Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp @ 616:4f360ec815ba
6720309: G1: don't synchronously update RSet during evacuation pauses
6720334: G1: don't update RSets of collection set regions during an evacuation pause
Summary: Introduced a deferred update mechanism for delaying the rset updates during the collection pause
Reviewed-by: apetrusenko, tonyp
| author | iveresov |
|---|---|
| date | Fri, 06 Mar 2009 13:50:14 -0800 |
| parents | 58054a18d735 |
| children | 7bb995fbd3c0 6c4cea9bfa11 |
| rev | line source |
|---|---|
| 342 | 1 /* |
| 470 | 2 * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved. |
| 342 | 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. | |
| 26 // It uses the "Garbage First" heap organization and algorithm, which | |
| 27 // may combine concurrent marking with parallel, incremental compaction of | |
| 28 // heap subsets that will yield large amounts of garbage. | |
| 29 | |
| 30 class HeapRegion; | |
| 31 class HeapRegionSeq; | |
| 32 class HeapRegionList; | |
| 33 class PermanentGenerationSpec; | |
| 34 class GenerationSpec; | |
| 35 class OopsInHeapRegionClosure; | |
| 36 class G1ScanHeapEvacClosure; | |
| 37 class ObjectClosure; | |
| 38 class SpaceClosure; | |
| 39 class CompactibleSpaceClosure; | |
| 40 class Space; | |
| 41 class G1CollectorPolicy; | |
| 42 class GenRemSet; | |
| 43 class G1RemSet; | |
| 44 class HeapRegionRemSetIterator; | |
| 45 class ConcurrentMark; | |
| 46 class ConcurrentMarkThread; | |
| 47 class ConcurrentG1Refine; | |
| 48 class ConcurrentZFThread; | |
| 49 | |
| 50 // If want to accumulate detailed statistics on work queues | |
| 51 // turn this on. | |
| 52 #define G1_DETAILED_STATS 0 | |
| 53 | |
| 54 #if G1_DETAILED_STATS | |
| 55 # define IF_G1_DETAILED_STATS(code) code | |
| 56 #else | |
| 57 # define IF_G1_DETAILED_STATS(code) | |
| 58 #endif | |
| 59 | |
| 60 typedef GenericTaskQueue<oop*> RefToScanQueue; | |
| 61 typedef GenericTaskQueueSet<oop*> RefToScanQueueSet; | |
| 62 | |
| 63 enum G1GCThreadGroups { | |
| 64 G1CRGroup = 0, | |
| 65 G1ZFGroup = 1, | |
| 66 G1CMGroup = 2, | |
| 67 G1CLGroup = 3 | |
| 68 }; | |
| 69 | |
| 70 enum GCAllocPurpose { | |
| 71 GCAllocForTenured, | |
| 72 GCAllocForSurvived, | |
| 73 GCAllocPurposeCount | |
| 74 }; | |
| 75 | |
| 76 class YoungList : public CHeapObj { | |
| 77 private: | |
| 78 G1CollectedHeap* _g1h; | |
| 79 | |
| 80 HeapRegion* _head; | |
| 81 | |
| 82 HeapRegion* _scan_only_head; | |
| 83 HeapRegion* _scan_only_tail; | |
| 84 size_t _length; | |
| 85 size_t _scan_only_length; | |
| 86 | |
| 87 size_t _last_sampled_rs_lengths; | |
| 88 size_t _sampled_rs_lengths; | |
| 89 HeapRegion* _curr; | |
| 90 HeapRegion* _curr_scan_only; | |
| 91 | |
| 92 HeapRegion* _survivor_head; | |
| 545 | 93 HeapRegion* _survivor_tail; |
| 342 | 94 size_t _survivor_length; |
| 95 | |
| 96 void empty_list(HeapRegion* list); | |
| 97 | |
| 98 public: | |
| 99 YoungList(G1CollectedHeap* g1h); | |
| 100 | |
| 101 void push_region(HeapRegion* hr); | |
| 102 void add_survivor_region(HeapRegion* hr); | |
| 103 HeapRegion* pop_region(); | |
| 104 void empty_list(); | |
| 105 bool is_empty() { return _length == 0; } | |
| 106 size_t length() { return _length; } | |
| 107 size_t scan_only_length() { return _scan_only_length; } | |
| 545 | 108 size_t survivor_length() { return _survivor_length; } |
| 342 | 109 |
| 110 void rs_length_sampling_init(); | |
| 111 bool rs_length_sampling_more(); | |
| 112 void rs_length_sampling_next(); | |
| 113 | |
| 114 void reset_sampled_info() { | |
| 115 _last_sampled_rs_lengths = 0; | |
| 116 } | |
| 117 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } | |
| 118 | |
| 119 // for development purposes | |
| 120 void reset_auxilary_lists(); | |
| 121 HeapRegion* first_region() { return _head; } | |
| 122 HeapRegion* first_scan_only_region() { return _scan_only_head; } | |
| 123 HeapRegion* first_survivor_region() { return _survivor_head; } | |
| 545 | 124 HeapRegion* last_survivor_region() { return _survivor_tail; } |
| 342 | 125 HeapRegion* par_get_next_scan_only_region() { |
| 126 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); | |
| 127 HeapRegion* ret = _curr_scan_only; | |
| 128 if (ret != NULL) | |
| 129 _curr_scan_only = ret->get_next_young_region(); | |
| 130 return ret; | |
| 131 } | |
| 132 | |
| 133 // debugging | |
| 134 bool check_list_well_formed(); | |
| 135 bool check_list_empty(bool ignore_scan_only_list, | |
| 136 bool check_sample = true); | |
| 137 void print(); | |
| 138 }; | |
| 139 | |
| 140 class RefineCardTableEntryClosure; | |
| 141 class G1CollectedHeap : public SharedHeap { | |
| 142 friend class VM_G1CollectForAllocation; | |
| 143 friend class VM_GenCollectForPermanentAllocation; | |
| 144 friend class VM_G1CollectFull; | |
| 145 friend class VM_G1IncCollectionPause; | |
| 146 friend class VM_G1PopRegionCollectionPause; | |
| 147 friend class VMStructs; | |
| 148 | |
| 149 // Closures used in implementation. | |
| 150 friend class G1ParCopyHelper; | |
| 151 friend class G1IsAliveClosure; | |
| 152 friend class G1EvacuateFollowersClosure; | |
| 153 friend class G1ParScanThreadState; | |
| 154 friend class G1ParScanClosureSuper; | |
| 155 friend class G1ParEvacuateFollowersClosure; | |
| 156 friend class G1ParTask; | |
| 157 friend class G1FreeGarbageRegionClosure; | |
| 158 friend class RefineCardTableEntryClosure; | |
| 159 friend class G1PrepareCompactClosure; | |
| 160 friend class RegionSorter; | |
| 161 friend class CountRCClosure; | |
| 162 friend class EvacPopObjClosure; | |
| 163 | |
| 164 // Other related classes. | |
| 165 friend class G1MarkSweep; | |
| 166 | |
| 167 private: | |
| 168 enum SomePrivateConstants { | |
| 169 VeryLargeInBytes = HeapRegion::GrainBytes/2, | |
| 170 VeryLargeInWords = VeryLargeInBytes/HeapWordSize, | |
| 171 MinHeapDeltaBytes = 10 * HeapRegion::GrainBytes, // FIXME | |
| 172 NumAPIs = HeapRegion::MaxAge | |
| 173 }; | |
| 174 | |
| 175 | |
| 176 // The one and only G1CollectedHeap, so static functions can find it. | |
| 177 static G1CollectedHeap* _g1h; | |
| 178 | |
| 179 // Storage for the G1 heap (excludes the permanent generation). | |
| 180 VirtualSpace _g1_storage; | |
| 181 MemRegion _g1_reserved; | |
| 182 | |
| 183 // The part of _g1_storage that is currently committed. | |
| 184 MemRegion _g1_committed; | |
| 185 | |
| 186 // The maximum part of _g1_storage that has ever been committed. | |
| 187 MemRegion _g1_max_committed; | |
| 188 | |
| 189 // The number of regions that are completely free. | |
| 190 size_t _free_regions; | |
| 191 | |
| 192 // The number of regions we could create by expansion. | |
| 193 size_t _expansion_regions; | |
| 194 | |
| 195 // Return the number of free regions in the heap (by direct counting.) | |
| 196 size_t count_free_regions(); | |
| 197 // Return the number of free regions on the free and unclean lists. | |
| 198 size_t count_free_regions_list(); | |
| 199 | |
| 200 // The block offset table for the G1 heap. | |
| 201 G1BlockOffsetSharedArray* _bot_shared; | |
| 202 | |
| 203 // Move all of the regions off the free lists, then rebuild those free | |
| 204 // lists, before and after full GC. | |
| 205 void tear_down_region_lists(); | |
| 206 void rebuild_region_lists(); | |
| 207 // This sets all non-empty regions to need zero-fill (which they will if | |
| 208 // they are empty after full collection.) | |
| 209 void set_used_regions_to_need_zero_fill(); | |
| 210 | |
| 211 // The sequence of all heap regions in the heap. | |
| 212 HeapRegionSeq* _hrs; | |
| 213 | |
| 214 // The region from which normal-sized objects are currently being | |
| 215 // allocated. May be NULL. | |
| 216 HeapRegion* _cur_alloc_region; | |
| 217 | |
| 218 // Postcondition: cur_alloc_region == NULL. | |
| 219 void abandon_cur_alloc_region(); | |
| 220 | |
| 221 // The to-space memory regions into which objects are being copied during | |
| 222 // a GC. | |
| 223 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount]; | |
| 545 | 224 size_t _gc_alloc_region_counts[GCAllocPurposeCount]; |
| 342 | 225 |
| 226 // A list of the regions that have been set to be alloc regions in the | |
| 227 // current collection. | |
| 228 HeapRegion* _gc_alloc_region_list; | |
| 229 | |
| 230 // When called by par thread, require par_alloc_during_gc_lock() to be held. | |
| 231 void push_gc_alloc_region(HeapRegion* hr); | |
| 232 | |
| 233 // This should only be called single-threaded. Undeclares all GC alloc | |
| 234 // regions. | |
| 235 void forget_alloc_region_list(); | |
| 236 | |
| 237 // Should be used to set an alloc region, because there's other | |
| 238 // associated bookkeeping. | |
| 239 void set_gc_alloc_region(int purpose, HeapRegion* r); | |
| 240 | |
| 241 // Check well-formedness of alloc region list. | |
| 242 bool check_gc_alloc_regions(); | |
| 243 | |
| 244 // Outside of GC pauses, the number of bytes used in all regions other | |
| 245 // than the current allocation region. | |
| 246 size_t _summary_bytes_used; | |
| 247 | |
| 248 // Summary information about popular objects; method to print it. | |
| 249 NumberSeq _pop_obj_rc_at_copy; | |
| 250 void print_popularity_summary_info() const; | |
| 251 | |
| 526 | 252 // This is used for a quick test on whether a reference points into |
| 253 // the collection set or not. Basically, we have an array, with one | |
| 254 // byte per region, and that byte denotes whether the corresponding | |
| 255 // region is in the collection set or not. The entry corresponding | |
| 256 // the bottom of the heap, i.e., region 0, is pointed to by | |
| 257 // _in_cset_fast_test_base. The _in_cset_fast_test field has been | |
| 258 // biased so that it actually points to address 0 of the address | |
| 259 // space, to make the test as fast as possible (we can simply shift | |
| 260 // the address to address into it, instead of having to subtract the | |
| 261 // bottom of the heap from the address before shifting it; basically | |
| 262 // it works in the same way the card table works). | |
| 263 bool* _in_cset_fast_test; | |
| 264 | |
| 265 // The allocated array used for the fast test on whether a reference | |
| 266 // points into the collection set or not. This field is also used to | |
| 267 // free the array. | |
| 268 bool* _in_cset_fast_test_base; | |
| 269 | |
| 270 // The length of the _in_cset_fast_test_base array. | |
| 271 size_t _in_cset_fast_test_length; | |
| 272 | |
|
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9bb2c10ac07b
6723570: G1: assertion failure: p == current_top or oop(p)->is_oop(),"p is not a block start" (revisited!)
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273 volatile unsigned _gc_time_stamp; |
| 342 | 274 |
| 275 size_t* _surviving_young_words; | |
| 276 | |
| 277 void setup_surviving_young_words(); | |
| 278 void update_surviving_young_words(size_t* surv_young_words); | |
| 279 void cleanup_surviving_young_words(); | |
| 280 | |
| 281 protected: | |
| 282 | |
| 283 // Returns "true" iff none of the gc alloc regions have any allocations | |
| 284 // since the last call to "save_marks". | |
| 285 bool all_alloc_regions_no_allocs_since_save_marks(); | |
| 545 | 286 // Perform finalization stuff on all allocation regions. |
| 287 void retire_all_alloc_regions(); | |
| 342 | 288 |
| 289 // The number of regions allocated to hold humongous objects. | |
| 290 int _num_humongous_regions; | |
| 291 YoungList* _young_list; | |
| 292 | |
| 293 // The current policy object for the collector. | |
| 294 G1CollectorPolicy* _g1_policy; | |
| 295 | |
| 296 // Parallel allocation lock to protect the current allocation region. | |
| 297 Mutex _par_alloc_during_gc_lock; | |
| 298 Mutex* par_alloc_during_gc_lock() { return &_par_alloc_during_gc_lock; } | |
| 299 | |
| 300 // If possible/desirable, allocate a new HeapRegion for normal object | |
| 301 // allocation sufficient for an allocation of the given "word_size". | |
| 302 // If "do_expand" is true, will attempt to expand the heap if necessary | |
| 303 // to to satisfy the request. If "zero_filled" is true, requires a | |
| 304 // zero-filled region. | |
| 305 // (Returning NULL will trigger a GC.) | |
| 306 virtual HeapRegion* newAllocRegion_work(size_t word_size, | |
| 307 bool do_expand, | |
| 308 bool zero_filled); | |
| 309 | |
| 310 virtual HeapRegion* newAllocRegion(size_t word_size, | |
| 311 bool zero_filled = true) { | |
| 312 return newAllocRegion_work(word_size, false, zero_filled); | |
| 313 } | |
| 314 virtual HeapRegion* newAllocRegionWithExpansion(int purpose, | |
| 315 size_t word_size, | |
| 316 bool zero_filled = true); | |
| 317 | |
| 318 // Attempt to allocate an object of the given (very large) "word_size". | |
| 319 // Returns "NULL" on failure. | |
| 320 virtual HeapWord* humongousObjAllocate(size_t word_size); | |
| 321 | |
| 322 // If possible, allocate a block of the given word_size, else return "NULL". | |
| 323 // Returning NULL will trigger GC or heap expansion. | |
| 324 // These two methods have rather awkward pre- and | |
| 325 // post-conditions. If they are called outside a safepoint, then | |
| 326 // they assume that the caller is holding the heap lock. Upon return | |
| 327 // they release the heap lock, if they are returning a non-NULL | |
| 328 // value. attempt_allocation_slow() also dirties the cards of a | |
| 329 // newly-allocated young region after it releases the heap | |
| 330 // lock. This change in interface was the neatest way to achieve | |
| 331 // this card dirtying without affecting mem_allocate(), which is a | |
| 332 // more frequently called method. We tried two or three different | |
| 333 // approaches, but they were even more hacky. | |
| 334 HeapWord* attempt_allocation(size_t word_size, | |
| 335 bool permit_collection_pause = true); | |
| 336 | |
| 337 HeapWord* attempt_allocation_slow(size_t word_size, | |
| 338 bool permit_collection_pause = true); | |
| 339 | |
| 340 // Allocate blocks during garbage collection. Will ensure an | |
| 341 // allocation region, either by picking one or expanding the | |
| 342 // heap, and then allocate a block of the given size. The block | |
| 343 // may not be a humongous - it must fit into a single heap region. | |
| 344 HeapWord* allocate_during_gc(GCAllocPurpose purpose, size_t word_size); | |
| 345 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); | |
| 346 | |
| 347 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, | |
| 348 HeapRegion* alloc_region, | |
| 349 bool par, | |
| 350 size_t word_size); | |
| 351 | |
| 352 // Ensure that no further allocations can happen in "r", bearing in mind | |
| 353 // that parallel threads might be attempting allocations. | |
| 354 void par_allocate_remaining_space(HeapRegion* r); | |
| 355 | |
| 545 | 356 // Retires an allocation region when it is full or at the end of a |
| 357 // GC pause. | |
| 358 void retire_alloc_region(HeapRegion* alloc_region, bool par); | |
| 359 | |
| 342 | 360 // Helper function for two callbacks below. |
| 361 // "full", if true, indicates that the GC is for a System.gc() request, | |
| 362 // and should collect the entire heap. If "clear_all_soft_refs" is true, | |
| 363 // all soft references are cleared during the GC. If "full" is false, | |
| 364 // "word_size" describes the allocation that the GC should | |
| 365 // attempt (at least) to satisfy. | |
| 366 void do_collection(bool full, bool clear_all_soft_refs, | |
| 367 size_t word_size); | |
| 368 | |
| 369 // Callback from VM_G1CollectFull operation. | |
| 370 // Perform a full collection. | |
| 371 void do_full_collection(bool clear_all_soft_refs); | |
| 372 | |
| 373 // Resize the heap if necessary after a full collection. If this is | |
| 374 // after a collect-for allocation, "word_size" is the allocation size, | |
| 375 // and will be considered part of the used portion of the heap. | |
| 376 void resize_if_necessary_after_full_collection(size_t word_size); | |
| 377 | |
| 378 // Callback from VM_G1CollectForAllocation operation. | |
| 379 // This function does everything necessary/possible to satisfy a | |
| 380 // failed allocation request (including collection, expansion, etc.) | |
| 381 HeapWord* satisfy_failed_allocation(size_t word_size); | |
| 382 | |
| 383 // Attempting to expand the heap sufficiently | |
| 384 // to support an allocation of the given "word_size". If | |
| 385 // successful, perform the allocation and return the address of the | |
| 386 // allocated block, or else "NULL". | |
| 387 virtual HeapWord* expand_and_allocate(size_t word_size); | |
| 388 | |
| 389 public: | |
| 390 // Expand the garbage-first heap by at least the given size (in bytes!). | |
| 391 // (Rounds up to a HeapRegion boundary.) | |
| 392 virtual void expand(size_t expand_bytes); | |
| 393 | |
| 394 // Do anything common to GC's. | |
| 395 virtual void gc_prologue(bool full); | |
| 396 virtual void gc_epilogue(bool full); | |
| 397 | |
| 526 | 398 // We register a region with the fast "in collection set" test. We |
| 399 // simply set to true the array slot corresponding to this region. | |
| 400 void register_region_with_in_cset_fast_test(HeapRegion* r) { | |
| 401 assert(_in_cset_fast_test_base != NULL, "sanity"); | |
| 402 assert(r->in_collection_set(), "invariant"); | |
| 403 int index = r->hrs_index(); | |
| 404 assert(0 <= (size_t) index && (size_t) index < _in_cset_fast_test_length, | |
| 405 "invariant"); | |
| 406 assert(!_in_cset_fast_test_base[index], "invariant"); | |
| 407 _in_cset_fast_test_base[index] = true; | |
| 408 } | |
| 409 | |
| 410 // This is a fast test on whether a reference points into the | |
| 411 // collection set or not. It does not assume that the reference | |
| 412 // points into the heap; if it doesn't, it will return false. | |
| 413 bool in_cset_fast_test(oop obj) { | |
| 414 assert(_in_cset_fast_test != NULL, "sanity"); | |
| 415 if (_g1_committed.contains((HeapWord*) obj)) { | |
| 416 // no need to subtract the bottom of the heap from obj, | |
| 417 // _in_cset_fast_test is biased | |
| 418 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes; | |
| 419 bool ret = _in_cset_fast_test[index]; | |
| 420 // let's make sure the result is consistent with what the slower | |
| 421 // test returns | |
| 422 assert( ret || !obj_in_cs(obj), "sanity"); | |
| 423 assert(!ret || obj_in_cs(obj), "sanity"); | |
| 424 return ret; | |
| 425 } else { | |
| 426 return false; | |
| 427 } | |
| 428 } | |
| 429 | |
| 342 | 430 protected: |
| 431 | |
| 432 // Shrink the garbage-first heap by at most the given size (in bytes!). | |
| 433 // (Rounds down to a HeapRegion boundary.) | |
| 434 virtual void shrink(size_t expand_bytes); | |
| 435 void shrink_helper(size_t expand_bytes); | |
| 436 | |
| 437 // Do an incremental collection: identify a collection set, and evacuate | |
| 438 // its live objects elsewhere. | |
| 439 virtual void do_collection_pause(); | |
| 440 | |
| 441 // The guts of the incremental collection pause, executed by the vm | |
| 442 // thread. If "popular_region" is non-NULL, this pause should evacuate | |
| 443 // this single region whose remembered set has gotten large, moving | |
| 444 // any popular objects to one of the popular regions. | |
| 445 virtual void do_collection_pause_at_safepoint(HeapRegion* popular_region); | |
| 446 | |
| 447 // Actually do the work of evacuating the collection set. | |
| 448 virtual void evacuate_collection_set(); | |
| 449 | |
| 450 // If this is an appropriate right time, do a collection pause. | |
| 451 // The "word_size" argument, if non-zero, indicates the size of an | |
| 452 // allocation request that is prompting this query. | |
| 453 void do_collection_pause_if_appropriate(size_t word_size); | |
| 454 | |
| 455 // The g1 remembered set of the heap. | |
| 456 G1RemSet* _g1_rem_set; | |
| 457 // And it's mod ref barrier set, used to track updates for the above. | |
| 458 ModRefBarrierSet* _mr_bs; | |
| 459 | |
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460 // A set of cards that cover the objects for which the Rsets should be updated |
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461 // concurrently after the collection. |
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462 DirtyCardQueueSet _dirty_card_queue_set; |
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463 |
| 342 | 464 // The Heap Region Rem Set Iterator. |
| 465 HeapRegionRemSetIterator** _rem_set_iterator; | |
| 466 | |
| 467 // The closure used to refine a single card. | |
| 468 RefineCardTableEntryClosure* _refine_cte_cl; | |
| 469 | |
| 470 // A function to check the consistency of dirty card logs. | |
| 471 void check_ct_logs_at_safepoint(); | |
| 472 | |
| 473 // After a collection pause, make the regions in the CS into free | |
| 474 // regions. | |
| 475 void free_collection_set(HeapRegion* cs_head); | |
| 476 | |
| 477 // Applies "scan_non_heap_roots" to roots outside the heap, | |
| 478 // "scan_rs" to roots inside the heap (having done "set_region" to | |
| 479 // indicate the region in which the root resides), and does "scan_perm" | |
| 480 // (setting the generation to the perm generation.) If "scan_rs" is | |
| 481 // NULL, then this step is skipped. The "worker_i" | |
| 482 // param is for use with parallel roots processing, and should be | |
| 483 // the "i" of the calling parallel worker thread's work(i) function. | |
| 484 // In the sequential case this param will be ignored. | |
| 485 void g1_process_strong_roots(bool collecting_perm_gen, | |
| 486 SharedHeap::ScanningOption so, | |
| 487 OopClosure* scan_non_heap_roots, | |
| 488 OopsInHeapRegionClosure* scan_rs, | |
| 489 OopsInHeapRegionClosure* scan_so, | |
| 490 OopsInGenClosure* scan_perm, | |
| 491 int worker_i); | |
| 492 | |
| 493 void scan_scan_only_set(OopsInHeapRegionClosure* oc, | |
| 494 int worker_i); | |
| 495 void scan_scan_only_region(HeapRegion* hr, | |
| 496 OopsInHeapRegionClosure* oc, | |
| 497 int worker_i); | |
| 498 | |
| 499 // Apply "blk" to all the weak roots of the system. These include | |
| 500 // JNI weak roots, the code cache, system dictionary, symbol table, | |
| 501 // string table, and referents of reachable weak refs. | |
| 502 void g1_process_weak_roots(OopClosure* root_closure, | |
| 503 OopClosure* non_root_closure); | |
| 504 | |
| 505 // Invoke "save_marks" on all heap regions. | |
| 506 void save_marks(); | |
| 507 | |
| 508 // Free a heap region. | |
| 509 void free_region(HeapRegion* hr); | |
| 510 // A component of "free_region", exposed for 'batching'. | |
| 511 // All the params after "hr" are out params: the used bytes of the freed | |
| 512 // region(s), the number of H regions cleared, the number of regions | |
| 513 // freed, and pointers to the head and tail of a list of freed contig | |
| 514 // regions, linked throught the "next_on_unclean_list" field. | |
| 515 void free_region_work(HeapRegion* hr, | |
| 516 size_t& pre_used, | |
| 517 size_t& cleared_h, | |
| 518 size_t& freed_regions, | |
| 519 UncleanRegionList* list, | |
| 520 bool par = false); | |
| 521 | |
| 522 | |
| 523 // The concurrent marker (and the thread it runs in.) | |
| 524 ConcurrentMark* _cm; | |
| 525 ConcurrentMarkThread* _cmThread; | |
| 526 bool _mark_in_progress; | |
| 527 | |
| 528 // The concurrent refiner. | |
| 529 ConcurrentG1Refine* _cg1r; | |
| 530 | |
| 531 // The concurrent zero-fill thread. | |
| 532 ConcurrentZFThread* _czft; | |
| 533 | |
| 534 // The parallel task queues | |
| 535 RefToScanQueueSet *_task_queues; | |
| 536 | |
| 537 // True iff a evacuation has failed in the current collection. | |
| 538 bool _evacuation_failed; | |
| 539 | |
| 540 // Set the attribute indicating whether evacuation has failed in the | |
| 541 // current collection. | |
| 542 void set_evacuation_failed(bool b) { _evacuation_failed = b; } | |
| 543 | |
| 544 // Failed evacuations cause some logical from-space objects to have | |
| 545 // forwarding pointers to themselves. Reset them. | |
| 546 void remove_self_forwarding_pointers(); | |
| 547 | |
| 548 // When one is non-null, so is the other. Together, they each pair is | |
| 549 // an object with a preserved mark, and its mark value. | |
| 550 GrowableArray<oop>* _objs_with_preserved_marks; | |
| 551 GrowableArray<markOop>* _preserved_marks_of_objs; | |
| 552 | |
| 553 // Preserve the mark of "obj", if necessary, in preparation for its mark | |
| 554 // word being overwritten with a self-forwarding-pointer. | |
| 555 void preserve_mark_if_necessary(oop obj, markOop m); | |
| 556 | |
| 557 // The stack of evac-failure objects left to be scanned. | |
| 558 GrowableArray<oop>* _evac_failure_scan_stack; | |
| 559 // The closure to apply to evac-failure objects. | |
| 560 | |
| 561 OopsInHeapRegionClosure* _evac_failure_closure; | |
| 562 // Set the field above. | |
| 563 void | |
| 564 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { | |
| 565 _evac_failure_closure = evac_failure_closure; | |
| 566 } | |
| 567 | |
| 568 // Push "obj" on the scan stack. | |
| 569 void push_on_evac_failure_scan_stack(oop obj); | |
| 570 // Process scan stack entries until the stack is empty. | |
| 571 void drain_evac_failure_scan_stack(); | |
| 572 // True iff an invocation of "drain_scan_stack" is in progress; to | |
| 573 // prevent unnecessary recursion. | |
| 574 bool _drain_in_progress; | |
| 575 | |
| 576 // Do any necessary initialization for evacuation-failure handling. | |
| 577 // "cl" is the closure that will be used to process evac-failure | |
| 578 // objects. | |
| 579 void init_for_evac_failure(OopsInHeapRegionClosure* cl); | |
| 580 // Do any necessary cleanup for evacuation-failure handling data | |
| 581 // structures. | |
| 582 void finalize_for_evac_failure(); | |
| 583 | |
| 584 // An attempt to evacuate "obj" has failed; take necessary steps. | |
| 585 void handle_evacuation_failure(oop obj); | |
| 586 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj); | |
| 587 void handle_evacuation_failure_common(oop obj, markOop m); | |
| 588 | |
| 589 | |
| 590 // Ensure that the relevant gc_alloc regions are set. | |
| 591 void get_gc_alloc_regions(); | |
| 592 // We're done with GC alloc regions; release them, as appropriate. | |
| 593 void release_gc_alloc_regions(); | |
| 594 | |
| 595 // ("Weak") Reference processing support | |
| 596 ReferenceProcessor* _ref_processor; | |
| 597 | |
| 598 enum G1H_process_strong_roots_tasks { | |
| 599 G1H_PS_mark_stack_oops_do, | |
| 600 G1H_PS_refProcessor_oops_do, | |
| 601 // Leave this one last. | |
| 602 G1H_PS_NumElements | |
| 603 }; | |
| 604 | |
| 605 SubTasksDone* _process_strong_tasks; | |
| 606 | |
| 607 // Allocate space to hold a popular object. Result is guaranteed below | |
| 608 // "popular_object_boundary()". Note: CURRENTLY halts the system if we | |
| 609 // run out of space to hold popular objects. | |
| 610 HeapWord* allocate_popular_object(size_t word_size); | |
| 611 | |
| 612 // The boundary between popular and non-popular objects. | |
| 613 HeapWord* _popular_object_boundary; | |
| 614 | |
| 615 HeapRegionList* _popular_regions_to_be_evacuated; | |
| 616 | |
| 617 // Compute which objects in "single_region" are popular. If any are, | |
| 618 // evacuate them to a popular region, leaving behind forwarding pointers, | |
| 619 // and select "popular_region" as the single collection set region. | |
| 620 // Otherwise, leave the collection set null. | |
| 621 void popularity_pause_preamble(HeapRegion* populer_region); | |
| 622 | |
| 623 // Compute which objects in "single_region" are popular, and evacuate | |
| 624 // them to a popular region, leaving behind forwarding pointers. | |
| 625 // Returns "true" if at least one popular object is discovered and | |
| 626 // evacuated. In any case, "*max_rc" is set to the maximum reference | |
| 627 // count of an object in the region. | |
| 628 bool compute_reference_counts_and_evac_popular(HeapRegion* populer_region, | |
| 629 size_t* max_rc); | |
| 630 // Subroutines used in the above. | |
| 631 bool _rc_region_above; | |
| 632 size_t _rc_region_diff; | |
| 633 jint* obj_rc_addr(oop obj) { | |
| 634 uintptr_t obj_addr = (uintptr_t)obj; | |
| 635 if (_rc_region_above) { | |
| 636 jint* res = (jint*)(obj_addr + _rc_region_diff); | |
| 637 assert((uintptr_t)res > obj_addr, "RC region is above."); | |
| 638 return res; | |
| 639 } else { | |
| 640 jint* res = (jint*)(obj_addr - _rc_region_diff); | |
| 641 assert((uintptr_t)res < obj_addr, "RC region is below."); | |
| 642 return res; | |
| 643 } | |
| 644 } | |
| 645 jint obj_rc(oop obj) { | |
| 646 return *obj_rc_addr(obj); | |
| 647 } | |
| 648 void inc_obj_rc(oop obj) { | |
| 649 (*obj_rc_addr(obj))++; | |
| 650 } | |
| 651 void atomic_inc_obj_rc(oop obj); | |
| 652 | |
| 653 | |
| 654 // Number of popular objects and bytes (latter is cheaper!). | |
| 655 size_t pop_object_used_objs(); | |
| 656 size_t pop_object_used_bytes(); | |
| 657 | |
| 658 // Index of the popular region in which allocation is currently being | |
| 659 // done. | |
| 660 int _cur_pop_hr_index; | |
| 661 | |
| 662 // List of regions which require zero filling. | |
| 663 UncleanRegionList _unclean_region_list; | |
| 664 bool _unclean_regions_coming; | |
| 665 | |
| 666 bool check_age_cohort_well_formed_work(int a, HeapRegion* hr); | |
| 667 | |
| 668 public: | |
| 669 void set_refine_cte_cl_concurrency(bool concurrent); | |
| 670 | |
| 671 RefToScanQueue *task_queue(int i); | |
| 672 | |
|
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673 // A set of cards where updates happened during the GC |
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674 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } |
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675 |
| 342 | 676 // Create a G1CollectedHeap with the specified policy. |
| 677 // Must call the initialize method afterwards. | |
| 678 // May not return if something goes wrong. | |
| 679 G1CollectedHeap(G1CollectorPolicy* policy); | |
| 680 | |
| 681 // Initialize the G1CollectedHeap to have the initial and | |
| 682 // maximum sizes, permanent generation, and remembered and barrier sets | |
| 683 // specified by the policy object. | |
| 684 jint initialize(); | |
| 685 | |
| 686 void ref_processing_init(); | |
| 687 | |
| 688 void set_par_threads(int t) { | |
| 689 SharedHeap::set_par_threads(t); | |
| 690 _process_strong_tasks->set_par_threads(t); | |
| 691 } | |
| 692 | |
| 693 virtual CollectedHeap::Name kind() const { | |
| 694 return CollectedHeap::G1CollectedHeap; | |
| 695 } | |
| 696 | |
| 697 // The current policy object for the collector. | |
| 698 G1CollectorPolicy* g1_policy() const { return _g1_policy; } | |
| 699 | |
| 700 // Adaptive size policy. No such thing for g1. | |
| 701 virtual AdaptiveSizePolicy* size_policy() { return NULL; } | |
| 702 | |
| 703 // The rem set and barrier set. | |
| 704 G1RemSet* g1_rem_set() const { return _g1_rem_set; } | |
| 705 ModRefBarrierSet* mr_bs() const { return _mr_bs; } | |
| 706 | |
| 707 // The rem set iterator. | |
| 708 HeapRegionRemSetIterator* rem_set_iterator(int i) { | |
| 709 return _rem_set_iterator[i]; | |
| 710 } | |
| 711 | |
| 712 HeapRegionRemSetIterator* rem_set_iterator() { | |
| 713 return _rem_set_iterator[0]; | |
| 714 } | |
| 715 | |
| 716 unsigned get_gc_time_stamp() { | |
| 717 return _gc_time_stamp; | |
| 718 } | |
| 719 | |
| 720 void reset_gc_time_stamp() { | |
| 721 _gc_time_stamp = 0; | |
|
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722 OrderAccess::fence(); |
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723 } |
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724 |
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725 void increment_gc_time_stamp() { |
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726 ++_gc_time_stamp; |
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727 OrderAccess::fence(); |
| 342 | 728 } |
| 729 | |
| 730 void iterate_dirty_card_closure(bool concurrent, int worker_i); | |
| 731 | |
| 732 // The shared block offset table array. | |
| 733 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } | |
| 734 | |
| 735 // Reference Processing accessor | |
| 736 ReferenceProcessor* ref_processor() { return _ref_processor; } | |
| 737 | |
| 738 // Reserved (g1 only; super method includes perm), capacity and the used | |
| 739 // portion in bytes. | |
| 740 size_t g1_reserved_obj_bytes() { return _g1_reserved.byte_size(); } | |
| 741 virtual size_t capacity() const; | |
| 742 virtual size_t used() const; | |
| 743 size_t recalculate_used() const; | |
| 744 #ifndef PRODUCT | |
| 745 size_t recalculate_used_regions() const; | |
| 746 #endif // PRODUCT | |
| 747 | |
| 748 // These virtual functions do the actual allocation. | |
| 749 virtual HeapWord* mem_allocate(size_t word_size, | |
| 750 bool is_noref, | |
| 751 bool is_tlab, | |
| 752 bool* gc_overhead_limit_was_exceeded); | |
| 753 | |
| 754 // Some heaps may offer a contiguous region for shared non-blocking | |
| 755 // allocation, via inlined code (by exporting the address of the top and | |
| 756 // end fields defining the extent of the contiguous allocation region.) | |
| 757 // But G1CollectedHeap doesn't yet support this. | |
| 758 | |
| 759 // Return an estimate of the maximum allocation that could be performed | |
| 760 // without triggering any collection or expansion activity. In a | |
| 761 // generational collector, for example, this is probably the largest | |
| 762 // allocation that could be supported (without expansion) in the youngest | |
| 763 // generation. It is "unsafe" because no locks are taken; the result | |
| 764 // should be treated as an approximation, not a guarantee, for use in | |
| 765 // heuristic resizing decisions. | |
| 766 virtual size_t unsafe_max_alloc(); | |
| 767 | |
| 768 virtual bool is_maximal_no_gc() const { | |
| 769 return _g1_storage.uncommitted_size() == 0; | |
| 770 } | |
| 771 | |
| 772 // The total number of regions in the heap. | |
| 773 size_t n_regions(); | |
| 774 | |
| 775 // The number of regions that are completely free. | |
| 776 size_t max_regions(); | |
| 777 | |
| 778 // The number of regions that are completely free. | |
| 779 size_t free_regions(); | |
| 780 | |
| 781 // The number of regions that are not completely free. | |
| 782 size_t used_regions() { return n_regions() - free_regions(); } | |
| 783 | |
| 784 // True iff the ZF thread should run. | |
| 785 bool should_zf(); | |
| 786 | |
| 787 // The number of regions available for "regular" expansion. | |
| 788 size_t expansion_regions() { return _expansion_regions; } | |
| 789 | |
| 790 #ifndef PRODUCT | |
| 791 bool regions_accounted_for(); | |
| 792 bool print_region_accounting_info(); | |
| 793 void print_region_counts(); | |
| 794 #endif | |
| 795 | |
| 796 HeapRegion* alloc_region_from_unclean_list(bool zero_filled); | |
| 797 HeapRegion* alloc_region_from_unclean_list_locked(bool zero_filled); | |
| 798 | |
| 799 void put_region_on_unclean_list(HeapRegion* r); | |
| 800 void put_region_on_unclean_list_locked(HeapRegion* r); | |
| 801 | |
| 802 void prepend_region_list_on_unclean_list(UncleanRegionList* list); | |
| 803 void prepend_region_list_on_unclean_list_locked(UncleanRegionList* list); | |
| 804 | |
| 805 void set_unclean_regions_coming(bool b); | |
| 806 void set_unclean_regions_coming_locked(bool b); | |
| 807 // Wait for cleanup to be complete. | |
| 808 void wait_for_cleanup_complete(); | |
| 809 // Like above, but assumes that the calling thread owns the Heap_lock. | |
| 810 void wait_for_cleanup_complete_locked(); | |
| 811 | |
| 812 // Return the head of the unclean list. | |
| 813 HeapRegion* peek_unclean_region_list_locked(); | |
| 814 // Remove and return the head of the unclean list. | |
| 815 HeapRegion* pop_unclean_region_list_locked(); | |
| 816 | |
| 817 // List of regions which are zero filled and ready for allocation. | |
| 818 HeapRegion* _free_region_list; | |
| 819 // Number of elements on the free list. | |
| 820 size_t _free_region_list_size; | |
| 821 | |
| 822 // If the head of the unclean list is ZeroFilled, move it to the free | |
| 823 // list. | |
| 824 bool move_cleaned_region_to_free_list_locked(); | |
| 825 bool move_cleaned_region_to_free_list(); | |
| 826 | |
| 827 void put_free_region_on_list_locked(HeapRegion* r); | |
| 828 void put_free_region_on_list(HeapRegion* r); | |
| 829 | |
| 830 // Remove and return the head element of the free list. | |
| 831 HeapRegion* pop_free_region_list_locked(); | |
| 832 | |
| 833 // If "zero_filled" is true, we first try the free list, then we try the | |
| 834 // unclean list, zero-filling the result. If "zero_filled" is false, we | |
| 835 // first try the unclean list, then the zero-filled list. | |
| 836 HeapRegion* alloc_free_region_from_lists(bool zero_filled); | |
| 837 | |
| 838 // Verify the integrity of the region lists. | |
| 839 void remove_allocated_regions_from_lists(); | |
| 840 bool verify_region_lists(); | |
| 841 bool verify_region_lists_locked(); | |
| 842 size_t unclean_region_list_length(); | |
| 843 size_t free_region_list_length(); | |
| 844 | |
| 845 // Perform a collection of the heap; intended for use in implementing | |
| 846 // "System.gc". This probably implies as full a collection as the | |
| 847 // "CollectedHeap" supports. | |
| 848 virtual void collect(GCCause::Cause cause); | |
| 849 | |
| 850 // The same as above but assume that the caller holds the Heap_lock. | |
| 851 void collect_locked(GCCause::Cause cause); | |
| 852 | |
| 853 // This interface assumes that it's being called by the | |
| 854 // vm thread. It collects the heap assuming that the | |
| 855 // heap lock is already held and that we are executing in | |
| 856 // the context of the vm thread. | |
| 857 virtual void collect_as_vm_thread(GCCause::Cause cause); | |
| 858 | |
| 859 // True iff a evacuation has failed in the most-recent collection. | |
| 860 bool evacuation_failed() { return _evacuation_failed; } | |
| 861 | |
| 862 // Free a region if it is totally full of garbage. Returns the number of | |
| 863 // bytes freed (0 ==> didn't free it). | |
| 864 size_t free_region_if_totally_empty(HeapRegion *hr); | |
| 865 void free_region_if_totally_empty_work(HeapRegion *hr, | |
| 866 size_t& pre_used, | |
| 867 size_t& cleared_h_regions, | |
| 868 size_t& freed_regions, | |
| 869 UncleanRegionList* list, | |
| 870 bool par = false); | |
| 871 | |
| 872 // If we've done free region work that yields the given changes, update | |
| 873 // the relevant global variables. | |
| 874 void finish_free_region_work(size_t pre_used, | |
| 875 size_t cleared_h_regions, | |
| 876 size_t freed_regions, | |
| 877 UncleanRegionList* list); | |
| 878 | |
| 879 | |
| 880 // Returns "TRUE" iff "p" points into the allocated area of the heap. | |
| 881 virtual bool is_in(const void* p) const; | |
| 882 | |
| 883 // Return "TRUE" iff the given object address is within the collection | |
| 884 // set. | |
| 885 inline bool obj_in_cs(oop obj); | |
| 886 | |
| 887 // Return "TRUE" iff the given object address is in the reserved | |
| 888 // region of g1 (excluding the permanent generation). | |
| 889 bool is_in_g1_reserved(const void* p) const { | |
| 890 return _g1_reserved.contains(p); | |
| 891 } | |
| 892 | |
| 893 // Returns a MemRegion that corresponds to the space that has been | |
| 894 // committed in the heap | |
| 895 MemRegion g1_committed() { | |
| 896 return _g1_committed; | |
| 897 } | |
| 898 | |
| 899 NOT_PRODUCT( bool is_in_closed_subset(const void* p) const; ) | |
| 900 | |
| 901 // Dirty card table entries covering a list of young regions. | |
| 902 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list); | |
| 903 | |
| 904 // This resets the card table to all zeros. It is used after | |
| 905 // a collection pause which used the card table to claim cards. | |
| 906 void cleanUpCardTable(); | |
| 907 | |
| 908 // Iteration functions. | |
| 909 | |
| 910 // Iterate over all the ref-containing fields of all objects, calling | |
| 911 // "cl.do_oop" on each. | |
| 912 virtual void oop_iterate(OopClosure* cl); | |
| 913 | |
| 914 // Same as above, restricted to a memory region. | |
| 915 virtual void oop_iterate(MemRegion mr, OopClosure* cl); | |
| 916 | |
| 917 // Iterate over all objects, calling "cl.do_object" on each. | |
| 918 virtual void object_iterate(ObjectClosure* cl); | |
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919 virtual void safe_object_iterate(ObjectClosure* cl) { object_iterate(cl); } |
| 342 | 920 |
| 921 // Iterate over all objects allocated since the last collection, calling | |
| 922 // "cl.do_object" on each. The heap must have been initialized properly | |
| 923 // to support this function, or else this call will fail. | |
| 924 virtual void object_iterate_since_last_GC(ObjectClosure* cl); | |
| 925 | |
| 926 // Iterate over all spaces in use in the heap, in ascending address order. | |
| 927 virtual void space_iterate(SpaceClosure* cl); | |
| 928 | |
| 929 // Iterate over heap regions, in address order, terminating the | |
| 930 // iteration early if the "doHeapRegion" method returns "true". | |
| 931 void heap_region_iterate(HeapRegionClosure* blk); | |
| 932 | |
| 933 // Iterate over heap regions starting with r (or the first region if "r" | |
| 934 // is NULL), in address order, terminating early if the "doHeapRegion" | |
| 935 // method returns "true". | |
| 936 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk); | |
| 937 | |
| 938 // As above but starting from the region at index idx. | |
| 939 void heap_region_iterate_from(int idx, HeapRegionClosure* blk); | |
| 940 | |
| 941 HeapRegion* region_at(size_t idx); | |
| 942 | |
| 943 // Divide the heap region sequence into "chunks" of some size (the number | |
| 944 // of regions divided by the number of parallel threads times some | |
| 945 // overpartition factor, currently 4). Assumes that this will be called | |
| 946 // in parallel by ParallelGCThreads worker threads with discinct worker | |
| 947 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel | |
| 948 // calls will use the same "claim_value", and that that claim value is | |
| 949 // different from the claim_value of any heap region before the start of | |
| 950 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by | |
| 951 // attempting to claim the first region in each chunk, and, if | |
| 952 // successful, applying the closure to each region in the chunk (and | |
| 953 // setting the claim value of the second and subsequent regions of the | |
| 954 // chunk.) For now requires that "doHeapRegion" always returns "false", | |
| 955 // i.e., that a closure never attempt to abort a traversal. | |
| 956 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, | |
| 957 int worker, | |
| 958 jint claim_value); | |
| 959 | |
| 390 | 960 // It resets all the region claim values to the default. |
| 961 void reset_heap_region_claim_values(); | |
| 962 | |
| 355 | 963 #ifdef ASSERT |
| 964 bool check_heap_region_claim_values(jint claim_value); | |
| 965 #endif // ASSERT | |
| 966 | |
| 342 | 967 // Iterate over the regions (if any) in the current collection set. |
| 968 void collection_set_iterate(HeapRegionClosure* blk); | |
| 969 | |
| 970 // As above but starting from region r | |
| 971 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); | |
| 972 | |
| 973 // Returns the first (lowest address) compactible space in the heap. | |
| 974 virtual CompactibleSpace* first_compactible_space(); | |
| 975 | |
| 976 // A CollectedHeap will contain some number of spaces. This finds the | |
| 977 // space containing a given address, or else returns NULL. | |
| 978 virtual Space* space_containing(const void* addr) const; | |
| 979 | |
| 980 // A G1CollectedHeap will contain some number of heap regions. This | |
| 981 // finds the region containing a given address, or else returns NULL. | |
| 982 HeapRegion* heap_region_containing(const void* addr) const; | |
| 983 | |
| 984 // Like the above, but requires "addr" to be in the heap (to avoid a | |
| 985 // null-check), and unlike the above, may return an continuing humongous | |
| 986 // region. | |
| 987 HeapRegion* heap_region_containing_raw(const void* addr) const; | |
| 988 | |
| 989 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, | |
| 990 // each address in the (reserved) heap is a member of exactly | |
| 991 // one block. The defining characteristic of a block is that it is | |
| 992 // possible to find its size, and thus to progress forward to the next | |
| 993 // block. (Blocks may be of different sizes.) Thus, blocks may | |
| 994 // represent Java objects, or they might be free blocks in a | |
| 995 // free-list-based heap (or subheap), as long as the two kinds are | |
| 996 // distinguishable and the size of each is determinable. | |
| 997 | |
| 998 // Returns the address of the start of the "block" that contains the | |
| 999 // address "addr". We say "blocks" instead of "object" since some heaps | |
| 1000 // may not pack objects densely; a chunk may either be an object or a | |
| 1001 // non-object. | |
| 1002 virtual HeapWord* block_start(const void* addr) const; | |
| 1003 | |
| 1004 // Requires "addr" to be the start of a chunk, and returns its size. | |
| 1005 // "addr + size" is required to be the start of a new chunk, or the end | |
| 1006 // of the active area of the heap. | |
| 1007 virtual size_t block_size(const HeapWord* addr) const; | |
| 1008 | |
| 1009 // Requires "addr" to be the start of a block, and returns "TRUE" iff | |
| 1010 // the block is an object. | |
| 1011 virtual bool block_is_obj(const HeapWord* addr) const; | |
| 1012 | |
| 1013 // Does this heap support heap inspection? (+PrintClassHistogram) | |
| 1014 virtual bool supports_heap_inspection() const { return true; } | |
| 1015 | |
| 1016 // Section on thread-local allocation buffers (TLABs) | |
| 1017 // See CollectedHeap for semantics. | |
| 1018 | |
| 1019 virtual bool supports_tlab_allocation() const; | |
| 1020 virtual size_t tlab_capacity(Thread* thr) const; | |
| 1021 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; | |
| 1022 virtual HeapWord* allocate_new_tlab(size_t size); | |
| 1023 | |
| 1024 // Can a compiler initialize a new object without store barriers? | |
| 1025 // This permission only extends from the creation of a new object | |
| 1026 // via a TLAB up to the first subsequent safepoint. | |
| 1027 virtual bool can_elide_tlab_store_barriers() const { | |
| 1028 // Since G1's TLAB's may, on occasion, come from non-young regions | |
| 1029 // as well. (Is there a flag controlling that? XXX) | |
| 1030 return false; | |
| 1031 } | |
| 1032 | |
| 1033 // Can a compiler elide a store barrier when it writes | |
| 1034 // a permanent oop into the heap? Applies when the compiler | |
| 1035 // is storing x to the heap, where x->is_perm() is true. | |
| 1036 virtual bool can_elide_permanent_oop_store_barriers() const { | |
| 1037 // At least until perm gen collection is also G1-ified, at | |
| 1038 // which point this should return false. | |
| 1039 return true; | |
| 1040 } | |
| 1041 | |
| 1042 virtual bool allocs_are_zero_filled(); | |
| 1043 | |
| 1044 // The boundary between a "large" and "small" array of primitives, in | |
| 1045 // words. | |
| 1046 virtual size_t large_typearray_limit(); | |
| 1047 | |
| 1048 // All popular objects are guaranteed to have addresses below this | |
| 1049 // boundary. | |
| 1050 HeapWord* popular_object_boundary() { | |
| 1051 return _popular_object_boundary; | |
| 1052 } | |
| 1053 | |
| 1054 // Declare the region as one that should be evacuated because its | |
| 1055 // remembered set is too large. | |
| 1056 void schedule_popular_region_evac(HeapRegion* r); | |
| 1057 // If there is a popular region to evacuate it, remove it from the list | |
| 1058 // and return it. | |
| 1059 HeapRegion* popular_region_to_evac(); | |
| 1060 // Evacuate the given popular region. | |
| 1061 void evac_popular_region(HeapRegion* r); | |
| 1062 | |
| 1063 // Returns "true" iff the given word_size is "very large". | |
| 1064 static bool isHumongous(size_t word_size) { | |
| 1065 return word_size >= VeryLargeInWords; | |
| 1066 } | |
| 1067 | |
| 1068 // Update mod union table with the set of dirty cards. | |
| 1069 void updateModUnion(); | |
| 1070 | |
| 1071 // Set the mod union bits corresponding to the given memRegion. Note | |
| 1072 // that this is always a safe operation, since it doesn't clear any | |
| 1073 // bits. | |
| 1074 void markModUnionRange(MemRegion mr); | |
| 1075 | |
| 1076 // Records the fact that a marking phase is no longer in progress. | |
| 1077 void set_marking_complete() { | |
| 1078 _mark_in_progress = false; | |
| 1079 } | |
| 1080 void set_marking_started() { | |
| 1081 _mark_in_progress = true; | |
| 1082 } | |
| 1083 bool mark_in_progress() { | |
| 1084 return _mark_in_progress; | |
| 1085 } | |
| 1086 | |
| 1087 // Print the maximum heap capacity. | |
| 1088 virtual size_t max_capacity() const; | |
| 1089 | |
| 1090 virtual jlong millis_since_last_gc(); | |
| 1091 | |
| 1092 // Perform any cleanup actions necessary before allowing a verification. | |
| 1093 virtual void prepare_for_verify(); | |
| 1094 | |
| 1095 // Perform verification. | |
| 1096 virtual void verify(bool allow_dirty, bool silent); | |
| 1097 virtual void print() const; | |
| 1098 virtual void print_on(outputStream* st) const; | |
| 1099 | |
| 1100 virtual void print_gc_threads_on(outputStream* st) const; | |
| 1101 virtual void gc_threads_do(ThreadClosure* tc) const; | |
| 1102 | |
| 1103 // Override | |
| 1104 void print_tracing_info() const; | |
| 1105 | |
| 1106 // If "addr" is a pointer into the (reserved?) heap, returns a positive | |
| 1107 // number indicating the "arena" within the heap in which "addr" falls. | |
| 1108 // Or else returns 0. | |
| 1109 virtual int addr_to_arena_id(void* addr) const; | |
| 1110 | |
| 1111 // Convenience function to be used in situations where the heap type can be | |
| 1112 // asserted to be this type. | |
| 1113 static G1CollectedHeap* heap(); | |
| 1114 | |
| 1115 void empty_young_list(); | |
| 1116 bool should_set_young_locked(); | |
| 1117 | |
| 1118 void set_region_short_lived_locked(HeapRegion* hr); | |
| 1119 // add appropriate methods for any other surv rate groups | |
| 1120 | |
| 1121 void young_list_rs_length_sampling_init() { | |
| 1122 _young_list->rs_length_sampling_init(); | |
| 1123 } | |
| 1124 bool young_list_rs_length_sampling_more() { | |
| 1125 return _young_list->rs_length_sampling_more(); | |
| 1126 } | |
| 1127 void young_list_rs_length_sampling_next() { | |
| 1128 _young_list->rs_length_sampling_next(); | |
| 1129 } | |
| 1130 size_t young_list_sampled_rs_lengths() { | |
| 1131 return _young_list->sampled_rs_lengths(); | |
| 1132 } | |
| 1133 | |
| 1134 size_t young_list_length() { return _young_list->length(); } | |
| 1135 size_t young_list_scan_only_length() { | |
| 1136 return _young_list->scan_only_length(); } | |
| 1137 | |
| 1138 HeapRegion* pop_region_from_young_list() { | |
| 1139 return _young_list->pop_region(); | |
| 1140 } | |
| 1141 | |
| 1142 HeapRegion* young_list_first_region() { | |
| 1143 return _young_list->first_region(); | |
| 1144 } | |
| 1145 | |
| 1146 // debugging | |
| 1147 bool check_young_list_well_formed() { | |
| 1148 return _young_list->check_list_well_formed(); | |
| 1149 } | |
| 1150 bool check_young_list_empty(bool ignore_scan_only_list, | |
| 1151 bool check_sample = true); | |
| 1152 | |
| 1153 // *** Stuff related to concurrent marking. It's not clear to me that so | |
| 1154 // many of these need to be public. | |
| 1155 | |
| 1156 // The functions below are helper functions that a subclass of | |
| 1157 // "CollectedHeap" can use in the implementation of its virtual | |
| 1158 // functions. | |
| 1159 // This performs a concurrent marking of the live objects in a | |
| 1160 // bitmap off to the side. | |
| 1161 void doConcurrentMark(); | |
| 1162 | |
| 1163 // This is called from the marksweep collector which then does | |
| 1164 // a concurrent mark and verifies that the results agree with | |
| 1165 // the stop the world marking. | |
| 1166 void checkConcurrentMark(); | |
| 1167 void do_sync_mark(); | |
| 1168 | |
| 1169 bool isMarkedPrev(oop obj) const; | |
| 1170 bool isMarkedNext(oop obj) const; | |
| 1171 | |
| 1172 // Determine if an object is dead, given the object and also | |
| 1173 // the region to which the object belongs. An object is dead | |
| 1174 // iff a) it was not allocated since the last mark and b) it | |
| 1175 // is not marked. | |
| 1176 | |
| 1177 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { | |
| 1178 return | |
| 1179 !hr->obj_allocated_since_prev_marking(obj) && | |
| 1180 !isMarkedPrev(obj); | |
| 1181 } | |
| 1182 | |
| 1183 // This is used when copying an object to survivor space. | |
| 1184 // If the object is marked live, then we mark the copy live. | |
| 1185 // If the object is allocated since the start of this mark | |
| 1186 // cycle, then we mark the copy live. | |
| 1187 // If the object has been around since the previous mark | |
| 1188 // phase, and hasn't been marked yet during this phase, | |
| 1189 // then we don't mark it, we just wait for the | |
| 1190 // current marking cycle to get to it. | |
| 1191 | |
| 1192 // This function returns true when an object has been | |
| 1193 // around since the previous marking and hasn't yet | |
| 1194 // been marked during this marking. | |
| 1195 | |
| 1196 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { | |
| 1197 return | |
| 1198 !hr->obj_allocated_since_next_marking(obj) && | |
| 1199 !isMarkedNext(obj); | |
| 1200 } | |
| 1201 | |
| 1202 // Determine if an object is dead, given only the object itself. | |
| 1203 // This will find the region to which the object belongs and | |
| 1204 // then call the region version of the same function. | |
| 1205 | |
| 1206 // Added if it is in permanent gen it isn't dead. | |
| 1207 // Added if it is NULL it isn't dead. | |
| 1208 | |
| 1209 bool is_obj_dead(oop obj) { | |
| 1210 HeapRegion* hr = heap_region_containing(obj); | |
| 1211 if (hr == NULL) { | |
| 1212 if (Universe::heap()->is_in_permanent(obj)) | |
| 1213 return false; | |
| 1214 else if (obj == NULL) return false; | |
| 1215 else return true; | |
| 1216 } | |
| 1217 else return is_obj_dead(obj, hr); | |
| 1218 } | |
| 1219 | |
| 1220 bool is_obj_ill(oop obj) { | |
| 1221 HeapRegion* hr = heap_region_containing(obj); | |
| 1222 if (hr == NULL) { | |
| 1223 if (Universe::heap()->is_in_permanent(obj)) | |
| 1224 return false; | |
| 1225 else if (obj == NULL) return false; | |
| 1226 else return true; | |
| 1227 } | |
| 1228 else return is_obj_ill(obj, hr); | |
| 1229 } | |
| 1230 | |
| 1231 // The following is just to alert the verification code | |
| 1232 // that a full collection has occurred and that the | |
| 1233 // remembered sets are no longer up to date. | |
| 1234 bool _full_collection; | |
| 1235 void set_full_collection() { _full_collection = true;} | |
| 1236 void clear_full_collection() {_full_collection = false;} | |
| 1237 bool full_collection() {return _full_collection;} | |
| 1238 | |
| 1239 ConcurrentMark* concurrent_mark() const { return _cm; } | |
| 1240 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } | |
| 1241 | |
| 1242 public: | |
| 1243 void stop_conc_gc_threads(); | |
| 1244 | |
| 1245 // <NEW PREDICTION> | |
| 1246 | |
| 1247 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young); | |
| 1248 void check_if_region_is_too_expensive(double predicted_time_ms); | |
| 1249 size_t pending_card_num(); | |
| 1250 size_t max_pending_card_num(); | |
| 1251 size_t cards_scanned(); | |
| 1252 | |
| 1253 // </NEW PREDICTION> | |
| 1254 | |
| 1255 protected: | |
| 1256 size_t _max_heap_capacity; | |
| 1257 | |
| 1258 // debug_only(static void check_for_valid_allocation_state();) | |
| 1259 | |
| 1260 public: | |
| 1261 // Temporary: call to mark things unimplemented for the G1 heap (e.g., | |
| 1262 // MemoryService). In productization, we can make this assert false | |
| 1263 // to catch such places (as well as searching for calls to this...) | |
| 1264 static void g1_unimplemented(); | |
| 1265 | |
| 1266 }; | |
| 1267 | |
| 1268 // Local Variables: *** | |
| 1269 // c-indentation-style: gnu *** | |
| 1270 // End: *** |