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 _bytes_used_during_gc(0), 1520 _archive_allocator(NULL), 1521 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1522 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1523 _expand_heap_after_alloc_failure(true), 1524 _g1mm(NULL), 1525 _humongous_reclaim_candidates(), 1526 _has_humongous_reclaim_candidates(false), 1527 _hr_printer(), 1528 _collector_state(), 1529 _old_marking_cycles_started(0), 1530 _old_marking_cycles_completed(0), 1531 _eden(), 1532 _survivor(), 1533 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1534 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1535 _policy(G1Policy::create_policy(_gc_timer_stw)), 1536 _heap_sizing_policy(NULL), 1537 _collection_set(this, _policy), 1538 _hot_card_cache(NULL), 1539 _rem_set(NULL), 1540 _cm(NULL), 1541 _cm_thread(NULL), 1542 _cr(NULL), 1543 _task_queues(NULL), 1544 _evacuation_failed(false), 1545 _evacuation_failed_info_array(NULL), 1546 _preserved_marks_set(true /* in_c_heap */), 1547 #ifndef PRODUCT 1548 _evacuation_failure_alot_for_current_gc(false), 1549 _evacuation_failure_alot_gc_number(0), 1550 _evacuation_failure_alot_count(0), 1551 #endif 1552 _ref_processor_stw(NULL), 1553 _is_alive_closure_stw(this), 1554 _is_subject_to_discovery_stw(this), 1555 _ref_processor_cm(NULL), 1556 _is_alive_closure_cm(this), 1557 _is_subject_to_discovery_cm(this), 1558 _region_attr() { 1559 1560 _verifier = new G1HeapVerifier(this); 1561 1562 _allocator = new G1Allocator(this); 1563 1564 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1565 1566 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1567 1568 // Override the default _filler_array_max_size so that no humongous filler 1569 // objects are created. 1570 _filler_array_max_size = _humongous_object_threshold_in_words; 1571 1572 uint n_queues = ParallelGCThreads; 1573 _task_queues = new RefToScanQueueSet(n_queues); 1574 1575 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1576 1577 for (uint i = 0; i < n_queues; i++) { 1578 RefToScanQueue* q = new RefToScanQueue(); 1579 q->initialize(); 1580 _task_queues->register_queue(i, q); 1581 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1582 } 1583 1584 // Initialize the G1EvacuationFailureALot counters and flags. 1585 NOT_PRODUCT(reset_evacuation_should_fail();) 1586 _gc_tracer_stw->initialize(); 1587 1588 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1589 } 1590 1591 static size_t actual_reserved_page_size(ReservedSpace rs) { 1592 size_t page_size = os::vm_page_size(); 1593 if (UseLargePages) { 1594 // There are two ways to manage large page memory. 1595 // 1. OS supports committing large page memory. 1596 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1597 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1598 // we reserved memory without large page. 1599 if (os::can_commit_large_page_memory() || rs.special()) { 1600 // An alignment at ReservedSpace comes from preferred page size or 1601 // heap alignment, and if the alignment came from heap alignment, it could be 1602 // larger than large pages size. So need to cap with the large page size. 1603 page_size = MIN2(rs.alignment(), os::large_page_size()); 1604 } 1605 } 1606 1607 return page_size; 1608 } 1609 1610 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1611 size_t size, 1612 size_t translation_factor) { 1613 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1614 // Allocate a new reserved space, preferring to use large pages. 1615 ReservedSpace rs(size, preferred_page_size); 1616 size_t page_size = actual_reserved_page_size(rs); 1617 G1RegionToSpaceMapper* result = 1618 G1RegionToSpaceMapper::create_mapper(rs, 1619 size, 1620 page_size, 1621 HeapRegion::GrainBytes, 1622 translation_factor, 1623 mtGC); 1624 1625 os::trace_page_sizes_for_requested_size(description, 1626 size, 1627 preferred_page_size, 1628 page_size, 1629 rs.base(), 1630 rs.size()); 1631 1632 return result; 1633 } 1634 1635 jint G1CollectedHeap::initialize_concurrent_refinement() { 1636 jint ecode = JNI_OK; 1637 _cr = G1ConcurrentRefine::create(&ecode); 1638 return ecode; 1639 } 1640 1641 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1642 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1643 if (_young_gen_sampling_thread->osthread() == NULL) { 1644 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1645 return JNI_ENOMEM; 1646 } 1647 return JNI_OK; 1648 } 1649 1650 jint G1CollectedHeap::initialize() { 1651 1652 // Necessary to satisfy locking discipline assertions. 1653 1654 MutexLocker x(Heap_lock); 1655 1656 // While there are no constraints in the GC code that HeapWordSize 1657 // be any particular value, there are multiple other areas in the 1658 // system which believe this to be true (e.g. oop->object_size in some 1659 // cases incorrectly returns the size in wordSize units rather than 1660 // HeapWordSize). 1661 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1662 1663 size_t init_byte_size = InitialHeapSize; 1664 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1665 1666 // Ensure that the sizes are properly aligned. 1667 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1668 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1669 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1670 1671 // Reserve the maximum. 1672 1673 // When compressed oops are enabled, the preferred heap base 1674 // is calculated by subtracting the requested size from the 1675 // 32Gb boundary and using the result as the base address for 1676 // heap reservation. If the requested size is not aligned to 1677 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1678 // into the ReservedHeapSpace constructor) then the actual 1679 // base of the reserved heap may end up differing from the 1680 // address that was requested (i.e. the preferred heap base). 1681 // If this happens then we could end up using a non-optimal 1682 // compressed oops mode. 1683 1684 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1685 HeapAlignment); 1686 1687 initialize_reserved_region(heap_rs); 1688 1689 // Create the barrier set for the entire reserved region. 1690 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1691 ct->initialize(); 1692 G1BarrierSet* bs = new G1BarrierSet(ct); 1693 bs->initialize(); 1694 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1695 BarrierSet::set_barrier_set(bs); 1696 _card_table = ct; 1697 1698 { 1699 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1700 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1701 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1702 } 1703 1704 // Create the hot card cache. 1705 _hot_card_cache = new G1HotCardCache(this); 1706 1707 // Carve out the G1 part of the heap. 1708 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1709 size_t page_size = actual_reserved_page_size(heap_rs); 1710 G1RegionToSpaceMapper* heap_storage = 1711 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1712 g1_rs.size(), 1713 page_size, 1714 HeapRegion::GrainBytes, 1715 1, 1716 mtJavaHeap); 1717 if(heap_storage == NULL) { 1718 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1719 return JNI_ERR; 1720 } 1721 1722 os::trace_page_sizes("Heap", 1723 MinHeapSize, 1724 reserved_byte_size, 1725 page_size, 1726 heap_rs.base(), 1727 heap_rs.size()); 1728 heap_storage->set_mapping_changed_listener(&_listener); 1729 1730 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1731 G1RegionToSpaceMapper* bot_storage = 1732 create_aux_memory_mapper("Block Offset Table", 1733 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1734 G1BlockOffsetTable::heap_map_factor()); 1735 1736 G1RegionToSpaceMapper* cardtable_storage = 1737 create_aux_memory_mapper("Card Table", 1738 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1739 G1CardTable::heap_map_factor()); 1740 1741 G1RegionToSpaceMapper* card_counts_storage = 1742 create_aux_memory_mapper("Card Counts Table", 1743 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1744 G1CardCounts::heap_map_factor()); 1745 1746 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1747 G1RegionToSpaceMapper* prev_bitmap_storage = 1748 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1749 G1RegionToSpaceMapper* next_bitmap_storage = 1750 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1751 1752 _hrm = HeapRegionManager::create_manager(this); 1753 1754 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1755 _card_table->initialize(cardtable_storage); 1756 1757 // Do later initialization work for concurrent refinement. 1758 _hot_card_cache->initialize(card_counts_storage); 1759 1760 // 6843694 - ensure that the maximum region index can fit 1761 // in the remembered set structures. 1762 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1763 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1764 1765 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1766 // start within the first card. 1767 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1768 // Also create a G1 rem set. 1769 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1770 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1771 1772 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1773 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1774 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1775 "too many cards per region"); 1776 1777 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1778 1779 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1780 1781 { 1782 HeapWord* start = _hrm->reserved().start(); 1783 HeapWord* end = _hrm->reserved().end(); 1784 size_t granularity = HeapRegion::GrainBytes; 1785 1786 _region_attr.initialize(start, end, granularity); 1787 _humongous_reclaim_candidates.initialize(start, end, granularity); 1788 } 1789 1790 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1791 true /* are_GC_task_threads */, 1792 false /* are_ConcurrentGC_threads */); 1793 if (_workers == NULL) { 1794 return JNI_ENOMEM; 1795 } 1796 _workers->initialize_workers(); 1797 1798 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1799 1800 // Create the G1ConcurrentMark data structure and thread. 1801 // (Must do this late, so that "max_regions" is defined.) 1802 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1803 if (_cm == NULL || !_cm->completed_initialization()) { 1804 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1805 return JNI_ENOMEM; 1806 } 1807 _cm_thread = _cm->cm_thread(); 1808 1809 // Now expand into the initial heap size. 1810 if (!expand(init_byte_size, _workers)) { 1811 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1812 return JNI_ENOMEM; 1813 } 1814 1815 // Perform any initialization actions delegated to the policy. 1816 policy()->init(this, &_collection_set); 1817 1818 jint ecode = initialize_concurrent_refinement(); 1819 if (ecode != JNI_OK) { 1820 return ecode; 1821 } 1822 1823 ecode = initialize_young_gen_sampling_thread(); 1824 if (ecode != JNI_OK) { 1825 return ecode; 1826 } 1827 1828 { 1829 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1830 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1831 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1832 } 1833 1834 // Here we allocate the dummy HeapRegion that is required by the 1835 // G1AllocRegion class. 1836 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1837 1838 // We'll re-use the same region whether the alloc region will 1839 // require BOT updates or not and, if it doesn't, then a non-young 1840 // region will complain that it cannot support allocations without 1841 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1842 dummy_region->set_eden(); 1843 // Make sure it's full. 1844 dummy_region->set_top(dummy_region->end()); 1845 G1AllocRegion::setup(this, dummy_region); 1846 1847 _allocator->init_mutator_alloc_regions(); 1848 1849 // Do create of the monitoring and management support so that 1850 // values in the heap have been properly initialized. 1851 _g1mm = new G1MonitoringSupport(this); 1852 1853 G1StringDedup::initialize(); 1854 1855 _preserved_marks_set.init(ParallelGCThreads); 1856 1857 _collection_set.initialize(max_regions()); 1858 1859 return JNI_OK; 1860 } 1861 1862 void G1CollectedHeap::stop() { 1863 // Stop all concurrent threads. We do this to make sure these threads 1864 // do not continue to execute and access resources (e.g. logging) 1865 // that are destroyed during shutdown. 1866 _cr->stop(); 1867 _young_gen_sampling_thread->stop(); 1868 _cm_thread->stop(); 1869 if (G1StringDedup::is_enabled()) { 1870 G1StringDedup::stop(); 1871 } 1872 } 1873 1874 void G1CollectedHeap::safepoint_synchronize_begin() { 1875 SuspendibleThreadSet::synchronize(); 1876 } 1877 1878 void G1CollectedHeap::safepoint_synchronize_end() { 1879 SuspendibleThreadSet::desynchronize(); 1880 } 1881 1882 void G1CollectedHeap::post_initialize() { 1883 CollectedHeap::post_initialize(); 1884 ref_processing_init(); 1885 } 1886 1887 void G1CollectedHeap::ref_processing_init() { 1888 // Reference processing in G1 currently works as follows: 1889 // 1890 // * There are two reference processor instances. One is 1891 // used to record and process discovered references 1892 // during concurrent marking; the other is used to 1893 // record and process references during STW pauses 1894 // (both full and incremental). 1895 // * Both ref processors need to 'span' the entire heap as 1896 // the regions in the collection set may be dotted around. 1897 // 1898 // * For the concurrent marking ref processor: 1899 // * Reference discovery is enabled at initial marking. 1900 // * Reference discovery is disabled and the discovered 1901 // references processed etc during remarking. 1902 // * Reference discovery is MT (see below). 1903 // * Reference discovery requires a barrier (see below). 1904 // * Reference processing may or may not be MT 1905 // (depending on the value of ParallelRefProcEnabled 1906 // and ParallelGCThreads). 1907 // * A full GC disables reference discovery by the CM 1908 // ref processor and abandons any entries on it's 1909 // discovered lists. 1910 // 1911 // * For the STW processor: 1912 // * Non MT discovery is enabled at the start of a full GC. 1913 // * Processing and enqueueing during a full GC is non-MT. 1914 // * During a full GC, references are processed after marking. 1915 // 1916 // * Discovery (may or may not be MT) is enabled at the start 1917 // of an incremental evacuation pause. 1918 // * References are processed near the end of a STW evacuation pause. 1919 // * For both types of GC: 1920 // * Discovery is atomic - i.e. not concurrent. 1921 // * Reference discovery will not need a barrier. 1922 1923 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1924 1925 // Concurrent Mark ref processor 1926 _ref_processor_cm = 1927 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1928 mt_processing, // mt processing 1929 ParallelGCThreads, // degree of mt processing 1930 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1931 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1932 false, // Reference discovery is not atomic 1933 &_is_alive_closure_cm, // is alive closure 1934 true); // allow changes to number of processing threads 1935 1936 // STW ref processor 1937 _ref_processor_stw = 1938 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1939 mt_processing, // mt processing 1940 ParallelGCThreads, // degree of mt processing 1941 (ParallelGCThreads > 1), // mt discovery 1942 ParallelGCThreads, // degree of mt discovery 1943 true, // Reference discovery is atomic 1944 &_is_alive_closure_stw, // is alive closure 1945 true); // allow changes to number of processing threads 1946 } 1947 1948 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1949 return &_soft_ref_policy; 1950 } 1951 1952 size_t G1CollectedHeap::capacity() const { 1953 return _hrm->length() * HeapRegion::GrainBytes; 1954 } 1955 1956 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1957 return _hrm->total_free_bytes(); 1958 } 1959 1960 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1961 _hot_card_cache->drain(cl, worker_id); 1962 } 1963 1964 // Computes the sum of the storage used by the various regions. 1965 size_t G1CollectedHeap::used() const { 1966 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1967 if (_archive_allocator != NULL) { 1968 result += _archive_allocator->used(); 1969 } 1970 return result; 1971 } 1972 1973 size_t G1CollectedHeap::used_unlocked() const { 1974 return _summary_bytes_used; 1975 } 1976 1977 class SumUsedClosure: public HeapRegionClosure { 1978 size_t _used; 1979 public: 1980 SumUsedClosure() : _used(0) {} 1981 bool do_heap_region(HeapRegion* r) { 1982 _used += r->used(); 1983 return false; 1984 } 1985 size_t result() { return _used; } 1986 }; 1987 1988 size_t G1CollectedHeap::recalculate_used() const { 1989 SumUsedClosure blk; 1990 heap_region_iterate(&blk); 1991 return blk.result(); 1992 } 1993 1994 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1995 switch (cause) { 1996 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1997 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1998 case GCCause::_wb_conc_mark: return true; 1999 default : return false; 2000 } 2001 } 2002 2003 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2004 switch (cause) { 2005 case GCCause::_g1_humongous_allocation: return true; 2006 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2007 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. 2285 return false; 2286 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2287 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2288 2289 // Schedule a standard evacuation pause. We're setting word_size 2290 // to 0 which means that we are not requesting a post-GC allocation. 2291 VM_G1CollectForAllocation op(0, /* word_size */ 2292 gc_count_before, 2293 cause, 2294 policy()->max_pause_time_ms()); 2295 VMThread::execute(&op); 2296 return op.gc_succeeded(); 2297 } else { 2298 // Schedule a Full GC. 2299 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2300 VMThread::execute(&op); 2301 return op.gc_succeeded(); 2302 } 2303 } 2304 2305 bool G1CollectedHeap::is_in(const void* p) const { 2306 if (_hrm->reserved().contains(p)) { 2307 // Given that we know that p is in the reserved space, 2308 // heap_region_containing() should successfully 2309 // return the containing region. 2310 HeapRegion* hr = heap_region_containing(p); 2311 return hr->is_in(p); 2312 } else { 2313 return false; 2314 } 2315 } 2316 2317 #ifdef ASSERT 2318 bool G1CollectedHeap::is_in_exact(const void* p) const { 2319 bool contains = reserved_region().contains(p); 2320 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2321 if (contains && available) { 2322 return true; 2323 } else { 2324 return false; 2325 } 2326 } 2327 #endif 2328 2329 // Iteration functions. 2330 2331 // Iterates an ObjectClosure over all objects within a HeapRegion. 2332 2333 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2334 ObjectClosure* _cl; 2335 public: 2336 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2337 bool do_heap_region(HeapRegion* r) { 2338 if (!r->is_continues_humongous()) { 2339 r->object_iterate(_cl); 2340 } 2341 return false; 2342 } 2343 }; 2344 2345 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2346 IterateObjectClosureRegionClosure blk(cl); 2347 heap_region_iterate(&blk); 2348 } 2349 2350 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2351 _hrm->iterate(cl); 2352 } 2353 2354 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2355 HeapRegionClaimer *hrclaimer, 2356 uint worker_id) const { 2357 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2358 } 2359 2360 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2361 HeapRegionClaimer *hrclaimer) const { 2362 _hrm->par_iterate(cl, hrclaimer, 0); 2363 } 2364 2365 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2366 _collection_set.iterate(cl); 2367 } 2368 2369 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2370 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2371 } 2372 2373 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2374 HeapRegion* hr = heap_region_containing(addr); 2375 return hr->block_start(addr); 2376 } 2377 2378 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2379 HeapRegion* hr = heap_region_containing(addr); 2380 return hr->block_is_obj(addr); 2381 } 2382 2383 bool G1CollectedHeap::supports_tlab_allocation() const { 2384 return true; 2385 } 2386 2387 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2388 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2389 } 2390 2391 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2392 return _eden.length() * HeapRegion::GrainBytes; 2393 } 2394 2395 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2396 // must be equal to the humongous object limit. 2397 size_t G1CollectedHeap::max_tlab_size() const { 2398 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2399 } 2400 2401 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2402 return _allocator->unsafe_max_tlab_alloc(); 2403 } 2404 2405 size_t G1CollectedHeap::max_capacity() const { 2406 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2407 } 2408 2409 size_t G1CollectedHeap::max_reserved_capacity() const { 2410 return _hrm->max_length() * HeapRegion::GrainBytes; 2411 } 2412 2413 jlong G1CollectedHeap::millis_since_last_gc() { 2414 // See the notes in GenCollectedHeap::millis_since_last_gc() 2415 // for more information about the implementation. 2416 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2417 _policy->collection_pause_end_millis(); 2418 if (ret_val < 0) { 2419 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2420 ". returning zero instead.", ret_val); 2421 return 0; 2422 } 2423 return ret_val; 2424 } 2425 2426 void G1CollectedHeap::deduplicate_string(oop str) { 2427 assert(java_lang_String::is_instance(str), "invariant"); 2428 2429 if (G1StringDedup::is_enabled()) { 2430 G1StringDedup::deduplicate(str); 2431 } 2432 } 2433 2434 void G1CollectedHeap::prepare_for_verify() { 2435 _verifier->prepare_for_verify(); 2436 } 2437 2438 void G1CollectedHeap::verify(VerifyOption vo) { 2439 _verifier->verify(vo); 2440 } 2441 2442 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2443 return true; 2444 } 2445 2446 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2447 return _cm_thread->request_concurrent_phase(phase); 2448 } 2449 2450 bool G1CollectedHeap::is_heterogeneous_heap() const { 2451 return G1Arguments::is_heterogeneous_heap(); 2452 } 2453 2454 class PrintRegionClosure: public HeapRegionClosure { 2455 outputStream* _st; 2456 public: 2457 PrintRegionClosure(outputStream* st) : _st(st) {} 2458 bool do_heap_region(HeapRegion* r) { 2459 r->print_on(_st); 2460 return false; 2461 } 2462 }; 2463 2464 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2465 const HeapRegion* hr, 2466 const VerifyOption vo) const { 2467 switch (vo) { 2468 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2469 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2470 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2471 default: ShouldNotReachHere(); 2472 } 2473 return false; // keep some compilers happy 2474 } 2475 2476 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2477 const VerifyOption vo) const { 2478 switch (vo) { 2479 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2480 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2481 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2482 default: ShouldNotReachHere(); 2483 } 2484 return false; // keep some compilers happy 2485 } 2486 2487 void G1CollectedHeap::print_heap_regions() const { 2488 LogTarget(Trace, gc, heap, region) lt; 2489 if (lt.is_enabled()) { 2490 LogStream ls(lt); 2491 print_regions_on(&ls); 2492 } 2493 } 2494 2495 void G1CollectedHeap::print_on(outputStream* st) const { 2496 st->print(" %-20s", "garbage-first heap"); 2497 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2498 capacity()/K, used_unlocked()/K); 2499 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2500 p2i(_hrm->reserved().start()), 2501 p2i(_hrm->reserved().end())); 2502 st->cr(); 2503 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2504 uint young_regions = young_regions_count(); 2505 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2506 (size_t) young_regions * HeapRegion::GrainBytes / K); 2507 uint survivor_regions = survivor_regions_count(); 2508 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2509 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2510 st->cr(); 2511 if (_numa->is_enabled()) { 2512 uint num_nodes = _numa->num_active_nodes(); 2513 st->print(" remaining free region(s) on each NUMA node: "); 2514 const int* node_ids = _numa->node_ids(); 2515 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2516 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index)); 2517 } 2518 st->cr(); 2519 } 2520 MetaspaceUtils::print_on(st); 2521 } 2522 2523 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2524 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2525 "HS=humongous(starts), HC=humongous(continues), " 2526 "CS=collection set, F=free, " 2527 "OA=open archive, CA=closed archive, " 2528 "TAMS=top-at-mark-start (previous, next)"); 2529 PrintRegionClosure blk(st); 2530 heap_region_iterate(&blk); 2531 } 2532 2533 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2534 print_on(st); 2535 2536 // Print the per-region information. 2537 print_regions_on(st); 2538 } 2539 2540 void G1CollectedHeap::print_on_error(outputStream* st) const { 2541 this->CollectedHeap::print_on_error(st); 2542 2543 if (_cm != NULL) { 2544 st->cr(); 2545 _cm->print_on_error(st); 2546 } 2547 } 2548 2549 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2550 workers()->print_worker_threads_on(st); 2551 _cm_thread->print_on(st); 2552 st->cr(); 2553 _cm->print_worker_threads_on(st); 2554 _cr->print_threads_on(st); 2555 _young_gen_sampling_thread->print_on(st); 2556 if (G1StringDedup::is_enabled()) { 2557 G1StringDedup::print_worker_threads_on(st); 2558 } 2559 } 2560 2561 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2562 workers()->threads_do(tc); 2563 tc->do_thread(_cm_thread); 2564 _cm->threads_do(tc); 2565 _cr->threads_do(tc); 2566 tc->do_thread(_young_gen_sampling_thread); 2567 if (G1StringDedup::is_enabled()) { 2568 G1StringDedup::threads_do(tc); 2569 } 2570 } 2571 2572 void G1CollectedHeap::print_tracing_info() const { 2573 rem_set()->print_summary_info(); 2574 concurrent_mark()->print_summary_info(); 2575 } 2576 2577 #ifndef PRODUCT 2578 // Helpful for debugging RSet issues. 2579 2580 class PrintRSetsClosure : public HeapRegionClosure { 2581 private: 2582 const char* _msg; 2583 size_t _occupied_sum; 2584 2585 public: 2586 bool do_heap_region(HeapRegion* r) { 2587 HeapRegionRemSet* hrrs = r->rem_set(); 2588 size_t occupied = hrrs->occupied(); 2589 _occupied_sum += occupied; 2590 2591 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2592 if (occupied == 0) { 2593 tty->print_cr(" RSet is empty"); 2594 } else { 2595 hrrs->print(); 2596 } 2597 tty->print_cr("----------"); 2598 return false; 2599 } 2600 2601 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2602 tty->cr(); 2603 tty->print_cr("========================================"); 2604 tty->print_cr("%s", msg); 2605 tty->cr(); 2606 } 2607 2608 ~PrintRSetsClosure() { 2609 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2610 tty->print_cr("========================================"); 2611 tty->cr(); 2612 } 2613 }; 2614 2615 void G1CollectedHeap::print_cset_rsets() { 2616 PrintRSetsClosure cl("Printing CSet RSets"); 2617 collection_set_iterate_all(&cl); 2618 } 2619 2620 void G1CollectedHeap::print_all_rsets() { 2621 PrintRSetsClosure cl("Printing All RSets");; 2622 heap_region_iterate(&cl); 2623 } 2624 #endif // PRODUCT 2625 2626 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2627 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2628 } 2629 2630 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2631 2632 size_t eden_used_bytes = _eden.used_bytes(); 2633 size_t survivor_used_bytes = _survivor.used_bytes(); 2634 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2635 2636 size_t eden_capacity_bytes = 2637 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2638 2639 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2640 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2641 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2642 } 2643 2644 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2645 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2646 stats->unused(), stats->used(), stats->region_end_waste(), 2647 stats->regions_filled(), stats->direct_allocated(), 2648 stats->failure_used(), stats->failure_waste()); 2649 } 2650 2651 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2652 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2653 gc_tracer->report_gc_heap_summary(when, heap_summary); 2654 2655 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2656 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2657 } 2658 2659 G1CollectedHeap* G1CollectedHeap::heap() { 2660 CollectedHeap* heap = Universe::heap(); 2661 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2662 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2663 return (G1CollectedHeap*)heap; 2664 } 2665 2666 void G1CollectedHeap::gc_prologue(bool full) { 2667 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2668 2669 // This summary needs to be printed before incrementing total collections. 2670 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2671 2672 // Update common counters. 2673 increment_total_collections(full /* full gc */); 2674 if (full || collector_state()->in_initial_mark_gc()) { 2675 increment_old_marking_cycles_started(); 2676 } 2677 2678 // Fill TLAB's and such 2679 double start = os::elapsedTime(); 2680 ensure_parsability(true); 2681 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2682 } 2683 2684 void G1CollectedHeap::gc_epilogue(bool full) { 2685 // Update common counters. 2686 if (full) { 2687 // Update the number of full collections that have been completed. 2688 increment_old_marking_cycles_completed(false /* concurrent */); 2689 } 2690 2691 // We are at the end of the GC. Total collections has already been increased. 2692 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2693 2694 // FIXME: what is this about? 2695 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2696 // is set. 2697 #if COMPILER2_OR_JVMCI 2698 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2699 #endif 2700 2701 double start = os::elapsedTime(); 2702 resize_all_tlabs(); 2703 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2704 2705 MemoryService::track_memory_usage(); 2706 // We have just completed a GC. Update the soft reference 2707 // policy with the new heap occupancy 2708 Universe::update_heap_info_at_gc(); 2709 2710 // Print NUMA statistics. 2711 _numa->print_statistics(); 2712 } 2713 2714 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2715 LogTarget(Trace, gc, heap, verify) lt; 2716 2717 if (lt.is_enabled()) { 2718 LogStream ls(lt); 2719 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2720 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2721 heap_region_iterate(&cl); 2722 } 2723 } 2724 2725 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2726 uint gc_count_before, 2727 bool* succeeded, 2728 GCCause::Cause gc_cause) { 2729 assert_heap_not_locked_and_not_at_safepoint(); 2730 VM_G1CollectForAllocation op(word_size, 2731 gc_count_before, 2732 gc_cause, 2733 policy()->max_pause_time_ms()); 2734 VMThread::execute(&op); 2735 2736 HeapWord* result = op.result(); 2737 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2738 assert(result == NULL || ret_succeeded, 2739 "the result should be NULL if the VM did not succeed"); 2740 *succeeded = ret_succeeded; 2741 2742 assert_heap_not_locked(); 2743 return result; 2744 } 2745 2746 void G1CollectedHeap::do_concurrent_mark() { 2747 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2748 if (!_cm_thread->in_progress()) { 2749 _cm_thread->set_started(); 2750 CGC_lock->notify(); 2751 } 2752 } 2753 2754 size_t G1CollectedHeap::pending_card_num() { 2755 struct CountCardsClosure : public ThreadClosure { 2756 size_t _cards; 2757 CountCardsClosure() : _cards(0) {} 2758 virtual void do_thread(Thread* t) { 2759 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2760 } 2761 } count_from_threads; 2762 Threads::threads_do(&count_from_threads); 2763 2764 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2765 dcqs.verify_num_cards(); 2766 2767 return dcqs.num_cards() + count_from_threads._cards; 2768 } 2769 2770 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2771 // We don't nominate objects with many remembered set entries, on 2772 // the assumption that such objects are likely still live. 2773 HeapRegionRemSet* rem_set = r->rem_set(); 2774 2775 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2776 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2777 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2778 } 2779 2780 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2781 private: 2782 size_t _total_humongous; 2783 size_t _candidate_humongous; 2784 2785 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2786 assert(region->is_starts_humongous(), "Must start a humongous object"); 2787 2788 oop obj = oop(region->bottom()); 2789 2790 // Dead objects cannot be eager reclaim candidates. Due to class 2791 // unloading it is unsafe to query their classes so we return early. 2792 if (g1h->is_obj_dead(obj, region)) { 2793 return false; 2794 } 2795 2796 // If we do not have a complete remembered set for the region, then we can 2797 // not be sure that we have all references to it. 2798 if (!region->rem_set()->is_complete()) { 2799 return false; 2800 } 2801 // Candidate selection must satisfy the following constraints 2802 // while concurrent marking is in progress: 2803 // 2804 // * In order to maintain SATB invariants, an object must not be 2805 // reclaimed if it was allocated before the start of marking and 2806 // has not had its references scanned. Such an object must have 2807 // its references (including type metadata) scanned to ensure no 2808 // live objects are missed by the marking process. Objects 2809 // allocated after the start of concurrent marking don't need to 2810 // be scanned. 2811 // 2812 // * An object must not be reclaimed if it is on the concurrent 2813 // mark stack. Objects allocated after the start of concurrent 2814 // marking are never pushed on the mark stack. 2815 // 2816 // Nominating only objects allocated after the start of concurrent 2817 // marking is sufficient to meet both constraints. This may miss 2818 // some objects that satisfy the constraints, but the marking data 2819 // structures don't support efficiently performing the needed 2820 // additional tests or scrubbing of the mark stack. 2821 // 2822 // However, we presently only nominate is_typeArray() objects. 2823 // A humongous object containing references induces remembered 2824 // set entries on other regions. In order to reclaim such an 2825 // object, those remembered sets would need to be cleaned up. 2826 // 2827 // We also treat is_typeArray() objects specially, allowing them 2828 // to be reclaimed even if allocated before the start of 2829 // concurrent mark. For this we rely on mark stack insertion to 2830 // exclude is_typeArray() objects, preventing reclaiming an object 2831 // that is in the mark stack. We also rely on the metadata for 2832 // such objects to be built-in and so ensured to be kept live. 2833 // Frequent allocation and drop of large binary blobs is an 2834 // important use case for eager reclaim, and this special handling 2835 // may reduce needed headroom. 2836 2837 return obj->is_typeArray() && 2838 g1h->is_potential_eager_reclaim_candidate(region); 2839 } 2840 2841 public: 2842 RegisterRegionsWithRegionAttrTableClosure() 2843 : _total_humongous(0), 2844 _candidate_humongous(0) { 2845 } 2846 2847 virtual bool do_heap_region(HeapRegion* r) { 2848 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2849 2850 if (!r->is_starts_humongous()) { 2851 g1h->register_region_with_region_attr(r); 2852 return false; 2853 } 2854 2855 bool is_candidate = humongous_region_is_candidate(g1h, r); 2856 uint rindex = r->hrm_index(); 2857 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2858 if (is_candidate) { 2859 g1h->register_humongous_region_with_region_attr(rindex); 2860 _candidate_humongous++; 2861 // We will later handle the remembered sets of these regions. 2862 } else { 2863 g1h->register_region_with_region_attr(r); 2864 } 2865 _total_humongous++; 2866 2867 return false; 2868 } 2869 2870 size_t total_humongous() const { return _total_humongous; } 2871 size_t candidate_humongous() const { return _candidate_humongous; } 2872 }; 2873 2874 void G1CollectedHeap::register_regions_with_region_attr() { 2875 Ticks start = Ticks::now(); 2876 2877 RegisterRegionsWithRegionAttrTableClosure cl; 2878 heap_region_iterate(&cl); 2879 2880 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2881 cl.total_humongous(), 2882 cl.candidate_humongous()); 2883 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2884 } 2885 2886 #ifndef PRODUCT 2887 void G1CollectedHeap::verify_region_attr_remset_update() { 2888 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2889 public: 2890 virtual bool do_heap_region(HeapRegion* r) { 2891 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2892 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2893 assert(r->rem_set()->is_tracked() == needs_remset_update, 2894 "Region %u remset tracking status (%s) different to region attribute (%s)", 2895 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2896 return false; 2897 } 2898 } cl; 2899 heap_region_iterate(&cl); 2900 } 2901 #endif 2902 2903 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2904 public: 2905 bool do_heap_region(HeapRegion* hr) { 2906 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2907 hr->verify_rem_set(); 2908 } 2909 return false; 2910 } 2911 }; 2912 2913 uint G1CollectedHeap::num_task_queues() const { 2914 return _task_queues->size(); 2915 } 2916 2917 #if TASKQUEUE_STATS 2918 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2919 st->print_raw_cr("GC Task Stats"); 2920 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2921 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2922 } 2923 2924 void G1CollectedHeap::print_taskqueue_stats() const { 2925 if (!log_is_enabled(Trace, gc, task, stats)) { 2926 return; 2927 } 2928 Log(gc, task, stats) log; 2929 ResourceMark rm; 2930 LogStream ls(log.trace()); 2931 outputStream* st = &ls; 2932 2933 print_taskqueue_stats_hdr(st); 2934 2935 TaskQueueStats totals; 2936 const uint n = num_task_queues(); 2937 for (uint i = 0; i < n; ++i) { 2938 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2939 totals += task_queue(i)->stats; 2940 } 2941 st->print_raw("tot "); totals.print(st); st->cr(); 2942 2943 DEBUG_ONLY(totals.verify()); 2944 } 2945 2946 void G1CollectedHeap::reset_taskqueue_stats() { 2947 const uint n = num_task_queues(); 2948 for (uint i = 0; i < n; ++i) { 2949 task_queue(i)->stats.reset(); 2950 } 2951 } 2952 #endif // TASKQUEUE_STATS 2953 2954 void G1CollectedHeap::wait_for_root_region_scanning() { 2955 double scan_wait_start = os::elapsedTime(); 2956 // We have to wait until the CM threads finish scanning the 2957 // root regions as it's the only way to ensure that all the 2958 // objects on them have been correctly scanned before we start 2959 // moving them during the GC. 2960 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2961 double wait_time_ms = 0.0; 2962 if (waited) { 2963 double scan_wait_end = os::elapsedTime(); 2964 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2965 } 2966 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2967 } 2968 2969 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2970 private: 2971 G1HRPrinter* _hr_printer; 2972 public: 2973 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2974 2975 virtual bool do_heap_region(HeapRegion* r) { 2976 _hr_printer->cset(r); 2977 return false; 2978 } 2979 }; 2980 2981 void G1CollectedHeap::start_new_collection_set() { 2982 double start = os::elapsedTime(); 2983 2984 collection_set()->start_incremental_building(); 2985 2986 clear_region_attr(); 2987 2988 guarantee(_eden.length() == 0, "eden should have been cleared"); 2989 policy()->transfer_survivors_to_cset(survivor()); 2990 2991 // We redo the verification but now wrt to the new CSet which 2992 // has just got initialized after the previous CSet was freed. 2993 _cm->verify_no_collection_set_oops(); 2994 2995 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2996 } 2997 2998 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2999 3000 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 3001 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 3002 collection_set()->optional_region_length()); 3003 3004 _cm->verify_no_collection_set_oops(); 3005 3006 if (_hr_printer.is_active()) { 3007 G1PrintCollectionSetClosure cl(&_hr_printer); 3008 _collection_set.iterate(&cl); 3009 _collection_set.iterate_optional(&cl); 3010 } 3011 } 3012 3013 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 3014 if (collector_state()->in_initial_mark_gc()) { 3015 return G1HeapVerifier::G1VerifyConcurrentStart; 3016 } else if (collector_state()->in_young_only_phase()) { 3017 return G1HeapVerifier::G1VerifyYoungNormal; 3018 } else { 3019 return G1HeapVerifier::G1VerifyMixed; 3020 } 3021 } 3022 3023 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 3024 if (VerifyRememberedSets) { 3025 log_info(gc, verify)("[Verifying RemSets before GC]"); 3026 VerifyRegionRemSetClosure v_cl; 3027 heap_region_iterate(&v_cl); 3028 } 3029 _verifier->verify_before_gc(type); 3030 _verifier->check_bitmaps("GC Start"); 3031 verify_numa_regions("GC Start"); 3032 } 3033 3034 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 3035 if (VerifyRememberedSets) { 3036 log_info(gc, verify)("[Verifying RemSets after GC]"); 3037 VerifyRegionRemSetClosure v_cl; 3038 heap_region_iterate(&v_cl); 3039 } 3040 _verifier->verify_after_gc(type); 3041 _verifier->check_bitmaps("GC End"); 3042 verify_numa_regions("GC End"); 3043 } 3044 3045 void G1CollectedHeap::expand_heap_after_young_collection(){ 3046 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3047 if (expand_bytes > 0) { 3048 // No need for an ergo logging here, 3049 // expansion_amount() does this when it returns a value > 0. 3050 double expand_ms; 3051 if (!expand(expand_bytes, _workers, &expand_ms)) { 3052 // We failed to expand the heap. Cannot do anything about it. 3053 } 3054 phase_times()->record_expand_heap_time(expand_ms); 3055 } 3056 } 3057 3058 const char* G1CollectedHeap::young_gc_name() const { 3059 if (collector_state()->in_initial_mark_gc()) { 3060 return "Pause Young (Concurrent Start)"; 3061 } else if (collector_state()->in_young_only_phase()) { 3062 if (collector_state()->in_young_gc_before_mixed()) { 3063 return "Pause Young (Prepare Mixed)"; 3064 } else { 3065 return "Pause Young (Normal)"; 3066 } 3067 } else { 3068 return "Pause Young (Mixed)"; 3069 } 3070 } 3071 3072 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 3073 assert_at_safepoint_on_vm_thread(); 3074 guarantee(!is_gc_active(), "collection is not reentrant"); 3075 3076 if (GCLocker::check_active_before_gc()) { 3077 return false; 3078 } 3079 3080 GCIdMark gc_id_mark; 3081 3082 SvcGCMarker sgcm(SvcGCMarker::MINOR); 3083 ResourceMark rm; 3084 3085 policy()->note_gc_start(); 3086 3087 _gc_timer_stw->register_gc_start(); 3088 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3089 3090 wait_for_root_region_scanning(); 3091 3092 print_heap_before_gc(); 3093 print_heap_regions(); 3094 trace_heap_before_gc(_gc_tracer_stw); 3095 3096 _verifier->verify_region_sets_optional(); 3097 _verifier->verify_dirty_young_regions(); 3098 3099 // We should not be doing initial mark unless the conc mark thread is running 3100 if (!_cm_thread->should_terminate()) { 3101 // This call will decide whether this pause is an initial-mark 3102 // pause. If it is, in_initial_mark_gc() will return true 3103 // for the duration of this pause. 3104 policy()->decide_on_conc_mark_initiation(); 3105 } 3106 3107 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3108 assert(!collector_state()->in_initial_mark_gc() || 3109 collector_state()->in_young_only_phase(), "sanity"); 3110 // We also do not allow mixed GCs during marking. 3111 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 3112 3113 // Record whether this pause is an initial mark. When the current 3114 // thread has completed its logging output and it's safe to signal 3115 // the CM thread, the flag's value in the policy has been reset. 3116 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 3117 if (should_start_conc_mark) { 3118 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3119 } 3120 3121 // Inner scope for scope based logging, timers, and stats collection 3122 { 3123 G1EvacuationInfo evacuation_info; 3124 3125 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3126 3127 GCTraceCPUTime tcpu; 3128 3129 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3130 3131 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3132 workers()->active_workers(), 3133 Threads::number_of_non_daemon_threads()); 3134 active_workers = workers()->update_active_workers(active_workers); 3135 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3136 3137 G1MonitoringScope ms(g1mm(), 3138 false /* full_gc */, 3139 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3140 3141 G1HeapTransition heap_transition(this); 3142 3143 { 3144 IsGCActiveMark x; 3145 3146 gc_prologue(false); 3147 3148 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3149 verify_before_young_collection(verify_type); 3150 3151 { 3152 // The elapsed time induced by the start time below deliberately elides 3153 // the possible verification above. 3154 double sample_start_time_sec = os::elapsedTime(); 3155 3156 // Please see comment in g1CollectedHeap.hpp and 3157 // G1CollectedHeap::ref_processing_init() to see how 3158 // reference processing currently works in G1. 3159 _ref_processor_stw->enable_discovery(); 3160 3161 // We want to temporarily turn off discovery by the 3162 // CM ref processor, if necessary, and turn it back on 3163 // on again later if we do. Using a scoped 3164 // NoRefDiscovery object will do this. 3165 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3166 3167 policy()->record_collection_pause_start(sample_start_time_sec); 3168 3169 // Forget the current allocation region (we might even choose it to be part 3170 // of the collection set!). 3171 _allocator->release_mutator_alloc_regions(); 3172 3173 calculate_collection_set(evacuation_info, target_pause_time_ms); 3174 3175 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3176 G1ParScanThreadStateSet per_thread_states(this, 3177 &rdcqs, 3178 workers()->active_workers(), 3179 collection_set()->young_region_length(), 3180 collection_set()->optional_region_length()); 3181 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3182 3183 // Actually do the work... 3184 evacuate_initial_collection_set(&per_thread_states); 3185 3186 if (_collection_set.optional_region_length() != 0) { 3187 evacuate_optional_collection_set(&per_thread_states); 3188 } 3189 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3190 3191 start_new_collection_set(); 3192 3193 _survivor_evac_stats.adjust_desired_plab_sz(); 3194 _old_evac_stats.adjust_desired_plab_sz(); 3195 3196 if (should_start_conc_mark) { 3197 // We have to do this before we notify the CM threads that 3198 // they can start working to make sure that all the 3199 // appropriate initialization is done on the CM object. 3200 concurrent_mark()->post_initial_mark(); 3201 // Note that we don't actually trigger the CM thread at 3202 // this point. We do that later when we're sure that 3203 // the current thread has completed its logging output. 3204 } 3205 3206 allocate_dummy_regions(); 3207 3208 _allocator->init_mutator_alloc_regions(); 3209 3210 expand_heap_after_young_collection(); 3211 3212 double sample_end_time_sec = os::elapsedTime(); 3213 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3214 policy()->record_collection_pause_end(pause_time_ms); 3215 } 3216 3217 verify_after_young_collection(verify_type); 3218 3219 #ifdef TRACESPINNING 3220 ParallelTaskTerminator::print_termination_counts(); 3221 #endif 3222 3223 gc_epilogue(false); 3224 } 3225 3226 // Print the remainder of the GC log output. 3227 if (evacuation_failed()) { 3228 log_info(gc)("To-space exhausted"); 3229 } 3230 3231 policy()->print_phases(); 3232 heap_transition.print(); 3233 3234 _hrm->verify_optional(); 3235 _verifier->verify_region_sets_optional(); 3236 3237 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3238 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3239 3240 print_heap_after_gc(); 3241 print_heap_regions(); 3242 trace_heap_after_gc(_gc_tracer_stw); 3243 3244 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3245 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3246 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3247 // before any GC notifications are raised. 3248 g1mm()->update_sizes(); 3249 3250 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3251 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3252 _gc_timer_stw->register_gc_end(); 3253 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3254 } 3255 // It should now be safe to tell the concurrent mark thread to start 3256 // without its logging output interfering with the logging output 3257 // that came from the pause. 3258 3259 if (should_start_conc_mark) { 3260 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3261 // thread(s) could be running concurrently with us. Make sure that anything 3262 // after this point does not assume that we are the only GC thread running. 3263 // Note: of course, the actual marking work will not start until the safepoint 3264 // itself is released in SuspendibleThreadSet::desynchronize(). 3265 do_concurrent_mark(); 3266 } 3267 3268 return true; 3269 } 3270 3271 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3272 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3273 workers()->run_task(&rsfp_task); 3274 } 3275 3276 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3277 double remove_self_forwards_start = os::elapsedTime(); 3278 3279 remove_self_forwarding_pointers(rdcqs); 3280 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3281 _preserved_marks_set.restore(&task_executor); 3282 3283 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3284 } 3285 3286 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3287 if (!_evacuation_failed) { 3288 _evacuation_failed = true; 3289 } 3290 3291 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3292 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3293 } 3294 3295 bool G1ParEvacuateFollowersClosure::offer_termination() { 3296 EventGCPhaseParallel event; 3297 G1ParScanThreadState* const pss = par_scan_state(); 3298 start_term_time(); 3299 const bool res = terminator()->offer_termination(); 3300 end_term_time(); 3301 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3302 return res; 3303 } 3304 3305 void G1ParEvacuateFollowersClosure::do_void() { 3306 EventGCPhaseParallel event; 3307 G1ParScanThreadState* const pss = par_scan_state(); 3308 pss->trim_queue(); 3309 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3310 do { 3311 EventGCPhaseParallel event; 3312 pss->steal_and_trim_queue(queues()); 3313 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3314 } while (!offer_termination()); 3315 } 3316 3317 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3318 bool class_unloading_occurred) { 3319 uint num_workers = workers()->active_workers(); 3320 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3321 workers()->run_task(&unlink_task); 3322 } 3323 3324 // Clean string dedup data structures. 3325 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3326 // record the durations of the phases. Hence the almost-copy. 3327 class G1StringDedupCleaningTask : public AbstractGangTask { 3328 BoolObjectClosure* _is_alive; 3329 OopClosure* _keep_alive; 3330 G1GCPhaseTimes* _phase_times; 3331 3332 public: 3333 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3334 OopClosure* keep_alive, 3335 G1GCPhaseTimes* phase_times) : 3336 AbstractGangTask("Partial Cleaning Task"), 3337 _is_alive(is_alive), 3338 _keep_alive(keep_alive), 3339 _phase_times(phase_times) 3340 { 3341 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3342 StringDedup::gc_prologue(true); 3343 } 3344 3345 ~G1StringDedupCleaningTask() { 3346 StringDedup::gc_epilogue(); 3347 } 3348 3349 void work(uint worker_id) { 3350 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3351 { 3352 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3353 StringDedupQueue::unlink_or_oops_do(&cl); 3354 } 3355 { 3356 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3357 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3358 } 3359 } 3360 }; 3361 3362 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3363 OopClosure* keep_alive, 3364 G1GCPhaseTimes* phase_times) { 3365 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3366 workers()->run_task(&cl); 3367 } 3368 3369 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3370 private: 3371 G1RedirtyCardsQueueSet* _qset; 3372 G1CollectedHeap* _g1h; 3373 BufferNode* volatile _nodes; 3374 3375 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3376 size_t buffer_size = _qset->buffer_size(); 3377 BufferNode* next = Atomic::load(&_nodes); 3378 while (next != NULL) { 3379 BufferNode* node = next; 3380 next = Atomic::cmpxchg(&_nodes, node, node->next()); 3381 if (next == node) { 3382 cl->apply_to_buffer(node, buffer_size, worker_id); 3383 next = node->next(); 3384 } 3385 } 3386 } 3387 3388 public: 3389 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3390 AbstractGangTask("Redirty Cards"), 3391 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3392 3393 virtual void work(uint worker_id) { 3394 G1GCPhaseTimes* p = _g1h->phase_times(); 3395 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3396 3397 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3398 par_apply(&cl, worker_id); 3399 3400 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3401 } 3402 }; 3403 3404 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3405 double redirty_logged_cards_start = os::elapsedTime(); 3406 3407 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3408 workers()->run_task(&redirty_task); 3409 3410 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3411 dcq.merge_bufferlists(rdcqs); 3412 3413 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3414 } 3415 3416 // Weak Reference Processing support 3417 3418 bool G1STWIsAliveClosure::do_object_b(oop p) { 3419 // An object is reachable if it is outside the collection set, 3420 // or is inside and copied. 3421 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3422 } 3423 3424 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3425 assert(obj != NULL, "must not be NULL"); 3426 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3427 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3428 // may falsely indicate that this is not the case here: however the collection set only 3429 // contains old regions when concurrent mark is not running. 3430 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3431 } 3432 3433 // Non Copying Keep Alive closure 3434 class G1KeepAliveClosure: public OopClosure { 3435 G1CollectedHeap*_g1h; 3436 public: 3437 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3438 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3439 void do_oop(oop* p) { 3440 oop obj = *p; 3441 assert(obj != NULL, "the caller should have filtered out NULL values"); 3442 3443 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3444 if (!region_attr.is_in_cset_or_humongous()) { 3445 return; 3446 } 3447 if (region_attr.is_in_cset()) { 3448 assert( obj->is_forwarded(), "invariant" ); 3449 *p = obj->forwardee(); 3450 } else { 3451 assert(!obj->is_forwarded(), "invariant" ); 3452 assert(region_attr.is_humongous(), 3453 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3454 _g1h->set_humongous_is_live(obj); 3455 } 3456 } 3457 }; 3458 3459 // Copying Keep Alive closure - can be called from both 3460 // serial and parallel code as long as different worker 3461 // threads utilize different G1ParScanThreadState instances 3462 // and different queues. 3463 3464 class G1CopyingKeepAliveClosure: public OopClosure { 3465 G1CollectedHeap* _g1h; 3466 G1ParScanThreadState* _par_scan_state; 3467 3468 public: 3469 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3470 G1ParScanThreadState* pss): 3471 _g1h(g1h), 3472 _par_scan_state(pss) 3473 {} 3474 3475 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3476 virtual void do_oop( oop* p) { do_oop_work(p); } 3477 3478 template <class T> void do_oop_work(T* p) { 3479 oop obj = RawAccess<>::oop_load(p); 3480 3481 if (_g1h->is_in_cset_or_humongous(obj)) { 3482 // If the referent object has been forwarded (either copied 3483 // to a new location or to itself in the event of an 3484 // evacuation failure) then we need to update the reference 3485 // field and, if both reference and referent are in the G1 3486 // heap, update the RSet for the referent. 3487 // 3488 // If the referent has not been forwarded then we have to keep 3489 // it alive by policy. Therefore we have copy the referent. 3490 // 3491 // When the queue is drained (after each phase of reference processing) 3492 // the object and it's followers will be copied, the reference field set 3493 // to point to the new location, and the RSet updated. 3494 _par_scan_state->push_on_queue(p); 3495 } 3496 } 3497 }; 3498 3499 // Serial drain queue closure. Called as the 'complete_gc' 3500 // closure for each discovered list in some of the 3501 // reference processing phases. 3502 3503 class G1STWDrainQueueClosure: public VoidClosure { 3504 protected: 3505 G1CollectedHeap* _g1h; 3506 G1ParScanThreadState* _par_scan_state; 3507 3508 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3509 3510 public: 3511 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3512 _g1h(g1h), 3513 _par_scan_state(pss) 3514 { } 3515 3516 void do_void() { 3517 G1ParScanThreadState* const pss = par_scan_state(); 3518 pss->trim_queue(); 3519 } 3520 }; 3521 3522 // Parallel Reference Processing closures 3523 3524 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3525 // processing during G1 evacuation pauses. 3526 3527 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3528 private: 3529 G1CollectedHeap* _g1h; 3530 G1ParScanThreadStateSet* _pss; 3531 RefToScanQueueSet* _queues; 3532 WorkGang* _workers; 3533 3534 public: 3535 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3536 G1ParScanThreadStateSet* per_thread_states, 3537 WorkGang* workers, 3538 RefToScanQueueSet *task_queues) : 3539 _g1h(g1h), 3540 _pss(per_thread_states), 3541 _queues(task_queues), 3542 _workers(workers) 3543 { 3544 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3545 } 3546 3547 // Executes the given task using concurrent marking worker threads. 3548 virtual void execute(ProcessTask& task, uint ergo_workers); 3549 }; 3550 3551 // Gang task for possibly parallel reference processing 3552 3553 class G1STWRefProcTaskProxy: public AbstractGangTask { 3554 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3555 ProcessTask& _proc_task; 3556 G1CollectedHeap* _g1h; 3557 G1ParScanThreadStateSet* _pss; 3558 RefToScanQueueSet* _task_queues; 3559 ParallelTaskTerminator* _terminator; 3560 3561 public: 3562 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3563 G1CollectedHeap* g1h, 3564 G1ParScanThreadStateSet* per_thread_states, 3565 RefToScanQueueSet *task_queues, 3566 ParallelTaskTerminator* terminator) : 3567 AbstractGangTask("Process reference objects in parallel"), 3568 _proc_task(proc_task), 3569 _g1h(g1h), 3570 _pss(per_thread_states), 3571 _task_queues(task_queues), 3572 _terminator(terminator) 3573 {} 3574 3575 virtual void work(uint worker_id) { 3576 // The reference processing task executed by a single worker. 3577 ResourceMark rm; 3578 HandleMark hm; 3579 3580 G1STWIsAliveClosure is_alive(_g1h); 3581 3582 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3583 pss->set_ref_discoverer(NULL); 3584 3585 // Keep alive closure. 3586 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3587 3588 // Complete GC closure 3589 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3590 3591 // Call the reference processing task's work routine. 3592 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3593 3594 // Note we cannot assert that the refs array is empty here as not all 3595 // of the processing tasks (specifically phase2 - pp2_work) execute 3596 // the complete_gc closure (which ordinarily would drain the queue) so 3597 // the queue may not be empty. 3598 } 3599 }; 3600 3601 // Driver routine for parallel reference processing. 3602 // Creates an instance of the ref processing gang 3603 // task and has the worker threads execute it. 3604 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3605 assert(_workers != NULL, "Need parallel worker threads."); 3606 3607 assert(_workers->active_workers() >= ergo_workers, 3608 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3609 ergo_workers, _workers->active_workers()); 3610 TaskTerminator terminator(ergo_workers, _queues); 3611 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3612 3613 _workers->run_task(&proc_task_proxy, ergo_workers); 3614 } 3615 3616 // End of weak reference support closures 3617 3618 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3619 double ref_proc_start = os::elapsedTime(); 3620 3621 ReferenceProcessor* rp = _ref_processor_stw; 3622 assert(rp->discovery_enabled(), "should have been enabled"); 3623 3624 // Closure to test whether a referent is alive. 3625 G1STWIsAliveClosure is_alive(this); 3626 3627 // Even when parallel reference processing is enabled, the processing 3628 // of JNI refs is serial and performed serially by the current thread 3629 // rather than by a worker. The following PSS will be used for processing 3630 // JNI refs. 3631 3632 // Use only a single queue for this PSS. 3633 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3634 pss->set_ref_discoverer(NULL); 3635 assert(pss->queue_is_empty(), "pre-condition"); 3636 3637 // Keep alive closure. 3638 G1CopyingKeepAliveClosure keep_alive(this, pss); 3639 3640 // Serial Complete GC closure 3641 G1STWDrainQueueClosure drain_queue(this, pss); 3642 3643 // Setup the soft refs policy... 3644 rp->setup_policy(false); 3645 3646 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3647 3648 ReferenceProcessorStats stats; 3649 if (!rp->processing_is_mt()) { 3650 // Serial reference processing... 3651 stats = rp->process_discovered_references(&is_alive, 3652 &keep_alive, 3653 &drain_queue, 3654 NULL, 3655 pt); 3656 } else { 3657 uint no_of_gc_workers = workers()->active_workers(); 3658 3659 // Parallel reference processing 3660 assert(no_of_gc_workers <= rp->max_num_queues(), 3661 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3662 no_of_gc_workers, rp->max_num_queues()); 3663 3664 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3665 stats = rp->process_discovered_references(&is_alive, 3666 &keep_alive, 3667 &drain_queue, 3668 &par_task_executor, 3669 pt); 3670 } 3671 3672 _gc_tracer_stw->report_gc_reference_stats(stats); 3673 3674 // We have completed copying any necessary live referent objects. 3675 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3676 3677 make_pending_list_reachable(); 3678 3679 assert(!rp->discovery_enabled(), "Postcondition"); 3680 rp->verify_no_references_recorded(); 3681 3682 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3683 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3684 } 3685 3686 void G1CollectedHeap::make_pending_list_reachable() { 3687 if (collector_state()->in_initial_mark_gc()) { 3688 oop pll_head = Universe::reference_pending_list(); 3689 if (pll_head != NULL) { 3690 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3691 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3692 } 3693 } 3694 } 3695 3696 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3697 Ticks start = Ticks::now(); 3698 per_thread_states->flush(); 3699 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds()); 3700 } 3701 3702 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3703 _bytes_used_during_gc = 0; 3704 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 if (termination_phase == G1GCPhaseTimes::Termination) { 3770 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3771 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3772 } else { 3773 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3774 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3775 } 3776 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3777 } 3778 3779 virtual void start_work(uint worker_id) { } 3780 3781 virtual void end_work(uint worker_id) { } 3782 3783 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3784 3785 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3786 3787 public: 3788 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3789 AbstractGangTask(name), 3790 _g1h(G1CollectedHeap::heap()), 3791 _per_thread_states(per_thread_states), 3792 _task_queues(task_queues), 3793 _terminator(num_workers, _task_queues), 3794 _num_workers(num_workers) 3795 { } 3796 3797 void work(uint worker_id) { 3798 start_work(worker_id); 3799 3800 { 3801 ResourceMark rm; 3802 HandleMark hm; 3803 3804 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3805 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3806 3807 scan_roots(pss, worker_id); 3808 evacuate_live_objects(pss, worker_id); 3809 } 3810 3811 end_work(worker_id); 3812 } 3813 }; 3814 3815 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3816 G1RootProcessor* _root_processor; 3817 3818 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3819 _root_processor->evacuate_roots(pss, worker_id); 3820 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3821 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3822 } 3823 3824 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3825 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3826 } 3827 3828 void start_work(uint worker_id) { 3829 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3830 } 3831 3832 void end_work(uint worker_id) { 3833 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3834 } 3835 3836 public: 3837 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3838 G1ParScanThreadStateSet* per_thread_states, 3839 RefToScanQueueSet* task_queues, 3840 G1RootProcessor* root_processor, 3841 uint num_workers) : 3842 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3843 _root_processor(root_processor) 3844 { } 3845 }; 3846 3847 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3848 G1GCPhaseTimes* p = phase_times(); 3849 3850 { 3851 Ticks start = Ticks::now(); 3852 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3853 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3854 } 3855 3856 Tickspan task_time; 3857 const uint num_workers = workers()->active_workers(); 3858 3859 Ticks start_processing = Ticks::now(); 3860 { 3861 G1RootProcessor root_processor(this, num_workers); 3862 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3863 task_time = run_task(&g1_par_task); 3864 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3865 // To extract its code root fixup time we measure total time of this scope and 3866 // subtract from the time the WorkGang task took. 3867 } 3868 Tickspan total_processing = Ticks::now() - start_processing; 3869 3870 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3871 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3872 } 3873 3874 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3875 3876 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3877 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3878 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3879 } 3880 3881 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3882 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3883 } 3884 3885 public: 3886 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3887 RefToScanQueueSet* queues, 3888 uint num_workers) : 3889 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3890 } 3891 }; 3892 3893 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3894 class G1MarkScope : public MarkScope { }; 3895 3896 Tickspan task_time; 3897 3898 Ticks start_processing = Ticks::now(); 3899 { 3900 G1MarkScope code_mark_scope; 3901 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3902 task_time = run_task(&task); 3903 // See comment in evacuate_collection_set() for the reason of the scope. 3904 } 3905 Tickspan total_processing = Ticks::now() - start_processing; 3906 3907 G1GCPhaseTimes* p = phase_times(); 3908 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3909 } 3910 3911 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3912 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3913 3914 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3915 3916 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3917 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3918 3919 if (time_left_ms < 0 || 3920 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3921 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3922 _collection_set.optional_region_length(), time_left_ms); 3923 break; 3924 } 3925 3926 { 3927 Ticks start = Ticks::now(); 3928 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3929 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3930 } 3931 3932 { 3933 Ticks start = Ticks::now(); 3934 evacuate_next_optional_regions(per_thread_states); 3935 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3936 } 3937 } 3938 3939 _collection_set.abandon_optional_collection_set(per_thread_states); 3940 } 3941 3942 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3943 G1RedirtyCardsQueueSet* rdcqs, 3944 G1ParScanThreadStateSet* per_thread_states) { 3945 G1GCPhaseTimes* p = phase_times(); 3946 3947 rem_set()->cleanup_after_scan_heap_roots(); 3948 3949 // Process any discovered reference objects - we have 3950 // to do this _before_ we retire the GC alloc regions 3951 // as we may have to copy some 'reachable' referent 3952 // objects (and their reachable sub-graphs) that were 3953 // not copied during the pause. 3954 process_discovered_references(per_thread_states); 3955 3956 G1STWIsAliveClosure is_alive(this); 3957 G1KeepAliveClosure keep_alive(this); 3958 3959 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times()); 3960 3961 if (G1StringDedup::is_enabled()) { 3962 double string_dedup_time_ms = os::elapsedTime(); 3963 3964 string_dedup_cleaning(&is_alive, &keep_alive, p); 3965 3966 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3967 p->record_string_deduplication_time(string_cleanup_time_ms); 3968 } 3969 3970 _allocator->release_gc_alloc_regions(evacuation_info); 3971 3972 if (evacuation_failed()) { 3973 restore_after_evac_failure(rdcqs); 3974 3975 // Reset the G1EvacuationFailureALot counters and flags 3976 NOT_PRODUCT(reset_evacuation_should_fail();) 3977 3978 double recalculate_used_start = os::elapsedTime(); 3979 set_used(recalculate_used()); 3980 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3981 3982 if (_archive_allocator != NULL) { 3983 _archive_allocator->clear_used(); 3984 } 3985 for (uint i = 0; i < ParallelGCThreads; i++) { 3986 if (_evacuation_failed_info_array[i].has_failed()) { 3987 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3988 } 3989 } 3990 } else { 3991 // The "used" of the the collection set have already been subtracted 3992 // when they were freed. Add in the bytes used. 3993 increase_used(_bytes_used_during_gc); 3994 } 3995 3996 _preserved_marks_set.assert_empty(); 3997 3998 merge_per_thread_state_info(per_thread_states); 3999 4000 // Reset and re-enable the hot card cache. 4001 // Note the counts for the cards in the regions in the 4002 // collection set are reset when the collection set is freed. 4003 _hot_card_cache->reset_hot_cache(); 4004 _hot_card_cache->set_use_cache(true); 4005 4006 purge_code_root_memory(); 4007 4008 redirty_logged_cards(rdcqs); 4009 4010 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4011 4012 eagerly_reclaim_humongous_regions(); 4013 4014 record_obj_copy_mem_stats(); 4015 4016 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4017 evacuation_info.set_bytes_used(_bytes_used_during_gc); 4018 4019 #if COMPILER2_OR_JVMCI 4020 double start = os::elapsedTime(); 4021 DerivedPointerTable::update_pointers(); 4022 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4023 #endif 4024 policy()->print_age_table(); 4025 } 4026 4027 void G1CollectedHeap::record_obj_copy_mem_stats() { 4028 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4029 4030 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4031 create_g1_evac_summary(&_old_evac_stats)); 4032 } 4033 4034 void G1CollectedHeap::free_region(HeapRegion* hr, 4035 FreeRegionList* free_list, 4036 bool skip_remset, 4037 bool skip_hot_card_cache, 4038 bool locked) { 4039 assert(!hr->is_free(), "the region should not be free"); 4040 assert(!hr->is_empty(), "the region should not be empty"); 4041 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4042 assert(free_list != NULL, "pre-condition"); 4043 4044 if (G1VerifyBitmaps) { 4045 MemRegion mr(hr->bottom(), hr->end()); 4046 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4047 } 4048 4049 // Clear the card counts for this region. 4050 // Note: we only need to do this if the region is not young 4051 // (since we don't refine cards in young regions). 4052 if (!skip_hot_card_cache && !hr->is_young()) { 4053 _hot_card_cache->reset_card_counts(hr); 4054 } 4055 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4056 _policy->remset_tracker()->update_at_free(hr); 4057 free_list->add_ordered(hr); 4058 } 4059 4060 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4061 FreeRegionList* free_list) { 4062 assert(hr->is_humongous(), "this is only for humongous regions"); 4063 assert(free_list != NULL, "pre-condition"); 4064 hr->clear_humongous(); 4065 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 4066 } 4067 4068 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4069 const uint humongous_regions_removed) { 4070 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4071 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4072 _old_set.bulk_remove(old_regions_removed); 4073 _humongous_set.bulk_remove(humongous_regions_removed); 4074 } 4075 4076 } 4077 4078 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4079 assert(list != NULL, "list can't be null"); 4080 if (!list->is_empty()) { 4081 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4082 _hrm->insert_list_into_free_list(list); 4083 } 4084 } 4085 4086 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4087 decrease_used(bytes); 4088 } 4089 4090 class G1FreeCollectionSetTask : public AbstractGangTask { 4091 private: 4092 4093 // Closure applied to all regions in the collection set to do work that needs to 4094 // be done serially in a single thread. 4095 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4096 private: 4097 G1EvacuationInfo* _evacuation_info; 4098 const size_t* _surviving_young_words; 4099 4100 // Bytes used in successfully evacuated regions before the evacuation. 4101 size_t _before_used_bytes; 4102 // Bytes used in unsucessfully evacuated regions before the evacuation 4103 size_t _after_used_bytes; 4104 4105 size_t _bytes_allocated_in_old_since_last_gc; 4106 4107 size_t _failure_used_words; 4108 size_t _failure_waste_words; 4109 4110 FreeRegionList _local_free_list; 4111 public: 4112 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4113 HeapRegionClosure(), 4114 _evacuation_info(evacuation_info), 4115 _surviving_young_words(surviving_young_words), 4116 _before_used_bytes(0), 4117 _after_used_bytes(0), 4118 _bytes_allocated_in_old_since_last_gc(0), 4119 _failure_used_words(0), 4120 _failure_waste_words(0), 4121 _local_free_list("Local Region List for CSet Freeing") { 4122 } 4123 4124 virtual bool do_heap_region(HeapRegion* r) { 4125 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4126 4127 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4128 g1h->clear_region_attr(r); 4129 4130 if (r->is_young()) { 4131 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(), 4132 "Young index %u is wrong for region %u of type %s with %u young regions", 4133 r->young_index_in_cset(), 4134 r->hrm_index(), 4135 r->get_type_str(), 4136 g1h->collection_set()->young_region_length()); 4137 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4138 r->record_surv_words_in_group(words_survived); 4139 } 4140 4141 if (!r->evacuation_failed()) { 4142 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4143 _before_used_bytes += r->used(); 4144 g1h->free_region(r, 4145 &_local_free_list, 4146 true, /* skip_remset */ 4147 true, /* skip_hot_card_cache */ 4148 true /* locked */); 4149 } else { 4150 r->uninstall_surv_rate_group(); 4151 r->clear_young_index_in_cset(); 4152 r->set_evacuation_failed(false); 4153 // When moving a young gen region to old gen, we "allocate" that whole region 4154 // there. This is in addition to any already evacuated objects. Notify the 4155 // policy about that. 4156 // Old gen regions do not cause an additional allocation: both the objects 4157 // still in the region and the ones already moved are accounted for elsewhere. 4158 if (r->is_young()) { 4159 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4160 } 4161 // The region is now considered to be old. 4162 r->set_old(); 4163 // Do some allocation statistics accounting. Regions that failed evacuation 4164 // are always made old, so there is no need to update anything in the young 4165 // gen statistics, but we need to update old gen statistics. 4166 size_t used_words = r->marked_bytes() / HeapWordSize; 4167 4168 _failure_used_words += used_words; 4169 _failure_waste_words += HeapRegion::GrainWords - used_words; 4170 4171 g1h->old_set_add(r); 4172 _after_used_bytes += r->used(); 4173 } 4174 return false; 4175 } 4176 4177 void complete_work() { 4178 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4179 4180 _evacuation_info->set_regions_freed(_local_free_list.length()); 4181 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4182 4183 g1h->prepend_to_freelist(&_local_free_list); 4184 g1h->decrement_summary_bytes(_before_used_bytes); 4185 4186 G1Policy* policy = g1h->policy(); 4187 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4188 4189 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4190 } 4191 }; 4192 4193 G1CollectionSet* _collection_set; 4194 G1SerialFreeCollectionSetClosure _cl; 4195 const size_t* _surviving_young_words; 4196 4197 size_t _rs_length; 4198 4199 volatile jint _serial_work_claim; 4200 4201 struct WorkItem { 4202 uint region_idx; 4203 bool is_young; 4204 bool evacuation_failed; 4205 4206 WorkItem(HeapRegion* r) { 4207 region_idx = r->hrm_index(); 4208 is_young = r->is_young(); 4209 evacuation_failed = r->evacuation_failed(); 4210 } 4211 }; 4212 4213 volatile size_t _parallel_work_claim; 4214 size_t _num_work_items; 4215 WorkItem* _work_items; 4216 4217 void do_serial_work() { 4218 // Need to grab the lock to be allowed to modify the old region list. 4219 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4220 _collection_set->iterate(&_cl); 4221 } 4222 4223 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4224 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4225 4226 HeapRegion* r = g1h->region_at(region_idx); 4227 assert(!g1h->is_on_master_free_list(r), "sanity"); 4228 4229 Atomic::add(&_rs_length, r->rem_set()->occupied_locked()); 4230 4231 if (!is_young) { 4232 g1h->hot_card_cache()->reset_card_counts(r); 4233 } 4234 4235 if (!evacuation_failed) { 4236 r->rem_set()->clear_locked(); 4237 } 4238 } 4239 4240 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4241 private: 4242 size_t _cur_idx; 4243 WorkItem* _work_items; 4244 public: 4245 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4246 4247 virtual bool do_heap_region(HeapRegion* r) { 4248 _work_items[_cur_idx++] = WorkItem(r); 4249 return false; 4250 } 4251 }; 4252 4253 void prepare_work() { 4254 G1PrepareFreeCollectionSetClosure cl(_work_items); 4255 _collection_set->iterate(&cl); 4256 } 4257 4258 void complete_work() { 4259 _cl.complete_work(); 4260 4261 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4262 policy->record_rs_length(_rs_length); 4263 policy->cset_regions_freed(); 4264 } 4265 public: 4266 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4267 AbstractGangTask("G1 Free Collection Set"), 4268 _collection_set(collection_set), 4269 _cl(evacuation_info, surviving_young_words), 4270 _surviving_young_words(surviving_young_words), 4271 _rs_length(0), 4272 _serial_work_claim(0), 4273 _parallel_work_claim(0), 4274 _num_work_items(collection_set->region_length()), 4275 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4276 prepare_work(); 4277 } 4278 4279 ~G1FreeCollectionSetTask() { 4280 complete_work(); 4281 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4282 } 4283 4284 // Chunk size for work distribution. The chosen value has been determined experimentally 4285 // to be a good tradeoff between overhead and achievable parallelism. 4286 static uint chunk_size() { return 32; } 4287 4288 virtual void work(uint worker_id) { 4289 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4290 4291 // Claim serial work. 4292 if (_serial_work_claim == 0) { 4293 jint value = Atomic::add(&_serial_work_claim, 1) - 1; 4294 if (value == 0) { 4295 double serial_time = os::elapsedTime(); 4296 do_serial_work(); 4297 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4298 } 4299 } 4300 4301 // Start parallel work. 4302 double young_time = 0.0; 4303 bool has_young_time = false; 4304 double non_young_time = 0.0; 4305 bool has_non_young_time = false; 4306 4307 while (true) { 4308 size_t end = Atomic::add(&_parallel_work_claim, chunk_size()); 4309 size_t cur = end - chunk_size(); 4310 4311 if (cur >= _num_work_items) { 4312 break; 4313 } 4314 4315 EventGCPhaseParallel event; 4316 double start_time = os::elapsedTime(); 4317 4318 end = MIN2(end, _num_work_items); 4319 4320 for (; cur < end; cur++) { 4321 bool is_young = _work_items[cur].is_young; 4322 4323 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4324 4325 double end_time = os::elapsedTime(); 4326 double time_taken = end_time - start_time; 4327 if (is_young) { 4328 young_time += time_taken; 4329 has_young_time = true; 4330 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4331 } else { 4332 non_young_time += time_taken; 4333 has_non_young_time = true; 4334 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4335 } 4336 start_time = end_time; 4337 } 4338 } 4339 4340 if (has_young_time) { 4341 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4342 } 4343 if (has_non_young_time) { 4344 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4345 } 4346 } 4347 }; 4348 4349 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4350 _eden.clear(); 4351 4352 double free_cset_start_time = os::elapsedTime(); 4353 4354 { 4355 uint const num_regions = _collection_set.region_length(); 4356 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4357 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4358 4359 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4360 4361 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4362 cl.name(), num_workers, num_regions); 4363 workers()->run_task(&cl, num_workers); 4364 } 4365 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4366 4367 collection_set->clear(); 4368 } 4369 4370 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4371 private: 4372 FreeRegionList* _free_region_list; 4373 HeapRegionSet* _proxy_set; 4374 uint _humongous_objects_reclaimed; 4375 uint _humongous_regions_reclaimed; 4376 size_t _freed_bytes; 4377 public: 4378 4379 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4380 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4381 } 4382 4383 virtual bool do_heap_region(HeapRegion* r) { 4384 if (!r->is_starts_humongous()) { 4385 return false; 4386 } 4387 4388 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4389 4390 oop obj = (oop)r->bottom(); 4391 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4392 4393 // The following checks whether the humongous object is live are sufficient. 4394 // The main additional check (in addition to having a reference from the roots 4395 // or the young gen) is whether the humongous object has a remembered set entry. 4396 // 4397 // A humongous object cannot be live if there is no remembered set for it 4398 // because: 4399 // - there can be no references from within humongous starts regions referencing 4400 // the object because we never allocate other objects into them. 4401 // (I.e. there are no intra-region references that may be missed by the 4402 // remembered set) 4403 // - as soon there is a remembered set entry to the humongous starts region 4404 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4405 // until the end of a concurrent mark. 4406 // 4407 // It is not required to check whether the object has been found dead by marking 4408 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4409 // all objects allocated during that time are considered live. 4410 // SATB marking is even more conservative than the remembered set. 4411 // So if at this point in the collection there is no remembered set entry, 4412 // nobody has a reference to it. 4413 // At the start of collection we flush all refinement logs, and remembered sets 4414 // are completely up-to-date wrt to references to the humongous object. 4415 // 4416 // Other implementation considerations: 4417 // - never consider object arrays at this time because they would pose 4418 // considerable effort for cleaning up the the remembered sets. This is 4419 // required because stale remembered sets might reference locations that 4420 // are currently allocated into. 4421 uint region_idx = r->hrm_index(); 4422 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4423 !r->rem_set()->is_empty()) { 4424 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", 4425 region_idx, 4426 (size_t)obj->size() * HeapWordSize, 4427 p2i(r->bottom()), 4428 r->rem_set()->occupied(), 4429 r->rem_set()->strong_code_roots_list_length(), 4430 next_bitmap->is_marked(r->bottom()), 4431 g1h->is_humongous_reclaim_candidate(region_idx), 4432 obj->is_typeArray() 4433 ); 4434 return false; 4435 } 4436 4437 guarantee(obj->is_typeArray(), 4438 "Only eagerly reclaiming type arrays is supported, but the object " 4439 PTR_FORMAT " is not.", p2i(r->bottom())); 4440 4441 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", 4442 region_idx, 4443 (size_t)obj->size() * HeapWordSize, 4444 p2i(r->bottom()), 4445 r->rem_set()->occupied(), 4446 r->rem_set()->strong_code_roots_list_length(), 4447 next_bitmap->is_marked(r->bottom()), 4448 g1h->is_humongous_reclaim_candidate(region_idx), 4449 obj->is_typeArray() 4450 ); 4451 4452 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4453 cm->humongous_object_eagerly_reclaimed(r); 4454 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4455 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4456 region_idx, 4457 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4458 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4459 _humongous_objects_reclaimed++; 4460 do { 4461 HeapRegion* next = g1h->next_region_in_humongous(r); 4462 _freed_bytes += r->used(); 4463 r->set_containing_set(NULL); 4464 _humongous_regions_reclaimed++; 4465 g1h->free_humongous_region(r, _free_region_list); 4466 r = next; 4467 } while (r != NULL); 4468 4469 return false; 4470 } 4471 4472 uint humongous_objects_reclaimed() { 4473 return _humongous_objects_reclaimed; 4474 } 4475 4476 uint humongous_regions_reclaimed() { 4477 return _humongous_regions_reclaimed; 4478 } 4479 4480 size_t bytes_freed() const { 4481 return _freed_bytes; 4482 } 4483 }; 4484 4485 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4486 assert_at_safepoint_on_vm_thread(); 4487 4488 if (!G1EagerReclaimHumongousObjects || 4489 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4490 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4491 return; 4492 } 4493 4494 double start_time = os::elapsedTime(); 4495 4496 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4497 4498 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4499 heap_region_iterate(&cl); 4500 4501 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4502 4503 G1HRPrinter* hrp = hr_printer(); 4504 if (hrp->is_active()) { 4505 FreeRegionListIterator iter(&local_cleanup_list); 4506 while (iter.more_available()) { 4507 HeapRegion* hr = iter.get_next(); 4508 hrp->cleanup(hr); 4509 } 4510 } 4511 4512 prepend_to_freelist(&local_cleanup_list); 4513 decrement_summary_bytes(cl.bytes_freed()); 4514 4515 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4516 cl.humongous_objects_reclaimed()); 4517 } 4518 4519 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4520 public: 4521 virtual bool do_heap_region(HeapRegion* r) { 4522 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4523 G1CollectedHeap::heap()->clear_region_attr(r); 4524 r->clear_young_index_in_cset(); 4525 return false; 4526 } 4527 }; 4528 4529 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4530 G1AbandonCollectionSetClosure cl; 4531 collection_set_iterate_all(&cl); 4532 4533 collection_set->clear(); 4534 collection_set->stop_incremental_building(); 4535 } 4536 4537 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4538 return _allocator->is_retained_old_region(hr); 4539 } 4540 4541 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4542 _eden.add(hr); 4543 _policy->set_region_eden(hr); 4544 } 4545 4546 #ifdef ASSERT 4547 4548 class NoYoungRegionsClosure: public HeapRegionClosure { 4549 private: 4550 bool _success; 4551 public: 4552 NoYoungRegionsClosure() : _success(true) { } 4553 bool do_heap_region(HeapRegion* r) { 4554 if (r->is_young()) { 4555 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4556 p2i(r->bottom()), p2i(r->end())); 4557 _success = false; 4558 } 4559 return false; 4560 } 4561 bool success() { return _success; } 4562 }; 4563 4564 bool G1CollectedHeap::check_young_list_empty() { 4565 bool ret = (young_regions_count() == 0); 4566 4567 NoYoungRegionsClosure closure; 4568 heap_region_iterate(&closure); 4569 ret = ret && closure.success(); 4570 4571 return ret; 4572 } 4573 4574 #endif // ASSERT 4575 4576 class TearDownRegionSetsClosure : public HeapRegionClosure { 4577 HeapRegionSet *_old_set; 4578 4579 public: 4580 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4581 4582 bool do_heap_region(HeapRegion* r) { 4583 if (r->is_old()) { 4584 _old_set->remove(r); 4585 } else if(r->is_young()) { 4586 r->uninstall_surv_rate_group(); 4587 } else { 4588 // We ignore free regions, we'll empty the free list afterwards. 4589 // We ignore humongous and archive regions, we're not tearing down these 4590 // sets. 4591 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4592 "it cannot be another type"); 4593 } 4594 return false; 4595 } 4596 4597 ~TearDownRegionSetsClosure() { 4598 assert(_old_set->is_empty(), "post-condition"); 4599 } 4600 }; 4601 4602 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4603 assert_at_safepoint_on_vm_thread(); 4604 4605 if (!free_list_only) { 4606 TearDownRegionSetsClosure cl(&_old_set); 4607 heap_region_iterate(&cl); 4608 4609 // Note that emptying the _young_list is postponed and instead done as 4610 // the first step when rebuilding the regions sets again. The reason for 4611 // this is that during a full GC string deduplication needs to know if 4612 // a collected region was young or old when the full GC was initiated. 4613 } 4614 _hrm->remove_all_free_regions(); 4615 } 4616 4617 void G1CollectedHeap::increase_used(size_t bytes) { 4618 _summary_bytes_used += bytes; 4619 } 4620 4621 void G1CollectedHeap::decrease_used(size_t bytes) { 4622 assert(_summary_bytes_used >= bytes, 4623 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4624 _summary_bytes_used, bytes); 4625 _summary_bytes_used -= bytes; 4626 } 4627 4628 void G1CollectedHeap::set_used(size_t bytes) { 4629 _summary_bytes_used = bytes; 4630 } 4631 4632 class RebuildRegionSetsClosure : public HeapRegionClosure { 4633 private: 4634 bool _free_list_only; 4635 4636 HeapRegionSet* _old_set; 4637 HeapRegionManager* _hrm; 4638 4639 size_t _total_used; 4640 4641 public: 4642 RebuildRegionSetsClosure(bool free_list_only, 4643 HeapRegionSet* old_set, 4644 HeapRegionManager* hrm) : 4645 _free_list_only(free_list_only), 4646 _old_set(old_set), _hrm(hrm), _total_used(0) { 4647 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4648 if (!free_list_only) { 4649 assert(_old_set->is_empty(), "pre-condition"); 4650 } 4651 } 4652 4653 bool do_heap_region(HeapRegion* r) { 4654 if (r->is_empty()) { 4655 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4656 // Add free regions to the free list 4657 r->set_free(); 4658 _hrm->insert_into_free_list(r); 4659 } else if (!_free_list_only) { 4660 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4661 4662 if (r->is_archive() || r->is_humongous()) { 4663 // We ignore archive and humongous regions. We left these sets unchanged. 4664 } else { 4665 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4666 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4667 r->move_to_old(); 4668 _old_set->add(r); 4669 } 4670 _total_used += r->used(); 4671 } 4672 4673 return false; 4674 } 4675 4676 size_t total_used() { 4677 return _total_used; 4678 } 4679 }; 4680 4681 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4682 assert_at_safepoint_on_vm_thread(); 4683 4684 if (!free_list_only) { 4685 _eden.clear(); 4686 _survivor.clear(); 4687 } 4688 4689 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4690 heap_region_iterate(&cl); 4691 4692 if (!free_list_only) { 4693 set_used(cl.total_used()); 4694 if (_archive_allocator != NULL) { 4695 _archive_allocator->clear_used(); 4696 } 4697 } 4698 assert_used_and_recalculate_used_equal(this); 4699 } 4700 4701 // Methods for the mutator alloc region 4702 4703 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4704 bool force, 4705 uint node_index) { 4706 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4707 bool should_allocate = policy()->should_allocate_mutator_region(); 4708 if (force || should_allocate) { 4709 HeapRegion* new_alloc_region = new_region(word_size, 4710 HeapRegionType::Eden, 4711 false /* do_expand */, 4712 node_index); 4713 if (new_alloc_region != NULL) { 4714 set_region_short_lived_locked(new_alloc_region); 4715 _hr_printer.alloc(new_alloc_region, !should_allocate); 4716 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4717 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4718 return new_alloc_region; 4719 } 4720 } 4721 return NULL; 4722 } 4723 4724 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4725 size_t allocated_bytes) { 4726 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4727 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4728 4729 collection_set()->add_eden_region(alloc_region); 4730 increase_used(allocated_bytes); 4731 _eden.add_used_bytes(allocated_bytes); 4732 _hr_printer.retire(alloc_region); 4733 4734 // We update the eden sizes here, when the region is retired, 4735 // instead of when it's allocated, since this is the point that its 4736 // used space has been recorded in _summary_bytes_used. 4737 g1mm()->update_eden_size(); 4738 } 4739 4740 // Methods for the GC alloc regions 4741 4742 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4743 if (dest.is_old()) { 4744 return true; 4745 } else { 4746 return survivor_regions_count() < policy()->max_survivor_regions(); 4747 } 4748 } 4749 4750 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4751 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4752 4753 if (!has_more_regions(dest)) { 4754 return NULL; 4755 } 4756 4757 HeapRegionType type; 4758 if (dest.is_young()) { 4759 type = HeapRegionType::Survivor; 4760 } else { 4761 type = HeapRegionType::Old; 4762 } 4763 4764 HeapRegion* new_alloc_region = new_region(word_size, 4765 type, 4766 true /* do_expand */, 4767 node_index); 4768 4769 if (new_alloc_region != NULL) { 4770 if (type.is_survivor()) { 4771 new_alloc_region->set_survivor(); 4772 _survivor.add(new_alloc_region); 4773 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4774 } else { 4775 new_alloc_region->set_old(); 4776 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4777 } 4778 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4779 register_region_with_region_attr(new_alloc_region); 4780 _hr_printer.alloc(new_alloc_region); 4781 return new_alloc_region; 4782 } 4783 return NULL; 4784 } 4785 4786 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4787 size_t allocated_bytes, 4788 G1HeapRegionAttr dest) { 4789 _bytes_used_during_gc += allocated_bytes; 4790 if (dest.is_old()) { 4791 old_set_add(alloc_region); 4792 } else { 4793 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4794 _survivor.add_used_bytes(allocated_bytes); 4795 } 4796 4797 bool const during_im = collector_state()->in_initial_mark_gc(); 4798 if (during_im && allocated_bytes > 0) { 4799 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4800 } 4801 _hr_printer.retire(alloc_region); 4802 } 4803 4804 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4805 bool expanded = false; 4806 uint index = _hrm->find_highest_free(&expanded); 4807 4808 if (index != G1_NO_HRM_INDEX) { 4809 if (expanded) { 4810 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4811 HeapRegion::GrainWords * HeapWordSize); 4812 } 4813 _hrm->allocate_free_regions_starting_at(index, 1); 4814 return region_at(index); 4815 } 4816 return NULL; 4817 } 4818 4819 // Optimized nmethod scanning 4820 4821 class RegisterNMethodOopClosure: public OopClosure { 4822 G1CollectedHeap* _g1h; 4823 nmethod* _nm; 4824 4825 template <class T> void do_oop_work(T* p) { 4826 T heap_oop = RawAccess<>::oop_load(p); 4827 if (!CompressedOops::is_null(heap_oop)) { 4828 oop obj = CompressedOops::decode_not_null(heap_oop); 4829 HeapRegion* hr = _g1h->heap_region_containing(obj); 4830 assert(!hr->is_continues_humongous(), 4831 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4832 " starting at " HR_FORMAT, 4833 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4834 4835 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4836 hr->add_strong_code_root_locked(_nm); 4837 } 4838 } 4839 4840 public: 4841 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4842 _g1h(g1h), _nm(nm) {} 4843 4844 void do_oop(oop* p) { do_oop_work(p); } 4845 void do_oop(narrowOop* p) { do_oop_work(p); } 4846 }; 4847 4848 class UnregisterNMethodOopClosure: public OopClosure { 4849 G1CollectedHeap* _g1h; 4850 nmethod* _nm; 4851 4852 template <class T> void do_oop_work(T* p) { 4853 T heap_oop = RawAccess<>::oop_load(p); 4854 if (!CompressedOops::is_null(heap_oop)) { 4855 oop obj = CompressedOops::decode_not_null(heap_oop); 4856 HeapRegion* hr = _g1h->heap_region_containing(obj); 4857 assert(!hr->is_continues_humongous(), 4858 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4859 " starting at " HR_FORMAT, 4860 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4861 4862 hr->remove_strong_code_root(_nm); 4863 } 4864 } 4865 4866 public: 4867 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4868 _g1h(g1h), _nm(nm) {} 4869 4870 void do_oop(oop* p) { do_oop_work(p); } 4871 void do_oop(narrowOop* p) { do_oop_work(p); } 4872 }; 4873 4874 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4875 guarantee(nm != NULL, "sanity"); 4876 RegisterNMethodOopClosure reg_cl(this, nm); 4877 nm->oops_do(®_cl); 4878 } 4879 4880 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4881 guarantee(nm != NULL, "sanity"); 4882 UnregisterNMethodOopClosure reg_cl(this, nm); 4883 nm->oops_do(®_cl, true); 4884 } 4885 4886 void G1CollectedHeap::purge_code_root_memory() { 4887 double purge_start = os::elapsedTime(); 4888 G1CodeRootSet::purge(); 4889 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4890 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4891 } 4892 4893 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4894 G1CollectedHeap* _g1h; 4895 4896 public: 4897 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4898 _g1h(g1h) {} 4899 4900 void do_code_blob(CodeBlob* cb) { 4901 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4902 if (nm == NULL) { 4903 return; 4904 } 4905 4906 _g1h->register_nmethod(nm); 4907 } 4908 }; 4909 4910 void G1CollectedHeap::rebuild_strong_code_roots() { 4911 RebuildStrongCodeRootClosure blob_cl(this); 4912 CodeCache::blobs_do(&blob_cl); 4913 } 4914 4915 void G1CollectedHeap::initialize_serviceability() { 4916 _g1mm->initialize_serviceability(); 4917 } 4918 4919 MemoryUsage G1CollectedHeap::memory_usage() { 4920 return _g1mm->memory_usage(); 4921 } 4922 4923 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4924 return _g1mm->memory_managers(); 4925 } 4926 4927 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4928 return _g1mm->memory_pools(); 4929 }