1 /*
2 * Copyright 2001-2008 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 // Filled in below to track the state of the young gen after the collection.
129 bool eden_empty;
130 bool survivors_empty;
131 bool young_gen_empty;
132
133 {
134 HandleMark hm;
135 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
136 // This is useful for debugging but don't change the output the
137 // the customer sees.
138 const char* gc_cause_str = "Full GC";
139 if (is_system_gc && PrintGCDetails) {
140 gc_cause_str = "Full GC (System)";
141 }
142 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
143 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
144 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
145 TraceCollectorStats tcs(counters());
146 TraceMemoryManagerStats tms(true /* Full GC */);
147
148 if (TraceGen1Time) accumulated_time()->start();
149
150 // Let the size policy know we're starting
151 size_policy->major_collection_begin();
152
153 // When collecting the permanent generation methodOops may be moving,
154 // so we either have to flush all bcp data or convert it into bci.
155 CodeCache::gc_prologue();
156 Threads::gc_prologue();
157 BiasedLocking::preserve_marks();
158
159 // Capture heap size before collection for printing.
160 size_t prev_used = heap->used();
161
162 // Capture perm gen size before collection for sizing.
163 size_t perm_gen_prev_used = perm_gen->used_in_bytes();
164
165 // For PrintGCDetails
166 size_t old_gen_prev_used = old_gen->used_in_bytes();
167 size_t young_gen_prev_used = young_gen->used_in_bytes();
168
169 allocate_stacks();
170
171 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
172 COMPILER2_PRESENT(DerivedPointerTable::clear());
173
174 ref_processor()->enable_discovery();
175
176 mark_sweep_phase1(clear_all_softrefs);
177
178 mark_sweep_phase2();
179
180 // Don't add any more derived pointers during phase3
181 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
182 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
183
184 mark_sweep_phase3();
185
186 mark_sweep_phase4();
187
188 restore_marks();
189
190 deallocate_stacks();
191
192 if (ZapUnusedHeapArea) {
193 // Do a complete mangle (top to end) because the usage for
194 // scratch does not maintain a top pointer.
195 young_gen->to_space()->mangle_unused_area_complete();
196 }
197
198 eden_empty = young_gen->eden_space()->is_empty();
199 if (!eden_empty) {
200 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
201 }
202
203 // Update heap occupancy information which is used as
204 // input to soft ref clearing policy at the next gc.
205 Universe::update_heap_info_at_gc();
206
207 survivors_empty = young_gen->from_space()->is_empty() &&
208 young_gen->to_space()->is_empty();
209 young_gen_empty = eden_empty && survivors_empty;
210
211 BarrierSet* bs = heap->barrier_set();
212 if (bs->is_a(BarrierSet::ModRef)) {
213 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
214 MemRegion old_mr = heap->old_gen()->reserved();
215 MemRegion perm_mr = heap->perm_gen()->reserved();
216 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
217
218 if (young_gen_empty) {
219 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
220 } else {
221 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
222 }
223 }
224
225 BiasedLocking::restore_marks();
226 Threads::gc_epilogue();
227 CodeCache::gc_epilogue();
228
229 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
230
231 ref_processor()->enqueue_discovered_references(NULL);
232
233 // Update time of last GC
234 reset_millis_since_last_gc();
235
236 // Let the size policy know we're done
237 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
238
239 if (UseAdaptiveSizePolicy) {
240
241 if (PrintAdaptiveSizePolicy) {
242 gclog_or_tty->print("AdaptiveSizeStart: ");
243 gclog_or_tty->stamp();
244 gclog_or_tty->print_cr(" collection: %d ",
245 heap->total_collections());
246 if (Verbose) {
247 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
248 " perm_gen_capacity: %d ",
249 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
250 perm_gen->capacity_in_bytes());
251 }
252 }
253
254 // Don't check if the size_policy is ready here. Let
255 // the size_policy check that internally.
256 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
257 ((gc_cause != GCCause::_java_lang_system_gc) ||
258 UseAdaptiveSizePolicyWithSystemGC)) {
259 // Calculate optimal free space amounts
260 assert(young_gen->max_size() >
261 young_gen->from_space()->capacity_in_bytes() +
262 young_gen->to_space()->capacity_in_bytes(),
263 "Sizes of space in young gen are out-of-bounds");
264 size_t max_eden_size = young_gen->max_size() -
265 young_gen->from_space()->capacity_in_bytes() -
266 young_gen->to_space()->capacity_in_bytes();
267 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
268 young_gen->eden_space()->used_in_bytes(),
269 old_gen->used_in_bytes(),
270 perm_gen->used_in_bytes(),
271 young_gen->eden_space()->capacity_in_bytes(),
272 old_gen->max_gen_size(),
273 max_eden_size,
274 true /* full gc*/,
275 gc_cause);
276
277 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
278
279 // Don't resize the young generation at an major collection. A
280 // desired young generation size may have been calculated but
281 // resizing the young generation complicates the code because the
282 // resizing of the old generation may have moved the boundary
283 // between the young generation and the old generation. Let the
284 // young generation resizing happen at the minor collections.
285 }
286 if (PrintAdaptiveSizePolicy) {
287 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
288 heap->total_collections());
289 }
290 }
291
292 if (UsePerfData) {
293 heap->gc_policy_counters()->update_counters();
294 heap->gc_policy_counters()->update_old_capacity(
295 old_gen->capacity_in_bytes());
296 heap->gc_policy_counters()->update_young_capacity(
297 young_gen->capacity_in_bytes());
298 }
299
300 heap->resize_all_tlabs();
301
302 // We collected the perm gen, so we'll resize it here.
303 perm_gen->compute_new_size(perm_gen_prev_used);
304
305 if (TraceGen1Time) accumulated_time()->stop();
306
307 if (PrintGC) {
308 if (PrintGCDetails) {
309 // Don't print a GC timestamp here. This is after the GC so
310 // would be confusing.
311 young_gen->print_used_change(young_gen_prev_used);
312 old_gen->print_used_change(old_gen_prev_used);
313 }
314 heap->print_heap_change(prev_used);
315 // Do perm gen after heap becase prev_used does
316 // not include the perm gen (done this way in the other
317 // collectors).
318 if (PrintGCDetails) {
319 perm_gen->print_used_change(perm_gen_prev_used);
320 }
321 }
322
323 // Track memory usage and detect low memory
324 MemoryService::track_memory_usage();
325 heap->update_counters();
326
327 if (PrintGCDetails) {
328 if (size_policy->print_gc_time_limit_would_be_exceeded()) {
329 if (size_policy->gc_time_limit_exceeded()) {
330 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit "
331 "of %d%%", GCTimeLimit);
332 } else {
333 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit "
334 "of %d%%", GCTimeLimit);
335 }
336 }
337 size_policy->set_print_gc_time_limit_would_be_exceeded(false);
338 }
339 }
340
341 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
342 HandleMark hm; // Discard invalid handles created during verification
343 gclog_or_tty->print(" VerifyAfterGC:");
344 Universe::verify(false);
345 }
346
347 // Re-verify object start arrays
348 if (VerifyObjectStartArray &&
349 VerifyAfterGC) {
350 old_gen->verify_object_start_array();
351 perm_gen->verify_object_start_array();
352 }
353
354 if (ZapUnusedHeapArea) {
355 old_gen->object_space()->check_mangled_unused_area_complete();
356 perm_gen->object_space()->check_mangled_unused_area_complete();
357 }
358
359 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
360
361 if (PrintHeapAtGC) {
362 Universe::print_heap_after_gc();
363 }
364 }
365
366 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
367 PSYoungGen* young_gen,
368 PSOldGen* old_gen) {
369 MutableSpace* const eden_space = young_gen->eden_space();
370 assert(!eden_space->is_empty(), "eden must be non-empty");
371 assert(young_gen->virtual_space()->alignment() ==
372 old_gen->virtual_space()->alignment(), "alignments do not match");
373
374 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
375 return false;
376 }
377
378 // Both generations must be completely committed.
379 if (young_gen->virtual_space()->uncommitted_size() != 0) {
380 return false;
381 }
382 if (old_gen->virtual_space()->uncommitted_size() != 0) {
383 return false;
384 }
385
386 // Figure out how much to take from eden. Include the average amount promoted
387 // in the total; otherwise the next young gen GC will simply bail out to a
388 // full GC.
389 const size_t alignment = old_gen->virtual_space()->alignment();
390 const size_t eden_used = eden_space->used_in_bytes();
391 const size_t promoted = (size_t)(size_policy->avg_promoted()->padded_average());
392 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
393 const size_t eden_capacity = eden_space->capacity_in_bytes();
394
395 if (absorb_size >= eden_capacity) {
396 return false; // Must leave some space in eden.
397 }
398
399 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
400 if (new_young_size < young_gen->min_gen_size()) {
401 return false; // Respect young gen minimum size.
402 }
403
404 if (TraceAdaptiveGCBoundary && Verbose) {
405 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
406 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
407 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
408 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
409 absorb_size / K,
410 eden_capacity / K, (eden_capacity - absorb_size) / K,
411 young_gen->from_space()->used_in_bytes() / K,
412 young_gen->to_space()->used_in_bytes() / K,
413 young_gen->capacity_in_bytes() / K, new_young_size / K);
414 }
415
416 // Fill the unused part of the old gen.
417 MutableSpace* const old_space = old_gen->object_space();
418 MemRegion old_gen_unused(old_space->top(), old_space->end());
419
420 // If the unused part of the old gen cannot be filled, skip
421 // absorbing eden.
422 if (old_gen_unused.word_size() < SharedHeap::min_fill_size()) {
423 return false;
424 }
425
426 if (!old_gen_unused.is_empty()) {
427 SharedHeap::fill_region_with_object(old_gen_unused);
428 }
429
430 // Take the live data from eden and set both top and end in the old gen to
431 // eden top. (Need to set end because reset_after_change() mangles the region
432 // from end to virtual_space->high() in debug builds).
433 HeapWord* const new_top = eden_space->top();
434 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
435 absorb_size);
436 young_gen->reset_after_change();
437 old_space->set_top(new_top);
438 old_space->set_end(new_top);
439 old_gen->reset_after_change();
440
441 // Update the object start array for the filler object and the data from eden.
442 ObjectStartArray* const start_array = old_gen->start_array();
443 HeapWord* const start = old_gen_unused.start();
444 for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) {
445 start_array->allocate_block(addr);
446 }
447
448 // Could update the promoted average here, but it is not typically updated at
449 // full GCs and the value to use is unclear. Something like
450 //
451 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
452
453 size_policy->set_bytes_absorbed_from_eden(absorb_size);
454 return true;
455 }
456
457 void PSMarkSweep::allocate_stacks() {
458 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
459 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
460
461 PSYoungGen* young_gen = heap->young_gen();
462
463 MutableSpace* to_space = young_gen->to_space();
464 _preserved_marks = (PreservedMark*)to_space->top();
465 _preserved_count = 0;
466
467 // We want to calculate the size in bytes first.
468 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
469 // Now divide by the size of a PreservedMark
470 _preserved_count_max /= sizeof(PreservedMark);
471
472 _preserved_mark_stack = NULL;
473 _preserved_oop_stack = NULL;
474
475 _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
476
477 int size = SystemDictionary::number_of_classes() * 2;
478 _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
479 }
480
481
482 void PSMarkSweep::deallocate_stacks() {
483 if (_preserved_oop_stack) {
484 delete _preserved_mark_stack;
485 _preserved_mark_stack = NULL;
486 delete _preserved_oop_stack;
487 _preserved_oop_stack = NULL;
488 }
489
490 delete _marking_stack;
491 delete _revisit_klass_stack;
492 }
493
494 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
495 // Recursively traverse all live objects and mark them
496 EventMark m("1 mark object");
497 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty);
498 trace(" 1");
499
500 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
501 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
502
503 // General strong roots.
504 Universe::oops_do(mark_and_push_closure());
505 ReferenceProcessor::oops_do(mark_and_push_closure());
506 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
507 Threads::oops_do(mark_and_push_closure());
508 ObjectSynchronizer::oops_do(mark_and_push_closure());
509 FlatProfiler::oops_do(mark_and_push_closure());
510 Management::oops_do(mark_and_push_closure());
511 JvmtiExport::oops_do(mark_and_push_closure());
512 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
513 vmSymbols::oops_do(mark_and_push_closure());
514
515 // Flush marking stack.
516 follow_stack();
517
518 // Process reference objects found during marking
519 {
520 ReferencePolicy *soft_ref_policy;
521 if (clear_all_softrefs) {
522 soft_ref_policy = new AlwaysClearPolicy();
523 } else {
524 #ifdef COMPILER2
525 soft_ref_policy = new LRUMaxHeapPolicy();
526 #else
527 soft_ref_policy = new LRUCurrentHeapPolicy();
528 #endif // COMPILER2
529 }
530 assert(soft_ref_policy != NULL,"No soft reference policy");
531 ref_processor()->process_discovered_references(
532 soft_ref_policy, is_alive_closure(), mark_and_push_closure(),
533 follow_stack_closure(), NULL);
534 }
535
536 // Follow system dictionary roots and unload classes
537 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
538
539 // Follow code cache roots
540 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(),
541 purged_class);
542 follow_stack(); // Flush marking stack
543
544 // Update subklass/sibling/implementor links of live klasses
545 follow_weak_klass_links();
546 assert(_marking_stack->is_empty(), "just drained");
547
548 // Visit symbol and interned string tables and delete unmarked oops
549 SymbolTable::unlink(is_alive_closure());
550 StringTable::unlink(is_alive_closure());
551
552 assert(_marking_stack->is_empty(), "stack should be empty by now");
553 }
554
555
556 void PSMarkSweep::mark_sweep_phase2() {
557 EventMark m("2 compute new addresses");
558 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty);
559 trace("2");
560
561 // Now all live objects are marked, compute the new object addresses.
562
563 // It is imperative that we traverse perm_gen LAST. If dead space is
564 // allowed a range of dead object may get overwritten by a dead int
565 // array. If perm_gen is not traversed last a klassOop may get
566 // overwritten. This is fine since it is dead, but if the class has dead
567 // instances we have to skip them, and in order to find their size we
568 // need the klassOop!
569 //
570 // It is not required that we traverse spaces in the same order in
571 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
572 // tracking expects us to do so. See comment under phase4.
573
574 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
575 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
576
577 PSOldGen* old_gen = heap->old_gen();
578 PSPermGen* perm_gen = heap->perm_gen();
579
580 // Begin compacting into the old gen
581 PSMarkSweepDecorator::set_destination_decorator_tenured();
582
583 // This will also compact the young gen spaces.
584 old_gen->precompact();
585
586 // Compact the perm gen into the perm gen
587 PSMarkSweepDecorator::set_destination_decorator_perm_gen();
588
589 perm_gen->precompact();
590 }
591
592 // This should be moved to the shared markSweep code!
593 class PSAlwaysTrueClosure: public BoolObjectClosure {
594 public:
595 void do_object(oop p) { ShouldNotReachHere(); }
596 bool do_object_b(oop p) { return true; }
597 };
598 static PSAlwaysTrueClosure always_true;
599
600 void PSMarkSweep::mark_sweep_phase3() {
601 // Adjust the pointers to reflect the new locations
602 EventMark m("3 adjust pointers");
603 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty);
604 trace("3");
605
606 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
607 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
608
609 PSYoungGen* young_gen = heap->young_gen();
610 PSOldGen* old_gen = heap->old_gen();
611 PSPermGen* perm_gen = heap->perm_gen();
612
613 // General strong roots.
614 Universe::oops_do(adjust_root_pointer_closure());
615 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
616 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
617 Threads::oops_do(adjust_root_pointer_closure());
618 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
619 FlatProfiler::oops_do(adjust_root_pointer_closure());
620 Management::oops_do(adjust_root_pointer_closure());
621 JvmtiExport::oops_do(adjust_root_pointer_closure());
622 // SO_AllClasses
623 SystemDictionary::oops_do(adjust_root_pointer_closure());
624 vmSymbols::oops_do(adjust_root_pointer_closure());
625
626 // Now adjust pointers in remaining weak roots. (All of which should
627 // have been cleared if they pointed to non-surviving objects.)
628 // Global (weak) JNI handles
629 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
630
631 CodeCache::oops_do(adjust_pointer_closure());
632 SymbolTable::oops_do(adjust_root_pointer_closure());
633 StringTable::oops_do(adjust_root_pointer_closure());
634 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
635 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure());
636
637 adjust_marks();
638
639 young_gen->adjust_pointers();
640 old_gen->adjust_pointers();
641 perm_gen->adjust_pointers();
642 }
643
644 void PSMarkSweep::mark_sweep_phase4() {
645 EventMark m("4 compact heap");
646 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty);
647 trace("4");
648
649 // All pointers are now adjusted, move objects accordingly
650
651 // It is imperative that we traverse perm_gen first in phase4. All
652 // classes must be allocated earlier than their instances, and traversing
653 // perm_gen first makes sure that all klassOops have moved to their new
654 // location before any instance does a dispatch through it's klass!
655 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
656 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
657
658 PSYoungGen* young_gen = heap->young_gen();
659 PSOldGen* old_gen = heap->old_gen();
660 PSPermGen* perm_gen = heap->perm_gen();
661
662 perm_gen->compact();
663 old_gen->compact();
664 young_gen->compact();
665 }
666
667 jlong PSMarkSweep::millis_since_last_gc() {
668 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
669 // XXX See note in genCollectedHeap::millis_since_last_gc().
670 if (ret_val < 0) {
671 NOT_PRODUCT(warning("time warp: %d", ret_val);)
672 return 0;
673 }
674 return ret_val;
675 }
676
677 void PSMarkSweep::reset_millis_since_last_gc() {
678 _time_of_last_gc = os::javaTimeMillis();
679 }