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annotate src/share/vm/memory/genMarkSweep.cpp @ 3109:3664989976e2
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author | Gilles Duboscq <gilles.duboscq@oracle.com> |
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date | Fri, 01 Jul 2011 12:57:10 +0200 |
parents | 1d1603768966 |
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rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2001, 2011, 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 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "classfile/javaClasses.hpp" | |
27 #include "classfile/symbolTable.hpp" | |
28 #include "classfile/systemDictionary.hpp" | |
29 #include "classfile/vmSymbols.hpp" | |
30 #include "code/codeCache.hpp" | |
31 #include "code/icBuffer.hpp" | |
32 #include "gc_interface/collectedHeap.inline.hpp" | |
33 #include "memory/genCollectedHeap.hpp" | |
34 #include "memory/genMarkSweep.hpp" | |
35 #include "memory/genOopClosures.inline.hpp" | |
36 #include "memory/generation.inline.hpp" | |
37 #include "memory/modRefBarrierSet.hpp" | |
38 #include "memory/referencePolicy.hpp" | |
39 #include "memory/space.hpp" | |
40 #include "oops/instanceRefKlass.hpp" | |
41 #include "oops/oop.inline.hpp" | |
42 #include "prims/jvmtiExport.hpp" | |
43 #include "runtime/fprofiler.hpp" | |
44 #include "runtime/handles.inline.hpp" | |
45 #include "runtime/synchronizer.hpp" | |
46 #include "runtime/vmThread.hpp" | |
47 #include "utilities/copy.hpp" | |
48 #include "utilities/events.hpp" | |
49 #ifdef TARGET_OS_FAMILY_linux | |
50 # include "thread_linux.inline.hpp" | |
51 #endif | |
52 #ifdef TARGET_OS_FAMILY_solaris | |
53 # include "thread_solaris.inline.hpp" | |
54 #endif | |
55 #ifdef TARGET_OS_FAMILY_windows | |
56 # include "thread_windows.inline.hpp" | |
57 #endif | |
0 | 58 |
59 void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp, | |
60 bool clear_all_softrefs) { | |
61 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); | |
62 | |
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63 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
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64 #ifdef ASSERT |
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65 if (gch->collector_policy()->should_clear_all_soft_refs()) { |
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66 assert(clear_all_softrefs, "Policy should have been checked earlier"); |
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67 } |
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68 #endif |
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69 |
0 | 70 // hook up weak ref data so it can be used during Mark-Sweep |
71 assert(ref_processor() == NULL, "no stomping"); | |
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72 assert(rp != NULL, "should be non-NULL"); |
0 | 73 _ref_processor = rp; |
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74 rp->setup_policy(clear_all_softrefs); |
0 | 75 |
76 TraceTime t1("Full GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); | |
77 | |
78 // When collecting the permanent generation methodOops may be moving, | |
79 // so we either have to flush all bcp data or convert it into bci. | |
80 CodeCache::gc_prologue(); | |
81 Threads::gc_prologue(); | |
82 | |
83 // Increment the invocation count for the permanent generation, since it is | |
84 // implicitly collected whenever we do a full mark sweep collection. | |
85 gch->perm_gen()->stat_record()->invocations++; | |
86 | |
87 // Capture heap size before collection for printing. | |
88 size_t gch_prev_used = gch->used(); | |
89 | |
90 // Some of the card table updates below assume that the perm gen is | |
91 // also being collected. | |
92 assert(level == gch->n_gens() - 1, | |
93 "All generations are being collected, ergo perm gen too."); | |
94 | |
95 // Capture used regions for each generation that will be | |
96 // subject to collection, so that card table adjustments can | |
97 // be made intelligently (see clear / invalidate further below). | |
98 gch->save_used_regions(level, true /* perm */); | |
99 | |
100 allocate_stacks(); | |
101 | |
102 mark_sweep_phase1(level, clear_all_softrefs); | |
103 | |
104 mark_sweep_phase2(); | |
105 | |
106 // Don't add any more derived pointers during phase3 | |
107 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); | |
108 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); | |
109 | |
110 mark_sweep_phase3(level); | |
111 | |
112 VALIDATE_MARK_SWEEP_ONLY( | |
113 if (ValidateMarkSweep) { | |
113
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114 guarantee(_root_refs_stack->length() == 0, "should be empty by now"); |
0 | 115 } |
116 ) | |
117 | |
118 mark_sweep_phase4(); | |
119 | |
120 VALIDATE_MARK_SWEEP_ONLY( | |
121 if (ValidateMarkSweep) { | |
122 guarantee(_live_oops->length() == _live_oops_moved_to->length(), | |
123 "should be the same size"); | |
124 } | |
125 ) | |
126 | |
127 restore_marks(); | |
128 | |
129 // Set saved marks for allocation profiler (and other things? -- dld) | |
130 // (Should this be in general part?) | |
131 gch->save_marks(); | |
132 | |
133 deallocate_stacks(); | |
134 | |
135 // If compaction completely evacuated all generations younger than this | |
136 // one, then we can clear the card table. Otherwise, we must invalidate | |
137 // it (consider all cards dirty). In the future, we might consider doing | |
138 // compaction within generations only, and doing card-table sliding. | |
139 bool all_empty = true; | |
140 for (int i = 0; all_empty && i < level; i++) { | |
141 Generation* g = gch->get_gen(i); | |
142 all_empty = all_empty && gch->get_gen(i)->used() == 0; | |
143 } | |
144 GenRemSet* rs = gch->rem_set(); | |
145 // Clear/invalidate below make use of the "prev_used_regions" saved earlier. | |
146 if (all_empty) { | |
147 // We've evacuated all generations below us. | |
148 Generation* g = gch->get_gen(level); | |
149 rs->clear_into_younger(g, true /* perm */); | |
150 } else { | |
151 // Invalidate the cards corresponding to the currently used | |
152 // region and clear those corresponding to the evacuated region | |
153 // of all generations just collected (i.e. level and younger). | |
154 rs->invalidate_or_clear(gch->get_gen(level), | |
155 true /* younger */, | |
156 true /* perm */); | |
157 } | |
158 | |
159 Threads::gc_epilogue(); | |
160 CodeCache::gc_epilogue(); | |
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161 JvmtiExport::gc_epilogue(); |
0 | 162 |
163 if (PrintGC && !PrintGCDetails) { | |
164 gch->print_heap_change(gch_prev_used); | |
165 } | |
166 | |
167 // refs processing: clean slate | |
168 _ref_processor = NULL; | |
169 | |
170 // Update heap occupancy information which is used as | |
171 // input to soft ref clearing policy at the next gc. | |
172 Universe::update_heap_info_at_gc(); | |
173 | |
174 // Update time of last gc for all generations we collected | |
175 // (which curently is all the generations in the heap). | |
176 gch->update_time_of_last_gc(os::javaTimeMillis()); | |
177 } | |
178 | |
179 void GenMarkSweep::allocate_stacks() { | |
180 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
181 // Scratch request on behalf of oldest generation; will do no | |
182 // allocation. | |
183 ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0); | |
184 | |
185 // $$$ To cut a corner, we'll only use the first scratch block, and then | |
186 // revert to malloc. | |
187 if (scratch != NULL) { | |
188 _preserved_count_max = | |
189 scratch->num_words * HeapWordSize / sizeof(PreservedMark); | |
190 } else { | |
191 _preserved_count_max = 0; | |
192 } | |
193 | |
194 _preserved_marks = (PreservedMark*)scratch; | |
195 _preserved_count = 0; | |
196 | |
197 #ifdef VALIDATE_MARK_SWEEP | |
198 if (ValidateMarkSweep) { | |
113
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199 _root_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
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200 _other_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
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201 _adjusted_pointers = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
0 | 202 _live_oops = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); |
203 _live_oops_moved_to = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); | |
204 _live_oops_size = new (ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); | |
205 } | |
206 if (RecordMarkSweepCompaction) { | |
207 if (_cur_gc_live_oops == NULL) { | |
208 _cur_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); | |
209 _cur_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); | |
210 _cur_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); | |
211 _last_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); | |
212 _last_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); | |
213 _last_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); | |
214 } else { | |
215 _cur_gc_live_oops->clear(); | |
216 _cur_gc_live_oops_moved_to->clear(); | |
217 _cur_gc_live_oops_size->clear(); | |
218 } | |
219 } | |
220 #endif | |
221 } | |
222 | |
223 | |
224 void GenMarkSweep::deallocate_stacks() { | |
356 | 225 if (!UseG1GC) { |
226 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
227 gch->release_scratch(); | |
228 } | |
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229 |
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230 _preserved_mark_stack.clear(true); |
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231 _preserved_oop_stack.clear(true); |
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232 _marking_stack.clear(); |
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233 _objarray_stack.clear(true); |
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234 _revisit_klass_stack.clear(true); |
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235 _revisit_mdo_stack.clear(true); |
0 | 236 |
237 #ifdef VALIDATE_MARK_SWEEP | |
238 if (ValidateMarkSweep) { | |
239 delete _root_refs_stack; | |
240 delete _other_refs_stack; | |
241 delete _adjusted_pointers; | |
242 delete _live_oops; | |
243 delete _live_oops_size; | |
244 delete _live_oops_moved_to; | |
245 _live_oops_index = 0; | |
246 _live_oops_index_at_perm = 0; | |
247 } | |
248 #endif | |
249 } | |
250 | |
251 void GenMarkSweep::mark_sweep_phase1(int level, | |
252 bool clear_all_softrefs) { | |
253 // Recursively traverse all live objects and mark them | |
254 EventMark m("1 mark object"); | |
255 TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty); | |
256 trace(" 1"); | |
257 | |
258 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); | |
259 | |
260 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
261 | |
262 // Because follow_root_closure is created statically, cannot | |
263 // use OopsInGenClosure constructor which takes a generation, | |
264 // as the Universe has not been created when the static constructors | |
265 // are run. | |
266 follow_root_closure.set_orig_generation(gch->get_gen(level)); | |
267 | |
268 gch->gen_process_strong_roots(level, | |
269 false, // Younger gens are not roots. | |
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270 true, // activate StrongRootsScope |
0 | 271 true, // Collecting permanent generation. |
272 SharedHeap::SO_SystemClasses, | |
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273 &follow_root_closure, |
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274 true, // walk code active on stacks |
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275 &follow_root_closure); |
0 | 276 |
277 // Process reference objects found during marking | |
278 { | |
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279 ref_processor()->setup_policy(clear_all_softrefs); |
0 | 280 ref_processor()->process_discovered_references( |
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281 &is_alive, &keep_alive, &follow_stack_closure, NULL); |
0 | 282 } |
283 | |
284 // Follow system dictionary roots and unload classes | |
285 bool purged_class = SystemDictionary::do_unloading(&is_alive); | |
286 | |
287 // Follow code cache roots | |
288 CodeCache::do_unloading(&is_alive, &keep_alive, purged_class); | |
289 follow_stack(); // Flush marking stack | |
290 | |
291 // Update subklass/sibling/implementor links of live klasses | |
292 follow_weak_klass_links(); | |
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293 assert(_marking_stack.is_empty(), "just drained"); |
0 | 294 |
941 | 295 // Visit memoized MDO's and clear any unmarked weak refs |
296 follow_mdo_weak_refs(); | |
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297 assert(_marking_stack.is_empty(), "just drained"); |
941 | 298 |
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299 // Visit interned string tables and delete unmarked oops |
0 | 300 StringTable::unlink(&is_alive); |
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301 // Clean up unreferenced symbols in symbol table. |
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302 SymbolTable::unlink(); |
0 | 303 |
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304 assert(_marking_stack.is_empty(), "stack should be empty by now"); |
0 | 305 } |
306 | |
307 | |
308 void GenMarkSweep::mark_sweep_phase2() { | |
309 // Now all live objects are marked, compute the new object addresses. | |
310 | |
311 // It is imperative that we traverse perm_gen LAST. If dead space is | |
312 // allowed a range of dead object may get overwritten by a dead int | |
313 // array. If perm_gen is not traversed last a klassOop may get | |
314 // overwritten. This is fine since it is dead, but if the class has dead | |
315 // instances we have to skip them, and in order to find their size we | |
316 // need the klassOop! | |
317 // | |
318 // It is not required that we traverse spaces in the same order in | |
319 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops | |
320 // tracking expects us to do so. See comment under phase4. | |
321 | |
322 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
323 Generation* pg = gch->perm_gen(); | |
324 | |
325 EventMark m("2 compute new addresses"); | |
326 TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty); | |
327 trace("2"); | |
328 | |
329 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); | |
330 | |
331 gch->prepare_for_compaction(); | |
332 | |
333 VALIDATE_MARK_SWEEP_ONLY(_live_oops_index_at_perm = _live_oops_index); | |
334 CompactPoint perm_cp(pg, NULL, NULL); | |
335 pg->prepare_for_compaction(&perm_cp); | |
336 } | |
337 | |
338 class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure { | |
339 public: | |
340 void do_generation(Generation* gen) { | |
341 gen->adjust_pointers(); | |
342 } | |
343 }; | |
344 | |
345 void GenMarkSweep::mark_sweep_phase3(int level) { | |
346 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
347 Generation* pg = gch->perm_gen(); | |
348 | |
349 // Adjust the pointers to reflect the new locations | |
350 EventMark m("3 adjust pointers"); | |
351 TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty); | |
352 trace("3"); | |
353 | |
354 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); | |
355 | |
356 // Needs to be done before the system dictionary is adjusted. | |
357 pg->pre_adjust_pointers(); | |
358 | |
359 // Because the two closures below are created statically, cannot | |
360 // use OopsInGenClosure constructor which takes a generation, | |
361 // as the Universe has not been created when the static constructors | |
362 // are run. | |
363 adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level)); | |
364 adjust_pointer_closure.set_orig_generation(gch->get_gen(level)); | |
365 | |
366 gch->gen_process_strong_roots(level, | |
367 false, // Younger gens are not roots. | |
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368 true, // activate StrongRootsScope |
0 | 369 true, // Collecting permanent generation. |
370 SharedHeap::SO_AllClasses, | |
371 &adjust_root_pointer_closure, | |
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372 false, // do not walk code |
0 | 373 &adjust_root_pointer_closure); |
374 | |
375 // Now adjust pointers in remaining weak roots. (All of which should | |
376 // have been cleared if they pointed to non-surviving objects.) | |
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377 CodeBlobToOopClosure adjust_code_pointer_closure(&adjust_pointer_closure, |
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378 /*do_marking=*/ false); |
0 | 379 gch->gen_process_weak_roots(&adjust_root_pointer_closure, |
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380 &adjust_code_pointer_closure, |
0 | 381 &adjust_pointer_closure); |
382 | |
383 adjust_marks(); | |
384 GenAdjustPointersClosure blk; | |
385 gch->generation_iterate(&blk, true); | |
386 pg->adjust_pointers(); | |
387 } | |
388 | |
389 class GenCompactClosure: public GenCollectedHeap::GenClosure { | |
390 public: | |
391 void do_generation(Generation* gen) { | |
392 gen->compact(); | |
393 } | |
394 }; | |
395 | |
396 void GenMarkSweep::mark_sweep_phase4() { | |
397 // All pointers are now adjusted, move objects accordingly | |
398 | |
399 // It is imperative that we traverse perm_gen first in phase4. All | |
400 // classes must be allocated earlier than their instances, and traversing | |
401 // perm_gen first makes sure that all klassOops have moved to their new | |
402 // location before any instance does a dispatch through it's klass! | |
403 | |
404 // The ValidateMarkSweep live oops tracking expects us to traverse spaces | |
405 // in the same order in phase2, phase3 and phase4. We don't quite do that | |
406 // here (perm_gen first rather than last), so we tell the validate code | |
407 // to use a higher index (saved from phase2) when verifying perm_gen. | |
408 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
409 Generation* pg = gch->perm_gen(); | |
410 | |
411 EventMark m("4 compact heap"); | |
412 TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty); | |
413 trace("4"); | |
414 | |
415 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(true)); | |
416 | |
417 pg->compact(); | |
418 | |
419 VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); | |
420 | |
421 GenCompactClosure blk; | |
422 gch->generation_iterate(&blk, true); | |
423 | |
424 VALIDATE_MARK_SWEEP_ONLY(compaction_complete()); | |
425 | |
426 pg->post_compact(); // Shared spaces verification. | |
427 } |