Fri, 01 Nov 2013 17:09:38 +0100
8016309: assert(eden_size > 0 && survivor_size > 0) failed: just checking
7057939: jmap shows MaxNewSize=4GB when Java is using parallel collector
Summary: Major cleanup of the collectorpolicy classes
Reviewed-by: tschatzl, jcoomes
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).
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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.
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23 */
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"
57 elapsedTimer PSMarkSweep::_accumulated_time;
58 jlong PSMarkSweep::_time_of_last_gc = 0;
59 CollectorCounters* PSMarkSweep::_counters = NULL;
61 void PSMarkSweep::initialize() {
62 MemRegion mr = Universe::heap()->reserved_region();
63 _ref_processor = new ReferenceProcessor(mr); // a vanilla ref proc
64 _counters = new CollectorCounters("PSMarkSweep", 1);
65 }
67 // This method contains all heap specific policy for invoking mark sweep.
68 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
69 // the heap. It will do nothing further. If we need to bail out for policy
70 // reasons, scavenge before full gc, or any other specialized behavior, it
71 // needs to be added here.
72 //
73 // Note that this method should only be called from the vm_thread while
74 // at a safepoint!
75 //
76 // Note that the all_soft_refs_clear flag in the collector policy
77 // may be true because this method can be called without intervening
78 // activity. For example when the heap space is tight and full measure
79 // are being taken to free space.
81 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
82 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
83 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
84 assert(!Universe::heap()->is_gc_active(), "not reentrant");
86 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
87 GCCause::Cause gc_cause = heap->gc_cause();
88 PSAdaptiveSizePolicy* policy = heap->size_policy();
89 IsGCActiveMark mark;
91 if (ScavengeBeforeFullGC) {
92 PSScavenge::invoke_no_policy();
93 }
95 const bool clear_all_soft_refs =
96 heap->collector_policy()->should_clear_all_soft_refs();
98 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount;
99 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
100 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
101 }
103 // This method contains no policy. You should probably
104 // be calling invoke() instead.
105 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
106 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
107 assert(ref_processor() != NULL, "Sanity");
109 if (GC_locker::check_active_before_gc()) {
110 return false;
111 }
113 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
114 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
115 GCCause::Cause gc_cause = heap->gc_cause();
117 _gc_timer->register_gc_start(os::elapsed_counter());
118 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start());
120 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
122 // The scope of casr should end after code that can change
123 // CollectorPolicy::_should_clear_all_soft_refs.
124 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
126 PSYoungGen* young_gen = heap->young_gen();
127 PSOldGen* old_gen = heap->old_gen();
129 // Increment the invocation count
130 heap->increment_total_collections(true /* full */);
132 // Save information needed to minimize mangling
133 heap->record_gen_tops_before_GC();
135 // We need to track unique mark sweep invocations as well.
136 _total_invocations++;
138 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
140 heap->print_heap_before_gc();
141 heap->trace_heap_before_gc(_gc_tracer);
143 // Fill in TLABs
144 heap->accumulate_statistics_all_tlabs();
145 heap->ensure_parsability(true); // retire TLABs
147 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
148 HandleMark hm; // Discard invalid handles created during verification
149 Universe::verify(" VerifyBeforeGC:");
150 }
152 // Verify object start arrays
153 if (VerifyObjectStartArray &&
154 VerifyBeforeGC) {
155 old_gen->verify_object_start_array();
156 }
158 heap->pre_full_gc_dump(_gc_timer);
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;
165 {
166 HandleMark hm;
168 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
169 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
170 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
171 TraceCollectorStats tcs(counters());
172 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
174 if (TraceGen1Time) accumulated_time()->start();
176 // Let the size policy know we're starting
177 size_policy->major_collection_begin();
179 CodeCache::gc_prologue();
180 Threads::gc_prologue();
181 BiasedLocking::preserve_marks();
183 // Capture heap size before collection for printing.
184 size_t prev_used = heap->used();
186 // Capture metadata size before collection for sizing.
187 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
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();
193 allocate_stacks();
195 COMPILER2_PRESENT(DerivedPointerTable::clear());
197 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
198 ref_processor()->setup_policy(clear_all_softrefs);
200 mark_sweep_phase1(clear_all_softrefs);
202 mark_sweep_phase2();
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));
208 mark_sweep_phase3();
210 mark_sweep_phase4();
212 restore_marks();
214 deallocate_stacks();
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 }
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 }
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();
231 survivors_empty = young_gen->from_space()->is_empty() &&
232 young_gen->to_space()->is_empty();
233 young_gen_empty = eden_empty && survivors_empty;
235 BarrierSet* bs = heap->barrier_set();
236 if (bs->is_a(BarrierSet::ModRef)) {
237 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
238 MemRegion old_mr = heap->old_gen()->reserved();
239 if (young_gen_empty) {
240 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
241 } else {
242 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
243 }
244 }
246 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
247 ClassLoaderDataGraph::purge();
248 MetaspaceAux::verify_metrics();
250 BiasedLocking::restore_marks();
251 Threads::gc_epilogue();
252 CodeCache::gc_epilogue();
253 JvmtiExport::gc_epilogue();
255 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
257 ref_processor()->enqueue_discovered_references(NULL);
259 // Update time of last GC
260 reset_millis_since_last_gc();
262 // Let the size policy know we're done
263 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
265 if (UseAdaptiveSizePolicy) {
267 if (PrintAdaptiveSizePolicy) {
268 gclog_or_tty->print("AdaptiveSizeStart: ");
269 gclog_or_tty->stamp();
270 gclog_or_tty->print_cr(" collection: %d ",
271 heap->total_collections());
272 if (Verbose) {
273 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
274 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
275 }
276 }
278 // Don't check if the size_policy is ready here. Let
279 // the size_policy check that internally.
280 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
281 ((gc_cause != GCCause::_java_lang_system_gc) ||
282 UseAdaptiveSizePolicyWithSystemGC)) {
283 // Calculate optimal free space amounts
284 assert(young_gen->max_size() >
285 young_gen->from_space()->capacity_in_bytes() +
286 young_gen->to_space()->capacity_in_bytes(),
287 "Sizes of space in young gen are out-of-bounds");
289 size_t young_live = young_gen->used_in_bytes();
290 size_t eden_live = young_gen->eden_space()->used_in_bytes();
291 size_t old_live = old_gen->used_in_bytes();
292 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
293 size_t max_old_gen_size = old_gen->max_gen_size();
294 size_t max_eden_size = young_gen->max_size() -
295 young_gen->from_space()->capacity_in_bytes() -
296 young_gen->to_space()->capacity_in_bytes();
298 // Used for diagnostics
299 size_policy->clear_generation_free_space_flags();
301 size_policy->compute_generations_free_space(young_live,
302 eden_live,
303 old_live,
304 cur_eden,
305 max_old_gen_size,
306 max_eden_size,
307 true /* full gc*/);
309 size_policy->check_gc_overhead_limit(young_live,
310 eden_live,
311 max_old_gen_size,
312 max_eden_size,
313 true /* full gc*/,
314 gc_cause,
315 heap->collector_policy());
317 size_policy->decay_supplemental_growth(true /* full gc*/);
319 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
321 // Don't resize the young generation at an major collection. A
322 // desired young generation size may have been calculated but
323 // resizing the young generation complicates the code because the
324 // resizing of the old generation may have moved the boundary
325 // between the young generation and the old generation. Let the
326 // young generation resizing happen at the minor collections.
327 }
328 if (PrintAdaptiveSizePolicy) {
329 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
330 heap->total_collections());
331 }
332 }
334 if (UsePerfData) {
335 heap->gc_policy_counters()->update_counters();
336 heap->gc_policy_counters()->update_old_capacity(
337 old_gen->capacity_in_bytes());
338 heap->gc_policy_counters()->update_young_capacity(
339 young_gen->capacity_in_bytes());
340 }
342 heap->resize_all_tlabs();
344 // We collected the heap, recalculate the metaspace capacity
345 MetaspaceGC::compute_new_size();
347 if (TraceGen1Time) accumulated_time()->stop();
349 if (PrintGC) {
350 if (PrintGCDetails) {
351 // Don't print a GC timestamp here. This is after the GC so
352 // would be confusing.
353 young_gen->print_used_change(young_gen_prev_used);
354 old_gen->print_used_change(old_gen_prev_used);
355 }
356 heap->print_heap_change(prev_used);
357 if (PrintGCDetails) {
358 MetaspaceAux::print_metaspace_change(metadata_prev_used);
359 }
360 }
362 // Track memory usage and detect low memory
363 MemoryService::track_memory_usage();
364 heap->update_counters();
365 }
367 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
368 HandleMark hm; // Discard invalid handles created during verification
369 Universe::verify(" VerifyAfterGC:");
370 }
372 // Re-verify object start arrays
373 if (VerifyObjectStartArray &&
374 VerifyAfterGC) {
375 old_gen->verify_object_start_array();
376 }
378 if (ZapUnusedHeapArea) {
379 old_gen->object_space()->check_mangled_unused_area_complete();
380 }
382 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
384 heap->print_heap_after_gc();
385 heap->trace_heap_after_gc(_gc_tracer);
387 heap->post_full_gc_dump(_gc_timer);
389 #ifdef TRACESPINNING
390 ParallelTaskTerminator::print_termination_counts();
391 #endif
393 _gc_timer->register_gc_end(os::elapsed_counter());
395 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
397 return true;
398 }
400 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
401 PSYoungGen* young_gen,
402 PSOldGen* old_gen) {
403 MutableSpace* const eden_space = young_gen->eden_space();
404 assert(!eden_space->is_empty(), "eden must be non-empty");
405 assert(young_gen->virtual_space()->alignment() ==
406 old_gen->virtual_space()->alignment(), "alignments do not match");
408 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
409 return false;
410 }
412 // Both generations must be completely committed.
413 if (young_gen->virtual_space()->uncommitted_size() != 0) {
414 return false;
415 }
416 if (old_gen->virtual_space()->uncommitted_size() != 0) {
417 return false;
418 }
420 // Figure out how much to take from eden. Include the average amount promoted
421 // in the total; otherwise the next young gen GC will simply bail out to a
422 // full GC.
423 const size_t alignment = old_gen->virtual_space()->alignment();
424 const size_t eden_used = eden_space->used_in_bytes();
425 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
426 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
427 const size_t eden_capacity = eden_space->capacity_in_bytes();
429 if (absorb_size >= eden_capacity) {
430 return false; // Must leave some space in eden.
431 }
433 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
434 if (new_young_size < young_gen->min_gen_size()) {
435 return false; // Respect young gen minimum size.
436 }
438 if (TraceAdaptiveGCBoundary && Verbose) {
439 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
440 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
441 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
442 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
443 absorb_size / K,
444 eden_capacity / K, (eden_capacity - absorb_size) / K,
445 young_gen->from_space()->used_in_bytes() / K,
446 young_gen->to_space()->used_in_bytes() / K,
447 young_gen->capacity_in_bytes() / K, new_young_size / K);
448 }
450 // Fill the unused part of the old gen.
451 MutableSpace* const old_space = old_gen->object_space();
452 HeapWord* const unused_start = old_space->top();
453 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
455 if (unused_words > 0) {
456 if (unused_words < CollectedHeap::min_fill_size()) {
457 return false; // If the old gen cannot be filled, must give up.
458 }
459 CollectedHeap::fill_with_objects(unused_start, unused_words);
460 }
462 // Take the live data from eden and set both top and end in the old gen to
463 // eden top. (Need to set end because reset_after_change() mangles the region
464 // from end to virtual_space->high() in debug builds).
465 HeapWord* const new_top = eden_space->top();
466 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
467 absorb_size);
468 young_gen->reset_after_change();
469 old_space->set_top(new_top);
470 old_space->set_end(new_top);
471 old_gen->reset_after_change();
473 // Update the object start array for the filler object and the data from eden.
474 ObjectStartArray* const start_array = old_gen->start_array();
475 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
476 start_array->allocate_block(p);
477 }
479 // Could update the promoted average here, but it is not typically updated at
480 // full GCs and the value to use is unclear. Something like
481 //
482 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
484 size_policy->set_bytes_absorbed_from_eden(absorb_size);
485 return true;
486 }
488 void PSMarkSweep::allocate_stacks() {
489 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
490 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
492 PSYoungGen* young_gen = heap->young_gen();
494 MutableSpace* to_space = young_gen->to_space();
495 _preserved_marks = (PreservedMark*)to_space->top();
496 _preserved_count = 0;
498 // We want to calculate the size in bytes first.
499 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
500 // Now divide by the size of a PreservedMark
501 _preserved_count_max /= sizeof(PreservedMark);
502 }
505 void PSMarkSweep::deallocate_stacks() {
506 _preserved_mark_stack.clear(true);
507 _preserved_oop_stack.clear(true);
508 _marking_stack.clear();
509 _objarray_stack.clear(true);
510 }
512 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
513 // Recursively traverse all live objects and mark them
514 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer);
515 trace(" 1");
517 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
518 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
520 // Need to clear claim bits before the tracing starts.
521 ClassLoaderDataGraph::clear_claimed_marks();
523 // General strong roots.
524 {
525 ParallelScavengeHeap::ParStrongRootsScope psrs;
526 Universe::oops_do(mark_and_push_closure());
527 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
528 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure());
529 CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
530 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob);
531 ObjectSynchronizer::oops_do(mark_and_push_closure());
532 FlatProfiler::oops_do(mark_and_push_closure());
533 Management::oops_do(mark_and_push_closure());
534 JvmtiExport::oops_do(mark_and_push_closure());
535 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
536 ClassLoaderDataGraph::always_strong_oops_do(mark_and_push_closure(), follow_klass_closure(), true);
537 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
538 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
539 }
541 // Flush marking stack.
542 follow_stack();
544 // Process reference objects found during marking
545 {
546 ref_processor()->setup_policy(clear_all_softrefs);
547 const ReferenceProcessorStats& stats =
548 ref_processor()->process_discovered_references(
549 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer);
550 gc_tracer()->report_gc_reference_stats(stats);
551 }
553 // This is the point where the entire marking should have completed.
554 assert(_marking_stack.is_empty(), "Marking should have completed");
556 // Unload classes and purge the SystemDictionary.
557 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
559 // Unload nmethods.
560 CodeCache::do_unloading(is_alive_closure(), purged_class);
562 // Prune dead klasses from subklass/sibling/implementor lists.
563 Klass::clean_weak_klass_links(is_alive_closure());
565 // Delete entries for dead interned strings.
566 StringTable::unlink(is_alive_closure());
568 // Clean up unreferenced symbols in symbol table.
569 SymbolTable::unlink();
570 _gc_tracer->report_object_count_after_gc(is_alive_closure());
571 }
574 void PSMarkSweep::mark_sweep_phase2() {
575 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer);
576 trace("2");
578 // Now all live objects are marked, compute the new object addresses.
580 // It is not required that we traverse spaces in the same order in
581 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
582 // tracking expects us to do so. See comment under phase4.
584 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
585 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
587 PSOldGen* old_gen = heap->old_gen();
589 // Begin compacting into the old gen
590 PSMarkSweepDecorator::set_destination_decorator_tenured();
592 // This will also compact the young gen spaces.
593 old_gen->precompact();
594 }
596 // This should be moved to the shared markSweep code!
597 class PSAlwaysTrueClosure: public BoolObjectClosure {
598 public:
599 bool do_object_b(oop p) { return true; }
600 };
601 static PSAlwaysTrueClosure always_true;
603 void PSMarkSweep::mark_sweep_phase3() {
604 // Adjust the pointers to reflect the new locations
605 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer);
606 trace("3");
608 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
609 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
611 PSYoungGen* young_gen = heap->young_gen();
612 PSOldGen* old_gen = heap->old_gen();
614 // Need to clear claim bits before the tracing starts.
615 ClassLoaderDataGraph::clear_claimed_marks();
617 // General strong roots.
618 Universe::oops_do(adjust_pointer_closure());
619 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
620 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
621 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
622 ObjectSynchronizer::oops_do(adjust_pointer_closure());
623 FlatProfiler::oops_do(adjust_pointer_closure());
624 Management::oops_do(adjust_pointer_closure());
625 JvmtiExport::oops_do(adjust_pointer_closure());
626 // SO_AllClasses
627 SystemDictionary::oops_do(adjust_pointer_closure());
628 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
630 // Now adjust pointers in remaining weak roots. (All of which should
631 // have been cleared if they pointed to non-surviving objects.)
632 // Global (weak) JNI handles
633 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
635 CodeCache::oops_do(adjust_pointer_closure());
636 StringTable::oops_do(adjust_pointer_closure());
637 ref_processor()->weak_oops_do(adjust_pointer_closure());
638 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
640 adjust_marks();
642 young_gen->adjust_pointers();
643 old_gen->adjust_pointers();
644 }
646 void PSMarkSweep::mark_sweep_phase4() {
647 EventMark m("4 compact heap");
648 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer);
649 trace("4");
651 // All pointers are now adjusted, move objects accordingly
653 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
654 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
656 PSYoungGen* young_gen = heap->young_gen();
657 PSOldGen* old_gen = heap->old_gen();
659 old_gen->compact();
660 young_gen->compact();
661 }
663 jlong PSMarkSweep::millis_since_last_gc() {
664 // We need a monotonically non-deccreasing time in ms but
665 // os::javaTimeMillis() does not guarantee monotonicity.
666 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
667 jlong ret_val = now - _time_of_last_gc;
668 // XXX See note in genCollectedHeap::millis_since_last_gc().
669 if (ret_val < 0) {
670 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
671 return 0;
672 }
673 return ret_val;
674 }
676 void PSMarkSweep::reset_millis_since_last_gc() {
677 // We need a monotonically non-deccreasing time in ms but
678 // os::javaTimeMillis() does not guarantee monotonicity.
679 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
680 }