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/g1HRPrinter.hpp" 35 #include "gc/g1/g1InCSetState.hpp" 36 #include "gc/g1/g1MonitoringSupport.hpp" 37 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 38 #include "gc/g1/g1YCTypes.hpp" 39 #include "gc/g1/hSpaceCounters.hpp" 40 #include "gc/g1/heapRegionManager.hpp" 41 #include "gc/g1/heapRegionSet.hpp" 42 #include "gc/shared/barrierSet.hpp" 43 #include "gc/shared/collectedHeap.hpp" 44 #include "memory/memRegion.hpp" 45 #include "utilities/stack.hpp" 46 47 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 48 // It uses the "Garbage First" heap organization and algorithm, which 49 // may combine concurrent marking with parallel, incremental compaction of 50 // heap subsets that will yield large amounts of garbage. 51 52 // Forward declarations 53 class HeapRegion; 54 class HRRSCleanupTask; 55 class GenerationSpec; 56 class OopsInHeapRegionClosure; 57 class G1KlassScanClosure; 58 class G1ParScanThreadState; 59 class ObjectClosure; 60 class SpaceClosure; 61 class CompactibleSpaceClosure; 62 class Space; 63 class G1CollectorPolicy; 64 class GenRemSet; 65 class G1RemSet; 66 class HeapRegionRemSetIterator; 67 class ConcurrentMark; 68 class ConcurrentMarkThread; 69 class ConcurrentG1Refine; 70 class ConcurrentGCTimer; 71 class GenerationCounters; 72 class STWGCTimer; 73 class G1NewTracer; 74 class G1OldTracer; 75 class EvacuationFailedInfo; 76 class nmethod; 77 class Ticks; 78 class FlexibleWorkGang; 79 80 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 81 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 82 83 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 84 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 85 86 class YoungList : public CHeapObj<mtGC> { 87 private: 88 G1CollectedHeap* _g1h; 89 90 HeapRegion* _head; 91 92 HeapRegion* _survivor_head; 93 HeapRegion* _survivor_tail; 94 95 HeapRegion* _curr; 96 97 uint _length; 98 uint _survivor_length; 99 100 size_t _last_sampled_rs_lengths; 101 size_t _sampled_rs_lengths; 102 103 void empty_list(HeapRegion* list); 104 105 public: 106 YoungList(G1CollectedHeap* g1h); 107 108 void push_region(HeapRegion* hr); 109 void add_survivor_region(HeapRegion* hr); 110 111 void empty_list(); 112 bool is_empty() { return _length == 0; } 113 uint length() { return _length; } 114 uint eden_length() { return length() - survivor_length(); } 115 uint survivor_length() { return _survivor_length; } 116 117 // Currently we do not keep track of the used byte sum for the 118 // young list and the survivors and it'd be quite a lot of work to 119 // do so. When we'll eventually replace the young list with 120 // instances of HeapRegionLinkedList we'll get that for free. So, 121 // we'll report the more accurate information then. 122 size_t eden_used_bytes() { 123 assert(length() >= survivor_length(), "invariant"); 124 return (size_t) eden_length() * HeapRegion::GrainBytes; 125 } 126 size_t survivor_used_bytes() { 127 return (size_t) survivor_length() * HeapRegion::GrainBytes; 128 } 129 130 void rs_length_sampling_init(); 131 bool rs_length_sampling_more(); 132 void rs_length_sampling_next(); 133 134 void reset_sampled_info() { 135 _last_sampled_rs_lengths = 0; 136 } 137 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 138 139 // for development purposes 140 void reset_auxilary_lists(); 141 void clear() { _head = NULL; _length = 0; } 142 143 void clear_survivors() { 144 _survivor_head = NULL; 145 _survivor_tail = NULL; 146 _survivor_length = 0; 147 } 148 149 HeapRegion* first_region() { return _head; } 150 HeapRegion* first_survivor_region() { return _survivor_head; } 151 HeapRegion* last_survivor_region() { return _survivor_tail; } 152 153 // debugging 154 bool check_list_well_formed(); 155 bool check_list_empty(bool check_sample = true); 156 void print(); 157 }; 158 159 // The G1 STW is alive closure. 160 // An instance is embedded into the G1CH and used as the 161 // (optional) _is_alive_non_header closure in the STW 162 // reference processor. It is also extensively used during 163 // reference processing during STW evacuation pauses. 164 class G1STWIsAliveClosure: public BoolObjectClosure { 165 G1CollectedHeap* _g1; 166 public: 167 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 168 bool do_object_b(oop p); 169 }; 170 171 class RefineCardTableEntryClosure; 172 173 class G1RegionMappingChangedListener : public G1MappingChangedListener { 174 private: 175 void reset_from_card_cache(uint start_idx, size_t num_regions); 176 public: 177 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 178 }; 179 180 class G1CollectedHeap : public CollectedHeap { 181 friend class VM_CollectForMetadataAllocation; 182 friend class VM_G1CollectForAllocation; 183 friend class VM_G1CollectFull; 184 friend class VM_G1IncCollectionPause; 185 friend class VMStructs; 186 friend class MutatorAllocRegion; 187 friend class SurvivorGCAllocRegion; 188 friend class OldGCAllocRegion; 189 friend class G1Allocator; 190 191 // Closures used in implementation. 192 friend class G1ParScanThreadState; 193 friend class G1ParTask; 194 friend class G1ParGCAllocator; 195 friend class G1PrepareCompactClosure; 196 197 // Other related classes. 198 friend class HeapRegionClaimer; 199 200 // Testing classes. 201 friend class G1CheckCSetFastTableClosure; 202 203 private: 204 FlexibleWorkGang* _workers; 205 206 static size_t _humongous_object_threshold_in_words; 207 208 // The secondary free list which contains regions that have been 209 // freed up during the cleanup process. This will be appended to 210 // the master free list when appropriate. 211 FreeRegionList _secondary_free_list; 212 213 // It keeps track of the old regions. 214 HeapRegionSet _old_set; 215 216 // It keeps track of the humongous regions. 217 HeapRegionSet _humongous_set; 218 219 void eagerly_reclaim_humongous_regions(); 220 221 // The number of regions we could create by expansion. 222 uint _expansion_regions; 223 224 // The block offset table for the G1 heap. 225 G1BlockOffsetSharedArray* _bot_shared; 226 227 // Tears down the region sets / lists so that they are empty and the 228 // regions on the heap do not belong to a region set / list. The 229 // only exception is the humongous set which we leave unaltered. If 230 // free_list_only is true, it will only tear down the master free 231 // list. It is called before a Full GC (free_list_only == false) or 232 // before heap shrinking (free_list_only == true). 233 void tear_down_region_sets(bool free_list_only); 234 235 // Rebuilds the region sets / lists so that they are repopulated to 236 // reflect the contents of the heap. The only exception is the 237 // humongous set which was not torn down in the first place. If 238 // free_list_only is true, it will only rebuild the master free 239 // list. It is called after a Full GC (free_list_only == false) or 240 // after heap shrinking (free_list_only == true). 241 void rebuild_region_sets(bool free_list_only); 242 243 // Callback for region mapping changed events. 244 G1RegionMappingChangedListener _listener; 245 246 // The sequence of all heap regions in the heap. 247 HeapRegionManager _hrm; 248 249 // Class that handles the different kinds of allocations. 250 G1Allocator* _allocator; 251 252 // Statistics for each allocation context 253 AllocationContextStats _allocation_context_stats; 254 255 // PLAB sizing policy for survivors. 256 PLABStats _survivor_plab_stats; 257 258 // PLAB sizing policy for tenured objects. 259 PLABStats _old_plab_stats; 260 261 // It specifies whether we should attempt to expand the heap after a 262 // region allocation failure. If heap expansion fails we set this to 263 // false so that we don't re-attempt the heap expansion (it's likely 264 // that subsequent expansion attempts will also fail if one fails). 265 // Currently, it is only consulted during GC and it's reset at the 266 // start of each GC. 267 bool _expand_heap_after_alloc_failure; 268 269 // It resets the mutator alloc region before new allocations can take place. 270 void init_mutator_alloc_region(); 271 272 // It releases the mutator alloc region. 273 void release_mutator_alloc_region(); 274 275 // It initializes the GC alloc regions at the start of a GC. 276 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 277 278 // It releases the GC alloc regions at the end of a GC. 279 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 280 281 // It does any cleanup that needs to be done on the GC alloc regions 282 // before a Full GC. 283 void abandon_gc_alloc_regions(); 284 285 // Helper for monitoring and management support. 286 G1MonitoringSupport* _g1mm; 287 288 // Records whether the region at the given index is (still) a 289 // candidate for eager reclaim. Only valid for humongous start 290 // regions; other regions have unspecified values. Humongous start 291 // regions are initialized at start of collection pause, with 292 // candidates removed from the set as they are found reachable from 293 // roots or the young generation. 294 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 295 protected: 296 bool default_value() const { return false; } 297 public: 298 void clear() { G1BiasedMappedArray<bool>::clear(); } 299 void set_candidate(uint region, bool value) { 300 set_by_index(region, value); 301 } 302 bool is_candidate(uint region) { 303 return get_by_index(region); 304 } 305 }; 306 307 HumongousReclaimCandidates _humongous_reclaim_candidates; 308 // Stores whether during humongous object registration we found candidate regions. 309 // If not, we can skip a few steps. 310 bool _has_humongous_reclaim_candidates; 311 312 volatile unsigned _gc_time_stamp; 313 314 size_t* _surviving_young_words; 315 316 G1HRPrinter _hr_printer; 317 318 void setup_surviving_young_words(); 319 void update_surviving_young_words(size_t* surv_young_words); 320 void cleanup_surviving_young_words(); 321 322 // It decides whether an explicit GC should start a concurrent cycle 323 // instead of doing a STW GC. Currently, a concurrent cycle is 324 // explicitly started if: 325 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 326 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 327 // (c) cause == _g1_humongous_allocation 328 bool should_do_concurrent_full_gc(GCCause::Cause cause); 329 330 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 331 // concurrent cycles) we have started. 332 volatile uint _old_marking_cycles_started; 333 334 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 335 // concurrent cycles) we have completed. 336 volatile uint _old_marking_cycles_completed; 337 338 bool _concurrent_cycle_started; 339 bool _heap_summary_sent; 340 341 // This is a non-product method that is helpful for testing. It is 342 // called at the end of a GC and artificially expands the heap by 343 // allocating a number of dead regions. This way we can induce very 344 // frequent marking cycles and stress the cleanup / concurrent 345 // cleanup code more (as all the regions that will be allocated by 346 // this method will be found dead by the marking cycle). 347 void allocate_dummy_regions() PRODUCT_RETURN; 348 349 // Clear RSets after a compaction. It also resets the GC time stamps. 350 void clear_rsets_post_compaction(); 351 352 // If the HR printer is active, dump the state of the regions in the 353 // heap after a compaction. 354 void print_hrm_post_compaction(); 355 356 // Create a memory mapper for auxiliary data structures of the given size and 357 // translation factor. 358 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 359 size_t size, 360 size_t translation_factor); 361 362 double verify(bool guard, const char* msg); 363 void verify_before_gc(); 364 void verify_after_gc(); 365 366 void log_gc_header(); 367 void log_gc_footer(double pause_time_sec); 368 369 // These are macros so that, if the assert fires, we get the correct 370 // line number, file, etc. 371 372 #define heap_locking_asserts_err_msg(_extra_message_) \ 373 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 374 (_extra_message_), \ 375 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 376 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 377 BOOL_TO_STR(Thread::current()->is_VM_thread())) 378 379 #define assert_heap_locked() \ 380 do { \ 381 assert(Heap_lock->owned_by_self(), \ 382 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 383 } while (0) 384 385 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 386 do { \ 387 assert(Heap_lock->owned_by_self() || \ 388 (SafepointSynchronize::is_at_safepoint() && \ 389 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 390 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 391 "should be at a safepoint")); \ 392 } while (0) 393 394 #define assert_heap_locked_and_not_at_safepoint() \ 395 do { \ 396 assert(Heap_lock->owned_by_self() && \ 397 !SafepointSynchronize::is_at_safepoint(), \ 398 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 399 "should not be at a safepoint")); \ 400 } while (0) 401 402 #define assert_heap_not_locked() \ 403 do { \ 404 assert(!Heap_lock->owned_by_self(), \ 405 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 406 } while (0) 407 408 #define assert_heap_not_locked_and_not_at_safepoint() \ 409 do { \ 410 assert(!Heap_lock->owned_by_self() && \ 411 !SafepointSynchronize::is_at_safepoint(), \ 412 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 413 "should not be at a safepoint")); \ 414 } while (0) 415 416 #define assert_at_safepoint(_should_be_vm_thread_) \ 417 do { \ 418 assert(SafepointSynchronize::is_at_safepoint() && \ 419 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 420 heap_locking_asserts_err_msg("should be at a safepoint")); \ 421 } while (0) 422 423 #define assert_not_at_safepoint() \ 424 do { \ 425 assert(!SafepointSynchronize::is_at_safepoint(), \ 426 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 427 } while (0) 428 429 protected: 430 431 // The young region list. 432 YoungList* _young_list; 433 434 // The current policy object for the collector. 435 G1CollectorPolicy* _g1_policy; 436 437 // This is the second level of trying to allocate a new region. If 438 // new_region() didn't find a region on the free_list, this call will 439 // check whether there's anything available on the 440 // secondary_free_list and/or wait for more regions to appear on 441 // that list, if _free_regions_coming is set. 442 HeapRegion* new_region_try_secondary_free_list(bool is_old); 443 444 // Try to allocate a single non-humongous HeapRegion sufficient for 445 // an allocation of the given word_size. If do_expand is true, 446 // attempt to expand the heap if necessary to satisfy the allocation 447 // request. If the region is to be used as an old region or for a 448 // humongous object, set is_old to true. If not, to false. 449 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 450 451 // Initialize a contiguous set of free regions of length num_regions 452 // and starting at index first so that they appear as a single 453 // humongous region. 454 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 455 uint num_regions, 456 size_t word_size, 457 AllocationContext_t context); 458 459 // Attempt to allocate a humongous object of the given size. Return 460 // NULL if unsuccessful. 461 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 462 463 // The following two methods, allocate_new_tlab() and 464 // mem_allocate(), are the two main entry points from the runtime 465 // into the G1's allocation routines. They have the following 466 // assumptions: 467 // 468 // * They should both be called outside safepoints. 469 // 470 // * They should both be called without holding the Heap_lock. 471 // 472 // * All allocation requests for new TLABs should go to 473 // allocate_new_tlab(). 474 // 475 // * All non-TLAB allocation requests should go to mem_allocate(). 476 // 477 // * If either call cannot satisfy the allocation request using the 478 // current allocating region, they will try to get a new one. If 479 // this fails, they will attempt to do an evacuation pause and 480 // retry the allocation. 481 // 482 // * If all allocation attempts fail, even after trying to schedule 483 // an evacuation pause, allocate_new_tlab() will return NULL, 484 // whereas mem_allocate() will attempt a heap expansion and/or 485 // schedule a Full GC. 486 // 487 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 488 // should never be called with word_size being humongous. All 489 // humongous allocation requests should go to mem_allocate() which 490 // will satisfy them with a special path. 491 492 virtual HeapWord* allocate_new_tlab(size_t word_size); 493 494 virtual HeapWord* mem_allocate(size_t word_size, 495 bool* gc_overhead_limit_was_exceeded); 496 497 // The following three methods take a gc_count_before_ret 498 // parameter which is used to return the GC count if the method 499 // returns NULL. Given that we are required to read the GC count 500 // while holding the Heap_lock, and these paths will take the 501 // Heap_lock at some point, it's easier to get them to read the GC 502 // count while holding the Heap_lock before they return NULL instead 503 // of the caller (namely: mem_allocate()) having to also take the 504 // Heap_lock just to read the GC count. 505 506 // First-level mutator allocation attempt: try to allocate out of 507 // the mutator alloc region without taking the Heap_lock. This 508 // should only be used for non-humongous allocations. 509 inline HeapWord* attempt_allocation(size_t word_size, 510 uint* gc_count_before_ret, 511 uint* gclocker_retry_count_ret); 512 513 // Second-level mutator allocation attempt: take the Heap_lock and 514 // retry the allocation attempt, potentially scheduling a GC 515 // pause. This should only be used for non-humongous allocations. 516 HeapWord* attempt_allocation_slow(size_t word_size, 517 AllocationContext_t context, 518 uint* gc_count_before_ret, 519 uint* gclocker_retry_count_ret); 520 521 // Takes the Heap_lock and attempts a humongous allocation. It can 522 // potentially schedule a GC pause. 523 HeapWord* attempt_allocation_humongous(size_t word_size, 524 uint* gc_count_before_ret, 525 uint* gclocker_retry_count_ret); 526 527 // Allocation attempt that should be called during safepoints (e.g., 528 // at the end of a successful GC). expect_null_mutator_alloc_region 529 // specifies whether the mutator alloc region is expected to be NULL 530 // or not. 531 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 532 AllocationContext_t context, 533 bool expect_null_mutator_alloc_region); 534 535 // It dirties the cards that cover the block so that so that the post 536 // write barrier never queues anything when updating objects on this 537 // block. It is assumed (and in fact we assert) that the block 538 // belongs to a young region. 539 inline void dirty_young_block(HeapWord* start, size_t word_size); 540 541 // Allocate blocks during garbage collection. Will ensure an 542 // allocation region, either by picking one or expanding the 543 // heap, and then allocate a block of the given size. The block 544 // may not be a humongous - it must fit into a single heap region. 545 inline HeapWord* par_allocate_during_gc(InCSetState dest, 546 size_t word_size, 547 AllocationContext_t context); 548 // Ensure that no further allocations can happen in "r", bearing in mind 549 // that parallel threads might be attempting allocations. 550 void par_allocate_remaining_space(HeapRegion* r); 551 552 // Allocation attempt during GC for a survivor object / PLAB. 553 inline HeapWord* survivor_attempt_allocation(size_t word_size, 554 AllocationContext_t context); 555 556 // Allocation attempt during GC for an old object / PLAB. 557 inline HeapWord* old_attempt_allocation(size_t word_size, 558 AllocationContext_t context); 559 560 // These methods are the "callbacks" from the G1AllocRegion class. 561 562 // For mutator alloc regions. 563 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 564 void retire_mutator_alloc_region(HeapRegion* alloc_region, 565 size_t allocated_bytes); 566 567 // For GC alloc regions. 568 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 569 InCSetState dest); 570 void retire_gc_alloc_region(HeapRegion* alloc_region, 571 size_t allocated_bytes, InCSetState dest); 572 573 // - if explicit_gc is true, the GC is for a System.gc() or a heap 574 // inspection request and should collect the entire heap 575 // - if clear_all_soft_refs is true, all soft references should be 576 // cleared during the GC 577 // - if explicit_gc is false, word_size describes the allocation that 578 // the GC should attempt (at least) to satisfy 579 // - it returns false if it is unable to do the collection due to the 580 // GC locker being active, true otherwise 581 bool do_collection(bool explicit_gc, 582 bool clear_all_soft_refs, 583 size_t word_size); 584 585 // Callback from VM_G1CollectFull operation. 586 // Perform a full collection. 587 virtual void do_full_collection(bool clear_all_soft_refs); 588 589 // Resize the heap if necessary after a full collection. If this is 590 // after a collect-for allocation, "word_size" is the allocation size, 591 // and will be considered part of the used portion of the heap. 592 void resize_if_necessary_after_full_collection(size_t word_size); 593 594 // Callback from VM_G1CollectForAllocation operation. 595 // This function does everything necessary/possible to satisfy a 596 // failed allocation request (including collection, expansion, etc.) 597 HeapWord* satisfy_failed_allocation(size_t word_size, 598 AllocationContext_t context, 599 bool* succeeded); 600 601 // Attempting to expand the heap sufficiently 602 // to support an allocation of the given "word_size". If 603 // successful, perform the allocation and return the address of the 604 // allocated block, or else "NULL". 605 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 606 607 // Process any reference objects discovered during 608 // an incremental evacuation pause. 609 void process_discovered_references(uint no_of_gc_workers); 610 611 // Enqueue any remaining discovered references 612 // after processing. 613 void enqueue_discovered_references(uint no_of_gc_workers); 614 615 public: 616 FlexibleWorkGang* workers() const { return _workers; } 617 618 G1Allocator* allocator() { 619 return _allocator; 620 } 621 622 G1MonitoringSupport* g1mm() { 623 assert(_g1mm != NULL, "should have been initialized"); 624 return _g1mm; 625 } 626 627 // Expand the garbage-first heap by at least the given size (in bytes!). 628 // Returns true if the heap was expanded by the requested amount; 629 // false otherwise. 630 // (Rounds up to a HeapRegion boundary.) 631 bool expand(size_t expand_bytes); 632 633 // Returns the PLAB statistics for a given destination. 634 inline PLABStats* alloc_buffer_stats(InCSetState dest); 635 636 // Determines PLAB size for a given destination. 637 inline size_t desired_plab_sz(InCSetState dest); 638 639 inline AllocationContextStats& allocation_context_stats(); 640 641 // Do anything common to GC's. 642 void gc_prologue(bool full); 643 void gc_epilogue(bool full); 644 645 // Modify the reclaim candidate set and test for presence. 646 // These are only valid for starts_humongous regions. 647 inline void set_humongous_reclaim_candidate(uint region, bool value); 648 inline bool is_humongous_reclaim_candidate(uint region); 649 650 // Remove from the reclaim candidate set. Also remove from the 651 // collection set so that later encounters avoid the slow path. 652 inline void set_humongous_is_live(oop obj); 653 654 // Register the given region to be part of the collection set. 655 inline void register_humongous_region_with_cset(uint index); 656 // Register regions with humongous objects (actually on the start region) in 657 // the in_cset_fast_test table. 658 void register_humongous_regions_with_cset(); 659 // We register a region with the fast "in collection set" test. We 660 // simply set to true the array slot corresponding to this region. 661 void register_young_region_with_cset(HeapRegion* r) { 662 _in_cset_fast_test.set_in_young(r->hrm_index()); 663 } 664 void register_old_region_with_cset(HeapRegion* r) { 665 _in_cset_fast_test.set_in_old(r->hrm_index()); 666 } 667 void clear_in_cset(const HeapRegion* hr) { 668 _in_cset_fast_test.clear(hr); 669 } 670 671 void clear_cset_fast_test() { 672 _in_cset_fast_test.clear(); 673 } 674 675 // This is called at the start of either a concurrent cycle or a Full 676 // GC to update the number of old marking cycles started. 677 void increment_old_marking_cycles_started(); 678 679 // This is called at the end of either a concurrent cycle or a Full 680 // GC to update the number of old marking cycles completed. Those two 681 // can happen in a nested fashion, i.e., we start a concurrent 682 // cycle, a Full GC happens half-way through it which ends first, 683 // and then the cycle notices that a Full GC happened and ends 684 // too. The concurrent parameter is a boolean to help us do a bit 685 // tighter consistency checking in the method. If concurrent is 686 // false, the caller is the inner caller in the nesting (i.e., the 687 // Full GC). If concurrent is true, the caller is the outer caller 688 // in this nesting (i.e., the concurrent cycle). Further nesting is 689 // not currently supported. The end of this call also notifies 690 // the FullGCCount_lock in case a Java thread is waiting for a full 691 // GC to happen (e.g., it called System.gc() with 692 // +ExplicitGCInvokesConcurrent). 693 void increment_old_marking_cycles_completed(bool concurrent); 694 695 uint old_marking_cycles_completed() { 696 return _old_marking_cycles_completed; 697 } 698 699 void register_concurrent_cycle_start(const Ticks& start_time); 700 void register_concurrent_cycle_end(); 701 void trace_heap_after_concurrent_cycle(); 702 703 G1YCType yc_type(); 704 705 G1HRPrinter* hr_printer() { return &_hr_printer; } 706 707 // Frees a non-humongous region by initializing its contents and 708 // adding it to the free list that's passed as a parameter (this is 709 // usually a local list which will be appended to the master free 710 // list later). The used bytes of freed regions are accumulated in 711 // pre_used. If par is true, the region's RSet will not be freed 712 // up. The assumption is that this will be done later. 713 // The locked parameter indicates if the caller has already taken 714 // care of proper synchronization. This may allow some optimizations. 715 void free_region(HeapRegion* hr, 716 FreeRegionList* free_list, 717 bool par, 718 bool locked = false); 719 720 // Frees a humongous region by collapsing it into individual regions 721 // and calling free_region() for each of them. The freed regions 722 // will be added to the free list that's passed as a parameter (this 723 // is usually a local list which will be appended to the master free 724 // list later). The used bytes of freed regions are accumulated in 725 // pre_used. If par is true, the region's RSet will not be freed 726 // up. The assumption is that this will be done later. 727 void free_humongous_region(HeapRegion* hr, 728 FreeRegionList* free_list, 729 bool par); 730 protected: 731 732 // Shrink the garbage-first heap by at most the given size (in bytes!). 733 // (Rounds down to a HeapRegion boundary.) 734 virtual void shrink(size_t expand_bytes); 735 void shrink_helper(size_t expand_bytes); 736 737 #if TASKQUEUE_STATS 738 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 739 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 740 void reset_taskqueue_stats(); 741 #endif // TASKQUEUE_STATS 742 743 // Schedule the VM operation that will do an evacuation pause to 744 // satisfy an allocation request of word_size. *succeeded will 745 // return whether the VM operation was successful (it did do an 746 // evacuation pause) or not (another thread beat us to it or the GC 747 // locker was active). Given that we should not be holding the 748 // Heap_lock when we enter this method, we will pass the 749 // gc_count_before (i.e., total_collections()) as a parameter since 750 // it has to be read while holding the Heap_lock. Currently, both 751 // methods that call do_collection_pause() release the Heap_lock 752 // before the call, so it's easy to read gc_count_before just before. 753 HeapWord* do_collection_pause(size_t word_size, 754 uint gc_count_before, 755 bool* succeeded, 756 GCCause::Cause gc_cause); 757 758 // The guts of the incremental collection pause, executed by the vm 759 // thread. It returns false if it is unable to do the collection due 760 // to the GC locker being active, true otherwise 761 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 762 763 // Actually do the work of evacuating the collection set. 764 void evacuate_collection_set(EvacuationInfo& evacuation_info); 765 766 // The g1 remembered set of the heap. 767 G1RemSet* _g1_rem_set; 768 769 // A set of cards that cover the objects for which the Rsets should be updated 770 // concurrently after the collection. 771 DirtyCardQueueSet _dirty_card_queue_set; 772 773 // The closure used to refine a single card. 774 RefineCardTableEntryClosure* _refine_cte_cl; 775 776 // A DirtyCardQueueSet that is used to hold cards that contain 777 // references into the current collection set. This is used to 778 // update the remembered sets of the regions in the collection 779 // set in the event of an evacuation failure. 780 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 781 782 // After a collection pause, make the regions in the CS into free 783 // regions. 784 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 785 786 // Abandon the current collection set without recording policy 787 // statistics or updating free lists. 788 void abandon_collection_set(HeapRegion* cs_head); 789 790 // The concurrent marker (and the thread it runs in.) 791 ConcurrentMark* _cm; 792 ConcurrentMarkThread* _cmThread; 793 bool _mark_in_progress; 794 795 // The concurrent refiner. 796 ConcurrentG1Refine* _cg1r; 797 798 // The parallel task queues 799 RefToScanQueueSet *_task_queues; 800 801 // True iff a evacuation has failed in the current collection. 802 bool _evacuation_failed; 803 804 EvacuationFailedInfo* _evacuation_failed_info_array; 805 806 // Failed evacuations cause some logical from-space objects to have 807 // forwarding pointers to themselves. Reset them. 808 void remove_self_forwarding_pointers(); 809 810 // Together, these store an object with a preserved mark, and its mark value. 811 Stack<oop, mtGC> _objs_with_preserved_marks; 812 Stack<markOop, mtGC> _preserved_marks_of_objs; 813 814 // Preserve the mark of "obj", if necessary, in preparation for its mark 815 // word being overwritten with a self-forwarding-pointer. 816 void preserve_mark_if_necessary(oop obj, markOop m); 817 818 // The stack of evac-failure objects left to be scanned. 819 GrowableArray<oop>* _evac_failure_scan_stack; 820 // The closure to apply to evac-failure objects. 821 822 OopsInHeapRegionClosure* _evac_failure_closure; 823 // Set the field above. 824 void 825 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 826 _evac_failure_closure = evac_failure_closure; 827 } 828 829 // Push "obj" on the scan stack. 830 void push_on_evac_failure_scan_stack(oop obj); 831 // Process scan stack entries until the stack is empty. 832 void drain_evac_failure_scan_stack(); 833 // True iff an invocation of "drain_scan_stack" is in progress; to 834 // prevent unnecessary recursion. 835 bool _drain_in_progress; 836 837 // Do any necessary initialization for evacuation-failure handling. 838 // "cl" is the closure that will be used to process evac-failure 839 // objects. 840 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 841 // Do any necessary cleanup for evacuation-failure handling data 842 // structures. 843 void finalize_for_evac_failure(); 844 845 // An attempt to evacuate "obj" has failed; take necessary steps. 846 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 847 void handle_evacuation_failure_common(oop obj, markOop m); 848 849 #ifndef PRODUCT 850 // Support for forcing evacuation failures. Analogous to 851 // PromotionFailureALot for the other collectors. 852 853 // Records whether G1EvacuationFailureALot should be in effect 854 // for the current GC 855 bool _evacuation_failure_alot_for_current_gc; 856 857 // Used to record the GC number for interval checking when 858 // determining whether G1EvaucationFailureALot is in effect 859 // for the current GC. 860 size_t _evacuation_failure_alot_gc_number; 861 862 // Count of the number of evacuations between failures. 863 volatile size_t _evacuation_failure_alot_count; 864 865 // Set whether G1EvacuationFailureALot should be in effect 866 // for the current GC (based upon the type of GC and which 867 // command line flags are set); 868 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 869 bool during_initial_mark, 870 bool during_marking); 871 872 inline void set_evacuation_failure_alot_for_current_gc(); 873 874 // Return true if it's time to cause an evacuation failure. 875 inline bool evacuation_should_fail(); 876 877 // Reset the G1EvacuationFailureALot counters. Should be called at 878 // the end of an evacuation pause in which an evacuation failure occurred. 879 inline void reset_evacuation_should_fail(); 880 #endif // !PRODUCT 881 882 // ("Weak") Reference processing support. 883 // 884 // G1 has 2 instances of the reference processor class. One 885 // (_ref_processor_cm) handles reference object discovery 886 // and subsequent processing during concurrent marking cycles. 887 // 888 // The other (_ref_processor_stw) handles reference object 889 // discovery and processing during full GCs and incremental 890 // evacuation pauses. 891 // 892 // During an incremental pause, reference discovery will be 893 // temporarily disabled for _ref_processor_cm and will be 894 // enabled for _ref_processor_stw. At the end of the evacuation 895 // pause references discovered by _ref_processor_stw will be 896 // processed and discovery will be disabled. The previous 897 // setting for reference object discovery for _ref_processor_cm 898 // will be re-instated. 899 // 900 // At the start of marking: 901 // * Discovery by the CM ref processor is verified to be inactive 902 // and it's discovered lists are empty. 903 // * Discovery by the CM ref processor is then enabled. 904 // 905 // At the end of marking: 906 // * Any references on the CM ref processor's discovered 907 // lists are processed (possibly MT). 908 // 909 // At the start of full GC we: 910 // * Disable discovery by the CM ref processor and 911 // empty CM ref processor's discovered lists 912 // (without processing any entries). 913 // * Verify that the STW ref processor is inactive and it's 914 // discovered lists are empty. 915 // * Temporarily set STW ref processor discovery as single threaded. 916 // * Temporarily clear the STW ref processor's _is_alive_non_header 917 // field. 918 // * Finally enable discovery by the STW ref processor. 919 // 920 // The STW ref processor is used to record any discovered 921 // references during the full GC. 922 // 923 // At the end of a full GC we: 924 // * Enqueue any reference objects discovered by the STW ref processor 925 // that have non-live referents. This has the side-effect of 926 // making the STW ref processor inactive by disabling discovery. 927 // * Verify that the CM ref processor is still inactive 928 // and no references have been placed on it's discovered 929 // lists (also checked as a precondition during initial marking). 930 931 // The (stw) reference processor... 932 ReferenceProcessor* _ref_processor_stw; 933 934 STWGCTimer* _gc_timer_stw; 935 ConcurrentGCTimer* _gc_timer_cm; 936 937 G1OldTracer* _gc_tracer_cm; 938 G1NewTracer* _gc_tracer_stw; 939 940 // During reference object discovery, the _is_alive_non_header 941 // closure (if non-null) is applied to the referent object to 942 // determine whether the referent is live. If so then the 943 // reference object does not need to be 'discovered' and can 944 // be treated as a regular oop. This has the benefit of reducing 945 // the number of 'discovered' reference objects that need to 946 // be processed. 947 // 948 // Instance of the is_alive closure for embedding into the 949 // STW reference processor as the _is_alive_non_header field. 950 // Supplying a value for the _is_alive_non_header field is 951 // optional but doing so prevents unnecessary additions to 952 // the discovered lists during reference discovery. 953 G1STWIsAliveClosure _is_alive_closure_stw; 954 955 // The (concurrent marking) reference processor... 956 ReferenceProcessor* _ref_processor_cm; 957 958 // Instance of the concurrent mark is_alive closure for embedding 959 // into the Concurrent Marking reference processor as the 960 // _is_alive_non_header field. Supplying a value for the 961 // _is_alive_non_header field is optional but doing so prevents 962 // unnecessary additions to the discovered lists during reference 963 // discovery. 964 G1CMIsAliveClosure _is_alive_closure_cm; 965 966 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 967 HeapRegion** _worker_cset_start_region; 968 969 // Time stamp to validate the regions recorded in the cache 970 // used by G1CollectedHeap::start_cset_region_for_worker(). 971 // The heap region entry for a given worker is valid iff 972 // the associated time stamp value matches the current value 973 // of G1CollectedHeap::_gc_time_stamp. 974 uint* _worker_cset_start_region_time_stamp; 975 976 volatile bool _free_regions_coming; 977 978 public: 979 980 void set_refine_cte_cl_concurrency(bool concurrent); 981 982 RefToScanQueue *task_queue(uint i) const; 983 984 // A set of cards where updates happened during the GC 985 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 986 987 // A DirtyCardQueueSet that is used to hold cards that contain 988 // references into the current collection set. This is used to 989 // update the remembered sets of the regions in the collection 990 // set in the event of an evacuation failure. 991 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 992 { return _into_cset_dirty_card_queue_set; } 993 994 // Create a G1CollectedHeap with the specified policy. 995 // Must call the initialize method afterwards. 996 // May not return if something goes wrong. 997 G1CollectedHeap(G1CollectorPolicy* policy); 998 999 // Initialize the G1CollectedHeap to have the initial and 1000 // maximum sizes and remembered and barrier sets 1001 // specified by the policy object. 1002 jint initialize(); 1003 1004 virtual void stop(); 1005 1006 // Return the (conservative) maximum heap alignment for any G1 heap 1007 static size_t conservative_max_heap_alignment(); 1008 1009 // Does operations required after initialization has been done. 1010 void post_initialize(); 1011 1012 // Initialize weak reference processing. 1013 void ref_processing_init(); 1014 1015 // Explicitly import set_par_threads into this scope 1016 using CollectedHeap::set_par_threads; 1017 // Set _n_par_threads according to a policy TBD. 1018 void set_par_threads(); 1019 1020 virtual Name kind() const { 1021 return CollectedHeap::G1CollectedHeap; 1022 } 1023 1024 // The current policy object for the collector. 1025 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1026 1027 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1028 1029 // Adaptive size policy. No such thing for g1. 1030 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1031 1032 // The rem set and barrier set. 1033 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1034 1035 unsigned get_gc_time_stamp() { 1036 return _gc_time_stamp; 1037 } 1038 1039 inline void reset_gc_time_stamp(); 1040 1041 void check_gc_time_stamps() PRODUCT_RETURN; 1042 1043 inline void increment_gc_time_stamp(); 1044 1045 // Reset the given region's GC timestamp. If it's starts humongous, 1046 // also reset the GC timestamp of its corresponding 1047 // continues humongous regions too. 1048 void reset_gc_time_stamps(HeapRegion* hr); 1049 1050 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1051 DirtyCardQueue* into_cset_dcq, 1052 bool concurrent, uint worker_i); 1053 1054 // The shared block offset table array. 1055 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1056 1057 // Reference Processing accessors 1058 1059 // The STW reference processor.... 1060 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1061 1062 // The Concurrent Marking reference processor... 1063 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1064 1065 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1066 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1067 1068 virtual size_t capacity() const; 1069 virtual size_t used() const; 1070 // This should be called when we're not holding the heap lock. The 1071 // result might be a bit inaccurate. 1072 size_t used_unlocked() const; 1073 size_t recalculate_used() const; 1074 1075 // These virtual functions do the actual allocation. 1076 // Some heaps may offer a contiguous region for shared non-blocking 1077 // allocation, via inlined code (by exporting the address of the top and 1078 // end fields defining the extent of the contiguous allocation region.) 1079 // But G1CollectedHeap doesn't yet support this. 1080 1081 virtual bool is_maximal_no_gc() const { 1082 return _hrm.available() == 0; 1083 } 1084 1085 // The current number of regions in the heap. 1086 uint num_regions() const { return _hrm.length(); } 1087 1088 // The max number of regions in the heap. 1089 uint max_regions() const { return _hrm.max_length(); } 1090 1091 // The number of regions that are completely free. 1092 uint num_free_regions() const { return _hrm.num_free_regions(); } 1093 1094 MemoryUsage get_auxiliary_data_memory_usage() const { 1095 return _hrm.get_auxiliary_data_memory_usage(); 1096 } 1097 1098 // The number of regions that are not completely free. 1099 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1100 1101 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1102 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1103 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1104 void verify_dirty_young_regions() PRODUCT_RETURN; 1105 1106 #ifndef PRODUCT 1107 // Make sure that the given bitmap has no marked objects in the 1108 // range [from,limit). If it does, print an error message and return 1109 // false. Otherwise, just return true. bitmap_name should be "prev" 1110 // or "next". 1111 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1112 HeapWord* from, HeapWord* limit); 1113 1114 // Verify that the prev / next bitmap range [tams,end) for the given 1115 // region has no marks. Return true if all is well, false if errors 1116 // are detected. 1117 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1118 #endif // PRODUCT 1119 1120 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1121 // the given region do not have any spurious marks. If errors are 1122 // detected, print appropriate error messages and crash. 1123 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1124 1125 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1126 // have any spurious marks. If errors are detected, print 1127 // appropriate error messages and crash. 1128 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1129 1130 // Do sanity check on the contents of the in-cset fast test table. 1131 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1132 1133 // verify_region_sets() performs verification over the region 1134 // lists. It will be compiled in the product code to be used when 1135 // necessary (i.e., during heap verification). 1136 void verify_region_sets(); 1137 1138 // verify_region_sets_optional() is planted in the code for 1139 // list verification in non-product builds (and it can be enabled in 1140 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1141 #if HEAP_REGION_SET_FORCE_VERIFY 1142 void verify_region_sets_optional() { 1143 verify_region_sets(); 1144 } 1145 #else // HEAP_REGION_SET_FORCE_VERIFY 1146 void verify_region_sets_optional() { } 1147 #endif // HEAP_REGION_SET_FORCE_VERIFY 1148 1149 #ifdef ASSERT 1150 bool is_on_master_free_list(HeapRegion* hr) { 1151 return _hrm.is_free(hr); 1152 } 1153 #endif // ASSERT 1154 1155 // Wrapper for the region list operations that can be called from 1156 // methods outside this class. 1157 1158 void secondary_free_list_add(FreeRegionList* list) { 1159 _secondary_free_list.add_ordered(list); 1160 } 1161 1162 void append_secondary_free_list() { 1163 _hrm.insert_list_into_free_list(&_secondary_free_list); 1164 } 1165 1166 void append_secondary_free_list_if_not_empty_with_lock() { 1167 // If the secondary free list looks empty there's no reason to 1168 // take the lock and then try to append it. 1169 if (!_secondary_free_list.is_empty()) { 1170 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1171 append_secondary_free_list(); 1172 } 1173 } 1174 1175 inline void old_set_remove(HeapRegion* hr); 1176 1177 size_t non_young_capacity_bytes() { 1178 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1179 } 1180 1181 void set_free_regions_coming(); 1182 void reset_free_regions_coming(); 1183 bool free_regions_coming() { return _free_regions_coming; } 1184 void wait_while_free_regions_coming(); 1185 1186 // Determine whether the given region is one that we are using as an 1187 // old GC alloc region. 1188 bool is_old_gc_alloc_region(HeapRegion* hr) { 1189 return _allocator->is_retained_old_region(hr); 1190 } 1191 1192 // Perform a collection of the heap; intended for use in implementing 1193 // "System.gc". This probably implies as full a collection as the 1194 // "CollectedHeap" supports. 1195 virtual void collect(GCCause::Cause cause); 1196 1197 // The same as above but assume that the caller holds the Heap_lock. 1198 void collect_locked(GCCause::Cause cause); 1199 1200 virtual bool copy_allocation_context_stats(const jint* contexts, 1201 jlong* totals, 1202 jbyte* accuracy, 1203 jint len); 1204 1205 // True iff an evacuation has failed in the most-recent collection. 1206 bool evacuation_failed() { return _evacuation_failed; } 1207 1208 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1209 void prepend_to_freelist(FreeRegionList* list); 1210 void decrement_summary_bytes(size_t bytes); 1211 1212 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1213 virtual bool is_in(const void* p) const; 1214 #ifdef ASSERT 1215 // Returns whether p is in one of the available areas of the heap. Slow but 1216 // extensive version. 1217 bool is_in_exact(const void* p) const; 1218 #endif 1219 1220 // Return "TRUE" iff the given object address is within the collection 1221 // set. Slow implementation. 1222 inline bool obj_in_cs(oop obj); 1223 1224 inline bool is_in_cset(const HeapRegion *hr); 1225 inline bool is_in_cset(oop obj); 1226 1227 inline bool is_in_cset_or_humongous(const oop obj); 1228 1229 private: 1230 // This array is used for a quick test on whether a reference points into 1231 // the collection set or not. Each of the array's elements denotes whether the 1232 // corresponding region is in the collection set or not. 1233 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1234 1235 public: 1236 1237 inline InCSetState in_cset_state(const oop obj); 1238 1239 // Return "TRUE" iff the given object address is in the reserved 1240 // region of g1. 1241 bool is_in_g1_reserved(const void* p) const { 1242 return _hrm.reserved().contains(p); 1243 } 1244 1245 // Returns a MemRegion that corresponds to the space that has been 1246 // reserved for the heap 1247 MemRegion g1_reserved() const { 1248 return _hrm.reserved(); 1249 } 1250 1251 virtual bool is_in_closed_subset(const void* p) const; 1252 1253 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1254 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1255 } 1256 1257 // This resets the card table to all zeros. It is used after 1258 // a collection pause which used the card table to claim cards. 1259 void cleanUpCardTable(); 1260 1261 // Iteration functions. 1262 1263 // Iterate over all objects, calling "cl.do_object" on each. 1264 virtual void object_iterate(ObjectClosure* cl); 1265 1266 virtual void safe_object_iterate(ObjectClosure* cl) { 1267 object_iterate(cl); 1268 } 1269 1270 // Iterate over heap regions, in address order, terminating the 1271 // iteration early if the "doHeapRegion" method returns "true". 1272 void heap_region_iterate(HeapRegionClosure* blk) const; 1273 1274 // Return the region with the given index. It assumes the index is valid. 1275 inline HeapRegion* region_at(uint index) const; 1276 1277 // Calculate the region index of the given address. Given address must be 1278 // within the heap. 1279 inline uint addr_to_region(HeapWord* addr) const; 1280 1281 inline HeapWord* bottom_addr_for_region(uint index) const; 1282 1283 // Iterate over the heap regions in parallel. Assumes that this will be called 1284 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1285 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1286 // to each of the regions, by attempting to claim the region using the 1287 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1288 // region. The concurrent argument should be set to true if iteration is 1289 // performed concurrently, during which no assumptions are made for consistent 1290 // attributes of the heap regions (as they might be modified while iterating). 1291 void heap_region_par_iterate(HeapRegionClosure* cl, 1292 uint worker_id, 1293 HeapRegionClaimer* hrclaimer, 1294 bool concurrent = false) const; 1295 1296 // Clear the cached cset start regions and (more importantly) 1297 // the time stamps. Called when we reset the GC time stamp. 1298 void clear_cset_start_regions(); 1299 1300 // Given the id of a worker, obtain or calculate a suitable 1301 // starting region for iterating over the current collection set. 1302 HeapRegion* start_cset_region_for_worker(uint worker_i); 1303 1304 // Iterate over the regions (if any) in the current collection set. 1305 void collection_set_iterate(HeapRegionClosure* blk); 1306 1307 // As above but starting from region r 1308 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1309 1310 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1311 1312 // Returns the HeapRegion that contains addr. addr must not be NULL. 1313 template <class T> 1314 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1315 1316 // Returns the HeapRegion that contains addr. addr must not be NULL. 1317 // If addr is within a humongous continues region, it returns its humongous start region. 1318 template <class T> 1319 inline HeapRegion* heap_region_containing(const T addr) const; 1320 1321 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1322 // each address in the (reserved) heap is a member of exactly 1323 // one block. The defining characteristic of a block is that it is 1324 // possible to find its size, and thus to progress forward to the next 1325 // block. (Blocks may be of different sizes.) Thus, blocks may 1326 // represent Java objects, or they might be free blocks in a 1327 // free-list-based heap (or subheap), as long as the two kinds are 1328 // distinguishable and the size of each is determinable. 1329 1330 // Returns the address of the start of the "block" that contains the 1331 // address "addr". We say "blocks" instead of "object" since some heaps 1332 // may not pack objects densely; a chunk may either be an object or a 1333 // non-object. 1334 virtual HeapWord* block_start(const void* addr) const; 1335 1336 // Requires "addr" to be the start of a chunk, and returns its size. 1337 // "addr + size" is required to be the start of a new chunk, or the end 1338 // of the active area of the heap. 1339 virtual size_t block_size(const HeapWord* addr) const; 1340 1341 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1342 // the block is an object. 1343 virtual bool block_is_obj(const HeapWord* addr) const; 1344 1345 // Section on thread-local allocation buffers (TLABs) 1346 // See CollectedHeap for semantics. 1347 1348 bool supports_tlab_allocation() const; 1349 size_t tlab_capacity(Thread* ignored) const; 1350 size_t tlab_used(Thread* ignored) const; 1351 size_t max_tlab_size() const; 1352 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1353 1354 // Can a compiler initialize a new object without store barriers? 1355 // This permission only extends from the creation of a new object 1356 // via a TLAB up to the first subsequent safepoint. If such permission 1357 // is granted for this heap type, the compiler promises to call 1358 // defer_store_barrier() below on any slow path allocation of 1359 // a new object for which such initializing store barriers will 1360 // have been elided. G1, like CMS, allows this, but should be 1361 // ready to provide a compensating write barrier as necessary 1362 // if that storage came out of a non-young region. The efficiency 1363 // of this implementation depends crucially on being able to 1364 // answer very efficiently in constant time whether a piece of 1365 // storage in the heap comes from a young region or not. 1366 // See ReduceInitialCardMarks. 1367 virtual bool can_elide_tlab_store_barriers() const { 1368 return true; 1369 } 1370 1371 virtual bool card_mark_must_follow_store() const { 1372 return true; 1373 } 1374 1375 inline bool is_in_young(const oop obj); 1376 1377 virtual bool is_scavengable(const void* addr); 1378 1379 // We don't need barriers for initializing stores to objects 1380 // in the young gen: for the SATB pre-barrier, there is no 1381 // pre-value that needs to be remembered; for the remembered-set 1382 // update logging post-barrier, we don't maintain remembered set 1383 // information for young gen objects. 1384 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1385 1386 // Returns "true" iff the given word_size is "very large". 1387 static bool is_humongous(size_t word_size) { 1388 // Note this has to be strictly greater-than as the TLABs 1389 // are capped at the humongous threshold and we want to 1390 // ensure that we don't try to allocate a TLAB as 1391 // humongous and that we don't allocate a humongous 1392 // object in a TLAB. 1393 return word_size > _humongous_object_threshold_in_words; 1394 } 1395 1396 // Update mod union table with the set of dirty cards. 1397 void updateModUnion(); 1398 1399 // Set the mod union bits corresponding to the given memRegion. Note 1400 // that this is always a safe operation, since it doesn't clear any 1401 // bits. 1402 void markModUnionRange(MemRegion mr); 1403 1404 // Records the fact that a marking phase is no longer in progress. 1405 void set_marking_complete() { 1406 _mark_in_progress = false; 1407 } 1408 void set_marking_started() { 1409 _mark_in_progress = true; 1410 } 1411 bool mark_in_progress() { 1412 return _mark_in_progress; 1413 } 1414 1415 // Print the maximum heap capacity. 1416 virtual size_t max_capacity() const; 1417 1418 virtual jlong millis_since_last_gc(); 1419 1420 1421 // Convenience function to be used in situations where the heap type can be 1422 // asserted to be this type. 1423 static G1CollectedHeap* heap(); 1424 1425 void set_region_short_lived_locked(HeapRegion* hr); 1426 // add appropriate methods for any other surv rate groups 1427 1428 YoungList* young_list() const { return _young_list; } 1429 1430 // debugging 1431 bool check_young_list_well_formed() { 1432 return _young_list->check_list_well_formed(); 1433 } 1434 1435 bool check_young_list_empty(bool check_heap, 1436 bool check_sample = true); 1437 1438 // *** Stuff related to concurrent marking. It's not clear to me that so 1439 // many of these need to be public. 1440 1441 // The functions below are helper functions that a subclass of 1442 // "CollectedHeap" can use in the implementation of its virtual 1443 // functions. 1444 // This performs a concurrent marking of the live objects in a 1445 // bitmap off to the side. 1446 void doConcurrentMark(); 1447 1448 bool isMarkedPrev(oop obj) const; 1449 bool isMarkedNext(oop obj) const; 1450 1451 // Determine if an object is dead, given the object and also 1452 // the region to which the object belongs. An object is dead 1453 // iff a) it was not allocated since the last mark and b) it 1454 // is not marked. 1455 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1456 return 1457 !hr->obj_allocated_since_prev_marking(obj) && 1458 !isMarkedPrev(obj); 1459 } 1460 1461 // This function returns true when an object has been 1462 // around since the previous marking and hasn't yet 1463 // been marked during this marking. 1464 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1465 return 1466 !hr->obj_allocated_since_next_marking(obj) && 1467 !isMarkedNext(obj); 1468 } 1469 1470 // Determine if an object is dead, given only the object itself. 1471 // This will find the region to which the object belongs and 1472 // then call the region version of the same function. 1473 1474 // Added if it is NULL it isn't dead. 1475 1476 inline bool is_obj_dead(const oop obj) const; 1477 1478 inline bool is_obj_ill(const oop obj) const; 1479 1480 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1481 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1482 bool is_marked(oop obj, VerifyOption vo); 1483 const char* top_at_mark_start_str(VerifyOption vo); 1484 1485 ConcurrentMark* concurrent_mark() const { return _cm; } 1486 1487 // Refinement 1488 1489 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1490 1491 // The dirty cards region list is used to record a subset of regions 1492 // whose cards need clearing. The list if populated during the 1493 // remembered set scanning and drained during the card table 1494 // cleanup. Although the methods are reentrant, population/draining 1495 // phases must not overlap. For synchronization purposes the last 1496 // element on the list points to itself. 1497 HeapRegion* _dirty_cards_region_list; 1498 void push_dirty_cards_region(HeapRegion* hr); 1499 HeapRegion* pop_dirty_cards_region(); 1500 1501 // Optimized nmethod scanning support routines 1502 1503 // Register the given nmethod with the G1 heap. 1504 virtual void register_nmethod(nmethod* nm); 1505 1506 // Unregister the given nmethod from the G1 heap. 1507 virtual void unregister_nmethod(nmethod* nm); 1508 1509 // Free up superfluous code root memory. 1510 void purge_code_root_memory(); 1511 1512 // Rebuild the strong code root lists for each region 1513 // after a full GC. 1514 void rebuild_strong_code_roots(); 1515 1516 // Delete entries for dead interned string and clean up unreferenced symbols 1517 // in symbol table, possibly in parallel. 1518 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1519 1520 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1521 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1522 1523 // Redirty logged cards in the refinement queue. 1524 void redirty_logged_cards(); 1525 // Verification 1526 1527 // The following is just to alert the verification code 1528 // that a full collection has occurred and that the 1529 // remembered sets are no longer up to date. 1530 bool _full_collection; 1531 void set_full_collection() { _full_collection = true;} 1532 void clear_full_collection() {_full_collection = false;} 1533 bool full_collection() {return _full_collection;} 1534 1535 // Perform any cleanup actions necessary before allowing a verification. 1536 virtual void prepare_for_verify(); 1537 1538 // Perform verification. 1539 1540 // vo == UsePrevMarking -> use "prev" marking information, 1541 // vo == UseNextMarking -> use "next" marking information 1542 // vo == UseMarkWord -> use the mark word in the object header 1543 // 1544 // NOTE: Only the "prev" marking information is guaranteed to be 1545 // consistent most of the time, so most calls to this should use 1546 // vo == UsePrevMarking. 1547 // Currently, there is only one case where this is called with 1548 // vo == UseNextMarking, which is to verify the "next" marking 1549 // information at the end of remark. 1550 // Currently there is only one place where this is called with 1551 // vo == UseMarkWord, which is to verify the marking during a 1552 // full GC. 1553 void verify(bool silent, VerifyOption vo); 1554 1555 // Override; it uses the "prev" marking information 1556 virtual void verify(bool silent); 1557 1558 // The methods below are here for convenience and dispatch the 1559 // appropriate method depending on value of the given VerifyOption 1560 // parameter. The values for that parameter, and their meanings, 1561 // are the same as those above. 1562 1563 bool is_obj_dead_cond(const oop obj, 1564 const HeapRegion* hr, 1565 const VerifyOption vo) const; 1566 1567 bool is_obj_dead_cond(const oop obj, 1568 const VerifyOption vo) const; 1569 1570 // Printing 1571 1572 virtual void print_on(outputStream* st) const; 1573 virtual void print_extended_on(outputStream* st) const; 1574 virtual void print_on_error(outputStream* st) const; 1575 1576 virtual void print_gc_threads_on(outputStream* st) const; 1577 virtual void gc_threads_do(ThreadClosure* tc) const; 1578 1579 // Override 1580 void print_tracing_info() const; 1581 1582 // The following two methods are helpful for debugging RSet issues. 1583 void print_cset_rsets() PRODUCT_RETURN; 1584 void print_all_rsets() PRODUCT_RETURN; 1585 1586 public: 1587 size_t pending_card_num(); 1588 size_t cards_scanned(); 1589 1590 protected: 1591 size_t _max_heap_capacity; 1592 }; 1593 1594 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP