1 /* 2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/evacuationInfo.hpp" 29 #include "gc/g1/g1AllocationContext.hpp" 30 #include "gc/g1/g1BiasedArray.hpp" 31 #include "gc/g1/g1CollectionSet.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1ConcurrentMark.hpp" 34 #include "gc/g1/g1EdenRegions.hpp" 35 #include "gc/g1/g1EvacFailure.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1HeapTransition.hpp" 38 #include "gc/g1/g1HeapVerifier.hpp" 39 #include "gc/g1/g1HRPrinter.hpp" 40 #include "gc/g1/g1InCSetState.hpp" 41 #include "gc/g1/g1MonitoringSupport.hpp" 42 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 43 #include "gc/g1/g1SurvivorRegions.hpp" 44 #include "gc/g1/g1YCTypes.hpp" 45 #include "gc/g1/hSpaceCounters.hpp" 46 #include "gc/g1/heapRegionManager.hpp" 47 #include "gc/g1/heapRegionSet.hpp" 48 #include "gc/shared/barrierSet.hpp" 49 #include "gc/shared/collectedHeap.hpp" 50 #include "gc/shared/plab.hpp" 51 #include "gc/shared/preservedMarks.hpp" 52 #include "memory/memRegion.hpp" 53 #include "utilities/stack.hpp" 54 55 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 56 // It uses the "Garbage First" heap organization and algorithm, which 57 // may combine concurrent marking with parallel, incremental compaction of 58 // heap subsets that will yield large amounts of garbage. 59 60 // Forward declarations 61 class HeapRegion; 62 class HRRSCleanupTask; 63 class GenerationSpec; 64 class G1ParScanThreadState; 65 class G1ParScanThreadStateSet; 66 class G1KlassScanClosure; 67 class G1ParScanThreadState; 68 class ObjectClosure; 69 class SpaceClosure; 70 class CompactibleSpaceClosure; 71 class Space; 72 class G1CollectionSet; 73 class G1CollectorPolicy; 74 class G1Policy; 75 class G1HotCardCache; 76 class G1RemSet; 77 class HeapRegionRemSetIterator; 78 class G1ConcurrentMark; 79 class ConcurrentMarkThread; 80 class ConcurrentG1Refine; 81 class GenerationCounters; 82 class STWGCTimer; 83 class G1NewTracer; 84 class EvacuationFailedInfo; 85 class nmethod; 86 class Ticks; 87 class WorkGang; 88 class G1Allocator; 89 class G1ArchiveAllocator; 90 class G1FullGCScope; 91 class G1HeapVerifier; 92 class G1HeapSizingPolicy; 93 class G1HeapSummary; 94 class G1EvacSummary; 95 96 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 97 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 98 99 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 100 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 101 102 // The G1 STW is alive closure. 103 // An instance is embedded into the G1CH and used as the 104 // (optional) _is_alive_non_header closure in the STW 105 // reference processor. It is also extensively used during 106 // reference processing during STW evacuation pauses. 107 class G1STWIsAliveClosure: public BoolObjectClosure { 108 G1CollectedHeap* _g1; 109 public: 110 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 111 bool do_object_b(oop p); 112 }; 113 114 class G1RegionMappingChangedListener : public G1MappingChangedListener { 115 private: 116 void reset_from_card_cache(uint start_idx, size_t num_regions); 117 public: 118 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 119 }; 120 121 class G1CollectedHeap : public CollectedHeap { 122 friend class G1FreeCollectionSetTask; 123 friend class VM_CollectForMetadataAllocation; 124 friend class VM_G1CollectForAllocation; 125 friend class VM_G1CollectFull; 126 friend class VM_G1IncCollectionPause; 127 friend class VMStructs; 128 friend class MutatorAllocRegion; 129 friend class G1GCAllocRegion; 130 friend class G1HeapVerifier; 131 132 // Closures used in implementation. 133 friend class G1ParScanThreadState; 134 friend class G1ParScanThreadStateSet; 135 friend class G1ParTask; 136 friend class G1PLABAllocator; 137 friend class G1PrepareCompactClosure; 138 139 // Other related classes. 140 friend class HeapRegionClaimer; 141 142 // Testing classes. 143 friend class G1CheckCSetFastTableClosure; 144 145 private: 146 WorkGang* _workers; 147 G1CollectorPolicy* _collector_policy; 148 149 static size_t _humongous_object_threshold_in_words; 150 151 // The secondary free list which contains regions that have been 152 // freed up during the cleanup process. This will be appended to 153 // the master free list when appropriate. 154 FreeRegionList _secondary_free_list; 155 156 // It keeps track of the old regions. 157 HeapRegionSet _old_set; 158 159 // It keeps track of the humongous regions. 160 HeapRegionSet _humongous_set; 161 162 void eagerly_reclaim_humongous_regions(); 163 // Start a new incremental collection set for the next pause. 164 void start_new_collection_set(); 165 166 // The number of regions we could create by expansion. 167 uint _expansion_regions; 168 169 // The block offset table for the G1 heap. 170 G1BlockOffsetTable* _bot; 171 172 // Tears down the region sets / lists so that they are empty and the 173 // regions on the heap do not belong to a region set / list. The 174 // only exception is the humongous set which we leave unaltered. If 175 // free_list_only is true, it will only tear down the master free 176 // list. It is called before a Full GC (free_list_only == false) or 177 // before heap shrinking (free_list_only == true). 178 void tear_down_region_sets(bool free_list_only); 179 180 // Rebuilds the region sets / lists so that they are repopulated to 181 // reflect the contents of the heap. The only exception is the 182 // humongous set which was not torn down in the first place. If 183 // free_list_only is true, it will only rebuild the master free 184 // list. It is called after a Full GC (free_list_only == false) or 185 // after heap shrinking (free_list_only == true). 186 void rebuild_region_sets(bool free_list_only); 187 188 // Callback for region mapping changed events. 189 G1RegionMappingChangedListener _listener; 190 191 // The sequence of all heap regions in the heap. 192 HeapRegionManager _hrm; 193 194 // Manages all allocations with regions except humongous object allocations. 195 G1Allocator* _allocator; 196 197 // Manages all heap verification. 198 G1HeapVerifier* _verifier; 199 200 // Outside of GC pauses, the number of bytes used in all regions other 201 // than the current allocation region(s). 202 size_t _summary_bytes_used; 203 204 void increase_used(size_t bytes); 205 void decrease_used(size_t bytes); 206 207 void set_used(size_t bytes); 208 209 // Class that handles archive allocation ranges. 210 G1ArchiveAllocator* _archive_allocator; 211 212 // Statistics for each allocation context 213 AllocationContextStats _allocation_context_stats; 214 215 // GC allocation statistics policy for survivors. 216 G1EvacStats _survivor_evac_stats; 217 218 // GC allocation statistics policy for tenured objects. 219 G1EvacStats _old_evac_stats; 220 221 // It specifies whether we should attempt to expand the heap after a 222 // region allocation failure. If heap expansion fails we set this to 223 // false so that we don't re-attempt the heap expansion (it's likely 224 // that subsequent expansion attempts will also fail if one fails). 225 // Currently, it is only consulted during GC and it's reset at the 226 // start of each GC. 227 bool _expand_heap_after_alloc_failure; 228 229 // Helper for monitoring and management support. 230 G1MonitoringSupport* _g1mm; 231 232 // Records whether the region at the given index is (still) a 233 // candidate for eager reclaim. Only valid for humongous start 234 // regions; other regions have unspecified values. Humongous start 235 // regions are initialized at start of collection pause, with 236 // candidates removed from the set as they are found reachable from 237 // roots or the young generation. 238 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 239 protected: 240 bool default_value() const { return false; } 241 public: 242 void clear() { G1BiasedMappedArray<bool>::clear(); } 243 void set_candidate(uint region, bool value) { 244 set_by_index(region, value); 245 } 246 bool is_candidate(uint region) { 247 return get_by_index(region); 248 } 249 }; 250 251 HumongousReclaimCandidates _humongous_reclaim_candidates; 252 // Stores whether during humongous object registration we found candidate regions. 253 // If not, we can skip a few steps. 254 bool _has_humongous_reclaim_candidates; 255 256 volatile uint _gc_time_stamp; 257 258 G1HRPrinter _hr_printer; 259 260 // It decides whether an explicit GC should start a concurrent cycle 261 // instead of doing a STW GC. Currently, a concurrent cycle is 262 // explicitly started if: 263 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 264 // (b) cause == _g1_humongous_allocation 265 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 266 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 267 // (e) cause == _update_allocation_context_stats_inc 268 // (f) cause == _wb_conc_mark 269 bool should_do_concurrent_full_gc(GCCause::Cause cause); 270 271 // indicates whether we are in young or mixed GC mode 272 G1CollectorState _collector_state; 273 274 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 275 // concurrent cycles) we have started. 276 volatile uint _old_marking_cycles_started; 277 278 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 279 // concurrent cycles) we have completed. 280 volatile uint _old_marking_cycles_completed; 281 282 // This is a non-product method that is helpful for testing. It is 283 // called at the end of a GC and artificially expands the heap by 284 // allocating a number of dead regions. This way we can induce very 285 // frequent marking cycles and stress the cleanup / concurrent 286 // cleanup code more (as all the regions that will be allocated by 287 // this method will be found dead by the marking cycle). 288 void allocate_dummy_regions() PRODUCT_RETURN; 289 290 // Clear RSets after a compaction. It also resets the GC time stamps. 291 void clear_rsets_post_compaction(); 292 293 // If the HR printer is active, dump the state of the regions in the 294 // heap after a compaction. 295 void print_hrm_post_compaction(); 296 297 // Create a memory mapper for auxiliary data structures of the given size and 298 // translation factor. 299 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 300 size_t size, 301 size_t translation_factor); 302 303 static G1Policy* create_g1_policy(STWGCTimer* gc_timer); 304 305 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 306 307 void process_weak_jni_handles(); 308 309 // These are macros so that, if the assert fires, we get the correct 310 // line number, file, etc. 311 312 #define heap_locking_asserts_params(_extra_message_) \ 313 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 314 (_extra_message_), \ 315 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 316 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 317 BOOL_TO_STR(Thread::current()->is_VM_thread()) 318 319 #define assert_heap_locked() \ 320 do { \ 321 assert(Heap_lock->owned_by_self(), \ 322 heap_locking_asserts_params("should be holding the Heap_lock")); \ 323 } while (0) 324 325 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 326 do { \ 327 assert(Heap_lock->owned_by_self() || \ 328 (SafepointSynchronize::is_at_safepoint() && \ 329 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 330 heap_locking_asserts_params("should be holding the Heap_lock or " \ 331 "should be at a safepoint")); \ 332 } while (0) 333 334 #define assert_heap_locked_and_not_at_safepoint() \ 335 do { \ 336 assert(Heap_lock->owned_by_self() && \ 337 !SafepointSynchronize::is_at_safepoint(), \ 338 heap_locking_asserts_params("should be holding the Heap_lock and " \ 339 "should not be at a safepoint")); \ 340 } while (0) 341 342 #define assert_heap_not_locked() \ 343 do { \ 344 assert(!Heap_lock->owned_by_self(), \ 345 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 346 } while (0) 347 348 #define assert_heap_not_locked_and_not_at_safepoint() \ 349 do { \ 350 assert(!Heap_lock->owned_by_self() && \ 351 !SafepointSynchronize::is_at_safepoint(), \ 352 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 353 "should not be at a safepoint")); \ 354 } while (0) 355 356 #define assert_at_safepoint(_should_be_vm_thread_) \ 357 do { \ 358 assert(SafepointSynchronize::is_at_safepoint() && \ 359 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 360 heap_locking_asserts_params("should be at a safepoint")); \ 361 } while (0) 362 363 #define assert_not_at_safepoint() \ 364 do { \ 365 assert(!SafepointSynchronize::is_at_safepoint(), \ 366 heap_locking_asserts_params("should not be at a safepoint")); \ 367 } while (0) 368 369 protected: 370 371 // The young region list. 372 G1EdenRegions _eden; 373 G1SurvivorRegions _survivor; 374 375 STWGCTimer* _gc_timer_stw; 376 377 G1NewTracer* _gc_tracer_stw; 378 379 // The current policy object for the collector. 380 G1Policy* _g1_policy; 381 G1HeapSizingPolicy* _heap_sizing_policy; 382 383 G1CollectionSet _collection_set; 384 385 // This is the second level of trying to allocate a new region. If 386 // new_region() didn't find a region on the free_list, this call will 387 // check whether there's anything available on the 388 // secondary_free_list and/or wait for more regions to appear on 389 // that list, if _free_regions_coming is set. 390 HeapRegion* new_region_try_secondary_free_list(bool is_old); 391 392 // Try to allocate a single non-humongous HeapRegion sufficient for 393 // an allocation of the given word_size. If do_expand is true, 394 // attempt to expand the heap if necessary to satisfy the allocation 395 // request. If the region is to be used as an old region or for a 396 // humongous object, set is_old to true. If not, to false. 397 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 398 399 // Initialize a contiguous set of free regions of length num_regions 400 // and starting at index first so that they appear as a single 401 // humongous region. 402 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 403 uint num_regions, 404 size_t word_size, 405 AllocationContext_t context); 406 407 // Attempt to allocate a humongous object of the given size. Return 408 // NULL if unsuccessful. 409 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 410 411 // The following two methods, allocate_new_tlab() and 412 // mem_allocate(), are the two main entry points from the runtime 413 // into the G1's allocation routines. They have the following 414 // assumptions: 415 // 416 // * They should both be called outside safepoints. 417 // 418 // * They should both be called without holding the Heap_lock. 419 // 420 // * All allocation requests for new TLABs should go to 421 // allocate_new_tlab(). 422 // 423 // * All non-TLAB allocation requests should go to mem_allocate(). 424 // 425 // * If either call cannot satisfy the allocation request using the 426 // current allocating region, they will try to get a new one. If 427 // this fails, they will attempt to do an evacuation pause and 428 // retry the allocation. 429 // 430 // * If all allocation attempts fail, even after trying to schedule 431 // an evacuation pause, allocate_new_tlab() will return NULL, 432 // whereas mem_allocate() will attempt a heap expansion and/or 433 // schedule a Full GC. 434 // 435 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 436 // should never be called with word_size being humongous. All 437 // humongous allocation requests should go to mem_allocate() which 438 // will satisfy them with a special path. 439 440 virtual HeapWord* allocate_new_tlab(size_t word_size); 441 442 virtual HeapWord* mem_allocate(size_t word_size, 443 bool* gc_overhead_limit_was_exceeded); 444 445 // The following three methods take a gc_count_before_ret 446 // parameter which is used to return the GC count if the method 447 // returns NULL. Given that we are required to read the GC count 448 // while holding the Heap_lock, and these paths will take the 449 // Heap_lock at some point, it's easier to get them to read the GC 450 // count while holding the Heap_lock before they return NULL instead 451 // of the caller (namely: mem_allocate()) having to also take the 452 // Heap_lock just to read the GC count. 453 454 // First-level mutator allocation attempt: try to allocate out of 455 // the mutator alloc region without taking the Heap_lock. This 456 // should only be used for non-humongous allocations. 457 inline HeapWord* attempt_allocation(size_t word_size, 458 uint* gc_count_before_ret, 459 uint* gclocker_retry_count_ret); 460 461 // Second-level mutator allocation attempt: take the Heap_lock and 462 // retry the allocation attempt, potentially scheduling a GC 463 // pause. This should only be used for non-humongous allocations. 464 HeapWord* attempt_allocation_slow(size_t word_size, 465 AllocationContext_t context, 466 uint* gc_count_before_ret, 467 uint* gclocker_retry_count_ret); 468 469 // Takes the Heap_lock and attempts a humongous allocation. It can 470 // potentially schedule a GC pause. 471 HeapWord* attempt_allocation_humongous(size_t word_size, 472 uint* gc_count_before_ret, 473 uint* gclocker_retry_count_ret); 474 475 // Allocation attempt that should be called during safepoints (e.g., 476 // at the end of a successful GC). expect_null_mutator_alloc_region 477 // specifies whether the mutator alloc region is expected to be NULL 478 // or not. 479 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 480 AllocationContext_t context, 481 bool expect_null_mutator_alloc_region); 482 483 // These methods are the "callbacks" from the G1AllocRegion class. 484 485 // For mutator alloc regions. 486 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 487 void retire_mutator_alloc_region(HeapRegion* alloc_region, 488 size_t allocated_bytes); 489 490 // For GC alloc regions. 491 bool has_more_regions(InCSetState dest); 492 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 493 void retire_gc_alloc_region(HeapRegion* alloc_region, 494 size_t allocated_bytes, InCSetState dest); 495 496 // - if explicit_gc is true, the GC is for a System.gc() etc, 497 // otherwise it's for a failed allocation. 498 // - if clear_all_soft_refs is true, all soft references should be 499 // cleared during the GC. 500 // - it returns false if it is unable to do the collection due to the 501 // GC locker being active, true otherwise. 502 bool do_full_collection(bool explicit_gc, 503 bool clear_all_soft_refs); 504 505 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 506 virtual void do_full_collection(bool clear_all_soft_refs); 507 508 // Resize the heap if necessary after a full collection. 509 void resize_if_necessary_after_full_collection(); 510 511 // Callback from VM_G1CollectForAllocation operation. 512 // This function does everything necessary/possible to satisfy a 513 // failed allocation request (including collection, expansion, etc.) 514 HeapWord* satisfy_failed_allocation(size_t word_size, 515 AllocationContext_t context, 516 bool* succeeded); 517 private: 518 // Internal helpers used during full GC to split it up to 519 // increase readability. 520 void do_full_collection_inner(G1FullGCScope* scope); 521 void abort_concurrent_cycle(); 522 void verify_before_full_collection(bool explicit_gc); 523 void prepare_heap_for_full_collection(); 524 void prepare_heap_for_mutators(); 525 void abort_refinement(); 526 void verify_after_full_collection(); 527 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 528 529 // Helper method for satisfy_failed_allocation() 530 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 531 AllocationContext_t context, 532 bool do_gc, 533 bool clear_all_soft_refs, 534 bool expect_null_mutator_alloc_region, 535 bool* gc_succeeded); 536 537 protected: 538 // Attempting to expand the heap sufficiently 539 // to support an allocation of the given "word_size". If 540 // successful, perform the allocation and return the address of the 541 // allocated block, or else "NULL". 542 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 543 544 // Preserve any referents discovered by concurrent marking that have not yet been 545 // copied by the STW pause. 546 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 547 // Process any reference objects discovered during 548 // an incremental evacuation pause. 549 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 550 551 // Enqueue any remaining discovered references 552 // after processing. 553 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 554 555 // Merges the information gathered on a per-thread basis for all worker threads 556 // during GC into global variables. 557 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 558 public: 559 WorkGang* workers() const { return _workers; } 560 561 G1Allocator* allocator() { 562 return _allocator; 563 } 564 565 G1HeapVerifier* verifier() { 566 return _verifier; 567 } 568 569 G1MonitoringSupport* g1mm() { 570 assert(_g1mm != NULL, "should have been initialized"); 571 return _g1mm; 572 } 573 574 // Expand the garbage-first heap by at least the given size (in bytes!). 575 // Returns true if the heap was expanded by the requested amount; 576 // false otherwise. 577 // (Rounds up to a HeapRegion boundary.) 578 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 579 580 // Returns the PLAB statistics for a given destination. 581 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 582 583 // Determines PLAB size for a given destination. 584 inline size_t desired_plab_sz(InCSetState dest); 585 586 inline AllocationContextStats& allocation_context_stats(); 587 588 // Do anything common to GC's. 589 void gc_prologue(bool full); 590 void gc_epilogue(bool full); 591 592 // Modify the reclaim candidate set and test for presence. 593 // These are only valid for starts_humongous regions. 594 inline void set_humongous_reclaim_candidate(uint region, bool value); 595 inline bool is_humongous_reclaim_candidate(uint region); 596 597 // Remove from the reclaim candidate set. Also remove from the 598 // collection set so that later encounters avoid the slow path. 599 inline void set_humongous_is_live(oop obj); 600 601 // Register the given region to be part of the collection set. 602 inline void register_humongous_region_with_cset(uint index); 603 // Register regions with humongous objects (actually on the start region) in 604 // the in_cset_fast_test table. 605 void register_humongous_regions_with_cset(); 606 // We register a region with the fast "in collection set" test. We 607 // simply set to true the array slot corresponding to this region. 608 void register_young_region_with_cset(HeapRegion* r) { 609 _in_cset_fast_test.set_in_young(r->hrm_index()); 610 } 611 void register_old_region_with_cset(HeapRegion* r) { 612 _in_cset_fast_test.set_in_old(r->hrm_index()); 613 } 614 inline void register_ext_region_with_cset(HeapRegion* r) { 615 _in_cset_fast_test.set_ext(r->hrm_index()); 616 } 617 void clear_in_cset(const HeapRegion* hr) { 618 _in_cset_fast_test.clear(hr); 619 } 620 621 void clear_cset_fast_test() { 622 _in_cset_fast_test.clear(); 623 } 624 625 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 626 627 // This is called at the start of either a concurrent cycle or a Full 628 // GC to update the number of old marking cycles started. 629 void increment_old_marking_cycles_started(); 630 631 // This is called at the end of either a concurrent cycle or a Full 632 // GC to update the number of old marking cycles completed. Those two 633 // can happen in a nested fashion, i.e., we start a concurrent 634 // cycle, a Full GC happens half-way through it which ends first, 635 // and then the cycle notices that a Full GC happened and ends 636 // too. The concurrent parameter is a boolean to help us do a bit 637 // tighter consistency checking in the method. If concurrent is 638 // false, the caller is the inner caller in the nesting (i.e., the 639 // Full GC). If concurrent is true, the caller is the outer caller 640 // in this nesting (i.e., the concurrent cycle). Further nesting is 641 // not currently supported. The end of this call also notifies 642 // the FullGCCount_lock in case a Java thread is waiting for a full 643 // GC to happen (e.g., it called System.gc() with 644 // +ExplicitGCInvokesConcurrent). 645 void increment_old_marking_cycles_completed(bool concurrent); 646 647 uint old_marking_cycles_completed() { 648 return _old_marking_cycles_completed; 649 } 650 651 G1HRPrinter* hr_printer() { return &_hr_printer; } 652 653 // Allocates a new heap region instance. 654 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 655 656 // Allocate the highest free region in the reserved heap. This will commit 657 // regions as necessary. 658 HeapRegion* alloc_highest_free_region(); 659 660 // Frees a non-humongous region by initializing its contents and 661 // adding it to the free list that's passed as a parameter (this is 662 // usually a local list which will be appended to the master free 663 // list later). The used bytes of freed regions are accumulated in 664 // pre_used. If skip_remset is true, the region's RSet will not be freed 665 // up. If skip_hot_card_cache is true, the region's hot card cache will not 666 // be freed up. The assumption is that this will be done later. 667 // The locked parameter indicates if the caller has already taken 668 // care of proper synchronization. This may allow some optimizations. 669 void free_region(HeapRegion* hr, 670 FreeRegionList* free_list, 671 bool skip_remset, 672 bool skip_hot_card_cache = false, 673 bool locked = false); 674 675 // It dirties the cards that cover the block so that the post 676 // write barrier never queues anything when updating objects on this 677 // block. It is assumed (and in fact we assert) that the block 678 // belongs to a young region. 679 inline void dirty_young_block(HeapWord* start, size_t word_size); 680 681 // Frees a humongous region by collapsing it into individual regions 682 // and calling free_region() for each of them. The freed regions 683 // will be added to the free list that's passed as a parameter (this 684 // is usually a local list which will be appended to the master free 685 // list later). The used bytes of freed regions are accumulated in 686 // pre_used. If skip_remset is true, the region's RSet will not be freed 687 // up. The assumption is that this will be done later. 688 void free_humongous_region(HeapRegion* hr, 689 FreeRegionList* free_list, 690 bool skip_remset); 691 692 // Facility for allocating in 'archive' regions in high heap memory and 693 // recording the allocated ranges. These should all be called from the 694 // VM thread at safepoints, without the heap lock held. They can be used 695 // to create and archive a set of heap regions which can be mapped at the 696 // same fixed addresses in a subsequent JVM invocation. 697 void begin_archive_alloc_range(bool open = false); 698 699 // Check if the requested size would be too large for an archive allocation. 700 bool is_archive_alloc_too_large(size_t word_size); 701 702 // Allocate memory of the requested size from the archive region. This will 703 // return NULL if the size is too large or if no memory is available. It 704 // does not trigger a garbage collection. 705 HeapWord* archive_mem_allocate(size_t word_size); 706 707 // Optionally aligns the end address and returns the allocated ranges in 708 // an array of MemRegions in order of ascending addresses. 709 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 710 size_t end_alignment_in_bytes = 0); 711 712 // Facility for allocating a fixed range within the heap and marking 713 // the containing regions as 'archive'. For use at JVM init time, when the 714 // caller may mmap archived heap data at the specified range(s). 715 // Verify that the MemRegions specified in the argument array are within the 716 // reserved heap. 717 bool check_archive_addresses(MemRegion* range, size_t count); 718 719 // Commit the appropriate G1 regions containing the specified MemRegions 720 // and mark them as 'archive' regions. The regions in the array must be 721 // non-overlapping and in order of ascending address. 722 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 723 724 // Insert any required filler objects in the G1 regions around the specified 725 // ranges to make the regions parseable. This must be called after 726 // alloc_archive_regions, and after class loading has occurred. 727 void fill_archive_regions(MemRegion* range, size_t count); 728 729 // For each of the specified MemRegions, uncommit the containing G1 regions 730 // which had been allocated by alloc_archive_regions. This should be called 731 // rather than fill_archive_regions at JVM init time if the archive file 732 // mapping failed, with the same non-overlapping and sorted MemRegion array. 733 void dealloc_archive_regions(MemRegion* range, size_t count); 734 735 protected: 736 737 // Shrink the garbage-first heap by at most the given size (in bytes!). 738 // (Rounds down to a HeapRegion boundary.) 739 virtual void shrink(size_t expand_bytes); 740 void shrink_helper(size_t expand_bytes); 741 742 #if TASKQUEUE_STATS 743 static void print_taskqueue_stats_hdr(outputStream* const st); 744 void print_taskqueue_stats() const; 745 void reset_taskqueue_stats(); 746 #endif // TASKQUEUE_STATS 747 748 // Schedule the VM operation that will do an evacuation pause to 749 // satisfy an allocation request of word_size. *succeeded will 750 // return whether the VM operation was successful (it did do an 751 // evacuation pause) or not (another thread beat us to it or the GC 752 // locker was active). Given that we should not be holding the 753 // Heap_lock when we enter this method, we will pass the 754 // gc_count_before (i.e., total_collections()) as a parameter since 755 // it has to be read while holding the Heap_lock. Currently, both 756 // methods that call do_collection_pause() release the Heap_lock 757 // before the call, so it's easy to read gc_count_before just before. 758 HeapWord* do_collection_pause(size_t word_size, 759 uint gc_count_before, 760 bool* succeeded, 761 GCCause::Cause gc_cause); 762 763 void wait_for_root_region_scanning(); 764 765 // The guts of the incremental collection pause, executed by the vm 766 // thread. It returns false if it is unable to do the collection due 767 // to the GC locker being active, true otherwise 768 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 769 770 // Actually do the work of evacuating the collection set. 771 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 772 773 void pre_evacuate_collection_set(); 774 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 775 776 // Print the header for the per-thread termination statistics. 777 static void print_termination_stats_hdr(); 778 // Print actual per-thread termination statistics. 779 void print_termination_stats(uint worker_id, 780 double elapsed_ms, 781 double strong_roots_ms, 782 double term_ms, 783 size_t term_attempts, 784 size_t alloc_buffer_waste, 785 size_t undo_waste) const; 786 // Update object copying statistics. 787 void record_obj_copy_mem_stats(); 788 789 // The hot card cache for remembered set insertion optimization. 790 G1HotCardCache* _hot_card_cache; 791 792 // The g1 remembered set of the heap. 793 G1RemSet* _g1_rem_set; 794 795 // A set of cards that cover the objects for which the Rsets should be updated 796 // concurrently after the collection. 797 DirtyCardQueueSet _dirty_card_queue_set; 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 // During reference object discovery, the _is_alive_non_header 922 // closure (if non-null) is applied to the referent object to 923 // determine whether the referent is live. If so then the 924 // reference object does not need to be 'discovered' and can 925 // be treated as a regular oop. This has the benefit of reducing 926 // the number of 'discovered' reference objects that need to 927 // be processed. 928 // 929 // Instance of the is_alive closure for embedding into the 930 // STW reference processor as the _is_alive_non_header field. 931 // Supplying a value for the _is_alive_non_header field is 932 // optional but doing so prevents unnecessary additions to 933 // the discovered lists during reference discovery. 934 G1STWIsAliveClosure _is_alive_closure_stw; 935 936 // The (concurrent marking) reference processor... 937 ReferenceProcessor* _ref_processor_cm; 938 939 // Instance of the concurrent mark is_alive closure for embedding 940 // into the Concurrent Marking reference processor as the 941 // _is_alive_non_header field. Supplying a value for the 942 // _is_alive_non_header field is optional but doing so prevents 943 // unnecessary additions to the discovered lists during reference 944 // discovery. 945 G1CMIsAliveClosure _is_alive_closure_cm; 946 947 volatile bool _free_regions_coming; 948 949 public: 950 951 RefToScanQueue *task_queue(uint i) const; 952 953 uint num_task_queues() const; 954 955 // A set of cards where updates happened during the GC 956 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 957 958 // Create a G1CollectedHeap with the specified policy. 959 // Must call the initialize method afterwards. 960 // May not return if something goes wrong. 961 G1CollectedHeap(G1CollectorPolicy* policy); 962 963 private: 964 jint initialize_concurrent_refinement(); 965 public: 966 // Initialize the G1CollectedHeap to have the initial and 967 // maximum sizes and remembered and barrier sets 968 // specified by the policy object. 969 jint initialize(); 970 971 virtual void stop(); 972 973 // Return the (conservative) maximum heap alignment for any G1 heap 974 static size_t conservative_max_heap_alignment(); 975 976 // Does operations required after initialization has been done. 977 void post_initialize(); 978 979 // Initialize weak reference processing. 980 void ref_processing_init(); 981 982 virtual Name kind() const { 983 return CollectedHeap::G1CollectedHeap; 984 } 985 986 virtual const char* name() const { 987 return "G1"; 988 } 989 990 const G1CollectorState* collector_state() const { return &_collector_state; } 991 G1CollectorState* collector_state() { return &_collector_state; } 992 993 // The current policy object for the collector. 994 G1Policy* g1_policy() const { return _g1_policy; } 995 996 const G1CollectionSet* collection_set() const { return &_collection_set; } 997 G1CollectionSet* collection_set() { return &_collection_set; } 998 999 virtual CollectorPolicy* collector_policy() const; 1000 1001 // Adaptive size policy. No such thing for g1. 1002 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1003 1004 // The rem set and barrier set. 1005 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1006 1007 // Try to minimize the remembered set. 1008 void scrub_rem_set(); 1009 1010 uint get_gc_time_stamp() { 1011 return _gc_time_stamp; 1012 } 1013 1014 inline void reset_gc_time_stamp(); 1015 1016 void check_gc_time_stamps() PRODUCT_RETURN; 1017 1018 inline void increment_gc_time_stamp(); 1019 1020 // Reset the given region's GC timestamp. If it's starts humongous, 1021 // also reset the GC timestamp of its corresponding 1022 // continues humongous regions too. 1023 void reset_gc_time_stamps(HeapRegion* hr); 1024 1025 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1026 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1027 1028 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1029 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1030 1031 // The shared block offset table array. 1032 G1BlockOffsetTable* bot() const { return _bot; } 1033 1034 // Reference Processing accessors 1035 1036 // The STW reference processor.... 1037 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1038 1039 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1040 1041 // The Concurrent Marking reference processor... 1042 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1043 1044 virtual size_t capacity() const; 1045 virtual size_t used() const; 1046 // This should be called when we're not holding the heap lock. The 1047 // result might be a bit inaccurate. 1048 size_t used_unlocked() const; 1049 size_t recalculate_used() const; 1050 1051 // These virtual functions do the actual allocation. 1052 // Some heaps may offer a contiguous region for shared non-blocking 1053 // allocation, via inlined code (by exporting the address of the top and 1054 // end fields defining the extent of the contiguous allocation region.) 1055 // But G1CollectedHeap doesn't yet support this. 1056 1057 virtual bool is_maximal_no_gc() const { 1058 return _hrm.available() == 0; 1059 } 1060 1061 // The current number of regions in the heap. 1062 uint num_regions() const { return _hrm.length(); } 1063 1064 // The max number of regions in the heap. 1065 uint max_regions() const { return _hrm.max_length(); } 1066 1067 // The number of regions that are completely free. 1068 uint num_free_regions() const { return _hrm.num_free_regions(); } 1069 1070 MemoryUsage get_auxiliary_data_memory_usage() const { 1071 return _hrm.get_auxiliary_data_memory_usage(); 1072 } 1073 1074 // The number of regions that are not completely free. 1075 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1076 1077 #ifdef ASSERT 1078 bool is_on_master_free_list(HeapRegion* hr) { 1079 return _hrm.is_free(hr); 1080 } 1081 #endif // ASSERT 1082 1083 // Wrapper for the region list operations that can be called from 1084 // methods outside this class. 1085 1086 void secondary_free_list_add(FreeRegionList* list) { 1087 _secondary_free_list.add_ordered(list); 1088 } 1089 1090 void append_secondary_free_list() { 1091 _hrm.insert_list_into_free_list(&_secondary_free_list); 1092 } 1093 1094 void append_secondary_free_list_if_not_empty_with_lock() { 1095 // If the secondary free list looks empty there's no reason to 1096 // take the lock and then try to append it. 1097 if (!_secondary_free_list.is_empty()) { 1098 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1099 append_secondary_free_list(); 1100 } 1101 } 1102 1103 inline void old_set_add(HeapRegion* hr); 1104 inline void old_set_remove(HeapRegion* hr); 1105 1106 size_t non_young_capacity_bytes() { 1107 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1108 } 1109 1110 void set_free_regions_coming(); 1111 void reset_free_regions_coming(); 1112 bool free_regions_coming() { return _free_regions_coming; } 1113 void wait_while_free_regions_coming(); 1114 1115 // Determine whether the given region is one that we are using as an 1116 // old GC alloc region. 1117 bool is_old_gc_alloc_region(HeapRegion* hr); 1118 1119 // Perform a collection of the heap; intended for use in implementing 1120 // "System.gc". This probably implies as full a collection as the 1121 // "CollectedHeap" supports. 1122 virtual void collect(GCCause::Cause cause); 1123 1124 virtual bool copy_allocation_context_stats(const jint* contexts, 1125 jlong* totals, 1126 jbyte* accuracy, 1127 jint len); 1128 1129 // True iff an evacuation has failed in the most-recent collection. 1130 bool evacuation_failed() { return _evacuation_failed; } 1131 1132 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1133 void prepend_to_freelist(FreeRegionList* list); 1134 void decrement_summary_bytes(size_t bytes); 1135 1136 virtual bool is_in(const void* p) const; 1137 #ifdef ASSERT 1138 // Returns whether p is in one of the available areas of the heap. Slow but 1139 // extensive version. 1140 bool is_in_exact(const void* p) const; 1141 #endif 1142 1143 // Return "TRUE" iff the given object address is within the collection 1144 // set. Assumes that the reference points into the heap. 1145 inline bool is_in_cset(const HeapRegion *hr); 1146 inline bool is_in_cset(oop obj); 1147 inline bool is_in_cset(HeapWord* addr); 1148 1149 inline bool is_in_cset_or_humongous(const oop obj); 1150 1151 private: 1152 // This array is used for a quick test on whether a reference points into 1153 // the collection set or not. Each of the array's elements denotes whether the 1154 // corresponding region is in the collection set or not. 1155 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1156 1157 public: 1158 1159 inline InCSetState in_cset_state(const oop obj); 1160 1161 // Return "TRUE" iff the given object address is in the reserved 1162 // region of g1. 1163 bool is_in_g1_reserved(const void* p) const { 1164 return _hrm.reserved().contains(p); 1165 } 1166 1167 // Returns a MemRegion that corresponds to the space that has been 1168 // reserved for the heap 1169 MemRegion g1_reserved() const { 1170 return _hrm.reserved(); 1171 } 1172 1173 virtual bool is_in_closed_subset(const void* p) const; 1174 1175 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1176 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1177 } 1178 1179 // Iteration functions. 1180 1181 // Iterate over all objects, calling "cl.do_object" on each. 1182 virtual void object_iterate(ObjectClosure* cl); 1183 1184 virtual void safe_object_iterate(ObjectClosure* cl) { 1185 object_iterate(cl); 1186 } 1187 1188 // Iterate over heap regions, in address order, terminating the 1189 // iteration early if the "doHeapRegion" method returns "true". 1190 void heap_region_iterate(HeapRegionClosure* blk) const; 1191 1192 // Return the region with the given index. It assumes the index is valid. 1193 inline HeapRegion* region_at(uint index) const; 1194 1195 // Return the next region (by index) that is part of the same 1196 // humongous object that hr is part of. 1197 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1198 1199 // Calculate the region index of the given address. Given address must be 1200 // within the heap. 1201 inline uint addr_to_region(HeapWord* addr) const; 1202 1203 inline HeapWord* bottom_addr_for_region(uint index) const; 1204 1205 // Iterate over the heap regions in parallel. Assumes that this will be called 1206 // in parallel by a number of worker threads with distinct worker ids 1207 // in the range passed to the HeapRegionClaimer. Applies "blk->doHeapRegion" 1208 // to each of the regions, by attempting to claim the region using the 1209 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1210 // region. 1211 void heap_region_par_iterate(HeapRegionClosure* cl, 1212 uint worker_id, 1213 HeapRegionClaimer* hrclaimer) const; 1214 1215 // Iterate over the regions (if any) in the current collection set. 1216 void collection_set_iterate(HeapRegionClosure* blk); 1217 1218 // Iterate over the regions (if any) in the current collection set. Starts the 1219 // iteration over the entire collection set so that the start regions of a given 1220 // worker id over the set active_workers are evenly spread across the set of 1221 // collection set regions. 1222 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1223 1224 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1225 1226 // Returns the HeapRegion that contains addr. addr must not be NULL. 1227 template <class T> 1228 inline HeapRegion* heap_region_containing(const T addr) const; 1229 1230 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1231 // each address in the (reserved) heap is a member of exactly 1232 // one block. The defining characteristic of a block is that it is 1233 // possible to find its size, and thus to progress forward to the next 1234 // block. (Blocks may be of different sizes.) Thus, blocks may 1235 // represent Java objects, or they might be free blocks in a 1236 // free-list-based heap (or subheap), as long as the two kinds are 1237 // distinguishable and the size of each is determinable. 1238 1239 // Returns the address of the start of the "block" that contains the 1240 // address "addr". We say "blocks" instead of "object" since some heaps 1241 // may not pack objects densely; a chunk may either be an object or a 1242 // non-object. 1243 virtual HeapWord* block_start(const void* addr) const; 1244 1245 // Requires "addr" to be the start of a chunk, and returns its size. 1246 // "addr + size" is required to be the start of a new chunk, or the end 1247 // of the active area of the heap. 1248 virtual size_t block_size(const HeapWord* addr) const; 1249 1250 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1251 // the block is an object. 1252 virtual bool block_is_obj(const HeapWord* addr) const; 1253 1254 // Section on thread-local allocation buffers (TLABs) 1255 // See CollectedHeap for semantics. 1256 1257 bool supports_tlab_allocation() const; 1258 size_t tlab_capacity(Thread* ignored) const; 1259 size_t tlab_used(Thread* ignored) const; 1260 size_t max_tlab_size() const; 1261 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1262 1263 // Can a compiler initialize a new object without store barriers? 1264 // This permission only extends from the creation of a new object 1265 // via a TLAB up to the first subsequent safepoint. If such permission 1266 // is granted for this heap type, the compiler promises to call 1267 // defer_store_barrier() below on any slow path allocation of 1268 // a new object for which such initializing store barriers will 1269 // have been elided. G1, like CMS, allows this, but should be 1270 // ready to provide a compensating write barrier as necessary 1271 // if that storage came out of a non-young region. The efficiency 1272 // of this implementation depends crucially on being able to 1273 // answer very efficiently in constant time whether a piece of 1274 // storage in the heap comes from a young region or not. 1275 // See ReduceInitialCardMarks. 1276 virtual bool can_elide_tlab_store_barriers() const { 1277 return true; 1278 } 1279 1280 virtual bool card_mark_must_follow_store() const { 1281 return true; 1282 } 1283 1284 inline bool is_in_young(const oop obj); 1285 1286 virtual bool is_scavengable(const void* addr); 1287 1288 // We don't need barriers for initializing stores to objects 1289 // in the young gen: for the SATB pre-barrier, there is no 1290 // pre-value that needs to be remembered; for the remembered-set 1291 // update logging post-barrier, we don't maintain remembered set 1292 // information for young gen objects. 1293 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1294 1295 // Returns "true" iff the given word_size is "very large". 1296 static bool is_humongous(size_t word_size) { 1297 // Note this has to be strictly greater-than as the TLABs 1298 // are capped at the humongous threshold and we want to 1299 // ensure that we don't try to allocate a TLAB as 1300 // humongous and that we don't allocate a humongous 1301 // object in a TLAB. 1302 return word_size > _humongous_object_threshold_in_words; 1303 } 1304 1305 // Returns the humongous threshold for a specific region size 1306 static size_t humongous_threshold_for(size_t region_size) { 1307 return (region_size / 2); 1308 } 1309 1310 // Returns the number of regions the humongous object of the given word size 1311 // requires. 1312 static size_t humongous_obj_size_in_regions(size_t word_size); 1313 1314 // Print the maximum heap capacity. 1315 virtual size_t max_capacity() const; 1316 1317 virtual jlong millis_since_last_gc(); 1318 1319 1320 // Convenience function to be used in situations where the heap type can be 1321 // asserted to be this type. 1322 static G1CollectedHeap* heap(); 1323 1324 void set_region_short_lived_locked(HeapRegion* hr); 1325 // add appropriate methods for any other surv rate groups 1326 1327 const G1SurvivorRegions* survivor() const { return &_survivor; } 1328 1329 uint survivor_regions_count() const { 1330 return _survivor.length(); 1331 } 1332 1333 uint eden_regions_count() const { 1334 return _eden.length(); 1335 } 1336 1337 uint young_regions_count() const { 1338 return _eden.length() + _survivor.length(); 1339 } 1340 1341 uint old_regions_count() const { return _old_set.length(); } 1342 1343 uint humongous_regions_count() const { return _humongous_set.length(); } 1344 1345 #ifdef ASSERT 1346 bool check_young_list_empty(); 1347 #endif 1348 1349 // *** Stuff related to concurrent marking. It's not clear to me that so 1350 // many of these need to be public. 1351 1352 // The functions below are helper functions that a subclass of 1353 // "CollectedHeap" can use in the implementation of its virtual 1354 // functions. 1355 // This performs a concurrent marking of the live objects in a 1356 // bitmap off to the side. 1357 void doConcurrentMark(); 1358 1359 bool isMarkedNext(oop obj) const; 1360 1361 // Determine if an object is dead, given the object and also 1362 // the region to which the object belongs. An object is dead 1363 // iff a) it was not allocated since the last mark, b) it 1364 // is not marked, and c) it is not in an archive region. 1365 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1366 return 1367 hr->is_obj_dead(obj, _cm->prevMarkBitMap()) && 1368 !hr->is_archive(); 1369 } 1370 1371 // This function returns true when an object has been 1372 // around since the previous marking and hasn't yet 1373 // been marked during this marking, and is not in an archive region. 1374 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1375 return 1376 !hr->obj_allocated_since_next_marking(obj) && 1377 !isMarkedNext(obj) && 1378 !hr->is_archive(); 1379 } 1380 1381 // Determine if an object is dead, given only the object itself. 1382 // This will find the region to which the object belongs and 1383 // then call the region version of the same function. 1384 1385 // Added if it is NULL it isn't dead. 1386 1387 inline bool is_obj_dead(const oop obj) const; 1388 1389 inline bool is_obj_ill(const oop obj) const; 1390 1391 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1392 1393 // Refinement 1394 1395 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1396 1397 // Optimized nmethod scanning support routines 1398 1399 // Register the given nmethod with the G1 heap. 1400 virtual void register_nmethod(nmethod* nm); 1401 1402 // Unregister the given nmethod from the G1 heap. 1403 virtual void unregister_nmethod(nmethod* nm); 1404 1405 // Free up superfluous code root memory. 1406 void purge_code_root_memory(); 1407 1408 // Rebuild the strong code root lists for each region 1409 // after a full GC. 1410 void rebuild_strong_code_roots(); 1411 1412 // Partial cleaning used when class unloading is disabled. 1413 // Let the caller choose what structures to clean out: 1414 // - StringTable 1415 // - SymbolTable 1416 // - StringDeduplication structures 1417 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1418 1419 // Complete cleaning used when class unloading is enabled. 1420 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1421 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1422 1423 // Redirty logged cards in the refinement queue. 1424 void redirty_logged_cards(); 1425 // Verification 1426 1427 // Perform any cleanup actions necessary before allowing a verification. 1428 virtual void prepare_for_verify(); 1429 1430 // Perform verification. 1431 1432 // vo == UsePrevMarking -> use "prev" marking information, 1433 // vo == UseNextMarking -> use "next" marking information 1434 // vo == UseMarkWord -> use the mark word in the object header 1435 // 1436 // NOTE: Only the "prev" marking information is guaranteed to be 1437 // consistent most of the time, so most calls to this should use 1438 // vo == UsePrevMarking. 1439 // Currently, there is only one case where this is called with 1440 // vo == UseNextMarking, which is to verify the "next" marking 1441 // information at the end of remark. 1442 // Currently there is only one place where this is called with 1443 // vo == UseMarkWord, which is to verify the marking during a 1444 // full GC. 1445 void verify(VerifyOption vo); 1446 1447 // WhiteBox testing support. 1448 virtual bool supports_concurrent_phase_control() const; 1449 virtual const char* const* concurrent_phases() const; 1450 virtual bool request_concurrent_phase(const char* phase); 1451 1452 // The methods below are here for convenience and dispatch the 1453 // appropriate method depending on value of the given VerifyOption 1454 // parameter. The values for that parameter, and their meanings, 1455 // are the same as those above. 1456 1457 bool is_obj_dead_cond(const oop obj, 1458 const HeapRegion* hr, 1459 const VerifyOption vo) const; 1460 1461 bool is_obj_dead_cond(const oop obj, 1462 const VerifyOption vo) const; 1463 1464 G1HeapSummary create_g1_heap_summary(); 1465 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1466 1467 // Printing 1468 private: 1469 void print_heap_regions() const; 1470 void print_regions_on(outputStream* st) const; 1471 1472 public: 1473 virtual void print_on(outputStream* st) const; 1474 virtual void print_extended_on(outputStream* st) const; 1475 virtual void print_on_error(outputStream* st) const; 1476 1477 virtual void print_gc_threads_on(outputStream* st) const; 1478 virtual void gc_threads_do(ThreadClosure* tc) const; 1479 1480 // Override 1481 void print_tracing_info() const; 1482 1483 // The following two methods are helpful for debugging RSet issues. 1484 void print_cset_rsets() PRODUCT_RETURN; 1485 void print_all_rsets() PRODUCT_RETURN; 1486 1487 public: 1488 size_t pending_card_num(); 1489 1490 protected: 1491 size_t _max_heap_capacity; 1492 }; 1493 1494 class G1ParEvacuateFollowersClosure : public VoidClosure { 1495 private: 1496 double _start_term; 1497 double _term_time; 1498 size_t _term_attempts; 1499 1500 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1501 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1502 protected: 1503 G1CollectedHeap* _g1h; 1504 G1ParScanThreadState* _par_scan_state; 1505 RefToScanQueueSet* _queues; 1506 ParallelTaskTerminator* _terminator; 1507 1508 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1509 RefToScanQueueSet* queues() { return _queues; } 1510 ParallelTaskTerminator* terminator() { return _terminator; } 1511 1512 public: 1513 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1514 G1ParScanThreadState* par_scan_state, 1515 RefToScanQueueSet* queues, 1516 ParallelTaskTerminator* terminator) 1517 : _g1h(g1h), _par_scan_state(par_scan_state), 1518 _queues(queues), _terminator(terminator), 1519 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1520 1521 void do_void(); 1522 1523 double term_time() const { return _term_time; } 1524 size_t term_attempts() const { return _term_attempts; } 1525 1526 private: 1527 inline bool offer_termination(); 1528 }; 1529 1530 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP