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comparison src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 12eea04c8b06 |
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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 */ | |
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 if (!UseParallelOldGC || !VerifyParallelOldWithMarkSweep) { | |
39 _counters = new CollectorCounters("PSMarkSweep", 1); | |
40 } | |
41 } | |
42 | |
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"); | |
55 | |
56 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
57 GCCause::Cause gc_cause = heap->gc_cause(); | |
58 PSAdaptiveSizePolicy* policy = heap->size_policy(); | |
59 | |
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; | |
68 | |
69 if (ScavengeBeforeFullGC) { | |
70 PSScavenge::invoke_no_policy(); | |
71 } | |
72 | |
73 int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount; | |
74 IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); | |
75 PSMarkSweep::invoke_no_policy(maximum_heap_compaction); | |
76 } | |
77 } | |
78 | |
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"); | |
84 | |
85 if (GC_locker::check_active_before_gc()) { | |
86 return; | |
87 } | |
88 | |
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(); | |
93 | |
94 PSYoungGen* young_gen = heap->young_gen(); | |
95 PSOldGen* old_gen = heap->old_gen(); | |
96 PSPermGen* perm_gen = heap->perm_gen(); | |
97 | |
98 // Increment the invocation count | |
99 heap->increment_total_collections(true /* full */); | |
100 | |
101 // We need to track unique mark sweep invocations as well. | |
102 _total_invocations++; | |
103 | |
104 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); | |
105 | |
106 if (PrintHeapAtGC) { | |
107 Universe::print_heap_before_gc(); | |
108 } | |
109 | |
110 // Fill in TLABs | |
111 heap->accumulate_statistics_all_tlabs(); | |
112 heap->ensure_parsability(true); // retire TLABs | |
113 | |
114 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { | |
115 HandleMark hm; // Discard invalid handles created during verification | |
116 gclog_or_tty->print(" VerifyBeforeGC:"); | |
117 Universe::verify(true); | |
118 } | |
119 | |
120 // Verify object start arrays | |
121 if (VerifyObjectStartArray && | |
122 VerifyBeforeGC) { | |
123 old_gen->verify_object_start_array(); | |
124 perm_gen->verify_object_start_array(); | |
125 } | |
126 | |
127 // Filled in below to track the state of the young gen after the collection. | |
128 bool eden_empty; | |
129 bool survivors_empty; | |
130 bool young_gen_empty; | |
131 | |
132 { | |
133 HandleMark hm; | |
134 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc; | |
135 // This is useful for debugging but don't change the output the | |
136 // the customer sees. | |
137 const char* gc_cause_str = "Full GC"; | |
138 if (is_system_gc && PrintGCDetails) { | |
139 gc_cause_str = "Full GC (System)"; | |
140 } | |
141 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); | |
142 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); | |
143 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty); | |
144 TraceCollectorStats tcs(counters()); | |
145 TraceMemoryManagerStats tms(true /* Full GC */); | |
146 | |
147 if (TraceGen1Time) accumulated_time()->start(); | |
148 | |
149 // Let the size policy know we're starting | |
150 size_policy->major_collection_begin(); | |
151 | |
152 // When collecting the permanent generation methodOops may be moving, | |
153 // so we either have to flush all bcp data or convert it into bci. | |
154 CodeCache::gc_prologue(); | |
155 Threads::gc_prologue(); | |
156 BiasedLocking::preserve_marks(); | |
157 | |
158 // Capture heap size before collection for printing. | |
159 size_t prev_used = heap->used(); | |
160 | |
161 // Capture perm gen size before collection for sizing. | |
162 size_t perm_gen_prev_used = perm_gen->used_in_bytes(); | |
163 | |
164 // For PrintGCDetails | |
165 size_t old_gen_prev_used = old_gen->used_in_bytes(); | |
166 size_t young_gen_prev_used = young_gen->used_in_bytes(); | |
167 | |
168 allocate_stacks(); | |
169 | |
170 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); | |
171 COMPILER2_PRESENT(DerivedPointerTable::clear()); | |
172 | |
173 ref_processor()->enable_discovery(); | |
174 | |
175 mark_sweep_phase1(clear_all_softrefs); | |
176 | |
177 mark_sweep_phase2(); | |
178 | |
179 // Don't add any more derived pointers during phase3 | |
180 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); | |
181 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); | |
182 | |
183 mark_sweep_phase3(); | |
184 | |
185 mark_sweep_phase4(); | |
186 | |
187 restore_marks(); | |
188 | |
189 deallocate_stacks(); | |
190 | |
191 eden_empty = young_gen->eden_space()->is_empty(); | |
192 if (!eden_empty) { | |
193 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); | |
194 } | |
195 | |
196 // Update heap occupancy information which is used as | |
197 // input to soft ref clearing policy at the next gc. | |
198 Universe::update_heap_info_at_gc(); | |
199 | |
200 survivors_empty = young_gen->from_space()->is_empty() && | |
201 young_gen->to_space()->is_empty(); | |
202 young_gen_empty = eden_empty && survivors_empty; | |
203 | |
204 BarrierSet* bs = heap->barrier_set(); | |
205 if (bs->is_a(BarrierSet::ModRef)) { | |
206 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs; | |
207 MemRegion old_mr = heap->old_gen()->reserved(); | |
208 MemRegion perm_mr = heap->perm_gen()->reserved(); | |
209 assert(perm_mr.end() <= old_mr.start(), "Generations out of order"); | |
210 | |
211 if (young_gen_empty) { | |
212 modBS->clear(MemRegion(perm_mr.start(), old_mr.end())); | |
213 } else { | |
214 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end())); | |
215 } | |
216 } | |
217 | |
218 BiasedLocking::restore_marks(); | |
219 Threads::gc_epilogue(); | |
220 CodeCache::gc_epilogue(); | |
221 | |
222 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); | |
223 | |
224 ref_processor()->enqueue_discovered_references(NULL); | |
225 | |
226 // Update time of last GC | |
227 reset_millis_since_last_gc(); | |
228 | |
229 // Let the size policy know we're done | |
230 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); | |
231 | |
232 if (UseAdaptiveSizePolicy) { | |
233 | |
234 if (PrintAdaptiveSizePolicy) { | |
235 gclog_or_tty->print("AdaptiveSizeStart: "); | |
236 gclog_or_tty->stamp(); | |
237 gclog_or_tty->print_cr(" collection: %d ", | |
238 heap->total_collections()); | |
239 if (Verbose) { | |
240 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" | |
241 " perm_gen_capacity: %d ", | |
242 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), | |
243 perm_gen->capacity_in_bytes()); | |
244 } | |
245 } | |
246 | |
247 // Don't check if the size_policy is ready here. Let | |
248 // the size_policy check that internally. | |
249 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && | |
250 ((gc_cause != GCCause::_java_lang_system_gc) || | |
251 UseAdaptiveSizePolicyWithSystemGC)) { | |
252 // Calculate optimal free space amounts | |
253 assert(young_gen->max_size() > | |
254 young_gen->from_space()->capacity_in_bytes() + | |
255 young_gen->to_space()->capacity_in_bytes(), | |
256 "Sizes of space in young gen are out-of-bounds"); | |
257 size_t max_eden_size = young_gen->max_size() - | |
258 young_gen->from_space()->capacity_in_bytes() - | |
259 young_gen->to_space()->capacity_in_bytes(); | |
260 size_policy->compute_generation_free_space(young_gen->used_in_bytes(), | |
261 young_gen->eden_space()->used_in_bytes(), | |
262 old_gen->used_in_bytes(), | |
263 perm_gen->used_in_bytes(), | |
264 young_gen->eden_space()->capacity_in_bytes(), | |
265 old_gen->max_gen_size(), | |
266 max_eden_size, | |
267 true /* full gc*/, | |
268 gc_cause); | |
269 | |
270 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); | |
271 | |
272 // Don't resize the young generation at an major collection. A | |
273 // desired young generation size may have been calculated but | |
274 // resizing the young generation complicates the code because the | |
275 // resizing of the old generation may have moved the boundary | |
276 // between the young generation and the old generation. Let the | |
277 // young generation resizing happen at the minor collections. | |
278 } | |
279 if (PrintAdaptiveSizePolicy) { | |
280 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", | |
281 heap->total_collections()); | |
282 } | |
283 } | |
284 | |
285 if (UsePerfData) { | |
286 heap->gc_policy_counters()->update_counters(); | |
287 heap->gc_policy_counters()->update_old_capacity( | |
288 old_gen->capacity_in_bytes()); | |
289 heap->gc_policy_counters()->update_young_capacity( | |
290 young_gen->capacity_in_bytes()); | |
291 } | |
292 | |
293 heap->resize_all_tlabs(); | |
294 | |
295 // We collected the perm gen, so we'll resize it here. | |
296 perm_gen->compute_new_size(perm_gen_prev_used); | |
297 | |
298 if (TraceGen1Time) accumulated_time()->stop(); | |
299 | |
300 if (PrintGC) { | |
301 if (PrintGCDetails) { | |
302 // Don't print a GC timestamp here. This is after the GC so | |
303 // would be confusing. | |
304 young_gen->print_used_change(young_gen_prev_used); | |
305 old_gen->print_used_change(old_gen_prev_used); | |
306 } | |
307 heap->print_heap_change(prev_used); | |
308 // Do perm gen after heap becase prev_used does | |
309 // not include the perm gen (done this way in the other | |
310 // collectors). | |
311 if (PrintGCDetails) { | |
312 perm_gen->print_used_change(perm_gen_prev_used); | |
313 } | |
314 } | |
315 | |
316 // Track memory usage and detect low memory | |
317 MemoryService::track_memory_usage(); | |
318 heap->update_counters(); | |
319 | |
320 if (PrintGCDetails) { | |
321 if (size_policy->print_gc_time_limit_would_be_exceeded()) { | |
322 if (size_policy->gc_time_limit_exceeded()) { | |
323 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit " | |
324 "of %d%%", GCTimeLimit); | |
325 } else { | |
326 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit " | |
327 "of %d%%", GCTimeLimit); | |
328 } | |
329 } | |
330 size_policy->set_print_gc_time_limit_would_be_exceeded(false); | |
331 } | |
332 } | |
333 | |
334 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { | |
335 HandleMark hm; // Discard invalid handles created during verification | |
336 gclog_or_tty->print(" VerifyAfterGC:"); | |
337 Universe::verify(false); | |
338 } | |
339 | |
340 // Re-verify object start arrays | |
341 if (VerifyObjectStartArray && | |
342 VerifyAfterGC) { | |
343 old_gen->verify_object_start_array(); | |
344 perm_gen->verify_object_start_array(); | |
345 } | |
346 | |
347 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); | |
348 | |
349 if (PrintHeapAtGC) { | |
350 Universe::print_heap_after_gc(); | |
351 } | |
352 } | |
353 | |
354 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, | |
355 PSYoungGen* young_gen, | |
356 PSOldGen* old_gen) { | |
357 MutableSpace* const eden_space = young_gen->eden_space(); | |
358 assert(!eden_space->is_empty(), "eden must be non-empty"); | |
359 assert(young_gen->virtual_space()->alignment() == | |
360 old_gen->virtual_space()->alignment(), "alignments do not match"); | |
361 | |
362 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { | |
363 return false; | |
364 } | |
365 | |
366 // Both generations must be completely committed. | |
367 if (young_gen->virtual_space()->uncommitted_size() != 0) { | |
368 return false; | |
369 } | |
370 if (old_gen->virtual_space()->uncommitted_size() != 0) { | |
371 return false; | |
372 } | |
373 | |
374 // Figure out how much to take from eden. Include the average amount promoted | |
375 // in the total; otherwise the next young gen GC will simply bail out to a | |
376 // full GC. | |
377 const size_t alignment = old_gen->virtual_space()->alignment(); | |
378 const size_t eden_used = eden_space->used_in_bytes(); | |
379 const size_t promoted = (size_t)(size_policy->avg_promoted()->padded_average()); | |
380 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); | |
381 const size_t eden_capacity = eden_space->capacity_in_bytes(); | |
382 | |
383 if (absorb_size >= eden_capacity) { | |
384 return false; // Must leave some space in eden. | |
385 } | |
386 | |
387 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; | |
388 if (new_young_size < young_gen->min_gen_size()) { | |
389 return false; // Respect young gen minimum size. | |
390 } | |
391 | |
392 if (TraceAdaptiveGCBoundary && Verbose) { | |
393 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: " | |
394 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " | |
395 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " | |
396 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", | |
397 absorb_size / K, | |
398 eden_capacity / K, (eden_capacity - absorb_size) / K, | |
399 young_gen->from_space()->used_in_bytes() / K, | |
400 young_gen->to_space()->used_in_bytes() / K, | |
401 young_gen->capacity_in_bytes() / K, new_young_size / K); | |
402 } | |
403 | |
404 // Fill the unused part of the old gen. | |
405 MutableSpace* const old_space = old_gen->object_space(); | |
406 MemRegion old_gen_unused(old_space->top(), old_space->end()); | |
407 | |
408 // If the unused part of the old gen cannot be filled, skip | |
409 // absorbing eden. | |
410 if (old_gen_unused.word_size() < SharedHeap::min_fill_size()) { | |
411 return false; | |
412 } | |
413 | |
414 if (!old_gen_unused.is_empty()) { | |
415 SharedHeap::fill_region_with_object(old_gen_unused); | |
416 } | |
417 | |
418 // Take the live data from eden and set both top and end in the old gen to | |
419 // eden top. (Need to set end because reset_after_change() mangles the region | |
420 // from end to virtual_space->high() in debug builds). | |
421 HeapWord* const new_top = eden_space->top(); | |
422 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), | |
423 absorb_size); | |
424 young_gen->reset_after_change(); | |
425 old_space->set_top(new_top); | |
426 old_space->set_end(new_top); | |
427 old_gen->reset_after_change(); | |
428 | |
429 // Update the object start array for the filler object and the data from eden. | |
430 ObjectStartArray* const start_array = old_gen->start_array(); | |
431 HeapWord* const start = old_gen_unused.start(); | |
432 for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) { | |
433 start_array->allocate_block(addr); | |
434 } | |
435 | |
436 // Could update the promoted average here, but it is not typically updated at | |
437 // full GCs and the value to use is unclear. Something like | |
438 // | |
439 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. | |
440 | |
441 size_policy->set_bytes_absorbed_from_eden(absorb_size); | |
442 return true; | |
443 } | |
444 | |
445 void PSMarkSweep::allocate_stacks() { | |
446 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
447 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
448 | |
449 PSYoungGen* young_gen = heap->young_gen(); | |
450 | |
451 MutableSpace* to_space = young_gen->to_space(); | |
452 _preserved_marks = (PreservedMark*)to_space->top(); | |
453 _preserved_count = 0; | |
454 | |
455 // We want to calculate the size in bytes first. | |
456 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); | |
457 // Now divide by the size of a PreservedMark | |
458 _preserved_count_max /= sizeof(PreservedMark); | |
459 | |
460 _preserved_mark_stack = NULL; | |
461 _preserved_oop_stack = NULL; | |
462 | |
463 _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true); | |
464 | |
465 int size = SystemDictionary::number_of_classes() * 2; | |
466 _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true); | |
467 } | |
468 | |
469 | |
470 void PSMarkSweep::deallocate_stacks() { | |
471 if (_preserved_oop_stack) { | |
472 delete _preserved_mark_stack; | |
473 _preserved_mark_stack = NULL; | |
474 delete _preserved_oop_stack; | |
475 _preserved_oop_stack = NULL; | |
476 } | |
477 | |
478 delete _marking_stack; | |
479 delete _revisit_klass_stack; | |
480 } | |
481 | |
482 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { | |
483 // Recursively traverse all live objects and mark them | |
484 EventMark m("1 mark object"); | |
485 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty); | |
486 trace(" 1"); | |
487 | |
488 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
489 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
490 | |
491 // General strong roots. | |
492 Universe::oops_do(mark_and_push_closure()); | |
493 ReferenceProcessor::oops_do(mark_and_push_closure()); | |
494 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles | |
495 Threads::oops_do(mark_and_push_closure()); | |
496 ObjectSynchronizer::oops_do(mark_and_push_closure()); | |
497 FlatProfiler::oops_do(mark_and_push_closure()); | |
498 Management::oops_do(mark_and_push_closure()); | |
499 JvmtiExport::oops_do(mark_and_push_closure()); | |
500 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); | |
501 vmSymbols::oops_do(mark_and_push_closure()); | |
502 | |
503 // Flush marking stack. | |
504 follow_stack(); | |
505 | |
506 // Process reference objects found during marking | |
507 | |
508 // Skipping the reference processing for VerifyParallelOldWithMarkSweep | |
509 // affects the marking (makes it different). | |
510 { | |
511 ReferencePolicy *soft_ref_policy; | |
512 if (clear_all_softrefs) { | |
513 soft_ref_policy = new AlwaysClearPolicy(); | |
514 } else { | |
515 #ifdef COMPILER2 | |
516 soft_ref_policy = new LRUMaxHeapPolicy(); | |
517 #else | |
518 soft_ref_policy = new LRUCurrentHeapPolicy(); | |
519 #endif // COMPILER2 | |
520 } | |
521 assert(soft_ref_policy != NULL,"No soft reference policy"); | |
522 ref_processor()->process_discovered_references( | |
523 soft_ref_policy, is_alive_closure(), mark_and_push_closure(), | |
524 follow_stack_closure(), NULL); | |
525 } | |
526 | |
527 // Follow system dictionary roots and unload classes | |
528 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); | |
529 | |
530 // Follow code cache roots | |
531 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(), | |
532 purged_class); | |
533 follow_stack(); // Flush marking stack | |
534 | |
535 // Update subklass/sibling/implementor links of live klasses | |
536 follow_weak_klass_links(); | |
537 assert(_marking_stack->is_empty(), "just drained"); | |
538 | |
539 // Visit symbol and interned string tables and delete unmarked oops | |
540 SymbolTable::unlink(is_alive_closure()); | |
541 StringTable::unlink(is_alive_closure()); | |
542 | |
543 assert(_marking_stack->is_empty(), "stack should be empty by now"); | |
544 } | |
545 | |
546 | |
547 void PSMarkSweep::mark_sweep_phase2() { | |
548 EventMark m("2 compute new addresses"); | |
549 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty); | |
550 trace("2"); | |
551 | |
552 // Now all live objects are marked, compute the new object addresses. | |
553 | |
554 // It is imperative that we traverse perm_gen LAST. If dead space is | |
555 // allowed a range of dead object may get overwritten by a dead int | |
556 // array. If perm_gen is not traversed last a klassOop may get | |
557 // overwritten. This is fine since it is dead, but if the class has dead | |
558 // instances we have to skip them, and in order to find their size we | |
559 // need the klassOop! | |
560 // | |
561 // It is not required that we traverse spaces in the same order in | |
562 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops | |
563 // tracking expects us to do so. See comment under phase4. | |
564 | |
565 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
566 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
567 | |
568 PSOldGen* old_gen = heap->old_gen(); | |
569 PSPermGen* perm_gen = heap->perm_gen(); | |
570 | |
571 // Begin compacting into the old gen | |
572 PSMarkSweepDecorator::set_destination_decorator_tenured(); | |
573 | |
574 // This will also compact the young gen spaces. | |
575 old_gen->precompact(); | |
576 | |
577 // Compact the perm gen into the perm gen | |
578 PSMarkSweepDecorator::set_destination_decorator_perm_gen(); | |
579 | |
580 perm_gen->precompact(); | |
581 } | |
582 | |
583 // This should be moved to the shared markSweep code! | |
584 class PSAlwaysTrueClosure: public BoolObjectClosure { | |
585 public: | |
586 void do_object(oop p) { ShouldNotReachHere(); } | |
587 bool do_object_b(oop p) { return true; } | |
588 }; | |
589 static PSAlwaysTrueClosure always_true; | |
590 | |
591 void PSMarkSweep::mark_sweep_phase3() { | |
592 // Adjust the pointers to reflect the new locations | |
593 EventMark m("3 adjust pointers"); | |
594 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty); | |
595 trace("3"); | |
596 | |
597 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
598 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
599 | |
600 PSYoungGen* young_gen = heap->young_gen(); | |
601 PSOldGen* old_gen = heap->old_gen(); | |
602 PSPermGen* perm_gen = heap->perm_gen(); | |
603 | |
604 // General strong roots. | |
605 Universe::oops_do(adjust_root_pointer_closure()); | |
606 ReferenceProcessor::oops_do(adjust_root_pointer_closure()); | |
607 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles | |
608 Threads::oops_do(adjust_root_pointer_closure()); | |
609 ObjectSynchronizer::oops_do(adjust_root_pointer_closure()); | |
610 FlatProfiler::oops_do(adjust_root_pointer_closure()); | |
611 Management::oops_do(adjust_root_pointer_closure()); | |
612 JvmtiExport::oops_do(adjust_root_pointer_closure()); | |
613 // SO_AllClasses | |
614 SystemDictionary::oops_do(adjust_root_pointer_closure()); | |
615 vmSymbols::oops_do(adjust_root_pointer_closure()); | |
616 | |
617 // Now adjust pointers in remaining weak roots. (All of which should | |
618 // have been cleared if they pointed to non-surviving objects.) | |
619 // Global (weak) JNI handles | |
620 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure()); | |
621 | |
622 CodeCache::oops_do(adjust_pointer_closure()); | |
623 SymbolTable::oops_do(adjust_root_pointer_closure()); | |
624 StringTable::oops_do(adjust_root_pointer_closure()); | |
625 ref_processor()->weak_oops_do(adjust_root_pointer_closure()); | |
626 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure()); | |
627 | |
628 adjust_marks(); | |
629 | |
630 young_gen->adjust_pointers(); | |
631 old_gen->adjust_pointers(); | |
632 perm_gen->adjust_pointers(); | |
633 } | |
634 | |
635 void PSMarkSweep::mark_sweep_phase4() { | |
636 EventMark m("4 compact heap"); | |
637 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty); | |
638 trace("4"); | |
639 | |
640 // All pointers are now adjusted, move objects accordingly | |
641 | |
642 // It is imperative that we traverse perm_gen first in phase4. All | |
643 // classes must be allocated earlier than their instances, and traversing | |
644 // perm_gen first makes sure that all klassOops have moved to their new | |
645 // location before any instance does a dispatch through it's klass! | |
646 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
647 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
648 | |
649 PSYoungGen* young_gen = heap->young_gen(); | |
650 PSOldGen* old_gen = heap->old_gen(); | |
651 PSPermGen* perm_gen = heap->perm_gen(); | |
652 | |
653 perm_gen->compact(); | |
654 old_gen->compact(); | |
655 young_gen->compact(); | |
656 } | |
657 | |
658 jlong PSMarkSweep::millis_since_last_gc() { | |
659 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc; | |
660 // XXX See note in genCollectedHeap::millis_since_last_gc(). | |
661 if (ret_val < 0) { | |
662 NOT_PRODUCT(warning("time warp: %d", ret_val);) | |
663 return 0; | |
664 } | |
665 return ret_val; | |
666 } | |
667 | |
668 void PSMarkSweep::reset_millis_since_last_gc() { | |
669 _time_of_last_gc = os::javaTimeMillis(); | |
670 } |