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; 189 190 // Closures used in implementation. 191 friend class G1ParScanThreadState; 192 friend class G1ParTask; 193 friend class G1ParGCAllocator; 194 friend class G1PrepareCompactClosure; 195 196 // Other related classes. 197 friend class HeapRegionClaimer; 198 199 private: 200 // The one and only G1CollectedHeap, so static functions can find it. 201 static G1CollectedHeap* _g1h; 202 203 static size_t _humongous_object_threshold_in_words; 204 205 // The secondary free list which contains regions that have been 206 // freed up during the cleanup process. This will be appended to 207 // the master free list when appropriate. 208 FreeRegionList _secondary_free_list; 209 210 // It keeps track of the old regions. 211 HeapRegionSet _old_set; 212 213 // It keeps track of the humongous regions. 214 HeapRegionSet _humongous_set; 215 216 void clear_humongous_is_live_table(); 217 void eagerly_reclaim_humongous_regions(); 218 219 // The number of regions we could create by expansion. 220 uint _expansion_regions; 221 222 // The block offset table for the G1 heap. 223 G1BlockOffsetSharedArray* _bot_shared; 224 225 // Tears down the region sets / lists so that they are empty and the 226 // regions on the heap do not belong to a region set / list. The 227 // only exception is the humongous set which we leave unaltered. If 228 // free_list_only is true, it will only tear down the master free 229 // list. It is called before a Full GC (free_list_only == false) or 230 // before heap shrinking (free_list_only == true). 231 void tear_down_region_sets(bool free_list_only); 232 233 // Rebuilds the region sets / lists so that they are repopulated to 234 // reflect the contents of the heap. The only exception is the 235 // humongous set which was not torn down in the first place. If 236 // free_list_only is true, it will only rebuild the master free 237 // list. It is called after a Full GC (free_list_only == false) or 238 // after heap shrinking (free_list_only == true). 239 void rebuild_region_sets(bool free_list_only); 240 241 // Callback for region mapping changed events. 242 G1RegionMappingChangedListener _listener; 243 244 // The sequence of all heap regions in the heap. 245 HeapRegionManager _hrm; 246 247 // Class that handles the different kinds of allocations. 248 G1Allocator* _allocator; 249 250 // Statistics for each allocation context 251 AllocationContextStats _allocation_context_stats; 252 253 // PLAB sizing policy for survivors. 254 PLABStats _survivor_plab_stats; 255 256 // PLAB sizing policy for tenured objects. 257 PLABStats _old_plab_stats; 258 259 // It specifies whether we should attempt to expand the heap after a 260 // region allocation failure. If heap expansion fails we set this to 261 // false so that we don't re-attempt the heap expansion (it's likely 262 // that subsequent expansion attempts will also fail if one fails). 263 // Currently, it is only consulted during GC and it's reset at the 264 // start of each GC. 265 bool _expand_heap_after_alloc_failure; 266 267 // It resets the mutator alloc region before new allocations can take place. 268 void init_mutator_alloc_region(); 269 270 // It releases the mutator alloc region. 271 void release_mutator_alloc_region(); 272 273 // It initializes the GC alloc regions at the start of a GC. 274 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 275 276 // It releases the GC alloc regions at the end of a GC. 277 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 278 279 // It does any cleanup that needs to be done on the GC alloc regions 280 // before a Full GC. 281 void abandon_gc_alloc_regions(); 282 283 // Helper for monitoring and management support. 284 G1MonitoringSupport* _g1mm; 285 286 // Records whether the region at the given index is kept live by roots or 287 // references from the young generation. 288 class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> { 289 protected: 290 bool default_value() const { return false; } 291 public: 292 void clear() { G1BiasedMappedArray<bool>::clear(); } 293 void set_live(uint region) { 294 set_by_index(region, true); 295 } 296 bool is_live(uint region) { 297 return get_by_index(region); 298 } 299 }; 300 301 HumongousIsLiveBiasedMappedArray _humongous_is_live; 302 // Stores whether during humongous object registration we found candidate regions. 303 // If not, we can skip a few steps. 304 bool _has_humongous_reclaim_candidates; 305 306 volatile unsigned _gc_time_stamp; 307 308 size_t* _surviving_young_words; 309 310 G1HRPrinter _hr_printer; 311 312 void setup_surviving_young_words(); 313 void update_surviving_young_words(size_t* surv_young_words); 314 void cleanup_surviving_young_words(); 315 316 // It decides whether an explicit GC should start a concurrent cycle 317 // instead of doing a STW GC. Currently, a concurrent cycle is 318 // explicitly started if: 319 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 320 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 321 // (c) cause == _g1_humongous_allocation 322 bool should_do_concurrent_full_gc(GCCause::Cause cause); 323 324 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 325 // concurrent cycles) we have started. 326 volatile unsigned int _old_marking_cycles_started; 327 328 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 329 // concurrent cycles) we have completed. 330 volatile unsigned int _old_marking_cycles_completed; 331 332 bool _concurrent_cycle_started; 333 bool _heap_summary_sent; 334 335 // This is a non-product method that is helpful for testing. It is 336 // called at the end of a GC and artificially expands the heap by 337 // allocating a number of dead regions. This way we can induce very 338 // frequent marking cycles and stress the cleanup / concurrent 339 // cleanup code more (as all the regions that will be allocated by 340 // this method will be found dead by the marking cycle). 341 void allocate_dummy_regions() PRODUCT_RETURN; 342 343 // Clear RSets after a compaction. It also resets the GC time stamps. 344 void clear_rsets_post_compaction(); 345 346 // If the HR printer is active, dump the state of the regions in the 347 // heap after a compaction. 348 void print_hrm_post_compaction(); 349 350 double verify(bool guard, const char* msg); 351 void verify_before_gc(); 352 void verify_after_gc(); 353 354 void log_gc_header(); 355 void log_gc_footer(double pause_time_sec); 356 357 // These are macros so that, if the assert fires, we get the correct 358 // line number, file, etc. 359 360 #define heap_locking_asserts_err_msg(_extra_message_) \ 361 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 362 (_extra_message_), \ 363 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 364 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 365 BOOL_TO_STR(Thread::current()->is_VM_thread())) 366 367 #define assert_heap_locked() \ 368 do { \ 369 assert(Heap_lock->owned_by_self(), \ 370 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 371 } while (0) 372 373 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 374 do { \ 375 assert(Heap_lock->owned_by_self() || \ 376 (SafepointSynchronize::is_at_safepoint() && \ 377 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 378 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 379 "should be at a safepoint")); \ 380 } while (0) 381 382 #define assert_heap_locked_and_not_at_safepoint() \ 383 do { \ 384 assert(Heap_lock->owned_by_self() && \ 385 !SafepointSynchronize::is_at_safepoint(), \ 386 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 387 "should not be at a safepoint")); \ 388 } while (0) 389 390 #define assert_heap_not_locked() \ 391 do { \ 392 assert(!Heap_lock->owned_by_self(), \ 393 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 394 } while (0) 395 396 #define assert_heap_not_locked_and_not_at_safepoint() \ 397 do { \ 398 assert(!Heap_lock->owned_by_self() && \ 399 !SafepointSynchronize::is_at_safepoint(), \ 400 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 401 "should not be at a safepoint")); \ 402 } while (0) 403 404 #define assert_at_safepoint(_should_be_vm_thread_) \ 405 do { \ 406 assert(SafepointSynchronize::is_at_safepoint() && \ 407 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 408 heap_locking_asserts_err_msg("should be at a safepoint")); \ 409 } while (0) 410 411 #define assert_not_at_safepoint() \ 412 do { \ 413 assert(!SafepointSynchronize::is_at_safepoint(), \ 414 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 415 } while (0) 416 417 protected: 418 419 // The young region list. 420 YoungList* _young_list; 421 422 // The current policy object for the collector. 423 G1CollectorPolicy* _g1_policy; 424 425 // This is the second level of trying to allocate a new region. If 426 // new_region() didn't find a region on the free_list, this call will 427 // check whether there's anything available on the 428 // secondary_free_list and/or wait for more regions to appear on 429 // that list, if _free_regions_coming is set. 430 HeapRegion* new_region_try_secondary_free_list(bool is_old); 431 432 // Try to allocate a single non-humongous HeapRegion sufficient for 433 // an allocation of the given word_size. If do_expand is true, 434 // attempt to expand the heap if necessary to satisfy the allocation 435 // request. If the region is to be used as an old region or for a 436 // humongous object, set is_old to true. If not, to false. 437 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 438 439 // Initialize a contiguous set of free regions of length num_regions 440 // and starting at index first so that they appear as a single 441 // humongous region. 442 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 443 uint num_regions, 444 size_t word_size, 445 AllocationContext_t context); 446 447 // Attempt to allocate a humongous object of the given size. Return 448 // NULL if unsuccessful. 449 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 450 451 // The following two methods, allocate_new_tlab() and 452 // mem_allocate(), are the two main entry points from the runtime 453 // into the G1's allocation routines. They have the following 454 // assumptions: 455 // 456 // * They should both be called outside safepoints. 457 // 458 // * They should both be called without holding the Heap_lock. 459 // 460 // * All allocation requests for new TLABs should go to 461 // allocate_new_tlab(). 462 // 463 // * All non-TLAB allocation requests should go to mem_allocate(). 464 // 465 // * If either call cannot satisfy the allocation request using the 466 // current allocating region, they will try to get a new one. If 467 // this fails, they will attempt to do an evacuation pause and 468 // retry the allocation. 469 // 470 // * If all allocation attempts fail, even after trying to schedule 471 // an evacuation pause, allocate_new_tlab() will return NULL, 472 // whereas mem_allocate() will attempt a heap expansion and/or 473 // schedule a Full GC. 474 // 475 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 476 // should never be called with word_size being humongous. All 477 // humongous allocation requests should go to mem_allocate() which 478 // will satisfy them with a special path. 479 480 virtual HeapWord* allocate_new_tlab(size_t word_size); 481 482 virtual HeapWord* mem_allocate(size_t word_size, 483 bool* gc_overhead_limit_was_exceeded); 484 485 // The following three methods take a gc_count_before_ret 486 // parameter which is used to return the GC count if the method 487 // returns NULL. Given that we are required to read the GC count 488 // while holding the Heap_lock, and these paths will take the 489 // Heap_lock at some point, it's easier to get them to read the GC 490 // count while holding the Heap_lock before they return NULL instead 491 // of the caller (namely: mem_allocate()) having to also take the 492 // Heap_lock just to read the GC count. 493 494 // First-level mutator allocation attempt: try to allocate out of 495 // the mutator alloc region without taking the Heap_lock. This 496 // should only be used for non-humongous allocations. 497 inline HeapWord* attempt_allocation(size_t word_size, 498 unsigned int* gc_count_before_ret, 499 int* gclocker_retry_count_ret); 500 501 // Second-level mutator allocation attempt: take the Heap_lock and 502 // retry the allocation attempt, potentially scheduling a GC 503 // pause. This should only be used for non-humongous allocations. 504 HeapWord* attempt_allocation_slow(size_t word_size, 505 AllocationContext_t context, 506 unsigned int* gc_count_before_ret, 507 int* gclocker_retry_count_ret); 508 509 // Takes the Heap_lock and attempts a humongous allocation. It can 510 // potentially schedule a GC pause. 511 HeapWord* attempt_allocation_humongous(size_t word_size, 512 unsigned int* gc_count_before_ret, 513 int* gclocker_retry_count_ret); 514 515 // Allocation attempt that should be called during safepoints (e.g., 516 // at the end of a successful GC). expect_null_mutator_alloc_region 517 // specifies whether the mutator alloc region is expected to be NULL 518 // or not. 519 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 520 AllocationContext_t context, 521 bool expect_null_mutator_alloc_region); 522 523 // It dirties the cards that cover the block so that so that the post 524 // write barrier never queues anything when updating objects on this 525 // block. It is assumed (and in fact we assert) that the block 526 // belongs to a young region. 527 inline void dirty_young_block(HeapWord* start, size_t word_size); 528 529 // Allocate blocks during garbage collection. Will ensure an 530 // allocation region, either by picking one or expanding the 531 // heap, and then allocate a block of the given size. The block 532 // may not be a humongous - it must fit into a single heap region. 533 inline HeapWord* par_allocate_during_gc(InCSetState dest, 534 size_t word_size, 535 AllocationContext_t context); 536 // Ensure that no further allocations can happen in "r", bearing in mind 537 // that parallel threads might be attempting allocations. 538 void par_allocate_remaining_space(HeapRegion* r); 539 540 // Allocation attempt during GC for a survivor object / PLAB. 541 inline HeapWord* survivor_attempt_allocation(size_t word_size, 542 AllocationContext_t context); 543 544 // Allocation attempt during GC for an old object / PLAB. 545 inline HeapWord* old_attempt_allocation(size_t word_size, 546 AllocationContext_t context); 547 548 // These methods are the "callbacks" from the G1AllocRegion class. 549 550 // For mutator alloc regions. 551 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 552 void retire_mutator_alloc_region(HeapRegion* alloc_region, 553 size_t allocated_bytes); 554 555 // For GC alloc regions. 556 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 557 InCSetState dest); 558 void retire_gc_alloc_region(HeapRegion* alloc_region, 559 size_t allocated_bytes, InCSetState dest); 560 561 // - if explicit_gc is true, the GC is for a System.gc() or a heap 562 // inspection request and should collect the entire heap 563 // - if clear_all_soft_refs is true, all soft references should be 564 // cleared during the GC 565 // - if explicit_gc is false, word_size describes the allocation that 566 // the GC should attempt (at least) to satisfy 567 // - it returns false if it is unable to do the collection due to the 568 // GC locker being active, true otherwise 569 bool do_collection(bool explicit_gc, 570 bool clear_all_soft_refs, 571 size_t word_size); 572 573 // Callback from VM_G1CollectFull operation. 574 // Perform a full collection. 575 virtual void do_full_collection(bool clear_all_soft_refs); 576 577 // Resize the heap if necessary after a full collection. If this is 578 // after a collect-for allocation, "word_size" is the allocation size, 579 // and will be considered part of the used portion of the heap. 580 void resize_if_necessary_after_full_collection(size_t word_size); 581 582 // Callback from VM_G1CollectForAllocation operation. 583 // This function does everything necessary/possible to satisfy a 584 // failed allocation request (including collection, expansion, etc.) 585 HeapWord* satisfy_failed_allocation(size_t word_size, 586 AllocationContext_t context, 587 bool* succeeded); 588 589 // Attempting to expand the heap sufficiently 590 // to support an allocation of the given "word_size". If 591 // successful, perform the allocation and return the address of the 592 // allocated block, or else "NULL". 593 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 594 595 // Process any reference objects discovered during 596 // an incremental evacuation pause. 597 void process_discovered_references(uint no_of_gc_workers); 598 599 // Enqueue any remaining discovered references 600 // after processing. 601 void enqueue_discovered_references(uint no_of_gc_workers); 602 603 public: 604 605 G1Allocator* allocator() { 606 return _allocator; 607 } 608 609 G1MonitoringSupport* g1mm() { 610 assert(_g1mm != NULL, "should have been initialized"); 611 return _g1mm; 612 } 613 614 // Expand the garbage-first heap by at least the given size (in bytes!). 615 // Returns true if the heap was expanded by the requested amount; 616 // false otherwise. 617 // (Rounds up to a HeapRegion boundary.) 618 bool expand(size_t expand_bytes); 619 620 // Returns the PLAB statistics for a given destination. 621 inline PLABStats* alloc_buffer_stats(InCSetState dest); 622 623 // Determines PLAB size for a given destination. 624 inline size_t desired_plab_sz(InCSetState dest); 625 626 inline AllocationContextStats& allocation_context_stats(); 627 628 // Do anything common to GC's. 629 virtual void gc_prologue(bool full); 630 virtual void gc_epilogue(bool full); 631 632 inline void set_humongous_is_live(oop obj); 633 634 bool humongous_is_live(uint region) { 635 return _humongous_is_live.is_live(region); 636 } 637 638 // Returns whether the given region (which must be a humongous (start) region) 639 // is to be considered conservatively live regardless of any other conditions. 640 bool humongous_region_is_always_live(uint index); 641 // Register the given region to be part of the collection set. 642 inline void register_humongous_region_with_in_cset_fast_test(uint index); 643 // Register regions with humongous objects (actually on the start region) in 644 // the in_cset_fast_test table. 645 void register_humongous_regions_with_in_cset_fast_test(); 646 // We register a region with the fast "in collection set" test. We 647 // simply set to true the array slot corresponding to this region. 648 void register_young_region_with_in_cset_fast_test(HeapRegion* r) { 649 _in_cset_fast_test.set_in_young(r->hrm_index()); 650 } 651 void register_old_region_with_in_cset_fast_test(HeapRegion* r) { 652 _in_cset_fast_test.set_in_old(r->hrm_index()); 653 } 654 655 // This is a fast test on whether a reference points into the 656 // collection set or not. Assume that the reference 657 // points into the heap. 658 inline bool in_cset_fast_test(oop obj); 659 660 void clear_cset_fast_test() { 661 _in_cset_fast_test.clear(); 662 } 663 664 // This is called at the start of either a concurrent cycle or a Full 665 // GC to update the number of old marking cycles started. 666 void increment_old_marking_cycles_started(); 667 668 // This is called at the end of either a concurrent cycle or a Full 669 // GC to update the number of old marking cycles completed. Those two 670 // can happen in a nested fashion, i.e., we start a concurrent 671 // cycle, a Full GC happens half-way through it which ends first, 672 // and then the cycle notices that a Full GC happened and ends 673 // too. The concurrent parameter is a boolean to help us do a bit 674 // tighter consistency checking in the method. If concurrent is 675 // false, the caller is the inner caller in the nesting (i.e., the 676 // Full GC). If concurrent is true, the caller is the outer caller 677 // in this nesting (i.e., the concurrent cycle). Further nesting is 678 // not currently supported. The end of this call also notifies 679 // the FullGCCount_lock in case a Java thread is waiting for a full 680 // GC to happen (e.g., it called System.gc() with 681 // +ExplicitGCInvokesConcurrent). 682 void increment_old_marking_cycles_completed(bool concurrent); 683 684 unsigned int old_marking_cycles_completed() { 685 return _old_marking_cycles_completed; 686 } 687 688 void register_concurrent_cycle_start(const Ticks& start_time); 689 void register_concurrent_cycle_end(); 690 void trace_heap_after_concurrent_cycle(); 691 692 G1YCType yc_type(); 693 694 G1HRPrinter* hr_printer() { return &_hr_printer; } 695 696 // Frees a non-humongous region by initializing its contents and 697 // adding it to the free list that's passed as a parameter (this is 698 // usually a local list which will be appended to the master free 699 // list later). The used bytes of freed regions are accumulated in 700 // pre_used. If par is true, the region's RSet will not be freed 701 // up. The assumption is that this will be done later. 702 // The locked parameter indicates if the caller has already taken 703 // care of proper synchronization. This may allow some optimizations. 704 void free_region(HeapRegion* hr, 705 FreeRegionList* free_list, 706 bool par, 707 bool locked = false); 708 709 // Frees a humongous region by collapsing it into individual regions 710 // and calling free_region() for each of them. The freed regions 711 // will be added to the free list that's passed as a parameter (this 712 // is usually a local list which will be appended to the master free 713 // list later). The used bytes of freed regions are accumulated in 714 // pre_used. If par is true, the region's RSet will not be freed 715 // up. The assumption is that this will be done later. 716 void free_humongous_region(HeapRegion* hr, 717 FreeRegionList* free_list, 718 bool par); 719 protected: 720 721 // Shrink the garbage-first heap by at most the given size (in bytes!). 722 // (Rounds down to a HeapRegion boundary.) 723 virtual void shrink(size_t expand_bytes); 724 void shrink_helper(size_t expand_bytes); 725 726 #if TASKQUEUE_STATS 727 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 728 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 729 void reset_taskqueue_stats(); 730 #endif // TASKQUEUE_STATS 731 732 // Schedule the VM operation that will do an evacuation pause to 733 // satisfy an allocation request of word_size. *succeeded will 734 // return whether the VM operation was successful (it did do an 735 // evacuation pause) or not (another thread beat us to it or the GC 736 // locker was active). Given that we should not be holding the 737 // Heap_lock when we enter this method, we will pass the 738 // gc_count_before (i.e., total_collections()) as a parameter since 739 // it has to be read while holding the Heap_lock. Currently, both 740 // methods that call do_collection_pause() release the Heap_lock 741 // before the call, so it's easy to read gc_count_before just before. 742 HeapWord* do_collection_pause(size_t word_size, 743 unsigned int gc_count_before, 744 bool* succeeded, 745 GCCause::Cause gc_cause); 746 747 // The guts of the incremental collection pause, executed by the vm 748 // thread. It returns false if it is unable to do the collection due 749 // to the GC locker being active, true otherwise 750 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 751 752 // Actually do the work of evacuating the collection set. 753 void evacuate_collection_set(EvacuationInfo& evacuation_info); 754 755 // The g1 remembered set of the heap. 756 G1RemSet* _g1_rem_set; 757 758 // A set of cards that cover the objects for which the Rsets should be updated 759 // concurrently after the collection. 760 DirtyCardQueueSet _dirty_card_queue_set; 761 762 // The closure used to refine a single card. 763 RefineCardTableEntryClosure* _refine_cte_cl; 764 765 // A DirtyCardQueueSet that is used to hold cards that contain 766 // references into the current collection set. This is used to 767 // update the remembered sets of the regions in the collection 768 // set in the event of an evacuation failure. 769 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 770 771 // After a collection pause, make the regions in the CS into free 772 // regions. 773 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 774 775 // Abandon the current collection set without recording policy 776 // statistics or updating free lists. 777 void abandon_collection_set(HeapRegion* cs_head); 778 779 // Applies "scan_non_heap_roots" to roots outside the heap, 780 // "scan_rs" to roots inside the heap (having done "set_region" to 781 // indicate the region in which the root resides), 782 // and does "scan_metadata" If "scan_rs" is 783 // NULL, then this step is skipped. The "worker_i" 784 // param is for use with parallel roots processing, and should be 785 // the "i" of the calling parallel worker thread's work(i) function. 786 // In the sequential case this param will be ignored. 787 void g1_process_roots(OopClosure* scan_non_heap_roots, 788 OopClosure* scan_non_heap_weak_roots, 789 G1ParPushHeapRSClosure* scan_rs, 790 CLDClosure* scan_strong_clds, 791 CLDClosure* scan_weak_clds, 792 CodeBlobClosure* scan_strong_code, 793 uint worker_i); 794 795 // The concurrent marker (and the thread it runs in.) 796 ConcurrentMark* _cm; 797 ConcurrentMarkThread* _cmThread; 798 bool _mark_in_progress; 799 800 // The concurrent refiner. 801 ConcurrentG1Refine* _cg1r; 802 803 // The parallel task queues 804 RefToScanQueueSet *_task_queues; 805 806 // True iff a evacuation has failed in the current collection. 807 bool _evacuation_failed; 808 809 EvacuationFailedInfo* _evacuation_failed_info_array; 810 811 // Failed evacuations cause some logical from-space objects to have 812 // forwarding pointers to themselves. Reset them. 813 void remove_self_forwarding_pointers(); 814 815 // Together, these store an object with a preserved mark, and its mark value. 816 Stack<oop, mtGC> _objs_with_preserved_marks; 817 Stack<markOop, mtGC> _preserved_marks_of_objs; 818 819 // Preserve the mark of "obj", if necessary, in preparation for its mark 820 // word being overwritten with a self-forwarding-pointer. 821 void preserve_mark_if_necessary(oop obj, markOop m); 822 823 // The stack of evac-failure objects left to be scanned. 824 GrowableArray<oop>* _evac_failure_scan_stack; 825 // The closure to apply to evac-failure objects. 826 827 OopsInHeapRegionClosure* _evac_failure_closure; 828 // Set the field above. 829 void 830 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 831 _evac_failure_closure = evac_failure_closure; 832 } 833 834 // Push "obj" on the scan stack. 835 void push_on_evac_failure_scan_stack(oop obj); 836 // Process scan stack entries until the stack is empty. 837 void drain_evac_failure_scan_stack(); 838 // True iff an invocation of "drain_scan_stack" is in progress; to 839 // prevent unnecessary recursion. 840 bool _drain_in_progress; 841 842 // Do any necessary initialization for evacuation-failure handling. 843 // "cl" is the closure that will be used to process evac-failure 844 // objects. 845 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 846 // Do any necessary cleanup for evacuation-failure handling data 847 // structures. 848 void finalize_for_evac_failure(); 849 850 // An attempt to evacuate "obj" has failed; take necessary steps. 851 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 852 void handle_evacuation_failure_common(oop obj, markOop m); 853 854 #ifndef PRODUCT 855 // Support for forcing evacuation failures. Analogous to 856 // PromotionFailureALot for the other collectors. 857 858 // Records whether G1EvacuationFailureALot should be in effect 859 // for the current GC 860 bool _evacuation_failure_alot_for_current_gc; 861 862 // Used to record the GC number for interval checking when 863 // determining whether G1EvaucationFailureALot is in effect 864 // for the current GC. 865 size_t _evacuation_failure_alot_gc_number; 866 867 // Count of the number of evacuations between failures. 868 volatile size_t _evacuation_failure_alot_count; 869 870 // Set whether G1EvacuationFailureALot should be in effect 871 // for the current GC (based upon the type of GC and which 872 // command line flags are set); 873 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 874 bool during_initial_mark, 875 bool during_marking); 876 877 inline void set_evacuation_failure_alot_for_current_gc(); 878 879 // Return true if it's time to cause an evacuation failure. 880 inline bool evacuation_should_fail(); 881 882 // Reset the G1EvacuationFailureALot counters. Should be called at 883 // the end of an evacuation pause in which an evacuation failure occurred. 884 inline void reset_evacuation_should_fail(); 885 #endif // !PRODUCT 886 887 // ("Weak") Reference processing support. 888 // 889 // G1 has 2 instances of the reference processor class. One 890 // (_ref_processor_cm) handles reference object discovery 891 // and subsequent processing during concurrent marking cycles. 892 // 893 // The other (_ref_processor_stw) handles reference object 894 // discovery and processing during full GCs and incremental 895 // evacuation pauses. 896 // 897 // During an incremental pause, reference discovery will be 898 // temporarily disabled for _ref_processor_cm and will be 899 // enabled for _ref_processor_stw. At the end of the evacuation 900 // pause references discovered by _ref_processor_stw will be 901 // processed and discovery will be disabled. The previous 902 // setting for reference object discovery for _ref_processor_cm 903 // will be re-instated. 904 // 905 // At the start of marking: 906 // * Discovery by the CM ref processor is verified to be inactive 907 // and it's discovered lists are empty. 908 // * Discovery by the CM ref processor is then enabled. 909 // 910 // At the end of marking: 911 // * Any references on the CM ref processor's discovered 912 // lists are processed (possibly MT). 913 // 914 // At the start of full GC we: 915 // * Disable discovery by the CM ref processor and 916 // empty CM ref processor's discovered lists 917 // (without processing any entries). 918 // * Verify that the STW ref processor is inactive and it's 919 // discovered lists are empty. 920 // * Temporarily set STW ref processor discovery as single threaded. 921 // * Temporarily clear the STW ref processor's _is_alive_non_header 922 // field. 923 // * Finally enable discovery by the STW ref processor. 924 // 925 // The STW ref processor is used to record any discovered 926 // references during the full GC. 927 // 928 // At the end of a full GC we: 929 // * Enqueue any reference objects discovered by the STW ref processor 930 // that have non-live referents. This has the side-effect of 931 // making the STW ref processor inactive by disabling discovery. 932 // * Verify that the CM ref processor is still inactive 933 // and no references have been placed on it's discovered 934 // lists (also checked as a precondition during initial marking). 935 936 // The (stw) reference processor... 937 ReferenceProcessor* _ref_processor_stw; 938 939 STWGCTimer* _gc_timer_stw; 940 ConcurrentGCTimer* _gc_timer_cm; 941 942 G1OldTracer* _gc_tracer_cm; 943 G1NewTracer* _gc_tracer_stw; 944 945 // During reference object discovery, the _is_alive_non_header 946 // closure (if non-null) is applied to the referent object to 947 // determine whether the referent is live. If so then the 948 // reference object does not need to be 'discovered' and can 949 // be treated as a regular oop. This has the benefit of reducing 950 // the number of 'discovered' reference objects that need to 951 // be processed. 952 // 953 // Instance of the is_alive closure for embedding into the 954 // STW reference processor as the _is_alive_non_header field. 955 // Supplying a value for the _is_alive_non_header field is 956 // optional but doing so prevents unnecessary additions to 957 // the discovered lists during reference discovery. 958 G1STWIsAliveClosure _is_alive_closure_stw; 959 960 // The (concurrent marking) reference processor... 961 ReferenceProcessor* _ref_processor_cm; 962 963 // Instance of the concurrent mark is_alive closure for embedding 964 // into the Concurrent Marking reference processor as the 965 // _is_alive_non_header field. Supplying a value for the 966 // _is_alive_non_header field is optional but doing so prevents 967 // unnecessary additions to the discovered lists during reference 968 // discovery. 969 G1CMIsAliveClosure _is_alive_closure_cm; 970 971 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 972 HeapRegion** _worker_cset_start_region; 973 974 // Time stamp to validate the regions recorded in the cache 975 // used by G1CollectedHeap::start_cset_region_for_worker(). 976 // The heap region entry for a given worker is valid iff 977 // the associated time stamp value matches the current value 978 // of G1CollectedHeap::_gc_time_stamp. 979 unsigned int* _worker_cset_start_region_time_stamp; 980 981 enum G1H_process_roots_tasks { 982 G1H_PS_filter_satb_buffers, 983 G1H_PS_refProcessor_oops_do, 984 // Leave this one last. 985 G1H_PS_NumElements 986 }; 987 988 SubTasksDone* _process_strong_tasks; 989 990 volatile bool _free_regions_coming; 991 992 public: 993 994 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 995 996 void set_refine_cte_cl_concurrency(bool concurrent); 997 998 RefToScanQueue *task_queue(int i) const; 999 1000 // A set of cards where updates happened during the GC 1001 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1002 1003 // A DirtyCardQueueSet that is used to hold cards that contain 1004 // references into the current collection set. This is used to 1005 // update the remembered sets of the regions in the collection 1006 // set in the event of an evacuation failure. 1007 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1008 { return _into_cset_dirty_card_queue_set; } 1009 1010 // Create a G1CollectedHeap with the specified policy. 1011 // Must call the initialize method afterwards. 1012 // May not return if something goes wrong. 1013 G1CollectedHeap(G1CollectorPolicy* policy); 1014 1015 // Initialize the G1CollectedHeap to have the initial and 1016 // maximum sizes and remembered and barrier sets 1017 // specified by the policy object. 1018 jint initialize(); 1019 1020 virtual void stop(); 1021 1022 // Return the (conservative) maximum heap alignment for any G1 heap 1023 static size_t conservative_max_heap_alignment(); 1024 1025 // Initialize weak reference processing. 1026 virtual void ref_processing_init(); 1027 1028 void set_par_threads(uint t) { 1029 SharedHeap::set_par_threads(t); 1030 // Done in SharedHeap but oddly there are 1031 // two _process_strong_tasks's in a G1CollectedHeap 1032 // so do it here too. 1033 _process_strong_tasks->set_n_threads(t); 1034 } 1035 1036 // Set _n_par_threads according to a policy TBD. 1037 void set_par_threads(); 1038 1039 void set_n_termination(int t) { 1040 _process_strong_tasks->set_n_threads(t); 1041 } 1042 1043 virtual CollectedHeap::Name kind() const { 1044 return CollectedHeap::G1CollectedHeap; 1045 } 1046 1047 // The current policy object for the collector. 1048 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1049 1050 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1051 1052 // Adaptive size policy. No such thing for g1. 1053 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1054 1055 // The rem set and barrier set. 1056 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1057 1058 unsigned get_gc_time_stamp() { 1059 return _gc_time_stamp; 1060 } 1061 1062 inline void reset_gc_time_stamp(); 1063 1064 void check_gc_time_stamps() PRODUCT_RETURN; 1065 1066 inline void increment_gc_time_stamp(); 1067 1068 // Reset the given region's GC timestamp. If it's starts humongous, 1069 // also reset the GC timestamp of its corresponding 1070 // continues humongous regions too. 1071 void reset_gc_time_stamps(HeapRegion* hr); 1072 1073 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1074 DirtyCardQueue* into_cset_dcq, 1075 bool concurrent, uint worker_i); 1076 1077 // The shared block offset table array. 1078 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1079 1080 // Reference Processing accessors 1081 1082 // The STW reference processor.... 1083 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1084 1085 // The Concurrent Marking reference processor... 1086 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1087 1088 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1089 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1090 1091 virtual size_t capacity() const; 1092 virtual size_t used() const; 1093 // This should be called when we're not holding the heap lock. The 1094 // result might be a bit inaccurate. 1095 size_t used_unlocked() const; 1096 size_t recalculate_used() const; 1097 1098 // These virtual functions do the actual allocation. 1099 // Some heaps may offer a contiguous region for shared non-blocking 1100 // allocation, via inlined code (by exporting the address of the top and 1101 // end fields defining the extent of the contiguous allocation region.) 1102 // But G1CollectedHeap doesn't yet support this. 1103 1104 virtual bool is_maximal_no_gc() const { 1105 return _hrm.available() == 0; 1106 } 1107 1108 // The current number of regions in the heap. 1109 uint num_regions() const { return _hrm.length(); } 1110 1111 // The max number of regions in the heap. 1112 uint max_regions() const { return _hrm.max_length(); } 1113 1114 // The number of regions that are completely free. 1115 uint num_free_regions() const { return _hrm.num_free_regions(); } 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 // Iterate over the heap regions in parallel. Assumes that this will be called 1309 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1310 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1311 // to each of the regions, by attempting to claim the region using the 1312 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1313 // region. The concurrent argument should be set to true if iteration is 1314 // performed concurrently, during which no assumptions are made for consistent 1315 // attributes of the heap regions (as they might be modified while iterating). 1316 void heap_region_par_iterate(HeapRegionClosure* cl, 1317 uint worker_id, 1318 HeapRegionClaimer* hrclaimer, 1319 bool concurrent = false) const; 1320 1321 // Clear the cached cset start regions and (more importantly) 1322 // the time stamps. Called when we reset the GC time stamp. 1323 void clear_cset_start_regions(); 1324 1325 // Given the id of a worker, obtain or calculate a suitable 1326 // starting region for iterating over the current collection set. 1327 HeapRegion* start_cset_region_for_worker(uint worker_i); 1328 1329 // Iterate over the regions (if any) in the current collection set. 1330 void collection_set_iterate(HeapRegionClosure* blk); 1331 1332 // As above but starting from region r 1333 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1334 1335 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1336 1337 // A CollectedHeap will contain some number of spaces. This finds the 1338 // space containing a given address, or else returns NULL. 1339 virtual Space* space_containing(const void* addr) const; 1340 1341 // Returns the HeapRegion that contains addr. addr must not be NULL. 1342 template <class T> 1343 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1344 1345 // Returns the HeapRegion that contains addr. addr must not be NULL. 1346 // If addr is within a humongous continues region, it returns its humongous start region. 1347 template <class T> 1348 inline HeapRegion* heap_region_containing(const T addr) const; 1349 1350 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1351 // each address in the (reserved) heap is a member of exactly 1352 // one block. The defining characteristic of a block is that it is 1353 // possible to find its size, and thus to progress forward to the next 1354 // block. (Blocks may be of different sizes.) Thus, blocks may 1355 // represent Java objects, or they might be free blocks in a 1356 // free-list-based heap (or subheap), as long as the two kinds are 1357 // distinguishable and the size of each is determinable. 1358 1359 // Returns the address of the start of the "block" that contains the 1360 // address "addr". We say "blocks" instead of "object" since some heaps 1361 // may not pack objects densely; a chunk may either be an object or a 1362 // non-object. 1363 virtual HeapWord* block_start(const void* addr) const; 1364 1365 // Requires "addr" to be the start of a chunk, and returns its size. 1366 // "addr + size" is required to be the start of a new chunk, or the end 1367 // of the active area of the heap. 1368 virtual size_t block_size(const HeapWord* addr) const; 1369 1370 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1371 // the block is an object. 1372 virtual bool block_is_obj(const HeapWord* addr) const; 1373 1374 // Does this heap support heap inspection? (+PrintClassHistogram) 1375 virtual bool supports_heap_inspection() const { return true; } 1376 1377 // Section on thread-local allocation buffers (TLABs) 1378 // See CollectedHeap for semantics. 1379 1380 bool supports_tlab_allocation() const; 1381 size_t tlab_capacity(Thread* ignored) const; 1382 size_t tlab_used(Thread* ignored) const; 1383 size_t max_tlab_size() const; 1384 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1385 1386 // Can a compiler initialize a new object without store barriers? 1387 // This permission only extends from the creation of a new object 1388 // via a TLAB up to the first subsequent safepoint. If such permission 1389 // is granted for this heap type, the compiler promises to call 1390 // defer_store_barrier() below on any slow path allocation of 1391 // a new object for which such initializing store barriers will 1392 // have been elided. G1, like CMS, allows this, but should be 1393 // ready to provide a compensating write barrier as necessary 1394 // if that storage came out of a non-young region. The efficiency 1395 // of this implementation depends crucially on being able to 1396 // answer very efficiently in constant time whether a piece of 1397 // storage in the heap comes from a young region or not. 1398 // See ReduceInitialCardMarks. 1399 virtual bool can_elide_tlab_store_barriers() const { 1400 return true; 1401 } 1402 1403 virtual bool card_mark_must_follow_store() const { 1404 return true; 1405 } 1406 1407 inline bool is_in_young(const oop obj); 1408 1409 #ifdef ASSERT 1410 virtual bool is_in_partial_collection(const void* p); 1411 #endif 1412 1413 virtual bool is_scavengable(const void* addr); 1414 1415 // We don't need barriers for initializing stores to objects 1416 // in the young gen: for the SATB pre-barrier, there is no 1417 // pre-value that needs to be remembered; for the remembered-set 1418 // update logging post-barrier, we don't maintain remembered set 1419 // information for young gen objects. 1420 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1421 1422 // Returns "true" iff the given word_size is "very large". 1423 static bool is_humongous(size_t word_size) { 1424 // Note this has to be strictly greater-than as the TLABs 1425 // are capped at the humongous threshold and we want to 1426 // ensure that we don't try to allocate a TLAB as 1427 // humongous and that we don't allocate a humongous 1428 // object in a TLAB. 1429 return word_size > _humongous_object_threshold_in_words; 1430 } 1431 1432 // Update mod union table with the set of dirty cards. 1433 void updateModUnion(); 1434 1435 // Set the mod union bits corresponding to the given memRegion. Note 1436 // that this is always a safe operation, since it doesn't clear any 1437 // bits. 1438 void markModUnionRange(MemRegion mr); 1439 1440 // Records the fact that a marking phase is no longer in progress. 1441 void set_marking_complete() { 1442 _mark_in_progress = false; 1443 } 1444 void set_marking_started() { 1445 _mark_in_progress = true; 1446 } 1447 bool mark_in_progress() { 1448 return _mark_in_progress; 1449 } 1450 1451 // Print the maximum heap capacity. 1452 virtual size_t max_capacity() const; 1453 1454 virtual jlong millis_since_last_gc(); 1455 1456 1457 // Convenience function to be used in situations where the heap type can be 1458 // asserted to be this type. 1459 static G1CollectedHeap* heap(); 1460 1461 void set_region_short_lived_locked(HeapRegion* hr); 1462 // add appropriate methods for any other surv rate groups 1463 1464 YoungList* young_list() const { return _young_list; } 1465 1466 // debugging 1467 bool check_young_list_well_formed() { 1468 return _young_list->check_list_well_formed(); 1469 } 1470 1471 bool check_young_list_empty(bool check_heap, 1472 bool check_sample = true); 1473 1474 // *** Stuff related to concurrent marking. It's not clear to me that so 1475 // many of these need to be public. 1476 1477 // The functions below are helper functions that a subclass of 1478 // "CollectedHeap" can use in the implementation of its virtual 1479 // functions. 1480 // This performs a concurrent marking of the live objects in a 1481 // bitmap off to the side. 1482 void doConcurrentMark(); 1483 1484 bool isMarkedPrev(oop obj) const; 1485 bool isMarkedNext(oop obj) const; 1486 1487 // Determine if an object is dead, given the object and also 1488 // the region to which the object belongs. An object is dead 1489 // iff a) it was not allocated since the last mark and b) it 1490 // is not marked. 1491 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1492 return 1493 !hr->obj_allocated_since_prev_marking(obj) && 1494 !isMarkedPrev(obj); 1495 } 1496 1497 // This function returns true when an object has been 1498 // around since the previous marking and hasn't yet 1499 // been marked during this marking. 1500 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1501 return 1502 !hr->obj_allocated_since_next_marking(obj) && 1503 !isMarkedNext(obj); 1504 } 1505 1506 // Determine if an object is dead, given only the object itself. 1507 // This will find the region to which the object belongs and 1508 // then call the region version of the same function. 1509 1510 // Added if it is NULL it isn't dead. 1511 1512 inline bool is_obj_dead(const oop obj) const; 1513 1514 inline bool is_obj_ill(const oop obj) const; 1515 1516 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1517 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1518 bool is_marked(oop obj, VerifyOption vo); 1519 const char* top_at_mark_start_str(VerifyOption vo); 1520 1521 ConcurrentMark* concurrent_mark() const { return _cm; } 1522 1523 // Refinement 1524 1525 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1526 1527 // The dirty cards region list is used to record a subset of regions 1528 // whose cards need clearing. The list if populated during the 1529 // remembered set scanning and drained during the card table 1530 // cleanup. Although the methods are reentrant, population/draining 1531 // phases must not overlap. For synchronization purposes the last 1532 // element on the list points to itself. 1533 HeapRegion* _dirty_cards_region_list; 1534 void push_dirty_cards_region(HeapRegion* hr); 1535 HeapRegion* pop_dirty_cards_region(); 1536 1537 // Optimized nmethod scanning support routines 1538 1539 // Register the given nmethod with the G1 heap. 1540 virtual void register_nmethod(nmethod* nm); 1541 1542 // Unregister the given nmethod from the G1 heap. 1543 virtual void unregister_nmethod(nmethod* nm); 1544 1545 // Free up superfluous code root memory. 1546 void purge_code_root_memory(); 1547 1548 // Rebuild the strong code root lists for each region 1549 // after a full GC. 1550 void rebuild_strong_code_roots(); 1551 1552 // Delete entries for dead interned string and clean up unreferenced symbols 1553 // in symbol table, possibly in parallel. 1554 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1555 1556 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1557 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1558 1559 // Redirty logged cards in the refinement queue. 1560 void redirty_logged_cards(); 1561 // Verification 1562 1563 // The following is just to alert the verification code 1564 // that a full collection has occurred and that the 1565 // remembered sets are no longer up to date. 1566 bool _full_collection; 1567 void set_full_collection() { _full_collection = true;} 1568 void clear_full_collection() {_full_collection = false;} 1569 bool full_collection() {return _full_collection;} 1570 1571 // Perform any cleanup actions necessary before allowing a verification. 1572 virtual void prepare_for_verify(); 1573 1574 // Perform verification. 1575 1576 // vo == UsePrevMarking -> use "prev" marking information, 1577 // vo == UseNextMarking -> use "next" marking information 1578 // vo == UseMarkWord -> use the mark word in the object header 1579 // 1580 // NOTE: Only the "prev" marking information is guaranteed to be 1581 // consistent most of the time, so most calls to this should use 1582 // vo == UsePrevMarking. 1583 // Currently, there is only one case where this is called with 1584 // vo == UseNextMarking, which is to verify the "next" marking 1585 // information at the end of remark. 1586 // Currently there is only one place where this is called with 1587 // vo == UseMarkWord, which is to verify the marking during a 1588 // full GC. 1589 void verify(bool silent, VerifyOption vo); 1590 1591 // Override; it uses the "prev" marking information 1592 virtual void verify(bool silent); 1593 1594 // The methods below are here for convenience and dispatch the 1595 // appropriate method depending on value of the given VerifyOption 1596 // parameter. The values for that parameter, and their meanings, 1597 // are the same as those above. 1598 1599 bool is_obj_dead_cond(const oop obj, 1600 const HeapRegion* hr, 1601 const VerifyOption vo) const; 1602 1603 bool is_obj_dead_cond(const oop obj, 1604 const VerifyOption vo) const; 1605 1606 // Printing 1607 1608 virtual void print_on(outputStream* st) const; 1609 virtual void print_extended_on(outputStream* st) const; 1610 virtual void print_on_error(outputStream* st) const; 1611 1612 virtual void print_gc_threads_on(outputStream* st) const; 1613 virtual void gc_threads_do(ThreadClosure* tc) const; 1614 1615 // Override 1616 void print_tracing_info() const; 1617 1618 // The following two methods are helpful for debugging RSet issues. 1619 void print_cset_rsets() PRODUCT_RETURN; 1620 void print_all_rsets() PRODUCT_RETURN; 1621 1622 public: 1623 size_t pending_card_num(); 1624 size_t cards_scanned(); 1625 1626 protected: 1627 size_t _max_heap_capacity; 1628 }; 1629 1630 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP