Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp @ 143:b5489bb705c9
6662086: 6u4+, 7b11+: CMS never clears referents when -XX:+ParallelRefProcEnabled
Summary: Construct the relevant CMSIsAliveClosure used by CMS during parallel reference processing with the correct span. It had incorrectly been constructed with an empty span, a regression introduced in 6417901.
Reviewed-by: jcoomes
| author | ysr |
|---|---|
| date | Tue, 06 May 2008 15:37:36 -0700 |
| parents | ba764ed4b6f2 |
| children | d1605aabd0a1 37f87013dfd8 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 // ConcurrentMarkSweepGeneration is in support of a concurrent | |
| 26 // mark-sweep old generation in the Detlefs-Printezis--Boehm-Demers-Schenker | |
| 27 // style. We assume, for now, that this generation is always the | |
| 28 // seniormost generation (modulo the PermGeneration), and for simplicity | |
| 29 // in the first implementation, that this generation is a single compactible | |
| 30 // space. Neither of these restrictions appears essential, and will be | |
| 31 // relaxed in the future when more time is available to implement the | |
| 32 // greater generality (and there's a need for it). | |
| 33 // | |
| 34 // Concurrent mode failures are currently handled by | |
| 35 // means of a sliding mark-compact. | |
| 36 | |
| 37 class CMSAdaptiveSizePolicy; | |
| 38 class CMSConcMarkingTask; | |
| 39 class CMSGCAdaptivePolicyCounters; | |
| 40 class ConcurrentMarkSweepGeneration; | |
| 41 class ConcurrentMarkSweepPolicy; | |
| 42 class ConcurrentMarkSweepThread; | |
| 43 class CompactibleFreeListSpace; | |
| 44 class FreeChunk; | |
| 45 class PromotionInfo; | |
| 46 class ScanMarkedObjectsAgainCarefullyClosure; | |
| 47 | |
| 48 // A generic CMS bit map. It's the basis for both the CMS marking bit map | |
| 49 // as well as for the mod union table (in each case only a subset of the | |
| 50 // methods are used). This is essentially a wrapper around the BitMap class, | |
| 51 // with one bit per (1<<_shifter) HeapWords. (i.e. for the marking bit map, | |
| 52 // we have _shifter == 0. and for the mod union table we have | |
| 53 // shifter == CardTableModRefBS::card_shift - LogHeapWordSize.) | |
| 54 // XXX 64-bit issues in BitMap? | |
| 55 class CMSBitMap VALUE_OBJ_CLASS_SPEC { | |
| 56 friend class VMStructs; | |
| 57 | |
| 58 HeapWord* _bmStartWord; // base address of range covered by map | |
| 59 size_t _bmWordSize; // map size (in #HeapWords covered) | |
| 60 const int _shifter; // shifts to convert HeapWord to bit position | |
| 61 VirtualSpace _virtual_space; // underlying the bit map | |
| 62 BitMap _bm; // the bit map itself | |
| 63 public: | |
| 64 Mutex* const _lock; // mutex protecting _bm; | |
| 65 | |
| 66 public: | |
| 67 // constructor | |
| 68 CMSBitMap(int shifter, int mutex_rank, const char* mutex_name); | |
| 69 | |
| 70 // allocates the actual storage for the map | |
| 71 bool allocate(MemRegion mr); | |
| 72 // field getter | |
| 73 Mutex* lock() const { return _lock; } | |
| 74 // locking verifier convenience function | |
| 75 void assert_locked() const PRODUCT_RETURN; | |
| 76 | |
| 77 // inquiries | |
| 78 HeapWord* startWord() const { return _bmStartWord; } | |
| 79 size_t sizeInWords() const { return _bmWordSize; } | |
| 80 size_t sizeInBits() const { return _bm.size(); } | |
| 81 // the following is one past the last word in space | |
| 82 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; } | |
| 83 | |
| 84 // reading marks | |
| 85 bool isMarked(HeapWord* addr) const; | |
| 86 bool par_isMarked(HeapWord* addr) const; // do not lock checks | |
| 87 bool isUnmarked(HeapWord* addr) const; | |
| 88 bool isAllClear() const; | |
| 89 | |
| 90 // writing marks | |
| 91 void mark(HeapWord* addr); | |
| 92 // For marking by parallel GC threads; | |
| 93 // returns true if we did, false if another thread did | |
| 94 bool par_mark(HeapWord* addr); | |
| 95 | |
| 96 void mark_range(MemRegion mr); | |
| 97 void par_mark_range(MemRegion mr); | |
| 98 void mark_large_range(MemRegion mr); | |
| 99 void par_mark_large_range(MemRegion mr); | |
| 100 void par_clear(HeapWord* addr); // For unmarking by parallel GC threads. | |
| 101 void clear_range(MemRegion mr); | |
| 102 void par_clear_range(MemRegion mr); | |
| 103 void clear_large_range(MemRegion mr); | |
| 104 void par_clear_large_range(MemRegion mr); | |
| 105 void clear_all(); | |
| 106 void clear_all_incrementally(); // Not yet implemented!! | |
| 107 | |
| 108 NOT_PRODUCT( | |
| 109 // checks the memory region for validity | |
| 110 void region_invariant(MemRegion mr); | |
| 111 ) | |
| 112 | |
| 113 // iteration | |
| 114 void iterate(BitMapClosure* cl) { | |
| 115 _bm.iterate(cl); | |
| 116 } | |
| 117 void iterate(BitMapClosure* cl, HeapWord* left, HeapWord* right); | |
| 118 void dirty_range_iterate_clear(MemRegionClosure* cl); | |
| 119 void dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl); | |
| 120 | |
| 121 // auxiliary support for iteration | |
| 122 HeapWord* getNextMarkedWordAddress(HeapWord* addr) const; | |
| 123 HeapWord* getNextMarkedWordAddress(HeapWord* start_addr, | |
| 124 HeapWord* end_addr) const; | |
| 125 HeapWord* getNextUnmarkedWordAddress(HeapWord* addr) const; | |
| 126 HeapWord* getNextUnmarkedWordAddress(HeapWord* start_addr, | |
| 127 HeapWord* end_addr) const; | |
| 128 MemRegion getAndClearMarkedRegion(HeapWord* addr); | |
| 129 MemRegion getAndClearMarkedRegion(HeapWord* start_addr, | |
| 130 HeapWord* end_addr); | |
| 131 | |
| 132 // conversion utilities | |
| 133 HeapWord* offsetToHeapWord(size_t offset) const; | |
| 134 size_t heapWordToOffset(HeapWord* addr) const; | |
| 135 size_t heapWordDiffToOffsetDiff(size_t diff) const; | |
| 136 | |
| 137 // debugging | |
| 138 // is this address range covered by the bit-map? | |
| 139 NOT_PRODUCT( | |
| 140 bool covers(MemRegion mr) const; | |
| 141 bool covers(HeapWord* start, size_t size = 0) const; | |
| 142 ) | |
| 143 void verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) PRODUCT_RETURN; | |
| 144 }; | |
| 145 | |
| 146 // Represents a marking stack used by the CMS collector. | |
| 147 // Ideally this should be GrowableArray<> just like MSC's marking stack(s). | |
| 148 class CMSMarkStack: public CHeapObj { | |
| 149 // | |
| 150 friend class CMSCollector; // to get at expasion stats further below | |
| 151 // | |
| 152 | |
| 153 VirtualSpace _virtual_space; // space for the stack | |
| 154 oop* _base; // bottom of stack | |
| 155 size_t _index; // one more than last occupied index | |
| 156 size_t _capacity; // max #elements | |
| 157 Mutex _par_lock; // an advisory lock used in case of parallel access | |
| 158 NOT_PRODUCT(size_t _max_depth;) // max depth plumbed during run | |
| 159 | |
| 160 protected: | |
| 161 size_t _hit_limit; // we hit max stack size limit | |
| 162 size_t _failed_double; // we failed expansion before hitting limit | |
| 163 | |
| 164 public: | |
| 165 CMSMarkStack(): | |
| 166 _par_lock(Mutex::event, "CMSMarkStack._par_lock", true), | |
| 167 _hit_limit(0), | |
| 168 _failed_double(0) {} | |
| 169 | |
| 170 bool allocate(size_t size); | |
| 171 | |
| 172 size_t capacity() const { return _capacity; } | |
| 173 | |
| 174 oop pop() { | |
| 175 if (!isEmpty()) { | |
| 176 return _base[--_index] ; | |
| 177 } | |
| 178 return NULL; | |
| 179 } | |
| 180 | |
| 181 bool push(oop ptr) { | |
| 182 if (isFull()) { | |
| 183 return false; | |
| 184 } else { | |
| 185 _base[_index++] = ptr; | |
| 186 NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index)); | |
| 187 return true; | |
| 188 } | |
| 189 } | |
| 190 | |
| 191 bool isEmpty() const { return _index == 0; } | |
| 192 bool isFull() const { | |
| 193 assert(_index <= _capacity, "buffer overflow"); | |
| 194 return _index == _capacity; | |
| 195 } | |
| 196 | |
| 197 size_t length() { return _index; } | |
| 198 | |
| 199 // "Parallel versions" of some of the above | |
| 200 oop par_pop() { | |
| 201 // lock and pop | |
| 202 MutexLockerEx x(&_par_lock, Mutex::_no_safepoint_check_flag); | |
| 203 return pop(); | |
| 204 } | |
| 205 | |
| 206 bool par_push(oop ptr) { | |
| 207 // lock and push | |
| 208 MutexLockerEx x(&_par_lock, Mutex::_no_safepoint_check_flag); | |
| 209 return push(ptr); | |
| 210 } | |
| 211 | |
| 212 // Forcibly reset the stack, losing all of its contents. | |
| 213 void reset() { | |
| 214 _index = 0; | |
| 215 } | |
| 216 | |
| 217 // Expand the stack, typically in response to an overflow condition | |
| 218 void expand(); | |
| 219 | |
| 220 // Compute the least valued stack element. | |
| 221 oop least_value(HeapWord* low) { | |
| 222 oop least = (oop)low; | |
| 223 for (size_t i = 0; i < _index; i++) { | |
| 224 least = MIN2(least, _base[i]); | |
| 225 } | |
| 226 return least; | |
| 227 } | |
| 228 | |
| 229 // Exposed here to allow stack expansion in || case | |
| 230 Mutex* par_lock() { return &_par_lock; } | |
| 231 }; | |
| 232 | |
| 233 class CardTableRS; | |
| 234 class CMSParGCThreadState; | |
| 235 | |
| 236 class ModUnionClosure: public MemRegionClosure { | |
| 237 protected: | |
| 238 CMSBitMap* _t; | |
| 239 public: | |
| 240 ModUnionClosure(CMSBitMap* t): _t(t) { } | |
| 241 void do_MemRegion(MemRegion mr); | |
| 242 }; | |
| 243 | |
| 244 class ModUnionClosurePar: public ModUnionClosure { | |
| 245 public: | |
| 246 ModUnionClosurePar(CMSBitMap* t): ModUnionClosure(t) { } | |
| 247 void do_MemRegion(MemRegion mr); | |
| 248 }; | |
| 249 | |
| 250 // Survivor Chunk Array in support of parallelization of | |
| 251 // Survivor Space rescan. | |
| 252 class ChunkArray: public CHeapObj { | |
| 253 size_t _index; | |
| 254 size_t _capacity; | |
| 255 HeapWord** _array; // storage for array | |
| 256 | |
| 257 public: | |
| 258 ChunkArray() : _index(0), _capacity(0), _array(NULL) {} | |
| 259 ChunkArray(HeapWord** a, size_t c): | |
| 260 _index(0), _capacity(c), _array(a) {} | |
| 261 | |
| 262 HeapWord** array() { return _array; } | |
| 263 void set_array(HeapWord** a) { _array = a; } | |
| 264 | |
| 265 size_t capacity() { return _capacity; } | |
| 266 void set_capacity(size_t c) { _capacity = c; } | |
| 267 | |
| 268 size_t end() { | |
| 269 assert(_index < capacity(), "_index out of bounds"); | |
| 270 return _index; | |
| 271 } // exclusive | |
| 272 | |
| 273 HeapWord* nth(size_t n) { | |
| 274 assert(n < end(), "Out of bounds access"); | |
| 275 return _array[n]; | |
| 276 } | |
| 277 | |
| 278 void reset() { | |
| 279 _index = 0; | |
| 280 } | |
| 281 | |
| 282 void record_sample(HeapWord* p, size_t sz) { | |
| 283 // For now we do not do anything with the size | |
| 284 if (_index < _capacity) { | |
| 285 _array[_index++] = p; | |
| 286 } | |
| 287 } | |
| 288 }; | |
| 289 | |
| 290 // | |
| 291 // Timing, allocation and promotion statistics for gc scheduling and incremental | |
| 292 // mode pacing. Most statistics are exponential averages. | |
| 293 // | |
| 294 class CMSStats VALUE_OBJ_CLASS_SPEC { | |
| 295 private: | |
| 296 ConcurrentMarkSweepGeneration* const _cms_gen; // The cms (old) gen. | |
| 297 | |
| 298 // The following are exponential averages with factor alpha: | |
| 299 // avg = (100 - alpha) * avg + alpha * cur_sample | |
| 300 // | |
| 301 // The durations measure: end_time[n] - start_time[n] | |
| 302 // The periods measure: start_time[n] - start_time[n-1] | |
| 303 // | |
| 304 // The cms period and duration include only concurrent collections; time spent | |
| 305 // in foreground cms collections due to System.gc() or because of a failure to | |
| 306 // keep up are not included. | |
| 307 // | |
| 308 // There are 3 alphas to "bootstrap" the statistics. The _saved_alpha is the | |
| 309 // real value, but is used only after the first period. A value of 100 is | |
| 310 // used for the first sample so it gets the entire weight. | |
| 311 unsigned int _saved_alpha; // 0-100 | |
| 312 unsigned int _gc0_alpha; | |
| 313 unsigned int _cms_alpha; | |
| 314 | |
| 315 double _gc0_duration; | |
| 316 double _gc0_period; | |
| 317 size_t _gc0_promoted; // bytes promoted per gc0 | |
| 318 double _cms_duration; | |
| 319 double _cms_duration_pre_sweep; // time from initiation to start of sweep | |
| 320 double _cms_duration_per_mb; | |
| 321 double _cms_period; | |
| 322 size_t _cms_allocated; // bytes of direct allocation per gc0 period | |
| 323 | |
| 324 // Timers. | |
| 325 elapsedTimer _cms_timer; | |
| 326 TimeStamp _gc0_begin_time; | |
| 327 TimeStamp _cms_begin_time; | |
| 328 TimeStamp _cms_end_time; | |
| 329 | |
| 330 // Snapshots of the amount used in the CMS generation. | |
| 331 size_t _cms_used_at_gc0_begin; | |
| 332 size_t _cms_used_at_gc0_end; | |
| 333 size_t _cms_used_at_cms_begin; | |
| 334 | |
| 335 // Used to prevent the duty cycle from being reduced in the middle of a cms | |
| 336 // cycle. | |
| 337 bool _allow_duty_cycle_reduction; | |
| 338 | |
| 339 enum { | |
| 340 _GC0_VALID = 0x1, | |
| 341 _CMS_VALID = 0x2, | |
| 342 _ALL_VALID = _GC0_VALID | _CMS_VALID | |
| 343 }; | |
| 344 | |
| 345 unsigned int _valid_bits; | |
| 346 | |
| 347 unsigned int _icms_duty_cycle; // icms duty cycle (0-100). | |
| 348 | |
| 349 protected: | |
| 350 | |
| 351 // Return a duty cycle that avoids wild oscillations, by limiting the amount | |
| 352 // of change between old_duty_cycle and new_duty_cycle (the latter is treated | |
| 353 // as a recommended value). | |
| 354 static unsigned int icms_damped_duty_cycle(unsigned int old_duty_cycle, | |
| 355 unsigned int new_duty_cycle); | |
| 356 unsigned int icms_update_duty_cycle_impl(); | |
| 357 | |
| 358 public: | |
| 359 CMSStats(ConcurrentMarkSweepGeneration* cms_gen, | |
| 360 unsigned int alpha = CMSExpAvgFactor); | |
| 361 | |
| 362 // Whether or not the statistics contain valid data; higher level statistics | |
| 363 // cannot be called until this returns true (they require at least one young | |
| 364 // gen and one cms cycle to have completed). | |
| 365 bool valid() const; | |
| 366 | |
| 367 // Record statistics. | |
| 368 void record_gc0_begin(); | |
| 369 void record_gc0_end(size_t cms_gen_bytes_used); | |
| 370 void record_cms_begin(); | |
| 371 void record_cms_end(); | |
| 372 | |
| 373 // Allow management of the cms timer, which must be stopped/started around | |
| 374 // yield points. | |
| 375 elapsedTimer& cms_timer() { return _cms_timer; } | |
| 376 void start_cms_timer() { _cms_timer.start(); } | |
| 377 void stop_cms_timer() { _cms_timer.stop(); } | |
| 378 | |
| 379 // Basic statistics; units are seconds or bytes. | |
| 380 double gc0_period() const { return _gc0_period; } | |
| 381 double gc0_duration() const { return _gc0_duration; } | |
| 382 size_t gc0_promoted() const { return _gc0_promoted; } | |
| 383 double cms_period() const { return _cms_period; } | |
| 384 double cms_duration() const { return _cms_duration; } | |
| 385 double cms_duration_per_mb() const { return _cms_duration_per_mb; } | |
| 386 size_t cms_allocated() const { return _cms_allocated; } | |
| 387 | |
| 388 size_t cms_used_at_gc0_end() const { return _cms_used_at_gc0_end;} | |
| 389 | |
| 390 // Seconds since the last background cms cycle began or ended. | |
| 391 double cms_time_since_begin() const; | |
| 392 double cms_time_since_end() const; | |
| 393 | |
| 394 // Higher level statistics--caller must check that valid() returns true before | |
| 395 // calling. | |
| 396 | |
| 397 // Returns bytes promoted per second of wall clock time. | |
| 398 double promotion_rate() const; | |
| 399 | |
| 400 // Returns bytes directly allocated per second of wall clock time. | |
| 401 double cms_allocation_rate() const; | |
| 402 | |
| 403 // Rate at which space in the cms generation is being consumed (sum of the | |
| 404 // above two). | |
| 405 double cms_consumption_rate() const; | |
| 406 | |
| 407 // Returns an estimate of the number of seconds until the cms generation will | |
| 408 // fill up, assuming no collection work is done. | |
| 409 double time_until_cms_gen_full() const; | |
| 410 | |
| 411 // Returns an estimate of the number of seconds remaining until | |
| 412 // the cms generation collection should start. | |
| 413 double time_until_cms_start() const; | |
| 414 | |
| 415 // End of higher level statistics. | |
| 416 | |
| 417 // Returns the cms incremental mode duty cycle, as a percentage (0-100). | |
| 418 unsigned int icms_duty_cycle() const { return _icms_duty_cycle; } | |
| 419 | |
| 420 // Update the duty cycle and return the new value. | |
| 421 unsigned int icms_update_duty_cycle(); | |
| 422 | |
| 423 // Debugging. | |
| 424 void print_on(outputStream* st) const PRODUCT_RETURN; | |
| 425 void print() const { print_on(gclog_or_tty); } | |
| 426 }; | |
| 427 | |
| 428 // A closure related to weak references processing which | |
| 429 // we embed in the CMSCollector, since we need to pass | |
| 430 // it to the reference processor for secondary filtering | |
| 431 // of references based on reachability of referent; | |
| 432 // see role of _is_alive_non_header closure in the | |
| 433 // ReferenceProcessor class. | |
| 434 // For objects in the CMS generation, this closure checks | |
| 435 // if the object is "live" (reachable). Used in weak | |
| 436 // reference processing. | |
| 437 class CMSIsAliveClosure: public BoolObjectClosure { | |
|
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438 const MemRegion _span; |
| 0 | 439 const CMSBitMap* _bit_map; |
| 440 | |
| 441 friend class CMSCollector; | |
| 442 public: | |
| 443 CMSIsAliveClosure(MemRegion span, | |
| 444 CMSBitMap* bit_map): | |
| 445 _span(span), | |
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446 _bit_map(bit_map) { |
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447 assert(!span.is_empty(), "Empty span could spell trouble"); |
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448 } |
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449 |
| 0 | 450 void do_object(oop obj) { |
| 451 assert(false, "not to be invoked"); | |
| 452 } | |
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453 |
| 0 | 454 bool do_object_b(oop obj); |
| 455 }; | |
| 456 | |
| 457 | |
| 458 // Implements AbstractRefProcTaskExecutor for CMS. | |
| 459 class CMSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { | |
| 460 public: | |
| 461 | |
| 462 CMSRefProcTaskExecutor(CMSCollector& collector) | |
| 463 : _collector(collector) | |
| 464 { } | |
| 465 | |
| 466 // Executes a task using worker threads. | |
| 467 virtual void execute(ProcessTask& task); | |
| 468 virtual void execute(EnqueueTask& task); | |
| 469 private: | |
| 470 CMSCollector& _collector; | |
| 471 }; | |
| 472 | |
| 473 | |
| 474 class CMSCollector: public CHeapObj { | |
| 475 friend class VMStructs; | |
| 476 friend class ConcurrentMarkSweepThread; | |
| 477 friend class ConcurrentMarkSweepGeneration; | |
| 478 friend class CompactibleFreeListSpace; | |
| 479 friend class CMSParRemarkTask; | |
| 480 friend class CMSConcMarkingTask; | |
| 481 friend class CMSRefProcTaskProxy; | |
| 482 friend class CMSRefProcTaskExecutor; | |
| 483 friend class ScanMarkedObjectsAgainCarefullyClosure; // for sampling eden | |
| 484 friend class SurvivorSpacePrecleanClosure; // --- ditto ------- | |
| 485 friend class PushOrMarkClosure; // to access _restart_addr | |
| 486 friend class Par_PushOrMarkClosure; // to access _restart_addr | |
| 487 friend class MarkFromRootsClosure; // -- ditto -- | |
| 488 // ... and for clearing cards | |
| 489 friend class Par_MarkFromRootsClosure; // to access _restart_addr | |
| 490 // ... and for clearing cards | |
| 491 friend class Par_ConcMarkingClosure; // to access _restart_addr etc. | |
| 492 friend class MarkFromRootsVerifyClosure; // to access _restart_addr | |
| 493 friend class PushAndMarkVerifyClosure; // -- ditto -- | |
| 494 friend class MarkRefsIntoAndScanClosure; // to access _overflow_list | |
| 495 friend class PushAndMarkClosure; // -- ditto -- | |
| 496 friend class Par_PushAndMarkClosure; // -- ditto -- | |
| 497 friend class CMSKeepAliveClosure; // -- ditto -- | |
| 498 friend class CMSDrainMarkingStackClosure; // -- ditto -- | |
| 499 friend class CMSInnerParMarkAndPushClosure; // -- ditto -- | |
| 500 NOT_PRODUCT(friend class ScanMarkedObjectsAgainClosure;) // assertion on _overflow_list | |
| 501 friend class ReleaseForegroundGC; // to access _foregroundGCShouldWait | |
| 502 friend class VM_CMS_Operation; | |
| 503 friend class VM_CMS_Initial_Mark; | |
| 504 friend class VM_CMS_Final_Remark; | |
| 505 | |
| 506 private: | |
| 507 jlong _time_of_last_gc; | |
| 508 void update_time_of_last_gc(jlong now) { | |
| 509 _time_of_last_gc = now; | |
| 510 } | |
| 511 | |
| 512 OopTaskQueueSet* _task_queues; | |
| 513 | |
| 514 // Overflow list of grey objects, threaded through mark-word | |
| 515 // Manipulated with CAS in the parallel/multi-threaded case. | |
| 516 oop _overflow_list; | |
| 517 // The following array-pair keeps track of mark words | |
| 518 // displaced for accomodating overflow list above. | |
| 519 // This code will likely be revisited under RFE#4922830. | |
| 520 GrowableArray<oop>* _preserved_oop_stack; | |
| 521 GrowableArray<markOop>* _preserved_mark_stack; | |
| 522 | |
| 523 int* _hash_seed; | |
| 524 | |
| 525 // In support of multi-threaded concurrent phases | |
| 526 YieldingFlexibleWorkGang* _conc_workers; | |
| 527 | |
| 528 // Performance Counters | |
| 529 CollectorCounters* _gc_counters; | |
| 530 | |
| 531 // Initialization Errors | |
| 532 bool _completed_initialization; | |
| 533 | |
| 534 // In support of ExplicitGCInvokesConcurrent | |
| 535 static bool _full_gc_requested; | |
| 536 unsigned int _collection_count_start; | |
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537 |
| 0 | 538 // Should we unload classes this concurrent cycle? |
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539 bool _should_unload_classes; |
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540 unsigned int _concurrent_cycles_since_last_unload; |
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541 unsigned int concurrent_cycles_since_last_unload() const { |
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542 return _concurrent_cycles_since_last_unload; |
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543 } |
| 0 | 544 // Did we (allow) unload classes in the previous concurrent cycle? |
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545 bool unloaded_classes_last_cycle() const { |
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546 return concurrent_cycles_since_last_unload() == 0; |
| 0 | 547 } |
| 548 | |
| 549 // Verification support | |
| 550 CMSBitMap _verification_mark_bm; | |
| 551 void verify_after_remark_work_1(); | |
| 552 void verify_after_remark_work_2(); | |
| 553 | |
| 554 // true if any verification flag is on. | |
| 555 bool _verifying; | |
| 556 bool verifying() const { return _verifying; } | |
| 557 void set_verifying(bool v) { _verifying = v; } | |
| 558 | |
| 559 // Collector policy | |
| 560 ConcurrentMarkSweepPolicy* _collector_policy; | |
| 561 ConcurrentMarkSweepPolicy* collector_policy() { return _collector_policy; } | |
| 562 | |
| 563 // Check whether the gc time limit has been | |
| 564 // exceeded and set the size policy flag | |
| 565 // appropriately. | |
| 566 void check_gc_time_limit(); | |
| 567 // XXX Move these to CMSStats ??? FIX ME !!! | |
| 568 elapsedTimer _sweep_timer; | |
| 569 AdaptivePaddedAverage _sweep_estimate; | |
| 570 | |
| 571 protected: | |
| 572 ConcurrentMarkSweepGeneration* _cmsGen; // old gen (CMS) | |
| 573 ConcurrentMarkSweepGeneration* _permGen; // perm gen | |
| 574 MemRegion _span; // span covering above two | |
| 575 CardTableRS* _ct; // card table | |
| 576 | |
| 577 // CMS marking support structures | |
| 578 CMSBitMap _markBitMap; | |
| 579 CMSBitMap _modUnionTable; | |
| 580 CMSMarkStack _markStack; | |
| 581 CMSMarkStack _revisitStack; // used to keep track of klassKlass objects | |
| 582 // to revisit | |
| 583 CMSBitMap _perm_gen_verify_bit_map; // Mark bit map for perm gen verification support. | |
| 584 | |
| 585 HeapWord* _restart_addr; // in support of marking stack overflow | |
| 586 void lower_restart_addr(HeapWord* low); | |
| 587 | |
| 588 // Counters in support of marking stack / work queue overflow handling: | |
| 589 // a non-zero value indicates certain types of overflow events during | |
| 590 // the current CMS cycle and could lead to stack resizing efforts at | |
| 591 // an opportune future time. | |
| 592 size_t _ser_pmc_preclean_ovflw; | |
| 593 size_t _ser_pmc_remark_ovflw; | |
| 594 size_t _par_pmc_remark_ovflw; | |
| 595 size_t _ser_kac_ovflw; | |
| 596 size_t _par_kac_ovflw; | |
| 597 NOT_PRODUCT(size_t _num_par_pushes;) | |
| 598 | |
| 599 // ("Weak") Reference processing support | |
| 600 ReferenceProcessor* _ref_processor; | |
| 601 CMSIsAliveClosure _is_alive_closure; | |
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602 // keep this textually after _markBitMap and _span; c'tor dependency |
| 0 | 603 |
| 604 ConcurrentMarkSweepThread* _cmsThread; // the thread doing the work | |
| 605 ModUnionClosure _modUnionClosure; | |
| 606 ModUnionClosurePar _modUnionClosurePar; | |
| 607 | |
| 608 // CMS abstract state machine | |
| 609 // initial_state: Idling | |
| 610 // next_state(Idling) = {Marking} | |
| 611 // next_state(Marking) = {Precleaning, Sweeping} | |
| 612 // next_state(Precleaning) = {AbortablePreclean, FinalMarking} | |
| 613 // next_state(AbortablePreclean) = {FinalMarking} | |
| 614 // next_state(FinalMarking) = {Sweeping} | |
| 615 // next_state(Sweeping) = {Resizing} | |
| 616 // next_state(Resizing) = {Resetting} | |
| 617 // next_state(Resetting) = {Idling} | |
| 618 // The numeric values below are chosen so that: | |
| 619 // . _collectorState <= Idling == post-sweep && pre-mark | |
| 620 // . _collectorState in (Idling, Sweeping) == {initial,final}marking || | |
| 621 // precleaning || abortablePrecleanb | |
| 622 enum CollectorState { | |
| 623 Resizing = 0, | |
| 624 Resetting = 1, | |
| 625 Idling = 2, | |
| 626 InitialMarking = 3, | |
| 627 Marking = 4, | |
| 628 Precleaning = 5, | |
| 629 AbortablePreclean = 6, | |
| 630 FinalMarking = 7, | |
| 631 Sweeping = 8 | |
| 632 }; | |
| 633 static CollectorState _collectorState; | |
| 634 | |
| 635 // State related to prologue/epilogue invocation for my generations | |
| 636 bool _between_prologue_and_epilogue; | |
| 637 | |
| 638 // Signalling/State related to coordination between fore- and backgroud GC | |
| 639 // Note: When the baton has been passed from background GC to foreground GC, | |
| 640 // _foregroundGCIsActive is true and _foregroundGCShouldWait is false. | |
| 641 static bool _foregroundGCIsActive; // true iff foreground collector is active or | |
| 642 // wants to go active | |
| 643 static bool _foregroundGCShouldWait; // true iff background GC is active and has not | |
| 644 // yet passed the baton to the foreground GC | |
| 645 | |
| 646 // Support for CMSScheduleRemark (abortable preclean) | |
| 647 bool _abort_preclean; | |
| 648 bool _start_sampling; | |
| 649 | |
| 650 int _numYields; | |
| 651 size_t _numDirtyCards; | |
| 652 uint _sweepCount; | |
| 653 // number of full gc's since the last concurrent gc. | |
| 654 uint _full_gcs_since_conc_gc; | |
| 655 | |
| 656 // occupancy used for bootstrapping stats | |
| 657 double _bootstrap_occupancy; | |
| 658 | |
| 659 // timer | |
| 660 elapsedTimer _timer; | |
| 661 | |
| 662 // Timing, allocation and promotion statistics, used for scheduling. | |
| 663 CMSStats _stats; | |
| 664 | |
| 665 // Allocation limits installed in the young gen, used only in | |
| 666 // CMSIncrementalMode. When an allocation in the young gen would cross one of | |
| 667 // these limits, the cms generation is notified and the cms thread is started | |
| 668 // or stopped, respectively. | |
| 669 HeapWord* _icms_start_limit; | |
| 670 HeapWord* _icms_stop_limit; | |
| 671 | |
| 672 enum CMS_op_type { | |
| 673 CMS_op_checkpointRootsInitial, | |
| 674 CMS_op_checkpointRootsFinal | |
| 675 }; | |
| 676 | |
| 677 void do_CMS_operation(CMS_op_type op); | |
| 678 bool stop_world_and_do(CMS_op_type op); | |
| 679 | |
| 680 OopTaskQueueSet* task_queues() { return _task_queues; } | |
| 681 int* hash_seed(int i) { return &_hash_seed[i]; } | |
| 682 YieldingFlexibleWorkGang* conc_workers() { return _conc_workers; } | |
| 683 | |
| 684 // Support for parallelizing Eden rescan in CMS remark phase | |
| 685 void sample_eden(); // ... sample Eden space top | |
| 686 | |
| 687 private: | |
| 688 // Support for parallelizing young gen rescan in CMS remark phase | |
| 689 Generation* _young_gen; // the younger gen | |
| 690 HeapWord** _top_addr; // ... Top of Eden | |
| 691 HeapWord** _end_addr; // ... End of Eden | |
| 692 HeapWord** _eden_chunk_array; // ... Eden partitioning array | |
| 693 size_t _eden_chunk_index; // ... top (exclusive) of array | |
| 694 size_t _eden_chunk_capacity; // ... max entries in array | |
| 695 | |
| 696 // Support for parallelizing survivor space rescan | |
| 697 HeapWord** _survivor_chunk_array; | |
| 698 size_t _survivor_chunk_index; | |
| 699 size_t _survivor_chunk_capacity; | |
| 700 size_t* _cursor; | |
| 701 ChunkArray* _survivor_plab_array; | |
| 702 | |
| 703 // Support for marking stack overflow handling | |
| 704 bool take_from_overflow_list(size_t num, CMSMarkStack* to_stack); | |
| 705 bool par_take_from_overflow_list(size_t num, OopTaskQueue* to_work_q); | |
| 706 void push_on_overflow_list(oop p); | |
| 707 void par_push_on_overflow_list(oop p); | |
| 708 // the following is, obviously, not, in general, "MT-stable" | |
| 709 bool overflow_list_is_empty() const; | |
| 710 | |
| 711 void preserve_mark_if_necessary(oop p); | |
| 712 void par_preserve_mark_if_necessary(oop p); | |
| 713 void preserve_mark_work(oop p, markOop m); | |
| 714 void restore_preserved_marks_if_any(); | |
| 715 NOT_PRODUCT(bool no_preserved_marks() const;) | |
| 716 // in support of testing overflow code | |
| 717 NOT_PRODUCT(int _overflow_counter;) | |
| 718 NOT_PRODUCT(bool simulate_overflow();) // sequential | |
| 719 NOT_PRODUCT(bool par_simulate_overflow();) // MT version | |
| 720 | |
| 721 int _roots_scanning_options; | |
| 722 int roots_scanning_options() const { return _roots_scanning_options; } | |
| 723 void add_root_scanning_option(int o) { _roots_scanning_options |= o; } | |
| 724 void remove_root_scanning_option(int o) { _roots_scanning_options &= ~o; } | |
| 725 | |
| 726 // CMS work methods | |
| 727 void checkpointRootsInitialWork(bool asynch); // initial checkpoint work | |
| 728 | |
| 729 // a return value of false indicates failure due to stack overflow | |
| 730 bool markFromRootsWork(bool asynch); // concurrent marking work | |
| 731 | |
| 732 public: // FIX ME!!! only for testing | |
| 733 bool do_marking_st(bool asynch); // single-threaded marking | |
| 734 bool do_marking_mt(bool asynch); // multi-threaded marking | |
| 735 | |
| 736 private: | |
| 737 | |
| 738 // concurrent precleaning work | |
| 739 size_t preclean_mod_union_table(ConcurrentMarkSweepGeneration* gen, | |
| 740 ScanMarkedObjectsAgainCarefullyClosure* cl); | |
| 741 size_t preclean_card_table(ConcurrentMarkSweepGeneration* gen, | |
| 742 ScanMarkedObjectsAgainCarefullyClosure* cl); | |
| 743 // Does precleaning work, returning a quantity indicative of | |
| 744 // the amount of "useful work" done. | |
| 745 size_t preclean_work(bool clean_refs, bool clean_survivors); | |
| 746 void abortable_preclean(); // Preclean while looking for possible abort | |
| 747 void initialize_sequential_subtasks_for_young_gen_rescan(int i); | |
| 748 // Helper function for above; merge-sorts the per-thread plab samples | |
| 749 void merge_survivor_plab_arrays(ContiguousSpace* surv); | |
| 750 // Resets (i.e. clears) the per-thread plab sample vectors | |
| 751 void reset_survivor_plab_arrays(); | |
| 752 | |
| 753 // final (second) checkpoint work | |
| 754 void checkpointRootsFinalWork(bool asynch, bool clear_all_soft_refs, | |
| 755 bool init_mark_was_synchronous); | |
| 756 // work routine for parallel version of remark | |
| 757 void do_remark_parallel(); | |
| 758 // work routine for non-parallel version of remark | |
| 759 void do_remark_non_parallel(); | |
| 760 // reference processing work routine (during second checkpoint) | |
| 761 void refProcessingWork(bool asynch, bool clear_all_soft_refs); | |
| 762 | |
| 763 // concurrent sweeping work | |
| 764 void sweepWork(ConcurrentMarkSweepGeneration* gen, bool asynch); | |
| 765 | |
| 766 // (concurrent) resetting of support data structures | |
| 767 void reset(bool asynch); | |
| 768 | |
| 769 // Clear _expansion_cause fields of constituent generations | |
| 770 void clear_expansion_cause(); | |
| 771 | |
| 772 // An auxilliary method used to record the ends of | |
| 773 // used regions of each generation to limit the extent of sweep | |
| 774 void save_sweep_limits(); | |
| 775 | |
| 776 // Resize the generations included in the collector. | |
| 777 void compute_new_size(); | |
| 778 | |
| 779 // A work method used by foreground collection to determine | |
| 780 // what type of collection (compacting or not, continuing or fresh) | |
| 781 // it should do. | |
| 782 void decide_foreground_collection_type(bool clear_all_soft_refs, | |
| 783 bool* should_compact, bool* should_start_over); | |
| 784 | |
| 785 // A work method used by the foreground collector to do | |
| 786 // a mark-sweep-compact. | |
| 787 void do_compaction_work(bool clear_all_soft_refs); | |
| 788 | |
| 789 // A work method used by the foreground collector to do | |
| 790 // a mark-sweep, after taking over from a possibly on-going | |
| 791 // concurrent mark-sweep collection. | |
| 792 void do_mark_sweep_work(bool clear_all_soft_refs, | |
| 793 CollectorState first_state, bool should_start_over); | |
| 794 | |
| 795 // If the backgrould GC is active, acquire control from the background | |
| 796 // GC and do the collection. | |
| 797 void acquire_control_and_collect(bool full, bool clear_all_soft_refs); | |
| 798 | |
| 799 // For synchronizing passing of control from background to foreground | |
| 800 // GC. waitForForegroundGC() is called by the background | |
| 801 // collector. It if had to wait for a foreground collection, | |
| 802 // it returns true and the background collection should assume | |
| 803 // that the collection was finished by the foreground | |
| 804 // collector. | |
| 805 bool waitForForegroundGC(); | |
| 806 | |
| 807 // Incremental mode triggering: recompute the icms duty cycle and set the | |
| 808 // allocation limits in the young gen. | |
| 809 void icms_update_allocation_limits(); | |
| 810 | |
| 811 size_t block_size_using_printezis_bits(HeapWord* addr) const; | |
| 812 size_t block_size_if_printezis_bits(HeapWord* addr) const; | |
| 813 HeapWord* next_card_start_after_block(HeapWord* addr) const; | |
| 814 | |
| 815 void setup_cms_unloading_and_verification_state(); | |
| 816 public: | |
| 817 CMSCollector(ConcurrentMarkSweepGeneration* cmsGen, | |
| 818 ConcurrentMarkSweepGeneration* permGen, | |
| 819 CardTableRS* ct, | |
| 820 ConcurrentMarkSweepPolicy* cp); | |
| 821 ConcurrentMarkSweepThread* cmsThread() { return _cmsThread; } | |
| 822 | |
| 823 ReferenceProcessor* ref_processor() { return _ref_processor; } | |
| 824 void ref_processor_init(); | |
| 825 | |
| 826 Mutex* bitMapLock() const { return _markBitMap.lock(); } | |
| 827 static CollectorState abstract_state() { return _collectorState; } | |
| 828 | |
| 829 bool should_abort_preclean() const; // Whether preclean should be aborted. | |
| 830 size_t get_eden_used() const; | |
| 831 size_t get_eden_capacity() const; | |
| 832 | |
| 833 ConcurrentMarkSweepGeneration* cmsGen() { return _cmsGen; } | |
| 834 | |
| 835 // locking checks | |
| 836 NOT_PRODUCT(static bool have_cms_token();) | |
| 837 | |
| 838 // XXXPERM bool should_collect(bool full, size_t size, bool tlab); | |
| 839 bool shouldConcurrentCollect(); | |
| 840 | |
| 841 void collect(bool full, | |
| 842 bool clear_all_soft_refs, | |
| 843 size_t size, | |
| 844 bool tlab); | |
| 845 void collect_in_background(bool clear_all_soft_refs); | |
| 846 void collect_in_foreground(bool clear_all_soft_refs); | |
| 847 | |
| 848 // In support of ExplicitGCInvokesConcurrent | |
| 849 static void request_full_gc(unsigned int full_gc_count); | |
| 850 // Should we unload classes in a particular concurrent cycle? | |
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851 bool should_unload_classes() const { |
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852 return _should_unload_classes; |
| 0 | 853 } |
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854 bool update_should_unload_classes(); |
| 0 | 855 |
| 856 void direct_allocated(HeapWord* start, size_t size); | |
| 857 | |
| 858 // Object is dead if not marked and current phase is sweeping. | |
| 859 bool is_dead_obj(oop obj) const; | |
| 860 | |
| 861 // After a promotion (of "start"), do any necessary marking. | |
| 862 // If "par", then it's being done by a parallel GC thread. | |
| 863 // The last two args indicate if we need precise marking | |
| 864 // and if so the size of the object so it can be dirtied | |
| 865 // in its entirety. | |
| 866 void promoted(bool par, HeapWord* start, | |
| 867 bool is_obj_array, size_t obj_size); | |
| 868 | |
| 869 HeapWord* allocation_limit_reached(Space* space, HeapWord* top, | |
| 870 size_t word_size); | |
| 871 | |
| 872 void getFreelistLocks() const; | |
| 873 void releaseFreelistLocks() const; | |
| 874 bool haveFreelistLocks() const; | |
| 875 | |
| 876 // GC prologue and epilogue | |
| 877 void gc_prologue(bool full); | |
| 878 void gc_epilogue(bool full); | |
| 879 | |
| 880 jlong time_of_last_gc(jlong now) { | |
| 881 if (_collectorState <= Idling) { | |
| 882 // gc not in progress | |
| 883 return _time_of_last_gc; | |
| 884 } else { | |
| 885 // collection in progress | |
| 886 return now; | |
| 887 } | |
| 888 } | |
| 889 | |
| 890 // Support for parallel remark of survivor space | |
| 891 void* get_data_recorder(int thr_num); | |
| 892 | |
| 893 CMSBitMap* markBitMap() { return &_markBitMap; } | |
| 894 void directAllocated(HeapWord* start, size_t size); | |
| 895 | |
| 896 // main CMS steps and related support | |
| 897 void checkpointRootsInitial(bool asynch); | |
| 898 bool markFromRoots(bool asynch); // a return value of false indicates failure | |
| 899 // due to stack overflow | |
| 900 void preclean(); | |
| 901 void checkpointRootsFinal(bool asynch, bool clear_all_soft_refs, | |
| 902 bool init_mark_was_synchronous); | |
| 903 void sweep(bool asynch); | |
| 904 | |
| 905 // Check that the currently executing thread is the expected | |
| 906 // one (foreground collector or background collector). | |
| 907 void check_correct_thread_executing() PRODUCT_RETURN; | |
| 908 // XXXPERM void print_statistics() PRODUCT_RETURN; | |
| 909 | |
| 910 bool is_cms_reachable(HeapWord* addr); | |
| 911 | |
| 912 // Performance Counter Support | |
| 913 CollectorCounters* counters() { return _gc_counters; } | |
| 914 | |
| 915 // timer stuff | |
| 916 void startTimer() { assert(!_timer.is_active(), "Error"); _timer.start(); } | |
| 917 void stopTimer() { assert( _timer.is_active(), "Error"); _timer.stop(); } | |
| 918 void resetTimer() { assert(!_timer.is_active(), "Error"); _timer.reset(); } | |
| 919 double timerValue() { assert(!_timer.is_active(), "Error"); return _timer.seconds(); } | |
| 920 | |
| 921 int yields() { return _numYields; } | |
| 922 void resetYields() { _numYields = 0; } | |
| 923 void incrementYields() { _numYields++; } | |
| 924 void resetNumDirtyCards() { _numDirtyCards = 0; } | |
| 925 void incrementNumDirtyCards(size_t num) { _numDirtyCards += num; } | |
| 926 size_t numDirtyCards() { return _numDirtyCards; } | |
| 927 | |
| 928 static bool foregroundGCShouldWait() { return _foregroundGCShouldWait; } | |
| 929 static void set_foregroundGCShouldWait(bool v) { _foregroundGCShouldWait = v; } | |
| 930 static bool foregroundGCIsActive() { return _foregroundGCIsActive; } | |
| 931 static void set_foregroundGCIsActive(bool v) { _foregroundGCIsActive = v; } | |
| 932 uint sweepCount() const { return _sweepCount; } | |
| 933 void incrementSweepCount() { _sweepCount++; } | |
| 934 | |
| 935 // Timers/stats for gc scheduling and incremental mode pacing. | |
| 936 CMSStats& stats() { return _stats; } | |
| 937 | |
| 938 // Convenience methods that check whether CMSIncrementalMode is enabled and | |
| 939 // forward to the corresponding methods in ConcurrentMarkSweepThread. | |
| 940 static void start_icms(); | |
| 941 static void stop_icms(); // Called at the end of the cms cycle. | |
| 942 static void disable_icms(); // Called before a foreground collection. | |
| 943 static void enable_icms(); // Called after a foreground collection. | |
| 944 void icms_wait(); // Called at yield points. | |
| 945 | |
| 946 // Adaptive size policy | |
| 947 CMSAdaptiveSizePolicy* size_policy(); | |
| 948 CMSGCAdaptivePolicyCounters* gc_adaptive_policy_counters(); | |
| 949 | |
| 950 // debugging | |
| 951 void verify(bool); | |
| 952 bool verify_after_remark(); | |
| 953 void verify_ok_to_terminate() const PRODUCT_RETURN; | |
| 954 void verify_work_stacks_empty() const PRODUCT_RETURN; | |
| 955 void verify_overflow_empty() const PRODUCT_RETURN; | |
| 956 | |
| 957 // convenience methods in support of debugging | |
| 958 static const size_t skip_header_HeapWords() PRODUCT_RETURN0; | |
| 959 HeapWord* block_start(const void* p) const PRODUCT_RETURN0; | |
| 960 | |
| 961 // accessors | |
| 962 CMSMarkStack* verification_mark_stack() { return &_markStack; } | |
| 963 CMSBitMap* verification_mark_bm() { return &_verification_mark_bm; } | |
| 964 | |
| 965 // Get the bit map with a perm gen "deadness" information. | |
| 966 CMSBitMap* perm_gen_verify_bit_map() { return &_perm_gen_verify_bit_map; } | |
| 967 | |
| 968 // Initialization errors | |
| 969 bool completed_initialization() { return _completed_initialization; } | |
| 970 }; | |
| 971 | |
| 972 class CMSExpansionCause : public AllStatic { | |
| 973 public: | |
| 974 enum Cause { | |
| 975 _no_expansion, | |
| 976 _satisfy_free_ratio, | |
| 977 _satisfy_promotion, | |
| 978 _satisfy_allocation, | |
| 979 _allocate_par_lab, | |
| 980 _allocate_par_spooling_space, | |
| 981 _adaptive_size_policy | |
| 982 }; | |
| 983 // Return a string describing the cause of the expansion. | |
| 984 static const char* to_string(CMSExpansionCause::Cause cause); | |
| 985 }; | |
| 986 | |
| 987 class ConcurrentMarkSweepGeneration: public CardGeneration { | |
| 988 friend class VMStructs; | |
| 989 friend class ConcurrentMarkSweepThread; | |
| 990 friend class ConcurrentMarkSweep; | |
| 991 friend class CMSCollector; | |
| 992 protected: | |
| 993 static CMSCollector* _collector; // the collector that collects us | |
| 994 CompactibleFreeListSpace* _cmsSpace; // underlying space (only one for now) | |
| 995 | |
| 996 // Performance Counters | |
| 997 GenerationCounters* _gen_counters; | |
| 998 GSpaceCounters* _space_counters; | |
| 999 | |
| 1000 // Words directly allocated, used by CMSStats. | |
| 1001 size_t _direct_allocated_words; | |
| 1002 | |
| 1003 // Non-product stat counters | |
| 1004 NOT_PRODUCT( | |
| 1005 int _numObjectsPromoted; | |
| 1006 int _numWordsPromoted; | |
| 1007 int _numObjectsAllocated; | |
| 1008 int _numWordsAllocated; | |
| 1009 ) | |
| 1010 | |
| 1011 // Used for sizing decisions | |
| 1012 bool _incremental_collection_failed; | |
| 1013 bool incremental_collection_failed() { | |
| 1014 return _incremental_collection_failed; | |
| 1015 } | |
| 1016 void set_incremental_collection_failed() { | |
| 1017 _incremental_collection_failed = true; | |
| 1018 } | |
| 1019 void clear_incremental_collection_failed() { | |
| 1020 _incremental_collection_failed = false; | |
| 1021 } | |
| 1022 | |
|
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1023 // accessors |
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1024 void set_expansion_cause(CMSExpansionCause::Cause v) { _expansion_cause = v;} |
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1025 CMSExpansionCause::Cause expansion_cause() const { return _expansion_cause; } |
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1026 |
| 0 | 1027 private: |
| 1028 // For parallel young-gen GC support. | |
| 1029 CMSParGCThreadState** _par_gc_thread_states; | |
| 1030 | |
| 1031 // Reason generation was expanded | |
| 1032 CMSExpansionCause::Cause _expansion_cause; | |
| 1033 | |
| 1034 // In support of MinChunkSize being larger than min object size | |
| 1035 const double _dilatation_factor; | |
| 1036 | |
| 1037 enum CollectionTypes { | |
| 1038 Concurrent_collection_type = 0, | |
| 1039 MS_foreground_collection_type = 1, | |
| 1040 MSC_foreground_collection_type = 2, | |
| 1041 Unknown_collection_type = 3 | |
| 1042 }; | |
| 1043 | |
| 1044 CollectionTypes _debug_collection_type; | |
| 1045 | |
|
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1046 // Fraction of current occupancy at which to start a CMS collection which |
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1047 // will collect this generation (at least). |
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1048 double _initiating_occupancy; |
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1049 |
| 0 | 1050 protected: |
| 1051 // Grow generation by specified size (returns false if unable to grow) | |
| 1052 bool grow_by(size_t bytes); | |
| 1053 // Grow generation to reserved size. | |
| 1054 bool grow_to_reserved(); | |
| 1055 // Shrink generation by specified size (returns false if unable to shrink) | |
| 1056 virtual void shrink_by(size_t bytes); | |
| 1057 | |
| 1058 // Update statistics for GC | |
| 1059 virtual void update_gc_stats(int level, bool full); | |
| 1060 | |
| 1061 // Maximum available space in the generation (including uncommitted) | |
| 1062 // space. | |
| 1063 size_t max_available() const; | |
| 1064 | |
|
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1065 // getter and initializer for _initiating_occupancy field. |
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1066 double initiating_occupancy() const { return _initiating_occupancy; } |
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1067 void init_initiating_occupancy(intx io, intx tr); |
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1068 |
| 0 | 1069 public: |
| 1070 ConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, | |
| 1071 int level, CardTableRS* ct, | |
| 1072 bool use_adaptive_freelists, | |
| 1073 FreeBlockDictionary::DictionaryChoice); | |
| 1074 | |
| 1075 // Accessors | |
| 1076 CMSCollector* collector() const { return _collector; } | |
| 1077 static void set_collector(CMSCollector* collector) { | |
| 1078 assert(_collector == NULL, "already set"); | |
| 1079 _collector = collector; | |
| 1080 } | |
| 1081 CompactibleFreeListSpace* cmsSpace() const { return _cmsSpace; } | |
| 1082 | |
| 1083 Mutex* freelistLock() const; | |
| 1084 | |
| 1085 virtual Generation::Name kind() { return Generation::ConcurrentMarkSweep; } | |
| 1086 | |
| 1087 // Adaptive size policy | |
| 1088 CMSAdaptiveSizePolicy* size_policy(); | |
| 1089 | |
| 1090 bool refs_discovery_is_atomic() const { return false; } | |
| 1091 bool refs_discovery_is_mt() const { | |
| 1092 // Note: CMS does MT-discovery during the parallel-remark | |
| 1093 // phases. Use ReferenceProcessorMTMutator to make refs | |
| 1094 // discovery MT-safe during such phases or other parallel | |
| 1095 // discovery phases in the future. This may all go away | |
| 1096 // if/when we decide that refs discovery is sufficiently | |
| 1097 // rare that the cost of the CAS's involved is in the | |
| 1098 // noise. That's a measurement that should be done, and | |
| 1099 // the code simplified if that turns out to be the case. | |
| 1100 return false; | |
| 1101 } | |
| 1102 | |
| 1103 // Override | |
| 1104 virtual void ref_processor_init(); | |
| 1105 | |
| 1106 void clear_expansion_cause() { _expansion_cause = CMSExpansionCause::_no_expansion; } | |
| 1107 | |
| 1108 // Space enquiries | |
| 1109 size_t capacity() const; | |
| 1110 size_t used() const; | |
| 1111 size_t free() const; | |
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1112 double occupancy() const { return ((double)used())/((double)capacity()); } |
| 0 | 1113 size_t contiguous_available() const; |
| 1114 size_t unsafe_max_alloc_nogc() const; | |
| 1115 | |
| 1116 // over-rides | |
| 1117 MemRegion used_region() const; | |
| 1118 MemRegion used_region_at_save_marks() const; | |
| 1119 | |
| 1120 // Does a "full" (forced) collection invoked on this generation collect | |
| 1121 // all younger generations as well? Note that the second conjunct is a | |
| 1122 // hack to allow the collection of the younger gen first if the flag is | |
| 1123 // set. This is better than using th policy's should_collect_gen0_first() | |
| 1124 // since that causes us to do an extra unnecessary pair of restart-&-stop-world. | |
| 1125 virtual bool full_collects_younger_generations() const { | |
| 1126 return UseCMSCompactAtFullCollection && !CollectGen0First; | |
| 1127 } | |
| 1128 | |
| 1129 void space_iterate(SpaceClosure* blk, bool usedOnly = false); | |
| 1130 | |
| 1131 // Support for compaction | |
| 1132 CompactibleSpace* first_compaction_space() const; | |
| 1133 // Adjust quantites in the generation affected by | |
| 1134 // the compaction. | |
| 1135 void reset_after_compaction(); | |
| 1136 | |
| 1137 // Allocation support | |
| 1138 HeapWord* allocate(size_t size, bool tlab); | |
| 1139 HeapWord* have_lock_and_allocate(size_t size, bool tlab); | |
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1140 oop promote(oop obj, size_t obj_size); |
| 0 | 1141 HeapWord* par_allocate(size_t size, bool tlab) { |
| 1142 return allocate(size, tlab); | |
| 1143 } | |
| 1144 | |
| 1145 // Incremental mode triggering. | |
| 1146 HeapWord* allocation_limit_reached(Space* space, HeapWord* top, | |
| 1147 size_t word_size); | |
| 1148 | |
| 1149 // Used by CMSStats to track direct allocation. The value is sampled and | |
| 1150 // reset after each young gen collection. | |
| 1151 size_t direct_allocated_words() const { return _direct_allocated_words; } | |
| 1152 void reset_direct_allocated_words() { _direct_allocated_words = 0; } | |
| 1153 | |
| 1154 // Overrides for parallel promotion. | |
| 1155 virtual oop par_promote(int thread_num, | |
| 1156 oop obj, markOop m, size_t word_sz); | |
| 1157 // This one should not be called for CMS. | |
| 1158 virtual void par_promote_alloc_undo(int thread_num, | |
| 1159 HeapWord* obj, size_t word_sz); | |
| 1160 virtual void par_promote_alloc_done(int thread_num); | |
| 1161 virtual void par_oop_since_save_marks_iterate_done(int thread_num); | |
| 1162 | |
| 1163 virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes, | |
| 1164 bool younger_handles_promotion_failure) const; | |
| 1165 | |
| 1166 bool should_collect(bool full, size_t size, bool tlab); | |
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1167 virtual bool should_concurrent_collect() const; |
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1168 virtual bool is_too_full() const; |
| 0 | 1169 void collect(bool full, |
| 1170 bool clear_all_soft_refs, | |
| 1171 size_t size, | |
| 1172 bool tlab); | |
| 1173 | |
| 1174 HeapWord* expand_and_allocate(size_t word_size, | |
| 1175 bool tlab, | |
| 1176 bool parallel = false); | |
| 1177 | |
| 1178 // GC prologue and epilogue | |
| 1179 void gc_prologue(bool full); | |
| 1180 void gc_prologue_work(bool full, bool registerClosure, | |
| 1181 ModUnionClosure* modUnionClosure); | |
| 1182 void gc_epilogue(bool full); | |
| 1183 void gc_epilogue_work(bool full); | |
| 1184 | |
| 1185 // Time since last GC of this generation | |
| 1186 jlong time_of_last_gc(jlong now) { | |
| 1187 return collector()->time_of_last_gc(now); | |
| 1188 } | |
| 1189 void update_time_of_last_gc(jlong now) { | |
| 1190 collector()-> update_time_of_last_gc(now); | |
| 1191 } | |
| 1192 | |
| 1193 // Allocation failure | |
| 1194 void expand(size_t bytes, size_t expand_bytes, | |
| 1195 CMSExpansionCause::Cause cause); | |
| 1196 void shrink(size_t bytes); | |
| 1197 HeapWord* expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz); | |
| 1198 bool expand_and_ensure_spooling_space(PromotionInfo* promo); | |
| 1199 | |
| 1200 // Iteration support and related enquiries | |
| 1201 void save_marks(); | |
| 1202 bool no_allocs_since_save_marks(); | |
| 1203 void object_iterate_since_last_GC(ObjectClosure* cl); | |
| 1204 void younger_refs_iterate(OopsInGenClosure* cl); | |
| 1205 | |
| 1206 // Iteration support specific to CMS generations | |
| 1207 void save_sweep_limit(); | |
| 1208 | |
| 1209 // More iteration support | |
| 1210 virtual void oop_iterate(MemRegion mr, OopClosure* cl); | |
| 1211 virtual void oop_iterate(OopClosure* cl); | |
| 1212 virtual void object_iterate(ObjectClosure* cl); | |
| 1213 | |
| 1214 // Need to declare the full complement of closures, whether we'll | |
| 1215 // override them or not, or get message from the compiler: | |
| 1216 // oop_since_save_marks_iterate_nv hides virtual function... | |
| 1217 #define CMS_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
| 1218 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); | |
| 1219 ALL_SINCE_SAVE_MARKS_CLOSURES(CMS_SINCE_SAVE_MARKS_DECL) | |
| 1220 | |
| 1221 // Smart allocation XXX -- move to CFLSpace? | |
| 1222 void setNearLargestChunk(); | |
| 1223 bool isNearLargestChunk(HeapWord* addr); | |
| 1224 | |
| 1225 // Get the chunk at the end of the space. Delagates to | |
| 1226 // the space. | |
| 1227 FreeChunk* find_chunk_at_end(); | |
| 1228 | |
| 1229 // Overriding of unused functionality (sharing not yet supported with CMS) | |
| 1230 void pre_adjust_pointers(); | |
| 1231 void post_compact(); | |
| 1232 | |
| 1233 // Debugging | |
| 1234 void prepare_for_verify(); | |
| 1235 void verify(bool allow_dirty); | |
| 1236 void print_statistics() PRODUCT_RETURN; | |
| 1237 | |
| 1238 // Performance Counters support | |
| 1239 virtual void update_counters(); | |
| 1240 virtual void update_counters(size_t used); | |
| 1241 void initialize_performance_counters(); | |
| 1242 CollectorCounters* counters() { return collector()->counters(); } | |
| 1243 | |
| 1244 // Support for parallel remark of survivor space | |
| 1245 void* get_data_recorder(int thr_num) { | |
| 1246 //Delegate to collector | |
| 1247 return collector()->get_data_recorder(thr_num); | |
| 1248 } | |
| 1249 | |
| 1250 // Printing | |
| 1251 const char* name() const; | |
| 1252 virtual const char* short_name() const { return "CMS"; } | |
| 1253 void print() const; | |
| 1254 void printOccupancy(const char* s); | |
| 1255 bool must_be_youngest() const { return false; } | |
| 1256 bool must_be_oldest() const { return true; } | |
| 1257 | |
| 1258 void compute_new_size(); | |
| 1259 | |
| 1260 CollectionTypes debug_collection_type() { return _debug_collection_type; } | |
| 1261 void rotate_debug_collection_type(); | |
| 1262 }; | |
| 1263 | |
| 1264 class ASConcurrentMarkSweepGeneration : public ConcurrentMarkSweepGeneration { | |
| 1265 | |
| 1266 // Return the size policy from the heap's collector | |
| 1267 // policy casted to CMSAdaptiveSizePolicy*. | |
| 1268 CMSAdaptiveSizePolicy* cms_size_policy() const; | |
| 1269 | |
| 1270 // Resize the generation based on the adaptive size | |
| 1271 // policy. | |
| 1272 void resize(size_t cur_promo, size_t desired_promo); | |
| 1273 | |
| 1274 // Return the GC counters from the collector policy | |
| 1275 CMSGCAdaptivePolicyCounters* gc_adaptive_policy_counters(); | |
| 1276 | |
| 1277 virtual void shrink_by(size_t bytes); | |
| 1278 | |
| 1279 public: | |
| 1280 virtual void compute_new_size(); | |
| 1281 ASConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, | |
| 1282 int level, CardTableRS* ct, | |
| 1283 bool use_adaptive_freelists, | |
| 1284 FreeBlockDictionary::DictionaryChoice | |
| 1285 dictionaryChoice) : | |
| 1286 ConcurrentMarkSweepGeneration(rs, initial_byte_size, level, ct, | |
| 1287 use_adaptive_freelists, dictionaryChoice) {} | |
| 1288 | |
| 1289 virtual const char* short_name() const { return "ASCMS"; } | |
| 1290 virtual Generation::Name kind() { return Generation::ASConcurrentMarkSweep; } | |
| 1291 | |
| 1292 virtual void update_counters(); | |
| 1293 virtual void update_counters(size_t used); | |
| 1294 }; | |
| 1295 | |
| 1296 // | |
| 1297 // Closures of various sorts used by CMS to accomplish its work | |
| 1298 // | |
| 1299 | |
| 1300 // This closure is used to check that a certain set of oops is empty. | |
| 1301 class FalseClosure: public OopClosure { | |
| 1302 public: | |
|
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1303 void do_oop(oop* p) { guarantee(false, "Should be an empty set"); } |
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1304 void do_oop(narrowOop* p) { guarantee(false, "Should be an empty set"); } |
| 0 | 1305 }; |
| 1306 | |
| 1307 // This closure is used to do concurrent marking from the roots | |
| 1308 // following the first checkpoint. | |
| 1309 class MarkFromRootsClosure: public BitMapClosure { | |
| 1310 CMSCollector* _collector; | |
| 1311 MemRegion _span; | |
| 1312 CMSBitMap* _bitMap; | |
| 1313 CMSBitMap* _mut; | |
| 1314 CMSMarkStack* _markStack; | |
| 1315 CMSMarkStack* _revisitStack; | |
| 1316 bool _yield; | |
| 1317 int _skipBits; | |
| 1318 HeapWord* _finger; | |
| 1319 HeapWord* _threshold; | |
| 1320 DEBUG_ONLY(bool _verifying;) | |
| 1321 | |
| 1322 public: | |
| 1323 MarkFromRootsClosure(CMSCollector* collector, MemRegion span, | |
| 1324 CMSBitMap* bitMap, | |
| 1325 CMSMarkStack* markStack, | |
| 1326 CMSMarkStack* revisitStack, | |
| 1327 bool should_yield, bool verifying = false); | |
| 1328 void do_bit(size_t offset); | |
| 1329 void reset(HeapWord* addr); | |
| 1330 inline void do_yield_check(); | |
| 1331 | |
| 1332 private: | |
| 1333 void scanOopsInOop(HeapWord* ptr); | |
| 1334 void do_yield_work(); | |
| 1335 }; | |
| 1336 | |
| 1337 // This closure is used to do concurrent multi-threaded | |
| 1338 // marking from the roots following the first checkpoint. | |
| 1339 // XXX This should really be a subclass of The serial version | |
| 1340 // above, but i have not had the time to refactor things cleanly. | |
| 1341 // That willbe done for Dolphin. | |
| 1342 class Par_MarkFromRootsClosure: public BitMapClosure { | |
| 1343 CMSCollector* _collector; | |
| 1344 MemRegion _whole_span; | |
| 1345 MemRegion _span; | |
| 1346 CMSBitMap* _bit_map; | |
| 1347 CMSBitMap* _mut; | |
| 1348 OopTaskQueue* _work_queue; | |
| 1349 CMSMarkStack* _overflow_stack; | |
| 1350 CMSMarkStack* _revisit_stack; | |
| 1351 bool _yield; | |
| 1352 int _skip_bits; | |
| 1353 HeapWord* _finger; | |
| 1354 HeapWord* _threshold; | |
| 1355 CMSConcMarkingTask* _task; | |
| 1356 public: | |
| 1357 Par_MarkFromRootsClosure(CMSConcMarkingTask* task, CMSCollector* collector, | |
| 1358 MemRegion span, | |
| 1359 CMSBitMap* bit_map, | |
| 1360 OopTaskQueue* work_queue, | |
| 1361 CMSMarkStack* overflow_stack, | |
| 1362 CMSMarkStack* revisit_stack, | |
| 1363 bool should_yield); | |
| 1364 void do_bit(size_t offset); | |
| 1365 inline void do_yield_check(); | |
| 1366 | |
| 1367 private: | |
| 1368 void scan_oops_in_oop(HeapWord* ptr); | |
| 1369 void do_yield_work(); | |
| 1370 bool get_work_from_overflow_stack(); | |
| 1371 }; | |
| 1372 | |
| 1373 // The following closures are used to do certain kinds of verification of | |
| 1374 // CMS marking. | |
| 1375 class PushAndMarkVerifyClosure: public OopClosure { | |
| 1376 CMSCollector* _collector; | |
| 1377 MemRegion _span; | |
| 1378 CMSBitMap* _verification_bm; | |
| 1379 CMSBitMap* _cms_bm; | |
| 1380 CMSMarkStack* _mark_stack; | |
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1381 protected: |
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1382 void do_oop(oop p); |
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1383 template <class T> inline void do_oop_work(T *p) { |
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1384 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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1385 do_oop(obj); |
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1386 } |
| 0 | 1387 public: |
| 1388 PushAndMarkVerifyClosure(CMSCollector* cms_collector, | |
| 1389 MemRegion span, | |
| 1390 CMSBitMap* verification_bm, | |
| 1391 CMSBitMap* cms_bm, | |
| 1392 CMSMarkStack* mark_stack); | |
| 1393 void do_oop(oop* p); | |
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1394 void do_oop(narrowOop* p); |
| 0 | 1395 // Deal with a stack overflow condition |
| 1396 void handle_stack_overflow(HeapWord* lost); | |
| 1397 }; | |
| 1398 | |
| 1399 class MarkFromRootsVerifyClosure: public BitMapClosure { | |
| 1400 CMSCollector* _collector; | |
| 1401 MemRegion _span; | |
| 1402 CMSBitMap* _verification_bm; | |
| 1403 CMSBitMap* _cms_bm; | |
| 1404 CMSMarkStack* _mark_stack; | |
| 1405 HeapWord* _finger; | |
| 1406 PushAndMarkVerifyClosure _pam_verify_closure; | |
| 1407 public: | |
| 1408 MarkFromRootsVerifyClosure(CMSCollector* collector, MemRegion span, | |
| 1409 CMSBitMap* verification_bm, | |
| 1410 CMSBitMap* cms_bm, | |
| 1411 CMSMarkStack* mark_stack); | |
| 1412 void do_bit(size_t offset); | |
| 1413 void reset(HeapWord* addr); | |
| 1414 }; | |
| 1415 | |
| 1416 | |
| 1417 // This closure is used to check that a certain set of bits is | |
| 1418 // "empty" (i.e. the bit vector doesn't have any 1-bits). | |
| 1419 class FalseBitMapClosure: public BitMapClosure { | |
| 1420 public: | |
| 1421 void do_bit(size_t offset) { | |
| 1422 guarantee(false, "Should not have a 1 bit"); | |
| 1423 } | |
| 1424 }; | |
| 1425 | |
| 1426 // This closure is used during the second checkpointing phase | |
| 1427 // to rescan the marked objects on the dirty cards in the mod | |
| 1428 // union table and the card table proper. It's invoked via | |
| 1429 // MarkFromDirtyCardsClosure below. It uses either | |
| 1430 // [Par_]MarkRefsIntoAndScanClosure (Par_ in the parallel case) | |
| 1431 // declared in genOopClosures.hpp to accomplish some of its work. | |
| 1432 // In the parallel case the bitMap is shared, so access to | |
| 1433 // it needs to be suitably synchronized for updates by embedded | |
| 1434 // closures that update it; however, this closure itself only | |
| 1435 // reads the bit_map and because it is idempotent, is immune to | |
| 1436 // reading stale values. | |
| 1437 class ScanMarkedObjectsAgainClosure: public UpwardsObjectClosure { | |
| 1438 #ifdef ASSERT | |
| 1439 CMSCollector* _collector; | |
| 1440 MemRegion _span; | |
| 1441 union { | |
| 1442 CMSMarkStack* _mark_stack; | |
| 1443 OopTaskQueue* _work_queue; | |
| 1444 }; | |
| 1445 #endif // ASSERT | |
| 1446 bool _parallel; | |
| 1447 CMSBitMap* _bit_map; | |
| 1448 union { | |
| 1449 MarkRefsIntoAndScanClosure* _scan_closure; | |
| 1450 Par_MarkRefsIntoAndScanClosure* _par_scan_closure; | |
| 1451 }; | |
| 1452 | |
| 1453 public: | |
| 1454 ScanMarkedObjectsAgainClosure(CMSCollector* collector, | |
| 1455 MemRegion span, | |
| 1456 ReferenceProcessor* rp, | |
| 1457 CMSBitMap* bit_map, | |
| 1458 CMSMarkStack* mark_stack, | |
| 1459 CMSMarkStack* revisit_stack, | |
| 1460 MarkRefsIntoAndScanClosure* cl): | |
| 1461 #ifdef ASSERT | |
| 1462 _collector(collector), | |
| 1463 _span(span), | |
| 1464 _mark_stack(mark_stack), | |
| 1465 #endif // ASSERT | |
| 1466 _parallel(false), | |
| 1467 _bit_map(bit_map), | |
| 1468 _scan_closure(cl) { } | |
| 1469 | |
| 1470 ScanMarkedObjectsAgainClosure(CMSCollector* collector, | |
| 1471 MemRegion span, | |
| 1472 ReferenceProcessor* rp, | |
| 1473 CMSBitMap* bit_map, | |
| 1474 OopTaskQueue* work_queue, | |
| 1475 CMSMarkStack* revisit_stack, | |
| 1476 Par_MarkRefsIntoAndScanClosure* cl): | |
| 1477 #ifdef ASSERT | |
| 1478 _collector(collector), | |
| 1479 _span(span), | |
| 1480 _work_queue(work_queue), | |
| 1481 #endif // ASSERT | |
| 1482 _parallel(true), | |
| 1483 _bit_map(bit_map), | |
| 1484 _par_scan_closure(cl) { } | |
| 1485 | |
| 1486 void do_object(oop obj) { | |
| 1487 guarantee(false, "Call do_object_b(oop, MemRegion) instead"); | |
| 1488 } | |
| 1489 bool do_object_b(oop obj) { | |
| 1490 guarantee(false, "Call do_object_b(oop, MemRegion) form instead"); | |
| 1491 return false; | |
| 1492 } | |
| 1493 bool do_object_bm(oop p, MemRegion mr); | |
| 1494 }; | |
| 1495 | |
| 1496 // This closure is used during the second checkpointing phase | |
| 1497 // to rescan the marked objects on the dirty cards in the mod | |
| 1498 // union table and the card table proper. It invokes | |
| 1499 // ScanMarkedObjectsAgainClosure above to accomplish much of its work. | |
| 1500 // In the parallel case, the bit map is shared and requires | |
| 1501 // synchronized access. | |
| 1502 class MarkFromDirtyCardsClosure: public MemRegionClosure { | |
| 1503 CompactibleFreeListSpace* _space; | |
| 1504 ScanMarkedObjectsAgainClosure _scan_cl; | |
| 1505 size_t _num_dirty_cards; | |
| 1506 | |
| 1507 public: | |
| 1508 MarkFromDirtyCardsClosure(CMSCollector* collector, | |
| 1509 MemRegion span, | |
| 1510 CompactibleFreeListSpace* space, | |
| 1511 CMSBitMap* bit_map, | |
| 1512 CMSMarkStack* mark_stack, | |
| 1513 CMSMarkStack* revisit_stack, | |
| 1514 MarkRefsIntoAndScanClosure* cl): | |
| 1515 _space(space), | |
| 1516 _num_dirty_cards(0), | |
| 1517 _scan_cl(collector, span, collector->ref_processor(), bit_map, | |
| 1518 mark_stack, revisit_stack, cl) { } | |
| 1519 | |
| 1520 MarkFromDirtyCardsClosure(CMSCollector* collector, | |
| 1521 MemRegion span, | |
| 1522 CompactibleFreeListSpace* space, | |
| 1523 CMSBitMap* bit_map, | |
| 1524 OopTaskQueue* work_queue, | |
| 1525 CMSMarkStack* revisit_stack, | |
| 1526 Par_MarkRefsIntoAndScanClosure* cl): | |
| 1527 _space(space), | |
| 1528 _num_dirty_cards(0), | |
| 1529 _scan_cl(collector, span, collector->ref_processor(), bit_map, | |
| 1530 work_queue, revisit_stack, cl) { } | |
| 1531 | |
| 1532 void do_MemRegion(MemRegion mr); | |
| 1533 void set_space(CompactibleFreeListSpace* space) { _space = space; } | |
| 1534 size_t num_dirty_cards() { return _num_dirty_cards; } | |
| 1535 }; | |
| 1536 | |
| 1537 // This closure is used in the non-product build to check | |
| 1538 // that there are no MemRegions with a certain property. | |
| 1539 class FalseMemRegionClosure: public MemRegionClosure { | |
| 1540 void do_MemRegion(MemRegion mr) { | |
| 1541 guarantee(!mr.is_empty(), "Shouldn't be empty"); | |
| 1542 guarantee(false, "Should never be here"); | |
| 1543 } | |
| 1544 }; | |
| 1545 | |
| 1546 // This closure is used during the precleaning phase | |
| 1547 // to "carefully" rescan marked objects on dirty cards. | |
| 1548 // It uses MarkRefsIntoAndScanClosure declared in genOopClosures.hpp | |
| 1549 // to accomplish some of its work. | |
| 1550 class ScanMarkedObjectsAgainCarefullyClosure: public ObjectClosureCareful { | |
| 1551 CMSCollector* _collector; | |
| 1552 MemRegion _span; | |
| 1553 bool _yield; | |
| 1554 Mutex* _freelistLock; | |
| 1555 CMSBitMap* _bitMap; | |
| 1556 CMSMarkStack* _markStack; | |
| 1557 MarkRefsIntoAndScanClosure* _scanningClosure; | |
| 1558 | |
| 1559 public: | |
| 1560 ScanMarkedObjectsAgainCarefullyClosure(CMSCollector* collector, | |
| 1561 MemRegion span, | |
| 1562 CMSBitMap* bitMap, | |
| 1563 CMSMarkStack* markStack, | |
| 1564 CMSMarkStack* revisitStack, | |
| 1565 MarkRefsIntoAndScanClosure* cl, | |
| 1566 bool should_yield): | |
| 1567 _collector(collector), | |
| 1568 _span(span), | |
| 1569 _yield(should_yield), | |
| 1570 _bitMap(bitMap), | |
| 1571 _markStack(markStack), | |
| 1572 _scanningClosure(cl) { | |
| 1573 } | |
| 1574 | |
| 1575 void do_object(oop p) { | |
| 1576 guarantee(false, "call do_object_careful instead"); | |
| 1577 } | |
| 1578 | |
| 1579 size_t do_object_careful(oop p) { | |
| 1580 guarantee(false, "Unexpected caller"); | |
| 1581 return 0; | |
| 1582 } | |
| 1583 | |
| 1584 size_t do_object_careful_m(oop p, MemRegion mr); | |
| 1585 | |
| 1586 void setFreelistLock(Mutex* m) { | |
| 1587 _freelistLock = m; | |
| 1588 _scanningClosure->set_freelistLock(m); | |
| 1589 } | |
| 1590 | |
| 1591 private: | |
| 1592 inline bool do_yield_check(); | |
| 1593 | |
| 1594 void do_yield_work(); | |
| 1595 }; | |
| 1596 | |
| 1597 class SurvivorSpacePrecleanClosure: public ObjectClosureCareful { | |
| 1598 CMSCollector* _collector; | |
| 1599 MemRegion _span; | |
| 1600 bool _yield; | |
| 1601 CMSBitMap* _bit_map; | |
| 1602 CMSMarkStack* _mark_stack; | |
| 1603 PushAndMarkClosure* _scanning_closure; | |
| 1604 unsigned int _before_count; | |
| 1605 | |
| 1606 public: | |
| 1607 SurvivorSpacePrecleanClosure(CMSCollector* collector, | |
| 1608 MemRegion span, | |
| 1609 CMSBitMap* bit_map, | |
| 1610 CMSMarkStack* mark_stack, | |
| 1611 PushAndMarkClosure* cl, | |
| 1612 unsigned int before_count, | |
| 1613 bool should_yield): | |
| 1614 _collector(collector), | |
| 1615 _span(span), | |
| 1616 _yield(should_yield), | |
| 1617 _bit_map(bit_map), | |
| 1618 _mark_stack(mark_stack), | |
| 1619 _scanning_closure(cl), | |
| 1620 _before_count(before_count) | |
| 1621 { } | |
| 1622 | |
| 1623 void do_object(oop p) { | |
| 1624 guarantee(false, "call do_object_careful instead"); | |
| 1625 } | |
| 1626 | |
| 1627 size_t do_object_careful(oop p); | |
| 1628 | |
| 1629 size_t do_object_careful_m(oop p, MemRegion mr) { | |
| 1630 guarantee(false, "Unexpected caller"); | |
| 1631 return 0; | |
| 1632 } | |
| 1633 | |
| 1634 private: | |
| 1635 inline void do_yield_check(); | |
| 1636 void do_yield_work(); | |
| 1637 }; | |
| 1638 | |
| 1639 // This closure is used to accomplish the sweeping work | |
| 1640 // after the second checkpoint but before the concurrent reset | |
| 1641 // phase. | |
| 1642 // | |
| 1643 // Terminology | |
| 1644 // left hand chunk (LHC) - block of one or more chunks currently being | |
| 1645 // coalesced. The LHC is available for coalescing with a new chunk. | |
| 1646 // right hand chunk (RHC) - block that is currently being swept that is | |
| 1647 // free or garbage that can be coalesced with the LHC. | |
| 1648 // _inFreeRange is true if there is currently a LHC | |
| 1649 // _lastFreeRangeCoalesced is true if the LHC consists of more than one chunk. | |
| 1650 // _freeRangeInFreeLists is true if the LHC is in the free lists. | |
| 1651 // _freeFinger is the address of the current LHC | |
| 1652 class SweepClosure: public BlkClosureCareful { | |
| 1653 CMSCollector* _collector; // collector doing the work | |
| 1654 ConcurrentMarkSweepGeneration* _g; // Generation being swept | |
| 1655 CompactibleFreeListSpace* _sp; // Space being swept | |
| 1656 HeapWord* _limit; | |
| 1657 Mutex* _freelistLock; // Free list lock (in space) | |
| 1658 CMSBitMap* _bitMap; // Marking bit map (in | |
| 1659 // generation) | |
| 1660 bool _inFreeRange; // Indicates if we are in the | |
| 1661 // midst of a free run | |
| 1662 bool _freeRangeInFreeLists; | |
| 1663 // Often, we have just found | |
| 1664 // a free chunk and started | |
| 1665 // a new free range; we do not | |
| 1666 // eagerly remove this chunk from | |
| 1667 // the free lists unless there is | |
| 1668 // a possibility of coalescing. | |
| 1669 // When true, this flag indicates | |
| 1670 // that the _freeFinger below | |
| 1671 // points to a potentially free chunk | |
| 1672 // that may still be in the free lists | |
| 1673 bool _lastFreeRangeCoalesced; | |
| 1674 // free range contains chunks | |
| 1675 // coalesced | |
| 1676 bool _yield; | |
| 1677 // Whether sweeping should be | |
| 1678 // done with yields. For instance | |
| 1679 // when done by the foreground | |
| 1680 // collector we shouldn't yield. | |
| 1681 HeapWord* _freeFinger; // When _inFreeRange is set, the | |
| 1682 // pointer to the "left hand | |
| 1683 // chunk" | |
| 1684 size_t _freeRangeSize; | |
| 1685 // When _inFreeRange is set, this | |
| 1686 // indicates the accumulated size | |
| 1687 // of the "left hand chunk" | |
| 1688 NOT_PRODUCT( | |
| 1689 size_t _numObjectsFreed; | |
| 1690 size_t _numWordsFreed; | |
| 1691 size_t _numObjectsLive; | |
| 1692 size_t _numWordsLive; | |
| 1693 size_t _numObjectsAlreadyFree; | |
| 1694 size_t _numWordsAlreadyFree; | |
| 1695 FreeChunk* _last_fc; | |
| 1696 ) | |
| 1697 private: | |
| 1698 // Code that is common to a free chunk or garbage when | |
| 1699 // encountered during sweeping. | |
| 1700 void doPostIsFreeOrGarbageChunk(FreeChunk *fc, | |
| 1701 size_t chunkSize); | |
| 1702 // Process a free chunk during sweeping. | |
| 1703 void doAlreadyFreeChunk(FreeChunk *fc); | |
| 1704 // Process a garbage chunk during sweeping. | |
| 1705 size_t doGarbageChunk(FreeChunk *fc); | |
| 1706 // Process a live chunk during sweeping. | |
| 1707 size_t doLiveChunk(FreeChunk* fc); | |
| 1708 | |
| 1709 // Accessors. | |
| 1710 HeapWord* freeFinger() const { return _freeFinger; } | |
| 1711 void set_freeFinger(HeapWord* v) { _freeFinger = v; } | |
| 1712 size_t freeRangeSize() const { return _freeRangeSize; } | |
| 1713 void set_freeRangeSize(size_t v) { _freeRangeSize = v; } | |
| 1714 bool inFreeRange() const { return _inFreeRange; } | |
| 1715 void set_inFreeRange(bool v) { _inFreeRange = v; } | |
| 1716 bool lastFreeRangeCoalesced() const { return _lastFreeRangeCoalesced; } | |
| 1717 void set_lastFreeRangeCoalesced(bool v) { _lastFreeRangeCoalesced = v; } | |
| 1718 bool freeRangeInFreeLists() const { return _freeRangeInFreeLists; } | |
| 1719 void set_freeRangeInFreeLists(bool v) { _freeRangeInFreeLists = v; } | |
| 1720 | |
| 1721 // Initialize a free range. | |
| 1722 void initialize_free_range(HeapWord* freeFinger, bool freeRangeInFreeLists); | |
| 1723 // Return this chunk to the free lists. | |
| 1724 void flushCurFreeChunk(HeapWord* chunk, size_t size); | |
| 1725 | |
| 1726 // Check if we should yield and do so when necessary. | |
| 1727 inline void do_yield_check(HeapWord* addr); | |
| 1728 | |
| 1729 // Yield | |
| 1730 void do_yield_work(HeapWord* addr); | |
| 1731 | |
| 1732 // Debugging/Printing | |
| 1733 void record_free_block_coalesced(FreeChunk* fc) const PRODUCT_RETURN; | |
| 1734 | |
| 1735 public: | |
| 1736 SweepClosure(CMSCollector* collector, ConcurrentMarkSweepGeneration* g, | |
| 1737 CMSBitMap* bitMap, bool should_yield); | |
| 1738 ~SweepClosure(); | |
| 1739 | |
| 1740 size_t do_blk_careful(HeapWord* addr); | |
| 1741 }; | |
| 1742 | |
| 1743 // Closures related to weak references processing | |
| 1744 | |
| 1745 // During CMS' weak reference processing, this is a | |
| 1746 // work-routine/closure used to complete transitive | |
| 1747 // marking of objects as live after a certain point | |
| 1748 // in which an initial set has been completely accumulated. | |
| 1749 class CMSDrainMarkingStackClosure: public VoidClosure { | |
| 1750 CMSCollector* _collector; | |
| 1751 MemRegion _span; | |
| 1752 CMSMarkStack* _mark_stack; | |
| 1753 CMSBitMap* _bit_map; | |
| 1754 CMSKeepAliveClosure* _keep_alive; | |
| 1755 public: | |
| 1756 CMSDrainMarkingStackClosure(CMSCollector* collector, MemRegion span, | |
| 1757 CMSBitMap* bit_map, CMSMarkStack* mark_stack, | |
| 1758 CMSKeepAliveClosure* keep_alive): | |
| 1759 _collector(collector), | |
| 1760 _span(span), | |
| 1761 _bit_map(bit_map), | |
| 1762 _mark_stack(mark_stack), | |
| 1763 _keep_alive(keep_alive) { } | |
| 1764 | |
| 1765 void do_void(); | |
| 1766 }; | |
| 1767 | |
| 1768 // A parallel version of CMSDrainMarkingStackClosure above. | |
| 1769 class CMSParDrainMarkingStackClosure: public VoidClosure { | |
| 1770 CMSCollector* _collector; | |
| 1771 MemRegion _span; | |
| 1772 OopTaskQueue* _work_queue; | |
| 1773 CMSBitMap* _bit_map; | |
| 1774 CMSInnerParMarkAndPushClosure _mark_and_push; | |
| 1775 | |
| 1776 public: | |
| 1777 CMSParDrainMarkingStackClosure(CMSCollector* collector, | |
| 1778 MemRegion span, CMSBitMap* bit_map, | |
| 1779 OopTaskQueue* work_queue): | |
| 1780 _collector(collector), | |
| 1781 _span(span), | |
| 1782 _bit_map(bit_map), | |
| 1783 _work_queue(work_queue), | |
| 1784 _mark_and_push(collector, span, bit_map, work_queue) { } | |
| 1785 | |
| 1786 public: | |
| 1787 void trim_queue(uint max); | |
| 1788 void do_void(); | |
| 1789 }; | |
| 1790 | |
| 1791 // Allow yielding or short-circuiting of reference list | |
| 1792 // prelceaning work. | |
| 1793 class CMSPrecleanRefsYieldClosure: public YieldClosure { | |
| 1794 CMSCollector* _collector; | |
| 1795 void do_yield_work(); | |
| 1796 public: | |
| 1797 CMSPrecleanRefsYieldClosure(CMSCollector* collector): | |
| 1798 _collector(collector) {} | |
| 1799 virtual bool should_return(); | |
| 1800 }; | |
| 1801 | |
| 1802 | |
| 1803 // Convenience class that locks free list locks for given CMS collector | |
| 1804 class FreelistLocker: public StackObj { | |
| 1805 private: | |
| 1806 CMSCollector* _collector; | |
| 1807 public: | |
| 1808 FreelistLocker(CMSCollector* collector): | |
| 1809 _collector(collector) { | |
| 1810 _collector->getFreelistLocks(); | |
| 1811 } | |
| 1812 | |
| 1813 ~FreelistLocker() { | |
| 1814 _collector->releaseFreelistLocks(); | |
| 1815 } | |
| 1816 }; | |
| 1817 | |
| 1818 // Mark all dead objects in a given space. | |
| 1819 class MarkDeadObjectsClosure: public BlkClosure { | |
| 1820 const CMSCollector* _collector; | |
| 1821 const CompactibleFreeListSpace* _sp; | |
| 1822 CMSBitMap* _live_bit_map; | |
| 1823 CMSBitMap* _dead_bit_map; | |
| 1824 public: | |
| 1825 MarkDeadObjectsClosure(const CMSCollector* collector, | |
| 1826 const CompactibleFreeListSpace* sp, | |
| 1827 CMSBitMap *live_bit_map, | |
| 1828 CMSBitMap *dead_bit_map) : | |
| 1829 _collector(collector), | |
| 1830 _sp(sp), | |
| 1831 _live_bit_map(live_bit_map), | |
| 1832 _dead_bit_map(dead_bit_map) {} | |
| 1833 size_t do_blk(HeapWord* addr); | |
| 1834 }; |