1 /* 2 * Copyright (c) 2001, 2015, 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_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/concurrentMark.hpp" 29 #include "gc/g1/evacuationInfo.hpp" 30 #include "gc/g1/g1AllocRegion.hpp" 31 #include "gc/g1/g1AllocationContext.hpp" 32 #include "gc/g1/g1Allocator.hpp" 33 #include "gc/g1/g1BiasedArray.hpp" 34 #include "gc/g1/g1CollectorState.hpp" 35 #include "gc/g1/g1HRPrinter.hpp" 36 #include "gc/g1/g1InCSetState.hpp" 37 #include "gc/g1/g1MonitoringSupport.hpp" 38 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 39 #include "gc/g1/g1YCTypes.hpp" 40 #include "gc/g1/hSpaceCounters.hpp" 41 #include "gc/g1/heapRegionManager.hpp" 42 #include "gc/g1/heapRegionSet.hpp" 43 #include "gc/shared/barrierSet.hpp" 44 #include "gc/shared/collectedHeap.hpp" 45 #include "memory/memRegion.hpp" 46 #include "utilities/stack.hpp" 47 48 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 49 // It uses the "Garbage First" heap organization and algorithm, which 50 // may combine concurrent marking with parallel, incremental compaction of 51 // heap subsets that will yield large amounts of garbage. 52 53 // Forward declarations 54 class HeapRegion; 55 class HRRSCleanupTask; 56 class GenerationSpec; 57 class OopsInHeapRegionClosure; 58 class G1KlassScanClosure; 59 class G1ParScanThreadState; 60 class ObjectClosure; 61 class SpaceClosure; 62 class CompactibleSpaceClosure; 63 class Space; 64 class G1CollectorPolicy; 65 class GenRemSet; 66 class G1RemSet; 67 class HeapRegionRemSetIterator; 68 class ConcurrentMark; 69 class ConcurrentMarkThread; 70 class ConcurrentG1Refine; 71 class ConcurrentGCTimer; 72 class GenerationCounters; 73 class STWGCTimer; 74 class G1NewTracer; 75 class G1OldTracer; 76 class EvacuationFailedInfo; 77 class nmethod; 78 class Ticks; 79 class FlexibleWorkGang; 80 81 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 82 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 83 84 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 85 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 86 87 class YoungList : public CHeapObj<mtGC> { 88 private: 89 G1CollectedHeap* _g1h; 90 91 HeapRegion* _head; 92 93 HeapRegion* _survivor_head; 94 HeapRegion* _survivor_tail; 95 96 HeapRegion* _curr; 97 98 uint _length; 99 uint _survivor_length; 100 101 size_t _last_sampled_rs_lengths; 102 size_t _sampled_rs_lengths; 103 104 void empty_list(HeapRegion* list); 105 106 public: 107 YoungList(G1CollectedHeap* g1h); 108 109 void push_region(HeapRegion* hr); 110 void add_survivor_region(HeapRegion* hr); 111 112 void empty_list(); 113 bool is_empty() { return _length == 0; } 114 uint length() { return _length; } 115 uint eden_length() { return length() - survivor_length(); } 116 uint survivor_length() { return _survivor_length; } 117 118 // Currently we do not keep track of the used byte sum for the 119 // young list and the survivors and it'd be quite a lot of work to 120 // do so. When we'll eventually replace the young list with 121 // instances of HeapRegionLinkedList we'll get that for free. So, 122 // we'll report the more accurate information then. 123 size_t eden_used_bytes() { 124 assert(length() >= survivor_length(), "invariant"); 125 return (size_t) eden_length() * HeapRegion::GrainBytes; 126 } 127 size_t survivor_used_bytes() { 128 return (size_t) survivor_length() * HeapRegion::GrainBytes; 129 } 130 131 void rs_length_sampling_init(); 132 bool rs_length_sampling_more(); 133 void rs_length_sampling_next(); 134 135 void reset_sampled_info() { 136 _last_sampled_rs_lengths = 0; 137 } 138 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 139 140 // for development purposes 141 void reset_auxilary_lists(); 142 void clear() { _head = NULL; _length = 0; } 143 144 void clear_survivors() { 145 _survivor_head = NULL; 146 _survivor_tail = NULL; 147 _survivor_length = 0; 148 } 149 150 HeapRegion* first_region() { return _head; } 151 HeapRegion* first_survivor_region() { return _survivor_head; } 152 HeapRegion* last_survivor_region() { return _survivor_tail; } 153 154 // debugging 155 bool check_list_well_formed(); 156 bool check_list_empty(bool check_sample = true); 157 void print(); 158 }; 159 160 // The G1 STW is alive closure. 161 // An instance is embedded into the G1CH and used as the 162 // (optional) _is_alive_non_header closure in the STW 163 // reference processor. It is also extensively used during 164 // reference processing during STW evacuation pauses. 165 class G1STWIsAliveClosure: public BoolObjectClosure { 166 G1CollectedHeap* _g1; 167 public: 168 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 169 bool do_object_b(oop p); 170 }; 171 172 class RefineCardTableEntryClosure; 173 174 class G1RegionMappingChangedListener : public G1MappingChangedListener { 175 private: 176 void reset_from_card_cache(uint start_idx, size_t num_regions); 177 public: 178 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 179 }; 180 181 class G1CollectedHeap : public CollectedHeap { 182 friend class VM_CollectForMetadataAllocation; 183 friend class VM_G1CollectForAllocation; 184 friend class VM_G1CollectFull; 185 friend class VM_G1IncCollectionPause; 186 friend class VMStructs; 187 friend class MutatorAllocRegion; 188 friend class SurvivorGCAllocRegion; 189 friend class OldGCAllocRegion; 190 friend class G1Allocator; 191 friend class G1ArchiveAllocator; 192 193 // Closures used in implementation. 194 friend class G1ParScanThreadState; 195 friend class G1ParTask; 196 friend class G1ParGCAllocator; 197 friend class G1PrepareCompactClosure; 198 199 // Other related classes. 200 friend class HeapRegionClaimer; 201 202 // Testing classes. 203 friend class G1CheckCSetFastTableClosure; 204 205 private: 206 FlexibleWorkGang* _workers; 207 208 static size_t _humongous_object_threshold_in_words; 209 210 // The secondary free list which contains regions that have been 211 // freed up during the cleanup process. This will be appended to 212 // the master free list when appropriate. 213 FreeRegionList _secondary_free_list; 214 215 // It keeps track of the old regions. 216 HeapRegionSet _old_set; 217 218 // It keeps track of the humongous regions. 219 HeapRegionSet _humongous_set; 220 221 void eagerly_reclaim_humongous_regions(); 222 223 // The number of regions we could create by expansion. 224 uint _expansion_regions; 225 226 // The block offset table for the G1 heap. 227 G1BlockOffsetSharedArray* _bot_shared; 228 229 // Tears down the region sets / lists so that they are empty and the 230 // regions on the heap do not belong to a region set / list. The 231 // only exception is the humongous set which we leave unaltered. If 232 // free_list_only is true, it will only tear down the master free 233 // list. It is called before a Full GC (free_list_only == false) or 234 // before heap shrinking (free_list_only == true). 235 void tear_down_region_sets(bool free_list_only); 236 237 // Rebuilds the region sets / lists so that they are repopulated to 238 // reflect the contents of the heap. The only exception is the 239 // humongous set which was not torn down in the first place. If 240 // free_list_only is true, it will only rebuild the master free 241 // list. It is called after a Full GC (free_list_only == false) or 242 // after heap shrinking (free_list_only == true). 243 void rebuild_region_sets(bool free_list_only); 244 245 // Callback for region mapping changed events. 246 G1RegionMappingChangedListener _listener; 247 248 // The sequence of all heap regions in the heap. 249 HeapRegionManager _hrm; 250 251 // Class that handles the different kinds of allocations. 252 G1Allocator* _allocator; 253 254 // Class that handles archive allocation ranges. 255 G1ArchiveAllocator* _archive_allocator; 256 257 // Statistics for each allocation context 258 AllocationContextStats _allocation_context_stats; 259 260 // PLAB sizing policy for survivors. 261 PLABStats _survivor_plab_stats; 262 263 // PLAB sizing policy for tenured objects. 264 PLABStats _old_plab_stats; 265 266 // It specifies whether we should attempt to expand the heap after a 267 // region allocation failure. If heap expansion fails we set this to 268 // false so that we don't re-attempt the heap expansion (it's likely 269 // that subsequent expansion attempts will also fail if one fails). 270 // Currently, it is only consulted during GC and it's reset at the 271 // start of each GC. 272 bool _expand_heap_after_alloc_failure; 273 274 // It resets the mutator alloc region before new allocations can take place. 275 void init_mutator_alloc_region(); 276 277 // It releases the mutator alloc region. 278 void release_mutator_alloc_region(); 279 280 // It initializes the GC alloc regions at the start of a GC. 281 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 282 283 // It releases the GC alloc regions at the end of a GC. 284 void release_gc_alloc_regions(EvacuationInfo& evacuation_info); 285 286 // It does any cleanup that needs to be done on the GC alloc regions 287 // before a Full GC. 288 void abandon_gc_alloc_regions(); 289 290 // Helper for monitoring and management support. 291 G1MonitoringSupport* _g1mm; 292 293 // Records whether the region at the given index is (still) a 294 // candidate for eager reclaim. Only valid for humongous start 295 // regions; other regions have unspecified values. Humongous start 296 // regions are initialized at start of collection pause, with 297 // candidates removed from the set as they are found reachable from 298 // roots or the young generation. 299 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 300 protected: 301 bool default_value() const { return false; } 302 public: 303 void clear() { G1BiasedMappedArray<bool>::clear(); } 304 void set_candidate(uint region, bool value) { 305 set_by_index(region, value); 306 } 307 bool is_candidate(uint region) { 308 return get_by_index(region); 309 } 310 }; 311 312 HumongousReclaimCandidates _humongous_reclaim_candidates; 313 // Stores whether during humongous object registration we found candidate regions. 314 // If not, we can skip a few steps. 315 bool _has_humongous_reclaim_candidates; 316 317 volatile unsigned _gc_time_stamp; 318 319 size_t* _surviving_young_words; 320 321 G1HRPrinter _hr_printer; 322 323 void setup_surviving_young_words(); 324 void update_surviving_young_words(size_t* surv_young_words); 325 void cleanup_surviving_young_words(); 326 327 // It decides whether an explicit GC should start a concurrent cycle 328 // instead of doing a STW GC. Currently, a concurrent cycle is 329 // explicitly started if: 330 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 331 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 332 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 333 // (d) cause == _g1_humongous_allocation 334 bool should_do_concurrent_full_gc(GCCause::Cause cause); 335 336 // indicates whether we are in young or mixed GC mode 337 G1CollectorState _collector_state; 338 339 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 340 // concurrent cycles) we have started. 341 volatile uint _old_marking_cycles_started; 342 343 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 344 // concurrent cycles) we have completed. 345 volatile uint _old_marking_cycles_completed; 346 347 bool _heap_summary_sent; 348 349 // This is a non-product method that is helpful for testing. It is 350 // called at the end of a GC and artificially expands the heap by 351 // allocating a number of dead regions. This way we can induce very 352 // frequent marking cycles and stress the cleanup / concurrent 353 // cleanup code more (as all the regions that will be allocated by 354 // this method will be found dead by the marking cycle). 355 void allocate_dummy_regions() PRODUCT_RETURN; 356 357 // Clear RSets after a compaction. It also resets the GC time stamps. 358 void clear_rsets_post_compaction(); 359 360 // If the HR printer is active, dump the state of the regions in the 361 // heap after a compaction. 362 void print_hrm_post_compaction(); 363 364 // Create a memory mapper for auxiliary data structures of the given size and 365 // translation factor. 366 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 367 size_t size, 368 size_t translation_factor); 369 370 double verify(bool guard, const char* msg); 371 void verify_before_gc(); 372 void verify_after_gc(); 373 374 void log_gc_header(); 375 void log_gc_footer(double pause_time_sec); 376 377 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 378 379 // These are macros so that, if the assert fires, we get the correct 380 // line number, file, etc. 381 382 #define heap_locking_asserts_err_msg(_extra_message_) \ 383 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 384 (_extra_message_), \ 385 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 386 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 387 BOOL_TO_STR(Thread::current()->is_VM_thread())) 388 389 #define assert_heap_locked() \ 390 do { \ 391 assert(Heap_lock->owned_by_self(), \ 392 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 393 } while (0) 394 395 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 396 do { \ 397 assert(Heap_lock->owned_by_self() || \ 398 (SafepointSynchronize::is_at_safepoint() && \ 399 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 400 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 401 "should be at a safepoint")); \ 402 } while (0) 403 404 #define assert_heap_locked_and_not_at_safepoint() \ 405 do { \ 406 assert(Heap_lock->owned_by_self() && \ 407 !SafepointSynchronize::is_at_safepoint(), \ 408 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 409 "should not be at a safepoint")); \ 410 } while (0) 411 412 #define assert_heap_not_locked() \ 413 do { \ 414 assert(!Heap_lock->owned_by_self(), \ 415 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 416 } while (0) 417 418 #define assert_heap_not_locked_and_not_at_safepoint() \ 419 do { \ 420 assert(!Heap_lock->owned_by_self() && \ 421 !SafepointSynchronize::is_at_safepoint(), \ 422 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 423 "should not be at a safepoint")); \ 424 } while (0) 425 426 #define assert_at_safepoint(_should_be_vm_thread_) \ 427 do { \ 428 assert(SafepointSynchronize::is_at_safepoint() && \ 429 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 430 heap_locking_asserts_err_msg("should be at a safepoint")); \ 431 } while (0) 432 433 #define assert_not_at_safepoint() \ 434 do { \ 435 assert(!SafepointSynchronize::is_at_safepoint(), \ 436 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 437 } while (0) 438 439 protected: 440 441 // The young region list. 442 YoungList* _young_list; 443 444 // The current policy object for the collector. 445 G1CollectorPolicy* _g1_policy; 446 447 // This is the second level of trying to allocate a new region. If 448 // new_region() didn't find a region on the free_list, this call will 449 // check whether there's anything available on the 450 // secondary_free_list and/or wait for more regions to appear on 451 // that list, if _free_regions_coming is set. 452 HeapRegion* new_region_try_secondary_free_list(bool is_old); 453 454 // Try to allocate a single non-humongous HeapRegion sufficient for 455 // an allocation of the given word_size. If do_expand is true, 456 // attempt to expand the heap if necessary to satisfy the allocation 457 // request. If the region is to be used as an old region or for a 458 // humongous object, set is_old to true. If not, to false. 459 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 460 461 // Initialize a contiguous set of free regions of length num_regions 462 // and starting at index first so that they appear as a single 463 // humongous region. 464 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 465 uint num_regions, 466 size_t word_size, 467 AllocationContext_t context); 468 469 // Attempt to allocate a humongous object of the given size. Return 470 // NULL if unsuccessful. 471 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 472 473 // The following two methods, allocate_new_tlab() and 474 // mem_allocate(), are the two main entry points from the runtime 475 // into the G1's allocation routines. They have the following 476 // assumptions: 477 // 478 // * They should both be called outside safepoints. 479 // 480 // * They should both be called without holding the Heap_lock. 481 // 482 // * All allocation requests for new TLABs should go to 483 // allocate_new_tlab(). 484 // 485 // * All non-TLAB allocation requests should go to mem_allocate(). 486 // 487 // * If either call cannot satisfy the allocation request using the 488 // current allocating region, they will try to get a new one. If 489 // this fails, they will attempt to do an evacuation pause and 490 // retry the allocation. 491 // 492 // * If all allocation attempts fail, even after trying to schedule 493 // an evacuation pause, allocate_new_tlab() will return NULL, 494 // whereas mem_allocate() will attempt a heap expansion and/or 495 // schedule a Full GC. 496 // 497 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 498 // should never be called with word_size being humongous. All 499 // humongous allocation requests should go to mem_allocate() which 500 // will satisfy them with a special path. 501 502 virtual HeapWord* allocate_new_tlab(size_t word_size); 503 504 virtual HeapWord* mem_allocate(size_t word_size, 505 bool* gc_overhead_limit_was_exceeded); 506 507 // The following three methods take a gc_count_before_ret 508 // parameter which is used to return the GC count if the method 509 // returns NULL. Given that we are required to read the GC count 510 // while holding the Heap_lock, and these paths will take the 511 // Heap_lock at some point, it's easier to get them to read the GC 512 // count while holding the Heap_lock before they return NULL instead 513 // of the caller (namely: mem_allocate()) having to also take the 514 // Heap_lock just to read the GC count. 515 516 // First-level mutator allocation attempt: try to allocate out of 517 // the mutator alloc region without taking the Heap_lock. This 518 // should only be used for non-humongous allocations. 519 inline HeapWord* attempt_allocation(size_t word_size, 520 uint* gc_count_before_ret, 521 uint* gclocker_retry_count_ret); 522 523 // Second-level mutator allocation attempt: take the Heap_lock and 524 // retry the allocation attempt, potentially scheduling a GC 525 // pause. This should only be used for non-humongous allocations. 526 HeapWord* attempt_allocation_slow(size_t word_size, 527 AllocationContext_t context, 528 uint* gc_count_before_ret, 529 uint* gclocker_retry_count_ret); 530 531 // Takes the Heap_lock and attempts a humongous allocation. It can 532 // potentially schedule a GC pause. 533 HeapWord* attempt_allocation_humongous(size_t word_size, 534 uint* gc_count_before_ret, 535 uint* gclocker_retry_count_ret); 536 537 // Allocation attempt that should be called during safepoints (e.g., 538 // at the end of a successful GC). expect_null_mutator_alloc_region 539 // specifies whether the mutator alloc region is expected to be NULL 540 // or not. 541 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 542 AllocationContext_t context, 543 bool expect_null_mutator_alloc_region); 544 545 // It dirties the cards that cover the block so that so that the post 546 // write barrier never queues anything when updating objects on this 547 // block. It is assumed (and in fact we assert) that the block 548 // belongs to a young region. 549 inline void dirty_young_block(HeapWord* start, size_t word_size); 550 551 // Allocate blocks during garbage collection. Will ensure an 552 // allocation region, either by picking one or expanding the 553 // heap, and then allocate a block of the given size. The block 554 // may not be a humongous - it must fit into a single heap region. 555 inline HeapWord* par_allocate_during_gc(InCSetState dest, 556 size_t word_size, 557 AllocationContext_t context); 558 // Ensure that no further allocations can happen in "r", bearing in mind 559 // that parallel threads might be attempting allocations. 560 void par_allocate_remaining_space(HeapRegion* r); 561 562 // Allocation attempt during GC for a survivor object / PLAB. 563 inline HeapWord* survivor_attempt_allocation(size_t word_size, 564 AllocationContext_t context); 565 566 // Allocation attempt during GC for an old object / PLAB. 567 inline HeapWord* old_attempt_allocation(size_t word_size, 568 AllocationContext_t context); 569 570 // These methods are the "callbacks" from the G1AllocRegion class. 571 572 // For mutator alloc regions. 573 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 574 void retire_mutator_alloc_region(HeapRegion* alloc_region, 575 size_t allocated_bytes); 576 577 // For GC alloc regions. 578 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 579 InCSetState dest); 580 void retire_gc_alloc_region(HeapRegion* alloc_region, 581 size_t allocated_bytes, InCSetState dest); 582 583 // Allocate the highest free region in the reserved heap. This will commit 584 // regions as necessary. 585 HeapRegion* alloc_highest_free_region(); 586 587 // - if explicit_gc is true, the GC is for a System.gc() or a heap 588 // inspection request and should collect the entire heap 589 // - if clear_all_soft_refs is true, all soft references should be 590 // cleared during the GC 591 // - if explicit_gc is false, word_size describes the allocation that 592 // the GC should attempt (at least) to satisfy 593 // - it returns false if it is unable to do the collection due to the 594 // GC locker being active, true otherwise 595 bool do_collection(bool explicit_gc, 596 bool clear_all_soft_refs, 597 size_t word_size); 598 599 // Callback from VM_G1CollectFull operation. 600 // Perform a full collection. 601 virtual void do_full_collection(bool clear_all_soft_refs); 602 603 // Resize the heap if necessary after a full collection. If this is 604 // after a collect-for allocation, "word_size" is the allocation size, 605 // and will be considered part of the used portion of the heap. 606 void resize_if_necessary_after_full_collection(size_t word_size); 607 608 // Callback from VM_G1CollectForAllocation operation. 609 // This function does everything necessary/possible to satisfy a 610 // failed allocation request (including collection, expansion, etc.) 611 HeapWord* satisfy_failed_allocation(size_t word_size, 612 AllocationContext_t context, 613 bool* succeeded); 614 615 // Attempting to expand the heap sufficiently 616 // to support an allocation of the given "word_size". If 617 // successful, perform the allocation and return the address of the 618 // allocated block, or else "NULL". 619 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 620 621 // Process any reference objects discovered during 622 // an incremental evacuation pause. 623 void process_discovered_references(); 624 625 // Enqueue any remaining discovered references 626 // after processing. 627 void enqueue_discovered_references(); 628 629 public: 630 FlexibleWorkGang* workers() const { return _workers; } 631 632 G1Allocator* allocator() { 633 return _allocator; 634 } 635 636 G1MonitoringSupport* g1mm() { 637 assert(_g1mm != NULL, "should have been initialized"); 638 return _g1mm; 639 } 640 641 // Expand the garbage-first heap by at least the given size (in bytes!). 642 // Returns true if the heap was expanded by the requested amount; 643 // false otherwise. 644 // (Rounds up to a HeapRegion boundary.) 645 bool expand(size_t expand_bytes); 646 647 // Returns the PLAB statistics for a given destination. 648 inline PLABStats* alloc_buffer_stats(InCSetState dest); 649 650 // Determines PLAB size for a given destination. 651 inline size_t desired_plab_sz(InCSetState dest); 652 653 inline AllocationContextStats& allocation_context_stats(); 654 655 // Do anything common to GC's. 656 void gc_prologue(bool full); 657 void gc_epilogue(bool full); 658 659 // Modify the reclaim candidate set and test for presence. 660 // These are only valid for starts_humongous regions. 661 inline void set_humongous_reclaim_candidate(uint region, bool value); 662 inline bool is_humongous_reclaim_candidate(uint region); 663 664 // Remove from the reclaim candidate set. Also remove from the 665 // collection set so that later encounters avoid the slow path. 666 inline void set_humongous_is_live(oop obj); 667 668 // Register the given region to be part of the collection set. 669 inline void register_humongous_region_with_cset(uint index); 670 // Register regions with humongous objects (actually on the start region) in 671 // the in_cset_fast_test table. 672 void register_humongous_regions_with_cset(); 673 // We register a region with the fast "in collection set" test. We 674 // simply set to true the array slot corresponding to this region. 675 void register_young_region_with_cset(HeapRegion* r) { 676 _in_cset_fast_test.set_in_young(r->hrm_index()); 677 } 678 void register_old_region_with_cset(HeapRegion* r) { 679 _in_cset_fast_test.set_in_old(r->hrm_index()); 680 } 681 void clear_in_cset(const HeapRegion* hr) { 682 _in_cset_fast_test.clear(hr); 683 } 684 685 void clear_cset_fast_test() { 686 _in_cset_fast_test.clear(); 687 } 688 689 // This is called at the start of either a concurrent cycle or a Full 690 // GC to update the number of old marking cycles started. 691 void increment_old_marking_cycles_started(); 692 693 // This is called at the end of either a concurrent cycle or a Full 694 // GC to update the number of old marking cycles completed. Those two 695 // can happen in a nested fashion, i.e., we start a concurrent 696 // cycle, a Full GC happens half-way through it which ends first, 697 // and then the cycle notices that a Full GC happened and ends 698 // too. The concurrent parameter is a boolean to help us do a bit 699 // tighter consistency checking in the method. If concurrent is 700 // false, the caller is the inner caller in the nesting (i.e., the 701 // Full GC). If concurrent is true, the caller is the outer caller 702 // in this nesting (i.e., the concurrent cycle). Further nesting is 703 // not currently supported. The end of this call also notifies 704 // the FullGCCount_lock in case a Java thread is waiting for a full 705 // GC to happen (e.g., it called System.gc() with 706 // +ExplicitGCInvokesConcurrent). 707 void increment_old_marking_cycles_completed(bool concurrent); 708 709 uint old_marking_cycles_completed() { 710 return _old_marking_cycles_completed; 711 } 712 713 void register_concurrent_cycle_start(const Ticks& start_time); 714 void register_concurrent_cycle_end(); 715 void trace_heap_after_concurrent_cycle(); 716 717 G1HRPrinter* hr_printer() { return &_hr_printer; } 718 719 // Frees a non-humongous region by initializing its contents and 720 // adding it to the free list that's passed as a parameter (this is 721 // usually a local list which will be appended to the master free 722 // list later). The used bytes of freed regions are accumulated in 723 // pre_used. If par is true, the region's RSet will not be freed 724 // up. The assumption is that this will be done later. 725 // The locked parameter indicates if the caller has already taken 726 // care of proper synchronization. This may allow some optimizations. 727 void free_region(HeapRegion* hr, 728 FreeRegionList* free_list, 729 bool par, 730 bool locked = false); 731 732 // Frees a humongous region by collapsing it into individual regions 733 // and calling free_region() for each of them. The freed regions 734 // will be added to the free list that's passed as a parameter (this 735 // is usually a local list which will be appended to the master free 736 // list later). The used bytes of freed regions are accumulated in 737 // pre_used. If par is true, the region's RSet will not be freed 738 // up. The assumption is that this will be done later. 739 void free_humongous_region(HeapRegion* hr, 740 FreeRegionList* free_list, 741 bool par); 742 743 // Facility for allocating in 'archive' regions in high heap memory and 744 // recording the allocated ranges. These should all be called from the 745 // VM thread at safepoints, without the heap lock held. They can be used 746 // to create and archive a set of heap regions which can be mapped at the 747 // same fixed addresses in a subsequent JVM invocation. 748 void begin_archive_alloc_range(); 749 750 // Check if the requested size would be too large for an archive allocation. 751 bool is_archive_alloc_too_large(size_t word_size); 752 753 // Allocate memory of the requested size from the archive region. This will 754 // return NULL if the size is too large or if no memory is available. It 755 // does not trigger a garbage collection. 756 HeapWord* archive_mem_allocate(size_t word_size); 757 758 // Optionally aligns the end address and returns the allocated ranges in 759 // an array of MemRegions in order of ascending addresses. 760 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 761 size_t end_alignment_in_bytes = 0); 762 763 // Facility for allocating a fixed range within the heap and marking 764 // the containing regions as 'archive'. For use at JVM init time, when the 765 // caller may mmap archived heap data at the specified range(s). 766 // Verify that the MemRegions specified in the argument array are within the 767 // reserved heap. 768 bool check_archive_addresses(MemRegion* range, size_t count); 769 770 // Commit the appropriate G1 regions containing the specified MemRegions 771 // and mark them as 'archive' regions. The regions in the array must be 772 // non-overlapping and in order of ascending address. 773 bool alloc_archive_regions(MemRegion* range, size_t count); 774 775 // Insert any required filler objects in the G1 regions around the specified 776 // ranges to make the regions parseable. This must be called after 777 // alloc_archive_regions, and after class loading has occurred. 778 void fill_archive_regions(MemRegion* range, size_t count); 779 780 protected: 781 782 // Shrink the garbage-first heap by at most the given size (in bytes!). 783 // (Rounds down to a HeapRegion boundary.) 784 virtual void shrink(size_t expand_bytes); 785 void shrink_helper(size_t expand_bytes); 786 787 #if TASKQUEUE_STATS 788 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 789 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 790 void reset_taskqueue_stats(); 791 #endif // TASKQUEUE_STATS 792 793 // Schedule the VM operation that will do an evacuation pause to 794 // satisfy an allocation request of word_size. *succeeded will 795 // return whether the VM operation was successful (it did do an 796 // evacuation pause) or not (another thread beat us to it or the GC 797 // locker was active). Given that we should not be holding the 798 // Heap_lock when we enter this method, we will pass the 799 // gc_count_before (i.e., total_collections()) as a parameter since 800 // it has to be read while holding the Heap_lock. Currently, both 801 // methods that call do_collection_pause() release the Heap_lock 802 // before the call, so it's easy to read gc_count_before just before. 803 HeapWord* do_collection_pause(size_t word_size, 804 uint gc_count_before, 805 bool* succeeded, 806 GCCause::Cause gc_cause); 807 808 void wait_for_root_region_scanning(); 809 810 // The guts of the incremental collection pause, executed by the vm 811 // thread. It returns false if it is unable to do the collection due 812 // to the GC locker being active, true otherwise 813 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 814 815 // Actually do the work of evacuating the collection set. 816 void evacuate_collection_set(EvacuationInfo& evacuation_info); 817 818 // The g1 remembered set of the heap. 819 G1RemSet* _g1_rem_set; 820 821 // A set of cards that cover the objects for which the Rsets should be updated 822 // concurrently after the collection. 823 DirtyCardQueueSet _dirty_card_queue_set; 824 825 // The closure used to refine a single card. 826 RefineCardTableEntryClosure* _refine_cte_cl; 827 828 // A DirtyCardQueueSet that is used to hold cards that contain 829 // references into the current collection set. This is used to 830 // update the remembered sets of the regions in the collection 831 // set in the event of an evacuation failure. 832 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 833 834 // After a collection pause, make the regions in the CS into free 835 // regions. 836 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 837 838 // Abandon the current collection set without recording policy 839 // statistics or updating free lists. 840 void abandon_collection_set(HeapRegion* cs_head); 841 842 // The concurrent marker (and the thread it runs in.) 843 ConcurrentMark* _cm; 844 ConcurrentMarkThread* _cmThread; 845 846 // The concurrent refiner. 847 ConcurrentG1Refine* _cg1r; 848 849 // The parallel task queues 850 RefToScanQueueSet *_task_queues; 851 852 // True iff a evacuation has failed in the current collection. 853 bool _evacuation_failed; 854 855 EvacuationFailedInfo* _evacuation_failed_info_array; 856 857 // Failed evacuations cause some logical from-space objects to have 858 // forwarding pointers to themselves. Reset them. 859 void remove_self_forwarding_pointers(); 860 861 struct OopAndMarkOop { 862 private: 863 oop _o; 864 markOop _m; 865 public: 866 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { 867 } 868 869 void set_mark() { 870 _o->set_mark(_m); 871 } 872 }; 873 874 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack; 875 // Stores marks with the corresponding oop that we need to preserve during evacuation 876 // failure. 877 OopAndMarkOopStack* _preserved_objs; 878 879 // Preserve the mark of "obj", if necessary, in preparation for its mark 880 // word being overwritten with a self-forwarding-pointer. 881 void preserve_mark_during_evac_failure(uint queue, oop obj, markOop m); 882 883 #ifndef PRODUCT 884 // Support for forcing evacuation failures. Analogous to 885 // PromotionFailureALot for the other collectors. 886 887 // Records whether G1EvacuationFailureALot should be in effect 888 // for the current GC 889 bool _evacuation_failure_alot_for_current_gc; 890 891 // Used to record the GC number for interval checking when 892 // determining whether G1EvaucationFailureALot is in effect 893 // for the current GC. 894 size_t _evacuation_failure_alot_gc_number; 895 896 // Count of the number of evacuations between failures. 897 volatile size_t _evacuation_failure_alot_count; 898 899 // Set whether G1EvacuationFailureALot should be in effect 900 // for the current GC (based upon the type of GC and which 901 // command line flags are set); 902 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 903 bool during_initial_mark, 904 bool during_marking); 905 906 inline void set_evacuation_failure_alot_for_current_gc(); 907 908 // Return true if it's time to cause an evacuation failure. 909 inline bool evacuation_should_fail(); 910 911 // Reset the G1EvacuationFailureALot counters. Should be called at 912 // the end of an evacuation pause in which an evacuation failure occurred. 913 inline void reset_evacuation_should_fail(); 914 #endif // !PRODUCT 915 916 // ("Weak") Reference processing support. 917 // 918 // G1 has 2 instances of the reference processor class. One 919 // (_ref_processor_cm) handles reference object discovery 920 // and subsequent processing during concurrent marking cycles. 921 // 922 // The other (_ref_processor_stw) handles reference object 923 // discovery and processing during full GCs and incremental 924 // evacuation pauses. 925 // 926 // During an incremental pause, reference discovery will be 927 // temporarily disabled for _ref_processor_cm and will be 928 // enabled for _ref_processor_stw. At the end of the evacuation 929 // pause references discovered by _ref_processor_stw will be 930 // processed and discovery will be disabled. The previous 931 // setting for reference object discovery for _ref_processor_cm 932 // will be re-instated. 933 // 934 // At the start of marking: 935 // * Discovery by the CM ref processor is verified to be inactive 936 // and it's discovered lists are empty. 937 // * Discovery by the CM ref processor is then enabled. 938 // 939 // At the end of marking: 940 // * Any references on the CM ref processor's discovered 941 // lists are processed (possibly MT). 942 // 943 // At the start of full GC we: 944 // * Disable discovery by the CM ref processor and 945 // empty CM ref processor's discovered lists 946 // (without processing any entries). 947 // * Verify that the STW ref processor is inactive and it's 948 // discovered lists are empty. 949 // * Temporarily set STW ref processor discovery as single threaded. 950 // * Temporarily clear the STW ref processor's _is_alive_non_header 951 // field. 952 // * Finally enable discovery by the STW ref processor. 953 // 954 // The STW ref processor is used to record any discovered 955 // references during the full GC. 956 // 957 // At the end of a full GC we: 958 // * Enqueue any reference objects discovered by the STW ref processor 959 // that have non-live referents. This has the side-effect of 960 // making the STW ref processor inactive by disabling discovery. 961 // * Verify that the CM ref processor is still inactive 962 // and no references have been placed on it's discovered 963 // lists (also checked as a precondition during initial marking). 964 965 // The (stw) reference processor... 966 ReferenceProcessor* _ref_processor_stw; 967 968 STWGCTimer* _gc_timer_stw; 969 ConcurrentGCTimer* _gc_timer_cm; 970 971 G1OldTracer* _gc_tracer_cm; 972 G1NewTracer* _gc_tracer_stw; 973 974 // During reference object discovery, the _is_alive_non_header 975 // closure (if non-null) is applied to the referent object to 976 // determine whether the referent is live. If so then the 977 // reference object does not need to be 'discovered' and can 978 // be treated as a regular oop. This has the benefit of reducing 979 // the number of 'discovered' reference objects that need to 980 // be processed. 981 // 982 // Instance of the is_alive closure for embedding into the 983 // STW reference processor as the _is_alive_non_header field. 984 // Supplying a value for the _is_alive_non_header field is 985 // optional but doing so prevents unnecessary additions to 986 // the discovered lists during reference discovery. 987 G1STWIsAliveClosure _is_alive_closure_stw; 988 989 // The (concurrent marking) reference processor... 990 ReferenceProcessor* _ref_processor_cm; 991 992 // Instance of the concurrent mark is_alive closure for embedding 993 // into the Concurrent Marking reference processor as the 994 // _is_alive_non_header field. Supplying a value for the 995 // _is_alive_non_header field is optional but doing so prevents 996 // unnecessary additions to the discovered lists during reference 997 // discovery. 998 G1CMIsAliveClosure _is_alive_closure_cm; 999 1000 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1001 HeapRegion** _worker_cset_start_region; 1002 1003 // Time stamp to validate the regions recorded in the cache 1004 // used by G1CollectedHeap::start_cset_region_for_worker(). 1005 // The heap region entry for a given worker is valid iff 1006 // the associated time stamp value matches the current value 1007 // of G1CollectedHeap::_gc_time_stamp. 1008 uint* _worker_cset_start_region_time_stamp; 1009 1010 volatile bool _free_regions_coming; 1011 1012 public: 1013 1014 void set_refine_cte_cl_concurrency(bool concurrent); 1015 1016 RefToScanQueue *task_queue(uint i) const; 1017 1018 uint num_task_queues() const; 1019 1020 // A set of cards where updates happened during the GC 1021 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1022 1023 // A DirtyCardQueueSet that is used to hold cards that contain 1024 // references into the current collection set. This is used to 1025 // update the remembered sets of the regions in the collection 1026 // set in the event of an evacuation failure. 1027 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1028 { return _into_cset_dirty_card_queue_set; } 1029 1030 // Create a G1CollectedHeap with the specified policy. 1031 // Must call the initialize method afterwards. 1032 // May not return if something goes wrong. 1033 G1CollectedHeap(G1CollectorPolicy* policy); 1034 1035 // Initialize the G1CollectedHeap to have the initial and 1036 // maximum sizes and remembered and barrier sets 1037 // specified by the policy object. 1038 jint initialize(); 1039 1040 virtual void stop(); 1041 1042 // Return the (conservative) maximum heap alignment for any G1 heap 1043 static size_t conservative_max_heap_alignment(); 1044 1045 // Does operations required after initialization has been done. 1046 void post_initialize(); 1047 1048 // Initialize weak reference processing. 1049 void ref_processing_init(); 1050 1051 virtual Name kind() const { 1052 return CollectedHeap::G1CollectedHeap; 1053 } 1054 1055 G1CollectorState* collector_state() { return &_collector_state; } 1056 1057 // The current policy object for the collector. 1058 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1059 1060 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1061 1062 // Adaptive size policy. No such thing for g1. 1063 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1064 1065 // The rem set and barrier set. 1066 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1067 1068 unsigned get_gc_time_stamp() { 1069 return _gc_time_stamp; 1070 } 1071 1072 inline void reset_gc_time_stamp(); 1073 1074 void check_gc_time_stamps() PRODUCT_RETURN; 1075 1076 inline void increment_gc_time_stamp(); 1077 1078 // Reset the given region's GC timestamp. If it's starts humongous, 1079 // also reset the GC timestamp of its corresponding 1080 // continues humongous regions too. 1081 void reset_gc_time_stamps(HeapRegion* hr); 1082 1083 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1084 DirtyCardQueue* into_cset_dcq, 1085 bool concurrent, uint worker_i); 1086 1087 // The shared block offset table array. 1088 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1089 1090 // Reference Processing accessors 1091 1092 // The STW reference processor.... 1093 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1094 1095 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1096 1097 // The Concurrent Marking reference processor... 1098 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1099 1100 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1101 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1102 1103 virtual size_t capacity() const; 1104 virtual size_t used() const; 1105 // This should be called when we're not holding the heap lock. The 1106 // result might be a bit inaccurate. 1107 size_t used_unlocked() const; 1108 size_t recalculate_used() const; 1109 1110 // These virtual functions do the actual allocation. 1111 // Some heaps may offer a contiguous region for shared non-blocking 1112 // allocation, via inlined code (by exporting the address of the top and 1113 // end fields defining the extent of the contiguous allocation region.) 1114 // But G1CollectedHeap doesn't yet support this. 1115 1116 virtual bool is_maximal_no_gc() const { 1117 return _hrm.available() == 0; 1118 } 1119 1120 // The current number of regions in the heap. 1121 uint num_regions() const { return _hrm.length(); } 1122 1123 // The max number of regions in the heap. 1124 uint max_regions() const { return _hrm.max_length(); } 1125 1126 // The number of regions that are completely free. 1127 uint num_free_regions() const { return _hrm.num_free_regions(); } 1128 1129 MemoryUsage get_auxiliary_data_memory_usage() const { 1130 return _hrm.get_auxiliary_data_memory_usage(); 1131 } 1132 1133 // The number of regions that are not completely free. 1134 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1135 1136 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1137 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1138 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1139 void verify_dirty_young_regions() PRODUCT_RETURN; 1140 1141 #ifndef PRODUCT 1142 // Make sure that the given bitmap has no marked objects in the 1143 // range [from,limit). If it does, print an error message and return 1144 // false. Otherwise, just return true. bitmap_name should be "prev" 1145 // or "next". 1146 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1147 HeapWord* from, HeapWord* limit); 1148 1149 // Verify that the prev / next bitmap range [tams,end) for the given 1150 // region has no marks. Return true if all is well, false if errors 1151 // are detected. 1152 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1153 #endif // PRODUCT 1154 1155 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1156 // the given region do not have any spurious marks. If errors are 1157 // detected, print appropriate error messages and crash. 1158 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1159 1160 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1161 // have any spurious marks. If errors are detected, print 1162 // appropriate error messages and crash. 1163 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1164 1165 // Do sanity check on the contents of the in-cset fast test table. 1166 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1167 1168 // verify_region_sets() performs verification over the region 1169 // lists. It will be compiled in the product code to be used when 1170 // necessary (i.e., during heap verification). 1171 void verify_region_sets(); 1172 1173 // verify_region_sets_optional() is planted in the code for 1174 // list verification in non-product builds (and it can be enabled in 1175 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1176 #if HEAP_REGION_SET_FORCE_VERIFY 1177 void verify_region_sets_optional() { 1178 verify_region_sets(); 1179 } 1180 #else // HEAP_REGION_SET_FORCE_VERIFY 1181 void verify_region_sets_optional() { } 1182 #endif // HEAP_REGION_SET_FORCE_VERIFY 1183 1184 #ifdef ASSERT 1185 bool is_on_master_free_list(HeapRegion* hr) { 1186 return _hrm.is_free(hr); 1187 } 1188 #endif // ASSERT 1189 1190 // Wrapper for the region list operations that can be called from 1191 // methods outside this class. 1192 1193 void secondary_free_list_add(FreeRegionList* list) { 1194 _secondary_free_list.add_ordered(list); 1195 } 1196 1197 void append_secondary_free_list() { 1198 _hrm.insert_list_into_free_list(&_secondary_free_list); 1199 } 1200 1201 void append_secondary_free_list_if_not_empty_with_lock() { 1202 // If the secondary free list looks empty there's no reason to 1203 // take the lock and then try to append it. 1204 if (!_secondary_free_list.is_empty()) { 1205 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1206 append_secondary_free_list(); 1207 } 1208 } 1209 1210 inline void old_set_remove(HeapRegion* hr); 1211 1212 size_t non_young_capacity_bytes() { 1213 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1214 } 1215 1216 void set_free_regions_coming(); 1217 void reset_free_regions_coming(); 1218 bool free_regions_coming() { return _free_regions_coming; } 1219 void wait_while_free_regions_coming(); 1220 1221 // Determine whether the given region is one that we are using as an 1222 // old GC alloc region. 1223 bool is_old_gc_alloc_region(HeapRegion* hr) { 1224 return _allocator->is_retained_old_region(hr); 1225 } 1226 1227 // Perform a collection of the heap; intended for use in implementing 1228 // "System.gc". This probably implies as full a collection as the 1229 // "CollectedHeap" supports. 1230 virtual void collect(GCCause::Cause cause); 1231 1232 // The same as above but assume that the caller holds the Heap_lock. 1233 void collect_locked(GCCause::Cause cause); 1234 1235 virtual bool copy_allocation_context_stats(const jint* contexts, 1236 jlong* totals, 1237 jbyte* accuracy, 1238 jint len); 1239 1240 // True iff an evacuation has failed in the most-recent collection. 1241 bool evacuation_failed() { return _evacuation_failed; } 1242 1243 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1244 void prepend_to_freelist(FreeRegionList* list); 1245 void decrement_summary_bytes(size_t bytes); 1246 1247 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1248 virtual bool is_in(const void* p) const; 1249 #ifdef ASSERT 1250 // Returns whether p is in one of the available areas of the heap. Slow but 1251 // extensive version. 1252 bool is_in_exact(const void* p) const; 1253 #endif 1254 1255 // Return "TRUE" iff the given object address is within the collection 1256 // set. Slow implementation. 1257 inline bool obj_in_cs(oop obj); 1258 1259 inline bool is_in_cset(const HeapRegion *hr); 1260 inline bool is_in_cset(oop obj); 1261 1262 inline bool is_in_cset_or_humongous(const oop obj); 1263 1264 private: 1265 // This array is used for a quick test on whether a reference points into 1266 // the collection set or not. Each of the array's elements denotes whether the 1267 // corresponding region is in the collection set or not. 1268 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1269 1270 public: 1271 1272 inline InCSetState in_cset_state(const oop obj); 1273 1274 // Return "TRUE" iff the given object address is in the reserved 1275 // region of g1. 1276 bool is_in_g1_reserved(const void* p) const { 1277 return _hrm.reserved().contains(p); 1278 } 1279 1280 // Returns a MemRegion that corresponds to the space that has been 1281 // reserved for the heap 1282 MemRegion g1_reserved() const { 1283 return _hrm.reserved(); 1284 } 1285 1286 virtual bool is_in_closed_subset(const void* p) const; 1287 1288 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1289 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1290 } 1291 1292 // This resets the card table to all zeros. It is used after 1293 // a collection pause which used the card table to claim cards. 1294 void cleanUpCardTable(); 1295 1296 // Iteration functions. 1297 1298 // Iterate over all objects, calling "cl.do_object" on each. 1299 virtual void object_iterate(ObjectClosure* cl); 1300 1301 virtual void safe_object_iterate(ObjectClosure* cl) { 1302 object_iterate(cl); 1303 } 1304 1305 // Iterate over heap regions, in address order, terminating the 1306 // iteration early if the "doHeapRegion" method returns "true". 1307 void heap_region_iterate(HeapRegionClosure* blk) const; 1308 1309 // Return the region with the given index. It assumes the index is valid. 1310 inline HeapRegion* region_at(uint index) const; 1311 1312 // Calculate the region index of the given address. Given address must be 1313 // within the heap. 1314 inline uint addr_to_region(HeapWord* addr) const; 1315 1316 inline HeapWord* bottom_addr_for_region(uint index) const; 1317 1318 // Iterate over the heap regions in parallel. Assumes that this will be called 1319 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1320 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1321 // to each of the regions, by attempting to claim the region using the 1322 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1323 // region. The concurrent argument should be set to true if iteration is 1324 // performed concurrently, during which no assumptions are made for consistent 1325 // attributes of the heap regions (as they might be modified while iterating). 1326 void heap_region_par_iterate(HeapRegionClosure* cl, 1327 uint worker_id, 1328 HeapRegionClaimer* hrclaimer, 1329 bool concurrent = false) const; 1330 1331 // Clear the cached cset start regions and (more importantly) 1332 // the time stamps. Called when we reset the GC time stamp. 1333 void clear_cset_start_regions(); 1334 1335 // Given the id of a worker, obtain or calculate a suitable 1336 // starting region for iterating over the current collection set. 1337 HeapRegion* start_cset_region_for_worker(uint worker_i); 1338 1339 // Iterate over the regions (if any) in the current collection set. 1340 void collection_set_iterate(HeapRegionClosure* blk); 1341 1342 // As above but starting from region r 1343 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1344 1345 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1346 1347 // Returns the HeapRegion that contains addr. addr must not be NULL. 1348 template <class T> 1349 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1350 1351 // Returns the HeapRegion that contains addr. addr must not be NULL. 1352 // If addr is within a humongous continues region, it returns its humongous start region. 1353 template <class T> 1354 inline HeapRegion* heap_region_containing(const T addr) const; 1355 1356 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1357 // each address in the (reserved) heap is a member of exactly 1358 // one block. The defining characteristic of a block is that it is 1359 // possible to find its size, and thus to progress forward to the next 1360 // block. (Blocks may be of different sizes.) Thus, blocks may 1361 // represent Java objects, or they might be free blocks in a 1362 // free-list-based heap (or subheap), as long as the two kinds are 1363 // distinguishable and the size of each is determinable. 1364 1365 // Returns the address of the start of the "block" that contains the 1366 // address "addr". We say "blocks" instead of "object" since some heaps 1367 // may not pack objects densely; a chunk may either be an object or a 1368 // non-object. 1369 virtual HeapWord* block_start(const void* addr) const; 1370 1371 // Requires "addr" to be the start of a chunk, and returns its size. 1372 // "addr + size" is required to be the start of a new chunk, or the end 1373 // of the active area of the heap. 1374 virtual size_t block_size(const HeapWord* addr) const; 1375 1376 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1377 // the block is an object. 1378 virtual bool block_is_obj(const HeapWord* addr) const; 1379 1380 // Section on thread-local allocation buffers (TLABs) 1381 // See CollectedHeap for semantics. 1382 1383 bool supports_tlab_allocation() const; 1384 size_t tlab_capacity(Thread* ignored) const; 1385 size_t tlab_used(Thread* ignored) const; 1386 size_t max_tlab_size() const; 1387 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1388 1389 // Can a compiler initialize a new object without store barriers? 1390 // This permission only extends from the creation of a new object 1391 // via a TLAB up to the first subsequent safepoint. If such permission 1392 // is granted for this heap type, the compiler promises to call 1393 // defer_store_barrier() below on any slow path allocation of 1394 // a new object for which such initializing store barriers will 1395 // have been elided. G1, like CMS, allows this, but should be 1396 // ready to provide a compensating write barrier as necessary 1397 // if that storage came out of a non-young region. The efficiency 1398 // of this implementation depends crucially on being able to 1399 // answer very efficiently in constant time whether a piece of 1400 // storage in the heap comes from a young region or not. 1401 // See ReduceInitialCardMarks. 1402 virtual bool can_elide_tlab_store_barriers() const { 1403 return true; 1404 } 1405 1406 virtual bool card_mark_must_follow_store() const { 1407 return true; 1408 } 1409 1410 inline bool is_in_young(const oop obj); 1411 1412 virtual bool is_scavengable(const void* addr); 1413 1414 // We don't need barriers for initializing stores to objects 1415 // in the young gen: for the SATB pre-barrier, there is no 1416 // pre-value that needs to be remembered; for the remembered-set 1417 // update logging post-barrier, we don't maintain remembered set 1418 // information for young gen objects. 1419 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1420 1421 // Returns "true" iff the given word_size is "very large". 1422 static bool is_humongous(size_t word_size) { 1423 // Note this has to be strictly greater-than as the TLABs 1424 // are capped at the humongous threshold and we want to 1425 // ensure that we don't try to allocate a TLAB as 1426 // humongous and that we don't allocate a humongous 1427 // object in a TLAB. 1428 return word_size > _humongous_object_threshold_in_words; 1429 } 1430 1431 // Returns the humongous threshold for a specific region size 1432 static size_t humongous_threshold_for(size_t region_size) { 1433 return (region_size / 2); 1434 } 1435 1436 // Update mod union table with the set of dirty cards. 1437 void updateModUnion(); 1438 1439 // Set the mod union bits corresponding to the given memRegion. Note 1440 // that this is always a safe operation, since it doesn't clear any 1441 // bits. 1442 void markModUnionRange(MemRegion mr); 1443 1444 // Print the maximum heap capacity. 1445 virtual size_t max_capacity() const; 1446 1447 virtual jlong millis_since_last_gc(); 1448 1449 1450 // Convenience function to be used in situations where the heap type can be 1451 // asserted to be this type. 1452 static G1CollectedHeap* heap(); 1453 1454 void set_region_short_lived_locked(HeapRegion* hr); 1455 // add appropriate methods for any other surv rate groups 1456 1457 YoungList* young_list() const { return _young_list; } 1458 1459 // debugging 1460 bool check_young_list_well_formed() { 1461 return _young_list->check_list_well_formed(); 1462 } 1463 1464 bool check_young_list_empty(bool check_heap, 1465 bool check_sample = true); 1466 1467 // *** Stuff related to concurrent marking. It's not clear to me that so 1468 // many of these need to be public. 1469 1470 // The functions below are helper functions that a subclass of 1471 // "CollectedHeap" can use in the implementation of its virtual 1472 // functions. 1473 // This performs a concurrent marking of the live objects in a 1474 // bitmap off to the side. 1475 void doConcurrentMark(); 1476 1477 bool isMarkedPrev(oop obj) const; 1478 bool isMarkedNext(oop obj) const; 1479 1480 // Determine if an object is dead, given the object and also 1481 // the region to which the object belongs. An object is dead 1482 // iff a) it was not allocated since the last mark, b) it 1483 // is not marked, and c) it is not in an archive region. 1484 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1485 return 1486 !hr->obj_allocated_since_prev_marking(obj) && 1487 !isMarkedPrev(obj) && 1488 !hr->is_archive(); 1489 } 1490 1491 // This function returns true when an object has been 1492 // around since the previous marking and hasn't yet 1493 // been marked during this marking, and is not in an archive region. 1494 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1495 return 1496 !hr->obj_allocated_since_next_marking(obj) && 1497 !isMarkedNext(obj) && 1498 !hr->is_archive(); 1499 } 1500 1501 // Determine if an object is dead, given only the object itself. 1502 // This will find the region to which the object belongs and 1503 // then call the region version of the same function. 1504 1505 // Added if it is NULL it isn't dead. 1506 1507 inline bool is_obj_dead(const oop obj) const; 1508 1509 inline bool is_obj_ill(const oop obj) const; 1510 1511 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1512 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1513 bool is_marked(oop obj, VerifyOption vo); 1514 const char* top_at_mark_start_str(VerifyOption vo); 1515 1516 ConcurrentMark* concurrent_mark() const { return _cm; } 1517 1518 // Refinement 1519 1520 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1521 1522 // The dirty cards region list is used to record a subset of regions 1523 // whose cards need clearing. The list if populated during the 1524 // remembered set scanning and drained during the card table 1525 // cleanup. Although the methods are reentrant, population/draining 1526 // phases must not overlap. For synchronization purposes the last 1527 // element on the list points to itself. 1528 HeapRegion* _dirty_cards_region_list; 1529 void push_dirty_cards_region(HeapRegion* hr); 1530 HeapRegion* pop_dirty_cards_region(); 1531 1532 // Optimized nmethod scanning support routines 1533 1534 // Register the given nmethod with the G1 heap. 1535 virtual void register_nmethod(nmethod* nm); 1536 1537 // Unregister the given nmethod from the G1 heap. 1538 virtual void unregister_nmethod(nmethod* nm); 1539 1540 // Free up superfluous code root memory. 1541 void purge_code_root_memory(); 1542 1543 // Rebuild the strong code root lists for each region 1544 // after a full GC. 1545 void rebuild_strong_code_roots(); 1546 1547 // Delete entries for dead interned string and clean up unreferenced symbols 1548 // in symbol table, possibly in parallel. 1549 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1550 1551 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1552 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1553 1554 // Redirty logged cards in the refinement queue. 1555 void redirty_logged_cards(); 1556 // Verification 1557 1558 // Perform any cleanup actions necessary before allowing a verification. 1559 virtual void prepare_for_verify(); 1560 1561 // Perform verification. 1562 1563 // vo == UsePrevMarking -> use "prev" marking information, 1564 // vo == UseNextMarking -> use "next" marking information 1565 // vo == UseMarkWord -> use the mark word in the object header 1566 // 1567 // NOTE: Only the "prev" marking information is guaranteed to be 1568 // consistent most of the time, so most calls to this should use 1569 // vo == UsePrevMarking. 1570 // Currently, there is only one case where this is called with 1571 // vo == UseNextMarking, which is to verify the "next" marking 1572 // information at the end of remark. 1573 // Currently there is only one place where this is called with 1574 // vo == UseMarkWord, which is to verify the marking during a 1575 // full GC. 1576 void verify(bool silent, VerifyOption vo); 1577 1578 // Override; it uses the "prev" marking information 1579 virtual void verify(bool silent); 1580 1581 // The methods below are here for convenience and dispatch the 1582 // appropriate method depending on value of the given VerifyOption 1583 // parameter. The values for that parameter, and their meanings, 1584 // are the same as those above. 1585 1586 bool is_obj_dead_cond(const oop obj, 1587 const HeapRegion* hr, 1588 const VerifyOption vo) const; 1589 1590 bool is_obj_dead_cond(const oop obj, 1591 const VerifyOption vo) const; 1592 1593 G1HeapSummary create_g1_heap_summary(); 1594 1595 // Printing 1596 1597 virtual void print_on(outputStream* st) const; 1598 virtual void print_extended_on(outputStream* st) const; 1599 virtual void print_on_error(outputStream* st) const; 1600 1601 virtual void print_gc_threads_on(outputStream* st) const; 1602 virtual void gc_threads_do(ThreadClosure* tc) const; 1603 1604 // Override 1605 void print_tracing_info() const; 1606 1607 // The following two methods are helpful for debugging RSet issues. 1608 void print_cset_rsets() PRODUCT_RETURN; 1609 void print_all_rsets() PRODUCT_RETURN; 1610 1611 public: 1612 size_t pending_card_num(); 1613 size_t cards_scanned(); 1614 1615 protected: 1616 size_t _max_heap_capacity; 1617 }; 1618 1619 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP