1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)psMarkSweep.cpp 1.92 07/06/08 23:11:01 JVM"
3 #endif
4 /*
5 * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 #include "incls/_precompiled.incl"
29 #include "incls/_psMarkSweep.cpp.incl"
30
31 elapsedTimer PSMarkSweep::_accumulated_time;
32 unsigned int PSMarkSweep::_total_invocations = 0;
33 jlong PSMarkSweep::_time_of_last_gc = 0;
34 CollectorCounters* PSMarkSweep::_counters = NULL;
35
36 void PSMarkSweep::initialize() {
37 MemRegion mr = Universe::heap()->reserved_region();
38 _ref_processor = new ReferenceProcessor(mr,
39 true, // atomic_discovery
40 false); // mt_discovery
41 _counters = new CollectorCounters("PSMarkSweep", 1);
42 }
43
44 // This method contains all heap specific policy for invoking mark sweep.
45 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
46 // the heap. It will do nothing further. If we need to bail out for policy
47 // reasons, scavenge before full gc, or any other specialized behavior, it
48 // needs to be added here.
49 //
50 // Note that this method should only be called from the vm_thread while
51 // at a safepoint!
52 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
53 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
54 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
55 assert(!Universe::heap()->is_gc_active(), "not reentrant");
56
57 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
58 GCCause::Cause gc_cause = heap->gc_cause();
59 PSAdaptiveSizePolicy* policy = heap->size_policy();
60
61 // Before each allocation/collection attempt, find out from the
62 // policy object if GCs are, on the whole, taking too long. If so,
63 // bail out without attempting a collection. The exceptions are
64 // for explicitly requested GC's.
65 if (!policy->gc_time_limit_exceeded() ||
66 GCCause::is_user_requested_gc(gc_cause) ||
67 GCCause::is_serviceability_requested_gc(gc_cause)) {
68 IsGCActiveMark mark;
69
70 if (ScavengeBeforeFullGC) {
71 PSScavenge::invoke_no_policy();
72 }
73
74 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount;
75 IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
76 PSMarkSweep::invoke_no_policy(maximum_heap_compaction);
77 }
78 }
79
80 // This method contains no policy. You should probably
81 // be calling invoke() instead.
82 void PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
83 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
84 assert(ref_processor() != NULL, "Sanity");
85
86 if (GC_locker::check_active_before_gc()) {
87 return;
88 }
89
90 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
91 GCCause::Cause gc_cause = heap->gc_cause();
92 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
93 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
94
95 PSYoungGen* young_gen = heap->young_gen();
96 PSOldGen* old_gen = heap->old_gen();
97 PSPermGen* perm_gen = heap->perm_gen();
98
99 // Increment the invocation count
100 heap->increment_total_collections(true /* full */);
101
102 // Save information needed to minimize mangling
103 heap->record_gen_tops_before_GC();
104
105 // We need to track unique mark sweep invocations as well.
106 _total_invocations++;
107
108 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
109
110 if (PrintHeapAtGC) {
111 Universe::print_heap_before_gc();
112 }
113
114 // Fill in TLABs
115 heap->accumulate_statistics_all_tlabs();
116 heap->ensure_parsability(true); // retire TLABs
117
118 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
119 HandleMark hm; // Discard invalid handles created during verification
120 gclog_or_tty->print(" VerifyBeforeGC:");
121 Universe::verify(true);
122 }
123
124 // Verify object start arrays
125 if (VerifyObjectStartArray &&
126 VerifyBeforeGC) {
127 old_gen->verify_object_start_array();
128 perm_gen->verify_object_start_array();
129 }
130
131 // Filled in below to track the state of the young gen after the collection.
132 bool eden_empty;
133 bool survivors_empty;
134 bool young_gen_empty;
135
136 {
137 HandleMark hm;
138 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
139 // This is useful for debugging but don't change the output the
140 // the customer sees.
141 const char* gc_cause_str = "Full GC";
142 if (is_system_gc && PrintGCDetails) {
143 gc_cause_str = "Full GC (System)";
144 }
145 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
146 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
147 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
148 TraceCollectorStats tcs(counters());
149 TraceMemoryManagerStats tms(true /* Full GC */);
150
151 if (TraceGen1Time) accumulated_time()->start();
152
153 // Let the size policy know we're starting
154 size_policy->major_collection_begin();
155
156 // When collecting the permanent generation methodOops may be moving,
157 // so we either have to flush all bcp data or convert it into bci.
158 CodeCache::gc_prologue();
159 Threads::gc_prologue();
160 BiasedLocking::preserve_marks();
161
162 // Capture heap size before collection for printing.
163 size_t prev_used = heap->used();
164
165 // Capture perm gen size before collection for sizing.
166 size_t perm_gen_prev_used = perm_gen->used_in_bytes();
167
168 // For PrintGCDetails
169 size_t old_gen_prev_used = old_gen->used_in_bytes();
170 size_t young_gen_prev_used = young_gen->used_in_bytes();
171
172 allocate_stacks();
173
174 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
175 COMPILER2_PRESENT(DerivedPointerTable::clear());
176
177 ref_processor()->enable_discovery();
178 ref_processor()->setup_policy(clear_all_softrefs);
179
180 mark_sweep_phase1(clear_all_softrefs);
181
182 mark_sweep_phase2();
183
184 // Don't add any more derived pointers during phase3
185 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
186 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
187
188 mark_sweep_phase3();
189
190 mark_sweep_phase4();
191
192 restore_marks();
193
194 deallocate_stacks();
195
196 if (ZapUnusedHeapArea) {
197 // Do a complete mangle (top to end) because the usage for
198 // scratch does not maintain a top pointer.
199 young_gen->to_space()->mangle_unused_area_complete();
200 }
201
202 eden_empty = young_gen->eden_space()->is_empty();
203 if (!eden_empty) {
204 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
205 }
206
207 // Update heap occupancy information which is used as
208 // input to soft ref clearing policy at the next gc.
209 Universe::update_heap_info_at_gc();
210
211 survivors_empty = young_gen->from_space()->is_empty() &&
212 young_gen->to_space()->is_empty();
213 young_gen_empty = eden_empty && survivors_empty;
214
215 BarrierSet* bs = heap->barrier_set();
216 if (bs->is_a(BarrierSet::ModRef)) {
217 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
218 MemRegion old_mr = heap->old_gen()->reserved();
219 MemRegion perm_mr = heap->perm_gen()->reserved();
220 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
221
222 if (young_gen_empty) {
223 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
224 } else {
225 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
226 }
227 }
228
229 BiasedLocking::restore_marks();
230 Threads::gc_epilogue();
231 CodeCache::gc_epilogue();
232
233 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
234
235 ref_processor()->enqueue_discovered_references(NULL);
236
237 // Update time of last GC
238 reset_millis_since_last_gc();
239
240 // Let the size policy know we're done
241 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
242
243 if (UseAdaptiveSizePolicy) {
244
245 if (PrintAdaptiveSizePolicy) {
246 gclog_or_tty->print("AdaptiveSizeStart: ");
247 gclog_or_tty->stamp();
248 gclog_or_tty->print_cr(" collection: %d ",
249 heap->total_collections());
250 if (Verbose) {
251 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
252 " perm_gen_capacity: %d ",
253 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
254 perm_gen->capacity_in_bytes());
255 }
256 }
257
258 // Don't check if the size_policy is ready here. Let
259 // the size_policy check that internally.
260 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
261 ((gc_cause != GCCause::_java_lang_system_gc) ||
262 UseAdaptiveSizePolicyWithSystemGC)) {
263 // Calculate optimal free space amounts
264 assert(young_gen->max_size() >
265 young_gen->from_space()->capacity_in_bytes() +
266 young_gen->to_space()->capacity_in_bytes(),
267 "Sizes of space in young gen are out-of-bounds");
268 size_t max_eden_size = young_gen->max_size() -
269 young_gen->from_space()->capacity_in_bytes() -
270 young_gen->to_space()->capacity_in_bytes();
271 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
272 young_gen->eden_space()->used_in_bytes(),
273 old_gen->used_in_bytes(),
274 perm_gen->used_in_bytes(),
275 young_gen->eden_space()->capacity_in_bytes(),
276 old_gen->max_gen_size(),
277 max_eden_size,
278 true /* full gc*/,
279 gc_cause);
280
281 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
282
283 // Don't resize the young generation at an major collection. A
284 // desired young generation size may have been calculated but
285 // resizing the young generation complicates the code because the
286 // resizing of the old generation may have moved the boundary
287 // between the young generation and the old generation. Let the
288 // young generation resizing happen at the minor collections.
289 }
290 if (PrintAdaptiveSizePolicy) {
291 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
292 heap->total_collections());
293 }
294 }
295
296 if (UsePerfData) {
297 heap->gc_policy_counters()->update_counters();
298 heap->gc_policy_counters()->update_old_capacity(
299 old_gen->capacity_in_bytes());
300 heap->gc_policy_counters()->update_young_capacity(
301 young_gen->capacity_in_bytes());
302 }
303
304 heap->resize_all_tlabs();
305
306 // We collected the perm gen, so we'll resize it here.
307 perm_gen->compute_new_size(perm_gen_prev_used);
308
309 if (TraceGen1Time) accumulated_time()->stop();
310
311 if (PrintGC) {
312 if (PrintGCDetails) {
313 // Don't print a GC timestamp here. This is after the GC so
314 // would be confusing.
315 young_gen->print_used_change(young_gen_prev_used);
316 old_gen->print_used_change(old_gen_prev_used);
317 }
318 heap->print_heap_change(prev_used);
319 // Do perm gen after heap becase prev_used does
320 // not include the perm gen (done this way in the other
321 // collectors).
322 if (PrintGCDetails) {
323 perm_gen->print_used_change(perm_gen_prev_used);
324 }
325 }
326
327 // Track memory usage and detect low memory
328 MemoryService::track_memory_usage();
329 heap->update_counters();
330
331 if (PrintGCDetails) {
332 if (size_policy->print_gc_time_limit_would_be_exceeded()) {
333 if (size_policy->gc_time_limit_exceeded()) {
334 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit "
335 "of %d%%", GCTimeLimit);
336 } else {
337 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit "
338 "of %d%%", GCTimeLimit);
339 }
340 }
341 size_policy->set_print_gc_time_limit_would_be_exceeded(false);
342 }
343 }
344
345 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
346 HandleMark hm; // Discard invalid handles created during verification
347 gclog_or_tty->print(" VerifyAfterGC:");
348 Universe::verify(false);
349 }
350
351 // Re-verify object start arrays
352 if (VerifyObjectStartArray &&
353 VerifyAfterGC) {
354 old_gen->verify_object_start_array();
355 perm_gen->verify_object_start_array();
356 }
357
358 if (ZapUnusedHeapArea) {
359 old_gen->object_space()->check_mangled_unused_area_complete();
360 perm_gen->object_space()->check_mangled_unused_area_complete();
361 }
362
363 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
364
365 if (PrintHeapAtGC) {
366 Universe::print_heap_after_gc();
367 }
368 }
369
370 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
371 PSYoungGen* young_gen,
372 PSOldGen* old_gen) {
373 MutableSpace* const eden_space = young_gen->eden_space();
374 assert(!eden_space->is_empty(), "eden must be non-empty");
375 assert(young_gen->virtual_space()->alignment() ==
376 old_gen->virtual_space()->alignment(), "alignments do not match");
377
378 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
379 return false;
380 }
381
382 // Both generations must be completely committed.
383 if (young_gen->virtual_space()->uncommitted_size() != 0) {
384 return false;
385 }
386 if (old_gen->virtual_space()->uncommitted_size() != 0) {
387 return false;
388 }
389
390 // Figure out how much to take from eden. Include the average amount promoted
391 // in the total; otherwise the next young gen GC will simply bail out to a
392 // full GC.
393 const size_t alignment = old_gen->virtual_space()->alignment();
394 const size_t eden_used = eden_space->used_in_bytes();
395 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
396 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
397 const size_t eden_capacity = eden_space->capacity_in_bytes();
398
399 if (absorb_size >= eden_capacity) {
400 return false; // Must leave some space in eden.
401 }
402
403 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
404 if (new_young_size < young_gen->min_gen_size()) {
405 return false; // Respect young gen minimum size.
406 }
407
408 if (TraceAdaptiveGCBoundary && Verbose) {
409 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
410 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
411 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
412 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
413 absorb_size / K,
414 eden_capacity / K, (eden_capacity - absorb_size) / K,
415 young_gen->from_space()->used_in_bytes() / K,
416 young_gen->to_space()->used_in_bytes() / K,
417 young_gen->capacity_in_bytes() / K, new_young_size / K);
418 }
419
420 // Fill the unused part of the old gen.
421 MutableSpace* const old_space = old_gen->object_space();
422 HeapWord* const unused_start = old_space->top();
423 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
424
425 if (unused_words > 0) {
426 if (unused_words < CollectedHeap::min_fill_size()) {
427 return false; // If the old gen cannot be filled, must give up.
428 }
429 CollectedHeap::fill_with_objects(unused_start, unused_words);
430 }
431
432 // Take the live data from eden and set both top and end in the old gen to
433 // eden top. (Need to set end because reset_after_change() mangles the region
434 // from end to virtual_space->high() in debug builds).
435 HeapWord* const new_top = eden_space->top();
436 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
437 absorb_size);
438 young_gen->reset_after_change();
439 old_space->set_top(new_top);
440 old_space->set_end(new_top);
441 old_gen->reset_after_change();
442
443 // Update the object start array for the filler object and the data from eden.
444 ObjectStartArray* const start_array = old_gen->start_array();
445 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
446 start_array->allocate_block(p);
447 }
448
449 // Could update the promoted average here, but it is not typically updated at
450 // full GCs and the value to use is unclear. Something like
451 //
452 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
453
454 size_policy->set_bytes_absorbed_from_eden(absorb_size);
455 return true;
456 }
457
458 void PSMarkSweep::allocate_stacks() {
459 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
460 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
461
462 PSYoungGen* young_gen = heap->young_gen();
463
464 MutableSpace* to_space = young_gen->to_space();
465 _preserved_marks = (PreservedMark*)to_space->top();
466 _preserved_count = 0;
467
468 // We want to calculate the size in bytes first.
469 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
470 // Now divide by the size of a PreservedMark
471 _preserved_count_max /= sizeof(PreservedMark);
472
473 _preserved_mark_stack = NULL;
474 _preserved_oop_stack = NULL;
475
476 _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
477
478 int size = SystemDictionary::number_of_classes() * 2;
479 _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
480 }
481
482
483 void PSMarkSweep::deallocate_stacks() {
484 if (_preserved_oop_stack) {
485 delete _preserved_mark_stack;
486 _preserved_mark_stack = NULL;
487 delete _preserved_oop_stack;
488 _preserved_oop_stack = NULL;
489 }
490
491 delete _marking_stack;
492 delete _revisit_klass_stack;
493 }
494
495 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
496 // Recursively traverse all live objects and mark them
497 EventMark m("1 mark object");
498 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty);
499 trace(" 1");
500
501 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
502 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
503
504 // General strong roots.
505 Universe::oops_do(mark_and_push_closure());
506 ReferenceProcessor::oops_do(mark_and_push_closure());
507 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
508 Threads::oops_do(mark_and_push_closure());
509 ObjectSynchronizer::oops_do(mark_and_push_closure());
510 FlatProfiler::oops_do(mark_and_push_closure());
511 Management::oops_do(mark_and_push_closure());
512 JvmtiExport::oops_do(mark_and_push_closure());
513 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
514 vmSymbols::oops_do(mark_and_push_closure());
515
516 // Flush marking stack.
517 follow_stack();
518
519 // Process reference objects found during marking
520 {
521 ref_processor()->setup_policy(clear_all_softrefs);
522 ref_processor()->process_discovered_references(
523 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL);
524 }
525
526 // Follow system dictionary roots and unload classes
527 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
528
529 // Follow code cache roots
530 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(),
531 purged_class);
532 follow_stack(); // Flush marking stack
533
534 // Update subklass/sibling/implementor links of live klasses
535 follow_weak_klass_links();
536 assert(_marking_stack->is_empty(), "just drained");
537
538 // Visit symbol and interned string tables and delete unmarked oops
539 SymbolTable::unlink(is_alive_closure());
540 StringTable::unlink(is_alive_closure());
541
542 assert(_marking_stack->is_empty(), "stack should be empty by now");
543 }
544
545
546 void PSMarkSweep::mark_sweep_phase2() {
547 EventMark m("2 compute new addresses");
548 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty);
549 trace("2");
550
551 // Now all live objects are marked, compute the new object addresses.
552
553 // It is imperative that we traverse perm_gen LAST. If dead space is
554 // allowed a range of dead object may get overwritten by a dead int
555 // array. If perm_gen is not traversed last a klassOop may get
556 // overwritten. This is fine since it is dead, but if the class has dead
557 // instances we have to skip them, and in order to find their size we
558 // need the klassOop!
559 //
560 // It is not required that we traverse spaces in the same order in
561 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
562 // tracking expects us to do so. See comment under phase4.
563
564 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
565 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
566
567 PSOldGen* old_gen = heap->old_gen();
568 PSPermGen* perm_gen = heap->perm_gen();
569
570 // Begin compacting into the old gen
571 PSMarkSweepDecorator::set_destination_decorator_tenured();
572
573 // This will also compact the young gen spaces.
574 old_gen->precompact();
575
576 // Compact the perm gen into the perm gen
577 PSMarkSweepDecorator::set_destination_decorator_perm_gen();
578
579 perm_gen->precompact();
580 }
581
582 // This should be moved to the shared markSweep code!
583 class PSAlwaysTrueClosure: public BoolObjectClosure {
584 public:
585 void do_object(oop p) { ShouldNotReachHere(); }
586 bool do_object_b(oop p) { return true; }
587 };
588 static PSAlwaysTrueClosure always_true;
589
590 void PSMarkSweep::mark_sweep_phase3() {
591 // Adjust the pointers to reflect the new locations
592 EventMark m("3 adjust pointers");
593 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty);
594 trace("3");
595
596 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
597 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
598
599 PSYoungGen* young_gen = heap->young_gen();
600 PSOldGen* old_gen = heap->old_gen();
601 PSPermGen* perm_gen = heap->perm_gen();
602
603 // General strong roots.
604 Universe::oops_do(adjust_root_pointer_closure());
605 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
606 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
607 Threads::oops_do(adjust_root_pointer_closure());
608 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
609 FlatProfiler::oops_do(adjust_root_pointer_closure());
610 Management::oops_do(adjust_root_pointer_closure());
611 JvmtiExport::oops_do(adjust_root_pointer_closure());
612 // SO_AllClasses
613 SystemDictionary::oops_do(adjust_root_pointer_closure());
614 vmSymbols::oops_do(adjust_root_pointer_closure());
615
616 // Now adjust pointers in remaining weak roots. (All of which should
617 // have been cleared if they pointed to non-surviving objects.)
618 // Global (weak) JNI handles
619 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
620
621 CodeCache::oops_do(adjust_pointer_closure());
622 SymbolTable::oops_do(adjust_root_pointer_closure());
623 StringTable::oops_do(adjust_root_pointer_closure());
624 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
625 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure());
626
627 adjust_marks();
628
629 young_gen->adjust_pointers();
630 old_gen->adjust_pointers();
631 perm_gen->adjust_pointers();
632 }
633
634 void PSMarkSweep::mark_sweep_phase4() {
635 EventMark m("4 compact heap");
636 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty);
637 trace("4");
638
639 // All pointers are now adjusted, move objects accordingly
640
641 // It is imperative that we traverse perm_gen first in phase4. All
642 // classes must be allocated earlier than their instances, and traversing
643 // perm_gen first makes sure that all klassOops have moved to their new
644 // location before any instance does a dispatch through it's klass!
645 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
646 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
647
648 PSYoungGen* young_gen = heap->young_gen();
649 PSOldGen* old_gen = heap->old_gen();
650 PSPermGen* perm_gen = heap->perm_gen();
651
652 perm_gen->compact();
653 old_gen->compact();
654 young_gen->compact();
655 }
656
657 jlong PSMarkSweep::millis_since_last_gc() {
658 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
659 // XXX See note in genCollectedHeap::millis_since_last_gc().
660 if (ret_val < 0) {
661 NOT_PRODUCT(warning("time warp: %d", ret_val);)
662 return 0;
663 }
664 return ret_val;
665 }
666
667 void PSMarkSweep::reset_millis_since_last_gc() {
668 _time_of_last_gc = os::javaTimeMillis();
669 }