1 /*
2 * Copyright (c) 2001, 2017, 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.
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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/preservedMarks.hpp"
34 #include "gc/shared/taskqueue.hpp"
35 #include "memory/padded.hpp"
36
37 class ChunkArray;
38 class CMSHeap;
39 class ParScanWithoutBarrierClosure;
40 class ParScanWithBarrierClosure;
41 class ParRootScanWithoutBarrierClosure;
42 class ParRootScanWithBarrierTwoGensClosure;
43 class ParEvacuateFollowersClosure;
44 class StrongRootsScope;
45
46 // It would be better if these types could be kept local to the .cpp file,
47 // but they must be here to allow ParScanClosure::do_oop_work to be defined
48 // in genOopClosures.inline.hpp.
49
50 typedef Padded<OopTaskQueue> ObjToScanQueue;
51 typedef GenericTaskQueueSet<ObjToScanQueue, mtGC> ObjToScanQueueSet;
52
53 class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
54 private:
55 ParScanWeakRefClosure* _par_cl;
56 protected:
57 template <class T> void do_oop_work(T* p);
58 public:
59 ParKeepAliveClosure(ParScanWeakRefClosure* cl);
60 virtual void do_oop(oop* p);
61 virtual void do_oop(narrowOop* p);
62 };
63
64 // The state needed by thread performing parallel young-gen collection.
65 class ParScanThreadState {
66 friend class ParScanThreadStateSet;
67 private:
68 ObjToScanQueue *_work_queue;
69 Stack<oop, mtGC>* const _overflow_stack;
70 PreservedMarks* const _preserved_marks;
71
72 PLAB _to_space_alloc_buffer;
73
74 ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier
75 ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier
76 ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier
77 // Will be passed to process_roots to set its generation.
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 Space* _to_space;
88 Space* to_space() { return _to_space; }
89
90 ParNewGeneration* _young_gen;
91 ParNewGeneration* young_gen() const { return _young_gen; }
92
93 Generation* _old_gen;
94 Generation* old_gen() { return _old_gen; }
95
96 HeapWord *_young_old_boundary;
97
98 int _hash_seed;
99 int _thread_num;
100 AgeTable _ageTable;
101
102 bool _to_space_full;
103
104 #if TASKQUEUE_STATS
105 size_t _term_attempts;
106 size_t _overflow_refills;
107 size_t _overflow_refill_objs;
108 #endif // TASKQUEUE_STATS
109
110 // Stats for promotion failure
111 PromotionFailedInfo _promotion_failed_info;
112
113 // Timing numbers.
114 double _start;
115 double _start_strong_roots;
116 double _strong_roots_time;
117 double _start_term;
118 double _term_time;
119
120 // Helper for trim_queues. Scans subset of an array and makes
121 // remainder available for work stealing.
122 void scan_partial_array_and_push_remainder(oop obj);
123
124 // In support of CMS' parallel rescan of survivor space.
125 ChunkArray* _survivor_chunk_array;
126 ChunkArray* survivor_chunk_array() { return _survivor_chunk_array; }
127
128 void record_survivor_plab(HeapWord* plab_start, size_t plab_word_size);
129
130 ParScanThreadState(Space* to_space_, ParNewGeneration* gen_,
131 Generation* old_gen_, int thread_num_,
132 ObjToScanQueueSet* work_queue_set_,
133 Stack<oop, mtGC>* overflow_stacks_,
134 PreservedMarks* preserved_marks_,
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 PreservedMarks* preserved_marks() const { return _preserved_marks; }
144
145 PLAB* to_space_alloc_buffer() {
146 return &_to_space_alloc_buffer;
147 }
148
149 ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; }
150 DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; }
151 ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; }
152 ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; }
153 ParScanClosure& older_gen_closure() { return _older_gen_closure; }
154 ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; };
155
156 // Decrease queue size below "max_size".
157 void trim_queues(int max_size);
158
159 // Private overflow stack usage
160 Stack<oop, mtGC>* overflow_stack() { return _overflow_stack; }
161 bool take_from_overflow_stack();
162 void push_on_overflow_stack(oop p);
163
164 // Is new_obj a candidate for scan_partial_array_and_push_remainder method.
165 inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const;
166
167 int* hash_seed() { return &_hash_seed; }
168 int thread_num() { return _thread_num; }
169
170 // Allocate a to-space block of size "sz", or else return NULL.
171 HeapWord* alloc_in_to_space_slow(size_t word_sz);
172
173 inline HeapWord* alloc_in_to_space(size_t word_sz);
174
175 HeapWord* young_old_boundary() { return _young_old_boundary; }
176
177 void set_young_old_boundary(HeapWord *boundary) {
178 _young_old_boundary = boundary;
179 }
180
181 // Undo the most recent allocation ("obj", of "word_sz").
182 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
183
184 // Promotion failure stats
185 void register_promotion_failure(size_t sz) {
186 _promotion_failed_info.register_copy_failure(sz);
187 }
188 PromotionFailedInfo& promotion_failed_info() {
189 return _promotion_failed_info;
190 }
191 bool promotion_failed() {
192 return _promotion_failed_info.has_failed();
193 }
194 void print_promotion_failure_size();
195
196 #if TASKQUEUE_STATS
197 TaskQueueStats & taskqueue_stats() const { return _work_queue->stats; }
198
199 size_t term_attempts() const { return _term_attempts; }
200 size_t overflow_refills() const { return _overflow_refills; }
201 size_t overflow_refill_objs() const { return _overflow_refill_objs; }
202
203 void note_term_attempt() { ++_term_attempts; }
204 void note_overflow_refill(size_t objs) {
205 ++_overflow_refills; _overflow_refill_objs += objs;
206 }
207
208 void reset_stats();
209 #endif // TASKQUEUE_STATS
210
211 void start_strong_roots() {
212 _start_strong_roots = os::elapsedTime();
213 }
214 void end_strong_roots() {
215 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
216 }
217 double strong_roots_time() const { return _strong_roots_time; }
218 void start_term_time() {
219 TASKQUEUE_STATS_ONLY(note_term_attempt());
220 _start_term = os::elapsedTime();
221 }
222 void end_term_time() {
223 _term_time += (os::elapsedTime() - _start_term);
224 }
225 double term_time() const { return _term_time; }
226
227 double elapsed_time() const {
228 return os::elapsedTime() - _start;
229 }
230 };
231
232 class ParNewGenTask: public AbstractGangTask {
233 private:
234 ParNewGeneration* _young_gen;
235 Generation* _old_gen;
236 HeapWord* _young_old_boundary;
237 class ParScanThreadStateSet* _state_set;
238 StrongRootsScope* _strong_roots_scope;
239
240 public:
241 ParNewGenTask(ParNewGeneration* young_gen,
242 Generation* old_gen,
243 HeapWord* young_old_boundary,
244 ParScanThreadStateSet* state_set,
245 StrongRootsScope* strong_roots_scope);
246
247 HeapWord* young_old_boundary() { return _young_old_boundary; }
248
249 void work(uint worker_id);
250 };
251
252 class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
253 protected:
254 template <class T> void do_oop_work(T* p);
255 public:
256 KeepAliveClosure(ScanWeakRefClosure* cl);
257 virtual void do_oop(oop* p);
258 virtual void do_oop(narrowOop* p);
259 };
260
261 class EvacuateFollowersClosureGeneral: public VoidClosure {
262 private:
263 CMSHeap* _heap;
264 OopsInGenClosure* _scan_cur_or_nonheap;
265 OopsInGenClosure* _scan_older;
266 public:
267 EvacuateFollowersClosureGeneral(CMSHeap* heap,
268 OopsInGenClosure* cur,
269 OopsInGenClosure* older);
270 virtual void do_void();
271 };
272
273 // Closure for scanning ParNewGeneration.
274 // Same as ScanClosure, except does parallel GC barrier.
275 class ScanClosureWithParBarrier: public ScanClosure {
276 protected:
277 template <class T> void do_oop_work(T* p);
278 public:
279 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
280 virtual void do_oop(oop* p);
281 virtual void do_oop(narrowOop* p);
282 };
283
284 // Implements AbstractRefProcTaskExecutor for ParNew.
285 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
286 private:
287 ParNewGeneration& _young_gen;
288 Generation& _old_gen;
289 ParScanThreadStateSet& _state_set;
290 public:
291 ParNewRefProcTaskExecutor(ParNewGeneration& young_gen,
292 Generation& old_gen,
293 ParScanThreadStateSet& state_set)
294 : _young_gen(young_gen), _old_gen(old_gen), _state_set(state_set)
295 { }
296
297 // Executes a task using worker threads.
298 virtual void execute(ProcessTask& task);
299 virtual void execute(EnqueueTask& task);
300 // Switch to single threaded mode.
301 virtual void set_single_threaded_mode();
302 };
303
304
305 // A Generation that does parallel young-gen collection.
306
307 class ParNewGeneration: public DefNewGeneration {
308 friend class ParNewGenTask;
309 friend class ParNewRefProcTask;
310 friend class ParNewRefProcTaskExecutor;
311 friend class ParScanThreadStateSet;
312 friend class ParEvacuateFollowersClosure;
313
314 private:
315 // The per-worker-thread work queues
316 ObjToScanQueueSet* _task_queues;
317
318 // Per-worker-thread local overflow stacks
319 Stack<oop, mtGC>* _overflow_stacks;
320
321 // Desired size of survivor space plab's
322 PLABStats _plab_stats;
323
324 // A list of from-space images of to-be-scanned objects, threaded through
325 // klass-pointers (klass information already copied to the forwarded
326 // image.) Manipulated with CAS.
327 oopDesc* volatile _overflow_list;
328 NOT_PRODUCT(ssize_t _num_par_pushes;)
329
330 // This closure is used by the reference processor to filter out
331 // references to live referent.
332 DefNewGeneration::IsAliveClosure _is_alive_closure;
333
334 // GC tracer that should be used during collection.
335 ParNewTracer _gc_tracer;
336
337 static oop real_forwardee_slow(oop obj);
338 static void waste_some_time();
339
340 void handle_promotion_failed(CMSHeap* gch, ParScanThreadStateSet& thread_state_set);
341
342 protected:
343
344 bool _survivor_overflow;
345
346 bool survivor_overflow() { return _survivor_overflow; }
347 void set_survivor_overflow(bool v) { _survivor_overflow = v; }
348
349 void restore_preserved_marks();
350
351 public:
352 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, size_t min_byte_size, size_t max_byte_size);
353
354 ~ParNewGeneration() {
355 for (uint i = 0; i < ParallelGCThreads; i++)
356 delete _task_queues->queue(i);
357
358 delete _task_queues;
359 }
360
361 virtual void ref_processor_init();
362 virtual Generation::Name kind() { return Generation::ParNew; }
363 virtual const char* name() const;
364 virtual const char* short_name() const { return "ParNew"; }
365
366 // override
367 virtual bool refs_discovery_is_mt() const {
368 return ParallelGCThreads > 1;
369 }
370
371 // Make the collection virtual.
372 virtual void collect(bool full,
373 bool clear_all_soft_refs,
374 size_t size,
375 bool is_tlab);
376
377 // This needs to be visible to the closure function.
378 // "obj" is the object to be copied, "m" is a recent value of its mark
379 // that must not contain a forwarding pointer (though one might be
380 // inserted in "obj"s mark word by a parallel thread).
381 oop copy_to_survivor_space(ParScanThreadState* par_scan_state,
382 oop obj, size_t obj_sz, markOop m);
383
384 // in support of testing overflow code
385 NOT_PRODUCT(int _overflow_counter;)
386 NOT_PRODUCT(bool should_simulate_overflow();)
387
388 // Accessor for overflow list
389 oop overflow_list() { return _overflow_list; }
390
391 // Push the given (from-space) object on the global overflow list.
392 void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state);
393
394 // If the global overflow list is non-empty, move some tasks from it
395 // onto "work_q" (which need not be empty). No more than 1/4 of the
396 // available space on "work_q" is used.
397 bool take_from_overflow_list(ParScanThreadState* par_scan_state);
398 bool take_from_overflow_list_work(ParScanThreadState* par_scan_state);
399
400 // The task queues to be used by parallel GC threads.
401 ObjToScanQueueSet* task_queues() {
402 return _task_queues;
403 }
404
405 PLABStats* plab_stats() {
406 return &_plab_stats;
407 }
408
409 size_t desired_plab_sz();
410
411 const ParNewTracer* gc_tracer() const {
412 return &_gc_tracer;
413 }
414
415 static oop real_forwardee(oop obj);
416 };
417
418 #endif // SHARE_VM_GC_CMS_PARNEWGENERATION_HPP