rev 59939 : [mq]: 8243974-investigate-millis-since-last-gc-move
1 /* 2 * Copyright (c) 2001, 2020, 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_GC_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/g1BarrierSet.hpp" 29 #include "gc/g1/g1BiasedArray.hpp" 30 #include "gc/g1/g1CardTable.hpp" 31 #include "gc/g1/g1CollectionSet.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1ConcurrentMark.hpp" 34 #include "gc/g1/g1EdenRegions.hpp" 35 #include "gc/g1/g1EvacFailure.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1EvacuationInfo.hpp" 38 #include "gc/g1/g1GCPhaseTimes.hpp" 39 #include "gc/g1/g1HeapTransition.hpp" 40 #include "gc/g1/g1HeapVerifier.hpp" 41 #include "gc/g1/g1HRPrinter.hpp" 42 #include "gc/g1/g1HeapRegionAttr.hpp" 43 #include "gc/g1/g1MonitoringSupport.hpp" 44 #include "gc/g1/g1NUMA.hpp" 45 #include "gc/g1/g1RedirtyCardsQueue.hpp" 46 #include "gc/g1/g1SurvivorRegions.hpp" 47 #include "gc/g1/g1YCTypes.hpp" 48 #include "gc/g1/heapRegionManager.hpp" 49 #include "gc/g1/heapRegionSet.hpp" 50 #include "gc/g1/heterogeneousHeapRegionManager.hpp" 51 #include "gc/shared/barrierSet.hpp" 52 #include "gc/shared/collectedHeap.hpp" 53 #include "gc/shared/gcHeapSummary.hpp" 54 #include "gc/shared/plab.hpp" 55 #include "gc/shared/preservedMarks.hpp" 56 #include "gc/shared/softRefPolicy.hpp" 57 #include "gc/shared/taskqueue.hpp" 58 #include "memory/memRegion.hpp" 59 #include "utilities/stack.hpp" 60 61 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 62 // It uses the "Garbage First" heap organization and algorithm, which 63 // may combine concurrent marking with parallel, incremental compaction of 64 // heap subsets that will yield large amounts of garbage. 65 66 // Forward declarations 67 class HeapRegion; 68 class GenerationSpec; 69 class G1ParScanThreadState; 70 class G1ParScanThreadStateSet; 71 class G1ParScanThreadState; 72 class MemoryPool; 73 class MemoryManager; 74 class ObjectClosure; 75 class SpaceClosure; 76 class CompactibleSpaceClosure; 77 class Space; 78 class G1CardTableEntryClosure; 79 class G1CollectionSet; 80 class G1Policy; 81 class G1HotCardCache; 82 class G1RemSet; 83 class G1YoungRemSetSamplingThread; 84 class G1ConcurrentMark; 85 class G1ConcurrentMarkThread; 86 class G1ConcurrentRefine; 87 class GenerationCounters; 88 class STWGCTimer; 89 class G1NewTracer; 90 class EvacuationFailedInfo; 91 class nmethod; 92 class WorkGang; 93 class G1Allocator; 94 class G1ArchiveAllocator; 95 class G1FullGCScope; 96 class G1HeapVerifier; 97 class G1HeapSizingPolicy; 98 class G1HeapSummary; 99 class G1EvacSummary; 100 101 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue; 102 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet; 103 104 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 105 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 106 107 // The G1 STW is alive closure. 108 // An instance is embedded into the G1CH and used as the 109 // (optional) _is_alive_non_header closure in the STW 110 // reference processor. It is also extensively used during 111 // reference processing during STW evacuation pauses. 112 class G1STWIsAliveClosure : public BoolObjectClosure { 113 G1CollectedHeap* _g1h; 114 public: 115 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 116 bool do_object_b(oop p); 117 }; 118 119 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure { 120 G1CollectedHeap* _g1h; 121 public: 122 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 123 bool do_object_b(oop p); 124 }; 125 126 class G1RegionMappingChangedListener : public G1MappingChangedListener { 127 private: 128 void reset_from_card_cache(uint start_idx, size_t num_regions); 129 public: 130 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 131 }; 132 133 class G1CollectedHeap : public CollectedHeap { 134 friend class VM_CollectForMetadataAllocation; 135 friend class VM_G1CollectForAllocation; 136 friend class VM_G1CollectFull; 137 friend class VM_G1TryInitiateConcMark; 138 friend class VMStructs; 139 friend class MutatorAllocRegion; 140 friend class G1FullCollector; 141 friend class G1GCAllocRegion; 142 friend class G1HeapVerifier; 143 144 // Closures used in implementation. 145 friend class G1ParScanThreadState; 146 friend class G1ParScanThreadStateSet; 147 friend class G1EvacuateRegionsTask; 148 friend class G1PLABAllocator; 149 150 // Other related classes. 151 friend class HeapRegionClaimer; 152 153 // Testing classes. 154 friend class G1CheckRegionAttrTableClosure; 155 156 private: 157 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 158 159 WorkGang* _workers; 160 G1CardTable* _card_table; 161 162 SoftRefPolicy _soft_ref_policy; 163 164 static size_t _humongous_object_threshold_in_words; 165 166 // Records the end of the most recent collection regardless of type. 167 Ticks _collection_pause_end; 168 169 // For CollectedHeap::millis_since_last_gc() support. Records end of the last 170 // collection that visited all objects. 171 jlong _time_of_last_gc_ns; 172 173 // These sets keep track of old, archive and humongous regions respectively. 174 HeapRegionSet _old_set; 175 HeapRegionSet _archive_set; 176 HeapRegionSet _humongous_set; 177 178 void eagerly_reclaim_humongous_regions(); 179 // Start a new incremental collection set for the next pause. 180 void start_new_collection_set(); 181 182 // The block offset table for the G1 heap. 183 G1BlockOffsetTable* _bot; 184 185 // Tears down the region sets / lists so that they are empty and the 186 // regions on the heap do not belong to a region set / list. The 187 // only exception is the humongous set which we leave unaltered. If 188 // free_list_only is true, it will only tear down the master free 189 // list. It is called before a Full GC (free_list_only == false) or 190 // before heap shrinking (free_list_only == true). 191 void tear_down_region_sets(bool free_list_only); 192 193 // Rebuilds the region sets / lists so that they are repopulated to 194 // reflect the contents of the heap. The only exception is the 195 // humongous set which was not torn down in the first place. If 196 // free_list_only is true, it will only rebuild the master free 197 // list. It is called after a Full GC (free_list_only == false) or 198 // after heap shrinking (free_list_only == true). 199 void rebuild_region_sets(bool free_list_only); 200 201 // Callback for region mapping changed events. 202 G1RegionMappingChangedListener _listener; 203 204 // Handle G1 NUMA support. 205 G1NUMA* _numa; 206 207 // The sequence of all heap regions in the heap. 208 HeapRegionManager* _hrm; 209 210 // Manages all allocations with regions except humongous object allocations. 211 G1Allocator* _allocator; 212 213 // Manages all heap verification. 214 G1HeapVerifier* _verifier; 215 216 // Outside of GC pauses, the number of bytes used in all regions other 217 // than the current allocation region(s). 218 volatile size_t _summary_bytes_used; 219 220 void increase_used(size_t bytes); 221 void decrease_used(size_t bytes); 222 223 void set_used(size_t bytes); 224 225 // Number of bytes used in all regions during GC. Typically changed when 226 // retiring a GC alloc region. 227 size_t _bytes_used_during_gc; 228 229 // Class that handles archive allocation ranges. 230 G1ArchiveAllocator* _archive_allocator; 231 232 // GC allocation statistics policy for survivors. 233 G1EvacStats _survivor_evac_stats; 234 235 // GC allocation statistics policy for tenured objects. 236 G1EvacStats _old_evac_stats; 237 238 // It specifies whether we should attempt to expand the heap after a 239 // region allocation failure. If heap expansion fails we set this to 240 // false so that we don't re-attempt the heap expansion (it's likely 241 // that subsequent expansion attempts will also fail if one fails). 242 // Currently, it is only consulted during GC and it's reset at the 243 // start of each GC. 244 bool _expand_heap_after_alloc_failure; 245 246 // Helper for monitoring and management support. 247 G1MonitoringSupport* _g1mm; 248 249 // Records whether the region at the given index is (still) a 250 // candidate for eager reclaim. Only valid for humongous start 251 // regions; other regions have unspecified values. Humongous start 252 // regions are initialized at start of collection pause, with 253 // candidates removed from the set as they are found reachable from 254 // roots or the young generation. 255 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 256 protected: 257 bool default_value() const { return false; } 258 public: 259 void clear() { G1BiasedMappedArray<bool>::clear(); } 260 void set_candidate(uint region, bool value) { 261 set_by_index(region, value); 262 } 263 bool is_candidate(uint region) { 264 return get_by_index(region); 265 } 266 }; 267 268 HumongousReclaimCandidates _humongous_reclaim_candidates; 269 // Stores whether during humongous object registration we found candidate regions. 270 // If not, we can skip a few steps. 271 bool _has_humongous_reclaim_candidates; 272 273 G1HRPrinter _hr_printer; 274 275 // Return true if an explicit GC should start a concurrent cycle instead 276 // of doing a STW full GC. A concurrent cycle should be started if: 277 // (a) cause == _g1_humongous_allocation, 278 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent, 279 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent, 280 // (d) cause == _wb_conc_mark or _wb_breakpoint, 281 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent. 282 bool should_do_concurrent_full_gc(GCCause::Cause cause); 283 284 // Attempt to start a concurrent cycle with the indicated cause. 285 // precondition: should_do_concurrent_full_gc(cause) 286 bool try_collect_concurrently(GCCause::Cause cause, 287 uint gc_counter, 288 uint old_marking_started_before); 289 290 // Return true if should upgrade to full gc after an incremental one. 291 bool should_upgrade_to_full_gc(GCCause::Cause cause); 292 293 // indicates whether we are in young or mixed GC mode 294 G1CollectorState _collector_state; 295 296 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 297 // concurrent cycles) we have started. 298 volatile uint _old_marking_cycles_started; 299 300 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 301 // concurrent cycles) we have completed. 302 volatile uint _old_marking_cycles_completed; 303 304 // This is a non-product method that is helpful for testing. It is 305 // called at the end of a GC and artificially expands the heap by 306 // allocating a number of dead regions. This way we can induce very 307 // frequent marking cycles and stress the cleanup / concurrent 308 // cleanup code more (as all the regions that will be allocated by 309 // this method will be found dead by the marking cycle). 310 void allocate_dummy_regions() PRODUCT_RETURN; 311 312 // If the HR printer is active, dump the state of the regions in the 313 // heap after a compaction. 314 void print_hrm_post_compaction(); 315 316 // Create a memory mapper for auxiliary data structures of the given size and 317 // translation factor. 318 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 319 size_t size, 320 size_t translation_factor); 321 322 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 323 324 // These are macros so that, if the assert fires, we get the correct 325 // line number, file, etc. 326 327 #define heap_locking_asserts_params(_extra_message_) \ 328 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 329 (_extra_message_), \ 330 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 331 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 332 BOOL_TO_STR(Thread::current()->is_VM_thread()) 333 334 #define assert_heap_locked() \ 335 do { \ 336 assert(Heap_lock->owned_by_self(), \ 337 heap_locking_asserts_params("should be holding the Heap_lock")); \ 338 } while (0) 339 340 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 341 do { \ 342 assert(Heap_lock->owned_by_self() || \ 343 (SafepointSynchronize::is_at_safepoint() && \ 344 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 345 heap_locking_asserts_params("should be holding the Heap_lock or " \ 346 "should be at a safepoint")); \ 347 } while (0) 348 349 #define assert_heap_locked_and_not_at_safepoint() \ 350 do { \ 351 assert(Heap_lock->owned_by_self() && \ 352 !SafepointSynchronize::is_at_safepoint(), \ 353 heap_locking_asserts_params("should be holding the Heap_lock and " \ 354 "should not be at a safepoint")); \ 355 } while (0) 356 357 #define assert_heap_not_locked() \ 358 do { \ 359 assert(!Heap_lock->owned_by_self(), \ 360 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 361 } while (0) 362 363 #define assert_heap_not_locked_and_not_at_safepoint() \ 364 do { \ 365 assert(!Heap_lock->owned_by_self() && \ 366 !SafepointSynchronize::is_at_safepoint(), \ 367 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 368 "should not be at a safepoint")); \ 369 } while (0) 370 371 #define assert_at_safepoint_on_vm_thread() \ 372 do { \ 373 assert_at_safepoint(); \ 374 assert(Thread::current_or_null() != NULL, "no current thread"); \ 375 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 376 } while (0) 377 378 #ifdef ASSERT 379 #define assert_used_and_recalculate_used_equal(g1h) \ 380 do { \ 381 size_t cur_used_bytes = g1h->used(); \ 382 size_t recal_used_bytes = g1h->recalculate_used(); \ 383 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \ 384 " same as recalculated used(" SIZE_FORMAT ").", \ 385 cur_used_bytes, recal_used_bytes); \ 386 } while (0) 387 #else 388 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0) 389 #endif 390 391 const char* young_gc_name() const; 392 393 // The young region list. 394 G1EdenRegions _eden; 395 G1SurvivorRegions _survivor; 396 397 STWGCTimer* _gc_timer_stw; 398 399 G1NewTracer* _gc_tracer_stw; 400 401 // The current policy object for the collector. 402 G1Policy* _policy; 403 G1HeapSizingPolicy* _heap_sizing_policy; 404 405 G1CollectionSet _collection_set; 406 407 // Try to allocate a single non-humongous HeapRegion sufficient for 408 // an allocation of the given word_size. If do_expand is true, 409 // attempt to expand the heap if necessary to satisfy the allocation 410 // request. 'type' takes the type of region to be allocated. (Use constants 411 // Old, Eden, Humongous, Survivor defined in HeapRegionType.) 412 HeapRegion* new_region(size_t word_size, 413 HeapRegionType type, 414 bool do_expand, 415 uint node_index = G1NUMA::AnyNodeIndex); 416 417 // Initialize a contiguous set of free regions of length num_regions 418 // and starting at index first so that they appear as a single 419 // humongous region. 420 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 421 uint num_regions, 422 size_t word_size); 423 424 // Attempt to allocate a humongous object of the given size. Return 425 // NULL if unsuccessful. 426 HeapWord* humongous_obj_allocate(size_t word_size); 427 428 // The following two methods, allocate_new_tlab() and 429 // mem_allocate(), are the two main entry points from the runtime 430 // into the G1's allocation routines. They have the following 431 // assumptions: 432 // 433 // * They should both be called outside safepoints. 434 // 435 // * They should both be called without holding the Heap_lock. 436 // 437 // * All allocation requests for new TLABs should go to 438 // allocate_new_tlab(). 439 // 440 // * All non-TLAB allocation requests should go to mem_allocate(). 441 // 442 // * If either call cannot satisfy the allocation request using the 443 // current allocating region, they will try to get a new one. If 444 // this fails, they will attempt to do an evacuation pause and 445 // retry the allocation. 446 // 447 // * If all allocation attempts fail, even after trying to schedule 448 // an evacuation pause, allocate_new_tlab() will return NULL, 449 // whereas mem_allocate() will attempt a heap expansion and/or 450 // schedule a Full GC. 451 // 452 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 453 // should never be called with word_size being humongous. All 454 // humongous allocation requests should go to mem_allocate() which 455 // will satisfy them with a special path. 456 457 virtual HeapWord* allocate_new_tlab(size_t min_size, 458 size_t requested_size, 459 size_t* actual_size); 460 461 virtual HeapWord* mem_allocate(size_t word_size, 462 bool* gc_overhead_limit_was_exceeded); 463 464 // First-level mutator allocation attempt: try to allocate out of 465 // the mutator alloc region without taking the Heap_lock. This 466 // should only be used for non-humongous allocations. 467 inline HeapWord* attempt_allocation(size_t min_word_size, 468 size_t desired_word_size, 469 size_t* actual_word_size); 470 471 // Second-level mutator allocation attempt: take the Heap_lock and 472 // retry the allocation attempt, potentially scheduling a GC 473 // pause. This should only be used for non-humongous allocations. 474 HeapWord* attempt_allocation_slow(size_t word_size); 475 476 // Takes the Heap_lock and attempts a humongous allocation. It can 477 // potentially schedule a GC pause. 478 HeapWord* attempt_allocation_humongous(size_t word_size); 479 480 // Allocation attempt that should be called during safepoints (e.g., 481 // at the end of a successful GC). expect_null_mutator_alloc_region 482 // specifies whether the mutator alloc region is expected to be NULL 483 // or not. 484 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 485 bool expect_null_mutator_alloc_region); 486 487 // These methods are the "callbacks" from the G1AllocRegion class. 488 489 // For mutator alloc regions. 490 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index); 491 void retire_mutator_alloc_region(HeapRegion* alloc_region, 492 size_t allocated_bytes); 493 494 // For GC alloc regions. 495 bool has_more_regions(G1HeapRegionAttr dest); 496 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index); 497 void retire_gc_alloc_region(HeapRegion* alloc_region, 498 size_t allocated_bytes, G1HeapRegionAttr dest); 499 500 // - if explicit_gc is true, the GC is for a System.gc() etc, 501 // otherwise it's for a failed allocation. 502 // - if clear_all_soft_refs is true, all soft references should be 503 // cleared during the GC. 504 // - it returns false if it is unable to do the collection due to the 505 // GC locker being active, true otherwise. 506 bool do_full_collection(bool explicit_gc, 507 bool clear_all_soft_refs); 508 509 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 510 virtual void do_full_collection(bool clear_all_soft_refs); 511 512 // Callback from VM_G1CollectForAllocation operation. 513 // This function does everything necessary/possible to satisfy a 514 // failed allocation request (including collection, expansion, etc.) 515 HeapWord* satisfy_failed_allocation(size_t word_size, 516 bool* succeeded); 517 // Internal helpers used during full GC to split it up to 518 // increase readability. 519 void abort_concurrent_cycle(); 520 void verify_before_full_collection(bool explicit_gc); 521 void prepare_heap_for_full_collection(); 522 void prepare_heap_for_mutators(); 523 void abort_refinement(); 524 void verify_after_full_collection(); 525 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 526 527 // Helper method for satisfy_failed_allocation() 528 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 529 bool do_gc, 530 bool clear_all_soft_refs, 531 bool expect_null_mutator_alloc_region, 532 bool* gc_succeeded); 533 534 // Attempting to expand the heap sufficiently 535 // to support an allocation of the given "word_size". If 536 // successful, perform the allocation and return the address of the 537 // allocated block, or else "NULL". 538 HeapWord* expand_and_allocate(size_t word_size); 539 540 // Process any reference objects discovered. 541 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 542 543 // If during an initial mark pause we may install a pending list head which is not 544 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking 545 // to discover. 546 void make_pending_list_reachable(); 547 548 // Merges the information gathered on a per-thread basis for all worker threads 549 // during GC into global variables. 550 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 551 552 void verify_numa_regions(const char* desc); 553 554 public: 555 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 556 557 WorkGang* workers() const { return _workers; } 558 559 // Runs the given AbstractGangTask with the current active workers, returning the 560 // total time taken. 561 Tickspan run_task(AbstractGangTask* task); 562 563 G1Allocator* allocator() { 564 return _allocator; 565 } 566 567 G1HeapVerifier* verifier() { 568 return _verifier; 569 } 570 571 G1MonitoringSupport* g1mm() { 572 assert(_g1mm != NULL, "should have been initialized"); 573 return _g1mm; 574 } 575 576 void resize_heap_if_necessary(); 577 578 G1NUMA* numa() const { return _numa; } 579 580 // Expand the garbage-first heap by at least the given size (in bytes!). 581 // Returns true if the heap was expanded by the requested amount; 582 // false otherwise. 583 // (Rounds up to a HeapRegion boundary.) 584 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 585 bool expand_single_region(uint node_index); 586 587 // Returns the PLAB statistics for a given destination. 588 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest); 589 590 // Determines PLAB size for a given destination. 591 inline size_t desired_plab_sz(G1HeapRegionAttr dest); 592 593 // Do anything common to GC's. 594 void gc_prologue(bool full); 595 void gc_epilogue(bool full); 596 597 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 598 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 599 600 // Modify the reclaim candidate set and test for presence. 601 // These are only valid for starts_humongous regions. 602 inline void set_humongous_reclaim_candidate(uint region, bool value); 603 inline bool is_humongous_reclaim_candidate(uint region); 604 inline void set_has_humongous_reclaim_candidate(bool value); 605 606 // Remove from the reclaim candidate set. Also remove from the 607 // collection set so that later encounters avoid the slow path. 608 inline void set_humongous_is_live(oop obj); 609 610 // Register the given region to be part of the collection set. 611 inline void register_humongous_region_with_region_attr(uint index); 612 613 // We register a region with the fast "in collection set" test. We 614 // simply set to true the array slot corresponding to this region. 615 void register_young_region_with_region_attr(HeapRegion* r) { 616 _region_attr.set_in_young(r->hrm_index()); 617 } 618 inline void register_region_with_region_attr(HeapRegion* r); 619 inline void register_old_region_with_region_attr(HeapRegion* r); 620 inline void register_optional_region_with_region_attr(HeapRegion* r); 621 622 void clear_region_attr(const HeapRegion* hr) { 623 _region_attr.clear(hr); 624 } 625 626 void clear_region_attr() { 627 _region_attr.clear(); 628 } 629 630 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking 631 // for all regions. 632 void verify_region_attr_remset_update() PRODUCT_RETURN; 633 634 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 635 636 // This is called at the start of either a concurrent cycle or a Full 637 // GC to update the number of old marking cycles started. 638 void increment_old_marking_cycles_started(); 639 640 // This is called at the end of either a concurrent cycle or a Full 641 // GC to update the number of old marking cycles completed. Those two 642 // can happen in a nested fashion, i.e., we start a concurrent 643 // cycle, a Full GC happens half-way through it which ends first, 644 // and then the cycle notices that a Full GC happened and ends 645 // too. The concurrent parameter is a boolean to help us do a bit 646 // tighter consistency checking in the method. If concurrent is 647 // false, the caller is the inner caller in the nesting (i.e., the 648 // Full GC). If concurrent is true, the caller is the outer caller 649 // in this nesting (i.e., the concurrent cycle). Further nesting is 650 // not currently supported. The end of this call also notifies 651 // the G1OldGCCount_lock in case a Java thread is waiting for a full 652 // GC to happen (e.g., it called System.gc() with 653 // +ExplicitGCInvokesConcurrent). 654 void increment_old_marking_cycles_completed(bool concurrent); 655 656 uint old_marking_cycles_completed() { 657 return _old_marking_cycles_completed; 658 } 659 660 G1HRPrinter* hr_printer() { return &_hr_printer; } 661 662 // Allocates a new heap region instance. 663 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 664 665 // Allocate the highest free region in the reserved heap. This will commit 666 // regions as necessary. 667 HeapRegion* alloc_highest_free_region(); 668 669 // Frees a region by resetting its metadata and adding it to the free list 670 // passed as a parameter (this is usually a local list which will be appended 671 // to the master free list later or NULL if free list management is handled 672 // in another way). 673 // Callers must ensure they are the only one calling free on the given region 674 // at the same time. 675 void free_region(HeapRegion* hr, FreeRegionList* free_list); 676 677 // It dirties the cards that cover the block so that the post 678 // write barrier never queues anything when updating objects on this 679 // block. It is assumed (and in fact we assert) that the block 680 // belongs to a young region. 681 inline void dirty_young_block(HeapWord* start, size_t word_size); 682 683 // Frees a humongous region by collapsing it into individual regions 684 // and calling free_region() for each of them. The freed regions 685 // will be added to the free list that's passed as a parameter (this 686 // is usually a local list which will be appended to the master free 687 // list later). 688 // The method assumes that only a single thread is ever calling 689 // this for a particular region at once. 690 void free_humongous_region(HeapRegion* hr, 691 FreeRegionList* free_list); 692 693 // Facility for allocating in 'archive' regions in high heap memory and 694 // recording the allocated ranges. These should all be called from the 695 // VM thread at safepoints, without the heap lock held. They can be used 696 // to create and archive a set of heap regions which can be mapped at the 697 // same fixed addresses in a subsequent JVM invocation. 698 void begin_archive_alloc_range(bool open = false); 699 700 // Check if the requested size would be too large for an archive allocation. 701 bool is_archive_alloc_too_large(size_t word_size); 702 703 // Allocate memory of the requested size from the archive region. This will 704 // return NULL if the size is too large or if no memory is available. It 705 // does not trigger a garbage collection. 706 HeapWord* archive_mem_allocate(size_t word_size); 707 708 // Optionally aligns the end address and returns the allocated ranges in 709 // an array of MemRegions in order of ascending addresses. 710 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 711 size_t end_alignment_in_bytes = 0); 712 713 // Facility for allocating a fixed range within the heap and marking 714 // the containing regions as 'archive'. For use at JVM init time, when the 715 // caller may mmap archived heap data at the specified range(s). 716 // Verify that the MemRegions specified in the argument array are within the 717 // reserved heap. 718 bool check_archive_addresses(MemRegion* range, size_t count); 719 720 // Commit the appropriate G1 regions containing the specified MemRegions 721 // and mark them as 'archive' regions. The regions in the array must be 722 // non-overlapping and in order of ascending address. 723 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 724 725 // Insert any required filler objects in the G1 regions around the specified 726 // ranges to make the regions parseable. This must be called after 727 // alloc_archive_regions, and after class loading has occurred. 728 void fill_archive_regions(MemRegion* range, size_t count); 729 730 // For each of the specified MemRegions, uncommit the containing G1 regions 731 // which had been allocated by alloc_archive_regions. This should be called 732 // rather than fill_archive_regions at JVM init time if the archive file 733 // mapping failed, with the same non-overlapping and sorted MemRegion array. 734 void dealloc_archive_regions(MemRegion* range, size_t count); 735 736 oop materialize_archived_object(oop obj); 737 738 private: 739 740 // Shrink the garbage-first heap by at most the given size (in bytes!). 741 // (Rounds down to a HeapRegion boundary.) 742 void shrink(size_t expand_bytes); 743 void shrink_helper(size_t expand_bytes); 744 745 #if TASKQUEUE_STATS 746 static void print_taskqueue_stats_hdr(outputStream* const st); 747 void print_taskqueue_stats() const; 748 void reset_taskqueue_stats(); 749 #endif // TASKQUEUE_STATS 750 751 // Schedule the VM operation that will do an evacuation pause to 752 // satisfy an allocation request of word_size. *succeeded will 753 // return whether the VM operation was successful (it did do an 754 // evacuation pause) or not (another thread beat us to it or the GC 755 // locker was active). Given that we should not be holding the 756 // Heap_lock when we enter this method, we will pass the 757 // gc_count_before (i.e., total_collections()) as a parameter since 758 // it has to be read while holding the Heap_lock. Currently, both 759 // methods that call do_collection_pause() release the Heap_lock 760 // before the call, so it's easy to read gc_count_before just before. 761 HeapWord* do_collection_pause(size_t word_size, 762 uint gc_count_before, 763 bool* succeeded, 764 GCCause::Cause gc_cause); 765 766 void wait_for_root_region_scanning(); 767 768 // Perform an incremental collection at a safepoint, possibly 769 // followed by a by-policy upgrade to a full collection. Returns 770 // false if unable to do the collection due to the GC locker being 771 // active, true otherwise. 772 // precondition: at safepoint on VM thread 773 // precondition: !is_gc_active() 774 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 775 776 // Helper for do_collection_pause_at_safepoint, containing the guts 777 // of the incremental collection pause, executed by the vm thread. 778 void do_collection_pause_at_safepoint_helper(double target_pause_time_ms); 779 780 G1HeapVerifier::G1VerifyType young_collection_verify_type() const; 781 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type); 782 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type); 783 784 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms); 785 786 // Actually do the work of evacuating the parts of the collection set. 787 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states); 788 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states); 789 private: 790 // Evacuate the next set of optional regions. 791 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states); 792 793 public: 794 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 795 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 796 G1RedirtyCardsQueueSet* rdcqs, 797 G1ParScanThreadStateSet* pss); 798 799 void expand_heap_after_young_collection(); 800 // Update object copying statistics. 801 void record_obj_copy_mem_stats(); 802 803 // The hot card cache for remembered set insertion optimization. 804 G1HotCardCache* _hot_card_cache; 805 806 // The g1 remembered set of the heap. 807 G1RemSet* _rem_set; 808 809 // After a collection pause, convert the regions in the collection set into free 810 // regions. 811 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 812 813 // Abandon the current collection set without recording policy 814 // statistics or updating free lists. 815 void abandon_collection_set(G1CollectionSet* collection_set); 816 817 // The concurrent marker (and the thread it runs in.) 818 G1ConcurrentMark* _cm; 819 G1ConcurrentMarkThread* _cm_thread; 820 821 // The concurrent refiner. 822 G1ConcurrentRefine* _cr; 823 824 // The parallel task queues 825 G1ScannerTasksQueueSet *_task_queues; 826 827 // True iff a evacuation has failed in the current collection. 828 bool _evacuation_failed; 829 830 EvacuationFailedInfo* _evacuation_failed_info_array; 831 832 // Failed evacuations cause some logical from-space objects to have 833 // forwarding pointers to themselves. Reset them. 834 void remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs); 835 836 // Restore the objects in the regions in the collection set after an 837 // evacuation failure. 838 void restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs); 839 840 PreservedMarksSet _preserved_marks_set; 841 842 // Preserve the mark of "obj", if necessary, in preparation for its mark 843 // word being overwritten with a self-forwarding-pointer. 844 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m); 845 846 #ifndef PRODUCT 847 // Support for forcing evacuation failures. Analogous to 848 // PromotionFailureALot for the other collectors. 849 850 // Records whether G1EvacuationFailureALot should be in effect 851 // for the current GC 852 bool _evacuation_failure_alot_for_current_gc; 853 854 // Used to record the GC number for interval checking when 855 // determining whether G1EvaucationFailureALot is in effect 856 // for the current GC. 857 size_t _evacuation_failure_alot_gc_number; 858 859 // Count of the number of evacuations between failures. 860 volatile size_t _evacuation_failure_alot_count; 861 862 // Set whether G1EvacuationFailureALot should be in effect 863 // for the current GC (based upon the type of GC and which 864 // command line flags are set); 865 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, 866 bool during_initial_mark, 867 bool mark_or_rebuild_in_progress); 868 869 inline void set_evacuation_failure_alot_for_current_gc(); 870 871 // Return true if it's time to cause an evacuation failure. 872 inline bool evacuation_should_fail(); 873 874 // Reset the G1EvacuationFailureALot counters. Should be called at 875 // the end of an evacuation pause in which an evacuation failure occurred. 876 inline void reset_evacuation_should_fail(); 877 #endif // !PRODUCT 878 879 // ("Weak") Reference processing support. 880 // 881 // G1 has 2 instances of the reference processor class. One 882 // (_ref_processor_cm) handles reference object discovery 883 // and subsequent processing during concurrent marking cycles. 884 // 885 // The other (_ref_processor_stw) handles reference object 886 // discovery and processing during full GCs and incremental 887 // evacuation pauses. 888 // 889 // During an incremental pause, reference discovery will be 890 // temporarily disabled for _ref_processor_cm and will be 891 // enabled for _ref_processor_stw. At the end of the evacuation 892 // pause references discovered by _ref_processor_stw will be 893 // processed and discovery will be disabled. The previous 894 // setting for reference object discovery for _ref_processor_cm 895 // will be re-instated. 896 // 897 // At the start of marking: 898 // * Discovery by the CM ref processor is verified to be inactive 899 // and it's discovered lists are empty. 900 // * Discovery by the CM ref processor is then enabled. 901 // 902 // At the end of marking: 903 // * Any references on the CM ref processor's discovered 904 // lists are processed (possibly MT). 905 // 906 // At the start of full GC we: 907 // * Disable discovery by the CM ref processor and 908 // empty CM ref processor's discovered lists 909 // (without processing any entries). 910 // * Verify that the STW ref processor is inactive and it's 911 // discovered lists are empty. 912 // * Temporarily set STW ref processor discovery as single threaded. 913 // * Temporarily clear the STW ref processor's _is_alive_non_header 914 // field. 915 // * Finally enable discovery by the STW ref processor. 916 // 917 // The STW ref processor is used to record any discovered 918 // references during the full GC. 919 // 920 // At the end of a full GC we: 921 // * Enqueue any reference objects discovered by the STW ref processor 922 // that have non-live referents. This has the side-effect of 923 // making the STW ref processor inactive by disabling discovery. 924 // * Verify that the CM ref processor is still inactive 925 // and no references have been placed on it's discovered 926 // lists (also checked as a precondition during initial marking). 927 928 // The (stw) reference processor... 929 ReferenceProcessor* _ref_processor_stw; 930 931 // During reference object discovery, the _is_alive_non_header 932 // closure (if non-null) is applied to the referent object to 933 // determine whether the referent is live. If so then the 934 // reference object does not need to be 'discovered' and can 935 // be treated as a regular oop. This has the benefit of reducing 936 // the number of 'discovered' reference objects that need to 937 // be processed. 938 // 939 // Instance of the is_alive closure for embedding into the 940 // STW reference processor as the _is_alive_non_header field. 941 // Supplying a value for the _is_alive_non_header field is 942 // optional but doing so prevents unnecessary additions to 943 // the discovered lists during reference discovery. 944 G1STWIsAliveClosure _is_alive_closure_stw; 945 946 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 947 948 // The (concurrent marking) reference processor... 949 ReferenceProcessor* _ref_processor_cm; 950 951 // Instance of the concurrent mark is_alive closure for embedding 952 // into the Concurrent Marking reference processor as the 953 // _is_alive_non_header field. Supplying a value for the 954 // _is_alive_non_header field is optional but doing so prevents 955 // unnecessary additions to the discovered lists during reference 956 // discovery. 957 G1CMIsAliveClosure _is_alive_closure_cm; 958 959 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 960 public: 961 962 G1ScannerTasksQueue* task_queue(uint i) const; 963 964 uint num_task_queues() const; 965 966 // Create a G1CollectedHeap. 967 // Must call the initialize method afterwards. 968 // May not return if something goes wrong. 969 G1CollectedHeap(); 970 971 private: 972 jint initialize_concurrent_refinement(); 973 jint initialize_young_gen_sampling_thread(); 974 public: 975 // Initialize the G1CollectedHeap to have the initial and 976 // maximum sizes and remembered and barrier sets 977 // specified by the policy object. 978 jint initialize(); 979 980 virtual void stop(); 981 virtual void safepoint_synchronize_begin(); 982 virtual void safepoint_synchronize_end(); 983 984 // Does operations required after initialization has been done. 985 void post_initialize(); 986 987 // Initialize weak reference processing. 988 void ref_processing_init(); 989 990 virtual Name kind() const { 991 return CollectedHeap::G1; 992 } 993 994 virtual const char* name() const { 995 return "G1"; 996 } 997 998 const G1CollectorState* collector_state() const { return &_collector_state; } 999 G1CollectorState* collector_state() { return &_collector_state; } 1000 1001 // The current policy object for the collector. 1002 G1Policy* policy() const { return _policy; } 1003 // The remembered set. 1004 G1RemSet* rem_set() const { return _rem_set; } 1005 1006 inline G1GCPhaseTimes* phase_times() const; 1007 1008 HeapRegionManager* hrm() const { return _hrm; } 1009 1010 const G1CollectionSet* collection_set() const { return &_collection_set; } 1011 G1CollectionSet* collection_set() { return &_collection_set; } 1012 1013 virtual SoftRefPolicy* soft_ref_policy(); 1014 1015 virtual void initialize_serviceability(); 1016 virtual MemoryUsage memory_usage(); 1017 virtual GrowableArray<GCMemoryManager*> memory_managers(); 1018 virtual GrowableArray<MemoryPool*> memory_pools(); 1019 1020 // Try to minimize the remembered set. 1021 void scrub_rem_set(); 1022 1023 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1024 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id); 1025 1026 // The shared block offset table array. 1027 G1BlockOffsetTable* bot() const { return _bot; } 1028 1029 // Reference Processing accessors 1030 1031 // The STW reference processor.... 1032 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1033 1034 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1035 1036 // The Concurrent Marking reference processor... 1037 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1038 1039 size_t unused_committed_regions_in_bytes() const; 1040 1041 virtual size_t capacity() const; 1042 virtual size_t used() const; 1043 // This should be called when we're not holding the heap lock. The 1044 // result might be a bit inaccurate. 1045 size_t used_unlocked() const; 1046 size_t recalculate_used() const; 1047 1048 // These virtual functions do the actual allocation. 1049 // Some heaps may offer a contiguous region for shared non-blocking 1050 // allocation, via inlined code (by exporting the address of the top and 1051 // end fields defining the extent of the contiguous allocation region.) 1052 // But G1CollectedHeap doesn't yet support this. 1053 1054 virtual bool is_maximal_no_gc() const { 1055 return _hrm->available() == 0; 1056 } 1057 1058 // Returns whether there are any regions left in the heap for allocation. 1059 bool has_regions_left_for_allocation() const { 1060 return !is_maximal_no_gc() || num_free_regions() != 0; 1061 } 1062 1063 // The current number of regions in the heap. 1064 uint num_regions() const { return _hrm->length(); } 1065 1066 // The max number of regions in the heap. 1067 uint max_regions() const { return _hrm->max_length(); } 1068 1069 // Max number of regions that can be comitted. 1070 uint max_expandable_regions() const { return _hrm->max_expandable_length(); } 1071 1072 // The number of regions that are completely free. 1073 uint num_free_regions() const { return _hrm->num_free_regions(); } 1074 1075 // The number of regions that can be allocated into. 1076 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); } 1077 1078 MemoryUsage get_auxiliary_data_memory_usage() const { 1079 return _hrm->get_auxiliary_data_memory_usage(); 1080 } 1081 1082 // The number of regions that are not completely free. 1083 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1084 1085 #ifdef ASSERT 1086 bool is_on_master_free_list(HeapRegion* hr) { 1087 return _hrm->is_free(hr); 1088 } 1089 #endif // ASSERT 1090 1091 inline void old_set_add(HeapRegion* hr); 1092 inline void old_set_remove(HeapRegion* hr); 1093 1094 inline void archive_set_add(HeapRegion* hr); 1095 1096 size_t non_young_capacity_bytes() { 1097 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1098 } 1099 1100 // Determine whether the given region is one that we are using as an 1101 // old GC alloc region. 1102 bool is_old_gc_alloc_region(HeapRegion* hr); 1103 1104 // Perform a collection of the heap; intended for use in implementing 1105 // "System.gc". This probably implies as full a collection as the 1106 // "CollectedHeap" supports. 1107 virtual void collect(GCCause::Cause cause); 1108 1109 // Perform a collection of the heap with the given cause. 1110 // Returns whether this collection actually executed. 1111 bool try_collect(GCCause::Cause cause); 1112 1113 // True iff an evacuation has failed in the most-recent collection. 1114 bool evacuation_failed() { return _evacuation_failed; } 1115 1116 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1117 void prepend_to_freelist(FreeRegionList* list); 1118 void decrement_summary_bytes(size_t bytes); 1119 1120 virtual bool is_in(const void* p) const; 1121 #ifdef ASSERT 1122 // Returns whether p is in one of the available areas of the heap. Slow but 1123 // extensive version. 1124 bool is_in_exact(const void* p) const; 1125 #endif 1126 1127 // Return "TRUE" iff the given object address is within the collection 1128 // set. Assumes that the reference points into the heap. 1129 inline bool is_in_cset(const HeapRegion *hr); 1130 inline bool is_in_cset(oop obj); 1131 inline bool is_in_cset(HeapWord* addr); 1132 1133 inline bool is_in_cset_or_humongous(const oop obj); 1134 1135 private: 1136 // This array is used for a quick test on whether a reference points into 1137 // the collection set or not. Each of the array's elements denotes whether the 1138 // corresponding region is in the collection set or not. 1139 G1HeapRegionAttrBiasedMappedArray _region_attr; 1140 1141 public: 1142 1143 inline G1HeapRegionAttr region_attr(const void* obj) const; 1144 inline G1HeapRegionAttr region_attr(uint idx) const; 1145 1146 // Return "TRUE" iff the given object address is in the reserved 1147 // region of g1. 1148 bool is_in_g1_reserved(const void* p) const { 1149 return _hrm->reserved().contains(p); 1150 } 1151 1152 // Returns a MemRegion that corresponds to the space that has been 1153 // reserved for the heap 1154 MemRegion g1_reserved() const { 1155 return _hrm->reserved(); 1156 } 1157 1158 MemRegion reserved_region() const { 1159 return _reserved; 1160 } 1161 1162 HeapWord* base() const { 1163 return _reserved.start(); 1164 } 1165 1166 bool is_in_reserved(const void* addr) const { 1167 return _reserved.contains(addr); 1168 } 1169 1170 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; } 1171 1172 G1CardTable* card_table() const { 1173 return _card_table; 1174 } 1175 1176 // Iteration functions. 1177 1178 // Iterate over all objects, calling "cl.do_object" on each. 1179 virtual void object_iterate(ObjectClosure* cl); 1180 1181 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1182 virtual void keep_alive(oop obj); 1183 1184 // Iterate over heap regions, in address order, terminating the 1185 // iteration early if the "do_heap_region" method returns "true". 1186 void heap_region_iterate(HeapRegionClosure* blk) const; 1187 1188 // Return the region with the given index. It assumes the index is valid. 1189 inline HeapRegion* region_at(uint index) const; 1190 inline HeapRegion* region_at_or_null(uint index) const; 1191 1192 // Return the next region (by index) that is part of the same 1193 // humongous object that hr is part of. 1194 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1195 1196 // Calculate the region index of the given address. Given address must be 1197 // within the heap. 1198 inline uint addr_to_region(HeapWord* addr) const; 1199 1200 inline HeapWord* bottom_addr_for_region(uint index) const; 1201 1202 // Two functions to iterate over the heap regions in parallel. Threads 1203 // compete using the HeapRegionClaimer to claim the regions before 1204 // applying the closure on them. 1205 // The _from_worker_offset version uses the HeapRegionClaimer and 1206 // the worker id to calculate a start offset to prevent all workers to 1207 // start from the point. 1208 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1209 HeapRegionClaimer* hrclaimer, 1210 uint worker_id) const; 1211 1212 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1213 HeapRegionClaimer* hrclaimer) const; 1214 1215 // Iterate over all regions in the collection set in parallel. 1216 void collection_set_par_iterate_all(HeapRegionClosure* cl, 1217 HeapRegionClaimer* hr_claimer, 1218 uint worker_id); 1219 1220 // Iterate over all regions currently in the current collection set. 1221 void collection_set_iterate_all(HeapRegionClosure* blk); 1222 1223 // Iterate over the regions in the current increment of the collection set. 1224 // Starts the iteration so that the start regions of a given worker id over the 1225 // set active_workers are evenly spread across the set of collection set regions 1226 // to be iterated. 1227 // The variant with the HeapRegionClaimer guarantees that the closure will be 1228 // applied to a particular region exactly once. 1229 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) { 1230 collection_set_iterate_increment_from(blk, NULL, worker_id); 1231 } 1232 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id); 1233 1234 // Returns the HeapRegion that contains addr. addr must not be NULL. 1235 template <class T> 1236 inline HeapRegion* heap_region_containing(const T addr) const; 1237 1238 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted 1239 // region. addr must not be NULL. 1240 template <class T> 1241 inline HeapRegion* heap_region_containing_or_null(const T addr) const; 1242 1243 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1244 // each address in the (reserved) heap is a member of exactly 1245 // one block. The defining characteristic of a block is that it is 1246 // possible to find its size, and thus to progress forward to the next 1247 // block. (Blocks may be of different sizes.) Thus, blocks may 1248 // represent Java objects, or they might be free blocks in a 1249 // free-list-based heap (or subheap), as long as the two kinds are 1250 // distinguishable and the size of each is determinable. 1251 1252 // Returns the address of the start of the "block" that contains the 1253 // address "addr". We say "blocks" instead of "object" since some heaps 1254 // may not pack objects densely; a chunk may either be an object or a 1255 // non-object. 1256 HeapWord* block_start(const void* addr) const; 1257 1258 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1259 // the block is an object. 1260 bool block_is_obj(const HeapWord* addr) const; 1261 1262 // Section on thread-local allocation buffers (TLABs) 1263 // See CollectedHeap for semantics. 1264 1265 bool supports_tlab_allocation() const; 1266 size_t tlab_capacity(Thread* ignored) const; 1267 size_t tlab_used(Thread* ignored) const; 1268 size_t max_tlab_size() const; 1269 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1270 1271 inline bool is_in_young(const oop obj); 1272 1273 // Returns "true" iff the given word_size is "very large". 1274 static bool is_humongous(size_t word_size) { 1275 // Note this has to be strictly greater-than as the TLABs 1276 // are capped at the humongous threshold and we want to 1277 // ensure that we don't try to allocate a TLAB as 1278 // humongous and that we don't allocate a humongous 1279 // object in a TLAB. 1280 return word_size > _humongous_object_threshold_in_words; 1281 } 1282 1283 // Returns the humongous threshold for a specific region size 1284 static size_t humongous_threshold_for(size_t region_size) { 1285 return (region_size / 2); 1286 } 1287 1288 // Returns the number of regions the humongous object of the given word size 1289 // requires. 1290 static size_t humongous_obj_size_in_regions(size_t word_size); 1291 1292 // Print the maximum heap capacity. 1293 virtual size_t max_capacity() const; 1294 1295 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used. 1296 virtual size_t max_reserved_capacity() const; 1297 1298 Ticks last_collection_pause_end() const { return _collection_pause_end; } 1299 virtual jlong millis_since_last_gc(); 1300 1301 // Convenience function to be used in situations where the heap type can be 1302 // asserted to be this type. 1303 static G1CollectedHeap* heap() { 1304 return named_heap<G1CollectedHeap>(CollectedHeap::G1); 1305 } 1306 1307 void set_region_short_lived_locked(HeapRegion* hr); 1308 // add appropriate methods for any other surv rate groups 1309 1310 const G1SurvivorRegions* survivor() const { return &_survivor; } 1311 1312 uint eden_regions_count() const { return _eden.length(); } 1313 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); } 1314 uint survivor_regions_count() const { return _survivor.length(); } 1315 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); } 1316 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); } 1317 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); } 1318 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1319 uint old_regions_count() const { return _old_set.length(); } 1320 uint archive_regions_count() const { return _archive_set.length(); } 1321 uint humongous_regions_count() const { return _humongous_set.length(); } 1322 1323 #ifdef ASSERT 1324 bool check_young_list_empty(); 1325 #endif 1326 1327 // *** Stuff related to concurrent marking. It's not clear to me that so 1328 // many of these need to be public. 1329 1330 // The functions below are helper functions that a subclass of 1331 // "CollectedHeap" can use in the implementation of its virtual 1332 // functions. 1333 // This performs a concurrent marking of the live objects in a 1334 // bitmap off to the side. 1335 void do_concurrent_mark(); 1336 1337 bool is_marked_next(oop obj) const; 1338 1339 // Determine if an object is dead, given the object and also 1340 // the region to which the object belongs. An object is dead 1341 // iff a) it was not allocated since the last mark, b) it 1342 // is not marked, and c) it is not in an archive region. 1343 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1344 return 1345 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1346 !hr->is_archive(); 1347 } 1348 1349 // This function returns true when an object has been 1350 // around since the previous marking and hasn't yet 1351 // been marked during this marking, and is not in an archive region. 1352 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1353 return 1354 !hr->obj_allocated_since_next_marking(obj) && 1355 !is_marked_next(obj) && 1356 !hr->is_archive(); 1357 } 1358 1359 // Determine if an object is dead, given only the object itself. 1360 // This will find the region to which the object belongs and 1361 // then call the region version of the same function. 1362 1363 // Added if it is NULL it isn't dead. 1364 1365 inline bool is_obj_dead(const oop obj) const; 1366 1367 inline bool is_obj_ill(const oop obj) const; 1368 1369 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1370 inline bool is_obj_dead_full(const oop obj) const; 1371 1372 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1373 1374 // Refinement 1375 1376 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1377 1378 // Optimized nmethod scanning support routines 1379 1380 // Register the given nmethod with the G1 heap. 1381 virtual void register_nmethod(nmethod* nm); 1382 1383 // Unregister the given nmethod from the G1 heap. 1384 virtual void unregister_nmethod(nmethod* nm); 1385 1386 // No nmethod flushing needed. 1387 virtual void flush_nmethod(nmethod* nm) {} 1388 1389 // No nmethod verification implemented. 1390 virtual void verify_nmethod(nmethod* nm) {} 1391 1392 // Free up superfluous code root memory. 1393 void purge_code_root_memory(); 1394 1395 // Rebuild the strong code root lists for each region 1396 // after a full GC. 1397 void rebuild_strong_code_roots(); 1398 1399 // Partial cleaning of VM internal data structures. 1400 void string_dedup_cleaning(BoolObjectClosure* is_alive, 1401 OopClosure* keep_alive, 1402 G1GCPhaseTimes* phase_times = NULL); 1403 1404 // Performs cleaning of data structures after class unloading. 1405 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1406 1407 // Redirty logged cards in the refinement queue. 1408 void redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs); 1409 1410 // Verification 1411 1412 // Deduplicate the string 1413 virtual void deduplicate_string(oop str); 1414 1415 // Perform any cleanup actions necessary before allowing a verification. 1416 virtual void prepare_for_verify(); 1417 1418 // Perform verification. 1419 1420 // vo == UsePrevMarking -> use "prev" marking information, 1421 // vo == UseNextMarking -> use "next" marking information 1422 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1423 // 1424 // NOTE: Only the "prev" marking information is guaranteed to be 1425 // consistent most of the time, so most calls to this should use 1426 // vo == UsePrevMarking. 1427 // Currently, there is only one case where this is called with 1428 // vo == UseNextMarking, which is to verify the "next" marking 1429 // information at the end of remark. 1430 // Currently there is only one place where this is called with 1431 // vo == UseFullMarking, which is to verify the marking during a 1432 // full GC. 1433 void verify(VerifyOption vo); 1434 1435 // WhiteBox testing support. 1436 virtual bool supports_concurrent_gc_breakpoints() const; 1437 bool is_heterogeneous_heap() const; 1438 1439 virtual WorkGang* get_safepoint_workers() { return _workers; } 1440 1441 // The methods below are here for convenience and dispatch the 1442 // appropriate method depending on value of the given VerifyOption 1443 // parameter. The values for that parameter, and their meanings, 1444 // are the same as those above. 1445 1446 bool is_obj_dead_cond(const oop obj, 1447 const HeapRegion* hr, 1448 const VerifyOption vo) const; 1449 1450 bool is_obj_dead_cond(const oop obj, 1451 const VerifyOption vo) const; 1452 1453 G1HeapSummary create_g1_heap_summary(); 1454 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1455 1456 // Printing 1457 private: 1458 void print_heap_regions() const; 1459 void print_regions_on(outputStream* st) const; 1460 1461 public: 1462 virtual void print_on(outputStream* st) const; 1463 virtual void print_extended_on(outputStream* st) const; 1464 virtual void print_on_error(outputStream* st) const; 1465 1466 virtual void gc_threads_do(ThreadClosure* tc) const; 1467 1468 // Override 1469 void print_tracing_info() const; 1470 1471 // The following two methods are helpful for debugging RSet issues. 1472 void print_cset_rsets() PRODUCT_RETURN; 1473 void print_all_rsets() PRODUCT_RETURN; 1474 1475 // Used to print information about locations in the hs_err file. 1476 virtual bool print_location(outputStream* st, void* addr) const; 1477 }; 1478 1479 class G1ParEvacuateFollowersClosure : public VoidClosure { 1480 private: 1481 double _start_term; 1482 double _term_time; 1483 size_t _term_attempts; 1484 1485 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1486 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); } 1487 protected: 1488 G1CollectedHeap* _g1h; 1489 G1ParScanThreadState* _par_scan_state; 1490 G1ScannerTasksQueueSet* _queues; 1491 TaskTerminator* _terminator; 1492 G1GCPhaseTimes::GCParPhases _phase; 1493 1494 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1495 G1ScannerTasksQueueSet* queues() { return _queues; } 1496 TaskTerminator* terminator() { return _terminator; } 1497 1498 public: 1499 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1500 G1ParScanThreadState* par_scan_state, 1501 G1ScannerTasksQueueSet* queues, 1502 TaskTerminator* terminator, 1503 G1GCPhaseTimes::GCParPhases phase) 1504 : _start_term(0.0), _term_time(0.0), _term_attempts(0), 1505 _g1h(g1h), _par_scan_state(par_scan_state), 1506 _queues(queues), _terminator(terminator), _phase(phase) {} 1507 1508 void do_void(); 1509 1510 double term_time() const { return _term_time; } 1511 size_t term_attempts() const { return _term_attempts; } 1512 1513 private: 1514 inline bool offer_termination(); 1515 }; 1516 1517 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP --- EOF ---