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 // Do we have more free regions to allocate into? 544 inline bool has_more_free_regions() const; 545 546 // These methods are the "callbacks" from the G1AllocRegion class. 547 548 // For mutator alloc regions. 549 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 550 void retire_mutator_alloc_region(HeapRegion* alloc_region, 551 size_t allocated_bytes); 552 553 // For GC alloc regions. 554 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 555 InCSetState dest); 556 void retire_gc_alloc_region(HeapRegion* alloc_region, 557 size_t allocated_bytes, InCSetState dest); 558 559 // Allocate the highest free region in the reserved heap. This will commit 560 // regions as necessary. 561 HeapRegion* alloc_highest_free_region(); 562 563 // - if explicit_gc is true, the GC is for a System.gc() or a heap 564 // inspection request and should collect the entire heap 565 // - if clear_all_soft_refs is true, all soft references should be 566 // cleared during the GC 567 // - if explicit_gc is false, word_size describes the allocation that 568 // the GC should attempt (at least) to satisfy 569 // - it returns false if it is unable to do the collection due to the 570 // GC locker being active, true otherwise 571 bool do_collection(bool explicit_gc, 572 bool clear_all_soft_refs, 573 size_t word_size); 574 575 // Callback from VM_G1CollectFull operation. 576 // Perform a full collection. 577 virtual void do_full_collection(bool clear_all_soft_refs); 578 579 // Resize the heap if necessary after a full collection. If this is 580 // after a collect-for allocation, "word_size" is the allocation size, 581 // and will be considered part of the used portion of the heap. 582 void resize_if_necessary_after_full_collection(size_t word_size); 583 584 // Callback from VM_G1CollectForAllocation operation. 585 // This function does everything necessary/possible to satisfy a 586 // failed allocation request (including collection, expansion, etc.) 587 HeapWord* satisfy_failed_allocation(size_t word_size, 588 AllocationContext_t context, 589 bool* succeeded); 590 591 // Attempting to expand the heap sufficiently 592 // to support an allocation of the given "word_size". If 593 // successful, perform the allocation and return the address of the 594 // allocated block, or else "NULL". 595 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 596 597 // Process any reference objects discovered during 598 // an incremental evacuation pause. 599 void process_discovered_references(); 600 601 // Enqueue any remaining discovered references 602 // after processing. 603 void enqueue_discovered_references(); 604 605 public: 606 FlexibleWorkGang* workers() const { return _workers; } 607 608 G1Allocator* allocator() { 609 return _allocator; 610 } 611 612 G1MonitoringSupport* g1mm() { 613 assert(_g1mm != NULL, "should have been initialized"); 614 return _g1mm; 615 } 616 617 // Expand the garbage-first heap by at least the given size (in bytes!). 618 // Returns true if the heap was expanded by the requested amount; 619 // false otherwise. 620 // (Rounds up to a HeapRegion boundary.) 621 bool expand(size_t expand_bytes); 622 623 // Returns the PLAB statistics for a given destination. 624 inline PLABStats* alloc_buffer_stats(InCSetState dest); 625 626 // Determines PLAB size for a given destination. 627 inline size_t desired_plab_sz(InCSetState dest); 628 629 inline AllocationContextStats& allocation_context_stats(); 630 631 // Do anything common to GC's. 632 void gc_prologue(bool full); 633 void gc_epilogue(bool full); 634 635 // Modify the reclaim candidate set and test for presence. 636 // These are only valid for starts_humongous regions. 637 inline void set_humongous_reclaim_candidate(uint region, bool value); 638 inline bool is_humongous_reclaim_candidate(uint region); 639 640 // Remove from the reclaim candidate set. Also remove from the 641 // collection set so that later encounters avoid the slow path. 642 inline void set_humongous_is_live(oop obj); 643 644 // Register the given region to be part of the collection set. 645 inline void register_humongous_region_with_cset(uint index); 646 // Register regions with humongous objects (actually on the start region) in 647 // the in_cset_fast_test table. 648 void register_humongous_regions_with_cset(); 649 // We register a region with the fast "in collection set" test. We 650 // simply set to true the array slot corresponding to this region. 651 void register_young_region_with_cset(HeapRegion* r) { 652 _in_cset_fast_test.set_in_young(r->hrm_index()); 653 } 654 void register_old_region_with_cset(HeapRegion* r) { 655 _in_cset_fast_test.set_in_old(r->hrm_index()); 656 } 657 void clear_in_cset(const HeapRegion* hr) { 658 _in_cset_fast_test.clear(hr); 659 } 660 661 void clear_cset_fast_test() { 662 _in_cset_fast_test.clear(); 663 } 664 665 // This is called at the start of either a concurrent cycle or a Full 666 // GC to update the number of old marking cycles started. 667 void increment_old_marking_cycles_started(); 668 669 // This is called at the end of either a concurrent cycle or a Full 670 // GC to update the number of old marking cycles completed. Those two 671 // can happen in a nested fashion, i.e., we start a concurrent 672 // cycle, a Full GC happens half-way through it which ends first, 673 // and then the cycle notices that a Full GC happened and ends 674 // too. The concurrent parameter is a boolean to help us do a bit 675 // tighter consistency checking in the method. If concurrent is 676 // false, the caller is the inner caller in the nesting (i.e., the 677 // Full GC). If concurrent is true, the caller is the outer caller 678 // in this nesting (i.e., the concurrent cycle). Further nesting is 679 // not currently supported. The end of this call also notifies 680 // the FullGCCount_lock in case a Java thread is waiting for a full 681 // GC to happen (e.g., it called System.gc() with 682 // +ExplicitGCInvokesConcurrent). 683 void increment_old_marking_cycles_completed(bool concurrent); 684 685 uint old_marking_cycles_completed() { 686 return _old_marking_cycles_completed; 687 } 688 689 void register_concurrent_cycle_start(const Ticks& start_time); 690 void register_concurrent_cycle_end(); 691 void trace_heap_after_concurrent_cycle(); 692 693 G1HRPrinter* hr_printer() { return &_hr_printer; } 694 695 // Allocates a new heap region instance. 696 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 697 698 // Frees a non-humongous region by initializing its contents and 699 // adding it to the free list that's passed as a parameter (this is 700 // usually a local list which will be appended to the master free 701 // list later). The used bytes of freed regions are accumulated in 702 // pre_used. If par is true, the region's RSet will not be freed 703 // up. The assumption is that this will be done later. 704 // The locked parameter indicates if the caller has already taken 705 // care of proper synchronization. This may allow some optimizations. 706 void free_region(HeapRegion* hr, 707 FreeRegionList* free_list, 708 bool par, 709 bool locked = false); 710 711 // Frees a humongous region by collapsing it into individual regions 712 // and calling free_region() for each of them. The freed regions 713 // will be added to the free list that's passed as a parameter (this 714 // is usually a local list which will be appended to the master free 715 // list later). The used bytes of freed regions are accumulated in 716 // pre_used. If par is true, the region's RSet will not be freed 717 // up. The assumption is that this will be done later. 718 void free_humongous_region(HeapRegion* hr, 719 FreeRegionList* free_list, 720 bool par); 721 722 // Facility for allocating in 'archive' regions in high heap memory and 723 // recording the allocated ranges. These should all be called from the 724 // VM thread at safepoints, without the heap lock held. They can be used 725 // to create and archive a set of heap regions which can be mapped at the 726 // same fixed addresses in a subsequent JVM invocation. 727 void begin_archive_alloc_range(); 728 729 // Check if the requested size would be too large for an archive allocation. 730 bool is_archive_alloc_too_large(size_t word_size); 731 732 // Allocate memory of the requested size from the archive region. This will 733 // return NULL if the size is too large or if no memory is available. It 734 // does not trigger a garbage collection. 735 HeapWord* archive_mem_allocate(size_t word_size); 736 737 // Optionally aligns the end address and returns the allocated ranges in 738 // an array of MemRegions in order of ascending addresses. 739 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 740 size_t end_alignment_in_bytes = 0); 741 742 // Facility for allocating a fixed range within the heap and marking 743 // the containing regions as 'archive'. For use at JVM init time, when the 744 // caller may mmap archived heap data at the specified range(s). 745 // Verify that the MemRegions specified in the argument array are within the 746 // reserved heap. 747 bool check_archive_addresses(MemRegion* range, size_t count); 748 749 // Commit the appropriate G1 regions containing the specified MemRegions 750 // and mark them as 'archive' regions. The regions in the array must be 751 // non-overlapping and in order of ascending address. 752 bool alloc_archive_regions(MemRegion* range, size_t count); 753 754 // Insert any required filler objects in the G1 regions around the specified 755 // ranges to make the regions parseable. This must be called after 756 // alloc_archive_regions, and after class loading has occurred. 757 void fill_archive_regions(MemRegion* range, size_t count); 758 759 protected: 760 761 // Shrink the garbage-first heap by at most the given size (in bytes!). 762 // (Rounds down to a HeapRegion boundary.) 763 virtual void shrink(size_t expand_bytes); 764 void shrink_helper(size_t expand_bytes); 765 766 #if TASKQUEUE_STATS 767 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 768 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 769 void reset_taskqueue_stats(); 770 #endif // TASKQUEUE_STATS 771 772 // Schedule the VM operation that will do an evacuation pause to 773 // satisfy an allocation request of word_size. *succeeded will 774 // return whether the VM operation was successful (it did do an 775 // evacuation pause) or not (another thread beat us to it or the GC 776 // locker was active). Given that we should not be holding the 777 // Heap_lock when we enter this method, we will pass the 778 // gc_count_before (i.e., total_collections()) as a parameter since 779 // it has to be read while holding the Heap_lock. Currently, both 780 // methods that call do_collection_pause() release the Heap_lock 781 // before the call, so it's easy to read gc_count_before just before. 782 HeapWord* do_collection_pause(size_t word_size, 783 uint gc_count_before, 784 bool* succeeded, 785 GCCause::Cause gc_cause); 786 787 void wait_for_root_region_scanning(); 788 789 // The guts of the incremental collection pause, executed by the vm 790 // thread. It returns false if it is unable to do the collection due 791 // to the GC locker being active, true otherwise 792 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 793 794 // Actually do the work of evacuating the collection set. 795 void evacuate_collection_set(EvacuationInfo& evacuation_info); 796 797 // The g1 remembered set of the heap. 798 G1RemSet* _g1_rem_set; 799 800 // A set of cards that cover the objects for which the Rsets should be updated 801 // concurrently after the collection. 802 DirtyCardQueueSet _dirty_card_queue_set; 803 804 // The closure used to refine a single card. 805 RefineCardTableEntryClosure* _refine_cte_cl; 806 807 // A DirtyCardQueueSet that is used to hold cards that contain 808 // references into the current collection set. This is used to 809 // update the remembered sets of the regions in the collection 810 // set in the event of an evacuation failure. 811 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 812 813 // After a collection pause, make the regions in the CS into free 814 // regions. 815 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 816 817 // Abandon the current collection set without recording policy 818 // statistics or updating free lists. 819 void abandon_collection_set(HeapRegion* cs_head); 820 821 // The concurrent marker (and the thread it runs in.) 822 ConcurrentMark* _cm; 823 ConcurrentMarkThread* _cmThread; 824 825 // The concurrent refiner. 826 ConcurrentG1Refine* _cg1r; 827 828 // The parallel task queues 829 RefToScanQueueSet *_task_queues; 830 831 // True iff a evacuation has failed in the current collection. 832 bool _evacuation_failed; 833 834 EvacuationFailedInfo* _evacuation_failed_info_array; 835 836 // Failed evacuations cause some logical from-space objects to have 837 // forwarding pointers to themselves. Reset them. 838 void remove_self_forwarding_pointers(); 839 840 struct OopAndMarkOop { 841 private: 842 oop _o; 843 markOop _m; 844 public: 845 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { 846 } 847 848 void set_mark() { 849 _o->set_mark(_m); 850 } 851 }; 852 853 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack; 854 // Stores marks with the corresponding oop that we need to preserve during evacuation 855 // failure. 856 OopAndMarkOopStack* _preserved_objs; 857 858 // Preserve the mark of "obj", if necessary, in preparation for its mark 859 // word being overwritten with a self-forwarding-pointer. 860 void preserve_mark_during_evac_failure(uint queue, oop obj, markOop m); 861 862 #ifndef PRODUCT 863 // Support for forcing evacuation failures. Analogous to 864 // PromotionFailureALot for the other collectors. 865 866 // Records whether G1EvacuationFailureALot should be in effect 867 // for the current GC 868 bool _evacuation_failure_alot_for_current_gc; 869 870 // Used to record the GC number for interval checking when 871 // determining whether G1EvaucationFailureALot is in effect 872 // for the current GC. 873 size_t _evacuation_failure_alot_gc_number; 874 875 // Count of the number of evacuations between failures. 876 volatile size_t _evacuation_failure_alot_count; 877 878 // Set whether G1EvacuationFailureALot should be in effect 879 // for the current GC (based upon the type of GC and which 880 // command line flags are set); 881 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 882 bool during_initial_mark, 883 bool during_marking); 884 885 inline void set_evacuation_failure_alot_for_current_gc(); 886 887 // Return true if it's time to cause an evacuation failure. 888 inline bool evacuation_should_fail(); 889 890 // Reset the G1EvacuationFailureALot counters. Should be called at 891 // the end of an evacuation pause in which an evacuation failure occurred. 892 inline void reset_evacuation_should_fail(); 893 #endif // !PRODUCT 894 895 // ("Weak") Reference processing support. 896 // 897 // G1 has 2 instances of the reference processor class. One 898 // (_ref_processor_cm) handles reference object discovery 899 // and subsequent processing during concurrent marking cycles. 900 // 901 // The other (_ref_processor_stw) handles reference object 902 // discovery and processing during full GCs and incremental 903 // evacuation pauses. 904 // 905 // During an incremental pause, reference discovery will be 906 // temporarily disabled for _ref_processor_cm and will be 907 // enabled for _ref_processor_stw. At the end of the evacuation 908 // pause references discovered by _ref_processor_stw will be 909 // processed and discovery will be disabled. The previous 910 // setting for reference object discovery for _ref_processor_cm 911 // will be re-instated. 912 // 913 // At the start of marking: 914 // * Discovery by the CM ref processor is verified to be inactive 915 // and it's discovered lists are empty. 916 // * Discovery by the CM ref processor is then enabled. 917 // 918 // At the end of marking: 919 // * Any references on the CM ref processor's discovered 920 // lists are processed (possibly MT). 921 // 922 // At the start of full GC we: 923 // * Disable discovery by the CM ref processor and 924 // empty CM ref processor's discovered lists 925 // (without processing any entries). 926 // * Verify that the STW ref processor is inactive and it's 927 // discovered lists are empty. 928 // * Temporarily set STW ref processor discovery as single threaded. 929 // * Temporarily clear the STW ref processor's _is_alive_non_header 930 // field. 931 // * Finally enable discovery by the STW ref processor. 932 // 933 // The STW ref processor is used to record any discovered 934 // references during the full GC. 935 // 936 // At the end of a full GC we: 937 // * Enqueue any reference objects discovered by the STW ref processor 938 // that have non-live referents. This has the side-effect of 939 // making the STW ref processor inactive by disabling discovery. 940 // * Verify that the CM ref processor is still inactive 941 // and no references have been placed on it's discovered 942 // lists (also checked as a precondition during initial marking). 943 944 // The (stw) reference processor... 945 ReferenceProcessor* _ref_processor_stw; 946 947 STWGCTimer* _gc_timer_stw; 948 ConcurrentGCTimer* _gc_timer_cm; 949 950 G1OldTracer* _gc_tracer_cm; 951 G1NewTracer* _gc_tracer_stw; 952 953 // During reference object discovery, the _is_alive_non_header 954 // closure (if non-null) is applied to the referent object to 955 // determine whether the referent is live. If so then the 956 // reference object does not need to be 'discovered' and can 957 // be treated as a regular oop. This has the benefit of reducing 958 // the number of 'discovered' reference objects that need to 959 // be processed. 960 // 961 // Instance of the is_alive closure for embedding into the 962 // STW reference processor as the _is_alive_non_header field. 963 // Supplying a value for the _is_alive_non_header field is 964 // optional but doing so prevents unnecessary additions to 965 // the discovered lists during reference discovery. 966 G1STWIsAliveClosure _is_alive_closure_stw; 967 968 // The (concurrent marking) reference processor... 969 ReferenceProcessor* _ref_processor_cm; 970 971 // Instance of the concurrent mark is_alive closure for embedding 972 // into the Concurrent Marking reference processor as the 973 // _is_alive_non_header field. Supplying a value for the 974 // _is_alive_non_header field is optional but doing so prevents 975 // unnecessary additions to the discovered lists during reference 976 // discovery. 977 G1CMIsAliveClosure _is_alive_closure_cm; 978 979 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 980 HeapRegion** _worker_cset_start_region; 981 982 // Time stamp to validate the regions recorded in the cache 983 // used by G1CollectedHeap::start_cset_region_for_worker(). 984 // The heap region entry for a given worker is valid iff 985 // the associated time stamp value matches the current value 986 // of G1CollectedHeap::_gc_time_stamp. 987 uint* _worker_cset_start_region_time_stamp; 988 989 volatile bool _free_regions_coming; 990 991 public: 992 993 void set_refine_cte_cl_concurrency(bool concurrent); 994 995 RefToScanQueue *task_queue(uint i) const; 996 997 uint num_task_queues() const; 998 999 // A set of cards where updates happened during the GC 1000 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1001 1002 // A DirtyCardQueueSet that is used to hold cards that contain 1003 // references into the current collection set. This is used to 1004 // update the remembered sets of the regions in the collection 1005 // set in the event of an evacuation failure. 1006 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1007 { return _into_cset_dirty_card_queue_set; } 1008 1009 // Create a G1CollectedHeap with the specified policy. 1010 // Must call the initialize method afterwards. 1011 // May not return if something goes wrong. 1012 G1CollectedHeap(G1CollectorPolicy* policy); 1013 1014 // Initialize the G1CollectedHeap to have the initial and 1015 // maximum sizes and remembered and barrier sets 1016 // specified by the policy object. 1017 jint initialize(); 1018 1019 virtual void stop(); 1020 1021 // Return the (conservative) maximum heap alignment for any G1 heap 1022 static size_t conservative_max_heap_alignment(); 1023 1024 // Does operations required after initialization has been done. 1025 void post_initialize(); 1026 1027 // Initialize weak reference processing. 1028 void ref_processing_init(); 1029 1030 virtual Name kind() const { 1031 return CollectedHeap::G1CollectedHeap; 1032 } 1033 1034 G1CollectorState* collector_state() { return &_collector_state; } 1035 1036 // The current policy object for the collector. 1037 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1038 1039 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1040 1041 // Adaptive size policy. No such thing for g1. 1042 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1043 1044 // The rem set and barrier set. 1045 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1046 1047 unsigned get_gc_time_stamp() { 1048 return _gc_time_stamp; 1049 } 1050 1051 inline void reset_gc_time_stamp(); 1052 1053 void check_gc_time_stamps() PRODUCT_RETURN; 1054 1055 inline void increment_gc_time_stamp(); 1056 1057 // Reset the given region's GC timestamp. If it's starts humongous, 1058 // also reset the GC timestamp of its corresponding 1059 // continues humongous regions too. 1060 void reset_gc_time_stamps(HeapRegion* hr); 1061 1062 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1063 DirtyCardQueue* into_cset_dcq, 1064 bool concurrent, uint worker_i); 1065 1066 // The shared block offset table array. 1067 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1068 1069 // Reference Processing accessors 1070 1071 // The STW reference processor.... 1072 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1073 1074 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1075 1076 // The Concurrent Marking reference processor... 1077 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1078 1079 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1080 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1081 1082 virtual size_t capacity() const; 1083 virtual size_t used() const; 1084 // This should be called when we're not holding the heap lock. The 1085 // result might be a bit inaccurate. 1086 size_t used_unlocked() const; 1087 size_t recalculate_used() const; 1088 1089 // These virtual functions do the actual allocation. 1090 // Some heaps may offer a contiguous region for shared non-blocking 1091 // allocation, via inlined code (by exporting the address of the top and 1092 // end fields defining the extent of the contiguous allocation region.) 1093 // But G1CollectedHeap doesn't yet support this. 1094 1095 virtual bool is_maximal_no_gc() const { 1096 return _hrm.available() == 0; 1097 } 1098 1099 // The current number of regions in the heap. 1100 uint num_regions() const { return _hrm.length(); } 1101 1102 // The max number of regions in the heap. 1103 uint max_regions() const { return _hrm.max_length(); } 1104 1105 // The number of regions that are completely free. 1106 uint num_free_regions() const { return _hrm.num_free_regions(); } 1107 1108 MemoryUsage get_auxiliary_data_memory_usage() const { 1109 return _hrm.get_auxiliary_data_memory_usage(); 1110 } 1111 1112 // The number of regions that are not completely free. 1113 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1114 1115 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1116 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1117 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1118 void verify_dirty_young_regions() PRODUCT_RETURN; 1119 1120 #ifndef PRODUCT 1121 // Make sure that the given bitmap has no marked objects in the 1122 // range [from,limit). If it does, print an error message and return 1123 // false. Otherwise, just return true. bitmap_name should be "prev" 1124 // or "next". 1125 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1126 HeapWord* from, HeapWord* limit); 1127 1128 // Verify that the prev / next bitmap range [tams,end) for the given 1129 // region has no marks. Return true if all is well, false if errors 1130 // are detected. 1131 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1132 #endif // PRODUCT 1133 1134 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1135 // the given region do not have any spurious marks. If errors are 1136 // detected, print appropriate error messages and crash. 1137 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1138 1139 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1140 // have any spurious marks. If errors are detected, print 1141 // appropriate error messages and crash. 1142 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1143 1144 // Do sanity check on the contents of the in-cset fast test table. 1145 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1146 1147 // verify_region_sets() performs verification over the region 1148 // lists. It will be compiled in the product code to be used when 1149 // necessary (i.e., during heap verification). 1150 void verify_region_sets(); 1151 1152 // verify_region_sets_optional() is planted in the code for 1153 // list verification in non-product builds (and it can be enabled in 1154 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1155 #if HEAP_REGION_SET_FORCE_VERIFY 1156 void verify_region_sets_optional() { 1157 verify_region_sets(); 1158 } 1159 #else // HEAP_REGION_SET_FORCE_VERIFY 1160 void verify_region_sets_optional() { } 1161 #endif // HEAP_REGION_SET_FORCE_VERIFY 1162 1163 #ifdef ASSERT 1164 bool is_on_master_free_list(HeapRegion* hr) { 1165 return _hrm.is_free(hr); 1166 } 1167 #endif // ASSERT 1168 1169 // Wrapper for the region list operations that can be called from 1170 // methods outside this class. 1171 1172 void secondary_free_list_add(FreeRegionList* list) { 1173 _secondary_free_list.add_ordered(list); 1174 } 1175 1176 void append_secondary_free_list() { 1177 _hrm.insert_list_into_free_list(&_secondary_free_list); 1178 } 1179 1180 void append_secondary_free_list_if_not_empty_with_lock() { 1181 // If the secondary free list looks empty there's no reason to 1182 // take the lock and then try to append it. 1183 if (!_secondary_free_list.is_empty()) { 1184 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1185 append_secondary_free_list(); 1186 } 1187 } 1188 1189 inline void old_set_remove(HeapRegion* hr); 1190 1191 size_t non_young_capacity_bytes() { 1192 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1193 } 1194 1195 void set_free_regions_coming(); 1196 void reset_free_regions_coming(); 1197 bool free_regions_coming() { return _free_regions_coming; } 1198 void wait_while_free_regions_coming(); 1199 1200 // Determine whether the given region is one that we are using as an 1201 // old GC alloc region. 1202 bool is_old_gc_alloc_region(HeapRegion* hr) { 1203 return _allocator->is_retained_old_region(hr); 1204 } 1205 1206 // Perform a collection of the heap; intended for use in implementing 1207 // "System.gc". This probably implies as full a collection as the 1208 // "CollectedHeap" supports. 1209 virtual void collect(GCCause::Cause cause); 1210 1211 // The same as above but assume that the caller holds the Heap_lock. 1212 void collect_locked(GCCause::Cause cause); 1213 1214 virtual bool copy_allocation_context_stats(const jint* contexts, 1215 jlong* totals, 1216 jbyte* accuracy, 1217 jint len); 1218 1219 // True iff an evacuation has failed in the most-recent collection. 1220 bool evacuation_failed() { return _evacuation_failed; } 1221 1222 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1223 void prepend_to_freelist(FreeRegionList* list); 1224 void decrement_summary_bytes(size_t bytes); 1225 1226 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1227 virtual bool is_in(const void* p) const; 1228 #ifdef ASSERT 1229 // Returns whether p is in one of the available areas of the heap. Slow but 1230 // extensive version. 1231 bool is_in_exact(const void* p) const; 1232 #endif 1233 1234 // Return "TRUE" iff the given object address is within the collection 1235 // set. Slow implementation. 1236 bool obj_in_cs(oop obj); 1237 1238 inline bool is_in_cset(const HeapRegion *hr); 1239 inline bool is_in_cset(oop obj); 1240 1241 inline bool is_in_cset_or_humongous(const oop obj); 1242 1243 private: 1244 // This array is used for a quick test on whether a reference points into 1245 // the collection set or not. Each of the array's elements denotes whether the 1246 // corresponding region is in the collection set or not. 1247 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1248 1249 public: 1250 1251 inline InCSetState in_cset_state(const oop obj); 1252 1253 // Return "TRUE" iff the given object address is in the reserved 1254 // region of g1. 1255 bool is_in_g1_reserved(const void* p) const { 1256 return _hrm.reserved().contains(p); 1257 } 1258 1259 // Returns a MemRegion that corresponds to the space that has been 1260 // reserved for the heap 1261 MemRegion g1_reserved() const { 1262 return _hrm.reserved(); 1263 } 1264 1265 virtual bool is_in_closed_subset(const void* p) const; 1266 1267 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1268 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1269 } 1270 1271 // This resets the card table to all zeros. It is used after 1272 // a collection pause which used the card table to claim cards. 1273 void cleanUpCardTable(); 1274 1275 // Iteration functions. 1276 1277 // Iterate over all objects, calling "cl.do_object" on each. 1278 virtual void object_iterate(ObjectClosure* cl); 1279 1280 virtual void safe_object_iterate(ObjectClosure* cl) { 1281 object_iterate(cl); 1282 } 1283 1284 // Iterate over heap regions, in address order, terminating the 1285 // iteration early if the "doHeapRegion" method returns "true". 1286 void heap_region_iterate(HeapRegionClosure* blk) const; 1287 1288 // Return the region with the given index. It assumes the index is valid. 1289 inline HeapRegion* region_at(uint index) const; 1290 1291 // Calculate the region index of the given address. Given address must be 1292 // within the heap. 1293 inline uint addr_to_region(HeapWord* addr) const; 1294 1295 inline HeapWord* bottom_addr_for_region(uint index) const; 1296 1297 // Iterate over the heap regions in parallel. Assumes that this will be called 1298 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1299 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1300 // to each of the regions, by attempting to claim the region using the 1301 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1302 // region. The concurrent argument should be set to true if iteration is 1303 // performed concurrently, during which no assumptions are made for consistent 1304 // attributes of the heap regions (as they might be modified while iterating). 1305 void heap_region_par_iterate(HeapRegionClosure* cl, 1306 uint worker_id, 1307 HeapRegionClaimer* hrclaimer, 1308 bool concurrent = false) const; 1309 1310 // Clear the cached cset start regions and (more importantly) 1311 // the time stamps. Called when we reset the GC time stamp. 1312 void clear_cset_start_regions(); 1313 1314 // Given the id of a worker, obtain or calculate a suitable 1315 // starting region for iterating over the current collection set. 1316 HeapRegion* start_cset_region_for_worker(uint worker_i); 1317 1318 // Iterate over the regions (if any) in the current collection set. 1319 void collection_set_iterate(HeapRegionClosure* blk); 1320 1321 // As above but starting from region r 1322 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1323 1324 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1325 1326 // Returns the HeapRegion that contains addr. addr must not be NULL. 1327 template <class T> 1328 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1329 1330 // Returns the HeapRegion that contains addr. addr must not be NULL. 1331 // If addr is within a humongous continues region, it returns its humongous start region. 1332 template <class T> 1333 inline HeapRegion* heap_region_containing(const T addr) const; 1334 1335 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1336 // each address in the (reserved) heap is a member of exactly 1337 // one block. The defining characteristic of a block is that it is 1338 // possible to find its size, and thus to progress forward to the next 1339 // block. (Blocks may be of different sizes.) Thus, blocks may 1340 // represent Java objects, or they might be free blocks in a 1341 // free-list-based heap (or subheap), as long as the two kinds are 1342 // distinguishable and the size of each is determinable. 1343 1344 // Returns the address of the start of the "block" that contains the 1345 // address "addr". We say "blocks" instead of "object" since some heaps 1346 // may not pack objects densely; a chunk may either be an object or a 1347 // non-object. 1348 virtual HeapWord* block_start(const void* addr) const; 1349 1350 // Requires "addr" to be the start of a chunk, and returns its size. 1351 // "addr + size" is required to be the start of a new chunk, or the end 1352 // of the active area of the heap. 1353 virtual size_t block_size(const HeapWord* addr) const; 1354 1355 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1356 // the block is an object. 1357 virtual bool block_is_obj(const HeapWord* addr) const; 1358 1359 // Section on thread-local allocation buffers (TLABs) 1360 // See CollectedHeap for semantics. 1361 1362 bool supports_tlab_allocation() const; 1363 size_t tlab_capacity(Thread* ignored) const; 1364 size_t tlab_used(Thread* ignored) const; 1365 size_t max_tlab_size() const; 1366 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1367 1368 // Can a compiler initialize a new object without store barriers? 1369 // This permission only extends from the creation of a new object 1370 // via a TLAB up to the first subsequent safepoint. If such permission 1371 // is granted for this heap type, the compiler promises to call 1372 // defer_store_barrier() below on any slow path allocation of 1373 // a new object for which such initializing store barriers will 1374 // have been elided. G1, like CMS, allows this, but should be 1375 // ready to provide a compensating write barrier as necessary 1376 // if that storage came out of a non-young region. The efficiency 1377 // of this implementation depends crucially on being able to 1378 // answer very efficiently in constant time whether a piece of 1379 // storage in the heap comes from a young region or not. 1380 // See ReduceInitialCardMarks. 1381 virtual bool can_elide_tlab_store_barriers() const { 1382 return true; 1383 } 1384 1385 virtual bool card_mark_must_follow_store() const { 1386 return true; 1387 } 1388 1389 inline bool is_in_young(const oop obj); 1390 1391 virtual bool is_scavengable(const void* addr); 1392 1393 // We don't need barriers for initializing stores to objects 1394 // in the young gen: for the SATB pre-barrier, there is no 1395 // pre-value that needs to be remembered; for the remembered-set 1396 // update logging post-barrier, we don't maintain remembered set 1397 // information for young gen objects. 1398 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1399 1400 // Returns "true" iff the given word_size is "very large". 1401 static bool is_humongous(size_t word_size) { 1402 // Note this has to be strictly greater-than as the TLABs 1403 // are capped at the humongous threshold and we want to 1404 // ensure that we don't try to allocate a TLAB as 1405 // humongous and that we don't allocate a humongous 1406 // object in a TLAB. 1407 return word_size > _humongous_object_threshold_in_words; 1408 } 1409 1410 // Returns the humongous threshold for a specific region size 1411 static size_t humongous_threshold_for(size_t region_size) { 1412 return (region_size / 2); 1413 } 1414 1415 // Update mod union table with the set of dirty cards. 1416 void updateModUnion(); 1417 1418 // Set the mod union bits corresponding to the given memRegion. Note 1419 // that this is always a safe operation, since it doesn't clear any 1420 // bits. 1421 void markModUnionRange(MemRegion mr); 1422 1423 // Print the maximum heap capacity. 1424 virtual size_t max_capacity() const; 1425 1426 virtual jlong millis_since_last_gc(); 1427 1428 1429 // Convenience function to be used in situations where the heap type can be 1430 // asserted to be this type. 1431 static G1CollectedHeap* heap(); 1432 1433 void set_region_short_lived_locked(HeapRegion* hr); 1434 // add appropriate methods for any other surv rate groups 1435 1436 YoungList* young_list() const { return _young_list; } 1437 1438 // debugging 1439 bool check_young_list_well_formed() { 1440 return _young_list->check_list_well_formed(); 1441 } 1442 1443 bool check_young_list_empty(bool check_heap, 1444 bool check_sample = true); 1445 1446 // *** Stuff related to concurrent marking. It's not clear to me that so 1447 // many of these need to be public. 1448 1449 // The functions below are helper functions that a subclass of 1450 // "CollectedHeap" can use in the implementation of its virtual 1451 // functions. 1452 // This performs a concurrent marking of the live objects in a 1453 // bitmap off to the side. 1454 void doConcurrentMark(); 1455 1456 bool isMarkedPrev(oop obj) const; 1457 bool isMarkedNext(oop obj) const; 1458 1459 // Determine if an object is dead, given the object and also 1460 // the region to which the object belongs. An object is dead 1461 // iff a) it was not allocated since the last mark, b) it 1462 // is not marked, and c) it is not in an archive region. 1463 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1464 return 1465 !hr->obj_allocated_since_prev_marking(obj) && 1466 !isMarkedPrev(obj) && 1467 !hr->is_archive(); 1468 } 1469 1470 // This function returns true when an object has been 1471 // around since the previous marking and hasn't yet 1472 // been marked during this marking, and is not in an archive region. 1473 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1474 return 1475 !hr->obj_allocated_since_next_marking(obj) && 1476 !isMarkedNext(obj) && 1477 !hr->is_archive(); 1478 } 1479 1480 // Determine if an object is dead, given only the object itself. 1481 // This will find the region to which the object belongs and 1482 // then call the region version of the same function. 1483 1484 // Added if it is NULL it isn't dead. 1485 1486 inline bool is_obj_dead(const oop obj) const; 1487 1488 inline bool is_obj_ill(const oop obj) const; 1489 1490 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1491 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1492 bool is_marked(oop obj, VerifyOption vo); 1493 const char* top_at_mark_start_str(VerifyOption vo); 1494 1495 ConcurrentMark* concurrent_mark() const { return _cm; } 1496 1497 // Refinement 1498 1499 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1500 1501 // The dirty cards region list is used to record a subset of regions 1502 // whose cards need clearing. The list if populated during the 1503 // remembered set scanning and drained during the card table 1504 // cleanup. Although the methods are reentrant, population/draining 1505 // phases must not overlap. For synchronization purposes the last 1506 // element on the list points to itself. 1507 HeapRegion* _dirty_cards_region_list; 1508 void push_dirty_cards_region(HeapRegion* hr); 1509 HeapRegion* pop_dirty_cards_region(); 1510 1511 // Optimized nmethod scanning support routines 1512 1513 // Register the given nmethod with the G1 heap. 1514 virtual void register_nmethod(nmethod* nm); 1515 1516 // Unregister the given nmethod from the G1 heap. 1517 virtual void unregister_nmethod(nmethod* nm); 1518 1519 // Free up superfluous code root memory. 1520 void purge_code_root_memory(); 1521 1522 // Rebuild the strong code root lists for each region 1523 // after a full GC. 1524 void rebuild_strong_code_roots(); 1525 1526 // Delete entries for dead interned string and clean up unreferenced symbols 1527 // in symbol table, possibly in parallel. 1528 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1529 1530 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1531 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1532 1533 // Redirty logged cards in the refinement queue. 1534 void redirty_logged_cards(); 1535 // Verification 1536 1537 // Perform any cleanup actions necessary before allowing a verification. 1538 virtual void prepare_for_verify(); 1539 1540 // Perform verification. 1541 1542 // vo == UsePrevMarking -> use "prev" marking information, 1543 // vo == UseNextMarking -> use "next" marking information 1544 // vo == UseMarkWord -> use the mark word in the object header 1545 // 1546 // NOTE: Only the "prev" marking information is guaranteed to be 1547 // consistent most of the time, so most calls to this should use 1548 // vo == UsePrevMarking. 1549 // Currently, there is only one case where this is called with 1550 // vo == UseNextMarking, which is to verify the "next" marking 1551 // information at the end of remark. 1552 // Currently there is only one place where this is called with 1553 // vo == UseMarkWord, which is to verify the marking during a 1554 // full GC. 1555 void verify(bool silent, VerifyOption vo); 1556 1557 // Override; it uses the "prev" marking information 1558 virtual void verify(bool silent); 1559 1560 // The methods below are here for convenience and dispatch the 1561 // appropriate method depending on value of the given VerifyOption 1562 // parameter. The values for that parameter, and their meanings, 1563 // are the same as those above. 1564 1565 bool is_obj_dead_cond(const oop obj, 1566 const HeapRegion* hr, 1567 const VerifyOption vo) const; 1568 1569 bool is_obj_dead_cond(const oop obj, 1570 const VerifyOption vo) const; 1571 1572 G1HeapSummary create_g1_heap_summary(); 1573 1574 // Printing 1575 1576 virtual void print_on(outputStream* st) const; 1577 virtual void print_extended_on(outputStream* st) const; 1578 virtual void print_on_error(outputStream* st) const; 1579 1580 virtual void print_gc_threads_on(outputStream* st) const; 1581 virtual void gc_threads_do(ThreadClosure* tc) const; 1582 1583 // Override 1584 void print_tracing_info() const; 1585 1586 // The following two methods are helpful for debugging RSet issues. 1587 void print_cset_rsets() PRODUCT_RETURN; 1588 void print_all_rsets() PRODUCT_RETURN; 1589 1590 public: 1591 size_t pending_card_num(); 1592 size_t cards_scanned(); 1593 1594 protected: 1595 size_t _max_heap_capacity; 1596 }; 1597 1598 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP