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/gcId.hpp"
40 #include "gc/shared/gcLocker.inline.hpp"
41 #include "gc/shared/gcTimer.hpp"
42 #include "gc/shared/gcTrace.hpp"
43 #include "gc/shared/gcTraceTime.hpp"
44 #include "gc/shared/isGCActiveMark.hpp"
45 #include "gc/shared/referencePolicy.hpp"
46 #include "gc/shared/referenceProcessor.hpp"
47 #include "gc/shared/spaceDecorator.hpp"
48 #include "oops/oop.inline.hpp"
49 #include "runtime/biasedLocking.hpp"
50 #include "runtime/fprofiler.hpp"
51 #include "runtime/safepoint.hpp"
52 #include "runtime/vmThread.hpp"
53 #include "services/management.hpp"
54 #include "services/memoryService.hpp"
55 #include "utilities/events.hpp"
56 #include "utilities/stack.inline.hpp"
57
58 elapsedTimer PSMarkSweep::_accumulated_time;
59 jlong PSMarkSweep::_time_of_last_gc = 0;
60 CollectorCounters* PSMarkSweep::_counters = NULL;
61
62 void PSMarkSweep::initialize() {
63 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region();
64 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc
65 _counters = new CollectorCounters("PSMarkSweep", 1);
66 }
67
68 // This method contains all heap specific policy for invoking mark sweep.
69 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
70 // the heap. It will do nothing further. If we need to bail out for policy
71 // reasons, scavenge before full gc, or any other specialized behavior, it
72 // needs to be added here.
73 //
74 // Note that this method should only be called from the vm_thread while
75 // at a safepoint!
76 //
77 // Note that the all_soft_refs_clear flag in the collector policy
78 // may be true because this method can be called without intervening
79 // activity. For example when the heap space is tight and full measure
80 // are being taken to free space.
81
82 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
83 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
84 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
85 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
86
87 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
88 GCCause::Cause gc_cause = heap->gc_cause();
89 PSAdaptiveSizePolicy* policy = heap->size_policy();
90 IsGCActiveMark mark;
91
92 if (ScavengeBeforeFullGC) {
93 PSScavenge::invoke_no_policy();
94 }
95
96 const bool clear_all_soft_refs =
97 heap->collector_policy()->should_clear_all_soft_refs();
98
99 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
100 UIntXFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
101 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
102 }
103
104 // This method contains no policy. You should probably
105 // be calling invoke() instead.
106 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
107 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
108 assert(ref_processor() != NULL, "Sanity");
109
110 if (GC_locker::check_active_before_gc()) {
111 return false;
112 }
113
114 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
115 GCCause::Cause gc_cause = heap->gc_cause();
116
117 GCIdMark gc_id_mark;
118 _gc_timer->register_gc_start();
119 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
120
121 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
122
123 // The scope of casr should end after code that can change
124 // CollectorPolicy::_should_clear_all_soft_refs.
125 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
126
127 PSYoungGen* young_gen = heap->young_gen();
128 PSOldGen* old_gen = heap->old_gen();
129
130 // Increment the invocation count
131 heap->increment_total_collections(true /* full */);
132
133 // Save information needed to minimize mangling
134 heap->record_gen_tops_before_GC();
135
136 // We need to track unique mark sweep invocations as well.
137 _total_invocations++;
138
139 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
140
141 heap->print_heap_before_gc();
142 heap->trace_heap_before_gc(_gc_tracer);
143
144 // Fill in TLABs
145 heap->accumulate_statistics_all_tlabs();
146 heap->ensure_parsability(true); // retire TLABs
147
148 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
149 HandleMark hm; // Discard invalid handles created during verification
150 Universe::verify(" VerifyBeforeGC:");
151 }
152
153 // Verify object start arrays
154 if (VerifyObjectStartArray &&
155 VerifyBeforeGC) {
156 old_gen->verify_object_start_array();
157 }
158
159 heap->pre_full_gc_dump(_gc_timer);
160
161 // Filled in below to track the state of the young gen after the collection.
162 bool eden_empty;
163 bool survivors_empty;
164 bool young_gen_empty;
165
166 {
167 HandleMark hm;
168
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 (TraceOldGenTime) 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 BiasedLocking::preserve_marks();
181
182 // Capture heap size before collection for printing.
183 size_t prev_used = heap->used();
184
185 // Capture metadata size before collection for sizing.
186 size_t metadata_prev_used = MetaspaceAux::used_bytes();
187
188 // For PrintGCDetails
189 size_t old_gen_prev_used = old_gen->used_in_bytes();
190 size_t young_gen_prev_used = young_gen->used_in_bytes();
191
192 allocate_stacks();
193
194 #if defined(COMPILER2) || INCLUDE_JVMCI
195 DerivedPointerTable::clear();
196 #endif
197
198 ref_processor()->enable_discovery();
199 ref_processor()->setup_policy(clear_all_softrefs);
200
201 mark_sweep_phase1(clear_all_softrefs);
202
203 mark_sweep_phase2();
204
205 #if defined(COMPILER2) || INCLUDE_JVMCI
206 // Don't add any more derived pointers during phase3
207 assert(DerivedPointerTable::is_active(), "Sanity");
208 DerivedPointerTable::set_active(false);
209 #endif
210
211 mark_sweep_phase3();
212
213 mark_sweep_phase4();
214
215 restore_marks();
216
217 deallocate_stacks();
218
219 if (ZapUnusedHeapArea) {
220 // Do a complete mangle (top to end) because the usage for
221 // scratch does not maintain a top pointer.
222 young_gen->to_space()->mangle_unused_area_complete();
223 }
224
225 eden_empty = young_gen->eden_space()->is_empty();
226 if (!eden_empty) {
227 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
228 }
229
230 // Update heap occupancy information which is used as
231 // input to soft ref clearing policy at the next gc.
232 Universe::update_heap_info_at_gc();
233
234 survivors_empty = young_gen->from_space()->is_empty() &&
235 young_gen->to_space()->is_empty();
236 young_gen_empty = eden_empty && survivors_empty;
237
238 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
239 MemRegion old_mr = heap->old_gen()->reserved();
240 if (young_gen_empty) {
241 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
242 } else {
243 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
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 CodeCache::gc_epilogue();
252 JvmtiExport::gc_epilogue();
253
254 #if defined(COMPILER2) || INCLUDE_JVMCI
255 DerivedPointerTable::update_pointers();
256 #endif
257
258 ref_processor()->enqueue_discovered_references(NULL);
259
260 // Update time of last GC
261 reset_millis_since_last_gc();
262
263 // Let the size policy know we're done
264 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
265
266 if (UseAdaptiveSizePolicy) {
267
268 if (PrintAdaptiveSizePolicy) {
269 gclog_or_tty->print("AdaptiveSizeStart: ");
270 gclog_or_tty->stamp();
271 gclog_or_tty->print_cr(" collection: %d ",
272 heap->total_collections());
273 if (Verbose) {
274 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
275 " young_gen_capacity: " SIZE_FORMAT,
276 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
277 }
278 }
279
280 // Don't check if the size_policy is ready here. Let
281 // the size_policy check that internally.
282 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
283 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
284 // Swap the survivor spaces if from_space is empty. The
285 // resize_young_gen() called below is normally used after
286 // a successful young GC and swapping of survivor spaces;
287 // otherwise, it will fail to resize the young gen with
288 // the current implementation.
289 if (young_gen->from_space()->is_empty()) {
290 young_gen->from_space()->clear(SpaceDecorator::Mangle);
291 young_gen->swap_spaces();
292 }
293
294 // Calculate optimal free space amounts
295 assert(young_gen->max_size() >
296 young_gen->from_space()->capacity_in_bytes() +
297 young_gen->to_space()->capacity_in_bytes(),
298 "Sizes of space in young gen are out-of-bounds");
299
300 size_t young_live = young_gen->used_in_bytes();
301 size_t eden_live = young_gen->eden_space()->used_in_bytes();
302 size_t old_live = old_gen->used_in_bytes();
303 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
304 size_t max_old_gen_size = old_gen->max_gen_size();
305 size_t max_eden_size = young_gen->max_size() -
306 young_gen->from_space()->capacity_in_bytes() -
307 young_gen->to_space()->capacity_in_bytes();
308
309 // Used for diagnostics
310 size_policy->clear_generation_free_space_flags();
311
312 size_policy->compute_generations_free_space(young_live,
313 eden_live,
314 old_live,
315 cur_eden,
316 max_old_gen_size,
317 max_eden_size,
318 true /* full gc*/);
319
320 size_policy->check_gc_overhead_limit(young_live,
321 eden_live,
322 max_old_gen_size,
323 max_eden_size,
324 true /* full gc*/,
325 gc_cause,
326 heap->collector_policy());
327
328 size_policy->decay_supplemental_growth(true /* full gc*/);
329
330 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
331
332 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
333 size_policy->calculated_survivor_size_in_bytes());
334 }
335 if (PrintAdaptiveSizePolicy) {
336 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
337 heap->total_collections());
338 }
339 }
340
341 if (UsePerfData) {
342 heap->gc_policy_counters()->update_counters();
343 heap->gc_policy_counters()->update_old_capacity(
344 old_gen->capacity_in_bytes());
345 heap->gc_policy_counters()->update_young_capacity(
346 young_gen->capacity_in_bytes());
347 }
348
349 heap->resize_all_tlabs();
350
351 // We collected the heap, recalculate the metaspace capacity
352 MetaspaceGC::compute_new_size();
353
354 if (TraceOldGenTime) accumulated_time()->stop();
355
356 if (PrintGC) {
357 if (PrintGCDetails) {
358 // Don't print a GC timestamp here. This is after the GC so
359 // would be confusing.
360 young_gen->print_used_change(young_gen_prev_used);
361 old_gen->print_used_change(old_gen_prev_used);
362 }
363 heap->print_heap_change(prev_used);
364 if (PrintGCDetails) {
365 MetaspaceAux::print_metaspace_change(metadata_prev_used);
366 }
367 }
368
369 // Track memory usage and detect low memory
370 MemoryService::track_memory_usage();
371 heap->update_counters();
372 }
373
374 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
375 HandleMark hm; // Discard invalid handles created during verification
376 Universe::verify(" VerifyAfterGC:");
377 }
378
379 // Re-verify object start arrays
380 if (VerifyObjectStartArray &&
381 VerifyAfterGC) {
382 old_gen->verify_object_start_array();
383 }
384
385 if (ZapUnusedHeapArea) {
386 old_gen->object_space()->check_mangled_unused_area_complete();
387 }
388
389 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
390
391 heap->print_heap_after_gc();
392 heap->trace_heap_after_gc(_gc_tracer);
393
394 heap->post_full_gc_dump(_gc_timer);
395
396 #ifdef TRACESPINNING
397 ParallelTaskTerminator::print_termination_counts();
398 #endif
399
400 _gc_timer->register_gc_end();
401
402 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
403
404 return true;
405 }
406
407 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
408 PSYoungGen* young_gen,
409 PSOldGen* old_gen) {
410 MutableSpace* const eden_space = young_gen->eden_space();
411 assert(!eden_space->is_empty(), "eden must be non-empty");
412 assert(young_gen->virtual_space()->alignment() ==
413 old_gen->virtual_space()->alignment(), "alignments do not match");
414
415 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
416 return false;
417 }
418
419 // Both generations must be completely committed.
420 if (young_gen->virtual_space()->uncommitted_size() != 0) {
421 return false;
422 }
423 if (old_gen->virtual_space()->uncommitted_size() != 0) {
424 return false;
425 }
426
427 // Figure out how much to take from eden. Include the average amount promoted
428 // in the total; otherwise the next young gen GC will simply bail out to a
429 // full GC.
430 const size_t alignment = old_gen->virtual_space()->alignment();
431 const size_t eden_used = eden_space->used_in_bytes();
432 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
433 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
434 const size_t eden_capacity = eden_space->capacity_in_bytes();
435
436 if (absorb_size >= eden_capacity) {
437 return false; // Must leave some space in eden.
438 }
439
440 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
441 if (new_young_size < young_gen->min_gen_size()) {
442 return false; // Respect young gen minimum size.
443 }
444
445 if (TraceAdaptiveGCBoundary && Verbose) {
446 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
447 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
448 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
449 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
450 absorb_size / K,
451 eden_capacity / K, (eden_capacity - absorb_size) / K,
452 young_gen->from_space()->used_in_bytes() / K,
453 young_gen->to_space()->used_in_bytes() / K,
454 young_gen->capacity_in_bytes() / K, new_young_size / K);
455 }
456
457 // Fill the unused part of the old gen.
458 MutableSpace* const old_space = old_gen->object_space();
459 HeapWord* const unused_start = old_space->top();
460 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
461
462 if (unused_words > 0) {
463 if (unused_words < CollectedHeap::min_fill_size()) {
464 return false; // If the old gen cannot be filled, must give up.
465 }
466 CollectedHeap::fill_with_objects(unused_start, unused_words);
467 }
468
469 // Take the live data from eden and set both top and end in the old gen to
470 // eden top. (Need to set end because reset_after_change() mangles the region
471 // from end to virtual_space->high() in debug builds).
472 HeapWord* const new_top = eden_space->top();
473 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
474 absorb_size);
475 young_gen->reset_after_change();
476 old_space->set_top(new_top);
477 old_space->set_end(new_top);
478 old_gen->reset_after_change();
479
480 // Update the object start array for the filler object and the data from eden.
481 ObjectStartArray* const start_array = old_gen->start_array();
482 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
483 start_array->allocate_block(p);
484 }
485
486 // Could update the promoted average here, but it is not typically updated at
487 // full GCs and the value to use is unclear. Something like
488 //
489 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
490
491 size_policy->set_bytes_absorbed_from_eden(absorb_size);
492 return true;
493 }
494
495 void PSMarkSweep::allocate_stacks() {
496 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
497 PSYoungGen* young_gen = heap->young_gen();
498
499 MutableSpace* to_space = young_gen->to_space();
500 _preserved_marks = (PreservedMark*)to_space->top();
501 _preserved_count = 0;
502
503 // We want to calculate the size in bytes first.
504 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
505 // Now divide by the size of a PreservedMark
506 _preserved_count_max /= sizeof(PreservedMark);
507 }
508
509
510 void PSMarkSweep::deallocate_stacks() {
511 _preserved_mark_stack.clear(true);
512 _preserved_oop_stack.clear(true);
513 _marking_stack.clear();
514 _objarray_stack.clear(true);
515 }
516
517 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
518 // Recursively traverse all live objects and mark them
519 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer);
520
521 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
522
523 // Need to clear claim bits before the tracing starts.
524 ClassLoaderDataGraph::clear_claimed_marks();
525
526 // General strong roots.
527 {
528 ParallelScavengeHeap::ParStrongRootsScope psrs;
529 Universe::oops_do(mark_and_push_closure());
530 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
531 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
532 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
533 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
534 ObjectSynchronizer::oops_do(mark_and_push_closure());
535 FlatProfiler::oops_do(mark_and_push_closure());
536 Management::oops_do(mark_and_push_closure());
537 JvmtiExport::oops_do(mark_and_push_closure());
538 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
539 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
540 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
541 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
542 }
543
544 // Flush marking stack.
545 follow_stack();
546
547 // Process reference objects found during marking
548 {
549 ref_processor()->setup_policy(clear_all_softrefs);
550 const ReferenceProcessorStats& stats =
551 ref_processor()->process_discovered_references(
552 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer);
553 gc_tracer()->report_gc_reference_stats(stats);
554 }
555
556 // This is the point where the entire marking should have completed.
557 assert(_marking_stack.is_empty(), "Marking should have completed");
558
559 // Unload classes and purge the SystemDictionary.
560 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
561
562 // Unload nmethods.
563 CodeCache::do_unloading(is_alive_closure(), purged_class);
564
565 // Prune dead klasses from subklass/sibling/implementor lists.
566 Klass::clean_weak_klass_links(is_alive_closure());
567
568 // Delete entries for dead interned strings.
569 StringTable::unlink(is_alive_closure());
570
571 // Clean up unreferenced symbols in symbol table.
572 SymbolTable::unlink();
573 _gc_tracer->report_object_count_after_gc(is_alive_closure());
574 }
575
576
577 void PSMarkSweep::mark_sweep_phase2() {
578 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer);
579
580 // Now all live objects are marked, compute the new object addresses.
581
582 // It is not required that we traverse spaces in the same order in
583 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
584 // tracking expects us to do so. See comment under phase4.
585
586 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
587 PSOldGen* old_gen = heap->old_gen();
588
589 // Begin compacting into the old gen
590 PSMarkSweepDecorator::set_destination_decorator_tenured();
591
592 // This will also compact the young gen spaces.
593 old_gen->precompact();
594 }
595
596 // This should be moved to the shared markSweep code!
597 class PSAlwaysTrueClosure: public BoolObjectClosure {
598 public:
599 bool do_object_b(oop p) { return true; }
600 };
601 static PSAlwaysTrueClosure always_true;
602
603 void PSMarkSweep::mark_sweep_phase3() {
604 // Adjust the pointers to reflect the new locations
605 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer);
606
607 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
608 PSYoungGen* young_gen = heap->young_gen();
609 PSOldGen* old_gen = heap->old_gen();
610
611 // Need to clear claim bits before the tracing starts.
612 ClassLoaderDataGraph::clear_claimed_marks();
613
614 // General strong roots.
615 Universe::oops_do(adjust_pointer_closure());
616 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
617 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
618 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
619 ObjectSynchronizer::oops_do(adjust_pointer_closure());
620 FlatProfiler::oops_do(adjust_pointer_closure());
621 Management::oops_do(adjust_pointer_closure());
622 JvmtiExport::oops_do(adjust_pointer_closure());
623 SystemDictionary::oops_do(adjust_pointer_closure());
624 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
625
626 // Now adjust pointers in remaining weak roots. (All of which should
627 // have been cleared if they pointed to non-surviving objects.)
628 // Global (weak) JNI handles
629 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
630
631 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
632 CodeCache::blobs_do(&adjust_from_blobs);
633 StringTable::oops_do(adjust_pointer_closure());
634 ref_processor()->weak_oops_do(adjust_pointer_closure());
635 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
636
637 adjust_marks();
638
639 young_gen->adjust_pointers();
640 old_gen->adjust_pointers();
641 }
642
643 void PSMarkSweep::mark_sweep_phase4() {
644 EventMark m("4 compact heap");
645 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer);
646
647 // All pointers are now adjusted, move objects accordingly
648
649 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
650 PSYoungGen* young_gen = heap->young_gen();
651 PSOldGen* old_gen = heap->old_gen();
652
653 old_gen->compact();
654 young_gen->compact();
655 }
656
657 jlong PSMarkSweep::millis_since_last_gc() {
658 // We need a monotonically non-decreasing time in ms but
659 // os::javaTimeMillis() does not guarantee monotonicity.
660 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
661 jlong ret_val = now - _time_of_last_gc;
662 // XXX See note in genCollectedHeap::millis_since_last_gc().
663 if (ret_val < 0) {
664 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
665 return 0;
666 }
667 return ret_val;
668 }
669
670 void PSMarkSweep::reset_millis_since_last_gc() {
671 // We need a monotonically non-decreasing time in ms but
672 // os::javaTimeMillis() does not guarantee monotonicity.
673 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
674 }