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_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 void trace_heap(GCWhen::Type when, GCTracer* tracer); 379 380 double verify(bool guard, const char* msg); 381 void verify_before_gc(); 382 void verify_after_gc(); 383 384 void log_gc_header(); 385 void log_gc_footer(double pause_time_sec); 386 387 // These are macros so that, if the assert fires, we get the correct 388 // line number, file, etc. 389 390 #define heap_locking_asserts_err_msg(_extra_message_) \ 391 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 392 (_extra_message_), \ 393 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 394 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 395 BOOL_TO_STR(Thread::current()->is_VM_thread())) 396 397 #define assert_heap_locked() \ 398 do { \ 399 assert(Heap_lock->owned_by_self(), \ 400 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 401 } while (0) 402 403 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 404 do { \ 405 assert(Heap_lock->owned_by_self() || \ 406 (SafepointSynchronize::is_at_safepoint() && \ 407 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 408 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 409 "should be at a safepoint")); \ 410 } while (0) 411 412 #define assert_heap_locked_and_not_at_safepoint() \ 413 do { \ 414 assert(Heap_lock->owned_by_self() && \ 415 !SafepointSynchronize::is_at_safepoint(), \ 416 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 417 "should not be at a safepoint")); \ 418 } while (0) 419 420 #define assert_heap_not_locked() \ 421 do { \ 422 assert(!Heap_lock->owned_by_self(), \ 423 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 424 } while (0) 425 426 #define assert_heap_not_locked_and_not_at_safepoint() \ 427 do { \ 428 assert(!Heap_lock->owned_by_self() && \ 429 !SafepointSynchronize::is_at_safepoint(), \ 430 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 431 "should not be at a safepoint")); \ 432 } while (0) 433 434 #define assert_at_safepoint(_should_be_vm_thread_) \ 435 do { \ 436 assert(SafepointSynchronize::is_at_safepoint() && \ 437 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 438 heap_locking_asserts_err_msg("should be at a safepoint")); \ 439 } while (0) 440 441 #define assert_not_at_safepoint() \ 442 do { \ 443 assert(!SafepointSynchronize::is_at_safepoint(), \ 444 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 445 } while (0) 446 447 protected: 448 449 // The young region list. 450 YoungList* _young_list; 451 452 // The current policy object for the collector. 453 G1CollectorPolicy* _g1_policy; 454 455 // This is the second level of trying to allocate a new region. If 456 // new_region() didn't find a region on the free_list, this call will 457 // check whether there's anything available on the 458 // secondary_free_list and/or wait for more regions to appear on 459 // that list, if _free_regions_coming is set. 460 HeapRegion* new_region_try_secondary_free_list(bool is_old); 461 462 // Try to allocate a single non-humongous HeapRegion sufficient for 463 // an allocation of the given word_size. If do_expand is true, 464 // attempt to expand the heap if necessary to satisfy the allocation 465 // request. If the region is to be used as an old region or for a 466 // humongous object, set is_old to true. If not, to false. 467 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 468 469 // Initialize a contiguous set of free regions of length num_regions 470 // and starting at index first so that they appear as a single 471 // humongous region. 472 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 473 uint num_regions, 474 size_t word_size, 475 AllocationContext_t context); 476 477 // Attempt to allocate a humongous object of the given size. Return 478 // NULL if unsuccessful. 479 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 480 481 // The following two methods, allocate_new_tlab() and 482 // mem_allocate(), are the two main entry points from the runtime 483 // into the G1's allocation routines. They have the following 484 // assumptions: 485 // 486 // * They should both be called outside safepoints. 487 // 488 // * They should both be called without holding the Heap_lock. 489 // 490 // * All allocation requests for new TLABs should go to 491 // allocate_new_tlab(). 492 // 493 // * All non-TLAB allocation requests should go to mem_allocate(). 494 // 495 // * If either call cannot satisfy the allocation request using the 496 // current allocating region, they will try to get a new one. If 497 // this fails, they will attempt to do an evacuation pause and 498 // retry the allocation. 499 // 500 // * If all allocation attempts fail, even after trying to schedule 501 // an evacuation pause, allocate_new_tlab() will return NULL, 502 // whereas mem_allocate() will attempt a heap expansion and/or 503 // schedule a Full GC. 504 // 505 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 506 // should never be called with word_size being humongous. All 507 // humongous allocation requests should go to mem_allocate() which 508 // will satisfy them with a special path. 509 510 virtual HeapWord* allocate_new_tlab(size_t word_size); 511 512 virtual HeapWord* mem_allocate(size_t word_size, 513 bool* gc_overhead_limit_was_exceeded); 514 515 // The following three methods take a gc_count_before_ret 516 // parameter which is used to return the GC count if the method 517 // returns NULL. Given that we are required to read the GC count 518 // while holding the Heap_lock, and these paths will take the 519 // Heap_lock at some point, it's easier to get them to read the GC 520 // count while holding the Heap_lock before they return NULL instead 521 // of the caller (namely: mem_allocate()) having to also take the 522 // Heap_lock just to read the GC count. 523 524 // First-level mutator allocation attempt: try to allocate out of 525 // the mutator alloc region without taking the Heap_lock. This 526 // should only be used for non-humongous allocations. 527 inline HeapWord* attempt_allocation(size_t word_size, 528 uint* gc_count_before_ret, 529 uint* gclocker_retry_count_ret); 530 531 // Second-level mutator allocation attempt: take the Heap_lock and 532 // retry the allocation attempt, potentially scheduling a GC 533 // pause. This should only be used for non-humongous allocations. 534 HeapWord* attempt_allocation_slow(size_t word_size, 535 AllocationContext_t context, 536 uint* gc_count_before_ret, 537 uint* gclocker_retry_count_ret); 538 539 // Takes the Heap_lock and attempts a humongous allocation. It can 540 // potentially schedule a GC pause. 541 HeapWord* attempt_allocation_humongous(size_t word_size, 542 uint* gc_count_before_ret, 543 uint* gclocker_retry_count_ret); 544 545 // Allocation attempt that should be called during safepoints (e.g., 546 // at the end of a successful GC). expect_null_mutator_alloc_region 547 // specifies whether the mutator alloc region is expected to be NULL 548 // or not. 549 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 550 AllocationContext_t context, 551 bool expect_null_mutator_alloc_region); 552 553 // It dirties the cards that cover the block so that so that the post 554 // write barrier never queues anything when updating objects on this 555 // block. It is assumed (and in fact we assert) that the block 556 // belongs to a young region. 557 inline void dirty_young_block(HeapWord* start, size_t word_size); 558 559 // Allocate blocks during garbage collection. Will ensure an 560 // allocation region, either by picking one or expanding the 561 // heap, and then allocate a block of the given size. The block 562 // may not be a humongous - it must fit into a single heap region. 563 inline HeapWord* par_allocate_during_gc(InCSetState dest, 564 size_t word_size, 565 AllocationContext_t context); 566 // Ensure that no further allocations can happen in "r", bearing in mind 567 // that parallel threads might be attempting allocations. 568 void par_allocate_remaining_space(HeapRegion* r); 569 570 // Allocation attempt during GC for a survivor object / PLAB. 571 inline HeapWord* survivor_attempt_allocation(size_t word_size, 572 AllocationContext_t context); 573 574 // Allocation attempt during GC for an old object / PLAB. 575 inline HeapWord* old_attempt_allocation(size_t word_size, 576 AllocationContext_t context); 577 578 // These methods are the "callbacks" from the G1AllocRegion class. 579 580 // For mutator alloc regions. 581 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 582 void retire_mutator_alloc_region(HeapRegion* alloc_region, 583 size_t allocated_bytes); 584 585 // For GC alloc regions. 586 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 587 InCSetState dest); 588 void retire_gc_alloc_region(HeapRegion* alloc_region, 589 size_t allocated_bytes, InCSetState dest); 590 591 // - if explicit_gc is true, the GC is for a System.gc() or a heap 592 // inspection request and should collect the entire heap 593 // - if clear_all_soft_refs is true, all soft references should be 594 // cleared during the GC 595 // - if explicit_gc is false, word_size describes the allocation that 596 // the GC should attempt (at least) to satisfy 597 // - it returns false if it is unable to do the collection due to the 598 // GC locker being active, true otherwise 599 bool do_collection(bool explicit_gc, 600 bool clear_all_soft_refs, 601 size_t word_size); 602 603 // Callback from VM_G1CollectFull operation. 604 // Perform a full collection. 605 virtual void do_full_collection(bool clear_all_soft_refs); 606 607 // Resize the heap if necessary after a full collection. If this is 608 // after a collect-for allocation, "word_size" is the allocation size, 609 // and will be considered part of the used portion of the heap. 610 void resize_if_necessary_after_full_collection(size_t word_size); 611 612 // Callback from VM_G1CollectForAllocation operation. 613 // This function does everything necessary/possible to satisfy a 614 // failed allocation request (including collection, expansion, etc.) 615 HeapWord* satisfy_failed_allocation(size_t word_size, 616 AllocationContext_t context, 617 bool* succeeded); 618 619 // Attempting to expand the heap sufficiently 620 // to support an allocation of the given "word_size". If 621 // successful, perform the allocation and return the address of the 622 // allocated block, or else "NULL". 623 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 624 625 // Process any reference objects discovered during 626 // an incremental evacuation pause. 627 void process_discovered_references(uint no_of_gc_workers); 628 629 // Enqueue any remaining discovered references 630 // after processing. 631 void enqueue_discovered_references(uint no_of_gc_workers); 632 633 public: 634 635 G1Allocator* allocator() { 636 return _allocator; 637 } 638 639 G1MonitoringSupport* g1mm() { 640 assert(_g1mm != NULL, "should have been initialized"); 641 return _g1mm; 642 } 643 644 // Expand the garbage-first heap by at least the given size (in bytes!). 645 // Returns true if the heap was expanded by the requested amount; 646 // false otherwise. 647 // (Rounds up to a HeapRegion boundary.) 648 bool expand(size_t expand_bytes); 649 650 // Returns the PLAB statistics for a given destination. 651 inline PLABStats* alloc_buffer_stats(InCSetState dest); 652 653 // Determines PLAB size for a given destination. 654 inline size_t desired_plab_sz(InCSetState dest); 655 656 inline AllocationContextStats& allocation_context_stats(); 657 658 // Do anything common to GC's. 659 virtual void gc_prologue(bool full); 660 virtual void gc_epilogue(bool full); 661 662 // Modify the reclaim candidate set and test for presence. 663 // These are only valid for starts_humongous regions. 664 inline void set_humongous_reclaim_candidate(uint region, bool value); 665 inline bool is_humongous_reclaim_candidate(uint region); 666 667 // Remove from the reclaim candidate set. Also remove from the 668 // collection set so that later encounters avoid the slow path. 669 inline void set_humongous_is_live(oop obj); 670 671 // Register the given region to be part of the collection set. 672 inline void register_humongous_region_with_in_cset_fast_test(uint index); 673 // Register regions with humongous objects (actually on the start region) in 674 // the in_cset_fast_test table. 675 void register_humongous_regions_with_in_cset_fast_test(); 676 // We register a region with the fast "in collection set" test. We 677 // simply set to true the array slot corresponding to this region. 678 void register_young_region_with_in_cset_fast_test(HeapRegion* r) { 679 _in_cset_fast_test.set_in_young(r->hrm_index()); 680 } 681 void register_old_region_with_in_cset_fast_test(HeapRegion* r) { 682 _in_cset_fast_test.set_in_old(r->hrm_index()); 683 } 684 685 // This is a fast test on whether a reference points into the 686 // collection set or not. Assume that the reference 687 // points into the heap. 688 inline bool in_cset_fast_test(oop obj); 689 690 void clear_cset_fast_test() { 691 _in_cset_fast_test.clear(); 692 } 693 694 // This is called at the start of either a concurrent cycle or a Full 695 // GC to update the number of old marking cycles started. 696 void increment_old_marking_cycles_started(); 697 698 // This is called at the end of either a concurrent cycle or a Full 699 // GC to update the number of old marking cycles completed. Those two 700 // can happen in a nested fashion, i.e., we start a concurrent 701 // cycle, a Full GC happens half-way through it which ends first, 702 // and then the cycle notices that a Full GC happened and ends 703 // too. The concurrent parameter is a boolean to help us do a bit 704 // tighter consistency checking in the method. If concurrent is 705 // false, the caller is the inner caller in the nesting (i.e., the 706 // Full GC). If concurrent is true, the caller is the outer caller 707 // in this nesting (i.e., the concurrent cycle). Further nesting is 708 // not currently supported. The end of this call also notifies 709 // the FullGCCount_lock in case a Java thread is waiting for a full 710 // GC to happen (e.g., it called System.gc() with 711 // +ExplicitGCInvokesConcurrent). 712 void increment_old_marking_cycles_completed(bool concurrent); 713 714 uint old_marking_cycles_completed() { 715 return _old_marking_cycles_completed; 716 } 717 718 void register_concurrent_cycle_start(const Ticks& start_time); 719 void register_concurrent_cycle_end(); 720 void trace_heap_after_concurrent_cycle(); 721 722 G1YCType yc_type(); 723 724 G1HRPrinter* hr_printer() { return &_hr_printer; } 725 726 // Frees a non-humongous region by initializing its contents and 727 // adding it to the free list that's passed as a parameter (this is 728 // usually a local list which will be appended to the master free 729 // list later). The used bytes of freed regions are accumulated in 730 // pre_used. If par is true, the region's RSet will not be freed 731 // up. The assumption is that this will be done later. 732 // The locked parameter indicates if the caller has already taken 733 // care of proper synchronization. This may allow some optimizations. 734 void free_region(HeapRegion* hr, 735 FreeRegionList* free_list, 736 bool par, 737 bool locked = false); 738 739 // Frees a humongous region by collapsing it into individual regions 740 // and calling free_region() for each of them. The freed regions 741 // will be added to the free list that's passed as a parameter (this 742 // is usually a local list which will be appended to the master free 743 // list later). The used bytes of freed regions are accumulated in 744 // pre_used. If par is true, the region's RSet will not be freed 745 // up. The assumption is that this will be done later. 746 void free_humongous_region(HeapRegion* hr, 747 FreeRegionList* free_list, 748 bool par); 749 protected: 750 751 // Shrink the garbage-first heap by at most the given size (in bytes!). 752 // (Rounds down to a HeapRegion boundary.) 753 virtual void shrink(size_t expand_bytes); 754 void shrink_helper(size_t expand_bytes); 755 756 #if TASKQUEUE_STATS 757 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 758 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 759 void reset_taskqueue_stats(); 760 #endif // TASKQUEUE_STATS 761 762 // Schedule the VM operation that will do an evacuation pause to 763 // satisfy an allocation request of word_size. *succeeded will 764 // return whether the VM operation was successful (it did do an 765 // evacuation pause) or not (another thread beat us to it or the GC 766 // locker was active). Given that we should not be holding the 767 // Heap_lock when we enter this method, we will pass the 768 // gc_count_before (i.e., total_collections()) as a parameter since 769 // it has to be read while holding the Heap_lock. Currently, both 770 // methods that call do_collection_pause() release the Heap_lock 771 // before the call, so it's easy to read gc_count_before just before. 772 HeapWord* do_collection_pause(size_t word_size, 773 uint gc_count_before, 774 bool* succeeded, 775 GCCause::Cause gc_cause); 776 777 // The guts of the incremental collection pause, executed by the vm 778 // thread. It returns false if it is unable to do the collection due 779 // to the GC locker being active, true otherwise 780 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 781 782 // Actually do the work of evacuating the collection set. 783 void evacuate_collection_set(EvacuationInfo& evacuation_info); 784 785 // The g1 remembered set of the heap. 786 G1RemSet* _g1_rem_set; 787 788 // A set of cards that cover the objects for which the Rsets should be updated 789 // concurrently after the collection. 790 DirtyCardQueueSet _dirty_card_queue_set; 791 792 // The closure used to refine a single card. 793 RefineCardTableEntryClosure* _refine_cte_cl; 794 795 // A function to check the consistency of dirty card logs. 796 void check_ct_logs_at_safepoint(); 797 798 // A DirtyCardQueueSet that is used to hold cards that contain 799 // references into the current collection set. This is used to 800 // update the remembered sets of the regions in the collection 801 // set in the event of an evacuation failure. 802 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 803 804 // After a collection pause, make the regions in the CS into free 805 // regions. 806 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 807 808 // Abandon the current collection set without recording policy 809 // statistics or updating free lists. 810 void abandon_collection_set(HeapRegion* cs_head); 811 812 // The concurrent marker (and the thread it runs in.) 813 ConcurrentMark* _cm; 814 ConcurrentMarkThread* _cmThread; 815 bool _mark_in_progress; 816 817 // The concurrent refiner. 818 ConcurrentG1Refine* _cg1r; 819 820 // The parallel task queues 821 RefToScanQueueSet *_task_queues; 822 823 // True iff a evacuation has failed in the current collection. 824 bool _evacuation_failed; 825 826 EvacuationFailedInfo* _evacuation_failed_info_array; 827 828 // Failed evacuations cause some logical from-space objects to have 829 // forwarding pointers to themselves. Reset them. 830 void remove_self_forwarding_pointers(); 831 832 // Together, these store an object with a preserved mark, and its mark value. 833 Stack<oop, mtGC> _objs_with_preserved_marks; 834 Stack<markOop, mtGC> _preserved_marks_of_objs; 835 836 // Preserve the mark of "obj", if necessary, in preparation for its mark 837 // word being overwritten with a self-forwarding-pointer. 838 void preserve_mark_if_necessary(oop obj, markOop m); 839 840 // The stack of evac-failure objects left to be scanned. 841 GrowableArray<oop>* _evac_failure_scan_stack; 842 // The closure to apply to evac-failure objects. 843 844 OopsInHeapRegionClosure* _evac_failure_closure; 845 // Set the field above. 846 void 847 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 848 _evac_failure_closure = evac_failure_closure; 849 } 850 851 // Push "obj" on the scan stack. 852 void push_on_evac_failure_scan_stack(oop obj); 853 // Process scan stack entries until the stack is empty. 854 void drain_evac_failure_scan_stack(); 855 // True iff an invocation of "drain_scan_stack" is in progress; to 856 // prevent unnecessary recursion. 857 bool _drain_in_progress; 858 859 // Do any necessary initialization for evacuation-failure handling. 860 // "cl" is the closure that will be used to process evac-failure 861 // objects. 862 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 863 // Do any necessary cleanup for evacuation-failure handling data 864 // structures. 865 void finalize_for_evac_failure(); 866 867 // An attempt to evacuate "obj" has failed; take necessary steps. 868 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 869 void handle_evacuation_failure_common(oop obj, markOop m); 870 871 #ifndef PRODUCT 872 // Support for forcing evacuation failures. Analogous to 873 // PromotionFailureALot for the other collectors. 874 875 // Records whether G1EvacuationFailureALot should be in effect 876 // for the current GC 877 bool _evacuation_failure_alot_for_current_gc; 878 879 // Used to record the GC number for interval checking when 880 // determining whether G1EvaucationFailureALot is in effect 881 // for the current GC. 882 size_t _evacuation_failure_alot_gc_number; 883 884 // Count of the number of evacuations between failures. 885 volatile size_t _evacuation_failure_alot_count; 886 887 // Set whether G1EvacuationFailureALot should be in effect 888 // for the current GC (based upon the type of GC and which 889 // command line flags are set); 890 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 891 bool during_initial_mark, 892 bool during_marking); 893 894 inline void set_evacuation_failure_alot_for_current_gc(); 895 896 // Return true if it's time to cause an evacuation failure. 897 inline bool evacuation_should_fail(); 898 899 // Reset the G1EvacuationFailureALot counters. Should be called at 900 // the end of an evacuation pause in which an evacuation failure occurred. 901 inline void reset_evacuation_should_fail(); 902 #endif // !PRODUCT 903 904 // ("Weak") Reference processing support. 905 // 906 // G1 has 2 instances of the reference processor class. One 907 // (_ref_processor_cm) handles reference object discovery 908 // and subsequent processing during concurrent marking cycles. 909 // 910 // The other (_ref_processor_stw) handles reference object 911 // discovery and processing during full GCs and incremental 912 // evacuation pauses. 913 // 914 // During an incremental pause, reference discovery will be 915 // temporarily disabled for _ref_processor_cm and will be 916 // enabled for _ref_processor_stw. At the end of the evacuation 917 // pause references discovered by _ref_processor_stw will be 918 // processed and discovery will be disabled. The previous 919 // setting for reference object discovery for _ref_processor_cm 920 // will be re-instated. 921 // 922 // At the start of marking: 923 // * Discovery by the CM ref processor is verified to be inactive 924 // and it's discovered lists are empty. 925 // * Discovery by the CM ref processor is then enabled. 926 // 927 // At the end of marking: 928 // * Any references on the CM ref processor's discovered 929 // lists are processed (possibly MT). 930 // 931 // At the start of full GC we: 932 // * Disable discovery by the CM ref processor and 933 // empty CM ref processor's discovered lists 934 // (without processing any entries). 935 // * Verify that the STW ref processor is inactive and it's 936 // discovered lists are empty. 937 // * Temporarily set STW ref processor discovery as single threaded. 938 // * Temporarily clear the STW ref processor's _is_alive_non_header 939 // field. 940 // * Finally enable discovery by the STW ref processor. 941 // 942 // The STW ref processor is used to record any discovered 943 // references during the full GC. 944 // 945 // At the end of a full GC we: 946 // * Enqueue any reference objects discovered by the STW ref processor 947 // that have non-live referents. This has the side-effect of 948 // making the STW ref processor inactive by disabling discovery. 949 // * Verify that the CM ref processor is still inactive 950 // and no references have been placed on it's discovered 951 // lists (also checked as a precondition during initial marking). 952 953 // The (stw) reference processor... 954 ReferenceProcessor* _ref_processor_stw; 955 956 STWGCTimer* _gc_timer_stw; 957 ConcurrentGCTimer* _gc_timer_cm; 958 959 G1OldTracer* _gc_tracer_cm; 960 G1NewTracer* _gc_tracer_stw; 961 962 // During reference object discovery, the _is_alive_non_header 963 // closure (if non-null) is applied to the referent object to 964 // determine whether the referent is live. If so then the 965 // reference object does not need to be 'discovered' and can 966 // be treated as a regular oop. This has the benefit of reducing 967 // the number of 'discovered' reference objects that need to 968 // be processed. 969 // 970 // Instance of the is_alive closure for embedding into the 971 // STW reference processor as the _is_alive_non_header field. 972 // Supplying a value for the _is_alive_non_header field is 973 // optional but doing so prevents unnecessary additions to 974 // the discovered lists during reference discovery. 975 G1STWIsAliveClosure _is_alive_closure_stw; 976 977 // The (concurrent marking) reference processor... 978 ReferenceProcessor* _ref_processor_cm; 979 980 // Instance of the concurrent mark is_alive closure for embedding 981 // into the Concurrent Marking reference processor as the 982 // _is_alive_non_header field. Supplying a value for the 983 // _is_alive_non_header field is optional but doing so prevents 984 // unnecessary additions to the discovered lists during reference 985 // discovery. 986 G1CMIsAliveClosure _is_alive_closure_cm; 987 988 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 989 HeapRegion** _worker_cset_start_region; 990 991 // Time stamp to validate the regions recorded in the cache 992 // used by G1CollectedHeap::start_cset_region_for_worker(). 993 // The heap region entry for a given worker is valid iff 994 // the associated time stamp value matches the current value 995 // of G1CollectedHeap::_gc_time_stamp. 996 uint* _worker_cset_start_region_time_stamp; 997 998 volatile bool _free_regions_coming; 999 1000 public: 1001 1002 void set_refine_cte_cl_concurrency(bool concurrent); 1003 1004 RefToScanQueue *task_queue(int i) const; 1005 1006 // A set of cards where updates happened during the GC 1007 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1008 1009 // A DirtyCardQueueSet that is used to hold cards that contain 1010 // references into the current collection set. This is used to 1011 // update the remembered sets of the regions in the collection 1012 // set in the event of an evacuation failure. 1013 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1014 { return _into_cset_dirty_card_queue_set; } 1015 1016 // Create a G1CollectedHeap with the specified policy. 1017 // Must call the initialize method afterwards. 1018 // May not return if something goes wrong. 1019 G1CollectedHeap(G1CollectorPolicy* policy); 1020 1021 // Initialize the G1CollectedHeap to have the initial and 1022 // maximum sizes and remembered and barrier sets 1023 // specified by the policy object. 1024 jint initialize(); 1025 1026 virtual void stop(); 1027 1028 // Return the (conservative) maximum heap alignment for any G1 heap 1029 static size_t conservative_max_heap_alignment(); 1030 1031 // Initialize weak reference processing. 1032 virtual void ref_processing_init(); 1033 1034 // Explicitly import set_par_threads into this scope 1035 using SharedHeap::set_par_threads; 1036 // Set _n_par_threads according to a policy TBD. 1037 void set_par_threads(); 1038 1039 virtual CollectedHeap::Name kind() const { 1040 return CollectedHeap::G1CollectedHeap; 1041 } 1042 1043 // The current policy object for the collector. 1044 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1045 1046 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1047 1048 // Adaptive size policy. No such thing for g1. 1049 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1050 1051 // The rem set and barrier set. 1052 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1053 1054 unsigned get_gc_time_stamp() { 1055 return _gc_time_stamp; 1056 } 1057 1058 inline void reset_gc_time_stamp(); 1059 1060 void check_gc_time_stamps() PRODUCT_RETURN; 1061 1062 inline void increment_gc_time_stamp(); 1063 1064 // Reset the given region's GC timestamp. If it's starts humongous, 1065 // also reset the GC timestamp of its corresponding 1066 // continues humongous regions too. 1067 void reset_gc_time_stamps(HeapRegion* hr); 1068 1069 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1070 DirtyCardQueue* into_cset_dcq, 1071 bool concurrent, uint worker_i); 1072 1073 // The shared block offset table array. 1074 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1075 1076 // Reference Processing accessors 1077 1078 // The STW reference processor.... 1079 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1080 1081 // The Concurrent Marking reference processor... 1082 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1083 1084 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1085 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1086 1087 virtual size_t capacity() const; 1088 virtual size_t used() const; 1089 // This should be called when we're not holding the heap lock. The 1090 // result might be a bit inaccurate. 1091 size_t used_unlocked() const; 1092 size_t recalculate_used() const; 1093 1094 // These virtual functions do the actual allocation. 1095 // Some heaps may offer a contiguous region for shared non-blocking 1096 // allocation, via inlined code (by exporting the address of the top and 1097 // end fields defining the extent of the contiguous allocation region.) 1098 // But G1CollectedHeap doesn't yet support this. 1099 1100 virtual bool is_maximal_no_gc() const { 1101 return _hrm.available() == 0; 1102 } 1103 1104 // The current number of regions in the heap. 1105 uint num_regions() const { return _hrm.length(); } 1106 1107 // The max number of regions in the heap. 1108 uint max_regions() const { return _hrm.max_length(); } 1109 1110 // The number of regions that are completely free. 1111 uint num_free_regions() const { return _hrm.num_free_regions(); } 1112 1113 MemoryUsage get_auxiliary_data_memory_usage() const { 1114 return _hrm.get_auxiliary_data_memory_usage(); 1115 } 1116 1117 // The number of regions that are not completely free. 1118 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1119 1120 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1121 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1122 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1123 void verify_dirty_young_regions() PRODUCT_RETURN; 1124 1125 #ifndef PRODUCT 1126 // Make sure that the given bitmap has no marked objects in the 1127 // range [from,limit). If it does, print an error message and return 1128 // false. Otherwise, just return true. bitmap_name should be "prev" 1129 // or "next". 1130 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1131 HeapWord* from, HeapWord* limit); 1132 1133 // Verify that the prev / next bitmap range [tams,end) for the given 1134 // region has no marks. Return true if all is well, false if errors 1135 // are detected. 1136 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1137 #endif // PRODUCT 1138 1139 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1140 // the given region do not have any spurious marks. If errors are 1141 // detected, print appropriate error messages and crash. 1142 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1143 1144 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1145 // have any spurious marks. If errors are detected, print 1146 // appropriate error messages and crash. 1147 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1148 1149 // Do sanity check on the contents of the in-cset fast test table. 1150 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1151 1152 // verify_region_sets() performs verification over the region 1153 // lists. It will be compiled in the product code to be used when 1154 // necessary (i.e., during heap verification). 1155 void verify_region_sets(); 1156 1157 // verify_region_sets_optional() is planted in the code for 1158 // list verification in non-product builds (and it can be enabled in 1159 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1160 #if HEAP_REGION_SET_FORCE_VERIFY 1161 void verify_region_sets_optional() { 1162 verify_region_sets(); 1163 } 1164 #else // HEAP_REGION_SET_FORCE_VERIFY 1165 void verify_region_sets_optional() { } 1166 #endif // HEAP_REGION_SET_FORCE_VERIFY 1167 1168 #ifdef ASSERT 1169 bool is_on_master_free_list(HeapRegion* hr) { 1170 return _hrm.is_free(hr); 1171 } 1172 #endif // ASSERT 1173 1174 // Wrapper for the region list operations that can be called from 1175 // methods outside this class. 1176 1177 void secondary_free_list_add(FreeRegionList* list) { 1178 _secondary_free_list.add_ordered(list); 1179 } 1180 1181 void append_secondary_free_list() { 1182 _hrm.insert_list_into_free_list(&_secondary_free_list); 1183 } 1184 1185 void append_secondary_free_list_if_not_empty_with_lock() { 1186 // If the secondary free list looks empty there's no reason to 1187 // take the lock and then try to append it. 1188 if (!_secondary_free_list.is_empty()) { 1189 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1190 append_secondary_free_list(); 1191 } 1192 } 1193 1194 inline void old_set_remove(HeapRegion* hr); 1195 1196 size_t non_young_capacity_bytes() { 1197 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1198 } 1199 1200 void set_free_regions_coming(); 1201 void reset_free_regions_coming(); 1202 bool free_regions_coming() { return _free_regions_coming; } 1203 void wait_while_free_regions_coming(); 1204 1205 // Determine whether the given region is one that we are using as an 1206 // old GC alloc region. 1207 bool is_old_gc_alloc_region(HeapRegion* hr) { 1208 return _allocator->is_retained_old_region(hr); 1209 } 1210 1211 // Perform a collection of the heap; intended for use in implementing 1212 // "System.gc". This probably implies as full a collection as the 1213 // "CollectedHeap" supports. 1214 virtual void collect(GCCause::Cause cause); 1215 1216 // The same as above but assume that the caller holds the Heap_lock. 1217 void collect_locked(GCCause::Cause cause); 1218 1219 virtual bool copy_allocation_context_stats(const jint* contexts, 1220 jlong* totals, 1221 jbyte* accuracy, 1222 jint len); 1223 1224 // True iff an evacuation has failed in the most-recent collection. 1225 bool evacuation_failed() { return _evacuation_failed; } 1226 1227 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1228 void prepend_to_freelist(FreeRegionList* list); 1229 void decrement_summary_bytes(size_t bytes); 1230 1231 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1232 virtual bool is_in(const void* p) const; 1233 #ifdef ASSERT 1234 // Returns whether p is in one of the available areas of the heap. Slow but 1235 // extensive version. 1236 bool is_in_exact(const void* p) const; 1237 #endif 1238 1239 // Return "TRUE" iff the given object address is within the collection 1240 // set. Slow implementation. 1241 inline bool obj_in_cs(oop obj); 1242 1243 inline bool is_in_cset(oop obj); 1244 1245 inline bool is_in_cset_or_humongous(const oop obj); 1246 1247 private: 1248 // This array is used for a quick test on whether a reference points into 1249 // the collection set or not. Each of the array's elements denotes whether the 1250 // corresponding region is in the collection set or not. 1251 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1252 1253 public: 1254 1255 inline InCSetState in_cset_state(const oop obj); 1256 1257 // Return "TRUE" iff the given object address is in the reserved 1258 // region of g1. 1259 bool is_in_g1_reserved(const void* p) const { 1260 return _hrm.reserved().contains(p); 1261 } 1262 1263 // Returns a MemRegion that corresponds to the space that has been 1264 // reserved for the heap 1265 MemRegion g1_reserved() const { 1266 return _hrm.reserved(); 1267 } 1268 1269 virtual bool is_in_closed_subset(const void* p) const; 1270 1271 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1272 return (G1SATBCardTableLoggingModRefBS*) barrier_set(); 1273 } 1274 1275 // This resets the card table to all zeros. It is used after 1276 // a collection pause which used the card table to claim cards. 1277 void cleanUpCardTable(); 1278 1279 // Iteration functions. 1280 1281 // Iterate over all the ref-containing fields of all objects, calling 1282 // "cl.do_oop" on each. 1283 virtual void oop_iterate(ExtendedOopClosure* cl); 1284 1285 // Iterate over all objects, calling "cl.do_object" on each. 1286 virtual void object_iterate(ObjectClosure* cl); 1287 1288 virtual void safe_object_iterate(ObjectClosure* cl) { 1289 object_iterate(cl); 1290 } 1291 1292 // Iterate over all spaces in use in the heap, in ascending address order. 1293 virtual void space_iterate(SpaceClosure* cl); 1294 1295 // Iterate over heap regions, in address order, terminating the 1296 // iteration early if the "doHeapRegion" method returns "true". 1297 void heap_region_iterate(HeapRegionClosure* blk) const; 1298 1299 // Return the region with the given index. It assumes the index is valid. 1300 inline HeapRegion* region_at(uint index) const; 1301 1302 // Calculate the region index of the given address. Given address must be 1303 // within the heap. 1304 inline uint addr_to_region(HeapWord* addr) const; 1305 1306 inline HeapWord* bottom_addr_for_region(uint index) const; 1307 1308 // Divide the heap region sequence into "chunks" of some size (the number 1309 // of regions divided by the number of parallel threads times some 1310 // overpartition factor, currently 4). Assumes that this will be called 1311 // in parallel by ParallelGCThreads worker threads with discinct worker 1312 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1313 // calls will use the same "claim_value", and that that claim value is 1314 // different from the claim_value of any heap region before the start of 1315 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1316 // attempting to claim the first region in each chunk, and, if 1317 // successful, applying the closure to each region in the chunk (and 1318 // setting the claim value of the second and subsequent regions of the 1319 // chunk.) For now requires that "doHeapRegion" always returns "false", 1320 // i.e., that a closure never attempt to abort a traversal. 1321 void heap_region_par_iterate_chunked(HeapRegionClosure* cl, 1322 uint worker_id, 1323 uint num_workers, 1324 jint claim_value) const; 1325 1326 // It resets all the region claim values to the default. 1327 void reset_heap_region_claim_values(); 1328 1329 // Resets the claim values of regions in the current 1330 // collection set to the default. 1331 void reset_cset_heap_region_claim_values(); 1332 1333 #ifdef ASSERT 1334 bool check_heap_region_claim_values(jint claim_value); 1335 1336 // Same as the routine above but only checks regions in the 1337 // current collection set. 1338 bool check_cset_heap_region_claim_values(jint claim_value); 1339 #endif // ASSERT 1340 1341 // Clear the cached cset start regions and (more importantly) 1342 // the time stamps. Called when we reset the GC time stamp. 1343 void clear_cset_start_regions(); 1344 1345 // Given the id of a worker, obtain or calculate a suitable 1346 // starting region for iterating over the current collection set. 1347 HeapRegion* start_cset_region_for_worker(uint worker_i); 1348 1349 // Iterate over the regions (if any) in the current collection set. 1350 void collection_set_iterate(HeapRegionClosure* blk); 1351 1352 // As above but starting from region r 1353 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1354 1355 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1356 1357 // A CollectedHeap will contain some number of spaces. This finds the 1358 // space containing a given address, or else returns NULL. 1359 virtual Space* space_containing(const void* addr) const; 1360 1361 // Returns the HeapRegion that contains addr. addr must not be NULL. 1362 template <class T> 1363 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1364 1365 // Returns the HeapRegion that contains addr. addr must not be NULL. 1366 // If addr is within a humongous continues region, it returns its humongous start region. 1367 template <class T> 1368 inline HeapRegion* heap_region_containing(const T addr) const; 1369 1370 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1371 // each address in the (reserved) heap is a member of exactly 1372 // one block. The defining characteristic of a block is that it is 1373 // possible to find its size, and thus to progress forward to the next 1374 // block. (Blocks may be of different sizes.) Thus, blocks may 1375 // represent Java objects, or they might be free blocks in a 1376 // free-list-based heap (or subheap), as long as the two kinds are 1377 // distinguishable and the size of each is determinable. 1378 1379 // Returns the address of the start of the "block" that contains the 1380 // address "addr". We say "blocks" instead of "object" since some heaps 1381 // may not pack objects densely; a chunk may either be an object or a 1382 // non-object. 1383 virtual HeapWord* block_start(const void* addr) const; 1384 1385 // Requires "addr" to be the start of a chunk, and returns its size. 1386 // "addr + size" is required to be the start of a new chunk, or the end 1387 // of the active area of the heap. 1388 virtual size_t block_size(const HeapWord* addr) const; 1389 1390 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1391 // the block is an object. 1392 virtual bool block_is_obj(const HeapWord* addr) const; 1393 1394 // Does this heap support heap inspection? (+PrintClassHistogram) 1395 virtual bool supports_heap_inspection() const { return true; } 1396 1397 // Section on thread-local allocation buffers (TLABs) 1398 // See CollectedHeap for semantics. 1399 1400 bool supports_tlab_allocation() const; 1401 size_t tlab_capacity(Thread* ignored) const; 1402 size_t tlab_used(Thread* ignored) const; 1403 size_t max_tlab_size() const; 1404 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1405 1406 // Can a compiler initialize a new object without store barriers? 1407 // This permission only extends from the creation of a new object 1408 // via a TLAB up to the first subsequent safepoint. If such permission 1409 // is granted for this heap type, the compiler promises to call 1410 // defer_store_barrier() below on any slow path allocation of 1411 // a new object for which such initializing store barriers will 1412 // have been elided. G1, like CMS, allows this, but should be 1413 // ready to provide a compensating write barrier as necessary 1414 // if that storage came out of a non-young region. The efficiency 1415 // of this implementation depends crucially on being able to 1416 // answer very efficiently in constant time whether a piece of 1417 // storage in the heap comes from a young region or not. 1418 // See ReduceInitialCardMarks. 1419 virtual bool can_elide_tlab_store_barriers() const { 1420 return true; 1421 } 1422 1423 virtual bool card_mark_must_follow_store() const { 1424 return true; 1425 } 1426 1427 inline bool is_in_young(const oop obj); 1428 1429 #ifdef ASSERT 1430 virtual bool is_in_partial_collection(const void* p); 1431 #endif 1432 1433 virtual bool is_scavengable(const void* addr); 1434 1435 // We don't need barriers for initializing stores to objects 1436 // in the young gen: for the SATB pre-barrier, there is no 1437 // pre-value that needs to be remembered; for the remembered-set 1438 // update logging post-barrier, we don't maintain remembered set 1439 // information for young gen objects. 1440 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1441 1442 // Returns "true" iff the given word_size is "very large". 1443 static bool isHumongous(size_t word_size) { 1444 // Note this has to be strictly greater-than as the TLABs 1445 // are capped at the humongous thresold and we want to 1446 // ensure that we don't try to allocate a TLAB as 1447 // humongous and that we don't allocate a humongous 1448 // object in a TLAB. 1449 return word_size > _humongous_object_threshold_in_words; 1450 } 1451 1452 // Update mod union table with the set of dirty cards. 1453 void updateModUnion(); 1454 1455 // Set the mod union bits corresponding to the given memRegion. Note 1456 // that this is always a safe operation, since it doesn't clear any 1457 // bits. 1458 void markModUnionRange(MemRegion mr); 1459 1460 // Records the fact that a marking phase is no longer in progress. 1461 void set_marking_complete() { 1462 _mark_in_progress = false; 1463 } 1464 void set_marking_started() { 1465 _mark_in_progress = true; 1466 } 1467 bool mark_in_progress() { 1468 return _mark_in_progress; 1469 } 1470 1471 // Print the maximum heap capacity. 1472 virtual size_t max_capacity() const; 1473 1474 virtual jlong millis_since_last_gc(); 1475 1476 1477 // Convenience function to be used in situations where the heap type can be 1478 // asserted to be this type. 1479 static G1CollectedHeap* heap(); 1480 1481 void set_region_short_lived_locked(HeapRegion* hr); 1482 // add appropriate methods for any other surv rate groups 1483 1484 YoungList* young_list() const { return _young_list; } 1485 1486 // debugging 1487 bool check_young_list_well_formed() { 1488 return _young_list->check_list_well_formed(); 1489 } 1490 1491 bool check_young_list_empty(bool check_heap, 1492 bool check_sample = true); 1493 1494 // *** Stuff related to concurrent marking. It's not clear to me that so 1495 // many of these need to be public. 1496 1497 // The functions below are helper functions that a subclass of 1498 // "CollectedHeap" can use in the implementation of its virtual 1499 // functions. 1500 // This performs a concurrent marking of the live objects in a 1501 // bitmap off to the side. 1502 void doConcurrentMark(); 1503 1504 bool isMarkedPrev(oop obj) const; 1505 bool isMarkedNext(oop obj) const; 1506 1507 // Determine if an object is dead, given the object and also 1508 // the region to which the object belongs. An object is dead 1509 // iff a) it was not allocated since the last mark and b) it 1510 // is not marked. 1511 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1512 return 1513 !hr->obj_allocated_since_prev_marking(obj) && 1514 !isMarkedPrev(obj); 1515 } 1516 1517 // This function returns true when an object has been 1518 // around since the previous marking and hasn't yet 1519 // been marked during this marking. 1520 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1521 return 1522 !hr->obj_allocated_since_next_marking(obj) && 1523 !isMarkedNext(obj); 1524 } 1525 1526 // Determine if an object is dead, given only the object itself. 1527 // This will find the region to which the object belongs and 1528 // then call the region version of the same function. 1529 1530 // Added if it is NULL it isn't dead. 1531 1532 inline bool is_obj_dead(const oop obj) const; 1533 1534 inline bool is_obj_ill(const oop obj) const; 1535 1536 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1537 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1538 bool is_marked(oop obj, VerifyOption vo); 1539 const char* top_at_mark_start_str(VerifyOption vo); 1540 1541 ConcurrentMark* concurrent_mark() const { return _cm; } 1542 1543 // Refinement 1544 1545 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1546 1547 // The dirty cards region list is used to record a subset of regions 1548 // whose cards need clearing. The list if populated during the 1549 // remembered set scanning and drained during the card table 1550 // cleanup. Although the methods are reentrant, population/draining 1551 // phases must not overlap. For synchronization purposes the last 1552 // element on the list points to itself. 1553 HeapRegion* _dirty_cards_region_list; 1554 void push_dirty_cards_region(HeapRegion* hr); 1555 HeapRegion* pop_dirty_cards_region(); 1556 1557 // Optimized nmethod scanning support routines 1558 1559 // Register the given nmethod with the G1 heap 1560 virtual void register_nmethod(nmethod* nm); 1561 1562 // Unregister the given nmethod from the G1 heap 1563 virtual void unregister_nmethod(nmethod* nm); 1564 1565 // Free up superfluous code root memory. 1566 void purge_code_root_memory(); 1567 1568 // Rebuild the stong code root lists for each region 1569 // after a full GC 1570 void rebuild_strong_code_roots(); 1571 1572 // Delete entries for dead interned string and clean up unreferenced symbols 1573 // in symbol table, possibly in parallel. 1574 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1575 1576 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1577 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1578 1579 // Redirty logged cards in the refinement queue. 1580 void redirty_logged_cards(); 1581 // Verification 1582 1583 // The following is just to alert the verification code 1584 // that a full collection has occurred and that the 1585 // remembered sets are no longer up to date. 1586 bool _full_collection; 1587 void set_full_collection() { _full_collection = true;} 1588 void clear_full_collection() {_full_collection = false;} 1589 bool full_collection() {return _full_collection;} 1590 1591 // Perform any cleanup actions necessary before allowing a verification. 1592 virtual void prepare_for_verify(); 1593 1594 // Perform verification. 1595 1596 // vo == UsePrevMarking -> use "prev" marking information, 1597 // vo == UseNextMarking -> use "next" marking information 1598 // vo == UseMarkWord -> use the mark word in the object header 1599 // 1600 // NOTE: Only the "prev" marking information is guaranteed to be 1601 // consistent most of the time, so most calls to this should use 1602 // vo == UsePrevMarking. 1603 // Currently, there is only one case where this is called with 1604 // vo == UseNextMarking, which is to verify the "next" marking 1605 // information at the end of remark. 1606 // Currently there is only one place where this is called with 1607 // vo == UseMarkWord, which is to verify the marking during a 1608 // full GC. 1609 void verify(bool silent, VerifyOption vo); 1610 1611 // Override; it uses the "prev" marking information 1612 virtual void verify(bool silent); 1613 1614 // The methods below are here for convenience and dispatch the 1615 // appropriate method depending on value of the given VerifyOption 1616 // parameter. The values for that parameter, and their meanings, 1617 // are the same as those above. 1618 1619 bool is_obj_dead_cond(const oop obj, 1620 const HeapRegion* hr, 1621 const VerifyOption vo) const; 1622 1623 bool is_obj_dead_cond(const oop obj, 1624 const VerifyOption vo) const; 1625 1626 G1HeapSummary create_g1_heap_summary(); 1627 1628 // Printing 1629 1630 virtual void print_on(outputStream* st) const; 1631 virtual void print_extended_on(outputStream* st) const; 1632 virtual void print_on_error(outputStream* st) const; 1633 1634 virtual void print_gc_threads_on(outputStream* st) const; 1635 virtual void gc_threads_do(ThreadClosure* tc) const; 1636 1637 // Override 1638 void print_tracing_info() const; 1639 1640 // The following two methods are helpful for debugging RSet issues. 1641 void print_cset_rsets() PRODUCT_RETURN; 1642 void print_all_rsets() PRODUCT_RETURN; 1643 1644 public: 1645 size_t pending_card_num(); 1646 size_t cards_scanned(); 1647 1648 protected: 1649 size_t _max_heap_capacity; 1650 }; 1651 1652 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP