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 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