1 /* 2 * Copyright (c) 2001, 2018, 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/evacuationInfo.hpp" 29 #include "gc/g1/g1BarrierSet.hpp" 30 #include "gc/g1/g1BiasedArray.hpp" 31 #include "gc/g1/g1CardTable.hpp" 32 #include "gc/g1/g1CollectionSet.hpp" 33 #include "gc/g1/g1CollectorState.hpp" 34 #include "gc/g1/g1ConcurrentMark.hpp" 35 #include "gc/g1/g1EdenRegions.hpp" 36 #include "gc/g1/g1EvacFailure.hpp" 37 #include "gc/g1/g1EvacStats.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/g1InCSetState.hpp" 43 #include "gc/g1/g1MonitoringSupport.hpp" 44 #include "gc/g1/g1SurvivorRegions.hpp" 45 #include "gc/g1/g1YCTypes.hpp" 46 #include "gc/g1/heapRegionManager.hpp" 47 #include "gc/g1/heapRegionSet.hpp" 48 #include "gc/shared/barrierSet.hpp" 49 #include "gc/shared/collectedHeap.hpp" 50 #include "gc/shared/gcHeapSummary.hpp" 51 #include "gc/shared/plab.hpp" 52 #include "gc/shared/preservedMarks.hpp" 53 #include "gc/shared/softRefPolicy.hpp" 54 #include "memory/memRegion.hpp" 55 #include "utilities/stack.hpp" 56 57 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 58 // It uses the "Garbage First" heap organization and algorithm, which 59 // may combine concurrent marking with parallel, incremental compaction of 60 // heap subsets that will yield large amounts of garbage. 61 62 // Forward declarations 63 class HeapRegion; 64 class HRRSCleanupTask; 65 class GenerationSpec; 66 class G1ParScanThreadState; 67 class G1ParScanThreadStateSet; 68 class G1ParScanThreadState; 69 class MemoryPool; 70 class MemoryManager; 71 class ObjectClosure; 72 class SpaceClosure; 73 class CompactibleSpaceClosure; 74 class Space; 75 class G1CollectionSet; 76 class G1CollectorPolicy; 77 class G1Policy; 78 class G1HotCardCache; 79 class G1RemSet; 80 class G1YoungRemSetSamplingThread; 81 class HeapRegionRemSetIterator; 82 class G1ConcurrentMark; 83 class G1ConcurrentMarkThread; 84 class G1ConcurrentRefine; 85 class GenerationCounters; 86 class STWGCTimer; 87 class G1NewTracer; 88 class EvacuationFailedInfo; 89 class nmethod; 90 class WorkGang; 91 class G1Allocator; 92 class G1ArchiveAllocator; 93 class G1FullGCScope; 94 class G1HeapVerifier; 95 class G1HeapSizingPolicy; 96 class G1HeapSummary; 97 class G1EvacSummary; 98 99 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 100 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 101 102 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 103 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 104 105 // The G1 STW is alive closure. 106 // An instance is embedded into the G1CH and used as the 107 // (optional) _is_alive_non_header closure in the STW 108 // reference processor. It is also extensively used during 109 // reference processing during STW evacuation pauses. 110 class G1STWIsAliveClosure : public BoolObjectClosure { 111 G1CollectedHeap* _g1h; 112 public: 113 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 114 bool do_object_b(oop p); 115 }; 116 117 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure { 118 G1CollectedHeap* _g1h; 119 public: 120 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 121 bool do_object_b(oop p); 122 }; 123 124 class G1RegionMappingChangedListener : public G1MappingChangedListener { 125 private: 126 void reset_from_card_cache(uint start_idx, size_t num_regions); 127 public: 128 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 129 }; 130 131 class G1CollectedHeap : public CollectedHeap { 132 friend class G1FreeCollectionSetTask; 133 friend class VM_CollectForMetadataAllocation; 134 friend class VM_G1CollectForAllocation; 135 friend class VM_G1CollectFull; 136 friend class VMStructs; 137 friend class MutatorAllocRegion; 138 friend class G1FullCollector; 139 friend class G1GCAllocRegion; 140 friend class G1HeapVerifier; 141 142 // Closures used in implementation. 143 friend class G1ParScanThreadState; 144 friend class G1ParScanThreadStateSet; 145 friend class G1ParTask; 146 friend class G1PLABAllocator; 147 friend class G1PrepareCompactClosure; 148 149 // Other related classes. 150 friend class HeapRegionClaimer; 151 152 // Testing classes. 153 friend class G1CheckCSetFastTableClosure; 154 155 private: 156 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 157 158 WorkGang* _workers; 159 G1CollectorPolicy* _collector_policy; 160 G1CardTable* _card_table; 161 162 SoftRefPolicy _soft_ref_policy; 163 164 static size_t _humongous_object_threshold_in_words; 165 166 // These sets keep track of old, archive and humongous regions respectively. 167 HeapRegionSet _old_set; 168 HeapRegionSet _archive_set; 169 HeapRegionSet _humongous_set; 170 171 void eagerly_reclaim_humongous_regions(); 172 // Start a new incremental collection set for the next pause. 173 void start_new_collection_set(); 174 175 // The block offset table for the G1 heap. 176 G1BlockOffsetTable* _bot; 177 178 // Tears down the region sets / lists so that they are empty and the 179 // regions on the heap do not belong to a region set / list. The 180 // only exception is the humongous set which we leave unaltered. If 181 // free_list_only is true, it will only tear down the master free 182 // list. It is called before a Full GC (free_list_only == false) or 183 // before heap shrinking (free_list_only == true). 184 void tear_down_region_sets(bool free_list_only); 185 186 // Rebuilds the region sets / lists so that they are repopulated to 187 // reflect the contents of the heap. The only exception is the 188 // humongous set which was not torn down in the first place. If 189 // free_list_only is true, it will only rebuild the master free 190 // list. It is called after a Full GC (free_list_only == false) or 191 // after heap shrinking (free_list_only == true). 192 void rebuild_region_sets(bool free_list_only); 193 194 // Callback for region mapping changed events. 195 G1RegionMappingChangedListener _listener; 196 197 // The sequence of all heap regions in the heap. 198 HeapRegionManager _hrm; 199 200 // Manages all allocations with regions except humongous object allocations. 201 G1Allocator* _allocator; 202 203 // Manages all heap verification. 204 G1HeapVerifier* _verifier; 205 206 // Outside of GC pauses, the number of bytes used in all regions other 207 // than the current allocation region(s). 208 size_t _summary_bytes_used; 209 210 void increase_used(size_t bytes); 211 void decrease_used(size_t bytes); 212 213 void set_used(size_t bytes); 214 215 // Class that handles archive allocation ranges. 216 G1ArchiveAllocator* _archive_allocator; 217 218 // GC allocation statistics policy for survivors. 219 G1EvacStats _survivor_evac_stats; 220 221 // GC allocation statistics policy for tenured objects. 222 G1EvacStats _old_evac_stats; 223 224 // It specifies whether we should attempt to expand the heap after a 225 // region allocation failure. If heap expansion fails we set this to 226 // false so that we don't re-attempt the heap expansion (it's likely 227 // that subsequent expansion attempts will also fail if one fails). 228 // Currently, it is only consulted during GC and it's reset at the 229 // start of each GC. 230 bool _expand_heap_after_alloc_failure; 231 232 // Helper for monitoring and management support. 233 G1MonitoringSupport* _g1mm; 234 235 // Records whether the region at the given index is (still) a 236 // candidate for eager reclaim. Only valid for humongous start 237 // regions; other regions have unspecified values. Humongous start 238 // regions are initialized at start of collection pause, with 239 // candidates removed from the set as they are found reachable from 240 // roots or the young generation. 241 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 242 protected: 243 bool default_value() const { return false; } 244 public: 245 void clear() { G1BiasedMappedArray<bool>::clear(); } 246 void set_candidate(uint region, bool value) { 247 set_by_index(region, value); 248 } 249 bool is_candidate(uint region) { 250 return get_by_index(region); 251 } 252 }; 253 254 HumongousReclaimCandidates _humongous_reclaim_candidates; 255 // Stores whether during humongous object registration we found candidate regions. 256 // If not, we can skip a few steps. 257 bool _has_humongous_reclaim_candidates; 258 259 G1HRPrinter _hr_printer; 260 261 // It decides whether an explicit GC should start a concurrent cycle 262 // instead of doing a STW GC. Currently, a concurrent cycle is 263 // explicitly started if: 264 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 265 // (b) cause == _g1_humongous_allocation 266 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 267 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 268 // (e) cause == _wb_conc_mark 269 bool should_do_concurrent_full_gc(GCCause::Cause cause); 270 271 // indicates whether we are in young or mixed GC mode 272 G1CollectorState _collector_state; 273 274 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 275 // concurrent cycles) we have started. 276 volatile uint _old_marking_cycles_started; 277 278 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 279 // concurrent cycles) we have completed. 280 volatile uint _old_marking_cycles_completed; 281 282 // This is a non-product method that is helpful for testing. It is 283 // called at the end of a GC and artificially expands the heap by 284 // allocating a number of dead regions. This way we can induce very 285 // frequent marking cycles and stress the cleanup / concurrent 286 // cleanup code more (as all the regions that will be allocated by 287 // this method will be found dead by the marking cycle). 288 void allocate_dummy_regions() PRODUCT_RETURN; 289 290 // If the HR printer is active, dump the state of the regions in the 291 // heap after a compaction. 292 void print_hrm_post_compaction(); 293 294 // Create a memory mapper for auxiliary data structures of the given size and 295 // translation factor. 296 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 297 size_t size, 298 size_t translation_factor); 299 300 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 301 302 // These are macros so that, if the assert fires, we get the correct 303 // line number, file, etc. 304 305 #define heap_locking_asserts_params(_extra_message_) \ 306 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 307 (_extra_message_), \ 308 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 309 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 310 BOOL_TO_STR(Thread::current()->is_VM_thread()) 311 312 #define assert_heap_locked() \ 313 do { \ 314 assert(Heap_lock->owned_by_self(), \ 315 heap_locking_asserts_params("should be holding the Heap_lock")); \ 316 } while (0) 317 318 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 319 do { \ 320 assert(Heap_lock->owned_by_self() || \ 321 (SafepointSynchronize::is_at_safepoint() && \ 322 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 323 heap_locking_asserts_params("should be holding the Heap_lock or " \ 324 "should be at a safepoint")); \ 325 } while (0) 326 327 #define assert_heap_locked_and_not_at_safepoint() \ 328 do { \ 329 assert(Heap_lock->owned_by_self() && \ 330 !SafepointSynchronize::is_at_safepoint(), \ 331 heap_locking_asserts_params("should be holding the Heap_lock and " \ 332 "should not be at a safepoint")); \ 333 } while (0) 334 335 #define assert_heap_not_locked() \ 336 do { \ 337 assert(!Heap_lock->owned_by_self(), \ 338 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 339 } while (0) 340 341 #define assert_heap_not_locked_and_not_at_safepoint() \ 342 do { \ 343 assert(!Heap_lock->owned_by_self() && \ 344 !SafepointSynchronize::is_at_safepoint(), \ 345 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 346 "should not be at a safepoint")); \ 347 } while (0) 348 349 #define assert_at_safepoint_on_vm_thread() \ 350 do { \ 351 assert_at_safepoint(); \ 352 assert(Thread::current_or_null() != NULL, "no current thread"); \ 353 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 354 } while (0) 355 356 // The young region list. 357 G1EdenRegions _eden; 358 G1SurvivorRegions _survivor; 359 360 STWGCTimer* _gc_timer_stw; 361 362 G1NewTracer* _gc_tracer_stw; 363 364 // The current policy object for the collector. 365 G1Policy* _g1_policy; 366 G1HeapSizingPolicy* _heap_sizing_policy; 367 368 G1CollectionSet _collection_set; 369 370 // Try to allocate a single non-humongous HeapRegion sufficient for 371 // an allocation of the given word_size. If do_expand is true, 372 // attempt to expand the heap if necessary to satisfy the allocation 373 // request. If the region is to be used as an old region or for a 374 // humongous object, set is_old to true. If not, to false. 375 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 376 377 // Initialize a contiguous set of free regions of length num_regions 378 // and starting at index first so that they appear as a single 379 // humongous region. 380 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 381 uint num_regions, 382 size_t word_size); 383 384 // Attempt to allocate a humongous object of the given size. Return 385 // NULL if unsuccessful. 386 HeapWord* humongous_obj_allocate(size_t word_size); 387 388 // The following two methods, allocate_new_tlab() and 389 // mem_allocate(), are the two main entry points from the runtime 390 // into the G1's allocation routines. They have the following 391 // assumptions: 392 // 393 // * They should both be called outside safepoints. 394 // 395 // * They should both be called without holding the Heap_lock. 396 // 397 // * All allocation requests for new TLABs should go to 398 // allocate_new_tlab(). 399 // 400 // * All non-TLAB allocation requests should go to mem_allocate(). 401 // 402 // * If either call cannot satisfy the allocation request using the 403 // current allocating region, they will try to get a new one. If 404 // this fails, they will attempt to do an evacuation pause and 405 // retry the allocation. 406 // 407 // * If all allocation attempts fail, even after trying to schedule 408 // an evacuation pause, allocate_new_tlab() will return NULL, 409 // whereas mem_allocate() will attempt a heap expansion and/or 410 // schedule a Full GC. 411 // 412 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 413 // should never be called with word_size being humongous. All 414 // humongous allocation requests should go to mem_allocate() which 415 // will satisfy them with a special path. 416 417 virtual HeapWord* allocate_new_tlab(size_t min_size, 418 size_t requested_size, 419 size_t* actual_size); 420 421 virtual HeapWord* mem_allocate(size_t word_size, 422 bool* gc_overhead_limit_was_exceeded); 423 424 // First-level mutator allocation attempt: try to allocate out of 425 // the mutator alloc region without taking the Heap_lock. This 426 // should only be used for non-humongous allocations. 427 inline HeapWord* attempt_allocation(size_t min_word_size, 428 size_t desired_word_size, 429 size_t* actual_word_size); 430 431 // Second-level mutator allocation attempt: take the Heap_lock and 432 // retry the allocation attempt, potentially scheduling a GC 433 // pause. This should only be used for non-humongous allocations. 434 HeapWord* attempt_allocation_slow(size_t word_size); 435 436 // Takes the Heap_lock and attempts a humongous allocation. It can 437 // potentially schedule a GC pause. 438 HeapWord* attempt_allocation_humongous(size_t word_size); 439 440 // Allocation attempt that should be called during safepoints (e.g., 441 // at the end of a successful GC). expect_null_mutator_alloc_region 442 // specifies whether the mutator alloc region is expected to be NULL 443 // or not. 444 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 445 bool expect_null_mutator_alloc_region); 446 447 // These methods are the "callbacks" from the G1AllocRegion class. 448 449 // For mutator alloc regions. 450 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 451 void retire_mutator_alloc_region(HeapRegion* alloc_region, 452 size_t allocated_bytes); 453 454 // For GC alloc regions. 455 bool has_more_regions(InCSetState dest); 456 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 457 void retire_gc_alloc_region(HeapRegion* alloc_region, 458 size_t allocated_bytes, InCSetState dest); 459 460 // - if explicit_gc is true, the GC is for a System.gc() etc, 461 // otherwise it's for a failed allocation. 462 // - if clear_all_soft_refs is true, all soft references should be 463 // cleared during the GC. 464 // - it returns false if it is unable to do the collection due to the 465 // GC locker being active, true otherwise. 466 bool do_full_collection(bool explicit_gc, 467 bool clear_all_soft_refs); 468 469 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 470 virtual void do_full_collection(bool clear_all_soft_refs); 471 472 // Callback from VM_G1CollectForAllocation operation. 473 // This function does everything necessary/possible to satisfy a 474 // failed allocation request (including collection, expansion, etc.) 475 HeapWord* satisfy_failed_allocation(size_t word_size, 476 bool* succeeded); 477 // Internal helpers used during full GC to split it up to 478 // increase readability. 479 void abort_concurrent_cycle(); 480 void verify_before_full_collection(bool explicit_gc); 481 void prepare_heap_for_full_collection(); 482 void prepare_heap_for_mutators(); 483 void abort_refinement(); 484 void verify_after_full_collection(); 485 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 486 487 // Helper method for satisfy_failed_allocation() 488 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 489 bool do_gc, 490 bool clear_all_soft_refs, 491 bool expect_null_mutator_alloc_region, 492 bool* gc_succeeded); 493 494 // Attempting to expand the heap sufficiently 495 // to support an allocation of the given "word_size". If 496 // successful, perform the allocation and return the address of the 497 // allocated block, or else "NULL". 498 HeapWord* expand_and_allocate(size_t word_size); 499 500 // Process any reference objects discovered. 501 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 502 503 // If during an initial mark pause we may install a pending list head which is not 504 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking 505 // to discover. 506 void make_pending_list_reachable(); 507 508 // Merges the information gathered on a per-thread basis for all worker threads 509 // during GC into global variables. 510 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 511 public: 512 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 513 514 WorkGang* workers() const { return _workers; } 515 516 G1Allocator* allocator() { 517 return _allocator; 518 } 519 520 G1HeapVerifier* verifier() { 521 return _verifier; 522 } 523 524 G1MonitoringSupport* g1mm() { 525 assert(_g1mm != NULL, "should have been initialized"); 526 return _g1mm; 527 } 528 529 void resize_heap_if_necessary(); 530 531 // Expand the garbage-first heap by at least the given size (in bytes!). 532 // Returns true if the heap was expanded by the requested amount; 533 // false otherwise. 534 // (Rounds up to a HeapRegion boundary.) 535 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 536 537 // Returns the PLAB statistics for a given destination. 538 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 539 540 // Determines PLAB size for a given destination. 541 inline size_t desired_plab_sz(InCSetState dest); 542 543 // Do anything common to GC's. 544 void gc_prologue(bool full); 545 void gc_epilogue(bool full); 546 547 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 548 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 549 550 // Modify the reclaim candidate set and test for presence. 551 // These are only valid for starts_humongous regions. 552 inline void set_humongous_reclaim_candidate(uint region, bool value); 553 inline bool is_humongous_reclaim_candidate(uint region); 554 555 // Remove from the reclaim candidate set. Also remove from the 556 // collection set so that later encounters avoid the slow path. 557 inline void set_humongous_is_live(oop obj); 558 559 // Register the given region to be part of the collection set. 560 inline void register_humongous_region_with_cset(uint index); 561 // Register regions with humongous objects (actually on the start region) in 562 // the in_cset_fast_test table. 563 void register_humongous_regions_with_cset(); 564 // We register a region with the fast "in collection set" test. We 565 // simply set to true the array slot corresponding to this region. 566 void register_young_region_with_cset(HeapRegion* r) { 567 _in_cset_fast_test.set_in_young(r->hrm_index()); 568 } 569 void register_old_region_with_cset(HeapRegion* r) { 570 _in_cset_fast_test.set_in_old(r->hrm_index()); 571 } 572 void register_optional_region_with_cset(HeapRegion* r) { 573 _in_cset_fast_test.set_optional(r->hrm_index()); 574 } 575 void clear_in_cset(const HeapRegion* hr) { 576 _in_cset_fast_test.clear(hr); 577 } 578 579 void clear_cset_fast_test() { 580 _in_cset_fast_test.clear(); 581 } 582 583 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 584 585 // This is called at the start of either a concurrent cycle or a Full 586 // GC to update the number of old marking cycles started. 587 void increment_old_marking_cycles_started(); 588 589 // This is called at the end of either a concurrent cycle or a Full 590 // GC to update the number of old marking cycles completed. Those two 591 // can happen in a nested fashion, i.e., we start a concurrent 592 // cycle, a Full GC happens half-way through it which ends first, 593 // and then the cycle notices that a Full GC happened and ends 594 // too. The concurrent parameter is a boolean to help us do a bit 595 // tighter consistency checking in the method. If concurrent is 596 // false, the caller is the inner caller in the nesting (i.e., the 597 // Full GC). If concurrent is true, the caller is the outer caller 598 // in this nesting (i.e., the concurrent cycle). Further nesting is 599 // not currently supported. The end of this call also notifies 600 // the FullGCCount_lock in case a Java thread is waiting for a full 601 // GC to happen (e.g., it called System.gc() with 602 // +ExplicitGCInvokesConcurrent). 603 void increment_old_marking_cycles_completed(bool concurrent); 604 605 uint old_marking_cycles_completed() { 606 return _old_marking_cycles_completed; 607 } 608 609 G1HRPrinter* hr_printer() { return &_hr_printer; } 610 611 // Allocates a new heap region instance. 612 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 613 614 // Allocate the highest free region in the reserved heap. This will commit 615 // regions as necessary. 616 HeapRegion* alloc_highest_free_region(); 617 618 // Frees a non-humongous region by initializing its contents and 619 // adding it to the free list that's passed as a parameter (this is 620 // usually a local list which will be appended to the master free 621 // list later). The used bytes of freed regions are accumulated in 622 // pre_used. If skip_remset is true, the region's RSet will not be freed 623 // up. If skip_hot_card_cache is true, the region's hot card cache will not 624 // be freed up. The assumption is that this will be done later. 625 // The locked parameter indicates if the caller has already taken 626 // care of proper synchronization. This may allow some optimizations. 627 void free_region(HeapRegion* hr, 628 FreeRegionList* free_list, 629 bool skip_remset, 630 bool skip_hot_card_cache = false, 631 bool locked = false); 632 633 // It dirties the cards that cover the block so that the post 634 // write barrier never queues anything when updating objects on this 635 // block. It is assumed (and in fact we assert) that the block 636 // belongs to a young region. 637 inline void dirty_young_block(HeapWord* start, size_t word_size); 638 639 // Frees a humongous region by collapsing it into individual regions 640 // and calling free_region() for each of them. The freed regions 641 // will be added to the free list that's passed as a parameter (this 642 // is usually a local list which will be appended to the master free 643 // list later). 644 // The method assumes that only a single thread is ever calling 645 // this for a particular region at once. 646 void free_humongous_region(HeapRegion* hr, 647 FreeRegionList* free_list); 648 649 // Facility for allocating in 'archive' regions in high heap memory and 650 // recording the allocated ranges. These should all be called from the 651 // VM thread at safepoints, without the heap lock held. They can be used 652 // to create and archive a set of heap regions which can be mapped at the 653 // same fixed addresses in a subsequent JVM invocation. 654 void begin_archive_alloc_range(bool open = false); 655 656 // Check if the requested size would be too large for an archive allocation. 657 bool is_archive_alloc_too_large(size_t word_size); 658 659 // Allocate memory of the requested size from the archive region. This will 660 // return NULL if the size is too large or if no memory is available. It 661 // does not trigger a garbage collection. 662 HeapWord* archive_mem_allocate(size_t word_size); 663 664 // Optionally aligns the end address and returns the allocated ranges in 665 // an array of MemRegions in order of ascending addresses. 666 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 667 size_t end_alignment_in_bytes = 0); 668 669 // Facility for allocating a fixed range within the heap and marking 670 // the containing regions as 'archive'. For use at JVM init time, when the 671 // caller may mmap archived heap data at the specified range(s). 672 // Verify that the MemRegions specified in the argument array are within the 673 // reserved heap. 674 bool check_archive_addresses(MemRegion* range, size_t count); 675 676 // Commit the appropriate G1 regions containing the specified MemRegions 677 // and mark them as 'archive' regions. The regions in the array must be 678 // non-overlapping and in order of ascending address. 679 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 680 681 // Insert any required filler objects in the G1 regions around the specified 682 // ranges to make the regions parseable. This must be called after 683 // alloc_archive_regions, and after class loading has occurred. 684 void fill_archive_regions(MemRegion* range, size_t count); 685 686 // For each of the specified MemRegions, uncommit the containing G1 regions 687 // which had been allocated by alloc_archive_regions. This should be called 688 // rather than fill_archive_regions at JVM init time if the archive file 689 // mapping failed, with the same non-overlapping and sorted MemRegion array. 690 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open); 691 692 oop materialize_archived_object(oop obj); 693 694 private: 695 696 // Shrink the garbage-first heap by at most the given size (in bytes!). 697 // (Rounds down to a HeapRegion boundary.) 698 void shrink(size_t expand_bytes); 699 void shrink_helper(size_t expand_bytes); 700 701 #if TASKQUEUE_STATS 702 static void print_taskqueue_stats_hdr(outputStream* const st); 703 void print_taskqueue_stats() const; 704 void reset_taskqueue_stats(); 705 #endif // TASKQUEUE_STATS 706 707 // Schedule the VM operation that will do an evacuation pause to 708 // satisfy an allocation request of word_size. *succeeded will 709 // return whether the VM operation was successful (it did do an 710 // evacuation pause) or not (another thread beat us to it or the GC 711 // locker was active). Given that we should not be holding the 712 // Heap_lock when we enter this method, we will pass the 713 // gc_count_before (i.e., total_collections()) as a parameter since 714 // it has to be read while holding the Heap_lock. Currently, both 715 // methods that call do_collection_pause() release the Heap_lock 716 // before the call, so it's easy to read gc_count_before just before. 717 HeapWord* do_collection_pause(size_t word_size, 718 uint gc_count_before, 719 bool* succeeded, 720 GCCause::Cause gc_cause); 721 722 void wait_for_root_region_scanning(); 723 724 // The guts of the incremental collection pause, executed by the vm 725 // thread. It returns false if it is unable to do the collection due 726 // to the GC locker being active, true otherwise 727 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 728 729 // Actually do the work of evacuating the collection set. 730 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states); 731 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states); 732 void evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset); 733 734 void pre_evacuate_collection_set(); 735 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 736 737 // Print the header for the per-thread termination statistics. 738 static void print_termination_stats_hdr(); 739 // Print actual per-thread termination statistics. 740 void print_termination_stats(uint worker_id, 741 double elapsed_ms, 742 double strong_roots_ms, 743 double term_ms, 744 size_t term_attempts, 745 size_t alloc_buffer_waste, 746 size_t undo_waste) const; 747 // Update object copying statistics. 748 void record_obj_copy_mem_stats(); 749 750 // The hot card cache for remembered set insertion optimization. 751 G1HotCardCache* _hot_card_cache; 752 753 // The g1 remembered set of the heap. 754 G1RemSet* _g1_rem_set; 755 756 // A set of cards that cover the objects for which the Rsets should be updated 757 // concurrently after the collection. 758 DirtyCardQueueSet _dirty_card_queue_set; 759 760 // After a collection pause, convert the regions in the collection set into free 761 // regions. 762 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 763 764 // Abandon the current collection set without recording policy 765 // statistics or updating free lists. 766 void abandon_collection_set(G1CollectionSet* collection_set); 767 768 // The concurrent marker (and the thread it runs in.) 769 G1ConcurrentMark* _cm; 770 G1ConcurrentMarkThread* _cm_thread; 771 772 // The concurrent refiner. 773 G1ConcurrentRefine* _cr; 774 775 // The parallel task queues 776 RefToScanQueueSet *_task_queues; 777 778 // True iff a evacuation has failed in the current collection. 779 bool _evacuation_failed; 780 781 EvacuationFailedInfo* _evacuation_failed_info_array; 782 783 // Failed evacuations cause some logical from-space objects to have 784 // forwarding pointers to themselves. Reset them. 785 void remove_self_forwarding_pointers(); 786 787 // Restore the objects in the regions in the collection set after an 788 // evacuation failure. 789 void restore_after_evac_failure(); 790 791 PreservedMarksSet _preserved_marks_set; 792 793 // Preserve the mark of "obj", if necessary, in preparation for its mark 794 // word being overwritten with a self-forwarding-pointer. 795 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 796 797 #ifndef PRODUCT 798 // Support for forcing evacuation failures. Analogous to 799 // PromotionFailureALot for the other collectors. 800 801 // Records whether G1EvacuationFailureALot should be in effect 802 // for the current GC 803 bool _evacuation_failure_alot_for_current_gc; 804 805 // Used to record the GC number for interval checking when 806 // determining whether G1EvaucationFailureALot is in effect 807 // for the current GC. 808 size_t _evacuation_failure_alot_gc_number; 809 810 // Count of the number of evacuations between failures. 811 volatile size_t _evacuation_failure_alot_count; 812 813 // Set whether G1EvacuationFailureALot should be in effect 814 // for the current GC (based upon the type of GC and which 815 // command line flags are set); 816 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, 817 bool during_initial_mark, 818 bool mark_or_rebuild_in_progress); 819 820 inline void set_evacuation_failure_alot_for_current_gc(); 821 822 // Return true if it's time to cause an evacuation failure. 823 inline bool evacuation_should_fail(); 824 825 // Reset the G1EvacuationFailureALot counters. Should be called at 826 // the end of an evacuation pause in which an evacuation failure occurred. 827 inline void reset_evacuation_should_fail(); 828 #endif // !PRODUCT 829 830 // ("Weak") Reference processing support. 831 // 832 // G1 has 2 instances of the reference processor class. One 833 // (_ref_processor_cm) handles reference object discovery 834 // and subsequent processing during concurrent marking cycles. 835 // 836 // The other (_ref_processor_stw) handles reference object 837 // discovery and processing during full GCs and incremental 838 // evacuation pauses. 839 // 840 // During an incremental pause, reference discovery will be 841 // temporarily disabled for _ref_processor_cm and will be 842 // enabled for _ref_processor_stw. At the end of the evacuation 843 // pause references discovered by _ref_processor_stw will be 844 // processed and discovery will be disabled. The previous 845 // setting for reference object discovery for _ref_processor_cm 846 // will be re-instated. 847 // 848 // At the start of marking: 849 // * Discovery by the CM ref processor is verified to be inactive 850 // and it's discovered lists are empty. 851 // * Discovery by the CM ref processor is then enabled. 852 // 853 // At the end of marking: 854 // * Any references on the CM ref processor's discovered 855 // lists are processed (possibly MT). 856 // 857 // At the start of full GC we: 858 // * Disable discovery by the CM ref processor and 859 // empty CM ref processor's discovered lists 860 // (without processing any entries). 861 // * Verify that the STW ref processor is inactive and it's 862 // discovered lists are empty. 863 // * Temporarily set STW ref processor discovery as single threaded. 864 // * Temporarily clear the STW ref processor's _is_alive_non_header 865 // field. 866 // * Finally enable discovery by the STW ref processor. 867 // 868 // The STW ref processor is used to record any discovered 869 // references during the full GC. 870 // 871 // At the end of a full GC we: 872 // * Enqueue any reference objects discovered by the STW ref processor 873 // that have non-live referents. This has the side-effect of 874 // making the STW ref processor inactive by disabling discovery. 875 // * Verify that the CM ref processor is still inactive 876 // and no references have been placed on it's discovered 877 // lists (also checked as a precondition during initial marking). 878 879 // The (stw) reference processor... 880 ReferenceProcessor* _ref_processor_stw; 881 882 // During reference object discovery, the _is_alive_non_header 883 // closure (if non-null) is applied to the referent object to 884 // determine whether the referent is live. If so then the 885 // reference object does not need to be 'discovered' and can 886 // be treated as a regular oop. This has the benefit of reducing 887 // the number of 'discovered' reference objects that need to 888 // be processed. 889 // 890 // Instance of the is_alive closure for embedding into the 891 // STW reference processor as the _is_alive_non_header field. 892 // Supplying a value for the _is_alive_non_header field is 893 // optional but doing so prevents unnecessary additions to 894 // the discovered lists during reference discovery. 895 G1STWIsAliveClosure _is_alive_closure_stw; 896 897 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 898 899 // The (concurrent marking) reference processor... 900 ReferenceProcessor* _ref_processor_cm; 901 902 // Instance of the concurrent mark is_alive closure for embedding 903 // into the Concurrent Marking reference processor as the 904 // _is_alive_non_header field. Supplying a value for the 905 // _is_alive_non_header field is optional but doing so prevents 906 // unnecessary additions to the discovered lists during reference 907 // discovery. 908 G1CMIsAliveClosure _is_alive_closure_cm; 909 910 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 911 public: 912 913 RefToScanQueue *task_queue(uint i) const; 914 915 uint num_task_queues() const; 916 917 // A set of cards where updates happened during the GC 918 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 919 920 // Create a G1CollectedHeap with the specified policy. 921 // Must call the initialize method afterwards. 922 // May not return if something goes wrong. 923 G1CollectedHeap(G1CollectorPolicy* policy); 924 925 private: 926 jint initialize_concurrent_refinement(); 927 jint initialize_young_gen_sampling_thread(); 928 public: 929 // Initialize the G1CollectedHeap to have the initial and 930 // maximum sizes and remembered and barrier sets 931 // specified by the policy object. 932 jint initialize(); 933 934 virtual void stop(); 935 virtual void safepoint_synchronize_begin(); 936 virtual void safepoint_synchronize_end(); 937 938 // Return the (conservative) maximum heap alignment for any G1 heap 939 static size_t conservative_max_heap_alignment(); 940 941 // Does operations required after initialization has been done. 942 void post_initialize(); 943 944 // Initialize weak reference processing. 945 void ref_processing_init(); 946 947 virtual Name kind() const { 948 return CollectedHeap::G1; 949 } 950 951 virtual const char* name() const { 952 return "G1"; 953 } 954 955 const G1CollectorState* collector_state() const { return &_collector_state; } 956 G1CollectorState* collector_state() { return &_collector_state; } 957 958 // The current policy object for the collector. 959 G1Policy* g1_policy() const { return _g1_policy; } 960 961 const G1CollectionSet* collection_set() const { return &_collection_set; } 962 G1CollectionSet* collection_set() { return &_collection_set; } 963 964 virtual CollectorPolicy* collector_policy() const; 965 966 virtual SoftRefPolicy* soft_ref_policy(); 967 968 virtual void initialize_serviceability(); 969 virtual MemoryUsage memory_usage(); 970 virtual GrowableArray<GCMemoryManager*> memory_managers(); 971 virtual GrowableArray<MemoryPool*> memory_pools(); 972 973 // The rem set and barrier set. 974 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 975 976 // Try to minimize the remembered set. 977 void scrub_rem_set(); 978 979 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 980 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 981 982 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 983 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 984 985 // The shared block offset table array. 986 G1BlockOffsetTable* bot() const { return _bot; } 987 988 // Reference Processing accessors 989 990 // The STW reference processor.... 991 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 992 993 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 994 995 // The Concurrent Marking reference processor... 996 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 997 998 size_t unused_committed_regions_in_bytes() const; 999 virtual size_t capacity() const; 1000 virtual size_t used() const; 1001 // This should be called when we're not holding the heap lock. The 1002 // result might be a bit inaccurate. 1003 size_t used_unlocked() const; 1004 size_t recalculate_used() const; 1005 1006 // These virtual functions do the actual allocation. 1007 // Some heaps may offer a contiguous region for shared non-blocking 1008 // allocation, via inlined code (by exporting the address of the top and 1009 // end fields defining the extent of the contiguous allocation region.) 1010 // But G1CollectedHeap doesn't yet support this. 1011 1012 virtual bool is_maximal_no_gc() const { 1013 return _hrm.available() == 0; 1014 } 1015 1016 // Returns whether there are any regions left in the heap for allocation. 1017 bool has_regions_left_for_allocation() const { 1018 return !is_maximal_no_gc() || num_free_regions() != 0; 1019 } 1020 1021 // The current number of regions in the heap. 1022 uint num_regions() const { return _hrm.length(); } 1023 1024 // The max number of regions in the heap. 1025 uint max_regions() const { return _hrm.max_length(); } 1026 1027 // The number of regions that are completely free. 1028 uint num_free_regions() const { return _hrm.num_free_regions(); } 1029 1030 MemoryUsage get_auxiliary_data_memory_usage() const { 1031 return _hrm.get_auxiliary_data_memory_usage(); 1032 } 1033 1034 // The number of regions that are not completely free. 1035 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1036 1037 #ifdef ASSERT 1038 bool is_on_master_free_list(HeapRegion* hr) { 1039 return _hrm.is_free(hr); 1040 } 1041 #endif // ASSERT 1042 1043 inline void old_set_add(HeapRegion* hr); 1044 inline void old_set_remove(HeapRegion* hr); 1045 1046 inline void archive_set_add(HeapRegion* hr); 1047 1048 size_t non_young_capacity_bytes() { 1049 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1050 } 1051 1052 // Determine whether the given region is one that we are using as an 1053 // old GC alloc region. 1054 bool is_old_gc_alloc_region(HeapRegion* hr); 1055 1056 // Perform a collection of the heap; intended for use in implementing 1057 // "System.gc". This probably implies as full a collection as the 1058 // "CollectedHeap" supports. 1059 virtual void collect(GCCause::Cause cause); 1060 1061 // True iff an evacuation has failed in the most-recent collection. 1062 bool evacuation_failed() { return _evacuation_failed; } 1063 1064 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1065 void prepend_to_freelist(FreeRegionList* list); 1066 void decrement_summary_bytes(size_t bytes); 1067 1068 virtual bool is_in(const void* p) const; 1069 #ifdef ASSERT 1070 // Returns whether p is in one of the available areas of the heap. Slow but 1071 // extensive version. 1072 bool is_in_exact(const void* p) const; 1073 #endif 1074 1075 // Return "TRUE" iff the given object address is within the collection 1076 // set. Assumes that the reference points into the heap. 1077 inline bool is_in_cset(const HeapRegion *hr); 1078 inline bool is_in_cset(oop obj); 1079 inline bool is_in_cset(HeapWord* addr); 1080 1081 inline bool is_in_cset_or_humongous(const oop obj); 1082 1083 private: 1084 // This array is used for a quick test on whether a reference points into 1085 // the collection set or not. Each of the array's elements denotes whether the 1086 // corresponding region is in the collection set or not. 1087 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1088 1089 public: 1090 1091 inline InCSetState in_cset_state(const oop obj); 1092 1093 // Return "TRUE" iff the given object address is in the reserved 1094 // region of g1. 1095 bool is_in_g1_reserved(const void* p) const { 1096 return _hrm.reserved().contains(p); 1097 } 1098 1099 // Returns a MemRegion that corresponds to the space that has been 1100 // reserved for the heap 1101 MemRegion g1_reserved() const { 1102 return _hrm.reserved(); 1103 } 1104 1105 virtual bool is_in_closed_subset(const void* p) const; 1106 1107 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1108 1109 G1CardTable* card_table() const { 1110 return _card_table; 1111 } 1112 1113 // Iteration functions. 1114 1115 // Iterate over all objects, calling "cl.do_object" on each. 1116 virtual void object_iterate(ObjectClosure* cl); 1117 1118 virtual void safe_object_iterate(ObjectClosure* cl) { 1119 object_iterate(cl); 1120 } 1121 1122 // Iterate over heap regions, in address order, terminating the 1123 // iteration early if the "do_heap_region" method returns "true". 1124 void heap_region_iterate(HeapRegionClosure* blk) const; 1125 1126 // Return the region with the given index. It assumes the index is valid. 1127 inline HeapRegion* region_at(uint index) const; 1128 inline HeapRegion* region_at_or_null(uint index) const; 1129 1130 // Return the next region (by index) that is part of the same 1131 // humongous object that hr is part of. 1132 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1133 1134 // Calculate the region index of the given address. Given address must be 1135 // within the heap. 1136 inline uint addr_to_region(HeapWord* addr) const; 1137 1138 inline HeapWord* bottom_addr_for_region(uint index) const; 1139 1140 // Two functions to iterate over the heap regions in parallel. Threads 1141 // compete using the HeapRegionClaimer to claim the regions before 1142 // applying the closure on them. 1143 // The _from_worker_offset version uses the HeapRegionClaimer and 1144 // the worker id to calculate a start offset to prevent all workers to 1145 // start from the point. 1146 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1147 HeapRegionClaimer* hrclaimer, 1148 uint worker_id) const; 1149 1150 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1151 HeapRegionClaimer* hrclaimer) const; 1152 1153 // Iterate over the regions (if any) in the current collection set. 1154 void collection_set_iterate(HeapRegionClosure* blk); 1155 1156 // Iterate over the regions (if any) in the current collection set. Starts the 1157 // iteration over the entire collection set so that the start regions of a given 1158 // worker id over the set active_workers are evenly spread across the set of 1159 // collection set regions. 1160 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1161 1162 // Returns the HeapRegion that contains addr. addr must not be NULL. 1163 template <class T> 1164 inline HeapRegion* heap_region_containing(const T addr) const; 1165 1166 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted 1167 // region. addr must not be NULL. 1168 template <class T> 1169 inline HeapRegion* heap_region_containing_or_null(const T addr) const; 1170 1171 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1172 // each address in the (reserved) heap is a member of exactly 1173 // one block. The defining characteristic of a block is that it is 1174 // possible to find its size, and thus to progress forward to the next 1175 // block. (Blocks may be of different sizes.) Thus, blocks may 1176 // represent Java objects, or they might be free blocks in a 1177 // free-list-based heap (or subheap), as long as the two kinds are 1178 // distinguishable and the size of each is determinable. 1179 1180 // Returns the address of the start of the "block" that contains the 1181 // address "addr". We say "blocks" instead of "object" since some heaps 1182 // may not pack objects densely; a chunk may either be an object or a 1183 // non-object. 1184 virtual HeapWord* block_start(const void* addr) const; 1185 1186 // Requires "addr" to be the start of a chunk, and returns its size. 1187 // "addr + size" is required to be the start of a new chunk, or the end 1188 // of the active area of the heap. 1189 virtual size_t block_size(const HeapWord* addr) const; 1190 1191 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1192 // the block is an object. 1193 virtual bool block_is_obj(const HeapWord* addr) const; 1194 1195 // Section on thread-local allocation buffers (TLABs) 1196 // See CollectedHeap for semantics. 1197 1198 bool supports_tlab_allocation() const; 1199 size_t tlab_capacity(Thread* ignored) const; 1200 size_t tlab_used(Thread* ignored) const; 1201 size_t max_tlab_size() const; 1202 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1203 1204 inline bool is_in_young(const oop obj); 1205 1206 // Returns "true" iff the given word_size is "very large". 1207 static bool is_humongous(size_t word_size) { 1208 // Note this has to be strictly greater-than as the TLABs 1209 // are capped at the humongous threshold and we want to 1210 // ensure that we don't try to allocate a TLAB as 1211 // humongous and that we don't allocate a humongous 1212 // object in a TLAB. 1213 return word_size > _humongous_object_threshold_in_words; 1214 } 1215 1216 // Returns the humongous threshold for a specific region size 1217 static size_t humongous_threshold_for(size_t region_size) { 1218 return (region_size / 2); 1219 } 1220 1221 // Returns the number of regions the humongous object of the given word size 1222 // requires. 1223 static size_t humongous_obj_size_in_regions(size_t word_size); 1224 1225 // Print the maximum heap capacity. 1226 virtual size_t max_capacity() const; 1227 1228 virtual jlong millis_since_last_gc(); 1229 1230 1231 // Convenience function to be used in situations where the heap type can be 1232 // asserted to be this type. 1233 static G1CollectedHeap* heap(); 1234 1235 void set_region_short_lived_locked(HeapRegion* hr); 1236 // add appropriate methods for any other surv rate groups 1237 1238 const G1SurvivorRegions* survivor() const { return &_survivor; } 1239 1240 uint eden_regions_count() const { return _eden.length(); } 1241 uint survivor_regions_count() const { return _survivor.length(); } 1242 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1243 uint old_regions_count() const { return _old_set.length(); } 1244 uint archive_regions_count() const { return _archive_set.length(); } 1245 uint humongous_regions_count() const { return _humongous_set.length(); } 1246 1247 #ifdef ASSERT 1248 bool check_young_list_empty(); 1249 #endif 1250 1251 // *** Stuff related to concurrent marking. It's not clear to me that so 1252 // many of these need to be public. 1253 1254 // The functions below are helper functions that a subclass of 1255 // "CollectedHeap" can use in the implementation of its virtual 1256 // functions. 1257 // This performs a concurrent marking of the live objects in a 1258 // bitmap off to the side. 1259 void do_concurrent_mark(); 1260 1261 bool is_marked_next(oop obj) const; 1262 1263 // Determine if an object is dead, given the object and also 1264 // the region to which the object belongs. An object is dead 1265 // iff a) it was not allocated since the last mark, b) it 1266 // is not marked, and c) it is not in an archive region. 1267 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1268 return 1269 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1270 !hr->is_archive(); 1271 } 1272 1273 // This function returns true when an object has been 1274 // around since the previous marking and hasn't yet 1275 // been marked during this marking, and is not in an archive region. 1276 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1277 return 1278 !hr->obj_allocated_since_next_marking(obj) && 1279 !is_marked_next(obj) && 1280 !hr->is_archive(); 1281 } 1282 1283 // Determine if an object is dead, given only the object itself. 1284 // This will find the region to which the object belongs and 1285 // then call the region version of the same function. 1286 1287 // Added if it is NULL it isn't dead. 1288 1289 inline bool is_obj_dead(const oop obj) const; 1290 1291 inline bool is_obj_ill(const oop obj) const; 1292 1293 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1294 inline bool is_obj_dead_full(const oop obj) const; 1295 1296 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1297 1298 // Refinement 1299 1300 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1301 1302 // Optimized nmethod scanning support routines 1303 1304 // Is an oop scavengeable 1305 virtual bool is_scavengable(oop obj); 1306 1307 // Register the given nmethod with the G1 heap. 1308 virtual void register_nmethod(nmethod* nm); 1309 1310 // Unregister the given nmethod from the G1 heap. 1311 virtual void unregister_nmethod(nmethod* nm); 1312 1313 // Free up superfluous code root memory. 1314 void purge_code_root_memory(); 1315 1316 // Rebuild the strong code root lists for each region 1317 // after a full GC. 1318 void rebuild_strong_code_roots(); 1319 1320 // Partial cleaning used when class unloading is disabled. 1321 // Let the caller choose what structures to clean out: 1322 // - StringTable 1323 // - StringDeduplication structures 1324 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_string_dedup); 1325 1326 // Complete cleaning used when class unloading is enabled. 1327 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1328 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1329 1330 // Redirty logged cards in the refinement queue. 1331 void redirty_logged_cards(); 1332 // Verification 1333 1334 // Deduplicate the string 1335 virtual void deduplicate_string(oop str); 1336 1337 // Perform any cleanup actions necessary before allowing a verification. 1338 virtual void prepare_for_verify(); 1339 1340 // Perform verification. 1341 1342 // vo == UsePrevMarking -> use "prev" marking information, 1343 // vo == UseNextMarking -> use "next" marking information 1344 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1345 // 1346 // NOTE: Only the "prev" marking information is guaranteed to be 1347 // consistent most of the time, so most calls to this should use 1348 // vo == UsePrevMarking. 1349 // Currently, there is only one case where this is called with 1350 // vo == UseNextMarking, which is to verify the "next" marking 1351 // information at the end of remark. 1352 // Currently there is only one place where this is called with 1353 // vo == UseFullMarking, which is to verify the marking during a 1354 // full GC. 1355 void verify(VerifyOption vo); 1356 1357 // WhiteBox testing support. 1358 virtual bool supports_concurrent_phase_control() const; 1359 virtual const char* const* concurrent_phases() const; 1360 virtual bool request_concurrent_phase(const char* phase); 1361 1362 virtual WorkGang* get_safepoint_workers() { return _workers; } 1363 1364 // The methods below are here for convenience and dispatch the 1365 // appropriate method depending on value of the given VerifyOption 1366 // parameter. The values for that parameter, and their meanings, 1367 // are the same as those above. 1368 1369 bool is_obj_dead_cond(const oop obj, 1370 const HeapRegion* hr, 1371 const VerifyOption vo) const; 1372 1373 bool is_obj_dead_cond(const oop obj, 1374 const VerifyOption vo) const; 1375 1376 G1HeapSummary create_g1_heap_summary(); 1377 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1378 1379 // Printing 1380 private: 1381 void print_heap_regions() const; 1382 void print_regions_on(outputStream* st) const; 1383 1384 public: 1385 virtual void print_on(outputStream* st) const; 1386 virtual void print_extended_on(outputStream* st) const; 1387 virtual void print_on_error(outputStream* st) const; 1388 1389 virtual void print_gc_threads_on(outputStream* st) const; 1390 virtual void gc_threads_do(ThreadClosure* tc) const; 1391 1392 // Override 1393 void print_tracing_info() const; 1394 1395 // The following two methods are helpful for debugging RSet issues. 1396 void print_cset_rsets() PRODUCT_RETURN; 1397 void print_all_rsets() PRODUCT_RETURN; 1398 1399 size_t pending_card_num(); 1400 }; 1401 1402 class G1ParEvacuateFollowersClosure : public VoidClosure { 1403 private: 1404 double _start_term; 1405 double _term_time; 1406 size_t _term_attempts; 1407 1408 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1409 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1410 protected: 1411 G1CollectedHeap* _g1h; 1412 G1ParScanThreadState* _par_scan_state; 1413 RefToScanQueueSet* _queues; 1414 ParallelTaskTerminator* _terminator; 1415 G1GCPhaseTimes::GCParPhases _phase; 1416 1417 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1418 RefToScanQueueSet* queues() { return _queues; } 1419 ParallelTaskTerminator* terminator() { return _terminator; } 1420 1421 public: 1422 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1423 G1ParScanThreadState* par_scan_state, 1424 RefToScanQueueSet* queues, 1425 ParallelTaskTerminator* terminator, 1426 G1GCPhaseTimes::GCParPhases phase) 1427 : _start_term(0.0), _term_time(0.0), _term_attempts(0), 1428 _g1h(g1h), _par_scan_state(par_scan_state), 1429 _queues(queues), _terminator(terminator), _phase(phase) {} 1430 1431 void do_void(); 1432 1433 double term_time() const { return _term_time; } 1434 size_t term_attempts() const { return _term_attempts; } 1435 1436 private: 1437 inline bool offer_termination(); 1438 }; 1439 1440 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP