rev 49184 : imported patch 8197569-refactor-eager-reclaim
1 /* 2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/evacuationInfo.hpp" 29 #include "gc/g1/g1BiasedArray.hpp" 30 #include "gc/g1/g1CardTable.hpp" 31 #include "gc/g1/g1CollectionSet.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1ConcurrentMark.hpp" 34 #include "gc/g1/g1EdenRegions.hpp" 35 #include "gc/g1/g1EvacFailure.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1HeapTransition.hpp" 38 #include "gc/g1/g1HeapVerifier.hpp" 39 #include "gc/g1/g1HRPrinter.hpp" 40 #include "gc/g1/g1InCSetState.hpp" 41 #include "gc/g1/g1MonitoringSupport.hpp" 42 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 43 #include "gc/g1/g1SurvivorRegions.hpp" 44 #include "gc/g1/g1YCTypes.hpp" 45 #include "gc/g1/heapRegionManager.hpp" 46 #include "gc/g1/heapRegionSet.hpp" 47 #include "gc/shared/barrierSet.hpp" 48 #include "gc/shared/collectedHeap.hpp" 49 #include "gc/shared/gcHeapSummary.hpp" 50 #include "gc/shared/plab.hpp" 51 #include "gc/shared/preservedMarks.hpp" 52 #include "gc/shared/softRefPolicy.hpp" 53 #include "memory/memRegion.hpp" 54 #include "services/memoryManager.hpp" 55 #include "utilities/stack.hpp" 56 57 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 58 // It uses the "Garbage First" heap organization and algorithm, which 59 // may combine concurrent marking with parallel, incremental compaction of 60 // heap subsets that will yield large amounts of garbage. 61 62 // Forward declarations 63 class HeapRegion; 64 class HRRSCleanupTask; 65 class GenerationSpec; 66 class G1ParScanThreadState; 67 class G1ParScanThreadStateSet; 68 class G1ParScanThreadState; 69 class MemoryPool; 70 class ObjectClosure; 71 class SpaceClosure; 72 class CompactibleSpaceClosure; 73 class Space; 74 class G1CollectionSet; 75 class G1CollectorPolicy; 76 class G1Policy; 77 class G1HotCardCache; 78 class G1RemSet; 79 class G1YoungRemSetSamplingThread; 80 class HeapRegionRemSetIterator; 81 class G1ConcurrentMark; 82 class ConcurrentMarkThread; 83 class G1ConcurrentRefine; 84 class GenerationCounters; 85 class STWGCTimer; 86 class G1NewTracer; 87 class EvacuationFailedInfo; 88 class nmethod; 89 class Ticks; 90 class WorkGang; 91 class G1Allocator; 92 class G1ArchiveAllocator; 93 class G1FullGCScope; 94 class G1HeapVerifier; 95 class G1HeapSizingPolicy; 96 class G1HeapSummary; 97 class G1EvacSummary; 98 99 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 100 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 101 102 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 103 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 104 105 // The G1 STW is alive closure. 106 // An instance is embedded into the G1CH and used as the 107 // (optional) _is_alive_non_header closure in the STW 108 // reference processor. It is also extensively used during 109 // reference processing during STW evacuation pauses. 110 class G1STWIsAliveClosure: public BoolObjectClosure { 111 G1CollectedHeap* _g1; 112 public: 113 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 114 bool do_object_b(oop p); 115 }; 116 117 class G1RegionMappingChangedListener : public G1MappingChangedListener { 118 private: 119 void reset_from_card_cache(uint start_idx, size_t num_regions); 120 public: 121 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 122 }; 123 124 class G1CollectedHeap : public CollectedHeap { 125 friend class G1FreeCollectionSetTask; 126 friend class VM_CollectForMetadataAllocation; 127 friend class VM_G1CollectForAllocation; 128 friend class VM_G1CollectFull; 129 friend class VMStructs; 130 friend class MutatorAllocRegion; 131 friend class G1FullCollector; 132 friend class G1GCAllocRegion; 133 friend class G1HeapVerifier; 134 135 // Closures used in implementation. 136 friend class G1ParScanThreadState; 137 friend class G1ParScanThreadStateSet; 138 friend class G1ParTask; 139 friend class G1PLABAllocator; 140 friend class G1PrepareCompactClosure; 141 142 // Other related classes. 143 friend class HeapRegionClaimer; 144 145 // Testing classes. 146 friend class G1CheckCSetFastTableClosure; 147 148 private: 149 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 150 151 WorkGang* _workers; 152 G1CollectorPolicy* _collector_policy; 153 G1CardTable* _card_table; 154 155 SoftRefPolicy _soft_ref_policy; 156 157 GCMemoryManager _memory_manager; 158 GCMemoryManager _full_gc_memory_manager; 159 160 MemoryPool* _eden_pool; 161 MemoryPool* _survivor_pool; 162 MemoryPool* _old_pool; 163 164 static size_t _humongous_object_threshold_in_words; 165 166 // The secondary free list which contains regions that have been 167 // freed up during the cleanup process. This will be appended to 168 // the master free list when appropriate. 169 FreeRegionList _secondary_free_list; 170 171 // It keeps track of the old regions. 172 HeapRegionSet _old_set; 173 174 // It keeps track of the humongous regions. 175 HeapRegionSet _humongous_set; 176 177 virtual void initialize_serviceability(); 178 179 void eagerly_reclaim_humongous_regions(); 180 // Start a new incremental collection set for the next pause. 181 void start_new_collection_set(); 182 183 // The number of regions we could create by expansion. 184 uint _expansion_regions; 185 186 // The block offset table for the G1 heap. 187 G1BlockOffsetTable* _bot; 188 189 // Tears down the region sets / lists so that they are empty and the 190 // regions on the heap do not belong to a region set / list. The 191 // only exception is the humongous set which we leave unaltered. If 192 // free_list_only is true, it will only tear down the master free 193 // list. It is called before a Full GC (free_list_only == false) or 194 // before heap shrinking (free_list_only == true). 195 void tear_down_region_sets(bool free_list_only); 196 197 // Rebuilds the region sets / lists so that they are repopulated to 198 // reflect the contents of the heap. The only exception is the 199 // humongous set which was not torn down in the first place. If 200 // free_list_only is true, it will only rebuild the master free 201 // list. It is called after a Full GC (free_list_only == false) or 202 // after heap shrinking (free_list_only == true). 203 void rebuild_region_sets(bool free_list_only); 204 205 // Callback for region mapping changed events. 206 G1RegionMappingChangedListener _listener; 207 208 // The sequence of all heap regions in the heap. 209 HeapRegionManager _hrm; 210 211 // Manages all allocations with regions except humongous object allocations. 212 G1Allocator* _allocator; 213 214 // Manages all heap verification. 215 G1HeapVerifier* _verifier; 216 217 // Outside of GC pauses, the number of bytes used in all regions other 218 // than the current allocation region(s). 219 size_t _summary_bytes_used; 220 221 void increase_used(size_t bytes); 222 void decrease_used(size_t bytes); 223 224 void set_used(size_t bytes); 225 226 // Class that handles archive allocation ranges. 227 G1ArchiveAllocator* _archive_allocator; 228 229 // GC allocation statistics policy for survivors. 230 G1EvacStats _survivor_evac_stats; 231 232 // GC allocation statistics policy for tenured objects. 233 G1EvacStats _old_evac_stats; 234 235 // It specifies whether we should attempt to expand the heap after a 236 // region allocation failure. If heap expansion fails we set this to 237 // false so that we don't re-attempt the heap expansion (it's likely 238 // that subsequent expansion attempts will also fail if one fails). 239 // Currently, it is only consulted during GC and it's reset at the 240 // start of each GC. 241 bool _expand_heap_after_alloc_failure; 242 243 // Helper for monitoring and management support. 244 G1MonitoringSupport* _g1mm; 245 246 // Records whether the region at the given index is (still) a 247 // candidate for eager reclaim. Only valid for humongous start 248 // regions; other regions have unspecified values. Humongous start 249 // regions are initialized at start of collection pause, with 250 // candidates removed from the set as they are found reachable from 251 // roots or the young generation. 252 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 253 protected: 254 bool default_value() const { return false; } 255 public: 256 void clear() { G1BiasedMappedArray<bool>::clear(); } 257 void set_candidate(uint region, bool value) { 258 set_by_index(region, value); 259 } 260 bool is_candidate(uint region) { 261 return get_by_index(region); 262 } 263 }; 264 265 HumongousReclaimCandidates _humongous_reclaim_candidates; 266 // Stores whether during humongous object registration we found candidate regions. 267 // If not, we can skip a few steps. 268 bool _has_humongous_reclaim_candidates; 269 270 volatile uint _gc_time_stamp; 271 272 G1HRPrinter _hr_printer; 273 274 // It decides whether an explicit GC should start a concurrent cycle 275 // instead of doing a STW GC. Currently, a concurrent cycle is 276 // explicitly started if: 277 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 278 // (b) cause == _g1_humongous_allocation 279 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 280 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 281 // (e) cause == _wb_conc_mark 282 bool should_do_concurrent_full_gc(GCCause::Cause cause); 283 284 // indicates whether we are in young or mixed GC mode 285 G1CollectorState _collector_state; 286 287 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 288 // concurrent cycles) we have started. 289 volatile uint _old_marking_cycles_started; 290 291 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 292 // concurrent cycles) we have completed. 293 volatile uint _old_marking_cycles_completed; 294 295 // This is a non-product method that is helpful for testing. It is 296 // called at the end of a GC and artificially expands the heap by 297 // allocating a number of dead regions. This way we can induce very 298 // frequent marking cycles and stress the cleanup / concurrent 299 // cleanup code more (as all the regions that will be allocated by 300 // this method will be found dead by the marking cycle). 301 void allocate_dummy_regions() PRODUCT_RETURN; 302 303 // Clear RSets after a compaction. It also resets the GC time stamps. 304 void clear_rsets_post_compaction(); 305 306 // If the HR printer is active, dump the state of the regions in the 307 // heap after a compaction. 308 void print_hrm_post_compaction(); 309 310 // Create a memory mapper for auxiliary data structures of the given size and 311 // translation factor. 312 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 313 size_t size, 314 size_t translation_factor); 315 316 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 317 318 // These are macros so that, if the assert fires, we get the correct 319 // line number, file, etc. 320 321 #define heap_locking_asserts_params(_extra_message_) \ 322 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 323 (_extra_message_), \ 324 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 325 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 326 BOOL_TO_STR(Thread::current()->is_VM_thread()) 327 328 #define assert_heap_locked() \ 329 do { \ 330 assert(Heap_lock->owned_by_self(), \ 331 heap_locking_asserts_params("should be holding the Heap_lock")); \ 332 } while (0) 333 334 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 335 do { \ 336 assert(Heap_lock->owned_by_self() || \ 337 (SafepointSynchronize::is_at_safepoint() && \ 338 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 339 heap_locking_asserts_params("should be holding the Heap_lock or " \ 340 "should be at a safepoint")); \ 341 } while (0) 342 343 #define assert_heap_locked_and_not_at_safepoint() \ 344 do { \ 345 assert(Heap_lock->owned_by_self() && \ 346 !SafepointSynchronize::is_at_safepoint(), \ 347 heap_locking_asserts_params("should be holding the Heap_lock and " \ 348 "should not be at a safepoint")); \ 349 } while (0) 350 351 #define assert_heap_not_locked() \ 352 do { \ 353 assert(!Heap_lock->owned_by_self(), \ 354 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 355 } while (0) 356 357 #define assert_heap_not_locked_and_not_at_safepoint() \ 358 do { \ 359 assert(!Heap_lock->owned_by_self() && \ 360 !SafepointSynchronize::is_at_safepoint(), \ 361 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 362 "should not be at a safepoint")); \ 363 } while (0) 364 365 #define assert_at_safepoint_on_vm_thread() \ 366 do { \ 367 assert_at_safepoint(); \ 368 assert(Thread::current_or_null() != NULL, "no current thread"); \ 369 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 370 } while (0) 371 372 protected: 373 374 // The young region list. 375 G1EdenRegions _eden; 376 G1SurvivorRegions _survivor; 377 378 STWGCTimer* _gc_timer_stw; 379 380 G1NewTracer* _gc_tracer_stw; 381 382 // The current policy object for the collector. 383 G1Policy* _g1_policy; 384 G1HeapSizingPolicy* _heap_sizing_policy; 385 386 G1CollectionSet _collection_set; 387 388 // This is the second level of trying to allocate a new region. If 389 // new_region() didn't find a region on the free_list, this call will 390 // check whether there's anything available on the 391 // secondary_free_list and/or wait for more regions to appear on 392 // that list, if _free_regions_coming is set. 393 HeapRegion* new_region_try_secondary_free_list(bool is_old); 394 395 // Try to allocate a single non-humongous HeapRegion sufficient for 396 // an allocation of the given word_size. If do_expand is true, 397 // attempt to expand the heap if necessary to satisfy the allocation 398 // request. If the region is to be used as an old region or for a 399 // humongous object, set is_old to true. If not, to false. 400 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 401 402 // Initialize a contiguous set of free regions of length num_regions 403 // and starting at index first so that they appear as a single 404 // humongous region. 405 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 406 uint num_regions, 407 size_t word_size); 408 409 // Attempt to allocate a humongous object of the given size. Return 410 // NULL if unsuccessful. 411 HeapWord* humongous_obj_allocate(size_t word_size); 412 413 // The following two methods, allocate_new_tlab() and 414 // mem_allocate(), are the two main entry points from the runtime 415 // into the G1's allocation routines. They have the following 416 // assumptions: 417 // 418 // * They should both be called outside safepoints. 419 // 420 // * They should both be called without holding the Heap_lock. 421 // 422 // * All allocation requests for new TLABs should go to 423 // allocate_new_tlab(). 424 // 425 // * All non-TLAB allocation requests should go to mem_allocate(). 426 // 427 // * If either call cannot satisfy the allocation request using the 428 // current allocating region, they will try to get a new one. If 429 // this fails, they will attempt to do an evacuation pause and 430 // retry the allocation. 431 // 432 // * If all allocation attempts fail, even after trying to schedule 433 // an evacuation pause, allocate_new_tlab() will return NULL, 434 // whereas mem_allocate() will attempt a heap expansion and/or 435 // schedule a Full GC. 436 // 437 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 438 // should never be called with word_size being humongous. All 439 // humongous allocation requests should go to mem_allocate() which 440 // will satisfy them with a special path. 441 442 virtual HeapWord* allocate_new_tlab(size_t word_size); 443 444 virtual HeapWord* mem_allocate(size_t word_size, 445 bool* gc_overhead_limit_was_exceeded); 446 447 // First-level mutator allocation attempt: try to allocate out of 448 // the mutator alloc region without taking the Heap_lock. This 449 // should only be used for non-humongous allocations. 450 inline HeapWord* attempt_allocation(size_t word_size); 451 452 // Second-level mutator allocation attempt: take the Heap_lock and 453 // retry the allocation attempt, potentially scheduling a GC 454 // pause. This should only be used for non-humongous allocations. 455 HeapWord* attempt_allocation_slow(size_t word_size); 456 457 // Takes the Heap_lock and attempts a humongous allocation. It can 458 // potentially schedule a GC pause. 459 HeapWord* attempt_allocation_humongous(size_t word_size); 460 461 // Allocation attempt that should be called during safepoints (e.g., 462 // at the end of a successful GC). expect_null_mutator_alloc_region 463 // specifies whether the mutator alloc region is expected to be NULL 464 // or not. 465 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 466 bool expect_null_mutator_alloc_region); 467 468 // These methods are the "callbacks" from the G1AllocRegion class. 469 470 // For mutator alloc regions. 471 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 472 void retire_mutator_alloc_region(HeapRegion* alloc_region, 473 size_t allocated_bytes); 474 475 // For GC alloc regions. 476 bool has_more_regions(InCSetState dest); 477 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 478 void retire_gc_alloc_region(HeapRegion* alloc_region, 479 size_t allocated_bytes, InCSetState dest); 480 481 // - if explicit_gc is true, the GC is for a System.gc() etc, 482 // otherwise it's for a failed allocation. 483 // - if clear_all_soft_refs is true, all soft references should be 484 // cleared during the GC. 485 // - it returns false if it is unable to do the collection due to the 486 // GC locker being active, true otherwise. 487 bool do_full_collection(bool explicit_gc, 488 bool clear_all_soft_refs); 489 490 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 491 virtual void do_full_collection(bool clear_all_soft_refs); 492 493 // Resize the heap if necessary after a full collection. 494 void resize_if_necessary_after_full_collection(); 495 496 // Callback from VM_G1CollectForAllocation operation. 497 // This function does everything necessary/possible to satisfy a 498 // failed allocation request (including collection, expansion, etc.) 499 HeapWord* satisfy_failed_allocation(size_t word_size, 500 bool* succeeded); 501 private: 502 // Internal helpers used during full GC to split it up to 503 // increase readability. 504 void abort_concurrent_cycle(); 505 void verify_before_full_collection(bool explicit_gc); 506 void prepare_heap_for_full_collection(); 507 void prepare_heap_for_mutators(); 508 void abort_refinement(); 509 void verify_after_full_collection(); 510 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 511 512 // Helper method for satisfy_failed_allocation() 513 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 514 bool do_gc, 515 bool clear_all_soft_refs, 516 bool expect_null_mutator_alloc_region, 517 bool* gc_succeeded); 518 519 protected: 520 // Attempting to expand the heap sufficiently 521 // to support an allocation of the given "word_size". If 522 // successful, perform the allocation and return the address of the 523 // allocated block, or else "NULL". 524 HeapWord* expand_and_allocate(size_t word_size); 525 526 // Preserve any referents discovered by concurrent marking that have not yet been 527 // copied by the STW pause. 528 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 529 // Process any reference objects discovered during 530 // an incremental evacuation pause. 531 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 532 533 // Enqueue any remaining discovered references 534 // after processing. 535 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 536 537 // Merges the information gathered on a per-thread basis for all worker threads 538 // during GC into global variables. 539 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 540 public: 541 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 542 543 WorkGang* workers() const { return _workers; } 544 545 G1Allocator* allocator() { 546 return _allocator; 547 } 548 549 G1HeapVerifier* verifier() { 550 return _verifier; 551 } 552 553 G1MonitoringSupport* g1mm() { 554 assert(_g1mm != NULL, "should have been initialized"); 555 return _g1mm; 556 } 557 558 // Expand the garbage-first heap by at least the given size (in bytes!). 559 // Returns true if the heap was expanded by the requested amount; 560 // false otherwise. 561 // (Rounds up to a HeapRegion boundary.) 562 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 563 564 // Returns the PLAB statistics for a given destination. 565 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 566 567 // Determines PLAB size for a given destination. 568 inline size_t desired_plab_sz(InCSetState dest); 569 570 // Do anything common to GC's. 571 void gc_prologue(bool full); 572 void gc_epilogue(bool full); 573 574 // Modify the reclaim candidate set and test for presence. 575 // These are only valid for starts_humongous regions. 576 inline void set_humongous_reclaim_candidate(uint region, bool value); 577 inline bool is_humongous_reclaim_candidate(uint region); 578 579 // Remove from the reclaim candidate set. Also remove from the 580 // collection set so that later encounters avoid the slow path. 581 inline void set_humongous_is_live(oop obj); 582 583 // Register the given region to be part of the collection set. 584 inline void register_humongous_region_with_cset(uint index); 585 // Register regions with humongous objects (actually on the start region) in 586 // the in_cset_fast_test table. 587 void register_humongous_regions_with_cset(); 588 // We register a region with the fast "in collection set" test. We 589 // simply set to true the array slot corresponding to this region. 590 void register_young_region_with_cset(HeapRegion* r) { 591 _in_cset_fast_test.set_in_young(r->hrm_index()); 592 } 593 void register_old_region_with_cset(HeapRegion* r) { 594 _in_cset_fast_test.set_in_old(r->hrm_index()); 595 } 596 void clear_in_cset(const HeapRegion* hr) { 597 _in_cset_fast_test.clear(hr); 598 } 599 600 void clear_cset_fast_test() { 601 _in_cset_fast_test.clear(); 602 } 603 604 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 605 606 // This is called at the start of either a concurrent cycle or a Full 607 // GC to update the number of old marking cycles started. 608 void increment_old_marking_cycles_started(); 609 610 // This is called at the end of either a concurrent cycle or a Full 611 // GC to update the number of old marking cycles completed. Those two 612 // can happen in a nested fashion, i.e., we start a concurrent 613 // cycle, a Full GC happens half-way through it which ends first, 614 // and then the cycle notices that a Full GC happened and ends 615 // too. The concurrent parameter is a boolean to help us do a bit 616 // tighter consistency checking in the method. If concurrent is 617 // false, the caller is the inner caller in the nesting (i.e., the 618 // Full GC). If concurrent is true, the caller is the outer caller 619 // in this nesting (i.e., the concurrent cycle). Further nesting is 620 // not currently supported. The end of this call also notifies 621 // the FullGCCount_lock in case a Java thread is waiting for a full 622 // GC to happen (e.g., it called System.gc() with 623 // +ExplicitGCInvokesConcurrent). 624 void increment_old_marking_cycles_completed(bool concurrent); 625 626 uint old_marking_cycles_completed() { 627 return _old_marking_cycles_completed; 628 } 629 630 G1HRPrinter* hr_printer() { return &_hr_printer; } 631 632 // Allocates a new heap region instance. 633 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 634 635 // Allocate the highest free region in the reserved heap. This will commit 636 // regions as necessary. 637 HeapRegion* alloc_highest_free_region(); 638 639 // Frees a non-humongous region by initializing its contents and 640 // adding it to the free list that's passed as a parameter (this is 641 // usually a local list which will be appended to the master free 642 // list later). The used bytes of freed regions are accumulated in 643 // pre_used. If skip_remset is true, the region's RSet will not be freed 644 // up. If skip_hot_card_cache is true, the region's hot card cache will not 645 // be freed up. The assumption is that this will be done later. 646 // The locked parameter indicates if the caller has already taken 647 // care of proper synchronization. This may allow some optimizations. 648 void free_region(HeapRegion* hr, 649 FreeRegionList* free_list, 650 bool skip_remset, 651 bool skip_hot_card_cache = false, 652 bool locked = false); 653 654 // It dirties the cards that cover the block so that the post 655 // write barrier never queues anything when updating objects on this 656 // block. It is assumed (and in fact we assert) that the block 657 // belongs to a young region. 658 inline void dirty_young_block(HeapWord* start, size_t word_size); 659 660 // Frees a humongous region by collapsing it into individual regions 661 // and calling free_region() for each of them. The freed regions 662 // will be added to the free list that's passed as a parameter (this 663 // is usually a local list which will be appended to the master free 664 // list later). The used bytes of freed regions are accumulated in 665 // pre_used. If skip_remset is true, the region's RSet will not be freed 666 // up. The assumption is that this will be done later. 667 void free_humongous_region(HeapRegion* hr, 668 FreeRegionList* free_list, 669 bool skip_remset); 670 671 // Facility for allocating in 'archive' regions in high heap memory and 672 // recording the allocated ranges. These should all be called from the 673 // VM thread at safepoints, without the heap lock held. They can be used 674 // to create and archive a set of heap regions which can be mapped at the 675 // same fixed addresses in a subsequent JVM invocation. 676 void begin_archive_alloc_range(bool open = false); 677 678 // Check if the requested size would be too large for an archive allocation. 679 bool is_archive_alloc_too_large(size_t word_size); 680 681 // Allocate memory of the requested size from the archive region. This will 682 // return NULL if the size is too large or if no memory is available. It 683 // does not trigger a garbage collection. 684 HeapWord* archive_mem_allocate(size_t word_size); 685 686 // Optionally aligns the end address and returns the allocated ranges in 687 // an array of MemRegions in order of ascending addresses. 688 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 689 size_t end_alignment_in_bytes = 0); 690 691 // Facility for allocating a fixed range within the heap and marking 692 // the containing regions as 'archive'. For use at JVM init time, when the 693 // caller may mmap archived heap data at the specified range(s). 694 // Verify that the MemRegions specified in the argument array are within the 695 // reserved heap. 696 bool check_archive_addresses(MemRegion* range, size_t count); 697 698 // Commit the appropriate G1 regions containing the specified MemRegions 699 // and mark them as 'archive' regions. The regions in the array must be 700 // non-overlapping and in order of ascending address. 701 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 702 703 // Insert any required filler objects in the G1 regions around the specified 704 // ranges to make the regions parseable. This must be called after 705 // alloc_archive_regions, and after class loading has occurred. 706 void fill_archive_regions(MemRegion* range, size_t count); 707 708 // For each of the specified MemRegions, uncommit the containing G1 regions 709 // which had been allocated by alloc_archive_regions. This should be called 710 // rather than fill_archive_regions at JVM init time if the archive file 711 // mapping failed, with the same non-overlapping and sorted MemRegion array. 712 void dealloc_archive_regions(MemRegion* range, size_t count); 713 714 protected: 715 716 // Shrink the garbage-first heap by at most the given size (in bytes!). 717 // (Rounds down to a HeapRegion boundary.) 718 virtual void shrink(size_t expand_bytes); 719 void shrink_helper(size_t expand_bytes); 720 721 #if TASKQUEUE_STATS 722 static void print_taskqueue_stats_hdr(outputStream* const st); 723 void print_taskqueue_stats() const; 724 void reset_taskqueue_stats(); 725 #endif // TASKQUEUE_STATS 726 727 // Schedule the VM operation that will do an evacuation pause to 728 // satisfy an allocation request of word_size. *succeeded will 729 // return whether the VM operation was successful (it did do an 730 // evacuation pause) or not (another thread beat us to it or the GC 731 // locker was active). Given that we should not be holding the 732 // Heap_lock when we enter this method, we will pass the 733 // gc_count_before (i.e., total_collections()) as a parameter since 734 // it has to be read while holding the Heap_lock. Currently, both 735 // methods that call do_collection_pause() release the Heap_lock 736 // before the call, so it's easy to read gc_count_before just before. 737 HeapWord* do_collection_pause(size_t word_size, 738 uint gc_count_before, 739 bool* succeeded, 740 GCCause::Cause gc_cause); 741 742 void wait_for_root_region_scanning(); 743 744 // The guts of the incremental collection pause, executed by the vm 745 // thread. It returns false if it is unable to do the collection due 746 // to the GC locker being active, true otherwise 747 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 748 749 // Actually do the work of evacuating the collection set. 750 virtual void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states); 751 752 void pre_evacuate_collection_set(); 753 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 754 755 // Print the header for the per-thread termination statistics. 756 static void print_termination_stats_hdr(); 757 // Print actual per-thread termination statistics. 758 void print_termination_stats(uint worker_id, 759 double elapsed_ms, 760 double strong_roots_ms, 761 double term_ms, 762 size_t term_attempts, 763 size_t alloc_buffer_waste, 764 size_t undo_waste) const; 765 // Update object copying statistics. 766 void record_obj_copy_mem_stats(); 767 768 // The hot card cache for remembered set insertion optimization. 769 G1HotCardCache* _hot_card_cache; 770 771 // The g1 remembered set of the heap. 772 G1RemSet* _g1_rem_set; 773 774 // A set of cards that cover the objects for which the Rsets should be updated 775 // concurrently after the collection. 776 DirtyCardQueueSet _dirty_card_queue_set; 777 778 // After a collection pause, convert the regions in the collection set into free 779 // regions. 780 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 781 782 // Abandon the current collection set without recording policy 783 // statistics or updating free lists. 784 void abandon_collection_set(G1CollectionSet* collection_set); 785 786 // The concurrent marker (and the thread it runs in.) 787 G1ConcurrentMark* _cm; 788 ConcurrentMarkThread* _cmThread; 789 790 // The concurrent refiner. 791 G1ConcurrentRefine* _cr; 792 793 // The parallel task queues 794 RefToScanQueueSet *_task_queues; 795 796 // True iff a evacuation has failed in the current collection. 797 bool _evacuation_failed; 798 799 EvacuationFailedInfo* _evacuation_failed_info_array; 800 801 // Failed evacuations cause some logical from-space objects to have 802 // forwarding pointers to themselves. Reset them. 803 void remove_self_forwarding_pointers(); 804 805 // Restore the objects in the regions in the collection set after an 806 // evacuation failure. 807 void restore_after_evac_failure(); 808 809 PreservedMarksSet _preserved_marks_set; 810 811 // Preserve the mark of "obj", if necessary, in preparation for its mark 812 // word being overwritten with a self-forwarding-pointer. 813 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 814 815 #ifndef PRODUCT 816 // Support for forcing evacuation failures. Analogous to 817 // PromotionFailureALot for the other collectors. 818 819 // Records whether G1EvacuationFailureALot should be in effect 820 // for the current GC 821 bool _evacuation_failure_alot_for_current_gc; 822 823 // Used to record the GC number for interval checking when 824 // determining whether G1EvaucationFailureALot is in effect 825 // for the current GC. 826 size_t _evacuation_failure_alot_gc_number; 827 828 // Count of the number of evacuations between failures. 829 volatile size_t _evacuation_failure_alot_count; 830 831 // Set whether G1EvacuationFailureALot should be in effect 832 // for the current GC (based upon the type of GC and which 833 // command line flags are set); 834 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 835 bool during_initial_mark, 836 bool during_marking); 837 838 inline void set_evacuation_failure_alot_for_current_gc(); 839 840 // Return true if it's time to cause an evacuation failure. 841 inline bool evacuation_should_fail(); 842 843 // Reset the G1EvacuationFailureALot counters. Should be called at 844 // the end of an evacuation pause in which an evacuation failure occurred. 845 inline void reset_evacuation_should_fail(); 846 #endif // !PRODUCT 847 848 // ("Weak") Reference processing support. 849 // 850 // G1 has 2 instances of the reference processor class. One 851 // (_ref_processor_cm) handles reference object discovery 852 // and subsequent processing during concurrent marking cycles. 853 // 854 // The other (_ref_processor_stw) handles reference object 855 // discovery and processing during full GCs and incremental 856 // evacuation pauses. 857 // 858 // During an incremental pause, reference discovery will be 859 // temporarily disabled for _ref_processor_cm and will be 860 // enabled for _ref_processor_stw. At the end of the evacuation 861 // pause references discovered by _ref_processor_stw will be 862 // processed and discovery will be disabled. The previous 863 // setting for reference object discovery for _ref_processor_cm 864 // will be re-instated. 865 // 866 // At the start of marking: 867 // * Discovery by the CM ref processor is verified to be inactive 868 // and it's discovered lists are empty. 869 // * Discovery by the CM ref processor is then enabled. 870 // 871 // At the end of marking: 872 // * Any references on the CM ref processor's discovered 873 // lists are processed (possibly MT). 874 // 875 // At the start of full GC we: 876 // * Disable discovery by the CM ref processor and 877 // empty CM ref processor's discovered lists 878 // (without processing any entries). 879 // * Verify that the STW ref processor is inactive and it's 880 // discovered lists are empty. 881 // * Temporarily set STW ref processor discovery as single threaded. 882 // * Temporarily clear the STW ref processor's _is_alive_non_header 883 // field. 884 // * Finally enable discovery by the STW ref processor. 885 // 886 // The STW ref processor is used to record any discovered 887 // references during the full GC. 888 // 889 // At the end of a full GC we: 890 // * Enqueue any reference objects discovered by the STW ref processor 891 // that have non-live referents. This has the side-effect of 892 // making the STW ref processor inactive by disabling discovery. 893 // * Verify that the CM ref processor is still inactive 894 // and no references have been placed on it's discovered 895 // lists (also checked as a precondition during initial marking). 896 897 // The (stw) reference processor... 898 ReferenceProcessor* _ref_processor_stw; 899 900 // During reference object discovery, the _is_alive_non_header 901 // closure (if non-null) is applied to the referent object to 902 // determine whether the referent is live. If so then the 903 // reference object does not need to be 'discovered' and can 904 // be treated as a regular oop. This has the benefit of reducing 905 // the number of 'discovered' reference objects that need to 906 // be processed. 907 // 908 // Instance of the is_alive closure for embedding into the 909 // STW reference processor as the _is_alive_non_header field. 910 // Supplying a value for the _is_alive_non_header field is 911 // optional but doing so prevents unnecessary additions to 912 // the discovered lists during reference discovery. 913 G1STWIsAliveClosure _is_alive_closure_stw; 914 915 // The (concurrent marking) reference processor... 916 ReferenceProcessor* _ref_processor_cm; 917 918 // Instance of the concurrent mark is_alive closure for embedding 919 // into the Concurrent Marking reference processor as the 920 // _is_alive_non_header field. Supplying a value for the 921 // _is_alive_non_header field is optional but doing so prevents 922 // unnecessary additions to the discovered lists during reference 923 // discovery. 924 G1CMIsAliveClosure _is_alive_closure_cm; 925 926 volatile bool _free_regions_coming; 927 928 public: 929 930 RefToScanQueue *task_queue(uint i) const; 931 932 uint num_task_queues() const; 933 934 // A set of cards where updates happened during the GC 935 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 936 937 // Create a G1CollectedHeap with the specified policy. 938 // Must call the initialize method afterwards. 939 // May not return if something goes wrong. 940 G1CollectedHeap(G1CollectorPolicy* policy); 941 942 private: 943 jint initialize_concurrent_refinement(); 944 jint initialize_young_gen_sampling_thread(); 945 public: 946 // Initialize the G1CollectedHeap to have the initial and 947 // maximum sizes and remembered and barrier sets 948 // specified by the policy object. 949 jint initialize(); 950 951 virtual void stop(); 952 virtual void safepoint_synchronize_begin(); 953 virtual void safepoint_synchronize_end(); 954 955 // Return the (conservative) maximum heap alignment for any G1 heap 956 static size_t conservative_max_heap_alignment(); 957 958 // Does operations required after initialization has been done. 959 void post_initialize(); 960 961 // Initialize weak reference processing. 962 void ref_processing_init(); 963 964 virtual Name kind() const { 965 return CollectedHeap::G1CollectedHeap; 966 } 967 968 virtual const char* name() const { 969 return "G1"; 970 } 971 972 const G1CollectorState* collector_state() const { return &_collector_state; } 973 G1CollectorState* collector_state() { return &_collector_state; } 974 975 // The current policy object for the collector. 976 G1Policy* g1_policy() const { return _g1_policy; } 977 978 const G1CollectionSet* collection_set() const { return &_collection_set; } 979 G1CollectionSet* collection_set() { return &_collection_set; } 980 981 virtual CollectorPolicy* collector_policy() const; 982 983 virtual SoftRefPolicy* soft_ref_policy(); 984 985 virtual GrowableArray<GCMemoryManager*> memory_managers(); 986 virtual GrowableArray<MemoryPool*> memory_pools(); 987 988 // The rem set and barrier set. 989 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 990 991 // Try to minimize the remembered set. 992 void scrub_rem_set(); 993 994 uint get_gc_time_stamp() { 995 return _gc_time_stamp; 996 } 997 998 inline void reset_gc_time_stamp(); 999 1000 void check_gc_time_stamps() PRODUCT_RETURN; 1001 1002 inline void increment_gc_time_stamp(); 1003 1004 // Reset the given region's GC timestamp. If it's starts humongous, 1005 // also reset the GC timestamp of its corresponding 1006 // continues humongous regions too. 1007 void reset_gc_time_stamps(HeapRegion* hr); 1008 1009 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1010 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1011 1012 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1013 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1014 1015 // The shared block offset table array. 1016 G1BlockOffsetTable* bot() const { return _bot; } 1017 1018 // Reference Processing accessors 1019 1020 // The STW reference processor.... 1021 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1022 1023 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1024 1025 // The Concurrent Marking reference processor... 1026 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1027 1028 size_t unused_committed_regions_in_bytes() const; 1029 virtual size_t capacity() const; 1030 virtual size_t used() const; 1031 // This should be called when we're not holding the heap lock. The 1032 // result might be a bit inaccurate. 1033 size_t used_unlocked() const; 1034 size_t recalculate_used() const; 1035 1036 // These virtual functions do the actual allocation. 1037 // Some heaps may offer a contiguous region for shared non-blocking 1038 // allocation, via inlined code (by exporting the address of the top and 1039 // end fields defining the extent of the contiguous allocation region.) 1040 // But G1CollectedHeap doesn't yet support this. 1041 1042 virtual bool is_maximal_no_gc() const { 1043 return _hrm.available() == 0; 1044 } 1045 1046 // Returns whether there are any regions left in the heap for allocation. 1047 bool has_regions_left_for_allocation() const { 1048 return !is_maximal_no_gc() || num_free_regions() != 0; 1049 } 1050 1051 // The current number of regions in the heap. 1052 uint num_regions() const { return _hrm.length(); } 1053 1054 // The max number of regions in the heap. 1055 uint max_regions() const { return _hrm.max_length(); } 1056 1057 // The number of regions that are completely free. 1058 uint num_free_regions() const { return _hrm.num_free_regions(); } 1059 1060 MemoryUsage get_auxiliary_data_memory_usage() const { 1061 return _hrm.get_auxiliary_data_memory_usage(); 1062 } 1063 1064 // The number of regions that are not completely free. 1065 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1066 1067 #ifdef ASSERT 1068 bool is_on_master_free_list(HeapRegion* hr) { 1069 return _hrm.is_free(hr); 1070 } 1071 #endif // ASSERT 1072 1073 // Wrapper for the region list operations that can be called from 1074 // methods outside this class. 1075 1076 void secondary_free_list_add(FreeRegionList* list) { 1077 _secondary_free_list.add_ordered(list); 1078 } 1079 1080 void append_secondary_free_list() { 1081 _hrm.insert_list_into_free_list(&_secondary_free_list); 1082 } 1083 1084 void append_secondary_free_list_if_not_empty_with_lock() { 1085 // If the secondary free list looks empty there's no reason to 1086 // take the lock and then try to append it. 1087 if (!_secondary_free_list.is_empty()) { 1088 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1089 append_secondary_free_list(); 1090 } 1091 } 1092 1093 inline void old_set_add(HeapRegion* hr); 1094 inline void old_set_remove(HeapRegion* hr); 1095 1096 size_t non_young_capacity_bytes() { 1097 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1098 } 1099 1100 void set_free_regions_coming(); 1101 void reset_free_regions_coming(); 1102 bool free_regions_coming() { return _free_regions_coming; } 1103 void wait_while_free_regions_coming(); 1104 1105 // Determine whether the given region is one that we are using as an 1106 // old GC alloc region. 1107 bool is_old_gc_alloc_region(HeapRegion* hr); 1108 1109 // Perform a collection of the heap; intended for use in implementing 1110 // "System.gc". This probably implies as full a collection as the 1111 // "CollectedHeap" supports. 1112 virtual void collect(GCCause::Cause cause); 1113 1114 // True iff an evacuation has failed in the most-recent collection. 1115 bool evacuation_failed() { return _evacuation_failed; } 1116 1117 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1118 void prepend_to_freelist(FreeRegionList* list); 1119 void decrement_summary_bytes(size_t bytes); 1120 1121 virtual bool is_in(const void* p) const; 1122 #ifdef ASSERT 1123 // Returns whether p is in one of the available areas of the heap. Slow but 1124 // extensive version. 1125 bool is_in_exact(const void* p) const; 1126 #endif 1127 1128 // Return "TRUE" iff the given object address is within the collection 1129 // set. Assumes that the reference points into the heap. 1130 inline bool is_in_cset(const HeapRegion *hr); 1131 inline bool is_in_cset(oop obj); 1132 inline bool is_in_cset(HeapWord* addr); 1133 1134 inline bool is_in_cset_or_humongous(const oop obj); 1135 1136 private: 1137 // This array is used for a quick test on whether a reference points into 1138 // the collection set or not. Each of the array's elements denotes whether the 1139 // corresponding region is in the collection set or not. 1140 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1141 1142 public: 1143 1144 inline InCSetState in_cset_state(const oop obj); 1145 1146 // Return "TRUE" iff the given object address is in the reserved 1147 // region of g1. 1148 bool is_in_g1_reserved(const void* p) const { 1149 return _hrm.reserved().contains(p); 1150 } 1151 1152 // Returns a MemRegion that corresponds to the space that has been 1153 // reserved for the heap 1154 MemRegion g1_reserved() const { 1155 return _hrm.reserved(); 1156 } 1157 1158 virtual bool is_in_closed_subset(const void* p) const; 1159 1160 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1161 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1162 } 1163 1164 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1165 1166 G1CardTable* card_table() const { 1167 return _card_table; 1168 } 1169 1170 // Iteration functions. 1171 1172 // Iterate over all objects, calling "cl.do_object" on each. 1173 virtual void object_iterate(ObjectClosure* cl); 1174 1175 virtual void safe_object_iterate(ObjectClosure* cl) { 1176 object_iterate(cl); 1177 } 1178 1179 // Iterate over heap regions, in address order, terminating the 1180 // iteration early if the "do_heap_region" method returns "true". 1181 void heap_region_iterate(HeapRegionClosure* blk) const; 1182 1183 // Return the region with the given index. It assumes the index is valid. 1184 inline HeapRegion* region_at(uint index) const; 1185 1186 // Return the next region (by index) that is part of the same 1187 // humongous object that hr is part of. 1188 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1189 1190 // Calculate the region index of the given address. Given address must be 1191 // within the heap. 1192 inline uint addr_to_region(HeapWord* addr) const; 1193 1194 inline HeapWord* bottom_addr_for_region(uint index) const; 1195 1196 // Two functions to iterate over the heap regions in parallel. Threads 1197 // compete using the HeapRegionClaimer to claim the regions before 1198 // applying the closure on them. 1199 // The _from_worker_offset version uses the HeapRegionClaimer and 1200 // the worker id to calculate a start offset to prevent all workers to 1201 // start from the point. 1202 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1203 HeapRegionClaimer* hrclaimer, 1204 uint worker_id) const; 1205 1206 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1207 HeapRegionClaimer* hrclaimer) const; 1208 1209 // Iterate over the regions (if any) in the current collection set. 1210 void collection_set_iterate(HeapRegionClosure* blk); 1211 1212 // Iterate over the regions (if any) in the current collection set. Starts the 1213 // iteration over the entire collection set so that the start regions of a given 1214 // worker id over the set active_workers are evenly spread across the set of 1215 // collection set regions. 1216 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1217 1218 // Returns the HeapRegion that contains addr. addr must not be NULL. 1219 template <class T> 1220 inline HeapRegion* heap_region_containing(const T addr) const; 1221 1222 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1223 // each address in the (reserved) heap is a member of exactly 1224 // one block. The defining characteristic of a block is that it is 1225 // possible to find its size, and thus to progress forward to the next 1226 // block. (Blocks may be of different sizes.) Thus, blocks may 1227 // represent Java objects, or they might be free blocks in a 1228 // free-list-based heap (or subheap), as long as the two kinds are 1229 // distinguishable and the size of each is determinable. 1230 1231 // Returns the address of the start of the "block" that contains the 1232 // address "addr". We say "blocks" instead of "object" since some heaps 1233 // may not pack objects densely; a chunk may either be an object or a 1234 // non-object. 1235 virtual HeapWord* block_start(const void* addr) const; 1236 1237 // Requires "addr" to be the start of a chunk, and returns its size. 1238 // "addr + size" is required to be the start of a new chunk, or the end 1239 // of the active area of the heap. 1240 virtual size_t block_size(const HeapWord* addr) const; 1241 1242 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1243 // the block is an object. 1244 virtual bool block_is_obj(const HeapWord* addr) const; 1245 1246 // Section on thread-local allocation buffers (TLABs) 1247 // See CollectedHeap for semantics. 1248 1249 bool supports_tlab_allocation() const; 1250 size_t tlab_capacity(Thread* ignored) const; 1251 size_t tlab_used(Thread* ignored) const; 1252 size_t max_tlab_size() const; 1253 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1254 1255 inline bool is_in_young(const oop obj); 1256 1257 // Returns "true" iff the given word_size is "very large". 1258 static bool is_humongous(size_t word_size) { 1259 // Note this has to be strictly greater-than as the TLABs 1260 // are capped at the humongous threshold and we want to 1261 // ensure that we don't try to allocate a TLAB as 1262 // humongous and that we don't allocate a humongous 1263 // object in a TLAB. 1264 return word_size > _humongous_object_threshold_in_words; 1265 } 1266 1267 // Returns the humongous threshold for a specific region size 1268 static size_t humongous_threshold_for(size_t region_size) { 1269 return (region_size / 2); 1270 } 1271 1272 // Returns the number of regions the humongous object of the given word size 1273 // requires. 1274 static size_t humongous_obj_size_in_regions(size_t word_size); 1275 1276 // Print the maximum heap capacity. 1277 virtual size_t max_capacity() const; 1278 1279 virtual jlong millis_since_last_gc(); 1280 1281 1282 // Convenience function to be used in situations where the heap type can be 1283 // asserted to be this type. 1284 static G1CollectedHeap* heap(); 1285 1286 void set_region_short_lived_locked(HeapRegion* hr); 1287 // add appropriate methods for any other surv rate groups 1288 1289 const G1SurvivorRegions* survivor() const { return &_survivor; } 1290 1291 uint survivor_regions_count() const { 1292 return _survivor.length(); 1293 } 1294 1295 uint eden_regions_count() const { 1296 return _eden.length(); 1297 } 1298 1299 uint young_regions_count() const { 1300 return _eden.length() + _survivor.length(); 1301 } 1302 1303 uint old_regions_count() const { return _old_set.length(); } 1304 1305 uint humongous_regions_count() const { return _humongous_set.length(); } 1306 1307 #ifdef ASSERT 1308 bool check_young_list_empty(); 1309 #endif 1310 1311 // *** Stuff related to concurrent marking. It's not clear to me that so 1312 // many of these need to be public. 1313 1314 // The functions below are helper functions that a subclass of 1315 // "CollectedHeap" can use in the implementation of its virtual 1316 // functions. 1317 // This performs a concurrent marking of the live objects in a 1318 // bitmap off to the side. 1319 void doConcurrentMark(); 1320 1321 bool isMarkedNext(oop obj) const; 1322 1323 // Determine if an object is dead, given the object and also 1324 // the region to which the object belongs. An object is dead 1325 // iff a) it was not allocated since the last mark, b) it 1326 // is not marked, and c) it is not in an archive region. 1327 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1328 return 1329 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1330 !hr->is_archive(); 1331 } 1332 1333 // This function returns true when an object has been 1334 // around since the previous marking and hasn't yet 1335 // been marked during this marking, and is not in an archive region. 1336 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1337 return 1338 !hr->obj_allocated_since_next_marking(obj) && 1339 !isMarkedNext(obj) && 1340 !hr->is_archive(); 1341 } 1342 1343 // Determine if an object is dead, given only the object itself. 1344 // This will find the region to which the object belongs and 1345 // then call the region version of the same function. 1346 1347 // Added if it is NULL it isn't dead. 1348 1349 inline bool is_obj_dead(const oop obj) const; 1350 1351 inline bool is_obj_ill(const oop obj) const; 1352 1353 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1354 inline bool is_obj_dead_full(const oop obj) const; 1355 1356 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1357 1358 // Refinement 1359 1360 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1361 1362 // Optimized nmethod scanning support routines 1363 1364 // Is an oop scavengeable 1365 virtual bool is_scavengable(oop obj); 1366 1367 // Register the given nmethod with the G1 heap. 1368 virtual void register_nmethod(nmethod* nm); 1369 1370 // Unregister the given nmethod from the G1 heap. 1371 virtual void unregister_nmethod(nmethod* nm); 1372 1373 // Free up superfluous code root memory. 1374 void purge_code_root_memory(); 1375 1376 // Rebuild the strong code root lists for each region 1377 // after a full GC. 1378 void rebuild_strong_code_roots(); 1379 1380 // Partial cleaning used when class unloading is disabled. 1381 // Let the caller choose what structures to clean out: 1382 // - StringTable 1383 // - SymbolTable 1384 // - StringDeduplication structures 1385 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1386 1387 // Complete cleaning used when class unloading is enabled. 1388 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1389 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1390 1391 // Redirty logged cards in the refinement queue. 1392 void redirty_logged_cards(); 1393 // Verification 1394 1395 // Perform any cleanup actions necessary before allowing a verification. 1396 virtual void prepare_for_verify(); 1397 1398 // Perform verification. 1399 1400 // vo == UsePrevMarking -> use "prev" marking information, 1401 // vo == UseNextMarking -> use "next" marking information 1402 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1403 // 1404 // NOTE: Only the "prev" marking information is guaranteed to be 1405 // consistent most of the time, so most calls to this should use 1406 // vo == UsePrevMarking. 1407 // Currently, there is only one case where this is called with 1408 // vo == UseNextMarking, which is to verify the "next" marking 1409 // information at the end of remark. 1410 // Currently there is only one place where this is called with 1411 // vo == UseFullMarking, which is to verify the marking during a 1412 // full GC. 1413 void verify(VerifyOption vo); 1414 1415 // WhiteBox testing support. 1416 virtual bool supports_concurrent_phase_control() const; 1417 virtual const char* const* concurrent_phases() const; 1418 virtual bool request_concurrent_phase(const char* phase); 1419 1420 // The methods below are here for convenience and dispatch the 1421 // appropriate method depending on value of the given VerifyOption 1422 // parameter. The values for that parameter, and their meanings, 1423 // are the same as those above. 1424 1425 bool is_obj_dead_cond(const oop obj, 1426 const HeapRegion* hr, 1427 const VerifyOption vo) const; 1428 1429 bool is_obj_dead_cond(const oop obj, 1430 const VerifyOption vo) const; 1431 1432 G1HeapSummary create_g1_heap_summary(); 1433 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1434 1435 // Printing 1436 private: 1437 void print_heap_regions() const; 1438 void print_regions_on(outputStream* st) const; 1439 1440 public: 1441 virtual void print_on(outputStream* st) const; 1442 virtual void print_extended_on(outputStream* st) const; 1443 virtual void print_on_error(outputStream* st) const; 1444 1445 virtual void print_gc_threads_on(outputStream* st) const; 1446 virtual void gc_threads_do(ThreadClosure* tc) const; 1447 1448 // Override 1449 void print_tracing_info() const; 1450 1451 // The following two methods are helpful for debugging RSet issues. 1452 void print_cset_rsets() PRODUCT_RETURN; 1453 void print_all_rsets() PRODUCT_RETURN; 1454 1455 public: 1456 size_t pending_card_num(); 1457 1458 protected: 1459 size_t _max_heap_capacity; 1460 }; 1461 1462 class G1ParEvacuateFollowersClosure : public VoidClosure { 1463 private: 1464 double _start_term; 1465 double _term_time; 1466 size_t _term_attempts; 1467 1468 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1469 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1470 protected: 1471 G1CollectedHeap* _g1h; 1472 G1ParScanThreadState* _par_scan_state; 1473 RefToScanQueueSet* _queues; 1474 ParallelTaskTerminator* _terminator; 1475 1476 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1477 RefToScanQueueSet* queues() { return _queues; } 1478 ParallelTaskTerminator* terminator() { return _terminator; } 1479 1480 public: 1481 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1482 G1ParScanThreadState* par_scan_state, 1483 RefToScanQueueSet* queues, 1484 ParallelTaskTerminator* terminator) 1485 : _g1h(g1h), _par_scan_state(par_scan_state), 1486 _queues(queues), _terminator(terminator), 1487 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1488 1489 void do_void(); 1490 1491 double term_time() const { return _term_time; } 1492 size_t term_attempts() const { return _term_attempts; } 1493 1494 private: 1495 inline bool offer_termination(); 1496 }; 1497 1498 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP --- EOF ---