1 /* 2 * Copyright (c) 2001, 2013, 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_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc_implementation/g1/concurrentMark.hpp" 29 #include "gc_implementation/g1/evacuationInfo.hpp" 30 #include "gc_implementation/g1/g1AllocRegion.hpp" 31 #include "gc_implementation/g1/g1HRPrinter.hpp" 32 #include "gc_implementation/g1/g1MonitoringSupport.hpp" 33 #include "gc_implementation/g1/g1RemSet.hpp" 34 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp" 35 #include "gc_implementation/g1/g1YCTypes.hpp" 36 #include "gc_implementation/g1/heapRegionSeq.hpp" 37 #include "gc_implementation/g1/heapRegionSets.hpp" 38 #include "gc_implementation/shared/hSpaceCounters.hpp" 39 #include "gc_implementation/shared/parGCAllocBuffer.hpp" 40 #include "memory/barrierSet.hpp" 41 #include "memory/memRegion.hpp" 42 #include "memory/sharedHeap.hpp" 43 #include "utilities/stack.hpp" 44 45 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 46 // It uses the "Garbage First" heap organization and algorithm, which 47 // may combine concurrent marking with parallel, incremental compaction of 48 // heap subsets that will yield large amounts of garbage. 49 50 // Forward declarations 51 class HeapRegion; 52 class HRRSCleanupTask; 53 class GenerationSpec; 54 class OopsInHeapRegionClosure; 55 class G1KlassScanClosure; 56 class G1ScanHeapEvacClosure; 57 class ObjectClosure; 58 class SpaceClosure; 59 class CompactibleSpaceClosure; 60 class Space; 61 class G1CollectorPolicy; 62 class GenRemSet; 63 class G1RemSet; 64 class HeapRegionRemSetIterator; 65 class ConcurrentMark; 66 class ConcurrentMarkThread; 67 class ConcurrentG1Refine; 68 class ConcurrentGCTimer; 69 class GenerationCounters; 70 class STWGCTimer; 71 class G1NewTracer; 72 class G1OldTracer; 73 class EvacuationFailedInfo; 74 class nmethod; 75 76 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 77 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 78 79 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 80 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 81 82 enum GCAllocPurpose { 83 GCAllocForTenured, 84 GCAllocForSurvived, 85 GCAllocPurposeCount 86 }; 87 88 class YoungList : public CHeapObj<mtGC> { 89 private: 90 G1CollectedHeap* _g1h; 91 92 HeapRegion* _head; 93 94 HeapRegion* _survivor_head; 95 HeapRegion* _survivor_tail; 96 97 HeapRegion* _curr; 98 99 uint _length; 100 uint _survivor_length; 101 102 size_t _last_sampled_rs_lengths; 103 size_t _sampled_rs_lengths; 104 105 void empty_list(HeapRegion* list); 106 107 public: 108 YoungList(G1CollectedHeap* g1h); 109 110 void push_region(HeapRegion* hr); 111 void add_survivor_region(HeapRegion* hr); 112 113 void empty_list(); 114 bool is_empty() { return _length == 0; } 115 uint length() { return _length; } 116 uint survivor_length() { return _survivor_length; } 117 118 // Currently we do not keep track of the used byte sum for the 119 // young list and the survivors and it'd be quite a lot of work to 120 // do so. When we'll eventually replace the young list with 121 // instances of HeapRegionLinkedList we'll get that for free. So, 122 // we'll report the more accurate information then. 123 size_t eden_used_bytes() { 124 assert(length() >= survivor_length(), "invariant"); 125 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 126 } 127 size_t survivor_used_bytes() { 128 return (size_t) survivor_length() * HeapRegion::GrainBytes; 129 } 130 131 void rs_length_sampling_init(); 132 bool rs_length_sampling_more(); 133 void rs_length_sampling_next(); 134 135 void reset_sampled_info() { 136 _last_sampled_rs_lengths = 0; 137 } 138 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 139 140 // for development purposes 141 void reset_auxilary_lists(); 142 void clear() { _head = NULL; _length = 0; } 143 144 void clear_survivors() { 145 _survivor_head = NULL; 146 _survivor_tail = NULL; 147 _survivor_length = 0; 148 } 149 150 HeapRegion* first_region() { return _head; } 151 HeapRegion* first_survivor_region() { return _survivor_head; } 152 HeapRegion* last_survivor_region() { return _survivor_tail; } 153 154 // debugging 155 bool check_list_well_formed(); 156 bool check_list_empty(bool check_sample = true); 157 void print(); 158 }; 159 160 class MutatorAllocRegion : public G1AllocRegion { 161 protected: 162 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 163 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 164 public: 165 MutatorAllocRegion() 166 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 167 }; 168 169 class SurvivorGCAllocRegion : public G1AllocRegion { 170 protected: 171 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 172 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 173 public: 174 SurvivorGCAllocRegion() 175 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { } 176 }; 177 178 class OldGCAllocRegion : public G1AllocRegion { 179 protected: 180 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 181 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 182 public: 183 OldGCAllocRegion() 184 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { } 185 }; 186 187 // The G1 STW is alive closure. 188 // An instance is embedded into the G1CH and used as the 189 // (optional) _is_alive_non_header closure in the STW 190 // reference processor. It is also extensively used during 191 // reference processing during STW evacuation pauses. 192 class G1STWIsAliveClosure: public BoolObjectClosure { 193 G1CollectedHeap* _g1; 194 public: 195 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 196 bool do_object_b(oop p); 197 }; 198 199 class RefineCardTableEntryClosure; 200 201 class G1CollectedHeap : public SharedHeap { 202 friend class VM_G1CollectForAllocation; 203 friend class VM_G1CollectFull; 204 friend class VM_G1IncCollectionPause; 205 friend class VMStructs; 206 friend class MutatorAllocRegion; 207 friend class SurvivorGCAllocRegion; 208 friend class OldGCAllocRegion; 209 210 // Closures used in implementation. 211 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 212 friend class G1ParCopyClosure; 213 friend class G1IsAliveClosure; 214 friend class G1EvacuateFollowersClosure; 215 friend class G1ParScanThreadState; 216 friend class G1ParScanClosureSuper; 217 friend class G1ParEvacuateFollowersClosure; 218 friend class G1ParTask; 219 friend class G1FreeGarbageRegionClosure; 220 friend class RefineCardTableEntryClosure; 221 friend class G1PrepareCompactClosure; 222 friend class RegionSorter; 223 friend class RegionResetter; 224 friend class CountRCClosure; 225 friend class EvacPopObjClosure; 226 friend class G1ParCleanupCTTask; 227 228 // Other related classes. 229 friend class G1MarkSweep; 230 231 private: 232 // The one and only G1CollectedHeap, so static functions can find it. 233 static G1CollectedHeap* _g1h; 234 235 static size_t _humongous_object_threshold_in_words; 236 237 // Storage for the G1 heap. 238 VirtualSpace _g1_storage; 239 MemRegion _g1_reserved; 240 241 // The part of _g1_storage that is currently committed. 242 MemRegion _g1_committed; 243 244 // The master free list. It will satisfy all new region allocations. 245 MasterFreeRegionList _free_list; 246 247 // The secondary free list which contains regions that have been 248 // freed up during the cleanup process. This will be appended to the 249 // master free list when appropriate. 250 SecondaryFreeRegionList _secondary_free_list; 251 252 // It keeps track of the old regions. 253 MasterOldRegionSet _old_set; 254 255 // It keeps track of the humongous regions. 256 MasterHumongousRegionSet _humongous_set; 257 258 // The number of regions we could create by expansion. 259 uint _expansion_regions; 260 261 // The block offset table for the G1 heap. 262 G1BlockOffsetSharedArray* _bot_shared; 263 264 // Tears down the region sets / lists so that they are empty and the 265 // regions on the heap do not belong to a region set / list. The 266 // only exception is the humongous set which we leave unaltered. If 267 // free_list_only is true, it will only tear down the master free 268 // list. It is called before a Full GC (free_list_only == false) or 269 // before heap shrinking (free_list_only == true). 270 void tear_down_region_sets(bool free_list_only); 271 272 // Rebuilds the region sets / lists so that they are repopulated to 273 // reflect the contents of the heap. The only exception is the 274 // humongous set which was not torn down in the first place. If 275 // free_list_only is true, it will only rebuild the master free 276 // list. It is called after a Full GC (free_list_only == false) or 277 // after heap shrinking (free_list_only == true). 278 void rebuild_region_sets(bool free_list_only); 279 280 // The sequence of all heap regions in the heap. 281 HeapRegionSeq _hrs; 282 283 // Alloc region used to satisfy mutator allocation requests. 284 MutatorAllocRegion _mutator_alloc_region; 285 286 // Alloc region used to satisfy allocation requests by the GC for 287 // survivor objects. 288 SurvivorGCAllocRegion _survivor_gc_alloc_region; 289 290 // PLAB sizing policy for survivors. 291 PLABStats _survivor_plab_stats; 292 293 // Alloc region used to satisfy allocation requests by the GC for 294 // old objects. 295 OldGCAllocRegion _old_gc_alloc_region; 296 297 // PLAB sizing policy for tenured objects. 298 PLABStats _old_plab_stats; 299 300 PLABStats* stats_for_purpose(GCAllocPurpose purpose) { 301 PLABStats* stats = NULL; 302 303 switch (purpose) { 304 case GCAllocForSurvived: 305 stats = &_survivor_plab_stats; 306 break; 307 case GCAllocForTenured: 308 stats = &_old_plab_stats; 309 break; 310 default: 311 assert(false, "unrecognized GCAllocPurpose"); 312 } 313 314 return stats; 315 } 316 317 // The last old region we allocated to during the last GC. 318 // Typically, it is not full so we should re-use it during the next GC. 319 HeapRegion* _retained_old_gc_alloc_region; 320 321 // It specifies whether we should attempt to expand the heap after a 322 // region allocation failure. If heap expansion fails we set this to 323 // false so that we don't re-attempt the heap expansion (it's likely 324 // that subsequent expansion attempts will also fail if one fails). 325 // Currently, it is only consulted during GC and it's reset at the 326 // start of each GC. 327 bool _expand_heap_after_alloc_failure; 328 329 // It resets the mutator alloc region before new allocations can take place. 330 void init_mutator_alloc_region(); 331 332 // It releases the mutator alloc region. 333 void release_mutator_alloc_region(); 334 335 // It initializes the GC alloc regions at the start of a GC. 336 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 337 338 // It releases the GC alloc regions at the end of a GC. 339 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 340 341 // It does any cleanup that needs to be done on the GC alloc regions 342 // before a Full GC. 343 void abandon_gc_alloc_regions(); 344 345 // Helper for monitoring and management support. 346 G1MonitoringSupport* _g1mm; 347 348 // Determines PLAB size for a particular allocation purpose. 349 size_t desired_plab_sz(GCAllocPurpose purpose); 350 351 // Outside of GC pauses, the number of bytes used in all regions other 352 // than the current allocation region. 353 size_t _summary_bytes_used; 354 355 // This is used for a quick test on whether a reference points into 356 // the collection set or not. Basically, we have an array, with one 357 // byte per region, and that byte denotes whether the corresponding 358 // region is in the collection set or not. The entry corresponding 359 // the bottom of the heap, i.e., region 0, is pointed to by 360 // _in_cset_fast_test_base. The _in_cset_fast_test field has been 361 // biased so that it actually points to address 0 of the address 362 // space, to make the test as fast as possible (we can simply shift 363 // the address to address into it, instead of having to subtract the 364 // bottom of the heap from the address before shifting it; basically 365 // it works in the same way the card table works). 366 bool* _in_cset_fast_test; 367 368 // The allocated array used for the fast test on whether a reference 369 // points into the collection set or not. This field is also used to 370 // free the array. 371 bool* _in_cset_fast_test_base; 372 373 // The length of the _in_cset_fast_test_base array. 374 uint _in_cset_fast_test_length; 375 376 volatile unsigned _gc_time_stamp; 377 378 size_t* _surviving_young_words; 379 380 G1HRPrinter _hr_printer; 381 382 void setup_surviving_young_words(); 383 void update_surviving_young_words(size_t* surv_young_words); 384 void cleanup_surviving_young_words(); 385 386 // It decides whether an explicit GC should start a concurrent cycle 387 // instead of doing a STW GC. Currently, a concurrent cycle is 388 // explicitly started if: 389 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 390 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 391 // (c) cause == _g1_humongous_allocation 392 bool should_do_concurrent_full_gc(GCCause::Cause cause); 393 394 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 395 // concurrent cycles) we have started. 396 volatile unsigned int _old_marking_cycles_started; 397 398 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 399 // concurrent cycles) we have completed. 400 volatile unsigned int _old_marking_cycles_completed; 401 402 bool _concurrent_cycle_started; 403 404 // This is a non-product method that is helpful for testing. It is 405 // called at the end of a GC and artificially expands the heap by 406 // allocating a number of dead regions. This way we can induce very 407 // frequent marking cycles and stress the cleanup / concurrent 408 // cleanup code more (as all the regions that will be allocated by 409 // this method will be found dead by the marking cycle). 410 void allocate_dummy_regions() PRODUCT_RETURN; 411 412 // Clear RSets after a compaction. It also resets the GC time stamps. 413 void clear_rsets_post_compaction(); 414 415 // If the HR printer is active, dump the state of the regions in the 416 // heap after a compaction. 417 void print_hrs_post_compaction(); 418 419 double verify(bool guard, const char* msg); 420 void verify_before_gc(); 421 void verify_after_gc(); 422 423 void log_gc_header(); 424 void log_gc_footer(double pause_time_sec); 425 426 // These are macros so that, if the assert fires, we get the correct 427 // line number, file, etc. 428 429 #define heap_locking_asserts_err_msg(_extra_message_) \ 430 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 431 (_extra_message_), \ 432 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 433 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 434 BOOL_TO_STR(Thread::current()->is_VM_thread())) 435 436 #define assert_heap_locked() \ 437 do { \ 438 assert(Heap_lock->owned_by_self(), \ 439 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 440 } while (0) 441 442 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 443 do { \ 444 assert(Heap_lock->owned_by_self() || \ 445 (SafepointSynchronize::is_at_safepoint() && \ 446 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 447 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 448 "should be at a safepoint")); \ 449 } while (0) 450 451 #define assert_heap_locked_and_not_at_safepoint() \ 452 do { \ 453 assert(Heap_lock->owned_by_self() && \ 454 !SafepointSynchronize::is_at_safepoint(), \ 455 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 456 "should not be at a safepoint")); \ 457 } while (0) 458 459 #define assert_heap_not_locked() \ 460 do { \ 461 assert(!Heap_lock->owned_by_self(), \ 462 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 463 } while (0) 464 465 #define assert_heap_not_locked_and_not_at_safepoint() \ 466 do { \ 467 assert(!Heap_lock->owned_by_self() && \ 468 !SafepointSynchronize::is_at_safepoint(), \ 469 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 470 "should not be at a safepoint")); \ 471 } while (0) 472 473 #define assert_at_safepoint(_should_be_vm_thread_) \ 474 do { \ 475 assert(SafepointSynchronize::is_at_safepoint() && \ 476 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 477 heap_locking_asserts_err_msg("should be at a safepoint")); \ 478 } while (0) 479 480 #define assert_not_at_safepoint() \ 481 do { \ 482 assert(!SafepointSynchronize::is_at_safepoint(), \ 483 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 484 } while (0) 485 486 protected: 487 488 // The young region list. 489 YoungList* _young_list; 490 491 // The current policy object for the collector. 492 G1CollectorPolicy* _g1_policy; 493 494 // This is the second level of trying to allocate a new region. If 495 // new_region() didn't find a region on the free_list, this call will 496 // check whether there's anything available on the 497 // secondary_free_list and/or wait for more regions to appear on 498 // that list, if _free_regions_coming is set. 499 HeapRegion* new_region_try_secondary_free_list(); 500 501 // Try to allocate a single non-humongous HeapRegion sufficient for 502 // an allocation of the given word_size. If do_expand is true, 503 // attempt to expand the heap if necessary to satisfy the allocation 504 // request. 505 HeapRegion* new_region(size_t word_size, bool do_expand); 506 507 // Attempt to satisfy a humongous allocation request of the given 508 // size by finding a contiguous set of free regions of num_regions 509 // length and remove them from the master free list. Return the 510 // index of the first region or G1_NULL_HRS_INDEX if the search 511 // was unsuccessful. 512 uint humongous_obj_allocate_find_first(uint num_regions, 513 size_t word_size); 514 515 // Initialize a contiguous set of free regions of length num_regions 516 // and starting at index first so that they appear as a single 517 // humongous region. 518 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 519 uint num_regions, 520 size_t word_size); 521 522 // Attempt to allocate a humongous object of the given size. Return 523 // NULL if unsuccessful. 524 HeapWord* humongous_obj_allocate(size_t word_size); 525 526 // The following two methods, allocate_new_tlab() and 527 // mem_allocate(), are the two main entry points from the runtime 528 // into the G1's allocation routines. They have the following 529 // assumptions: 530 // 531 // * They should both be called outside safepoints. 532 // 533 // * They should both be called without holding the Heap_lock. 534 // 535 // * All allocation requests for new TLABs should go to 536 // allocate_new_tlab(). 537 // 538 // * All non-TLAB allocation requests should go to mem_allocate(). 539 // 540 // * If either call cannot satisfy the allocation request using the 541 // current allocating region, they will try to get a new one. If 542 // this fails, they will attempt to do an evacuation pause and 543 // retry the allocation. 544 // 545 // * If all allocation attempts fail, even after trying to schedule 546 // an evacuation pause, allocate_new_tlab() will return NULL, 547 // whereas mem_allocate() will attempt a heap expansion and/or 548 // schedule a Full GC. 549 // 550 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 551 // should never be called with word_size being humongous. All 552 // humongous allocation requests should go to mem_allocate() which 553 // will satisfy them with a special path. 554 555 virtual HeapWord* allocate_new_tlab(size_t word_size); 556 557 virtual HeapWord* mem_allocate(size_t word_size, 558 bool* gc_overhead_limit_was_exceeded); 559 560 // The following three methods take a gc_count_before_ret 561 // parameter which is used to return the GC count if the method 562 // returns NULL. Given that we are required to read the GC count 563 // while holding the Heap_lock, and these paths will take the 564 // Heap_lock at some point, it's easier to get them to read the GC 565 // count while holding the Heap_lock before they return NULL instead 566 // of the caller (namely: mem_allocate()) having to also take the 567 // Heap_lock just to read the GC count. 568 569 // First-level mutator allocation attempt: try to allocate out of 570 // the mutator alloc region without taking the Heap_lock. This 571 // should only be used for non-humongous allocations. 572 inline HeapWord* attempt_allocation(size_t word_size, 573 unsigned int* gc_count_before_ret, 574 int* gclocker_retry_count_ret); 575 576 // Second-level mutator allocation attempt: take the Heap_lock and 577 // retry the allocation attempt, potentially scheduling a GC 578 // pause. This should only be used for non-humongous allocations. 579 HeapWord* attempt_allocation_slow(size_t word_size, 580 unsigned int* gc_count_before_ret, 581 int* gclocker_retry_count_ret); 582 583 // Takes the Heap_lock and attempts a humongous allocation. It can 584 // potentially schedule a GC pause. 585 HeapWord* attempt_allocation_humongous(size_t word_size, 586 unsigned int* gc_count_before_ret, 587 int* gclocker_retry_count_ret); 588 589 // Allocation attempt that should be called during safepoints (e.g., 590 // at the end of a successful GC). expect_null_mutator_alloc_region 591 // specifies whether the mutator alloc region is expected to be NULL 592 // or not. 593 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 594 bool expect_null_mutator_alloc_region); 595 596 // It dirties the cards that cover the block so that so that the post 597 // write barrier never queues anything when updating objects on this 598 // block. It is assumed (and in fact we assert) that the block 599 // belongs to a young region. 600 inline void dirty_young_block(HeapWord* start, size_t word_size); 601 602 // Allocate blocks during garbage collection. Will ensure an 603 // allocation region, either by picking one or expanding the 604 // heap, and then allocate a block of the given size. The block 605 // may not be a humongous - it must fit into a single heap region. 606 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 607 608 // Ensure that no further allocations can happen in "r", bearing in mind 609 // that parallel threads might be attempting allocations. 610 void par_allocate_remaining_space(HeapRegion* r); 611 612 // Allocation attempt during GC for a survivor object / PLAB. 613 inline HeapWord* survivor_attempt_allocation(size_t word_size); 614 615 // Allocation attempt during GC for an old object / PLAB. 616 inline HeapWord* old_attempt_allocation(size_t word_size); 617 618 // These methods are the "callbacks" from the G1AllocRegion class. 619 620 // For mutator alloc regions. 621 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 622 void retire_mutator_alloc_region(HeapRegion* alloc_region, 623 size_t allocated_bytes); 624 625 // For GC alloc regions. 626 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 627 GCAllocPurpose ap); 628 void retire_gc_alloc_region(HeapRegion* alloc_region, 629 size_t allocated_bytes, GCAllocPurpose ap); 630 631 // - if explicit_gc is true, the GC is for a System.gc() or a heap 632 // inspection request and should collect the entire heap 633 // - if clear_all_soft_refs is true, all soft references should be 634 // cleared during the GC 635 // - if explicit_gc is false, word_size describes the allocation that 636 // the GC should attempt (at least) to satisfy 637 // - it returns false if it is unable to do the collection due to the 638 // GC locker being active, true otherwise 639 bool do_collection(bool explicit_gc, 640 bool clear_all_soft_refs, 641 size_t word_size); 642 643 // Callback from VM_G1CollectFull operation. 644 // Perform a full collection. 645 virtual void do_full_collection(bool clear_all_soft_refs); 646 647 // Resize the heap if necessary after a full collection. If this is 648 // after a collect-for allocation, "word_size" is the allocation size, 649 // and will be considered part of the used portion of the heap. 650 void resize_if_necessary_after_full_collection(size_t word_size); 651 652 // Callback from VM_G1CollectForAllocation operation. 653 // This function does everything necessary/possible to satisfy a 654 // failed allocation request (including collection, expansion, etc.) 655 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 656 657 // Attempting to expand the heap sufficiently 658 // to support an allocation of the given "word_size". If 659 // successful, perform the allocation and return the address of the 660 // allocated block, or else "NULL". 661 HeapWord* expand_and_allocate(size_t word_size); 662 663 // Process any reference objects discovered during 664 // an incremental evacuation pause. 665 void process_discovered_references(uint no_of_gc_workers); 666 667 // Enqueue any remaining discovered references 668 // after processing. 669 void enqueue_discovered_references(uint no_of_gc_workers); 670 671 public: 672 673 G1MonitoringSupport* g1mm() { 674 assert(_g1mm != NULL, "should have been initialized"); 675 return _g1mm; 676 } 677 678 // Expand the garbage-first heap by at least the given size (in bytes!). 679 // Returns true if the heap was expanded by the requested amount; 680 // false otherwise. 681 // (Rounds up to a HeapRegion boundary.) 682 bool expand(size_t expand_bytes); 683 684 // Do anything common to GC's. 685 virtual void gc_prologue(bool full); 686 virtual void gc_epilogue(bool full); 687 688 // We register a region with the fast "in collection set" test. We 689 // simply set to true the array slot corresponding to this region. 690 void register_region_with_in_cset_fast_test(HeapRegion* r) { 691 assert(_in_cset_fast_test_base != NULL, "sanity"); 692 assert(r->in_collection_set(), "invariant"); 693 uint index = r->hrs_index(); 694 assert(index < _in_cset_fast_test_length, "invariant"); 695 assert(!_in_cset_fast_test_base[index], "invariant"); 696 _in_cset_fast_test_base[index] = true; 697 } 698 699 // This is a fast test on whether a reference points into the 700 // collection set or not. It does not assume that the reference 701 // points into the heap; if it doesn't, it will return false. 702 bool in_cset_fast_test(oop obj) { 703 assert(_in_cset_fast_test != NULL, "sanity"); 704 if (_g1_committed.contains((HeapWord*) obj)) { 705 // no need to subtract the bottom of the heap from obj, 706 // _in_cset_fast_test is biased 707 uintx index = cast_from_oop<uintx>(obj) >> HeapRegion::LogOfHRGrainBytes; 708 bool ret = _in_cset_fast_test[index]; 709 // let's make sure the result is consistent with what the slower 710 // test returns 711 assert( ret || !obj_in_cs(obj), "sanity"); 712 assert(!ret || obj_in_cs(obj), "sanity"); 713 return ret; 714 } else { 715 return false; 716 } 717 } 718 719 void clear_cset_fast_test() { 720 assert(_in_cset_fast_test_base != NULL, "sanity"); 721 memset(_in_cset_fast_test_base, false, 722 (size_t) _in_cset_fast_test_length * sizeof(bool)); 723 } 724 725 // This is called at the start of either a concurrent cycle or a Full 726 // GC to update the number of old marking cycles started. 727 void increment_old_marking_cycles_started(); 728 729 // This is called at the end of either a concurrent cycle or a Full 730 // GC to update the number of old marking cycles completed. Those two 731 // can happen in a nested fashion, i.e., we start a concurrent 732 // cycle, a Full GC happens half-way through it which ends first, 733 // and then the cycle notices that a Full GC happened and ends 734 // too. The concurrent parameter is a boolean to help us do a bit 735 // tighter consistency checking in the method. If concurrent is 736 // false, the caller is the inner caller in the nesting (i.e., the 737 // Full GC). If concurrent is true, the caller is the outer caller 738 // in this nesting (i.e., the concurrent cycle). Further nesting is 739 // not currently supported. The end of this call also notifies 740 // the FullGCCount_lock in case a Java thread is waiting for a full 741 // GC to happen (e.g., it called System.gc() with 742 // +ExplicitGCInvokesConcurrent). 743 void increment_old_marking_cycles_completed(bool concurrent); 744 745 unsigned int old_marking_cycles_completed() { 746 return _old_marking_cycles_completed; 747 } 748 749 void register_concurrent_cycle_start(jlong start_time); 750 void register_concurrent_cycle_end(); 751 void trace_heap_after_concurrent_cycle(); 752 753 G1YCType yc_type(); 754 755 G1HRPrinter* hr_printer() { return &_hr_printer; } 756 757 protected: 758 759 // Shrink the garbage-first heap by at most the given size (in bytes!). 760 // (Rounds down to a HeapRegion boundary.) 761 virtual void shrink(size_t expand_bytes); 762 void shrink_helper(size_t expand_bytes); 763 764 #if TASKQUEUE_STATS 765 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 766 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 767 void reset_taskqueue_stats(); 768 #endif // TASKQUEUE_STATS 769 770 // Schedule the VM operation that will do an evacuation pause to 771 // satisfy an allocation request of word_size. *succeeded will 772 // return whether the VM operation was successful (it did do an 773 // evacuation pause) or not (another thread beat us to it or the GC 774 // locker was active). Given that we should not be holding the 775 // Heap_lock when we enter this method, we will pass the 776 // gc_count_before (i.e., total_collections()) as a parameter since 777 // it has to be read while holding the Heap_lock. Currently, both 778 // methods that call do_collection_pause() release the Heap_lock 779 // before the call, so it's easy to read gc_count_before just before. 780 HeapWord* do_collection_pause(size_t word_size, 781 unsigned int gc_count_before, 782 bool* succeeded, 783 GCCause::Cause gc_cause); 784 785 // The guts of the incremental collection pause, executed by the vm 786 // thread. It returns false if it is unable to do the collection due 787 // to the GC locker being active, true otherwise 788 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 789 790 // Actually do the work of evacuating the collection set. 791 void evacuate_collection_set(EvacuationInfo& evacuation_info); 792 793 // The g1 remembered set of the heap. 794 G1RemSet* _g1_rem_set; 795 796 // A set of cards that cover the objects for which the Rsets should be updated 797 // concurrently after the collection. 798 DirtyCardQueueSet _dirty_card_queue_set; 799 800 // The closure used to refine a single card. 801 RefineCardTableEntryClosure* _refine_cte_cl; 802 803 // A function to check the consistency of dirty card logs. 804 void check_ct_logs_at_safepoint(); 805 806 // A DirtyCardQueueSet that is used to hold cards that contain 807 // references into the current collection set. This is used to 808 // update the remembered sets of the regions in the collection 809 // set in the event of an evacuation failure. 810 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 811 812 // After a collection pause, make the regions in the CS into free 813 // regions. 814 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 815 816 // Abandon the current collection set without recording policy 817 // statistics or updating free lists. 818 void abandon_collection_set(HeapRegion* cs_head); 819 820 // Applies "scan_non_heap_roots" to roots outside the heap, 821 // "scan_rs" to roots inside the heap (having done "set_region" to 822 // indicate the region in which the root resides), 823 // and does "scan_metadata" If "scan_rs" is 824 // NULL, then this step is skipped. The "worker_i" 825 // param is for use with parallel roots processing, and should be 826 // the "i" of the calling parallel worker thread's work(i) function. 827 // In the sequential case this param will be ignored. 828 void g1_process_strong_roots(bool is_scavenging, 829 ScanningOption so, 830 OopClosure* scan_non_heap_roots, 831 OopsInHeapRegionClosure* scan_rs, 832 G1KlassScanClosure* scan_klasses, 833 int worker_i); 834 835 // Apply "blk" to all the weak roots of the system. These include 836 // JNI weak roots, the code cache, system dictionary, symbol table, 837 // string table, and referents of reachable weak refs. 838 void g1_process_weak_roots(OopClosure* root_closure); 839 840 // Frees a non-humongous region by initializing its contents and 841 // adding it to the free list that's passed as a parameter (this is 842 // usually a local list which will be appended to the master free 843 // list later). The used bytes of freed regions are accumulated in 844 // pre_used. If par is true, the region's RSet will not be freed 845 // up. The assumption is that this will be done later. 846 void free_region(HeapRegion* hr, 847 size_t* pre_used, 848 FreeRegionList* free_list, 849 bool par); 850 851 // Frees a humongous region by collapsing it into individual regions 852 // and calling free_region() for each of them. The freed regions 853 // will be added to the free list that's passed as a parameter (this 854 // is usually a local list which will be appended to the master free 855 // list later). The used bytes of freed regions are accumulated in 856 // pre_used. If par is true, the region's RSet will not be freed 857 // up. The assumption is that this will be done later. 858 void free_humongous_region(HeapRegion* hr, 859 size_t* pre_used, 860 FreeRegionList* free_list, 861 HumongousRegionSet* humongous_proxy_set, 862 bool par); 863 864 // Notifies all the necessary spaces that the committed space has 865 // been updated (either expanded or shrunk). It should be called 866 // after _g1_storage is updated. 867 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 868 869 // The concurrent marker (and the thread it runs in.) 870 ConcurrentMark* _cm; 871 ConcurrentMarkThread* _cmThread; 872 bool _mark_in_progress; 873 874 // The concurrent refiner. 875 ConcurrentG1Refine* _cg1r; 876 877 // The parallel task queues 878 RefToScanQueueSet *_task_queues; 879 880 // True iff a evacuation has failed in the current collection. 881 bool _evacuation_failed; 882 883 EvacuationFailedInfo* _evacuation_failed_info_array; 884 885 // Failed evacuations cause some logical from-space objects to have 886 // forwarding pointers to themselves. Reset them. 887 void remove_self_forwarding_pointers(); 888 889 // Together, these store an object with a preserved mark, and its mark value. 890 Stack<oop, mtGC> _objs_with_preserved_marks; 891 Stack<markOop, mtGC> _preserved_marks_of_objs; 892 893 // Preserve the mark of "obj", if necessary, in preparation for its mark 894 // word being overwritten with a self-forwarding-pointer. 895 void preserve_mark_if_necessary(oop obj, markOop m); 896 897 // The stack of evac-failure objects left to be scanned. 898 GrowableArray<oop>* _evac_failure_scan_stack; 899 // The closure to apply to evac-failure objects. 900 901 OopsInHeapRegionClosure* _evac_failure_closure; 902 // Set the field above. 903 void 904 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 905 _evac_failure_closure = evac_failure_closure; 906 } 907 908 // Push "obj" on the scan stack. 909 void push_on_evac_failure_scan_stack(oop obj); 910 // Process scan stack entries until the stack is empty. 911 void drain_evac_failure_scan_stack(); 912 // True iff an invocation of "drain_scan_stack" is in progress; to 913 // prevent unnecessary recursion. 914 bool _drain_in_progress; 915 916 // Do any necessary initialization for evacuation-failure handling. 917 // "cl" is the closure that will be used to process evac-failure 918 // objects. 919 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 920 // Do any necessary cleanup for evacuation-failure handling data 921 // structures. 922 void finalize_for_evac_failure(); 923 924 // An attempt to evacuate "obj" has failed; take necessary steps. 925 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 926 void handle_evacuation_failure_common(oop obj, markOop m); 927 928 #ifndef PRODUCT 929 // Support for forcing evacuation failures. Analogous to 930 // PromotionFailureALot for the other collectors. 931 932 // Records whether G1EvacuationFailureALot should be in effect 933 // for the current GC 934 bool _evacuation_failure_alot_for_current_gc; 935 936 // Used to record the GC number for interval checking when 937 // determining whether G1EvaucationFailureALot is in effect 938 // for the current GC. 939 size_t _evacuation_failure_alot_gc_number; 940 941 // Count of the number of evacuations between failures. 942 volatile size_t _evacuation_failure_alot_count; 943 944 // Set whether G1EvacuationFailureALot should be in effect 945 // for the current GC (based upon the type of GC and which 946 // command line flags are set); 947 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 948 bool during_initial_mark, 949 bool during_marking); 950 951 inline void set_evacuation_failure_alot_for_current_gc(); 952 953 // Return true if it's time to cause an evacuation failure. 954 inline bool evacuation_should_fail(); 955 956 // Reset the G1EvacuationFailureALot counters. Should be called at 957 // the end of an evacuation pause in which an evacuation failure occurred. 958 inline void reset_evacuation_should_fail(); 959 #endif // !PRODUCT 960 961 // ("Weak") Reference processing support. 962 // 963 // G1 has 2 instances of the reference processor class. One 964 // (_ref_processor_cm) handles reference object discovery 965 // and subsequent processing during concurrent marking cycles. 966 // 967 // The other (_ref_processor_stw) handles reference object 968 // discovery and processing during full GCs and incremental 969 // evacuation pauses. 970 // 971 // During an incremental pause, reference discovery will be 972 // temporarily disabled for _ref_processor_cm and will be 973 // enabled for _ref_processor_stw. At the end of the evacuation 974 // pause references discovered by _ref_processor_stw will be 975 // processed and discovery will be disabled. The previous 976 // setting for reference object discovery for _ref_processor_cm 977 // will be re-instated. 978 // 979 // At the start of marking: 980 // * Discovery by the CM ref processor is verified to be inactive 981 // and it's discovered lists are empty. 982 // * Discovery by the CM ref processor is then enabled. 983 // 984 // At the end of marking: 985 // * Any references on the CM ref processor's discovered 986 // lists are processed (possibly MT). 987 // 988 // At the start of full GC we: 989 // * Disable discovery by the CM ref processor and 990 // empty CM ref processor's discovered lists 991 // (without processing any entries). 992 // * Verify that the STW ref processor is inactive and it's 993 // discovered lists are empty. 994 // * Temporarily set STW ref processor discovery as single threaded. 995 // * Temporarily clear the STW ref processor's _is_alive_non_header 996 // field. 997 // * Finally enable discovery by the STW ref processor. 998 // 999 // The STW ref processor is used to record any discovered 1000 // references during the full GC. 1001 // 1002 // At the end of a full GC we: 1003 // * Enqueue any reference objects discovered by the STW ref processor 1004 // that have non-live referents. This has the side-effect of 1005 // making the STW ref processor inactive by disabling discovery. 1006 // * Verify that the CM ref processor is still inactive 1007 // and no references have been placed on it's discovered 1008 // lists (also checked as a precondition during initial marking). 1009 1010 // The (stw) reference processor... 1011 ReferenceProcessor* _ref_processor_stw; 1012 1013 STWGCTimer* _gc_timer_stw; 1014 ConcurrentGCTimer* _gc_timer_cm; 1015 1016 G1OldTracer* _gc_tracer_cm; 1017 G1NewTracer* _gc_tracer_stw; 1018 1019 // During reference object discovery, the _is_alive_non_header 1020 // closure (if non-null) is applied to the referent object to 1021 // determine whether the referent is live. If so then the 1022 // reference object does not need to be 'discovered' and can 1023 // be treated as a regular oop. This has the benefit of reducing 1024 // the number of 'discovered' reference objects that need to 1025 // be processed. 1026 // 1027 // Instance of the is_alive closure for embedding into the 1028 // STW reference processor as the _is_alive_non_header field. 1029 // Supplying a value for the _is_alive_non_header field is 1030 // optional but doing so prevents unnecessary additions to 1031 // the discovered lists during reference discovery. 1032 G1STWIsAliveClosure _is_alive_closure_stw; 1033 1034 // The (concurrent marking) reference processor... 1035 ReferenceProcessor* _ref_processor_cm; 1036 1037 // Instance of the concurrent mark is_alive closure for embedding 1038 // into the Concurrent Marking reference processor as the 1039 // _is_alive_non_header field. Supplying a value for the 1040 // _is_alive_non_header field is optional but doing so prevents 1041 // unnecessary additions to the discovered lists during reference 1042 // discovery. 1043 G1CMIsAliveClosure _is_alive_closure_cm; 1044 1045 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1046 HeapRegion** _worker_cset_start_region; 1047 1048 // Time stamp to validate the regions recorded in the cache 1049 // used by G1CollectedHeap::start_cset_region_for_worker(). 1050 // The heap region entry for a given worker is valid iff 1051 // the associated time stamp value matches the current value 1052 // of G1CollectedHeap::_gc_time_stamp. 1053 unsigned int* _worker_cset_start_region_time_stamp; 1054 1055 enum G1H_process_strong_roots_tasks { 1056 G1H_PS_filter_satb_buffers, 1057 G1H_PS_refProcessor_oops_do, 1058 // Leave this one last. 1059 G1H_PS_NumElements 1060 }; 1061 1062 SubTasksDone* _process_strong_tasks; 1063 1064 volatile bool _free_regions_coming; 1065 1066 public: 1067 1068 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1069 1070 void set_refine_cte_cl_concurrency(bool concurrent); 1071 1072 RefToScanQueue *task_queue(int i) const; 1073 1074 // A set of cards where updates happened during the GC 1075 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1076 1077 // A DirtyCardQueueSet that is used to hold cards that contain 1078 // references into the current collection set. This is used to 1079 // update the remembered sets of the regions in the collection 1080 // set in the event of an evacuation failure. 1081 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1082 { return _into_cset_dirty_card_queue_set; } 1083 1084 // Create a G1CollectedHeap with the specified policy. 1085 // Must call the initialize method afterwards. 1086 // May not return if something goes wrong. 1087 G1CollectedHeap(G1CollectorPolicy* policy); 1088 1089 // Initialize the G1CollectedHeap to have the initial and 1090 // maximum sizes and remembered and barrier sets 1091 // specified by the policy object. 1092 jint initialize(); 1093 1094 // Return the (conservative) maximum heap alignment for any G1 heap 1095 static size_t conservative_max_heap_alignment(); 1096 1097 // Initialize weak reference processing. 1098 virtual void ref_processing_init(); 1099 1100 void set_par_threads(uint t) { 1101 SharedHeap::set_par_threads(t); 1102 // Done in SharedHeap but oddly there are 1103 // two _process_strong_tasks's in a G1CollectedHeap 1104 // so do it here too. 1105 _process_strong_tasks->set_n_threads(t); 1106 } 1107 1108 // Set _n_par_threads according to a policy TBD. 1109 void set_par_threads(); 1110 1111 void set_n_termination(int t) { 1112 _process_strong_tasks->set_n_threads(t); 1113 } 1114 1115 virtual CollectedHeap::Name kind() const { 1116 return CollectedHeap::G1CollectedHeap; 1117 } 1118 1119 // The current policy object for the collector. 1120 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1121 1122 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1123 1124 // Adaptive size policy. No such thing for g1. 1125 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1126 1127 // The rem set and barrier set. 1128 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1129 1130 unsigned get_gc_time_stamp() { 1131 return _gc_time_stamp; 1132 } 1133 1134 void reset_gc_time_stamp() { 1135 _gc_time_stamp = 0; 1136 OrderAccess::fence(); 1137 // Clear the cached CSet starting regions and time stamps. 1138 // Their validity is dependent on the GC timestamp. 1139 clear_cset_start_regions(); 1140 } 1141 1142 void check_gc_time_stamps() PRODUCT_RETURN; 1143 1144 void increment_gc_time_stamp() { 1145 ++_gc_time_stamp; 1146 OrderAccess::fence(); 1147 } 1148 1149 // Reset the given region's GC timestamp. If it's starts humongous, 1150 // also reset the GC timestamp of its corresponding 1151 // continues humongous regions too. 1152 void reset_gc_time_stamps(HeapRegion* hr); 1153 1154 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1155 DirtyCardQueue* into_cset_dcq, 1156 bool concurrent, int worker_i); 1157 1158 // The shared block offset table array. 1159 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1160 1161 // Reference Processing accessors 1162 1163 // The STW reference processor.... 1164 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1165 1166 // The Concurrent Marking reference processor... 1167 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1168 1169 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1170 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1171 1172 virtual size_t capacity() const; 1173 virtual size_t used() const; 1174 // This should be called when we're not holding the heap lock. The 1175 // result might be a bit inaccurate. 1176 size_t used_unlocked() const; 1177 size_t recalculate_used() const; 1178 1179 // These virtual functions do the actual allocation. 1180 // Some heaps may offer a contiguous region for shared non-blocking 1181 // allocation, via inlined code (by exporting the address of the top and 1182 // end fields defining the extent of the contiguous allocation region.) 1183 // But G1CollectedHeap doesn't yet support this. 1184 1185 // Return an estimate of the maximum allocation that could be performed 1186 // without triggering any collection or expansion activity. In a 1187 // generational collector, for example, this is probably the largest 1188 // allocation that could be supported (without expansion) in the youngest 1189 // generation. It is "unsafe" because no locks are taken; the result 1190 // should be treated as an approximation, not a guarantee, for use in 1191 // heuristic resizing decisions. 1192 virtual size_t unsafe_max_alloc(); 1193 1194 virtual bool is_maximal_no_gc() const { 1195 return _g1_storage.uncommitted_size() == 0; 1196 } 1197 1198 // The total number of regions in the heap. 1199 uint n_regions() { return _hrs.length(); } 1200 1201 // The max number of regions in the heap. 1202 uint max_regions() { return _hrs.max_length(); } 1203 1204 // The number of regions that are completely free. 1205 uint free_regions() { return _free_list.length(); } 1206 1207 // The number of regions that are not completely free. 1208 uint used_regions() { return n_regions() - free_regions(); } 1209 1210 // The number of regions available for "regular" expansion. 1211 uint expansion_regions() { return _expansion_regions; } 1212 1213 // Factory method for HeapRegion instances. It will return NULL if 1214 // the allocation fails. 1215 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1216 1217 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1218 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1219 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1220 void verify_dirty_young_regions() PRODUCT_RETURN; 1221 1222 // verify_region_sets() performs verification over the region 1223 // lists. It will be compiled in the product code to be used when 1224 // necessary (i.e., during heap verification). 1225 void verify_region_sets(); 1226 1227 // verify_region_sets_optional() is planted in the code for 1228 // list verification in non-product builds (and it can be enabled in 1229 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1230 #if HEAP_REGION_SET_FORCE_VERIFY 1231 void verify_region_sets_optional() { 1232 verify_region_sets(); 1233 } 1234 #else // HEAP_REGION_SET_FORCE_VERIFY 1235 void verify_region_sets_optional() { } 1236 #endif // HEAP_REGION_SET_FORCE_VERIFY 1237 1238 #ifdef ASSERT 1239 bool is_on_master_free_list(HeapRegion* hr) { 1240 return hr->containing_set() == &_free_list; 1241 } 1242 1243 bool is_in_humongous_set(HeapRegion* hr) { 1244 return hr->containing_set() == &_humongous_set; 1245 } 1246 #endif // ASSERT 1247 1248 // Wrapper for the region list operations that can be called from 1249 // methods outside this class. 1250 1251 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1252 _secondary_free_list.add_as_tail(list); 1253 } 1254 1255 void append_secondary_free_list() { 1256 _free_list.add_as_head(&_secondary_free_list); 1257 } 1258 1259 void append_secondary_free_list_if_not_empty_with_lock() { 1260 // If the secondary free list looks empty there's no reason to 1261 // take the lock and then try to append it. 1262 if (!_secondary_free_list.is_empty()) { 1263 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1264 append_secondary_free_list(); 1265 } 1266 } 1267 1268 void old_set_remove(HeapRegion* hr) { 1269 _old_set.remove(hr); 1270 } 1271 1272 size_t non_young_capacity_bytes() { 1273 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1274 } 1275 1276 void set_free_regions_coming(); 1277 void reset_free_regions_coming(); 1278 bool free_regions_coming() { return _free_regions_coming; } 1279 void wait_while_free_regions_coming(); 1280 1281 // Determine whether the given region is one that we are using as an 1282 // old GC alloc region. 1283 bool is_old_gc_alloc_region(HeapRegion* hr) { 1284 return hr == _retained_old_gc_alloc_region; 1285 } 1286 1287 // Perform a collection of the heap; intended for use in implementing 1288 // "System.gc". This probably implies as full a collection as the 1289 // "CollectedHeap" supports. 1290 virtual void collect(GCCause::Cause cause); 1291 1292 // The same as above but assume that the caller holds the Heap_lock. 1293 void collect_locked(GCCause::Cause cause); 1294 1295 // True iff an evacuation has failed in the most-recent collection. 1296 bool evacuation_failed() { return _evacuation_failed; } 1297 1298 // It will free a region if it has allocated objects in it that are 1299 // all dead. It calls either free_region() or 1300 // free_humongous_region() depending on the type of the region that 1301 // is passed to it. 1302 void free_region_if_empty(HeapRegion* hr, 1303 size_t* pre_used, 1304 FreeRegionList* free_list, 1305 OldRegionSet* old_proxy_set, 1306 HumongousRegionSet* humongous_proxy_set, 1307 HRRSCleanupTask* hrrs_cleanup_task, 1308 bool par); 1309 1310 // It appends the free list to the master free list and updates the 1311 // master humongous list according to the contents of the proxy 1312 // list. It also adjusts the total used bytes according to pre_used 1313 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1314 void update_sets_after_freeing_regions(size_t pre_used, 1315 FreeRegionList* free_list, 1316 OldRegionSet* old_proxy_set, 1317 HumongousRegionSet* humongous_proxy_set, 1318 bool par); 1319 1320 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1321 virtual bool is_in(const void* p) const; 1322 1323 // Return "TRUE" iff the given object address is within the collection 1324 // set. 1325 inline bool obj_in_cs(oop obj); 1326 1327 // Return "TRUE" iff the given object address is in the reserved 1328 // region of g1. 1329 bool is_in_g1_reserved(const void* p) const { 1330 return _g1_reserved.contains(p); 1331 } 1332 1333 // Returns a MemRegion that corresponds to the space that has been 1334 // reserved for the heap 1335 MemRegion g1_reserved() { 1336 return _g1_reserved; 1337 } 1338 1339 // Returns a MemRegion that corresponds to the space that has been 1340 // committed in the heap 1341 MemRegion g1_committed() { 1342 return _g1_committed; 1343 } 1344 1345 virtual bool is_in_closed_subset(const void* p) const; 1346 1347 G1SATBCardTableModRefBS* g1_barrier_set() { 1348 return (G1SATBCardTableModRefBS*) barrier_set(); 1349 } 1350 1351 // This resets the card table to all zeros. It is used after 1352 // a collection pause which used the card table to claim cards. 1353 void cleanUpCardTable(); 1354 1355 // Iteration functions. 1356 1357 // Iterate over all the ref-containing fields of all objects, calling 1358 // "cl.do_oop" on each. 1359 virtual void oop_iterate(ExtendedOopClosure* cl); 1360 1361 // Same as above, restricted to a memory region. 1362 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1363 1364 // Iterate over all objects, calling "cl.do_object" on each. 1365 virtual void object_iterate(ObjectClosure* cl); 1366 1367 virtual void safe_object_iterate(ObjectClosure* cl) { 1368 object_iterate(cl); 1369 } 1370 1371 // Iterate over all spaces in use in the heap, in ascending address order. 1372 virtual void space_iterate(SpaceClosure* cl); 1373 1374 // Iterate over heap regions, in address order, terminating the 1375 // iteration early if the "doHeapRegion" method returns "true". 1376 void heap_region_iterate(HeapRegionClosure* blk) const; 1377 1378 // Return the region with the given index. It assumes the index is valid. 1379 HeapRegion* region_at(uint index) const { return _hrs.at(index); } 1380 1381 // Divide the heap region sequence into "chunks" of some size (the number 1382 // of regions divided by the number of parallel threads times some 1383 // overpartition factor, currently 4). Assumes that this will be called 1384 // in parallel by ParallelGCThreads worker threads with discinct worker 1385 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1386 // calls will use the same "claim_value", and that that claim value is 1387 // different from the claim_value of any heap region before the start of 1388 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1389 // attempting to claim the first region in each chunk, and, if 1390 // successful, applying the closure to each region in the chunk (and 1391 // setting the claim value of the second and subsequent regions of the 1392 // chunk.) For now requires that "doHeapRegion" always returns "false", 1393 // i.e., that a closure never attempt to abort a traversal. 1394 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1395 uint worker, 1396 uint no_of_par_workers, 1397 jint claim_value); 1398 1399 // It resets all the region claim values to the default. 1400 void reset_heap_region_claim_values(); 1401 1402 // Resets the claim values of regions in the current 1403 // collection set to the default. 1404 void reset_cset_heap_region_claim_values(); 1405 1406 #ifdef ASSERT 1407 bool check_heap_region_claim_values(jint claim_value); 1408 1409 // Same as the routine above but only checks regions in the 1410 // current collection set. 1411 bool check_cset_heap_region_claim_values(jint claim_value); 1412 #endif // ASSERT 1413 1414 // Clear the cached cset start regions and (more importantly) 1415 // the time stamps. Called when we reset the GC time stamp. 1416 void clear_cset_start_regions(); 1417 1418 // Given the id of a worker, obtain or calculate a suitable 1419 // starting region for iterating over the current collection set. 1420 HeapRegion* start_cset_region_for_worker(int worker_i); 1421 1422 // This is a convenience method that is used by the 1423 // HeapRegionIterator classes to calculate the starting region for 1424 // each worker so that they do not all start from the same region. 1425 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1426 1427 // Iterate over the regions (if any) in the current collection set. 1428 void collection_set_iterate(HeapRegionClosure* blk); 1429 1430 // As above but starting from region r 1431 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1432 1433 // Returns the first (lowest address) compactible space in the heap. 1434 virtual CompactibleSpace* first_compactible_space(); 1435 1436 // A CollectedHeap will contain some number of spaces. This finds the 1437 // space containing a given address, or else returns NULL. 1438 virtual Space* space_containing(const void* addr) const; 1439 1440 // A G1CollectedHeap will contain some number of heap regions. This 1441 // finds the region containing a given address, or else returns NULL. 1442 template <class T> 1443 inline HeapRegion* heap_region_containing(const T addr) const; 1444 1445 // Like the above, but requires "addr" to be in the heap (to avoid a 1446 // null-check), and unlike the above, may return an continuing humongous 1447 // region. 1448 template <class T> 1449 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1450 1451 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1452 // each address in the (reserved) heap is a member of exactly 1453 // one block. The defining characteristic of a block is that it is 1454 // possible to find its size, and thus to progress forward to the next 1455 // block. (Blocks may be of different sizes.) Thus, blocks may 1456 // represent Java objects, or they might be free blocks in a 1457 // free-list-based heap (or subheap), as long as the two kinds are 1458 // distinguishable and the size of each is determinable. 1459 1460 // Returns the address of the start of the "block" that contains the 1461 // address "addr". We say "blocks" instead of "object" since some heaps 1462 // may not pack objects densely; a chunk may either be an object or a 1463 // non-object. 1464 virtual HeapWord* block_start(const void* addr) const; 1465 1466 // Requires "addr" to be the start of a chunk, and returns its size. 1467 // "addr + size" is required to be the start of a new chunk, or the end 1468 // of the active area of the heap. 1469 virtual size_t block_size(const HeapWord* addr) const; 1470 1471 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1472 // the block is an object. 1473 virtual bool block_is_obj(const HeapWord* addr) const; 1474 1475 // Does this heap support heap inspection? (+PrintClassHistogram) 1476 virtual bool supports_heap_inspection() const { return true; } 1477 1478 // Section on thread-local allocation buffers (TLABs) 1479 // See CollectedHeap for semantics. 1480 1481 virtual bool supports_tlab_allocation() const; 1482 virtual size_t tlab_capacity(Thread* thr) const; 1483 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1484 1485 // Can a compiler initialize a new object without store barriers? 1486 // This permission only extends from the creation of a new object 1487 // via a TLAB up to the first subsequent safepoint. If such permission 1488 // is granted for this heap type, the compiler promises to call 1489 // defer_store_barrier() below on any slow path allocation of 1490 // a new object for which such initializing store barriers will 1491 // have been elided. G1, like CMS, allows this, but should be 1492 // ready to provide a compensating write barrier as necessary 1493 // if that storage came out of a non-young region. The efficiency 1494 // of this implementation depends crucially on being able to 1495 // answer very efficiently in constant time whether a piece of 1496 // storage in the heap comes from a young region or not. 1497 // See ReduceInitialCardMarks. 1498 virtual bool can_elide_tlab_store_barriers() const { 1499 return true; 1500 } 1501 1502 virtual bool card_mark_must_follow_store() const { 1503 return true; 1504 } 1505 1506 bool is_in_young(const oop obj) { 1507 HeapRegion* hr = heap_region_containing(obj); 1508 return hr != NULL && hr->is_young(); 1509 } 1510 1511 #ifdef ASSERT 1512 virtual bool is_in_partial_collection(const void* p); 1513 #endif 1514 1515 virtual bool is_scavengable(const void* addr); 1516 1517 // We don't need barriers for initializing stores to objects 1518 // in the young gen: for the SATB pre-barrier, there is no 1519 // pre-value that needs to be remembered; for the remembered-set 1520 // update logging post-barrier, we don't maintain remembered set 1521 // information for young gen objects. 1522 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1523 return is_in_young(new_obj); 1524 } 1525 1526 // Returns "true" iff the given word_size is "very large". 1527 static bool isHumongous(size_t word_size) { 1528 // Note this has to be strictly greater-than as the TLABs 1529 // are capped at the humongous thresold and we want to 1530 // ensure that we don't try to allocate a TLAB as 1531 // humongous and that we don't allocate a humongous 1532 // object in a TLAB. 1533 return word_size > _humongous_object_threshold_in_words; 1534 } 1535 1536 // Update mod union table with the set of dirty cards. 1537 void updateModUnion(); 1538 1539 // Set the mod union bits corresponding to the given memRegion. Note 1540 // that this is always a safe operation, since it doesn't clear any 1541 // bits. 1542 void markModUnionRange(MemRegion mr); 1543 1544 // Records the fact that a marking phase is no longer in progress. 1545 void set_marking_complete() { 1546 _mark_in_progress = false; 1547 } 1548 void set_marking_started() { 1549 _mark_in_progress = true; 1550 } 1551 bool mark_in_progress() { 1552 return _mark_in_progress; 1553 } 1554 1555 // Print the maximum heap capacity. 1556 virtual size_t max_capacity() const; 1557 1558 virtual jlong millis_since_last_gc(); 1559 1560 1561 // Convenience function to be used in situations where the heap type can be 1562 // asserted to be this type. 1563 static G1CollectedHeap* heap(); 1564 1565 void set_region_short_lived_locked(HeapRegion* hr); 1566 // add appropriate methods for any other surv rate groups 1567 1568 YoungList* young_list() { return _young_list; } 1569 1570 // debugging 1571 bool check_young_list_well_formed() { 1572 return _young_list->check_list_well_formed(); 1573 } 1574 1575 bool check_young_list_empty(bool check_heap, 1576 bool check_sample = true); 1577 1578 // *** Stuff related to concurrent marking. It's not clear to me that so 1579 // many of these need to be public. 1580 1581 // The functions below are helper functions that a subclass of 1582 // "CollectedHeap" can use in the implementation of its virtual 1583 // functions. 1584 // This performs a concurrent marking of the live objects in a 1585 // bitmap off to the side. 1586 void doConcurrentMark(); 1587 1588 bool isMarkedPrev(oop obj) const; 1589 bool isMarkedNext(oop obj) const; 1590 1591 // Determine if an object is dead, given the object and also 1592 // the region to which the object belongs. An object is dead 1593 // iff a) it was not allocated since the last mark and b) it 1594 // is not marked. 1595 1596 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1597 return 1598 !hr->obj_allocated_since_prev_marking(obj) && 1599 !isMarkedPrev(obj); 1600 } 1601 1602 // This function returns true when an object has been 1603 // around since the previous marking and hasn't yet 1604 // been marked during this marking. 1605 1606 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1607 return 1608 !hr->obj_allocated_since_next_marking(obj) && 1609 !isMarkedNext(obj); 1610 } 1611 1612 // Determine if an object is dead, given only the object itself. 1613 // This will find the region to which the object belongs and 1614 // then call the region version of the same function. 1615 1616 // Added if it is NULL it isn't dead. 1617 1618 bool is_obj_dead(const oop obj) const { 1619 const HeapRegion* hr = heap_region_containing(obj); 1620 if (hr == NULL) { 1621 if (obj == NULL) return false; 1622 else return true; 1623 } 1624 else return is_obj_dead(obj, hr); 1625 } 1626 1627 bool is_obj_ill(const oop obj) const { 1628 const HeapRegion* hr = heap_region_containing(obj); 1629 if (hr == NULL) { 1630 if (obj == NULL) return false; 1631 else return true; 1632 } 1633 else return is_obj_ill(obj, hr); 1634 } 1635 1636 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1637 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1638 bool is_marked(oop obj, VerifyOption vo); 1639 const char* top_at_mark_start_str(VerifyOption vo); 1640 1641 ConcurrentMark* concurrent_mark() const { return _cm; } 1642 1643 // Refinement 1644 1645 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1646 1647 // The dirty cards region list is used to record a subset of regions 1648 // whose cards need clearing. The list if populated during the 1649 // remembered set scanning and drained during the card table 1650 // cleanup. Although the methods are reentrant, population/draining 1651 // phases must not overlap. For synchronization purposes the last 1652 // element on the list points to itself. 1653 HeapRegion* _dirty_cards_region_list; 1654 void push_dirty_cards_region(HeapRegion* hr); 1655 HeapRegion* pop_dirty_cards_region(); 1656 1657 // Optimized nmethod scanning support routines 1658 1659 // Register the given nmethod with the G1 heap 1660 virtual void register_nmethod(nmethod* nm); 1661 1662 // Unregister the given nmethod from the G1 heap 1663 virtual void unregister_nmethod(nmethod* nm); 1664 1665 // Migrate the nmethods in the code root lists of the regions 1666 // in the collection set to regions in to-space. In the event 1667 // of an evacuation failure, nmethods that reference objects 1668 // that were not successfullly evacuated are not migrated. 1669 void migrate_strong_code_roots(); 1670 1671 // During an initial mark pause, mark all the code roots that 1672 // point into regions *not* in the collection set. 1673 void mark_strong_code_roots(uint worker_id); 1674 1675 // Rebuild the stong code root lists for each region 1676 // after a full GC 1677 void rebuild_strong_code_roots(); 1678 1679 // Verification 1680 1681 // The following is just to alert the verification code 1682 // that a full collection has occurred and that the 1683 // remembered sets are no longer up to date. 1684 bool _full_collection; 1685 void set_full_collection() { _full_collection = true;} 1686 void clear_full_collection() {_full_collection = false;} 1687 bool full_collection() {return _full_collection;} 1688 1689 // Perform any cleanup actions necessary before allowing a verification. 1690 virtual void prepare_for_verify(); 1691 1692 // Perform verification. 1693 1694 // vo == UsePrevMarking -> use "prev" marking information, 1695 // vo == UseNextMarking -> use "next" marking information 1696 // vo == UseMarkWord -> use the mark word in the object header 1697 // 1698 // NOTE: Only the "prev" marking information is guaranteed to be 1699 // consistent most of the time, so most calls to this should use 1700 // vo == UsePrevMarking. 1701 // Currently, there is only one case where this is called with 1702 // vo == UseNextMarking, which is to verify the "next" marking 1703 // information at the end of remark. 1704 // Currently there is only one place where this is called with 1705 // vo == UseMarkWord, which is to verify the marking during a 1706 // full GC. 1707 void verify(bool silent, VerifyOption vo); 1708 1709 // Override; it uses the "prev" marking information 1710 virtual void verify(bool silent); 1711 1712 // The methods below are here for convenience and dispatch the 1713 // appropriate method depending on value of the given VerifyOption 1714 // parameter. The values for that parameter, and their meanings, 1715 // are the same as those above. 1716 1717 bool is_obj_dead_cond(const oop obj, 1718 const HeapRegion* hr, 1719 const VerifyOption vo) const { 1720 switch (vo) { 1721 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 1722 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 1723 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1724 default: ShouldNotReachHere(); 1725 } 1726 return false; // keep some compilers happy 1727 } 1728 1729 bool is_obj_dead_cond(const oop obj, 1730 const VerifyOption vo) const { 1731 switch (vo) { 1732 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 1733 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 1734 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1735 default: ShouldNotReachHere(); 1736 } 1737 return false; // keep some compilers happy 1738 } 1739 1740 // Printing 1741 1742 virtual void print_on(outputStream* st) const; 1743 virtual void print_extended_on(outputStream* st) const; 1744 virtual void print_on_error(outputStream* st) const; 1745 1746 virtual void print_gc_threads_on(outputStream* st) const; 1747 virtual void gc_threads_do(ThreadClosure* tc) const; 1748 1749 // Override 1750 void print_tracing_info() const; 1751 1752 // The following two methods are helpful for debugging RSet issues. 1753 void print_cset_rsets() PRODUCT_RETURN; 1754 void print_all_rsets() PRODUCT_RETURN; 1755 1756 public: 1757 void stop_conc_gc_threads(); 1758 1759 size_t pending_card_num(); 1760 size_t cards_scanned(); 1761 1762 protected: 1763 size_t _max_heap_capacity; 1764 }; 1765 1766 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1767 private: 1768 bool _retired; 1769 1770 public: 1771 G1ParGCAllocBuffer(size_t gclab_word_size); 1772 1773 void set_buf(HeapWord* buf) { 1774 ParGCAllocBuffer::set_buf(buf); 1775 _retired = false; 1776 } 1777 1778 void retire(bool end_of_gc, bool retain) { 1779 if (_retired) 1780 return; 1781 ParGCAllocBuffer::retire(end_of_gc, retain); 1782 _retired = true; 1783 } 1784 1785 bool is_retired() { 1786 return _retired; 1787 } 1788 }; 1789 1790 class G1ParGCAllocBufferContainer { 1791 protected: 1792 static int const _priority_max = 2; 1793 G1ParGCAllocBuffer* _priority_buffer[_priority_max]; 1794 1795 public: 1796 G1ParGCAllocBufferContainer(size_t gclab_word_size) { 1797 for (int pr = 0; pr < _priority_max; ++pr) { 1798 _priority_buffer[pr] = new G1ParGCAllocBuffer(gclab_word_size); 1799 } 1800 } 1801 1802 ~G1ParGCAllocBufferContainer() { 1803 for (int pr = 0; pr < _priority_max; ++pr) { 1804 assert(_priority_buffer[pr]->is_retired(), "alloc buffers should all retire at this point."); 1805 delete _priority_buffer[pr]; 1806 } 1807 } 1808 1809 HeapWord* allocate(size_t word_sz) { 1810 HeapWord* obj; 1811 for (int pr = 0; pr < _priority_max; ++pr) { 1812 obj = _priority_buffer[pr]->allocate(word_sz); 1813 if (obj != NULL) return obj; 1814 } 1815 return obj; 1816 } 1817 1818 bool contains(void* addr) { 1819 for (int pr = 0; pr < _priority_max; ++pr) { 1820 if (_priority_buffer[pr]->contains(addr)) return true; 1821 } 1822 return false; 1823 } 1824 1825 void undo_allocation(HeapWord* obj, size_t word_sz) { 1826 bool finish_undo; 1827 for (int pr = 0; pr < _priority_max; ++pr) { 1828 if (_priority_buffer[pr]->contains(obj)) { 1829 _priority_buffer[pr]->undo_allocation(obj, word_sz); 1830 finish_undo = true; 1831 } 1832 } 1833 if (!finish_undo) ShouldNotReachHere(); 1834 } 1835 1836 size_t words_remaining() { 1837 size_t result = 0; 1838 for (int pr = 0; pr < _priority_max; ++pr) { 1839 result += _priority_buffer[pr]->words_remaining(); 1840 } 1841 return result; 1842 } 1843 1844 size_t words_remaining_in_retired_buffer() { 1845 G1ParGCAllocBuffer* retired = _priority_buffer[0]; 1846 return retired->words_remaining(); 1847 } 1848 1849 void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) { 1850 for (int pr = 0; pr < _priority_max; ++pr) { 1851 _priority_buffer[pr]->flush_stats_and_retire(stats, end_of_gc, retain); 1852 } 1853 } 1854 1855 void update(bool end_of_gc, bool retain, HeapWord* buf, size_t word_sz) { 1856 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0]; 1857 retired_and_set->retire(end_of_gc, retain); 1858 retired_and_set->set_buf(buf); 1859 retired_and_set->set_word_size(word_sz); 1860 adjust_priority_order(); 1861 } 1862 1863 private: 1864 void adjust_priority_order() { 1865 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0]; 1866 1867 int last = _priority_max - 1; 1868 for (int pr = 0; pr < last; ++pr) { 1869 _priority_buffer[pr] = _priority_buffer[pr + 1]; 1870 } 1871 _priority_buffer[last] = retired_and_set; 1872 } 1873 }; 1874 1875 class G1ParScanThreadState : public StackObj { 1876 protected: 1877 G1CollectedHeap* _g1h; 1878 RefToScanQueue* _refs; 1879 DirtyCardQueue _dcq; 1880 G1SATBCardTableModRefBS* _ct_bs; 1881 G1RemSet* _g1_rem; 1882 1883 G1ParGCAllocBufferContainer _surviving_alloc_buffer; 1884 G1ParGCAllocBufferContainer _tenured_alloc_buffer; 1885 G1ParGCAllocBufferContainer* _alloc_buffers[GCAllocPurposeCount]; 1886 ageTable _age_table; 1887 1888 size_t _alloc_buffer_waste; 1889 size_t _undo_waste; 1890 1891 OopsInHeapRegionClosure* _evac_failure_cl; 1892 G1ParScanHeapEvacClosure* _evac_cl; 1893 G1ParScanPartialArrayClosure* _partial_scan_cl; 1894 1895 int _hash_seed; 1896 uint _queue_num; 1897 1898 size_t _term_attempts; 1899 1900 double _start; 1901 double _start_strong_roots; 1902 double _strong_roots_time; 1903 double _start_term; 1904 double _term_time; 1905 1906 // Map from young-age-index (0 == not young, 1 is youngest) to 1907 // surviving words. base is what we get back from the malloc call 1908 size_t* _surviving_young_words_base; 1909 // this points into the array, as we use the first few entries for padding 1910 size_t* _surviving_young_words; 1911 1912 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1913 1914 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1915 1916 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1917 1918 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1919 G1SATBCardTableModRefBS* ctbs() { return _ct_bs; } 1920 1921 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1922 if (!from->is_survivor()) { 1923 _g1_rem->par_write_ref(from, p, tid); 1924 } 1925 } 1926 1927 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1928 // If the new value of the field points to the same region or 1929 // is the to-space, we don't need to include it in the Rset updates. 1930 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1931 size_t card_index = ctbs()->index_for(p); 1932 // If the card hasn't been added to the buffer, do it. 1933 if (ctbs()->mark_card_deferred(card_index)) { 1934 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1935 } 1936 } 1937 } 1938 1939 public: 1940 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num); 1941 1942 ~G1ParScanThreadState() { 1943 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1944 } 1945 1946 RefToScanQueue* refs() { return _refs; } 1947 ageTable* age_table() { return &_age_table; } 1948 1949 G1ParGCAllocBufferContainer* alloc_buffer(GCAllocPurpose purpose) { 1950 return _alloc_buffers[purpose]; 1951 } 1952 1953 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1954 size_t undo_waste() const { return _undo_waste; } 1955 1956 #ifdef ASSERT 1957 bool verify_ref(narrowOop* ref) const; 1958 bool verify_ref(oop* ref) const; 1959 bool verify_task(StarTask ref) const; 1960 #endif // ASSERT 1961 1962 template <class T> void push_on_queue(T* ref) { 1963 assert(verify_ref(ref), "sanity"); 1964 refs()->push(ref); 1965 } 1966 1967 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1968 if (G1DeferredRSUpdate) { 1969 deferred_rs_update(from, p, tid); 1970 } else { 1971 immediate_rs_update(from, p, tid); 1972 } 1973 } 1974 1975 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1976 HeapWord* obj = NULL; 1977 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1978 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1979 G1ParGCAllocBufferContainer* alloc_buf = alloc_buffer(purpose); 1980 1981 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1982 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1983 1984 add_to_alloc_buffer_waste(alloc_buf->words_remaining_in_retired_buffer()); 1985 alloc_buf->update(false /* end_of_gc */, false /* retain */, buf, gclab_word_size); 1986 1987 obj = alloc_buf->allocate(word_sz); 1988 assert(obj != NULL, "buffer was definitely big enough..."); 1989 } else { 1990 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1991 } 1992 return obj; 1993 } 1994 1995 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1996 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1997 if (obj != NULL) return obj; 1998 return allocate_slow(purpose, word_sz); 1999 } 2000 2001 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 2002 if (alloc_buffer(purpose)->contains(obj)) { 2003 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 2004 "should contain whole object"); 2005 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 2006 } else { 2007 CollectedHeap::fill_with_object(obj, word_sz); 2008 add_to_undo_waste(word_sz); 2009 } 2010 } 2011 2012 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 2013 _evac_failure_cl = evac_failure_cl; 2014 } 2015 OopsInHeapRegionClosure* evac_failure_closure() { 2016 return _evac_failure_cl; 2017 } 2018 2019 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 2020 _evac_cl = evac_cl; 2021 } 2022 2023 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 2024 _partial_scan_cl = partial_scan_cl; 2025 } 2026 2027 int* hash_seed() { return &_hash_seed; } 2028 uint queue_num() { return _queue_num; } 2029 2030 size_t term_attempts() const { return _term_attempts; } 2031 void note_term_attempt() { _term_attempts++; } 2032 2033 void start_strong_roots() { 2034 _start_strong_roots = os::elapsedTime(); 2035 } 2036 void end_strong_roots() { 2037 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 2038 } 2039 double strong_roots_time() const { return _strong_roots_time; } 2040 2041 void start_term_time() { 2042 note_term_attempt(); 2043 _start_term = os::elapsedTime(); 2044 } 2045 void end_term_time() { 2046 _term_time += (os::elapsedTime() - _start_term); 2047 } 2048 double term_time() const { return _term_time; } 2049 2050 double elapsed_time() const { 2051 return os::elapsedTime() - _start; 2052 } 2053 2054 static void 2055 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 2056 void 2057 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 2058 2059 size_t* surviving_young_words() { 2060 // We add on to hide entry 0 which accumulates surviving words for 2061 // age -1 regions (i.e. non-young ones) 2062 return _surviving_young_words; 2063 } 2064 2065 void retire_alloc_buffers() { 2066 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 2067 size_t waste = _alloc_buffers[ap]->words_remaining(); 2068 add_to_alloc_buffer_waste(waste); 2069 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 2070 true /* end_of_gc */, 2071 false /* retain */); 2072 } 2073 } 2074 2075 template <class T> void deal_with_reference(T* ref_to_scan) { 2076 if (has_partial_array_mask(ref_to_scan)) { 2077 _partial_scan_cl->do_oop_nv(ref_to_scan); 2078 } else { 2079 // Note: we can use "raw" versions of "region_containing" because 2080 // "obj_to_scan" is definitely in the heap, and is not in a 2081 // humongous region. 2082 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 2083 _evac_cl->set_region(r); 2084 _evac_cl->do_oop_nv(ref_to_scan); 2085 } 2086 } 2087 2088 void deal_with_reference(StarTask ref) { 2089 assert(verify_task(ref), "sanity"); 2090 if (ref.is_narrow()) { 2091 deal_with_reference((narrowOop*)ref); 2092 } else { 2093 deal_with_reference((oop*)ref); 2094 } 2095 } 2096 2097 void trim_queue(); 2098 }; 2099 2100 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP