1 /*
2 * Copyright (c) 2001, 2013, 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_IMPLEMENTATION_PARNEW_PARNEWGENERATION_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARNEWGENERATION_HPP
27
28 #include "gc_implementation/shared/gcTrace.hpp"
29 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
30 #include "gc_implementation/shared/copyFailedInfo.hpp"
31 #include "memory/defNewGeneration.hpp"
32 #include "memory/padded.hpp"
33 #include "utilities/taskqueue.hpp"
34
35 class ChunkArray;
36 class ParScanWithoutBarrierClosure;
37 class ParScanWithBarrierClosure;
38 class ParRootScanWithoutBarrierClosure;
39 class ParRootScanWithBarrierTwoGensClosure;
40 class ParEvacuateFollowersClosure;
41
42 // It would be better if these types could be kept local to the .cpp file,
43 // but they must be here to allow ParScanClosure::do_oop_work to be defined
44 // in genOopClosures.inline.hpp.
45
46 typedef Padded<OopTaskQueue> ObjToScanQueue;
47 typedef GenericTaskQueueSet<ObjToScanQueue, mtGC> ObjToScanQueueSet;
48
49 class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
50 private:
51 ParScanWeakRefClosure* _par_cl;
52 protected:
53 template <class T> void do_oop_work(T* p);
54 public:
55 ParKeepAliveClosure(ParScanWeakRefClosure* cl);
56 virtual void do_oop(oop* p);
57 virtual void do_oop(narrowOop* p);
58 };
59
60 // The state needed by thread performing parallel young-gen collection.
61 class ParScanThreadState {
62 friend class ParScanThreadStateSet;
63 private:
64 ObjToScanQueue *_work_queue;
65 Stack<oop, mtGC>* const _overflow_stack;
66
67 ParGCAllocBuffer _to_space_alloc_buffer;
68
69 ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier
70 ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier
71 ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier
72 // One of these two will be passed to process_roots, which will
73 // set its generation. The first is for two-gen configs where the
74 // old gen collects the perm gen; the second is for arbitrary configs.
75 // The second isn't used right now (it used to be used for the train, an
76 // incremental collector) but the declaration has been left as a reminder.
77 ParRootScanWithBarrierTwoGensClosure _older_gen_closure;
78 // This closure will always be bound to the old gen; it will be used
79 // in evacuate_followers.
80 ParRootScanWithBarrierTwoGensClosure _old_gen_root_closure; // scan_old_root_with_gc_barrier
81 ParEvacuateFollowersClosure _evacuate_followers;
82 DefNewGeneration::IsAliveClosure _is_alive_closure;
83 ParScanWeakRefClosure _scan_weak_ref_closure;
84 ParKeepAliveClosure _keep_alive_closure;
85
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 ParNewTracer* _gc_tracer;
99
100 int _hash_seed;
101 int _thread_num;
102 ageTable _ageTable;
103
104 bool _to_space_full;
105
106 #if TASKQUEUE_STATS
107 size_t _term_attempts;
108 size_t _overflow_refills;
109 size_t _overflow_refill_objs;
110 #endif // TASKQUEUE_STATS
111
112 // Stats for promotion failure
113 PromotionFailedInfo _promotion_failed_info;
114
115 // Timing numbers.
116 double _start;
117 double _start_strong_roots;
118 double _strong_roots_time;
119 double _start_term;
120 double _term_time;
121
122 // Helper for trim_queues. Scans subset of an array and makes
123 // remainder available for work stealing.
124 void scan_partial_array_and_push_remainder(oop obj);
125
126 // In support of CMS' parallel rescan of survivor space.
127 ChunkArray* _survivor_chunk_array;
128 ChunkArray* survivor_chunk_array() { return _survivor_chunk_array; }
129
130 void record_survivor_plab(HeapWord* plab_start, size_t plab_word_size);
131
132 ParScanThreadState(Space* to_space_, ParNewGeneration* gen_,
133 Generation* old_gen_, int thread_num_,
134 ObjToScanQueueSet* work_queue_set_,
135 Stack<oop, mtGC>* overflow_stacks_,
136 size_t desired_plab_sz_,
137 ParNewTracer* gc_tracer,
138 ParallelTaskTerminator& term_);
139
140 public:
141 ageTable* age_table() {return &_ageTable;}
142
143 ObjToScanQueue* work_queue() { return _work_queue; }
144
145 ParGCAllocBuffer* 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 ParNewTracer* const gc_tracer() { return _gc_tracer; }
168
169 int* hash_seed() { return &_hash_seed; }
170 int thread_num() { return _thread_num; }
171
172 // Allocate a to-space block of size "sz", or else return NULL.
173 // The oop (old) is used to extract information for promotion trace event
174 HeapWord* alloc_in_to_space_slow(size_t word_sz, const oop old, const uint age);
175
176 HeapWord* alloc_in_to_space(size_t word_sz, const oop old, const uint age) {
177 HeapWord* obj = to_space_alloc_buffer()->allocate_aligned(word_sz, SurvivorAlignmentInBytes);
178 if (obj != NULL) {
179 return obj;
180 } else {
181 return alloc_in_to_space_slow(word_sz, old, age);
182 }
183 }
184
185 HeapWord* young_old_boundary() { return _young_old_boundary; }
186
187 void set_young_old_boundary(HeapWord *boundary) {
188 _young_old_boundary = boundary;
189 }
190
191 // Undo the most recent allocation ("obj", of "word_sz").
192 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
193
194 // Promotion failure stats
195 void register_promotion_failure(size_t sz) {
196 _promotion_failed_info.register_copy_failure(sz);
197 }
198 PromotionFailedInfo& promotion_failed_info() {
199 return _promotion_failed_info;
200 }
201 bool promotion_failed() {
202 return _promotion_failed_info.has_failed();
203 }
204 void print_promotion_failure_size();
205
206 #if TASKQUEUE_STATS
207 TaskQueueStats & taskqueue_stats() const { return _work_queue->stats; }
208
209 size_t term_attempts() const { return _term_attempts; }
210 size_t overflow_refills() const { return _overflow_refills; }
211 size_t overflow_refill_objs() const { return _overflow_refill_objs; }
212
213 void note_term_attempt() { ++_term_attempts; }
214 void note_overflow_refill(size_t objs) {
215 ++_overflow_refills; _overflow_refill_objs += objs;
216 }
217
218 void reset_stats();
219 #endif // TASKQUEUE_STATS
220
221 void start_strong_roots() {
222 _start_strong_roots = os::elapsedTime();
223 }
224 void end_strong_roots() {
225 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
226 }
227 double strong_roots_time() const { return _strong_roots_time; }
228 void start_term_time() {
229 TASKQUEUE_STATS_ONLY(note_term_attempt());
230 _start_term = os::elapsedTime();
231 }
232 void end_term_time() {
233 _term_time += (os::elapsedTime() - _start_term);
234 }
235 double term_time() const { return _term_time; }
236
237 double elapsed_time() const {
238 return os::elapsedTime() - _start;
239 }
240 };
241
242 class ParNewGenTask: public AbstractGangTask {
243 private:
244 ParNewGeneration* _gen;
245 Generation* _next_gen;
246 HeapWord* _young_old_boundary;
247 class ParScanThreadStateSet* _state_set;
248
249 public:
250 ParNewGenTask(ParNewGeneration* gen,
251 Generation* next_gen,
252 HeapWord* young_old_boundary,
253 ParScanThreadStateSet* state_set);
254
255 HeapWord* young_old_boundary() { return _young_old_boundary; }
256
257 void work(uint worker_id);
258
259 // Reset the terminator in ParScanThreadStateSet for
260 // "active_workers" threads.
261 virtual void set_for_termination(int active_workers);
262 };
263
264 class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
265 protected:
266 template <class T> void do_oop_work(T* p);
267 public:
268 KeepAliveClosure(ScanWeakRefClosure* cl);
269 virtual void do_oop(oop* p);
270 virtual void do_oop(narrowOop* p);
271 };
272
273 class EvacuateFollowersClosureGeneral: public VoidClosure {
274 private:
275 GenCollectedHeap* _gch;
276 int _level;
277 OopsInGenClosure* _scan_cur_or_nonheap;
278 OopsInGenClosure* _scan_older;
279 public:
280 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level,
281 OopsInGenClosure* cur,
282 OopsInGenClosure* older);
283 virtual void do_void();
284 };
285
286 // Closure for scanning ParNewGeneration.
287 // Same as ScanClosure, except does parallel GC barrier.
288 class ScanClosureWithParBarrier: public ScanClosure {
289 protected:
290 template <class T> void do_oop_work(T* p);
291 public:
292 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
293 virtual void do_oop(oop* p);
294 virtual void do_oop(narrowOop* p);
295 };
296
297 // Implements AbstractRefProcTaskExecutor for ParNew.
298 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
299 private:
300 ParNewGeneration& _generation;
301 ParScanThreadStateSet& _state_set;
302 public:
303 ParNewRefProcTaskExecutor(ParNewGeneration& generation,
304 ParScanThreadStateSet& state_set)
305 : _generation(generation), _state_set(state_set)
306 { }
307
308 // Executes a task using worker threads.
309 virtual void execute(ProcessTask& task);
310 virtual void execute(EnqueueTask& task);
311 // Switch to single threaded mode.
312 virtual void set_single_threaded_mode();
313 };
314
315
316 // A Generation that does parallel young-gen collection.
317
318 class ParNewGeneration: public DefNewGeneration {
319 friend class ParNewGenTask;
320 friend class ParNewRefProcTask;
321 friend class ParNewRefProcTaskExecutor;
322 friend class ParScanThreadStateSet;
323 friend class ParEvacuateFollowersClosure;
324
325 private:
326 // The per-worker-thread work queues
327 ObjToScanQueueSet* _task_queues;
328
329 // Per-worker-thread local overflow stacks
330 Stack<oop, mtGC>* _overflow_stacks;
331
332 // Desired size of survivor space plab's
333 PLABStats _plab_stats;
334
335 // A list of from-space images of to-be-scanned objects, threaded through
336 // klass-pointers (klass information already copied to the forwarded
337 // image.) Manipulated with CAS.
338 oop _overflow_list;
339 NOT_PRODUCT(ssize_t _num_par_pushes;)
340
341 // If true, older generation does not support promotion undo, so avoid.
342 static bool _avoid_promotion_undo;
343
344 // This closure is used by the reference processor to filter out
345 // references to live referent.
346 DefNewGeneration::IsAliveClosure _is_alive_closure;
347
348 static oop real_forwardee_slow(oop obj);
349 static void waste_some_time();
350
351 // Preserve the mark of "obj", if necessary, in preparation for its mark
352 // word being overwritten with a self-forwarding-pointer.
353 void preserve_mark_if_necessary(oop obj, markOop m);
354
355 void handle_promotion_failed(GenCollectedHeap* gch, ParScanThreadStateSet& thread_state_set, ParNewTracer& gc_tracer);
356
357 protected:
358
359 bool _survivor_overflow;
360
361 bool avoid_promotion_undo() { return _avoid_promotion_undo; }
362 void set_avoid_promotion_undo(bool v) { _avoid_promotion_undo = v; }
363
364 bool survivor_overflow() { return _survivor_overflow; }
365 void set_survivor_overflow(bool v) { _survivor_overflow = v; }
366
367 public:
368 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level);
369
370 ~ParNewGeneration() {
371 for (uint i = 0; i < ParallelGCThreads; i++)
372 delete _task_queues->queue(i);
373
374 delete _task_queues;
375 }
376
377 virtual void ref_processor_init();
378 virtual Generation::Name kind() { return Generation::ParNew; }
379 virtual const char* name() const;
380 virtual const char* short_name() const { return "ParNew"; }
381
382 // override
383 virtual bool refs_discovery_is_mt() const {
384 assert(UseParNewGC, "ParNewGeneration only when UseParNewGC");
385 return ParallelGCThreads > 1;
386 }
387
388 // Make the collection virtual.
389 virtual void collect(bool full,
390 bool clear_all_soft_refs,
391 size_t size,
392 bool is_tlab);
393
394 // This needs to be visible to the closure function.
395 // "obj" is the object to be copied, "m" is a recent value of its mark
396 // that must not contain a forwarding pointer (though one might be
397 // inserted in "obj"s mark word by a parallel thread).
398 inline oop copy_to_survivor_space(ParScanThreadState* par_scan_state,
399 oop obj, size_t obj_sz, markOop m) {
400 if (_avoid_promotion_undo) {
401 return copy_to_survivor_space_avoiding_promotion_undo(par_scan_state,
402 obj, obj_sz, m);
403 }
404
405 return copy_to_survivor_space_with_undo(par_scan_state, obj, obj_sz, m);
406 }
407
408 oop copy_to_survivor_space_avoiding_promotion_undo(ParScanThreadState* par_scan_state,
409 oop obj, size_t obj_sz, markOop m);
410
411 oop copy_to_survivor_space_with_undo(ParScanThreadState* par_scan_state,
412 oop obj, size_t obj_sz, markOop m);
413
414 // in support of testing overflow code
415 NOT_PRODUCT(int _overflow_counter;)
416 NOT_PRODUCT(bool should_simulate_overflow();)
417
418 // Accessor for overflow list
419 oop overflow_list() { return _overflow_list; }
420
421 // Push the given (from-space) object on the global overflow list.
422 void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state);
423
424 // If the global overflow list is non-empty, move some tasks from it
425 // onto "work_q" (which need not be empty). No more than 1/4 of the
426 // available space on "work_q" is used.
427 bool take_from_overflow_list(ParScanThreadState* par_scan_state);
428 bool take_from_overflow_list_work(ParScanThreadState* par_scan_state);
429
430 // The task queues to be used by parallel GC threads.
431 ObjToScanQueueSet* task_queues() {
432 return _task_queues;
433 }
434
435 PLABStats* plab_stats() {
436 return &_plab_stats;
437 }
438
439 size_t desired_plab_sz() {
440 return _plab_stats.desired_plab_sz();
441 }
442
443 static oop real_forwardee(oop obj);
444
445 DEBUG_ONLY(static bool is_legal_forward_ptr(oop p);)
446 };
447
448 #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARNEWGENERATION_HPP