Mon, 28 Jul 2008 15:30:23 -0700
Merge
1 /*
2 * Copyright 2001-2007 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 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_psMarkSweep.cpp.incl"
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;
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 if (!UseParallelOldGC || !VerifyParallelOldWithMarkSweep) {
39 _counters = new CollectorCounters("PSMarkSweep", 1);
40 }
41 }
43 // This method contains all heap specific policy for invoking mark sweep.
44 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
45 // the heap. It will do nothing further. If we need to bail out for policy
46 // reasons, scavenge before full gc, or any other specialized behavior, it
47 // needs to be added here.
48 //
49 // Note that this method should only be called from the vm_thread while
50 // at a safepoint!
51 void PSMarkSweep::invoke(bool maximum_heap_compaction) {
52 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
53 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
54 assert(!Universe::heap()->is_gc_active(), "not reentrant");
56 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
57 GCCause::Cause gc_cause = heap->gc_cause();
58 PSAdaptiveSizePolicy* policy = heap->size_policy();
60 // Before each allocation/collection attempt, find out from the
61 // policy object if GCs are, on the whole, taking too long. If so,
62 // bail out without attempting a collection. The exceptions are
63 // for explicitly requested GC's.
64 if (!policy->gc_time_limit_exceeded() ||
65 GCCause::is_user_requested_gc(gc_cause) ||
66 GCCause::is_serviceability_requested_gc(gc_cause)) {
67 IsGCActiveMark mark;
69 if (ScavengeBeforeFullGC) {
70 PSScavenge::invoke_no_policy();
71 }
73 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount;
74 IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
75 PSMarkSweep::invoke_no_policy(maximum_heap_compaction);
76 }
77 }
79 // This method contains no policy. You should probably
80 // be calling invoke() instead.
81 void PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
82 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
83 assert(ref_processor() != NULL, "Sanity");
85 if (GC_locker::check_active_before_gc()) {
86 return;
87 }
89 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
90 GCCause::Cause gc_cause = heap->gc_cause();
91 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
92 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
94 PSYoungGen* young_gen = heap->young_gen();
95 PSOldGen* old_gen = heap->old_gen();
96 PSPermGen* perm_gen = heap->perm_gen();
98 // Increment the invocation count
99 heap->increment_total_collections(true /* full */);
101 // Save information needed to minimize mangling
102 heap->record_gen_tops_before_GC();
104 // We need to track unique mark sweep invocations as well.
105 _total_invocations++;
107 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
109 if (PrintHeapAtGC) {
110 Universe::print_heap_before_gc();
111 }
113 // Fill in TLABs
114 heap->accumulate_statistics_all_tlabs();
115 heap->ensure_parsability(true); // retire TLABs
117 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
118 HandleMark hm; // Discard invalid handles created during verification
119 gclog_or_tty->print(" VerifyBeforeGC:");
120 Universe::verify(true);
121 }
123 // Verify object start arrays
124 if (VerifyObjectStartArray &&
125 VerifyBeforeGC) {
126 old_gen->verify_object_start_array();
127 perm_gen->verify_object_start_array();
128 }
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;
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 */);
150 if (TraceGen1Time) accumulated_time()->start();
152 // Let the size policy know we're starting
153 size_policy->major_collection_begin();
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();
161 // Capture heap size before collection for printing.
162 size_t prev_used = heap->used();
164 // Capture perm gen size before collection for sizing.
165 size_t perm_gen_prev_used = perm_gen->used_in_bytes();
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();
171 allocate_stacks();
173 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
174 COMPILER2_PRESENT(DerivedPointerTable::clear());
176 ref_processor()->enable_discovery();
178 mark_sweep_phase1(clear_all_softrefs);
180 mark_sweep_phase2();
182 // Don't add any more derived pointers during phase3
183 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
184 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
186 mark_sweep_phase3();
188 mark_sweep_phase4();
190 restore_marks();
192 deallocate_stacks();
194 if (ZapUnusedHeapArea) {
195 // Do a complete mangle (top to end) because the usage for
196 // scratch does not maintain a top pointer.
197 young_gen->to_space()->mangle_unused_area_complete();
198 }
200 eden_empty = young_gen->eden_space()->is_empty();
201 if (!eden_empty) {
202 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
203 }
205 // Update heap occupancy information which is used as
206 // input to soft ref clearing policy at the next gc.
207 Universe::update_heap_info_at_gc();
209 survivors_empty = young_gen->from_space()->is_empty() &&
210 young_gen->to_space()->is_empty();
211 young_gen_empty = eden_empty && survivors_empty;
213 BarrierSet* bs = heap->barrier_set();
214 if (bs->is_a(BarrierSet::ModRef)) {
215 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
216 MemRegion old_mr = heap->old_gen()->reserved();
217 MemRegion perm_mr = heap->perm_gen()->reserved();
218 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
220 if (young_gen_empty) {
221 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
222 } else {
223 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
224 }
225 }
227 BiasedLocking::restore_marks();
228 Threads::gc_epilogue();
229 CodeCache::gc_epilogue();
231 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
233 ref_processor()->enqueue_discovered_references(NULL);
235 // Update time of last GC
236 reset_millis_since_last_gc();
238 // Let the size policy know we're done
239 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
241 if (UseAdaptiveSizePolicy) {
243 if (PrintAdaptiveSizePolicy) {
244 gclog_or_tty->print("AdaptiveSizeStart: ");
245 gclog_or_tty->stamp();
246 gclog_or_tty->print_cr(" collection: %d ",
247 heap->total_collections());
248 if (Verbose) {
249 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
250 " perm_gen_capacity: %d ",
251 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
252 perm_gen->capacity_in_bytes());
253 }
254 }
256 // Don't check if the size_policy is ready here. Let
257 // the size_policy check that internally.
258 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
259 ((gc_cause != GCCause::_java_lang_system_gc) ||
260 UseAdaptiveSizePolicyWithSystemGC)) {
261 // Calculate optimal free space amounts
262 assert(young_gen->max_size() >
263 young_gen->from_space()->capacity_in_bytes() +
264 young_gen->to_space()->capacity_in_bytes(),
265 "Sizes of space in young gen are out-of-bounds");
266 size_t max_eden_size = young_gen->max_size() -
267 young_gen->from_space()->capacity_in_bytes() -
268 young_gen->to_space()->capacity_in_bytes();
269 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
270 young_gen->eden_space()->used_in_bytes(),
271 old_gen->used_in_bytes(),
272 perm_gen->used_in_bytes(),
273 young_gen->eden_space()->capacity_in_bytes(),
274 old_gen->max_gen_size(),
275 max_eden_size,
276 true /* full gc*/,
277 gc_cause);
279 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
281 // Don't resize the young generation at an major collection. A
282 // desired young generation size may have been calculated but
283 // resizing the young generation complicates the code because the
284 // resizing of the old generation may have moved the boundary
285 // between the young generation and the old generation. Let the
286 // young generation resizing happen at the minor collections.
287 }
288 if (PrintAdaptiveSizePolicy) {
289 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
290 heap->total_collections());
291 }
292 }
294 if (UsePerfData) {
295 heap->gc_policy_counters()->update_counters();
296 heap->gc_policy_counters()->update_old_capacity(
297 old_gen->capacity_in_bytes());
298 heap->gc_policy_counters()->update_young_capacity(
299 young_gen->capacity_in_bytes());
300 }
302 heap->resize_all_tlabs();
304 // We collected the perm gen, so we'll resize it here.
305 perm_gen->compute_new_size(perm_gen_prev_used);
307 if (TraceGen1Time) accumulated_time()->stop();
309 if (PrintGC) {
310 if (PrintGCDetails) {
311 // Don't print a GC timestamp here. This is after the GC so
312 // would be confusing.
313 young_gen->print_used_change(young_gen_prev_used);
314 old_gen->print_used_change(old_gen_prev_used);
315 }
316 heap->print_heap_change(prev_used);
317 // Do perm gen after heap becase prev_used does
318 // not include the perm gen (done this way in the other
319 // collectors).
320 if (PrintGCDetails) {
321 perm_gen->print_used_change(perm_gen_prev_used);
322 }
323 }
325 // Track memory usage and detect low memory
326 MemoryService::track_memory_usage();
327 heap->update_counters();
329 if (PrintGCDetails) {
330 if (size_policy->print_gc_time_limit_would_be_exceeded()) {
331 if (size_policy->gc_time_limit_exceeded()) {
332 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit "
333 "of %d%%", GCTimeLimit);
334 } else {
335 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit "
336 "of %d%%", GCTimeLimit);
337 }
338 }
339 size_policy->set_print_gc_time_limit_would_be_exceeded(false);
340 }
341 }
343 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
344 HandleMark hm; // Discard invalid handles created during verification
345 gclog_or_tty->print(" VerifyAfterGC:");
346 Universe::verify(false);
347 }
349 // Re-verify object start arrays
350 if (VerifyObjectStartArray &&
351 VerifyAfterGC) {
352 old_gen->verify_object_start_array();
353 perm_gen->verify_object_start_array();
354 }
356 if (ZapUnusedHeapArea) {
357 old_gen->object_space()->check_mangled_unused_area_complete();
358 perm_gen->object_space()->check_mangled_unused_area_complete();
359 }
361 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
363 if (PrintHeapAtGC) {
364 Universe::print_heap_after_gc();
365 }
366 }
368 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
369 PSYoungGen* young_gen,
370 PSOldGen* old_gen) {
371 MutableSpace* const eden_space = young_gen->eden_space();
372 assert(!eden_space->is_empty(), "eden must be non-empty");
373 assert(young_gen->virtual_space()->alignment() ==
374 old_gen->virtual_space()->alignment(), "alignments do not match");
376 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
377 return false;
378 }
380 // Both generations must be completely committed.
381 if (young_gen->virtual_space()->uncommitted_size() != 0) {
382 return false;
383 }
384 if (old_gen->virtual_space()->uncommitted_size() != 0) {
385 return false;
386 }
388 // Figure out how much to take from eden. Include the average amount promoted
389 // in the total; otherwise the next young gen GC will simply bail out to a
390 // full GC.
391 const size_t alignment = old_gen->virtual_space()->alignment();
392 const size_t eden_used = eden_space->used_in_bytes();
393 const size_t promoted = (size_t)(size_policy->avg_promoted()->padded_average());
394 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
395 const size_t eden_capacity = eden_space->capacity_in_bytes();
397 if (absorb_size >= eden_capacity) {
398 return false; // Must leave some space in eden.
399 }
401 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
402 if (new_young_size < young_gen->min_gen_size()) {
403 return false; // Respect young gen minimum size.
404 }
406 if (TraceAdaptiveGCBoundary && Verbose) {
407 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
408 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
409 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
410 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
411 absorb_size / K,
412 eden_capacity / K, (eden_capacity - absorb_size) / K,
413 young_gen->from_space()->used_in_bytes() / K,
414 young_gen->to_space()->used_in_bytes() / K,
415 young_gen->capacity_in_bytes() / K, new_young_size / K);
416 }
418 // Fill the unused part of the old gen.
419 MutableSpace* const old_space = old_gen->object_space();
420 MemRegion old_gen_unused(old_space->top(), old_space->end());
422 // If the unused part of the old gen cannot be filled, skip
423 // absorbing eden.
424 if (old_gen_unused.word_size() < SharedHeap::min_fill_size()) {
425 return false;
426 }
428 if (!old_gen_unused.is_empty()) {
429 SharedHeap::fill_region_with_object(old_gen_unused);
430 }
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();
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 HeapWord* const start = old_gen_unused.start();
446 for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) {
447 start_array->allocate_block(addr);
448 }
450 // Could update the promoted average here, but it is not typically updated at
451 // full GCs and the value to use is unclear. Something like
452 //
453 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
455 size_policy->set_bytes_absorbed_from_eden(absorb_size);
456 return true;
457 }
459 void PSMarkSweep::allocate_stacks() {
460 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
461 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
463 PSYoungGen* young_gen = heap->young_gen();
465 MutableSpace* to_space = young_gen->to_space();
466 _preserved_marks = (PreservedMark*)to_space->top();
467 _preserved_count = 0;
469 // We want to calculate the size in bytes first.
470 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
471 // Now divide by the size of a PreservedMark
472 _preserved_count_max /= sizeof(PreservedMark);
474 _preserved_mark_stack = NULL;
475 _preserved_oop_stack = NULL;
477 _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
479 int size = SystemDictionary::number_of_classes() * 2;
480 _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
481 }
484 void PSMarkSweep::deallocate_stacks() {
485 if (_preserved_oop_stack) {
486 delete _preserved_mark_stack;
487 _preserved_mark_stack = NULL;
488 delete _preserved_oop_stack;
489 _preserved_oop_stack = NULL;
490 }
492 delete _marking_stack;
493 delete _revisit_klass_stack;
494 }
496 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
497 // Recursively traverse all live objects and mark them
498 EventMark m("1 mark object");
499 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty);
500 trace(" 1");
502 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
503 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
505 // General strong roots.
506 Universe::oops_do(mark_and_push_closure());
507 ReferenceProcessor::oops_do(mark_and_push_closure());
508 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles
509 Threads::oops_do(mark_and_push_closure());
510 ObjectSynchronizer::oops_do(mark_and_push_closure());
511 FlatProfiler::oops_do(mark_and_push_closure());
512 Management::oops_do(mark_and_push_closure());
513 JvmtiExport::oops_do(mark_and_push_closure());
514 SystemDictionary::always_strong_oops_do(mark_and_push_closure());
515 vmSymbols::oops_do(mark_and_push_closure());
517 // Flush marking stack.
518 follow_stack();
520 // Process reference objects found during marking
522 // Skipping the reference processing for VerifyParallelOldWithMarkSweep
523 // affects the marking (makes it different).
524 {
525 ReferencePolicy *soft_ref_policy;
526 if (clear_all_softrefs) {
527 soft_ref_policy = new AlwaysClearPolicy();
528 } else {
529 #ifdef COMPILER2
530 soft_ref_policy = new LRUMaxHeapPolicy();
531 #else
532 soft_ref_policy = new LRUCurrentHeapPolicy();
533 #endif // COMPILER2
534 }
535 assert(soft_ref_policy != NULL,"No soft reference policy");
536 ref_processor()->process_discovered_references(
537 soft_ref_policy, is_alive_closure(), mark_and_push_closure(),
538 follow_stack_closure(), NULL);
539 }
541 // Follow system dictionary roots and unload classes
542 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
544 // Follow code cache roots
545 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(),
546 purged_class);
547 follow_stack(); // Flush marking stack
549 // Update subklass/sibling/implementor links of live klasses
550 follow_weak_klass_links();
551 assert(_marking_stack->is_empty(), "just drained");
553 // Visit symbol and interned string tables and delete unmarked oops
554 SymbolTable::unlink(is_alive_closure());
555 StringTable::unlink(is_alive_closure());
557 assert(_marking_stack->is_empty(), "stack should be empty by now");
558 }
561 void PSMarkSweep::mark_sweep_phase2() {
562 EventMark m("2 compute new addresses");
563 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty);
564 trace("2");
566 // Now all live objects are marked, compute the new object addresses.
568 // It is imperative that we traverse perm_gen LAST. If dead space is
569 // allowed a range of dead object may get overwritten by a dead int
570 // array. If perm_gen is not traversed last a klassOop may get
571 // overwritten. This is fine since it is dead, but if the class has dead
572 // instances we have to skip them, and in order to find their size we
573 // need the klassOop!
574 //
575 // It is not required that we traverse spaces in the same order in
576 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
577 // tracking expects us to do so. See comment under phase4.
579 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
580 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
582 PSOldGen* old_gen = heap->old_gen();
583 PSPermGen* perm_gen = heap->perm_gen();
585 // Begin compacting into the old gen
586 PSMarkSweepDecorator::set_destination_decorator_tenured();
588 // This will also compact the young gen spaces.
589 old_gen->precompact();
591 // Compact the perm gen into the perm gen
592 PSMarkSweepDecorator::set_destination_decorator_perm_gen();
594 perm_gen->precompact();
595 }
597 // This should be moved to the shared markSweep code!
598 class PSAlwaysTrueClosure: public BoolObjectClosure {
599 public:
600 void do_object(oop p) { ShouldNotReachHere(); }
601 bool do_object_b(oop p) { return true; }
602 };
603 static PSAlwaysTrueClosure always_true;
605 void PSMarkSweep::mark_sweep_phase3() {
606 // Adjust the pointers to reflect the new locations
607 EventMark m("3 adjust pointers");
608 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty);
609 trace("3");
611 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
612 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
614 PSYoungGen* young_gen = heap->young_gen();
615 PSOldGen* old_gen = heap->old_gen();
616 PSPermGen* perm_gen = heap->perm_gen();
618 // General strong roots.
619 Universe::oops_do(adjust_root_pointer_closure());
620 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
621 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
622 Threads::oops_do(adjust_root_pointer_closure());
623 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
624 FlatProfiler::oops_do(adjust_root_pointer_closure());
625 Management::oops_do(adjust_root_pointer_closure());
626 JvmtiExport::oops_do(adjust_root_pointer_closure());
627 // SO_AllClasses
628 SystemDictionary::oops_do(adjust_root_pointer_closure());
629 vmSymbols::oops_do(adjust_root_pointer_closure());
631 // Now adjust pointers in remaining weak roots. (All of which should
632 // have been cleared if they pointed to non-surviving objects.)
633 // Global (weak) JNI handles
634 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
636 CodeCache::oops_do(adjust_pointer_closure());
637 SymbolTable::oops_do(adjust_root_pointer_closure());
638 StringTable::oops_do(adjust_root_pointer_closure());
639 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
640 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure());
642 adjust_marks();
644 young_gen->adjust_pointers();
645 old_gen->adjust_pointers();
646 perm_gen->adjust_pointers();
647 }
649 void PSMarkSweep::mark_sweep_phase4() {
650 EventMark m("4 compact heap");
651 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty);
652 trace("4");
654 // All pointers are now adjusted, move objects accordingly
656 // It is imperative that we traverse perm_gen first in phase4. All
657 // classes must be allocated earlier than their instances, and traversing
658 // perm_gen first makes sure that all klassOops have moved to their new
659 // location before any instance does a dispatch through it's klass!
660 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
661 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
663 PSYoungGen* young_gen = heap->young_gen();
664 PSOldGen* old_gen = heap->old_gen();
665 PSPermGen* perm_gen = heap->perm_gen();
667 perm_gen->compact();
668 old_gen->compact();
669 young_gen->compact();
670 }
672 jlong PSMarkSweep::millis_since_last_gc() {
673 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
674 // XXX See note in genCollectedHeap::millis_since_last_gc().
675 if (ret_val < 0) {
676 NOT_PRODUCT(warning("time warp: %d", ret_val);)
677 return 0;
678 }
679 return ret_val;
680 }
682 void PSMarkSweep::reset_millis_since_last_gc() {
683 _time_of_last_gc = os::javaTimeMillis();
684 }