1 /* 2 * Copyright (c) 2001, 2014, 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 class Ticks; 79 80 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 81 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 82 83 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 84 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 85 86 class YoungList : public CHeapObj<mtGC> { 87 private: 88 G1CollectedHeap* _g1h; 89 90 HeapRegion* _head; 91 92 HeapRegion* _survivor_head; 93 HeapRegion* _survivor_tail; 94 95 HeapRegion* _curr; 96 97 uint _length; 98 uint _survivor_length; 99 100 size_t _last_sampled_rs_lengths; 101 size_t _sampled_rs_lengths; 102 103 void empty_list(HeapRegion* list); 104 105 public: 106 YoungList(G1CollectedHeap* g1h); 107 108 void push_region(HeapRegion* hr); 109 void add_survivor_region(HeapRegion* hr); 110 111 void empty_list(); 112 bool is_empty() { return _length == 0; } 113 uint length() { return _length; } 114 uint survivor_length() { return _survivor_length; } 115 116 // Currently we do not keep track of the used byte sum for the 117 // young list and the survivors and it'd be quite a lot of work to 118 // do so. When we'll eventually replace the young list with 119 // instances of HeapRegionLinkedList we'll get that for free. So, 120 // we'll report the more accurate information then. 121 size_t eden_used_bytes() { 122 assert(length() >= survivor_length(), "invariant"); 123 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 124 } 125 size_t survivor_used_bytes() { 126 return (size_t) survivor_length() * HeapRegion::GrainBytes; 127 } 128 129 void rs_length_sampling_init(); 130 bool rs_length_sampling_more(); 131 void rs_length_sampling_next(); 132 133 void reset_sampled_info() { 134 _last_sampled_rs_lengths = 0; 135 } 136 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 137 138 // for development purposes 139 void reset_auxilary_lists(); 140 void clear() { _head = NULL; _length = 0; } 141 142 void clear_survivors() { 143 _survivor_head = NULL; 144 _survivor_tail = NULL; 145 _survivor_length = 0; 146 } 147 148 HeapRegion* first_region() { return _head; } 149 HeapRegion* first_survivor_region() { return _survivor_head; } 150 HeapRegion* last_survivor_region() { return _survivor_tail; } 151 152 // debugging 153 bool check_list_well_formed(); 154 bool check_list_empty(bool check_sample = true); 155 void print(); 156 }; 157 158 // The G1 STW is alive closure. 159 // An instance is embedded into the G1CH and used as the 160 // (optional) _is_alive_non_header closure in the STW 161 // reference processor. It is also extensively used during 162 // reference processing during STW evacuation pauses. 163 class G1STWIsAliveClosure: public BoolObjectClosure { 164 G1CollectedHeap* _g1; 165 public: 166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 167 bool do_object_b(oop p); 168 }; 169 170 class RefineCardTableEntryClosure; 171 172 class G1RegionMappingChangedListener : public G1MappingChangedListener { 173 private: 174 void reset_from_card_cache(uint start_idx, size_t num_regions); 175 public: 176 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 177 }; 178 179 class G1CollectedHeap : public SharedHeap { 180 friend class VM_CollectForMetadataAllocation; 181 friend class VM_G1CollectForAllocation; 182 friend class VM_G1CollectFull; 183 friend class VM_G1IncCollectionPause; 184 friend class VMStructs; 185 friend class MutatorAllocRegion; 186 friend class SurvivorGCAllocRegion; 187 friend class OldGCAllocRegion; 188 friend class G1Allocator; 189 friend class G1DefaultAllocator; 190 friend class G1ResManAllocator; 191 192 // Closures used in implementation. 193 template <G1Barrier barrier, G1Mark do_mark_object> 194 friend class G1ParCopyClosure; 195 friend class G1IsAliveClosure; 196 friend class G1EvacuateFollowersClosure; 197 friend class G1ParScanThreadState; 198 friend class G1ParScanClosureSuper; 199 friend class G1ParEvacuateFollowersClosure; 200 friend class G1ParTask; 201 friend class G1ParGCAllocator; 202 friend class G1DefaultParGCAllocator; 203 friend class G1FreeGarbageRegionClosure; 204 friend class RefineCardTableEntryClosure; 205 friend class G1PrepareCompactClosure; 206 friend class RegionSorter; 207 friend class RegionResetter; 208 friend class CountRCClosure; 209 friend class EvacPopObjClosure; 210 friend class G1ParCleanupCTTask; 211 212 friend class G1FreeHumongousRegionClosure; 213 // Other related classes. 214 friend class G1MarkSweep; 215 216 private: 217 // The one and only G1CollectedHeap, so static functions can find it. 218 static G1CollectedHeap* _g1h; 219 220 static size_t _humongous_object_threshold_in_words; 221 222 // The secondary free list which contains regions that have been 223 // freed up during the cleanup process. This will be appended to 224 // the master free list when appropriate. 225 FreeRegionList _secondary_free_list; 226 227 // It keeps track of the old regions. 228 HeapRegionSet _old_set; 229 230 // It keeps track of the humongous regions. 231 HeapRegionSet _humongous_set; 232 233 void clear_humongous_is_live_table(); 234 void eagerly_reclaim_humongous_regions(); 235 236 // The number of regions we could create by expansion. 237 uint _expansion_regions; 238 239 // The block offset table for the G1 heap. 240 G1BlockOffsetSharedArray* _bot_shared; 241 242 // Tears down the region sets / lists so that they are empty and the 243 // regions on the heap do not belong to a region set / list. The 244 // only exception is the humongous set which we leave unaltered. If 245 // free_list_only is true, it will only tear down the master free 246 // list. It is called before a Full GC (free_list_only == false) or 247 // before heap shrinking (free_list_only == true). 248 void tear_down_region_sets(bool free_list_only); 249 250 // Rebuilds the region sets / lists so that they are repopulated to 251 // reflect the contents of the heap. The only exception is the 252 // humongous set which was not torn down in the first place. If 253 // free_list_only is true, it will only rebuild the master free 254 // list. It is called after a Full GC (free_list_only == false) or 255 // after heap shrinking (free_list_only == true). 256 void rebuild_region_sets(bool free_list_only); 257 258 // Callback for region mapping changed events. 259 G1RegionMappingChangedListener _listener; 260 261 // The sequence of all heap regions in the heap. 262 HeapRegionManager _hrm; 263 264 // Class that handles the different kinds of allocations. 265 G1Allocator* _allocator; 266 267 // Statistics for each allocation context 268 AllocationContextStats _allocation_context_stats; 269 270 // PLAB sizing policy for survivors. 271 PLABStats _survivor_plab_stats; 272 273 // PLAB sizing policy for tenured objects. 274 PLABStats _old_plab_stats; 275 276 // It specifies whether we should attempt to expand the heap after a 277 // region allocation failure. If heap expansion fails we set this to 278 // false so that we don't re-attempt the heap expansion (it's likely 279 // that subsequent expansion attempts will also fail if one fails). 280 // Currently, it is only consulted during GC and it's reset at the 281 // start of each GC. 282 bool _expand_heap_after_alloc_failure; 283 284 // It resets the mutator alloc region before new allocations can take place. 285 void init_mutator_alloc_region(); 286 287 // It releases the mutator alloc region. 288 void release_mutator_alloc_region(); 289 290 // It initializes the GC alloc regions at the start of a GC. 291 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 292 293 // It releases the GC alloc regions at the end of a GC. 294 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 295 296 // It does any cleanup that needs to be done on the GC alloc regions 297 // before a Full GC. 298 void abandon_gc_alloc_regions(); 299 300 // Helper for monitoring and management support. 301 G1MonitoringSupport* _g1mm; 302 303 // Records whether the region at the given index is kept live by roots or 304 // references from the young generation. 305 class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> { 306 protected: 307 bool default_value() const { return false; } 308 public: 309 void clear() { G1BiasedMappedArray<bool>::clear(); } 310 void set_live(uint region) { 311 set_by_index(region, true); 312 } 313 bool is_live(uint region) { 314 return get_by_index(region); 315 } 316 }; 317 318 HumongousIsLiveBiasedMappedArray _humongous_is_live; 319 // Stores whether during humongous object registration we found candidate regions. 320 // If not, we can skip a few steps. 321 bool _has_humongous_reclaim_candidates; 322 323 volatile unsigned _gc_time_stamp; 324 325 size_t* _surviving_young_words; 326 327 G1HRPrinter _hr_printer; 328 329 void setup_surviving_young_words(); 330 void update_surviving_young_words(size_t* surv_young_words); 331 void cleanup_surviving_young_words(); 332 333 // It decides whether an explicit GC should start a concurrent cycle 334 // instead of doing a STW GC. Currently, a concurrent cycle is 335 // explicitly started if: 336 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 337 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 338 // (c) cause == _g1_humongous_allocation 339 bool should_do_concurrent_full_gc(GCCause::Cause cause); 340 341 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 342 // concurrent cycles) we have started. 343 volatile unsigned int _old_marking_cycles_started; 344 345 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 346 // concurrent cycles) we have completed. 347 volatile unsigned int _old_marking_cycles_completed; 348 349 bool _concurrent_cycle_started; 350 351 // This is a non-product method that is helpful for testing. It is 352 // called at the end of a GC and artificially expands the heap by 353 // allocating a number of dead regions. This way we can induce very 354 // frequent marking cycles and stress the cleanup / concurrent 355 // cleanup code more (as all the regions that will be allocated by 356 // this method will be found dead by the marking cycle). 357 void allocate_dummy_regions() PRODUCT_RETURN; 358 359 // Clear RSets after a compaction. It also resets the GC time stamps. 360 void clear_rsets_post_compaction(); 361 362 // If the HR printer is active, dump the state of the regions in the 363 // heap after a compaction. 364 void print_hrm_post_compaction(); 365 366 double verify(bool guard, const char* msg); 367 void verify_before_gc(); 368 void verify_after_gc(); 369 370 void log_gc_header(); 371 void log_gc_footer(double pause_time_sec); 372 373 // These are macros so that, if the assert fires, we get the correct 374 // line number, file, etc. 375 376 #define heap_locking_asserts_err_msg(_extra_message_) \ 377 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 378 (_extra_message_), \ 379 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 380 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 381 BOOL_TO_STR(Thread::current()->is_VM_thread())) 382 383 #define assert_heap_locked() \ 384 do { \ 385 assert(Heap_lock->owned_by_self(), \ 386 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 387 } while (0) 388 389 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 390 do { \ 391 assert(Heap_lock->owned_by_self() || \ 392 (SafepointSynchronize::is_at_safepoint() && \ 393 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 394 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 395 "should be at a safepoint")); \ 396 } while (0) 397 398 #define assert_heap_locked_and_not_at_safepoint() \ 399 do { \ 400 assert(Heap_lock->owned_by_self() && \ 401 !SafepointSynchronize::is_at_safepoint(), \ 402 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 403 "should not be at a safepoint")); \ 404 } while (0) 405 406 #define assert_heap_not_locked() \ 407 do { \ 408 assert(!Heap_lock->owned_by_self(), \ 409 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 410 } while (0) 411 412 #define assert_heap_not_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 not be holding the Heap_lock and " \ 417 "should not be at a safepoint")); \ 418 } while (0) 419 420 #define assert_at_safepoint(_should_be_vm_thread_) \ 421 do { \ 422 assert(SafepointSynchronize::is_at_safepoint() && \ 423 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 424 heap_locking_asserts_err_msg("should be at a safepoint")); \ 425 } while (0) 426 427 #define assert_not_at_safepoint() \ 428 do { \ 429 assert(!SafepointSynchronize::is_at_safepoint(), \ 430 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 431 } while (0) 432 433 protected: 434 435 // The young region list. 436 YoungList* _young_list; 437 438 // The current policy object for the collector. 439 G1CollectorPolicy* _g1_policy; 440 441 // This is the second level of trying to allocate a new region. If 442 // new_region() didn't find a region on the free_list, this call will 443 // check whether there's anything available on the 444 // secondary_free_list and/or wait for more regions to appear on 445 // that list, if _free_regions_coming is set. 446 HeapRegion* new_region_try_secondary_free_list(bool is_old); 447 448 // Try to allocate a single non-humongous HeapRegion sufficient for 449 // an allocation of the given word_size. If do_expand is true, 450 // attempt to expand the heap if necessary to satisfy the allocation 451 // request. If the region is to be used as an old region or for a 452 // humongous object, set is_old to true. If not, to false. 453 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 454 455 // Initialize a contiguous set of free regions of length num_regions 456 // and starting at index first so that they appear as a single 457 // humongous region. 458 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 459 uint num_regions, 460 size_t word_size, 461 AllocationContext_t context); 462 463 // Attempt to allocate a humongous object of the given size. Return 464 // NULL if unsuccessful. 465 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 466 467 // The following two methods, allocate_new_tlab() and 468 // mem_allocate(), are the two main entry points from the runtime 469 // into the G1's allocation routines. They have the following 470 // assumptions: 471 // 472 // * They should both be called outside safepoints. 473 // 474 // * They should both be called without holding the Heap_lock. 475 // 476 // * All allocation requests for new TLABs should go to 477 // allocate_new_tlab(). 478 // 479 // * All non-TLAB allocation requests should go to mem_allocate(). 480 // 481 // * If either call cannot satisfy the allocation request using the 482 // current allocating region, they will try to get a new one. If 483 // this fails, they will attempt to do an evacuation pause and 484 // retry the allocation. 485 // 486 // * If all allocation attempts fail, even after trying to schedule 487 // an evacuation pause, allocate_new_tlab() will return NULL, 488 // whereas mem_allocate() will attempt a heap expansion and/or 489 // schedule a Full GC. 490 // 491 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 492 // should never be called with word_size being humongous. All 493 // humongous allocation requests should go to mem_allocate() which 494 // will satisfy them with a special path. 495 496 virtual HeapWord* allocate_new_tlab(size_t word_size); 497 498 virtual HeapWord* mem_allocate(size_t word_size, 499 bool* gc_overhead_limit_was_exceeded); 500 501 // The following three methods take a gc_count_before_ret 502 // parameter which is used to return the GC count if the method 503 // returns NULL. Given that we are required to read the GC count 504 // while holding the Heap_lock, and these paths will take the 505 // Heap_lock at some point, it's easier to get them to read the GC 506 // count while holding the Heap_lock before they return NULL instead 507 // of the caller (namely: mem_allocate()) having to also take the 508 // Heap_lock just to read the GC count. 509 510 // First-level mutator allocation attempt: try to allocate out of 511 // the mutator alloc region without taking the Heap_lock. This 512 // should only be used for non-humongous allocations. 513 inline HeapWord* attempt_allocation(size_t word_size, 514 unsigned int* gc_count_before_ret, 515 int* gclocker_retry_count_ret); 516 517 // Second-level mutator allocation attempt: take the Heap_lock and 518 // retry the allocation attempt, potentially scheduling a GC 519 // pause. This should only be used for non-humongous allocations. 520 HeapWord* attempt_allocation_slow(size_t word_size, 521 AllocationContext_t context, 522 unsigned int* gc_count_before_ret, 523 int* gclocker_retry_count_ret); 524 525 // Takes the Heap_lock and attempts a humongous allocation. It can 526 // potentially schedule a GC pause. 527 HeapWord* attempt_allocation_humongous(size_t word_size, 528 unsigned int* gc_count_before_ret, 529 int* gclocker_retry_count_ret); 530 531 // Allocation attempt that should be called during safepoints (e.g., 532 // at the end of a successful GC). expect_null_mutator_alloc_region 533 // specifies whether the mutator alloc region is expected to be NULL 534 // or not. 535 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 536 AllocationContext_t context, 537 bool expect_null_mutator_alloc_region); 538 539 // It dirties the cards that cover the block so that so that the post 540 // write barrier never queues anything when updating objects on this 541 // block. It is assumed (and in fact we assert) that the block 542 // belongs to a young region. 543 inline void dirty_young_block(HeapWord* start, size_t word_size); 544 545 // Allocate blocks during garbage collection. Will ensure an 546 // allocation region, either by picking one or expanding the 547 // heap, and then allocate a block of the given size. The block 548 // may not be a humongous - it must fit into a single heap region. 549 inline HeapWord* par_allocate_during_gc(InCSetState dest, 550 size_t word_size, 551 AllocationContext_t context); 552 // Ensure that no further allocations can happen in "r", bearing in mind 553 // that parallel threads might be attempting allocations. 554 void par_allocate_remaining_space(HeapRegion* r); 555 556 // Allocation attempt during GC for a survivor object / PLAB. 557 inline HeapWord* survivor_attempt_allocation(size_t word_size, 558 AllocationContext_t context); 559 560 // Allocation attempt during GC for an old object / PLAB. 561 inline HeapWord* old_attempt_allocation(size_t word_size, 562 AllocationContext_t context); 563 564 // These methods are the "callbacks" from the G1AllocRegion class. 565 566 // For mutator alloc regions. 567 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 568 void retire_mutator_alloc_region(HeapRegion* alloc_region, 569 size_t allocated_bytes); 570 571 // For GC alloc regions. 572 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 573 InCSetState dest); 574 void retire_gc_alloc_region(HeapRegion* alloc_region, 575 size_t allocated_bytes, InCSetState dest); 576 577 // - if explicit_gc is true, the GC is for a System.gc() or a heap 578 // inspection request and should collect the entire heap 579 // - if clear_all_soft_refs is true, all soft references should be 580 // cleared during the GC 581 // - if explicit_gc is false, word_size describes the allocation that 582 // the GC should attempt (at least) to satisfy 583 // - it returns false if it is unable to do the collection due to the 584 // GC locker being active, true otherwise 585 bool do_collection(bool explicit_gc, 586 bool clear_all_soft_refs, 587 size_t word_size); 588 589 // Callback from VM_G1CollectFull operation. 590 // Perform a full collection. 591 virtual void do_full_collection(bool clear_all_soft_refs); 592 593 // Resize the heap if necessary after a full collection. If this is 594 // after a collect-for allocation, "word_size" is the allocation size, 595 // and will be considered part of the used portion of the heap. 596 void resize_if_necessary_after_full_collection(size_t word_size); 597 598 // Callback from VM_G1CollectForAllocation operation. 599 // This function does everything necessary/possible to satisfy a 600 // failed allocation request (including collection, expansion, etc.) 601 HeapWord* satisfy_failed_allocation(size_t word_size, 602 AllocationContext_t context, 603 bool* succeeded); 604 605 // Attempting to expand the heap sufficiently 606 // to support an allocation of the given "word_size". If 607 // successful, perform the allocation and return the address of the 608 // allocated block, or else "NULL". 609 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 610 611 // Process any reference objects discovered during 612 // an incremental evacuation pause. 613 void process_discovered_references(uint no_of_gc_workers); 614 615 // Enqueue any remaining discovered references 616 // after processing. 617 void enqueue_discovered_references(uint no_of_gc_workers); 618 619 public: 620 621 G1Allocator* allocator() { 622 return _allocator; 623 } 624 625 G1MonitoringSupport* g1mm() { 626 assert(_g1mm != NULL, "should have been initialized"); 627 return _g1mm; 628 } 629 630 // Expand the garbage-first heap by at least the given size (in bytes!). 631 // Returns true if the heap was expanded by the requested amount; 632 // false otherwise. 633 // (Rounds up to a HeapRegion boundary.) 634 bool expand(size_t expand_bytes); 635 636 // Returns the PLAB statistics for a given destination. 637 inline PLABStats* alloc_buffer_stats(InCSetState dest); 638 639 // Determines PLAB size for a given destination. 640 inline size_t desired_plab_sz(InCSetState dest); 641 642 inline AllocationContextStats& allocation_context_stats(); 643 644 // Do anything common to GC's. 645 virtual void gc_prologue(bool full); 646 virtual void gc_epilogue(bool full); 647 648 inline void set_humongous_is_live(oop obj); 649 650 bool humongous_is_live(uint region) { 651 return _humongous_is_live.is_live(region); 652 } 653 654 // Returns whether the given region (which must be a humongous (start) region) 655 // is to be considered conservatively live regardless of any other conditions. 656 bool humongous_region_is_always_live(uint index); 657 // Register the given region to be part of the collection set. 658 inline void register_humongous_region_with_in_cset_fast_test(uint index); 659 // Register regions with humongous objects (actually on the start region) in 660 // the in_cset_fast_test table. 661 void register_humongous_regions_with_in_cset_fast_test(); 662 // We register a region with the fast "in collection set" test. We 663 // simply set to true the array slot corresponding to this region. 664 void register_young_region_with_in_cset_fast_test(HeapRegion* r) { 665 _in_cset_fast_test.set_in_young(r->hrm_index()); 666 } 667 void register_old_region_with_in_cset_fast_test(HeapRegion* r) { 668 _in_cset_fast_test.set_in_old(r->hrm_index()); 669 } 670 671 // This is a fast test on whether a reference points into the 672 // collection set or not. Assume that the reference 673 // points into the heap. 674 inline bool in_cset_fast_test(oop obj); 675 676 void clear_cset_fast_test() { 677 _in_cset_fast_test.clear(); 678 } 679 680 // This is called at the start of either a concurrent cycle or a Full 681 // GC to update the number of old marking cycles started. 682 void increment_old_marking_cycles_started(); 683 684 // This is called at the end of either a concurrent cycle or a Full 685 // GC to update the number of old marking cycles completed. Those two 686 // can happen in a nested fashion, i.e., we start a concurrent 687 // cycle, a Full GC happens half-way through it which ends first, 688 // and then the cycle notices that a Full GC happened and ends 689 // too. The concurrent parameter is a boolean to help us do a bit 690 // tighter consistency checking in the method. If concurrent is 691 // false, the caller is the inner caller in the nesting (i.e., the 692 // Full GC). If concurrent is true, the caller is the outer caller 693 // in this nesting (i.e., the concurrent cycle). Further nesting is 694 // not currently supported. The end of this call also notifies 695 // the FullGCCount_lock in case a Java thread is waiting for a full 696 // GC to happen (e.g., it called System.gc() with 697 // +ExplicitGCInvokesConcurrent). 698 void increment_old_marking_cycles_completed(bool concurrent); 699 700 unsigned int old_marking_cycles_completed() { 701 return _old_marking_cycles_completed; 702 } 703 704 void register_concurrent_cycle_start(const Ticks& start_time); 705 void register_concurrent_cycle_end(); 706 void trace_heap_after_concurrent_cycle(); 707 708 G1YCType yc_type(); 709 710 G1HRPrinter* hr_printer() { return &_hr_printer; } 711 712 // Frees a non-humongous region by initializing its contents and 713 // adding it to the free list that's passed as a parameter (this is 714 // usually a local list which will be appended to the master free 715 // list later). The used bytes of freed regions are accumulated in 716 // pre_used. If par is true, the region's RSet will not be freed 717 // up. The assumption is that this will be done later. 718 // The locked parameter indicates if the caller has already taken 719 // care of proper synchronization. This may allow some optimizations. 720 void free_region(HeapRegion* hr, 721 FreeRegionList* free_list, 722 bool par, 723 bool locked = false); 724 725 // Frees a humongous region by collapsing it into individual regions 726 // and calling free_region() for each of them. The freed regions 727 // will be added to the free list that's passed as a parameter (this 728 // is 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 void free_humongous_region(HeapRegion* hr, 733 FreeRegionList* free_list, 734 bool par); 735 protected: 736 737 // Shrink the garbage-first heap by at most the given size (in bytes!). 738 // (Rounds down to a HeapRegion boundary.) 739 virtual void shrink(size_t expand_bytes); 740 void shrink_helper(size_t expand_bytes); 741 742 #if TASKQUEUE_STATS 743 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 744 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 745 void reset_taskqueue_stats(); 746 #endif // TASKQUEUE_STATS 747 748 // Schedule the VM operation that will do an evacuation pause to 749 // satisfy an allocation request of word_size. *succeeded will 750 // return whether the VM operation was successful (it did do an 751 // evacuation pause) or not (another thread beat us to it or the GC 752 // locker was active). Given that we should not be holding the 753 // Heap_lock when we enter this method, we will pass the 754 // gc_count_before (i.e., total_collections()) as a parameter since 755 // it has to be read while holding the Heap_lock. Currently, both 756 // methods that call do_collection_pause() release the Heap_lock 757 // before the call, so it's easy to read gc_count_before just before. 758 HeapWord* do_collection_pause(size_t word_size, 759 unsigned int gc_count_before, 760 bool* succeeded, 761 GCCause::Cause gc_cause); 762 763 // The guts of the incremental collection pause, executed by the vm 764 // thread. It returns false if it is unable to do the collection due 765 // to the GC locker being active, true otherwise 766 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 767 768 // Actually do the work of evacuating the collection set. 769 void evacuate_collection_set(EvacuationInfo& evacuation_info); 770 771 // The g1 remembered set of the heap. 772 G1RemSet* _g1_rem_set; 773 774 // A set of cards that cover the objects for which the Rsets should be updated 775 // concurrently after the collection. 776 DirtyCardQueueSet _dirty_card_queue_set; 777 778 // The closure used to refine a single card. 779 RefineCardTableEntryClosure* _refine_cte_cl; 780 781 // A function to check the consistency of dirty card logs. 782 void check_ct_logs_at_safepoint(); 783 784 // A DirtyCardQueueSet that is used to hold cards that contain 785 // references into the current collection set. This is used to 786 // update the remembered sets of the regions in the collection 787 // set in the event of an evacuation failure. 788 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 789 790 // After a collection pause, make the regions in the CS into free 791 // regions. 792 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 793 794 // Abandon the current collection set without recording policy 795 // statistics or updating free lists. 796 void abandon_collection_set(HeapRegion* cs_head); 797 798 // Applies "scan_non_heap_roots" to roots outside the heap, 799 // "scan_rs" to roots inside the heap (having done "set_region" to 800 // indicate the region in which the root resides), 801 // and does "scan_metadata" If "scan_rs" is 802 // NULL, then this step is skipped. The "worker_i" 803 // param is for use with parallel roots processing, and should be 804 // the "i" of the calling parallel worker thread's work(i) function. 805 // In the sequential case this param will be ignored. 806 void g1_process_roots(OopClosure* scan_non_heap_roots, 807 OopClosure* scan_non_heap_weak_roots, 808 G1ParPushHeapRSClosure* scan_rs, 809 CLDClosure* scan_strong_clds, 810 CLDClosure* scan_weak_clds, 811 CodeBlobClosure* scan_strong_code, 812 uint worker_i); 813 814 // The concurrent marker (and the thread it runs in.) 815 ConcurrentMark* _cm; 816 ConcurrentMarkThread* _cmThread; 817 bool _mark_in_progress; 818 819 // The concurrent refiner. 820 ConcurrentG1Refine* _cg1r; 821 822 // The parallel task queues 823 RefToScanQueueSet *_task_queues; 824 825 // True iff a evacuation has failed in the current collection. 826 bool _evacuation_failed; 827 828 EvacuationFailedInfo* _evacuation_failed_info_array; 829 830 // Failed evacuations cause some logical from-space objects to have 831 // forwarding pointers to themselves. Reset them. 832 void remove_self_forwarding_pointers(); 833 834 // Together, these store an object with a preserved mark, and its mark value. 835 Stack<oop, mtGC> _objs_with_preserved_marks; 836 Stack<markOop, mtGC> _preserved_marks_of_objs; 837 838 // Preserve the mark of "obj", if necessary, in preparation for its mark 839 // word being overwritten with a self-forwarding-pointer. 840 void preserve_mark_if_necessary(oop obj, markOop m); 841 842 // The stack of evac-failure objects left to be scanned. 843 GrowableArray<oop>* _evac_failure_scan_stack; 844 // The closure to apply to evac-failure objects. 845 846 OopsInHeapRegionClosure* _evac_failure_closure; 847 // Set the field above. 848 void 849 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 850 _evac_failure_closure = evac_failure_closure; 851 } 852 853 // Push "obj" on the scan stack. 854 void push_on_evac_failure_scan_stack(oop obj); 855 // Process scan stack entries until the stack is empty. 856 void drain_evac_failure_scan_stack(); 857 // True iff an invocation of "drain_scan_stack" is in progress; to 858 // prevent unnecessary recursion. 859 bool _drain_in_progress; 860 861 // Do any necessary initialization for evacuation-failure handling. 862 // "cl" is the closure that will be used to process evac-failure 863 // objects. 864 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 865 // Do any necessary cleanup for evacuation-failure handling data 866 // structures. 867 void finalize_for_evac_failure(); 868 869 // An attempt to evacuate "obj" has failed; take necessary steps. 870 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 871 void handle_evacuation_failure_common(oop obj, markOop m); 872 873 #ifndef PRODUCT 874 // Support for forcing evacuation failures. Analogous to 875 // PromotionFailureALot for the other collectors. 876 877 // Records whether G1EvacuationFailureALot should be in effect 878 // for the current GC 879 bool _evacuation_failure_alot_for_current_gc; 880 881 // Used to record the GC number for interval checking when 882 // determining whether G1EvaucationFailureALot is in effect 883 // for the current GC. 884 size_t _evacuation_failure_alot_gc_number; 885 886 // Count of the number of evacuations between failures. 887 volatile size_t _evacuation_failure_alot_count; 888 889 // Set whether G1EvacuationFailureALot should be in effect 890 // for the current GC (based upon the type of GC and which 891 // command line flags are set); 892 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 893 bool during_initial_mark, 894 bool during_marking); 895 896 inline void set_evacuation_failure_alot_for_current_gc(); 897 898 // Return true if it's time to cause an evacuation failure. 899 inline bool evacuation_should_fail(); 900 901 // Reset the G1EvacuationFailureALot counters. Should be called at 902 // the end of an evacuation pause in which an evacuation failure occurred. 903 inline void reset_evacuation_should_fail(); 904 #endif // !PRODUCT 905 906 // ("Weak") Reference processing support. 907 // 908 // G1 has 2 instances of the reference processor class. One 909 // (_ref_processor_cm) handles reference object discovery 910 // and subsequent processing during concurrent marking cycles. 911 // 912 // The other (_ref_processor_stw) handles reference object 913 // discovery and processing during full GCs and incremental 914 // evacuation pauses. 915 // 916 // During an incremental pause, reference discovery will be 917 // temporarily disabled for _ref_processor_cm and will be 918 // enabled for _ref_processor_stw. At the end of the evacuation 919 // pause references discovered by _ref_processor_stw will be 920 // processed and discovery will be disabled. The previous 921 // setting for reference object discovery for _ref_processor_cm 922 // will be re-instated. 923 // 924 // At the start of marking: 925 // * Discovery by the CM ref processor is verified to be inactive 926 // and it's discovered lists are empty. 927 // * Discovery by the CM ref processor is then enabled. 928 // 929 // At the end of marking: 930 // * Any references on the CM ref processor's discovered 931 // lists are processed (possibly MT). 932 // 933 // At the start of full GC we: 934 // * Disable discovery by the CM ref processor and 935 // empty CM ref processor's discovered lists 936 // (without processing any entries). 937 // * Verify that the STW ref processor is inactive and it's 938 // discovered lists are empty. 939 // * Temporarily set STW ref processor discovery as single threaded. 940 // * Temporarily clear the STW ref processor's _is_alive_non_header 941 // field. 942 // * Finally enable discovery by the STW ref processor. 943 // 944 // The STW ref processor is used to record any discovered 945 // references during the full GC. 946 // 947 // At the end of a full GC we: 948 // * Enqueue any reference objects discovered by the STW ref processor 949 // that have non-live referents. This has the side-effect of 950 // making the STW ref processor inactive by disabling discovery. 951 // * Verify that the CM ref processor is still inactive 952 // and no references have been placed on it's discovered 953 // lists (also checked as a precondition during initial marking). 954 955 // The (stw) reference processor... 956 ReferenceProcessor* _ref_processor_stw; 957 958 STWGCTimer* _gc_timer_stw; 959 ConcurrentGCTimer* _gc_timer_cm; 960 961 G1OldTracer* _gc_tracer_cm; 962 G1NewTracer* _gc_tracer_stw; 963 964 // During reference object discovery, the _is_alive_non_header 965 // closure (if non-null) is applied to the referent object to 966 // determine whether the referent is live. If so then the 967 // reference object does not need to be 'discovered' and can 968 // be treated as a regular oop. This has the benefit of reducing 969 // the number of 'discovered' reference objects that need to 970 // be processed. 971 // 972 // Instance of the is_alive closure for embedding into the 973 // STW reference processor as the _is_alive_non_header field. 974 // Supplying a value for the _is_alive_non_header field is 975 // optional but doing so prevents unnecessary additions to 976 // the discovered lists during reference discovery. 977 G1STWIsAliveClosure _is_alive_closure_stw; 978 979 // The (concurrent marking) reference processor... 980 ReferenceProcessor* _ref_processor_cm; 981 982 // Instance of the concurrent mark is_alive closure for embedding 983 // into the Concurrent Marking reference processor as the 984 // _is_alive_non_header field. Supplying a value for the 985 // _is_alive_non_header field is optional but doing so prevents 986 // unnecessary additions to the discovered lists during reference 987 // discovery. 988 G1CMIsAliveClosure _is_alive_closure_cm; 989 990 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 991 HeapRegion** _worker_cset_start_region; 992 993 // Time stamp to validate the regions recorded in the cache 994 // used by G1CollectedHeap::start_cset_region_for_worker(). 995 // The heap region entry for a given worker is valid iff 996 // the associated time stamp value matches the current value 997 // of G1CollectedHeap::_gc_time_stamp. 998 unsigned int* _worker_cset_start_region_time_stamp; 999 1000 enum G1H_process_roots_tasks { 1001 G1H_PS_filter_satb_buffers, 1002 G1H_PS_refProcessor_oops_do, 1003 // Leave this one last. 1004 G1H_PS_NumElements 1005 }; 1006 1007 SubTasksDone* _process_strong_tasks; 1008 1009 volatile bool _free_regions_coming; 1010 1011 public: 1012 1013 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1014 1015 void set_refine_cte_cl_concurrency(bool concurrent); 1016 1017 RefToScanQueue *task_queue(int i) const; 1018 1019 // A set of cards where updates happened during the GC 1020 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1021 1022 // A DirtyCardQueueSet that is used to hold cards that contain 1023 // references into the current collection set. This is used to 1024 // update the remembered sets of the regions in the collection 1025 // set in the event of an evacuation failure. 1026 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1027 { return _into_cset_dirty_card_queue_set; } 1028 1029 // Create a G1CollectedHeap with the specified policy. 1030 // Must call the initialize method afterwards. 1031 // May not return if something goes wrong. 1032 G1CollectedHeap(G1CollectorPolicy* policy); 1033 1034 // Initialize the G1CollectedHeap to have the initial and 1035 // maximum sizes and remembered and barrier sets 1036 // specified by the policy object. 1037 jint initialize(); 1038 1039 virtual void stop(); 1040 1041 // Return the (conservative) maximum heap alignment for any G1 heap 1042 static size_t conservative_max_heap_alignment(); 1043 1044 // Initialize weak reference processing. 1045 virtual void ref_processing_init(); 1046 1047 void set_par_threads(uint t) { 1048 SharedHeap::set_par_threads(t); 1049 // Done in SharedHeap but oddly there are 1050 // two _process_strong_tasks's in a G1CollectedHeap 1051 // so do it here too. 1052 _process_strong_tasks->set_n_threads(t); 1053 } 1054 1055 // Set _n_par_threads according to a policy TBD. 1056 void set_par_threads(); 1057 1058 void set_n_termination(int t) { 1059 _process_strong_tasks->set_n_threads(t); 1060 } 1061 1062 virtual CollectedHeap::Name kind() const { 1063 return CollectedHeap::G1CollectedHeap; 1064 } 1065 1066 // The current policy object for the collector. 1067 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1068 1069 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1070 1071 // Adaptive size policy. No such thing for g1. 1072 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1073 1074 // The rem set and barrier set. 1075 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1076 1077 unsigned get_gc_time_stamp() { 1078 return _gc_time_stamp; 1079 } 1080 1081 inline void reset_gc_time_stamp(); 1082 1083 void check_gc_time_stamps() PRODUCT_RETURN; 1084 1085 inline void increment_gc_time_stamp(); 1086 1087 // Reset the given region's GC timestamp. If it's starts humongous, 1088 // also reset the GC timestamp of its corresponding 1089 // continues humongous regions too. 1090 void reset_gc_time_stamps(HeapRegion* hr); 1091 1092 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1093 DirtyCardQueue* into_cset_dcq, 1094 bool concurrent, uint worker_i); 1095 1096 // The shared block offset table array. 1097 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1098 1099 // Reference Processing accessors 1100 1101 // The STW reference processor.... 1102 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1103 1104 // The Concurrent Marking reference processor... 1105 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1106 1107 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1108 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1109 1110 virtual size_t capacity() const; 1111 virtual size_t used() const; 1112 // This should be called when we're not holding the heap lock. The 1113 // result might be a bit inaccurate. 1114 size_t used_unlocked() const; 1115 size_t recalculate_used() const; 1116 1117 // These virtual functions do the actual allocation. 1118 // Some heaps may offer a contiguous region for shared non-blocking 1119 // allocation, via inlined code (by exporting the address of the top and 1120 // end fields defining the extent of the contiguous allocation region.) 1121 // But G1CollectedHeap doesn't yet support this. 1122 1123 virtual bool is_maximal_no_gc() const { 1124 return _hrm.available() == 0; 1125 } 1126 1127 // The current number of regions in the heap. 1128 uint num_regions() const { return _hrm.length(); } 1129 1130 // The max number of regions in the heap. 1131 uint max_regions() const { return _hrm.max_length(); } 1132 1133 // The number of regions that are completely free. 1134 uint num_free_regions() const { return _hrm.num_free_regions(); } 1135 1136 // The number of regions that are not completely free. 1137 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1138 1139 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1140 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1141 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1142 void verify_dirty_young_regions() PRODUCT_RETURN; 1143 1144 #ifndef PRODUCT 1145 // Make sure that the given bitmap has no marked objects in the 1146 // range [from,limit). If it does, print an error message and return 1147 // false. Otherwise, just return true. bitmap_name should be "prev" 1148 // or "next". 1149 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1150 HeapWord* from, HeapWord* limit); 1151 1152 // Verify that the prev / next bitmap range [tams,end) for the given 1153 // region has no marks. Return true if all is well, false if errors 1154 // are detected. 1155 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1156 #endif // PRODUCT 1157 1158 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1159 // the given region do not have any spurious marks. If errors are 1160 // detected, print appropriate error messages and crash. 1161 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1162 1163 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1164 // have any spurious marks. If errors are detected, print 1165 // appropriate error messages and crash. 1166 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1167 1168 // Do sanity check on the contents of the in-cset fast test table. 1169 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1170 1171 // verify_region_sets() performs verification over the region 1172 // lists. It will be compiled in the product code to be used when 1173 // necessary (i.e., during heap verification). 1174 void verify_region_sets(); 1175 1176 // verify_region_sets_optional() is planted in the code for 1177 // list verification in non-product builds (and it can be enabled in 1178 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1179 #if HEAP_REGION_SET_FORCE_VERIFY 1180 void verify_region_sets_optional() { 1181 verify_region_sets(); 1182 } 1183 #else // HEAP_REGION_SET_FORCE_VERIFY 1184 void verify_region_sets_optional() { } 1185 #endif // HEAP_REGION_SET_FORCE_VERIFY 1186 1187 #ifdef ASSERT 1188 bool is_on_master_free_list(HeapRegion* hr) { 1189 return _hrm.is_free(hr); 1190 } 1191 #endif // ASSERT 1192 1193 // Wrapper for the region list operations that can be called from 1194 // methods outside this class. 1195 1196 void secondary_free_list_add(FreeRegionList* list) { 1197 _secondary_free_list.add_ordered(list); 1198 } 1199 1200 void append_secondary_free_list() { 1201 _hrm.insert_list_into_free_list(&_secondary_free_list); 1202 } 1203 1204 void append_secondary_free_list_if_not_empty_with_lock() { 1205 // If the secondary free list looks empty there's no reason to 1206 // take the lock and then try to append it. 1207 if (!_secondary_free_list.is_empty()) { 1208 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1209 append_secondary_free_list(); 1210 } 1211 } 1212 1213 inline void old_set_remove(HeapRegion* hr); 1214 1215 size_t non_young_capacity_bytes() { 1216 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1217 } 1218 1219 void set_free_regions_coming(); 1220 void reset_free_regions_coming(); 1221 bool free_regions_coming() { return _free_regions_coming; } 1222 void wait_while_free_regions_coming(); 1223 1224 // Determine whether the given region is one that we are using as an 1225 // old GC alloc region. 1226 bool is_old_gc_alloc_region(HeapRegion* hr) { 1227 return _allocator->is_retained_old_region(hr); 1228 } 1229 1230 // Perform a collection of the heap; intended for use in implementing 1231 // "System.gc". This probably implies as full a collection as the 1232 // "CollectedHeap" supports. 1233 virtual void collect(GCCause::Cause cause); 1234 1235 // The same as above but assume that the caller holds the Heap_lock. 1236 void collect_locked(GCCause::Cause cause); 1237 1238 virtual bool copy_allocation_context_stats(const jint* contexts, 1239 jlong* totals, 1240 jbyte* accuracy, 1241 jint len); 1242 1243 // True iff an evacuation has failed in the most-recent collection. 1244 bool evacuation_failed() { return _evacuation_failed; } 1245 1246 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1247 void prepend_to_freelist(FreeRegionList* list); 1248 void decrement_summary_bytes(size_t bytes); 1249 1250 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1251 virtual bool is_in(const void* p) const; 1252 #ifdef ASSERT 1253 // Returns whether p is in one of the available areas of the heap. Slow but 1254 // extensive version. 1255 bool is_in_exact(const void* p) const; 1256 #endif 1257 1258 // Return "TRUE" iff the given object address is within the collection 1259 // set. Slow implementation. 1260 inline bool obj_in_cs(oop obj); 1261 1262 inline bool is_in_cset(oop obj); 1263 1264 inline bool is_in_cset_or_humongous(const oop obj); 1265 1266 private: 1267 // This array is used for a quick test on whether a reference points into 1268 // the collection set or not. Each of the array's elements denotes whether the 1269 // corresponding region is in the collection set or not. 1270 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1271 1272 public: 1273 1274 inline InCSetState in_cset_state(const oop obj); 1275 1276 // Return "TRUE" iff the given object address is in the reserved 1277 // region of g1. 1278 bool is_in_g1_reserved(const void* p) const { 1279 return _hrm.reserved().contains(p); 1280 } 1281 1282 // Returns a MemRegion that corresponds to the space that has been 1283 // reserved for the heap 1284 MemRegion g1_reserved() const { 1285 return _hrm.reserved(); 1286 } 1287 1288 virtual bool is_in_closed_subset(const void* p) const; 1289 1290 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1291 return (G1SATBCardTableLoggingModRefBS*) barrier_set(); 1292 } 1293 1294 // This resets the card table to all zeros. It is used after 1295 // a collection pause which used the card table to claim cards. 1296 void cleanUpCardTable(); 1297 1298 // Iteration functions. 1299 1300 // Iterate over all the ref-containing fields of all objects, calling 1301 // "cl.do_oop" on each. 1302 virtual void oop_iterate(ExtendedOopClosure* cl); 1303 1304 // Iterate over all objects, calling "cl.do_object" on each. 1305 virtual void object_iterate(ObjectClosure* cl); 1306 1307 virtual void safe_object_iterate(ObjectClosure* cl) { 1308 object_iterate(cl); 1309 } 1310 1311 // Iterate over all spaces in use in the heap, in ascending address order. 1312 virtual void space_iterate(SpaceClosure* cl); 1313 1314 // Iterate over heap regions, in address order, terminating the 1315 // iteration early if the "doHeapRegion" method returns "true". 1316 void heap_region_iterate(HeapRegionClosure* blk) const; 1317 1318 // Return the region with the given index. It assumes the index is valid. 1319 inline HeapRegion* region_at(uint index) const; 1320 1321 // Calculate the region index of the given address. Given address must be 1322 // within the heap. 1323 inline uint addr_to_region(HeapWord* addr) const; 1324 1325 inline HeapWord* bottom_addr_for_region(uint index) const; 1326 1327 // Divide the heap region sequence into "chunks" of some size (the number 1328 // of regions divided by the number of parallel threads times some 1329 // overpartition factor, currently 4). Assumes that this will be called 1330 // in parallel by ParallelGCThreads worker threads with discinct worker 1331 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1332 // calls will use the same "claim_value", and that that claim value is 1333 // different from the claim_value of any heap region before the start of 1334 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1335 // attempting to claim the first region in each chunk, and, if 1336 // successful, applying the closure to each region in the chunk (and 1337 // setting the claim value of the second and subsequent regions of the 1338 // chunk.) For now requires that "doHeapRegion" always returns "false", 1339 // i.e., that a closure never attempt to abort a traversal. 1340 void heap_region_par_iterate_chunked(HeapRegionClosure* cl, 1341 uint worker_id, 1342 uint num_workers, 1343 jint claim_value) const; 1344 1345 // It resets all the region claim values to the default. 1346 void reset_heap_region_claim_values(); 1347 1348 // Resets the claim values of regions in the current 1349 // collection set to the default. 1350 void reset_cset_heap_region_claim_values(); 1351 1352 #ifdef ASSERT 1353 bool check_heap_region_claim_values(jint claim_value); 1354 1355 // Same as the routine above but only checks regions in the 1356 // current collection set. 1357 bool check_cset_heap_region_claim_values(jint claim_value); 1358 #endif // ASSERT 1359 1360 // Clear the cached cset start regions and (more importantly) 1361 // the time stamps. Called when we reset the GC time stamp. 1362 void clear_cset_start_regions(); 1363 1364 // Given the id of a worker, obtain or calculate a suitable 1365 // starting region for iterating over the current collection set. 1366 HeapRegion* start_cset_region_for_worker(uint worker_i); 1367 1368 // Iterate over the regions (if any) in the current collection set. 1369 void collection_set_iterate(HeapRegionClosure* blk); 1370 1371 // As above but starting from region r 1372 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1373 1374 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1375 1376 // A CollectedHeap will contain some number of spaces. This finds the 1377 // space containing a given address, or else returns NULL. 1378 virtual Space* space_containing(const void* addr) const; 1379 1380 // Returns the HeapRegion that contains addr. addr must not be NULL. 1381 template <class T> 1382 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1383 1384 // Returns the HeapRegion that contains addr. addr must not be NULL. 1385 // If addr is within a humongous continues region, it returns its humongous start region. 1386 template <class T> 1387 inline HeapRegion* heap_region_containing(const T addr) const; 1388 1389 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1390 // each address in the (reserved) heap is a member of exactly 1391 // one block. The defining characteristic of a block is that it is 1392 // possible to find its size, and thus to progress forward to the next 1393 // block. (Blocks may be of different sizes.) Thus, blocks may 1394 // represent Java objects, or they might be free blocks in a 1395 // free-list-based heap (or subheap), as long as the two kinds are 1396 // distinguishable and the size of each is determinable. 1397 1398 // Returns the address of the start of the "block" that contains the 1399 // address "addr". We say "blocks" instead of "object" since some heaps 1400 // may not pack objects densely; a chunk may either be an object or a 1401 // non-object. 1402 virtual HeapWord* block_start(const void* addr) const; 1403 1404 // Requires "addr" to be the start of a chunk, and returns its size. 1405 // "addr + size" is required to be the start of a new chunk, or the end 1406 // of the active area of the heap. 1407 virtual size_t block_size(const HeapWord* addr) const; 1408 1409 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1410 // the block is an object. 1411 virtual bool block_is_obj(const HeapWord* addr) const; 1412 1413 // Does this heap support heap inspection? (+PrintClassHistogram) 1414 virtual bool supports_heap_inspection() const { return true; } 1415 1416 // Section on thread-local allocation buffers (TLABs) 1417 // See CollectedHeap for semantics. 1418 1419 bool supports_tlab_allocation() const; 1420 size_t tlab_capacity(Thread* ignored) const; 1421 size_t tlab_used(Thread* ignored) const; 1422 size_t max_tlab_size() const; 1423 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1424 1425 // Can a compiler initialize a new object without store barriers? 1426 // This permission only extends from the creation of a new object 1427 // via a TLAB up to the first subsequent safepoint. If such permission 1428 // is granted for this heap type, the compiler promises to call 1429 // defer_store_barrier() below on any slow path allocation of 1430 // a new object for which such initializing store barriers will 1431 // have been elided. G1, like CMS, allows this, but should be 1432 // ready to provide a compensating write barrier as necessary 1433 // if that storage came out of a non-young region. The efficiency 1434 // of this implementation depends crucially on being able to 1435 // answer very efficiently in constant time whether a piece of 1436 // storage in the heap comes from a young region or not. 1437 // See ReduceInitialCardMarks. 1438 virtual bool can_elide_tlab_store_barriers() const { 1439 return true; 1440 } 1441 1442 virtual bool card_mark_must_follow_store() const { 1443 return true; 1444 } 1445 1446 inline bool is_in_young(const oop obj); 1447 1448 #ifdef ASSERT 1449 virtual bool is_in_partial_collection(const void* p); 1450 #endif 1451 1452 virtual bool is_scavengable(const void* addr); 1453 1454 // We don't need barriers for initializing stores to objects 1455 // in the young gen: for the SATB pre-barrier, there is no 1456 // pre-value that needs to be remembered; for the remembered-set 1457 // update logging post-barrier, we don't maintain remembered set 1458 // information for young gen objects. 1459 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1460 1461 // Returns "true" iff the given word_size is "very large". 1462 static bool isHumongous(size_t word_size) { 1463 // Note this has to be strictly greater-than as the TLABs 1464 // are capped at the humongous thresold and we want to 1465 // ensure that we don't try to allocate a TLAB as 1466 // humongous and that we don't allocate a humongous 1467 // object in a TLAB. 1468 return word_size > _humongous_object_threshold_in_words; 1469 } 1470 1471 // Update mod union table with the set of dirty cards. 1472 void updateModUnion(); 1473 1474 // Set the mod union bits corresponding to the given memRegion. Note 1475 // that this is always a safe operation, since it doesn't clear any 1476 // bits. 1477 void markModUnionRange(MemRegion mr); 1478 1479 // Records the fact that a marking phase is no longer in progress. 1480 void set_marking_complete() { 1481 _mark_in_progress = false; 1482 } 1483 void set_marking_started() { 1484 _mark_in_progress = true; 1485 } 1486 bool mark_in_progress() { 1487 return _mark_in_progress; 1488 } 1489 1490 // Print the maximum heap capacity. 1491 virtual size_t max_capacity() const; 1492 1493 virtual jlong millis_since_last_gc(); 1494 1495 1496 // Convenience function to be used in situations where the heap type can be 1497 // asserted to be this type. 1498 static G1CollectedHeap* heap(); 1499 1500 void set_region_short_lived_locked(HeapRegion* hr); 1501 // add appropriate methods for any other surv rate groups 1502 1503 YoungList* young_list() const { return _young_list; } 1504 1505 // debugging 1506 bool check_young_list_well_formed() { 1507 return _young_list->check_list_well_formed(); 1508 } 1509 1510 bool check_young_list_empty(bool check_heap, 1511 bool check_sample = true); 1512 1513 // *** Stuff related to concurrent marking. It's not clear to me that so 1514 // many of these need to be public. 1515 1516 // The functions below are helper functions that a subclass of 1517 // "CollectedHeap" can use in the implementation of its virtual 1518 // functions. 1519 // This performs a concurrent marking of the live objects in a 1520 // bitmap off to the side. 1521 void doConcurrentMark(); 1522 1523 bool isMarkedPrev(oop obj) const; 1524 bool isMarkedNext(oop obj) const; 1525 1526 // Determine if an object is dead, given the object and also 1527 // the region to which the object belongs. An object is dead 1528 // iff a) it was not allocated since the last mark and b) it 1529 // is not marked. 1530 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1531 return 1532 !hr->obj_allocated_since_prev_marking(obj) && 1533 !isMarkedPrev(obj); 1534 } 1535 1536 // This function returns true when an object has been 1537 // around since the previous marking and hasn't yet 1538 // been marked during this marking. 1539 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1540 return 1541 !hr->obj_allocated_since_next_marking(obj) && 1542 !isMarkedNext(obj); 1543 } 1544 1545 // Determine if an object is dead, given only the object itself. 1546 // This will find the region to which the object belongs and 1547 // then call the region version of the same function. 1548 1549 // Added if it is NULL it isn't dead. 1550 1551 inline bool is_obj_dead(const oop obj) const; 1552 1553 inline bool is_obj_ill(const oop obj) const; 1554 1555 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1556 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1557 bool is_marked(oop obj, VerifyOption vo); 1558 const char* top_at_mark_start_str(VerifyOption vo); 1559 1560 ConcurrentMark* concurrent_mark() const { return _cm; } 1561 1562 // Refinement 1563 1564 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1565 1566 // The dirty cards region list is used to record a subset of regions 1567 // whose cards need clearing. The list if populated during the 1568 // remembered set scanning and drained during the card table 1569 // cleanup. Although the methods are reentrant, population/draining 1570 // phases must not overlap. For synchronization purposes the last 1571 // element on the list points to itself. 1572 HeapRegion* _dirty_cards_region_list; 1573 void push_dirty_cards_region(HeapRegion* hr); 1574 HeapRegion* pop_dirty_cards_region(); 1575 1576 // Optimized nmethod scanning support routines 1577 1578 // Register the given nmethod with the G1 heap 1579 virtual void register_nmethod(nmethod* nm); 1580 1581 // Unregister the given nmethod from the G1 heap 1582 virtual void unregister_nmethod(nmethod* nm); 1583 1584 // Free up superfluous code root memory. 1585 void purge_code_root_memory(); 1586 1587 // Rebuild the stong code root lists for each region 1588 // after a full GC 1589 void rebuild_strong_code_roots(); 1590 1591 // Delete entries for dead interned string and clean up unreferenced symbols 1592 // in symbol table, possibly in parallel. 1593 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1594 1595 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1596 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1597 1598 // Redirty logged cards in the refinement queue. 1599 void redirty_logged_cards(); 1600 // Verification 1601 1602 // The following is just to alert the verification code 1603 // that a full collection has occurred and that the 1604 // remembered sets are no longer up to date. 1605 bool _full_collection; 1606 void set_full_collection() { _full_collection = true;} 1607 void clear_full_collection() {_full_collection = false;} 1608 bool full_collection() {return _full_collection;} 1609 1610 // Perform any cleanup actions necessary before allowing a verification. 1611 virtual void prepare_for_verify(); 1612 1613 // Perform verification. 1614 1615 // vo == UsePrevMarking -> use "prev" marking information, 1616 // vo == UseNextMarking -> use "next" marking information 1617 // vo == UseMarkWord -> use the mark word in the object header 1618 // 1619 // NOTE: Only the "prev" marking information is guaranteed to be 1620 // consistent most of the time, so most calls to this should use 1621 // vo == UsePrevMarking. 1622 // Currently, there is only one case where this is called with 1623 // vo == UseNextMarking, which is to verify the "next" marking 1624 // information at the end of remark. 1625 // Currently there is only one place where this is called with 1626 // vo == UseMarkWord, which is to verify the marking during a 1627 // full GC. 1628 void verify(bool silent, VerifyOption vo); 1629 1630 // Override; it uses the "prev" marking information 1631 virtual void verify(bool silent); 1632 1633 // The methods below are here for convenience and dispatch the 1634 // appropriate method depending on value of the given VerifyOption 1635 // parameter. The values for that parameter, and their meanings, 1636 // are the same as those above. 1637 1638 bool is_obj_dead_cond(const oop obj, 1639 const HeapRegion* hr, 1640 const VerifyOption vo) const; 1641 1642 bool is_obj_dead_cond(const oop obj, 1643 const VerifyOption vo) const; 1644 1645 // Printing 1646 1647 virtual void print_on(outputStream* st) const; 1648 virtual void print_extended_on(outputStream* st) const; 1649 virtual void print_on_error(outputStream* st) const; 1650 1651 virtual void print_gc_threads_on(outputStream* st) const; 1652 virtual void gc_threads_do(ThreadClosure* tc) const; 1653 1654 // Override 1655 void print_tracing_info() const; 1656 1657 // The following two methods are helpful for debugging RSet issues. 1658 void print_cset_rsets() PRODUCT_RETURN; 1659 void print_all_rsets() PRODUCT_RETURN; 1660 1661 public: 1662 size_t pending_card_num(); 1663 size_t cards_scanned(); 1664 1665 protected: 1666 size_t _max_heap_capacity; 1667 }; 1668 1669 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP