1 /* 2 * Copyright (c) 2001, 2015, 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_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/plab.hpp" 33 #include "gc/shared/taskqueue.hpp" 34 #include "memory/padded.hpp" 35 36 class ChunkArray; 37 class ParScanWithoutBarrierClosure; 38 class ParScanWithBarrierClosure; 39 class ParRootScanWithoutBarrierClosure; 40 class ParRootScanWithBarrierTwoGensClosure; 41 class ParEvacuateFollowersClosure; 42 class StrongRootsScope; 43 44 // It would be better if these types could be kept local to the .cpp file, 45 // but they must be here to allow ParScanClosure::do_oop_work to be defined 46 // in genOopClosures.inline.hpp. 47 48 typedef Padded<OopTaskQueue> ObjToScanQueue; 49 typedef GenericTaskQueueSet<ObjToScanQueue, mtGC> ObjToScanQueueSet; 50 51 class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure { 52 private: 53 ParScanWeakRefClosure* _par_cl; 54 protected: 55 template <class T> void do_oop_work(T* p); 56 public: 57 ParKeepAliveClosure(ParScanWeakRefClosure* cl); 58 virtual void do_oop(oop* p); 59 virtual void do_oop(narrowOop* p); 60 }; 61 62 // The state needed by thread performing parallel young-gen collection. 63 class ParScanThreadState { 64 friend class ParScanThreadStateSet; 65 private: 66 ObjToScanQueue *_work_queue; 67 Stack<oop, mtGC>* const _overflow_stack; 68 69 PLAB _to_space_alloc_buffer; 70 71 ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier 72 ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier 73 ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier 74 // One of these two will be passed to process_roots, which will 75 // set its generation. The first is for two-gen configs where the 76 // old gen collects the perm gen; the second is for arbitrary configs. 77 // The second isn't used right now (it used to be used for the train, an 78 // incremental collector) but the declaration has been left as a reminder. 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 89 Space* _to_space; 90 Space* to_space() { return _to_space; } 91 92 ParNewGeneration* _young_gen; 93 ParNewGeneration* young_gen() const { return _young_gen; } 94 95 Generation* _old_gen; 96 Generation* old_gen() { return _old_gen; } 97 98 HeapWord *_young_old_boundary; 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 ParallelTaskTerminator& term_); 138 139 public: 140 ageTable* age_table() {return &_ageTable;} 141 142 ObjToScanQueue* work_queue() { return _work_queue; } 143 144 PLAB* to_space_alloc_buffer() { 145 return &_to_space_alloc_buffer; 146 } 147 148 ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; } 149 DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; } 150 ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; } 151 ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; } 152 ParScanClosure& older_gen_closure() { return _older_gen_closure; } 153 ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; }; 154 155 // Decrease queue size below "max_size". 156 void trim_queues(int max_size); 157 158 // Private overflow stack usage 159 Stack<oop, mtGC>* overflow_stack() { return _overflow_stack; } 160 bool take_from_overflow_stack(); 161 void push_on_overflow_stack(oop p); 162 163 // Is new_obj a candidate for scan_partial_array_and_push_remainder method. 164 inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const; 165 166 int* hash_seed() { return &_hash_seed; } 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 HeapWord* alloc_in_to_space(size_t word_sz) { 173 HeapWord* obj = to_space_alloc_buffer()->allocate_aligned(word_sz, SurvivorAlignmentInBytes); 174 if (obj != NULL) return obj; 175 else return alloc_in_to_space_slow(word_sz); 176 } 177 178 HeapWord* young_old_boundary() { return _young_old_boundary; } 179 180 void set_young_old_boundary(HeapWord *boundary) { 181 _young_old_boundary = boundary; 182 } 183 184 // Undo the most recent allocation ("obj", of "word_sz"). 185 void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz); 186 187 // Promotion failure stats 188 void register_promotion_failure(size_t sz) { 189 _promotion_failed_info.register_copy_failure(sz); 190 } 191 PromotionFailedInfo& promotion_failed_info() { 192 return _promotion_failed_info; 193 } 194 bool promotion_failed() { 195 return _promotion_failed_info.has_failed(); 196 } 197 void print_promotion_failure_size(); 198 199 #if TASKQUEUE_STATS 200 TaskQueueStats & taskqueue_stats() const { return _work_queue->stats; } 201 202 size_t term_attempts() const { return _term_attempts; } 203 size_t overflow_refills() const { return _overflow_refills; } 204 size_t overflow_refill_objs() const { return _overflow_refill_objs; } 205 206 void note_term_attempt() { ++_term_attempts; } 207 void note_overflow_refill(size_t objs) { 208 ++_overflow_refills; _overflow_refill_objs += objs; 209 } 210 211 void reset_stats(); 212 #endif // TASKQUEUE_STATS 213 214 void start_strong_roots() { 215 _start_strong_roots = os::elapsedTime(); 216 } 217 void end_strong_roots() { 218 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 219 } 220 double strong_roots_time() const { return _strong_roots_time; } 221 void start_term_time() { 222 TASKQUEUE_STATS_ONLY(note_term_attempt()); 223 _start_term = os::elapsedTime(); 224 } 225 void end_term_time() { 226 _term_time += (os::elapsedTime() - _start_term); 227 } 228 double term_time() const { return _term_time; } 229 230 double elapsed_time() const { 231 return os::elapsedTime() - _start; 232 } 233 }; 234 235 class ParNewGenTask: public AbstractGangTask { 236 private: 237 ParNewGeneration* _gen; 238 Generation* _old_gen; 239 HeapWord* _young_old_boundary; 240 class ParScanThreadStateSet* _state_set; 241 StrongRootsScope* _strong_roots_scope; 242 243 public: 244 ParNewGenTask(ParNewGeneration* gen, 245 Generation* old_gen, 246 HeapWord* young_old_boundary, 247 ParScanThreadStateSet* state_set, 248 StrongRootsScope* strong_roots_scope); 249 250 HeapWord* young_old_boundary() { return _young_old_boundary; } 251 252 void work(uint worker_id); 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 // This closure is used by the reference processor to filter out 333 // references to live referent. 334 DefNewGeneration::IsAliveClosure _is_alive_closure; 335 336 // GC tracer that should be used during collection. 337 ParNewTracer _gc_tracer; 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); 347 348 protected: 349 350 bool _survivor_overflow; 351 352 bool survivor_overflow() { return _survivor_overflow; } 353 void set_survivor_overflow(bool v) { _survivor_overflow = v; } 354 355 public: 356 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level); 357 358 ~ParNewGeneration() { 359 for (uint i = 0; i < ParallelGCThreads; i++) 360 delete _task_queues->queue(i); 361 362 delete _task_queues; 363 } 364 365 virtual void ref_processor_init(); 366 virtual Generation::Name kind() { return Generation::ParNew; } 367 virtual const char* name() const; 368 virtual const char* short_name() const { return "ParNew"; } 369 370 // override 371 virtual bool refs_discovery_is_mt() const { 372 return ParallelGCThreads > 1; 373 } 374 375 // Make the collection virtual. 376 virtual void collect(bool full, 377 bool clear_all_soft_refs, 378 size_t size, 379 bool is_tlab); 380 381 // This needs to be visible to the closure function. 382 // "obj" is the object to be copied, "m" is a recent value of its mark 383 // that must not contain a forwarding pointer (though one might be 384 // inserted in "obj"s mark word by a parallel thread). 385 oop copy_to_survivor_space(ParScanThreadState* par_scan_state, 386 oop obj, size_t obj_sz, markOop m); 387 388 // in support of testing overflow code 389 NOT_PRODUCT(int _overflow_counter;) 390 NOT_PRODUCT(bool should_simulate_overflow();) 391 392 // Accessor for overflow list 393 oop overflow_list() { return _overflow_list; } 394 395 // Push the given (from-space) object on the global overflow list. 396 void push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state); 397 398 // If the global overflow list is non-empty, move some tasks from it 399 // onto "work_q" (which need not be empty). No more than 1/4 of the 400 // available space on "work_q" is used. 401 bool take_from_overflow_list(ParScanThreadState* par_scan_state); 402 bool take_from_overflow_list_work(ParScanThreadState* par_scan_state); 403 404 // The task queues to be used by parallel GC threads. 405 ObjToScanQueueSet* task_queues() { 406 return _task_queues; 407 } 408 409 PLABStats* plab_stats() { 410 return &_plab_stats; 411 } 412 413 size_t desired_plab_sz() { 414 return _plab_stats.desired_plab_sz(); 415 } 416 417 const ParNewTracer* gc_tracer() const { 418 return &_gc_tracer; 419 } 420 421 static oop real_forwardee(oop obj); 422 }; 423 424 #endif // SHARE_VM_GC_CMS_PARNEWGENERATION_HPP