1 /* 2 * Copyright (c) 2001, 2016, 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/g1HRPrinter.hpp" 35 #include "gc/g1/g1InCSetState.hpp" 36 #include "gc/g1/g1MonitoringSupport.hpp" 37 #include "gc/g1/g1EvacFailure.hpp" 38 #include "gc/g1/g1EvacStats.hpp" 39 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 40 #include "gc/g1/g1YCTypes.hpp" 41 #include "gc/g1/hSpaceCounters.hpp" 42 #include "gc/g1/heapRegionManager.hpp" 43 #include "gc/g1/heapRegionSet.hpp" 44 #include "gc/g1/youngList.hpp" 45 #include "gc/shared/barrierSet.hpp" 46 #include "gc/shared/collectedHeap.hpp" 47 #include "gc/shared/plab.hpp" 48 #include "memory/memRegion.hpp" 49 #include "utilities/stack.hpp" 50 51 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 52 // It uses the "Garbage First" heap organization and algorithm, which 53 // may combine concurrent marking with parallel, incremental compaction of 54 // heap subsets that will yield large amounts of garbage. 55 56 // Forward declarations 57 class HeapRegion; 58 class HRRSCleanupTask; 59 class GenerationSpec; 60 class OopsInHeapRegionClosure; 61 class G1ParScanThreadState; 62 class G1ParScanThreadStateSet; 63 class G1KlassScanClosure; 64 class G1ParScanThreadState; 65 class ObjectClosure; 66 class SpaceClosure; 67 class CompactibleSpaceClosure; 68 class Space; 69 class G1CollectionSet; 70 class G1CollectorPolicy; 71 class G1RemSet; 72 class HeapRegionRemSetIterator; 73 class G1ConcurrentMark; 74 class ConcurrentMarkThread; 75 class ConcurrentG1Refine; 76 class GenerationCounters; 77 class STWGCTimer; 78 class G1NewTracer; 79 class EvacuationFailedInfo; 80 class nmethod; 81 class Ticks; 82 class WorkGang; 83 class G1Allocator; 84 class G1ArchiveAllocator; 85 class G1HeapVerifier; 86 class G1HeapSizingPolicy; 87 88 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 89 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 90 91 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 92 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 93 94 // The G1 STW is alive closure. 95 // An instance is embedded into the G1CH and used as the 96 // (optional) _is_alive_non_header closure in the STW 97 // reference processor. It is also extensively used during 98 // reference processing during STW evacuation pauses. 99 class G1STWIsAliveClosure: public BoolObjectClosure { 100 G1CollectedHeap* _g1; 101 public: 102 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 103 bool do_object_b(oop p); 104 }; 105 106 class RefineCardTableEntryClosure; 107 108 class G1RegionMappingChangedListener : public G1MappingChangedListener { 109 private: 110 void reset_from_card_cache(uint start_idx, size_t num_regions); 111 public: 112 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 113 }; 114 115 class G1CollectedHeap : public CollectedHeap { 116 friend class VM_CollectForMetadataAllocation; 117 friend class VM_G1CollectForAllocation; 118 friend class VM_G1CollectFull; 119 friend class VM_G1IncCollectionPause; 120 friend class VMStructs; 121 friend class MutatorAllocRegion; 122 friend class G1GCAllocRegion; 123 friend class G1HeapVerifier; 124 125 // Closures used in implementation. 126 friend class G1ParScanThreadState; 127 friend class G1ParScanThreadStateSet; 128 friend class G1ParTask; 129 friend class G1PLABAllocator; 130 friend class G1PrepareCompactClosure; 131 132 // Other related classes. 133 friend class HeapRegionClaimer; 134 135 // Testing classes. 136 friend class G1CheckCSetFastTableClosure; 137 138 private: 139 WorkGang* _workers; 140 141 static size_t _humongous_object_threshold_in_words; 142 143 // The secondary free list which contains regions that have been 144 // freed up during the cleanup process. This will be appended to 145 // the master free list when appropriate. 146 FreeRegionList _secondary_free_list; 147 148 // It keeps track of the old regions. 149 HeapRegionSet _old_set; 150 151 // It keeps track of the humongous regions. 152 HeapRegionSet _humongous_set; 153 154 void eagerly_reclaim_humongous_regions(); 155 156 // The number of regions we could create by expansion. 157 uint _expansion_regions; 158 159 // The block offset table for the G1 heap. 160 G1BlockOffsetTable* _bot; 161 162 // Tears down the region sets / lists so that they are empty and the 163 // regions on the heap do not belong to a region set / list. The 164 // only exception is the humongous set which we leave unaltered. If 165 // free_list_only is true, it will only tear down the master free 166 // list. It is called before a Full GC (free_list_only == false) or 167 // before heap shrinking (free_list_only == true). 168 void tear_down_region_sets(bool free_list_only); 169 170 // Rebuilds the region sets / lists so that they are repopulated to 171 // reflect the contents of the heap. The only exception is the 172 // humongous set which was not torn down in the first place. If 173 // free_list_only is true, it will only rebuild the master free 174 // list. It is called after a Full GC (free_list_only == false) or 175 // after heap shrinking (free_list_only == true). 176 void rebuild_region_sets(bool free_list_only); 177 178 // Callback for region mapping changed events. 179 G1RegionMappingChangedListener _listener; 180 181 // The sequence of all heap regions in the heap. 182 HeapRegionManager _hrm; 183 184 // Manages all allocations with regions except humongous object allocations. 185 G1Allocator* _allocator; 186 187 // Manages all heap verification. 188 G1HeapVerifier* _verifier; 189 190 // Outside of GC pauses, the number of bytes used in all regions other 191 // than the current allocation region(s). 192 size_t _summary_bytes_used; 193 194 void increase_used(size_t bytes); 195 void decrease_used(size_t bytes); 196 197 void set_used(size_t bytes); 198 199 // Class that handles archive allocation ranges. 200 G1ArchiveAllocator* _archive_allocator; 201 202 // Statistics for each allocation context 203 AllocationContextStats _allocation_context_stats; 204 205 // GC allocation statistics policy for survivors. 206 G1EvacStats _survivor_evac_stats; 207 208 // GC allocation statistics policy for tenured objects. 209 G1EvacStats _old_evac_stats; 210 211 // It specifies whether we should attempt to expand the heap after a 212 // region allocation failure. If heap expansion fails we set this to 213 // false so that we don't re-attempt the heap expansion (it's likely 214 // that subsequent expansion attempts will also fail if one fails). 215 // Currently, it is only consulted during GC and it's reset at the 216 // start of each GC. 217 bool _expand_heap_after_alloc_failure; 218 219 // Helper for monitoring and management support. 220 G1MonitoringSupport* _g1mm; 221 222 // Records whether the region at the given index is (still) a 223 // candidate for eager reclaim. Only valid for humongous start 224 // regions; other regions have unspecified values. Humongous start 225 // regions are initialized at start of collection pause, with 226 // candidates removed from the set as they are found reachable from 227 // roots or the young generation. 228 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 229 protected: 230 bool default_value() const { return false; } 231 public: 232 void clear() { G1BiasedMappedArray<bool>::clear(); } 233 void set_candidate(uint region, bool value) { 234 set_by_index(region, value); 235 } 236 bool is_candidate(uint region) { 237 return get_by_index(region); 238 } 239 }; 240 241 HumongousReclaimCandidates _humongous_reclaim_candidates; 242 // Stores whether during humongous object registration we found candidate regions. 243 // If not, we can skip a few steps. 244 bool _has_humongous_reclaim_candidates; 245 246 volatile unsigned _gc_time_stamp; 247 248 G1HRPrinter _hr_printer; 249 250 // It decides whether an explicit GC should start a concurrent cycle 251 // instead of doing a STW GC. Currently, a concurrent cycle is 252 // explicitly started if: 253 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 254 // (b) cause == _g1_humongous_allocation 255 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 256 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 257 // (e) cause == _update_allocation_context_stats_inc 258 // (f) cause == _wb_conc_mark 259 bool should_do_concurrent_full_gc(GCCause::Cause cause); 260 261 // indicates whether we are in young or mixed GC mode 262 G1CollectorState _collector_state; 263 264 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 265 // concurrent cycles) we have started. 266 volatile uint _old_marking_cycles_started; 267 268 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 269 // concurrent cycles) we have completed. 270 volatile uint _old_marking_cycles_completed; 271 272 // This is a non-product method that is helpful for testing. It is 273 // called at the end of a GC and artificially expands the heap by 274 // allocating a number of dead regions. This way we can induce very 275 // frequent marking cycles and stress the cleanup / concurrent 276 // cleanup code more (as all the regions that will be allocated by 277 // this method will be found dead by the marking cycle). 278 void allocate_dummy_regions() PRODUCT_RETURN; 279 280 // Clear RSets after a compaction. It also resets the GC time stamps. 281 void clear_rsets_post_compaction(); 282 283 // If the HR printer is active, dump the state of the regions in the 284 // heap after a compaction. 285 void print_hrm_post_compaction(); 286 287 // Create a memory mapper for auxiliary data structures of the given size and 288 // translation factor. 289 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 290 size_t size, 291 size_t translation_factor); 292 293 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 294 295 void process_weak_jni_handles(); 296 297 // These are macros so that, if the assert fires, we get the correct 298 // line number, file, etc. 299 300 #define heap_locking_asserts_params(_extra_message_) \ 301 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 302 (_extra_message_), \ 303 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 304 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 305 BOOL_TO_STR(Thread::current()->is_VM_thread()) 306 307 #define assert_heap_locked() \ 308 do { \ 309 assert(Heap_lock->owned_by_self(), \ 310 heap_locking_asserts_params("should be holding the Heap_lock")); \ 311 } while (0) 312 313 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 314 do { \ 315 assert(Heap_lock->owned_by_self() || \ 316 (SafepointSynchronize::is_at_safepoint() && \ 317 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 318 heap_locking_asserts_params("should be holding the Heap_lock or " \ 319 "should be at a safepoint")); \ 320 } while (0) 321 322 #define assert_heap_locked_and_not_at_safepoint() \ 323 do { \ 324 assert(Heap_lock->owned_by_self() && \ 325 !SafepointSynchronize::is_at_safepoint(), \ 326 heap_locking_asserts_params("should be holding the Heap_lock and " \ 327 "should not be at a safepoint")); \ 328 } while (0) 329 330 #define assert_heap_not_locked() \ 331 do { \ 332 assert(!Heap_lock->owned_by_self(), \ 333 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 334 } while (0) 335 336 #define assert_heap_not_locked_and_not_at_safepoint() \ 337 do { \ 338 assert(!Heap_lock->owned_by_self() && \ 339 !SafepointSynchronize::is_at_safepoint(), \ 340 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 341 "should not be at a safepoint")); \ 342 } while (0) 343 344 #define assert_at_safepoint(_should_be_vm_thread_) \ 345 do { \ 346 assert(SafepointSynchronize::is_at_safepoint() && \ 347 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 348 heap_locking_asserts_params("should be at a safepoint")); \ 349 } while (0) 350 351 #define assert_not_at_safepoint() \ 352 do { \ 353 assert(!SafepointSynchronize::is_at_safepoint(), \ 354 heap_locking_asserts_params("should not be at a safepoint")); \ 355 } while (0) 356 357 protected: 358 359 // The young region list. 360 YoungList* _young_list; 361 362 // The current policy object for the collector. 363 G1CollectorPolicy* _g1_policy; 364 G1HeapSizingPolicy* _heap_sizing_policy; 365 366 G1CollectionSet _collection_set; 367 368 // This is the second level of trying to allocate a new region. If 369 // new_region() didn't find a region on the free_list, this call will 370 // check whether there's anything available on the 371 // secondary_free_list and/or wait for more regions to appear on 372 // that list, if _free_regions_coming is set. 373 HeapRegion* new_region_try_secondary_free_list(bool is_old); 374 375 // Try to allocate a single non-humongous HeapRegion sufficient for 376 // an allocation of the given word_size. If do_expand is true, 377 // attempt to expand the heap if necessary to satisfy the allocation 378 // request. If the region is to be used as an old region or for a 379 // humongous object, set is_old to true. If not, to false. 380 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 381 382 // Initialize a contiguous set of free regions of length num_regions 383 // and starting at index first so that they appear as a single 384 // humongous region. 385 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 386 uint num_regions, 387 size_t word_size, 388 AllocationContext_t context); 389 390 // Attempt to allocate a humongous object of the given size. Return 391 // NULL if unsuccessful. 392 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 393 394 // The following two methods, allocate_new_tlab() and 395 // mem_allocate(), are the two main entry points from the runtime 396 // into the G1's allocation routines. They have the following 397 // assumptions: 398 // 399 // * They should both be called outside safepoints. 400 // 401 // * They should both be called without holding the Heap_lock. 402 // 403 // * All allocation requests for new TLABs should go to 404 // allocate_new_tlab(). 405 // 406 // * All non-TLAB allocation requests should go to mem_allocate(). 407 // 408 // * If either call cannot satisfy the allocation request using the 409 // current allocating region, they will try to get a new one. If 410 // this fails, they will attempt to do an evacuation pause and 411 // retry the allocation. 412 // 413 // * If all allocation attempts fail, even after trying to schedule 414 // an evacuation pause, allocate_new_tlab() will return NULL, 415 // whereas mem_allocate() will attempt a heap expansion and/or 416 // schedule a Full GC. 417 // 418 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 419 // should never be called with word_size being humongous. All 420 // humongous allocation requests should go to mem_allocate() which 421 // will satisfy them with a special path. 422 423 virtual HeapWord* allocate_new_tlab(size_t word_size); 424 425 virtual HeapWord* mem_allocate(size_t word_size, 426 bool* gc_overhead_limit_was_exceeded); 427 428 // The following three methods take a gc_count_before_ret 429 // parameter which is used to return the GC count if the method 430 // returns NULL. Given that we are required to read the GC count 431 // while holding the Heap_lock, and these paths will take the 432 // Heap_lock at some point, it's easier to get them to read the GC 433 // count while holding the Heap_lock before they return NULL instead 434 // of the caller (namely: mem_allocate()) having to also take the 435 // Heap_lock just to read the GC count. 436 437 // First-level mutator allocation attempt: try to allocate out of 438 // the mutator alloc region without taking the Heap_lock. This 439 // should only be used for non-humongous allocations. 440 inline HeapWord* attempt_allocation(size_t word_size, 441 uint* gc_count_before_ret, 442 uint* gclocker_retry_count_ret); 443 444 // Second-level mutator allocation attempt: take the Heap_lock and 445 // retry the allocation attempt, potentially scheduling a GC 446 // pause. This should only be used for non-humongous allocations. 447 HeapWord* attempt_allocation_slow(size_t word_size, 448 AllocationContext_t context, 449 uint* gc_count_before_ret, 450 uint* gclocker_retry_count_ret); 451 452 // Takes the Heap_lock and attempts a humongous allocation. It can 453 // potentially schedule a GC pause. 454 HeapWord* attempt_allocation_humongous(size_t word_size, 455 uint* gc_count_before_ret, 456 uint* gclocker_retry_count_ret); 457 458 // Allocation attempt that should be called during safepoints (e.g., 459 // at the end of a successful GC). expect_null_mutator_alloc_region 460 // specifies whether the mutator alloc region is expected to be NULL 461 // or not. 462 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 463 AllocationContext_t context, 464 bool expect_null_mutator_alloc_region); 465 466 // These methods are the "callbacks" from the G1AllocRegion class. 467 468 // For mutator alloc regions. 469 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 470 void retire_mutator_alloc_region(HeapRegion* alloc_region, 471 size_t allocated_bytes); 472 473 // For GC alloc regions. 474 bool has_more_regions(InCSetState dest); 475 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 476 void retire_gc_alloc_region(HeapRegion* alloc_region, 477 size_t allocated_bytes, InCSetState dest); 478 479 // - if explicit_gc is true, the GC is for a System.gc() etc, 480 // otherwise it's for a failed allocation. 481 // - if clear_all_soft_refs is true, all soft references should be 482 // cleared during the GC. 483 // - it returns false if it is unable to do the collection due to the 484 // GC locker being active, true otherwise. 485 bool do_full_collection(bool explicit_gc, 486 bool clear_all_soft_refs); 487 488 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 489 virtual void do_full_collection(bool clear_all_soft_refs); 490 491 // Resize the heap if necessary after a full collection. 492 void resize_if_necessary_after_full_collection(); 493 494 // Callback from VM_G1CollectForAllocation operation. 495 // This function does everything necessary/possible to satisfy a 496 // failed allocation request (including collection, expansion, etc.) 497 HeapWord* satisfy_failed_allocation(size_t word_size, 498 AllocationContext_t context, 499 bool* succeeded); 500 private: 501 // Helper method for satisfy_failed_allocation() 502 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 503 AllocationContext_t context, 504 bool do_gc, 505 bool clear_all_soft_refs, 506 bool expect_null_mutator_alloc_region, 507 bool* gc_succeeded); 508 509 protected: 510 // Attempting to expand the heap sufficiently 511 // to support an allocation of the given "word_size". If 512 // successful, perform the allocation and return the address of the 513 // allocated block, or else "NULL". 514 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 515 516 // Preserve any referents discovered by concurrent marking that have not yet been 517 // copied by the STW pause. 518 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 519 // Process any reference objects discovered during 520 // an incremental evacuation pause. 521 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 522 523 // Enqueue any remaining discovered references 524 // after processing. 525 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 526 527 // Merges the information gathered on a per-thread basis for all worker threads 528 // during GC into global variables. 529 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 530 public: 531 WorkGang* workers() const { return _workers; } 532 533 G1Allocator* allocator() { 534 return _allocator; 535 } 536 537 G1HeapVerifier* verifier() { 538 return _verifier; 539 } 540 541 G1MonitoringSupport* g1mm() { 542 assert(_g1mm != NULL, "should have been initialized"); 543 return _g1mm; 544 } 545 546 // Expand the garbage-first heap by at least the given size (in bytes!). 547 // Returns true if the heap was expanded by the requested amount; 548 // false otherwise. 549 // (Rounds up to a HeapRegion boundary.) 550 bool expand(size_t expand_bytes, double* expand_time_ms = NULL); 551 552 // Returns the PLAB statistics for a given destination. 553 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 554 555 // Determines PLAB size for a given destination. 556 inline size_t desired_plab_sz(InCSetState dest); 557 558 inline AllocationContextStats& allocation_context_stats(); 559 560 // Do anything common to GC's. 561 void gc_prologue(bool full); 562 void gc_epilogue(bool full); 563 564 // Modify the reclaim candidate set and test for presence. 565 // These are only valid for starts_humongous regions. 566 inline void set_humongous_reclaim_candidate(uint region, bool value); 567 inline bool is_humongous_reclaim_candidate(uint region); 568 569 // Remove from the reclaim candidate set. Also remove from the 570 // collection set so that later encounters avoid the slow path. 571 inline void set_humongous_is_live(oop obj); 572 573 // Register the given region to be part of the collection set. 574 inline void register_humongous_region_with_cset(uint index); 575 // Register regions with humongous objects (actually on the start region) in 576 // the in_cset_fast_test table. 577 void register_humongous_regions_with_cset(); 578 // We register a region with the fast "in collection set" test. We 579 // simply set to true the array slot corresponding to this region. 580 void register_young_region_with_cset(HeapRegion* r) { 581 _in_cset_fast_test.set_in_young(r->hrm_index()); 582 } 583 void register_old_region_with_cset(HeapRegion* r) { 584 _in_cset_fast_test.set_in_old(r->hrm_index()); 585 } 586 inline void register_ext_region_with_cset(HeapRegion* r) { 587 _in_cset_fast_test.set_ext(r->hrm_index()); 588 } 589 void clear_in_cset(const HeapRegion* hr) { 590 _in_cset_fast_test.clear(hr); 591 } 592 593 void clear_cset_fast_test() { 594 _in_cset_fast_test.clear(); 595 } 596 597 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 598 599 // This is called at the start of either a concurrent cycle or a Full 600 // GC to update the number of old marking cycles started. 601 void increment_old_marking_cycles_started(); 602 603 // This is called at the end of either a concurrent cycle or a Full 604 // GC to update the number of old marking cycles completed. Those two 605 // can happen in a nested fashion, i.e., we start a concurrent 606 // cycle, a Full GC happens half-way through it which ends first, 607 // and then the cycle notices that a Full GC happened and ends 608 // too. The concurrent parameter is a boolean to help us do a bit 609 // tighter consistency checking in the method. If concurrent is 610 // false, the caller is the inner caller in the nesting (i.e., the 611 // Full GC). If concurrent is true, the caller is the outer caller 612 // in this nesting (i.e., the concurrent cycle). Further nesting is 613 // not currently supported. The end of this call also notifies 614 // the FullGCCount_lock in case a Java thread is waiting for a full 615 // GC to happen (e.g., it called System.gc() with 616 // +ExplicitGCInvokesConcurrent). 617 void increment_old_marking_cycles_completed(bool concurrent); 618 619 uint old_marking_cycles_completed() { 620 return _old_marking_cycles_completed; 621 } 622 623 G1HRPrinter* hr_printer() { return &_hr_printer; } 624 625 // Allocates a new heap region instance. 626 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 627 628 // Allocate the highest free region in the reserved heap. This will commit 629 // regions as necessary. 630 HeapRegion* alloc_highest_free_region(); 631 632 // Frees a non-humongous region by initializing its contents and 633 // adding it to the free list that's passed as a parameter (this is 634 // usually a local list which will be appended to the master free 635 // list later). The used bytes of freed regions are accumulated in 636 // pre_used. If par is true, the region's RSet will not be freed 637 // up. The assumption is that this will be done later. 638 // The locked parameter indicates if the caller has already taken 639 // care of proper synchronization. This may allow some optimizations. 640 void free_region(HeapRegion* hr, 641 FreeRegionList* free_list, 642 bool par, 643 bool locked = false); 644 645 // It dirties the cards that cover the block so that the post 646 // write barrier never queues anything when updating objects on this 647 // block. It is assumed (and in fact we assert) that the block 648 // belongs to a young region. 649 inline void dirty_young_block(HeapWord* start, size_t word_size); 650 651 // Frees a humongous region by collapsing it into individual regions 652 // and calling free_region() for each of them. The freed regions 653 // will be added to the free list that's passed as a parameter (this 654 // is usually a local list which will be appended to the master free 655 // list later). The used bytes of freed regions are accumulated in 656 // pre_used. If par is true, the region's RSet will not be freed 657 // up. The assumption is that this will be done later. 658 void free_humongous_region(HeapRegion* hr, 659 FreeRegionList* free_list, 660 bool par); 661 662 // Facility for allocating in 'archive' regions in high heap memory and 663 // recording the allocated ranges. These should all be called from the 664 // VM thread at safepoints, without the heap lock held. They can be used 665 // to create and archive a set of heap regions which can be mapped at the 666 // same fixed addresses in a subsequent JVM invocation. 667 void begin_archive_alloc_range(); 668 669 // Check if the requested size would be too large for an archive allocation. 670 bool is_archive_alloc_too_large(size_t word_size); 671 672 // Allocate memory of the requested size from the archive region. This will 673 // return NULL if the size is too large or if no memory is available. It 674 // does not trigger a garbage collection. 675 HeapWord* archive_mem_allocate(size_t word_size); 676 677 // Optionally aligns the end address and returns the allocated ranges in 678 // an array of MemRegions in order of ascending addresses. 679 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 680 size_t end_alignment_in_bytes = 0); 681 682 // Facility for allocating a fixed range within the heap and marking 683 // the containing regions as 'archive'. For use at JVM init time, when the 684 // caller may mmap archived heap data at the specified range(s). 685 // Verify that the MemRegions specified in the argument array are within the 686 // reserved heap. 687 bool check_archive_addresses(MemRegion* range, size_t count); 688 689 // Commit the appropriate G1 regions containing the specified MemRegions 690 // and mark them as 'archive' regions. The regions in the array must be 691 // non-overlapping and in order of ascending address. 692 bool alloc_archive_regions(MemRegion* range, size_t count); 693 694 // Insert any required filler objects in the G1 regions around the specified 695 // ranges to make the regions parseable. This must be called after 696 // alloc_archive_regions, and after class loading has occurred. 697 void fill_archive_regions(MemRegion* range, size_t count); 698 699 // For each of the specified MemRegions, uncommit the containing G1 regions 700 // which had been allocated by alloc_archive_regions. This should be called 701 // rather than fill_archive_regions at JVM init time if the archive file 702 // mapping failed, with the same non-overlapping and sorted MemRegion array. 703 void dealloc_archive_regions(MemRegion* range, size_t count); 704 705 protected: 706 707 // Shrink the garbage-first heap by at most the given size (in bytes!). 708 // (Rounds down to a HeapRegion boundary.) 709 virtual void shrink(size_t expand_bytes); 710 void shrink_helper(size_t expand_bytes); 711 712 #if TASKQUEUE_STATS 713 static void print_taskqueue_stats_hdr(outputStream* const st); 714 void print_taskqueue_stats() const; 715 void reset_taskqueue_stats(); 716 #endif // TASKQUEUE_STATS 717 718 // Schedule the VM operation that will do an evacuation pause to 719 // satisfy an allocation request of word_size. *succeeded will 720 // return whether the VM operation was successful (it did do an 721 // evacuation pause) or not (another thread beat us to it or the GC 722 // locker was active). Given that we should not be holding the 723 // Heap_lock when we enter this method, we will pass the 724 // gc_count_before (i.e., total_collections()) as a parameter since 725 // it has to be read while holding the Heap_lock. Currently, both 726 // methods that call do_collection_pause() release the Heap_lock 727 // before the call, so it's easy to read gc_count_before just before. 728 HeapWord* do_collection_pause(size_t word_size, 729 uint gc_count_before, 730 bool* succeeded, 731 GCCause::Cause gc_cause); 732 733 void wait_for_root_region_scanning(); 734 735 // The guts of the incremental collection pause, executed by the vm 736 // thread. It returns false if it is unable to do the collection due 737 // to the GC locker being active, true otherwise 738 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 739 740 // Actually do the work of evacuating the collection set. 741 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 742 743 void pre_evacuate_collection_set(); 744 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 745 746 // Print the header for the per-thread termination statistics. 747 static void print_termination_stats_hdr(); 748 // Print actual per-thread termination statistics. 749 void print_termination_stats(uint worker_id, 750 double elapsed_ms, 751 double strong_roots_ms, 752 double term_ms, 753 size_t term_attempts, 754 size_t alloc_buffer_waste, 755 size_t undo_waste) const; 756 // Update object copying statistics. 757 void record_obj_copy_mem_stats(); 758 759 // The g1 remembered set of the heap. 760 G1RemSet* _g1_rem_set; 761 762 // A set of cards that cover the objects for which the Rsets should be updated 763 // concurrently after the collection. 764 DirtyCardQueueSet _dirty_card_queue_set; 765 766 // The closure used to refine a single card. 767 RefineCardTableEntryClosure* _refine_cte_cl; 768 769 // After a collection pause, make the regions in the CS into free 770 // regions. 771 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 772 773 // Abandon the current collection set without recording policy 774 // statistics or updating free lists. 775 void abandon_collection_set(HeapRegion* cs_head); 776 777 // The concurrent marker (and the thread it runs in.) 778 G1ConcurrentMark* _cm; 779 ConcurrentMarkThread* _cmThread; 780 781 // The concurrent refiner. 782 ConcurrentG1Refine* _cg1r; 783 784 // The parallel task queues 785 RefToScanQueueSet *_task_queues; 786 787 // True iff a evacuation has failed in the current collection. 788 bool _evacuation_failed; 789 790 EvacuationFailedInfo* _evacuation_failed_info_array; 791 792 // Failed evacuations cause some logical from-space objects to have 793 // forwarding pointers to themselves. Reset them. 794 void remove_self_forwarding_pointers(); 795 796 // Restore the preserved mark words for objects with self-forwarding pointers. 797 void restore_preserved_marks(); 798 799 // Restore the objects in the regions in the collection set after an 800 // evacuation failure. 801 void restore_after_evac_failure(); 802 803 // Stores marks with the corresponding oop that we need to preserve during evacuation 804 // failure. 805 OopAndMarkOopStack* _preserved_objs; 806 807 // Preserve the mark of "obj", if necessary, in preparation for its mark 808 // word being overwritten with a self-forwarding-pointer. 809 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 810 811 #ifndef PRODUCT 812 // Support for forcing evacuation failures. Analogous to 813 // PromotionFailureALot for the other collectors. 814 815 // Records whether G1EvacuationFailureALot should be in effect 816 // for the current GC 817 bool _evacuation_failure_alot_for_current_gc; 818 819 // Used to record the GC number for interval checking when 820 // determining whether G1EvaucationFailureALot is in effect 821 // for the current GC. 822 size_t _evacuation_failure_alot_gc_number; 823 824 // Count of the number of evacuations between failures. 825 volatile size_t _evacuation_failure_alot_count; 826 827 // Set whether G1EvacuationFailureALot should be in effect 828 // for the current GC (based upon the type of GC and which 829 // command line flags are set); 830 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 831 bool during_initial_mark, 832 bool during_marking); 833 834 inline void set_evacuation_failure_alot_for_current_gc(); 835 836 // Return true if it's time to cause an evacuation failure. 837 inline bool evacuation_should_fail(); 838 839 // Reset the G1EvacuationFailureALot counters. Should be called at 840 // the end of an evacuation pause in which an evacuation failure occurred. 841 inline void reset_evacuation_should_fail(); 842 #endif // !PRODUCT 843 844 // ("Weak") Reference processing support. 845 // 846 // G1 has 2 instances of the reference processor class. One 847 // (_ref_processor_cm) handles reference object discovery 848 // and subsequent processing during concurrent marking cycles. 849 // 850 // The other (_ref_processor_stw) handles reference object 851 // discovery and processing during full GCs and incremental 852 // evacuation pauses. 853 // 854 // During an incremental pause, reference discovery will be 855 // temporarily disabled for _ref_processor_cm and will be 856 // enabled for _ref_processor_stw. At the end of the evacuation 857 // pause references discovered by _ref_processor_stw will be 858 // processed and discovery will be disabled. The previous 859 // setting for reference object discovery for _ref_processor_cm 860 // will be re-instated. 861 // 862 // At the start of marking: 863 // * Discovery by the CM ref processor is verified to be inactive 864 // and it's discovered lists are empty. 865 // * Discovery by the CM ref processor is then enabled. 866 // 867 // At the end of marking: 868 // * Any references on the CM ref processor's discovered 869 // lists are processed (possibly MT). 870 // 871 // At the start of full GC we: 872 // * Disable discovery by the CM ref processor and 873 // empty CM ref processor's discovered lists 874 // (without processing any entries). 875 // * Verify that the STW ref processor is inactive and it's 876 // discovered lists are empty. 877 // * Temporarily set STW ref processor discovery as single threaded. 878 // * Temporarily clear the STW ref processor's _is_alive_non_header 879 // field. 880 // * Finally enable discovery by the STW ref processor. 881 // 882 // The STW ref processor is used to record any discovered 883 // references during the full GC. 884 // 885 // At the end of a full GC we: 886 // * Enqueue any reference objects discovered by the STW ref processor 887 // that have non-live referents. This has the side-effect of 888 // making the STW ref processor inactive by disabling discovery. 889 // * Verify that the CM ref processor is still inactive 890 // and no references have been placed on it's discovered 891 // lists (also checked as a precondition during initial marking). 892 893 // The (stw) reference processor... 894 ReferenceProcessor* _ref_processor_stw; 895 896 STWGCTimer* _gc_timer_stw; 897 898 G1NewTracer* _gc_tracer_stw; 899 900 // During reference object discovery, the _is_alive_non_header 901 // closure (if non-null) is applied to the referent object to 902 // determine whether the referent is live. If so then the 903 // reference object does not need to be 'discovered' and can 904 // be treated as a regular oop. This has the benefit of reducing 905 // the number of 'discovered' reference objects that need to 906 // be processed. 907 // 908 // Instance of the is_alive closure for embedding into the 909 // STW reference processor as the _is_alive_non_header field. 910 // Supplying a value for the _is_alive_non_header field is 911 // optional but doing so prevents unnecessary additions to 912 // the discovered lists during reference discovery. 913 G1STWIsAliveClosure _is_alive_closure_stw; 914 915 // The (concurrent marking) reference processor... 916 ReferenceProcessor* _ref_processor_cm; 917 918 // Instance of the concurrent mark is_alive closure for embedding 919 // into the Concurrent Marking reference processor as the 920 // _is_alive_non_header field. Supplying a value for the 921 // _is_alive_non_header field is optional but doing so prevents 922 // unnecessary additions to the discovered lists during reference 923 // discovery. 924 G1CMIsAliveClosure _is_alive_closure_cm; 925 926 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 927 HeapRegion** _worker_cset_start_region; 928 929 // Time stamp to validate the regions recorded in the cache 930 // used by G1CollectedHeap::start_cset_region_for_worker(). 931 // The heap region entry for a given worker is valid iff 932 // the associated time stamp value matches the current value 933 // of G1CollectedHeap::_gc_time_stamp. 934 uint* _worker_cset_start_region_time_stamp; 935 936 volatile bool _free_regions_coming; 937 938 public: 939 940 void set_refine_cte_cl_concurrency(bool concurrent); 941 942 RefToScanQueue *task_queue(uint i) const; 943 944 uint num_task_queues() const; 945 946 // A set of cards where updates happened during the GC 947 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 948 949 // Create a G1CollectedHeap with the specified policy. 950 // Must call the initialize method afterwards. 951 // May not return if something goes wrong. 952 G1CollectedHeap(G1CollectorPolicy* policy); 953 954 // Initialize the G1CollectedHeap to have the initial and 955 // maximum sizes and remembered and barrier sets 956 // specified by the policy object. 957 jint initialize(); 958 959 virtual void stop(); 960 961 // Return the (conservative) maximum heap alignment for any G1 heap 962 static size_t conservative_max_heap_alignment(); 963 964 // Does operations required after initialization has been done. 965 void post_initialize(); 966 967 // Initialize weak reference processing. 968 void ref_processing_init(); 969 970 virtual Name kind() const { 971 return CollectedHeap::G1CollectedHeap; 972 } 973 974 virtual const char* name() const { 975 return "G1"; 976 } 977 978 const G1CollectorState* collector_state() const { return &_collector_state; } 979 G1CollectorState* collector_state() { return &_collector_state; } 980 981 // The current policy object for the collector. 982 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 983 984 const G1CollectionSet* collection_set() const { return &_collection_set; } 985 G1CollectionSet* collection_set() { return &_collection_set; } 986 987 virtual CollectorPolicy* collector_policy() const; 988 989 // Adaptive size policy. No such thing for g1. 990 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 991 992 // The rem set and barrier set. 993 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 994 995 void scrub_rem_set(BitMap* region_bm, BitMap* card_bm); 996 997 unsigned get_gc_time_stamp() { 998 return _gc_time_stamp; 999 } 1000 1001 inline void reset_gc_time_stamp(); 1002 1003 void check_gc_time_stamps() PRODUCT_RETURN; 1004 1005 inline void increment_gc_time_stamp(); 1006 1007 // Reset the given region's GC timestamp. If it's starts humongous, 1008 // also reset the GC timestamp of its corresponding 1009 // continues humongous regions too. 1010 void reset_gc_time_stamps(HeapRegion* hr); 1011 1012 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1013 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1014 1015 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1016 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1017 1018 // The shared block offset table array. 1019 G1BlockOffsetTable* bot() const { return _bot; } 1020 1021 // Reference Processing accessors 1022 1023 // The STW reference processor.... 1024 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1025 1026 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1027 1028 // The Concurrent Marking reference processor... 1029 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1030 1031 virtual size_t capacity() const; 1032 virtual size_t used() const; 1033 // This should be called when we're not holding the heap lock. The 1034 // result might be a bit inaccurate. 1035 size_t used_unlocked() const; 1036 size_t recalculate_used() const; 1037 1038 // These virtual functions do the actual allocation. 1039 // Some heaps may offer a contiguous region for shared non-blocking 1040 // allocation, via inlined code (by exporting the address of the top and 1041 // end fields defining the extent of the contiguous allocation region.) 1042 // But G1CollectedHeap doesn't yet support this. 1043 1044 virtual bool is_maximal_no_gc() const { 1045 return _hrm.available() == 0; 1046 } 1047 1048 // The current number of regions in the heap. 1049 uint num_regions() const { return _hrm.length(); } 1050 1051 // The max number of regions in the heap. 1052 uint max_regions() const { return _hrm.max_length(); } 1053 1054 // The number of regions that are completely free. 1055 uint num_free_regions() const { return _hrm.num_free_regions(); } 1056 1057 MemoryUsage get_auxiliary_data_memory_usage() const { 1058 return _hrm.get_auxiliary_data_memory_usage(); 1059 } 1060 1061 // The number of regions that are not completely free. 1062 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1063 1064 #ifdef ASSERT 1065 bool is_on_master_free_list(HeapRegion* hr) { 1066 return _hrm.is_free(hr); 1067 } 1068 #endif // ASSERT 1069 1070 // Wrapper for the region list operations that can be called from 1071 // methods outside this class. 1072 1073 void secondary_free_list_add(FreeRegionList* list) { 1074 _secondary_free_list.add_ordered(list); 1075 } 1076 1077 void append_secondary_free_list() { 1078 _hrm.insert_list_into_free_list(&_secondary_free_list); 1079 } 1080 1081 void append_secondary_free_list_if_not_empty_with_lock() { 1082 // If the secondary free list looks empty there's no reason to 1083 // take the lock and then try to append it. 1084 if (!_secondary_free_list.is_empty()) { 1085 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1086 append_secondary_free_list(); 1087 } 1088 } 1089 1090 inline void old_set_add(HeapRegion* hr); 1091 inline void old_set_remove(HeapRegion* hr); 1092 1093 size_t non_young_capacity_bytes() { 1094 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1095 } 1096 1097 void set_free_regions_coming(); 1098 void reset_free_regions_coming(); 1099 bool free_regions_coming() { return _free_regions_coming; } 1100 void wait_while_free_regions_coming(); 1101 1102 // Determine whether the given region is one that we are using as an 1103 // old GC alloc region. 1104 bool is_old_gc_alloc_region(HeapRegion* hr); 1105 1106 // Perform a collection of the heap; intended for use in implementing 1107 // "System.gc". This probably implies as full a collection as the 1108 // "CollectedHeap" supports. 1109 virtual void collect(GCCause::Cause cause); 1110 1111 virtual bool copy_allocation_context_stats(const jint* contexts, 1112 jlong* totals, 1113 jbyte* accuracy, 1114 jint len); 1115 1116 // True iff an evacuation has failed in the most-recent collection. 1117 bool evacuation_failed() { return _evacuation_failed; } 1118 1119 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1120 void prepend_to_freelist(FreeRegionList* list); 1121 void decrement_summary_bytes(size_t bytes); 1122 1123 virtual bool is_in(const void* p) const; 1124 #ifdef ASSERT 1125 // Returns whether p is in one of the available areas of the heap. Slow but 1126 // extensive version. 1127 bool is_in_exact(const void* p) const; 1128 #endif 1129 1130 // Return "TRUE" iff the given object address is within the collection 1131 // set. Slow implementation. 1132 bool obj_in_cs(oop obj); 1133 1134 inline bool is_in_cset(const HeapRegion *hr); 1135 inline bool is_in_cset(oop obj); 1136 1137 inline bool is_in_cset_or_humongous(const oop obj); 1138 1139 private: 1140 // This array is used for a quick test on whether a reference points into 1141 // the collection set or not. Each of the array's elements denotes whether the 1142 // corresponding region is in the collection set or not. 1143 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1144 1145 public: 1146 1147 inline InCSetState in_cset_state(const oop obj); 1148 1149 // Return "TRUE" iff the given object address is in the reserved 1150 // region of g1. 1151 bool is_in_g1_reserved(const void* p) const { 1152 return _hrm.reserved().contains(p); 1153 } 1154 1155 // Returns a MemRegion that corresponds to the space that has been 1156 // reserved for the heap 1157 MemRegion g1_reserved() const { 1158 return _hrm.reserved(); 1159 } 1160 1161 virtual bool is_in_closed_subset(const void* p) const; 1162 1163 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1164 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1165 } 1166 1167 // This resets the card table to all zeros. It is used after 1168 // a collection pause which used the card table to claim cards. 1169 void cleanUpCardTable(); 1170 1171 // Iteration functions. 1172 1173 // Iterate over all objects, calling "cl.do_object" on each. 1174 virtual void object_iterate(ObjectClosure* cl); 1175 1176 virtual void safe_object_iterate(ObjectClosure* cl) { 1177 object_iterate(cl); 1178 } 1179 1180 // Iterate over heap regions, in address order, terminating the 1181 // iteration early if the "doHeapRegion" method returns "true". 1182 void heap_region_iterate(HeapRegionClosure* blk) const; 1183 1184 // Return the region with the given index. It assumes the index is valid. 1185 inline HeapRegion* region_at(uint index) const; 1186 1187 // Return the next region (by index) that is part of the same 1188 // humongous object that hr is part of. 1189 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1190 1191 // Calculate the region index of the given address. Given address must be 1192 // within the heap. 1193 inline uint addr_to_region(HeapWord* addr) const; 1194 1195 inline HeapWord* bottom_addr_for_region(uint index) const; 1196 1197 // Iterate over the heap regions in parallel. Assumes that this will be called 1198 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1199 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1200 // to each of the regions, by attempting to claim the region using the 1201 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1202 // region. The concurrent argument should be set to true if iteration is 1203 // performed concurrently, during which no assumptions are made for consistent 1204 // attributes of the heap regions (as they might be modified while iterating). 1205 void heap_region_par_iterate(HeapRegionClosure* cl, 1206 uint worker_id, 1207 HeapRegionClaimer* hrclaimer, 1208 bool concurrent = false) const; 1209 1210 // Clear the cached cset start regions and (more importantly) 1211 // the time stamps. Called when we reset the GC time stamp. 1212 void clear_cset_start_regions(); 1213 1214 // Given the id of a worker, obtain or calculate a suitable 1215 // starting region for iterating over the current collection set. 1216 HeapRegion* start_cset_region_for_worker(uint worker_i); 1217 1218 // Iterate over the regions (if any) in the current collection set. 1219 void collection_set_iterate(HeapRegionClosure* blk); 1220 1221 // As above but starting from region r 1222 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 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 YoungList* young_list() const { return _young_list; } 1328 1329 uint old_regions_count() const { return _old_set.length(); } 1330 1331 uint humongous_regions_count() const { return _humongous_set.length(); } 1332 1333 // debugging 1334 bool check_young_list_well_formed() { 1335 return _young_list->check_list_well_formed(); 1336 } 1337 1338 bool check_young_list_empty(bool check_heap); 1339 1340 // *** Stuff related to concurrent marking. It's not clear to me that so 1341 // many of these need to be public. 1342 1343 // The functions below are helper functions that a subclass of 1344 // "CollectedHeap" can use in the implementation of its virtual 1345 // functions. 1346 // This performs a concurrent marking of the live objects in a 1347 // bitmap off to the side. 1348 void doConcurrentMark(); 1349 1350 bool isMarkedPrev(oop obj) const; 1351 bool isMarkedNext(oop obj) const; 1352 1353 // Determine if an object is dead, given the object and also 1354 // the region to which the object belongs. An object is dead 1355 // iff a) it was not allocated since the last mark, b) it 1356 // is not marked, and c) it is not in an archive region. 1357 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1358 return 1359 !hr->obj_allocated_since_prev_marking(obj) && 1360 !isMarkedPrev(obj) && 1361 !hr->is_archive(); 1362 } 1363 1364 // This function returns true when an object has been 1365 // around since the previous marking and hasn't yet 1366 // been marked during this marking, and is not in an archive region. 1367 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1368 return 1369 !hr->obj_allocated_since_next_marking(obj) && 1370 !isMarkedNext(obj) && 1371 !hr->is_archive(); 1372 } 1373 1374 // Determine if an object is dead, given only the object itself. 1375 // This will find the region to which the object belongs and 1376 // then call the region version of the same function. 1377 1378 // Added if it is NULL it isn't dead. 1379 1380 inline bool is_obj_dead(const oop obj) const; 1381 1382 inline bool is_obj_ill(const oop obj) const; 1383 1384 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1385 1386 // Refinement 1387 1388 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1389 1390 // The dirty cards region list is used to record a subset of regions 1391 // whose cards need clearing. The list if populated during the 1392 // remembered set scanning and drained during the card table 1393 // cleanup. Although the methods are reentrant, population/draining 1394 // phases must not overlap. For synchronization purposes the last 1395 // element on the list points to itself. 1396 HeapRegion* _dirty_cards_region_list; 1397 void push_dirty_cards_region(HeapRegion* hr); 1398 HeapRegion* pop_dirty_cards_region(); 1399 1400 // Optimized nmethod scanning support routines 1401 1402 // Register the given nmethod with the G1 heap. 1403 virtual void register_nmethod(nmethod* nm); 1404 1405 // Unregister the given nmethod from the G1 heap. 1406 virtual void unregister_nmethod(nmethod* nm); 1407 1408 // Free up superfluous code root memory. 1409 void purge_code_root_memory(); 1410 1411 // Rebuild the strong code root lists for each region 1412 // after a full GC. 1413 void rebuild_strong_code_roots(); 1414 1415 // Delete entries for dead interned string and clean up unreferenced symbols 1416 // in symbol table, possibly in parallel. 1417 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1418 1419 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1420 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1421 1422 // Redirty logged cards in the refinement queue. 1423 void redirty_logged_cards(); 1424 // Verification 1425 1426 // Perform any cleanup actions necessary before allowing a verification. 1427 virtual void prepare_for_verify(); 1428 1429 // Perform verification. 1430 1431 // vo == UsePrevMarking -> use "prev" marking information, 1432 // vo == UseNextMarking -> use "next" marking information 1433 // vo == UseMarkWord -> use the mark word in the object header 1434 // 1435 // NOTE: Only the "prev" marking information is guaranteed to be 1436 // consistent most of the time, so most calls to this should use 1437 // vo == UsePrevMarking. 1438 // Currently, there is only one case where this is called with 1439 // vo == UseNextMarking, which is to verify the "next" marking 1440 // information at the end of remark. 1441 // Currently there is only one place where this is called with 1442 // vo == UseMarkWord, which is to verify the marking during a 1443 // full GC. 1444 void verify(VerifyOption vo); 1445 1446 // The methods below are here for convenience and dispatch the 1447 // appropriate method depending on value of the given VerifyOption 1448 // parameter. The values for that parameter, and their meanings, 1449 // are the same as those above. 1450 1451 bool is_obj_dead_cond(const oop obj, 1452 const HeapRegion* hr, 1453 const VerifyOption vo) const; 1454 1455 bool is_obj_dead_cond(const oop obj, 1456 const VerifyOption vo) const; 1457 1458 G1HeapSummary create_g1_heap_summary(); 1459 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1460 1461 // Printing 1462 private: 1463 void print_heap_regions() const; 1464 void print_regions_on(outputStream* st) const; 1465 1466 public: 1467 virtual void print_on(outputStream* st) const; 1468 virtual void print_extended_on(outputStream* st) const; 1469 virtual void print_on_error(outputStream* st) const; 1470 1471 virtual void print_gc_threads_on(outputStream* st) const; 1472 virtual void gc_threads_do(ThreadClosure* tc) const; 1473 1474 // Override 1475 void print_tracing_info() const; 1476 1477 // The following two methods are helpful for debugging RSet issues. 1478 void print_cset_rsets() PRODUCT_RETURN; 1479 void print_all_rsets() PRODUCT_RETURN; 1480 1481 public: 1482 size_t pending_card_num(); 1483 1484 protected: 1485 size_t _max_heap_capacity; 1486 }; 1487 1488 class G1ParEvacuateFollowersClosure : public VoidClosure { 1489 private: 1490 double _start_term; 1491 double _term_time; 1492 size_t _term_attempts; 1493 1494 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1495 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1496 protected: 1497 G1CollectedHeap* _g1h; 1498 G1ParScanThreadState* _par_scan_state; 1499 RefToScanQueueSet* _queues; 1500 ParallelTaskTerminator* _terminator; 1501 1502 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1503 RefToScanQueueSet* queues() { return _queues; } 1504 ParallelTaskTerminator* terminator() { return _terminator; } 1505 1506 public: 1507 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1508 G1ParScanThreadState* par_scan_state, 1509 RefToScanQueueSet* queues, 1510 ParallelTaskTerminator* terminator) 1511 : _g1h(g1h), _par_scan_state(par_scan_state), 1512 _queues(queues), _terminator(terminator), 1513 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1514 1515 void do_void(); 1516 1517 double term_time() const { return _term_time; } 1518 size_t term_attempts() const { return _term_attempts; } 1519 1520 private: 1521 inline bool offer_termination(); 1522 }; 1523 1524 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP