1 /* 2 * Copyright (c) 2001, 2019, 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 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/g1Allocator.inline.hpp" 32 #include "gc/g1/g1Arguments.hpp" 33 #include "gc/g1/g1BarrierSet.hpp" 34 #include "gc/g1/g1CardTableEntryClosure.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectionSet.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 41 #include "gc/g1/g1DirtyCardQueue.hpp" 42 #include "gc/g1/g1EvacStats.inline.hpp" 43 #include "gc/g1/g1FullCollector.hpp" 44 #include "gc/g1/g1GCPhaseTimes.hpp" 45 #include "gc/g1/g1HeapSizingPolicy.hpp" 46 #include "gc/g1/g1HeapTransition.hpp" 47 #include "gc/g1/g1HeapVerifier.hpp" 48 #include "gc/g1/g1HotCardCache.hpp" 49 #include "gc/g1/g1MemoryPool.hpp" 50 #include "gc/g1/g1OopClosures.inline.hpp" 51 #include "gc/g1/g1ParallelCleaning.hpp" 52 #include "gc/g1/g1ParScanThreadState.inline.hpp" 53 #include "gc/g1/g1Policy.hpp" 54 #include "gc/g1/g1RedirtyCardsQueue.hpp" 55 #include "gc/g1/g1RegionToSpaceMapper.hpp" 56 #include "gc/g1/g1RemSet.hpp" 57 #include "gc/g1/g1RootClosures.hpp" 58 #include "gc/g1/g1RootProcessor.hpp" 59 #include "gc/g1/g1SATBMarkQueueSet.hpp" 60 #include "gc/g1/g1StringDedup.hpp" 61 #include "gc/g1/g1ThreadLocalData.hpp" 62 #include "gc/g1/g1Trace.hpp" 63 #include "gc/g1/g1YCTypes.hpp" 64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 65 #include "gc/g1/g1VMOperations.hpp" 66 #include "gc/g1/heapRegion.inline.hpp" 67 #include "gc/g1/heapRegionRemSet.hpp" 68 #include "gc/g1/heapRegionSet.inline.hpp" 69 #include "gc/shared/gcBehaviours.hpp" 70 #include "gc/shared/gcHeapSummary.hpp" 71 #include "gc/shared/gcId.hpp" 72 #include "gc/shared/gcLocker.hpp" 73 #include "gc/shared/gcTimer.hpp" 74 #include "gc/shared/gcTraceTime.inline.hpp" 75 #include "gc/shared/generationSpec.hpp" 76 #include "gc/shared/isGCActiveMark.hpp" 77 #include "gc/shared/locationPrinter.inline.hpp" 78 #include "gc/shared/oopStorageParState.hpp" 79 #include "gc/shared/preservedMarks.inline.hpp" 80 #include "gc/shared/suspendibleThreadSet.hpp" 81 #include "gc/shared/referenceProcessor.inline.hpp" 82 #include "gc/shared/taskqueue.inline.hpp" 83 #include "gc/shared/weakProcessor.inline.hpp" 84 #include "gc/shared/workerPolicy.hpp" 85 #include "logging/log.hpp" 86 #include "memory/allocation.hpp" 87 #include "memory/iterator.hpp" 88 #include "memory/resourceArea.hpp" 89 #include "memory/universe.hpp" 90 #include "oops/access.inline.hpp" 91 #include "oops/compressedOops.inline.hpp" 92 #include "oops/oop.inline.hpp" 93 #include "runtime/atomic.hpp" 94 #include "runtime/flags/flagSetting.hpp" 95 #include "runtime/handles.inline.hpp" 96 #include "runtime/init.hpp" 97 #include "runtime/orderAccess.hpp" 98 #include "runtime/threadSMR.hpp" 99 #include "runtime/vmThread.hpp" 100 #include "utilities/align.hpp" 101 #include "utilities/globalDefinitions.hpp" 102 #include "utilities/stack.inline.hpp" 103 104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 105 106 // INVARIANTS/NOTES 107 // 108 // All allocation activity covered by the G1CollectedHeap interface is 109 // serialized by acquiring the HeapLock. This happens in mem_allocate 110 // and allocate_new_tlab, which are the "entry" points to the 111 // allocation code from the rest of the JVM. (Note that this does not 112 // apply to TLAB allocation, which is not part of this interface: it 113 // is done by clients of this interface.) 114 115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 116 private: 117 size_t _num_dirtied; 118 G1CollectedHeap* _g1h; 119 G1CardTable* _g1_ct; 120 121 HeapRegion* region_for_card(CardValue* card_ptr) const { 122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 123 } 124 125 bool will_become_free(HeapRegion* hr) const { 126 // A region will be freed by free_collection_set if the region is in the 127 // collection set and has not had an evacuation failure. 128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 129 } 130 131 public: 132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 134 135 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 136 HeapRegion* hr = region_for_card(card_ptr); 137 138 // Should only dirty cards in regions that won't be freed. 139 if (!will_become_free(hr)) { 140 *card_ptr = G1CardTable::dirty_card_val(); 141 _num_dirtied++; 142 } 143 } 144 145 size_t num_dirtied() const { return _num_dirtied; } 146 }; 147 148 149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 151 } 152 153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 154 // The from card cache is not the memory that is actually committed. So we cannot 155 // take advantage of the zero_filled parameter. 156 reset_from_card_cache(start_idx, num_regions); 157 } 158 159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 160 Ticks start = Ticks::now(); 161 workers()->run_task(task, workers()->active_workers()); 162 return Ticks::now() - start; 163 } 164 165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 166 MemRegion mr) { 167 return new HeapRegion(hrs_index, bot(), mr); 168 } 169 170 // Private methods. 171 172 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 173 HeapRegionType type, 174 bool do_expand, 175 uint node_index) { 176 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 177 "the only time we use this to allocate a humongous region is " 178 "when we are allocating a single humongous region"); 179 180 HeapRegion* res = _hrm->allocate_free_region(type, node_index); 181 182 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 183 // Currently, only attempts to allocate GC alloc regions set 184 // do_expand to true. So, we should only reach here during a 185 // safepoint. If this assumption changes we might have to 186 // reconsider the use of _expand_heap_after_alloc_failure. 187 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 188 189 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 190 word_size * HeapWordSize); 191 192 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 193 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 194 word_size * HeapWordSize); 195 if (expand_single_region(node_index)) { 196 // Given that expand_single_region() succeeded in expanding the heap, and we 197 // always expand the heap by an amount aligned to the heap 198 // region size, the free list should in theory not be empty. 199 // In either case allocate_free_region() will check for NULL. 200 res = _hrm->allocate_free_region(type, node_index); 201 } else { 202 _expand_heap_after_alloc_failure = false; 203 } 204 } 205 return res; 206 } 207 208 HeapWord* 209 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 210 uint num_regions, 211 size_t word_size) { 212 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 213 assert(is_humongous(word_size), "word_size should be humongous"); 214 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 215 216 // Index of last region in the series. 217 uint last = first + num_regions - 1; 218 219 // We need to initialize the region(s) we just discovered. This is 220 // a bit tricky given that it can happen concurrently with 221 // refinement threads refining cards on these regions and 222 // potentially wanting to refine the BOT as they are scanning 223 // those cards (this can happen shortly after a cleanup; see CR 224 // 6991377). So we have to set up the region(s) carefully and in 225 // a specific order. 226 227 // The word size sum of all the regions we will allocate. 228 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 229 assert(word_size <= word_size_sum, "sanity"); 230 231 // This will be the "starts humongous" region. 232 HeapRegion* first_hr = region_at(first); 233 // The header of the new object will be placed at the bottom of 234 // the first region. 235 HeapWord* new_obj = first_hr->bottom(); 236 // This will be the new top of the new object. 237 HeapWord* obj_top = new_obj + word_size; 238 239 // First, we need to zero the header of the space that we will be 240 // allocating. When we update top further down, some refinement 241 // threads might try to scan the region. By zeroing the header we 242 // ensure that any thread that will try to scan the region will 243 // come across the zero klass word and bail out. 244 // 245 // NOTE: It would not have been correct to have used 246 // CollectedHeap::fill_with_object() and make the space look like 247 // an int array. The thread that is doing the allocation will 248 // later update the object header to a potentially different array 249 // type and, for a very short period of time, the klass and length 250 // fields will be inconsistent. This could cause a refinement 251 // thread to calculate the object size incorrectly. 252 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 253 254 // Next, pad out the unused tail of the last region with filler 255 // objects, for improved usage accounting. 256 // How many words we use for filler objects. 257 size_t word_fill_size = word_size_sum - word_size; 258 259 // How many words memory we "waste" which cannot hold a filler object. 260 size_t words_not_fillable = 0; 261 262 if (word_fill_size >= min_fill_size()) { 263 fill_with_objects(obj_top, word_fill_size); 264 } else if (word_fill_size > 0) { 265 // We have space to fill, but we cannot fit an object there. 266 words_not_fillable = word_fill_size; 267 word_fill_size = 0; 268 } 269 270 // We will set up the first region as "starts humongous". This 271 // will also update the BOT covering all the regions to reflect 272 // that there is a single object that starts at the bottom of the 273 // first region. 274 first_hr->set_starts_humongous(obj_top, word_fill_size); 275 _policy->remset_tracker()->update_at_allocate(first_hr); 276 // Then, if there are any, we will set up the "continues 277 // humongous" regions. 278 HeapRegion* hr = NULL; 279 for (uint i = first + 1; i <= last; ++i) { 280 hr = region_at(i); 281 hr->set_continues_humongous(first_hr); 282 _policy->remset_tracker()->update_at_allocate(hr); 283 } 284 285 // Up to this point no concurrent thread would have been able to 286 // do any scanning on any region in this series. All the top 287 // fields still point to bottom, so the intersection between 288 // [bottom,top] and [card_start,card_end] will be empty. Before we 289 // update the top fields, we'll do a storestore to make sure that 290 // no thread sees the update to top before the zeroing of the 291 // object header and the BOT initialization. 292 OrderAccess::storestore(); 293 294 // Now, we will update the top fields of the "continues humongous" 295 // regions except the last one. 296 for (uint i = first; i < last; ++i) { 297 hr = region_at(i); 298 hr->set_top(hr->end()); 299 } 300 301 hr = region_at(last); 302 // If we cannot fit a filler object, we must set top to the end 303 // of the humongous object, otherwise we cannot iterate the heap 304 // and the BOT will not be complete. 305 hr->set_top(hr->end() - words_not_fillable); 306 307 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 308 "obj_top should be in last region"); 309 310 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 311 312 assert(words_not_fillable == 0 || 313 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 314 "Miscalculation in humongous allocation"); 315 316 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 317 318 for (uint i = first; i <= last; ++i) { 319 hr = region_at(i); 320 _humongous_set.add(hr); 321 _hr_printer.alloc(hr); 322 } 323 324 return new_obj; 325 } 326 327 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 328 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 329 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 330 } 331 332 // If could fit into free regions w/o expansion, try. 333 // Otherwise, if can expand, do so. 334 // Otherwise, if using ex regions might help, try with ex given back. 335 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 336 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 337 338 _verifier->verify_region_sets_optional(); 339 340 uint first = G1_NO_HRM_INDEX; 341 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 342 343 if (obj_regions == 1) { 344 // Only one region to allocate, try to use a fast path by directly allocating 345 // from the free lists. Do not try to expand here, we will potentially do that 346 // later. 347 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 348 if (hr != NULL) { 349 first = hr->hrm_index(); 350 } 351 } else { 352 // Policy: Try only empty regions (i.e. already committed first). Maybe we 353 // are lucky enough to find some. 354 first = _hrm->find_contiguous_only_empty(obj_regions); 355 if (first != G1_NO_HRM_INDEX) { 356 _hrm->allocate_free_regions_starting_at(first, obj_regions); 357 } 358 } 359 360 if (first == G1_NO_HRM_INDEX) { 361 // Policy: We could not find enough regions for the humongous object in the 362 // free list. Look through the heap to find a mix of free and uncommitted regions. 363 // If so, try expansion. 364 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 365 if (first != G1_NO_HRM_INDEX) { 366 // We found something. Make sure these regions are committed, i.e. expand 367 // the heap. Alternatively we could do a defragmentation GC. 368 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 369 word_size * HeapWordSize); 370 371 _hrm->expand_at(first, obj_regions, workers()); 372 policy()->record_new_heap_size(num_regions()); 373 374 #ifdef ASSERT 375 for (uint i = first; i < first + obj_regions; ++i) { 376 HeapRegion* hr = region_at(i); 377 assert(hr->is_free(), "sanity"); 378 assert(hr->is_empty(), "sanity"); 379 assert(is_on_master_free_list(hr), "sanity"); 380 } 381 #endif 382 _hrm->allocate_free_regions_starting_at(first, obj_regions); 383 } else { 384 // Policy: Potentially trigger a defragmentation GC. 385 } 386 } 387 388 HeapWord* result = NULL; 389 if (first != G1_NO_HRM_INDEX) { 390 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 391 assert(result != NULL, "it should always return a valid result"); 392 393 // A successful humongous object allocation changes the used space 394 // information of the old generation so we need to recalculate the 395 // sizes and update the jstat counters here. 396 g1mm()->update_sizes(); 397 } 398 399 _verifier->verify_region_sets_optional(); 400 401 return result; 402 } 403 404 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 405 size_t requested_size, 406 size_t* actual_size) { 407 assert_heap_not_locked_and_not_at_safepoint(); 408 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 409 410 return attempt_allocation(min_size, requested_size, actual_size); 411 } 412 413 HeapWord* 414 G1CollectedHeap::mem_allocate(size_t word_size, 415 bool* gc_overhead_limit_was_exceeded) { 416 assert_heap_not_locked_and_not_at_safepoint(); 417 418 if (is_humongous(word_size)) { 419 return attempt_allocation_humongous(word_size); 420 } 421 size_t dummy = 0; 422 return attempt_allocation(word_size, word_size, &dummy); 423 } 424 425 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 426 ResourceMark rm; // For retrieving the thread names in log messages. 427 428 // Make sure you read the note in attempt_allocation_humongous(). 429 430 assert_heap_not_locked_and_not_at_safepoint(); 431 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 432 "be called for humongous allocation requests"); 433 434 // We should only get here after the first-level allocation attempt 435 // (attempt_allocation()) failed to allocate. 436 437 // We will loop until a) we manage to successfully perform the 438 // allocation or b) we successfully schedule a collection which 439 // fails to perform the allocation. b) is the only case when we'll 440 // return NULL. 441 HeapWord* result = NULL; 442 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 443 bool should_try_gc; 444 uint gc_count_before; 445 446 { 447 MutexLocker x(Heap_lock); 448 result = _allocator->attempt_allocation_locked(word_size); 449 if (result != NULL) { 450 return result; 451 } 452 453 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 454 // This is different to when only GCLocker::needs_gc() is set: try to avoid 455 // waiting because the GCLocker is active to not wait too long. 456 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 457 // No need for an ergo message here, can_expand_young_list() does this when 458 // it returns true. 459 result = _allocator->attempt_allocation_force(word_size); 460 if (result != NULL) { 461 return result; 462 } 463 } 464 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 465 // the GCLocker initiated GC has been performed and then retry. This includes 466 // the case when the GC Locker is not active but has not been performed. 467 should_try_gc = !GCLocker::needs_gc(); 468 // Read the GC count while still holding the Heap_lock. 469 gc_count_before = total_collections(); 470 } 471 472 if (should_try_gc) { 473 bool succeeded; 474 result = do_collection_pause(word_size, gc_count_before, &succeeded, 475 GCCause::_g1_inc_collection_pause); 476 if (result != NULL) { 477 assert(succeeded, "only way to get back a non-NULL result"); 478 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 479 Thread::current()->name(), p2i(result)); 480 return result; 481 } 482 483 if (succeeded) { 484 // We successfully scheduled a collection which failed to allocate. No 485 // point in trying to allocate further. We'll just return NULL. 486 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 487 SIZE_FORMAT " words", Thread::current()->name(), word_size); 488 return NULL; 489 } 490 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 491 Thread::current()->name(), word_size); 492 } else { 493 // Failed to schedule a collection. 494 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 495 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 496 SIZE_FORMAT " words", Thread::current()->name(), word_size); 497 return NULL; 498 } 499 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 500 // The GCLocker is either active or the GCLocker initiated 501 // GC has not yet been performed. Stall until it is and 502 // then retry the allocation. 503 GCLocker::stall_until_clear(); 504 gclocker_retry_count += 1; 505 } 506 507 // We can reach here if we were unsuccessful in scheduling a 508 // collection (because another thread beat us to it) or if we were 509 // stalled due to the GC locker. In either can we should retry the 510 // allocation attempt in case another thread successfully 511 // performed a collection and reclaimed enough space. We do the 512 // first attempt (without holding the Heap_lock) here and the 513 // follow-on attempt will be at the start of the next loop 514 // iteration (after taking the Heap_lock). 515 size_t dummy = 0; 516 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 517 if (result != NULL) { 518 return result; 519 } 520 521 // Give a warning if we seem to be looping forever. 522 if ((QueuedAllocationWarningCount > 0) && 523 (try_count % QueuedAllocationWarningCount == 0)) { 524 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 525 Thread::current()->name(), try_count, word_size); 526 } 527 } 528 529 ShouldNotReachHere(); 530 return NULL; 531 } 532 533 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 534 assert_at_safepoint_on_vm_thread(); 535 if (_archive_allocator == NULL) { 536 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 537 } 538 } 539 540 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 541 // Allocations in archive regions cannot be of a size that would be considered 542 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 543 // may be different at archive-restore time. 544 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 545 } 546 547 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 548 assert_at_safepoint_on_vm_thread(); 549 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 550 if (is_archive_alloc_too_large(word_size)) { 551 return NULL; 552 } 553 return _archive_allocator->archive_mem_allocate(word_size); 554 } 555 556 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 557 size_t end_alignment_in_bytes) { 558 assert_at_safepoint_on_vm_thread(); 559 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 560 561 // Call complete_archive to do the real work, filling in the MemRegion 562 // array with the archive regions. 563 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 564 delete _archive_allocator; 565 _archive_allocator = NULL; 566 } 567 568 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 569 assert(ranges != NULL, "MemRegion array NULL"); 570 assert(count != 0, "No MemRegions provided"); 571 MemRegion reserved = _hrm->reserved(); 572 for (size_t i = 0; i < count; i++) { 573 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 574 return false; 575 } 576 } 577 return true; 578 } 579 580 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 581 size_t count, 582 bool open) { 583 assert(!is_init_completed(), "Expect to be called at JVM init time"); 584 assert(ranges != NULL, "MemRegion array NULL"); 585 assert(count != 0, "No MemRegions provided"); 586 MutexLocker x(Heap_lock); 587 588 MemRegion reserved = _hrm->reserved(); 589 HeapWord* prev_last_addr = NULL; 590 HeapRegion* prev_last_region = NULL; 591 592 // Temporarily disable pretouching of heap pages. This interface is used 593 // when mmap'ing archived heap data in, so pre-touching is wasted. 594 FlagSetting fs(AlwaysPreTouch, false); 595 596 // Enable archive object checking used by G1MarkSweep. We have to let it know 597 // about each archive range, so that objects in those ranges aren't marked. 598 G1ArchiveAllocator::enable_archive_object_check(); 599 600 // For each specified MemRegion range, allocate the corresponding G1 601 // regions and mark them as archive regions. We expect the ranges 602 // in ascending starting address order, without overlap. 603 for (size_t i = 0; i < count; i++) { 604 MemRegion curr_range = ranges[i]; 605 HeapWord* start_address = curr_range.start(); 606 size_t word_size = curr_range.word_size(); 607 HeapWord* last_address = curr_range.last(); 608 size_t commits = 0; 609 610 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 611 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 612 p2i(start_address), p2i(last_address)); 613 guarantee(start_address > prev_last_addr, 614 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 615 p2i(start_address), p2i(prev_last_addr)); 616 prev_last_addr = last_address; 617 618 // Check for ranges that start in the same G1 region in which the previous 619 // range ended, and adjust the start address so we don't try to allocate 620 // the same region again. If the current range is entirely within that 621 // region, skip it, just adjusting the recorded top. 622 HeapRegion* start_region = _hrm->addr_to_region(start_address); 623 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 624 start_address = start_region->end(); 625 if (start_address > last_address) { 626 increase_used(word_size * HeapWordSize); 627 start_region->set_top(last_address + 1); 628 continue; 629 } 630 start_region->set_top(start_address); 631 curr_range = MemRegion(start_address, last_address + 1); 632 start_region = _hrm->addr_to_region(start_address); 633 } 634 635 // Perform the actual region allocation, exiting if it fails. 636 // Then note how much new space we have allocated. 637 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 638 return false; 639 } 640 increase_used(word_size * HeapWordSize); 641 if (commits != 0) { 642 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 643 HeapRegion::GrainWords * HeapWordSize * commits); 644 645 } 646 647 // Mark each G1 region touched by the range as archive, add it to 648 // the old set, and set top. 649 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 650 HeapRegion* last_region = _hrm->addr_to_region(last_address); 651 prev_last_region = last_region; 652 653 while (curr_region != NULL) { 654 assert(curr_region->is_empty() && !curr_region->is_pinned(), 655 "Region already in use (index %u)", curr_region->hrm_index()); 656 if (open) { 657 curr_region->set_open_archive(); 658 } else { 659 curr_region->set_closed_archive(); 660 } 661 _hr_printer.alloc(curr_region); 662 _archive_set.add(curr_region); 663 HeapWord* top; 664 HeapRegion* next_region; 665 if (curr_region != last_region) { 666 top = curr_region->end(); 667 next_region = _hrm->next_region_in_heap(curr_region); 668 } else { 669 top = last_address + 1; 670 next_region = NULL; 671 } 672 curr_region->set_top(top); 673 curr_region->set_first_dead(top); 674 curr_region->set_end_of_live(top); 675 curr_region = next_region; 676 } 677 678 // Notify mark-sweep of the archive 679 G1ArchiveAllocator::set_range_archive(curr_range, open); 680 } 681 return true; 682 } 683 684 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 685 assert(!is_init_completed(), "Expect to be called at JVM init time"); 686 assert(ranges != NULL, "MemRegion array NULL"); 687 assert(count != 0, "No MemRegions provided"); 688 MemRegion reserved = _hrm->reserved(); 689 HeapWord *prev_last_addr = NULL; 690 HeapRegion* prev_last_region = NULL; 691 692 // For each MemRegion, create filler objects, if needed, in the G1 regions 693 // that contain the address range. The address range actually within the 694 // MemRegion will not be modified. That is assumed to have been initialized 695 // elsewhere, probably via an mmap of archived heap data. 696 MutexLocker x(Heap_lock); 697 for (size_t i = 0; i < count; i++) { 698 HeapWord* start_address = ranges[i].start(); 699 HeapWord* last_address = ranges[i].last(); 700 701 assert(reserved.contains(start_address) && reserved.contains(last_address), 702 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 703 p2i(start_address), p2i(last_address)); 704 assert(start_address > prev_last_addr, 705 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 706 p2i(start_address), p2i(prev_last_addr)); 707 708 HeapRegion* start_region = _hrm->addr_to_region(start_address); 709 HeapRegion* last_region = _hrm->addr_to_region(last_address); 710 HeapWord* bottom_address = start_region->bottom(); 711 712 // Check for a range beginning in the same region in which the 713 // previous one ended. 714 if (start_region == prev_last_region) { 715 bottom_address = prev_last_addr + 1; 716 } 717 718 // Verify that the regions were all marked as archive regions by 719 // alloc_archive_regions. 720 HeapRegion* curr_region = start_region; 721 while (curr_region != NULL) { 722 guarantee(curr_region->is_archive(), 723 "Expected archive region at index %u", curr_region->hrm_index()); 724 if (curr_region != last_region) { 725 curr_region = _hrm->next_region_in_heap(curr_region); 726 } else { 727 curr_region = NULL; 728 } 729 } 730 731 prev_last_addr = last_address; 732 prev_last_region = last_region; 733 734 // Fill the memory below the allocated range with dummy object(s), 735 // if the region bottom does not match the range start, or if the previous 736 // range ended within the same G1 region, and there is a gap. 737 if (start_address != bottom_address) { 738 size_t fill_size = pointer_delta(start_address, bottom_address); 739 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 740 increase_used(fill_size * HeapWordSize); 741 } 742 } 743 } 744 745 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 746 size_t desired_word_size, 747 size_t* actual_word_size) { 748 assert_heap_not_locked_and_not_at_safepoint(); 749 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 750 "be called for humongous allocation requests"); 751 752 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 753 754 if (result == NULL) { 755 *actual_word_size = desired_word_size; 756 result = attempt_allocation_slow(desired_word_size); 757 } 758 759 assert_heap_not_locked(); 760 if (result != NULL) { 761 assert(*actual_word_size != 0, "Actual size must have been set here"); 762 dirty_young_block(result, *actual_word_size); 763 } else { 764 *actual_word_size = 0; 765 } 766 767 return result; 768 } 769 770 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 771 assert(!is_init_completed(), "Expect to be called at JVM init time"); 772 assert(ranges != NULL, "MemRegion array NULL"); 773 assert(count != 0, "No MemRegions provided"); 774 MemRegion reserved = _hrm->reserved(); 775 HeapWord* prev_last_addr = NULL; 776 HeapRegion* prev_last_region = NULL; 777 size_t size_used = 0; 778 size_t uncommitted_regions = 0; 779 780 // For each Memregion, free the G1 regions that constitute it, and 781 // notify mark-sweep that the range is no longer to be considered 'archive.' 782 MutexLocker x(Heap_lock); 783 for (size_t i = 0; i < count; i++) { 784 HeapWord* start_address = ranges[i].start(); 785 HeapWord* last_address = ranges[i].last(); 786 787 assert(reserved.contains(start_address) && reserved.contains(last_address), 788 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 789 p2i(start_address), p2i(last_address)); 790 assert(start_address > prev_last_addr, 791 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 792 p2i(start_address), p2i(prev_last_addr)); 793 size_used += ranges[i].byte_size(); 794 prev_last_addr = last_address; 795 796 HeapRegion* start_region = _hrm->addr_to_region(start_address); 797 HeapRegion* last_region = _hrm->addr_to_region(last_address); 798 799 // Check for ranges that start in the same G1 region in which the previous 800 // range ended, and adjust the start address so we don't try to free 801 // the same region again. If the current range is entirely within that 802 // region, skip it. 803 if (start_region == prev_last_region) { 804 start_address = start_region->end(); 805 if (start_address > last_address) { 806 continue; 807 } 808 start_region = _hrm->addr_to_region(start_address); 809 } 810 prev_last_region = last_region; 811 812 // After verifying that each region was marked as an archive region by 813 // alloc_archive_regions, set it free and empty and uncommit it. 814 HeapRegion* curr_region = start_region; 815 while (curr_region != NULL) { 816 guarantee(curr_region->is_archive(), 817 "Expected archive region at index %u", curr_region->hrm_index()); 818 uint curr_index = curr_region->hrm_index(); 819 _archive_set.remove(curr_region); 820 curr_region->set_free(); 821 curr_region->set_top(curr_region->bottom()); 822 if (curr_region != last_region) { 823 curr_region = _hrm->next_region_in_heap(curr_region); 824 } else { 825 curr_region = NULL; 826 } 827 _hrm->shrink_at(curr_index, 1); 828 uncommitted_regions++; 829 } 830 831 // Notify mark-sweep that this is no longer an archive range. 832 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 833 } 834 835 if (uncommitted_regions != 0) { 836 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 837 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 838 } 839 decrease_used(size_used); 840 } 841 842 oop G1CollectedHeap::materialize_archived_object(oop obj) { 843 assert(obj != NULL, "archived obj is NULL"); 844 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 845 846 // Loading an archived object makes it strongly reachable. If it is 847 // loaded during concurrent marking, it must be enqueued to the SATB 848 // queue, shading the previously white object gray. 849 G1BarrierSet::enqueue(obj); 850 851 return obj; 852 } 853 854 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 855 ResourceMark rm; // For retrieving the thread names in log messages. 856 857 // The structure of this method has a lot of similarities to 858 // attempt_allocation_slow(). The reason these two were not merged 859 // into a single one is that such a method would require several "if 860 // allocation is not humongous do this, otherwise do that" 861 // conditional paths which would obscure its flow. In fact, an early 862 // version of this code did use a unified method which was harder to 863 // follow and, as a result, it had subtle bugs that were hard to 864 // track down. So keeping these two methods separate allows each to 865 // be more readable. It will be good to keep these two in sync as 866 // much as possible. 867 868 assert_heap_not_locked_and_not_at_safepoint(); 869 assert(is_humongous(word_size), "attempt_allocation_humongous() " 870 "should only be called for humongous allocations"); 871 872 // Humongous objects can exhaust the heap quickly, so we should check if we 873 // need to start a marking cycle at each humongous object allocation. We do 874 // the check before we do the actual allocation. The reason for doing it 875 // before the allocation is that we avoid having to keep track of the newly 876 // allocated memory while we do a GC. 877 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 878 word_size)) { 879 collect(GCCause::_g1_humongous_allocation); 880 } 881 882 // We will loop until a) we manage to successfully perform the 883 // allocation or b) we successfully schedule a collection which 884 // fails to perform the allocation. b) is the only case when we'll 885 // return NULL. 886 HeapWord* result = NULL; 887 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 888 bool should_try_gc; 889 uint gc_count_before; 890 891 892 { 893 MutexLocker x(Heap_lock); 894 895 // Given that humongous objects are not allocated in young 896 // regions, we'll first try to do the allocation without doing a 897 // collection hoping that there's enough space in the heap. 898 result = humongous_obj_allocate(word_size); 899 if (result != NULL) { 900 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 901 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 902 return result; 903 } 904 905 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 906 // the GCLocker initiated GC has been performed and then retry. This includes 907 // the case when the GC Locker is not active but has not been performed. 908 should_try_gc = !GCLocker::needs_gc(); 909 // Read the GC count while still holding the Heap_lock. 910 gc_count_before = total_collections(); 911 } 912 913 if (should_try_gc) { 914 bool succeeded; 915 result = do_collection_pause(word_size, gc_count_before, &succeeded, 916 GCCause::_g1_humongous_allocation); 917 if (result != NULL) { 918 assert(succeeded, "only way to get back a non-NULL result"); 919 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 920 Thread::current()->name(), p2i(result)); 921 return result; 922 } 923 924 if (succeeded) { 925 // We successfully scheduled a collection which failed to allocate. No 926 // point in trying to allocate further. We'll just return NULL. 927 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 928 SIZE_FORMAT " words", Thread::current()->name(), word_size); 929 return NULL; 930 } 931 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 932 Thread::current()->name(), word_size); 933 } else { 934 // Failed to schedule a collection. 935 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 936 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 937 SIZE_FORMAT " words", Thread::current()->name(), word_size); 938 return NULL; 939 } 940 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 941 // The GCLocker is either active or the GCLocker initiated 942 // GC has not yet been performed. Stall until it is and 943 // then retry the allocation. 944 GCLocker::stall_until_clear(); 945 gclocker_retry_count += 1; 946 } 947 948 949 // We can reach here if we were unsuccessful in scheduling a 950 // collection (because another thread beat us to it) or if we were 951 // stalled due to the GC locker. In either can we should retry the 952 // allocation attempt in case another thread successfully 953 // performed a collection and reclaimed enough space. 954 // Humongous object allocation always needs a lock, so we wait for the retry 955 // in the next iteration of the loop, unlike for the regular iteration case. 956 // Give a warning if we seem to be looping forever. 957 958 if ((QueuedAllocationWarningCount > 0) && 959 (try_count % QueuedAllocationWarningCount == 0)) { 960 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 961 Thread::current()->name(), try_count, word_size); 962 } 963 } 964 965 ShouldNotReachHere(); 966 return NULL; 967 } 968 969 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 970 bool expect_null_mutator_alloc_region) { 971 assert_at_safepoint_on_vm_thread(); 972 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 973 "the current alloc region was unexpectedly found to be non-NULL"); 974 975 if (!is_humongous(word_size)) { 976 return _allocator->attempt_allocation_locked(word_size); 977 } else { 978 HeapWord* result = humongous_obj_allocate(word_size); 979 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 980 collector_state()->set_initiate_conc_mark_if_possible(true); 981 } 982 return result; 983 } 984 985 ShouldNotReachHere(); 986 } 987 988 class PostCompactionPrinterClosure: public HeapRegionClosure { 989 private: 990 G1HRPrinter* _hr_printer; 991 public: 992 bool do_heap_region(HeapRegion* hr) { 993 assert(!hr->is_young(), "not expecting to find young regions"); 994 _hr_printer->post_compaction(hr); 995 return false; 996 } 997 998 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 999 : _hr_printer(hr_printer) { } 1000 }; 1001 1002 void G1CollectedHeap::print_hrm_post_compaction() { 1003 if (_hr_printer.is_active()) { 1004 PostCompactionPrinterClosure cl(hr_printer()); 1005 heap_region_iterate(&cl); 1006 } 1007 } 1008 1009 void G1CollectedHeap::abort_concurrent_cycle() { 1010 // If we start the compaction before the CM threads finish 1011 // scanning the root regions we might trip them over as we'll 1012 // be moving objects / updating references. So let's wait until 1013 // they are done. By telling them to abort, they should complete 1014 // early. 1015 _cm->root_regions()->abort(); 1016 _cm->root_regions()->wait_until_scan_finished(); 1017 1018 // Disable discovery and empty the discovered lists 1019 // for the CM ref processor. 1020 _ref_processor_cm->disable_discovery(); 1021 _ref_processor_cm->abandon_partial_discovery(); 1022 _ref_processor_cm->verify_no_references_recorded(); 1023 1024 // Abandon current iterations of concurrent marking and concurrent 1025 // refinement, if any are in progress. 1026 concurrent_mark()->concurrent_cycle_abort(); 1027 } 1028 1029 void G1CollectedHeap::prepare_heap_for_full_collection() { 1030 // Make sure we'll choose a new allocation region afterwards. 1031 _allocator->release_mutator_alloc_regions(); 1032 _allocator->abandon_gc_alloc_regions(); 1033 1034 // We may have added regions to the current incremental collection 1035 // set between the last GC or pause and now. We need to clear the 1036 // incremental collection set and then start rebuilding it afresh 1037 // after this full GC. 1038 abandon_collection_set(collection_set()); 1039 1040 tear_down_region_sets(false /* free_list_only */); 1041 1042 hrm()->prepare_for_full_collection_start(); 1043 } 1044 1045 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1046 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1047 assert_used_and_recalculate_used_equal(this); 1048 _verifier->verify_region_sets_optional(); 1049 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1050 _verifier->check_bitmaps("Full GC Start"); 1051 } 1052 1053 void G1CollectedHeap::prepare_heap_for_mutators() { 1054 hrm()->prepare_for_full_collection_end(); 1055 1056 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1057 ClassLoaderDataGraph::purge(); 1058 MetaspaceUtils::verify_metrics(); 1059 1060 // Prepare heap for normal collections. 1061 assert(num_free_regions() == 0, "we should not have added any free regions"); 1062 rebuild_region_sets(false /* free_list_only */); 1063 abort_refinement(); 1064 resize_heap_if_necessary(); 1065 1066 // Rebuild the strong code root lists for each region 1067 rebuild_strong_code_roots(); 1068 1069 // Purge code root memory 1070 purge_code_root_memory(); 1071 1072 // Start a new incremental collection set for the next pause 1073 start_new_collection_set(); 1074 1075 _allocator->init_mutator_alloc_regions(); 1076 1077 // Post collection state updates. 1078 MetaspaceGC::compute_new_size(); 1079 } 1080 1081 void G1CollectedHeap::abort_refinement() { 1082 if (_hot_card_cache->use_cache()) { 1083 _hot_card_cache->reset_hot_cache(); 1084 } 1085 1086 // Discard all remembered set updates. 1087 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1088 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1089 "DCQS should be empty"); 1090 } 1091 1092 void G1CollectedHeap::verify_after_full_collection() { 1093 _hrm->verify_optional(); 1094 _verifier->verify_region_sets_optional(); 1095 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1096 // Clear the previous marking bitmap, if needed for bitmap verification. 1097 // Note we cannot do this when we clear the next marking bitmap in 1098 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1099 // objects marked during a full GC against the previous bitmap. 1100 // But we need to clear it before calling check_bitmaps below since 1101 // the full GC has compacted objects and updated TAMS but not updated 1102 // the prev bitmap. 1103 if (G1VerifyBitmaps) { 1104 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1105 _cm->clear_prev_bitmap(workers()); 1106 } 1107 // This call implicitly verifies that the next bitmap is clear after Full GC. 1108 _verifier->check_bitmaps("Full GC End"); 1109 1110 // At this point there should be no regions in the 1111 // entire heap tagged as young. 1112 assert(check_young_list_empty(), "young list should be empty at this point"); 1113 1114 // Note: since we've just done a full GC, concurrent 1115 // marking is no longer active. Therefore we need not 1116 // re-enable reference discovery for the CM ref processor. 1117 // That will be done at the start of the next marking cycle. 1118 // We also know that the STW processor should no longer 1119 // discover any new references. 1120 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1121 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1122 _ref_processor_stw->verify_no_references_recorded(); 1123 _ref_processor_cm->verify_no_references_recorded(); 1124 } 1125 1126 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1127 // Post collection logging. 1128 // We should do this after we potentially resize the heap so 1129 // that all the COMMIT / UNCOMMIT events are generated before 1130 // the compaction events. 1131 print_hrm_post_compaction(); 1132 heap_transition->print(); 1133 print_heap_after_gc(); 1134 print_heap_regions(); 1135 #ifdef TRACESPINNING 1136 ParallelTaskTerminator::print_termination_counts(); 1137 #endif 1138 } 1139 1140 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1141 bool clear_all_soft_refs) { 1142 assert_at_safepoint_on_vm_thread(); 1143 1144 if (GCLocker::check_active_before_gc()) { 1145 // Full GC was not completed. 1146 return false; 1147 } 1148 1149 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1150 soft_ref_policy()->should_clear_all_soft_refs(); 1151 1152 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1153 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1154 1155 collector.prepare_collection(); 1156 collector.collect(); 1157 collector.complete_collection(); 1158 1159 // Full collection was successfully completed. 1160 return true; 1161 } 1162 1163 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1164 // Currently, there is no facility in the do_full_collection(bool) API to notify 1165 // the caller that the collection did not succeed (e.g., because it was locked 1166 // out by the GC locker). So, right now, we'll ignore the return value. 1167 bool dummy = do_full_collection(true, /* explicit_gc */ 1168 clear_all_soft_refs); 1169 } 1170 1171 void G1CollectedHeap::resize_heap_if_necessary() { 1172 assert_at_safepoint_on_vm_thread(); 1173 1174 // Capacity, free and used after the GC counted as full regions to 1175 // include the waste in the following calculations. 1176 const size_t capacity_after_gc = capacity(); 1177 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1178 1179 // This is enforced in arguments.cpp. 1180 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1181 "otherwise the code below doesn't make sense"); 1182 1183 // We don't have floating point command-line arguments 1184 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1185 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1186 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1187 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1188 1189 // We have to be careful here as these two calculations can overflow 1190 // 32-bit size_t's. 1191 double used_after_gc_d = (double) used_after_gc; 1192 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1193 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1194 1195 // Let's make sure that they are both under the max heap size, which 1196 // by default will make them fit into a size_t. 1197 double desired_capacity_upper_bound = (double) MaxHeapSize; 1198 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1199 desired_capacity_upper_bound); 1200 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1201 desired_capacity_upper_bound); 1202 1203 // We can now safely turn them into size_t's. 1204 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1205 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1206 1207 // This assert only makes sense here, before we adjust them 1208 // with respect to the min and max heap size. 1209 assert(minimum_desired_capacity <= maximum_desired_capacity, 1210 "minimum_desired_capacity = " SIZE_FORMAT ", " 1211 "maximum_desired_capacity = " SIZE_FORMAT, 1212 minimum_desired_capacity, maximum_desired_capacity); 1213 1214 // Should not be greater than the heap max size. No need to adjust 1215 // it with respect to the heap min size as it's a lower bound (i.e., 1216 // we'll try to make the capacity larger than it, not smaller). 1217 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1218 // Should not be less than the heap min size. No need to adjust it 1219 // with respect to the heap max size as it's an upper bound (i.e., 1220 // we'll try to make the capacity smaller than it, not greater). 1221 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1222 1223 if (capacity_after_gc < minimum_desired_capacity) { 1224 // Don't expand unless it's significant 1225 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1226 1227 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1228 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1229 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1230 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1231 1232 expand(expand_bytes, _workers); 1233 1234 // No expansion, now see if we want to shrink 1235 } else if (capacity_after_gc > maximum_desired_capacity) { 1236 // Capacity too large, compute shrinking size 1237 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1238 1239 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1240 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1241 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1242 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1243 1244 shrink(shrink_bytes); 1245 } 1246 } 1247 1248 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1249 bool do_gc, 1250 bool clear_all_soft_refs, 1251 bool expect_null_mutator_alloc_region, 1252 bool* gc_succeeded) { 1253 *gc_succeeded = true; 1254 // Let's attempt the allocation first. 1255 HeapWord* result = 1256 attempt_allocation_at_safepoint(word_size, 1257 expect_null_mutator_alloc_region); 1258 if (result != NULL) { 1259 return result; 1260 } 1261 1262 // In a G1 heap, we're supposed to keep allocation from failing by 1263 // incremental pauses. Therefore, at least for now, we'll favor 1264 // expansion over collection. (This might change in the future if we can 1265 // do something smarter than full collection to satisfy a failed alloc.) 1266 result = expand_and_allocate(word_size); 1267 if (result != NULL) { 1268 return result; 1269 } 1270 1271 if (do_gc) { 1272 // Expansion didn't work, we'll try to do a Full GC. 1273 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1274 clear_all_soft_refs); 1275 } 1276 1277 return NULL; 1278 } 1279 1280 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1281 bool* succeeded) { 1282 assert_at_safepoint_on_vm_thread(); 1283 1284 // Attempts to allocate followed by Full GC. 1285 HeapWord* result = 1286 satisfy_failed_allocation_helper(word_size, 1287 true, /* do_gc */ 1288 false, /* clear_all_soft_refs */ 1289 false, /* expect_null_mutator_alloc_region */ 1290 succeeded); 1291 1292 if (result != NULL || !*succeeded) { 1293 return result; 1294 } 1295 1296 // Attempts to allocate followed by Full GC that will collect all soft references. 1297 result = satisfy_failed_allocation_helper(word_size, 1298 true, /* do_gc */ 1299 true, /* clear_all_soft_refs */ 1300 true, /* expect_null_mutator_alloc_region */ 1301 succeeded); 1302 1303 if (result != NULL || !*succeeded) { 1304 return result; 1305 } 1306 1307 // Attempts to allocate, no GC 1308 result = satisfy_failed_allocation_helper(word_size, 1309 false, /* do_gc */ 1310 false, /* clear_all_soft_refs */ 1311 true, /* expect_null_mutator_alloc_region */ 1312 succeeded); 1313 1314 if (result != NULL) { 1315 return result; 1316 } 1317 1318 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1319 "Flag should have been handled and cleared prior to this point"); 1320 1321 // What else? We might try synchronous finalization later. If the total 1322 // space available is large enough for the allocation, then a more 1323 // complete compaction phase than we've tried so far might be 1324 // appropriate. 1325 return NULL; 1326 } 1327 1328 // Attempting to expand the heap sufficiently 1329 // to support an allocation of the given "word_size". If 1330 // successful, perform the allocation and return the address of the 1331 // allocated block, or else "NULL". 1332 1333 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1334 assert_at_safepoint_on_vm_thread(); 1335 1336 _verifier->verify_region_sets_optional(); 1337 1338 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1339 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1340 word_size * HeapWordSize); 1341 1342 1343 if (expand(expand_bytes, _workers)) { 1344 _hrm->verify_optional(); 1345 _verifier->verify_region_sets_optional(); 1346 return attempt_allocation_at_safepoint(word_size, 1347 false /* expect_null_mutator_alloc_region */); 1348 } 1349 return NULL; 1350 } 1351 1352 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1353 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1354 aligned_expand_bytes = align_up(aligned_expand_bytes, 1355 HeapRegion::GrainBytes); 1356 1357 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1358 expand_bytes, aligned_expand_bytes); 1359 1360 if (is_maximal_no_gc()) { 1361 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1362 return false; 1363 } 1364 1365 double expand_heap_start_time_sec = os::elapsedTime(); 1366 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1367 assert(regions_to_expand > 0, "Must expand by at least one region"); 1368 1369 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1370 if (expand_time_ms != NULL) { 1371 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1372 } 1373 1374 if (expanded_by > 0) { 1375 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1376 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1377 policy()->record_new_heap_size(num_regions()); 1378 } else { 1379 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1380 1381 // The expansion of the virtual storage space was unsuccessful. 1382 // Let's see if it was because we ran out of swap. 1383 if (G1ExitOnExpansionFailure && 1384 _hrm->available() >= regions_to_expand) { 1385 // We had head room... 1386 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1387 } 1388 } 1389 return regions_to_expand > 0; 1390 } 1391 1392 bool G1CollectedHeap::expand_single_region(uint node_index) { 1393 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1394 1395 if (expanded_by == 0) { 1396 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1398 return false; 1399 } 1400 1401 policy()->record_new_heap_size(num_regions()); 1402 return true; 1403 } 1404 1405 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1406 size_t aligned_shrink_bytes = 1407 ReservedSpace::page_align_size_down(shrink_bytes); 1408 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1409 HeapRegion::GrainBytes); 1410 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1411 1412 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1413 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1414 1415 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B", 1416 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1417 if (num_regions_removed > 0) { 1418 policy()->record_new_heap_size(num_regions()); 1419 } else { 1420 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1421 } 1422 } 1423 1424 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1425 _verifier->verify_region_sets_optional(); 1426 1427 // We should only reach here at the end of a Full GC or during Remark which 1428 // means we should not not be holding to any GC alloc regions. The method 1429 // below will make sure of that and do any remaining clean up. 1430 _allocator->abandon_gc_alloc_regions(); 1431 1432 // Instead of tearing down / rebuilding the free lists here, we 1433 // could instead use the remove_all_pending() method on free_list to 1434 // remove only the ones that we need to remove. 1435 tear_down_region_sets(true /* free_list_only */); 1436 shrink_helper(shrink_bytes); 1437 rebuild_region_sets(true /* free_list_only */); 1438 1439 _hrm->verify_optional(); 1440 _verifier->verify_region_sets_optional(); 1441 } 1442 1443 class OldRegionSetChecker : public HeapRegionSetChecker { 1444 public: 1445 void check_mt_safety() { 1446 // Master Old Set MT safety protocol: 1447 // (a) If we're at a safepoint, operations on the master old set 1448 // should be invoked: 1449 // - by the VM thread (which will serialize them), or 1450 // - by the GC workers while holding the FreeList_lock, if we're 1451 // at a safepoint for an evacuation pause (this lock is taken 1452 // anyway when an GC alloc region is retired so that a new one 1453 // is allocated from the free list), or 1454 // - by the GC workers while holding the OldSets_lock, if we're at a 1455 // safepoint for a cleanup pause. 1456 // (b) If we're not at a safepoint, operations on the master old set 1457 // should be invoked while holding the Heap_lock. 1458 1459 if (SafepointSynchronize::is_at_safepoint()) { 1460 guarantee(Thread::current()->is_VM_thread() || 1461 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1462 "master old set MT safety protocol at a safepoint"); 1463 } else { 1464 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1465 } 1466 } 1467 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1468 const char* get_description() { return "Old Regions"; } 1469 }; 1470 1471 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1472 public: 1473 void check_mt_safety() { 1474 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1475 "May only change archive regions during initialization or safepoint."); 1476 } 1477 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1478 const char* get_description() { return "Archive Regions"; } 1479 }; 1480 1481 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1482 public: 1483 void check_mt_safety() { 1484 // Humongous Set MT safety protocol: 1485 // (a) If we're at a safepoint, operations on the master humongous 1486 // set should be invoked by either the VM thread (which will 1487 // serialize them) or by the GC workers while holding the 1488 // OldSets_lock. 1489 // (b) If we're not at a safepoint, operations on the master 1490 // humongous set should be invoked while holding the Heap_lock. 1491 1492 if (SafepointSynchronize::is_at_safepoint()) { 1493 guarantee(Thread::current()->is_VM_thread() || 1494 OldSets_lock->owned_by_self(), 1495 "master humongous set MT safety protocol at a safepoint"); 1496 } else { 1497 guarantee(Heap_lock->owned_by_self(), 1498 "master humongous set MT safety protocol outside a safepoint"); 1499 } 1500 } 1501 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1502 const char* get_description() { return "Humongous Regions"; } 1503 }; 1504 1505 G1CollectedHeap::G1CollectedHeap() : 1506 CollectedHeap(), 1507 _young_gen_sampling_thread(NULL), 1508 _workers(NULL), 1509 _card_table(NULL), 1510 _soft_ref_policy(), 1511 _old_set("Old Region Set", new OldRegionSetChecker()), 1512 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1513 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1514 _bot(NULL), 1515 _listener(), 1516 _numa(G1NUMA::create()), 1517 _hrm(NULL), 1518 _allocator(NULL), 1519 _verifier(NULL), 1520 _summary_bytes_used(0), 1521 _archive_allocator(NULL), 1522 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1523 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1524 _expand_heap_after_alloc_failure(true), 1525 _g1mm(NULL), 1526 _humongous_reclaim_candidates(), 1527 _has_humongous_reclaim_candidates(false), 1528 _hr_printer(), 1529 _collector_state(), 1530 _old_marking_cycles_started(0), 1531 _old_marking_cycles_completed(0), 1532 _eden(), 1533 _survivor(), 1534 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1535 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1536 _policy(G1Policy::create_policy(_gc_timer_stw)), 1537 _heap_sizing_policy(NULL), 1538 _collection_set(this, _policy), 1539 _hot_card_cache(NULL), 1540 _rem_set(NULL), 1541 _cm(NULL), 1542 _cm_thread(NULL), 1543 _cr(NULL), 1544 _task_queues(NULL), 1545 _evacuation_failed(false), 1546 _evacuation_failed_info_array(NULL), 1547 _preserved_marks_set(true /* in_c_heap */), 1548 #ifndef PRODUCT 1549 _evacuation_failure_alot_for_current_gc(false), 1550 _evacuation_failure_alot_gc_number(0), 1551 _evacuation_failure_alot_count(0), 1552 #endif 1553 _ref_processor_stw(NULL), 1554 _is_alive_closure_stw(this), 1555 _is_subject_to_discovery_stw(this), 1556 _ref_processor_cm(NULL), 1557 _is_alive_closure_cm(this), 1558 _is_subject_to_discovery_cm(this), 1559 _region_attr() { 1560 1561 _verifier = new G1HeapVerifier(this); 1562 1563 _allocator = new G1Allocator(this); 1564 1565 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1566 1567 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1568 1569 // Override the default _filler_array_max_size so that no humongous filler 1570 // objects are created. 1571 _filler_array_max_size = _humongous_object_threshold_in_words; 1572 1573 uint n_queues = ParallelGCThreads; 1574 _task_queues = new RefToScanQueueSet(n_queues); 1575 1576 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1577 1578 for (uint i = 0; i < n_queues; i++) { 1579 RefToScanQueue* q = new RefToScanQueue(); 1580 q->initialize(); 1581 _task_queues->register_queue(i, q); 1582 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1583 } 1584 1585 // Initialize the G1EvacuationFailureALot counters and flags. 1586 NOT_PRODUCT(reset_evacuation_should_fail();) 1587 _gc_tracer_stw->initialize(); 1588 1589 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1590 } 1591 1592 static size_t actual_reserved_page_size(ReservedSpace rs) { 1593 size_t page_size = os::vm_page_size(); 1594 if (UseLargePages) { 1595 // There are two ways to manage large page memory. 1596 // 1. OS supports committing large page memory. 1597 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1598 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1599 // we reserved memory without large page. 1600 if (os::can_commit_large_page_memory() || rs.special()) { 1601 // An alignment at ReservedSpace comes from preferred page size or 1602 // heap alignment, and if the alignment came from heap alignment, it could be 1603 // larger than large pages size. So need to cap with the large page size. 1604 page_size = MIN2(rs.alignment(), os::large_page_size()); 1605 } 1606 } 1607 1608 return page_size; 1609 } 1610 1611 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1612 size_t size, 1613 size_t translation_factor) { 1614 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1615 // Allocate a new reserved space, preferring to use large pages. 1616 ReservedSpace rs(size, preferred_page_size); 1617 size_t page_size = actual_reserved_page_size(rs); 1618 G1RegionToSpaceMapper* result = 1619 G1RegionToSpaceMapper::create_mapper(rs, 1620 size, 1621 page_size, 1622 HeapRegion::GrainBytes, 1623 translation_factor, 1624 mtGC); 1625 1626 os::trace_page_sizes_for_requested_size(description, 1627 size, 1628 preferred_page_size, 1629 page_size, 1630 rs.base(), 1631 rs.size()); 1632 1633 return result; 1634 } 1635 1636 jint G1CollectedHeap::initialize_concurrent_refinement() { 1637 jint ecode = JNI_OK; 1638 _cr = G1ConcurrentRefine::create(&ecode); 1639 return ecode; 1640 } 1641 1642 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1643 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1644 if (_young_gen_sampling_thread->osthread() == NULL) { 1645 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1646 return JNI_ENOMEM; 1647 } 1648 return JNI_OK; 1649 } 1650 1651 jint G1CollectedHeap::initialize() { 1652 1653 // Necessary to satisfy locking discipline assertions. 1654 1655 MutexLocker x(Heap_lock); 1656 1657 // While there are no constraints in the GC code that HeapWordSize 1658 // be any particular value, there are multiple other areas in the 1659 // system which believe this to be true (e.g. oop->object_size in some 1660 // cases incorrectly returns the size in wordSize units rather than 1661 // HeapWordSize). 1662 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1663 1664 size_t init_byte_size = InitialHeapSize; 1665 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1666 1667 // Ensure that the sizes are properly aligned. 1668 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1669 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1670 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1671 1672 // Reserve the maximum. 1673 1674 // When compressed oops are enabled, the preferred heap base 1675 // is calculated by subtracting the requested size from the 1676 // 32Gb boundary and using the result as the base address for 1677 // heap reservation. If the requested size is not aligned to 1678 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1679 // into the ReservedHeapSpace constructor) then the actual 1680 // base of the reserved heap may end up differing from the 1681 // address that was requested (i.e. the preferred heap base). 1682 // If this happens then we could end up using a non-optimal 1683 // compressed oops mode. 1684 1685 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1686 HeapAlignment); 1687 1688 initialize_reserved_region(heap_rs); 1689 1690 // Create the barrier set for the entire reserved region. 1691 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1692 ct->initialize(); 1693 G1BarrierSet* bs = new G1BarrierSet(ct); 1694 bs->initialize(); 1695 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1696 BarrierSet::set_barrier_set(bs); 1697 _card_table = ct; 1698 1699 { 1700 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1701 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1702 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1703 } 1704 1705 // Create the hot card cache. 1706 _hot_card_cache = new G1HotCardCache(this); 1707 1708 // Carve out the G1 part of the heap. 1709 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1710 size_t page_size = actual_reserved_page_size(heap_rs); 1711 G1RegionToSpaceMapper* heap_storage = 1712 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1713 g1_rs.size(), 1714 page_size, 1715 HeapRegion::GrainBytes, 1716 1, 1717 mtJavaHeap); 1718 if(heap_storage == NULL) { 1719 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1720 return JNI_ERR; 1721 } 1722 1723 os::trace_page_sizes("Heap", 1724 MinHeapSize, 1725 reserved_byte_size, 1726 page_size, 1727 heap_rs.base(), 1728 heap_rs.size()); 1729 heap_storage->set_mapping_changed_listener(&_listener); 1730 1731 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1732 G1RegionToSpaceMapper* bot_storage = 1733 create_aux_memory_mapper("Block Offset Table", 1734 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1735 G1BlockOffsetTable::heap_map_factor()); 1736 1737 G1RegionToSpaceMapper* cardtable_storage = 1738 create_aux_memory_mapper("Card Table", 1739 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1740 G1CardTable::heap_map_factor()); 1741 1742 G1RegionToSpaceMapper* card_counts_storage = 1743 create_aux_memory_mapper("Card Counts Table", 1744 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1745 G1CardCounts::heap_map_factor()); 1746 1747 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1748 G1RegionToSpaceMapper* prev_bitmap_storage = 1749 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1750 G1RegionToSpaceMapper* next_bitmap_storage = 1751 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1752 1753 _hrm = HeapRegionManager::create_manager(this); 1754 1755 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1756 _card_table->initialize(cardtable_storage); 1757 1758 // Do later initialization work for concurrent refinement. 1759 _hot_card_cache->initialize(card_counts_storage); 1760 1761 // 6843694 - ensure that the maximum region index can fit 1762 // in the remembered set structures. 1763 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1764 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1765 1766 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1767 // start within the first card. 1768 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1769 // Also create a G1 rem set. 1770 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1771 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1772 1773 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1774 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1775 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1776 "too many cards per region"); 1777 1778 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1779 1780 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1781 1782 { 1783 HeapWord* start = _hrm->reserved().start(); 1784 HeapWord* end = _hrm->reserved().end(); 1785 size_t granularity = HeapRegion::GrainBytes; 1786 1787 _region_attr.initialize(start, end, granularity); 1788 _humongous_reclaim_candidates.initialize(start, end, granularity); 1789 } 1790 1791 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1792 true /* are_GC_task_threads */, 1793 false /* are_ConcurrentGC_threads */); 1794 if (_workers == NULL) { 1795 return JNI_ENOMEM; 1796 } 1797 _workers->initialize_workers(); 1798 1799 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1800 1801 // Create the G1ConcurrentMark data structure and thread. 1802 // (Must do this late, so that "max_regions" is defined.) 1803 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1804 if (_cm == NULL || !_cm->completed_initialization()) { 1805 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1806 return JNI_ENOMEM; 1807 } 1808 _cm_thread = _cm->cm_thread(); 1809 1810 // Now expand into the initial heap size. 1811 if (!expand(init_byte_size, _workers)) { 1812 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1813 return JNI_ENOMEM; 1814 } 1815 1816 // Perform any initialization actions delegated to the policy. 1817 policy()->init(this, &_collection_set); 1818 1819 jint ecode = initialize_concurrent_refinement(); 1820 if (ecode != JNI_OK) { 1821 return ecode; 1822 } 1823 1824 ecode = initialize_young_gen_sampling_thread(); 1825 if (ecode != JNI_OK) { 1826 return ecode; 1827 } 1828 1829 { 1830 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1831 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1832 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1833 } 1834 1835 // Here we allocate the dummy HeapRegion that is required by the 1836 // G1AllocRegion class. 1837 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1838 1839 // We'll re-use the same region whether the alloc region will 1840 // require BOT updates or not and, if it doesn't, then a non-young 1841 // region will complain that it cannot support allocations without 1842 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1843 dummy_region->set_eden(); 1844 // Make sure it's full. 1845 dummy_region->set_top(dummy_region->end()); 1846 G1AllocRegion::setup(this, dummy_region); 1847 1848 _allocator->init_mutator_alloc_regions(); 1849 1850 // Do create of the monitoring and management support so that 1851 // values in the heap have been properly initialized. 1852 _g1mm = new G1MonitoringSupport(this); 1853 1854 G1StringDedup::initialize(); 1855 1856 _preserved_marks_set.init(ParallelGCThreads); 1857 1858 _collection_set.initialize(max_regions()); 1859 1860 return JNI_OK; 1861 } 1862 1863 void G1CollectedHeap::stop() { 1864 // Stop all concurrent threads. We do this to make sure these threads 1865 // do not continue to execute and access resources (e.g. logging) 1866 // that are destroyed during shutdown. 1867 _cr->stop(); 1868 _young_gen_sampling_thread->stop(); 1869 _cm_thread->stop(); 1870 if (G1StringDedup::is_enabled()) { 1871 G1StringDedup::stop(); 1872 } 1873 } 1874 1875 void G1CollectedHeap::safepoint_synchronize_begin() { 1876 SuspendibleThreadSet::synchronize(); 1877 } 1878 1879 void G1CollectedHeap::safepoint_synchronize_end() { 1880 SuspendibleThreadSet::desynchronize(); 1881 } 1882 1883 void G1CollectedHeap::post_initialize() { 1884 CollectedHeap::post_initialize(); 1885 ref_processing_init(); 1886 } 1887 1888 void G1CollectedHeap::ref_processing_init() { 1889 // Reference processing in G1 currently works as follows: 1890 // 1891 // * There are two reference processor instances. One is 1892 // used to record and process discovered references 1893 // during concurrent marking; the other is used to 1894 // record and process references during STW pauses 1895 // (both full and incremental). 1896 // * Both ref processors need to 'span' the entire heap as 1897 // the regions in the collection set may be dotted around. 1898 // 1899 // * For the concurrent marking ref processor: 1900 // * Reference discovery is enabled at initial marking. 1901 // * Reference discovery is disabled and the discovered 1902 // references processed etc during remarking. 1903 // * Reference discovery is MT (see below). 1904 // * Reference discovery requires a barrier (see below). 1905 // * Reference processing may or may not be MT 1906 // (depending on the value of ParallelRefProcEnabled 1907 // and ParallelGCThreads). 1908 // * A full GC disables reference discovery by the CM 1909 // ref processor and abandons any entries on it's 1910 // discovered lists. 1911 // 1912 // * For the STW processor: 1913 // * Non MT discovery is enabled at the start of a full GC. 1914 // * Processing and enqueueing during a full GC is non-MT. 1915 // * During a full GC, references are processed after marking. 1916 // 1917 // * Discovery (may or may not be MT) is enabled at the start 1918 // of an incremental evacuation pause. 1919 // * References are processed near the end of a STW evacuation pause. 1920 // * For both types of GC: 1921 // * Discovery is atomic - i.e. not concurrent. 1922 // * Reference discovery will not need a barrier. 1923 1924 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1925 1926 // Concurrent Mark ref processor 1927 _ref_processor_cm = 1928 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1929 mt_processing, // mt processing 1930 ParallelGCThreads, // degree of mt processing 1931 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1932 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1933 false, // Reference discovery is not atomic 1934 &_is_alive_closure_cm, // is alive closure 1935 true); // allow changes to number of processing threads 1936 1937 // STW ref processor 1938 _ref_processor_stw = 1939 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1940 mt_processing, // mt processing 1941 ParallelGCThreads, // degree of mt processing 1942 (ParallelGCThreads > 1), // mt discovery 1943 ParallelGCThreads, // degree of mt discovery 1944 true, // Reference discovery is atomic 1945 &_is_alive_closure_stw, // is alive closure 1946 true); // allow changes to number of processing threads 1947 } 1948 1949 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1950 return &_soft_ref_policy; 1951 } 1952 1953 size_t G1CollectedHeap::capacity() const { 1954 return _hrm->length() * HeapRegion::GrainBytes; 1955 } 1956 1957 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1958 return _hrm->total_free_bytes(); 1959 } 1960 1961 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1962 _hot_card_cache->drain(cl, worker_id); 1963 } 1964 1965 // Computes the sum of the storage used by the various regions. 1966 size_t G1CollectedHeap::used() const { 1967 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1968 if (_archive_allocator != NULL) { 1969 result += _archive_allocator->used(); 1970 } 1971 return result; 1972 } 1973 1974 size_t G1CollectedHeap::used_unlocked() const { 1975 return _summary_bytes_used; 1976 } 1977 1978 class SumUsedClosure: public HeapRegionClosure { 1979 size_t _used; 1980 public: 1981 SumUsedClosure() : _used(0) {} 1982 bool do_heap_region(HeapRegion* r) { 1983 _used += r->used(); 1984 return false; 1985 } 1986 size_t result() { return _used; } 1987 }; 1988 1989 size_t G1CollectedHeap::recalculate_used() const { 1990 SumUsedClosure blk; 1991 heap_region_iterate(&blk); 1992 return blk.result(); 1993 } 1994 1995 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1996 switch (cause) { 1997 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1998 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1999 case GCCause::_wb_conc_mark: return true; 2000 default : return false; 2001 } 2002 } 2003 2004 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2005 switch (cause) { 2006 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2007 case GCCause::_g1_humongous_allocation: return true; 2008 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2009 default: return is_user_requested_concurrent_full_gc(cause); 2010 } 2011 } 2012 2013 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2014 if(policy()->force_upgrade_to_full()) { 2015 return true; 2016 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2017 return false; 2018 } else if (has_regions_left_for_allocation()) { 2019 return false; 2020 } else { 2021 return true; 2022 } 2023 } 2024 2025 #ifndef PRODUCT 2026 void G1CollectedHeap::allocate_dummy_regions() { 2027 // Let's fill up most of the region 2028 size_t word_size = HeapRegion::GrainWords - 1024; 2029 // And as a result the region we'll allocate will be humongous. 2030 guarantee(is_humongous(word_size), "sanity"); 2031 2032 // _filler_array_max_size is set to humongous object threshold 2033 // but temporarily change it to use CollectedHeap::fill_with_object(). 2034 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2035 2036 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2037 // Let's use the existing mechanism for the allocation 2038 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2039 if (dummy_obj != NULL) { 2040 MemRegion mr(dummy_obj, word_size); 2041 CollectedHeap::fill_with_object(mr); 2042 } else { 2043 // If we can't allocate once, we probably cannot allocate 2044 // again. Let's get out of the loop. 2045 break; 2046 } 2047 } 2048 } 2049 #endif // !PRODUCT 2050 2051 void G1CollectedHeap::increment_old_marking_cycles_started() { 2052 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2053 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2054 "Wrong marking cycle count (started: %d, completed: %d)", 2055 _old_marking_cycles_started, _old_marking_cycles_completed); 2056 2057 _old_marking_cycles_started++; 2058 } 2059 2060 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2061 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2062 2063 // We assume that if concurrent == true, then the caller is a 2064 // concurrent thread that was joined the Suspendible Thread 2065 // Set. If there's ever a cheap way to check this, we should add an 2066 // assert here. 2067 2068 // Given that this method is called at the end of a Full GC or of a 2069 // concurrent cycle, and those can be nested (i.e., a Full GC can 2070 // interrupt a concurrent cycle), the number of full collections 2071 // completed should be either one (in the case where there was no 2072 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2073 // behind the number of full collections started. 2074 2075 // This is the case for the inner caller, i.e. a Full GC. 2076 assert(concurrent || 2077 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2078 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2079 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2080 "is inconsistent with _old_marking_cycles_completed = %u", 2081 _old_marking_cycles_started, _old_marking_cycles_completed); 2082 2083 // This is the case for the outer caller, i.e. the concurrent cycle. 2084 assert(!concurrent || 2085 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2086 "for outer caller (concurrent cycle): " 2087 "_old_marking_cycles_started = %u " 2088 "is inconsistent with _old_marking_cycles_completed = %u", 2089 _old_marking_cycles_started, _old_marking_cycles_completed); 2090 2091 _old_marking_cycles_completed += 1; 2092 2093 // We need to clear the "in_progress" flag in the CM thread before 2094 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2095 // is set) so that if a waiter requests another System.gc() it doesn't 2096 // incorrectly see that a marking cycle is still in progress. 2097 if (concurrent) { 2098 _cm_thread->set_idle(); 2099 } 2100 2101 // This notify_all() will ensure that a thread that called 2102 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2103 // and it's waiting for a full GC to finish will be woken up. It is 2104 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2105 FullGCCount_lock->notify_all(); 2106 } 2107 2108 void G1CollectedHeap::collect(GCCause::Cause cause) { 2109 try_collect(cause, true); 2110 } 2111 2112 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2113 assert_heap_not_locked(); 2114 2115 bool gc_succeeded; 2116 bool should_retry_gc; 2117 2118 do { 2119 should_retry_gc = false; 2120 2121 uint gc_count_before; 2122 uint old_marking_count_before; 2123 uint full_gc_count_before; 2124 2125 { 2126 MutexLocker ml(Heap_lock); 2127 2128 // Read the GC count while holding the Heap_lock 2129 gc_count_before = total_collections(); 2130 full_gc_count_before = total_full_collections(); 2131 old_marking_count_before = _old_marking_cycles_started; 2132 } 2133 2134 if (should_do_concurrent_full_gc(cause)) { 2135 // Schedule an initial-mark evacuation pause that will start a 2136 // concurrent cycle. We're setting word_size to 0 which means that 2137 // we are not requesting a post-GC allocation. 2138 VM_G1CollectForAllocation op(0, /* word_size */ 2139 gc_count_before, 2140 cause, 2141 true, /* should_initiate_conc_mark */ 2142 policy()->max_pause_time_ms()); 2143 VMThread::execute(&op); 2144 gc_succeeded = op.gc_succeeded(); 2145 if (!gc_succeeded && retry_on_gc_failure) { 2146 if (old_marking_count_before == _old_marking_cycles_started) { 2147 should_retry_gc = op.should_retry_gc(); 2148 } else { 2149 // A Full GC happened while we were trying to schedule the 2150 // concurrent cycle. No point in starting a new cycle given 2151 // that the whole heap was collected anyway. 2152 } 2153 2154 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2155 GCLocker::stall_until_clear(); 2156 } 2157 } 2158 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2159 // Return false to be consistent with VMOp failure due to 2160 // another collection slipping in after our gc_count but before 2161 // our request is processed. _gc_locker collections upgraded by 2162 // GCLockerInvokesConcurrent are handled above and never discarded. 2163 return false; 2164 } else { 2165 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2166 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2167 2168 // Schedule a standard evacuation pause. We're setting word_size 2169 // to 0 which means that we are not requesting a post-GC allocation. 2170 VM_G1CollectForAllocation op(0, /* word_size */ 2171 gc_count_before, 2172 cause, 2173 false, /* should_initiate_conc_mark */ 2174 policy()->max_pause_time_ms()); 2175 VMThread::execute(&op); 2176 gc_succeeded = op.gc_succeeded(); 2177 } else { 2178 // Schedule a Full GC. 2179 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2180 VMThread::execute(&op); 2181 gc_succeeded = op.gc_succeeded(); 2182 } 2183 } 2184 } while (should_retry_gc); 2185 return gc_succeeded; 2186 } 2187 2188 bool G1CollectedHeap::is_in(const void* p) const { 2189 if (_hrm->reserved().contains(p)) { 2190 // Given that we know that p is in the reserved space, 2191 // heap_region_containing() should successfully 2192 // return the containing region. 2193 HeapRegion* hr = heap_region_containing(p); 2194 return hr->is_in(p); 2195 } else { 2196 return false; 2197 } 2198 } 2199 2200 #ifdef ASSERT 2201 bool G1CollectedHeap::is_in_exact(const void* p) const { 2202 bool contains = reserved_region().contains(p); 2203 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2204 if (contains && available) { 2205 return true; 2206 } else { 2207 return false; 2208 } 2209 } 2210 #endif 2211 2212 // Iteration functions. 2213 2214 // Iterates an ObjectClosure over all objects within a HeapRegion. 2215 2216 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2217 ObjectClosure* _cl; 2218 public: 2219 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2220 bool do_heap_region(HeapRegion* r) { 2221 if (!r->is_continues_humongous()) { 2222 r->object_iterate(_cl); 2223 } 2224 return false; 2225 } 2226 }; 2227 2228 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2229 IterateObjectClosureRegionClosure blk(cl); 2230 heap_region_iterate(&blk); 2231 } 2232 2233 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2234 _hrm->iterate(cl); 2235 } 2236 2237 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2238 HeapRegionClaimer *hrclaimer, 2239 uint worker_id) const { 2240 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2241 } 2242 2243 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2244 HeapRegionClaimer *hrclaimer) const { 2245 _hrm->par_iterate(cl, hrclaimer, 0); 2246 } 2247 2248 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2249 _collection_set.iterate(cl); 2250 } 2251 2252 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2253 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2254 } 2255 2256 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2257 HeapRegion* hr = heap_region_containing(addr); 2258 return hr->block_start(addr); 2259 } 2260 2261 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2262 HeapRegion* hr = heap_region_containing(addr); 2263 return hr->block_is_obj(addr); 2264 } 2265 2266 bool G1CollectedHeap::supports_tlab_allocation() const { 2267 return true; 2268 } 2269 2270 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2271 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2272 } 2273 2274 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2275 return _eden.length() * HeapRegion::GrainBytes; 2276 } 2277 2278 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2279 // must be equal to the humongous object limit. 2280 size_t G1CollectedHeap::max_tlab_size() const { 2281 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2282 } 2283 2284 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2285 return _allocator->unsafe_max_tlab_alloc(); 2286 } 2287 2288 size_t G1CollectedHeap::max_capacity() const { 2289 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2290 } 2291 2292 size_t G1CollectedHeap::max_reserved_capacity() const { 2293 return _hrm->max_length() * HeapRegion::GrainBytes; 2294 } 2295 2296 jlong G1CollectedHeap::millis_since_last_gc() { 2297 // See the notes in GenCollectedHeap::millis_since_last_gc() 2298 // for more information about the implementation. 2299 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2300 _policy->collection_pause_end_millis(); 2301 if (ret_val < 0) { 2302 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2303 ". returning zero instead.", ret_val); 2304 return 0; 2305 } 2306 return ret_val; 2307 } 2308 2309 void G1CollectedHeap::deduplicate_string(oop str) { 2310 assert(java_lang_String::is_instance(str), "invariant"); 2311 2312 if (G1StringDedup::is_enabled()) { 2313 G1StringDedup::deduplicate(str); 2314 } 2315 } 2316 2317 void G1CollectedHeap::prepare_for_verify() { 2318 _verifier->prepare_for_verify(); 2319 } 2320 2321 void G1CollectedHeap::verify(VerifyOption vo) { 2322 _verifier->verify(vo); 2323 } 2324 2325 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2326 return true; 2327 } 2328 2329 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2330 return _cm_thread->request_concurrent_phase(phase); 2331 } 2332 2333 bool G1CollectedHeap::is_heterogeneous_heap() const { 2334 return G1Arguments::is_heterogeneous_heap(); 2335 } 2336 2337 class PrintRegionClosure: public HeapRegionClosure { 2338 outputStream* _st; 2339 public: 2340 PrintRegionClosure(outputStream* st) : _st(st) {} 2341 bool do_heap_region(HeapRegion* r) { 2342 r->print_on(_st); 2343 return false; 2344 } 2345 }; 2346 2347 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2348 const HeapRegion* hr, 2349 const VerifyOption vo) const { 2350 switch (vo) { 2351 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2352 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2353 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2354 default: ShouldNotReachHere(); 2355 } 2356 return false; // keep some compilers happy 2357 } 2358 2359 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2360 const VerifyOption vo) const { 2361 switch (vo) { 2362 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2363 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2364 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2365 default: ShouldNotReachHere(); 2366 } 2367 return false; // keep some compilers happy 2368 } 2369 2370 void G1CollectedHeap::print_heap_regions() const { 2371 LogTarget(Trace, gc, heap, region) lt; 2372 if (lt.is_enabled()) { 2373 LogStream ls(lt); 2374 print_regions_on(&ls); 2375 } 2376 } 2377 2378 void G1CollectedHeap::print_on(outputStream* st) const { 2379 st->print(" %-20s", "garbage-first heap"); 2380 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2381 capacity()/K, used_unlocked()/K); 2382 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2383 p2i(_hrm->reserved().start()), 2384 p2i(_hrm->reserved().end())); 2385 st->cr(); 2386 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2387 uint young_regions = young_regions_count(); 2388 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2389 (size_t) young_regions * HeapRegion::GrainBytes / K); 2390 uint survivor_regions = survivor_regions_count(); 2391 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2392 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2393 st->cr(); 2394 if (_numa->is_enabled()) { 2395 uint num_nodes = _numa->num_active_nodes(); 2396 st->print(" remaining free region(s) on each NUMA node: "); 2397 const int* node_ids = _numa->node_ids(); 2398 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2399 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index)); 2400 } 2401 st->cr(); 2402 } 2403 MetaspaceUtils::print_on(st); 2404 } 2405 2406 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2407 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2408 "HS=humongous(starts), HC=humongous(continues), " 2409 "CS=collection set, F=free, " 2410 "OA=open archive, CA=closed archive, " 2411 "TAMS=top-at-mark-start (previous, next)"); 2412 PrintRegionClosure blk(st); 2413 heap_region_iterate(&blk); 2414 } 2415 2416 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2417 print_on(st); 2418 2419 // Print the per-region information. 2420 print_regions_on(st); 2421 } 2422 2423 void G1CollectedHeap::print_on_error(outputStream* st) const { 2424 this->CollectedHeap::print_on_error(st); 2425 2426 if (_cm != NULL) { 2427 st->cr(); 2428 _cm->print_on_error(st); 2429 } 2430 } 2431 2432 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2433 workers()->print_worker_threads_on(st); 2434 _cm_thread->print_on(st); 2435 st->cr(); 2436 _cm->print_worker_threads_on(st); 2437 _cr->print_threads_on(st); 2438 _young_gen_sampling_thread->print_on(st); 2439 if (G1StringDedup::is_enabled()) { 2440 G1StringDedup::print_worker_threads_on(st); 2441 } 2442 } 2443 2444 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2445 workers()->threads_do(tc); 2446 tc->do_thread(_cm_thread); 2447 _cm->threads_do(tc); 2448 _cr->threads_do(tc); 2449 tc->do_thread(_young_gen_sampling_thread); 2450 if (G1StringDedup::is_enabled()) { 2451 G1StringDedup::threads_do(tc); 2452 } 2453 } 2454 2455 void G1CollectedHeap::print_tracing_info() const { 2456 rem_set()->print_summary_info(); 2457 concurrent_mark()->print_summary_info(); 2458 } 2459 2460 #ifndef PRODUCT 2461 // Helpful for debugging RSet issues. 2462 2463 class PrintRSetsClosure : public HeapRegionClosure { 2464 private: 2465 const char* _msg; 2466 size_t _occupied_sum; 2467 2468 public: 2469 bool do_heap_region(HeapRegion* r) { 2470 HeapRegionRemSet* hrrs = r->rem_set(); 2471 size_t occupied = hrrs->occupied(); 2472 _occupied_sum += occupied; 2473 2474 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2475 if (occupied == 0) { 2476 tty->print_cr(" RSet is empty"); 2477 } else { 2478 hrrs->print(); 2479 } 2480 tty->print_cr("----------"); 2481 return false; 2482 } 2483 2484 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2485 tty->cr(); 2486 tty->print_cr("========================================"); 2487 tty->print_cr("%s", msg); 2488 tty->cr(); 2489 } 2490 2491 ~PrintRSetsClosure() { 2492 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2493 tty->print_cr("========================================"); 2494 tty->cr(); 2495 } 2496 }; 2497 2498 void G1CollectedHeap::print_cset_rsets() { 2499 PrintRSetsClosure cl("Printing CSet RSets"); 2500 collection_set_iterate_all(&cl); 2501 } 2502 2503 void G1CollectedHeap::print_all_rsets() { 2504 PrintRSetsClosure cl("Printing All RSets");; 2505 heap_region_iterate(&cl); 2506 } 2507 #endif // PRODUCT 2508 2509 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2510 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2511 } 2512 2513 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2514 2515 size_t eden_used_bytes = _eden.used_bytes(); 2516 size_t survivor_used_bytes = _survivor.used_bytes(); 2517 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2518 2519 size_t eden_capacity_bytes = 2520 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2521 2522 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2523 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2524 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2525 } 2526 2527 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2528 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2529 stats->unused(), stats->used(), stats->region_end_waste(), 2530 stats->regions_filled(), stats->direct_allocated(), 2531 stats->failure_used(), stats->failure_waste()); 2532 } 2533 2534 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2535 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2536 gc_tracer->report_gc_heap_summary(when, heap_summary); 2537 2538 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2539 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2540 } 2541 2542 G1CollectedHeap* G1CollectedHeap::heap() { 2543 CollectedHeap* heap = Universe::heap(); 2544 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2545 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2546 return (G1CollectedHeap*)heap; 2547 } 2548 2549 void G1CollectedHeap::gc_prologue(bool full) { 2550 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2551 2552 // This summary needs to be printed before incrementing total collections. 2553 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2554 2555 // Update common counters. 2556 increment_total_collections(full /* full gc */); 2557 if (full || collector_state()->in_initial_mark_gc()) { 2558 increment_old_marking_cycles_started(); 2559 } 2560 2561 // Fill TLAB's and such 2562 double start = os::elapsedTime(); 2563 ensure_parsability(true); 2564 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2565 } 2566 2567 void G1CollectedHeap::gc_epilogue(bool full) { 2568 // Update common counters. 2569 if (full) { 2570 // Update the number of full collections that have been completed. 2571 increment_old_marking_cycles_completed(false /* concurrent */); 2572 } 2573 2574 // We are at the end of the GC. Total collections has already been increased. 2575 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2576 2577 // FIXME: what is this about? 2578 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2579 // is set. 2580 #if COMPILER2_OR_JVMCI 2581 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2582 #endif 2583 2584 double start = os::elapsedTime(); 2585 resize_all_tlabs(); 2586 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2587 2588 MemoryService::track_memory_usage(); 2589 // We have just completed a GC. Update the soft reference 2590 // policy with the new heap occupancy 2591 Universe::update_heap_info_at_gc(); 2592 2593 // Print NUMA statistics. 2594 _numa->print_statistics(); 2595 } 2596 2597 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2598 LogTarget(Trace, gc, heap, verify) lt; 2599 2600 if (lt.is_enabled()) { 2601 LogStream ls(lt); 2602 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2603 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2604 heap_region_iterate(&cl); 2605 } 2606 } 2607 2608 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2609 uint gc_count_before, 2610 bool* succeeded, 2611 GCCause::Cause gc_cause) { 2612 assert_heap_not_locked_and_not_at_safepoint(); 2613 VM_G1CollectForAllocation op(word_size, 2614 gc_count_before, 2615 gc_cause, 2616 false, /* should_initiate_conc_mark */ 2617 policy()->max_pause_time_ms()); 2618 VMThread::execute(&op); 2619 2620 HeapWord* result = op.result(); 2621 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2622 assert(result == NULL || ret_succeeded, 2623 "the result should be NULL if the VM did not succeed"); 2624 *succeeded = ret_succeeded; 2625 2626 assert_heap_not_locked(); 2627 return result; 2628 } 2629 2630 void G1CollectedHeap::do_concurrent_mark() { 2631 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2632 if (!_cm_thread->in_progress()) { 2633 _cm_thread->set_started(); 2634 CGC_lock->notify(); 2635 } 2636 } 2637 2638 size_t G1CollectedHeap::pending_card_num() { 2639 struct CountCardsClosure : public ThreadClosure { 2640 size_t _cards; 2641 CountCardsClosure() : _cards(0) {} 2642 virtual void do_thread(Thread* t) { 2643 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2644 } 2645 } count_from_threads; 2646 Threads::threads_do(&count_from_threads); 2647 2648 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2649 dcqs.verify_num_cards(); 2650 2651 return dcqs.num_cards() + count_from_threads._cards; 2652 } 2653 2654 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2655 // We don't nominate objects with many remembered set entries, on 2656 // the assumption that such objects are likely still live. 2657 HeapRegionRemSet* rem_set = r->rem_set(); 2658 2659 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2660 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2661 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2662 } 2663 2664 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2665 private: 2666 size_t _total_humongous; 2667 size_t _candidate_humongous; 2668 2669 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2670 assert(region->is_starts_humongous(), "Must start a humongous object"); 2671 2672 oop obj = oop(region->bottom()); 2673 2674 // Dead objects cannot be eager reclaim candidates. Due to class 2675 // unloading it is unsafe to query their classes so we return early. 2676 if (g1h->is_obj_dead(obj, region)) { 2677 return false; 2678 } 2679 2680 // If we do not have a complete remembered set for the region, then we can 2681 // not be sure that we have all references to it. 2682 if (!region->rem_set()->is_complete()) { 2683 return false; 2684 } 2685 // Candidate selection must satisfy the following constraints 2686 // while concurrent marking is in progress: 2687 // 2688 // * In order to maintain SATB invariants, an object must not be 2689 // reclaimed if it was allocated before the start of marking and 2690 // has not had its references scanned. Such an object must have 2691 // its references (including type metadata) scanned to ensure no 2692 // live objects are missed by the marking process. Objects 2693 // allocated after the start of concurrent marking don't need to 2694 // be scanned. 2695 // 2696 // * An object must not be reclaimed if it is on the concurrent 2697 // mark stack. Objects allocated after the start of concurrent 2698 // marking are never pushed on the mark stack. 2699 // 2700 // Nominating only objects allocated after the start of concurrent 2701 // marking is sufficient to meet both constraints. This may miss 2702 // some objects that satisfy the constraints, but the marking data 2703 // structures don't support efficiently performing the needed 2704 // additional tests or scrubbing of the mark stack. 2705 // 2706 // However, we presently only nominate is_typeArray() objects. 2707 // A humongous object containing references induces remembered 2708 // set entries on other regions. In order to reclaim such an 2709 // object, those remembered sets would need to be cleaned up. 2710 // 2711 // We also treat is_typeArray() objects specially, allowing them 2712 // to be reclaimed even if allocated before the start of 2713 // concurrent mark. For this we rely on mark stack insertion to 2714 // exclude is_typeArray() objects, preventing reclaiming an object 2715 // that is in the mark stack. We also rely on the metadata for 2716 // such objects to be built-in and so ensured to be kept live. 2717 // Frequent allocation and drop of large binary blobs is an 2718 // important use case for eager reclaim, and this special handling 2719 // may reduce needed headroom. 2720 2721 return obj->is_typeArray() && 2722 g1h->is_potential_eager_reclaim_candidate(region); 2723 } 2724 2725 public: 2726 RegisterRegionsWithRegionAttrTableClosure() 2727 : _total_humongous(0), 2728 _candidate_humongous(0) { 2729 } 2730 2731 virtual bool do_heap_region(HeapRegion* r) { 2732 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2733 2734 if (!r->is_starts_humongous()) { 2735 g1h->register_region_with_region_attr(r); 2736 return false; 2737 } 2738 2739 bool is_candidate = humongous_region_is_candidate(g1h, r); 2740 uint rindex = r->hrm_index(); 2741 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2742 if (is_candidate) { 2743 g1h->register_humongous_region_with_region_attr(rindex); 2744 _candidate_humongous++; 2745 // We will later handle the remembered sets of these regions. 2746 } else { 2747 g1h->register_region_with_region_attr(r); 2748 } 2749 _total_humongous++; 2750 2751 return false; 2752 } 2753 2754 size_t total_humongous() const { return _total_humongous; } 2755 size_t candidate_humongous() const { return _candidate_humongous; } 2756 }; 2757 2758 void G1CollectedHeap::register_regions_with_region_attr() { 2759 Ticks start = Ticks::now(); 2760 2761 RegisterRegionsWithRegionAttrTableClosure cl; 2762 heap_region_iterate(&cl); 2763 2764 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2765 cl.total_humongous(), 2766 cl.candidate_humongous()); 2767 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2768 } 2769 2770 #ifndef PRODUCT 2771 void G1CollectedHeap::verify_region_attr_remset_update() { 2772 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2773 public: 2774 virtual bool do_heap_region(HeapRegion* r) { 2775 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2776 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2777 assert(r->rem_set()->is_tracked() == needs_remset_update, 2778 "Region %u remset tracking status (%s) different to region attribute (%s)", 2779 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2780 return false; 2781 } 2782 } cl; 2783 heap_region_iterate(&cl); 2784 } 2785 #endif 2786 2787 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2788 public: 2789 bool do_heap_region(HeapRegion* hr) { 2790 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2791 hr->verify_rem_set(); 2792 } 2793 return false; 2794 } 2795 }; 2796 2797 uint G1CollectedHeap::num_task_queues() const { 2798 return _task_queues->size(); 2799 } 2800 2801 #if TASKQUEUE_STATS 2802 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2803 st->print_raw_cr("GC Task Stats"); 2804 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2805 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2806 } 2807 2808 void G1CollectedHeap::print_taskqueue_stats() const { 2809 if (!log_is_enabled(Trace, gc, task, stats)) { 2810 return; 2811 } 2812 Log(gc, task, stats) log; 2813 ResourceMark rm; 2814 LogStream ls(log.trace()); 2815 outputStream* st = &ls; 2816 2817 print_taskqueue_stats_hdr(st); 2818 2819 TaskQueueStats totals; 2820 const uint n = num_task_queues(); 2821 for (uint i = 0; i < n; ++i) { 2822 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2823 totals += task_queue(i)->stats; 2824 } 2825 st->print_raw("tot "); totals.print(st); st->cr(); 2826 2827 DEBUG_ONLY(totals.verify()); 2828 } 2829 2830 void G1CollectedHeap::reset_taskqueue_stats() { 2831 const uint n = num_task_queues(); 2832 for (uint i = 0; i < n; ++i) { 2833 task_queue(i)->stats.reset(); 2834 } 2835 } 2836 #endif // TASKQUEUE_STATS 2837 2838 void G1CollectedHeap::wait_for_root_region_scanning() { 2839 double scan_wait_start = os::elapsedTime(); 2840 // We have to wait until the CM threads finish scanning the 2841 // root regions as it's the only way to ensure that all the 2842 // objects on them have been correctly scanned before we start 2843 // moving them during the GC. 2844 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2845 double wait_time_ms = 0.0; 2846 if (waited) { 2847 double scan_wait_end = os::elapsedTime(); 2848 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2849 } 2850 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2851 } 2852 2853 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2854 private: 2855 G1HRPrinter* _hr_printer; 2856 public: 2857 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2858 2859 virtual bool do_heap_region(HeapRegion* r) { 2860 _hr_printer->cset(r); 2861 return false; 2862 } 2863 }; 2864 2865 void G1CollectedHeap::start_new_collection_set() { 2866 double start = os::elapsedTime(); 2867 2868 collection_set()->start_incremental_building(); 2869 2870 clear_region_attr(); 2871 2872 guarantee(_eden.length() == 0, "eden should have been cleared"); 2873 policy()->transfer_survivors_to_cset(survivor()); 2874 2875 // We redo the verification but now wrt to the new CSet which 2876 // has just got initialized after the previous CSet was freed. 2877 _cm->verify_no_collection_set_oops(); 2878 2879 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2880 } 2881 2882 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2883 2884 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2885 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2886 collection_set()->optional_region_length()); 2887 2888 _cm->verify_no_collection_set_oops(); 2889 2890 if (_hr_printer.is_active()) { 2891 G1PrintCollectionSetClosure cl(&_hr_printer); 2892 _collection_set.iterate(&cl); 2893 _collection_set.iterate_optional(&cl); 2894 } 2895 } 2896 2897 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2898 if (collector_state()->in_initial_mark_gc()) { 2899 return G1HeapVerifier::G1VerifyConcurrentStart; 2900 } else if (collector_state()->in_young_only_phase()) { 2901 return G1HeapVerifier::G1VerifyYoungNormal; 2902 } else { 2903 return G1HeapVerifier::G1VerifyMixed; 2904 } 2905 } 2906 2907 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2908 if (VerifyRememberedSets) { 2909 log_info(gc, verify)("[Verifying RemSets before GC]"); 2910 VerifyRegionRemSetClosure v_cl; 2911 heap_region_iterate(&v_cl); 2912 } 2913 _verifier->verify_before_gc(type); 2914 _verifier->check_bitmaps("GC Start"); 2915 verify_numa_regions("GC Start"); 2916 } 2917 2918 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2919 if (VerifyRememberedSets) { 2920 log_info(gc, verify)("[Verifying RemSets after GC]"); 2921 VerifyRegionRemSetClosure v_cl; 2922 heap_region_iterate(&v_cl); 2923 } 2924 _verifier->verify_after_gc(type); 2925 _verifier->check_bitmaps("GC End"); 2926 verify_numa_regions("GC End"); 2927 } 2928 2929 void G1CollectedHeap::expand_heap_after_young_collection(){ 2930 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2931 if (expand_bytes > 0) { 2932 // No need for an ergo logging here, 2933 // expansion_amount() does this when it returns a value > 0. 2934 double expand_ms; 2935 if (!expand(expand_bytes, _workers, &expand_ms)) { 2936 // We failed to expand the heap. Cannot do anything about it. 2937 } 2938 phase_times()->record_expand_heap_time(expand_ms); 2939 } 2940 } 2941 2942 const char* G1CollectedHeap::young_gc_name() const { 2943 if (collector_state()->in_initial_mark_gc()) { 2944 return "Pause Young (Concurrent Start)"; 2945 } else if (collector_state()->in_young_only_phase()) { 2946 if (collector_state()->in_young_gc_before_mixed()) { 2947 return "Pause Young (Prepare Mixed)"; 2948 } else { 2949 return "Pause Young (Normal)"; 2950 } 2951 } else { 2952 return "Pause Young (Mixed)"; 2953 } 2954 } 2955 2956 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2957 assert_at_safepoint_on_vm_thread(); 2958 guarantee(!is_gc_active(), "collection is not reentrant"); 2959 2960 if (GCLocker::check_active_before_gc()) { 2961 return false; 2962 } 2963 2964 GCIdMark gc_id_mark; 2965 2966 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2967 ResourceMark rm; 2968 2969 policy()->note_gc_start(); 2970 2971 _gc_timer_stw->register_gc_start(); 2972 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2973 2974 wait_for_root_region_scanning(); 2975 2976 print_heap_before_gc(); 2977 print_heap_regions(); 2978 trace_heap_before_gc(_gc_tracer_stw); 2979 2980 _verifier->verify_region_sets_optional(); 2981 _verifier->verify_dirty_young_regions(); 2982 2983 // We should not be doing initial mark unless the conc mark thread is running 2984 if (!_cm_thread->should_terminate()) { 2985 // This call will decide whether this pause is an initial-mark 2986 // pause. If it is, in_initial_mark_gc() will return true 2987 // for the duration of this pause. 2988 policy()->decide_on_conc_mark_initiation(); 2989 } 2990 2991 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2992 assert(!collector_state()->in_initial_mark_gc() || 2993 collector_state()->in_young_only_phase(), "sanity"); 2994 // We also do not allow mixed GCs during marking. 2995 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2996 2997 // Record whether this pause is an initial mark. When the current 2998 // thread has completed its logging output and it's safe to signal 2999 // the CM thread, the flag's value in the policy has been reset. 3000 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 3001 if (should_start_conc_mark) { 3002 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3003 } 3004 3005 // Inner scope for scope based logging, timers, and stats collection 3006 { 3007 G1EvacuationInfo evacuation_info; 3008 3009 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3010 3011 GCTraceCPUTime tcpu; 3012 3013 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3014 3015 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3016 workers()->active_workers(), 3017 Threads::number_of_non_daemon_threads()); 3018 active_workers = workers()->update_active_workers(active_workers); 3019 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3020 3021 G1MonitoringScope ms(g1mm(), 3022 false /* full_gc */, 3023 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3024 3025 G1HeapTransition heap_transition(this); 3026 size_t heap_used_bytes_before_gc = used(); 3027 3028 { 3029 IsGCActiveMark x; 3030 3031 gc_prologue(false); 3032 3033 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3034 verify_before_young_collection(verify_type); 3035 3036 { 3037 // The elapsed time induced by the start time below deliberately elides 3038 // the possible verification above. 3039 double sample_start_time_sec = os::elapsedTime(); 3040 3041 // Please see comment in g1CollectedHeap.hpp and 3042 // G1CollectedHeap::ref_processing_init() to see how 3043 // reference processing currently works in G1. 3044 _ref_processor_stw->enable_discovery(); 3045 3046 // We want to temporarily turn off discovery by the 3047 // CM ref processor, if necessary, and turn it back on 3048 // on again later if we do. Using a scoped 3049 // NoRefDiscovery object will do this. 3050 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3051 3052 policy()->record_collection_pause_start(sample_start_time_sec); 3053 3054 // Forget the current allocation region (we might even choose it to be part 3055 // of the collection set!). 3056 _allocator->release_mutator_alloc_regions(); 3057 3058 calculate_collection_set(evacuation_info, target_pause_time_ms); 3059 3060 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3061 G1ParScanThreadStateSet per_thread_states(this, 3062 &rdcqs, 3063 workers()->active_workers(), 3064 collection_set()->young_region_length(), 3065 collection_set()->optional_region_length()); 3066 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3067 3068 // Actually do the work... 3069 evacuate_initial_collection_set(&per_thread_states); 3070 3071 if (_collection_set.optional_region_length() != 0) { 3072 evacuate_optional_collection_set(&per_thread_states); 3073 } 3074 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3075 3076 start_new_collection_set(); 3077 3078 _survivor_evac_stats.adjust_desired_plab_sz(); 3079 _old_evac_stats.adjust_desired_plab_sz(); 3080 3081 if (should_start_conc_mark) { 3082 // We have to do this before we notify the CM threads that 3083 // they can start working to make sure that all the 3084 // appropriate initialization is done on the CM object. 3085 concurrent_mark()->post_initial_mark(); 3086 // Note that we don't actually trigger the CM thread at 3087 // this point. We do that later when we're sure that 3088 // the current thread has completed its logging output. 3089 } 3090 3091 allocate_dummy_regions(); 3092 3093 _allocator->init_mutator_alloc_regions(); 3094 3095 expand_heap_after_young_collection(); 3096 3097 double sample_end_time_sec = os::elapsedTime(); 3098 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3099 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc); 3100 } 3101 3102 verify_after_young_collection(verify_type); 3103 3104 #ifdef TRACESPINNING 3105 ParallelTaskTerminator::print_termination_counts(); 3106 #endif 3107 3108 gc_epilogue(false); 3109 } 3110 3111 // Print the remainder of the GC log output. 3112 if (evacuation_failed()) { 3113 log_info(gc)("To-space exhausted"); 3114 } 3115 3116 policy()->print_phases(); 3117 heap_transition.print(); 3118 3119 _hrm->verify_optional(); 3120 _verifier->verify_region_sets_optional(); 3121 3122 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3123 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3124 3125 print_heap_after_gc(); 3126 print_heap_regions(); 3127 trace_heap_after_gc(_gc_tracer_stw); 3128 3129 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3130 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3131 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3132 // before any GC notifications are raised. 3133 g1mm()->update_sizes(); 3134 3135 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3136 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3137 _gc_timer_stw->register_gc_end(); 3138 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3139 } 3140 // It should now be safe to tell the concurrent mark thread to start 3141 // without its logging output interfering with the logging output 3142 // that came from the pause. 3143 3144 if (should_start_conc_mark) { 3145 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3146 // thread(s) could be running concurrently with us. Make sure that anything 3147 // after this point does not assume that we are the only GC thread running. 3148 // Note: of course, the actual marking work will not start until the safepoint 3149 // itself is released in SuspendibleThreadSet::desynchronize(). 3150 do_concurrent_mark(); 3151 } 3152 3153 return true; 3154 } 3155 3156 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3157 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3158 workers()->run_task(&rsfp_task); 3159 } 3160 3161 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3162 double remove_self_forwards_start = os::elapsedTime(); 3163 3164 remove_self_forwarding_pointers(rdcqs); 3165 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3166 _preserved_marks_set.restore(&task_executor); 3167 3168 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3169 } 3170 3171 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3172 if (!_evacuation_failed) { 3173 _evacuation_failed = true; 3174 } 3175 3176 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3177 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3178 } 3179 3180 bool G1ParEvacuateFollowersClosure::offer_termination() { 3181 EventGCPhaseParallel event; 3182 G1ParScanThreadState* const pss = par_scan_state(); 3183 start_term_time(); 3184 const bool res = terminator()->offer_termination(); 3185 end_term_time(); 3186 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3187 return res; 3188 } 3189 3190 void G1ParEvacuateFollowersClosure::do_void() { 3191 EventGCPhaseParallel event; 3192 G1ParScanThreadState* const pss = par_scan_state(); 3193 pss->trim_queue(); 3194 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3195 do { 3196 EventGCPhaseParallel event; 3197 pss->steal_and_trim_queue(queues()); 3198 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3199 } while (!offer_termination()); 3200 } 3201 3202 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3203 bool class_unloading_occurred) { 3204 uint num_workers = workers()->active_workers(); 3205 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3206 workers()->run_task(&unlink_task); 3207 } 3208 3209 // Clean string dedup data structures. 3210 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3211 // record the durations of the phases. Hence the almost-copy. 3212 class G1StringDedupCleaningTask : public AbstractGangTask { 3213 BoolObjectClosure* _is_alive; 3214 OopClosure* _keep_alive; 3215 G1GCPhaseTimes* _phase_times; 3216 3217 public: 3218 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3219 OopClosure* keep_alive, 3220 G1GCPhaseTimes* phase_times) : 3221 AbstractGangTask("Partial Cleaning Task"), 3222 _is_alive(is_alive), 3223 _keep_alive(keep_alive), 3224 _phase_times(phase_times) 3225 { 3226 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3227 StringDedup::gc_prologue(true); 3228 } 3229 3230 ~G1StringDedupCleaningTask() { 3231 StringDedup::gc_epilogue(); 3232 } 3233 3234 void work(uint worker_id) { 3235 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3236 { 3237 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3238 StringDedupQueue::unlink_or_oops_do(&cl); 3239 } 3240 { 3241 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3242 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3243 } 3244 } 3245 }; 3246 3247 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3248 OopClosure* keep_alive, 3249 G1GCPhaseTimes* phase_times) { 3250 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3251 workers()->run_task(&cl); 3252 } 3253 3254 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3255 private: 3256 G1RedirtyCardsQueueSet* _qset; 3257 G1CollectedHeap* _g1h; 3258 BufferNode* volatile _nodes; 3259 3260 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3261 size_t buffer_size = _qset->buffer_size(); 3262 BufferNode* next = Atomic::load(&_nodes); 3263 while (next != NULL) { 3264 BufferNode* node = next; 3265 next = Atomic::cmpxchg(node->next(), &_nodes, node); 3266 if (next == node) { 3267 cl->apply_to_buffer(node, buffer_size, worker_id); 3268 next = node->next(); 3269 } 3270 } 3271 } 3272 3273 public: 3274 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3275 AbstractGangTask("Redirty Cards"), 3276 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3277 3278 virtual void work(uint worker_id) { 3279 G1GCPhaseTimes* p = _g1h->phase_times(); 3280 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3281 3282 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3283 par_apply(&cl, worker_id); 3284 3285 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3286 } 3287 }; 3288 3289 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3290 double redirty_logged_cards_start = os::elapsedTime(); 3291 3292 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3293 workers()->run_task(&redirty_task); 3294 3295 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3296 dcq.merge_bufferlists(rdcqs); 3297 3298 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3299 } 3300 3301 // Weak Reference Processing support 3302 3303 bool G1STWIsAliveClosure::do_object_b(oop p) { 3304 // An object is reachable if it is outside the collection set, 3305 // or is inside and copied. 3306 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3307 } 3308 3309 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3310 assert(obj != NULL, "must not be NULL"); 3311 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3312 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3313 // may falsely indicate that this is not the case here: however the collection set only 3314 // contains old regions when concurrent mark is not running. 3315 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3316 } 3317 3318 // Non Copying Keep Alive closure 3319 class G1KeepAliveClosure: public OopClosure { 3320 G1CollectedHeap*_g1h; 3321 public: 3322 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3323 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3324 void do_oop(oop* p) { 3325 oop obj = *p; 3326 assert(obj != NULL, "the caller should have filtered out NULL values"); 3327 3328 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3329 if (!region_attr.is_in_cset_or_humongous()) { 3330 return; 3331 } 3332 if (region_attr.is_in_cset()) { 3333 assert( obj->is_forwarded(), "invariant" ); 3334 *p = obj->forwardee(); 3335 } else { 3336 assert(!obj->is_forwarded(), "invariant" ); 3337 assert(region_attr.is_humongous(), 3338 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3339 _g1h->set_humongous_is_live(obj); 3340 } 3341 } 3342 }; 3343 3344 // Copying Keep Alive closure - can be called from both 3345 // serial and parallel code as long as different worker 3346 // threads utilize different G1ParScanThreadState instances 3347 // and different queues. 3348 3349 class G1CopyingKeepAliveClosure: public OopClosure { 3350 G1CollectedHeap* _g1h; 3351 G1ParScanThreadState* _par_scan_state; 3352 3353 public: 3354 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3355 G1ParScanThreadState* pss): 3356 _g1h(g1h), 3357 _par_scan_state(pss) 3358 {} 3359 3360 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3361 virtual void do_oop( oop* p) { do_oop_work(p); } 3362 3363 template <class T> void do_oop_work(T* p) { 3364 oop obj = RawAccess<>::oop_load(p); 3365 3366 if (_g1h->is_in_cset_or_humongous(obj)) { 3367 // If the referent object has been forwarded (either copied 3368 // to a new location or to itself in the event of an 3369 // evacuation failure) then we need to update the reference 3370 // field and, if both reference and referent are in the G1 3371 // heap, update the RSet for the referent. 3372 // 3373 // If the referent has not been forwarded then we have to keep 3374 // it alive by policy. Therefore we have copy the referent. 3375 // 3376 // When the queue is drained (after each phase of reference processing) 3377 // the object and it's followers will be copied, the reference field set 3378 // to point to the new location, and the RSet updated. 3379 _par_scan_state->push_on_queue(p); 3380 } 3381 } 3382 }; 3383 3384 // Serial drain queue closure. Called as the 'complete_gc' 3385 // closure for each discovered list in some of the 3386 // reference processing phases. 3387 3388 class G1STWDrainQueueClosure: public VoidClosure { 3389 protected: 3390 G1CollectedHeap* _g1h; 3391 G1ParScanThreadState* _par_scan_state; 3392 3393 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3394 3395 public: 3396 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3397 _g1h(g1h), 3398 _par_scan_state(pss) 3399 { } 3400 3401 void do_void() { 3402 G1ParScanThreadState* const pss = par_scan_state(); 3403 pss->trim_queue(); 3404 } 3405 }; 3406 3407 // Parallel Reference Processing closures 3408 3409 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3410 // processing during G1 evacuation pauses. 3411 3412 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3413 private: 3414 G1CollectedHeap* _g1h; 3415 G1ParScanThreadStateSet* _pss; 3416 RefToScanQueueSet* _queues; 3417 WorkGang* _workers; 3418 3419 public: 3420 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3421 G1ParScanThreadStateSet* per_thread_states, 3422 WorkGang* workers, 3423 RefToScanQueueSet *task_queues) : 3424 _g1h(g1h), 3425 _pss(per_thread_states), 3426 _queues(task_queues), 3427 _workers(workers) 3428 { 3429 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3430 } 3431 3432 // Executes the given task using concurrent marking worker threads. 3433 virtual void execute(ProcessTask& task, uint ergo_workers); 3434 }; 3435 3436 // Gang task for possibly parallel reference processing 3437 3438 class G1STWRefProcTaskProxy: public AbstractGangTask { 3439 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3440 ProcessTask& _proc_task; 3441 G1CollectedHeap* _g1h; 3442 G1ParScanThreadStateSet* _pss; 3443 RefToScanQueueSet* _task_queues; 3444 ParallelTaskTerminator* _terminator; 3445 3446 public: 3447 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3448 G1CollectedHeap* g1h, 3449 G1ParScanThreadStateSet* per_thread_states, 3450 RefToScanQueueSet *task_queues, 3451 ParallelTaskTerminator* terminator) : 3452 AbstractGangTask("Process reference objects in parallel"), 3453 _proc_task(proc_task), 3454 _g1h(g1h), 3455 _pss(per_thread_states), 3456 _task_queues(task_queues), 3457 _terminator(terminator) 3458 {} 3459 3460 virtual void work(uint worker_id) { 3461 // The reference processing task executed by a single worker. 3462 ResourceMark rm; 3463 HandleMark hm; 3464 3465 G1STWIsAliveClosure is_alive(_g1h); 3466 3467 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3468 pss->set_ref_discoverer(NULL); 3469 3470 // Keep alive closure. 3471 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3472 3473 // Complete GC closure 3474 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3475 3476 // Call the reference processing task's work routine. 3477 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3478 3479 // Note we cannot assert that the refs array is empty here as not all 3480 // of the processing tasks (specifically phase2 - pp2_work) execute 3481 // the complete_gc closure (which ordinarily would drain the queue) so 3482 // the queue may not be empty. 3483 } 3484 }; 3485 3486 // Driver routine for parallel reference processing. 3487 // Creates an instance of the ref processing gang 3488 // task and has the worker threads execute it. 3489 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3490 assert(_workers != NULL, "Need parallel worker threads."); 3491 3492 assert(_workers->active_workers() >= ergo_workers, 3493 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3494 ergo_workers, _workers->active_workers()); 3495 TaskTerminator terminator(ergo_workers, _queues); 3496 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3497 3498 _workers->run_task(&proc_task_proxy, ergo_workers); 3499 } 3500 3501 // End of weak reference support closures 3502 3503 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3504 double ref_proc_start = os::elapsedTime(); 3505 3506 ReferenceProcessor* rp = _ref_processor_stw; 3507 assert(rp->discovery_enabled(), "should have been enabled"); 3508 3509 // Closure to test whether a referent is alive. 3510 G1STWIsAliveClosure is_alive(this); 3511 3512 // Even when parallel reference processing is enabled, the processing 3513 // of JNI refs is serial and performed serially by the current thread 3514 // rather than by a worker. The following PSS will be used for processing 3515 // JNI refs. 3516 3517 // Use only a single queue for this PSS. 3518 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3519 pss->set_ref_discoverer(NULL); 3520 assert(pss->queue_is_empty(), "pre-condition"); 3521 3522 // Keep alive closure. 3523 G1CopyingKeepAliveClosure keep_alive(this, pss); 3524 3525 // Serial Complete GC closure 3526 G1STWDrainQueueClosure drain_queue(this, pss); 3527 3528 // Setup the soft refs policy... 3529 rp->setup_policy(false); 3530 3531 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3532 3533 ReferenceProcessorStats stats; 3534 if (!rp->processing_is_mt()) { 3535 // Serial reference processing... 3536 stats = rp->process_discovered_references(&is_alive, 3537 &keep_alive, 3538 &drain_queue, 3539 NULL, 3540 pt); 3541 } else { 3542 uint no_of_gc_workers = workers()->active_workers(); 3543 3544 // Parallel reference processing 3545 assert(no_of_gc_workers <= rp->max_num_queues(), 3546 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3547 no_of_gc_workers, rp->max_num_queues()); 3548 3549 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3550 stats = rp->process_discovered_references(&is_alive, 3551 &keep_alive, 3552 &drain_queue, 3553 &par_task_executor, 3554 pt); 3555 } 3556 3557 _gc_tracer_stw->report_gc_reference_stats(stats); 3558 3559 // We have completed copying any necessary live referent objects. 3560 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3561 3562 make_pending_list_reachable(); 3563 3564 assert(!rp->discovery_enabled(), "Postcondition"); 3565 rp->verify_no_references_recorded(); 3566 3567 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3568 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3569 } 3570 3571 void G1CollectedHeap::make_pending_list_reachable() { 3572 if (collector_state()->in_initial_mark_gc()) { 3573 oop pll_head = Universe::reference_pending_list(); 3574 if (pll_head != NULL) { 3575 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3576 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3577 } 3578 } 3579 } 3580 3581 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3582 double merge_pss_time_start = os::elapsedTime(); 3583 per_thread_states->flush(); 3584 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3585 } 3586 3587 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3588 _expand_heap_after_alloc_failure = true; 3589 _evacuation_failed = false; 3590 3591 // Disable the hot card cache. 3592 _hot_card_cache->reset_hot_cache_claimed_index(); 3593 _hot_card_cache->set_use_cache(false); 3594 3595 // Initialize the GC alloc regions. 3596 _allocator->init_gc_alloc_regions(evacuation_info); 3597 3598 { 3599 Ticks start = Ticks::now(); 3600 rem_set()->prepare_for_scan_heap_roots(); 3601 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3602 } 3603 3604 register_regions_with_region_attr(); 3605 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3606 3607 _preserved_marks_set.assert_empty(); 3608 3609 #if COMPILER2_OR_JVMCI 3610 DerivedPointerTable::clear(); 3611 #endif 3612 3613 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3614 if (collector_state()->in_initial_mark_gc()) { 3615 concurrent_mark()->pre_initial_mark(); 3616 3617 double start_clear_claimed_marks = os::elapsedTime(); 3618 3619 ClassLoaderDataGraph::clear_claimed_marks(); 3620 3621 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3622 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3623 } 3624 3625 // Should G1EvacuationFailureALot be in effect for this GC? 3626 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3627 } 3628 3629 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3630 protected: 3631 G1CollectedHeap* _g1h; 3632 G1ParScanThreadStateSet* _per_thread_states; 3633 RefToScanQueueSet* _task_queues; 3634 TaskTerminator _terminator; 3635 uint _num_workers; 3636 3637 void evacuate_live_objects(G1ParScanThreadState* pss, 3638 uint worker_id, 3639 G1GCPhaseTimes::GCParPhases objcopy_phase, 3640 G1GCPhaseTimes::GCParPhases termination_phase) { 3641 G1GCPhaseTimes* p = _g1h->phase_times(); 3642 3643 Ticks start = Ticks::now(); 3644 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase); 3645 cl.do_void(); 3646 3647 assert(pss->queue_is_empty(), "should be empty"); 3648 3649 Tickspan evac_time = (Ticks::now() - start); 3650 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3651 3652 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste); 3653 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste); 3654 3655 if (termination_phase == G1GCPhaseTimes::Termination) { 3656 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3657 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3658 } else { 3659 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3660 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3661 } 3662 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3663 } 3664 3665 virtual void start_work(uint worker_id) { } 3666 3667 virtual void end_work(uint worker_id) { } 3668 3669 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3670 3671 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3672 3673 public: 3674 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3675 AbstractGangTask(name), 3676 _g1h(G1CollectedHeap::heap()), 3677 _per_thread_states(per_thread_states), 3678 _task_queues(task_queues), 3679 _terminator(num_workers, _task_queues), 3680 _num_workers(num_workers) 3681 { } 3682 3683 void work(uint worker_id) { 3684 start_work(worker_id); 3685 3686 { 3687 ResourceMark rm; 3688 HandleMark hm; 3689 3690 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3691 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3692 3693 scan_roots(pss, worker_id); 3694 evacuate_live_objects(pss, worker_id); 3695 } 3696 3697 end_work(worker_id); 3698 } 3699 }; 3700 3701 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3702 G1RootProcessor* _root_processor; 3703 3704 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3705 _root_processor->evacuate_roots(pss, worker_id); 3706 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3707 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3708 } 3709 3710 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3711 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3712 } 3713 3714 void start_work(uint worker_id) { 3715 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3716 } 3717 3718 void end_work(uint worker_id) { 3719 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3720 } 3721 3722 public: 3723 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3724 G1ParScanThreadStateSet* per_thread_states, 3725 RefToScanQueueSet* task_queues, 3726 G1RootProcessor* root_processor, 3727 uint num_workers) : 3728 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3729 _root_processor(root_processor) 3730 { } 3731 }; 3732 3733 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3734 G1GCPhaseTimes* p = phase_times(); 3735 3736 { 3737 Ticks start = Ticks::now(); 3738 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3739 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3740 } 3741 3742 Tickspan task_time; 3743 const uint num_workers = workers()->active_workers(); 3744 3745 Ticks start_processing = Ticks::now(); 3746 { 3747 G1RootProcessor root_processor(this, num_workers); 3748 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3749 task_time = run_task(&g1_par_task); 3750 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3751 // To extract its code root fixup time we measure total time of this scope and 3752 // subtract from the time the WorkGang task took. 3753 } 3754 Tickspan total_processing = Ticks::now() - start_processing; 3755 3756 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3757 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3758 } 3759 3760 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3761 3762 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3763 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3764 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3765 } 3766 3767 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3768 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3769 } 3770 3771 public: 3772 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3773 RefToScanQueueSet* queues, 3774 uint num_workers) : 3775 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3776 } 3777 }; 3778 3779 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3780 class G1MarkScope : public MarkScope { }; 3781 3782 Tickspan task_time; 3783 3784 Ticks start_processing = Ticks::now(); 3785 { 3786 G1MarkScope code_mark_scope; 3787 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3788 task_time = run_task(&task); 3789 // See comment in evacuate_collection_set() for the reason of the scope. 3790 } 3791 Tickspan total_processing = Ticks::now() - start_processing; 3792 3793 G1GCPhaseTimes* p = phase_times(); 3794 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3795 } 3796 3797 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3798 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3799 3800 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3801 3802 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3803 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3804 3805 if (time_left_ms < 0 || 3806 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3807 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3808 _collection_set.optional_region_length(), time_left_ms); 3809 break; 3810 } 3811 3812 { 3813 Ticks start = Ticks::now(); 3814 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3815 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3816 } 3817 3818 { 3819 Ticks start = Ticks::now(); 3820 evacuate_next_optional_regions(per_thread_states); 3821 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3822 } 3823 } 3824 3825 _collection_set.abandon_optional_collection_set(per_thread_states); 3826 } 3827 3828 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3829 G1RedirtyCardsQueueSet* rdcqs, 3830 G1ParScanThreadStateSet* per_thread_states) { 3831 rem_set()->cleanup_after_scan_heap_roots(); 3832 3833 // Process any discovered reference objects - we have 3834 // to do this _before_ we retire the GC alloc regions 3835 // as we may have to copy some 'reachable' referent 3836 // objects (and their reachable sub-graphs) that were 3837 // not copied during the pause. 3838 process_discovered_references(per_thread_states); 3839 3840 G1STWIsAliveClosure is_alive(this); 3841 G1KeepAliveClosure keep_alive(this); 3842 3843 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3844 phase_times()->weak_phase_times()); 3845 3846 if (G1StringDedup::is_enabled()) { 3847 double string_dedup_time_ms = os::elapsedTime(); 3848 3849 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3850 3851 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3852 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3853 } 3854 3855 _allocator->release_gc_alloc_regions(evacuation_info); 3856 3857 if (evacuation_failed()) { 3858 restore_after_evac_failure(rdcqs); 3859 3860 // Reset the G1EvacuationFailureALot counters and flags 3861 NOT_PRODUCT(reset_evacuation_should_fail();) 3862 3863 double recalculate_used_start = os::elapsedTime(); 3864 set_used(recalculate_used()); 3865 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3866 3867 if (_archive_allocator != NULL) { 3868 _archive_allocator->clear_used(); 3869 } 3870 for (uint i = 0; i < ParallelGCThreads; i++) { 3871 if (_evacuation_failed_info_array[i].has_failed()) { 3872 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3873 } 3874 } 3875 } else { 3876 // The "used" of the the collection set have already been subtracted 3877 // when they were freed. Add in the bytes evacuated. 3878 increase_used(policy()->bytes_copied_during_gc()); 3879 } 3880 3881 _preserved_marks_set.assert_empty(); 3882 3883 merge_per_thread_state_info(per_thread_states); 3884 3885 // Reset and re-enable the hot card cache. 3886 // Note the counts for the cards in the regions in the 3887 // collection set are reset when the collection set is freed. 3888 _hot_card_cache->reset_hot_cache(); 3889 _hot_card_cache->set_use_cache(true); 3890 3891 purge_code_root_memory(); 3892 3893 redirty_logged_cards(rdcqs); 3894 3895 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3896 3897 eagerly_reclaim_humongous_regions(); 3898 3899 record_obj_copy_mem_stats(); 3900 3901 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3902 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3903 3904 #if COMPILER2_OR_JVMCI 3905 double start = os::elapsedTime(); 3906 DerivedPointerTable::update_pointers(); 3907 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3908 #endif 3909 policy()->print_age_table(); 3910 } 3911 3912 void G1CollectedHeap::record_obj_copy_mem_stats() { 3913 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3914 3915 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3916 create_g1_evac_summary(&_old_evac_stats)); 3917 } 3918 3919 void G1CollectedHeap::free_region(HeapRegion* hr, 3920 FreeRegionList* free_list, 3921 bool skip_remset, 3922 bool skip_hot_card_cache, 3923 bool locked) { 3924 assert(!hr->is_free(), "the region should not be free"); 3925 assert(!hr->is_empty(), "the region should not be empty"); 3926 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3927 assert(free_list != NULL, "pre-condition"); 3928 3929 if (G1VerifyBitmaps) { 3930 MemRegion mr(hr->bottom(), hr->end()); 3931 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3932 } 3933 3934 // Clear the card counts for this region. 3935 // Note: we only need to do this if the region is not young 3936 // (since we don't refine cards in young regions). 3937 if (!skip_hot_card_cache && !hr->is_young()) { 3938 _hot_card_cache->reset_card_counts(hr); 3939 } 3940 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3941 _policy->remset_tracker()->update_at_free(hr); 3942 free_list->add_ordered(hr); 3943 } 3944 3945 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3946 FreeRegionList* free_list) { 3947 assert(hr->is_humongous(), "this is only for humongous regions"); 3948 assert(free_list != NULL, "pre-condition"); 3949 hr->clear_humongous(); 3950 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3951 } 3952 3953 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3954 const uint humongous_regions_removed) { 3955 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3956 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3957 _old_set.bulk_remove(old_regions_removed); 3958 _humongous_set.bulk_remove(humongous_regions_removed); 3959 } 3960 3961 } 3962 3963 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3964 assert(list != NULL, "list can't be null"); 3965 if (!list->is_empty()) { 3966 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3967 _hrm->insert_list_into_free_list(list); 3968 } 3969 } 3970 3971 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3972 decrease_used(bytes); 3973 } 3974 3975 class G1FreeCollectionSetTask : public AbstractGangTask { 3976 private: 3977 3978 // Closure applied to all regions in the collection set to do work that needs to 3979 // be done serially in a single thread. 3980 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3981 private: 3982 G1EvacuationInfo* _evacuation_info; 3983 const size_t* _surviving_young_words; 3984 3985 // Bytes used in successfully evacuated regions before the evacuation. 3986 size_t _before_used_bytes; 3987 // Bytes used in unsucessfully evacuated regions before the evacuation 3988 size_t _after_used_bytes; 3989 3990 size_t _bytes_allocated_in_old_since_last_gc; 3991 3992 size_t _failure_used_words; 3993 size_t _failure_waste_words; 3994 3995 FreeRegionList _local_free_list; 3996 public: 3997 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3998 HeapRegionClosure(), 3999 _evacuation_info(evacuation_info), 4000 _surviving_young_words(surviving_young_words), 4001 _before_used_bytes(0), 4002 _after_used_bytes(0), 4003 _bytes_allocated_in_old_since_last_gc(0), 4004 _failure_used_words(0), 4005 _failure_waste_words(0), 4006 _local_free_list("Local Region List for CSet Freeing") { 4007 } 4008 4009 virtual bool do_heap_region(HeapRegion* r) { 4010 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4011 4012 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4013 g1h->clear_region_attr(r); 4014 4015 if (r->is_young()) { 4016 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(), 4017 "Young index %u is wrong for region %u of type %s with %u young regions", 4018 r->young_index_in_cset(), 4019 r->hrm_index(), 4020 r->get_type_str(), 4021 g1h->collection_set()->young_region_length()); 4022 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4023 r->record_surv_words_in_group(words_survived); 4024 } 4025 4026 if (!r->evacuation_failed()) { 4027 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4028 _before_used_bytes += r->used(); 4029 g1h->free_region(r, 4030 &_local_free_list, 4031 true, /* skip_remset */ 4032 true, /* skip_hot_card_cache */ 4033 true /* locked */); 4034 } else { 4035 r->uninstall_surv_rate_group(); 4036 r->clear_young_index_in_cset(); 4037 r->set_evacuation_failed(false); 4038 // When moving a young gen region to old gen, we "allocate" that whole region 4039 // there. This is in addition to any already evacuated objects. Notify the 4040 // policy about that. 4041 // Old gen regions do not cause an additional allocation: both the objects 4042 // still in the region and the ones already moved are accounted for elsewhere. 4043 if (r->is_young()) { 4044 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4045 } 4046 // The region is now considered to be old. 4047 r->set_old(); 4048 // Do some allocation statistics accounting. Regions that failed evacuation 4049 // are always made old, so there is no need to update anything in the young 4050 // gen statistics, but we need to update old gen statistics. 4051 size_t used_words = r->marked_bytes() / HeapWordSize; 4052 4053 _failure_used_words += used_words; 4054 _failure_waste_words += HeapRegion::GrainWords - used_words; 4055 4056 g1h->old_set_add(r); 4057 _after_used_bytes += r->used(); 4058 } 4059 return false; 4060 } 4061 4062 void complete_work() { 4063 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4064 4065 _evacuation_info->set_regions_freed(_local_free_list.length()); 4066 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4067 4068 g1h->prepend_to_freelist(&_local_free_list); 4069 g1h->decrement_summary_bytes(_before_used_bytes); 4070 4071 G1Policy* policy = g1h->policy(); 4072 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4073 4074 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4075 } 4076 }; 4077 4078 G1CollectionSet* _collection_set; 4079 G1SerialFreeCollectionSetClosure _cl; 4080 const size_t* _surviving_young_words; 4081 4082 size_t _rs_length; 4083 4084 volatile jint _serial_work_claim; 4085 4086 struct WorkItem { 4087 uint region_idx; 4088 bool is_young; 4089 bool evacuation_failed; 4090 4091 WorkItem(HeapRegion* r) { 4092 region_idx = r->hrm_index(); 4093 is_young = r->is_young(); 4094 evacuation_failed = r->evacuation_failed(); 4095 } 4096 }; 4097 4098 volatile size_t _parallel_work_claim; 4099 size_t _num_work_items; 4100 WorkItem* _work_items; 4101 4102 void do_serial_work() { 4103 // Need to grab the lock to be allowed to modify the old region list. 4104 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4105 _collection_set->iterate(&_cl); 4106 } 4107 4108 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4109 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4110 4111 HeapRegion* r = g1h->region_at(region_idx); 4112 assert(!g1h->is_on_master_free_list(r), "sanity"); 4113 4114 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length); 4115 4116 if (!is_young) { 4117 g1h->hot_card_cache()->reset_card_counts(r); 4118 } 4119 4120 if (!evacuation_failed) { 4121 r->rem_set()->clear_locked(); 4122 } 4123 } 4124 4125 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4126 private: 4127 size_t _cur_idx; 4128 WorkItem* _work_items; 4129 public: 4130 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4131 4132 virtual bool do_heap_region(HeapRegion* r) { 4133 _work_items[_cur_idx++] = WorkItem(r); 4134 return false; 4135 } 4136 }; 4137 4138 void prepare_work() { 4139 G1PrepareFreeCollectionSetClosure cl(_work_items); 4140 _collection_set->iterate(&cl); 4141 } 4142 4143 void complete_work() { 4144 _cl.complete_work(); 4145 4146 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4147 policy->record_rs_length(_rs_length); 4148 policy->cset_regions_freed(); 4149 } 4150 public: 4151 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4152 AbstractGangTask("G1 Free Collection Set"), 4153 _collection_set(collection_set), 4154 _cl(evacuation_info, surviving_young_words), 4155 _surviving_young_words(surviving_young_words), 4156 _rs_length(0), 4157 _serial_work_claim(0), 4158 _parallel_work_claim(0), 4159 _num_work_items(collection_set->region_length()), 4160 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4161 prepare_work(); 4162 } 4163 4164 ~G1FreeCollectionSetTask() { 4165 complete_work(); 4166 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4167 } 4168 4169 // Chunk size for work distribution. The chosen value has been determined experimentally 4170 // to be a good tradeoff between overhead and achievable parallelism. 4171 static uint chunk_size() { return 32; } 4172 4173 virtual void work(uint worker_id) { 4174 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4175 4176 // Claim serial work. 4177 if (_serial_work_claim == 0) { 4178 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4179 if (value == 0) { 4180 double serial_time = os::elapsedTime(); 4181 do_serial_work(); 4182 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4183 } 4184 } 4185 4186 // Start parallel work. 4187 double young_time = 0.0; 4188 bool has_young_time = false; 4189 double non_young_time = 0.0; 4190 bool has_non_young_time = false; 4191 4192 while (true) { 4193 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4194 size_t cur = end - chunk_size(); 4195 4196 if (cur >= _num_work_items) { 4197 break; 4198 } 4199 4200 EventGCPhaseParallel event; 4201 double start_time = os::elapsedTime(); 4202 4203 end = MIN2(end, _num_work_items); 4204 4205 for (; cur < end; cur++) { 4206 bool is_young = _work_items[cur].is_young; 4207 4208 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4209 4210 double end_time = os::elapsedTime(); 4211 double time_taken = end_time - start_time; 4212 if (is_young) { 4213 young_time += time_taken; 4214 has_young_time = true; 4215 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4216 } else { 4217 non_young_time += time_taken; 4218 has_non_young_time = true; 4219 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4220 } 4221 start_time = end_time; 4222 } 4223 } 4224 4225 if (has_young_time) { 4226 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4227 } 4228 if (has_non_young_time) { 4229 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4230 } 4231 } 4232 }; 4233 4234 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4235 _eden.clear(); 4236 4237 double free_cset_start_time = os::elapsedTime(); 4238 4239 { 4240 uint const num_regions = _collection_set.region_length(); 4241 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4242 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4243 4244 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4245 4246 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4247 cl.name(), num_workers, num_regions); 4248 workers()->run_task(&cl, num_workers); 4249 } 4250 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4251 4252 collection_set->clear(); 4253 } 4254 4255 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4256 private: 4257 FreeRegionList* _free_region_list; 4258 HeapRegionSet* _proxy_set; 4259 uint _humongous_objects_reclaimed; 4260 uint _humongous_regions_reclaimed; 4261 size_t _freed_bytes; 4262 public: 4263 4264 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4265 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4266 } 4267 4268 virtual bool do_heap_region(HeapRegion* r) { 4269 if (!r->is_starts_humongous()) { 4270 return false; 4271 } 4272 4273 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4274 4275 oop obj = (oop)r->bottom(); 4276 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4277 4278 // The following checks whether the humongous object is live are sufficient. 4279 // The main additional check (in addition to having a reference from the roots 4280 // or the young gen) is whether the humongous object has a remembered set entry. 4281 // 4282 // A humongous object cannot be live if there is no remembered set for it 4283 // because: 4284 // - there can be no references from within humongous starts regions referencing 4285 // the object because we never allocate other objects into them. 4286 // (I.e. there are no intra-region references that may be missed by the 4287 // remembered set) 4288 // - as soon there is a remembered set entry to the humongous starts region 4289 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4290 // until the end of a concurrent mark. 4291 // 4292 // It is not required to check whether the object has been found dead by marking 4293 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4294 // all objects allocated during that time are considered live. 4295 // SATB marking is even more conservative than the remembered set. 4296 // So if at this point in the collection there is no remembered set entry, 4297 // nobody has a reference to it. 4298 // At the start of collection we flush all refinement logs, and remembered sets 4299 // are completely up-to-date wrt to references to the humongous object. 4300 // 4301 // Other implementation considerations: 4302 // - never consider object arrays at this time because they would pose 4303 // considerable effort for cleaning up the the remembered sets. This is 4304 // required because stale remembered sets might reference locations that 4305 // are currently allocated into. 4306 uint region_idx = r->hrm_index(); 4307 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4308 !r->rem_set()->is_empty()) { 4309 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 4310 region_idx, 4311 (size_t)obj->size() * HeapWordSize, 4312 p2i(r->bottom()), 4313 r->rem_set()->occupied(), 4314 r->rem_set()->strong_code_roots_list_length(), 4315 next_bitmap->is_marked(r->bottom()), 4316 g1h->is_humongous_reclaim_candidate(region_idx), 4317 obj->is_typeArray() 4318 ); 4319 return false; 4320 } 4321 4322 guarantee(obj->is_typeArray(), 4323 "Only eagerly reclaiming type arrays is supported, but the object " 4324 PTR_FORMAT " is not.", p2i(r->bottom())); 4325 4326 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 4327 region_idx, 4328 (size_t)obj->size() * HeapWordSize, 4329 p2i(r->bottom()), 4330 r->rem_set()->occupied(), 4331 r->rem_set()->strong_code_roots_list_length(), 4332 next_bitmap->is_marked(r->bottom()), 4333 g1h->is_humongous_reclaim_candidate(region_idx), 4334 obj->is_typeArray() 4335 ); 4336 4337 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4338 cm->humongous_object_eagerly_reclaimed(r); 4339 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4340 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4341 region_idx, 4342 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4343 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4344 _humongous_objects_reclaimed++; 4345 do { 4346 HeapRegion* next = g1h->next_region_in_humongous(r); 4347 _freed_bytes += r->used(); 4348 r->set_containing_set(NULL); 4349 _humongous_regions_reclaimed++; 4350 g1h->free_humongous_region(r, _free_region_list); 4351 r = next; 4352 } while (r != NULL); 4353 4354 return false; 4355 } 4356 4357 uint humongous_objects_reclaimed() { 4358 return _humongous_objects_reclaimed; 4359 } 4360 4361 uint humongous_regions_reclaimed() { 4362 return _humongous_regions_reclaimed; 4363 } 4364 4365 size_t bytes_freed() const { 4366 return _freed_bytes; 4367 } 4368 }; 4369 4370 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4371 assert_at_safepoint_on_vm_thread(); 4372 4373 if (!G1EagerReclaimHumongousObjects || 4374 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4375 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4376 return; 4377 } 4378 4379 double start_time = os::elapsedTime(); 4380 4381 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4382 4383 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4384 heap_region_iterate(&cl); 4385 4386 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4387 4388 G1HRPrinter* hrp = hr_printer(); 4389 if (hrp->is_active()) { 4390 FreeRegionListIterator iter(&local_cleanup_list); 4391 while (iter.more_available()) { 4392 HeapRegion* hr = iter.get_next(); 4393 hrp->cleanup(hr); 4394 } 4395 } 4396 4397 prepend_to_freelist(&local_cleanup_list); 4398 decrement_summary_bytes(cl.bytes_freed()); 4399 4400 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4401 cl.humongous_objects_reclaimed()); 4402 } 4403 4404 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4405 public: 4406 virtual bool do_heap_region(HeapRegion* r) { 4407 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4408 G1CollectedHeap::heap()->clear_region_attr(r); 4409 r->clear_young_index_in_cset(); 4410 return false; 4411 } 4412 }; 4413 4414 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4415 G1AbandonCollectionSetClosure cl; 4416 collection_set_iterate_all(&cl); 4417 4418 collection_set->clear(); 4419 collection_set->stop_incremental_building(); 4420 } 4421 4422 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4423 return _allocator->is_retained_old_region(hr); 4424 } 4425 4426 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4427 _eden.add(hr); 4428 _policy->set_region_eden(hr); 4429 } 4430 4431 #ifdef ASSERT 4432 4433 class NoYoungRegionsClosure: public HeapRegionClosure { 4434 private: 4435 bool _success; 4436 public: 4437 NoYoungRegionsClosure() : _success(true) { } 4438 bool do_heap_region(HeapRegion* r) { 4439 if (r->is_young()) { 4440 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4441 p2i(r->bottom()), p2i(r->end())); 4442 _success = false; 4443 } 4444 return false; 4445 } 4446 bool success() { return _success; } 4447 }; 4448 4449 bool G1CollectedHeap::check_young_list_empty() { 4450 bool ret = (young_regions_count() == 0); 4451 4452 NoYoungRegionsClosure closure; 4453 heap_region_iterate(&closure); 4454 ret = ret && closure.success(); 4455 4456 return ret; 4457 } 4458 4459 #endif // ASSERT 4460 4461 class TearDownRegionSetsClosure : public HeapRegionClosure { 4462 HeapRegionSet *_old_set; 4463 4464 public: 4465 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4466 4467 bool do_heap_region(HeapRegion* r) { 4468 if (r->is_old()) { 4469 _old_set->remove(r); 4470 } else if(r->is_young()) { 4471 r->uninstall_surv_rate_group(); 4472 } else { 4473 // We ignore free regions, we'll empty the free list afterwards. 4474 // We ignore humongous and archive regions, we're not tearing down these 4475 // sets. 4476 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4477 "it cannot be another type"); 4478 } 4479 return false; 4480 } 4481 4482 ~TearDownRegionSetsClosure() { 4483 assert(_old_set->is_empty(), "post-condition"); 4484 } 4485 }; 4486 4487 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4488 assert_at_safepoint_on_vm_thread(); 4489 4490 if (!free_list_only) { 4491 TearDownRegionSetsClosure cl(&_old_set); 4492 heap_region_iterate(&cl); 4493 4494 // Note that emptying the _young_list is postponed and instead done as 4495 // the first step when rebuilding the regions sets again. The reason for 4496 // this is that during a full GC string deduplication needs to know if 4497 // a collected region was young or old when the full GC was initiated. 4498 } 4499 _hrm->remove_all_free_regions(); 4500 } 4501 4502 void G1CollectedHeap::increase_used(size_t bytes) { 4503 _summary_bytes_used += bytes; 4504 } 4505 4506 void G1CollectedHeap::decrease_used(size_t bytes) { 4507 assert(_summary_bytes_used >= bytes, 4508 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4509 _summary_bytes_used, bytes); 4510 _summary_bytes_used -= bytes; 4511 } 4512 4513 void G1CollectedHeap::set_used(size_t bytes) { 4514 _summary_bytes_used = bytes; 4515 } 4516 4517 class RebuildRegionSetsClosure : public HeapRegionClosure { 4518 private: 4519 bool _free_list_only; 4520 4521 HeapRegionSet* _old_set; 4522 HeapRegionManager* _hrm; 4523 4524 size_t _total_used; 4525 4526 public: 4527 RebuildRegionSetsClosure(bool free_list_only, 4528 HeapRegionSet* old_set, 4529 HeapRegionManager* hrm) : 4530 _free_list_only(free_list_only), 4531 _old_set(old_set), _hrm(hrm), _total_used(0) { 4532 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4533 if (!free_list_only) { 4534 assert(_old_set->is_empty(), "pre-condition"); 4535 } 4536 } 4537 4538 bool do_heap_region(HeapRegion* r) { 4539 if (r->is_empty()) { 4540 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4541 // Add free regions to the free list 4542 r->set_free(); 4543 _hrm->insert_into_free_list(r); 4544 } else if (!_free_list_only) { 4545 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4546 4547 if (r->is_archive() || r->is_humongous()) { 4548 // We ignore archive and humongous regions. We left these sets unchanged. 4549 } else { 4550 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4551 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4552 r->move_to_old(); 4553 _old_set->add(r); 4554 } 4555 _total_used += r->used(); 4556 } 4557 4558 return false; 4559 } 4560 4561 size_t total_used() { 4562 return _total_used; 4563 } 4564 }; 4565 4566 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4567 assert_at_safepoint_on_vm_thread(); 4568 4569 if (!free_list_only) { 4570 _eden.clear(); 4571 _survivor.clear(); 4572 } 4573 4574 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4575 heap_region_iterate(&cl); 4576 4577 if (!free_list_only) { 4578 set_used(cl.total_used()); 4579 if (_archive_allocator != NULL) { 4580 _archive_allocator->clear_used(); 4581 } 4582 } 4583 assert_used_and_recalculate_used_equal(this); 4584 } 4585 4586 // Methods for the mutator alloc region 4587 4588 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4589 bool force, 4590 uint node_index) { 4591 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4592 bool should_allocate = policy()->should_allocate_mutator_region(); 4593 if (force || should_allocate) { 4594 HeapRegion* new_alloc_region = new_region(word_size, 4595 HeapRegionType::Eden, 4596 false /* do_expand */, 4597 node_index); 4598 if (new_alloc_region != NULL) { 4599 set_region_short_lived_locked(new_alloc_region); 4600 _hr_printer.alloc(new_alloc_region, !should_allocate); 4601 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4602 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4603 return new_alloc_region; 4604 } 4605 } 4606 return NULL; 4607 } 4608 4609 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4610 size_t allocated_bytes) { 4611 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4612 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4613 4614 collection_set()->add_eden_region(alloc_region); 4615 increase_used(allocated_bytes); 4616 _eden.add_used_bytes(allocated_bytes); 4617 _hr_printer.retire(alloc_region); 4618 4619 // We update the eden sizes here, when the region is retired, 4620 // instead of when it's allocated, since this is the point that its 4621 // used space has been recorded in _summary_bytes_used. 4622 g1mm()->update_eden_size(); 4623 } 4624 4625 // Methods for the GC alloc regions 4626 4627 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4628 if (dest.is_old()) { 4629 return true; 4630 } else { 4631 return survivor_regions_count() < policy()->max_survivor_regions(); 4632 } 4633 } 4634 4635 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4636 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4637 4638 if (!has_more_regions(dest)) { 4639 return NULL; 4640 } 4641 4642 HeapRegionType type; 4643 if (dest.is_young()) { 4644 type = HeapRegionType::Survivor; 4645 } else { 4646 type = HeapRegionType::Old; 4647 } 4648 4649 HeapRegion* new_alloc_region = new_region(word_size, 4650 type, 4651 true /* do_expand */, 4652 node_index); 4653 4654 if (new_alloc_region != NULL) { 4655 if (type.is_survivor()) { 4656 new_alloc_region->set_survivor(); 4657 _survivor.add(new_alloc_region); 4658 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4659 } else { 4660 new_alloc_region->set_old(); 4661 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4662 } 4663 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4664 register_region_with_region_attr(new_alloc_region); 4665 _hr_printer.alloc(new_alloc_region); 4666 return new_alloc_region; 4667 } 4668 return NULL; 4669 } 4670 4671 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4672 size_t allocated_bytes, 4673 G1HeapRegionAttr dest) { 4674 policy()->record_bytes_copied_during_gc(allocated_bytes); 4675 if (dest.is_old()) { 4676 old_set_add(alloc_region); 4677 } else { 4678 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4679 _survivor.add_used_bytes(allocated_bytes); 4680 } 4681 4682 bool const during_im = collector_state()->in_initial_mark_gc(); 4683 if (during_im && allocated_bytes > 0) { 4684 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4685 } 4686 _hr_printer.retire(alloc_region); 4687 } 4688 4689 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4690 bool expanded = false; 4691 uint index = _hrm->find_highest_free(&expanded); 4692 4693 if (index != G1_NO_HRM_INDEX) { 4694 if (expanded) { 4695 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4696 HeapRegion::GrainWords * HeapWordSize); 4697 } 4698 _hrm->allocate_free_regions_starting_at(index, 1); 4699 return region_at(index); 4700 } 4701 return NULL; 4702 } 4703 4704 // Optimized nmethod scanning 4705 4706 class RegisterNMethodOopClosure: public OopClosure { 4707 G1CollectedHeap* _g1h; 4708 nmethod* _nm; 4709 4710 template <class T> void do_oop_work(T* p) { 4711 T heap_oop = RawAccess<>::oop_load(p); 4712 if (!CompressedOops::is_null(heap_oop)) { 4713 oop obj = CompressedOops::decode_not_null(heap_oop); 4714 HeapRegion* hr = _g1h->heap_region_containing(obj); 4715 assert(!hr->is_continues_humongous(), 4716 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4717 " starting at " HR_FORMAT, 4718 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4719 4720 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4721 hr->add_strong_code_root_locked(_nm); 4722 } 4723 } 4724 4725 public: 4726 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4727 _g1h(g1h), _nm(nm) {} 4728 4729 void do_oop(oop* p) { do_oop_work(p); } 4730 void do_oop(narrowOop* p) { do_oop_work(p); } 4731 }; 4732 4733 class UnregisterNMethodOopClosure: public OopClosure { 4734 G1CollectedHeap* _g1h; 4735 nmethod* _nm; 4736 4737 template <class T> void do_oop_work(T* p) { 4738 T heap_oop = RawAccess<>::oop_load(p); 4739 if (!CompressedOops::is_null(heap_oop)) { 4740 oop obj = CompressedOops::decode_not_null(heap_oop); 4741 HeapRegion* hr = _g1h->heap_region_containing(obj); 4742 assert(!hr->is_continues_humongous(), 4743 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4744 " starting at " HR_FORMAT, 4745 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4746 4747 hr->remove_strong_code_root(_nm); 4748 } 4749 } 4750 4751 public: 4752 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4753 _g1h(g1h), _nm(nm) {} 4754 4755 void do_oop(oop* p) { do_oop_work(p); } 4756 void do_oop(narrowOop* p) { do_oop_work(p); } 4757 }; 4758 4759 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4760 guarantee(nm != NULL, "sanity"); 4761 RegisterNMethodOopClosure reg_cl(this, nm); 4762 nm->oops_do(®_cl); 4763 } 4764 4765 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4766 guarantee(nm != NULL, "sanity"); 4767 UnregisterNMethodOopClosure reg_cl(this, nm); 4768 nm->oops_do(®_cl, true); 4769 } 4770 4771 void G1CollectedHeap::purge_code_root_memory() { 4772 double purge_start = os::elapsedTime(); 4773 G1CodeRootSet::purge(); 4774 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4775 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4776 } 4777 4778 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4779 G1CollectedHeap* _g1h; 4780 4781 public: 4782 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4783 _g1h(g1h) {} 4784 4785 void do_code_blob(CodeBlob* cb) { 4786 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4787 if (nm == NULL) { 4788 return; 4789 } 4790 4791 _g1h->register_nmethod(nm); 4792 } 4793 }; 4794 4795 void G1CollectedHeap::rebuild_strong_code_roots() { 4796 RebuildStrongCodeRootClosure blob_cl(this); 4797 CodeCache::blobs_do(&blob_cl); 4798 } 4799 4800 void G1CollectedHeap::initialize_serviceability() { 4801 _g1mm->initialize_serviceability(); 4802 } 4803 4804 MemoryUsage G1CollectedHeap::memory_usage() { 4805 return _g1mm->memory_usage(); 4806 } 4807 4808 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4809 return _g1mm->memory_managers(); 4810 } 4811 4812 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4813 return _g1mm->memory_pools(); 4814 }