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 HeapRegionClaimerBase; 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(); 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 // The current policy object for the collector. 376 G1Policy* _g1_policy; 377 G1HeapSizingPolicy* _heap_sizing_policy; 378 379 G1CollectionSet _collection_set; 380 381 // This is the second level of trying to allocate a new region. If 382 // new_region() didn't find a region on the free_list, this call will 383 // check whether there's anything available on the 384 // secondary_free_list and/or wait for more regions to appear on 385 // that list, if _free_regions_coming is set. 386 HeapRegion* new_region_try_secondary_free_list(bool is_old); 387 388 // Try to allocate a single non-humongous HeapRegion sufficient for 389 // an allocation of the given word_size. If do_expand is true, 390 // attempt to expand the heap if necessary to satisfy the allocation 391 // request. If the region is to be used as an old region or for a 392 // humongous object, set is_old to true. If not, to false. 393 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 394 395 // Initialize a contiguous set of free regions of length num_regions 396 // and starting at index first so that they appear as a single 397 // humongous region. 398 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 399 uint num_regions, 400 size_t word_size, 401 AllocationContext_t context); 402 403 // Attempt to allocate a humongous object of the given size. Return 404 // NULL if unsuccessful. 405 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 406 407 // The following two methods, allocate_new_tlab() and 408 // mem_allocate(), are the two main entry points from the runtime 409 // into the G1's allocation routines. They have the following 410 // assumptions: 411 // 412 // * They should both be called outside safepoints. 413 // 414 // * They should both be called without holding the Heap_lock. 415 // 416 // * All allocation requests for new TLABs should go to 417 // allocate_new_tlab(). 418 // 419 // * All non-TLAB allocation requests should go to mem_allocate(). 420 // 421 // * If either call cannot satisfy the allocation request using the 422 // current allocating region, they will try to get a new one. If 423 // this fails, they will attempt to do an evacuation pause and 424 // retry the allocation. 425 // 426 // * If all allocation attempts fail, even after trying to schedule 427 // an evacuation pause, allocate_new_tlab() will return NULL, 428 // whereas mem_allocate() will attempt a heap expansion and/or 429 // schedule a Full GC. 430 // 431 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 432 // should never be called with word_size being humongous. All 433 // humongous allocation requests should go to mem_allocate() which 434 // will satisfy them with a special path. 435 436 virtual HeapWord* allocate_new_tlab(size_t word_size); 437 438 virtual HeapWord* mem_allocate(size_t word_size, 439 bool* gc_overhead_limit_was_exceeded); 440 441 // The following three methods take a gc_count_before_ret 442 // parameter which is used to return the GC count if the method 443 // returns NULL. Given that we are required to read the GC count 444 // while holding the Heap_lock, and these paths will take the 445 // Heap_lock at some point, it's easier to get them to read the GC 446 // count while holding the Heap_lock before they return NULL instead 447 // of the caller (namely: mem_allocate()) having to also take the 448 // Heap_lock just to read the GC count. 449 450 // First-level mutator allocation attempt: try to allocate out of 451 // the mutator alloc region without taking the Heap_lock. This 452 // should only be used for non-humongous allocations. 453 inline HeapWord* attempt_allocation(size_t word_size, 454 uint* gc_count_before_ret, 455 uint* gclocker_retry_count_ret); 456 457 // Second-level mutator allocation attempt: take the Heap_lock and 458 // retry the allocation attempt, potentially scheduling a GC 459 // pause. This should only be used for non-humongous allocations. 460 HeapWord* attempt_allocation_slow(size_t word_size, 461 AllocationContext_t context, 462 uint* gc_count_before_ret, 463 uint* gclocker_retry_count_ret); 464 465 // Takes the Heap_lock and attempts a humongous allocation. It can 466 // potentially schedule a GC pause. 467 HeapWord* attempt_allocation_humongous(size_t word_size, 468 uint* gc_count_before_ret, 469 uint* gclocker_retry_count_ret); 470 471 // Allocation attempt that should be called during safepoints (e.g., 472 // at the end of a successful GC). expect_null_mutator_alloc_region 473 // specifies whether the mutator alloc region is expected to be NULL 474 // or not. 475 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 476 AllocationContext_t context, 477 bool expect_null_mutator_alloc_region); 478 479 // These methods are the "callbacks" from the G1AllocRegion class. 480 481 // For mutator alloc regions. 482 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 483 void retire_mutator_alloc_region(HeapRegion* alloc_region, 484 size_t allocated_bytes); 485 486 // For GC alloc regions. 487 bool has_more_regions(InCSetState dest); 488 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 489 void retire_gc_alloc_region(HeapRegion* alloc_region, 490 size_t allocated_bytes, InCSetState dest); 491 492 // - if explicit_gc is true, the GC is for a System.gc() etc, 493 // otherwise it's for a failed allocation. 494 // - if clear_all_soft_refs is true, all soft references should be 495 // cleared during the GC. 496 // - it returns false if it is unable to do the collection due to the 497 // GC locker being active, true otherwise. 498 bool do_full_collection(bool explicit_gc, 499 bool clear_all_soft_refs); 500 501 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 502 virtual void do_full_collection(bool clear_all_soft_refs); 503 504 // Resize the heap if necessary after a full collection. 505 void resize_if_necessary_after_full_collection(); 506 507 // Callback from VM_G1CollectForAllocation operation. 508 // This function does everything necessary/possible to satisfy a 509 // failed allocation request (including collection, expansion, etc.) 510 HeapWord* satisfy_failed_allocation(size_t word_size, 511 AllocationContext_t context, 512 bool* succeeded); 513 private: 514 // Internal helpers used during full GC to split it up to 515 // increase readability. 516 void do_full_collection_inner(G1FullGCScope* scope); 517 void abort_concurrent_cycle(); 518 void verify_before_full_collection(bool explicit_gc); 519 void prepare_heap_for_full_collection(); 520 void prepare_heap_for_mutators(); 521 void abort_refinement(); 522 void verify_after_full_collection(); 523 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 524 525 // Helper method for satisfy_failed_allocation() 526 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 527 AllocationContext_t context, 528 bool do_gc, 529 bool clear_all_soft_refs, 530 bool expect_null_mutator_alloc_region, 531 bool* gc_succeeded); 532 533 protected: 534 // Attempting to expand the heap sufficiently 535 // to support an allocation of the given "word_size". If 536 // successful, perform the allocation and return the address of the 537 // allocated block, or else "NULL". 538 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 539 540 // Preserve any referents discovered by concurrent marking that have not yet been 541 // copied by the STW pause. 542 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 543 // Process any reference objects discovered during 544 // an incremental evacuation pause. 545 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 546 547 // Enqueue any remaining discovered references 548 // after processing. 549 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 550 551 // Merges the information gathered on a per-thread basis for all worker threads 552 // during GC into global variables. 553 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 554 public: 555 WorkGang* workers() const { return _workers; } 556 557 G1Allocator* allocator() { 558 return _allocator; 559 } 560 561 G1HeapVerifier* verifier() { 562 return _verifier; 563 } 564 565 G1MonitoringSupport* g1mm() { 566 assert(_g1mm != NULL, "should have been initialized"); 567 return _g1mm; 568 } 569 570 // Expand the garbage-first heap by at least the given size (in bytes!). 571 // Returns true if the heap was expanded by the requested amount; 572 // false otherwise. 573 // (Rounds up to a HeapRegion boundary.) 574 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 575 576 // Returns the PLAB statistics for a given destination. 577 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 578 579 // Determines PLAB size for a given destination. 580 inline size_t desired_plab_sz(InCSetState dest); 581 582 inline AllocationContextStats& allocation_context_stats(); 583 584 // Do anything common to GC's. 585 void gc_prologue(bool full); 586 void gc_epilogue(bool full); 587 588 // Modify the reclaim candidate set and test for presence. 589 // These are only valid for starts_humongous regions. 590 inline void set_humongous_reclaim_candidate(uint region, bool value); 591 inline bool is_humongous_reclaim_candidate(uint region); 592 593 // Remove from the reclaim candidate set. Also remove from the 594 // collection set so that later encounters avoid the slow path. 595 inline void set_humongous_is_live(oop obj); 596 597 // Register the given region to be part of the collection set. 598 inline void register_humongous_region_with_cset(uint index); 599 // Register regions with humongous objects (actually on the start region) in 600 // the in_cset_fast_test table. 601 void register_humongous_regions_with_cset(); 602 // We register a region with the fast "in collection set" test. We 603 // simply set to true the array slot corresponding to this region. 604 void register_young_region_with_cset(HeapRegion* r) { 605 _in_cset_fast_test.set_in_young(r->hrm_index()); 606 } 607 void register_old_region_with_cset(HeapRegion* r) { 608 _in_cset_fast_test.set_in_old(r->hrm_index()); 609 } 610 inline void register_ext_region_with_cset(HeapRegion* r) { 611 _in_cset_fast_test.set_ext(r->hrm_index()); 612 } 613 void clear_in_cset(const HeapRegion* hr) { 614 _in_cset_fast_test.clear(hr); 615 } 616 617 void clear_cset_fast_test() { 618 _in_cset_fast_test.clear(); 619 } 620 621 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 622 623 // This is called at the start of either a concurrent cycle or a Full 624 // GC to update the number of old marking cycles started. 625 void increment_old_marking_cycles_started(); 626 627 // This is called at the end of either a concurrent cycle or a Full 628 // GC to update the number of old marking cycles completed. Those two 629 // can happen in a nested fashion, i.e., we start a concurrent 630 // cycle, a Full GC happens half-way through it which ends first, 631 // and then the cycle notices that a Full GC happened and ends 632 // too. The concurrent parameter is a boolean to help us do a bit 633 // tighter consistency checking in the method. If concurrent is 634 // false, the caller is the inner caller in the nesting (i.e., the 635 // Full GC). If concurrent is true, the caller is the outer caller 636 // in this nesting (i.e., the concurrent cycle). Further nesting is 637 // not currently supported. The end of this call also notifies 638 // the FullGCCount_lock in case a Java thread is waiting for a full 639 // GC to happen (e.g., it called System.gc() with 640 // +ExplicitGCInvokesConcurrent). 641 void increment_old_marking_cycles_completed(bool concurrent); 642 643 uint old_marking_cycles_completed() { 644 return _old_marking_cycles_completed; 645 } 646 647 G1HRPrinter* hr_printer() { return &_hr_printer; } 648 649 // Allocates a new heap region instance. 650 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 651 652 // Allocate the highest free region in the reserved heap. This will commit 653 // regions as necessary. 654 HeapRegion* alloc_highest_free_region(); 655 656 // Frees a non-humongous region by initializing its contents and 657 // adding it to the free list that's passed as a parameter (this is 658 // usually a local list which will be appended to the master free 659 // list later). The used bytes of freed regions are accumulated in 660 // pre_used. If skip_remset is true, the region's RSet will not be freed 661 // up. If skip_hot_card_cache is true, the region's hot card cache will not 662 // be freed up. The assumption is that this will be done later. 663 // The locked parameter indicates if the caller has already taken 664 // care of proper synchronization. This may allow some optimizations. 665 void free_region(HeapRegion* hr, 666 FreeRegionList* free_list, 667 bool skip_remset, 668 bool skip_hot_card_cache = false, 669 bool locked = false); 670 671 // It dirties the cards that cover the block so that the post 672 // write barrier never queues anything when updating objects on this 673 // block. It is assumed (and in fact we assert) that the block 674 // belongs to a young region. 675 inline void dirty_young_block(HeapWord* start, size_t word_size); 676 677 // Frees a humongous region by collapsing it into individual regions 678 // and calling free_region() for each of them. The freed regions 679 // will be added to the free list that's passed as a parameter (this 680 // is usually a local list which will be appended to the master free 681 // list later). The used bytes of freed regions are accumulated in 682 // pre_used. If skip_remset is true, the region's RSet will not be freed 683 // up. The assumption is that this will be done later. 684 void free_humongous_region(HeapRegion* hr, 685 FreeRegionList* free_list, 686 bool skip_remset); 687 688 // Facility for allocating in 'archive' regions in high heap memory and 689 // recording the allocated ranges. These should all be called from the 690 // VM thread at safepoints, without the heap lock held. They can be used 691 // to create and archive a set of heap regions which can be mapped at the 692 // same fixed addresses in a subsequent JVM invocation. 693 void begin_archive_alloc_range(); 694 695 // Check if the requested size would be too large for an archive allocation. 696 bool is_archive_alloc_too_large(size_t word_size); 697 698 // Allocate memory of the requested size from the archive region. This will 699 // return NULL if the size is too large or if no memory is available. It 700 // does not trigger a garbage collection. 701 HeapWord* archive_mem_allocate(size_t word_size); 702 703 // Optionally aligns the end address and returns the allocated ranges in 704 // an array of MemRegions in order of ascending addresses. 705 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 706 size_t end_alignment_in_bytes = 0); 707 708 // Facility for allocating a fixed range within the heap and marking 709 // the containing regions as 'archive'. For use at JVM init time, when the 710 // caller may mmap archived heap data at the specified range(s). 711 // Verify that the MemRegions specified in the argument array are within the 712 // reserved heap. 713 bool check_archive_addresses(MemRegion* range, size_t count); 714 715 // Commit the appropriate G1 regions containing the specified MemRegions 716 // and mark them as 'archive' regions. The regions in the array must be 717 // non-overlapping and in order of ascending address. 718 bool alloc_archive_regions(MemRegion* range, size_t count); 719 720 // Insert any required filler objects in the G1 regions around the specified 721 // ranges to make the regions parseable. This must be called after 722 // alloc_archive_regions, and after class loading has occurred. 723 void fill_archive_regions(MemRegion* range, size_t count); 724 725 // For each of the specified MemRegions, uncommit the containing G1 regions 726 // which had been allocated by alloc_archive_regions. This should be called 727 // rather than fill_archive_regions at JVM init time if the archive file 728 // mapping failed, with the same non-overlapping and sorted MemRegion array. 729 void dealloc_archive_regions(MemRegion* range, size_t count); 730 731 protected: 732 733 // Shrink the garbage-first heap by at most the given size (in bytes!). 734 // (Rounds down to a HeapRegion boundary.) 735 virtual void shrink(size_t expand_bytes); 736 void shrink_helper(size_t expand_bytes); 737 738 #if TASKQUEUE_STATS 739 static void print_taskqueue_stats_hdr(outputStream* const st); 740 void print_taskqueue_stats() const; 741 void reset_taskqueue_stats(); 742 #endif // TASKQUEUE_STATS 743 744 // Schedule the VM operation that will do an evacuation pause to 745 // satisfy an allocation request of word_size. *succeeded will 746 // return whether the VM operation was successful (it did do an 747 // evacuation pause) or not (another thread beat us to it or the GC 748 // locker was active). Given that we should not be holding the 749 // Heap_lock when we enter this method, we will pass the 750 // gc_count_before (i.e., total_collections()) as a parameter since 751 // it has to be read while holding the Heap_lock. Currently, both 752 // methods that call do_collection_pause() release the Heap_lock 753 // before the call, so it's easy to read gc_count_before just before. 754 HeapWord* do_collection_pause(size_t word_size, 755 uint gc_count_before, 756 bool* succeeded, 757 GCCause::Cause gc_cause); 758 759 void wait_for_root_region_scanning(); 760 761 // The guts of the incremental collection pause, executed by the vm 762 // thread. It returns false if it is unable to do the collection due 763 // to the GC locker being active, true otherwise 764 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 765 766 // Actually do the work of evacuating the collection set. 767 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 768 769 void pre_evacuate_collection_set(); 770 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 771 772 // Print the header for the per-thread termination statistics. 773 static void print_termination_stats_hdr(); 774 // Print actual per-thread termination statistics. 775 void print_termination_stats(uint worker_id, 776 double elapsed_ms, 777 double strong_roots_ms, 778 double term_ms, 779 size_t term_attempts, 780 size_t alloc_buffer_waste, 781 size_t undo_waste) const; 782 // Update object copying statistics. 783 void record_obj_copy_mem_stats(); 784 785 // The hot card cache for remembered set insertion optimization. 786 G1HotCardCache* _hot_card_cache; 787 788 // The g1 remembered set of the heap. 789 G1RemSet* _g1_rem_set; 790 791 // A set of cards that cover the objects for which the Rsets should be updated 792 // concurrently after the collection. 793 DirtyCardQueueSet _dirty_card_queue_set; 794 795 // After a collection pause, convert the regions in the collection set into free 796 // regions. 797 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 798 799 // Abandon the current collection set without recording policy 800 // statistics or updating free lists. 801 void abandon_collection_set(G1CollectionSet* collection_set); 802 803 // The concurrent marker (and the thread it runs in.) 804 G1ConcurrentMark* _cm; 805 ConcurrentMarkThread* _cmThread; 806 807 // The concurrent refiner. 808 ConcurrentG1Refine* _cg1r; 809 810 // The parallel task queues 811 RefToScanQueueSet *_task_queues; 812 813 // True iff a evacuation has failed in the current collection. 814 bool _evacuation_failed; 815 816 EvacuationFailedInfo* _evacuation_failed_info_array; 817 818 // Failed evacuations cause some logical from-space objects to have 819 // forwarding pointers to themselves. Reset them. 820 void remove_self_forwarding_pointers(); 821 822 // Restore the objects in the regions in the collection set after an 823 // evacuation failure. 824 void restore_after_evac_failure(); 825 826 PreservedMarksSet _preserved_marks_set; 827 828 // Preserve the mark of "obj", if necessary, in preparation for its mark 829 // word being overwritten with a self-forwarding-pointer. 830 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 831 832 #ifndef PRODUCT 833 // Support for forcing evacuation failures. Analogous to 834 // PromotionFailureALot for the other collectors. 835 836 // Records whether G1EvacuationFailureALot should be in effect 837 // for the current GC 838 bool _evacuation_failure_alot_for_current_gc; 839 840 // Used to record the GC number for interval checking when 841 // determining whether G1EvaucationFailureALot is in effect 842 // for the current GC. 843 size_t _evacuation_failure_alot_gc_number; 844 845 // Count of the number of evacuations between failures. 846 volatile size_t _evacuation_failure_alot_count; 847 848 // Set whether G1EvacuationFailureALot should be in effect 849 // for the current GC (based upon the type of GC and which 850 // command line flags are set); 851 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 852 bool during_initial_mark, 853 bool during_marking); 854 855 inline void set_evacuation_failure_alot_for_current_gc(); 856 857 // Return true if it's time to cause an evacuation failure. 858 inline bool evacuation_should_fail(); 859 860 // Reset the G1EvacuationFailureALot counters. Should be called at 861 // the end of an evacuation pause in which an evacuation failure occurred. 862 inline void reset_evacuation_should_fail(); 863 #endif // !PRODUCT 864 865 // ("Weak") Reference processing support. 866 // 867 // G1 has 2 instances of the reference processor class. One 868 // (_ref_processor_cm) handles reference object discovery 869 // and subsequent processing during concurrent marking cycles. 870 // 871 // The other (_ref_processor_stw) handles reference object 872 // discovery and processing during full GCs and incremental 873 // evacuation pauses. 874 // 875 // During an incremental pause, reference discovery will be 876 // temporarily disabled for _ref_processor_cm and will be 877 // enabled for _ref_processor_stw. At the end of the evacuation 878 // pause references discovered by _ref_processor_stw will be 879 // processed and discovery will be disabled. The previous 880 // setting for reference object discovery for _ref_processor_cm 881 // will be re-instated. 882 // 883 // At the start of marking: 884 // * Discovery by the CM ref processor is verified to be inactive 885 // and it's discovered lists are empty. 886 // * Discovery by the CM ref processor is then enabled. 887 // 888 // At the end of marking: 889 // * Any references on the CM ref processor's discovered 890 // lists are processed (possibly MT). 891 // 892 // At the start of full GC we: 893 // * Disable discovery by the CM ref processor and 894 // empty CM ref processor's discovered lists 895 // (without processing any entries). 896 // * Verify that the STW ref processor is inactive and it's 897 // discovered lists are empty. 898 // * Temporarily set STW ref processor discovery as single threaded. 899 // * Temporarily clear the STW ref processor's _is_alive_non_header 900 // field. 901 // * Finally enable discovery by the STW ref processor. 902 // 903 // The STW ref processor is used to record any discovered 904 // references during the full GC. 905 // 906 // At the end of a full GC we: 907 // * Enqueue any reference objects discovered by the STW ref processor 908 // that have non-live referents. This has the side-effect of 909 // making the STW ref processor inactive by disabling discovery. 910 // * Verify that the CM ref processor is still inactive 911 // and no references have been placed on it's discovered 912 // lists (also checked as a precondition during initial marking). 913 914 // The (stw) reference processor... 915 ReferenceProcessor* _ref_processor_stw; 916 917 STWGCTimer* _gc_timer_stw; 918 919 G1NewTracer* _gc_tracer_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 HeapRegionClaimerBase* 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 // Returns the HeapRegion that contains addr. addr must not be NULL. 1225 template <class T> 1226 inline HeapRegion* heap_region_containing(const T addr) const; 1227 1228 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1229 // each address in the (reserved) heap is a member of exactly 1230 // one block. The defining characteristic of a block is that it is 1231 // possible to find its size, and thus to progress forward to the next 1232 // block. (Blocks may be of different sizes.) Thus, blocks may 1233 // represent Java objects, or they might be free blocks in a 1234 // free-list-based heap (or subheap), as long as the two kinds are 1235 // distinguishable and the size of each is determinable. 1236 1237 // Returns the address of the start of the "block" that contains the 1238 // address "addr". We say "blocks" instead of "object" since some heaps 1239 // may not pack objects densely; a chunk may either be an object or a 1240 // non-object. 1241 virtual HeapWord* block_start(const void* addr) const; 1242 1243 // Requires "addr" to be the start of a chunk, and returns its size. 1244 // "addr + size" is required to be the start of a new chunk, or the end 1245 // of the active area of the heap. 1246 virtual size_t block_size(const HeapWord* addr) const; 1247 1248 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1249 // the block is an object. 1250 virtual bool block_is_obj(const HeapWord* addr) const; 1251 1252 // Section on thread-local allocation buffers (TLABs) 1253 // See CollectedHeap for semantics. 1254 1255 bool supports_tlab_allocation() const; 1256 size_t tlab_capacity(Thread* ignored) const; 1257 size_t tlab_used(Thread* ignored) const; 1258 size_t max_tlab_size() const; 1259 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1260 1261 // Can a compiler initialize a new object without store barriers? 1262 // This permission only extends from the creation of a new object 1263 // via a TLAB up to the first subsequent safepoint. If such permission 1264 // is granted for this heap type, the compiler promises to call 1265 // defer_store_barrier() below on any slow path allocation of 1266 // a new object for which such initializing store barriers will 1267 // have been elided. G1, like CMS, allows this, but should be 1268 // ready to provide a compensating write barrier as necessary 1269 // if that storage came out of a non-young region. The efficiency 1270 // of this implementation depends crucially on being able to 1271 // answer very efficiently in constant time whether a piece of 1272 // storage in the heap comes from a young region or not. 1273 // See ReduceInitialCardMarks. 1274 virtual bool can_elide_tlab_store_barriers() const { 1275 return true; 1276 } 1277 1278 virtual bool card_mark_must_follow_store() const { 1279 return true; 1280 } 1281 1282 inline bool is_in_young(const oop obj); 1283 1284 virtual bool is_scavengable(const void* addr); 1285 1286 // We don't need barriers for initializing stores to objects 1287 // in the young gen: for the SATB pre-barrier, there is no 1288 // pre-value that needs to be remembered; for the remembered-set 1289 // update logging post-barrier, we don't maintain remembered set 1290 // information for young gen objects. 1291 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1292 1293 // Returns "true" iff the given word_size is "very large". 1294 static bool is_humongous(size_t word_size) { 1295 // Note this has to be strictly greater-than as the TLABs 1296 // are capped at the humongous threshold and we want to 1297 // ensure that we don't try to allocate a TLAB as 1298 // humongous and that we don't allocate a humongous 1299 // object in a TLAB. 1300 return word_size > _humongous_object_threshold_in_words; 1301 } 1302 1303 // Returns the humongous threshold for a specific region size 1304 static size_t humongous_threshold_for(size_t region_size) { 1305 return (region_size / 2); 1306 } 1307 1308 // Returns the number of regions the humongous object of the given word size 1309 // requires. 1310 static size_t humongous_obj_size_in_regions(size_t word_size); 1311 1312 // Print the maximum heap capacity. 1313 virtual size_t max_capacity() const; 1314 1315 virtual jlong millis_since_last_gc(); 1316 1317 1318 // Convenience function to be used in situations where the heap type can be 1319 // asserted to be this type. 1320 static G1CollectedHeap* heap(); 1321 1322 void set_region_short_lived_locked(HeapRegion* hr); 1323 // add appropriate methods for any other surv rate groups 1324 1325 const G1SurvivorRegions* survivor() const { return &_survivor; } 1326 1327 uint survivor_regions_count() const { 1328 return _survivor.length(); 1329 } 1330 1331 uint eden_regions_count() const { 1332 return _eden.length(); 1333 } 1334 1335 uint young_regions_count() const { 1336 return _eden.length() + _survivor.length(); 1337 } 1338 1339 uint old_regions_count() const { return _old_set.length(); } 1340 1341 uint humongous_regions_count() const { return _humongous_set.length(); } 1342 1343 #ifdef ASSERT 1344 bool check_young_list_empty(); 1345 #endif 1346 1347 // *** Stuff related to concurrent marking. It's not clear to me that so 1348 // many of these need to be public. 1349 1350 // The functions below are helper functions that a subclass of 1351 // "CollectedHeap" can use in the implementation of its virtual 1352 // functions. 1353 // This performs a concurrent marking of the live objects in a 1354 // bitmap off to the side. 1355 void doConcurrentMark(); 1356 1357 bool isMarkedNext(oop obj) const; 1358 1359 // Determine if an object is dead, given the object and also 1360 // the region to which the object belongs. An object is dead 1361 // iff a) it was not allocated since the last mark, b) it 1362 // is not marked, and c) it is not in an archive region. 1363 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1364 return 1365 hr->is_obj_dead(obj, _cm->prevMarkBitMap()) && 1366 !hr->is_archive(); 1367 } 1368 1369 // This function returns true when an object has been 1370 // around since the previous marking and hasn't yet 1371 // been marked during this marking, and is not in an archive region. 1372 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1373 return 1374 !hr->obj_allocated_since_next_marking(obj) && 1375 !isMarkedNext(obj) && 1376 !hr->is_archive(); 1377 } 1378 1379 // Determine if an object is dead, given only the object itself. 1380 // This will find the region to which the object belongs and 1381 // then call the region version of the same function. 1382 1383 // Added if it is NULL it isn't dead. 1384 1385 inline bool is_obj_dead(const oop obj) const; 1386 1387 inline bool is_obj_ill(const oop obj) const; 1388 1389 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1390 1391 // Refinement 1392 1393 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1394 1395 // Optimized nmethod scanning support routines 1396 1397 // Register the given nmethod with the G1 heap. 1398 virtual void register_nmethod(nmethod* nm); 1399 1400 // Unregister the given nmethod from the G1 heap. 1401 virtual void unregister_nmethod(nmethod* nm); 1402 1403 // Free up superfluous code root memory. 1404 void purge_code_root_memory(); 1405 1406 // Rebuild the strong code root lists for each region 1407 // after a full GC. 1408 void rebuild_strong_code_roots(); 1409 1410 // Partial cleaning used when class unloading is disabled. 1411 // Let the caller choose what structures to clean out: 1412 // - StringTable 1413 // - SymbolTable 1414 // - StringDeduplication structures 1415 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1416 1417 // Complete cleaning used when class unloading is enabled. 1418 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1419 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1420 1421 // Redirty logged cards in the refinement queue. 1422 void redirty_logged_cards(); 1423 // Verification 1424 1425 // Perform any cleanup actions necessary before allowing a verification. 1426 virtual void prepare_for_verify(); 1427 1428 // Perform verification. 1429 1430 // vo == UsePrevMarking -> use "prev" marking information, 1431 // vo == UseNextMarking -> use "next" marking information 1432 // vo == UseMarkWord -> use the mark word in the object header 1433 // 1434 // NOTE: Only the "prev" marking information is guaranteed to be 1435 // consistent most of the time, so most calls to this should use 1436 // vo == UsePrevMarking. 1437 // Currently, there is only one case where this is called with 1438 // vo == UseNextMarking, which is to verify the "next" marking 1439 // information at the end of remark. 1440 // Currently there is only one place where this is called with 1441 // vo == UseMarkWord, which is to verify the marking during a 1442 // full GC. 1443 void verify(VerifyOption vo); 1444 1445 // WhiteBox testing support. 1446 virtual bool supports_concurrent_phase_control() const; 1447 virtual const char* const* concurrent_phases() const; 1448 virtual bool request_concurrent_phase(const char* phase); 1449 1450 // The methods below are here for convenience and dispatch the 1451 // appropriate method depending on value of the given VerifyOption 1452 // parameter. The values for that parameter, and their meanings, 1453 // are the same as those above. 1454 1455 bool is_obj_dead_cond(const oop obj, 1456 const HeapRegion* hr, 1457 const VerifyOption vo) const; 1458 1459 bool is_obj_dead_cond(const oop obj, 1460 const VerifyOption vo) const; 1461 1462 G1HeapSummary create_g1_heap_summary(); 1463 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1464 1465 // Printing 1466 private: 1467 void print_heap_regions() const; 1468 void print_regions_on(outputStream* st) const; 1469 1470 public: 1471 virtual void print_on(outputStream* st) const; 1472 virtual void print_extended_on(outputStream* st) const; 1473 virtual void print_on_error(outputStream* st) const; 1474 1475 virtual void print_gc_threads_on(outputStream* st) const; 1476 virtual void gc_threads_do(ThreadClosure* tc) const; 1477 1478 // Override 1479 void print_tracing_info() const; 1480 1481 // The following two methods are helpful for debugging RSet issues. 1482 void print_cset_rsets() PRODUCT_RETURN; 1483 void print_all_rsets() PRODUCT_RETURN; 1484 1485 public: 1486 size_t pending_card_num(); 1487 1488 protected: 1489 size_t _max_heap_capacity; 1490 }; 1491 1492 class G1ParEvacuateFollowersClosure : public VoidClosure { 1493 private: 1494 double _start_term; 1495 double _term_time; 1496 size_t _term_attempts; 1497 1498 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1499 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1500 protected: 1501 G1CollectedHeap* _g1h; 1502 G1ParScanThreadState* _par_scan_state; 1503 RefToScanQueueSet* _queues; 1504 ParallelTaskTerminator* _terminator; 1505 1506 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1507 RefToScanQueueSet* queues() { return _queues; } 1508 ParallelTaskTerminator* terminator() { return _terminator; } 1509 1510 public: 1511 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1512 G1ParScanThreadState* par_scan_state, 1513 RefToScanQueueSet* queues, 1514 ParallelTaskTerminator* terminator) 1515 : _g1h(g1h), _par_scan_state(par_scan_state), 1516 _queues(queues), _terminator(terminator), 1517 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1518 1519 void do_void(); 1520 1521 double term_time() const { return _term_time; } 1522 size_t term_attempts() const { return _term_attempts; } 1523 1524 private: 1525 inline bool offer_termination(); 1526 }; 1527 1528 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP