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 "logging/log.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "runtime/biasedLocking.hpp"
51 #include "runtime/fprofiler.hpp"
52 #include "runtime/safepoint.hpp"
53 #include "runtime/vmThread.hpp"
54 #include "services/management.hpp"
55 #include "services/memoryService.hpp"
56 #include "utilities/events.hpp"
57 #include "utilities/stack.inline.hpp"
58
59 elapsedTimer PSMarkSweep::_accumulated_time;
60 jlong PSMarkSweep::_time_of_last_gc = 0;
61 CollectorCounters* PSMarkSweep::_counters = NULL;
62
63 void PSMarkSweep::initialize() {
64 MemRegion mr = ParallelScavengeHeap::heap()->reserved_region();
65 set_ref_processor(new ReferenceProcessor(mr)); // a vanilla ref proc
66 _counters = new CollectorCounters("PSMarkSweep", 1);
67 }
68
69 // This method contains all heap specific policy for invoking mark sweep.
70 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
71 // the heap. It will do nothing further. If we need to bail out for policy
72 // reasons, scavenge before full gc, or any other specialized behavior, it
73 // needs to be added here.
74 //
75 // Note that this method should only be called from the vm_thread while
76 // at a safepoint!
77 //
78 // Note that the all_soft_refs_clear flag in the collector policy
79 // may be true because this method can be called without intervening
80 // activity. For example when the heap space is tight and full measure
81 // are being taken to free space.
82
83 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
84 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
85 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
86 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant");
87
88 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
89 GCCause::Cause gc_cause = heap->gc_cause();
90 PSAdaptiveSizePolicy* policy = heap->size_policy();
91 IsGCActiveMark mark;
92
93 if (ScavengeBeforeFullGC) {
94 PSScavenge::invoke_no_policy();
95 }
96
97 const bool clear_all_soft_refs =
98 heap->collector_policy()->should_clear_all_soft_refs();
99
100 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
101 UIntXFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
102 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
103 }
104
105 // This method contains no policy. You should probably
106 // be calling invoke() instead.
107 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
108 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
109 assert(ref_processor() != NULL, "Sanity");
110
111 if (GC_locker::check_active_before_gc()) {
112 return false;
113 }
114
115 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
116 GCCause::Cause gc_cause = heap->gc_cause();
117
118 GCIdMark gc_id_mark;
119 _gc_timer->register_gc_start();
120 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
121
122 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
123
124 // The scope of casr should end after code that can change
125 // CollectorPolicy::_should_clear_all_soft_refs.
126 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
127
128 PSYoungGen* young_gen = heap->young_gen();
129 PSOldGen* old_gen = heap->old_gen();
130
131 // Increment the invocation count
132 heap->increment_total_collections(true /* full */);
133
134 // Save information needed to minimize mangling
135 heap->record_gen_tops_before_GC();
136
137 // We need to track unique mark sweep invocations as well.
138 _total_invocations++;
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("Before GC");
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 GCTraceCPUTime tcpu;
169 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause, true);
170 TraceCollectorStats tcs(counters());
171 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
172
173 if (TraceOldGenTime) accumulated_time()->start();
174
175 // Let the size policy know we're starting
176 size_policy->major_collection_begin();
177
178 CodeCache::gc_prologue();
179 BiasedLocking::preserve_marks();
180
181 // Capture metadata size before collection for sizing.
182 size_t metadata_prev_used = MetaspaceAux::used_bytes();
183
184 // For PrintGCDetails
185 size_t old_gen_prev_used = old_gen->used_in_bytes();
186 size_t young_gen_prev_used = young_gen->used_in_bytes();
187
188 allocate_stacks();
189
190 #if defined(COMPILER2) || INCLUDE_JVMCI
191 DerivedPointerTable::clear();
192 #endif
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 #if defined(COMPILER2) || INCLUDE_JVMCI
202 // Don't add any more derived pointers during phase3
203 assert(DerivedPointerTable::is_active(), "Sanity");
204 DerivedPointerTable::set_active(false);
205 #endif
206
207 mark_sweep_phase3();
208
209 mark_sweep_phase4();
210
211 restore_marks();
212
213 deallocate_stacks();
214
215 if (ZapUnusedHeapArea) {
216 // Do a complete mangle (top to end) because the usage for
217 // scratch does not maintain a top pointer.
218 young_gen->to_space()->mangle_unused_area_complete();
219 }
220
221 eden_empty = young_gen->eden_space()->is_empty();
222 if (!eden_empty) {
223 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
224 }
225
226 // Update heap occupancy information which is used as
227 // input to soft ref clearing policy at the next gc.
228 Universe::update_heap_info_at_gc();
229
230 survivors_empty = young_gen->from_space()->is_empty() &&
231 young_gen->to_space()->is_empty();
232 young_gen_empty = eden_empty && survivors_empty;
233
234 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
235 MemRegion old_mr = heap->old_gen()->reserved();
236 if (young_gen_empty) {
237 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
238 } else {
239 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
240 }
241
242 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
243 ClassLoaderDataGraph::purge();
244 MetaspaceAux::verify_metrics();
245
246 BiasedLocking::restore_marks();
247 CodeCache::gc_epilogue();
248 JvmtiExport::gc_epilogue();
249
250 #if defined(COMPILER2) || INCLUDE_JVMCI
251 DerivedPointerTable::update_pointers();
252 #endif
253
254 ref_processor()->enqueue_discovered_references(NULL);
255
256 // Update time of last GC
257 reset_millis_since_last_gc();
258
259 // Let the size policy know we're done
260 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
261
262 if (UseAdaptiveSizePolicy) {
263
264 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
265 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
266 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
267
268 // Don't check if the size_policy is ready here. Let
269 // the size_policy check that internally.
270 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
271 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
272 // Swap the survivor spaces if from_space is empty. The
273 // resize_young_gen() called below is normally used after
274 // a successful young GC and swapping of survivor spaces;
275 // otherwise, it will fail to resize the young gen with
276 // the current implementation.
277 if (young_gen->from_space()->is_empty()) {
278 young_gen->from_space()->clear(SpaceDecorator::Mangle);
279 young_gen->swap_spaces();
280 }
281
282 // Calculate optimal free space amounts
283 assert(young_gen->max_size() >
284 young_gen->from_space()->capacity_in_bytes() +
285 young_gen->to_space()->capacity_in_bytes(),
286 "Sizes of space in young gen are out-of-bounds");
287
288 size_t young_live = young_gen->used_in_bytes();
289 size_t eden_live = young_gen->eden_space()->used_in_bytes();
290 size_t old_live = old_gen->used_in_bytes();
291 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
292 size_t max_old_gen_size = old_gen->max_gen_size();
293 size_t max_eden_size = young_gen->max_size() -
294 young_gen->from_space()->capacity_in_bytes() -
295 young_gen->to_space()->capacity_in_bytes();
296
297 // Used for diagnostics
298 size_policy->clear_generation_free_space_flags();
299
300 size_policy->compute_generations_free_space(young_live,
301 eden_live,
302 old_live,
303 cur_eden,
304 max_old_gen_size,
305 max_eden_size,
306 true /* full gc*/);
307
308 size_policy->check_gc_overhead_limit(young_live,
309 eden_live,
310 max_old_gen_size,
311 max_eden_size,
312 true /* full gc*/,
313 gc_cause,
314 heap->collector_policy());
315
316 size_policy->decay_supplemental_growth(true /* full gc*/);
317
318 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
319
320 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
321 size_policy->calculated_survivor_size_in_bytes());
322 }
323 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
324 }
325
326 if (UsePerfData) {
327 heap->gc_policy_counters()->update_counters();
328 heap->gc_policy_counters()->update_old_capacity(
329 old_gen->capacity_in_bytes());
330 heap->gc_policy_counters()->update_young_capacity(
331 young_gen->capacity_in_bytes());
332 }
333
334 heap->resize_all_tlabs();
335
336 // We collected the heap, recalculate the metaspace capacity
337 MetaspaceGC::compute_new_size();
338
339 if (TraceOldGenTime) accumulated_time()->stop();
340
341 if (PrintGC) {
342 if (PrintGCDetails) {
343 // Don't print a GC timestamp here. This is after the GC so
344 // would be confusing.
345 young_gen->print_used_change(young_gen_prev_used);
346 old_gen->print_used_change(old_gen_prev_used);
347 }
348 if (PrintGCDetails) {
349 MetaspaceAux::print_metaspace_change(metadata_prev_used);
350 }
351 }
352
353 // Track memory usage and detect low memory
354 MemoryService::track_memory_usage();
355 heap->update_counters();
356 }
357
358 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
359 HandleMark hm; // Discard invalid handles created during verification
360 Universe::verify("After GC");
361 }
362
363 // Re-verify object start arrays
364 if (VerifyObjectStartArray &&
365 VerifyAfterGC) {
366 old_gen->verify_object_start_array();
367 }
368
369 if (ZapUnusedHeapArea) {
370 old_gen->object_space()->check_mangled_unused_area_complete();
371 }
372
373 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
374
375 heap->print_heap_after_gc();
376 heap->trace_heap_after_gc(_gc_tracer);
377
378 heap->post_full_gc_dump(_gc_timer);
379
380 #ifdef TRACESPINNING
381 ParallelTaskTerminator::print_termination_counts();
382 #endif
383
384 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
385
386 _gc_timer->register_gc_end();
387
388 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
389
390 return true;
391 }
392
393 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
394 PSYoungGen* young_gen,
395 PSOldGen* old_gen) {
396 MutableSpace* const eden_space = young_gen->eden_space();
397 assert(!eden_space->is_empty(), "eden must be non-empty");
398 assert(young_gen->virtual_space()->alignment() ==
399 old_gen->virtual_space()->alignment(), "alignments do not match");
400
401 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
402 return false;
403 }
404
405 // Both generations must be completely committed.
406 if (young_gen->virtual_space()->uncommitted_size() != 0) {
407 return false;
408 }
409 if (old_gen->virtual_space()->uncommitted_size() != 0) {
410 return false;
411 }
412
413 // Figure out how much to take from eden. Include the average amount promoted
414 // in the total; otherwise the next young gen GC will simply bail out to a
415 // full GC.
416 const size_t alignment = old_gen->virtual_space()->alignment();
417 const size_t eden_used = eden_space->used_in_bytes();
418 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
419 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
420 const size_t eden_capacity = eden_space->capacity_in_bytes();
421
422 if (absorb_size >= eden_capacity) {
423 return false; // Must leave some space in eden.
424 }
425
426 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
427 if (new_young_size < young_gen->min_gen_size()) {
428 return false; // Respect young gen minimum size.
429 }
430
431 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: "
432 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
433 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
434 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
435 absorb_size / K,
436 eden_capacity / K, (eden_capacity - absorb_size) / K,
437 young_gen->from_space()->used_in_bytes() / K,
438 young_gen->to_space()->used_in_bytes() / K,
439 young_gen->capacity_in_bytes() / K, new_young_size / K);
440
441 // Fill the unused part of the old gen.
442 MutableSpace* const old_space = old_gen->object_space();
443 HeapWord* const unused_start = old_space->top();
444 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
445
446 if (unused_words > 0) {
447 if (unused_words < CollectedHeap::min_fill_size()) {
448 return false; // If the old gen cannot be filled, must give up.
449 }
450 CollectedHeap::fill_with_objects(unused_start, unused_words);
451 }
452
453 // Take the live data from eden and set both top and end in the old gen to
454 // eden top. (Need to set end because reset_after_change() mangles the region
455 // from end to virtual_space->high() in debug builds).
456 HeapWord* const new_top = eden_space->top();
457 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
458 absorb_size);
459 young_gen->reset_after_change();
460 old_space->set_top(new_top);
461 old_space->set_end(new_top);
462 old_gen->reset_after_change();
463
464 // Update the object start array for the filler object and the data from eden.
465 ObjectStartArray* const start_array = old_gen->start_array();
466 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
467 start_array->allocate_block(p);
468 }
469
470 // Could update the promoted average here, but it is not typically updated at
471 // full GCs and the value to use is unclear. Something like
472 //
473 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
474
475 size_policy->set_bytes_absorbed_from_eden(absorb_size);
476 return true;
477 }
478
479 void PSMarkSweep::allocate_stacks() {
480 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
481 PSYoungGen* young_gen = heap->young_gen();
482
483 MutableSpace* to_space = young_gen->to_space();
484 _preserved_marks = (PreservedMark*)to_space->top();
485 _preserved_count = 0;
486
487 // We want to calculate the size in bytes first.
488 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
489 // Now divide by the size of a PreservedMark
490 _preserved_count_max /= sizeof(PreservedMark);
491 }
492
493
494 void PSMarkSweep::deallocate_stacks() {
495 _preserved_mark_stack.clear(true);
496 _preserved_oop_stack.clear(true);
497 _marking_stack.clear();
498 _objarray_stack.clear(true);
499 }
500
501 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
502 // Recursively traverse all live objects and mark them
503 GCTraceTime(Trace, gc) tm("phase 1: Mark live objects", _gc_timer);
504
505 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
506
507 // Need to clear claim bits before the tracing starts.
508 ClassLoaderDataGraph::clear_claimed_marks();
509
510 // General strong roots.
511 {
512 ParallelScavengeHeap::ParStrongRootsScope psrs;
513 Universe::oops_do(mark_and_push_closure());
514 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
515 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
516 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
517 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
518 ObjectSynchronizer::oops_do(mark_and_push_closure());
519 FlatProfiler::oops_do(mark_and_push_closure());
520 Management::oops_do(mark_and_push_closure());
521 JvmtiExport::oops_do(mark_and_push_closure());
522 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
523 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
524 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
525 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
526 }
527
528 // Flush marking stack.
529 follow_stack();
530
531 // Process reference objects found during marking
532 {
533 ref_processor()->setup_policy(clear_all_softrefs);
534 const ReferenceProcessorStats& stats =
535 ref_processor()->process_discovered_references(
536 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer);
537 gc_tracer()->report_gc_reference_stats(stats);
538 }
539
540 // This is the point where the entire marking should have completed.
541 assert(_marking_stack.is_empty(), "Marking should have completed");
542
543 // Unload classes and purge the SystemDictionary.
544 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
545
546 // Unload nmethods.
547 CodeCache::do_unloading(is_alive_closure(), purged_class);
548
549 // Prune dead klasses from subklass/sibling/implementor lists.
550 Klass::clean_weak_klass_links(is_alive_closure());
551
552 // Delete entries for dead interned strings.
553 StringTable::unlink(is_alive_closure());
554
555 // Clean up unreferenced symbols in symbol table.
556 SymbolTable::unlink();
557 _gc_tracer->report_object_count_after_gc(is_alive_closure());
558 }
559
560
561 void PSMarkSweep::mark_sweep_phase2() {
562 GCTraceTime(Trace, gc) tm("phase 2: Compute new object addresses", _gc_timer);
563
564 // Now all live objects are marked, compute the new object addresses.
565
566 // It is not required that we traverse spaces in the same order in
567 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
568 // tracking expects us to do so. See comment under phase4.
569
570 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
571 PSOldGen* old_gen = heap->old_gen();
572
573 // Begin compacting into the old gen
574 PSMarkSweepDecorator::set_destination_decorator_tenured();
575
576 // This will also compact the young gen spaces.
577 old_gen->precompact();
578 }
579
580 // This should be moved to the shared markSweep code!
581 class PSAlwaysTrueClosure: public BoolObjectClosure {
582 public:
583 bool do_object_b(oop p) { return true; }
584 };
585 static PSAlwaysTrueClosure always_true;
586
587 void PSMarkSweep::mark_sweep_phase3() {
588 // Adjust the pointers to reflect the new locations
589 GCTraceTime(Trace, gc) tm("phase 3: Adjust pointers", _gc_timer);
590
591 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
592 PSYoungGen* young_gen = heap->young_gen();
593 PSOldGen* old_gen = heap->old_gen();
594
595 // Need to clear claim bits before the tracing starts.
596 ClassLoaderDataGraph::clear_claimed_marks();
597
598 // General strong roots.
599 Universe::oops_do(adjust_pointer_closure());
600 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
601 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
602 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
603 ObjectSynchronizer::oops_do(adjust_pointer_closure());
604 FlatProfiler::oops_do(adjust_pointer_closure());
605 Management::oops_do(adjust_pointer_closure());
606 JvmtiExport::oops_do(adjust_pointer_closure());
607 SystemDictionary::oops_do(adjust_pointer_closure());
608 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
609
610 // Now adjust pointers in remaining weak roots. (All of which should
611 // have been cleared if they pointed to non-surviving objects.)
612 // Global (weak) JNI handles
613 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
614
615 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
616 CodeCache::blobs_do(&adjust_from_blobs);
617 StringTable::oops_do(adjust_pointer_closure());
618 ref_processor()->weak_oops_do(adjust_pointer_closure());
619 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
620
621 adjust_marks();
622
623 young_gen->adjust_pointers();
624 old_gen->adjust_pointers();
625 }
626
627 void PSMarkSweep::mark_sweep_phase4() {
628 EventMark m("4 compact heap");
629 GCTraceTime(Trace, gc) tm("phase 4: Move objects", _gc_timer);
630
631 // All pointers are now adjusted, move objects accordingly
632
633 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
634 PSYoungGen* young_gen = heap->young_gen();
635 PSOldGen* old_gen = heap->old_gen();
636
637 old_gen->compact();
638 young_gen->compact();
639 }
640
641 jlong PSMarkSweep::millis_since_last_gc() {
642 // We need a monotonically non-decreasing time in ms but
643 // os::javaTimeMillis() does not guarantee monotonicity.
644 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
645 jlong ret_val = now - _time_of_last_gc;
646 // XXX See note in genCollectedHeap::millis_since_last_gc().
647 if (ret_val < 0) {
648 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
649 return 0;
650 }
651 return ret_val;
652 }
653
654 void PSMarkSweep::reset_millis_since_last_gc() {
655 // We need a monotonically non-decreasing time in ms but
656 // os::javaTimeMillis() does not guarantee monotonicity.
657 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
658 }