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/isGCActiveMark.hpp"
39 #include "gc_implementation/shared/spaceDecorator.hpp"
40 #include "gc_interface/gcCause.hpp"
41 #include "memory/gcLocker.inline.hpp"
42 #include "memory/referencePolicy.hpp"
43 #include "memory/referenceProcessor.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "runtime/biasedLocking.hpp"
46 #include "runtime/fprofiler.hpp"
47 #include "runtime/safepoint.hpp"
48 #include "runtime/vmThread.hpp"
49 #include "services/management.hpp"
50 #include "services/memoryService.hpp"
51 #include "utilities/events.hpp"
52 #include "utilities/stack.inline.hpp"
53
54 elapsedTimer PSMarkSweep::_accumulated_time;
55 unsigned int PSMarkSweep::_total_invocations = 0;
56 jlong PSMarkSweep::_time_of_last_gc = 0;
57 CollectorCounters* PSMarkSweep::_counters = NULL;
58
59 void PSMarkSweep::initialize() {
60 MemRegion mr = Universe::heap()->reserved_region();
61 _ref_processor = new ReferenceProcessor(mr); // a vanilla ref proc
62 _counters = new CollectorCounters("PSMarkSweep", 1);
63 }
64
65 // This method contains all heap specific policy for invoking mark sweep.
66 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
67 // the heap. It will do nothing further. If we need to bail out for policy
68 // reasons, scavenge before full gc, or any other specialized behavior, it
69 // needs to be added here.
70 //
71 // Note that this method should only be called from the vm_thread while
72 // at a safepoint!
73 //
74 // Note that the all_soft_refs_clear flag in the collector policy
75 // may be true because this method can be called without intervening
76 // activity. For example when the heap space is tight and full measure
77 // are being taken to free space.
78
79 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
80 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
81 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
82 assert(!Universe::heap()->is_gc_active(), "not reentrant");
83
84 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
85 GCCause::Cause gc_cause = heap->gc_cause();
86 PSAdaptiveSizePolicy* policy = heap->size_policy();
87 IsGCActiveMark mark;
88
89 if (ScavengeBeforeFullGC) {
90 PSScavenge::invoke_no_policy();
91 }
92
93 const bool clear_all_soft_refs =
94 heap->collector_policy()->should_clear_all_soft_refs();
95
96 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount;
97 IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
98 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
99 }
100
101 // This method contains no policy. You should probably
102 // be calling invoke() instead.
103 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
104 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
105 assert(ref_processor() != NULL, "Sanity");
106
107 if (GC_locker::check_active_before_gc()) {
108 return false;
109 }
110
111 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
112 GCCause::Cause gc_cause = heap->gc_cause();
113 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
114 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
115
116 // The scope of casr should end after code that can change
117 // CollectorPolicy::_should_clear_all_soft_refs.
118 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());
119
120 PSYoungGen* young_gen = heap->young_gen();
121 PSOldGen* old_gen = heap->old_gen();
122 PSPermGen* perm_gen = heap->perm_gen();
123
124 // Increment the invocation count
125 heap->increment_total_collections(true /* full */);
126
127 // Save information needed to minimize mangling
128 heap->record_gen_tops_before_GC();
129
130 // We need to track unique mark sweep invocations as well.
131 _total_invocations++;
132
133 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
134
135 heap->print_heap_before_gc();
136
137 // Fill in TLABs
138 heap->accumulate_statistics_all_tlabs();
139 heap->ensure_parsability(true); // retire TLABs
140
141 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
142 HandleMark hm; // Discard invalid handles created during verification
143 gclog_or_tty->print(" VerifyBeforeGC:");
144 Universe::verify(true);
145 }
146
147 // Verify object start arrays
148 if (VerifyObjectStartArray &&
149 VerifyBeforeGC) {
150 old_gen->verify_object_start_array();
151 perm_gen->verify_object_start_array();
152 }
153
154 heap->pre_full_gc_dump();
155
156 // Filled in below to track the state of the young gen after the collection.
157 bool eden_empty;
158 bool survivors_empty;
159 bool young_gen_empty;
160
161 {
162 HandleMark hm;
163
164 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
165 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
166 TraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty);
167 TraceCollectorStats tcs(counters());
168 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
169
170 if (TraceGen1Time) accumulated_time()->start();
171
172 // Let the size policy know we're starting
173 size_policy->major_collection_begin();
174
175 // When collecting the permanent generation methodOops may be moving,
176 // so we either have to flush all bcp data or convert it into bci.
177 CodeCache::gc_prologue();
178 Threads::gc_prologue();
179 BiasedLocking::preserve_marks();
180
181 // Capture heap size before collection for printing.
182 size_t prev_used = heap->used();
183
184 // Capture perm gen size before collection for sizing.
185 size_t perm_gen_prev_used = perm_gen->used_in_bytes();
186
187 // For PrintGCDetails
188 size_t old_gen_prev_used = old_gen->used_in_bytes();
189 size_t young_gen_prev_used = young_gen->used_in_bytes();
190
191 allocate_stacks();
192
193 COMPILER2_PRESENT(DerivedPointerTable::clear());
194
195 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
196 ref_processor()->setup_policy(clear_all_softrefs);
197
198 mark_sweep_phase1(clear_all_softrefs);
199
200 mark_sweep_phase2();
201
202 // Don't add any more derived pointers during phase3
203 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
204 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
205
206 mark_sweep_phase3();
207
208 mark_sweep_phase4();
209
210 restore_marks();
211
212 deallocate_stacks();
213
214 if (ZapUnusedHeapArea) {
215 // Do a complete mangle (top to end) because the usage for
216 // scratch does not maintain a top pointer.
217 young_gen->to_space()->mangle_unused_area_complete();
218 }
219
220 eden_empty = young_gen->eden_space()->is_empty();
221 if (!eden_empty) {
222 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
223 }
224
225 // Update heap occupancy information which is used as
226 // input to soft ref clearing policy at the next gc.
227 Universe::update_heap_info_at_gc();
228
229 survivors_empty = young_gen->from_space()->is_empty() &&
230 young_gen->to_space()->is_empty();
231 young_gen_empty = eden_empty && survivors_empty;
232
233 BarrierSet* bs = heap->barrier_set();
234 if (bs->is_a(BarrierSet::ModRef)) {
235 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
236 MemRegion old_mr = heap->old_gen()->reserved();
237 MemRegion perm_mr = heap->perm_gen()->reserved();
238 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
239
240 if (young_gen_empty) {
241 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
242 } else {
243 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
244 }
245 }
246
247 BiasedLocking::restore_marks();
248 Threads::gc_epilogue();
249 CodeCache::gc_epilogue();
250 JvmtiExport::gc_epilogue();
251
252 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
253
254 ref_processor()->enqueue_discovered_references(NULL);
255
256 // Update time of last GC
257 reset_millis_since_last_gc();
258
259 // Let the size policy know we're done
260 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
261
262 if (UseAdaptiveSizePolicy) {
263
264 if (PrintAdaptiveSizePolicy) {
265 gclog_or_tty->print("AdaptiveSizeStart: ");
266 gclog_or_tty->stamp();
267 gclog_or_tty->print_cr(" collection: %d ",
268 heap->total_collections());
269 if (Verbose) {
270 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
271 " perm_gen_capacity: %d ",
272 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
273 perm_gen->capacity_in_bytes());
274 }
275 }
276
277 // Don't check if the size_policy is ready here. Let
278 // the size_policy check that internally.
279 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
280 ((gc_cause != GCCause::_java_lang_system_gc) ||
281 UseAdaptiveSizePolicyWithSystemGC)) {
282 // Calculate optimal free space amounts
283 assert(young_gen->max_size() >
284 young_gen->from_space()->capacity_in_bytes() +
285 young_gen->to_space()->capacity_in_bytes(),
286 "Sizes of space in young gen are out-of-bounds");
287 size_t max_eden_size = young_gen->max_size() -
288 young_gen->from_space()->capacity_in_bytes() -
289 young_gen->to_space()->capacity_in_bytes();
290 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
291 young_gen->eden_space()->used_in_bytes(),
292 old_gen->used_in_bytes(),
293 perm_gen->used_in_bytes(),
294 young_gen->eden_space()->capacity_in_bytes(),
295 old_gen->max_gen_size(),
296 max_eden_size,
297 true /* full gc*/,
298 gc_cause,
299 heap->collector_policy());
300
301 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
302
303 // Don't resize the young generation at an major collection. A
304 // desired young generation size may have been calculated but
305 // resizing the young generation complicates the code because the
306 // resizing of the old generation may have moved the boundary
307 // between the young generation and the old generation. Let the
308 // young generation resizing happen at the minor collections.
309 }
310 if (PrintAdaptiveSizePolicy) {
311 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
312 heap->total_collections());
313 }
314 }
315
316 if (UsePerfData) {
317 heap->gc_policy_counters()->update_counters();
318 heap->gc_policy_counters()->update_old_capacity(
319 old_gen->capacity_in_bytes());
320 heap->gc_policy_counters()->update_young_capacity(
321 young_gen->capacity_in_bytes());
322 }
323
324 heap->resize_all_tlabs();
325
326 // We collected the perm gen, so we'll resize it here.
327 perm_gen->compute_new_size(perm_gen_prev_used);
328
329 if (TraceGen1Time) accumulated_time()->stop();
330
331 if (PrintGC) {
332 if (PrintGCDetails) {
333 // Don't print a GC timestamp here. This is after the GC so
334 // would be confusing.
335 young_gen->print_used_change(young_gen_prev_used);
336 old_gen->print_used_change(old_gen_prev_used);
337 }
338 heap->print_heap_change(prev_used);
339 // Do perm gen after heap becase prev_used does
340 // not include the perm gen (done this way in the other
341 // collectors).
342 if (PrintGCDetails) {
343 perm_gen->print_used_change(perm_gen_prev_used);
344 }
345 }
346
347 // Track memory usage and detect low memory
348 MemoryService::track_memory_usage();
349 heap->update_counters();
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 heap->print_heap_after_gc();
373
374 heap->post_full_gc_dump();
375
376 #ifdef TRACESPINNING
377 ParallelTaskTerminator::print_termination_counts();
378 #endif
379
380 return true;
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
487
488 void PSMarkSweep::deallocate_stacks() {
489 _preserved_mark_stack.clear(true);
490 _preserved_oop_stack.clear(true);
491 _marking_stack.clear();
492 _objarray_stack.clear(true);
493 _revisit_klass_stack.clear(true);
494 _revisit_mdo_stack.clear(true);
495 }
496
497 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
498 // Recursively traverse all live objects and mark them
499 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty);
500 trace(" 1");
501
502 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
503 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
504
505 // General strong roots.
506 {
507 ParallelScavengeHeap::ParStrongRootsScope psrs;
508 Universe::oops_do(mark_and_push_closure());
509 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
510 CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
511 Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
512 ObjectSynchronizer::oops_do(mark_and_push_closure());
513 FlatProfiler::oops_do(mark_and_push_closure());
514 Management::oops_do(mark_and_push_closure());
515 JvmtiExport::oops_do(mark_and_push_closure());
516 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
517 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
518 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
519 }
520
521 // Flush marking stack.
522 follow_stack();
523
524 // Process reference objects found during marking
525 {
526 ref_processor()->setup_policy(clear_all_softrefs);
527 ref_processor()->process_discovered_references(
528 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL);
529 }
530
531 // Follow system dictionary roots and unload classes
532 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
533
534 // Follow code cache roots
535 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(),
536 purged_class);
537 follow_stack(); // Flush marking stack
538
539 // Update subklass/sibling/implementor links of live klasses
540 follow_weak_klass_links();
541 assert(_marking_stack.is_empty(), "just drained");
542
543 // Visit memoized mdo's and clear unmarked weak refs
544 follow_mdo_weak_refs();
545 assert(_marking_stack.is_empty(), "just drained");
546
547 // Visit interned string tables and delete unmarked oops
548 StringTable::unlink(is_alive_closure());
549 // Clean up unreferenced symbols in symbol table.
550 SymbolTable::unlink();
551
552 assert(_marking_stack.is_empty(), "stack should be empty by now");
553 }
554
555
556 void PSMarkSweep::mark_sweep_phase2() {
557 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty);
558 trace("2");
559
560 // Now all live objects are marked, compute the new object addresses.
561
562 // It is imperative that we traverse perm_gen LAST. If dead space is
563 // allowed a range of dead object may get overwritten by a dead int
564 // array. If perm_gen is not traversed last a klassOop may get
565 // overwritten. This is fine since it is dead, but if the class has dead
566 // instances we have to skip them, and in order to find their size we
567 // need the klassOop!
568 //
569 // It is not required that we traverse spaces in the same order in
570 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
571 // tracking expects us to do so. See comment under phase4.
572
573 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
574 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
575
576 PSOldGen* old_gen = heap->old_gen();
577 PSPermGen* perm_gen = heap->perm_gen();
578
579 // Begin compacting into the old gen
580 PSMarkSweepDecorator::set_destination_decorator_tenured();
581
582 // This will also compact the young gen spaces.
583 old_gen->precompact();
584
585 // Compact the perm gen into the perm gen
586 PSMarkSweepDecorator::set_destination_decorator_perm_gen();
587
588 perm_gen->precompact();
589 }
590
591 // This should be moved to the shared markSweep code!
592 class PSAlwaysTrueClosure: public BoolObjectClosure {
593 public:
594 void do_object(oop p) { ShouldNotReachHere(); }
595 bool do_object_b(oop p) { return true; }
596 };
597 static PSAlwaysTrueClosure always_true;
598
599 void PSMarkSweep::mark_sweep_phase3() {
600 // Adjust the pointers to reflect the new locations
601 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty);
602 trace("3");
603
604 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
605 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
606
607 PSYoungGen* young_gen = heap->young_gen();
608 PSOldGen* old_gen = heap->old_gen();
609 PSPermGen* perm_gen = heap->perm_gen();
610
611 // General strong roots.
612 Universe::oops_do(adjust_root_pointer_closure());
613 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
614 Threads::oops_do(adjust_root_pointer_closure(), NULL);
615 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
616 FlatProfiler::oops_do(adjust_root_pointer_closure());
617 Management::oops_do(adjust_root_pointer_closure());
618 JvmtiExport::oops_do(adjust_root_pointer_closure());
619 // SO_AllClasses
620 SystemDictionary::oops_do(adjust_root_pointer_closure());
621 //CodeCache::scavenge_root_nmethods_oops_do(adjust_root_pointer_closure());
622
623 // Now adjust pointers in remaining weak roots. (All of which should
624 // have been cleared if they pointed to non-surviving objects.)
625 // Global (weak) JNI handles
626 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
627
628 CodeCache::oops_do(adjust_pointer_closure());
629 StringTable::oops_do(adjust_root_pointer_closure());
630 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
631 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure());
632
633 adjust_marks();
634
635 young_gen->adjust_pointers();
636 old_gen->adjust_pointers();
637 perm_gen->adjust_pointers();
638 }
639
640 void PSMarkSweep::mark_sweep_phase4() {
641 EventMark m("4 compact heap");
642 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty);
643 trace("4");
644
645 // All pointers are now adjusted, move objects accordingly
646
647 // It is imperative that we traverse perm_gen first in phase4. All
648 // classes must be allocated earlier than their instances, and traversing
649 // perm_gen first makes sure that all klassOops have moved to their new
650 // location before any instance does a dispatch through it's klass!
651 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
652 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
653
654 PSYoungGen* young_gen = heap->young_gen();
655 PSOldGen* old_gen = heap->old_gen();
656 PSPermGen* perm_gen = heap->perm_gen();
657
658 perm_gen->compact();
659 old_gen->compact();
660 young_gen->compact();
661 }
662
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 }
675
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 }