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 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
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 = Universe::heap()->reserved_region();
65 _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(!Universe::heap()->is_gc_active(), "not reentrant");
87
88 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::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 UIntFlagSetting 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*)Universe::heap();
116 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
117 GCCause::Cause gc_cause = heap->gc_cause();
118
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 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
141
142 heap->print_heap_before_gc();
143 heap->trace_heap_before_gc(_gc_tracer);
144
145 // Fill in TLABs
146 heap->accumulate_statistics_all_tlabs();
147 heap->ensure_parsability(true); // retire TLABs
148
149 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
150 HandleMark hm; // Discard invalid handles created during verification
151 Universe::verify(" VerifyBeforeGC:");
152 }
153
154 // Verify object start arrays
155 if (VerifyObjectStartArray &&
156 VerifyBeforeGC) {
157 old_gen->verify_object_start_array();
158 }
159
160 heap->pre_full_gc_dump(_gc_timer);
161
162 // Filled in below to track the state of the young gen after the collection.
163 bool eden_empty;
164 bool survivors_empty;
165 bool young_gen_empty;
166
167 {
168 HandleMark hm;
169
170 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
171 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer->gc_id());
172 TraceCollectorStats tcs(counters());
173 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
174
175 if (TraceOldGenTime) accumulated_time()->start();
176
177 // Let the size policy know we're starting
178 size_policy->major_collection_begin();
179
180 CodeCache::gc_prologue();
181 BiasedLocking::preserve_marks();
182
183 // Capture heap size before collection for printing.
184 size_t prev_used = heap->used();
185
186 // Capture metadata size before collection for sizing.
187 size_t metadata_prev_used = MetaspaceAux::used_bytes();
188
189 // For PrintGCDetails
190 size_t old_gen_prev_used = old_gen->used_in_bytes();
191 size_t young_gen_prev_used = young_gen->used_in_bytes();
192
193 allocate_stacks();
194
195 COMPILER2_PRESENT(DerivedPointerTable::clear());
196
197 ref_processor()->enable_discovery();
198 ref_processor()->setup_policy(clear_all_softrefs);
199
200 mark_sweep_phase1(clear_all_softrefs);
201
202 mark_sweep_phase2();
203
204 // Don't add any more derived pointers during phase3
205 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
206 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
207
208 mark_sweep_phase3();
209
210 mark_sweep_phase4();
211
212 restore_marks();
213
214 deallocate_stacks();
215
216 if (ZapUnusedHeapArea) {
217 // Do a complete mangle (top to end) because the usage for
218 // scratch does not maintain a top pointer.
219 young_gen->to_space()->mangle_unused_area_complete();
220 }
221
222 eden_empty = young_gen->eden_space()->is_empty();
223 if (!eden_empty) {
224 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
225 }
226
227 // Update heap occupancy information which is used as
228 // input to soft ref clearing policy at the next gc.
229 Universe::update_heap_info_at_gc();
230
231 survivors_empty = young_gen->from_space()->is_empty() &&
232 young_gen->to_space()->is_empty();
233 young_gen_empty = eden_empty && survivors_empty;
234
235 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
236 MemRegion old_mr = heap->old_gen()->reserved();
237 if (young_gen_empty) {
238 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
239 } else {
240 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
241 }
242
243 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
244 ClassLoaderDataGraph::purge();
245 MetaspaceAux::verify_metrics();
246
247 BiasedLocking::restore_marks();
248 CodeCache::gc_epilogue();
249 JvmtiExport::gc_epilogue();
250
251 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
252
253 ref_processor()->enqueue_discovered_references(NULL);
254
255 // Update time of last GC
256 reset_millis_since_last_gc();
257
258 // Let the size policy know we're done
259 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
260
261 if (UseAdaptiveSizePolicy) {
262
263 if (PrintAdaptiveSizePolicy) {
264 gclog_or_tty->print("AdaptiveSizeStart: ");
265 gclog_or_tty->stamp();
266 gclog_or_tty->print_cr(" collection: %d ",
267 heap->total_collections());
268 if (Verbose) {
269 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
270 " young_gen_capacity: " SIZE_FORMAT,
271 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
272 }
273 }
274
275 // Don't check if the size_policy is ready here. Let
276 // the size_policy check that internally.
277 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
278 (!GCCause::is_user_requested_gc(gc_cause) ||
279 UseAdaptiveSizePolicyWithSystemGC)) {
280 // Swap the survivor spaces if from_space is empty. The
281 // resize_young_gen() called below is normally used after
282 // a successful young GC and swapping of survivor spaces;
283 // otherwise, it will fail to resize the young gen with
284 // the current implementation.
285 if (young_gen->from_space()->is_empty()) {
286 young_gen->from_space()->clear(SpaceDecorator::Mangle);
287 young_gen->swap_spaces();
288 }
289
290 // Calculate optimal free space amounts
291 assert(young_gen->max_size() >
292 young_gen->from_space()->capacity_in_bytes() +
293 young_gen->to_space()->capacity_in_bytes(),
294 "Sizes of space in young gen are out-of-bounds");
295
296 size_t young_live = young_gen->used_in_bytes();
297 size_t eden_live = young_gen->eden_space()->used_in_bytes();
298 size_t old_live = old_gen->used_in_bytes();
299 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
300 size_t max_old_gen_size = old_gen->max_gen_size();
301 size_t max_eden_size = young_gen->max_size() -
302 young_gen->from_space()->capacity_in_bytes() -
303 young_gen->to_space()->capacity_in_bytes();
304
305 // Used for diagnostics
306 size_policy->clear_generation_free_space_flags();
307
308 size_policy->compute_generations_free_space(young_live,
309 eden_live,
310 old_live,
311 cur_eden,
312 max_old_gen_size,
313 max_eden_size,
314 true /* full gc*/);
315
316 size_policy->check_gc_overhead_limit(young_live,
317 eden_live,
318 max_old_gen_size,
319 max_eden_size,
320 true /* full gc*/,
321 gc_cause,
322 heap->collector_policy());
323
324 size_policy->decay_supplemental_growth(true /* full gc*/);
325
326 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
327
328 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
329 size_policy->calculated_survivor_size_in_bytes());
330 }
331 if (PrintAdaptiveSizePolicy) {
332 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
333 heap->total_collections());
334 }
335 }
336
337 if (UsePerfData) {
338 heap->gc_policy_counters()->update_counters();
339 heap->gc_policy_counters()->update_old_capacity(
340 old_gen->capacity_in_bytes());
341 heap->gc_policy_counters()->update_young_capacity(
342 young_gen->capacity_in_bytes());
343 }
344
345 heap->resize_all_tlabs();
346
347 // We collected the heap, recalculate the metaspace capacity
348 MetaspaceGC::compute_new_size();
349
350 if (TraceOldGenTime) accumulated_time()->stop();
351
352 if (PrintGC) {
353 if (PrintGCDetails) {
354 // Don't print a GC timestamp here. This is after the GC so
355 // would be confusing.
356 young_gen->print_used_change(young_gen_prev_used);
357 old_gen->print_used_change(old_gen_prev_used);
358 }
359 heap->print_heap_change(prev_used);
360 if (PrintGCDetails) {
361 MetaspaceAux::print_metaspace_change(metadata_prev_used);
362 }
363 }
364
365 // Track memory usage and detect low memory
366 MemoryService::track_memory_usage();
367 heap->update_counters();
368 }
369
370 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
371 HandleMark hm; // Discard invalid handles created during verification
372 Universe::verify(" VerifyAfterGC:");
373 }
374
375 // Re-verify object start arrays
376 if (VerifyObjectStartArray &&
377 VerifyAfterGC) {
378 old_gen->verify_object_start_array();
379 }
380
381 if (ZapUnusedHeapArea) {
382 old_gen->object_space()->check_mangled_unused_area_complete();
383 }
384
385 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
386
387 heap->print_heap_after_gc();
388 heap->trace_heap_after_gc(_gc_tracer);
389
390 heap->post_full_gc_dump(_gc_timer);
391
392 #ifdef TRACESPINNING
393 ParallelTaskTerminator::print_termination_counts();
394 #endif
395
396 _gc_timer->register_gc_end();
397
398 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
399
400 return true;
401 }
402
403 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
404 PSYoungGen* young_gen,
405 PSOldGen* old_gen) {
406 MutableSpace* const eden_space = young_gen->eden_space();
407 assert(!eden_space->is_empty(), "eden must be non-empty");
408 assert(young_gen->virtual_space()->alignment() ==
409 old_gen->virtual_space()->alignment(), "alignments do not match");
410
411 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
412 return false;
413 }
414
415 // Both generations must be completely committed.
416 if (young_gen->virtual_space()->uncommitted_size() != 0) {
417 return false;
418 }
419 if (old_gen->virtual_space()->uncommitted_size() != 0) {
420 return false;
421 }
422
423 // Figure out how much to take from eden. Include the average amount promoted
424 // in the total; otherwise the next young gen GC will simply bail out to a
425 // full GC.
426 const size_t alignment = old_gen->virtual_space()->alignment();
427 const size_t eden_used = eden_space->used_in_bytes();
428 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
429 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
430 const size_t eden_capacity = eden_space->capacity_in_bytes();
431
432 if (absorb_size >= eden_capacity) {
433 return false; // Must leave some space in eden.
434 }
435
436 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
437 if (new_young_size < young_gen->min_gen_size()) {
438 return false; // Respect young gen minimum size.
439 }
440
441 if (TraceAdaptiveGCBoundary && Verbose) {
442 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
443 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
444 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
445 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
446 absorb_size / K,
447 eden_capacity / K, (eden_capacity - absorb_size) / K,
448 young_gen->from_space()->used_in_bytes() / K,
449 young_gen->to_space()->used_in_bytes() / K,
450 young_gen->capacity_in_bytes() / K, new_young_size / K);
451 }
452
453 // Fill the unused part of the old gen.
454 MutableSpace* const old_space = old_gen->object_space();
455 HeapWord* const unused_start = old_space->top();
456 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
457
458 if (unused_words > 0) {
459 if (unused_words < CollectedHeap::min_fill_size()) {
460 return false; // If the old gen cannot be filled, must give up.
461 }
462 CollectedHeap::fill_with_objects(unused_start, unused_words);
463 }
464
465 // Take the live data from eden and set both top and end in the old gen to
466 // eden top. (Need to set end because reset_after_change() mangles the region
467 // from end to virtual_space->high() in debug builds).
468 HeapWord* const new_top = eden_space->top();
469 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
470 absorb_size);
471 young_gen->reset_after_change();
472 old_space->set_top(new_top);
473 old_space->set_end(new_top);
474 old_gen->reset_after_change();
475
476 // Update the object start array for the filler object and the data from eden.
477 ObjectStartArray* const start_array = old_gen->start_array();
478 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
479 start_array->allocate_block(p);
480 }
481
482 // Could update the promoted average here, but it is not typically updated at
483 // full GCs and the value to use is unclear. Something like
484 //
485 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
486
487 size_policy->set_bytes_absorbed_from_eden(absorb_size);
488 return true;
489 }
490
491 void PSMarkSweep::allocate_stacks() {
492 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
493 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
494
495 PSYoungGen* young_gen = heap->young_gen();
496
497 MutableSpace* to_space = young_gen->to_space();
498 _preserved_marks = (PreservedMark*)to_space->top();
499 _preserved_count = 0;
500
501 // We want to calculate the size in bytes first.
502 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
503 // Now divide by the size of a PreservedMark
504 _preserved_count_max /= sizeof(PreservedMark);
505 }
506
507
508 void PSMarkSweep::deallocate_stacks() {
509 _preserved_mark_stack.clear(true);
510 _preserved_oop_stack.clear(true);
511 _marking_stack.clear();
512 _objarray_stack.clear(true);
513 }
514
515 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
516 // Recursively traverse all live objects and mark them
517 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
518 trace(" 1");
519
520 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
521 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
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, _gc_tracer->gc_id());
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, _gc_tracer->gc_id());
579 trace("2");
580
581 // Now all live objects are marked, compute the new object addresses.
582
583 // It is not required that we traverse spaces in the same order in
584 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
585 // tracking expects us to do so. See comment under phase4.
586
587 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
588 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
589
590 PSOldGen* old_gen = heap->old_gen();
591
592 // Begin compacting into the old gen
593 PSMarkSweepDecorator::set_destination_decorator_tenured();
594
595 // This will also compact the young gen spaces.
596 old_gen->precompact();
597 }
598
599 // This should be moved to the shared markSweep code!
600 class PSAlwaysTrueClosure: public BoolObjectClosure {
601 public:
602 bool do_object_b(oop p) { return true; }
603 };
604 static PSAlwaysTrueClosure always_true;
605
606 void PSMarkSweep::mark_sweep_phase3() {
607 // Adjust the pointers to reflect the new locations
608 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
609 trace("3");
610
611 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
612 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
613
614 PSYoungGen* young_gen = heap->young_gen();
615 PSOldGen* old_gen = heap->old_gen();
616
617 // Need to clear claim bits before the tracing starts.
618 ClassLoaderDataGraph::clear_claimed_marks();
619
620 // General strong roots.
621 Universe::oops_do(adjust_pointer_closure());
622 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
623 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
624 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
625 ObjectSynchronizer::oops_do(adjust_pointer_closure());
626 FlatProfiler::oops_do(adjust_pointer_closure());
627 Management::oops_do(adjust_pointer_closure());
628 JvmtiExport::oops_do(adjust_pointer_closure());
629 SystemDictionary::oops_do(adjust_pointer_closure());
630 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
631
632 // Now adjust pointers in remaining weak roots. (All of which should
633 // have been cleared if they pointed to non-surviving objects.)
634 // Global (weak) JNI handles
635 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
636
637 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
638 CodeCache::blobs_do(&adjust_from_blobs);
639 StringTable::oops_do(adjust_pointer_closure());
640 ref_processor()->weak_oops_do(adjust_pointer_closure());
641 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
642
643 adjust_marks();
644
645 young_gen->adjust_pointers();
646 old_gen->adjust_pointers();
647 }
648
649 void PSMarkSweep::mark_sweep_phase4() {
650 EventMark m("4 compact heap");
651 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
652 trace("4");
653
654 // All pointers are now adjusted, move objects accordingly
655
656 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
657 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
658
659 PSYoungGen* young_gen = heap->young_gen();
660 PSOldGen* old_gen = heap->old_gen();
661
662 old_gen->compact();
663 young_gen->compact();
664 }
665
666 jlong PSMarkSweep::millis_since_last_gc() {
667 // We need a monotonically non-decreasing time in ms but
668 // os::javaTimeMillis() does not guarantee monotonicity.
669 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
670 jlong ret_val = now - _time_of_last_gc;
671 // XXX See note in genCollectedHeap::millis_since_last_gc().
672 if (ret_val < 0) {
673 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
674 return 0;
675 }
676 return ret_val;
677 }
678
679 void PSMarkSweep::reset_millis_since_last_gc() {
680 // We need a monotonically non-decreasing time in ms but
681 // os::javaTimeMillis() does not guarantee monotonicity.
682 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
683 }