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/g1BiasedArray.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1HRPrinter.hpp" 34 #include "gc/g1/g1InCSetState.hpp" 35 #include "gc/g1/g1MonitoringSupport.hpp" 36 #include "gc/g1/g1EvacStats.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 "gc/shared/plab.hpp" 45 #include "memory/memRegion.hpp" 46 #include "utilities/stack.hpp" 47 48 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 49 // It uses the "Garbage First" heap organization and algorithm, which 50 // may combine concurrent marking with parallel, incremental compaction of 51 // heap subsets that will yield large amounts of garbage. 52 53 // Forward declarations 54 class HeapRegion; 55 class HRRSCleanupTask; 56 class GenerationSpec; 57 class OopsInHeapRegionClosure; 58 class G1ParScanThreadState; 59 class G1KlassScanClosure; 60 class G1ParScanThreadState; 61 class ObjectClosure; 62 class SpaceClosure; 63 class CompactibleSpaceClosure; 64 class Space; 65 class G1CollectorPolicy; 66 class GenRemSet; 67 class G1RemSet; 68 class HeapRegionRemSetIterator; 69 class ConcurrentMark; 70 class ConcurrentMarkThread; 71 class ConcurrentG1Refine; 72 class ConcurrentGCTimer; 73 class GenerationCounters; 74 class STWGCTimer; 75 class G1NewTracer; 76 class G1OldTracer; 77 class EvacuationFailedInfo; 78 class nmethod; 79 class Ticks; 80 class FlexibleWorkGang; 81 class G1Allocator; 82 class G1ArchiveAllocator; 83 84 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 85 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 86 87 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 88 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 89 90 class YoungList : public CHeapObj<mtGC> { 91 private: 92 G1CollectedHeap* _g1h; 93 94 HeapRegion* _head; 95 96 HeapRegion* _survivor_head; 97 HeapRegion* _survivor_tail; 98 99 HeapRegion* _curr; 100 101 uint _length; 102 uint _survivor_length; 103 104 size_t _last_sampled_rs_lengths; 105 size_t _sampled_rs_lengths; 106 107 void empty_list(HeapRegion* list); 108 109 public: 110 YoungList(G1CollectedHeap* g1h); 111 112 void push_region(HeapRegion* hr); 113 void add_survivor_region(HeapRegion* hr); 114 115 void empty_list(); 116 bool is_empty() { return _length == 0; } 117 uint length() { return _length; } 118 uint eden_length() { return length() - survivor_length(); } 119 uint survivor_length() { return _survivor_length; } 120 121 // Currently we do not keep track of the used byte sum for the 122 // young list and the survivors and it'd be quite a lot of work to 123 // do so. When we'll eventually replace the young list with 124 // instances of HeapRegionLinkedList we'll get that for free. So, 125 // we'll report the more accurate information then. 126 size_t eden_used_bytes() { 127 assert(length() >= survivor_length(), "invariant"); 128 return (size_t) eden_length() * HeapRegion::GrainBytes; 129 } 130 size_t survivor_used_bytes() { 131 return (size_t) survivor_length() * HeapRegion::GrainBytes; 132 } 133 134 void rs_length_sampling_init(); 135 bool rs_length_sampling_more(); 136 void rs_length_sampling_next(); 137 138 void reset_sampled_info() { 139 _last_sampled_rs_lengths = 0; 140 } 141 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 142 143 // for development purposes 144 void reset_auxilary_lists(); 145 void clear() { _head = NULL; _length = 0; } 146 147 void clear_survivors() { 148 _survivor_head = NULL; 149 _survivor_tail = NULL; 150 _survivor_length = 0; 151 } 152 153 HeapRegion* first_region() { return _head; } 154 HeapRegion* first_survivor_region() { return _survivor_head; } 155 HeapRegion* last_survivor_region() { return _survivor_tail; } 156 157 // debugging 158 bool check_list_well_formed(); 159 bool check_list_empty(bool check_sample = true); 160 void print(); 161 }; 162 163 // The G1 STW is alive closure. 164 // An instance is embedded into the G1CH and used as the 165 // (optional) _is_alive_non_header closure in the STW 166 // reference processor. It is also extensively used during 167 // reference processing during STW evacuation pauses. 168 class G1STWIsAliveClosure: public BoolObjectClosure { 169 G1CollectedHeap* _g1; 170 public: 171 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 172 bool do_object_b(oop p); 173 }; 174 175 class RefineCardTableEntryClosure; 176 177 class G1RegionMappingChangedListener : public G1MappingChangedListener { 178 private: 179 void reset_from_card_cache(uint start_idx, size_t num_regions); 180 public: 181 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 182 }; 183 184 class G1CollectedHeap : public CollectedHeap { 185 friend class VM_CollectForMetadataAllocation; 186 friend class VM_G1CollectForAllocation; 187 friend class VM_G1CollectFull; 188 friend class VM_G1IncCollectionPause; 189 friend class VMStructs; 190 friend class MutatorAllocRegion; 191 friend class G1GCAllocRegion; 192 193 // Closures used in implementation. 194 friend class G1ParScanThreadState; 195 friend class G1ParTask; 196 friend class G1PLABAllocator; 197 friend class G1PrepareCompactClosure; 198 199 // Other related classes. 200 friend class HeapRegionClaimer; 201 202 // Testing classes. 203 friend class G1CheckCSetFastTableClosure; 204 205 private: 206 FlexibleWorkGang* _workers; 207 208 static size_t _humongous_object_threshold_in_words; 209 210 // The secondary free list which contains regions that have been 211 // freed up during the cleanup process. This will be appended to 212 // the master free list when appropriate. 213 FreeRegionList _secondary_free_list; 214 215 // It keeps track of the old regions. 216 HeapRegionSet _old_set; 217 218 // It keeps track of the humongous regions. 219 HeapRegionSet _humongous_set; 220 221 void eagerly_reclaim_humongous_regions(); 222 223 // The number of regions we could create by expansion. 224 uint _expansion_regions; 225 226 // The block offset table for the G1 heap. 227 G1BlockOffsetSharedArray* _bot_shared; 228 229 // Tears down the region sets / lists so that they are empty and the 230 // regions on the heap do not belong to a region set / list. The 231 // only exception is the humongous set which we leave unaltered. If 232 // free_list_only is true, it will only tear down the master free 233 // list. It is called before a Full GC (free_list_only == false) or 234 // before heap shrinking (free_list_only == true). 235 void tear_down_region_sets(bool free_list_only); 236 237 // Rebuilds the region sets / lists so that they are repopulated to 238 // reflect the contents of the heap. The only exception is the 239 // humongous set which was not torn down in the first place. If 240 // free_list_only is true, it will only rebuild the master free 241 // list. It is called after a Full GC (free_list_only == false) or 242 // after heap shrinking (free_list_only == true). 243 void rebuild_region_sets(bool free_list_only); 244 245 // Callback for region mapping changed events. 246 G1RegionMappingChangedListener _listener; 247 248 // The sequence of all heap regions in the heap. 249 HeapRegionManager _hrm; 250 251 // Manages all allocations with regions except humongous object allocations. 252 G1Allocator* _allocator; 253 254 // Outside of GC pauses, the number of bytes used in all regions other 255 // than the current allocation region(s). 256 size_t _summary_bytes_used; 257 258 void increase_used(size_t bytes); 259 void decrease_used(size_t bytes); 260 261 void set_used(size_t bytes); 262 263 // Class that handles archive allocation ranges. 264 G1ArchiveAllocator* _archive_allocator; 265 266 // Statistics for each allocation context 267 AllocationContextStats _allocation_context_stats; 268 269 // GC allocation statistics policy for survivors. 270 G1EvacStats _survivor_evac_stats; 271 272 // GC allocation statistics policy for tenured objects. 273 G1EvacStats _old_evac_stats; 274 275 // It specifies whether we should attempt to expand the heap after a 276 // region allocation failure. If heap expansion fails we set this to 277 // false so that we don't re-attempt the heap expansion (it's likely 278 // that subsequent expansion attempts will also fail if one fails). 279 // Currently, it is only consulted during GC and it's reset at the 280 // start of each GC. 281 bool _expand_heap_after_alloc_failure; 282 283 // Helper for monitoring and management support. 284 G1MonitoringSupport* _g1mm; 285 286 // Records whether the region at the given index is (still) a 287 // candidate for eager reclaim. Only valid for humongous start 288 // regions; other regions have unspecified values. Humongous start 289 // regions are initialized at start of collection pause, with 290 // candidates removed from the set as they are found reachable from 291 // roots or the young generation. 292 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 293 protected: 294 bool default_value() const { return false; } 295 public: 296 void clear() { G1BiasedMappedArray<bool>::clear(); } 297 void set_candidate(uint region, bool value) { 298 set_by_index(region, value); 299 } 300 bool is_candidate(uint region) { 301 return get_by_index(region); 302 } 303 }; 304 305 HumongousReclaimCandidates _humongous_reclaim_candidates; 306 // Stores whether during humongous object registration we found candidate regions. 307 // If not, we can skip a few steps. 308 bool _has_humongous_reclaim_candidates; 309 310 volatile unsigned _gc_time_stamp; 311 312 size_t* _surviving_young_words; 313 314 G1HRPrinter _hr_printer; 315 316 void setup_surviving_young_words(); 317 void update_surviving_young_words(size_t* surv_young_words); 318 void cleanup_surviving_young_words(); 319 320 // It decides whether an explicit GC should start a concurrent cycle 321 // instead of doing a STW GC. Currently, a concurrent cycle is 322 // explicitly started if: 323 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 324 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 325 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 326 // (d) cause == _g1_humongous_allocation 327 bool should_do_concurrent_full_gc(GCCause::Cause cause); 328 329 // indicates whether we are in young or mixed GC mode 330 G1CollectorState _collector_state; 331 332 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 333 // concurrent cycles) we have started. 334 volatile uint _old_marking_cycles_started; 335 336 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 337 // concurrent cycles) we have completed. 338 volatile uint _old_marking_cycles_completed; 339 340 bool _heap_summary_sent; 341 342 // This is a non-product method that is helpful for testing. It is 343 // called at the end of a GC and artificially expands the heap by 344 // allocating a number of dead regions. This way we can induce very 345 // frequent marking cycles and stress the cleanup / concurrent 346 // cleanup code more (as all the regions that will be allocated by 347 // this method will be found dead by the marking cycle). 348 void allocate_dummy_regions() PRODUCT_RETURN; 349 350 // Clear RSets after a compaction. It also resets the GC time stamps. 351 void clear_rsets_post_compaction(); 352 353 // If the HR printer is active, dump the state of the regions in the 354 // heap after a compaction. 355 void print_hrm_post_compaction(); 356 357 // Create a memory mapper for auxiliary data structures of the given size and 358 // translation factor. 359 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 360 size_t size, 361 size_t translation_factor); 362 363 double verify(bool guard, const char* msg); 364 void verify_before_gc(); 365 void verify_after_gc(); 366 367 void log_gc_header(); 368 void log_gc_footer(double pause_time_sec); 369 370 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 371 372 // These are macros so that, if the assert fires, we get the correct 373 // line number, file, etc. 374 375 #define heap_locking_asserts_err_msg(_extra_message_) \ 376 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 377 (_extra_message_), \ 378 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 379 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 380 BOOL_TO_STR(Thread::current()->is_VM_thread())) 381 382 #define assert_heap_locked() \ 383 do { \ 384 assert(Heap_lock->owned_by_self(), \ 385 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 386 } while (0) 387 388 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 389 do { \ 390 assert(Heap_lock->owned_by_self() || \ 391 (SafepointSynchronize::is_at_safepoint() && \ 392 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 393 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 394 "should be at a safepoint")); \ 395 } while (0) 396 397 #define assert_heap_locked_and_not_at_safepoint() \ 398 do { \ 399 assert(Heap_lock->owned_by_self() && \ 400 !SafepointSynchronize::is_at_safepoint(), \ 401 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 402 "should not be at a safepoint")); \ 403 } while (0) 404 405 #define assert_heap_not_locked() \ 406 do { \ 407 assert(!Heap_lock->owned_by_self(), \ 408 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 409 } while (0) 410 411 #define assert_heap_not_locked_and_not_at_safepoint() \ 412 do { \ 413 assert(!Heap_lock->owned_by_self() && \ 414 !SafepointSynchronize::is_at_safepoint(), \ 415 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 416 "should not be at a safepoint")); \ 417 } while (0) 418 419 #define assert_at_safepoint(_should_be_vm_thread_) \ 420 do { \ 421 assert(SafepointSynchronize::is_at_safepoint() && \ 422 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 423 heap_locking_asserts_err_msg("should be at a safepoint")); \ 424 } while (0) 425 426 #define assert_not_at_safepoint() \ 427 do { \ 428 assert(!SafepointSynchronize::is_at_safepoint(), \ 429 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 430 } while (0) 431 432 protected: 433 434 // The young region list. 435 YoungList* _young_list; 436 437 // The current policy object for the collector. 438 G1CollectorPolicy* _g1_policy; 439 440 // This is the second level of trying to allocate a new region. If 441 // new_region() didn't find a region on the free_list, this call will 442 // check whether there's anything available on the 443 // secondary_free_list and/or wait for more regions to appear on 444 // that list, if _free_regions_coming is set. 445 HeapRegion* new_region_try_secondary_free_list(bool is_old); 446 447 // Try to allocate a single non-humongous HeapRegion sufficient for 448 // an allocation of the given word_size. If do_expand is true, 449 // attempt to expand the heap if necessary to satisfy the allocation 450 // request. If the region is to be used as an old region or for a 451 // humongous object, set is_old to true. If not, to false. 452 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 453 454 // Initialize a contiguous set of free regions of length num_regions 455 // and starting at index first so that they appear as a single 456 // humongous region. 457 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 458 uint num_regions, 459 size_t word_size, 460 AllocationContext_t context); 461 462 // Attempt to allocate a humongous object of the given size. Return 463 // NULL if unsuccessful. 464 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 465 466 // The following two methods, allocate_new_tlab() and 467 // mem_allocate(), are the two main entry points from the runtime 468 // into the G1's allocation routines. They have the following 469 // assumptions: 470 // 471 // * They should both be called outside safepoints. 472 // 473 // * They should both be called without holding the Heap_lock. 474 // 475 // * All allocation requests for new TLABs should go to 476 // allocate_new_tlab(). 477 // 478 // * All non-TLAB allocation requests should go to mem_allocate(). 479 // 480 // * If either call cannot satisfy the allocation request using the 481 // current allocating region, they will try to get a new one. If 482 // this fails, they will attempt to do an evacuation pause and 483 // retry the allocation. 484 // 485 // * If all allocation attempts fail, even after trying to schedule 486 // an evacuation pause, allocate_new_tlab() will return NULL, 487 // whereas mem_allocate() will attempt a heap expansion and/or 488 // schedule a Full GC. 489 // 490 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 491 // should never be called with word_size being humongous. All 492 // humongous allocation requests should go to mem_allocate() which 493 // will satisfy them with a special path. 494 495 virtual HeapWord* allocate_new_tlab(size_t word_size); 496 497 virtual HeapWord* mem_allocate(size_t word_size, 498 bool* gc_overhead_limit_was_exceeded); 499 500 // The following three methods take a gc_count_before_ret 501 // parameter which is used to return the GC count if the method 502 // returns NULL. Given that we are required to read the GC count 503 // while holding the Heap_lock, and these paths will take the 504 // Heap_lock at some point, it's easier to get them to read the GC 505 // count while holding the Heap_lock before they return NULL instead 506 // of the caller (namely: mem_allocate()) having to also take the 507 // Heap_lock just to read the GC count. 508 509 // First-level mutator allocation attempt: try to allocate out of 510 // the mutator alloc region without taking the Heap_lock. This 511 // should only be used for non-humongous allocations. 512 inline HeapWord* attempt_allocation(size_t word_size, 513 uint* gc_count_before_ret, 514 uint* gclocker_retry_count_ret); 515 516 // Second-level mutator allocation attempt: take the Heap_lock and 517 // retry the allocation attempt, potentially scheduling a GC 518 // pause. This should only be used for non-humongous allocations. 519 HeapWord* attempt_allocation_slow(size_t word_size, 520 AllocationContext_t context, 521 uint* gc_count_before_ret, 522 uint* gclocker_retry_count_ret); 523 524 // Takes the Heap_lock and attempts a humongous allocation. It can 525 // potentially schedule a GC pause. 526 HeapWord* attempt_allocation_humongous(size_t word_size, 527 uint* gc_count_before_ret, 528 uint* gclocker_retry_count_ret); 529 530 // Allocation attempt that should be called during safepoints (e.g., 531 // at the end of a successful GC). expect_null_mutator_alloc_region 532 // specifies whether the mutator alloc region is expected to be NULL 533 // or not. 534 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 535 AllocationContext_t context, 536 bool expect_null_mutator_alloc_region); 537 538 // These methods are the "callbacks" from the G1AllocRegion class. 539 540 // For mutator alloc regions. 541 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 542 void retire_mutator_alloc_region(HeapRegion* alloc_region, 543 size_t allocated_bytes); 544 545 // For GC alloc regions. 546 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 547 InCSetState dest); 548 void retire_gc_alloc_region(HeapRegion* alloc_region, 549 size_t allocated_bytes, InCSetState dest); 550 551 // - if explicit_gc is true, the GC is for a System.gc() or a heap 552 // inspection request and should collect the entire heap 553 // - if clear_all_soft_refs is true, all soft references should be 554 // cleared during the GC 555 // - if explicit_gc is false, word_size describes the allocation that 556 // the GC should attempt (at least) to satisfy 557 // - it returns false if it is unable to do the collection due to the 558 // GC locker being active, true otherwise 559 bool do_collection(bool explicit_gc, 560 bool clear_all_soft_refs, 561 size_t word_size); 562 563 // Callback from VM_G1CollectFull operation. 564 // Perform a full collection. 565 virtual void do_full_collection(bool clear_all_soft_refs); 566 567 // Resize the heap if necessary after a full collection. If this is 568 // after a collect-for allocation, "word_size" is the allocation size, 569 // and will be considered part of the used portion of the heap. 570 void resize_if_necessary_after_full_collection(size_t word_size); 571 572 // Callback from VM_G1CollectForAllocation operation. 573 // This function does everything necessary/possible to satisfy a 574 // failed allocation request (including collection, expansion, etc.) 575 HeapWord* satisfy_failed_allocation(size_t word_size, 576 AllocationContext_t context, 577 bool* succeeded); 578 579 // Attempting to expand the heap sufficiently 580 // to support an allocation of the given "word_size". If 581 // successful, perform the allocation and return the address of the 582 // allocated block, or else "NULL". 583 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 584 585 // Process any reference objects discovered during 586 // an incremental evacuation pause. 587 void process_discovered_references(G1ParScanThreadState** per_thread_states); 588 589 // Enqueue any remaining discovered references 590 // after processing. 591 void enqueue_discovered_references(G1ParScanThreadState** per_thread_states); 592 593 public: 594 FlexibleWorkGang* workers() const { return _workers; } 595 596 G1Allocator* allocator() { 597 return _allocator; 598 } 599 600 G1MonitoringSupport* g1mm() { 601 assert(_g1mm != NULL, "should have been initialized"); 602 return _g1mm; 603 } 604 605 // Expand the garbage-first heap by at least the given size (in bytes!). 606 // Returns true if the heap was expanded by the requested amount; 607 // false otherwise. 608 // (Rounds up to a HeapRegion boundary.) 609 bool expand(size_t expand_bytes); 610 611 // Returns the PLAB statistics for a given destination. 612 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 613 614 // Determines PLAB size for a given destination. 615 inline size_t desired_plab_sz(InCSetState dest); 616 617 inline AllocationContextStats& allocation_context_stats(); 618 619 // Do anything common to GC's. 620 void gc_prologue(bool full); 621 void gc_epilogue(bool full); 622 623 // Modify the reclaim candidate set and test for presence. 624 // These are only valid for starts_humongous regions. 625 inline void set_humongous_reclaim_candidate(uint region, bool value); 626 inline bool is_humongous_reclaim_candidate(uint region); 627 628 // Remove from the reclaim candidate set. Also remove from the 629 // collection set so that later encounters avoid the slow path. 630 inline void set_humongous_is_live(oop obj); 631 632 // Register the given region to be part of the collection set. 633 inline void register_humongous_region_with_cset(uint index); 634 // Register regions with humongous objects (actually on the start region) in 635 // the in_cset_fast_test table. 636 void register_humongous_regions_with_cset(); 637 // We register a region with the fast "in collection set" test. We 638 // simply set to true the array slot corresponding to this region. 639 void register_young_region_with_cset(HeapRegion* r) { 640 _in_cset_fast_test.set_in_young(r->hrm_index()); 641 } 642 void register_old_region_with_cset(HeapRegion* r) { 643 _in_cset_fast_test.set_in_old(r->hrm_index()); 644 } 645 void clear_in_cset(const HeapRegion* hr) { 646 _in_cset_fast_test.clear(hr); 647 } 648 649 void clear_cset_fast_test() { 650 _in_cset_fast_test.clear(); 651 } 652 653 // This is called at the start of either a concurrent cycle or a Full 654 // GC to update the number of old marking cycles started. 655 void increment_old_marking_cycles_started(); 656 657 // This is called at the end of either a concurrent cycle or a Full 658 // GC to update the number of old marking cycles completed. Those two 659 // can happen in a nested fashion, i.e., we start a concurrent 660 // cycle, a Full GC happens half-way through it which ends first, 661 // and then the cycle notices that a Full GC happened and ends 662 // too. The concurrent parameter is a boolean to help us do a bit 663 // tighter consistency checking in the method. If concurrent is 664 // false, the caller is the inner caller in the nesting (i.e., the 665 // Full GC). If concurrent is true, the caller is the outer caller 666 // in this nesting (i.e., the concurrent cycle). Further nesting is 667 // not currently supported. The end of this call also notifies 668 // the FullGCCount_lock in case a Java thread is waiting for a full 669 // GC to happen (e.g., it called System.gc() with 670 // +ExplicitGCInvokesConcurrent). 671 void increment_old_marking_cycles_completed(bool concurrent); 672 673 uint old_marking_cycles_completed() { 674 return _old_marking_cycles_completed; 675 } 676 677 void register_concurrent_cycle_start(const Ticks& start_time); 678 void register_concurrent_cycle_end(); 679 void trace_heap_after_concurrent_cycle(); 680 681 G1HRPrinter* hr_printer() { return &_hr_printer; } 682 683 // Allocates a new heap region instance. 684 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 685 686 // Allocates a new per thread par scan state for the given thread id. 687 G1ParScanThreadState* new_par_scan_state(uint worker_id); 688 689 // Allocate the highest free region in the reserved heap. This will commit 690 // regions as necessary. 691 HeapRegion* alloc_highest_free_region(); 692 693 // Frees a non-humongous region by initializing its contents and 694 // adding it to the free list that's passed as a parameter (this is 695 // usually a local list which will be appended to the master free 696 // list later). The used bytes of freed regions are accumulated in 697 // pre_used. If par is true, the region's RSet will not be freed 698 // up. The assumption is that this will be done later. 699 // The locked parameter indicates if the caller has already taken 700 // care of proper synchronization. This may allow some optimizations. 701 void free_region(HeapRegion* hr, 702 FreeRegionList* free_list, 703 bool par, 704 bool locked = false); 705 706 // It dirties the cards that cover the block so that the post 707 // write barrier never queues anything when updating objects on this 708 // block. It is assumed (and in fact we assert) that the block 709 // belongs to a young region. 710 inline void dirty_young_block(HeapWord* start, size_t word_size); 711 712 // Frees a humongous region by collapsing it into individual regions 713 // and calling free_region() for each of them. The freed regions 714 // will be added to the free list that's passed as a parameter (this 715 // is usually a local list which will be appended to the master free 716 // list later). The used bytes of freed regions are accumulated in 717 // pre_used. If par is true, the region's RSet will not be freed 718 // up. The assumption is that this will be done later. 719 void free_humongous_region(HeapRegion* hr, 720 FreeRegionList* free_list, 721 bool par); 722 723 // Facility for allocating in 'archive' regions in high heap memory and 724 // recording the allocated ranges. These should all be called from the 725 // VM thread at safepoints, without the heap lock held. They can be used 726 // to create and archive a set of heap regions which can be mapped at the 727 // same fixed addresses in a subsequent JVM invocation. 728 void begin_archive_alloc_range(); 729 730 // Check if the requested size would be too large for an archive allocation. 731 bool is_archive_alloc_too_large(size_t word_size); 732 733 // Allocate memory of the requested size from the archive region. This will 734 // return NULL if the size is too large or if no memory is available. It 735 // does not trigger a garbage collection. 736 HeapWord* archive_mem_allocate(size_t word_size); 737 738 // Optionally aligns the end address and returns the allocated ranges in 739 // an array of MemRegions in order of ascending addresses. 740 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 741 size_t end_alignment_in_bytes = 0); 742 743 // Facility for allocating a fixed range within the heap and marking 744 // the containing regions as 'archive'. For use at JVM init time, when the 745 // caller may mmap archived heap data at the specified range(s). 746 // Verify that the MemRegions specified in the argument array are within the 747 // reserved heap. 748 bool check_archive_addresses(MemRegion* range, size_t count); 749 750 // Commit the appropriate G1 regions containing the specified MemRegions 751 // and mark them as 'archive' regions. The regions in the array must be 752 // non-overlapping and in order of ascending address. 753 bool alloc_archive_regions(MemRegion* range, size_t count); 754 755 // Insert any required filler objects in the G1 regions around the specified 756 // ranges to make the regions parseable. This must be called after 757 // alloc_archive_regions, and after class loading has occurred. 758 void fill_archive_regions(MemRegion* range, size_t count); 759 760 protected: 761 762 // Shrink the garbage-first heap by at most the given size (in bytes!). 763 // (Rounds down to a HeapRegion boundary.) 764 virtual void shrink(size_t expand_bytes); 765 void shrink_helper(size_t expand_bytes); 766 767 #if TASKQUEUE_STATS 768 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 769 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 770 void reset_taskqueue_stats(); 771 #endif // TASKQUEUE_STATS 772 773 // Schedule the VM operation that will do an evacuation pause to 774 // satisfy an allocation request of word_size. *succeeded will 775 // return whether the VM operation was successful (it did do an 776 // evacuation pause) or not (another thread beat us to it or the GC 777 // locker was active). Given that we should not be holding the 778 // Heap_lock when we enter this method, we will pass the 779 // gc_count_before (i.e., total_collections()) as a parameter since 780 // it has to be read while holding the Heap_lock. Currently, both 781 // methods that call do_collection_pause() release the Heap_lock 782 // before the call, so it's easy to read gc_count_before just before. 783 HeapWord* do_collection_pause(size_t word_size, 784 uint gc_count_before, 785 bool* succeeded, 786 GCCause::Cause gc_cause); 787 788 void wait_for_root_region_scanning(); 789 790 // The guts of the incremental collection pause, executed by the vm 791 // thread. It returns false if it is unable to do the collection due 792 // to the GC locker being active, true otherwise 793 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 794 795 // Actually do the work of evacuating the collection set. 796 void evacuate_collection_set(EvacuationInfo& evacuation_info); 797 798 // Print the header for the per-thread termination statistics. 799 static void print_termination_stats_hdr(outputStream* const st); 800 // Print actual per-thread termination statistics. 801 void print_termination_stats(outputStream* const st, 802 uint worker_id, 803 double elapsed_ms, 804 double strong_roots_ms, 805 double term_ms, 806 size_t term_attempts, 807 size_t alloc_buffer_waste, 808 size_t undo_waste) const; 809 // Update object copying statistics. 810 void record_obj_copy_mem_stats(); 811 812 // The g1 remembered set of the heap. 813 G1RemSet* _g1_rem_set; 814 815 // A set of cards that cover the objects for which the Rsets should be updated 816 // concurrently after the collection. 817 DirtyCardQueueSet _dirty_card_queue_set; 818 819 // The closure used to refine a single card. 820 RefineCardTableEntryClosure* _refine_cte_cl; 821 822 // A DirtyCardQueueSet that is used to hold cards that contain 823 // references into the current collection set. This is used to 824 // update the remembered sets of the regions in the collection 825 // set in the event of an evacuation failure. 826 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 827 828 // After a collection pause, make the regions in the CS into free 829 // regions. 830 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 831 832 // Abandon the current collection set without recording policy 833 // statistics or updating free lists. 834 void abandon_collection_set(HeapRegion* cs_head); 835 836 // The concurrent marker (and the thread it runs in.) 837 ConcurrentMark* _cm; 838 ConcurrentMarkThread* _cmThread; 839 840 // The concurrent refiner. 841 ConcurrentG1Refine* _cg1r; 842 843 // The parallel task queues 844 RefToScanQueueSet *_task_queues; 845 846 // True iff a evacuation has failed in the current collection. 847 bool _evacuation_failed; 848 849 EvacuationFailedInfo* _evacuation_failed_info_array; 850 851 // Failed evacuations cause some logical from-space objects to have 852 // forwarding pointers to themselves. Reset them. 853 void remove_self_forwarding_pointers(); 854 855 struct OopAndMarkOop { 856 private: 857 oop _o; 858 markOop _m; 859 public: 860 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { 861 } 862 863 void set_mark() { 864 _o->set_mark(_m); 865 } 866 }; 867 868 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack; 869 // Stores marks with the corresponding oop that we need to preserve during evacuation 870 // failure. 871 OopAndMarkOopStack* _preserved_objs; 872 873 // Preserve the mark of "obj", if necessary, in preparation for its mark 874 // word being overwritten with a self-forwarding-pointer. 875 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 876 877 #ifndef PRODUCT 878 // Support for forcing evacuation failures. Analogous to 879 // PromotionFailureALot for the other collectors. 880 881 // Records whether G1EvacuationFailureALot should be in effect 882 // for the current GC 883 bool _evacuation_failure_alot_for_current_gc; 884 885 // Used to record the GC number for interval checking when 886 // determining whether G1EvaucationFailureALot is in effect 887 // for the current GC. 888 size_t _evacuation_failure_alot_gc_number; 889 890 // Count of the number of evacuations between failures. 891 volatile size_t _evacuation_failure_alot_count; 892 893 // Set whether G1EvacuationFailureALot should be in effect 894 // for the current GC (based upon the type of GC and which 895 // command line flags are set); 896 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 897 bool during_initial_mark, 898 bool during_marking); 899 900 inline void set_evacuation_failure_alot_for_current_gc(); 901 902 // Return true if it's time to cause an evacuation failure. 903 inline bool evacuation_should_fail(); 904 905 // Reset the G1EvacuationFailureALot counters. Should be called at 906 // the end of an evacuation pause in which an evacuation failure occurred. 907 inline void reset_evacuation_should_fail(); 908 #endif // !PRODUCT 909 910 // ("Weak") Reference processing support. 911 // 912 // G1 has 2 instances of the reference processor class. One 913 // (_ref_processor_cm) handles reference object discovery 914 // and subsequent processing during concurrent marking cycles. 915 // 916 // The other (_ref_processor_stw) handles reference object 917 // discovery and processing during full GCs and incremental 918 // evacuation pauses. 919 // 920 // During an incremental pause, reference discovery will be 921 // temporarily disabled for _ref_processor_cm and will be 922 // enabled for _ref_processor_stw. At the end of the evacuation 923 // pause references discovered by _ref_processor_stw will be 924 // processed and discovery will be disabled. The previous 925 // setting for reference object discovery for _ref_processor_cm 926 // will be re-instated. 927 // 928 // At the start of marking: 929 // * Discovery by the CM ref processor is verified to be inactive 930 // and it's discovered lists are empty. 931 // * Discovery by the CM ref processor is then enabled. 932 // 933 // At the end of marking: 934 // * Any references on the CM ref processor's discovered 935 // lists are processed (possibly MT). 936 // 937 // At the start of full GC we: 938 // * Disable discovery by the CM ref processor and 939 // empty CM ref processor's discovered lists 940 // (without processing any entries). 941 // * Verify that the STW ref processor is inactive and it's 942 // discovered lists are empty. 943 // * Temporarily set STW ref processor discovery as single threaded. 944 // * Temporarily clear the STW ref processor's _is_alive_non_header 945 // field. 946 // * Finally enable discovery by the STW ref processor. 947 // 948 // The STW ref processor is used to record any discovered 949 // references during the full GC. 950 // 951 // At the end of a full GC we: 952 // * Enqueue any reference objects discovered by the STW ref processor 953 // that have non-live referents. This has the side-effect of 954 // making the STW ref processor inactive by disabling discovery. 955 // * Verify that the CM ref processor is still inactive 956 // and no references have been placed on it's discovered 957 // lists (also checked as a precondition during initial marking). 958 959 // The (stw) reference processor... 960 ReferenceProcessor* _ref_processor_stw; 961 962 STWGCTimer* _gc_timer_stw; 963 ConcurrentGCTimer* _gc_timer_cm; 964 965 G1OldTracer* _gc_tracer_cm; 966 G1NewTracer* _gc_tracer_stw; 967 968 // During reference object discovery, the _is_alive_non_header 969 // closure (if non-null) is applied to the referent object to 970 // determine whether the referent is live. If so then the 971 // reference object does not need to be 'discovered' and can 972 // be treated as a regular oop. This has the benefit of reducing 973 // the number of 'discovered' reference objects that need to 974 // be processed. 975 // 976 // Instance of the is_alive closure for embedding into the 977 // STW reference processor as the _is_alive_non_header field. 978 // Supplying a value for the _is_alive_non_header field is 979 // optional but doing so prevents unnecessary additions to 980 // the discovered lists during reference discovery. 981 G1STWIsAliveClosure _is_alive_closure_stw; 982 983 // The (concurrent marking) reference processor... 984 ReferenceProcessor* _ref_processor_cm; 985 986 // Instance of the concurrent mark is_alive closure for embedding 987 // into the Concurrent Marking reference processor as the 988 // _is_alive_non_header field. Supplying a value for the 989 // _is_alive_non_header field is optional but doing so prevents 990 // unnecessary additions to the discovered lists during reference 991 // discovery. 992 G1CMIsAliveClosure _is_alive_closure_cm; 993 994 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 995 HeapRegion** _worker_cset_start_region; 996 997 // Time stamp to validate the regions recorded in the cache 998 // used by G1CollectedHeap::start_cset_region_for_worker(). 999 // The heap region entry for a given worker is valid iff 1000 // the associated time stamp value matches the current value 1001 // of G1CollectedHeap::_gc_time_stamp. 1002 uint* _worker_cset_start_region_time_stamp; 1003 1004 volatile bool _free_regions_coming; 1005 1006 public: 1007 1008 void set_refine_cte_cl_concurrency(bool concurrent); 1009 1010 RefToScanQueue *task_queue(uint i) const; 1011 1012 uint num_task_queues() const; 1013 1014 // A set of cards where updates happened during the GC 1015 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1016 1017 // A DirtyCardQueueSet that is used to hold cards that contain 1018 // references into the current collection set. This is used to 1019 // update the remembered sets of the regions in the collection 1020 // set in the event of an evacuation failure. 1021 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1022 { return _into_cset_dirty_card_queue_set; } 1023 1024 // Create a G1CollectedHeap with the specified policy. 1025 // Must call the initialize method afterwards. 1026 // May not return if something goes wrong. 1027 G1CollectedHeap(G1CollectorPolicy* policy); 1028 1029 // Initialize the G1CollectedHeap to have the initial and 1030 // maximum sizes and remembered and barrier sets 1031 // specified by the policy object. 1032 jint initialize(); 1033 1034 virtual void stop(); 1035 1036 // Return the (conservative) maximum heap alignment for any G1 heap 1037 static size_t conservative_max_heap_alignment(); 1038 1039 // Does operations required after initialization has been done. 1040 void post_initialize(); 1041 1042 // Initialize weak reference processing. 1043 void ref_processing_init(); 1044 1045 virtual Name kind() const { 1046 return CollectedHeap::G1CollectedHeap; 1047 } 1048 1049 G1CollectorState* collector_state() { return &_collector_state; } 1050 1051 // The current policy object for the collector. 1052 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1053 1054 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1055 1056 // Adaptive size policy. No such thing for g1. 1057 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1058 1059 // The rem set and barrier set. 1060 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1061 1062 unsigned get_gc_time_stamp() { 1063 return _gc_time_stamp; 1064 } 1065 1066 inline void reset_gc_time_stamp(); 1067 1068 void check_gc_time_stamps() PRODUCT_RETURN; 1069 1070 inline void increment_gc_time_stamp(); 1071 1072 // Reset the given region's GC timestamp. If it's starts humongous, 1073 // also reset the GC timestamp of its corresponding 1074 // continues humongous regions too. 1075 void reset_gc_time_stamps(HeapRegion* hr); 1076 1077 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1078 DirtyCardQueue* into_cset_dcq, 1079 bool concurrent, uint worker_i); 1080 1081 // The shared block offset table array. 1082 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1083 1084 // Reference Processing accessors 1085 1086 // The STW reference processor.... 1087 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1088 1089 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1090 1091 // The Concurrent Marking reference processor... 1092 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1093 1094 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1095 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1096 1097 virtual size_t capacity() const; 1098 virtual size_t used() const; 1099 // This should be called when we're not holding the heap lock. The 1100 // result might be a bit inaccurate. 1101 size_t used_unlocked() const; 1102 size_t recalculate_used() const; 1103 1104 // These virtual functions do the actual allocation. 1105 // Some heaps may offer a contiguous region for shared non-blocking 1106 // allocation, via inlined code (by exporting the address of the top and 1107 // end fields defining the extent of the contiguous allocation region.) 1108 // But G1CollectedHeap doesn't yet support this. 1109 1110 virtual bool is_maximal_no_gc() const { 1111 return _hrm.available() == 0; 1112 } 1113 1114 // The current number of regions in the heap. 1115 uint num_regions() const { return _hrm.length(); } 1116 1117 // The max number of regions in the heap. 1118 uint max_regions() const { return _hrm.max_length(); } 1119 1120 // The number of regions that are completely free. 1121 uint num_free_regions() const { return _hrm.num_free_regions(); } 1122 1123 MemoryUsage get_auxiliary_data_memory_usage() const { 1124 return _hrm.get_auxiliary_data_memory_usage(); 1125 } 1126 1127 // The number of regions that are not completely free. 1128 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1129 1130 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1131 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1132 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1133 void verify_dirty_young_regions() PRODUCT_RETURN; 1134 1135 #ifndef PRODUCT 1136 // Make sure that the given bitmap has no marked objects in the 1137 // range [from,limit). If it does, print an error message and return 1138 // false. Otherwise, just return true. bitmap_name should be "prev" 1139 // or "next". 1140 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1141 HeapWord* from, HeapWord* limit); 1142 1143 // Verify that the prev / next bitmap range [tams,end) for the given 1144 // region has no marks. Return true if all is well, false if errors 1145 // are detected. 1146 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1147 #endif // PRODUCT 1148 1149 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1150 // the given region do not have any spurious marks. If errors are 1151 // detected, print appropriate error messages and crash. 1152 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1153 1154 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1155 // have any spurious marks. If errors are detected, print 1156 // appropriate error messages and crash. 1157 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1158 1159 // Do sanity check on the contents of the in-cset fast test table. 1160 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1161 1162 // verify_region_sets() performs verification over the region 1163 // lists. It will be compiled in the product code to be used when 1164 // necessary (i.e., during heap verification). 1165 void verify_region_sets(); 1166 1167 // verify_region_sets_optional() is planted in the code for 1168 // list verification in non-product builds (and it can be enabled in 1169 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1170 #if HEAP_REGION_SET_FORCE_VERIFY 1171 void verify_region_sets_optional() { 1172 verify_region_sets(); 1173 } 1174 #else // HEAP_REGION_SET_FORCE_VERIFY 1175 void verify_region_sets_optional() { } 1176 #endif // HEAP_REGION_SET_FORCE_VERIFY 1177 1178 #ifdef ASSERT 1179 bool is_on_master_free_list(HeapRegion* hr) { 1180 return _hrm.is_free(hr); 1181 } 1182 #endif // ASSERT 1183 1184 // Wrapper for the region list operations that can be called from 1185 // methods outside this class. 1186 1187 void secondary_free_list_add(FreeRegionList* list) { 1188 _secondary_free_list.add_ordered(list); 1189 } 1190 1191 void append_secondary_free_list() { 1192 _hrm.insert_list_into_free_list(&_secondary_free_list); 1193 } 1194 1195 void append_secondary_free_list_if_not_empty_with_lock() { 1196 // If the secondary free list looks empty there's no reason to 1197 // take the lock and then try to append it. 1198 if (!_secondary_free_list.is_empty()) { 1199 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1200 append_secondary_free_list(); 1201 } 1202 } 1203 1204 inline void old_set_add(HeapRegion* hr); 1205 inline void old_set_remove(HeapRegion* hr); 1206 1207 size_t non_young_capacity_bytes() { 1208 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1209 } 1210 1211 void set_free_regions_coming(); 1212 void reset_free_regions_coming(); 1213 bool free_regions_coming() { return _free_regions_coming; } 1214 void wait_while_free_regions_coming(); 1215 1216 // Determine whether the given region is one that we are using as an 1217 // old GC alloc region. 1218 bool is_old_gc_alloc_region(HeapRegion* hr); 1219 1220 // Perform a collection of the heap; intended for use in implementing 1221 // "System.gc". This probably implies as full a collection as the 1222 // "CollectedHeap" supports. 1223 virtual void collect(GCCause::Cause cause); 1224 1225 // The same as above but assume that the caller holds the Heap_lock. 1226 void collect_locked(GCCause::Cause cause); 1227 1228 virtual bool copy_allocation_context_stats(const jint* contexts, 1229 jlong* totals, 1230 jbyte* accuracy, 1231 jint len); 1232 1233 // True iff an evacuation has failed in the most-recent collection. 1234 bool evacuation_failed() { return _evacuation_failed; } 1235 1236 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1237 void prepend_to_freelist(FreeRegionList* list); 1238 void decrement_summary_bytes(size_t bytes); 1239 1240 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1241 virtual bool is_in(const void* p) const; 1242 #ifdef ASSERT 1243 // Returns whether p is in one of the available areas of the heap. Slow but 1244 // extensive version. 1245 bool is_in_exact(const void* p) const; 1246 #endif 1247 1248 // Return "TRUE" iff the given object address is within the collection 1249 // set. Slow implementation. 1250 bool obj_in_cs(oop obj); 1251 1252 inline bool is_in_cset(const HeapRegion *hr); 1253 inline bool is_in_cset(oop obj); 1254 1255 inline bool is_in_cset_or_humongous(const oop obj); 1256 1257 private: 1258 // This array is used for a quick test on whether a reference points into 1259 // the collection set or not. Each of the array's elements denotes whether the 1260 // corresponding region is in the collection set or not. 1261 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1262 1263 public: 1264 1265 inline InCSetState in_cset_state(const oop obj); 1266 1267 // Return "TRUE" iff the given object address is in the reserved 1268 // region of g1. 1269 bool is_in_g1_reserved(const void* p) const { 1270 return _hrm.reserved().contains(p); 1271 } 1272 1273 // Returns a MemRegion that corresponds to the space that has been 1274 // reserved for the heap 1275 MemRegion g1_reserved() const { 1276 return _hrm.reserved(); 1277 } 1278 1279 virtual bool is_in_closed_subset(const void* p) const; 1280 1281 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1282 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1283 } 1284 1285 // This resets the card table to all zeros. It is used after 1286 // a collection pause which used the card table to claim cards. 1287 void cleanUpCardTable(); 1288 1289 // Iteration functions. 1290 1291 // Iterate over all objects, calling "cl.do_object" on each. 1292 virtual void object_iterate(ObjectClosure* cl); 1293 1294 virtual void safe_object_iterate(ObjectClosure* cl) { 1295 object_iterate(cl); 1296 } 1297 1298 // Iterate over heap regions, in address order, terminating the 1299 // iteration early if the "doHeapRegion" method returns "true". 1300 void heap_region_iterate(HeapRegionClosure* blk) const; 1301 1302 // Return the region with the given index. It assumes the index is valid. 1303 inline HeapRegion* region_at(uint index) const; 1304 1305 // Calculate the region index of the given address. Given address must be 1306 // within the heap. 1307 inline uint addr_to_region(HeapWord* addr) const; 1308 1309 inline HeapWord* bottom_addr_for_region(uint index) const; 1310 1311 // Iterate over the heap regions in parallel. Assumes that this will be called 1312 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1313 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1314 // to each of the regions, by attempting to claim the region using the 1315 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1316 // region. The concurrent argument should be set to true if iteration is 1317 // performed concurrently, during which no assumptions are made for consistent 1318 // attributes of the heap regions (as they might be modified while iterating). 1319 void heap_region_par_iterate(HeapRegionClosure* cl, 1320 uint worker_id, 1321 HeapRegionClaimer* hrclaimer, 1322 bool concurrent = false) const; 1323 1324 // Clear the cached cset start regions and (more importantly) 1325 // the time stamps. Called when we reset the GC time stamp. 1326 void clear_cset_start_regions(); 1327 1328 // Given the id of a worker, obtain or calculate a suitable 1329 // starting region for iterating over the current collection set. 1330 HeapRegion* start_cset_region_for_worker(uint worker_i); 1331 1332 // Iterate over the regions (if any) in the current collection set. 1333 void collection_set_iterate(HeapRegionClosure* blk); 1334 1335 // As above but starting from region r 1336 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1337 1338 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1339 1340 // Returns the HeapRegion that contains addr. addr must not be NULL. 1341 template <class T> 1342 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1343 1344 // Returns the HeapRegion that contains addr. addr must not be NULL. 1345 // If addr is within a humongous continues region, it returns its humongous start region. 1346 template <class T> 1347 inline HeapRegion* heap_region_containing(const T addr) const; 1348 1349 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1350 // each address in the (reserved) heap is a member of exactly 1351 // one block. The defining characteristic of a block is that it is 1352 // possible to find its size, and thus to progress forward to the next 1353 // block. (Blocks may be of different sizes.) Thus, blocks may 1354 // represent Java objects, or they might be free blocks in a 1355 // free-list-based heap (or subheap), as long as the two kinds are 1356 // distinguishable and the size of each is determinable. 1357 1358 // Returns the address of the start of the "block" that contains the 1359 // address "addr". We say "blocks" instead of "object" since some heaps 1360 // may not pack objects densely; a chunk may either be an object or a 1361 // non-object. 1362 virtual HeapWord* block_start(const void* addr) const; 1363 1364 // Requires "addr" to be the start of a chunk, and returns its size. 1365 // "addr + size" is required to be the start of a new chunk, or the end 1366 // of the active area of the heap. 1367 virtual size_t block_size(const HeapWord* addr) const; 1368 1369 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1370 // the block is an object. 1371 virtual bool block_is_obj(const HeapWord* addr) const; 1372 1373 // Section on thread-local allocation buffers (TLABs) 1374 // See CollectedHeap for semantics. 1375 1376 bool supports_tlab_allocation() const; 1377 size_t tlab_capacity(Thread* ignored) const; 1378 size_t tlab_used(Thread* ignored) const; 1379 size_t max_tlab_size() const; 1380 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1381 1382 // Can a compiler initialize a new object without store barriers? 1383 // This permission only extends from the creation of a new object 1384 // via a TLAB up to the first subsequent safepoint. If such permission 1385 // is granted for this heap type, the compiler promises to call 1386 // defer_store_barrier() below on any slow path allocation of 1387 // a new object for which such initializing store barriers will 1388 // have been elided. G1, like CMS, allows this, but should be 1389 // ready to provide a compensating write barrier as necessary 1390 // if that storage came out of a non-young region. The efficiency 1391 // of this implementation depends crucially on being able to 1392 // answer very efficiently in constant time whether a piece of 1393 // storage in the heap comes from a young region or not. 1394 // See ReduceInitialCardMarks. 1395 virtual bool can_elide_tlab_store_barriers() const { 1396 return true; 1397 } 1398 1399 virtual bool card_mark_must_follow_store() const { 1400 return true; 1401 } 1402 1403 inline bool is_in_young(const oop obj); 1404 1405 virtual bool is_scavengable(const void* addr); 1406 1407 // We don't need barriers for initializing stores to objects 1408 // in the young gen: for the SATB pre-barrier, there is no 1409 // pre-value that needs to be remembered; for the remembered-set 1410 // update logging post-barrier, we don't maintain remembered set 1411 // information for young gen objects. 1412 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1413 1414 // Returns "true" iff the given word_size is "very large". 1415 static bool is_humongous(size_t word_size) { 1416 // Note this has to be strictly greater-than as the TLABs 1417 // are capped at the humongous threshold and we want to 1418 // ensure that we don't try to allocate a TLAB as 1419 // humongous and that we don't allocate a humongous 1420 // object in a TLAB. 1421 return word_size > _humongous_object_threshold_in_words; 1422 } 1423 1424 // Returns the humongous threshold for a specific region size 1425 static size_t humongous_threshold_for(size_t region_size) { 1426 return (region_size / 2); 1427 } 1428 1429 // Update mod union table with the set of dirty cards. 1430 void updateModUnion(); 1431 1432 // Set the mod union bits corresponding to the given memRegion. Note 1433 // that this is always a safe operation, since it doesn't clear any 1434 // bits. 1435 void markModUnionRange(MemRegion mr); 1436 1437 // Print the maximum heap capacity. 1438 virtual size_t max_capacity() const; 1439 1440 virtual jlong millis_since_last_gc(); 1441 1442 1443 // Convenience function to be used in situations where the heap type can be 1444 // asserted to be this type. 1445 static G1CollectedHeap* heap(); 1446 1447 void set_region_short_lived_locked(HeapRegion* hr); 1448 // add appropriate methods for any other surv rate groups 1449 1450 YoungList* young_list() const { return _young_list; } 1451 1452 // debugging 1453 bool check_young_list_well_formed() { 1454 return _young_list->check_list_well_formed(); 1455 } 1456 1457 bool check_young_list_empty(bool check_heap, 1458 bool check_sample = true); 1459 1460 // *** Stuff related to concurrent marking. It's not clear to me that so 1461 // many of these need to be public. 1462 1463 // The functions below are helper functions that a subclass of 1464 // "CollectedHeap" can use in the implementation of its virtual 1465 // functions. 1466 // This performs a concurrent marking of the live objects in a 1467 // bitmap off to the side. 1468 void doConcurrentMark(); 1469 1470 bool isMarkedPrev(oop obj) const; 1471 bool isMarkedNext(oop obj) const; 1472 1473 // Determine if an object is dead, given the object and also 1474 // the region to which the object belongs. An object is dead 1475 // iff a) it was not allocated since the last mark, b) it 1476 // is not marked, and c) it is not in an archive region. 1477 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1478 return 1479 !hr->obj_allocated_since_prev_marking(obj) && 1480 !isMarkedPrev(obj) && 1481 !hr->is_archive(); 1482 } 1483 1484 // This function returns true when an object has been 1485 // around since the previous marking and hasn't yet 1486 // been marked during this marking, and is not in an archive region. 1487 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1488 return 1489 !hr->obj_allocated_since_next_marking(obj) && 1490 !isMarkedNext(obj) && 1491 !hr->is_archive(); 1492 } 1493 1494 // Determine if an object is dead, given only the object itself. 1495 // This will find the region to which the object belongs and 1496 // then call the region version of the same function. 1497 1498 // Added if it is NULL it isn't dead. 1499 1500 inline bool is_obj_dead(const oop obj) const; 1501 1502 inline bool is_obj_ill(const oop obj) const; 1503 1504 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1505 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1506 bool is_marked(oop obj, VerifyOption vo); 1507 const char* top_at_mark_start_str(VerifyOption vo); 1508 1509 ConcurrentMark* concurrent_mark() const { return _cm; } 1510 1511 // Refinement 1512 1513 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1514 1515 // The dirty cards region list is used to record a subset of regions 1516 // whose cards need clearing. The list if populated during the 1517 // remembered set scanning and drained during the card table 1518 // cleanup. Although the methods are reentrant, population/draining 1519 // phases must not overlap. For synchronization purposes the last 1520 // element on the list points to itself. 1521 HeapRegion* _dirty_cards_region_list; 1522 void push_dirty_cards_region(HeapRegion* hr); 1523 HeapRegion* pop_dirty_cards_region(); 1524 1525 // Optimized nmethod scanning support routines 1526 1527 // Register the given nmethod with the G1 heap. 1528 virtual void register_nmethod(nmethod* nm); 1529 1530 // Unregister the given nmethod from the G1 heap. 1531 virtual void unregister_nmethod(nmethod* nm); 1532 1533 // Free up superfluous code root memory. 1534 void purge_code_root_memory(); 1535 1536 // Rebuild the strong code root lists for each region 1537 // after a full GC. 1538 void rebuild_strong_code_roots(); 1539 1540 // Delete entries for dead interned string and clean up unreferenced symbols 1541 // in symbol table, possibly in parallel. 1542 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1543 1544 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1545 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1546 1547 // Redirty logged cards in the refinement queue. 1548 void redirty_logged_cards(); 1549 // Verification 1550 1551 // Perform any cleanup actions necessary before allowing a verification. 1552 virtual void prepare_for_verify(); 1553 1554 // Perform verification. 1555 1556 // vo == UsePrevMarking -> use "prev" marking information, 1557 // vo == UseNextMarking -> use "next" marking information 1558 // vo == UseMarkWord -> use the mark word in the object header 1559 // 1560 // NOTE: Only the "prev" marking information is guaranteed to be 1561 // consistent most of the time, so most calls to this should use 1562 // vo == UsePrevMarking. 1563 // Currently, there is only one case where this is called with 1564 // vo == UseNextMarking, which is to verify the "next" marking 1565 // information at the end of remark. 1566 // Currently there is only one place where this is called with 1567 // vo == UseMarkWord, which is to verify the marking during a 1568 // full GC. 1569 void verify(bool silent, VerifyOption vo); 1570 1571 // Override; it uses the "prev" marking information 1572 virtual void verify(bool silent); 1573 1574 // The methods below are here for convenience and dispatch the 1575 // appropriate method depending on value of the given VerifyOption 1576 // parameter. The values for that parameter, and their meanings, 1577 // are the same as those above. 1578 1579 bool is_obj_dead_cond(const oop obj, 1580 const HeapRegion* hr, 1581 const VerifyOption vo) const; 1582 1583 bool is_obj_dead_cond(const oop obj, 1584 const VerifyOption vo) const; 1585 1586 G1HeapSummary create_g1_heap_summary(); 1587 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1588 1589 // Printing 1590 1591 virtual void print_on(outputStream* st) const; 1592 virtual void print_extended_on(outputStream* st) const; 1593 virtual void print_on_error(outputStream* st) const; 1594 1595 virtual void print_gc_threads_on(outputStream* st) const; 1596 virtual void gc_threads_do(ThreadClosure* tc) const; 1597 1598 // Override 1599 void print_tracing_info() const; 1600 1601 // The following two methods are helpful for debugging RSet issues. 1602 void print_cset_rsets() PRODUCT_RETURN; 1603 void print_all_rsets() PRODUCT_RETURN; 1604 1605 public: 1606 size_t pending_card_num(); 1607 size_t cards_scanned(); 1608 1609 protected: 1610 size_t _max_heap_capacity; 1611 }; 1612 1613 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP