1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #ifndef SHARE_VM_GC_CMS_PARNEWGENERATION_HPP
26 #define SHARE_VM_GC_CMS_PARNEWGENERATION_HPP
27
28 #include "gc/cms/parOopClosures.hpp"
29 #include "gc/serial/defNewGeneration.hpp"
30 #include "gc/shared/copyFailedInfo.hpp"
31 #include "gc/shared/gcTrace.hpp"
32 #include "gc/shared/plab.hpp"
33 #include "gc/shared/taskqueue.hpp"
34 #include "memory/padded.hpp"
35
36 class ChunkArray;
37 class ParScanWithoutBarrierClosure;
38 class ParScanWithBarrierClosure;
39 class ParRootScanWithoutBarrierClosure;
40 class ParRootScanWithBarrierTwoGensClosure;
41 class ParEvacuateFollowersClosure;
42 class StrongRootsScope;
43
44 // It would be better if these types could be kept local to the .cpp file,
45 // but they must be here to allow ParScanClosure::do_oop_work to be defined
46 // in genOopClosures.inline.hpp.
47
48 typedef Padded<OopTaskQueue> ObjToScanQueue;
49 typedef GenericTaskQueueSet<ObjToScanQueue, mtGC> ObjToScanQueueSet;
50
51 class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
52 private:
53 ParScanWeakRefClosure* _par_cl;
54 protected:
55 template <class T> void do_oop_work(T* p);
56 public:
57 ParKeepAliveClosure(ParScanWeakRefClosure* cl);
58 virtual void do_oop(oop* p);
59 virtual void do_oop(narrowOop* p);
60 };
61
62 // The state needed by thread performing parallel young-gen collection.
63 class ParScanThreadState {
64 friend class ParScanThreadStateSet;
65 private:
66 ObjToScanQueue *_work_queue;
67 Stack<oop, mtGC>* const _overflow_stack;
68
69 PLAB _to_space_alloc_buffer;
70
71 ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier
72 ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier
73 ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier
74 // Will be passed to process_roots to set its generation.
75 ParRootScanWithBarrierTwoGensClosure _older_gen_closure;
76 // This closure will always be bound to the old gen; it will be used
77 // in evacuate_followers.
78 ParRootScanWithBarrierTwoGensClosure _old_gen_root_closure; // scan_old_root_with_gc_barrier
79 ParEvacuateFollowersClosure _evacuate_followers;
80 DefNewGeneration::IsAliveClosure _is_alive_closure;
81 ParScanWeakRefClosure _scan_weak_ref_closure;
82 ParKeepAliveClosure _keep_alive_closure;
83
84 Space* _to_space;
85 Space* to_space() { return _to_space; }
86
87 ParNewGeneration* _young_gen;
88 ParNewGeneration* young_gen() const { return _young_gen; }
89
90 Generation* _old_gen;
91 Generation* old_gen() { return _old_gen; }
92
93 HeapWord *_young_old_boundary;
94
95 int _hash_seed;
96 int _thread_num;
97 AgeTable _ageTable;
98
99 bool _to_space_full;
100
101 #if TASKQUEUE_STATS
102 size_t _term_attempts;
103 size_t _overflow_refills;
104 size_t _overflow_refill_objs;
105 #endif // TASKQUEUE_STATS
106
107 // Stats for promotion failure
108 PromotionFailedInfo _promotion_failed_info;
109
110 // Timing numbers.
111 double _start;
112 double _start_strong_roots;
113 double _strong_roots_time;
114 double _start_term;
115 double _term_time;
116
117 // Helper for trim_queues. Scans subset of an array and makes
118 // remainder available for work stealing.
119 void scan_partial_array_and_push_remainder(oop obj);
120
121 // In support of CMS' parallel rescan of survivor space.
122 ChunkArray* _survivor_chunk_array;
123 ChunkArray* survivor_chunk_array() { return _survivor_chunk_array; }
124
125 void record_survivor_plab(HeapWord* plab_start, size_t plab_word_size);
126
127 ParScanThreadState(Space* to_space_, ParNewGeneration* gen_,
128 Generation* old_gen_, int thread_num_,
129 ObjToScanQueueSet* work_queue_set_,
130 Stack<oop, mtGC>* overflow_stacks_,
131 size_t desired_plab_sz_,
132 ParallelTaskTerminator& term_);
133
134 public:
135 AgeTable* age_table() {return &_ageTable;}
136
137 ObjToScanQueue* work_queue() { return _work_queue; }
138
139 PLAB* to_space_alloc_buffer() {
140 return &_to_space_alloc_buffer;
141 }
142
143 ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; }
144 DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; }
145 ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; }
146 ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; }
147 ParScanClosure& older_gen_closure() { return _older_gen_closure; }
148 ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; };
149
150 // Decrease queue size below "max_size".
151 void trim_queues(int max_size);
152
153 // Private overflow stack usage
154 Stack<oop, mtGC>* overflow_stack() { return _overflow_stack; }
155 bool take_from_overflow_stack();
156 void push_on_overflow_stack(oop p);
157
158 // Is new_obj a candidate for scan_partial_array_and_push_remainder method.
159 inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const;
160
161 int* hash_seed() { return &_hash_seed; }
162 int thread_num() { return _thread_num; }
163
164 // Allocate a to-space block of size "sz", or else return NULL.
165 HeapWord* alloc_in_to_space_slow(size_t word_sz);
166
167 inline HeapWord* alloc_in_to_space(size_t word_sz);
168
169 HeapWord* young_old_boundary() { return _young_old_boundary; }
170
171 void set_young_old_boundary(HeapWord *boundary) {
172 _young_old_boundary = boundary;
173 }
174
175 // Undo the most recent allocation ("obj", of "word_sz").
176 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
177
178 // Promotion failure stats
179 void register_promotion_failure(size_t sz) {
180 _promotion_failed_info.register_copy_failure(sz);
181 }
182 PromotionFailedInfo& promotion_failed_info() {
183 return _promotion_failed_info;
184 }
185 bool promotion_failed() {
186 return _promotion_failed_info.has_failed();
187 }
188 void print_promotion_failure_size();
189
190 #if TASKQUEUE_STATS
191 TaskQueueStats & taskqueue_stats() const { return _work_queue->stats; }
192
193 size_t term_attempts() const { return _term_attempts; }
194 size_t overflow_refills() const { return _overflow_refills; }
195 size_t overflow_refill_objs() const { return _overflow_refill_objs; }
196
197 void note_term_attempt() { ++_term_attempts; }
198 void note_overflow_refill(size_t objs) {
199 ++_overflow_refills; _overflow_refill_objs += objs;
200 }
201
202 void reset_stats();
203 #endif // TASKQUEUE_STATS
204
205 void start_strong_roots() {
206 _start_strong_roots = os::elapsedTime();
207 }
208 void end_strong_roots() {
209 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
210 }
211 double strong_roots_time() const { return _strong_roots_time; }
212 void start_term_time() {
213 TASKQUEUE_STATS_ONLY(note_term_attempt());
214 _start_term = os::elapsedTime();
215 }
216 void end_term_time() {
217 _term_time += (os::elapsedTime() - _start_term);
218 }
219 double term_time() const { return _term_time; }
220
221 double elapsed_time() const {
222 return os::elapsedTime() - _start;
223 }
224 };
225
226 class ParNewGenTask: public AbstractGangTask {
227 private:
228 ParNewGeneration* _young_gen;
229 Generation* _old_gen;
230 HeapWord* _young_old_boundary;
231 class ParScanThreadStateSet* _state_set;
232 StrongRootsScope* _strong_roots_scope;
233
234 public:
235 ParNewGenTask(ParNewGeneration* young_gen,
236 Generation* old_gen,
237 HeapWord* young_old_boundary,
238 ParScanThreadStateSet* state_set,
239 StrongRootsScope* strong_roots_scope);
240
241 HeapWord* young_old_boundary() { return _young_old_boundary; }
242
243 void work(uint worker_id);
244 };
245
246 class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
247 protected:
248 template <class T> void do_oop_work(T* p);
249 public:
250 KeepAliveClosure(ScanWeakRefClosure* cl);
251 virtual void do_oop(oop* p);
252 virtual void do_oop(narrowOop* p);
253 };
254
255 class EvacuateFollowersClosureGeneral: public VoidClosure {
256 private:
257 GenCollectedHeap* _gch;
258 OopsInGenClosure* _scan_cur_or_nonheap;
259 OopsInGenClosure* _scan_older;
260 public:
261 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch,
262 OopsInGenClosure* cur,
263 OopsInGenClosure* older);
264 virtual void do_void();
265 };
266
267 // Closure for scanning ParNewGeneration.
268 // Same as ScanClosure, except does parallel GC barrier.
269 class ScanClosureWithParBarrier: public ScanClosure {
270 protected:
271 template <class T> void do_oop_work(T* p);
272 public:
273 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
274 virtual void do_oop(oop* p);
275 virtual void do_oop(narrowOop* p);
276 };
277
278 // Implements AbstractRefProcTaskExecutor for ParNew.
279 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
280 private:
281 ParNewGeneration& _young_gen;
282 Generation& _old_gen;
283 ParScanThreadStateSet& _state_set;
284 public:
285 ParNewRefProcTaskExecutor(ParNewGeneration& young_gen,
286 Generation& old_gen,
287 ParScanThreadStateSet& state_set)
288 : _young_gen(young_gen), _old_gen(old_gen), _state_set(state_set)
289 { }
290
291 // Executes a task using worker threads.
292 virtual void execute(ProcessTask& task);
293 virtual void execute(EnqueueTask& task);
294 // Switch to single threaded mode.
295 virtual void set_single_threaded_mode();
296 };
297
298
299 // A Generation that does parallel young-gen collection.
300
301 class ParNewGeneration: public DefNewGeneration {
302 friend class ParNewGenTask;
303 friend class ParNewRefProcTask;
304 friend class ParNewRefProcTaskExecutor;
305 friend class ParScanThreadStateSet;
306 friend class ParEvacuateFollowersClosure;
307
308 private:
309 // The per-worker-thread work queues
310 ObjToScanQueueSet* _task_queues;
311
312 // Per-worker-thread local overflow stacks
313 Stack<oop, mtGC>* _overflow_stacks;
314
315 // Desired size of survivor space plab's
316 PLABStats _plab_stats;
317
318 // A list of from-space images of to-be-scanned objects, threaded through
319 // klass-pointers (klass information already copied to the forwarded
320 // image.) Manipulated with CAS.
321 oop _overflow_list;
322 NOT_PRODUCT(ssize_t _num_par_pushes;)
323
324 // This closure is used by the reference processor to filter out
325 // references to live referent.
326 DefNewGeneration::IsAliveClosure _is_alive_closure;
327
328 // GC tracer that should be used during collection.
329 ParNewTracer _gc_tracer;
330
331 static oop real_forwardee_slow(oop obj);
332 static void waste_some_time();
333
334 // Preserve the mark of "obj", if necessary, in preparation for its mark
335 // word being overwritten with a self-forwarding-pointer.
336 void preserve_mark_if_necessary(oop obj, markOop m);
337
338 void handle_promotion_failed(GenCollectedHeap* gch, ParScanThreadStateSet& thread_state_set);
339
340 protected:
341
342 bool _survivor_overflow;
343
344 bool survivor_overflow() { return _survivor_overflow; }
345 void set_survivor_overflow(bool v) { _survivor_overflow = v; }
346
347 public:
348 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size);
349
350 ~ParNewGeneration() {
351 for (uint i = 0; i < ParallelGCThreads; i++)
352 delete _task_queues->queue(i);
353
354 delete _task_queues;
355 }
356
357 virtual void ref_processor_init();
358 virtual Generation::Name kind() { return Generation::ParNew; }
359 virtual const char* name() const;
360 virtual const char* short_name() const { return "ParNew"; }
361
362 // override
363 virtual bool refs_discovery_is_mt() const {
364 return ParallelGCThreads > 1;
365 }
366
367 // Make the collection virtual.
368 virtual void collect(bool full,
369 bool clear_all_soft_refs,
370 size_t size,
371 bool is_tlab);
372
373 // This needs to be visible to the closure function.
374 // "obj" is the object to be copied, "m" is a recent value of its mark
375 // that must not contain a forwarding pointer (though one might be
376 // inserted in "obj"s mark word by a parallel thread).
377 oop copy_to_survivor_space(ParScanThreadState* par_scan_state,
378 oop obj, size_t obj_sz, markOop m);
379
380 // in support of testing overflow code
381 NOT_PRODUCT(int _overflow_counter;)
382 NOT_PRODUCT(bool should_simulate_overflow();)
383
384 // Accessor for overflow list
385 oop overflow_list() { return _overflow_list; }
386
387 // Push the given (from-space) object on the global overflow list.
388 void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state);
389
390 // If the global overflow list is non-empty, move some tasks from it
391 // onto "work_q" (which need not be empty). No more than 1/4 of the
392 // available space on "work_q" is used.
393 bool take_from_overflow_list(ParScanThreadState* par_scan_state);
394 bool take_from_overflow_list_work(ParScanThreadState* par_scan_state);
395
396 // The task queues to be used by parallel GC threads.
397 ObjToScanQueueSet* task_queues() {
398 return _task_queues;
399 }
400
401 PLABStats* plab_stats() {
402 return &_plab_stats;
403 }
404
405 size_t desired_plab_sz();
406
407 const ParNewTracer* gc_tracer() const {
408 return &_gc_tracer;
409 }
410
411 static oop real_forwardee(oop obj);
412 };
413
414 #endif // SHARE_VM_GC_CMS_PARNEWGENERATION_HPP