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 _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 thread_num() { return _thread_num; }
168
169 // Allocate a to-space block of size "sz", or else return NULL.
170 HeapWord* alloc_in_to_space_slow(size_t word_sz);
171
172 inline HeapWord* alloc_in_to_space(size_t word_sz);
173
174 HeapWord* young_old_boundary() { return _young_old_boundary; }
175
176 void set_young_old_boundary(HeapWord *boundary) {
177 _young_old_boundary = boundary;
178 }
179
180 // Undo the most recent allocation ("obj", of "word_sz").
181 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
182
183 // Promotion failure stats
184 void register_promotion_failure(size_t sz) {
185 _promotion_failed_info.register_copy_failure(sz);
186 }
187 PromotionFailedInfo& promotion_failed_info() {
188 return _promotion_failed_info;
189 }
190 bool promotion_failed() {
191 return _promotion_failed_info.has_failed();
192 }
193 void print_promotion_failure_size();
194
195 #if TASKQUEUE_STATS
196 TaskQueueStats & taskqueue_stats() const { return _work_queue->stats; }
197
198 size_t term_attempts() const { return _term_attempts; }
199 size_t overflow_refills() const { return _overflow_refills; }
200 size_t overflow_refill_objs() const { return _overflow_refill_objs; }
201
202 void note_term_attempt() { ++_term_attempts; }
203 void note_overflow_refill(size_t objs) {
204 ++_overflow_refills; _overflow_refill_objs += objs;
205 }
206
207 void reset_stats();
208 #endif // TASKQUEUE_STATS
209
210 void start_strong_roots() {
211 _start_strong_roots = os::elapsedTime();
212 }
213 void end_strong_roots() {
214 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
215 }
216 double strong_roots_time() const { return _strong_roots_time; }
217 void start_term_time() {
218 TASKQUEUE_STATS_ONLY(note_term_attempt());
219 _start_term = os::elapsedTime();
220 }
221 void end_term_time() {
222 _term_time += (os::elapsedTime() - _start_term);
223 }
224 double term_time() const { return _term_time; }
225
226 double elapsed_time() const {
227 return os::elapsedTime() - _start;
228 }
229 };
230
231 class ParNewGenTask: public AbstractGangTask {
232 private:
233 ParNewGeneration* _young_gen;
234 Generation* _old_gen;
235 HeapWord* _young_old_boundary;
236 class ParScanThreadStateSet* _state_set;
237 StrongRootsScope* _strong_roots_scope;
238 OopStorage::ParState<false, false> _par_state_string;
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 template <typename OopClosureType1, typename OopClosureType2>
262 class EvacuateFollowersClosureGeneral: public VoidClosure {
263 private:
264 CMSHeap* _heap;
265 OopClosureType1* _scan_cur_or_nonheap;
266 OopClosureType2* _scan_older;
267 public:
268 EvacuateFollowersClosureGeneral(CMSHeap* heap,
269 OopClosureType1* cur,
270 OopClosureType2* older);
271 virtual void do_void();
272 };
273
274 // Closure for scanning ParNewGeneration.
275 // Same as ScanClosure, except does parallel GC barrier.
276 class ScanClosureWithParBarrier: public OopsInClassLoaderDataOrGenClosure {
277 private:
278 ParNewGeneration* _g;
279 HeapWord* _boundary;
280 bool _gc_barrier;
281
282 template <class T> void do_oop_work(T* p);
283
284 public:
285 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
286 virtual void do_oop(oop* p);
287 virtual void do_oop(narrowOop* p);
288 };
289
290 // Implements AbstractRefProcTaskExecutor for ParNew.
291 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
292 private:
293 ParNewGeneration& _young_gen;
294 Generation& _old_gen;
295 ParScanThreadStateSet& _state_set;
296 public:
297 ParNewRefProcTaskExecutor(ParNewGeneration& young_gen,
298 Generation& old_gen,
299 ParScanThreadStateSet& state_set)
300 : _young_gen(young_gen), _old_gen(old_gen), _state_set(state_set)
301 { }
302
303 // Executes a task using worker threads.
304 virtual void execute(ProcessTask& task, uint ergo_workers);
305 // Switch to single threaded mode.
306 virtual void set_single_threaded_mode();
307 };
308
309
310 // A Generation that does parallel young-gen collection.
311
312 class ParNewGeneration: public DefNewGeneration {
313 friend class ParNewGenTask;
314 friend class ParNewRefProcTask;
315 friend class ParNewRefProcTaskExecutor;
316 friend class ParScanThreadStateSet;
317 friend class ParEvacuateFollowersClosure;
318
319 private:
320 // The per-worker-thread work queues
321 ObjToScanQueueSet* _task_queues;
322
323 // Per-worker-thread local overflow stacks
324 Stack<oop, mtGC>* _overflow_stacks;
325
326 // Desired size of survivor space plab's
327 PLABStats _plab_stats;
328
329 // A list of from-space images of to-be-scanned objects, threaded through
330 // klass-pointers (klass information already copied to the forwarded
331 // image.) Manipulated with CAS.
332 oopDesc* volatile _overflow_list;
333 NOT_PRODUCT(ssize_t _num_par_pushes;)
334
335 // This closure is used by the reference processor to filter out
336 // references to live referent.
337 DefNewGeneration::IsAliveClosure _is_alive_closure;
338
339 // GC tracer that should be used during collection.
340 ParNewTracer _gc_tracer;
341
342 static oop real_forwardee_slow(oop obj);
343 static void waste_some_time();
344
345 void handle_promotion_failed(CMSHeap* gch, ParScanThreadStateSet& thread_state_set);
346
347 protected:
348
349 void restore_preserved_marks();
350
351 public:
352 ParNewGeneration(ReservedSpace rs, size_t initial_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