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/concurrentMark.hpp" 29 #include "gc_implementation/g1/evacuationInfo.hpp" 30 #include "gc_implementation/g1/g1AllocRegion.hpp" 31 #include "gc_implementation/g1/g1BiasedArray.hpp" 32 #include "gc_implementation/g1/g1HRPrinter.hpp" 33 #include "gc_implementation/g1/g1MonitoringSupport.hpp" 34 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp" 35 #include "gc_implementation/g1/g1YCTypes.hpp" 36 #include "gc_implementation/g1/heapRegionSeq.hpp" 37 #include "gc_implementation/g1/heapRegionSet.hpp" 38 #include "gc_implementation/shared/hSpaceCounters.hpp" 39 #include "gc_implementation/shared/parGCAllocBuffer.hpp" 40 #include "memory/barrierSet.hpp" 41 #include "memory/memRegion.hpp" 42 #include "memory/sharedHeap.hpp" 43 #include "utilities/stack.hpp" 44 45 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 46 // It uses the "Garbage First" heap organization and algorithm, which 47 // may combine concurrent marking with parallel, incremental compaction of 48 // heap subsets that will yield large amounts of garbage. 49 50 // Forward declarations 51 class HeapRegion; 52 class HRRSCleanupTask; 53 class GenerationSpec; 54 class OopsInHeapRegionClosure; 55 class G1KlassScanClosure; 56 class G1ScanHeapEvacClosure; 57 class ObjectClosure; 58 class SpaceClosure; 59 class CompactibleSpaceClosure; 60 class Space; 61 class G1CollectorPolicy; 62 class GenRemSet; 63 class G1RemSet; 64 class HeapRegionRemSetIterator; 65 class ConcurrentMark; 66 class ConcurrentMarkThread; 67 class ConcurrentG1Refine; 68 class ConcurrentGCTimer; 69 class GenerationCounters; 70 class STWGCTimer; 71 class G1NewTracer; 72 class G1OldTracer; 73 class EvacuationFailedInfo; 74 class nmethod; 75 class Ticks; 76 77 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 78 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 79 80 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 81 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 82 83 enum GCAllocPurpose { 84 GCAllocForTenured, 85 GCAllocForSurvived, 86 GCAllocPurposeCount 87 }; 88 89 class YoungList : public CHeapObj<mtGC> { 90 private: 91 G1CollectedHeap* _g1h; 92 93 HeapRegion* _head; 94 95 HeapRegion* _survivor_head; 96 HeapRegion* _survivor_tail; 97 98 HeapRegion* _curr; 99 100 uint _length; 101 uint _survivor_length; 102 103 size_t _last_sampled_rs_lengths; 104 size_t _sampled_rs_lengths; 105 106 void empty_list(HeapRegion* list); 107 108 public: 109 YoungList(G1CollectedHeap* g1h); 110 111 void push_region(HeapRegion* hr); 112 void add_survivor_region(HeapRegion* hr); 113 114 void empty_list(); 115 bool is_empty() { return _length == 0; } 116 uint length() { return _length; } 117 uint survivor_length() { return _survivor_length; } 118 119 // Currently we do not keep track of the used byte sum for the 120 // young list and the survivors and it'd be quite a lot of work to 121 // do so. When we'll eventually replace the young list with 122 // instances of HeapRegionLinkedList we'll get that for free. So, 123 // we'll report the more accurate information then. 124 size_t eden_used_bytes() { 125 assert(length() >= survivor_length(), "invariant"); 126 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 127 } 128 size_t survivor_used_bytes() { 129 return (size_t) survivor_length() * HeapRegion::GrainBytes; 130 } 131 132 void rs_length_sampling_init(); 133 bool rs_length_sampling_more(); 134 void rs_length_sampling_next(); 135 136 void reset_sampled_info() { 137 _last_sampled_rs_lengths = 0; 138 } 139 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 140 141 // for development purposes 142 void reset_auxilary_lists(); 143 void clear() { _head = NULL; _length = 0; } 144 145 void clear_survivors() { 146 _survivor_head = NULL; 147 _survivor_tail = NULL; 148 _survivor_length = 0; 149 } 150 151 HeapRegion* first_region() { return _head; } 152 HeapRegion* first_survivor_region() { return _survivor_head; } 153 HeapRegion* last_survivor_region() { return _survivor_tail; } 154 155 // debugging 156 bool check_list_well_formed(); 157 bool check_list_empty(bool check_sample = true); 158 void print(); 159 }; 160 161 class MutatorAllocRegion : public G1AllocRegion { 162 protected: 163 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 164 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 165 public: 166 MutatorAllocRegion() 167 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 168 }; 169 170 class SurvivorGCAllocRegion : public G1AllocRegion { 171 protected: 172 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 173 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 174 public: 175 SurvivorGCAllocRegion() 176 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { } 177 }; 178 179 class OldGCAllocRegion : public G1AllocRegion { 180 protected: 181 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 182 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 183 public: 184 OldGCAllocRegion() 185 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { } 186 }; 187 188 // The G1 STW is alive closure. 189 // An instance is embedded into the G1CH and used as the 190 // (optional) _is_alive_non_header closure in the STW 191 // reference processor. It is also extensively used during 192 // reference processing during STW evacuation pauses. 193 class G1STWIsAliveClosure: public BoolObjectClosure { 194 G1CollectedHeap* _g1; 195 public: 196 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 197 bool do_object_b(oop p); 198 }; 199 200 // Instances of this class are used for quick tests on whether a reference points 201 // into the collection set. Each of the array's elements denotes whether the 202 // corresponding region is in the collection set. 203 class G1FastCSetBiasedMappedArray : public G1BiasedMappedArray<bool> { 204 protected: 205 bool default_value() const { return false; } 206 public: 207 void clear() { G1BiasedMappedArray<bool>::clear(); } 208 }; 209 210 class RefineCardTableEntryClosure; 211 212 class G1CollectedHeap : public SharedHeap { 213 friend class VM_CollectForMetadataAllocation; 214 friend class VM_G1CollectForAllocation; 215 friend class VM_G1CollectFull; 216 friend class VM_G1IncCollectionPause; 217 friend class VMStructs; 218 friend class MutatorAllocRegion; 219 friend class SurvivorGCAllocRegion; 220 friend class OldGCAllocRegion; 221 222 // Closures used in implementation. 223 template <G1Barrier barrier, G1Mark do_mark_object> 224 friend class G1ParCopyClosure; 225 friend class G1IsAliveClosure; 226 friend class G1EvacuateFollowersClosure; 227 friend class G1ParScanThreadState; 228 friend class G1ParScanClosureSuper; 229 friend class G1ParEvacuateFollowersClosure; 230 friend class G1ParTask; 231 friend class G1FreeGarbageRegionClosure; 232 friend class RefineCardTableEntryClosure; 233 friend class G1PrepareCompactClosure; 234 friend class RegionSorter; 235 friend class RegionResetter; 236 friend class CountRCClosure; 237 friend class EvacPopObjClosure; 238 friend class G1ParCleanupCTTask; 239 240 // Other related classes. 241 friend class G1MarkSweep; 242 243 private: 244 // The one and only G1CollectedHeap, so static functions can find it. 245 static G1CollectedHeap* _g1h; 246 247 static size_t _humongous_object_threshold_in_words; 248 249 // Storage for the G1 heap. 250 VirtualSpace _g1_storage; 251 MemRegion _g1_reserved; 252 253 // The part of _g1_storage that is currently committed. 254 MemRegion _g1_committed; 255 256 // The master free list. It will satisfy all new region allocations. 257 FreeRegionList _free_list; 258 259 // The secondary free list which contains regions that have been 260 // freed up during the cleanup process. This will be appended to the 261 // master free list when appropriate. 262 FreeRegionList _secondary_free_list; 263 264 // It keeps track of the old regions. 265 HeapRegionSet _old_set; 266 267 // It keeps track of the humongous regions. 268 HeapRegionSet _humongous_set; 269 270 // The number of regions we could create by expansion. 271 uint _expansion_regions; 272 273 // The block offset table for the G1 heap. 274 G1BlockOffsetSharedArray* _bot_shared; 275 276 // Tears down the region sets / lists so that they are empty and the 277 // regions on the heap do not belong to a region set / list. The 278 // only exception is the humongous set which we leave unaltered. If 279 // free_list_only is true, it will only tear down the master free 280 // list. It is called before a Full GC (free_list_only == false) or 281 // before heap shrinking (free_list_only == true). 282 void tear_down_region_sets(bool free_list_only); 283 284 // Rebuilds the region sets / lists so that they are repopulated to 285 // reflect the contents of the heap. The only exception is the 286 // humongous set which was not torn down in the first place. If 287 // free_list_only is true, it will only rebuild the master free 288 // list. It is called after a Full GC (free_list_only == false) or 289 // after heap shrinking (free_list_only == true). 290 void rebuild_region_sets(bool free_list_only); 291 292 // The sequence of all heap regions in the heap. 293 HeapRegionSeq _hrs; 294 295 // Alloc region used to satisfy mutator allocation requests. 296 MutatorAllocRegion _mutator_alloc_region; 297 298 // Alloc region used to satisfy allocation requests by the GC for 299 // survivor objects. 300 SurvivorGCAllocRegion _survivor_gc_alloc_region; 301 302 // PLAB sizing policy for survivors. 303 PLABStats _survivor_plab_stats; 304 305 // Alloc region used to satisfy allocation requests by the GC for 306 // old objects. 307 OldGCAllocRegion _old_gc_alloc_region; 308 309 // PLAB sizing policy for tenured objects. 310 PLABStats _old_plab_stats; 311 312 PLABStats* stats_for_purpose(GCAllocPurpose purpose) { 313 PLABStats* stats = NULL; 314 315 switch (purpose) { 316 case GCAllocForSurvived: 317 stats = &_survivor_plab_stats; 318 break; 319 case GCAllocForTenured: 320 stats = &_old_plab_stats; 321 break; 322 default: 323 assert(false, "unrecognized GCAllocPurpose"); 324 } 325 326 return stats; 327 } 328 329 // The last old region we allocated to during the last GC. 330 // Typically, it is not full so we should re-use it during the next GC. 331 HeapRegion* _retained_old_gc_alloc_region; 332 333 // It specifies whether we should attempt to expand the heap after a 334 // region allocation failure. If heap expansion fails we set this to 335 // false so that we don't re-attempt the heap expansion (it's likely 336 // that subsequent expansion attempts will also fail if one fails). 337 // Currently, it is only consulted during GC and it's reset at the 338 // start of each GC. 339 bool _expand_heap_after_alloc_failure; 340 341 // It resets the mutator alloc region before new allocations can take place. 342 void init_mutator_alloc_region(); 343 344 // It releases the mutator alloc region. 345 void release_mutator_alloc_region(); 346 347 // It initializes the GC alloc regions at the start of a GC. 348 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 349 350 // Setup the retained old gc alloc region as the currrent old gc alloc region. 351 void use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info); 352 353 // It releases the GC alloc regions at the end of a GC. 354 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 355 356 // It does any cleanup that needs to be done on the GC alloc regions 357 // before a Full GC. 358 void abandon_gc_alloc_regions(); 359 360 // Helper for monitoring and management support. 361 G1MonitoringSupport* _g1mm; 362 363 // Determines PLAB size for a particular allocation purpose. 364 size_t desired_plab_sz(GCAllocPurpose purpose); 365 366 // Outside of GC pauses, the number of bytes used in all regions other 367 // than the current allocation region. 368 size_t _summary_bytes_used; 369 370 // This array is used for a quick test on whether a reference points into 371 // the collection set or not. Each of the array's elements denotes whether the 372 // corresponding region is in the collection set or not. 373 G1FastCSetBiasedMappedArray _in_cset_fast_test; 374 375 volatile unsigned _gc_time_stamp; 376 377 size_t* _surviving_young_words; 378 379 G1HRPrinter _hr_printer; 380 381 void setup_surviving_young_words(); 382 void update_surviving_young_words(size_t* surv_young_words); 383 void cleanup_surviving_young_words(); 384 385 // It decides whether an explicit GC should start a concurrent cycle 386 // instead of doing a STW GC. Currently, a concurrent cycle is 387 // explicitly started if: 388 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 389 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 390 // (c) cause == _g1_humongous_allocation 391 bool should_do_concurrent_full_gc(GCCause::Cause cause); 392 393 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 394 // concurrent cycles) we have started. 395 volatile unsigned int _old_marking_cycles_started; 396 397 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 398 // concurrent cycles) we have completed. 399 volatile unsigned int _old_marking_cycles_completed; 400 401 bool _concurrent_cycle_started; 402 403 // This is a non-product method that is helpful for testing. It is 404 // called at the end of a GC and artificially expands the heap by 405 // allocating a number of dead regions. This way we can induce very 406 // frequent marking cycles and stress the cleanup / concurrent 407 // cleanup code more (as all the regions that will be allocated by 408 // this method will be found dead by the marking cycle). 409 void allocate_dummy_regions() PRODUCT_RETURN; 410 411 // Clear RSets after a compaction. It also resets the GC time stamps. 412 void clear_rsets_post_compaction(); 413 414 // If the HR printer is active, dump the state of the regions in the 415 // heap after a compaction. 416 void print_hrs_post_compaction(); 417 418 double verify(bool guard, const char* msg); 419 void verify_before_gc(); 420 void verify_after_gc(); 421 422 void log_gc_header(); 423 void log_gc_footer(double pause_time_sec); 424 425 // These are macros so that, if the assert fires, we get the correct 426 // line number, file, etc. 427 428 #define heap_locking_asserts_err_msg(_extra_message_) \ 429 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 430 (_extra_message_), \ 431 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 432 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 433 BOOL_TO_STR(Thread::current()->is_VM_thread())) 434 435 #define assert_heap_locked() \ 436 do { \ 437 assert(Heap_lock->owned_by_self(), \ 438 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 439 } while (0) 440 441 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 442 do { \ 443 assert(Heap_lock->owned_by_self() || \ 444 (SafepointSynchronize::is_at_safepoint() && \ 445 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 446 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 447 "should be at a safepoint")); \ 448 } while (0) 449 450 #define assert_heap_locked_and_not_at_safepoint() \ 451 do { \ 452 assert(Heap_lock->owned_by_self() && \ 453 !SafepointSynchronize::is_at_safepoint(), \ 454 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 455 "should not be at a safepoint")); \ 456 } while (0) 457 458 #define assert_heap_not_locked() \ 459 do { \ 460 assert(!Heap_lock->owned_by_self(), \ 461 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 462 } while (0) 463 464 #define assert_heap_not_locked_and_not_at_safepoint() \ 465 do { \ 466 assert(!Heap_lock->owned_by_self() && \ 467 !SafepointSynchronize::is_at_safepoint(), \ 468 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 469 "should not be at a safepoint")); \ 470 } while (0) 471 472 #define assert_at_safepoint(_should_be_vm_thread_) \ 473 do { \ 474 assert(SafepointSynchronize::is_at_safepoint() && \ 475 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 476 heap_locking_asserts_err_msg("should be at a safepoint")); \ 477 } while (0) 478 479 #define assert_not_at_safepoint() \ 480 do { \ 481 assert(!SafepointSynchronize::is_at_safepoint(), \ 482 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 483 } while (0) 484 485 protected: 486 487 // The young region list. 488 YoungList* _young_list; 489 490 // The current policy object for the collector. 491 G1CollectorPolicy* _g1_policy; 492 493 // This is the second level of trying to allocate a new region. If 494 // new_region() didn't find a region on the free_list, this call will 495 // check whether there's anything available on the 496 // secondary_free_list and/or wait for more regions to appear on 497 // that list, if _free_regions_coming is set. 498 HeapRegion* new_region_try_secondary_free_list(bool is_old); 499 500 // Try to allocate a single non-humongous HeapRegion sufficient for 501 // an allocation of the given word_size. If do_expand is true, 502 // attempt to expand the heap if necessary to satisfy the allocation 503 // request. If the region is to be used as an old region or for a 504 // humongous object, set is_old to true. If not, to false. 505 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 506 507 // Attempt to satisfy a humongous allocation request of the given 508 // size by finding a contiguous set of free regions of num_regions 509 // length and remove them from the master free list. Return the 510 // index of the first region or G1_NULL_HRS_INDEX if the search 511 // was unsuccessful. 512 uint humongous_obj_allocate_find_first(uint num_regions, 513 size_t word_size); 514 515 // Initialize a contiguous set of free regions of length num_regions 516 // and starting at index first so that they appear as a single 517 // humongous region. 518 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 519 uint num_regions, 520 size_t word_size); 521 522 // Attempt to allocate a humongous object of the given size. Return 523 // NULL if unsuccessful. 524 HeapWord* humongous_obj_allocate(size_t word_size); 525 526 // The following two methods, allocate_new_tlab() and 527 // mem_allocate(), are the two main entry points from the runtime 528 // into the G1's allocation routines. They have the following 529 // assumptions: 530 // 531 // * They should both be called outside safepoints. 532 // 533 // * They should both be called without holding the Heap_lock. 534 // 535 // * All allocation requests for new TLABs should go to 536 // allocate_new_tlab(). 537 // 538 // * All non-TLAB allocation requests should go to mem_allocate(). 539 // 540 // * If either call cannot satisfy the allocation request using the 541 // current allocating region, they will try to get a new one. If 542 // this fails, they will attempt to do an evacuation pause and 543 // retry the allocation. 544 // 545 // * If all allocation attempts fail, even after trying to schedule 546 // an evacuation pause, allocate_new_tlab() will return NULL, 547 // whereas mem_allocate() will attempt a heap expansion and/or 548 // schedule a Full GC. 549 // 550 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 551 // should never be called with word_size being humongous. All 552 // humongous allocation requests should go to mem_allocate() which 553 // will satisfy them with a special path. 554 555 virtual HeapWord* allocate_new_tlab(size_t word_size); 556 557 virtual HeapWord* mem_allocate(size_t word_size, 558 bool* gc_overhead_limit_was_exceeded); 559 560 // The following three methods take a gc_count_before_ret 561 // parameter which is used to return the GC count if the method 562 // returns NULL. Given that we are required to read the GC count 563 // while holding the Heap_lock, and these paths will take the 564 // Heap_lock at some point, it's easier to get them to read the GC 565 // count while holding the Heap_lock before they return NULL instead 566 // of the caller (namely: mem_allocate()) having to also take the 567 // Heap_lock just to read the GC count. 568 569 // First-level mutator allocation attempt: try to allocate out of 570 // the mutator alloc region without taking the Heap_lock. This 571 // should only be used for non-humongous allocations. 572 inline HeapWord* attempt_allocation(size_t word_size, 573 unsigned int* gc_count_before_ret, 574 int* gclocker_retry_count_ret); 575 576 // Second-level mutator allocation attempt: take the Heap_lock and 577 // retry the allocation attempt, potentially scheduling a GC 578 // pause. This should only be used for non-humongous allocations. 579 HeapWord* attempt_allocation_slow(size_t word_size, 580 unsigned int* gc_count_before_ret, 581 int* gclocker_retry_count_ret); 582 583 // Takes the Heap_lock and attempts a humongous allocation. It can 584 // potentially schedule a GC pause. 585 HeapWord* attempt_allocation_humongous(size_t word_size, 586 unsigned int* gc_count_before_ret, 587 int* gclocker_retry_count_ret); 588 589 // Allocation attempt that should be called during safepoints (e.g., 590 // at the end of a successful GC). expect_null_mutator_alloc_region 591 // specifies whether the mutator alloc region is expected to be NULL 592 // or not. 593 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 594 bool expect_null_mutator_alloc_region); 595 596 // It dirties the cards that cover the block so that so that the post 597 // write barrier never queues anything when updating objects on this 598 // block. It is assumed (and in fact we assert) that the block 599 // belongs to a young region. 600 inline void dirty_young_block(HeapWord* start, size_t word_size); 601 602 // Allocate blocks during garbage collection. Will ensure an 603 // allocation region, either by picking one or expanding the 604 // heap, and then allocate a block of the given size. The block 605 // may not be a humongous - it must fit into a single heap region. 606 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 607 608 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 609 HeapRegion* alloc_region, 610 bool par, 611 size_t word_size); 612 613 // Ensure that no further allocations can happen in "r", bearing in mind 614 // that parallel threads might be attempting allocations. 615 void par_allocate_remaining_space(HeapRegion* r); 616 617 // Allocation attempt during GC for a survivor object / PLAB. 618 inline HeapWord* survivor_attempt_allocation(size_t word_size); 619 620 // Allocation attempt during GC for an old object / PLAB. 621 inline HeapWord* old_attempt_allocation(size_t word_size); 622 623 // These methods are the "callbacks" from the G1AllocRegion class. 624 625 // For mutator alloc regions. 626 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 627 void retire_mutator_alloc_region(HeapRegion* alloc_region, 628 size_t allocated_bytes); 629 630 // For GC alloc regions. 631 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 632 GCAllocPurpose ap); 633 void retire_gc_alloc_region(HeapRegion* alloc_region, 634 size_t allocated_bytes, GCAllocPurpose ap); 635 636 // - if explicit_gc is true, the GC is for a System.gc() or a heap 637 // inspection request and should collect the entire heap 638 // - if clear_all_soft_refs is true, all soft references should be 639 // cleared during the GC 640 // - if explicit_gc is false, word_size describes the allocation that 641 // the GC should attempt (at least) to satisfy 642 // - it returns false if it is unable to do the collection due to the 643 // GC locker being active, true otherwise 644 bool do_collection(bool explicit_gc, 645 bool clear_all_soft_refs, 646 size_t word_size); 647 648 // Callback from VM_G1CollectFull operation. 649 // Perform a full collection. 650 virtual void do_full_collection(bool clear_all_soft_refs); 651 652 // Resize the heap if necessary after a full collection. If this is 653 // after a collect-for allocation, "word_size" is the allocation size, 654 // and will be considered part of the used portion of the heap. 655 void resize_if_necessary_after_full_collection(size_t word_size); 656 657 // Callback from VM_G1CollectForAllocation operation. 658 // This function does everything necessary/possible to satisfy a 659 // failed allocation request (including collection, expansion, etc.) 660 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 661 662 // Attempting to expand the heap sufficiently 663 // to support an allocation of the given "word_size". If 664 // successful, perform the allocation and return the address of the 665 // allocated block, or else "NULL". 666 HeapWord* expand_and_allocate(size_t word_size); 667 668 // Process any reference objects discovered during 669 // an incremental evacuation pause. 670 void process_discovered_references(uint no_of_gc_workers); 671 672 // Enqueue any remaining discovered references 673 // after processing. 674 void enqueue_discovered_references(uint no_of_gc_workers); 675 676 public: 677 678 G1MonitoringSupport* g1mm() { 679 assert(_g1mm != NULL, "should have been initialized"); 680 return _g1mm; 681 } 682 683 // Expand the garbage-first heap by at least the given size (in bytes!). 684 // Returns true if the heap was expanded by the requested amount; 685 // false otherwise. 686 // (Rounds up to a HeapRegion boundary.) 687 bool expand(size_t expand_bytes); 688 689 // Do anything common to GC's. 690 virtual void gc_prologue(bool full); 691 virtual void gc_epilogue(bool full); 692 693 // We register a region with the fast "in collection set" test. We 694 // simply set to true the array slot corresponding to this region. 695 void register_region_with_in_cset_fast_test(HeapRegion* r) { 696 _in_cset_fast_test.set_by_index(r->hrs_index(), true); 697 } 698 699 // This is a fast test on whether a reference points into the 700 // collection set or not. Assume that the reference 701 // points into the heap. 702 inline bool in_cset_fast_test(oop obj); 703 704 void clear_cset_fast_test() { 705 _in_cset_fast_test.clear(); 706 } 707 708 // This is called at the start of either a concurrent cycle or a Full 709 // GC to update the number of old marking cycles started. 710 void increment_old_marking_cycles_started(); 711 712 // This is called at the end of either a concurrent cycle or a Full 713 // GC to update the number of old marking cycles completed. Those two 714 // can happen in a nested fashion, i.e., we start a concurrent 715 // cycle, a Full GC happens half-way through it which ends first, 716 // and then the cycle notices that a Full GC happened and ends 717 // too. The concurrent parameter is a boolean to help us do a bit 718 // tighter consistency checking in the method. If concurrent is 719 // false, the caller is the inner caller in the nesting (i.e., the 720 // Full GC). If concurrent is true, the caller is the outer caller 721 // in this nesting (i.e., the concurrent cycle). Further nesting is 722 // not currently supported. The end of this call also notifies 723 // the FullGCCount_lock in case a Java thread is waiting for a full 724 // GC to happen (e.g., it called System.gc() with 725 // +ExplicitGCInvokesConcurrent). 726 void increment_old_marking_cycles_completed(bool concurrent); 727 728 unsigned int old_marking_cycles_completed() { 729 return _old_marking_cycles_completed; 730 } 731 732 void register_concurrent_cycle_start(const Ticks& start_time); 733 void register_concurrent_cycle_end(); 734 void trace_heap_after_concurrent_cycle(); 735 736 G1YCType yc_type(); 737 738 G1HRPrinter* hr_printer() { return &_hr_printer; } 739 740 // Frees a non-humongous region by initializing its contents and 741 // adding it to the free list that's passed as a parameter (this is 742 // usually a local list which will be appended to the master free 743 // list later). The used bytes of freed regions are accumulated in 744 // pre_used. If par is true, the region's RSet will not be freed 745 // up. The assumption is that this will be done later. 746 // The locked parameter indicates if the caller has already taken 747 // care of proper synchronization. This may allow some optimizations. 748 void free_region(HeapRegion* hr, 749 FreeRegionList* free_list, 750 bool par, 751 bool locked = false); 752 753 // Frees a humongous region by collapsing it into individual regions 754 // and calling free_region() for each of them. The freed regions 755 // will be added to the free list that's passed as a parameter (this 756 // is usually a local list which will be appended to the master free 757 // list later). The used bytes of freed regions are accumulated in 758 // pre_used. If par is true, the region's RSet will not be freed 759 // up. The assumption is that this will be done later. 760 void free_humongous_region(HeapRegion* hr, 761 FreeRegionList* free_list, 762 bool par); 763 protected: 764 765 // Shrink the garbage-first heap by at most the given size (in bytes!). 766 // (Rounds down to a HeapRegion boundary.) 767 virtual void shrink(size_t expand_bytes); 768 void shrink_helper(size_t expand_bytes); 769 770 #if TASKQUEUE_STATS 771 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 772 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 773 void reset_taskqueue_stats(); 774 #endif // TASKQUEUE_STATS 775 776 // Schedule the VM operation that will do an evacuation pause to 777 // satisfy an allocation request of word_size. *succeeded will 778 // return whether the VM operation was successful (it did do an 779 // evacuation pause) or not (another thread beat us to it or the GC 780 // locker was active). Given that we should not be holding the 781 // Heap_lock when we enter this method, we will pass the 782 // gc_count_before (i.e., total_collections()) as a parameter since 783 // it has to be read while holding the Heap_lock. Currently, both 784 // methods that call do_collection_pause() release the Heap_lock 785 // before the call, so it's easy to read gc_count_before just before. 786 HeapWord* do_collection_pause(size_t word_size, 787 unsigned int gc_count_before, 788 bool* succeeded, 789 GCCause::Cause gc_cause); 790 791 // The guts of the incremental collection pause, executed by the vm 792 // thread. It returns false if it is unable to do the collection due 793 // to the GC locker being active, true otherwise 794 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 795 796 // Actually do the work of evacuating the collection set. 797 void evacuate_collection_set(EvacuationInfo& evacuation_info); 798 799 // The g1 remembered set of the heap. 800 G1RemSet* _g1_rem_set; 801 802 // A set of cards that cover the objects for which the Rsets should be updated 803 // concurrently after the collection. 804 DirtyCardQueueSet _dirty_card_queue_set; 805 806 // The closure used to refine a single card. 807 RefineCardTableEntryClosure* _refine_cte_cl; 808 809 // A function to check the consistency of dirty card logs. 810 void check_ct_logs_at_safepoint(); 811 812 // A DirtyCardQueueSet that is used to hold cards that contain 813 // references into the current collection set. This is used to 814 // update the remembered sets of the regions in the collection 815 // set in the event of an evacuation failure. 816 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 817 818 // After a collection pause, make the regions in the CS into free 819 // regions. 820 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 821 822 // Abandon the current collection set without recording policy 823 // statistics or updating free lists. 824 void abandon_collection_set(HeapRegion* cs_head); 825 826 // Applies "scan_non_heap_roots" to roots outside the heap, 827 // "scan_rs" to roots inside the heap (having done "set_region" to 828 // indicate the region in which the root resides), 829 // and does "scan_metadata" If "scan_rs" is 830 // NULL, then this step is skipped. The "worker_i" 831 // param is for use with parallel roots processing, and should be 832 // the "i" of the calling parallel worker thread's work(i) function. 833 // In the sequential case this param will be ignored. 834 void g1_process_roots(OopClosure* scan_non_heap_roots, 835 OopClosure* scan_non_heap_weak_roots, 836 OopsInHeapRegionClosure* scan_rs, 837 CLDClosure* scan_strong_clds, 838 CLDClosure* scan_weak_clds, 839 CodeBlobClosure* scan_strong_code, 840 uint worker_i); 841 842 // Notifies all the necessary spaces that the committed space has 843 // been updated (either expanded or shrunk). It should be called 844 // after _g1_storage is updated. 845 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 846 847 // The concurrent marker (and the thread it runs in.) 848 ConcurrentMark* _cm; 849 ConcurrentMarkThread* _cmThread; 850 bool _mark_in_progress; 851 852 // The concurrent refiner. 853 ConcurrentG1Refine* _cg1r; 854 855 // The parallel task queues 856 RefToScanQueueSet *_task_queues; 857 858 // True iff a evacuation has failed in the current collection. 859 bool _evacuation_failed; 860 861 EvacuationFailedInfo* _evacuation_failed_info_array; 862 863 // Failed evacuations cause some logical from-space objects to have 864 // forwarding pointers to themselves. Reset them. 865 void remove_self_forwarding_pointers(); 866 867 // Together, these store an object with a preserved mark, and its mark value. 868 Stack<oop, mtGC> _objs_with_preserved_marks; 869 Stack<markOop, mtGC> _preserved_marks_of_objs; 870 871 // Preserve the mark of "obj", if necessary, in preparation for its mark 872 // word being overwritten with a self-forwarding-pointer. 873 void preserve_mark_if_necessary(oop obj, markOop m); 874 875 // The stack of evac-failure objects left to be scanned. 876 GrowableArray<oop>* _evac_failure_scan_stack; 877 // The closure to apply to evac-failure objects. 878 879 OopsInHeapRegionClosure* _evac_failure_closure; 880 // Set the field above. 881 void 882 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 883 _evac_failure_closure = evac_failure_closure; 884 } 885 886 // Push "obj" on the scan stack. 887 void push_on_evac_failure_scan_stack(oop obj); 888 // Process scan stack entries until the stack is empty. 889 void drain_evac_failure_scan_stack(); 890 // True iff an invocation of "drain_scan_stack" is in progress; to 891 // prevent unnecessary recursion. 892 bool _drain_in_progress; 893 894 // Do any necessary initialization for evacuation-failure handling. 895 // "cl" is the closure that will be used to process evac-failure 896 // objects. 897 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 898 // Do any necessary cleanup for evacuation-failure handling data 899 // structures. 900 void finalize_for_evac_failure(); 901 902 // An attempt to evacuate "obj" has failed; take necessary steps. 903 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 904 void handle_evacuation_failure_common(oop obj, markOop m); 905 906 #ifndef PRODUCT 907 // Support for forcing evacuation failures. Analogous to 908 // PromotionFailureALot for the other collectors. 909 910 // Records whether G1EvacuationFailureALot should be in effect 911 // for the current GC 912 bool _evacuation_failure_alot_for_current_gc; 913 914 // Used to record the GC number for interval checking when 915 // determining whether G1EvaucationFailureALot is in effect 916 // for the current GC. 917 size_t _evacuation_failure_alot_gc_number; 918 919 // Count of the number of evacuations between failures. 920 volatile size_t _evacuation_failure_alot_count; 921 922 // Set whether G1EvacuationFailureALot should be in effect 923 // for the current GC (based upon the type of GC and which 924 // command line flags are set); 925 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 926 bool during_initial_mark, 927 bool during_marking); 928 929 inline void set_evacuation_failure_alot_for_current_gc(); 930 931 // Return true if it's time to cause an evacuation failure. 932 inline bool evacuation_should_fail(); 933 934 // Reset the G1EvacuationFailureALot counters. Should be called at 935 // the end of an evacuation pause in which an evacuation failure occurred. 936 inline void reset_evacuation_should_fail(); 937 #endif // !PRODUCT 938 939 // ("Weak") Reference processing support. 940 // 941 // G1 has 2 instances of the reference processor class. One 942 // (_ref_processor_cm) handles reference object discovery 943 // and subsequent processing during concurrent marking cycles. 944 // 945 // The other (_ref_processor_stw) handles reference object 946 // discovery and processing during full GCs and incremental 947 // evacuation pauses. 948 // 949 // During an incremental pause, reference discovery will be 950 // temporarily disabled for _ref_processor_cm and will be 951 // enabled for _ref_processor_stw. At the end of the evacuation 952 // pause references discovered by _ref_processor_stw will be 953 // processed and discovery will be disabled. The previous 954 // setting for reference object discovery for _ref_processor_cm 955 // will be re-instated. 956 // 957 // At the start of marking: 958 // * Discovery by the CM ref processor is verified to be inactive 959 // and it's discovered lists are empty. 960 // * Discovery by the CM ref processor is then enabled. 961 // 962 // At the end of marking: 963 // * Any references on the CM ref processor's discovered 964 // lists are processed (possibly MT). 965 // 966 // At the start of full GC we: 967 // * Disable discovery by the CM ref processor and 968 // empty CM ref processor's discovered lists 969 // (without processing any entries). 970 // * Verify that the STW ref processor is inactive and it's 971 // discovered lists are empty. 972 // * Temporarily set STW ref processor discovery as single threaded. 973 // * Temporarily clear the STW ref processor's _is_alive_non_header 974 // field. 975 // * Finally enable discovery by the STW ref processor. 976 // 977 // The STW ref processor is used to record any discovered 978 // references during the full GC. 979 // 980 // At the end of a full GC we: 981 // * Enqueue any reference objects discovered by the STW ref processor 982 // that have non-live referents. This has the side-effect of 983 // making the STW ref processor inactive by disabling discovery. 984 // * Verify that the CM ref processor is still inactive 985 // and no references have been placed on it's discovered 986 // lists (also checked as a precondition during initial marking). 987 988 // The (stw) reference processor... 989 ReferenceProcessor* _ref_processor_stw; 990 991 STWGCTimer* _gc_timer_stw; 992 ConcurrentGCTimer* _gc_timer_cm; 993 994 G1OldTracer* _gc_tracer_cm; 995 G1NewTracer* _gc_tracer_stw; 996 997 // During reference object discovery, the _is_alive_non_header 998 // closure (if non-null) is applied to the referent object to 999 // determine whether the referent is live. If so then the 1000 // reference object does not need to be 'discovered' and can 1001 // be treated as a regular oop. This has the benefit of reducing 1002 // the number of 'discovered' reference objects that need to 1003 // be processed. 1004 // 1005 // Instance of the is_alive closure for embedding into the 1006 // STW reference processor as the _is_alive_non_header field. 1007 // Supplying a value for the _is_alive_non_header field is 1008 // optional but doing so prevents unnecessary additions to 1009 // the discovered lists during reference discovery. 1010 G1STWIsAliveClosure _is_alive_closure_stw; 1011 1012 // The (concurrent marking) reference processor... 1013 ReferenceProcessor* _ref_processor_cm; 1014 1015 // Instance of the concurrent mark is_alive closure for embedding 1016 // into the Concurrent Marking reference processor as the 1017 // _is_alive_non_header field. Supplying a value for the 1018 // _is_alive_non_header field is optional but doing so prevents 1019 // unnecessary additions to the discovered lists during reference 1020 // discovery. 1021 G1CMIsAliveClosure _is_alive_closure_cm; 1022 1023 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1024 HeapRegion** _worker_cset_start_region; 1025 1026 // Time stamp to validate the regions recorded in the cache 1027 // used by G1CollectedHeap::start_cset_region_for_worker(). 1028 // The heap region entry for a given worker is valid iff 1029 // the associated time stamp value matches the current value 1030 // of G1CollectedHeap::_gc_time_stamp. 1031 unsigned int* _worker_cset_start_region_time_stamp; 1032 1033 enum G1H_process_roots_tasks { 1034 G1H_PS_filter_satb_buffers, 1035 G1H_PS_refProcessor_oops_do, 1036 // Leave this one last. 1037 G1H_PS_NumElements 1038 }; 1039 1040 SubTasksDone* _process_strong_tasks; 1041 1042 volatile bool _free_regions_coming; 1043 1044 public: 1045 1046 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1047 1048 void set_refine_cte_cl_concurrency(bool concurrent); 1049 1050 RefToScanQueue *task_queue(int i) const; 1051 1052 // A set of cards where updates happened during the GC 1053 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1054 1055 // A DirtyCardQueueSet that is used to hold cards that contain 1056 // references into the current collection set. This is used to 1057 // update the remembered sets of the regions in the collection 1058 // set in the event of an evacuation failure. 1059 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1060 { return _into_cset_dirty_card_queue_set; } 1061 1062 // Create a G1CollectedHeap with the specified policy. 1063 // Must call the initialize method afterwards. 1064 // May not return if something goes wrong. 1065 G1CollectedHeap(G1CollectorPolicy* policy); 1066 1067 // Initialize the G1CollectedHeap to have the initial and 1068 // maximum sizes and remembered and barrier sets 1069 // specified by the policy object. 1070 jint initialize(); 1071 1072 virtual void stop(); 1073 1074 // Return the (conservative) maximum heap alignment for any G1 heap 1075 static size_t conservative_max_heap_alignment(); 1076 1077 // Initialize weak reference processing. 1078 virtual void ref_processing_init(); 1079 1080 void set_par_threads(uint t) { 1081 SharedHeap::set_par_threads(t); 1082 // Done in SharedHeap but oddly there are 1083 // two _process_strong_tasks's in a G1CollectedHeap 1084 // so do it here too. 1085 _process_strong_tasks->set_n_threads(t); 1086 } 1087 1088 // Set _n_par_threads according to a policy TBD. 1089 void set_par_threads(); 1090 1091 void set_n_termination(int t) { 1092 _process_strong_tasks->set_n_threads(t); 1093 } 1094 1095 virtual CollectedHeap::Name kind() const { 1096 return CollectedHeap::G1CollectedHeap; 1097 } 1098 1099 // The current policy object for the collector. 1100 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1101 1102 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1103 1104 // Adaptive size policy. No such thing for g1. 1105 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1106 1107 // The rem set and barrier set. 1108 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1109 1110 unsigned get_gc_time_stamp() { 1111 return _gc_time_stamp; 1112 } 1113 1114 inline void reset_gc_time_stamp(); 1115 1116 void check_gc_time_stamps() PRODUCT_RETURN; 1117 1118 inline void increment_gc_time_stamp(); 1119 1120 // Reset the given region's GC timestamp. If it's starts humongous, 1121 // also reset the GC timestamp of its corresponding 1122 // continues humongous regions too. 1123 void reset_gc_time_stamps(HeapRegion* hr); 1124 1125 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1126 DirtyCardQueue* into_cset_dcq, 1127 bool concurrent, uint worker_i); 1128 1129 // The shared block offset table array. 1130 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1131 1132 // Reference Processing accessors 1133 1134 // The STW reference processor.... 1135 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1136 1137 // The Concurrent Marking reference processor... 1138 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1139 1140 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1141 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1142 1143 virtual size_t capacity() const; 1144 virtual size_t used() const; 1145 // This should be called when we're not holding the heap lock. The 1146 // result might be a bit inaccurate. 1147 size_t used_unlocked() const; 1148 size_t recalculate_used() const; 1149 1150 // These virtual functions do the actual allocation. 1151 // Some heaps may offer a contiguous region for shared non-blocking 1152 // allocation, via inlined code (by exporting the address of the top and 1153 // end fields defining the extent of the contiguous allocation region.) 1154 // But G1CollectedHeap doesn't yet support this. 1155 1156 virtual bool is_maximal_no_gc() const { 1157 return _g1_storage.uncommitted_size() == 0; 1158 } 1159 1160 // The total number of regions in the heap. 1161 uint n_regions() { return _hrs.length(); } 1162 1163 // The max number of regions in the heap. 1164 uint max_regions() { return _hrs.max_length(); } 1165 1166 // The number of regions that are completely free. 1167 uint free_regions() { return _free_list.length(); } 1168 1169 // The number of regions that are not completely free. 1170 uint used_regions() { return n_regions() - free_regions(); } 1171 1172 // The number of regions available for "regular" expansion. 1173 uint expansion_regions() { return _expansion_regions; } 1174 1175 // Factory method for HeapRegion instances. It will return NULL if 1176 // the allocation fails. 1177 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1178 1179 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1180 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1181 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1182 void verify_dirty_young_regions() PRODUCT_RETURN; 1183 1184 #ifndef PRODUCT 1185 // Make sure that the given bitmap has no marked objects in the 1186 // range [from,limit). If it does, print an error message and return 1187 // false. Otherwise, just return true. bitmap_name should be "prev" 1188 // or "next". 1189 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1190 HeapWord* from, HeapWord* limit); 1191 1192 // Verify that the prev / next bitmap range [tams,end) for the given 1193 // region has no marks. Return true if all is well, false if errors 1194 // are detected. 1195 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1196 #endif // PRODUCT 1197 1198 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1199 // the given region do not have any spurious marks. If errors are 1200 // detected, print appropriate error messages and crash. 1201 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1202 1203 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1204 // have any spurious marks. If errors are detected, print 1205 // appropriate error messages and crash. 1206 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1207 1208 // verify_region_sets() performs verification over the region 1209 // lists. It will be compiled in the product code to be used when 1210 // necessary (i.e., during heap verification). 1211 void verify_region_sets(); 1212 1213 // verify_region_sets_optional() is planted in the code for 1214 // list verification in non-product builds (and it can be enabled in 1215 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1216 #if HEAP_REGION_SET_FORCE_VERIFY 1217 void verify_region_sets_optional() { 1218 verify_region_sets(); 1219 } 1220 #else // HEAP_REGION_SET_FORCE_VERIFY 1221 void verify_region_sets_optional() { } 1222 #endif // HEAP_REGION_SET_FORCE_VERIFY 1223 1224 #ifdef ASSERT 1225 bool is_on_master_free_list(HeapRegion* hr) { 1226 return hr->containing_set() == &_free_list; 1227 } 1228 #endif // ASSERT 1229 1230 // Wrapper for the region list operations that can be called from 1231 // methods outside this class. 1232 1233 void secondary_free_list_add(FreeRegionList* list) { 1234 _secondary_free_list.add_ordered(list); 1235 } 1236 1237 void append_secondary_free_list() { 1238 _free_list.add_ordered(&_secondary_free_list); 1239 } 1240 1241 void append_secondary_free_list_if_not_empty_with_lock() { 1242 // If the secondary free list looks empty there's no reason to 1243 // take the lock and then try to append it. 1244 if (!_secondary_free_list.is_empty()) { 1245 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1246 append_secondary_free_list(); 1247 } 1248 } 1249 1250 inline void old_set_remove(HeapRegion* hr); 1251 1252 size_t non_young_capacity_bytes() { 1253 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1254 } 1255 1256 void set_free_regions_coming(); 1257 void reset_free_regions_coming(); 1258 bool free_regions_coming() { return _free_regions_coming; } 1259 void wait_while_free_regions_coming(); 1260 1261 // Determine whether the given region is one that we are using as an 1262 // old GC alloc region. 1263 bool is_old_gc_alloc_region(HeapRegion* hr) { 1264 return hr == _retained_old_gc_alloc_region; 1265 } 1266 1267 // Perform a collection of the heap; intended for use in implementing 1268 // "System.gc". This probably implies as full a collection as the 1269 // "CollectedHeap" supports. 1270 virtual void collect(GCCause::Cause cause); 1271 1272 // The same as above but assume that the caller holds the Heap_lock. 1273 void collect_locked(GCCause::Cause cause); 1274 1275 // True iff an evacuation has failed in the most-recent collection. 1276 bool evacuation_failed() { return _evacuation_failed; } 1277 1278 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1279 void prepend_to_freelist(FreeRegionList* list); 1280 void decrement_summary_bytes(size_t bytes); 1281 1282 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1283 virtual bool is_in(const void* p) const; 1284 1285 // Return "TRUE" iff the given object address is within the collection 1286 // set. 1287 inline bool obj_in_cs(oop obj); 1288 1289 // Return "TRUE" iff the given object address is in the reserved 1290 // region of g1. 1291 bool is_in_g1_reserved(const void* p) const { 1292 return _g1_reserved.contains(p); 1293 } 1294 1295 // Returns a MemRegion that corresponds to the space that has been 1296 // reserved for the heap 1297 MemRegion g1_reserved() { 1298 return _g1_reserved; 1299 } 1300 1301 // Returns a MemRegion that corresponds to the space that has been 1302 // committed in the heap 1303 MemRegion g1_committed() { 1304 return _g1_committed; 1305 } 1306 1307 virtual bool is_in_closed_subset(const void* p) const; 1308 1309 G1SATBCardTableModRefBS* g1_barrier_set() { 1310 return (G1SATBCardTableModRefBS*) barrier_set(); 1311 } 1312 1313 // This resets the card table to all zeros. It is used after 1314 // a collection pause which used the card table to claim cards. 1315 void cleanUpCardTable(); 1316 1317 // Iteration functions. 1318 1319 // Iterate over all the ref-containing fields of all objects, calling 1320 // "cl.do_oop" on each. 1321 virtual void oop_iterate(ExtendedOopClosure* cl); 1322 1323 // Same as above, restricted to a memory region. 1324 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1325 1326 // Iterate over all objects, calling "cl.do_object" on each. 1327 virtual void object_iterate(ObjectClosure* cl); 1328 1329 virtual void safe_object_iterate(ObjectClosure* cl) { 1330 object_iterate(cl); 1331 } 1332 1333 // Iterate over all spaces in use in the heap, in ascending address order. 1334 virtual void space_iterate(SpaceClosure* cl); 1335 1336 // Iterate over heap regions, in address order, terminating the 1337 // iteration early if the "doHeapRegion" method returns "true". 1338 void heap_region_iterate(HeapRegionClosure* blk) const; 1339 1340 // Return the region with the given index. It assumes the index is valid. 1341 inline HeapRegion* region_at(uint index) const; 1342 1343 // Divide the heap region sequence into "chunks" of some size (the number 1344 // of regions divided by the number of parallel threads times some 1345 // overpartition factor, currently 4). Assumes that this will be called 1346 // in parallel by ParallelGCThreads worker threads with distinct worker 1347 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1348 // calls will use the same "claim_value", and that that claim value is 1349 // different from the claim_value of any heap region before the start of 1350 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1351 // attempting to claim the first region in each chunk, and, if 1352 // successful, applying the closure to each region in the chunk (and 1353 // setting the claim value of the second and subsequent regions of the 1354 // chunk.) For now requires that "doHeapRegion" always returns "false", 1355 // i.e., that a closure never attempt to abort a traversal. 1356 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1357 uint worker, 1358 uint no_of_par_workers, 1359 jint claim_value); 1360 1361 // It resets all the region claim values to the default. 1362 void reset_heap_region_claim_values(); 1363 1364 // Resets the claim values of regions in the current 1365 // collection set to the default. 1366 void reset_cset_heap_region_claim_values(); 1367 1368 #ifdef ASSERT 1369 bool check_heap_region_claim_values(jint claim_value); 1370 1371 // Same as the routine above but only checks regions in the 1372 // current collection set. 1373 bool check_cset_heap_region_claim_values(jint claim_value); 1374 #endif // ASSERT 1375 1376 // Clear the cached cset start regions and (more importantly) 1377 // the time stamps. Called when we reset the GC time stamp. 1378 void clear_cset_start_regions(); 1379 1380 // Given the id of a worker, obtain or calculate a suitable 1381 // starting region for iterating over the current collection set. 1382 HeapRegion* start_cset_region_for_worker(uint worker_i); 1383 1384 // This is a convenience method that is used by the 1385 // HeapRegionIterator classes to calculate the starting region for 1386 // each worker so that they do not all start from the same region. 1387 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1388 1389 // Iterate over the regions (if any) in the current collection set. 1390 void collection_set_iterate(HeapRegionClosure* blk); 1391 1392 // As above but starting from region r 1393 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1394 1395 // Returns the first (lowest address) compactible space in the heap. 1396 virtual CompactibleSpace* first_compactible_space(); 1397 1398 // A CollectedHeap will contain some number of spaces. This finds the 1399 // space containing a given address, or else returns NULL. 1400 virtual Space* space_containing(const void* addr) const; 1401 1402 // Returns the HeapRegion that contains addr. addr must not be NULL. 1403 template <class T> 1404 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1405 1406 // Returns the HeapRegion that contains addr. addr must not be NULL. 1407 // If addr is within a humongous continues region, it returns its humongous start region. 1408 template <class T> 1409 inline HeapRegion* heap_region_containing(const T addr) const; 1410 1411 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1412 // each address in the (reserved) heap is a member of exactly 1413 // one block. The defining characteristic of a block is that it is 1414 // possible to find its size, and thus to progress forward to the next 1415 // block. (Blocks may be of different sizes.) Thus, blocks may 1416 // represent Java objects, or they might be free blocks in a 1417 // free-list-based heap (or subheap), as long as the two kinds are 1418 // distinguishable and the size of each is determinable. 1419 1420 // Returns the address of the start of the "block" that contains the 1421 // address "addr". We say "blocks" instead of "object" since some heaps 1422 // may not pack objects densely; a chunk may either be an object or a 1423 // non-object. 1424 virtual HeapWord* block_start(const void* addr) const; 1425 1426 // Requires "addr" to be the start of a chunk, and returns its size. 1427 // "addr + size" is required to be the start of a new chunk, or the end 1428 // of the active area of the heap. 1429 virtual size_t block_size(const HeapWord* addr) const; 1430 1431 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1432 // the block is an object. 1433 virtual bool block_is_obj(const HeapWord* addr) const; 1434 1435 // Does this heap support heap inspection? (+PrintClassHistogram) 1436 virtual bool supports_heap_inspection() const { return true; } 1437 1438 // Section on thread-local allocation buffers (TLABs) 1439 // See CollectedHeap for semantics. 1440 1441 bool supports_tlab_allocation() const; 1442 size_t tlab_capacity(Thread* ignored) const; 1443 size_t tlab_used(Thread* ignored) const; 1444 size_t max_tlab_size() const; 1445 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1446 1447 // Can a compiler initialize a new object without store barriers? 1448 // This permission only extends from the creation of a new object 1449 // via a TLAB up to the first subsequent safepoint. If such permission 1450 // is granted for this heap type, the compiler promises to call 1451 // defer_store_barrier() below on any slow path allocation of 1452 // a new object for which such initializing store barriers will 1453 // have been elided. G1, like CMS, allows this, but should be 1454 // ready to provide a compensating write barrier as necessary 1455 // if that storage came out of a non-young region. The efficiency 1456 // of this implementation depends crucially on being able to 1457 // answer very efficiently in constant time whether a piece of 1458 // storage in the heap comes from a young region or not. 1459 // See ReduceInitialCardMarks. 1460 virtual bool can_elide_tlab_store_barriers() const { 1461 return true; 1462 } 1463 1464 virtual bool card_mark_must_follow_store() const { 1465 return true; 1466 } 1467 1468 inline bool is_in_young(const oop obj); 1469 1470 #ifdef ASSERT 1471 virtual bool is_in_partial_collection(const void* p); 1472 #endif 1473 1474 virtual bool is_scavengable(const void* addr); 1475 1476 // We don't need barriers for initializing stores to objects 1477 // in the young gen: for the SATB pre-barrier, there is no 1478 // pre-value that needs to be remembered; for the remembered-set 1479 // update logging post-barrier, we don't maintain remembered set 1480 // information for young gen objects. 1481 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1482 1483 // Returns "true" iff the given word_size is "very large". 1484 static bool isHumongous(size_t word_size) { 1485 // Note this has to be strictly greater-than as the TLABs 1486 // are capped at the humongous threshold and we want to 1487 // ensure that we don't try to allocate a TLAB as 1488 // humongous and that we don't allocate a humongous 1489 // object in a TLAB. 1490 return word_size > _humongous_object_threshold_in_words; 1491 } 1492 1493 // Update mod union table with the set of dirty cards. 1494 void updateModUnion(); 1495 1496 // Set the mod union bits corresponding to the given memRegion. Note 1497 // that this is always a safe operation, since it doesn't clear any 1498 // bits. 1499 void markModUnionRange(MemRegion mr); 1500 1501 // Records the fact that a marking phase is no longer in progress. 1502 void set_marking_complete() { 1503 _mark_in_progress = false; 1504 } 1505 void set_marking_started() { 1506 _mark_in_progress = true; 1507 } 1508 bool mark_in_progress() { 1509 return _mark_in_progress; 1510 } 1511 1512 // Print the maximum heap capacity. 1513 virtual size_t max_capacity() const; 1514 1515 virtual jlong millis_since_last_gc(); 1516 1517 1518 // Convenience function to be used in situations where the heap type can be 1519 // asserted to be this type. 1520 static G1CollectedHeap* heap(); 1521 1522 void set_region_short_lived_locked(HeapRegion* hr); 1523 // add appropriate methods for any other surv rate groups 1524 1525 YoungList* young_list() const { return _young_list; } 1526 1527 // debugging 1528 bool check_young_list_well_formed() { 1529 return _young_list->check_list_well_formed(); 1530 } 1531 1532 bool check_young_list_empty(bool check_heap, 1533 bool check_sample = true); 1534 1535 // *** Stuff related to concurrent marking. It's not clear to me that so 1536 // many of these need to be public. 1537 1538 // The functions below are helper functions that a subclass of 1539 // "CollectedHeap" can use in the implementation of its virtual 1540 // functions. 1541 // This performs a concurrent marking of the live objects in a 1542 // bitmap off to the side. 1543 void doConcurrentMark(); 1544 1545 bool isMarkedPrev(oop obj) const; 1546 bool isMarkedNext(oop obj) const; 1547 1548 // Determine if an object is dead, given the object and also 1549 // the region to which the object belongs. An object is dead 1550 // iff a) it was not allocated since the last mark and b) it 1551 // is not marked. 1552 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1553 return 1554 !hr->obj_allocated_since_prev_marking(obj) && 1555 !isMarkedPrev(obj); 1556 } 1557 1558 // This function returns true when an object has been 1559 // around since the previous marking and hasn't yet 1560 // been marked during this marking. 1561 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1562 return 1563 !hr->obj_allocated_since_next_marking(obj) && 1564 !isMarkedNext(obj); 1565 } 1566 1567 // Determine if an object is dead, given only the object itself. 1568 // This will find the region to which the object belongs and 1569 // then call the region version of the same function. 1570 1571 // Added if it is NULL it isn't dead. 1572 1573 inline bool is_obj_dead(const oop obj) const; 1574 1575 inline bool is_obj_ill(const oop obj) const; 1576 1577 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1578 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1579 bool is_marked(oop obj, VerifyOption vo); 1580 const char* top_at_mark_start_str(VerifyOption vo); 1581 1582 ConcurrentMark* concurrent_mark() const { return _cm; } 1583 1584 // Refinement 1585 1586 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1587 1588 // The dirty cards region list is used to record a subset of regions 1589 // whose cards need clearing. The list if populated during the 1590 // remembered set scanning and drained during the card table 1591 // cleanup. Although the methods are reentrant, population/draining 1592 // phases must not overlap. For synchronization purposes the last 1593 // element on the list points to itself. 1594 HeapRegion* _dirty_cards_region_list; 1595 void push_dirty_cards_region(HeapRegion* hr); 1596 HeapRegion* pop_dirty_cards_region(); 1597 1598 // Optimized nmethod scanning support routines 1599 1600 // Register the given nmethod with the G1 heap. 1601 virtual void register_nmethod(nmethod* nm); 1602 1603 // Unregister the given nmethod from the G1 heap. 1604 virtual void unregister_nmethod(nmethod* nm); 1605 1606 // Migrate the nmethods in the code root lists of the regions 1607 // in the collection set to regions in to-space. In the event 1608 // of an evacuation failure, nmethods that reference objects 1609 // that were not successfully evacuated are not migrated. 1610 void migrate_strong_code_roots(); 1611 1612 // Free up superfluous code root memory. 1613 void purge_code_root_memory(); 1614 1615 // Rebuild the strong code root lists for each region 1616 // after a full GC. 1617 void rebuild_strong_code_roots(); 1618 1619 // Delete entries for dead interned string and clean up unreferenced symbols 1620 // in symbol table, possibly in parallel. 1621 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1622 1623 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1624 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1625 1626 // Redirty logged cards in the refinement queue. 1627 void redirty_logged_cards(); 1628 // Verification 1629 1630 // The following is just to alert the verification code 1631 // that a full collection has occurred and that the 1632 // remembered sets are no longer up to date. 1633 bool _full_collection; 1634 void set_full_collection() { _full_collection = true;} 1635 void clear_full_collection() {_full_collection = false;} 1636 bool full_collection() {return _full_collection;} 1637 1638 // Perform any cleanup actions necessary before allowing a verification. 1639 virtual void prepare_for_verify(); 1640 1641 // Perform verification. 1642 1643 // vo == UsePrevMarking -> use "prev" marking information, 1644 // vo == UseNextMarking -> use "next" marking information 1645 // vo == UseMarkWord -> use the mark word in the object header 1646 // 1647 // NOTE: Only the "prev" marking information is guaranteed to be 1648 // consistent most of the time, so most calls to this should use 1649 // vo == UsePrevMarking. 1650 // Currently, there is only one case where this is called with 1651 // vo == UseNextMarking, which is to verify the "next" marking 1652 // information at the end of remark. 1653 // Currently there is only one place where this is called with 1654 // vo == UseMarkWord, which is to verify the marking during a 1655 // full GC. 1656 void verify(bool silent, VerifyOption vo); 1657 1658 // Override; it uses the "prev" marking information 1659 virtual void verify(bool silent); 1660 1661 // The methods below are here for convenience and dispatch the 1662 // appropriate method depending on value of the given VerifyOption 1663 // parameter. The values for that parameter, and their meanings, 1664 // are the same as those above. 1665 1666 bool is_obj_dead_cond(const oop obj, 1667 const HeapRegion* hr, 1668 const VerifyOption vo) const; 1669 1670 bool is_obj_dead_cond(const oop obj, 1671 const VerifyOption vo) const; 1672 1673 // Printing 1674 1675 virtual void print_on(outputStream* st) const; 1676 virtual void print_extended_on(outputStream* st) const; 1677 virtual void print_on_error(outputStream* st) const; 1678 1679 virtual void print_gc_threads_on(outputStream* st) const; 1680 virtual void gc_threads_do(ThreadClosure* tc) const; 1681 1682 // Override 1683 void print_tracing_info() const; 1684 1685 // The following two methods are helpful for debugging RSet issues. 1686 void print_cset_rsets() PRODUCT_RETURN; 1687 void print_all_rsets() PRODUCT_RETURN; 1688 1689 public: 1690 size_t pending_card_num(); 1691 size_t cards_scanned(); 1692 1693 protected: 1694 size_t _max_heap_capacity; 1695 }; 1696 1697 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1698 private: 1699 bool _retired; 1700 1701 public: 1702 G1ParGCAllocBuffer(size_t gclab_word_size); 1703 virtual ~G1ParGCAllocBuffer() { 1704 guarantee(_retired, "Allocation buffer has not been retired"); 1705 } 1706 1707 virtual void set_buf(HeapWord* buf) { 1708 ParGCAllocBuffer::set_buf(buf); 1709 _retired = false; 1710 } 1711 1712 virtual void retire(bool end_of_gc, bool retain) { 1713 if (_retired) { 1714 return; 1715 } 1716 ParGCAllocBuffer::retire(end_of_gc, retain); 1717 _retired = true; 1718 } 1719 }; 1720 1721 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP