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comparison src/share/vm/gc_implementation/parNew/parNewGeneration.hpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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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 class ChunkArray;
26 class ParScanWithoutBarrierClosure;
27 class ParScanWithBarrierClosure;
28 class ParRootScanWithoutBarrierClosure;
29 class ParRootScanWithBarrierTwoGensClosure;
30 class ParEvacuateFollowersClosure;
31
32 // It would be better if these types could be kept local to the .cpp file,
33 // but they must be here to allow ParScanClosure::do_oop_work to be defined
34 // in genOopClosures.inline.hpp.
35
36
37 typedef OopTaskQueue ObjToScanQueue;
38 typedef OopTaskQueueSet ObjToScanQueueSet;
39
40 // Enable this to get push/pop/steal stats.
41 const int PAR_STATS_ENABLED = 0;
42
43 class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
44 ParScanWeakRefClosure* _par_cl;
45 public:
46 ParKeepAliveClosure(ParScanWeakRefClosure* cl);
47 void do_oop(oop* p);
48 };
49
50 // The state needed by thread performing parallel young-gen collection.
51 class ParScanThreadState {
52 friend class ParScanThreadStateSet;
53 ObjToScanQueue *_work_queue;
54
55 ParGCAllocBuffer _to_space_alloc_buffer;
56
57 ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier
58 ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier
59 ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier
60 // One of these two will be passed to process_strong_roots, which will
61 // set its generation. The first is for two-gen configs where the
62 // old gen collects the perm gen; the second is for arbitrary configs.
63 // The second isn't used right now (it used to be used for the train, an
64 // incremental collector) but the declaration has been left as a reminder.
65 ParRootScanWithBarrierTwoGensClosure _older_gen_closure;
66 // This closure will always be bound to the old gen; it will be used
67 // in evacuate_followers.
68 ParRootScanWithBarrierTwoGensClosure _old_gen_root_closure; // scan_old_root_with_gc_barrier
69 ParEvacuateFollowersClosure _evacuate_followers;
70 DefNewGeneration::IsAliveClosure _is_alive_closure;
71 ParScanWeakRefClosure _scan_weak_ref_closure;
72 ParKeepAliveClosure _keep_alive_closure;
73
74
75 Space* _to_space;
76 Space* to_space() { return _to_space; }
77
78 Generation* _old_gen;
79 Generation* old_gen() { return _old_gen; }
80
81 HeapWord *_young_old_boundary;
82
83 int _hash_seed;
84 int _thread_num;
85 ageTable _ageTable;
86
87 bool _to_space_full;
88
89 int _pushes, _pops, _steals, _steal_attempts, _term_attempts;
90 int _overflow_pushes, _overflow_refills, _overflow_refill_objs;
91
92 // Timing numbers.
93 double _start;
94 double _start_strong_roots;
95 double _strong_roots_time;
96 double _start_term;
97 double _term_time;
98
99 // Helper for trim_queues. Scans subset of an array and makes
100 // remainder available for work stealing.
101 void scan_partial_array_and_push_remainder(oop obj);
102
103 // In support of CMS' parallel rescan of survivor space.
104 ChunkArray* _survivor_chunk_array;
105 ChunkArray* survivor_chunk_array() { return _survivor_chunk_array; }
106
107 void record_survivor_plab(HeapWord* plab_start, size_t plab_word_size);
108
109 ParScanThreadState(Space* to_space_, ParNewGeneration* gen_,
110 Generation* old_gen_, int thread_num_,
111 ObjToScanQueueSet* work_queue_set_, size_t desired_plab_sz_,
112 ParallelTaskTerminator& term_);
113
114 public:
115 ageTable* age_table() {return &_ageTable;}
116
117 ObjToScanQueue* work_queue() { return _work_queue; }
118
119 ParGCAllocBuffer* to_space_alloc_buffer() {
120 return &_to_space_alloc_buffer;
121 }
122
123 ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; }
124 DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; }
125 ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; }
126 ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; }
127 ParScanClosure& older_gen_closure() { return _older_gen_closure; }
128 ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; };
129
130 // Decrease queue size below "max_size".
131 void trim_queues(int max_size);
132
133 // Is new_obj a candidate for scan_partial_array_and_push_remainder method.
134 inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const;
135
136 int* hash_seed() { return &_hash_seed; }
137 int thread_num() { return _thread_num; }
138
139 // Allocate a to-space block of size "sz", or else return NULL.
140 HeapWord* alloc_in_to_space_slow(size_t word_sz);
141
142 HeapWord* alloc_in_to_space(size_t word_sz) {
143 HeapWord* obj = to_space_alloc_buffer()->allocate(word_sz);
144 if (obj != NULL) return obj;
145 else return alloc_in_to_space_slow(word_sz);
146 }
147
148 HeapWord* young_old_boundary() { return _young_old_boundary; }
149
150 void set_young_old_boundary(HeapWord *boundary) {
151 _young_old_boundary = boundary;
152 }
153
154 // Undo the most recent allocation ("obj", of "word_sz").
155 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
156
157 int pushes() { return _pushes; }
158 int pops() { return _pops; }
159 int steals() { return _steals; }
160 int steal_attempts() { return _steal_attempts; }
161 int term_attempts() { return _term_attempts; }
162 int overflow_pushes() { return _overflow_pushes; }
163 int overflow_refills() { return _overflow_refills; }
164 int overflow_refill_objs() { return _overflow_refill_objs; }
165
166 void note_push() { if (PAR_STATS_ENABLED) _pushes++; }
167 void note_pop() { if (PAR_STATS_ENABLED) _pops++; }
168 void note_steal() { if (PAR_STATS_ENABLED) _steals++; }
169 void note_steal_attempt() { if (PAR_STATS_ENABLED) _steal_attempts++; }
170 void note_term_attempt() { if (PAR_STATS_ENABLED) _term_attempts++; }
171 void note_overflow_push() { if (PAR_STATS_ENABLED) _overflow_pushes++; }
172 void note_overflow_refill(int objs) {
173 if (PAR_STATS_ENABLED) {
174 _overflow_refills++;
175 _overflow_refill_objs += objs;
176 }
177 }
178
179 void start_strong_roots() {
180 _start_strong_roots = os::elapsedTime();
181 }
182 void end_strong_roots() {
183 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
184 }
185 double strong_roots_time() { return _strong_roots_time; }
186 void start_term_time() {
187 note_term_attempt();
188 _start_term = os::elapsedTime();
189 }
190 void end_term_time() {
191 _term_time += (os::elapsedTime() - _start_term);
192 }
193 double term_time() { return _term_time; }
194
195 double elapsed() {
196 return os::elapsedTime() - _start;
197 }
198
199 };
200
201 class ParNewGenTask: public AbstractGangTask {
202 ParNewGeneration* _gen;
203 Generation* _next_gen;
204 HeapWord* _young_old_boundary;
205 class ParScanThreadStateSet* _state_set;
206
207 public:
208 ParNewGenTask(ParNewGeneration* gen,
209 Generation* next_gen,
210 HeapWord* young_old_boundary,
211 ParScanThreadStateSet* state_set);
212
213 HeapWord* young_old_boundary() { return _young_old_boundary; }
214
215 void work(int i);
216 };
217
218 class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
219 public:
220 KeepAliveClosure(ScanWeakRefClosure* cl);
221 void do_oop(oop* p);
222 };
223
224 class EvacuateFollowersClosureGeneral: public VoidClosure {
225 GenCollectedHeap* _gch;
226 int _level;
227 OopsInGenClosure* _scan_cur_or_nonheap;
228 OopsInGenClosure* _scan_older;
229 public:
230 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level,
231 OopsInGenClosure* cur,
232 OopsInGenClosure* older);
233 void do_void();
234 };
235
236 // Closure for scanning ParNewGeneration.
237 // Same as ScanClosure, except does parallel GC barrier.
238 class ScanClosureWithParBarrier: public ScanClosure {
239 public:
240 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
241 void do_oop(oop* p);
242 };
243
244 // Implements AbstractRefProcTaskExecutor for ParNew.
245 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
246 public:
247
248 ParNewRefProcTaskExecutor(ParNewGeneration& generation,
249 ParScanThreadStateSet& state_set)
250 : _generation(generation), _state_set(state_set)
251 { }
252
253 // Executes a task using worker threads.
254 virtual void execute(ProcessTask& task);
255 virtual void execute(EnqueueTask& task);
256 // Switch to single threaded mode.
257 virtual void set_single_threaded_mode();
258 private:
259 ParNewGeneration& _generation;
260 ParScanThreadStateSet& _state_set;
261 };
262
263
264 // A Generation that does parallel young-gen collection.
265
266 class ParNewGeneration: public DefNewGeneration {
267 friend class ParNewGenTask;
268 friend class ParNewRefProcTask;
269 friend class ParNewRefProcTaskExecutor;
270 friend class ParScanThreadStateSet;
271
272 // XXX use a global constant instead of 64!
273 struct ObjToScanQueuePadded {
274 ObjToScanQueue work_queue;
275 char pad[64 - sizeof(ObjToScanQueue)]; // prevent false sharing
276 };
277
278 // The per-thread work queues, available here for stealing.
279 ObjToScanQueueSet* _task_queues;
280
281 // Desired size of survivor space plab's
282 PLABStats _plab_stats;
283
284 // A list of from-space images of to-be-scanned objects, threaded through
285 // klass-pointers (klass information already copied to the forwarded
286 // image.) Manipulated with CAS.
287 oop _overflow_list;
288
289 // If true, older generation does not support promotion undo, so avoid.
290 static bool _avoid_promotion_undo;
291
292 // This closure is used by the reference processor to filter out
293 // references to live referent.
294 DefNewGeneration::IsAliveClosure _is_alive_closure;
295
296 static oop real_forwardee_slow(oop obj);
297 static void waste_some_time();
298
299 // Preserve the mark of "obj", if necessary, in preparation for its mark
300 // word being overwritten with a self-forwarding-pointer.
301 void preserve_mark_if_necessary(oop obj, markOop m);
302
303 protected:
304
305 bool _survivor_overflow;
306
307 bool avoid_promotion_undo() { return _avoid_promotion_undo; }
308 void set_avoid_promotion_undo(bool v) { _avoid_promotion_undo = v; }
309
310 bool survivor_overflow() { return _survivor_overflow; }
311 void set_survivor_overflow(bool v) { _survivor_overflow = v; }
312
313 // Adjust the tenuring threshold. See the implementation for
314 // the details of the policy.
315 virtual void adjust_desired_tenuring_threshold();
316
317 public:
318 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level);
319
320 ~ParNewGeneration() {
321 for (uint i = 0; i < ParallelGCThreads; i++)
322 delete _task_queues->queue(i);
323
324 delete _task_queues;
325 }
326
327 virtual void ref_processor_init();
328 virtual Generation::Name kind() { return Generation::ParNew; }
329 virtual const char* name() const;
330 virtual const char* short_name() const { return "ParNew"; }
331
332 // override
333 virtual bool refs_discovery_is_mt() const {
334 assert(UseParNewGC, "ParNewGeneration only when UseParNewGC");
335 return ParallelGCThreads > 1;
336 }
337
338 // Make the collection virtual.
339 virtual void collect(bool full,
340 bool clear_all_soft_refs,
341 size_t size,
342 bool is_tlab);
343
344 // This needs to be visible to the closure function.
345 // "obj" is the object to be copied, "m" is a recent value of its mark
346 // that must not contain a forwarding pointer (though one might be
347 // inserted in "obj"s mark word by a parallel thread).
348 inline oop copy_to_survivor_space(ParScanThreadState* par_scan_state,
349 oop obj, size_t obj_sz, markOop m) {
350 if (_avoid_promotion_undo) {
351 return copy_to_survivor_space_avoiding_promotion_undo(par_scan_state,
352 obj, obj_sz, m);
353 }
354
355 return copy_to_survivor_space_with_undo(par_scan_state, obj, obj_sz, m);
356 }
357
358 oop copy_to_survivor_space_avoiding_promotion_undo(ParScanThreadState* par_scan_state,
359 oop obj, size_t obj_sz, markOop m);
360
361 oop copy_to_survivor_space_with_undo(ParScanThreadState* par_scan_state,
362 oop obj, size_t obj_sz, markOop m);
363
364 // Push the given (from-space) object on the global overflow list.
365 void push_on_overflow_list(oop from_space_obj);
366
367 // If the global overflow list is non-empty, move some tasks from it
368 // onto "work_q" (which must be empty). No more than 1/4 of the
369 // max_elems of "work_q" are moved.
370 bool take_from_overflow_list(ParScanThreadState* par_scan_state);
371
372 // The task queues to be used by parallel GC threads.
373 ObjToScanQueueSet* task_queues() {
374 return _task_queues;
375 }
376
377 PLABStats* plab_stats() {
378 return &_plab_stats;
379 }
380
381 size_t desired_plab_sz() {
382 return _plab_stats.desired_plab_sz();
383 }
384
385 static oop real_forwardee(oop obj);
386
387 DEBUG_ONLY(static bool is_legal_forward_ptr(oop p);)
388 };