1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any 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 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
50 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
51 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
52 assert(!Universe::heap()->is_gc_active(), "not reentrant");
53
54 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
55 GCCause::Cause gc_cause = heap->gc_cause();
56 PSAdaptiveSizePolicy* policy = heap->size_policy();
57
58 // Before each allocation/collection attempt, find out from the
59 // policy object if GCs are, on the whole, taking too long. If so,
60 // bail out without attempting a collection. The exceptions are
61 // for explicitly requested GC's.
62 if (!policy->gc_time_limit_exceeded() ||
63 GCCause::is_user_requested_gc(gc_cause) ||
64 GCCause::is_serviceability_requested_gc(gc_cause)) {
65 IsGCActiveMark mark;
66
67 if (ScavengeBeforeFullGC) {
68 PSScavenge::invoke_no_policy();
69 }
70
71 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount;
72 IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
73 PSMarkSweep::invoke_no_policy(maximum_heap_compaction);
74 }
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 PSYoungGen* young_gen = heap->young_gen();
93 PSOldGen* old_gen = heap->old_gen();
94 PSPermGen* perm_gen = heap->perm_gen();
95
96 // Increment the invocation count
97 heap->increment_total_collections(true /* full */);
98
99 // Save information needed to minimize mangling
100 heap->record_gen_tops_before_GC();
101
102 // We need to track unique mark sweep invocations as well.
103 _total_invocations++;
104
105 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
106
107 if (PrintHeapAtGC) {
108 Universe::print_heap_before_gc();
109 }
110
111 // Fill in TLABs
112 heap->accumulate_statistics_all_tlabs();
113 heap->ensure_parsability(true); // retire TLABs
114
115 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
116 HandleMark hm; // Discard invalid handles created during verification
117 gclog_or_tty->print(" VerifyBeforeGC:");
118 Universe::verify(true);
119 }
120
121 // Verify object start arrays
122 if (VerifyObjectStartArray &&
123 VerifyBeforeGC) {
124 old_gen->verify_object_start_array();
125 perm_gen->verify_object_start_array();
126 }
127
128 heap->pre_full_gc_dump();
129
130 // Filled in below to track the state of the young gen after the collection.
131 bool eden_empty;
132 bool survivors_empty;
133 bool young_gen_empty;
134
135 {
136 HandleMark hm;
137 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
138 // This is useful for debugging but don't change the output the
139 // the customer sees.
140 const char* gc_cause_str = "Full GC";
141 if (is_system_gc && PrintGCDetails) {
142 gc_cause_str = "Full GC (System)";
143 }
144 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
145 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
146 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
147 TraceCollectorStats tcs(counters());
148 TraceMemoryManagerStats tms(true /* Full GC */);
149
150 if (TraceGen1Time) accumulated_time()->start();
151
152 // Let the size policy know we're starting
153 size_policy->major_collection_begin();
154
155 // When collecting the permanent generation methodOops may be moving,
156 // so we either have to flush all bcp data or convert it into bci.
157 CodeCache::gc_prologue();
158 Threads::gc_prologue();
159 BiasedLocking::preserve_marks();
160
161 // Capture heap size before collection for printing.
162 size_t prev_used = heap->used();
163
164 // Capture perm gen size before collection for sizing.
165 size_t perm_gen_prev_used = perm_gen->used_in_bytes();
166
167 // For PrintGCDetails
168 size_t old_gen_prev_used = old_gen->used_in_bytes();
169 size_t young_gen_prev_used = young_gen->used_in_bytes();
170
171 allocate_stacks();
172
173 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
174 COMPILER2_PRESENT(DerivedPointerTable::clear());
175
176 ref_processor()->enable_discovery();
177 ref_processor()->setup_policy(clear_all_softrefs);
178
179 mark_sweep_phase1(clear_all_softrefs);
180
181 mark_sweep_phase2();
182
183 // Don't add any more derived pointers during phase3
184 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
185 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
186
187 mark_sweep_phase3();
188
189 mark_sweep_phase4();
190
191 restore_marks();
192
193 deallocate_stacks();
194
195 if (ZapUnusedHeapArea) {
196 // Do a complete mangle (top to end) because the usage for
197 // scratch does not maintain a top pointer.
198 young_gen->to_space()->mangle_unused_area_complete();
199 }
200
201 eden_empty = young_gen->eden_space()->is_empty();
202 if (!eden_empty) {
203 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
204 }
205
206 // Update heap occupancy information which is used as
207 // input to soft ref clearing policy at the next gc.
208 Universe::update_heap_info_at_gc();
209
210 survivors_empty = young_gen->from_space()->is_empty() &&
211 young_gen->to_space()->is_empty();
212 young_gen_empty = eden_empty && survivors_empty;
213
214 BarrierSet* bs = heap->barrier_set();
215 if (bs->is_a(BarrierSet::ModRef)) {
216 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
217 MemRegion old_mr = heap->old_gen()->reserved();
218 MemRegion perm_mr = heap->perm_gen()->reserved();
219 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
220
221 if (young_gen_empty) {
222 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
223 } else {
224 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
225 }
226 }
227
228 BiasedLocking::restore_marks();
229 Threads::gc_epilogue();
230 CodeCache::gc_epilogue();
231
232 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
233
234 ref_processor()->enqueue_discovered_references(NULL);
235
236 // Update time of last GC
237 reset_millis_since_last_gc();
238
239 // Let the size policy know we're done
240 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
241
242 bool free_ratio_in_effect = false;
243 if ((UseFreeRatioForParallelGC ||
244 (UseFreeRatioOnlyInSystemGCForParallelGC &&
245 gc_cause == GCCause::_java_lang_system_gc))) {
246 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
247 free_ratio_in_effect = heap->try_to_shrink_by_free_ratio(true);
248 }
249
250 if (!free_ratio_in_effect && UseAdaptiveSizePolicy) {
251
252 if (PrintAdaptiveSizePolicy) {
253 gclog_or_tty->print("AdaptiveSizeStart: ");
254 gclog_or_tty->stamp();
255 gclog_or_tty->print_cr(" collection: %d ",
256 heap->total_collections());
257 if (Verbose) {
258 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
259 " perm_gen_capacity: %d ",
260 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
261 perm_gen->capacity_in_bytes());
262 }
263 }
264
265 // Don't check if the size_policy is ready here. Let
266 // the size_policy check that internally.
267 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
268 ((gc_cause != GCCause::_java_lang_system_gc) ||
269 UseAdaptiveSizePolicyWithSystemGC)) {
270 // Calculate optimal free space amounts
271 assert(young_gen->max_size() >
272 young_gen->from_space()->capacity_in_bytes() +
273 young_gen->to_space()->capacity_in_bytes(),
274 "Sizes of space in young gen are out-of-bounds");
275 size_t max_eden_size = young_gen->max_size() -
276 young_gen->from_space()->capacity_in_bytes() -
277 young_gen->to_space()->capacity_in_bytes();
278 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
279 young_gen->eden_space()->used_in_bytes(),
280 old_gen->used_in_bytes(),
281 perm_gen->used_in_bytes(),
282 young_gen->eden_space()->capacity_in_bytes(),
283 old_gen->max_gen_size(),
284 max_eden_size,
285 true /* full gc*/,
286 gc_cause);
287
288 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
289
290 // Don't resize the young generation at an major collection. A
291 // desired young generation size may have been calculated but
292 // resizing the young generation complicates the code because the
293 // resizing of the old generation may have moved the boundary
294 // between the young generation and the old generation. Let the
295 // young generation resizing happen at the minor collections.
296 }
297 if (PrintAdaptiveSizePolicy) {
298 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
299 heap->total_collections());
300 }
301 }
302
303 if (UsePerfData) {
304 heap->gc_policy_counters()->update_counters();
305 heap->gc_policy_counters()->update_old_capacity(
306 old_gen->capacity_in_bytes());
307 heap->gc_policy_counters()->update_young_capacity(
308 young_gen->capacity_in_bytes());
309 }
310
311 heap->resize_all_tlabs();
312
313 // We collected the perm gen, so we'll resize it here.
314 perm_gen->compute_new_size(perm_gen_prev_used);
315
316 if (TraceGen1Time) accumulated_time()->stop();
317
318 if (PrintGC) {
319 if (PrintGCDetails) {
320 // Don't print a GC timestamp here. This is after the GC so
321 // would be confusing.
322 young_gen->print_used_change(young_gen_prev_used);
323 old_gen->print_used_change(old_gen_prev_used);
324 }
325 heap->print_heap_change(prev_used);
326 // Do perm gen after heap becase prev_used does
327 // not include the perm gen (done this way in the other
328 // collectors).
329 if (PrintGCDetails) {
330 perm_gen->print_used_change(perm_gen_prev_used);
331 }
332 }
333
334 // Track memory usage and detect low memory
335 MemoryService::track_memory_usage();
336 heap->update_counters();
337
338 if (PrintGCDetails) {
339 if (size_policy->print_gc_time_limit_would_be_exceeded()) {
340 if (size_policy->gc_time_limit_exceeded()) {
341 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit "
342 "of %d%%", GCTimeLimit);
343 } else {
344 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit "
345 "of %d%%", GCTimeLimit);
346 }
347 }
348 size_policy->set_print_gc_time_limit_would_be_exceeded(false);
349 }
350 }
351
352 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
353 HandleMark hm; // Discard invalid handles created during verification
354 gclog_or_tty->print(" VerifyAfterGC:");
355 Universe::verify(false);
356 }
357
358 // Re-verify object start arrays
359 if (VerifyObjectStartArray &&
360 VerifyAfterGC) {
361 old_gen->verify_object_start_array();
362 perm_gen->verify_object_start_array();
363 }
364
365 if (ZapUnusedHeapArea) {
366 old_gen->object_space()->check_mangled_unused_area_complete();
367 perm_gen->object_space()->check_mangled_unused_area_complete();
368 }
369
370 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
371
372 if (PrintHeapAtGC) {
373 Universe::print_heap_after_gc();
374 }
375
376 heap->post_full_gc_dump();
377
378 #ifdef TRACESPINNING
379 ParallelTaskTerminator::print_termination_counts();
380 #endif
381 }
382
383 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
384 PSYoungGen* young_gen,
385 PSOldGen* old_gen) {
386 MutableSpace* const eden_space = young_gen->eden_space();
387 assert(!eden_space->is_empty(), "eden must be non-empty");
388 assert(young_gen->virtual_space()->alignment() ==
389 old_gen->virtual_space()->alignment(), "alignments do not match");
390
391 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
392 return false;
393 }
394
395 // Both generations must be completely committed.
396 if (young_gen->virtual_space()->uncommitted_size() != 0) {
397 return false;
398 }
399 if (old_gen->virtual_space()->uncommitted_size() != 0) {
400 return false;
401 }
402
403 // Figure out how much to take from eden. Include the average amount promoted
404 // in the total; otherwise the next young gen GC will simply bail out to a
405 // full GC.
406 const size_t alignment = old_gen->virtual_space()->alignment();
407 const size_t eden_used = eden_space->used_in_bytes();
408 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
409 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
410 const size_t eden_capacity = eden_space->capacity_in_bytes();
411
412 if (absorb_size >= eden_capacity) {
413 return false; // Must leave some space in eden.
414 }
415
416 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
417 if (new_young_size < young_gen->min_gen_size()) {
418 return false; // Respect young gen minimum size.
419 }
420
421 if (TraceAdaptiveGCBoundary && Verbose) {
422 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
423 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
424 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
425 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
426 absorb_size / K,
427 eden_capacity / K, (eden_capacity - absorb_size) / K,
428 young_gen->from_space()->used_in_bytes() / K,
429 young_gen->to_space()->used_in_bytes() / K,
430 young_gen->capacity_in_bytes() / K, new_young_size / K);
431 }
432
433 // Fill the unused part of the old gen.
434 MutableSpace* const old_space = old_gen->object_space();
435 HeapWord* const unused_start = old_space->top();
436 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
437
438 if (unused_words > 0) {
439 if (unused_words < CollectedHeap::min_fill_size()) {
440 return false; // If the old gen cannot be filled, must give up.
441 }
442 CollectedHeap::fill_with_objects(unused_start, unused_words);
443 }
444
445 // Take the live data from eden and set both top and end in the old gen to
446 // eden top. (Need to set end because reset_after_change() mangles the region
447 // from end to virtual_space->high() in debug builds).
448 HeapWord* const new_top = eden_space->top();
449 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
450 absorb_size);
451 young_gen->reset_after_change();
452 old_space->set_top(new_top);
453 old_space->set_end(new_top);
454 old_gen->reset_after_change();
455
456 // Update the object start array for the filler object and the data from eden.
457 ObjectStartArray* const start_array = old_gen->start_array();
458 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
459 start_array->allocate_block(p);
460 }
461
462 // Could update the promoted average here, but it is not typically updated at
463 // full GCs and the value to use is unclear. Something like
464 //
465 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
466
467 size_policy->set_bytes_absorbed_from_eden(absorb_size);
468 return true;
469 }
470
471 void PSMarkSweep::allocate_stacks() {
472 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
473 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
474
475 PSYoungGen* young_gen = heap->young_gen();
476
477 MutableSpace* to_space = young_gen->to_space();
478 _preserved_marks = (PreservedMark*)to_space->top();
479 _preserved_count = 0;
480
481 // We want to calculate the size in bytes first.
482 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
483 // Now divide by the size of a PreservedMark
484 _preserved_count_max /= sizeof(PreservedMark);
485
486 _preserved_mark_stack = NULL;
487 _preserved_oop_stack = NULL;
488
489 _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
490
491 int size = SystemDictionary::number_of_classes() * 2;
492 _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
493 // (#klass/k)^2, for k ~ 10 appears a better setting, but this will have to do for
494 // now until we investigate a more optimal setting.
495 _revisit_mdo_stack = new (ResourceObj::C_HEAP) GrowableArray<DataLayout*>(size*2, true);
496 }
497
498
499 void PSMarkSweep::deallocate_stacks() {
500 if (_preserved_oop_stack) {
501 delete _preserved_mark_stack;
502 _preserved_mark_stack = NULL;
503 delete _preserved_oop_stack;
504 _preserved_oop_stack = NULL;
505 }
506
507 delete _marking_stack;
508 delete _revisit_klass_stack;
509 delete _revisit_mdo_stack;
510 }
511
512 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
513 // Recursively traverse all live objects and mark them
514 EventMark m("1 mark object");
515 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty);
516 trace(" 1");
517
518 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
519 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
520
521 // General strong roots.
522 {
523 ParallelScavengeHeap::ParStrongRootsScope psrs;
524 Universe::oops_do(mark_and_push_closure());
525 ReferenceProcessor::oops_do(mark_and_push_closure());
526 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
527 CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
528 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
529 ObjectSynchronizer::oops_do(mark_and_push_closure());
530 FlatProfiler::oops_do(mark_and_push_closure());
531 Management::oops_do(mark_and_push_closure());
532 JvmtiExport::oops_do(mark_and_push_closure());
533 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
534 vmSymbols::oops_do(mark_and_push_closure());
535 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
536 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
537 }
538
539 // Flush marking stack.
540 follow_stack();
541
542 // Process reference objects found during marking
543 {
544 ref_processor()->setup_policy(clear_all_softrefs);
545 ref_processor()->process_discovered_references(
546 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL);
547 }
548
549 // Follow system dictionary roots and unload classes
550 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
551
552 // Follow code cache roots
553 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(),
554 purged_class);
555 follow_stack(); // Flush marking stack
556
557 // Update subklass/sibling/implementor links of live klasses
558 follow_weak_klass_links();
559 assert(_marking_stack->is_empty(), "just drained");
560
561 // Visit memoized mdo's and clear unmarked weak refs
562 follow_mdo_weak_refs();
563 assert(_marking_stack->is_empty(), "just drained");
564
565 // Visit symbol and interned string tables and delete unmarked oops
566 SymbolTable::unlink(is_alive_closure());
567 StringTable::unlink(is_alive_closure());
568
569 assert(_marking_stack->is_empty(), "stack should be empty by now");
570 }
571
572
573 void PSMarkSweep::mark_sweep_phase2() {
574 EventMark m("2 compute new addresses");
575 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty);
576 trace("2");
577
578 // Now all live objects are marked, compute the new object addresses.
579
580 // It is imperative that we traverse perm_gen LAST. If dead space is
581 // allowed a range of dead object may get overwritten by a dead int
582 // array. If perm_gen is not traversed last a klassOop may get
583 // overwritten. This is fine since it is dead, but if the class has dead
584 // instances we have to skip them, and in order to find their size we
585 // need the klassOop!
586 //
587 // It is not required that we traverse spaces in the same order in
588 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
589 // tracking expects us to do so. See comment under phase4.
590
591 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
592 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
593
594 PSOldGen* old_gen = heap->old_gen();
595 PSPermGen* perm_gen = heap->perm_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 // Compact the perm gen into the perm gen
604 PSMarkSweepDecorator::set_destination_decorator_perm_gen();
605
606 perm_gen->precompact();
607 }
608
609 // This should be moved to the shared markSweep code!
610 class PSAlwaysTrueClosure: public BoolObjectClosure {
611 public:
612 void do_object(oop p) { ShouldNotReachHere(); }
613 bool do_object_b(oop p) { return true; }
614 };
615 static PSAlwaysTrueClosure always_true;
616
617 void PSMarkSweep::mark_sweep_phase3() {
618 // Adjust the pointers to reflect the new locations
619 EventMark m("3 adjust pointers");
620 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty);
621 trace("3");
622
623 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
624 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
625
626 PSYoungGen* young_gen = heap->young_gen();
627 PSOldGen* old_gen = heap->old_gen();
628 PSPermGen* perm_gen = heap->perm_gen();
629
630 // General strong roots.
631 Universe::oops_do(adjust_root_pointer_closure());
632 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
633 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
634 Threads::oops_do(adjust_root_pointer_closure(), NULL);
635 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
636 FlatProfiler::oops_do(adjust_root_pointer_closure());
637 Management::oops_do(adjust_root_pointer_closure());
638 JvmtiExport::oops_do(adjust_root_pointer_closure());
639 // SO_AllClasses
640 SystemDictionary::oops_do(adjust_root_pointer_closure());
641 vmSymbols::oops_do(adjust_root_pointer_closure());
642 //CodeCache::scavenge_root_nmethods_oops_do(adjust_root_pointer_closure());
643
644 // Now adjust pointers in remaining weak roots. (All of which should
645 // have been cleared if they pointed to non-surviving objects.)
646 // Global (weak) JNI handles
647 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
648
649 CodeCache::oops_do(adjust_pointer_closure());
650 SymbolTable::oops_do(adjust_root_pointer_closure());
651 StringTable::oops_do(adjust_root_pointer_closure());
652 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
653 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure());
654
655 adjust_marks();
656
657 young_gen->adjust_pointers();
658 old_gen->adjust_pointers();
659 perm_gen->adjust_pointers();
660 }
661
662 void PSMarkSweep::mark_sweep_phase4() {
663 EventMark m("4 compact heap");
664 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty);
665 trace("4");
666
667 // All pointers are now adjusted, move objects accordingly
668
669 // It is imperative that we traverse perm_gen first in phase4. All
670 // classes must be allocated earlier than their instances, and traversing
671 // perm_gen first makes sure that all klassOops have moved to their new
672 // location before any instance does a dispatch through it's klass!
673 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
674 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
675
676 PSYoungGen* young_gen = heap->young_gen();
677 PSOldGen* old_gen = heap->old_gen();
678 PSPermGen* perm_gen = heap->perm_gen();
679
680 perm_gen->compact();
681 old_gen->compact();
682 young_gen->compact();
683 }
684
685 jlong PSMarkSweep::millis_since_last_gc() {
686 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
687 // XXX See note in genCollectedHeap::millis_since_last_gc().
688 if (ret_val < 0) {
689 NOT_PRODUCT(warning("time warp: %d", ret_val);)
690 return 0;
691 }
692 return ret_val;
693 }
694
695 void PSMarkSweep::reset_millis_since_last_gc() {
696 _time_of_last_gc = os::javaTimeMillis();
697 }