1 /* 2 * Copyright (c) 2001, 2014, 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_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc_implementation/g1/concurrentMark.hpp" 29 #include "gc_implementation/g1/evacuationInfo.hpp" 30 #include "gc_implementation/g1/g1AllocRegion.hpp" 31 #include "gc_implementation/g1/g1BiasedArray.hpp" 32 #include "gc_implementation/g1/g1HRPrinter.hpp" 33 #include "gc_implementation/g1/g1MonitoringSupport.hpp" 34 #include "gc_implementation/g1/g1RemSet.hpp" 35 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp" 36 #include "gc_implementation/g1/g1YCTypes.hpp" 37 #include "gc_implementation/g1/heapRegionSeq.hpp" 38 #include "gc_implementation/g1/heapRegionSet.hpp" 39 #include "gc_implementation/shared/hSpaceCounters.hpp" 40 #include "gc_implementation/shared/parGCAllocBuffer.hpp" 41 #include "memory/barrierSet.hpp" 42 #include "memory/memRegion.hpp" 43 #include "memory/sharedHeap.hpp" 44 #include "utilities/stack.hpp" 45 46 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 47 // It uses the "Garbage First" heap organization and algorithm, which 48 // may combine concurrent marking with parallel, incremental compaction of 49 // heap subsets that will yield large amounts of garbage. 50 51 // Forward declarations 52 class HeapRegion; 53 class HRRSCleanupTask; 54 class GenerationSpec; 55 class OopsInHeapRegionClosure; 56 class G1KlassScanClosure; 57 class G1ScanHeapEvacClosure; 58 class ObjectClosure; 59 class SpaceClosure; 60 class CompactibleSpaceClosure; 61 class Space; 62 class G1CollectorPolicy; 63 class GenRemSet; 64 class G1RemSet; 65 class HeapRegionRemSetIterator; 66 class ConcurrentMark; 67 class ConcurrentMarkThread; 68 class ConcurrentG1Refine; 69 class ConcurrentGCTimer; 70 class GenerationCounters; 71 class STWGCTimer; 72 class G1NewTracer; 73 class G1OldTracer; 74 class EvacuationFailedInfo; 75 class nmethod; 76 class Ticks; 77 78 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 79 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 80 81 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 82 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 83 84 enum GCAllocPurpose { 85 GCAllocForTenured, 86 GCAllocForSurvived, 87 GCAllocPurposeCount 88 }; 89 90 class YoungList : public CHeapObj<mtGC> { 91 private: 92 G1CollectedHeap* _g1h; 93 94 HeapRegion* _head; 95 96 HeapRegion* _survivor_head; 97 HeapRegion* _survivor_tail; 98 99 HeapRegion* _curr; 100 101 uint _length; 102 uint _survivor_length; 103 104 size_t _last_sampled_rs_lengths; 105 size_t _sampled_rs_lengths; 106 107 void empty_list(HeapRegion* list); 108 109 public: 110 YoungList(G1CollectedHeap* g1h); 111 112 void push_region(HeapRegion* hr); 113 void add_survivor_region(HeapRegion* hr); 114 115 void empty_list(); 116 bool is_empty() { return _length == 0; } 117 uint length() { return _length; } 118 uint survivor_length() { return _survivor_length; } 119 120 // Currently we do not keep track of the used byte sum for the 121 // young list and the survivors and it'd be quite a lot of work to 122 // do so. When we'll eventually replace the young list with 123 // instances of HeapRegionLinkedList we'll get that for free. So, 124 // we'll report the more accurate information then. 125 size_t eden_used_bytes() { 126 assert(length() >= survivor_length(), "invariant"); 127 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 128 } 129 size_t survivor_used_bytes() { 130 return (size_t) survivor_length() * HeapRegion::GrainBytes; 131 } 132 133 void rs_length_sampling_init(); 134 bool rs_length_sampling_more(); 135 void rs_length_sampling_next(); 136 137 void reset_sampled_info() { 138 _last_sampled_rs_lengths = 0; 139 } 140 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 141 142 // for development purposes 143 void reset_auxilary_lists(); 144 void clear() { _head = NULL; _length = 0; } 145 146 void clear_survivors() { 147 _survivor_head = NULL; 148 _survivor_tail = NULL; 149 _survivor_length = 0; 150 } 151 152 HeapRegion* first_region() { return _head; } 153 HeapRegion* first_survivor_region() { return _survivor_head; } 154 HeapRegion* last_survivor_region() { return _survivor_tail; } 155 156 // debugging 157 bool check_list_well_formed(); 158 bool check_list_empty(bool check_sample = true); 159 void print(); 160 }; 161 162 class MutatorAllocRegion : public G1AllocRegion { 163 protected: 164 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 165 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 166 public: 167 MutatorAllocRegion() 168 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 169 }; 170 171 class SurvivorGCAllocRegion : public G1AllocRegion { 172 protected: 173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 175 public: 176 SurvivorGCAllocRegion() 177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { } 178 }; 179 180 class OldGCAllocRegion : public G1AllocRegion { 181 protected: 182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 184 public: 185 OldGCAllocRegion() 186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { } 187 }; 188 189 // The G1 STW is alive closure. 190 // An instance is embedded into the G1CH and used as the 191 // (optional) _is_alive_non_header closure in the STW 192 // reference processor. It is also extensively used during 193 // reference processing during STW evacuation pauses. 194 class G1STWIsAliveClosure: public BoolObjectClosure { 195 G1CollectedHeap* _g1; 196 public: 197 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 198 bool do_object_b(oop p); 199 }; 200 201 // Instances of this class are used for quick tests on whether a reference points 202 // into the collection set. Each of the array's elements denotes whether the 203 // corresponding region is in the collection set. 204 class G1FastCSetBiasedMappedArray : public G1BiasedMappedArray<bool> { 205 protected: 206 bool default_value() const { return false; } 207 public: 208 void clear() { G1BiasedMappedArray<bool>::clear(); } 209 }; 210 211 class RefineCardTableEntryClosure; 212 213 class G1CollectedHeap : public SharedHeap { 214 friend class VM_G1CollectForAllocation; 215 friend class VM_G1CollectFull; 216 friend class VM_G1IncCollectionPause; 217 friend class VMStructs; 218 friend class MutatorAllocRegion; 219 friend class SurvivorGCAllocRegion; 220 friend class OldGCAllocRegion; 221 222 // Closures used in implementation. 223 template <G1Barrier barrier, bool do_mark_object> 224 friend class G1ParCopyClosure; 225 friend class G1IsAliveClosure; 226 friend class G1EvacuateFollowersClosure; 227 friend class G1ParScanThreadState; 228 friend class G1ParScanClosureSuper; 229 friend class G1ParEvacuateFollowersClosure; 230 friend class G1ParTask; 231 friend class G1FreeGarbageRegionClosure; 232 friend class RefineCardTableEntryClosure; 233 friend class G1PrepareCompactClosure; 234 friend class RegionSorter; 235 friend class RegionResetter; 236 friend class CountRCClosure; 237 friend class EvacPopObjClosure; 238 friend class G1ParCleanupCTTask; 239 240 // Other related classes. 241 friend class G1MarkSweep; 242 243 private: 244 // The one and only G1CollectedHeap, so static functions can find it. 245 static G1CollectedHeap* _g1h; 246 247 static size_t _humongous_object_threshold_in_words; 248 249 // Storage for the G1 heap. 250 VirtualSpace _g1_storage; 251 MemRegion _g1_reserved; 252 253 // The part of _g1_storage that is currently committed. 254 MemRegion _g1_committed; 255 256 // The master free list. It will satisfy all new region allocations. 257 FreeRegionList _free_list; 258 259 // The secondary free list which contains regions that have been 260 // freed up during the cleanup process. This will be appended to the 261 // master free list when appropriate. 262 FreeRegionList _secondary_free_list; 263 264 // It keeps track of the old regions. 265 HeapRegionSet _old_set; 266 267 // It keeps track of the humongous regions. 268 HeapRegionSet _humongous_set; 269 270 // The number of regions we could create by expansion. 271 uint _expansion_regions; 272 273 // The block offset table for the G1 heap. 274 G1BlockOffsetSharedArray* _bot_shared; 275 276 // Tears down the region sets / lists so that they are empty and the 277 // regions on the heap do not belong to a region set / list. The 278 // only exception is the humongous set which we leave unaltered. If 279 // free_list_only is true, it will only tear down the master free 280 // list. It is called before a Full GC (free_list_only == false) or 281 // before heap shrinking (free_list_only == true). 282 void tear_down_region_sets(bool free_list_only); 283 284 // Rebuilds the region sets / lists so that they are repopulated to 285 // reflect the contents of the heap. The only exception is the 286 // humongous set which was not torn down in the first place. If 287 // free_list_only is true, it will only rebuild the master free 288 // list. It is called after a Full GC (free_list_only == false) or 289 // after heap shrinking (free_list_only == true). 290 void rebuild_region_sets(bool free_list_only); 291 292 // The sequence of all heap regions in the heap. 293 HeapRegionSeq _hrs; 294 295 // Alloc region used to satisfy mutator allocation requests. 296 MutatorAllocRegion _mutator_alloc_region; 297 298 // Alloc region used to satisfy allocation requests by the GC for 299 // survivor objects. 300 SurvivorGCAllocRegion _survivor_gc_alloc_region; 301 302 // PLAB sizing policy for survivors. 303 PLABStats _survivor_plab_stats; 304 305 // Alloc region used to satisfy allocation requests by the GC for 306 // old objects. 307 OldGCAllocRegion _old_gc_alloc_region; 308 309 // PLAB sizing policy for tenured objects. 310 PLABStats _old_plab_stats; 311 312 PLABStats* stats_for_purpose(GCAllocPurpose purpose) { 313 PLABStats* stats = NULL; 314 315 switch (purpose) { 316 case GCAllocForSurvived: 317 stats = &_survivor_plab_stats; 318 break; 319 case GCAllocForTenured: 320 stats = &_old_plab_stats; 321 break; 322 default: 323 assert(false, "unrecognized GCAllocPurpose"); 324 } 325 326 return stats; 327 } 328 329 // The last old region we allocated to during the last GC. 330 // Typically, it is not full so we should re-use it during the next GC. 331 HeapRegion* _retained_old_gc_alloc_region; 332 333 // It specifies whether we should attempt to expand the heap after a 334 // region allocation failure. If heap expansion fails we set this to 335 // false so that we don't re-attempt the heap expansion (it's likely 336 // that subsequent expansion attempts will also fail if one fails). 337 // Currently, it is only consulted during GC and it's reset at the 338 // start of each GC. 339 bool _expand_heap_after_alloc_failure; 340 341 // It resets the mutator alloc region before new allocations can take place. 342 void init_mutator_alloc_region(); 343 344 // It releases the mutator alloc region. 345 void release_mutator_alloc_region(); 346 347 // It initializes the GC alloc regions at the start of a GC. 348 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 349 350 // It releases the GC alloc regions at the end of a GC. 351 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 352 353 // It does any cleanup that needs to be done on the GC alloc regions 354 // before a Full GC. 355 void abandon_gc_alloc_regions(); 356 357 // Helper for monitoring and management support. 358 G1MonitoringSupport* _g1mm; 359 360 // Determines PLAB size for a particular allocation purpose. 361 size_t desired_plab_sz(GCAllocPurpose purpose); 362 363 // Outside of GC pauses, the number of bytes used in all regions other 364 // than the current allocation region. 365 size_t _summary_bytes_used; 366 367 // This array is used for a quick test on whether a reference points into 368 // the collection set or not. Each of the array's elements denotes whether the 369 // corresponding region is in the collection set or not. 370 G1FastCSetBiasedMappedArray _in_cset_fast_test; 371 372 volatile unsigned _gc_time_stamp; 373 374 size_t* _surviving_young_words; 375 376 G1HRPrinter _hr_printer; 377 378 void setup_surviving_young_words(); 379 void update_surviving_young_words(size_t* surv_young_words); 380 void cleanup_surviving_young_words(); 381 382 // It decides whether an explicit GC should start a concurrent cycle 383 // instead of doing a STW GC. Currently, a concurrent cycle is 384 // explicitly started if: 385 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 386 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 387 // (c) cause == _g1_humongous_allocation 388 bool should_do_concurrent_full_gc(GCCause::Cause cause); 389 390 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 391 // concurrent cycles) we have started. 392 volatile unsigned int _old_marking_cycles_started; 393 394 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 395 // concurrent cycles) we have completed. 396 volatile unsigned int _old_marking_cycles_completed; 397 398 bool _concurrent_cycle_started; 399 400 // This is a non-product method that is helpful for testing. It is 401 // called at the end of a GC and artificially expands the heap by 402 // allocating a number of dead regions. This way we can induce very 403 // frequent marking cycles and stress the cleanup / concurrent 404 // cleanup code more (as all the regions that will be allocated by 405 // this method will be found dead by the marking cycle). 406 void allocate_dummy_regions() PRODUCT_RETURN; 407 408 // Clear RSets after a compaction. It also resets the GC time stamps. 409 void clear_rsets_post_compaction(); 410 411 // If the HR printer is active, dump the state of the regions in the 412 // heap after a compaction. 413 void print_hrs_post_compaction(); 414 415 double verify(bool guard, const char* msg); 416 void verify_before_gc(); 417 void verify_after_gc(); 418 419 void log_gc_header(); 420 void log_gc_footer(double pause_time_sec); 421 422 // These are macros so that, if the assert fires, we get the correct 423 // line number, file, etc. 424 425 #define heap_locking_asserts_err_msg(_extra_message_) \ 426 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 427 (_extra_message_), \ 428 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 429 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 430 BOOL_TO_STR(Thread::current()->is_VM_thread())) 431 432 #define assert_heap_locked() \ 433 do { \ 434 assert(Heap_lock->owned_by_self(), \ 435 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 436 } while (0) 437 438 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 439 do { \ 440 assert(Heap_lock->owned_by_self() || \ 441 (SafepointSynchronize::is_at_safepoint() && \ 442 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 443 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 444 "should be at a safepoint")); \ 445 } while (0) 446 447 #define assert_heap_locked_and_not_at_safepoint() \ 448 do { \ 449 assert(Heap_lock->owned_by_self() && \ 450 !SafepointSynchronize::is_at_safepoint(), \ 451 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 452 "should not be at a safepoint")); \ 453 } while (0) 454 455 #define assert_heap_not_locked() \ 456 do { \ 457 assert(!Heap_lock->owned_by_self(), \ 458 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 459 } while (0) 460 461 #define assert_heap_not_locked_and_not_at_safepoint() \ 462 do { \ 463 assert(!Heap_lock->owned_by_self() && \ 464 !SafepointSynchronize::is_at_safepoint(), \ 465 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 466 "should not be at a safepoint")); \ 467 } while (0) 468 469 #define assert_at_safepoint(_should_be_vm_thread_) \ 470 do { \ 471 assert(SafepointSynchronize::is_at_safepoint() && \ 472 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 473 heap_locking_asserts_err_msg("should be at a safepoint")); \ 474 } while (0) 475 476 #define assert_not_at_safepoint() \ 477 do { \ 478 assert(!SafepointSynchronize::is_at_safepoint(), \ 479 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 480 } while (0) 481 482 protected: 483 484 // The young region list. 485 YoungList* _young_list; 486 487 // The current policy object for the collector. 488 G1CollectorPolicy* _g1_policy; 489 490 // This is the second level of trying to allocate a new region. If 491 // new_region() didn't find a region on the free_list, this call will 492 // check whether there's anything available on the 493 // secondary_free_list and/or wait for more regions to appear on 494 // that list, if _free_regions_coming is set. 495 HeapRegion* new_region_try_secondary_free_list(bool is_old); 496 497 // Try to allocate a single non-humongous HeapRegion sufficient for 498 // an allocation of the given word_size. If do_expand is true, 499 // attempt to expand the heap if necessary to satisfy the allocation 500 // request. If the region is to be used as an old region or for a 501 // humongous object, set is_old to true. If not, to false. 502 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 503 504 // Attempt to satisfy a humongous allocation request of the given 505 // size by finding a contiguous set of free regions of num_regions 506 // length and remove them from the master free list. Return the 507 // index of the first region or G1_NULL_HRS_INDEX if the search 508 // was unsuccessful. 509 uint humongous_obj_allocate_find_first(uint num_regions, 510 size_t word_size); 511 512 // Initialize a contiguous set of free regions of length num_regions 513 // and starting at index first so that they appear as a single 514 // humongous region. 515 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 516 uint num_regions, 517 size_t word_size); 518 519 // Attempt to allocate a humongous object of the given size. Return 520 // NULL if unsuccessful. 521 HeapWord* humongous_obj_allocate(size_t word_size); 522 523 // The following two methods, allocate_new_tlab() and 524 // mem_allocate(), are the two main entry points from the runtime 525 // into the G1's allocation routines. They have the following 526 // assumptions: 527 // 528 // * They should both be called outside safepoints. 529 // 530 // * They should both be called without holding the Heap_lock. 531 // 532 // * All allocation requests for new TLABs should go to 533 // allocate_new_tlab(). 534 // 535 // * All non-TLAB allocation requests should go to mem_allocate(). 536 // 537 // * If either call cannot satisfy the allocation request using the 538 // current allocating region, they will try to get a new one. If 539 // this fails, they will attempt to do an evacuation pause and 540 // retry the allocation. 541 // 542 // * If all allocation attempts fail, even after trying to schedule 543 // an evacuation pause, allocate_new_tlab() will return NULL, 544 // whereas mem_allocate() will attempt a heap expansion and/or 545 // schedule a Full GC. 546 // 547 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 548 // should never be called with word_size being humongous. All 549 // humongous allocation requests should go to mem_allocate() which 550 // will satisfy them with a special path. 551 552 virtual HeapWord* allocate_new_tlab(size_t word_size); 553 554 virtual HeapWord* mem_allocate(size_t word_size, 555 bool* gc_overhead_limit_was_exceeded); 556 557 // The following three methods take a gc_count_before_ret 558 // parameter which is used to return the GC count if the method 559 // returns NULL. Given that we are required to read the GC count 560 // while holding the Heap_lock, and these paths will take the 561 // Heap_lock at some point, it's easier to get them to read the GC 562 // count while holding the Heap_lock before they return NULL instead 563 // of the caller (namely: mem_allocate()) having to also take the 564 // Heap_lock just to read the GC count. 565 566 // First-level mutator allocation attempt: try to allocate out of 567 // the mutator alloc region without taking the Heap_lock. This 568 // should only be used for non-humongous allocations. 569 inline HeapWord* attempt_allocation(size_t word_size, 570 unsigned int* gc_count_before_ret, 571 int* gclocker_retry_count_ret); 572 573 // Second-level mutator allocation attempt: take the Heap_lock and 574 // retry the allocation attempt, potentially scheduling a GC 575 // pause. This should only be used for non-humongous allocations. 576 HeapWord* attempt_allocation_slow(size_t word_size, 577 unsigned int* gc_count_before_ret, 578 int* gclocker_retry_count_ret); 579 580 // Takes the Heap_lock and attempts a humongous allocation. It can 581 // potentially schedule a GC pause. 582 HeapWord* attempt_allocation_humongous(size_t word_size, 583 unsigned int* gc_count_before_ret, 584 int* gclocker_retry_count_ret); 585 586 // Allocation attempt that should be called during safepoints (e.g., 587 // at the end of a successful GC). expect_null_mutator_alloc_region 588 // specifies whether the mutator alloc region is expected to be NULL 589 // or not. 590 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 591 bool expect_null_mutator_alloc_region); 592 593 // It dirties the cards that cover the block so that so that the post 594 // write barrier never queues anything when updating objects on this 595 // block. It is assumed (and in fact we assert) that the block 596 // belongs to a young region. 597 inline void dirty_young_block(HeapWord* start, size_t word_size); 598 599 // Allocate blocks during garbage collection. Will ensure an 600 // allocation region, either by picking one or expanding the 601 // heap, and then allocate a block of the given size. The block 602 // may not be a humongous - it must fit into a single heap region. 603 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 604 605 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 606 HeapRegion* alloc_region, 607 bool par, 608 size_t word_size); 609 610 // Ensure that no further allocations can happen in "r", bearing in mind 611 // that parallel threads might be attempting allocations. 612 void par_allocate_remaining_space(HeapRegion* r); 613 614 // Allocation attempt during GC for a survivor object / PLAB. 615 inline HeapWord* survivor_attempt_allocation(size_t word_size); 616 617 // Allocation attempt during GC for an old object / PLAB. 618 inline HeapWord* old_attempt_allocation(size_t word_size); 619 620 // These methods are the "callbacks" from the G1AllocRegion class. 621 622 // For mutator alloc regions. 623 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 624 void retire_mutator_alloc_region(HeapRegion* alloc_region, 625 size_t allocated_bytes); 626 627 // For GC alloc regions. 628 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 629 GCAllocPurpose ap); 630 void retire_gc_alloc_region(HeapRegion* alloc_region, 631 size_t allocated_bytes, GCAllocPurpose ap); 632 633 // - if explicit_gc is true, the GC is for a System.gc() or a heap 634 // inspection request and should collect the entire heap 635 // - if clear_all_soft_refs is true, all soft references should be 636 // cleared during the GC 637 // - if explicit_gc is false, word_size describes the allocation that 638 // the GC should attempt (at least) to satisfy 639 // - it returns false if it is unable to do the collection due to the 640 // GC locker being active, true otherwise 641 bool do_collection(bool explicit_gc, 642 bool clear_all_soft_refs, 643 size_t word_size); 644 645 // Callback from VM_G1CollectFull operation. 646 // Perform a full collection. 647 virtual void do_full_collection(bool clear_all_soft_refs); 648 649 // Resize the heap if necessary after a full collection. If this is 650 // after a collect-for allocation, "word_size" is the allocation size, 651 // and will be considered part of the used portion of the heap. 652 void resize_if_necessary_after_full_collection(size_t word_size); 653 654 // Callback from VM_G1CollectForAllocation operation. 655 // This function does everything necessary/possible to satisfy a 656 // failed allocation request (including collection, expansion, etc.) 657 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 658 659 // Attempting to expand the heap sufficiently 660 // to support an allocation of the given "word_size". If 661 // successful, perform the allocation and return the address of the 662 // allocated block, or else "NULL". 663 HeapWord* expand_and_allocate(size_t word_size); 664 665 // Process any reference objects discovered during 666 // an incremental evacuation pause. 667 void process_discovered_references(uint no_of_gc_workers); 668 669 // Enqueue any remaining discovered references 670 // after processing. 671 void enqueue_discovered_references(uint no_of_gc_workers); 672 673 public: 674 675 G1MonitoringSupport* g1mm() { 676 assert(_g1mm != NULL, "should have been initialized"); 677 return _g1mm; 678 } 679 680 // Expand the garbage-first heap by at least the given size (in bytes!). 681 // Returns true if the heap was expanded by the requested amount; 682 // false otherwise. 683 // (Rounds up to a HeapRegion boundary.) 684 bool expand(size_t expand_bytes); 685 686 // Do anything common to GC's. 687 virtual void gc_prologue(bool full); 688 virtual void gc_epilogue(bool full); 689 690 // We register a region with the fast "in collection set" test. We 691 // simply set to true the array slot corresponding to this region. 692 void register_region_with_in_cset_fast_test(HeapRegion* r) { 693 _in_cset_fast_test.set_by_index(r->hrs_index(), true); 694 } 695 696 // This is a fast test on whether a reference points into the 697 // collection set or not. Assume that the reference 698 // points into the heap. 699 inline bool in_cset_fast_test(oop obj); 700 701 void clear_cset_fast_test() { 702 _in_cset_fast_test.clear(); 703 } 704 705 // This is called at the start of either a concurrent cycle or a Full 706 // GC to update the number of old marking cycles started. 707 void increment_old_marking_cycles_started(); 708 709 // This is called at the end of either a concurrent cycle or a Full 710 // GC to update the number of old marking cycles completed. Those two 711 // can happen in a nested fashion, i.e., we start a concurrent 712 // cycle, a Full GC happens half-way through it which ends first, 713 // and then the cycle notices that a Full GC happened and ends 714 // too. The concurrent parameter is a boolean to help us do a bit 715 // tighter consistency checking in the method. If concurrent is 716 // false, the caller is the inner caller in the nesting (i.e., the 717 // Full GC). If concurrent is true, the caller is the outer caller 718 // in this nesting (i.e., the concurrent cycle). Further nesting is 719 // not currently supported. The end of this call also notifies 720 // the FullGCCount_lock in case a Java thread is waiting for a full 721 // GC to happen (e.g., it called System.gc() with 722 // +ExplicitGCInvokesConcurrent). 723 void increment_old_marking_cycles_completed(bool concurrent); 724 725 unsigned int old_marking_cycles_completed() { 726 return _old_marking_cycles_completed; 727 } 728 729 void register_concurrent_cycle_start(const Ticks& start_time); 730 void register_concurrent_cycle_end(); 731 void trace_heap_after_concurrent_cycle(); 732 733 G1YCType yc_type(); 734 735 G1HRPrinter* hr_printer() { return &_hr_printer; } 736 737 // Frees a non-humongous region by initializing its contents and 738 // adding it to the free list that's passed as a parameter (this is 739 // usually a local list which will be appended to the master free 740 // list later). The used bytes of freed regions are accumulated in 741 // pre_used. If par is true, the region's RSet will not be freed 742 // up. The assumption is that this will be done later. 743 // The locked parameter indicates if the caller has already taken 744 // care of proper synchronization. This may allow some optimizations. 745 void free_region(HeapRegion* hr, 746 FreeRegionList* free_list, 747 bool par, 748 bool locked = false); 749 750 // Frees a humongous region by collapsing it into individual regions 751 // and calling free_region() for each of them. The freed regions 752 // will be added to the free list that's passed as a parameter (this 753 // is usually a local list which will be appended to the master free 754 // list later). The used bytes of freed regions are accumulated in 755 // pre_used. If par is true, the region's RSet will not be freed 756 // up. The assumption is that this will be done later. 757 void free_humongous_region(HeapRegion* hr, 758 FreeRegionList* free_list, 759 bool par); 760 protected: 761 762 // Shrink the garbage-first heap by at most the given size (in bytes!). 763 // (Rounds down to a HeapRegion boundary.) 764 virtual void shrink(size_t expand_bytes); 765 void shrink_helper(size_t expand_bytes); 766 767 #if TASKQUEUE_STATS 768 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 769 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 770 void reset_taskqueue_stats(); 771 #endif // TASKQUEUE_STATS 772 773 // Schedule the VM operation that will do an evacuation pause to 774 // satisfy an allocation request of word_size. *succeeded will 775 // return whether the VM operation was successful (it did do an 776 // evacuation pause) or not (another thread beat us to it or the GC 777 // locker was active). Given that we should not be holding the 778 // Heap_lock when we enter this method, we will pass the 779 // gc_count_before (i.e., total_collections()) as a parameter since 780 // it has to be read while holding the Heap_lock. Currently, both 781 // methods that call do_collection_pause() release the Heap_lock 782 // before the call, so it's easy to read gc_count_before just before. 783 HeapWord* do_collection_pause(size_t word_size, 784 unsigned int gc_count_before, 785 bool* succeeded, 786 GCCause::Cause gc_cause); 787 788 // The guts of the incremental collection pause, executed by the vm 789 // thread. It returns false if it is unable to do the collection due 790 // to the GC locker being active, true otherwise 791 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 792 793 // Actually do the work of evacuating the collection set. 794 void evacuate_collection_set(EvacuationInfo& evacuation_info); 795 796 // The g1 remembered set of the heap. 797 G1RemSet* _g1_rem_set; 798 799 // A set of cards that cover the objects for which the Rsets should be updated 800 // concurrently after the collection. 801 DirtyCardQueueSet _dirty_card_queue_set; 802 803 // The closure used to refine a single card. 804 RefineCardTableEntryClosure* _refine_cte_cl; 805 806 // A function to check the consistency of dirty card logs. 807 void check_ct_logs_at_safepoint(); 808 809 // A DirtyCardQueueSet that is used to hold cards that contain 810 // references into the current collection set. This is used to 811 // update the remembered sets of the regions in the collection 812 // set in the event of an evacuation failure. 813 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 814 815 // After a collection pause, make the regions in the CS into free 816 // regions. 817 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 818 819 // Abandon the current collection set without recording policy 820 // statistics or updating free lists. 821 void abandon_collection_set(HeapRegion* cs_head); 822 823 // Applies "scan_non_heap_roots" to roots outside the heap, 824 // "scan_rs" to roots inside the heap (having done "set_region" to 825 // indicate the region in which the root resides), 826 // and does "scan_metadata" If "scan_rs" is 827 // NULL, then this step is skipped. The "worker_i" 828 // param is for use with parallel roots processing, and should be 829 // the "i" of the calling parallel worker thread's work(i) function. 830 // In the sequential case this param will be ignored. 831 void g1_process_strong_roots(bool is_scavenging, 832 ScanningOption so, 833 OopClosure* scan_non_heap_roots, 834 OopsInHeapRegionClosure* scan_rs, 835 G1KlassScanClosure* scan_klasses, 836 uint worker_i); 837 838 // Apply "blk" to all the weak roots of the system. These include 839 // JNI weak roots, the code cache, system dictionary, symbol table, 840 // string table, and referents of reachable weak refs. 841 void g1_process_weak_roots(OopClosure* root_closure); 842 843 // Notifies all the necessary spaces that the committed space has 844 // been updated (either expanded or shrunk). It should be called 845 // after _g1_storage is updated. 846 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 847 848 // The concurrent marker (and the thread it runs in.) 849 ConcurrentMark* _cm; 850 ConcurrentMarkThread* _cmThread; 851 bool _mark_in_progress; 852 853 // The concurrent refiner. 854 ConcurrentG1Refine* _cg1r; 855 856 // The parallel task queues 857 RefToScanQueueSet *_task_queues; 858 859 // True iff a evacuation has failed in the current collection. 860 bool _evacuation_failed; 861 862 EvacuationFailedInfo* _evacuation_failed_info_array; 863 864 // Failed evacuations cause some logical from-space objects to have 865 // forwarding pointers to themselves. Reset them. 866 void remove_self_forwarding_pointers(); 867 868 // Together, these store an object with a preserved mark, and its mark value. 869 Stack<oop, mtGC> _objs_with_preserved_marks; 870 Stack<markOop, mtGC> _preserved_marks_of_objs; 871 872 // Preserve the mark of "obj", if necessary, in preparation for its mark 873 // word being overwritten with a self-forwarding-pointer. 874 void preserve_mark_if_necessary(oop obj, markOop m); 875 876 // The stack of evac-failure objects left to be scanned. 877 GrowableArray<oop>* _evac_failure_scan_stack; 878 // The closure to apply to evac-failure objects. 879 880 OopsInHeapRegionClosure* _evac_failure_closure; 881 // Set the field above. 882 void 883 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 884 _evac_failure_closure = evac_failure_closure; 885 } 886 887 // Push "obj" on the scan stack. 888 void push_on_evac_failure_scan_stack(oop obj); 889 // Process scan stack entries until the stack is empty. 890 void drain_evac_failure_scan_stack(); 891 // True iff an invocation of "drain_scan_stack" is in progress; to 892 // prevent unnecessary recursion. 893 bool _drain_in_progress; 894 895 // Do any necessary initialization for evacuation-failure handling. 896 // "cl" is the closure that will be used to process evac-failure 897 // objects. 898 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 899 // Do any necessary cleanup for evacuation-failure handling data 900 // structures. 901 void finalize_for_evac_failure(); 902 903 // An attempt to evacuate "obj" has failed; take necessary steps. 904 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 905 void handle_evacuation_failure_common(oop obj, markOop m); 906 907 #ifndef PRODUCT 908 // Support for forcing evacuation failures. Analogous to 909 // PromotionFailureALot for the other collectors. 910 911 // Records whether G1EvacuationFailureALot should be in effect 912 // for the current GC 913 bool _evacuation_failure_alot_for_current_gc; 914 915 // Used to record the GC number for interval checking when 916 // determining whether G1EvaucationFailureALot is in effect 917 // for the current GC. 918 size_t _evacuation_failure_alot_gc_number; 919 920 // Count of the number of evacuations between failures. 921 volatile size_t _evacuation_failure_alot_count; 922 923 // Set whether G1EvacuationFailureALot should be in effect 924 // for the current GC (based upon the type of GC and which 925 // command line flags are set); 926 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 927 bool during_initial_mark, 928 bool during_marking); 929 930 inline void set_evacuation_failure_alot_for_current_gc(); 931 932 // Return true if it's time to cause an evacuation failure. 933 inline bool evacuation_should_fail(); 934 935 // Reset the G1EvacuationFailureALot counters. Should be called at 936 // the end of an evacuation pause in which an evacuation failure occurred. 937 inline void reset_evacuation_should_fail(); 938 #endif // !PRODUCT 939 940 // ("Weak") Reference processing support. 941 // 942 // G1 has 2 instances of the reference processor class. One 943 // (_ref_processor_cm) handles reference object discovery 944 // and subsequent processing during concurrent marking cycles. 945 // 946 // The other (_ref_processor_stw) handles reference object 947 // discovery and processing during full GCs and incremental 948 // evacuation pauses. 949 // 950 // During an incremental pause, reference discovery will be 951 // temporarily disabled for _ref_processor_cm and will be 952 // enabled for _ref_processor_stw. At the end of the evacuation 953 // pause references discovered by _ref_processor_stw will be 954 // processed and discovery will be disabled. The previous 955 // setting for reference object discovery for _ref_processor_cm 956 // will be re-instated. 957 // 958 // At the start of marking: 959 // * Discovery by the CM ref processor is verified to be inactive 960 // and it's discovered lists are empty. 961 // * Discovery by the CM ref processor is then enabled. 962 // 963 // At the end of marking: 964 // * Any references on the CM ref processor's discovered 965 // lists are processed (possibly MT). 966 // 967 // At the start of full GC we: 968 // * Disable discovery by the CM ref processor and 969 // empty CM ref processor's discovered lists 970 // (without processing any entries). 971 // * Verify that the STW ref processor is inactive and it's 972 // discovered lists are empty. 973 // * Temporarily set STW ref processor discovery as single threaded. 974 // * Temporarily clear the STW ref processor's _is_alive_non_header 975 // field. 976 // * Finally enable discovery by the STW ref processor. 977 // 978 // The STW ref processor is used to record any discovered 979 // references during the full GC. 980 // 981 // At the end of a full GC we: 982 // * Enqueue any reference objects discovered by the STW ref processor 983 // that have non-live referents. This has the side-effect of 984 // making the STW ref processor inactive by disabling discovery. 985 // * Verify that the CM ref processor is still inactive 986 // and no references have been placed on it's discovered 987 // lists (also checked as a precondition during initial marking). 988 989 // The (stw) reference processor... 990 ReferenceProcessor* _ref_processor_stw; 991 992 STWGCTimer* _gc_timer_stw; 993 ConcurrentGCTimer* _gc_timer_cm; 994 995 G1OldTracer* _gc_tracer_cm; 996 G1NewTracer* _gc_tracer_stw; 997 998 // During reference object discovery, the _is_alive_non_header 999 // closure (if non-null) is applied to the referent object to 1000 // determine whether the referent is live. If so then the 1001 // reference object does not need to be 'discovered' and can 1002 // be treated as a regular oop. This has the benefit of reducing 1003 // the number of 'discovered' reference objects that need to 1004 // be processed. 1005 // 1006 // Instance of the is_alive closure for embedding into the 1007 // STW reference processor as the _is_alive_non_header field. 1008 // Supplying a value for the _is_alive_non_header field is 1009 // optional but doing so prevents unnecessary additions to 1010 // the discovered lists during reference discovery. 1011 G1STWIsAliveClosure _is_alive_closure_stw; 1012 1013 // The (concurrent marking) reference processor... 1014 ReferenceProcessor* _ref_processor_cm; 1015 1016 // Instance of the concurrent mark is_alive closure for embedding 1017 // into the Concurrent Marking reference processor as the 1018 // _is_alive_non_header field. Supplying a value for the 1019 // _is_alive_non_header field is optional but doing so prevents 1020 // unnecessary additions to the discovered lists during reference 1021 // discovery. 1022 G1CMIsAliveClosure _is_alive_closure_cm; 1023 1024 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1025 HeapRegion** _worker_cset_start_region; 1026 1027 // Time stamp to validate the regions recorded in the cache 1028 // used by G1CollectedHeap::start_cset_region_for_worker(). 1029 // The heap region entry for a given worker is valid iff 1030 // the associated time stamp value matches the current value 1031 // of G1CollectedHeap::_gc_time_stamp. 1032 unsigned int* _worker_cset_start_region_time_stamp; 1033 1034 enum G1H_process_strong_roots_tasks { 1035 G1H_PS_filter_satb_buffers, 1036 G1H_PS_refProcessor_oops_do, 1037 // Leave this one last. 1038 G1H_PS_NumElements 1039 }; 1040 1041 SubTasksDone* _process_strong_tasks; 1042 1043 volatile bool _free_regions_coming; 1044 1045 public: 1046 1047 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1048 1049 void set_refine_cte_cl_concurrency(bool concurrent); 1050 1051 RefToScanQueue *task_queue(int i) const; 1052 1053 // A set of cards where updates happened during the GC 1054 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1055 1056 // A DirtyCardQueueSet that is used to hold cards that contain 1057 // references into the current collection set. This is used to 1058 // update the remembered sets of the regions in the collection 1059 // set in the event of an evacuation failure. 1060 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1061 { return _into_cset_dirty_card_queue_set; } 1062 1063 // Create a G1CollectedHeap with the specified policy. 1064 // Must call the initialize method afterwards. 1065 // May not return if something goes wrong. 1066 G1CollectedHeap(G1CollectorPolicy* policy); 1067 1068 // Initialize the G1CollectedHeap to have the initial and 1069 // maximum sizes and remembered and barrier sets 1070 // specified by the policy object. 1071 jint initialize(); 1072 1073 virtual void stop(); 1074 1075 // Return the (conservative) maximum heap alignment for any G1 heap 1076 static size_t conservative_max_heap_alignment(); 1077 1078 // Initialize weak reference processing. 1079 virtual void ref_processing_init(); 1080 1081 void set_par_threads(uint t) { 1082 SharedHeap::set_par_threads(t); 1083 // Done in SharedHeap but oddly there are 1084 // two _process_strong_tasks's in a G1CollectedHeap 1085 // so do it here too. 1086 _process_strong_tasks->set_n_threads(t); 1087 } 1088 1089 // Set _n_par_threads according to a policy TBD. 1090 void set_par_threads(); 1091 1092 void set_n_termination(int t) { 1093 _process_strong_tasks->set_n_threads(t); 1094 } 1095 1096 virtual CollectedHeap::Name kind() const { 1097 return CollectedHeap::G1CollectedHeap; 1098 } 1099 1100 // The current policy object for the collector. 1101 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1102 1103 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1104 1105 // Adaptive size policy. No such thing for g1. 1106 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1107 1108 // The rem set and barrier set. 1109 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1110 1111 unsigned get_gc_time_stamp() { 1112 return _gc_time_stamp; 1113 } 1114 1115 inline void reset_gc_time_stamp(); 1116 1117 void check_gc_time_stamps() PRODUCT_RETURN; 1118 1119 inline void increment_gc_time_stamp(); 1120 1121 // Reset the given region's GC timestamp. If it's starts humongous, 1122 // also reset the GC timestamp of its corresponding 1123 // continues humongous regions too. 1124 void reset_gc_time_stamps(HeapRegion* hr); 1125 1126 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1127 DirtyCardQueue* into_cset_dcq, 1128 bool concurrent, uint worker_i); 1129 1130 // The shared block offset table array. 1131 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1132 1133 // Reference Processing accessors 1134 1135 // The STW reference processor.... 1136 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1137 1138 // The Concurrent Marking reference processor... 1139 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1140 1141 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1142 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1143 1144 virtual size_t capacity() const; 1145 virtual size_t used() const; 1146 // This should be called when we're not holding the heap lock. The 1147 // result might be a bit inaccurate. 1148 size_t used_unlocked() const; 1149 size_t recalculate_used() const; 1150 1151 // These virtual functions do the actual allocation. 1152 // Some heaps may offer a contiguous region for shared non-blocking 1153 // allocation, via inlined code (by exporting the address of the top and 1154 // end fields defining the extent of the contiguous allocation region.) 1155 // But G1CollectedHeap doesn't yet support this. 1156 1157 // Return an estimate of the maximum allocation that could be performed 1158 // without triggering any collection or expansion activity. In a 1159 // generational collector, for example, this is probably the largest 1160 // allocation that could be supported (without expansion) in the youngest 1161 // generation. It is "unsafe" because no locks are taken; the result 1162 // should be treated as an approximation, not a guarantee, for use in 1163 // heuristic resizing decisions. 1164 virtual size_t unsafe_max_alloc(); 1165 1166 virtual bool is_maximal_no_gc() const { 1167 return _g1_storage.uncommitted_size() == 0; 1168 } 1169 1170 // The total number of regions in the heap. 1171 uint n_regions() { return _hrs.length(); } 1172 1173 // The max number of regions in the heap. 1174 uint max_regions() { return _hrs.max_length(); } 1175 1176 // The number of regions that are completely free. 1177 uint free_regions() { return _free_list.length(); } 1178 1179 // The number of regions that are not completely free. 1180 uint used_regions() { return n_regions() - free_regions(); } 1181 1182 // The number of regions available for "regular" expansion. 1183 uint expansion_regions() { return _expansion_regions; } 1184 1185 // Factory method for HeapRegion instances. It will return NULL if 1186 // the allocation fails. 1187 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1188 1189 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1190 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1191 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1192 void verify_dirty_young_regions() PRODUCT_RETURN; 1193 1194 // verify_region_sets() performs verification over the region 1195 // lists. It will be compiled in the product code to be used when 1196 // necessary (i.e., during heap verification). 1197 void verify_region_sets(); 1198 1199 // verify_region_sets_optional() is planted in the code for 1200 // list verification in non-product builds (and it can be enabled in 1201 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1202 #if HEAP_REGION_SET_FORCE_VERIFY 1203 void verify_region_sets_optional() { 1204 verify_region_sets(); 1205 } 1206 #else // HEAP_REGION_SET_FORCE_VERIFY 1207 void verify_region_sets_optional() { } 1208 #endif // HEAP_REGION_SET_FORCE_VERIFY 1209 1210 #ifdef ASSERT 1211 bool is_on_master_free_list(HeapRegion* hr) { 1212 return hr->containing_set() == &_free_list; 1213 } 1214 #endif // ASSERT 1215 1216 // Wrapper for the region list operations that can be called from 1217 // methods outside this class. 1218 1219 void secondary_free_list_add(FreeRegionList* list) { 1220 _secondary_free_list.add_ordered(list); 1221 } 1222 1223 void append_secondary_free_list() { 1224 _free_list.add_ordered(&_secondary_free_list); 1225 } 1226 1227 void append_secondary_free_list_if_not_empty_with_lock() { 1228 // If the secondary free list looks empty there's no reason to 1229 // take the lock and then try to append it. 1230 if (!_secondary_free_list.is_empty()) { 1231 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1232 append_secondary_free_list(); 1233 } 1234 } 1235 1236 inline void old_set_remove(HeapRegion* hr); 1237 1238 size_t non_young_capacity_bytes() { 1239 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1240 } 1241 1242 void set_free_regions_coming(); 1243 void reset_free_regions_coming(); 1244 bool free_regions_coming() { return _free_regions_coming; } 1245 void wait_while_free_regions_coming(); 1246 1247 // Determine whether the given region is one that we are using as an 1248 // old GC alloc region. 1249 bool is_old_gc_alloc_region(HeapRegion* hr) { 1250 return hr == _retained_old_gc_alloc_region; 1251 } 1252 1253 // Perform a collection of the heap; intended for use in implementing 1254 // "System.gc". This probably implies as full a collection as the 1255 // "CollectedHeap" supports. 1256 virtual void collect(GCCause::Cause cause); 1257 1258 // The same as above but assume that the caller holds the Heap_lock. 1259 void collect_locked(GCCause::Cause cause); 1260 1261 // True iff an evacuation has failed in the most-recent collection. 1262 bool evacuation_failed() { return _evacuation_failed; } 1263 1264 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1265 void prepend_to_freelist(FreeRegionList* list); 1266 void decrement_summary_bytes(size_t bytes); 1267 1268 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1269 virtual bool is_in(const void* p) const; 1270 1271 // Return "TRUE" iff the given object address is within the collection 1272 // set. 1273 inline bool obj_in_cs(oop obj); 1274 1275 // Return "TRUE" iff the given object address is in the reserved 1276 // region of g1. 1277 bool is_in_g1_reserved(const void* p) const { 1278 return _g1_reserved.contains(p); 1279 } 1280 1281 // Returns a MemRegion that corresponds to the space that has been 1282 // reserved for the heap 1283 MemRegion g1_reserved() { 1284 return _g1_reserved; 1285 } 1286 1287 // Returns a MemRegion that corresponds to the space that has been 1288 // committed in the heap 1289 MemRegion g1_committed() { 1290 return _g1_committed; 1291 } 1292 1293 virtual bool is_in_closed_subset(const void* p) const; 1294 1295 G1SATBCardTableModRefBS* g1_barrier_set() { 1296 return (G1SATBCardTableModRefBS*) barrier_set(); 1297 } 1298 1299 // This resets the card table to all zeros. It is used after 1300 // a collection pause which used the card table to claim cards. 1301 void cleanUpCardTable(); 1302 1303 // Iteration functions. 1304 1305 // Iterate over all the ref-containing fields of all objects, calling 1306 // "cl.do_oop" on each. 1307 virtual void oop_iterate(ExtendedOopClosure* cl); 1308 1309 // Same as above, restricted to a memory region. 1310 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1311 1312 // Iterate over all objects, calling "cl.do_object" on each. 1313 virtual void object_iterate(ObjectClosure* cl); 1314 1315 virtual void safe_object_iterate(ObjectClosure* cl) { 1316 object_iterate(cl); 1317 } 1318 1319 // Iterate over all spaces in use in the heap, in ascending address order. 1320 virtual void space_iterate(SpaceClosure* cl); 1321 1322 // Iterate over heap regions, in address order, terminating the 1323 // iteration early if the "doHeapRegion" method returns "true". 1324 void heap_region_iterate(HeapRegionClosure* blk) const; 1325 1326 // Return the region with the given index. It assumes the index is valid. 1327 inline HeapRegion* region_at(uint index) const; 1328 1329 // Divide the heap region sequence into "chunks" of some size (the number 1330 // of regions divided by the number of parallel threads times some 1331 // overpartition factor, currently 4). Assumes that this will be called 1332 // in parallel by ParallelGCThreads worker threads with discinct worker 1333 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1334 // calls will use the same "claim_value", and that that claim value is 1335 // different from the claim_value of any heap region before the start of 1336 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1337 // attempting to claim the first region in each chunk, and, if 1338 // successful, applying the closure to each region in the chunk (and 1339 // setting the claim value of the second and subsequent regions of the 1340 // chunk.) For now requires that "doHeapRegion" always returns "false", 1341 // i.e., that a closure never attempt to abort a traversal. 1342 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1343 uint worker, 1344 uint no_of_par_workers, 1345 jint claim_value); 1346 1347 // It resets all the region claim values to the default. 1348 void reset_heap_region_claim_values(); 1349 1350 // Resets the claim values of regions in the current 1351 // collection set to the default. 1352 void reset_cset_heap_region_claim_values(); 1353 1354 #ifdef ASSERT 1355 bool check_heap_region_claim_values(jint claim_value); 1356 1357 // Same as the routine above but only checks regions in the 1358 // current collection set. 1359 bool check_cset_heap_region_claim_values(jint claim_value); 1360 #endif // ASSERT 1361 1362 // Clear the cached cset start regions and (more importantly) 1363 // the time stamps. Called when we reset the GC time stamp. 1364 void clear_cset_start_regions(); 1365 1366 // Given the id of a worker, obtain or calculate a suitable 1367 // starting region for iterating over the current collection set. 1368 HeapRegion* start_cset_region_for_worker(uint worker_i); 1369 1370 // This is a convenience method that is used by the 1371 // HeapRegionIterator classes to calculate the starting region for 1372 // each worker so that they do not all start from the same region. 1373 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1374 1375 // Iterate over the regions (if any) in the current collection set. 1376 void collection_set_iterate(HeapRegionClosure* blk); 1377 1378 // As above but starting from region r 1379 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1380 1381 // Returns the first (lowest address) compactible space in the heap. 1382 virtual CompactibleSpace* first_compactible_space(); 1383 1384 // A CollectedHeap will contain some number of spaces. This finds the 1385 // space containing a given address, or else returns NULL. 1386 virtual Space* space_containing(const void* addr) const; 1387 1388 // A G1CollectedHeap will contain some number of heap regions. This 1389 // finds the region containing a given address, or else returns NULL. 1390 template <class T> 1391 inline HeapRegion* heap_region_containing(const T addr) const; 1392 1393 // Like the above, but requires "addr" to be in the heap (to avoid a 1394 // null-check), and unlike the above, may return an continuing humongous 1395 // region. 1396 template <class T> 1397 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1398 1399 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1400 // each address in the (reserved) heap is a member of exactly 1401 // one block. The defining characteristic of a block is that it is 1402 // possible to find its size, and thus to progress forward to the next 1403 // block. (Blocks may be of different sizes.) Thus, blocks may 1404 // represent Java objects, or they might be free blocks in a 1405 // free-list-based heap (or subheap), as long as the two kinds are 1406 // distinguishable and the size of each is determinable. 1407 1408 // Returns the address of the start of the "block" that contains the 1409 // address "addr". We say "blocks" instead of "object" since some heaps 1410 // may not pack objects densely; a chunk may either be an object or a 1411 // non-object. 1412 virtual HeapWord* block_start(const void* addr) const; 1413 1414 // Requires "addr" to be the start of a chunk, and returns its size. 1415 // "addr + size" is required to be the start of a new chunk, or the end 1416 // of the active area of the heap. 1417 virtual size_t block_size(const HeapWord* addr) const; 1418 1419 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1420 // the block is an object. 1421 virtual bool block_is_obj(const HeapWord* addr) const; 1422 1423 // Does this heap support heap inspection? (+PrintClassHistogram) 1424 virtual bool supports_heap_inspection() const { return true; } 1425 1426 // Section on thread-local allocation buffers (TLABs) 1427 // See CollectedHeap for semantics. 1428 1429 bool supports_tlab_allocation() const; 1430 size_t tlab_capacity(Thread* ignored) const; 1431 size_t tlab_used(Thread* ignored) const; 1432 size_t max_tlab_size() const; 1433 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1434 1435 // Can a compiler initialize a new object without store barriers? 1436 // This permission only extends from the creation of a new object 1437 // via a TLAB up to the first subsequent safepoint. If such permission 1438 // is granted for this heap type, the compiler promises to call 1439 // defer_store_barrier() below on any slow path allocation of 1440 // a new object for which such initializing store barriers will 1441 // have been elided. G1, like CMS, allows this, but should be 1442 // ready to provide a compensating write barrier as necessary 1443 // if that storage came out of a non-young region. The efficiency 1444 // of this implementation depends crucially on being able to 1445 // answer very efficiently in constant time whether a piece of 1446 // storage in the heap comes from a young region or not. 1447 // See ReduceInitialCardMarks. 1448 virtual bool can_elide_tlab_store_barriers() const { 1449 return true; 1450 } 1451 1452 virtual bool card_mark_must_follow_store() const { 1453 return true; 1454 } 1455 1456 inline bool is_in_young(const oop obj); 1457 1458 #ifdef ASSERT 1459 virtual bool is_in_partial_collection(const void* p); 1460 #endif 1461 1462 virtual bool is_scavengable(const void* addr); 1463 1464 // We don't need barriers for initializing stores to objects 1465 // in the young gen: for the SATB pre-barrier, there is no 1466 // pre-value that needs to be remembered; for the remembered-set 1467 // update logging post-barrier, we don't maintain remembered set 1468 // information for young gen objects. 1469 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1470 1471 // Returns "true" iff the given word_size is "very large". 1472 static bool isHumongous(size_t word_size) { 1473 // Note this has to be strictly greater-than as the TLABs 1474 // are capped at the humongous thresold and we want to 1475 // ensure that we don't try to allocate a TLAB as 1476 // humongous and that we don't allocate a humongous 1477 // object in a TLAB. 1478 return word_size > _humongous_object_threshold_in_words; 1479 } 1480 1481 // Update mod union table with the set of dirty cards. 1482 void updateModUnion(); 1483 1484 // Set the mod union bits corresponding to the given memRegion. Note 1485 // that this is always a safe operation, since it doesn't clear any 1486 // bits. 1487 void markModUnionRange(MemRegion mr); 1488 1489 // Records the fact that a marking phase is no longer in progress. 1490 void set_marking_complete() { 1491 _mark_in_progress = false; 1492 } 1493 void set_marking_started() { 1494 _mark_in_progress = true; 1495 } 1496 bool mark_in_progress() { 1497 return _mark_in_progress; 1498 } 1499 1500 // Print the maximum heap capacity. 1501 virtual size_t max_capacity() const; 1502 1503 virtual jlong millis_since_last_gc(); 1504 1505 1506 // Convenience function to be used in situations where the heap type can be 1507 // asserted to be this type. 1508 static G1CollectedHeap* heap(); 1509 1510 void set_region_short_lived_locked(HeapRegion* hr); 1511 // add appropriate methods for any other surv rate groups 1512 1513 YoungList* young_list() const { return _young_list; } 1514 1515 // debugging 1516 bool check_young_list_well_formed() { 1517 return _young_list->check_list_well_formed(); 1518 } 1519 1520 bool check_young_list_empty(bool check_heap, 1521 bool check_sample = true); 1522 1523 // *** Stuff related to concurrent marking. It's not clear to me that so 1524 // many of these need to be public. 1525 1526 // The functions below are helper functions that a subclass of 1527 // "CollectedHeap" can use in the implementation of its virtual 1528 // functions. 1529 // This performs a concurrent marking of the live objects in a 1530 // bitmap off to the side. 1531 void doConcurrentMark(); 1532 1533 bool isMarkedPrev(oop obj) const; 1534 bool isMarkedNext(oop obj) const; 1535 1536 // Determine if an object is dead, given the object and also 1537 // the region to which the object belongs. An object is dead 1538 // iff a) it was not allocated since the last mark and b) it 1539 // is not marked. 1540 1541 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1542 return 1543 !hr->obj_allocated_since_prev_marking(obj) && 1544 !isMarkedPrev(obj); 1545 } 1546 1547 // This function returns true when an object has been 1548 // around since the previous marking and hasn't yet 1549 // been marked during this marking. 1550 1551 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1552 return 1553 !hr->obj_allocated_since_next_marking(obj) && 1554 !isMarkedNext(obj); 1555 } 1556 1557 // Determine if an object is dead, given only the object itself. 1558 // This will find the region to which the object belongs and 1559 // then call the region version of the same function. 1560 1561 // Added if it is NULL it isn't dead. 1562 1563 inline bool is_obj_dead(const oop obj) const; 1564 1565 inline bool is_obj_ill(const oop obj) const; 1566 1567 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1568 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1569 bool is_marked(oop obj, VerifyOption vo); 1570 const char* top_at_mark_start_str(VerifyOption vo); 1571 1572 ConcurrentMark* concurrent_mark() const { return _cm; } 1573 1574 // Refinement 1575 1576 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1577 1578 // The dirty cards region list is used to record a subset of regions 1579 // whose cards need clearing. The list if populated during the 1580 // remembered set scanning and drained during the card table 1581 // cleanup. Although the methods are reentrant, population/draining 1582 // phases must not overlap. For synchronization purposes the last 1583 // element on the list points to itself. 1584 HeapRegion* _dirty_cards_region_list; 1585 void push_dirty_cards_region(HeapRegion* hr); 1586 HeapRegion* pop_dirty_cards_region(); 1587 1588 // Optimized nmethod scanning support routines 1589 1590 // Register the given nmethod with the G1 heap 1591 virtual void register_nmethod(nmethod* nm); 1592 1593 // Unregister the given nmethod from the G1 heap 1594 virtual void unregister_nmethod(nmethod* nm); 1595 1596 // Migrate the nmethods in the code root lists of the regions 1597 // in the collection set to regions in to-space. In the event 1598 // of an evacuation failure, nmethods that reference objects 1599 // that were not successfullly evacuated are not migrated. 1600 void migrate_strong_code_roots(); 1601 1602 // Free up superfluous code root memory. 1603 void purge_code_root_memory(); 1604 1605 // During an initial mark pause, mark all the code roots that 1606 // point into regions *not* in the collection set. 1607 void mark_strong_code_roots(uint worker_id); 1608 1609 // Rebuild the stong code root lists for each region 1610 // after a full GC 1611 void rebuild_strong_code_roots(); 1612 1613 // Delete entries for dead interned string and clean up unreferenced symbols 1614 // in symbol table, possibly in parallel. 1615 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1616 1617 // Redirty logged cards in the refinement queue. 1618 void redirty_logged_cards(); 1619 // Verification 1620 1621 // The following is just to alert the verification code 1622 // that a full collection has occurred and that the 1623 // remembered sets are no longer up to date. 1624 bool _full_collection; 1625 void set_full_collection() { _full_collection = true;} 1626 void clear_full_collection() {_full_collection = false;} 1627 bool full_collection() {return _full_collection;} 1628 1629 // Perform any cleanup actions necessary before allowing a verification. 1630 virtual void prepare_for_verify(); 1631 1632 // Perform verification. 1633 1634 // vo == UsePrevMarking -> use "prev" marking information, 1635 // vo == UseNextMarking -> use "next" marking information 1636 // vo == UseMarkWord -> use the mark word in the object header 1637 // 1638 // NOTE: Only the "prev" marking information is guaranteed to be 1639 // consistent most of the time, so most calls to this should use 1640 // vo == UsePrevMarking. 1641 // Currently, there is only one case where this is called with 1642 // vo == UseNextMarking, which is to verify the "next" marking 1643 // information at the end of remark. 1644 // Currently there is only one place where this is called with 1645 // vo == UseMarkWord, which is to verify the marking during a 1646 // full GC. 1647 void verify(bool silent, VerifyOption vo); 1648 1649 // Override; it uses the "prev" marking information 1650 virtual void verify(bool silent); 1651 1652 // The methods below are here for convenience and dispatch the 1653 // appropriate method depending on value of the given VerifyOption 1654 // parameter. The values for that parameter, and their meanings, 1655 // are the same as those above. 1656 1657 bool is_obj_dead_cond(const oop obj, 1658 const HeapRegion* hr, 1659 const VerifyOption vo) const; 1660 1661 bool is_obj_dead_cond(const oop obj, 1662 const VerifyOption vo) const; 1663 1664 // Printing 1665 1666 virtual void print_on(outputStream* st) const; 1667 virtual void print_extended_on(outputStream* st) const; 1668 virtual void print_on_error(outputStream* st) const; 1669 1670 virtual void print_gc_threads_on(outputStream* st) const; 1671 virtual void gc_threads_do(ThreadClosure* tc) const; 1672 1673 // Override 1674 void print_tracing_info() const; 1675 1676 // The following two methods are helpful for debugging RSet issues. 1677 void print_cset_rsets() PRODUCT_RETURN; 1678 void print_all_rsets() PRODUCT_RETURN; 1679 1680 public: 1681 size_t pending_card_num(); 1682 size_t cards_scanned(); 1683 1684 protected: 1685 size_t _max_heap_capacity; 1686 }; 1687 1688 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1689 private: 1690 bool _retired; 1691 1692 public: 1693 G1ParGCAllocBuffer(size_t gclab_word_size); 1694 virtual ~G1ParGCAllocBuffer() { 1695 guarantee(_retired, "Allocation buffer has not been retired"); 1696 } 1697 1698 virtual void set_buf(HeapWord* buf) { 1699 ParGCAllocBuffer::set_buf(buf); 1700 _retired = false; 1701 } 1702 1703 virtual void retire(bool end_of_gc, bool retain) { 1704 if (_retired) { 1705 return; 1706 } 1707 ParGCAllocBuffer::retire(end_of_gc, retain); 1708 _retired = true; 1709 } 1710 }; 1711 1712 class G1ParScanThreadState : public StackObj { 1713 protected: 1714 G1CollectedHeap* _g1h; 1715 RefToScanQueue* _refs; 1716 DirtyCardQueue _dcq; 1717 G1SATBCardTableModRefBS* _ct_bs; 1718 G1RemSet* _g1_rem; 1719 1720 G1ParGCAllocBuffer _surviving_alloc_buffer; 1721 G1ParGCAllocBuffer _tenured_alloc_buffer; 1722 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount]; 1723 ageTable _age_table; 1724 1725 G1ParScanClosure _scanner; 1726 1727 size_t _alloc_buffer_waste; 1728 size_t _undo_waste; 1729 1730 OopsInHeapRegionClosure* _evac_failure_cl; 1731 1732 int _hash_seed; 1733 uint _queue_num; 1734 1735 size_t _term_attempts; 1736 1737 double _start; 1738 double _start_strong_roots; 1739 double _strong_roots_time; 1740 double _start_term; 1741 double _term_time; 1742 1743 // Map from young-age-index (0 == not young, 1 is youngest) to 1744 // surviving words. base is what we get back from the malloc call 1745 size_t* _surviving_young_words_base; 1746 // this points into the array, as we use the first few entries for padding 1747 size_t* _surviving_young_words; 1748 1749 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1750 1751 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1752 1753 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1754 1755 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1756 G1SATBCardTableModRefBS* ctbs() { return _ct_bs; } 1757 1758 template <class T> inline void immediate_rs_update(HeapRegion* from, T* p, int tid); 1759 1760 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1761 // If the new value of the field points to the same region or 1762 // is the to-space, we don't need to include it in the Rset updates. 1763 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1764 size_t card_index = ctbs()->index_for(p); 1765 // If the card hasn't been added to the buffer, do it. 1766 if (ctbs()->mark_card_deferred(card_index)) { 1767 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1768 } 1769 } 1770 } 1771 1772 public: 1773 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp); 1774 1775 ~G1ParScanThreadState() { 1776 retire_alloc_buffers(); 1777 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1778 } 1779 1780 RefToScanQueue* refs() { return _refs; } 1781 ageTable* age_table() { return &_age_table; } 1782 1783 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) { 1784 return _alloc_buffers[purpose]; 1785 } 1786 1787 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1788 size_t undo_waste() const { return _undo_waste; } 1789 1790 #ifdef ASSERT 1791 bool verify_ref(narrowOop* ref) const; 1792 bool verify_ref(oop* ref) const; 1793 bool verify_task(StarTask ref) const; 1794 #endif // ASSERT 1795 1796 template <class T> void push_on_queue(T* ref) { 1797 assert(verify_ref(ref), "sanity"); 1798 refs()->push(ref); 1799 } 1800 1801 template <class T> inline void update_rs(HeapRegion* from, T* p, int tid); 1802 1803 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1804 HeapWord* obj = NULL; 1805 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1806 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1807 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose); 1808 add_to_alloc_buffer_waste(alloc_buf->words_remaining()); 1809 alloc_buf->retire(false /* end_of_gc */, false /* retain */); 1810 1811 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1812 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1813 // Otherwise. 1814 alloc_buf->set_word_size(gclab_word_size); 1815 alloc_buf->set_buf(buf); 1816 1817 obj = alloc_buf->allocate(word_sz); 1818 assert(obj != NULL, "buffer was definitely big enough..."); 1819 } else { 1820 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1821 } 1822 return obj; 1823 } 1824 1825 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1826 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1827 if (obj != NULL) return obj; 1828 return allocate_slow(purpose, word_sz); 1829 } 1830 1831 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1832 if (alloc_buffer(purpose)->contains(obj)) { 1833 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 1834 "should contain whole object"); 1835 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 1836 } else { 1837 CollectedHeap::fill_with_object(obj, word_sz); 1838 add_to_undo_waste(word_sz); 1839 } 1840 } 1841 1842 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 1843 _evac_failure_cl = evac_failure_cl; 1844 } 1845 OopsInHeapRegionClosure* evac_failure_closure() { 1846 return _evac_failure_cl; 1847 } 1848 1849 int* hash_seed() { return &_hash_seed; } 1850 uint queue_num() { return _queue_num; } 1851 1852 size_t term_attempts() const { return _term_attempts; } 1853 void note_term_attempt() { _term_attempts++; } 1854 1855 void start_strong_roots() { 1856 _start_strong_roots = os::elapsedTime(); 1857 } 1858 void end_strong_roots() { 1859 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 1860 } 1861 double strong_roots_time() const { return _strong_roots_time; } 1862 1863 void start_term_time() { 1864 note_term_attempt(); 1865 _start_term = os::elapsedTime(); 1866 } 1867 void end_term_time() { 1868 _term_time += (os::elapsedTime() - _start_term); 1869 } 1870 double term_time() const { return _term_time; } 1871 1872 double elapsed_time() const { 1873 return os::elapsedTime() - _start; 1874 } 1875 1876 static void 1877 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 1878 void 1879 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 1880 1881 size_t* surviving_young_words() { 1882 // We add on to hide entry 0 which accumulates surviving words for 1883 // age -1 regions (i.e. non-young ones) 1884 return _surviving_young_words; 1885 } 1886 1887 private: 1888 void retire_alloc_buffers() { 1889 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 1890 size_t waste = _alloc_buffers[ap]->words_remaining(); 1891 add_to_alloc_buffer_waste(waste); 1892 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 1893 true /* end_of_gc */, 1894 false /* retain */); 1895 } 1896 } 1897 1898 #define G1_PARTIAL_ARRAY_MASK 0x2 1899 1900 inline bool has_partial_array_mask(oop* ref) const { 1901 return ((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) == G1_PARTIAL_ARRAY_MASK; 1902 } 1903 1904 // We never encode partial array oops as narrowOop*, so return false immediately. 1905 // This allows the compiler to create optimized code when popping references from 1906 // the work queue. 1907 inline bool has_partial_array_mask(narrowOop* ref) const { 1908 assert(((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) != G1_PARTIAL_ARRAY_MASK, "Partial array oop reference encoded as narrowOop*"); 1909 return false; 1910 } 1911 1912 // Only implement set_partial_array_mask() for regular oops, not for narrowOops. 1913 // We always encode partial arrays as regular oop, to allow the 1914 // specialization for has_partial_array_mask() for narrowOops above. 1915 // This means that unintentional use of this method with narrowOops are caught 1916 // by the compiler. 1917 inline oop* set_partial_array_mask(oop obj) const { 1918 assert(((uintptr_t)(void *)obj & G1_PARTIAL_ARRAY_MASK) == 0, "Information loss!"); 1919 return (oop*) ((uintptr_t)(void *)obj | G1_PARTIAL_ARRAY_MASK); 1920 } 1921 1922 inline oop clear_partial_array_mask(oop* ref) const { 1923 return cast_to_oop((intptr_t)ref & ~G1_PARTIAL_ARRAY_MASK); 1924 } 1925 1926 inline void do_oop_partial_array(oop* p); 1927 1928 // This method is applied to the fields of the objects that have just been copied. 1929 template <class T> void do_oop_evac(T* p, HeapRegion* from) { 1930 assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)), 1931 "Reference should not be NULL here as such are never pushed to the task queue."); 1932 oop obj = oopDesc::load_decode_heap_oop_not_null(p); 1933 1934 // Although we never intentionally push references outside of the collection 1935 // set, due to (benign) races in the claim mechanism during RSet scanning more 1936 // than one thread might claim the same card. So the same card may be 1937 // processed multiple times. So redo this check. 1938 if (_g1h->in_cset_fast_test(obj)) { 1939 oop forwardee; 1940 if (obj->is_forwarded()) { 1941 forwardee = obj->forwardee(); 1942 } else { 1943 forwardee = copy_to_survivor_space(obj); 1944 } 1945 assert(forwardee != NULL, "forwardee should not be NULL"); 1946 oopDesc::encode_store_heap_oop(p, forwardee); 1947 } 1948 1949 assert(obj != NULL, "Must be"); 1950 update_rs(from, p, queue_num()); 1951 } 1952 public: 1953 1954 oop copy_to_survivor_space(oop const obj); 1955 1956 template <class T> inline void deal_with_reference(T* ref_to_scan); 1957 1958 inline void deal_with_reference(StarTask ref); 1959 1960 public: 1961 void trim_queue(); 1962 }; 1963 1964 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP