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/g1BiasedArray.hpp" 31 #include "gc/g1/g1CollectionSet.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1ConcurrentMark.hpp" 34 #include "gc/g1/g1EdenRegions.hpp" 35 #include "gc/g1/g1EvacFailure.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1HeapTransition.hpp" 38 #include "gc/g1/g1HeapVerifier.hpp" 39 #include "gc/g1/g1HRPrinter.hpp" 40 #include "gc/g1/g1InCSetState.hpp" 41 #include "gc/g1/g1MonitoringSupport.hpp" 42 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 43 #include "gc/g1/g1SurvivorRegions.hpp" 44 #include "gc/g1/g1YCTypes.hpp" 45 #include "gc/g1/heapRegionManager.hpp" 46 #include "gc/g1/heapRegionSet.hpp" 47 #include "gc/shared/barrierSet.hpp" 48 #include "gc/shared/collectedHeap.hpp" 49 #include "gc/shared/gcHeapSummary.hpp" 50 #include "gc/shared/plab.hpp" 51 #include "gc/shared/preservedMarks.hpp" 52 #include "gc/shared/softRefPolicy.hpp" 53 #include "memory/memRegion.hpp" 54 #include "services/memoryManager.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 ObjectClosure; 71 class SpaceClosure; 72 class CompactibleSpaceClosure; 73 class Space; 74 class G1CollectionSet; 75 class G1CollectorPolicy; 76 class G1Policy; 77 class G1HotCardCache; 78 class G1RemSet; 79 class G1YoungRemSetSamplingThread; 80 class HeapRegionRemSetIterator; 81 class G1ConcurrentMark; 82 class ConcurrentMarkThread; 83 class G1ConcurrentRefine; 84 class GenerationCounters; 85 class STWGCTimer; 86 class G1NewTracer; 87 class EvacuationFailedInfo; 88 class nmethod; 89 class Ticks; 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* _g1; 112 public: 113 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 114 bool do_object_b(oop p); 115 }; 116 117 class G1RegionMappingChangedListener : public G1MappingChangedListener { 118 private: 119 void reset_from_card_cache(uint start_idx, size_t num_regions); 120 public: 121 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 122 }; 123 124 class G1CollectedHeap : public CollectedHeap { 125 friend class G1FreeCollectionSetTask; 126 friend class VM_CollectForMetadataAllocation; 127 friend class VM_G1CollectForAllocation; 128 friend class VM_G1CollectFull; 129 friend class VMStructs; 130 friend class MutatorAllocRegion; 131 friend class G1FullCollector; 132 friend class G1GCAllocRegion; 133 friend class G1HeapVerifier; 134 135 // Closures used in implementation. 136 friend class G1ParScanThreadState; 137 friend class G1ParScanThreadStateSet; 138 friend class G1ParTask; 139 friend class G1PLABAllocator; 140 friend class G1PrepareCompactClosure; 141 142 // Other related classes. 143 friend class HeapRegionClaimer; 144 145 // Testing classes. 146 friend class G1CheckCSetFastTableClosure; 147 148 private: 149 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 150 151 WorkGang* _workers; 152 G1CollectorPolicy* _collector_policy; 153 154 SoftRefPolicy _soft_ref_policy; 155 156 GCMemoryManager _memory_manager; 157 GCMemoryManager _full_gc_memory_manager; 158 159 MemoryPool* _eden_pool; 160 MemoryPool* _survivor_pool; 161 MemoryPool* _old_pool; 162 163 static size_t _humongous_object_threshold_in_words; 164 165 // The secondary free list which contains regions that have been 166 // freed up during the cleanup process. This will be appended to 167 // the master free list when appropriate. 168 FreeRegionList _secondary_free_list; 169 170 // It keeps track of the old regions. 171 HeapRegionSet _old_set; 172 173 // It keeps track of the humongous regions. 174 HeapRegionSet _humongous_set; 175 176 virtual void initialize_serviceability(); 177 178 void eagerly_reclaim_humongous_regions(); 179 // Start a new incremental collection set for the next pause. 180 void start_new_collection_set(); 181 182 // The number of regions we could create by expansion. 183 uint _expansion_regions; 184 185 // The block offset table for the G1 heap. 186 G1BlockOffsetTable* _bot; 187 188 // Tears down the region sets / lists so that they are empty and the 189 // regions on the heap do not belong to a region set / list. The 190 // only exception is the humongous set which we leave unaltered. If 191 // free_list_only is true, it will only tear down the master free 192 // list. It is called before a Full GC (free_list_only == false) or 193 // before heap shrinking (free_list_only == true). 194 void tear_down_region_sets(bool free_list_only); 195 196 // Rebuilds the region sets / lists so that they are repopulated to 197 // reflect the contents of the heap. The only exception is the 198 // humongous set which was not torn down in the first place. If 199 // free_list_only is true, it will only rebuild the master free 200 // list. It is called after a Full GC (free_list_only == false) or 201 // after heap shrinking (free_list_only == true). 202 void rebuild_region_sets(bool free_list_only); 203 204 // Callback for region mapping changed events. 205 G1RegionMappingChangedListener _listener; 206 207 // The sequence of all heap regions in the heap. 208 HeapRegionManager _hrm; 209 210 // Manages all allocations with regions except humongous object allocations. 211 G1Allocator* _allocator; 212 213 // Manages all heap verification. 214 G1HeapVerifier* _verifier; 215 216 // Outside of GC pauses, the number of bytes used in all regions other 217 // than the current allocation region(s). 218 size_t _summary_bytes_used; 219 220 void increase_used(size_t bytes); 221 void decrease_used(size_t bytes); 222 223 void set_used(size_t bytes); 224 225 // Class that handles archive allocation ranges. 226 G1ArchiveAllocator* _archive_allocator; 227 228 // Statistics for each allocation context 229 AllocationContextStats _allocation_context_stats; 230 231 // GC allocation statistics policy for survivors. 232 G1EvacStats _survivor_evac_stats; 233 234 // GC allocation statistics policy for tenured objects. 235 G1EvacStats _old_evac_stats; 236 237 // It specifies whether we should attempt to expand the heap after a 238 // region allocation failure. If heap expansion fails we set this to 239 // false so that we don't re-attempt the heap expansion (it's likely 240 // that subsequent expansion attempts will also fail if one fails). 241 // Currently, it is only consulted during GC and it's reset at the 242 // start of each GC. 243 bool _expand_heap_after_alloc_failure; 244 245 // Helper for monitoring and management support. 246 G1MonitoringSupport* _g1mm; 247 248 // Records whether the region at the given index is (still) a 249 // candidate for eager reclaim. Only valid for humongous start 250 // regions; other regions have unspecified values. Humongous start 251 // regions are initialized at start of collection pause, with 252 // candidates removed from the set as they are found reachable from 253 // roots or the young generation. 254 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 255 protected: 256 bool default_value() const { return false; } 257 public: 258 void clear() { G1BiasedMappedArray<bool>::clear(); } 259 void set_candidate(uint region, bool value) { 260 set_by_index(region, value); 261 } 262 bool is_candidate(uint region) { 263 return get_by_index(region); 264 } 265 }; 266 267 HumongousReclaimCandidates _humongous_reclaim_candidates; 268 // Stores whether during humongous object registration we found candidate regions. 269 // If not, we can skip a few steps. 270 bool _has_humongous_reclaim_candidates; 271 272 volatile uint _gc_time_stamp; 273 274 G1HRPrinter _hr_printer; 275 276 // It decides whether an explicit GC should start a concurrent cycle 277 // instead of doing a STW GC. Currently, a concurrent cycle is 278 // explicitly started if: 279 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 280 // (b) cause == _g1_humongous_allocation 281 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 282 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 283 // (e) cause == _update_allocation_context_stats_inc 284 // (f) cause == _wb_conc_mark 285 bool should_do_concurrent_full_gc(GCCause::Cause cause); 286 287 // indicates whether we are in young or mixed GC mode 288 G1CollectorState _collector_state; 289 290 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 291 // concurrent cycles) we have started. 292 volatile uint _old_marking_cycles_started; 293 294 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 295 // concurrent cycles) we have completed. 296 volatile uint _old_marking_cycles_completed; 297 298 // This is a non-product method that is helpful for testing. It is 299 // called at the end of a GC and artificially expands the heap by 300 // allocating a number of dead regions. This way we can induce very 301 // frequent marking cycles and stress the cleanup / concurrent 302 // cleanup code more (as all the regions that will be allocated by 303 // this method will be found dead by the marking cycle). 304 void allocate_dummy_regions() PRODUCT_RETURN; 305 306 // Clear RSets after a compaction. It also resets the GC time stamps. 307 void clear_rsets_post_compaction(); 308 309 // If the HR printer is active, dump the state of the regions in the 310 // heap after a compaction. 311 void print_hrm_post_compaction(); 312 313 // Create a memory mapper for auxiliary data structures of the given size and 314 // translation factor. 315 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 316 size_t size, 317 size_t translation_factor); 318 319 static G1Policy* create_g1_policy(STWGCTimer* gc_timer); 320 321 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 322 323 // These are macros so that, if the assert fires, we get the correct 324 // line number, file, etc. 325 326 #define heap_locking_asserts_params(_extra_message_) \ 327 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 328 (_extra_message_), \ 329 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 330 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 331 BOOL_TO_STR(Thread::current()->is_VM_thread()) 332 333 #define assert_heap_locked() \ 334 do { \ 335 assert(Heap_lock->owned_by_self(), \ 336 heap_locking_asserts_params("should be holding the Heap_lock")); \ 337 } while (0) 338 339 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 340 do { \ 341 assert(Heap_lock->owned_by_self() || \ 342 (SafepointSynchronize::is_at_safepoint() && \ 343 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 344 heap_locking_asserts_params("should be holding the Heap_lock or " \ 345 "should be at a safepoint")); \ 346 } while (0) 347 348 #define assert_heap_locked_and_not_at_safepoint() \ 349 do { \ 350 assert(Heap_lock->owned_by_self() && \ 351 !SafepointSynchronize::is_at_safepoint(), \ 352 heap_locking_asserts_params("should be holding the Heap_lock and " \ 353 "should not be at a safepoint")); \ 354 } while (0) 355 356 #define assert_heap_not_locked() \ 357 do { \ 358 assert(!Heap_lock->owned_by_self(), \ 359 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 360 } while (0) 361 362 #define assert_heap_not_locked_and_not_at_safepoint() \ 363 do { \ 364 assert(!Heap_lock->owned_by_self() && \ 365 !SafepointSynchronize::is_at_safepoint(), \ 366 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 367 "should not be at a safepoint")); \ 368 } while (0) 369 370 #define assert_at_safepoint(_should_be_vm_thread_) \ 371 do { \ 372 assert(SafepointSynchronize::is_at_safepoint() && \ 373 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 374 heap_locking_asserts_params("should be at a safepoint")); \ 375 } while (0) 376 377 #define assert_not_at_safepoint() \ 378 do { \ 379 assert(!SafepointSynchronize::is_at_safepoint(), \ 380 heap_locking_asserts_params("should not be at a safepoint")); \ 381 } while (0) 382 383 protected: 384 385 // The young region list. 386 G1EdenRegions _eden; 387 G1SurvivorRegions _survivor; 388 389 STWGCTimer* _gc_timer_stw; 390 391 G1NewTracer* _gc_tracer_stw; 392 393 // The current policy object for the collector. 394 G1Policy* _g1_policy; 395 G1HeapSizingPolicy* _heap_sizing_policy; 396 397 G1CollectionSet _collection_set; 398 399 // This is the second level of trying to allocate a new region. If 400 // new_region() didn't find a region on the free_list, this call will 401 // check whether there's anything available on the 402 // secondary_free_list and/or wait for more regions to appear on 403 // that list, if _free_regions_coming is set. 404 HeapRegion* new_region_try_secondary_free_list(bool is_old); 405 406 // Try to allocate a single non-humongous HeapRegion sufficient for 407 // an allocation of the given word_size. If do_expand is true, 408 // attempt to expand the heap if necessary to satisfy the allocation 409 // request. If the region is to be used as an old region or for a 410 // humongous object, set is_old to true. If not, to false. 411 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 412 413 // Initialize a contiguous set of free regions of length num_regions 414 // and starting at index first so that they appear as a single 415 // humongous region. 416 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 417 uint num_regions, 418 size_t word_size, 419 AllocationContext_t context); 420 421 // Attempt to allocate a humongous object of the given size. Return 422 // NULL if unsuccessful. 423 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 424 425 // The following two methods, allocate_new_tlab() and 426 // mem_allocate(), are the two main entry points from the runtime 427 // into the G1's allocation routines. They have the following 428 // assumptions: 429 // 430 // * They should both be called outside safepoints. 431 // 432 // * They should both be called without holding the Heap_lock. 433 // 434 // * All allocation requests for new TLABs should go to 435 // allocate_new_tlab(). 436 // 437 // * All non-TLAB allocation requests should go to mem_allocate(). 438 // 439 // * If either call cannot satisfy the allocation request using the 440 // current allocating region, they will try to get a new one. If 441 // this fails, they will attempt to do an evacuation pause and 442 // retry the allocation. 443 // 444 // * If all allocation attempts fail, even after trying to schedule 445 // an evacuation pause, allocate_new_tlab() will return NULL, 446 // whereas mem_allocate() will attempt a heap expansion and/or 447 // schedule a Full GC. 448 // 449 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 450 // should never be called with word_size being humongous. All 451 // humongous allocation requests should go to mem_allocate() which 452 // will satisfy them with a special path. 453 454 virtual HeapWord* allocate_new_tlab(size_t word_size); 455 456 virtual HeapWord* mem_allocate(size_t word_size, 457 bool* gc_overhead_limit_was_exceeded); 458 459 // First-level mutator allocation attempt: try to allocate out of 460 // the mutator alloc region without taking the Heap_lock. This 461 // should only be used for non-humongous allocations. 462 inline HeapWord* attempt_allocation(size_t word_size); 463 464 // Second-level mutator allocation attempt: take the Heap_lock and 465 // retry the allocation attempt, potentially scheduling a GC 466 // pause. This should only be used for non-humongous allocations. 467 HeapWord* attempt_allocation_slow(size_t word_size, 468 AllocationContext_t context); 469 470 // Takes the Heap_lock and attempts a humongous allocation. It can 471 // potentially schedule a GC pause. 472 HeapWord* attempt_allocation_humongous(size_t word_size); 473 474 // Allocation attempt that should be called during safepoints (e.g., 475 // at the end of a successful GC). expect_null_mutator_alloc_region 476 // specifies whether the mutator alloc region is expected to be NULL 477 // or not. 478 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 479 AllocationContext_t context, 480 bool expect_null_mutator_alloc_region); 481 482 // These methods are the "callbacks" from the G1AllocRegion class. 483 484 // For mutator alloc regions. 485 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 486 void retire_mutator_alloc_region(HeapRegion* alloc_region, 487 size_t allocated_bytes); 488 489 // For GC alloc regions. 490 bool has_more_regions(InCSetState dest); 491 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 492 void retire_gc_alloc_region(HeapRegion* alloc_region, 493 size_t allocated_bytes, InCSetState dest); 494 495 // - if explicit_gc is true, the GC is for a System.gc() etc, 496 // otherwise it's for a failed allocation. 497 // - if clear_all_soft_refs is true, all soft references should be 498 // cleared during the GC. 499 // - it returns false if it is unable to do the collection due to the 500 // GC locker being active, true otherwise. 501 bool do_full_collection(bool explicit_gc, 502 bool clear_all_soft_refs); 503 504 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 505 virtual void do_full_collection(bool clear_all_soft_refs); 506 507 // Resize the heap if necessary after a full collection. 508 void resize_if_necessary_after_full_collection(); 509 510 // Callback from VM_G1CollectForAllocation operation. 511 // This function does everything necessary/possible to satisfy a 512 // failed allocation request (including collection, expansion, etc.) 513 HeapWord* satisfy_failed_allocation(size_t word_size, 514 AllocationContext_t context, 515 bool* succeeded); 516 private: 517 // Internal helpers used during full GC to split it up to 518 // increase readability. 519 void abort_concurrent_cycle(); 520 void verify_before_full_collection(bool explicit_gc); 521 void prepare_heap_for_full_collection(); 522 void prepare_heap_for_mutators(); 523 void abort_refinement(); 524 void verify_after_full_collection(); 525 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 526 527 // Helper method for satisfy_failed_allocation() 528 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 529 AllocationContext_t context, 530 bool do_gc, 531 bool clear_all_soft_refs, 532 bool expect_null_mutator_alloc_region, 533 bool* gc_succeeded); 534 535 protected: 536 // Attempting to expand the heap sufficiently 537 // to support an allocation of the given "word_size". If 538 // successful, perform the allocation and return the address of the 539 // allocated block, or else "NULL". 540 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 541 542 // Preserve any referents discovered by concurrent marking that have not yet been 543 // copied by the STW pause. 544 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 545 // Process any reference objects discovered during 546 // an incremental evacuation pause. 547 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 548 549 // Enqueue any remaining discovered references 550 // after processing. 551 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 552 553 // Merges the information gathered on a per-thread basis for all worker threads 554 // during GC into global variables. 555 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 556 public: 557 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 558 559 WorkGang* workers() const { return _workers; } 560 561 G1Allocator* allocator() { 562 return _allocator; 563 } 564 565 G1HeapVerifier* verifier() { 566 return _verifier; 567 } 568 569 G1MonitoringSupport* g1mm() { 570 assert(_g1mm != NULL, "should have been initialized"); 571 return _g1mm; 572 } 573 574 // Expand the garbage-first heap by at least the given size (in bytes!). 575 // Returns true if the heap was expanded by the requested amount; 576 // false otherwise. 577 // (Rounds up to a HeapRegion boundary.) 578 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 579 580 // Returns the PLAB statistics for a given destination. 581 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 582 583 // Determines PLAB size for a given destination. 584 inline size_t desired_plab_sz(InCSetState dest); 585 586 inline AllocationContextStats& allocation_context_stats(); 587 588 // Do anything common to GC's. 589 void gc_prologue(bool full); 590 void gc_epilogue(bool full); 591 592 // Modify the reclaim candidate set and test for presence. 593 // These are only valid for starts_humongous regions. 594 inline void set_humongous_reclaim_candidate(uint region, bool value); 595 inline bool is_humongous_reclaim_candidate(uint region); 596 597 // Remove from the reclaim candidate set. Also remove from the 598 // collection set so that later encounters avoid the slow path. 599 inline void set_humongous_is_live(oop obj); 600 601 // Register the given region to be part of the collection set. 602 inline void register_humongous_region_with_cset(uint index); 603 // Register regions with humongous objects (actually on the start region) in 604 // the in_cset_fast_test table. 605 void register_humongous_regions_with_cset(); 606 // We register a region with the fast "in collection set" test. We 607 // simply set to true the array slot corresponding to this region. 608 void register_young_region_with_cset(HeapRegion* r) { 609 _in_cset_fast_test.set_in_young(r->hrm_index()); 610 } 611 void register_old_region_with_cset(HeapRegion* r) { 612 _in_cset_fast_test.set_in_old(r->hrm_index()); 613 } 614 inline void register_ext_region_with_cset(HeapRegion* r) { 615 _in_cset_fast_test.set_ext(r->hrm_index()); 616 } 617 void clear_in_cset(const HeapRegion* hr) { 618 _in_cset_fast_test.clear(hr); 619 } 620 621 void clear_cset_fast_test() { 622 _in_cset_fast_test.clear(); 623 } 624 625 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 626 627 // This is called at the start of either a concurrent cycle or a Full 628 // GC to update the number of old marking cycles started. 629 void increment_old_marking_cycles_started(); 630 631 // This is called at the end of either a concurrent cycle or a Full 632 // GC to update the number of old marking cycles completed. Those two 633 // can happen in a nested fashion, i.e., we start a concurrent 634 // cycle, a Full GC happens half-way through it which ends first, 635 // and then the cycle notices that a Full GC happened and ends 636 // too. The concurrent parameter is a boolean to help us do a bit 637 // tighter consistency checking in the method. If concurrent is 638 // false, the caller is the inner caller in the nesting (i.e., the 639 // Full GC). If concurrent is true, the caller is the outer caller 640 // in this nesting (i.e., the concurrent cycle). Further nesting is 641 // not currently supported. The end of this call also notifies 642 // the FullGCCount_lock in case a Java thread is waiting for a full 643 // GC to happen (e.g., it called System.gc() with 644 // +ExplicitGCInvokesConcurrent). 645 void increment_old_marking_cycles_completed(bool concurrent); 646 647 uint old_marking_cycles_completed() { 648 return _old_marking_cycles_completed; 649 } 650 651 G1HRPrinter* hr_printer() { return &_hr_printer; } 652 653 // Allocates a new heap region instance. 654 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 655 656 // Allocate the highest free region in the reserved heap. This will commit 657 // regions as necessary. 658 HeapRegion* alloc_highest_free_region(); 659 660 // Frees a non-humongous region by initializing its contents and 661 // adding it to the free list that's passed as a parameter (this is 662 // usually a local list which will be appended to the master free 663 // list later). The used bytes of freed regions are accumulated in 664 // pre_used. If skip_remset is true, the region's RSet will not be freed 665 // up. If skip_hot_card_cache is true, the region's hot card cache will not 666 // be freed up. The assumption is that this will be done later. 667 // The locked parameter indicates if the caller has already taken 668 // care of proper synchronization. This may allow some optimizations. 669 void free_region(HeapRegion* hr, 670 FreeRegionList* free_list, 671 bool skip_remset, 672 bool skip_hot_card_cache = false, 673 bool locked = false); 674 675 // It dirties the cards that cover the block so that the post 676 // write barrier never queues anything when updating objects on this 677 // block. It is assumed (and in fact we assert) that the block 678 // belongs to a young region. 679 inline void dirty_young_block(HeapWord* start, size_t word_size); 680 681 // Frees a humongous region by collapsing it into individual regions 682 // and calling free_region() for each of them. The freed regions 683 // will be added to the free list that's passed as a parameter (this 684 // is usually a local list which will be appended to the master free 685 // list later). The used bytes of freed regions are accumulated in 686 // pre_used. If skip_remset is true, the region's RSet will not be freed 687 // up. The assumption is that this will be done later. 688 void free_humongous_region(HeapRegion* hr, 689 FreeRegionList* free_list, 690 bool skip_remset); 691 692 // Facility for allocating in 'archive' regions in high heap memory and 693 // recording the allocated ranges. These should all be called from the 694 // VM thread at safepoints, without the heap lock held. They can be used 695 // to create and archive a set of heap regions which can be mapped at the 696 // same fixed addresses in a subsequent JVM invocation. 697 void begin_archive_alloc_range(bool open = false); 698 699 // Check if the requested size would be too large for an archive allocation. 700 bool is_archive_alloc_too_large(size_t word_size); 701 702 // Allocate memory of the requested size from the archive region. This will 703 // return NULL if the size is too large or if no memory is available. It 704 // does not trigger a garbage collection. 705 HeapWord* archive_mem_allocate(size_t word_size); 706 707 // Optionally aligns the end address and returns the allocated ranges in 708 // an array of MemRegions in order of ascending addresses. 709 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 710 size_t end_alignment_in_bytes = 0); 711 712 // Facility for allocating a fixed range within the heap and marking 713 // the containing regions as 'archive'. For use at JVM init time, when the 714 // caller may mmap archived heap data at the specified range(s). 715 // Verify that the MemRegions specified in the argument array are within the 716 // reserved heap. 717 bool check_archive_addresses(MemRegion* range, size_t count); 718 719 // Commit the appropriate G1 regions containing the specified MemRegions 720 // and mark them as 'archive' regions. The regions in the array must be 721 // non-overlapping and in order of ascending address. 722 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 723 724 // Insert any required filler objects in the G1 regions around the specified 725 // ranges to make the regions parseable. This must be called after 726 // alloc_archive_regions, and after class loading has occurred. 727 void fill_archive_regions(MemRegion* range, size_t count); 728 729 // For each of the specified MemRegions, uncommit the containing G1 regions 730 // which had been allocated by alloc_archive_regions. This should be called 731 // rather than fill_archive_regions at JVM init time if the archive file 732 // mapping failed, with the same non-overlapping and sorted MemRegion array. 733 void dealloc_archive_regions(MemRegion* range, size_t count); 734 735 protected: 736 737 // Shrink the garbage-first heap by at most the given size (in bytes!). 738 // (Rounds down to a HeapRegion boundary.) 739 virtual void shrink(size_t expand_bytes); 740 void shrink_helper(size_t expand_bytes); 741 742 #if TASKQUEUE_STATS 743 static void print_taskqueue_stats_hdr(outputStream* const st); 744 void print_taskqueue_stats() const; 745 void reset_taskqueue_stats(); 746 #endif // TASKQUEUE_STATS 747 748 // Schedule the VM operation that will do an evacuation pause to 749 // satisfy an allocation request of word_size. *succeeded will 750 // return whether the VM operation was successful (it did do an 751 // evacuation pause) or not (another thread beat us to it or the GC 752 // locker was active). Given that we should not be holding the 753 // Heap_lock when we enter this method, we will pass the 754 // gc_count_before (i.e., total_collections()) as a parameter since 755 // it has to be read while holding the Heap_lock. Currently, both 756 // methods that call do_collection_pause() release the Heap_lock 757 // before the call, so it's easy to read gc_count_before just before. 758 HeapWord* do_collection_pause(size_t word_size, 759 uint gc_count_before, 760 bool* succeeded, 761 GCCause::Cause gc_cause); 762 763 void wait_for_root_region_scanning(); 764 765 // The guts of the incremental collection pause, executed by the vm 766 // thread. It returns false if it is unable to do the collection due 767 // to the GC locker being active, true otherwise 768 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 769 770 // Actually do the work of evacuating the collection set. 771 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 772 773 void pre_evacuate_collection_set(); 774 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 775 776 // Print the header for the per-thread termination statistics. 777 static void print_termination_stats_hdr(); 778 // Print actual per-thread termination statistics. 779 void print_termination_stats(uint worker_id, 780 double elapsed_ms, 781 double strong_roots_ms, 782 double term_ms, 783 size_t term_attempts, 784 size_t alloc_buffer_waste, 785 size_t undo_waste) const; 786 // Update object copying statistics. 787 void record_obj_copy_mem_stats(); 788 789 // The hot card cache for remembered set insertion optimization. 790 G1HotCardCache* _hot_card_cache; 791 792 // The g1 remembered set of the heap. 793 G1RemSet* _g1_rem_set; 794 795 // A set of cards that cover the objects for which the Rsets should be updated 796 // concurrently after the collection. 797 DirtyCardQueueSet _dirty_card_queue_set; 798 799 // After a collection pause, convert the regions in the collection set into free 800 // regions. 801 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 802 803 // Abandon the current collection set without recording policy 804 // statistics or updating free lists. 805 void abandon_collection_set(G1CollectionSet* collection_set); 806 807 // The concurrent marker (and the thread it runs in.) 808 G1ConcurrentMark* _cm; 809 ConcurrentMarkThread* _cmThread; 810 811 // The concurrent refiner. 812 G1ConcurrentRefine* _cr; 813 814 // The parallel task queues 815 RefToScanQueueSet *_task_queues; 816 817 // True iff a evacuation has failed in the current collection. 818 bool _evacuation_failed; 819 820 EvacuationFailedInfo* _evacuation_failed_info_array; 821 822 // Failed evacuations cause some logical from-space objects to have 823 // forwarding pointers to themselves. Reset them. 824 void remove_self_forwarding_pointers(); 825 826 // Restore the objects in the regions in the collection set after an 827 // evacuation failure. 828 void restore_after_evac_failure(); 829 830 PreservedMarksSet _preserved_marks_set; 831 832 // Preserve the mark of "obj", if necessary, in preparation for its mark 833 // word being overwritten with a self-forwarding-pointer. 834 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 835 836 #ifndef PRODUCT 837 // Support for forcing evacuation failures. Analogous to 838 // PromotionFailureALot for the other collectors. 839 840 // Records whether G1EvacuationFailureALot should be in effect 841 // for the current GC 842 bool _evacuation_failure_alot_for_current_gc; 843 844 // Used to record the GC number for interval checking when 845 // determining whether G1EvaucationFailureALot is in effect 846 // for the current GC. 847 size_t _evacuation_failure_alot_gc_number; 848 849 // Count of the number of evacuations between failures. 850 volatile size_t _evacuation_failure_alot_count; 851 852 // Set whether G1EvacuationFailureALot should be in effect 853 // for the current GC (based upon the type of GC and which 854 // command line flags are set); 855 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 856 bool during_initial_mark, 857 bool during_marking); 858 859 inline void set_evacuation_failure_alot_for_current_gc(); 860 861 // Return true if it's time to cause an evacuation failure. 862 inline bool evacuation_should_fail(); 863 864 // Reset the G1EvacuationFailureALot counters. Should be called at 865 // the end of an evacuation pause in which an evacuation failure occurred. 866 inline void reset_evacuation_should_fail(); 867 #endif // !PRODUCT 868 869 // ("Weak") Reference processing support. 870 // 871 // G1 has 2 instances of the reference processor class. One 872 // (_ref_processor_cm) handles reference object discovery 873 // and subsequent processing during concurrent marking cycles. 874 // 875 // The other (_ref_processor_stw) handles reference object 876 // discovery and processing during full GCs and incremental 877 // evacuation pauses. 878 // 879 // During an incremental pause, reference discovery will be 880 // temporarily disabled for _ref_processor_cm and will be 881 // enabled for _ref_processor_stw. At the end of the evacuation 882 // pause references discovered by _ref_processor_stw will be 883 // processed and discovery will be disabled. The previous 884 // setting for reference object discovery for _ref_processor_cm 885 // will be re-instated. 886 // 887 // At the start of marking: 888 // * Discovery by the CM ref processor is verified to be inactive 889 // and it's discovered lists are empty. 890 // * Discovery by the CM ref processor is then enabled. 891 // 892 // At the end of marking: 893 // * Any references on the CM ref processor's discovered 894 // lists are processed (possibly MT). 895 // 896 // At the start of full GC we: 897 // * Disable discovery by the CM ref processor and 898 // empty CM ref processor's discovered lists 899 // (without processing any entries). 900 // * Verify that the STW ref processor is inactive and it's 901 // discovered lists are empty. 902 // * Temporarily set STW ref processor discovery as single threaded. 903 // * Temporarily clear the STW ref processor's _is_alive_non_header 904 // field. 905 // * Finally enable discovery by the STW ref processor. 906 // 907 // The STW ref processor is used to record any discovered 908 // references during the full GC. 909 // 910 // At the end of a full GC we: 911 // * Enqueue any reference objects discovered by the STW ref processor 912 // that have non-live referents. This has the side-effect of 913 // making the STW ref processor inactive by disabling discovery. 914 // * Verify that the CM ref processor is still inactive 915 // and no references have been placed on it's discovered 916 // lists (also checked as a precondition during initial marking). 917 918 // The (stw) reference processor... 919 ReferenceProcessor* _ref_processor_stw; 920 921 // During reference object discovery, the _is_alive_non_header 922 // closure (if non-null) is applied to the referent object to 923 // determine whether the referent is live. If so then the 924 // reference object does not need to be 'discovered' and can 925 // be treated as a regular oop. This has the benefit of reducing 926 // the number of 'discovered' reference objects that need to 927 // be processed. 928 // 929 // Instance of the is_alive closure for embedding into the 930 // STW reference processor as the _is_alive_non_header field. 931 // Supplying a value for the _is_alive_non_header field is 932 // optional but doing so prevents unnecessary additions to 933 // the discovered lists during reference discovery. 934 G1STWIsAliveClosure _is_alive_closure_stw; 935 936 // The (concurrent marking) reference processor... 937 ReferenceProcessor* _ref_processor_cm; 938 939 // Instance of the concurrent mark is_alive closure for embedding 940 // into the Concurrent Marking reference processor as the 941 // _is_alive_non_header field. Supplying a value for the 942 // _is_alive_non_header field is optional but doing so prevents 943 // unnecessary additions to the discovered lists during reference 944 // discovery. 945 G1CMIsAliveClosure _is_alive_closure_cm; 946 947 volatile bool _free_regions_coming; 948 949 public: 950 951 RefToScanQueue *task_queue(uint i) const; 952 953 uint num_task_queues() const; 954 955 // A set of cards where updates happened during the GC 956 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 957 958 // Create a G1CollectedHeap with the specified policy. 959 // Must call the initialize method afterwards. 960 // May not return if something goes wrong. 961 G1CollectedHeap(G1CollectorPolicy* policy); 962 963 private: 964 jint initialize_concurrent_refinement(); 965 jint initialize_young_gen_sampling_thread(); 966 public: 967 // Initialize the G1CollectedHeap to have the initial and 968 // maximum sizes and remembered and barrier sets 969 // specified by the policy object. 970 jint initialize(); 971 972 virtual void stop(); 973 virtual void safepoint_synchronize_begin(); 974 virtual void safepoint_synchronize_end(); 975 976 // Return the (conservative) maximum heap alignment for any G1 heap 977 static size_t conservative_max_heap_alignment(); 978 979 // Does operations required after initialization has been done. 980 void post_initialize(); 981 982 // Initialize weak reference processing. 983 void ref_processing_init(); 984 985 virtual Name kind() const { 986 return CollectedHeap::G1CollectedHeap; 987 } 988 989 virtual const char* name() const { 990 return "G1"; 991 } 992 993 const G1CollectorState* collector_state() const { return &_collector_state; } 994 G1CollectorState* collector_state() { return &_collector_state; } 995 996 // The current policy object for the collector. 997 G1Policy* g1_policy() const { return _g1_policy; } 998 999 const G1CollectionSet* collection_set() const { return &_collection_set; } 1000 G1CollectionSet* collection_set() { return &_collection_set; } 1001 1002 virtual CollectorPolicy* collector_policy() const; 1003 1004 virtual SoftRefPolicy* soft_ref_policy(); 1005 1006 // Adaptive size policy. No such thing for g1. 1007 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1008 1009 virtual GrowableArray<GCMemoryManager*> memory_managers(); 1010 virtual GrowableArray<MemoryPool*> memory_pools(); 1011 1012 // The rem set and barrier set. 1013 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1014 1015 // Try to minimize the remembered set. 1016 void scrub_rem_set(); 1017 1018 uint get_gc_time_stamp() { 1019 return _gc_time_stamp; 1020 } 1021 1022 inline void reset_gc_time_stamp(); 1023 1024 void check_gc_time_stamps() PRODUCT_RETURN; 1025 1026 inline void increment_gc_time_stamp(); 1027 1028 // Reset the given region's GC timestamp. If it's starts humongous, 1029 // also reset the GC timestamp of its corresponding 1030 // continues humongous regions too. 1031 void reset_gc_time_stamps(HeapRegion* hr); 1032 1033 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1034 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1035 1036 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1037 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1038 1039 // The shared block offset table array. 1040 G1BlockOffsetTable* bot() const { return _bot; } 1041 1042 // Reference Processing accessors 1043 1044 // The STW reference processor.... 1045 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1046 1047 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1048 1049 // The Concurrent Marking reference processor... 1050 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1051 1052 size_t unused_committed_regions_in_bytes() const; 1053 virtual size_t capacity() const; 1054 virtual size_t used() const; 1055 // This should be called when we're not holding the heap lock. The 1056 // result might be a bit inaccurate. 1057 size_t used_unlocked() const; 1058 size_t recalculate_used() const; 1059 1060 // These virtual functions do the actual allocation. 1061 // Some heaps may offer a contiguous region for shared non-blocking 1062 // allocation, via inlined code (by exporting the address of the top and 1063 // end fields defining the extent of the contiguous allocation region.) 1064 // But G1CollectedHeap doesn't yet support this. 1065 1066 virtual bool is_maximal_no_gc() const { 1067 return _hrm.available() == 0; 1068 } 1069 1070 // Returns whether there are any regions left in the heap for allocation. 1071 bool has_regions_left_for_allocation() const { 1072 return !is_maximal_no_gc() || num_free_regions() != 0; 1073 } 1074 1075 // The current number of regions in the heap. 1076 uint num_regions() const { return _hrm.length(); } 1077 1078 // The max number of regions in the heap. 1079 uint max_regions() const { return _hrm.max_length(); } 1080 1081 // The number of regions that are completely free. 1082 uint num_free_regions() const { return _hrm.num_free_regions(); } 1083 1084 MemoryUsage get_auxiliary_data_memory_usage() const { 1085 return _hrm.get_auxiliary_data_memory_usage(); 1086 } 1087 1088 // The number of regions that are not completely free. 1089 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1090 1091 #ifdef ASSERT 1092 bool is_on_master_free_list(HeapRegion* hr) { 1093 return _hrm.is_free(hr); 1094 } 1095 #endif // ASSERT 1096 1097 // Wrapper for the region list operations that can be called from 1098 // methods outside this class. 1099 1100 void secondary_free_list_add(FreeRegionList* list) { 1101 _secondary_free_list.add_ordered(list); 1102 } 1103 1104 void append_secondary_free_list() { 1105 _hrm.insert_list_into_free_list(&_secondary_free_list); 1106 } 1107 1108 void append_secondary_free_list_if_not_empty_with_lock() { 1109 // If the secondary free list looks empty there's no reason to 1110 // take the lock and then try to append it. 1111 if (!_secondary_free_list.is_empty()) { 1112 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1113 append_secondary_free_list(); 1114 } 1115 } 1116 1117 inline void old_set_add(HeapRegion* hr); 1118 inline void old_set_remove(HeapRegion* hr); 1119 1120 size_t non_young_capacity_bytes() { 1121 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1122 } 1123 1124 void set_free_regions_coming(); 1125 void reset_free_regions_coming(); 1126 bool free_regions_coming() { return _free_regions_coming; } 1127 void wait_while_free_regions_coming(); 1128 1129 // Determine whether the given region is one that we are using as an 1130 // old GC alloc region. 1131 bool is_old_gc_alloc_region(HeapRegion* hr); 1132 1133 // Perform a collection of the heap; intended for use in implementing 1134 // "System.gc". This probably implies as full a collection as the 1135 // "CollectedHeap" supports. 1136 virtual void collect(GCCause::Cause cause); 1137 1138 virtual bool copy_allocation_context_stats(const jint* contexts, 1139 jlong* totals, 1140 jbyte* accuracy, 1141 jint len); 1142 1143 // True iff an evacuation has failed in the most-recent collection. 1144 bool evacuation_failed() { return _evacuation_failed; } 1145 1146 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1147 void prepend_to_freelist(FreeRegionList* list); 1148 void decrement_summary_bytes(size_t bytes); 1149 1150 virtual bool is_in(const void* p) const; 1151 #ifdef ASSERT 1152 // Returns whether p is in one of the available areas of the heap. Slow but 1153 // extensive version. 1154 bool is_in_exact(const void* p) const; 1155 #endif 1156 1157 // Return "TRUE" iff the given object address is within the collection 1158 // set. Assumes that the reference points into the heap. 1159 inline bool is_in_cset(const HeapRegion *hr); 1160 inline bool is_in_cset(oop obj); 1161 inline bool is_in_cset(HeapWord* addr); 1162 1163 inline bool is_in_cset_or_humongous(const oop obj); 1164 1165 private: 1166 // This array is used for a quick test on whether a reference points into 1167 // the collection set or not. Each of the array's elements denotes whether the 1168 // corresponding region is in the collection set or not. 1169 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1170 1171 public: 1172 1173 inline InCSetState in_cset_state(const oop obj); 1174 1175 // Return "TRUE" iff the given object address is in the reserved 1176 // region of g1. 1177 bool is_in_g1_reserved(const void* p) const { 1178 return _hrm.reserved().contains(p); 1179 } 1180 1181 // Returns a MemRegion that corresponds to the space that has been 1182 // reserved for the heap 1183 MemRegion g1_reserved() const { 1184 return _hrm.reserved(); 1185 } 1186 1187 virtual bool is_in_closed_subset(const void* p) const; 1188 1189 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1190 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1191 } 1192 1193 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1194 1195 // Iteration functions. 1196 1197 // Iterate over all objects, calling "cl.do_object" on each. 1198 virtual void object_iterate(ObjectClosure* cl); 1199 1200 virtual void safe_object_iterate(ObjectClosure* cl) { 1201 object_iterate(cl); 1202 } 1203 1204 // Iterate over heap regions, in address order, terminating the 1205 // iteration early if the "do_heap_region" method returns "true". 1206 void heap_region_iterate(HeapRegionClosure* blk) const; 1207 1208 // Return the region with the given index. It assumes the index is valid. 1209 inline HeapRegion* region_at(uint index) const; 1210 1211 // Return the next region (by index) that is part of the same 1212 // humongous object that hr is part of. 1213 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1214 1215 // Calculate the region index of the given address. Given address must be 1216 // within the heap. 1217 inline uint addr_to_region(HeapWord* addr) const; 1218 1219 inline HeapWord* bottom_addr_for_region(uint index) const; 1220 1221 // Two functions to iterate over the heap regions in parallel. Threads 1222 // compete using the HeapRegionClaimer to claim the regions before 1223 // applying the closure on them. 1224 // The _from_worker_offset version uses the HeapRegionClaimer and 1225 // the worker id to calculate a start offset to prevent all workers to 1226 // start from the point. 1227 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1228 HeapRegionClaimer* hrclaimer, 1229 uint worker_id) const; 1230 1231 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1232 HeapRegionClaimer* hrclaimer) const; 1233 1234 // Iterate over the regions (if any) in the current collection set. 1235 void collection_set_iterate(HeapRegionClosure* blk); 1236 1237 // Iterate over the regions (if any) in the current collection set. Starts the 1238 // iteration over the entire collection set so that the start regions of a given 1239 // worker id over the set active_workers are evenly spread across the set of 1240 // collection set regions. 1241 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1242 1243 // Returns the HeapRegion that contains addr. addr must not be NULL. 1244 template <class T> 1245 inline HeapRegion* heap_region_containing(const T addr) const; 1246 1247 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1248 // each address in the (reserved) heap is a member of exactly 1249 // one block. The defining characteristic of a block is that it is 1250 // possible to find its size, and thus to progress forward to the next 1251 // block. (Blocks may be of different sizes.) Thus, blocks may 1252 // represent Java objects, or they might be free blocks in a 1253 // free-list-based heap (or subheap), as long as the two kinds are 1254 // distinguishable and the size of each is determinable. 1255 1256 // Returns the address of the start of the "block" that contains the 1257 // address "addr". We say "blocks" instead of "object" since some heaps 1258 // may not pack objects densely; a chunk may either be an object or a 1259 // non-object. 1260 virtual HeapWord* block_start(const void* addr) const; 1261 1262 // Requires "addr" to be the start of a chunk, and returns its size. 1263 // "addr + size" is required to be the start of a new chunk, or the end 1264 // of the active area of the heap. 1265 virtual size_t block_size(const HeapWord* addr) const; 1266 1267 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1268 // the block is an object. 1269 virtual bool block_is_obj(const HeapWord* addr) const; 1270 1271 // Section on thread-local allocation buffers (TLABs) 1272 // See CollectedHeap for semantics. 1273 1274 bool supports_tlab_allocation() const; 1275 size_t tlab_capacity(Thread* ignored) const; 1276 size_t tlab_used(Thread* ignored) const; 1277 size_t max_tlab_size() const; 1278 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1279 1280 inline bool is_in_young(const oop obj); 1281 1282 // Returns "true" iff the given word_size is "very large". 1283 static bool is_humongous(size_t word_size) { 1284 // Note this has to be strictly greater-than as the TLABs 1285 // are capped at the humongous threshold and we want to 1286 // ensure that we don't try to allocate a TLAB as 1287 // humongous and that we don't allocate a humongous 1288 // object in a TLAB. 1289 return word_size > _humongous_object_threshold_in_words; 1290 } 1291 1292 // Returns the humongous threshold for a specific region size 1293 static size_t humongous_threshold_for(size_t region_size) { 1294 return (region_size / 2); 1295 } 1296 1297 // Returns the number of regions the humongous object of the given word size 1298 // requires. 1299 static size_t humongous_obj_size_in_regions(size_t word_size); 1300 1301 // Print the maximum heap capacity. 1302 virtual size_t max_capacity() const; 1303 1304 virtual jlong millis_since_last_gc(); 1305 1306 1307 // Convenience function to be used in situations where the heap type can be 1308 // asserted to be this type. 1309 static G1CollectedHeap* heap(); 1310 1311 void set_region_short_lived_locked(HeapRegion* hr); 1312 // add appropriate methods for any other surv rate groups 1313 1314 const G1SurvivorRegions* survivor() const { return &_survivor; } 1315 1316 uint survivor_regions_count() const { 1317 return _survivor.length(); 1318 } 1319 1320 uint eden_regions_count() const { 1321 return _eden.length(); 1322 } 1323 1324 uint young_regions_count() const { 1325 return _eden.length() + _survivor.length(); 1326 } 1327 1328 uint old_regions_count() const { return _old_set.length(); } 1329 1330 uint humongous_regions_count() const { return _humongous_set.length(); } 1331 1332 #ifdef ASSERT 1333 bool check_young_list_empty(); 1334 #endif 1335 1336 // *** Stuff related to concurrent marking. It's not clear to me that so 1337 // many of these need to be public. 1338 1339 // The functions below are helper functions that a subclass of 1340 // "CollectedHeap" can use in the implementation of its virtual 1341 // functions. 1342 // This performs a concurrent marking of the live objects in a 1343 // bitmap off to the side. 1344 void doConcurrentMark(); 1345 1346 bool isMarkedNext(oop obj) const; 1347 1348 // Determine if an object is dead, given the object and also 1349 // the region to which the object belongs. An object is dead 1350 // iff a) it was not allocated since the last mark, b) it 1351 // is not marked, and c) it is not in an archive region. 1352 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1353 return 1354 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1355 !hr->is_archive(); 1356 } 1357 1358 // This function returns true when an object has been 1359 // around since the previous marking and hasn't yet 1360 // been marked during this marking, and is not in an archive region. 1361 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1362 return 1363 !hr->obj_allocated_since_next_marking(obj) && 1364 !isMarkedNext(obj) && 1365 !hr->is_archive(); 1366 } 1367 1368 // Determine if an object is dead, given only the object itself. 1369 // This will find the region to which the object belongs and 1370 // then call the region version of the same function. 1371 1372 // Added if it is NULL it isn't dead. 1373 1374 inline bool is_obj_dead(const oop obj) const; 1375 1376 inline bool is_obj_ill(const oop obj) const; 1377 1378 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1379 inline bool is_obj_dead_full(const oop obj) const; 1380 1381 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1382 1383 // Refinement 1384 1385 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1386 1387 // Optimized nmethod scanning support routines 1388 1389 // Is an oop scavengeable 1390 virtual bool is_scavengable(oop obj); 1391 1392 // Register the given nmethod with the G1 heap. 1393 virtual void register_nmethod(nmethod* nm); 1394 1395 // Unregister the given nmethod from the G1 heap. 1396 virtual void unregister_nmethod(nmethod* nm); 1397 1398 // Free up superfluous code root memory. 1399 void purge_code_root_memory(); 1400 1401 // Rebuild the strong code root lists for each region 1402 // after a full GC. 1403 void rebuild_strong_code_roots(); 1404 1405 // Partial cleaning used when class unloading is disabled. 1406 // Let the caller choose what structures to clean out: 1407 // - StringTable 1408 // - SymbolTable 1409 // - StringDeduplication structures 1410 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1411 1412 // Complete cleaning used when class unloading is enabled. 1413 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1414 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1415 1416 // Redirty logged cards in the refinement queue. 1417 void redirty_logged_cards(); 1418 // Verification 1419 1420 // Perform any cleanup actions necessary before allowing a verification. 1421 virtual void prepare_for_verify(); 1422 1423 // Perform verification. 1424 1425 // vo == UsePrevMarking -> use "prev" marking information, 1426 // vo == UseNextMarking -> use "next" marking information 1427 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1428 // 1429 // NOTE: Only the "prev" marking information is guaranteed to be 1430 // consistent most of the time, so most calls to this should use 1431 // vo == UsePrevMarking. 1432 // Currently, there is only one case where this is called with 1433 // vo == UseNextMarking, which is to verify the "next" marking 1434 // information at the end of remark. 1435 // Currently there is only one place where this is called with 1436 // vo == UseFullMarking, which is to verify the marking during a 1437 // full GC. 1438 void verify(VerifyOption vo); 1439 1440 // WhiteBox testing support. 1441 virtual bool supports_concurrent_phase_control() const; 1442 virtual const char* const* concurrent_phases() const; 1443 virtual bool request_concurrent_phase(const char* phase); 1444 1445 // The methods below are here for convenience and dispatch the 1446 // appropriate method depending on value of the given VerifyOption 1447 // parameter. The values for that parameter, and their meanings, 1448 // are the same as those above. 1449 1450 bool is_obj_dead_cond(const oop obj, 1451 const HeapRegion* hr, 1452 const VerifyOption vo) const; 1453 1454 bool is_obj_dead_cond(const oop obj, 1455 const VerifyOption vo) const; 1456 1457 G1HeapSummary create_g1_heap_summary(); 1458 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1459 1460 // Printing 1461 private: 1462 void print_heap_regions() const; 1463 void print_regions_on(outputStream* st) const; 1464 1465 public: 1466 virtual void print_on(outputStream* st) const; 1467 virtual void print_extended_on(outputStream* st) const; 1468 virtual void print_on_error(outputStream* st) const; 1469 1470 virtual void print_gc_threads_on(outputStream* st) const; 1471 virtual void gc_threads_do(ThreadClosure* tc) const; 1472 1473 // Override 1474 void print_tracing_info() const; 1475 1476 // The following two methods are helpful for debugging RSet issues. 1477 void print_cset_rsets() PRODUCT_RETURN; 1478 void print_all_rsets() PRODUCT_RETURN; 1479 1480 public: 1481 size_t pending_card_num(); 1482 1483 protected: 1484 size_t _max_heap_capacity; 1485 }; 1486 1487 class G1ParEvacuateFollowersClosure : public VoidClosure { 1488 private: 1489 double _start_term; 1490 double _term_time; 1491 size_t _term_attempts; 1492 1493 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1494 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1495 protected: 1496 G1CollectedHeap* _g1h; 1497 G1ParScanThreadState* _par_scan_state; 1498 RefToScanQueueSet* _queues; 1499 ParallelTaskTerminator* _terminator; 1500 1501 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1502 RefToScanQueueSet* queues() { return _queues; } 1503 ParallelTaskTerminator* terminator() { return _terminator; } 1504 1505 public: 1506 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1507 G1ParScanThreadState* par_scan_state, 1508 RefToScanQueueSet* queues, 1509 ParallelTaskTerminator* terminator) 1510 : _g1h(g1h), _par_scan_state(par_scan_state), 1511 _queues(queues), _terminator(terminator), 1512 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1513 1514 void do_void(); 1515 1516 double term_time() const { return _term_time; } 1517 size_t term_attempts() const { return _term_attempts; } 1518 1519 private: 1520 inline bool offer_termination(); 1521 }; 1522 1523 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP