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