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 friend class HeapRegionClaimer; 216 217 // Testing classes. 218 friend class G1CheckCSetFastTableClosure; 219 220 private: 221 // The one and only G1CollectedHeap, so static functions can find it. 222 static G1CollectedHeap* _g1h; 223 224 static size_t _humongous_object_threshold_in_words; 225 226 // The secondary free list which contains regions that have been 227 // freed up during the cleanup process. This will be appended to 228 // the master free list when appropriate. 229 FreeRegionList _secondary_free_list; 230 231 // It keeps track of the old regions. 232 HeapRegionSet _old_set; 233 234 // It keeps track of the humongous regions. 235 HeapRegionSet _humongous_set; 236 237 void clear_humongous_is_live_table(); 238 void eagerly_reclaim_humongous_regions(); 239 240 // The number of regions we could create by expansion. 241 uint _expansion_regions; 242 243 // The block offset table for the G1 heap. 244 G1BlockOffsetSharedArray* _bot_shared; 245 246 // Tears down the region sets / lists so that they are empty and the 247 // regions on the heap do not belong to a region set / list. The 248 // only exception is the humongous set which we leave unaltered. If 249 // free_list_only is true, it will only tear down the master free 250 // list. It is called before a Full GC (free_list_only == false) or 251 // before heap shrinking (free_list_only == true). 252 void tear_down_region_sets(bool free_list_only); 253 254 // Rebuilds the region sets / lists so that they are repopulated to 255 // reflect the contents of the heap. The only exception is the 256 // humongous set which was not torn down in the first place. If 257 // free_list_only is true, it will only rebuild the master free 258 // list. It is called after a Full GC (free_list_only == false) or 259 // after heap shrinking (free_list_only == true). 260 void rebuild_region_sets(bool free_list_only); 261 262 // Callback for region mapping changed events. 263 G1RegionMappingChangedListener _listener; 264 265 // The sequence of all heap regions in the heap. 266 HeapRegionManager _hrm; 267 268 // Class that handles the different kinds of allocations. 269 G1Allocator* _allocator; 270 271 // Statistics for each allocation context 272 AllocationContextStats _allocation_context_stats; 273 274 // PLAB sizing policy for survivors. 275 PLABStats _survivor_plab_stats; 276 277 // PLAB sizing policy for tenured objects. 278 PLABStats _old_plab_stats; 279 280 // It specifies whether we should attempt to expand the heap after a 281 // region allocation failure. If heap expansion fails we set this to 282 // false so that we don't re-attempt the heap expansion (it's likely 283 // that subsequent expansion attempts will also fail if one fails). 284 // Currently, it is only consulted during GC and it's reset at the 285 // start of each GC. 286 bool _expand_heap_after_alloc_failure; 287 288 // It resets the mutator alloc region before new allocations can take place. 289 void init_mutator_alloc_region(); 290 291 // It releases the mutator alloc region. 292 void release_mutator_alloc_region(); 293 294 // It initializes the GC alloc regions at the start of a GC. 295 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 296 297 // It releases the GC alloc regions at the end of a GC. 298 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 299 300 // It does any cleanup that needs to be done on the GC alloc regions 301 // before a Full GC. 302 void abandon_gc_alloc_regions(); 303 304 // Helper for monitoring and management support. 305 G1MonitoringSupport* _g1mm; 306 307 // Records whether the region at the given index is kept live by roots or 308 // references from the young generation. 309 class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> { 310 protected: 311 bool default_value() const { return false; } 312 public: 313 void clear() { G1BiasedMappedArray<bool>::clear(); } 314 void set_live(uint region) { 315 set_by_index(region, true); 316 } 317 bool is_live(uint region) { 318 return get_by_index(region); 319 } 320 }; 321 322 HumongousIsLiveBiasedMappedArray _humongous_is_live; 323 // Stores whether during humongous object registration we found candidate regions. 324 // If not, we can skip a few steps. 325 bool _has_humongous_reclaim_candidates; 326 327 volatile unsigned _gc_time_stamp; 328 329 size_t* _surviving_young_words; 330 331 G1HRPrinter _hr_printer; 332 333 void setup_surviving_young_words(); 334 void update_surviving_young_words(size_t* surv_young_words); 335 void cleanup_surviving_young_words(); 336 337 // It decides whether an explicit GC should start a concurrent cycle 338 // instead of doing a STW GC. Currently, a concurrent cycle is 339 // explicitly started if: 340 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 341 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 342 // (c) cause == _g1_humongous_allocation 343 bool should_do_concurrent_full_gc(GCCause::Cause cause); 344 345 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 346 // concurrent cycles) we have started. 347 volatile unsigned int _old_marking_cycles_started; 348 349 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 350 // concurrent cycles) we have completed. 351 volatile unsigned int _old_marking_cycles_completed; 352 353 bool _concurrent_cycle_started; 354 bool _heap_summary_sent; 355 356 // This is a non-product method that is helpful for testing. It is 357 // called at the end of a GC and artificially expands the heap by 358 // allocating a number of dead regions. This way we can induce very 359 // frequent marking cycles and stress the cleanup / concurrent 360 // cleanup code more (as all the regions that will be allocated by 361 // this method will be found dead by the marking cycle). 362 void allocate_dummy_regions() PRODUCT_RETURN; 363 364 // Clear RSets after a compaction. It also resets the GC time stamps. 365 void clear_rsets_post_compaction(); 366 367 // If the HR printer is active, dump the state of the regions in the 368 // heap after a compaction. 369 void print_hrm_post_compaction(); 370 371 double verify(bool guard, const char* msg); 372 void verify_before_gc(); 373 void verify_after_gc(); 374 375 void log_gc_header(); 376 void log_gc_footer(double pause_time_sec); 377 378 // These are macros so that, if the assert fires, we get the correct 379 // line number, file, etc. 380 381 #define heap_locking_asserts_err_msg(_extra_message_) \ 382 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 383 (_extra_message_), \ 384 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 385 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 386 BOOL_TO_STR(Thread::current()->is_VM_thread())) 387 388 #define assert_heap_locked() \ 389 do { \ 390 assert(Heap_lock->owned_by_self(), \ 391 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 392 } while (0) 393 394 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 395 do { \ 396 assert(Heap_lock->owned_by_self() || \ 397 (SafepointSynchronize::is_at_safepoint() && \ 398 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 399 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 400 "should be at a safepoint")); \ 401 } while (0) 402 403 #define assert_heap_locked_and_not_at_safepoint() \ 404 do { \ 405 assert(Heap_lock->owned_by_self() && \ 406 !SafepointSynchronize::is_at_safepoint(), \ 407 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 408 "should not be at a safepoint")); \ 409 } while (0) 410 411 #define assert_heap_not_locked() \ 412 do { \ 413 assert(!Heap_lock->owned_by_self(), \ 414 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 415 } while (0) 416 417 #define assert_heap_not_locked_and_not_at_safepoint() \ 418 do { \ 419 assert(!Heap_lock->owned_by_self() && \ 420 !SafepointSynchronize::is_at_safepoint(), \ 421 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 422 "should not be at a safepoint")); \ 423 } while (0) 424 425 #define assert_at_safepoint(_should_be_vm_thread_) \ 426 do { \ 427 assert(SafepointSynchronize::is_at_safepoint() && \ 428 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 429 heap_locking_asserts_err_msg("should be at a safepoint")); \ 430 } while (0) 431 432 #define assert_not_at_safepoint() \ 433 do { \ 434 assert(!SafepointSynchronize::is_at_safepoint(), \ 435 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 436 } while (0) 437 438 protected: 439 440 // The young region list. 441 YoungList* _young_list; 442 443 // The current policy object for the collector. 444 G1CollectorPolicy* _g1_policy; 445 446 // This is the second level of trying to allocate a new region. If 447 // new_region() didn't find a region on the free_list, this call will 448 // check whether there's anything available on the 449 // secondary_free_list and/or wait for more regions to appear on 450 // that list, if _free_regions_coming is set. 451 HeapRegion* new_region_try_secondary_free_list(bool is_old); 452 453 // Try to allocate a single non-humongous HeapRegion sufficient for 454 // an allocation of the given word_size. If do_expand is true, 455 // attempt to expand the heap if necessary to satisfy the allocation 456 // request. If the region is to be used as an old region or for a 457 // humongous object, set is_old to true. If not, to false. 458 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 459 460 // Initialize a contiguous set of free regions of length num_regions 461 // and starting at index first so that they appear as a single 462 // humongous region. 463 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 464 uint num_regions, 465 size_t word_size, 466 AllocationContext_t context); 467 468 // Attempt to allocate a humongous object of the given size. Return 469 // NULL if unsuccessful. 470 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 471 472 // The following two methods, allocate_new_tlab() and 473 // mem_allocate(), are the two main entry points from the runtime 474 // into the G1's allocation routines. They have the following 475 // assumptions: 476 // 477 // * They should both be called outside safepoints. 478 // 479 // * They should both be called without holding the Heap_lock. 480 // 481 // * All allocation requests for new TLABs should go to 482 // allocate_new_tlab(). 483 // 484 // * All non-TLAB allocation requests should go to mem_allocate(). 485 // 486 // * If either call cannot satisfy the allocation request using the 487 // current allocating region, they will try to get a new one. If 488 // this fails, they will attempt to do an evacuation pause and 489 // retry the allocation. 490 // 491 // * If all allocation attempts fail, even after trying to schedule 492 // an evacuation pause, allocate_new_tlab() will return NULL, 493 // whereas mem_allocate() will attempt a heap expansion and/or 494 // schedule a Full GC. 495 // 496 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 497 // should never be called with word_size being humongous. All 498 // humongous allocation requests should go to mem_allocate() which 499 // will satisfy them with a special path. 500 501 virtual HeapWord* allocate_new_tlab(size_t word_size); 502 503 virtual HeapWord* mem_allocate(size_t word_size, 504 bool* gc_overhead_limit_was_exceeded); 505 506 // The following three methods take a gc_count_before_ret 507 // parameter which is used to return the GC count if the method 508 // returns NULL. Given that we are required to read the GC count 509 // while holding the Heap_lock, and these paths will take the 510 // Heap_lock at some point, it's easier to get them to read the GC 511 // count while holding the Heap_lock before they return NULL instead 512 // of the caller (namely: mem_allocate()) having to also take the 513 // Heap_lock just to read the GC count. 514 515 // First-level mutator allocation attempt: try to allocate out of 516 // the mutator alloc region without taking the Heap_lock. This 517 // should only be used for non-humongous allocations. 518 inline HeapWord* attempt_allocation(size_t word_size, 519 unsigned int* gc_count_before_ret, 520 int* gclocker_retry_count_ret); 521 522 // Second-level mutator allocation attempt: take the Heap_lock and 523 // retry the allocation attempt, potentially scheduling a GC 524 // pause. This should only be used for non-humongous allocations. 525 HeapWord* attempt_allocation_slow(size_t word_size, 526 AllocationContext_t context, 527 unsigned int* gc_count_before_ret, 528 int* gclocker_retry_count_ret); 529 530 // Takes the Heap_lock and attempts a humongous allocation. It can 531 // potentially schedule a GC pause. 532 HeapWord* attempt_allocation_humongous(size_t word_size, 533 unsigned int* gc_count_before_ret, 534 int* gclocker_retry_count_ret); 535 536 // Allocation attempt that should be called during safepoints (e.g., 537 // at the end of a successful GC). expect_null_mutator_alloc_region 538 // specifies whether the mutator alloc region is expected to be NULL 539 // or not. 540 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 541 AllocationContext_t context, 542 bool expect_null_mutator_alloc_region); 543 544 // It dirties the cards that cover the block so that so that the post 545 // write barrier never queues anything when updating objects on this 546 // block. It is assumed (and in fact we assert) that the block 547 // belongs to a young region. 548 inline void dirty_young_block(HeapWord* start, size_t word_size); 549 550 // Allocate blocks during garbage collection. Will ensure an 551 // allocation region, either by picking one or expanding the 552 // heap, and then allocate a block of the given size. The block 553 // may not be a humongous - it must fit into a single heap region. 554 inline HeapWord* par_allocate_during_gc(InCSetState dest, 555 size_t word_size, 556 AllocationContext_t context); 557 // Ensure that no further allocations can happen in "r", bearing in mind 558 // that parallel threads might be attempting allocations. 559 void par_allocate_remaining_space(HeapRegion* r); 560 561 // Allocation attempt during GC for a survivor object / PLAB. 562 inline HeapWord* survivor_attempt_allocation(size_t word_size, 563 AllocationContext_t context); 564 565 // Allocation attempt during GC for an old object / PLAB. 566 inline HeapWord* old_attempt_allocation(size_t word_size, 567 AllocationContext_t context); 568 569 // These methods are the "callbacks" from the G1AllocRegion class. 570 571 // For mutator alloc regions. 572 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 573 void retire_mutator_alloc_region(HeapRegion* alloc_region, 574 size_t allocated_bytes); 575 576 // For GC alloc regions. 577 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 578 InCSetState dest); 579 void retire_gc_alloc_region(HeapRegion* alloc_region, 580 size_t allocated_bytes, InCSetState dest); 581 582 // - if explicit_gc is true, the GC is for a System.gc() or a heap 583 // inspection request and should collect the entire heap 584 // - if clear_all_soft_refs is true, all soft references should be 585 // cleared during the GC 586 // - if explicit_gc is false, word_size describes the allocation that 587 // the GC should attempt (at least) to satisfy 588 // - it returns false if it is unable to do the collection due to the 589 // GC locker being active, true otherwise 590 bool do_collection(bool explicit_gc, 591 bool clear_all_soft_refs, 592 size_t word_size); 593 594 // Callback from VM_G1CollectFull operation. 595 // Perform a full collection. 596 virtual void do_full_collection(bool clear_all_soft_refs); 597 598 // Resize the heap if necessary after a full collection. If this is 599 // after a collect-for allocation, "word_size" is the allocation size, 600 // and will be considered part of the used portion of the heap. 601 void resize_if_necessary_after_full_collection(size_t word_size); 602 603 // Callback from VM_G1CollectForAllocation operation. 604 // This function does everything necessary/possible to satisfy a 605 // failed allocation request (including collection, expansion, etc.) 606 HeapWord* satisfy_failed_allocation(size_t word_size, 607 AllocationContext_t context, 608 bool* succeeded); 609 610 // Attempting to expand the heap sufficiently 611 // to support an allocation of the given "word_size". If 612 // successful, perform the allocation and return the address of the 613 // allocated block, or else "NULL". 614 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 615 616 // Process any reference objects discovered during 617 // an incremental evacuation pause. 618 void process_discovered_references(uint no_of_gc_workers); 619 620 // Enqueue any remaining discovered references 621 // after processing. 622 void enqueue_discovered_references(uint no_of_gc_workers); 623 624 public: 625 626 G1Allocator* allocator() { 627 return _allocator; 628 } 629 630 G1MonitoringSupport* g1mm() { 631 assert(_g1mm != NULL, "should have been initialized"); 632 return _g1mm; 633 } 634 635 // Expand the garbage-first heap by at least the given size (in bytes!). 636 // Returns true if the heap was expanded by the requested amount; 637 // false otherwise. 638 // (Rounds up to a HeapRegion boundary.) 639 bool expand(size_t expand_bytes); 640 641 // Returns the PLAB statistics for a given destination. 642 inline PLABStats* alloc_buffer_stats(InCSetState dest); 643 644 // Determines PLAB size for a given destination. 645 inline size_t desired_plab_sz(InCSetState dest); 646 647 inline AllocationContextStats& allocation_context_stats(); 648 649 // Do anything common to GC's. 650 virtual void gc_prologue(bool full); 651 virtual void gc_epilogue(bool full); 652 653 inline void set_humongous_is_live(oop obj); 654 655 bool humongous_is_live(uint region) { 656 return _humongous_is_live.is_live(region); 657 } 658 659 // Returns whether the given region (which must be a humongous (start) region) 660 // is to be considered conservatively live regardless of any other conditions. 661 bool humongous_region_is_always_live(uint index); 662 // Register the given region to be part of the collection set. 663 inline void register_humongous_region_with_in_cset_fast_test(uint index); 664 // Register regions with humongous objects (actually on the start region) in 665 // the in_cset_fast_test table. 666 void register_humongous_regions_with_in_cset_fast_test(); 667 // We register a region with the fast "in collection set" test. We 668 // simply set to true the array slot corresponding to this region. 669 void register_young_region_with_in_cset_fast_test(HeapRegion* r) { 670 _in_cset_fast_test.set_in_young(r->hrm_index()); 671 } 672 void register_old_region_with_in_cset_fast_test(HeapRegion* r) { 673 _in_cset_fast_test.set_in_old(r->hrm_index()); 674 } 675 676 // This is a fast test on whether a reference points into the 677 // collection set or not. Assume that the reference 678 // points into the heap. 679 inline bool in_cset_fast_test(oop obj); 680 681 void clear_cset_fast_test() { 682 _in_cset_fast_test.clear(); 683 } 684 685 // This is called at the start of either a concurrent cycle or a Full 686 // GC to update the number of old marking cycles started. 687 void increment_old_marking_cycles_started(); 688 689 // This is called at the end of either a concurrent cycle or a Full 690 // GC to update the number of old marking cycles completed. Those two 691 // can happen in a nested fashion, i.e., we start a concurrent 692 // cycle, a Full GC happens half-way through it which ends first, 693 // and then the cycle notices that a Full GC happened and ends 694 // too. The concurrent parameter is a boolean to help us do a bit 695 // tighter consistency checking in the method. If concurrent is 696 // false, the caller is the inner caller in the nesting (i.e., the 697 // Full GC). If concurrent is true, the caller is the outer caller 698 // in this nesting (i.e., the concurrent cycle). Further nesting is 699 // not currently supported. The end of this call also notifies 700 // the FullGCCount_lock in case a Java thread is waiting for a full 701 // GC to happen (e.g., it called System.gc() with 702 // +ExplicitGCInvokesConcurrent). 703 void increment_old_marking_cycles_completed(bool concurrent); 704 705 unsigned int old_marking_cycles_completed() { 706 return _old_marking_cycles_completed; 707 } 708 709 void register_concurrent_cycle_start(const Ticks& start_time); 710 void register_concurrent_cycle_end(); 711 void trace_heap_after_concurrent_cycle(); 712 713 G1YCType yc_type(); 714 715 G1HRPrinter* hr_printer() { return &_hr_printer; } 716 717 // Frees a non-humongous region by initializing its contents and 718 // adding it to the free list that's passed as a parameter (this is 719 // usually a local list which will be appended to the master free 720 // list later). The used bytes of freed regions are accumulated in 721 // pre_used. If par is true, the region's RSet will not be freed 722 // up. The assumption is that this will be done later. 723 // The locked parameter indicates if the caller has already taken 724 // care of proper synchronization. This may allow some optimizations. 725 void free_region(HeapRegion* hr, 726 FreeRegionList* free_list, 727 bool par, 728 bool locked = false); 729 730 // Frees a humongous region by collapsing it into individual regions 731 // and calling free_region() for each of them. The freed regions 732 // will be added to the free list that's passed as a parameter (this 733 // is usually a local list which will be appended to the master free 734 // list later). The used bytes of freed regions are accumulated in 735 // pre_used. If par is true, the region's RSet will not be freed 736 // up. The assumption is that this will be done later. 737 void free_humongous_region(HeapRegion* hr, 738 FreeRegionList* free_list, 739 bool par); 740 protected: 741 742 // Shrink the garbage-first heap by at most the given size (in bytes!). 743 // (Rounds down to a HeapRegion boundary.) 744 virtual void shrink(size_t expand_bytes); 745 void shrink_helper(size_t expand_bytes); 746 747 #if TASKQUEUE_STATS 748 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 749 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 750 void reset_taskqueue_stats(); 751 #endif // TASKQUEUE_STATS 752 753 // Schedule the VM operation that will do an evacuation pause to 754 // satisfy an allocation request of word_size. *succeeded will 755 // return whether the VM operation was successful (it did do an 756 // evacuation pause) or not (another thread beat us to it or the GC 757 // locker was active). Given that we should not be holding the 758 // Heap_lock when we enter this method, we will pass the 759 // gc_count_before (i.e., total_collections()) as a parameter since 760 // it has to be read while holding the Heap_lock. Currently, both 761 // methods that call do_collection_pause() release the Heap_lock 762 // before the call, so it's easy to read gc_count_before just before. 763 HeapWord* do_collection_pause(size_t word_size, 764 unsigned int gc_count_before, 765 bool* succeeded, 766 GCCause::Cause gc_cause); 767 768 // The guts of the incremental collection pause, executed by the vm 769 // thread. It returns false if it is unable to do the collection due 770 // to the GC locker being active, true otherwise 771 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 772 773 // Actually do the work of evacuating the collection set. 774 void evacuate_collection_set(EvacuationInfo& evacuation_info); 775 776 // The g1 remembered set of the heap. 777 G1RemSet* _g1_rem_set; 778 779 // A set of cards that cover the objects for which the Rsets should be updated 780 // concurrently after the collection. 781 DirtyCardQueueSet _dirty_card_queue_set; 782 783 // The closure used to refine a single card. 784 RefineCardTableEntryClosure* _refine_cte_cl; 785 786 // A DirtyCardQueueSet that is used to hold cards that contain 787 // references into the current collection set. This is used to 788 // update the remembered sets of the regions in the collection 789 // set in the event of an evacuation failure. 790 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 791 792 // After a collection pause, make the regions in the CS into free 793 // regions. 794 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 795 796 // Abandon the current collection set without recording policy 797 // statistics or updating free lists. 798 void abandon_collection_set(HeapRegion* cs_head); 799 800 // Applies "scan_non_heap_roots" to roots outside the heap, 801 // "scan_rs" to roots inside the heap (having done "set_region" to 802 // indicate the region in which the root resides), 803 // and does "scan_metadata" If "scan_rs" is 804 // NULL, then this step is skipped. The "worker_i" 805 // param is for use with parallel roots processing, and should be 806 // the "i" of the calling parallel worker thread's work(i) function. 807 // In the sequential case this param will be ignored. 808 void g1_process_roots(OopClosure* scan_non_heap_roots, 809 OopClosure* scan_non_heap_weak_roots, 810 G1ParPushHeapRSClosure* scan_rs, 811 CLDClosure* scan_strong_clds, 812 CLDClosure* scan_weak_clds, 813 CodeBlobClosure* scan_strong_code, 814 uint worker_i); 815 816 // The concurrent marker (and the thread it runs in.) 817 ConcurrentMark* _cm; 818 ConcurrentMarkThread* _cmThread; 819 bool _mark_in_progress; 820 821 // The concurrent refiner. 822 ConcurrentG1Refine* _cg1r; 823 824 // The parallel task queues 825 RefToScanQueueSet *_task_queues; 826 827 // True iff a evacuation has failed in the current collection. 828 bool _evacuation_failed; 829 830 EvacuationFailedInfo* _evacuation_failed_info_array; 831 832 // Failed evacuations cause some logical from-space objects to have 833 // forwarding pointers to themselves. Reset them. 834 void remove_self_forwarding_pointers(); 835 836 // Together, these store an object with a preserved mark, and its mark value. 837 Stack<oop, mtGC> _objs_with_preserved_marks; 838 Stack<markOop, mtGC> _preserved_marks_of_objs; 839 840 // Preserve the mark of "obj", if necessary, in preparation for its mark 841 // word being overwritten with a self-forwarding-pointer. 842 void preserve_mark_if_necessary(oop obj, markOop m); 843 844 // The stack of evac-failure objects left to be scanned. 845 GrowableArray<oop>* _evac_failure_scan_stack; 846 // The closure to apply to evac-failure objects. 847 848 OopsInHeapRegionClosure* _evac_failure_closure; 849 // Set the field above. 850 void 851 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 852 _evac_failure_closure = evac_failure_closure; 853 } 854 855 // Push "obj" on the scan stack. 856 void push_on_evac_failure_scan_stack(oop obj); 857 // Process scan stack entries until the stack is empty. 858 void drain_evac_failure_scan_stack(); 859 // True iff an invocation of "drain_scan_stack" is in progress; to 860 // prevent unnecessary recursion. 861 bool _drain_in_progress; 862 863 // Do any necessary initialization for evacuation-failure handling. 864 // "cl" is the closure that will be used to process evac-failure 865 // objects. 866 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 867 // Do any necessary cleanup for evacuation-failure handling data 868 // structures. 869 void finalize_for_evac_failure(); 870 871 // An attempt to evacuate "obj" has failed; take necessary steps. 872 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 873 void handle_evacuation_failure_common(oop obj, markOop m); 874 875 #ifndef PRODUCT 876 // Support for forcing evacuation failures. Analogous to 877 // PromotionFailureALot for the other collectors. 878 879 // Records whether G1EvacuationFailureALot should be in effect 880 // for the current GC 881 bool _evacuation_failure_alot_for_current_gc; 882 883 // Used to record the GC number for interval checking when 884 // determining whether G1EvaucationFailureALot is in effect 885 // for the current GC. 886 size_t _evacuation_failure_alot_gc_number; 887 888 // Count of the number of evacuations between failures. 889 volatile size_t _evacuation_failure_alot_count; 890 891 // Set whether G1EvacuationFailureALot should be in effect 892 // for the current GC (based upon the type of GC and which 893 // command line flags are set); 894 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 895 bool during_initial_mark, 896 bool during_marking); 897 898 inline void set_evacuation_failure_alot_for_current_gc(); 899 900 // Return true if it's time to cause an evacuation failure. 901 inline bool evacuation_should_fail(); 902 903 // Reset the G1EvacuationFailureALot counters. Should be called at 904 // the end of an evacuation pause in which an evacuation failure occurred. 905 inline void reset_evacuation_should_fail(); 906 #endif // !PRODUCT 907 908 // ("Weak") Reference processing support. 909 // 910 // G1 has 2 instances of the reference processor class. One 911 // (_ref_processor_cm) handles reference object discovery 912 // and subsequent processing during concurrent marking cycles. 913 // 914 // The other (_ref_processor_stw) handles reference object 915 // discovery and processing during full GCs and incremental 916 // evacuation pauses. 917 // 918 // During an incremental pause, reference discovery will be 919 // temporarily disabled for _ref_processor_cm and will be 920 // enabled for _ref_processor_stw. At the end of the evacuation 921 // pause references discovered by _ref_processor_stw will be 922 // processed and discovery will be disabled. The previous 923 // setting for reference object discovery for _ref_processor_cm 924 // will be re-instated. 925 // 926 // At the start of marking: 927 // * Discovery by the CM ref processor is verified to be inactive 928 // and it's discovered lists are empty. 929 // * Discovery by the CM ref processor is then enabled. 930 // 931 // At the end of marking: 932 // * Any references on the CM ref processor's discovered 933 // lists are processed (possibly MT). 934 // 935 // At the start of full GC we: 936 // * Disable discovery by the CM ref processor and 937 // empty CM ref processor's discovered lists 938 // (without processing any entries). 939 // * Verify that the STW ref processor is inactive and it's 940 // discovered lists are empty. 941 // * Temporarily set STW ref processor discovery as single threaded. 942 // * Temporarily clear the STW ref processor's _is_alive_non_header 943 // field. 944 // * Finally enable discovery by the STW ref processor. 945 // 946 // The STW ref processor is used to record any discovered 947 // references during the full GC. 948 // 949 // At the end of a full GC we: 950 // * Enqueue any reference objects discovered by the STW ref processor 951 // that have non-live referents. This has the side-effect of 952 // making the STW ref processor inactive by disabling discovery. 953 // * Verify that the CM ref processor is still inactive 954 // and no references have been placed on it's discovered 955 // lists (also checked as a precondition during initial marking). 956 957 // The (stw) reference processor... 958 ReferenceProcessor* _ref_processor_stw; 959 960 STWGCTimer* _gc_timer_stw; 961 ConcurrentGCTimer* _gc_timer_cm; 962 963 G1OldTracer* _gc_tracer_cm; 964 G1NewTracer* _gc_tracer_stw; 965 966 // During reference object discovery, the _is_alive_non_header 967 // closure (if non-null) is applied to the referent object to 968 // determine whether the referent is live. If so then the 969 // reference object does not need to be 'discovered' and can 970 // be treated as a regular oop. This has the benefit of reducing 971 // the number of 'discovered' reference objects that need to 972 // be processed. 973 // 974 // Instance of the is_alive closure for embedding into the 975 // STW reference processor as the _is_alive_non_header field. 976 // Supplying a value for the _is_alive_non_header field is 977 // optional but doing so prevents unnecessary additions to 978 // the discovered lists during reference discovery. 979 G1STWIsAliveClosure _is_alive_closure_stw; 980 981 // The (concurrent marking) reference processor... 982 ReferenceProcessor* _ref_processor_cm; 983 984 // Instance of the concurrent mark is_alive closure for embedding 985 // into the Concurrent Marking reference processor as the 986 // _is_alive_non_header field. Supplying a value for the 987 // _is_alive_non_header field is optional but doing so prevents 988 // unnecessary additions to the discovered lists during reference 989 // discovery. 990 G1CMIsAliveClosure _is_alive_closure_cm; 991 992 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 993 HeapRegion** _worker_cset_start_region; 994 995 // Time stamp to validate the regions recorded in the cache 996 // used by G1CollectedHeap::start_cset_region_for_worker(). 997 // The heap region entry for a given worker is valid iff 998 // the associated time stamp value matches the current value 999 // of G1CollectedHeap::_gc_time_stamp. 1000 unsigned int* _worker_cset_start_region_time_stamp; 1001 1002 enum G1H_process_roots_tasks { 1003 G1H_PS_filter_satb_buffers, 1004 G1H_PS_refProcessor_oops_do, 1005 // Leave this one last. 1006 G1H_PS_NumElements 1007 }; 1008 1009 SubTasksDone* _process_strong_tasks; 1010 1011 volatile bool _free_regions_coming; 1012 1013 public: 1014 1015 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1016 1017 void set_refine_cte_cl_concurrency(bool concurrent); 1018 1019 RefToScanQueue *task_queue(int i) const; 1020 1021 // A set of cards where updates happened during the GC 1022 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1023 1024 // A DirtyCardQueueSet that is used to hold cards that contain 1025 // references into the current collection set. This is used to 1026 // update the remembered sets of the regions in the collection 1027 // set in the event of an evacuation failure. 1028 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1029 { return _into_cset_dirty_card_queue_set; } 1030 1031 // Create a G1CollectedHeap with the specified policy. 1032 // Must call the initialize method afterwards. 1033 // May not return if something goes wrong. 1034 G1CollectedHeap(G1CollectorPolicy* policy); 1035 1036 // Initialize the G1CollectedHeap to have the initial and 1037 // maximum sizes and remembered and barrier sets 1038 // specified by the policy object. 1039 jint initialize(); 1040 1041 virtual void stop(); 1042 1043 // Return the (conservative) maximum heap alignment for any G1 heap 1044 static size_t conservative_max_heap_alignment(); 1045 1046 // Initialize weak reference processing. 1047 virtual void ref_processing_init(); 1048 1049 void set_par_threads(uint t) { 1050 SharedHeap::set_par_threads(t); 1051 // Done in SharedHeap but oddly there are 1052 // two _process_strong_tasks's in a G1CollectedHeap 1053 // so do it here too. 1054 _process_strong_tasks->set_n_threads(t); 1055 } 1056 1057 // Set _n_par_threads according to a policy TBD. 1058 void set_par_threads(); 1059 1060 void set_n_termination(int t) { 1061 _process_strong_tasks->set_n_threads(t); 1062 } 1063 1064 virtual CollectedHeap::Name kind() const { 1065 return CollectedHeap::G1CollectedHeap; 1066 } 1067 1068 // The current policy object for the collector. 1069 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1070 1071 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1072 1073 // Adaptive size policy. No such thing for g1. 1074 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1075 1076 // The rem set and barrier set. 1077 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1078 1079 unsigned get_gc_time_stamp() { 1080 return _gc_time_stamp; 1081 } 1082 1083 inline void reset_gc_time_stamp(); 1084 1085 void check_gc_time_stamps() PRODUCT_RETURN; 1086 1087 inline void increment_gc_time_stamp(); 1088 1089 // Reset the given region's GC timestamp. If it's starts humongous, 1090 // also reset the GC timestamp of its corresponding 1091 // continues humongous regions too. 1092 void reset_gc_time_stamps(HeapRegion* hr); 1093 1094 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1095 DirtyCardQueue* into_cset_dcq, 1096 bool concurrent, uint worker_i); 1097 1098 // The shared block offset table array. 1099 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1100 1101 // Reference Processing accessors 1102 1103 // The STW reference processor.... 1104 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1105 1106 // The Concurrent Marking reference processor... 1107 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1108 1109 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1110 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1111 1112 virtual size_t capacity() const; 1113 virtual size_t used() const; 1114 // This should be called when we're not holding the heap lock. The 1115 // result might be a bit inaccurate. 1116 size_t used_unlocked() const; 1117 size_t recalculate_used() const; 1118 1119 // These virtual functions do the actual allocation. 1120 // Some heaps may offer a contiguous region for shared non-blocking 1121 // allocation, via inlined code (by exporting the address of the top and 1122 // end fields defining the extent of the contiguous allocation region.) 1123 // But G1CollectedHeap doesn't yet support this. 1124 1125 virtual bool is_maximal_no_gc() const { 1126 return _hrm.available() == 0; 1127 } 1128 1129 // The current number of regions in the heap. 1130 uint num_regions() const { return _hrm.length(); } 1131 1132 // The max number of regions in the heap. 1133 uint max_regions() const { return _hrm.max_length(); } 1134 1135 // The number of regions that are completely free. 1136 uint num_free_regions() const { return _hrm.num_free_regions(); } 1137 1138 // The number of regions that are not completely free. 1139 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1140 1141 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1142 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1143 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1144 void verify_dirty_young_regions() PRODUCT_RETURN; 1145 1146 #ifndef PRODUCT 1147 // Make sure that the given bitmap has no marked objects in the 1148 // range [from,limit). If it does, print an error message and return 1149 // false. Otherwise, just return true. bitmap_name should be "prev" 1150 // or "next". 1151 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1152 HeapWord* from, HeapWord* limit); 1153 1154 // Verify that the prev / next bitmap range [tams,end) for the given 1155 // region has no marks. Return true if all is well, false if errors 1156 // are detected. 1157 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1158 #endif // PRODUCT 1159 1160 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1161 // the given region do not have any spurious marks. If errors are 1162 // detected, print appropriate error messages and crash. 1163 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1164 1165 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1166 // have any spurious marks. If errors are detected, print 1167 // appropriate error messages and crash. 1168 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1169 1170 // Do sanity check on the contents of the in-cset fast test table. 1171 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1172 1173 // verify_region_sets() performs verification over the region 1174 // lists. It will be compiled in the product code to be used when 1175 // necessary (i.e., during heap verification). 1176 void verify_region_sets(); 1177 1178 // verify_region_sets_optional() is planted in the code for 1179 // list verification in non-product builds (and it can be enabled in 1180 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1181 #if HEAP_REGION_SET_FORCE_VERIFY 1182 void verify_region_sets_optional() { 1183 verify_region_sets(); 1184 } 1185 #else // HEAP_REGION_SET_FORCE_VERIFY 1186 void verify_region_sets_optional() { } 1187 #endif // HEAP_REGION_SET_FORCE_VERIFY 1188 1189 #ifdef ASSERT 1190 bool is_on_master_free_list(HeapRegion* hr) { 1191 return _hrm.is_free(hr); 1192 } 1193 #endif // ASSERT 1194 1195 // Wrapper for the region list operations that can be called from 1196 // methods outside this class. 1197 1198 void secondary_free_list_add(FreeRegionList* list) { 1199 _secondary_free_list.add_ordered(list); 1200 } 1201 1202 void append_secondary_free_list() { 1203 _hrm.insert_list_into_free_list(&_secondary_free_list); 1204 } 1205 1206 void append_secondary_free_list_if_not_empty_with_lock() { 1207 // If the secondary free list looks empty there's no reason to 1208 // take the lock and then try to append it. 1209 if (!_secondary_free_list.is_empty()) { 1210 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1211 append_secondary_free_list(); 1212 } 1213 } 1214 1215 inline void old_set_remove(HeapRegion* hr); 1216 1217 size_t non_young_capacity_bytes() { 1218 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1219 } 1220 1221 void set_free_regions_coming(); 1222 void reset_free_regions_coming(); 1223 bool free_regions_coming() { return _free_regions_coming; } 1224 void wait_while_free_regions_coming(); 1225 1226 // Determine whether the given region is one that we are using as an 1227 // old GC alloc region. 1228 bool is_old_gc_alloc_region(HeapRegion* hr) { 1229 return _allocator->is_retained_old_region(hr); 1230 } 1231 1232 // Perform a collection of the heap; intended for use in implementing 1233 // "System.gc". This probably implies as full a collection as the 1234 // "CollectedHeap" supports. 1235 virtual void collect(GCCause::Cause cause); 1236 1237 // The same as above but assume that the caller holds the Heap_lock. 1238 void collect_locked(GCCause::Cause cause); 1239 1240 virtual bool copy_allocation_context_stats(const jint* contexts, 1241 jlong* totals, 1242 jbyte* accuracy, 1243 jint len); 1244 1245 // True iff an evacuation has failed in the most-recent collection. 1246 bool evacuation_failed() { return _evacuation_failed; } 1247 1248 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1249 void prepend_to_freelist(FreeRegionList* list); 1250 void decrement_summary_bytes(size_t bytes); 1251 1252 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1253 virtual bool is_in(const void* p) const; 1254 #ifdef ASSERT 1255 // Returns whether p is in one of the available areas of the heap. Slow but 1256 // extensive version. 1257 bool is_in_exact(const void* p) const; 1258 #endif 1259 1260 // Return "TRUE" iff the given object address is within the collection 1261 // set. Slow implementation. 1262 inline bool obj_in_cs(oop obj); 1263 1264 inline bool is_in_cset(oop obj); 1265 1266 inline bool is_in_cset_or_humongous(const oop obj); 1267 1268 private: 1269 // This array is used for a quick test on whether a reference points into 1270 // the collection set or not. Each of the array's elements denotes whether the 1271 // corresponding region is in the collection set or not. 1272 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1273 1274 public: 1275 1276 inline InCSetState in_cset_state(const oop obj); 1277 1278 // Return "TRUE" iff the given object address is in the reserved 1279 // region of g1. 1280 bool is_in_g1_reserved(const void* p) const { 1281 return _hrm.reserved().contains(p); 1282 } 1283 1284 // Returns a MemRegion that corresponds to the space that has been 1285 // reserved for the heap 1286 MemRegion g1_reserved() const { 1287 return _hrm.reserved(); 1288 } 1289 1290 virtual bool is_in_closed_subset(const void* p) const; 1291 1292 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1293 return (G1SATBCardTableLoggingModRefBS*) barrier_set(); 1294 } 1295 1296 // This resets the card table to all zeros. It is used after 1297 // a collection pause which used the card table to claim cards. 1298 void cleanUpCardTable(); 1299 1300 // Iteration functions. 1301 1302 // Iterate over all the ref-containing fields of all objects, calling 1303 // "cl.do_oop" on each. 1304 virtual void oop_iterate(ExtendedOopClosure* cl); 1305 1306 // Iterate over all objects, calling "cl.do_object" on each. 1307 virtual void object_iterate(ObjectClosure* cl); 1308 1309 virtual void safe_object_iterate(ObjectClosure* cl) { 1310 object_iterate(cl); 1311 } 1312 1313 // Iterate over all spaces in use in the heap, in ascending address order. 1314 virtual void space_iterate(SpaceClosure* cl); 1315 1316 // Iterate over heap regions, in address order, terminating the 1317 // iteration early if the "doHeapRegion" method returns "true". 1318 void heap_region_iterate(HeapRegionClosure* blk) const; 1319 1320 // Return the region with the given index. It assumes the index is valid. 1321 inline HeapRegion* region_at(uint index) const; 1322 1323 // Calculate the region index of the given address. Given address must be 1324 // within the heap. 1325 inline uint addr_to_region(HeapWord* addr) const; 1326 1327 inline HeapWord* bottom_addr_for_region(uint index) const; 1328 1329 // Iterate over the heap regions in parallel. Assumes that this will be called 1330 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1331 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1332 // to each of the regions, by attempting to claim the region using the 1333 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1334 // region. The concurrent argument should be set to true if iteration is 1335 // performed concurrently, during which no assumptions are made for consistent 1336 // attributes of the heap regions (as they might be modified while iterating). 1337 void heap_region_par_iterate(HeapRegionClosure* cl, 1338 uint worker_id, 1339 HeapRegionClaimer* hrclaimer, 1340 bool concurrent = false) const; 1341 1342 // Clear the cached cset start regions and (more importantly) 1343 // the time stamps. Called when we reset the GC time stamp. 1344 void clear_cset_start_regions(); 1345 1346 // Given the id of a worker, obtain or calculate a suitable 1347 // starting region for iterating over the current collection set. 1348 HeapRegion* start_cset_region_for_worker(uint worker_i); 1349 1350 // Iterate over the regions (if any) in the current collection set. 1351 void collection_set_iterate(HeapRegionClosure* blk); 1352 1353 // As above but starting from region r 1354 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1355 1356 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1357 1358 // A CollectedHeap will contain some number of spaces. This finds the 1359 // space containing a given address, or else returns NULL. 1360 virtual Space* space_containing(const void* addr) const; 1361 1362 // Returns the HeapRegion that contains addr. addr must not be NULL. 1363 template <class T> 1364 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1365 1366 // Returns the HeapRegion that contains addr. addr must not be NULL. 1367 // If addr is within a humongous continues region, it returns its humongous start region. 1368 template <class T> 1369 inline HeapRegion* heap_region_containing(const T addr) const; 1370 1371 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1372 // each address in the (reserved) heap is a member of exactly 1373 // one block. The defining characteristic of a block is that it is 1374 // possible to find its size, and thus to progress forward to the next 1375 // block. (Blocks may be of different sizes.) Thus, blocks may 1376 // represent Java objects, or they might be free blocks in a 1377 // free-list-based heap (or subheap), as long as the two kinds are 1378 // distinguishable and the size of each is determinable. 1379 1380 // Returns the address of the start of the "block" that contains the 1381 // address "addr". We say "blocks" instead of "object" since some heaps 1382 // may not pack objects densely; a chunk may either be an object or a 1383 // non-object. 1384 virtual HeapWord* block_start(const void* addr) const; 1385 1386 // Requires "addr" to be the start of a chunk, and returns its size. 1387 // "addr + size" is required to be the start of a new chunk, or the end 1388 // of the active area of the heap. 1389 virtual size_t block_size(const HeapWord* addr) const; 1390 1391 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1392 // the block is an object. 1393 virtual bool block_is_obj(const HeapWord* addr) const; 1394 1395 // Does this heap support heap inspection? (+PrintClassHistogram) 1396 virtual bool supports_heap_inspection() const { return true; } 1397 1398 // Section on thread-local allocation buffers (TLABs) 1399 // See CollectedHeap for semantics. 1400 1401 bool supports_tlab_allocation() const; 1402 size_t tlab_capacity(Thread* ignored) const; 1403 size_t tlab_used(Thread* ignored) const; 1404 size_t max_tlab_size() const; 1405 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1406 1407 // Can a compiler initialize a new object without store barriers? 1408 // This permission only extends from the creation of a new object 1409 // via a TLAB up to the first subsequent safepoint. If such permission 1410 // is granted for this heap type, the compiler promises to call 1411 // defer_store_barrier() below on any slow path allocation of 1412 // a new object for which such initializing store barriers will 1413 // have been elided. G1, like CMS, allows this, but should be 1414 // ready to provide a compensating write barrier as necessary 1415 // if that storage came out of a non-young region. The efficiency 1416 // of this implementation depends crucially on being able to 1417 // answer very efficiently in constant time whether a piece of 1418 // storage in the heap comes from a young region or not. 1419 // See ReduceInitialCardMarks. 1420 virtual bool can_elide_tlab_store_barriers() const { 1421 return true; 1422 } 1423 1424 virtual bool card_mark_must_follow_store() const { 1425 return true; 1426 } 1427 1428 inline bool is_in_young(const oop obj); 1429 1430 #ifdef ASSERT 1431 virtual bool is_in_partial_collection(const void* p); 1432 #endif 1433 1434 virtual bool is_scavengable(const void* addr); 1435 1436 // We don't need barriers for initializing stores to objects 1437 // in the young gen: for the SATB pre-barrier, there is no 1438 // pre-value that needs to be remembered; for the remembered-set 1439 // update logging post-barrier, we don't maintain remembered set 1440 // information for young gen objects. 1441 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1442 1443 // Returns "true" iff the given word_size is "very large". 1444 static bool is_humongous(size_t word_size) { 1445 // Note this has to be strictly greater-than as the TLABs 1446 // are capped at the humongous threshold and we want to 1447 // ensure that we don't try to allocate a TLAB as 1448 // humongous and that we don't allocate a humongous 1449 // object in a TLAB. 1450 return word_size > _humongous_object_threshold_in_words; 1451 } 1452 1453 // Update mod union table with the set of dirty cards. 1454 void updateModUnion(); 1455 1456 // Set the mod union bits corresponding to the given memRegion. Note 1457 // that this is always a safe operation, since it doesn't clear any 1458 // bits. 1459 void markModUnionRange(MemRegion mr); 1460 1461 // Records the fact that a marking phase is no longer in progress. 1462 void set_marking_complete() { 1463 _mark_in_progress = false; 1464 } 1465 void set_marking_started() { 1466 _mark_in_progress = true; 1467 } 1468 bool mark_in_progress() { 1469 return _mark_in_progress; 1470 } 1471 1472 // Print the maximum heap capacity. 1473 virtual size_t max_capacity() const; 1474 1475 virtual jlong millis_since_last_gc(); 1476 1477 1478 // Convenience function to be used in situations where the heap type can be 1479 // asserted to be this type. 1480 static G1CollectedHeap* heap(); 1481 1482 void set_region_short_lived_locked(HeapRegion* hr); 1483 // add appropriate methods for any other surv rate groups 1484 1485 YoungList* young_list() const { return _young_list; } 1486 1487 // debugging 1488 bool check_young_list_well_formed() { 1489 return _young_list->check_list_well_formed(); 1490 } 1491 1492 bool check_young_list_empty(bool check_heap, 1493 bool check_sample = true); 1494 1495 // *** Stuff related to concurrent marking. It's not clear to me that so 1496 // many of these need to be public. 1497 1498 // The functions below are helper functions that a subclass of 1499 // "CollectedHeap" can use in the implementation of its virtual 1500 // functions. 1501 // This performs a concurrent marking of the live objects in a 1502 // bitmap off to the side. 1503 void doConcurrentMark(); 1504 1505 bool isMarkedPrev(oop obj) const; 1506 bool isMarkedNext(oop obj) const; 1507 1508 // Determine if an object is dead, given the object and also 1509 // the region to which the object belongs. An object is dead 1510 // iff a) it was not allocated since the last mark and b) it 1511 // is not marked. 1512 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1513 return 1514 !hr->obj_allocated_since_prev_marking(obj) && 1515 !isMarkedPrev(obj); 1516 } 1517 1518 // This function returns true when an object has been 1519 // around since the previous marking and hasn't yet 1520 // been marked during this marking. 1521 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1522 return 1523 !hr->obj_allocated_since_next_marking(obj) && 1524 !isMarkedNext(obj); 1525 } 1526 1527 // Determine if an object is dead, given only the object itself. 1528 // This will find the region to which the object belongs and 1529 // then call the region version of the same function. 1530 1531 // Added if it is NULL it isn't dead. 1532 1533 inline bool is_obj_dead(const oop obj) const; 1534 1535 inline bool is_obj_ill(const oop obj) const; 1536 1537 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1538 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1539 bool is_marked(oop obj, VerifyOption vo); 1540 const char* top_at_mark_start_str(VerifyOption vo); 1541 1542 ConcurrentMark* concurrent_mark() const { return _cm; } 1543 1544 // Refinement 1545 1546 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1547 1548 // The dirty cards region list is used to record a subset of regions 1549 // whose cards need clearing. The list if populated during the 1550 // remembered set scanning and drained during the card table 1551 // cleanup. Although the methods are reentrant, population/draining 1552 // phases must not overlap. For synchronization purposes the last 1553 // element on the list points to itself. 1554 HeapRegion* _dirty_cards_region_list; 1555 void push_dirty_cards_region(HeapRegion* hr); 1556 HeapRegion* pop_dirty_cards_region(); 1557 1558 // Optimized nmethod scanning support routines 1559 1560 // Register the given nmethod with the G1 heap. 1561 virtual void register_nmethod(nmethod* nm); 1562 1563 // Unregister the given nmethod from the G1 heap. 1564 virtual void unregister_nmethod(nmethod* nm); 1565 1566 // Free up superfluous code root memory. 1567 void purge_code_root_memory(); 1568 1569 // Rebuild the strong code root lists for each region 1570 // after a full GC. 1571 void rebuild_strong_code_roots(); 1572 1573 // Delete entries for dead interned string and clean up unreferenced symbols 1574 // in symbol table, possibly in parallel. 1575 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1576 1577 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1578 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1579 1580 // Redirty logged cards in the refinement queue. 1581 void redirty_logged_cards(); 1582 // Verification 1583 1584 // The following is just to alert the verification code 1585 // that a full collection has occurred and that the 1586 // remembered sets are no longer up to date. 1587 bool _full_collection; 1588 void set_full_collection() { _full_collection = true;} 1589 void clear_full_collection() {_full_collection = false;} 1590 bool full_collection() {return _full_collection;} 1591 1592 // Perform any cleanup actions necessary before allowing a verification. 1593 virtual void prepare_for_verify(); 1594 1595 // Perform verification. 1596 1597 // vo == UsePrevMarking -> use "prev" marking information, 1598 // vo == UseNextMarking -> use "next" marking information 1599 // vo == UseMarkWord -> use the mark word in the object header 1600 // 1601 // NOTE: Only the "prev" marking information is guaranteed to be 1602 // consistent most of the time, so most calls to this should use 1603 // vo == UsePrevMarking. 1604 // Currently, there is only one case where this is called with 1605 // vo == UseNextMarking, which is to verify the "next" marking 1606 // information at the end of remark. 1607 // Currently there is only one place where this is called with 1608 // vo == UseMarkWord, which is to verify the marking during a 1609 // full GC. 1610 void verify(bool silent, VerifyOption vo); 1611 1612 // Override; it uses the "prev" marking information 1613 virtual void verify(bool silent); 1614 1615 // The methods below are here for convenience and dispatch the 1616 // appropriate method depending on value of the given VerifyOption 1617 // parameter. The values for that parameter, and their meanings, 1618 // are the same as those above. 1619 1620 bool is_obj_dead_cond(const oop obj, 1621 const HeapRegion* hr, 1622 const VerifyOption vo) const; 1623 1624 bool is_obj_dead_cond(const oop obj, 1625 const VerifyOption vo) const; 1626 1627 // Printing 1628 1629 virtual void print_on(outputStream* st) const; 1630 virtual void print_extended_on(outputStream* st) const; 1631 virtual void print_on_error(outputStream* st) const; 1632 1633 virtual void print_gc_threads_on(outputStream* st) const; 1634 virtual void gc_threads_do(ThreadClosure* tc) const; 1635 1636 // Override 1637 void print_tracing_info() const; 1638 1639 // The following two methods are helpful for debugging RSet issues. 1640 void print_cset_rsets() PRODUCT_RETURN; 1641 void print_all_rsets() PRODUCT_RETURN; 1642 1643 public: 1644 size_t pending_card_num(); 1645 size_t cards_scanned(); 1646 1647 protected: 1648 size_t _max_heap_capacity; 1649 }; 1650 1651 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP