1 /*
2 * Copyright (c) 2001, 2010, 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 "incls/_precompiled.incl"
26 #include "incls/_psMarkSweep.cpp.incl"
27
28 elapsedTimer PSMarkSweep::_accumulated_time;
29 unsigned int PSMarkSweep::_total_invocations = 0;
30 jlong PSMarkSweep::_time_of_last_gc = 0;
31 CollectorCounters* PSMarkSweep::_counters = NULL;
32
33 void PSMarkSweep::initialize() {
34 MemRegion mr = Universe::heap()->reserved_region();
35 _ref_processor = new ReferenceProcessor(mr,
36 true, // atomic_discovery
37 false); // mt_discovery
38 _counters = new CollectorCounters("PSMarkSweep", 1);
39 }
40
41 // This method contains all heap specific policy for invoking mark sweep.
42 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
43 // the heap. It will do nothing further. If we need to bail out for policy
44 // reasons, scavenge before full gc, or any other specialized behavior, it
45 // needs to be added here.
46 //
47 // Note that this method should only be called from the vm_thread while
48 // at a safepoint!
49 //
50 // Note that the all_soft_refs_clear flag in the collector policy
51 // may be true because this method can be called without intervening
52 // activity. For example when the heap space is tight and full measure
53 // are being taken to free space.
54
55 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
56 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
57 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
58 assert(!Universe::heap()->is_gc_active(), "not reentrant");
59
60 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
61 GCCause::Cause gc_cause = heap->gc_cause();
62 PSAdaptiveSizePolicy* policy = heap->size_policy();
63 IsGCActiveMark mark;
64
65 if (ScavengeBeforeFullGC) {
66 PSScavenge::invoke_no_policy();
67 }
68
69 const bool clear_all_soft_refs =
70 heap->collector_policy()->should_clear_all_soft_refs();
71
72 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount;
73 IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
74 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
75 }
76
77 // This method contains no policy. You should probably
78 // be calling invoke() instead.
79 void PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
80 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
81 assert(ref_processor() != NULL, "Sanity");
82
83 if (GC_locker::check_active_before_gc()) {
84 return;
85 }
86
87 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
88 GCCause::Cause gc_cause = heap->gc_cause();
89 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
90 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
91
92 // The scope of casr should end after code that can change
93 // CollectorPolicy::_should_clear_all_soft_refs.
94 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
95
96 PSYoungGen* young_gen = heap->young_gen();
97 PSOldGen* old_gen = heap->old_gen();
98 PSPermGen* perm_gen = heap->perm_gen();
99
100 // Increment the invocation count
101 heap->increment_total_collections(true /* full */);
102
103 // Save information needed to minimize mangling
104 heap->record_gen_tops_before_GC();
105
106 // We need to track unique mark sweep invocations as well.
107 _total_invocations++;
108
109 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
110
111 if (PrintHeapAtGC) {
112 Universe::print_heap_before_gc();
113 }
114
115 // Fill in TLABs
116 heap->accumulate_statistics_all_tlabs();
117 heap->ensure_parsability(true); // retire TLABs
118
119 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
120 HandleMark hm; // Discard invalid handles created during verification
121 gclog_or_tty->print(" VerifyBeforeGC:");
122 Universe::verify(true);
123 }
124
125 // Verify object start arrays
126 if (VerifyObjectStartArray &&
127 VerifyBeforeGC) {
128 old_gen->verify_object_start_array();
129 perm_gen->verify_object_start_array();
130 }
131
132 heap->pre_full_gc_dump();
133
134 // Filled in below to track the state of the young gen after the collection.
135 bool eden_empty;
136 bool survivors_empty;
137 bool young_gen_empty;
138
139 {
140 HandleMark hm;
141 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
142 // This is useful for debugging but don't change the output the
143 // the customer sees.
144 const char* gc_cause_str = "Full GC";
145 if (is_system_gc && PrintGCDetails) {
146 gc_cause_str = "Full GC (System)";
147 }
148 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
149 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
150 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
151 TraceCollectorStats tcs(counters());
152 TraceMemoryManagerStats tms(true /* Full GC */);
153
154 if (TraceGen1Time) accumulated_time()->start();
155
156 // Let the size policy know we're starting
157 size_policy->major_collection_begin();
158
159 // When collecting the permanent generation methodOops may be moving,
160 // so we either have to flush all bcp data or convert it into bci.
161 CodeCache::gc_prologue();
162 Threads::gc_prologue();
163 BiasedLocking::preserve_marks();
164
165 // Capture heap size before collection for printing.
166 size_t prev_used = heap->used();
167
168 // Capture perm gen size before collection for sizing.
169 size_t perm_gen_prev_used = perm_gen->used_in_bytes();
170
171 // For PrintGCDetails
172 size_t old_gen_prev_used = old_gen->used_in_bytes();
173 size_t young_gen_prev_used = young_gen->used_in_bytes();
174
175 allocate_stacks();
176
177 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
178 COMPILER2_PRESENT(DerivedPointerTable::clear());
179
180 ref_processor()->enable_discovery();
181 ref_processor()->setup_policy(clear_all_softrefs);
182
183 mark_sweep_phase1(clear_all_softrefs);
184
185 mark_sweep_phase2();
186
187 // Don't add any more derived pointers during phase3
188 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
189 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
190
191 mark_sweep_phase3();
192
193 mark_sweep_phase4();
194
195 restore_marks();
196
197 deallocate_stacks();
198
199 if (ZapUnusedHeapArea) {
200 // Do a complete mangle (top to end) because the usage for
201 // scratch does not maintain a top pointer.
202 young_gen->to_space()->mangle_unused_area_complete();
203 }
204
205 eden_empty = young_gen->eden_space()->is_empty();
206 if (!eden_empty) {
207 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
208 }
209
210 // Update heap occupancy information which is used as
211 // input to soft ref clearing policy at the next gc.
212 Universe::update_heap_info_at_gc();
213
214 survivors_empty = young_gen->from_space()->is_empty() &&
215 young_gen->to_space()->is_empty();
216 young_gen_empty = eden_empty && survivors_empty;
217
218 BarrierSet* bs = heap->barrier_set();
219 if (bs->is_a(BarrierSet::ModRef)) {
220 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
221 MemRegion old_mr = heap->old_gen()->reserved();
222 MemRegion perm_mr = heap->perm_gen()->reserved();
223 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
224
225 if (young_gen_empty) {
226 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
227 } else {
228 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
229 }
230 }
231
232 BiasedLocking::restore_marks();
233 Threads::gc_epilogue();
234 CodeCache::gc_epilogue();
235
236 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
237
238 ref_processor()->enqueue_discovered_references(NULL);
239
240 // Update time of last GC
241 reset_millis_since_last_gc();
242
243 // Let the size policy know we're done
244 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
245
246 if (UseAdaptiveSizePolicy) {
247
248 if (PrintAdaptiveSizePolicy) {
249 gclog_or_tty->print("AdaptiveSizeStart: ");
250 gclog_or_tty->stamp();
251 gclog_or_tty->print_cr(" collection: %d ",
252 heap->total_collections());
253 if (Verbose) {
254 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
255 " perm_gen_capacity: %d ",
256 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
257 perm_gen->capacity_in_bytes());
258 }
259 }
260
261 // Don't check if the size_policy is ready here. Let
262 // the size_policy check that internally.
263 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
264 ((gc_cause != GCCause::_java_lang_system_gc) ||
265 UseAdaptiveSizePolicyWithSystemGC)) {
266 // Calculate optimal free space amounts
267 assert(young_gen->max_size() >
268 young_gen->from_space()->capacity_in_bytes() +
269 young_gen->to_space()->capacity_in_bytes(),
270 "Sizes of space in young gen are out-of-bounds");
271 size_t max_eden_size = young_gen->max_size() -
272 young_gen->from_space()->capacity_in_bytes() -
273 young_gen->to_space()->capacity_in_bytes();
274 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
275 young_gen->eden_space()->used_in_bytes(),
276 old_gen->used_in_bytes(),
277 perm_gen->used_in_bytes(),
278 young_gen->eden_space()->capacity_in_bytes(),
279 old_gen->max_gen_size(),
280 max_eden_size,
281 true /* full gc*/,
282 gc_cause,
283 heap->collector_policy());
284
285 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
286
287 // Don't resize the young generation at an major collection. A
288 // desired young generation size may have been calculated but
289 // resizing the young generation complicates the code because the
290 // resizing of the old generation may have moved the boundary
291 // between the young generation and the old generation. Let the
292 // young generation resizing happen at the minor collections.
293 }
294 if (PrintAdaptiveSizePolicy) {
295 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
296 heap->total_collections());
297 }
298 }
299
300 if (UsePerfData) {
301 heap->gc_policy_counters()->update_counters();
302 heap->gc_policy_counters()->update_old_capacity(
303 old_gen->capacity_in_bytes());
304 heap->gc_policy_counters()->update_young_capacity(
305 young_gen->capacity_in_bytes());
306 }
307
308 heap->resize_all_tlabs();
309
310 // We collected the perm gen, so we'll resize it here.
311 perm_gen->compute_new_size(perm_gen_prev_used);
312
313 if (TraceGen1Time) accumulated_time()->stop();
314
315 if (PrintGC) {
316 if (PrintGCDetails) {
317 // Don't print a GC timestamp here. This is after the GC so
318 // would be confusing.
319 young_gen->print_used_change(young_gen_prev_used);
320 old_gen->print_used_change(old_gen_prev_used);
321 }
322 heap->print_heap_change(prev_used);
323 // Do perm gen after heap becase prev_used does
324 // not include the perm gen (done this way in the other
325 // collectors).
326 if (PrintGCDetails) {
327 perm_gen->print_used_change(perm_gen_prev_used);
328 }
329 }
330
331 // Track memory usage and detect low memory
332 MemoryService::track_memory_usage();
333 heap->update_counters();
334 }
335
336 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
337 HandleMark hm; // Discard invalid handles created during verification
338 gclog_or_tty->print(" VerifyAfterGC:");
339 Universe::verify(false);
340 }
341
342 // Re-verify object start arrays
343 if (VerifyObjectStartArray &&
344 VerifyAfterGC) {
345 old_gen->verify_object_start_array();
346 perm_gen->verify_object_start_array();
347 }
348
349 if (ZapUnusedHeapArea) {
350 old_gen->object_space()->check_mangled_unused_area_complete();
351 perm_gen->object_space()->check_mangled_unused_area_complete();
352 }
353
354 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
355
356 if (PrintHeapAtGC) {
357 Universe::print_heap_after_gc();
358 }
359
360 heap->post_full_gc_dump();
361
362 #ifdef TRACESPINNING
363 ParallelTaskTerminator::print_termination_counts();
364 #endif
365 }
366
367 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
368 PSYoungGen* young_gen,
369 PSOldGen* old_gen) {
370 MutableSpace* const eden_space = young_gen->eden_space();
371 assert(!eden_space->is_empty(), "eden must be non-empty");
372 assert(young_gen->virtual_space()->alignment() ==
373 old_gen->virtual_space()->alignment(), "alignments do not match");
374
375 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
376 return false;
377 }
378
379 // Both generations must be completely committed.
380 if (young_gen->virtual_space()->uncommitted_size() != 0) {
381 return false;
382 }
383 if (old_gen->virtual_space()->uncommitted_size() != 0) {
384 return false;
385 }
386
387 // Figure out how much to take from eden. Include the average amount promoted
388 // in the total; otherwise the next young gen GC will simply bail out to a
389 // full GC.
390 const size_t alignment = old_gen->virtual_space()->alignment();
391 const size_t eden_used = eden_space->used_in_bytes();
392 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
393 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
394 const size_t eden_capacity = eden_space->capacity_in_bytes();
395
396 if (absorb_size >= eden_capacity) {
397 return false; // Must leave some space in eden.
398 }
399
400 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
401 if (new_young_size < young_gen->min_gen_size()) {
402 return false; // Respect young gen minimum size.
403 }
404
405 if (TraceAdaptiveGCBoundary && Verbose) {
406 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
407 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
408 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
409 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
410 absorb_size / K,
411 eden_capacity / K, (eden_capacity - absorb_size) / K,
412 young_gen->from_space()->used_in_bytes() / K,
413 young_gen->to_space()->used_in_bytes() / K,
414 young_gen->capacity_in_bytes() / K, new_young_size / K);
415 }
416
417 // Fill the unused part of the old gen.
418 MutableSpace* const old_space = old_gen->object_space();
419 HeapWord* const unused_start = old_space->top();
420 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
421
422 if (unused_words > 0) {
423 if (unused_words < CollectedHeap::min_fill_size()) {
424 return false; // If the old gen cannot be filled, must give up.
425 }
426 CollectedHeap::fill_with_objects(unused_start, unused_words);
427 }
428
429 // Take the live data from eden and set both top and end in the old gen to
430 // eden top. (Need to set end because reset_after_change() mangles the region
431 // from end to virtual_space->high() in debug builds).
432 HeapWord* const new_top = eden_space->top();
433 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
434 absorb_size);
435 young_gen->reset_after_change();
436 old_space->set_top(new_top);
437 old_space->set_end(new_top);
438 old_gen->reset_after_change();
439
440 // Update the object start array for the filler object and the data from eden.
441 ObjectStartArray* const start_array = old_gen->start_array();
442 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
443 start_array->allocate_block(p);
444 }
445
446 // Could update the promoted average here, but it is not typically updated at
447 // full GCs and the value to use is unclear. Something like
448 //
449 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
450
451 size_policy->set_bytes_absorbed_from_eden(absorb_size);
452 return true;
453 }
454
455 void PSMarkSweep::allocate_stacks() {
456 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
457 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
458
459 PSYoungGen* young_gen = heap->young_gen();
460
461 MutableSpace* to_space = young_gen->to_space();
462 _preserved_marks = (PreservedMark*)to_space->top();
463 _preserved_count = 0;
464
465 // We want to calculate the size in bytes first.
466 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
467 // Now divide by the size of a PreservedMark
468 _preserved_count_max /= sizeof(PreservedMark);
469
470 _preserved_mark_stack = NULL;
471 _preserved_oop_stack = NULL;
472
473 _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
474 _objarray_stack = new (ResourceObj::C_HEAP) GrowableArray<ObjArrayTask>(50, true);
475
476 int size = SystemDictionary::number_of_classes() * 2;
477 _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
478 // (#klass/k)^2, for k ~ 10 appears a better setting, but this will have to do for
479 // now until we investigate a more optimal setting.
480 _revisit_mdo_stack = new (ResourceObj::C_HEAP) GrowableArray<DataLayout*>(size*2, true);
481 }
482
483
484 void PSMarkSweep::deallocate_stacks() {
485 if (_preserved_oop_stack) {
486 delete _preserved_mark_stack;
487 _preserved_mark_stack = NULL;
488 delete _preserved_oop_stack;
489 _preserved_oop_stack = NULL;
490 }
491
492 delete _marking_stack;
493 delete _objarray_stack;
494 delete _revisit_klass_stack;
495 delete _revisit_mdo_stack;
496 }
497
498 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
499 // Recursively traverse all live objects and mark them
500 EventMark m("1 mark object");
501 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty);
502 trace(" 1");
503
504 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
505 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
506
507 // General strong roots.
508 {
509 ParallelScavengeHeap::ParStrongRootsScope psrs;
510 Universe::oops_do(mark_and_push_closure());
511 ReferenceProcessor::oops_do(mark_and_push_closure());
512 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
513 CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
514 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
515 ObjectSynchronizer::oops_do(mark_and_push_closure());
516 FlatProfiler::oops_do(mark_and_push_closure());
517 Management::oops_do(mark_and_push_closure());
518 JvmtiExport::oops_do(mark_and_push_closure());
519 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
520 vmSymbols::oops_do(mark_and_push_closure());
521 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
522 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
523 }
524
525 // Flush marking stack.
526 follow_stack();
527
528 // Process reference objects found during marking
529 {
530 ref_processor()->setup_policy(clear_all_softrefs);
531 ref_processor()->process_discovered_references(
532 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL);
533 }
534
535 // Follow system dictionary roots and unload classes
536 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
537
538 // Follow code cache roots
539 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(),
540 purged_class);
541 follow_stack(); // Flush marking stack
542
543 // Update subklass/sibling/implementor links of live klasses
544 follow_weak_klass_links();
545 assert(_marking_stack->is_empty(), "just drained");
546
547 // Visit memoized mdo's and clear unmarked weak refs
548 follow_mdo_weak_refs();
549 assert(_marking_stack->is_empty(), "just drained");
550
551 // Visit symbol and interned string tables and delete unmarked oops
552 SymbolTable::unlink(is_alive_closure());
553 StringTable::unlink(is_alive_closure());
554
555 assert(_marking_stack->is_empty(), "stack should be empty by now");
556 }
557
558
559 void PSMarkSweep::mark_sweep_phase2() {
560 EventMark m("2 compute new addresses");
561 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty);
562 trace("2");
563
564 // Now all live objects are marked, compute the new object addresses.
565
566 // It is imperative that we traverse perm_gen LAST. If dead space is
567 // allowed a range of dead object may get overwritten by a dead int
568 // array. If perm_gen is not traversed last a klassOop may get
569 // overwritten. This is fine since it is dead, but if the class has dead
570 // instances we have to skip them, and in order to find their size we
571 // need the klassOop!
572 //
573 // It is not required that we traverse spaces in the same order in
574 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
575 // tracking expects us to do so. See comment under phase4.
576
577 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
578 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
579
580 PSOldGen* old_gen = heap->old_gen();
581 PSPermGen* perm_gen = heap->perm_gen();
582
583 // Begin compacting into the old gen
584 PSMarkSweepDecorator::set_destination_decorator_tenured();
585
586 // This will also compact the young gen spaces.
587 old_gen->precompact();
588
589 // Compact the perm gen into the perm gen
590 PSMarkSweepDecorator::set_destination_decorator_perm_gen();
591
592 perm_gen->precompact();
593 }
594
595 // This should be moved to the shared markSweep code!
596 class PSAlwaysTrueClosure: public BoolObjectClosure {
597 public:
598 void do_object(oop p) { ShouldNotReachHere(); }
599 bool do_object_b(oop p) { return true; }
600 };
601 static PSAlwaysTrueClosure always_true;
602
603 void PSMarkSweep::mark_sweep_phase3() {
604 // Adjust the pointers to reflect the new locations
605 EventMark m("3 adjust pointers");
606 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty);
607 trace("3");
608
609 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
610 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
611
612 PSYoungGen* young_gen = heap->young_gen();
613 PSOldGen* old_gen = heap->old_gen();
614 PSPermGen* perm_gen = heap->perm_gen();
615
616 // General strong roots.
617 Universe::oops_do(adjust_root_pointer_closure());
618 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
619 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
620 Threads::oops_do(adjust_root_pointer_closure(), NULL);
621 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
622 FlatProfiler::oops_do(adjust_root_pointer_closure());
623 Management::oops_do(adjust_root_pointer_closure());
624 JvmtiExport::oops_do(adjust_root_pointer_closure());
625 // SO_AllClasses
626 SystemDictionary::oops_do(adjust_root_pointer_closure());
627 vmSymbols::oops_do(adjust_root_pointer_closure());
628 //CodeCache::scavenge_root_nmethods_oops_do(adjust_root_pointer_closure());
629
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_root_pointer_closure());
634
635 CodeCache::oops_do(adjust_pointer_closure());
636 SymbolTable::oops_do(adjust_root_pointer_closure());
637 StringTable::oops_do(adjust_root_pointer_closure());
638 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
639 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure());
640
641 adjust_marks();
642
643 young_gen->adjust_pointers();
644 old_gen->adjust_pointers();
645 perm_gen->adjust_pointers();
646 }
647
648 void PSMarkSweep::mark_sweep_phase4() {
649 EventMark m("4 compact heap");
650 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty);
651 trace("4");
652
653 // All pointers are now adjusted, move objects accordingly
654
655 // It is imperative that we traverse perm_gen first in phase4. All
656 // classes must be allocated earlier than their instances, and traversing
657 // perm_gen first makes sure that all klassOops have moved to their new
658 // location before any instance does a dispatch through it's klass!
659 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
660 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
661
662 PSYoungGen* young_gen = heap->young_gen();
663 PSOldGen* old_gen = heap->old_gen();
664 PSPermGen* perm_gen = heap->perm_gen();
665
666 perm_gen->compact();
667 old_gen->compact();
668 young_gen->compact();
669 }
670
671 jlong PSMarkSweep::millis_since_last_gc() {
672 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
673 // XXX See note in genCollectedHeap::millis_since_last_gc().
674 if (ret_val < 0) {
675 NOT_PRODUCT(warning("time warp: %d", ret_val);)
676 return 0;
677 }
678 return ret_val;
679 }
680
681 void PSMarkSweep::reset_millis_since_last_gc() {
682 _time_of_last_gc = os::javaTimeMillis();
683 }