Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp @ 542:9a25e0c45327
6792421: assert(_bitMap->isMarked(addr+size-1),inconsistent Printezis mark)
Summary: The CMS concurrent precleaning and concurrent marking phases should work around classes that are undergoing redefinition.
Reviewed-by: ysr, tonyp
author | jmasa |
---|---|
date | Sat, 31 Jan 2009 00:15:00 -0800 |
parents | 7d7a7c599c17 |
children | 05c6d52fa7a9 |
rev | line source |
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0 | 1 /* |
337 | 2 * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved. |
0 | 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 | |
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38 _counters = new CollectorCounters("PSMarkSweep", 1); |
0 | 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 | |
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99 // Save information needed to minimize mangling |
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100 heap->record_gen_tops_before_GC(); |
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101 |
0 | 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(); | |
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175 ref_processor()->setup_policy(clear_all_softrefs); |
0 | 176 |
177 mark_sweep_phase1(clear_all_softrefs); | |
178 | |
179 mark_sweep_phase2(); | |
180 | |
181 // Don't add any more derived pointers during phase3 | |
182 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); | |
183 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); | |
184 | |
185 mark_sweep_phase3(); | |
186 | |
187 mark_sweep_phase4(); | |
188 | |
189 restore_marks(); | |
190 | |
191 deallocate_stacks(); | |
192 | |
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193 if (ZapUnusedHeapArea) { |
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194 // Do a complete mangle (top to end) because the usage for |
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195 // scratch does not maintain a top pointer. |
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196 young_gen->to_space()->mangle_unused_area_complete(); |
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197 } |
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198 |
0 | 199 eden_empty = young_gen->eden_space()->is_empty(); |
200 if (!eden_empty) { | |
201 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); | |
202 } | |
203 | |
204 // Update heap occupancy information which is used as | |
205 // input to soft ref clearing policy at the next gc. | |
206 Universe::update_heap_info_at_gc(); | |
207 | |
208 survivors_empty = young_gen->from_space()->is_empty() && | |
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209 young_gen->to_space()->is_empty(); |
0 | 210 young_gen_empty = eden_empty && survivors_empty; |
211 | |
212 BarrierSet* bs = heap->barrier_set(); | |
213 if (bs->is_a(BarrierSet::ModRef)) { | |
214 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs; | |
215 MemRegion old_mr = heap->old_gen()->reserved(); | |
216 MemRegion perm_mr = heap->perm_gen()->reserved(); | |
217 assert(perm_mr.end() <= old_mr.start(), "Generations out of order"); | |
218 | |
219 if (young_gen_empty) { | |
220 modBS->clear(MemRegion(perm_mr.start(), old_mr.end())); | |
221 } else { | |
222 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end())); | |
223 } | |
224 } | |
225 | |
226 BiasedLocking::restore_marks(); | |
227 Threads::gc_epilogue(); | |
228 CodeCache::gc_epilogue(); | |
229 | |
230 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); | |
231 | |
232 ref_processor()->enqueue_discovered_references(NULL); | |
233 | |
234 // Update time of last GC | |
235 reset_millis_since_last_gc(); | |
236 | |
237 // Let the size policy know we're done | |
238 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); | |
239 | |
240 if (UseAdaptiveSizePolicy) { | |
241 | |
242 if (PrintAdaptiveSizePolicy) { | |
243 gclog_or_tty->print("AdaptiveSizeStart: "); | |
244 gclog_or_tty->stamp(); | |
245 gclog_or_tty->print_cr(" collection: %d ", | |
246 heap->total_collections()); | |
247 if (Verbose) { | |
248 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" | |
249 " perm_gen_capacity: %d ", | |
250 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), | |
251 perm_gen->capacity_in_bytes()); | |
252 } | |
253 } | |
254 | |
255 // Don't check if the size_policy is ready here. Let | |
256 // the size_policy check that internally. | |
257 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && | |
258 ((gc_cause != GCCause::_java_lang_system_gc) || | |
259 UseAdaptiveSizePolicyWithSystemGC)) { | |
260 // Calculate optimal free space amounts | |
261 assert(young_gen->max_size() > | |
262 young_gen->from_space()->capacity_in_bytes() + | |
263 young_gen->to_space()->capacity_in_bytes(), | |
264 "Sizes of space in young gen are out-of-bounds"); | |
265 size_t max_eden_size = young_gen->max_size() - | |
266 young_gen->from_space()->capacity_in_bytes() - | |
267 young_gen->to_space()->capacity_in_bytes(); | |
268 size_policy->compute_generation_free_space(young_gen->used_in_bytes(), | |
269 young_gen->eden_space()->used_in_bytes(), | |
270 old_gen->used_in_bytes(), | |
271 perm_gen->used_in_bytes(), | |
272 young_gen->eden_space()->capacity_in_bytes(), | |
273 old_gen->max_gen_size(), | |
274 max_eden_size, | |
275 true /* full gc*/, | |
276 gc_cause); | |
277 | |
278 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); | |
279 | |
280 // Don't resize the young generation at an major collection. A | |
281 // desired young generation size may have been calculated but | |
282 // resizing the young generation complicates the code because the | |
283 // resizing of the old generation may have moved the boundary | |
284 // between the young generation and the old generation. Let the | |
285 // young generation resizing happen at the minor collections. | |
286 } | |
287 if (PrintAdaptiveSizePolicy) { | |
288 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", | |
289 heap->total_collections()); | |
290 } | |
291 } | |
292 | |
293 if (UsePerfData) { | |
294 heap->gc_policy_counters()->update_counters(); | |
295 heap->gc_policy_counters()->update_old_capacity( | |
296 old_gen->capacity_in_bytes()); | |
297 heap->gc_policy_counters()->update_young_capacity( | |
298 young_gen->capacity_in_bytes()); | |
299 } | |
300 | |
301 heap->resize_all_tlabs(); | |
302 | |
303 // We collected the perm gen, so we'll resize it here. | |
304 perm_gen->compute_new_size(perm_gen_prev_used); | |
305 | |
306 if (TraceGen1Time) accumulated_time()->stop(); | |
307 | |
308 if (PrintGC) { | |
309 if (PrintGCDetails) { | |
310 // Don't print a GC timestamp here. This is after the GC so | |
311 // would be confusing. | |
312 young_gen->print_used_change(young_gen_prev_used); | |
313 old_gen->print_used_change(old_gen_prev_used); | |
314 } | |
315 heap->print_heap_change(prev_used); | |
316 // Do perm gen after heap becase prev_used does | |
317 // not include the perm gen (done this way in the other | |
318 // collectors). | |
319 if (PrintGCDetails) { | |
320 perm_gen->print_used_change(perm_gen_prev_used); | |
321 } | |
322 } | |
323 | |
324 // Track memory usage and detect low memory | |
325 MemoryService::track_memory_usage(); | |
326 heap->update_counters(); | |
327 | |
328 if (PrintGCDetails) { | |
329 if (size_policy->print_gc_time_limit_would_be_exceeded()) { | |
330 if (size_policy->gc_time_limit_exceeded()) { | |
331 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit " | |
332 "of %d%%", GCTimeLimit); | |
333 } else { | |
334 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit " | |
335 "of %d%%", GCTimeLimit); | |
336 } | |
337 } | |
338 size_policy->set_print_gc_time_limit_would_be_exceeded(false); | |
339 } | |
340 } | |
341 | |
342 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { | |
343 HandleMark hm; // Discard invalid handles created during verification | |
344 gclog_or_tty->print(" VerifyAfterGC:"); | |
345 Universe::verify(false); | |
346 } | |
347 | |
348 // Re-verify object start arrays | |
349 if (VerifyObjectStartArray && | |
350 VerifyAfterGC) { | |
351 old_gen->verify_object_start_array(); | |
352 perm_gen->verify_object_start_array(); | |
353 } | |
354 | |
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355 if (ZapUnusedHeapArea) { |
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356 old_gen->object_space()->check_mangled_unused_area_complete(); |
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357 perm_gen->object_space()->check_mangled_unused_area_complete(); |
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358 } |
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359 |
0 | 360 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); |
361 | |
362 if (PrintHeapAtGC) { | |
363 Universe::print_heap_after_gc(); | |
364 } | |
365 } | |
366 | |
367 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, | |
368 PSYoungGen* young_gen, | |
369 PSOldGen* old_gen) { | |
370 MutableSpace* const eden_space = young_gen->eden_space(); | |
371 assert(!eden_space->is_empty(), "eden must be non-empty"); | |
372 assert(young_gen->virtual_space()->alignment() == | |
373 old_gen->virtual_space()->alignment(), "alignments do not match"); | |
374 | |
375 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { | |
376 return false; | |
377 } | |
378 | |
379 // Both generations must be completely committed. | |
380 if (young_gen->virtual_space()->uncommitted_size() != 0) { | |
381 return false; | |
382 } | |
383 if (old_gen->virtual_space()->uncommitted_size() != 0) { | |
384 return false; | |
385 } | |
386 | |
387 // Figure out how much to take from eden. Include the average amount promoted | |
388 // in the total; otherwise the next young gen GC will simply bail out to a | |
389 // full GC. | |
390 const size_t alignment = old_gen->virtual_space()->alignment(); | |
391 const size_t eden_used = eden_space->used_in_bytes(); | |
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392 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); |
0 | 393 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); |
394 const size_t eden_capacity = eden_space->capacity_in_bytes(); | |
395 | |
396 if (absorb_size >= eden_capacity) { | |
397 return false; // Must leave some space in eden. | |
398 } | |
399 | |
400 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; | |
401 if (new_young_size < young_gen->min_gen_size()) { | |
402 return false; // Respect young gen minimum size. | |
403 } | |
404 | |
405 if (TraceAdaptiveGCBoundary && Verbose) { | |
406 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: " | |
407 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " | |
408 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " | |
409 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", | |
410 absorb_size / K, | |
411 eden_capacity / K, (eden_capacity - absorb_size) / K, | |
412 young_gen->from_space()->used_in_bytes() / K, | |
413 young_gen->to_space()->used_in_bytes() / K, | |
414 young_gen->capacity_in_bytes() / K, new_young_size / K); | |
415 } | |
416 | |
417 // Fill the unused part of the old gen. | |
418 MutableSpace* const old_space = old_gen->object_space(); | |
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419 HeapWord* const unused_start = old_space->top(); |
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420 size_t const unused_words = pointer_delta(old_space->end(), unused_start); |
0 | 421 |
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422 if (unused_words > 0) { |
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423 if (unused_words < CollectedHeap::min_fill_size()) { |
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424 return false; // If the old gen cannot be filled, must give up. |
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425 } |
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426 CollectedHeap::fill_with_objects(unused_start, unused_words); |
0 | 427 } |
428 | |
429 // Take the live data from eden and set both top and end in the old gen to | |
430 // eden top. (Need to set end because reset_after_change() mangles the region | |
431 // from end to virtual_space->high() in debug builds). | |
432 HeapWord* const new_top = eden_space->top(); | |
433 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), | |
434 absorb_size); | |
435 young_gen->reset_after_change(); | |
436 old_space->set_top(new_top); | |
437 old_space->set_end(new_top); | |
438 old_gen->reset_after_change(); | |
439 | |
440 // Update the object start array for the filler object and the data from eden. | |
441 ObjectStartArray* const start_array = old_gen->start_array(); | |
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442 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { |
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443 start_array->allocate_block(p); |
0 | 444 } |
445 | |
446 // Could update the promoted average here, but it is not typically updated at | |
447 // full GCs and the value to use is unclear. Something like | |
448 // | |
449 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. | |
450 | |
451 size_policy->set_bytes_absorbed_from_eden(absorb_size); | |
452 return true; | |
453 } | |
454 | |
455 void PSMarkSweep::allocate_stacks() { | |
456 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
457 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
458 | |
459 PSYoungGen* young_gen = heap->young_gen(); | |
460 | |
461 MutableSpace* to_space = young_gen->to_space(); | |
462 _preserved_marks = (PreservedMark*)to_space->top(); | |
463 _preserved_count = 0; | |
464 | |
465 // We want to calculate the size in bytes first. | |
466 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); | |
467 // Now divide by the size of a PreservedMark | |
468 _preserved_count_max /= sizeof(PreservedMark); | |
469 | |
470 _preserved_mark_stack = NULL; | |
471 _preserved_oop_stack = NULL; | |
472 | |
473 _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true); | |
474 | |
475 int size = SystemDictionary::number_of_classes() * 2; | |
476 _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true); | |
477 } | |
478 | |
479 | |
480 void PSMarkSweep::deallocate_stacks() { | |
481 if (_preserved_oop_stack) { | |
482 delete _preserved_mark_stack; | |
483 _preserved_mark_stack = NULL; | |
484 delete _preserved_oop_stack; | |
485 _preserved_oop_stack = NULL; | |
486 } | |
487 | |
488 delete _marking_stack; | |
489 delete _revisit_klass_stack; | |
490 } | |
491 | |
492 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { | |
493 // Recursively traverse all live objects and mark them | |
494 EventMark m("1 mark object"); | |
495 TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty); | |
496 trace(" 1"); | |
497 | |
498 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
499 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
500 | |
501 // General strong roots. | |
502 Universe::oops_do(mark_and_push_closure()); | |
503 ReferenceProcessor::oops_do(mark_and_push_closure()); | |
504 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles | |
505 Threads::oops_do(mark_and_push_closure()); | |
506 ObjectSynchronizer::oops_do(mark_and_push_closure()); | |
507 FlatProfiler::oops_do(mark_and_push_closure()); | |
508 Management::oops_do(mark_and_push_closure()); | |
509 JvmtiExport::oops_do(mark_and_push_closure()); | |
510 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); | |
511 vmSymbols::oops_do(mark_and_push_closure()); | |
512 | |
513 // Flush marking stack. | |
514 follow_stack(); | |
515 | |
516 // Process reference objects found during marking | |
517 { | |
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518 ref_processor()->setup_policy(clear_all_softrefs); |
0 | 519 ref_processor()->process_discovered_references( |
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520 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL); |
0 | 521 } |
522 | |
523 // Follow system dictionary roots and unload classes | |
524 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); | |
525 | |
526 // Follow code cache roots | |
527 CodeCache::do_unloading(is_alive_closure(), mark_and_push_closure(), | |
528 purged_class); | |
529 follow_stack(); // Flush marking stack | |
530 | |
531 // Update subklass/sibling/implementor links of live klasses | |
532 follow_weak_klass_links(); | |
533 assert(_marking_stack->is_empty(), "just drained"); | |
534 | |
535 // Visit symbol and interned string tables and delete unmarked oops | |
536 SymbolTable::unlink(is_alive_closure()); | |
537 StringTable::unlink(is_alive_closure()); | |
538 | |
539 assert(_marking_stack->is_empty(), "stack should be empty by now"); | |
540 } | |
541 | |
542 | |
543 void PSMarkSweep::mark_sweep_phase2() { | |
544 EventMark m("2 compute new addresses"); | |
545 TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty); | |
546 trace("2"); | |
547 | |
548 // Now all live objects are marked, compute the new object addresses. | |
549 | |
550 // It is imperative that we traverse perm_gen LAST. If dead space is | |
551 // allowed a range of dead object may get overwritten by a dead int | |
552 // array. If perm_gen is not traversed last a klassOop may get | |
553 // overwritten. This is fine since it is dead, but if the class has dead | |
554 // instances we have to skip them, and in order to find their size we | |
555 // need the klassOop! | |
556 // | |
557 // It is not required that we traverse spaces in the same order in | |
558 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops | |
559 // tracking expects us to do so. See comment under phase4. | |
560 | |
561 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
562 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
563 | |
564 PSOldGen* old_gen = heap->old_gen(); | |
565 PSPermGen* perm_gen = heap->perm_gen(); | |
566 | |
567 // Begin compacting into the old gen | |
568 PSMarkSweepDecorator::set_destination_decorator_tenured(); | |
569 | |
570 // This will also compact the young gen spaces. | |
571 old_gen->precompact(); | |
572 | |
573 // Compact the perm gen into the perm gen | |
574 PSMarkSweepDecorator::set_destination_decorator_perm_gen(); | |
575 | |
576 perm_gen->precompact(); | |
577 } | |
578 | |
579 // This should be moved to the shared markSweep code! | |
580 class PSAlwaysTrueClosure: public BoolObjectClosure { | |
581 public: | |
582 void do_object(oop p) { ShouldNotReachHere(); } | |
583 bool do_object_b(oop p) { return true; } | |
584 }; | |
585 static PSAlwaysTrueClosure always_true; | |
586 | |
587 void PSMarkSweep::mark_sweep_phase3() { | |
588 // Adjust the pointers to reflect the new locations | |
589 EventMark m("3 adjust pointers"); | |
590 TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty); | |
591 trace("3"); | |
592 | |
593 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
594 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
595 | |
596 PSYoungGen* young_gen = heap->young_gen(); | |
597 PSOldGen* old_gen = heap->old_gen(); | |
598 PSPermGen* perm_gen = heap->perm_gen(); | |
599 | |
600 // General strong roots. | |
601 Universe::oops_do(adjust_root_pointer_closure()); | |
602 ReferenceProcessor::oops_do(adjust_root_pointer_closure()); | |
603 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles | |
604 Threads::oops_do(adjust_root_pointer_closure()); | |
605 ObjectSynchronizer::oops_do(adjust_root_pointer_closure()); | |
606 FlatProfiler::oops_do(adjust_root_pointer_closure()); | |
607 Management::oops_do(adjust_root_pointer_closure()); | |
608 JvmtiExport::oops_do(adjust_root_pointer_closure()); | |
609 // SO_AllClasses | |
610 SystemDictionary::oops_do(adjust_root_pointer_closure()); | |
611 vmSymbols::oops_do(adjust_root_pointer_closure()); | |
612 | |
613 // Now adjust pointers in remaining weak roots. (All of which should | |
614 // have been cleared if they pointed to non-surviving objects.) | |
615 // Global (weak) JNI handles | |
616 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure()); | |
617 | |
618 CodeCache::oops_do(adjust_pointer_closure()); | |
619 SymbolTable::oops_do(adjust_root_pointer_closure()); | |
620 StringTable::oops_do(adjust_root_pointer_closure()); | |
621 ref_processor()->weak_oops_do(adjust_root_pointer_closure()); | |
622 PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure()); | |
623 | |
624 adjust_marks(); | |
625 | |
626 young_gen->adjust_pointers(); | |
627 old_gen->adjust_pointers(); | |
628 perm_gen->adjust_pointers(); | |
629 } | |
630 | |
631 void PSMarkSweep::mark_sweep_phase4() { | |
632 EventMark m("4 compact heap"); | |
633 TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty); | |
634 trace("4"); | |
635 | |
636 // All pointers are now adjusted, move objects accordingly | |
637 | |
638 // It is imperative that we traverse perm_gen first in phase4. All | |
639 // classes must be allocated earlier than their instances, and traversing | |
640 // perm_gen first makes sure that all klassOops have moved to their new | |
641 // location before any instance does a dispatch through it's klass! | |
642 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
643 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
644 | |
645 PSYoungGen* young_gen = heap->young_gen(); | |
646 PSOldGen* old_gen = heap->old_gen(); | |
647 PSPermGen* perm_gen = heap->perm_gen(); | |
648 | |
649 perm_gen->compact(); | |
650 old_gen->compact(); | |
651 young_gen->compact(); | |
652 } | |
653 | |
654 jlong PSMarkSweep::millis_since_last_gc() { | |
655 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc; | |
656 // XXX See note in genCollectedHeap::millis_since_last_gc(). | |
657 if (ret_val < 0) { | |
658 NOT_PRODUCT(warning("time warp: %d", ret_val);) | |
659 return 0; | |
660 } | |
661 return ret_val; | |
662 } | |
663 | |
664 void PSMarkSweep::reset_millis_since_last_gc() { | |
665 _time_of_last_gc = os::javaTimeMillis(); | |
666 } |