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