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 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. Assume that the reference 702 // points into the heap. 703 bool in_cset_fast_test(oop obj) { 704 assert(_in_cset_fast_test != NULL, "sanity"); 705 assert(_g1_committed.contains((HeapWord*) obj), err_msg("Given reference outside of heap, is "PTR_FORMAT, 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 } 716 717 void clear_cset_fast_test() { 718 assert(_in_cset_fast_test_base != NULL, "sanity"); 719 memset(_in_cset_fast_test_base, false, 720 (size_t) _in_cset_fast_test_length * sizeof(bool)); 721 } 722 723 // This is called at the start of either a concurrent cycle or a Full 724 // GC to update the number of old marking cycles started. 725 void increment_old_marking_cycles_started(); 726 727 // This is called at the end of either a concurrent cycle or a Full 728 // GC to update the number of old marking cycles completed. Those two 729 // can happen in a nested fashion, i.e., we start a concurrent 730 // cycle, a Full GC happens half-way through it which ends first, 731 // and then the cycle notices that a Full GC happened and ends 732 // too. The concurrent parameter is a boolean to help us do a bit 733 // tighter consistency checking in the method. If concurrent is 734 // false, the caller is the inner caller in the nesting (i.e., the 735 // Full GC). If concurrent is true, the caller is the outer caller 736 // in this nesting (i.e., the concurrent cycle). Further nesting is 737 // not currently supported. The end of this call also notifies 738 // the FullGCCount_lock in case a Java thread is waiting for a full 739 // GC to happen (e.g., it called System.gc() with 740 // +ExplicitGCInvokesConcurrent). 741 void increment_old_marking_cycles_completed(bool concurrent); 742 743 unsigned int old_marking_cycles_completed() { 744 return _old_marking_cycles_completed; 745 } 746 747 void register_concurrent_cycle_start(const Ticks& start_time); 748 void register_concurrent_cycle_end(); 749 void trace_heap_after_concurrent_cycle(); 750 751 G1YCType yc_type(); 752 753 G1HRPrinter* hr_printer() { return &_hr_printer; } 754 755 protected: 756 757 // Shrink the garbage-first heap by at most the given size (in bytes!). 758 // (Rounds down to a HeapRegion boundary.) 759 virtual void shrink(size_t expand_bytes); 760 void shrink_helper(size_t expand_bytes); 761 762 #if TASKQUEUE_STATS 763 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 764 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 765 void reset_taskqueue_stats(); 766 #endif // TASKQUEUE_STATS 767 768 // Schedule the VM operation that will do an evacuation pause to 769 // satisfy an allocation request of word_size. *succeeded will 770 // return whether the VM operation was successful (it did do an 771 // evacuation pause) or not (another thread beat us to it or the GC 772 // locker was active). Given that we should not be holding the 773 // Heap_lock when we enter this method, we will pass the 774 // gc_count_before (i.e., total_collections()) as a parameter since 775 // it has to be read while holding the Heap_lock. Currently, both 776 // methods that call do_collection_pause() release the Heap_lock 777 // before the call, so it's easy to read gc_count_before just before. 778 HeapWord* do_collection_pause(size_t word_size, 779 unsigned int gc_count_before, 780 bool* succeeded, 781 GCCause::Cause gc_cause); 782 783 // The guts of the incremental collection pause, executed by the vm 784 // thread. It returns false if it is unable to do the collection due 785 // to the GC locker being active, true otherwise 786 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 787 788 // Actually do the work of evacuating the collection set. 789 void evacuate_collection_set(EvacuationInfo& evacuation_info); 790 791 // The g1 remembered set of the heap. 792 G1RemSet* _g1_rem_set; 793 794 // A set of cards that cover the objects for which the Rsets should be updated 795 // concurrently after the collection. 796 DirtyCardQueueSet _dirty_card_queue_set; 797 798 // The closure used to refine a single card. 799 RefineCardTableEntryClosure* _refine_cte_cl; 800 801 // A function to check the consistency of dirty card logs. 802 void check_ct_logs_at_safepoint(); 803 804 // A DirtyCardQueueSet that is used to hold cards that contain 805 // references into the current collection set. This is used to 806 // update the remembered sets of the regions in the collection 807 // set in the event of an evacuation failure. 808 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 809 810 // After a collection pause, make the regions in the CS into free 811 // regions. 812 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 813 814 // Abandon the current collection set without recording policy 815 // statistics or updating free lists. 816 void abandon_collection_set(HeapRegion* cs_head); 817 818 // Applies "scan_non_heap_roots" to roots outside the heap, 819 // "scan_rs" to roots inside the heap (having done "set_region" to 820 // indicate the region in which the root resides), 821 // and does "scan_metadata" If "scan_rs" is 822 // NULL, then this step is skipped. The "worker_i" 823 // param is for use with parallel roots processing, and should be 824 // the "i" of the calling parallel worker thread's work(i) function. 825 // In the sequential case this param will be ignored. 826 void g1_process_strong_roots(bool is_scavenging, 827 ScanningOption so, 828 OopClosure* scan_non_heap_roots, 829 OopsInHeapRegionClosure* scan_rs, 830 G1KlassScanClosure* scan_klasses, 831 int worker_i); 832 833 // Frees a non-humongous region by initializing its contents and 834 // adding it to the free list that's passed as a parameter (this is 835 // usually a local list which will be appended to the master free 836 // list later). The used bytes of freed regions are accumulated in 837 // pre_used. If par is true, the region's RSet will not be freed 838 // up. The assumption is that this will be done later. 839 void free_region(HeapRegion* hr, 840 size_t* pre_used, 841 FreeRegionList* free_list, 842 bool par); 843 844 // Frees a humongous region by collapsing it into individual regions 845 // and calling free_region() for each of them. The freed regions 846 // will be added to the free list that's passed as a parameter (this 847 // is usually a local list which will be appended to the master free 848 // list later). The used bytes of freed regions are accumulated in 849 // pre_used. If par is true, the region's RSet will not be freed 850 // up. The assumption is that this will be done later. 851 void free_humongous_region(HeapRegion* hr, 852 size_t* pre_used, 853 FreeRegionList* free_list, 854 HumongousRegionSet* humongous_proxy_set, 855 bool par); 856 857 // Notifies all the necessary spaces that the committed space has 858 // been updated (either expanded or shrunk). It should be called 859 // after _g1_storage is updated. 860 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 861 862 // The concurrent marker (and the thread it runs in.) 863 ConcurrentMark* _cm; 864 ConcurrentMarkThread* _cmThread; 865 bool _mark_in_progress; 866 867 // The concurrent refiner. 868 ConcurrentG1Refine* _cg1r; 869 870 // The parallel task queues 871 RefToScanQueueSet *_task_queues; 872 873 // True iff a evacuation has failed in the current collection. 874 bool _evacuation_failed; 875 876 EvacuationFailedInfo* _evacuation_failed_info_array; 877 878 // Failed evacuations cause some logical from-space objects to have 879 // forwarding pointers to themselves. Reset them. 880 void remove_self_forwarding_pointers(); 881 882 // Together, these store an object with a preserved mark, and its mark value. 883 Stack<oop, mtGC> _objs_with_preserved_marks; 884 Stack<markOop, mtGC> _preserved_marks_of_objs; 885 886 // Preserve the mark of "obj", if necessary, in preparation for its mark 887 // word being overwritten with a self-forwarding-pointer. 888 void preserve_mark_if_necessary(oop obj, markOop m); 889 890 // The stack of evac-failure objects left to be scanned. 891 GrowableArray<oop>* _evac_failure_scan_stack; 892 // The closure to apply to evac-failure objects. 893 894 OopsInHeapRegionClosure* _evac_failure_closure; 895 // Set the field above. 896 void 897 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 898 _evac_failure_closure = evac_failure_closure; 899 } 900 901 // Push "obj" on the scan stack. 902 void push_on_evac_failure_scan_stack(oop obj); 903 // Process scan stack entries until the stack is empty. 904 void drain_evac_failure_scan_stack(); 905 // True iff an invocation of "drain_scan_stack" is in progress; to 906 // prevent unnecessary recursion. 907 bool _drain_in_progress; 908 909 // Do any necessary initialization for evacuation-failure handling. 910 // "cl" is the closure that will be used to process evac-failure 911 // objects. 912 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 913 // Do any necessary cleanup for evacuation-failure handling data 914 // structures. 915 void finalize_for_evac_failure(); 916 917 // An attempt to evacuate "obj" has failed; take necessary steps. 918 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 919 void handle_evacuation_failure_common(oop obj, markOop m); 920 921 #ifndef PRODUCT 922 // Support for forcing evacuation failures. Analogous to 923 // PromotionFailureALot for the other collectors. 924 925 // Records whether G1EvacuationFailureALot should be in effect 926 // for the current GC 927 bool _evacuation_failure_alot_for_current_gc; 928 929 // Used to record the GC number for interval checking when 930 // determining whether G1EvaucationFailureALot is in effect 931 // for the current GC. 932 size_t _evacuation_failure_alot_gc_number; 933 934 // Count of the number of evacuations between failures. 935 volatile size_t _evacuation_failure_alot_count; 936 937 // Set whether G1EvacuationFailureALot should be in effect 938 // for the current GC (based upon the type of GC and which 939 // command line flags are set); 940 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 941 bool during_initial_mark, 942 bool during_marking); 943 944 inline void set_evacuation_failure_alot_for_current_gc(); 945 946 // Return true if it's time to cause an evacuation failure. 947 inline bool evacuation_should_fail(); 948 949 // Reset the G1EvacuationFailureALot counters. Should be called at 950 // the end of an evacuation pause in which an evacuation failure occurred. 951 inline void reset_evacuation_should_fail(); 952 #endif // !PRODUCT 953 954 // ("Weak") Reference processing support. 955 // 956 // G1 has 2 instances of the reference processor class. One 957 // (_ref_processor_cm) handles reference object discovery 958 // and subsequent processing during concurrent marking cycles. 959 // 960 // The other (_ref_processor_stw) handles reference object 961 // discovery and processing during full GCs and incremental 962 // evacuation pauses. 963 // 964 // During an incremental pause, reference discovery will be 965 // temporarily disabled for _ref_processor_cm and will be 966 // enabled for _ref_processor_stw. At the end of the evacuation 967 // pause references discovered by _ref_processor_stw will be 968 // processed and discovery will be disabled. The previous 969 // setting for reference object discovery for _ref_processor_cm 970 // will be re-instated. 971 // 972 // At the start of marking: 973 // * Discovery by the CM ref processor is verified to be inactive 974 // and it's discovered lists are empty. 975 // * Discovery by the CM ref processor is then enabled. 976 // 977 // At the end of marking: 978 // * Any references on the CM ref processor's discovered 979 // lists are processed (possibly MT). 980 // 981 // At the start of full GC we: 982 // * Disable discovery by the CM ref processor and 983 // empty CM ref processor's discovered lists 984 // (without processing any entries). 985 // * Verify that the STW ref processor is inactive and it's 986 // discovered lists are empty. 987 // * Temporarily set STW ref processor discovery as single threaded. 988 // * Temporarily clear the STW ref processor's _is_alive_non_header 989 // field. 990 // * Finally enable discovery by the STW ref processor. 991 // 992 // The STW ref processor is used to record any discovered 993 // references during the full GC. 994 // 995 // At the end of a full GC we: 996 // * Enqueue any reference objects discovered by the STW ref processor 997 // that have non-live referents. This has the side-effect of 998 // making the STW ref processor inactive by disabling discovery. 999 // * Verify that the CM ref processor is still inactive 1000 // and no references have been placed on it's discovered 1001 // lists (also checked as a precondition during initial marking). 1002 1003 // The (stw) reference processor... 1004 ReferenceProcessor* _ref_processor_stw; 1005 1006 STWGCTimer* _gc_timer_stw; 1007 ConcurrentGCTimer* _gc_timer_cm; 1008 1009 G1OldTracer* _gc_tracer_cm; 1010 G1NewTracer* _gc_tracer_stw; 1011 1012 // During reference object discovery, the _is_alive_non_header 1013 // closure (if non-null) is applied to the referent object to 1014 // determine whether the referent is live. If so then the 1015 // reference object does not need to be 'discovered' and can 1016 // be treated as a regular oop. This has the benefit of reducing 1017 // the number of 'discovered' reference objects that need to 1018 // be processed. 1019 // 1020 // Instance of the is_alive closure for embedding into the 1021 // STW reference processor as the _is_alive_non_header field. 1022 // Supplying a value for the _is_alive_non_header field is 1023 // optional but doing so prevents unnecessary additions to 1024 // the discovered lists during reference discovery. 1025 G1STWIsAliveClosure _is_alive_closure_stw; 1026 1027 // The (concurrent marking) reference processor... 1028 ReferenceProcessor* _ref_processor_cm; 1029 1030 // Instance of the concurrent mark is_alive closure for embedding 1031 // into the Concurrent Marking reference processor as the 1032 // _is_alive_non_header field. Supplying a value for the 1033 // _is_alive_non_header field is optional but doing so prevents 1034 // unnecessary additions to the discovered lists during reference 1035 // discovery. 1036 G1CMIsAliveClosure _is_alive_closure_cm; 1037 1038 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1039 HeapRegion** _worker_cset_start_region; 1040 1041 // Time stamp to validate the regions recorded in the cache 1042 // used by G1CollectedHeap::start_cset_region_for_worker(). 1043 // The heap region entry for a given worker is valid iff 1044 // the associated time stamp value matches the current value 1045 // of G1CollectedHeap::_gc_time_stamp. 1046 unsigned int* _worker_cset_start_region_time_stamp; 1047 1048 enum G1H_process_strong_roots_tasks { 1049 G1H_PS_filter_satb_buffers, 1050 G1H_PS_refProcessor_oops_do, 1051 // Leave this one last. 1052 G1H_PS_NumElements 1053 }; 1054 1055 SubTasksDone* _process_strong_tasks; 1056 1057 volatile bool _free_regions_coming; 1058 1059 public: 1060 1061 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1062 1063 void set_refine_cte_cl_concurrency(bool concurrent); 1064 1065 RefToScanQueue *task_queue(int i) const; 1066 1067 // A set of cards where updates happened during the GC 1068 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1069 1070 // A DirtyCardQueueSet that is used to hold cards that contain 1071 // references into the current collection set. This is used to 1072 // update the remembered sets of the regions in the collection 1073 // set in the event of an evacuation failure. 1074 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1075 { return _into_cset_dirty_card_queue_set; } 1076 1077 // Create a G1CollectedHeap with the specified policy. 1078 // Must call the initialize method afterwards. 1079 // May not return if something goes wrong. 1080 G1CollectedHeap(G1CollectorPolicy* policy); 1081 1082 // Initialize the G1CollectedHeap to have the initial and 1083 // maximum sizes and remembered and barrier sets 1084 // specified by the policy object. 1085 jint initialize(); 1086 1087 // Return the (conservative) maximum heap alignment for any G1 heap 1088 static size_t conservative_max_heap_alignment(); 1089 1090 // Initialize weak reference processing. 1091 virtual void ref_processing_init(); 1092 1093 void set_par_threads(uint t) { 1094 SharedHeap::set_par_threads(t); 1095 // Done in SharedHeap but oddly there are 1096 // two _process_strong_tasks's in a G1CollectedHeap 1097 // so do it here too. 1098 _process_strong_tasks->set_n_threads(t); 1099 } 1100 1101 // Set _n_par_threads according to a policy TBD. 1102 void set_par_threads(); 1103 1104 void set_n_termination(int t) { 1105 _process_strong_tasks->set_n_threads(t); 1106 } 1107 1108 virtual CollectedHeap::Name kind() const { 1109 return CollectedHeap::G1CollectedHeap; 1110 } 1111 1112 // The current policy object for the collector. 1113 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1114 1115 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1116 1117 // Adaptive size policy. No such thing for g1. 1118 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1119 1120 // The rem set and barrier set. 1121 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1122 1123 unsigned get_gc_time_stamp() { 1124 return _gc_time_stamp; 1125 } 1126 1127 void reset_gc_time_stamp() { 1128 _gc_time_stamp = 0; 1129 OrderAccess::fence(); 1130 // Clear the cached CSet starting regions and time stamps. 1131 // Their validity is dependent on the GC timestamp. 1132 clear_cset_start_regions(); 1133 } 1134 1135 void check_gc_time_stamps() PRODUCT_RETURN; 1136 1137 void increment_gc_time_stamp() { 1138 ++_gc_time_stamp; 1139 OrderAccess::fence(); 1140 } 1141 1142 // Reset the given region's GC timestamp. If it's starts humongous, 1143 // also reset the GC timestamp of its corresponding 1144 // continues humongous regions too. 1145 void reset_gc_time_stamps(HeapRegion* hr); 1146 1147 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1148 DirtyCardQueue* into_cset_dcq, 1149 bool concurrent, int worker_i); 1150 1151 // The shared block offset table array. 1152 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1153 1154 // Reference Processing accessors 1155 1156 // The STW reference processor.... 1157 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1158 1159 // The Concurrent Marking reference processor... 1160 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1161 1162 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1163 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1164 1165 virtual size_t capacity() const; 1166 virtual size_t used() const; 1167 // This should be called when we're not holding the heap lock. The 1168 // result might be a bit inaccurate. 1169 size_t used_unlocked() const; 1170 size_t recalculate_used() const; 1171 1172 // These virtual functions do the actual allocation. 1173 // Some heaps may offer a contiguous region for shared non-blocking 1174 // allocation, via inlined code (by exporting the address of the top and 1175 // end fields defining the extent of the contiguous allocation region.) 1176 // But G1CollectedHeap doesn't yet support this. 1177 1178 virtual bool is_maximal_no_gc() const { 1179 return _g1_storage.uncommitted_size() == 0; 1180 } 1181 1182 // The total number of regions in the heap. 1183 uint n_regions() { return _hrs.length(); } 1184 1185 // The max number of regions in the heap. 1186 uint max_regions() { return _hrs.max_length(); } 1187 1188 // The number of regions that are completely free. 1189 uint free_regions() { return _free_list.length(); } 1190 1191 // The number of regions that are not completely free. 1192 uint used_regions() { return n_regions() - free_regions(); } 1193 1194 // The number of regions available for "regular" expansion. 1195 uint expansion_regions() { return _expansion_regions; } 1196 1197 // Factory method for HeapRegion instances. It will return NULL if 1198 // the allocation fails. 1199 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1200 1201 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1202 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1203 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1204 void verify_dirty_young_regions() PRODUCT_RETURN; 1205 1206 // verify_region_sets() performs verification over the region 1207 // lists. It will be compiled in the product code to be used when 1208 // necessary (i.e., during heap verification). 1209 void verify_region_sets(); 1210 1211 // verify_region_sets_optional() is planted in the code for 1212 // list verification in non-product builds (and it can be enabled in 1213 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1214 #if HEAP_REGION_SET_FORCE_VERIFY 1215 void verify_region_sets_optional() { 1216 verify_region_sets(); 1217 } 1218 #else // HEAP_REGION_SET_FORCE_VERIFY 1219 void verify_region_sets_optional() { } 1220 #endif // HEAP_REGION_SET_FORCE_VERIFY 1221 1222 #ifdef ASSERT 1223 bool is_on_master_free_list(HeapRegion* hr) { 1224 return hr->containing_set() == &_free_list; 1225 } 1226 1227 bool is_in_humongous_set(HeapRegion* hr) { 1228 return hr->containing_set() == &_humongous_set; 1229 } 1230 #endif // ASSERT 1231 1232 // Wrapper for the region list operations that can be called from 1233 // methods outside this class. 1234 1235 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1236 _secondary_free_list.add_as_tail(list); 1237 } 1238 1239 void append_secondary_free_list() { 1240 _free_list.add_as_head(&_secondary_free_list); 1241 } 1242 1243 void append_secondary_free_list_if_not_empty_with_lock() { 1244 // If the secondary free list looks empty there's no reason to 1245 // take the lock and then try to append it. 1246 if (!_secondary_free_list.is_empty()) { 1247 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1248 append_secondary_free_list(); 1249 } 1250 } 1251 1252 void old_set_remove(HeapRegion* hr) { 1253 _old_set.remove(hr); 1254 } 1255 1256 size_t non_young_capacity_bytes() { 1257 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1258 } 1259 1260 void set_free_regions_coming(); 1261 void reset_free_regions_coming(); 1262 bool free_regions_coming() { return _free_regions_coming; } 1263 void wait_while_free_regions_coming(); 1264 1265 // Determine whether the given region is one that we are using as an 1266 // old GC alloc region. 1267 bool is_old_gc_alloc_region(HeapRegion* hr) { 1268 return hr == _retained_old_gc_alloc_region; 1269 } 1270 1271 // Perform a collection of the heap; intended for use in implementing 1272 // "System.gc". This probably implies as full a collection as the 1273 // "CollectedHeap" supports. 1274 virtual void collect(GCCause::Cause cause); 1275 1276 // The same as above but assume that the caller holds the Heap_lock. 1277 void collect_locked(GCCause::Cause cause); 1278 1279 // True iff an evacuation has failed in the most-recent collection. 1280 bool evacuation_failed() { return _evacuation_failed; } 1281 1282 // It will free a region if it has allocated objects in it that are 1283 // all dead. It calls either free_region() or 1284 // free_humongous_region() depending on the type of the region that 1285 // is passed to it. 1286 void free_region_if_empty(HeapRegion* hr, 1287 size_t* pre_used, 1288 FreeRegionList* free_list, 1289 OldRegionSet* old_proxy_set, 1290 HumongousRegionSet* humongous_proxy_set, 1291 HRRSCleanupTask* hrrs_cleanup_task, 1292 bool par); 1293 1294 // It appends the free list to the master free list and updates the 1295 // master humongous list according to the contents of the proxy 1296 // list. It also adjusts the total used bytes according to pre_used 1297 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1298 void update_sets_after_freeing_regions(size_t pre_used, 1299 FreeRegionList* free_list, 1300 OldRegionSet* old_proxy_set, 1301 HumongousRegionSet* humongous_proxy_set, 1302 bool par); 1303 1304 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1305 virtual bool is_in(const void* p) const; 1306 1307 // Return "TRUE" iff the given object address is within the collection 1308 // set. 1309 inline bool obj_in_cs(oop obj); 1310 1311 // Return "TRUE" iff the given object address is in the reserved 1312 // region of g1. 1313 bool is_in_g1_reserved(const void* p) const { 1314 return _g1_reserved.contains(p); 1315 } 1316 1317 // Returns a MemRegion that corresponds to the space that has been 1318 // reserved for the heap 1319 MemRegion g1_reserved() { 1320 return _g1_reserved; 1321 } 1322 1323 // Returns a MemRegion that corresponds to the space that has been 1324 // committed in the heap 1325 MemRegion g1_committed() { 1326 return _g1_committed; 1327 } 1328 1329 virtual bool is_in_closed_subset(const void* p) const; 1330 1331 G1SATBCardTableModRefBS* g1_barrier_set() { 1332 return (G1SATBCardTableModRefBS*) barrier_set(); 1333 } 1334 1335 // This resets the card table to all zeros. It is used after 1336 // a collection pause which used the card table to claim cards. 1337 void cleanUpCardTable(); 1338 1339 // Iteration functions. 1340 1341 // Iterate over all the ref-containing fields of all objects, calling 1342 // "cl.do_oop" on each. 1343 virtual void oop_iterate(ExtendedOopClosure* cl); 1344 1345 // Same as above, restricted to a memory region. 1346 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1347 1348 // Iterate over all objects, calling "cl.do_object" on each. 1349 virtual void object_iterate(ObjectClosure* cl); 1350 1351 virtual void safe_object_iterate(ObjectClosure* cl) { 1352 object_iterate(cl); 1353 } 1354 1355 // Iterate over all spaces in use in the heap, in ascending address order. 1356 virtual void space_iterate(SpaceClosure* cl); 1357 1358 // Iterate over heap regions, in address order, terminating the 1359 // iteration early if the "doHeapRegion" method returns "true". 1360 void heap_region_iterate(HeapRegionClosure* blk) const; 1361 1362 // Return the region with the given index. It assumes the index is valid. 1363 HeapRegion* region_at(uint index) const { return _hrs.at(index); } 1364 1365 // Divide the heap region sequence into "chunks" of some size (the number 1366 // of regions divided by the number of parallel threads times some 1367 // overpartition factor, currently 4). Assumes that this will be called 1368 // in parallel by ParallelGCThreads worker threads with distinct worker 1369 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1370 // calls will use the same "claim_value", and that that claim value is 1371 // different from the claim_value of any heap region before the start of 1372 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1373 // attempting to claim the first region in each chunk, and, if 1374 // successful, applying the closure to each region in the chunk (and 1375 // setting the claim value of the second and subsequent regions of the 1376 // chunk.) For now requires that "doHeapRegion" always returns "false", 1377 // i.e., that a closure never attempt to abort a traversal. 1378 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1379 uint worker, 1380 uint no_of_par_workers, 1381 jint claim_value); 1382 1383 // It resets all the region claim values to the default. 1384 void reset_heap_region_claim_values(); 1385 1386 // Resets the claim values of regions in the current 1387 // collection set to the default. 1388 void reset_cset_heap_region_claim_values(); 1389 1390 #ifdef ASSERT 1391 bool check_heap_region_claim_values(jint claim_value); 1392 1393 // Same as the routine above but only checks regions in the 1394 // current collection set. 1395 bool check_cset_heap_region_claim_values(jint claim_value); 1396 #endif // ASSERT 1397 1398 // Clear the cached cset start regions and (more importantly) 1399 // the time stamps. Called when we reset the GC time stamp. 1400 void clear_cset_start_regions(); 1401 1402 // Given the id of a worker, obtain or calculate a suitable 1403 // starting region for iterating over the current collection set. 1404 HeapRegion* start_cset_region_for_worker(int worker_i); 1405 1406 // This is a convenience method that is used by the 1407 // HeapRegionIterator classes to calculate the starting region for 1408 // each worker so that they do not all start from the same region. 1409 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1410 1411 // Iterate over the regions (if any) in the current collection set. 1412 void collection_set_iterate(HeapRegionClosure* blk); 1413 1414 // As above but starting from region r 1415 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1416 1417 // Returns the first (lowest address) compactible space in the heap. 1418 virtual CompactibleSpace* first_compactible_space(); 1419 1420 // A CollectedHeap will contain some number of spaces. This finds the 1421 // space containing a given address, or else returns NULL. 1422 virtual Space* space_containing(const void* addr) const; 1423 1424 // A G1CollectedHeap will contain some number of heap regions. This 1425 // finds the region containing a given address, or else returns NULL. 1426 template <class T> 1427 inline HeapRegion* heap_region_containing(const T addr) const; 1428 1429 // Like the above, but requires "addr" to be in the heap (to avoid a 1430 // null-check), and unlike the above, may return an continuing humongous 1431 // region. 1432 template <class T> 1433 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1434 1435 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1436 // each address in the (reserved) heap is a member of exactly 1437 // one block. The defining characteristic of a block is that it is 1438 // possible to find its size, and thus to progress forward to the next 1439 // block. (Blocks may be of different sizes.) Thus, blocks may 1440 // represent Java objects, or they might be free blocks in a 1441 // free-list-based heap (or subheap), as long as the two kinds are 1442 // distinguishable and the size of each is determinable. 1443 1444 // Returns the address of the start of the "block" that contains the 1445 // address "addr". We say "blocks" instead of "object" since some heaps 1446 // may not pack objects densely; a chunk may either be an object or a 1447 // non-object. 1448 virtual HeapWord* block_start(const void* addr) const; 1449 1450 // Requires "addr" to be the start of a chunk, and returns its size. 1451 // "addr + size" is required to be the start of a new chunk, or the end 1452 // of the active area of the heap. 1453 virtual size_t block_size(const HeapWord* addr) const; 1454 1455 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1456 // the block is an object. 1457 virtual bool block_is_obj(const HeapWord* addr) const; 1458 1459 // Does this heap support heap inspection? (+PrintClassHistogram) 1460 virtual bool supports_heap_inspection() const { return true; } 1461 1462 // Section on thread-local allocation buffers (TLABs) 1463 // See CollectedHeap for semantics. 1464 1465 bool supports_tlab_allocation() const; 1466 size_t tlab_capacity(Thread* ignored) const; 1467 size_t tlab_used(Thread* ignored) const; 1468 size_t max_tlab_size() const; 1469 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1470 1471 // Can a compiler initialize a new object without store barriers? 1472 // This permission only extends from the creation of a new object 1473 // via a TLAB up to the first subsequent safepoint. If such permission 1474 // is granted for this heap type, the compiler promises to call 1475 // defer_store_barrier() below on any slow path allocation of 1476 // a new object for which such initializing store barriers will 1477 // have been elided. G1, like CMS, allows this, but should be 1478 // ready to provide a compensating write barrier as necessary 1479 // if that storage came out of a non-young region. The efficiency 1480 // of this implementation depends crucially on being able to 1481 // answer very efficiently in constant time whether a piece of 1482 // storage in the heap comes from a young region or not. 1483 // See ReduceInitialCardMarks. 1484 virtual bool can_elide_tlab_store_barriers() const { 1485 return true; 1486 } 1487 1488 virtual bool card_mark_must_follow_store() const { 1489 return true; 1490 } 1491 1492 bool is_in_young(const oop obj) { 1493 HeapRegion* hr = heap_region_containing(obj); 1494 return hr != NULL && hr->is_young(); 1495 } 1496 1497 #ifdef ASSERT 1498 virtual bool is_in_partial_collection(const void* p); 1499 #endif 1500 1501 virtual bool is_scavengable(const void* addr); 1502 1503 // We don't need barriers for initializing stores to objects 1504 // in the young gen: for the SATB pre-barrier, there is no 1505 // pre-value that needs to be remembered; for the remembered-set 1506 // update logging post-barrier, we don't maintain remembered set 1507 // information for young gen objects. 1508 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1509 return is_in_young(new_obj); 1510 } 1511 1512 // Returns "true" iff the given word_size is "very large". 1513 static bool isHumongous(size_t word_size) { 1514 // Note this has to be strictly greater-than as the TLABs 1515 // are capped at the humongous threshold and we want to 1516 // ensure that we don't try to allocate a TLAB as 1517 // humongous and that we don't allocate a humongous 1518 // object in a TLAB. 1519 return word_size > _humongous_object_threshold_in_words; 1520 } 1521 1522 // Update mod union table with the set of dirty cards. 1523 void updateModUnion(); 1524 1525 // Set the mod union bits corresponding to the given memRegion. Note 1526 // that this is always a safe operation, since it doesn't clear any 1527 // bits. 1528 void markModUnionRange(MemRegion mr); 1529 1530 // Records the fact that a marking phase is no longer in progress. 1531 void set_marking_complete() { 1532 _mark_in_progress = false; 1533 } 1534 void set_marking_started() { 1535 _mark_in_progress = true; 1536 } 1537 bool mark_in_progress() { 1538 return _mark_in_progress; 1539 } 1540 1541 // Print the maximum heap capacity. 1542 virtual size_t max_capacity() const; 1543 1544 virtual jlong millis_since_last_gc(); 1545 1546 1547 // Convenience function to be used in situations where the heap type can be 1548 // asserted to be this type. 1549 static G1CollectedHeap* heap(); 1550 1551 void set_region_short_lived_locked(HeapRegion* hr); 1552 // add appropriate methods for any other surv rate groups 1553 1554 YoungList* young_list() const { return _young_list; } 1555 1556 // debugging 1557 bool check_young_list_well_formed() { 1558 return _young_list->check_list_well_formed(); 1559 } 1560 1561 bool check_young_list_empty(bool check_heap, 1562 bool check_sample = true); 1563 1564 // *** Stuff related to concurrent marking. It's not clear to me that so 1565 // many of these need to be public. 1566 1567 // The functions below are helper functions that a subclass of 1568 // "CollectedHeap" can use in the implementation of its virtual 1569 // functions. 1570 // This performs a concurrent marking of the live objects in a 1571 // bitmap off to the side. 1572 void doConcurrentMark(); 1573 1574 bool isMarkedPrev(oop obj) const; 1575 bool isMarkedNext(oop obj) const; 1576 1577 // Determine if an object is dead, given the object and also 1578 // the region to which the object belongs. An object is dead 1579 // iff a) it was not allocated since the last mark and b) it 1580 // is not marked. 1581 1582 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1583 return 1584 !hr->obj_allocated_since_prev_marking(obj) && 1585 !isMarkedPrev(obj); 1586 } 1587 1588 // This function returns true when an object has been 1589 // around since the previous marking and hasn't yet 1590 // been marked during this marking. 1591 1592 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1593 return 1594 !hr->obj_allocated_since_next_marking(obj) && 1595 !isMarkedNext(obj); 1596 } 1597 1598 // Determine if an object is dead, given only the object itself. 1599 // This will find the region to which the object belongs and 1600 // then call the region version of the same function. 1601 1602 // Added if it is NULL it isn't dead. 1603 1604 bool is_obj_dead(const oop obj) const { 1605 const HeapRegion* hr = heap_region_containing(obj); 1606 if (hr == NULL) { 1607 if (obj == NULL) return false; 1608 else return true; 1609 } 1610 else return is_obj_dead(obj, hr); 1611 } 1612 1613 bool is_obj_ill(const oop obj) const { 1614 const HeapRegion* hr = heap_region_containing(obj); 1615 if (hr == NULL) { 1616 if (obj == NULL) return false; 1617 else return true; 1618 } 1619 else return is_obj_ill(obj, hr); 1620 } 1621 1622 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1623 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1624 bool is_marked(oop obj, VerifyOption vo); 1625 const char* top_at_mark_start_str(VerifyOption vo); 1626 1627 ConcurrentMark* concurrent_mark() const { return _cm; } 1628 1629 // Refinement 1630 1631 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1632 1633 // The dirty cards region list is used to record a subset of regions 1634 // whose cards need clearing. The list if populated during the 1635 // remembered set scanning and drained during the card table 1636 // cleanup. Although the methods are reentrant, population/draining 1637 // phases must not overlap. For synchronization purposes the last 1638 // element on the list points to itself. 1639 HeapRegion* _dirty_cards_region_list; 1640 void push_dirty_cards_region(HeapRegion* hr); 1641 HeapRegion* pop_dirty_cards_region(); 1642 1643 // Optimized nmethod scanning support routines 1644 1645 // Register the given nmethod with the G1 heap. 1646 virtual void register_nmethod(nmethod* nm); 1647 1648 // Unregister the given nmethod from the G1 heap. 1649 virtual void unregister_nmethod(nmethod* nm); 1650 1651 // Migrate the nmethods in the code root lists of the regions 1652 // in the collection set to regions in to-space. In the event 1653 // of an evacuation failure, nmethods that reference objects 1654 // that were not successfully evacuated are not migrated. 1655 void migrate_strong_code_roots(); 1656 1657 // During an initial mark pause, mark all the code roots that 1658 // point into regions *not* in the collection set. 1659 void mark_strong_code_roots(uint worker_id); 1660 1661 // Rebuild the strong code root lists for each region 1662 // after a full GC. 1663 void rebuild_strong_code_roots(); 1664 1665 // Delete entries for dead interned string and clean up unreferenced symbols 1666 // in symbol table, possibly in parallel. 1667 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1668 1669 // Verification 1670 1671 // The following is just to alert the verification code 1672 // that a full collection has occurred and that the 1673 // remembered sets are no longer up to date. 1674 bool _full_collection; 1675 void set_full_collection() { _full_collection = true;} 1676 void clear_full_collection() {_full_collection = false;} 1677 bool full_collection() {return _full_collection;} 1678 1679 // Perform any cleanup actions necessary before allowing a verification. 1680 virtual void prepare_for_verify(); 1681 1682 // Perform verification. 1683 1684 // vo == UsePrevMarking -> use "prev" marking information, 1685 // vo == UseNextMarking -> use "next" marking information 1686 // vo == UseMarkWord -> use the mark word in the object header 1687 // 1688 // NOTE: Only the "prev" marking information is guaranteed to be 1689 // consistent most of the time, so most calls to this should use 1690 // vo == UsePrevMarking. 1691 // Currently, there is only one case where this is called with 1692 // vo == UseNextMarking, which is to verify the "next" marking 1693 // information at the end of remark. 1694 // Currently there is only one place where this is called with 1695 // vo == UseMarkWord, which is to verify the marking during a 1696 // full GC. 1697 void verify(bool silent, VerifyOption vo); 1698 1699 // Override; it uses the "prev" marking information 1700 virtual void verify(bool silent); 1701 1702 // The methods below are here for convenience and dispatch the 1703 // appropriate method depending on value of the given VerifyOption 1704 // parameter. The values for that parameter, and their meanings, 1705 // are the same as those above. 1706 1707 bool is_obj_dead_cond(const oop obj, 1708 const HeapRegion* hr, 1709 const VerifyOption vo) const { 1710 switch (vo) { 1711 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 1712 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 1713 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1714 default: ShouldNotReachHere(); 1715 } 1716 return false; // keep some compilers happy 1717 } 1718 1719 bool is_obj_dead_cond(const oop obj, 1720 const VerifyOption vo) const { 1721 switch (vo) { 1722 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 1723 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 1724 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1725 default: ShouldNotReachHere(); 1726 } 1727 return false; // keep some compilers happy 1728 } 1729 1730 // Printing 1731 1732 virtual void print_on(outputStream* st) const; 1733 virtual void print_extended_on(outputStream* st) const; 1734 virtual void print_on_error(outputStream* st) const; 1735 1736 virtual void print_gc_threads_on(outputStream* st) const; 1737 virtual void gc_threads_do(ThreadClosure* tc) const; 1738 1739 // Override 1740 void print_tracing_info() const; 1741 1742 // The following two methods are helpful for debugging RSet issues. 1743 void print_cset_rsets() PRODUCT_RETURN; 1744 void print_all_rsets() PRODUCT_RETURN; 1745 1746 public: 1747 void stop_conc_gc_threads(); 1748 1749 size_t pending_card_num(); 1750 size_t cards_scanned(); 1751 1752 protected: 1753 size_t _max_heap_capacity; 1754 }; 1755 1756 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1757 private: 1758 bool _retired; 1759 1760 public: 1761 G1ParGCAllocBuffer(size_t gclab_word_size); 1762 1763 void set_buf(HeapWord* buf) { 1764 ParGCAllocBuffer::set_buf(buf); 1765 _retired = false; 1766 } 1767 1768 void retire(bool end_of_gc, bool retain) { 1769 if (_retired) 1770 return; 1771 ParGCAllocBuffer::retire(end_of_gc, retain); 1772 _retired = true; 1773 } 1774 1775 bool is_retired() { 1776 return _retired; 1777 } 1778 }; 1779 1780 class G1ParGCAllocBufferContainer { 1781 protected: 1782 static int const _priority_max = 2; 1783 G1ParGCAllocBuffer* _priority_buffer[_priority_max]; 1784 1785 public: 1786 G1ParGCAllocBufferContainer(size_t gclab_word_size) { 1787 for (int pr = 0; pr < _priority_max; ++pr) { 1788 _priority_buffer[pr] = new G1ParGCAllocBuffer(gclab_word_size); 1789 } 1790 } 1791 1792 ~G1ParGCAllocBufferContainer() { 1793 for (int pr = 0; pr < _priority_max; ++pr) { 1794 assert(_priority_buffer[pr]->is_retired(), "alloc buffers should all retire at this point."); 1795 delete _priority_buffer[pr]; 1796 } 1797 } 1798 1799 HeapWord* allocate(size_t word_sz) { 1800 HeapWord* obj; 1801 for (int pr = 0; pr < _priority_max; ++pr) { 1802 obj = _priority_buffer[pr]->allocate(word_sz); 1803 if (obj != NULL) return obj; 1804 } 1805 return obj; 1806 } 1807 1808 bool contains(void* addr) { 1809 for (int pr = 0; pr < _priority_max; ++pr) { 1810 if (_priority_buffer[pr]->contains(addr)) return true; 1811 } 1812 return false; 1813 } 1814 1815 void undo_allocation(HeapWord* obj, size_t word_sz) { 1816 bool finish_undo; 1817 for (int pr = 0; pr < _priority_max; ++pr) { 1818 if (_priority_buffer[pr]->contains(obj)) { 1819 _priority_buffer[pr]->undo_allocation(obj, word_sz); 1820 finish_undo = true; 1821 } 1822 } 1823 if (!finish_undo) ShouldNotReachHere(); 1824 } 1825 1826 size_t words_remaining() { 1827 size_t result = 0; 1828 for (int pr = 0; pr < _priority_max; ++pr) { 1829 result += _priority_buffer[pr]->words_remaining(); 1830 } 1831 return result; 1832 } 1833 1834 size_t words_remaining_in_retired_buffer() { 1835 G1ParGCAllocBuffer* retired = _priority_buffer[0]; 1836 return retired->words_remaining(); 1837 } 1838 1839 void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) { 1840 for (int pr = 0; pr < _priority_max; ++pr) { 1841 _priority_buffer[pr]->flush_stats_and_retire(stats, end_of_gc, retain); 1842 } 1843 } 1844 1845 void update(bool end_of_gc, bool retain, HeapWord* buf, size_t word_sz) { 1846 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0]; 1847 retired_and_set->retire(end_of_gc, retain); 1848 retired_and_set->set_buf(buf); 1849 retired_and_set->set_word_size(word_sz); 1850 adjust_priority_order(); 1851 } 1852 1853 private: 1854 void adjust_priority_order() { 1855 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0]; 1856 1857 int last = _priority_max - 1; 1858 for (int pr = 0; pr < last; ++pr) { 1859 _priority_buffer[pr] = _priority_buffer[pr + 1]; 1860 } 1861 _priority_buffer[last] = retired_and_set; 1862 } 1863 }; 1864 1865 class G1ParScanThreadState : public StackObj { 1866 protected: 1867 G1CollectedHeap* _g1h; 1868 RefToScanQueue* _refs; 1869 DirtyCardQueue _dcq; 1870 G1SATBCardTableModRefBS* _ct_bs; 1871 G1RemSet* _g1_rem; 1872 1873 G1ParGCAllocBufferContainer _surviving_alloc_buffer; 1874 G1ParGCAllocBufferContainer _tenured_alloc_buffer; 1875 G1ParGCAllocBufferContainer* _alloc_buffers[GCAllocPurposeCount]; 1876 ageTable _age_table; 1877 1878 size_t _alloc_buffer_waste; 1879 size_t _undo_waste; 1880 1881 OopsInHeapRegionClosure* _evac_failure_cl; 1882 G1ParScanHeapEvacClosure* _evac_cl; 1883 G1ParScanPartialArrayClosure* _partial_scan_cl; 1884 1885 int _hash_seed; 1886 uint _queue_num; 1887 1888 size_t _term_attempts; 1889 1890 double _start; 1891 double _start_strong_roots; 1892 double _strong_roots_time; 1893 double _start_term; 1894 double _term_time; 1895 1896 // Map from young-age-index (0 == not young, 1 is youngest) to 1897 // surviving words. base is what we get back from the malloc call 1898 size_t* _surviving_young_words_base; 1899 // this points into the array, as we use the first few entries for padding 1900 size_t* _surviving_young_words; 1901 1902 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1903 1904 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1905 1906 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1907 1908 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1909 G1SATBCardTableModRefBS* ctbs() { return _ct_bs; } 1910 1911 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1912 if (!from->is_survivor()) { 1913 _g1_rem->par_write_ref(from, p, tid); 1914 } 1915 } 1916 1917 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1918 // If the new value of the field points to the same region or 1919 // is the to-space, we don't need to include it in the Rset updates. 1920 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1921 size_t card_index = ctbs()->index_for(p); 1922 // If the card hasn't been added to the buffer, do it. 1923 if (ctbs()->mark_card_deferred(card_index)) { 1924 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1925 } 1926 } 1927 } 1928 1929 public: 1930 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num); 1931 1932 ~G1ParScanThreadState() { 1933 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1934 } 1935 1936 RefToScanQueue* refs() { return _refs; } 1937 ageTable* age_table() { return &_age_table; } 1938 1939 G1ParGCAllocBufferContainer* alloc_buffer(GCAllocPurpose purpose) { 1940 return _alloc_buffers[purpose]; 1941 } 1942 1943 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1944 size_t undo_waste() const { return _undo_waste; } 1945 1946 #ifdef ASSERT 1947 bool verify_ref(narrowOop* ref) const; 1948 bool verify_ref(oop* ref) const; 1949 bool verify_task(StarTask ref) const; 1950 #endif // ASSERT 1951 1952 template <class T> void push_on_queue(T* ref) { 1953 assert(verify_ref(ref), "sanity"); 1954 refs()->push(ref); 1955 } 1956 1957 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1958 if (G1DeferredRSUpdate) { 1959 deferred_rs_update(from, p, tid); 1960 } else { 1961 immediate_rs_update(from, p, tid); 1962 } 1963 } 1964 1965 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1966 HeapWord* obj = NULL; 1967 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1968 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1969 G1ParGCAllocBufferContainer* alloc_buf = alloc_buffer(purpose); 1970 1971 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1972 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1973 1974 add_to_alloc_buffer_waste(alloc_buf->words_remaining_in_retired_buffer()); 1975 alloc_buf->update(false /* end_of_gc */, false /* retain */, buf, gclab_word_size); 1976 1977 obj = alloc_buf->allocate(word_sz); 1978 assert(obj != NULL, "buffer was definitely big enough..."); 1979 } else { 1980 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1981 } 1982 return obj; 1983 } 1984 1985 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1986 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1987 if (obj != NULL) return obj; 1988 return allocate_slow(purpose, word_sz); 1989 } 1990 1991 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1992 if (alloc_buffer(purpose)->contains(obj)) { 1993 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 1994 "should contain whole object"); 1995 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 1996 } else { 1997 CollectedHeap::fill_with_object(obj, word_sz); 1998 add_to_undo_waste(word_sz); 1999 } 2000 } 2001 2002 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 2003 _evac_failure_cl = evac_failure_cl; 2004 } 2005 OopsInHeapRegionClosure* evac_failure_closure() { 2006 return _evac_failure_cl; 2007 } 2008 2009 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 2010 _evac_cl = evac_cl; 2011 } 2012 2013 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 2014 _partial_scan_cl = partial_scan_cl; 2015 } 2016 2017 int* hash_seed() { return &_hash_seed; } 2018 uint queue_num() { return _queue_num; } 2019 2020 size_t term_attempts() const { return _term_attempts; } 2021 void note_term_attempt() { _term_attempts++; } 2022 2023 void start_strong_roots() { 2024 _start_strong_roots = os::elapsedTime(); 2025 } 2026 void end_strong_roots() { 2027 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 2028 } 2029 double strong_roots_time() const { return _strong_roots_time; } 2030 2031 void start_term_time() { 2032 note_term_attempt(); 2033 _start_term = os::elapsedTime(); 2034 } 2035 void end_term_time() { 2036 _term_time += (os::elapsedTime() - _start_term); 2037 } 2038 double term_time() const { return _term_time; } 2039 2040 double elapsed_time() const { 2041 return os::elapsedTime() - _start; 2042 } 2043 2044 static void 2045 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 2046 void 2047 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 2048 2049 size_t* surviving_young_words() { 2050 // We add on to hide entry 0 which accumulates surviving words for 2051 // age -1 regions (i.e. non-young ones) 2052 return _surviving_young_words; 2053 } 2054 2055 void retire_alloc_buffers() { 2056 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 2057 size_t waste = _alloc_buffers[ap]->words_remaining(); 2058 add_to_alloc_buffer_waste(waste); 2059 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 2060 true /* end_of_gc */, 2061 false /* retain */); 2062 } 2063 } 2064 2065 template <class T> void deal_with_reference(T* ref_to_scan) { 2066 if (has_partial_array_mask(ref_to_scan)) { 2067 _partial_scan_cl->do_oop_nv(ref_to_scan); 2068 } else { 2069 // Note: we can use "raw" versions of "region_containing" because 2070 // "obj_to_scan" is definitely in the heap, and is not in a 2071 // humongous region. 2072 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 2073 _evac_cl->set_region(r); 2074 _evac_cl->do_oop_nv(ref_to_scan); 2075 } 2076 } 2077 2078 void deal_with_reference(StarTask ref) { 2079 assert(verify_task(ref), "sanity"); 2080 if (ref.is_narrow()) { 2081 deal_with_reference((narrowOop*)ref); 2082 } else { 2083 deal_with_reference((oop*)ref); 2084 } 2085 } 2086 2087 void trim_queue(); 2088 }; 2089 2090 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP