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/g1AllocationContext.hpp" 30 #include "gc/g1/g1BarrierSet.hpp" 31 #include "gc/g1/g1BiasedArray.hpp" 32 #include "gc/g1/g1CardTable.hpp" 33 #include "gc/g1/g1CollectionSet.hpp" 34 #include "gc/g1/g1CollectorState.hpp" 35 #include "gc/g1/g1ConcurrentMark.hpp" 36 #include "gc/g1/g1EdenRegions.hpp" 37 #include "gc/g1/g1EvacFailure.hpp" 38 #include "gc/g1/g1EvacStats.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 "services/memoryManager.hpp" 56 #include "utilities/stack.hpp" 57 58 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 59 // It uses the "Garbage First" heap organization and algorithm, which 60 // may combine concurrent marking with parallel, incremental compaction of 61 // heap subsets that will yield large amounts of garbage. 62 63 // Forward declarations 64 class HeapRegion; 65 class HRRSCleanupTask; 66 class GenerationSpec; 67 class G1ParScanThreadState; 68 class G1ParScanThreadStateSet; 69 class G1ParScanThreadState; 70 class MemoryPool; 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 ConcurrentMarkThread; 84 class G1ConcurrentRefine; 85 class GenerationCounters; 86 class STWGCTimer; 87 class G1NewTracer; 88 class EvacuationFailedInfo; 89 class nmethod; 90 class Ticks; 91 class WorkGang; 92 class G1Allocator; 93 class G1ArchiveAllocator; 94 class G1FullGCScope; 95 class G1HeapVerifier; 96 class G1HeapSizingPolicy; 97 class G1HeapSummary; 98 class G1EvacSummary; 99 100 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 101 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 102 103 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 104 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 105 106 // The G1 STW is alive closure. 107 // An instance is embedded into the G1CH and used as the 108 // (optional) _is_alive_non_header closure in the STW 109 // reference processor. It is also extensively used during 110 // reference processing during STW evacuation pauses. 111 class G1STWIsAliveClosure: public BoolObjectClosure { 112 G1CollectedHeap* _g1; 113 public: 114 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 115 bool do_object_b(oop p); 116 }; 117 118 class G1RegionMappingChangedListener : public G1MappingChangedListener { 119 private: 120 void reset_from_card_cache(uint start_idx, size_t num_regions); 121 public: 122 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 123 }; 124 125 class G1CollectedHeap : public CollectedHeap { 126 friend class G1FreeCollectionSetTask; 127 friend class VM_CollectForMetadataAllocation; 128 friend class VM_G1CollectForAllocation; 129 friend class VM_G1CollectFull; 130 friend class VMStructs; 131 friend class MutatorAllocRegion; 132 friend class G1FullCollector; 133 friend class G1GCAllocRegion; 134 friend class G1HeapVerifier; 135 136 // Closures used in implementation. 137 friend class G1ParScanThreadState; 138 friend class G1ParScanThreadStateSet; 139 friend class G1ParTask; 140 friend class G1PLABAllocator; 141 friend class G1PrepareCompactClosure; 142 143 // Other related classes. 144 friend class HeapRegionClaimer; 145 146 // Testing classes. 147 friend class G1CheckCSetFastTableClosure; 148 149 private: 150 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 151 152 WorkGang* _workers; 153 G1CollectorPolicy* _collector_policy; 154 G1CardTable* _card_table; 155 156 SoftRefPolicy _soft_ref_policy; 157 158 GCMemoryManager _memory_manager; 159 GCMemoryManager _full_gc_memory_manager; 160 161 MemoryPool* _eden_pool; 162 MemoryPool* _survivor_pool; 163 MemoryPool* _old_pool; 164 165 static size_t _humongous_object_threshold_in_words; 166 167 // The secondary free list which contains regions that have been 168 // freed up during the cleanup process. This will be appended to 169 // the master free list when appropriate. 170 FreeRegionList _secondary_free_list; 171 172 // It keeps track of the old regions. 173 HeapRegionSet _old_set; 174 175 // It keeps track of the humongous regions. 176 HeapRegionSet _humongous_set; 177 178 virtual void initialize_serviceability(); 179 180 void eagerly_reclaim_humongous_regions(); 181 // Start a new incremental collection set for the next pause. 182 void start_new_collection_set(); 183 184 // The number of regions we could create by expansion. 185 uint _expansion_regions; 186 187 // The block offset table for the G1 heap. 188 G1BlockOffsetTable* _bot; 189 190 // Tears down the region sets / lists so that they are empty and the 191 // regions on the heap do not belong to a region set / list. The 192 // only exception is the humongous set which we leave unaltered. If 193 // free_list_only is true, it will only tear down the master free 194 // list. It is called before a Full GC (free_list_only == false) or 195 // before heap shrinking (free_list_only == true). 196 void tear_down_region_sets(bool free_list_only); 197 198 // Rebuilds the region sets / lists so that they are repopulated to 199 // reflect the contents of the heap. The only exception is the 200 // humongous set which was not torn down in the first place. If 201 // free_list_only is true, it will only rebuild the master free 202 // list. It is called after a Full GC (free_list_only == false) or 203 // after heap shrinking (free_list_only == true). 204 void rebuild_region_sets(bool free_list_only); 205 206 // Callback for region mapping changed events. 207 G1RegionMappingChangedListener _listener; 208 209 // The sequence of all heap regions in the heap. 210 HeapRegionManager _hrm; 211 212 // Manages all allocations with regions except humongous object allocations. 213 G1Allocator* _allocator; 214 215 // Manages all heap verification. 216 G1HeapVerifier* _verifier; 217 218 // Outside of GC pauses, the number of bytes used in all regions other 219 // than the current allocation region(s). 220 size_t _summary_bytes_used; 221 222 void increase_used(size_t bytes); 223 void decrease_used(size_t bytes); 224 225 void set_used(size_t bytes); 226 227 // Class that handles archive allocation ranges. 228 G1ArchiveAllocator* _archive_allocator; 229 230 // GC allocation statistics policy for survivors. 231 G1EvacStats _survivor_evac_stats; 232 233 // GC allocation statistics policy for tenured objects. 234 G1EvacStats _old_evac_stats; 235 236 // It specifies whether we should attempt to expand the heap after a 237 // region allocation failure. If heap expansion fails we set this to 238 // false so that we don't re-attempt the heap expansion (it's likely 239 // that subsequent expansion attempts will also fail if one fails). 240 // Currently, it is only consulted during GC and it's reset at the 241 // start of each GC. 242 bool _expand_heap_after_alloc_failure; 243 244 // Helper for monitoring and management support. 245 G1MonitoringSupport* _g1mm; 246 247 // Records whether the region at the given index is (still) a 248 // candidate for eager reclaim. Only valid for humongous start 249 // regions; other regions have unspecified values. Humongous start 250 // regions are initialized at start of collection pause, with 251 // candidates removed from the set as they are found reachable from 252 // roots or the young generation. 253 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 254 protected: 255 bool default_value() const { return false; } 256 public: 257 void clear() { G1BiasedMappedArray<bool>::clear(); } 258 void set_candidate(uint region, bool value) { 259 set_by_index(region, value); 260 } 261 bool is_candidate(uint region) { 262 return get_by_index(region); 263 } 264 }; 265 266 HumongousReclaimCandidates _humongous_reclaim_candidates; 267 // Stores whether during humongous object registration we found candidate regions. 268 // If not, we can skip a few steps. 269 bool _has_humongous_reclaim_candidates; 270 271 volatile uint _gc_time_stamp; 272 273 G1HRPrinter _hr_printer; 274 275 // It decides whether an explicit GC should start a concurrent cycle 276 // instead of doing a STW GC. Currently, a concurrent cycle is 277 // explicitly started if: 278 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 279 // (b) cause == _g1_humongous_allocation 280 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 281 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 282 // (e) cause == _wb_conc_mark 283 bool should_do_concurrent_full_gc(GCCause::Cause cause); 284 285 // indicates whether we are in young or mixed GC mode 286 G1CollectorState _collector_state; 287 288 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 289 // concurrent cycles) we have started. 290 volatile uint _old_marking_cycles_started; 291 292 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 293 // concurrent cycles) we have completed. 294 volatile uint _old_marking_cycles_completed; 295 296 // This is a non-product method that is helpful for testing. It is 297 // called at the end of a GC and artificially expands the heap by 298 // allocating a number of dead regions. This way we can induce very 299 // frequent marking cycles and stress the cleanup / concurrent 300 // cleanup code more (as all the regions that will be allocated by 301 // this method will be found dead by the marking cycle). 302 void allocate_dummy_regions() PRODUCT_RETURN; 303 304 // Clear RSets after a compaction. It also resets the GC time stamps. 305 void clear_rsets_post_compaction(); 306 307 // If the HR printer is active, dump the state of the regions in the 308 // heap after a compaction. 309 void print_hrm_post_compaction(); 310 311 // Create a memory mapper for auxiliary data structures of the given size and 312 // translation factor. 313 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 314 size_t size, 315 size_t translation_factor); 316 317 static G1Policy* create_g1_policy(STWGCTimer* gc_timer); 318 319 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 320 321 // These are macros so that, if the assert fires, we get the correct 322 // line number, file, etc. 323 324 #define heap_locking_asserts_params(_extra_message_) \ 325 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 326 (_extra_message_), \ 327 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 328 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 329 BOOL_TO_STR(Thread::current()->is_VM_thread()) 330 331 #define assert_heap_locked() \ 332 do { \ 333 assert(Heap_lock->owned_by_self(), \ 334 heap_locking_asserts_params("should be holding the Heap_lock")); \ 335 } while (0) 336 337 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 338 do { \ 339 assert(Heap_lock->owned_by_self() || \ 340 (SafepointSynchronize::is_at_safepoint() && \ 341 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 342 heap_locking_asserts_params("should be holding the Heap_lock or " \ 343 "should be at a safepoint")); \ 344 } while (0) 345 346 #define assert_heap_locked_and_not_at_safepoint() \ 347 do { \ 348 assert(Heap_lock->owned_by_self() && \ 349 !SafepointSynchronize::is_at_safepoint(), \ 350 heap_locking_asserts_params("should be holding the Heap_lock and " \ 351 "should not be at a safepoint")); \ 352 } while (0) 353 354 #define assert_heap_not_locked() \ 355 do { \ 356 assert(!Heap_lock->owned_by_self(), \ 357 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 358 } while (0) 359 360 #define assert_heap_not_locked_and_not_at_safepoint() \ 361 do { \ 362 assert(!Heap_lock->owned_by_self() && \ 363 !SafepointSynchronize::is_at_safepoint(), \ 364 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 365 "should not be at a safepoint")); \ 366 } while (0) 367 368 #define assert_at_safepoint(_should_be_vm_thread_) \ 369 do { \ 370 assert(SafepointSynchronize::is_at_safepoint() && \ 371 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 372 heap_locking_asserts_params("should be at a safepoint")); \ 373 } while (0) 374 375 #define assert_not_at_safepoint() \ 376 do { \ 377 assert(!SafepointSynchronize::is_at_safepoint(), \ 378 heap_locking_asserts_params("should not be at a safepoint")); \ 379 } while (0) 380 381 protected: 382 383 // The young region list. 384 G1EdenRegions _eden; 385 G1SurvivorRegions _survivor; 386 387 STWGCTimer* _gc_timer_stw; 388 389 G1NewTracer* _gc_tracer_stw; 390 391 // The current policy object for the collector. 392 G1Policy* _g1_policy; 393 G1HeapSizingPolicy* _heap_sizing_policy; 394 395 G1CollectionSet _collection_set; 396 397 // This is the second level of trying to allocate a new region. If 398 // new_region() didn't find a region on the free_list, this call will 399 // check whether there's anything available on the 400 // secondary_free_list and/or wait for more regions to appear on 401 // that list, if _free_regions_coming is set. 402 HeapRegion* new_region_try_secondary_free_list(bool is_old); 403 404 // Try to allocate a single non-humongous HeapRegion sufficient for 405 // an allocation of the given word_size. If do_expand is true, 406 // attempt to expand the heap if necessary to satisfy the allocation 407 // request. If the region is to be used as an old region or for a 408 // humongous object, set is_old to true. If not, to false. 409 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 410 411 // Initialize a contiguous set of free regions of length num_regions 412 // and starting at index first so that they appear as a single 413 // humongous region. 414 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 415 uint num_regions, 416 size_t word_size, 417 AllocationContext_t context); 418 419 // Attempt to allocate a humongous object of the given size. Return 420 // NULL if unsuccessful. 421 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 422 423 // The following two methods, allocate_new_tlab() and 424 // mem_allocate(), are the two main entry points from the runtime 425 // into the G1's allocation routines. They have the following 426 // assumptions: 427 // 428 // * They should both be called outside safepoints. 429 // 430 // * They should both be called without holding the Heap_lock. 431 // 432 // * All allocation requests for new TLABs should go to 433 // allocate_new_tlab(). 434 // 435 // * All non-TLAB allocation requests should go to mem_allocate(). 436 // 437 // * If either call cannot satisfy the allocation request using the 438 // current allocating region, they will try to get a new one. If 439 // this fails, they will attempt to do an evacuation pause and 440 // retry the allocation. 441 // 442 // * If all allocation attempts fail, even after trying to schedule 443 // an evacuation pause, allocate_new_tlab() will return NULL, 444 // whereas mem_allocate() will attempt a heap expansion and/or 445 // schedule a Full GC. 446 // 447 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 448 // should never be called with word_size being humongous. All 449 // humongous allocation requests should go to mem_allocate() which 450 // will satisfy them with a special path. 451 452 virtual HeapWord* allocate_new_tlab(size_t word_size); 453 454 virtual HeapWord* mem_allocate(size_t word_size, 455 bool* gc_overhead_limit_was_exceeded); 456 457 // First-level mutator allocation attempt: try to allocate out of 458 // the mutator alloc region without taking the Heap_lock. This 459 // should only be used for non-humongous allocations. 460 inline HeapWord* attempt_allocation(size_t word_size); 461 462 // Second-level mutator allocation attempt: take the Heap_lock and 463 // retry the allocation attempt, potentially scheduling a GC 464 // pause. This should only be used for non-humongous allocations. 465 HeapWord* attempt_allocation_slow(size_t word_size, 466 AllocationContext_t context); 467 468 // Takes the Heap_lock and attempts a humongous allocation. It can 469 // potentially schedule a GC pause. 470 HeapWord* attempt_allocation_humongous(size_t word_size); 471 472 // Allocation attempt that should be called during safepoints (e.g., 473 // at the end of a successful GC). expect_null_mutator_alloc_region 474 // specifies whether the mutator alloc region is expected to be NULL 475 // or not. 476 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 477 AllocationContext_t context, 478 bool expect_null_mutator_alloc_region); 479 480 // These methods are the "callbacks" from the G1AllocRegion class. 481 482 // For mutator alloc regions. 483 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 484 void retire_mutator_alloc_region(HeapRegion* alloc_region, 485 size_t allocated_bytes); 486 487 // For GC alloc regions. 488 bool has_more_regions(InCSetState dest); 489 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 490 void retire_gc_alloc_region(HeapRegion* alloc_region, 491 size_t allocated_bytes, InCSetState dest); 492 493 // - if explicit_gc is true, the GC is for a System.gc() etc, 494 // otherwise it's for a failed allocation. 495 // - if clear_all_soft_refs is true, all soft references should be 496 // cleared during the GC. 497 // - it returns false if it is unable to do the collection due to the 498 // GC locker being active, true otherwise. 499 bool do_full_collection(bool explicit_gc, 500 bool clear_all_soft_refs); 501 502 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 503 virtual void do_full_collection(bool clear_all_soft_refs); 504 505 // Resize the heap if necessary after a full collection. 506 void resize_if_necessary_after_full_collection(); 507 508 // Callback from VM_G1CollectForAllocation operation. 509 // This function does everything necessary/possible to satisfy a 510 // failed allocation request (including collection, expansion, etc.) 511 HeapWord* satisfy_failed_allocation(size_t word_size, 512 AllocationContext_t context, 513 bool* succeeded); 514 private: 515 // Internal helpers used during full GC to split it up to 516 // increase readability. 517 void abort_concurrent_cycle(); 518 void verify_before_full_collection(bool explicit_gc); 519 void prepare_heap_for_full_collection(); 520 void prepare_heap_for_mutators(); 521 void abort_refinement(); 522 void verify_after_full_collection(); 523 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 524 525 // Helper method for satisfy_failed_allocation() 526 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 527 AllocationContext_t context, 528 bool do_gc, 529 bool clear_all_soft_refs, 530 bool expect_null_mutator_alloc_region, 531 bool* gc_succeeded); 532 533 protected: 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, AllocationContext_t context); 539 540 // Preserve any referents discovered by concurrent marking that have not yet been 541 // copied by the STW pause. 542 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 543 // Process any reference objects discovered during 544 // an incremental evacuation pause. 545 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 546 547 // Enqueue any remaining discovered references 548 // after processing. 549 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 550 551 // Merges the information gathered on a per-thread basis for all worker threads 552 // during GC into global variables. 553 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 554 public: 555 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 556 557 WorkGang* workers() const { return _workers; } 558 559 G1Allocator* allocator() { 560 return _allocator; 561 } 562 563 G1HeapVerifier* verifier() { 564 return _verifier; 565 } 566 567 G1MonitoringSupport* g1mm() { 568 assert(_g1mm != NULL, "should have been initialized"); 569 return _g1mm; 570 } 571 572 // Expand the garbage-first heap by at least the given size (in bytes!). 573 // Returns true if the heap was expanded by the requested amount; 574 // false otherwise. 575 // (Rounds up to a HeapRegion boundary.) 576 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 577 578 // Returns the PLAB statistics for a given destination. 579 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 580 581 // Determines PLAB size for a given destination. 582 inline size_t desired_plab_sz(InCSetState dest); 583 584 // Do anything common to GC's. 585 void gc_prologue(bool full); 586 void gc_epilogue(bool full); 587 588 // Modify the reclaim candidate set and test for presence. 589 // These are only valid for starts_humongous regions. 590 inline void set_humongous_reclaim_candidate(uint region, bool value); 591 inline bool is_humongous_reclaim_candidate(uint region); 592 593 // Remove from the reclaim candidate set. Also remove from the 594 // collection set so that later encounters avoid the slow path. 595 inline void set_humongous_is_live(oop obj); 596 597 // Register the given region to be part of the collection set. 598 inline void register_humongous_region_with_cset(uint index); 599 // Register regions with humongous objects (actually on the start region) in 600 // the in_cset_fast_test table. 601 void register_humongous_regions_with_cset(); 602 // We register a region with the fast "in collection set" test. We 603 // simply set to true the array slot corresponding to this region. 604 void register_young_region_with_cset(HeapRegion* r) { 605 _in_cset_fast_test.set_in_young(r->hrm_index()); 606 } 607 void register_old_region_with_cset(HeapRegion* r) { 608 _in_cset_fast_test.set_in_old(r->hrm_index()); 609 } 610 inline void register_ext_region_with_cset(HeapRegion* r) { 611 _in_cset_fast_test.set_ext(r->hrm_index()); 612 } 613 void clear_in_cset(const HeapRegion* hr) { 614 _in_cset_fast_test.clear(hr); 615 } 616 617 void clear_cset_fast_test() { 618 _in_cset_fast_test.clear(); 619 } 620 621 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 622 623 // This is called at the start of either a concurrent cycle or a Full 624 // GC to update the number of old marking cycles started. 625 void increment_old_marking_cycles_started(); 626 627 // This is called at the end of either a concurrent cycle or a Full 628 // GC to update the number of old marking cycles completed. Those two 629 // can happen in a nested fashion, i.e., we start a concurrent 630 // cycle, a Full GC happens half-way through it which ends first, 631 // and then the cycle notices that a Full GC happened and ends 632 // too. The concurrent parameter is a boolean to help us do a bit 633 // tighter consistency checking in the method. If concurrent is 634 // false, the caller is the inner caller in the nesting (i.e., the 635 // Full GC). If concurrent is true, the caller is the outer caller 636 // in this nesting (i.e., the concurrent cycle). Further nesting is 637 // not currently supported. The end of this call also notifies 638 // the FullGCCount_lock in case a Java thread is waiting for a full 639 // GC to happen (e.g., it called System.gc() with 640 // +ExplicitGCInvokesConcurrent). 641 void increment_old_marking_cycles_completed(bool concurrent); 642 643 uint old_marking_cycles_completed() { 644 return _old_marking_cycles_completed; 645 } 646 647 G1HRPrinter* hr_printer() { return &_hr_printer; } 648 649 // Allocates a new heap region instance. 650 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 651 652 // Allocate the highest free region in the reserved heap. This will commit 653 // regions as necessary. 654 HeapRegion* alloc_highest_free_region(); 655 656 // Frees a non-humongous region by initializing its contents and 657 // adding it to the free list that's passed as a parameter (this is 658 // usually a local list which will be appended to the master free 659 // list later). The used bytes of freed regions are accumulated in 660 // pre_used. If skip_remset is true, the region's RSet will not be freed 661 // up. If skip_hot_card_cache is true, the region's hot card cache will not 662 // be freed up. The assumption is that this will be done later. 663 // The locked parameter indicates if the caller has already taken 664 // care of proper synchronization. This may allow some optimizations. 665 void free_region(HeapRegion* hr, 666 FreeRegionList* free_list, 667 bool skip_remset, 668 bool skip_hot_card_cache = false, 669 bool locked = false); 670 671 // It dirties the cards that cover the block so that the post 672 // write barrier never queues anything when updating objects on this 673 // block. It is assumed (and in fact we assert) that the block 674 // belongs to a young region. 675 inline void dirty_young_block(HeapWord* start, size_t word_size); 676 677 // Frees a humongous region by collapsing it into individual regions 678 // and calling free_region() for each of them. The freed regions 679 // will be added to the free list that's passed as a parameter (this 680 // is usually a local list which will be appended to the master free 681 // list later). The used bytes of freed regions are accumulated in 682 // pre_used. If skip_remset is true, the region's RSet will not be freed 683 // up. The assumption is that this will be done later. 684 void free_humongous_region(HeapRegion* hr, 685 FreeRegionList* free_list, 686 bool skip_remset); 687 688 // Facility for allocating in 'archive' regions in high heap memory and 689 // recording the allocated ranges. These should all be called from the 690 // VM thread at safepoints, without the heap lock held. They can be used 691 // to create and archive a set of heap regions which can be mapped at the 692 // same fixed addresses in a subsequent JVM invocation. 693 void begin_archive_alloc_range(bool open = false); 694 695 // Check if the requested size would be too large for an archive allocation. 696 bool is_archive_alloc_too_large(size_t word_size); 697 698 // Allocate memory of the requested size from the archive region. This will 699 // return NULL if the size is too large or if no memory is available. It 700 // does not trigger a garbage collection. 701 HeapWord* archive_mem_allocate(size_t word_size); 702 703 // Optionally aligns the end address and returns the allocated ranges in 704 // an array of MemRegions in order of ascending addresses. 705 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 706 size_t end_alignment_in_bytes = 0); 707 708 // Facility for allocating a fixed range within the heap and marking 709 // the containing regions as 'archive'. For use at JVM init time, when the 710 // caller may mmap archived heap data at the specified range(s). 711 // Verify that the MemRegions specified in the argument array are within the 712 // reserved heap. 713 bool check_archive_addresses(MemRegion* range, size_t count); 714 715 // Commit the appropriate G1 regions containing the specified MemRegions 716 // and mark them as 'archive' regions. The regions in the array must be 717 // non-overlapping and in order of ascending address. 718 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 719 720 // Insert any required filler objects in the G1 regions around the specified 721 // ranges to make the regions parseable. This must be called after 722 // alloc_archive_regions, and after class loading has occurred. 723 void fill_archive_regions(MemRegion* range, size_t count); 724 725 // For each of the specified MemRegions, uncommit the containing G1 regions 726 // which had been allocated by alloc_archive_regions. This should be called 727 // rather than fill_archive_regions at JVM init time if the archive file 728 // mapping failed, with the same non-overlapping and sorted MemRegion array. 729 void dealloc_archive_regions(MemRegion* range, size_t count); 730 731 protected: 732 733 // Shrink the garbage-first heap by at most the given size (in bytes!). 734 // (Rounds down to a HeapRegion boundary.) 735 virtual void shrink(size_t expand_bytes); 736 void shrink_helper(size_t expand_bytes); 737 738 #if TASKQUEUE_STATS 739 static void print_taskqueue_stats_hdr(outputStream* const st); 740 void print_taskqueue_stats() const; 741 void reset_taskqueue_stats(); 742 #endif // TASKQUEUE_STATS 743 744 // Schedule the VM operation that will do an evacuation pause to 745 // satisfy an allocation request of word_size. *succeeded will 746 // return whether the VM operation was successful (it did do an 747 // evacuation pause) or not (another thread beat us to it or the GC 748 // locker was active). Given that we should not be holding the 749 // Heap_lock when we enter this method, we will pass the 750 // gc_count_before (i.e., total_collections()) as a parameter since 751 // it has to be read while holding the Heap_lock. Currently, both 752 // methods that call do_collection_pause() release the Heap_lock 753 // before the call, so it's easy to read gc_count_before just before. 754 HeapWord* do_collection_pause(size_t word_size, 755 uint gc_count_before, 756 bool* succeeded, 757 GCCause::Cause gc_cause); 758 759 void wait_for_root_region_scanning(); 760 761 // The guts of the incremental collection pause, executed by the vm 762 // thread. It returns false if it is unable to do the collection due 763 // to the GC locker being active, true otherwise 764 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 765 766 // Actually do the work of evacuating the collection set. 767 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 768 769 void pre_evacuate_collection_set(); 770 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 771 772 // Print the header for the per-thread termination statistics. 773 static void print_termination_stats_hdr(); 774 // Print actual per-thread termination statistics. 775 void print_termination_stats(uint worker_id, 776 double elapsed_ms, 777 double strong_roots_ms, 778 double term_ms, 779 size_t term_attempts, 780 size_t alloc_buffer_waste, 781 size_t undo_waste) const; 782 // Update object copying statistics. 783 void record_obj_copy_mem_stats(); 784 785 // The hot card cache for remembered set insertion optimization. 786 G1HotCardCache* _hot_card_cache; 787 788 // The g1 remembered set of the heap. 789 G1RemSet* _g1_rem_set; 790 791 // A set of cards that cover the objects for which the Rsets should be updated 792 // concurrently after the collection. 793 DirtyCardQueueSet _dirty_card_queue_set; 794 795 // After a collection pause, convert the regions in the collection set into free 796 // regions. 797 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 798 799 // Abandon the current collection set without recording policy 800 // statistics or updating free lists. 801 void abandon_collection_set(G1CollectionSet* collection_set); 802 803 // The concurrent marker (and the thread it runs in.) 804 G1ConcurrentMark* _cm; 805 ConcurrentMarkThread* _cmThread; 806 807 // The concurrent refiner. 808 G1ConcurrentRefine* _cr; 809 810 // The parallel task queues 811 RefToScanQueueSet *_task_queues; 812 813 // True iff a evacuation has failed in the current collection. 814 bool _evacuation_failed; 815 816 EvacuationFailedInfo* _evacuation_failed_info_array; 817 818 // Failed evacuations cause some logical from-space objects to have 819 // forwarding pointers to themselves. Reset them. 820 void remove_self_forwarding_pointers(); 821 822 // Restore the objects in the regions in the collection set after an 823 // evacuation failure. 824 void restore_after_evac_failure(); 825 826 PreservedMarksSet _preserved_marks_set; 827 828 // Preserve the mark of "obj", if necessary, in preparation for its mark 829 // word being overwritten with a self-forwarding-pointer. 830 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 831 832 #ifndef PRODUCT 833 // Support for forcing evacuation failures. Analogous to 834 // PromotionFailureALot for the other collectors. 835 836 // Records whether G1EvacuationFailureALot should be in effect 837 // for the current GC 838 bool _evacuation_failure_alot_for_current_gc; 839 840 // Used to record the GC number for interval checking when 841 // determining whether G1EvaucationFailureALot is in effect 842 // for the current GC. 843 size_t _evacuation_failure_alot_gc_number; 844 845 // Count of the number of evacuations between failures. 846 volatile size_t _evacuation_failure_alot_count; 847 848 // Set whether G1EvacuationFailureALot should be in effect 849 // for the current GC (based upon the type of GC and which 850 // command line flags are set); 851 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 852 bool during_initial_mark, 853 bool during_marking); 854 855 inline void set_evacuation_failure_alot_for_current_gc(); 856 857 // Return true if it's time to cause an evacuation failure. 858 inline bool evacuation_should_fail(); 859 860 // Reset the G1EvacuationFailureALot counters. Should be called at 861 // the end of an evacuation pause in which an evacuation failure occurred. 862 inline void reset_evacuation_should_fail(); 863 #endif // !PRODUCT 864 865 // ("Weak") Reference processing support. 866 // 867 // G1 has 2 instances of the reference processor class. One 868 // (_ref_processor_cm) handles reference object discovery 869 // and subsequent processing during concurrent marking cycles. 870 // 871 // The other (_ref_processor_stw) handles reference object 872 // discovery and processing during full GCs and incremental 873 // evacuation pauses. 874 // 875 // During an incremental pause, reference discovery will be 876 // temporarily disabled for _ref_processor_cm and will be 877 // enabled for _ref_processor_stw. At the end of the evacuation 878 // pause references discovered by _ref_processor_stw will be 879 // processed and discovery will be disabled. The previous 880 // setting for reference object discovery for _ref_processor_cm 881 // will be re-instated. 882 // 883 // At the start of marking: 884 // * Discovery by the CM ref processor is verified to be inactive 885 // and it's discovered lists are empty. 886 // * Discovery by the CM ref processor is then enabled. 887 // 888 // At the end of marking: 889 // * Any references on the CM ref processor's discovered 890 // lists are processed (possibly MT). 891 // 892 // At the start of full GC we: 893 // * Disable discovery by the CM ref processor and 894 // empty CM ref processor's discovered lists 895 // (without processing any entries). 896 // * Verify that the STW ref processor is inactive and it's 897 // discovered lists are empty. 898 // * Temporarily set STW ref processor discovery as single threaded. 899 // * Temporarily clear the STW ref processor's _is_alive_non_header 900 // field. 901 // * Finally enable discovery by the STW ref processor. 902 // 903 // The STW ref processor is used to record any discovered 904 // references during the full GC. 905 // 906 // At the end of a full GC we: 907 // * Enqueue any reference objects discovered by the STW ref processor 908 // that have non-live referents. This has the side-effect of 909 // making the STW ref processor inactive by disabling discovery. 910 // * Verify that the CM ref processor is still inactive 911 // and no references have been placed on it's discovered 912 // lists (also checked as a precondition during initial marking). 913 914 // The (stw) reference processor... 915 ReferenceProcessor* _ref_processor_stw; 916 917 // During reference object discovery, the _is_alive_non_header 918 // closure (if non-null) is applied to the referent object to 919 // determine whether the referent is live. If so then the 920 // reference object does not need to be 'discovered' and can 921 // be treated as a regular oop. This has the benefit of reducing 922 // the number of 'discovered' reference objects that need to 923 // be processed. 924 // 925 // Instance of the is_alive closure for embedding into the 926 // STW reference processor as the _is_alive_non_header field. 927 // Supplying a value for the _is_alive_non_header field is 928 // optional but doing so prevents unnecessary additions to 929 // the discovered lists during reference discovery. 930 G1STWIsAliveClosure _is_alive_closure_stw; 931 932 // The (concurrent marking) reference processor... 933 ReferenceProcessor* _ref_processor_cm; 934 935 // Instance of the concurrent mark is_alive closure for embedding 936 // into the Concurrent Marking reference processor as the 937 // _is_alive_non_header field. Supplying a value for the 938 // _is_alive_non_header field is optional but doing so prevents 939 // unnecessary additions to the discovered lists during reference 940 // discovery. 941 G1CMIsAliveClosure _is_alive_closure_cm; 942 943 volatile bool _free_regions_coming; 944 945 public: 946 947 RefToScanQueue *task_queue(uint i) const; 948 949 uint num_task_queues() const; 950 951 // A set of cards where updates happened during the GC 952 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 953 954 // Create a G1CollectedHeap with the specified policy. 955 // Must call the initialize method afterwards. 956 // May not return if something goes wrong. 957 G1CollectedHeap(G1CollectorPolicy* policy); 958 959 private: 960 jint initialize_concurrent_refinement(); 961 jint initialize_young_gen_sampling_thread(); 962 public: 963 // Initialize the G1CollectedHeap to have the initial and 964 // maximum sizes and remembered and barrier sets 965 // specified by the policy object. 966 jint initialize(); 967 968 virtual void stop(); 969 virtual void safepoint_synchronize_begin(); 970 virtual void safepoint_synchronize_end(); 971 972 // Return the (conservative) maximum heap alignment for any G1 heap 973 static size_t conservative_max_heap_alignment(); 974 975 // Does operations required after initialization has been done. 976 void post_initialize(); 977 978 // Initialize weak reference processing. 979 void ref_processing_init(); 980 981 virtual Name kind() const { 982 return CollectedHeap::G1CollectedHeap; 983 } 984 985 virtual const char* name() const { 986 return "G1"; 987 } 988 989 const G1CollectorState* collector_state() const { return &_collector_state; } 990 G1CollectorState* collector_state() { return &_collector_state; } 991 992 // The current policy object for the collector. 993 G1Policy* g1_policy() const { return _g1_policy; } 994 995 const G1CollectionSet* collection_set() const { return &_collection_set; } 996 G1CollectionSet* collection_set() { return &_collection_set; } 997 998 virtual CollectorPolicy* collector_policy() const; 999 1000 virtual SoftRefPolicy* soft_ref_policy(); 1001 1002 virtual GrowableArray<GCMemoryManager*> memory_managers(); 1003 virtual GrowableArray<MemoryPool*> memory_pools(); 1004 1005 // The rem set and barrier set. 1006 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1007 1008 // Try to minimize the remembered set. 1009 void scrub_rem_set(); 1010 1011 uint get_gc_time_stamp() { 1012 return _gc_time_stamp; 1013 } 1014 1015 inline void reset_gc_time_stamp(); 1016 1017 void check_gc_time_stamps() PRODUCT_RETURN; 1018 1019 inline void increment_gc_time_stamp(); 1020 1021 // Reset the given region's GC timestamp. If it's starts humongous, 1022 // also reset the GC timestamp of its corresponding 1023 // continues humongous regions too. 1024 void reset_gc_time_stamps(HeapRegion* hr); 1025 1026 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1027 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1028 1029 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1030 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1031 1032 // The shared block offset table array. 1033 G1BlockOffsetTable* bot() const { return _bot; } 1034 1035 // Reference Processing accessors 1036 1037 // The STW reference processor.... 1038 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1039 1040 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1041 1042 // The Concurrent Marking reference processor... 1043 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1044 1045 size_t unused_committed_regions_in_bytes() const; 1046 virtual size_t capacity() const; 1047 virtual size_t used() const; 1048 // This should be called when we're not holding the heap lock. The 1049 // result might be a bit inaccurate. 1050 size_t used_unlocked() const; 1051 size_t recalculate_used() const; 1052 1053 // These virtual functions do the actual allocation. 1054 // Some heaps may offer a contiguous region for shared non-blocking 1055 // allocation, via inlined code (by exporting the address of the top and 1056 // end fields defining the extent of the contiguous allocation region.) 1057 // But G1CollectedHeap doesn't yet support this. 1058 1059 virtual bool is_maximal_no_gc() const { 1060 return _hrm.available() == 0; 1061 } 1062 1063 // Returns whether there are any regions left in the heap for allocation. 1064 bool has_regions_left_for_allocation() const { 1065 return !is_maximal_no_gc() || num_free_regions() != 0; 1066 } 1067 1068 // The current number of regions in the heap. 1069 uint num_regions() const { return _hrm.length(); } 1070 1071 // The max number of regions in the heap. 1072 uint max_regions() const { return _hrm.max_length(); } 1073 1074 // The number of regions that are completely free. 1075 uint num_free_regions() const { return _hrm.num_free_regions(); } 1076 1077 MemoryUsage get_auxiliary_data_memory_usage() const { 1078 return _hrm.get_auxiliary_data_memory_usage(); 1079 } 1080 1081 // The number of regions that are not completely free. 1082 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1083 1084 #ifdef ASSERT 1085 bool is_on_master_free_list(HeapRegion* hr) { 1086 return _hrm.is_free(hr); 1087 } 1088 #endif // ASSERT 1089 1090 // Wrapper for the region list operations that can be called from 1091 // methods outside this class. 1092 1093 void secondary_free_list_add(FreeRegionList* list) { 1094 _secondary_free_list.add_ordered(list); 1095 } 1096 1097 void append_secondary_free_list() { 1098 _hrm.insert_list_into_free_list(&_secondary_free_list); 1099 } 1100 1101 void append_secondary_free_list_if_not_empty_with_lock() { 1102 // If the secondary free list looks empty there's no reason to 1103 // take the lock and then try to append it. 1104 if (!_secondary_free_list.is_empty()) { 1105 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1106 append_secondary_free_list(); 1107 } 1108 } 1109 1110 inline void old_set_add(HeapRegion* hr); 1111 inline void old_set_remove(HeapRegion* hr); 1112 1113 size_t non_young_capacity_bytes() { 1114 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1115 } 1116 1117 void set_free_regions_coming(); 1118 void reset_free_regions_coming(); 1119 bool free_regions_coming() { return _free_regions_coming; } 1120 void wait_while_free_regions_coming(); 1121 1122 // Determine whether the given region is one that we are using as an 1123 // old GC alloc region. 1124 bool is_old_gc_alloc_region(HeapRegion* hr); 1125 1126 // Perform a collection of the heap; intended for use in implementing 1127 // "System.gc". This probably implies as full a collection as the 1128 // "CollectedHeap" supports. 1129 virtual void collect(GCCause::Cause cause); 1130 1131 // True iff an evacuation has failed in the most-recent collection. 1132 bool evacuation_failed() { return _evacuation_failed; } 1133 1134 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1135 void prepend_to_freelist(FreeRegionList* list); 1136 void decrement_summary_bytes(size_t bytes); 1137 1138 virtual bool is_in(const void* p) const; 1139 #ifdef ASSERT 1140 // Returns whether p is in one of the available areas of the heap. Slow but 1141 // extensive version. 1142 bool is_in_exact(const void* p) const; 1143 #endif 1144 1145 // Return "TRUE" iff the given object address is within the collection 1146 // set. Assumes that the reference points into the heap. 1147 inline bool is_in_cset(const HeapRegion *hr); 1148 inline bool is_in_cset(oop obj); 1149 inline bool is_in_cset(HeapWord* addr); 1150 1151 inline bool is_in_cset_or_humongous(const oop obj); 1152 1153 private: 1154 // This array is used for a quick test on whether a reference points into 1155 // the collection set or not. Each of the array's elements denotes whether the 1156 // corresponding region is in the collection set or not. 1157 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1158 1159 public: 1160 1161 inline InCSetState in_cset_state(const oop obj); 1162 1163 // Return "TRUE" iff the given object address is in the reserved 1164 // region of g1. 1165 bool is_in_g1_reserved(const void* p) const { 1166 return _hrm.reserved().contains(p); 1167 } 1168 1169 // Returns a MemRegion that corresponds to the space that has been 1170 // reserved for the heap 1171 MemRegion g1_reserved() const { 1172 return _hrm.reserved(); 1173 } 1174 1175 virtual bool is_in_closed_subset(const void* p) const; 1176 1177 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1178 1179 G1CardTable* card_table() const { 1180 return _card_table; 1181 } 1182 1183 // Iteration functions. 1184 1185 // Iterate over all objects, calling "cl.do_object" on each. 1186 virtual void object_iterate(ObjectClosure* cl); 1187 1188 virtual void safe_object_iterate(ObjectClosure* cl) { 1189 object_iterate(cl); 1190 } 1191 1192 // Iterate over heap regions, in address order, terminating the 1193 // iteration early if the "do_heap_region" method returns "true". 1194 void heap_region_iterate(HeapRegionClosure* blk) const; 1195 1196 // Return the region with the given index. It assumes the index is valid. 1197 inline HeapRegion* region_at(uint index) const; 1198 1199 // Return the next region (by index) that is part of the same 1200 // humongous object that hr is part of. 1201 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1202 1203 // Calculate the region index of the given address. Given address must be 1204 // within the heap. 1205 inline uint addr_to_region(HeapWord* addr) const; 1206 1207 inline HeapWord* bottom_addr_for_region(uint index) const; 1208 1209 // Two functions to iterate over the heap regions in parallel. Threads 1210 // compete using the HeapRegionClaimer to claim the regions before 1211 // applying the closure on them. 1212 // The _from_worker_offset version uses the HeapRegionClaimer and 1213 // the worker id to calculate a start offset to prevent all workers to 1214 // start from the point. 1215 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1216 HeapRegionClaimer* hrclaimer, 1217 uint worker_id) const; 1218 1219 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1220 HeapRegionClaimer* hrclaimer) const; 1221 1222 // Iterate over the regions (if any) in the current collection set. 1223 void collection_set_iterate(HeapRegionClosure* blk); 1224 1225 // Iterate over the regions (if any) in the current collection set. Starts the 1226 // iteration over the entire collection set so that the start regions of a given 1227 // worker id over the set active_workers are evenly spread across the set of 1228 // collection set regions. 1229 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1230 1231 // Returns the HeapRegion that contains addr. addr must not be NULL. 1232 template <class T> 1233 inline HeapRegion* heap_region_containing(const T addr) const; 1234 1235 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1236 // each address in the (reserved) heap is a member of exactly 1237 // one block. The defining characteristic of a block is that it is 1238 // possible to find its size, and thus to progress forward to the next 1239 // block. (Blocks may be of different sizes.) Thus, blocks may 1240 // represent Java objects, or they might be free blocks in a 1241 // free-list-based heap (or subheap), as long as the two kinds are 1242 // distinguishable and the size of each is determinable. 1243 1244 // Returns the address of the start of the "block" that contains the 1245 // address "addr". We say "blocks" instead of "object" since some heaps 1246 // may not pack objects densely; a chunk may either be an object or a 1247 // non-object. 1248 virtual HeapWord* block_start(const void* addr) const; 1249 1250 // Requires "addr" to be the start of a chunk, and returns its size. 1251 // "addr + size" is required to be the start of a new chunk, or the end 1252 // of the active area of the heap. 1253 virtual size_t block_size(const HeapWord* addr) const; 1254 1255 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1256 // the block is an object. 1257 virtual bool block_is_obj(const HeapWord* addr) const; 1258 1259 // Section on thread-local allocation buffers (TLABs) 1260 // See CollectedHeap for semantics. 1261 1262 bool supports_tlab_allocation() const; 1263 size_t tlab_capacity(Thread* ignored) const; 1264 size_t tlab_used(Thread* ignored) const; 1265 size_t max_tlab_size() const; 1266 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1267 1268 inline bool is_in_young(const oop obj); 1269 1270 // Returns "true" iff the given word_size is "very large". 1271 static bool is_humongous(size_t word_size) { 1272 // Note this has to be strictly greater-than as the TLABs 1273 // are capped at the humongous threshold and we want to 1274 // ensure that we don't try to allocate a TLAB as 1275 // humongous and that we don't allocate a humongous 1276 // object in a TLAB. 1277 return word_size > _humongous_object_threshold_in_words; 1278 } 1279 1280 // Returns the humongous threshold for a specific region size 1281 static size_t humongous_threshold_for(size_t region_size) { 1282 return (region_size / 2); 1283 } 1284 1285 // Returns the number of regions the humongous object of the given word size 1286 // requires. 1287 static size_t humongous_obj_size_in_regions(size_t word_size); 1288 1289 // Print the maximum heap capacity. 1290 virtual size_t max_capacity() const; 1291 1292 virtual jlong millis_since_last_gc(); 1293 1294 1295 // Convenience function to be used in situations where the heap type can be 1296 // asserted to be this type. 1297 static G1CollectedHeap* heap(); 1298 1299 void set_region_short_lived_locked(HeapRegion* hr); 1300 // add appropriate methods for any other surv rate groups 1301 1302 const G1SurvivorRegions* survivor() const { return &_survivor; } 1303 1304 uint survivor_regions_count() const { 1305 return _survivor.length(); 1306 } 1307 1308 uint eden_regions_count() const { 1309 return _eden.length(); 1310 } 1311 1312 uint young_regions_count() const { 1313 return _eden.length() + _survivor.length(); 1314 } 1315 1316 uint old_regions_count() const { return _old_set.length(); } 1317 1318 uint humongous_regions_count() const { return _humongous_set.length(); } 1319 1320 #ifdef ASSERT 1321 bool check_young_list_empty(); 1322 #endif 1323 1324 // *** Stuff related to concurrent marking. It's not clear to me that so 1325 // many of these need to be public. 1326 1327 // The functions below are helper functions that a subclass of 1328 // "CollectedHeap" can use in the implementation of its virtual 1329 // functions. 1330 // This performs a concurrent marking of the live objects in a 1331 // bitmap off to the side. 1332 void doConcurrentMark(); 1333 1334 bool isMarkedNext(oop obj) const; 1335 1336 // Determine if an object is dead, given the object and also 1337 // the region to which the object belongs. An object is dead 1338 // iff a) it was not allocated since the last mark, b) it 1339 // is not marked, and c) it is not in an archive region. 1340 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1341 return 1342 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1343 !hr->is_archive(); 1344 } 1345 1346 // This function returns true when an object has been 1347 // around since the previous marking and hasn't yet 1348 // been marked during this marking, and is not in an archive region. 1349 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1350 return 1351 !hr->obj_allocated_since_next_marking(obj) && 1352 !isMarkedNext(obj) && 1353 !hr->is_archive(); 1354 } 1355 1356 // Determine if an object is dead, given only the object itself. 1357 // This will find the region to which the object belongs and 1358 // then call the region version of the same function. 1359 1360 // Added if it is NULL it isn't dead. 1361 1362 inline bool is_obj_dead(const oop obj) const; 1363 1364 inline bool is_obj_ill(const oop obj) const; 1365 1366 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1367 inline bool is_obj_dead_full(const oop obj) const; 1368 1369 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1370 1371 // Refinement 1372 1373 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1374 1375 // Optimized nmethod scanning support routines 1376 1377 // Is an oop scavengeable 1378 virtual bool is_scavengable(oop obj); 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 // Free up superfluous code root memory. 1387 void purge_code_root_memory(); 1388 1389 // Rebuild the strong code root lists for each region 1390 // after a full GC. 1391 void rebuild_strong_code_roots(); 1392 1393 // Partial cleaning used when class unloading is disabled. 1394 // Let the caller choose what structures to clean out: 1395 // - StringTable 1396 // - SymbolTable 1397 // - StringDeduplication structures 1398 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1399 1400 // Complete cleaning used when class unloading is enabled. 1401 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1402 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1403 1404 // Redirty logged cards in the refinement queue. 1405 void redirty_logged_cards(); 1406 // Verification 1407 1408 // Perform any cleanup actions necessary before allowing a verification. 1409 virtual void prepare_for_verify(); 1410 1411 // Perform verification. 1412 1413 // vo == UsePrevMarking -> use "prev" marking information, 1414 // vo == UseNextMarking -> use "next" marking information 1415 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1416 // 1417 // NOTE: Only the "prev" marking information is guaranteed to be 1418 // consistent most of the time, so most calls to this should use 1419 // vo == UsePrevMarking. 1420 // Currently, there is only one case where this is called with 1421 // vo == UseNextMarking, which is to verify the "next" marking 1422 // information at the end of remark. 1423 // Currently there is only one place where this is called with 1424 // vo == UseFullMarking, which is to verify the marking during a 1425 // full GC. 1426 void verify(VerifyOption vo); 1427 1428 // WhiteBox testing support. 1429 virtual bool supports_concurrent_phase_control() const; 1430 virtual const char* const* concurrent_phases() const; 1431 virtual bool request_concurrent_phase(const char* phase); 1432 1433 // The methods below are here for convenience and dispatch the 1434 // appropriate method depending on value of the given VerifyOption 1435 // parameter. The values for that parameter, and their meanings, 1436 // are the same as those above. 1437 1438 bool is_obj_dead_cond(const oop obj, 1439 const HeapRegion* hr, 1440 const VerifyOption vo) const; 1441 1442 bool is_obj_dead_cond(const oop obj, 1443 const VerifyOption vo) const; 1444 1445 G1HeapSummary create_g1_heap_summary(); 1446 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1447 1448 // Printing 1449 private: 1450 void print_heap_regions() const; 1451 void print_regions_on(outputStream* st) const; 1452 1453 public: 1454 virtual void print_on(outputStream* st) const; 1455 virtual void print_extended_on(outputStream* st) const; 1456 virtual void print_on_error(outputStream* st) const; 1457 1458 virtual void print_gc_threads_on(outputStream* st) const; 1459 virtual void gc_threads_do(ThreadClosure* tc) const; 1460 1461 // Override 1462 void print_tracing_info() const; 1463 1464 // The following two methods are helpful for debugging RSet issues. 1465 void print_cset_rsets() PRODUCT_RETURN; 1466 void print_all_rsets() PRODUCT_RETURN; 1467 1468 public: 1469 size_t pending_card_num(); 1470 1471 protected: 1472 size_t _max_heap_capacity; 1473 }; 1474 1475 class G1ParEvacuateFollowersClosure : public VoidClosure { 1476 private: 1477 double _start_term; 1478 double _term_time; 1479 size_t _term_attempts; 1480 1481 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1482 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1483 protected: 1484 G1CollectedHeap* _g1h; 1485 G1ParScanThreadState* _par_scan_state; 1486 RefToScanQueueSet* _queues; 1487 ParallelTaskTerminator* _terminator; 1488 1489 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1490 RefToScanQueueSet* queues() { return _queues; } 1491 ParallelTaskTerminator* terminator() { return _terminator; } 1492 1493 public: 1494 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1495 G1ParScanThreadState* par_scan_state, 1496 RefToScanQueueSet* queues, 1497 ParallelTaskTerminator* terminator) 1498 : _g1h(g1h), _par_scan_state(par_scan_state), 1499 _queues(queues), _terminator(terminator), 1500 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1501 1502 void do_void(); 1503 1504 double term_time() const { return _term_time; } 1505 size_t term_attempts() const { return _term_attempts; } 1506 1507 private: 1508 inline bool offer_termination(); 1509 }; 1510 1511 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP