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 // Together, these store an object with a preserved mark, and its mark value. 862 Stack<oop, mtGC> _objs_with_preserved_marks; 863 Stack<markOop, mtGC> _preserved_marks_of_objs; 864 865 // Preserve the mark of "obj", if necessary, in preparation for its mark 866 // word being overwritten with a self-forwarding-pointer. 867 void preserve_mark_if_necessary(oop obj, markOop m); 868 869 // The stack of evac-failure objects left to be scanned. 870 GrowableArray<oop>* _evac_failure_scan_stack; 871 // The closure to apply to evac-failure objects. 872 873 OopsInHeapRegionClosure* _evac_failure_closure; 874 // Set the field above. 875 void 876 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 877 _evac_failure_closure = evac_failure_closure; 878 } 879 880 // Push "obj" on the scan stack. 881 void push_on_evac_failure_scan_stack(oop obj); 882 // Process scan stack entries until the stack is empty. 883 void drain_evac_failure_scan_stack(); 884 // True iff an invocation of "drain_scan_stack" is in progress; to 885 // prevent unnecessary recursion. 886 bool _drain_in_progress; 887 888 // Do any necessary initialization for evacuation-failure handling. 889 // "cl" is the closure that will be used to process evac-failure 890 // objects. 891 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 892 // Do any necessary cleanup for evacuation-failure handling data 893 // structures. 894 void finalize_for_evac_failure(); 895 896 // An attempt to evacuate "obj" has failed; take necessary steps. 897 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 898 void handle_evacuation_failure_common(oop obj, markOop m); 899 900 #ifndef PRODUCT 901 // Support for forcing evacuation failures. Analogous to 902 // PromotionFailureALot for the other collectors. 903 904 // Records whether G1EvacuationFailureALot should be in effect 905 // for the current GC 906 bool _evacuation_failure_alot_for_current_gc; 907 908 // Used to record the GC number for interval checking when 909 // determining whether G1EvaucationFailureALot is in effect 910 // for the current GC. 911 size_t _evacuation_failure_alot_gc_number; 912 913 // Count of the number of evacuations between failures. 914 volatile size_t _evacuation_failure_alot_count; 915 916 // Set whether G1EvacuationFailureALot should be in effect 917 // for the current GC (based upon the type of GC and which 918 // command line flags are set); 919 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 920 bool during_initial_mark, 921 bool during_marking); 922 923 inline void set_evacuation_failure_alot_for_current_gc(); 924 925 // Return true if it's time to cause an evacuation failure. 926 inline bool evacuation_should_fail(); 927 928 // Reset the G1EvacuationFailureALot counters. Should be called at 929 // the end of an evacuation pause in which an evacuation failure occurred. 930 inline void reset_evacuation_should_fail(); 931 #endif // !PRODUCT 932 933 // ("Weak") Reference processing support. 934 // 935 // G1 has 2 instances of the reference processor class. One 936 // (_ref_processor_cm) handles reference object discovery 937 // and subsequent processing during concurrent marking cycles. 938 // 939 // The other (_ref_processor_stw) handles reference object 940 // discovery and processing during full GCs and incremental 941 // evacuation pauses. 942 // 943 // During an incremental pause, reference discovery will be 944 // temporarily disabled for _ref_processor_cm and will be 945 // enabled for _ref_processor_stw. At the end of the evacuation 946 // pause references discovered by _ref_processor_stw will be 947 // processed and discovery will be disabled. The previous 948 // setting for reference object discovery for _ref_processor_cm 949 // will be re-instated. 950 // 951 // At the start of marking: 952 // * Discovery by the CM ref processor is verified to be inactive 953 // and it's discovered lists are empty. 954 // * Discovery by the CM ref processor is then enabled. 955 // 956 // At the end of marking: 957 // * Any references on the CM ref processor's discovered 958 // lists are processed (possibly MT). 959 // 960 // At the start of full GC we: 961 // * Disable discovery by the CM ref processor and 962 // empty CM ref processor's discovered lists 963 // (without processing any entries). 964 // * Verify that the STW ref processor is inactive and it's 965 // discovered lists are empty. 966 // * Temporarily set STW ref processor discovery as single threaded. 967 // * Temporarily clear the STW ref processor's _is_alive_non_header 968 // field. 969 // * Finally enable discovery by the STW ref processor. 970 // 971 // The STW ref processor is used to record any discovered 972 // references during the full GC. 973 // 974 // At the end of a full GC we: 975 // * Enqueue any reference objects discovered by the STW ref processor 976 // that have non-live referents. This has the side-effect of 977 // making the STW ref processor inactive by disabling discovery. 978 // * Verify that the CM ref processor is still inactive 979 // and no references have been placed on it's discovered 980 // lists (also checked as a precondition during initial marking). 981 982 // The (stw) reference processor... 983 ReferenceProcessor* _ref_processor_stw; 984 985 STWGCTimer* _gc_timer_stw; 986 ConcurrentGCTimer* _gc_timer_cm; 987 988 G1OldTracer* _gc_tracer_cm; 989 G1NewTracer* _gc_tracer_stw; 990 991 // During reference object discovery, the _is_alive_non_header 992 // closure (if non-null) is applied to the referent object to 993 // determine whether the referent is live. If so then the 994 // reference object does not need to be 'discovered' and can 995 // be treated as a regular oop. This has the benefit of reducing 996 // the number of 'discovered' reference objects that need to 997 // be processed. 998 // 999 // Instance of the is_alive closure for embedding into the 1000 // STW reference processor as the _is_alive_non_header field. 1001 // Supplying a value for the _is_alive_non_header field is 1002 // optional but doing so prevents unnecessary additions to 1003 // the discovered lists during reference discovery. 1004 G1STWIsAliveClosure _is_alive_closure_stw; 1005 1006 // The (concurrent marking) reference processor... 1007 ReferenceProcessor* _ref_processor_cm; 1008 1009 // Instance of the concurrent mark is_alive closure for embedding 1010 // into the Concurrent Marking reference processor as the 1011 // _is_alive_non_header field. Supplying a value for the 1012 // _is_alive_non_header field is optional but doing so prevents 1013 // unnecessary additions to the discovered lists during reference 1014 // discovery. 1015 G1CMIsAliveClosure _is_alive_closure_cm; 1016 1017 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1018 HeapRegion** _worker_cset_start_region; 1019 1020 // Time stamp to validate the regions recorded in the cache 1021 // used by G1CollectedHeap::start_cset_region_for_worker(). 1022 // The heap region entry for a given worker is valid iff 1023 // the associated time stamp value matches the current value 1024 // of G1CollectedHeap::_gc_time_stamp. 1025 uint* _worker_cset_start_region_time_stamp; 1026 1027 volatile bool _free_regions_coming; 1028 1029 public: 1030 1031 void set_refine_cte_cl_concurrency(bool concurrent); 1032 1033 RefToScanQueue *task_queue(uint i) const; 1034 1035 uint num_task_queues() const; 1036 1037 // A set of cards where updates happened during the GC 1038 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1039 1040 // A DirtyCardQueueSet that is used to hold cards that contain 1041 // references into the current collection set. This is used to 1042 // update the remembered sets of the regions in the collection 1043 // set in the event of an evacuation failure. 1044 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1045 { return _into_cset_dirty_card_queue_set; } 1046 1047 // Create a G1CollectedHeap with the specified policy. 1048 // Must call the initialize method afterwards. 1049 // May not return if something goes wrong. 1050 G1CollectedHeap(G1CollectorPolicy* policy); 1051 1052 // Initialize the G1CollectedHeap to have the initial and 1053 // maximum sizes and remembered and barrier sets 1054 // specified by the policy object. 1055 jint initialize(); 1056 1057 virtual void stop(); 1058 1059 // Return the (conservative) maximum heap alignment for any G1 heap 1060 static size_t conservative_max_heap_alignment(); 1061 1062 // Does operations required after initialization has been done. 1063 void post_initialize(); 1064 1065 // Initialize weak reference processing. 1066 void ref_processing_init(); 1067 1068 virtual Name kind() const { 1069 return CollectedHeap::G1CollectedHeap; 1070 } 1071 1072 G1CollectorState* collector_state() { return &_collector_state; } 1073 1074 // The current policy object for the collector. 1075 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1076 1077 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1078 1079 // Adaptive size policy. No such thing for g1. 1080 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1081 1082 // The rem set and barrier set. 1083 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1084 1085 unsigned get_gc_time_stamp() { 1086 return _gc_time_stamp; 1087 } 1088 1089 inline void reset_gc_time_stamp(); 1090 1091 void check_gc_time_stamps() PRODUCT_RETURN; 1092 1093 inline void increment_gc_time_stamp(); 1094 1095 // Reset the given region's GC timestamp. If it's starts humongous, 1096 // also reset the GC timestamp of its corresponding 1097 // continues humongous regions too. 1098 void reset_gc_time_stamps(HeapRegion* hr); 1099 1100 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1101 DirtyCardQueue* into_cset_dcq, 1102 bool concurrent, uint worker_i); 1103 1104 // The shared block offset table array. 1105 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1106 1107 // Reference Processing accessors 1108 1109 // The STW reference processor.... 1110 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1111 1112 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1113 1114 // The Concurrent Marking reference processor... 1115 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1116 1117 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1118 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1119 1120 virtual size_t capacity() const; 1121 virtual size_t used() const; 1122 // This should be called when we're not holding the heap lock. The 1123 // result might be a bit inaccurate. 1124 size_t used_unlocked() const; 1125 size_t recalculate_used() const; 1126 1127 // These virtual functions do the actual allocation. 1128 // Some heaps may offer a contiguous region for shared non-blocking 1129 // allocation, via inlined code (by exporting the address of the top and 1130 // end fields defining the extent of the contiguous allocation region.) 1131 // But G1CollectedHeap doesn't yet support this. 1132 1133 virtual bool is_maximal_no_gc() const { 1134 return _hrm.available() == 0; 1135 } 1136 1137 // The current number of regions in the heap. 1138 uint num_regions() const { return _hrm.length(); } 1139 1140 // The max number of regions in the heap. 1141 uint max_regions() const { return _hrm.max_length(); } 1142 1143 // The number of regions that are completely free. 1144 uint num_free_regions() const { return _hrm.num_free_regions(); } 1145 1146 MemoryUsage get_auxiliary_data_memory_usage() const { 1147 return _hrm.get_auxiliary_data_memory_usage(); 1148 } 1149 1150 // The number of regions that are not completely free. 1151 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1152 1153 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1154 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1155 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1156 void verify_dirty_young_regions() PRODUCT_RETURN; 1157 1158 #ifndef PRODUCT 1159 // Make sure that the given bitmap has no marked objects in the 1160 // range [from,limit). If it does, print an error message and return 1161 // false. Otherwise, just return true. bitmap_name should be "prev" 1162 // or "next". 1163 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1164 HeapWord* from, HeapWord* limit); 1165 1166 // Verify that the prev / next bitmap range [tams,end) for the given 1167 // region has no marks. Return true if all is well, false if errors 1168 // are detected. 1169 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1170 #endif // PRODUCT 1171 1172 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1173 // the given region do not have any spurious marks. If errors are 1174 // detected, print appropriate error messages and crash. 1175 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1176 1177 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1178 // have any spurious marks. If errors are detected, print 1179 // appropriate error messages and crash. 1180 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1181 1182 // Do sanity check on the contents of the in-cset fast test table. 1183 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1184 1185 // verify_region_sets() performs verification over the region 1186 // lists. It will be compiled in the product code to be used when 1187 // necessary (i.e., during heap verification). 1188 void verify_region_sets(); 1189 1190 // verify_region_sets_optional() is planted in the code for 1191 // list verification in non-product builds (and it can be enabled in 1192 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1193 #if HEAP_REGION_SET_FORCE_VERIFY 1194 void verify_region_sets_optional() { 1195 verify_region_sets(); 1196 } 1197 #else // HEAP_REGION_SET_FORCE_VERIFY 1198 void verify_region_sets_optional() { } 1199 #endif // HEAP_REGION_SET_FORCE_VERIFY 1200 1201 #ifdef ASSERT 1202 bool is_on_master_free_list(HeapRegion* hr) { 1203 return _hrm.is_free(hr); 1204 } 1205 #endif // ASSERT 1206 1207 // Wrapper for the region list operations that can be called from 1208 // methods outside this class. 1209 1210 void secondary_free_list_add(FreeRegionList* list) { 1211 _secondary_free_list.add_ordered(list); 1212 } 1213 1214 void append_secondary_free_list() { 1215 _hrm.insert_list_into_free_list(&_secondary_free_list); 1216 } 1217 1218 void append_secondary_free_list_if_not_empty_with_lock() { 1219 // If the secondary free list looks empty there's no reason to 1220 // take the lock and then try to append it. 1221 if (!_secondary_free_list.is_empty()) { 1222 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1223 append_secondary_free_list(); 1224 } 1225 } 1226 1227 inline void old_set_remove(HeapRegion* hr); 1228 1229 size_t non_young_capacity_bytes() { 1230 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1231 } 1232 1233 void set_free_regions_coming(); 1234 void reset_free_regions_coming(); 1235 bool free_regions_coming() { return _free_regions_coming; } 1236 void wait_while_free_regions_coming(); 1237 1238 // Determine whether the given region is one that we are using as an 1239 // old GC alloc region. 1240 bool is_old_gc_alloc_region(HeapRegion* hr) { 1241 return _allocator->is_retained_old_region(hr); 1242 } 1243 1244 // Perform a collection of the heap; intended for use in implementing 1245 // "System.gc". This probably implies as full a collection as the 1246 // "CollectedHeap" supports. 1247 virtual void collect(GCCause::Cause cause); 1248 1249 // The same as above but assume that the caller holds the Heap_lock. 1250 void collect_locked(GCCause::Cause cause); 1251 1252 virtual bool copy_allocation_context_stats(const jint* contexts, 1253 jlong* totals, 1254 jbyte* accuracy, 1255 jint len); 1256 1257 // True iff an evacuation has failed in the most-recent collection. 1258 bool evacuation_failed() { return _evacuation_failed; } 1259 1260 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1261 void prepend_to_freelist(FreeRegionList* list); 1262 void decrement_summary_bytes(size_t bytes); 1263 1264 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1265 virtual bool is_in(const void* p) const; 1266 #ifdef ASSERT 1267 // Returns whether p is in one of the available areas of the heap. Slow but 1268 // extensive version. 1269 bool is_in_exact(const void* p) const; 1270 #endif 1271 1272 // Return "TRUE" iff the given object address is within the collection 1273 // set. Slow implementation. 1274 inline bool obj_in_cs(oop obj); 1275 1276 inline bool is_in_cset(const HeapRegion *hr); 1277 inline bool is_in_cset(oop obj); 1278 1279 inline bool is_in_cset_or_humongous(const oop obj); 1280 1281 private: 1282 // This array is used for a quick test on whether a reference points into 1283 // the collection set or not. Each of the array's elements denotes whether the 1284 // corresponding region is in the collection set or not. 1285 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1286 1287 public: 1288 1289 inline InCSetState in_cset_state(const oop obj); 1290 1291 // Return "TRUE" iff the given object address is in the reserved 1292 // region of g1. 1293 bool is_in_g1_reserved(const void* p) const { 1294 return _hrm.reserved().contains(p); 1295 } 1296 1297 // Returns a MemRegion that corresponds to the space that has been 1298 // reserved for the heap 1299 MemRegion g1_reserved() const { 1300 return _hrm.reserved(); 1301 } 1302 1303 virtual bool is_in_closed_subset(const void* p) const; 1304 1305 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1306 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1307 } 1308 1309 // This resets the card table to all zeros. It is used after 1310 // a collection pause which used the card table to claim cards. 1311 void cleanUpCardTable(); 1312 1313 // Iteration functions. 1314 1315 // Iterate over all objects, calling "cl.do_object" on each. 1316 virtual void object_iterate(ObjectClosure* cl); 1317 1318 virtual void safe_object_iterate(ObjectClosure* cl) { 1319 object_iterate(cl); 1320 } 1321 1322 // Iterate over heap regions, in address order, terminating the 1323 // iteration early if the "doHeapRegion" method returns "true". 1324 void heap_region_iterate(HeapRegionClosure* blk) const; 1325 1326 // Return the region with the given index. It assumes the index is valid. 1327 inline HeapRegion* region_at(uint index) const; 1328 1329 // Calculate the region index of the given address. Given address must be 1330 // within the heap. 1331 inline uint addr_to_region(HeapWord* addr) const; 1332 1333 inline HeapWord* bottom_addr_for_region(uint index) const; 1334 1335 // Iterate over the heap regions in parallel. Assumes that this will be called 1336 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1337 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1338 // to each of the regions, by attempting to claim the region using the 1339 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1340 // region. The concurrent argument should be set to true if iteration is 1341 // performed concurrently, during which no assumptions are made for consistent 1342 // attributes of the heap regions (as they might be modified while iterating). 1343 void heap_region_par_iterate(HeapRegionClosure* cl, 1344 uint worker_id, 1345 HeapRegionClaimer* hrclaimer, 1346 bool concurrent = false) const; 1347 1348 // Clear the cached cset start regions and (more importantly) 1349 // the time stamps. Called when we reset the GC time stamp. 1350 void clear_cset_start_regions(); 1351 1352 // Given the id of a worker, obtain or calculate a suitable 1353 // starting region for iterating over the current collection set. 1354 HeapRegion* start_cset_region_for_worker(uint worker_i); 1355 1356 // Iterate over the regions (if any) in the current collection set. 1357 void collection_set_iterate(HeapRegionClosure* blk); 1358 1359 // As above but starting from region r 1360 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1361 1362 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1363 1364 // Returns the HeapRegion that contains addr. addr must not be NULL. 1365 template <class T> 1366 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1367 1368 // Returns the HeapRegion that contains addr. addr must not be NULL. 1369 // If addr is within a humongous continues region, it returns its humongous start region. 1370 template <class T> 1371 inline HeapRegion* heap_region_containing(const T addr) const; 1372 1373 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1374 // each address in the (reserved) heap is a member of exactly 1375 // one block. The defining characteristic of a block is that it is 1376 // possible to find its size, and thus to progress forward to the next 1377 // block. (Blocks may be of different sizes.) Thus, blocks may 1378 // represent Java objects, or they might be free blocks in a 1379 // free-list-based heap (or subheap), as long as the two kinds are 1380 // distinguishable and the size of each is determinable. 1381 1382 // Returns the address of the start of the "block" that contains the 1383 // address "addr". We say "blocks" instead of "object" since some heaps 1384 // may not pack objects densely; a chunk may either be an object or a 1385 // non-object. 1386 virtual HeapWord* block_start(const void* addr) const; 1387 1388 // Requires "addr" to be the start of a chunk, and returns its size. 1389 // "addr + size" is required to be the start of a new chunk, or the end 1390 // of the active area of the heap. 1391 virtual size_t block_size(const HeapWord* addr) const; 1392 1393 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1394 // the block is an object. 1395 virtual bool block_is_obj(const HeapWord* addr) const; 1396 1397 // Section on thread-local allocation buffers (TLABs) 1398 // See CollectedHeap for semantics. 1399 1400 bool supports_tlab_allocation() const; 1401 size_t tlab_capacity(Thread* ignored) const; 1402 size_t tlab_used(Thread* ignored) const; 1403 size_t max_tlab_size() const; 1404 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1405 1406 // Can a compiler initialize a new object without store barriers? 1407 // This permission only extends from the creation of a new object 1408 // via a TLAB up to the first subsequent safepoint. If such permission 1409 // is granted for this heap type, the compiler promises to call 1410 // defer_store_barrier() below on any slow path allocation of 1411 // a new object for which such initializing store barriers will 1412 // have been elided. G1, like CMS, allows this, but should be 1413 // ready to provide a compensating write barrier as necessary 1414 // if that storage came out of a non-young region. The efficiency 1415 // of this implementation depends crucially on being able to 1416 // answer very efficiently in constant time whether a piece of 1417 // storage in the heap comes from a young region or not. 1418 // See ReduceInitialCardMarks. 1419 virtual bool can_elide_tlab_store_barriers() const { 1420 return true; 1421 } 1422 1423 virtual bool card_mark_must_follow_store() const { 1424 return true; 1425 } 1426 1427 inline bool is_in_young(const oop obj); 1428 1429 virtual bool is_scavengable(const void* addr); 1430 1431 // We don't need barriers for initializing stores to objects 1432 // in the young gen: for the SATB pre-barrier, there is no 1433 // pre-value that needs to be remembered; for the remembered-set 1434 // update logging post-barrier, we don't maintain remembered set 1435 // information for young gen objects. 1436 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1437 1438 // Returns "true" iff the given word_size is "very large". 1439 static bool is_humongous(size_t word_size) { 1440 // Note this has to be strictly greater-than as the TLABs 1441 // are capped at the humongous threshold and we want to 1442 // ensure that we don't try to allocate a TLAB as 1443 // humongous and that we don't allocate a humongous 1444 // object in a TLAB. 1445 return word_size > _humongous_object_threshold_in_words; 1446 } 1447 1448 // Returns the humongous threshold for a specific region size 1449 static size_t humongous_threshold_for(size_t region_size) { 1450 return (region_size / 2); 1451 } 1452 1453 // Update mod union table with the set of dirty cards. 1454 void updateModUnion(); 1455 1456 // Set the mod union bits corresponding to the given memRegion. Note 1457 // that this is always a safe operation, since it doesn't clear any 1458 // bits. 1459 void markModUnionRange(MemRegion mr); 1460 1461 // Print the maximum heap capacity. 1462 virtual size_t max_capacity() const; 1463 1464 virtual jlong millis_since_last_gc(); 1465 1466 1467 // Convenience function to be used in situations where the heap type can be 1468 // asserted to be this type. 1469 static G1CollectedHeap* heap(); 1470 1471 void set_region_short_lived_locked(HeapRegion* hr); 1472 // add appropriate methods for any other surv rate groups 1473 1474 YoungList* young_list() const { return _young_list; } 1475 1476 // debugging 1477 bool check_young_list_well_formed() { 1478 return _young_list->check_list_well_formed(); 1479 } 1480 1481 bool check_young_list_empty(bool check_heap, 1482 bool check_sample = true); 1483 1484 // *** Stuff related to concurrent marking. It's not clear to me that so 1485 // many of these need to be public. 1486 1487 // The functions below are helper functions that a subclass of 1488 // "CollectedHeap" can use in the implementation of its virtual 1489 // functions. 1490 // This performs a concurrent marking of the live objects in a 1491 // bitmap off to the side. 1492 void doConcurrentMark(); 1493 1494 bool isMarkedPrev(oop obj) const; 1495 bool isMarkedNext(oop obj) const; 1496 1497 // Determine if an object is dead, given the object and also 1498 // the region to which the object belongs. An object is dead 1499 // iff a) it was not allocated since the last mark, b) it 1500 // is not marked, and c) it is not in an archive region. 1501 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1502 return 1503 !hr->obj_allocated_since_prev_marking(obj) && 1504 !isMarkedPrev(obj) && 1505 !hr->is_archive(); 1506 } 1507 1508 // This function returns true when an object has been 1509 // around since the previous marking and hasn't yet 1510 // been marked during this marking, and is not in an archive region. 1511 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1512 return 1513 !hr->obj_allocated_since_next_marking(obj) && 1514 !isMarkedNext(obj) && 1515 !hr->is_archive(); 1516 } 1517 1518 // Determine if an object is dead, given only the object itself. 1519 // This will find the region to which the object belongs and 1520 // then call the region version of the same function. 1521 1522 // Added if it is NULL it isn't dead. 1523 1524 inline bool is_obj_dead(const oop obj) const; 1525 1526 inline bool is_obj_ill(const oop obj) const; 1527 1528 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1529 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1530 bool is_marked(oop obj, VerifyOption vo); 1531 const char* top_at_mark_start_str(VerifyOption vo); 1532 1533 ConcurrentMark* concurrent_mark() const { return _cm; } 1534 1535 // Refinement 1536 1537 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1538 1539 // The dirty cards region list is used to record a subset of regions 1540 // whose cards need clearing. The list if populated during the 1541 // remembered set scanning and drained during the card table 1542 // cleanup. Although the methods are reentrant, population/draining 1543 // phases must not overlap. For synchronization purposes the last 1544 // element on the list points to itself. 1545 HeapRegion* _dirty_cards_region_list; 1546 void push_dirty_cards_region(HeapRegion* hr); 1547 HeapRegion* pop_dirty_cards_region(); 1548 1549 // Optimized nmethod scanning support routines 1550 1551 // Register the given nmethod with the G1 heap. 1552 virtual void register_nmethod(nmethod* nm); 1553 1554 // Unregister the given nmethod from the G1 heap. 1555 virtual void unregister_nmethod(nmethod* nm); 1556 1557 // Free up superfluous code root memory. 1558 void purge_code_root_memory(); 1559 1560 // Rebuild the strong code root lists for each region 1561 // after a full GC. 1562 void rebuild_strong_code_roots(); 1563 1564 // Delete entries for dead interned string and clean up unreferenced symbols 1565 // in symbol table, possibly in parallel. 1566 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1567 1568 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1569 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1570 1571 // Redirty logged cards in the refinement queue. 1572 void redirty_logged_cards(); 1573 // Verification 1574 1575 // Perform any cleanup actions necessary before allowing a verification. 1576 virtual void prepare_for_verify(); 1577 1578 // Perform verification. 1579 1580 // vo == UsePrevMarking -> use "prev" marking information, 1581 // vo == UseNextMarking -> use "next" marking information 1582 // vo == UseMarkWord -> use the mark word in the object header 1583 // 1584 // NOTE: Only the "prev" marking information is guaranteed to be 1585 // consistent most of the time, so most calls to this should use 1586 // vo == UsePrevMarking. 1587 // Currently, there is only one case where this is called with 1588 // vo == UseNextMarking, which is to verify the "next" marking 1589 // information at the end of remark. 1590 // Currently there is only one place where this is called with 1591 // vo == UseMarkWord, which is to verify the marking during a 1592 // full GC. 1593 void verify(bool silent, VerifyOption vo); 1594 1595 // Override; it uses the "prev" marking information 1596 virtual void verify(bool silent); 1597 1598 // The methods below are here for convenience and dispatch the 1599 // appropriate method depending on value of the given VerifyOption 1600 // parameter. The values for that parameter, and their meanings, 1601 // are the same as those above. 1602 1603 bool is_obj_dead_cond(const oop obj, 1604 const HeapRegion* hr, 1605 const VerifyOption vo) const; 1606 1607 bool is_obj_dead_cond(const oop obj, 1608 const VerifyOption vo) const; 1609 1610 G1HeapSummary create_g1_heap_summary(); 1611 1612 // Printing 1613 1614 virtual void print_on(outputStream* st) const; 1615 virtual void print_extended_on(outputStream* st) const; 1616 virtual void print_on_error(outputStream* st) const; 1617 1618 virtual void print_gc_threads_on(outputStream* st) const; 1619 virtual void gc_threads_do(ThreadClosure* tc) const; 1620 1621 // Override 1622 void print_tracing_info() const; 1623 1624 // The following two methods are helpful for debugging RSet issues. 1625 void print_cset_rsets() PRODUCT_RETURN; 1626 void print_all_rsets() PRODUCT_RETURN; 1627 1628 public: 1629 size_t pending_card_num(); 1630 size_t cards_scanned(); 1631 1632 protected: 1633 size_t _max_heap_capacity; 1634 }; 1635 1636 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP