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/g1SATBCardTableModRefBS.hpp" 35 #include "gc_implementation/g1/g1YCTypes.hpp" 36 #include "gc_implementation/g1/heapRegionSeq.hpp" 37 #include "gc_implementation/g1/heapRegionSet.hpp" 38 #include "gc_implementation/shared/hSpaceCounters.hpp" 39 #include "gc_implementation/shared/parGCAllocBuffer.hpp" 40 #include "memory/barrierSet.hpp" 41 #include "memory/memRegion.hpp" 42 #include "memory/sharedHeap.hpp" 43 #include "utilities/stack.hpp" 44 45 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 46 // It uses the "Garbage First" heap organization and algorithm, which 47 // may combine concurrent marking with parallel, incremental compaction of 48 // heap subsets that will yield large amounts of garbage. 49 50 // Forward declarations 51 class HeapRegion; 52 class HRRSCleanupTask; 53 class GenerationSpec; 54 class OopsInHeapRegionClosure; 55 class G1KlassScanClosure; 56 class G1ScanHeapEvacClosure; 57 class ObjectClosure; 58 class SpaceClosure; 59 class CompactibleSpaceClosure; 60 class Space; 61 class G1CollectorPolicy; 62 class GenRemSet; 63 class G1RemSet; 64 class HeapRegionRemSetIterator; 65 class ConcurrentMark; 66 class ConcurrentMarkThread; 67 class ConcurrentG1Refine; 68 class ConcurrentGCTimer; 69 class GenerationCounters; 70 class STWGCTimer; 71 class G1NewTracer; 72 class G1OldTracer; 73 class EvacuationFailedInfo; 74 class nmethod; 75 class Ticks; 76 77 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 78 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 79 80 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 81 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 82 83 enum GCAllocPurpose { 84 GCAllocForTenured, 85 GCAllocForSurvived, 86 GCAllocPurposeCount 87 }; 88 89 class YoungList : public CHeapObj<mtGC> { 90 private: 91 G1CollectedHeap* _g1h; 92 93 HeapRegion* _head; 94 95 HeapRegion* _survivor_head; 96 HeapRegion* _survivor_tail; 97 98 HeapRegion* _curr; 99 100 uint _length; 101 uint _survivor_length; 102 103 size_t _last_sampled_rs_lengths; 104 size_t _sampled_rs_lengths; 105 106 void empty_list(HeapRegion* list); 107 108 public: 109 YoungList(G1CollectedHeap* g1h); 110 111 void push_region(HeapRegion* hr); 112 void add_survivor_region(HeapRegion* hr); 113 114 void empty_list(); 115 bool is_empty() { return _length == 0; } 116 uint length() { return _length; } 117 uint survivor_length() { return _survivor_length; } 118 119 // Currently we do not keep track of the used byte sum for the 120 // young list and the survivors and it'd be quite a lot of work to 121 // do so. When we'll eventually replace the young list with 122 // instances of HeapRegionLinkedList we'll get that for free. So, 123 // we'll report the more accurate information then. 124 size_t eden_used_bytes() { 125 assert(length() >= survivor_length(), "invariant"); 126 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 127 } 128 size_t survivor_used_bytes() { 129 return (size_t) survivor_length() * HeapRegion::GrainBytes; 130 } 131 132 void rs_length_sampling_init(); 133 bool rs_length_sampling_more(); 134 void rs_length_sampling_next(); 135 136 void reset_sampled_info() { 137 _last_sampled_rs_lengths = 0; 138 } 139 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 140 141 // for development purposes 142 void reset_auxilary_lists(); 143 void clear() { _head = NULL; _length = 0; } 144 145 void clear_survivors() { 146 _survivor_head = NULL; 147 _survivor_tail = NULL; 148 _survivor_length = 0; 149 } 150 151 HeapRegion* first_region() { return _head; } 152 HeapRegion* first_survivor_region() { return _survivor_head; } 153 HeapRegion* last_survivor_region() { return _survivor_tail; } 154 155 // debugging 156 bool check_list_well_formed(); 157 bool check_list_empty(bool check_sample = true); 158 void print(); 159 }; 160 161 class MutatorAllocRegion : public G1AllocRegion { 162 protected: 163 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 164 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 165 public: 166 MutatorAllocRegion() 167 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 168 }; 169 170 class SurvivorGCAllocRegion : public G1AllocRegion { 171 protected: 172 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 173 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 174 public: 175 SurvivorGCAllocRegion() 176 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { } 177 }; 178 179 class OldGCAllocRegion : public G1AllocRegion { 180 protected: 181 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 182 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 183 public: 184 OldGCAllocRegion() 185 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { } 186 }; 187 188 // The G1 STW is alive closure. 189 // An instance is embedded into the G1CH and used as the 190 // (optional) _is_alive_non_header closure in the STW 191 // reference processor. It is also extensively used during 192 // reference processing during STW evacuation pauses. 193 class G1STWIsAliveClosure: public BoolObjectClosure { 194 G1CollectedHeap* _g1; 195 public: 196 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 197 bool do_object_b(oop p); 198 }; 199 200 // Instances of this class are used for quick tests on whether a reference points 201 // into the collection set. Each of the array's elements denotes whether the 202 // corresponding region is in the collection set. 203 class G1FastCSetBiasedMappedArray : public G1BiasedMappedArray<bool> { 204 protected: 205 bool default_value() const { return false; } 206 public: 207 void clear() { G1BiasedMappedArray<bool>::clear(); } 208 }; 209 210 class RefineCardTableEntryClosure; 211 212 class G1CollectedHeap : public SharedHeap { 213 friend class VM_G1CollectForAllocation; 214 friend class VM_G1CollectFull; 215 friend class VM_G1IncCollectionPause; 216 friend class VMStructs; 217 friend class MutatorAllocRegion; 218 friend class SurvivorGCAllocRegion; 219 friend class OldGCAllocRegion; 220 221 // Closures used in implementation. 222 template <G1Barrier barrier, bool do_mark_object> 223 friend class G1ParCopyClosure; 224 friend class G1IsAliveClosure; 225 friend class G1EvacuateFollowersClosure; 226 friend class G1ParScanThreadState; 227 friend class G1ParScanClosureSuper; 228 friend class G1ParEvacuateFollowersClosure; 229 friend class G1ParTask; 230 friend class G1FreeGarbageRegionClosure; 231 friend class RefineCardTableEntryClosure; 232 friend class G1PrepareCompactClosure; 233 friend class RegionSorter; 234 friend class RegionResetter; 235 friend class CountRCClosure; 236 friend class EvacPopObjClosure; 237 friend class G1ParCleanupCTTask; 238 239 // Other related classes. 240 friend class G1MarkSweep; 241 242 private: 243 // The one and only G1CollectedHeap, so static functions can find it. 244 static G1CollectedHeap* _g1h; 245 246 static size_t _humongous_object_threshold_in_words; 247 248 // Storage for the G1 heap. 249 VirtualSpace _g1_storage; 250 MemRegion _g1_reserved; 251 252 // The part of _g1_storage that is currently committed. 253 MemRegion _g1_committed; 254 255 // The master free list. It will satisfy all new region allocations. 256 FreeRegionList _free_list; 257 258 // The secondary free list which contains regions that have been 259 // freed up during the cleanup process. This will be appended to the 260 // master free list when appropriate. 261 FreeRegionList _secondary_free_list; 262 263 // It keeps track of the old regions. 264 HeapRegionSet _old_set; 265 266 // It keeps track of the humongous regions. 267 HeapRegionSet _humongous_set; 268 269 // The number of regions we could create by expansion. 270 uint _expansion_regions; 271 272 // The block offset table for the G1 heap. 273 G1BlockOffsetSharedArray* _bot_shared; 274 275 // Tears down the region sets / lists so that they are empty and the 276 // regions on the heap do not belong to a region set / list. The 277 // only exception is the humongous set which we leave unaltered. If 278 // free_list_only is true, it will only tear down the master free 279 // list. It is called before a Full GC (free_list_only == false) or 280 // before heap shrinking (free_list_only == true). 281 void tear_down_region_sets(bool free_list_only); 282 283 // Rebuilds the region sets / lists so that they are repopulated to 284 // reflect the contents of the heap. The only exception is the 285 // humongous set which was not torn down in the first place. If 286 // free_list_only is true, it will only rebuild the master free 287 // list. It is called after a Full GC (free_list_only == false) or 288 // after heap shrinking (free_list_only == true). 289 void rebuild_region_sets(bool free_list_only); 290 291 // The sequence of all heap regions in the heap. 292 HeapRegionSeq _hrs; 293 294 // Alloc region used to satisfy mutator allocation requests. 295 MutatorAllocRegion _mutator_alloc_region; 296 297 // Alloc region used to satisfy allocation requests by the GC for 298 // survivor objects. 299 SurvivorGCAllocRegion _survivor_gc_alloc_region; 300 301 // PLAB sizing policy for survivors. 302 PLABStats _survivor_plab_stats; 303 304 // Alloc region used to satisfy allocation requests by the GC for 305 // old objects. 306 OldGCAllocRegion _old_gc_alloc_region; 307 308 // PLAB sizing policy for tenured objects. 309 PLABStats _old_plab_stats; 310 311 PLABStats* stats_for_purpose(GCAllocPurpose purpose) { 312 PLABStats* stats = NULL; 313 314 switch (purpose) { 315 case GCAllocForSurvived: 316 stats = &_survivor_plab_stats; 317 break; 318 case GCAllocForTenured: 319 stats = &_old_plab_stats; 320 break; 321 default: 322 assert(false, "unrecognized GCAllocPurpose"); 323 } 324 325 return stats; 326 } 327 328 // The last old region we allocated to during the last GC. 329 // Typically, it is not full so we should re-use it during the next GC. 330 HeapRegion* _retained_old_gc_alloc_region; 331 332 // It specifies whether we should attempt to expand the heap after a 333 // region allocation failure. If heap expansion fails we set this to 334 // false so that we don't re-attempt the heap expansion (it's likely 335 // that subsequent expansion attempts will also fail if one fails). 336 // Currently, it is only consulted during GC and it's reset at the 337 // start of each GC. 338 bool _expand_heap_after_alloc_failure; 339 340 // It resets the mutator alloc region before new allocations can take place. 341 void init_mutator_alloc_region(); 342 343 // It releases the mutator alloc region. 344 void release_mutator_alloc_region(); 345 346 // It initializes the GC alloc regions at the start of a GC. 347 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 348 349 // It releases the GC alloc regions at the end of a GC. 350 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 351 352 // It does any cleanup that needs to be done on the GC alloc regions 353 // before a Full GC. 354 void abandon_gc_alloc_regions(); 355 356 // Helper for monitoring and management support. 357 G1MonitoringSupport* _g1mm; 358 359 // Determines PLAB size for a particular allocation purpose. 360 size_t desired_plab_sz(GCAllocPurpose purpose); 361 362 // Outside of GC pauses, the number of bytes used in all regions other 363 // than the current allocation region. 364 size_t _summary_bytes_used; 365 366 // This array is used for a quick test on whether a reference points into 367 // the collection set or not. Each of the array's elements denotes whether the 368 // corresponding region is in the collection set or not. 369 G1FastCSetBiasedMappedArray _in_cset_fast_test; 370 371 volatile unsigned _gc_time_stamp; 372 373 size_t* _surviving_young_words; 374 375 G1HRPrinter _hr_printer; 376 377 void setup_surviving_young_words(); 378 void update_surviving_young_words(size_t* surv_young_words); 379 void cleanup_surviving_young_words(); 380 381 // It decides whether an explicit GC should start a concurrent cycle 382 // instead of doing a STW GC. Currently, a concurrent cycle is 383 // explicitly started if: 384 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 385 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 386 // (c) cause == _g1_humongous_allocation 387 bool should_do_concurrent_full_gc(GCCause::Cause cause); 388 389 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 390 // concurrent cycles) we have started. 391 volatile unsigned int _old_marking_cycles_started; 392 393 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 394 // concurrent cycles) we have completed. 395 volatile unsigned int _old_marking_cycles_completed; 396 397 bool _concurrent_cycle_started; 398 399 // This is a non-product method that is helpful for testing. It is 400 // called at the end of a GC and artificially expands the heap by 401 // allocating a number of dead regions. This way we can induce very 402 // frequent marking cycles and stress the cleanup / concurrent 403 // cleanup code more (as all the regions that will be allocated by 404 // this method will be found dead by the marking cycle). 405 void allocate_dummy_regions() PRODUCT_RETURN; 406 407 // Clear RSets after a compaction. It also resets the GC time stamps. 408 void clear_rsets_post_compaction(); 409 410 // If the HR printer is active, dump the state of the regions in the 411 // heap after a compaction. 412 void print_hrs_post_compaction(); 413 414 double verify(bool guard, const char* msg); 415 void verify_before_gc(); 416 void verify_after_gc(); 417 418 void log_gc_header(); 419 void log_gc_footer(double pause_time_sec); 420 421 // These are macros so that, if the assert fires, we get the correct 422 // line number, file, etc. 423 424 #define heap_locking_asserts_err_msg(_extra_message_) \ 425 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 426 (_extra_message_), \ 427 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 428 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 429 BOOL_TO_STR(Thread::current()->is_VM_thread())) 430 431 #define assert_heap_locked() \ 432 do { \ 433 assert(Heap_lock->owned_by_self(), \ 434 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 435 } while (0) 436 437 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 438 do { \ 439 assert(Heap_lock->owned_by_self() || \ 440 (SafepointSynchronize::is_at_safepoint() && \ 441 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 442 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 443 "should be at a safepoint")); \ 444 } while (0) 445 446 #define assert_heap_locked_and_not_at_safepoint() \ 447 do { \ 448 assert(Heap_lock->owned_by_self() && \ 449 !SafepointSynchronize::is_at_safepoint(), \ 450 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 451 "should not be at a safepoint")); \ 452 } while (0) 453 454 #define assert_heap_not_locked() \ 455 do { \ 456 assert(!Heap_lock->owned_by_self(), \ 457 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 458 } while (0) 459 460 #define assert_heap_not_locked_and_not_at_safepoint() \ 461 do { \ 462 assert(!Heap_lock->owned_by_self() && \ 463 !SafepointSynchronize::is_at_safepoint(), \ 464 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 465 "should not be at a safepoint")); \ 466 } while (0) 467 468 #define assert_at_safepoint(_should_be_vm_thread_) \ 469 do { \ 470 assert(SafepointSynchronize::is_at_safepoint() && \ 471 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 472 heap_locking_asserts_err_msg("should be at a safepoint")); \ 473 } while (0) 474 475 #define assert_not_at_safepoint() \ 476 do { \ 477 assert(!SafepointSynchronize::is_at_safepoint(), \ 478 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 479 } while (0) 480 481 protected: 482 483 // The young region list. 484 YoungList* _young_list; 485 486 // The current policy object for the collector. 487 G1CollectorPolicy* _g1_policy; 488 489 // This is the second level of trying to allocate a new region. If 490 // new_region() didn't find a region on the free_list, this call will 491 // check whether there's anything available on the 492 // secondary_free_list and/or wait for more regions to appear on 493 // that list, if _free_regions_coming is set. 494 HeapRegion* new_region_try_secondary_free_list(bool is_old); 495 496 // Try to allocate a single non-humongous HeapRegion sufficient for 497 // an allocation of the given word_size. If do_expand is true, 498 // attempt to expand the heap if necessary to satisfy the allocation 499 // request. If the region is to be used as an old region or for a 500 // humongous object, set is_old to true. If not, to false. 501 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 502 503 // Attempt to satisfy a humongous allocation request of the given 504 // size by finding a contiguous set of free regions of num_regions 505 // length and remove them from the master free list. Return the 506 // index of the first region or G1_NULL_HRS_INDEX if the search 507 // was unsuccessful. 508 uint humongous_obj_allocate_find_first(uint num_regions, 509 size_t word_size); 510 511 // Initialize a contiguous set of free regions of length num_regions 512 // and starting at index first so that they appear as a single 513 // humongous region. 514 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 515 uint num_regions, 516 size_t word_size); 517 518 // Attempt to allocate a humongous object of the given size. Return 519 // NULL if unsuccessful. 520 HeapWord* humongous_obj_allocate(size_t word_size); 521 522 // The following two methods, allocate_new_tlab() and 523 // mem_allocate(), are the two main entry points from the runtime 524 // into the G1's allocation routines. They have the following 525 // assumptions: 526 // 527 // * They should both be called outside safepoints. 528 // 529 // * They should both be called without holding the Heap_lock. 530 // 531 // * All allocation requests for new TLABs should go to 532 // allocate_new_tlab(). 533 // 534 // * All non-TLAB allocation requests should go to mem_allocate(). 535 // 536 // * If either call cannot satisfy the allocation request using the 537 // current allocating region, they will try to get a new one. If 538 // this fails, they will attempt to do an evacuation pause and 539 // retry the allocation. 540 // 541 // * If all allocation attempts fail, even after trying to schedule 542 // an evacuation pause, allocate_new_tlab() will return NULL, 543 // whereas mem_allocate() will attempt a heap expansion and/or 544 // schedule a Full GC. 545 // 546 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 547 // should never be called with word_size being humongous. All 548 // humongous allocation requests should go to mem_allocate() which 549 // will satisfy them with a special path. 550 551 virtual HeapWord* allocate_new_tlab(size_t word_size); 552 553 virtual HeapWord* mem_allocate(size_t word_size, 554 bool* gc_overhead_limit_was_exceeded); 555 556 // The following three methods take a gc_count_before_ret 557 // parameter which is used to return the GC count if the method 558 // returns NULL. Given that we are required to read the GC count 559 // while holding the Heap_lock, and these paths will take the 560 // Heap_lock at some point, it's easier to get them to read the GC 561 // count while holding the Heap_lock before they return NULL instead 562 // of the caller (namely: mem_allocate()) having to also take the 563 // Heap_lock just to read the GC count. 564 565 // First-level mutator allocation attempt: try to allocate out of 566 // the mutator alloc region without taking the Heap_lock. This 567 // should only be used for non-humongous allocations. 568 inline HeapWord* attempt_allocation(size_t word_size, 569 unsigned int* gc_count_before_ret, 570 int* gclocker_retry_count_ret); 571 572 // Second-level mutator allocation attempt: take the Heap_lock and 573 // retry the allocation attempt, potentially scheduling a GC 574 // pause. This should only be used for non-humongous allocations. 575 HeapWord* attempt_allocation_slow(size_t word_size, 576 unsigned int* gc_count_before_ret, 577 int* gclocker_retry_count_ret); 578 579 // Takes the Heap_lock and attempts a humongous allocation. It can 580 // potentially schedule a GC pause. 581 HeapWord* attempt_allocation_humongous(size_t word_size, 582 unsigned int* gc_count_before_ret, 583 int* gclocker_retry_count_ret); 584 585 // Allocation attempt that should be called during safepoints (e.g., 586 // at the end of a successful GC). expect_null_mutator_alloc_region 587 // specifies whether the mutator alloc region is expected to be NULL 588 // or not. 589 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 590 bool expect_null_mutator_alloc_region); 591 592 // It dirties the cards that cover the block so that so that the post 593 // write barrier never queues anything when updating objects on this 594 // block. It is assumed (and in fact we assert) that the block 595 // belongs to a young region. 596 inline void dirty_young_block(HeapWord* start, size_t word_size); 597 598 // Allocate blocks during garbage collection. Will ensure an 599 // allocation region, either by picking one or expanding the 600 // heap, and then allocate a block of the given size. The block 601 // may not be a humongous - it must fit into a single heap region. 602 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 603 604 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 605 HeapRegion* alloc_region, 606 bool par, 607 size_t word_size); 608 609 // Ensure that no further allocations can happen in "r", bearing in mind 610 // that parallel threads might be attempting allocations. 611 void par_allocate_remaining_space(HeapRegion* r); 612 613 // Allocation attempt during GC for a survivor object / PLAB. 614 inline HeapWord* survivor_attempt_allocation(size_t word_size); 615 616 // Allocation attempt during GC for an old object / PLAB. 617 inline HeapWord* old_attempt_allocation(size_t word_size); 618 619 // These methods are the "callbacks" from the G1AllocRegion class. 620 621 // For mutator alloc regions. 622 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 623 void retire_mutator_alloc_region(HeapRegion* alloc_region, 624 size_t allocated_bytes); 625 626 // For GC alloc regions. 627 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 628 GCAllocPurpose ap); 629 void retire_gc_alloc_region(HeapRegion* alloc_region, 630 size_t allocated_bytes, GCAllocPurpose ap); 631 632 // - if explicit_gc is true, the GC is for a System.gc() or a heap 633 // inspection request and should collect the entire heap 634 // - if clear_all_soft_refs is true, all soft references should be 635 // cleared during the GC 636 // - if explicit_gc is false, word_size describes the allocation that 637 // the GC should attempt (at least) to satisfy 638 // - it returns false if it is unable to do the collection due to the 639 // GC locker being active, true otherwise 640 bool do_collection(bool explicit_gc, 641 bool clear_all_soft_refs, 642 size_t word_size); 643 644 // Callback from VM_G1CollectFull operation. 645 // Perform a full collection. 646 virtual void do_full_collection(bool clear_all_soft_refs); 647 648 // Resize the heap if necessary after a full collection. If this is 649 // after a collect-for allocation, "word_size" is the allocation size, 650 // and will be considered part of the used portion of the heap. 651 void resize_if_necessary_after_full_collection(size_t word_size); 652 653 // Callback from VM_G1CollectForAllocation operation. 654 // This function does everything necessary/possible to satisfy a 655 // failed allocation request (including collection, expansion, etc.) 656 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 657 658 // Attempting to expand the heap sufficiently 659 // to support an allocation of the given "word_size". If 660 // successful, perform the allocation and return the address of the 661 // allocated block, or else "NULL". 662 HeapWord* expand_and_allocate(size_t word_size); 663 664 // Process any reference objects discovered during 665 // an incremental evacuation pause. 666 void process_discovered_references(uint no_of_gc_workers); 667 668 // Enqueue any remaining discovered references 669 // after processing. 670 void enqueue_discovered_references(uint no_of_gc_workers); 671 672 public: 673 674 G1MonitoringSupport* g1mm() { 675 assert(_g1mm != NULL, "should have been initialized"); 676 return _g1mm; 677 } 678 679 // Expand the garbage-first heap by at least the given size (in bytes!). 680 // Returns true if the heap was expanded by the requested amount; 681 // false otherwise. 682 // (Rounds up to a HeapRegion boundary.) 683 bool expand(size_t expand_bytes); 684 685 // Do anything common to GC's. 686 virtual void gc_prologue(bool full); 687 virtual void gc_epilogue(bool full); 688 689 // We register a region with the fast "in collection set" test. We 690 // simply set to true the array slot corresponding to this region. 691 void register_region_with_in_cset_fast_test(HeapRegion* r) { 692 _in_cset_fast_test.set_by_index(r->hrs_index(), true); 693 } 694 695 // This is a fast test on whether a reference points into the 696 // collection set or not. Assume that the reference 697 // points into the heap. 698 inline bool in_cset_fast_test(oop obj); 699 700 void clear_cset_fast_test() { 701 _in_cset_fast_test.clear(); 702 } 703 704 // This is called at the start of either a concurrent cycle or a Full 705 // GC to update the number of old marking cycles started. 706 void increment_old_marking_cycles_started(); 707 708 // This is called at the end of either a concurrent cycle or a Full 709 // GC to update the number of old marking cycles completed. Those two 710 // can happen in a nested fashion, i.e., we start a concurrent 711 // cycle, a Full GC happens half-way through it which ends first, 712 // and then the cycle notices that a Full GC happened and ends 713 // too. The concurrent parameter is a boolean to help us do a bit 714 // tighter consistency checking in the method. If concurrent is 715 // false, the caller is the inner caller in the nesting (i.e., the 716 // Full GC). If concurrent is true, the caller is the outer caller 717 // in this nesting (i.e., the concurrent cycle). Further nesting is 718 // not currently supported. The end of this call also notifies 719 // the FullGCCount_lock in case a Java thread is waiting for a full 720 // GC to happen (e.g., it called System.gc() with 721 // +ExplicitGCInvokesConcurrent). 722 void increment_old_marking_cycles_completed(bool concurrent); 723 724 unsigned int old_marking_cycles_completed() { 725 return _old_marking_cycles_completed; 726 } 727 728 void register_concurrent_cycle_start(const Ticks& start_time); 729 void register_concurrent_cycle_end(); 730 void trace_heap_after_concurrent_cycle(); 731 732 G1YCType yc_type(); 733 734 G1HRPrinter* hr_printer() { return &_hr_printer; } 735 736 // Frees a non-humongous region by initializing its contents and 737 // adding it to the free list that's passed as a parameter (this is 738 // usually a local list which will be appended to the master free 739 // list later). The used bytes of freed regions are accumulated in 740 // pre_used. If par is true, the region's RSet will not be freed 741 // up. The assumption is that this will be done later. 742 // The locked parameter indicates if the caller has already taken 743 // care of proper synchronization. This may allow some optimizations. 744 void free_region(HeapRegion* hr, 745 FreeRegionList* free_list, 746 bool par, 747 bool locked = false); 748 749 // Frees a humongous region by collapsing it into individual regions 750 // and calling free_region() for each of them. The freed regions 751 // will be added to the free list that's passed as a parameter (this 752 // is usually a local list which will be appended to the master free 753 // list later). The used bytes of freed regions are accumulated in 754 // pre_used. If par is true, the region's RSet will not be freed 755 // up. The assumption is that this will be done later. 756 void free_humongous_region(HeapRegion* hr, 757 FreeRegionList* free_list, 758 bool par); 759 protected: 760 761 // Shrink the garbage-first heap by at most the given size (in bytes!). 762 // (Rounds down to a HeapRegion boundary.) 763 virtual void shrink(size_t expand_bytes); 764 void shrink_helper(size_t expand_bytes); 765 766 #if TASKQUEUE_STATS 767 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 768 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 769 void reset_taskqueue_stats(); 770 #endif // TASKQUEUE_STATS 771 772 // Schedule the VM operation that will do an evacuation pause to 773 // satisfy an allocation request of word_size. *succeeded will 774 // return whether the VM operation was successful (it did do an 775 // evacuation pause) or not (another thread beat us to it or the GC 776 // locker was active). Given that we should not be holding the 777 // Heap_lock when we enter this method, we will pass the 778 // gc_count_before (i.e., total_collections()) as a parameter since 779 // it has to be read while holding the Heap_lock. Currently, both 780 // methods that call do_collection_pause() release the Heap_lock 781 // before the call, so it's easy to read gc_count_before just before. 782 HeapWord* do_collection_pause(size_t word_size, 783 unsigned int gc_count_before, 784 bool* succeeded, 785 GCCause::Cause gc_cause); 786 787 // The guts of the incremental collection pause, executed by the vm 788 // thread. It returns false if it is unable to do the collection due 789 // to the GC locker being active, true otherwise 790 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 791 792 // Actually do the work of evacuating the collection set. 793 void evacuate_collection_set(EvacuationInfo& evacuation_info); 794 795 // The g1 remembered set of the heap. 796 G1RemSet* _g1_rem_set; 797 798 // A set of cards that cover the objects for which the Rsets should be updated 799 // concurrently after the collection. 800 DirtyCardQueueSet _dirty_card_queue_set; 801 802 // The closure used to refine a single card. 803 RefineCardTableEntryClosure* _refine_cte_cl; 804 805 // A function to check the consistency of dirty card logs. 806 void check_ct_logs_at_safepoint(); 807 808 // A DirtyCardQueueSet that is used to hold cards that contain 809 // references into the current collection set. This is used to 810 // update the remembered sets of the regions in the collection 811 // set in the event of an evacuation failure. 812 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 813 814 // After a collection pause, make the regions in the CS into free 815 // regions. 816 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 817 818 // Abandon the current collection set without recording policy 819 // statistics or updating free lists. 820 void abandon_collection_set(HeapRegion* cs_head); 821 822 // Applies "scan_non_heap_roots" to roots outside the heap, 823 // "scan_rs" to roots inside the heap (having done "set_region" to 824 // indicate the region in which the root resides), 825 // and does "scan_metadata" If "scan_rs" is 826 // NULL, then this step is skipped. The "worker_i" 827 // param is for use with parallel roots processing, and should be 828 // the "i" of the calling parallel worker thread's work(i) function. 829 // In the sequential case this param will be ignored. 830 void g1_process_strong_roots(bool is_scavenging, 831 ScanningOption so, 832 OopClosure* scan_non_heap_roots, 833 OopsInHeapRegionClosure* scan_rs, 834 G1KlassScanClosure* scan_klasses, 835 uint worker_i); 836 837 // Notifies all the necessary spaces that the committed space has 838 // been updated (either expanded or shrunk). It should be called 839 // after _g1_storage is updated. 840 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 841 842 // The concurrent marker (and the thread it runs in.) 843 ConcurrentMark* _cm; 844 ConcurrentMarkThread* _cmThread; 845 bool _mark_in_progress; 846 847 // The concurrent refiner. 848 ConcurrentG1Refine* _cg1r; 849 850 // The parallel task queues 851 RefToScanQueueSet *_task_queues; 852 853 // True iff a evacuation has failed in the current collection. 854 bool _evacuation_failed; 855 856 EvacuationFailedInfo* _evacuation_failed_info_array; 857 858 // Failed evacuations cause some logical from-space objects to have 859 // forwarding pointers to themselves. Reset them. 860 void remove_self_forwarding_pointers(); 861 862 // Together, these store an object with a preserved mark, and its mark value. 863 Stack<oop, mtGC> _objs_with_preserved_marks; 864 Stack<markOop, mtGC> _preserved_marks_of_objs; 865 866 // Preserve the mark of "obj", if necessary, in preparation for its mark 867 // word being overwritten with a self-forwarding-pointer. 868 void preserve_mark_if_necessary(oop obj, markOop m); 869 870 // The stack of evac-failure objects left to be scanned. 871 GrowableArray<oop>* _evac_failure_scan_stack; 872 // The closure to apply to evac-failure objects. 873 874 OopsInHeapRegionClosure* _evac_failure_closure; 875 // Set the field above. 876 void 877 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 878 _evac_failure_closure = evac_failure_closure; 879 } 880 881 // Push "obj" on the scan stack. 882 void push_on_evac_failure_scan_stack(oop obj); 883 // Process scan stack entries until the stack is empty. 884 void drain_evac_failure_scan_stack(); 885 // True iff an invocation of "drain_scan_stack" is in progress; to 886 // prevent unnecessary recursion. 887 bool _drain_in_progress; 888 889 // Do any necessary initialization for evacuation-failure handling. 890 // "cl" is the closure that will be used to process evac-failure 891 // objects. 892 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 893 // Do any necessary cleanup for evacuation-failure handling data 894 // structures. 895 void finalize_for_evac_failure(); 896 897 // An attempt to evacuate "obj" has failed; take necessary steps. 898 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 899 void handle_evacuation_failure_common(oop obj, markOop m); 900 901 #ifndef PRODUCT 902 // Support for forcing evacuation failures. Analogous to 903 // PromotionFailureALot for the other collectors. 904 905 // Records whether G1EvacuationFailureALot should be in effect 906 // for the current GC 907 bool _evacuation_failure_alot_for_current_gc; 908 909 // Used to record the GC number for interval checking when 910 // determining whether G1EvaucationFailureALot is in effect 911 // for the current GC. 912 size_t _evacuation_failure_alot_gc_number; 913 914 // Count of the number of evacuations between failures. 915 volatile size_t _evacuation_failure_alot_count; 916 917 // Set whether G1EvacuationFailureALot should be in effect 918 // for the current GC (based upon the type of GC and which 919 // command line flags are set); 920 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 921 bool during_initial_mark, 922 bool during_marking); 923 924 inline void set_evacuation_failure_alot_for_current_gc(); 925 926 // Return true if it's time to cause an evacuation failure. 927 inline bool evacuation_should_fail(); 928 929 // Reset the G1EvacuationFailureALot counters. Should be called at 930 // the end of an evacuation pause in which an evacuation failure occurred. 931 inline void reset_evacuation_should_fail(); 932 #endif // !PRODUCT 933 934 // ("Weak") Reference processing support. 935 // 936 // G1 has 2 instances of the reference processor class. One 937 // (_ref_processor_cm) handles reference object discovery 938 // and subsequent processing during concurrent marking cycles. 939 // 940 // The other (_ref_processor_stw) handles reference object 941 // discovery and processing during full GCs and incremental 942 // evacuation pauses. 943 // 944 // During an incremental pause, reference discovery will be 945 // temporarily disabled for _ref_processor_cm and will be 946 // enabled for _ref_processor_stw. At the end of the evacuation 947 // pause references discovered by _ref_processor_stw will be 948 // processed and discovery will be disabled. The previous 949 // setting for reference object discovery for _ref_processor_cm 950 // will be re-instated. 951 // 952 // At the start of marking: 953 // * Discovery by the CM ref processor is verified to be inactive 954 // and it's discovered lists are empty. 955 // * Discovery by the CM ref processor is then enabled. 956 // 957 // At the end of marking: 958 // * Any references on the CM ref processor's discovered 959 // lists are processed (possibly MT). 960 // 961 // At the start of full GC we: 962 // * Disable discovery by the CM ref processor and 963 // empty CM ref processor's discovered lists 964 // (without processing any entries). 965 // * Verify that the STW ref processor is inactive and it's 966 // discovered lists are empty. 967 // * Temporarily set STW ref processor discovery as single threaded. 968 // * Temporarily clear the STW ref processor's _is_alive_non_header 969 // field. 970 // * Finally enable discovery by the STW ref processor. 971 // 972 // The STW ref processor is used to record any discovered 973 // references during the full GC. 974 // 975 // At the end of a full GC we: 976 // * Enqueue any reference objects discovered by the STW ref processor 977 // that have non-live referents. This has the side-effect of 978 // making the STW ref processor inactive by disabling discovery. 979 // * Verify that the CM ref processor is still inactive 980 // and no references have been placed on it's discovered 981 // lists (also checked as a precondition during initial marking). 982 983 // The (stw) reference processor... 984 ReferenceProcessor* _ref_processor_stw; 985 986 STWGCTimer* _gc_timer_stw; 987 ConcurrentGCTimer* _gc_timer_cm; 988 989 G1OldTracer* _gc_tracer_cm; 990 G1NewTracer* _gc_tracer_stw; 991 992 // During reference object discovery, the _is_alive_non_header 993 // closure (if non-null) is applied to the referent object to 994 // determine whether the referent is live. If so then the 995 // reference object does not need to be 'discovered' and can 996 // be treated as a regular oop. This has the benefit of reducing 997 // the number of 'discovered' reference objects that need to 998 // be processed. 999 // 1000 // Instance of the is_alive closure for embedding into the 1001 // STW reference processor as the _is_alive_non_header field. 1002 // Supplying a value for the _is_alive_non_header field is 1003 // optional but doing so prevents unnecessary additions to 1004 // the discovered lists during reference discovery. 1005 G1STWIsAliveClosure _is_alive_closure_stw; 1006 1007 // The (concurrent marking) reference processor... 1008 ReferenceProcessor* _ref_processor_cm; 1009 1010 // Instance of the concurrent mark is_alive closure for embedding 1011 // into the Concurrent Marking reference processor as the 1012 // _is_alive_non_header field. Supplying a value for the 1013 // _is_alive_non_header field is optional but doing so prevents 1014 // unnecessary additions to the discovered lists during reference 1015 // discovery. 1016 G1CMIsAliveClosure _is_alive_closure_cm; 1017 1018 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1019 HeapRegion** _worker_cset_start_region; 1020 1021 // Time stamp to validate the regions recorded in the cache 1022 // used by G1CollectedHeap::start_cset_region_for_worker(). 1023 // The heap region entry for a given worker is valid iff 1024 // the associated time stamp value matches the current value 1025 // of G1CollectedHeap::_gc_time_stamp. 1026 unsigned int* _worker_cset_start_region_time_stamp; 1027 1028 enum G1H_process_strong_roots_tasks { 1029 G1H_PS_filter_satb_buffers, 1030 G1H_PS_refProcessor_oops_do, 1031 // Leave this one last. 1032 G1H_PS_NumElements 1033 }; 1034 1035 SubTasksDone* _process_strong_tasks; 1036 1037 volatile bool _free_regions_coming; 1038 1039 public: 1040 1041 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1042 1043 void set_refine_cte_cl_concurrency(bool concurrent); 1044 1045 RefToScanQueue *task_queue(int i) const; 1046 1047 // A set of cards where updates happened during the GC 1048 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1049 1050 // A DirtyCardQueueSet that is used to hold cards that contain 1051 // references into the current collection set. This is used to 1052 // update the remembered sets of the regions in the collection 1053 // set in the event of an evacuation failure. 1054 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1055 { return _into_cset_dirty_card_queue_set; } 1056 1057 // Create a G1CollectedHeap with the specified policy. 1058 // Must call the initialize method afterwards. 1059 // May not return if something goes wrong. 1060 G1CollectedHeap(G1CollectorPolicy* policy); 1061 1062 // Initialize the G1CollectedHeap to have the initial and 1063 // maximum sizes and remembered and barrier sets 1064 // specified by the policy object. 1065 jint initialize(); 1066 1067 virtual void stop(); 1068 1069 // Return the (conservative) maximum heap alignment for any G1 heap 1070 static size_t conservative_max_heap_alignment(); 1071 1072 // Initialize weak reference processing. 1073 virtual void ref_processing_init(); 1074 1075 void set_par_threads(uint t) { 1076 SharedHeap::set_par_threads(t); 1077 // Done in SharedHeap but oddly there are 1078 // two _process_strong_tasks's in a G1CollectedHeap 1079 // so do it here too. 1080 _process_strong_tasks->set_n_threads(t); 1081 } 1082 1083 // Set _n_par_threads according to a policy TBD. 1084 void set_par_threads(); 1085 1086 void set_n_termination(int t) { 1087 _process_strong_tasks->set_n_threads(t); 1088 } 1089 1090 virtual CollectedHeap::Name kind() const { 1091 return CollectedHeap::G1CollectedHeap; 1092 } 1093 1094 // The current policy object for the collector. 1095 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1096 1097 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1098 1099 // Adaptive size policy. No such thing for g1. 1100 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1101 1102 // The rem set and barrier set. 1103 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1104 1105 unsigned get_gc_time_stamp() { 1106 return _gc_time_stamp; 1107 } 1108 1109 inline void reset_gc_time_stamp(); 1110 1111 void check_gc_time_stamps() PRODUCT_RETURN; 1112 1113 inline void increment_gc_time_stamp(); 1114 1115 // Reset the given region's GC timestamp. If it's starts humongous, 1116 // also reset the GC timestamp of its corresponding 1117 // continues humongous regions too. 1118 void reset_gc_time_stamps(HeapRegion* hr); 1119 1120 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1121 DirtyCardQueue* into_cset_dcq, 1122 bool concurrent, uint worker_i); 1123 1124 // The shared block offset table array. 1125 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1126 1127 // Reference Processing accessors 1128 1129 // The STW reference processor.... 1130 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1131 1132 // The Concurrent Marking reference processor... 1133 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1134 1135 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1136 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1137 1138 virtual size_t capacity() const; 1139 virtual size_t used() const; 1140 // This should be called when we're not holding the heap lock. The 1141 // result might be a bit inaccurate. 1142 size_t used_unlocked() const; 1143 size_t recalculate_used() const; 1144 1145 // These virtual functions do the actual allocation. 1146 // Some heaps may offer a contiguous region for shared non-blocking 1147 // allocation, via inlined code (by exporting the address of the top and 1148 // end fields defining the extent of the contiguous allocation region.) 1149 // But G1CollectedHeap doesn't yet support this. 1150 1151 virtual bool is_maximal_no_gc() const { 1152 return _g1_storage.uncommitted_size() == 0; 1153 } 1154 1155 // The total number of regions in the heap. 1156 uint n_regions() const { return _hrs.length(); } 1157 1158 // The max number of regions in the heap. 1159 uint max_regions() { return _hrs.max_length(); } 1160 1161 // The number of regions that are completely free. 1162 uint free_regions() { return _free_list.length(); } 1163 1164 // The number of regions that are not completely free. 1165 uint used_regions() { return n_regions() - free_regions(); } 1166 1167 // The number of regions available for "regular" expansion. 1168 uint expansion_regions() { return _expansion_regions; } 1169 1170 // Factory method for HeapRegion instances. It will return NULL if 1171 // the allocation fails. 1172 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1173 1174 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1175 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1176 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1177 void verify_dirty_young_regions() PRODUCT_RETURN; 1178 1179 #ifndef PRODUCT 1180 // Make sure that the given bitmap has no marked objects in the 1181 // range [from,limit). If it does, print an error message and return 1182 // false. Otherwise, just return true. bitmap_name should be "prev" 1183 // or "next". 1184 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1185 HeapWord* from, HeapWord* limit); 1186 1187 // Verify that the prev / next bitmap range [tams,end) for the given 1188 // region has no marks. Return true if all is well, false if errors 1189 // are detected. 1190 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1191 #endif // PRODUCT 1192 1193 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1194 // the given region do not have any spurious marks. If errors are 1195 // detected, print appropriate error messages and crash. 1196 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1197 1198 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1199 // have any spurious marks. If errors are detected, print 1200 // appropriate error messages and crash. 1201 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1202 1203 // verify_region_sets() performs verification over the region 1204 // lists. It will be compiled in the product code to be used when 1205 // necessary (i.e., during heap verification). 1206 void verify_region_sets(); 1207 1208 // verify_region_sets_optional() is planted in the code for 1209 // list verification in non-product builds (and it can be enabled in 1210 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1211 #if HEAP_REGION_SET_FORCE_VERIFY 1212 void verify_region_sets_optional() { 1213 verify_region_sets(); 1214 } 1215 #else // HEAP_REGION_SET_FORCE_VERIFY 1216 void verify_region_sets_optional() { } 1217 #endif // HEAP_REGION_SET_FORCE_VERIFY 1218 1219 #ifdef ASSERT 1220 bool is_on_master_free_list(HeapRegion* hr) { 1221 return hr->containing_set() == &_free_list; 1222 } 1223 #endif // ASSERT 1224 1225 // Wrapper for the region list operations that can be called from 1226 // methods outside this class. 1227 1228 void secondary_free_list_add(FreeRegionList* list) { 1229 _secondary_free_list.add_ordered(list); 1230 } 1231 1232 void append_secondary_free_list() { 1233 _free_list.add_ordered(&_secondary_free_list); 1234 } 1235 1236 void append_secondary_free_list_if_not_empty_with_lock() { 1237 // If the secondary free list looks empty there's no reason to 1238 // take the lock and then try to append it. 1239 if (!_secondary_free_list.is_empty()) { 1240 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1241 append_secondary_free_list(); 1242 } 1243 } 1244 1245 inline void old_set_remove(HeapRegion* hr); 1246 1247 size_t non_young_capacity_bytes() { 1248 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1249 } 1250 1251 void set_free_regions_coming(); 1252 void reset_free_regions_coming(); 1253 bool free_regions_coming() { return _free_regions_coming; } 1254 void wait_while_free_regions_coming(); 1255 1256 // Determine whether the given region is one that we are using as an 1257 // old GC alloc region. 1258 bool is_old_gc_alloc_region(HeapRegion* hr) { 1259 return hr == _retained_old_gc_alloc_region; 1260 } 1261 1262 // Perform a collection of the heap; intended for use in implementing 1263 // "System.gc". This probably implies as full a collection as the 1264 // "CollectedHeap" supports. 1265 virtual void collect(GCCause::Cause cause); 1266 1267 // The same as above but assume that the caller holds the Heap_lock. 1268 void collect_locked(GCCause::Cause cause); 1269 1270 // True iff an evacuation has failed in the most-recent collection. 1271 bool evacuation_failed() { return _evacuation_failed; } 1272 1273 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1274 void prepend_to_freelist(FreeRegionList* list); 1275 void decrement_summary_bytes(size_t bytes); 1276 1277 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1278 virtual bool is_in(const void* p) const; 1279 1280 // Return "TRUE" iff the given object address is within the collection 1281 // set. 1282 inline bool obj_in_cs(oop obj); 1283 1284 // Return "TRUE" iff the given object address is in the reserved 1285 // region of g1. 1286 bool is_in_g1_reserved(const void* p) const { 1287 return _g1_reserved.contains(p); 1288 } 1289 1290 // Returns a MemRegion that corresponds to the space that has been 1291 // reserved for the heap 1292 MemRegion g1_reserved() { 1293 return _g1_reserved; 1294 } 1295 1296 // Returns a MemRegion that corresponds to the space that has been 1297 // committed in the heap 1298 MemRegion g1_committed() { 1299 return _g1_committed; 1300 } 1301 1302 virtual bool is_in_closed_subset(const void* p) const; 1303 1304 G1SATBCardTableModRefBS* g1_barrier_set() { 1305 return (G1SATBCardTableModRefBS*) barrier_set(); 1306 } 1307 1308 // This resets the card table to all zeros. It is used after 1309 // a collection pause which used the card table to claim cards. 1310 void cleanUpCardTable(); 1311 1312 // Iteration functions. 1313 1314 // Iterate over all the ref-containing fields of all objects, calling 1315 // "cl.do_oop" on each. 1316 virtual void oop_iterate(ExtendedOopClosure* cl); 1317 1318 // Same as above, restricted to a memory region. 1319 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1320 1321 // Iterate over all objects, calling "cl.do_object" on each. 1322 virtual void object_iterate(ObjectClosure* cl); 1323 1324 virtual void safe_object_iterate(ObjectClosure* cl) { 1325 object_iterate(cl); 1326 } 1327 1328 // Iterate over all spaces in use in the heap, in ascending address order. 1329 virtual void space_iterate(SpaceClosure* cl); 1330 1331 // Iterate over heap regions, in address order, terminating the 1332 // iteration early if the "doHeapRegion" method returns "true". 1333 void heap_region_iterate(HeapRegionClosure* blk) const; 1334 1335 // Return the region with the given index. It assumes the index is valid. 1336 inline HeapRegion* region_at(uint index) const; 1337 1338 // Divide the heap region sequence into "chunks" of some size (the number 1339 // of regions divided by the number of parallel threads times some 1340 // overpartition factor, currently 4). Assumes that this will be called 1341 // in parallel by ParallelGCThreads worker threads with distinct worker 1342 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1343 // calls will use the same "claim_value", and that that claim value is 1344 // different from the claim_value of any heap region before the start of 1345 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1346 // attempting to claim the first region in each chunk, and, if 1347 // successful, applying the closure to each region in the chunk (and 1348 // setting the claim value of the second and subsequent regions of the 1349 // chunk.) For now requires that "doHeapRegion" always returns "false", 1350 // i.e., that a closure never attempt to abort a traversal. 1351 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1352 uint worker, 1353 uint no_of_par_workers, 1354 jint claim_value); 1355 1356 // It resets all the region claim values to the default. 1357 void reset_heap_region_claim_values(); 1358 1359 // Resets the claim values of regions in the current 1360 // collection set to the default. 1361 void reset_cset_heap_region_claim_values(); 1362 1363 #ifdef ASSERT 1364 bool check_heap_region_claim_values(jint claim_value); 1365 1366 // Same as the routine above but only checks regions in the 1367 // current collection set. 1368 bool check_cset_heap_region_claim_values(jint claim_value); 1369 #endif // ASSERT 1370 1371 // Clear the cached cset start regions and (more importantly) 1372 // the time stamps. Called when we reset the GC time stamp. 1373 void clear_cset_start_regions(); 1374 1375 // Given the id of a worker, obtain or calculate a suitable 1376 // starting region for iterating over the current collection set. 1377 HeapRegion* start_cset_region_for_worker(uint worker_i); 1378 1379 // This is a convenience method that is used by the 1380 // HeapRegionIterator classes to calculate the starting region for 1381 // each worker so that they do not all start from the same region. 1382 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1383 1384 // Iterate over the regions (if any) in the current collection set. 1385 void collection_set_iterate(HeapRegionClosure* blk); 1386 1387 // As above but starting from region r 1388 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1389 1390 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1391 1392 // A CollectedHeap will contain some number of spaces. This finds the 1393 // space containing a given address, or else returns NULL. 1394 virtual Space* space_containing(const void* addr) const; 1395 1396 // Returns the HeapRegion that contains addr. addr must not be NULL. 1397 template <class T> 1398 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1399 1400 // Returns the HeapRegion that contains addr. addr must not be NULL. 1401 // If addr is within a humongous continues region, it returns its humongous start region. 1402 template <class T> 1403 inline HeapRegion* heap_region_containing(const T addr) const; 1404 1405 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1406 // each address in the (reserved) heap is a member of exactly 1407 // one block. The defining characteristic of a block is that it is 1408 // possible to find its size, and thus to progress forward to the next 1409 // block. (Blocks may be of different sizes.) Thus, blocks may 1410 // represent Java objects, or they might be free blocks in a 1411 // free-list-based heap (or subheap), as long as the two kinds are 1412 // distinguishable and the size of each is determinable. 1413 1414 // Returns the address of the start of the "block" that contains the 1415 // address "addr". We say "blocks" instead of "object" since some heaps 1416 // may not pack objects densely; a chunk may either be an object or a 1417 // non-object. 1418 virtual HeapWord* block_start(const void* addr) const; 1419 1420 // Requires "addr" to be the start of a chunk, and returns its size. 1421 // "addr + size" is required to be the start of a new chunk, or the end 1422 // of the active area of the heap. 1423 virtual size_t block_size(const HeapWord* addr) const; 1424 1425 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1426 // the block is an object. 1427 virtual bool block_is_obj(const HeapWord* addr) const; 1428 1429 // Does this heap support heap inspection? (+PrintClassHistogram) 1430 virtual bool supports_heap_inspection() const { return true; } 1431 1432 // Section on thread-local allocation buffers (TLABs) 1433 // See CollectedHeap for semantics. 1434 1435 bool supports_tlab_allocation() const; 1436 size_t tlab_capacity(Thread* ignored) const; 1437 size_t tlab_used(Thread* ignored) const; 1438 size_t max_tlab_size() const; 1439 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1440 1441 // Can a compiler initialize a new object without store barriers? 1442 // This permission only extends from the creation of a new object 1443 // via a TLAB up to the first subsequent safepoint. If such permission 1444 // is granted for this heap type, the compiler promises to call 1445 // defer_store_barrier() below on any slow path allocation of 1446 // a new object for which such initializing store barriers will 1447 // have been elided. G1, like CMS, allows this, but should be 1448 // ready to provide a compensating write barrier as necessary 1449 // if that storage came out of a non-young region. The efficiency 1450 // of this implementation depends crucially on being able to 1451 // answer very efficiently in constant time whether a piece of 1452 // storage in the heap comes from a young region or not. 1453 // See ReduceInitialCardMarks. 1454 virtual bool can_elide_tlab_store_barriers() const { 1455 return true; 1456 } 1457 1458 virtual bool card_mark_must_follow_store() const { 1459 return true; 1460 } 1461 1462 inline bool is_in_young(const oop obj); 1463 1464 #ifdef ASSERT 1465 virtual bool is_in_partial_collection(const void* p); 1466 #endif 1467 1468 virtual bool is_scavengable(const void* addr); 1469 1470 // We don't need barriers for initializing stores to objects 1471 // in the young gen: for the SATB pre-barrier, there is no 1472 // pre-value that needs to be remembered; for the remembered-set 1473 // update logging post-barrier, we don't maintain remembered set 1474 // information for young gen objects. 1475 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1476 1477 // Returns "true" iff the given word_size is "very large". 1478 static bool isHumongous(size_t word_size) { 1479 // Note this has to be strictly greater-than as the TLABs 1480 // are capped at the humongous threshold and we want to 1481 // ensure that we don't try to allocate a TLAB as 1482 // humongous and that we don't allocate a humongous 1483 // object in a TLAB. 1484 return word_size > _humongous_object_threshold_in_words; 1485 } 1486 1487 // Update mod union table with the set of dirty cards. 1488 void updateModUnion(); 1489 1490 // Set the mod union bits corresponding to the given memRegion. Note 1491 // that this is always a safe operation, since it doesn't clear any 1492 // bits. 1493 void markModUnionRange(MemRegion mr); 1494 1495 // Records the fact that a marking phase is no longer in progress. 1496 void set_marking_complete() { 1497 _mark_in_progress = false; 1498 } 1499 void set_marking_started() { 1500 _mark_in_progress = true; 1501 } 1502 bool mark_in_progress() { 1503 return _mark_in_progress; 1504 } 1505 1506 // Print the maximum heap capacity. 1507 virtual size_t max_capacity() const; 1508 1509 virtual jlong millis_since_last_gc(); 1510 1511 1512 // Convenience function to be used in situations where the heap type can be 1513 // asserted to be this type. 1514 static G1CollectedHeap* heap(); 1515 1516 void set_region_short_lived_locked(HeapRegion* hr); 1517 // add appropriate methods for any other surv rate groups 1518 1519 YoungList* young_list() const { return _young_list; } 1520 1521 // debugging 1522 bool check_young_list_well_formed() { 1523 return _young_list->check_list_well_formed(); 1524 } 1525 1526 bool check_young_list_empty(bool check_heap, 1527 bool check_sample = true); 1528 1529 // *** Stuff related to concurrent marking. It's not clear to me that so 1530 // many of these need to be public. 1531 1532 // The functions below are helper functions that a subclass of 1533 // "CollectedHeap" can use in the implementation of its virtual 1534 // functions. 1535 // This performs a concurrent marking of the live objects in a 1536 // bitmap off to the side. 1537 void doConcurrentMark(); 1538 1539 bool isMarkedPrev(oop obj) const; 1540 bool isMarkedNext(oop obj) const; 1541 1542 // Determine if an object is dead, given the object and also 1543 // the region to which the object belongs. An object is dead 1544 // iff a) it was not allocated since the last mark and b) it 1545 // is not marked. 1546 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1547 return 1548 !hr->obj_allocated_since_prev_marking(obj) && 1549 !isMarkedPrev(obj); 1550 } 1551 1552 // This function returns true when an object has been 1553 // around since the previous marking and hasn't yet 1554 // been marked during this marking. 1555 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1556 return 1557 !hr->obj_allocated_since_next_marking(obj) && 1558 !isMarkedNext(obj); 1559 } 1560 1561 // Determine if an object is dead, given only the object itself. 1562 // This will find the region to which the object belongs and 1563 // then call the region version of the same function. 1564 1565 // Added if it is NULL it isn't dead. 1566 1567 inline bool is_obj_dead(const oop obj) const; 1568 1569 inline bool is_obj_ill(const oop obj) const; 1570 1571 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1572 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1573 bool is_marked(oop obj, VerifyOption vo); 1574 const char* top_at_mark_start_str(VerifyOption vo); 1575 1576 ConcurrentMark* concurrent_mark() const { return _cm; } 1577 1578 // Refinement 1579 1580 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1581 1582 // The dirty cards region list is used to record a subset of regions 1583 // whose cards need clearing. The list if populated during the 1584 // remembered set scanning and drained during the card table 1585 // cleanup. Although the methods are reentrant, population/draining 1586 // phases must not overlap. For synchronization purposes the last 1587 // element on the list points to itself. 1588 HeapRegion* _dirty_cards_region_list; 1589 void push_dirty_cards_region(HeapRegion* hr); 1590 HeapRegion* pop_dirty_cards_region(); 1591 1592 // Optimized nmethod scanning support routines 1593 1594 // Register the given nmethod with the G1 heap. 1595 virtual void register_nmethod(nmethod* nm); 1596 1597 // Unregister the given nmethod from the G1 heap. 1598 virtual void unregister_nmethod(nmethod* nm); 1599 1600 // Migrate the nmethods in the code root lists of the regions 1601 // in the collection set to regions in to-space. In the event 1602 // of an evacuation failure, nmethods that reference objects 1603 // that were not successfully evacuated are not migrated. 1604 void migrate_strong_code_roots(); 1605 1606 // Free up superfluous code root memory. 1607 void purge_code_root_memory(); 1608 1609 // During an initial mark pause, mark all the code roots that 1610 // point into regions *not* in the collection set. 1611 void mark_strong_code_roots(uint worker_id); 1612 1613 // Rebuild the strong code root lists for each region 1614 // after a full GC. 1615 void rebuild_strong_code_roots(); 1616 1617 // Delete entries for dead interned string and clean up unreferenced symbols 1618 // in symbol table, possibly in parallel. 1619 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1620 1621 // Redirty logged cards in the refinement queue. 1622 void redirty_logged_cards(); 1623 // Verification 1624 1625 // The following is just to alert the verification code 1626 // that a full collection has occurred and that the 1627 // remembered sets are no longer up to date. 1628 bool _full_collection; 1629 void set_full_collection() { _full_collection = true;} 1630 void clear_full_collection() {_full_collection = false;} 1631 bool full_collection() {return _full_collection;} 1632 1633 // Perform any cleanup actions necessary before allowing a verification. 1634 virtual void prepare_for_verify(); 1635 1636 // Perform verification. 1637 1638 // vo == UsePrevMarking -> use "prev" marking information, 1639 // vo == UseNextMarking -> use "next" marking information 1640 // vo == UseMarkWord -> use the mark word in the object header 1641 // 1642 // NOTE: Only the "prev" marking information is guaranteed to be 1643 // consistent most of the time, so most calls to this should use 1644 // vo == UsePrevMarking. 1645 // Currently, there is only one case where this is called with 1646 // vo == UseNextMarking, which is to verify the "next" marking 1647 // information at the end of remark. 1648 // Currently there is only one place where this is called with 1649 // vo == UseMarkWord, which is to verify the marking during a 1650 // full GC. 1651 void verify(bool silent, VerifyOption vo); 1652 1653 // Override; it uses the "prev" marking information 1654 virtual void verify(bool silent); 1655 1656 // The methods below are here for convenience and dispatch the 1657 // appropriate method depending on value of the given VerifyOption 1658 // parameter. The values for that parameter, and their meanings, 1659 // are the same as those above. 1660 1661 bool is_obj_dead_cond(const oop obj, 1662 const HeapRegion* hr, 1663 const VerifyOption vo) const; 1664 1665 bool is_obj_dead_cond(const oop obj, 1666 const VerifyOption vo) const; 1667 1668 // Printing 1669 1670 virtual void print_on(outputStream* st) const; 1671 virtual void print_extended_on(outputStream* st) const; 1672 virtual void print_on_error(outputStream* st) const; 1673 1674 virtual void print_gc_threads_on(outputStream* st) const; 1675 virtual void gc_threads_do(ThreadClosure* tc) const; 1676 1677 // Override 1678 void print_tracing_info() const; 1679 1680 // The following two methods are helpful for debugging RSet issues. 1681 void print_cset_rsets() PRODUCT_RETURN; 1682 void print_all_rsets() PRODUCT_RETURN; 1683 1684 public: 1685 size_t pending_card_num(); 1686 size_t cards_scanned(); 1687 1688 protected: 1689 size_t _max_heap_capacity; 1690 }; 1691 1692 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1693 private: 1694 bool _retired; 1695 1696 public: 1697 G1ParGCAllocBuffer(size_t gclab_word_size); 1698 virtual ~G1ParGCAllocBuffer() { 1699 guarantee(_retired, "Allocation buffer has not been retired"); 1700 } 1701 1702 virtual void set_buf(HeapWord* buf) { 1703 ParGCAllocBuffer::set_buf(buf); 1704 _retired = false; 1705 } 1706 1707 virtual void retire(bool end_of_gc, bool retain) { 1708 if (_retired) { 1709 return; 1710 } 1711 ParGCAllocBuffer::retire(end_of_gc, retain); 1712 _retired = true; 1713 } 1714 }; 1715 1716 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP