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/hSpaceCounters.hpp" 46 #include "gc/g1/heapRegionManager.hpp" 47 #include "gc/g1/heapRegionSet.hpp" 48 #include "gc/shared/barrierSet.hpp" 49 #include "gc/shared/collectedHeap.hpp" 50 #include "gc/shared/plab.hpp" 51 #include "gc/shared/preservedMarks.hpp" 52 #include "memory/memRegion.hpp" 53 #include "utilities/stack.hpp" 54 55 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 56 // It uses the "Garbage First" heap organization and algorithm, which 57 // may combine concurrent marking with parallel, incremental compaction of 58 // heap subsets that will yield large amounts of garbage. 59 60 // Forward declarations 61 class HeapRegion; 62 class HRRSCleanupTask; 63 class GenerationSpec; 64 class G1ParScanThreadState; 65 class G1ParScanThreadStateSet; 66 class G1ParScanThreadState; 67 class ObjectClosure; 68 class SpaceClosure; 69 class CompactibleSpaceClosure; 70 class Space; 71 class G1CollectionSet; 72 class G1CollectorPolicy; 73 class G1Policy; 74 class G1HotCardCache; 75 class G1RemSet; 76 class G1YoungRemSetSamplingThread; 77 class GCMemoryManager; 78 class HeapRegionRemSetIterator; 79 class G1ConcurrentMark; 80 class ConcurrentMarkThread; 81 class G1ConcurrentRefine; 82 class GenerationCounters; 83 class STWGCTimer; 84 class G1NewTracer; 85 class EvacuationFailedInfo; 86 class nmethod; 87 class Ticks; 88 class WorkGang; 89 class G1Allocator; 90 class G1ArchiveAllocator; 91 class G1FullGCScope; 92 class G1HeapVerifier; 93 class G1HeapSizingPolicy; 94 class G1HeapSummary; 95 class G1EvacSummary; 96 97 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 98 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 99 100 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 101 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 102 103 // The G1 STW is alive closure. 104 // An instance is embedded into the G1CH and used as the 105 // (optional) _is_alive_non_header closure in the STW 106 // reference processor. It is also extensively used during 107 // reference processing during STW evacuation pauses. 108 class G1STWIsAliveClosure: public BoolObjectClosure { 109 G1CollectedHeap* _g1; 110 public: 111 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 112 bool do_object_b(oop p); 113 }; 114 115 class G1RegionMappingChangedListener : public G1MappingChangedListener { 116 private: 117 void reset_from_card_cache(uint start_idx, size_t num_regions); 118 public: 119 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 120 }; 121 122 class G1CollectedHeap : public CollectedHeap { 123 friend class G1FreeCollectionSetTask; 124 friend class VM_CollectForMetadataAllocation; 125 friend class VM_G1CollectForAllocation; 126 friend class VM_G1CollectFull; 127 friend class VM_G1IncCollectionPause; 128 friend class VMStructs; 129 friend class MutatorAllocRegion; 130 friend class G1GCAllocRegion; 131 friend class G1HeapVerifier; 132 133 // Closures used in implementation. 134 friend class G1ParScanThreadState; 135 friend class G1ParScanThreadStateSet; 136 friend class G1ParTask; 137 friend class G1PLABAllocator; 138 friend class G1PrepareCompactClosure; 139 140 // Other related classes. 141 friend class HeapRegionClaimer; 142 143 // Testing classes. 144 friend class G1CheckCSetFastTableClosure; 145 146 private: 147 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 148 149 WorkGang* _workers; 150 G1CollectorPolicy* _collector_policy; 151 152 GCMemoryManager* _minor_mgr; 153 GCMemoryManager* _major_mgr; 154 155 static size_t _humongous_object_threshold_in_words; 156 157 // The secondary free list which contains regions that have been 158 // freed up during the cleanup process. This will be appended to 159 // the master free list when appropriate. 160 FreeRegionList _secondary_free_list; 161 162 // It keeps track of the old regions. 163 HeapRegionSet _old_set; 164 165 // It keeps track of the humongous regions. 166 HeapRegionSet _humongous_set; 167 168 void eagerly_reclaim_humongous_regions(); 169 // Start a new incremental collection set for the next pause. 170 void start_new_collection_set(); 171 172 // The number of regions we could create by expansion. 173 uint _expansion_regions; 174 175 // The block offset table for the G1 heap. 176 G1BlockOffsetTable* _bot; 177 178 // Tears down the region sets / lists so that they are empty and the 179 // regions on the heap do not belong to a region set / list. The 180 // only exception is the humongous set which we leave unaltered. If 181 // free_list_only is true, it will only tear down the master free 182 // list. It is called before a Full GC (free_list_only == false) or 183 // before heap shrinking (free_list_only == true). 184 void tear_down_region_sets(bool free_list_only); 185 186 // Rebuilds the region sets / lists so that they are repopulated to 187 // reflect the contents of the heap. The only exception is the 188 // humongous set which was not torn down in the first place. If 189 // free_list_only is true, it will only rebuild the master free 190 // list. It is called after a Full GC (free_list_only == false) or 191 // after heap shrinking (free_list_only == true). 192 void rebuild_region_sets(bool free_list_only); 193 194 // Callback for region mapping changed events. 195 G1RegionMappingChangedListener _listener; 196 197 // The sequence of all heap regions in the heap. 198 HeapRegionManager _hrm; 199 200 // Manages all allocations with regions except humongous object allocations. 201 G1Allocator* _allocator; 202 203 // Manages all heap verification. 204 G1HeapVerifier* _verifier; 205 206 // Outside of GC pauses, the number of bytes used in all regions other 207 // than the current allocation region(s). 208 size_t _summary_bytes_used; 209 210 void increase_used(size_t bytes); 211 void decrease_used(size_t bytes); 212 213 void set_used(size_t bytes); 214 215 // Class that handles archive allocation ranges. 216 G1ArchiveAllocator* _archive_allocator; 217 218 // Statistics for each allocation context 219 AllocationContextStats _allocation_context_stats; 220 221 // GC allocation statistics policy for survivors. 222 G1EvacStats _survivor_evac_stats; 223 224 // GC allocation statistics policy for tenured objects. 225 G1EvacStats _old_evac_stats; 226 227 // It specifies whether we should attempt to expand the heap after a 228 // region allocation failure. If heap expansion fails we set this to 229 // false so that we don't re-attempt the heap expansion (it's likely 230 // that subsequent expansion attempts will also fail if one fails). 231 // Currently, it is only consulted during GC and it's reset at the 232 // start of each GC. 233 bool _expand_heap_after_alloc_failure; 234 235 // Helper for monitoring and management support. 236 G1MonitoringSupport* _g1mm; 237 238 // Records whether the region at the given index is (still) a 239 // candidate for eager reclaim. Only valid for humongous start 240 // regions; other regions have unspecified values. Humongous start 241 // regions are initialized at start of collection pause, with 242 // candidates removed from the set as they are found reachable from 243 // roots or the young generation. 244 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 245 protected: 246 bool default_value() const { return false; } 247 public: 248 void clear() { G1BiasedMappedArray<bool>::clear(); } 249 void set_candidate(uint region, bool value) { 250 set_by_index(region, value); 251 } 252 bool is_candidate(uint region) { 253 return get_by_index(region); 254 } 255 }; 256 257 HumongousReclaimCandidates _humongous_reclaim_candidates; 258 // Stores whether during humongous object registration we found candidate regions. 259 // If not, we can skip a few steps. 260 bool _has_humongous_reclaim_candidates; 261 262 volatile uint _gc_time_stamp; 263 264 G1HRPrinter _hr_printer; 265 266 // It decides whether an explicit GC should start a concurrent cycle 267 // instead of doing a STW GC. Currently, a concurrent cycle is 268 // explicitly started if: 269 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 270 // (b) cause == _g1_humongous_allocation 271 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 272 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 273 // (e) cause == _update_allocation_context_stats_inc 274 // (f) cause == _wb_conc_mark 275 bool should_do_concurrent_full_gc(GCCause::Cause cause); 276 277 // indicates whether we are in young or mixed GC mode 278 G1CollectorState _collector_state; 279 280 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 281 // concurrent cycles) we have started. 282 volatile uint _old_marking_cycles_started; 283 284 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 285 // concurrent cycles) we have completed. 286 volatile uint _old_marking_cycles_completed; 287 288 // This is a non-product method that is helpful for testing. It is 289 // called at the end of a GC and artificially expands the heap by 290 // allocating a number of dead regions. This way we can induce very 291 // frequent marking cycles and stress the cleanup / concurrent 292 // cleanup code more (as all the regions that will be allocated by 293 // this method will be found dead by the marking cycle). 294 void allocate_dummy_regions() PRODUCT_RETURN; 295 296 // Clear RSets after a compaction. It also resets the GC time stamps. 297 void clear_rsets_post_compaction(); 298 299 // If the HR printer is active, dump the state of the regions in the 300 // heap after a compaction. 301 void print_hrm_post_compaction(); 302 303 // Create a memory mapper for auxiliary data structures of the given size and 304 // translation factor. 305 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 306 size_t size, 307 size_t translation_factor); 308 309 static G1Policy* create_g1_policy(STWGCTimer* gc_timer); 310 311 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 312 313 // These are macros so that, if the assert fires, we get the correct 314 // line number, file, etc. 315 316 #define heap_locking_asserts_params(_extra_message_) \ 317 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 318 (_extra_message_), \ 319 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 320 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 321 BOOL_TO_STR(Thread::current()->is_VM_thread()) 322 323 #define assert_heap_locked() \ 324 do { \ 325 assert(Heap_lock->owned_by_self(), \ 326 heap_locking_asserts_params("should be holding the Heap_lock")); \ 327 } while (0) 328 329 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 330 do { \ 331 assert(Heap_lock->owned_by_self() || \ 332 (SafepointSynchronize::is_at_safepoint() && \ 333 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 334 heap_locking_asserts_params("should be holding the Heap_lock or " \ 335 "should be at a safepoint")); \ 336 } while (0) 337 338 #define assert_heap_locked_and_not_at_safepoint() \ 339 do { \ 340 assert(Heap_lock->owned_by_self() && \ 341 !SafepointSynchronize::is_at_safepoint(), \ 342 heap_locking_asserts_params("should be holding the Heap_lock and " \ 343 "should not be at a safepoint")); \ 344 } while (0) 345 346 #define assert_heap_not_locked() \ 347 do { \ 348 assert(!Heap_lock->owned_by_self(), \ 349 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 350 } while (0) 351 352 #define assert_heap_not_locked_and_not_at_safepoint() \ 353 do { \ 354 assert(!Heap_lock->owned_by_self() && \ 355 !SafepointSynchronize::is_at_safepoint(), \ 356 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 357 "should not be at a safepoint")); \ 358 } while (0) 359 360 #define assert_at_safepoint(_should_be_vm_thread_) \ 361 do { \ 362 assert(SafepointSynchronize::is_at_safepoint() && \ 363 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 364 heap_locking_asserts_params("should be at a safepoint")); \ 365 } while (0) 366 367 #define assert_not_at_safepoint() \ 368 do { \ 369 assert(!SafepointSynchronize::is_at_safepoint(), \ 370 heap_locking_asserts_params("should not be at a safepoint")); \ 371 } while (0) 372 373 protected: 374 375 // The young region list. 376 G1EdenRegions _eden; 377 G1SurvivorRegions _survivor; 378 379 STWGCTimer* _gc_timer_stw; 380 381 G1NewTracer* _gc_tracer_stw; 382 383 // The current policy object for the collector. 384 G1Policy* _g1_policy; 385 G1HeapSizingPolicy* _heap_sizing_policy; 386 387 G1CollectionSet _collection_set; 388 389 // This is the second level of trying to allocate a new region. If 390 // new_region() didn't find a region on the free_list, this call will 391 // check whether there's anything available on the 392 // secondary_free_list and/or wait for more regions to appear on 393 // that list, if _free_regions_coming is set. 394 HeapRegion* new_region_try_secondary_free_list(bool is_old); 395 396 // Try to allocate a single non-humongous HeapRegion sufficient for 397 // an allocation of the given word_size. If do_expand is true, 398 // attempt to expand the heap if necessary to satisfy the allocation 399 // request. If the region is to be used as an old region or for a 400 // humongous object, set is_old to true. If not, to false. 401 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 402 403 // Initialize a contiguous set of free regions of length num_regions 404 // and starting at index first so that they appear as a single 405 // humongous region. 406 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 407 uint num_regions, 408 size_t word_size, 409 AllocationContext_t context); 410 411 // Attempt to allocate a humongous object of the given size. Return 412 // NULL if unsuccessful. 413 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 414 415 // The following two methods, allocate_new_tlab() and 416 // mem_allocate(), are the two main entry points from the runtime 417 // into the G1's allocation routines. They have the following 418 // assumptions: 419 // 420 // * They should both be called outside safepoints. 421 // 422 // * They should both be called without holding the Heap_lock. 423 // 424 // * All allocation requests for new TLABs should go to 425 // allocate_new_tlab(). 426 // 427 // * All non-TLAB allocation requests should go to mem_allocate(). 428 // 429 // * If either call cannot satisfy the allocation request using the 430 // current allocating region, they will try to get a new one. If 431 // this fails, they will attempt to do an evacuation pause and 432 // retry the allocation. 433 // 434 // * If all allocation attempts fail, even after trying to schedule 435 // an evacuation pause, allocate_new_tlab() will return NULL, 436 // whereas mem_allocate() will attempt a heap expansion and/or 437 // schedule a Full GC. 438 // 439 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 440 // should never be called with word_size being humongous. All 441 // humongous allocation requests should go to mem_allocate() which 442 // will satisfy them with a special path. 443 444 virtual HeapWord* allocate_new_tlab(size_t word_size); 445 446 virtual HeapWord* mem_allocate(size_t word_size, 447 bool* gc_overhead_limit_was_exceeded); 448 449 // The following three methods take a gc_count_before_ret 450 // parameter which is used to return the GC count if the method 451 // returns NULL. Given that we are required to read the GC count 452 // while holding the Heap_lock, and these paths will take the 453 // Heap_lock at some point, it's easier to get them to read the GC 454 // count while holding the Heap_lock before they return NULL instead 455 // of the caller (namely: mem_allocate()) having to also take the 456 // Heap_lock just to read the GC count. 457 458 // First-level mutator allocation attempt: try to allocate out of 459 // the mutator alloc region without taking the Heap_lock. This 460 // should only be used for non-humongous allocations. 461 inline HeapWord* attempt_allocation(size_t word_size, 462 uint* gc_count_before_ret, 463 uint* gclocker_retry_count_ret); 464 465 // Second-level mutator allocation attempt: take the Heap_lock and 466 // retry the allocation attempt, potentially scheduling a GC 467 // pause. This should only be used for non-humongous allocations. 468 HeapWord* attempt_allocation_slow(size_t word_size, 469 AllocationContext_t context, 470 uint* gc_count_before_ret, 471 uint* gclocker_retry_count_ret); 472 473 // Takes the Heap_lock and attempts a humongous allocation. It can 474 // potentially schedule a GC pause. 475 HeapWord* attempt_allocation_humongous(size_t word_size, 476 uint* gc_count_before_ret, 477 uint* gclocker_retry_count_ret); 478 479 // Allocation attempt that should be called during safepoints (e.g., 480 // at the end of a successful GC). expect_null_mutator_alloc_region 481 // specifies whether the mutator alloc region is expected to be NULL 482 // or not. 483 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 484 AllocationContext_t context, 485 bool expect_null_mutator_alloc_region); 486 487 // These methods are the "callbacks" from the G1AllocRegion class. 488 489 // For mutator alloc regions. 490 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 491 void retire_mutator_alloc_region(HeapRegion* alloc_region, 492 size_t allocated_bytes); 493 494 // For GC alloc regions. 495 bool has_more_regions(InCSetState dest); 496 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 497 void retire_gc_alloc_region(HeapRegion* alloc_region, 498 size_t allocated_bytes, InCSetState dest); 499 500 // - if explicit_gc is true, the GC is for a System.gc() etc, 501 // otherwise it's for a failed allocation. 502 // - if clear_all_soft_refs is true, all soft references should be 503 // cleared during the GC. 504 // - it returns false if it is unable to do the collection due to the 505 // GC locker being active, true otherwise. 506 bool do_full_collection(bool explicit_gc, 507 bool clear_all_soft_refs); 508 509 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 510 virtual void do_full_collection(bool clear_all_soft_refs); 511 512 // Resize the heap if necessary after a full collection. 513 void resize_if_necessary_after_full_collection(); 514 515 // Callback from VM_G1CollectForAllocation operation. 516 // This function does everything necessary/possible to satisfy a 517 // failed allocation request (including collection, expansion, etc.) 518 HeapWord* satisfy_failed_allocation(size_t word_size, 519 AllocationContext_t context, 520 bool* succeeded); 521 private: 522 // Internal helpers used during full GC to split it up to 523 // increase readability. 524 void do_full_collection_inner(G1FullGCScope* scope); 525 void abort_concurrent_cycle(); 526 void verify_before_full_collection(bool explicit_gc); 527 void prepare_heap_for_full_collection(); 528 void prepare_heap_for_mutators(); 529 void abort_refinement(); 530 void verify_after_full_collection(); 531 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 532 533 // Helper method for satisfy_failed_allocation() 534 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 535 AllocationContext_t context, 536 bool do_gc, 537 bool clear_all_soft_refs, 538 bool expect_null_mutator_alloc_region, 539 bool* gc_succeeded); 540 541 protected: 542 // Attempting to expand the heap sufficiently 543 // to support an allocation of the given "word_size". If 544 // successful, perform the allocation and return the address of the 545 // allocated block, or else "NULL". 546 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 547 548 // Preserve any referents discovered by concurrent marking that have not yet been 549 // copied by the STW pause. 550 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 551 // Process any reference objects discovered during 552 // an incremental evacuation pause. 553 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 554 555 // Enqueue any remaining discovered references 556 // after processing. 557 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 558 559 // Merges the information gathered on a per-thread basis for all worker threads 560 // during GC into global variables. 561 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 562 public: 563 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 564 565 WorkGang* workers() const { return _workers; } 566 567 G1Allocator* allocator() { 568 return _allocator; 569 } 570 571 G1HeapVerifier* verifier() { 572 return _verifier; 573 } 574 575 G1MonitoringSupport* g1mm() { 576 assert(_g1mm != NULL, "should have been initialized"); 577 return _g1mm; 578 } 579 580 // Expand the garbage-first heap by at least the given size (in bytes!). 581 // Returns true if the heap was expanded by the requested amount; 582 // false otherwise. 583 // (Rounds up to a HeapRegion boundary.) 584 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 585 586 // Returns the PLAB statistics for a given destination. 587 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 588 589 // Determines PLAB size for a given destination. 590 inline size_t desired_plab_sz(InCSetState dest); 591 592 inline AllocationContextStats& allocation_context_stats(); 593 594 // Do anything common to GC's. 595 void gc_prologue(bool full); 596 void gc_epilogue(bool full); 597 598 // Modify the reclaim candidate set and test for presence. 599 // These are only valid for starts_humongous regions. 600 inline void set_humongous_reclaim_candidate(uint region, bool value); 601 inline bool is_humongous_reclaim_candidate(uint region); 602 603 // Remove from the reclaim candidate set. Also remove from the 604 // collection set so that later encounters avoid the slow path. 605 inline void set_humongous_is_live(oop obj); 606 607 // Register the given region to be part of the collection set. 608 inline void register_humongous_region_with_cset(uint index); 609 // Register regions with humongous objects (actually on the start region) in 610 // the in_cset_fast_test table. 611 void register_humongous_regions_with_cset(); 612 // We register a region with the fast "in collection set" test. We 613 // simply set to true the array slot corresponding to this region. 614 void register_young_region_with_cset(HeapRegion* r) { 615 _in_cset_fast_test.set_in_young(r->hrm_index()); 616 } 617 void register_old_region_with_cset(HeapRegion* r) { 618 _in_cset_fast_test.set_in_old(r->hrm_index()); 619 } 620 inline void register_ext_region_with_cset(HeapRegion* r) { 621 _in_cset_fast_test.set_ext(r->hrm_index()); 622 } 623 void clear_in_cset(const HeapRegion* hr) { 624 _in_cset_fast_test.clear(hr); 625 } 626 627 void clear_cset_fast_test() { 628 _in_cset_fast_test.clear(); 629 } 630 631 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 632 633 // This is called at the start of either a concurrent cycle or a Full 634 // GC to update the number of old marking cycles started. 635 void increment_old_marking_cycles_started(); 636 637 // This is called at the end of either a concurrent cycle or a Full 638 // GC to update the number of old marking cycles completed. Those two 639 // can happen in a nested fashion, i.e., we start a concurrent 640 // cycle, a Full GC happens half-way through it which ends first, 641 // and then the cycle notices that a Full GC happened and ends 642 // too. The concurrent parameter is a boolean to help us do a bit 643 // tighter consistency checking in the method. If concurrent is 644 // false, the caller is the inner caller in the nesting (i.e., the 645 // Full GC). If concurrent is true, the caller is the outer caller 646 // in this nesting (i.e., the concurrent cycle). Further nesting is 647 // not currently supported. The end of this call also notifies 648 // the FullGCCount_lock in case a Java thread is waiting for a full 649 // GC to happen (e.g., it called System.gc() with 650 // +ExplicitGCInvokesConcurrent). 651 void increment_old_marking_cycles_completed(bool concurrent); 652 653 uint old_marking_cycles_completed() { 654 return _old_marking_cycles_completed; 655 } 656 657 G1HRPrinter* hr_printer() { return &_hr_printer; } 658 659 // Allocates a new heap region instance. 660 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 661 662 // Allocate the highest free region in the reserved heap. This will commit 663 // regions as necessary. 664 HeapRegion* alloc_highest_free_region(); 665 666 // Frees a non-humongous region by initializing its contents and 667 // adding it to the free list that's passed as a parameter (this is 668 // usually a local list which will be appended to the master free 669 // list later). The used bytes of freed regions are accumulated in 670 // pre_used. If skip_remset is true, the region's RSet will not be freed 671 // up. If skip_hot_card_cache is true, the region's hot card cache will not 672 // be freed up. The assumption is that this will be done later. 673 // The locked parameter indicates if the caller has already taken 674 // care of proper synchronization. This may allow some optimizations. 675 void free_region(HeapRegion* hr, 676 FreeRegionList* free_list, 677 bool skip_remset, 678 bool skip_hot_card_cache = false, 679 bool locked = false); 680 681 // It dirties the cards that cover the block so that the post 682 // write barrier never queues anything when updating objects on this 683 // block. It is assumed (and in fact we assert) that the block 684 // belongs to a young region. 685 inline void dirty_young_block(HeapWord* start, size_t word_size); 686 687 // Frees a humongous region by collapsing it into individual regions 688 // and calling free_region() for each of them. The freed regions 689 // will be added to the free list that's passed as a parameter (this 690 // is usually a local list which will be appended to the master free 691 // list later). The used bytes of freed regions are accumulated in 692 // pre_used. If skip_remset is true, the region's RSet will not be freed 693 // up. The assumption is that this will be done later. 694 void free_humongous_region(HeapRegion* hr, 695 FreeRegionList* free_list, 696 bool skip_remset); 697 698 // Facility for allocating in 'archive' regions in high heap memory and 699 // recording the allocated ranges. These should all be called from the 700 // VM thread at safepoints, without the heap lock held. They can be used 701 // to create and archive a set of heap regions which can be mapped at the 702 // same fixed addresses in a subsequent JVM invocation. 703 void begin_archive_alloc_range(bool open = false); 704 705 // Check if the requested size would be too large for an archive allocation. 706 bool is_archive_alloc_too_large(size_t word_size); 707 708 // Allocate memory of the requested size from the archive region. This will 709 // return NULL if the size is too large or if no memory is available. It 710 // does not trigger a garbage collection. 711 HeapWord* archive_mem_allocate(size_t word_size); 712 713 // Optionally aligns the end address and returns the allocated ranges in 714 // an array of MemRegions in order of ascending addresses. 715 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 716 size_t end_alignment_in_bytes = 0); 717 718 // Facility for allocating a fixed range within the heap and marking 719 // the containing regions as 'archive'. For use at JVM init time, when the 720 // caller may mmap archived heap data at the specified range(s). 721 // Verify that the MemRegions specified in the argument array are within the 722 // reserved heap. 723 bool check_archive_addresses(MemRegion* range, size_t count); 724 725 // Commit the appropriate G1 regions containing the specified MemRegions 726 // and mark them as 'archive' regions. The regions in the array must be 727 // non-overlapping and in order of ascending address. 728 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 729 730 // Insert any required filler objects in the G1 regions around the specified 731 // ranges to make the regions parseable. This must be called after 732 // alloc_archive_regions, and after class loading has occurred. 733 void fill_archive_regions(MemRegion* range, size_t count); 734 735 // For each of the specified MemRegions, uncommit the containing G1 regions 736 // which had been allocated by alloc_archive_regions. This should be called 737 // rather than fill_archive_regions at JVM init time if the archive file 738 // mapping failed, with the same non-overlapping and sorted MemRegion array. 739 void dealloc_archive_regions(MemRegion* range, size_t count); 740 741 protected: 742 743 // Shrink the garbage-first heap by at most the given size (in bytes!). 744 // (Rounds down to a HeapRegion boundary.) 745 virtual void shrink(size_t expand_bytes); 746 void shrink_helper(size_t expand_bytes); 747 748 #if TASKQUEUE_STATS 749 static void print_taskqueue_stats_hdr(outputStream* const st); 750 void print_taskqueue_stats() const; 751 void reset_taskqueue_stats(); 752 #endif // TASKQUEUE_STATS 753 754 // Schedule the VM operation that will do an evacuation pause to 755 // satisfy an allocation request of word_size. *succeeded will 756 // return whether the VM operation was successful (it did do an 757 // evacuation pause) or not (another thread beat us to it or the GC 758 // locker was active). Given that we should not be holding the 759 // Heap_lock when we enter this method, we will pass the 760 // gc_count_before (i.e., total_collections()) as a parameter since 761 // it has to be read while holding the Heap_lock. Currently, both 762 // methods that call do_collection_pause() release the Heap_lock 763 // before the call, so it's easy to read gc_count_before just before. 764 HeapWord* do_collection_pause(size_t word_size, 765 uint gc_count_before, 766 bool* succeeded, 767 GCCause::Cause gc_cause); 768 769 void wait_for_root_region_scanning(); 770 771 // The guts of the incremental collection pause, executed by the vm 772 // thread. It returns false if it is unable to do the collection due 773 // to the GC locker being active, true otherwise 774 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 775 776 // Actually do the work of evacuating the collection set. 777 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 778 779 void pre_evacuate_collection_set(); 780 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 781 782 // Print the header for the per-thread termination statistics. 783 static void print_termination_stats_hdr(); 784 // Print actual per-thread termination statistics. 785 void print_termination_stats(uint worker_id, 786 double elapsed_ms, 787 double strong_roots_ms, 788 double term_ms, 789 size_t term_attempts, 790 size_t alloc_buffer_waste, 791 size_t undo_waste) const; 792 // Update object copying statistics. 793 void record_obj_copy_mem_stats(); 794 795 // The hot card cache for remembered set insertion optimization. 796 G1HotCardCache* _hot_card_cache; 797 798 // The g1 remembered set of the heap. 799 G1RemSet* _g1_rem_set; 800 801 // A set of cards that cover the objects for which the Rsets should be updated 802 // concurrently after the collection. 803 DirtyCardQueueSet _dirty_card_queue_set; 804 805 // After a collection pause, convert the regions in the collection set into free 806 // regions. 807 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 808 809 // Abandon the current collection set without recording policy 810 // statistics or updating free lists. 811 void abandon_collection_set(G1CollectionSet* collection_set); 812 813 // The concurrent marker (and the thread it runs in.) 814 G1ConcurrentMark* _cm; 815 ConcurrentMarkThread* _cmThread; 816 817 // The concurrent refiner. 818 G1ConcurrentRefine* _cr; 819 820 // The parallel task queues 821 RefToScanQueueSet *_task_queues; 822 823 // True iff a evacuation has failed in the current collection. 824 bool _evacuation_failed; 825 826 EvacuationFailedInfo* _evacuation_failed_info_array; 827 828 // Failed evacuations cause some logical from-space objects to have 829 // forwarding pointers to themselves. Reset them. 830 void remove_self_forwarding_pointers(); 831 832 // Restore the objects in the regions in the collection set after an 833 // evacuation failure. 834 void restore_after_evac_failure(); 835 836 PreservedMarksSet _preserved_marks_set; 837 838 // Preserve the mark of "obj", if necessary, in preparation for its mark 839 // word being overwritten with a self-forwarding-pointer. 840 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 841 842 #ifndef PRODUCT 843 // Support for forcing evacuation failures. Analogous to 844 // PromotionFailureALot for the other collectors. 845 846 // Records whether G1EvacuationFailureALot should be in effect 847 // for the current GC 848 bool _evacuation_failure_alot_for_current_gc; 849 850 // Used to record the GC number for interval checking when 851 // determining whether G1EvaucationFailureALot is in effect 852 // for the current GC. 853 size_t _evacuation_failure_alot_gc_number; 854 855 // Count of the number of evacuations between failures. 856 volatile size_t _evacuation_failure_alot_count; 857 858 // Set whether G1EvacuationFailureALot should be in effect 859 // for the current GC (based upon the type of GC and which 860 // command line flags are set); 861 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 862 bool during_initial_mark, 863 bool during_marking); 864 865 inline void set_evacuation_failure_alot_for_current_gc(); 866 867 // Return true if it's time to cause an evacuation failure. 868 inline bool evacuation_should_fail(); 869 870 // Reset the G1EvacuationFailureALot counters. Should be called at 871 // the end of an evacuation pause in which an evacuation failure occurred. 872 inline void reset_evacuation_should_fail(); 873 #endif // !PRODUCT 874 875 // ("Weak") Reference processing support. 876 // 877 // G1 has 2 instances of the reference processor class. One 878 // (_ref_processor_cm) handles reference object discovery 879 // and subsequent processing during concurrent marking cycles. 880 // 881 // The other (_ref_processor_stw) handles reference object 882 // discovery and processing during full GCs and incremental 883 // evacuation pauses. 884 // 885 // During an incremental pause, reference discovery will be 886 // temporarily disabled for _ref_processor_cm and will be 887 // enabled for _ref_processor_stw. At the end of the evacuation 888 // pause references discovered by _ref_processor_stw will be 889 // processed and discovery will be disabled. The previous 890 // setting for reference object discovery for _ref_processor_cm 891 // will be re-instated. 892 // 893 // At the start of marking: 894 // * Discovery by the CM ref processor is verified to be inactive 895 // and it's discovered lists are empty. 896 // * Discovery by the CM ref processor is then enabled. 897 // 898 // At the end of marking: 899 // * Any references on the CM ref processor's discovered 900 // lists are processed (possibly MT). 901 // 902 // At the start of full GC we: 903 // * Disable discovery by the CM ref processor and 904 // empty CM ref processor's discovered lists 905 // (without processing any entries). 906 // * Verify that the STW ref processor is inactive and it's 907 // discovered lists are empty. 908 // * Temporarily set STW ref processor discovery as single threaded. 909 // * Temporarily clear the STW ref processor's _is_alive_non_header 910 // field. 911 // * Finally enable discovery by the STW ref processor. 912 // 913 // The STW ref processor is used to record any discovered 914 // references during the full GC. 915 // 916 // At the end of a full GC we: 917 // * Enqueue any reference objects discovered by the STW ref processor 918 // that have non-live referents. This has the side-effect of 919 // making the STW ref processor inactive by disabling discovery. 920 // * Verify that the CM ref processor is still inactive 921 // and no references have been placed on it's discovered 922 // lists (also checked as a precondition during initial marking). 923 924 // The (stw) reference processor... 925 ReferenceProcessor* _ref_processor_stw; 926 927 // During reference object discovery, the _is_alive_non_header 928 // closure (if non-null) is applied to the referent object to 929 // determine whether the referent is live. If so then the 930 // reference object does not need to be 'discovered' and can 931 // be treated as a regular oop. This has the benefit of reducing 932 // the number of 'discovered' reference objects that need to 933 // be processed. 934 // 935 // Instance of the is_alive closure for embedding into the 936 // STW reference processor as the _is_alive_non_header field. 937 // Supplying a value for the _is_alive_non_header field is 938 // optional but doing so prevents unnecessary additions to 939 // the discovered lists during reference discovery. 940 G1STWIsAliveClosure _is_alive_closure_stw; 941 942 // The (concurrent marking) reference processor... 943 ReferenceProcessor* _ref_processor_cm; 944 945 // Instance of the concurrent mark is_alive closure for embedding 946 // into the Concurrent Marking reference processor as the 947 // _is_alive_non_header field. Supplying a value for the 948 // _is_alive_non_header field is optional but doing so prevents 949 // unnecessary additions to the discovered lists during reference 950 // discovery. 951 G1CMIsAliveClosure _is_alive_closure_cm; 952 953 volatile bool _free_regions_coming; 954 955 public: 956 957 RefToScanQueue *task_queue(uint i) const; 958 959 uint num_task_queues() const; 960 961 // A set of cards where updates happened during the GC 962 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 963 964 // Create a G1CollectedHeap with the specified policy. 965 // Must call the initialize method afterwards. 966 // May not return if something goes wrong. 967 G1CollectedHeap(G1CollectorPolicy* policy); 968 969 private: 970 jint initialize_concurrent_refinement(); 971 jint initialize_young_gen_sampling_thread(); 972 public: 973 // Initialize the G1CollectedHeap to have the initial and 974 // maximum sizes and remembered and barrier sets 975 // specified by the policy object. 976 jint initialize(); 977 978 virtual void stop(); 979 virtual void safepoint_synchronize_begin(); 980 virtual void safepoint_synchronize_end(); 981 982 // Return the (conservative) maximum heap alignment for any G1 heap 983 static size_t conservative_max_heap_alignment(); 984 985 // Does operations required after initialization has been done. 986 void post_initialize(); 987 988 // Initialize weak reference processing. 989 void ref_processing_init(); 990 991 virtual Name kind() const { 992 return CollectedHeap::G1CollectedHeap; 993 } 994 995 virtual const char* name() const { 996 return "G1"; 997 } 998 999 const G1CollectorState* collector_state() const { return &_collector_state; } 1000 G1CollectorState* collector_state() { return &_collector_state; } 1001 1002 // The current policy object for the collector. 1003 G1Policy* g1_policy() const { return _g1_policy; } 1004 1005 const G1CollectionSet* collection_set() const { return &_collection_set; } 1006 G1CollectionSet* collection_set() { return &_collection_set; } 1007 1008 virtual CollectorPolicy* collector_policy() const; 1009 1010 // Adaptive size policy. No such thing for g1. 1011 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1012 1013 virtual GrowableArray<GCMemoryManager*> memory_managers(); 1014 virtual GrowableArray<MemoryPool*> memory_pools(); 1015 1016 // The rem set and barrier set. 1017 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1018 1019 // Try to minimize the remembered set. 1020 void scrub_rem_set(); 1021 1022 uint get_gc_time_stamp() { 1023 return _gc_time_stamp; 1024 } 1025 1026 inline void reset_gc_time_stamp(); 1027 1028 void check_gc_time_stamps() PRODUCT_RETURN; 1029 1030 inline void increment_gc_time_stamp(); 1031 1032 // Reset the given region's GC timestamp. If it's starts humongous, 1033 // also reset the GC timestamp of its corresponding 1034 // continues humongous regions too. 1035 void reset_gc_time_stamps(HeapRegion* hr); 1036 1037 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1038 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1039 1040 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1041 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1042 1043 // The shared block offset table array. 1044 G1BlockOffsetTable* bot() const { return _bot; } 1045 1046 // Reference Processing accessors 1047 1048 // The STW reference processor.... 1049 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1050 1051 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1052 1053 // The Concurrent Marking reference processor... 1054 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1055 1056 size_t unused_committed_regions_in_bytes() const; 1057 virtual size_t capacity() const; 1058 virtual size_t used() const; 1059 // This should be called when we're not holding the heap lock. The 1060 // result might be a bit inaccurate. 1061 size_t used_unlocked() const; 1062 size_t recalculate_used() const; 1063 1064 // These virtual functions do the actual allocation. 1065 // Some heaps may offer a contiguous region for shared non-blocking 1066 // allocation, via inlined code (by exporting the address of the top and 1067 // end fields defining the extent of the contiguous allocation region.) 1068 // But G1CollectedHeap doesn't yet support this. 1069 1070 virtual bool is_maximal_no_gc() const { 1071 return _hrm.available() == 0; 1072 } 1073 1074 // The current number of regions in the heap. 1075 uint num_regions() const { return _hrm.length(); } 1076 1077 // The max number of regions in the heap. 1078 uint max_regions() const { return _hrm.max_length(); } 1079 1080 // The number of regions that are completely free. 1081 uint num_free_regions() const { return _hrm.num_free_regions(); } 1082 1083 MemoryUsage get_auxiliary_data_memory_usage() const { 1084 return _hrm.get_auxiliary_data_memory_usage(); 1085 } 1086 1087 // The number of regions that are not completely free. 1088 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1089 1090 #ifdef ASSERT 1091 bool is_on_master_free_list(HeapRegion* hr) { 1092 return _hrm.is_free(hr); 1093 } 1094 #endif // ASSERT 1095 1096 // Wrapper for the region list operations that can be called from 1097 // methods outside this class. 1098 1099 void secondary_free_list_add(FreeRegionList* list) { 1100 _secondary_free_list.add_ordered(list); 1101 } 1102 1103 void append_secondary_free_list() { 1104 _hrm.insert_list_into_free_list(&_secondary_free_list); 1105 } 1106 1107 void append_secondary_free_list_if_not_empty_with_lock() { 1108 // If the secondary free list looks empty there's no reason to 1109 // take the lock and then try to append it. 1110 if (!_secondary_free_list.is_empty()) { 1111 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1112 append_secondary_free_list(); 1113 } 1114 } 1115 1116 inline void old_set_add(HeapRegion* hr); 1117 inline void old_set_remove(HeapRegion* hr); 1118 1119 size_t non_young_capacity_bytes() { 1120 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1121 } 1122 1123 void set_free_regions_coming(); 1124 void reset_free_regions_coming(); 1125 bool free_regions_coming() { return _free_regions_coming; } 1126 void wait_while_free_regions_coming(); 1127 1128 // Determine whether the given region is one that we are using as an 1129 // old GC alloc region. 1130 bool is_old_gc_alloc_region(HeapRegion* hr); 1131 1132 // Perform a collection of the heap; intended for use in implementing 1133 // "System.gc". This probably implies as full a collection as the 1134 // "CollectedHeap" supports. 1135 virtual void collect(GCCause::Cause cause); 1136 1137 virtual bool copy_allocation_context_stats(const jint* contexts, 1138 jlong* totals, 1139 jbyte* accuracy, 1140 jint len); 1141 1142 // True iff an evacuation has failed in the most-recent collection. 1143 bool evacuation_failed() { return _evacuation_failed; } 1144 1145 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1146 void prepend_to_freelist(FreeRegionList* list); 1147 void decrement_summary_bytes(size_t bytes); 1148 1149 virtual bool is_in(const void* p) const; 1150 #ifdef ASSERT 1151 // Returns whether p is in one of the available areas of the heap. Slow but 1152 // extensive version. 1153 bool is_in_exact(const void* p) const; 1154 #endif 1155 1156 // Return "TRUE" iff the given object address is within the collection 1157 // set. Assumes that the reference points into the heap. 1158 inline bool is_in_cset(const HeapRegion *hr); 1159 inline bool is_in_cset(oop obj); 1160 inline bool is_in_cset(HeapWord* addr); 1161 1162 inline bool is_in_cset_or_humongous(const oop obj); 1163 1164 private: 1165 // This array is used for a quick test on whether a reference points into 1166 // the collection set or not. Each of the array's elements denotes whether the 1167 // corresponding region is in the collection set or not. 1168 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1169 1170 public: 1171 1172 inline InCSetState in_cset_state(const oop obj); 1173 1174 // Return "TRUE" iff the given object address is in the reserved 1175 // region of g1. 1176 bool is_in_g1_reserved(const void* p) const { 1177 return _hrm.reserved().contains(p); 1178 } 1179 1180 // Returns a MemRegion that corresponds to the space that has been 1181 // reserved for the heap 1182 MemRegion g1_reserved() const { 1183 return _hrm.reserved(); 1184 } 1185 1186 virtual bool is_in_closed_subset(const void* p) const; 1187 1188 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1189 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1190 } 1191 1192 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1193 1194 // Iteration functions. 1195 1196 // Iterate over all objects, calling "cl.do_object" on each. 1197 virtual void object_iterate(ObjectClosure* cl); 1198 1199 virtual void safe_object_iterate(ObjectClosure* cl) { 1200 object_iterate(cl); 1201 } 1202 1203 // Iterate over heap regions, in address order, terminating the 1204 // iteration early if the "doHeapRegion" method returns "true". 1205 void heap_region_iterate(HeapRegionClosure* blk) const; 1206 1207 // Return the region with the given index. It assumes the index is valid. 1208 inline HeapRegion* region_at(uint index) const; 1209 1210 // Return the next region (by index) that is part of the same 1211 // humongous object that hr is part of. 1212 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1213 1214 // Calculate the region index of the given address. Given address must be 1215 // within the heap. 1216 inline uint addr_to_region(HeapWord* addr) const; 1217 1218 inline HeapWord* bottom_addr_for_region(uint index) const; 1219 1220 // Two functions to iterate over the heap regions in parallel. Threads 1221 // compete using the HeapRegionClaimer to claim the regions before 1222 // applying the closure on them. 1223 // The _from_worker_offset version uses the HeapRegionClaimer and 1224 // the worker id to calculate a start offset to prevent all workers to 1225 // start from the point. 1226 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1227 HeapRegionClaimer* hrclaimer, 1228 uint worker_id) const; 1229 1230 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1231 HeapRegionClaimer* hrclaimer) const; 1232 1233 // Iterate over the regions (if any) in the current collection set. 1234 void collection_set_iterate(HeapRegionClosure* blk); 1235 1236 // Iterate over the regions (if any) in the current collection set. Starts the 1237 // iteration over the entire collection set so that the start regions of a given 1238 // worker id over the set active_workers are evenly spread across the set of 1239 // collection set regions. 1240 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1241 1242 // Returns the HeapRegion that contains addr. addr must not be NULL. 1243 template <class T> 1244 inline HeapRegion* heap_region_containing(const T addr) const; 1245 1246 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1247 // each address in the (reserved) heap is a member of exactly 1248 // one block. The defining characteristic of a block is that it is 1249 // possible to find its size, and thus to progress forward to the next 1250 // block. (Blocks may be of different sizes.) Thus, blocks may 1251 // represent Java objects, or they might be free blocks in a 1252 // free-list-based heap (or subheap), as long as the two kinds are 1253 // distinguishable and the size of each is determinable. 1254 1255 // Returns the address of the start of the "block" that contains the 1256 // address "addr". We say "blocks" instead of "object" since some heaps 1257 // may not pack objects densely; a chunk may either be an object or a 1258 // non-object. 1259 virtual HeapWord* block_start(const void* addr) const; 1260 1261 // Requires "addr" to be the start of a chunk, and returns its size. 1262 // "addr + size" is required to be the start of a new chunk, or the end 1263 // of the active area of the heap. 1264 virtual size_t block_size(const HeapWord* addr) const; 1265 1266 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1267 // the block is an object. 1268 virtual bool block_is_obj(const HeapWord* addr) const; 1269 1270 // Section on thread-local allocation buffers (TLABs) 1271 // See CollectedHeap for semantics. 1272 1273 bool supports_tlab_allocation() const; 1274 size_t tlab_capacity(Thread* ignored) const; 1275 size_t tlab_used(Thread* ignored) const; 1276 size_t max_tlab_size() const; 1277 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1278 1279 // Can a compiler initialize a new object without store barriers? 1280 // This permission only extends from the creation of a new object 1281 // via a TLAB up to the first subsequent safepoint. If such permission 1282 // is granted for this heap type, the compiler promises to call 1283 // defer_store_barrier() below on any slow path allocation of 1284 // a new object for which such initializing store barriers will 1285 // have been elided. G1, like CMS, allows this, but should be 1286 // ready to provide a compensating write barrier as necessary 1287 // if that storage came out of a non-young region. The efficiency 1288 // of this implementation depends crucially on being able to 1289 // answer very efficiently in constant time whether a piece of 1290 // storage in the heap comes from a young region or not. 1291 // See ReduceInitialCardMarks. 1292 virtual bool can_elide_tlab_store_barriers() const { 1293 return true; 1294 } 1295 1296 virtual bool card_mark_must_follow_store() const { 1297 return true; 1298 } 1299 1300 inline bool is_in_young(const oop obj); 1301 1302 // We don't need barriers for initializing stores to objects 1303 // in the young gen: for the SATB pre-barrier, there is no 1304 // pre-value that needs to be remembered; for the remembered-set 1305 // update logging post-barrier, we don't maintain remembered set 1306 // information for young gen objects. 1307 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1308 1309 // Returns "true" iff the given word_size is "very large". 1310 static bool is_humongous(size_t word_size) { 1311 // Note this has to be strictly greater-than as the TLABs 1312 // are capped at the humongous threshold and we want to 1313 // ensure that we don't try to allocate a TLAB as 1314 // humongous and that we don't allocate a humongous 1315 // object in a TLAB. 1316 return word_size > _humongous_object_threshold_in_words; 1317 } 1318 1319 // Returns the humongous threshold for a specific region size 1320 static size_t humongous_threshold_for(size_t region_size) { 1321 return (region_size / 2); 1322 } 1323 1324 // Returns the number of regions the humongous object of the given word size 1325 // requires. 1326 static size_t humongous_obj_size_in_regions(size_t word_size); 1327 1328 // Print the maximum heap capacity. 1329 virtual size_t max_capacity() const; 1330 1331 virtual jlong millis_since_last_gc(); 1332 1333 1334 // Convenience function to be used in situations where the heap type can be 1335 // asserted to be this type. 1336 static G1CollectedHeap* heap(); 1337 1338 void set_region_short_lived_locked(HeapRegion* hr); 1339 // add appropriate methods for any other surv rate groups 1340 1341 const G1SurvivorRegions* survivor() const { return &_survivor; } 1342 1343 uint survivor_regions_count() const { 1344 return _survivor.length(); 1345 } 1346 1347 uint eden_regions_count() const { 1348 return _eden.length(); 1349 } 1350 1351 uint young_regions_count() const { 1352 return _eden.length() + _survivor.length(); 1353 } 1354 1355 uint old_regions_count() const { return _old_set.length(); } 1356 1357 uint humongous_regions_count() const { return _humongous_set.length(); } 1358 1359 #ifdef ASSERT 1360 bool check_young_list_empty(); 1361 #endif 1362 1363 // *** Stuff related to concurrent marking. It's not clear to me that so 1364 // many of these need to be public. 1365 1366 // The functions below are helper functions that a subclass of 1367 // "CollectedHeap" can use in the implementation of its virtual 1368 // functions. 1369 // This performs a concurrent marking of the live objects in a 1370 // bitmap off to the side. 1371 void doConcurrentMark(); 1372 1373 bool isMarkedNext(oop obj) const; 1374 1375 // Determine if an object is dead, given the object and also 1376 // the region to which the object belongs. An object is dead 1377 // iff a) it was not allocated since the last mark, b) it 1378 // is not marked, and c) it is not in an archive region. 1379 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1380 return 1381 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1382 !hr->is_archive(); 1383 } 1384 1385 // This function returns true when an object has been 1386 // around since the previous marking and hasn't yet 1387 // been marked during this marking, and is not in an archive region. 1388 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1389 return 1390 !hr->obj_allocated_since_next_marking(obj) && 1391 !isMarkedNext(obj) && 1392 !hr->is_archive(); 1393 } 1394 1395 // Determine if an object is dead, given only the object itself. 1396 // This will find the region to which the object belongs and 1397 // then call the region version of the same function. 1398 1399 // Added if it is NULL it isn't dead. 1400 1401 inline bool is_obj_dead(const oop obj) const; 1402 1403 inline bool is_obj_ill(const oop obj) const; 1404 1405 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1406 inline bool is_obj_dead_full(const oop obj) const; 1407 1408 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1409 1410 // Refinement 1411 1412 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1413 1414 // Optimized nmethod scanning support routines 1415 1416 // Is an oop scavengeable 1417 virtual bool is_scavengable(oop obj); 1418 1419 // Register the given nmethod with the G1 heap. 1420 virtual void register_nmethod(nmethod* nm); 1421 1422 // Unregister the given nmethod from the G1 heap. 1423 virtual void unregister_nmethod(nmethod* nm); 1424 1425 // Free up superfluous code root memory. 1426 void purge_code_root_memory(); 1427 1428 // Rebuild the strong code root lists for each region 1429 // after a full GC. 1430 void rebuild_strong_code_roots(); 1431 1432 // Partial cleaning used when class unloading is disabled. 1433 // Let the caller choose what structures to clean out: 1434 // - StringTable 1435 // - SymbolTable 1436 // - StringDeduplication structures 1437 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1438 1439 // Complete cleaning used when class unloading is enabled. 1440 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1441 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1442 1443 // Redirty logged cards in the refinement queue. 1444 void redirty_logged_cards(); 1445 // Verification 1446 1447 // Perform any cleanup actions necessary before allowing a verification. 1448 virtual void prepare_for_verify(); 1449 1450 // Perform verification. 1451 1452 // vo == UsePrevMarking -> use "prev" marking information, 1453 // vo == UseNextMarking -> use "next" marking information 1454 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1455 // 1456 // NOTE: Only the "prev" marking information is guaranteed to be 1457 // consistent most of the time, so most calls to this should use 1458 // vo == UsePrevMarking. 1459 // Currently, there is only one case where this is called with 1460 // vo == UseNextMarking, which is to verify the "next" marking 1461 // information at the end of remark. 1462 // Currently there is only one place where this is called with 1463 // vo == UseFullMarking, which is to verify the marking during a 1464 // full GC. 1465 void verify(VerifyOption vo); 1466 1467 // WhiteBox testing support. 1468 virtual bool supports_concurrent_phase_control() const; 1469 virtual const char* const* concurrent_phases() const; 1470 virtual bool request_concurrent_phase(const char* phase); 1471 1472 // The methods below are here for convenience and dispatch the 1473 // appropriate method depending on value of the given VerifyOption 1474 // parameter. The values for that parameter, and their meanings, 1475 // are the same as those above. 1476 1477 bool is_obj_dead_cond(const oop obj, 1478 const HeapRegion* hr, 1479 const VerifyOption vo) const; 1480 1481 bool is_obj_dead_cond(const oop obj, 1482 const VerifyOption vo) const; 1483 1484 G1HeapSummary create_g1_heap_summary(); 1485 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1486 1487 // Printing 1488 private: 1489 void print_heap_regions() const; 1490 void print_regions_on(outputStream* st) const; 1491 1492 public: 1493 virtual void print_on(outputStream* st) const; 1494 virtual void print_extended_on(outputStream* st) const; 1495 virtual void print_on_error(outputStream* st) const; 1496 1497 virtual void print_gc_threads_on(outputStream* st) const; 1498 virtual void gc_threads_do(ThreadClosure* tc) const; 1499 1500 // Override 1501 void print_tracing_info() const; 1502 1503 // The following two methods are helpful for debugging RSet issues. 1504 void print_cset_rsets() PRODUCT_RETURN; 1505 void print_all_rsets() PRODUCT_RETURN; 1506 1507 public: 1508 size_t pending_card_num(); 1509 1510 protected: 1511 size_t _max_heap_capacity; 1512 }; 1513 1514 class G1ParEvacuateFollowersClosure : public VoidClosure { 1515 private: 1516 double _start_term; 1517 double _term_time; 1518 size_t _term_attempts; 1519 1520 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1521 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1522 protected: 1523 G1CollectedHeap* _g1h; 1524 G1ParScanThreadState* _par_scan_state; 1525 RefToScanQueueSet* _queues; 1526 ParallelTaskTerminator* _terminator; 1527 1528 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1529 RefToScanQueueSet* queues() { return _queues; } 1530 ParallelTaskTerminator* terminator() { return _terminator; } 1531 1532 public: 1533 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1534 G1ParScanThreadState* par_scan_state, 1535 RefToScanQueueSet* queues, 1536 ParallelTaskTerminator* terminator) 1537 : _g1h(g1h), _par_scan_state(par_scan_state), 1538 _queues(queues), _terminator(terminator), 1539 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1540 1541 void do_void(); 1542 1543 double term_time() const { return _term_time; } 1544 size_t term_attempts() const { return _term_attempts; } 1545 1546 private: 1547 inline bool offer_termination(); 1548 }; 1549 1550 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP