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annotate src/share/vm/memory/genMarkSweep.cpp @ 1905:ce6848d0666d
6968367: can_post_on_exceptions is still using VM_DeoptimizeFrame in some places
Reviewed-by: kvn, twisti
author | never |
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date | Tue, 19 Oct 2010 16:14:34 -0700 |
parents | 894b1d7c7e01 |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 #include "incls/_precompiled.incl" | |
26 #include "incls/_genMarkSweep.cpp.incl" | |
27 | |
28 void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp, | |
29 bool clear_all_softrefs) { | |
30 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); | |
31 | |
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32 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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33 #ifdef ASSERT |
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34 if (gch->collector_policy()->should_clear_all_soft_refs()) { |
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35 assert(clear_all_softrefs, "Policy should have been checked earlier"); |
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36 } |
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37 #endif |
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38 |
0 | 39 // hook up weak ref data so it can be used during Mark-Sweep |
40 assert(ref_processor() == NULL, "no stomping"); | |
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41 assert(rp != NULL, "should be non-NULL"); |
0 | 42 _ref_processor = rp; |
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43 rp->setup_policy(clear_all_softrefs); |
0 | 44 |
45 TraceTime t1("Full GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); | |
46 | |
47 // When collecting the permanent generation methodOops may be moving, | |
48 // so we either have to flush all bcp data or convert it into bci. | |
49 CodeCache::gc_prologue(); | |
50 Threads::gc_prologue(); | |
51 | |
52 // Increment the invocation count for the permanent generation, since it is | |
53 // implicitly collected whenever we do a full mark sweep collection. | |
54 gch->perm_gen()->stat_record()->invocations++; | |
55 | |
56 // Capture heap size before collection for printing. | |
57 size_t gch_prev_used = gch->used(); | |
58 | |
59 // Some of the card table updates below assume that the perm gen is | |
60 // also being collected. | |
61 assert(level == gch->n_gens() - 1, | |
62 "All generations are being collected, ergo perm gen too."); | |
63 | |
64 // Capture used regions for each generation that will be | |
65 // subject to collection, so that card table adjustments can | |
66 // be made intelligently (see clear / invalidate further below). | |
67 gch->save_used_regions(level, true /* perm */); | |
68 | |
69 allocate_stacks(); | |
70 | |
71 mark_sweep_phase1(level, clear_all_softrefs); | |
72 | |
73 mark_sweep_phase2(); | |
74 | |
75 // Don't add any more derived pointers during phase3 | |
76 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); | |
77 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); | |
78 | |
79 mark_sweep_phase3(level); | |
80 | |
81 VALIDATE_MARK_SWEEP_ONLY( | |
82 if (ValidateMarkSweep) { | |
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83 guarantee(_root_refs_stack->length() == 0, "should be empty by now"); |
0 | 84 } |
85 ) | |
86 | |
87 mark_sweep_phase4(); | |
88 | |
89 VALIDATE_MARK_SWEEP_ONLY( | |
90 if (ValidateMarkSweep) { | |
91 guarantee(_live_oops->length() == _live_oops_moved_to->length(), | |
92 "should be the same size"); | |
93 } | |
94 ) | |
95 | |
96 restore_marks(); | |
97 | |
98 // Set saved marks for allocation profiler (and other things? -- dld) | |
99 // (Should this be in general part?) | |
100 gch->save_marks(); | |
101 | |
102 deallocate_stacks(); | |
103 | |
104 // If compaction completely evacuated all generations younger than this | |
105 // one, then we can clear the card table. Otherwise, we must invalidate | |
106 // it (consider all cards dirty). In the future, we might consider doing | |
107 // compaction within generations only, and doing card-table sliding. | |
108 bool all_empty = true; | |
109 for (int i = 0; all_empty && i < level; i++) { | |
110 Generation* g = gch->get_gen(i); | |
111 all_empty = all_empty && gch->get_gen(i)->used() == 0; | |
112 } | |
113 GenRemSet* rs = gch->rem_set(); | |
114 // Clear/invalidate below make use of the "prev_used_regions" saved earlier. | |
115 if (all_empty) { | |
116 // We've evacuated all generations below us. | |
117 Generation* g = gch->get_gen(level); | |
118 rs->clear_into_younger(g, true /* perm */); | |
119 } else { | |
120 // Invalidate the cards corresponding to the currently used | |
121 // region and clear those corresponding to the evacuated region | |
122 // of all generations just collected (i.e. level and younger). | |
123 rs->invalidate_or_clear(gch->get_gen(level), | |
124 true /* younger */, | |
125 true /* perm */); | |
126 } | |
127 | |
128 Threads::gc_epilogue(); | |
129 CodeCache::gc_epilogue(); | |
130 | |
131 if (PrintGC && !PrintGCDetails) { | |
132 gch->print_heap_change(gch_prev_used); | |
133 } | |
134 | |
135 // refs processing: clean slate | |
136 _ref_processor = NULL; | |
137 | |
138 // Update heap occupancy information which is used as | |
139 // input to soft ref clearing policy at the next gc. | |
140 Universe::update_heap_info_at_gc(); | |
141 | |
142 // Update time of last gc for all generations we collected | |
143 // (which curently is all the generations in the heap). | |
144 gch->update_time_of_last_gc(os::javaTimeMillis()); | |
145 } | |
146 | |
147 void GenMarkSweep::allocate_stacks() { | |
148 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
149 // Scratch request on behalf of oldest generation; will do no | |
150 // allocation. | |
151 ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0); | |
152 | |
153 // $$$ To cut a corner, we'll only use the first scratch block, and then | |
154 // revert to malloc. | |
155 if (scratch != NULL) { | |
156 _preserved_count_max = | |
157 scratch->num_words * HeapWordSize / sizeof(PreservedMark); | |
158 } else { | |
159 _preserved_count_max = 0; | |
160 } | |
161 | |
162 _preserved_marks = (PreservedMark*)scratch; | |
163 _preserved_count = 0; | |
164 | |
165 #ifdef VALIDATE_MARK_SWEEP | |
166 if (ValidateMarkSweep) { | |
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167 _root_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
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168 _other_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
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169 _adjusted_pointers = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
0 | 170 _live_oops = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); |
171 _live_oops_moved_to = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); | |
172 _live_oops_size = new (ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); | |
173 } | |
174 if (RecordMarkSweepCompaction) { | |
175 if (_cur_gc_live_oops == NULL) { | |
176 _cur_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); | |
177 _cur_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); | |
178 _cur_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); | |
179 _last_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); | |
180 _last_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); | |
181 _last_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); | |
182 } else { | |
183 _cur_gc_live_oops->clear(); | |
184 _cur_gc_live_oops_moved_to->clear(); | |
185 _cur_gc_live_oops_size->clear(); | |
186 } | |
187 } | |
188 #endif | |
189 } | |
190 | |
191 | |
192 void GenMarkSweep::deallocate_stacks() { | |
356 | 193 if (!UseG1GC) { |
194 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
195 gch->release_scratch(); | |
196 } | |
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197 |
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198 _preserved_mark_stack.clear(true); |
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199 _preserved_oop_stack.clear(true); |
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200 _marking_stack.clear(); |
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201 _objarray_stack.clear(true); |
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202 _revisit_klass_stack.clear(true); |
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203 _revisit_mdo_stack.clear(true); |
0 | 204 |
205 #ifdef VALIDATE_MARK_SWEEP | |
206 if (ValidateMarkSweep) { | |
207 delete _root_refs_stack; | |
208 delete _other_refs_stack; | |
209 delete _adjusted_pointers; | |
210 delete _live_oops; | |
211 delete _live_oops_size; | |
212 delete _live_oops_moved_to; | |
213 _live_oops_index = 0; | |
214 _live_oops_index_at_perm = 0; | |
215 } | |
216 #endif | |
217 } | |
218 | |
219 void GenMarkSweep::mark_sweep_phase1(int level, | |
220 bool clear_all_softrefs) { | |
221 // Recursively traverse all live objects and mark them | |
222 EventMark m("1 mark object"); | |
223 TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty); | |
224 trace(" 1"); | |
225 | |
226 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); | |
227 | |
228 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
229 | |
230 // Because follow_root_closure is created statically, cannot | |
231 // use OopsInGenClosure constructor which takes a generation, | |
232 // as the Universe has not been created when the static constructors | |
233 // are run. | |
234 follow_root_closure.set_orig_generation(gch->get_gen(level)); | |
235 | |
236 gch->gen_process_strong_roots(level, | |
237 false, // Younger gens are not roots. | |
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238 true, // activate StrongRootsScope |
0 | 239 true, // Collecting permanent generation. |
240 SharedHeap::SO_SystemClasses, | |
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241 &follow_root_closure, |
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242 true, // walk code active on stacks |
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243 &follow_root_closure); |
0 | 244 |
245 // Process reference objects found during marking | |
246 { | |
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247 ref_processor()->setup_policy(clear_all_softrefs); |
0 | 248 ref_processor()->process_discovered_references( |
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249 &is_alive, &keep_alive, &follow_stack_closure, NULL); |
0 | 250 } |
251 | |
252 // Follow system dictionary roots and unload classes | |
253 bool purged_class = SystemDictionary::do_unloading(&is_alive); | |
254 | |
255 // Follow code cache roots | |
256 CodeCache::do_unloading(&is_alive, &keep_alive, purged_class); | |
257 follow_stack(); // Flush marking stack | |
258 | |
259 // Update subklass/sibling/implementor links of live klasses | |
260 follow_weak_klass_links(); | |
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261 assert(_marking_stack.is_empty(), "just drained"); |
0 | 262 |
941 | 263 // Visit memoized MDO's and clear any unmarked weak refs |
264 follow_mdo_weak_refs(); | |
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265 assert(_marking_stack.is_empty(), "just drained"); |
941 | 266 |
0 | 267 // Visit symbol and interned string tables and delete unmarked oops |
268 SymbolTable::unlink(&is_alive); | |
269 StringTable::unlink(&is_alive); | |
270 | |
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271 assert(_marking_stack.is_empty(), "stack should be empty by now"); |
0 | 272 } |
273 | |
274 | |
275 void GenMarkSweep::mark_sweep_phase2() { | |
276 // Now all live objects are marked, compute the new object addresses. | |
277 | |
278 // It is imperative that we traverse perm_gen LAST. If dead space is | |
279 // allowed a range of dead object may get overwritten by a dead int | |
280 // array. If perm_gen is not traversed last a klassOop may get | |
281 // overwritten. This is fine since it is dead, but if the class has dead | |
282 // instances we have to skip them, and in order to find their size we | |
283 // need the klassOop! | |
284 // | |
285 // It is not required that we traverse spaces in the same order in | |
286 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops | |
287 // tracking expects us to do so. See comment under phase4. | |
288 | |
289 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
290 Generation* pg = gch->perm_gen(); | |
291 | |
292 EventMark m("2 compute new addresses"); | |
293 TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty); | |
294 trace("2"); | |
295 | |
296 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); | |
297 | |
298 gch->prepare_for_compaction(); | |
299 | |
300 VALIDATE_MARK_SWEEP_ONLY(_live_oops_index_at_perm = _live_oops_index); | |
301 CompactPoint perm_cp(pg, NULL, NULL); | |
302 pg->prepare_for_compaction(&perm_cp); | |
303 } | |
304 | |
305 class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure { | |
306 public: | |
307 void do_generation(Generation* gen) { | |
308 gen->adjust_pointers(); | |
309 } | |
310 }; | |
311 | |
312 void GenMarkSweep::mark_sweep_phase3(int level) { | |
313 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
314 Generation* pg = gch->perm_gen(); | |
315 | |
316 // Adjust the pointers to reflect the new locations | |
317 EventMark m("3 adjust pointers"); | |
318 TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty); | |
319 trace("3"); | |
320 | |
321 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); | |
322 | |
323 // Needs to be done before the system dictionary is adjusted. | |
324 pg->pre_adjust_pointers(); | |
325 | |
326 // Because the two closures below are created statically, cannot | |
327 // use OopsInGenClosure constructor which takes a generation, | |
328 // as the Universe has not been created when the static constructors | |
329 // are run. | |
330 adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level)); | |
331 adjust_pointer_closure.set_orig_generation(gch->get_gen(level)); | |
332 | |
333 gch->gen_process_strong_roots(level, | |
334 false, // Younger gens are not roots. | |
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335 true, // activate StrongRootsScope |
0 | 336 true, // Collecting permanent generation. |
337 SharedHeap::SO_AllClasses, | |
338 &adjust_root_pointer_closure, | |
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339 false, // do not walk code |
0 | 340 &adjust_root_pointer_closure); |
341 | |
342 // Now adjust pointers in remaining weak roots. (All of which should | |
343 // have been cleared if they pointed to non-surviving objects.) | |
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344 CodeBlobToOopClosure adjust_code_pointer_closure(&adjust_pointer_closure, |
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345 /*do_marking=*/ false); |
0 | 346 gch->gen_process_weak_roots(&adjust_root_pointer_closure, |
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347 &adjust_code_pointer_closure, |
0 | 348 &adjust_pointer_closure); |
349 | |
350 adjust_marks(); | |
351 GenAdjustPointersClosure blk; | |
352 gch->generation_iterate(&blk, true); | |
353 pg->adjust_pointers(); | |
354 } | |
355 | |
356 class GenCompactClosure: public GenCollectedHeap::GenClosure { | |
357 public: | |
358 void do_generation(Generation* gen) { | |
359 gen->compact(); | |
360 } | |
361 }; | |
362 | |
363 void GenMarkSweep::mark_sweep_phase4() { | |
364 // All pointers are now adjusted, move objects accordingly | |
365 | |
366 // It is imperative that we traverse perm_gen first in phase4. All | |
367 // classes must be allocated earlier than their instances, and traversing | |
368 // perm_gen first makes sure that all klassOops have moved to their new | |
369 // location before any instance does a dispatch through it's klass! | |
370 | |
371 // The ValidateMarkSweep live oops tracking expects us to traverse spaces | |
372 // in the same order in phase2, phase3 and phase4. We don't quite do that | |
373 // here (perm_gen first rather than last), so we tell the validate code | |
374 // to use a higher index (saved from phase2) when verifying perm_gen. | |
375 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
376 Generation* pg = gch->perm_gen(); | |
377 | |
378 EventMark m("4 compact heap"); | |
379 TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty); | |
380 trace("4"); | |
381 | |
382 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(true)); | |
383 | |
384 pg->compact(); | |
385 | |
386 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); | |
387 | |
388 GenCompactClosure blk; | |
389 gch->generation_iterate(&blk, true); | |
390 | |
391 VALIDATE_MARK_SWEEP_ONLY(compaction_complete()); | |
392 | |
393 pg->post_compact(); // Shared spaces verification. | |
394 } |