1
2 /*
3 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "code/codeCache.hpp"
30 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
31 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
32 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
33 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
34 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
35 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
36 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
37 #include "gc_implementation/shared/gcHeapSummary.hpp"
38 #include "gc_implementation/shared/gcTimer.hpp"
39 #include "gc_implementation/shared/gcTrace.hpp"
40 #include "gc_implementation/shared/gcTraceTime.hpp"
41 #include "gc_implementation/shared/isGCActiveMark.hpp"
42 #include "gc_implementation/shared/markSweep.hpp"
43 #include "gc_implementation/shared/spaceDecorator.hpp"
44 #include "gc_interface/gcCause.hpp"
45 #include "memory/gcLocker.inline.hpp"
46 #include "memory/referencePolicy.hpp"
47 #include "memory/referenceProcessor.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 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
59
60 elapsedTimer PSMarkSweep::_accumulated_time;
61 jlong PSMarkSweep::_time_of_last_gc = 0;
62 CollectorCounters* PSMarkSweep::_counters = NULL;
63
64 void PSMarkSweep::initialize() {
65 MemRegion mr = Universe::heap()->reserved_region();
66 _ref_processor = new ReferenceProcessor(mr); // a vanilla ref proc
67 _counters = new CollectorCounters("PSMarkSweep", 1);
68 }
69
70 // This method contains all heap specific policy for invoking mark sweep.
71 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
72 // the heap. It will do nothing further. If we need to bail out for policy
73 // reasons, scavenge before full gc, or any other specialized behavior, it
74 // needs to be added here.
75 //
76 // Note that this method should only be called from the vm_thread while
77 // at a safepoint!
78 //
79 // Note that the all_soft_refs_clear flag in the collector policy
80 // may be true because this method can be called without intervening
81 // activity. For example when the heap space is tight and full measure
82 // are being taken to free space.
83
84 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
85 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
86 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
87 assert(!Universe::heap()->is_gc_active(), "not reentrant");
88
89 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
90 GCCause::Cause gc_cause = heap->gc_cause();
91 PSAdaptiveSizePolicy* policy = heap->size_policy();
92 IsGCActiveMark mark;
93
94 if (ScavengeBeforeFullGC) {
95 PSScavenge::invoke_no_policy();
96 }
97
98 const bool clear_all_soft_refs =
99 heap->collector_policy()->should_clear_all_soft_refs();
100
101 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
102 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
103 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
104 }
105
106 // This method contains no policy. You should probably
107 // be calling invoke() instead.
108 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
109 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
110 assert(ref_processor() != NULL, "Sanity");
111
112 if (GC_locker::check_active_before_gc()) {
113 return false;
114 }
115
116 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
117 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
118 GCCause::Cause gc_cause = heap->gc_cause();
119
120 _gc_timer->register_gc_start();
121 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
122
123 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
124
125 // The scope of casr should end after code that can change
126 // CollectorPolicy::_should_clear_all_soft_refs.
127 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
128
129 PSYoungGen* young_gen = heap->young_gen();
130 PSOldGen* old_gen = heap->old_gen();
131
132 // Increment the invocation count
133 heap->increment_total_collections(true /* full */);
134
135 // Save information needed to minimize mangling
136 heap->record_gen_tops_before_GC();
137
138 // We need to track unique mark sweep invocations as well.
139 _total_invocations++;
140
141 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
142
143 heap->print_heap_before_gc();
144 heap->trace_heap_before_gc(_gc_tracer);
145
146 // Fill in TLABs
147 heap->accumulate_statistics_all_tlabs();
148 heap->ensure_parsability(true); // retire TLABs
149
150 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
151 HandleMark hm; // Discard invalid handles created during verification
152 Universe::verify(" VerifyBeforeGC:");
153 }
154
155 // Verify object start arrays
156 if (VerifyObjectStartArray &&
157 VerifyBeforeGC) {
158 old_gen->verify_object_start_array();
159 }
160
161 heap->pre_full_gc_dump(_gc_timer);
162
163 // Filled in below to track the state of the young gen after the collection.
164 bool eden_empty;
165 bool survivors_empty;
166 bool young_gen_empty;
167
168 {
169 HandleMark hm;
170
171 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
172 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
173 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer->gc_id());
174 TraceCollectorStats tcs(counters());
175 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
176
177 if (TraceOldGenTime) accumulated_time()->start();
178
179 // Let the size policy know we're starting
180 size_policy->major_collection_begin();
181
182 CodeCache::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 CodeCache::gc_epilogue();
254 JvmtiExport::gc_epilogue();
255
256 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
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 ((gc_cause != GCCause::_java_lang_system_gc) ||
284 UseAdaptiveSizePolicyWithSystemGC)) {
285 // Swap the survivor spaces if from_space is empty. The
286 // resize_young_gen() called below is normally used after
287 // a successful young GC and swapping of survivor spaces;
288 // otherwise, it will fail to resize the young gen with
289 // the current implementation.
290 if (young_gen->from_space()->is_empty()) {
291 young_gen->from_space()->clear(SpaceDecorator::Mangle);
292 young_gen->swap_spaces();
293 }
294
295 // Calculate optimal free space amounts
296 assert(young_gen->max_size() >
297 young_gen->from_space()->capacity_in_bytes() +
298 young_gen->to_space()->capacity_in_bytes(),
299 "Sizes of space in young gen are out-of-bounds");
300
301 size_t young_live = young_gen->used_in_bytes();
302 size_t eden_live = young_gen->eden_space()->used_in_bytes();
303 size_t old_live = old_gen->used_in_bytes();
304 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
305 size_t max_old_gen_size = old_gen->max_gen_size();
306 size_t max_eden_size = young_gen->max_size() -
307 young_gen->from_space()->capacity_in_bytes() -
308 young_gen->to_space()->capacity_in_bytes();
309
310 // Used for diagnostics
311 size_policy->clear_generation_free_space_flags();
312
313 size_policy->compute_generations_free_space(young_live,
314 eden_live,
315 old_live,
316 cur_eden,
317 max_old_gen_size,
318 max_eden_size,
319 true /* full gc*/);
320
321 size_policy->check_gc_overhead_limit(young_live,
322 eden_live,
323 max_old_gen_size,
324 max_eden_size,
325 true /* full gc*/,
326 gc_cause,
327 heap->collector_policy());
328
329 size_policy->decay_supplemental_growth(true /* full gc*/);
330
331 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
332
333 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
334 size_policy->calculated_survivor_size_in_bytes());
335 }
336 if (PrintAdaptiveSizePolicy) {
337 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
338 heap->total_collections());
339 }
340 }
341
342 if (UsePerfData) {
343 heap->gc_policy_counters()->update_counters();
344 heap->gc_policy_counters()->update_old_capacity(
345 old_gen->capacity_in_bytes());
346 heap->gc_policy_counters()->update_young_capacity(
347 young_gen->capacity_in_bytes());
348 }
349
350 heap->resize_all_tlabs();
351
352 // We collected the heap, recalculate the metaspace capacity
353 MetaspaceGC::compute_new_size();
354
355 if (TraceOldGenTime) accumulated_time()->stop();
356
357 if (PrintGC) {
358 if (PrintGCDetails) {
359 // Don't print a GC timestamp here. This is after the GC so
360 // would be confusing.
361 young_gen->print_used_change(young_gen_prev_used);
362 old_gen->print_used_change(old_gen_prev_used);
363 }
364 heap->print_heap_change(prev_used);
365 if (PrintGCDetails) {
366 MetaspaceAux::print_metaspace_change(metadata_prev_used);
367 }
368 }
369
370 // Track memory usage and detect low memory
371 MemoryService::track_memory_usage();
372 heap->update_counters();
373 }
374
375 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
376 HandleMark hm; // Discard invalid handles created during verification
377 Universe::verify(" VerifyAfterGC:");
378 }
379
380 // Re-verify object start arrays
381 if (VerifyObjectStartArray &&
382 VerifyAfterGC) {
383 old_gen->verify_object_start_array();
384 }
385
386 if (ZapUnusedHeapArea) {
387 old_gen->object_space()->check_mangled_unused_area_complete();
388 }
389
390 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
391
392 heap->print_heap_after_gc();
393 heap->trace_heap_after_gc(_gc_tracer);
394
395 heap->post_full_gc_dump(_gc_timer);
396
397 #ifdef TRACESPINNING
398 ParallelTaskTerminator::print_termination_counts();
399 #endif
400
401 _gc_timer->register_gc_end();
402
403 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
404
405 return true;
406 }
407
408 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
409 PSYoungGen* young_gen,
410 PSOldGen* old_gen) {
411 MutableSpace* const eden_space = young_gen->eden_space();
412 assert(!eden_space->is_empty(), "eden must be non-empty");
413 assert(young_gen->virtual_space()->alignment() ==
414 old_gen->virtual_space()->alignment(), "alignments do not match");
415
416 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
417 return false;
418 }
419
420 // Both generations must be completely committed.
421 if (young_gen->virtual_space()->uncommitted_size() != 0) {
422 return false;
423 }
424 if (old_gen->virtual_space()->uncommitted_size() != 0) {
425 return false;
426 }
427
428 // Figure out how much to take from eden. Include the average amount promoted
429 // in the total; otherwise the next young gen GC will simply bail out to a
430 // full GC.
431 const size_t alignment = old_gen->virtual_space()->alignment();
432 const size_t eden_used = eden_space->used_in_bytes();
433 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
434 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
435 const size_t eden_capacity = eden_space->capacity_in_bytes();
436
437 if (absorb_size >= eden_capacity) {
438 return false; // Must leave some space in eden.
439 }
440
441 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
442 if (new_young_size < young_gen->min_gen_size()) {
443 return false; // Respect young gen minimum size.
444 }
445
446 if (TraceAdaptiveGCBoundary && Verbose) {
447 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
448 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
449 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
450 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
451 absorb_size / K,
452 eden_capacity / K, (eden_capacity - absorb_size) / K,
453 young_gen->from_space()->used_in_bytes() / K,
454 young_gen->to_space()->used_in_bytes() / K,
455 young_gen->capacity_in_bytes() / K, new_young_size / K);
456 }
457
458 // Fill the unused part of the old gen.
459 MutableSpace* const old_space = old_gen->object_space();
460 HeapWord* const unused_start = old_space->top();
461 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
462
463 if (unused_words > 0) {
464 if (unused_words < CollectedHeap::min_fill_size()) {
465 return false; // If the old gen cannot be filled, must give up.
466 }
467 CollectedHeap::fill_with_objects(unused_start, unused_words);
468 }
469
470 // Take the live data from eden and set both top and end in the old gen to
471 // eden top. (Need to set end because reset_after_change() mangles the region
472 // from end to virtual_space->high() in debug builds).
473 HeapWord* const new_top = eden_space->top();
474 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
475 absorb_size);
476 young_gen->reset_after_change();
477 old_space->set_top(new_top);
478 old_space->set_end(new_top);
479 old_gen->reset_after_change();
480
481 // Update the object start array for the filler object and the data from eden.
482 ObjectStartArray* const start_array = old_gen->start_array();
483 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
484 start_array->allocate_block(p);
485 }
486
487 // Could update the promoted average here, but it is not typically updated at
488 // full GCs and the value to use is unclear. Something like
489 //
490 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
491
492 size_policy->set_bytes_absorbed_from_eden(absorb_size);
493 return true;
494 }
495
496 void PSMarkSweep::allocate_stacks() {
497 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
498 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
499
500 PSYoungGen* young_gen = heap->young_gen();
501
502 MutableSpace* to_space = young_gen->to_space();
503 _preserved_marks = (PreservedMark*)to_space->top();
504 _preserved_count = 0;
505
506 // We want to calculate the size in bytes first.
507 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
508 // Now divide by the size of a PreservedMark
509 _preserved_count_max /= sizeof(PreservedMark);
510 }
511
512
513 void PSMarkSweep::deallocate_stacks() {
514 _preserved_mark_stack.clear(true);
515 _preserved_oop_stack.clear(true);
516 _marking_stack.clear();
517 _objarray_stack.clear(true);
518 }
519
520 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
521 // Recursively traverse all live objects and mark them
522 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
523 trace(" 1");
524
525 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
526 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
527
528 // Need to clear claim bits before the tracing starts.
529 ClassLoaderDataGraph::clear_claimed_marks();
530
531 // General strong roots.
532 {
533 ParallelScavengeHeap::ParStrongRootsScope psrs;
534 Universe::oops_do(mark_and_push_closure());
535 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
536 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
537 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations);
538 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
539 ObjectSynchronizer::oops_do(mark_and_push_closure());
540 FlatProfiler::oops_do(mark_and_push_closure());
541 Management::oops_do(mark_and_push_closure());
542 JvmtiExport::oops_do(mark_and_push_closure());
543 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
544 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure());
545 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
546 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
547 }
548
549 // Flush marking stack.
550 follow_stack();
551
552 // Process reference objects found during marking
553 {
554 ref_processor()->setup_policy(clear_all_softrefs);
555 const ReferenceProcessorStats& stats =
556 ref_processor()->process_discovered_references(
557 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer, _gc_tracer->gc_id());
558 gc_tracer()->report_gc_reference_stats(stats);
559 }
560
561 // This is the point where the entire marking should have completed.
562 assert(_marking_stack.is_empty(), "Marking should have completed");
563
564 // Unload classes and purge the SystemDictionary.
565 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
566
567 // Unload nmethods.
568 CodeCache::do_unloading(is_alive_closure(), purged_class);
569
570 // Prune dead klasses from subklass/sibling/implementor lists.
571 Klass::clean_weak_klass_links(is_alive_closure());
572
573 // Delete entries for dead interned strings.
574 StringTable::unlink(is_alive_closure());
575
576 // Clean up unreferenced symbols in symbol table.
577 SymbolTable::unlink();
578 _gc_tracer->report_object_count_after_gc(is_alive_closure());
579 }
580
581
582 void PSMarkSweep::mark_sweep_phase2() {
583 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
584 trace("2");
585
586 // Now all live objects are marked, compute the new object addresses.
587
588 // It is not required that we traverse spaces in the same order in
589 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
590 // tracking expects us to do so. See comment under phase4.
591
592 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
593 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
594
595 PSOldGen* old_gen = heap->old_gen();
596
597 // Begin compacting into the old gen
598 PSMarkSweepDecorator::set_destination_decorator_tenured();
599
600 // This will also compact the young gen spaces.
601 old_gen->precompact();
602 }
603
604 // This should be moved to the shared markSweep code!
605 class PSAlwaysTrueClosure: public BoolObjectClosure {
606 public:
607 bool do_object_b(oop p) { return true; }
608 };
609 static PSAlwaysTrueClosure always_true;
610
611 void PSMarkSweep::mark_sweep_phase3() {
612 // Adjust the pointers to reflect the new locations
613 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
614 trace("3");
615
616 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
617 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
618
619 PSYoungGen* young_gen = heap->young_gen();
620 PSOldGen* old_gen = heap->old_gen();
621
622 // Need to clear claim bits before the tracing starts.
623 ClassLoaderDataGraph::clear_claimed_marks();
624
625 // General strong roots.
626 Universe::oops_do(adjust_pointer_closure());
627 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
628 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
629 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
630 ObjectSynchronizer::oops_do(adjust_pointer_closure());
631 FlatProfiler::oops_do(adjust_pointer_closure());
632 Management::oops_do(adjust_pointer_closure());
633 JvmtiExport::oops_do(adjust_pointer_closure());
634 SystemDictionary::oops_do(adjust_pointer_closure());
635 ClassLoaderDataGraph::cld_do(adjust_cld_closure());
636
637 // Now adjust pointers in remaining weak roots. (All of which should
638 // have been cleared if they pointed to non-surviving objects.)
639 // Global (weak) JNI handles
640 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
641
642 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
643 CodeCache::blobs_do(&adjust_from_blobs);
644 StringTable::oops_do(adjust_pointer_closure());
645 ref_processor()->weak_oops_do(adjust_pointer_closure());
646 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
647
648 adjust_marks();
649
650 young_gen->adjust_pointers();
651 old_gen->adjust_pointers();
652 }
653
654 void PSMarkSweep::mark_sweep_phase4() {
655 EventMark m("4 compact heap");
656 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id());
657 trace("4");
658
659 // All pointers are now adjusted, move objects accordingly
660
661 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
662 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
663
664 PSYoungGen* young_gen = heap->young_gen();
665 PSOldGen* old_gen = heap->old_gen();
666
667 old_gen->compact();
668 young_gen->compact();
669 }
670
671 jlong PSMarkSweep::millis_since_last_gc() {
672 // We need a monotonically non-decreasing time in ms but
673 // os::javaTimeMillis() does not guarantee monotonicity.
674 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
675 jlong ret_val = now - _time_of_last_gc;
676 // XXX See note in genCollectedHeap::millis_since_last_gc().
677 if (ret_val < 0) {
678 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
679 return 0;
680 }
681 return ret_val;
682 }
683
684 void PSMarkSweep::reset_millis_since_last_gc() {
685 // We need a monotonically non-decreasing time in ms but
686 // os::javaTimeMillis() does not guarantee monotonicity.
687 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
688 }