1 /* 2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/g1Allocator.inline.hpp" 32 #include "gc/g1/g1Arguments.hpp" 33 #include "gc/g1/g1BarrierSet.hpp" 34 #include "gc/g1/g1CardTableEntryClosure.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectionSet.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 41 #include "gc/g1/g1DirtyCardQueue.hpp" 42 #include "gc/g1/g1EvacStats.inline.hpp" 43 #include "gc/g1/g1FullCollector.hpp" 44 #include "gc/g1/g1GCPhaseTimes.hpp" 45 #include "gc/g1/g1HeapSizingPolicy.hpp" 46 #include "gc/g1/g1HeapTransition.hpp" 47 #include "gc/g1/g1HeapVerifier.hpp" 48 #include "gc/g1/g1HotCardCache.hpp" 49 #include "gc/g1/g1MemoryPool.hpp" 50 #include "gc/g1/g1OopClosures.inline.hpp" 51 #include "gc/g1/g1ParallelCleaning.hpp" 52 #include "gc/g1/g1ParScanThreadState.inline.hpp" 53 #include "gc/g1/g1Policy.hpp" 54 #include "gc/g1/g1RedirtyCardsQueue.hpp" 55 #include "gc/g1/g1RegionToSpaceMapper.hpp" 56 #include "gc/g1/g1RemSet.hpp" 57 #include "gc/g1/g1RootClosures.hpp" 58 #include "gc/g1/g1RootProcessor.hpp" 59 #include "gc/g1/g1SATBMarkQueueSet.hpp" 60 #include "gc/g1/g1StringDedup.hpp" 61 #include "gc/g1/g1ThreadLocalData.hpp" 62 #include "gc/g1/g1Trace.hpp" 63 #include "gc/g1/g1YCTypes.hpp" 64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 65 #include "gc/g1/g1VMOperations.hpp" 66 #include "gc/g1/heapRegion.inline.hpp" 67 #include "gc/g1/heapRegionRemSet.hpp" 68 #include "gc/g1/heapRegionSet.inline.hpp" 69 #include "gc/shared/gcBehaviours.hpp" 70 #include "gc/shared/gcHeapSummary.hpp" 71 #include "gc/shared/gcId.hpp" 72 #include "gc/shared/gcLocker.hpp" 73 #include "gc/shared/gcTimer.hpp" 74 #include "gc/shared/gcTraceTime.inline.hpp" 75 #include "gc/shared/generationSpec.hpp" 76 #include "gc/shared/isGCActiveMark.hpp" 77 #include "gc/shared/locationPrinter.inline.hpp" 78 #include "gc/shared/oopStorageParState.hpp" 79 #include "gc/shared/preservedMarks.inline.hpp" 80 #include "gc/shared/suspendibleThreadSet.hpp" 81 #include "gc/shared/referenceProcessor.inline.hpp" 82 #include "gc/shared/taskqueue.inline.hpp" 83 #include "gc/shared/weakProcessor.inline.hpp" 84 #include "gc/shared/workerPolicy.hpp" 85 #include "logging/log.hpp" 86 #include "memory/allocation.hpp" 87 #include "memory/iterator.hpp" 88 #include "memory/resourceArea.hpp" 89 #include "memory/universe.hpp" 90 #include "oops/access.inline.hpp" 91 #include "oops/compressedOops.inline.hpp" 92 #include "oops/oop.inline.hpp" 93 #include "runtime/atomic.hpp" 94 #include "runtime/flags/flagSetting.hpp" 95 #include "runtime/handles.inline.hpp" 96 #include "runtime/init.hpp" 97 #include "runtime/orderAccess.hpp" 98 #include "runtime/threadSMR.hpp" 99 #include "runtime/vmThread.hpp" 100 #include "utilities/align.hpp" 101 #include "utilities/globalDefinitions.hpp" 102 #include "utilities/stack.inline.hpp" 103 104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 105 106 // INVARIANTS/NOTES 107 // 108 // All allocation activity covered by the G1CollectedHeap interface is 109 // serialized by acquiring the HeapLock. This happens in mem_allocate 110 // and allocate_new_tlab, which are the "entry" points to the 111 // allocation code from the rest of the JVM. (Note that this does not 112 // apply to TLAB allocation, which is not part of this interface: it 113 // is done by clients of this interface.) 114 115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 116 private: 117 size_t _num_dirtied; 118 G1CollectedHeap* _g1h; 119 G1CardTable* _g1_ct; 120 121 HeapRegion* region_for_card(CardValue* card_ptr) const { 122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 123 } 124 125 bool will_become_free(HeapRegion* hr) const { 126 // A region will be freed by free_collection_set if the region is in the 127 // collection set and has not had an evacuation failure. 128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 129 } 130 131 public: 132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 134 135 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 136 HeapRegion* hr = region_for_card(card_ptr); 137 138 // Should only dirty cards in regions that won't be freed. 139 if (!will_become_free(hr)) { 140 *card_ptr = G1CardTable::dirty_card_val(); 141 _num_dirtied++; 142 } 143 } 144 145 size_t num_dirtied() const { return _num_dirtied; } 146 }; 147 148 149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 151 } 152 153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 154 // The from card cache is not the memory that is actually committed. So we cannot 155 // take advantage of the zero_filled parameter. 156 reset_from_card_cache(start_idx, num_regions); 157 } 158 159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 160 Ticks start = Ticks::now(); 161 workers()->run_task(task, workers()->active_workers()); 162 return Ticks::now() - start; 163 } 164 165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 166 MemRegion mr) { 167 return new HeapRegion(hrs_index, bot(), mr); 168 } 169 170 // Private methods. 171 172 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 173 HeapRegionType type, 174 bool do_expand, 175 uint node_index) { 176 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 177 "the only time we use this to allocate a humongous region is " 178 "when we are allocating a single humongous region"); 179 180 HeapRegion* res = _hrm->allocate_free_region(type, node_index); 181 182 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 183 // Currently, only attempts to allocate GC alloc regions set 184 // do_expand to true. So, we should only reach here during a 185 // safepoint. If this assumption changes we might have to 186 // reconsider the use of _expand_heap_after_alloc_failure. 187 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 188 189 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 190 word_size * HeapWordSize); 191 192 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 193 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 194 word_size * HeapWordSize); 195 if (expand_single_region(node_index)) { 196 // Given that expand_single_region() succeeded in expanding the heap, and we 197 // always expand the heap by an amount aligned to the heap 198 // region size, the free list should in theory not be empty. 199 // In either case allocate_free_region() will check for NULL. 200 res = _hrm->allocate_free_region(type, node_index); 201 } else { 202 _expand_heap_after_alloc_failure = false; 203 } 204 } 205 return res; 206 } 207 208 HeapWord* 209 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 210 uint num_regions, 211 size_t word_size) { 212 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 213 assert(is_humongous(word_size), "word_size should be humongous"); 214 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 215 216 // Index of last region in the series. 217 uint last = first + num_regions - 1; 218 219 // We need to initialize the region(s) we just discovered. This is 220 // a bit tricky given that it can happen concurrently with 221 // refinement threads refining cards on these regions and 222 // potentially wanting to refine the BOT as they are scanning 223 // those cards (this can happen shortly after a cleanup; see CR 224 // 6991377). So we have to set up the region(s) carefully and in 225 // a specific order. 226 227 // The word size sum of all the regions we will allocate. 228 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 229 assert(word_size <= word_size_sum, "sanity"); 230 231 // This will be the "starts humongous" region. 232 HeapRegion* first_hr = region_at(first); 233 // The header of the new object will be placed at the bottom of 234 // the first region. 235 HeapWord* new_obj = first_hr->bottom(); 236 // This will be the new top of the new object. 237 HeapWord* obj_top = new_obj + word_size; 238 239 // First, we need to zero the header of the space that we will be 240 // allocating. When we update top further down, some refinement 241 // threads might try to scan the region. By zeroing the header we 242 // ensure that any thread that will try to scan the region will 243 // come across the zero klass word and bail out. 244 // 245 // NOTE: It would not have been correct to have used 246 // CollectedHeap::fill_with_object() and make the space look like 247 // an int array. The thread that is doing the allocation will 248 // later update the object header to a potentially different array 249 // type and, for a very short period of time, the klass and length 250 // fields will be inconsistent. This could cause a refinement 251 // thread to calculate the object size incorrectly. 252 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 253 254 // Next, pad out the unused tail of the last region with filler 255 // objects, for improved usage accounting. 256 // How many words we use for filler objects. 257 size_t word_fill_size = word_size_sum - word_size; 258 259 // How many words memory we "waste" which cannot hold a filler object. 260 size_t words_not_fillable = 0; 261 262 if (word_fill_size >= min_fill_size()) { 263 fill_with_objects(obj_top, word_fill_size); 264 } else if (word_fill_size > 0) { 265 // We have space to fill, but we cannot fit an object there. 266 words_not_fillable = word_fill_size; 267 word_fill_size = 0; 268 } 269 270 // We will set up the first region as "starts humongous". This 271 // will also update the BOT covering all the regions to reflect 272 // that there is a single object that starts at the bottom of the 273 // first region. 274 first_hr->set_starts_humongous(obj_top, word_fill_size); 275 _policy->remset_tracker()->update_at_allocate(first_hr); 276 // Then, if there are any, we will set up the "continues 277 // humongous" regions. 278 HeapRegion* hr = NULL; 279 for (uint i = first + 1; i <= last; ++i) { 280 hr = region_at(i); 281 hr->set_continues_humongous(first_hr); 282 _policy->remset_tracker()->update_at_allocate(hr); 283 } 284 285 // Up to this point no concurrent thread would have been able to 286 // do any scanning on any region in this series. All the top 287 // fields still point to bottom, so the intersection between 288 // [bottom,top] and [card_start,card_end] will be empty. Before we 289 // update the top fields, we'll do a storestore to make sure that 290 // no thread sees the update to top before the zeroing of the 291 // object header and the BOT initialization. 292 OrderAccess::storestore(); 293 294 // Now, we will update the top fields of the "continues humongous" 295 // regions except the last one. 296 for (uint i = first; i < last; ++i) { 297 hr = region_at(i); 298 hr->set_top(hr->end()); 299 } 300 301 hr = region_at(last); 302 // If we cannot fit a filler object, we must set top to the end 303 // of the humongous object, otherwise we cannot iterate the heap 304 // and the BOT will not be complete. 305 hr->set_top(hr->end() - words_not_fillable); 306 307 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 308 "obj_top should be in last region"); 309 310 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 311 312 assert(words_not_fillable == 0 || 313 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 314 "Miscalculation in humongous allocation"); 315 316 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 317 318 for (uint i = first; i <= last; ++i) { 319 hr = region_at(i); 320 _humongous_set.add(hr); 321 _hr_printer.alloc(hr); 322 } 323 324 return new_obj; 325 } 326 327 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 328 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 329 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 330 } 331 332 // If could fit into free regions w/o expansion, try. 333 // Otherwise, if can expand, do so. 334 // Otherwise, if using ex regions might help, try with ex given back. 335 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 336 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 337 338 _verifier->verify_region_sets_optional(); 339 340 uint first = G1_NO_HRM_INDEX; 341 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 342 343 if (obj_regions == 1) { 344 // Only one region to allocate, try to use a fast path by directly allocating 345 // from the free lists. Do not try to expand here, we will potentially do that 346 // later. 347 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 348 if (hr != NULL) { 349 first = hr->hrm_index(); 350 } 351 } else { 352 // Policy: Try only empty regions (i.e. already committed first). Maybe we 353 // are lucky enough to find some. 354 first = _hrm->find_contiguous_only_empty(obj_regions); 355 if (first != G1_NO_HRM_INDEX) { 356 _hrm->allocate_free_regions_starting_at(first, obj_regions); 357 } 358 } 359 360 if (first == G1_NO_HRM_INDEX) { 361 // Policy: We could not find enough regions for the humongous object in the 362 // free list. Look through the heap to find a mix of free and uncommitted regions. 363 // If so, try expansion. 364 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 365 if (first != G1_NO_HRM_INDEX) { 366 // We found something. Make sure these regions are committed, i.e. expand 367 // the heap. Alternatively we could do a defragmentation GC. 368 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 369 word_size * HeapWordSize); 370 371 _hrm->expand_at(first, obj_regions, workers()); 372 policy()->record_new_heap_size(num_regions()); 373 374 #ifdef ASSERT 375 for (uint i = first; i < first + obj_regions; ++i) { 376 HeapRegion* hr = region_at(i); 377 assert(hr->is_free(), "sanity"); 378 assert(hr->is_empty(), "sanity"); 379 assert(is_on_master_free_list(hr), "sanity"); 380 } 381 #endif 382 _hrm->allocate_free_regions_starting_at(first, obj_regions); 383 } else { 384 // Policy: Potentially trigger a defragmentation GC. 385 } 386 } 387 388 HeapWord* result = NULL; 389 if (first != G1_NO_HRM_INDEX) { 390 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 391 assert(result != NULL, "it should always return a valid result"); 392 393 // A successful humongous object allocation changes the used space 394 // information of the old generation so we need to recalculate the 395 // sizes and update the jstat counters here. 396 g1mm()->update_sizes(); 397 } 398 399 _verifier->verify_region_sets_optional(); 400 401 return result; 402 } 403 404 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 405 size_t requested_size, 406 size_t* actual_size) { 407 assert_heap_not_locked_and_not_at_safepoint(); 408 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 409 410 return attempt_allocation(min_size, requested_size, actual_size); 411 } 412 413 HeapWord* 414 G1CollectedHeap::mem_allocate(size_t word_size, 415 bool* gc_overhead_limit_was_exceeded) { 416 assert_heap_not_locked_and_not_at_safepoint(); 417 418 if (is_humongous(word_size)) { 419 return attempt_allocation_humongous(word_size); 420 } 421 size_t dummy = 0; 422 return attempt_allocation(word_size, word_size, &dummy); 423 } 424 425 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 426 ResourceMark rm; // For retrieving the thread names in log messages. 427 428 // Make sure you read the note in attempt_allocation_humongous(). 429 430 assert_heap_not_locked_and_not_at_safepoint(); 431 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 432 "be called for humongous allocation requests"); 433 434 // We should only get here after the first-level allocation attempt 435 // (attempt_allocation()) failed to allocate. 436 437 // We will loop until a) we manage to successfully perform the 438 // allocation or b) we successfully schedule a collection which 439 // fails to perform the allocation. b) is the only case when we'll 440 // return NULL. 441 HeapWord* result = NULL; 442 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 443 bool should_try_gc; 444 uint gc_count_before; 445 446 { 447 MutexLocker x(Heap_lock); 448 result = _allocator->attempt_allocation_locked(word_size); 449 if (result != NULL) { 450 return result; 451 } 452 453 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 454 // This is different to when only GCLocker::needs_gc() is set: try to avoid 455 // waiting because the GCLocker is active to not wait too long. 456 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 457 // No need for an ergo message here, can_expand_young_list() does this when 458 // it returns true. 459 result = _allocator->attempt_allocation_force(word_size); 460 if (result != NULL) { 461 return result; 462 } 463 } 464 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 465 // the GCLocker initiated GC has been performed and then retry. This includes 466 // the case when the GC Locker is not active but has not been performed. 467 should_try_gc = !GCLocker::needs_gc(); 468 // Read the GC count while still holding the Heap_lock. 469 gc_count_before = total_collections(); 470 } 471 472 if (should_try_gc) { 473 bool succeeded; 474 result = do_collection_pause(word_size, gc_count_before, &succeeded, 475 GCCause::_g1_inc_collection_pause); 476 if (result != NULL) { 477 assert(succeeded, "only way to get back a non-NULL result"); 478 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 479 Thread::current()->name(), p2i(result)); 480 return result; 481 } 482 483 if (succeeded) { 484 // We successfully scheduled a collection which failed to allocate. No 485 // point in trying to allocate further. We'll just return NULL. 486 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 487 SIZE_FORMAT " words", Thread::current()->name(), word_size); 488 return NULL; 489 } 490 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 491 Thread::current()->name(), word_size); 492 } else { 493 // Failed to schedule a collection. 494 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 495 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 496 SIZE_FORMAT " words", Thread::current()->name(), word_size); 497 return NULL; 498 } 499 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 500 // The GCLocker is either active or the GCLocker initiated 501 // GC has not yet been performed. Stall until it is and 502 // then retry the allocation. 503 GCLocker::stall_until_clear(); 504 gclocker_retry_count += 1; 505 } 506 507 // We can reach here if we were unsuccessful in scheduling a 508 // collection (because another thread beat us to it) or if we were 509 // stalled due to the GC locker. In either can we should retry the 510 // allocation attempt in case another thread successfully 511 // performed a collection and reclaimed enough space. We do the 512 // first attempt (without holding the Heap_lock) here and the 513 // follow-on attempt will be at the start of the next loop 514 // iteration (after taking the Heap_lock). 515 size_t dummy = 0; 516 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 517 if (result != NULL) { 518 return result; 519 } 520 521 // Give a warning if we seem to be looping forever. 522 if ((QueuedAllocationWarningCount > 0) && 523 (try_count % QueuedAllocationWarningCount == 0)) { 524 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 525 Thread::current()->name(), try_count, word_size); 526 } 527 } 528 529 ShouldNotReachHere(); 530 return NULL; 531 } 532 533 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 534 assert_at_safepoint_on_vm_thread(); 535 if (_archive_allocator == NULL) { 536 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 537 } 538 } 539 540 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 541 // Allocations in archive regions cannot be of a size that would be considered 542 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 543 // may be different at archive-restore time. 544 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 545 } 546 547 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 548 assert_at_safepoint_on_vm_thread(); 549 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 550 if (is_archive_alloc_too_large(word_size)) { 551 return NULL; 552 } 553 return _archive_allocator->archive_mem_allocate(word_size); 554 } 555 556 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 557 size_t end_alignment_in_bytes) { 558 assert_at_safepoint_on_vm_thread(); 559 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 560 561 // Call complete_archive to do the real work, filling in the MemRegion 562 // array with the archive regions. 563 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 564 delete _archive_allocator; 565 _archive_allocator = NULL; 566 } 567 568 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 569 assert(ranges != NULL, "MemRegion array NULL"); 570 assert(count != 0, "No MemRegions provided"); 571 MemRegion reserved = _hrm->reserved(); 572 for (size_t i = 0; i < count; i++) { 573 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 574 return false; 575 } 576 } 577 return true; 578 } 579 580 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 581 size_t count, 582 bool open) { 583 assert(!is_init_completed(), "Expect to be called at JVM init time"); 584 assert(ranges != NULL, "MemRegion array NULL"); 585 assert(count != 0, "No MemRegions provided"); 586 MutexLocker x(Heap_lock); 587 588 MemRegion reserved = _hrm->reserved(); 589 HeapWord* prev_last_addr = NULL; 590 HeapRegion* prev_last_region = NULL; 591 592 // Temporarily disable pretouching of heap pages. This interface is used 593 // when mmap'ing archived heap data in, so pre-touching is wasted. 594 FlagSetting fs(AlwaysPreTouch, false); 595 596 // Enable archive object checking used by G1MarkSweep. We have to let it know 597 // about each archive range, so that objects in those ranges aren't marked. 598 G1ArchiveAllocator::enable_archive_object_check(); 599 600 // For each specified MemRegion range, allocate the corresponding G1 601 // regions and mark them as archive regions. We expect the ranges 602 // in ascending starting address order, without overlap. 603 for (size_t i = 0; i < count; i++) { 604 MemRegion curr_range = ranges[i]; 605 HeapWord* start_address = curr_range.start(); 606 size_t word_size = curr_range.word_size(); 607 HeapWord* last_address = curr_range.last(); 608 size_t commits = 0; 609 610 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 611 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 612 p2i(start_address), p2i(last_address)); 613 guarantee(start_address > prev_last_addr, 614 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 615 p2i(start_address), p2i(prev_last_addr)); 616 prev_last_addr = last_address; 617 618 // Check for ranges that start in the same G1 region in which the previous 619 // range ended, and adjust the start address so we don't try to allocate 620 // the same region again. If the current range is entirely within that 621 // region, skip it, just adjusting the recorded top. 622 HeapRegion* start_region = _hrm->addr_to_region(start_address); 623 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 624 start_address = start_region->end(); 625 if (start_address > last_address) { 626 increase_used(word_size * HeapWordSize); 627 start_region->set_top(last_address + 1); 628 continue; 629 } 630 start_region->set_top(start_address); 631 curr_range = MemRegion(start_address, last_address + 1); 632 start_region = _hrm->addr_to_region(start_address); 633 } 634 635 // Perform the actual region allocation, exiting if it fails. 636 // Then note how much new space we have allocated. 637 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 638 return false; 639 } 640 increase_used(word_size * HeapWordSize); 641 if (commits != 0) { 642 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 643 HeapRegion::GrainWords * HeapWordSize * commits); 644 645 } 646 647 // Mark each G1 region touched by the range as archive, add it to 648 // the old set, and set top. 649 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 650 HeapRegion* last_region = _hrm->addr_to_region(last_address); 651 prev_last_region = last_region; 652 653 while (curr_region != NULL) { 654 assert(curr_region->is_empty() && !curr_region->is_pinned(), 655 "Region already in use (index %u)", curr_region->hrm_index()); 656 if (open) { 657 curr_region->set_open_archive(); 658 } else { 659 curr_region->set_closed_archive(); 660 } 661 _hr_printer.alloc(curr_region); 662 _archive_set.add(curr_region); 663 HeapWord* top; 664 HeapRegion* next_region; 665 if (curr_region != last_region) { 666 top = curr_region->end(); 667 next_region = _hrm->next_region_in_heap(curr_region); 668 } else { 669 top = last_address + 1; 670 next_region = NULL; 671 } 672 curr_region->set_top(top); 673 curr_region = next_region; 674 } 675 676 // Notify mark-sweep of the archive 677 G1ArchiveAllocator::set_range_archive(curr_range, open); 678 } 679 return true; 680 } 681 682 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 683 assert(!is_init_completed(), "Expect to be called at JVM init time"); 684 assert(ranges != NULL, "MemRegion array NULL"); 685 assert(count != 0, "No MemRegions provided"); 686 MemRegion reserved = _hrm->reserved(); 687 HeapWord *prev_last_addr = NULL; 688 HeapRegion* prev_last_region = NULL; 689 690 // For each MemRegion, create filler objects, if needed, in the G1 regions 691 // that contain the address range. The address range actually within the 692 // MemRegion will not be modified. That is assumed to have been initialized 693 // elsewhere, probably via an mmap of archived heap data. 694 MutexLocker x(Heap_lock); 695 for (size_t i = 0; i < count; i++) { 696 HeapWord* start_address = ranges[i].start(); 697 HeapWord* last_address = ranges[i].last(); 698 699 assert(reserved.contains(start_address) && reserved.contains(last_address), 700 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 701 p2i(start_address), p2i(last_address)); 702 assert(start_address > prev_last_addr, 703 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 704 p2i(start_address), p2i(prev_last_addr)); 705 706 HeapRegion* start_region = _hrm->addr_to_region(start_address); 707 HeapRegion* last_region = _hrm->addr_to_region(last_address); 708 HeapWord* bottom_address = start_region->bottom(); 709 710 // Check for a range beginning in the same region in which the 711 // previous one ended. 712 if (start_region == prev_last_region) { 713 bottom_address = prev_last_addr + 1; 714 } 715 716 // Verify that the regions were all marked as archive regions by 717 // alloc_archive_regions. 718 HeapRegion* curr_region = start_region; 719 while (curr_region != NULL) { 720 guarantee(curr_region->is_archive(), 721 "Expected archive region at index %u", curr_region->hrm_index()); 722 if (curr_region != last_region) { 723 curr_region = _hrm->next_region_in_heap(curr_region); 724 } else { 725 curr_region = NULL; 726 } 727 } 728 729 prev_last_addr = last_address; 730 prev_last_region = last_region; 731 732 // Fill the memory below the allocated range with dummy object(s), 733 // if the region bottom does not match the range start, or if the previous 734 // range ended within the same G1 region, and there is a gap. 735 if (start_address != bottom_address) { 736 size_t fill_size = pointer_delta(start_address, bottom_address); 737 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 738 increase_used(fill_size * HeapWordSize); 739 } 740 } 741 } 742 743 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 744 size_t desired_word_size, 745 size_t* actual_word_size) { 746 assert_heap_not_locked_and_not_at_safepoint(); 747 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 748 "be called for humongous allocation requests"); 749 750 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 751 752 if (result == NULL) { 753 *actual_word_size = desired_word_size; 754 result = attempt_allocation_slow(desired_word_size); 755 } 756 757 assert_heap_not_locked(); 758 if (result != NULL) { 759 assert(*actual_word_size != 0, "Actual size must have been set here"); 760 dirty_young_block(result, *actual_word_size); 761 } else { 762 *actual_word_size = 0; 763 } 764 765 return result; 766 } 767 768 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 769 assert(!is_init_completed(), "Expect to be called at JVM init time"); 770 assert(ranges != NULL, "MemRegion array NULL"); 771 assert(count != 0, "No MemRegions provided"); 772 MemRegion reserved = _hrm->reserved(); 773 HeapWord* prev_last_addr = NULL; 774 HeapRegion* prev_last_region = NULL; 775 size_t size_used = 0; 776 size_t uncommitted_regions = 0; 777 778 // For each Memregion, free the G1 regions that constitute it, and 779 // notify mark-sweep that the range is no longer to be considered 'archive.' 780 MutexLocker x(Heap_lock); 781 for (size_t i = 0; i < count; i++) { 782 HeapWord* start_address = ranges[i].start(); 783 HeapWord* last_address = ranges[i].last(); 784 785 assert(reserved.contains(start_address) && reserved.contains(last_address), 786 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 787 p2i(start_address), p2i(last_address)); 788 assert(start_address > prev_last_addr, 789 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 790 p2i(start_address), p2i(prev_last_addr)); 791 size_used += ranges[i].byte_size(); 792 prev_last_addr = last_address; 793 794 HeapRegion* start_region = _hrm->addr_to_region(start_address); 795 HeapRegion* last_region = _hrm->addr_to_region(last_address); 796 797 // Check for ranges that start in the same G1 region in which the previous 798 // range ended, and adjust the start address so we don't try to free 799 // the same region again. If the current range is entirely within that 800 // region, skip it. 801 if (start_region == prev_last_region) { 802 start_address = start_region->end(); 803 if (start_address > last_address) { 804 continue; 805 } 806 start_region = _hrm->addr_to_region(start_address); 807 } 808 prev_last_region = last_region; 809 810 // After verifying that each region was marked as an archive region by 811 // alloc_archive_regions, set it free and empty and uncommit it. 812 HeapRegion* curr_region = start_region; 813 while (curr_region != NULL) { 814 guarantee(curr_region->is_archive(), 815 "Expected archive region at index %u", curr_region->hrm_index()); 816 uint curr_index = curr_region->hrm_index(); 817 _archive_set.remove(curr_region); 818 curr_region->set_free(); 819 curr_region->set_top(curr_region->bottom()); 820 if (curr_region != last_region) { 821 curr_region = _hrm->next_region_in_heap(curr_region); 822 } else { 823 curr_region = NULL; 824 } 825 _hrm->shrink_at(curr_index, 1); 826 uncommitted_regions++; 827 } 828 829 // Notify mark-sweep that this is no longer an archive range. 830 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 831 } 832 833 if (uncommitted_regions != 0) { 834 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 835 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 836 } 837 decrease_used(size_used); 838 } 839 840 oop G1CollectedHeap::materialize_archived_object(oop obj) { 841 assert(obj != NULL, "archived obj is NULL"); 842 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 843 844 // Loading an archived object makes it strongly reachable. If it is 845 // loaded during concurrent marking, it must be enqueued to the SATB 846 // queue, shading the previously white object gray. 847 G1BarrierSet::enqueue(obj); 848 849 return obj; 850 } 851 852 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 853 ResourceMark rm; // For retrieving the thread names in log messages. 854 855 // The structure of this method has a lot of similarities to 856 // attempt_allocation_slow(). The reason these two were not merged 857 // into a single one is that such a method would require several "if 858 // allocation is not humongous do this, otherwise do that" 859 // conditional paths which would obscure its flow. In fact, an early 860 // version of this code did use a unified method which was harder to 861 // follow and, as a result, it had subtle bugs that were hard to 862 // track down. So keeping these two methods separate allows each to 863 // be more readable. It will be good to keep these two in sync as 864 // much as possible. 865 866 assert_heap_not_locked_and_not_at_safepoint(); 867 assert(is_humongous(word_size), "attempt_allocation_humongous() " 868 "should only be called for humongous allocations"); 869 870 // Humongous objects can exhaust the heap quickly, so we should check if we 871 // need to start a marking cycle at each humongous object allocation. We do 872 // the check before we do the actual allocation. The reason for doing it 873 // before the allocation is that we avoid having to keep track of the newly 874 // allocated memory while we do a GC. 875 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 876 word_size)) { 877 collect(GCCause::_g1_humongous_allocation); 878 } 879 880 // We will loop until a) we manage to successfully perform the 881 // allocation or b) we successfully schedule a collection which 882 // fails to perform the allocation. b) is the only case when we'll 883 // return NULL. 884 HeapWord* result = NULL; 885 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 886 bool should_try_gc; 887 uint gc_count_before; 888 889 890 { 891 MutexLocker x(Heap_lock); 892 893 // Given that humongous objects are not allocated in young 894 // regions, we'll first try to do the allocation without doing a 895 // collection hoping that there's enough space in the heap. 896 result = humongous_obj_allocate(word_size); 897 if (result != NULL) { 898 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 899 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 900 return result; 901 } 902 903 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 904 // the GCLocker initiated GC has been performed and then retry. This includes 905 // the case when the GC Locker is not active but has not been performed. 906 should_try_gc = !GCLocker::needs_gc(); 907 // Read the GC count while still holding the Heap_lock. 908 gc_count_before = total_collections(); 909 } 910 911 if (should_try_gc) { 912 bool succeeded; 913 result = do_collection_pause(word_size, gc_count_before, &succeeded, 914 GCCause::_g1_humongous_allocation); 915 if (result != NULL) { 916 assert(succeeded, "only way to get back a non-NULL result"); 917 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 918 Thread::current()->name(), p2i(result)); 919 return result; 920 } 921 922 if (succeeded) { 923 // We successfully scheduled a collection which failed to allocate. No 924 // point in trying to allocate further. We'll just return NULL. 925 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 926 SIZE_FORMAT " words", Thread::current()->name(), word_size); 927 return NULL; 928 } 929 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 930 Thread::current()->name(), word_size); 931 } else { 932 // Failed to schedule a collection. 933 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 934 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 935 SIZE_FORMAT " words", Thread::current()->name(), word_size); 936 return NULL; 937 } 938 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 939 // The GCLocker is either active or the GCLocker initiated 940 // GC has not yet been performed. Stall until it is and 941 // then retry the allocation. 942 GCLocker::stall_until_clear(); 943 gclocker_retry_count += 1; 944 } 945 946 947 // We can reach here if we were unsuccessful in scheduling a 948 // collection (because another thread beat us to it) or if we were 949 // stalled due to the GC locker. In either can we should retry the 950 // allocation attempt in case another thread successfully 951 // performed a collection and reclaimed enough space. 952 // Humongous object allocation always needs a lock, so we wait for the retry 953 // in the next iteration of the loop, unlike for the regular iteration case. 954 // Give a warning if we seem to be looping forever. 955 956 if ((QueuedAllocationWarningCount > 0) && 957 (try_count % QueuedAllocationWarningCount == 0)) { 958 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 959 Thread::current()->name(), try_count, word_size); 960 } 961 } 962 963 ShouldNotReachHere(); 964 return NULL; 965 } 966 967 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 968 bool expect_null_mutator_alloc_region) { 969 assert_at_safepoint_on_vm_thread(); 970 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 971 "the current alloc region was unexpectedly found to be non-NULL"); 972 973 if (!is_humongous(word_size)) { 974 return _allocator->attempt_allocation_locked(word_size); 975 } else { 976 HeapWord* result = humongous_obj_allocate(word_size); 977 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 978 collector_state()->set_initiate_conc_mark_if_possible(true); 979 } 980 return result; 981 } 982 983 ShouldNotReachHere(); 984 } 985 986 class PostCompactionPrinterClosure: public HeapRegionClosure { 987 private: 988 G1HRPrinter* _hr_printer; 989 public: 990 bool do_heap_region(HeapRegion* hr) { 991 assert(!hr->is_young(), "not expecting to find young regions"); 992 _hr_printer->post_compaction(hr); 993 return false; 994 } 995 996 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 997 : _hr_printer(hr_printer) { } 998 }; 999 1000 void G1CollectedHeap::print_hrm_post_compaction() { 1001 if (_hr_printer.is_active()) { 1002 PostCompactionPrinterClosure cl(hr_printer()); 1003 heap_region_iterate(&cl); 1004 } 1005 } 1006 1007 void G1CollectedHeap::abort_concurrent_cycle() { 1008 // If we start the compaction before the CM threads finish 1009 // scanning the root regions we might trip them over as we'll 1010 // be moving objects / updating references. So let's wait until 1011 // they are done. By telling them to abort, they should complete 1012 // early. 1013 _cm->root_regions()->abort(); 1014 _cm->root_regions()->wait_until_scan_finished(); 1015 1016 // Disable discovery and empty the discovered lists 1017 // for the CM ref processor. 1018 _ref_processor_cm->disable_discovery(); 1019 _ref_processor_cm->abandon_partial_discovery(); 1020 _ref_processor_cm->verify_no_references_recorded(); 1021 1022 // Abandon current iterations of concurrent marking and concurrent 1023 // refinement, if any are in progress. 1024 concurrent_mark()->concurrent_cycle_abort(); 1025 } 1026 1027 void G1CollectedHeap::prepare_heap_for_full_collection() { 1028 // Make sure we'll choose a new allocation region afterwards. 1029 _allocator->release_mutator_alloc_regions(); 1030 _allocator->abandon_gc_alloc_regions(); 1031 1032 // We may have added regions to the current incremental collection 1033 // set between the last GC or pause and now. We need to clear the 1034 // incremental collection set and then start rebuilding it afresh 1035 // after this full GC. 1036 abandon_collection_set(collection_set()); 1037 1038 tear_down_region_sets(false /* free_list_only */); 1039 1040 hrm()->prepare_for_full_collection_start(); 1041 } 1042 1043 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1044 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1045 assert_used_and_recalculate_used_equal(this); 1046 _verifier->verify_region_sets_optional(); 1047 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1048 _verifier->check_bitmaps("Full GC Start"); 1049 } 1050 1051 void G1CollectedHeap::prepare_heap_for_mutators() { 1052 hrm()->prepare_for_full_collection_end(); 1053 1054 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1055 ClassLoaderDataGraph::purge(); 1056 MetaspaceUtils::verify_metrics(); 1057 1058 // Prepare heap for normal collections. 1059 assert(num_free_regions() == 0, "we should not have added any free regions"); 1060 rebuild_region_sets(false /* free_list_only */); 1061 abort_refinement(); 1062 resize_heap_if_necessary(); 1063 1064 // Rebuild the strong code root lists for each region 1065 rebuild_strong_code_roots(); 1066 1067 // Purge code root memory 1068 purge_code_root_memory(); 1069 1070 // Start a new incremental collection set for the next pause 1071 start_new_collection_set(); 1072 1073 _allocator->init_mutator_alloc_regions(); 1074 1075 // Post collection state updates. 1076 MetaspaceGC::compute_new_size(); 1077 } 1078 1079 void G1CollectedHeap::abort_refinement() { 1080 if (_hot_card_cache->use_cache()) { 1081 _hot_card_cache->reset_hot_cache(); 1082 } 1083 1084 // Discard all remembered set updates. 1085 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1086 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1087 "DCQS should be empty"); 1088 } 1089 1090 void G1CollectedHeap::verify_after_full_collection() { 1091 _hrm->verify_optional(); 1092 _verifier->verify_region_sets_optional(); 1093 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1094 // Clear the previous marking bitmap, if needed for bitmap verification. 1095 // Note we cannot do this when we clear the next marking bitmap in 1096 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1097 // objects marked during a full GC against the previous bitmap. 1098 // But we need to clear it before calling check_bitmaps below since 1099 // the full GC has compacted objects and updated TAMS but not updated 1100 // the prev bitmap. 1101 if (G1VerifyBitmaps) { 1102 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1103 _cm->clear_prev_bitmap(workers()); 1104 } 1105 // This call implicitly verifies that the next bitmap is clear after Full GC. 1106 _verifier->check_bitmaps("Full GC End"); 1107 1108 // At this point there should be no regions in the 1109 // entire heap tagged as young. 1110 assert(check_young_list_empty(), "young list should be empty at this point"); 1111 1112 // Note: since we've just done a full GC, concurrent 1113 // marking is no longer active. Therefore we need not 1114 // re-enable reference discovery for the CM ref processor. 1115 // That will be done at the start of the next marking cycle. 1116 // We also know that the STW processor should no longer 1117 // discover any new references. 1118 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1119 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1120 _ref_processor_stw->verify_no_references_recorded(); 1121 _ref_processor_cm->verify_no_references_recorded(); 1122 } 1123 1124 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1125 // Post collection logging. 1126 // We should do this after we potentially resize the heap so 1127 // that all the COMMIT / UNCOMMIT events are generated before 1128 // the compaction events. 1129 print_hrm_post_compaction(); 1130 heap_transition->print(); 1131 print_heap_after_gc(); 1132 print_heap_regions(); 1133 #ifdef TRACESPINNING 1134 ParallelTaskTerminator::print_termination_counts(); 1135 #endif 1136 } 1137 1138 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1139 bool clear_all_soft_refs) { 1140 assert_at_safepoint_on_vm_thread(); 1141 1142 if (GCLocker::check_active_before_gc()) { 1143 // Full GC was not completed. 1144 return false; 1145 } 1146 1147 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1148 soft_ref_policy()->should_clear_all_soft_refs(); 1149 1150 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1151 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1152 1153 collector.prepare_collection(); 1154 collector.collect(); 1155 collector.complete_collection(); 1156 1157 // Full collection was successfully completed. 1158 return true; 1159 } 1160 1161 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1162 // Currently, there is no facility in the do_full_collection(bool) API to notify 1163 // the caller that the collection did not succeed (e.g., because it was locked 1164 // out by the GC locker). So, right now, we'll ignore the return value. 1165 bool dummy = do_full_collection(true, /* explicit_gc */ 1166 clear_all_soft_refs); 1167 } 1168 1169 void G1CollectedHeap::resize_heap_if_necessary() { 1170 assert_at_safepoint_on_vm_thread(); 1171 1172 // Capacity, free and used after the GC counted as full regions to 1173 // include the waste in the following calculations. 1174 const size_t capacity_after_gc = capacity(); 1175 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1176 1177 // This is enforced in arguments.cpp. 1178 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1179 "otherwise the code below doesn't make sense"); 1180 1181 // We don't have floating point command-line arguments 1182 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1183 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1184 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1185 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1186 1187 // We have to be careful here as these two calculations can overflow 1188 // 32-bit size_t's. 1189 double used_after_gc_d = (double) used_after_gc; 1190 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1191 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1192 1193 // Let's make sure that they are both under the max heap size, which 1194 // by default will make them fit into a size_t. 1195 double desired_capacity_upper_bound = (double) MaxHeapSize; 1196 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1197 desired_capacity_upper_bound); 1198 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1199 desired_capacity_upper_bound); 1200 1201 // We can now safely turn them into size_t's. 1202 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1203 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1204 1205 // This assert only makes sense here, before we adjust them 1206 // with respect to the min and max heap size. 1207 assert(minimum_desired_capacity <= maximum_desired_capacity, 1208 "minimum_desired_capacity = " SIZE_FORMAT ", " 1209 "maximum_desired_capacity = " SIZE_FORMAT, 1210 minimum_desired_capacity, maximum_desired_capacity); 1211 1212 // Should not be greater than the heap max size. No need to adjust 1213 // it with respect to the heap min size as it's a lower bound (i.e., 1214 // we'll try to make the capacity larger than it, not smaller). 1215 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1216 // Should not be less than the heap min size. No need to adjust it 1217 // with respect to the heap max size as it's an upper bound (i.e., 1218 // we'll try to make the capacity smaller than it, not greater). 1219 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1220 1221 if (capacity_after_gc < minimum_desired_capacity) { 1222 // Don't expand unless it's significant 1223 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1224 1225 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1226 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1227 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1228 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1229 1230 expand(expand_bytes, _workers); 1231 1232 // No expansion, now see if we want to shrink 1233 } else if (capacity_after_gc > maximum_desired_capacity) { 1234 // Capacity too large, compute shrinking size 1235 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1236 1237 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1238 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1239 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1240 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1241 1242 shrink(shrink_bytes); 1243 } 1244 } 1245 1246 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1247 bool do_gc, 1248 bool clear_all_soft_refs, 1249 bool expect_null_mutator_alloc_region, 1250 bool* gc_succeeded) { 1251 *gc_succeeded = true; 1252 // Let's attempt the allocation first. 1253 HeapWord* result = 1254 attempt_allocation_at_safepoint(word_size, 1255 expect_null_mutator_alloc_region); 1256 if (result != NULL) { 1257 return result; 1258 } 1259 1260 // In a G1 heap, we're supposed to keep allocation from failing by 1261 // incremental pauses. Therefore, at least for now, we'll favor 1262 // expansion over collection. (This might change in the future if we can 1263 // do something smarter than full collection to satisfy a failed alloc.) 1264 result = expand_and_allocate(word_size); 1265 if (result != NULL) { 1266 return result; 1267 } 1268 1269 if (do_gc) { 1270 // Expansion didn't work, we'll try to do a Full GC. 1271 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1272 clear_all_soft_refs); 1273 } 1274 1275 return NULL; 1276 } 1277 1278 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1279 bool* succeeded) { 1280 assert_at_safepoint_on_vm_thread(); 1281 1282 // Attempts to allocate followed by Full GC. 1283 HeapWord* result = 1284 satisfy_failed_allocation_helper(word_size, 1285 true, /* do_gc */ 1286 false, /* clear_all_soft_refs */ 1287 false, /* expect_null_mutator_alloc_region */ 1288 succeeded); 1289 1290 if (result != NULL || !*succeeded) { 1291 return result; 1292 } 1293 1294 // Attempts to allocate followed by Full GC that will collect all soft references. 1295 result = satisfy_failed_allocation_helper(word_size, 1296 true, /* do_gc */ 1297 true, /* clear_all_soft_refs */ 1298 true, /* expect_null_mutator_alloc_region */ 1299 succeeded); 1300 1301 if (result != NULL || !*succeeded) { 1302 return result; 1303 } 1304 1305 // Attempts to allocate, no GC 1306 result = satisfy_failed_allocation_helper(word_size, 1307 false, /* do_gc */ 1308 false, /* clear_all_soft_refs */ 1309 true, /* expect_null_mutator_alloc_region */ 1310 succeeded); 1311 1312 if (result != NULL) { 1313 return result; 1314 } 1315 1316 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1317 "Flag should have been handled and cleared prior to this point"); 1318 1319 // What else? We might try synchronous finalization later. If the total 1320 // space available is large enough for the allocation, then a more 1321 // complete compaction phase than we've tried so far might be 1322 // appropriate. 1323 return NULL; 1324 } 1325 1326 // Attempting to expand the heap sufficiently 1327 // to support an allocation of the given "word_size". If 1328 // successful, perform the allocation and return the address of the 1329 // allocated block, or else "NULL". 1330 1331 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1332 assert_at_safepoint_on_vm_thread(); 1333 1334 _verifier->verify_region_sets_optional(); 1335 1336 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1337 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1338 word_size * HeapWordSize); 1339 1340 1341 if (expand(expand_bytes, _workers)) { 1342 _hrm->verify_optional(); 1343 _verifier->verify_region_sets_optional(); 1344 return attempt_allocation_at_safepoint(word_size, 1345 false /* expect_null_mutator_alloc_region */); 1346 } 1347 return NULL; 1348 } 1349 1350 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1351 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1352 aligned_expand_bytes = align_up(aligned_expand_bytes, 1353 HeapRegion::GrainBytes); 1354 1355 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1356 expand_bytes, aligned_expand_bytes); 1357 1358 if (is_maximal_no_gc()) { 1359 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1360 return false; 1361 } 1362 1363 double expand_heap_start_time_sec = os::elapsedTime(); 1364 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1365 assert(regions_to_expand > 0, "Must expand by at least one region"); 1366 1367 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1368 if (expand_time_ms != NULL) { 1369 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1370 } 1371 1372 if (expanded_by > 0) { 1373 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1374 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1375 policy()->record_new_heap_size(num_regions()); 1376 } else { 1377 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1378 1379 // The expansion of the virtual storage space was unsuccessful. 1380 // Let's see if it was because we ran out of swap. 1381 if (G1ExitOnExpansionFailure && 1382 _hrm->available() >= regions_to_expand) { 1383 // We had head room... 1384 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1385 } 1386 } 1387 return regions_to_expand > 0; 1388 } 1389 1390 bool G1CollectedHeap::expand_single_region(uint node_index) { 1391 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1392 1393 if (expanded_by == 0) { 1394 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1395 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1396 return false; 1397 } 1398 1399 policy()->record_new_heap_size(num_regions()); 1400 return true; 1401 } 1402 1403 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1404 size_t aligned_shrink_bytes = 1405 ReservedSpace::page_align_size_down(shrink_bytes); 1406 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1407 HeapRegion::GrainBytes); 1408 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1409 1410 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1411 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1412 1413 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B", 1414 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1415 if (num_regions_removed > 0) { 1416 policy()->record_new_heap_size(num_regions()); 1417 } else { 1418 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1419 } 1420 } 1421 1422 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1423 _verifier->verify_region_sets_optional(); 1424 1425 // We should only reach here at the end of a Full GC or during Remark which 1426 // means we should not not be holding to any GC alloc regions. The method 1427 // below will make sure of that and do any remaining clean up. 1428 _allocator->abandon_gc_alloc_regions(); 1429 1430 // Instead of tearing down / rebuilding the free lists here, we 1431 // could instead use the remove_all_pending() method on free_list to 1432 // remove only the ones that we need to remove. 1433 tear_down_region_sets(true /* free_list_only */); 1434 shrink_helper(shrink_bytes); 1435 rebuild_region_sets(true /* free_list_only */); 1436 1437 _hrm->verify_optional(); 1438 _verifier->verify_region_sets_optional(); 1439 } 1440 1441 class OldRegionSetChecker : public HeapRegionSetChecker { 1442 public: 1443 void check_mt_safety() { 1444 // Master Old Set MT safety protocol: 1445 // (a) If we're at a safepoint, operations on the master old set 1446 // should be invoked: 1447 // - by the VM thread (which will serialize them), or 1448 // - by the GC workers while holding the FreeList_lock, if we're 1449 // at a safepoint for an evacuation pause (this lock is taken 1450 // anyway when an GC alloc region is retired so that a new one 1451 // is allocated from the free list), or 1452 // - by the GC workers while holding the OldSets_lock, if we're at a 1453 // safepoint for a cleanup pause. 1454 // (b) If we're not at a safepoint, operations on the master old set 1455 // should be invoked while holding the Heap_lock. 1456 1457 if (SafepointSynchronize::is_at_safepoint()) { 1458 guarantee(Thread::current()->is_VM_thread() || 1459 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1460 "master old set MT safety protocol at a safepoint"); 1461 } else { 1462 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1463 } 1464 } 1465 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1466 const char* get_description() { return "Old Regions"; } 1467 }; 1468 1469 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1470 public: 1471 void check_mt_safety() { 1472 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1473 "May only change archive regions during initialization or safepoint."); 1474 } 1475 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1476 const char* get_description() { return "Archive Regions"; } 1477 }; 1478 1479 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1480 public: 1481 void check_mt_safety() { 1482 // Humongous Set MT safety protocol: 1483 // (a) If we're at a safepoint, operations on the master humongous 1484 // set should be invoked by either the VM thread (which will 1485 // serialize them) or by the GC workers while holding the 1486 // OldSets_lock. 1487 // (b) If we're not at a safepoint, operations on the master 1488 // humongous set should be invoked while holding the Heap_lock. 1489 1490 if (SafepointSynchronize::is_at_safepoint()) { 1491 guarantee(Thread::current()->is_VM_thread() || 1492 OldSets_lock->owned_by_self(), 1493 "master humongous set MT safety protocol at a safepoint"); 1494 } else { 1495 guarantee(Heap_lock->owned_by_self(), 1496 "master humongous set MT safety protocol outside a safepoint"); 1497 } 1498 } 1499 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1500 const char* get_description() { return "Humongous Regions"; } 1501 }; 1502 1503 G1CollectedHeap::G1CollectedHeap() : 1504 CollectedHeap(), 1505 _young_gen_sampling_thread(NULL), 1506 _workers(NULL), 1507 _card_table(NULL), 1508 _soft_ref_policy(), 1509 _old_set("Old Region Set", new OldRegionSetChecker()), 1510 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1511 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1512 _bot(NULL), 1513 _listener(), 1514 _numa(G1NUMA::create()), 1515 _hrm(NULL), 1516 _allocator(NULL), 1517 _verifier(NULL), 1518 _summary_bytes_used(0), 1519 _archive_allocator(NULL), 1520 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1521 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1522 _expand_heap_after_alloc_failure(true), 1523 _g1mm(NULL), 1524 _humongous_reclaim_candidates(), 1525 _has_humongous_reclaim_candidates(false), 1526 _hr_printer(), 1527 _collector_state(), 1528 _old_marking_cycles_started(0), 1529 _old_marking_cycles_completed(0), 1530 _eden(), 1531 _survivor(), 1532 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1533 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1534 _policy(G1Policy::create_policy(_gc_timer_stw)), 1535 _heap_sizing_policy(NULL), 1536 _collection_set(this, _policy), 1537 _hot_card_cache(NULL), 1538 _rem_set(NULL), 1539 _cm(NULL), 1540 _cm_thread(NULL), 1541 _cr(NULL), 1542 _task_queues(NULL), 1543 _evacuation_failed(false), 1544 _evacuation_failed_info_array(NULL), 1545 _preserved_marks_set(true /* in_c_heap */), 1546 #ifndef PRODUCT 1547 _evacuation_failure_alot_for_current_gc(false), 1548 _evacuation_failure_alot_gc_number(0), 1549 _evacuation_failure_alot_count(0), 1550 #endif 1551 _ref_processor_stw(NULL), 1552 _is_alive_closure_stw(this), 1553 _is_subject_to_discovery_stw(this), 1554 _ref_processor_cm(NULL), 1555 _is_alive_closure_cm(this), 1556 _is_subject_to_discovery_cm(this), 1557 _region_attr() { 1558 1559 _verifier = new G1HeapVerifier(this); 1560 1561 _allocator = new G1Allocator(this); 1562 1563 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1564 1565 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1566 1567 // Override the default _filler_array_max_size so that no humongous filler 1568 // objects are created. 1569 _filler_array_max_size = _humongous_object_threshold_in_words; 1570 1571 uint n_queues = ParallelGCThreads; 1572 _task_queues = new RefToScanQueueSet(n_queues); 1573 1574 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1575 1576 for (uint i = 0; i < n_queues; i++) { 1577 RefToScanQueue* q = new RefToScanQueue(); 1578 q->initialize(); 1579 _task_queues->register_queue(i, q); 1580 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1581 } 1582 1583 // Initialize the G1EvacuationFailureALot counters and flags. 1584 NOT_PRODUCT(reset_evacuation_should_fail();) 1585 _gc_tracer_stw->initialize(); 1586 1587 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1588 } 1589 1590 static size_t actual_reserved_page_size(ReservedSpace rs) { 1591 size_t page_size = os::vm_page_size(); 1592 if (UseLargePages) { 1593 // There are two ways to manage large page memory. 1594 // 1. OS supports committing large page memory. 1595 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1596 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1597 // we reserved memory without large page. 1598 if (os::can_commit_large_page_memory() || rs.special()) { 1599 // An alignment at ReservedSpace comes from preferred page size or 1600 // heap alignment, and if the alignment came from heap alignment, it could be 1601 // larger than large pages size. So need to cap with the large page size. 1602 page_size = MIN2(rs.alignment(), os::large_page_size()); 1603 } 1604 } 1605 1606 return page_size; 1607 } 1608 1609 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1610 size_t size, 1611 size_t translation_factor) { 1612 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1613 // Allocate a new reserved space, preferring to use large pages. 1614 ReservedSpace rs(size, preferred_page_size); 1615 size_t page_size = actual_reserved_page_size(rs); 1616 G1RegionToSpaceMapper* result = 1617 G1RegionToSpaceMapper::create_mapper(rs, 1618 size, 1619 page_size, 1620 HeapRegion::GrainBytes, 1621 translation_factor, 1622 mtGC); 1623 1624 os::trace_page_sizes_for_requested_size(description, 1625 size, 1626 preferred_page_size, 1627 page_size, 1628 rs.base(), 1629 rs.size()); 1630 1631 return result; 1632 } 1633 1634 jint G1CollectedHeap::initialize_concurrent_refinement() { 1635 jint ecode = JNI_OK; 1636 _cr = G1ConcurrentRefine::create(&ecode); 1637 return ecode; 1638 } 1639 1640 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1641 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1642 if (_young_gen_sampling_thread->osthread() == NULL) { 1643 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1644 return JNI_ENOMEM; 1645 } 1646 return JNI_OK; 1647 } 1648 1649 jint G1CollectedHeap::initialize() { 1650 1651 // Necessary to satisfy locking discipline assertions. 1652 1653 MutexLocker x(Heap_lock); 1654 1655 // While there are no constraints in the GC code that HeapWordSize 1656 // be any particular value, there are multiple other areas in the 1657 // system which believe this to be true (e.g. oop->object_size in some 1658 // cases incorrectly returns the size in wordSize units rather than 1659 // HeapWordSize). 1660 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1661 1662 size_t init_byte_size = InitialHeapSize; 1663 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1664 1665 // Ensure that the sizes are properly aligned. 1666 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1667 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1668 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1669 1670 // Reserve the maximum. 1671 1672 // When compressed oops are enabled, the preferred heap base 1673 // is calculated by subtracting the requested size from the 1674 // 32Gb boundary and using the result as the base address for 1675 // heap reservation. If the requested size is not aligned to 1676 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1677 // into the ReservedHeapSpace constructor) then the actual 1678 // base of the reserved heap may end up differing from the 1679 // address that was requested (i.e. the preferred heap base). 1680 // If this happens then we could end up using a non-optimal 1681 // compressed oops mode. 1682 1683 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1684 HeapAlignment); 1685 1686 initialize_reserved_region(heap_rs); 1687 1688 // Create the barrier set for the entire reserved region. 1689 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1690 ct->initialize(); 1691 G1BarrierSet* bs = new G1BarrierSet(ct); 1692 bs->initialize(); 1693 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1694 BarrierSet::set_barrier_set(bs); 1695 _card_table = ct; 1696 1697 { 1698 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1699 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1700 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1701 } 1702 1703 // Create the hot card cache. 1704 _hot_card_cache = new G1HotCardCache(this); 1705 1706 // Carve out the G1 part of the heap. 1707 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1708 size_t page_size = actual_reserved_page_size(heap_rs); 1709 G1RegionToSpaceMapper* heap_storage = 1710 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1711 g1_rs.size(), 1712 page_size, 1713 HeapRegion::GrainBytes, 1714 1, 1715 mtJavaHeap); 1716 if(heap_storage == NULL) { 1717 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1718 return JNI_ERR; 1719 } 1720 1721 os::trace_page_sizes("Heap", 1722 MinHeapSize, 1723 reserved_byte_size, 1724 page_size, 1725 heap_rs.base(), 1726 heap_rs.size()); 1727 heap_storage->set_mapping_changed_listener(&_listener); 1728 1729 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1730 G1RegionToSpaceMapper* bot_storage = 1731 create_aux_memory_mapper("Block Offset Table", 1732 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1733 G1BlockOffsetTable::heap_map_factor()); 1734 1735 G1RegionToSpaceMapper* cardtable_storage = 1736 create_aux_memory_mapper("Card Table", 1737 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1738 G1CardTable::heap_map_factor()); 1739 1740 G1RegionToSpaceMapper* card_counts_storage = 1741 create_aux_memory_mapper("Card Counts Table", 1742 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1743 G1CardCounts::heap_map_factor()); 1744 1745 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1746 G1RegionToSpaceMapper* prev_bitmap_storage = 1747 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1748 G1RegionToSpaceMapper* next_bitmap_storage = 1749 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1750 1751 _hrm = HeapRegionManager::create_manager(this); 1752 1753 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1754 _card_table->initialize(cardtable_storage); 1755 1756 // Do later initialization work for concurrent refinement. 1757 _hot_card_cache->initialize(card_counts_storage); 1758 1759 // 6843694 - ensure that the maximum region index can fit 1760 // in the remembered set structures. 1761 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1762 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1763 1764 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1765 // start within the first card. 1766 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1767 // Also create a G1 rem set. 1768 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1769 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1770 1771 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1772 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1773 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1774 "too many cards per region"); 1775 1776 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1777 1778 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1779 1780 { 1781 HeapWord* start = _hrm->reserved().start(); 1782 HeapWord* end = _hrm->reserved().end(); 1783 size_t granularity = HeapRegion::GrainBytes; 1784 1785 _region_attr.initialize(start, end, granularity); 1786 _humongous_reclaim_candidates.initialize(start, end, granularity); 1787 } 1788 1789 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1790 true /* are_GC_task_threads */, 1791 false /* are_ConcurrentGC_threads */); 1792 if (_workers == NULL) { 1793 return JNI_ENOMEM; 1794 } 1795 _workers->initialize_workers(); 1796 1797 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1798 1799 // Create the G1ConcurrentMark data structure and thread. 1800 // (Must do this late, so that "max_regions" is defined.) 1801 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1802 if (_cm == NULL || !_cm->completed_initialization()) { 1803 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1804 return JNI_ENOMEM; 1805 } 1806 _cm_thread = _cm->cm_thread(); 1807 1808 // Now expand into the initial heap size. 1809 if (!expand(init_byte_size, _workers)) { 1810 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1811 return JNI_ENOMEM; 1812 } 1813 1814 // Perform any initialization actions delegated to the policy. 1815 policy()->init(this, &_collection_set); 1816 1817 jint ecode = initialize_concurrent_refinement(); 1818 if (ecode != JNI_OK) { 1819 return ecode; 1820 } 1821 1822 ecode = initialize_young_gen_sampling_thread(); 1823 if (ecode != JNI_OK) { 1824 return ecode; 1825 } 1826 1827 { 1828 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1829 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1830 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1831 } 1832 1833 // Here we allocate the dummy HeapRegion that is required by the 1834 // G1AllocRegion class. 1835 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1836 1837 // We'll re-use the same region whether the alloc region will 1838 // require BOT updates or not and, if it doesn't, then a non-young 1839 // region will complain that it cannot support allocations without 1840 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1841 dummy_region->set_eden(); 1842 // Make sure it's full. 1843 dummy_region->set_top(dummy_region->end()); 1844 G1AllocRegion::setup(this, dummy_region); 1845 1846 _allocator->init_mutator_alloc_regions(); 1847 1848 // Do create of the monitoring and management support so that 1849 // values in the heap have been properly initialized. 1850 _g1mm = new G1MonitoringSupport(this); 1851 1852 G1StringDedup::initialize(); 1853 1854 _preserved_marks_set.init(ParallelGCThreads); 1855 1856 _collection_set.initialize(max_regions()); 1857 1858 return JNI_OK; 1859 } 1860 1861 void G1CollectedHeap::stop() { 1862 // Stop all concurrent threads. We do this to make sure these threads 1863 // do not continue to execute and access resources (e.g. logging) 1864 // that are destroyed during shutdown. 1865 _cr->stop(); 1866 _young_gen_sampling_thread->stop(); 1867 _cm_thread->stop(); 1868 if (G1StringDedup::is_enabled()) { 1869 G1StringDedup::stop(); 1870 } 1871 } 1872 1873 void G1CollectedHeap::safepoint_synchronize_begin() { 1874 SuspendibleThreadSet::synchronize(); 1875 } 1876 1877 void G1CollectedHeap::safepoint_synchronize_end() { 1878 SuspendibleThreadSet::desynchronize(); 1879 } 1880 1881 void G1CollectedHeap::post_initialize() { 1882 CollectedHeap::post_initialize(); 1883 ref_processing_init(); 1884 } 1885 1886 void G1CollectedHeap::ref_processing_init() { 1887 // Reference processing in G1 currently works as follows: 1888 // 1889 // * There are two reference processor instances. One is 1890 // used to record and process discovered references 1891 // during concurrent marking; the other is used to 1892 // record and process references during STW pauses 1893 // (both full and incremental). 1894 // * Both ref processors need to 'span' the entire heap as 1895 // the regions in the collection set may be dotted around. 1896 // 1897 // * For the concurrent marking ref processor: 1898 // * Reference discovery is enabled at initial marking. 1899 // * Reference discovery is disabled and the discovered 1900 // references processed etc during remarking. 1901 // * Reference discovery is MT (see below). 1902 // * Reference discovery requires a barrier (see below). 1903 // * Reference processing may or may not be MT 1904 // (depending on the value of ParallelRefProcEnabled 1905 // and ParallelGCThreads). 1906 // * A full GC disables reference discovery by the CM 1907 // ref processor and abandons any entries on it's 1908 // discovered lists. 1909 // 1910 // * For the STW processor: 1911 // * Non MT discovery is enabled at the start of a full GC. 1912 // * Processing and enqueueing during a full GC is non-MT. 1913 // * During a full GC, references are processed after marking. 1914 // 1915 // * Discovery (may or may not be MT) is enabled at the start 1916 // of an incremental evacuation pause. 1917 // * References are processed near the end of a STW evacuation pause. 1918 // * For both types of GC: 1919 // * Discovery is atomic - i.e. not concurrent. 1920 // * Reference discovery will not need a barrier. 1921 1922 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1923 1924 // Concurrent Mark ref processor 1925 _ref_processor_cm = 1926 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1927 mt_processing, // mt processing 1928 ParallelGCThreads, // degree of mt processing 1929 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1930 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1931 false, // Reference discovery is not atomic 1932 &_is_alive_closure_cm, // is alive closure 1933 true); // allow changes to number of processing threads 1934 1935 // STW ref processor 1936 _ref_processor_stw = 1937 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1938 mt_processing, // mt processing 1939 ParallelGCThreads, // degree of mt processing 1940 (ParallelGCThreads > 1), // mt discovery 1941 ParallelGCThreads, // degree of mt discovery 1942 true, // Reference discovery is atomic 1943 &_is_alive_closure_stw, // is alive closure 1944 true); // allow changes to number of processing threads 1945 } 1946 1947 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1948 return &_soft_ref_policy; 1949 } 1950 1951 size_t G1CollectedHeap::capacity() const { 1952 return _hrm->length() * HeapRegion::GrainBytes; 1953 } 1954 1955 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1956 return _hrm->total_free_bytes(); 1957 } 1958 1959 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1960 _hot_card_cache->drain(cl, worker_id); 1961 } 1962 1963 // Computes the sum of the storage used by the various regions. 1964 size_t G1CollectedHeap::used() const { 1965 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1966 if (_archive_allocator != NULL) { 1967 result += _archive_allocator->used(); 1968 } 1969 return result; 1970 } 1971 1972 size_t G1CollectedHeap::used_unlocked() const { 1973 return _summary_bytes_used; 1974 } 1975 1976 class SumUsedClosure: public HeapRegionClosure { 1977 size_t _used; 1978 public: 1979 SumUsedClosure() : _used(0) {} 1980 bool do_heap_region(HeapRegion* r) { 1981 _used += r->used(); 1982 return false; 1983 } 1984 size_t result() { return _used; } 1985 }; 1986 1987 size_t G1CollectedHeap::recalculate_used() const { 1988 SumUsedClosure blk; 1989 heap_region_iterate(&blk); 1990 return blk.result(); 1991 } 1992 1993 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1994 switch (cause) { 1995 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1996 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1997 case GCCause::_wb_conc_mark: return true; 1998 default : return false; 1999 } 2000 } 2001 2002 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2003 switch (cause) { 2004 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2005 case GCCause::_g1_humongous_allocation: return true; 2006 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2007 default: return is_user_requested_concurrent_full_gc(cause); 2008 } 2009 } 2010 2011 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2012 if (policy()->force_upgrade_to_full()) { 2013 return true; 2014 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2015 return false; 2016 } else if (has_regions_left_for_allocation()) { 2017 return false; 2018 } else { 2019 return true; 2020 } 2021 } 2022 2023 #ifndef PRODUCT 2024 void G1CollectedHeap::allocate_dummy_regions() { 2025 // Let's fill up most of the region 2026 size_t word_size = HeapRegion::GrainWords - 1024; 2027 // And as a result the region we'll allocate will be humongous. 2028 guarantee(is_humongous(word_size), "sanity"); 2029 2030 // _filler_array_max_size is set to humongous object threshold 2031 // but temporarily change it to use CollectedHeap::fill_with_object(). 2032 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2033 2034 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2035 // Let's use the existing mechanism for the allocation 2036 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2037 if (dummy_obj != NULL) { 2038 MemRegion mr(dummy_obj, word_size); 2039 CollectedHeap::fill_with_object(mr); 2040 } else { 2041 // If we can't allocate once, we probably cannot allocate 2042 // again. Let's get out of the loop. 2043 break; 2044 } 2045 } 2046 } 2047 #endif // !PRODUCT 2048 2049 void G1CollectedHeap::increment_old_marking_cycles_started() { 2050 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2051 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2052 "Wrong marking cycle count (started: %d, completed: %d)", 2053 _old_marking_cycles_started, _old_marking_cycles_completed); 2054 2055 _old_marking_cycles_started++; 2056 } 2057 2058 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2059 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 2060 2061 // We assume that if concurrent == true, then the caller is a 2062 // concurrent thread that was joined the Suspendible Thread 2063 // Set. If there's ever a cheap way to check this, we should add an 2064 // assert here. 2065 2066 // Given that this method is called at the end of a Full GC or of a 2067 // concurrent cycle, and those can be nested (i.e., a Full GC can 2068 // interrupt a concurrent cycle), the number of full collections 2069 // completed should be either one (in the case where there was no 2070 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2071 // behind the number of full collections started. 2072 2073 // This is the case for the inner caller, i.e. a Full GC. 2074 assert(concurrent || 2075 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2076 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2077 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2078 "is inconsistent with _old_marking_cycles_completed = %u", 2079 _old_marking_cycles_started, _old_marking_cycles_completed); 2080 2081 // This is the case for the outer caller, i.e. the concurrent cycle. 2082 assert(!concurrent || 2083 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2084 "for outer caller (concurrent cycle): " 2085 "_old_marking_cycles_started = %u " 2086 "is inconsistent with _old_marking_cycles_completed = %u", 2087 _old_marking_cycles_started, _old_marking_cycles_completed); 2088 2089 _old_marking_cycles_completed += 1; 2090 2091 // We need to clear the "in_progress" flag in the CM thread before 2092 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2093 // is set) so that if a waiter requests another System.gc() it doesn't 2094 // incorrectly see that a marking cycle is still in progress. 2095 if (concurrent) { 2096 _cm_thread->set_idle(); 2097 } 2098 2099 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 2100 // for a full GC to finish that their wait is over. 2101 ml.notify_all(); 2102 } 2103 2104 void G1CollectedHeap::collect(GCCause::Cause cause) { 2105 try_collect(cause); 2106 } 2107 2108 // Return true if (x < y) with allowance for wraparound. 2109 static bool gc_counter_less_than(uint x, uint y) { 2110 return (x - y) > (UINT_MAX/2); 2111 } 2112 2113 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 2114 // Macro so msg printing is format-checked. 2115 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 2116 do { \ 2117 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 2118 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 2119 ResourceMark rm; /* For thread name. */ \ 2120 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 2121 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 2122 Thread::current()->name(), \ 2123 GCCause::to_string(cause)); \ 2124 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 2125 } \ 2126 } while (0) 2127 2128 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 2129 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 2130 2131 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 2132 uint gc_counter, 2133 uint old_marking_started_before) { 2134 assert_heap_not_locked(); 2135 assert(should_do_concurrent_full_gc(cause), 2136 "Non-concurrent cause %s", GCCause::to_string(cause)); 2137 2138 for (uint i = 1; true; ++i) { 2139 // Try to schedule an initial-mark evacuation pause that will 2140 // start a concurrent cycle. 2141 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 2142 VM_G1TryInitiateConcMark op(gc_counter, 2143 cause, 2144 policy()->max_pause_time_ms()); 2145 VMThread::execute(&op); 2146 2147 // Request is trivially finished. 2148 if (cause == GCCause::_g1_periodic_collection) { 2149 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 2150 return op.gc_succeeded(); 2151 } 2152 2153 // Lock to get consistent set of values. 2154 uint old_marking_started_after; 2155 uint old_marking_completed_after; 2156 { 2157 MutexLocker ml(Heap_lock); 2158 // Update gc_counter for retrying VMOp if needed. Captured here to be 2159 // consistent with the values we use below for termination tests. If 2160 // a retry is needed after a possible wait, and another collection 2161 // occurs in the meantime, it will cause our retry to be skipped and 2162 // we'll recheck for termination with updated conditions from that 2163 // more recent collection. That's what we want, rather than having 2164 // our retry possibly perform an unnecessary collection. 2165 gc_counter = total_collections(); 2166 old_marking_started_after = _old_marking_cycles_started; 2167 old_marking_completed_after = _old_marking_cycles_completed; 2168 } 2169 2170 if (!GCCause::is_user_requested_gc(cause)) { 2171 // For an "automatic" (not user-requested) collection, we just need to 2172 // ensure that progress is made. 2173 // 2174 // Request is finished if any of 2175 // (1) the VMOp successfully performed a GC, 2176 // (2) a concurrent cycle was already in progress, 2177 // (3) a new cycle was started (by this thread or some other), or 2178 // (4) a Full GC was performed. 2179 // Cases (3) and (4) are detected together by a change to 2180 // _old_marking_cycles_started. 2181 // 2182 // Note that (1) does not imply (3). If we're still in the mixed 2183 // phase of an earlier concurrent collection, the request to make the 2184 // collection an initial-mark won't be honored. If we don't check for 2185 // both conditions we'll spin doing back-to-back collections. 2186 if (op.gc_succeeded() || 2187 op.cycle_already_in_progress() || 2188 (old_marking_started_before != old_marking_started_after)) { 2189 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2190 return true; 2191 } 2192 } else { // User-requested GC. 2193 // For a user-requested collection, we want to ensure that a complete 2194 // full collection has been performed before returning, but without 2195 // waiting for more than needed. 2196 2197 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 2198 // new cycle was started. That's good, because it's not clear what we 2199 // should do otherwise. Trying again just does back to back GCs. 2200 // Can't wait for someone else to start a cycle. And returning fails 2201 // to meet the goal of ensuring a full collection was performed. 2202 assert(!op.gc_succeeded() || 2203 (old_marking_started_before != old_marking_started_after), 2204 "invariant: succeeded %s, started before %u, started after %u", 2205 BOOL_TO_STR(op.gc_succeeded()), 2206 old_marking_started_before, old_marking_started_after); 2207 2208 // Request is finished if a full collection (concurrent or stw) 2209 // was started after this request and has completed, e.g. 2210 // started_before < completed_after. 2211 if (gc_counter_less_than(old_marking_started_before, 2212 old_marking_completed_after)) { 2213 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2214 return true; 2215 } 2216 2217 if (old_marking_started_after != old_marking_completed_after) { 2218 // If there is an in-progress cycle (possibly started by us), then 2219 // wait for that cycle to complete, e.g. 2220 // while completed_now < started_after. 2221 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2222 MonitorLocker ml(G1OldGCCount_lock); 2223 while (gc_counter_less_than(_old_marking_cycles_completed, 2224 old_marking_started_after)) { 2225 ml.wait(); 2226 } 2227 // Request is finished if the collection we just waited for was 2228 // started after this request. 2229 if (old_marking_started_before != old_marking_started_after) { 2230 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2231 return true; 2232 } 2233 } 2234 2235 // If VMOp was successful then it started a new cycle that the above 2236 // wait &etc should have recognized as finishing this request. This 2237 // differs from a non-user-request, where gc_succeeded does not imply 2238 // a new cycle was started. 2239 assert(!op.gc_succeeded(), "invariant"); 2240 2241 // If VMOp failed because a cycle was already in progress, it is now 2242 // complete. But it didn't finish this user-requested GC, so try 2243 // again. 2244 if (op.cycle_already_in_progress()) { 2245 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2246 continue; 2247 } 2248 } 2249 2250 // Collection failed and should be retried. 2251 assert(op.transient_failure(), "invariant"); 2252 2253 // If GCLocker is active, wait until clear before retrying. 2254 if (GCLocker::is_active_and_needs_gc()) { 2255 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2256 GCLocker::stall_until_clear(); 2257 } 2258 2259 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2260 } 2261 } 2262 2263 bool G1CollectedHeap::try_collect(GCCause::Cause cause) { 2264 assert_heap_not_locked(); 2265 2266 // Lock to get consistent set of values. 2267 uint gc_count_before; 2268 uint full_gc_count_before; 2269 uint old_marking_started_before; 2270 { 2271 MutexLocker ml(Heap_lock); 2272 gc_count_before = total_collections(); 2273 full_gc_count_before = total_full_collections(); 2274 old_marking_started_before = _old_marking_cycles_started; 2275 } 2276 2277 if (should_do_concurrent_full_gc(cause)) { 2278 return try_collect_concurrently(cause, 2279 gc_count_before, 2280 old_marking_started_before); 2281 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2282 // Indicate failure to be consistent with VMOp failure due to 2283 // another collection slipping in after our gc_count but before 2284 // our request is processed. _gc_locker collections upgraded by 2285 // GCLockerInvokesConcurrent are handled above and never discarded. 2286 return false; 2287 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2288 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2289 2290 // Schedule a standard evacuation pause. We're setting word_size 2291 // to 0 which means that we are not requesting a post-GC allocation. 2292 VM_G1CollectForAllocation op(0, /* word_size */ 2293 gc_count_before, 2294 cause, 2295 policy()->max_pause_time_ms()); 2296 VMThread::execute(&op); 2297 return op.gc_succeeded(); 2298 } else { 2299 // Schedule a Full GC. 2300 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2301 VMThread::execute(&op); 2302 return op.gc_succeeded(); 2303 } 2304 } 2305 2306 bool G1CollectedHeap::is_in(const void* p) const { 2307 if (_hrm->reserved().contains(p)) { 2308 // Given that we know that p is in the reserved space, 2309 // heap_region_containing() should successfully 2310 // return the containing region. 2311 HeapRegion* hr = heap_region_containing(p); 2312 return hr->is_in(p); 2313 } else { 2314 return false; 2315 } 2316 } 2317 2318 #ifdef ASSERT 2319 bool G1CollectedHeap::is_in_exact(const void* p) const { 2320 bool contains = reserved_region().contains(p); 2321 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2322 if (contains && available) { 2323 return true; 2324 } else { 2325 return false; 2326 } 2327 } 2328 #endif 2329 2330 // Iteration functions. 2331 2332 // Iterates an ObjectClosure over all objects within a HeapRegion. 2333 2334 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2335 ObjectClosure* _cl; 2336 public: 2337 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2338 bool do_heap_region(HeapRegion* r) { 2339 if (!r->is_continues_humongous()) { 2340 r->object_iterate(_cl); 2341 } 2342 return false; 2343 } 2344 }; 2345 2346 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2347 IterateObjectClosureRegionClosure blk(cl); 2348 heap_region_iterate(&blk); 2349 } 2350 2351 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2352 _hrm->iterate(cl); 2353 } 2354 2355 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2356 HeapRegionClaimer *hrclaimer, 2357 uint worker_id) const { 2358 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2359 } 2360 2361 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2362 HeapRegionClaimer *hrclaimer) const { 2363 _hrm->par_iterate(cl, hrclaimer, 0); 2364 } 2365 2366 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2367 _collection_set.iterate(cl); 2368 } 2369 2370 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2371 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2372 } 2373 2374 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2375 HeapRegion* hr = heap_region_containing(addr); 2376 return hr->block_start(addr); 2377 } 2378 2379 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2380 HeapRegion* hr = heap_region_containing(addr); 2381 return hr->block_is_obj(addr); 2382 } 2383 2384 bool G1CollectedHeap::supports_tlab_allocation() const { 2385 return true; 2386 } 2387 2388 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2389 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2390 } 2391 2392 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2393 return _eden.length() * HeapRegion::GrainBytes; 2394 } 2395 2396 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2397 // must be equal to the humongous object limit. 2398 size_t G1CollectedHeap::max_tlab_size() const { 2399 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2400 } 2401 2402 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2403 return _allocator->unsafe_max_tlab_alloc(); 2404 } 2405 2406 size_t G1CollectedHeap::max_capacity() const { 2407 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2408 } 2409 2410 size_t G1CollectedHeap::max_reserved_capacity() const { 2411 return _hrm->max_length() * HeapRegion::GrainBytes; 2412 } 2413 2414 jlong G1CollectedHeap::millis_since_last_gc() { 2415 // See the notes in GenCollectedHeap::millis_since_last_gc() 2416 // for more information about the implementation. 2417 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2418 _policy->collection_pause_end_millis(); 2419 if (ret_val < 0) { 2420 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2421 ". returning zero instead.", ret_val); 2422 return 0; 2423 } 2424 return ret_val; 2425 } 2426 2427 void G1CollectedHeap::deduplicate_string(oop str) { 2428 assert(java_lang_String::is_instance(str), "invariant"); 2429 2430 if (G1StringDedup::is_enabled()) { 2431 G1StringDedup::deduplicate(str); 2432 } 2433 } 2434 2435 void G1CollectedHeap::prepare_for_verify() { 2436 _verifier->prepare_for_verify(); 2437 } 2438 2439 void G1CollectedHeap::verify(VerifyOption vo) { 2440 _verifier->verify(vo); 2441 } 2442 2443 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2444 return true; 2445 } 2446 2447 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2448 return _cm_thread->request_concurrent_phase(phase); 2449 } 2450 2451 bool G1CollectedHeap::is_heterogeneous_heap() const { 2452 return G1Arguments::is_heterogeneous_heap(); 2453 } 2454 2455 class PrintRegionClosure: public HeapRegionClosure { 2456 outputStream* _st; 2457 public: 2458 PrintRegionClosure(outputStream* st) : _st(st) {} 2459 bool do_heap_region(HeapRegion* r) { 2460 r->print_on(_st); 2461 return false; 2462 } 2463 }; 2464 2465 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2466 const HeapRegion* hr, 2467 const VerifyOption vo) const { 2468 switch (vo) { 2469 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2470 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2471 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2472 default: ShouldNotReachHere(); 2473 } 2474 return false; // keep some compilers happy 2475 } 2476 2477 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2478 const VerifyOption vo) const { 2479 switch (vo) { 2480 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2481 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2482 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2483 default: ShouldNotReachHere(); 2484 } 2485 return false; // keep some compilers happy 2486 } 2487 2488 void G1CollectedHeap::print_heap_regions() const { 2489 LogTarget(Trace, gc, heap, region) lt; 2490 if (lt.is_enabled()) { 2491 LogStream ls(lt); 2492 print_regions_on(&ls); 2493 } 2494 } 2495 2496 void G1CollectedHeap::print_on(outputStream* st) const { 2497 st->print(" %-20s", "garbage-first heap"); 2498 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2499 capacity()/K, used_unlocked()/K); 2500 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2501 p2i(_hrm->reserved().start()), 2502 p2i(_hrm->reserved().end())); 2503 st->cr(); 2504 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2505 uint young_regions = young_regions_count(); 2506 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2507 (size_t) young_regions * HeapRegion::GrainBytes / K); 2508 uint survivor_regions = survivor_regions_count(); 2509 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2510 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2511 st->cr(); 2512 if (_numa->is_enabled()) { 2513 uint num_nodes = _numa->num_active_nodes(); 2514 st->print(" remaining free region(s) on each NUMA node: "); 2515 const int* node_ids = _numa->node_ids(); 2516 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2517 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index)); 2518 } 2519 st->cr(); 2520 } 2521 MetaspaceUtils::print_on(st); 2522 } 2523 2524 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2525 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2526 "HS=humongous(starts), HC=humongous(continues), " 2527 "CS=collection set, F=free, " 2528 "OA=open archive, CA=closed archive, " 2529 "TAMS=top-at-mark-start (previous, next)"); 2530 PrintRegionClosure blk(st); 2531 heap_region_iterate(&blk); 2532 } 2533 2534 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2535 print_on(st); 2536 2537 // Print the per-region information. 2538 print_regions_on(st); 2539 } 2540 2541 void G1CollectedHeap::print_on_error(outputStream* st) const { 2542 this->CollectedHeap::print_on_error(st); 2543 2544 if (_cm != NULL) { 2545 st->cr(); 2546 _cm->print_on_error(st); 2547 } 2548 } 2549 2550 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2551 workers()->print_worker_threads_on(st); 2552 _cm_thread->print_on(st); 2553 st->cr(); 2554 _cm->print_worker_threads_on(st); 2555 _cr->print_threads_on(st); 2556 _young_gen_sampling_thread->print_on(st); 2557 if (G1StringDedup::is_enabled()) { 2558 G1StringDedup::print_worker_threads_on(st); 2559 } 2560 } 2561 2562 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2563 workers()->threads_do(tc); 2564 tc->do_thread(_cm_thread); 2565 _cm->threads_do(tc); 2566 _cr->threads_do(tc); 2567 tc->do_thread(_young_gen_sampling_thread); 2568 if (G1StringDedup::is_enabled()) { 2569 G1StringDedup::threads_do(tc); 2570 } 2571 } 2572 2573 void G1CollectedHeap::print_tracing_info() const { 2574 rem_set()->print_summary_info(); 2575 concurrent_mark()->print_summary_info(); 2576 } 2577 2578 #ifndef PRODUCT 2579 // Helpful for debugging RSet issues. 2580 2581 class PrintRSetsClosure : public HeapRegionClosure { 2582 private: 2583 const char* _msg; 2584 size_t _occupied_sum; 2585 2586 public: 2587 bool do_heap_region(HeapRegion* r) { 2588 HeapRegionRemSet* hrrs = r->rem_set(); 2589 size_t occupied = hrrs->occupied(); 2590 _occupied_sum += occupied; 2591 2592 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2593 if (occupied == 0) { 2594 tty->print_cr(" RSet is empty"); 2595 } else { 2596 hrrs->print(); 2597 } 2598 tty->print_cr("----------"); 2599 return false; 2600 } 2601 2602 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2603 tty->cr(); 2604 tty->print_cr("========================================"); 2605 tty->print_cr("%s", msg); 2606 tty->cr(); 2607 } 2608 2609 ~PrintRSetsClosure() { 2610 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2611 tty->print_cr("========================================"); 2612 tty->cr(); 2613 } 2614 }; 2615 2616 void G1CollectedHeap::print_cset_rsets() { 2617 PrintRSetsClosure cl("Printing CSet RSets"); 2618 collection_set_iterate_all(&cl); 2619 } 2620 2621 void G1CollectedHeap::print_all_rsets() { 2622 PrintRSetsClosure cl("Printing All RSets");; 2623 heap_region_iterate(&cl); 2624 } 2625 #endif // PRODUCT 2626 2627 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2628 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2629 } 2630 2631 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2632 2633 size_t eden_used_bytes = _eden.used_bytes(); 2634 size_t survivor_used_bytes = _survivor.used_bytes(); 2635 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2636 2637 size_t eden_capacity_bytes = 2638 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2639 2640 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2641 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2642 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2643 } 2644 2645 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2646 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2647 stats->unused(), stats->used(), stats->region_end_waste(), 2648 stats->regions_filled(), stats->direct_allocated(), 2649 stats->failure_used(), stats->failure_waste()); 2650 } 2651 2652 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2653 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2654 gc_tracer->report_gc_heap_summary(when, heap_summary); 2655 2656 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2657 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2658 } 2659 2660 G1CollectedHeap* G1CollectedHeap::heap() { 2661 CollectedHeap* heap = Universe::heap(); 2662 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2663 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2664 return (G1CollectedHeap*)heap; 2665 } 2666 2667 void G1CollectedHeap::gc_prologue(bool full) { 2668 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2669 2670 // This summary needs to be printed before incrementing total collections. 2671 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2672 2673 // Update common counters. 2674 increment_total_collections(full /* full gc */); 2675 if (full || collector_state()->in_initial_mark_gc()) { 2676 increment_old_marking_cycles_started(); 2677 } 2678 2679 // Fill TLAB's and such 2680 double start = os::elapsedTime(); 2681 ensure_parsability(true); 2682 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2683 } 2684 2685 void G1CollectedHeap::gc_epilogue(bool full) { 2686 // Update common counters. 2687 if (full) { 2688 // Update the number of full collections that have been completed. 2689 increment_old_marking_cycles_completed(false /* concurrent */); 2690 } 2691 2692 // We are at the end of the GC. Total collections has already been increased. 2693 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2694 2695 // FIXME: what is this about? 2696 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2697 // is set. 2698 #if COMPILER2_OR_JVMCI 2699 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2700 #endif 2701 2702 double start = os::elapsedTime(); 2703 resize_all_tlabs(); 2704 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2705 2706 MemoryService::track_memory_usage(); 2707 // We have just completed a GC. Update the soft reference 2708 // policy with the new heap occupancy 2709 Universe::update_heap_info_at_gc(); 2710 2711 // Print NUMA statistics. 2712 _numa->print_statistics(); 2713 } 2714 2715 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2716 LogTarget(Trace, gc, heap, verify) lt; 2717 2718 if (lt.is_enabled()) { 2719 LogStream ls(lt); 2720 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2721 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2722 heap_region_iterate(&cl); 2723 } 2724 } 2725 2726 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2727 uint gc_count_before, 2728 bool* succeeded, 2729 GCCause::Cause gc_cause) { 2730 assert_heap_not_locked_and_not_at_safepoint(); 2731 VM_G1CollectForAllocation op(word_size, 2732 gc_count_before, 2733 gc_cause, 2734 policy()->max_pause_time_ms()); 2735 VMThread::execute(&op); 2736 2737 HeapWord* result = op.result(); 2738 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2739 assert(result == NULL || ret_succeeded, 2740 "the result should be NULL if the VM did not succeed"); 2741 *succeeded = ret_succeeded; 2742 2743 assert_heap_not_locked(); 2744 return result; 2745 } 2746 2747 void G1CollectedHeap::do_concurrent_mark() { 2748 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2749 if (!_cm_thread->in_progress()) { 2750 _cm_thread->set_started(); 2751 CGC_lock->notify(); 2752 } 2753 } 2754 2755 size_t G1CollectedHeap::pending_card_num() { 2756 struct CountCardsClosure : public ThreadClosure { 2757 size_t _cards; 2758 CountCardsClosure() : _cards(0) {} 2759 virtual void do_thread(Thread* t) { 2760 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2761 } 2762 } count_from_threads; 2763 Threads::threads_do(&count_from_threads); 2764 2765 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2766 dcqs.verify_num_cards(); 2767 2768 return dcqs.num_cards() + count_from_threads._cards; 2769 } 2770 2771 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2772 // We don't nominate objects with many remembered set entries, on 2773 // the assumption that such objects are likely still live. 2774 HeapRegionRemSet* rem_set = r->rem_set(); 2775 2776 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2777 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2778 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2779 } 2780 2781 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2782 private: 2783 size_t _total_humongous; 2784 size_t _candidate_humongous; 2785 2786 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2787 assert(region->is_starts_humongous(), "Must start a humongous object"); 2788 2789 oop obj = oop(region->bottom()); 2790 2791 // Dead objects cannot be eager reclaim candidates. Due to class 2792 // unloading it is unsafe to query their classes so we return early. 2793 if (g1h->is_obj_dead(obj, region)) { 2794 return false; 2795 } 2796 2797 // If we do not have a complete remembered set for the region, then we can 2798 // not be sure that we have all references to it. 2799 if (!region->rem_set()->is_complete()) { 2800 return false; 2801 } 2802 // Candidate selection must satisfy the following constraints 2803 // while concurrent marking is in progress: 2804 // 2805 // * In order to maintain SATB invariants, an object must not be 2806 // reclaimed if it was allocated before the start of marking and 2807 // has not had its references scanned. Such an object must have 2808 // its references (including type metadata) scanned to ensure no 2809 // live objects are missed by the marking process. Objects 2810 // allocated after the start of concurrent marking don't need to 2811 // be scanned. 2812 // 2813 // * An object must not be reclaimed if it is on the concurrent 2814 // mark stack. Objects allocated after the start of concurrent 2815 // marking are never pushed on the mark stack. 2816 // 2817 // Nominating only objects allocated after the start of concurrent 2818 // marking is sufficient to meet both constraints. This may miss 2819 // some objects that satisfy the constraints, but the marking data 2820 // structures don't support efficiently performing the needed 2821 // additional tests or scrubbing of the mark stack. 2822 // 2823 // However, we presently only nominate is_typeArray() objects. 2824 // A humongous object containing references induces remembered 2825 // set entries on other regions. In order to reclaim such an 2826 // object, those remembered sets would need to be cleaned up. 2827 // 2828 // We also treat is_typeArray() objects specially, allowing them 2829 // to be reclaimed even if allocated before the start of 2830 // concurrent mark. For this we rely on mark stack insertion to 2831 // exclude is_typeArray() objects, preventing reclaiming an object 2832 // that is in the mark stack. We also rely on the metadata for 2833 // such objects to be built-in and so ensured to be kept live. 2834 // Frequent allocation and drop of large binary blobs is an 2835 // important use case for eager reclaim, and this special handling 2836 // may reduce needed headroom. 2837 2838 return obj->is_typeArray() && 2839 g1h->is_potential_eager_reclaim_candidate(region); 2840 } 2841 2842 public: 2843 RegisterRegionsWithRegionAttrTableClosure() 2844 : _total_humongous(0), 2845 _candidate_humongous(0) { 2846 } 2847 2848 virtual bool do_heap_region(HeapRegion* r) { 2849 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2850 2851 if (!r->is_starts_humongous()) { 2852 g1h->register_region_with_region_attr(r); 2853 return false; 2854 } 2855 2856 bool is_candidate = humongous_region_is_candidate(g1h, r); 2857 uint rindex = r->hrm_index(); 2858 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2859 if (is_candidate) { 2860 g1h->register_humongous_region_with_region_attr(rindex); 2861 _candidate_humongous++; 2862 // We will later handle the remembered sets of these regions. 2863 } else { 2864 g1h->register_region_with_region_attr(r); 2865 } 2866 _total_humongous++; 2867 2868 return false; 2869 } 2870 2871 size_t total_humongous() const { return _total_humongous; } 2872 size_t candidate_humongous() const { return _candidate_humongous; } 2873 }; 2874 2875 void G1CollectedHeap::register_regions_with_region_attr() { 2876 Ticks start = Ticks::now(); 2877 2878 RegisterRegionsWithRegionAttrTableClosure cl; 2879 heap_region_iterate(&cl); 2880 2881 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2882 cl.total_humongous(), 2883 cl.candidate_humongous()); 2884 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2885 } 2886 2887 #ifndef PRODUCT 2888 void G1CollectedHeap::verify_region_attr_remset_update() { 2889 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2890 public: 2891 virtual bool do_heap_region(HeapRegion* r) { 2892 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2893 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2894 assert(r->rem_set()->is_tracked() == needs_remset_update, 2895 "Region %u remset tracking status (%s) different to region attribute (%s)", 2896 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2897 return false; 2898 } 2899 } cl; 2900 heap_region_iterate(&cl); 2901 } 2902 #endif 2903 2904 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2905 public: 2906 bool do_heap_region(HeapRegion* hr) { 2907 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2908 hr->verify_rem_set(); 2909 } 2910 return false; 2911 } 2912 }; 2913 2914 uint G1CollectedHeap::num_task_queues() const { 2915 return _task_queues->size(); 2916 } 2917 2918 #if TASKQUEUE_STATS 2919 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2920 st->print_raw_cr("GC Task Stats"); 2921 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2922 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2923 } 2924 2925 void G1CollectedHeap::print_taskqueue_stats() const { 2926 if (!log_is_enabled(Trace, gc, task, stats)) { 2927 return; 2928 } 2929 Log(gc, task, stats) log; 2930 ResourceMark rm; 2931 LogStream ls(log.trace()); 2932 outputStream* st = &ls; 2933 2934 print_taskqueue_stats_hdr(st); 2935 2936 TaskQueueStats totals; 2937 const uint n = num_task_queues(); 2938 for (uint i = 0; i < n; ++i) { 2939 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2940 totals += task_queue(i)->stats; 2941 } 2942 st->print_raw("tot "); totals.print(st); st->cr(); 2943 2944 DEBUG_ONLY(totals.verify()); 2945 } 2946 2947 void G1CollectedHeap::reset_taskqueue_stats() { 2948 const uint n = num_task_queues(); 2949 for (uint i = 0; i < n; ++i) { 2950 task_queue(i)->stats.reset(); 2951 } 2952 } 2953 #endif // TASKQUEUE_STATS 2954 2955 void G1CollectedHeap::wait_for_root_region_scanning() { 2956 double scan_wait_start = os::elapsedTime(); 2957 // We have to wait until the CM threads finish scanning the 2958 // root regions as it's the only way to ensure that all the 2959 // objects on them have been correctly scanned before we start 2960 // moving them during the GC. 2961 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2962 double wait_time_ms = 0.0; 2963 if (waited) { 2964 double scan_wait_end = os::elapsedTime(); 2965 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2966 } 2967 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2968 } 2969 2970 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2971 private: 2972 G1HRPrinter* _hr_printer; 2973 public: 2974 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2975 2976 virtual bool do_heap_region(HeapRegion* r) { 2977 _hr_printer->cset(r); 2978 return false; 2979 } 2980 }; 2981 2982 void G1CollectedHeap::start_new_collection_set() { 2983 double start = os::elapsedTime(); 2984 2985 collection_set()->start_incremental_building(); 2986 2987 clear_region_attr(); 2988 2989 guarantee(_eden.length() == 0, "eden should have been cleared"); 2990 policy()->transfer_survivors_to_cset(survivor()); 2991 2992 // We redo the verification but now wrt to the new CSet which 2993 // has just got initialized after the previous CSet was freed. 2994 _cm->verify_no_collection_set_oops(); 2995 2996 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2997 } 2998 2999 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 3000 3001 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 3002 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 3003 collection_set()->optional_region_length()); 3004 3005 _cm->verify_no_collection_set_oops(); 3006 3007 if (_hr_printer.is_active()) { 3008 G1PrintCollectionSetClosure cl(&_hr_printer); 3009 _collection_set.iterate(&cl); 3010 _collection_set.iterate_optional(&cl); 3011 } 3012 } 3013 3014 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 3015 if (collector_state()->in_initial_mark_gc()) { 3016 return G1HeapVerifier::G1VerifyConcurrentStart; 3017 } else if (collector_state()->in_young_only_phase()) { 3018 return G1HeapVerifier::G1VerifyYoungNormal; 3019 } else { 3020 return G1HeapVerifier::G1VerifyMixed; 3021 } 3022 } 3023 3024 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 3025 if (VerifyRememberedSets) { 3026 log_info(gc, verify)("[Verifying RemSets before GC]"); 3027 VerifyRegionRemSetClosure v_cl; 3028 heap_region_iterate(&v_cl); 3029 } 3030 _verifier->verify_before_gc(type); 3031 _verifier->check_bitmaps("GC Start"); 3032 verify_numa_regions("GC Start"); 3033 } 3034 3035 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 3036 if (VerifyRememberedSets) { 3037 log_info(gc, verify)("[Verifying RemSets after GC]"); 3038 VerifyRegionRemSetClosure v_cl; 3039 heap_region_iterate(&v_cl); 3040 } 3041 _verifier->verify_after_gc(type); 3042 _verifier->check_bitmaps("GC End"); 3043 verify_numa_regions("GC End"); 3044 } 3045 3046 void G1CollectedHeap::expand_heap_after_young_collection(){ 3047 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3048 if (expand_bytes > 0) { 3049 // No need for an ergo logging here, 3050 // expansion_amount() does this when it returns a value > 0. 3051 double expand_ms; 3052 if (!expand(expand_bytes, _workers, &expand_ms)) { 3053 // We failed to expand the heap. Cannot do anything about it. 3054 } 3055 phase_times()->record_expand_heap_time(expand_ms); 3056 } 3057 } 3058 3059 const char* G1CollectedHeap::young_gc_name() const { 3060 if (collector_state()->in_initial_mark_gc()) { 3061 return "Pause Young (Concurrent Start)"; 3062 } else if (collector_state()->in_young_only_phase()) { 3063 if (collector_state()->in_young_gc_before_mixed()) { 3064 return "Pause Young (Prepare Mixed)"; 3065 } else { 3066 return "Pause Young (Normal)"; 3067 } 3068 } else { 3069 return "Pause Young (Mixed)"; 3070 } 3071 } 3072 3073 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3074 assert_at_safepoint_on_vm_thread(); 3075 guarantee(!is_gc_active(), "collection is not reentrant"); 3076 3077 if (GCLocker::check_active_before_gc()) { 3078 return false; 3079 } 3080 3081 GCIdMark gc_id_mark; 3082 3083 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3084 ResourceMark rm; 3085 3086 policy()->note_gc_start(); 3087 3088 _gc_timer_stw->register_gc_start(); 3089 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3090 3091 wait_for_root_region_scanning(); 3092 3093 print_heap_before_gc(); 3094 print_heap_regions(); 3095 trace_heap_before_gc(_gc_tracer_stw); 3096 3097 _verifier->verify_region_sets_optional(); 3098 _verifier->verify_dirty_young_regions(); 3099 3100 // We should not be doing initial mark unless the conc mark thread is running 3101 if (!_cm_thread->should_terminate()) { 3102 // This call will decide whether this pause is an initial-mark 3103 // pause. If it is, in_initial_mark_gc() will return true 3104 // for the duration of this pause. 3105 policy()->decide_on_conc_mark_initiation(); 3106 } 3107 3108 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3109 assert(!collector_state()->in_initial_mark_gc() || 3110 collector_state()->in_young_only_phase(), "sanity"); 3111 // We also do not allow mixed GCs during marking. 3112 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 3113 3114 // Record whether this pause is an initial mark. When the current 3115 // thread has completed its logging output and it's safe to signal 3116 // the CM thread, the flag's value in the policy has been reset. 3117 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 3118 if (should_start_conc_mark) { 3119 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3120 } 3121 3122 // Inner scope for scope based logging, timers, and stats collection 3123 { 3124 G1EvacuationInfo evacuation_info; 3125 3126 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3127 3128 GCTraceCPUTime tcpu; 3129 3130 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3131 3132 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3133 workers()->active_workers(), 3134 Threads::number_of_non_daemon_threads()); 3135 active_workers = workers()->update_active_workers(active_workers); 3136 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3137 3138 G1MonitoringScope ms(g1mm(), 3139 false /* full_gc */, 3140 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3141 3142 G1HeapTransition heap_transition(this); 3143 size_t heap_used_bytes_before_gc = used(); 3144 3145 { 3146 IsGCActiveMark x; 3147 3148 gc_prologue(false); 3149 3150 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3151 verify_before_young_collection(verify_type); 3152 3153 { 3154 // The elapsed time induced by the start time below deliberately elides 3155 // the possible verification above. 3156 double sample_start_time_sec = os::elapsedTime(); 3157 3158 // Please see comment in g1CollectedHeap.hpp and 3159 // G1CollectedHeap::ref_processing_init() to see how 3160 // reference processing currently works in G1. 3161 _ref_processor_stw->enable_discovery(); 3162 3163 // We want to temporarily turn off discovery by the 3164 // CM ref processor, if necessary, and turn it back on 3165 // on again later if we do. Using a scoped 3166 // NoRefDiscovery object will do this. 3167 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3168 3169 policy()->record_collection_pause_start(sample_start_time_sec); 3170 3171 // Forget the current allocation region (we might even choose it to be part 3172 // of the collection set!). 3173 _allocator->release_mutator_alloc_regions(); 3174 3175 calculate_collection_set(evacuation_info, target_pause_time_ms); 3176 3177 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3178 G1ParScanThreadStateSet per_thread_states(this, 3179 &rdcqs, 3180 workers()->active_workers(), 3181 collection_set()->young_region_length(), 3182 collection_set()->optional_region_length()); 3183 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3184 3185 // Actually do the work... 3186 evacuate_initial_collection_set(&per_thread_states); 3187 3188 if (_collection_set.optional_region_length() != 0) { 3189 evacuate_optional_collection_set(&per_thread_states); 3190 } 3191 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3192 3193 start_new_collection_set(); 3194 3195 _survivor_evac_stats.adjust_desired_plab_sz(); 3196 _old_evac_stats.adjust_desired_plab_sz(); 3197 3198 if (should_start_conc_mark) { 3199 // We have to do this before we notify the CM threads that 3200 // they can start working to make sure that all the 3201 // appropriate initialization is done on the CM object. 3202 concurrent_mark()->post_initial_mark(); 3203 // Note that we don't actually trigger the CM thread at 3204 // this point. We do that later when we're sure that 3205 // the current thread has completed its logging output. 3206 } 3207 3208 allocate_dummy_regions(); 3209 3210 _allocator->init_mutator_alloc_regions(); 3211 3212 expand_heap_after_young_collection(); 3213 3214 double sample_end_time_sec = os::elapsedTime(); 3215 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3216 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc); 3217 } 3218 3219 verify_after_young_collection(verify_type); 3220 3221 #ifdef TRACESPINNING 3222 ParallelTaskTerminator::print_termination_counts(); 3223 #endif 3224 3225 gc_epilogue(false); 3226 } 3227 3228 // Print the remainder of the GC log output. 3229 if (evacuation_failed()) { 3230 log_info(gc)("To-space exhausted"); 3231 } 3232 3233 policy()->print_phases(); 3234 heap_transition.print(); 3235 3236 _hrm->verify_optional(); 3237 _verifier->verify_region_sets_optional(); 3238 3239 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3240 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3241 3242 print_heap_after_gc(); 3243 print_heap_regions(); 3244 trace_heap_after_gc(_gc_tracer_stw); 3245 3246 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3247 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3248 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3249 // before any GC notifications are raised. 3250 g1mm()->update_sizes(); 3251 3252 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3253 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3254 _gc_timer_stw->register_gc_end(); 3255 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3256 } 3257 // It should now be safe to tell the concurrent mark thread to start 3258 // without its logging output interfering with the logging output 3259 // that came from the pause. 3260 3261 if (should_start_conc_mark) { 3262 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3263 // thread(s) could be running concurrently with us. Make sure that anything 3264 // after this point does not assume that we are the only GC thread running. 3265 // Note: of course, the actual marking work will not start until the safepoint 3266 // itself is released in SuspendibleThreadSet::desynchronize(). 3267 do_concurrent_mark(); 3268 } 3269 3270 return true; 3271 } 3272 3273 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3274 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3275 workers()->run_task(&rsfp_task); 3276 } 3277 3278 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3279 double remove_self_forwards_start = os::elapsedTime(); 3280 3281 remove_self_forwarding_pointers(rdcqs); 3282 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3283 _preserved_marks_set.restore(&task_executor); 3284 3285 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3286 } 3287 3288 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3289 if (!_evacuation_failed) { 3290 _evacuation_failed = true; 3291 } 3292 3293 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3294 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3295 } 3296 3297 bool G1ParEvacuateFollowersClosure::offer_termination() { 3298 EventGCPhaseParallel event; 3299 G1ParScanThreadState* const pss = par_scan_state(); 3300 start_term_time(); 3301 const bool res = terminator()->offer_termination(); 3302 end_term_time(); 3303 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3304 return res; 3305 } 3306 3307 void G1ParEvacuateFollowersClosure::do_void() { 3308 EventGCPhaseParallel event; 3309 G1ParScanThreadState* const pss = par_scan_state(); 3310 pss->trim_queue(); 3311 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3312 do { 3313 EventGCPhaseParallel event; 3314 pss->steal_and_trim_queue(queues()); 3315 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3316 } while (!offer_termination()); 3317 } 3318 3319 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3320 bool class_unloading_occurred) { 3321 uint num_workers = workers()->active_workers(); 3322 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3323 workers()->run_task(&unlink_task); 3324 } 3325 3326 // Clean string dedup data structures. 3327 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3328 // record the durations of the phases. Hence the almost-copy. 3329 class G1StringDedupCleaningTask : public AbstractGangTask { 3330 BoolObjectClosure* _is_alive; 3331 OopClosure* _keep_alive; 3332 G1GCPhaseTimes* _phase_times; 3333 3334 public: 3335 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3336 OopClosure* keep_alive, 3337 G1GCPhaseTimes* phase_times) : 3338 AbstractGangTask("Partial Cleaning Task"), 3339 _is_alive(is_alive), 3340 _keep_alive(keep_alive), 3341 _phase_times(phase_times) 3342 { 3343 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3344 StringDedup::gc_prologue(true); 3345 } 3346 3347 ~G1StringDedupCleaningTask() { 3348 StringDedup::gc_epilogue(); 3349 } 3350 3351 void work(uint worker_id) { 3352 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3353 { 3354 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3355 StringDedupQueue::unlink_or_oops_do(&cl); 3356 } 3357 { 3358 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3359 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3360 } 3361 } 3362 }; 3363 3364 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3365 OopClosure* keep_alive, 3366 G1GCPhaseTimes* phase_times) { 3367 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3368 workers()->run_task(&cl); 3369 } 3370 3371 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3372 private: 3373 G1RedirtyCardsQueueSet* _qset; 3374 G1CollectedHeap* _g1h; 3375 BufferNode* volatile _nodes; 3376 3377 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3378 size_t buffer_size = _qset->buffer_size(); 3379 BufferNode* next = Atomic::load(&_nodes); 3380 while (next != NULL) { 3381 BufferNode* node = next; 3382 next = Atomic::cmpxchg(node->next(), &_nodes, node); 3383 if (next == node) { 3384 cl->apply_to_buffer(node, buffer_size, worker_id); 3385 next = node->next(); 3386 } 3387 } 3388 } 3389 3390 public: 3391 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3392 AbstractGangTask("Redirty Cards"), 3393 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3394 3395 virtual void work(uint worker_id) { 3396 G1GCPhaseTimes* p = _g1h->phase_times(); 3397 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3398 3399 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3400 par_apply(&cl, worker_id); 3401 3402 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3403 } 3404 }; 3405 3406 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3407 double redirty_logged_cards_start = os::elapsedTime(); 3408 3409 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3410 workers()->run_task(&redirty_task); 3411 3412 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3413 dcq.merge_bufferlists(rdcqs); 3414 3415 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3416 } 3417 3418 // Weak Reference Processing support 3419 3420 bool G1STWIsAliveClosure::do_object_b(oop p) { 3421 // An object is reachable if it is outside the collection set, 3422 // or is inside and copied. 3423 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3424 } 3425 3426 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3427 assert(obj != NULL, "must not be NULL"); 3428 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3429 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3430 // may falsely indicate that this is not the case here: however the collection set only 3431 // contains old regions when concurrent mark is not running. 3432 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3433 } 3434 3435 // Non Copying Keep Alive closure 3436 class G1KeepAliveClosure: public OopClosure { 3437 G1CollectedHeap*_g1h; 3438 public: 3439 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3440 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3441 void do_oop(oop* p) { 3442 oop obj = *p; 3443 assert(obj != NULL, "the caller should have filtered out NULL values"); 3444 3445 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3446 if (!region_attr.is_in_cset_or_humongous()) { 3447 return; 3448 } 3449 if (region_attr.is_in_cset()) { 3450 assert( obj->is_forwarded(), "invariant" ); 3451 *p = obj->forwardee(); 3452 } else { 3453 assert(!obj->is_forwarded(), "invariant" ); 3454 assert(region_attr.is_humongous(), 3455 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3456 _g1h->set_humongous_is_live(obj); 3457 } 3458 } 3459 }; 3460 3461 // Copying Keep Alive closure - can be called from both 3462 // serial and parallel code as long as different worker 3463 // threads utilize different G1ParScanThreadState instances 3464 // and different queues. 3465 3466 class G1CopyingKeepAliveClosure: public OopClosure { 3467 G1CollectedHeap* _g1h; 3468 G1ParScanThreadState* _par_scan_state; 3469 3470 public: 3471 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3472 G1ParScanThreadState* pss): 3473 _g1h(g1h), 3474 _par_scan_state(pss) 3475 {} 3476 3477 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3478 virtual void do_oop( oop* p) { do_oop_work(p); } 3479 3480 template <class T> void do_oop_work(T* p) { 3481 oop obj = RawAccess<>::oop_load(p); 3482 3483 if (_g1h->is_in_cset_or_humongous(obj)) { 3484 // If the referent object has been forwarded (either copied 3485 // to a new location or to itself in the event of an 3486 // evacuation failure) then we need to update the reference 3487 // field and, if both reference and referent are in the G1 3488 // heap, update the RSet for the referent. 3489 // 3490 // If the referent has not been forwarded then we have to keep 3491 // it alive by policy. Therefore we have copy the referent. 3492 // 3493 // When the queue is drained (after each phase of reference processing) 3494 // the object and it's followers will be copied, the reference field set 3495 // to point to the new location, and the RSet updated. 3496 _par_scan_state->push_on_queue(p); 3497 } 3498 } 3499 }; 3500 3501 // Serial drain queue closure. Called as the 'complete_gc' 3502 // closure for each discovered list in some of the 3503 // reference processing phases. 3504 3505 class G1STWDrainQueueClosure: public VoidClosure { 3506 protected: 3507 G1CollectedHeap* _g1h; 3508 G1ParScanThreadState* _par_scan_state; 3509 3510 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3511 3512 public: 3513 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3514 _g1h(g1h), 3515 _par_scan_state(pss) 3516 { } 3517 3518 void do_void() { 3519 G1ParScanThreadState* const pss = par_scan_state(); 3520 pss->trim_queue(); 3521 } 3522 }; 3523 3524 // Parallel Reference Processing closures 3525 3526 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3527 // processing during G1 evacuation pauses. 3528 3529 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3530 private: 3531 G1CollectedHeap* _g1h; 3532 G1ParScanThreadStateSet* _pss; 3533 RefToScanQueueSet* _queues; 3534 WorkGang* _workers; 3535 3536 public: 3537 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3538 G1ParScanThreadStateSet* per_thread_states, 3539 WorkGang* workers, 3540 RefToScanQueueSet *task_queues) : 3541 _g1h(g1h), 3542 _pss(per_thread_states), 3543 _queues(task_queues), 3544 _workers(workers) 3545 { 3546 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3547 } 3548 3549 // Executes the given task using concurrent marking worker threads. 3550 virtual void execute(ProcessTask& task, uint ergo_workers); 3551 }; 3552 3553 // Gang task for possibly parallel reference processing 3554 3555 class G1STWRefProcTaskProxy: public AbstractGangTask { 3556 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3557 ProcessTask& _proc_task; 3558 G1CollectedHeap* _g1h; 3559 G1ParScanThreadStateSet* _pss; 3560 RefToScanQueueSet* _task_queues; 3561 ParallelTaskTerminator* _terminator; 3562 3563 public: 3564 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3565 G1CollectedHeap* g1h, 3566 G1ParScanThreadStateSet* per_thread_states, 3567 RefToScanQueueSet *task_queues, 3568 ParallelTaskTerminator* terminator) : 3569 AbstractGangTask("Process reference objects in parallel"), 3570 _proc_task(proc_task), 3571 _g1h(g1h), 3572 _pss(per_thread_states), 3573 _task_queues(task_queues), 3574 _terminator(terminator) 3575 {} 3576 3577 virtual void work(uint worker_id) { 3578 // The reference processing task executed by a single worker. 3579 ResourceMark rm; 3580 HandleMark hm; 3581 3582 G1STWIsAliveClosure is_alive(_g1h); 3583 3584 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3585 pss->set_ref_discoverer(NULL); 3586 3587 // Keep alive closure. 3588 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3589 3590 // Complete GC closure 3591 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3592 3593 // Call the reference processing task's work routine. 3594 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3595 3596 // Note we cannot assert that the refs array is empty here as not all 3597 // of the processing tasks (specifically phase2 - pp2_work) execute 3598 // the complete_gc closure (which ordinarily would drain the queue) so 3599 // the queue may not be empty. 3600 } 3601 }; 3602 3603 // Driver routine for parallel reference processing. 3604 // Creates an instance of the ref processing gang 3605 // task and has the worker threads execute it. 3606 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3607 assert(_workers != NULL, "Need parallel worker threads."); 3608 3609 assert(_workers->active_workers() >= ergo_workers, 3610 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3611 ergo_workers, _workers->active_workers()); 3612 TaskTerminator terminator(ergo_workers, _queues); 3613 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3614 3615 _workers->run_task(&proc_task_proxy, ergo_workers); 3616 } 3617 3618 // End of weak reference support closures 3619 3620 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3621 double ref_proc_start = os::elapsedTime(); 3622 3623 ReferenceProcessor* rp = _ref_processor_stw; 3624 assert(rp->discovery_enabled(), "should have been enabled"); 3625 3626 // Closure to test whether a referent is alive. 3627 G1STWIsAliveClosure is_alive(this); 3628 3629 // Even when parallel reference processing is enabled, the processing 3630 // of JNI refs is serial and performed serially by the current thread 3631 // rather than by a worker. The following PSS will be used for processing 3632 // JNI refs. 3633 3634 // Use only a single queue for this PSS. 3635 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3636 pss->set_ref_discoverer(NULL); 3637 assert(pss->queue_is_empty(), "pre-condition"); 3638 3639 // Keep alive closure. 3640 G1CopyingKeepAliveClosure keep_alive(this, pss); 3641 3642 // Serial Complete GC closure 3643 G1STWDrainQueueClosure drain_queue(this, pss); 3644 3645 // Setup the soft refs policy... 3646 rp->setup_policy(false); 3647 3648 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3649 3650 ReferenceProcessorStats stats; 3651 if (!rp->processing_is_mt()) { 3652 // Serial reference processing... 3653 stats = rp->process_discovered_references(&is_alive, 3654 &keep_alive, 3655 &drain_queue, 3656 NULL, 3657 pt); 3658 } else { 3659 uint no_of_gc_workers = workers()->active_workers(); 3660 3661 // Parallel reference processing 3662 assert(no_of_gc_workers <= rp->max_num_queues(), 3663 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3664 no_of_gc_workers, rp->max_num_queues()); 3665 3666 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3667 stats = rp->process_discovered_references(&is_alive, 3668 &keep_alive, 3669 &drain_queue, 3670 &par_task_executor, 3671 pt); 3672 } 3673 3674 _gc_tracer_stw->report_gc_reference_stats(stats); 3675 3676 // We have completed copying any necessary live referent objects. 3677 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3678 3679 make_pending_list_reachable(); 3680 3681 assert(!rp->discovery_enabled(), "Postcondition"); 3682 rp->verify_no_references_recorded(); 3683 3684 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3685 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3686 } 3687 3688 void G1CollectedHeap::make_pending_list_reachable() { 3689 if (collector_state()->in_initial_mark_gc()) { 3690 oop pll_head = Universe::reference_pending_list(); 3691 if (pll_head != NULL) { 3692 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3693 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3694 } 3695 } 3696 } 3697 3698 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3699 double merge_pss_time_start = os::elapsedTime(); 3700 per_thread_states->flush(); 3701 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3702 } 3703 3704 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3705 _expand_heap_after_alloc_failure = true; 3706 _evacuation_failed = false; 3707 3708 // Disable the hot card cache. 3709 _hot_card_cache->reset_hot_cache_claimed_index(); 3710 _hot_card_cache->set_use_cache(false); 3711 3712 // Initialize the GC alloc regions. 3713 _allocator->init_gc_alloc_regions(evacuation_info); 3714 3715 { 3716 Ticks start = Ticks::now(); 3717 rem_set()->prepare_for_scan_heap_roots(); 3718 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3719 } 3720 3721 register_regions_with_region_attr(); 3722 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3723 3724 _preserved_marks_set.assert_empty(); 3725 3726 #if COMPILER2_OR_JVMCI 3727 DerivedPointerTable::clear(); 3728 #endif 3729 3730 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3731 if (collector_state()->in_initial_mark_gc()) { 3732 concurrent_mark()->pre_initial_mark(); 3733 3734 double start_clear_claimed_marks = os::elapsedTime(); 3735 3736 ClassLoaderDataGraph::clear_claimed_marks(); 3737 3738 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3739 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3740 } 3741 3742 // Should G1EvacuationFailureALot be in effect for this GC? 3743 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3744 } 3745 3746 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3747 protected: 3748 G1CollectedHeap* _g1h; 3749 G1ParScanThreadStateSet* _per_thread_states; 3750 RefToScanQueueSet* _task_queues; 3751 TaskTerminator _terminator; 3752 uint _num_workers; 3753 3754 void evacuate_live_objects(G1ParScanThreadState* pss, 3755 uint worker_id, 3756 G1GCPhaseTimes::GCParPhases objcopy_phase, 3757 G1GCPhaseTimes::GCParPhases termination_phase) { 3758 G1GCPhaseTimes* p = _g1h->phase_times(); 3759 3760 Ticks start = Ticks::now(); 3761 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase); 3762 cl.do_void(); 3763 3764 assert(pss->queue_is_empty(), "should be empty"); 3765 3766 Tickspan evac_time = (Ticks::now() - start); 3767 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3768 3769 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste); 3770 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste); 3771 3772 if (termination_phase == G1GCPhaseTimes::Termination) { 3773 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3774 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3775 } else { 3776 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3777 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3778 } 3779 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3780 } 3781 3782 virtual void start_work(uint worker_id) { } 3783 3784 virtual void end_work(uint worker_id) { } 3785 3786 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3787 3788 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3789 3790 public: 3791 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3792 AbstractGangTask(name), 3793 _g1h(G1CollectedHeap::heap()), 3794 _per_thread_states(per_thread_states), 3795 _task_queues(task_queues), 3796 _terminator(num_workers, _task_queues), 3797 _num_workers(num_workers) 3798 { } 3799 3800 void work(uint worker_id) { 3801 start_work(worker_id); 3802 3803 { 3804 ResourceMark rm; 3805 HandleMark hm; 3806 3807 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3808 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3809 3810 scan_roots(pss, worker_id); 3811 evacuate_live_objects(pss, worker_id); 3812 } 3813 3814 end_work(worker_id); 3815 } 3816 }; 3817 3818 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3819 G1RootProcessor* _root_processor; 3820 3821 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3822 _root_processor->evacuate_roots(pss, worker_id); 3823 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3824 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3825 } 3826 3827 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3828 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3829 } 3830 3831 void start_work(uint worker_id) { 3832 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3833 } 3834 3835 void end_work(uint worker_id) { 3836 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3837 } 3838 3839 public: 3840 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3841 G1ParScanThreadStateSet* per_thread_states, 3842 RefToScanQueueSet* task_queues, 3843 G1RootProcessor* root_processor, 3844 uint num_workers) : 3845 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3846 _root_processor(root_processor) 3847 { } 3848 }; 3849 3850 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3851 G1GCPhaseTimes* p = phase_times(); 3852 3853 { 3854 Ticks start = Ticks::now(); 3855 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3856 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3857 } 3858 3859 Tickspan task_time; 3860 const uint num_workers = workers()->active_workers(); 3861 3862 Ticks start_processing = Ticks::now(); 3863 { 3864 G1RootProcessor root_processor(this, num_workers); 3865 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3866 task_time = run_task(&g1_par_task); 3867 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3868 // To extract its code root fixup time we measure total time of this scope and 3869 // subtract from the time the WorkGang task took. 3870 } 3871 Tickspan total_processing = Ticks::now() - start_processing; 3872 3873 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3874 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3875 } 3876 3877 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3878 3879 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3880 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3881 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3882 } 3883 3884 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3885 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3886 } 3887 3888 public: 3889 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3890 RefToScanQueueSet* queues, 3891 uint num_workers) : 3892 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3893 } 3894 }; 3895 3896 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3897 class G1MarkScope : public MarkScope { }; 3898 3899 Tickspan task_time; 3900 3901 Ticks start_processing = Ticks::now(); 3902 { 3903 G1MarkScope code_mark_scope; 3904 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3905 task_time = run_task(&task); 3906 // See comment in evacuate_collection_set() for the reason of the scope. 3907 } 3908 Tickspan total_processing = Ticks::now() - start_processing; 3909 3910 G1GCPhaseTimes* p = phase_times(); 3911 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3912 } 3913 3914 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3915 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3916 3917 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3918 3919 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3920 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3921 3922 if (time_left_ms < 0 || 3923 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3924 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3925 _collection_set.optional_region_length(), time_left_ms); 3926 break; 3927 } 3928 3929 { 3930 Ticks start = Ticks::now(); 3931 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3932 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3933 } 3934 3935 { 3936 Ticks start = Ticks::now(); 3937 evacuate_next_optional_regions(per_thread_states); 3938 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3939 } 3940 } 3941 3942 _collection_set.abandon_optional_collection_set(per_thread_states); 3943 } 3944 3945 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3946 G1RedirtyCardsQueueSet* rdcqs, 3947 G1ParScanThreadStateSet* per_thread_states) { 3948 rem_set()->cleanup_after_scan_heap_roots(); 3949 3950 // Process any discovered reference objects - we have 3951 // to do this _before_ we retire the GC alloc regions 3952 // as we may have to copy some 'reachable' referent 3953 // objects (and their reachable sub-graphs) that were 3954 // not copied during the pause. 3955 process_discovered_references(per_thread_states); 3956 3957 G1STWIsAliveClosure is_alive(this); 3958 G1KeepAliveClosure keep_alive(this); 3959 3960 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3961 phase_times()->weak_phase_times()); 3962 3963 if (G1StringDedup::is_enabled()) { 3964 double string_dedup_time_ms = os::elapsedTime(); 3965 3966 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3967 3968 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3969 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3970 } 3971 3972 _allocator->release_gc_alloc_regions(evacuation_info); 3973 3974 if (evacuation_failed()) { 3975 restore_after_evac_failure(rdcqs); 3976 3977 // Reset the G1EvacuationFailureALot counters and flags 3978 NOT_PRODUCT(reset_evacuation_should_fail();) 3979 3980 double recalculate_used_start = os::elapsedTime(); 3981 set_used(recalculate_used()); 3982 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3983 3984 if (_archive_allocator != NULL) { 3985 _archive_allocator->clear_used(); 3986 } 3987 for (uint i = 0; i < ParallelGCThreads; i++) { 3988 if (_evacuation_failed_info_array[i].has_failed()) { 3989 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3990 } 3991 } 3992 } else { 3993 // The "used" of the the collection set have already been subtracted 3994 // when they were freed. Add in the bytes evacuated. 3995 increase_used(policy()->bytes_copied_during_gc()); 3996 } 3997 3998 _preserved_marks_set.assert_empty(); 3999 4000 merge_per_thread_state_info(per_thread_states); 4001 4002 // Reset and re-enable the hot card cache. 4003 // Note the counts for the cards in the regions in the 4004 // collection set are reset when the collection set is freed. 4005 _hot_card_cache->reset_hot_cache(); 4006 _hot_card_cache->set_use_cache(true); 4007 4008 purge_code_root_memory(); 4009 4010 redirty_logged_cards(rdcqs); 4011 4012 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4013 4014 eagerly_reclaim_humongous_regions(); 4015 4016 record_obj_copy_mem_stats(); 4017 4018 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4019 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 4020 4021 #if COMPILER2_OR_JVMCI 4022 double start = os::elapsedTime(); 4023 DerivedPointerTable::update_pointers(); 4024 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4025 #endif 4026 policy()->print_age_table(); 4027 } 4028 4029 void G1CollectedHeap::record_obj_copy_mem_stats() { 4030 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4031 4032 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4033 create_g1_evac_summary(&_old_evac_stats)); 4034 } 4035 4036 void G1CollectedHeap::free_region(HeapRegion* hr, 4037 FreeRegionList* free_list, 4038 bool skip_remset, 4039 bool skip_hot_card_cache, 4040 bool locked) { 4041 assert(!hr->is_free(), "the region should not be free"); 4042 assert(!hr->is_empty(), "the region should not be empty"); 4043 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4044 assert(free_list != NULL, "pre-condition"); 4045 4046 if (G1VerifyBitmaps) { 4047 MemRegion mr(hr->bottom(), hr->end()); 4048 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4049 } 4050 4051 // Clear the card counts for this region. 4052 // Note: we only need to do this if the region is not young 4053 // (since we don't refine cards in young regions). 4054 if (!skip_hot_card_cache && !hr->is_young()) { 4055 _hot_card_cache->reset_card_counts(hr); 4056 } 4057 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4058 _policy->remset_tracker()->update_at_free(hr); 4059 free_list->add_ordered(hr); 4060 } 4061 4062 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4063 FreeRegionList* free_list) { 4064 assert(hr->is_humongous(), "this is only for humongous regions"); 4065 assert(free_list != NULL, "pre-condition"); 4066 hr->clear_humongous(); 4067 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 4068 } 4069 4070 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4071 const uint humongous_regions_removed) { 4072 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4073 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4074 _old_set.bulk_remove(old_regions_removed); 4075 _humongous_set.bulk_remove(humongous_regions_removed); 4076 } 4077 4078 } 4079 4080 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4081 assert(list != NULL, "list can't be null"); 4082 if (!list->is_empty()) { 4083 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4084 _hrm->insert_list_into_free_list(list); 4085 } 4086 } 4087 4088 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4089 decrease_used(bytes); 4090 } 4091 4092 class G1FreeCollectionSetTask : public AbstractGangTask { 4093 private: 4094 4095 // Closure applied to all regions in the collection set to do work that needs to 4096 // be done serially in a single thread. 4097 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4098 private: 4099 G1EvacuationInfo* _evacuation_info; 4100 const size_t* _surviving_young_words; 4101 4102 // Bytes used in successfully evacuated regions before the evacuation. 4103 size_t _before_used_bytes; 4104 // Bytes used in unsucessfully evacuated regions before the evacuation 4105 size_t _after_used_bytes; 4106 4107 size_t _bytes_allocated_in_old_since_last_gc; 4108 4109 size_t _failure_used_words; 4110 size_t _failure_waste_words; 4111 4112 FreeRegionList _local_free_list; 4113 public: 4114 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4115 HeapRegionClosure(), 4116 _evacuation_info(evacuation_info), 4117 _surviving_young_words(surviving_young_words), 4118 _before_used_bytes(0), 4119 _after_used_bytes(0), 4120 _bytes_allocated_in_old_since_last_gc(0), 4121 _failure_used_words(0), 4122 _failure_waste_words(0), 4123 _local_free_list("Local Region List for CSet Freeing") { 4124 } 4125 4126 virtual bool do_heap_region(HeapRegion* r) { 4127 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4128 4129 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4130 g1h->clear_region_attr(r); 4131 4132 if (r->is_young()) { 4133 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(), 4134 "Young index %u is wrong for region %u of type %s with %u young regions", 4135 r->young_index_in_cset(), 4136 r->hrm_index(), 4137 r->get_type_str(), 4138 g1h->collection_set()->young_region_length()); 4139 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4140 r->record_surv_words_in_group(words_survived); 4141 } 4142 4143 if (!r->evacuation_failed()) { 4144 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4145 _before_used_bytes += r->used(); 4146 g1h->free_region(r, 4147 &_local_free_list, 4148 true, /* skip_remset */ 4149 true, /* skip_hot_card_cache */ 4150 true /* locked */); 4151 } else { 4152 r->uninstall_surv_rate_group(); 4153 r->clear_young_index_in_cset(); 4154 r->set_evacuation_failed(false); 4155 // When moving a young gen region to old gen, we "allocate" that whole region 4156 // there. This is in addition to any already evacuated objects. Notify the 4157 // policy about that. 4158 // Old gen regions do not cause an additional allocation: both the objects 4159 // still in the region and the ones already moved are accounted for elsewhere. 4160 if (r->is_young()) { 4161 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4162 } 4163 // The region is now considered to be old. 4164 r->set_old(); 4165 // Do some allocation statistics accounting. Regions that failed evacuation 4166 // are always made old, so there is no need to update anything in the young 4167 // gen statistics, but we need to update old gen statistics. 4168 size_t used_words = r->marked_bytes() / HeapWordSize; 4169 4170 _failure_used_words += used_words; 4171 _failure_waste_words += HeapRegion::GrainWords - used_words; 4172 4173 g1h->old_set_add(r); 4174 _after_used_bytes += r->used(); 4175 } 4176 return false; 4177 } 4178 4179 void complete_work() { 4180 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4181 4182 _evacuation_info->set_regions_freed(_local_free_list.length()); 4183 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4184 4185 g1h->prepend_to_freelist(&_local_free_list); 4186 g1h->decrement_summary_bytes(_before_used_bytes); 4187 4188 G1Policy* policy = g1h->policy(); 4189 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4190 4191 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4192 } 4193 }; 4194 4195 G1CollectionSet* _collection_set; 4196 G1SerialFreeCollectionSetClosure _cl; 4197 const size_t* _surviving_young_words; 4198 4199 size_t _rs_length; 4200 4201 volatile jint _serial_work_claim; 4202 4203 struct WorkItem { 4204 uint region_idx; 4205 bool is_young; 4206 bool evacuation_failed; 4207 4208 WorkItem(HeapRegion* r) { 4209 region_idx = r->hrm_index(); 4210 is_young = r->is_young(); 4211 evacuation_failed = r->evacuation_failed(); 4212 } 4213 }; 4214 4215 volatile size_t _parallel_work_claim; 4216 size_t _num_work_items; 4217 WorkItem* _work_items; 4218 4219 void do_serial_work() { 4220 // Need to grab the lock to be allowed to modify the old region list. 4221 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4222 _collection_set->iterate(&_cl); 4223 } 4224 4225 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4226 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4227 4228 HeapRegion* r = g1h->region_at(region_idx); 4229 assert(!g1h->is_on_master_free_list(r), "sanity"); 4230 4231 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length); 4232 4233 if (!is_young) { 4234 g1h->hot_card_cache()->reset_card_counts(r); 4235 } 4236 4237 if (!evacuation_failed) { 4238 r->rem_set()->clear_locked(); 4239 } 4240 } 4241 4242 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4243 private: 4244 size_t _cur_idx; 4245 WorkItem* _work_items; 4246 public: 4247 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4248 4249 virtual bool do_heap_region(HeapRegion* r) { 4250 _work_items[_cur_idx++] = WorkItem(r); 4251 return false; 4252 } 4253 }; 4254 4255 void prepare_work() { 4256 G1PrepareFreeCollectionSetClosure cl(_work_items); 4257 _collection_set->iterate(&cl); 4258 } 4259 4260 void complete_work() { 4261 _cl.complete_work(); 4262 4263 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4264 policy->record_rs_length(_rs_length); 4265 policy->cset_regions_freed(); 4266 } 4267 public: 4268 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4269 AbstractGangTask("G1 Free Collection Set"), 4270 _collection_set(collection_set), 4271 _cl(evacuation_info, surviving_young_words), 4272 _surviving_young_words(surviving_young_words), 4273 _rs_length(0), 4274 _serial_work_claim(0), 4275 _parallel_work_claim(0), 4276 _num_work_items(collection_set->region_length()), 4277 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4278 prepare_work(); 4279 } 4280 4281 ~G1FreeCollectionSetTask() { 4282 complete_work(); 4283 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4284 } 4285 4286 // Chunk size for work distribution. The chosen value has been determined experimentally 4287 // to be a good tradeoff between overhead and achievable parallelism. 4288 static uint chunk_size() { return 32; } 4289 4290 virtual void work(uint worker_id) { 4291 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4292 4293 // Claim serial work. 4294 if (_serial_work_claim == 0) { 4295 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4296 if (value == 0) { 4297 double serial_time = os::elapsedTime(); 4298 do_serial_work(); 4299 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4300 } 4301 } 4302 4303 // Start parallel work. 4304 double young_time = 0.0; 4305 bool has_young_time = false; 4306 double non_young_time = 0.0; 4307 bool has_non_young_time = false; 4308 4309 while (true) { 4310 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4311 size_t cur = end - chunk_size(); 4312 4313 if (cur >= _num_work_items) { 4314 break; 4315 } 4316 4317 EventGCPhaseParallel event; 4318 double start_time = os::elapsedTime(); 4319 4320 end = MIN2(end, _num_work_items); 4321 4322 for (; cur < end; cur++) { 4323 bool is_young = _work_items[cur].is_young; 4324 4325 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4326 4327 double end_time = os::elapsedTime(); 4328 double time_taken = end_time - start_time; 4329 if (is_young) { 4330 young_time += time_taken; 4331 has_young_time = true; 4332 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4333 } else { 4334 non_young_time += time_taken; 4335 has_non_young_time = true; 4336 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4337 } 4338 start_time = end_time; 4339 } 4340 } 4341 4342 if (has_young_time) { 4343 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4344 } 4345 if (has_non_young_time) { 4346 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4347 } 4348 } 4349 }; 4350 4351 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4352 _eden.clear(); 4353 4354 double free_cset_start_time = os::elapsedTime(); 4355 4356 { 4357 uint const num_regions = _collection_set.region_length(); 4358 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4359 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4360 4361 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4362 4363 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4364 cl.name(), num_workers, num_regions); 4365 workers()->run_task(&cl, num_workers); 4366 } 4367 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4368 4369 collection_set->clear(); 4370 } 4371 4372 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4373 private: 4374 FreeRegionList* _free_region_list; 4375 HeapRegionSet* _proxy_set; 4376 uint _humongous_objects_reclaimed; 4377 uint _humongous_regions_reclaimed; 4378 size_t _freed_bytes; 4379 public: 4380 4381 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4382 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4383 } 4384 4385 virtual bool do_heap_region(HeapRegion* r) { 4386 if (!r->is_starts_humongous()) { 4387 return false; 4388 } 4389 4390 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4391 4392 oop obj = (oop)r->bottom(); 4393 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4394 4395 // The following checks whether the humongous object is live are sufficient. 4396 // The main additional check (in addition to having a reference from the roots 4397 // or the young gen) is whether the humongous object has a remembered set entry. 4398 // 4399 // A humongous object cannot be live if there is no remembered set for it 4400 // because: 4401 // - there can be no references from within humongous starts regions referencing 4402 // the object because we never allocate other objects into them. 4403 // (I.e. there are no intra-region references that may be missed by the 4404 // remembered set) 4405 // - as soon there is a remembered set entry to the humongous starts region 4406 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4407 // until the end of a concurrent mark. 4408 // 4409 // It is not required to check whether the object has been found dead by marking 4410 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4411 // all objects allocated during that time are considered live. 4412 // SATB marking is even more conservative than the remembered set. 4413 // So if at this point in the collection there is no remembered set entry, 4414 // nobody has a reference to it. 4415 // At the start of collection we flush all refinement logs, and remembered sets 4416 // are completely up-to-date wrt to references to the humongous object. 4417 // 4418 // Other implementation considerations: 4419 // - never consider object arrays at this time because they would pose 4420 // considerable effort for cleaning up the the remembered sets. This is 4421 // required because stale remembered sets might reference locations that 4422 // are currently allocated into. 4423 uint region_idx = r->hrm_index(); 4424 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4425 !r->rem_set()->is_empty()) { 4426 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", 4427 region_idx, 4428 (size_t)obj->size() * HeapWordSize, 4429 p2i(r->bottom()), 4430 r->rem_set()->occupied(), 4431 r->rem_set()->strong_code_roots_list_length(), 4432 next_bitmap->is_marked(r->bottom()), 4433 g1h->is_humongous_reclaim_candidate(region_idx), 4434 obj->is_typeArray() 4435 ); 4436 return false; 4437 } 4438 4439 guarantee(obj->is_typeArray(), 4440 "Only eagerly reclaiming type arrays is supported, but the object " 4441 PTR_FORMAT " is not.", p2i(r->bottom())); 4442 4443 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", 4444 region_idx, 4445 (size_t)obj->size() * HeapWordSize, 4446 p2i(r->bottom()), 4447 r->rem_set()->occupied(), 4448 r->rem_set()->strong_code_roots_list_length(), 4449 next_bitmap->is_marked(r->bottom()), 4450 g1h->is_humongous_reclaim_candidate(region_idx), 4451 obj->is_typeArray() 4452 ); 4453 4454 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4455 cm->humongous_object_eagerly_reclaimed(r); 4456 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4457 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4458 region_idx, 4459 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4460 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4461 _humongous_objects_reclaimed++; 4462 do { 4463 HeapRegion* next = g1h->next_region_in_humongous(r); 4464 _freed_bytes += r->used(); 4465 r->set_containing_set(NULL); 4466 _humongous_regions_reclaimed++; 4467 g1h->free_humongous_region(r, _free_region_list); 4468 r = next; 4469 } while (r != NULL); 4470 4471 return false; 4472 } 4473 4474 uint humongous_objects_reclaimed() { 4475 return _humongous_objects_reclaimed; 4476 } 4477 4478 uint humongous_regions_reclaimed() { 4479 return _humongous_regions_reclaimed; 4480 } 4481 4482 size_t bytes_freed() const { 4483 return _freed_bytes; 4484 } 4485 }; 4486 4487 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4488 assert_at_safepoint_on_vm_thread(); 4489 4490 if (!G1EagerReclaimHumongousObjects || 4491 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4492 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4493 return; 4494 } 4495 4496 double start_time = os::elapsedTime(); 4497 4498 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4499 4500 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4501 heap_region_iterate(&cl); 4502 4503 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4504 4505 G1HRPrinter* hrp = hr_printer(); 4506 if (hrp->is_active()) { 4507 FreeRegionListIterator iter(&local_cleanup_list); 4508 while (iter.more_available()) { 4509 HeapRegion* hr = iter.get_next(); 4510 hrp->cleanup(hr); 4511 } 4512 } 4513 4514 prepend_to_freelist(&local_cleanup_list); 4515 decrement_summary_bytes(cl.bytes_freed()); 4516 4517 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4518 cl.humongous_objects_reclaimed()); 4519 } 4520 4521 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4522 public: 4523 virtual bool do_heap_region(HeapRegion* r) { 4524 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4525 G1CollectedHeap::heap()->clear_region_attr(r); 4526 r->clear_young_index_in_cset(); 4527 return false; 4528 } 4529 }; 4530 4531 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4532 G1AbandonCollectionSetClosure cl; 4533 collection_set_iterate_all(&cl); 4534 4535 collection_set->clear(); 4536 collection_set->stop_incremental_building(); 4537 } 4538 4539 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4540 return _allocator->is_retained_old_region(hr); 4541 } 4542 4543 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4544 _eden.add(hr); 4545 _policy->set_region_eden(hr); 4546 } 4547 4548 #ifdef ASSERT 4549 4550 class NoYoungRegionsClosure: public HeapRegionClosure { 4551 private: 4552 bool _success; 4553 public: 4554 NoYoungRegionsClosure() : _success(true) { } 4555 bool do_heap_region(HeapRegion* r) { 4556 if (r->is_young()) { 4557 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4558 p2i(r->bottom()), p2i(r->end())); 4559 _success = false; 4560 } 4561 return false; 4562 } 4563 bool success() { return _success; } 4564 }; 4565 4566 bool G1CollectedHeap::check_young_list_empty() { 4567 bool ret = (young_regions_count() == 0); 4568 4569 NoYoungRegionsClosure closure; 4570 heap_region_iterate(&closure); 4571 ret = ret && closure.success(); 4572 4573 return ret; 4574 } 4575 4576 #endif // ASSERT 4577 4578 class TearDownRegionSetsClosure : public HeapRegionClosure { 4579 HeapRegionSet *_old_set; 4580 4581 public: 4582 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4583 4584 bool do_heap_region(HeapRegion* r) { 4585 if (r->is_old()) { 4586 _old_set->remove(r); 4587 } else if(r->is_young()) { 4588 r->uninstall_surv_rate_group(); 4589 } else { 4590 // We ignore free regions, we'll empty the free list afterwards. 4591 // We ignore humongous and archive regions, we're not tearing down these 4592 // sets. 4593 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4594 "it cannot be another type"); 4595 } 4596 return false; 4597 } 4598 4599 ~TearDownRegionSetsClosure() { 4600 assert(_old_set->is_empty(), "post-condition"); 4601 } 4602 }; 4603 4604 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4605 assert_at_safepoint_on_vm_thread(); 4606 4607 if (!free_list_only) { 4608 TearDownRegionSetsClosure cl(&_old_set); 4609 heap_region_iterate(&cl); 4610 4611 // Note that emptying the _young_list is postponed and instead done as 4612 // the first step when rebuilding the regions sets again. The reason for 4613 // this is that during a full GC string deduplication needs to know if 4614 // a collected region was young or old when the full GC was initiated. 4615 } 4616 _hrm->remove_all_free_regions(); 4617 } 4618 4619 void G1CollectedHeap::increase_used(size_t bytes) { 4620 _summary_bytes_used += bytes; 4621 } 4622 4623 void G1CollectedHeap::decrease_used(size_t bytes) { 4624 assert(_summary_bytes_used >= bytes, 4625 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4626 _summary_bytes_used, bytes); 4627 _summary_bytes_used -= bytes; 4628 } 4629 4630 void G1CollectedHeap::set_used(size_t bytes) { 4631 _summary_bytes_used = bytes; 4632 } 4633 4634 class RebuildRegionSetsClosure : public HeapRegionClosure { 4635 private: 4636 bool _free_list_only; 4637 4638 HeapRegionSet* _old_set; 4639 HeapRegionManager* _hrm; 4640 4641 size_t _total_used; 4642 4643 public: 4644 RebuildRegionSetsClosure(bool free_list_only, 4645 HeapRegionSet* old_set, 4646 HeapRegionManager* hrm) : 4647 _free_list_only(free_list_only), 4648 _old_set(old_set), _hrm(hrm), _total_used(0) { 4649 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4650 if (!free_list_only) { 4651 assert(_old_set->is_empty(), "pre-condition"); 4652 } 4653 } 4654 4655 bool do_heap_region(HeapRegion* r) { 4656 if (r->is_empty()) { 4657 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4658 // Add free regions to the free list 4659 r->set_free(); 4660 _hrm->insert_into_free_list(r); 4661 } else if (!_free_list_only) { 4662 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4663 4664 if (r->is_archive() || r->is_humongous()) { 4665 // We ignore archive and humongous regions. We left these sets unchanged. 4666 } else { 4667 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4668 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4669 r->move_to_old(); 4670 _old_set->add(r); 4671 } 4672 _total_used += r->used(); 4673 } 4674 4675 return false; 4676 } 4677 4678 size_t total_used() { 4679 return _total_used; 4680 } 4681 }; 4682 4683 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4684 assert_at_safepoint_on_vm_thread(); 4685 4686 if (!free_list_only) { 4687 _eden.clear(); 4688 _survivor.clear(); 4689 } 4690 4691 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4692 heap_region_iterate(&cl); 4693 4694 if (!free_list_only) { 4695 set_used(cl.total_used()); 4696 if (_archive_allocator != NULL) { 4697 _archive_allocator->clear_used(); 4698 } 4699 } 4700 assert_used_and_recalculate_used_equal(this); 4701 } 4702 4703 // Methods for the mutator alloc region 4704 4705 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4706 bool force, 4707 uint node_index) { 4708 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4709 bool should_allocate = policy()->should_allocate_mutator_region(); 4710 if (force || should_allocate) { 4711 HeapRegion* new_alloc_region = new_region(word_size, 4712 HeapRegionType::Eden, 4713 false /* do_expand */, 4714 node_index); 4715 if (new_alloc_region != NULL) { 4716 set_region_short_lived_locked(new_alloc_region); 4717 _hr_printer.alloc(new_alloc_region, !should_allocate); 4718 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4719 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4720 return new_alloc_region; 4721 } 4722 } 4723 return NULL; 4724 } 4725 4726 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4727 size_t allocated_bytes) { 4728 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4729 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4730 4731 collection_set()->add_eden_region(alloc_region); 4732 increase_used(allocated_bytes); 4733 _eden.add_used_bytes(allocated_bytes); 4734 _hr_printer.retire(alloc_region); 4735 4736 // We update the eden sizes here, when the region is retired, 4737 // instead of when it's allocated, since this is the point that its 4738 // used space has been recorded in _summary_bytes_used. 4739 g1mm()->update_eden_size(); 4740 } 4741 4742 // Methods for the GC alloc regions 4743 4744 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4745 if (dest.is_old()) { 4746 return true; 4747 } else { 4748 return survivor_regions_count() < policy()->max_survivor_regions(); 4749 } 4750 } 4751 4752 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4753 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4754 4755 if (!has_more_regions(dest)) { 4756 return NULL; 4757 } 4758 4759 HeapRegionType type; 4760 if (dest.is_young()) { 4761 type = HeapRegionType::Survivor; 4762 } else { 4763 type = HeapRegionType::Old; 4764 } 4765 4766 HeapRegion* new_alloc_region = new_region(word_size, 4767 type, 4768 true /* do_expand */, 4769 node_index); 4770 4771 if (new_alloc_region != NULL) { 4772 if (type.is_survivor()) { 4773 new_alloc_region->set_survivor(); 4774 _survivor.add(new_alloc_region); 4775 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4776 } else { 4777 new_alloc_region->set_old(); 4778 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4779 } 4780 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4781 register_region_with_region_attr(new_alloc_region); 4782 _hr_printer.alloc(new_alloc_region); 4783 return new_alloc_region; 4784 } 4785 return NULL; 4786 } 4787 4788 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4789 size_t allocated_bytes, 4790 G1HeapRegionAttr dest) { 4791 policy()->record_bytes_copied_during_gc(allocated_bytes); 4792 if (dest.is_old()) { 4793 old_set_add(alloc_region); 4794 } else { 4795 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4796 _survivor.add_used_bytes(allocated_bytes); 4797 } 4798 4799 bool const during_im = collector_state()->in_initial_mark_gc(); 4800 if (during_im && allocated_bytes > 0) { 4801 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4802 } 4803 _hr_printer.retire(alloc_region); 4804 } 4805 4806 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4807 bool expanded = false; 4808 uint index = _hrm->find_highest_free(&expanded); 4809 4810 if (index != G1_NO_HRM_INDEX) { 4811 if (expanded) { 4812 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4813 HeapRegion::GrainWords * HeapWordSize); 4814 } 4815 _hrm->allocate_free_regions_starting_at(index, 1); 4816 return region_at(index); 4817 } 4818 return NULL; 4819 } 4820 4821 // Optimized nmethod scanning 4822 4823 class RegisterNMethodOopClosure: public OopClosure { 4824 G1CollectedHeap* _g1h; 4825 nmethod* _nm; 4826 4827 template <class T> void do_oop_work(T* p) { 4828 T heap_oop = RawAccess<>::oop_load(p); 4829 if (!CompressedOops::is_null(heap_oop)) { 4830 oop obj = CompressedOops::decode_not_null(heap_oop); 4831 HeapRegion* hr = _g1h->heap_region_containing(obj); 4832 assert(!hr->is_continues_humongous(), 4833 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4834 " starting at " HR_FORMAT, 4835 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4836 4837 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4838 hr->add_strong_code_root_locked(_nm); 4839 } 4840 } 4841 4842 public: 4843 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4844 _g1h(g1h), _nm(nm) {} 4845 4846 void do_oop(oop* p) { do_oop_work(p); } 4847 void do_oop(narrowOop* p) { do_oop_work(p); } 4848 }; 4849 4850 class UnregisterNMethodOopClosure: public OopClosure { 4851 G1CollectedHeap* _g1h; 4852 nmethod* _nm; 4853 4854 template <class T> void do_oop_work(T* p) { 4855 T heap_oop = RawAccess<>::oop_load(p); 4856 if (!CompressedOops::is_null(heap_oop)) { 4857 oop obj = CompressedOops::decode_not_null(heap_oop); 4858 HeapRegion* hr = _g1h->heap_region_containing(obj); 4859 assert(!hr->is_continues_humongous(), 4860 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4861 " starting at " HR_FORMAT, 4862 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4863 4864 hr->remove_strong_code_root(_nm); 4865 } 4866 } 4867 4868 public: 4869 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4870 _g1h(g1h), _nm(nm) {} 4871 4872 void do_oop(oop* p) { do_oop_work(p); } 4873 void do_oop(narrowOop* p) { do_oop_work(p); } 4874 }; 4875 4876 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4877 guarantee(nm != NULL, "sanity"); 4878 RegisterNMethodOopClosure reg_cl(this, nm); 4879 nm->oops_do(®_cl); 4880 } 4881 4882 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4883 guarantee(nm != NULL, "sanity"); 4884 UnregisterNMethodOopClosure reg_cl(this, nm); 4885 nm->oops_do(®_cl, true); 4886 } 4887 4888 void G1CollectedHeap::purge_code_root_memory() { 4889 double purge_start = os::elapsedTime(); 4890 G1CodeRootSet::purge(); 4891 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4892 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4893 } 4894 4895 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4896 G1CollectedHeap* _g1h; 4897 4898 public: 4899 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4900 _g1h(g1h) {} 4901 4902 void do_code_blob(CodeBlob* cb) { 4903 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4904 if (nm == NULL) { 4905 return; 4906 } 4907 4908 _g1h->register_nmethod(nm); 4909 } 4910 }; 4911 4912 void G1CollectedHeap::rebuild_strong_code_roots() { 4913 RebuildStrongCodeRootClosure blob_cl(this); 4914 CodeCache::blobs_do(&blob_cl); 4915 } 4916 4917 void G1CollectedHeap::initialize_serviceability() { 4918 _g1mm->initialize_serviceability(); 4919 } 4920 4921 MemoryUsage G1CollectedHeap::memory_usage() { 4922 return _g1mm->memory_usage(); 4923 } 4924 4925 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4926 return _g1mm->memory_managers(); 4927 } 4928 4929 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4930 return _g1mm->memory_pools(); 4931 }