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