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/g1EvacFailure.hpp" 37 #include "gc/g1/g1EvacStats.hpp" 38 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 39 #include "gc/g1/g1YCTypes.hpp" 40 #include "gc/g1/hSpaceCounters.hpp" 41 #include "gc/g1/heapRegionManager.hpp" 42 #include "gc/g1/heapRegionSet.hpp" 43 #include "gc/g1/youngList.hpp" 44 #include "gc/shared/barrierSet.hpp" 45 #include "gc/shared/collectedHeap.hpp" 46 #include "gc/shared/plab.hpp" 47 #include "memory/memRegion.hpp" 48 #include "utilities/stack.hpp" 49 50 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 51 // It uses the "Garbage First" heap organization and algorithm, which 52 // may combine concurrent marking with parallel, incremental compaction of 53 // heap subsets that will yield large amounts of garbage. 54 55 // Forward declarations 56 class HeapRegion; 57 class HRRSCleanupTask; 58 class GenerationSpec; 59 class OopsInHeapRegionClosure; 60 class G1ParScanThreadState; 61 class G1ParScanThreadStateSet; 62 class G1KlassScanClosure; 63 class G1ParScanThreadState; 64 class ObjectClosure; 65 class SpaceClosure; 66 class CompactibleSpaceClosure; 67 class Space; 68 class G1CollectorPolicy; 69 class G1RemSet; 70 class HeapRegionRemSetIterator; 71 class ConcurrentMark; 72 class ConcurrentMarkThread; 73 class ConcurrentG1Refine; 74 class ConcurrentGCTimer; 75 class GenerationCounters; 76 class STWGCTimer; 77 class G1NewTracer; 78 class G1OldTracer; 79 class EvacuationFailedInfo; 80 class nmethod; 81 class Ticks; 82 class WorkGang; 83 class G1Allocator; 84 class G1ArchiveAllocator; 85 86 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 87 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 88 89 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 90 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 91 92 // The G1 STW is alive closure. 93 // An instance is embedded into the G1CH and used as the 94 // (optional) _is_alive_non_header closure in the STW 95 // reference processor. It is also extensively used during 96 // reference processing during STW evacuation pauses. 97 class G1STWIsAliveClosure: public BoolObjectClosure { 98 G1CollectedHeap* _g1; 99 public: 100 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 101 bool do_object_b(oop p); 102 }; 103 104 class RefineCardTableEntryClosure; 105 106 class G1RegionMappingChangedListener : public G1MappingChangedListener { 107 private: 108 void reset_from_card_cache(uint start_idx, size_t num_regions); 109 public: 110 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 111 }; 112 113 class G1CollectedHeap : public CollectedHeap { 114 friend class VM_CollectForMetadataAllocation; 115 friend class VM_G1CollectForAllocation; 116 friend class VM_G1CollectFull; 117 friend class VM_G1IncCollectionPause; 118 friend class VMStructs; 119 friend class MutatorAllocRegion; 120 friend class G1GCAllocRegion; 121 122 // Closures used in implementation. 123 friend class G1ParScanThreadState; 124 friend class G1ParScanThreadStateSet; 125 friend class G1ParTask; 126 friend class G1PLABAllocator; 127 friend class G1PrepareCompactClosure; 128 129 // Other related classes. 130 friend class HeapRegionClaimer; 131 132 // Testing classes. 133 friend class G1CheckCSetFastTableClosure; 134 135 private: 136 WorkGang* _workers; 137 138 static size_t _humongous_object_threshold_in_words; 139 140 // The secondary free list which contains regions that have been 141 // freed up during the cleanup process. This will be appended to 142 // the master free list when appropriate. 143 FreeRegionList _secondary_free_list; 144 145 // It keeps track of the old regions. 146 HeapRegionSet _old_set; 147 148 // It keeps track of the humongous regions. 149 HeapRegionSet _humongous_set; 150 151 void eagerly_reclaim_humongous_regions(); 152 153 // The number of regions we could create by expansion. 154 uint _expansion_regions; 155 156 // The block offset table for the G1 heap. 157 G1BlockOffsetSharedArray* _bot_shared; 158 159 // Tears down the region sets / lists so that they are empty and the 160 // regions on the heap do not belong to a region set / list. The 161 // only exception is the humongous set which we leave unaltered. If 162 // free_list_only is true, it will only tear down the master free 163 // list. It is called before a Full GC (free_list_only == false) or 164 // before heap shrinking (free_list_only == true). 165 void tear_down_region_sets(bool free_list_only); 166 167 // Rebuilds the region sets / lists so that they are repopulated to 168 // reflect the contents of the heap. The only exception is the 169 // humongous set which was not torn down in the first place. If 170 // free_list_only is true, it will only rebuild the master free 171 // list. It is called after a Full GC (free_list_only == false) or 172 // after heap shrinking (free_list_only == true). 173 void rebuild_region_sets(bool free_list_only); 174 175 // Callback for region mapping changed events. 176 G1RegionMappingChangedListener _listener; 177 178 // The sequence of all heap regions in the heap. 179 HeapRegionManager _hrm; 180 181 // Manages all allocations with regions except humongous object allocations. 182 G1Allocator* _allocator; 183 184 // Outside of GC pauses, the number of bytes used in all regions other 185 // than the current allocation region(s). 186 size_t _summary_bytes_used; 187 188 void increase_used(size_t bytes); 189 void decrease_used(size_t bytes); 190 191 void set_used(size_t bytes); 192 193 // Class that handles archive allocation ranges. 194 G1ArchiveAllocator* _archive_allocator; 195 196 // Statistics for each allocation context 197 AllocationContextStats _allocation_context_stats; 198 199 // GC allocation statistics policy for survivors. 200 G1EvacStats _survivor_evac_stats; 201 202 // GC allocation statistics policy for tenured objects. 203 G1EvacStats _old_evac_stats; 204 205 // It specifies whether we should attempt to expand the heap after a 206 // region allocation failure. If heap expansion fails we set this to 207 // false so that we don't re-attempt the heap expansion (it's likely 208 // that subsequent expansion attempts will also fail if one fails). 209 // Currently, it is only consulted during GC and it's reset at the 210 // start of each GC. 211 bool _expand_heap_after_alloc_failure; 212 213 // Helper for monitoring and management support. 214 G1MonitoringSupport* _g1mm; 215 216 // Records whether the region at the given index is (still) a 217 // candidate for eager reclaim. Only valid for humongous start 218 // regions; other regions have unspecified values. Humongous start 219 // regions are initialized at start of collection pause, with 220 // candidates removed from the set as they are found reachable from 221 // roots or the young generation. 222 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 223 protected: 224 bool default_value() const { return false; } 225 public: 226 void clear() { G1BiasedMappedArray<bool>::clear(); } 227 void set_candidate(uint region, bool value) { 228 set_by_index(region, value); 229 } 230 bool is_candidate(uint region) { 231 return get_by_index(region); 232 } 233 }; 234 235 HumongousReclaimCandidates _humongous_reclaim_candidates; 236 // Stores whether during humongous object registration we found candidate regions. 237 // If not, we can skip a few steps. 238 bool _has_humongous_reclaim_candidates; 239 240 volatile unsigned _gc_time_stamp; 241 242 G1HRPrinter _hr_printer; 243 244 // It decides whether an explicit GC should start a concurrent cycle 245 // instead of doing a STW GC. Currently, a concurrent cycle is 246 // explicitly started if: 247 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 248 // (b) cause == _g1_humongous_allocation 249 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 250 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 251 // (e) cause == _update_allocation_context_stats_inc 252 // (f) cause == _wb_conc_mark 253 bool should_do_concurrent_full_gc(GCCause::Cause cause); 254 255 // indicates whether we are in young or mixed GC mode 256 G1CollectorState _collector_state; 257 258 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 259 // concurrent cycles) we have started. 260 volatile uint _old_marking_cycles_started; 261 262 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 263 // concurrent cycles) we have completed. 264 volatile uint _old_marking_cycles_completed; 265 266 bool _heap_summary_sent; 267 268 // This is a non-product method that is helpful for testing. It is 269 // called at the end of a GC and artificially expands the heap by 270 // allocating a number of dead regions. This way we can induce very 271 // frequent marking cycles and stress the cleanup / concurrent 272 // cleanup code more (as all the regions that will be allocated by 273 // this method will be found dead by the marking cycle). 274 void allocate_dummy_regions() PRODUCT_RETURN; 275 276 // Clear RSets after a compaction. It also resets the GC time stamps. 277 void clear_rsets_post_compaction(); 278 279 // If the HR printer is active, dump the state of the regions in the 280 // heap after a compaction. 281 void print_hrm_post_compaction(); 282 283 // Create a memory mapper for auxiliary data structures of the given size and 284 // translation factor. 285 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 286 size_t size, 287 size_t translation_factor); 288 289 double verify(bool guard, const char* msg); 290 void verify_before_gc(); 291 void verify_after_gc(); 292 293 void log_gc_footer(jlong pause_time_counter); 294 295 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 296 297 void process_weak_jni_handles(); 298 299 // These are macros so that, if the assert fires, we get the correct 300 // line number, file, etc. 301 302 #define heap_locking_asserts_params(_extra_message_) \ 303 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 304 (_extra_message_), \ 305 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 306 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 307 BOOL_TO_STR(Thread::current()->is_VM_thread()) 308 309 #define assert_heap_locked() \ 310 do { \ 311 assert(Heap_lock->owned_by_self(), \ 312 heap_locking_asserts_params("should be holding the Heap_lock")); \ 313 } while (0) 314 315 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 316 do { \ 317 assert(Heap_lock->owned_by_self() || \ 318 (SafepointSynchronize::is_at_safepoint() && \ 319 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 320 heap_locking_asserts_params("should be holding the Heap_lock or " \ 321 "should be at a safepoint")); \ 322 } while (0) 323 324 #define assert_heap_locked_and_not_at_safepoint() \ 325 do { \ 326 assert(Heap_lock->owned_by_self() && \ 327 !SafepointSynchronize::is_at_safepoint(), \ 328 heap_locking_asserts_params("should be holding the Heap_lock and " \ 329 "should not be at a safepoint")); \ 330 } while (0) 331 332 #define assert_heap_not_locked() \ 333 do { \ 334 assert(!Heap_lock->owned_by_self(), \ 335 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 336 } while (0) 337 338 #define assert_heap_not_locked_and_not_at_safepoint() \ 339 do { \ 340 assert(!Heap_lock->owned_by_self() && \ 341 !SafepointSynchronize::is_at_safepoint(), \ 342 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 343 "should not be at a safepoint")); \ 344 } while (0) 345 346 #define assert_at_safepoint(_should_be_vm_thread_) \ 347 do { \ 348 assert(SafepointSynchronize::is_at_safepoint() && \ 349 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 350 heap_locking_asserts_params("should be at a safepoint")); \ 351 } while (0) 352 353 #define assert_not_at_safepoint() \ 354 do { \ 355 assert(!SafepointSynchronize::is_at_safepoint(), \ 356 heap_locking_asserts_params("should not be at a safepoint")); \ 357 } while (0) 358 359 protected: 360 361 // The young region list. 362 YoungList* _young_list; 363 364 // The current policy object for the collector. 365 G1CollectorPolicy* _g1_policy; 366 367 // This is the second level of trying to allocate a new region. If 368 // new_region() didn't find a region on the free_list, this call will 369 // check whether there's anything available on the 370 // secondary_free_list and/or wait for more regions to appear on 371 // that list, if _free_regions_coming is set. 372 HeapRegion* new_region_try_secondary_free_list(bool is_old); 373 374 // Try to allocate a single non-humongous HeapRegion sufficient for 375 // an allocation of the given word_size. If do_expand is true, 376 // attempt to expand the heap if necessary to satisfy the allocation 377 // request. If the region is to be used as an old region or for a 378 // humongous object, set is_old to true. If not, to false. 379 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 380 381 // Initialize a contiguous set of free regions of length num_regions 382 // and starting at index first so that they appear as a single 383 // humongous region. 384 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 385 uint num_regions, 386 size_t word_size, 387 AllocationContext_t context); 388 389 // Attempt to allocate a humongous object of the given size. Return 390 // NULL if unsuccessful. 391 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 392 393 // The following two methods, allocate_new_tlab() and 394 // mem_allocate(), are the two main entry points from the runtime 395 // into the G1's allocation routines. They have the following 396 // assumptions: 397 // 398 // * They should both be called outside safepoints. 399 // 400 // * They should both be called without holding the Heap_lock. 401 // 402 // * All allocation requests for new TLABs should go to 403 // allocate_new_tlab(). 404 // 405 // * All non-TLAB allocation requests should go to mem_allocate(). 406 // 407 // * If either call cannot satisfy the allocation request using the 408 // current allocating region, they will try to get a new one. If 409 // this fails, they will attempt to do an evacuation pause and 410 // retry the allocation. 411 // 412 // * If all allocation attempts fail, even after trying to schedule 413 // an evacuation pause, allocate_new_tlab() will return NULL, 414 // whereas mem_allocate() will attempt a heap expansion and/or 415 // schedule a Full GC. 416 // 417 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 418 // should never be called with word_size being humongous. All 419 // humongous allocation requests should go to mem_allocate() which 420 // will satisfy them with a special path. 421 422 virtual HeapWord* allocate_new_tlab(size_t word_size); 423 424 virtual HeapWord* mem_allocate(size_t word_size, 425 bool* gc_overhead_limit_was_exceeded); 426 427 // The following three methods take a gc_count_before_ret 428 // parameter which is used to return the GC count if the method 429 // returns NULL. Given that we are required to read the GC count 430 // while holding the Heap_lock, and these paths will take the 431 // Heap_lock at some point, it's easier to get them to read the GC 432 // count while holding the Heap_lock before they return NULL instead 433 // of the caller (namely: mem_allocate()) having to also take the 434 // Heap_lock just to read the GC count. 435 436 // First-level mutator allocation attempt: try to allocate out of 437 // the mutator alloc region without taking the Heap_lock. This 438 // should only be used for non-humongous allocations. 439 inline HeapWord* attempt_allocation(size_t word_size, 440 uint* gc_count_before_ret, 441 uint* gclocker_retry_count_ret); 442 443 // Second-level mutator allocation attempt: take the Heap_lock and 444 // retry the allocation attempt, potentially scheduling a GC 445 // pause. This should only be used for non-humongous allocations. 446 HeapWord* attempt_allocation_slow(size_t word_size, 447 AllocationContext_t context, 448 uint* gc_count_before_ret, 449 uint* gclocker_retry_count_ret); 450 451 // Takes the Heap_lock and attempts a humongous allocation. It can 452 // potentially schedule a GC pause. 453 HeapWord* attempt_allocation_humongous(size_t word_size, 454 uint* gc_count_before_ret, 455 uint* gclocker_retry_count_ret); 456 457 // Allocation attempt that should be called during safepoints (e.g., 458 // at the end of a successful GC). expect_null_mutator_alloc_region 459 // specifies whether the mutator alloc region is expected to be NULL 460 // or not. 461 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 462 AllocationContext_t context, 463 bool expect_null_mutator_alloc_region); 464 465 // These methods are the "callbacks" from the G1AllocRegion class. 466 467 // For mutator alloc regions. 468 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 469 void retire_mutator_alloc_region(HeapRegion* alloc_region, 470 size_t allocated_bytes); 471 472 // For GC alloc regions. 473 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 474 InCSetState dest); 475 void retire_gc_alloc_region(HeapRegion* alloc_region, 476 size_t allocated_bytes, InCSetState dest); 477 478 // - if explicit_gc is true, the GC is for a System.gc() etc, 479 // otherwise it's for a failed allocation. 480 // - if clear_all_soft_refs is true, all soft references should be 481 // cleared during the GC. 482 // - it returns false if it is unable to do the collection due to the 483 // GC locker being active, true otherwise. 484 bool do_full_collection(bool explicit_gc, 485 bool clear_all_soft_refs); 486 487 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 488 virtual void do_full_collection(bool clear_all_soft_refs); 489 490 // Resize the heap if necessary after a full collection. 491 void resize_if_necessary_after_full_collection(); 492 493 // Callback from VM_G1CollectForAllocation operation. 494 // This function does everything necessary/possible to satisfy a 495 // failed allocation request (including collection, expansion, etc.) 496 HeapWord* satisfy_failed_allocation(size_t word_size, 497 AllocationContext_t context, 498 bool* succeeded); 499 private: 500 // Helper method for satisfy_failed_allocation() 501 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 502 AllocationContext_t context, 503 bool do_gc, 504 bool clear_all_soft_refs, 505 bool expect_null_mutator_alloc_region, 506 bool* gc_succeeded); 507 508 protected: 509 // Attempting to expand the heap sufficiently 510 // to support an allocation of the given "word_size". If 511 // successful, perform the allocation and return the address of the 512 // allocated block, or else "NULL". 513 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 514 515 // Process any reference objects discovered during 516 // an incremental evacuation pause. 517 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 518 519 // Enqueue any remaining discovered references 520 // after processing. 521 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 522 523 public: 524 WorkGang* workers() const { return _workers; } 525 526 G1Allocator* allocator() { 527 return _allocator; 528 } 529 530 G1MonitoringSupport* g1mm() { 531 assert(_g1mm != NULL, "should have been initialized"); 532 return _g1mm; 533 } 534 535 // Expand the garbage-first heap by at least the given size (in bytes!). 536 // Returns true if the heap was expanded by the requested amount; 537 // false otherwise. 538 // (Rounds up to a HeapRegion boundary.) 539 bool expand(size_t expand_bytes, double* expand_time_ms = NULL); 540 541 // Returns the PLAB statistics for a given destination. 542 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 543 544 // Determines PLAB size for a given destination. 545 inline size_t desired_plab_sz(InCSetState dest); 546 547 inline AllocationContextStats& allocation_context_stats(); 548 549 // Do anything common to GC's. 550 void gc_prologue(bool full); 551 void gc_epilogue(bool full); 552 553 // Modify the reclaim candidate set and test for presence. 554 // These are only valid for starts_humongous regions. 555 inline void set_humongous_reclaim_candidate(uint region, bool value); 556 inline bool is_humongous_reclaim_candidate(uint region); 557 558 // Remove from the reclaim candidate set. Also remove from the 559 // collection set so that later encounters avoid the slow path. 560 inline void set_humongous_is_live(oop obj); 561 562 // Register the given region to be part of the collection set. 563 inline void register_humongous_region_with_cset(uint index); 564 // Register regions with humongous objects (actually on the start region) in 565 // the in_cset_fast_test table. 566 void register_humongous_regions_with_cset(); 567 // We register a region with the fast "in collection set" test. We 568 // simply set to true the array slot corresponding to this region. 569 void register_young_region_with_cset(HeapRegion* r) { 570 _in_cset_fast_test.set_in_young(r->hrm_index()); 571 } 572 void register_old_region_with_cset(HeapRegion* r) { 573 _in_cset_fast_test.set_in_old(r->hrm_index()); 574 } 575 inline void register_ext_region_with_cset(HeapRegion* r) { 576 _in_cset_fast_test.set_ext(r->hrm_index()); 577 } 578 void clear_in_cset(const HeapRegion* hr) { 579 _in_cset_fast_test.clear(hr); 580 } 581 582 void clear_cset_fast_test() { 583 _in_cset_fast_test.clear(); 584 } 585 586 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 587 588 // This is called at the start of either a concurrent cycle or a Full 589 // GC to update the number of old marking cycles started. 590 void increment_old_marking_cycles_started(); 591 592 // This is called at the end of either a concurrent cycle or a Full 593 // GC to update the number of old marking cycles completed. Those two 594 // can happen in a nested fashion, i.e., we start a concurrent 595 // cycle, a Full GC happens half-way through it which ends first, 596 // and then the cycle notices that a Full GC happened and ends 597 // too. The concurrent parameter is a boolean to help us do a bit 598 // tighter consistency checking in the method. If concurrent is 599 // false, the caller is the inner caller in the nesting (i.e., the 600 // Full GC). If concurrent is true, the caller is the outer caller 601 // in this nesting (i.e., the concurrent cycle). Further nesting is 602 // not currently supported. The end of this call also notifies 603 // the FullGCCount_lock in case a Java thread is waiting for a full 604 // GC to happen (e.g., it called System.gc() with 605 // +ExplicitGCInvokesConcurrent). 606 void increment_old_marking_cycles_completed(bool concurrent); 607 608 uint old_marking_cycles_completed() { 609 return _old_marking_cycles_completed; 610 } 611 612 void register_concurrent_cycle_start(const Ticks& start_time); 613 void register_concurrent_cycle_end(); 614 void trace_heap_after_concurrent_cycle(); 615 616 G1HRPrinter* hr_printer() { return &_hr_printer; } 617 618 // Allocates a new heap region instance. 619 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 620 621 // Allocate the highest free region in the reserved heap. This will commit 622 // regions as necessary. 623 HeapRegion* alloc_highest_free_region(); 624 625 // Frees a non-humongous region by initializing its contents and 626 // adding it to the free list that's passed as a parameter (this is 627 // usually a local list which will be appended to the master free 628 // list later). The used bytes of freed regions are accumulated in 629 // pre_used. If par is true, the region's RSet will not be freed 630 // up. The assumption is that this will be done later. 631 // The locked parameter indicates if the caller has already taken 632 // care of proper synchronization. This may allow some optimizations. 633 void free_region(HeapRegion* hr, 634 FreeRegionList* free_list, 635 bool par, 636 bool locked = false); 637 638 // It dirties the cards that cover the block so that the post 639 // write barrier never queues anything when updating objects on this 640 // block. It is assumed (and in fact we assert) that the block 641 // belongs to a young region. 642 inline void dirty_young_block(HeapWord* start, size_t word_size); 643 644 // Frees a humongous region by collapsing it into individual regions 645 // and calling free_region() for each of them. The freed regions 646 // will be added to the free list that's passed as a parameter (this 647 // is usually a local list which will be appended to the master free 648 // list later). The used bytes of freed regions are accumulated in 649 // pre_used. If par is true, the region's RSet will not be freed 650 // up. The assumption is that this will be done later. 651 void free_humongous_region(HeapRegion* hr, 652 FreeRegionList* free_list, 653 bool par); 654 655 // Facility for allocating in 'archive' regions in high heap memory and 656 // recording the allocated ranges. These should all be called from the 657 // VM thread at safepoints, without the heap lock held. They can be used 658 // to create and archive a set of heap regions which can be mapped at the 659 // same fixed addresses in a subsequent JVM invocation. 660 void begin_archive_alloc_range(); 661 662 // Check if the requested size would be too large for an archive allocation. 663 bool is_archive_alloc_too_large(size_t word_size); 664 665 // Allocate memory of the requested size from the archive region. This will 666 // return NULL if the size is too large or if no memory is available. It 667 // does not trigger a garbage collection. 668 HeapWord* archive_mem_allocate(size_t word_size); 669 670 // Optionally aligns the end address and returns the allocated ranges in 671 // an array of MemRegions in order of ascending addresses. 672 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 673 size_t end_alignment_in_bytes = 0); 674 675 // Facility for allocating a fixed range within the heap and marking 676 // the containing regions as 'archive'. For use at JVM init time, when the 677 // caller may mmap archived heap data at the specified range(s). 678 // Verify that the MemRegions specified in the argument array are within the 679 // reserved heap. 680 bool check_archive_addresses(MemRegion* range, size_t count); 681 682 // Commit the appropriate G1 regions containing the specified MemRegions 683 // and mark them as 'archive' regions. The regions in the array must be 684 // non-overlapping and in order of ascending address. 685 bool alloc_archive_regions(MemRegion* range, size_t count); 686 687 // Insert any required filler objects in the G1 regions around the specified 688 // ranges to make the regions parseable. This must be called after 689 // alloc_archive_regions, and after class loading has occurred. 690 void fill_archive_regions(MemRegion* range, size_t count); 691 692 // For each of the specified MemRegions, uncommit the containing G1 regions 693 // which had been allocated by alloc_archive_regions. This should be called 694 // rather than fill_archive_regions at JVM init time if the archive file 695 // mapping failed, with the same non-overlapping and sorted MemRegion array. 696 void dealloc_archive_regions(MemRegion* range, size_t count); 697 698 protected: 699 700 // Shrink the garbage-first heap by at most the given size (in bytes!). 701 // (Rounds down to a HeapRegion boundary.) 702 virtual void shrink(size_t expand_bytes); 703 void shrink_helper(size_t expand_bytes); 704 705 #if TASKQUEUE_STATS 706 static void print_taskqueue_stats_hdr(outputStream* const st); 707 void print_taskqueue_stats() const; 708 void reset_taskqueue_stats(); 709 #endif // TASKQUEUE_STATS 710 711 // Schedule the VM operation that will do an evacuation pause to 712 // satisfy an allocation request of word_size. *succeeded will 713 // return whether the VM operation was successful (it did do an 714 // evacuation pause) or not (another thread beat us to it or the GC 715 // locker was active). Given that we should not be holding the 716 // Heap_lock when we enter this method, we will pass the 717 // gc_count_before (i.e., total_collections()) as a parameter since 718 // it has to be read while holding the Heap_lock. Currently, both 719 // methods that call do_collection_pause() release the Heap_lock 720 // before the call, so it's easy to read gc_count_before just before. 721 HeapWord* do_collection_pause(size_t word_size, 722 uint gc_count_before, 723 bool* succeeded, 724 GCCause::Cause gc_cause); 725 726 void wait_for_root_region_scanning(); 727 728 // The guts of the incremental collection pause, executed by the vm 729 // thread. It returns false if it is unable to do the collection due 730 // to the GC locker being active, true otherwise 731 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 732 733 // Actually do the work of evacuating the collection set. 734 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 735 736 void pre_evacuate_collection_set(); 737 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 738 739 // Print the header for the per-thread termination statistics. 740 static void print_termination_stats_hdr(); 741 // Print actual per-thread termination statistics. 742 void print_termination_stats(uint worker_id, 743 double elapsed_ms, 744 double strong_roots_ms, 745 double term_ms, 746 size_t term_attempts, 747 size_t alloc_buffer_waste, 748 size_t undo_waste) const; 749 // Update object copying statistics. 750 void record_obj_copy_mem_stats(); 751 752 // The g1 remembered set of the heap. 753 G1RemSet* _g1_rem_set; 754 755 // A set of cards that cover the objects for which the Rsets should be updated 756 // concurrently after the collection. 757 DirtyCardQueueSet _dirty_card_queue_set; 758 759 // The closure used to refine a single card. 760 RefineCardTableEntryClosure* _refine_cte_cl; 761 762 // After a collection pause, make the regions in the CS into free 763 // regions. 764 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 765 766 // Abandon the current collection set without recording policy 767 // statistics or updating free lists. 768 void abandon_collection_set(HeapRegion* cs_head); 769 770 // The concurrent marker (and the thread it runs in.) 771 ConcurrentMark* _cm; 772 ConcurrentMarkThread* _cmThread; 773 774 // The concurrent refiner. 775 ConcurrentG1Refine* _cg1r; 776 777 // The parallel task queues 778 RefToScanQueueSet *_task_queues; 779 780 // True iff a evacuation has failed in the current collection. 781 bool _evacuation_failed; 782 783 EvacuationFailedInfo* _evacuation_failed_info_array; 784 785 // Failed evacuations cause some logical from-space objects to have 786 // forwarding pointers to themselves. Reset them. 787 void remove_self_forwarding_pointers(); 788 789 // Restore the preserved mark words for objects with self-forwarding pointers. 790 void restore_preserved_marks(); 791 792 // Restore the objects in the regions in the collection set after an 793 // evacuation failure. 794 void restore_after_evac_failure(); 795 796 // Stores marks with the corresponding oop that we need to preserve during evacuation 797 // failure. 798 OopAndMarkOopStack* _preserved_objs; 799 800 // Preserve the mark of "obj", if necessary, in preparation for its mark 801 // word being overwritten with a self-forwarding-pointer. 802 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 803 804 #ifndef PRODUCT 805 // Support for forcing evacuation failures. Analogous to 806 // PromotionFailureALot for the other collectors. 807 808 // Records whether G1EvacuationFailureALot should be in effect 809 // for the current GC 810 bool _evacuation_failure_alot_for_current_gc; 811 812 // Used to record the GC number for interval checking when 813 // determining whether G1EvaucationFailureALot is in effect 814 // for the current GC. 815 size_t _evacuation_failure_alot_gc_number; 816 817 // Count of the number of evacuations between failures. 818 volatile size_t _evacuation_failure_alot_count; 819 820 // Set whether G1EvacuationFailureALot should be in effect 821 // for the current GC (based upon the type of GC and which 822 // command line flags are set); 823 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 824 bool during_initial_mark, 825 bool during_marking); 826 827 inline void set_evacuation_failure_alot_for_current_gc(); 828 829 // Return true if it's time to cause an evacuation failure. 830 inline bool evacuation_should_fail(); 831 832 // Reset the G1EvacuationFailureALot counters. Should be called at 833 // the end of an evacuation pause in which an evacuation failure occurred. 834 inline void reset_evacuation_should_fail(); 835 #endif // !PRODUCT 836 837 // ("Weak") Reference processing support. 838 // 839 // G1 has 2 instances of the reference processor class. One 840 // (_ref_processor_cm) handles reference object discovery 841 // and subsequent processing during concurrent marking cycles. 842 // 843 // The other (_ref_processor_stw) handles reference object 844 // discovery and processing during full GCs and incremental 845 // evacuation pauses. 846 // 847 // During an incremental pause, reference discovery will be 848 // temporarily disabled for _ref_processor_cm and will be 849 // enabled for _ref_processor_stw. At the end of the evacuation 850 // pause references discovered by _ref_processor_stw will be 851 // processed and discovery will be disabled. The previous 852 // setting for reference object discovery for _ref_processor_cm 853 // will be re-instated. 854 // 855 // At the start of marking: 856 // * Discovery by the CM ref processor is verified to be inactive 857 // and it's discovered lists are empty. 858 // * Discovery by the CM ref processor is then enabled. 859 // 860 // At the end of marking: 861 // * Any references on the CM ref processor's discovered 862 // lists are processed (possibly MT). 863 // 864 // At the start of full GC we: 865 // * Disable discovery by the CM ref processor and 866 // empty CM ref processor's discovered lists 867 // (without processing any entries). 868 // * Verify that the STW ref processor is inactive and it's 869 // discovered lists are empty. 870 // * Temporarily set STW ref processor discovery as single threaded. 871 // * Temporarily clear the STW ref processor's _is_alive_non_header 872 // field. 873 // * Finally enable discovery by the STW ref processor. 874 // 875 // The STW ref processor is used to record any discovered 876 // references during the full GC. 877 // 878 // At the end of a full GC we: 879 // * Enqueue any reference objects discovered by the STW ref processor 880 // that have non-live referents. This has the side-effect of 881 // making the STW ref processor inactive by disabling discovery. 882 // * Verify that the CM ref processor is still inactive 883 // and no references have been placed on it's discovered 884 // lists (also checked as a precondition during initial marking). 885 886 // The (stw) reference processor... 887 ReferenceProcessor* _ref_processor_stw; 888 889 STWGCTimer* _gc_timer_stw; 890 ConcurrentGCTimer* _gc_timer_cm; 891 892 G1OldTracer* _gc_tracer_cm; 893 G1NewTracer* _gc_tracer_stw; 894 895 // During reference object discovery, the _is_alive_non_header 896 // closure (if non-null) is applied to the referent object to 897 // determine whether the referent is live. If so then the 898 // reference object does not need to be 'discovered' and can 899 // be treated as a regular oop. This has the benefit of reducing 900 // the number of 'discovered' reference objects that need to 901 // be processed. 902 // 903 // Instance of the is_alive closure for embedding into the 904 // STW reference processor as the _is_alive_non_header field. 905 // Supplying a value for the _is_alive_non_header field is 906 // optional but doing so prevents unnecessary additions to 907 // the discovered lists during reference discovery. 908 G1STWIsAliveClosure _is_alive_closure_stw; 909 910 // The (concurrent marking) reference processor... 911 ReferenceProcessor* _ref_processor_cm; 912 913 // Instance of the concurrent mark is_alive closure for embedding 914 // into the Concurrent Marking reference processor as the 915 // _is_alive_non_header field. Supplying a value for the 916 // _is_alive_non_header field is optional but doing so prevents 917 // unnecessary additions to the discovered lists during reference 918 // discovery. 919 G1CMIsAliveClosure _is_alive_closure_cm; 920 921 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 922 HeapRegion** _worker_cset_start_region; 923 924 // Time stamp to validate the regions recorded in the cache 925 // used by G1CollectedHeap::start_cset_region_for_worker(). 926 // The heap region entry for a given worker is valid iff 927 // the associated time stamp value matches the current value 928 // of G1CollectedHeap::_gc_time_stamp. 929 uint* _worker_cset_start_region_time_stamp; 930 931 volatile bool _free_regions_coming; 932 933 public: 934 935 void set_refine_cte_cl_concurrency(bool concurrent); 936 937 RefToScanQueue *task_queue(uint i) const; 938 939 uint num_task_queues() const; 940 941 // A set of cards where updates happened during the GC 942 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 943 944 // Create a G1CollectedHeap with the specified policy. 945 // Must call the initialize method afterwards. 946 // May not return if something goes wrong. 947 G1CollectedHeap(G1CollectorPolicy* policy); 948 949 // Initialize the G1CollectedHeap to have the initial and 950 // maximum sizes and remembered and barrier sets 951 // specified by the policy object. 952 jint initialize(); 953 954 virtual void stop(); 955 956 // Return the (conservative) maximum heap alignment for any G1 heap 957 static size_t conservative_max_heap_alignment(); 958 959 // Does operations required after initialization has been done. 960 void post_initialize(); 961 962 // Initialize weak reference processing. 963 void ref_processing_init(); 964 965 virtual Name kind() const { 966 return CollectedHeap::G1CollectedHeap; 967 } 968 969 virtual const char* name() const { 970 return "G1"; 971 } 972 973 const G1CollectorState* collector_state() const { return &_collector_state; } 974 G1CollectorState* collector_state() { return &_collector_state; } 975 976 // The current policy object for the collector. 977 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 978 979 virtual CollectorPolicy* collector_policy() const; 980 981 // Adaptive size policy. No such thing for g1. 982 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 983 984 // The rem set and barrier set. 985 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 986 987 unsigned get_gc_time_stamp() { 988 return _gc_time_stamp; 989 } 990 991 inline void reset_gc_time_stamp(); 992 993 void check_gc_time_stamps() PRODUCT_RETURN; 994 995 inline void increment_gc_time_stamp(); 996 997 // Reset the given region's GC timestamp. If it's starts humongous, 998 // also reset the GC timestamp of its corresponding 999 // continues humongous regions too. 1000 void reset_gc_time_stamps(HeapRegion* hr); 1001 1002 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1003 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1004 1005 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1006 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1007 1008 // The shared block offset table array. 1009 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1010 1011 // Reference Processing accessors 1012 1013 // The STW reference processor.... 1014 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1015 1016 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1017 1018 // The Concurrent Marking reference processor... 1019 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1020 1021 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1022 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1023 1024 virtual size_t capacity() const; 1025 virtual size_t used() const; 1026 // This should be called when we're not holding the heap lock. The 1027 // result might be a bit inaccurate. 1028 size_t used_unlocked() const; 1029 size_t recalculate_used() const; 1030 1031 // These virtual functions do the actual allocation. 1032 // Some heaps may offer a contiguous region for shared non-blocking 1033 // allocation, via inlined code (by exporting the address of the top and 1034 // end fields defining the extent of the contiguous allocation region.) 1035 // But G1CollectedHeap doesn't yet support this. 1036 1037 virtual bool is_maximal_no_gc() const { 1038 return _hrm.available() == 0; 1039 } 1040 1041 // The current number of regions in the heap. 1042 uint num_regions() const { return _hrm.length(); } 1043 1044 // The max number of regions in the heap. 1045 uint max_regions() const { return _hrm.max_length(); } 1046 1047 // The number of regions that are completely free. 1048 uint num_free_regions() const { return _hrm.num_free_regions(); } 1049 1050 MemoryUsage get_auxiliary_data_memory_usage() const { 1051 return _hrm.get_auxiliary_data_memory_usage(); 1052 } 1053 1054 // The number of regions that are not completely free. 1055 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1056 1057 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1058 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1059 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1060 void verify_dirty_young_regions() PRODUCT_RETURN; 1061 1062 #ifndef PRODUCT 1063 // Make sure that the given bitmap has no marked objects in the 1064 // range [from,limit). If it does, print an error message and return 1065 // false. Otherwise, just return true. bitmap_name should be "prev" 1066 // or "next". 1067 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1068 HeapWord* from, HeapWord* limit); 1069 1070 // Verify that the prev / next bitmap range [tams,end) for the given 1071 // region has no marks. Return true if all is well, false if errors 1072 // are detected. 1073 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1074 #endif // PRODUCT 1075 1076 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1077 // the given region do not have any spurious marks. If errors are 1078 // detected, print appropriate error messages and crash. 1079 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1080 1081 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1082 // have any spurious marks. If errors are detected, print 1083 // appropriate error messages and crash. 1084 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1085 1086 // Do sanity check on the contents of the in-cset fast test table. 1087 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1088 1089 // verify_region_sets() performs verification over the region 1090 // lists. It will be compiled in the product code to be used when 1091 // necessary (i.e., during heap verification). 1092 void verify_region_sets(); 1093 1094 // verify_region_sets_optional() is planted in the code for 1095 // list verification in non-product builds (and it can be enabled in 1096 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1097 #if HEAP_REGION_SET_FORCE_VERIFY 1098 void verify_region_sets_optional() { 1099 verify_region_sets(); 1100 } 1101 #else // HEAP_REGION_SET_FORCE_VERIFY 1102 void verify_region_sets_optional() { } 1103 #endif // HEAP_REGION_SET_FORCE_VERIFY 1104 1105 #ifdef ASSERT 1106 bool is_on_master_free_list(HeapRegion* hr) { 1107 return _hrm.is_free(hr); 1108 } 1109 #endif // ASSERT 1110 1111 // Wrapper for the region list operations that can be called from 1112 // methods outside this class. 1113 1114 void secondary_free_list_add(FreeRegionList* list) { 1115 _secondary_free_list.add_ordered(list); 1116 } 1117 1118 void append_secondary_free_list() { 1119 _hrm.insert_list_into_free_list(&_secondary_free_list); 1120 } 1121 1122 void append_secondary_free_list_if_not_empty_with_lock() { 1123 // If the secondary free list looks empty there's no reason to 1124 // take the lock and then try to append it. 1125 if (!_secondary_free_list.is_empty()) { 1126 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1127 append_secondary_free_list(); 1128 } 1129 } 1130 1131 inline void old_set_add(HeapRegion* hr); 1132 inline void old_set_remove(HeapRegion* hr); 1133 1134 size_t non_young_capacity_bytes() { 1135 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1136 } 1137 1138 void set_free_regions_coming(); 1139 void reset_free_regions_coming(); 1140 bool free_regions_coming() { return _free_regions_coming; } 1141 void wait_while_free_regions_coming(); 1142 1143 // Determine whether the given region is one that we are using as an 1144 // old GC alloc region. 1145 bool is_old_gc_alloc_region(HeapRegion* hr); 1146 1147 // Perform a collection of the heap; intended for use in implementing 1148 // "System.gc". This probably implies as full a collection as the 1149 // "CollectedHeap" supports. 1150 virtual void collect(GCCause::Cause cause); 1151 1152 virtual bool copy_allocation_context_stats(const jint* contexts, 1153 jlong* totals, 1154 jbyte* accuracy, 1155 jint len); 1156 1157 // True iff an evacuation has failed in the most-recent collection. 1158 bool evacuation_failed() { return _evacuation_failed; } 1159 1160 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1161 void prepend_to_freelist(FreeRegionList* list); 1162 void decrement_summary_bytes(size_t bytes); 1163 1164 virtual bool is_in(const void* p) const; 1165 #ifdef ASSERT 1166 // Returns whether p is in one of the available areas of the heap. Slow but 1167 // extensive version. 1168 bool is_in_exact(const void* p) const; 1169 #endif 1170 1171 // Return "TRUE" iff the given object address is within the collection 1172 // set. Slow implementation. 1173 bool obj_in_cs(oop obj); 1174 1175 inline bool is_in_cset(const HeapRegion *hr); 1176 inline bool is_in_cset(oop obj); 1177 1178 inline bool is_in_cset_or_humongous(const oop obj); 1179 1180 private: 1181 // This array is used for a quick test on whether a reference points into 1182 // the collection set or not. Each of the array's elements denotes whether the 1183 // corresponding region is in the collection set or not. 1184 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1185 1186 public: 1187 1188 inline InCSetState in_cset_state(const oop obj); 1189 1190 // Return "TRUE" iff the given object address is in the reserved 1191 // region of g1. 1192 bool is_in_g1_reserved(const void* p) const { 1193 return _hrm.reserved().contains(p); 1194 } 1195 1196 // Returns a MemRegion that corresponds to the space that has been 1197 // reserved for the heap 1198 MemRegion g1_reserved() const { 1199 return _hrm.reserved(); 1200 } 1201 1202 virtual bool is_in_closed_subset(const void* p) const; 1203 1204 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1205 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1206 } 1207 1208 // This resets the card table to all zeros. It is used after 1209 // a collection pause which used the card table to claim cards. 1210 void cleanUpCardTable(); 1211 1212 // Iteration functions. 1213 1214 // Iterate over all objects, calling "cl.do_object" on each. 1215 virtual void object_iterate(ObjectClosure* cl); 1216 1217 virtual void safe_object_iterate(ObjectClosure* cl) { 1218 object_iterate(cl); 1219 } 1220 1221 // Iterate over heap regions, in address order, terminating the 1222 // iteration early if the "doHeapRegion" method returns "true". 1223 void heap_region_iterate(HeapRegionClosure* blk) const; 1224 1225 // Return the region with the given index. It assumes the index is valid. 1226 inline HeapRegion* region_at(uint index) const; 1227 1228 // Return the next region (by index) that is part of the same 1229 // humongous object that hr is part of. 1230 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1231 1232 // Calculate the region index of the given address. Given address must be 1233 // within the heap. 1234 inline uint addr_to_region(HeapWord* addr) const; 1235 1236 inline HeapWord* bottom_addr_for_region(uint index) const; 1237 1238 // Iterate over the heap regions in parallel. Assumes that this will be called 1239 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1240 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1241 // to each of the regions, by attempting to claim the region using the 1242 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1243 // region. The concurrent argument should be set to true if iteration is 1244 // performed concurrently, during which no assumptions are made for consistent 1245 // attributes of the heap regions (as they might be modified while iterating). 1246 void heap_region_par_iterate(HeapRegionClosure* cl, 1247 uint worker_id, 1248 HeapRegionClaimer* hrclaimer, 1249 bool concurrent = false) const; 1250 1251 // Clear the cached cset start regions and (more importantly) 1252 // the time stamps. Called when we reset the GC time stamp. 1253 void clear_cset_start_regions(); 1254 1255 // Given the id of a worker, obtain or calculate a suitable 1256 // starting region for iterating over the current collection set. 1257 HeapRegion* start_cset_region_for_worker(uint worker_i); 1258 1259 // Iterate over the regions (if any) in the current collection set. 1260 void collection_set_iterate(HeapRegionClosure* blk); 1261 1262 // As above but starting from region r 1263 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1264 1265 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1266 1267 // Returns the HeapRegion that contains addr. addr must not be NULL. 1268 template <class T> 1269 inline HeapRegion* heap_region_containing(const T addr) const; 1270 1271 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1272 // each address in the (reserved) heap is a member of exactly 1273 // one block. The defining characteristic of a block is that it is 1274 // possible to find its size, and thus to progress forward to the next 1275 // block. (Blocks may be of different sizes.) Thus, blocks may 1276 // represent Java objects, or they might be free blocks in a 1277 // free-list-based heap (or subheap), as long as the two kinds are 1278 // distinguishable and the size of each is determinable. 1279 1280 // Returns the address of the start of the "block" that contains the 1281 // address "addr". We say "blocks" instead of "object" since some heaps 1282 // may not pack objects densely; a chunk may either be an object or a 1283 // non-object. 1284 virtual HeapWord* block_start(const void* addr) const; 1285 1286 // Requires "addr" to be the start of a chunk, and returns its size. 1287 // "addr + size" is required to be the start of a new chunk, or the end 1288 // of the active area of the heap. 1289 virtual size_t block_size(const HeapWord* addr) const; 1290 1291 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1292 // the block is an object. 1293 virtual bool block_is_obj(const HeapWord* addr) const; 1294 1295 // Section on thread-local allocation buffers (TLABs) 1296 // See CollectedHeap for semantics. 1297 1298 bool supports_tlab_allocation() const; 1299 size_t tlab_capacity(Thread* ignored) const; 1300 size_t tlab_used(Thread* ignored) const; 1301 size_t max_tlab_size() const; 1302 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1303 1304 // Can a compiler initialize a new object without store barriers? 1305 // This permission only extends from the creation of a new object 1306 // via a TLAB up to the first subsequent safepoint. If such permission 1307 // is granted for this heap type, the compiler promises to call 1308 // defer_store_barrier() below on any slow path allocation of 1309 // a new object for which such initializing store barriers will 1310 // have been elided. G1, like CMS, allows this, but should be 1311 // ready to provide a compensating write barrier as necessary 1312 // if that storage came out of a non-young region. The efficiency 1313 // of this implementation depends crucially on being able to 1314 // answer very efficiently in constant time whether a piece of 1315 // storage in the heap comes from a young region or not. 1316 // See ReduceInitialCardMarks. 1317 virtual bool can_elide_tlab_store_barriers() const { 1318 return true; 1319 } 1320 1321 virtual bool card_mark_must_follow_store() const { 1322 return true; 1323 } 1324 1325 inline bool is_in_young(const oop obj); 1326 1327 virtual bool is_scavengable(const void* addr); 1328 1329 // We don't need barriers for initializing stores to objects 1330 // in the young gen: for the SATB pre-barrier, there is no 1331 // pre-value that needs to be remembered; for the remembered-set 1332 // update logging post-barrier, we don't maintain remembered set 1333 // information for young gen objects. 1334 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1335 1336 // Returns "true" iff the given word_size is "very large". 1337 static bool is_humongous(size_t word_size) { 1338 // Note this has to be strictly greater-than as the TLABs 1339 // are capped at the humongous threshold and we want to 1340 // ensure that we don't try to allocate a TLAB as 1341 // humongous and that we don't allocate a humongous 1342 // object in a TLAB. 1343 return word_size > _humongous_object_threshold_in_words; 1344 } 1345 1346 // Returns the humongous threshold for a specific region size 1347 static size_t humongous_threshold_for(size_t region_size) { 1348 return (region_size / 2); 1349 } 1350 1351 // Returns the number of regions the humongous object of the given word size 1352 // requires. 1353 static size_t humongous_obj_size_in_regions(size_t word_size); 1354 1355 // Print the maximum heap capacity. 1356 virtual size_t max_capacity() const; 1357 1358 virtual jlong millis_since_last_gc(); 1359 1360 1361 // Convenience function to be used in situations where the heap type can be 1362 // asserted to be this type. 1363 static G1CollectedHeap* heap(); 1364 1365 void set_region_short_lived_locked(HeapRegion* hr); 1366 // add appropriate methods for any other surv rate groups 1367 1368 YoungList* young_list() const { return _young_list; } 1369 1370 uint old_regions_count() const { return _old_set.length(); } 1371 1372 uint humongous_regions_count() const { return _humongous_set.length(); } 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 bool isMarkedPrev(oop obj) const; 1393 bool isMarkedNext(oop obj) const; 1394 1395 // Determine if an object is dead, given the object and also 1396 // the region to which the object belongs. An object is dead 1397 // iff a) it was not allocated since the last mark, b) it 1398 // is not marked, and c) it is not in an archive region. 1399 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1400 return 1401 !hr->obj_allocated_since_prev_marking(obj) && 1402 !isMarkedPrev(obj) && 1403 !hr->is_archive(); 1404 } 1405 1406 // This function returns true when an object has been 1407 // around since the previous marking and hasn't yet 1408 // been marked during this marking, and is not in an archive region. 1409 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1410 return 1411 !hr->obj_allocated_since_next_marking(obj) && 1412 !isMarkedNext(obj) && 1413 !hr->is_archive(); 1414 } 1415 1416 // Determine if an object is dead, given only the object itself. 1417 // This will find the region to which the object belongs and 1418 // then call the region version of the same function. 1419 1420 // Added if it is NULL it isn't dead. 1421 1422 inline bool is_obj_dead(const oop obj) const; 1423 1424 inline bool is_obj_ill(const oop obj) const; 1425 1426 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1427 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1428 bool is_marked(oop obj, VerifyOption vo); 1429 const char* top_at_mark_start_str(VerifyOption vo); 1430 1431 ConcurrentMark* concurrent_mark() const { return _cm; } 1432 1433 // Refinement 1434 1435 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1436 1437 // The dirty cards region list is used to record a subset of regions 1438 // whose cards need clearing. The list if populated during the 1439 // remembered set scanning and drained during the card table 1440 // cleanup. Although the methods are reentrant, population/draining 1441 // phases must not overlap. For synchronization purposes the last 1442 // element on the list points to itself. 1443 HeapRegion* _dirty_cards_region_list; 1444 void push_dirty_cards_region(HeapRegion* hr); 1445 HeapRegion* pop_dirty_cards_region(); 1446 1447 // Optimized nmethod scanning support routines 1448 1449 // Register the given nmethod with the G1 heap. 1450 virtual void register_nmethod(nmethod* nm); 1451 1452 // Unregister the given nmethod from the G1 heap. 1453 virtual void unregister_nmethod(nmethod* nm); 1454 1455 // Free up superfluous code root memory. 1456 void purge_code_root_memory(); 1457 1458 // Rebuild the strong code root lists for each region 1459 // after a full GC. 1460 void rebuild_strong_code_roots(); 1461 1462 // Delete entries for dead interned string and clean up unreferenced symbols 1463 // in symbol table, possibly in parallel. 1464 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1465 1466 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1467 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1468 1469 // Redirty logged cards in the refinement queue. 1470 void redirty_logged_cards(); 1471 // Verification 1472 1473 // Perform any cleanup actions necessary before allowing a verification. 1474 virtual void prepare_for_verify(); 1475 1476 // Perform verification. 1477 1478 // vo == UsePrevMarking -> use "prev" marking information, 1479 // vo == UseNextMarking -> use "next" marking information 1480 // vo == UseMarkWord -> use the mark word in the object header 1481 // 1482 // NOTE: Only the "prev" marking information is guaranteed to be 1483 // consistent most of the time, so most calls to this should use 1484 // vo == UsePrevMarking. 1485 // Currently, there is only one case where this is called with 1486 // vo == UseNextMarking, which is to verify the "next" marking 1487 // information at the end of remark. 1488 // Currently there is only one place where this is called with 1489 // vo == UseMarkWord, which is to verify the marking during a 1490 // full GC. 1491 void verify(VerifyOption vo); 1492 1493 // The methods below are here for convenience and dispatch the 1494 // appropriate method depending on value of the given VerifyOption 1495 // parameter. The values for that parameter, and their meanings, 1496 // are the same as those above. 1497 1498 bool is_obj_dead_cond(const oop obj, 1499 const HeapRegion* hr, 1500 const VerifyOption vo) const; 1501 1502 bool is_obj_dead_cond(const oop obj, 1503 const VerifyOption vo) const; 1504 1505 G1HeapSummary create_g1_heap_summary(); 1506 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1507 1508 // Printing 1509 1510 virtual void print_on(outputStream* st) const; 1511 virtual void print_extended_on(outputStream* st) const; 1512 virtual void print_on_error(outputStream* st) const; 1513 1514 virtual void print_gc_threads_on(outputStream* st) const; 1515 virtual void gc_threads_do(ThreadClosure* tc) const; 1516 1517 // Override 1518 void print_tracing_info() const; 1519 1520 // The following two methods are helpful for debugging RSet issues. 1521 void print_cset_rsets() PRODUCT_RETURN; 1522 void print_all_rsets() PRODUCT_RETURN; 1523 1524 public: 1525 size_t pending_card_num(); 1526 1527 protected: 1528 size_t _max_heap_capacity; 1529 }; 1530 1531 class G1ParEvacuateFollowersClosure : public VoidClosure { 1532 private: 1533 double _start_term; 1534 double _term_time; 1535 size_t _term_attempts; 1536 1537 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1538 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1539 protected: 1540 G1CollectedHeap* _g1h; 1541 G1ParScanThreadState* _par_scan_state; 1542 RefToScanQueueSet* _queues; 1543 ParallelTaskTerminator* _terminator; 1544 1545 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1546 RefToScanQueueSet* queues() { return _queues; } 1547 ParallelTaskTerminator* terminator() { return _terminator; } 1548 1549 public: 1550 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1551 G1ParScanThreadState* par_scan_state, 1552 RefToScanQueueSet* queues, 1553 ParallelTaskTerminator* terminator) 1554 : _g1h(g1h), _par_scan_state(par_scan_state), 1555 _queues(queues), _terminator(terminator), 1556 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1557 1558 void do_void(); 1559 1560 double term_time() const { return _term_time; } 1561 size_t term_attempts() const { return _term_attempts; } 1562 1563 private: 1564 inline bool offer_termination(); 1565 }; 1566 1567 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP