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 void do_object(oop obj) { 489 assert(false, "not to be invoked"); 490 } 491 492 bool do_object_b(oop obj); 493 }; 494 495 496 // Implements AbstractRefProcTaskExecutor for CMS. 497 class CMSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 498 public: 499 500 CMSRefProcTaskExecutor(CMSCollector& collector) 501 : _collector(collector) 502 { } 503 504 // Executes a task using worker threads. 505 virtual void execute(ProcessTask& task); 506 virtual void execute(EnqueueTask& task); 507 private: 508 CMSCollector& _collector; 509 }; 510 511 512 class CMSCollector: public CHeapObj<mtGC> { 513 friend class VMStructs; 514 friend class ConcurrentMarkSweepThread; 515 friend class ConcurrentMarkSweepGeneration; 516 friend class CompactibleFreeListSpace; 517 friend class CMSParRemarkTask; 518 friend class CMSConcMarkingTask; 519 friend class CMSRefProcTaskProxy; 520 friend class CMSRefProcTaskExecutor; 521 friend class ScanMarkedObjectsAgainCarefullyClosure; // for sampling eden 522 friend class SurvivorSpacePrecleanClosure; // --- ditto ------- 523 friend class PushOrMarkClosure; // to access _restart_addr 524 friend class Par_PushOrMarkClosure; // to access _restart_addr 525 friend class MarkFromRootsClosure; // -- ditto -- 526 // ... and for clearing cards 527 friend class Par_MarkFromRootsClosure; // to access _restart_addr 528 // ... and for clearing cards 529 friend class Par_ConcMarkingClosure; // to access _restart_addr etc. 530 friend class MarkFromRootsVerifyClosure; // to access _restart_addr 531 friend class PushAndMarkVerifyClosure; // -- ditto -- 532 friend class MarkRefsIntoAndScanClosure; // to access _overflow_list 533 friend class PushAndMarkClosure; // -- ditto -- 534 friend class Par_PushAndMarkClosure; // -- ditto -- 535 friend class CMSKeepAliveClosure; // -- ditto -- 536 friend class CMSDrainMarkingStackClosure; // -- ditto -- 537 friend class CMSInnerParMarkAndPushClosure; // -- ditto -- 538 NOT_PRODUCT(friend class ScanMarkedObjectsAgainClosure;) // assertion on _overflow_list 539 friend class ReleaseForegroundGC; // to access _foregroundGCShouldWait 540 friend class VM_CMS_Operation; 541 friend class VM_CMS_Initial_Mark; 542 friend class VM_CMS_Final_Remark; 543 friend class TraceCMSMemoryManagerStats; 544 545 private: 546 jlong _time_of_last_gc; 547 void update_time_of_last_gc(jlong now) { 548 _time_of_last_gc = now; 549 } 550 551 OopTaskQueueSet* _task_queues; 552 553 // Overflow list of grey objects, threaded through mark-word 554 // Manipulated with CAS in the parallel/multi-threaded case. 555 oop _overflow_list; 556 // The following array-pair keeps track of mark words 557 // displaced for accomodating overflow list above. 558 // This code will likely be revisited under RFE#4922830. 559 Stack<oop, mtGC> _preserved_oop_stack; 560 Stack<markOop, mtGC> _preserved_mark_stack; 561 562 int* _hash_seed; 563 564 // In support of multi-threaded concurrent phases 565 YieldingFlexibleWorkGang* _conc_workers; 566 567 // Performance Counters 568 CollectorCounters* _gc_counters; 569 570 // Initialization Errors 571 bool _completed_initialization; 572 573 // In support of ExplicitGCInvokesConcurrent 574 static bool _full_gc_requested; 575 unsigned int _collection_count_start; 576 577 // Should we unload classes this concurrent cycle? 578 bool _should_unload_classes; 579 unsigned int _concurrent_cycles_since_last_unload; 580 unsigned int concurrent_cycles_since_last_unload() const { 581 return _concurrent_cycles_since_last_unload; 582 } 583 // Did we (allow) unload classes in the previous concurrent cycle? 584 bool unloaded_classes_last_cycle() const { 585 return concurrent_cycles_since_last_unload() == 0; 586 } 587 // Root scanning options for perm gen 588 int _roots_scanning_options; 589 int roots_scanning_options() const { return _roots_scanning_options; } 590 void add_root_scanning_option(int o) { _roots_scanning_options |= o; } 591 void remove_root_scanning_option(int o) { _roots_scanning_options &= ~o; } 592 593 // Verification support 594 CMSBitMap _verification_mark_bm; 595 void verify_after_remark_work_1(); 596 void verify_after_remark_work_2(); 597 598 // true if any verification flag is on. 599 bool _verifying; 600 bool verifying() const { return _verifying; } 601 void set_verifying(bool v) { _verifying = v; } 602 603 // Collector policy 604 ConcurrentMarkSweepPolicy* _collector_policy; 605 ConcurrentMarkSweepPolicy* collector_policy() { return _collector_policy; } 606 607 void set_did_compact(bool v); 608 609 // XXX Move these to CMSStats ??? FIX ME !!! 610 elapsedTimer _inter_sweep_timer; // time between sweeps 611 elapsedTimer _intra_sweep_timer; // time _in_ sweeps 612 // padded decaying average estimates of the above 613 AdaptivePaddedAverage _inter_sweep_estimate; 614 AdaptivePaddedAverage _intra_sweep_estimate; 615 616 protected: 617 ConcurrentMarkSweepGeneration* _cmsGen; // old gen (CMS) 618 MemRegion _span; // span covering above two 619 CardTableRS* _ct; // card table 620 621 // CMS marking support structures 622 CMSBitMap _markBitMap; 623 CMSBitMap _modUnionTable; 624 CMSMarkStack _markStack; 625 626 HeapWord* _restart_addr; // in support of marking stack overflow 627 void lower_restart_addr(HeapWord* low); 628 629 // Counters in support of marking stack / work queue overflow handling: 630 // a non-zero value indicates certain types of overflow events during 631 // the current CMS cycle and could lead to stack resizing efforts at 632 // an opportune future time. 633 size_t _ser_pmc_preclean_ovflw; 634 size_t _ser_pmc_remark_ovflw; 635 size_t _par_pmc_remark_ovflw; 636 size_t _ser_kac_preclean_ovflw; 637 size_t _ser_kac_ovflw; 638 size_t _par_kac_ovflw; 639 NOT_PRODUCT(ssize_t _num_par_pushes;) 640 641 // ("Weak") Reference processing support 642 ReferenceProcessor* _ref_processor; 643 CMSIsAliveClosure _is_alive_closure; 644 // keep this textually after _markBitMap and _span; c'tor dependency 645 646 ConcurrentMarkSweepThread* _cmsThread; // the thread doing the work 647 ModUnionClosure _modUnionClosure; 648 ModUnionClosurePar _modUnionClosurePar; 649 650 // CMS abstract state machine 651 // initial_state: Idling 652 // next_state(Idling) = {Marking} 653 // next_state(Marking) = {Precleaning, Sweeping} 654 // next_state(Precleaning) = {AbortablePreclean, FinalMarking} 655 // next_state(AbortablePreclean) = {FinalMarking} 656 // next_state(FinalMarking) = {Sweeping} 657 // next_state(Sweeping) = {Resizing} 658 // next_state(Resizing) = {Resetting} 659 // next_state(Resetting) = {Idling} 660 // The numeric values below are chosen so that: 661 // . _collectorState <= Idling == post-sweep && pre-mark 662 // . _collectorState in (Idling, Sweeping) == {initial,final}marking || 663 // precleaning || abortablePrecleanb 664 public: 665 enum CollectorState { 666 Resizing = 0, 667 Resetting = 1, 668 Idling = 2, 669 InitialMarking = 3, 670 Marking = 4, 671 Precleaning = 5, 672 AbortablePreclean = 6, 673 FinalMarking = 7, 674 Sweeping = 8 675 }; 676 protected: 677 static CollectorState _collectorState; 678 679 // State related to prologue/epilogue invocation for my generations 680 bool _between_prologue_and_epilogue; 681 682 // Signalling/State related to coordination between fore- and backgroud GC 683 // Note: When the baton has been passed from background GC to foreground GC, 684 // _foregroundGCIsActive is true and _foregroundGCShouldWait is false. 685 static bool _foregroundGCIsActive; // true iff foreground collector is active or 686 // wants to go active 687 static bool _foregroundGCShouldWait; // true iff background GC is active and has not 688 // yet passed the baton to the foreground GC 689 690 // Support for CMSScheduleRemark (abortable preclean) 691 bool _abort_preclean; 692 bool _start_sampling; 693 694 int _numYields; 695 size_t _numDirtyCards; 696 size_t _sweep_count; 697 // number of full gc's since the last concurrent gc. 698 uint _full_gcs_since_conc_gc; 699 700 // occupancy used for bootstrapping stats 701 double _bootstrap_occupancy; 702 703 // timer 704 elapsedTimer _timer; 705 706 // Timing, allocation and promotion statistics, used for scheduling. 707 CMSStats _stats; 708 709 // Allocation limits installed in the young gen, used only in 710 // CMSIncrementalMode. When an allocation in the young gen would cross one of 711 // these limits, the cms generation is notified and the cms thread is started 712 // or stopped, respectively. 713 HeapWord* _icms_start_limit; 714 HeapWord* _icms_stop_limit; 715 716 enum CMS_op_type { 717 CMS_op_checkpointRootsInitial, 718 CMS_op_checkpointRootsFinal 719 }; 720 721 void do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause); 722 bool stop_world_and_do(CMS_op_type op); 723 724 OopTaskQueueSet* task_queues() { return _task_queues; } 725 int* hash_seed(int i) { return &_hash_seed[i]; } 726 YieldingFlexibleWorkGang* conc_workers() { return _conc_workers; } 727 728 // Support for parallelizing Eden rescan in CMS remark phase 729 void sample_eden(); // ... sample Eden space top 730 731 private: 732 // Support for parallelizing young gen rescan in CMS remark phase 733 Generation* _young_gen; // the younger gen 734 HeapWord** _top_addr; // ... Top of Eden 735 HeapWord** _end_addr; // ... End of Eden 736 HeapWord** _eden_chunk_array; // ... Eden partitioning array 737 size_t _eden_chunk_index; // ... top (exclusive) of array 738 size_t _eden_chunk_capacity; // ... max entries in array 739 740 // Support for parallelizing survivor space rescan 741 HeapWord** _survivor_chunk_array; 742 size_t _survivor_chunk_index; 743 size_t _survivor_chunk_capacity; 744 size_t* _cursor; 745 ChunkArray* _survivor_plab_array; 746 747 // Support for marking stack overflow handling 748 bool take_from_overflow_list(size_t num, CMSMarkStack* to_stack); 749 bool par_take_from_overflow_list(size_t num, 750 OopTaskQueue* to_work_q, 751 int no_of_gc_threads); 752 void push_on_overflow_list(oop p); 753 void par_push_on_overflow_list(oop p); 754 // the following is, obviously, not, in general, "MT-stable" 755 bool overflow_list_is_empty() const; 756 757 void preserve_mark_if_necessary(oop p); 758 void par_preserve_mark_if_necessary(oop p); 759 void preserve_mark_work(oop p, markOop m); 760 void restore_preserved_marks_if_any(); 761 NOT_PRODUCT(bool no_preserved_marks() const;) 762 // in support of testing overflow code 763 NOT_PRODUCT(int _overflow_counter;) 764 NOT_PRODUCT(bool simulate_overflow();) // sequential 765 NOT_PRODUCT(bool par_simulate_overflow();) // MT version 766 767 // CMS work methods 768 void checkpointRootsInitialWork(bool asynch); // initial checkpoint work 769 770 // a return value of false indicates failure due to stack overflow 771 bool markFromRootsWork(bool asynch); // concurrent marking work 772 773 public: // FIX ME!!! only for testing 774 bool do_marking_st(bool asynch); // single-threaded marking 775 bool do_marking_mt(bool asynch); // multi-threaded marking 776 777 private: 778 779 // concurrent precleaning work 780 size_t preclean_mod_union_table(ConcurrentMarkSweepGeneration* gen, 781 ScanMarkedObjectsAgainCarefullyClosure* cl); 782 size_t preclean_card_table(ConcurrentMarkSweepGeneration* gen, 783 ScanMarkedObjectsAgainCarefullyClosure* cl); 784 // Does precleaning work, returning a quantity indicative of 785 // the amount of "useful work" done. 786 size_t preclean_work(bool clean_refs, bool clean_survivors); 787 void preclean_klasses(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock); 788 void abortable_preclean(); // Preclean while looking for possible abort 789 void initialize_sequential_subtasks_for_young_gen_rescan(int i); 790 // Helper function for above; merge-sorts the per-thread plab samples 791 void merge_survivor_plab_arrays(ContiguousSpace* surv, int no_of_gc_threads); 792 // Resets (i.e. clears) the per-thread plab sample vectors 793 void reset_survivor_plab_arrays(); 794 795 // final (second) checkpoint work 796 void checkpointRootsFinalWork(bool asynch, bool clear_all_soft_refs, 797 bool init_mark_was_synchronous); 798 // work routine for parallel version of remark 799 void do_remark_parallel(); 800 // work routine for non-parallel version of remark 801 void do_remark_non_parallel(); 802 // reference processing work routine (during second checkpoint) 803 void refProcessingWork(bool asynch, bool clear_all_soft_refs); 804 805 // concurrent sweeping work 806 void sweepWork(ConcurrentMarkSweepGeneration* gen, bool asynch); 807 808 // (concurrent) resetting of support data structures 809 void reset(bool asynch); 810 811 // Clear _expansion_cause fields of constituent generations 812 void clear_expansion_cause(); 813 814 // An auxilliary method used to record the ends of 815 // used regions of each generation to limit the extent of sweep 816 void save_sweep_limits(); 817 818 // A work method used by foreground collection to determine 819 // what type of collection (compacting or not, continuing or fresh) 820 // it should do. 821 void decide_foreground_collection_type(bool clear_all_soft_refs, 822 bool* should_compact, bool* should_start_over); 823 824 // A work method used by the foreground collector to do 825 // a mark-sweep-compact. 826 void do_compaction_work(bool clear_all_soft_refs); 827 828 // A work method used by the foreground collector to do 829 // a mark-sweep, after taking over from a possibly on-going 830 // concurrent mark-sweep collection. 831 void do_mark_sweep_work(bool clear_all_soft_refs, 832 CollectorState first_state, bool should_start_over); 833 834 // If the backgrould GC is active, acquire control from the background 835 // GC and do the collection. 836 void acquire_control_and_collect(bool full, bool clear_all_soft_refs); 837 838 // For synchronizing passing of control from background to foreground 839 // GC. waitForForegroundGC() is called by the background 840 // collector. It if had to wait for a foreground collection, 841 // it returns true and the background collection should assume 842 // that the collection was finished by the foreground 843 // collector. 844 bool waitForForegroundGC(); 845 846 // Incremental mode triggering: recompute the icms duty cycle and set the 847 // allocation limits in the young gen. 848 void icms_update_allocation_limits(); 849 850 size_t block_size_using_printezis_bits(HeapWord* addr) const; 851 size_t block_size_if_printezis_bits(HeapWord* addr) const; 852 HeapWord* next_card_start_after_block(HeapWord* addr) const; 853 854 void setup_cms_unloading_and_verification_state(); 855 public: 856 CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, 857 CardTableRS* ct, 858 ConcurrentMarkSweepPolicy* cp); 859 ConcurrentMarkSweepThread* cmsThread() { return _cmsThread; } 860 861 ReferenceProcessor* ref_processor() { return _ref_processor; } 862 void ref_processor_init(); 863 864 Mutex* bitMapLock() const { return _markBitMap.lock(); } 865 static CollectorState abstract_state() { return _collectorState; } 866 867 bool should_abort_preclean() const; // Whether preclean should be aborted. 868 size_t get_eden_used() const; 869 size_t get_eden_capacity() const; 870 871 ConcurrentMarkSweepGeneration* cmsGen() { return _cmsGen; } 872 873 // locking checks 874 NOT_PRODUCT(static bool have_cms_token();) 875 876 // XXXPERM bool should_collect(bool full, size_t size, bool tlab); 877 bool shouldConcurrentCollect(); 878 879 void collect(bool full, 880 bool clear_all_soft_refs, 881 size_t size, 882 bool tlab); 883 void collect_in_background(bool clear_all_soft_refs); 884 void collect_in_foreground(bool clear_all_soft_refs); 885 886 // In support of ExplicitGCInvokesConcurrent 887 static void request_full_gc(unsigned int full_gc_count); 888 // Should we unload classes in a particular concurrent cycle? 889 bool should_unload_classes() const { 890 return _should_unload_classes; 891 } 892 void update_should_unload_classes(); 893 894 void direct_allocated(HeapWord* start, size_t size); 895 896 // Object is dead if not marked and current phase is sweeping. 897 bool is_dead_obj(oop obj) const; 898 899 // After a promotion (of "start"), do any necessary marking. 900 // If "par", then it's being done by a parallel GC thread. 901 // The last two args indicate if we need precise marking 902 // and if so the size of the object so it can be dirtied 903 // in its entirety. 904 void promoted(bool par, HeapWord* start, 905 bool is_obj_array, size_t obj_size); 906 907 HeapWord* allocation_limit_reached(Space* space, HeapWord* top, 908 size_t word_size); 909 910 void getFreelistLocks() const; 911 void releaseFreelistLocks() const; 912 bool haveFreelistLocks() const; 913 914 // Adjust size of underlying generation 915 void compute_new_size(); 916 917 // GC prologue and epilogue 918 void gc_prologue(bool full); 919 void gc_epilogue(bool full); 920 921 jlong time_of_last_gc(jlong now) { 922 if (_collectorState <= Idling) { 923 // gc not in progress 924 return _time_of_last_gc; 925 } else { 926 // collection in progress 927 return now; 928 } 929 } 930 931 // Support for parallel remark of survivor space 932 void* get_data_recorder(int thr_num); 933 934 CMSBitMap* markBitMap() { return &_markBitMap; } 935 void directAllocated(HeapWord* start, size_t size); 936 937 // main CMS steps and related support 938 void checkpointRootsInitial(bool asynch); 939 bool markFromRoots(bool asynch); // a return value of false indicates failure 940 // due to stack overflow 941 void preclean(); 942 void checkpointRootsFinal(bool asynch, bool clear_all_soft_refs, 943 bool init_mark_was_synchronous); 944 void sweep(bool asynch); 945 946 // Check that the currently executing thread is the expected 947 // one (foreground collector or background collector). 948 static void check_correct_thread_executing() PRODUCT_RETURN; 949 // XXXPERM void print_statistics() PRODUCT_RETURN; 950 951 bool is_cms_reachable(HeapWord* addr); 952 953 // Performance Counter Support 954 CollectorCounters* counters() { return _gc_counters; } 955 956 // timer stuff 957 void startTimer() { assert(!_timer.is_active(), "Error"); _timer.start(); } 958 void stopTimer() { assert( _timer.is_active(), "Error"); _timer.stop(); } 959 void resetTimer() { assert(!_timer.is_active(), "Error"); _timer.reset(); } 960 double timerValue() { assert(!_timer.is_active(), "Error"); return _timer.seconds(); } 961 962 int yields() { return _numYields; } 963 void resetYields() { _numYields = 0; } 964 void incrementYields() { _numYields++; } 965 void resetNumDirtyCards() { _numDirtyCards = 0; } 966 void incrementNumDirtyCards(size_t num) { _numDirtyCards += num; } 967 size_t numDirtyCards() { return _numDirtyCards; } 968 969 static bool foregroundGCShouldWait() { return _foregroundGCShouldWait; } 970 static void set_foregroundGCShouldWait(bool v) { _foregroundGCShouldWait = v; } 971 static bool foregroundGCIsActive() { return _foregroundGCIsActive; } 972 static void set_foregroundGCIsActive(bool v) { _foregroundGCIsActive = v; } 973 size_t sweep_count() const { return _sweep_count; } 974 void increment_sweep_count() { _sweep_count++; } 975 976 // Timers/stats for gc scheduling and incremental mode pacing. 977 CMSStats& stats() { return _stats; } 978 979 // Convenience methods that check whether CMSIncrementalMode is enabled and 980 // forward to the corresponding methods in ConcurrentMarkSweepThread. 981 static void start_icms(); 982 static void stop_icms(); // Called at the end of the cms cycle. 983 static void disable_icms(); // Called before a foreground collection. 984 static void enable_icms(); // Called after a foreground collection. 985 void icms_wait(); // Called at yield points. 986 987 // Adaptive size policy 988 CMSAdaptiveSizePolicy* size_policy(); 989 CMSGCAdaptivePolicyCounters* gc_adaptive_policy_counters(); 990 991 static void print_on_error(outputStream* st); 992 993 // debugging 994 void verify(); 995 bool verify_after_remark(bool silent = VerifySilently); 996 void verify_ok_to_terminate() const PRODUCT_RETURN; 997 void verify_work_stacks_empty() const PRODUCT_RETURN; 998 void verify_overflow_empty() const PRODUCT_RETURN; 999 1000 // convenience methods in support of debugging 1001 static const size_t skip_header_HeapWords() PRODUCT_RETURN0; 1002 HeapWord* block_start(const void* p) const PRODUCT_RETURN0; 1003 1004 // accessors 1005 CMSMarkStack* verification_mark_stack() { return &_markStack; } 1006 CMSBitMap* verification_mark_bm() { return &_verification_mark_bm; } 1007 1008 // Initialization errors 1009 bool completed_initialization() { return _completed_initialization; } 1010 }; 1011 1012 class CMSExpansionCause : public AllStatic { 1013 public: 1014 enum Cause { 1015 _no_expansion, 1016 _satisfy_free_ratio, 1017 _satisfy_promotion, 1018 _satisfy_allocation, 1019 _allocate_par_lab, 1020 _allocate_par_spooling_space, 1021 _adaptive_size_policy 1022 }; 1023 // Return a string describing the cause of the expansion. 1024 static const char* to_string(CMSExpansionCause::Cause cause); 1025 }; 1026 1027 class ConcurrentMarkSweepGeneration: public CardGeneration { 1028 friend class VMStructs; 1029 friend class ConcurrentMarkSweepThread; 1030 friend class ConcurrentMarkSweep; 1031 friend class CMSCollector; 1032 protected: 1033 static CMSCollector* _collector; // the collector that collects us 1034 CompactibleFreeListSpace* _cmsSpace; // underlying space (only one for now) 1035 1036 // Performance Counters 1037 GenerationCounters* _gen_counters; 1038 GSpaceCounters* _space_counters; 1039 1040 // Words directly allocated, used by CMSStats. 1041 size_t _direct_allocated_words; 1042 1043 // Non-product stat counters 1044 NOT_PRODUCT( 1045 size_t _numObjectsPromoted; 1046 size_t _numWordsPromoted; 1047 size_t _numObjectsAllocated; 1048 size_t _numWordsAllocated; 1049 ) 1050 1051 // Used for sizing decisions 1052 bool _incremental_collection_failed; 1053 bool incremental_collection_failed() { 1054 return _incremental_collection_failed; 1055 } 1056 void set_incremental_collection_failed() { 1057 _incremental_collection_failed = true; 1058 } 1059 void clear_incremental_collection_failed() { 1060 _incremental_collection_failed = false; 1061 } 1062 1063 // accessors 1064 void set_expansion_cause(CMSExpansionCause::Cause v) { _expansion_cause = v;} 1065 CMSExpansionCause::Cause expansion_cause() const { return _expansion_cause; } 1066 1067 private: 1068 // For parallel young-gen GC support. 1069 CMSParGCThreadState** _par_gc_thread_states; 1070 1071 // Reason generation was expanded 1072 CMSExpansionCause::Cause _expansion_cause; 1073 1074 // In support of MinChunkSize being larger than min object size 1075 const double _dilatation_factor; 1076 1077 enum CollectionTypes { 1078 Concurrent_collection_type = 0, 1079 MS_foreground_collection_type = 1, 1080 MSC_foreground_collection_type = 2, 1081 Unknown_collection_type = 3 1082 }; 1083 1084 CollectionTypes _debug_collection_type; 1085 1086 // True if a compactiing collection was done. 1087 bool _did_compact; 1088 bool did_compact() { return _did_compact; } 1089 1090 // Fraction of current occupancy at which to start a CMS collection which 1091 // will collect this generation (at least). 1092 double _initiating_occupancy; 1093 1094 protected: 1095 // Shrink generation by specified size (returns false if unable to shrink) 1096 void shrink_free_list_by(size_t bytes); 1097 1098 // Update statistics for GC 1099 virtual void update_gc_stats(int level, bool full); 1100 1101 // Maximum available space in the generation (including uncommitted) 1102 // space. 1103 size_t max_available() const; 1104 1105 // getter and initializer for _initiating_occupancy field. 1106 double initiating_occupancy() const { return _initiating_occupancy; } 1107 void init_initiating_occupancy(intx io, uintx tr); 1108 1109 public: 1110 ConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, 1111 int level, CardTableRS* ct, 1112 bool use_adaptive_freelists, 1113 FreeBlockDictionary<FreeChunk>::DictionaryChoice); 1114 1115 // Accessors 1116 CMSCollector* collector() const { return _collector; } 1117 static void set_collector(CMSCollector* collector) { 1118 assert(_collector == NULL, "already set"); 1119 _collector = collector; 1120 } 1121 CompactibleFreeListSpace* cmsSpace() const { return _cmsSpace; } 1122 1123 Mutex* freelistLock() const; 1124 1125 virtual Generation::Name kind() { return Generation::ConcurrentMarkSweep; } 1126 1127 // Adaptive size policy 1128 CMSAdaptiveSizePolicy* size_policy(); 1129 1130 void set_did_compact(bool v) { _did_compact = v; } 1131 1132 bool refs_discovery_is_atomic() const { return false; } 1133 bool refs_discovery_is_mt() const { 1134 // Note: CMS does MT-discovery during the parallel-remark 1135 // phases. Use ReferenceProcessorMTMutator to make refs 1136 // discovery MT-safe during such phases or other parallel 1137 // discovery phases in the future. This may all go away 1138 // if/when we decide that refs discovery is sufficiently 1139 // rare that the cost of the CAS's involved is in the 1140 // noise. That's a measurement that should be done, and 1141 // the code simplified if that turns out to be the case. 1142 return ConcGCThreads > 1; 1143 } 1144 1145 // Override 1146 virtual void ref_processor_init(); 1147 1148 // Grow generation by specified size (returns false if unable to grow) 1149 bool grow_by(size_t bytes); 1150 // Grow generation to reserved size. 1151 bool grow_to_reserved(); 1152 1153 void clear_expansion_cause() { _expansion_cause = CMSExpansionCause::_no_expansion; } 1154 1155 // Space enquiries 1156 size_t capacity() const; 1157 size_t used() const; 1158 size_t free() const; 1159 double occupancy() const { return ((double)used())/((double)capacity()); } 1160 size_t contiguous_available() const; 1161 size_t unsafe_max_alloc_nogc() const; 1162 1163 // over-rides 1164 MemRegion used_region() const; 1165 MemRegion used_region_at_save_marks() const; 1166 1167 // Does a "full" (forced) collection invoked on this generation collect 1168 // all younger generations as well? Note that the second conjunct is a 1169 // hack to allow the collection of the younger gen first if the flag is 1170 // set. This is better than using th policy's should_collect_gen0_first() 1171 // since that causes us to do an extra unnecessary pair of restart-&-stop-world. 1172 virtual bool full_collects_younger_generations() const { 1173 return UseCMSCompactAtFullCollection && !CollectGen0First; 1174 } 1175 1176 void space_iterate(SpaceClosure* blk, bool usedOnly = false); 1177 1178 // Support for compaction 1179 CompactibleSpace* first_compaction_space() const; 1180 // Adjust quantites in the generation affected by 1181 // the compaction. 1182 void reset_after_compaction(); 1183 1184 // Allocation support 1185 HeapWord* allocate(size_t size, bool tlab); 1186 HeapWord* have_lock_and_allocate(size_t size, bool tlab); 1187 oop promote(oop obj, size_t obj_size); 1188 HeapWord* par_allocate(size_t size, bool tlab) { 1189 return allocate(size, tlab); 1190 } 1191 1192 // Incremental mode triggering. 1193 HeapWord* allocation_limit_reached(Space* space, HeapWord* top, 1194 size_t word_size); 1195 1196 // Used by CMSStats to track direct allocation. The value is sampled and 1197 // reset after each young gen collection. 1198 size_t direct_allocated_words() const { return _direct_allocated_words; } 1199 void reset_direct_allocated_words() { _direct_allocated_words = 0; } 1200 1201 // Overrides for parallel promotion. 1202 virtual oop par_promote(int thread_num, 1203 oop obj, markOop m, size_t word_sz); 1204 // This one should not be called for CMS. 1205 virtual void par_promote_alloc_undo(int thread_num, 1206 HeapWord* obj, size_t word_sz); 1207 virtual void par_promote_alloc_done(int thread_num); 1208 virtual void par_oop_since_save_marks_iterate_done(int thread_num); 1209 1210 virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes) const; 1211 1212 // Inform this (non-young) generation that a promotion failure was 1213 // encountered during a collection of a younger generation that 1214 // promotes into this generation. 1215 virtual void promotion_failure_occurred(); 1216 1217 bool should_collect(bool full, size_t size, bool tlab); 1218 virtual bool should_concurrent_collect() const; 1219 virtual bool is_too_full() const; 1220 void collect(bool full, 1221 bool clear_all_soft_refs, 1222 size_t size, 1223 bool tlab); 1224 1225 HeapWord* expand_and_allocate(size_t word_size, 1226 bool tlab, 1227 bool parallel = false); 1228 1229 // GC prologue and epilogue 1230 void gc_prologue(bool full); 1231 void gc_prologue_work(bool full, bool registerClosure, 1232 ModUnionClosure* modUnionClosure); 1233 void gc_epilogue(bool full); 1234 void gc_epilogue_work(bool full); 1235 1236 // Time since last GC of this generation 1237 jlong time_of_last_gc(jlong now) { 1238 return collector()->time_of_last_gc(now); 1239 } 1240 void update_time_of_last_gc(jlong now) { 1241 collector()-> update_time_of_last_gc(now); 1242 } 1243 1244 // Allocation failure 1245 void expand(size_t bytes, size_t expand_bytes, 1246 CMSExpansionCause::Cause cause); 1247 virtual bool expand(size_t bytes, size_t expand_bytes); 1248 void shrink(size_t bytes); 1249 void shrink_by(size_t bytes); 1250 HeapWord* expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz); 1251 bool expand_and_ensure_spooling_space(PromotionInfo* promo); 1252 1253 // Iteration support and related enquiries 1254 void save_marks(); 1255 bool no_allocs_since_save_marks(); 1256 void object_iterate_since_last_GC(ObjectClosure* cl); 1257 void younger_refs_iterate(OopsInGenClosure* cl); 1258 1259 // Iteration support specific to CMS generations 1260 void save_sweep_limit(); 1261 1262 // More iteration support 1263 virtual void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1264 virtual void oop_iterate(ExtendedOopClosure* cl); 1265 virtual void safe_object_iterate(ObjectClosure* cl); 1266 virtual void object_iterate(ObjectClosure* cl); 1267 1268 // Need to declare the full complement of closures, whether we'll 1269 // override them or not, or get message from the compiler: 1270 // oop_since_save_marks_iterate_nv hides virtual function... 1271 #define CMS_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 1272 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); 1273 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DECL) 1274 1275 // Smart allocation XXX -- move to CFLSpace? 1276 void setNearLargestChunk(); 1277 bool isNearLargestChunk(HeapWord* addr); 1278 1279 // Get the chunk at the end of the space. Delagates to 1280 // the space. 1281 FreeChunk* find_chunk_at_end(); 1282 1283 void post_compact(); 1284 1285 // Debugging 1286 void prepare_for_verify(); 1287 void verify(); 1288 void print_statistics() PRODUCT_RETURN; 1289 1290 // Performance Counters support 1291 virtual void update_counters(); 1292 virtual void update_counters(size_t used); 1293 void initialize_performance_counters(); 1294 CollectorCounters* counters() { return collector()->counters(); } 1295 1296 // Support for parallel remark of survivor space 1297 void* get_data_recorder(int thr_num) { 1298 //Delegate to collector 1299 return collector()->get_data_recorder(thr_num); 1300 } 1301 1302 // Printing 1303 const char* name() const; 1304 virtual const char* short_name() const { return "CMS"; } 1305 void print() const; 1306 void printOccupancy(const char* s); 1307 bool must_be_youngest() const { return false; } 1308 bool must_be_oldest() const { return true; } 1309 1310 // Resize the generation after a compacting GC. The 1311 // generation can be treated as a contiguous space 1312 // after the compaction. 1313 virtual void compute_new_size(); 1314 // Resize the generation after a non-compacting 1315 // collection. 1316 void compute_new_size_free_list(); 1317 1318 CollectionTypes debug_collection_type() { return _debug_collection_type; } 1319 void rotate_debug_collection_type(); 1320 }; 1321 1322 class ASConcurrentMarkSweepGeneration : public ConcurrentMarkSweepGeneration { 1323 1324 // Return the size policy from the heap's collector 1325 // policy casted to CMSAdaptiveSizePolicy*. 1326 CMSAdaptiveSizePolicy* cms_size_policy() const; 1327 1328 // Resize the generation based on the adaptive size 1329 // policy. 1330 void resize(size_t cur_promo, size_t desired_promo); 1331 1332 // Return the GC counters from the collector policy 1333 CMSGCAdaptivePolicyCounters* gc_adaptive_policy_counters(); 1334 1335 virtual void shrink_by(size_t bytes); 1336 1337 public: 1338 ASConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, 1339 int level, CardTableRS* ct, 1340 bool use_adaptive_freelists, 1341 FreeBlockDictionary<FreeChunk>::DictionaryChoice 1342 dictionaryChoice) : 1343 ConcurrentMarkSweepGeneration(rs, initial_byte_size, level, ct, 1344 use_adaptive_freelists, dictionaryChoice) {} 1345 1346 virtual const char* short_name() const { return "ASCMS"; } 1347 virtual Generation::Name kind() { return Generation::ASConcurrentMarkSweep; } 1348 1349 virtual void update_counters(); 1350 virtual void update_counters(size_t used); 1351 }; 1352 1353 // 1354 // Closures of various sorts used by CMS to accomplish its work 1355 // 1356 1357 // This closure is used to check that a certain set of oops is empty. 1358 class FalseClosure: public OopClosure { 1359 public: 1360 void do_oop(oop* p) { guarantee(false, "Should be an empty set"); } 1361 void do_oop(narrowOop* p) { guarantee(false, "Should be an empty set"); } 1362 }; 1363 1364 // This closure is used to do concurrent marking from the roots 1365 // following the first checkpoint. 1366 class MarkFromRootsClosure: public BitMapClosure { 1367 CMSCollector* _collector; 1368 MemRegion _span; 1369 CMSBitMap* _bitMap; 1370 CMSBitMap* _mut; 1371 CMSMarkStack* _markStack; 1372 bool _yield; 1373 int _skipBits; 1374 HeapWord* _finger; 1375 HeapWord* _threshold; 1376 DEBUG_ONLY(bool _verifying;) 1377 1378 public: 1379 MarkFromRootsClosure(CMSCollector* collector, MemRegion span, 1380 CMSBitMap* bitMap, 1381 CMSMarkStack* markStack, 1382 bool should_yield, bool verifying = false); 1383 bool do_bit(size_t offset); 1384 void reset(HeapWord* addr); 1385 inline void do_yield_check(); 1386 1387 private: 1388 void scanOopsInOop(HeapWord* ptr); 1389 void do_yield_work(); 1390 }; 1391 1392 // This closure is used to do concurrent multi-threaded 1393 // marking from the roots following the first checkpoint. 1394 // XXX This should really be a subclass of The serial version 1395 // above, but i have not had the time to refactor things cleanly. 1396 // That willbe done for Dolphin. 1397 class Par_MarkFromRootsClosure: public BitMapClosure { 1398 CMSCollector* _collector; 1399 MemRegion _whole_span; 1400 MemRegion _span; 1401 CMSBitMap* _bit_map; 1402 CMSBitMap* _mut; 1403 OopTaskQueue* _work_queue; 1404 CMSMarkStack* _overflow_stack; 1405 bool _yield; 1406 int _skip_bits; 1407 HeapWord* _finger; 1408 HeapWord* _threshold; 1409 CMSConcMarkingTask* _task; 1410 public: 1411 Par_MarkFromRootsClosure(CMSConcMarkingTask* task, CMSCollector* collector, 1412 MemRegion span, 1413 CMSBitMap* bit_map, 1414 OopTaskQueue* work_queue, 1415 CMSMarkStack* overflow_stack, 1416 bool should_yield); 1417 bool do_bit(size_t offset); 1418 inline void do_yield_check(); 1419 1420 private: 1421 void scan_oops_in_oop(HeapWord* ptr); 1422 void do_yield_work(); 1423 bool get_work_from_overflow_stack(); 1424 }; 1425 1426 // The following closures are used to do certain kinds of verification of 1427 // CMS marking. 1428 class PushAndMarkVerifyClosure: public CMSOopClosure { 1429 CMSCollector* _collector; 1430 MemRegion _span; 1431 CMSBitMap* _verification_bm; 1432 CMSBitMap* _cms_bm; 1433 CMSMarkStack* _mark_stack; 1434 protected: 1435 void do_oop(oop p); 1436 template <class T> inline void do_oop_work(T *p) { 1437 oop obj = oopDesc::load_decode_heap_oop(p); 1438 do_oop(obj); 1439 } 1440 public: 1441 PushAndMarkVerifyClosure(CMSCollector* cms_collector, 1442 MemRegion span, 1443 CMSBitMap* verification_bm, 1444 CMSBitMap* cms_bm, 1445 CMSMarkStack* mark_stack); 1446 void do_oop(oop* p); 1447 void do_oop(narrowOop* p); 1448 1449 // Deal with a stack overflow condition 1450 void handle_stack_overflow(HeapWord* lost); 1451 }; 1452 1453 class MarkFromRootsVerifyClosure: public BitMapClosure { 1454 CMSCollector* _collector; 1455 MemRegion _span; 1456 CMSBitMap* _verification_bm; 1457 CMSBitMap* _cms_bm; 1458 CMSMarkStack* _mark_stack; 1459 HeapWord* _finger; 1460 PushAndMarkVerifyClosure _pam_verify_closure; 1461 public: 1462 MarkFromRootsVerifyClosure(CMSCollector* collector, MemRegion span, 1463 CMSBitMap* verification_bm, 1464 CMSBitMap* cms_bm, 1465 CMSMarkStack* mark_stack); 1466 bool do_bit(size_t offset); 1467 void reset(HeapWord* addr); 1468 }; 1469 1470 1471 // This closure is used to check that a certain set of bits is 1472 // "empty" (i.e. the bit vector doesn't have any 1-bits). 1473 class FalseBitMapClosure: public BitMapClosure { 1474 public: 1475 bool do_bit(size_t offset) { 1476 guarantee(false, "Should not have a 1 bit"); 1477 return true; 1478 } 1479 }; 1480 1481 // This closure is used during the second checkpointing phase 1482 // to rescan the marked objects on the dirty cards in the mod 1483 // union table and the card table proper. It's invoked via 1484 // MarkFromDirtyCardsClosure below. It uses either 1485 // [Par_]MarkRefsIntoAndScanClosure (Par_ in the parallel case) 1486 // declared in genOopClosures.hpp to accomplish some of its work. 1487 // In the parallel case the bitMap is shared, so access to 1488 // it needs to be suitably synchronized for updates by embedded 1489 // closures that update it; however, this closure itself only 1490 // reads the bit_map and because it is idempotent, is immune to 1491 // reading stale values. 1492 class ScanMarkedObjectsAgainClosure: public UpwardsObjectClosure { 1493 #ifdef ASSERT 1494 CMSCollector* _collector; 1495 MemRegion _span; 1496 union { 1497 CMSMarkStack* _mark_stack; 1498 OopTaskQueue* _work_queue; 1499 }; 1500 #endif // ASSERT 1501 bool _parallel; 1502 CMSBitMap* _bit_map; 1503 union { 1504 MarkRefsIntoAndScanClosure* _scan_closure; 1505 Par_MarkRefsIntoAndScanClosure* _par_scan_closure; 1506 }; 1507 1508 public: 1509 ScanMarkedObjectsAgainClosure(CMSCollector* collector, 1510 MemRegion span, 1511 ReferenceProcessor* rp, 1512 CMSBitMap* bit_map, 1513 CMSMarkStack* mark_stack, 1514 MarkRefsIntoAndScanClosure* cl): 1515 #ifdef ASSERT 1516 _collector(collector), 1517 _span(span), 1518 _mark_stack(mark_stack), 1519 #endif // ASSERT 1520 _parallel(false), 1521 _bit_map(bit_map), 1522 _scan_closure(cl) { } 1523 1524 ScanMarkedObjectsAgainClosure(CMSCollector* collector, 1525 MemRegion span, 1526 ReferenceProcessor* rp, 1527 CMSBitMap* bit_map, 1528 OopTaskQueue* work_queue, 1529 Par_MarkRefsIntoAndScanClosure* cl): 1530 #ifdef ASSERT 1531 _collector(collector), 1532 _span(span), 1533 _work_queue(work_queue), 1534 #endif // ASSERT 1535 _parallel(true), 1536 _bit_map(bit_map), 1537 _par_scan_closure(cl) { } 1538 1539 void do_object(oop obj) { 1540 guarantee(false, "Call do_object_b(oop, MemRegion) instead"); 1541 } 1542 bool do_object_b(oop obj) { 1543 guarantee(false, "Call do_object_b(oop, MemRegion) form instead"); 1544 return false; 1545 } 1546 bool do_object_bm(oop p, MemRegion mr); 1547 }; 1548 1549 // This closure is used during the second checkpointing phase 1550 // to rescan the marked objects on the dirty cards in the mod 1551 // union table and the card table proper. It invokes 1552 // ScanMarkedObjectsAgainClosure above to accomplish much of its work. 1553 // In the parallel case, the bit map is shared and requires 1554 // synchronized access. 1555 class MarkFromDirtyCardsClosure: public MemRegionClosure { 1556 CompactibleFreeListSpace* _space; 1557 ScanMarkedObjectsAgainClosure _scan_cl; 1558 size_t _num_dirty_cards; 1559 1560 public: 1561 MarkFromDirtyCardsClosure(CMSCollector* collector, 1562 MemRegion span, 1563 CompactibleFreeListSpace* space, 1564 CMSBitMap* bit_map, 1565 CMSMarkStack* mark_stack, 1566 MarkRefsIntoAndScanClosure* cl): 1567 _space(space), 1568 _num_dirty_cards(0), 1569 _scan_cl(collector, span, collector->ref_processor(), bit_map, 1570 mark_stack, cl) { } 1571 1572 MarkFromDirtyCardsClosure(CMSCollector* collector, 1573 MemRegion span, 1574 CompactibleFreeListSpace* space, 1575 CMSBitMap* bit_map, 1576 OopTaskQueue* work_queue, 1577 Par_MarkRefsIntoAndScanClosure* cl): 1578 _space(space), 1579 _num_dirty_cards(0), 1580 _scan_cl(collector, span, collector->ref_processor(), bit_map, 1581 work_queue, cl) { } 1582 1583 void do_MemRegion(MemRegion mr); 1584 void set_space(CompactibleFreeListSpace* space) { _space = space; } 1585 size_t num_dirty_cards() { return _num_dirty_cards; } 1586 }; 1587 1588 // This closure is used in the non-product build to check 1589 // that there are no MemRegions with a certain property. 1590 class FalseMemRegionClosure: public MemRegionClosure { 1591 void do_MemRegion(MemRegion mr) { 1592 guarantee(!mr.is_empty(), "Shouldn't be empty"); 1593 guarantee(false, "Should never be here"); 1594 } 1595 }; 1596 1597 // This closure is used during the precleaning phase 1598 // to "carefully" rescan marked objects on dirty cards. 1599 // It uses MarkRefsIntoAndScanClosure declared in genOopClosures.hpp 1600 // to accomplish some of its work. 1601 class ScanMarkedObjectsAgainCarefullyClosure: public ObjectClosureCareful { 1602 CMSCollector* _collector; 1603 MemRegion _span; 1604 bool _yield; 1605 Mutex* _freelistLock; 1606 CMSBitMap* _bitMap; 1607 CMSMarkStack* _markStack; 1608 MarkRefsIntoAndScanClosure* _scanningClosure; 1609 1610 public: 1611 ScanMarkedObjectsAgainCarefullyClosure(CMSCollector* collector, 1612 MemRegion span, 1613 CMSBitMap* bitMap, 1614 CMSMarkStack* markStack, 1615 MarkRefsIntoAndScanClosure* cl, 1616 bool should_yield): 1617 _collector(collector), 1618 _span(span), 1619 _yield(should_yield), 1620 _bitMap(bitMap), 1621 _markStack(markStack), 1622 _scanningClosure(cl) { 1623 } 1624 1625 void do_object(oop p) { 1626 guarantee(false, "call do_object_careful instead"); 1627 } 1628 1629 size_t do_object_careful(oop p) { 1630 guarantee(false, "Unexpected caller"); 1631 return 0; 1632 } 1633 1634 size_t do_object_careful_m(oop p, MemRegion mr); 1635 1636 void setFreelistLock(Mutex* m) { 1637 _freelistLock = m; 1638 _scanningClosure->set_freelistLock(m); 1639 } 1640 1641 private: 1642 inline bool do_yield_check(); 1643 1644 void do_yield_work(); 1645 }; 1646 1647 class SurvivorSpacePrecleanClosure: public ObjectClosureCareful { 1648 CMSCollector* _collector; 1649 MemRegion _span; 1650 bool _yield; 1651 CMSBitMap* _bit_map; 1652 CMSMarkStack* _mark_stack; 1653 PushAndMarkClosure* _scanning_closure; 1654 unsigned int _before_count; 1655 1656 public: 1657 SurvivorSpacePrecleanClosure(CMSCollector* collector, 1658 MemRegion span, 1659 CMSBitMap* bit_map, 1660 CMSMarkStack* mark_stack, 1661 PushAndMarkClosure* cl, 1662 unsigned int before_count, 1663 bool should_yield): 1664 _collector(collector), 1665 _span(span), 1666 _yield(should_yield), 1667 _bit_map(bit_map), 1668 _mark_stack(mark_stack), 1669 _scanning_closure(cl), 1670 _before_count(before_count) 1671 { } 1672 1673 void do_object(oop p) { 1674 guarantee(false, "call do_object_careful instead"); 1675 } 1676 1677 size_t do_object_careful(oop p); 1678 1679 size_t do_object_careful_m(oop p, MemRegion mr) { 1680 guarantee(false, "Unexpected caller"); 1681 return 0; 1682 } 1683 1684 private: 1685 inline void do_yield_check(); 1686 void do_yield_work(); 1687 }; 1688 1689 // This closure is used to accomplish the sweeping work 1690 // after the second checkpoint but before the concurrent reset 1691 // phase. 1692 // 1693 // Terminology 1694 // left hand chunk (LHC) - block of one or more chunks currently being 1695 // coalesced. The LHC is available for coalescing with a new chunk. 1696 // right hand chunk (RHC) - block that is currently being swept that is 1697 // free or garbage that can be coalesced with the LHC. 1698 // _inFreeRange is true if there is currently a LHC 1699 // _lastFreeRangeCoalesced is true if the LHC consists of more than one chunk. 1700 // _freeRangeInFreeLists is true if the LHC is in the free lists. 1701 // _freeFinger is the address of the current LHC 1702 class SweepClosure: public BlkClosureCareful { 1703 CMSCollector* _collector; // collector doing the work 1704 ConcurrentMarkSweepGeneration* _g; // Generation being swept 1705 CompactibleFreeListSpace* _sp; // Space being swept 1706 HeapWord* _limit;// the address at or above which the sweep should stop 1707 // because we do not expect newly garbage blocks 1708 // eligible for sweeping past that address. 1709 Mutex* _freelistLock; // Free list lock (in space) 1710 CMSBitMap* _bitMap; // Marking bit map (in 1711 // generation) 1712 bool _inFreeRange; // Indicates if we are in the 1713 // midst of a free run 1714 bool _freeRangeInFreeLists; 1715 // Often, we have just found 1716 // a free chunk and started 1717 // a new free range; we do not 1718 // eagerly remove this chunk from 1719 // the free lists unless there is 1720 // a possibility of coalescing. 1721 // When true, this flag indicates 1722 // that the _freeFinger below 1723 // points to a potentially free chunk 1724 // that may still be in the free lists 1725 bool _lastFreeRangeCoalesced; 1726 // free range contains chunks 1727 // coalesced 1728 bool _yield; 1729 // Whether sweeping should be 1730 // done with yields. For instance 1731 // when done by the foreground 1732 // collector we shouldn't yield. 1733 HeapWord* _freeFinger; // When _inFreeRange is set, the 1734 // pointer to the "left hand 1735 // chunk" 1736 size_t _freeRangeSize; 1737 // When _inFreeRange is set, this 1738 // indicates the accumulated size 1739 // of the "left hand chunk" 1740 NOT_PRODUCT( 1741 size_t _numObjectsFreed; 1742 size_t _numWordsFreed; 1743 size_t _numObjectsLive; 1744 size_t _numWordsLive; 1745 size_t _numObjectsAlreadyFree; 1746 size_t _numWordsAlreadyFree; 1747 FreeChunk* _last_fc; 1748 ) 1749 private: 1750 // Code that is common to a free chunk or garbage when 1751 // encountered during sweeping. 1752 void do_post_free_or_garbage_chunk(FreeChunk *fc, size_t chunkSize); 1753 // Process a free chunk during sweeping. 1754 void do_already_free_chunk(FreeChunk *fc); 1755 // Work method called when processing an already free or a 1756 // freshly garbage chunk to do a lookahead and possibly a 1757 // premptive flush if crossing over _limit. 1758 void lookahead_and_flush(FreeChunk* fc, size_t chunkSize); 1759 // Process a garbage chunk during sweeping. 1760 size_t do_garbage_chunk(FreeChunk *fc); 1761 // Process a live chunk during sweeping. 1762 size_t do_live_chunk(FreeChunk* fc); 1763 1764 // Accessors. 1765 HeapWord* freeFinger() const { return _freeFinger; } 1766 void set_freeFinger(HeapWord* v) { _freeFinger = v; } 1767 bool inFreeRange() const { return _inFreeRange; } 1768 void set_inFreeRange(bool v) { _inFreeRange = v; } 1769 bool lastFreeRangeCoalesced() const { return _lastFreeRangeCoalesced; } 1770 void set_lastFreeRangeCoalesced(bool v) { _lastFreeRangeCoalesced = v; } 1771 bool freeRangeInFreeLists() const { return _freeRangeInFreeLists; } 1772 void set_freeRangeInFreeLists(bool v) { _freeRangeInFreeLists = v; } 1773 1774 // Initialize a free range. 1775 void initialize_free_range(HeapWord* freeFinger, bool freeRangeInFreeLists); 1776 // Return this chunk to the free lists. 1777 void flush_cur_free_chunk(HeapWord* chunk, size_t size); 1778 1779 // Check if we should yield and do so when necessary. 1780 inline void do_yield_check(HeapWord* addr); 1781 1782 // Yield 1783 void do_yield_work(HeapWord* addr); 1784 1785 // Debugging/Printing 1786 void print_free_block_coalesced(FreeChunk* fc) const; 1787 1788 public: 1789 SweepClosure(CMSCollector* collector, ConcurrentMarkSweepGeneration* g, 1790 CMSBitMap* bitMap, bool should_yield); 1791 ~SweepClosure() PRODUCT_RETURN; 1792 1793 size_t do_blk_careful(HeapWord* addr); 1794 void print() const { print_on(tty); } 1795 void print_on(outputStream *st) const; 1796 }; 1797 1798 // Closures related to weak references processing 1799 1800 // During CMS' weak reference processing, this is a 1801 // work-routine/closure used to complete transitive 1802 // marking of objects as live after a certain point 1803 // in which an initial set has been completely accumulated. 1804 // This closure is currently used both during the final 1805 // remark stop-world phase, as well as during the concurrent 1806 // precleaning of the discovered reference lists. 1807 class CMSDrainMarkingStackClosure: public VoidClosure { 1808 CMSCollector* _collector; 1809 MemRegion _span; 1810 CMSMarkStack* _mark_stack; 1811 CMSBitMap* _bit_map; 1812 CMSKeepAliveClosure* _keep_alive; 1813 bool _concurrent_precleaning; 1814 public: 1815 CMSDrainMarkingStackClosure(CMSCollector* collector, MemRegion span, 1816 CMSBitMap* bit_map, CMSMarkStack* mark_stack, 1817 CMSKeepAliveClosure* keep_alive, 1818 bool cpc): 1819 _collector(collector), 1820 _span(span), 1821 _bit_map(bit_map), 1822 _mark_stack(mark_stack), 1823 _keep_alive(keep_alive), 1824 _concurrent_precleaning(cpc) { 1825 assert(_concurrent_precleaning == _keep_alive->concurrent_precleaning(), 1826 "Mismatch"); 1827 } 1828 1829 void do_void(); 1830 }; 1831 1832 // A parallel version of CMSDrainMarkingStackClosure above. 1833 class CMSParDrainMarkingStackClosure: public VoidClosure { 1834 CMSCollector* _collector; 1835 MemRegion _span; 1836 OopTaskQueue* _work_queue; 1837 CMSBitMap* _bit_map; 1838 CMSInnerParMarkAndPushClosure _mark_and_push; 1839 1840 public: 1841 CMSParDrainMarkingStackClosure(CMSCollector* collector, 1842 MemRegion span, CMSBitMap* bit_map, 1843 OopTaskQueue* work_queue): 1844 _collector(collector), 1845 _span(span), 1846 _bit_map(bit_map), 1847 _work_queue(work_queue), 1848 _mark_and_push(collector, span, bit_map, work_queue) { } 1849 1850 public: 1851 void trim_queue(uint max); 1852 void do_void(); 1853 }; 1854 1855 // Allow yielding or short-circuiting of reference list 1856 // prelceaning work. 1857 class CMSPrecleanRefsYieldClosure: public YieldClosure { 1858 CMSCollector* _collector; 1859 void do_yield_work(); 1860 public: 1861 CMSPrecleanRefsYieldClosure(CMSCollector* collector): 1862 _collector(collector) {} 1863 virtual bool should_return(); 1864 }; 1865 1866 1867 // Convenience class that locks free list locks for given CMS collector 1868 class FreelistLocker: public StackObj { 1869 private: 1870 CMSCollector* _collector; 1871 public: 1872 FreelistLocker(CMSCollector* collector): 1873 _collector(collector) { 1874 _collector->getFreelistLocks(); 1875 } 1876 1877 ~FreelistLocker() { 1878 _collector->releaseFreelistLocks(); 1879 } 1880 }; 1881 1882 // Mark all dead objects in a given space. 1883 class MarkDeadObjectsClosure: public BlkClosure { 1884 const CMSCollector* _collector; 1885 const CompactibleFreeListSpace* _sp; 1886 CMSBitMap* _live_bit_map; 1887 CMSBitMap* _dead_bit_map; 1888 public: 1889 MarkDeadObjectsClosure(const CMSCollector* collector, 1890 const CompactibleFreeListSpace* sp, 1891 CMSBitMap *live_bit_map, 1892 CMSBitMap *dead_bit_map) : 1893 _collector(collector), 1894 _sp(sp), 1895 _live_bit_map(live_bit_map), 1896 _dead_bit_map(dead_bit_map) {} 1897 size_t do_blk(HeapWord* addr); 1898 }; 1899 1900 class TraceCMSMemoryManagerStats : public TraceMemoryManagerStats { 1901 1902 public: 1903 TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause); 1904 }; 1905 1906 1907 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CONCURRENTMARKSWEEPGENERATION_HPP