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 OopsInHeapRegionClosure; 65 class G1ParScanThreadState; 66 class G1ParScanThreadStateSet; 67 class G1KlassScanClosure; 68 class G1ParScanThreadState; 69 class ObjectClosure; 70 class SpaceClosure; 71 class CompactibleSpaceClosure; 72 class Space; 73 class G1CollectionSet; 74 class G1CollectorPolicy; 75 class G1Policy; 76 class G1HotCardCache; 77 class G1RemSet; 78 class HeapRegionRemSetIterator; 79 class G1ConcurrentMark; 80 class ConcurrentMarkThread; 81 class ConcurrentG1Refine; 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 95 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 96 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 97 98 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 99 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 100 101 // The G1 STW is alive closure. 102 // An instance is embedded into the G1CH and used as the 103 // (optional) _is_alive_non_header closure in the STW 104 // reference processor. It is also extensively used during 105 // reference processing during STW evacuation pauses. 106 class G1STWIsAliveClosure: public BoolObjectClosure { 107 G1CollectedHeap* _g1; 108 public: 109 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 110 bool do_object_b(oop p); 111 }; 112 113 class RefineCardTableEntryClosure; 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 WorkGang* _workers; 148 G1CollectorPolicy* _collector_policy; 149 150 static size_t _humongous_object_threshold_in_words; 151 152 // The secondary free list which contains regions that have been 153 // freed up during the cleanup process. This will be appended to 154 // the master free list when appropriate. 155 FreeRegionList _secondary_free_list; 156 157 // It keeps track of the old regions. 158 HeapRegionSet _old_set; 159 160 // It keeps track of the humongous regions. 161 HeapRegionSet _humongous_set; 162 163 void eagerly_reclaim_humongous_regions(); 164 // Start a new incremental collection set for the next pause. 165 void start_new_collection_set(); 166 167 // The number of regions we could create by expansion. 168 uint _expansion_regions; 169 170 // The block offset table for the G1 heap. 171 G1BlockOffsetTable* _bot; 172 173 // Tears down the region sets / lists so that they are empty and the 174 // regions on the heap do not belong to a region set / list. The 175 // only exception is the humongous set which we leave unaltered. If 176 // free_list_only is true, it will only tear down the master free 177 // list. It is called before a Full GC (free_list_only == false) or 178 // before heap shrinking (free_list_only == true). 179 void tear_down_region_sets(bool free_list_only); 180 181 // Rebuilds the region sets / lists so that they are repopulated to 182 // reflect the contents of the heap. The only exception is the 183 // humongous set which was not torn down in the first place. If 184 // free_list_only is true, it will only rebuild the master free 185 // list. It is called after a Full GC (free_list_only == false) or 186 // after heap shrinking (free_list_only == true). 187 void rebuild_region_sets(bool free_list_only); 188 189 // Callback for region mapping changed events. 190 G1RegionMappingChangedListener _listener; 191 192 // The sequence of all heap regions in the heap. 193 HeapRegionManager _hrm; 194 195 // Manages all allocations with regions except humongous object allocations. 196 G1Allocator* _allocator; 197 198 // Manages all heap verification. 199 G1HeapVerifier* _verifier; 200 201 // Outside of GC pauses, the number of bytes used in all regions other 202 // than the current allocation region(s). 203 size_t _summary_bytes_used; 204 205 void increase_used(size_t bytes); 206 void decrease_used(size_t bytes); 207 208 void set_used(size_t bytes); 209 210 // Class that handles archive allocation ranges. 211 G1ArchiveAllocator* _archive_allocator; 212 213 // Statistics for each allocation context 214 AllocationContextStats _allocation_context_stats; 215 216 // GC allocation statistics policy for survivors. 217 G1EvacStats _survivor_evac_stats; 218 219 // GC allocation statistics policy for tenured objects. 220 G1EvacStats _old_evac_stats; 221 222 // It specifies whether we should attempt to expand the heap after a 223 // region allocation failure. If heap expansion fails we set this to 224 // false so that we don't re-attempt the heap expansion (it's likely 225 // that subsequent expansion attempts will also fail if one fails). 226 // Currently, it is only consulted during GC and it's reset at the 227 // start of each GC. 228 bool _expand_heap_after_alloc_failure; 229 230 // Helper for monitoring and management support. 231 G1MonitoringSupport* _g1mm; 232 233 // Records whether the region at the given index is (still) a 234 // candidate for eager reclaim. Only valid for humongous start 235 // regions; other regions have unspecified values. Humongous start 236 // regions are initialized at start of collection pause, with 237 // candidates removed from the set as they are found reachable from 238 // roots or the young generation. 239 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 240 protected: 241 bool default_value() const { return false; } 242 public: 243 void clear() { G1BiasedMappedArray<bool>::clear(); } 244 void set_candidate(uint region, bool value) { 245 set_by_index(region, value); 246 } 247 bool is_candidate(uint region) { 248 return get_by_index(region); 249 } 250 }; 251 252 HumongousReclaimCandidates _humongous_reclaim_candidates; 253 // Stores whether during humongous object registration we found candidate regions. 254 // If not, we can skip a few steps. 255 bool _has_humongous_reclaim_candidates; 256 257 volatile uint _gc_time_stamp; 258 259 G1HRPrinter _hr_printer; 260 261 // It decides whether an explicit GC should start a concurrent cycle 262 // instead of doing a STW GC. Currently, a concurrent cycle is 263 // explicitly started if: 264 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 265 // (b) cause == _g1_humongous_allocation 266 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 267 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 268 // (e) cause == _update_allocation_context_stats_inc 269 // (f) cause == _wb_conc_mark 270 bool should_do_concurrent_full_gc(GCCause::Cause cause); 271 272 // indicates whether we are in young or mixed GC mode 273 G1CollectorState _collector_state; 274 275 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 276 // concurrent cycles) we have started. 277 volatile uint _old_marking_cycles_started; 278 279 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 280 // concurrent cycles) we have completed. 281 volatile uint _old_marking_cycles_completed; 282 283 // This is a non-product method that is helpful for testing. It is 284 // called at the end of a GC and artificially expands the heap by 285 // allocating a number of dead regions. This way we can induce very 286 // frequent marking cycles and stress the cleanup / concurrent 287 // cleanup code more (as all the regions that will be allocated by 288 // this method will be found dead by the marking cycle). 289 void allocate_dummy_regions() PRODUCT_RETURN; 290 291 // Clear RSets after a compaction. It also resets the GC time stamps. 292 void clear_rsets_post_compaction(); 293 294 // If the HR printer is active, dump the state of the regions in the 295 // heap after a compaction. 296 void print_hrm_post_compaction(); 297 298 // Create a memory mapper for auxiliary data structures of the given size and 299 // translation factor. 300 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 301 size_t size, 302 size_t translation_factor); 303 304 static G1Policy* create_g1_policy(); 305 306 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 307 308 void process_weak_jni_handles(); 309 310 // These are macros so that, if the assert fires, we get the correct 311 // line number, file, etc. 312 313 #define heap_locking_asserts_params(_extra_message_) \ 314 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 315 (_extra_message_), \ 316 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 317 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 318 BOOL_TO_STR(Thread::current()->is_VM_thread()) 319 320 #define assert_heap_locked() \ 321 do { \ 322 assert(Heap_lock->owned_by_self(), \ 323 heap_locking_asserts_params("should be holding the Heap_lock")); \ 324 } while (0) 325 326 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 327 do { \ 328 assert(Heap_lock->owned_by_self() || \ 329 (SafepointSynchronize::is_at_safepoint() && \ 330 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 331 heap_locking_asserts_params("should be holding the Heap_lock or " \ 332 "should be at a safepoint")); \ 333 } while (0) 334 335 #define assert_heap_locked_and_not_at_safepoint() \ 336 do { \ 337 assert(Heap_lock->owned_by_self() && \ 338 !SafepointSynchronize::is_at_safepoint(), \ 339 heap_locking_asserts_params("should be holding the Heap_lock and " \ 340 "should not be at a safepoint")); \ 341 } while (0) 342 343 #define assert_heap_not_locked() \ 344 do { \ 345 assert(!Heap_lock->owned_by_self(), \ 346 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 347 } while (0) 348 349 #define assert_heap_not_locked_and_not_at_safepoint() \ 350 do { \ 351 assert(!Heap_lock->owned_by_self() && \ 352 !SafepointSynchronize::is_at_safepoint(), \ 353 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 354 "should not be at a safepoint")); \ 355 } while (0) 356 357 #define assert_at_safepoint(_should_be_vm_thread_) \ 358 do { \ 359 assert(SafepointSynchronize::is_at_safepoint() && \ 360 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 361 heap_locking_asserts_params("should be at a safepoint")); \ 362 } while (0) 363 364 #define assert_not_at_safepoint() \ 365 do { \ 366 assert(!SafepointSynchronize::is_at_safepoint(), \ 367 heap_locking_asserts_params("should not be at a safepoint")); \ 368 } while (0) 369 370 protected: 371 372 // The young region list. 373 G1EdenRegions _eden; 374 G1SurvivorRegions _survivor; 375 376 // The current policy object for the collector. 377 G1Policy* _g1_policy; 378 G1HeapSizingPolicy* _heap_sizing_policy; 379 380 G1CollectionSet _collection_set; 381 382 // This is the second level of trying to allocate a new region. If 383 // new_region() didn't find a region on the free_list, this call will 384 // check whether there's anything available on the 385 // secondary_free_list and/or wait for more regions to appear on 386 // that list, if _free_regions_coming is set. 387 HeapRegion* new_region_try_secondary_free_list(bool is_old); 388 389 // Try to allocate a single non-humongous HeapRegion sufficient for 390 // an allocation of the given word_size. If do_expand is true, 391 // attempt to expand the heap if necessary to satisfy the allocation 392 // request. If the region is to be used as an old region or for a 393 // humongous object, set is_old to true. If not, to false. 394 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 395 396 // Initialize a contiguous set of free regions of length num_regions 397 // and starting at index first so that they appear as a single 398 // humongous region. 399 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 400 uint num_regions, 401 size_t word_size, 402 AllocationContext_t context); 403 404 // Attempt to allocate a humongous object of the given size. Return 405 // NULL if unsuccessful. 406 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 407 408 // The following two methods, allocate_new_tlab() and 409 // mem_allocate(), are the two main entry points from the runtime 410 // into the G1's allocation routines. They have the following 411 // assumptions: 412 // 413 // * They should both be called outside safepoints. 414 // 415 // * They should both be called without holding the Heap_lock. 416 // 417 // * All allocation requests for new TLABs should go to 418 // allocate_new_tlab(). 419 // 420 // * All non-TLAB allocation requests should go to mem_allocate(). 421 // 422 // * If either call cannot satisfy the allocation request using the 423 // current allocating region, they will try to get a new one. If 424 // this fails, they will attempt to do an evacuation pause and 425 // retry the allocation. 426 // 427 // * If all allocation attempts fail, even after trying to schedule 428 // an evacuation pause, allocate_new_tlab() will return NULL, 429 // whereas mem_allocate() will attempt a heap expansion and/or 430 // schedule a Full GC. 431 // 432 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 433 // should never be called with word_size being humongous. All 434 // humongous allocation requests should go to mem_allocate() which 435 // will satisfy them with a special path. 436 437 virtual HeapWord* allocate_new_tlab(size_t word_size); 438 439 virtual HeapWord* mem_allocate(size_t word_size, 440 bool* gc_overhead_limit_was_exceeded); 441 442 // The following three methods take a gc_count_before_ret 443 // parameter which is used to return the GC count if the method 444 // returns NULL. Given that we are required to read the GC count 445 // while holding the Heap_lock, and these paths will take the 446 // Heap_lock at some point, it's easier to get them to read the GC 447 // count while holding the Heap_lock before they return NULL instead 448 // of the caller (namely: mem_allocate()) having to also take the 449 // Heap_lock just to read the GC count. 450 451 // First-level mutator allocation attempt: try to allocate out of 452 // the mutator alloc region without taking the Heap_lock. This 453 // should only be used for non-humongous allocations. 454 inline HeapWord* attempt_allocation(size_t word_size, 455 uint* gc_count_before_ret, 456 uint* gclocker_retry_count_ret); 457 458 // Second-level mutator allocation attempt: take the Heap_lock and 459 // retry the allocation attempt, potentially scheduling a GC 460 // pause. This should only be used for non-humongous allocations. 461 HeapWord* attempt_allocation_slow(size_t word_size, 462 AllocationContext_t context, 463 uint* gc_count_before_ret, 464 uint* gclocker_retry_count_ret); 465 466 // Takes the Heap_lock and attempts a humongous allocation. It can 467 // potentially schedule a GC pause. 468 HeapWord* attempt_allocation_humongous(size_t word_size, 469 uint* gc_count_before_ret, 470 uint* gclocker_retry_count_ret); 471 472 // Allocation attempt that should be called during safepoints (e.g., 473 // at the end of a successful GC). expect_null_mutator_alloc_region 474 // specifies whether the mutator alloc region is expected to be NULL 475 // or not. 476 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 477 AllocationContext_t context, 478 bool expect_null_mutator_alloc_region); 479 480 // These methods are the "callbacks" from the G1AllocRegion class. 481 482 // For mutator alloc regions. 483 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 484 void retire_mutator_alloc_region(HeapRegion* alloc_region, 485 size_t allocated_bytes); 486 487 // For GC alloc regions. 488 bool has_more_regions(InCSetState dest); 489 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 490 void retire_gc_alloc_region(HeapRegion* alloc_region, 491 size_t allocated_bytes, InCSetState dest); 492 493 // - if explicit_gc is true, the GC is for a System.gc() etc, 494 // otherwise it's for a failed allocation. 495 // - if clear_all_soft_refs is true, all soft references should be 496 // cleared during the GC. 497 // - it returns false if it is unable to do the collection due to the 498 // GC locker being active, true otherwise. 499 bool do_full_collection(bool explicit_gc, 500 bool clear_all_soft_refs); 501 502 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 503 virtual void do_full_collection(bool clear_all_soft_refs); 504 505 // Resize the heap if necessary after a full collection. 506 void resize_if_necessary_after_full_collection(); 507 508 // Callback from VM_G1CollectForAllocation operation. 509 // This function does everything necessary/possible to satisfy a 510 // failed allocation request (including collection, expansion, etc.) 511 HeapWord* satisfy_failed_allocation(size_t word_size, 512 AllocationContext_t context, 513 bool* succeeded); 514 private: 515 // Internal helpers used during full GC to split it up to 516 // increase readability. 517 void do_full_collection_inner(G1FullGCScope* scope); 518 void abort_concurrent_cycle(); 519 void verify_before_full_collection(bool explicit_gc); 520 void prepare_heap_for_full_collection(); 521 void prepare_heap_for_mutators(); 522 void abort_refinement(); 523 void verify_after_full_collection(); 524 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 525 526 // Helper method for satisfy_failed_allocation() 527 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 528 AllocationContext_t context, 529 bool do_gc, 530 bool clear_all_soft_refs, 531 bool expect_null_mutator_alloc_region, 532 bool* gc_succeeded); 533 534 protected: 535 // Attempting to expand the heap sufficiently 536 // to support an allocation of the given "word_size". If 537 // successful, perform the allocation and return the address of the 538 // allocated block, or else "NULL". 539 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 540 541 // Preserve any referents discovered by concurrent marking that have not yet been 542 // copied by the STW pause. 543 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 544 // Process any reference objects discovered during 545 // an incremental evacuation pause. 546 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 547 548 // Enqueue any remaining discovered references 549 // after processing. 550 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 551 552 // Merges the information gathered on a per-thread basis for all worker threads 553 // during GC into global variables. 554 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 555 public: 556 WorkGang* workers() const { return _workers; } 557 558 G1Allocator* allocator() { 559 return _allocator; 560 } 561 562 G1HeapVerifier* verifier() { 563 return _verifier; 564 } 565 566 G1MonitoringSupport* g1mm() { 567 assert(_g1mm != NULL, "should have been initialized"); 568 return _g1mm; 569 } 570 571 // Expand the garbage-first heap by at least the given size (in bytes!). 572 // Returns true if the heap was expanded by the requested amount; 573 // false otherwise. 574 // (Rounds up to a HeapRegion boundary.) 575 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 576 577 // Returns the PLAB statistics for a given destination. 578 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 579 580 // Determines PLAB size for a given destination. 581 inline size_t desired_plab_sz(InCSetState dest); 582 583 inline AllocationContextStats& allocation_context_stats(); 584 585 // Do anything common to GC's. 586 void gc_prologue(bool full); 587 void gc_epilogue(bool full); 588 589 // Modify the reclaim candidate set and test for presence. 590 // These are only valid for starts_humongous regions. 591 inline void set_humongous_reclaim_candidate(uint region, bool value); 592 inline bool is_humongous_reclaim_candidate(uint region); 593 594 // Remove from the reclaim candidate set. Also remove from the 595 // collection set so that later encounters avoid the slow path. 596 inline void set_humongous_is_live(oop obj); 597 598 // Register the given region to be part of the collection set. 599 inline void register_humongous_region_with_cset(uint index); 600 // Register regions with humongous objects (actually on the start region) in 601 // the in_cset_fast_test table. 602 void register_humongous_regions_with_cset(); 603 // We register a region with the fast "in collection set" test. We 604 // simply set to true the array slot corresponding to this region. 605 void register_young_region_with_cset(HeapRegion* r) { 606 _in_cset_fast_test.set_in_young(r->hrm_index()); 607 } 608 void register_old_region_with_cset(HeapRegion* r) { 609 _in_cset_fast_test.set_in_old(r->hrm_index()); 610 } 611 inline void register_ext_region_with_cset(HeapRegion* r) { 612 _in_cset_fast_test.set_ext(r->hrm_index()); 613 } 614 void clear_in_cset(const HeapRegion* hr) { 615 _in_cset_fast_test.clear(hr); 616 } 617 618 void clear_cset_fast_test() { 619 _in_cset_fast_test.clear(); 620 } 621 622 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 623 624 // This is called at the start of either a concurrent cycle or a Full 625 // GC to update the number of old marking cycles started. 626 void increment_old_marking_cycles_started(); 627 628 // This is called at the end of either a concurrent cycle or a Full 629 // GC to update the number of old marking cycles completed. Those two 630 // can happen in a nested fashion, i.e., we start a concurrent 631 // cycle, a Full GC happens half-way through it which ends first, 632 // and then the cycle notices that a Full GC happened and ends 633 // too. The concurrent parameter is a boolean to help us do a bit 634 // tighter consistency checking in the method. If concurrent is 635 // false, the caller is the inner caller in the nesting (i.e., the 636 // Full GC). If concurrent is true, the caller is the outer caller 637 // in this nesting (i.e., the concurrent cycle). Further nesting is 638 // not currently supported. The end of this call also notifies 639 // the FullGCCount_lock in case a Java thread is waiting for a full 640 // GC to happen (e.g., it called System.gc() with 641 // +ExplicitGCInvokesConcurrent). 642 void increment_old_marking_cycles_completed(bool concurrent); 643 644 uint old_marking_cycles_completed() { 645 return _old_marking_cycles_completed; 646 } 647 648 G1HRPrinter* hr_printer() { return &_hr_printer; } 649 650 // Allocates a new heap region instance. 651 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 652 653 // Allocate the highest free region in the reserved heap. This will commit 654 // regions as necessary. 655 HeapRegion* alloc_highest_free_region(); 656 657 // Frees a non-humongous region by initializing its contents and 658 // adding it to the free list that's passed as a parameter (this is 659 // usually a local list which will be appended to the master free 660 // list later). The used bytes of freed regions are accumulated in 661 // pre_used. If skip_remset is true, the region's RSet will not be freed 662 // up. If skip_hot_card_cache is true, the region's hot card cache will not 663 // be freed up. The assumption is that this will be done later. 664 // The locked parameter indicates if the caller has already taken 665 // care of proper synchronization. This may allow some optimizations. 666 void free_region(HeapRegion* hr, 667 FreeRegionList* free_list, 668 bool skip_remset, 669 bool skip_hot_card_cache = false, 670 bool locked = false); 671 672 // It dirties the cards that cover the block so that the post 673 // write barrier never queues anything when updating objects on this 674 // block. It is assumed (and in fact we assert) that the block 675 // belongs to a young region. 676 inline void dirty_young_block(HeapWord* start, size_t word_size); 677 678 // Frees a humongous region by collapsing it into individual regions 679 // and calling free_region() for each of them. The freed regions 680 // will be added to the free list that's passed as a parameter (this 681 // is usually a local list which will be appended to the master free 682 // list later). The used bytes of freed regions are accumulated in 683 // pre_used. If skip_remset is true, the region's RSet will not be freed 684 // up. The assumption is that this will be done later. 685 void free_humongous_region(HeapRegion* hr, 686 FreeRegionList* free_list, 687 bool skip_remset); 688 689 // Facility for allocating in 'archive' regions in high heap memory and 690 // recording the allocated ranges. These should all be called from the 691 // VM thread at safepoints, without the heap lock held. They can be used 692 // to create and archive a set of heap regions which can be mapped at the 693 // same fixed addresses in a subsequent JVM invocation. 694 void begin_archive_alloc_range(); 695 696 // Check if the requested size would be too large for an archive allocation. 697 bool is_archive_alloc_too_large(size_t word_size); 698 699 // Allocate memory of the requested size from the archive region. This will 700 // return NULL if the size is too large or if no memory is available. It 701 // does not trigger a garbage collection. 702 HeapWord* archive_mem_allocate(size_t word_size); 703 704 // Optionally aligns the end address and returns the allocated ranges in 705 // an array of MemRegions in order of ascending addresses. 706 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 707 size_t end_alignment_in_bytes = 0); 708 709 // Facility for allocating a fixed range within the heap and marking 710 // the containing regions as 'archive'. For use at JVM init time, when the 711 // caller may mmap archived heap data at the specified range(s). 712 // Verify that the MemRegions specified in the argument array are within the 713 // reserved heap. 714 bool check_archive_addresses(MemRegion* range, size_t count); 715 716 // Commit the appropriate G1 regions containing the specified MemRegions 717 // and mark them as 'archive' regions. The regions in the array must be 718 // non-overlapping and in order of ascending address. 719 bool alloc_archive_regions(MemRegion* range, size_t count); 720 721 // Insert any required filler objects in the G1 regions around the specified 722 // ranges to make the regions parseable. This must be called after 723 // alloc_archive_regions, and after class loading has occurred. 724 void fill_archive_regions(MemRegion* range, size_t count); 725 726 // For each of the specified MemRegions, uncommit the containing G1 regions 727 // which had been allocated by alloc_archive_regions. This should be called 728 // rather than fill_archive_regions at JVM init time if the archive file 729 // mapping failed, with the same non-overlapping and sorted MemRegion array. 730 void dealloc_archive_regions(MemRegion* range, size_t count); 731 732 protected: 733 734 // Shrink the garbage-first heap by at most the given size (in bytes!). 735 // (Rounds down to a HeapRegion boundary.) 736 virtual void shrink(size_t expand_bytes); 737 void shrink_helper(size_t expand_bytes); 738 739 #if TASKQUEUE_STATS 740 static void print_taskqueue_stats_hdr(outputStream* const st); 741 void print_taskqueue_stats() const; 742 void reset_taskqueue_stats(); 743 #endif // TASKQUEUE_STATS 744 745 // Schedule the VM operation that will do an evacuation pause to 746 // satisfy an allocation request of word_size. *succeeded will 747 // return whether the VM operation was successful (it did do an 748 // evacuation pause) or not (another thread beat us to it or the GC 749 // locker was active). Given that we should not be holding the 750 // Heap_lock when we enter this method, we will pass the 751 // gc_count_before (i.e., total_collections()) as a parameter since 752 // it has to be read while holding the Heap_lock. Currently, both 753 // methods that call do_collection_pause() release the Heap_lock 754 // before the call, so it's easy to read gc_count_before just before. 755 HeapWord* do_collection_pause(size_t word_size, 756 uint gc_count_before, 757 bool* succeeded, 758 GCCause::Cause gc_cause); 759 760 void wait_for_root_region_scanning(); 761 762 // The guts of the incremental collection pause, executed by the vm 763 // thread. It returns false if it is unable to do the collection due 764 // to the GC locker being active, true otherwise 765 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 766 767 // Actually do the work of evacuating the collection set. 768 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 769 770 void pre_evacuate_collection_set(); 771 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 772 773 // Print the header for the per-thread termination statistics. 774 static void print_termination_stats_hdr(); 775 // Print actual per-thread termination statistics. 776 void print_termination_stats(uint worker_id, 777 double elapsed_ms, 778 double strong_roots_ms, 779 double term_ms, 780 size_t term_attempts, 781 size_t alloc_buffer_waste, 782 size_t undo_waste) const; 783 // Update object copying statistics. 784 void record_obj_copy_mem_stats(); 785 786 // The hot card cache for remembered set insertion optimization. 787 G1HotCardCache* _hot_card_cache; 788 789 // The g1 remembered set of the heap. 790 G1RemSet* _g1_rem_set; 791 792 // A set of cards that cover the objects for which the Rsets should be updated 793 // concurrently after the collection. 794 DirtyCardQueueSet _dirty_card_queue_set; 795 796 // The closure used to refine a single card. 797 RefineCardTableEntryClosure* _refine_cte_cl; 798 799 // After a collection pause, convert the regions in the collection set into free 800 // regions. 801 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 802 803 // Abandon the current collection set without recording policy 804 // statistics or updating free lists. 805 void abandon_collection_set(G1CollectionSet* collection_set); 806 807 // The concurrent marker (and the thread it runs in.) 808 G1ConcurrentMark* _cm; 809 ConcurrentMarkThread* _cmThread; 810 811 // The concurrent refiner. 812 ConcurrentG1Refine* _cg1r; 813 814 // The parallel task queues 815 RefToScanQueueSet *_task_queues; 816 817 // True iff a evacuation has failed in the current collection. 818 bool _evacuation_failed; 819 820 EvacuationFailedInfo* _evacuation_failed_info_array; 821 822 // Failed evacuations cause some logical from-space objects to have 823 // forwarding pointers to themselves. Reset them. 824 void remove_self_forwarding_pointers(); 825 826 // Restore the objects in the regions in the collection set after an 827 // evacuation failure. 828 void restore_after_evac_failure(); 829 830 PreservedMarksSet _preserved_marks_set; 831 832 // Preserve the mark of "obj", if necessary, in preparation for its mark 833 // word being overwritten with a self-forwarding-pointer. 834 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 835 836 #ifndef PRODUCT 837 // Support for forcing evacuation failures. Analogous to 838 // PromotionFailureALot for the other collectors. 839 840 // Records whether G1EvacuationFailureALot should be in effect 841 // for the current GC 842 bool _evacuation_failure_alot_for_current_gc; 843 844 // Used to record the GC number for interval checking when 845 // determining whether G1EvaucationFailureALot is in effect 846 // for the current GC. 847 size_t _evacuation_failure_alot_gc_number; 848 849 // Count of the number of evacuations between failures. 850 volatile size_t _evacuation_failure_alot_count; 851 852 // Set whether G1EvacuationFailureALot should be in effect 853 // for the current GC (based upon the type of GC and which 854 // command line flags are set); 855 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 856 bool during_initial_mark, 857 bool during_marking); 858 859 inline void set_evacuation_failure_alot_for_current_gc(); 860 861 // Return true if it's time to cause an evacuation failure. 862 inline bool evacuation_should_fail(); 863 864 // Reset the G1EvacuationFailureALot counters. Should be called at 865 // the end of an evacuation pause in which an evacuation failure occurred. 866 inline void reset_evacuation_should_fail(); 867 #endif // !PRODUCT 868 869 // ("Weak") Reference processing support. 870 // 871 // G1 has 2 instances of the reference processor class. One 872 // (_ref_processor_cm) handles reference object discovery 873 // and subsequent processing during concurrent marking cycles. 874 // 875 // The other (_ref_processor_stw) handles reference object 876 // discovery and processing during full GCs and incremental 877 // evacuation pauses. 878 // 879 // During an incremental pause, reference discovery will be 880 // temporarily disabled for _ref_processor_cm and will be 881 // enabled for _ref_processor_stw. At the end of the evacuation 882 // pause references discovered by _ref_processor_stw will be 883 // processed and discovery will be disabled. The previous 884 // setting for reference object discovery for _ref_processor_cm 885 // will be re-instated. 886 // 887 // At the start of marking: 888 // * Discovery by the CM ref processor is verified to be inactive 889 // and it's discovered lists are empty. 890 // * Discovery by the CM ref processor is then enabled. 891 // 892 // At the end of marking: 893 // * Any references on the CM ref processor's discovered 894 // lists are processed (possibly MT). 895 // 896 // At the start of full GC we: 897 // * Disable discovery by the CM ref processor and 898 // empty CM ref processor's discovered lists 899 // (without processing any entries). 900 // * Verify that the STW ref processor is inactive and it's 901 // discovered lists are empty. 902 // * Temporarily set STW ref processor discovery as single threaded. 903 // * Temporarily clear the STW ref processor's _is_alive_non_header 904 // field. 905 // * Finally enable discovery by the STW ref processor. 906 // 907 // The STW ref processor is used to record any discovered 908 // references during the full GC. 909 // 910 // At the end of a full GC we: 911 // * Enqueue any reference objects discovered by the STW ref processor 912 // that have non-live referents. This has the side-effect of 913 // making the STW ref processor inactive by disabling discovery. 914 // * Verify that the CM ref processor is still inactive 915 // and no references have been placed on it's discovered 916 // lists (also checked as a precondition during initial marking). 917 918 // The (stw) reference processor... 919 ReferenceProcessor* _ref_processor_stw; 920 921 STWGCTimer* _gc_timer_stw; 922 923 G1NewTracer* _gc_tracer_stw; 924 925 // During reference object discovery, the _is_alive_non_header 926 // closure (if non-null) is applied to the referent object to 927 // determine whether the referent is live. If so then the 928 // reference object does not need to be 'discovered' and can 929 // be treated as a regular oop. This has the benefit of reducing 930 // the number of 'discovered' reference objects that need to 931 // be processed. 932 // 933 // Instance of the is_alive closure for embedding into the 934 // STW reference processor as the _is_alive_non_header field. 935 // Supplying a value for the _is_alive_non_header field is 936 // optional but doing so prevents unnecessary additions to 937 // the discovered lists during reference discovery. 938 G1STWIsAliveClosure _is_alive_closure_stw; 939 940 // The (concurrent marking) reference processor... 941 ReferenceProcessor* _ref_processor_cm; 942 943 // Instance of the concurrent mark is_alive closure for embedding 944 // into the Concurrent Marking reference processor as the 945 // _is_alive_non_header field. Supplying a value for the 946 // _is_alive_non_header field is optional but doing so prevents 947 // unnecessary additions to the discovered lists during reference 948 // discovery. 949 G1CMIsAliveClosure _is_alive_closure_cm; 950 951 volatile bool _free_regions_coming; 952 953 public: 954 955 void set_refine_cte_cl_concurrency(bool concurrent); 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 // 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(); 975 976 // Return the (conservative) maximum heap alignment for any G1 heap 977 static size_t conservative_max_heap_alignment(); 978 979 // Does operations required after initialization has been done. 980 void post_initialize(); 981 982 // Initialize weak reference processing. 983 void ref_processing_init(); 984 985 virtual Name kind() const { 986 return CollectedHeap::G1CollectedHeap; 987 } 988 989 virtual const char* name() const { 990 return "G1"; 991 } 992 993 const G1CollectorState* collector_state() const { return &_collector_state; } 994 G1CollectorState* collector_state() { return &_collector_state; } 995 996 // The current policy object for the collector. 997 G1Policy* g1_policy() const { return _g1_policy; } 998 999 const G1CollectionSet* collection_set() const { return &_collection_set; } 1000 G1CollectionSet* collection_set() { return &_collection_set; } 1001 1002 virtual CollectorPolicy* collector_policy() const; 1003 1004 // Adaptive size policy. No such thing for g1. 1005 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1006 1007 // The rem set and barrier set. 1008 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1009 1010 // Try to minimize the remembered set. 1011 void scrub_rem_set(); 1012 1013 uint get_gc_time_stamp() { 1014 return _gc_time_stamp; 1015 } 1016 1017 inline void reset_gc_time_stamp(); 1018 1019 void check_gc_time_stamps() PRODUCT_RETURN; 1020 1021 inline void increment_gc_time_stamp(); 1022 1023 // Reset the given region's GC timestamp. If it's starts humongous, 1024 // also reset the GC timestamp of its corresponding 1025 // continues humongous regions too. 1026 void reset_gc_time_stamps(HeapRegion* hr); 1027 1028 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1029 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1030 1031 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1032 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1033 1034 // The shared block offset table array. 1035 G1BlockOffsetTable* bot() const { return _bot; } 1036 1037 // Reference Processing accessors 1038 1039 // The STW reference processor.... 1040 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1041 1042 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1043 1044 // The Concurrent Marking reference processor... 1045 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1046 1047 virtual size_t capacity() const; 1048 virtual size_t used() const; 1049 // This should be called when we're not holding the heap lock. The 1050 // result might be a bit inaccurate. 1051 size_t used_unlocked() const; 1052 size_t recalculate_used() const; 1053 1054 // These virtual functions do the actual allocation. 1055 // Some heaps may offer a contiguous region for shared non-blocking 1056 // allocation, via inlined code (by exporting the address of the top and 1057 // end fields defining the extent of the contiguous allocation region.) 1058 // But G1CollectedHeap doesn't yet support this. 1059 1060 virtual bool is_maximal_no_gc() const { 1061 return _hrm.available() == 0; 1062 } 1063 1064 // The current number of regions in the heap. 1065 uint num_regions() const { return _hrm.length(); } 1066 1067 // The max number of regions in the heap. 1068 uint max_regions() const { return _hrm.max_length(); } 1069 1070 // The number of regions that are completely free. 1071 uint num_free_regions() const { return _hrm.num_free_regions(); } 1072 1073 MemoryUsage get_auxiliary_data_memory_usage() const { 1074 return _hrm.get_auxiliary_data_memory_usage(); 1075 } 1076 1077 // The number of regions that are not completely free. 1078 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1079 1080 #ifdef ASSERT 1081 bool is_on_master_free_list(HeapRegion* hr) { 1082 return _hrm.is_free(hr); 1083 } 1084 #endif // ASSERT 1085 1086 // Wrapper for the region list operations that can be called from 1087 // methods outside this class. 1088 1089 void secondary_free_list_add(FreeRegionList* list) { 1090 _secondary_free_list.add_ordered(list); 1091 } 1092 1093 void append_secondary_free_list() { 1094 _hrm.insert_list_into_free_list(&_secondary_free_list); 1095 } 1096 1097 void append_secondary_free_list_if_not_empty_with_lock() { 1098 // If the secondary free list looks empty there's no reason to 1099 // take the lock and then try to append it. 1100 if (!_secondary_free_list.is_empty()) { 1101 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1102 append_secondary_free_list(); 1103 } 1104 } 1105 1106 inline void old_set_add(HeapRegion* hr); 1107 inline void old_set_remove(HeapRegion* hr); 1108 1109 size_t non_young_capacity_bytes() { 1110 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1111 } 1112 1113 void set_free_regions_coming(); 1114 void reset_free_regions_coming(); 1115 bool free_regions_coming() { return _free_regions_coming; } 1116 void wait_while_free_regions_coming(); 1117 1118 // Determine whether the given region is one that we are using as an 1119 // old GC alloc region. 1120 bool is_old_gc_alloc_region(HeapRegion* hr); 1121 1122 // Perform a collection of the heap; intended for use in implementing 1123 // "System.gc". This probably implies as full a collection as the 1124 // "CollectedHeap" supports. 1125 virtual void collect(GCCause::Cause cause); 1126 1127 virtual bool copy_allocation_context_stats(const jint* contexts, 1128 jlong* totals, 1129 jbyte* accuracy, 1130 jint len); 1131 1132 // True iff an evacuation has failed in the most-recent collection. 1133 bool evacuation_failed() { return _evacuation_failed; } 1134 1135 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1136 void prepend_to_freelist(FreeRegionList* list); 1137 void decrement_summary_bytes(size_t bytes); 1138 1139 virtual bool is_in(const void* p) const; 1140 #ifdef ASSERT 1141 // Returns whether p is in one of the available areas of the heap. Slow but 1142 // extensive version. 1143 bool is_in_exact(const void* p) const; 1144 #endif 1145 1146 // Return "TRUE" iff the given object address is within the collection 1147 // set. Assumes that the reference points into the heap. 1148 inline bool is_in_cset(const HeapRegion *hr); 1149 inline bool is_in_cset(oop obj); 1150 1151 inline bool is_in_cset_or_humongous(const oop obj); 1152 1153 private: 1154 // This array is used for a quick test on whether a reference points into 1155 // the collection set or not. Each of the array's elements denotes whether the 1156 // corresponding region is in the collection set or not. 1157 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1158 1159 public: 1160 1161 inline InCSetState in_cset_state(const oop obj); 1162 1163 // Return "TRUE" iff the given object address is in the reserved 1164 // region of g1. 1165 bool is_in_g1_reserved(const void* p) const { 1166 return _hrm.reserved().contains(p); 1167 } 1168 1169 // Returns a MemRegion that corresponds to the space that has been 1170 // reserved for the heap 1171 MemRegion g1_reserved() const { 1172 return _hrm.reserved(); 1173 } 1174 1175 virtual bool is_in_closed_subset(const void* p) const; 1176 1177 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1178 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1179 } 1180 1181 // Iteration functions. 1182 1183 // Iterate over all objects, calling "cl.do_object" on each. 1184 virtual void object_iterate(ObjectClosure* cl); 1185 1186 virtual void safe_object_iterate(ObjectClosure* cl) { 1187 object_iterate(cl); 1188 } 1189 1190 // Iterate over heap regions, in address order, terminating the 1191 // iteration early if the "doHeapRegion" method returns "true". 1192 void heap_region_iterate(HeapRegionClosure* blk) const; 1193 1194 // Return the region with the given index. It assumes the index is valid. 1195 inline HeapRegion* region_at(uint index) const; 1196 1197 // Return the next region (by index) that is part of the same 1198 // humongous object that hr is part of. 1199 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1200 1201 // Calculate the region index of the given address. Given address must be 1202 // within the heap. 1203 inline uint addr_to_region(HeapWord* addr) const; 1204 1205 inline HeapWord* bottom_addr_for_region(uint index) const; 1206 1207 // Iterate over the heap regions in parallel. Assumes that this will be called 1208 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1209 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1210 // to each of the regions, by attempting to claim the region using the 1211 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1212 // region. The concurrent argument should be set to true if iteration is 1213 // performed concurrently, during which no assumptions are made for consistent 1214 // attributes of the heap regions (as they might be modified while iterating). 1215 void heap_region_par_iterate(HeapRegionClosure* cl, 1216 uint worker_id, 1217 HeapRegionClaimer* hrclaimer, 1218 bool concurrent = false) 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 virtual bool is_scavengable(const void* addr); 1292 1293 // We don't need barriers for initializing stores to objects 1294 // in the young gen: for the SATB pre-barrier, there is no 1295 // pre-value that needs to be remembered; for the remembered-set 1296 // update logging post-barrier, we don't maintain remembered set 1297 // information for young gen objects. 1298 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1299 1300 // Returns "true" iff the given word_size is "very large". 1301 static bool is_humongous(size_t word_size) { 1302 // Note this has to be strictly greater-than as the TLABs 1303 // are capped at the humongous threshold and we want to 1304 // ensure that we don't try to allocate a TLAB as 1305 // humongous and that we don't allocate a humongous 1306 // object in a TLAB. 1307 return word_size > _humongous_object_threshold_in_words; 1308 } 1309 1310 // Returns the humongous threshold for a specific region size 1311 static size_t humongous_threshold_for(size_t region_size) { 1312 return (region_size / 2); 1313 } 1314 1315 // Returns the number of regions the humongous object of the given word size 1316 // requires. 1317 static size_t humongous_obj_size_in_regions(size_t word_size); 1318 1319 // Print the maximum heap capacity. 1320 virtual size_t max_capacity() const; 1321 1322 virtual jlong millis_since_last_gc(); 1323 1324 1325 // Convenience function to be used in situations where the heap type can be 1326 // asserted to be this type. 1327 static G1CollectedHeap* heap(); 1328 1329 void set_region_short_lived_locked(HeapRegion* hr); 1330 // add appropriate methods for any other surv rate groups 1331 1332 const G1SurvivorRegions* survivor() const { return &_survivor; } 1333 1334 uint survivor_regions_count() const { 1335 return _survivor.length(); 1336 } 1337 1338 uint eden_regions_count() const { 1339 return _eden.length(); 1340 } 1341 1342 uint young_regions_count() const { 1343 return _eden.length() + _survivor.length(); 1344 } 1345 1346 uint old_regions_count() const { return _old_set.length(); } 1347 1348 uint humongous_regions_count() const { return _humongous_set.length(); } 1349 1350 #ifdef ASSERT 1351 bool check_young_list_empty(); 1352 #endif 1353 1354 // *** Stuff related to concurrent marking. It's not clear to me that so 1355 // many of these need to be public. 1356 1357 // The functions below are helper functions that a subclass of 1358 // "CollectedHeap" can use in the implementation of its virtual 1359 // functions. 1360 // This performs a concurrent marking of the live objects in a 1361 // bitmap off to the side. 1362 void doConcurrentMark(); 1363 1364 bool isMarkedNext(oop obj) const; 1365 1366 // Determine if an object is dead, given the object and also 1367 // the region to which the object belongs. An object is dead 1368 // iff a) it was not allocated since the last mark, b) it 1369 // is not marked, and c) it is not in an archive region. 1370 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1371 return 1372 hr->is_obj_dead(obj, _cm->prevMarkBitMap()) && 1373 !hr->is_archive(); 1374 } 1375 1376 // This function returns true when an object has been 1377 // around since the previous marking and hasn't yet 1378 // been marked during this marking, and is not in an archive region. 1379 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1380 return 1381 !hr->obj_allocated_since_next_marking(obj) && 1382 !isMarkedNext(obj) && 1383 !hr->is_archive(); 1384 } 1385 1386 // Determine if an object is dead, given only the object itself. 1387 // This will find the region to which the object belongs and 1388 // then call the region version of the same function. 1389 1390 // Added if it is NULL it isn't dead. 1391 1392 inline bool is_obj_dead(const oop obj) const; 1393 1394 inline bool is_obj_ill(const oop obj) const; 1395 1396 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1397 1398 // Refinement 1399 1400 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1401 1402 // Optimized nmethod scanning support routines 1403 1404 // Register the given nmethod with the G1 heap. 1405 virtual void register_nmethod(nmethod* nm); 1406 1407 // Unregister the given nmethod from the G1 heap. 1408 virtual void unregister_nmethod(nmethod* nm); 1409 1410 // Free up superfluous code root memory. 1411 void purge_code_root_memory(); 1412 1413 // Rebuild the strong code root lists for each region 1414 // after a full GC. 1415 void rebuild_strong_code_roots(); 1416 1417 // Partial cleaning used when class unloading is disabled. 1418 // Let the caller choose what structures to clean out: 1419 // - StringTable 1420 // - SymbolTable 1421 // - StringDeduplication structures 1422 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1423 1424 // Complete cleaning used when class unloading is enabled. 1425 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1426 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1427 1428 // Redirty logged cards in the refinement queue. 1429 void redirty_logged_cards(); 1430 // Verification 1431 1432 // Perform any cleanup actions necessary before allowing a verification. 1433 virtual void prepare_for_verify(); 1434 1435 // Perform verification. 1436 1437 // vo == UsePrevMarking -> use "prev" marking information, 1438 // vo == UseNextMarking -> use "next" marking information 1439 // vo == UseMarkWord -> use the mark word in the object header 1440 // 1441 // NOTE: Only the "prev" marking information is guaranteed to be 1442 // consistent most of the time, so most calls to this should use 1443 // vo == UsePrevMarking. 1444 // Currently, there is only one case where this is called with 1445 // vo == UseNextMarking, which is to verify the "next" marking 1446 // information at the end of remark. 1447 // Currently there is only one place where this is called with 1448 // vo == UseMarkWord, which is to verify the marking during a 1449 // full GC. 1450 void verify(VerifyOption vo); 1451 1452 // WhiteBox testing support. 1453 virtual bool supports_concurrent_phase_control() const; 1454 virtual const char* const* concurrent_phases() const; 1455 virtual bool request_concurrent_phase(const char* phase); 1456 1457 // The methods below are here for convenience and dispatch the 1458 // appropriate method depending on value of the given VerifyOption 1459 // parameter. The values for that parameter, and their meanings, 1460 // are the same as those above. 1461 1462 bool is_obj_dead_cond(const oop obj, 1463 const HeapRegion* hr, 1464 const VerifyOption vo) const; 1465 1466 bool is_obj_dead_cond(const oop obj, 1467 const VerifyOption vo) const; 1468 1469 G1HeapSummary create_g1_heap_summary(); 1470 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1471 1472 // Printing 1473 private: 1474 void print_heap_regions() const; 1475 void print_regions_on(outputStream* st) const; 1476 1477 public: 1478 virtual void print_on(outputStream* st) const; 1479 virtual void print_extended_on(outputStream* st) const; 1480 virtual void print_on_error(outputStream* st) const; 1481 1482 virtual void print_gc_threads_on(outputStream* st) const; 1483 virtual void gc_threads_do(ThreadClosure* tc) const; 1484 1485 // Override 1486 void print_tracing_info() const; 1487 1488 // The following two methods are helpful for debugging RSet issues. 1489 void print_cset_rsets() PRODUCT_RETURN; 1490 void print_all_rsets() PRODUCT_RETURN; 1491 1492 public: 1493 size_t pending_card_num(); 1494 1495 protected: 1496 size_t _max_heap_capacity; 1497 }; 1498 1499 class G1ParEvacuateFollowersClosure : public VoidClosure { 1500 private: 1501 double _start_term; 1502 double _term_time; 1503 size_t _term_attempts; 1504 1505 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1506 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1507 protected: 1508 G1CollectedHeap* _g1h; 1509 G1ParScanThreadState* _par_scan_state; 1510 RefToScanQueueSet* _queues; 1511 ParallelTaskTerminator* _terminator; 1512 1513 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1514 RefToScanQueueSet* queues() { return _queues; } 1515 ParallelTaskTerminator* terminator() { return _terminator; } 1516 1517 public: 1518 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1519 G1ParScanThreadState* par_scan_state, 1520 RefToScanQueueSet* queues, 1521 ParallelTaskTerminator* terminator) 1522 : _g1h(g1h), _par_scan_state(par_scan_state), 1523 _queues(queues), _terminator(terminator), 1524 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1525 1526 void do_void(); 1527 1528 double term_time() const { return _term_time; } 1529 size_t term_attempts() const { return _term_attempts; } 1530 1531 private: 1532 inline bool offer_termination(); 1533 }; 1534 1535 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP