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