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