1 /*
2 * Copyright (c) 2001, 2012, 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/generationSizer.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/psPermGen.hpp"
36 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
37 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
38 #include "gc_implementation/shared/gcHeapSummary.hpp"
39 #include "gc_implementation/shared/gcTimer.hpp"
40 #include "gc_implementation/shared/gcTrace.hpp"
41 #include "gc_implementation/shared/gcTraceTime.hpp"
42 #include "gc_implementation/shared/isGCActiveMark.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 elapsedTimer PSMarkSweep::_accumulated_time;
59 unsigned int PSMarkSweep::_total_invocations = 0;
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 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount;
101 IntFlagSetting 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(os::elapsed_counter());
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 PSPermGen* perm_gen = heap->perm_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 gclog_or_tty->print(" VerifyBeforeGC:");
153 Universe::verify();
154 }
155
156 // Verify object start arrays
157 if (VerifyObjectStartArray &&
158 VerifyBeforeGC) {
159 old_gen->verify_object_start_array();
160 perm_gen->verify_object_start_array();
161 }
162
163 heap->pre_full_gc_dump(_gc_timer);
164
165 // Filled in below to track the state of the young gen after the collection.
166 bool eden_empty;
167 bool survivors_empty;
168 bool young_gen_empty;
169
170 {
171 HandleMark hm;
172
173 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
174 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
175 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
176 TraceCollectorStats tcs(counters());
177 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
178
179 if (TraceGen1Time) accumulated_time()->start();
180
181 // Let the size policy know we're starting
182 size_policy->major_collection_begin();
183
184 // When collecting the permanent generation methodOops may be moving,
185 // so we either have to flush all bcp data or convert it into bci.
186 CodeCache::gc_prologue();
187 Threads::gc_prologue();
188 BiasedLocking::preserve_marks();
189
190 // Capture heap size before collection for printing.
191 size_t prev_used = heap->used();
192
193 // Capture perm gen size before collection for sizing.
194 size_t perm_gen_prev_used = perm_gen->used_in_bytes();
195
196 // For PrintGCDetails
197 size_t old_gen_prev_used = old_gen->used_in_bytes();
198 size_t young_gen_prev_used = young_gen->used_in_bytes();
199
200 allocate_stacks();
201
202 COMPILER2_PRESENT(DerivedPointerTable::clear());
203
204 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
205 ref_processor()->setup_policy(clear_all_softrefs);
206
207 mark_sweep_phase1(clear_all_softrefs);
208
209 mark_sweep_phase2();
210
211 // Don't add any more derived pointers during phase3
212 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
213 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
214
215 mark_sweep_phase3();
216
217 mark_sweep_phase4();
218
219 restore_marks();
220
221 deallocate_stacks();
222
223 if (ZapUnusedHeapArea) {
224 // Do a complete mangle (top to end) because the usage for
225 // scratch does not maintain a top pointer.
226 young_gen->to_space()->mangle_unused_area_complete();
227 }
228
229 eden_empty = young_gen->eden_space()->is_empty();
230 if (!eden_empty) {
231 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
232 }
233
234 // Update heap occupancy information which is used as
235 // input to soft ref clearing policy at the next gc.
236 Universe::update_heap_info_at_gc();
237
238 survivors_empty = young_gen->from_space()->is_empty() &&
239 young_gen->to_space()->is_empty();
240 young_gen_empty = eden_empty && survivors_empty;
241
242 BarrierSet* bs = heap->barrier_set();
243 if (bs->is_a(BarrierSet::ModRef)) {
244 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
245 MemRegion old_mr = heap->old_gen()->reserved();
246 MemRegion perm_mr = heap->perm_gen()->reserved();
247 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
248
249 if (young_gen_empty) {
250 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
251 } else {
252 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
253 }
254 }
255
256 BiasedLocking::restore_marks();
257 Threads::gc_epilogue();
258 CodeCache::gc_epilogue();
259 JvmtiExport::gc_epilogue();
260
261 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
262
263 ref_processor()->enqueue_discovered_references(NULL);
264
265 // Update time of last GC
266 reset_millis_since_last_gc();
267
268 // Let the size policy know we're done
269 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
270
271 if (UseAdaptiveSizePolicy) {
272
273 if (PrintAdaptiveSizePolicy) {
274 gclog_or_tty->print("AdaptiveSizeStart: ");
275 gclog_or_tty->stamp();
276 gclog_or_tty->print_cr(" collection: %d ",
277 heap->total_collections());
278 if (Verbose) {
279 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
280 " perm_gen_capacity: %d ",
281 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
282 perm_gen->capacity_in_bytes());
283 }
284 }
285
286 // Don't check if the size_policy is ready here. Let
287 // the size_policy check that internally.
288 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
289 ((gc_cause != GCCause::_java_lang_system_gc) ||
290 UseAdaptiveSizePolicyWithSystemGC)) {
291 // Calculate optimal free space amounts
292 assert(young_gen->max_size() >
293 young_gen->from_space()->capacity_in_bytes() +
294 young_gen->to_space()->capacity_in_bytes(),
295 "Sizes of space in young gen are out-of-bounds");
296 size_t max_eden_size = young_gen->max_size() -
297 young_gen->from_space()->capacity_in_bytes() -
298 young_gen->to_space()->capacity_in_bytes();
299 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
300 young_gen->eden_space()->used_in_bytes(),
301 old_gen->used_in_bytes(),
302 perm_gen->used_in_bytes(),
303 young_gen->eden_space()->capacity_in_bytes(),
304 old_gen->max_gen_size(),
305 max_eden_size,
306 true /* full gc*/,
307 gc_cause,
308 heap->collector_policy());
309
310 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
311
312 // Don't resize the young generation at an major collection. A
313 // desired young generation size may have been calculated but
314 // resizing the young generation complicates the code because the
315 // resizing of the old generation may have moved the boundary
316 // between the young generation and the old generation. Let the
317 // young generation resizing happen at the minor collections.
318 }
319 if (PrintAdaptiveSizePolicy) {
320 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
321 heap->total_collections());
322 }
323 }
324
325 if (UsePerfData) {
326 heap->gc_policy_counters()->update_counters();
327 heap->gc_policy_counters()->update_old_capacity(
328 old_gen->capacity_in_bytes());
329 heap->gc_policy_counters()->update_young_capacity(
330 young_gen->capacity_in_bytes());
331 }
332
333 heap->resize_all_tlabs();
334
335 // We collected the perm gen, so we'll resize it here.
336 perm_gen->compute_new_size(perm_gen_prev_used);
337
338 if (TraceGen1Time) accumulated_time()->stop();
339
340 if (PrintGC) {
341 if (PrintGCDetails) {
342 // Don't print a GC timestamp here. This is after the GC so
343 // would be confusing.
344 young_gen->print_used_change(young_gen_prev_used);
345 old_gen->print_used_change(old_gen_prev_used);
346 }
347 heap->print_heap_change(prev_used);
348 // Do perm gen after heap becase prev_used does
349 // not include the perm gen (done this way in the other
350 // collectors).
351 if (PrintGCDetails) {
352 perm_gen->print_used_change(perm_gen_prev_used);
353 }
354 }
355
356 // Track memory usage and detect low memory
357 MemoryService::track_memory_usage();
358 heap->update_counters();
359 }
360
361 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
362 HandleMark hm; // Discard invalid handles created during verification
363 gclog_or_tty->print(" VerifyAfterGC:");
364 Universe::verify();
365 }
366
367 // Re-verify object start arrays
368 if (VerifyObjectStartArray &&
369 VerifyAfterGC) {
370 old_gen->verify_object_start_array();
371 perm_gen->verify_object_start_array();
372 }
373
374 if (ZapUnusedHeapArea) {
375 old_gen->object_space()->check_mangled_unused_area_complete();
376 perm_gen->object_space()->check_mangled_unused_area_complete();
377 }
378
379 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
380
381 heap->print_heap_after_gc();
382 heap->trace_heap_after_gc(_gc_tracer);
383
384 heap->post_full_gc_dump(_gc_timer);
385
386 #ifdef TRACESPINNING
387 ParallelTaskTerminator::print_termination_counts();
388 #endif
389
390 _gc_timer->register_gc_end(os::elapsed_counter());
391
392 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
393
394 return true;
395 }
396
397 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
398 PSYoungGen* young_gen,
399 PSOldGen* old_gen) {
400 MutableSpace* const eden_space = young_gen->eden_space();
401 assert(!eden_space->is_empty(), "eden must be non-empty");
402 assert(young_gen->virtual_space()->alignment() ==
403 old_gen->virtual_space()->alignment(), "alignments do not match");
404
405 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
406 return false;
407 }
408
409 // Both generations must be completely committed.
410 if (young_gen->virtual_space()->uncommitted_size() != 0) {
411 return false;
412 }
413 if (old_gen->virtual_space()->uncommitted_size() != 0) {
414 return false;
415 }
416
417 // Figure out how much to take from eden. Include the average amount promoted
418 // in the total; otherwise the next young gen GC will simply bail out to a
419 // full GC.
420 const size_t alignment = old_gen->virtual_space()->alignment();
421 const size_t eden_used = eden_space->used_in_bytes();
422 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
423 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
424 const size_t eden_capacity = eden_space->capacity_in_bytes();
425
426 if (absorb_size >= eden_capacity) {
427 return false; // Must leave some space in eden.
428 }
429
430 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
431 if (new_young_size < young_gen->min_gen_size()) {
432 return false; // Respect young gen minimum size.
433 }
434
435 if (TraceAdaptiveGCBoundary && Verbose) {
436 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
437 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
438 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
439 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
440 absorb_size / K,
441 eden_capacity / K, (eden_capacity - absorb_size) / K,
442 young_gen->from_space()->used_in_bytes() / K,
443 young_gen->to_space()->used_in_bytes() / K,
444 young_gen->capacity_in_bytes() / K, new_young_size / K);
445 }
446
447 // Fill the unused part of the old gen.
448 MutableSpace* const old_space = old_gen->object_space();
449 HeapWord* const unused_start = old_space->top();
450 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
451
452 if (unused_words > 0) {
453 if (unused_words < CollectedHeap::min_fill_size()) {
454 return false; // If the old gen cannot be filled, must give up.
455 }
456 CollectedHeap::fill_with_objects(unused_start, unused_words);
457 }
458
459 // Take the live data from eden and set both top and end in the old gen to
460 // eden top. (Need to set end because reset_after_change() mangles the region
461 // from end to virtual_space->high() in debug builds).
462 HeapWord* const new_top = eden_space->top();
463 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
464 absorb_size);
465 young_gen->reset_after_change();
466 old_space->set_top(new_top);
467 old_space->set_end(new_top);
468 old_gen->reset_after_change();
469
470 // Update the object start array for the filler object and the data from eden.
471 ObjectStartArray* const start_array = old_gen->start_array();
472 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
473 start_array->allocate_block(p);
474 }
475
476 // Could update the promoted average here, but it is not typically updated at
477 // full GCs and the value to use is unclear. Something like
478 //
479 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
480
481 size_policy->set_bytes_absorbed_from_eden(absorb_size);
482 return true;
483 }
484
485 void PSMarkSweep::allocate_stacks() {
486 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
487 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
488
489 PSYoungGen* young_gen = heap->young_gen();
490
491 MutableSpace* to_space = young_gen->to_space();
492 _preserved_marks = (PreservedMark*)to_space->top();
493 _preserved_count = 0;
494
495 // We want to calculate the size in bytes first.
496 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
497 // Now divide by the size of a PreservedMark
498 _preserved_count_max /= sizeof(PreservedMark);
499 }
500
501
502 void PSMarkSweep::deallocate_stacks() {
503 _preserved_mark_stack.clear(true);
504 _preserved_oop_stack.clear(true);
505 _marking_stack.clear();
506 _objarray_stack.clear(true);
507 _revisit_klass_stack.clear(true);
508 _revisit_mdo_stack.clear(true);
509 }
510
511 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
512 // Recursively traverse all live objects and mark them
513 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer);
514 trace(" 1");
515
516 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
517 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
518
519 // General strong roots.
520 {
521 ParallelScavengeHeap::ParStrongRootsScope psrs;
522 Universe::oops_do(mark_and_push_closure());
523 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
524 CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
525 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
526 ObjectSynchronizer::oops_do(mark_and_push_closure());
527 FlatProfiler::oops_do(mark_and_push_closure());
528 Management::oops_do(mark_and_push_closure());
529 JvmtiExport::oops_do(mark_and_push_closure());
530 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
531 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
532 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
533 }
534
535 // Flush marking stack.
536 follow_stack();
537
538 // Process reference objects found during marking
539 {
540 ref_processor()->setup_policy(clear_all_softrefs);
541 const ReferenceProcessorStats& stats =
542 ref_processor()->process_discovered_references(
543 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer);
544 gc_tracer()->report_gc_reference_stats(stats);
545 }
546
547 // Follow system dictionary roots and unload classes
548 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
549
550 // Follow code cache roots
551 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(),
552 purged_class);
553 follow_stack(); // Flush marking stack
554
555 // Update subklass/sibling/implementor links of live klasses
556 follow_weak_klass_links();
557 assert(_marking_stack.is_empty(), "just drained");
558
559 // Visit memoized mdo's and clear unmarked weak refs
560 follow_mdo_weak_refs();
561 assert(_marking_stack.is_empty(), "just drained");
562
563 // Visit interned string tables and delete unmarked oops
564 StringTable::unlink(is_alive_closure());
565 // Clean up unreferenced symbols in symbol table.
566 SymbolTable::unlink();
567
568 assert(_marking_stack.is_empty(), "stack should be empty by now");
569 }
570
571
572 void PSMarkSweep::mark_sweep_phase2() {
573 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer);
574 trace("2");
575
576 // Now all live objects are marked, compute the new object addresses.
577
578 // It is imperative that we traverse perm_gen LAST. If dead space is
579 // allowed a range of dead object may get overwritten by a dead int
580 // array. If perm_gen is not traversed last a klassOop may get
581 // overwritten. This is fine since it is dead, but if the class has dead
582 // instances we have to skip them, and in order to find their size we
583 // need the klassOop!
584 //
585 // It is not required that we traverse spaces in the same order in
586 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
587 // tracking expects us to do so. See comment under phase4.
588
589 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
590 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
591
592 PSOldGen* old_gen = heap->old_gen();
593 PSPermGen* perm_gen = heap->perm_gen();
594
595 // Begin compacting into the old gen
596 PSMarkSweepDecorator::set_destination_decorator_tenured();
597
598 // This will also compact the young gen spaces.
599 old_gen->precompact();
600
601 // Compact the perm gen into the perm gen
602 PSMarkSweepDecorator::set_destination_decorator_perm_gen();
603
604 perm_gen->precompact();
605 }
606
607 // This should be moved to the shared markSweep code!
608 class PSAlwaysTrueClosure: public BoolObjectClosure {
609 public:
610 void do_object(oop p) { ShouldNotReachHere(); }
611 bool do_object_b(oop p) { return true; }
612 };
613 static PSAlwaysTrueClosure always_true;
614
615 void PSMarkSweep::mark_sweep_phase3() {
616 // Adjust the pointers to reflect the new locations
617 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer);
618 trace("3");
619
620 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
621 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
622
623 PSYoungGen* young_gen = heap->young_gen();
624 PSOldGen* old_gen = heap->old_gen();
625 PSPermGen* perm_gen = heap->perm_gen();
626
627 // General strong roots.
628 Universe::oops_do(adjust_root_pointer_closure());
629 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
630 Threads::oops_do(adjust_root_pointer_closure(), NULL);
631 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
632 FlatProfiler::oops_do(adjust_root_pointer_closure());
633 Management::oops_do(adjust_root_pointer_closure());
634 JvmtiExport::oops_do(adjust_root_pointer_closure());
635 // SO_AllClasses
636 SystemDictionary::oops_do(adjust_root_pointer_closure());
637 //CodeCache::scavenge_root_nmethods_oops_do(adjust_root_pointer_closure());
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_root_pointer_closure());
643
644 CodeCache::oops_do(adjust_pointer_closure());
645 StringTable::oops_do(adjust_root_pointer_closure());
646 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
647 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure());
648
649 adjust_marks();
650
651 young_gen->adjust_pointers();
652 old_gen->adjust_pointers();
653 perm_gen->adjust_pointers();
654 }
655
656 void PSMarkSweep::mark_sweep_phase4() {
657 EventMark m("4 compact heap");
658 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer);
659 trace("4");
660
661 // All pointers are now adjusted, move objects accordingly
662
663 // It is imperative that we traverse perm_gen first in phase4. All
664 // classes must be allocated earlier than their instances, and traversing
665 // perm_gen first makes sure that all klassOops have moved to their new
666 // location before any instance does a dispatch through it's klass!
667 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
668 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
669
670 PSYoungGen* young_gen = heap->young_gen();
671 PSOldGen* old_gen = heap->old_gen();
672 PSPermGen* perm_gen = heap->perm_gen();
673
674 perm_gen->compact();
675 old_gen->compact();
676 young_gen->compact();
677 }
678
679 jlong PSMarkSweep::millis_since_last_gc() {
680 // We need a monotonically non-deccreasing time in ms but
681 // os::javaTimeMillis() does not guarantee monotonicity.
682 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
683 jlong ret_val = now - _time_of_last_gc;
684 // XXX See note in genCollectedHeap::millis_since_last_gc().
685 if (ret_val < 0) {
686 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
687 return 0;
688 }
689 return ret_val;
690 }
691
692 void PSMarkSweep::reset_millis_since_last_gc() {
693 // We need a monotonically non-deccreasing time in ms but
694 // os::javaTimeMillis() does not guarantee monotonicity.
695 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
696 }