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. 22 * 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 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 size_t desired_plab_sz_, 135 ParallelTaskTerminator& term_); 136 137 public: 138 ageTable* age_table() {return &_ageTable;} 139 140 ObjToScanQueue* work_queue() { return _work_queue; } 141 142 ParGCAllocBuffer* to_space_alloc_buffer() { 143 return &_to_space_alloc_buffer; 144 } 145 146 ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; } 147 DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; } 148 ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; } 149 ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; } 150 ParScanClosure& older_gen_closure() { return _older_gen_closure; } 151 ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; }; 152 153 // Decrease queue size below "max_size". 154 void trim_queues(int max_size); 155 156 // Private overflow stack usage 157 Stack<oop, mtGC>* overflow_stack() { return _overflow_stack; } 158 bool take_from_overflow_stack(); 159 void push_on_overflow_stack(oop p); 160 161 // Is new_obj a candidate for scan_partial_array_and_push_remainder method. 162 inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const; 163 164 int* hash_seed() { return &_hash_seed; } 165 int thread_num() { return _thread_num; } 166 167 // Allocate a to-space block of size "sz", or else return NULL. 168 HeapWord* alloc_in_to_space_slow(size_t word_sz); 169 170 HeapWord* alloc_in_to_space(size_t word_sz) { 171 HeapWord* obj = to_space_alloc_buffer()->allocate(word_sz); 172 if (obj != NULL) return obj; 173 else return alloc_in_to_space_slow(word_sz); 174 } 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* _gen; 236 Generation* _next_gen; 237 HeapWord* _young_old_boundary; 238 class ParScanThreadStateSet* _state_set; 239 240 public: 241 ParNewGenTask(ParNewGeneration* gen, 242 Generation* next_gen, 243 HeapWord* young_old_boundary, 244 ParScanThreadStateSet* state_set); 245 246 HeapWord* young_old_boundary() { return _young_old_boundary; } 247 248 void work(uint worker_id); 249 250 // Reset the terminator in ParScanThreadStateSet for 251 // "active_workers" threads. 252 virtual void set_for_termination(int active_workers); 253 }; 254 255 class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure { 256 protected: 257 template <class T> void do_oop_work(T* p); 258 public: 259 KeepAliveClosure(ScanWeakRefClosure* cl); 260 virtual void do_oop(oop* p); 261 virtual void do_oop(narrowOop* p); 262 }; 263 264 class EvacuateFollowersClosureGeneral: public VoidClosure { 265 private: 266 GenCollectedHeap* _gch; 267 int _level; 268 OopsInGenClosure* _scan_cur_or_nonheap; 269 OopsInGenClosure* _scan_older; 270 public: 271 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level, 272 OopsInGenClosure* cur, 273 OopsInGenClosure* older); 274 virtual void do_void(); 275 }; 276 277 // Closure for scanning ParNewGeneration. 278 // Same as ScanClosure, except does parallel GC barrier. 279 class ScanClosureWithParBarrier: public ScanClosure { 280 protected: 281 template <class T> void do_oop_work(T* p); 282 public: 283 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier); 284 virtual void do_oop(oop* p); 285 virtual void do_oop(narrowOop* p); 286 }; 287 288 // Implements AbstractRefProcTaskExecutor for ParNew. 289 class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 290 private: 291 ParNewGeneration& _generation; 292 ParScanThreadStateSet& _state_set; 293 public: 294 ParNewRefProcTaskExecutor(ParNewGeneration& generation, 295 ParScanThreadStateSet& state_set) 296 : _generation(generation), _state_set(state_set) 297 { } 298 299 // Executes a task using worker threads. 300 virtual void execute(ProcessTask& task); 301 virtual void execute(EnqueueTask& 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 oop _overflow_list; 330 NOT_PRODUCT(ssize_t _num_par_pushes;) 331 332 // If true, older generation does not support promotion undo, so avoid. 333 static bool _avoid_promotion_undo; 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 static oop real_forwardee_slow(oop obj); 340 static void waste_some_time(); 341 342 // Preserve the mark of "obj", if necessary, in preparation for its mark 343 // word being overwritten with a self-forwarding-pointer. 344 void preserve_mark_if_necessary(oop obj, markOop m); 345 346 void handle_promotion_failed(GenCollectedHeap* gch, ParScanThreadStateSet& thread_state_set, ParNewTracer& gc_tracer); 347 348 protected: 349 350 bool _survivor_overflow; 351 352 bool avoid_promotion_undo() { return _avoid_promotion_undo; } 353 void set_avoid_promotion_undo(bool v) { _avoid_promotion_undo = v; } 354 355 bool survivor_overflow() { return _survivor_overflow; } 356 void set_survivor_overflow(bool v) { _survivor_overflow = v; } 357 358 public: 359 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level); 360 361 ~ParNewGeneration() { 362 for (uint i = 0; i < ParallelGCThreads; i++) 363 delete _task_queues->queue(i); 364 365 delete _task_queues; 366 } 367 368 virtual void ref_processor_init(); 369 virtual Generation::Name kind() { return Generation::ParNew; } 370 virtual const char* name() const; 371 virtual const char* short_name() const { return "ParNew"; } 372 373 // override 374 virtual bool refs_discovery_is_mt() const { 375 assert(UseParNewGC, "ParNewGeneration only when UseParNewGC"); 376 return ParallelGCThreads > 1; 377 } 378 379 // Make the collection virtual. 380 virtual void collect(bool full, 381 bool clear_all_soft_refs, 382 size_t size, 383 bool is_tlab); 384 385 // This needs to be visible to the closure function. 386 // "obj" is the object to be copied, "m" is a recent value of its mark 387 // that must not contain a forwarding pointer (though one might be 388 // inserted in "obj"s mark word by a parallel thread). 389 inline oop copy_to_survivor_space(ParScanThreadState* par_scan_state, 390 oop obj, size_t obj_sz, markOop m) { 391 if (_avoid_promotion_undo) { 392 return copy_to_survivor_space_avoiding_promotion_undo(par_scan_state, 393 obj, obj_sz, m); 394 } 395 396 return copy_to_survivor_space_with_undo(par_scan_state, obj, obj_sz, m); 397 } 398 399 oop copy_to_survivor_space_avoiding_promotion_undo(ParScanThreadState* par_scan_state, 400 oop obj, size_t obj_sz, markOop m); 401 402 oop copy_to_survivor_space_with_undo(ParScanThreadState* par_scan_state, 403 oop obj, size_t obj_sz, markOop m); 404 405 // in support of testing overflow code 406 NOT_PRODUCT(int _overflow_counter;) 407 NOT_PRODUCT(bool should_simulate_overflow();) 408 409 // Accessor for overflow list 410 oop overflow_list() { return _overflow_list; } 411 412 // Push the given (from-space) object on the global overflow list. 413 void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state); 414 415 // If the global overflow list is non-empty, move some tasks from it 416 // onto "work_q" (which need not be empty). No more than 1/4 of the 417 // available space on "work_q" is used. 418 bool take_from_overflow_list(ParScanThreadState* par_scan_state); 419 bool take_from_overflow_list_work(ParScanThreadState* par_scan_state); 420 421 // The task queues to be used by parallel GC threads. 422 ObjToScanQueueSet* task_queues() { 423 return _task_queues; 424 } 425 426 PLABStats* plab_stats() { 427 return &_plab_stats; 428 } 429 430 size_t desired_plab_sz() { 431 return _plab_stats.desired_plab_sz(); 432 } 433 434 static oop real_forwardee(oop obj); 435 436 DEBUG_ONLY(static bool is_legal_forward_ptr(oop p);) 437 }; 438 439 #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARNEWGENERATION_HPP