1 /* 2 * Copyright (c) 2001, 2011, 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/g1AllocRegion.hpp" 30 #include "gc_implementation/g1/g1HRPrinter.hpp" 31 #include "gc_implementation/g1/g1RemSet.hpp" 32 #include "gc_implementation/g1/g1MonitoringSupport.hpp" 33 #include "gc_implementation/g1/heapRegionSeq.hpp" 34 #include "gc_implementation/g1/heapRegionSets.hpp" 35 #include "gc_implementation/shared/hSpaceCounters.hpp" 36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp" 37 #include "memory/barrierSet.hpp" 38 #include "memory/memRegion.hpp" 39 #include "memory/sharedHeap.hpp" 40 41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 42 // It uses the "Garbage First" heap organization and algorithm, which 43 // may combine concurrent marking with parallel, incremental compaction of 44 // heap subsets that will yield large amounts of garbage. 45 46 class HeapRegion; 47 class HRRSCleanupTask; 48 class PermanentGenerationSpec; 49 class GenerationSpec; 50 class OopsInHeapRegionClosure; 51 class G1ScanHeapEvacClosure; 52 class ObjectClosure; 53 class SpaceClosure; 54 class CompactibleSpaceClosure; 55 class Space; 56 class G1CollectorPolicy; 57 class GenRemSet; 58 class G1RemSet; 59 class HeapRegionRemSetIterator; 60 class ConcurrentMark; 61 class ConcurrentMarkThread; 62 class ConcurrentG1Refine; 63 class GenerationCounters; 64 65 typedef OverflowTaskQueue<StarTask> RefToScanQueue; 66 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet; 67 68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 70 71 enum GCAllocPurpose { 72 GCAllocForTenured, 73 GCAllocForSurvived, 74 GCAllocPurposeCount 75 }; 76 77 class YoungList : public CHeapObj { 78 private: 79 G1CollectedHeap* _g1h; 80 81 HeapRegion* _head; 82 83 HeapRegion* _survivor_head; 84 HeapRegion* _survivor_tail; 85 86 HeapRegion* _curr; 87 88 size_t _length; 89 size_t _survivor_length; 90 91 size_t _last_sampled_rs_lengths; 92 size_t _sampled_rs_lengths; 93 94 void empty_list(HeapRegion* list); 95 96 public: 97 YoungList(G1CollectedHeap* g1h); 98 99 void push_region(HeapRegion* hr); 100 void add_survivor_region(HeapRegion* hr); 101 102 void empty_list(); 103 bool is_empty() { return _length == 0; } 104 size_t length() { return _length; } 105 size_t survivor_length() { return _survivor_length; } 106 107 // Currently we do not keep track of the used byte sum for the 108 // young list and the survivors and it'd be quite a lot of work to 109 // do so. When we'll eventually replace the young list with 110 // instances of HeapRegionLinkedList we'll get that for free. So, 111 // we'll report the more accurate information then. 112 size_t eden_used_bytes() { 113 assert(length() >= survivor_length(), "invariant"); 114 return (length() - survivor_length()) * HeapRegion::GrainBytes; 115 } 116 size_t survivor_used_bytes() { 117 return survivor_length() * HeapRegion::GrainBytes; 118 } 119 120 void rs_length_sampling_init(); 121 bool rs_length_sampling_more(); 122 void rs_length_sampling_next(); 123 124 void reset_sampled_info() { 125 _last_sampled_rs_lengths = 0; 126 } 127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 128 129 // for development purposes 130 void reset_auxilary_lists(); 131 void clear() { _head = NULL; _length = 0; } 132 133 void clear_survivors() { 134 _survivor_head = NULL; 135 _survivor_tail = NULL; 136 _survivor_length = 0; 137 } 138 139 HeapRegion* first_region() { return _head; } 140 HeapRegion* first_survivor_region() { return _survivor_head; } 141 HeapRegion* last_survivor_region() { return _survivor_tail; } 142 143 // debugging 144 bool check_list_well_formed(); 145 bool check_list_empty(bool check_sample = true); 146 void print(); 147 }; 148 149 class MutatorAllocRegion : public G1AllocRegion { 150 protected: 151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 153 public: 154 MutatorAllocRegion() 155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 156 }; 157 158 class SurvivorGCAllocRegion : public G1AllocRegion { 159 protected: 160 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 161 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 162 public: 163 SurvivorGCAllocRegion() 164 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { } 165 }; 166 167 class OldGCAllocRegion : public G1AllocRegion { 168 protected: 169 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 170 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 171 public: 172 OldGCAllocRegion() 173 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { } 174 }; 175 176 class RefineCardTableEntryClosure; 177 class G1CollectedHeap : public SharedHeap { 178 friend class VM_G1CollectForAllocation; 179 friend class VM_GenCollectForPermanentAllocation; 180 friend class VM_G1CollectFull; 181 friend class VM_G1IncCollectionPause; 182 friend class VMStructs; 183 friend class MutatorAllocRegion; 184 friend class SurvivorGCAllocRegion; 185 friend class OldGCAllocRegion; 186 187 // Closures used in implementation. 188 friend class G1ParCopyHelper; 189 friend class G1IsAliveClosure; 190 friend class G1EvacuateFollowersClosure; 191 friend class G1ParScanThreadState; 192 friend class G1ParScanClosureSuper; 193 friend class G1ParEvacuateFollowersClosure; 194 friend class G1ParTask; 195 friend class G1FreeGarbageRegionClosure; 196 friend class RefineCardTableEntryClosure; 197 friend class G1PrepareCompactClosure; 198 friend class RegionSorter; 199 friend class RegionResetter; 200 friend class CountRCClosure; 201 friend class EvacPopObjClosure; 202 friend class G1ParCleanupCTTask; 203 204 // Other related classes. 205 friend class G1MarkSweep; 206 207 private: 208 // The one and only G1CollectedHeap, so static functions can find it. 209 static G1CollectedHeap* _g1h; 210 211 static size_t _humongous_object_threshold_in_words; 212 213 // Storage for the G1 heap (excludes the permanent generation). 214 VirtualSpace _g1_storage; 215 MemRegion _g1_reserved; 216 217 // The part of _g1_storage that is currently committed. 218 MemRegion _g1_committed; 219 220 // The master free list. It will satisfy all new region allocations. 221 MasterFreeRegionList _free_list; 222 223 // The secondary free list which contains regions that have been 224 // freed up during the cleanup process. This will be appended to the 225 // master free list when appropriate. 226 SecondaryFreeRegionList _secondary_free_list; 227 228 // It keeps track of the humongous regions. 229 MasterHumongousRegionSet _humongous_set; 230 231 // The number of regions we could create by expansion. 232 size_t _expansion_regions; 233 234 // The block offset table for the G1 heap. 235 G1BlockOffsetSharedArray* _bot_shared; 236 237 // Move all of the regions off the free lists, then rebuild those free 238 // lists, before and after full GC. 239 void tear_down_region_lists(); 240 void rebuild_region_lists(); 241 242 // The sequence of all heap regions in the heap. 243 HeapRegionSeq _hrs; 244 245 // Alloc region used to satisfy mutator allocation requests. 246 MutatorAllocRegion _mutator_alloc_region; 247 248 // Alloc region used to satisfy allocation requests by the GC for 249 // survivor objects. 250 SurvivorGCAllocRegion _survivor_gc_alloc_region; 251 252 // Alloc region used to satisfy allocation requests by the GC for 253 // old objects. 254 OldGCAllocRegion _old_gc_alloc_region; 255 256 // The last old region we allocated to during the last GC. 257 // Typically, it is not full so we should re-use it during the next GC. 258 HeapRegion* _retained_old_gc_alloc_region; 259 260 // It resets the mutator alloc region before new allocations can take place. 261 void init_mutator_alloc_region(); 262 263 // It releases the mutator alloc region. 264 void release_mutator_alloc_region(); 265 266 // It initializes the GC alloc regions at the start of a GC. 267 void init_gc_alloc_regions(); 268 269 // It releases the GC alloc regions at the end of a GC. 270 void release_gc_alloc_regions(); 271 272 // It does any cleanup that needs to be done on the GC alloc regions 273 // before a Full GC. 274 void abandon_gc_alloc_regions(); 275 276 // Helper for monitoring and management support. 277 G1MonitoringSupport* _g1mm; 278 279 // Determines PLAB size for a particular allocation purpose. 280 static size_t desired_plab_sz(GCAllocPurpose purpose); 281 282 // Outside of GC pauses, the number of bytes used in all regions other 283 // than the current allocation region. 284 size_t _summary_bytes_used; 285 286 // This is used for a quick test on whether a reference points into 287 // the collection set or not. Basically, we have an array, with one 288 // byte per region, and that byte denotes whether the corresponding 289 // region is in the collection set or not. The entry corresponding 290 // the bottom of the heap, i.e., region 0, is pointed to by 291 // _in_cset_fast_test_base. The _in_cset_fast_test field has been 292 // biased so that it actually points to address 0 of the address 293 // space, to make the test as fast as possible (we can simply shift 294 // the address to address into it, instead of having to subtract the 295 // bottom of the heap from the address before shifting it; basically 296 // it works in the same way the card table works). 297 bool* _in_cset_fast_test; 298 299 // The allocated array used for the fast test on whether a reference 300 // points into the collection set or not. This field is also used to 301 // free the array. 302 bool* _in_cset_fast_test_base; 303 304 // The length of the _in_cset_fast_test_base array. 305 size_t _in_cset_fast_test_length; 306 307 volatile unsigned _gc_time_stamp; 308 309 size_t* _surviving_young_words; 310 311 G1HRPrinter _hr_printer; 312 313 void setup_surviving_young_words(); 314 void update_surviving_young_words(size_t* surv_young_words); 315 void cleanup_surviving_young_words(); 316 317 // It decides whether an explicit GC should start a concurrent cycle 318 // instead of doing a STW GC. Currently, a concurrent cycle is 319 // explicitly started if: 320 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 321 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 322 bool should_do_concurrent_full_gc(GCCause::Cause cause); 323 324 // Keeps track of how many "full collections" (i.e., Full GCs or 325 // concurrent cycles) we have completed. The number of them we have 326 // started is maintained in _total_full_collections in CollectedHeap. 327 volatile unsigned int _full_collections_completed; 328 329 // This is a non-product method that is helpful for testing. It is 330 // called at the end of a GC and artificially expands the heap by 331 // allocating a number of dead regions. This way we can induce very 332 // frequent marking cycles and stress the cleanup / concurrent 333 // cleanup code more (as all the regions that will be allocated by 334 // this method will be found dead by the marking cycle). 335 void allocate_dummy_regions() PRODUCT_RETURN; 336 337 // These are macros so that, if the assert fires, we get the correct 338 // line number, file, etc. 339 340 #define heap_locking_asserts_err_msg(_extra_message_) \ 341 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 342 (_extra_message_), \ 343 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 344 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 345 BOOL_TO_STR(Thread::current()->is_VM_thread())) 346 347 #define assert_heap_locked() \ 348 do { \ 349 assert(Heap_lock->owned_by_self(), \ 350 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 351 } while (0) 352 353 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 354 do { \ 355 assert(Heap_lock->owned_by_self() || \ 356 (SafepointSynchronize::is_at_safepoint() && \ 357 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 358 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 359 "should be at a safepoint")); \ 360 } while (0) 361 362 #define assert_heap_locked_and_not_at_safepoint() \ 363 do { \ 364 assert(Heap_lock->owned_by_self() && \ 365 !SafepointSynchronize::is_at_safepoint(), \ 366 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 367 "should not be at a safepoint")); \ 368 } while (0) 369 370 #define assert_heap_not_locked() \ 371 do { \ 372 assert(!Heap_lock->owned_by_self(), \ 373 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 374 } while (0) 375 376 #define assert_heap_not_locked_and_not_at_safepoint() \ 377 do { \ 378 assert(!Heap_lock->owned_by_self() && \ 379 !SafepointSynchronize::is_at_safepoint(), \ 380 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 381 "should not be at a safepoint")); \ 382 } while (0) 383 384 #define assert_at_safepoint(_should_be_vm_thread_) \ 385 do { \ 386 assert(SafepointSynchronize::is_at_safepoint() && \ 387 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 388 heap_locking_asserts_err_msg("should be at a safepoint")); \ 389 } while (0) 390 391 #define assert_not_at_safepoint() \ 392 do { \ 393 assert(!SafepointSynchronize::is_at_safepoint(), \ 394 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 395 } while (0) 396 397 protected: 398 399 // The young region list. 400 YoungList* _young_list; 401 402 // The current policy object for the collector. 403 G1CollectorPolicy* _g1_policy; 404 405 // This is the second level of trying to allocate a new region. If 406 // new_region() didn't find a region on the free_list, this call will 407 // check whether there's anything available on the 408 // secondary_free_list and/or wait for more regions to appear on 409 // that list, if _free_regions_coming is set. 410 HeapRegion* new_region_try_secondary_free_list(); 411 412 // Try to allocate a single non-humongous HeapRegion sufficient for 413 // an allocation of the given word_size. If do_expand is true, 414 // attempt to expand the heap if necessary to satisfy the allocation 415 // request. 416 HeapRegion* new_region(size_t word_size, bool do_expand); 417 418 // Attempt to satisfy a humongous allocation request of the given 419 // size by finding a contiguous set of free regions of num_regions 420 // length and remove them from the master free list. Return the 421 // index of the first region or G1_NULL_HRS_INDEX if the search 422 // was unsuccessful. 423 size_t humongous_obj_allocate_find_first(size_t num_regions, 424 size_t word_size); 425 426 // Initialize a contiguous set of free regions of length num_regions 427 // and starting at index first so that they appear as a single 428 // humongous region. 429 HeapWord* humongous_obj_allocate_initialize_regions(size_t first, 430 size_t num_regions, 431 size_t word_size); 432 433 // Attempt to allocate a humongous object of the given size. Return 434 // NULL if unsuccessful. 435 HeapWord* humongous_obj_allocate(size_t word_size); 436 437 // The following two methods, allocate_new_tlab() and 438 // mem_allocate(), are the two main entry points from the runtime 439 // into the G1's allocation routines. They have the following 440 // assumptions: 441 // 442 // * They should both be called outside safepoints. 443 // 444 // * They should both be called without holding the Heap_lock. 445 // 446 // * All allocation requests for new TLABs should go to 447 // allocate_new_tlab(). 448 // 449 // * All non-TLAB allocation requests should go to mem_allocate(). 450 // 451 // * If either call cannot satisfy the allocation request using the 452 // current allocating region, they will try to get a new one. If 453 // this fails, they will attempt to do an evacuation pause and 454 // retry the allocation. 455 // 456 // * If all allocation attempts fail, even after trying to schedule 457 // an evacuation pause, allocate_new_tlab() will return NULL, 458 // whereas mem_allocate() will attempt a heap expansion and/or 459 // schedule a Full GC. 460 // 461 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 462 // should never be called with word_size being humongous. All 463 // humongous allocation requests should go to mem_allocate() which 464 // will satisfy them with a special path. 465 466 virtual HeapWord* allocate_new_tlab(size_t word_size); 467 468 virtual HeapWord* mem_allocate(size_t word_size, 469 bool* gc_overhead_limit_was_exceeded); 470 471 // The following three methods take a gc_count_before_ret 472 // parameter which is used to return the GC count if the method 473 // returns NULL. Given that we are required to read the GC count 474 // while holding the Heap_lock, and these paths will take the 475 // Heap_lock at some point, it's easier to get them to read the GC 476 // count while holding the Heap_lock before they return NULL instead 477 // of the caller (namely: mem_allocate()) having to also take the 478 // Heap_lock just to read the GC count. 479 480 // First-level mutator allocation attempt: try to allocate out of 481 // the mutator alloc region without taking the Heap_lock. This 482 // should only be used for non-humongous allocations. 483 inline HeapWord* attempt_allocation(size_t word_size, 484 unsigned int* gc_count_before_ret); 485 486 // Second-level mutator allocation attempt: take the Heap_lock and 487 // retry the allocation attempt, potentially scheduling a GC 488 // pause. This should only be used for non-humongous allocations. 489 HeapWord* attempt_allocation_slow(size_t word_size, 490 unsigned int* gc_count_before_ret); 491 492 // Takes the Heap_lock and attempts a humongous allocation. It can 493 // potentially schedule a GC pause. 494 HeapWord* attempt_allocation_humongous(size_t word_size, 495 unsigned int* gc_count_before_ret); 496 497 // Allocation attempt that should be called during safepoints (e.g., 498 // at the end of a successful GC). expect_null_mutator_alloc_region 499 // specifies whether the mutator alloc region is expected to be NULL 500 // or not. 501 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 502 bool expect_null_mutator_alloc_region); 503 504 // It dirties the cards that cover the block so that so that the post 505 // write barrier never queues anything when updating objects on this 506 // block. It is assumed (and in fact we assert) that the block 507 // belongs to a young region. 508 inline void dirty_young_block(HeapWord* start, size_t word_size); 509 510 // Allocate blocks during garbage collection. Will ensure an 511 // allocation region, either by picking one or expanding the 512 // heap, and then allocate a block of the given size. The block 513 // may not be a humongous - it must fit into a single heap region. 514 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 515 516 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 517 HeapRegion* alloc_region, 518 bool par, 519 size_t word_size); 520 521 // Ensure that no further allocations can happen in "r", bearing in mind 522 // that parallel threads might be attempting allocations. 523 void par_allocate_remaining_space(HeapRegion* r); 524 525 // Allocation attempt during GC for a survivor object / PLAB. 526 inline HeapWord* survivor_attempt_allocation(size_t word_size); 527 528 // Allocation attempt during GC for an old object / PLAB. 529 inline HeapWord* old_attempt_allocation(size_t word_size); 530 531 // These methods are the "callbacks" from the G1AllocRegion class. 532 533 // For mutator alloc regions. 534 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 535 void retire_mutator_alloc_region(HeapRegion* alloc_region, 536 size_t allocated_bytes); 537 538 // For GC alloc regions. 539 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count, 540 GCAllocPurpose ap); 541 void retire_gc_alloc_region(HeapRegion* alloc_region, 542 size_t allocated_bytes, GCAllocPurpose ap); 543 544 // - if explicit_gc is true, the GC is for a System.gc() or a heap 545 // inspection request and should collect the entire heap 546 // - if clear_all_soft_refs is true, all soft references should be 547 // cleared during the GC 548 // - if explicit_gc is false, word_size describes the allocation that 549 // the GC should attempt (at least) to satisfy 550 // - it returns false if it is unable to do the collection due to the 551 // GC locker being active, true otherwise 552 bool do_collection(bool explicit_gc, 553 bool clear_all_soft_refs, 554 size_t word_size); 555 556 // Callback from VM_G1CollectFull operation. 557 // Perform a full collection. 558 void do_full_collection(bool clear_all_soft_refs); 559 560 // Resize the heap if necessary after a full collection. If this is 561 // after a collect-for allocation, "word_size" is the allocation size, 562 // and will be considered part of the used portion of the heap. 563 void resize_if_necessary_after_full_collection(size_t word_size); 564 565 // Callback from VM_G1CollectForAllocation operation. 566 // This function does everything necessary/possible to satisfy a 567 // failed allocation request (including collection, expansion, etc.) 568 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 569 570 // Attempting to expand the heap sufficiently 571 // to support an allocation of the given "word_size". If 572 // successful, perform the allocation and return the address of the 573 // allocated block, or else "NULL". 574 HeapWord* expand_and_allocate(size_t word_size); 575 576 public: 577 578 G1MonitoringSupport* g1mm() { return _g1mm; } 579 580 // Expand the garbage-first heap by at least the given size (in bytes!). 581 // Returns true if the heap was expanded by the requested amount; 582 // false otherwise. 583 // (Rounds up to a HeapRegion boundary.) 584 bool expand(size_t expand_bytes); 585 586 // Do anything common to GC's. 587 virtual void gc_prologue(bool full); 588 virtual void gc_epilogue(bool full); 589 590 // We register a region with the fast "in collection set" test. We 591 // simply set to true the array slot corresponding to this region. 592 void register_region_with_in_cset_fast_test(HeapRegion* r) { 593 assert(_in_cset_fast_test_base != NULL, "sanity"); 594 assert(r->in_collection_set(), "invariant"); 595 size_t index = r->hrs_index(); 596 assert(index < _in_cset_fast_test_length, "invariant"); 597 assert(!_in_cset_fast_test_base[index], "invariant"); 598 _in_cset_fast_test_base[index] = true; 599 } 600 601 // This is a fast test on whether a reference points into the 602 // collection set or not. It does not assume that the reference 603 // points into the heap; if it doesn't, it will return false. 604 bool in_cset_fast_test(oop obj) { 605 assert(_in_cset_fast_test != NULL, "sanity"); 606 if (_g1_committed.contains((HeapWord*) obj)) { 607 // no need to subtract the bottom of the heap from obj, 608 // _in_cset_fast_test is biased 609 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes; 610 bool ret = _in_cset_fast_test[index]; 611 // let's make sure the result is consistent with what the slower 612 // test returns 613 assert( ret || !obj_in_cs(obj), "sanity"); 614 assert(!ret || obj_in_cs(obj), "sanity"); 615 return ret; 616 } else { 617 return false; 618 } 619 } 620 621 void clear_cset_fast_test() { 622 assert(_in_cset_fast_test_base != NULL, "sanity"); 623 memset(_in_cset_fast_test_base, false, 624 _in_cset_fast_test_length * sizeof(bool)); 625 } 626 627 // This is called at the end of either a concurrent cycle or a Full 628 // GC to update the number of full collections completed. Those two 629 // can happen in a nested fashion, i.e., we start a concurrent 630 // cycle, a Full GC happens half-way through it which ends first, 631 // and then the cycle notices that a Full GC happened and ends 632 // too. The concurrent parameter is a boolean to help us do a bit 633 // tighter consistency checking in the method. If concurrent is 634 // false, the caller is the inner caller in the nesting (i.e., the 635 // Full GC). If concurrent is true, the caller is the outer caller 636 // in this nesting (i.e., the concurrent cycle). Further nesting is 637 // not currently supported. The end of the this call also notifies 638 // the FullGCCount_lock in case a Java thread is waiting for a full 639 // GC to happen (e.g., it called System.gc() with 640 // +ExplicitGCInvokesConcurrent). 641 void increment_full_collections_completed(bool concurrent); 642 643 unsigned int full_collections_completed() { 644 return _full_collections_completed; 645 } 646 647 G1HRPrinter* hr_printer() { return &_hr_printer; } 648 649 protected: 650 651 // Shrink the garbage-first heap by at most the given size (in bytes!). 652 // (Rounds down to a HeapRegion boundary.) 653 virtual void shrink(size_t expand_bytes); 654 void shrink_helper(size_t expand_bytes); 655 656 #if TASKQUEUE_STATS 657 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 658 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 659 void reset_taskqueue_stats(); 660 #endif // TASKQUEUE_STATS 661 662 // Schedule the VM operation that will do an evacuation pause to 663 // satisfy an allocation request of word_size. *succeeded will 664 // return whether the VM operation was successful (it did do an 665 // evacuation pause) or not (another thread beat us to it or the GC 666 // locker was active). Given that we should not be holding the 667 // Heap_lock when we enter this method, we will pass the 668 // gc_count_before (i.e., total_collections()) as a parameter since 669 // it has to be read while holding the Heap_lock. Currently, both 670 // methods that call do_collection_pause() release the Heap_lock 671 // before the call, so it's easy to read gc_count_before just before. 672 HeapWord* do_collection_pause(size_t word_size, 673 unsigned int gc_count_before, 674 bool* succeeded); 675 676 // The guts of the incremental collection pause, executed by the vm 677 // thread. It returns false if it is unable to do the collection due 678 // to the GC locker being active, true otherwise 679 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 680 681 // Actually do the work of evacuating the collection set. 682 void evacuate_collection_set(); 683 684 // The g1 remembered set of the heap. 685 G1RemSet* _g1_rem_set; 686 // And it's mod ref barrier set, used to track updates for the above. 687 ModRefBarrierSet* _mr_bs; 688 689 // A set of cards that cover the objects for which the Rsets should be updated 690 // concurrently after the collection. 691 DirtyCardQueueSet _dirty_card_queue_set; 692 693 // The Heap Region Rem Set Iterator. 694 HeapRegionRemSetIterator** _rem_set_iterator; 695 696 // The closure used to refine a single card. 697 RefineCardTableEntryClosure* _refine_cte_cl; 698 699 // A function to check the consistency of dirty card logs. 700 void check_ct_logs_at_safepoint(); 701 702 // A DirtyCardQueueSet that is used to hold cards that contain 703 // references into the current collection set. This is used to 704 // update the remembered sets of the regions in the collection 705 // set in the event of an evacuation failure. 706 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 707 708 // After a collection pause, make the regions in the CS into free 709 // regions. 710 void free_collection_set(HeapRegion* cs_head); 711 712 // Abandon the current collection set without recording policy 713 // statistics or updating free lists. 714 void abandon_collection_set(HeapRegion* cs_head); 715 716 // Applies "scan_non_heap_roots" to roots outside the heap, 717 // "scan_rs" to roots inside the heap (having done "set_region" to 718 // indicate the region in which the root resides), and does "scan_perm" 719 // (setting the generation to the perm generation.) If "scan_rs" is 720 // NULL, then this step is skipped. The "worker_i" 721 // param is for use with parallel roots processing, and should be 722 // the "i" of the calling parallel worker thread's work(i) function. 723 // In the sequential case this param will be ignored. 724 void g1_process_strong_roots(bool collecting_perm_gen, 725 SharedHeap::ScanningOption so, 726 OopClosure* scan_non_heap_roots, 727 OopsInHeapRegionClosure* scan_rs, 728 OopsInGenClosure* scan_perm, 729 int worker_i); 730 731 // Apply "blk" to all the weak roots of the system. These include 732 // JNI weak roots, the code cache, system dictionary, symbol table, 733 // string table, and referents of reachable weak refs. 734 void g1_process_weak_roots(OopClosure* root_closure, 735 OopClosure* non_root_closure); 736 737 // Frees a non-humongous region by initializing its contents and 738 // adding it to the free list that's passed as a parameter (this is 739 // usually a local list which will be appended to the master free 740 // list later). The used bytes of freed regions are accumulated in 741 // pre_used. If par is true, the region's RSet will not be freed 742 // up. The assumption is that this will be done later. 743 void free_region(HeapRegion* hr, 744 size_t* pre_used, 745 FreeRegionList* free_list, 746 bool par); 747 748 // Frees a humongous region by collapsing it into individual regions 749 // and calling free_region() for each of them. The freed regions 750 // will be added to the free list that's passed as a parameter (this 751 // is usually a local list which will be appended to the master free 752 // list later). The used bytes of freed regions are accumulated in 753 // pre_used. If par is true, the region's RSet will not be freed 754 // up. The assumption is that this will be done later. 755 void free_humongous_region(HeapRegion* hr, 756 size_t* pre_used, 757 FreeRegionList* free_list, 758 HumongousRegionSet* humongous_proxy_set, 759 bool par); 760 761 // Notifies all the necessary spaces that the committed space has 762 // been updated (either expanded or shrunk). It should be called 763 // after _g1_storage is updated. 764 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 765 766 // The concurrent marker (and the thread it runs in.) 767 ConcurrentMark* _cm; 768 ConcurrentMarkThread* _cmThread; 769 bool _mark_in_progress; 770 771 // The concurrent refiner. 772 ConcurrentG1Refine* _cg1r; 773 774 // The parallel task queues 775 RefToScanQueueSet *_task_queues; 776 777 // True iff a evacuation has failed in the current collection. 778 bool _evacuation_failed; 779 780 // Set the attribute indicating whether evacuation has failed in the 781 // current collection. 782 void set_evacuation_failed(bool b) { _evacuation_failed = b; } 783 784 // Failed evacuations cause some logical from-space objects to have 785 // forwarding pointers to themselves. Reset them. 786 void remove_self_forwarding_pointers(); 787 788 // When one is non-null, so is the other. Together, they each pair is 789 // an object with a preserved mark, and its mark value. 790 GrowableArray<oop>* _objs_with_preserved_marks; 791 GrowableArray<markOop>* _preserved_marks_of_objs; 792 793 // Preserve the mark of "obj", if necessary, in preparation for its mark 794 // word being overwritten with a self-forwarding-pointer. 795 void preserve_mark_if_necessary(oop obj, markOop m); 796 797 // The stack of evac-failure objects left to be scanned. 798 GrowableArray<oop>* _evac_failure_scan_stack; 799 // The closure to apply to evac-failure objects. 800 801 OopsInHeapRegionClosure* _evac_failure_closure; 802 // Set the field above. 803 void 804 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 805 _evac_failure_closure = evac_failure_closure; 806 } 807 808 // Push "obj" on the scan stack. 809 void push_on_evac_failure_scan_stack(oop obj); 810 // Process scan stack entries until the stack is empty. 811 void drain_evac_failure_scan_stack(); 812 // True iff an invocation of "drain_scan_stack" is in progress; to 813 // prevent unnecessary recursion. 814 bool _drain_in_progress; 815 816 // Do any necessary initialization for evacuation-failure handling. 817 // "cl" is the closure that will be used to process evac-failure 818 // objects. 819 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 820 // Do any necessary cleanup for evacuation-failure handling data 821 // structures. 822 void finalize_for_evac_failure(); 823 824 // An attempt to evacuate "obj" has failed; take necessary steps. 825 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj); 826 void handle_evacuation_failure_common(oop obj, markOop m); 827 828 // Instance of the concurrent mark is_alive closure for embedding 829 // into the reference processor as the is_alive_non_header. This 830 // prevents unnecessary additions to the discovered lists during 831 // concurrent discovery. 832 G1CMIsAliveClosure _is_alive_closure; 833 834 // ("Weak") Reference processing support 835 ReferenceProcessor* _ref_processor; 836 837 enum G1H_process_strong_roots_tasks { 838 G1H_PS_mark_stack_oops_do, 839 G1H_PS_refProcessor_oops_do, 840 // Leave this one last. 841 G1H_PS_NumElements 842 }; 843 844 SubTasksDone* _process_strong_tasks; 845 846 volatile bool _free_regions_coming; 847 848 public: 849 850 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 851 852 void set_refine_cte_cl_concurrency(bool concurrent); 853 854 RefToScanQueue *task_queue(int i) const; 855 856 // A set of cards where updates happened during the GC 857 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 858 859 // A DirtyCardQueueSet that is used to hold cards that contain 860 // references into the current collection set. This is used to 861 // update the remembered sets of the regions in the collection 862 // set in the event of an evacuation failure. 863 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 864 { return _into_cset_dirty_card_queue_set; } 865 866 // Create a G1CollectedHeap with the specified policy. 867 // Must call the initialize method afterwards. 868 // May not return if something goes wrong. 869 G1CollectedHeap(G1CollectorPolicy* policy); 870 871 // Initialize the G1CollectedHeap to have the initial and 872 // maximum sizes, permanent generation, and remembered and barrier sets 873 // specified by the policy object. 874 jint initialize(); 875 876 virtual void ref_processing_init(); 877 878 void set_par_threads(int t) { 879 SharedHeap::set_par_threads(t); 880 _process_strong_tasks->set_n_threads(t); 881 } 882 883 virtual CollectedHeap::Name kind() const { 884 return CollectedHeap::G1CollectedHeap; 885 } 886 887 // The current policy object for the collector. 888 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 889 890 // Adaptive size policy. No such thing for g1. 891 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 892 893 // The rem set and barrier set. 894 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 895 ModRefBarrierSet* mr_bs() const { return _mr_bs; } 896 897 // The rem set iterator. 898 HeapRegionRemSetIterator* rem_set_iterator(int i) { 899 return _rem_set_iterator[i]; 900 } 901 902 HeapRegionRemSetIterator* rem_set_iterator() { 903 return _rem_set_iterator[0]; 904 } 905 906 unsigned get_gc_time_stamp() { 907 return _gc_time_stamp; 908 } 909 910 void reset_gc_time_stamp() { 911 _gc_time_stamp = 0; 912 OrderAccess::fence(); 913 } 914 915 void increment_gc_time_stamp() { 916 ++_gc_time_stamp; 917 OrderAccess::fence(); 918 } 919 920 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 921 DirtyCardQueue* into_cset_dcq, 922 bool concurrent, int worker_i); 923 924 // The shared block offset table array. 925 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 926 927 // Reference Processing accessor 928 ReferenceProcessor* ref_processor() { return _ref_processor; } 929 930 virtual size_t capacity() const; 931 virtual size_t used() const; 932 // This should be called when we're not holding the heap lock. The 933 // result might be a bit inaccurate. 934 size_t used_unlocked() const; 935 size_t recalculate_used() const; 936 937 // These virtual functions do the actual allocation. 938 // Some heaps may offer a contiguous region for shared non-blocking 939 // allocation, via inlined code (by exporting the address of the top and 940 // end fields defining the extent of the contiguous allocation region.) 941 // But G1CollectedHeap doesn't yet support this. 942 943 // Return an estimate of the maximum allocation that could be performed 944 // without triggering any collection or expansion activity. In a 945 // generational collector, for example, this is probably the largest 946 // allocation that could be supported (without expansion) in the youngest 947 // generation. It is "unsafe" because no locks are taken; the result 948 // should be treated as an approximation, not a guarantee, for use in 949 // heuristic resizing decisions. 950 virtual size_t unsafe_max_alloc(); 951 952 virtual bool is_maximal_no_gc() const { 953 return _g1_storage.uncommitted_size() == 0; 954 } 955 956 // The total number of regions in the heap. 957 size_t n_regions() { return _hrs.length(); } 958 959 // The max number of regions in the heap. 960 size_t max_regions() { return _hrs.max_length(); } 961 962 // The number of regions that are completely free. 963 size_t free_regions() { return _free_list.length(); } 964 965 // The number of regions that are not completely free. 966 size_t used_regions() { return n_regions() - free_regions(); } 967 968 // The number of regions available for "regular" expansion. 969 size_t expansion_regions() { return _expansion_regions; } 970 971 // Factory method for HeapRegion instances. It will return NULL if 972 // the allocation fails. 973 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom); 974 975 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 976 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 977 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 978 void verify_dirty_young_regions() PRODUCT_RETURN; 979 980 // verify_region_sets() performs verification over the region 981 // lists. It will be compiled in the product code to be used when 982 // necessary (i.e., during heap verification). 983 void verify_region_sets(); 984 985 // verify_region_sets_optional() is planted in the code for 986 // list verification in non-product builds (and it can be enabled in 987 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1). 988 #if HEAP_REGION_SET_FORCE_VERIFY 989 void verify_region_sets_optional() { 990 verify_region_sets(); 991 } 992 #else // HEAP_REGION_SET_FORCE_VERIFY 993 void verify_region_sets_optional() { } 994 #endif // HEAP_REGION_SET_FORCE_VERIFY 995 996 #ifdef ASSERT 997 bool is_on_master_free_list(HeapRegion* hr) { 998 return hr->containing_set() == &_free_list; 999 } 1000 1001 bool is_in_humongous_set(HeapRegion* hr) { 1002 return hr->containing_set() == &_humongous_set; 1003 } 1004 #endif // ASSERT 1005 1006 // Wrapper for the region list operations that can be called from 1007 // methods outside this class. 1008 1009 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1010 _secondary_free_list.add_as_tail(list); 1011 } 1012 1013 void append_secondary_free_list() { 1014 _free_list.add_as_head(&_secondary_free_list); 1015 } 1016 1017 void append_secondary_free_list_if_not_empty_with_lock() { 1018 // If the secondary free list looks empty there's no reason to 1019 // take the lock and then try to append it. 1020 if (!_secondary_free_list.is_empty()) { 1021 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1022 append_secondary_free_list(); 1023 } 1024 } 1025 1026 void set_free_regions_coming(); 1027 void reset_free_regions_coming(); 1028 bool free_regions_coming() { return _free_regions_coming; } 1029 void wait_while_free_regions_coming(); 1030 1031 // Perform a collection of the heap; intended for use in implementing 1032 // "System.gc". This probably implies as full a collection as the 1033 // "CollectedHeap" supports. 1034 virtual void collect(GCCause::Cause cause); 1035 1036 // The same as above but assume that the caller holds the Heap_lock. 1037 void collect_locked(GCCause::Cause cause); 1038 1039 // This interface assumes that it's being called by the 1040 // vm thread. It collects the heap assuming that the 1041 // heap lock is already held and that we are executing in 1042 // the context of the vm thread. 1043 virtual void collect_as_vm_thread(GCCause::Cause cause); 1044 1045 // True iff a evacuation has failed in the most-recent collection. 1046 bool evacuation_failed() { return _evacuation_failed; } 1047 1048 // It will free a region if it has allocated objects in it that are 1049 // all dead. It calls either free_region() or 1050 // free_humongous_region() depending on the type of the region that 1051 // is passed to it. 1052 void free_region_if_empty(HeapRegion* hr, 1053 size_t* pre_used, 1054 FreeRegionList* free_list, 1055 HumongousRegionSet* humongous_proxy_set, 1056 HRRSCleanupTask* hrrs_cleanup_task, 1057 bool par); 1058 1059 // It appends the free list to the master free list and updates the 1060 // master humongous list according to the contents of the proxy 1061 // list. It also adjusts the total used bytes according to pre_used 1062 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1063 void update_sets_after_freeing_regions(size_t pre_used, 1064 FreeRegionList* free_list, 1065 HumongousRegionSet* humongous_proxy_set, 1066 bool par); 1067 1068 // Returns "TRUE" iff "p" points into the allocated area of the heap. 1069 virtual bool is_in(const void* p) const; 1070 1071 // Return "TRUE" iff the given object address is within the collection 1072 // set. 1073 inline bool obj_in_cs(oop obj); 1074 1075 // Return "TRUE" iff the given object address is in the reserved 1076 // region of g1 (excluding the permanent generation). 1077 bool is_in_g1_reserved(const void* p) const { 1078 return _g1_reserved.contains(p); 1079 } 1080 1081 // Returns a MemRegion that corresponds to the space that has been 1082 // reserved for the heap 1083 MemRegion g1_reserved() { 1084 return _g1_reserved; 1085 } 1086 1087 // Returns a MemRegion that corresponds to the space that has been 1088 // committed in the heap 1089 MemRegion g1_committed() { 1090 return _g1_committed; 1091 } 1092 1093 virtual bool is_in_closed_subset(const void* p) const; 1094 1095 // This resets the card table to all zeros. It is used after 1096 // a collection pause which used the card table to claim cards. 1097 void cleanUpCardTable(); 1098 1099 // Iteration functions. 1100 1101 // Iterate over all the ref-containing fields of all objects, calling 1102 // "cl.do_oop" on each. 1103 virtual void oop_iterate(OopClosure* cl) { 1104 oop_iterate(cl, true); 1105 } 1106 void oop_iterate(OopClosure* cl, bool do_perm); 1107 1108 // Same as above, restricted to a memory region. 1109 virtual void oop_iterate(MemRegion mr, OopClosure* cl) { 1110 oop_iterate(mr, cl, true); 1111 } 1112 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm); 1113 1114 // Iterate over all objects, calling "cl.do_object" on each. 1115 virtual void object_iterate(ObjectClosure* cl) { 1116 object_iterate(cl, true); 1117 } 1118 virtual void safe_object_iterate(ObjectClosure* cl) { 1119 object_iterate(cl, true); 1120 } 1121 void object_iterate(ObjectClosure* cl, bool do_perm); 1122 1123 // Iterate over all objects allocated since the last collection, calling 1124 // "cl.do_object" on each. The heap must have been initialized properly 1125 // to support this function, or else this call will fail. 1126 virtual void object_iterate_since_last_GC(ObjectClosure* cl); 1127 1128 // Iterate over all spaces in use in the heap, in ascending address order. 1129 virtual void space_iterate(SpaceClosure* cl); 1130 1131 // Iterate over heap regions, in address order, terminating the 1132 // iteration early if the "doHeapRegion" method returns "true". 1133 void heap_region_iterate(HeapRegionClosure* blk) const; 1134 1135 // Iterate over heap regions starting with r (or the first region if "r" 1136 // is NULL), in address order, terminating early if the "doHeapRegion" 1137 // method returns "true". 1138 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const; 1139 1140 // Return the region with the given index. It assumes the index is valid. 1141 HeapRegion* region_at(size_t index) const { return _hrs.at(index); } 1142 1143 // Divide the heap region sequence into "chunks" of some size (the number 1144 // of regions divided by the number of parallel threads times some 1145 // overpartition factor, currently 4). Assumes that this will be called 1146 // in parallel by ParallelGCThreads worker threads with discinct worker 1147 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1148 // calls will use the same "claim_value", and that that claim value is 1149 // different from the claim_value of any heap region before the start of 1150 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1151 // attempting to claim the first region in each chunk, and, if 1152 // successful, applying the closure to each region in the chunk (and 1153 // setting the claim value of the second and subsequent regions of the 1154 // chunk.) For now requires that "doHeapRegion" always returns "false", 1155 // i.e., that a closure never attempt to abort a traversal. 1156 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1157 int worker, 1158 jint claim_value); 1159 1160 // It resets all the region claim values to the default. 1161 void reset_heap_region_claim_values(); 1162 1163 #ifdef ASSERT 1164 bool check_heap_region_claim_values(jint claim_value); 1165 #endif // ASSERT 1166 1167 // Iterate over the regions (if any) in the current collection set. 1168 void collection_set_iterate(HeapRegionClosure* blk); 1169 1170 // As above but starting from region r 1171 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1172 1173 // Returns the first (lowest address) compactible space in the heap. 1174 virtual CompactibleSpace* first_compactible_space(); 1175 1176 // A CollectedHeap will contain some number of spaces. This finds the 1177 // space containing a given address, or else returns NULL. 1178 virtual Space* space_containing(const void* addr) const; 1179 1180 // A G1CollectedHeap will contain some number of heap regions. This 1181 // finds the region containing a given address, or else returns NULL. 1182 template <class T> 1183 inline HeapRegion* heap_region_containing(const T addr) const; 1184 1185 // Like the above, but requires "addr" to be in the heap (to avoid a 1186 // null-check), and unlike the above, may return an continuing humongous 1187 // region. 1188 template <class T> 1189 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1190 1191 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1192 // each address in the (reserved) heap is a member of exactly 1193 // one block. The defining characteristic of a block is that it is 1194 // possible to find its size, and thus to progress forward to the next 1195 // block. (Blocks may be of different sizes.) Thus, blocks may 1196 // represent Java objects, or they might be free blocks in a 1197 // free-list-based heap (or subheap), as long as the two kinds are 1198 // distinguishable and the size of each is determinable. 1199 1200 // Returns the address of the start of the "block" that contains the 1201 // address "addr". We say "blocks" instead of "object" since some heaps 1202 // may not pack objects densely; a chunk may either be an object or a 1203 // non-object. 1204 virtual HeapWord* block_start(const void* addr) const; 1205 1206 // Requires "addr" to be the start of a chunk, and returns its size. 1207 // "addr + size" is required to be the start of a new chunk, or the end 1208 // of the active area of the heap. 1209 virtual size_t block_size(const HeapWord* addr) const; 1210 1211 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1212 // the block is an object. 1213 virtual bool block_is_obj(const HeapWord* addr) const; 1214 1215 // Does this heap support heap inspection? (+PrintClassHistogram) 1216 virtual bool supports_heap_inspection() const { return true; } 1217 1218 // Section on thread-local allocation buffers (TLABs) 1219 // See CollectedHeap for semantics. 1220 1221 virtual bool supports_tlab_allocation() const; 1222 virtual size_t tlab_capacity(Thread* thr) const; 1223 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1224 1225 // Can a compiler initialize a new object without store barriers? 1226 // This permission only extends from the creation of a new object 1227 // via a TLAB up to the first subsequent safepoint. If such permission 1228 // is granted for this heap type, the compiler promises to call 1229 // defer_store_barrier() below on any slow path allocation of 1230 // a new object for which such initializing store barriers will 1231 // have been elided. G1, like CMS, allows this, but should be 1232 // ready to provide a compensating write barrier as necessary 1233 // if that storage came out of a non-young region. The efficiency 1234 // of this implementation depends crucially on being able to 1235 // answer very efficiently in constant time whether a piece of 1236 // storage in the heap comes from a young region or not. 1237 // See ReduceInitialCardMarks. 1238 virtual bool can_elide_tlab_store_barriers() const { 1239 // 6920090: Temporarily disabled, because of lingering 1240 // instabilities related to RICM with G1. In the 1241 // interim, the option ReduceInitialCardMarksForG1 1242 // below is left solely as a debugging device at least 1243 // until 6920109 fixes the instabilities. 1244 return ReduceInitialCardMarksForG1; 1245 } 1246 1247 virtual bool card_mark_must_follow_store() const { 1248 return true; 1249 } 1250 1251 bool is_in_young(const oop obj) { 1252 HeapRegion* hr = heap_region_containing(obj); 1253 return hr != NULL && hr->is_young(); 1254 } 1255 1256 #ifdef ASSERT 1257 virtual bool is_in_partial_collection(const void* p); 1258 #endif 1259 1260 virtual bool is_scavengable(const void* addr); 1261 1262 // We don't need barriers for initializing stores to objects 1263 // in the young gen: for the SATB pre-barrier, there is no 1264 // pre-value that needs to be remembered; for the remembered-set 1265 // update logging post-barrier, we don't maintain remembered set 1266 // information for young gen objects. Note that non-generational 1267 // G1 does not have any "young" objects, should not elide 1268 // the rs logging barrier and so should always answer false below. 1269 // However, non-generational G1 (-XX:-G1Gen) appears to have 1270 // bit-rotted so was not tested below. 1271 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1272 // Re 6920090, 6920109 above. 1273 assert(ReduceInitialCardMarksForG1, "Else cannot be here"); 1274 assert(G1Gen || !is_in_young(new_obj), 1275 "Non-generational G1 should never return true below"); 1276 return is_in_young(new_obj); 1277 } 1278 1279 // Can a compiler elide a store barrier when it writes 1280 // a permanent oop into the heap? Applies when the compiler 1281 // is storing x to the heap, where x->is_perm() is true. 1282 virtual bool can_elide_permanent_oop_store_barriers() const { 1283 // At least until perm gen collection is also G1-ified, at 1284 // which point this should return false. 1285 return true; 1286 } 1287 1288 // Returns "true" iff the given word_size is "very large". 1289 static bool isHumongous(size_t word_size) { 1290 // Note this has to be strictly greater-than as the TLABs 1291 // are capped at the humongous thresold and we want to 1292 // ensure that we don't try to allocate a TLAB as 1293 // humongous and that we don't allocate a humongous 1294 // object in a TLAB. 1295 return word_size > _humongous_object_threshold_in_words; 1296 } 1297 1298 // Update mod union table with the set of dirty cards. 1299 void updateModUnion(); 1300 1301 // Set the mod union bits corresponding to the given memRegion. Note 1302 // that this is always a safe operation, since it doesn't clear any 1303 // bits. 1304 void markModUnionRange(MemRegion mr); 1305 1306 // Records the fact that a marking phase is no longer in progress. 1307 void set_marking_complete() { 1308 _mark_in_progress = false; 1309 } 1310 void set_marking_started() { 1311 _mark_in_progress = true; 1312 } 1313 bool mark_in_progress() { 1314 return _mark_in_progress; 1315 } 1316 1317 // Print the maximum heap capacity. 1318 virtual size_t max_capacity() const; 1319 1320 virtual jlong millis_since_last_gc(); 1321 1322 // Perform any cleanup actions necessary before allowing a verification. 1323 virtual void prepare_for_verify(); 1324 1325 // Perform verification. 1326 1327 // vo == UsePrevMarking -> use "prev" marking information, 1328 // vo == UseNextMarking -> use "next" marking information 1329 // vo == UseMarkWord -> use the mark word in the object header 1330 // 1331 // NOTE: Only the "prev" marking information is guaranteed to be 1332 // consistent most of the time, so most calls to this should use 1333 // vo == UsePrevMarking. 1334 // Currently, there is only one case where this is called with 1335 // vo == UseNextMarking, which is to verify the "next" marking 1336 // information at the end of remark. 1337 // Currently there is only one place where this is called with 1338 // vo == UseMarkWord, which is to verify the marking during a 1339 // full GC. 1340 void verify(bool allow_dirty, bool silent, VerifyOption vo); 1341 1342 // Override; it uses the "prev" marking information 1343 virtual void verify(bool allow_dirty, bool silent); 1344 // Default behavior by calling print(tty); 1345 virtual void print() const; 1346 // This calls print_on(st, PrintHeapAtGCExtended). 1347 virtual void print_on(outputStream* st) const; 1348 // If extended is true, it will print out information for all 1349 // regions in the heap by calling print_on_extended(st). 1350 virtual void print_on(outputStream* st, bool extended) const; 1351 virtual void print_on_extended(outputStream* st) const; 1352 1353 virtual void print_gc_threads_on(outputStream* st) const; 1354 virtual void gc_threads_do(ThreadClosure* tc) const; 1355 1356 // Override 1357 void print_tracing_info() const; 1358 1359 // The following two methods are helpful for debugging RSet issues. 1360 void print_cset_rsets() PRODUCT_RETURN; 1361 void print_all_rsets() PRODUCT_RETURN; 1362 1363 // Convenience function to be used in situations where the heap type can be 1364 // asserted to be this type. 1365 static G1CollectedHeap* heap(); 1366 1367 void empty_young_list(); 1368 1369 void set_region_short_lived_locked(HeapRegion* hr); 1370 // add appropriate methods for any other surv rate groups 1371 1372 YoungList* young_list() { return _young_list; } 1373 1374 // debugging 1375 bool check_young_list_well_formed() { 1376 return _young_list->check_list_well_formed(); 1377 } 1378 1379 bool check_young_list_empty(bool check_heap, 1380 bool check_sample = true); 1381 1382 // *** Stuff related to concurrent marking. It's not clear to me that so 1383 // many of these need to be public. 1384 1385 // The functions below are helper functions that a subclass of 1386 // "CollectedHeap" can use in the implementation of its virtual 1387 // functions. 1388 // This performs a concurrent marking of the live objects in a 1389 // bitmap off to the side. 1390 void doConcurrentMark(); 1391 1392 // Do a full concurrent marking, synchronously. 1393 void do_sync_mark(); 1394 1395 bool isMarkedPrev(oop obj) const; 1396 bool isMarkedNext(oop obj) const; 1397 1398 // vo == UsePrevMarking -> use "prev" marking information, 1399 // vo == UseNextMarking -> use "next" marking information, 1400 // vo == UseMarkWord -> use mark word from object header 1401 bool is_obj_dead_cond(const oop obj, 1402 const HeapRegion* hr, 1403 const VerifyOption vo) const { 1404 1405 switch (vo) { 1406 case VerifyOption_G1UsePrevMarking: 1407 return is_obj_dead(obj, hr); 1408 case VerifyOption_G1UseNextMarking: 1409 return is_obj_ill(obj, hr); 1410 default: 1411 assert(vo == VerifyOption_G1UseMarkWord, "must be"); 1412 return !obj->is_gc_marked(); 1413 } 1414 } 1415 1416 // Determine if an object is dead, given the object and also 1417 // the region to which the object belongs. An object is dead 1418 // iff a) it was not allocated since the last mark and b) it 1419 // is not marked. 1420 1421 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1422 return 1423 !hr->obj_allocated_since_prev_marking(obj) && 1424 !isMarkedPrev(obj); 1425 } 1426 1427 // This is used when copying an object to survivor space. 1428 // If the object is marked live, then we mark the copy live. 1429 // If the object is allocated since the start of this mark 1430 // cycle, then we mark the copy live. 1431 // If the object has been around since the previous mark 1432 // phase, and hasn't been marked yet during this phase, 1433 // then we don't mark it, we just wait for the 1434 // current marking cycle to get to it. 1435 1436 // This function returns true when an object has been 1437 // around since the previous marking and hasn't yet 1438 // been marked during this marking. 1439 1440 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1441 return 1442 !hr->obj_allocated_since_next_marking(obj) && 1443 !isMarkedNext(obj); 1444 } 1445 1446 // Determine if an object is dead, given only the object itself. 1447 // This will find the region to which the object belongs and 1448 // then call the region version of the same function. 1449 1450 // Added if it is in permanent gen it isn't dead. 1451 // Added if it is NULL it isn't dead. 1452 1453 // vo == UsePrevMarking -> use "prev" marking information, 1454 // vo == UseNextMarking -> use "next" marking information, 1455 // vo == UseMarkWord -> use mark word from object header 1456 bool is_obj_dead_cond(const oop obj, 1457 const VerifyOption vo) const { 1458 1459 switch (vo) { 1460 case VerifyOption_G1UsePrevMarking: 1461 return is_obj_dead(obj); 1462 case VerifyOption_G1UseNextMarking: 1463 return is_obj_ill(obj); 1464 default: 1465 assert(vo == VerifyOption_G1UseMarkWord, "must be"); 1466 return !obj->is_gc_marked(); 1467 } 1468 } 1469 1470 bool is_obj_dead(const oop obj) const { 1471 const HeapRegion* hr = heap_region_containing(obj); 1472 if (hr == NULL) { 1473 if (Universe::heap()->is_in_permanent(obj)) 1474 return false; 1475 else if (obj == NULL) return false; 1476 else return true; 1477 } 1478 else return is_obj_dead(obj, hr); 1479 } 1480 1481 bool is_obj_ill(const oop obj) const { 1482 const HeapRegion* hr = heap_region_containing(obj); 1483 if (hr == NULL) { 1484 if (Universe::heap()->is_in_permanent(obj)) 1485 return false; 1486 else if (obj == NULL) return false; 1487 else return true; 1488 } 1489 else return is_obj_ill(obj, hr); 1490 } 1491 1492 // The following is just to alert the verification code 1493 // that a full collection has occurred and that the 1494 // remembered sets are no longer up to date. 1495 bool _full_collection; 1496 void set_full_collection() { _full_collection = true;} 1497 void clear_full_collection() {_full_collection = false;} 1498 bool full_collection() {return _full_collection;} 1499 1500 ConcurrentMark* concurrent_mark() const { return _cm; } 1501 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1502 1503 // The dirty cards region list is used to record a subset of regions 1504 // whose cards need clearing. The list if populated during the 1505 // remembered set scanning and drained during the card table 1506 // cleanup. Although the methods are reentrant, population/draining 1507 // phases must not overlap. For synchronization purposes the last 1508 // element on the list points to itself. 1509 HeapRegion* _dirty_cards_region_list; 1510 void push_dirty_cards_region(HeapRegion* hr); 1511 HeapRegion* pop_dirty_cards_region(); 1512 1513 public: 1514 void stop_conc_gc_threads(); 1515 1516 // <NEW PREDICTION> 1517 1518 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young); 1519 void check_if_region_is_too_expensive(double predicted_time_ms); 1520 size_t pending_card_num(); 1521 size_t max_pending_card_num(); 1522 size_t cards_scanned(); 1523 1524 // </NEW PREDICTION> 1525 1526 protected: 1527 size_t _max_heap_capacity; 1528 }; 1529 1530 #define use_local_bitmaps 1 1531 #define verify_local_bitmaps 0 1532 #define oop_buffer_length 256 1533 1534 #ifndef PRODUCT 1535 class GCLabBitMap; 1536 class GCLabBitMapClosure: public BitMapClosure { 1537 private: 1538 ConcurrentMark* _cm; 1539 GCLabBitMap* _bitmap; 1540 1541 public: 1542 GCLabBitMapClosure(ConcurrentMark* cm, 1543 GCLabBitMap* bitmap) { 1544 _cm = cm; 1545 _bitmap = bitmap; 1546 } 1547 1548 virtual bool do_bit(size_t offset); 1549 }; 1550 #endif // !PRODUCT 1551 1552 class GCLabBitMap: public BitMap { 1553 private: 1554 ConcurrentMark* _cm; 1555 1556 int _shifter; 1557 size_t _bitmap_word_covers_words; 1558 1559 // beginning of the heap 1560 HeapWord* _heap_start; 1561 1562 // this is the actual start of the GCLab 1563 HeapWord* _real_start_word; 1564 1565 // this is the actual end of the GCLab 1566 HeapWord* _real_end_word; 1567 1568 // this is the first word, possibly located before the actual start 1569 // of the GCLab, that corresponds to the first bit of the bitmap 1570 HeapWord* _start_word; 1571 1572 // size of a GCLab in words 1573 size_t _gclab_word_size; 1574 1575 static int shifter() { 1576 return MinObjAlignment - 1; 1577 } 1578 1579 // how many heap words does a single bitmap word corresponds to? 1580 static size_t bitmap_word_covers_words() { 1581 return BitsPerWord << shifter(); 1582 } 1583 1584 size_t gclab_word_size() const { 1585 return _gclab_word_size; 1586 } 1587 1588 // Calculates actual GCLab size in words 1589 size_t gclab_real_word_size() const { 1590 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word)) 1591 / BitsPerWord; 1592 } 1593 1594 static size_t bitmap_size_in_bits(size_t gclab_word_size) { 1595 size_t bits_in_bitmap = gclab_word_size >> shifter(); 1596 // We are going to ensure that the beginning of a word in this 1597 // bitmap also corresponds to the beginning of a word in the 1598 // global marking bitmap. To handle the case where a GCLab 1599 // starts from the middle of the bitmap, we need to add enough 1600 // space (i.e. up to a bitmap word) to ensure that we have 1601 // enough bits in the bitmap. 1602 return bits_in_bitmap + BitsPerWord - 1; 1603 } 1604 public: 1605 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size) 1606 : BitMap(bitmap_size_in_bits(gclab_word_size)), 1607 _cm(G1CollectedHeap::heap()->concurrent_mark()), 1608 _shifter(shifter()), 1609 _bitmap_word_covers_words(bitmap_word_covers_words()), 1610 _heap_start(heap_start), 1611 _gclab_word_size(gclab_word_size), 1612 _real_start_word(NULL), 1613 _real_end_word(NULL), 1614 _start_word(NULL) 1615 { 1616 guarantee( size_in_words() >= bitmap_size_in_words(), 1617 "just making sure"); 1618 } 1619 1620 inline unsigned heapWordToOffset(HeapWord* addr) { 1621 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter; 1622 assert(offset < size(), "offset should be within bounds"); 1623 return offset; 1624 } 1625 1626 inline HeapWord* offsetToHeapWord(size_t offset) { 1627 HeapWord* addr = _start_word + (offset << _shifter); 1628 assert(_real_start_word <= addr && addr < _real_end_word, "invariant"); 1629 return addr; 1630 } 1631 1632 bool fields_well_formed() { 1633 bool ret1 = (_real_start_word == NULL) && 1634 (_real_end_word == NULL) && 1635 (_start_word == NULL); 1636 if (ret1) 1637 return true; 1638 1639 bool ret2 = _real_start_word >= _start_word && 1640 _start_word < _real_end_word && 1641 (_real_start_word + _gclab_word_size) == _real_end_word && 1642 (_start_word + _gclab_word_size + _bitmap_word_covers_words) 1643 > _real_end_word; 1644 return ret2; 1645 } 1646 1647 inline bool mark(HeapWord* addr) { 1648 guarantee(use_local_bitmaps, "invariant"); 1649 assert(fields_well_formed(), "invariant"); 1650 1651 if (addr >= _real_start_word && addr < _real_end_word) { 1652 assert(!isMarked(addr), "should not have already been marked"); 1653 1654 // first mark it on the bitmap 1655 at_put(heapWordToOffset(addr), true); 1656 1657 return true; 1658 } else { 1659 return false; 1660 } 1661 } 1662 1663 inline bool isMarked(HeapWord* addr) { 1664 guarantee(use_local_bitmaps, "invariant"); 1665 assert(fields_well_formed(), "invariant"); 1666 1667 return at(heapWordToOffset(addr)); 1668 } 1669 1670 void set_buffer(HeapWord* start) { 1671 guarantee(use_local_bitmaps, "invariant"); 1672 clear(); 1673 1674 assert(start != NULL, "invariant"); 1675 _real_start_word = start; 1676 _real_end_word = start + _gclab_word_size; 1677 1678 size_t diff = 1679 pointer_delta(start, _heap_start) % _bitmap_word_covers_words; 1680 _start_word = start - diff; 1681 1682 assert(fields_well_formed(), "invariant"); 1683 } 1684 1685 #ifndef PRODUCT 1686 void verify() { 1687 // verify that the marks have been propagated 1688 GCLabBitMapClosure cl(_cm, this); 1689 iterate(&cl); 1690 } 1691 #endif // PRODUCT 1692 1693 void retire() { 1694 guarantee(use_local_bitmaps, "invariant"); 1695 assert(fields_well_formed(), "invariant"); 1696 1697 if (_start_word != NULL) { 1698 CMBitMap* mark_bitmap = _cm->nextMarkBitMap(); 1699 1700 // this means that the bitmap was set up for the GCLab 1701 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant"); 1702 1703 mark_bitmap->mostly_disjoint_range_union(this, 1704 0, // always start from the start of the bitmap 1705 _start_word, 1706 gclab_real_word_size()); 1707 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word)); 1708 1709 #ifndef PRODUCT 1710 if (use_local_bitmaps && verify_local_bitmaps) 1711 verify(); 1712 #endif // PRODUCT 1713 } else { 1714 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant"); 1715 } 1716 } 1717 1718 size_t bitmap_size_in_words() const { 1719 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord; 1720 } 1721 1722 }; 1723 1724 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1725 private: 1726 bool _retired; 1727 bool _during_marking; 1728 GCLabBitMap _bitmap; 1729 1730 public: 1731 G1ParGCAllocBuffer(size_t gclab_word_size) : 1732 ParGCAllocBuffer(gclab_word_size), 1733 _during_marking(G1CollectedHeap::heap()->mark_in_progress()), 1734 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size), 1735 _retired(false) 1736 { } 1737 1738 inline bool mark(HeapWord* addr) { 1739 guarantee(use_local_bitmaps, "invariant"); 1740 assert(_during_marking, "invariant"); 1741 return _bitmap.mark(addr); 1742 } 1743 1744 inline void set_buf(HeapWord* buf) { 1745 if (use_local_bitmaps && _during_marking) 1746 _bitmap.set_buffer(buf); 1747 ParGCAllocBuffer::set_buf(buf); 1748 _retired = false; 1749 } 1750 1751 inline void retire(bool end_of_gc, bool retain) { 1752 if (_retired) 1753 return; 1754 if (use_local_bitmaps && _during_marking) { 1755 _bitmap.retire(); 1756 } 1757 ParGCAllocBuffer::retire(end_of_gc, retain); 1758 _retired = true; 1759 } 1760 }; 1761 1762 class G1ParScanThreadState : public StackObj { 1763 protected: 1764 G1CollectedHeap* _g1h; 1765 RefToScanQueue* _refs; 1766 DirtyCardQueue _dcq; 1767 CardTableModRefBS* _ct_bs; 1768 G1RemSet* _g1_rem; 1769 1770 G1ParGCAllocBuffer _surviving_alloc_buffer; 1771 G1ParGCAllocBuffer _tenured_alloc_buffer; 1772 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount]; 1773 ageTable _age_table; 1774 1775 size_t _alloc_buffer_waste; 1776 size_t _undo_waste; 1777 1778 OopsInHeapRegionClosure* _evac_failure_cl; 1779 G1ParScanHeapEvacClosure* _evac_cl; 1780 G1ParScanPartialArrayClosure* _partial_scan_cl; 1781 1782 int _hash_seed; 1783 int _queue_num; 1784 1785 size_t _term_attempts; 1786 1787 double _start; 1788 double _start_strong_roots; 1789 double _strong_roots_time; 1790 double _start_term; 1791 double _term_time; 1792 1793 // Map from young-age-index (0 == not young, 1 is youngest) to 1794 // surviving words. base is what we get back from the malloc call 1795 size_t* _surviving_young_words_base; 1796 // this points into the array, as we use the first few entries for padding 1797 size_t* _surviving_young_words; 1798 1799 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1800 1801 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1802 1803 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1804 1805 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1806 CardTableModRefBS* ctbs() { return _ct_bs; } 1807 1808 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1809 if (!from->is_survivor()) { 1810 _g1_rem->par_write_ref(from, p, tid); 1811 } 1812 } 1813 1814 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1815 // If the new value of the field points to the same region or 1816 // is the to-space, we don't need to include it in the Rset updates. 1817 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1818 size_t card_index = ctbs()->index_for(p); 1819 // If the card hasn't been added to the buffer, do it. 1820 if (ctbs()->mark_card_deferred(card_index)) { 1821 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1822 } 1823 } 1824 } 1825 1826 public: 1827 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num); 1828 1829 ~G1ParScanThreadState() { 1830 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 1831 } 1832 1833 RefToScanQueue* refs() { return _refs; } 1834 ageTable* age_table() { return &_age_table; } 1835 1836 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) { 1837 return _alloc_buffers[purpose]; 1838 } 1839 1840 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1841 size_t undo_waste() const { return _undo_waste; } 1842 1843 #ifdef ASSERT 1844 bool verify_ref(narrowOop* ref) const; 1845 bool verify_ref(oop* ref) const; 1846 bool verify_task(StarTask ref) const; 1847 #endif // ASSERT 1848 1849 template <class T> void push_on_queue(T* ref) { 1850 assert(verify_ref(ref), "sanity"); 1851 refs()->push(ref); 1852 } 1853 1854 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1855 if (G1DeferredRSUpdate) { 1856 deferred_rs_update(from, p, tid); 1857 } else { 1858 immediate_rs_update(from, p, tid); 1859 } 1860 } 1861 1862 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1863 1864 HeapWord* obj = NULL; 1865 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1866 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1867 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose); 1868 assert(gclab_word_size == alloc_buf->word_sz(), 1869 "dynamic resizing is not supported"); 1870 add_to_alloc_buffer_waste(alloc_buf->words_remaining()); 1871 alloc_buf->retire(false, false); 1872 1873 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1874 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1875 // Otherwise. 1876 alloc_buf->set_buf(buf); 1877 1878 obj = alloc_buf->allocate(word_sz); 1879 assert(obj != NULL, "buffer was definitely big enough..."); 1880 } else { 1881 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1882 } 1883 return obj; 1884 } 1885 1886 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1887 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1888 if (obj != NULL) return obj; 1889 return allocate_slow(purpose, word_sz); 1890 } 1891 1892 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1893 if (alloc_buffer(purpose)->contains(obj)) { 1894 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 1895 "should contain whole object"); 1896 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 1897 } else { 1898 CollectedHeap::fill_with_object(obj, word_sz); 1899 add_to_undo_waste(word_sz); 1900 } 1901 } 1902 1903 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 1904 _evac_failure_cl = evac_failure_cl; 1905 } 1906 OopsInHeapRegionClosure* evac_failure_closure() { 1907 return _evac_failure_cl; 1908 } 1909 1910 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 1911 _evac_cl = evac_cl; 1912 } 1913 1914 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 1915 _partial_scan_cl = partial_scan_cl; 1916 } 1917 1918 int* hash_seed() { return &_hash_seed; } 1919 int queue_num() { return _queue_num; } 1920 1921 size_t term_attempts() const { return _term_attempts; } 1922 void note_term_attempt() { _term_attempts++; } 1923 1924 void start_strong_roots() { 1925 _start_strong_roots = os::elapsedTime(); 1926 } 1927 void end_strong_roots() { 1928 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 1929 } 1930 double strong_roots_time() const { return _strong_roots_time; } 1931 1932 void start_term_time() { 1933 note_term_attempt(); 1934 _start_term = os::elapsedTime(); 1935 } 1936 void end_term_time() { 1937 _term_time += (os::elapsedTime() - _start_term); 1938 } 1939 double term_time() const { return _term_time; } 1940 1941 double elapsed_time() const { 1942 return os::elapsedTime() - _start; 1943 } 1944 1945 static void 1946 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 1947 void 1948 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 1949 1950 size_t* surviving_young_words() { 1951 // We add on to hide entry 0 which accumulates surviving words for 1952 // age -1 regions (i.e. non-young ones) 1953 return _surviving_young_words; 1954 } 1955 1956 void retire_alloc_buffers() { 1957 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 1958 size_t waste = _alloc_buffers[ap]->words_remaining(); 1959 add_to_alloc_buffer_waste(waste); 1960 _alloc_buffers[ap]->retire(true, false); 1961 } 1962 } 1963 1964 template <class T> void deal_with_reference(T* ref_to_scan) { 1965 if (has_partial_array_mask(ref_to_scan)) { 1966 _partial_scan_cl->do_oop_nv(ref_to_scan); 1967 } else { 1968 // Note: we can use "raw" versions of "region_containing" because 1969 // "obj_to_scan" is definitely in the heap, and is not in a 1970 // humongous region. 1971 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 1972 _evac_cl->set_region(r); 1973 _evac_cl->do_oop_nv(ref_to_scan); 1974 } 1975 } 1976 1977 void deal_with_reference(StarTask ref) { 1978 assert(verify_task(ref), "sanity"); 1979 if (ref.is_narrow()) { 1980 deal_with_reference((narrowOop*)ref); 1981 } else { 1982 deal_with_reference((oop*)ref); 1983 } 1984 } 1985 1986 public: 1987 void trim_queue(); 1988 }; 1989 1990 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP