Mon, 14 Jan 2013 21:30:45 +0100
8005972: ParNew should not update the tenuring threshold when promotion failed has occurred
Reviewed-by: ysr, johnc, jwilhelm
1 /*
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARNEWGENERATION_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARNEWGENERATION_HPP
28 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
29 #include "memory/defNewGeneration.hpp"
30 #include "utilities/taskqueue.hpp"
32 class ChunkArray;
33 class ParScanWithoutBarrierClosure;
34 class ParScanWithBarrierClosure;
35 class ParRootScanWithoutBarrierClosure;
36 class ParRootScanWithBarrierTwoGensClosure;
37 class ParEvacuateFollowersClosure;
39 // It would be better if these types could be kept local to the .cpp file,
40 // but they must be here to allow ParScanClosure::do_oop_work to be defined
41 // in genOopClosures.inline.hpp.
43 typedef Padded<OopTaskQueue> ObjToScanQueue;
44 typedef GenericTaskQueueSet<ObjToScanQueue, mtGC> ObjToScanQueueSet;
46 class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
47 private:
48 ParScanWeakRefClosure* _par_cl;
49 protected:
50 template <class T> void do_oop_work(T* p);
51 public:
52 ParKeepAliveClosure(ParScanWeakRefClosure* cl);
53 virtual void do_oop(oop* p);
54 virtual void do_oop(narrowOop* p);
55 };
57 // The state needed by thread performing parallel young-gen collection.
58 class ParScanThreadState {
59 friend class ParScanThreadStateSet;
60 private:
61 ObjToScanQueue *_work_queue;
62 Stack<oop, mtGC>* const _overflow_stack;
64 ParGCAllocBuffer _to_space_alloc_buffer;
66 ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier
67 ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier
68 ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier
69 // One of these two will be passed to process_strong_roots, which will
70 // set its generation. The first is for two-gen configs where the
71 // old gen collects the perm gen; the second is for arbitrary configs.
72 // The second isn't used right now (it used to be used for the train, an
73 // incremental collector) but the declaration has been left as a reminder.
74 ParRootScanWithBarrierTwoGensClosure _older_gen_closure;
75 // This closure will always be bound to the old gen; it will be used
76 // in evacuate_followers.
77 ParRootScanWithBarrierTwoGensClosure _old_gen_root_closure; // scan_old_root_with_gc_barrier
78 ParEvacuateFollowersClosure _evacuate_followers;
79 DefNewGeneration::IsAliveClosure _is_alive_closure;
80 ParScanWeakRefClosure _scan_weak_ref_closure;
81 ParKeepAliveClosure _keep_alive_closure;
84 Space* _to_space;
85 Space* to_space() { return _to_space; }
87 ParNewGeneration* _young_gen;
88 ParNewGeneration* young_gen() const { return _young_gen; }
90 Generation* _old_gen;
91 Generation* old_gen() { return _old_gen; }
93 HeapWord *_young_old_boundary;
95 int _hash_seed;
96 int _thread_num;
97 ageTable _ageTable;
99 bool _to_space_full;
101 #if TASKQUEUE_STATS
102 size_t _term_attempts;
103 size_t _overflow_refills;
104 size_t _overflow_refill_objs;
105 #endif // TASKQUEUE_STATS
107 // Stats for promotion failure
108 size_t _promotion_failure_size;
110 // Timing numbers.
111 double _start;
112 double _start_strong_roots;
113 double _strong_roots_time;
114 double _start_term;
115 double _term_time;
117 // Helper for trim_queues. Scans subset of an array and makes
118 // remainder available for work stealing.
119 void scan_partial_array_and_push_remainder(oop obj);
121 // In support of CMS' parallel rescan of survivor space.
122 ChunkArray* _survivor_chunk_array;
123 ChunkArray* survivor_chunk_array() { return _survivor_chunk_array; }
125 void record_survivor_plab(HeapWord* plab_start, size_t plab_word_size);
127 ParScanThreadState(Space* to_space_, ParNewGeneration* gen_,
128 Generation* old_gen_, int thread_num_,
129 ObjToScanQueueSet* work_queue_set_,
130 Stack<oop, mtGC>* overflow_stacks_,
131 size_t desired_plab_sz_,
132 ParallelTaskTerminator& term_);
134 public:
135 ageTable* age_table() {return &_ageTable;}
137 ObjToScanQueue* work_queue() { return _work_queue; }
139 ParGCAllocBuffer* to_space_alloc_buffer() {
140 return &_to_space_alloc_buffer;
141 }
143 ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; }
144 DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; }
145 ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; }
146 ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; }
147 ParScanClosure& older_gen_closure() { return _older_gen_closure; }
148 ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; };
150 // Decrease queue size below "max_size".
151 void trim_queues(int max_size);
153 // Private overflow stack usage
154 Stack<oop, mtGC>* overflow_stack() { return _overflow_stack; }
155 bool take_from_overflow_stack();
156 void push_on_overflow_stack(oop p);
158 // Is new_obj a candidate for scan_partial_array_and_push_remainder method.
159 inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const;
161 int* hash_seed() { return &_hash_seed; }
162 int thread_num() { return _thread_num; }
164 // Allocate a to-space block of size "sz", or else return NULL.
165 HeapWord* alloc_in_to_space_slow(size_t word_sz);
167 HeapWord* alloc_in_to_space(size_t word_sz) {
168 HeapWord* obj = to_space_alloc_buffer()->allocate(word_sz);
169 if (obj != NULL) return obj;
170 else return alloc_in_to_space_slow(word_sz);
171 }
173 HeapWord* young_old_boundary() { return _young_old_boundary; }
175 void set_young_old_boundary(HeapWord *boundary) {
176 _young_old_boundary = boundary;
177 }
179 // Undo the most recent allocation ("obj", of "word_sz").
180 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
182 // Promotion failure stats
183 size_t promotion_failure_size() { return promotion_failure_size(); }
184 void log_promotion_failure(size_t sz) {
185 if (_promotion_failure_size == 0) {
186 _promotion_failure_size = sz;
187 }
188 }
189 void print_and_clear_promotion_failure_size();
191 #if TASKQUEUE_STATS
192 TaskQueueStats & taskqueue_stats() const { return _work_queue->stats; }
194 size_t term_attempts() const { return _term_attempts; }
195 size_t overflow_refills() const { return _overflow_refills; }
196 size_t overflow_refill_objs() const { return _overflow_refill_objs; }
198 void note_term_attempt() { ++_term_attempts; }
199 void note_overflow_refill(size_t objs) {
200 ++_overflow_refills; _overflow_refill_objs += objs;
201 }
203 void reset_stats();
204 #endif // TASKQUEUE_STATS
206 void start_strong_roots() {
207 _start_strong_roots = os::elapsedTime();
208 }
209 void end_strong_roots() {
210 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
211 }
212 double strong_roots_time() const { return _strong_roots_time; }
213 void start_term_time() {
214 TASKQUEUE_STATS_ONLY(note_term_attempt());
215 _start_term = os::elapsedTime();
216 }
217 void end_term_time() {
218 _term_time += (os::elapsedTime() - _start_term);
219 }
220 double term_time() const { return _term_time; }
222 double elapsed_time() const {
223 return os::elapsedTime() - _start;
224 }
225 };
227 class ParNewGenTask: public AbstractGangTask {
228 private:
229 ParNewGeneration* _gen;
230 Generation* _next_gen;
231 HeapWord* _young_old_boundary;
232 class ParScanThreadStateSet* _state_set;
234 public:
235 ParNewGenTask(ParNewGeneration* gen,
236 Generation* next_gen,
237 HeapWord* young_old_boundary,
238 ParScanThreadStateSet* state_set);
240 HeapWord* young_old_boundary() { return _young_old_boundary; }
242 void work(uint worker_id);
244 // Reset the terminator in ParScanThreadStateSet for
245 // "active_workers" threads.
246 virtual void set_for_termination(int active_workers);
247 };
249 class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
250 protected:
251 template <class T> void do_oop_work(T* p);
252 public:
253 KeepAliveClosure(ScanWeakRefClosure* cl);
254 virtual void do_oop(oop* p);
255 virtual void do_oop(narrowOop* p);
256 };
258 class EvacuateFollowersClosureGeneral: public VoidClosure {
259 private:
260 GenCollectedHeap* _gch;
261 int _level;
262 OopsInGenClosure* _scan_cur_or_nonheap;
263 OopsInGenClosure* _scan_older;
264 public:
265 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level,
266 OopsInGenClosure* cur,
267 OopsInGenClosure* older);
268 virtual void do_void();
269 };
271 // Closure for scanning ParNewGeneration.
272 // Same as ScanClosure, except does parallel GC barrier.
273 class ScanClosureWithParBarrier: public ScanClosure {
274 protected:
275 template <class T> void do_oop_work(T* p);
276 public:
277 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
278 virtual void do_oop(oop* p);
279 virtual void do_oop(narrowOop* p);
280 };
282 // Implements AbstractRefProcTaskExecutor for ParNew.
283 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
284 private:
285 ParNewGeneration& _generation;
286 ParScanThreadStateSet& _state_set;
287 public:
288 ParNewRefProcTaskExecutor(ParNewGeneration& generation,
289 ParScanThreadStateSet& state_set)
290 : _generation(generation), _state_set(state_set)
291 { }
293 // Executes a task using worker threads.
294 virtual void execute(ProcessTask& task);
295 virtual void execute(EnqueueTask& task);
296 // Switch to single threaded mode.
297 virtual void set_single_threaded_mode();
298 };
301 // A Generation that does parallel young-gen collection.
303 class ParNewGeneration: public DefNewGeneration {
304 friend class ParNewGenTask;
305 friend class ParNewRefProcTask;
306 friend class ParNewRefProcTaskExecutor;
307 friend class ParScanThreadStateSet;
308 friend class ParEvacuateFollowersClosure;
310 private:
311 // The per-worker-thread work queues
312 ObjToScanQueueSet* _task_queues;
314 // Per-worker-thread local overflow stacks
315 Stack<oop, mtGC>* _overflow_stacks;
317 // Desired size of survivor space plab's
318 PLABStats _plab_stats;
320 // A list of from-space images of to-be-scanned objects, threaded through
321 // klass-pointers (klass information already copied to the forwarded
322 // image.) Manipulated with CAS.
323 oop _overflow_list;
324 NOT_PRODUCT(ssize_t _num_par_pushes;)
326 // If true, older generation does not support promotion undo, so avoid.
327 static bool _avoid_promotion_undo;
329 // This closure is used by the reference processor to filter out
330 // references to live referent.
331 DefNewGeneration::IsAliveClosure _is_alive_closure;
333 static oop real_forwardee_slow(oop obj);
334 static void waste_some_time();
336 // Preserve the mark of "obj", if necessary, in preparation for its mark
337 // word being overwritten with a self-forwarding-pointer.
338 void preserve_mark_if_necessary(oop obj, markOop m);
340 protected:
342 bool _survivor_overflow;
344 bool avoid_promotion_undo() { return _avoid_promotion_undo; }
345 void set_avoid_promotion_undo(bool v) { _avoid_promotion_undo = v; }
347 bool survivor_overflow() { return _survivor_overflow; }
348 void set_survivor_overflow(bool v) { _survivor_overflow = v; }
350 public:
351 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level);
353 ~ParNewGeneration() {
354 for (uint i = 0; i < ParallelGCThreads; i++)
355 delete _task_queues->queue(i);
357 delete _task_queues;
358 }
360 virtual void ref_processor_init();
361 virtual Generation::Name kind() { return Generation::ParNew; }
362 virtual const char* name() const;
363 virtual const char* short_name() const { return "ParNew"; }
365 // override
366 virtual bool refs_discovery_is_mt() const {
367 assert(UseParNewGC, "ParNewGeneration only when UseParNewGC");
368 return ParallelGCThreads > 1;
369 }
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);
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 inline oop copy_to_survivor_space(ParScanThreadState* par_scan_state,
382 oop obj, size_t obj_sz, markOop m) {
383 if (_avoid_promotion_undo) {
384 return copy_to_survivor_space_avoiding_promotion_undo(par_scan_state,
385 obj, obj_sz, m);
386 }
388 return copy_to_survivor_space_with_undo(par_scan_state, obj, obj_sz, m);
389 }
391 oop copy_to_survivor_space_avoiding_promotion_undo(ParScanThreadState* par_scan_state,
392 oop obj, size_t obj_sz, markOop m);
394 oop copy_to_survivor_space_with_undo(ParScanThreadState* par_scan_state,
395 oop obj, size_t obj_sz, markOop m);
397 // in support of testing overflow code
398 NOT_PRODUCT(int _overflow_counter;)
399 NOT_PRODUCT(bool should_simulate_overflow();)
401 // Accessor for overflow list
402 oop overflow_list() { return _overflow_list; }
404 // Push the given (from-space) object on the global overflow list.
405 void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state);
407 // If the global overflow list is non-empty, move some tasks from it
408 // onto "work_q" (which need not be empty). No more than 1/4 of the
409 // available space on "work_q" is used.
410 bool take_from_overflow_list(ParScanThreadState* par_scan_state);
411 bool take_from_overflow_list_work(ParScanThreadState* par_scan_state);
413 // The task queues to be used by parallel GC threads.
414 ObjToScanQueueSet* task_queues() {
415 return _task_queues;
416 }
418 PLABStats* plab_stats() {
419 return &_plab_stats;
420 }
422 size_t desired_plab_sz() {
423 return _plab_stats.desired_plab_sz();
424 }
426 static oop real_forwardee(oop obj);
428 DEBUG_ONLY(static bool is_legal_forward_ptr(oop p);)
429 };
431 #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARNEWGENERATION_HPP