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
43 // It would be better if these types could be kept local to the .cpp file,
44 // but they must be here to allow ParScanClosure::do_oop_work to be defined
45 // in genOopClosures.inline.hpp.
46
47 typedef Padded<OopTaskQueue> ObjToScanQueue;
48 typedef GenericTaskQueueSet<ObjToScanQueue, mtGC> ObjToScanQueueSet;
49
50 class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
51 private:
52 ParScanWeakRefClosure* _par_cl;
53 protected:
54 template <class T> void do_oop_work(T* p);
55 public:
56 ParKeepAliveClosure(ParScanWeakRefClosure* cl);
57 virtual void do_oop(oop* p);
58 virtual void do_oop(narrowOop* p);
59 };
60
61 // The state needed by thread performing parallel young-gen collection.
62 class ParScanThreadState {
63 friend class ParScanThreadStateSet;
64 private:
65 ObjToScanQueue *_work_queue;
66 Stack<oop, mtGC>* const _overflow_stack;
67
68 PLAB _to_space_alloc_buffer;
69
70 ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier
71 ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier
72 ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier
73 // One of these two will be passed to process_roots, which will
74 // set its generation. The first is for two-gen configs where the
75 // old gen collects the perm gen; the second is for arbitrary configs.
76 // The second isn't used right now (it used to be used for the train, an
77 // incremental collector) but the declaration has been left as a reminder.
78 ParRootScanWithBarrierTwoGensClosure _older_gen_closure;
79 // This closure will always be bound to the old gen; it will be used
80 // in evacuate_followers.
81 ParRootScanWithBarrierTwoGensClosure _old_gen_root_closure; // scan_old_root_with_gc_barrier
82 ParEvacuateFollowersClosure _evacuate_followers;
83 DefNewGeneration::IsAliveClosure _is_alive_closure;
84 ParScanWeakRefClosure _scan_weak_ref_closure;
85 ParKeepAliveClosure _keep_alive_closure;
86
87
88 Space* _to_space;
89 Space* to_space() { return _to_space; }
90
91 ParNewGeneration* _young_gen;
92 ParNewGeneration* young_gen() const { return _young_gen; }
93
94 Generation* _old_gen;
95 Generation* old_gen() { return _old_gen; }
96
97 HeapWord *_young_old_boundary;
98
99 int _hash_seed;
100 int _thread_num;
101 ageTable _ageTable;
102
103 bool _to_space_full;
104
105 #if TASKQUEUE_STATS
106 size_t _term_attempts;
107 size_t _overflow_refills;
108 size_t _overflow_refill_objs;
109 #endif // TASKQUEUE_STATS
110
111 // Stats for promotion failure
112 PromotionFailedInfo _promotion_failed_info;
113
114 // Timing numbers.
115 double _start;
116 double _start_strong_roots;
117 double _strong_roots_time;
118 double _start_term;
119 double _term_time;
120
121 // Helper for trim_queues. Scans subset of an array and makes
122 // remainder available for work stealing.
123 void scan_partial_array_and_push_remainder(oop obj);
124
125 // In support of CMS' parallel rescan of survivor space.
126 ChunkArray* _survivor_chunk_array;
127 ChunkArray* survivor_chunk_array() { return _survivor_chunk_array; }
128
129 void record_survivor_plab(HeapWord* plab_start, size_t plab_word_size);
130
131 ParScanThreadState(Space* to_space_, ParNewGeneration* gen_,
132 Generation* old_gen_, int thread_num_,
133 ObjToScanQueueSet* work_queue_set_,
134 Stack<oop, mtGC>* overflow_stacks_,
135 size_t desired_plab_sz_,
136 ParallelTaskTerminator& term_);
137
138 public:
139 ageTable* age_table() {return &_ageTable;}
140
141 ObjToScanQueue* work_queue() { return _work_queue; }
142
143 PLAB* to_space_alloc_buffer() {
144 return &_to_space_alloc_buffer;
145 }
146
147 ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; }
148 DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; }
149 ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; }
150 ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; }
151 ParScanClosure& older_gen_closure() { return _older_gen_closure; }
152 ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; };
153
154 // Decrease queue size below "max_size".
155 void trim_queues(int max_size);
156
157 // Private overflow stack usage
158 Stack<oop, mtGC>* overflow_stack() { return _overflow_stack; }
159 bool take_from_overflow_stack();
160 void push_on_overflow_stack(oop p);
161
162 // Is new_obj a candidate for scan_partial_array_and_push_remainder method.
163 inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const;
164
165 int* hash_seed() { return &_hash_seed; }
166 int thread_num() { return _thread_num; }
167
168 // Allocate a to-space block of size "sz", or else return NULL.
169 HeapWord* alloc_in_to_space_slow(size_t word_sz);
170
171 HeapWord* alloc_in_to_space(size_t word_sz) {
172 HeapWord* obj = to_space_alloc_buffer()->allocate_aligned(word_sz, SurvivorAlignmentInBytes);
173 if (obj != NULL) return obj;
174 else return alloc_in_to_space_slow(word_sz);
175 }
176
177 HeapWord* young_old_boundary() { return _young_old_boundary; }
178
179 void set_young_old_boundary(HeapWord *boundary) {
180 _young_old_boundary = boundary;
181 }
182
183 // Undo the most recent allocation ("obj", of "word_sz").
184 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
185
186 // Promotion failure stats
187 void register_promotion_failure(size_t sz) {
188 _promotion_failed_info.register_copy_failure(sz);
189 }
190 PromotionFailedInfo& promotion_failed_info() {
191 return _promotion_failed_info;
192 }
193 bool promotion_failed() {
194 return _promotion_failed_info.has_failed();
195 }
196 void print_promotion_failure_size();
197
198 #if TASKQUEUE_STATS
199 TaskQueueStats & taskqueue_stats() const { return _work_queue->stats; }
200
201 size_t term_attempts() const { return _term_attempts; }
202 size_t overflow_refills() const { return _overflow_refills; }
203 size_t overflow_refill_objs() const { return _overflow_refill_objs; }
204
205 void note_term_attempt() { ++_term_attempts; }
206 void note_overflow_refill(size_t objs) {
207 ++_overflow_refills; _overflow_refill_objs += objs;
208 }
209
210 void reset_stats();
211 #endif // TASKQUEUE_STATS
212
213 void start_strong_roots() {
214 _start_strong_roots = os::elapsedTime();
215 }
216 void end_strong_roots() {
217 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
218 }
219 double strong_roots_time() const { return _strong_roots_time; }
220 void start_term_time() {
221 TASKQUEUE_STATS_ONLY(note_term_attempt());
222 _start_term = os::elapsedTime();
223 }
224 void end_term_time() {
225 _term_time += (os::elapsedTime() - _start_term);
226 }
227 double term_time() const { return _term_time; }
228
229 double elapsed_time() const {
230 return os::elapsedTime() - _start;
231 }
232 };
233
234 class ParNewGenTask: public AbstractGangTask {
235 private:
236 ParNewGeneration* _gen;
237 Generation* _old_gen;
238 HeapWord* _young_old_boundary;
239 class ParScanThreadStateSet* _state_set;
240
241 public:
242 ParNewGenTask(ParNewGeneration* gen,
243 Generation* old_gen,
244 HeapWord* young_old_boundary,
245 ParScanThreadStateSet* state_set);
246
247 HeapWord* young_old_boundary() { return _young_old_boundary; }
248
249 void work(uint worker_id);
250
251 // Reset the terminator in ParScanThreadStateSet for
252 // "active_workers" threads.
253 virtual void set_for_termination(uint active_workers);
254 };
255
256 class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
257 protected:
258 template <class T> void do_oop_work(T* p);
259 public:
260 KeepAliveClosure(ScanWeakRefClosure* cl);
261 virtual void do_oop(oop* p);
262 virtual void do_oop(narrowOop* p);
263 };
264
265 class EvacuateFollowersClosureGeneral: public VoidClosure {
266 private:
267 GenCollectedHeap* _gch;
268 int _level;
269 OopsInGenClosure* _scan_cur_or_nonheap;
270 OopsInGenClosure* _scan_older;
271 public:
272 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level,
273 OopsInGenClosure* cur,
274 OopsInGenClosure* older);
275 virtual void do_void();
276 };
277
278 // Closure for scanning ParNewGeneration.
279 // Same as ScanClosure, except does parallel GC barrier.
280 class ScanClosureWithParBarrier: public ScanClosure {
281 protected:
282 template <class T> void do_oop_work(T* p);
283 public:
284 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
285 virtual void do_oop(oop* p);
286 virtual void do_oop(narrowOop* p);
287 };
288
289 // Implements AbstractRefProcTaskExecutor for ParNew.
290 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
291 private:
292 ParNewGeneration& _generation;
293 ParScanThreadStateSet& _state_set;
294 public:
295 ParNewRefProcTaskExecutor(ParNewGeneration& generation,
296 ParScanThreadStateSet& state_set)
297 : _generation(generation), _state_set(state_set)
298 { }
299
300 // Executes a task using worker threads.
301 virtual void execute(ProcessTask& task);
302 virtual void execute(EnqueueTask& task);
303 // Switch to single threaded mode.
304 virtual void set_single_threaded_mode();
305 };
306
307
308 // A Generation that does parallel young-gen collection.
309
310 class ParNewGeneration: public DefNewGeneration {
311 friend class ParNewGenTask;
312 friend class ParNewRefProcTask;
313 friend class ParNewRefProcTaskExecutor;
314 friend class ParScanThreadStateSet;
315 friend class ParEvacuateFollowersClosure;
316
317 private:
318 // The per-worker-thread work queues
319 ObjToScanQueueSet* _task_queues;
320
321 // Per-worker-thread local overflow stacks
322 Stack<oop, mtGC>* _overflow_stacks;
323
324 // Desired size of survivor space plab's
325 PLABStats _plab_stats;
326
327 // A list of from-space images of to-be-scanned objects, threaded through
328 // klass-pointers (klass information already copied to the forwarded
329 // image.) Manipulated with CAS.
330 oop _overflow_list;
331 NOT_PRODUCT(ssize_t _num_par_pushes;)
332
333 // This closure is used by the reference processor to filter out
334 // references to live referent.
335 DefNewGeneration::IsAliveClosure _is_alive_closure;
336
337 // GC tracer that should be used during collection.
338 ParNewTracer _gc_tracer;
339
340 static oop real_forwardee_slow(oop obj);
341 static void waste_some_time();
342
343 // Preserve the mark of "obj", if necessary, in preparation for its mark
344 // word being overwritten with a self-forwarding-pointer.
345 void preserve_mark_if_necessary(oop obj, markOop m);
346
347 void handle_promotion_failed(GenCollectedHeap* gch, ParScanThreadStateSet& thread_state_set);
348
349 protected:
350
351 bool _survivor_overflow;
352
353 bool survivor_overflow() { return _survivor_overflow; }
354 void set_survivor_overflow(bool v) { _survivor_overflow = v; }
355
356 public:
357 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level);
358
359 ~ParNewGeneration() {
360 for (uint i = 0; i < ParallelGCThreads; i++)
361 delete _task_queues->queue(i);
362
363 delete _task_queues;
364 }
365
366 virtual void ref_processor_init();
367 virtual Generation::Name kind() { return Generation::ParNew; }
368 virtual const char* name() const;
369 virtual const char* short_name() const { return "ParNew"; }
370
371 // override
372 virtual bool refs_discovery_is_mt() const {
373 return ParallelGCThreads > 1;
374 }
375
376 // Make the collection virtual.
377 virtual void collect(bool full,
378 bool clear_all_soft_refs,
379 size_t size,
380 bool is_tlab);
381
382 // This needs to be visible to the closure function.
383 // "obj" is the object to be copied, "m" is a recent value of its mark
384 // that must not contain a forwarding pointer (though one might be
385 // inserted in "obj"s mark word by a parallel thread).
386 oop copy_to_survivor_space(ParScanThreadState* par_scan_state,
387 oop obj, size_t obj_sz, markOop m);
388
389 // in support of testing overflow code
390 NOT_PRODUCT(int _overflow_counter;)
391 NOT_PRODUCT(bool should_simulate_overflow();)
392
393 // Accessor for overflow list
394 oop overflow_list() { return _overflow_list; }
395
396 // Push the given (from-space) object on the global overflow list.
397 void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state);
398
399 // If the global overflow list is non-empty, move some tasks from it
400 // onto "work_q" (which need not be empty). No more than 1/4 of the
401 // available space on "work_q" is used.
402 bool take_from_overflow_list(ParScanThreadState* par_scan_state);
403 bool take_from_overflow_list_work(ParScanThreadState* par_scan_state);
404
405 // The task queues to be used by parallel GC threads.
406 ObjToScanQueueSet* task_queues() {
407 return _task_queues;
408 }
409
410 PLABStats* plab_stats() {
411 return &_plab_stats;
412 }
413
414 size_t desired_plab_sz() {
415 return _plab_stats.desired_plab_sz();
416 }
417
418 const ParNewTracer* gc_tracer() const {
419 return &_gc_tracer;
420 }
421
422 static oop real_forwardee(oop obj);
423 };
424
425 #endif // SHARE_VM_GC_CMS_PARNEWGENERATION_HPP