1 /* 2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc_implementation/g1/g1AllocationContext.hpp" 29 #include "gc_implementation/g1/g1Allocator.hpp" 30 #include "gc_implementation/g1/concurrentMark.hpp" 31 #include "gc_implementation/g1/evacuationInfo.hpp" 32 #include "gc_implementation/g1/g1AllocRegion.hpp" 33 #include "gc_implementation/g1/g1BiasedArray.hpp" 34 #include "gc_implementation/g1/g1HRPrinter.hpp" 35 #include "gc_implementation/g1/g1InCSetState.hpp" 36 #include "gc_implementation/g1/g1MonitoringSupport.hpp" 37 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp" 38 #include "gc_implementation/g1/g1YCTypes.hpp" 39 #include "gc_implementation/g1/heapRegionManager.hpp" 40 #include "gc_implementation/g1/heapRegionSet.hpp" 41 #include "gc_implementation/shared/hSpaceCounters.hpp" 42 #include "gc_implementation/shared/parGCAllocBuffer.hpp" 43 #include "memory/barrierSet.hpp" 44 #include "memory/memRegion.hpp" 45 #include "memory/sharedHeap.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 G1ScanHeapEvacClosure; 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 79 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 80 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 81 82 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 83 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 84 85 class YoungList : public CHeapObj<mtGC> { 86 private: 87 G1CollectedHeap* _g1h; 88 89 HeapRegion* _head; 90 91 HeapRegion* _survivor_head; 92 HeapRegion* _survivor_tail; 93 94 HeapRegion* _curr; 95 96 uint _length; 97 uint _survivor_length; 98 99 size_t _last_sampled_rs_lengths; 100 size_t _sampled_rs_lengths; 101 102 void empty_list(HeapRegion* list); 103 104 public: 105 YoungList(G1CollectedHeap* g1h); 106 107 void push_region(HeapRegion* hr); 108 void add_survivor_region(HeapRegion* hr); 109 110 void empty_list(); 111 bool is_empty() { return _length == 0; } 112 uint length() { return _length; } 113 uint survivor_length() { return _survivor_length; } 114 115 // Currently we do not keep track of the used byte sum for the 116 // young list and the survivors and it'd be quite a lot of work to 117 // do so. When we'll eventually replace the young list with 118 // instances of HeapRegionLinkedList we'll get that for free. So, 119 // we'll report the more accurate information then. 120 size_t eden_used_bytes() { 121 assert(length() >= survivor_length(), "invariant"); 122 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 123 } 124 size_t survivor_used_bytes() { 125 return (size_t) survivor_length() * HeapRegion::GrainBytes; 126 } 127 128 void rs_length_sampling_init(); 129 bool rs_length_sampling_more(); 130 void rs_length_sampling_next(); 131 132 void reset_sampled_info() { 133 _last_sampled_rs_lengths = 0; 134 } 135 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 136 137 // for development purposes 138 void reset_auxilary_lists(); 139 void clear() { _head = NULL; _length = 0; } 140 141 void clear_survivors() { 142 _survivor_head = NULL; 143 _survivor_tail = NULL; 144 _survivor_length = 0; 145 } 146 147 HeapRegion* first_region() { return _head; } 148 HeapRegion* first_survivor_region() { return _survivor_head; } 149 HeapRegion* last_survivor_region() { return _survivor_tail; } 150 151 // debugging 152 bool check_list_well_formed(); 153 bool check_list_empty(bool check_sample = true); 154 void print(); 155 }; 156 157 // The G1 STW is alive closure. 158 // An instance is embedded into the G1CH and used as the 159 // (optional) _is_alive_non_header closure in the STW 160 // reference processor. It is also extensively used during 161 // reference processing during STW evacuation pauses. 162 class G1STWIsAliveClosure: public BoolObjectClosure { 163 G1CollectedHeap* _g1; 164 public: 165 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 166 bool do_object_b(oop p); 167 }; 168 169 class RefineCardTableEntryClosure; 170 171 class G1RegionMappingChangedListener : public G1MappingChangedListener { 172 private: 173 void reset_from_card_cache(uint start_idx, size_t num_regions); 174 public: 175 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 176 }; 177 178 class G1CollectedHeap : public SharedHeap { 179 friend class VM_CollectForMetadataAllocation; 180 friend class VM_G1CollectForAllocation; 181 friend class VM_G1CollectFull; 182 friend class VM_G1IncCollectionPause; 183 friend class VMStructs; 184 friend class MutatorAllocRegion; 185 friend class SurvivorGCAllocRegion; 186 friend class OldGCAllocRegion; 187 friend class G1Allocator; 188 friend class G1DefaultAllocator; 189 friend class G1ResManAllocator; 190 191 // Closures used in implementation. 192 template <G1Barrier barrier, G1Mark do_mark_object> 193 friend class G1ParCopyClosure; 194 friend class G1IsAliveClosure; 195 friend class G1EvacuateFollowersClosure; 196 friend class G1ParScanThreadState; 197 friend class G1ParScanClosureSuper; 198 friend class G1ParEvacuateFollowersClosure; 199 friend class G1ParTask; 200 friend class G1ParGCAllocator; 201 friend class G1DefaultParGCAllocator; 202 friend class G1FreeGarbageRegionClosure; 203 friend class RefineCardTableEntryClosure; 204 friend class G1PrepareCompactClosure; 205 friend class RegionSorter; 206 friend class RegionResetter; 207 friend class CountRCClosure; 208 friend class EvacPopObjClosure; 209 friend class G1ParCleanupCTTask; 210 211 friend class G1FreeHumongousRegionClosure; 212 // Other related classes. 213 friend class G1MarkSweep; 214 215 // Testing classes. 216 friend class G1CheckCSetFastTableClosure; 217 218 private: 219 // The one and only G1CollectedHeap, so static functions can find it. 220 static G1CollectedHeap* _g1h; 221 222 static size_t _humongous_object_threshold_in_words; 223 224 // The secondary free list which contains regions that have been 225 // freed up during the cleanup process. This will be appended to 226 // the master free list when appropriate. 227 FreeRegionList _secondary_free_list; 228 229 // It keeps track of the old regions. 230 HeapRegionSet _old_set; 231 232 // It keeps track of the humongous regions. 233 HeapRegionSet _humongous_set; 234 235 void eagerly_reclaim_humongous_regions(); 236 237 // The number of regions we could create by expansion. 238 uint _expansion_regions; 239 240 // The block offset table for the G1 heap. 241 G1BlockOffsetSharedArray* _bot_shared; 242 243 // Tears down the region sets / lists so that they are empty and the 244 // regions on the heap do not belong to a region set / list. The 245 // only exception is the humongous set which we leave unaltered. If 246 // free_list_only is true, it will only tear down the master free 247 // list. It is called before a Full GC (free_list_only == false) or 248 // before heap shrinking (free_list_only == true). 249 void tear_down_region_sets(bool free_list_only); 250 251 // Rebuilds the region sets / lists so that they are repopulated to 252 // reflect the contents of the heap. The only exception is the 253 // humongous set which was not torn down in the first place. If 254 // free_list_only is true, it will only rebuild the master free 255 // list. It is called after a Full GC (free_list_only == false) or 256 // after heap shrinking (free_list_only == true). 257 void rebuild_region_sets(bool free_list_only); 258 259 // Callback for region mapping changed events. 260 G1RegionMappingChangedListener _listener; 261 262 // The sequence of all heap regions in the heap. 263 HeapRegionManager _hrm; 264 265 // Class that handles the different kinds of allocations. 266 G1Allocator* _allocator; 267 268 // Statistics for each allocation context 269 AllocationContextStats _allocation_context_stats; 270 271 // PLAB sizing policy for survivors. 272 PLABStats _survivor_plab_stats; 273 274 // PLAB sizing policy for tenured objects. 275 PLABStats _old_plab_stats; 276 277 // It specifies whether we should attempt to expand the heap after a 278 // region allocation failure. If heap expansion fails we set this to 279 // false so that we don't re-attempt the heap expansion (it's likely 280 // that subsequent expansion attempts will also fail if one fails). 281 // Currently, it is only consulted during GC and it's reset at the 282 // start of each GC. 283 bool _expand_heap_after_alloc_failure; 284 285 // It resets the mutator alloc region before new allocations can take place. 286 void init_mutator_alloc_region(); 287 288 // It releases the mutator alloc region. 289 void release_mutator_alloc_region(); 290 291 // It initializes the GC alloc regions at the start of a GC. 292 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 293 294 // It releases the GC alloc regions at the end of a GC. 295 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 296 297 // It does any cleanup that needs to be done on the GC alloc regions 298 // before a Full GC. 299 void abandon_gc_alloc_regions(); 300 301 // Helper for monitoring and management support. 302 G1MonitoringSupport* _g1mm; 303 304 // Records whether the region at the given index is (still) a 305 // candidate for eager reclaim. Only valid for humongous start 306 // regions; other regions have unspecified values. Humongous start 307 // regions are initialized at start of collection pause, with 308 // candidates removed from the set as they are found reachable from 309 // roots or the young generation. 310 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 311 protected: 312 bool default_value() const { return false; } 313 public: 314 void clear() { G1BiasedMappedArray<bool>::clear(); } 315 void set_candidate(uint region, bool value) { 316 set_by_index(region, value); 317 } 318 bool is_candidate(uint region) { 319 return get_by_index(region); 320 } 321 }; 322 323 HumongousReclaimCandidates _humongous_reclaim_candidates; 324 // Stores whether during humongous object registration we found candidate regions. 325 // If not, we can skip a few steps. 326 bool _has_humongous_reclaim_candidates; 327 328 volatile unsigned _gc_time_stamp; 329 330 size_t* _surviving_young_words; 331 332 G1HRPrinter _hr_printer; 333 334 void setup_surviving_young_words(); 335 void update_surviving_young_words(size_t* surv_young_words); 336 void cleanup_surviving_young_words(); 337 338 // It decides whether an explicit GC should start a concurrent cycle 339 // instead of doing a STW GC. Currently, a concurrent cycle is 340 // explicitly started if: 341 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 342 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 343 // (c) cause == _g1_humongous_allocation 344 bool should_do_concurrent_full_gc(GCCause::Cause cause); 345 346 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 347 // concurrent cycles) we have started. 348 volatile uint _old_marking_cycles_started; 349 350 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 351 // concurrent cycles) we have completed. 352 volatile uint _old_marking_cycles_completed; 353 354 bool _concurrent_cycle_started; 355 bool _heap_summary_sent; 356 357 // This is a non-product method that is helpful for testing. It is 358 // called at the end of a GC and artificially expands the heap by 359 // allocating a number of dead regions. This way we can induce very 360 // frequent marking cycles and stress the cleanup / concurrent 361 // cleanup code more (as all the regions that will be allocated by 362 // this method will be found dead by the marking cycle). 363 void allocate_dummy_regions() PRODUCT_RETURN; 364 365 // Clear RSets after a compaction. It also resets the GC time stamps. 366 void clear_rsets_post_compaction(); 367 368 // If the HR printer is active, dump the state of the regions in the 369 // heap after a compaction. 370 void print_hrm_post_compaction(); 371 372 // Create a memory mapper for auxiliary data structures of the given size and 373 // translation factor. 374 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 375 size_t size, 376 size_t translation_factor); 377 378 double verify(bool guard, const char* msg); 379 void verify_before_gc(); 380 void verify_after_gc(); 381 382 void log_gc_header(); 383 void log_gc_footer(double pause_time_sec); 384 385 // These are macros so that, if the assert fires, we get the correct 386 // line number, file, etc. 387 388 #define heap_locking_asserts_err_msg(_extra_message_) \ 389 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 390 (_extra_message_), \ 391 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 392 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 393 BOOL_TO_STR(Thread::current()->is_VM_thread())) 394 395 #define assert_heap_locked() \ 396 do { \ 397 assert(Heap_lock->owned_by_self(), \ 398 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 399 } while (0) 400 401 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 402 do { \ 403 assert(Heap_lock->owned_by_self() || \ 404 (SafepointSynchronize::is_at_safepoint() && \ 405 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 406 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 407 "should be at a safepoint")); \ 408 } while (0) 409 410 #define assert_heap_locked_and_not_at_safepoint() \ 411 do { \ 412 assert(Heap_lock->owned_by_self() && \ 413 !SafepointSynchronize::is_at_safepoint(), \ 414 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 415 "should not be at a safepoint")); \ 416 } while (0) 417 418 #define assert_heap_not_locked() \ 419 do { \ 420 assert(!Heap_lock->owned_by_self(), \ 421 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 422 } while (0) 423 424 #define assert_heap_not_locked_and_not_at_safepoint() \ 425 do { \ 426 assert(!Heap_lock->owned_by_self() && \ 427 !SafepointSynchronize::is_at_safepoint(), \ 428 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 429 "should not be at a safepoint")); \ 430 } while (0) 431 432 #define assert_at_safepoint(_should_be_vm_thread_) \ 433 do { \ 434 assert(SafepointSynchronize::is_at_safepoint() && \ 435 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 436 heap_locking_asserts_err_msg("should be at a safepoint")); \ 437 } while (0) 438 439 #define assert_not_at_safepoint() \ 440 do { \ 441 assert(!SafepointSynchronize::is_at_safepoint(), \ 442 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 443 } while (0) 444 445 protected: 446 447 // The young region list. 448 YoungList* _young_list; 449 450 // The current policy object for the collector. 451 G1CollectorPolicy* _g1_policy; 452 453 // This is the second level of trying to allocate a new region. If 454 // new_region() didn't find a region on the free_list, this call will 455 // check whether there's anything available on the 456 // secondary_free_list and/or wait for more regions to appear on 457 // that list, if _free_regions_coming is set. 458 HeapRegion* new_region_try_secondary_free_list(bool is_old); 459 460 // Try to allocate a single non-humongous HeapRegion sufficient for 461 // an allocation of the given word_size. If do_expand is true, 462 // attempt to expand the heap if necessary to satisfy the allocation 463 // request. If the region is to be used as an old region or for a 464 // humongous object, set is_old to true. If not, to false. 465 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 466 467 // Initialize a contiguous set of free regions of length num_regions 468 // and starting at index first so that they appear as a single 469 // humongous region. 470 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 471 uint num_regions, 472 size_t word_size, 473 AllocationContext_t context); 474 475 // Attempt to allocate a humongous object of the given size. Return 476 // NULL if unsuccessful. 477 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 478 479 // The following two methods, allocate_new_tlab() and 480 // mem_allocate(), are the two main entry points from the runtime 481 // into the G1's allocation routines. They have the following 482 // assumptions: 483 // 484 // * They should both be called outside safepoints. 485 // 486 // * They should both be called without holding the Heap_lock. 487 // 488 // * All allocation requests for new TLABs should go to 489 // allocate_new_tlab(). 490 // 491 // * All non-TLAB allocation requests should go to mem_allocate(). 492 // 493 // * If either call cannot satisfy the allocation request using the 494 // current allocating region, they will try to get a new one. If 495 // this fails, they will attempt to do an evacuation pause and 496 // retry the allocation. 497 // 498 // * If all allocation attempts fail, even after trying to schedule 499 // an evacuation pause, allocate_new_tlab() will return NULL, 500 // whereas mem_allocate() will attempt a heap expansion and/or 501 // schedule a Full GC. 502 // 503 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 504 // should never be called with word_size being humongous. All 505 // humongous allocation requests should go to mem_allocate() which 506 // will satisfy them with a special path. 507 508 virtual HeapWord* allocate_new_tlab(size_t word_size); 509 510 virtual HeapWord* mem_allocate(size_t word_size, 511 bool* gc_overhead_limit_was_exceeded); 512 513 // The following three methods take a gc_count_before_ret 514 // parameter which is used to return the GC count if the method 515 // returns NULL. Given that we are required to read the GC count 516 // while holding the Heap_lock, and these paths will take the 517 // Heap_lock at some point, it's easier to get them to read the GC 518 // count while holding the Heap_lock before they return NULL instead 519 // of the caller (namely: mem_allocate()) having to also take the 520 // Heap_lock just to read the GC count. 521 522 // First-level mutator allocation attempt: try to allocate out of 523 // the mutator alloc region without taking the Heap_lock. This 524 // should only be used for non-humongous allocations. 525 inline HeapWord* attempt_allocation(size_t word_size, 526 uint* gc_count_before_ret, 527 uint* gclocker_retry_count_ret); 528 529 // Second-level mutator allocation attempt: take the Heap_lock and 530 // retry the allocation attempt, potentially scheduling a GC 531 // pause. This should only be used for non-humongous allocations. 532 HeapWord* attempt_allocation_slow(size_t word_size, 533 AllocationContext_t context, 534 uint* gc_count_before_ret, 535 uint* gclocker_retry_count_ret); 536 537 // Takes the Heap_lock and attempts a humongous allocation. It can 538 // potentially schedule a GC pause. 539 HeapWord* attempt_allocation_humongous(size_t word_size, 540 uint* gc_count_before_ret, 541 uint* gclocker_retry_count_ret); 542 543 // Allocation attempt that should be called during safepoints (e.g., 544 // at the end of a successful GC). expect_null_mutator_alloc_region 545 // specifies whether the mutator alloc region is expected to be NULL 546 // or not. 547 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 548 AllocationContext_t context, 549 bool expect_null_mutator_alloc_region); 550 551 // It dirties the cards that cover the block so that so that the post 552 // write barrier never queues anything when updating objects on this 553 // block. It is assumed (and in fact we assert) that the block 554 // belongs to a young region. 555 inline void dirty_young_block(HeapWord* start, size_t word_size); 556 557 // Allocate blocks during garbage collection. Will ensure an 558 // allocation region, either by picking one or expanding the 559 // heap, and then allocate a block of the given size. The block 560 // may not be a humongous - it must fit into a single heap region. 561 inline HeapWord* par_allocate_during_gc(InCSetState dest, 562 size_t word_size, 563 AllocationContext_t context); 564 // Ensure that no further allocations can happen in "r", bearing in mind 565 // that parallel threads might be attempting allocations. 566 void par_allocate_remaining_space(HeapRegion* r); 567 568 // Allocation attempt during GC for a survivor object / PLAB. 569 inline HeapWord* survivor_attempt_allocation(size_t word_size, 570 AllocationContext_t context); 571 572 // Allocation attempt during GC for an old object / PLAB. 573 inline HeapWord* old_attempt_allocation(size_t word_size, 574 AllocationContext_t context); 575 576 // These methods are the "callbacks" from the G1AllocRegion class. 577 578 // For mutator alloc regions. 579 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 580 void retire_mutator_alloc_region(HeapRegion* alloc_region, 581 size_t allocated_bytes); 582 583 // For GC alloc regions. 584 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 585 InCSetState dest); 586 void retire_gc_alloc_region(HeapRegion* alloc_region, 587 size_t allocated_bytes, InCSetState dest); 588 589 // - if explicit_gc is true, the GC is for a System.gc() or a heap 590 // inspection request and should collect the entire heap 591 // - if clear_all_soft_refs is true, all soft references should be 592 // cleared during the GC 593 // - if explicit_gc is false, word_size describes the allocation that 594 // the GC should attempt (at least) to satisfy 595 // - it returns false if it is unable to do the collection due to the 596 // GC locker being active, true otherwise 597 bool do_collection(bool explicit_gc, 598 bool clear_all_soft_refs, 599 size_t word_size); 600 601 // Callback from VM_G1CollectFull operation. 602 // Perform a full collection. 603 virtual void do_full_collection(bool clear_all_soft_refs); 604 605 // Resize the heap if necessary after a full collection. If this is 606 // after a collect-for allocation, "word_size" is the allocation size, 607 // and will be considered part of the used portion of the heap. 608 void resize_if_necessary_after_full_collection(size_t word_size); 609 610 // Callback from VM_G1CollectForAllocation operation. 611 // This function does everything necessary/possible to satisfy a 612 // failed allocation request (including collection, expansion, etc.) 613 HeapWord* satisfy_failed_allocation(size_t word_size, 614 AllocationContext_t context, 615 bool* succeeded); 616 617 // Attempting to expand the heap sufficiently 618 // to support an allocation of the given "word_size". If 619 // successful, perform the allocation and return the address of the 620 // allocated block, or else "NULL". 621 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 622 623 // Process any reference objects discovered during 624 // an incremental evacuation pause. 625 void process_discovered_references(uint no_of_gc_workers); 626 627 // Enqueue any remaining discovered references 628 // after processing. 629 void enqueue_discovered_references(uint no_of_gc_workers); 630 631 public: 632 633 G1Allocator* allocator() { 634 return _allocator; 635 } 636 637 G1MonitoringSupport* g1mm() { 638 assert(_g1mm != NULL, "should have been initialized"); 639 return _g1mm; 640 } 641 642 // Expand the garbage-first heap by at least the given size (in bytes!). 643 // Returns true if the heap was expanded by the requested amount; 644 // false otherwise. 645 // (Rounds up to a HeapRegion boundary.) 646 bool expand(size_t expand_bytes); 647 648 // Returns the PLAB statistics for a given destination. 649 inline PLABStats* alloc_buffer_stats(InCSetState dest); 650 651 // Determines PLAB size for a given destination. 652 inline size_t desired_plab_sz(InCSetState dest); 653 654 inline AllocationContextStats& allocation_context_stats(); 655 656 // Do anything common to GC's. 657 virtual void gc_prologue(bool full); 658 virtual void gc_epilogue(bool full); 659 660 // Modify the reclaim candidate set and test for presence. 661 // These are only valid for starts_humongous regions. 662 inline void set_humongous_reclaim_candidate(uint region, bool value); 663 inline bool is_humongous_reclaim_candidate(uint region); 664 665 // Remove from the reclaim candidate set. Also remove from the 666 // collection set so that later encounters avoid the slow path. 667 inline void set_humongous_is_live(oop obj); 668 669 // Register the given region to be part of the collection set. 670 inline void register_humongous_region_with_in_cset_fast_test(uint index); 671 // Register regions with humongous objects (actually on the start region) in 672 // the in_cset_fast_test table. 673 void register_humongous_regions_with_in_cset_fast_test(); 674 // We register a region with the fast "in collection set" test. We 675 // simply set to true the array slot corresponding to this region. 676 void register_young_region_with_in_cset_fast_test(HeapRegion* r) { 677 _in_cset_fast_test.set_in_young(r->hrm_index()); 678 } 679 void register_old_region_with_in_cset_fast_test(HeapRegion* r) { 680 _in_cset_fast_test.set_in_old(r->hrm_index()); 681 } 682 683 // This is a fast test on whether a reference points into the 684 // collection set or not. Assume that the reference 685 // points into the heap. 686 inline bool in_cset_fast_test(oop obj); 687 688 void clear_cset_fast_test() { 689 _in_cset_fast_test.clear(); 690 } 691 692 // This is called at the start of either a concurrent cycle or a Full 693 // GC to update the number of old marking cycles started. 694 void increment_old_marking_cycles_started(); 695 696 // This is called at the end of either a concurrent cycle or a Full 697 // GC to update the number of old marking cycles completed. Those two 698 // can happen in a nested fashion, i.e., we start a concurrent 699 // cycle, a Full GC happens half-way through it which ends first, 700 // and then the cycle notices that a Full GC happened and ends 701 // too. The concurrent parameter is a boolean to help us do a bit 702 // tighter consistency checking in the method. If concurrent is 703 // false, the caller is the inner caller in the nesting (i.e., the 704 // Full GC). If concurrent is true, the caller is the outer caller 705 // in this nesting (i.e., the concurrent cycle). Further nesting is 706 // not currently supported. The end of this call also notifies 707 // the FullGCCount_lock in case a Java thread is waiting for a full 708 // GC to happen (e.g., it called System.gc() with 709 // +ExplicitGCInvokesConcurrent). 710 void increment_old_marking_cycles_completed(bool concurrent); 711 712 uint old_marking_cycles_completed() { 713 return _old_marking_cycles_completed; 714 } 715 716 void register_concurrent_cycle_start(const Ticks& start_time); 717 void register_concurrent_cycle_end(); 718 void trace_heap_after_concurrent_cycle(); 719 720 G1YCType yc_type(); 721 722 G1HRPrinter* hr_printer() { return &_hr_printer; } 723 724 // Frees a non-humongous region by initializing its contents and 725 // adding it to the free list that's passed as a parameter (this is 726 // usually a local list which will be appended to the master free 727 // list later). The used bytes of freed regions are accumulated in 728 // pre_used. If par is true, the region's RSet will not be freed 729 // up. The assumption is that this will be done later. 730 // The locked parameter indicates if the caller has already taken 731 // care of proper synchronization. This may allow some optimizations. 732 void free_region(HeapRegion* hr, 733 FreeRegionList* free_list, 734 bool par, 735 bool locked = false); 736 737 // Frees a humongous region by collapsing it into individual regions 738 // and calling free_region() for each of them. The freed regions 739 // will be added to the free list that's passed as a parameter (this 740 // is usually a local list which will be appended to the master free 741 // list later). The used bytes of freed regions are accumulated in 742 // pre_used. If par is true, the region's RSet will not be freed 743 // up. The assumption is that this will be done later. 744 void free_humongous_region(HeapRegion* hr, 745 FreeRegionList* free_list, 746 bool par); 747 protected: 748 749 // Shrink the garbage-first heap by at most the given size (in bytes!). 750 // (Rounds down to a HeapRegion boundary.) 751 virtual void shrink(size_t expand_bytes); 752 void shrink_helper(size_t expand_bytes); 753 754 #if TASKQUEUE_STATS 755 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 756 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 757 void reset_taskqueue_stats(); 758 #endif // TASKQUEUE_STATS 759 760 // Schedule the VM operation that will do an evacuation pause to 761 // satisfy an allocation request of word_size. *succeeded will 762 // return whether the VM operation was successful (it did do an 763 // evacuation pause) or not (another thread beat us to it or the GC 764 // locker was active). Given that we should not be holding the 765 // Heap_lock when we enter this method, we will pass the 766 // gc_count_before (i.e., total_collections()) as a parameter since 767 // it has to be read while holding the Heap_lock. Currently, both 768 // methods that call do_collection_pause() release the Heap_lock 769 // before the call, so it's easy to read gc_count_before just before. 770 HeapWord* do_collection_pause(size_t word_size, 771 uint gc_count_before, 772 bool* succeeded, 773 GCCause::Cause gc_cause); 774 775 // The guts of the incremental collection pause, executed by the vm 776 // thread. It returns false if it is unable to do the collection due 777 // to the GC locker being active, true otherwise 778 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 779 780 // Actually do the work of evacuating the collection set. 781 void evacuate_collection_set(EvacuationInfo& evacuation_info); 782 783 // The g1 remembered set of the heap. 784 G1RemSet* _g1_rem_set; 785 786 // A set of cards that cover the objects for which the Rsets should be updated 787 // concurrently after the collection. 788 DirtyCardQueueSet _dirty_card_queue_set; 789 790 // The closure used to refine a single card. 791 RefineCardTableEntryClosure* _refine_cte_cl; 792 793 // A function to check the consistency of dirty card logs. 794 void check_ct_logs_at_safepoint(); 795 796 // A DirtyCardQueueSet that is used to hold cards that contain 797 // references into the current collection set. This is used to 798 // update the remembered sets of the regions in the collection 799 // set in the event of an evacuation failure. 800 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 801 802 // After a collection pause, make the regions in the CS into free 803 // regions. 804 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 805 806 // Abandon the current collection set without recording policy 807 // statistics or updating free lists. 808 void abandon_collection_set(HeapRegion* cs_head); 809 810 // The concurrent marker (and the thread it runs in.) 811 ConcurrentMark* _cm; 812 ConcurrentMarkThread* _cmThread; 813 bool _mark_in_progress; 814 815 // The concurrent refiner. 816 ConcurrentG1Refine* _cg1r; 817 818 // The parallel task queues 819 RefToScanQueueSet *_task_queues; 820 821 // True iff a evacuation has failed in the current collection. 822 bool _evacuation_failed; 823 824 EvacuationFailedInfo* _evacuation_failed_info_array; 825 826 // Failed evacuations cause some logical from-space objects to have 827 // forwarding pointers to themselves. Reset them. 828 void remove_self_forwarding_pointers(); 829 830 // Together, these store an object with a preserved mark, and its mark value. 831 Stack<oop, mtGC> _objs_with_preserved_marks; 832 Stack<markOop, mtGC> _preserved_marks_of_objs; 833 834 // Preserve the mark of "obj", if necessary, in preparation for its mark 835 // word being overwritten with a self-forwarding-pointer. 836 void preserve_mark_if_necessary(oop obj, markOop m); 837 838 // The stack of evac-failure objects left to be scanned. 839 GrowableArray<oop>* _evac_failure_scan_stack; 840 // The closure to apply to evac-failure objects. 841 842 OopsInHeapRegionClosure* _evac_failure_closure; 843 // Set the field above. 844 void 845 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 846 _evac_failure_closure = evac_failure_closure; 847 } 848 849 // Push "obj" on the scan stack. 850 void push_on_evac_failure_scan_stack(oop obj); 851 // Process scan stack entries until the stack is empty. 852 void drain_evac_failure_scan_stack(); 853 // True iff an invocation of "drain_scan_stack" is in progress; to 854 // prevent unnecessary recursion. 855 bool _drain_in_progress; 856 857 // Do any necessary initialization for evacuation-failure handling. 858 // "cl" is the closure that will be used to process evac-failure 859 // objects. 860 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 861 // Do any necessary cleanup for evacuation-failure handling data 862 // structures. 863 void finalize_for_evac_failure(); 864 865 // An attempt to evacuate "obj" has failed; take necessary steps. 866 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 867 void handle_evacuation_failure_common(oop obj, markOop m); 868 869 #ifndef PRODUCT 870 // Support for forcing evacuation failures. Analogous to 871 // PromotionFailureALot for the other collectors. 872 873 // Records whether G1EvacuationFailureALot should be in effect 874 // for the current GC 875 bool _evacuation_failure_alot_for_current_gc; 876 877 // Used to record the GC number for interval checking when 878 // determining whether G1EvaucationFailureALot is in effect 879 // for the current GC. 880 size_t _evacuation_failure_alot_gc_number; 881 882 // Count of the number of evacuations between failures. 883 volatile size_t _evacuation_failure_alot_count; 884 885 // Set whether G1EvacuationFailureALot should be in effect 886 // for the current GC (based upon the type of GC and which 887 // command line flags are set); 888 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 889 bool during_initial_mark, 890 bool during_marking); 891 892 inline void set_evacuation_failure_alot_for_current_gc(); 893 894 // Return true if it's time to cause an evacuation failure. 895 inline bool evacuation_should_fail(); 896 897 // Reset the G1EvacuationFailureALot counters. Should be called at 898 // the end of an evacuation pause in which an evacuation failure occurred. 899 inline void reset_evacuation_should_fail(); 900 #endif // !PRODUCT 901 902 // ("Weak") Reference processing support. 903 // 904 // G1 has 2 instances of the reference processor class. One 905 // (_ref_processor_cm) handles reference object discovery 906 // and subsequent processing during concurrent marking cycles. 907 // 908 // The other (_ref_processor_stw) handles reference object 909 // discovery and processing during full GCs and incremental 910 // evacuation pauses. 911 // 912 // During an incremental pause, reference discovery will be 913 // temporarily disabled for _ref_processor_cm and will be 914 // enabled for _ref_processor_stw. At the end of the evacuation 915 // pause references discovered by _ref_processor_stw will be 916 // processed and discovery will be disabled. The previous 917 // setting for reference object discovery for _ref_processor_cm 918 // will be re-instated. 919 // 920 // At the start of marking: 921 // * Discovery by the CM ref processor is verified to be inactive 922 // and it's discovered lists are empty. 923 // * Discovery by the CM ref processor is then enabled. 924 // 925 // At the end of marking: 926 // * Any references on the CM ref processor's discovered 927 // lists are processed (possibly MT). 928 // 929 // At the start of full GC we: 930 // * Disable discovery by the CM ref processor and 931 // empty CM ref processor's discovered lists 932 // (without processing any entries). 933 // * Verify that the STW ref processor is inactive and it's 934 // discovered lists are empty. 935 // * Temporarily set STW ref processor discovery as single threaded. 936 // * Temporarily clear the STW ref processor's _is_alive_non_header 937 // field. 938 // * Finally enable discovery by the STW ref processor. 939 // 940 // The STW ref processor is used to record any discovered 941 // references during the full GC. 942 // 943 // At the end of a full GC we: 944 // * Enqueue any reference objects discovered by the STW ref processor 945 // that have non-live referents. This has the side-effect of 946 // making the STW ref processor inactive by disabling discovery. 947 // * Verify that the CM ref processor is still inactive 948 // and no references have been placed on it's discovered 949 // lists (also checked as a precondition during initial marking). 950 951 // The (stw) reference processor... 952 ReferenceProcessor* _ref_processor_stw; 953 954 STWGCTimer* _gc_timer_stw; 955 ConcurrentGCTimer* _gc_timer_cm; 956 957 G1OldTracer* _gc_tracer_cm; 958 G1NewTracer* _gc_tracer_stw; 959 960 // During reference object discovery, the _is_alive_non_header 961 // closure (if non-null) is applied to the referent object to 962 // determine whether the referent is live. If so then the 963 // reference object does not need to be 'discovered' and can 964 // be treated as a regular oop. This has the benefit of reducing 965 // the number of 'discovered' reference objects that need to 966 // be processed. 967 // 968 // Instance of the is_alive closure for embedding into the 969 // STW reference processor as the _is_alive_non_header field. 970 // Supplying a value for the _is_alive_non_header field is 971 // optional but doing so prevents unnecessary additions to 972 // the discovered lists during reference discovery. 973 G1STWIsAliveClosure _is_alive_closure_stw; 974 975 // The (concurrent marking) reference processor... 976 ReferenceProcessor* _ref_processor_cm; 977 978 // Instance of the concurrent mark is_alive closure for embedding 979 // into the Concurrent Marking reference processor as the 980 // _is_alive_non_header field. Supplying a value for the 981 // _is_alive_non_header field is optional but doing so prevents 982 // unnecessary additions to the discovered lists during reference 983 // discovery. 984 G1CMIsAliveClosure _is_alive_closure_cm; 985 986 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 987 HeapRegion** _worker_cset_start_region; 988 989 // Time stamp to validate the regions recorded in the cache 990 // used by G1CollectedHeap::start_cset_region_for_worker(). 991 // The heap region entry for a given worker is valid iff 992 // the associated time stamp value matches the current value 993 // of G1CollectedHeap::_gc_time_stamp. 994 uint* _worker_cset_start_region_time_stamp; 995 996 volatile bool _free_regions_coming; 997 998 public: 999 1000 void set_refine_cte_cl_concurrency(bool concurrent); 1001 1002 RefToScanQueue *task_queue(int i) const; 1003 1004 // A set of cards where updates happened during the GC 1005 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1006 1007 // A DirtyCardQueueSet that is used to hold cards that contain 1008 // references into the current collection set. This is used to 1009 // update the remembered sets of the regions in the collection 1010 // set in the event of an evacuation failure. 1011 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1012 { return _into_cset_dirty_card_queue_set; } 1013 1014 // Create a G1CollectedHeap with the specified policy. 1015 // Must call the initialize method afterwards. 1016 // May not return if something goes wrong. 1017 G1CollectedHeap(G1CollectorPolicy* policy); 1018 1019 // Initialize the G1CollectedHeap to have the initial and 1020 // maximum sizes and remembered and barrier sets 1021 // specified by the policy object. 1022 jint initialize(); 1023 1024 virtual void stop(); 1025 1026 // Return the (conservative) maximum heap alignment for any G1 heap 1027 static size_t conservative_max_heap_alignment(); 1028 1029 // Initialize weak reference processing. 1030 virtual void ref_processing_init(); 1031 1032 // Explicitly import set_par_threads into this scope 1033 using SharedHeap::set_par_threads; 1034 // Set _n_par_threads according to a policy TBD. 1035 void set_par_threads(); 1036 1037 virtual CollectedHeap::Name kind() const { 1038 return CollectedHeap::G1CollectedHeap; 1039 } 1040 1041 // The current policy object for the collector. 1042 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1043 1044 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1045 1046 // Adaptive size policy. No such thing for g1. 1047 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1048 1049 // The rem set and barrier set. 1050 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1051 1052 unsigned get_gc_time_stamp() { 1053 return _gc_time_stamp; 1054 } 1055 1056 inline void reset_gc_time_stamp(); 1057 1058 void check_gc_time_stamps() PRODUCT_RETURN; 1059 1060 inline void increment_gc_time_stamp(); 1061 1062 // Reset the given region's GC timestamp. If it's starts humongous, 1063 // also reset the GC timestamp of its corresponding 1064 // continues humongous regions too. 1065 void reset_gc_time_stamps(HeapRegion* hr); 1066 1067 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1068 DirtyCardQueue* into_cset_dcq, 1069 bool concurrent, uint worker_i); 1070 1071 // The shared block offset table array. 1072 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1073 1074 // Reference Processing accessors 1075 1076 // The STW reference processor.... 1077 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1078 1079 // The Concurrent Marking reference processor... 1080 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1081 1082 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1083 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1084 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1085 1086 virtual size_t capacity() const; 1087 virtual size_t used() const; 1088 // This should be called when we're not holding the heap lock. The 1089 // result might be a bit inaccurate. 1090 size_t used_unlocked() const; 1091 size_t recalculate_used() const; 1092 1093 // These virtual functions do the actual allocation. 1094 // Some heaps may offer a contiguous region for shared non-blocking 1095 // allocation, via inlined code (by exporting the address of the top and 1096 // end fields defining the extent of the contiguous allocation region.) 1097 // But G1CollectedHeap doesn't yet support this. 1098 1099 virtual bool is_maximal_no_gc() const { 1100 return _hrm.available() == 0; 1101 } 1102 1103 // The current number of regions in the heap. 1104 uint num_regions() const { return _hrm.length(); } 1105 1106 // The max number of regions in the heap. 1107 uint max_regions() const { return _hrm.max_length(); } 1108 1109 // The number of regions that are completely free. 1110 uint num_free_regions() const { return _hrm.num_free_regions(); } 1111 1112 MemoryUsage get_auxiliary_data_memory_usage() const { 1113 return _hrm.get_auxiliary_data_memory_usage(); 1114 } 1115 1116 // The number of regions that are not completely free. 1117 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1118 1119 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1120 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1121 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1122 void verify_dirty_young_regions() PRODUCT_RETURN; 1123 1124 #ifndef PRODUCT 1125 // Make sure that the given bitmap has no marked objects in the 1126 // range [from,limit). If it does, print an error message and return 1127 // false. Otherwise, just return true. bitmap_name should be "prev" 1128 // or "next". 1129 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1130 HeapWord* from, HeapWord* limit); 1131 1132 // Verify that the prev / next bitmap range [tams,end) for the given 1133 // region has no marks. Return true if all is well, false if errors 1134 // are detected. 1135 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1136 #endif // PRODUCT 1137 1138 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1139 // the given region do not have any spurious marks. If errors are 1140 // detected, print appropriate error messages and crash. 1141 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1142 1143 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1144 // have any spurious marks. If errors are detected, print 1145 // appropriate error messages and crash. 1146 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1147 1148 // Do sanity check on the contents of the in-cset fast test table. 1149 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1150 1151 // verify_region_sets() performs verification over the region 1152 // lists. It will be compiled in the product code to be used when 1153 // necessary (i.e., during heap verification). 1154 void verify_region_sets(); 1155 1156 // verify_region_sets_optional() is planted in the code for 1157 // list verification in non-product builds (and it can be enabled in 1158 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1159 #if HEAP_REGION_SET_FORCE_VERIFY 1160 void verify_region_sets_optional() { 1161 verify_region_sets(); 1162 } 1163 #else // HEAP_REGION_SET_FORCE_VERIFY 1164 void verify_region_sets_optional() { } 1165 #endif // HEAP_REGION_SET_FORCE_VERIFY 1166 1167 #ifdef ASSERT 1168 bool is_on_master_free_list(HeapRegion* hr) { 1169 return _hrm.is_free(hr); 1170 } 1171 #endif // ASSERT 1172 1173 // Wrapper for the region list operations that can be called from 1174 // methods outside this class. 1175 1176 void secondary_free_list_add(FreeRegionList* list) { 1177 _secondary_free_list.add_ordered(list); 1178 } 1179 1180 void append_secondary_free_list() { 1181 _hrm.insert_list_into_free_list(&_secondary_free_list); 1182 } 1183 1184 void append_secondary_free_list_if_not_empty_with_lock() { 1185 // If the secondary free list looks empty there's no reason to 1186 // take the lock and then try to append it. 1187 if (!_secondary_free_list.is_empty()) { 1188 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1189 append_secondary_free_list(); 1190 } 1191 } 1192 1193 inline void old_set_remove(HeapRegion* hr); 1194 1195 size_t non_young_capacity_bytes() { 1196 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1197 } 1198 1199 void set_free_regions_coming(); 1200 void reset_free_regions_coming(); 1201 bool free_regions_coming() { return _free_regions_coming; } 1202 void wait_while_free_regions_coming(); 1203 1204 // Determine whether the given region is one that we are using as an 1205 // old GC alloc region. 1206 bool is_old_gc_alloc_region(HeapRegion* hr) { 1207 return _allocator->is_retained_old_region(hr); 1208 } 1209 1210 // Perform a collection of the heap; intended for use in implementing 1211 // "System.gc". This probably implies as full a collection as the 1212 // "CollectedHeap" supports. 1213 virtual void collect(GCCause::Cause cause); 1214 1215 // The same as above but assume that the caller holds the Heap_lock. 1216 void collect_locked(GCCause::Cause cause); 1217 1218 virtual bool copy_allocation_context_stats(const jint* contexts, 1219 jlong* totals, 1220 jbyte* accuracy, 1221 jint len); 1222 1223 // True iff an evacuation has failed in the most-recent collection. 1224 bool evacuation_failed() { return _evacuation_failed; } 1225 1226 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1227 void prepend_to_freelist(FreeRegionList* list); 1228 void decrement_summary_bytes(size_t bytes); 1229 1230 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1231 virtual bool is_in(const void* p) const; 1232 #ifdef ASSERT 1233 // Returns whether p is in one of the available areas of the heap. Slow but 1234 // extensive version. 1235 bool is_in_exact(const void* p) const; 1236 #endif 1237 1238 // Return "TRUE" iff the given object address is within the collection 1239 // set. Slow implementation. 1240 inline bool obj_in_cs(oop obj); 1241 1242 inline bool is_in_cset(oop obj); 1243 1244 inline bool is_in_cset_or_humongous(const oop obj); 1245 1246 private: 1247 // This array is used for a quick test on whether a reference points into 1248 // the collection set or not. Each of the array's elements denotes whether the 1249 // corresponding region is in the collection set or not. 1250 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1251 1252 public: 1253 1254 inline InCSetState in_cset_state(const oop obj); 1255 1256 // Return "TRUE" iff the given object address is in the reserved 1257 // region of g1. 1258 bool is_in_g1_reserved(const void* p) const { 1259 return _hrm.reserved().contains(p); 1260 } 1261 1262 // Returns a MemRegion that corresponds to the space that has been 1263 // reserved for the heap 1264 MemRegion g1_reserved() const { 1265 return _hrm.reserved(); 1266 } 1267 1268 virtual bool is_in_closed_subset(const void* p) const; 1269 1270 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1271 return (G1SATBCardTableLoggingModRefBS*) barrier_set(); 1272 } 1273 1274 // This resets the card table to all zeros. It is used after 1275 // a collection pause which used the card table to claim cards. 1276 void cleanUpCardTable(); 1277 1278 // Iteration functions. 1279 1280 // Iterate over all the ref-containing fields of all objects, calling 1281 // "cl.do_oop" on each. 1282 virtual void oop_iterate(ExtendedOopClosure* cl); 1283 1284 // Iterate over all objects, calling "cl.do_object" on each. 1285 virtual void object_iterate(ObjectClosure* cl); 1286 1287 virtual void safe_object_iterate(ObjectClosure* cl) { 1288 object_iterate(cl); 1289 } 1290 1291 // Iterate over all spaces in use in the heap, in ascending address order. 1292 virtual void space_iterate(SpaceClosure* cl); 1293 1294 // Iterate over heap regions, in address order, terminating the 1295 // iteration early if the "doHeapRegion" method returns "true". 1296 void heap_region_iterate(HeapRegionClosure* blk) const; 1297 1298 // Return the region with the given index. It assumes the index is valid. 1299 inline HeapRegion* region_at(uint index) const; 1300 1301 // Calculate the region index of the given address. Given address must be 1302 // within the heap. 1303 inline uint addr_to_region(HeapWord* addr) const; 1304 1305 inline HeapWord* bottom_addr_for_region(uint index) const; 1306 1307 // Divide the heap region sequence into "chunks" of some size (the number 1308 // of regions divided by the number of parallel threads times some 1309 // overpartition factor, currently 4). Assumes that this will be called 1310 // in parallel by ParallelGCThreads worker threads with discinct worker 1311 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1312 // calls will use the same "claim_value", and that that claim value is 1313 // different from the claim_value of any heap region before the start of 1314 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1315 // attempting to claim the first region in each chunk, and, if 1316 // successful, applying the closure to each region in the chunk (and 1317 // setting the claim value of the second and subsequent regions of the 1318 // chunk.) For now requires that "doHeapRegion" always returns "false", 1319 // i.e., that a closure never attempt to abort a traversal. 1320 void heap_region_par_iterate_chunked(HeapRegionClosure* cl, 1321 uint worker_id, 1322 uint num_workers, 1323 jint claim_value) const; 1324 1325 // It resets all the region claim values to the default. 1326 void reset_heap_region_claim_values(); 1327 1328 // Resets the claim values of regions in the current 1329 // collection set to the default. 1330 void reset_cset_heap_region_claim_values(); 1331 1332 #ifdef ASSERT 1333 bool check_heap_region_claim_values(jint claim_value); 1334 1335 // Same as the routine above but only checks regions in the 1336 // current collection set. 1337 bool check_cset_heap_region_claim_values(jint claim_value); 1338 #endif // ASSERT 1339 1340 // Clear the cached cset start regions and (more importantly) 1341 // the time stamps. Called when we reset the GC time stamp. 1342 void clear_cset_start_regions(); 1343 1344 // Given the id of a worker, obtain or calculate a suitable 1345 // starting region for iterating over the current collection set. 1346 HeapRegion* start_cset_region_for_worker(uint worker_i); 1347 1348 // Iterate over the regions (if any) in the current collection set. 1349 void collection_set_iterate(HeapRegionClosure* blk); 1350 1351 // As above but starting from region r 1352 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1353 1354 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1355 1356 // A CollectedHeap will contain some number of spaces. This finds the 1357 // space containing a given address, or else returns NULL. 1358 virtual Space* space_containing(const void* addr) const; 1359 1360 // Returns the HeapRegion that contains addr. addr must not be NULL. 1361 template <class T> 1362 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1363 1364 // Returns the HeapRegion that contains addr. addr must not be NULL. 1365 // If addr is within a humongous continues region, it returns its humongous start region. 1366 template <class T> 1367 inline HeapRegion* heap_region_containing(const T addr) const; 1368 1369 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1370 // each address in the (reserved) heap is a member of exactly 1371 // one block. The defining characteristic of a block is that it is 1372 // possible to find its size, and thus to progress forward to the next 1373 // block. (Blocks may be of different sizes.) Thus, blocks may 1374 // represent Java objects, or they might be free blocks in a 1375 // free-list-based heap (or subheap), as long as the two kinds are 1376 // distinguishable and the size of each is determinable. 1377 1378 // Returns the address of the start of the "block" that contains the 1379 // address "addr". We say "blocks" instead of "object" since some heaps 1380 // may not pack objects densely; a chunk may either be an object or a 1381 // non-object. 1382 virtual HeapWord* block_start(const void* addr) const; 1383 1384 // Requires "addr" to be the start of a chunk, and returns its size. 1385 // "addr + size" is required to be the start of a new chunk, or the end 1386 // of the active area of the heap. 1387 virtual size_t block_size(const HeapWord* addr) const; 1388 1389 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1390 // the block is an object. 1391 virtual bool block_is_obj(const HeapWord* addr) const; 1392 1393 // Does this heap support heap inspection? (+PrintClassHistogram) 1394 virtual bool supports_heap_inspection() const { return true; } 1395 1396 // Section on thread-local allocation buffers (TLABs) 1397 // See CollectedHeap for semantics. 1398 1399 bool supports_tlab_allocation() const; 1400 size_t tlab_capacity(Thread* ignored) const; 1401 size_t tlab_used(Thread* ignored) const; 1402 size_t max_tlab_size() const; 1403 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1404 1405 // Can a compiler initialize a new object without store barriers? 1406 // This permission only extends from the creation of a new object 1407 // via a TLAB up to the first subsequent safepoint. If such permission 1408 // is granted for this heap type, the compiler promises to call 1409 // defer_store_barrier() below on any slow path allocation of 1410 // a new object for which such initializing store barriers will 1411 // have been elided. G1, like CMS, allows this, but should be 1412 // ready to provide a compensating write barrier as necessary 1413 // if that storage came out of a non-young region. The efficiency 1414 // of this implementation depends crucially on being able to 1415 // answer very efficiently in constant time whether a piece of 1416 // storage in the heap comes from a young region or not. 1417 // See ReduceInitialCardMarks. 1418 virtual bool can_elide_tlab_store_barriers() const { 1419 return true; 1420 } 1421 1422 virtual bool card_mark_must_follow_store() const { 1423 return true; 1424 } 1425 1426 inline bool is_in_young(const oop obj); 1427 1428 #ifdef ASSERT 1429 virtual bool is_in_partial_collection(const void* p); 1430 #endif 1431 1432 virtual bool is_scavengable(const void* addr); 1433 1434 // We don't need barriers for initializing stores to objects 1435 // in the young gen: for the SATB pre-barrier, there is no 1436 // pre-value that needs to be remembered; for the remembered-set 1437 // update logging post-barrier, we don't maintain remembered set 1438 // information for young gen objects. 1439 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1440 1441 // Returns "true" iff the given word_size is "very large". 1442 static bool isHumongous(size_t word_size) { 1443 // Note this has to be strictly greater-than as the TLABs 1444 // are capped at the humongous thresold and we want to 1445 // ensure that we don't try to allocate a TLAB as 1446 // humongous and that we don't allocate a humongous 1447 // object in a TLAB. 1448 return word_size > _humongous_object_threshold_in_words; 1449 } 1450 1451 // Update mod union table with the set of dirty cards. 1452 void updateModUnion(); 1453 1454 // Set the mod union bits corresponding to the given memRegion. Note 1455 // that this is always a safe operation, since it doesn't clear any 1456 // bits. 1457 void markModUnionRange(MemRegion mr); 1458 1459 // Records the fact that a marking phase is no longer in progress. 1460 void set_marking_complete() { 1461 _mark_in_progress = false; 1462 } 1463 void set_marking_started() { 1464 _mark_in_progress = true; 1465 } 1466 bool mark_in_progress() { 1467 return _mark_in_progress; 1468 } 1469 1470 // Print the maximum heap capacity. 1471 virtual size_t max_capacity() const; 1472 1473 virtual jlong millis_since_last_gc(); 1474 1475 1476 // Convenience function to be used in situations where the heap type can be 1477 // asserted to be this type. 1478 static G1CollectedHeap* heap(); 1479 1480 void set_region_short_lived_locked(HeapRegion* hr); 1481 // add appropriate methods for any other surv rate groups 1482 1483 YoungList* young_list() const { return _young_list; } 1484 1485 // debugging 1486 bool check_young_list_well_formed() { 1487 return _young_list->check_list_well_formed(); 1488 } 1489 1490 bool check_young_list_empty(bool check_heap, 1491 bool check_sample = true); 1492 1493 // *** Stuff related to concurrent marking. It's not clear to me that so 1494 // many of these need to be public. 1495 1496 // The functions below are helper functions that a subclass of 1497 // "CollectedHeap" can use in the implementation of its virtual 1498 // functions. 1499 // This performs a concurrent marking of the live objects in a 1500 // bitmap off to the side. 1501 void doConcurrentMark(); 1502 1503 bool isMarkedPrev(oop obj) const; 1504 bool isMarkedNext(oop obj) const; 1505 1506 // Determine if an object is dead, given the object and also 1507 // the region to which the object belongs. An object is dead 1508 // iff a) it was not allocated since the last mark and b) it 1509 // is not marked. 1510 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1511 return 1512 !hr->obj_allocated_since_prev_marking(obj) && 1513 !isMarkedPrev(obj); 1514 } 1515 1516 // This function returns true when an object has been 1517 // around since the previous marking and hasn't yet 1518 // been marked during this marking. 1519 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1520 return 1521 !hr->obj_allocated_since_next_marking(obj) && 1522 !isMarkedNext(obj); 1523 } 1524 1525 // Determine if an object is dead, given only the object itself. 1526 // This will find the region to which the object belongs and 1527 // then call the region version of the same function. 1528 1529 // Added if it is NULL it isn't dead. 1530 1531 inline bool is_obj_dead(const oop obj) const; 1532 1533 inline bool is_obj_ill(const oop obj) const; 1534 1535 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1536 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1537 bool is_marked(oop obj, VerifyOption vo); 1538 const char* top_at_mark_start_str(VerifyOption vo); 1539 1540 ConcurrentMark* concurrent_mark() const { return _cm; } 1541 1542 // Refinement 1543 1544 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1545 1546 // The dirty cards region list is used to record a subset of regions 1547 // whose cards need clearing. The list if populated during the 1548 // remembered set scanning and drained during the card table 1549 // cleanup. Although the methods are reentrant, population/draining 1550 // phases must not overlap. For synchronization purposes the last 1551 // element on the list points to itself. 1552 HeapRegion* _dirty_cards_region_list; 1553 void push_dirty_cards_region(HeapRegion* hr); 1554 HeapRegion* pop_dirty_cards_region(); 1555 1556 // Optimized nmethod scanning support routines 1557 1558 // Register the given nmethod with the G1 heap 1559 virtual void register_nmethod(nmethod* nm); 1560 1561 // Unregister the given nmethod from the G1 heap 1562 virtual void unregister_nmethod(nmethod* nm); 1563 1564 // Free up superfluous code root memory. 1565 void purge_code_root_memory(); 1566 1567 // Rebuild the stong code root lists for each region 1568 // after a full GC 1569 void rebuild_strong_code_roots(); 1570 1571 // Delete entries for dead interned string and clean up unreferenced symbols 1572 // in symbol table, possibly in parallel. 1573 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1574 1575 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1576 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1577 1578 // Redirty logged cards in the refinement queue. 1579 void redirty_logged_cards(); 1580 // Verification 1581 1582 // The following is just to alert the verification code 1583 // that a full collection has occurred and that the 1584 // remembered sets are no longer up to date. 1585 bool _full_collection; 1586 void set_full_collection() { _full_collection = true;} 1587 void clear_full_collection() {_full_collection = false;} 1588 bool full_collection() {return _full_collection;} 1589 1590 // Perform any cleanup actions necessary before allowing a verification. 1591 virtual void prepare_for_verify(); 1592 1593 // Perform verification. 1594 1595 // vo == UsePrevMarking -> use "prev" marking information, 1596 // vo == UseNextMarking -> use "next" marking information 1597 // vo == UseMarkWord -> use the mark word in the object header 1598 // 1599 // NOTE: Only the "prev" marking information is guaranteed to be 1600 // consistent most of the time, so most calls to this should use 1601 // vo == UsePrevMarking. 1602 // Currently, there is only one case where this is called with 1603 // vo == UseNextMarking, which is to verify the "next" marking 1604 // information at the end of remark. 1605 // Currently there is only one place where this is called with 1606 // vo == UseMarkWord, which is to verify the marking during a 1607 // full GC. 1608 void verify(bool silent, VerifyOption vo); 1609 1610 // Override; it uses the "prev" marking information 1611 virtual void verify(bool silent); 1612 1613 // The methods below are here for convenience and dispatch the 1614 // appropriate method depending on value of the given VerifyOption 1615 // parameter. The values for that parameter, and their meanings, 1616 // are the same as those above. 1617 1618 bool is_obj_dead_cond(const oop obj, 1619 const HeapRegion* hr, 1620 const VerifyOption vo) const; 1621 1622 bool is_obj_dead_cond(const oop obj, 1623 const VerifyOption vo) const; 1624 1625 // Printing 1626 1627 virtual void print_on(outputStream* st) const; 1628 virtual void print_extended_on(outputStream* st) const; 1629 virtual void print_on_error(outputStream* st) const; 1630 1631 virtual void print_gc_threads_on(outputStream* st) const; 1632 virtual void gc_threads_do(ThreadClosure* tc) const; 1633 1634 // Override 1635 void print_tracing_info() const; 1636 1637 // The following two methods are helpful for debugging RSet issues. 1638 void print_cset_rsets() PRODUCT_RETURN; 1639 void print_all_rsets() PRODUCT_RETURN; 1640 1641 public: 1642 size_t pending_card_num(); 1643 size_t cards_scanned(); 1644 1645 protected: 1646 size_t _max_heap_capacity; 1647 }; 1648 1649 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP