1 /* 2 * Copyright (c) 2001, 2017, 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 "memory/memRegion.hpp" 53 #include "services/memoryManager.hpp" 54 #include "utilities/stack.hpp" 55 56 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 57 // It uses the "Garbage First" heap organization and algorithm, which 58 // may combine concurrent marking with parallel, incremental compaction of 59 // heap subsets that will yield large amounts of garbage. 60 61 // Forward declarations 62 class HeapRegion; 63 class HRRSCleanupTask; 64 class GenerationSpec; 65 class G1ParScanThreadState; 66 class G1ParScanThreadStateSet; 67 class G1ParScanThreadState; 68 class MemoryPool; 69 class ObjectClosure; 70 class SpaceClosure; 71 class CompactibleSpaceClosure; 72 class Space; 73 class G1CollectionSet; 74 class G1CollectorPolicy; 75 class G1Policy; 76 class G1HotCardCache; 77 class G1RemSet; 78 class G1YoungRemSetSamplingThread; 79 class HeapRegionRemSetIterator; 80 class G1ConcurrentMark; 81 class ConcurrentMarkThread; 82 class G1ConcurrentRefine; 83 class GenerationCounters; 84 class STWGCTimer; 85 class G1NewTracer; 86 class EvacuationFailedInfo; 87 class nmethod; 88 class Ticks; 89 class WorkGang; 90 class G1Allocator; 91 class G1ArchiveAllocator; 92 class G1FullGCScope; 93 class G1HeapVerifier; 94 class G1HeapSizingPolicy; 95 class G1HeapSummary; 96 class G1EvacSummary; 97 98 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 99 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 100 101 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 102 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 103 104 // The G1 STW is alive closure. 105 // An instance is embedded into the G1CH and used as the 106 // (optional) _is_alive_non_header closure in the STW 107 // reference processor. It is also extensively used during 108 // reference processing during STW evacuation pauses. 109 class G1STWIsAliveClosure: public BoolObjectClosure { 110 G1CollectedHeap* _g1; 111 public: 112 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 113 bool do_object_b(oop p); 114 }; 115 116 class G1RegionMappingChangedListener : public G1MappingChangedListener { 117 private: 118 void reset_from_card_cache(uint start_idx, size_t num_regions); 119 public: 120 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 121 }; 122 123 class G1CollectedHeap : public CollectedHeap { 124 friend class G1FreeCollectionSetTask; 125 friend class VM_CollectForMetadataAllocation; 126 friend class VM_G1CollectForAllocation; 127 friend class VM_G1CollectFull; 128 friend class VM_G1IncCollectionPause; 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 GCMemoryManager _memory_manager; 155 GCMemoryManager _full_gc_memory_manager; 156 157 MemoryPool* _eden_pool; 158 MemoryPool* _survivor_pool; 159 MemoryPool* _old_pool; 160 161 static size_t _humongous_object_threshold_in_words; 162 163 // The secondary free list which contains regions that have been 164 // freed up during the cleanup process. This will be appended to 165 // the master free list when appropriate. 166 FreeRegionList _secondary_free_list; 167 168 // It keeps track of the old regions. 169 HeapRegionSet _old_set; 170 171 // It keeps track of the humongous regions. 172 HeapRegionSet _humongous_set; 173 174 virtual void initialize_serviceability(); 175 176 void eagerly_reclaim_humongous_regions(); 177 // Start a new incremental collection set for the next pause. 178 void start_new_collection_set(); 179 180 // The number of regions we could create by expansion. 181 uint _expansion_regions; 182 183 // The block offset table for the G1 heap. 184 G1BlockOffsetTable* _bot; 185 186 // Tears down the region sets / lists so that they are empty and the 187 // regions on the heap do not belong to a region set / list. The 188 // only exception is the humongous set which we leave unaltered. If 189 // free_list_only is true, it will only tear down the master free 190 // list. It is called before a Full GC (free_list_only == false) or 191 // before heap shrinking (free_list_only == true). 192 void tear_down_region_sets(bool free_list_only); 193 194 // Rebuilds the region sets / lists so that they are repopulated to 195 // reflect the contents of the heap. The only exception is the 196 // humongous set which was not torn down in the first place. If 197 // free_list_only is true, it will only rebuild the master free 198 // list. It is called after a Full GC (free_list_only == false) or 199 // after heap shrinking (free_list_only == true). 200 void rebuild_region_sets(bool free_list_only); 201 202 // Callback for region mapping changed events. 203 G1RegionMappingChangedListener _listener; 204 205 // The sequence of all heap regions in the heap. 206 HeapRegionManager _hrm; 207 208 // Manages all allocations with regions except humongous object allocations. 209 G1Allocator* _allocator; 210 211 // Manages all heap verification. 212 G1HeapVerifier* _verifier; 213 214 // Outside of GC pauses, the number of bytes used in all regions other 215 // than the current allocation region(s). 216 size_t _summary_bytes_used; 217 218 void increase_used(size_t bytes); 219 void decrease_used(size_t bytes); 220 221 void set_used(size_t bytes); 222 223 // Class that handles archive allocation ranges. 224 G1ArchiveAllocator* _archive_allocator; 225 226 // Statistics for each allocation context 227 AllocationContextStats _allocation_context_stats; 228 229 // GC allocation statistics policy for survivors. 230 G1EvacStats _survivor_evac_stats; 231 232 // GC allocation statistics policy for tenured objects. 233 G1EvacStats _old_evac_stats; 234 235 // It specifies whether we should attempt to expand the heap after a 236 // region allocation failure. If heap expansion fails we set this to 237 // false so that we don't re-attempt the heap expansion (it's likely 238 // that subsequent expansion attempts will also fail if one fails). 239 // Currently, it is only consulted during GC and it's reset at the 240 // start of each GC. 241 bool _expand_heap_after_alloc_failure; 242 243 // Helper for monitoring and management support. 244 G1MonitoringSupport* _g1mm; 245 246 // Records whether the region at the given index is (still) a 247 // candidate for eager reclaim. Only valid for humongous start 248 // regions; other regions have unspecified values. Humongous start 249 // regions are initialized at start of collection pause, with 250 // candidates removed from the set as they are found reachable from 251 // roots or the young generation. 252 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 253 protected: 254 bool default_value() const { return false; } 255 public: 256 void clear() { G1BiasedMappedArray<bool>::clear(); } 257 void set_candidate(uint region, bool value) { 258 set_by_index(region, value); 259 } 260 bool is_candidate(uint region) { 261 return get_by_index(region); 262 } 263 }; 264 265 HumongousReclaimCandidates _humongous_reclaim_candidates; 266 // Stores whether during humongous object registration we found candidate regions. 267 // If not, we can skip a few steps. 268 bool _has_humongous_reclaim_candidates; 269 270 volatile uint _gc_time_stamp; 271 272 G1HRPrinter _hr_printer; 273 274 // It decides whether an explicit GC should start a concurrent cycle 275 // instead of doing a STW GC. Currently, a concurrent cycle is 276 // explicitly started if: 277 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 278 // (b) cause == _g1_humongous_allocation 279 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 280 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 281 // (e) cause == _update_allocation_context_stats_inc 282 // (f) 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 // The following three methods take a gc_count_before_ret 458 // parameter which is used to return the GC count if the method 459 // returns NULL. Given that we are required to read the GC count 460 // while holding the Heap_lock, and these paths will take the 461 // Heap_lock at some point, it's easier to get them to read the GC 462 // count while holding the Heap_lock before they return NULL instead 463 // of the caller (namely: mem_allocate()) having to also take the 464 // Heap_lock just to read the GC count. 465 466 // First-level mutator allocation attempt: try to allocate out of 467 // the mutator alloc region without taking the Heap_lock. This 468 // should only be used for non-humongous allocations. 469 inline HeapWord* attempt_allocation(size_t word_size, 470 uint* gc_count_before_ret, 471 uint* gclocker_retry_count_ret); 472 473 // Second-level mutator allocation attempt: take the Heap_lock and 474 // retry the allocation attempt, potentially scheduling a GC 475 // pause. This should only be used for non-humongous allocations. 476 HeapWord* attempt_allocation_slow(size_t word_size, 477 AllocationContext_t context, 478 uint* gc_count_before_ret, 479 uint* gclocker_retry_count_ret); 480 481 // Takes the Heap_lock and attempts a humongous allocation. It can 482 // potentially schedule a GC pause. 483 HeapWord* attempt_allocation_humongous(size_t word_size, 484 uint* gc_count_before_ret, 485 uint* gclocker_retry_count_ret); 486 487 // Allocation attempt that should be called during safepoints (e.g., 488 // at the end of a successful GC). expect_null_mutator_alloc_region 489 // specifies whether the mutator alloc region is expected to be NULL 490 // or not. 491 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 492 AllocationContext_t context, 493 bool expect_null_mutator_alloc_region); 494 495 // These methods are the "callbacks" from the G1AllocRegion class. 496 497 // For mutator alloc regions. 498 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 499 void retire_mutator_alloc_region(HeapRegion* alloc_region, 500 size_t allocated_bytes); 501 502 // For GC alloc regions. 503 bool has_more_regions(InCSetState dest); 504 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 505 void retire_gc_alloc_region(HeapRegion* alloc_region, 506 size_t allocated_bytes, InCSetState dest); 507 508 // - if explicit_gc is true, the GC is for a System.gc() etc, 509 // otherwise it's for a failed allocation. 510 // - if clear_all_soft_refs is true, all soft references should be 511 // cleared during the GC. 512 // - it returns false if it is unable to do the collection due to the 513 // GC locker being active, true otherwise. 514 bool do_full_collection(bool explicit_gc, 515 bool clear_all_soft_refs); 516 517 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 518 virtual void do_full_collection(bool clear_all_soft_refs); 519 520 // Resize the heap if necessary after a full collection. 521 void resize_if_necessary_after_full_collection(); 522 523 // Callback from VM_G1CollectForAllocation operation. 524 // This function does everything necessary/possible to satisfy a 525 // failed allocation request (including collection, expansion, etc.) 526 HeapWord* satisfy_failed_allocation(size_t word_size, 527 AllocationContext_t context, 528 bool* succeeded); 529 private: 530 // Internal helpers used during full GC to split it up to 531 // increase readability. 532 void abort_concurrent_cycle(); 533 void verify_before_full_collection(bool explicit_gc); 534 void prepare_heap_for_full_collection(); 535 void prepare_heap_for_mutators(); 536 void abort_refinement(); 537 void verify_after_full_collection(); 538 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 539 540 // Helper method for satisfy_failed_allocation() 541 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 542 AllocationContext_t context, 543 bool do_gc, 544 bool clear_all_soft_refs, 545 bool expect_null_mutator_alloc_region, 546 bool* gc_succeeded); 547 548 protected: 549 // Attempting to expand the heap sufficiently 550 // to support an allocation of the given "word_size". If 551 // successful, perform the allocation and return the address of the 552 // allocated block, or else "NULL". 553 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 554 555 // Preserve any referents discovered by concurrent marking that have not yet been 556 // copied by the STW pause. 557 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 558 // Process any reference objects discovered during 559 // an incremental evacuation pause. 560 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 561 562 // Enqueue any remaining discovered references 563 // after processing. 564 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 565 566 // Merges the information gathered on a per-thread basis for all worker threads 567 // during GC into global variables. 568 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 569 public: 570 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 571 572 WorkGang* workers() const { return _workers; } 573 574 G1Allocator* allocator() { 575 return _allocator; 576 } 577 578 G1HeapVerifier* verifier() { 579 return _verifier; 580 } 581 582 G1MonitoringSupport* g1mm() { 583 assert(_g1mm != NULL, "should have been initialized"); 584 return _g1mm; 585 } 586 587 // Expand the garbage-first heap by at least the given size (in bytes!). 588 // Returns true if the heap was expanded by the requested amount; 589 // false otherwise. 590 // (Rounds up to a HeapRegion boundary.) 591 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 592 593 // Returns the PLAB statistics for a given destination. 594 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 595 596 // Determines PLAB size for a given destination. 597 inline size_t desired_plab_sz(InCSetState dest); 598 599 inline AllocationContextStats& allocation_context_stats(); 600 601 // Do anything common to GC's. 602 void gc_prologue(bool full); 603 void gc_epilogue(bool full); 604 605 // Modify the reclaim candidate set and test for presence. 606 // These are only valid for starts_humongous regions. 607 inline void set_humongous_reclaim_candidate(uint region, bool value); 608 inline bool is_humongous_reclaim_candidate(uint region); 609 610 // Remove from the reclaim candidate set. Also remove from the 611 // collection set so that later encounters avoid the slow path. 612 inline void set_humongous_is_live(oop obj); 613 614 // Register the given region to be part of the collection set. 615 inline void register_humongous_region_with_cset(uint index); 616 // Register regions with humongous objects (actually on the start region) in 617 // the in_cset_fast_test table. 618 void register_humongous_regions_with_cset(); 619 // We register a region with the fast "in collection set" test. We 620 // simply set to true the array slot corresponding to this region. 621 void register_young_region_with_cset(HeapRegion* r) { 622 _in_cset_fast_test.set_in_young(r->hrm_index()); 623 } 624 void register_old_region_with_cset(HeapRegion* r) { 625 _in_cset_fast_test.set_in_old(r->hrm_index()); 626 } 627 inline void register_ext_region_with_cset(HeapRegion* r) { 628 _in_cset_fast_test.set_ext(r->hrm_index()); 629 } 630 void clear_in_cset(const HeapRegion* hr) { 631 _in_cset_fast_test.clear(hr); 632 } 633 634 void clear_cset_fast_test() { 635 _in_cset_fast_test.clear(); 636 } 637 638 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 639 640 // This is called at the start of either a concurrent cycle or a Full 641 // GC to update the number of old marking cycles started. 642 void increment_old_marking_cycles_started(); 643 644 // This is called at the end of either a concurrent cycle or a Full 645 // GC to update the number of old marking cycles completed. Those two 646 // can happen in a nested fashion, i.e., we start a concurrent 647 // cycle, a Full GC happens half-way through it which ends first, 648 // and then the cycle notices that a Full GC happened and ends 649 // too. The concurrent parameter is a boolean to help us do a bit 650 // tighter consistency checking in the method. If concurrent is 651 // false, the caller is the inner caller in the nesting (i.e., the 652 // Full GC). If concurrent is true, the caller is the outer caller 653 // in this nesting (i.e., the concurrent cycle). Further nesting is 654 // not currently supported. The end of this call also notifies 655 // the FullGCCount_lock in case a Java thread is waiting for a full 656 // GC to happen (e.g., it called System.gc() with 657 // +ExplicitGCInvokesConcurrent). 658 void increment_old_marking_cycles_completed(bool concurrent); 659 660 uint old_marking_cycles_completed() { 661 return _old_marking_cycles_completed; 662 } 663 664 G1HRPrinter* hr_printer() { return &_hr_printer; } 665 666 // Allocates a new heap region instance. 667 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 668 669 // Allocate the highest free region in the reserved heap. This will commit 670 // regions as necessary. 671 HeapRegion* alloc_highest_free_region(); 672 673 // Frees a non-humongous region by initializing its contents and 674 // adding it to the free list that's passed as a parameter (this is 675 // usually a local list which will be appended to the master free 676 // list later). The used bytes of freed regions are accumulated in 677 // pre_used. If skip_remset is true, the region's RSet will not be freed 678 // up. If skip_hot_card_cache is true, the region's hot card cache will not 679 // be freed up. The assumption is that this will be done later. 680 // The locked parameter indicates if the caller has already taken 681 // care of proper synchronization. This may allow some optimizations. 682 void free_region(HeapRegion* hr, 683 FreeRegionList* free_list, 684 bool skip_remset, 685 bool skip_hot_card_cache = false, 686 bool locked = false); 687 688 // It dirties the cards that cover the block so that the post 689 // write barrier never queues anything when updating objects on this 690 // block. It is assumed (and in fact we assert) that the block 691 // belongs to a young region. 692 inline void dirty_young_block(HeapWord* start, size_t word_size); 693 694 // Frees a humongous region by collapsing it into individual regions 695 // and calling free_region() for each of them. The freed regions 696 // will be added to the free list that's passed as a parameter (this 697 // is usually a local list which will be appended to the master free 698 // list later). The used bytes of freed regions are accumulated in 699 // pre_used. If skip_remset is true, the region's RSet will not be freed 700 // up. The assumption is that this will be done later. 701 void free_humongous_region(HeapRegion* hr, 702 FreeRegionList* free_list, 703 bool skip_remset); 704 705 // Facility for allocating in 'archive' regions in high heap memory and 706 // recording the allocated ranges. These should all be called from the 707 // VM thread at safepoints, without the heap lock held. They can be used 708 // to create and archive a set of heap regions which can be mapped at the 709 // same fixed addresses in a subsequent JVM invocation. 710 void begin_archive_alloc_range(bool open = false); 711 712 // Check if the requested size would be too large for an archive allocation. 713 bool is_archive_alloc_too_large(size_t word_size); 714 715 // Allocate memory of the requested size from the archive region. This will 716 // return NULL if the size is too large or if no memory is available. It 717 // does not trigger a garbage collection. 718 HeapWord* archive_mem_allocate(size_t word_size); 719 720 // Optionally aligns the end address and returns the allocated ranges in 721 // an array of MemRegions in order of ascending addresses. 722 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 723 size_t end_alignment_in_bytes = 0); 724 725 // Facility for allocating a fixed range within the heap and marking 726 // the containing regions as 'archive'. For use at JVM init time, when the 727 // caller may mmap archived heap data at the specified range(s). 728 // Verify that the MemRegions specified in the argument array are within the 729 // reserved heap. 730 bool check_archive_addresses(MemRegion* range, size_t count); 731 732 // Commit the appropriate G1 regions containing the specified MemRegions 733 // and mark them as 'archive' regions. The regions in the array must be 734 // non-overlapping and in order of ascending address. 735 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 736 737 // Insert any required filler objects in the G1 regions around the specified 738 // ranges to make the regions parseable. This must be called after 739 // alloc_archive_regions, and after class loading has occurred. 740 void fill_archive_regions(MemRegion* range, size_t count); 741 742 // For each of the specified MemRegions, uncommit the containing G1 regions 743 // which had been allocated by alloc_archive_regions. This should be called 744 // rather than fill_archive_regions at JVM init time if the archive file 745 // mapping failed, with the same non-overlapping and sorted MemRegion array. 746 void dealloc_archive_regions(MemRegion* range, size_t count); 747 748 protected: 749 750 // Shrink the garbage-first heap by at most the given size (in bytes!). 751 // (Rounds down to a HeapRegion boundary.) 752 virtual void shrink(size_t expand_bytes); 753 void shrink_helper(size_t expand_bytes); 754 755 #if TASKQUEUE_STATS 756 static void print_taskqueue_stats_hdr(outputStream* const st); 757 void print_taskqueue_stats() const; 758 void reset_taskqueue_stats(); 759 #endif // TASKQUEUE_STATS 760 761 // Schedule the VM operation that will do an evacuation pause to 762 // satisfy an allocation request of word_size. *succeeded will 763 // return whether the VM operation was successful (it did do an 764 // evacuation pause) or not (another thread beat us to it or the GC 765 // locker was active). Given that we should not be holding the 766 // Heap_lock when we enter this method, we will pass the 767 // gc_count_before (i.e., total_collections()) as a parameter since 768 // it has to be read while holding the Heap_lock. Currently, both 769 // methods that call do_collection_pause() release the Heap_lock 770 // before the call, so it's easy to read gc_count_before just before. 771 HeapWord* do_collection_pause(size_t word_size, 772 uint gc_count_before, 773 bool* succeeded, 774 GCCause::Cause gc_cause); 775 776 void wait_for_root_region_scanning(); 777 778 // The guts of the incremental collection pause, executed by the vm 779 // thread. It returns false if it is unable to do the collection due 780 // to the GC locker being active, true otherwise 781 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 782 783 // Actually do the work of evacuating the collection set. 784 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 785 786 void pre_evacuate_collection_set(); 787 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 788 789 // Print the header for the per-thread termination statistics. 790 static void print_termination_stats_hdr(); 791 // Print actual per-thread termination statistics. 792 void print_termination_stats(uint worker_id, 793 double elapsed_ms, 794 double strong_roots_ms, 795 double term_ms, 796 size_t term_attempts, 797 size_t alloc_buffer_waste, 798 size_t undo_waste) const; 799 // Update object copying statistics. 800 void record_obj_copy_mem_stats(); 801 802 // The hot card cache for remembered set insertion optimization. 803 G1HotCardCache* _hot_card_cache; 804 805 // The g1 remembered set of the heap. 806 G1RemSet* _g1_rem_set; 807 808 // A set of cards that cover the objects for which the Rsets should be updated 809 // concurrently after the collection. 810 DirtyCardQueueSet _dirty_card_queue_set; 811 812 // After a collection pause, convert the regions in the collection set into free 813 // regions. 814 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 815 816 // Abandon the current collection set without recording policy 817 // statistics or updating free lists. 818 void abandon_collection_set(G1CollectionSet* collection_set); 819 820 // The concurrent marker (and the thread it runs in.) 821 G1ConcurrentMark* _cm; 822 ConcurrentMarkThread* _cmThread; 823 824 // The concurrent refiner. 825 G1ConcurrentRefine* _cr; 826 827 // The parallel task queues 828 RefToScanQueueSet *_task_queues; 829 830 // True iff a evacuation has failed in the current collection. 831 bool _evacuation_failed; 832 833 EvacuationFailedInfo* _evacuation_failed_info_array; 834 835 // Failed evacuations cause some logical from-space objects to have 836 // forwarding pointers to themselves. Reset them. 837 void remove_self_forwarding_pointers(); 838 839 // Restore the objects in the regions in the collection set after an 840 // evacuation failure. 841 void restore_after_evac_failure(); 842 843 PreservedMarksSet _preserved_marks_set; 844 845 // Preserve the mark of "obj", if necessary, in preparation for its mark 846 // word being overwritten with a self-forwarding-pointer. 847 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 848 849 #ifndef PRODUCT 850 // Support for forcing evacuation failures. Analogous to 851 // PromotionFailureALot for the other collectors. 852 853 // Records whether G1EvacuationFailureALot should be in effect 854 // for the current GC 855 bool _evacuation_failure_alot_for_current_gc; 856 857 // Used to record the GC number for interval checking when 858 // determining whether G1EvaucationFailureALot is in effect 859 // for the current GC. 860 size_t _evacuation_failure_alot_gc_number; 861 862 // Count of the number of evacuations between failures. 863 volatile size_t _evacuation_failure_alot_count; 864 865 // Set whether G1EvacuationFailureALot should be in effect 866 // for the current GC (based upon the type of GC and which 867 // command line flags are set); 868 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 869 bool during_initial_mark, 870 bool during_marking); 871 872 inline void set_evacuation_failure_alot_for_current_gc(); 873 874 // Return true if it's time to cause an evacuation failure. 875 inline bool evacuation_should_fail(); 876 877 // Reset the G1EvacuationFailureALot counters. Should be called at 878 // the end of an evacuation pause in which an evacuation failure occurred. 879 inline void reset_evacuation_should_fail(); 880 #endif // !PRODUCT 881 882 // ("Weak") Reference processing support. 883 // 884 // G1 has 2 instances of the reference processor class. One 885 // (_ref_processor_cm) handles reference object discovery 886 // and subsequent processing during concurrent marking cycles. 887 // 888 // The other (_ref_processor_stw) handles reference object 889 // discovery and processing during full GCs and incremental 890 // evacuation pauses. 891 // 892 // During an incremental pause, reference discovery will be 893 // temporarily disabled for _ref_processor_cm and will be 894 // enabled for _ref_processor_stw. At the end of the evacuation 895 // pause references discovered by _ref_processor_stw will be 896 // processed and discovery will be disabled. The previous 897 // setting for reference object discovery for _ref_processor_cm 898 // will be re-instated. 899 // 900 // At the start of marking: 901 // * Discovery by the CM ref processor is verified to be inactive 902 // and it's discovered lists are empty. 903 // * Discovery by the CM ref processor is then enabled. 904 // 905 // At the end of marking: 906 // * Any references on the CM ref processor's discovered 907 // lists are processed (possibly MT). 908 // 909 // At the start of full GC we: 910 // * Disable discovery by the CM ref processor and 911 // empty CM ref processor's discovered lists 912 // (without processing any entries). 913 // * Verify that the STW ref processor is inactive and it's 914 // discovered lists are empty. 915 // * Temporarily set STW ref processor discovery as single threaded. 916 // * Temporarily clear the STW ref processor's _is_alive_non_header 917 // field. 918 // * Finally enable discovery by the STW ref processor. 919 // 920 // The STW ref processor is used to record any discovered 921 // references during the full GC. 922 // 923 // At the end of a full GC we: 924 // * Enqueue any reference objects discovered by the STW ref processor 925 // that have non-live referents. This has the side-effect of 926 // making the STW ref processor inactive by disabling discovery. 927 // * Verify that the CM ref processor is still inactive 928 // and no references have been placed on it's discovered 929 // lists (also checked as a precondition during initial marking). 930 931 // The (stw) reference processor... 932 ReferenceProcessor* _ref_processor_stw; 933 934 // During reference object discovery, the _is_alive_non_header 935 // closure (if non-null) is applied to the referent object to 936 // determine whether the referent is live. If so then the 937 // reference object does not need to be 'discovered' and can 938 // be treated as a regular oop. This has the benefit of reducing 939 // the number of 'discovered' reference objects that need to 940 // be processed. 941 // 942 // Instance of the is_alive closure for embedding into the 943 // STW reference processor as the _is_alive_non_header field. 944 // Supplying a value for the _is_alive_non_header field is 945 // optional but doing so prevents unnecessary additions to 946 // the discovered lists during reference discovery. 947 G1STWIsAliveClosure _is_alive_closure_stw; 948 949 // The (concurrent marking) reference processor... 950 ReferenceProcessor* _ref_processor_cm; 951 952 // Instance of the concurrent mark is_alive closure for embedding 953 // into the Concurrent Marking reference processor as the 954 // _is_alive_non_header field. Supplying a value for the 955 // _is_alive_non_header field is optional but doing so prevents 956 // unnecessary additions to the discovered lists during reference 957 // discovery. 958 G1CMIsAliveClosure _is_alive_closure_cm; 959 960 volatile bool _free_regions_coming; 961 962 public: 963 964 RefToScanQueue *task_queue(uint i) const; 965 966 uint num_task_queues() const; 967 968 // A set of cards where updates happened during the GC 969 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 970 971 // Create a G1CollectedHeap with the specified policy. 972 // Must call the initialize method afterwards. 973 // May not return if something goes wrong. 974 G1CollectedHeap(G1CollectorPolicy* policy); 975 976 private: 977 jint initialize_concurrent_refinement(); 978 jint initialize_young_gen_sampling_thread(); 979 public: 980 // Initialize the G1CollectedHeap to have the initial and 981 // maximum sizes and remembered and barrier sets 982 // specified by the policy object. 983 jint initialize(); 984 985 virtual void stop(); 986 virtual void safepoint_synchronize_begin(); 987 virtual void safepoint_synchronize_end(); 988 989 // Return the (conservative) maximum heap alignment for any G1 heap 990 static size_t conservative_max_heap_alignment(); 991 992 // Does operations required after initialization has been done. 993 void post_initialize(); 994 995 // Initialize weak reference processing. 996 void ref_processing_init(); 997 998 virtual Name kind() const { 999 return CollectedHeap::G1CollectedHeap; 1000 } 1001 1002 virtual const char* name() const { 1003 return "G1"; 1004 } 1005 1006 const G1CollectorState* collector_state() const { return &_collector_state; } 1007 G1CollectorState* collector_state() { return &_collector_state; } 1008 1009 // The current policy object for the collector. 1010 G1Policy* g1_policy() const { return _g1_policy; } 1011 1012 const G1CollectionSet* collection_set() const { return &_collection_set; } 1013 G1CollectionSet* collection_set() { return &_collection_set; } 1014 1015 virtual CollectorPolicy* collector_policy() const; 1016 1017 // Adaptive size policy. No such thing for g1. 1018 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1019 1020 virtual GrowableArray<GCMemoryManager*> memory_managers(); 1021 virtual GrowableArray<MemoryPool*> memory_pools(); 1022 1023 // The rem set and barrier set. 1024 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1025 1026 // Try to minimize the remembered set. 1027 void scrub_rem_set(); 1028 1029 uint get_gc_time_stamp() { 1030 return _gc_time_stamp; 1031 } 1032 1033 inline void reset_gc_time_stamp(); 1034 1035 void check_gc_time_stamps() PRODUCT_RETURN; 1036 1037 inline void increment_gc_time_stamp(); 1038 1039 // Reset the given region's GC timestamp. If it's starts humongous, 1040 // also reset the GC timestamp of its corresponding 1041 // continues humongous regions too. 1042 void reset_gc_time_stamps(HeapRegion* hr); 1043 1044 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1045 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1046 1047 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1048 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1049 1050 // The shared block offset table array. 1051 G1BlockOffsetTable* bot() const { return _bot; } 1052 1053 // Reference Processing accessors 1054 1055 // The STW reference processor.... 1056 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1057 1058 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1059 1060 // The Concurrent Marking reference processor... 1061 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1062 1063 size_t unused_committed_regions_in_bytes() const; 1064 virtual size_t capacity() const; 1065 virtual size_t used() const; 1066 // This should be called when we're not holding the heap lock. The 1067 // result might be a bit inaccurate. 1068 size_t used_unlocked() const; 1069 size_t recalculate_used() const; 1070 1071 // These virtual functions do the actual allocation. 1072 // Some heaps may offer a contiguous region for shared non-blocking 1073 // allocation, via inlined code (by exporting the address of the top and 1074 // end fields defining the extent of the contiguous allocation region.) 1075 // But G1CollectedHeap doesn't yet support this. 1076 1077 virtual bool is_maximal_no_gc() const { 1078 return _hrm.available() == 0; 1079 } 1080 1081 // The current number of regions in the heap. 1082 uint num_regions() const { return _hrm.length(); } 1083 1084 // The max number of regions in the heap. 1085 uint max_regions() const { return _hrm.max_length(); } 1086 1087 // The number of regions that are completely free. 1088 uint num_free_regions() const { return _hrm.num_free_regions(); } 1089 1090 MemoryUsage get_auxiliary_data_memory_usage() const { 1091 return _hrm.get_auxiliary_data_memory_usage(); 1092 } 1093 1094 // The number of regions that are not completely free. 1095 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1096 1097 #ifdef ASSERT 1098 bool is_on_master_free_list(HeapRegion* hr) { 1099 return _hrm.is_free(hr); 1100 } 1101 #endif // ASSERT 1102 1103 // Wrapper for the region list operations that can be called from 1104 // methods outside this class. 1105 1106 void secondary_free_list_add(FreeRegionList* list) { 1107 _secondary_free_list.add_ordered(list); 1108 } 1109 1110 void append_secondary_free_list() { 1111 _hrm.insert_list_into_free_list(&_secondary_free_list); 1112 } 1113 1114 void append_secondary_free_list_if_not_empty_with_lock() { 1115 // If the secondary free list looks empty there's no reason to 1116 // take the lock and then try to append it. 1117 if (!_secondary_free_list.is_empty()) { 1118 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1119 append_secondary_free_list(); 1120 } 1121 } 1122 1123 inline void old_set_add(HeapRegion* hr); 1124 inline void old_set_remove(HeapRegion* hr); 1125 1126 size_t non_young_capacity_bytes() { 1127 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1128 } 1129 1130 void set_free_regions_coming(); 1131 void reset_free_regions_coming(); 1132 bool free_regions_coming() { return _free_regions_coming; } 1133 void wait_while_free_regions_coming(); 1134 1135 // Determine whether the given region is one that we are using as an 1136 // old GC alloc region. 1137 bool is_old_gc_alloc_region(HeapRegion* hr); 1138 1139 // Perform a collection of the heap; intended for use in implementing 1140 // "System.gc". This probably implies as full a collection as the 1141 // "CollectedHeap" supports. 1142 virtual void collect(GCCause::Cause cause); 1143 1144 virtual bool copy_allocation_context_stats(const jint* contexts, 1145 jlong* totals, 1146 jbyte* accuracy, 1147 jint len); 1148 1149 // True iff an evacuation has failed in the most-recent collection. 1150 bool evacuation_failed() { return _evacuation_failed; } 1151 1152 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1153 void prepend_to_freelist(FreeRegionList* list); 1154 void decrement_summary_bytes(size_t bytes); 1155 1156 virtual bool is_in(const void* p) const; 1157 #ifdef ASSERT 1158 // Returns whether p is in one of the available areas of the heap. Slow but 1159 // extensive version. 1160 bool is_in_exact(const void* p) const; 1161 #endif 1162 1163 // Return "TRUE" iff the given object address is within the collection 1164 // set. Assumes that the reference points into the heap. 1165 inline bool is_in_cset(const HeapRegion *hr); 1166 inline bool is_in_cset(oop obj); 1167 inline bool is_in_cset(HeapWord* addr); 1168 1169 inline bool is_in_cset_or_humongous(const oop obj); 1170 1171 private: 1172 // This array is used for a quick test on whether a reference points into 1173 // the collection set or not. Each of the array's elements denotes whether the 1174 // corresponding region is in the collection set or not. 1175 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1176 1177 public: 1178 1179 inline InCSetState in_cset_state(const oop obj); 1180 1181 // Return "TRUE" iff the given object address is in the reserved 1182 // region of g1. 1183 bool is_in_g1_reserved(const void* p) const { 1184 return _hrm.reserved().contains(p); 1185 } 1186 1187 // Returns a MemRegion that corresponds to the space that has been 1188 // reserved for the heap 1189 MemRegion g1_reserved() const { 1190 return _hrm.reserved(); 1191 } 1192 1193 virtual bool is_in_closed_subset(const void* p) const; 1194 1195 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1196 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1197 } 1198 1199 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1200 1201 // Iteration functions. 1202 1203 // Iterate over all objects, calling "cl.do_object" on each. 1204 virtual void object_iterate(ObjectClosure* cl); 1205 1206 virtual void safe_object_iterate(ObjectClosure* cl) { 1207 object_iterate(cl); 1208 } 1209 1210 // Iterate over heap regions, in address order, terminating the 1211 // iteration early if the "doHeapRegion" method returns "true". 1212 void heap_region_iterate(HeapRegionClosure* blk) const; 1213 1214 // Return the region with the given index. It assumes the index is valid. 1215 inline HeapRegion* region_at(uint index) const; 1216 1217 // Return the next region (by index) that is part of the same 1218 // humongous object that hr is part of. 1219 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1220 1221 // Calculate the region index of the given address. Given address must be 1222 // within the heap. 1223 inline uint addr_to_region(HeapWord* addr) const; 1224 1225 inline HeapWord* bottom_addr_for_region(uint index) const; 1226 1227 // Two functions to iterate over the heap regions in parallel. Threads 1228 // compete using the HeapRegionClaimer to claim the regions before 1229 // applying the closure on them. 1230 // The _from_worker_offset version uses the HeapRegionClaimer and 1231 // the worker id to calculate a start offset to prevent all workers to 1232 // start from the point. 1233 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1234 HeapRegionClaimer* hrclaimer, 1235 uint worker_id) const; 1236 1237 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1238 HeapRegionClaimer* hrclaimer) const; 1239 1240 // Iterate over the regions (if any) in the current collection set. 1241 void collection_set_iterate(HeapRegionClosure* blk); 1242 1243 // Iterate over the regions (if any) in the current collection set. Starts the 1244 // iteration over the entire collection set so that the start regions of a given 1245 // worker id over the set active_workers are evenly spread across the set of 1246 // collection set regions. 1247 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1248 1249 // Returns the HeapRegion that contains addr. addr must not be NULL. 1250 template <class T> 1251 inline HeapRegion* heap_region_containing(const T addr) const; 1252 1253 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1254 // each address in the (reserved) heap is a member of exactly 1255 // one block. The defining characteristic of a block is that it is 1256 // possible to find its size, and thus to progress forward to the next 1257 // block. (Blocks may be of different sizes.) Thus, blocks may 1258 // represent Java objects, or they might be free blocks in a 1259 // free-list-based heap (or subheap), as long as the two kinds are 1260 // distinguishable and the size of each is determinable. 1261 1262 // Returns the address of the start of the "block" that contains the 1263 // address "addr". We say "blocks" instead of "object" since some heaps 1264 // may not pack objects densely; a chunk may either be an object or a 1265 // non-object. 1266 virtual HeapWord* block_start(const void* addr) const; 1267 1268 // Requires "addr" to be the start of a chunk, and returns its size. 1269 // "addr + size" is required to be the start of a new chunk, or the end 1270 // of the active area of the heap. 1271 virtual size_t block_size(const HeapWord* addr) const; 1272 1273 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1274 // the block is an object. 1275 virtual bool block_is_obj(const HeapWord* addr) const; 1276 1277 // Section on thread-local allocation buffers (TLABs) 1278 // See CollectedHeap for semantics. 1279 1280 bool supports_tlab_allocation() const; 1281 size_t tlab_capacity(Thread* ignored) const; 1282 size_t tlab_used(Thread* ignored) const; 1283 size_t max_tlab_size() const; 1284 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1285 1286 // Can a compiler initialize a new object without store barriers? 1287 // This permission only extends from the creation of a new object 1288 // via a TLAB up to the first subsequent safepoint. If such permission 1289 // is granted for this heap type, the compiler promises to call 1290 // defer_store_barrier() below on any slow path allocation of 1291 // a new object for which such initializing store barriers will 1292 // have been elided. G1, like CMS, allows this, but should be 1293 // ready to provide a compensating write barrier as necessary 1294 // if that storage came out of a non-young region. The efficiency 1295 // of this implementation depends crucially on being able to 1296 // answer very efficiently in constant time whether a piece of 1297 // storage in the heap comes from a young region or not. 1298 // See ReduceInitialCardMarks. 1299 virtual bool can_elide_tlab_store_barriers() const { 1300 return true; 1301 } 1302 1303 virtual bool card_mark_must_follow_store() const { 1304 return true; 1305 } 1306 1307 inline bool is_in_young(const oop obj); 1308 1309 // We don't need barriers for initializing stores to objects 1310 // in the young gen: for the SATB pre-barrier, there is no 1311 // pre-value that needs to be remembered; for the remembered-set 1312 // update logging post-barrier, we don't maintain remembered set 1313 // information for young gen objects. 1314 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1315 1316 // Returns "true" iff the given word_size is "very large". 1317 static bool is_humongous(size_t word_size) { 1318 // Note this has to be strictly greater-than as the TLABs 1319 // are capped at the humongous threshold and we want to 1320 // ensure that we don't try to allocate a TLAB as 1321 // humongous and that we don't allocate a humongous 1322 // object in a TLAB. 1323 return word_size > _humongous_object_threshold_in_words; 1324 } 1325 1326 // Returns the humongous threshold for a specific region size 1327 static size_t humongous_threshold_for(size_t region_size) { 1328 return (region_size / 2); 1329 } 1330 1331 // Returns the number of regions the humongous object of the given word size 1332 // requires. 1333 static size_t humongous_obj_size_in_regions(size_t word_size); 1334 1335 // Print the maximum heap capacity. 1336 virtual size_t max_capacity() const; 1337 1338 virtual jlong millis_since_last_gc(); 1339 1340 1341 // Convenience function to be used in situations where the heap type can be 1342 // asserted to be this type. 1343 static G1CollectedHeap* heap(); 1344 1345 void set_region_short_lived_locked(HeapRegion* hr); 1346 // add appropriate methods for any other surv rate groups 1347 1348 const G1SurvivorRegions* survivor() const { return &_survivor; } 1349 1350 uint survivor_regions_count() const { 1351 return _survivor.length(); 1352 } 1353 1354 uint eden_regions_count() const { 1355 return _eden.length(); 1356 } 1357 1358 uint young_regions_count() const { 1359 return _eden.length() + _survivor.length(); 1360 } 1361 1362 uint old_regions_count() const { return _old_set.length(); } 1363 1364 uint humongous_regions_count() const { return _humongous_set.length(); } 1365 1366 #ifdef ASSERT 1367 bool check_young_list_empty(); 1368 #endif 1369 1370 // *** Stuff related to concurrent marking. It's not clear to me that so 1371 // many of these need to be public. 1372 1373 // The functions below are helper functions that a subclass of 1374 // "CollectedHeap" can use in the implementation of its virtual 1375 // functions. 1376 // This performs a concurrent marking of the live objects in a 1377 // bitmap off to the side. 1378 void doConcurrentMark(); 1379 1380 bool isMarkedNext(oop obj) const; 1381 1382 // Determine if an object is dead, given the object and also 1383 // the region to which the object belongs. An object is dead 1384 // iff a) it was not allocated since the last mark, b) it 1385 // is not marked, and c) it is not in an archive region. 1386 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1387 return 1388 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1389 !hr->is_archive(); 1390 } 1391 1392 // This function returns true when an object has been 1393 // around since the previous marking and hasn't yet 1394 // been marked during this marking, and is not in an archive region. 1395 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1396 return 1397 !hr->obj_allocated_since_next_marking(obj) && 1398 !isMarkedNext(obj) && 1399 !hr->is_archive(); 1400 } 1401 1402 // Determine if an object is dead, given only the object itself. 1403 // This will find the region to which the object belongs and 1404 // then call the region version of the same function. 1405 1406 // Added if it is NULL it isn't dead. 1407 1408 inline bool is_obj_dead(const oop obj) const; 1409 1410 inline bool is_obj_ill(const oop obj) const; 1411 1412 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1413 inline bool is_obj_dead_full(const oop obj) const; 1414 1415 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1416 1417 // Refinement 1418 1419 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1420 1421 // Optimized nmethod scanning support routines 1422 1423 // Is an oop scavengeable 1424 virtual bool is_scavengable(oop obj); 1425 1426 // Register the given nmethod with the G1 heap. 1427 virtual void register_nmethod(nmethod* nm); 1428 1429 // Unregister the given nmethod from the G1 heap. 1430 virtual void unregister_nmethod(nmethod* nm); 1431 1432 // Free up superfluous code root memory. 1433 void purge_code_root_memory(); 1434 1435 // Rebuild the strong code root lists for each region 1436 // after a full GC. 1437 void rebuild_strong_code_roots(); 1438 1439 // Partial cleaning used when class unloading is disabled. 1440 // Let the caller choose what structures to clean out: 1441 // - StringTable 1442 // - SymbolTable 1443 // - StringDeduplication structures 1444 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1445 1446 // Complete cleaning used when class unloading is enabled. 1447 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1448 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1449 1450 // Redirty logged cards in the refinement queue. 1451 void redirty_logged_cards(); 1452 // Verification 1453 1454 // Perform any cleanup actions necessary before allowing a verification. 1455 virtual void prepare_for_verify(); 1456 1457 // Perform verification. 1458 1459 // vo == UsePrevMarking -> use "prev" marking information, 1460 // vo == UseNextMarking -> use "next" marking information 1461 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1462 // 1463 // NOTE: Only the "prev" marking information is guaranteed to be 1464 // consistent most of the time, so most calls to this should use 1465 // vo == UsePrevMarking. 1466 // Currently, there is only one case where this is called with 1467 // vo == UseNextMarking, which is to verify the "next" marking 1468 // information at the end of remark. 1469 // Currently there is only one place where this is called with 1470 // vo == UseFullMarking, which is to verify the marking during a 1471 // full GC. 1472 void verify(VerifyOption vo); 1473 1474 // WhiteBox testing support. 1475 virtual bool supports_concurrent_phase_control() const; 1476 virtual const char* const* concurrent_phases() const; 1477 virtual bool request_concurrent_phase(const char* phase); 1478 1479 // The methods below are here for convenience and dispatch the 1480 // appropriate method depending on value of the given VerifyOption 1481 // parameter. The values for that parameter, and their meanings, 1482 // are the same as those above. 1483 1484 bool is_obj_dead_cond(const oop obj, 1485 const HeapRegion* hr, 1486 const VerifyOption vo) const; 1487 1488 bool is_obj_dead_cond(const oop obj, 1489 const VerifyOption vo) const; 1490 1491 G1HeapSummary create_g1_heap_summary(); 1492 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1493 1494 // Printing 1495 private: 1496 void print_heap_regions() const; 1497 void print_regions_on(outputStream* st) const; 1498 1499 public: 1500 virtual void print_on(outputStream* st) const; 1501 virtual void print_extended_on(outputStream* st) const; 1502 virtual void print_on_error(outputStream* st) const; 1503 1504 virtual void print_gc_threads_on(outputStream* st) const; 1505 virtual void gc_threads_do(ThreadClosure* tc) const; 1506 1507 // Override 1508 void print_tracing_info() const; 1509 1510 // The following two methods are helpful for debugging RSet issues. 1511 void print_cset_rsets() PRODUCT_RETURN; 1512 void print_all_rsets() PRODUCT_RETURN; 1513 1514 public: 1515 size_t pending_card_num(); 1516 1517 protected: 1518 size_t _max_heap_capacity; 1519 }; 1520 1521 class G1ParEvacuateFollowersClosure : public VoidClosure { 1522 private: 1523 double _start_term; 1524 double _term_time; 1525 size_t _term_attempts; 1526 1527 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1528 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1529 protected: 1530 G1CollectedHeap* _g1h; 1531 G1ParScanThreadState* _par_scan_state; 1532 RefToScanQueueSet* _queues; 1533 ParallelTaskTerminator* _terminator; 1534 1535 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1536 RefToScanQueueSet* queues() { return _queues; } 1537 ParallelTaskTerminator* terminator() { return _terminator; } 1538 1539 public: 1540 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1541 G1ParScanThreadState* par_scan_state, 1542 RefToScanQueueSet* queues, 1543 ParallelTaskTerminator* terminator) 1544 : _g1h(g1h), _par_scan_state(par_scan_state), 1545 _queues(queues), _terminator(terminator), 1546 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1547 1548 void do_void(); 1549 1550 double term_time() const { return _term_time; } 1551 size_t term_attempts() const { return _term_attempts; } 1552 1553 private: 1554 inline bool offer_termination(); 1555 }; 1556 1557 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP