 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
533 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
534 }
535
536 // Flush marking stack.
537 follow_stack();
538
539 // Process reference objects found during marking
540 {
541 ref_processor()->setup_policy(clear_all_softrefs);
542 const ReferenceProcessorStats& stats =
543 ref_processor()->process_discovered_references(
544 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer, _gc_tracer->gc_id());
545 gc_tracer()->report_gc_reference_stats(stats);
546 }
547
548 // This is the point where the entire marking should have completed.
549 assert(_marking_stack.is_empty(), "Marking should have completed");
550
551 // Unload classes and purge the SystemDictionary.
552 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
553
554 // Unload nmethods.
555 CodeCache::do_unloading(is_alive_closure(), purged_class);
556
557 // Prune dead klasses from subklass/sibling/implementor lists.
558 Klass::clean_weak_klass_links(is_alive_closure());
559
560 // Delete entries for dead interned strings.
561 StringTable::unlink(is_alive_closure());
562
563 // Clean up unreferenced symbols in symbol table.
564 SymbolTable::unlink();
565 _gc_tracer->report_object_count_after_gc(is_alive_closure());
566 }
567
568
569 void PSMarkSweep::mark_sweep_phase2() {
570 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
571
572 // Now all live objects are marked, compute the new object addresses.
573
574 // It is not required that we traverse spaces in the same order in
575 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
576 // tracking expects us to do so. See comment under phase4.
577
578 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
579 PSOldGen* old_gen = heap->old_gen();
580
581 // Begin compacting into the old gen
582 PSMarkSweepDecorator::set_destination_decorator_tenured();
583
584 // This will also compact the young gen spaces.
585 old_gen->precompact();
586 }
587
588 // This should be moved to the shared markSweep code!
589 class PSAlwaysTrueClosure: public BoolObjectClosure {
590 public:
591 bool do_object_b(oop p) { return true; }
592 };
593 static PSAlwaysTrueClosure always_true;
594
595 void PSMarkSweep::mark_sweep_phase3() {
596 // Adjust the pointers to reflect the new locations
597 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
598
599 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
600 PSYoungGen* young_gen = heap->young_gen();
601 PSOldGen* old_gen = heap->old_gen();
602
603 // Need to clear claim bits before the tracing starts.
604 ClassLoaderDataGraph::clear_claimed_marks();
605
606 // General strong roots.
607 Universe::oops_do(adjust_pointer_closure());
608 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
609 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
610 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
611 ObjectSynchronizer::oops_do(adjust_pointer_closure());
612 FlatProfiler::oops_do(adjust_pointer_closure());
613 Management::oops_do(adjust_pointer_closure());
614 JvmtiExport::oops_do(adjust_pointer_closure());
615 SystemDictionary::oops_do(adjust_pointer_closure());
616 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
617
618 // Now adjust pointers in remaining weak roots. (All of which should
619 // have been cleared if they pointed to non-surviving objects.)
620 // Global (weak) JNI handles
621 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
622
623 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
624 CodeCache::blobs_do(&adjust_from_blobs);
625 StringTable::oops_do(adjust_pointer_closure());
626 ref_processor()->weak_oops_do(adjust_pointer_closure());
627 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
628
629 adjust_marks();
630
631 young_gen->adjust_pointers();
632 old_gen->adjust_pointers();
633 }
634
635 void PSMarkSweep::mark_sweep_phase4() {
636 EventMark m("4 compact heap");
637 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
638
639 // All pointers are now adjusted, move objects accordingly
640
641 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
642 PSYoungGen* young_gen = heap->young_gen();
643 PSOldGen* old_gen = heap->old_gen();
644
645 old_gen->compact();
646 young_gen->compact();
647 }
648
649 jlong PSMarkSweep::millis_since_last_gc() {
650 // We need a monotonically non-decreasing time in ms but
651 // os::javaTimeMillis() does not guarantee monotonicity.
652 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
653 jlong ret_val = now - _time_of_last_gc;
654 // XXX See note in genCollectedHeap::millis_since_last_gc().
655 if (ret_val < 0) {
656 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
657 return 0;
658 }
659 return ret_val;
660 }
661
662 void PSMarkSweep::reset_millis_since_last_gc() {
663 // We need a monotonically non-decreasing time in ms but
664 // os::javaTimeMillis() does not guarantee monotonicity.
665 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
666 }