1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/concurrentMark.hpp" 29 #include "gc/g1/evacuationInfo.hpp" 30 #include "gc/g1/g1AllocationContext.hpp" 31 #include "gc/g1/g1BiasedArray.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1HRPrinter.hpp" 34 #include "gc/g1/g1InCSetState.hpp" 35 #include "gc/g1/g1MonitoringSupport.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 38 #include "gc/g1/g1YCTypes.hpp" 39 #include "gc/g1/hSpaceCounters.hpp" 40 #include "gc/g1/heapRegionManager.hpp" 41 #include "gc/g1/heapRegionSet.hpp" 42 #include "gc/g1/youngList.hpp" 43 #include "gc/shared/barrierSet.hpp" 44 #include "gc/shared/collectedHeap.hpp" 45 #include "gc/shared/plab.hpp" 46 #include "memory/memRegion.hpp" 47 #include "utilities/stack.hpp" 48 49 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 50 // It uses the "Garbage First" heap organization and algorithm, which 51 // may combine concurrent marking with parallel, incremental compaction of 52 // heap subsets that will yield large amounts of garbage. 53 54 // Forward declarations 55 class HeapRegion; 56 class HRRSCleanupTask; 57 class GenerationSpec; 58 class OopsInHeapRegionClosure; 59 class G1ParScanThreadState; 60 class G1ParScanThreadStateSet; 61 class G1KlassScanClosure; 62 class G1ParScanThreadState; 63 class ObjectClosure; 64 class SpaceClosure; 65 class CompactibleSpaceClosure; 66 class Space; 67 class G1CollectorPolicy; 68 class G1RemSet; 69 class HeapRegionRemSetIterator; 70 class ConcurrentMark; 71 class ConcurrentMarkThread; 72 class ConcurrentG1Refine; 73 class ConcurrentGCTimer; 74 class GenerationCounters; 75 class STWGCTimer; 76 class G1NewTracer; 77 class G1OldTracer; 78 class EvacuationFailedInfo; 79 class nmethod; 80 class Ticks; 81 class WorkGang; 82 class G1Allocator; 83 class G1ArchiveAllocator; 84 85 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 86 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 87 88 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 89 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 90 91 // The G1 STW is alive closure. 92 // An instance is embedded into the G1CH and used as the 93 // (optional) _is_alive_non_header closure in the STW 94 // reference processor. It is also extensively used during 95 // reference processing during STW evacuation pauses. 96 class G1STWIsAliveClosure: public BoolObjectClosure { 97 G1CollectedHeap* _g1; 98 public: 99 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 100 bool do_object_b(oop p); 101 }; 102 103 class RefineCardTableEntryClosure; 104 105 class G1RegionMappingChangedListener : public G1MappingChangedListener { 106 private: 107 void reset_from_card_cache(uint start_idx, size_t num_regions); 108 public: 109 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 110 }; 111 112 class G1CollectedHeap : public CollectedHeap { 113 friend class VM_CollectForMetadataAllocation; 114 friend class VM_G1CollectForAllocation; 115 friend class VM_G1CollectFull; 116 friend class VM_G1IncCollectionPause; 117 friend class VMStructs; 118 friend class MutatorAllocRegion; 119 friend class G1GCAllocRegion; 120 121 // Closures used in implementation. 122 friend class G1ParScanThreadState; 123 friend class G1ParScanThreadStateSet; 124 friend class G1ParTask; 125 friend class G1PLABAllocator; 126 friend class G1PrepareCompactClosure; 127 128 // Other related classes. 129 friend class HeapRegionClaimer; 130 131 // Testing classes. 132 friend class G1CheckCSetFastTableClosure; 133 134 private: 135 WorkGang* _workers; 136 137 static size_t _humongous_object_threshold_in_words; 138 139 // The secondary free list which contains regions that have been 140 // freed up during the cleanup process. This will be appended to 141 // the master free list when appropriate. 142 FreeRegionList _secondary_free_list; 143 144 // It keeps track of the old regions. 145 HeapRegionSet _old_set; 146 147 // It keeps track of the humongous regions. 148 HeapRegionSet _humongous_set; 149 150 void eagerly_reclaim_humongous_regions(); 151 152 // The number of regions we could create by expansion. 153 uint _expansion_regions; 154 155 // The block offset table for the G1 heap. 156 G1BlockOffsetSharedArray* _bot_shared; 157 158 // Tears down the region sets / lists so that they are empty and the 159 // regions on the heap do not belong to a region set / list. The 160 // only exception is the humongous set which we leave unaltered. If 161 // free_list_only is true, it will only tear down the master free 162 // list. It is called before a Full GC (free_list_only == false) or 163 // before heap shrinking (free_list_only == true). 164 void tear_down_region_sets(bool free_list_only); 165 166 // Rebuilds the region sets / lists so that they are repopulated to 167 // reflect the contents of the heap. The only exception is the 168 // humongous set which was not torn down in the first place. If 169 // free_list_only is true, it will only rebuild the master free 170 // list. It is called after a Full GC (free_list_only == false) or 171 // after heap shrinking (free_list_only == true). 172 void rebuild_region_sets(bool free_list_only); 173 174 // Callback for region mapping changed events. 175 G1RegionMappingChangedListener _listener; 176 177 // The sequence of all heap regions in the heap. 178 HeapRegionManager _hrm; 179 180 // Manages all allocations with regions except humongous object allocations. 181 G1Allocator* _allocator; 182 183 // Outside of GC pauses, the number of bytes used in all regions other 184 // than the current allocation region(s). 185 size_t _summary_bytes_used; 186 187 void increase_used(size_t bytes); 188 void decrease_used(size_t bytes); 189 190 void set_used(size_t bytes); 191 192 // Class that handles archive allocation ranges. 193 G1ArchiveAllocator* _archive_allocator; 194 195 // Statistics for each allocation context 196 AllocationContextStats _allocation_context_stats; 197 198 // GC allocation statistics policy for survivors. 199 G1EvacStats _survivor_evac_stats; 200 201 // GC allocation statistics policy for tenured objects. 202 G1EvacStats _old_evac_stats; 203 204 // It specifies whether we should attempt to expand the heap after a 205 // region allocation failure. If heap expansion fails we set this to 206 // false so that we don't re-attempt the heap expansion (it's likely 207 // that subsequent expansion attempts will also fail if one fails). 208 // Currently, it is only consulted during GC and it's reset at the 209 // start of each GC. 210 bool _expand_heap_after_alloc_failure; 211 212 // Helper for monitoring and management support. 213 G1MonitoringSupport* _g1mm; 214 215 // Records whether the region at the given index is (still) a 216 // candidate for eager reclaim. Only valid for humongous start 217 // regions; other regions have unspecified values. Humongous start 218 // regions are initialized at start of collection pause, with 219 // candidates removed from the set as they are found reachable from 220 // roots or the young generation. 221 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 222 protected: 223 bool default_value() const { return false; } 224 public: 225 void clear() { G1BiasedMappedArray<bool>::clear(); } 226 void set_candidate(uint region, bool value) { 227 set_by_index(region, value); 228 } 229 bool is_candidate(uint region) { 230 return get_by_index(region); 231 } 232 }; 233 234 HumongousReclaimCandidates _humongous_reclaim_candidates; 235 // Stores whether during humongous object registration we found candidate regions. 236 // If not, we can skip a few steps. 237 bool _has_humongous_reclaim_candidates; 238 239 volatile unsigned _gc_time_stamp; 240 241 G1HRPrinter _hr_printer; 242 243 // It decides whether an explicit GC should start a concurrent cycle 244 // instead of doing a STW GC. Currently, a concurrent cycle is 245 // explicitly started if: 246 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 247 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 248 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 249 // (d) cause == _g1_humongous_allocation 250 bool should_do_concurrent_full_gc(GCCause::Cause cause); 251 252 // indicates whether we are in young or mixed GC mode 253 G1CollectorState _collector_state; 254 255 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 256 // concurrent cycles) we have started. 257 volatile uint _old_marking_cycles_started; 258 259 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 260 // concurrent cycles) we have completed. 261 volatile uint _old_marking_cycles_completed; 262 263 bool _heap_summary_sent; 264 265 // This is a non-product method that is helpful for testing. It is 266 // called at the end of a GC and artificially expands the heap by 267 // allocating a number of dead regions. This way we can induce very 268 // frequent marking cycles and stress the cleanup / concurrent 269 // cleanup code more (as all the regions that will be allocated by 270 // this method will be found dead by the marking cycle). 271 void allocate_dummy_regions() PRODUCT_RETURN; 272 273 // Clear RSets after a compaction. It also resets the GC time stamps. 274 void clear_rsets_post_compaction(); 275 276 // If the HR printer is active, dump the state of the regions in the 277 // heap after a compaction. 278 void print_hrm_post_compaction(); 279 280 // Create a memory mapper for auxiliary data structures of the given size and 281 // translation factor. 282 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 283 size_t size, 284 size_t translation_factor); 285 286 double verify(bool guard, const char* msg); 287 void verify_before_gc(); 288 void verify_after_gc(); 289 290 void log_gc_header(); 291 void log_gc_footer(double pause_time_sec); 292 293 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 294 295 // These are macros so that, if the assert fires, we get the correct 296 // line number, file, etc. 297 298 #define heap_locking_asserts_params(_extra_message_) \ 299 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 300 (_extra_message_), \ 301 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 302 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 303 BOOL_TO_STR(Thread::current()->is_VM_thread()) 304 305 #define assert_heap_locked() \ 306 do { \ 307 assert(Heap_lock->owned_by_self(), \ 308 heap_locking_asserts_params("should be holding the Heap_lock")); \ 309 } while (0) 310 311 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 312 do { \ 313 assert(Heap_lock->owned_by_self() || \ 314 (SafepointSynchronize::is_at_safepoint() && \ 315 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 316 heap_locking_asserts_params("should be holding the Heap_lock or " \ 317 "should be at a safepoint")); \ 318 } while (0) 319 320 #define assert_heap_locked_and_not_at_safepoint() \ 321 do { \ 322 assert(Heap_lock->owned_by_self() && \ 323 !SafepointSynchronize::is_at_safepoint(), \ 324 heap_locking_asserts_params("should be holding the Heap_lock and " \ 325 "should not be at a safepoint")); \ 326 } while (0) 327 328 #define assert_heap_not_locked() \ 329 do { \ 330 assert(!Heap_lock->owned_by_self(), \ 331 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 332 } while (0) 333 334 #define assert_heap_not_locked_and_not_at_safepoint() \ 335 do { \ 336 assert(!Heap_lock->owned_by_self() && \ 337 !SafepointSynchronize::is_at_safepoint(), \ 338 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 339 "should not be at a safepoint")); \ 340 } while (0) 341 342 #define assert_at_safepoint(_should_be_vm_thread_) \ 343 do { \ 344 assert(SafepointSynchronize::is_at_safepoint() && \ 345 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 346 heap_locking_asserts_params("should be at a safepoint")); \ 347 } while (0) 348 349 #define assert_not_at_safepoint() \ 350 do { \ 351 assert(!SafepointSynchronize::is_at_safepoint(), \ 352 heap_locking_asserts_params("should not be at a safepoint")); \ 353 } while (0) 354 355 protected: 356 357 // The young region list. 358 YoungList* _young_list; 359 360 // The current policy object for the collector. 361 G1CollectorPolicy* _g1_policy; 362 363 // This is the second level of trying to allocate a new region. If 364 // new_region() didn't find a region on the free_list, this call will 365 // check whether there's anything available on the 366 // secondary_free_list and/or wait for more regions to appear on 367 // that list, if _free_regions_coming is set. 368 HeapRegion* new_region_try_secondary_free_list(bool is_old); 369 370 // Try to allocate a single non-humongous HeapRegion sufficient for 371 // an allocation of the given word_size. If do_expand is true, 372 // attempt to expand the heap if necessary to satisfy the allocation 373 // request. If the region is to be used as an old region or for a 374 // humongous object, set is_old to true. If not, to false. 375 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 376 377 // Initialize a contiguous set of free regions of length num_regions 378 // and starting at index first so that they appear as a single 379 // humongous region. 380 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 381 uint num_regions, 382 size_t word_size, 383 AllocationContext_t context); 384 385 // Attempt to allocate a humongous object of the given size. Return 386 // NULL if unsuccessful. 387 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 388 389 // The following two methods, allocate_new_tlab() and 390 // mem_allocate(), are the two main entry points from the runtime 391 // into the G1's allocation routines. They have the following 392 // assumptions: 393 // 394 // * They should both be called outside safepoints. 395 // 396 // * They should both be called without holding the Heap_lock. 397 // 398 // * All allocation requests for new TLABs should go to 399 // allocate_new_tlab(). 400 // 401 // * All non-TLAB allocation requests should go to mem_allocate(). 402 // 403 // * If either call cannot satisfy the allocation request using the 404 // current allocating region, they will try to get a new one. If 405 // this fails, they will attempt to do an evacuation pause and 406 // retry the allocation. 407 // 408 // * If all allocation attempts fail, even after trying to schedule 409 // an evacuation pause, allocate_new_tlab() will return NULL, 410 // whereas mem_allocate() will attempt a heap expansion and/or 411 // schedule a Full GC. 412 // 413 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 414 // should never be called with word_size being humongous. All 415 // humongous allocation requests should go to mem_allocate() which 416 // will satisfy them with a special path. 417 418 virtual HeapWord* allocate_new_tlab(size_t word_size); 419 420 virtual HeapWord* mem_allocate(size_t word_size, 421 bool* gc_overhead_limit_was_exceeded); 422 423 // The following three methods take a gc_count_before_ret 424 // parameter which is used to return the GC count if the method 425 // returns NULL. Given that we are required to read the GC count 426 // while holding the Heap_lock, and these paths will take the 427 // Heap_lock at some point, it's easier to get them to read the GC 428 // count while holding the Heap_lock before they return NULL instead 429 // of the caller (namely: mem_allocate()) having to also take the 430 // Heap_lock just to read the GC count. 431 432 // First-level mutator allocation attempt: try to allocate out of 433 // the mutator alloc region without taking the Heap_lock. This 434 // should only be used for non-humongous allocations. 435 inline HeapWord* attempt_allocation(size_t word_size, 436 uint* gc_count_before_ret, 437 uint* gclocker_retry_count_ret); 438 439 // Second-level mutator allocation attempt: take the Heap_lock and 440 // retry the allocation attempt, potentially scheduling a GC 441 // pause. This should only be used for non-humongous allocations. 442 HeapWord* attempt_allocation_slow(size_t word_size, 443 AllocationContext_t context, 444 uint* gc_count_before_ret, 445 uint* gclocker_retry_count_ret); 446 447 // Takes the Heap_lock and attempts a humongous allocation. It can 448 // potentially schedule a GC pause. 449 HeapWord* attempt_allocation_humongous(size_t word_size, 450 uint* gc_count_before_ret, 451 uint* gclocker_retry_count_ret); 452 453 // Allocation attempt that should be called during safepoints (e.g., 454 // at the end of a successful GC). expect_null_mutator_alloc_region 455 // specifies whether the mutator alloc region is expected to be NULL 456 // or not. 457 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 458 AllocationContext_t context, 459 bool expect_null_mutator_alloc_region); 460 461 // These methods are the "callbacks" from the G1AllocRegion class. 462 463 // For mutator alloc regions. 464 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 465 void retire_mutator_alloc_region(HeapRegion* alloc_region, 466 size_t allocated_bytes); 467 468 // For GC alloc regions. 469 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 470 InCSetState dest); 471 void retire_gc_alloc_region(HeapRegion* alloc_region, 472 size_t allocated_bytes, InCSetState dest); 473 474 // - if explicit_gc is true, the GC is for a System.gc() or a heap 475 // inspection request and should collect the entire heap 476 // - if clear_all_soft_refs is true, all soft references should be 477 // cleared during the GC 478 // - if explicit_gc is false, word_size describes the allocation that 479 // the GC should attempt (at least) to satisfy 480 // - it returns false if it is unable to do the collection due to the 481 // GC locker being active, true otherwise 482 bool do_collection(bool explicit_gc, 483 bool clear_all_soft_refs, 484 size_t word_size); 485 486 // Callback from VM_G1CollectFull operation. 487 // Perform a full collection. 488 virtual void do_full_collection(bool clear_all_soft_refs); 489 490 // Resize the heap if necessary after a full collection. If this is 491 // after a collect-for allocation, "word_size" is the allocation size, 492 // and will be considered part of the used portion of the heap. 493 void resize_if_necessary_after_full_collection(size_t word_size); 494 495 // Callback from VM_G1CollectForAllocation operation. 496 // This function does everything necessary/possible to satisfy a 497 // failed allocation request (including collection, expansion, etc.) 498 HeapWord* satisfy_failed_allocation(size_t word_size, 499 AllocationContext_t context, 500 bool* succeeded); 501 private: 502 // Helper method for satisfy_failed_allocation() 503 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 504 AllocationContext_t context, 505 bool do_gc, 506 bool clear_all_soft_refs, 507 bool expect_null_mutator_alloc_region, 508 bool* gc_succeeded); 509 510 protected: 511 // Attempting to expand the heap sufficiently 512 // to support an allocation of the given "word_size". If 513 // successful, perform the allocation and return the address of the 514 // allocated block, or else "NULL". 515 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 516 517 // Process any reference objects discovered during 518 // an incremental evacuation pause. 519 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 520 521 // Enqueue any remaining discovered references 522 // after processing. 523 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 524 525 public: 526 WorkGang* workers() const { return _workers; } 527 528 G1Allocator* allocator() { 529 return _allocator; 530 } 531 532 G1MonitoringSupport* g1mm() { 533 assert(_g1mm != NULL, "should have been initialized"); 534 return _g1mm; 535 } 536 537 // Expand the garbage-first heap by at least the given size (in bytes!). 538 // Returns true if the heap was expanded by the requested amount; 539 // false otherwise. 540 // (Rounds up to a HeapRegion boundary.) 541 bool expand(size_t expand_bytes, double* expand_time_ms = NULL); 542 543 // Returns the PLAB statistics for a given destination. 544 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 545 546 // Determines PLAB size for a given destination. 547 inline size_t desired_plab_sz(InCSetState dest); 548 549 inline AllocationContextStats& allocation_context_stats(); 550 551 // Do anything common to GC's. 552 void gc_prologue(bool full); 553 void gc_epilogue(bool full); 554 555 // Modify the reclaim candidate set and test for presence. 556 // These are only valid for starts_humongous regions. 557 inline void set_humongous_reclaim_candidate(uint region, bool value); 558 inline bool is_humongous_reclaim_candidate(uint region); 559 560 // Remove from the reclaim candidate set. Also remove from the 561 // collection set so that later encounters avoid the slow path. 562 inline void set_humongous_is_live(oop obj); 563 564 // Register the given region to be part of the collection set. 565 inline void register_humongous_region_with_cset(uint index); 566 // Register regions with humongous objects (actually on the start region) in 567 // the in_cset_fast_test table. 568 void register_humongous_regions_with_cset(); 569 // We register a region with the fast "in collection set" test. We 570 // simply set to true the array slot corresponding to this region. 571 void register_young_region_with_cset(HeapRegion* r) { 572 _in_cset_fast_test.set_in_young(r->hrm_index()); 573 } 574 void register_old_region_with_cset(HeapRegion* r) { 575 _in_cset_fast_test.set_in_old(r->hrm_index()); 576 } 577 void clear_in_cset(const HeapRegion* hr) { 578 _in_cset_fast_test.clear(hr); 579 } 580 581 void clear_cset_fast_test() { 582 _in_cset_fast_test.clear(); 583 } 584 585 // This is called at the start of either a concurrent cycle or a Full 586 // GC to update the number of old marking cycles started. 587 void increment_old_marking_cycles_started(); 588 589 // This is called at the end of either a concurrent cycle or a Full 590 // GC to update the number of old marking cycles completed. Those two 591 // can happen in a nested fashion, i.e., we start a concurrent 592 // cycle, a Full GC happens half-way through it which ends first, 593 // and then the cycle notices that a Full GC happened and ends 594 // too. The concurrent parameter is a boolean to help us do a bit 595 // tighter consistency checking in the method. If concurrent is 596 // false, the caller is the inner caller in the nesting (i.e., the 597 // Full GC). If concurrent is true, the caller is the outer caller 598 // in this nesting (i.e., the concurrent cycle). Further nesting is 599 // not currently supported. The end of this call also notifies 600 // the FullGCCount_lock in case a Java thread is waiting for a full 601 // GC to happen (e.g., it called System.gc() with 602 // +ExplicitGCInvokesConcurrent). 603 void increment_old_marking_cycles_completed(bool concurrent); 604 605 uint old_marking_cycles_completed() { 606 return _old_marking_cycles_completed; 607 } 608 609 void register_concurrent_cycle_start(const Ticks& start_time); 610 void register_concurrent_cycle_end(); 611 void trace_heap_after_concurrent_cycle(); 612 613 G1HRPrinter* hr_printer() { return &_hr_printer; } 614 615 // Allocates a new heap region instance. 616 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 617 618 // Allocate the highest free region in the reserved heap. This will commit 619 // regions as necessary. 620 HeapRegion* alloc_highest_free_region(); 621 622 // Frees a non-humongous region by initializing its contents and 623 // adding it to the free list that's passed as a parameter (this is 624 // usually a local list which will be appended to the master free 625 // list later). The used bytes of freed regions are accumulated in 626 // pre_used. If par is true, the region's RSet will not be freed 627 // up. The assumption is that this will be done later. 628 // The locked parameter indicates if the caller has already taken 629 // care of proper synchronization. This may allow some optimizations. 630 void free_region(HeapRegion* hr, 631 FreeRegionList* free_list, 632 bool par, 633 bool locked = false); 634 635 // It dirties the cards that cover the block so that the post 636 // write barrier never queues anything when updating objects on this 637 // block. It is assumed (and in fact we assert) that the block 638 // belongs to a young region. 639 inline void dirty_young_block(HeapWord* start, size_t word_size); 640 641 // Frees a humongous region by collapsing it into individual regions 642 // and calling free_region() for each of them. The freed regions 643 // will be added to the free list that's passed as a parameter (this 644 // is usually a local list which will be appended to the master free 645 // list later). The used bytes of freed regions are accumulated in 646 // pre_used. If par is true, the region's RSet will not be freed 647 // up. The assumption is that this will be done later. 648 void free_humongous_region(HeapRegion* hr, 649 FreeRegionList* free_list, 650 bool par); 651 652 // Facility for allocating in 'archive' regions in high heap memory and 653 // recording the allocated ranges. These should all be called from the 654 // VM thread at safepoints, without the heap lock held. They can be used 655 // to create and archive a set of heap regions which can be mapped at the 656 // same fixed addresses in a subsequent JVM invocation. 657 void begin_archive_alloc_range(); 658 659 // Check if the requested size would be too large for an archive allocation. 660 bool is_archive_alloc_too_large(size_t word_size); 661 662 // Allocate memory of the requested size from the archive region. This will 663 // return NULL if the size is too large or if no memory is available. It 664 // does not trigger a garbage collection. 665 HeapWord* archive_mem_allocate(size_t word_size); 666 667 // Optionally aligns the end address and returns the allocated ranges in 668 // an array of MemRegions in order of ascending addresses. 669 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 670 size_t end_alignment_in_bytes = 0); 671 672 // Facility for allocating a fixed range within the heap and marking 673 // the containing regions as 'archive'. For use at JVM init time, when the 674 // caller may mmap archived heap data at the specified range(s). 675 // Verify that the MemRegions specified in the argument array are within the 676 // reserved heap. 677 bool check_archive_addresses(MemRegion* range, size_t count); 678 679 // Commit the appropriate G1 regions containing the specified MemRegions 680 // and mark them as 'archive' regions. The regions in the array must be 681 // non-overlapping and in order of ascending address. 682 bool alloc_archive_regions(MemRegion* range, size_t count); 683 684 // Insert any required filler objects in the G1 regions around the specified 685 // ranges to make the regions parseable. This must be called after 686 // alloc_archive_regions, and after class loading has occurred. 687 void fill_archive_regions(MemRegion* range, size_t count); 688 689 // For each of the specified MemRegions, uncommit the containing G1 regions 690 // which had been allocated by alloc_archive_regions. This should be called 691 // rather than fill_archive_regions at JVM init time if the archive file 692 // mapping failed, with the same non-overlapping and sorted MemRegion array. 693 void dealloc_archive_regions(MemRegion* range, size_t count); 694 695 protected: 696 697 // Shrink the garbage-first heap by at most the given size (in bytes!). 698 // (Rounds down to a HeapRegion boundary.) 699 virtual void shrink(size_t expand_bytes); 700 void shrink_helper(size_t expand_bytes); 701 702 #if TASKQUEUE_STATS 703 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 704 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 705 void reset_taskqueue_stats(); 706 #endif // TASKQUEUE_STATS 707 708 // Schedule the VM operation that will do an evacuation pause to 709 // satisfy an allocation request of word_size. *succeeded will 710 // return whether the VM operation was successful (it did do an 711 // evacuation pause) or not (another thread beat us to it or the GC 712 // locker was active). Given that we should not be holding the 713 // Heap_lock when we enter this method, we will pass the 714 // gc_count_before (i.e., total_collections()) as a parameter since 715 // it has to be read while holding the Heap_lock. Currently, both 716 // methods that call do_collection_pause() release the Heap_lock 717 // before the call, so it's easy to read gc_count_before just before. 718 HeapWord* do_collection_pause(size_t word_size, 719 uint gc_count_before, 720 bool* succeeded, 721 GCCause::Cause gc_cause); 722 723 void wait_for_root_region_scanning(); 724 725 // The guts of the incremental collection pause, executed by the vm 726 // thread. It returns false if it is unable to do the collection due 727 // to the GC locker being active, true otherwise 728 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 729 730 // Actually do the work of evacuating the collection set. 731 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 732 733 void pre_evacuate_collection_set(); 734 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 735 736 // Print the header for the per-thread termination statistics. 737 static void print_termination_stats_hdr(outputStream* const st); 738 // Print actual per-thread termination statistics. 739 void print_termination_stats(outputStream* const st, 740 uint worker_id, 741 double elapsed_ms, 742 double strong_roots_ms, 743 double term_ms, 744 size_t term_attempts, 745 size_t alloc_buffer_waste, 746 size_t undo_waste) const; 747 // Update object copying statistics. 748 void record_obj_copy_mem_stats(); 749 750 // The g1 remembered set of the heap. 751 G1RemSet* _g1_rem_set; 752 753 // A set of cards that cover the objects for which the Rsets should be updated 754 // concurrently after the collection. 755 DirtyCardQueueSet _dirty_card_queue_set; 756 757 // The closure used to refine a single card. 758 RefineCardTableEntryClosure* _refine_cte_cl; 759 760 // A DirtyCardQueueSet that is used to hold cards that contain 761 // references into the current collection set. This is used to 762 // update the remembered sets of the regions in the collection 763 // set in the event of an evacuation failure. 764 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 765 766 // After a collection pause, make the regions in the CS into free 767 // regions. 768 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 769 770 // Abandon the current collection set without recording policy 771 // statistics or updating free lists. 772 void abandon_collection_set(HeapRegion* cs_head); 773 774 // The concurrent marker (and the thread it runs in.) 775 ConcurrentMark* _cm; 776 ConcurrentMarkThread* _cmThread; 777 778 // The concurrent refiner. 779 ConcurrentG1Refine* _cg1r; 780 781 // The parallel task queues 782 RefToScanQueueSet *_task_queues; 783 784 // True iff a evacuation has failed in the current collection. 785 bool _evacuation_failed; 786 787 EvacuationFailedInfo* _evacuation_failed_info_array; 788 789 // Failed evacuations cause some logical from-space objects to have 790 // forwarding pointers to themselves. Reset them. 791 void remove_self_forwarding_pointers(); 792 793 struct OopAndMarkOop { 794 private: 795 oop _o; 796 markOop _m; 797 public: 798 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { 799 } 800 801 void set_mark() { 802 _o->set_mark(_m); 803 } 804 }; 805 806 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack; 807 // Stores marks with the corresponding oop that we need to preserve during evacuation 808 // failure. 809 OopAndMarkOopStack* _preserved_objs; 810 811 // Preserve the mark of "obj", if necessary, in preparation for its mark 812 // word being overwritten with a self-forwarding-pointer. 813 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 814 815 #ifndef PRODUCT 816 // Support for forcing evacuation failures. Analogous to 817 // PromotionFailureALot for the other collectors. 818 819 // Records whether G1EvacuationFailureALot should be in effect 820 // for the current GC 821 bool _evacuation_failure_alot_for_current_gc; 822 823 // Used to record the GC number for interval checking when 824 // determining whether G1EvaucationFailureALot is in effect 825 // for the current GC. 826 size_t _evacuation_failure_alot_gc_number; 827 828 // Count of the number of evacuations between failures. 829 volatile size_t _evacuation_failure_alot_count; 830 831 // Set whether G1EvacuationFailureALot should be in effect 832 // for the current GC (based upon the type of GC and which 833 // command line flags are set); 834 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 835 bool during_initial_mark, 836 bool during_marking); 837 838 inline void set_evacuation_failure_alot_for_current_gc(); 839 840 // Return true if it's time to cause an evacuation failure. 841 inline bool evacuation_should_fail(); 842 843 // Reset the G1EvacuationFailureALot counters. Should be called at 844 // the end of an evacuation pause in which an evacuation failure occurred. 845 inline void reset_evacuation_should_fail(); 846 #endif // !PRODUCT 847 848 // ("Weak") Reference processing support. 849 // 850 // G1 has 2 instances of the reference processor class. One 851 // (_ref_processor_cm) handles reference object discovery 852 // and subsequent processing during concurrent marking cycles. 853 // 854 // The other (_ref_processor_stw) handles reference object 855 // discovery and processing during full GCs and incremental 856 // evacuation pauses. 857 // 858 // During an incremental pause, reference discovery will be 859 // temporarily disabled for _ref_processor_cm and will be 860 // enabled for _ref_processor_stw. At the end of the evacuation 861 // pause references discovered by _ref_processor_stw will be 862 // processed and discovery will be disabled. The previous 863 // setting for reference object discovery for _ref_processor_cm 864 // will be re-instated. 865 // 866 // At the start of marking: 867 // * Discovery by the CM ref processor is verified to be inactive 868 // and it's discovered lists are empty. 869 // * Discovery by the CM ref processor is then enabled. 870 // 871 // At the end of marking: 872 // * Any references on the CM ref processor's discovered 873 // lists are processed (possibly MT). 874 // 875 // At the start of full GC we: 876 // * Disable discovery by the CM ref processor and 877 // empty CM ref processor's discovered lists 878 // (without processing any entries). 879 // * Verify that the STW ref processor is inactive and it's 880 // discovered lists are empty. 881 // * Temporarily set STW ref processor discovery as single threaded. 882 // * Temporarily clear the STW ref processor's _is_alive_non_header 883 // field. 884 // * Finally enable discovery by the STW ref processor. 885 // 886 // The STW ref processor is used to record any discovered 887 // references during the full GC. 888 // 889 // At the end of a full GC we: 890 // * Enqueue any reference objects discovered by the STW ref processor 891 // that have non-live referents. This has the side-effect of 892 // making the STW ref processor inactive by disabling discovery. 893 // * Verify that the CM ref processor is still inactive 894 // and no references have been placed on it's discovered 895 // lists (also checked as a precondition during initial marking). 896 897 // The (stw) reference processor... 898 ReferenceProcessor* _ref_processor_stw; 899 900 STWGCTimer* _gc_timer_stw; 901 ConcurrentGCTimer* _gc_timer_cm; 902 903 G1OldTracer* _gc_tracer_cm; 904 G1NewTracer* _gc_tracer_stw; 905 906 // During reference object discovery, the _is_alive_non_header 907 // closure (if non-null) is applied to the referent object to 908 // determine whether the referent is live. If so then the 909 // reference object does not need to be 'discovered' and can 910 // be treated as a regular oop. This has the benefit of reducing 911 // the number of 'discovered' reference objects that need to 912 // be processed. 913 // 914 // Instance of the is_alive closure for embedding into the 915 // STW reference processor as the _is_alive_non_header field. 916 // Supplying a value for the _is_alive_non_header field is 917 // optional but doing so prevents unnecessary additions to 918 // the discovered lists during reference discovery. 919 G1STWIsAliveClosure _is_alive_closure_stw; 920 921 // The (concurrent marking) reference processor... 922 ReferenceProcessor* _ref_processor_cm; 923 924 // Instance of the concurrent mark is_alive closure for embedding 925 // into the Concurrent Marking reference processor as the 926 // _is_alive_non_header field. Supplying a value for the 927 // _is_alive_non_header field is optional but doing so prevents 928 // unnecessary additions to the discovered lists during reference 929 // discovery. 930 G1CMIsAliveClosure _is_alive_closure_cm; 931 932 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 933 HeapRegion** _worker_cset_start_region; 934 935 // Time stamp to validate the regions recorded in the cache 936 // used by G1CollectedHeap::start_cset_region_for_worker(). 937 // The heap region entry for a given worker is valid iff 938 // the associated time stamp value matches the current value 939 // of G1CollectedHeap::_gc_time_stamp. 940 uint* _worker_cset_start_region_time_stamp; 941 942 volatile bool _free_regions_coming; 943 944 public: 945 946 void set_refine_cte_cl_concurrency(bool concurrent); 947 948 RefToScanQueue *task_queue(uint i) const; 949 950 uint num_task_queues() const; 951 952 // A set of cards where updates happened during the GC 953 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 954 955 // A DirtyCardQueueSet that is used to hold cards that contain 956 // references into the current collection set. This is used to 957 // update the remembered sets of the regions in the collection 958 // set in the event of an evacuation failure. 959 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 960 { return _into_cset_dirty_card_queue_set; } 961 962 // Create a G1CollectedHeap with the specified policy. 963 // Must call the initialize method afterwards. 964 // May not return if something goes wrong. 965 G1CollectedHeap(G1CollectorPolicy* policy); 966 967 // Initialize the G1CollectedHeap to have the initial and 968 // maximum sizes and remembered and barrier sets 969 // specified by the policy object. 970 jint initialize(); 971 972 virtual void stop(); 973 974 // Return the (conservative) maximum heap alignment for any G1 heap 975 static size_t conservative_max_heap_alignment(); 976 977 // Does operations required after initialization has been done. 978 void post_initialize(); 979 980 // Initialize weak reference processing. 981 void ref_processing_init(); 982 983 virtual Name kind() const { 984 return CollectedHeap::G1CollectedHeap; 985 } 986 987 const G1CollectorState* collector_state() const { return &_collector_state; } 988 G1CollectorState* collector_state() { return &_collector_state; } 989 990 // The current policy object for the collector. 991 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 992 993 virtual CollectorPolicy* collector_policy() const; 994 995 // Adaptive size policy. No such thing for g1. 996 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 997 998 // The rem set and barrier set. 999 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1000 1001 unsigned get_gc_time_stamp() { 1002 return _gc_time_stamp; 1003 } 1004 1005 inline void reset_gc_time_stamp(); 1006 1007 void check_gc_time_stamps() PRODUCT_RETURN; 1008 1009 inline void increment_gc_time_stamp(); 1010 1011 // Reset the given region's GC timestamp. If it's starts humongous, 1012 // also reset the GC timestamp of its corresponding 1013 // continues humongous regions too. 1014 void reset_gc_time_stamps(HeapRegion* hr); 1015 1016 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1017 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1018 1019 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1020 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1021 1022 // The shared block offset table array. 1023 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1024 1025 // Reference Processing accessors 1026 1027 // The STW reference processor.... 1028 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1029 1030 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1031 1032 // The Concurrent Marking reference processor... 1033 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1034 1035 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1036 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1037 1038 virtual size_t capacity() const; 1039 virtual size_t used() const; 1040 // This should be called when we're not holding the heap lock. The 1041 // result might be a bit inaccurate. 1042 size_t used_unlocked() const; 1043 size_t recalculate_used() const; 1044 1045 // These virtual functions do the actual allocation. 1046 // Some heaps may offer a contiguous region for shared non-blocking 1047 // allocation, via inlined code (by exporting the address of the top and 1048 // end fields defining the extent of the contiguous allocation region.) 1049 // But G1CollectedHeap doesn't yet support this. 1050 1051 virtual bool is_maximal_no_gc() const { 1052 return _hrm.available() == 0; 1053 } 1054 1055 // The current number of regions in the heap. 1056 uint num_regions() const { return _hrm.length(); } 1057 1058 // The max number of regions in the heap. 1059 uint max_regions() const { return _hrm.max_length(); } 1060 1061 // The number of regions that are completely free. 1062 uint num_free_regions() const { return _hrm.num_free_regions(); } 1063 1064 MemoryUsage get_auxiliary_data_memory_usage() const { 1065 return _hrm.get_auxiliary_data_memory_usage(); 1066 } 1067 1068 // The number of regions that are not completely free. 1069 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1070 1071 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1072 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1073 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1074 void verify_dirty_young_regions() PRODUCT_RETURN; 1075 1076 #ifndef PRODUCT 1077 // Make sure that the given bitmap has no marked objects in the 1078 // range [from,limit). If it does, print an error message and return 1079 // false. Otherwise, just return true. bitmap_name should be "prev" 1080 // or "next". 1081 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1082 HeapWord* from, HeapWord* limit); 1083 1084 // Verify that the prev / next bitmap range [tams,end) for the given 1085 // region has no marks. Return true if all is well, false if errors 1086 // are detected. 1087 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1088 #endif // PRODUCT 1089 1090 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1091 // the given region do not have any spurious marks. If errors are 1092 // detected, print appropriate error messages and crash. 1093 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1094 1095 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1096 // have any spurious marks. If errors are detected, print 1097 // appropriate error messages and crash. 1098 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1099 1100 // Do sanity check on the contents of the in-cset fast test table. 1101 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1102 1103 // verify_region_sets() performs verification over the region 1104 // lists. It will be compiled in the product code to be used when 1105 // necessary (i.e., during heap verification). 1106 void verify_region_sets(); 1107 1108 // verify_region_sets_optional() is planted in the code for 1109 // list verification in non-product builds (and it can be enabled in 1110 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1111 #if HEAP_REGION_SET_FORCE_VERIFY 1112 void verify_region_sets_optional() { 1113 verify_region_sets(); 1114 } 1115 #else // HEAP_REGION_SET_FORCE_VERIFY 1116 void verify_region_sets_optional() { } 1117 #endif // HEAP_REGION_SET_FORCE_VERIFY 1118 1119 #ifdef ASSERT 1120 bool is_on_master_free_list(HeapRegion* hr) { 1121 return _hrm.is_free(hr); 1122 } 1123 #endif // ASSERT 1124 1125 // Wrapper for the region list operations that can be called from 1126 // methods outside this class. 1127 1128 void secondary_free_list_add(FreeRegionList* list) { 1129 _secondary_free_list.add_ordered(list); 1130 } 1131 1132 void append_secondary_free_list() { 1133 _hrm.insert_list_into_free_list(&_secondary_free_list); 1134 } 1135 1136 void append_secondary_free_list_if_not_empty_with_lock() { 1137 // If the secondary free list looks empty there's no reason to 1138 // take the lock and then try to append it. 1139 if (!_secondary_free_list.is_empty()) { 1140 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1141 append_secondary_free_list(); 1142 } 1143 } 1144 1145 inline void old_set_add(HeapRegion* hr); 1146 inline void old_set_remove(HeapRegion* hr); 1147 1148 size_t non_young_capacity_bytes() { 1149 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1150 } 1151 1152 void set_free_regions_coming(); 1153 void reset_free_regions_coming(); 1154 bool free_regions_coming() { return _free_regions_coming; } 1155 void wait_while_free_regions_coming(); 1156 1157 // Determine whether the given region is one that we are using as an 1158 // old GC alloc region. 1159 bool is_old_gc_alloc_region(HeapRegion* hr); 1160 1161 // Perform a collection of the heap; intended for use in implementing 1162 // "System.gc". This probably implies as full a collection as the 1163 // "CollectedHeap" supports. 1164 virtual void collect(GCCause::Cause cause); 1165 1166 // The same as above but assume that the caller holds the Heap_lock. 1167 void collect_locked(GCCause::Cause cause); 1168 1169 virtual bool copy_allocation_context_stats(const jint* contexts, 1170 jlong* totals, 1171 jbyte* accuracy, 1172 jint len); 1173 1174 // True iff an evacuation has failed in the most-recent collection. 1175 bool evacuation_failed() { return _evacuation_failed; } 1176 1177 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1178 void prepend_to_freelist(FreeRegionList* list); 1179 void decrement_summary_bytes(size_t bytes); 1180 1181 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1182 virtual bool is_in(const void* p) const; 1183 #ifdef ASSERT 1184 // Returns whether p is in one of the available areas of the heap. Slow but 1185 // extensive version. 1186 bool is_in_exact(const void* p) const; 1187 #endif 1188 1189 // Return "TRUE" iff the given object address is within the collection 1190 // set. Slow implementation. 1191 bool obj_in_cs(oop obj); 1192 1193 inline bool is_in_cset(const HeapRegion *hr); 1194 inline bool is_in_cset(oop obj); 1195 1196 inline bool is_in_cset_or_humongous(const oop obj); 1197 1198 private: 1199 // This array is used for a quick test on whether a reference points into 1200 // the collection set or not. Each of the array's elements denotes whether the 1201 // corresponding region is in the collection set or not. 1202 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1203 1204 public: 1205 1206 inline InCSetState in_cset_state(const oop obj); 1207 1208 // Return "TRUE" iff the given object address is in the reserved 1209 // region of g1. 1210 bool is_in_g1_reserved(const void* p) const { 1211 return _hrm.reserved().contains(p); 1212 } 1213 1214 // Returns a MemRegion that corresponds to the space that has been 1215 // reserved for the heap 1216 MemRegion g1_reserved() const { 1217 return _hrm.reserved(); 1218 } 1219 1220 virtual bool is_in_closed_subset(const void* p) const; 1221 1222 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1223 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1224 } 1225 1226 // This resets the card table to all zeros. It is used after 1227 // a collection pause which used the card table to claim cards. 1228 void cleanUpCardTable(); 1229 1230 // Iteration functions. 1231 1232 // Iterate over all objects, calling "cl.do_object" on each. 1233 virtual void object_iterate(ObjectClosure* cl); 1234 1235 virtual void safe_object_iterate(ObjectClosure* cl) { 1236 object_iterate(cl); 1237 } 1238 1239 // Iterate over heap regions, in address order, terminating the 1240 // iteration early if the "doHeapRegion" method returns "true". 1241 void heap_region_iterate(HeapRegionClosure* blk) const; 1242 1243 // Return the region with the given index. It assumes the index is valid. 1244 inline HeapRegion* region_at(uint index) const; 1245 1246 // Calculate the region index of the given address. Given address must be 1247 // within the heap. 1248 inline uint addr_to_region(HeapWord* addr) const; 1249 1250 inline HeapWord* bottom_addr_for_region(uint index) const; 1251 1252 // Iterate over the heap regions in parallel. Assumes that this will be called 1253 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1254 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1255 // to each of the regions, by attempting to claim the region using the 1256 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1257 // region. The concurrent argument should be set to true if iteration is 1258 // performed concurrently, during which no assumptions are made for consistent 1259 // attributes of the heap regions (as they might be modified while iterating). 1260 void heap_region_par_iterate(HeapRegionClosure* cl, 1261 uint worker_id, 1262 HeapRegionClaimer* hrclaimer, 1263 bool concurrent = false) const; 1264 1265 // Clear the cached cset start regions and (more importantly) 1266 // the time stamps. Called when we reset the GC time stamp. 1267 void clear_cset_start_regions(); 1268 1269 // Given the id of a worker, obtain or calculate a suitable 1270 // starting region for iterating over the current collection set. 1271 HeapRegion* start_cset_region_for_worker(uint worker_i); 1272 1273 // Iterate over the regions (if any) in the current collection set. 1274 void collection_set_iterate(HeapRegionClosure* blk); 1275 1276 // As above but starting from region r 1277 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1278 1279 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1280 1281 // Returns the HeapRegion that contains addr. addr must not be NULL. 1282 template <class T> 1283 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1284 1285 // Returns the HeapRegion that contains addr. addr must not be NULL. 1286 // If addr is within a humongous continues region, it returns its humongous start region. 1287 template <class T> 1288 inline HeapRegion* heap_region_containing(const T addr) const; 1289 1290 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1291 // each address in the (reserved) heap is a member of exactly 1292 // one block. The defining characteristic of a block is that it is 1293 // possible to find its size, and thus to progress forward to the next 1294 // block. (Blocks may be of different sizes.) Thus, blocks may 1295 // represent Java objects, or they might be free blocks in a 1296 // free-list-based heap (or subheap), as long as the two kinds are 1297 // distinguishable and the size of each is determinable. 1298 1299 // Returns the address of the start of the "block" that contains the 1300 // address "addr". We say "blocks" instead of "object" since some heaps 1301 // may not pack objects densely; a chunk may either be an object or a 1302 // non-object. 1303 virtual HeapWord* block_start(const void* addr) const; 1304 1305 // Requires "addr" to be the start of a chunk, and returns its size. 1306 // "addr + size" is required to be the start of a new chunk, or the end 1307 // of the active area of the heap. 1308 virtual size_t block_size(const HeapWord* addr) const; 1309 1310 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1311 // the block is an object. 1312 virtual bool block_is_obj(const HeapWord* addr) const; 1313 1314 // Section on thread-local allocation buffers (TLABs) 1315 // See CollectedHeap for semantics. 1316 1317 bool supports_tlab_allocation() const; 1318 size_t tlab_capacity(Thread* ignored) const; 1319 size_t tlab_used(Thread* ignored) const; 1320 size_t max_tlab_size() const; 1321 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1322 1323 // Can a compiler initialize a new object without store barriers? 1324 // This permission only extends from the creation of a new object 1325 // via a TLAB up to the first subsequent safepoint. If such permission 1326 // is granted for this heap type, the compiler promises to call 1327 // defer_store_barrier() below on any slow path allocation of 1328 // a new object for which such initializing store barriers will 1329 // have been elided. G1, like CMS, allows this, but should be 1330 // ready to provide a compensating write barrier as necessary 1331 // if that storage came out of a non-young region. The efficiency 1332 // of this implementation depends crucially on being able to 1333 // answer very efficiently in constant time whether a piece of 1334 // storage in the heap comes from a young region or not. 1335 // See ReduceInitialCardMarks. 1336 virtual bool can_elide_tlab_store_barriers() const { 1337 return true; 1338 } 1339 1340 virtual bool card_mark_must_follow_store() const { 1341 return true; 1342 } 1343 1344 inline bool is_in_young(const oop obj); 1345 1346 virtual bool is_scavengable(const void* addr); 1347 1348 // We don't need barriers for initializing stores to objects 1349 // in the young gen: for the SATB pre-barrier, there is no 1350 // pre-value that needs to be remembered; for the remembered-set 1351 // update logging post-barrier, we don't maintain remembered set 1352 // information for young gen objects. 1353 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1354 1355 // Returns "true" iff the given word_size is "very large". 1356 static bool is_humongous(size_t word_size) { 1357 // Note this has to be strictly greater-than as the TLABs 1358 // are capped at the humongous threshold and we want to 1359 // ensure that we don't try to allocate a TLAB as 1360 // humongous and that we don't allocate a humongous 1361 // object in a TLAB. 1362 return word_size > _humongous_object_threshold_in_words; 1363 } 1364 1365 // Returns the humongous threshold for a specific region size 1366 static size_t humongous_threshold_for(size_t region_size) { 1367 return (region_size / 2); 1368 } 1369 1370 // Update mod union table with the set of dirty cards. 1371 void updateModUnion(); 1372 1373 // Set the mod union bits corresponding to the given memRegion. Note 1374 // that this is always a safe operation, since it doesn't clear any 1375 // bits. 1376 void markModUnionRange(MemRegion mr); 1377 1378 // Print the maximum heap capacity. 1379 virtual size_t max_capacity() const; 1380 1381 virtual jlong millis_since_last_gc(); 1382 1383 1384 // Convenience function to be used in situations where the heap type can be 1385 // asserted to be this type. 1386 static G1CollectedHeap* heap(); 1387 1388 void set_region_short_lived_locked(HeapRegion* hr); 1389 // add appropriate methods for any other surv rate groups 1390 1391 YoungList* young_list() const { return _young_list; } 1392 1393 // debugging 1394 bool check_young_list_well_formed() { 1395 return _young_list->check_list_well_formed(); 1396 } 1397 1398 bool check_young_list_empty(bool check_heap, 1399 bool check_sample = true); 1400 1401 // *** Stuff related to concurrent marking. It's not clear to me that so 1402 // many of these need to be public. 1403 1404 // The functions below are helper functions that a subclass of 1405 // "CollectedHeap" can use in the implementation of its virtual 1406 // functions. 1407 // This performs a concurrent marking of the live objects in a 1408 // bitmap off to the side. 1409 void doConcurrentMark(); 1410 1411 bool isMarkedPrev(oop obj) const; 1412 bool isMarkedNext(oop obj) const; 1413 1414 // Determine if an object is dead, given the object and also 1415 // the region to which the object belongs. An object is dead 1416 // iff a) it was not allocated since the last mark, b) it 1417 // is not marked, and c) it is not in an archive region. 1418 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1419 return 1420 !hr->obj_allocated_since_prev_marking(obj) && 1421 !isMarkedPrev(obj) && 1422 !hr->is_archive(); 1423 } 1424 1425 // This function returns true when an object has been 1426 // around since the previous marking and hasn't yet 1427 // been marked during this marking, and is not in an archive region. 1428 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1429 return 1430 !hr->obj_allocated_since_next_marking(obj) && 1431 !isMarkedNext(obj) && 1432 !hr->is_archive(); 1433 } 1434 1435 // Determine if an object is dead, given only the object itself. 1436 // This will find the region to which the object belongs and 1437 // then call the region version of the same function. 1438 1439 // Added if it is NULL it isn't dead. 1440 1441 inline bool is_obj_dead(const oop obj) const; 1442 1443 inline bool is_obj_ill(const oop obj) const; 1444 1445 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1446 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1447 bool is_marked(oop obj, VerifyOption vo); 1448 const char* top_at_mark_start_str(VerifyOption vo); 1449 1450 ConcurrentMark* concurrent_mark() const { return _cm; } 1451 1452 // Refinement 1453 1454 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1455 1456 // The dirty cards region list is used to record a subset of regions 1457 // whose cards need clearing. The list if populated during the 1458 // remembered set scanning and drained during the card table 1459 // cleanup. Although the methods are reentrant, population/draining 1460 // phases must not overlap. For synchronization purposes the last 1461 // element on the list points to itself. 1462 HeapRegion* _dirty_cards_region_list; 1463 void push_dirty_cards_region(HeapRegion* hr); 1464 HeapRegion* pop_dirty_cards_region(); 1465 1466 // Optimized nmethod scanning support routines 1467 1468 // Register the given nmethod with the G1 heap. 1469 virtual void register_nmethod(nmethod* nm); 1470 1471 // Unregister the given nmethod from the G1 heap. 1472 virtual void unregister_nmethod(nmethod* nm); 1473 1474 // Free up superfluous code root memory. 1475 void purge_code_root_memory(); 1476 1477 // Rebuild the strong code root lists for each region 1478 // after a full GC. 1479 void rebuild_strong_code_roots(); 1480 1481 // Delete entries for dead interned string and clean up unreferenced symbols 1482 // in symbol table, possibly in parallel. 1483 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1484 1485 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1486 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1487 1488 // Redirty logged cards in the refinement queue. 1489 void redirty_logged_cards(); 1490 // Verification 1491 1492 // Perform any cleanup actions necessary before allowing a verification. 1493 virtual void prepare_for_verify(); 1494 1495 // Perform verification. 1496 1497 // vo == UsePrevMarking -> use "prev" marking information, 1498 // vo == UseNextMarking -> use "next" marking information 1499 // vo == UseMarkWord -> use the mark word in the object header 1500 // 1501 // NOTE: Only the "prev" marking information is guaranteed to be 1502 // consistent most of the time, so most calls to this should use 1503 // vo == UsePrevMarking. 1504 // Currently, there is only one case where this is called with 1505 // vo == UseNextMarking, which is to verify the "next" marking 1506 // information at the end of remark. 1507 // Currently there is only one place where this is called with 1508 // vo == UseMarkWord, which is to verify the marking during a 1509 // full GC. 1510 void verify(bool silent, VerifyOption vo); 1511 1512 // Override; it uses the "prev" marking information 1513 virtual void verify(bool silent); 1514 1515 // The methods below are here for convenience and dispatch the 1516 // appropriate method depending on value of the given VerifyOption 1517 // parameter. The values for that parameter, and their meanings, 1518 // are the same as those above. 1519 1520 bool is_obj_dead_cond(const oop obj, 1521 const HeapRegion* hr, 1522 const VerifyOption vo) const; 1523 1524 bool is_obj_dead_cond(const oop obj, 1525 const VerifyOption vo) const; 1526 1527 G1HeapSummary create_g1_heap_summary(); 1528 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1529 1530 // Printing 1531 1532 virtual void print_on(outputStream* st) const; 1533 virtual void print_extended_on(outputStream* st) const; 1534 virtual void print_on_error(outputStream* st) const; 1535 1536 virtual void print_gc_threads_on(outputStream* st) const; 1537 virtual void gc_threads_do(ThreadClosure* tc) const; 1538 1539 // Override 1540 void print_tracing_info() const; 1541 1542 // The following two methods are helpful for debugging RSet issues. 1543 void print_cset_rsets() PRODUCT_RETURN; 1544 void print_all_rsets() PRODUCT_RETURN; 1545 1546 public: 1547 size_t pending_card_num(); 1548 1549 protected: 1550 size_t _max_heap_capacity; 1551 }; 1552 1553 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP