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_CONCURRENTMARKSWEEP_CONCURRENTMARKSWEEPGENERATION_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CONCURRENTMARKSWEEPGENERATION_HPP 27 28 #include "gc_implementation/shared/gSpaceCounters.hpp" 29 #include "gc_implementation/shared/gcStats.hpp" 30 #include "gc_implementation/shared/generationCounters.hpp" 31 #include "memory/freeBlockDictionary.hpp" 32 #include "memory/generation.hpp" 33 #include "runtime/mutexLocker.hpp" 34 #include "runtime/virtualspace.hpp" 35 #include "services/memoryService.hpp" 36 #include "utilities/bitMap.inline.hpp" 37 #include "utilities/stack.inline.hpp" 38 #include "utilities/taskqueue.hpp" 39 #include "utilities/yieldingWorkgroup.hpp" 40 41 // ConcurrentMarkSweepGeneration is in support of a concurrent 42 // mark-sweep old generation in the Detlefs-Printezis--Boehm-Demers-Schenker 43 // style. We assume, for now, that this generation is always the 44 // seniormost generation and for simplicity 45 // in the first implementation, that this generation is a single compactible 46 // space. Neither of these restrictions appears essential, and will be 47 // relaxed in the future when more time is available to implement the 48 // greater generality (and there's a need for it). 49 // 50 // Concurrent mode failures are currently handled by 51 // means of a sliding mark-compact. 52 53 class CMSAdaptiveSizePolicy; 54 class CMSConcMarkingTask; 55 class CMSGCAdaptivePolicyCounters; 56 class ConcurrentMarkSweepGeneration; 57 class ConcurrentMarkSweepPolicy; 58 class ConcurrentMarkSweepThread; 59 class CompactibleFreeListSpace; 60 class FreeChunk; 61 class PromotionInfo; 62 class ScanMarkedObjectsAgainCarefullyClosure; 63 class TenuredGeneration; 64 65 // A generic CMS bit map. It's the basis for both the CMS marking bit map 66 // as well as for the mod union table (in each case only a subset of the 67 // methods are used). This is essentially a wrapper around the BitMap class, 68 // with one bit per (1<<_shifter) HeapWords. (i.e. for the marking bit map, 69 // we have _shifter == 0. and for the mod union table we have 70 // shifter == CardTableModRefBS::card_shift - LogHeapWordSize.) 71 // XXX 64-bit issues in BitMap? 72 class CMSBitMap VALUE_OBJ_CLASS_SPEC { 73 friend class VMStructs; 74 75 HeapWord* _bmStartWord; // base address of range covered by map 76 size_t _bmWordSize; // map size (in #HeapWords covered) 77 const int _shifter; // shifts to convert HeapWord to bit position 78 VirtualSpace _virtual_space; // underlying the bit map 79 BitMap _bm; // the bit map itself 80 public: 81 Mutex* const _lock; // mutex protecting _bm; 82 83 public: 84 // constructor 85 CMSBitMap(int shifter, int mutex_rank, const char* mutex_name); 86 87 // allocates the actual storage for the map 88 bool allocate(MemRegion mr); 89 // field getter 90 Mutex* lock() const { return _lock; } 91 // locking verifier convenience function 92 void assert_locked() const PRODUCT_RETURN; 93 94 // inquiries 95 HeapWord* startWord() const { return _bmStartWord; } 96 size_t sizeInWords() const { return _bmWordSize; } 97 size_t sizeInBits() const { return _bm.size(); } 98 // the following is one past the last word in space 99 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; } 100 101 // reading marks 102 bool isMarked(HeapWord* addr) const; 103 bool par_isMarked(HeapWord* addr) const; // do not lock checks 104 bool isUnmarked(HeapWord* addr) const; 105 bool isAllClear() const; 106 107 // writing marks 108 void mark(HeapWord* addr); 109 // For marking by parallel GC threads; 110 // returns true if we did, false if another thread did 111 bool par_mark(HeapWord* addr); 112 113 void mark_range(MemRegion mr); 114 void par_mark_range(MemRegion mr); 115 void mark_large_range(MemRegion mr); 116 void par_mark_large_range(MemRegion mr); 117 void par_clear(HeapWord* addr); // For unmarking by parallel GC threads. 118 void clear_range(MemRegion mr); 119 void par_clear_range(MemRegion mr); 120 void clear_large_range(MemRegion mr); 121 void par_clear_large_range(MemRegion mr); 122 void clear_all(); 123 void clear_all_incrementally(); // Not yet implemented!! 124 125 NOT_PRODUCT( 126 // checks the memory region for validity 127 void region_invariant(MemRegion mr); 128 ) 129 130 // iteration 131 void iterate(BitMapClosure* cl) { 132 _bm.iterate(cl); 133 } 134 void iterate(BitMapClosure* cl, HeapWord* left, HeapWord* right); 135 void dirty_range_iterate_clear(MemRegionClosure* cl); 136 void dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl); 137 138 // auxiliary support for iteration 139 HeapWord* getNextMarkedWordAddress(HeapWord* addr) const; 140 HeapWord* getNextMarkedWordAddress(HeapWord* start_addr, 141 HeapWord* end_addr) const; 142 HeapWord* getNextUnmarkedWordAddress(HeapWord* addr) const; 143 HeapWord* getNextUnmarkedWordAddress(HeapWord* start_addr, 144 HeapWord* end_addr) const; 145 MemRegion getAndClearMarkedRegion(HeapWord* addr); 146 MemRegion getAndClearMarkedRegion(HeapWord* start_addr, 147 HeapWord* end_addr); 148 149 // conversion utilities 150 HeapWord* offsetToHeapWord(size_t offset) const; 151 size_t heapWordToOffset(HeapWord* addr) const; 152 size_t heapWordDiffToOffsetDiff(size_t diff) const; 153 154 void print_on_error(outputStream* st, const char* prefix) const; 155 156 // debugging 157 // is this address range covered by the bit-map? 158 NOT_PRODUCT( 159 bool covers(MemRegion mr) const; 160 bool covers(HeapWord* start, size_t size = 0) const; 161 ) 162 void verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) PRODUCT_RETURN; 163 }; 164 165 // Represents a marking stack used by the CMS collector. 166 // Ideally this should be GrowableArray<> just like MSC's marking stack(s). 167 class CMSMarkStack: public CHeapObj<mtGC> { 168 // 169 friend class CMSCollector; // to get at expasion stats further below 170 // 171 172 VirtualSpace _virtual_space; // space for the stack 173 oop* _base; // bottom of stack 174 size_t _index; // one more than last occupied index 175 size_t _capacity; // max #elements 176 Mutex _par_lock; // an advisory lock used in case of parallel access 177 NOT_PRODUCT(size_t _max_depth;) // max depth plumbed during run 178 179 protected: 180 size_t _hit_limit; // we hit max stack size limit 181 size_t _failed_double; // we failed expansion before hitting limit 182 183 public: 184 CMSMarkStack(): 185 _par_lock(Mutex::event, "CMSMarkStack._par_lock", true), 186 _hit_limit(0), 187 _failed_double(0) {} 188 189 bool allocate(size_t size); 190 191 size_t capacity() const { return _capacity; } 192 193 oop pop() { 194 if (!isEmpty()) { 195 return _base[--_index] ; 196 } 197 return NULL; 198 } 199 200 bool push(oop ptr) { 201 if (isFull()) { 202 return false; 203 } else { 204 _base[_index++] = ptr; 205 NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index)); 206 return true; 207 } 208 } 209 210 bool isEmpty() const { return _index == 0; } 211 bool isFull() const { 212 assert(_index <= _capacity, "buffer overflow"); 213 return _index == _capacity; 214 } 215 216 size_t length() { return _index; } 217 218 // "Parallel versions" of some of the above 219 oop par_pop() { 220 // lock and pop 221 MutexLockerEx x(&_par_lock, Mutex::_no_safepoint_check_flag); 222 return pop(); 223 } 224 225 bool par_push(oop ptr) { 226 // lock and push 227 MutexLockerEx x(&_par_lock, Mutex::_no_safepoint_check_flag); 228 return push(ptr); 229 } 230 231 // Forcibly reset the stack, losing all of its contents. 232 void reset() { 233 _index = 0; 234 } 235 236 // Expand the stack, typically in response to an overflow condition 237 void expand(); 238 239 // Compute the least valued stack element. 240 oop least_value(HeapWord* low) { 241 oop least = (oop)low; 242 for (size_t i = 0; i < _index; i++) { 243 least = MIN2(least, _base[i]); 244 } 245 return least; 246 } 247 248 // Exposed here to allow stack expansion in || case 249 Mutex* par_lock() { return &_par_lock; } 250 }; 251 252 class CardTableRS; 253 class CMSParGCThreadState; 254 255 class ModUnionClosure: public MemRegionClosure { 256 protected: 257 CMSBitMap* _t; 258 public: 259 ModUnionClosure(CMSBitMap* t): _t(t) { } 260 void do_MemRegion(MemRegion mr); 261 }; 262 263 class ModUnionClosurePar: public ModUnionClosure { 264 public: 265 ModUnionClosurePar(CMSBitMap* t): ModUnionClosure(t) { } 266 void do_MemRegion(MemRegion mr); 267 }; 268 269 // Survivor Chunk Array in support of parallelization of 270 // Survivor Space rescan. 271 class ChunkArray: public CHeapObj<mtGC> { 272 size_t _index; 273 size_t _capacity; 274 size_t _overflows; 275 HeapWord** _array; // storage for array 276 277 public: 278 ChunkArray() : _index(0), _capacity(0), _overflows(0), _array(NULL) {} 279 ChunkArray(HeapWord** a, size_t c): 280 _index(0), _capacity(c), _overflows(0), _array(a) {} 281 282 HeapWord** array() { return _array; } 283 void set_array(HeapWord** a) { _array = a; } 284 285 size_t capacity() { return _capacity; } 286 void set_capacity(size_t c) { _capacity = c; } 287 288 size_t end() { 289 assert(_index <= capacity(), 290 err_msg("_index (" SIZE_FORMAT ") > _capacity (" SIZE_FORMAT "): out of bounds", 291 _index, _capacity)); 292 return _index; 293 } // exclusive 294 295 HeapWord* nth(size_t n) { 296 assert(n < end(), "Out of bounds access"); 297 return _array[n]; 298 } 299 300 void reset() { 301 _index = 0; 302 if (_overflows > 0 && PrintCMSStatistics > 1) { 303 warning("CMS: ChunkArray[" SIZE_FORMAT "] overflowed " SIZE_FORMAT " times", 304 _capacity, _overflows); 305 } 306 _overflows = 0; 307 } 308 309 void record_sample(HeapWord* p, size_t sz) { 310 // For now we do not do anything with the size 311 if (_index < _capacity) { 312 _array[_index++] = p; 313 } else { 314 ++_overflows; 315 assert(_index == _capacity, 316 err_msg("_index (" SIZE_FORMAT ") > _capacity (" SIZE_FORMAT 317 "): out of bounds at overflow#" SIZE_FORMAT, 318 _index, _capacity, _overflows)); 319 } 320 } 321 }; 322 323 // 324 // Timing, allocation and promotion statistics for gc scheduling and incremental 325 // mode pacing. Most statistics are exponential averages. 326 // 327 class CMSStats VALUE_OBJ_CLASS_SPEC { 328 private: 329 ConcurrentMarkSweepGeneration* const _cms_gen; // The cms (old) gen. 330 331 // The following are exponential averages with factor alpha: 332 // avg = (100 - alpha) * avg + alpha * cur_sample 333 // 334 // The durations measure: end_time[n] - start_time[n] 335 // The periods measure: start_time[n] - start_time[n-1] 336 // 337 // The cms period and duration include only concurrent collections; time spent 338 // in foreground cms collections due to System.gc() or because of a failure to 339 // keep up are not included. 340 // 341 // There are 3 alphas to "bootstrap" the statistics. The _saved_alpha is the 342 // real value, but is used only after the first period. A value of 100 is 343 // used for the first sample so it gets the entire weight. 344 unsigned int _saved_alpha; // 0-100 345 unsigned int _gc0_alpha; 346 unsigned int _cms_alpha; 347 348 double _gc0_duration; 349 double _gc0_period; 350 size_t _gc0_promoted; // bytes promoted per gc0 351 double _cms_duration; 352 double _cms_duration_pre_sweep; // time from initiation to start of sweep 353 double _cms_duration_per_mb; 354 double _cms_period; 355 size_t _cms_allocated; // bytes of direct allocation per gc0 period 356 357 // Timers. 358 elapsedTimer _cms_timer; 359 TimeStamp _gc0_begin_time; 360 TimeStamp _cms_begin_time; 361 TimeStamp _cms_end_time; 362 363 // Snapshots of the amount used in the CMS generation. 364 size_t _cms_used_at_gc0_begin; 365 size_t _cms_used_at_gc0_end; 366 size_t _cms_used_at_cms_begin; 367 368 // Used to prevent the duty cycle from being reduced in the middle of a cms 369 // cycle. 370 bool _allow_duty_cycle_reduction; 371 372 enum { 373 _GC0_VALID = 0x1, 374 _CMS_VALID = 0x2, 375 _ALL_VALID = _GC0_VALID | _CMS_VALID 376 }; 377 378 unsigned int _valid_bits; 379 380 unsigned int _icms_duty_cycle; // icms duty cycle (0-100). 381 382 protected: 383 384 // Return a duty cycle that avoids wild oscillations, by limiting the amount 385 // of change between old_duty_cycle and new_duty_cycle (the latter is treated 386 // as a recommended value). 387 static unsigned int icms_damped_duty_cycle(unsigned int old_duty_cycle, 388 unsigned int new_duty_cycle); 389 unsigned int icms_update_duty_cycle_impl(); 390 391 // In support of adjusting of cms trigger ratios based on history 392 // of concurrent mode failure. 393 double cms_free_adjustment_factor(size_t free) const; 394 void adjust_cms_free_adjustment_factor(bool fail, size_t free); 395 396 public: 397 CMSStats(ConcurrentMarkSweepGeneration* cms_gen, 398 unsigned int alpha = CMSExpAvgFactor); 399 400 // Whether or not the statistics contain valid data; higher level statistics 401 // cannot be called until this returns true (they require at least one young 402 // gen and one cms cycle to have completed). 403 bool valid() const; 404 405 // Record statistics. 406 void record_gc0_begin(); 407 void record_gc0_end(size_t cms_gen_bytes_used); 408 void record_cms_begin(); 409 void record_cms_end(); 410 411 // Allow management of the cms timer, which must be stopped/started around 412 // yield points. 413 elapsedTimer& cms_timer() { return _cms_timer; } 414 void start_cms_timer() { _cms_timer.start(); } 415 void stop_cms_timer() { _cms_timer.stop(); } 416 417 // Basic statistics; units are seconds or bytes. 418 double gc0_period() const { return _gc0_period; } 419 double gc0_duration() const { return _gc0_duration; } 420 size_t gc0_promoted() const { return _gc0_promoted; } 421 double cms_period() const { return _cms_period; } 422 double cms_duration() const { return _cms_duration; } 423 double cms_duration_per_mb() const { return _cms_duration_per_mb; } 424 size_t cms_allocated() const { return _cms_allocated; } 425 426 size_t cms_used_at_gc0_end() const { return _cms_used_at_gc0_end;} 427 428 // Seconds since the last background cms cycle began or ended. 429 double cms_time_since_begin() const; 430 double cms_time_since_end() const; 431 432 // Higher level statistics--caller must check that valid() returns true before 433 // calling. 434 435 // Returns bytes promoted per second of wall clock time. 436 double promotion_rate() const; 437 438 // Returns bytes directly allocated per second of wall clock time. 439 double cms_allocation_rate() const; 440 441 // Rate at which space in the cms generation is being consumed (sum of the 442 // above two). 443 double cms_consumption_rate() const; 444 445 // Returns an estimate of the number of seconds until the cms generation will 446 // fill up, assuming no collection work is done. 447 double time_until_cms_gen_full() const; 448 449 // Returns an estimate of the number of seconds remaining until 450 // the cms generation collection should start. 451 double time_until_cms_start() const; 452 453 // End of higher level statistics. 454 455 // Returns the cms incremental mode duty cycle, as a percentage (0-100). 456 unsigned int icms_duty_cycle() const { return _icms_duty_cycle; } 457 458 // Update the duty cycle and return the new value. 459 unsigned int icms_update_duty_cycle(); 460 461 // Debugging. 462 void print_on(outputStream* st) const PRODUCT_RETURN; 463 void print() const { print_on(gclog_or_tty); } 464 }; 465 466 // A closure related to weak references processing which 467 // we embed in the CMSCollector, since we need to pass 468 // it to the reference processor for secondary filtering 469 // of references based on reachability of referent; 470 // see role of _is_alive_non_header closure in the 471 // ReferenceProcessor class. 472 // For objects in the CMS generation, this closure checks 473 // if the object is "live" (reachable). Used in weak 474 // reference processing. 475 class CMSIsAliveClosure: public BoolObjectClosure { 476 const MemRegion _span; 477 const CMSBitMap* _bit_map; 478 479 friend class CMSCollector; 480 public: 481 CMSIsAliveClosure(MemRegion span, 482 CMSBitMap* bit_map): 483 _span(span), 484 _bit_map(bit_map) { 485 assert(!span.is_empty(), "Empty span could spell trouble"); 486 } 487 488 bool do_object_b(oop obj); 489 }; 490 491 492 // Implements AbstractRefProcTaskExecutor for CMS. 493 class CMSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 494 public: 495 496 CMSRefProcTaskExecutor(CMSCollector& collector) 497 : _collector(collector) 498 { } 499 500 // Executes a task using worker threads. 501 virtual void execute(ProcessTask& task); 502 virtual void execute(EnqueueTask& task); 503 private: 504 CMSCollector& _collector; 505 }; 506 507 508 class CMSCollector: public CHeapObj<mtGC> { 509 friend class VMStructs; 510 friend class ConcurrentMarkSweepThread; 511 friend class ConcurrentMarkSweepGeneration; 512 friend class CompactibleFreeListSpace; 513 friend class CMSParRemarkTask; 514 friend class CMSConcMarkingTask; 515 friend class CMSRefProcTaskProxy; 516 friend class CMSRefProcTaskExecutor; 517 friend class ScanMarkedObjectsAgainCarefullyClosure; // for sampling eden 518 friend class SurvivorSpacePrecleanClosure; // --- ditto ------- 519 friend class PushOrMarkClosure; // to access _restart_addr 520 friend class Par_PushOrMarkClosure; // to access _restart_addr 521 friend class MarkFromRootsClosure; // -- ditto -- 522 // ... and for clearing cards 523 friend class Par_MarkFromRootsClosure; // to access _restart_addr 524 // ... and for clearing cards 525 friend class Par_ConcMarkingClosure; // to access _restart_addr etc. 526 friend class MarkFromRootsVerifyClosure; // to access _restart_addr 527 friend class PushAndMarkVerifyClosure; // -- ditto -- 528 friend class MarkRefsIntoAndScanClosure; // to access _overflow_list 529 friend class PushAndMarkClosure; // -- ditto -- 530 friend class Par_PushAndMarkClosure; // -- ditto -- 531 friend class CMSKeepAliveClosure; // -- ditto -- 532 friend class CMSDrainMarkingStackClosure; // -- ditto -- 533 friend class CMSInnerParMarkAndPushClosure; // -- ditto -- 534 NOT_PRODUCT(friend class ScanMarkedObjectsAgainClosure;) // assertion on _overflow_list 535 friend class ReleaseForegroundGC; // to access _foregroundGCShouldWait 536 friend class VM_CMS_Operation; 537 friend class VM_CMS_Initial_Mark; 538 friend class VM_CMS_Final_Remark; 539 friend class TraceCMSMemoryManagerStats; 540 541 private: 542 jlong _time_of_last_gc; 543 void update_time_of_last_gc(jlong now) { 544 _time_of_last_gc = now; 545 } 546 547 OopTaskQueueSet* _task_queues; 548 549 // Overflow list of grey objects, threaded through mark-word 550 // Manipulated with CAS in the parallel/multi-threaded case. 551 oop _overflow_list; 552 // The following array-pair keeps track of mark words 553 // displaced for accomodating overflow list above. 554 // This code will likely be revisited under RFE#4922830. 555 Stack<oop, mtGC> _preserved_oop_stack; 556 Stack<markOop, mtGC> _preserved_mark_stack; 557 558 int* _hash_seed; 559 560 // In support of multi-threaded concurrent phases 561 YieldingFlexibleWorkGang* _conc_workers; 562 563 // Performance Counters 564 CollectorCounters* _gc_counters; 565 566 // Initialization Errors 567 bool _completed_initialization; 568 569 // In support of ExplicitGCInvokesConcurrent 570 static bool _full_gc_requested; 571 unsigned int _collection_count_start; 572 573 // Should we unload classes this concurrent cycle? 574 bool _should_unload_classes; 575 unsigned int _concurrent_cycles_since_last_unload; 576 unsigned int concurrent_cycles_since_last_unload() const { 577 return _concurrent_cycles_since_last_unload; 578 } 579 // Did we (allow) unload classes in the previous concurrent cycle? 580 bool unloaded_classes_last_cycle() const { 581 return concurrent_cycles_since_last_unload() == 0; 582 } 583 // Root scanning options for perm gen 584 int _roots_scanning_options; 585 int roots_scanning_options() const { return _roots_scanning_options; } 586 void add_root_scanning_option(int o) { _roots_scanning_options |= o; } 587 void remove_root_scanning_option(int o) { _roots_scanning_options &= ~o; } 588 589 // Verification support 590 CMSBitMap _verification_mark_bm; 591 void verify_after_remark_work_1(); 592 void verify_after_remark_work_2(); 593 594 // true if any verification flag is on. 595 bool _verifying; 596 bool verifying() const { return _verifying; } 597 void set_verifying(bool v) { _verifying = v; } 598 599 // Collector policy 600 ConcurrentMarkSweepPolicy* _collector_policy; 601 ConcurrentMarkSweepPolicy* collector_policy() { return _collector_policy; } 602 603 void set_did_compact(bool v); 604 605 // XXX Move these to CMSStats ??? FIX ME !!! 606 elapsedTimer _inter_sweep_timer; // time between sweeps 607 elapsedTimer _intra_sweep_timer; // time _in_ sweeps 608 // padded decaying average estimates of the above 609 AdaptivePaddedAverage _inter_sweep_estimate; 610 AdaptivePaddedAverage _intra_sweep_estimate; 611 612 protected: 613 ConcurrentMarkSweepGeneration* _cmsGen; // old gen (CMS) 614 MemRegion _span; // span covering above two 615 CardTableRS* _ct; // card table 616 617 // CMS marking support structures 618 CMSBitMap _markBitMap; 619 CMSBitMap _modUnionTable; 620 CMSMarkStack _markStack; 621 622 HeapWord* _restart_addr; // in support of marking stack overflow 623 void lower_restart_addr(HeapWord* low); 624 625 // Counters in support of marking stack / work queue overflow handling: 626 // a non-zero value indicates certain types of overflow events during 627 // the current CMS cycle and could lead to stack resizing efforts at 628 // an opportune future time. 629 size_t _ser_pmc_preclean_ovflw; 630 size_t _ser_pmc_remark_ovflw; 631 size_t _par_pmc_remark_ovflw; 632 size_t _ser_kac_preclean_ovflw; 633 size_t _ser_kac_ovflw; 634 size_t _par_kac_ovflw; 635 NOT_PRODUCT(ssize_t _num_par_pushes;) 636 637 // ("Weak") Reference processing support 638 ReferenceProcessor* _ref_processor; 639 CMSIsAliveClosure _is_alive_closure; 640 // keep this textually after _markBitMap and _span; c'tor dependency 641 642 ConcurrentMarkSweepThread* _cmsThread; // the thread doing the work 643 ModUnionClosure _modUnionClosure; 644 ModUnionClosurePar _modUnionClosurePar; 645 646 // CMS abstract state machine 647 // initial_state: Idling 648 // next_state(Idling) = {Marking} 649 // next_state(Marking) = {Precleaning, Sweeping} 650 // next_state(Precleaning) = {AbortablePreclean, FinalMarking} 651 // next_state(AbortablePreclean) = {FinalMarking} 652 // next_state(FinalMarking) = {Sweeping} 653 // next_state(Sweeping) = {Resizing} 654 // next_state(Resizing) = {Resetting} 655 // next_state(Resetting) = {Idling} 656 // The numeric values below are chosen so that: 657 // . _collectorState <= Idling == post-sweep && pre-mark 658 // . _collectorState in (Idling, Sweeping) == {initial,final}marking || 659 // precleaning || abortablePrecleanb 660 public: 661 enum CollectorState { 662 Resizing = 0, 663 Resetting = 1, 664 Idling = 2, 665 InitialMarking = 3, 666 Marking = 4, 667 Precleaning = 5, 668 AbortablePreclean = 6, 669 FinalMarking = 7, 670 Sweeping = 8 671 }; 672 protected: 673 static CollectorState _collectorState; 674 675 // State related to prologue/epilogue invocation for my generations 676 bool _between_prologue_and_epilogue; 677 678 // Signalling/State related to coordination between fore- and backgroud GC 679 // Note: When the baton has been passed from background GC to foreground GC, 680 // _foregroundGCIsActive is true and _foregroundGCShouldWait is false. 681 static bool _foregroundGCIsActive; // true iff foreground collector is active or 682 // wants to go active 683 static bool _foregroundGCShouldWait; // true iff background GC is active and has not 684 // yet passed the baton to the foreground GC 685 686 // Support for CMSScheduleRemark (abortable preclean) 687 bool _abort_preclean; 688 bool _start_sampling; 689 690 int _numYields; 691 size_t _numDirtyCards; 692 size_t _sweep_count; 693 // number of full gc's since the last concurrent gc. 694 uint _full_gcs_since_conc_gc; 695 696 // occupancy used for bootstrapping stats 697 double _bootstrap_occupancy; 698 699 // timer 700 elapsedTimer _timer; 701 702 // Timing, allocation and promotion statistics, used for scheduling. 703 CMSStats _stats; 704 705 // Allocation limits installed in the young gen, used only in 706 // CMSIncrementalMode. When an allocation in the young gen would cross one of 707 // these limits, the cms generation is notified and the cms thread is started 708 // or stopped, respectively. 709 HeapWord* _icms_start_limit; 710 HeapWord* _icms_stop_limit; 711 712 enum CMS_op_type { 713 CMS_op_checkpointRootsInitial, 714 CMS_op_checkpointRootsFinal 715 }; 716 717 void do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause); 718 bool stop_world_and_do(CMS_op_type op); 719 720 OopTaskQueueSet* task_queues() { return _task_queues; } 721 int* hash_seed(int i) { return &_hash_seed[i]; } 722 YieldingFlexibleWorkGang* conc_workers() { return _conc_workers; } 723 724 // Support for parallelizing Eden rescan in CMS remark phase 725 void sample_eden(); // ... sample Eden space top 726 727 private: 728 // Support for parallelizing young gen rescan in CMS remark phase 729 Generation* _young_gen; // the younger gen 730 HeapWord** _top_addr; // ... Top of Eden 731 HeapWord** _end_addr; // ... End of Eden 732 HeapWord** _eden_chunk_array; // ... Eden partitioning array 733 size_t _eden_chunk_index; // ... top (exclusive) of array 734 size_t _eden_chunk_capacity; // ... max entries in array 735 736 // Support for parallelizing survivor space rescan 737 HeapWord** _survivor_chunk_array; 738 size_t _survivor_chunk_index; 739 size_t _survivor_chunk_capacity; 740 size_t* _cursor; 741 ChunkArray* _survivor_plab_array; 742 743 // Support for marking stack overflow handling 744 bool take_from_overflow_list(size_t num, CMSMarkStack* to_stack); 745 bool par_take_from_overflow_list(size_t num, 746 OopTaskQueue* to_work_q, 747 int no_of_gc_threads); 748 void push_on_overflow_list(oop p); 749 void par_push_on_overflow_list(oop p); 750 // the following is, obviously, not, in general, "MT-stable" 751 bool overflow_list_is_empty() const; 752 753 void preserve_mark_if_necessary(oop p); 754 void par_preserve_mark_if_necessary(oop p); 755 void preserve_mark_work(oop p, markOop m); 756 void restore_preserved_marks_if_any(); 757 NOT_PRODUCT(bool no_preserved_marks() const;) 758 // in support of testing overflow code 759 NOT_PRODUCT(int _overflow_counter;) 760 NOT_PRODUCT(bool simulate_overflow();) // sequential 761 NOT_PRODUCT(bool par_simulate_overflow();) // MT version 762 763 // CMS work methods 764 void checkpointRootsInitialWork(bool asynch); // initial checkpoint work 765 766 // a return value of false indicates failure due to stack overflow 767 bool markFromRootsWork(bool asynch); // concurrent marking work 768 769 public: // FIX ME!!! only for testing 770 bool do_marking_st(bool asynch); // single-threaded marking 771 bool do_marking_mt(bool asynch); // multi-threaded marking 772 773 private: 774 775 // concurrent precleaning work 776 size_t preclean_mod_union_table(ConcurrentMarkSweepGeneration* gen, 777 ScanMarkedObjectsAgainCarefullyClosure* cl); 778 size_t preclean_card_table(ConcurrentMarkSweepGeneration* gen, 779 ScanMarkedObjectsAgainCarefullyClosure* cl); 780 // Does precleaning work, returning a quantity indicative of 781 // the amount of "useful work" done. 782 size_t preclean_work(bool clean_refs, bool clean_survivors); 783 void preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock); 784 void abortable_preclean(); // Preclean while looking for possible abort 785 void initialize_sequential_subtasks_for_young_gen_rescan(int i); 786 // Helper function for above; merge-sorts the per-thread plab samples 787 void merge_survivor_plab_arrays(ContiguousSpace* surv, int no_of_gc_threads); 788 // Resets (i.e. clears) the per-thread plab sample vectors 789 void reset_survivor_plab_arrays(); 790 791 // final (second) checkpoint work 792 void checkpointRootsFinalWork(bool asynch, bool clear_all_soft_refs, 793 bool init_mark_was_synchronous); 794 // work routine for parallel version of remark 795 void do_remark_parallel(); 796 // work routine for non-parallel version of remark 797 void do_remark_non_parallel(); 798 // reference processing work routine (during second checkpoint) 799 void refProcessingWork(bool asynch, bool clear_all_soft_refs); 800 801 // concurrent sweeping work 802 void sweepWork(ConcurrentMarkSweepGeneration* gen, bool asynch); 803 804 // (concurrent) resetting of support data structures 805 void reset(bool asynch); 806 807 // Clear _expansion_cause fields of constituent generations 808 void clear_expansion_cause(); 809 810 // An auxilliary method used to record the ends of 811 // used regions of each generation to limit the extent of sweep 812 void save_sweep_limits(); 813 814 // A work method used by foreground collection to determine 815 // what type of collection (compacting or not, continuing or fresh) 816 // it should do. 817 void decide_foreground_collection_type(bool clear_all_soft_refs, 818 bool* should_compact, bool* should_start_over); 819 820 // A work method used by the foreground collector to do 821 // a mark-sweep-compact. 822 void do_compaction_work(bool clear_all_soft_refs); 823 824 // A work method used by the foreground collector to do 825 // a mark-sweep, after taking over from a possibly on-going 826 // concurrent mark-sweep collection. 827 void do_mark_sweep_work(bool clear_all_soft_refs, 828 CollectorState first_state, bool should_start_over); 829 830 // If the backgrould GC is active, acquire control from the background 831 // GC and do the collection. 832 void acquire_control_and_collect(bool full, bool clear_all_soft_refs); 833 834 // For synchronizing passing of control from background to foreground 835 // GC. waitForForegroundGC() is called by the background 836 // collector. It if had to wait for a foreground collection, 837 // it returns true and the background collection should assume 838 // that the collection was finished by the foreground 839 // collector. 840 bool waitForForegroundGC(); 841 842 // Incremental mode triggering: recompute the icms duty cycle and set the 843 // allocation limits in the young gen. 844 void icms_update_allocation_limits(); 845 846 size_t block_size_using_printezis_bits(HeapWord* addr) const; 847 size_t block_size_if_printezis_bits(HeapWord* addr) const; 848 HeapWord* next_card_start_after_block(HeapWord* addr) const; 849 850 void setup_cms_unloading_and_verification_state(); 851 public: 852 CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, 853 CardTableRS* ct, 854 ConcurrentMarkSweepPolicy* cp); 855 ConcurrentMarkSweepThread* cmsThread() { return _cmsThread; } 856 857 ReferenceProcessor* ref_processor() { return _ref_processor; } 858 void ref_processor_init(); 859 860 Mutex* bitMapLock() const { return _markBitMap.lock(); } 861 static CollectorState abstract_state() { return _collectorState; } 862 863 bool should_abort_preclean() const; // Whether preclean should be aborted. 864 size_t get_eden_used() const; 865 size_t get_eden_capacity() const; 866 867 ConcurrentMarkSweepGeneration* cmsGen() { return _cmsGen; } 868 869 // locking checks 870 NOT_PRODUCT(static bool have_cms_token();) 871 872 // XXXPERM bool should_collect(bool full, size_t size, bool tlab); 873 bool shouldConcurrentCollect(); 874 875 void collect(bool full, 876 bool clear_all_soft_refs, 877 size_t size, 878 bool tlab); 879 void collect_in_background(bool clear_all_soft_refs); 880 void collect_in_foreground(bool clear_all_soft_refs); 881 882 // In support of ExplicitGCInvokesConcurrent 883 static void request_full_gc(unsigned int full_gc_count); 884 // Should we unload classes in a particular concurrent cycle? 885 bool should_unload_classes() const { 886 return _should_unload_classes; 887 } 888 void update_should_unload_classes(); 889 890 void direct_allocated(HeapWord* start, size_t size); 891 892 // Object is dead if not marked and current phase is sweeping. 893 bool is_dead_obj(oop obj) const; 894 895 // After a promotion (of "start"), do any necessary marking. 896 // If "par", then it's being done by a parallel GC thread. 897 // The last two args indicate if we need precise marking 898 // and if so the size of the object so it can be dirtied 899 // in its entirety. 900 void promoted(bool par, HeapWord* start, 901 bool is_obj_array, size_t obj_size); 902 903 HeapWord* allocation_limit_reached(Space* space, HeapWord* top, 904 size_t word_size); 905 906 void getFreelistLocks() const; 907 void releaseFreelistLocks() const; 908 bool haveFreelistLocks() const; 909 910 // Adjust size of underlying generation 911 void compute_new_size(); 912 913 // GC prologue and epilogue 914 void gc_prologue(bool full); 915 void gc_epilogue(bool full); 916 917 jlong time_of_last_gc(jlong now) { 918 if (_collectorState <= Idling) { 919 // gc not in progress 920 return _time_of_last_gc; 921 } else { 922 // collection in progress 923 return now; 924 } 925 } 926 927 // Support for parallel remark of survivor space 928 void* get_data_recorder(int thr_num); 929 930 CMSBitMap* markBitMap() { return &_markBitMap; } 931 void directAllocated(HeapWord* start, size_t size); 932 933 // main CMS steps and related support 934 void checkpointRootsInitial(bool asynch); 935 bool markFromRoots(bool asynch); // a return value of false indicates failure 936 // due to stack overflow 937 void preclean(); 938 void checkpointRootsFinal(bool asynch, bool clear_all_soft_refs, 939 bool init_mark_was_synchronous); 940 void sweep(bool asynch); 941 942 // Check that the currently executing thread is the expected 943 // one (foreground collector or background collector). 944 static void check_correct_thread_executing() PRODUCT_RETURN; 945 // XXXPERM void print_statistics() PRODUCT_RETURN; 946 947 bool is_cms_reachable(HeapWord* addr); 948 949 // Performance Counter Support 950 CollectorCounters* counters() { return _gc_counters; } 951 952 // timer stuff 953 void startTimer() { assert(!_timer.is_active(), "Error"); _timer.start(); } 954 void stopTimer() { assert( _timer.is_active(), "Error"); _timer.stop(); } 955 void resetTimer() { assert(!_timer.is_active(), "Error"); _timer.reset(); } 956 double timerValue() { assert(!_timer.is_active(), "Error"); return _timer.seconds(); } 957 958 int yields() { return _numYields; } 959 void resetYields() { _numYields = 0; } 960 void incrementYields() { _numYields++; } 961 void resetNumDirtyCards() { _numDirtyCards = 0; } 962 void incrementNumDirtyCards(size_t num) { _numDirtyCards += num; } 963 size_t numDirtyCards() { return _numDirtyCards; } 964 965 static bool foregroundGCShouldWait() { return _foregroundGCShouldWait; } 966 static void set_foregroundGCShouldWait(bool v) { _foregroundGCShouldWait = v; } 967 static bool foregroundGCIsActive() { return _foregroundGCIsActive; } 968 static void set_foregroundGCIsActive(bool v) { _foregroundGCIsActive = v; } 969 size_t sweep_count() const { return _sweep_count; } 970 void increment_sweep_count() { _sweep_count++; } 971 972 // Timers/stats for gc scheduling and incremental mode pacing. 973 CMSStats& stats() { return _stats; } 974 975 // Convenience methods that check whether CMSIncrementalMode is enabled and 976 // forward to the corresponding methods in ConcurrentMarkSweepThread. 977 static void start_icms(); 978 static void stop_icms(); // Called at the end of the cms cycle. 979 static void disable_icms(); // Called before a foreground collection. 980 static void enable_icms(); // Called after a foreground collection. 981 void icms_wait(); // Called at yield points. 982 983 // Adaptive size policy 984 CMSAdaptiveSizePolicy* size_policy(); 985 CMSGCAdaptivePolicyCounters* gc_adaptive_policy_counters(); 986 987 static void print_on_error(outputStream* st); 988 989 // debugging 990 void verify(); 991 bool verify_after_remark(bool silent = VerifySilently); 992 void verify_ok_to_terminate() const PRODUCT_RETURN; 993 void verify_work_stacks_empty() const PRODUCT_RETURN; 994 void verify_overflow_empty() const PRODUCT_RETURN; 995 996 // convenience methods in support of debugging 997 static const size_t skip_header_HeapWords() PRODUCT_RETURN0; 998 HeapWord* block_start(const void* p) const PRODUCT_RETURN0; 999 1000 // accessors 1001 CMSMarkStack* verification_mark_stack() { return &_markStack; } 1002 CMSBitMap* verification_mark_bm() { return &_verification_mark_bm; } 1003 1004 // Initialization errors 1005 bool completed_initialization() { return _completed_initialization; } 1006 }; 1007 1008 class CMSExpansionCause : public AllStatic { 1009 public: 1010 enum Cause { 1011 _no_expansion, 1012 _satisfy_free_ratio, 1013 _satisfy_promotion, 1014 _satisfy_allocation, 1015 _allocate_par_lab, 1016 _allocate_par_spooling_space, 1017 _adaptive_size_policy 1018 }; 1019 // Return a string describing the cause of the expansion. 1020 static const char* to_string(CMSExpansionCause::Cause cause); 1021 }; 1022 1023 class ConcurrentMarkSweepGeneration: public CardGeneration { 1024 friend class VMStructs; 1025 friend class ConcurrentMarkSweepThread; 1026 friend class ConcurrentMarkSweep; 1027 friend class CMSCollector; 1028 protected: 1029 static CMSCollector* _collector; // the collector that collects us 1030 CompactibleFreeListSpace* _cmsSpace; // underlying space (only one for now) 1031 1032 // Performance Counters 1033 GenerationCounters* _gen_counters; 1034 GSpaceCounters* _space_counters; 1035 1036 // Words directly allocated, used by CMSStats. 1037 size_t _direct_allocated_words; 1038 1039 // Non-product stat counters 1040 NOT_PRODUCT( 1041 size_t _numObjectsPromoted; 1042 size_t _numWordsPromoted; 1043 size_t _numObjectsAllocated; 1044 size_t _numWordsAllocated; 1045 ) 1046 1047 // Used for sizing decisions 1048 bool _incremental_collection_failed; 1049 bool incremental_collection_failed() { 1050 return _incremental_collection_failed; 1051 } 1052 void set_incremental_collection_failed() { 1053 _incremental_collection_failed = true; 1054 } 1055 void clear_incremental_collection_failed() { 1056 _incremental_collection_failed = false; 1057 } 1058 1059 // accessors 1060 void set_expansion_cause(CMSExpansionCause::Cause v) { _expansion_cause = v;} 1061 CMSExpansionCause::Cause expansion_cause() const { return _expansion_cause; } 1062 1063 private: 1064 // For parallel young-gen GC support. 1065 CMSParGCThreadState** _par_gc_thread_states; 1066 1067 // Reason generation was expanded 1068 CMSExpansionCause::Cause _expansion_cause; 1069 1070 // In support of MinChunkSize being larger than min object size 1071 const double _dilatation_factor; 1072 1073 enum CollectionTypes { 1074 Concurrent_collection_type = 0, 1075 MS_foreground_collection_type = 1, 1076 MSC_foreground_collection_type = 2, 1077 Unknown_collection_type = 3 1078 }; 1079 1080 CollectionTypes _debug_collection_type; 1081 1082 // True if a compactiing collection was done. 1083 bool _did_compact; 1084 bool did_compact() { return _did_compact; } 1085 1086 // Fraction of current occupancy at which to start a CMS collection which 1087 // will collect this generation (at least). 1088 double _initiating_occupancy; 1089 1090 protected: 1091 // Shrink generation by specified size (returns false if unable to shrink) 1092 void shrink_free_list_by(size_t bytes); 1093 1094 // Update statistics for GC 1095 virtual void update_gc_stats(int level, bool full); 1096 1097 // Maximum available space in the generation (including uncommitted) 1098 // space. 1099 size_t max_available() const; 1100 1101 // getter and initializer for _initiating_occupancy field. 1102 double initiating_occupancy() const { return _initiating_occupancy; } 1103 void init_initiating_occupancy(intx io, uintx tr); 1104 1105 public: 1106 ConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, 1107 int level, CardTableRS* ct, 1108 bool use_adaptive_freelists, 1109 FreeBlockDictionary<FreeChunk>::DictionaryChoice); 1110 1111 // Accessors 1112 CMSCollector* collector() const { return _collector; } 1113 static void set_collector(CMSCollector* collector) { 1114 assert(_collector == NULL, "already set"); 1115 _collector = collector; 1116 } 1117 CompactibleFreeListSpace* cmsSpace() const { return _cmsSpace; } 1118 1119 Mutex* freelistLock() const; 1120 1121 virtual Generation::Name kind() { return Generation::ConcurrentMarkSweep; } 1122 1123 // Adaptive size policy 1124 CMSAdaptiveSizePolicy* size_policy(); 1125 1126 void set_did_compact(bool v) { _did_compact = v; } 1127 1128 bool refs_discovery_is_atomic() const { return false; } 1129 bool refs_discovery_is_mt() const { 1130 // Note: CMS does MT-discovery during the parallel-remark 1131 // phases. Use ReferenceProcessorMTMutator to make refs 1132 // discovery MT-safe during such phases or other parallel 1133 // discovery phases in the future. This may all go away 1134 // if/when we decide that refs discovery is sufficiently 1135 // rare that the cost of the CAS's involved is in the 1136 // noise. That's a measurement that should be done, and 1137 // the code simplified if that turns out to be the case. 1138 return ConcGCThreads > 1; 1139 } 1140 1141 // Override 1142 virtual void ref_processor_init(); 1143 1144 // Grow generation by specified size (returns false if unable to grow) 1145 bool grow_by(size_t bytes); 1146 // Grow generation to reserved size. 1147 bool grow_to_reserved(); 1148 1149 void clear_expansion_cause() { _expansion_cause = CMSExpansionCause::_no_expansion; } 1150 1151 // Space enquiries 1152 size_t capacity() const; 1153 size_t used() const; 1154 size_t free() const; 1155 double occupancy() const { return ((double)used())/((double)capacity()); } 1156 size_t contiguous_available() const; 1157 size_t unsafe_max_alloc_nogc() const; 1158 1159 // over-rides 1160 MemRegion used_region() const; 1161 MemRegion used_region_at_save_marks() const; 1162 1163 // Does a "full" (forced) collection invoked on this generation collect 1164 // all younger generations as well? Note that the second conjunct is a 1165 // hack to allow the collection of the younger gen first if the flag is 1166 // set. This is better than using th policy's should_collect_gen0_first() 1167 // since that causes us to do an extra unnecessary pair of restart-&-stop-world. 1168 virtual bool full_collects_younger_generations() const { 1169 return UseCMSCompactAtFullCollection && !CollectGen0First; 1170 } 1171 1172 void space_iterate(SpaceClosure* blk, bool usedOnly = false); 1173 1174 // Support for compaction 1175 CompactibleSpace* first_compaction_space() const; 1176 // Adjust quantites in the generation affected by 1177 // the compaction. 1178 void reset_after_compaction(); 1179 1180 // Allocation support 1181 HeapWord* allocate(size_t size, bool tlab); 1182 HeapWord* have_lock_and_allocate(size_t size, bool tlab); 1183 oop promote(oop obj, size_t obj_size); 1184 HeapWord* par_allocate(size_t size, bool tlab) { 1185 return allocate(size, tlab); 1186 } 1187 1188 // Incremental mode triggering. 1189 HeapWord* allocation_limit_reached(Space* space, HeapWord* top, 1190 size_t word_size); 1191 1192 // Used by CMSStats to track direct allocation. The value is sampled and 1193 // reset after each young gen collection. 1194 size_t direct_allocated_words() const { return _direct_allocated_words; } 1195 void reset_direct_allocated_words() { _direct_allocated_words = 0; } 1196 1197 // Overrides for parallel promotion. 1198 virtual oop par_promote(int thread_num, 1199 oop obj, markOop m, size_t word_sz); 1200 // This one should not be called for CMS. 1201 virtual void par_promote_alloc_undo(int thread_num, 1202 HeapWord* obj, size_t word_sz); 1203 virtual void par_promote_alloc_done(int thread_num); 1204 virtual void par_oop_since_save_marks_iterate_done(int thread_num); 1205 1206 virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes) const; 1207 1208 // Inform this (non-young) generation that a promotion failure was 1209 // encountered during a collection of a younger generation that 1210 // promotes into this generation. 1211 virtual void promotion_failure_occurred(); 1212 1213 bool should_collect(bool full, size_t size, bool tlab); 1214 virtual bool should_concurrent_collect() const; 1215 virtual bool is_too_full() const; 1216 void collect(bool full, 1217 bool clear_all_soft_refs, 1218 size_t size, 1219 bool tlab); 1220 1221 HeapWord* expand_and_allocate(size_t word_size, 1222 bool tlab, 1223 bool parallel = false); 1224 1225 // GC prologue and epilogue 1226 void gc_prologue(bool full); 1227 void gc_prologue_work(bool full, bool registerClosure, 1228 ModUnionClosure* modUnionClosure); 1229 void gc_epilogue(bool full); 1230 void gc_epilogue_work(bool full); 1231 1232 // Time since last GC of this generation 1233 jlong time_of_last_gc(jlong now) { 1234 return collector()->time_of_last_gc(now); 1235 } 1236 void update_time_of_last_gc(jlong now) { 1237 collector()-> update_time_of_last_gc(now); 1238 } 1239 1240 // Allocation failure 1241 void expand(size_t bytes, size_t expand_bytes, 1242 CMSExpansionCause::Cause cause); 1243 virtual bool expand(size_t bytes, size_t expand_bytes); 1244 void shrink(size_t bytes); 1245 void shrink_by(size_t bytes); 1246 HeapWord* expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz); 1247 bool expand_and_ensure_spooling_space(PromotionInfo* promo); 1248 1249 // Iteration support and related enquiries 1250 void save_marks(); 1251 bool no_allocs_since_save_marks(); 1252 void younger_refs_iterate(OopsInGenClosure* cl); 1253 1254 // Iteration support specific to CMS generations 1255 void save_sweep_limit(); 1256 1257 // More iteration support 1258 virtual void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1259 virtual void oop_iterate(ExtendedOopClosure* cl); 1260 virtual void safe_object_iterate(ObjectClosure* cl); 1261 virtual void object_iterate(ObjectClosure* cl); 1262 1263 // Need to declare the full complement of closures, whether we'll 1264 // override them or not, or get message from the compiler: 1265 // oop_since_save_marks_iterate_nv hides virtual function... 1266 #define CMS_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 1267 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); 1268 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DECL) 1269 1270 // Smart allocation XXX -- move to CFLSpace? 1271 void setNearLargestChunk(); 1272 bool isNearLargestChunk(HeapWord* addr); 1273 1274 // Get the chunk at the end of the space. Delagates to 1275 // the space. 1276 FreeChunk* find_chunk_at_end(); 1277 1278 void post_compact(); 1279 1280 // Debugging 1281 void prepare_for_verify(); 1282 void verify(); 1283 void print_statistics() PRODUCT_RETURN; 1284 1285 // Performance Counters support 1286 virtual void update_counters(); 1287 virtual void update_counters(size_t used); 1288 void initialize_performance_counters(); 1289 CollectorCounters* counters() { return collector()->counters(); } 1290 1291 // Support for parallel remark of survivor space 1292 void* get_data_recorder(int thr_num) { 1293 //Delegate to collector 1294 return collector()->get_data_recorder(thr_num); 1295 } 1296 1297 // Printing 1298 const char* name() const; 1299 virtual const char* short_name() const { return "CMS"; } 1300 void print() const; 1301 void printOccupancy(const char* s); 1302 bool must_be_youngest() const { return false; } 1303 bool must_be_oldest() const { return true; } 1304 1305 // Resize the generation after a compacting GC. The 1306 // generation can be treated as a contiguous space 1307 // after the compaction. 1308 virtual void compute_new_size(); 1309 // Resize the generation after a non-compacting 1310 // collection. 1311 void compute_new_size_free_list(); 1312 1313 CollectionTypes debug_collection_type() { return _debug_collection_type; } 1314 void rotate_debug_collection_type(); 1315 }; 1316 1317 class ASConcurrentMarkSweepGeneration : public ConcurrentMarkSweepGeneration { 1318 1319 // Return the size policy from the heap's collector 1320 // policy casted to CMSAdaptiveSizePolicy*. 1321 CMSAdaptiveSizePolicy* cms_size_policy() const; 1322 1323 // Resize the generation based on the adaptive size 1324 // policy. 1325 void resize(size_t cur_promo, size_t desired_promo); 1326 1327 // Return the GC counters from the collector policy 1328 CMSGCAdaptivePolicyCounters* gc_adaptive_policy_counters(); 1329 1330 virtual void shrink_by(size_t bytes); 1331 1332 public: 1333 ASConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, 1334 int level, CardTableRS* ct, 1335 bool use_adaptive_freelists, 1336 FreeBlockDictionary<FreeChunk>::DictionaryChoice 1337 dictionaryChoice) : 1338 ConcurrentMarkSweepGeneration(rs, initial_byte_size, level, ct, 1339 use_adaptive_freelists, dictionaryChoice) {} 1340 1341 virtual const char* short_name() const { return "ASCMS"; } 1342 virtual Generation::Name kind() { return Generation::ASConcurrentMarkSweep; } 1343 1344 virtual void update_counters(); 1345 virtual void update_counters(size_t used); 1346 }; 1347 1348 // 1349 // Closures of various sorts used by CMS to accomplish its work 1350 // 1351 1352 // This closure is used to check that a certain set of oops is empty. 1353 class FalseClosure: public OopClosure { 1354 public: 1355 void do_oop(oop* p) { guarantee(false, "Should be an empty set"); } 1356 void do_oop(narrowOop* p) { guarantee(false, "Should be an empty set"); } 1357 }; 1358 1359 // This closure is used to do concurrent marking from the roots 1360 // following the first checkpoint. 1361 class MarkFromRootsClosure: public BitMapClosure { 1362 CMSCollector* _collector; 1363 MemRegion _span; 1364 CMSBitMap* _bitMap; 1365 CMSBitMap* _mut; 1366 CMSMarkStack* _markStack; 1367 bool _yield; 1368 int _skipBits; 1369 HeapWord* _finger; 1370 HeapWord* _threshold; 1371 DEBUG_ONLY(bool _verifying;) 1372 1373 public: 1374 MarkFromRootsClosure(CMSCollector* collector, MemRegion span, 1375 CMSBitMap* bitMap, 1376 CMSMarkStack* markStack, 1377 bool should_yield, bool verifying = false); 1378 bool do_bit(size_t offset); 1379 void reset(HeapWord* addr); 1380 inline void do_yield_check(); 1381 1382 private: 1383 void scanOopsInOop(HeapWord* ptr); 1384 void do_yield_work(); 1385 }; 1386 1387 // This closure is used to do concurrent multi-threaded 1388 // marking from the roots following the first checkpoint. 1389 // XXX This should really be a subclass of The serial version 1390 // above, but i have not had the time to refactor things cleanly. 1391 // That willbe done for Dolphin. 1392 class Par_MarkFromRootsClosure: public BitMapClosure { 1393 CMSCollector* _collector; 1394 MemRegion _whole_span; 1395 MemRegion _span; 1396 CMSBitMap* _bit_map; 1397 CMSBitMap* _mut; 1398 OopTaskQueue* _work_queue; 1399 CMSMarkStack* _overflow_stack; 1400 bool _yield; 1401 int _skip_bits; 1402 HeapWord* _finger; 1403 HeapWord* _threshold; 1404 CMSConcMarkingTask* _task; 1405 public: 1406 Par_MarkFromRootsClosure(CMSConcMarkingTask* task, CMSCollector* collector, 1407 MemRegion span, 1408 CMSBitMap* bit_map, 1409 OopTaskQueue* work_queue, 1410 CMSMarkStack* overflow_stack, 1411 bool should_yield); 1412 bool do_bit(size_t offset); 1413 inline void do_yield_check(); 1414 1415 private: 1416 void scan_oops_in_oop(HeapWord* ptr); 1417 void do_yield_work(); 1418 bool get_work_from_overflow_stack(); 1419 }; 1420 1421 // The following closures are used to do certain kinds of verification of 1422 // CMS marking. 1423 class PushAndMarkVerifyClosure: public CMSOopClosure { 1424 CMSCollector* _collector; 1425 MemRegion _span; 1426 CMSBitMap* _verification_bm; 1427 CMSBitMap* _cms_bm; 1428 CMSMarkStack* _mark_stack; 1429 protected: 1430 void do_oop(oop p); 1431 template <class T> inline void do_oop_work(T *p) { 1432 oop obj = oopDesc::load_decode_heap_oop(p); 1433 do_oop(obj); 1434 } 1435 public: 1436 PushAndMarkVerifyClosure(CMSCollector* cms_collector, 1437 MemRegion span, 1438 CMSBitMap* verification_bm, 1439 CMSBitMap* cms_bm, 1440 CMSMarkStack* mark_stack); 1441 void do_oop(oop* p); 1442 void do_oop(narrowOop* p); 1443 1444 // Deal with a stack overflow condition 1445 void handle_stack_overflow(HeapWord* lost); 1446 }; 1447 1448 class MarkFromRootsVerifyClosure: public BitMapClosure { 1449 CMSCollector* _collector; 1450 MemRegion _span; 1451 CMSBitMap* _verification_bm; 1452 CMSBitMap* _cms_bm; 1453 CMSMarkStack* _mark_stack; 1454 HeapWord* _finger; 1455 PushAndMarkVerifyClosure _pam_verify_closure; 1456 public: 1457 MarkFromRootsVerifyClosure(CMSCollector* collector, MemRegion span, 1458 CMSBitMap* verification_bm, 1459 CMSBitMap* cms_bm, 1460 CMSMarkStack* mark_stack); 1461 bool do_bit(size_t offset); 1462 void reset(HeapWord* addr); 1463 }; 1464 1465 1466 // This closure is used to check that a certain set of bits is 1467 // "empty" (i.e. the bit vector doesn't have any 1-bits). 1468 class FalseBitMapClosure: public BitMapClosure { 1469 public: 1470 bool do_bit(size_t offset) { 1471 guarantee(false, "Should not have a 1 bit"); 1472 return true; 1473 } 1474 }; 1475 1476 // This closure is used during the second checkpointing phase 1477 // to rescan the marked objects on the dirty cards in the mod 1478 // union table and the card table proper. It's invoked via 1479 // MarkFromDirtyCardsClosure below. It uses either 1480 // [Par_]MarkRefsIntoAndScanClosure (Par_ in the parallel case) 1481 // declared in genOopClosures.hpp to accomplish some of its work. 1482 // In the parallel case the bitMap is shared, so access to 1483 // it needs to be suitably synchronized for updates by embedded 1484 // closures that update it; however, this closure itself only 1485 // reads the bit_map and because it is idempotent, is immune to 1486 // reading stale values. 1487 class ScanMarkedObjectsAgainClosure: public UpwardsObjectClosure { 1488 #ifdef ASSERT 1489 CMSCollector* _collector; 1490 MemRegion _span; 1491 union { 1492 CMSMarkStack* _mark_stack; 1493 OopTaskQueue* _work_queue; 1494 }; 1495 #endif // ASSERT 1496 bool _parallel; 1497 CMSBitMap* _bit_map; 1498 union { 1499 MarkRefsIntoAndScanClosure* _scan_closure; 1500 Par_MarkRefsIntoAndScanClosure* _par_scan_closure; 1501 }; 1502 1503 public: 1504 ScanMarkedObjectsAgainClosure(CMSCollector* collector, 1505 MemRegion span, 1506 ReferenceProcessor* rp, 1507 CMSBitMap* bit_map, 1508 CMSMarkStack* mark_stack, 1509 MarkRefsIntoAndScanClosure* cl): 1510 #ifdef ASSERT 1511 _collector(collector), 1512 _span(span), 1513 _mark_stack(mark_stack), 1514 #endif // ASSERT 1515 _parallel(false), 1516 _bit_map(bit_map), 1517 _scan_closure(cl) { } 1518 1519 ScanMarkedObjectsAgainClosure(CMSCollector* collector, 1520 MemRegion span, 1521 ReferenceProcessor* rp, 1522 CMSBitMap* bit_map, 1523 OopTaskQueue* work_queue, 1524 Par_MarkRefsIntoAndScanClosure* cl): 1525 #ifdef ASSERT 1526 _collector(collector), 1527 _span(span), 1528 _work_queue(work_queue), 1529 #endif // ASSERT 1530 _parallel(true), 1531 _bit_map(bit_map), 1532 _par_scan_closure(cl) { } 1533 1534 bool do_object_b(oop obj) { 1535 guarantee(false, "Call do_object_b(oop, MemRegion) form instead"); 1536 return false; 1537 } 1538 bool do_object_bm(oop p, MemRegion mr); 1539 }; 1540 1541 // This closure is used during the second checkpointing phase 1542 // to rescan the marked objects on the dirty cards in the mod 1543 // union table and the card table proper. It invokes 1544 // ScanMarkedObjectsAgainClosure above to accomplish much of its work. 1545 // In the parallel case, the bit map is shared and requires 1546 // synchronized access. 1547 class MarkFromDirtyCardsClosure: public MemRegionClosure { 1548 CompactibleFreeListSpace* _space; 1549 ScanMarkedObjectsAgainClosure _scan_cl; 1550 size_t _num_dirty_cards; 1551 1552 public: 1553 MarkFromDirtyCardsClosure(CMSCollector* collector, 1554 MemRegion span, 1555 CompactibleFreeListSpace* space, 1556 CMSBitMap* bit_map, 1557 CMSMarkStack* mark_stack, 1558 MarkRefsIntoAndScanClosure* cl): 1559 _space(space), 1560 _num_dirty_cards(0), 1561 _scan_cl(collector, span, collector->ref_processor(), bit_map, 1562 mark_stack, cl) { } 1563 1564 MarkFromDirtyCardsClosure(CMSCollector* collector, 1565 MemRegion span, 1566 CompactibleFreeListSpace* space, 1567 CMSBitMap* bit_map, 1568 OopTaskQueue* work_queue, 1569 Par_MarkRefsIntoAndScanClosure* cl): 1570 _space(space), 1571 _num_dirty_cards(0), 1572 _scan_cl(collector, span, collector->ref_processor(), bit_map, 1573 work_queue, cl) { } 1574 1575 void do_MemRegion(MemRegion mr); 1576 void set_space(CompactibleFreeListSpace* space) { _space = space; } 1577 size_t num_dirty_cards() { return _num_dirty_cards; } 1578 }; 1579 1580 // This closure is used in the non-product build to check 1581 // that there are no MemRegions with a certain property. 1582 class FalseMemRegionClosure: public MemRegionClosure { 1583 void do_MemRegion(MemRegion mr) { 1584 guarantee(!mr.is_empty(), "Shouldn't be empty"); 1585 guarantee(false, "Should never be here"); 1586 } 1587 }; 1588 1589 // This closure is used during the precleaning phase 1590 // to "carefully" rescan marked objects on dirty cards. 1591 // It uses MarkRefsIntoAndScanClosure declared in genOopClosures.hpp 1592 // to accomplish some of its work. 1593 class ScanMarkedObjectsAgainCarefullyClosure: public ObjectClosureCareful { 1594 CMSCollector* _collector; 1595 MemRegion _span; 1596 bool _yield; 1597 Mutex* _freelistLock; 1598 CMSBitMap* _bitMap; 1599 CMSMarkStack* _markStack; 1600 MarkRefsIntoAndScanClosure* _scanningClosure; 1601 1602 public: 1603 ScanMarkedObjectsAgainCarefullyClosure(CMSCollector* collector, 1604 MemRegion span, 1605 CMSBitMap* bitMap, 1606 CMSMarkStack* markStack, 1607 MarkRefsIntoAndScanClosure* cl, 1608 bool should_yield): 1609 _collector(collector), 1610 _span(span), 1611 _yield(should_yield), 1612 _bitMap(bitMap), 1613 _markStack(markStack), 1614 _scanningClosure(cl) { 1615 } 1616 1617 void do_object(oop p) { 1618 guarantee(false, "call do_object_careful instead"); 1619 } 1620 1621 size_t do_object_careful(oop p) { 1622 guarantee(false, "Unexpected caller"); 1623 return 0; 1624 } 1625 1626 size_t do_object_careful_m(oop p, MemRegion mr); 1627 1628 void setFreelistLock(Mutex* m) { 1629 _freelistLock = m; 1630 _scanningClosure->set_freelistLock(m); 1631 } 1632 1633 private: 1634 inline bool do_yield_check(); 1635 1636 void do_yield_work(); 1637 }; 1638 1639 class SurvivorSpacePrecleanClosure: public ObjectClosureCareful { 1640 CMSCollector* _collector; 1641 MemRegion _span; 1642 bool _yield; 1643 CMSBitMap* _bit_map; 1644 CMSMarkStack* _mark_stack; 1645 PushAndMarkClosure* _scanning_closure; 1646 unsigned int _before_count; 1647 1648 public: 1649 SurvivorSpacePrecleanClosure(CMSCollector* collector, 1650 MemRegion span, 1651 CMSBitMap* bit_map, 1652 CMSMarkStack* mark_stack, 1653 PushAndMarkClosure* cl, 1654 unsigned int before_count, 1655 bool should_yield): 1656 _collector(collector), 1657 _span(span), 1658 _yield(should_yield), 1659 _bit_map(bit_map), 1660 _mark_stack(mark_stack), 1661 _scanning_closure(cl), 1662 _before_count(before_count) 1663 { } 1664 1665 void do_object(oop p) { 1666 guarantee(false, "call do_object_careful instead"); 1667 } 1668 1669 size_t do_object_careful(oop p); 1670 1671 size_t do_object_careful_m(oop p, MemRegion mr) { 1672 guarantee(false, "Unexpected caller"); 1673 return 0; 1674 } 1675 1676 private: 1677 inline void do_yield_check(); 1678 void do_yield_work(); 1679 }; 1680 1681 // This closure is used to accomplish the sweeping work 1682 // after the second checkpoint but before the concurrent reset 1683 // phase. 1684 // 1685 // Terminology 1686 // left hand chunk (LHC) - block of one or more chunks currently being 1687 // coalesced. The LHC is available for coalescing with a new chunk. 1688 // right hand chunk (RHC) - block that is currently being swept that is 1689 // free or garbage that can be coalesced with the LHC. 1690 // _inFreeRange is true if there is currently a LHC 1691 // _lastFreeRangeCoalesced is true if the LHC consists of more than one chunk. 1692 // _freeRangeInFreeLists is true if the LHC is in the free lists. 1693 // _freeFinger is the address of the current LHC 1694 class SweepClosure: public BlkClosureCareful { 1695 CMSCollector* _collector; // collector doing the work 1696 ConcurrentMarkSweepGeneration* _g; // Generation being swept 1697 CompactibleFreeListSpace* _sp; // Space being swept 1698 HeapWord* _limit;// the address at or above which the sweep should stop 1699 // because we do not expect newly garbage blocks 1700 // eligible for sweeping past that address. 1701 Mutex* _freelistLock; // Free list lock (in space) 1702 CMSBitMap* _bitMap; // Marking bit map (in 1703 // generation) 1704 bool _inFreeRange; // Indicates if we are in the 1705 // midst of a free run 1706 bool _freeRangeInFreeLists; 1707 // Often, we have just found 1708 // a free chunk and started 1709 // a new free range; we do not 1710 // eagerly remove this chunk from 1711 // the free lists unless there is 1712 // a possibility of coalescing. 1713 // When true, this flag indicates 1714 // that the _freeFinger below 1715 // points to a potentially free chunk 1716 // that may still be in the free lists 1717 bool _lastFreeRangeCoalesced; 1718 // free range contains chunks 1719 // coalesced 1720 bool _yield; 1721 // Whether sweeping should be 1722 // done with yields. For instance 1723 // when done by the foreground 1724 // collector we shouldn't yield. 1725 HeapWord* _freeFinger; // When _inFreeRange is set, the 1726 // pointer to the "left hand 1727 // chunk" 1728 size_t _freeRangeSize; 1729 // When _inFreeRange is set, this 1730 // indicates the accumulated size 1731 // of the "left hand chunk" 1732 NOT_PRODUCT( 1733 size_t _numObjectsFreed; 1734 size_t _numWordsFreed; 1735 size_t _numObjectsLive; 1736 size_t _numWordsLive; 1737 size_t _numObjectsAlreadyFree; 1738 size_t _numWordsAlreadyFree; 1739 FreeChunk* _last_fc; 1740 ) 1741 private: 1742 // Code that is common to a free chunk or garbage when 1743 // encountered during sweeping. 1744 void do_post_free_or_garbage_chunk(FreeChunk *fc, size_t chunkSize); 1745 // Process a free chunk during sweeping. 1746 void do_already_free_chunk(FreeChunk *fc); 1747 // Work method called when processing an already free or a 1748 // freshly garbage chunk to do a lookahead and possibly a 1749 // premptive flush if crossing over _limit. 1750 void lookahead_and_flush(FreeChunk* fc, size_t chunkSize); 1751 // Process a garbage chunk during sweeping. 1752 size_t do_garbage_chunk(FreeChunk *fc); 1753 // Process a live chunk during sweeping. 1754 size_t do_live_chunk(FreeChunk* fc); 1755 1756 // Accessors. 1757 HeapWord* freeFinger() const { return _freeFinger; } 1758 void set_freeFinger(HeapWord* v) { _freeFinger = v; } 1759 bool inFreeRange() const { return _inFreeRange; } 1760 void set_inFreeRange(bool v) { _inFreeRange = v; } 1761 bool lastFreeRangeCoalesced() const { return _lastFreeRangeCoalesced; } 1762 void set_lastFreeRangeCoalesced(bool v) { _lastFreeRangeCoalesced = v; } 1763 bool freeRangeInFreeLists() const { return _freeRangeInFreeLists; } 1764 void set_freeRangeInFreeLists(bool v) { _freeRangeInFreeLists = v; } 1765 1766 // Initialize a free range. 1767 void initialize_free_range(HeapWord* freeFinger, bool freeRangeInFreeLists); 1768 // Return this chunk to the free lists. 1769 void flush_cur_free_chunk(HeapWord* chunk, size_t size); 1770 1771 // Check if we should yield and do so when necessary. 1772 inline void do_yield_check(HeapWord* addr); 1773 1774 // Yield 1775 void do_yield_work(HeapWord* addr); 1776 1777 // Debugging/Printing 1778 void print_free_block_coalesced(FreeChunk* fc) const; 1779 1780 public: 1781 SweepClosure(CMSCollector* collector, ConcurrentMarkSweepGeneration* g, 1782 CMSBitMap* bitMap, bool should_yield); 1783 ~SweepClosure() PRODUCT_RETURN; 1784 1785 size_t do_blk_careful(HeapWord* addr); 1786 void print() const { print_on(tty); } 1787 void print_on(outputStream *st) const; 1788 }; 1789 1790 // Closures related to weak references processing 1791 1792 // During CMS' weak reference processing, this is a 1793 // work-routine/closure used to complete transitive 1794 // marking of objects as live after a certain point 1795 // in which an initial set has been completely accumulated. 1796 // This closure is currently used both during the final 1797 // remark stop-world phase, as well as during the concurrent 1798 // precleaning of the discovered reference lists. 1799 class CMSDrainMarkingStackClosure: public VoidClosure { 1800 CMSCollector* _collector; 1801 MemRegion _span; 1802 CMSMarkStack* _mark_stack; 1803 CMSBitMap* _bit_map; 1804 CMSKeepAliveClosure* _keep_alive; 1805 bool _concurrent_precleaning; 1806 public: 1807 CMSDrainMarkingStackClosure(CMSCollector* collector, MemRegion span, 1808 CMSBitMap* bit_map, CMSMarkStack* mark_stack, 1809 CMSKeepAliveClosure* keep_alive, 1810 bool cpc): 1811 _collector(collector), 1812 _span(span), 1813 _bit_map(bit_map), 1814 _mark_stack(mark_stack), 1815 _keep_alive(keep_alive), 1816 _concurrent_precleaning(cpc) { 1817 assert(_concurrent_precleaning == _keep_alive->concurrent_precleaning(), 1818 "Mismatch"); 1819 } 1820 1821 void do_void(); 1822 }; 1823 1824 // A parallel version of CMSDrainMarkingStackClosure above. 1825 class CMSParDrainMarkingStackClosure: public VoidClosure { 1826 CMSCollector* _collector; 1827 MemRegion _span; 1828 OopTaskQueue* _work_queue; 1829 CMSBitMap* _bit_map; 1830 CMSInnerParMarkAndPushClosure _mark_and_push; 1831 1832 public: 1833 CMSParDrainMarkingStackClosure(CMSCollector* collector, 1834 MemRegion span, CMSBitMap* bit_map, 1835 OopTaskQueue* work_queue): 1836 _collector(collector), 1837 _span(span), 1838 _bit_map(bit_map), 1839 _work_queue(work_queue), 1840 _mark_and_push(collector, span, bit_map, work_queue) { } 1841 1842 public: 1843 void trim_queue(uint max); 1844 void do_void(); 1845 }; 1846 1847 // Allow yielding or short-circuiting of reference list 1848 // prelceaning work. 1849 class CMSPrecleanRefsYieldClosure: public YieldClosure { 1850 CMSCollector* _collector; 1851 void do_yield_work(); 1852 public: 1853 CMSPrecleanRefsYieldClosure(CMSCollector* collector): 1854 _collector(collector) {} 1855 virtual bool should_return(); 1856 }; 1857 1858 1859 // Convenience class that locks free list locks for given CMS collector 1860 class FreelistLocker: public StackObj { 1861 private: 1862 CMSCollector* _collector; 1863 public: 1864 FreelistLocker(CMSCollector* collector): 1865 _collector(collector) { 1866 _collector->getFreelistLocks(); 1867 } 1868 1869 ~FreelistLocker() { 1870 _collector->releaseFreelistLocks(); 1871 } 1872 }; 1873 1874 // Mark all dead objects in a given space. 1875 class MarkDeadObjectsClosure: public BlkClosure { 1876 const CMSCollector* _collector; 1877 const CompactibleFreeListSpace* _sp; 1878 CMSBitMap* _live_bit_map; 1879 CMSBitMap* _dead_bit_map; 1880 public: 1881 MarkDeadObjectsClosure(const CMSCollector* collector, 1882 const CompactibleFreeListSpace* sp, 1883 CMSBitMap *live_bit_map, 1884 CMSBitMap *dead_bit_map) : 1885 _collector(collector), 1886 _sp(sp), 1887 _live_bit_map(live_bit_map), 1888 _dead_bit_map(dead_bit_map) {} 1889 size_t do_blk(HeapWord* addr); 1890 }; 1891 1892 class TraceCMSMemoryManagerStats : public TraceMemoryManagerStats { 1893 1894 public: 1895 TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause); 1896 }; 1897 1898 1899 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CONCURRENTMARKSWEEPGENERATION_HPP