1 /* 2 * Copyright (c) 2001, 2015, 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_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/concurrentMark.hpp" 29 #include "gc/g1/evacuationInfo.hpp" 30 #include "gc/g1/g1AllocationContext.hpp" 31 #include "gc/g1/g1Allocator.hpp" 32 #include "gc/g1/g1BiasedArray.hpp" 33 #include "gc/g1/g1CollectorState.hpp" 34 #include "gc/g1/g1HRPrinter.hpp" 35 #include "gc/g1/g1InCSetState.hpp" 36 #include "gc/g1/g1MonitoringSupport.hpp" 37 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 38 #include "gc/g1/g1YCTypes.hpp" 39 #include "gc/g1/hSpaceCounters.hpp" 40 #include "gc/g1/heapRegionManager.hpp" 41 #include "gc/g1/heapRegionSet.hpp" 42 #include "gc/shared/barrierSet.hpp" 43 #include "gc/shared/collectedHeap.hpp" 44 #include "memory/memRegion.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 G1ParScanThreadState; 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 class FlexibleWorkGang; 79 80 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 81 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 82 83 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 84 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 85 86 class YoungList : public CHeapObj<mtGC> { 87 private: 88 G1CollectedHeap* _g1h; 89 90 HeapRegion* _head; 91 92 HeapRegion* _survivor_head; 93 HeapRegion* _survivor_tail; 94 95 HeapRegion* _curr; 96 97 uint _length; 98 uint _survivor_length; 99 100 size_t _last_sampled_rs_lengths; 101 size_t _sampled_rs_lengths; 102 103 void empty_list(HeapRegion* list); 104 105 public: 106 YoungList(G1CollectedHeap* g1h); 107 108 void push_region(HeapRegion* hr); 109 void add_survivor_region(HeapRegion* hr); 110 111 void empty_list(); 112 bool is_empty() { return _length == 0; } 113 uint length() { return _length; } 114 uint eden_length() { return length() - survivor_length(); } 115 uint survivor_length() { return _survivor_length; } 116 117 // Currently we do not keep track of the used byte sum for the 118 // young list and the survivors and it'd be quite a lot of work to 119 // do so. When we'll eventually replace the young list with 120 // instances of HeapRegionLinkedList we'll get that for free. So, 121 // we'll report the more accurate information then. 122 size_t eden_used_bytes() { 123 assert(length() >= survivor_length(), "invariant"); 124 return (size_t) eden_length() * HeapRegion::GrainBytes; 125 } 126 size_t survivor_used_bytes() { 127 return (size_t) survivor_length() * HeapRegion::GrainBytes; 128 } 129 130 void rs_length_sampling_init(); 131 bool rs_length_sampling_more(); 132 void rs_length_sampling_next(); 133 134 void reset_sampled_info() { 135 _last_sampled_rs_lengths = 0; 136 } 137 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 138 139 // for development purposes 140 void reset_auxilary_lists(); 141 void clear() { _head = NULL; _length = 0; } 142 143 void clear_survivors() { 144 _survivor_head = NULL; 145 _survivor_tail = NULL; 146 _survivor_length = 0; 147 } 148 149 HeapRegion* first_region() { return _head; } 150 HeapRegion* first_survivor_region() { return _survivor_head; } 151 HeapRegion* last_survivor_region() { return _survivor_tail; } 152 153 // debugging 154 bool check_list_well_formed(); 155 bool check_list_empty(bool check_sample = true); 156 void print(); 157 }; 158 159 // The G1 STW is alive closure. 160 // An instance is embedded into the G1CH and used as the 161 // (optional) _is_alive_non_header closure in the STW 162 // reference processor. It is also extensively used during 163 // reference processing during STW evacuation pauses. 164 class G1STWIsAliveClosure: public BoolObjectClosure { 165 G1CollectedHeap* _g1; 166 public: 167 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 168 bool do_object_b(oop p); 169 }; 170 171 class RefineCardTableEntryClosure; 172 173 class G1RegionMappingChangedListener : public G1MappingChangedListener { 174 private: 175 void reset_from_card_cache(uint start_idx, size_t num_regions); 176 public: 177 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 178 }; 179 180 class G1CollectedHeap : public CollectedHeap { 181 friend class VM_CollectForMetadataAllocation; 182 friend class VM_G1CollectForAllocation; 183 friend class VM_G1CollectFull; 184 friend class VM_G1IncCollectionPause; 185 friend class VMStructs; 186 friend class MutatorAllocRegion; 187 friend class SurvivorGCAllocRegion; 188 friend class OldGCAllocRegion; 189 friend class G1Allocator; 190 friend class G1ArchiveAllocator; 191 192 // Closures used in implementation. 193 friend class G1ParScanThreadState; 194 friend class G1ParTask; 195 friend class G1PLABAllocator; 196 friend class G1PrepareCompactClosure; 197 198 // Other related classes. 199 friend class HeapRegionClaimer; 200 201 // Testing classes. 202 friend class G1CheckCSetFastTableClosure; 203 204 private: 205 FlexibleWorkGang* _workers; 206 207 static size_t _humongous_object_threshold_in_words; 208 209 // The secondary free list which contains regions that have been 210 // freed up during the cleanup process. This will be appended to 211 // the master free list when appropriate. 212 FreeRegionList _secondary_free_list; 213 214 // It keeps track of the old regions. 215 HeapRegionSet _old_set; 216 217 // It keeps track of the humongous regions. 218 HeapRegionSet _humongous_set; 219 220 void eagerly_reclaim_humongous_regions(); 221 222 // The number of regions we could create by expansion. 223 uint _expansion_regions; 224 225 // The block offset table for the G1 heap. 226 G1BlockOffsetSharedArray* _bot_shared; 227 228 // Tears down the region sets / lists so that they are empty and the 229 // regions on the heap do not belong to a region set / list. The 230 // only exception is the humongous set which we leave unaltered. If 231 // free_list_only is true, it will only tear down the master free 232 // list. It is called before a Full GC (free_list_only == false) or 233 // before heap shrinking (free_list_only == true). 234 void tear_down_region_sets(bool free_list_only); 235 236 // Rebuilds the region sets / lists so that they are repopulated to 237 // reflect the contents of the heap. The only exception is the 238 // humongous set which was not torn down in the first place. If 239 // free_list_only is true, it will only rebuild the master free 240 // list. It is called after a Full GC (free_list_only == false) or 241 // after heap shrinking (free_list_only == true). 242 void rebuild_region_sets(bool free_list_only); 243 244 // Callback for region mapping changed events. 245 G1RegionMappingChangedListener _listener; 246 247 // The sequence of all heap regions in the heap. 248 HeapRegionManager _hrm; 249 250 // Handles non-humongous allocations in the G1CollectedHeap. 251 G1Allocator* _allocator; 252 253 // Outside of GC pauses, the number of bytes used in all regions other 254 // than the current allocation region(s). 255 size_t _summary_bytes_used; 256 257 void increase_used(size_t bytes); 258 void decrease_used(size_t bytes); 259 260 void set_used(size_t bytes); 261 262 // Class that handles archive allocation ranges. 263 G1ArchiveAllocator* _archive_allocator; 264 265 // Statistics for each allocation context 266 AllocationContextStats _allocation_context_stats; 267 268 // PLAB sizing policy for survivors. 269 PLABStats _survivor_plab_stats; 270 271 // PLAB sizing policy for tenured objects. 272 PLABStats _old_plab_stats; 273 274 // It specifies whether we should attempt to expand the heap after a 275 // region allocation failure. If heap expansion fails we set this to 276 // false so that we don't re-attempt the heap expansion (it's likely 277 // that subsequent expansion attempts will also fail if one fails). 278 // Currently, it is only consulted during GC and it's reset at the 279 // start of each GC. 280 bool _expand_heap_after_alloc_failure; 281 282 // Helper for monitoring and management support. 283 G1MonitoringSupport* _g1mm; 284 285 // Records whether the region at the given index is (still) a 286 // candidate for eager reclaim. Only valid for humongous start 287 // regions; other regions have unspecified values. Humongous start 288 // regions are initialized at start of collection pause, with 289 // candidates removed from the set as they are found reachable from 290 // roots or the young generation. 291 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 292 protected: 293 bool default_value() const { return false; } 294 public: 295 void clear() { G1BiasedMappedArray<bool>::clear(); } 296 void set_candidate(uint region, bool value) { 297 set_by_index(region, value); 298 } 299 bool is_candidate(uint region) { 300 return get_by_index(region); 301 } 302 }; 303 304 HumongousReclaimCandidates _humongous_reclaim_candidates; 305 // Stores whether during humongous object registration we found candidate regions. 306 // If not, we can skip a few steps. 307 bool _has_humongous_reclaim_candidates; 308 309 volatile unsigned _gc_time_stamp; 310 311 size_t* _surviving_young_words; 312 313 G1HRPrinter _hr_printer; 314 315 void setup_surviving_young_words(); 316 void update_surviving_young_words(size_t* surv_young_words); 317 void cleanup_surviving_young_words(); 318 319 // It decides whether an explicit GC should start a concurrent cycle 320 // instead of doing a STW GC. Currently, a concurrent cycle is 321 // explicitly started if: 322 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 323 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 324 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 325 // (d) cause == _g1_humongous_allocation 326 bool should_do_concurrent_full_gc(GCCause::Cause cause); 327 328 // indicates whether we are in young or mixed GC mode 329 G1CollectorState _collector_state; 330 331 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 332 // concurrent cycles) we have started. 333 volatile uint _old_marking_cycles_started; 334 335 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 336 // concurrent cycles) we have completed. 337 volatile uint _old_marking_cycles_completed; 338 339 bool _heap_summary_sent; 340 341 // This is a non-product method that is helpful for testing. It is 342 // called at the end of a GC and artificially expands the heap by 343 // allocating a number of dead regions. This way we can induce very 344 // frequent marking cycles and stress the cleanup / concurrent 345 // cleanup code more (as all the regions that will be allocated by 346 // this method will be found dead by the marking cycle). 347 void allocate_dummy_regions() PRODUCT_RETURN; 348 349 // Clear RSets after a compaction. It also resets the GC time stamps. 350 void clear_rsets_post_compaction(); 351 352 // If the HR printer is active, dump the state of the regions in the 353 // heap after a compaction. 354 void print_hrm_post_compaction(); 355 356 // Create a memory mapper for auxiliary data structures of the given size and 357 // translation factor. 358 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 359 size_t size, 360 size_t translation_factor); 361 362 double verify(bool guard, const char* msg); 363 void verify_before_gc(); 364 void verify_after_gc(); 365 366 void log_gc_header(); 367 void log_gc_footer(double pause_time_sec); 368 369 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 370 371 // These are macros so that, if the assert fires, we get the correct 372 // line number, file, etc. 373 374 #define heap_locking_asserts_err_msg(_extra_message_) \ 375 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 376 (_extra_message_), \ 377 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 378 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 379 BOOL_TO_STR(Thread::current()->is_VM_thread())) 380 381 #define assert_heap_locked() \ 382 do { \ 383 assert(Heap_lock->owned_by_self(), \ 384 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 385 } while (0) 386 387 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 388 do { \ 389 assert(Heap_lock->owned_by_self() || \ 390 (SafepointSynchronize::is_at_safepoint() && \ 391 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 392 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 393 "should be at a safepoint")); \ 394 } while (0) 395 396 #define assert_heap_locked_and_not_at_safepoint() \ 397 do { \ 398 assert(Heap_lock->owned_by_self() && \ 399 !SafepointSynchronize::is_at_safepoint(), \ 400 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 401 "should not be at a safepoint")); \ 402 } while (0) 403 404 #define assert_heap_not_locked() \ 405 do { \ 406 assert(!Heap_lock->owned_by_self(), \ 407 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 408 } while (0) 409 410 #define assert_heap_not_locked_and_not_at_safepoint() \ 411 do { \ 412 assert(!Heap_lock->owned_by_self() && \ 413 !SafepointSynchronize::is_at_safepoint(), \ 414 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 415 "should not be at a safepoint")); \ 416 } while (0) 417 418 #define assert_at_safepoint(_should_be_vm_thread_) \ 419 do { \ 420 assert(SafepointSynchronize::is_at_safepoint() && \ 421 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 422 heap_locking_asserts_err_msg("should be at a safepoint")); \ 423 } while (0) 424 425 #define assert_not_at_safepoint() \ 426 do { \ 427 assert(!SafepointSynchronize::is_at_safepoint(), \ 428 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 429 } while (0) 430 431 protected: 432 433 // The young region list. 434 YoungList* _young_list; 435 436 // The current policy object for the collector. 437 G1CollectorPolicy* _g1_policy; 438 439 // This is the second level of trying to allocate a new region. If 440 // new_region() didn't find a region on the free_list, this call will 441 // check whether there's anything available on the 442 // secondary_free_list and/or wait for more regions to appear on 443 // that list, if _free_regions_coming is set. 444 HeapRegion* new_region_try_secondary_free_list(bool is_old); 445 446 // Try to allocate a single non-humongous HeapRegion sufficient for 447 // an allocation of the given word_size. If do_expand is true, 448 // attempt to expand the heap if necessary to satisfy the allocation 449 // request. If the region is to be used as an old region or for a 450 // humongous object, set is_old to true. If not, to false. 451 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 452 453 // Initialize a contiguous set of free regions of length num_regions 454 // and starting at index first so that they appear as a single 455 // humongous region. 456 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 457 uint num_regions, 458 size_t word_size, 459 AllocationContext_t context); 460 461 // Attempt to allocate a humongous object of the given size. Return 462 // NULL if unsuccessful. 463 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 464 465 // The following two methods, allocate_new_tlab() and 466 // mem_allocate(), are the two main entry points from the runtime 467 // into the G1's allocation routines. They have the following 468 // assumptions: 469 // 470 // * They should both be called outside safepoints. 471 // 472 // * They should both be called without holding the Heap_lock. 473 // 474 // * All allocation requests for new TLABs should go to 475 // allocate_new_tlab(). 476 // 477 // * All non-TLAB allocation requests should go to mem_allocate(). 478 // 479 // * If either call cannot satisfy the allocation request using the 480 // current allocating region, they will try to get a new one. If 481 // this fails, they will attempt to do an evacuation pause and 482 // retry the allocation. 483 // 484 // * If all allocation attempts fail, even after trying to schedule 485 // an evacuation pause, allocate_new_tlab() will return NULL, 486 // whereas mem_allocate() will attempt a heap expansion and/or 487 // schedule a Full GC. 488 // 489 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 490 // should never be called with word_size being humongous. All 491 // humongous allocation requests should go to mem_allocate() which 492 // will satisfy them with a special path. 493 494 virtual HeapWord* allocate_new_tlab(size_t word_size); 495 496 virtual HeapWord* mem_allocate(size_t word_size, 497 bool* gc_overhead_limit_was_exceeded); 498 499 // The following three methods take a gc_count_before_ret 500 // parameter which is used to return the GC count if the method 501 // returns NULL. Given that we are required to read the GC count 502 // while holding the Heap_lock, and these paths will take the 503 // Heap_lock at some point, it's easier to get them to read the GC 504 // count while holding the Heap_lock before they return NULL instead 505 // of the caller (namely: mem_allocate()) having to also take the 506 // Heap_lock just to read the GC count. 507 508 // First-level mutator allocation attempt: try to allocate out of 509 // the mutator alloc region without taking the Heap_lock. This 510 // should only be used for non-humongous allocations. 511 inline HeapWord* attempt_allocation(size_t word_size, 512 uint* gc_count_before_ret, 513 uint* gclocker_retry_count_ret); 514 515 // Second-level mutator allocation attempt: take the Heap_lock and 516 // retry the allocation attempt, potentially scheduling a GC 517 // pause. This should only be used for non-humongous allocations. 518 HeapWord* attempt_allocation_slow(size_t word_size, 519 AllocationContext_t context, 520 uint* gc_count_before_ret, 521 uint* gclocker_retry_count_ret); 522 523 // Takes the Heap_lock and attempts a humongous allocation. It can 524 // potentially schedule a GC pause. 525 HeapWord* attempt_allocation_humongous(size_t word_size, 526 uint* gc_count_before_ret, 527 uint* gclocker_retry_count_ret); 528 529 // Allocation attempt that should be called during safepoints (e.g., 530 // at the end of a successful GC). expect_null_mutator_alloc_region 531 // specifies whether the mutator alloc region is expected to be NULL 532 // or not. 533 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 534 AllocationContext_t context, 535 bool expect_null_mutator_alloc_region); 536 537 // It dirties the cards that cover the block so that so that the post 538 // write barrier never queues anything when updating objects on this 539 // block. It is assumed (and in fact we assert) that the block 540 // belongs to a young region. 541 inline void dirty_young_block(HeapWord* start, size_t word_size); 542 543 // These methods are the "callbacks" from the G1AllocRegion class. 544 545 // For mutator alloc regions. 546 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 547 void retire_mutator_alloc_region(HeapRegion* alloc_region, 548 size_t allocated_bytes); 549 550 // For GC alloc regions. 551 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 552 InCSetState dest); 553 void retire_gc_alloc_region(HeapRegion* alloc_region, 554 size_t allocated_bytes, InCSetState dest); 555 556 // Allocate the highest free region in the reserved heap. This will commit 557 // regions as necessary. 558 HeapRegion* alloc_highest_free_region(); 559 560 // - if explicit_gc is true, the GC is for a System.gc() or a heap 561 // inspection request and should collect the entire heap 562 // - if clear_all_soft_refs is true, all soft references should be 563 // cleared during the GC 564 // - if explicit_gc is false, word_size describes the allocation that 565 // the GC should attempt (at least) to satisfy 566 // - it returns false if it is unable to do the collection due to the 567 // GC locker being active, true otherwise 568 bool do_collection(bool explicit_gc, 569 bool clear_all_soft_refs, 570 size_t word_size); 571 572 // Callback from VM_G1CollectFull operation. 573 // Perform a full collection. 574 virtual void do_full_collection(bool clear_all_soft_refs); 575 576 // Resize the heap if necessary after a full collection. If this is 577 // after a collect-for allocation, "word_size" is the allocation size, 578 // and will be considered part of the used portion of the heap. 579 void resize_if_necessary_after_full_collection(size_t word_size); 580 581 // Callback from VM_G1CollectForAllocation operation. 582 // This function does everything necessary/possible to satisfy a 583 // failed allocation request (including collection, expansion, etc.) 584 HeapWord* satisfy_failed_allocation(size_t word_size, 585 AllocationContext_t context, 586 bool* succeeded); 587 588 // Attempting to expand the heap sufficiently 589 // to support an allocation of the given "word_size". If 590 // successful, perform the allocation and return the address of the 591 // allocated block, or else "NULL". 592 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 593 594 // Process any reference objects discovered during 595 // an incremental evacuation pause. 596 void process_discovered_references(); 597 598 // Enqueue any remaining discovered references 599 // after processing. 600 void enqueue_discovered_references(); 601 602 public: 603 FlexibleWorkGang* workers() const { return _workers; } 604 605 G1Allocator* allocator() { 606 return _allocator; 607 } 608 609 G1MonitoringSupport* g1mm() { 610 assert(_g1mm != NULL, "should have been initialized"); 611 return _g1mm; 612 } 613 614 // Expand the garbage-first heap by at least the given size (in bytes!). 615 // Returns true if the heap was expanded by the requested amount; 616 // false otherwise. 617 // (Rounds up to a HeapRegion boundary.) 618 bool expand(size_t expand_bytes); 619 620 // Returns the PLAB statistics for a given destination. 621 inline PLABStats* alloc_buffer_stats(InCSetState dest); 622 623 // Determines PLAB size for a given destination. 624 inline size_t desired_plab_sz(InCSetState dest); 625 626 inline AllocationContextStats& allocation_context_stats(); 627 628 // Do anything common to GC's. 629 void gc_prologue(bool full); 630 void gc_epilogue(bool full); 631 632 // Modify the reclaim candidate set and test for presence. 633 // These are only valid for starts_humongous regions. 634 inline void set_humongous_reclaim_candidate(uint region, bool value); 635 inline bool is_humongous_reclaim_candidate(uint region); 636 637 // Remove from the reclaim candidate set. Also remove from the 638 // collection set so that later encounters avoid the slow path. 639 inline void set_humongous_is_live(oop obj); 640 641 // Register the given region to be part of the collection set. 642 inline void register_humongous_region_with_cset(uint index); 643 // Register regions with humongous objects (actually on the start region) in 644 // the in_cset_fast_test table. 645 void register_humongous_regions_with_cset(); 646 // We register a region with the fast "in collection set" test. We 647 // simply set to true the array slot corresponding to this region. 648 void register_young_region_with_cset(HeapRegion* r) { 649 _in_cset_fast_test.set_in_young(r->hrm_index()); 650 } 651 void register_old_region_with_cset(HeapRegion* r) { 652 _in_cset_fast_test.set_in_old(r->hrm_index()); 653 } 654 void clear_in_cset(const HeapRegion* hr) { 655 _in_cset_fast_test.clear(hr); 656 } 657 658 void clear_cset_fast_test() { 659 _in_cset_fast_test.clear(); 660 } 661 662 // This is called at the start of either a concurrent cycle or a Full 663 // GC to update the number of old marking cycles started. 664 void increment_old_marking_cycles_started(); 665 666 // This is called at the end of either a concurrent cycle or a Full 667 // GC to update the number of old marking cycles completed. Those two 668 // can happen in a nested fashion, i.e., we start a concurrent 669 // cycle, a Full GC happens half-way through it which ends first, 670 // and then the cycle notices that a Full GC happened and ends 671 // too. The concurrent parameter is a boolean to help us do a bit 672 // tighter consistency checking in the method. If concurrent is 673 // false, the caller is the inner caller in the nesting (i.e., the 674 // Full GC). If concurrent is true, the caller is the outer caller 675 // in this nesting (i.e., the concurrent cycle). Further nesting is 676 // not currently supported. The end of this call also notifies 677 // the FullGCCount_lock in case a Java thread is waiting for a full 678 // GC to happen (e.g., it called System.gc() with 679 // +ExplicitGCInvokesConcurrent). 680 void increment_old_marking_cycles_completed(bool concurrent); 681 682 uint old_marking_cycles_completed() { 683 return _old_marking_cycles_completed; 684 } 685 686 void register_concurrent_cycle_start(const Ticks& start_time); 687 void register_concurrent_cycle_end(); 688 void trace_heap_after_concurrent_cycle(); 689 690 G1HRPrinter* hr_printer() { return &_hr_printer; } 691 692 // Allocates a new heap region instance. 693 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 694 695 // Frees a non-humongous region by initializing its contents and 696 // adding it to the free list that's passed as a parameter (this is 697 // usually a local list which will be appended to the master free 698 // list later). The used bytes of freed regions are accumulated in 699 // pre_used. If par is true, the region's RSet will not be freed 700 // up. The assumption is that this will be done later. 701 // The locked parameter indicates if the caller has already taken 702 // care of proper synchronization. This may allow some optimizations. 703 void free_region(HeapRegion* hr, 704 FreeRegionList* free_list, 705 bool par, 706 bool locked = false); 707 708 // Frees a humongous region by collapsing it into individual regions 709 // and calling free_region() for each of them. The freed regions 710 // will be added to the free list that's passed as a parameter (this 711 // is usually a local list which will be appended to the master free 712 // list later). The used bytes of freed regions are accumulated in 713 // pre_used. If par is true, the region's RSet will not be freed 714 // up. The assumption is that this will be done later. 715 void free_humongous_region(HeapRegion* hr, 716 FreeRegionList* free_list, 717 bool par); 718 719 // Facility for allocating in 'archive' regions in high heap memory and 720 // recording the allocated ranges. These should all be called from the 721 // VM thread at safepoints, without the heap lock held. They can be used 722 // to create and archive a set of heap regions which can be mapped at the 723 // same fixed addresses in a subsequent JVM invocation. 724 void begin_archive_alloc_range(); 725 726 // Check if the requested size would be too large for an archive allocation. 727 bool is_archive_alloc_too_large(size_t word_size); 728 729 // Allocate memory of the requested size from the archive region. This will 730 // return NULL if the size is too large or if no memory is available. It 731 // does not trigger a garbage collection. 732 HeapWord* archive_mem_allocate(size_t word_size); 733 734 // Optionally aligns the end address and returns the allocated ranges in 735 // an array of MemRegions in order of ascending addresses. 736 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 737 size_t end_alignment_in_bytes = 0); 738 739 // Facility for allocating a fixed range within the heap and marking 740 // the containing regions as 'archive'. For use at JVM init time, when the 741 // caller may mmap archived heap data at the specified range(s). 742 // Verify that the MemRegions specified in the argument array are within the 743 // reserved heap. 744 bool check_archive_addresses(MemRegion* range, size_t count); 745 746 // Commit the appropriate G1 regions containing the specified MemRegions 747 // and mark them as 'archive' regions. The regions in the array must be 748 // non-overlapping and in order of ascending address. 749 bool alloc_archive_regions(MemRegion* range, size_t count); 750 751 // Insert any required filler objects in the G1 regions around the specified 752 // ranges to make the regions parseable. This must be called after 753 // alloc_archive_regions, and after class loading has occurred. 754 void fill_archive_regions(MemRegion* range, size_t count); 755 756 protected: 757 758 // Shrink the garbage-first heap by at most the given size (in bytes!). 759 // (Rounds down to a HeapRegion boundary.) 760 virtual void shrink(size_t expand_bytes); 761 void shrink_helper(size_t expand_bytes); 762 763 #if TASKQUEUE_STATS 764 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 765 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 766 void reset_taskqueue_stats(); 767 #endif // TASKQUEUE_STATS 768 769 // Schedule the VM operation that will do an evacuation pause to 770 // satisfy an allocation request of word_size. *succeeded will 771 // return whether the VM operation was successful (it did do an 772 // evacuation pause) or not (another thread beat us to it or the GC 773 // locker was active). Given that we should not be holding the 774 // Heap_lock when we enter this method, we will pass the 775 // gc_count_before (i.e., total_collections()) as a parameter since 776 // it has to be read while holding the Heap_lock. Currently, both 777 // methods that call do_collection_pause() release the Heap_lock 778 // before the call, so it's easy to read gc_count_before just before. 779 HeapWord* do_collection_pause(size_t word_size, 780 uint gc_count_before, 781 bool* succeeded, 782 GCCause::Cause gc_cause); 783 784 void wait_for_root_region_scanning(); 785 786 // The guts of the incremental collection pause, executed by the vm 787 // thread. It returns false if it is unable to do the collection due 788 // to the GC locker being active, true otherwise 789 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 790 791 // Actually do the work of evacuating the collection set. 792 void evacuate_collection_set(EvacuationInfo& evacuation_info); 793 794 // The g1 remembered set of the heap. 795 G1RemSet* _g1_rem_set; 796 797 // A set of cards that cover the objects for which the Rsets should be updated 798 // concurrently after the collection. 799 DirtyCardQueueSet _dirty_card_queue_set; 800 801 // The closure used to refine a single card. 802 RefineCardTableEntryClosure* _refine_cte_cl; 803 804 // A DirtyCardQueueSet that is used to hold cards that contain 805 // references into the current collection set. This is used to 806 // update the remembered sets of the regions in the collection 807 // set in the event of an evacuation failure. 808 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 809 810 // After a collection pause, make the regions in the CS into free 811 // regions. 812 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 813 814 // Abandon the current collection set without recording policy 815 // statistics or updating free lists. 816 void abandon_collection_set(HeapRegion* cs_head); 817 818 // The concurrent marker (and the thread it runs in.) 819 ConcurrentMark* _cm; 820 ConcurrentMarkThread* _cmThread; 821 822 // The concurrent refiner. 823 ConcurrentG1Refine* _cg1r; 824 825 // The parallel task queues 826 RefToScanQueueSet *_task_queues; 827 828 // True iff a evacuation has failed in the current collection. 829 bool _evacuation_failed; 830 831 EvacuationFailedInfo* _evacuation_failed_info_array; 832 833 // Failed evacuations cause some logical from-space objects to have 834 // forwarding pointers to themselves. Reset them. 835 void remove_self_forwarding_pointers(); 836 837 struct OopAndMarkOop { 838 private: 839 oop _o; 840 markOop _m; 841 public: 842 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { 843 } 844 845 void set_mark() { 846 _o->set_mark(_m); 847 } 848 }; 849 850 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack; 851 // Stores marks with the corresponding oop that we need to preserve during evacuation 852 // failure. 853 OopAndMarkOopStack* _preserved_objs; 854 855 // Preserve the mark of "obj", if necessary, in preparation for its mark 856 // word being overwritten with a self-forwarding-pointer. 857 void preserve_mark_during_evac_failure(uint queue, oop obj, markOop m); 858 859 #ifndef PRODUCT 860 // Support for forcing evacuation failures. Analogous to 861 // PromotionFailureALot for the other collectors. 862 863 // Records whether G1EvacuationFailureALot should be in effect 864 // for the current GC 865 bool _evacuation_failure_alot_for_current_gc; 866 867 // Used to record the GC number for interval checking when 868 // determining whether G1EvaucationFailureALot is in effect 869 // for the current GC. 870 size_t _evacuation_failure_alot_gc_number; 871 872 // Count of the number of evacuations between failures. 873 volatile size_t _evacuation_failure_alot_count; 874 875 // Set whether G1EvacuationFailureALot should be in effect 876 // for the current GC (based upon the type of GC and which 877 // command line flags are set); 878 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 879 bool during_initial_mark, 880 bool during_marking); 881 882 inline void set_evacuation_failure_alot_for_current_gc(); 883 884 // Return true if it's time to cause an evacuation failure. 885 inline bool evacuation_should_fail(); 886 887 // Reset the G1EvacuationFailureALot counters. Should be called at 888 // the end of an evacuation pause in which an evacuation failure occurred. 889 inline void reset_evacuation_should_fail(); 890 #endif // !PRODUCT 891 892 // ("Weak") Reference processing support. 893 // 894 // G1 has 2 instances of the reference processor class. One 895 // (_ref_processor_cm) handles reference object discovery 896 // and subsequent processing during concurrent marking cycles. 897 // 898 // The other (_ref_processor_stw) handles reference object 899 // discovery and processing during full GCs and incremental 900 // evacuation pauses. 901 // 902 // During an incremental pause, reference discovery will be 903 // temporarily disabled for _ref_processor_cm and will be 904 // enabled for _ref_processor_stw. At the end of the evacuation 905 // pause references discovered by _ref_processor_stw will be 906 // processed and discovery will be disabled. The previous 907 // setting for reference object discovery for _ref_processor_cm 908 // will be re-instated. 909 // 910 // At the start of marking: 911 // * Discovery by the CM ref processor is verified to be inactive 912 // and it's discovered lists are empty. 913 // * Discovery by the CM ref processor is then enabled. 914 // 915 // At the end of marking: 916 // * Any references on the CM ref processor's discovered 917 // lists are processed (possibly MT). 918 // 919 // At the start of full GC we: 920 // * Disable discovery by the CM ref processor and 921 // empty CM ref processor's discovered lists 922 // (without processing any entries). 923 // * Verify that the STW ref processor is inactive and it's 924 // discovered lists are empty. 925 // * Temporarily set STW ref processor discovery as single threaded. 926 // * Temporarily clear the STW ref processor's _is_alive_non_header 927 // field. 928 // * Finally enable discovery by the STW ref processor. 929 // 930 // The STW ref processor is used to record any discovered 931 // references during the full GC. 932 // 933 // At the end of a full GC we: 934 // * Enqueue any reference objects discovered by the STW ref processor 935 // that have non-live referents. This has the side-effect of 936 // making the STW ref processor inactive by disabling discovery. 937 // * Verify that the CM ref processor is still inactive 938 // and no references have been placed on it's discovered 939 // lists (also checked as a precondition during initial marking). 940 941 // The (stw) reference processor... 942 ReferenceProcessor* _ref_processor_stw; 943 944 STWGCTimer* _gc_timer_stw; 945 ConcurrentGCTimer* _gc_timer_cm; 946 947 G1OldTracer* _gc_tracer_cm; 948 G1NewTracer* _gc_tracer_stw; 949 950 // During reference object discovery, the _is_alive_non_header 951 // closure (if non-null) is applied to the referent object to 952 // determine whether the referent is live. If so then the 953 // reference object does not need to be 'discovered' and can 954 // be treated as a regular oop. This has the benefit of reducing 955 // the number of 'discovered' reference objects that need to 956 // be processed. 957 // 958 // Instance of the is_alive closure for embedding into the 959 // STW reference processor as the _is_alive_non_header field. 960 // Supplying a value for the _is_alive_non_header field is 961 // optional but doing so prevents unnecessary additions to 962 // the discovered lists during reference discovery. 963 G1STWIsAliveClosure _is_alive_closure_stw; 964 965 // The (concurrent marking) reference processor... 966 ReferenceProcessor* _ref_processor_cm; 967 968 // Instance of the concurrent mark is_alive closure for embedding 969 // into the Concurrent Marking reference processor as the 970 // _is_alive_non_header field. Supplying a value for the 971 // _is_alive_non_header field is optional but doing so prevents 972 // unnecessary additions to the discovered lists during reference 973 // discovery. 974 G1CMIsAliveClosure _is_alive_closure_cm; 975 976 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 977 HeapRegion** _worker_cset_start_region; 978 979 // Time stamp to validate the regions recorded in the cache 980 // used by G1CollectedHeap::start_cset_region_for_worker(). 981 // The heap region entry for a given worker is valid iff 982 // the associated time stamp value matches the current value 983 // of G1CollectedHeap::_gc_time_stamp. 984 uint* _worker_cset_start_region_time_stamp; 985 986 volatile bool _free_regions_coming; 987 988 public: 989 990 void set_refine_cte_cl_concurrency(bool concurrent); 991 992 RefToScanQueue *task_queue(uint i) const; 993 994 uint num_task_queues() const; 995 996 // A set of cards where updates happened during the GC 997 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 998 999 // A DirtyCardQueueSet that is used to hold cards that contain 1000 // references into the current collection set. This is used to 1001 // update the remembered sets of the regions in the collection 1002 // set in the event of an evacuation failure. 1003 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1004 { return _into_cset_dirty_card_queue_set; } 1005 1006 // Create a G1CollectedHeap with the specified policy. 1007 // Must call the initialize method afterwards. 1008 // May not return if something goes wrong. 1009 G1CollectedHeap(G1CollectorPolicy* policy); 1010 1011 // Initialize the G1CollectedHeap to have the initial and 1012 // maximum sizes and remembered and barrier sets 1013 // specified by the policy object. 1014 jint initialize(); 1015 1016 virtual void stop(); 1017 1018 // Return the (conservative) maximum heap alignment for any G1 heap 1019 static size_t conservative_max_heap_alignment(); 1020 1021 // Does operations required after initialization has been done. 1022 void post_initialize(); 1023 1024 // Initialize weak reference processing. 1025 void ref_processing_init(); 1026 1027 virtual Name kind() const { 1028 return CollectedHeap::G1CollectedHeap; 1029 } 1030 1031 G1CollectorState* collector_state() { return &_collector_state; } 1032 1033 // The current policy object for the collector. 1034 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1035 1036 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1037 1038 // Adaptive size policy. No such thing for g1. 1039 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1040 1041 // The rem set and barrier set. 1042 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1043 1044 unsigned get_gc_time_stamp() { 1045 return _gc_time_stamp; 1046 } 1047 1048 inline void reset_gc_time_stamp(); 1049 1050 void check_gc_time_stamps() PRODUCT_RETURN; 1051 1052 inline void increment_gc_time_stamp(); 1053 1054 // Reset the given region's GC timestamp. If it's starts humongous, 1055 // also reset the GC timestamp of its corresponding 1056 // continues humongous regions too. 1057 void reset_gc_time_stamps(HeapRegion* hr); 1058 1059 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1060 DirtyCardQueue* into_cset_dcq, 1061 bool concurrent, uint worker_i); 1062 1063 // The shared block offset table array. 1064 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1065 1066 // Reference Processing accessors 1067 1068 // The STW reference processor.... 1069 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1070 1071 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1072 1073 // The Concurrent Marking reference processor... 1074 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1075 1076 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1077 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1078 1079 virtual size_t capacity() const; 1080 virtual size_t used() const; 1081 // This should be called when we're not holding the heap lock. The 1082 // result might be a bit inaccurate. 1083 size_t used_unlocked() const; 1084 size_t recalculate_used() const; 1085 1086 // These virtual functions do the actual allocation. 1087 // Some heaps may offer a contiguous region for shared non-blocking 1088 // allocation, via inlined code (by exporting the address of the top and 1089 // end fields defining the extent of the contiguous allocation region.) 1090 // But G1CollectedHeap doesn't yet support this. 1091 1092 virtual bool is_maximal_no_gc() const { 1093 return _hrm.available() == 0; 1094 } 1095 1096 // The current number of regions in the heap. 1097 uint num_regions() const { return _hrm.length(); } 1098 1099 // The max number of regions in the heap. 1100 uint max_regions() const { return _hrm.max_length(); } 1101 1102 // The number of regions that are completely free. 1103 uint num_free_regions() const { return _hrm.num_free_regions(); } 1104 1105 MemoryUsage get_auxiliary_data_memory_usage() const { 1106 return _hrm.get_auxiliary_data_memory_usage(); 1107 } 1108 1109 // The number of regions that are not completely free. 1110 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1111 1112 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1113 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1114 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1115 void verify_dirty_young_regions() PRODUCT_RETURN; 1116 1117 #ifndef PRODUCT 1118 // Make sure that the given bitmap has no marked objects in the 1119 // range [from,limit). If it does, print an error message and return 1120 // false. Otherwise, just return true. bitmap_name should be "prev" 1121 // or "next". 1122 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1123 HeapWord* from, HeapWord* limit); 1124 1125 // Verify that the prev / next bitmap range [tams,end) for the given 1126 // region has no marks. Return true if all is well, false if errors 1127 // are detected. 1128 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1129 #endif // PRODUCT 1130 1131 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1132 // the given region do not have any spurious marks. If errors are 1133 // detected, print appropriate error messages and crash. 1134 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1135 1136 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1137 // have any spurious marks. If errors are detected, print 1138 // appropriate error messages and crash. 1139 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1140 1141 // Do sanity check on the contents of the in-cset fast test table. 1142 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1143 1144 // verify_region_sets() performs verification over the region 1145 // lists. It will be compiled in the product code to be used when 1146 // necessary (i.e., during heap verification). 1147 void verify_region_sets(); 1148 1149 // verify_region_sets_optional() is planted in the code for 1150 // list verification in non-product builds (and it can be enabled in 1151 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1152 #if HEAP_REGION_SET_FORCE_VERIFY 1153 void verify_region_sets_optional() { 1154 verify_region_sets(); 1155 } 1156 #else // HEAP_REGION_SET_FORCE_VERIFY 1157 void verify_region_sets_optional() { } 1158 #endif // HEAP_REGION_SET_FORCE_VERIFY 1159 1160 #ifdef ASSERT 1161 bool is_on_master_free_list(HeapRegion* hr) { 1162 return _hrm.is_free(hr); 1163 } 1164 #endif // ASSERT 1165 1166 // Wrapper for the region list operations that can be called from 1167 // methods outside this class. 1168 1169 void secondary_free_list_add(FreeRegionList* list) { 1170 _secondary_free_list.add_ordered(list); 1171 } 1172 1173 void append_secondary_free_list() { 1174 _hrm.insert_list_into_free_list(&_secondary_free_list); 1175 } 1176 1177 void append_secondary_free_list_if_not_empty_with_lock() { 1178 // If the secondary free list looks empty there's no reason to 1179 // take the lock and then try to append it. 1180 if (!_secondary_free_list.is_empty()) { 1181 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1182 append_secondary_free_list(); 1183 } 1184 } 1185 1186 inline void old_set_remove(HeapRegion* hr); 1187 1188 size_t non_young_capacity_bytes() { 1189 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1190 } 1191 1192 void set_free_regions_coming(); 1193 void reset_free_regions_coming(); 1194 bool free_regions_coming() { return _free_regions_coming; } 1195 void wait_while_free_regions_coming(); 1196 1197 // Determine whether the given region is one that we are using as an 1198 // old GC alloc region. 1199 bool is_old_gc_alloc_region(HeapRegion* hr) { 1200 return _allocator->is_retained_old_region(hr); 1201 } 1202 1203 // Perform a collection of the heap; intended for use in implementing 1204 // "System.gc". This probably implies as full a collection as the 1205 // "CollectedHeap" supports. 1206 virtual void collect(GCCause::Cause cause); 1207 1208 // The same as above but assume that the caller holds the Heap_lock. 1209 void collect_locked(GCCause::Cause cause); 1210 1211 virtual bool copy_allocation_context_stats(const jint* contexts, 1212 jlong* totals, 1213 jbyte* accuracy, 1214 jint len); 1215 1216 // True iff an evacuation has failed in the most-recent collection. 1217 bool evacuation_failed() { return _evacuation_failed; } 1218 1219 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1220 void prepend_to_freelist(FreeRegionList* list); 1221 void decrement_summary_bytes(size_t bytes); 1222 1223 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1224 virtual bool is_in(const void* p) const; 1225 #ifdef ASSERT 1226 // Returns whether p is in one of the available areas of the heap. Slow but 1227 // extensive version. 1228 bool is_in_exact(const void* p) const; 1229 #endif 1230 1231 // Return "TRUE" iff the given object address is within the collection 1232 // set. Slow implementation. 1233 bool obj_in_cs(oop obj); 1234 1235 inline bool is_in_cset(const HeapRegion *hr); 1236 inline bool is_in_cset(oop obj); 1237 1238 inline bool is_in_cset_or_humongous(const oop obj); 1239 1240 private: 1241 // This array is used for a quick test on whether a reference points into 1242 // the collection set or not. Each of the array's elements denotes whether the 1243 // corresponding region is in the collection set or not. 1244 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1245 1246 public: 1247 1248 inline InCSetState in_cset_state(const oop obj); 1249 1250 // Return "TRUE" iff the given object address is in the reserved 1251 // region of g1. 1252 bool is_in_g1_reserved(const void* p) const { 1253 return _hrm.reserved().contains(p); 1254 } 1255 1256 // Returns a MemRegion that corresponds to the space that has been 1257 // reserved for the heap 1258 MemRegion g1_reserved() const { 1259 return _hrm.reserved(); 1260 } 1261 1262 virtual bool is_in_closed_subset(const void* p) const; 1263 1264 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1265 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1266 } 1267 1268 // This resets the card table to all zeros. It is used after 1269 // a collection pause which used the card table to claim cards. 1270 void cleanUpCardTable(); 1271 1272 // Iteration functions. 1273 1274 // Iterate over all objects, calling "cl.do_object" on each. 1275 virtual void object_iterate(ObjectClosure* cl); 1276 1277 virtual void safe_object_iterate(ObjectClosure* cl) { 1278 object_iterate(cl); 1279 } 1280 1281 // Iterate over heap regions, in address order, terminating the 1282 // iteration early if the "doHeapRegion" method returns "true". 1283 void heap_region_iterate(HeapRegionClosure* blk) const; 1284 1285 // Return the region with the given index. It assumes the index is valid. 1286 inline HeapRegion* region_at(uint index) const; 1287 1288 // Calculate the region index of the given address. Given address must be 1289 // within the heap. 1290 inline uint addr_to_region(HeapWord* addr) const; 1291 1292 inline HeapWord* bottom_addr_for_region(uint index) const; 1293 1294 // Iterate over the heap regions in parallel. Assumes that this will be called 1295 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1296 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1297 // to each of the regions, by attempting to claim the region using the 1298 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1299 // region. The concurrent argument should be set to true if iteration is 1300 // performed concurrently, during which no assumptions are made for consistent 1301 // attributes of the heap regions (as they might be modified while iterating). 1302 void heap_region_par_iterate(HeapRegionClosure* cl, 1303 uint worker_id, 1304 HeapRegionClaimer* hrclaimer, 1305 bool concurrent = false) const; 1306 1307 // Clear the cached cset start regions and (more importantly) 1308 // the time stamps. Called when we reset the GC time stamp. 1309 void clear_cset_start_regions(); 1310 1311 // Given the id of a worker, obtain or calculate a suitable 1312 // starting region for iterating over the current collection set. 1313 HeapRegion* start_cset_region_for_worker(uint worker_i); 1314 1315 // Iterate over the regions (if any) in the current collection set. 1316 void collection_set_iterate(HeapRegionClosure* blk); 1317 1318 // As above but starting from region r 1319 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1320 1321 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1322 1323 // Returns the HeapRegion that contains addr. addr must not be NULL. 1324 template <class T> 1325 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1326 1327 // Returns the HeapRegion that contains addr. addr must not be NULL. 1328 // If addr is within a humongous continues region, it returns its humongous start region. 1329 template <class T> 1330 inline HeapRegion* heap_region_containing(const T addr) const; 1331 1332 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1333 // each address in the (reserved) heap is a member of exactly 1334 // one block. The defining characteristic of a block is that it is 1335 // possible to find its size, and thus to progress forward to the next 1336 // block. (Blocks may be of different sizes.) Thus, blocks may 1337 // represent Java objects, or they might be free blocks in a 1338 // free-list-based heap (or subheap), as long as the two kinds are 1339 // distinguishable and the size of each is determinable. 1340 1341 // Returns the address of the start of the "block" that contains the 1342 // address "addr". We say "blocks" instead of "object" since some heaps 1343 // may not pack objects densely; a chunk may either be an object or a 1344 // non-object. 1345 virtual HeapWord* block_start(const void* addr) const; 1346 1347 // Requires "addr" to be the start of a chunk, and returns its size. 1348 // "addr + size" is required to be the start of a new chunk, or the end 1349 // of the active area of the heap. 1350 virtual size_t block_size(const HeapWord* addr) const; 1351 1352 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1353 // the block is an object. 1354 virtual bool block_is_obj(const HeapWord* addr) const; 1355 1356 // Section on thread-local allocation buffers (TLABs) 1357 // See CollectedHeap for semantics. 1358 1359 bool supports_tlab_allocation() const; 1360 size_t tlab_capacity(Thread* ignored) const; 1361 size_t tlab_used(Thread* ignored) const; 1362 size_t max_tlab_size() const; 1363 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1364 1365 // Can a compiler initialize a new object without store barriers? 1366 // This permission only extends from the creation of a new object 1367 // via a TLAB up to the first subsequent safepoint. If such permission 1368 // is granted for this heap type, the compiler promises to call 1369 // defer_store_barrier() below on any slow path allocation of 1370 // a new object for which such initializing store barriers will 1371 // have been elided. G1, like CMS, allows this, but should be 1372 // ready to provide a compensating write barrier as necessary 1373 // if that storage came out of a non-young region. The efficiency 1374 // of this implementation depends crucially on being able to 1375 // answer very efficiently in constant time whether a piece of 1376 // storage in the heap comes from a young region or not. 1377 // See ReduceInitialCardMarks. 1378 virtual bool can_elide_tlab_store_barriers() const { 1379 return true; 1380 } 1381 1382 virtual bool card_mark_must_follow_store() const { 1383 return true; 1384 } 1385 1386 inline bool is_in_young(const oop obj); 1387 1388 virtual bool is_scavengable(const void* addr); 1389 1390 // We don't need barriers for initializing stores to objects 1391 // in the young gen: for the SATB pre-barrier, there is no 1392 // pre-value that needs to be remembered; for the remembered-set 1393 // update logging post-barrier, we don't maintain remembered set 1394 // information for young gen objects. 1395 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1396 1397 // Returns "true" iff the given word_size is "very large". 1398 static bool is_humongous(size_t word_size) { 1399 // Note this has to be strictly greater-than as the TLABs 1400 // are capped at the humongous threshold and we want to 1401 // ensure that we don't try to allocate a TLAB as 1402 // humongous and that we don't allocate a humongous 1403 // object in a TLAB. 1404 return word_size > _humongous_object_threshold_in_words; 1405 } 1406 1407 // Returns the humongous threshold for a specific region size 1408 static size_t humongous_threshold_for(size_t region_size) { 1409 return (region_size / 2); 1410 } 1411 1412 // Update mod union table with the set of dirty cards. 1413 void updateModUnion(); 1414 1415 // Set the mod union bits corresponding to the given memRegion. Note 1416 // that this is always a safe operation, since it doesn't clear any 1417 // bits. 1418 void markModUnionRange(MemRegion mr); 1419 1420 // Print the maximum heap capacity. 1421 virtual size_t max_capacity() const; 1422 1423 virtual jlong millis_since_last_gc(); 1424 1425 1426 // Convenience function to be used in situations where the heap type can be 1427 // asserted to be this type. 1428 static G1CollectedHeap* heap(); 1429 1430 void set_region_short_lived_locked(HeapRegion* hr); 1431 // add appropriate methods for any other surv rate groups 1432 1433 YoungList* young_list() const { return _young_list; } 1434 1435 // debugging 1436 bool check_young_list_well_formed() { 1437 return _young_list->check_list_well_formed(); 1438 } 1439 1440 bool check_young_list_empty(bool check_heap, 1441 bool check_sample = true); 1442 1443 // *** Stuff related to concurrent marking. It's not clear to me that so 1444 // many of these need to be public. 1445 1446 // The functions below are helper functions that a subclass of 1447 // "CollectedHeap" can use in the implementation of its virtual 1448 // functions. 1449 // This performs a concurrent marking of the live objects in a 1450 // bitmap off to the side. 1451 void doConcurrentMark(); 1452 1453 bool isMarkedPrev(oop obj) const; 1454 bool isMarkedNext(oop obj) const; 1455 1456 // Determine if an object is dead, given the object and also 1457 // the region to which the object belongs. An object is dead 1458 // iff a) it was not allocated since the last mark, b) it 1459 // is not marked, and c) it is not in an archive region. 1460 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1461 return 1462 !hr->obj_allocated_since_prev_marking(obj) && 1463 !isMarkedPrev(obj) && 1464 !hr->is_archive(); 1465 } 1466 1467 // This function returns true when an object has been 1468 // around since the previous marking and hasn't yet 1469 // been marked during this marking, and is not in an archive region. 1470 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1471 return 1472 !hr->obj_allocated_since_next_marking(obj) && 1473 !isMarkedNext(obj) && 1474 !hr->is_archive(); 1475 } 1476 1477 // Determine if an object is dead, given only the object itself. 1478 // This will find the region to which the object belongs and 1479 // then call the region version of the same function. 1480 1481 // Added if it is NULL it isn't dead. 1482 1483 inline bool is_obj_dead(const oop obj) const; 1484 1485 inline bool is_obj_ill(const oop obj) const; 1486 1487 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1488 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1489 bool is_marked(oop obj, VerifyOption vo); 1490 const char* top_at_mark_start_str(VerifyOption vo); 1491 1492 ConcurrentMark* concurrent_mark() const { return _cm; } 1493 1494 // Refinement 1495 1496 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1497 1498 // The dirty cards region list is used to record a subset of regions 1499 // whose cards need clearing. The list if populated during the 1500 // remembered set scanning and drained during the card table 1501 // cleanup. Although the methods are reentrant, population/draining 1502 // phases must not overlap. For synchronization purposes the last 1503 // element on the list points to itself. 1504 HeapRegion* _dirty_cards_region_list; 1505 void push_dirty_cards_region(HeapRegion* hr); 1506 HeapRegion* pop_dirty_cards_region(); 1507 1508 // Optimized nmethod scanning support routines 1509 1510 // Register the given nmethod with the G1 heap. 1511 virtual void register_nmethod(nmethod* nm); 1512 1513 // Unregister the given nmethod from the G1 heap. 1514 virtual void unregister_nmethod(nmethod* nm); 1515 1516 // Free up superfluous code root memory. 1517 void purge_code_root_memory(); 1518 1519 // Rebuild the strong code root lists for each region 1520 // after a full GC. 1521 void rebuild_strong_code_roots(); 1522 1523 // Delete entries for dead interned string and clean up unreferenced symbols 1524 // in symbol table, possibly in parallel. 1525 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1526 1527 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1528 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1529 1530 // Redirty logged cards in the refinement queue. 1531 void redirty_logged_cards(); 1532 // Verification 1533 1534 // Perform any cleanup actions necessary before allowing a verification. 1535 virtual void prepare_for_verify(); 1536 1537 // Perform verification. 1538 1539 // vo == UsePrevMarking -> use "prev" marking information, 1540 // vo == UseNextMarking -> use "next" marking information 1541 // vo == UseMarkWord -> use the mark word in the object header 1542 // 1543 // NOTE: Only the "prev" marking information is guaranteed to be 1544 // consistent most of the time, so most calls to this should use 1545 // vo == UsePrevMarking. 1546 // Currently, there is only one case where this is called with 1547 // vo == UseNextMarking, which is to verify the "next" marking 1548 // information at the end of remark. 1549 // Currently there is only one place where this is called with 1550 // vo == UseMarkWord, which is to verify the marking during a 1551 // full GC. 1552 void verify(bool silent, VerifyOption vo); 1553 1554 // Override; it uses the "prev" marking information 1555 virtual void verify(bool silent); 1556 1557 // The methods below are here for convenience and dispatch the 1558 // appropriate method depending on value of the given VerifyOption 1559 // parameter. The values for that parameter, and their meanings, 1560 // are the same as those above. 1561 1562 bool is_obj_dead_cond(const oop obj, 1563 const HeapRegion* hr, 1564 const VerifyOption vo) const; 1565 1566 bool is_obj_dead_cond(const oop obj, 1567 const VerifyOption vo) const; 1568 1569 G1HeapSummary create_g1_heap_summary(); 1570 1571 // Printing 1572 1573 virtual void print_on(outputStream* st) const; 1574 virtual void print_extended_on(outputStream* st) const; 1575 virtual void print_on_error(outputStream* st) const; 1576 1577 virtual void print_gc_threads_on(outputStream* st) const; 1578 virtual void gc_threads_do(ThreadClosure* tc) const; 1579 1580 // Override 1581 void print_tracing_info() const; 1582 1583 // The following two methods are helpful for debugging RSet issues. 1584 void print_cset_rsets() PRODUCT_RETURN; 1585 void print_all_rsets() PRODUCT_RETURN; 1586 1587 public: 1588 size_t pending_card_num(); 1589 size_t cards_scanned(); 1590 1591 protected: 1592 size_t _max_heap_capacity; 1593 }; 1594 1595 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP