1 /*
2 * Copyright (c) 2001, 2018, 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/oopStorageParState.hpp"
33 #include "gc/shared/plab.hpp"
34 #include "gc/shared/preservedMarks.hpp"
35 #include "gc/shared/taskqueue.hpp"
36 #include "memory/padded.hpp"
37
38 class ChunkArray;
39 class CMSHeap;
40 class ParScanWithoutBarrierClosure;
41 class ParScanWithBarrierClosure;
42 class ParRootScanWithoutBarrierClosure;
43 class ParRootScanWithBarrierTwoGensClosure;
44 class ParEvacuateFollowersClosure;
45 class StrongRootsScope;
46
47 // It would be better if these types could be kept local to the .cpp file,
48 // but they must be here to allow ParScanClosure::do_oop_work to be defined
49 // in genOopClosures.inline.hpp.
50
51 typedef Padded<OopTaskQueue> ObjToScanQueue;
52 typedef GenericTaskQueueSet<ObjToScanQueue, mtGC> ObjToScanQueueSet;
53
54 class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
55 private:
56 ParScanWeakRefClosure* _par_cl;
57 protected:
58 template <class T> void do_oop_work(T* p);
59 public:
60 ParKeepAliveClosure(ParScanWeakRefClosure* cl);
61 virtual void do_oop(oop* p);
62 virtual void do_oop(narrowOop* p);
63 };
64
65 // The state needed by thread performing parallel young-gen collection.
66 class ParScanThreadState {
67 friend class ParScanThreadStateSet;
68 private:
69 ObjToScanQueue *_work_queue;
70 Stack<oop, mtGC>* const _overflow_stack;
71 PreservedMarks* const _preserved_marks;
72
73 PLAB _to_space_alloc_buffer;
74
75 ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier
76 ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier
77 ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier
78 // Will be passed to process_roots to set its generation.
79 ParRootScanWithBarrierTwoGensClosure _older_gen_closure;
80 // This closure will always be bound to the old gen; it will be used
81 // in evacuate_followers.
82 ParRootScanWithBarrierTwoGensClosure _old_gen_root_closure; // scan_old_root_with_gc_barrier
83 ParEvacuateFollowersClosure _evacuate_followers;
84 DefNewGeneration::IsAliveClosure _is_alive_closure;
85 ParScanWeakRefClosure _scan_weak_ref_closure;
86 ParKeepAliveClosure _keep_alive_closure;
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 PreservedMarks* preserved_marks_,
136 size_t desired_plab_sz_,
137 ParallelTaskTerminator& term_);
138
139 public:
140 AgeTable* age_table() {return &_ageTable;}
141
142 ObjToScanQueue* work_queue() { return _work_queue; }
143
144 PreservedMarks* preserved_marks() const { return _preserved_marks; }
145
146 PLAB* to_space_alloc_buffer() {
147 return &_to_space_alloc_buffer;
148 }
149
150 ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; }
151 DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; }
152 ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; }
153 ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; }
154 ParScanClosure& older_gen_closure() { return _older_gen_closure; }
155 ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; };
156
157 // Decrease queue size below "max_size".
158 void trim_queues(int max_size);
159
160 // Private overflow stack usage
161 Stack<oop, mtGC>* overflow_stack() { return _overflow_stack; }
162 bool take_from_overflow_stack();
163 void push_on_overflow_stack(oop p);
164
165 // Is new_obj a candidate for scan_partial_array_and_push_remainder method.
166 inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const;
167
168 int* hash_seed() { return &_hash_seed; }
169 int thread_num() { return _thread_num; }
170
171 // Allocate a to-space block of size "sz", or else return NULL.
172 HeapWord* alloc_in_to_space_slow(size_t word_sz);
173
174 inline HeapWord* alloc_in_to_space(size_t word_sz);
175
176 HeapWord* young_old_boundary() { return _young_old_boundary; }
177
178 void set_young_old_boundary(HeapWord *boundary) {
179 _young_old_boundary = boundary;
180 }
181
182 // Undo the most recent allocation ("obj", of "word_sz").
183 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
184
185 // Promotion failure stats
186 void register_promotion_failure(size_t sz) {
187 _promotion_failed_info.register_copy_failure(sz);
188 }
189 PromotionFailedInfo& promotion_failed_info() {
190 return _promotion_failed_info;
191 }
192 bool promotion_failed() {
193 return _promotion_failed_info.has_failed();
194 }
195 void print_promotion_failure_size();
196
197 #if TASKQUEUE_STATS
198 TaskQueueStats & taskqueue_stats() const { return _work_queue->stats; }
199
200 size_t term_attempts() const { return _term_attempts; }
201 size_t overflow_refills() const { return _overflow_refills; }
202 size_t overflow_refill_objs() const { return _overflow_refill_objs; }
203
204 void note_term_attempt() { ++_term_attempts; }
205 void note_overflow_refill(size_t objs) {
206 ++_overflow_refills; _overflow_refill_objs += objs;
207 }
208
209 void reset_stats();
210 #endif // TASKQUEUE_STATS
211
212 void start_strong_roots() {
213 _start_strong_roots = os::elapsedTime();
214 }
215 void end_strong_roots() {
216 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
217 }
218 double strong_roots_time() const { return _strong_roots_time; }
219 void start_term_time() {
220 TASKQUEUE_STATS_ONLY(note_term_attempt());
221 _start_term = os::elapsedTime();
222 }
223 void end_term_time() {
224 _term_time += (os::elapsedTime() - _start_term);
225 }
226 double term_time() const { return _term_time; }
227
228 double elapsed_time() const {
229 return os::elapsedTime() - _start;
230 }
231 };
232
233 class ParNewGenTask: public AbstractGangTask {
234 private:
235 ParNewGeneration* _young_gen;
236 Generation* _old_gen;
237 HeapWord* _young_old_boundary;
238 class ParScanThreadStateSet* _state_set;
239 StrongRootsScope* _strong_roots_scope;
240 OopStorage::ParState<false, false> _par_state_string;
241
242 public:
243 ParNewGenTask(ParNewGeneration* young_gen,
244 Generation* old_gen,
245 HeapWord* young_old_boundary,
246 ParScanThreadStateSet* state_set,
247 StrongRootsScope* strong_roots_scope);
248
249 HeapWord* young_old_boundary() { return _young_old_boundary; }
250
251 void work(uint worker_id);
252 };
253
254 class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
255 protected:
256 template <class T> void do_oop_work(T* p);
257 public:
258 KeepAliveClosure(ScanWeakRefClosure* cl);
259 virtual void do_oop(oop* p);
260 virtual void do_oop(narrowOop* p);
261 };
262
263 template <typename OopClosureType1, typename OopClosureType2>
264 class EvacuateFollowersClosureGeneral: public VoidClosure {
265 private:
266 CMSHeap* _heap;
267 OopClosureType1* _scan_cur_or_nonheap;
268 OopClosureType2* _scan_older;
269 public:
270 EvacuateFollowersClosureGeneral(CMSHeap* heap,
271 OopClosureType1* cur,
272 OopClosureType2* older);
273 virtual void do_void();
274 };
275
276 // Closure for scanning ParNewGeneration.
277 // Same as ScanClosure, except does parallel GC barrier.
278 class ScanClosureWithParBarrier: public ScanClosure {
279 protected:
280 template <class T> void do_oop_work(T* p);
281 public:
282 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
283 virtual void do_oop(oop* p);
284 virtual void do_oop(narrowOop* p);
285 };
286
287 // Implements AbstractRefProcTaskExecutor for ParNew.
288 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
289 private:
290 ParNewGeneration& _young_gen;
291 Generation& _old_gen;
292 ParScanThreadStateSet& _state_set;
293 public:
294 ParNewRefProcTaskExecutor(ParNewGeneration& young_gen,
295 Generation& old_gen,
296 ParScanThreadStateSet& state_set)
297 : _young_gen(young_gen), _old_gen(old_gen), _state_set(state_set)
298 { }
299
300 // Executes a task using worker threads.
301 virtual void execute(ProcessTask& task);
302 // Switch to single threaded mode.
303 virtual void set_single_threaded_mode();
304 };
305
306
307 // A Generation that does parallel young-gen collection.
308
309 class ParNewGeneration: public DefNewGeneration {
310 friend class ParNewGenTask;
311 friend class ParNewRefProcTask;
312 friend class ParNewRefProcTaskExecutor;
313 friend class ParScanThreadStateSet;
314 friend class ParEvacuateFollowersClosure;
315
316 private:
317 // The per-worker-thread work queues
318 ObjToScanQueueSet* _task_queues;
319
320 // Per-worker-thread local overflow stacks
321 Stack<oop, mtGC>* _overflow_stacks;
322
323 // Desired size of survivor space plab's
324 PLABStats _plab_stats;
325
326 // A list of from-space images of to-be-scanned objects, threaded through
327 // klass-pointers (klass information already copied to the forwarded
328 // image.) Manipulated with CAS.
329 oopDesc* volatile _overflow_list;
330 NOT_PRODUCT(ssize_t _num_par_pushes;)
331
332 // This closure is used by the reference processor to filter out
333 // references to live referent.
334 DefNewGeneration::IsAliveClosure _is_alive_closure;
335
336 // GC tracer that should be used during collection.
337 ParNewTracer _gc_tracer;
338
339 static oop real_forwardee_slow(oop obj);
340 static void waste_some_time();
341
342 void handle_promotion_failed(CMSHeap* gch, ParScanThreadStateSet& thread_state_set);
343
344 protected:
345
346 bool _survivor_overflow;
347
348 bool survivor_overflow() { return _survivor_overflow; }
349 void set_survivor_overflow(bool v) { _survivor_overflow = v; }
350
351 void restore_preserved_marks();
352
353 public:
354 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size);
355
356 ~ParNewGeneration() {
357 for (uint i = 0; i < ParallelGCThreads; i++)
358 delete _task_queues->queue(i);
359
360 delete _task_queues;
361 }
362
363 virtual void ref_processor_init();
364 virtual Generation::Name kind() { return Generation::ParNew; }
365 virtual const char* name() const;
366 virtual const char* short_name() const { return "ParNew"; }
367
368 // override
369 virtual bool refs_discovery_is_mt() const {
370 return ParallelGCThreads > 1;
371 }
372
373 // Make the collection virtual.
374 virtual void collect(bool full,
375 bool clear_all_soft_refs,
376 size_t size,
377 bool is_tlab);
378
379 // This needs to be visible to the closure function.
380 // "obj" is the object to be copied, "m" is a recent value of its mark
381 // that must not contain a forwarding pointer (though one might be
382 // inserted in "obj"s mark word by a parallel thread).
383 oop copy_to_survivor_space(ParScanThreadState* par_scan_state,
384 oop obj, size_t obj_sz, markOop m);
385
386 // in support of testing overflow code
387 NOT_PRODUCT(int _overflow_counter;)
388 NOT_PRODUCT(bool should_simulate_overflow();)
389
390 // Accessor for overflow list
391 oop overflow_list() { return _overflow_list; }
392
393 // Push the given (from-space) object on the global overflow list.
394 void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state);
395
396 // If the global overflow list is non-empty, move some tasks from it
397 // onto "work_q" (which need not be empty). No more than 1/4 of the
398 // available space on "work_q" is used.
399 bool take_from_overflow_list(ParScanThreadState* par_scan_state);
400 bool take_from_overflow_list_work(ParScanThreadState* par_scan_state);
401
402 // The task queues to be used by parallel GC threads.
403 ObjToScanQueueSet* task_queues() {
404 return _task_queues;
405 }
406
407 PLABStats* plab_stats() {
408 return &_plab_stats;
409 }
410
411 size_t desired_plab_sz();
412
413 const ParNewTracer* gc_tracer() const {
414 return &_gc_tracer;
415 }
416
417 static oop real_forwardee(oop obj);
418 };
419
420 #endif // SHARE_VM_GC_CMS_PARNEWGENERATION_HPP