1 /*
2 * Copyright (c) 2001, 2013, 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/symbolTable.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 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
171 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
172 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
173 TraceCollectorStats tcs(counters());
174 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
175
176 if (TraceGen1Time) accumulated_time()->start();
177
178 // Let the size policy know we're starting
179 size_policy->major_collection_begin();
180
181 CodeCache::gc_prologue();
182 Threads::gc_prologue();
183 BiasedLocking::preserve_marks();
184
185 // Capture heap size before collection for printing.
186 size_t prev_used = heap->used();
187
188 // Capture metadata size before collection for sizing.
189 size_t metadata_prev_used = MetaspaceAux::used_bytes();
190
191 // For PrintGCDetails
192 size_t old_gen_prev_used = old_gen->used_in_bytes();
193 size_t young_gen_prev_used = young_gen->used_in_bytes();
194
195 allocate_stacks();
196
197 COMPILER2_PRESENT(DerivedPointerTable::clear());
198
199 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
200 ref_processor()->setup_policy(clear_all_softrefs);
201
202 mark_sweep_phase1(clear_all_softrefs);
203
204 mark_sweep_phase2();
205
206 // Don't add any more derived pointers during phase3
207 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
208 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
209
210 mark_sweep_phase3();
211
212 mark_sweep_phase4();
213
214 restore_marks();
215
216 deallocate_stacks();
217
218 if (ZapUnusedHeapArea) {
219 // Do a complete mangle (top to end) because the usage for
220 // scratch does not maintain a top pointer.
221 young_gen->to_space()->mangle_unused_area_complete();
222 }
223
224 eden_empty = young_gen->eden_space()->is_empty();
225 if (!eden_empty) {
226 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
227 }
228
229 // Update heap occupancy information which is used as
230 // input to soft ref clearing policy at the next gc.
231 Universe::update_heap_info_at_gc();
232
233 survivors_empty = young_gen->from_space()->is_empty() &&
234 young_gen->to_space()->is_empty();
235 young_gen_empty = eden_empty && survivors_empty;
236
237 BarrierSet* bs = heap->barrier_set();
238 if (bs->is_a(BarrierSet::ModRef)) {
239 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
240 MemRegion old_mr = heap->old_gen()->reserved();
241 if (young_gen_empty) {
242 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
243 } else {
244 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
245 }
246 }
247
248 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
249 ClassLoaderDataGraph::purge();
250 MetaspaceAux::verify_metrics();
251
252 BiasedLocking::restore_marks();
253 Threads::gc_epilogue();
254 CodeCache::gc_epilogue();
255 JvmtiExport::gc_epilogue();
256
257 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
258
259 ref_processor()->enqueue_discovered_references(NULL);
260
261 // Update time of last GC
262 reset_millis_since_last_gc();
263
264 // Let the size policy know we're done
265 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
266
267 if (UseAdaptiveSizePolicy) {
268
269 if (PrintAdaptiveSizePolicy) {
270 gclog_or_tty->print("AdaptiveSizeStart: ");
271 gclog_or_tty->stamp();
272 gclog_or_tty->print_cr(" collection: %d ",
273 heap->total_collections());
274 if (Verbose) {
275 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
276 " young_gen_capacity: " SIZE_FORMAT,
277 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
278 }
279 }
280
281 // Don't check if the size_policy is ready here. Let
282 // the size_policy check that internally.
283 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
284 ((gc_cause != GCCause::_java_lang_system_gc) ||
285 UseAdaptiveSizePolicyWithSystemGC)) {
286 // Swap the survivor spaces if from_space is empty. The
287 // resize_young_gen() called below is normally used after
288 // a successful young GC and swapping of survivor spaces;
289 // otherwise, it will fail to resize the young gen with
290 // the current implementation.
291 if (young_gen->from_space()->is_empty()) {
292 young_gen->from_space()->clear(SpaceDecorator::Mangle);
293 young_gen->swap_spaces();
294 }
295
296 // Calculate optimal free space amounts
297 assert(young_gen->max_size() >
298 young_gen->from_space()->capacity_in_bytes() +
299 young_gen->to_space()->capacity_in_bytes(),
300 "Sizes of space in young gen are out-of-bounds");
301
302 size_t young_live = young_gen->used_in_bytes();
303 size_t eden_live = young_gen->eden_space()->used_in_bytes();
304 size_t old_live = old_gen->used_in_bytes();
305 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
306 size_t max_old_gen_size = old_gen->max_gen_size();
307 size_t max_eden_size = young_gen->max_size() -
308 young_gen->from_space()->capacity_in_bytes() -
309 young_gen->to_space()->capacity_in_bytes();
310
311 // Used for diagnostics
312 size_policy->clear_generation_free_space_flags();
313
314 size_policy->compute_generations_free_space(young_live,
315 eden_live,
316 old_live,
317 cur_eden,
318 max_old_gen_size,
319 max_eden_size,
320 true /* full gc*/);
321
322 size_policy->check_gc_overhead_limit(young_live,
323 eden_live,
324 max_old_gen_size,
325 max_eden_size,
326 true /* full gc*/,
327 gc_cause,
328 heap->collector_policy());
329
330 size_policy->decay_supplemental_growth(true /* full gc*/);
331
332 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
333
334 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
335 size_policy->calculated_survivor_size_in_bytes());
336 }
337 if (PrintAdaptiveSizePolicy) {
338 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
339 heap->total_collections());
340 }
341 }
342
343 if (UsePerfData) {
344 heap->gc_policy_counters()->update_counters();
345 heap->gc_policy_counters()->update_old_capacity(
346 old_gen->capacity_in_bytes());
347 heap->gc_policy_counters()->update_young_capacity(
348 young_gen->capacity_in_bytes());
349 }
350
351 heap->resize_all_tlabs();
352
353 // We collected the heap, recalculate the metaspace capacity
354 MetaspaceGC::compute_new_size();
355
356 if (TraceGen1Time) accumulated_time()->stop();
357
358 if (PrintGC) {
359 if (PrintGCDetails) {
360 // Don't print a GC timestamp here. This is after the GC so
361 // would be confusing.
362 young_gen->print_used_change(young_gen_prev_used);
363 old_gen->print_used_change(old_gen_prev_used);
364 }
365 heap->print_heap_change(prev_used);
366 if (PrintGCDetails) {
367 MetaspaceAux::print_metaspace_change(metadata_prev_used);
368 }
369 }
370
371 // Track memory usage and detect low memory
372 MemoryService::track_memory_usage();
373 heap->update_counters();
374 }
375
376 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
377 HandleMark hm; // Discard invalid handles created during verification
378 Universe::verify(" VerifyAfterGC:");
379 }
380
381 // Re-verify object start arrays
382 if (VerifyObjectStartArray &&
383 VerifyAfterGC) {
384 old_gen->verify_object_start_array();
385 }
386
387 if (ZapUnusedHeapArea) {
388 old_gen->object_space()->check_mangled_unused_area_complete();
389 }
390
391 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
392
393 heap->print_heap_after_gc();
394 heap->trace_heap_after_gc(_gc_tracer);
395
396 heap->post_full_gc_dump(_gc_timer);
397
398 #ifdef TRACESPINNING
399 ParallelTaskTerminator::print_termination_counts();
400 #endif
401
402 _gc_timer->register_gc_end();
403
404 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
405
406 return true;
407 }
408
409 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
410 PSYoungGen* young_gen,
411 PSOldGen* old_gen) {
412 MutableSpace* const eden_space = young_gen->eden_space();
413 assert(!eden_space->is_empty(), "eden must be non-empty");
414 assert(young_gen->virtual_space()->alignment() ==
415 old_gen->virtual_space()->alignment(), "alignments do not match");
416
417 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
418 return false;
419 }
420
421 // Both generations must be completely committed.
422 if (young_gen->virtual_space()->uncommitted_size() != 0) {
423 return false;
424 }
425 if (old_gen->virtual_space()->uncommitted_size() != 0) {
426 return false;
427 }
428
429 // Figure out how much to take from eden. Include the average amount promoted
430 // in the total; otherwise the next young gen GC will simply bail out to a
431 // full GC.
432 const size_t alignment = old_gen->virtual_space()->alignment();
433 const size_t eden_used = eden_space->used_in_bytes();
434 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
435 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
436 const size_t eden_capacity = eden_space->capacity_in_bytes();
437
438 if (absorb_size >= eden_capacity) {
439 return false; // Must leave some space in eden.
440 }
441
442 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
443 if (new_young_size < young_gen->min_gen_size()) {
444 return false; // Respect young gen minimum size.
445 }
446
447 if (TraceAdaptiveGCBoundary && Verbose) {
448 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
449 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
450 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
451 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
452 absorb_size / K,
453 eden_capacity / K, (eden_capacity - absorb_size) / K,
454 young_gen->from_space()->used_in_bytes() / K,
455 young_gen->to_space()->used_in_bytes() / K,
456 young_gen->capacity_in_bytes() / K, new_young_size / K);
457 }
458
459 // Fill the unused part of the old gen.
460 MutableSpace* const old_space = old_gen->object_space();
461 HeapWord* const unused_start = old_space->top();
462 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
463
464 if (unused_words > 0) {
465 if (unused_words < CollectedHeap::min_fill_size()) {
466 return false; // If the old gen cannot be filled, must give up.
467 }
468 CollectedHeap::fill_with_objects(unused_start, unused_words);
469 }
470
471 // Take the live data from eden and set both top and end in the old gen to
472 // eden top. (Need to set end because reset_after_change() mangles the region
473 // from end to virtual_space->high() in debug builds).
474 HeapWord* const new_top = eden_space->top();
475 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
476 absorb_size);
477 young_gen->reset_after_change();
478 old_space->set_top(new_top);
479 old_space->set_end(new_top);
480 old_gen->reset_after_change();
481
482 // Update the object start array for the filler object and the data from eden.
483 ObjectStartArray* const start_array = old_gen->start_array();
484 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
485 start_array->allocate_block(p);
486 }
487
488 // Could update the promoted average here, but it is not typically updated at
489 // full GCs and the value to use is unclear. Something like
490 //
491 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
492
493 size_policy->set_bytes_absorbed_from_eden(absorb_size);
494 return true;
495 }
496
497 void PSMarkSweep::allocate_stacks() {
498 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
499 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
500
501 PSYoungGen* young_gen = heap->young_gen();
502
503 MutableSpace* to_space = young_gen->to_space();
504 _preserved_marks = (PreservedMark*)to_space->top();
505 _preserved_count = 0;
506
507 // We want to calculate the size in bytes first.
508 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
509 // Now divide by the size of a PreservedMark
510 _preserved_count_max /= sizeof(PreservedMark);
511 }
512
513
514 void PSMarkSweep::deallocate_stacks() {
515 _preserved_mark_stack.clear(true);
516 _preserved_oop_stack.clear(true);
517 _marking_stack.clear();
518 _objarray_stack.clear(true);
519 }
520
521 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
522 // Recursively traverse all live objects and mark them
523 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer);
524 trace(" 1");
525
526 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
527 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
528
529 // Need to clear claim bits before the tracing starts.
530 ClassLoaderDataGraph::clear_claimed_marks();
531
532 // General strong roots.
533 {
534 ParallelScavengeHeap::ParStrongRootsScope psrs;
535 Universe::oops_do(mark_and_push_closure());
536 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
537 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
538 CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
539 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
540 ObjectSynchronizer::oops_do(mark_and_push_closure());
541 FlatProfiler::oops_do(mark_and_push_closure());
542 Management::oops_do(mark_and_push_closure());
543 JvmtiExport::oops_do(mark_and_push_closure());
544 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
545 ClassLoaderDataGraph::always_strong_oops_do(mark_and_push_closure(), follow_klass_closure(), true);
546 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
547 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
548 }
549
550 // Flush marking stack.
551 follow_stack();
552
553 // Process reference objects found during marking
554 {
555 ref_processor()->setup_policy(clear_all_softrefs);
556 const ReferenceProcessorStats& stats =
557 ref_processor()->process_discovered_references(
558 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer);
559 gc_tracer()->report_gc_reference_stats(stats);
560 }
561
562 // This is the point where the entire marking should have completed.
563 assert(_marking_stack.is_empty(), "Marking should have completed");
564
565 // Unload classes and purge the SystemDictionary.
566 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
567
568 // Unload nmethods.
569 CodeCache::do_unloading(is_alive_closure(), purged_class);
570
571 // Prune dead klasses from subklass/sibling/implementor lists.
572 Klass::clean_weak_klass_links(is_alive_closure());
573
574 // Delete entries for dead interned strings.
575 StringTable::unlink(is_alive_closure());
576
577 // Clean up unreferenced symbols in symbol table.
578 SymbolTable::unlink();
579 _gc_tracer->report_object_count_after_gc(is_alive_closure());
580 }
581
582
583 void PSMarkSweep::mark_sweep_phase2() {
584 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer);
585 trace("2");
586
587 // Now all live objects are marked, compute the new object addresses.
588
589 // It is not required that we traverse spaces in the same order in
590 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
591 // tracking expects us to do so. See comment under phase4.
592
593 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
594 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
595
596 PSOldGen* old_gen = heap->old_gen();
597
598 // Begin compacting into the old gen
599 PSMarkSweepDecorator::set_destination_decorator_tenured();
600
601 // This will also compact the young gen spaces.
602 old_gen->precompact();
603 }
604
605 // This should be moved to the shared markSweep code!
606 class PSAlwaysTrueClosure: public BoolObjectClosure {
607 public:
608 bool do_object_b(oop p) { return true; }
609 };
610 static PSAlwaysTrueClosure always_true;
611
612 void PSMarkSweep::mark_sweep_phase3() {
613 // Adjust the pointers to reflect the new locations
614 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer);
615 trace("3");
616
617 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
618 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
619
620 PSYoungGen* young_gen = heap->young_gen();
621 PSOldGen* old_gen = heap->old_gen();
622
623 // Need to clear claim bits before the tracing starts.
624 ClassLoaderDataGraph::clear_claimed_marks();
625
626 // General strong roots.
627 Universe::oops_do(adjust_pointer_closure());
628 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
629 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
630 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
631 ObjectSynchronizer::oops_do(adjust_pointer_closure());
632 FlatProfiler::oops_do(adjust_pointer_closure());
633 Management::oops_do(adjust_pointer_closure());
634 JvmtiExport::oops_do(adjust_pointer_closure());
635 // SO_AllClasses
636 SystemDictionary::oops_do(adjust_pointer_closure());
637 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
638
639 // Now adjust pointers in remaining weak roots. (All of which should
640 // have been cleared if they pointed to non-surviving objects.)
641 // Global (weak) JNI handles
642 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
643
644 CodeCache::oops_do(adjust_pointer_closure());
645 StringTable::oops_do(adjust_pointer_closure());
646 ref_processor()->weak_oops_do(adjust_pointer_closure());
647 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
648
649 adjust_marks();
650
651 young_gen->adjust_pointers();
652 old_gen->adjust_pointers();
653 }
654
655 void PSMarkSweep::mark_sweep_phase4() {
656 EventMark m("4 compact heap");
657 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer);
658 trace("4");
659
660 // All pointers are now adjusted, move objects accordingly
661
662 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
663 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
664
665 PSYoungGen* young_gen = heap->young_gen();
666 PSOldGen* old_gen = heap->old_gen();
667
668 old_gen->compact();
669 young_gen->compact();
670 }
671
672 jlong PSMarkSweep::millis_since_last_gc() {
673 // We need a monotonically non-decreasing time in ms but
674 // os::javaTimeMillis() does not guarantee monotonicity.
675 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
676 jlong ret_val = now - _time_of_last_gc;
677 // XXX See note in genCollectedHeap::millis_since_last_gc().
678 if (ret_val < 0) {
679 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
680 return 0;
681 }
682 return ret_val;
683 }
684
685 void PSMarkSweep::reset_millis_since_last_gc() {
686 // We need a monotonically non-decreasing time in ms but
687 // os::javaTimeMillis() does not guarantee monotonicity.
688 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
689 }