1 /* 2 * Copyright (c) 2001, 2020, 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/concurrentGCBreakpoints.hpp" 70 #include "gc/shared/gcBehaviours.hpp" 71 #include "gc/shared/gcHeapSummary.hpp" 72 #include "gc/shared/gcId.hpp" 73 #include "gc/shared/gcLocker.hpp" 74 #include "gc/shared/gcTimer.hpp" 75 #include "gc/shared/gcTraceTime.inline.hpp" 76 #include "gc/shared/generationSpec.hpp" 77 #include "gc/shared/isGCActiveMark.hpp" 78 #include "gc/shared/locationPrinter.inline.hpp" 79 #include "gc/shared/oopStorageParState.hpp" 80 #include "gc/shared/preservedMarks.inline.hpp" 81 #include "gc/shared/suspendibleThreadSet.hpp" 82 #include "gc/shared/referenceProcessor.inline.hpp" 83 #include "gc/shared/taskTerminator.hpp" 84 #include "gc/shared/taskqueue.inline.hpp" 85 #include "gc/shared/weakProcessor.inline.hpp" 86 #include "gc/shared/workerPolicy.hpp" 87 #include "logging/log.hpp" 88 #include "memory/allocation.hpp" 89 #include "memory/iterator.hpp" 90 #include "memory/resourceArea.hpp" 91 #include "memory/universe.hpp" 92 #include "oops/access.inline.hpp" 93 #include "oops/compressedOops.inline.hpp" 94 #include "oops/oop.inline.hpp" 95 #include "runtime/atomic.hpp" 96 #include "runtime/flags/flagSetting.hpp" 97 #include "runtime/handles.inline.hpp" 98 #include "runtime/init.hpp" 99 #include "runtime/orderAccess.hpp" 100 #include "runtime/threadSMR.hpp" 101 #include "runtime/vmThread.hpp" 102 #include "utilities/align.hpp" 103 #include "utilities/bitMap.inline.hpp" 104 #include "utilities/globalDefinitions.hpp" 105 #include "utilities/stack.inline.hpp" 106 107 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 108 109 // INVARIANTS/NOTES 110 // 111 // All allocation activity covered by the G1CollectedHeap interface is 112 // serialized by acquiring the HeapLock. This happens in mem_allocate 113 // and allocate_new_tlab, which are the "entry" points to the 114 // allocation code from the rest of the JVM. (Note that this does not 115 // apply to TLAB allocation, which is not part of this interface: it 116 // is done by clients of this interface.) 117 118 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 119 private: 120 size_t _num_dirtied; 121 G1CollectedHeap* _g1h; 122 G1CardTable* _g1_ct; 123 124 HeapRegion* region_for_card(CardValue* card_ptr) const { 125 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 126 } 127 128 bool will_become_free(HeapRegion* hr) const { 129 // A region will be freed by free_collection_set if the region is in the 130 // collection set and has not had an evacuation failure. 131 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 132 } 133 134 public: 135 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 136 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 137 138 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 139 HeapRegion* hr = region_for_card(card_ptr); 140 141 // Should only dirty cards in regions that won't be freed. 142 if (!will_become_free(hr)) { 143 *card_ptr = G1CardTable::dirty_card_val(); 144 _num_dirtied++; 145 } 146 } 147 148 size_t num_dirtied() const { return _num_dirtied; } 149 }; 150 151 152 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 153 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 154 } 155 156 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 157 // The from card cache is not the memory that is actually committed. So we cannot 158 // take advantage of the zero_filled parameter. 159 reset_from_card_cache(start_idx, num_regions); 160 } 161 162 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 163 Ticks start = Ticks::now(); 164 workers()->run_task(task, workers()->active_workers()); 165 return Ticks::now() - start; 166 } 167 168 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 169 MemRegion mr) { 170 return new HeapRegion(hrs_index, bot(), mr); 171 } 172 173 // Private methods. 174 175 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 176 HeapRegionType type, 177 bool do_expand, 178 uint node_index) { 179 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 180 "the only time we use this to allocate a humongous region is " 181 "when we are allocating a single humongous region"); 182 183 HeapRegion* res = _hrm->allocate_free_region(type, node_index); 184 185 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 186 // Currently, only attempts to allocate GC alloc regions set 187 // do_expand to true. So, we should only reach here during a 188 // safepoint. If this assumption changes we might have to 189 // reconsider the use of _expand_heap_after_alloc_failure. 190 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 191 192 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 193 word_size * HeapWordSize); 194 195 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 196 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 197 word_size * HeapWordSize); 198 if (expand_single_region(node_index)) { 199 // Given that expand_single_region() succeeded in expanding the heap, and we 200 // always expand the heap by an amount aligned to the heap 201 // region size, the free list should in theory not be empty. 202 // In either case allocate_free_region() will check for NULL. 203 res = _hrm->allocate_free_region(type, node_index); 204 } else { 205 _expand_heap_after_alloc_failure = false; 206 } 207 } 208 return res; 209 } 210 211 HeapWord* 212 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 213 uint num_regions, 214 size_t word_size) { 215 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 216 assert(is_humongous(word_size), "word_size should be humongous"); 217 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 218 219 // Index of last region in the series. 220 uint last = first + num_regions - 1; 221 222 // We need to initialize the region(s) we just discovered. This is 223 // a bit tricky given that it can happen concurrently with 224 // refinement threads refining cards on these regions and 225 // potentially wanting to refine the BOT as they are scanning 226 // those cards (this can happen shortly after a cleanup; see CR 227 // 6991377). So we have to set up the region(s) carefully and in 228 // a specific order. 229 230 // The word size sum of all the regions we will allocate. 231 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 232 assert(word_size <= word_size_sum, "sanity"); 233 234 // This will be the "starts humongous" region. 235 HeapRegion* first_hr = region_at(first); 236 // The header of the new object will be placed at the bottom of 237 // the first region. 238 HeapWord* new_obj = first_hr->bottom(); 239 // This will be the new top of the new object. 240 HeapWord* obj_top = new_obj + word_size; 241 242 // First, we need to zero the header of the space that we will be 243 // allocating. When we update top further down, some refinement 244 // threads might try to scan the region. By zeroing the header we 245 // ensure that any thread that will try to scan the region will 246 // come across the zero klass word and bail out. 247 // 248 // NOTE: It would not have been correct to have used 249 // CollectedHeap::fill_with_object() and make the space look like 250 // an int array. The thread that is doing the allocation will 251 // later update the object header to a potentially different array 252 // type and, for a very short period of time, the klass and length 253 // fields will be inconsistent. This could cause a refinement 254 // thread to calculate the object size incorrectly. 255 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 256 257 // Next, pad out the unused tail of the last region with filler 258 // objects, for improved usage accounting. 259 // How many words we use for filler objects. 260 size_t word_fill_size = word_size_sum - word_size; 261 262 // How many words memory we "waste" which cannot hold a filler object. 263 size_t words_not_fillable = 0; 264 265 if (word_fill_size >= min_fill_size()) { 266 fill_with_objects(obj_top, word_fill_size); 267 } else if (word_fill_size > 0) { 268 // We have space to fill, but we cannot fit an object there. 269 words_not_fillable = word_fill_size; 270 word_fill_size = 0; 271 } 272 273 // We will set up the first region as "starts humongous". This 274 // will also update the BOT covering all the regions to reflect 275 // that there is a single object that starts at the bottom of the 276 // first region. 277 first_hr->set_starts_humongous(obj_top, word_fill_size); 278 _policy->remset_tracker()->update_at_allocate(first_hr); 279 // Then, if there are any, we will set up the "continues 280 // humongous" regions. 281 HeapRegion* hr = NULL; 282 for (uint i = first + 1; i <= last; ++i) { 283 hr = region_at(i); 284 hr->set_continues_humongous(first_hr); 285 _policy->remset_tracker()->update_at_allocate(hr); 286 } 287 288 // Up to this point no concurrent thread would have been able to 289 // do any scanning on any region in this series. All the top 290 // fields still point to bottom, so the intersection between 291 // [bottom,top] and [card_start,card_end] will be empty. Before we 292 // update the top fields, we'll do a storestore to make sure that 293 // no thread sees the update to top before the zeroing of the 294 // object header and the BOT initialization. 295 OrderAccess::storestore(); 296 297 // Now, we will update the top fields of the "continues humongous" 298 // regions except the last one. 299 for (uint i = first; i < last; ++i) { 300 hr = region_at(i); 301 hr->set_top(hr->end()); 302 } 303 304 hr = region_at(last); 305 // If we cannot fit a filler object, we must set top to the end 306 // of the humongous object, otherwise we cannot iterate the heap 307 // and the BOT will not be complete. 308 hr->set_top(hr->end() - words_not_fillable); 309 310 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 311 "obj_top should be in last region"); 312 313 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 314 315 assert(words_not_fillable == 0 || 316 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 317 "Miscalculation in humongous allocation"); 318 319 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 320 321 for (uint i = first; i <= last; ++i) { 322 hr = region_at(i); 323 _humongous_set.add(hr); 324 _hr_printer.alloc(hr); 325 } 326 327 return new_obj; 328 } 329 330 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 331 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 332 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 333 } 334 335 // If could fit into free regions w/o expansion, try. 336 // Otherwise, if can expand, do so. 337 // Otherwise, if using ex regions might help, try with ex given back. 338 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 339 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 340 341 _verifier->verify_region_sets_optional(); 342 343 uint first = G1_NO_HRM_INDEX; 344 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 345 346 if (obj_regions == 1) { 347 // Only one region to allocate, try to use a fast path by directly allocating 348 // from the free lists. Do not try to expand here, we will potentially do that 349 // later. 350 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 351 if (hr != NULL) { 352 first = hr->hrm_index(); 353 } 354 } else { 355 // Policy: Try only empty regions (i.e. already committed first). Maybe we 356 // are lucky enough to find some. 357 first = _hrm->find_contiguous_only_empty(obj_regions); 358 if (first != G1_NO_HRM_INDEX) { 359 _hrm->allocate_free_regions_starting_at(first, obj_regions); 360 } 361 } 362 363 if (first == G1_NO_HRM_INDEX) { 364 // Policy: We could not find enough regions for the humongous object in the 365 // free list. Look through the heap to find a mix of free and uncommitted regions. 366 // If so, try expansion. 367 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 368 if (first != G1_NO_HRM_INDEX) { 369 // We found something. Make sure these regions are committed, i.e. expand 370 // the heap. Alternatively we could do a defragmentation GC. 371 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 372 word_size * HeapWordSize); 373 374 _hrm->expand_at(first, obj_regions, workers()); 375 policy()->record_new_heap_size(num_regions()); 376 377 #ifdef ASSERT 378 for (uint i = first; i < first + obj_regions; ++i) { 379 HeapRegion* hr = region_at(i); 380 assert(hr->is_free(), "sanity"); 381 assert(hr->is_empty(), "sanity"); 382 assert(is_on_master_free_list(hr), "sanity"); 383 } 384 #endif 385 _hrm->allocate_free_regions_starting_at(first, obj_regions); 386 } else { 387 // Policy: Potentially trigger a defragmentation GC. 388 } 389 } 390 391 HeapWord* result = NULL; 392 if (first != G1_NO_HRM_INDEX) { 393 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 394 assert(result != NULL, "it should always return a valid result"); 395 396 // A successful humongous object allocation changes the used space 397 // information of the old generation so we need to recalculate the 398 // sizes and update the jstat counters here. 399 g1mm()->update_sizes(); 400 } 401 402 _verifier->verify_region_sets_optional(); 403 404 return result; 405 } 406 407 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 408 size_t requested_size, 409 size_t* actual_size) { 410 assert_heap_not_locked_and_not_at_safepoint(); 411 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 412 413 return attempt_allocation(min_size, requested_size, actual_size); 414 } 415 416 HeapWord* 417 G1CollectedHeap::mem_allocate(size_t word_size, 418 bool* gc_overhead_limit_was_exceeded) { 419 assert_heap_not_locked_and_not_at_safepoint(); 420 421 if (is_humongous(word_size)) { 422 return attempt_allocation_humongous(word_size); 423 } 424 size_t dummy = 0; 425 return attempt_allocation(word_size, word_size, &dummy); 426 } 427 428 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 429 ResourceMark rm; // For retrieving the thread names in log messages. 430 431 // Make sure you read the note in attempt_allocation_humongous(). 432 433 assert_heap_not_locked_and_not_at_safepoint(); 434 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 435 "be called for humongous allocation requests"); 436 437 // We should only get here after the first-level allocation attempt 438 // (attempt_allocation()) failed to allocate. 439 440 // We will loop until a) we manage to successfully perform the 441 // allocation or b) we successfully schedule a collection which 442 // fails to perform the allocation. b) is the only case when we'll 443 // return NULL. 444 HeapWord* result = NULL; 445 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 446 bool should_try_gc; 447 uint gc_count_before; 448 449 { 450 MutexLocker x(Heap_lock); 451 result = _allocator->attempt_allocation_locked(word_size); 452 if (result != NULL) { 453 return result; 454 } 455 456 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 457 // This is different to when only GCLocker::needs_gc() is set: try to avoid 458 // waiting because the GCLocker is active to not wait too long. 459 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 460 // No need for an ergo message here, can_expand_young_list() does this when 461 // it returns true. 462 result = _allocator->attempt_allocation_force(word_size); 463 if (result != NULL) { 464 return result; 465 } 466 } 467 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 468 // the GCLocker initiated GC has been performed and then retry. This includes 469 // the case when the GC Locker is not active but has not been performed. 470 should_try_gc = !GCLocker::needs_gc(); 471 // Read the GC count while still holding the Heap_lock. 472 gc_count_before = total_collections(); 473 } 474 475 if (should_try_gc) { 476 bool succeeded; 477 result = do_collection_pause(word_size, gc_count_before, &succeeded, 478 GCCause::_g1_inc_collection_pause); 479 if (result != NULL) { 480 assert(succeeded, "only way to get back a non-NULL result"); 481 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 482 Thread::current()->name(), p2i(result)); 483 return result; 484 } 485 486 if (succeeded) { 487 // We successfully scheduled a collection which failed to allocate. No 488 // point in trying to allocate further. We'll just return NULL. 489 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 490 SIZE_FORMAT " words", Thread::current()->name(), word_size); 491 return NULL; 492 } 493 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 494 Thread::current()->name(), word_size); 495 } else { 496 // Failed to schedule a collection. 497 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 498 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 499 SIZE_FORMAT " words", Thread::current()->name(), word_size); 500 return NULL; 501 } 502 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 503 // The GCLocker is either active or the GCLocker initiated 504 // GC has not yet been performed. Stall until it is and 505 // then retry the allocation. 506 GCLocker::stall_until_clear(); 507 gclocker_retry_count += 1; 508 } 509 510 // We can reach here if we were unsuccessful in scheduling a 511 // collection (because another thread beat us to it) or if we were 512 // stalled due to the GC locker. In either can we should retry the 513 // allocation attempt in case another thread successfully 514 // performed a collection and reclaimed enough space. We do the 515 // first attempt (without holding the Heap_lock) here and the 516 // follow-on attempt will be at the start of the next loop 517 // iteration (after taking the Heap_lock). 518 size_t dummy = 0; 519 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 520 if (result != NULL) { 521 return result; 522 } 523 524 // Give a warning if we seem to be looping forever. 525 if ((QueuedAllocationWarningCount > 0) && 526 (try_count % QueuedAllocationWarningCount == 0)) { 527 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 528 Thread::current()->name(), try_count, word_size); 529 } 530 } 531 532 ShouldNotReachHere(); 533 return NULL; 534 } 535 536 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 537 assert_at_safepoint_on_vm_thread(); 538 if (_archive_allocator == NULL) { 539 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 540 } 541 } 542 543 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 544 // Allocations in archive regions cannot be of a size that would be considered 545 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 546 // may be different at archive-restore time. 547 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 548 } 549 550 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 551 assert_at_safepoint_on_vm_thread(); 552 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 553 if (is_archive_alloc_too_large(word_size)) { 554 return NULL; 555 } 556 return _archive_allocator->archive_mem_allocate(word_size); 557 } 558 559 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 560 size_t end_alignment_in_bytes) { 561 assert_at_safepoint_on_vm_thread(); 562 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 563 564 // Call complete_archive to do the real work, filling in the MemRegion 565 // array with the archive regions. 566 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 567 delete _archive_allocator; 568 _archive_allocator = NULL; 569 } 570 571 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 572 assert(ranges != NULL, "MemRegion array NULL"); 573 assert(count != 0, "No MemRegions provided"); 574 MemRegion reserved = _hrm->reserved(); 575 for (size_t i = 0; i < count; i++) { 576 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 577 return false; 578 } 579 } 580 return true; 581 } 582 583 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 584 size_t count, 585 bool open) { 586 assert(!is_init_completed(), "Expect to be called at JVM init time"); 587 assert(ranges != NULL, "MemRegion array NULL"); 588 assert(count != 0, "No MemRegions provided"); 589 MutexLocker x(Heap_lock); 590 591 MemRegion reserved = _hrm->reserved(); 592 HeapWord* prev_last_addr = NULL; 593 HeapRegion* prev_last_region = NULL; 594 595 // Temporarily disable pretouching of heap pages. This interface is used 596 // when mmap'ing archived heap data in, so pre-touching is wasted. 597 FlagSetting fs(AlwaysPreTouch, false); 598 599 // Enable archive object checking used by G1MarkSweep. We have to let it know 600 // about each archive range, so that objects in those ranges aren't marked. 601 G1ArchiveAllocator::enable_archive_object_check(); 602 603 // For each specified MemRegion range, allocate the corresponding G1 604 // regions and mark them as archive regions. We expect the ranges 605 // in ascending starting address order, without overlap. 606 for (size_t i = 0; i < count; i++) { 607 MemRegion curr_range = ranges[i]; 608 HeapWord* start_address = curr_range.start(); 609 size_t word_size = curr_range.word_size(); 610 HeapWord* last_address = curr_range.last(); 611 size_t commits = 0; 612 613 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 614 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 615 p2i(start_address), p2i(last_address)); 616 guarantee(start_address > prev_last_addr, 617 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 618 p2i(start_address), p2i(prev_last_addr)); 619 prev_last_addr = last_address; 620 621 // Check for ranges that start in the same G1 region in which the previous 622 // range ended, and adjust the start address so we don't try to allocate 623 // the same region again. If the current range is entirely within that 624 // region, skip it, just adjusting the recorded top. 625 HeapRegion* start_region = _hrm->addr_to_region(start_address); 626 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 627 start_address = start_region->end(); 628 if (start_address > last_address) { 629 increase_used(word_size * HeapWordSize); 630 start_region->set_top(last_address + 1); 631 continue; 632 } 633 start_region->set_top(start_address); 634 curr_range = MemRegion(start_address, last_address + 1); 635 start_region = _hrm->addr_to_region(start_address); 636 } 637 638 // Perform the actual region allocation, exiting if it fails. 639 // Then note how much new space we have allocated. 640 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 641 return false; 642 } 643 increase_used(word_size * HeapWordSize); 644 if (commits != 0) { 645 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 646 HeapRegion::GrainWords * HeapWordSize * commits); 647 648 } 649 650 // Mark each G1 region touched by the range as archive, add it to 651 // the old set, and set top. 652 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 653 HeapRegion* last_region = _hrm->addr_to_region(last_address); 654 prev_last_region = last_region; 655 656 while (curr_region != NULL) { 657 assert(curr_region->is_empty() && !curr_region->is_pinned(), 658 "Region already in use (index %u)", curr_region->hrm_index()); 659 if (open) { 660 curr_region->set_open_archive(); 661 } else { 662 curr_region->set_closed_archive(); 663 } 664 _hr_printer.alloc(curr_region); 665 _archive_set.add(curr_region); 666 HeapWord* top; 667 HeapRegion* next_region; 668 if (curr_region != last_region) { 669 top = curr_region->end(); 670 next_region = _hrm->next_region_in_heap(curr_region); 671 } else { 672 top = last_address + 1; 673 next_region = NULL; 674 } 675 curr_region->set_top(top); 676 curr_region = next_region; 677 } 678 679 // Notify mark-sweep of the archive 680 G1ArchiveAllocator::set_range_archive(curr_range, open); 681 } 682 return true; 683 } 684 685 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 686 assert(!is_init_completed(), "Expect to be called at JVM init time"); 687 assert(ranges != NULL, "MemRegion array NULL"); 688 assert(count != 0, "No MemRegions provided"); 689 MemRegion reserved = _hrm->reserved(); 690 HeapWord *prev_last_addr = NULL; 691 HeapRegion* prev_last_region = NULL; 692 693 // For each MemRegion, create filler objects, if needed, in the G1 regions 694 // that contain the address range. The address range actually within the 695 // MemRegion will not be modified. That is assumed to have been initialized 696 // elsewhere, probably via an mmap of archived heap data. 697 MutexLocker x(Heap_lock); 698 for (size_t i = 0; i < count; i++) { 699 HeapWord* start_address = ranges[i].start(); 700 HeapWord* last_address = ranges[i].last(); 701 702 assert(reserved.contains(start_address) && reserved.contains(last_address), 703 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 704 p2i(start_address), p2i(last_address)); 705 assert(start_address > prev_last_addr, 706 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 707 p2i(start_address), p2i(prev_last_addr)); 708 709 HeapRegion* start_region = _hrm->addr_to_region(start_address); 710 HeapRegion* last_region = _hrm->addr_to_region(last_address); 711 HeapWord* bottom_address = start_region->bottom(); 712 713 // Check for a range beginning in the same region in which the 714 // previous one ended. 715 if (start_region == prev_last_region) { 716 bottom_address = prev_last_addr + 1; 717 } 718 719 // Verify that the regions were all marked as archive regions by 720 // alloc_archive_regions. 721 HeapRegion* curr_region = start_region; 722 while (curr_region != NULL) { 723 guarantee(curr_region->is_archive(), 724 "Expected archive region at index %u", curr_region->hrm_index()); 725 if (curr_region != last_region) { 726 curr_region = _hrm->next_region_in_heap(curr_region); 727 } else { 728 curr_region = NULL; 729 } 730 } 731 732 prev_last_addr = last_address; 733 prev_last_region = last_region; 734 735 // Fill the memory below the allocated range with dummy object(s), 736 // if the region bottom does not match the range start, or if the previous 737 // range ended within the same G1 region, and there is a gap. 738 if (start_address != bottom_address) { 739 size_t fill_size = pointer_delta(start_address, bottom_address); 740 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 741 increase_used(fill_size * HeapWordSize); 742 } 743 } 744 } 745 746 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 747 size_t desired_word_size, 748 size_t* actual_word_size) { 749 assert_heap_not_locked_and_not_at_safepoint(); 750 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 751 "be called for humongous allocation requests"); 752 753 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 754 755 if (result == NULL) { 756 *actual_word_size = desired_word_size; 757 result = attempt_allocation_slow(desired_word_size); 758 } 759 760 assert_heap_not_locked(); 761 if (result != NULL) { 762 assert(*actual_word_size != 0, "Actual size must have been set here"); 763 dirty_young_block(result, *actual_word_size); 764 } else { 765 *actual_word_size = 0; 766 } 767 768 return result; 769 } 770 771 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 772 assert(!is_init_completed(), "Expect to be called at JVM init time"); 773 assert(ranges != NULL, "MemRegion array NULL"); 774 assert(count != 0, "No MemRegions provided"); 775 MemRegion reserved = _hrm->reserved(); 776 HeapWord* prev_last_addr = NULL; 777 HeapRegion* prev_last_region = NULL; 778 size_t size_used = 0; 779 size_t uncommitted_regions = 0; 780 781 // For each Memregion, free the G1 regions that constitute it, and 782 // notify mark-sweep that the range is no longer to be considered 'archive.' 783 MutexLocker x(Heap_lock); 784 for (size_t i = 0; i < count; i++) { 785 HeapWord* start_address = ranges[i].start(); 786 HeapWord* last_address = ranges[i].last(); 787 788 assert(reserved.contains(start_address) && reserved.contains(last_address), 789 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 790 p2i(start_address), p2i(last_address)); 791 assert(start_address > prev_last_addr, 792 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 793 p2i(start_address), p2i(prev_last_addr)); 794 size_used += ranges[i].byte_size(); 795 prev_last_addr = last_address; 796 797 HeapRegion* start_region = _hrm->addr_to_region(start_address); 798 HeapRegion* last_region = _hrm->addr_to_region(last_address); 799 800 // Check for ranges that start in the same G1 region in which the previous 801 // range ended, and adjust the start address so we don't try to free 802 // the same region again. If the current range is entirely within that 803 // region, skip it. 804 if (start_region == prev_last_region) { 805 start_address = start_region->end(); 806 if (start_address > last_address) { 807 continue; 808 } 809 start_region = _hrm->addr_to_region(start_address); 810 } 811 prev_last_region = last_region; 812 813 // After verifying that each region was marked as an archive region by 814 // alloc_archive_regions, set it free and empty and uncommit it. 815 HeapRegion* curr_region = start_region; 816 while (curr_region != NULL) { 817 guarantee(curr_region->is_archive(), 818 "Expected archive region at index %u", curr_region->hrm_index()); 819 uint curr_index = curr_region->hrm_index(); 820 _archive_set.remove(curr_region); 821 curr_region->set_free(); 822 curr_region->set_top(curr_region->bottom()); 823 if (curr_region != last_region) { 824 curr_region = _hrm->next_region_in_heap(curr_region); 825 } else { 826 curr_region = NULL; 827 } 828 _hrm->shrink_at(curr_index, 1); 829 uncommitted_regions++; 830 } 831 832 // Notify mark-sweep that this is no longer an archive range. 833 G1ArchiveAllocator::clear_range_archive(ranges[i]); 834 } 835 836 if (uncommitted_regions != 0) { 837 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 838 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 839 } 840 decrease_used(size_used); 841 } 842 843 oop G1CollectedHeap::materialize_archived_object(oop obj) { 844 assert(obj != NULL, "archived obj is NULL"); 845 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 846 847 // Loading an archived object makes it strongly reachable. If it is 848 // loaded during concurrent marking, it must be enqueued to the SATB 849 // queue, shading the previously white object gray. 850 G1BarrierSet::enqueue(obj); 851 852 return obj; 853 } 854 855 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 856 ResourceMark rm; // For retrieving the thread names in log messages. 857 858 // The structure of this method has a lot of similarities to 859 // attempt_allocation_slow(). The reason these two were not merged 860 // into a single one is that such a method would require several "if 861 // allocation is not humongous do this, otherwise do that" 862 // conditional paths which would obscure its flow. In fact, an early 863 // version of this code did use a unified method which was harder to 864 // follow and, as a result, it had subtle bugs that were hard to 865 // track down. So keeping these two methods separate allows each to 866 // be more readable. It will be good to keep these two in sync as 867 // much as possible. 868 869 assert_heap_not_locked_and_not_at_safepoint(); 870 assert(is_humongous(word_size), "attempt_allocation_humongous() " 871 "should only be called for humongous allocations"); 872 873 // Humongous objects can exhaust the heap quickly, so we should check if we 874 // need to start a marking cycle at each humongous object allocation. We do 875 // the check before we do the actual allocation. The reason for doing it 876 // before the allocation is that we avoid having to keep track of the newly 877 // allocated memory while we do a GC. 878 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 879 word_size)) { 880 collect(GCCause::_g1_humongous_allocation); 881 } 882 883 // We will loop until a) we manage to successfully perform the 884 // allocation or b) we successfully schedule a collection which 885 // fails to perform the allocation. b) is the only case when we'll 886 // return NULL. 887 HeapWord* result = NULL; 888 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 889 bool should_try_gc; 890 uint gc_count_before; 891 892 893 { 894 MutexLocker x(Heap_lock); 895 896 // Given that humongous objects are not allocated in young 897 // regions, we'll first try to do the allocation without doing a 898 // collection hoping that there's enough space in the heap. 899 result = humongous_obj_allocate(word_size); 900 if (result != NULL) { 901 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 902 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 903 return result; 904 } 905 906 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 907 // the GCLocker initiated GC has been performed and then retry. This includes 908 // the case when the GC Locker is not active but has not been performed. 909 should_try_gc = !GCLocker::needs_gc(); 910 // Read the GC count while still holding the Heap_lock. 911 gc_count_before = total_collections(); 912 } 913 914 if (should_try_gc) { 915 bool succeeded; 916 result = do_collection_pause(word_size, gc_count_before, &succeeded, 917 GCCause::_g1_humongous_allocation); 918 if (result != NULL) { 919 assert(succeeded, "only way to get back a non-NULL result"); 920 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 921 Thread::current()->name(), p2i(result)); 922 return result; 923 } 924 925 if (succeeded) { 926 // We successfully scheduled a collection which failed to allocate. No 927 // point in trying to allocate further. We'll just return NULL. 928 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 929 SIZE_FORMAT " words", Thread::current()->name(), word_size); 930 return NULL; 931 } 932 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 933 Thread::current()->name(), word_size); 934 } else { 935 // Failed to schedule a collection. 936 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 937 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 938 SIZE_FORMAT " words", Thread::current()->name(), word_size); 939 return NULL; 940 } 941 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 942 // The GCLocker is either active or the GCLocker initiated 943 // GC has not yet been performed. Stall until it is and 944 // then retry the allocation. 945 GCLocker::stall_until_clear(); 946 gclocker_retry_count += 1; 947 } 948 949 950 // We can reach here if we were unsuccessful in scheduling a 951 // collection (because another thread beat us to it) or if we were 952 // stalled due to the GC locker. In either can we should retry the 953 // allocation attempt in case another thread successfully 954 // performed a collection and reclaimed enough space. 955 // Humongous object allocation always needs a lock, so we wait for the retry 956 // in the next iteration of the loop, unlike for the regular iteration case. 957 // Give a warning if we seem to be looping forever. 958 959 if ((QueuedAllocationWarningCount > 0) && 960 (try_count % QueuedAllocationWarningCount == 0)) { 961 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 962 Thread::current()->name(), try_count, word_size); 963 } 964 } 965 966 ShouldNotReachHere(); 967 return NULL; 968 } 969 970 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 971 bool expect_null_mutator_alloc_region) { 972 assert_at_safepoint_on_vm_thread(); 973 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 974 "the current alloc region was unexpectedly found to be non-NULL"); 975 976 if (!is_humongous(word_size)) { 977 return _allocator->attempt_allocation_locked(word_size); 978 } else { 979 HeapWord* result = humongous_obj_allocate(word_size); 980 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 981 collector_state()->set_initiate_conc_mark_if_possible(true); 982 } 983 return result; 984 } 985 986 ShouldNotReachHere(); 987 } 988 989 class PostCompactionPrinterClosure: public HeapRegionClosure { 990 private: 991 G1HRPrinter* _hr_printer; 992 public: 993 bool do_heap_region(HeapRegion* hr) { 994 assert(!hr->is_young(), "not expecting to find young regions"); 995 _hr_printer->post_compaction(hr); 996 return false; 997 } 998 999 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 1000 : _hr_printer(hr_printer) { } 1001 }; 1002 1003 void G1CollectedHeap::print_hrm_post_compaction() { 1004 if (_hr_printer.is_active()) { 1005 PostCompactionPrinterClosure cl(hr_printer()); 1006 heap_region_iterate(&cl); 1007 } 1008 } 1009 1010 void G1CollectedHeap::abort_concurrent_cycle() { 1011 // If we start the compaction before the CM threads finish 1012 // scanning the root regions we might trip them over as we'll 1013 // be moving objects / updating references. So let's wait until 1014 // they are done. By telling them to abort, they should complete 1015 // early. 1016 _cm->root_regions()->abort(); 1017 _cm->root_regions()->wait_until_scan_finished(); 1018 1019 // Disable discovery and empty the discovered lists 1020 // for the CM ref processor. 1021 _ref_processor_cm->disable_discovery(); 1022 _ref_processor_cm->abandon_partial_discovery(); 1023 _ref_processor_cm->verify_no_references_recorded(); 1024 1025 // Abandon current iterations of concurrent marking and concurrent 1026 // refinement, if any are in progress. 1027 concurrent_mark()->concurrent_cycle_abort(); 1028 } 1029 1030 void G1CollectedHeap::prepare_heap_for_full_collection() { 1031 // Make sure we'll choose a new allocation region afterwards. 1032 _allocator->release_mutator_alloc_regions(); 1033 _allocator->abandon_gc_alloc_regions(); 1034 1035 // We may have added regions to the current incremental collection 1036 // set between the last GC or pause and now. We need to clear the 1037 // incremental collection set and then start rebuilding it afresh 1038 // after this full GC. 1039 abandon_collection_set(collection_set()); 1040 1041 tear_down_region_sets(false /* free_list_only */); 1042 1043 hrm()->prepare_for_full_collection_start(); 1044 } 1045 1046 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1047 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1048 assert_used_and_recalculate_used_equal(this); 1049 _verifier->verify_region_sets_optional(); 1050 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1051 _verifier->check_bitmaps("Full GC Start"); 1052 } 1053 1054 void G1CollectedHeap::prepare_heap_for_mutators() { 1055 hrm()->prepare_for_full_collection_end(); 1056 1057 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1058 ClassLoaderDataGraph::purge(); 1059 MetaspaceUtils::verify_metrics(); 1060 1061 // Prepare heap for normal collections. 1062 assert(num_free_regions() == 0, "we should not have added any free regions"); 1063 rebuild_region_sets(false /* free_list_only */); 1064 abort_refinement(); 1065 resize_heap_if_necessary(); 1066 1067 // Rebuild the strong code root lists for each region 1068 rebuild_strong_code_roots(); 1069 1070 // Purge code root memory 1071 purge_code_root_memory(); 1072 1073 // Start a new incremental collection set for the next pause 1074 start_new_collection_set(); 1075 1076 _allocator->init_mutator_alloc_regions(); 1077 1078 // Post collection state updates. 1079 MetaspaceGC::compute_new_size(); 1080 } 1081 1082 void G1CollectedHeap::abort_refinement() { 1083 if (_hot_card_cache->use_cache()) { 1084 _hot_card_cache->reset_hot_cache(); 1085 } 1086 1087 // Discard all remembered set updates. 1088 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1089 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1090 "DCQS should be empty"); 1091 } 1092 1093 void G1CollectedHeap::verify_after_full_collection() { 1094 _hrm->verify_optional(); 1095 _verifier->verify_region_sets_optional(); 1096 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1097 // Clear the previous marking bitmap, if needed for bitmap verification. 1098 // Note we cannot do this when we clear the next marking bitmap in 1099 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1100 // objects marked during a full GC against the previous bitmap. 1101 // But we need to clear it before calling check_bitmaps below since 1102 // the full GC has compacted objects and updated TAMS but not updated 1103 // the prev bitmap. 1104 if (G1VerifyBitmaps) { 1105 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1106 _cm->clear_prev_bitmap(workers()); 1107 } 1108 // This call implicitly verifies that the next bitmap is clear after Full GC. 1109 _verifier->check_bitmaps("Full GC End"); 1110 1111 // At this point there should be no regions in the 1112 // entire heap tagged as young. 1113 assert(check_young_list_empty(), "young list should be empty at this point"); 1114 1115 // Note: since we've just done a full GC, concurrent 1116 // marking is no longer active. Therefore we need not 1117 // re-enable reference discovery for the CM ref processor. 1118 // That will be done at the start of the next marking cycle. 1119 // We also know that the STW processor should no longer 1120 // discover any new references. 1121 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1122 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1123 _ref_processor_stw->verify_no_references_recorded(); 1124 _ref_processor_cm->verify_no_references_recorded(); 1125 } 1126 1127 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1128 // Post collection logging. 1129 // We should do this after we potentially resize the heap so 1130 // that all the COMMIT / UNCOMMIT events are generated before 1131 // the compaction events. 1132 print_hrm_post_compaction(); 1133 heap_transition->print(); 1134 print_heap_after_gc(); 1135 print_heap_regions(); 1136 } 1137 1138 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1139 bool clear_all_soft_refs) { 1140 assert_at_safepoint_on_vm_thread(); 1141 1142 if (GCLocker::check_active_before_gc()) { 1143 // Full GC was not completed. 1144 return false; 1145 } 1146 1147 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1148 soft_ref_policy()->should_clear_all_soft_refs(); 1149 1150 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1151 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1152 1153 collector.prepare_collection(); 1154 collector.collect(); 1155 collector.complete_collection(); 1156 1157 // Full collection was successfully completed. 1158 return true; 1159 } 1160 1161 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1162 // Currently, there is no facility in the do_full_collection(bool) API to notify 1163 // the caller that the collection did not succeed (e.g., because it was locked 1164 // out by the GC locker). So, right now, we'll ignore the return value. 1165 bool dummy = do_full_collection(true, /* explicit_gc */ 1166 clear_all_soft_refs); 1167 } 1168 1169 void G1CollectedHeap::resize_heap_if_necessary() { 1170 assert_at_safepoint_on_vm_thread(); 1171 1172 // Capacity, free and used after the GC counted as full regions to 1173 // include the waste in the following calculations. 1174 const size_t capacity_after_gc = capacity(); 1175 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1176 1177 // This is enforced in arguments.cpp. 1178 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1179 "otherwise the code below doesn't make sense"); 1180 1181 // We don't have floating point command-line arguments 1182 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1183 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1184 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1185 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1186 1187 // We have to be careful here as these two calculations can overflow 1188 // 32-bit size_t's. 1189 double used_after_gc_d = (double) used_after_gc; 1190 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1191 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1192 1193 // Let's make sure that they are both under the max heap size, which 1194 // by default will make them fit into a size_t. 1195 double desired_capacity_upper_bound = (double) MaxHeapSize; 1196 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1197 desired_capacity_upper_bound); 1198 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1199 desired_capacity_upper_bound); 1200 1201 // We can now safely turn them into size_t's. 1202 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1203 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1204 1205 // This assert only makes sense here, before we adjust them 1206 // with respect to the min and max heap size. 1207 assert(minimum_desired_capacity <= maximum_desired_capacity, 1208 "minimum_desired_capacity = " SIZE_FORMAT ", " 1209 "maximum_desired_capacity = " SIZE_FORMAT, 1210 minimum_desired_capacity, maximum_desired_capacity); 1211 1212 // Should not be greater than the heap max size. No need to adjust 1213 // it with respect to the heap min size as it's a lower bound (i.e., 1214 // we'll try to make the capacity larger than it, not smaller). 1215 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1216 // Should not be less than the heap min size. No need to adjust it 1217 // with respect to the heap max size as it's an upper bound (i.e., 1218 // we'll try to make the capacity smaller than it, not greater). 1219 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1220 1221 if (capacity_after_gc < minimum_desired_capacity) { 1222 // Don't expand unless it's significant 1223 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1224 1225 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1226 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1227 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1228 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1229 1230 expand(expand_bytes, _workers); 1231 1232 // No expansion, now see if we want to shrink 1233 } else if (capacity_after_gc > maximum_desired_capacity) { 1234 // Capacity too large, compute shrinking size 1235 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1236 1237 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1238 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1239 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1240 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1241 1242 shrink(shrink_bytes); 1243 } 1244 } 1245 1246 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1247 bool do_gc, 1248 bool clear_all_soft_refs, 1249 bool expect_null_mutator_alloc_region, 1250 bool* gc_succeeded) { 1251 *gc_succeeded = true; 1252 // Let's attempt the allocation first. 1253 HeapWord* result = 1254 attempt_allocation_at_safepoint(word_size, 1255 expect_null_mutator_alloc_region); 1256 if (result != NULL) { 1257 return result; 1258 } 1259 1260 // In a G1 heap, we're supposed to keep allocation from failing by 1261 // incremental pauses. Therefore, at least for now, we'll favor 1262 // expansion over collection. (This might change in the future if we can 1263 // do something smarter than full collection to satisfy a failed alloc.) 1264 result = expand_and_allocate(word_size); 1265 if (result != NULL) { 1266 return result; 1267 } 1268 1269 if (do_gc) { 1270 // Expansion didn't work, we'll try to do a Full GC. 1271 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1272 clear_all_soft_refs); 1273 } 1274 1275 return NULL; 1276 } 1277 1278 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1279 bool* succeeded) { 1280 assert_at_safepoint_on_vm_thread(); 1281 1282 // Attempts to allocate followed by Full GC. 1283 HeapWord* result = 1284 satisfy_failed_allocation_helper(word_size, 1285 true, /* do_gc */ 1286 false, /* clear_all_soft_refs */ 1287 false, /* expect_null_mutator_alloc_region */ 1288 succeeded); 1289 1290 if (result != NULL || !*succeeded) { 1291 return result; 1292 } 1293 1294 // Attempts to allocate followed by Full GC that will collect all soft references. 1295 result = satisfy_failed_allocation_helper(word_size, 1296 true, /* do_gc */ 1297 true, /* clear_all_soft_refs */ 1298 true, /* expect_null_mutator_alloc_region */ 1299 succeeded); 1300 1301 if (result != NULL || !*succeeded) { 1302 return result; 1303 } 1304 1305 // Attempts to allocate, no GC 1306 result = satisfy_failed_allocation_helper(word_size, 1307 false, /* do_gc */ 1308 false, /* clear_all_soft_refs */ 1309 true, /* expect_null_mutator_alloc_region */ 1310 succeeded); 1311 1312 if (result != NULL) { 1313 return result; 1314 } 1315 1316 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1317 "Flag should have been handled and cleared prior to this point"); 1318 1319 // What else? We might try synchronous finalization later. If the total 1320 // space available is large enough for the allocation, then a more 1321 // complete compaction phase than we've tried so far might be 1322 // appropriate. 1323 return NULL; 1324 } 1325 1326 // Attempting to expand the heap sufficiently 1327 // to support an allocation of the given "word_size". If 1328 // successful, perform the allocation and return the address of the 1329 // allocated block, or else "NULL". 1330 1331 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1332 assert_at_safepoint_on_vm_thread(); 1333 1334 _verifier->verify_region_sets_optional(); 1335 1336 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1337 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1338 word_size * HeapWordSize); 1339 1340 1341 if (expand(expand_bytes, _workers)) { 1342 _hrm->verify_optional(); 1343 _verifier->verify_region_sets_optional(); 1344 return attempt_allocation_at_safepoint(word_size, 1345 false /* expect_null_mutator_alloc_region */); 1346 } 1347 return NULL; 1348 } 1349 1350 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1351 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1352 aligned_expand_bytes = align_up(aligned_expand_bytes, 1353 HeapRegion::GrainBytes); 1354 1355 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1356 expand_bytes, aligned_expand_bytes); 1357 1358 if (is_maximal_no_gc()) { 1359 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1360 return false; 1361 } 1362 1363 double expand_heap_start_time_sec = os::elapsedTime(); 1364 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1365 assert(regions_to_expand > 0, "Must expand by at least one region"); 1366 1367 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1368 if (expand_time_ms != NULL) { 1369 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1370 } 1371 1372 if (expanded_by > 0) { 1373 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1374 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1375 policy()->record_new_heap_size(num_regions()); 1376 } else { 1377 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1378 1379 // The expansion of the virtual storage space was unsuccessful. 1380 // Let's see if it was because we ran out of swap. 1381 if (G1ExitOnExpansionFailure && 1382 _hrm->available() >= regions_to_expand) { 1383 // We had head room... 1384 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1385 } 1386 } 1387 return regions_to_expand > 0; 1388 } 1389 1390 bool G1CollectedHeap::expand_single_region(uint node_index) { 1391 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1392 1393 if (expanded_by == 0) { 1394 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1395 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1396 return false; 1397 } 1398 1399 policy()->record_new_heap_size(num_regions()); 1400 return true; 1401 } 1402 1403 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1404 size_t aligned_shrink_bytes = 1405 ReservedSpace::page_align_size_down(shrink_bytes); 1406 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1407 HeapRegion::GrainBytes); 1408 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1409 1410 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1411 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1412 1413 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", 1414 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1415 if (num_regions_removed > 0) { 1416 policy()->record_new_heap_size(num_regions()); 1417 } else { 1418 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1419 } 1420 } 1421 1422 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1423 _verifier->verify_region_sets_optional(); 1424 1425 // We should only reach here at the end of a Full GC or during Remark which 1426 // means we should not not be holding to any GC alloc regions. The method 1427 // below will make sure of that and do any remaining clean up. 1428 _allocator->abandon_gc_alloc_regions(); 1429 1430 // Instead of tearing down / rebuilding the free lists here, we 1431 // could instead use the remove_all_pending() method on free_list to 1432 // remove only the ones that we need to remove. 1433 tear_down_region_sets(true /* free_list_only */); 1434 shrink_helper(shrink_bytes); 1435 rebuild_region_sets(true /* free_list_only */); 1436 1437 _hrm->verify_optional(); 1438 _verifier->verify_region_sets_optional(); 1439 } 1440 1441 class OldRegionSetChecker : public HeapRegionSetChecker { 1442 public: 1443 void check_mt_safety() { 1444 // Master Old Set MT safety protocol: 1445 // (a) If we're at a safepoint, operations on the master old set 1446 // should be invoked: 1447 // - by the VM thread (which will serialize them), or 1448 // - by the GC workers while holding the FreeList_lock, if we're 1449 // at a safepoint for an evacuation pause (this lock is taken 1450 // anyway when an GC alloc region is retired so that a new one 1451 // is allocated from the free list), or 1452 // - by the GC workers while holding the OldSets_lock, if we're at a 1453 // safepoint for a cleanup pause. 1454 // (b) If we're not at a safepoint, operations on the master old set 1455 // should be invoked while holding the Heap_lock. 1456 1457 if (SafepointSynchronize::is_at_safepoint()) { 1458 guarantee(Thread::current()->is_VM_thread() || 1459 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1460 "master old set MT safety protocol at a safepoint"); 1461 } else { 1462 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1463 } 1464 } 1465 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1466 const char* get_description() { return "Old Regions"; } 1467 }; 1468 1469 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1470 public: 1471 void check_mt_safety() { 1472 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1473 "May only change archive regions during initialization or safepoint."); 1474 } 1475 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1476 const char* get_description() { return "Archive Regions"; } 1477 }; 1478 1479 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1480 public: 1481 void check_mt_safety() { 1482 // Humongous Set MT safety protocol: 1483 // (a) If we're at a safepoint, operations on the master humongous 1484 // set should be invoked by either the VM thread (which will 1485 // serialize them) or by the GC workers while holding the 1486 // OldSets_lock. 1487 // (b) If we're not at a safepoint, operations on the master 1488 // humongous set should be invoked while holding the Heap_lock. 1489 1490 if (SafepointSynchronize::is_at_safepoint()) { 1491 guarantee(Thread::current()->is_VM_thread() || 1492 OldSets_lock->owned_by_self(), 1493 "master humongous set MT safety protocol at a safepoint"); 1494 } else { 1495 guarantee(Heap_lock->owned_by_self(), 1496 "master humongous set MT safety protocol outside a safepoint"); 1497 } 1498 } 1499 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1500 const char* get_description() { return "Humongous Regions"; } 1501 }; 1502 1503 G1CollectedHeap::G1CollectedHeap() : 1504 CollectedHeap(), 1505 _young_gen_sampling_thread(NULL), 1506 _workers(NULL), 1507 _card_table(NULL), 1508 _soft_ref_policy(), 1509 _old_set("Old Region Set", new OldRegionSetChecker()), 1510 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1511 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1512 _bot(NULL), 1513 _listener(), 1514 _numa(G1NUMA::create()), 1515 _hrm(NULL), 1516 _allocator(NULL), 1517 _verifier(NULL), 1518 _summary_bytes_used(0), 1519 _bytes_used_during_gc(0), 1520 _archive_allocator(NULL), 1521 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1522 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1523 _expand_heap_after_alloc_failure(true), 1524 _g1mm(NULL), 1525 _humongous_reclaim_candidates(), 1526 _has_humongous_reclaim_candidates(false), 1527 _hr_printer(), 1528 _collector_state(), 1529 _old_marking_cycles_started(0), 1530 _old_marking_cycles_completed(0), 1531 _eden(), 1532 _survivor(), 1533 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1534 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1535 _policy(G1Policy::create_policy(_gc_timer_stw)), 1536 _heap_sizing_policy(NULL), 1537 _collection_set(this, _policy), 1538 _hot_card_cache(NULL), 1539 _rem_set(NULL), 1540 _cm(NULL), 1541 _cm_thread(NULL), 1542 _cr(NULL), 1543 _task_queues(NULL), 1544 _evacuation_failed(false), 1545 _evacuation_failed_info_array(NULL), 1546 _preserved_marks_set(true /* in_c_heap */), 1547 #ifndef PRODUCT 1548 _evacuation_failure_alot_for_current_gc(false), 1549 _evacuation_failure_alot_gc_number(0), 1550 _evacuation_failure_alot_count(0), 1551 #endif 1552 _ref_processor_stw(NULL), 1553 _is_alive_closure_stw(this), 1554 _is_subject_to_discovery_stw(this), 1555 _ref_processor_cm(NULL), 1556 _is_alive_closure_cm(this), 1557 _is_subject_to_discovery_cm(this), 1558 _region_attr() { 1559 1560 _verifier = new G1HeapVerifier(this); 1561 1562 _allocator = new G1Allocator(this); 1563 1564 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1565 1566 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1567 1568 // Override the default _filler_array_max_size so that no humongous filler 1569 // objects are created. 1570 _filler_array_max_size = _humongous_object_threshold_in_words; 1571 1572 uint n_queues = ParallelGCThreads; 1573 _task_queues = new RefToScanQueueSet(n_queues); 1574 1575 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1576 1577 for (uint i = 0; i < n_queues; i++) { 1578 RefToScanQueue* q = new RefToScanQueue(); 1579 q->initialize(); 1580 _task_queues->register_queue(i, q); 1581 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1582 } 1583 1584 // Initialize the G1EvacuationFailureALot counters and flags. 1585 NOT_PRODUCT(reset_evacuation_should_fail();) 1586 _gc_tracer_stw->initialize(); 1587 1588 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1589 } 1590 1591 static size_t actual_reserved_page_size(ReservedSpace rs) { 1592 size_t page_size = os::vm_page_size(); 1593 if (UseLargePages) { 1594 // There are two ways to manage large page memory. 1595 // 1. OS supports committing large page memory. 1596 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1597 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1598 // we reserved memory without large page. 1599 if (os::can_commit_large_page_memory() || rs.special()) { 1600 // An alignment at ReservedSpace comes from preferred page size or 1601 // heap alignment, and if the alignment came from heap alignment, it could be 1602 // larger than large pages size. So need to cap with the large page size. 1603 page_size = MIN2(rs.alignment(), os::large_page_size()); 1604 } 1605 } 1606 1607 return page_size; 1608 } 1609 1610 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1611 size_t size, 1612 size_t translation_factor) { 1613 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1614 // Allocate a new reserved space, preferring to use large pages. 1615 ReservedSpace rs(size, preferred_page_size); 1616 size_t page_size = actual_reserved_page_size(rs); 1617 G1RegionToSpaceMapper* result = 1618 G1RegionToSpaceMapper::create_mapper(rs, 1619 size, 1620 page_size, 1621 HeapRegion::GrainBytes, 1622 translation_factor, 1623 mtGC); 1624 1625 os::trace_page_sizes_for_requested_size(description, 1626 size, 1627 preferred_page_size, 1628 page_size, 1629 rs.base(), 1630 rs.size()); 1631 1632 return result; 1633 } 1634 1635 jint G1CollectedHeap::initialize_concurrent_refinement() { 1636 jint ecode = JNI_OK; 1637 _cr = G1ConcurrentRefine::create(&ecode); 1638 return ecode; 1639 } 1640 1641 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1642 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1643 if (_young_gen_sampling_thread->osthread() == NULL) { 1644 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1645 return JNI_ENOMEM; 1646 } 1647 return JNI_OK; 1648 } 1649 1650 jint G1CollectedHeap::initialize() { 1651 1652 // Necessary to satisfy locking discipline assertions. 1653 1654 MutexLocker x(Heap_lock); 1655 1656 // While there are no constraints in the GC code that HeapWordSize 1657 // be any particular value, there are multiple other areas in the 1658 // system which believe this to be true (e.g. oop->object_size in some 1659 // cases incorrectly returns the size in wordSize units rather than 1660 // HeapWordSize). 1661 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1662 1663 size_t init_byte_size = InitialHeapSize; 1664 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1665 1666 // Ensure that the sizes are properly aligned. 1667 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1668 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1669 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1670 1671 // Reserve the maximum. 1672 1673 // When compressed oops are enabled, the preferred heap base 1674 // is calculated by subtracting the requested size from the 1675 // 32Gb boundary and using the result as the base address for 1676 // heap reservation. If the requested size is not aligned to 1677 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1678 // into the ReservedHeapSpace constructor) then the actual 1679 // base of the reserved heap may end up differing from the 1680 // address that was requested (i.e. the preferred heap base). 1681 // If this happens then we could end up using a non-optimal 1682 // compressed oops mode. 1683 1684 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1685 HeapAlignment); 1686 1687 initialize_reserved_region(heap_rs); 1688 1689 // Create the barrier set for the entire reserved region. 1690 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1691 ct->initialize(); 1692 G1BarrierSet* bs = new G1BarrierSet(ct); 1693 bs->initialize(); 1694 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1695 BarrierSet::set_barrier_set(bs); 1696 _card_table = ct; 1697 1698 { 1699 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1700 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1701 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1702 } 1703 1704 // Create the hot card cache. 1705 _hot_card_cache = new G1HotCardCache(this); 1706 1707 // Carve out the G1 part of the heap. 1708 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1709 size_t page_size = actual_reserved_page_size(heap_rs); 1710 G1RegionToSpaceMapper* heap_storage = 1711 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1712 g1_rs.size(), 1713 page_size, 1714 HeapRegion::GrainBytes, 1715 1, 1716 mtJavaHeap); 1717 if(heap_storage == NULL) { 1718 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1719 return JNI_ERR; 1720 } 1721 1722 os::trace_page_sizes("Heap", 1723 MinHeapSize, 1724 reserved_byte_size, 1725 page_size, 1726 heap_rs.base(), 1727 heap_rs.size()); 1728 heap_storage->set_mapping_changed_listener(&_listener); 1729 1730 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1731 G1RegionToSpaceMapper* bot_storage = 1732 create_aux_memory_mapper("Block Offset Table", 1733 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1734 G1BlockOffsetTable::heap_map_factor()); 1735 1736 G1RegionToSpaceMapper* cardtable_storage = 1737 create_aux_memory_mapper("Card Table", 1738 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1739 G1CardTable::heap_map_factor()); 1740 1741 G1RegionToSpaceMapper* card_counts_storage = 1742 create_aux_memory_mapper("Card Counts Table", 1743 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1744 G1CardCounts::heap_map_factor()); 1745 1746 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1747 G1RegionToSpaceMapper* prev_bitmap_storage = 1748 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1749 G1RegionToSpaceMapper* next_bitmap_storage = 1750 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1751 1752 _hrm = HeapRegionManager::create_manager(this); 1753 1754 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1755 _card_table->initialize(cardtable_storage); 1756 1757 // Do later initialization work for concurrent refinement. 1758 _hot_card_cache->initialize(card_counts_storage); 1759 1760 // 6843694 - ensure that the maximum region index can fit 1761 // in the remembered set structures. 1762 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1763 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1764 1765 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1766 // start within the first card. 1767 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1768 // Also create a G1 rem set. 1769 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1770 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1771 1772 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1773 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1774 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1775 "too many cards per region"); 1776 1777 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1778 1779 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1780 1781 { 1782 HeapWord* start = _hrm->reserved().start(); 1783 HeapWord* end = _hrm->reserved().end(); 1784 size_t granularity = HeapRegion::GrainBytes; 1785 1786 _region_attr.initialize(start, end, granularity); 1787 _humongous_reclaim_candidates.initialize(start, end, granularity); 1788 } 1789 1790 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1791 true /* are_GC_task_threads */, 1792 false /* are_ConcurrentGC_threads */); 1793 if (_workers == NULL) { 1794 return JNI_ENOMEM; 1795 } 1796 _workers->initialize_workers(); 1797 1798 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1799 1800 // Create the G1ConcurrentMark data structure and thread. 1801 // (Must do this late, so that "max_regions" is defined.) 1802 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1803 if (!_cm->completed_initialization()) { 1804 vm_shutdown_during_initialization("Could not initialize G1ConcurrentMark"); 1805 return JNI_ENOMEM; 1806 } 1807 _cm_thread = _cm->cm_thread(); 1808 1809 // Now expand into the initial heap size. 1810 if (!expand(init_byte_size, _workers)) { 1811 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1812 return JNI_ENOMEM; 1813 } 1814 1815 // Perform any initialization actions delegated to the policy. 1816 policy()->init(this, &_collection_set); 1817 1818 jint ecode = initialize_concurrent_refinement(); 1819 if (ecode != JNI_OK) { 1820 return ecode; 1821 } 1822 1823 ecode = initialize_young_gen_sampling_thread(); 1824 if (ecode != JNI_OK) { 1825 return ecode; 1826 } 1827 1828 { 1829 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1830 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1831 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1832 } 1833 1834 // Here we allocate the dummy HeapRegion that is required by the 1835 // G1AllocRegion class. 1836 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1837 1838 // We'll re-use the same region whether the alloc region will 1839 // require BOT updates or not and, if it doesn't, then a non-young 1840 // region will complain that it cannot support allocations without 1841 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1842 dummy_region->set_eden(); 1843 // Make sure it's full. 1844 dummy_region->set_top(dummy_region->end()); 1845 G1AllocRegion::setup(this, dummy_region); 1846 1847 _allocator->init_mutator_alloc_regions(); 1848 1849 // Do create of the monitoring and management support so that 1850 // values in the heap have been properly initialized. 1851 _g1mm = new G1MonitoringSupport(this); 1852 1853 G1StringDedup::initialize(); 1854 1855 _preserved_marks_set.init(ParallelGCThreads); 1856 1857 _collection_set.initialize(max_regions()); 1858 1859 return JNI_OK; 1860 } 1861 1862 void G1CollectedHeap::stop() { 1863 // Stop all concurrent threads. We do this to make sure these threads 1864 // do not continue to execute and access resources (e.g. logging) 1865 // that are destroyed during shutdown. 1866 _cr->stop(); 1867 _young_gen_sampling_thread->stop(); 1868 _cm_thread->stop(); 1869 if (G1StringDedup::is_enabled()) { 1870 G1StringDedup::stop(); 1871 } 1872 } 1873 1874 void G1CollectedHeap::safepoint_synchronize_begin() { 1875 SuspendibleThreadSet::synchronize(); 1876 } 1877 1878 void G1CollectedHeap::safepoint_synchronize_end() { 1879 SuspendibleThreadSet::desynchronize(); 1880 } 1881 1882 void G1CollectedHeap::post_initialize() { 1883 CollectedHeap::post_initialize(); 1884 ref_processing_init(); 1885 } 1886 1887 void G1CollectedHeap::ref_processing_init() { 1888 // Reference processing in G1 currently works as follows: 1889 // 1890 // * There are two reference processor instances. One is 1891 // used to record and process discovered references 1892 // during concurrent marking; the other is used to 1893 // record and process references during STW pauses 1894 // (both full and incremental). 1895 // * Both ref processors need to 'span' the entire heap as 1896 // the regions in the collection set may be dotted around. 1897 // 1898 // * For the concurrent marking ref processor: 1899 // * Reference discovery is enabled at initial marking. 1900 // * Reference discovery is disabled and the discovered 1901 // references processed etc during remarking. 1902 // * Reference discovery is MT (see below). 1903 // * Reference discovery requires a barrier (see below). 1904 // * Reference processing may or may not be MT 1905 // (depending on the value of ParallelRefProcEnabled 1906 // and ParallelGCThreads). 1907 // * A full GC disables reference discovery by the CM 1908 // ref processor and abandons any entries on it's 1909 // discovered lists. 1910 // 1911 // * For the STW processor: 1912 // * Non MT discovery is enabled at the start of a full GC. 1913 // * Processing and enqueueing during a full GC is non-MT. 1914 // * During a full GC, references are processed after marking. 1915 // 1916 // * Discovery (may or may not be MT) is enabled at the start 1917 // of an incremental evacuation pause. 1918 // * References are processed near the end of a STW evacuation pause. 1919 // * For both types of GC: 1920 // * Discovery is atomic - i.e. not concurrent. 1921 // * Reference discovery will not need a barrier. 1922 1923 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1924 1925 // Concurrent Mark ref processor 1926 _ref_processor_cm = 1927 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1928 mt_processing, // mt processing 1929 ParallelGCThreads, // degree of mt processing 1930 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1931 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1932 false, // Reference discovery is not atomic 1933 &_is_alive_closure_cm, // is alive closure 1934 true); // allow changes to number of processing threads 1935 1936 // STW ref processor 1937 _ref_processor_stw = 1938 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1939 mt_processing, // mt processing 1940 ParallelGCThreads, // degree of mt processing 1941 (ParallelGCThreads > 1), // mt discovery 1942 ParallelGCThreads, // degree of mt discovery 1943 true, // Reference discovery is atomic 1944 &_is_alive_closure_stw, // is alive closure 1945 true); // allow changes to number of processing threads 1946 } 1947 1948 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1949 return &_soft_ref_policy; 1950 } 1951 1952 size_t G1CollectedHeap::capacity() const { 1953 return _hrm->length() * HeapRegion::GrainBytes; 1954 } 1955 1956 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1957 return _hrm->total_free_bytes(); 1958 } 1959 1960 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1961 _hot_card_cache->drain(cl, worker_id); 1962 } 1963 1964 // Computes the sum of the storage used by the various regions. 1965 size_t G1CollectedHeap::used() const { 1966 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1967 if (_archive_allocator != NULL) { 1968 result += _archive_allocator->used(); 1969 } 1970 return result; 1971 } 1972 1973 size_t G1CollectedHeap::used_unlocked() const { 1974 return _summary_bytes_used; 1975 } 1976 1977 class SumUsedClosure: public HeapRegionClosure { 1978 size_t _used; 1979 public: 1980 SumUsedClosure() : _used(0) {} 1981 bool do_heap_region(HeapRegion* r) { 1982 _used += r->used(); 1983 return false; 1984 } 1985 size_t result() { return _used; } 1986 }; 1987 1988 size_t G1CollectedHeap::recalculate_used() const { 1989 SumUsedClosure blk; 1990 heap_region_iterate(&blk); 1991 return blk.result(); 1992 } 1993 1994 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1995 switch (cause) { 1996 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1997 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1998 case GCCause::_wb_conc_mark: return true; 1999 default : return false; 2000 } 2001 } 2002 2003 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2004 switch (cause) { 2005 case GCCause::_g1_humongous_allocation: return true; 2006 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2007 case GCCause::_wb_breakpoint: return true; 2008 default: return is_user_requested_concurrent_full_gc(cause); 2009 } 2010 } 2011 2012 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2013 if (policy()->force_upgrade_to_full()) { 2014 return true; 2015 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2016 return false; 2017 } else if (has_regions_left_for_allocation()) { 2018 return false; 2019 } else { 2020 return true; 2021 } 2022 } 2023 2024 #ifndef PRODUCT 2025 void G1CollectedHeap::allocate_dummy_regions() { 2026 // Let's fill up most of the region 2027 size_t word_size = HeapRegion::GrainWords - 1024; 2028 // And as a result the region we'll allocate will be humongous. 2029 guarantee(is_humongous(word_size), "sanity"); 2030 2031 // _filler_array_max_size is set to humongous object threshold 2032 // but temporarily change it to use CollectedHeap::fill_with_object(). 2033 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2034 2035 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2036 // Let's use the existing mechanism for the allocation 2037 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2038 if (dummy_obj != NULL) { 2039 MemRegion mr(dummy_obj, word_size); 2040 CollectedHeap::fill_with_object(mr); 2041 } else { 2042 // If we can't allocate once, we probably cannot allocate 2043 // again. Let's get out of the loop. 2044 break; 2045 } 2046 } 2047 } 2048 #endif // !PRODUCT 2049 2050 void G1CollectedHeap::increment_old_marking_cycles_started() { 2051 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2052 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2053 "Wrong marking cycle count (started: %d, completed: %d)", 2054 _old_marking_cycles_started, _old_marking_cycles_completed); 2055 2056 _old_marking_cycles_started++; 2057 } 2058 2059 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2060 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 2061 2062 // We assume that if concurrent == true, then the caller is a 2063 // concurrent thread that was joined the Suspendible Thread 2064 // Set. If there's ever a cheap way to check this, we should add an 2065 // assert here. 2066 2067 // Given that this method is called at the end of a Full GC or of a 2068 // concurrent cycle, and those can be nested (i.e., a Full GC can 2069 // interrupt a concurrent cycle), the number of full collections 2070 // completed should be either one (in the case where there was no 2071 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2072 // behind the number of full collections started. 2073 2074 // This is the case for the inner caller, i.e. a Full GC. 2075 assert(concurrent || 2076 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2077 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2078 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2079 "is inconsistent with _old_marking_cycles_completed = %u", 2080 _old_marking_cycles_started, _old_marking_cycles_completed); 2081 2082 // This is the case for the outer caller, i.e. the concurrent cycle. 2083 assert(!concurrent || 2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2085 "for outer caller (concurrent cycle): " 2086 "_old_marking_cycles_started = %u " 2087 "is inconsistent with _old_marking_cycles_completed = %u", 2088 _old_marking_cycles_started, _old_marking_cycles_completed); 2089 2090 _old_marking_cycles_completed += 1; 2091 2092 // We need to clear the "in_progress" flag in the CM thread before 2093 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2094 // is set) so that if a waiter requests another System.gc() it doesn't 2095 // incorrectly see that a marking cycle is still in progress. 2096 if (concurrent) { 2097 _cm_thread->set_idle(); 2098 } 2099 2100 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 2101 // for a full GC to finish that their wait is over. 2102 ml.notify_all(); 2103 } 2104 2105 void G1CollectedHeap::collect(GCCause::Cause cause) { 2106 try_collect(cause); 2107 } 2108 2109 // Return true if (x < y) with allowance for wraparound. 2110 static bool gc_counter_less_than(uint x, uint y) { 2111 return (x - y) > (UINT_MAX/2); 2112 } 2113 2114 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 2115 // Macro so msg printing is format-checked. 2116 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 2117 do { \ 2118 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 2119 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 2120 ResourceMark rm; /* For thread name. */ \ 2121 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 2122 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 2123 Thread::current()->name(), \ 2124 GCCause::to_string(cause)); \ 2125 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 2126 } \ 2127 } while (0) 2128 2129 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 2130 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 2131 2132 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 2133 uint gc_counter, 2134 uint old_marking_started_before) { 2135 assert_heap_not_locked(); 2136 assert(should_do_concurrent_full_gc(cause), 2137 "Non-concurrent cause %s", GCCause::to_string(cause)); 2138 2139 for (uint i = 1; true; ++i) { 2140 // Try to schedule an initial-mark evacuation pause that will 2141 // start a concurrent cycle. 2142 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 2143 VM_G1TryInitiateConcMark op(gc_counter, 2144 cause, 2145 policy()->max_pause_time_ms()); 2146 VMThread::execute(&op); 2147 2148 // Request is trivially finished. 2149 if (cause == GCCause::_g1_periodic_collection) { 2150 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 2151 return op.gc_succeeded(); 2152 } 2153 2154 // If VMOp skipped initiating concurrent marking cycle because 2155 // we're terminating, then we're done. 2156 if (op.terminating()) { 2157 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 2158 return false; 2159 } 2160 2161 // Lock to get consistent set of values. 2162 uint old_marking_started_after; 2163 uint old_marking_completed_after; 2164 { 2165 MutexLocker ml(Heap_lock); 2166 // Update gc_counter for retrying VMOp if needed. Captured here to be 2167 // consistent with the values we use below for termination tests. If 2168 // a retry is needed after a possible wait, and another collection 2169 // occurs in the meantime, it will cause our retry to be skipped and 2170 // we'll recheck for termination with updated conditions from that 2171 // more recent collection. That's what we want, rather than having 2172 // our retry possibly perform an unnecessary collection. 2173 gc_counter = total_collections(); 2174 old_marking_started_after = _old_marking_cycles_started; 2175 old_marking_completed_after = _old_marking_cycles_completed; 2176 } 2177 2178 if (cause == GCCause::_wb_breakpoint) { 2179 if (op.gc_succeeded()) { 2180 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2181 return true; 2182 } 2183 // When _wb_breakpoint there can't be another cycle or deferred. 2184 assert(!op.cycle_already_in_progress(), "invariant"); 2185 assert(!op.whitebox_attached(), "invariant"); 2186 // Concurrent cycle attempt might have been cancelled by some other 2187 // collection, so retry. Unlike other cases below, we want to retry 2188 // even if cancelled by a STW full collection, because we really want 2189 // to start a concurrent cycle. 2190 if (old_marking_started_before != old_marking_started_after) { 2191 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 2192 old_marking_started_before = old_marking_started_after; 2193 } 2194 } else if (!GCCause::is_user_requested_gc(cause)) { 2195 // For an "automatic" (not user-requested) collection, we just need to 2196 // ensure that progress is made. 2197 // 2198 // Request is finished if any of 2199 // (1) the VMOp successfully performed a GC, 2200 // (2) a concurrent cycle was already in progress, 2201 // (3) whitebox is controlling concurrent cycles, 2202 // (4) a new cycle was started (by this thread or some other), or 2203 // (5) a Full GC was performed. 2204 // Cases (4) and (5) are detected together by a change to 2205 // _old_marking_cycles_started. 2206 // 2207 // Note that (1) does not imply (4). If we're still in the mixed 2208 // phase of an earlier concurrent collection, the request to make the 2209 // collection an initial-mark won't be honored. If we don't check for 2210 // both conditions we'll spin doing back-to-back collections. 2211 if (op.gc_succeeded() || 2212 op.cycle_already_in_progress() || 2213 op.whitebox_attached() || 2214 (old_marking_started_before != old_marking_started_after)) { 2215 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2216 return true; 2217 } 2218 } else { // User-requested GC. 2219 // For a user-requested collection, we want to ensure that a complete 2220 // full collection has been performed before returning, but without 2221 // waiting for more than needed. 2222 2223 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 2224 // new cycle was started. That's good, because it's not clear what we 2225 // should do otherwise. Trying again just does back to back GCs. 2226 // Can't wait for someone else to start a cycle. And returning fails 2227 // to meet the goal of ensuring a full collection was performed. 2228 assert(!op.gc_succeeded() || 2229 (old_marking_started_before != old_marking_started_after), 2230 "invariant: succeeded %s, started before %u, started after %u", 2231 BOOL_TO_STR(op.gc_succeeded()), 2232 old_marking_started_before, old_marking_started_after); 2233 2234 // Request is finished if a full collection (concurrent or stw) 2235 // was started after this request and has completed, e.g. 2236 // started_before < completed_after. 2237 if (gc_counter_less_than(old_marking_started_before, 2238 old_marking_completed_after)) { 2239 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2240 return true; 2241 } 2242 2243 if (old_marking_started_after != old_marking_completed_after) { 2244 // If there is an in-progress cycle (possibly started by us), then 2245 // wait for that cycle to complete, e.g. 2246 // while completed_now < started_after. 2247 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2248 MonitorLocker ml(G1OldGCCount_lock); 2249 while (gc_counter_less_than(_old_marking_cycles_completed, 2250 old_marking_started_after)) { 2251 ml.wait(); 2252 } 2253 // Request is finished if the collection we just waited for was 2254 // started after this request. 2255 if (old_marking_started_before != old_marking_started_after) { 2256 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2257 return true; 2258 } 2259 } 2260 2261 // If VMOp was successful then it started a new cycle that the above 2262 // wait &etc should have recognized as finishing this request. This 2263 // differs from a non-user-request, where gc_succeeded does not imply 2264 // a new cycle was started. 2265 assert(!op.gc_succeeded(), "invariant"); 2266 2267 if (op.cycle_already_in_progress()) { 2268 // If VMOp failed because a cycle was already in progress, it 2269 // is now complete. But it didn't finish this user-requested 2270 // GC, so try again. 2271 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2272 continue; 2273 } else if (op.whitebox_attached()) { 2274 // If WhiteBox wants control, wait for notification of a state 2275 // change in the controller, then try again. Don't wait for 2276 // release of control, since collections may complete while in 2277 // control. Note: This won't recognize a STW full collection 2278 // while waiting; we can't wait on multiple monitors. 2279 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 2280 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 2281 if (ConcurrentGCBreakpoints::is_controlled()) { 2282 ml.wait(); 2283 } 2284 continue; 2285 } 2286 } 2287 2288 // Collection failed and should be retried. 2289 assert(op.transient_failure(), "invariant"); 2290 2291 if (GCLocker::is_active_and_needs_gc()) { 2292 // If GCLocker is active, wait until clear before retrying. 2293 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2294 GCLocker::stall_until_clear(); 2295 } 2296 2297 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2298 } 2299 } 2300 2301 bool G1CollectedHeap::try_collect(GCCause::Cause cause) { 2302 assert_heap_not_locked(); 2303 2304 // Lock to get consistent set of values. 2305 uint gc_count_before; 2306 uint full_gc_count_before; 2307 uint old_marking_started_before; 2308 { 2309 MutexLocker ml(Heap_lock); 2310 gc_count_before = total_collections(); 2311 full_gc_count_before = total_full_collections(); 2312 old_marking_started_before = _old_marking_cycles_started; 2313 } 2314 2315 if (should_do_concurrent_full_gc(cause)) { 2316 return try_collect_concurrently(cause, 2317 gc_count_before, 2318 old_marking_started_before); 2319 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2320 // Indicate failure to be consistent with VMOp failure due to 2321 // another collection slipping in after our gc_count but before 2322 // our request is processed. 2323 return false; 2324 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2325 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2326 2327 // Schedule a standard evacuation pause. We're setting word_size 2328 // to 0 which means that we are not requesting a post-GC allocation. 2329 VM_G1CollectForAllocation op(0, /* word_size */ 2330 gc_count_before, 2331 cause, 2332 policy()->max_pause_time_ms()); 2333 VMThread::execute(&op); 2334 return op.gc_succeeded(); 2335 } else { 2336 // Schedule a Full GC. 2337 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2338 VMThread::execute(&op); 2339 return op.gc_succeeded(); 2340 } 2341 } 2342 2343 bool G1CollectedHeap::is_in(const void* p) const { 2344 if (_hrm->reserved().contains(p)) { 2345 // Given that we know that p is in the reserved space, 2346 // heap_region_containing() should successfully 2347 // return the containing region. 2348 HeapRegion* hr = heap_region_containing(p); 2349 return hr->is_in(p); 2350 } else { 2351 return false; 2352 } 2353 } 2354 2355 #ifdef ASSERT 2356 bool G1CollectedHeap::is_in_exact(const void* p) const { 2357 bool contains = reserved_region().contains(p); 2358 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2359 if (contains && available) { 2360 return true; 2361 } else { 2362 return false; 2363 } 2364 } 2365 #endif 2366 2367 // Iteration functions. 2368 2369 // Iterates an ObjectClosure over all objects within a HeapRegion. 2370 2371 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2372 ObjectClosure* _cl; 2373 public: 2374 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2375 bool do_heap_region(HeapRegion* r) { 2376 if (!r->is_continues_humongous()) { 2377 r->object_iterate(_cl); 2378 } 2379 return false; 2380 } 2381 }; 2382 2383 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2384 IterateObjectClosureRegionClosure blk(cl); 2385 heap_region_iterate(&blk); 2386 } 2387 2388 void G1CollectedHeap::keep_alive(oop obj) { 2389 G1BarrierSet::enqueue(obj); 2390 } 2391 2392 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2393 _hrm->iterate(cl); 2394 } 2395 2396 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2397 HeapRegionClaimer *hrclaimer, 2398 uint worker_id) const { 2399 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2400 } 2401 2402 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2403 HeapRegionClaimer *hrclaimer) const { 2404 _hrm->par_iterate(cl, hrclaimer, 0); 2405 } 2406 2407 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2408 _collection_set.iterate(cl); 2409 } 2410 2411 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2412 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers()); 2413 } 2414 2415 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2416 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2417 } 2418 2419 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2420 HeapRegion* hr = heap_region_containing(addr); 2421 return hr->block_start(addr); 2422 } 2423 2424 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2425 HeapRegion* hr = heap_region_containing(addr); 2426 return hr->block_is_obj(addr); 2427 } 2428 2429 bool G1CollectedHeap::supports_tlab_allocation() const { 2430 return true; 2431 } 2432 2433 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2434 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2435 } 2436 2437 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2438 return _eden.length() * HeapRegion::GrainBytes; 2439 } 2440 2441 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2442 // must be equal to the humongous object limit. 2443 size_t G1CollectedHeap::max_tlab_size() const { 2444 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2445 } 2446 2447 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2448 return _allocator->unsafe_max_tlab_alloc(); 2449 } 2450 2451 size_t G1CollectedHeap::max_capacity() const { 2452 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2453 } 2454 2455 size_t G1CollectedHeap::max_reserved_capacity() const { 2456 return _hrm->max_length() * HeapRegion::GrainBytes; 2457 } 2458 2459 jlong G1CollectedHeap::millis_since_last_gc() { 2460 // See the notes in GenCollectedHeap::millis_since_last_gc() 2461 // for more information about the implementation. 2462 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2463 _policy->collection_pause_end_millis(); 2464 if (ret_val < 0) { 2465 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2466 ". returning zero instead.", ret_val); 2467 return 0; 2468 } 2469 return ret_val; 2470 } 2471 2472 void G1CollectedHeap::deduplicate_string(oop str) { 2473 assert(java_lang_String::is_instance(str), "invariant"); 2474 2475 if (G1StringDedup::is_enabled()) { 2476 G1StringDedup::deduplicate(str); 2477 } 2478 } 2479 2480 void G1CollectedHeap::prepare_for_verify() { 2481 _verifier->prepare_for_verify(); 2482 } 2483 2484 void G1CollectedHeap::verify(VerifyOption vo) { 2485 _verifier->verify(vo); 2486 } 2487 2488 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2489 return true; 2490 } 2491 2492 bool G1CollectedHeap::is_heterogeneous_heap() const { 2493 return G1Arguments::is_heterogeneous_heap(); 2494 } 2495 2496 class PrintRegionClosure: public HeapRegionClosure { 2497 outputStream* _st; 2498 public: 2499 PrintRegionClosure(outputStream* st) : _st(st) {} 2500 bool do_heap_region(HeapRegion* r) { 2501 r->print_on(_st); 2502 return false; 2503 } 2504 }; 2505 2506 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2507 const HeapRegion* hr, 2508 const VerifyOption vo) const { 2509 switch (vo) { 2510 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2511 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2512 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2513 default: ShouldNotReachHere(); 2514 } 2515 return false; // keep some compilers happy 2516 } 2517 2518 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2519 const VerifyOption vo) const { 2520 switch (vo) { 2521 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2522 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2523 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2524 default: ShouldNotReachHere(); 2525 } 2526 return false; // keep some compilers happy 2527 } 2528 2529 void G1CollectedHeap::print_heap_regions() const { 2530 LogTarget(Trace, gc, heap, region) lt; 2531 if (lt.is_enabled()) { 2532 LogStream ls(lt); 2533 print_regions_on(&ls); 2534 } 2535 } 2536 2537 void G1CollectedHeap::print_on(outputStream* st) const { 2538 st->print(" %-20s", "garbage-first heap"); 2539 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2540 capacity()/K, used_unlocked()/K); 2541 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2542 p2i(_hrm->reserved().start()), 2543 p2i(_hrm->reserved().end())); 2544 st->cr(); 2545 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2546 uint young_regions = young_regions_count(); 2547 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2548 (size_t) young_regions * HeapRegion::GrainBytes / K); 2549 uint survivor_regions = survivor_regions_count(); 2550 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2551 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2552 st->cr(); 2553 if (_numa->is_enabled()) { 2554 uint num_nodes = _numa->num_active_nodes(); 2555 st->print(" remaining free region(s) on each NUMA node: "); 2556 const int* node_ids = _numa->node_ids(); 2557 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2558 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index)); 2559 } 2560 st->cr(); 2561 } 2562 MetaspaceUtils::print_on(st); 2563 } 2564 2565 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2566 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2567 "HS=humongous(starts), HC=humongous(continues), " 2568 "CS=collection set, F=free, " 2569 "OA=open archive, CA=closed archive, " 2570 "TAMS=top-at-mark-start (previous, next)"); 2571 PrintRegionClosure blk(st); 2572 heap_region_iterate(&blk); 2573 } 2574 2575 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2576 print_on(st); 2577 2578 // Print the per-region information. 2579 print_regions_on(st); 2580 } 2581 2582 void G1CollectedHeap::print_on_error(outputStream* st) const { 2583 this->CollectedHeap::print_on_error(st); 2584 2585 if (_cm != NULL) { 2586 st->cr(); 2587 _cm->print_on_error(st); 2588 } 2589 } 2590 2591 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2592 workers()->print_worker_threads_on(st); 2593 _cm_thread->print_on(st); 2594 st->cr(); 2595 _cm->print_worker_threads_on(st); 2596 _cr->print_threads_on(st); 2597 _young_gen_sampling_thread->print_on(st); 2598 if (G1StringDedup::is_enabled()) { 2599 G1StringDedup::print_worker_threads_on(st); 2600 } 2601 } 2602 2603 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2604 workers()->threads_do(tc); 2605 tc->do_thread(_cm_thread); 2606 _cm->threads_do(tc); 2607 _cr->threads_do(tc); 2608 tc->do_thread(_young_gen_sampling_thread); 2609 if (G1StringDedup::is_enabled()) { 2610 G1StringDedup::threads_do(tc); 2611 } 2612 } 2613 2614 void G1CollectedHeap::print_tracing_info() const { 2615 rem_set()->print_summary_info(); 2616 concurrent_mark()->print_summary_info(); 2617 } 2618 2619 #ifndef PRODUCT 2620 // Helpful for debugging RSet issues. 2621 2622 class PrintRSetsClosure : public HeapRegionClosure { 2623 private: 2624 const char* _msg; 2625 size_t _occupied_sum; 2626 2627 public: 2628 bool do_heap_region(HeapRegion* r) { 2629 HeapRegionRemSet* hrrs = r->rem_set(); 2630 size_t occupied = hrrs->occupied(); 2631 _occupied_sum += occupied; 2632 2633 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2634 if (occupied == 0) { 2635 tty->print_cr(" RSet is empty"); 2636 } else { 2637 hrrs->print(); 2638 } 2639 tty->print_cr("----------"); 2640 return false; 2641 } 2642 2643 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2644 tty->cr(); 2645 tty->print_cr("========================================"); 2646 tty->print_cr("%s", msg); 2647 tty->cr(); 2648 } 2649 2650 ~PrintRSetsClosure() { 2651 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2652 tty->print_cr("========================================"); 2653 tty->cr(); 2654 } 2655 }; 2656 2657 void G1CollectedHeap::print_cset_rsets() { 2658 PrintRSetsClosure cl("Printing CSet RSets"); 2659 collection_set_iterate_all(&cl); 2660 } 2661 2662 void G1CollectedHeap::print_all_rsets() { 2663 PrintRSetsClosure cl("Printing All RSets");; 2664 heap_region_iterate(&cl); 2665 } 2666 #endif // PRODUCT 2667 2668 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2669 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2670 } 2671 2672 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2673 2674 size_t eden_used_bytes = _eden.used_bytes(); 2675 size_t survivor_used_bytes = _survivor.used_bytes(); 2676 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2677 2678 size_t eden_capacity_bytes = 2679 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2680 2681 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2682 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2683 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2684 } 2685 2686 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2687 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2688 stats->unused(), stats->used(), stats->region_end_waste(), 2689 stats->regions_filled(), stats->direct_allocated(), 2690 stats->failure_used(), stats->failure_waste()); 2691 } 2692 2693 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2694 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2695 gc_tracer->report_gc_heap_summary(when, heap_summary); 2696 2697 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2698 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2699 } 2700 2701 G1CollectedHeap* G1CollectedHeap::heap() { 2702 CollectedHeap* heap = Universe::heap(); 2703 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2704 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2705 return (G1CollectedHeap*)heap; 2706 } 2707 2708 void G1CollectedHeap::gc_prologue(bool full) { 2709 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2710 2711 // This summary needs to be printed before incrementing total collections. 2712 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2713 2714 // Update common counters. 2715 increment_total_collections(full /* full gc */); 2716 if (full || collector_state()->in_initial_mark_gc()) { 2717 increment_old_marking_cycles_started(); 2718 } 2719 2720 // Fill TLAB's and such 2721 double start = os::elapsedTime(); 2722 ensure_parsability(true); 2723 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2724 } 2725 2726 void G1CollectedHeap::gc_epilogue(bool full) { 2727 // Update common counters. 2728 if (full) { 2729 // Update the number of full collections that have been completed. 2730 increment_old_marking_cycles_completed(false /* concurrent */); 2731 } 2732 2733 // We are at the end of the GC. Total collections has already been increased. 2734 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2735 2736 // FIXME: what is this about? 2737 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2738 // is set. 2739 #if COMPILER2_OR_JVMCI 2740 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2741 #endif 2742 2743 double start = os::elapsedTime(); 2744 resize_all_tlabs(); 2745 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2746 2747 MemoryService::track_memory_usage(); 2748 // We have just completed a GC. Update the soft reference 2749 // policy with the new heap occupancy 2750 Universe::update_heap_info_at_gc(); 2751 2752 // Print NUMA statistics. 2753 _numa->print_statistics(); 2754 } 2755 2756 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2757 LogTarget(Trace, gc, heap, verify) lt; 2758 2759 if (lt.is_enabled()) { 2760 LogStream ls(lt); 2761 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2762 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2763 heap_region_iterate(&cl); 2764 } 2765 } 2766 2767 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2768 uint gc_count_before, 2769 bool* succeeded, 2770 GCCause::Cause gc_cause) { 2771 assert_heap_not_locked_and_not_at_safepoint(); 2772 VM_G1CollectForAllocation op(word_size, 2773 gc_count_before, 2774 gc_cause, 2775 policy()->max_pause_time_ms()); 2776 VMThread::execute(&op); 2777 2778 HeapWord* result = op.result(); 2779 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2780 assert(result == NULL || ret_succeeded, 2781 "the result should be NULL if the VM did not succeed"); 2782 *succeeded = ret_succeeded; 2783 2784 assert_heap_not_locked(); 2785 return result; 2786 } 2787 2788 void G1CollectedHeap::do_concurrent_mark() { 2789 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2790 if (!_cm_thread->in_progress()) { 2791 _cm_thread->set_started(); 2792 CGC_lock->notify(); 2793 } 2794 } 2795 2796 size_t G1CollectedHeap::pending_card_num() { 2797 struct CountCardsClosure : public ThreadClosure { 2798 size_t _cards; 2799 CountCardsClosure() : _cards(0) {} 2800 virtual void do_thread(Thread* t) { 2801 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2802 } 2803 } count_from_threads; 2804 Threads::threads_do(&count_from_threads); 2805 2806 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2807 return dcqs.num_cards() + count_from_threads._cards; 2808 } 2809 2810 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2811 // We don't nominate objects with many remembered set entries, on 2812 // the assumption that such objects are likely still live. 2813 HeapRegionRemSet* rem_set = r->rem_set(); 2814 2815 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2816 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2817 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2818 } 2819 2820 #ifndef PRODUCT 2821 void G1CollectedHeap::verify_region_attr_remset_update() { 2822 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2823 public: 2824 virtual bool do_heap_region(HeapRegion* r) { 2825 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2826 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2827 assert(r->rem_set()->is_tracked() == needs_remset_update, 2828 "Region %u remset tracking status (%s) different to region attribute (%s)", 2829 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2830 return false; 2831 } 2832 } cl; 2833 heap_region_iterate(&cl); 2834 } 2835 #endif 2836 2837 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2838 public: 2839 bool do_heap_region(HeapRegion* hr) { 2840 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2841 hr->verify_rem_set(); 2842 } 2843 return false; 2844 } 2845 }; 2846 2847 uint G1CollectedHeap::num_task_queues() const { 2848 return _task_queues->size(); 2849 } 2850 2851 #if TASKQUEUE_STATS 2852 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2853 st->print_raw_cr("GC Task Stats"); 2854 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2855 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2856 } 2857 2858 void G1CollectedHeap::print_taskqueue_stats() const { 2859 if (!log_is_enabled(Trace, gc, task, stats)) { 2860 return; 2861 } 2862 Log(gc, task, stats) log; 2863 ResourceMark rm; 2864 LogStream ls(log.trace()); 2865 outputStream* st = &ls; 2866 2867 print_taskqueue_stats_hdr(st); 2868 2869 TaskQueueStats totals; 2870 const uint n = num_task_queues(); 2871 for (uint i = 0; i < n; ++i) { 2872 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2873 totals += task_queue(i)->stats; 2874 } 2875 st->print_raw("tot "); totals.print(st); st->cr(); 2876 2877 DEBUG_ONLY(totals.verify()); 2878 } 2879 2880 void G1CollectedHeap::reset_taskqueue_stats() { 2881 const uint n = num_task_queues(); 2882 for (uint i = 0; i < n; ++i) { 2883 task_queue(i)->stats.reset(); 2884 } 2885 } 2886 #endif // TASKQUEUE_STATS 2887 2888 void G1CollectedHeap::wait_for_root_region_scanning() { 2889 double scan_wait_start = os::elapsedTime(); 2890 // We have to wait until the CM threads finish scanning the 2891 // root regions as it's the only way to ensure that all the 2892 // objects on them have been correctly scanned before we start 2893 // moving them during the GC. 2894 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2895 double wait_time_ms = 0.0; 2896 if (waited) { 2897 double scan_wait_end = os::elapsedTime(); 2898 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2899 } 2900 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2901 } 2902 2903 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2904 private: 2905 G1HRPrinter* _hr_printer; 2906 public: 2907 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2908 2909 virtual bool do_heap_region(HeapRegion* r) { 2910 _hr_printer->cset(r); 2911 return false; 2912 } 2913 }; 2914 2915 void G1CollectedHeap::start_new_collection_set() { 2916 double start = os::elapsedTime(); 2917 2918 collection_set()->start_incremental_building(); 2919 2920 clear_region_attr(); 2921 2922 guarantee(_eden.length() == 0, "eden should have been cleared"); 2923 policy()->transfer_survivors_to_cset(survivor()); 2924 2925 // We redo the verification but now wrt to the new CSet which 2926 // has just got initialized after the previous CSet was freed. 2927 _cm->verify_no_collection_set_oops(); 2928 2929 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2930 } 2931 2932 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2933 2934 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2935 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2936 collection_set()->optional_region_length()); 2937 2938 _cm->verify_no_collection_set_oops(); 2939 2940 if (_hr_printer.is_active()) { 2941 G1PrintCollectionSetClosure cl(&_hr_printer); 2942 _collection_set.iterate(&cl); 2943 _collection_set.iterate_optional(&cl); 2944 } 2945 } 2946 2947 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2948 if (collector_state()->in_initial_mark_gc()) { 2949 return G1HeapVerifier::G1VerifyConcurrentStart; 2950 } else if (collector_state()->in_young_only_phase()) { 2951 return G1HeapVerifier::G1VerifyYoungNormal; 2952 } else { 2953 return G1HeapVerifier::G1VerifyMixed; 2954 } 2955 } 2956 2957 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2958 if (VerifyRememberedSets) { 2959 log_info(gc, verify)("[Verifying RemSets before GC]"); 2960 VerifyRegionRemSetClosure v_cl; 2961 heap_region_iterate(&v_cl); 2962 } 2963 _verifier->verify_before_gc(type); 2964 _verifier->check_bitmaps("GC Start"); 2965 verify_numa_regions("GC Start"); 2966 } 2967 2968 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2969 if (VerifyRememberedSets) { 2970 log_info(gc, verify)("[Verifying RemSets after GC]"); 2971 VerifyRegionRemSetClosure v_cl; 2972 heap_region_iterate(&v_cl); 2973 } 2974 _verifier->verify_after_gc(type); 2975 _verifier->check_bitmaps("GC End"); 2976 verify_numa_regions("GC End"); 2977 } 2978 2979 void G1CollectedHeap::expand_heap_after_young_collection(){ 2980 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2981 if (expand_bytes > 0) { 2982 // No need for an ergo logging here, 2983 // expansion_amount() does this when it returns a value > 0. 2984 double expand_ms; 2985 if (!expand(expand_bytes, _workers, &expand_ms)) { 2986 // We failed to expand the heap. Cannot do anything about it. 2987 } 2988 phase_times()->record_expand_heap_time(expand_ms); 2989 } 2990 } 2991 2992 const char* G1CollectedHeap::young_gc_name() const { 2993 if (collector_state()->in_initial_mark_gc()) { 2994 return "Pause Young (Concurrent Start)"; 2995 } else if (collector_state()->in_young_only_phase()) { 2996 if (collector_state()->in_young_gc_before_mixed()) { 2997 return "Pause Young (Prepare Mixed)"; 2998 } else { 2999 return "Pause Young (Normal)"; 3000 } 3001 } else { 3002 return "Pause Young (Mixed)"; 3003 } 3004 } 3005 3006 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3007 assert_at_safepoint_on_vm_thread(); 3008 guarantee(!is_gc_active(), "collection is not reentrant"); 3009 3010 if (GCLocker::check_active_before_gc()) { 3011 return false; 3012 } 3013 3014 do_collection_pause_at_safepoint_helper(target_pause_time_ms); 3015 if (should_upgrade_to_full_gc(gc_cause())) { 3016 log_info(gc, ergo)("Attempting maximally compacting collection"); 3017 bool result = do_full_collection(false /* explicit gc */, 3018 true /* clear_all_soft_refs */); 3019 // do_full_collection only fails if blocked by GC locker, but 3020 // we've already checked for that above. 3021 assert(result, "invariant"); 3022 } 3023 return true; 3024 } 3025 3026 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) { 3027 GCIdMark gc_id_mark; 3028 3029 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3030 ResourceMark rm; 3031 3032 policy()->note_gc_start(); 3033 3034 _gc_timer_stw->register_gc_start(); 3035 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3036 3037 wait_for_root_region_scanning(); 3038 3039 print_heap_before_gc(); 3040 print_heap_regions(); 3041 trace_heap_before_gc(_gc_tracer_stw); 3042 3043 _verifier->verify_region_sets_optional(); 3044 _verifier->verify_dirty_young_regions(); 3045 3046 // We should not be doing initial mark unless the conc mark thread is running 3047 if (!_cm_thread->should_terminate()) { 3048 // This call will decide whether this pause is an initial-mark 3049 // pause. If it is, in_initial_mark_gc() will return true 3050 // for the duration of this pause. 3051 policy()->decide_on_conc_mark_initiation(); 3052 } 3053 3054 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3055 assert(!collector_state()->in_initial_mark_gc() || 3056 collector_state()->in_young_only_phase(), "sanity"); 3057 // We also do not allow mixed GCs during marking. 3058 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 3059 3060 // Record whether this pause is an initial mark. When the current 3061 // thread has completed its logging output and it's safe to signal 3062 // the CM thread, the flag's value in the policy has been reset. 3063 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 3064 if (should_start_conc_mark) { 3065 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3066 } 3067 3068 // Inner scope for scope based logging, timers, and stats collection 3069 { 3070 G1EvacuationInfo evacuation_info; 3071 3072 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3073 3074 GCTraceCPUTime tcpu; 3075 3076 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3077 3078 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3079 workers()->active_workers(), 3080 Threads::number_of_non_daemon_threads()); 3081 active_workers = workers()->update_active_workers(active_workers); 3082 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3083 3084 G1MonitoringScope ms(g1mm(), 3085 false /* full_gc */, 3086 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3087 3088 G1HeapTransition heap_transition(this); 3089 3090 { 3091 IsGCActiveMark x; 3092 3093 gc_prologue(false); 3094 3095 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3096 verify_before_young_collection(verify_type); 3097 3098 { 3099 // The elapsed time induced by the start time below deliberately elides 3100 // the possible verification above. 3101 double sample_start_time_sec = os::elapsedTime(); 3102 3103 // Please see comment in g1CollectedHeap.hpp and 3104 // G1CollectedHeap::ref_processing_init() to see how 3105 // reference processing currently works in G1. 3106 _ref_processor_stw->enable_discovery(); 3107 3108 // We want to temporarily turn off discovery by the 3109 // CM ref processor, if necessary, and turn it back on 3110 // on again later if we do. Using a scoped 3111 // NoRefDiscovery object will do this. 3112 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3113 3114 policy()->record_collection_pause_start(sample_start_time_sec); 3115 3116 // Forget the current allocation region (we might even choose it to be part 3117 // of the collection set!). 3118 _allocator->release_mutator_alloc_regions(); 3119 3120 calculate_collection_set(evacuation_info, target_pause_time_ms); 3121 3122 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3123 G1ParScanThreadStateSet per_thread_states(this, 3124 &rdcqs, 3125 workers()->active_workers(), 3126 collection_set()->young_region_length(), 3127 collection_set()->optional_region_length()); 3128 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3129 3130 // Actually do the work... 3131 evacuate_initial_collection_set(&per_thread_states); 3132 3133 if (_collection_set.optional_region_length() != 0) { 3134 evacuate_optional_collection_set(&per_thread_states); 3135 } 3136 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3137 3138 start_new_collection_set(); 3139 3140 _survivor_evac_stats.adjust_desired_plab_sz(); 3141 _old_evac_stats.adjust_desired_plab_sz(); 3142 3143 if (should_start_conc_mark) { 3144 // We have to do this before we notify the CM threads that 3145 // they can start working to make sure that all the 3146 // appropriate initialization is done on the CM object. 3147 concurrent_mark()->post_initial_mark(); 3148 // Note that we don't actually trigger the CM thread at 3149 // this point. We do that later when we're sure that 3150 // the current thread has completed its logging output. 3151 } 3152 3153 allocate_dummy_regions(); 3154 3155 _allocator->init_mutator_alloc_regions(); 3156 3157 expand_heap_after_young_collection(); 3158 3159 double sample_end_time_sec = os::elapsedTime(); 3160 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3161 policy()->record_collection_pause_end(pause_time_ms); 3162 } 3163 3164 verify_after_young_collection(verify_type); 3165 3166 gc_epilogue(false); 3167 } 3168 3169 // Print the remainder of the GC log output. 3170 if (evacuation_failed()) { 3171 log_info(gc)("To-space exhausted"); 3172 } 3173 3174 policy()->print_phases(); 3175 heap_transition.print(); 3176 3177 _hrm->verify_optional(); 3178 _verifier->verify_region_sets_optional(); 3179 3180 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3181 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3182 3183 print_heap_after_gc(); 3184 print_heap_regions(); 3185 trace_heap_after_gc(_gc_tracer_stw); 3186 3187 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3188 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3189 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3190 // before any GC notifications are raised. 3191 g1mm()->update_sizes(); 3192 3193 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3194 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3195 _gc_timer_stw->register_gc_end(); 3196 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3197 } 3198 // It should now be safe to tell the concurrent mark thread to start 3199 // without its logging output interfering with the logging output 3200 // that came from the pause. 3201 3202 if (should_start_conc_mark) { 3203 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3204 // thread(s) could be running concurrently with us. Make sure that anything 3205 // after this point does not assume that we are the only GC thread running. 3206 // Note: of course, the actual marking work will not start until the safepoint 3207 // itself is released in SuspendibleThreadSet::desynchronize(). 3208 do_concurrent_mark(); 3209 ConcurrentGCBreakpoints::notify_idle_to_active(); 3210 } 3211 } 3212 3213 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3214 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3215 workers()->run_task(&rsfp_task); 3216 } 3217 3218 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3219 double remove_self_forwards_start = os::elapsedTime(); 3220 3221 remove_self_forwarding_pointers(rdcqs); 3222 _preserved_marks_set.restore(workers()); 3223 3224 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3225 } 3226 3227 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3228 if (!_evacuation_failed) { 3229 _evacuation_failed = true; 3230 } 3231 3232 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3233 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3234 } 3235 3236 bool G1ParEvacuateFollowersClosure::offer_termination() { 3237 EventGCPhaseParallel event; 3238 G1ParScanThreadState* const pss = par_scan_state(); 3239 start_term_time(); 3240 const bool res = terminator()->offer_termination(); 3241 end_term_time(); 3242 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3243 return res; 3244 } 3245 3246 void G1ParEvacuateFollowersClosure::do_void() { 3247 EventGCPhaseParallel event; 3248 G1ParScanThreadState* const pss = par_scan_state(); 3249 pss->trim_queue(); 3250 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3251 do { 3252 EventGCPhaseParallel event; 3253 pss->steal_and_trim_queue(queues()); 3254 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3255 } while (!offer_termination()); 3256 } 3257 3258 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3259 bool class_unloading_occurred) { 3260 uint num_workers = workers()->active_workers(); 3261 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3262 workers()->run_task(&unlink_task); 3263 } 3264 3265 // Clean string dedup data structures. 3266 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3267 // record the durations of the phases. Hence the almost-copy. 3268 class G1StringDedupCleaningTask : public AbstractGangTask { 3269 BoolObjectClosure* _is_alive; 3270 OopClosure* _keep_alive; 3271 G1GCPhaseTimes* _phase_times; 3272 3273 public: 3274 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3275 OopClosure* keep_alive, 3276 G1GCPhaseTimes* phase_times) : 3277 AbstractGangTask("Partial Cleaning Task"), 3278 _is_alive(is_alive), 3279 _keep_alive(keep_alive), 3280 _phase_times(phase_times) 3281 { 3282 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3283 StringDedup::gc_prologue(true); 3284 } 3285 3286 ~G1StringDedupCleaningTask() { 3287 StringDedup::gc_epilogue(); 3288 } 3289 3290 void work(uint worker_id) { 3291 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3292 { 3293 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3294 StringDedupQueue::unlink_or_oops_do(&cl); 3295 } 3296 { 3297 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3298 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3299 } 3300 } 3301 }; 3302 3303 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3304 OopClosure* keep_alive, 3305 G1GCPhaseTimes* phase_times) { 3306 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3307 workers()->run_task(&cl); 3308 } 3309 3310 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3311 private: 3312 G1RedirtyCardsQueueSet* _qset; 3313 G1CollectedHeap* _g1h; 3314 BufferNode* volatile _nodes; 3315 3316 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3317 size_t buffer_size = _qset->buffer_size(); 3318 BufferNode* next = Atomic::load(&_nodes); 3319 while (next != NULL) { 3320 BufferNode* node = next; 3321 next = Atomic::cmpxchg(&_nodes, node, node->next()); 3322 if (next == node) { 3323 cl->apply_to_buffer(node, buffer_size, worker_id); 3324 next = node->next(); 3325 } 3326 } 3327 } 3328 3329 public: 3330 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3331 AbstractGangTask("Redirty Cards"), 3332 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3333 3334 virtual void work(uint worker_id) { 3335 G1GCPhaseTimes* p = _g1h->phase_times(); 3336 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3337 3338 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3339 par_apply(&cl, worker_id); 3340 3341 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3342 } 3343 }; 3344 3345 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3346 double redirty_logged_cards_start = os::elapsedTime(); 3347 3348 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3349 workers()->run_task(&redirty_task); 3350 3351 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3352 dcq.merge_bufferlists(rdcqs); 3353 3354 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3355 } 3356 3357 // Weak Reference Processing support 3358 3359 bool G1STWIsAliveClosure::do_object_b(oop p) { 3360 // An object is reachable if it is outside the collection set, 3361 // or is inside and copied. 3362 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3363 } 3364 3365 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3366 assert(obj != NULL, "must not be NULL"); 3367 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3368 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3369 // may falsely indicate that this is not the case here: however the collection set only 3370 // contains old regions when concurrent mark is not running. 3371 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3372 } 3373 3374 // Non Copying Keep Alive closure 3375 class G1KeepAliveClosure: public OopClosure { 3376 G1CollectedHeap*_g1h; 3377 public: 3378 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3379 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3380 void do_oop(oop* p) { 3381 oop obj = *p; 3382 assert(obj != NULL, "the caller should have filtered out NULL values"); 3383 3384 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3385 if (!region_attr.is_in_cset_or_humongous()) { 3386 return; 3387 } 3388 if (region_attr.is_in_cset()) { 3389 assert( obj->is_forwarded(), "invariant" ); 3390 *p = obj->forwardee(); 3391 } else { 3392 assert(!obj->is_forwarded(), "invariant" ); 3393 assert(region_attr.is_humongous(), 3394 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3395 _g1h->set_humongous_is_live(obj); 3396 } 3397 } 3398 }; 3399 3400 // Copying Keep Alive closure - can be called from both 3401 // serial and parallel code as long as different worker 3402 // threads utilize different G1ParScanThreadState instances 3403 // and different queues. 3404 3405 class G1CopyingKeepAliveClosure: public OopClosure { 3406 G1CollectedHeap* _g1h; 3407 G1ParScanThreadState* _par_scan_state; 3408 3409 public: 3410 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3411 G1ParScanThreadState* pss): 3412 _g1h(g1h), 3413 _par_scan_state(pss) 3414 {} 3415 3416 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3417 virtual void do_oop( oop* p) { do_oop_work(p); } 3418 3419 template <class T> void do_oop_work(T* p) { 3420 oop obj = RawAccess<>::oop_load(p); 3421 3422 if (_g1h->is_in_cset_or_humongous(obj)) { 3423 // If the referent object has been forwarded (either copied 3424 // to a new location or to itself in the event of an 3425 // evacuation failure) then we need to update the reference 3426 // field and, if both reference and referent are in the G1 3427 // heap, update the RSet for the referent. 3428 // 3429 // If the referent has not been forwarded then we have to keep 3430 // it alive by policy. Therefore we have copy the referent. 3431 // 3432 // When the queue is drained (after each phase of reference processing) 3433 // the object and it's followers will be copied, the reference field set 3434 // to point to the new location, and the RSet updated. 3435 _par_scan_state->push_on_queue(p); 3436 } 3437 } 3438 }; 3439 3440 // Serial drain queue closure. Called as the 'complete_gc' 3441 // closure for each discovered list in some of the 3442 // reference processing phases. 3443 3444 class G1STWDrainQueueClosure: public VoidClosure { 3445 protected: 3446 G1CollectedHeap* _g1h; 3447 G1ParScanThreadState* _par_scan_state; 3448 3449 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3450 3451 public: 3452 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3453 _g1h(g1h), 3454 _par_scan_state(pss) 3455 { } 3456 3457 void do_void() { 3458 G1ParScanThreadState* const pss = par_scan_state(); 3459 pss->trim_queue(); 3460 } 3461 }; 3462 3463 // Parallel Reference Processing closures 3464 3465 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3466 // processing during G1 evacuation pauses. 3467 3468 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3469 private: 3470 G1CollectedHeap* _g1h; 3471 G1ParScanThreadStateSet* _pss; 3472 RefToScanQueueSet* _queues; 3473 WorkGang* _workers; 3474 3475 public: 3476 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3477 G1ParScanThreadStateSet* per_thread_states, 3478 WorkGang* workers, 3479 RefToScanQueueSet *task_queues) : 3480 _g1h(g1h), 3481 _pss(per_thread_states), 3482 _queues(task_queues), 3483 _workers(workers) 3484 { 3485 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3486 } 3487 3488 // Executes the given task using concurrent marking worker threads. 3489 virtual void execute(ProcessTask& task, uint ergo_workers); 3490 }; 3491 3492 // Gang task for possibly parallel reference processing 3493 3494 class G1STWRefProcTaskProxy: public AbstractGangTask { 3495 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3496 ProcessTask& _proc_task; 3497 G1CollectedHeap* _g1h; 3498 G1ParScanThreadStateSet* _pss; 3499 RefToScanQueueSet* _task_queues; 3500 TaskTerminator* _terminator; 3501 3502 public: 3503 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3504 G1CollectedHeap* g1h, 3505 G1ParScanThreadStateSet* per_thread_states, 3506 RefToScanQueueSet *task_queues, 3507 TaskTerminator* terminator) : 3508 AbstractGangTask("Process reference objects in parallel"), 3509 _proc_task(proc_task), 3510 _g1h(g1h), 3511 _pss(per_thread_states), 3512 _task_queues(task_queues), 3513 _terminator(terminator) 3514 {} 3515 3516 virtual void work(uint worker_id) { 3517 // The reference processing task executed by a single worker. 3518 ResourceMark rm; 3519 HandleMark hm; 3520 3521 G1STWIsAliveClosure is_alive(_g1h); 3522 3523 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3524 pss->set_ref_discoverer(NULL); 3525 3526 // Keep alive closure. 3527 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3528 3529 // Complete GC closure 3530 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3531 3532 // Call the reference processing task's work routine. 3533 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3534 3535 // Note we cannot assert that the refs array is empty here as not all 3536 // of the processing tasks (specifically phase2 - pp2_work) execute 3537 // the complete_gc closure (which ordinarily would drain the queue) so 3538 // the queue may not be empty. 3539 } 3540 }; 3541 3542 // Driver routine for parallel reference processing. 3543 // Creates an instance of the ref processing gang 3544 // task and has the worker threads execute it. 3545 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3546 assert(_workers != NULL, "Need parallel worker threads."); 3547 3548 assert(_workers->active_workers() >= ergo_workers, 3549 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3550 ergo_workers, _workers->active_workers()); 3551 TaskTerminator terminator(ergo_workers, _queues); 3552 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3553 3554 _workers->run_task(&proc_task_proxy, ergo_workers); 3555 } 3556 3557 // End of weak reference support closures 3558 3559 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3560 double ref_proc_start = os::elapsedTime(); 3561 3562 ReferenceProcessor* rp = _ref_processor_stw; 3563 assert(rp->discovery_enabled(), "should have been enabled"); 3564 3565 // Closure to test whether a referent is alive. 3566 G1STWIsAliveClosure is_alive(this); 3567 3568 // Even when parallel reference processing is enabled, the processing 3569 // of JNI refs is serial and performed serially by the current thread 3570 // rather than by a worker. The following PSS will be used for processing 3571 // JNI refs. 3572 3573 // Use only a single queue for this PSS. 3574 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3575 pss->set_ref_discoverer(NULL); 3576 assert(pss->queue_is_empty(), "pre-condition"); 3577 3578 // Keep alive closure. 3579 G1CopyingKeepAliveClosure keep_alive(this, pss); 3580 3581 // Serial Complete GC closure 3582 G1STWDrainQueueClosure drain_queue(this, pss); 3583 3584 // Setup the soft refs policy... 3585 rp->setup_policy(false); 3586 3587 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3588 3589 ReferenceProcessorStats stats; 3590 if (!rp->processing_is_mt()) { 3591 // Serial reference processing... 3592 stats = rp->process_discovered_references(&is_alive, 3593 &keep_alive, 3594 &drain_queue, 3595 NULL, 3596 pt); 3597 } else { 3598 uint no_of_gc_workers = workers()->active_workers(); 3599 3600 // Parallel reference processing 3601 assert(no_of_gc_workers <= rp->max_num_queues(), 3602 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3603 no_of_gc_workers, rp->max_num_queues()); 3604 3605 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3606 stats = rp->process_discovered_references(&is_alive, 3607 &keep_alive, 3608 &drain_queue, 3609 &par_task_executor, 3610 pt); 3611 } 3612 3613 _gc_tracer_stw->report_gc_reference_stats(stats); 3614 3615 // We have completed copying any necessary live referent objects. 3616 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3617 3618 make_pending_list_reachable(); 3619 3620 assert(!rp->discovery_enabled(), "Postcondition"); 3621 rp->verify_no_references_recorded(); 3622 3623 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3624 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3625 } 3626 3627 void G1CollectedHeap::make_pending_list_reachable() { 3628 if (collector_state()->in_initial_mark_gc()) { 3629 oop pll_head = Universe::reference_pending_list(); 3630 if (pll_head != NULL) { 3631 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3632 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3633 } 3634 } 3635 } 3636 3637 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3638 Ticks start = Ticks::now(); 3639 per_thread_states->flush(); 3640 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds()); 3641 } 3642 3643 class G1PrepareEvacuationTask : public AbstractGangTask { 3644 class G1PrepareRegionsClosure : public HeapRegionClosure { 3645 G1CollectedHeap* _g1h; 3646 G1PrepareEvacuationTask* _parent_task; 3647 size_t _worker_humongous_total; 3648 size_t _worker_humongous_candidates; 3649 3650 bool humongous_region_is_candidate(HeapRegion* region) const { 3651 assert(region->is_starts_humongous(), "Must start a humongous object"); 3652 3653 oop obj = oop(region->bottom()); 3654 3655 // Dead objects cannot be eager reclaim candidates. Due to class 3656 // unloading it is unsafe to query their classes so we return early. 3657 if (_g1h->is_obj_dead(obj, region)) { 3658 return false; 3659 } 3660 3661 // If we do not have a complete remembered set for the region, then we can 3662 // not be sure that we have all references to it. 3663 if (!region->rem_set()->is_complete()) { 3664 return false; 3665 } 3666 // Candidate selection must satisfy the following constraints 3667 // while concurrent marking is in progress: 3668 // 3669 // * In order to maintain SATB invariants, an object must not be 3670 // reclaimed if it was allocated before the start of marking and 3671 // has not had its references scanned. Such an object must have 3672 // its references (including type metadata) scanned to ensure no 3673 // live objects are missed by the marking process. Objects 3674 // allocated after the start of concurrent marking don't need to 3675 // be scanned. 3676 // 3677 // * An object must not be reclaimed if it is on the concurrent 3678 // mark stack. Objects allocated after the start of concurrent 3679 // marking are never pushed on the mark stack. 3680 // 3681 // Nominating only objects allocated after the start of concurrent 3682 // marking is sufficient to meet both constraints. This may miss 3683 // some objects that satisfy the constraints, but the marking data 3684 // structures don't support efficiently performing the needed 3685 // additional tests or scrubbing of the mark stack. 3686 // 3687 // However, we presently only nominate is_typeArray() objects. 3688 // A humongous object containing references induces remembered 3689 // set entries on other regions. In order to reclaim such an 3690 // object, those remembered sets would need to be cleaned up. 3691 // 3692 // We also treat is_typeArray() objects specially, allowing them 3693 // to be reclaimed even if allocated before the start of 3694 // concurrent mark. For this we rely on mark stack insertion to 3695 // exclude is_typeArray() objects, preventing reclaiming an object 3696 // that is in the mark stack. We also rely on the metadata for 3697 // such objects to be built-in and so ensured to be kept live. 3698 // Frequent allocation and drop of large binary blobs is an 3699 // important use case for eager reclaim, and this special handling 3700 // may reduce needed headroom. 3701 3702 return obj->is_typeArray() && 3703 _g1h->is_potential_eager_reclaim_candidate(region); 3704 } 3705 3706 public: 3707 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) : 3708 _g1h(g1h), 3709 _parent_task(parent_task), 3710 _worker_humongous_total(0), 3711 _worker_humongous_candidates(0) { } 3712 3713 ~G1PrepareRegionsClosure() { 3714 _parent_task->add_humongous_candidates(_worker_humongous_candidates); 3715 _parent_task->add_humongous_total(_worker_humongous_total); 3716 } 3717 3718 virtual bool do_heap_region(HeapRegion* hr) { 3719 // First prepare the region for scanning 3720 _g1h->rem_set()->prepare_region_for_scan(hr); 3721 3722 // Now check if region is a humongous candidate 3723 if (!hr->is_starts_humongous()) { 3724 _g1h->register_region_with_region_attr(hr); 3725 return false; 3726 } 3727 3728 uint index = hr->hrm_index(); 3729 if (humongous_region_is_candidate(hr)) { 3730 _g1h->set_humongous_reclaim_candidate(index, true); 3731 _g1h->register_humongous_region_with_region_attr(index); 3732 _worker_humongous_candidates++; 3733 // We will later handle the remembered sets of these regions. 3734 } else { 3735 _g1h->set_humongous_reclaim_candidate(index, false); 3736 _g1h->register_region_with_region_attr(hr); 3737 } 3738 _worker_humongous_total++; 3739 3740 return false; 3741 } 3742 }; 3743 3744 G1CollectedHeap* _g1h; 3745 HeapRegionClaimer _claimer; 3746 volatile size_t _humongous_total; 3747 volatile size_t _humongous_candidates; 3748 public: 3749 G1PrepareEvacuationTask(G1CollectedHeap* g1h) : 3750 AbstractGangTask("Prepare Evacuation"), 3751 _g1h(g1h), 3752 _claimer(_g1h->workers()->active_workers()), 3753 _humongous_total(0), 3754 _humongous_candidates(0) { } 3755 3756 ~G1PrepareEvacuationTask() { 3757 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0); 3758 } 3759 3760 void work(uint worker_id) { 3761 G1PrepareRegionsClosure cl(_g1h, this); 3762 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id); 3763 } 3764 3765 void add_humongous_candidates(size_t candidates) { 3766 Atomic::add(&_humongous_candidates, candidates); 3767 } 3768 3769 void add_humongous_total(size_t total) { 3770 Atomic::add(&_humongous_total, total); 3771 } 3772 3773 size_t humongous_candidates() { 3774 return _humongous_candidates; 3775 } 3776 3777 size_t humongous_total() { 3778 return _humongous_total; 3779 } 3780 }; 3781 3782 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3783 _bytes_used_during_gc = 0; 3784 3785 _expand_heap_after_alloc_failure = true; 3786 _evacuation_failed = false; 3787 3788 // Disable the hot card cache. 3789 _hot_card_cache->reset_hot_cache_claimed_index(); 3790 _hot_card_cache->set_use_cache(false); 3791 3792 // Initialize the GC alloc regions. 3793 _allocator->init_gc_alloc_regions(evacuation_info); 3794 3795 { 3796 Ticks start = Ticks::now(); 3797 rem_set()->prepare_for_scan_heap_roots(); 3798 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3799 } 3800 3801 { 3802 G1PrepareEvacuationTask g1_prep_task(this); 3803 Tickspan task_time = run_task(&g1_prep_task); 3804 3805 phase_times()->record_register_regions(task_time.seconds() * 1000.0, 3806 g1_prep_task.humongous_total(), 3807 g1_prep_task.humongous_candidates()); 3808 } 3809 3810 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3811 _preserved_marks_set.assert_empty(); 3812 3813 #if COMPILER2_OR_JVMCI 3814 DerivedPointerTable::clear(); 3815 #endif 3816 3817 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3818 if (collector_state()->in_initial_mark_gc()) { 3819 concurrent_mark()->pre_initial_mark(); 3820 3821 double start_clear_claimed_marks = os::elapsedTime(); 3822 3823 ClassLoaderDataGraph::clear_claimed_marks(); 3824 3825 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3826 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3827 } 3828 3829 // Should G1EvacuationFailureALot be in effect for this GC? 3830 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3831 } 3832 3833 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3834 protected: 3835 G1CollectedHeap* _g1h; 3836 G1ParScanThreadStateSet* _per_thread_states; 3837 RefToScanQueueSet* _task_queues; 3838 TaskTerminator _terminator; 3839 uint _num_workers; 3840 3841 void evacuate_live_objects(G1ParScanThreadState* pss, 3842 uint worker_id, 3843 G1GCPhaseTimes::GCParPhases objcopy_phase, 3844 G1GCPhaseTimes::GCParPhases termination_phase) { 3845 G1GCPhaseTimes* p = _g1h->phase_times(); 3846 3847 Ticks start = Ticks::now(); 3848 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase); 3849 cl.do_void(); 3850 3851 assert(pss->queue_is_empty(), "should be empty"); 3852 3853 Tickspan evac_time = (Ticks::now() - start); 3854 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3855 3856 if (termination_phase == G1GCPhaseTimes::Termination) { 3857 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3858 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3859 } else { 3860 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3861 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3862 } 3863 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3864 } 3865 3866 virtual void start_work(uint worker_id) { } 3867 3868 virtual void end_work(uint worker_id) { } 3869 3870 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3871 3872 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3873 3874 public: 3875 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3876 AbstractGangTask(name), 3877 _g1h(G1CollectedHeap::heap()), 3878 _per_thread_states(per_thread_states), 3879 _task_queues(task_queues), 3880 _terminator(num_workers, _task_queues), 3881 _num_workers(num_workers) 3882 { } 3883 3884 void work(uint worker_id) { 3885 start_work(worker_id); 3886 3887 { 3888 ResourceMark rm; 3889 HandleMark hm; 3890 3891 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3892 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3893 3894 scan_roots(pss, worker_id); 3895 evacuate_live_objects(pss, worker_id); 3896 } 3897 3898 end_work(worker_id); 3899 } 3900 }; 3901 3902 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3903 G1RootProcessor* _root_processor; 3904 3905 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3906 _root_processor->evacuate_roots(pss, worker_id); 3907 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3908 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3909 } 3910 3911 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3912 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3913 } 3914 3915 void start_work(uint worker_id) { 3916 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3917 } 3918 3919 void end_work(uint worker_id) { 3920 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3921 } 3922 3923 public: 3924 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3925 G1ParScanThreadStateSet* per_thread_states, 3926 RefToScanQueueSet* task_queues, 3927 G1RootProcessor* root_processor, 3928 uint num_workers) : 3929 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3930 _root_processor(root_processor) 3931 { } 3932 }; 3933 3934 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3935 G1GCPhaseTimes* p = phase_times(); 3936 3937 { 3938 Ticks start = Ticks::now(); 3939 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3940 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3941 } 3942 3943 Tickspan task_time; 3944 const uint num_workers = workers()->active_workers(); 3945 3946 Ticks start_processing = Ticks::now(); 3947 { 3948 G1RootProcessor root_processor(this, num_workers); 3949 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3950 task_time = run_task(&g1_par_task); 3951 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3952 // To extract its code root fixup time we measure total time of this scope and 3953 // subtract from the time the WorkGang task took. 3954 } 3955 Tickspan total_processing = Ticks::now() - start_processing; 3956 3957 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3958 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3959 } 3960 3961 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3962 3963 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3964 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3965 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3966 } 3967 3968 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3969 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3970 } 3971 3972 public: 3973 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3974 RefToScanQueueSet* queues, 3975 uint num_workers) : 3976 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3977 } 3978 }; 3979 3980 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3981 class G1MarkScope : public MarkScope { }; 3982 3983 Tickspan task_time; 3984 3985 Ticks start_processing = Ticks::now(); 3986 { 3987 G1MarkScope code_mark_scope; 3988 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3989 task_time = run_task(&task); 3990 // See comment in evacuate_collection_set() for the reason of the scope. 3991 } 3992 Tickspan total_processing = Ticks::now() - start_processing; 3993 3994 G1GCPhaseTimes* p = phase_times(); 3995 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3996 } 3997 3998 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3999 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 4000 4001 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 4002 4003 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 4004 double time_left_ms = MaxGCPauseMillis - time_used_ms; 4005 4006 if (time_left_ms < 0 || 4007 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 4008 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 4009 _collection_set.optional_region_length(), time_left_ms); 4010 break; 4011 } 4012 4013 { 4014 Ticks start = Ticks::now(); 4015 rem_set()->merge_heap_roots(false /* initial_evacuation */); 4016 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 4017 } 4018 4019 { 4020 Ticks start = Ticks::now(); 4021 evacuate_next_optional_regions(per_thread_states); 4022 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 4023 } 4024 } 4025 4026 _collection_set.abandon_optional_collection_set(per_thread_states); 4027 } 4028 4029 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 4030 G1RedirtyCardsQueueSet* rdcqs, 4031 G1ParScanThreadStateSet* per_thread_states) { 4032 G1GCPhaseTimes* p = phase_times(); 4033 4034 rem_set()->cleanup_after_scan_heap_roots(); 4035 4036 // Process any discovered reference objects - we have 4037 // to do this _before_ we retire the GC alloc regions 4038 // as we may have to copy some 'reachable' referent 4039 // objects (and their reachable sub-graphs) that were 4040 // not copied during the pause. 4041 process_discovered_references(per_thread_states); 4042 4043 G1STWIsAliveClosure is_alive(this); 4044 G1KeepAliveClosure keep_alive(this); 4045 4046 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times()); 4047 4048 if (G1StringDedup::is_enabled()) { 4049 double string_dedup_time_ms = os::elapsedTime(); 4050 4051 string_dedup_cleaning(&is_alive, &keep_alive, p); 4052 4053 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 4054 p->record_string_deduplication_time(string_cleanup_time_ms); 4055 } 4056 4057 _allocator->release_gc_alloc_regions(evacuation_info); 4058 4059 if (evacuation_failed()) { 4060 restore_after_evac_failure(rdcqs); 4061 4062 // Reset the G1EvacuationFailureALot counters and flags 4063 NOT_PRODUCT(reset_evacuation_should_fail();) 4064 4065 double recalculate_used_start = os::elapsedTime(); 4066 set_used(recalculate_used()); 4067 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 4068 4069 if (_archive_allocator != NULL) { 4070 _archive_allocator->clear_used(); 4071 } 4072 for (uint i = 0; i < ParallelGCThreads; i++) { 4073 if (_evacuation_failed_info_array[i].has_failed()) { 4074 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4075 } 4076 } 4077 } else { 4078 // The "used" of the the collection set have already been subtracted 4079 // when they were freed. Add in the bytes used. 4080 increase_used(_bytes_used_during_gc); 4081 } 4082 4083 _preserved_marks_set.assert_empty(); 4084 4085 merge_per_thread_state_info(per_thread_states); 4086 4087 // Reset and re-enable the hot card cache. 4088 // Note the counts for the cards in the regions in the 4089 // collection set are reset when the collection set is freed. 4090 _hot_card_cache->reset_hot_cache(); 4091 _hot_card_cache->set_use_cache(true); 4092 4093 purge_code_root_memory(); 4094 4095 redirty_logged_cards(rdcqs); 4096 4097 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4098 4099 eagerly_reclaim_humongous_regions(); 4100 4101 record_obj_copy_mem_stats(); 4102 4103 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4104 evacuation_info.set_bytes_used(_bytes_used_during_gc); 4105 4106 #if COMPILER2_OR_JVMCI 4107 double start = os::elapsedTime(); 4108 DerivedPointerTable::update_pointers(); 4109 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4110 #endif 4111 policy()->print_age_table(); 4112 } 4113 4114 void G1CollectedHeap::record_obj_copy_mem_stats() { 4115 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4116 4117 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4118 create_g1_evac_summary(&_old_evac_stats)); 4119 } 4120 4121 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 4122 assert(!hr->is_free(), "the region should not be free"); 4123 assert(!hr->is_empty(), "the region should not be empty"); 4124 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4125 4126 if (G1VerifyBitmaps) { 4127 MemRegion mr(hr->bottom(), hr->end()); 4128 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4129 } 4130 4131 // Clear the card counts for this region. 4132 // Note: we only need to do this if the region is not young 4133 // (since we don't refine cards in young regions). 4134 if (!hr->is_young()) { 4135 _hot_card_cache->reset_card_counts(hr); 4136 } 4137 4138 // Reset region metadata to allow reuse. 4139 hr->hr_clear(true /* clear_space */); 4140 _policy->remset_tracker()->update_at_free(hr); 4141 4142 if (free_list != NULL) { 4143 free_list->add_ordered(hr); 4144 } 4145 } 4146 4147 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4148 FreeRegionList* free_list) { 4149 assert(hr->is_humongous(), "this is only for humongous regions"); 4150 assert(free_list != NULL, "pre-condition"); 4151 hr->clear_humongous(); 4152 free_region(hr, free_list); 4153 } 4154 4155 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4156 const uint humongous_regions_removed) { 4157 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4158 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4159 _old_set.bulk_remove(old_regions_removed); 4160 _humongous_set.bulk_remove(humongous_regions_removed); 4161 } 4162 4163 } 4164 4165 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4166 assert(list != NULL, "list can't be null"); 4167 if (!list->is_empty()) { 4168 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4169 _hrm->insert_list_into_free_list(list); 4170 } 4171 } 4172 4173 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4174 decrease_used(bytes); 4175 } 4176 4177 class G1FreeCollectionSetTask : public AbstractGangTask { 4178 // Helper class to keep statistics for the collection set freeing 4179 class FreeCSetStats { 4180 size_t _before_used_bytes; // Usage in regions successfully evacutate 4181 size_t _after_used_bytes; // Usage in regions failing evacuation 4182 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old 4183 size_t _failure_used_words; // Live size in failed regions 4184 size_t _failure_waste_words; // Wasted size in failed regions 4185 size_t _rs_length; // Remembered set size 4186 uint _regions_freed; // Number of regions freed 4187 public: 4188 FreeCSetStats() : 4189 _before_used_bytes(0), 4190 _after_used_bytes(0), 4191 _bytes_allocated_in_old_since_last_gc(0), 4192 _failure_used_words(0), 4193 _failure_waste_words(0), 4194 _rs_length(0), 4195 _regions_freed(0) { } 4196 4197 void merge_stats(FreeCSetStats* other) { 4198 assert(other != NULL, "invariant"); 4199 _before_used_bytes += other->_before_used_bytes; 4200 _after_used_bytes += other->_after_used_bytes; 4201 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc; 4202 _failure_used_words += other->_failure_used_words; 4203 _failure_waste_words += other->_failure_waste_words; 4204 _rs_length += other->_rs_length; 4205 _regions_freed += other->_regions_freed; 4206 } 4207 4208 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) { 4209 evacuation_info->set_regions_freed(_regions_freed); 4210 evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4211 4212 g1h->decrement_summary_bytes(_before_used_bytes); 4213 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4214 4215 G1Policy *policy = g1h->policy(); 4216 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4217 policy->record_rs_length(_rs_length); 4218 policy->cset_regions_freed(); 4219 } 4220 4221 void account_failed_region(HeapRegion* r) { 4222 size_t used_words = r->marked_bytes() / HeapWordSize; 4223 _failure_used_words += used_words; 4224 _failure_waste_words += HeapRegion::GrainWords - used_words; 4225 _after_used_bytes += r->used(); 4226 4227 // When moving a young gen region to old gen, we "allocate" that whole 4228 // region there. This is in addition to any already evacuated objects. 4229 // Notify the policy about that. Old gen regions do not cause an 4230 // additional allocation: both the objects still in the region and the 4231 // ones already moved are accounted for elsewhere. 4232 if (r->is_young()) { 4233 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4234 } 4235 } 4236 4237 void account_evacuated_region(HeapRegion* r) { 4238 _before_used_bytes += r->used(); 4239 _regions_freed += 1; 4240 } 4241 4242 void account_rs_length(HeapRegion* r) { 4243 _rs_length += r->rem_set()->occupied(); 4244 } 4245 }; 4246 4247 // Closure applied to all regions in the collection set. 4248 class FreeCSetClosure : public HeapRegionClosure { 4249 // Helper to send JFR events for regions. 4250 class JFREventForRegion { 4251 EventGCPhaseParallel _event; 4252 public: 4253 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() { 4254 _event.set_gcId(GCId::current()); 4255 _event.set_gcWorkerId(worker_id); 4256 if (region->is_young()) { 4257 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4258 } else { 4259 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4260 } 4261 } 4262 4263 ~JFREventForRegion() { 4264 _event.commit(); 4265 } 4266 }; 4267 4268 // Helper to do timing for region work. 4269 class TimerForRegion { 4270 Tickspan& _time; 4271 Ticks _start_time; 4272 public: 4273 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { } 4274 ~TimerForRegion() { 4275 _time += Ticks::now() - _start_time; 4276 } 4277 }; 4278 4279 // FreeCSetClosure members 4280 G1CollectedHeap* _g1h; 4281 const size_t* _surviving_young_words; 4282 uint _worker_id; 4283 Tickspan _young_time; 4284 Tickspan _non_young_time; 4285 FreeCSetStats* _stats; 4286 4287 void assert_in_cset(HeapRegion* r) { 4288 assert(r->young_index_in_cset() != 0 && 4289 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(), 4290 "Young index %u is wrong for region %u of type %s with %u young regions", 4291 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length()); 4292 } 4293 4294 void handle_evacuated_region(HeapRegion* r) { 4295 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4296 stats()->account_evacuated_region(r); 4297 4298 // Free the region and and its remembered set. 4299 _g1h->free_region(r, NULL); 4300 } 4301 4302 void handle_failed_region(HeapRegion* r) { 4303 // Do some allocation statistics accounting. Regions that failed evacuation 4304 // are always made old, so there is no need to update anything in the young 4305 // gen statistics, but we need to update old gen statistics. 4306 stats()->account_failed_region(r); 4307 4308 // Update the region state due to the failed evacuation. 4309 r->handle_evacuation_failure(); 4310 4311 // Add region to old set, need to hold lock. 4312 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4313 _g1h->old_set_add(r); 4314 } 4315 4316 Tickspan& timer_for_region(HeapRegion* r) { 4317 return r->is_young() ? _young_time : _non_young_time; 4318 } 4319 4320 FreeCSetStats* stats() { 4321 return _stats; 4322 } 4323 public: 4324 FreeCSetClosure(const size_t* surviving_young_words, 4325 uint worker_id, 4326 FreeCSetStats* stats) : 4327 HeapRegionClosure(), 4328 _g1h(G1CollectedHeap::heap()), 4329 _surviving_young_words(surviving_young_words), 4330 _worker_id(worker_id), 4331 _young_time(), 4332 _non_young_time(), 4333 _stats(stats) { } 4334 4335 virtual bool do_heap_region(HeapRegion* r) { 4336 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index()); 4337 JFREventForRegion event(r, _worker_id); 4338 TimerForRegion timer(timer_for_region(r)); 4339 4340 _g1h->clear_region_attr(r); 4341 stats()->account_rs_length(r); 4342 4343 if (r->is_young()) { 4344 assert_in_cset(r); 4345 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]); 4346 } 4347 4348 if (r->evacuation_failed()) { 4349 handle_failed_region(r); 4350 } else { 4351 handle_evacuated_region(r); 4352 } 4353 assert(!_g1h->is_on_master_free_list(r), "sanity"); 4354 4355 return false; 4356 } 4357 4358 void report_timing(Tickspan parallel_time) { 4359 G1GCPhaseTimes* pt = _g1h->phase_times(); 4360 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds()); 4361 if (_young_time.value() > 0) { 4362 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds()); 4363 } 4364 if (_non_young_time.value() > 0) { 4365 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds()); 4366 } 4367 } 4368 }; 4369 4370 // G1FreeCollectionSetTask members 4371 G1CollectedHeap* _g1h; 4372 G1EvacuationInfo* _evacuation_info; 4373 FreeCSetStats* _worker_stats; 4374 HeapRegionClaimer _claimer; 4375 const size_t* _surviving_young_words; 4376 uint _active_workers; 4377 4378 FreeCSetStats* worker_stats(uint worker) { 4379 return &_worker_stats[worker]; 4380 } 4381 4382 void report_statistics() { 4383 // Merge the accounting 4384 FreeCSetStats total_stats; 4385 for (uint worker = 0; worker < _active_workers; worker++) { 4386 total_stats.merge_stats(worker_stats(worker)); 4387 } 4388 total_stats.report(_g1h, _evacuation_info); 4389 } 4390 4391 public: 4392 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) : 4393 AbstractGangTask("G1 Free Collection Set"), 4394 _g1h(G1CollectedHeap::heap()), 4395 _evacuation_info(evacuation_info), 4396 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)), 4397 _claimer(active_workers), 4398 _surviving_young_words(surviving_young_words), 4399 _active_workers(active_workers) { 4400 for (uint worker = 0; worker < active_workers; worker++) { 4401 ::new (&_worker_stats[worker]) FreeCSetStats(); 4402 } 4403 } 4404 4405 ~G1FreeCollectionSetTask() { 4406 Ticks serial_time = Ticks::now(); 4407 report_statistics(); 4408 for (uint worker = 0; worker < _active_workers; worker++) { 4409 _worker_stats[worker].~FreeCSetStats(); 4410 } 4411 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats); 4412 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0); 4413 } 4414 4415 virtual void work(uint worker_id) { 4416 EventGCPhaseParallel event; 4417 Ticks start = Ticks::now(); 4418 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id)); 4419 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id); 4420 4421 // Report the total parallel time along with some more detailed metrics. 4422 cl.report_timing(Ticks::now() - start); 4423 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet)); 4424 } 4425 }; 4426 4427 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4428 _eden.clear(); 4429 4430 // The free collections set is split up in two tasks, the first 4431 // frees the collection set and records what regions are free, 4432 // and the second one rebuilds the free list. This proved to be 4433 // more efficient than adding a sorted list to another. 4434 4435 Ticks free_cset_start_time = Ticks::now(); 4436 { 4437 uint const num_cs_regions = _collection_set.region_length(); 4438 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers()); 4439 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers); 4440 4441 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)", 4442 cl.name(), num_workers, num_cs_regions, num_regions()); 4443 workers()->run_task(&cl, num_workers); 4444 } 4445 4446 Ticks free_cset_end_time = Ticks::now(); 4447 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0); 4448 4449 // Now rebuild the free region list. 4450 hrm()->rebuild_free_list(workers()); 4451 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0); 4452 4453 collection_set->clear(); 4454 } 4455 4456 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4457 private: 4458 FreeRegionList* _free_region_list; 4459 HeapRegionSet* _proxy_set; 4460 uint _humongous_objects_reclaimed; 4461 uint _humongous_regions_reclaimed; 4462 size_t _freed_bytes; 4463 public: 4464 4465 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4466 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4467 } 4468 4469 virtual bool do_heap_region(HeapRegion* r) { 4470 if (!r->is_starts_humongous()) { 4471 return false; 4472 } 4473 4474 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4475 4476 oop obj = (oop)r->bottom(); 4477 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4478 4479 // The following checks whether the humongous object is live are sufficient. 4480 // The main additional check (in addition to having a reference from the roots 4481 // or the young gen) is whether the humongous object has a remembered set entry. 4482 // 4483 // A humongous object cannot be live if there is no remembered set for it 4484 // because: 4485 // - there can be no references from within humongous starts regions referencing 4486 // the object because we never allocate other objects into them. 4487 // (I.e. there are no intra-region references that may be missed by the 4488 // remembered set) 4489 // - as soon there is a remembered set entry to the humongous starts region 4490 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4491 // until the end of a concurrent mark. 4492 // 4493 // It is not required to check whether the object has been found dead by marking 4494 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4495 // all objects allocated during that time are considered live. 4496 // SATB marking is even more conservative than the remembered set. 4497 // So if at this point in the collection there is no remembered set entry, 4498 // nobody has a reference to it. 4499 // At the start of collection we flush all refinement logs, and remembered sets 4500 // are completely up-to-date wrt to references to the humongous object. 4501 // 4502 // Other implementation considerations: 4503 // - never consider object arrays at this time because they would pose 4504 // considerable effort for cleaning up the the remembered sets. This is 4505 // required because stale remembered sets might reference locations that 4506 // are currently allocated into. 4507 uint region_idx = r->hrm_index(); 4508 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4509 !r->rem_set()->is_empty()) { 4510 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", 4511 region_idx, 4512 (size_t)obj->size() * HeapWordSize, 4513 p2i(r->bottom()), 4514 r->rem_set()->occupied(), 4515 r->rem_set()->strong_code_roots_list_length(), 4516 next_bitmap->is_marked(r->bottom()), 4517 g1h->is_humongous_reclaim_candidate(region_idx), 4518 obj->is_typeArray() 4519 ); 4520 return false; 4521 } 4522 4523 guarantee(obj->is_typeArray(), 4524 "Only eagerly reclaiming type arrays is supported, but the object " 4525 PTR_FORMAT " is not.", p2i(r->bottom())); 4526 4527 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", 4528 region_idx, 4529 (size_t)obj->size() * HeapWordSize, 4530 p2i(r->bottom()), 4531 r->rem_set()->occupied(), 4532 r->rem_set()->strong_code_roots_list_length(), 4533 next_bitmap->is_marked(r->bottom()), 4534 g1h->is_humongous_reclaim_candidate(region_idx), 4535 obj->is_typeArray() 4536 ); 4537 4538 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4539 cm->humongous_object_eagerly_reclaimed(r); 4540 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4541 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4542 region_idx, 4543 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4544 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4545 _humongous_objects_reclaimed++; 4546 do { 4547 HeapRegion* next = g1h->next_region_in_humongous(r); 4548 _freed_bytes += r->used(); 4549 r->set_containing_set(NULL); 4550 _humongous_regions_reclaimed++; 4551 g1h->free_humongous_region(r, _free_region_list); 4552 r = next; 4553 } while (r != NULL); 4554 4555 return false; 4556 } 4557 4558 uint humongous_objects_reclaimed() { 4559 return _humongous_objects_reclaimed; 4560 } 4561 4562 uint humongous_regions_reclaimed() { 4563 return _humongous_regions_reclaimed; 4564 } 4565 4566 size_t bytes_freed() const { 4567 return _freed_bytes; 4568 } 4569 }; 4570 4571 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4572 assert_at_safepoint_on_vm_thread(); 4573 4574 if (!G1EagerReclaimHumongousObjects || 4575 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4576 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4577 return; 4578 } 4579 4580 double start_time = os::elapsedTime(); 4581 4582 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4583 4584 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4585 heap_region_iterate(&cl); 4586 4587 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4588 4589 G1HRPrinter* hrp = hr_printer(); 4590 if (hrp->is_active()) { 4591 FreeRegionListIterator iter(&local_cleanup_list); 4592 while (iter.more_available()) { 4593 HeapRegion* hr = iter.get_next(); 4594 hrp->cleanup(hr); 4595 } 4596 } 4597 4598 prepend_to_freelist(&local_cleanup_list); 4599 decrement_summary_bytes(cl.bytes_freed()); 4600 4601 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4602 cl.humongous_objects_reclaimed()); 4603 } 4604 4605 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4606 public: 4607 virtual bool do_heap_region(HeapRegion* r) { 4608 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4609 G1CollectedHeap::heap()->clear_region_attr(r); 4610 r->clear_young_index_in_cset(); 4611 return false; 4612 } 4613 }; 4614 4615 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4616 G1AbandonCollectionSetClosure cl; 4617 collection_set_iterate_all(&cl); 4618 4619 collection_set->clear(); 4620 collection_set->stop_incremental_building(); 4621 } 4622 4623 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4624 return _allocator->is_retained_old_region(hr); 4625 } 4626 4627 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4628 _eden.add(hr); 4629 _policy->set_region_eden(hr); 4630 } 4631 4632 #ifdef ASSERT 4633 4634 class NoYoungRegionsClosure: public HeapRegionClosure { 4635 private: 4636 bool _success; 4637 public: 4638 NoYoungRegionsClosure() : _success(true) { } 4639 bool do_heap_region(HeapRegion* r) { 4640 if (r->is_young()) { 4641 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4642 p2i(r->bottom()), p2i(r->end())); 4643 _success = false; 4644 } 4645 return false; 4646 } 4647 bool success() { return _success; } 4648 }; 4649 4650 bool G1CollectedHeap::check_young_list_empty() { 4651 bool ret = (young_regions_count() == 0); 4652 4653 NoYoungRegionsClosure closure; 4654 heap_region_iterate(&closure); 4655 ret = ret && closure.success(); 4656 4657 return ret; 4658 } 4659 4660 #endif // ASSERT 4661 4662 class TearDownRegionSetsClosure : public HeapRegionClosure { 4663 HeapRegionSet *_old_set; 4664 4665 public: 4666 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4667 4668 bool do_heap_region(HeapRegion* r) { 4669 if (r->is_old()) { 4670 _old_set->remove(r); 4671 } else if(r->is_young()) { 4672 r->uninstall_surv_rate_group(); 4673 } else { 4674 // We ignore free regions, we'll empty the free list afterwards. 4675 // We ignore humongous and archive regions, we're not tearing down these 4676 // sets. 4677 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4678 "it cannot be another type"); 4679 } 4680 return false; 4681 } 4682 4683 ~TearDownRegionSetsClosure() { 4684 assert(_old_set->is_empty(), "post-condition"); 4685 } 4686 }; 4687 4688 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4689 assert_at_safepoint_on_vm_thread(); 4690 4691 if (!free_list_only) { 4692 TearDownRegionSetsClosure cl(&_old_set); 4693 heap_region_iterate(&cl); 4694 4695 // Note that emptying the _young_list is postponed and instead done as 4696 // the first step when rebuilding the regions sets again. The reason for 4697 // this is that during a full GC string deduplication needs to know if 4698 // a collected region was young or old when the full GC was initiated. 4699 } 4700 _hrm->remove_all_free_regions(); 4701 } 4702 4703 void G1CollectedHeap::increase_used(size_t bytes) { 4704 _summary_bytes_used += bytes; 4705 } 4706 4707 void G1CollectedHeap::decrease_used(size_t bytes) { 4708 assert(_summary_bytes_used >= bytes, 4709 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4710 _summary_bytes_used, bytes); 4711 _summary_bytes_used -= bytes; 4712 } 4713 4714 void G1CollectedHeap::set_used(size_t bytes) { 4715 _summary_bytes_used = bytes; 4716 } 4717 4718 class RebuildRegionSetsClosure : public HeapRegionClosure { 4719 private: 4720 bool _free_list_only; 4721 4722 HeapRegionSet* _old_set; 4723 HeapRegionManager* _hrm; 4724 4725 size_t _total_used; 4726 4727 public: 4728 RebuildRegionSetsClosure(bool free_list_only, 4729 HeapRegionSet* old_set, 4730 HeapRegionManager* hrm) : 4731 _free_list_only(free_list_only), 4732 _old_set(old_set), _hrm(hrm), _total_used(0) { 4733 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4734 if (!free_list_only) { 4735 assert(_old_set->is_empty(), "pre-condition"); 4736 } 4737 } 4738 4739 bool do_heap_region(HeapRegion* r) { 4740 if (r->is_empty()) { 4741 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4742 // Add free regions to the free list 4743 r->set_free(); 4744 _hrm->insert_into_free_list(r); 4745 } else if (!_free_list_only) { 4746 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4747 4748 if (r->is_archive() || r->is_humongous()) { 4749 // We ignore archive and humongous regions. We left these sets unchanged. 4750 } else { 4751 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4752 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4753 r->move_to_old(); 4754 _old_set->add(r); 4755 } 4756 _total_used += r->used(); 4757 } 4758 4759 return false; 4760 } 4761 4762 size_t total_used() { 4763 return _total_used; 4764 } 4765 }; 4766 4767 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4768 assert_at_safepoint_on_vm_thread(); 4769 4770 if (!free_list_only) { 4771 _eden.clear(); 4772 _survivor.clear(); 4773 } 4774 4775 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4776 heap_region_iterate(&cl); 4777 4778 if (!free_list_only) { 4779 set_used(cl.total_used()); 4780 if (_archive_allocator != NULL) { 4781 _archive_allocator->clear_used(); 4782 } 4783 } 4784 assert_used_and_recalculate_used_equal(this); 4785 } 4786 4787 // Methods for the mutator alloc region 4788 4789 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4790 bool force, 4791 uint node_index) { 4792 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4793 bool should_allocate = policy()->should_allocate_mutator_region(); 4794 if (force || should_allocate) { 4795 HeapRegion* new_alloc_region = new_region(word_size, 4796 HeapRegionType::Eden, 4797 false /* do_expand */, 4798 node_index); 4799 if (new_alloc_region != NULL) { 4800 set_region_short_lived_locked(new_alloc_region); 4801 _hr_printer.alloc(new_alloc_region, !should_allocate); 4802 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4803 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4804 return new_alloc_region; 4805 } 4806 } 4807 return NULL; 4808 } 4809 4810 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4811 size_t allocated_bytes) { 4812 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4813 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4814 4815 collection_set()->add_eden_region(alloc_region); 4816 increase_used(allocated_bytes); 4817 _eden.add_used_bytes(allocated_bytes); 4818 _hr_printer.retire(alloc_region); 4819 4820 // We update the eden sizes here, when the region is retired, 4821 // instead of when it's allocated, since this is the point that its 4822 // used space has been recorded in _summary_bytes_used. 4823 g1mm()->update_eden_size(); 4824 } 4825 4826 // Methods for the GC alloc regions 4827 4828 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4829 if (dest.is_old()) { 4830 return true; 4831 } else { 4832 return survivor_regions_count() < policy()->max_survivor_regions(); 4833 } 4834 } 4835 4836 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4837 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4838 4839 if (!has_more_regions(dest)) { 4840 return NULL; 4841 } 4842 4843 HeapRegionType type; 4844 if (dest.is_young()) { 4845 type = HeapRegionType::Survivor; 4846 } else { 4847 type = HeapRegionType::Old; 4848 } 4849 4850 HeapRegion* new_alloc_region = new_region(word_size, 4851 type, 4852 true /* do_expand */, 4853 node_index); 4854 4855 if (new_alloc_region != NULL) { 4856 if (type.is_survivor()) { 4857 new_alloc_region->set_survivor(); 4858 _survivor.add(new_alloc_region); 4859 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4860 } else { 4861 new_alloc_region->set_old(); 4862 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4863 } 4864 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4865 register_region_with_region_attr(new_alloc_region); 4866 _hr_printer.alloc(new_alloc_region); 4867 return new_alloc_region; 4868 } 4869 return NULL; 4870 } 4871 4872 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4873 size_t allocated_bytes, 4874 G1HeapRegionAttr dest) { 4875 _bytes_used_during_gc += allocated_bytes; 4876 if (dest.is_old()) { 4877 old_set_add(alloc_region); 4878 } else { 4879 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4880 _survivor.add_used_bytes(allocated_bytes); 4881 } 4882 4883 bool const during_im = collector_state()->in_initial_mark_gc(); 4884 if (during_im && allocated_bytes > 0) { 4885 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4886 } 4887 _hr_printer.retire(alloc_region); 4888 } 4889 4890 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4891 bool expanded = false; 4892 uint index = _hrm->find_highest_free(&expanded); 4893 4894 if (index != G1_NO_HRM_INDEX) { 4895 if (expanded) { 4896 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4897 HeapRegion::GrainWords * HeapWordSize); 4898 } 4899 _hrm->allocate_free_regions_starting_at(index, 1); 4900 return region_at(index); 4901 } 4902 return NULL; 4903 } 4904 4905 // Optimized nmethod scanning 4906 4907 class RegisterNMethodOopClosure: public OopClosure { 4908 G1CollectedHeap* _g1h; 4909 nmethod* _nm; 4910 4911 template <class T> void do_oop_work(T* p) { 4912 T heap_oop = RawAccess<>::oop_load(p); 4913 if (!CompressedOops::is_null(heap_oop)) { 4914 oop obj = CompressedOops::decode_not_null(heap_oop); 4915 HeapRegion* hr = _g1h->heap_region_containing(obj); 4916 assert(!hr->is_continues_humongous(), 4917 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4918 " starting at " HR_FORMAT, 4919 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4920 4921 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4922 hr->add_strong_code_root_locked(_nm); 4923 } 4924 } 4925 4926 public: 4927 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4928 _g1h(g1h), _nm(nm) {} 4929 4930 void do_oop(oop* p) { do_oop_work(p); } 4931 void do_oop(narrowOop* p) { do_oop_work(p); } 4932 }; 4933 4934 class UnregisterNMethodOopClosure: public OopClosure { 4935 G1CollectedHeap* _g1h; 4936 nmethod* _nm; 4937 4938 template <class T> void do_oop_work(T* p) { 4939 T heap_oop = RawAccess<>::oop_load(p); 4940 if (!CompressedOops::is_null(heap_oop)) { 4941 oop obj = CompressedOops::decode_not_null(heap_oop); 4942 HeapRegion* hr = _g1h->heap_region_containing(obj); 4943 assert(!hr->is_continues_humongous(), 4944 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4945 " starting at " HR_FORMAT, 4946 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4947 4948 hr->remove_strong_code_root(_nm); 4949 } 4950 } 4951 4952 public: 4953 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4954 _g1h(g1h), _nm(nm) {} 4955 4956 void do_oop(oop* p) { do_oop_work(p); } 4957 void do_oop(narrowOop* p) { do_oop_work(p); } 4958 }; 4959 4960 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4961 guarantee(nm != NULL, "sanity"); 4962 RegisterNMethodOopClosure reg_cl(this, nm); 4963 nm->oops_do(®_cl); 4964 } 4965 4966 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4967 guarantee(nm != NULL, "sanity"); 4968 UnregisterNMethodOopClosure reg_cl(this, nm); 4969 nm->oops_do(®_cl, true); 4970 } 4971 4972 void G1CollectedHeap::purge_code_root_memory() { 4973 double purge_start = os::elapsedTime(); 4974 G1CodeRootSet::purge(); 4975 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4976 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4977 } 4978 4979 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4980 G1CollectedHeap* _g1h; 4981 4982 public: 4983 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4984 _g1h(g1h) {} 4985 4986 void do_code_blob(CodeBlob* cb) { 4987 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4988 if (nm == NULL) { 4989 return; 4990 } 4991 4992 _g1h->register_nmethod(nm); 4993 } 4994 }; 4995 4996 void G1CollectedHeap::rebuild_strong_code_roots() { 4997 RebuildStrongCodeRootClosure blob_cl(this); 4998 CodeCache::blobs_do(&blob_cl); 4999 } 5000 5001 void G1CollectedHeap::initialize_serviceability() { 5002 _g1mm->initialize_serviceability(); 5003 } 5004 5005 MemoryUsage G1CollectedHeap::memory_usage() { 5006 return _g1mm->memory_usage(); 5007 } 5008 5009 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 5010 return _g1mm->memory_managers(); 5011 } 5012 5013 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 5014 return _g1mm->memory_pools(); 5015 }