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/g1MonitoringSupport.hpp" 36 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp" 37 #include "gc_implementation/g1/g1YCTypes.hpp" 38 #include "gc_implementation/g1/heapRegionManager.hpp" 39 #include "gc_implementation/g1/heapRegionSet.hpp" 40 #include "gc_implementation/shared/hSpaceCounters.hpp" 41 #include "gc_implementation/shared/parGCAllocBuffer.hpp" 42 #include "memory/barrierSet.hpp" 43 #include "memory/memRegion.hpp" 44 #include "memory/sharedHeap.hpp" 45 #include "utilities/stack.hpp" 46 47 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 48 // It uses the "Garbage First" heap organization and algorithm, which 49 // may combine concurrent marking with parallel, incremental compaction of 50 // heap subsets that will yield large amounts of garbage. 51 52 // Forward declarations 53 class HeapRegion; 54 class HRRSCleanupTask; 55 class GenerationSpec; 56 class OopsInHeapRegionClosure; 57 class G1KlassScanClosure; 58 class G1ScanHeapEvacClosure; 59 class ObjectClosure; 60 class SpaceClosure; 61 class CompactibleSpaceClosure; 62 class Space; 63 class G1CollectorPolicy; 64 class GenRemSet; 65 class G1RemSet; 66 class HeapRegionRemSetIterator; 67 class ConcurrentMark; 68 class ConcurrentMarkThread; 69 class ConcurrentG1Refine; 70 class ConcurrentGCTimer; 71 class GenerationCounters; 72 class STWGCTimer; 73 class G1NewTracer; 74 class G1OldTracer; 75 class EvacuationFailedInfo; 76 class nmethod; 77 class Ticks; 78 79 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 80 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 81 82 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 83 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 84 85 class YoungList : public CHeapObj<mtGC> { 86 private: 87 G1CollectedHeap* _g1h; 88 89 HeapRegion* _head; 90 91 HeapRegion* _survivor_head; 92 HeapRegion* _survivor_tail; 93 94 HeapRegion* _curr; 95 96 uint _length; 97 uint _survivor_length; 98 99 size_t _last_sampled_rs_lengths; 100 size_t _sampled_rs_lengths; 101 102 void empty_list(HeapRegion* list); 103 104 public: 105 YoungList(G1CollectedHeap* g1h); 106 107 void push_region(HeapRegion* hr); 108 void add_survivor_region(HeapRegion* hr); 109 110 void empty_list(); 111 bool is_empty() { return _length == 0; } 112 uint length() { return _length; } 113 uint survivor_length() { return _survivor_length; } 114 115 // Currently we do not keep track of the used byte sum for the 116 // young list and the survivors and it'd be quite a lot of work to 117 // do so. When we'll eventually replace the young list with 118 // instances of HeapRegionLinkedList we'll get that for free. So, 119 // we'll report the more accurate information then. 120 size_t eden_used_bytes() { 121 assert(length() >= survivor_length(), "invariant"); 122 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 123 } 124 size_t survivor_used_bytes() { 125 return (size_t) survivor_length() * HeapRegion::GrainBytes; 126 } 127 128 void rs_length_sampling_init(); 129 bool rs_length_sampling_more(); 130 void rs_length_sampling_next(); 131 132 void reset_sampled_info() { 133 _last_sampled_rs_lengths = 0; 134 } 135 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 136 137 // for development purposes 138 void reset_auxilary_lists(); 139 void clear() { _head = NULL; _length = 0; } 140 141 void clear_survivors() { 142 _survivor_head = NULL; 143 _survivor_tail = NULL; 144 _survivor_length = 0; 145 } 146 147 HeapRegion* first_region() { return _head; } 148 HeapRegion* first_survivor_region() { return _survivor_head; } 149 HeapRegion* last_survivor_region() { return _survivor_tail; } 150 151 // debugging 152 bool check_list_well_formed(); 153 bool check_list_empty(bool check_sample = true); 154 void print(); 155 }; 156 157 // The G1 STW is alive closure. 158 // An instance is embedded into the G1CH and used as the 159 // (optional) _is_alive_non_header closure in the STW 160 // reference processor. It is also extensively used during 161 // reference processing during STW evacuation pauses. 162 class G1STWIsAliveClosure: public BoolObjectClosure { 163 G1CollectedHeap* _g1; 164 public: 165 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 166 bool do_object_b(oop p); 167 }; 168 169 class RefineCardTableEntryClosure; 170 171 class G1RegionMappingChangedListener : public G1MappingChangedListener { 172 private: 173 void reset_from_card_cache(uint start_idx, size_t num_regions); 174 public: 175 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 176 }; 177 178 class G1CollectedHeap : public SharedHeap { 179 friend class VM_CollectForMetadataAllocation; 180 friend class VM_G1CollectForAllocation; 181 friend class VM_G1CollectFull; 182 friend class VM_G1IncCollectionPause; 183 friend class VMStructs; 184 friend class MutatorAllocRegion; 185 friend class SurvivorGCAllocRegion; 186 friend class OldGCAllocRegion; 187 friend class G1Allocator; 188 friend class G1DefaultAllocator; 189 friend class G1ResManAllocator; 190 191 // Closures used in implementation. 192 template <G1Barrier barrier, G1Mark do_mark_object> 193 friend class G1ParCopyClosure; 194 friend class G1IsAliveClosure; 195 friend class G1EvacuateFollowersClosure; 196 friend class G1ParScanThreadState; 197 friend class G1ParScanClosureSuper; 198 friend class G1ParEvacuateFollowersClosure; 199 friend class G1ParTask; 200 friend class G1ParGCAllocator; 201 friend class G1DefaultParGCAllocator; 202 friend class G1FreeGarbageRegionClosure; 203 friend class RefineCardTableEntryClosure; 204 friend class G1PrepareCompactClosure; 205 friend class RegionSorter; 206 friend class RegionResetter; 207 friend class CountRCClosure; 208 friend class EvacPopObjClosure; 209 friend class G1ParCleanupCTTask; 210 211 friend class G1FreeHumongousRegionClosure; 212 // Other related classes. 213 friend class G1MarkSweep; 214 friend class HeapRegionClaimer; 215 216 private: 217 // The one and only G1CollectedHeap, so static functions can find it. 218 static G1CollectedHeap* _g1h; 219 220 static size_t _humongous_object_threshold_in_words; 221 222 // The secondary free list which contains regions that have been 223 // freed up during the cleanup process. This will be appended to 224 // the master free list when appropriate. 225 FreeRegionList _secondary_free_list; 226 227 // It keeps track of the old regions. 228 HeapRegionSet _old_set; 229 230 // It keeps track of the humongous regions. 231 HeapRegionSet _humongous_set; 232 233 void clear_humongous_is_live_table(); 234 void eagerly_reclaim_humongous_regions(); 235 236 // The number of regions we could create by expansion. 237 uint _expansion_regions; 238 239 // The block offset table for the G1 heap. 240 G1BlockOffsetSharedArray* _bot_shared; 241 242 // Tears down the region sets / lists so that they are empty and the 243 // regions on the heap do not belong to a region set / list. The 244 // only exception is the humongous set which we leave unaltered. If 245 // free_list_only is true, it will only tear down the master free 246 // list. It is called before a Full GC (free_list_only == false) or 247 // before heap shrinking (free_list_only == true). 248 void tear_down_region_sets(bool free_list_only); 249 250 // Rebuilds the region sets / lists so that they are repopulated to 251 // reflect the contents of the heap. The only exception is the 252 // humongous set which was not torn down in the first place. If 253 // free_list_only is true, it will only rebuild the master free 254 // list. It is called after a Full GC (free_list_only == false) or 255 // after heap shrinking (free_list_only == true). 256 void rebuild_region_sets(bool free_list_only); 257 258 // Callback for region mapping changed events. 259 G1RegionMappingChangedListener _listener; 260 261 // The sequence of all heap regions in the heap. 262 HeapRegionManager _hrm; 263 264 // Class that handles the different kinds of allocations. 265 G1Allocator* _allocator; 266 267 // Statistics for each allocation context 268 AllocationContextStats _allocation_context_stats; 269 270 // PLAB sizing policy for survivors. 271 PLABStats _survivor_plab_stats; 272 273 // PLAB sizing policy for tenured objects. 274 PLABStats _old_plab_stats; 275 276 // It specifies whether we should attempt to expand the heap after a 277 // region allocation failure. If heap expansion fails we set this to 278 // false so that we don't re-attempt the heap expansion (it's likely 279 // that subsequent expansion attempts will also fail if one fails). 280 // Currently, it is only consulted during GC and it's reset at the 281 // start of each GC. 282 bool _expand_heap_after_alloc_failure; 283 284 // It resets the mutator alloc region before new allocations can take place. 285 void init_mutator_alloc_region(); 286 287 // It releases the mutator alloc region. 288 void release_mutator_alloc_region(); 289 290 // It initializes the GC alloc regions at the start of a GC. 291 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 292 293 // It releases the GC alloc regions at the end of a GC. 294 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 295 296 // It does any cleanup that needs to be done on the GC alloc regions 297 // before a Full GC. 298 void abandon_gc_alloc_regions(); 299 300 // Helper for monitoring and management support. 301 G1MonitoringSupport* _g1mm; 302 303 // Records whether the region at the given index is kept live by roots or 304 // references from the young generation. 305 class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> { 306 protected: 307 bool default_value() const { return false; } 308 public: 309 void clear() { G1BiasedMappedArray<bool>::clear(); } 310 void set_live(uint region) { 311 set_by_index(region, true); 312 } 313 bool is_live(uint region) { 314 return get_by_index(region); 315 } 316 }; 317 318 HumongousIsLiveBiasedMappedArray _humongous_is_live; 319 // Stores whether during humongous object registration we found candidate regions. 320 // If not, we can skip a few steps. 321 bool _has_humongous_reclaim_candidates; 322 323 volatile unsigned _gc_time_stamp; 324 325 size_t* _surviving_young_words; 326 327 G1HRPrinter _hr_printer; 328 329 void setup_surviving_young_words(); 330 void update_surviving_young_words(size_t* surv_young_words); 331 void cleanup_surviving_young_words(); 332 333 // It decides whether an explicit GC should start a concurrent cycle 334 // instead of doing a STW GC. Currently, a concurrent cycle is 335 // explicitly started if: 336 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 337 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 338 // (c) cause == _g1_humongous_allocation 339 bool should_do_concurrent_full_gc(GCCause::Cause cause); 340 341 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 342 // concurrent cycles) we have started. 343 volatile unsigned int _old_marking_cycles_started; 344 345 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 346 // concurrent cycles) we have completed. 347 volatile unsigned int _old_marking_cycles_completed; 348 349 bool _concurrent_cycle_started; 350 bool _heap_summary_sent; 351 352 // This is a non-product method that is helpful for testing. It is 353 // called at the end of a GC and artificially expands the heap by 354 // allocating a number of dead regions. This way we can induce very 355 // frequent marking cycles and stress the cleanup / concurrent 356 // cleanup code more (as all the regions that will be allocated by 357 // this method will be found dead by the marking cycle). 358 void allocate_dummy_regions() PRODUCT_RETURN; 359 360 // Clear RSets after a compaction. It also resets the GC time stamps. 361 void clear_rsets_post_compaction(); 362 363 // If the HR printer is active, dump the state of the regions in the 364 // heap after a compaction. 365 void print_hrm_post_compaction(); 366 367 double verify(bool guard, const char* msg); 368 void verify_before_gc(); 369 void verify_after_gc(); 370 371 void log_gc_header(); 372 void log_gc_footer(double pause_time_sec); 373 374 // These are macros so that, if the assert fires, we get the correct 375 // line number, file, etc. 376 377 #define heap_locking_asserts_err_msg(_extra_message_) \ 378 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 379 (_extra_message_), \ 380 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 381 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 382 BOOL_TO_STR(Thread::current()->is_VM_thread())) 383 384 #define assert_heap_locked() \ 385 do { \ 386 assert(Heap_lock->owned_by_self(), \ 387 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 388 } while (0) 389 390 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 391 do { \ 392 assert(Heap_lock->owned_by_self() || \ 393 (SafepointSynchronize::is_at_safepoint() && \ 394 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 395 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 396 "should be at a safepoint")); \ 397 } while (0) 398 399 #define assert_heap_locked_and_not_at_safepoint() \ 400 do { \ 401 assert(Heap_lock->owned_by_self() && \ 402 !SafepointSynchronize::is_at_safepoint(), \ 403 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 404 "should not be at a safepoint")); \ 405 } while (0) 406 407 #define assert_heap_not_locked() \ 408 do { \ 409 assert(!Heap_lock->owned_by_self(), \ 410 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 411 } while (0) 412 413 #define assert_heap_not_locked_and_not_at_safepoint() \ 414 do { \ 415 assert(!Heap_lock->owned_by_self() && \ 416 !SafepointSynchronize::is_at_safepoint(), \ 417 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 418 "should not be at a safepoint")); \ 419 } while (0) 420 421 #define assert_at_safepoint(_should_be_vm_thread_) \ 422 do { \ 423 assert(SafepointSynchronize::is_at_safepoint() && \ 424 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 425 heap_locking_asserts_err_msg("should be at a safepoint")); \ 426 } while (0) 427 428 #define assert_not_at_safepoint() \ 429 do { \ 430 assert(!SafepointSynchronize::is_at_safepoint(), \ 431 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 432 } while (0) 433 434 protected: 435 436 // The young region list. 437 YoungList* _young_list; 438 439 // The current policy object for the collector. 440 G1CollectorPolicy* _g1_policy; 441 442 // This is the second level of trying to allocate a new region. If 443 // new_region() didn't find a region on the free_list, this call will 444 // check whether there's anything available on the 445 // secondary_free_list and/or wait for more regions to appear on 446 // that list, if _free_regions_coming is set. 447 HeapRegion* new_region_try_secondary_free_list(bool is_old); 448 449 // Try to allocate a single non-humongous HeapRegion sufficient for 450 // an allocation of the given word_size. If do_expand is true, 451 // attempt to expand the heap if necessary to satisfy the allocation 452 // request. If the region is to be used as an old region or for a 453 // humongous object, set is_old to true. If not, to false. 454 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 455 456 // Initialize a contiguous set of free regions of length num_regions 457 // and starting at index first so that they appear as a single 458 // humongous region. 459 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 460 uint num_regions, 461 size_t word_size, 462 AllocationContext_t context); 463 464 // Attempt to allocate a humongous object of the given size. Return 465 // NULL if unsuccessful. 466 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 467 468 // The following two methods, allocate_new_tlab() and 469 // mem_allocate(), are the two main entry points from the runtime 470 // into the G1's allocation routines. They have the following 471 // assumptions: 472 // 473 // * They should both be called outside safepoints. 474 // 475 // * They should both be called without holding the Heap_lock. 476 // 477 // * All allocation requests for new TLABs should go to 478 // allocate_new_tlab(). 479 // 480 // * All non-TLAB allocation requests should go to mem_allocate(). 481 // 482 // * If either call cannot satisfy the allocation request using the 483 // current allocating region, they will try to get a new one. If 484 // this fails, they will attempt to do an evacuation pause and 485 // retry the allocation. 486 // 487 // * If all allocation attempts fail, even after trying to schedule 488 // an evacuation pause, allocate_new_tlab() will return NULL, 489 // whereas mem_allocate() will attempt a heap expansion and/or 490 // schedule a Full GC. 491 // 492 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 493 // should never be called with word_size being humongous. All 494 // humongous allocation requests should go to mem_allocate() which 495 // will satisfy them with a special path. 496 497 virtual HeapWord* allocate_new_tlab(size_t word_size); 498 499 virtual HeapWord* mem_allocate(size_t word_size, 500 bool* gc_overhead_limit_was_exceeded); 501 502 // The following three methods take a gc_count_before_ret 503 // parameter which is used to return the GC count if the method 504 // returns NULL. Given that we are required to read the GC count 505 // while holding the Heap_lock, and these paths will take the 506 // Heap_lock at some point, it's easier to get them to read the GC 507 // count while holding the Heap_lock before they return NULL instead 508 // of the caller (namely: mem_allocate()) having to also take the 509 // Heap_lock just to read the GC count. 510 511 // First-level mutator allocation attempt: try to allocate out of 512 // the mutator alloc region without taking the Heap_lock. This 513 // should only be used for non-humongous allocations. 514 inline HeapWord* attempt_allocation(size_t word_size, 515 unsigned int* gc_count_before_ret, 516 int* gclocker_retry_count_ret); 517 518 // Second-level mutator allocation attempt: take the Heap_lock and 519 // retry the allocation attempt, potentially scheduling a GC 520 // pause. This should only be used for non-humongous allocations. 521 HeapWord* attempt_allocation_slow(size_t word_size, 522 AllocationContext_t context, 523 unsigned int* gc_count_before_ret, 524 int* gclocker_retry_count_ret); 525 526 // Takes the Heap_lock and attempts a humongous allocation. It can 527 // potentially schedule a GC pause. 528 HeapWord* attempt_allocation_humongous(size_t word_size, 529 unsigned int* gc_count_before_ret, 530 int* gclocker_retry_count_ret); 531 532 // Allocation attempt that should be called during safepoints (e.g., 533 // at the end of a successful GC). expect_null_mutator_alloc_region 534 // specifies whether the mutator alloc region is expected to be NULL 535 // or not. 536 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 537 AllocationContext_t context, 538 bool expect_null_mutator_alloc_region); 539 540 // It dirties the cards that cover the block so that so that the post 541 // write barrier never queues anything when updating objects on this 542 // block. It is assumed (and in fact we assert) that the block 543 // belongs to a young region. 544 inline void dirty_young_block(HeapWord* start, size_t word_size); 545 546 // Allocate blocks during garbage collection. Will ensure an 547 // allocation region, either by picking one or expanding the 548 // heap, and then allocate a block of the given size. The block 549 // may not be a humongous - it must fit into a single heap region. 550 HeapWord* par_allocate_during_gc(in_cset_state_t dest, 551 size_t word_size, 552 AllocationContext_t context) { 553 switch (dest) { 554 case InCSetState::Young: 555 return survivor_attempt_allocation(word_size, context); 556 case InCSetState::Old: 557 return old_attempt_allocation(word_size, context); 558 default: 559 assert(false, err_msg("Unknown dest: %d", dest)); 560 break; 561 } 562 // keep some compilers happy 563 return NULL; 564 } 565 566 // Ensure that no further allocations can happen in "r", bearing in mind 567 // that parallel threads might be attempting allocations. 568 void par_allocate_remaining_space(HeapRegion* r); 569 570 // Allocation attempt during GC for a survivor object / PLAB. 571 inline HeapWord* survivor_attempt_allocation(size_t word_size, 572 AllocationContext_t context); 573 574 // Allocation attempt during GC for an old object / PLAB. 575 inline HeapWord* old_attempt_allocation(size_t word_size, 576 AllocationContext_t context); 577 578 // These methods are the "callbacks" from the G1AllocRegion class. 579 580 // For mutator alloc regions. 581 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 582 void retire_mutator_alloc_region(HeapRegion* alloc_region, 583 size_t allocated_bytes); 584 585 // For GC alloc regions. 586 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 587 in_cset_state_t dest); 588 void retire_gc_alloc_region(HeapRegion* alloc_region, 589 size_t allocated_bytes, in_cset_state_t dest); 590 591 // - if explicit_gc is true, the GC is for a System.gc() or a heap 592 // inspection request and should collect the entire heap 593 // - if clear_all_soft_refs is true, all soft references should be 594 // cleared during the GC 595 // - if explicit_gc is false, word_size describes the allocation that 596 // the GC should attempt (at least) to satisfy 597 // - it returns false if it is unable to do the collection due to the 598 // GC locker being active, true otherwise 599 bool do_collection(bool explicit_gc, 600 bool clear_all_soft_refs, 601 size_t word_size); 602 603 // Callback from VM_G1CollectFull operation. 604 // Perform a full collection. 605 virtual void do_full_collection(bool clear_all_soft_refs); 606 607 // Resize the heap if necessary after a full collection. If this is 608 // after a collect-for allocation, "word_size" is the allocation size, 609 // and will be considered part of the used portion of the heap. 610 void resize_if_necessary_after_full_collection(size_t word_size); 611 612 // Callback from VM_G1CollectForAllocation operation. 613 // This function does everything necessary/possible to satisfy a 614 // failed allocation request (including collection, expansion, etc.) 615 HeapWord* satisfy_failed_allocation(size_t word_size, 616 AllocationContext_t context, 617 bool* succeeded); 618 619 // Attempting to expand the heap sufficiently 620 // to support an allocation of the given "word_size". If 621 // successful, perform the allocation and return the address of the 622 // allocated block, or else "NULL". 623 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 624 625 // Process any reference objects discovered during 626 // an incremental evacuation pause. 627 void process_discovered_references(uint no_of_gc_workers); 628 629 // Enqueue any remaining discovered references 630 // after processing. 631 void enqueue_discovered_references(uint no_of_gc_workers); 632 633 public: 634 635 G1Allocator* allocator() { 636 return _allocator; 637 } 638 639 G1MonitoringSupport* g1mm() { 640 assert(_g1mm != NULL, "should have been initialized"); 641 return _g1mm; 642 } 643 644 // Expand the garbage-first heap by at least the given size (in bytes!). 645 // Returns true if the heap was expanded by the requested amount; 646 // false otherwise. 647 // (Rounds up to a HeapRegion boundary.) 648 bool expand(size_t expand_bytes); 649 650 // Returns the PLAB statistics for a given destination. 651 PLABStats* alloc_buffer_stats(in_cset_state_t dest) { 652 switch (dest) { 653 case InCSetState::Young: 654 return &_survivor_plab_stats; 655 case InCSetState::Old: 656 return &_old_plab_stats; 657 default: 658 assert(false, err_msg("unknown dest: %d", dest)); 659 break; 660 } 661 // keep some compilers happy 662 return NULL; 663 } 664 665 // Determines PLAB size for a given destination. 666 size_t desired_plab_sz(in_cset_state_t dest) { 667 size_t gclab_word_size = 0; 668 switch (dest) { 669 case InCSetState::Young: 670 gclab_word_size = _survivor_plab_stats.desired_plab_sz(); 671 break; 672 case InCSetState::Old: 673 gclab_word_size = _old_plab_stats.desired_plab_sz(); 674 break; 675 default: 676 assert(false, err_msg("Unknown dest: %d", dest)); 677 break; 678 } 679 680 // Prevent humongous PLAB sizes for two reasons: 681 // * PLABs are allocated using a similar paths as oops, but should 682 // never be in a humongous region 683 // * Allowing humongous PLABs needlessly churns the region free lists 684 return MIN2(_humongous_object_threshold_in_words, gclab_word_size); 685 } 686 687 inline AllocationContextStats& allocation_context_stats(); 688 689 // Do anything common to GC's. 690 virtual void gc_prologue(bool full); 691 virtual void gc_epilogue(bool full); 692 693 inline void set_humongous_is_live(oop obj); 694 695 bool humongous_is_live(uint region) { 696 return _humongous_is_live.is_live(region); 697 } 698 699 // Returns whether the given region (which must be a humongous (start) region) 700 // is to be considered conservatively live regardless of any other conditions. 701 bool humongous_region_is_always_live(uint index); 702 // Register the given region to be part of the collection set. 703 inline void register_humongous_region_with_in_cset_fast_test(uint index); 704 // Register regions with humongous objects (actually on the start region) in 705 // the in_cset_fast_test table. 706 void register_humongous_regions_with_in_cset_fast_test(); 707 // We register a region with the fast "in collection set" test. We 708 // simply set to true the array slot corresponding to this region. 709 void register_young_region_with_in_cset_fast_test(HeapRegion* r) { 710 _in_cset_fast_test.set_in_young(r->hrm_index()); 711 } 712 void register_old_region_with_in_cset_fast_test(HeapRegion* r) { 713 _in_cset_fast_test.set_in_old(r->hrm_index()); 714 } 715 716 // This is a fast test on whether a reference points into the 717 // collection set or not. Assume that the reference 718 // points into the heap. 719 inline bool in_cset_fast_test(oop obj); 720 721 void clear_cset_fast_test() { 722 _in_cset_fast_test.clear(); 723 } 724 725 // This is called at the start of either a concurrent cycle or a Full 726 // GC to update the number of old marking cycles started. 727 void increment_old_marking_cycles_started(); 728 729 // This is called at the end of either a concurrent cycle or a Full 730 // GC to update the number of old marking cycles completed. Those two 731 // can happen in a nested fashion, i.e., we start a concurrent 732 // cycle, a Full GC happens half-way through it which ends first, 733 // and then the cycle notices that a Full GC happened and ends 734 // too. The concurrent parameter is a boolean to help us do a bit 735 // tighter consistency checking in the method. If concurrent is 736 // false, the caller is the inner caller in the nesting (i.e., the 737 // Full GC). If concurrent is true, the caller is the outer caller 738 // in this nesting (i.e., the concurrent cycle). Further nesting is 739 // not currently supported. The end of this call also notifies 740 // the FullGCCount_lock in case a Java thread is waiting for a full 741 // GC to happen (e.g., it called System.gc() with 742 // +ExplicitGCInvokesConcurrent). 743 void increment_old_marking_cycles_completed(bool concurrent); 744 745 unsigned int old_marking_cycles_completed() { 746 return _old_marking_cycles_completed; 747 } 748 749 void register_concurrent_cycle_start(const Ticks& start_time); 750 void register_concurrent_cycle_end(); 751 void trace_heap_after_concurrent_cycle(); 752 753 G1YCType yc_type(); 754 755 G1HRPrinter* hr_printer() { return &_hr_printer; } 756 757 // Frees a non-humongous region by initializing its contents and 758 // adding it to the free list that's passed as a parameter (this is 759 // usually a local list which will be appended to the master free 760 // list later). The used bytes of freed regions are accumulated in 761 // pre_used. If par is true, the region's RSet will not be freed 762 // up. The assumption is that this will be done later. 763 // The locked parameter indicates if the caller has already taken 764 // care of proper synchronization. This may allow some optimizations. 765 void free_region(HeapRegion* hr, 766 FreeRegionList* free_list, 767 bool par, 768 bool locked = false); 769 770 // Frees a humongous region by collapsing it into individual regions 771 // and calling free_region() for each of them. The freed regions 772 // will be added to the free list that's passed as a parameter (this 773 // is usually a local list which will be appended to the master free 774 // list later). The used bytes of freed regions are accumulated in 775 // pre_used. If par is true, the region's RSet will not be freed 776 // up. The assumption is that this will be done later. 777 void free_humongous_region(HeapRegion* hr, 778 FreeRegionList* free_list, 779 bool par); 780 protected: 781 782 // Shrink the garbage-first heap by at most the given size (in bytes!). 783 // (Rounds down to a HeapRegion boundary.) 784 virtual void shrink(size_t expand_bytes); 785 void shrink_helper(size_t expand_bytes); 786 787 #if TASKQUEUE_STATS 788 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 789 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 790 void reset_taskqueue_stats(); 791 #endif // TASKQUEUE_STATS 792 793 // Schedule the VM operation that will do an evacuation pause to 794 // satisfy an allocation request of word_size. *succeeded will 795 // return whether the VM operation was successful (it did do an 796 // evacuation pause) or not (another thread beat us to it or the GC 797 // locker was active). Given that we should not be holding the 798 // Heap_lock when we enter this method, we will pass the 799 // gc_count_before (i.e., total_collections()) as a parameter since 800 // it has to be read while holding the Heap_lock. Currently, both 801 // methods that call do_collection_pause() release the Heap_lock 802 // before the call, so it's easy to read gc_count_before just before. 803 HeapWord* do_collection_pause(size_t word_size, 804 unsigned int gc_count_before, 805 bool* succeeded, 806 GCCause::Cause gc_cause); 807 808 // The guts of the incremental collection pause, executed by the vm 809 // thread. It returns false if it is unable to do the collection due 810 // to the GC locker being active, true otherwise 811 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 812 813 // Actually do the work of evacuating the collection set. 814 void evacuate_collection_set(EvacuationInfo& evacuation_info); 815 816 // The g1 remembered set of the heap. 817 G1RemSet* _g1_rem_set; 818 819 // A set of cards that cover the objects for which the Rsets should be updated 820 // concurrently after the collection. 821 DirtyCardQueueSet _dirty_card_queue_set; 822 823 // The closure used to refine a single card. 824 RefineCardTableEntryClosure* _refine_cte_cl; 825 826 // A DirtyCardQueueSet that is used to hold cards that contain 827 // references into the current collection set. This is used to 828 // update the remembered sets of the regions in the collection 829 // set in the event of an evacuation failure. 830 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 831 832 // After a collection pause, make the regions in the CS into free 833 // regions. 834 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 835 836 // Abandon the current collection set without recording policy 837 // statistics or updating free lists. 838 void abandon_collection_set(HeapRegion* cs_head); 839 840 // Applies "scan_non_heap_roots" to roots outside the heap, 841 // "scan_rs" to roots inside the heap (having done "set_region" to 842 // indicate the region in which the root resides), 843 // and does "scan_metadata" If "scan_rs" is 844 // NULL, then this step is skipped. The "worker_i" 845 // param is for use with parallel roots processing, and should be 846 // the "i" of the calling parallel worker thread's work(i) function. 847 // In the sequential case this param will be ignored. 848 void g1_process_roots(OopClosure* scan_non_heap_roots, 849 OopClosure* scan_non_heap_weak_roots, 850 OopsInHeapRegionClosure* scan_rs, 851 CLDClosure* scan_strong_clds, 852 CLDClosure* scan_weak_clds, 853 CodeBlobClosure* scan_strong_code, 854 uint worker_i); 855 856 // The concurrent marker (and the thread it runs in.) 857 ConcurrentMark* _cm; 858 ConcurrentMarkThread* _cmThread; 859 bool _mark_in_progress; 860 861 // The concurrent refiner. 862 ConcurrentG1Refine* _cg1r; 863 864 // The parallel task queues 865 RefToScanQueueSet *_task_queues; 866 867 // True iff a evacuation has failed in the current collection. 868 bool _evacuation_failed; 869 870 EvacuationFailedInfo* _evacuation_failed_info_array; 871 872 // Failed evacuations cause some logical from-space objects to have 873 // forwarding pointers to themselves. Reset them. 874 void remove_self_forwarding_pointers(); 875 876 // Together, these store an object with a preserved mark, and its mark value. 877 Stack<oop, mtGC> _objs_with_preserved_marks; 878 Stack<markOop, mtGC> _preserved_marks_of_objs; 879 880 // Preserve the mark of "obj", if necessary, in preparation for its mark 881 // word being overwritten with a self-forwarding-pointer. 882 void preserve_mark_if_necessary(oop obj, markOop m); 883 884 // The stack of evac-failure objects left to be scanned. 885 GrowableArray<oop>* _evac_failure_scan_stack; 886 // The closure to apply to evac-failure objects. 887 888 OopsInHeapRegionClosure* _evac_failure_closure; 889 // Set the field above. 890 void 891 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 892 _evac_failure_closure = evac_failure_closure; 893 } 894 895 // Push "obj" on the scan stack. 896 void push_on_evac_failure_scan_stack(oop obj); 897 // Process scan stack entries until the stack is empty. 898 void drain_evac_failure_scan_stack(); 899 // True iff an invocation of "drain_scan_stack" is in progress; to 900 // prevent unnecessary recursion. 901 bool _drain_in_progress; 902 903 // Do any necessary initialization for evacuation-failure handling. 904 // "cl" is the closure that will be used to process evac-failure 905 // objects. 906 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 907 // Do any necessary cleanup for evacuation-failure handling data 908 // structures. 909 void finalize_for_evac_failure(); 910 911 // An attempt to evacuate "obj" has failed; take necessary steps. 912 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 913 void handle_evacuation_failure_common(oop obj, markOop m); 914 915 #ifndef PRODUCT 916 // Support for forcing evacuation failures. Analogous to 917 // PromotionFailureALot for the other collectors. 918 919 // Records whether G1EvacuationFailureALot should be in effect 920 // for the current GC 921 bool _evacuation_failure_alot_for_current_gc; 922 923 // Used to record the GC number for interval checking when 924 // determining whether G1EvaucationFailureALot is in effect 925 // for the current GC. 926 size_t _evacuation_failure_alot_gc_number; 927 928 // Count of the number of evacuations between failures. 929 volatile size_t _evacuation_failure_alot_count; 930 931 // Set whether G1EvacuationFailureALot should be in effect 932 // for the current GC (based upon the type of GC and which 933 // command line flags are set); 934 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 935 bool during_initial_mark, 936 bool during_marking); 937 938 inline void set_evacuation_failure_alot_for_current_gc(); 939 940 // Return true if it's time to cause an evacuation failure. 941 inline bool evacuation_should_fail(); 942 943 // Reset the G1EvacuationFailureALot counters. Should be called at 944 // the end of an evacuation pause in which an evacuation failure occurred. 945 inline void reset_evacuation_should_fail(); 946 #endif // !PRODUCT 947 948 // ("Weak") Reference processing support. 949 // 950 // G1 has 2 instances of the reference processor class. One 951 // (_ref_processor_cm) handles reference object discovery 952 // and subsequent processing during concurrent marking cycles. 953 // 954 // The other (_ref_processor_stw) handles reference object 955 // discovery and processing during full GCs and incremental 956 // evacuation pauses. 957 // 958 // During an incremental pause, reference discovery will be 959 // temporarily disabled for _ref_processor_cm and will be 960 // enabled for _ref_processor_stw. At the end of the evacuation 961 // pause references discovered by _ref_processor_stw will be 962 // processed and discovery will be disabled. The previous 963 // setting for reference object discovery for _ref_processor_cm 964 // will be re-instated. 965 // 966 // At the start of marking: 967 // * Discovery by the CM ref processor is verified to be inactive 968 // and it's discovered lists are empty. 969 // * Discovery by the CM ref processor is then enabled. 970 // 971 // At the end of marking: 972 // * Any references on the CM ref processor's discovered 973 // lists are processed (possibly MT). 974 // 975 // At the start of full GC we: 976 // * Disable discovery by the CM ref processor and 977 // empty CM ref processor's discovered lists 978 // (without processing any entries). 979 // * Verify that the STW ref processor is inactive and it's 980 // discovered lists are empty. 981 // * Temporarily set STW ref processor discovery as single threaded. 982 // * Temporarily clear the STW ref processor's _is_alive_non_header 983 // field. 984 // * Finally enable discovery by the STW ref processor. 985 // 986 // The STW ref processor is used to record any discovered 987 // references during the full GC. 988 // 989 // At the end of a full GC we: 990 // * Enqueue any reference objects discovered by the STW ref processor 991 // that have non-live referents. This has the side-effect of 992 // making the STW ref processor inactive by disabling discovery. 993 // * Verify that the CM ref processor is still inactive 994 // and no references have been placed on it's discovered 995 // lists (also checked as a precondition during initial marking). 996 997 // The (stw) reference processor... 998 ReferenceProcessor* _ref_processor_stw; 999 1000 STWGCTimer* _gc_timer_stw; 1001 ConcurrentGCTimer* _gc_timer_cm; 1002 1003 G1OldTracer* _gc_tracer_cm; 1004 G1NewTracer* _gc_tracer_stw; 1005 1006 // During reference object discovery, the _is_alive_non_header 1007 // closure (if non-null) is applied to the referent object to 1008 // determine whether the referent is live. If so then the 1009 // reference object does not need to be 'discovered' and can 1010 // be treated as a regular oop. This has the benefit of reducing 1011 // the number of 'discovered' reference objects that need to 1012 // be processed. 1013 // 1014 // Instance of the is_alive closure for embedding into the 1015 // STW reference processor as the _is_alive_non_header field. 1016 // Supplying a value for the _is_alive_non_header field is 1017 // optional but doing so prevents unnecessary additions to 1018 // the discovered lists during reference discovery. 1019 G1STWIsAliveClosure _is_alive_closure_stw; 1020 1021 // The (concurrent marking) reference processor... 1022 ReferenceProcessor* _ref_processor_cm; 1023 1024 // Instance of the concurrent mark is_alive closure for embedding 1025 // into the Concurrent Marking reference processor as the 1026 // _is_alive_non_header field. Supplying a value for the 1027 // _is_alive_non_header field is optional but doing so prevents 1028 // unnecessary additions to the discovered lists during reference 1029 // discovery. 1030 G1CMIsAliveClosure _is_alive_closure_cm; 1031 1032 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1033 HeapRegion** _worker_cset_start_region; 1034 1035 // Time stamp to validate the regions recorded in the cache 1036 // used by G1CollectedHeap::start_cset_region_for_worker(). 1037 // The heap region entry for a given worker is valid iff 1038 // the associated time stamp value matches the current value 1039 // of G1CollectedHeap::_gc_time_stamp. 1040 unsigned int* _worker_cset_start_region_time_stamp; 1041 1042 enum G1H_process_roots_tasks { 1043 G1H_PS_filter_satb_buffers, 1044 G1H_PS_refProcessor_oops_do, 1045 // Leave this one last. 1046 G1H_PS_NumElements 1047 }; 1048 1049 SubTasksDone* _process_strong_tasks; 1050 1051 volatile bool _free_regions_coming; 1052 1053 public: 1054 1055 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1056 1057 void set_refine_cte_cl_concurrency(bool concurrent); 1058 1059 RefToScanQueue *task_queue(int i) const; 1060 1061 // A set of cards where updates happened during the GC 1062 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1063 1064 // A DirtyCardQueueSet that is used to hold cards that contain 1065 // references into the current collection set. This is used to 1066 // update the remembered sets of the regions in the collection 1067 // set in the event of an evacuation failure. 1068 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1069 { return _into_cset_dirty_card_queue_set; } 1070 1071 // Create a G1CollectedHeap with the specified policy. 1072 // Must call the initialize method afterwards. 1073 // May not return if something goes wrong. 1074 G1CollectedHeap(G1CollectorPolicy* policy); 1075 1076 // Initialize the G1CollectedHeap to have the initial and 1077 // maximum sizes and remembered and barrier sets 1078 // specified by the policy object. 1079 jint initialize(); 1080 1081 virtual void stop(); 1082 1083 // Return the (conservative) maximum heap alignment for any G1 heap 1084 static size_t conservative_max_heap_alignment(); 1085 1086 // Initialize weak reference processing. 1087 virtual void ref_processing_init(); 1088 1089 void set_par_threads(uint t) { 1090 SharedHeap::set_par_threads(t); 1091 // Done in SharedHeap but oddly there are 1092 // two _process_strong_tasks's in a G1CollectedHeap 1093 // so do it here too. 1094 _process_strong_tasks->set_n_threads(t); 1095 } 1096 1097 // Set _n_par_threads according to a policy TBD. 1098 void set_par_threads(); 1099 1100 void set_n_termination(int t) { 1101 _process_strong_tasks->set_n_threads(t); 1102 } 1103 1104 virtual CollectedHeap::Name kind() const { 1105 return CollectedHeap::G1CollectedHeap; 1106 } 1107 1108 // The current policy object for the collector. 1109 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1110 1111 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1112 1113 // Adaptive size policy. No such thing for g1. 1114 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1115 1116 // The rem set and barrier set. 1117 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1118 1119 unsigned get_gc_time_stamp() { 1120 return _gc_time_stamp; 1121 } 1122 1123 inline void reset_gc_time_stamp(); 1124 1125 void check_gc_time_stamps() PRODUCT_RETURN; 1126 1127 inline void increment_gc_time_stamp(); 1128 1129 // Reset the given region's GC timestamp. If it's starts humongous, 1130 // also reset the GC timestamp of its corresponding 1131 // continues humongous regions too. 1132 void reset_gc_time_stamps(HeapRegion* hr); 1133 1134 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1135 DirtyCardQueue* into_cset_dcq, 1136 bool concurrent, uint worker_i); 1137 1138 // The shared block offset table array. 1139 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1140 1141 // Reference Processing accessors 1142 1143 // The STW reference processor.... 1144 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1145 1146 // The Concurrent Marking reference processor... 1147 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1148 1149 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1150 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1151 1152 virtual size_t capacity() const; 1153 virtual size_t used() const; 1154 // This should be called when we're not holding the heap lock. The 1155 // result might be a bit inaccurate. 1156 size_t used_unlocked() const; 1157 size_t recalculate_used() const; 1158 1159 // These virtual functions do the actual allocation. 1160 // Some heaps may offer a contiguous region for shared non-blocking 1161 // allocation, via inlined code (by exporting the address of the top and 1162 // end fields defining the extent of the contiguous allocation region.) 1163 // But G1CollectedHeap doesn't yet support this. 1164 1165 virtual bool is_maximal_no_gc() const { 1166 return _hrm.available() == 0; 1167 } 1168 1169 // The current number of regions in the heap. 1170 uint num_regions() const { return _hrm.length(); } 1171 1172 // The max number of regions in the heap. 1173 uint max_regions() const { return _hrm.max_length(); } 1174 1175 // The number of regions that are completely free. 1176 uint num_free_regions() const { return _hrm.num_free_regions(); } 1177 1178 // The number of regions that are not completely free. 1179 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1180 1181 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1182 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1183 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1184 void verify_dirty_young_regions() PRODUCT_RETURN; 1185 1186 #ifndef PRODUCT 1187 // Make sure that the given bitmap has no marked objects in the 1188 // range [from,limit). If it does, print an error message and return 1189 // false. Otherwise, just return true. bitmap_name should be "prev" 1190 // or "next". 1191 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1192 HeapWord* from, HeapWord* limit); 1193 1194 // Verify that the prev / next bitmap range [tams,end) for the given 1195 // region has no marks. Return true if all is well, false if errors 1196 // are detected. 1197 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1198 #endif // PRODUCT 1199 1200 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1201 // the given region do not have any spurious marks. If errors are 1202 // detected, print appropriate error messages and crash. 1203 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1204 1205 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1206 // have any spurious marks. If errors are detected, print 1207 // appropriate error messages and crash. 1208 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1209 1210 // Do sanity check on the contents of the in-cset fast test table. 1211 bool check_cset_fast_test(); 1212 1213 // verify_region_sets() performs verification over the region 1214 // lists. It will be compiled in the product code to be used when 1215 // necessary (i.e., during heap verification). 1216 void verify_region_sets(); 1217 1218 // verify_region_sets_optional() is planted in the code for 1219 // list verification in non-product builds (and it can be enabled in 1220 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1221 #if HEAP_REGION_SET_FORCE_VERIFY 1222 void verify_region_sets_optional() { 1223 verify_region_sets(); 1224 } 1225 #else // HEAP_REGION_SET_FORCE_VERIFY 1226 void verify_region_sets_optional() { } 1227 #endif // HEAP_REGION_SET_FORCE_VERIFY 1228 1229 #ifdef ASSERT 1230 bool is_on_master_free_list(HeapRegion* hr) { 1231 return _hrm.is_free(hr); 1232 } 1233 #endif // ASSERT 1234 1235 // Wrapper for the region list operations that can be called from 1236 // methods outside this class. 1237 1238 void secondary_free_list_add(FreeRegionList* list) { 1239 _secondary_free_list.add_ordered(list); 1240 } 1241 1242 void append_secondary_free_list() { 1243 _hrm.insert_list_into_free_list(&_secondary_free_list); 1244 } 1245 1246 void append_secondary_free_list_if_not_empty_with_lock() { 1247 // If the secondary free list looks empty there's no reason to 1248 // take the lock and then try to append it. 1249 if (!_secondary_free_list.is_empty()) { 1250 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1251 append_secondary_free_list(); 1252 } 1253 } 1254 1255 inline void old_set_remove(HeapRegion* hr); 1256 1257 size_t non_young_capacity_bytes() { 1258 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1259 } 1260 1261 void set_free_regions_coming(); 1262 void reset_free_regions_coming(); 1263 bool free_regions_coming() { return _free_regions_coming; } 1264 void wait_while_free_regions_coming(); 1265 1266 // Determine whether the given region is one that we are using as an 1267 // old GC alloc region. 1268 bool is_old_gc_alloc_region(HeapRegion* hr) { 1269 return _allocator->is_retained_old_region(hr); 1270 } 1271 1272 // Perform a collection of the heap; intended for use in implementing 1273 // "System.gc". This probably implies as full a collection as the 1274 // "CollectedHeap" supports. 1275 virtual void collect(GCCause::Cause cause); 1276 1277 // The same as above but assume that the caller holds the Heap_lock. 1278 void collect_locked(GCCause::Cause cause); 1279 1280 virtual bool copy_allocation_context_stats(const jint* contexts, 1281 jlong* totals, 1282 jbyte* accuracy, 1283 jint len); 1284 1285 // True iff an evacuation has failed in the most-recent collection. 1286 bool evacuation_failed() { return _evacuation_failed; } 1287 1288 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1289 void prepend_to_freelist(FreeRegionList* list); 1290 void decrement_summary_bytes(size_t bytes); 1291 1292 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1293 virtual bool is_in(const void* p) const; 1294 #ifdef ASSERT 1295 // Returns whether p is in one of the available areas of the heap. Slow but 1296 // extensive version. 1297 bool is_in_exact(const void* p) const; 1298 #endif 1299 1300 // Return "TRUE" iff the given object address is within the collection 1301 // set. Slow implementation. 1302 inline bool obj_in_cs(oop obj); 1303 1304 inline bool is_in_cset(oop obj); 1305 1306 inline bool is_in_cset_or_humongous(const oop obj); 1307 1308 private: 1309 // Instances of this class are used for quick tests on whether a reference points 1310 // into the collection set and into which generation or is a humongous object 1311 // 1312 // Each of the array's elements indicates whether the corresponding region is in 1313 // the collection set and if so in which generation, or a humongous region. 1314 // 1315 // We use this to speed up reference processing during young collection and 1316 // quickly reclaim humongous objects. For the latter, by making a humongous region 1317 // succeed this test, we sort-of add it to the collection set. During the reference 1318 // iteration closures, when we see a humongous region, we then simply mark it as 1319 // referenced, i.e. live. 1320 class G1InCSetStateFastTestBiasedMappedArray : public G1BiasedMappedArray<in_cset_state_t> { 1321 protected: 1322 in_cset_state_t default_value() const { return InCSetState::NotInCSet; } 1323 public: 1324 void set_humongous(uintptr_t index) { 1325 assert(get_by_index(index) == default_value(), "should be default"); 1326 set_by_index(index, InCSetState::humongous()); 1327 } 1328 1329 void clear_humongous(uintptr_t index) { 1330 set_by_index(index, InCSetState::NotInCSet); 1331 } 1332 1333 void set_in_young(uintptr_t index) { 1334 assert(get_by_index(index) == default_value(), "should be default"); 1335 set_by_index(index, InCSetState::Young); 1336 } 1337 1338 void set_in_old(uintptr_t index) { 1339 assert(get_by_index(index) == default_value(), "should be default"); 1340 set_by_index(index, InCSetState::Old); 1341 } 1342 1343 bool is_in_cset_or_humongous(HeapWord* addr) const { return InCSetState::is_in_cset_or_humongous(at(addr)); } 1344 bool is_in_cset(HeapWord* addr) const { return InCSetState::is_in_cset(at(addr)); } 1345 in_cset_state_t at(HeapWord* addr) const { return (in_cset_state_t) get_by_address(addr); } 1346 void clear() { G1BiasedMappedArray<in_cset_state_t>::clear(); } 1347 }; 1348 1349 // This array is used for a quick test on whether a reference points into 1350 // the collection set or not. Each of the array's elements denotes whether the 1351 // corresponding region is in the collection set or not. 1352 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1353 1354 public: 1355 1356 inline in_cset_state_t in_cset_state(const oop obj); 1357 1358 // Return "TRUE" iff the given object address is in the reserved 1359 // region of g1. 1360 bool is_in_g1_reserved(const void* p) const { 1361 return _hrm.reserved().contains(p); 1362 } 1363 1364 // Returns a MemRegion that corresponds to the space that has been 1365 // reserved for the heap 1366 MemRegion g1_reserved() const { 1367 return _hrm.reserved(); 1368 } 1369 1370 virtual bool is_in_closed_subset(const void* p) const; 1371 1372 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1373 return (G1SATBCardTableLoggingModRefBS*) barrier_set(); 1374 } 1375 1376 // This resets the card table to all zeros. It is used after 1377 // a collection pause which used the card table to claim cards. 1378 void cleanUpCardTable(); 1379 1380 // Iteration functions. 1381 1382 // Iterate over all the ref-containing fields of all objects, calling 1383 // "cl.do_oop" on each. 1384 virtual void oop_iterate(ExtendedOopClosure* cl); 1385 1386 // Iterate over all objects, calling "cl.do_object" on each. 1387 virtual void object_iterate(ObjectClosure* cl); 1388 1389 virtual void safe_object_iterate(ObjectClosure* cl) { 1390 object_iterate(cl); 1391 } 1392 1393 // Iterate over all spaces in use in the heap, in ascending address order. 1394 virtual void space_iterate(SpaceClosure* cl); 1395 1396 // Iterate over heap regions, in address order, terminating the 1397 // iteration early if the "doHeapRegion" method returns "true". 1398 void heap_region_iterate(HeapRegionClosure* blk) const; 1399 1400 // Return the region with the given index. It assumes the index is valid. 1401 inline HeapRegion* region_at(uint index) const; 1402 1403 // Calculate the region index of the given address. Given address must be 1404 // within the heap. 1405 inline uint addr_to_region(HeapWord* addr) const; 1406 1407 inline HeapWord* bottom_addr_for_region(uint index) const; 1408 1409 // Iterate over the heap regions in parallel. Assumes that this will be called 1410 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1411 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1412 // to each of the regions, by attempting to claim the region using the 1413 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1414 // region. The concurrent argument should be set to true if iteration is 1415 // performed concurrently, during which no assumptions are made for consistent 1416 // attributes of the heap regions (as they might be modified while iterating). 1417 void heap_region_par_iterate(HeapRegionClosure* cl, 1418 uint worker_id, 1419 HeapRegionClaimer* hrclaimer, 1420 bool concurrent = false) const; 1421 1422 // Clear the cached cset start regions and (more importantly) 1423 // the time stamps. Called when we reset the GC time stamp. 1424 void clear_cset_start_regions(); 1425 1426 // Given the id of a worker, obtain or calculate a suitable 1427 // starting region for iterating over the current collection set. 1428 HeapRegion* start_cset_region_for_worker(uint worker_i); 1429 1430 // Iterate over the regions (if any) in the current collection set. 1431 void collection_set_iterate(HeapRegionClosure* blk); 1432 1433 // As above but starting from region r 1434 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1435 1436 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1437 1438 // A CollectedHeap will contain some number of spaces. This finds the 1439 // space containing a given address, or else returns NULL. 1440 virtual Space* space_containing(const void* addr) const; 1441 1442 // Returns the HeapRegion that contains addr. addr must not be NULL. 1443 template <class T> 1444 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1445 1446 // Returns the HeapRegion that contains addr. addr must not be NULL. 1447 // If addr is within a humongous continues region, it returns its humongous start region. 1448 template <class T> 1449 inline HeapRegion* heap_region_containing(const T addr) const; 1450 1451 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1452 // each address in the (reserved) heap is a member of exactly 1453 // one block. The defining characteristic of a block is that it is 1454 // possible to find its size, and thus to progress forward to the next 1455 // block. (Blocks may be of different sizes.) Thus, blocks may 1456 // represent Java objects, or they might be free blocks in a 1457 // free-list-based heap (or subheap), as long as the two kinds are 1458 // distinguishable and the size of each is determinable. 1459 1460 // Returns the address of the start of the "block" that contains the 1461 // address "addr". We say "blocks" instead of "object" since some heaps 1462 // may not pack objects densely; a chunk may either be an object or a 1463 // non-object. 1464 virtual HeapWord* block_start(const void* addr) const; 1465 1466 // Requires "addr" to be the start of a chunk, and returns its size. 1467 // "addr + size" is required to be the start of a new chunk, or the end 1468 // of the active area of the heap. 1469 virtual size_t block_size(const HeapWord* addr) const; 1470 1471 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1472 // the block is an object. 1473 virtual bool block_is_obj(const HeapWord* addr) const; 1474 1475 // Does this heap support heap inspection? (+PrintClassHistogram) 1476 virtual bool supports_heap_inspection() const { return true; } 1477 1478 // Section on thread-local allocation buffers (TLABs) 1479 // See CollectedHeap for semantics. 1480 1481 bool supports_tlab_allocation() const; 1482 size_t tlab_capacity(Thread* ignored) const; 1483 size_t tlab_used(Thread* ignored) const; 1484 size_t max_tlab_size() const; 1485 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1486 1487 // Can a compiler initialize a new object without store barriers? 1488 // This permission only extends from the creation of a new object 1489 // via a TLAB up to the first subsequent safepoint. If such permission 1490 // is granted for this heap type, the compiler promises to call 1491 // defer_store_barrier() below on any slow path allocation of 1492 // a new object for which such initializing store barriers will 1493 // have been elided. G1, like CMS, allows this, but should be 1494 // ready to provide a compensating write barrier as necessary 1495 // if that storage came out of a non-young region. The efficiency 1496 // of this implementation depends crucially on being able to 1497 // answer very efficiently in constant time whether a piece of 1498 // storage in the heap comes from a young region or not. 1499 // See ReduceInitialCardMarks. 1500 virtual bool can_elide_tlab_store_barriers() const { 1501 return true; 1502 } 1503 1504 virtual bool card_mark_must_follow_store() const { 1505 return true; 1506 } 1507 1508 inline bool is_in_young(const oop obj); 1509 1510 #ifdef ASSERT 1511 virtual bool is_in_partial_collection(const void* p); 1512 #endif 1513 1514 virtual bool is_scavengable(const void* addr); 1515 1516 // We don't need barriers for initializing stores to objects 1517 // in the young gen: for the SATB pre-barrier, there is no 1518 // pre-value that needs to be remembered; for the remembered-set 1519 // update logging post-barrier, we don't maintain remembered set 1520 // information for young gen objects. 1521 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1522 1523 // Returns "true" iff the given word_size is "very large". 1524 static bool is_humongous(size_t word_size) { 1525 // Note this has to be strictly greater-than as the TLABs 1526 // are capped at the humongous threshold and we want to 1527 // ensure that we don't try to allocate a TLAB as 1528 // humongous and that we don't allocate a humongous 1529 // object in a TLAB. 1530 return word_size > _humongous_object_threshold_in_words; 1531 } 1532 1533 // Update mod union table with the set of dirty cards. 1534 void updateModUnion(); 1535 1536 // Set the mod union bits corresponding to the given memRegion. Note 1537 // that this is always a safe operation, since it doesn't clear any 1538 // bits. 1539 void markModUnionRange(MemRegion mr); 1540 1541 // Records the fact that a marking phase is no longer in progress. 1542 void set_marking_complete() { 1543 _mark_in_progress = false; 1544 } 1545 void set_marking_started() { 1546 _mark_in_progress = true; 1547 } 1548 bool mark_in_progress() { 1549 return _mark_in_progress; 1550 } 1551 1552 // Print the maximum heap capacity. 1553 virtual size_t max_capacity() const; 1554 1555 virtual jlong millis_since_last_gc(); 1556 1557 1558 // Convenience function to be used in situations where the heap type can be 1559 // asserted to be this type. 1560 static G1CollectedHeap* heap(); 1561 1562 void set_region_short_lived_locked(HeapRegion* hr); 1563 // add appropriate methods for any other surv rate groups 1564 1565 YoungList* young_list() const { return _young_list; } 1566 1567 // debugging 1568 bool check_young_list_well_formed() { 1569 return _young_list->check_list_well_formed(); 1570 } 1571 1572 bool check_young_list_empty(bool check_heap, 1573 bool check_sample = true); 1574 1575 // *** Stuff related to concurrent marking. It's not clear to me that so 1576 // many of these need to be public. 1577 1578 // The functions below are helper functions that a subclass of 1579 // "CollectedHeap" can use in the implementation of its virtual 1580 // functions. 1581 // This performs a concurrent marking of the live objects in a 1582 // bitmap off to the side. 1583 void doConcurrentMark(); 1584 1585 bool isMarkedPrev(oop obj) const; 1586 bool isMarkedNext(oop obj) const; 1587 1588 // Determine if an object is dead, given the object and also 1589 // the region to which the object belongs. An object is dead 1590 // iff a) it was not allocated since the last mark and b) it 1591 // is not marked. 1592 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1593 return 1594 !hr->obj_allocated_since_prev_marking(obj) && 1595 !isMarkedPrev(obj); 1596 } 1597 1598 // This function returns true when an object has been 1599 // around since the previous marking and hasn't yet 1600 // been marked during this marking. 1601 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1602 return 1603 !hr->obj_allocated_since_next_marking(obj) && 1604 !isMarkedNext(obj); 1605 } 1606 1607 // Determine if an object is dead, given only the object itself. 1608 // This will find the region to which the object belongs and 1609 // then call the region version of the same function. 1610 1611 // Added if it is NULL it isn't dead. 1612 1613 inline bool is_obj_dead(const oop obj) const; 1614 1615 inline bool is_obj_ill(const oop obj) const; 1616 1617 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1618 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1619 bool is_marked(oop obj, VerifyOption vo); 1620 const char* top_at_mark_start_str(VerifyOption vo); 1621 1622 ConcurrentMark* concurrent_mark() const { return _cm; } 1623 1624 // Refinement 1625 1626 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1627 1628 // The dirty cards region list is used to record a subset of regions 1629 // whose cards need clearing. The list if populated during the 1630 // remembered set scanning and drained during the card table 1631 // cleanup. Although the methods are reentrant, population/draining 1632 // phases must not overlap. For synchronization purposes the last 1633 // element on the list points to itself. 1634 HeapRegion* _dirty_cards_region_list; 1635 void push_dirty_cards_region(HeapRegion* hr); 1636 HeapRegion* pop_dirty_cards_region(); 1637 1638 // Optimized nmethod scanning support routines 1639 1640 // Register the given nmethod with the G1 heap. 1641 virtual void register_nmethod(nmethod* nm); 1642 1643 // Unregister the given nmethod from the G1 heap. 1644 virtual void unregister_nmethod(nmethod* nm); 1645 1646 // Free up superfluous code root memory. 1647 void purge_code_root_memory(); 1648 1649 // Rebuild the strong code root lists for each region 1650 // after a full GC. 1651 void rebuild_strong_code_roots(); 1652 1653 // Delete entries for dead interned string and clean up unreferenced symbols 1654 // in symbol table, possibly in parallel. 1655 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1656 1657 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1658 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1659 1660 // Redirty logged cards in the refinement queue. 1661 void redirty_logged_cards(); 1662 // Verification 1663 1664 // The following is just to alert the verification code 1665 // that a full collection has occurred and that the 1666 // remembered sets are no longer up to date. 1667 bool _full_collection; 1668 void set_full_collection() { _full_collection = true;} 1669 void clear_full_collection() {_full_collection = false;} 1670 bool full_collection() {return _full_collection;} 1671 1672 // Perform any cleanup actions necessary before allowing a verification. 1673 virtual void prepare_for_verify(); 1674 1675 // Perform verification. 1676 1677 // vo == UsePrevMarking -> use "prev" marking information, 1678 // vo == UseNextMarking -> use "next" marking information 1679 // vo == UseMarkWord -> use the mark word in the object header 1680 // 1681 // NOTE: Only the "prev" marking information is guaranteed to be 1682 // consistent most of the time, so most calls to this should use 1683 // vo == UsePrevMarking. 1684 // Currently, there is only one case where this is called with 1685 // vo == UseNextMarking, which is to verify the "next" marking 1686 // information at the end of remark. 1687 // Currently there is only one place where this is called with 1688 // vo == UseMarkWord, which is to verify the marking during a 1689 // full GC. 1690 void verify(bool silent, VerifyOption vo); 1691 1692 // Override; it uses the "prev" marking information 1693 virtual void verify(bool silent); 1694 1695 // The methods below are here for convenience and dispatch the 1696 // appropriate method depending on value of the given VerifyOption 1697 // parameter. The values for that parameter, and their meanings, 1698 // are the same as those above. 1699 1700 bool is_obj_dead_cond(const oop obj, 1701 const HeapRegion* hr, 1702 const VerifyOption vo) const; 1703 1704 bool is_obj_dead_cond(const oop obj, 1705 const VerifyOption vo) const; 1706 1707 // Printing 1708 1709 virtual void print_on(outputStream* st) const; 1710 virtual void print_extended_on(outputStream* st) const; 1711 virtual void print_on_error(outputStream* st) const; 1712 1713 virtual void print_gc_threads_on(outputStream* st) const; 1714 virtual void gc_threads_do(ThreadClosure* tc) const; 1715 1716 // Override 1717 void print_tracing_info() const; 1718 1719 // The following two methods are helpful for debugging RSet issues. 1720 void print_cset_rsets() PRODUCT_RETURN; 1721 void print_all_rsets() PRODUCT_RETURN; 1722 1723 public: 1724 size_t pending_card_num(); 1725 size_t cards_scanned(); 1726 1727 protected: 1728 size_t _max_heap_capacity; 1729 }; 1730 1731 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP