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->set_first_dead(top); 674 curr_region->set_end_of_live(top); 675 curr_region = next_region; 676 } 677 678 // Notify mark-sweep of the archive 679 G1ArchiveAllocator::set_range_archive(curr_range, open); 680 } 681 return true; 682 } 683 684 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 685 assert(!is_init_completed(), "Expect to be called at JVM init time"); 686 assert(ranges != NULL, "MemRegion array NULL"); 687 assert(count != 0, "No MemRegions provided"); 688 MemRegion reserved = _hrm->reserved(); 689 HeapWord *prev_last_addr = NULL; 690 HeapRegion* prev_last_region = NULL; 691 692 // For each MemRegion, create filler objects, if needed, in the G1 regions 693 // that contain the address range. The address range actually within the 694 // MemRegion will not be modified. That is assumed to have been initialized 695 // elsewhere, probably via an mmap of archived heap data. 696 MutexLocker x(Heap_lock); 697 for (size_t i = 0; i < count; i++) { 698 HeapWord* start_address = ranges[i].start(); 699 HeapWord* last_address = ranges[i].last(); 700 701 assert(reserved.contains(start_address) && reserved.contains(last_address), 702 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 703 p2i(start_address), p2i(last_address)); 704 assert(start_address > prev_last_addr, 705 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 706 p2i(start_address), p2i(prev_last_addr)); 707 708 HeapRegion* start_region = _hrm->addr_to_region(start_address); 709 HeapRegion* last_region = _hrm->addr_to_region(last_address); 710 HeapWord* bottom_address = start_region->bottom(); 711 712 // Check for a range beginning in the same region in which the 713 // previous one ended. 714 if (start_region == prev_last_region) { 715 bottom_address = prev_last_addr + 1; 716 } 717 718 // Verify that the regions were all marked as archive regions by 719 // alloc_archive_regions. 720 HeapRegion* curr_region = start_region; 721 while (curr_region != NULL) { 722 guarantee(curr_region->is_archive(), 723 "Expected archive region at index %u", curr_region->hrm_index()); 724 if (curr_region != last_region) { 725 curr_region = _hrm->next_region_in_heap(curr_region); 726 } else { 727 curr_region = NULL; 728 } 729 } 730 731 prev_last_addr = last_address; 732 prev_last_region = last_region; 733 734 // Fill the memory below the allocated range with dummy object(s), 735 // if the region bottom does not match the range start, or if the previous 736 // range ended within the same G1 region, and there is a gap. 737 if (start_address != bottom_address) { 738 size_t fill_size = pointer_delta(start_address, bottom_address); 739 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 740 increase_used(fill_size * HeapWordSize); 741 } 742 } 743 } 744 745 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 746 size_t desired_word_size, 747 size_t* actual_word_size) { 748 assert_heap_not_locked_and_not_at_safepoint(); 749 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 750 "be called for humongous allocation requests"); 751 752 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 753 754 if (result == NULL) { 755 *actual_word_size = desired_word_size; 756 result = attempt_allocation_slow(desired_word_size); 757 } 758 759 assert_heap_not_locked(); 760 if (result != NULL) { 761 assert(*actual_word_size != 0, "Actual size must have been set here"); 762 dirty_young_block(result, *actual_word_size); 763 } else { 764 *actual_word_size = 0; 765 } 766 767 return result; 768 } 769 770 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 771 assert(!is_init_completed(), "Expect to be called at JVM init time"); 772 assert(ranges != NULL, "MemRegion array NULL"); 773 assert(count != 0, "No MemRegions provided"); 774 MemRegion reserved = _hrm->reserved(); 775 HeapWord* prev_last_addr = NULL; 776 HeapRegion* prev_last_region = NULL; 777 size_t size_used = 0; 778 size_t uncommitted_regions = 0; 779 780 // For each Memregion, free the G1 regions that constitute it, and 781 // notify mark-sweep that the range is no longer to be considered 'archive.' 782 MutexLocker x(Heap_lock); 783 for (size_t i = 0; i < count; i++) { 784 HeapWord* start_address = ranges[i].start(); 785 HeapWord* last_address = ranges[i].last(); 786 787 assert(reserved.contains(start_address) && reserved.contains(last_address), 788 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 789 p2i(start_address), p2i(last_address)); 790 assert(start_address > prev_last_addr, 791 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 792 p2i(start_address), p2i(prev_last_addr)); 793 size_used += ranges[i].byte_size(); 794 prev_last_addr = last_address; 795 796 HeapRegion* start_region = _hrm->addr_to_region(start_address); 797 HeapRegion* last_region = _hrm->addr_to_region(last_address); 798 799 // Check for ranges that start in the same G1 region in which the previous 800 // range ended, and adjust the start address so we don't try to free 801 // the same region again. If the current range is entirely within that 802 // region, skip it. 803 if (start_region == prev_last_region) { 804 start_address = start_region->end(); 805 if (start_address > last_address) { 806 continue; 807 } 808 start_region = _hrm->addr_to_region(start_address); 809 } 810 prev_last_region = last_region; 811 812 // After verifying that each region was marked as an archive region by 813 // alloc_archive_regions, set it free and empty and uncommit it. 814 HeapRegion* curr_region = start_region; 815 while (curr_region != NULL) { 816 guarantee(curr_region->is_archive(), 817 "Expected archive region at index %u", curr_region->hrm_index()); 818 uint curr_index = curr_region->hrm_index(); 819 _archive_set.remove(curr_region); 820 curr_region->set_free(); 821 curr_region->set_top(curr_region->bottom()); 822 if (curr_region != last_region) { 823 curr_region = _hrm->next_region_in_heap(curr_region); 824 } else { 825 curr_region = NULL; 826 } 827 _hrm->shrink_at(curr_index, 1); 828 uncommitted_regions++; 829 } 830 831 // Notify mark-sweep that this is no longer an archive range. 832 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 833 } 834 835 if (uncommitted_regions != 0) { 836 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 837 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 838 } 839 decrease_used(size_used); 840 } 841 842 oop G1CollectedHeap::materialize_archived_object(oop obj) { 843 assert(obj != NULL, "archived obj is NULL"); 844 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 845 846 // Loading an archived object makes it strongly reachable. If it is 847 // loaded during concurrent marking, it must be enqueued to the SATB 848 // queue, shading the previously white object gray. 849 G1BarrierSet::enqueue(obj); 850 851 return obj; 852 } 853 854 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 855 ResourceMark rm; // For retrieving the thread names in log messages. 856 857 // The structure of this method has a lot of similarities to 858 // attempt_allocation_slow(). The reason these two were not merged 859 // into a single one is that such a method would require several "if 860 // allocation is not humongous do this, otherwise do that" 861 // conditional paths which would obscure its flow. In fact, an early 862 // version of this code did use a unified method which was harder to 863 // follow and, as a result, it had subtle bugs that were hard to 864 // track down. So keeping these two methods separate allows each to 865 // be more readable. It will be good to keep these two in sync as 866 // much as possible. 867 868 assert_heap_not_locked_and_not_at_safepoint(); 869 assert(is_humongous(word_size), "attempt_allocation_humongous() " 870 "should only be called for humongous allocations"); 871 872 // Humongous objects can exhaust the heap quickly, so we should check if we 873 // need to start a marking cycle at each humongous object allocation. We do 874 // the check before we do the actual allocation. The reason for doing it 875 // before the allocation is that we avoid having to keep track of the newly 876 // allocated memory while we do a GC. 877 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 878 word_size)) { 879 collect(GCCause::_g1_humongous_allocation); 880 } 881 882 // We will loop until a) we manage to successfully perform the 883 // allocation or b) we successfully schedule a collection which 884 // fails to perform the allocation. b) is the only case when we'll 885 // return NULL. 886 HeapWord* result = NULL; 887 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 888 bool should_try_gc; 889 uint gc_count_before; 890 891 892 { 893 MutexLocker x(Heap_lock); 894 895 // Given that humongous objects are not allocated in young 896 // regions, we'll first try to do the allocation without doing a 897 // collection hoping that there's enough space in the heap. 898 result = humongous_obj_allocate(word_size); 899 if (result != NULL) { 900 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 901 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 902 return result; 903 } 904 905 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 906 // the GCLocker initiated GC has been performed and then retry. This includes 907 // the case when the GC Locker is not active but has not been performed. 908 should_try_gc = !GCLocker::needs_gc(); 909 // Read the GC count while still holding the Heap_lock. 910 gc_count_before = total_collections(); 911 } 912 913 if (should_try_gc) { 914 bool succeeded; 915 result = do_collection_pause(word_size, gc_count_before, &succeeded, 916 GCCause::_g1_humongous_allocation); 917 if (result != NULL) { 918 assert(succeeded, "only way to get back a non-NULL result"); 919 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 920 Thread::current()->name(), p2i(result)); 921 return result; 922 } 923 924 if (succeeded) { 925 // We successfully scheduled a collection which failed to allocate. No 926 // point in trying to allocate further. We'll just return NULL. 927 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 928 SIZE_FORMAT " words", Thread::current()->name(), word_size); 929 return NULL; 930 } 931 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 932 Thread::current()->name(), word_size); 933 } else { 934 // Failed to schedule a collection. 935 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 936 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 937 SIZE_FORMAT " words", Thread::current()->name(), word_size); 938 return NULL; 939 } 940 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 941 // The GCLocker is either active or the GCLocker initiated 942 // GC has not yet been performed. Stall until it is and 943 // then retry the allocation. 944 GCLocker::stall_until_clear(); 945 gclocker_retry_count += 1; 946 } 947 948 949 // We can reach here if we were unsuccessful in scheduling a 950 // collection (because another thread beat us to it) or if we were 951 // stalled due to the GC locker. In either can we should retry the 952 // allocation attempt in case another thread successfully 953 // performed a collection and reclaimed enough space. 954 // Humongous object allocation always needs a lock, so we wait for the retry 955 // in the next iteration of the loop, unlike for the regular iteration case. 956 // Give a warning if we seem to be looping forever. 957 958 if ((QueuedAllocationWarningCount > 0) && 959 (try_count % QueuedAllocationWarningCount == 0)) { 960 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 961 Thread::current()->name(), try_count, word_size); 962 } 963 } 964 965 ShouldNotReachHere(); 966 return NULL; 967 } 968 969 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 970 bool expect_null_mutator_alloc_region) { 971 assert_at_safepoint_on_vm_thread(); 972 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 973 "the current alloc region was unexpectedly found to be non-NULL"); 974 975 if (!is_humongous(word_size)) { 976 return _allocator->attempt_allocation_locked(word_size); 977 } else { 978 HeapWord* result = humongous_obj_allocate(word_size); 979 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 980 collector_state()->set_initiate_conc_mark_if_possible(true); 981 } 982 return result; 983 } 984 985 ShouldNotReachHere(); 986 } 987 988 class PostCompactionPrinterClosure: public HeapRegionClosure { 989 private: 990 G1HRPrinter* _hr_printer; 991 public: 992 bool do_heap_region(HeapRegion* hr) { 993 assert(!hr->is_young(), "not expecting to find young regions"); 994 _hr_printer->post_compaction(hr); 995 return false; 996 } 997 998 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 999 : _hr_printer(hr_printer) { } 1000 }; 1001 1002 void G1CollectedHeap::print_hrm_post_compaction() { 1003 if (_hr_printer.is_active()) { 1004 PostCompactionPrinterClosure cl(hr_printer()); 1005 heap_region_iterate(&cl); 1006 } 1007 } 1008 1009 void G1CollectedHeap::abort_concurrent_cycle() { 1010 // If we start the compaction before the CM threads finish 1011 // scanning the root regions we might trip them over as we'll 1012 // be moving objects / updating references. So let's wait until 1013 // they are done. By telling them to abort, they should complete 1014 // early. 1015 _cm->root_regions()->abort(); 1016 _cm->root_regions()->wait_until_scan_finished(); 1017 1018 // Disable discovery and empty the discovered lists 1019 // for the CM ref processor. 1020 _ref_processor_cm->disable_discovery(); 1021 _ref_processor_cm->abandon_partial_discovery(); 1022 _ref_processor_cm->verify_no_references_recorded(); 1023 1024 // Abandon current iterations of concurrent marking and concurrent 1025 // refinement, if any are in progress. 1026 concurrent_mark()->concurrent_cycle_abort(); 1027 } 1028 1029 void G1CollectedHeap::prepare_heap_for_full_collection() { 1030 // Make sure we'll choose a new allocation region afterwards. 1031 _allocator->release_mutator_alloc_regions(); 1032 _allocator->abandon_gc_alloc_regions(); 1033 1034 // We may have added regions to the current incremental collection 1035 // set between the last GC or pause and now. We need to clear the 1036 // incremental collection set and then start rebuilding it afresh 1037 // after this full GC. 1038 abandon_collection_set(collection_set()); 1039 1040 tear_down_region_sets(false /* free_list_only */); 1041 1042 hrm()->prepare_for_full_collection_start(); 1043 } 1044 1045 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1046 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1047 assert_used_and_recalculate_used_equal(this); 1048 _verifier->verify_region_sets_optional(); 1049 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1050 _verifier->check_bitmaps("Full GC Start"); 1051 } 1052 1053 void G1CollectedHeap::prepare_heap_for_mutators() { 1054 hrm()->prepare_for_full_collection_end(); 1055 1056 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1057 ClassLoaderDataGraph::purge(); 1058 MetaspaceUtils::verify_metrics(); 1059 1060 // Prepare heap for normal collections. 1061 assert(num_free_regions() == 0, "we should not have added any free regions"); 1062 rebuild_region_sets(false /* free_list_only */); 1063 abort_refinement(); 1064 resize_heap_if_necessary(); 1065 1066 // Rebuild the strong code root lists for each region 1067 rebuild_strong_code_roots(); 1068 1069 // Purge code root memory 1070 purge_code_root_memory(); 1071 1072 // Start a new incremental collection set for the next pause 1073 start_new_collection_set(); 1074 1075 _allocator->init_mutator_alloc_regions(); 1076 1077 // Post collection state updates. 1078 MetaspaceGC::compute_new_size(); 1079 } 1080 1081 void G1CollectedHeap::abort_refinement() { 1082 if (_hot_card_cache->use_cache()) { 1083 _hot_card_cache->reset_hot_cache(); 1084 } 1085 1086 // Discard all remembered set updates. 1087 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1088 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1089 "DCQS should be empty"); 1090 } 1091 1092 void G1CollectedHeap::verify_after_full_collection() { 1093 _hrm->verify_optional(); 1094 _verifier->verify_region_sets_optional(); 1095 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1096 // Clear the previous marking bitmap, if needed for bitmap verification. 1097 // Note we cannot do this when we clear the next marking bitmap in 1098 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1099 // objects marked during a full GC against the previous bitmap. 1100 // But we need to clear it before calling check_bitmaps below since 1101 // the full GC has compacted objects and updated TAMS but not updated 1102 // the prev bitmap. 1103 if (G1VerifyBitmaps) { 1104 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1105 _cm->clear_prev_bitmap(workers()); 1106 } 1107 // This call implicitly verifies that the next bitmap is clear after Full GC. 1108 _verifier->check_bitmaps("Full GC End"); 1109 1110 // At this point there should be no regions in the 1111 // entire heap tagged as young. 1112 assert(check_young_list_empty(), "young list should be empty at this point"); 1113 1114 // Note: since we've just done a full GC, concurrent 1115 // marking is no longer active. Therefore we need not 1116 // re-enable reference discovery for the CM ref processor. 1117 // That will be done at the start of the next marking cycle. 1118 // We also know that the STW processor should no longer 1119 // discover any new references. 1120 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1121 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1122 _ref_processor_stw->verify_no_references_recorded(); 1123 _ref_processor_cm->verify_no_references_recorded(); 1124 } 1125 1126 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1127 // Post collection logging. 1128 // We should do this after we potentially resize the heap so 1129 // that all the COMMIT / UNCOMMIT events are generated before 1130 // the compaction events. 1131 print_hrm_post_compaction(); 1132 heap_transition->print(); 1133 print_heap_after_gc(); 1134 print_heap_regions(); 1135 #ifdef TRACESPINNING 1136 ParallelTaskTerminator::print_termination_counts(); 1137 #endif 1138 } 1139 1140 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1141 bool clear_all_soft_refs) { 1142 assert_at_safepoint_on_vm_thread(); 1143 1144 if (GCLocker::check_active_before_gc()) { 1145 // Full GC was not completed. 1146 return false; 1147 } 1148 1149 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1150 soft_ref_policy()->should_clear_all_soft_refs(); 1151 1152 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1153 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1154 1155 collector.prepare_collection(); 1156 collector.collect(); 1157 collector.complete_collection(); 1158 1159 // Full collection was successfully completed. 1160 return true; 1161 } 1162 1163 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1164 // Currently, there is no facility in the do_full_collection(bool) API to notify 1165 // the caller that the collection did not succeed (e.g., because it was locked 1166 // out by the GC locker). So, right now, we'll ignore the return value. 1167 bool dummy = do_full_collection(true, /* explicit_gc */ 1168 clear_all_soft_refs); 1169 } 1170 1171 void G1CollectedHeap::resize_heap_if_necessary() { 1172 assert_at_safepoint_on_vm_thread(); 1173 1174 // Capacity, free and used after the GC counted as full regions to 1175 // include the waste in the following calculations. 1176 const size_t capacity_after_gc = capacity(); 1177 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1178 1179 // This is enforced in arguments.cpp. 1180 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1181 "otherwise the code below doesn't make sense"); 1182 1183 // We don't have floating point command-line arguments 1184 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1185 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1186 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1187 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1188 1189 // We have to be careful here as these two calculations can overflow 1190 // 32-bit size_t's. 1191 double used_after_gc_d = (double) used_after_gc; 1192 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1193 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1194 1195 // Let's make sure that they are both under the max heap size, which 1196 // by default will make them fit into a size_t. 1197 double desired_capacity_upper_bound = (double) MaxHeapSize; 1198 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1199 desired_capacity_upper_bound); 1200 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1201 desired_capacity_upper_bound); 1202 1203 // We can now safely turn them into size_t's. 1204 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1205 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1206 1207 // This assert only makes sense here, before we adjust them 1208 // with respect to the min and max heap size. 1209 assert(minimum_desired_capacity <= maximum_desired_capacity, 1210 "minimum_desired_capacity = " SIZE_FORMAT ", " 1211 "maximum_desired_capacity = " SIZE_FORMAT, 1212 minimum_desired_capacity, maximum_desired_capacity); 1213 1214 // Should not be greater than the heap max size. No need to adjust 1215 // it with respect to the heap min size as it's a lower bound (i.e., 1216 // we'll try to make the capacity larger than it, not smaller). 1217 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1218 // Should not be less than the heap min size. No need to adjust it 1219 // with respect to the heap max size as it's an upper bound (i.e., 1220 // we'll try to make the capacity smaller than it, not greater). 1221 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1222 1223 if (capacity_after_gc < minimum_desired_capacity) { 1224 // Don't expand unless it's significant 1225 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1226 1227 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1228 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1229 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1230 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1231 1232 expand(expand_bytes, _workers); 1233 1234 // No expansion, now see if we want to shrink 1235 } else if (capacity_after_gc > maximum_desired_capacity) { 1236 // Capacity too large, compute shrinking size 1237 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1238 1239 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1240 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1241 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1242 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1243 1244 shrink(shrink_bytes); 1245 } 1246 } 1247 1248 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1249 bool do_gc, 1250 bool clear_all_soft_refs, 1251 bool expect_null_mutator_alloc_region, 1252 bool* gc_succeeded) { 1253 *gc_succeeded = true; 1254 // Let's attempt the allocation first. 1255 HeapWord* result = 1256 attempt_allocation_at_safepoint(word_size, 1257 expect_null_mutator_alloc_region); 1258 if (result != NULL) { 1259 return result; 1260 } 1261 1262 // In a G1 heap, we're supposed to keep allocation from failing by 1263 // incremental pauses. Therefore, at least for now, we'll favor 1264 // expansion over collection. (This might change in the future if we can 1265 // do something smarter than full collection to satisfy a failed alloc.) 1266 result = expand_and_allocate(word_size); 1267 if (result != NULL) { 1268 return result; 1269 } 1270 1271 if (do_gc) { 1272 // Expansion didn't work, we'll try to do a Full GC. 1273 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1274 clear_all_soft_refs); 1275 } 1276 1277 return NULL; 1278 } 1279 1280 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1281 bool* succeeded) { 1282 assert_at_safepoint_on_vm_thread(); 1283 1284 // Attempts to allocate followed by Full GC. 1285 HeapWord* result = 1286 satisfy_failed_allocation_helper(word_size, 1287 true, /* do_gc */ 1288 false, /* clear_all_soft_refs */ 1289 false, /* expect_null_mutator_alloc_region */ 1290 succeeded); 1291 1292 if (result != NULL || !*succeeded) { 1293 return result; 1294 } 1295 1296 // Attempts to allocate followed by Full GC that will collect all soft references. 1297 result = satisfy_failed_allocation_helper(word_size, 1298 true, /* do_gc */ 1299 true, /* clear_all_soft_refs */ 1300 true, /* expect_null_mutator_alloc_region */ 1301 succeeded); 1302 1303 if (result != NULL || !*succeeded) { 1304 return result; 1305 } 1306 1307 // Attempts to allocate, no GC 1308 result = satisfy_failed_allocation_helper(word_size, 1309 false, /* do_gc */ 1310 false, /* clear_all_soft_refs */ 1311 true, /* expect_null_mutator_alloc_region */ 1312 succeeded); 1313 1314 if (result != NULL) { 1315 return result; 1316 } 1317 1318 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1319 "Flag should have been handled and cleared prior to this point"); 1320 1321 // What else? We might try synchronous finalization later. If the total 1322 // space available is large enough for the allocation, then a more 1323 // complete compaction phase than we've tried so far might be 1324 // appropriate. 1325 return NULL; 1326 } 1327 1328 // Attempting to expand the heap sufficiently 1329 // to support an allocation of the given "word_size". If 1330 // successful, perform the allocation and return the address of the 1331 // allocated block, or else "NULL". 1332 1333 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1334 assert_at_safepoint_on_vm_thread(); 1335 1336 _verifier->verify_region_sets_optional(); 1337 1338 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1339 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1340 word_size * HeapWordSize); 1341 1342 1343 if (expand(expand_bytes, _workers)) { 1344 _hrm->verify_optional(); 1345 _verifier->verify_region_sets_optional(); 1346 return attempt_allocation_at_safepoint(word_size, 1347 false /* expect_null_mutator_alloc_region */); 1348 } 1349 return NULL; 1350 } 1351 1352 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1353 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1354 aligned_expand_bytes = align_up(aligned_expand_bytes, 1355 HeapRegion::GrainBytes); 1356 1357 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1358 expand_bytes, aligned_expand_bytes); 1359 1360 if (is_maximal_no_gc()) { 1361 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1362 return false; 1363 } 1364 1365 double expand_heap_start_time_sec = os::elapsedTime(); 1366 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1367 assert(regions_to_expand > 0, "Must expand by at least one region"); 1368 1369 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1370 if (expand_time_ms != NULL) { 1371 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1372 } 1373 1374 if (expanded_by > 0) { 1375 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1376 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1377 policy()->record_new_heap_size(num_regions()); 1378 } else { 1379 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1380 1381 // The expansion of the virtual storage space was unsuccessful. 1382 // Let's see if it was because we ran out of swap. 1383 if (G1ExitOnExpansionFailure && 1384 _hrm->available() >= regions_to_expand) { 1385 // We had head room... 1386 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1387 } 1388 } 1389 return regions_to_expand > 0; 1390 } 1391 1392 bool G1CollectedHeap::expand_single_region(uint node_index) { 1393 log_debug(gc, ergo, heap)("Expand the heap by a single region"); 1394 1395 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1396 1397 if (expanded_by == 0) { 1398 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1399 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1400 return false; 1401 } 1402 1403 policy()->record_new_heap_size(num_regions()); 1404 return true; 1405 } 1406 1407 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1408 size_t aligned_shrink_bytes = 1409 ReservedSpace::page_align_size_down(shrink_bytes); 1410 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1411 HeapRegion::GrainBytes); 1412 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1413 1414 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1415 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1416 1417 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", 1418 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1419 if (num_regions_removed > 0) { 1420 policy()->record_new_heap_size(num_regions()); 1421 } else { 1422 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1423 } 1424 } 1425 1426 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1427 _verifier->verify_region_sets_optional(); 1428 1429 // We should only reach here at the end of a Full GC or during Remark which 1430 // means we should not not be holding to any GC alloc regions. The method 1431 // below will make sure of that and do any remaining clean up. 1432 _allocator->abandon_gc_alloc_regions(); 1433 1434 // Instead of tearing down / rebuilding the free lists here, we 1435 // could instead use the remove_all_pending() method on free_list to 1436 // remove only the ones that we need to remove. 1437 tear_down_region_sets(true /* free_list_only */); 1438 shrink_helper(shrink_bytes); 1439 rebuild_region_sets(true /* free_list_only */); 1440 1441 _hrm->verify_optional(); 1442 _verifier->verify_region_sets_optional(); 1443 } 1444 1445 class OldRegionSetChecker : public HeapRegionSetChecker { 1446 public: 1447 void check_mt_safety() { 1448 // Master Old Set MT safety protocol: 1449 // (a) If we're at a safepoint, operations on the master old set 1450 // should be invoked: 1451 // - by the VM thread (which will serialize them), or 1452 // - by the GC workers while holding the FreeList_lock, if we're 1453 // at a safepoint for an evacuation pause (this lock is taken 1454 // anyway when an GC alloc region is retired so that a new one 1455 // is allocated from the free list), or 1456 // - by the GC workers while holding the OldSets_lock, if we're at a 1457 // safepoint for a cleanup pause. 1458 // (b) If we're not at a safepoint, operations on the master old set 1459 // should be invoked while holding the Heap_lock. 1460 1461 if (SafepointSynchronize::is_at_safepoint()) { 1462 guarantee(Thread::current()->is_VM_thread() || 1463 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1464 "master old set MT safety protocol at a safepoint"); 1465 } else { 1466 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1467 } 1468 } 1469 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1470 const char* get_description() { return "Old Regions"; } 1471 }; 1472 1473 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1474 public: 1475 void check_mt_safety() { 1476 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1477 "May only change archive regions during initialization or safepoint."); 1478 } 1479 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1480 const char* get_description() { return "Archive Regions"; } 1481 }; 1482 1483 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1484 public: 1485 void check_mt_safety() { 1486 // Humongous Set MT safety protocol: 1487 // (a) If we're at a safepoint, operations on the master humongous 1488 // set should be invoked by either the VM thread (which will 1489 // serialize them) or by the GC workers while holding the 1490 // OldSets_lock. 1491 // (b) If we're not at a safepoint, operations on the master 1492 // humongous set should be invoked while holding the Heap_lock. 1493 1494 if (SafepointSynchronize::is_at_safepoint()) { 1495 guarantee(Thread::current()->is_VM_thread() || 1496 OldSets_lock->owned_by_self(), 1497 "master humongous set MT safety protocol at a safepoint"); 1498 } else { 1499 guarantee(Heap_lock->owned_by_self(), 1500 "master humongous set MT safety protocol outside a safepoint"); 1501 } 1502 } 1503 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1504 const char* get_description() { return "Humongous Regions"; } 1505 }; 1506 1507 G1CollectedHeap::G1CollectedHeap() : 1508 CollectedHeap(), 1509 _young_gen_sampling_thread(NULL), 1510 _workers(NULL), 1511 _card_table(NULL), 1512 _soft_ref_policy(), 1513 _old_set("Old Region Set", new OldRegionSetChecker()), 1514 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1515 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1516 _bot(NULL), 1517 _listener(), 1518 _mem_node_mgr(G1MemoryNodeManager::create()), 1519 _hrm(NULL), 1520 _allocator(NULL), 1521 _verifier(NULL), 1522 _summary_bytes_used(0), 1523 _archive_allocator(NULL), 1524 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1525 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1526 _expand_heap_after_alloc_failure(true), 1527 _g1mm(NULL), 1528 _humongous_reclaim_candidates(), 1529 _has_humongous_reclaim_candidates(false), 1530 _hr_printer(), 1531 _collector_state(), 1532 _old_marking_cycles_started(0), 1533 _old_marking_cycles_completed(0), 1534 _eden(), 1535 _survivor(), 1536 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1537 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1538 _policy(G1Policy::create_policy(_gc_timer_stw)), 1539 _heap_sizing_policy(NULL), 1540 _collection_set(this, _policy), 1541 _hot_card_cache(NULL), 1542 _rem_set(NULL), 1543 _cm(NULL), 1544 _cm_thread(NULL), 1545 _cr(NULL), 1546 _task_queues(NULL), 1547 _evacuation_failed(false), 1548 _evacuation_failed_info_array(NULL), 1549 _preserved_marks_set(true /* in_c_heap */), 1550 #ifndef PRODUCT 1551 _evacuation_failure_alot_for_current_gc(false), 1552 _evacuation_failure_alot_gc_number(0), 1553 _evacuation_failure_alot_count(0), 1554 #endif 1555 _ref_processor_stw(NULL), 1556 _is_alive_closure_stw(this), 1557 _is_subject_to_discovery_stw(this), 1558 _ref_processor_cm(NULL), 1559 _is_alive_closure_cm(this), 1560 _is_subject_to_discovery_cm(this), 1561 _region_attr() { 1562 1563 _verifier = new G1HeapVerifier(this); 1564 1565 _allocator = new G1Allocator(this); 1566 1567 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1568 1569 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1570 1571 // Override the default _filler_array_max_size so that no humongous filler 1572 // objects are created. 1573 _filler_array_max_size = _humongous_object_threshold_in_words; 1574 1575 uint n_queues = ParallelGCThreads; 1576 _task_queues = new RefToScanQueueSet(n_queues); 1577 1578 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1579 1580 for (uint i = 0; i < n_queues; i++) { 1581 RefToScanQueue* q = new RefToScanQueue(); 1582 q->initialize(); 1583 _task_queues->register_queue(i, q); 1584 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1585 } 1586 1587 // Initialize the G1EvacuationFailureALot counters and flags. 1588 NOT_PRODUCT(reset_evacuation_should_fail();) 1589 _gc_tracer_stw->initialize(); 1590 1591 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1592 } 1593 1594 static size_t actual_reserved_page_size(ReservedSpace rs) { 1595 size_t page_size = os::vm_page_size(); 1596 if (UseLargePages) { 1597 // There are two ways to manage large page memory. 1598 // 1. OS supports committing large page memory. 1599 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1600 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1601 // we reserved memory without large page. 1602 if (os::can_commit_large_page_memory() || rs.special()) { 1603 // An alignment at ReservedSpace comes from preferred page size or 1604 // heap alignment, and if the alignment came from heap alignment, it could be 1605 // larger than large pages size. So need to cap with the large page size. 1606 page_size = MIN2(rs.alignment(), os::large_page_size()); 1607 } 1608 } 1609 1610 return page_size; 1611 } 1612 1613 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1614 size_t size, 1615 size_t translation_factor) { 1616 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1617 // Allocate a new reserved space, preferring to use large pages. 1618 ReservedSpace rs(size, preferred_page_size); 1619 size_t page_size = actual_reserved_page_size(rs); 1620 G1RegionToSpaceMapper* result = 1621 G1RegionToSpaceMapper::create_mapper(rs, 1622 size, 1623 page_size, 1624 HeapRegion::GrainBytes, 1625 translation_factor, 1626 mtGC); 1627 1628 os::trace_page_sizes_for_requested_size(description, 1629 size, 1630 preferred_page_size, 1631 page_size, 1632 rs.base(), 1633 rs.size()); 1634 1635 return result; 1636 } 1637 1638 jint G1CollectedHeap::initialize_concurrent_refinement() { 1639 jint ecode = JNI_OK; 1640 _cr = G1ConcurrentRefine::create(&ecode); 1641 return ecode; 1642 } 1643 1644 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1645 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1646 if (_young_gen_sampling_thread->osthread() == NULL) { 1647 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1648 return JNI_ENOMEM; 1649 } 1650 return JNI_OK; 1651 } 1652 1653 jint G1CollectedHeap::initialize() { 1654 os::enable_vtime(); 1655 1656 // Necessary to satisfy locking discipline assertions. 1657 1658 MutexLocker x(Heap_lock); 1659 1660 // While there are no constraints in the GC code that HeapWordSize 1661 // be any particular value, there are multiple other areas in the 1662 // system which believe this to be true (e.g. oop->object_size in some 1663 // cases incorrectly returns the size in wordSize units rather than 1664 // HeapWordSize). 1665 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1666 1667 size_t init_byte_size = InitialHeapSize; 1668 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1669 1670 // Ensure that the sizes are properly aligned. 1671 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1672 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1673 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1674 1675 // Reserve the maximum. 1676 1677 // When compressed oops are enabled, the preferred heap base 1678 // is calculated by subtracting the requested size from the 1679 // 32Gb boundary and using the result as the base address for 1680 // heap reservation. If the requested size is not aligned to 1681 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1682 // into the ReservedHeapSpace constructor) then the actual 1683 // base of the reserved heap may end up differing from the 1684 // address that was requested (i.e. the preferred heap base). 1685 // If this happens then we could end up using a non-optimal 1686 // compressed oops mode. 1687 1688 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1689 HeapAlignment); 1690 1691 initialize_reserved_region(heap_rs); 1692 1693 // Create the barrier set for the entire reserved region. 1694 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1695 ct->initialize(); 1696 G1BarrierSet* bs = new G1BarrierSet(ct); 1697 bs->initialize(); 1698 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1699 BarrierSet::set_barrier_set(bs); 1700 _card_table = ct; 1701 1702 { 1703 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1704 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1705 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1706 } 1707 1708 // Create the hot card cache. 1709 _hot_card_cache = new G1HotCardCache(this); 1710 1711 // Carve out the G1 part of the heap. 1712 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1713 size_t page_size = actual_reserved_page_size(heap_rs); 1714 G1RegionToSpaceMapper* heap_storage = 1715 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1716 g1_rs.size(), 1717 page_size, 1718 HeapRegion::GrainBytes, 1719 1, 1720 mtJavaHeap); 1721 if(heap_storage == NULL) { 1722 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1723 return JNI_ERR; 1724 } 1725 1726 os::trace_page_sizes("Heap", 1727 MinHeapSize, 1728 reserved_byte_size, 1729 page_size, 1730 heap_rs.base(), 1731 heap_rs.size()); 1732 heap_storage->set_mapping_changed_listener(&_listener); 1733 1734 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1735 G1RegionToSpaceMapper* bot_storage = 1736 create_aux_memory_mapper("Block Offset Table", 1737 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1738 G1BlockOffsetTable::heap_map_factor()); 1739 1740 G1RegionToSpaceMapper* cardtable_storage = 1741 create_aux_memory_mapper("Card Table", 1742 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1743 G1CardTable::heap_map_factor()); 1744 1745 G1RegionToSpaceMapper* card_counts_storage = 1746 create_aux_memory_mapper("Card Counts Table", 1747 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1748 G1CardCounts::heap_map_factor()); 1749 1750 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1751 G1RegionToSpaceMapper* prev_bitmap_storage = 1752 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1753 G1RegionToSpaceMapper* next_bitmap_storage = 1754 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1755 1756 _hrm = HeapRegionManager::create_manager(this); 1757 1758 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1759 _card_table->initialize(cardtable_storage); 1760 1761 // Do later initialization work for concurrent refinement. 1762 _hot_card_cache->initialize(card_counts_storage); 1763 1764 // 6843694 - ensure that the maximum region index can fit 1765 // in the remembered set structures. 1766 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1767 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1768 1769 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1770 // start within the first card. 1771 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1772 // Also create a G1 rem set. 1773 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1774 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1775 1776 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1777 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1778 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1779 "too many cards per region"); 1780 1781 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1782 1783 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1784 1785 { 1786 HeapWord* start = _hrm->reserved().start(); 1787 HeapWord* end = _hrm->reserved().end(); 1788 size_t granularity = HeapRegion::GrainBytes; 1789 1790 _region_attr.initialize(start, end, granularity); 1791 _humongous_reclaim_candidates.initialize(start, end, granularity); 1792 } 1793 1794 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1795 true /* are_GC_task_threads */, 1796 false /* are_ConcurrentGC_threads */); 1797 if (_workers == NULL) { 1798 return JNI_ENOMEM; 1799 } 1800 _workers->initialize_workers(); 1801 1802 _mem_node_mgr->set_page_size(page_size); 1803 1804 // Create the G1ConcurrentMark data structure and thread. 1805 // (Must do this late, so that "max_regions" is defined.) 1806 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1807 if (_cm == NULL || !_cm->completed_initialization()) { 1808 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1809 return JNI_ENOMEM; 1810 } 1811 _cm_thread = _cm->cm_thread(); 1812 1813 // Now expand into the initial heap size. 1814 if (!expand(init_byte_size, _workers)) { 1815 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1816 return JNI_ENOMEM; 1817 } 1818 1819 // Perform any initialization actions delegated to the policy. 1820 policy()->init(this, &_collection_set); 1821 1822 jint ecode = initialize_concurrent_refinement(); 1823 if (ecode != JNI_OK) { 1824 return ecode; 1825 } 1826 1827 ecode = initialize_young_gen_sampling_thread(); 1828 if (ecode != JNI_OK) { 1829 return ecode; 1830 } 1831 1832 { 1833 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1834 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1835 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1836 } 1837 1838 // Here we allocate the dummy HeapRegion that is required by the 1839 // G1AllocRegion class. 1840 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1841 1842 // We'll re-use the same region whether the alloc region will 1843 // require BOT updates or not and, if it doesn't, then a non-young 1844 // region will complain that it cannot support allocations without 1845 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1846 dummy_region->set_eden(); 1847 // Make sure it's full. 1848 dummy_region->set_top(dummy_region->end()); 1849 G1AllocRegion::setup(this, dummy_region); 1850 1851 _allocator->init_mutator_alloc_regions(); 1852 1853 // Do create of the monitoring and management support so that 1854 // values in the heap have been properly initialized. 1855 _g1mm = new G1MonitoringSupport(this); 1856 1857 G1StringDedup::initialize(); 1858 1859 _preserved_marks_set.init(ParallelGCThreads); 1860 1861 _collection_set.initialize(max_regions()); 1862 1863 return JNI_OK; 1864 } 1865 1866 void G1CollectedHeap::stop() { 1867 // Stop all concurrent threads. We do this to make sure these threads 1868 // do not continue to execute and access resources (e.g. logging) 1869 // that are destroyed during shutdown. 1870 _cr->stop(); 1871 _young_gen_sampling_thread->stop(); 1872 _cm_thread->stop(); 1873 if (G1StringDedup::is_enabled()) { 1874 G1StringDedup::stop(); 1875 } 1876 } 1877 1878 void G1CollectedHeap::safepoint_synchronize_begin() { 1879 SuspendibleThreadSet::synchronize(); 1880 } 1881 1882 void G1CollectedHeap::safepoint_synchronize_end() { 1883 SuspendibleThreadSet::desynchronize(); 1884 } 1885 1886 void G1CollectedHeap::post_initialize() { 1887 CollectedHeap::post_initialize(); 1888 ref_processing_init(); 1889 } 1890 1891 void G1CollectedHeap::ref_processing_init() { 1892 // Reference processing in G1 currently works as follows: 1893 // 1894 // * There are two reference processor instances. One is 1895 // used to record and process discovered references 1896 // during concurrent marking; the other is used to 1897 // record and process references during STW pauses 1898 // (both full and incremental). 1899 // * Both ref processors need to 'span' the entire heap as 1900 // the regions in the collection set may be dotted around. 1901 // 1902 // * For the concurrent marking ref processor: 1903 // * Reference discovery is enabled at initial marking. 1904 // * Reference discovery is disabled and the discovered 1905 // references processed etc during remarking. 1906 // * Reference discovery is MT (see below). 1907 // * Reference discovery requires a barrier (see below). 1908 // * Reference processing may or may not be MT 1909 // (depending on the value of ParallelRefProcEnabled 1910 // and ParallelGCThreads). 1911 // * A full GC disables reference discovery by the CM 1912 // ref processor and abandons any entries on it's 1913 // discovered lists. 1914 // 1915 // * For the STW processor: 1916 // * Non MT discovery is enabled at the start of a full GC. 1917 // * Processing and enqueueing during a full GC is non-MT. 1918 // * During a full GC, references are processed after marking. 1919 // 1920 // * Discovery (may or may not be MT) is enabled at the start 1921 // of an incremental evacuation pause. 1922 // * References are processed near the end of a STW evacuation pause. 1923 // * For both types of GC: 1924 // * Discovery is atomic - i.e. not concurrent. 1925 // * Reference discovery will not need a barrier. 1926 1927 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1928 1929 // Concurrent Mark ref processor 1930 _ref_processor_cm = 1931 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1932 mt_processing, // mt processing 1933 ParallelGCThreads, // degree of mt processing 1934 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1935 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1936 false, // Reference discovery is not atomic 1937 &_is_alive_closure_cm, // is alive closure 1938 true); // allow changes to number of processing threads 1939 1940 // STW ref processor 1941 _ref_processor_stw = 1942 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1943 mt_processing, // mt processing 1944 ParallelGCThreads, // degree of mt processing 1945 (ParallelGCThreads > 1), // mt discovery 1946 ParallelGCThreads, // degree of mt discovery 1947 true, // Reference discovery is atomic 1948 &_is_alive_closure_stw, // is alive closure 1949 true); // allow changes to number of processing threads 1950 } 1951 1952 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1953 return &_soft_ref_policy; 1954 } 1955 1956 size_t G1CollectedHeap::capacity() const { 1957 return _hrm->length() * HeapRegion::GrainBytes; 1958 } 1959 1960 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1961 return _hrm->total_free_bytes(); 1962 } 1963 1964 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1965 _hot_card_cache->drain(cl, worker_id); 1966 } 1967 1968 // Computes the sum of the storage used by the various regions. 1969 size_t G1CollectedHeap::used() const { 1970 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1971 if (_archive_allocator != NULL) { 1972 result += _archive_allocator->used(); 1973 } 1974 return result; 1975 } 1976 1977 size_t G1CollectedHeap::used_unlocked() const { 1978 return _summary_bytes_used; 1979 } 1980 1981 class SumUsedClosure: public HeapRegionClosure { 1982 size_t _used; 1983 public: 1984 SumUsedClosure() : _used(0) {} 1985 bool do_heap_region(HeapRegion* r) { 1986 _used += r->used(); 1987 return false; 1988 } 1989 size_t result() { return _used; } 1990 }; 1991 1992 size_t G1CollectedHeap::recalculate_used() const { 1993 SumUsedClosure blk; 1994 heap_region_iterate(&blk); 1995 return blk.result(); 1996 } 1997 1998 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1999 switch (cause) { 2000 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2001 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2002 case GCCause::_wb_conc_mark: return true; 2003 default : return false; 2004 } 2005 } 2006 2007 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2008 switch (cause) { 2009 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2010 case GCCause::_g1_humongous_allocation: return true; 2011 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2012 default: return is_user_requested_concurrent_full_gc(cause); 2013 } 2014 } 2015 2016 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2017 if(policy()->force_upgrade_to_full()) { 2018 return true; 2019 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2020 return false; 2021 } else if (has_regions_left_for_allocation()) { 2022 return false; 2023 } else { 2024 return true; 2025 } 2026 } 2027 2028 #ifndef PRODUCT 2029 void G1CollectedHeap::allocate_dummy_regions() { 2030 // Let's fill up most of the region 2031 size_t word_size = HeapRegion::GrainWords - 1024; 2032 // And as a result the region we'll allocate will be humongous. 2033 guarantee(is_humongous(word_size), "sanity"); 2034 2035 // _filler_array_max_size is set to humongous object threshold 2036 // but temporarily change it to use CollectedHeap::fill_with_object(). 2037 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2038 2039 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2040 // Let's use the existing mechanism for the allocation 2041 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2042 if (dummy_obj != NULL) { 2043 MemRegion mr(dummy_obj, word_size); 2044 CollectedHeap::fill_with_object(mr); 2045 } else { 2046 // If we can't allocate once, we probably cannot allocate 2047 // again. Let's get out of the loop. 2048 break; 2049 } 2050 } 2051 } 2052 #endif // !PRODUCT 2053 2054 void G1CollectedHeap::increment_old_marking_cycles_started() { 2055 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2056 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2057 "Wrong marking cycle count (started: %d, completed: %d)", 2058 _old_marking_cycles_started, _old_marking_cycles_completed); 2059 2060 _old_marking_cycles_started++; 2061 } 2062 2063 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2064 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2065 2066 // We assume that if concurrent == true, then the caller is a 2067 // concurrent thread that was joined the Suspendible Thread 2068 // Set. If there's ever a cheap way to check this, we should add an 2069 // assert here. 2070 2071 // Given that this method is called at the end of a Full GC or of a 2072 // concurrent cycle, and those can be nested (i.e., a Full GC can 2073 // interrupt a concurrent cycle), the number of full collections 2074 // completed should be either one (in the case where there was no 2075 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2076 // behind the number of full collections started. 2077 2078 // This is the case for the inner caller, i.e. a Full GC. 2079 assert(concurrent || 2080 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2081 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2082 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2083 "is inconsistent with _old_marking_cycles_completed = %u", 2084 _old_marking_cycles_started, _old_marking_cycles_completed); 2085 2086 // This is the case for the outer caller, i.e. the concurrent cycle. 2087 assert(!concurrent || 2088 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2089 "for outer caller (concurrent cycle): " 2090 "_old_marking_cycles_started = %u " 2091 "is inconsistent with _old_marking_cycles_completed = %u", 2092 _old_marking_cycles_started, _old_marking_cycles_completed); 2093 2094 _old_marking_cycles_completed += 1; 2095 2096 // We need to clear the "in_progress" flag in the CM thread before 2097 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2098 // is set) so that if a waiter requests another System.gc() it doesn't 2099 // incorrectly see that a marking cycle is still in progress. 2100 if (concurrent) { 2101 _cm_thread->set_idle(); 2102 } 2103 2104 // This notify_all() will ensure that a thread that called 2105 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2106 // and it's waiting for a full GC to finish will be woken up. It is 2107 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2108 FullGCCount_lock->notify_all(); 2109 } 2110 2111 void G1CollectedHeap::collect(GCCause::Cause cause) { 2112 try_collect(cause, true); 2113 } 2114 2115 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2116 assert_heap_not_locked(); 2117 2118 bool gc_succeeded; 2119 bool should_retry_gc; 2120 2121 do { 2122 should_retry_gc = false; 2123 2124 uint gc_count_before; 2125 uint old_marking_count_before; 2126 uint full_gc_count_before; 2127 2128 { 2129 MutexLocker ml(Heap_lock); 2130 2131 // Read the GC count while holding the Heap_lock 2132 gc_count_before = total_collections(); 2133 full_gc_count_before = total_full_collections(); 2134 old_marking_count_before = _old_marking_cycles_started; 2135 } 2136 2137 if (should_do_concurrent_full_gc(cause)) { 2138 // Schedule an initial-mark evacuation pause that will start a 2139 // concurrent cycle. We're setting word_size to 0 which means that 2140 // we are not requesting a post-GC allocation. 2141 VM_G1CollectForAllocation op(0, /* word_size */ 2142 gc_count_before, 2143 cause, 2144 true, /* should_initiate_conc_mark */ 2145 policy()->max_pause_time_ms()); 2146 VMThread::execute(&op); 2147 gc_succeeded = op.gc_succeeded(); 2148 if (!gc_succeeded && retry_on_gc_failure) { 2149 if (old_marking_count_before == _old_marking_cycles_started) { 2150 should_retry_gc = op.should_retry_gc(); 2151 } else { 2152 // A Full GC happened while we were trying to schedule the 2153 // concurrent cycle. No point in starting a new cycle given 2154 // that the whole heap was collected anyway. 2155 } 2156 2157 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2158 GCLocker::stall_until_clear(); 2159 } 2160 } 2161 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2162 // Return false to be consistent with VMOp failure due to 2163 // another collection slipping in after our gc_count but before 2164 // our request is processed. _gc_locker collections upgraded by 2165 // GCLockerInvokesConcurrent are handled above and never discarded. 2166 return false; 2167 } else { 2168 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2169 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2170 2171 // Schedule a standard evacuation pause. We're setting word_size 2172 // to 0 which means that we are not requesting a post-GC allocation. 2173 VM_G1CollectForAllocation op(0, /* word_size */ 2174 gc_count_before, 2175 cause, 2176 false, /* should_initiate_conc_mark */ 2177 policy()->max_pause_time_ms()); 2178 VMThread::execute(&op); 2179 gc_succeeded = op.gc_succeeded(); 2180 } else { 2181 // Schedule a Full GC. 2182 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2183 VMThread::execute(&op); 2184 gc_succeeded = op.gc_succeeded(); 2185 } 2186 } 2187 } while (should_retry_gc); 2188 return gc_succeeded; 2189 } 2190 2191 bool G1CollectedHeap::is_in(const void* p) const { 2192 if (_hrm->reserved().contains(p)) { 2193 // Given that we know that p is in the reserved space, 2194 // heap_region_containing() should successfully 2195 // return the containing region. 2196 HeapRegion* hr = heap_region_containing(p); 2197 return hr->is_in(p); 2198 } else { 2199 return false; 2200 } 2201 } 2202 2203 #ifdef ASSERT 2204 bool G1CollectedHeap::is_in_exact(const void* p) const { 2205 bool contains = reserved_region().contains(p); 2206 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2207 if (contains && available) { 2208 return true; 2209 } else { 2210 return false; 2211 } 2212 } 2213 #endif 2214 2215 // Iteration functions. 2216 2217 // Iterates an ObjectClosure over all objects within a HeapRegion. 2218 2219 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2220 ObjectClosure* _cl; 2221 public: 2222 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2223 bool do_heap_region(HeapRegion* r) { 2224 if (!r->is_continues_humongous()) { 2225 r->object_iterate(_cl); 2226 } 2227 return false; 2228 } 2229 }; 2230 2231 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2232 IterateObjectClosureRegionClosure blk(cl); 2233 heap_region_iterate(&blk); 2234 } 2235 2236 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2237 _hrm->iterate(cl); 2238 } 2239 2240 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2241 HeapRegionClaimer *hrclaimer, 2242 uint worker_id) const { 2243 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2244 } 2245 2246 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2247 HeapRegionClaimer *hrclaimer) const { 2248 _hrm->par_iterate(cl, hrclaimer, 0); 2249 } 2250 2251 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2252 _collection_set.iterate(cl); 2253 } 2254 2255 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2256 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2257 } 2258 2259 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2260 HeapRegion* hr = heap_region_containing(addr); 2261 return hr->block_start(addr); 2262 } 2263 2264 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2265 HeapRegion* hr = heap_region_containing(addr); 2266 return hr->block_is_obj(addr); 2267 } 2268 2269 bool G1CollectedHeap::supports_tlab_allocation() const { 2270 return true; 2271 } 2272 2273 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2274 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2275 } 2276 2277 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2278 return _eden.length() * HeapRegion::GrainBytes; 2279 } 2280 2281 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2282 // must be equal to the humongous object limit. 2283 size_t G1CollectedHeap::max_tlab_size() const { 2284 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2285 } 2286 2287 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2288 return _allocator->unsafe_max_tlab_alloc(); 2289 } 2290 2291 size_t G1CollectedHeap::max_capacity() const { 2292 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2293 } 2294 2295 size_t G1CollectedHeap::max_reserved_capacity() const { 2296 return _hrm->max_length() * HeapRegion::GrainBytes; 2297 } 2298 2299 jlong G1CollectedHeap::millis_since_last_gc() { 2300 // See the notes in GenCollectedHeap::millis_since_last_gc() 2301 // for more information about the implementation. 2302 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2303 _policy->collection_pause_end_millis(); 2304 if (ret_val < 0) { 2305 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2306 ". returning zero instead.", ret_val); 2307 return 0; 2308 } 2309 return ret_val; 2310 } 2311 2312 void G1CollectedHeap::deduplicate_string(oop str) { 2313 assert(java_lang_String::is_instance(str), "invariant"); 2314 2315 if (G1StringDedup::is_enabled()) { 2316 G1StringDedup::deduplicate(str); 2317 } 2318 } 2319 2320 void G1CollectedHeap::prepare_for_verify() { 2321 _verifier->prepare_for_verify(); 2322 } 2323 2324 void G1CollectedHeap::verify(VerifyOption vo) { 2325 _verifier->verify(vo); 2326 } 2327 2328 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2329 return true; 2330 } 2331 2332 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2333 return _cm_thread->request_concurrent_phase(phase); 2334 } 2335 2336 bool G1CollectedHeap::is_heterogeneous_heap() const { 2337 return G1Arguments::is_heterogeneous_heap(); 2338 } 2339 2340 class PrintRegionClosure: public HeapRegionClosure { 2341 outputStream* _st; 2342 public: 2343 PrintRegionClosure(outputStream* st) : _st(st) {} 2344 bool do_heap_region(HeapRegion* r) { 2345 r->print_on(_st); 2346 return false; 2347 } 2348 }; 2349 2350 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2351 const HeapRegion* hr, 2352 const VerifyOption vo) const { 2353 switch (vo) { 2354 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2355 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2356 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2357 default: ShouldNotReachHere(); 2358 } 2359 return false; // keep some compilers happy 2360 } 2361 2362 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2363 const VerifyOption vo) const { 2364 switch (vo) { 2365 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2366 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2367 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2368 default: ShouldNotReachHere(); 2369 } 2370 return false; // keep some compilers happy 2371 } 2372 2373 void G1CollectedHeap::print_heap_regions() const { 2374 LogTarget(Trace, gc, heap, region) lt; 2375 if (lt.is_enabled()) { 2376 LogStream ls(lt); 2377 print_regions_on(&ls); 2378 } 2379 } 2380 2381 void G1CollectedHeap::print_on(outputStream* st) const { 2382 st->print(" %-20s", "garbage-first heap"); 2383 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2384 capacity()/K, used_unlocked()/K); 2385 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2386 p2i(_hrm->reserved().start()), 2387 p2i(_hrm->reserved().end())); 2388 st->cr(); 2389 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2390 uint young_regions = young_regions_count(); 2391 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2392 (size_t) young_regions * HeapRegion::GrainBytes / K); 2393 uint survivor_regions = survivor_regions_count(); 2394 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2395 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2396 st->cr(); 2397 MetaspaceUtils::print_on(st); 2398 } 2399 2400 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2401 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2402 "HS=humongous(starts), HC=humongous(continues), " 2403 "CS=collection set, F=free, " 2404 "OA=open archive, CA=closed archive, " 2405 "TAMS=top-at-mark-start (previous, next)"); 2406 PrintRegionClosure blk(st); 2407 heap_region_iterate(&blk); 2408 } 2409 2410 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2411 print_on(st); 2412 2413 // Print the per-region information. 2414 print_regions_on(st); 2415 } 2416 2417 void G1CollectedHeap::print_on_error(outputStream* st) const { 2418 this->CollectedHeap::print_on_error(st); 2419 2420 if (_cm != NULL) { 2421 st->cr(); 2422 _cm->print_on_error(st); 2423 } 2424 } 2425 2426 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2427 workers()->print_worker_threads_on(st); 2428 _cm_thread->print_on(st); 2429 st->cr(); 2430 _cm->print_worker_threads_on(st); 2431 _cr->print_threads_on(st); 2432 _young_gen_sampling_thread->print_on(st); 2433 if (G1StringDedup::is_enabled()) { 2434 G1StringDedup::print_worker_threads_on(st); 2435 } 2436 } 2437 2438 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2439 workers()->threads_do(tc); 2440 tc->do_thread(_cm_thread); 2441 _cm->threads_do(tc); 2442 _cr->threads_do(tc); 2443 tc->do_thread(_young_gen_sampling_thread); 2444 if (G1StringDedup::is_enabled()) { 2445 G1StringDedup::threads_do(tc); 2446 } 2447 } 2448 2449 void G1CollectedHeap::print_tracing_info() const { 2450 rem_set()->print_summary_info(); 2451 concurrent_mark()->print_summary_info(); 2452 } 2453 2454 #ifndef PRODUCT 2455 // Helpful for debugging RSet issues. 2456 2457 class PrintRSetsClosure : public HeapRegionClosure { 2458 private: 2459 const char* _msg; 2460 size_t _occupied_sum; 2461 2462 public: 2463 bool do_heap_region(HeapRegion* r) { 2464 HeapRegionRemSet* hrrs = r->rem_set(); 2465 size_t occupied = hrrs->occupied(); 2466 _occupied_sum += occupied; 2467 2468 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2469 if (occupied == 0) { 2470 tty->print_cr(" RSet is empty"); 2471 } else { 2472 hrrs->print(); 2473 } 2474 tty->print_cr("----------"); 2475 return false; 2476 } 2477 2478 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2479 tty->cr(); 2480 tty->print_cr("========================================"); 2481 tty->print_cr("%s", msg); 2482 tty->cr(); 2483 } 2484 2485 ~PrintRSetsClosure() { 2486 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2487 tty->print_cr("========================================"); 2488 tty->cr(); 2489 } 2490 }; 2491 2492 void G1CollectedHeap::print_cset_rsets() { 2493 PrintRSetsClosure cl("Printing CSet RSets"); 2494 collection_set_iterate_all(&cl); 2495 } 2496 2497 void G1CollectedHeap::print_all_rsets() { 2498 PrintRSetsClosure cl("Printing All RSets");; 2499 heap_region_iterate(&cl); 2500 } 2501 #endif // PRODUCT 2502 2503 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2504 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2505 } 2506 2507 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2508 2509 size_t eden_used_bytes = _eden.used_bytes(); 2510 size_t survivor_used_bytes = _survivor.used_bytes(); 2511 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2512 2513 size_t eden_capacity_bytes = 2514 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2515 2516 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2517 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2518 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2519 } 2520 2521 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2522 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2523 stats->unused(), stats->used(), stats->region_end_waste(), 2524 stats->regions_filled(), stats->direct_allocated(), 2525 stats->failure_used(), stats->failure_waste()); 2526 } 2527 2528 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2529 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2530 gc_tracer->report_gc_heap_summary(when, heap_summary); 2531 2532 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2533 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2534 } 2535 2536 G1CollectedHeap* G1CollectedHeap::heap() { 2537 CollectedHeap* heap = Universe::heap(); 2538 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2539 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2540 return (G1CollectedHeap*)heap; 2541 } 2542 2543 void G1CollectedHeap::gc_prologue(bool full) { 2544 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2545 2546 // This summary needs to be printed before incrementing total collections. 2547 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2548 2549 // Update common counters. 2550 increment_total_collections(full /* full gc */); 2551 if (full || collector_state()->in_initial_mark_gc()) { 2552 increment_old_marking_cycles_started(); 2553 } 2554 2555 // Fill TLAB's and such 2556 double start = os::elapsedTime(); 2557 ensure_parsability(true); 2558 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2559 } 2560 2561 void G1CollectedHeap::gc_epilogue(bool full) { 2562 // Update common counters. 2563 if (full) { 2564 // Update the number of full collections that have been completed. 2565 increment_old_marking_cycles_completed(false /* concurrent */); 2566 } 2567 2568 // We are at the end of the GC. Total collections has already been increased. 2569 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2570 2571 // FIXME: what is this about? 2572 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2573 // is set. 2574 #if COMPILER2_OR_JVMCI 2575 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2576 #endif 2577 2578 double start = os::elapsedTime(); 2579 resize_all_tlabs(); 2580 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2581 2582 MemoryService::track_memory_usage(); 2583 // We have just completed a GC. Update the soft reference 2584 // policy with the new heap occupancy 2585 Universe::update_heap_info_at_gc(); 2586 } 2587 2588 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2589 uint gc_count_before, 2590 bool* succeeded, 2591 GCCause::Cause gc_cause) { 2592 assert_heap_not_locked_and_not_at_safepoint(); 2593 VM_G1CollectForAllocation op(word_size, 2594 gc_count_before, 2595 gc_cause, 2596 false, /* should_initiate_conc_mark */ 2597 policy()->max_pause_time_ms()); 2598 VMThread::execute(&op); 2599 2600 HeapWord* result = op.result(); 2601 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2602 assert(result == NULL || ret_succeeded, 2603 "the result should be NULL if the VM did not succeed"); 2604 *succeeded = ret_succeeded; 2605 2606 assert_heap_not_locked(); 2607 return result; 2608 } 2609 2610 void G1CollectedHeap::do_concurrent_mark() { 2611 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2612 if (!_cm_thread->in_progress()) { 2613 _cm_thread->set_started(); 2614 CGC_lock->notify(); 2615 } 2616 } 2617 2618 size_t G1CollectedHeap::pending_card_num() { 2619 struct CountCardsClosure : public ThreadClosure { 2620 size_t _cards; 2621 CountCardsClosure() : _cards(0) {} 2622 virtual void do_thread(Thread* t) { 2623 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2624 } 2625 } count_from_threads; 2626 Threads::threads_do(&count_from_threads); 2627 2628 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2629 dcqs.verify_num_cards(); 2630 2631 return dcqs.num_cards() + count_from_threads._cards; 2632 } 2633 2634 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2635 // We don't nominate objects with many remembered set entries, on 2636 // the assumption that such objects are likely still live. 2637 HeapRegionRemSet* rem_set = r->rem_set(); 2638 2639 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2640 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2641 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2642 } 2643 2644 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2645 private: 2646 size_t _total_humongous; 2647 size_t _candidate_humongous; 2648 2649 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2650 assert(region->is_starts_humongous(), "Must start a humongous object"); 2651 2652 oop obj = oop(region->bottom()); 2653 2654 // Dead objects cannot be eager reclaim candidates. Due to class 2655 // unloading it is unsafe to query their classes so we return early. 2656 if (g1h->is_obj_dead(obj, region)) { 2657 return false; 2658 } 2659 2660 // If we do not have a complete remembered set for the region, then we can 2661 // not be sure that we have all references to it. 2662 if (!region->rem_set()->is_complete()) { 2663 return false; 2664 } 2665 // Candidate selection must satisfy the following constraints 2666 // while concurrent marking is in progress: 2667 // 2668 // * In order to maintain SATB invariants, an object must not be 2669 // reclaimed if it was allocated before the start of marking and 2670 // has not had its references scanned. Such an object must have 2671 // its references (including type metadata) scanned to ensure no 2672 // live objects are missed by the marking process. Objects 2673 // allocated after the start of concurrent marking don't need to 2674 // be scanned. 2675 // 2676 // * An object must not be reclaimed if it is on the concurrent 2677 // mark stack. Objects allocated after the start of concurrent 2678 // marking are never pushed on the mark stack. 2679 // 2680 // Nominating only objects allocated after the start of concurrent 2681 // marking is sufficient to meet both constraints. This may miss 2682 // some objects that satisfy the constraints, but the marking data 2683 // structures don't support efficiently performing the needed 2684 // additional tests or scrubbing of the mark stack. 2685 // 2686 // However, we presently only nominate is_typeArray() objects. 2687 // A humongous object containing references induces remembered 2688 // set entries on other regions. In order to reclaim such an 2689 // object, those remembered sets would need to be cleaned up. 2690 // 2691 // We also treat is_typeArray() objects specially, allowing them 2692 // to be reclaimed even if allocated before the start of 2693 // concurrent mark. For this we rely on mark stack insertion to 2694 // exclude is_typeArray() objects, preventing reclaiming an object 2695 // that is in the mark stack. We also rely on the metadata for 2696 // such objects to be built-in and so ensured to be kept live. 2697 // Frequent allocation and drop of large binary blobs is an 2698 // important use case for eager reclaim, and this special handling 2699 // may reduce needed headroom. 2700 2701 return obj->is_typeArray() && 2702 g1h->is_potential_eager_reclaim_candidate(region); 2703 } 2704 2705 public: 2706 RegisterRegionsWithRegionAttrTableClosure() 2707 : _total_humongous(0), 2708 _candidate_humongous(0) { 2709 } 2710 2711 virtual bool do_heap_region(HeapRegion* r) { 2712 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2713 2714 if (!r->is_starts_humongous()) { 2715 g1h->register_region_with_region_attr(r); 2716 return false; 2717 } 2718 2719 bool is_candidate = humongous_region_is_candidate(g1h, r); 2720 uint rindex = r->hrm_index(); 2721 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2722 if (is_candidate) { 2723 g1h->register_humongous_region_with_region_attr(rindex); 2724 _candidate_humongous++; 2725 // We will later handle the remembered sets of these regions. 2726 } else { 2727 g1h->register_region_with_region_attr(r); 2728 } 2729 _total_humongous++; 2730 2731 return false; 2732 } 2733 2734 size_t total_humongous() const { return _total_humongous; } 2735 size_t candidate_humongous() const { return _candidate_humongous; } 2736 }; 2737 2738 void G1CollectedHeap::register_regions_with_region_attr() { 2739 Ticks start = Ticks::now(); 2740 2741 RegisterRegionsWithRegionAttrTableClosure cl; 2742 heap_region_iterate(&cl); 2743 2744 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2745 cl.total_humongous(), 2746 cl.candidate_humongous()); 2747 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2748 } 2749 2750 #ifndef PRODUCT 2751 void G1CollectedHeap::verify_region_attr_remset_update() { 2752 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2753 public: 2754 virtual bool do_heap_region(HeapRegion* r) { 2755 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2756 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2757 assert(r->rem_set()->is_tracked() == needs_remset_update, 2758 "Region %u remset tracking status (%s) different to region attribute (%s)", 2759 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2760 return false; 2761 } 2762 } cl; 2763 heap_region_iterate(&cl); 2764 } 2765 #endif 2766 2767 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2768 public: 2769 bool do_heap_region(HeapRegion* hr) { 2770 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2771 hr->verify_rem_set(); 2772 } 2773 return false; 2774 } 2775 }; 2776 2777 uint G1CollectedHeap::num_task_queues() const { 2778 return _task_queues->size(); 2779 } 2780 2781 #if TASKQUEUE_STATS 2782 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2783 st->print_raw_cr("GC Task Stats"); 2784 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2785 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2786 } 2787 2788 void G1CollectedHeap::print_taskqueue_stats() const { 2789 if (!log_is_enabled(Trace, gc, task, stats)) { 2790 return; 2791 } 2792 Log(gc, task, stats) log; 2793 ResourceMark rm; 2794 LogStream ls(log.trace()); 2795 outputStream* st = &ls; 2796 2797 print_taskqueue_stats_hdr(st); 2798 2799 TaskQueueStats totals; 2800 const uint n = num_task_queues(); 2801 for (uint i = 0; i < n; ++i) { 2802 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2803 totals += task_queue(i)->stats; 2804 } 2805 st->print_raw("tot "); totals.print(st); st->cr(); 2806 2807 DEBUG_ONLY(totals.verify()); 2808 } 2809 2810 void G1CollectedHeap::reset_taskqueue_stats() { 2811 const uint n = num_task_queues(); 2812 for (uint i = 0; i < n; ++i) { 2813 task_queue(i)->stats.reset(); 2814 } 2815 } 2816 #endif // TASKQUEUE_STATS 2817 2818 void G1CollectedHeap::wait_for_root_region_scanning() { 2819 double scan_wait_start = os::elapsedTime(); 2820 // We have to wait until the CM threads finish scanning the 2821 // root regions as it's the only way to ensure that all the 2822 // objects on them have been correctly scanned before we start 2823 // moving them during the GC. 2824 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2825 double wait_time_ms = 0.0; 2826 if (waited) { 2827 double scan_wait_end = os::elapsedTime(); 2828 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2829 } 2830 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2831 } 2832 2833 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2834 private: 2835 G1HRPrinter* _hr_printer; 2836 public: 2837 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2838 2839 virtual bool do_heap_region(HeapRegion* r) { 2840 _hr_printer->cset(r); 2841 return false; 2842 } 2843 }; 2844 2845 void G1CollectedHeap::start_new_collection_set() { 2846 double start = os::elapsedTime(); 2847 2848 collection_set()->start_incremental_building(); 2849 2850 clear_region_attr(); 2851 2852 guarantee(_eden.length() == 0, "eden should have been cleared"); 2853 policy()->transfer_survivors_to_cset(survivor()); 2854 2855 // We redo the verification but now wrt to the new CSet which 2856 // has just got initialized after the previous CSet was freed. 2857 _cm->verify_no_collection_set_oops(); 2858 2859 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2860 } 2861 2862 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2863 2864 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2865 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2866 collection_set()->optional_region_length()); 2867 2868 _cm->verify_no_collection_set_oops(); 2869 2870 if (_hr_printer.is_active()) { 2871 G1PrintCollectionSetClosure cl(&_hr_printer); 2872 _collection_set.iterate(&cl); 2873 _collection_set.iterate_optional(&cl); 2874 } 2875 } 2876 2877 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2878 if (collector_state()->in_initial_mark_gc()) { 2879 return G1HeapVerifier::G1VerifyConcurrentStart; 2880 } else if (collector_state()->in_young_only_phase()) { 2881 return G1HeapVerifier::G1VerifyYoungNormal; 2882 } else { 2883 return G1HeapVerifier::G1VerifyMixed; 2884 } 2885 } 2886 2887 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2888 if (VerifyRememberedSets) { 2889 log_info(gc, verify)("[Verifying RemSets before GC]"); 2890 VerifyRegionRemSetClosure v_cl; 2891 heap_region_iterate(&v_cl); 2892 } 2893 _verifier->verify_before_gc(type); 2894 _verifier->check_bitmaps("GC Start"); 2895 } 2896 2897 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2898 if (VerifyRememberedSets) { 2899 log_info(gc, verify)("[Verifying RemSets after GC]"); 2900 VerifyRegionRemSetClosure v_cl; 2901 heap_region_iterate(&v_cl); 2902 } 2903 _verifier->verify_after_gc(type); 2904 _verifier->check_bitmaps("GC End"); 2905 } 2906 2907 void G1CollectedHeap::expand_heap_after_young_collection(){ 2908 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2909 if (expand_bytes > 0) { 2910 // No need for an ergo logging here, 2911 // expansion_amount() does this when it returns a value > 0. 2912 double expand_ms; 2913 if (!expand(expand_bytes, _workers, &expand_ms)) { 2914 // We failed to expand the heap. Cannot do anything about it. 2915 } 2916 phase_times()->record_expand_heap_time(expand_ms); 2917 } 2918 } 2919 2920 const char* G1CollectedHeap::young_gc_name() const { 2921 if (collector_state()->in_initial_mark_gc()) { 2922 return "Pause Young (Concurrent Start)"; 2923 } else if (collector_state()->in_young_only_phase()) { 2924 if (collector_state()->in_young_gc_before_mixed()) { 2925 return "Pause Young (Prepare Mixed)"; 2926 } else { 2927 return "Pause Young (Normal)"; 2928 } 2929 } else { 2930 return "Pause Young (Mixed)"; 2931 } 2932 } 2933 2934 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2935 assert_at_safepoint_on_vm_thread(); 2936 guarantee(!is_gc_active(), "collection is not reentrant"); 2937 2938 if (GCLocker::check_active_before_gc()) { 2939 return false; 2940 } 2941 2942 GCIdMark gc_id_mark; 2943 2944 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2945 ResourceMark rm; 2946 2947 policy()->note_gc_start(); 2948 2949 _gc_timer_stw->register_gc_start(); 2950 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2951 2952 wait_for_root_region_scanning(); 2953 2954 print_heap_before_gc(); 2955 print_heap_regions(); 2956 trace_heap_before_gc(_gc_tracer_stw); 2957 2958 _verifier->verify_region_sets_optional(); 2959 _verifier->verify_dirty_young_regions(); 2960 2961 // We should not be doing initial mark unless the conc mark thread is running 2962 if (!_cm_thread->should_terminate()) { 2963 // This call will decide whether this pause is an initial-mark 2964 // pause. If it is, in_initial_mark_gc() will return true 2965 // for the duration of this pause. 2966 policy()->decide_on_conc_mark_initiation(); 2967 } 2968 2969 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2970 assert(!collector_state()->in_initial_mark_gc() || 2971 collector_state()->in_young_only_phase(), "sanity"); 2972 // We also do not allow mixed GCs during marking. 2973 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2974 2975 // Record whether this pause is an initial mark. When the current 2976 // thread has completed its logging output and it's safe to signal 2977 // the CM thread, the flag's value in the policy has been reset. 2978 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2979 if (should_start_conc_mark) { 2980 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2981 } 2982 2983 // Inner scope for scope based logging, timers, and stats collection 2984 { 2985 G1EvacuationInfo evacuation_info; 2986 2987 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2988 2989 GCTraceCPUTime tcpu; 2990 2991 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 2992 2993 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2994 workers()->active_workers(), 2995 Threads::number_of_non_daemon_threads()); 2996 active_workers = workers()->update_active_workers(active_workers); 2997 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2998 2999 G1MonitoringScope ms(g1mm(), 3000 false /* full_gc */, 3001 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3002 3003 G1HeapTransition heap_transition(this); 3004 size_t heap_used_bytes_before_gc = used(); 3005 3006 { 3007 IsGCActiveMark x; 3008 3009 gc_prologue(false); 3010 3011 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3012 verify_before_young_collection(verify_type); 3013 3014 { 3015 // The elapsed time induced by the start time below deliberately elides 3016 // the possible verification above. 3017 double sample_start_time_sec = os::elapsedTime(); 3018 3019 // Please see comment in g1CollectedHeap.hpp and 3020 // G1CollectedHeap::ref_processing_init() to see how 3021 // reference processing currently works in G1. 3022 _ref_processor_stw->enable_discovery(); 3023 3024 // We want to temporarily turn off discovery by the 3025 // CM ref processor, if necessary, and turn it back on 3026 // on again later if we do. Using a scoped 3027 // NoRefDiscovery object will do this. 3028 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3029 3030 policy()->record_collection_pause_start(sample_start_time_sec); 3031 3032 // Forget the current allocation region (we might even choose it to be part 3033 // of the collection set!). 3034 _allocator->release_mutator_alloc_regions(); 3035 3036 calculate_collection_set(evacuation_info, target_pause_time_ms); 3037 3038 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3039 G1ParScanThreadStateSet per_thread_states(this, 3040 &rdcqs, 3041 workers()->active_workers(), 3042 collection_set()->young_region_length(), 3043 collection_set()->optional_region_length()); 3044 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3045 3046 // Actually do the work... 3047 evacuate_initial_collection_set(&per_thread_states); 3048 3049 if (_collection_set.optional_region_length() != 0) { 3050 evacuate_optional_collection_set(&per_thread_states); 3051 } 3052 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3053 3054 start_new_collection_set(); 3055 3056 _survivor_evac_stats.adjust_desired_plab_sz(); 3057 _old_evac_stats.adjust_desired_plab_sz(); 3058 3059 if (should_start_conc_mark) { 3060 // We have to do this before we notify the CM threads that 3061 // they can start working to make sure that all the 3062 // appropriate initialization is done on the CM object. 3063 concurrent_mark()->post_initial_mark(); 3064 // Note that we don't actually trigger the CM thread at 3065 // this point. We do that later when we're sure that 3066 // the current thread has completed its logging output. 3067 } 3068 3069 allocate_dummy_regions(); 3070 3071 _allocator->init_mutator_alloc_regions(); 3072 3073 expand_heap_after_young_collection(); 3074 3075 double sample_end_time_sec = os::elapsedTime(); 3076 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3077 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc); 3078 } 3079 3080 verify_after_young_collection(verify_type); 3081 3082 #ifdef TRACESPINNING 3083 ParallelTaskTerminator::print_termination_counts(); 3084 #endif 3085 3086 gc_epilogue(false); 3087 } 3088 3089 // Print the remainder of the GC log output. 3090 if (evacuation_failed()) { 3091 log_info(gc)("To-space exhausted"); 3092 } 3093 3094 policy()->print_phases(); 3095 heap_transition.print(); 3096 3097 _hrm->verify_optional(); 3098 _verifier->verify_region_sets_optional(); 3099 3100 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3101 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3102 3103 print_heap_after_gc(); 3104 print_heap_regions(); 3105 trace_heap_after_gc(_gc_tracer_stw); 3106 3107 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3108 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3109 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3110 // before any GC notifications are raised. 3111 g1mm()->update_sizes(); 3112 3113 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3114 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3115 _gc_timer_stw->register_gc_end(); 3116 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3117 } 3118 // It should now be safe to tell the concurrent mark thread to start 3119 // without its logging output interfering with the logging output 3120 // that came from the pause. 3121 3122 if (should_start_conc_mark) { 3123 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3124 // thread(s) could be running concurrently with us. Make sure that anything 3125 // after this point does not assume that we are the only GC thread running. 3126 // Note: of course, the actual marking work will not start until the safepoint 3127 // itself is released in SuspendibleThreadSet::desynchronize(). 3128 do_concurrent_mark(); 3129 } 3130 3131 return true; 3132 } 3133 3134 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3135 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3136 workers()->run_task(&rsfp_task); 3137 } 3138 3139 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3140 double remove_self_forwards_start = os::elapsedTime(); 3141 3142 remove_self_forwarding_pointers(rdcqs); 3143 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3144 _preserved_marks_set.restore(&task_executor); 3145 3146 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3147 } 3148 3149 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3150 if (!_evacuation_failed) { 3151 _evacuation_failed = true; 3152 } 3153 3154 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3155 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3156 } 3157 3158 bool G1ParEvacuateFollowersClosure::offer_termination() { 3159 EventGCPhaseParallel event; 3160 G1ParScanThreadState* const pss = par_scan_state(); 3161 start_term_time(); 3162 const bool res = terminator()->offer_termination(); 3163 end_term_time(); 3164 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3165 return res; 3166 } 3167 3168 void G1ParEvacuateFollowersClosure::do_void() { 3169 EventGCPhaseParallel event; 3170 G1ParScanThreadState* const pss = par_scan_state(); 3171 pss->trim_queue(); 3172 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3173 do { 3174 EventGCPhaseParallel event; 3175 pss->steal_and_trim_queue(queues()); 3176 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3177 } while (!offer_termination()); 3178 } 3179 3180 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3181 bool class_unloading_occurred) { 3182 uint num_workers = workers()->active_workers(); 3183 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3184 workers()->run_task(&unlink_task); 3185 } 3186 3187 // Clean string dedup data structures. 3188 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3189 // record the durations of the phases. Hence the almost-copy. 3190 class G1StringDedupCleaningTask : public AbstractGangTask { 3191 BoolObjectClosure* _is_alive; 3192 OopClosure* _keep_alive; 3193 G1GCPhaseTimes* _phase_times; 3194 3195 public: 3196 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3197 OopClosure* keep_alive, 3198 G1GCPhaseTimes* phase_times) : 3199 AbstractGangTask("Partial Cleaning Task"), 3200 _is_alive(is_alive), 3201 _keep_alive(keep_alive), 3202 _phase_times(phase_times) 3203 { 3204 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3205 StringDedup::gc_prologue(true); 3206 } 3207 3208 ~G1StringDedupCleaningTask() { 3209 StringDedup::gc_epilogue(); 3210 } 3211 3212 void work(uint worker_id) { 3213 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3214 { 3215 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3216 StringDedupQueue::unlink_or_oops_do(&cl); 3217 } 3218 { 3219 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3220 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3221 } 3222 } 3223 }; 3224 3225 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3226 OopClosure* keep_alive, 3227 G1GCPhaseTimes* phase_times) { 3228 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3229 workers()->run_task(&cl); 3230 } 3231 3232 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3233 private: 3234 G1RedirtyCardsQueueSet* _qset; 3235 G1CollectedHeap* _g1h; 3236 BufferNode* volatile _nodes; 3237 3238 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3239 size_t buffer_size = _qset->buffer_size(); 3240 BufferNode* next = Atomic::load(&_nodes); 3241 while (next != NULL) { 3242 BufferNode* node = next; 3243 next = Atomic::cmpxchg(node->next(), &_nodes, node); 3244 if (next == node) { 3245 cl->apply_to_buffer(node, buffer_size, worker_id); 3246 next = node->next(); 3247 } 3248 } 3249 } 3250 3251 public: 3252 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3253 AbstractGangTask("Redirty Cards"), 3254 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3255 3256 virtual void work(uint worker_id) { 3257 G1GCPhaseTimes* p = _g1h->phase_times(); 3258 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3259 3260 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3261 par_apply(&cl, worker_id); 3262 3263 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3264 } 3265 }; 3266 3267 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3268 double redirty_logged_cards_start = os::elapsedTime(); 3269 3270 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3271 workers()->run_task(&redirty_task); 3272 3273 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3274 dcq.merge_bufferlists(rdcqs); 3275 3276 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3277 } 3278 3279 // Weak Reference Processing support 3280 3281 bool G1STWIsAliveClosure::do_object_b(oop p) { 3282 // An object is reachable if it is outside the collection set, 3283 // or is inside and copied. 3284 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3285 } 3286 3287 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3288 assert(obj != NULL, "must not be NULL"); 3289 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3290 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3291 // may falsely indicate that this is not the case here: however the collection set only 3292 // contains old regions when concurrent mark is not running. 3293 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3294 } 3295 3296 // Non Copying Keep Alive closure 3297 class G1KeepAliveClosure: public OopClosure { 3298 G1CollectedHeap*_g1h; 3299 public: 3300 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3301 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3302 void do_oop(oop* p) { 3303 oop obj = *p; 3304 assert(obj != NULL, "the caller should have filtered out NULL values"); 3305 3306 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3307 if (!region_attr.is_in_cset_or_humongous()) { 3308 return; 3309 } 3310 if (region_attr.is_in_cset()) { 3311 assert( obj->is_forwarded(), "invariant" ); 3312 *p = obj->forwardee(); 3313 } else { 3314 assert(!obj->is_forwarded(), "invariant" ); 3315 assert(region_attr.is_humongous(), 3316 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3317 _g1h->set_humongous_is_live(obj); 3318 } 3319 } 3320 }; 3321 3322 // Copying Keep Alive closure - can be called from both 3323 // serial and parallel code as long as different worker 3324 // threads utilize different G1ParScanThreadState instances 3325 // and different queues. 3326 3327 class G1CopyingKeepAliveClosure: public OopClosure { 3328 G1CollectedHeap* _g1h; 3329 G1ParScanThreadState* _par_scan_state; 3330 3331 public: 3332 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3333 G1ParScanThreadState* pss): 3334 _g1h(g1h), 3335 _par_scan_state(pss) 3336 {} 3337 3338 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3339 virtual void do_oop( oop* p) { do_oop_work(p); } 3340 3341 template <class T> void do_oop_work(T* p) { 3342 oop obj = RawAccess<>::oop_load(p); 3343 3344 if (_g1h->is_in_cset_or_humongous(obj)) { 3345 // If the referent object has been forwarded (either copied 3346 // to a new location or to itself in the event of an 3347 // evacuation failure) then we need to update the reference 3348 // field and, if both reference and referent are in the G1 3349 // heap, update the RSet for the referent. 3350 // 3351 // If the referent has not been forwarded then we have to keep 3352 // it alive by policy. Therefore we have copy the referent. 3353 // 3354 // When the queue is drained (after each phase of reference processing) 3355 // the object and it's followers will be copied, the reference field set 3356 // to point to the new location, and the RSet updated. 3357 _par_scan_state->push_on_queue(p); 3358 } 3359 } 3360 }; 3361 3362 // Serial drain queue closure. Called as the 'complete_gc' 3363 // closure for each discovered list in some of the 3364 // reference processing phases. 3365 3366 class G1STWDrainQueueClosure: public VoidClosure { 3367 protected: 3368 G1CollectedHeap* _g1h; 3369 G1ParScanThreadState* _par_scan_state; 3370 3371 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3372 3373 public: 3374 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3375 _g1h(g1h), 3376 _par_scan_state(pss) 3377 { } 3378 3379 void do_void() { 3380 G1ParScanThreadState* const pss = par_scan_state(); 3381 pss->trim_queue(); 3382 } 3383 }; 3384 3385 // Parallel Reference Processing closures 3386 3387 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3388 // processing during G1 evacuation pauses. 3389 3390 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3391 private: 3392 G1CollectedHeap* _g1h; 3393 G1ParScanThreadStateSet* _pss; 3394 RefToScanQueueSet* _queues; 3395 WorkGang* _workers; 3396 3397 public: 3398 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3399 G1ParScanThreadStateSet* per_thread_states, 3400 WorkGang* workers, 3401 RefToScanQueueSet *task_queues) : 3402 _g1h(g1h), 3403 _pss(per_thread_states), 3404 _queues(task_queues), 3405 _workers(workers) 3406 { 3407 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3408 } 3409 3410 // Executes the given task using concurrent marking worker threads. 3411 virtual void execute(ProcessTask& task, uint ergo_workers); 3412 }; 3413 3414 // Gang task for possibly parallel reference processing 3415 3416 class G1STWRefProcTaskProxy: public AbstractGangTask { 3417 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3418 ProcessTask& _proc_task; 3419 G1CollectedHeap* _g1h; 3420 G1ParScanThreadStateSet* _pss; 3421 RefToScanQueueSet* _task_queues; 3422 ParallelTaskTerminator* _terminator; 3423 3424 public: 3425 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3426 G1CollectedHeap* g1h, 3427 G1ParScanThreadStateSet* per_thread_states, 3428 RefToScanQueueSet *task_queues, 3429 ParallelTaskTerminator* terminator) : 3430 AbstractGangTask("Process reference objects in parallel"), 3431 _proc_task(proc_task), 3432 _g1h(g1h), 3433 _pss(per_thread_states), 3434 _task_queues(task_queues), 3435 _terminator(terminator) 3436 {} 3437 3438 virtual void work(uint worker_id) { 3439 // The reference processing task executed by a single worker. 3440 ResourceMark rm; 3441 HandleMark hm; 3442 3443 G1STWIsAliveClosure is_alive(_g1h); 3444 3445 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3446 pss->set_ref_discoverer(NULL); 3447 3448 // Keep alive closure. 3449 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3450 3451 // Complete GC closure 3452 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3453 3454 // Call the reference processing task's work routine. 3455 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3456 3457 // Note we cannot assert that the refs array is empty here as not all 3458 // of the processing tasks (specifically phase2 - pp2_work) execute 3459 // the complete_gc closure (which ordinarily would drain the queue) so 3460 // the queue may not be empty. 3461 } 3462 }; 3463 3464 // Driver routine for parallel reference processing. 3465 // Creates an instance of the ref processing gang 3466 // task and has the worker threads execute it. 3467 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3468 assert(_workers != NULL, "Need parallel worker threads."); 3469 3470 assert(_workers->active_workers() >= ergo_workers, 3471 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3472 ergo_workers, _workers->active_workers()); 3473 TaskTerminator terminator(ergo_workers, _queues); 3474 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3475 3476 _workers->run_task(&proc_task_proxy, ergo_workers); 3477 } 3478 3479 // End of weak reference support closures 3480 3481 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3482 double ref_proc_start = os::elapsedTime(); 3483 3484 ReferenceProcessor* rp = _ref_processor_stw; 3485 assert(rp->discovery_enabled(), "should have been enabled"); 3486 3487 // Closure to test whether a referent is alive. 3488 G1STWIsAliveClosure is_alive(this); 3489 3490 // Even when parallel reference processing is enabled, the processing 3491 // of JNI refs is serial and performed serially by the current thread 3492 // rather than by a worker. The following PSS will be used for processing 3493 // JNI refs. 3494 3495 // Use only a single queue for this PSS. 3496 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3497 pss->set_ref_discoverer(NULL); 3498 assert(pss->queue_is_empty(), "pre-condition"); 3499 3500 // Keep alive closure. 3501 G1CopyingKeepAliveClosure keep_alive(this, pss); 3502 3503 // Serial Complete GC closure 3504 G1STWDrainQueueClosure drain_queue(this, pss); 3505 3506 // Setup the soft refs policy... 3507 rp->setup_policy(false); 3508 3509 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3510 3511 ReferenceProcessorStats stats; 3512 if (!rp->processing_is_mt()) { 3513 // Serial reference processing... 3514 stats = rp->process_discovered_references(&is_alive, 3515 &keep_alive, 3516 &drain_queue, 3517 NULL, 3518 pt); 3519 } else { 3520 uint no_of_gc_workers = workers()->active_workers(); 3521 3522 // Parallel reference processing 3523 assert(no_of_gc_workers <= rp->max_num_queues(), 3524 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3525 no_of_gc_workers, rp->max_num_queues()); 3526 3527 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3528 stats = rp->process_discovered_references(&is_alive, 3529 &keep_alive, 3530 &drain_queue, 3531 &par_task_executor, 3532 pt); 3533 } 3534 3535 _gc_tracer_stw->report_gc_reference_stats(stats); 3536 3537 // We have completed copying any necessary live referent objects. 3538 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3539 3540 make_pending_list_reachable(); 3541 3542 assert(!rp->discovery_enabled(), "Postcondition"); 3543 rp->verify_no_references_recorded(); 3544 3545 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3546 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3547 } 3548 3549 void G1CollectedHeap::make_pending_list_reachable() { 3550 if (collector_state()->in_initial_mark_gc()) { 3551 oop pll_head = Universe::reference_pending_list(); 3552 if (pll_head != NULL) { 3553 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3554 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3555 } 3556 } 3557 } 3558 3559 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3560 double merge_pss_time_start = os::elapsedTime(); 3561 per_thread_states->flush(); 3562 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3563 } 3564 3565 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3566 _expand_heap_after_alloc_failure = true; 3567 _evacuation_failed = false; 3568 3569 // Disable the hot card cache. 3570 _hot_card_cache->reset_hot_cache_claimed_index(); 3571 _hot_card_cache->set_use_cache(false); 3572 3573 // Initialize the GC alloc regions. 3574 _allocator->init_gc_alloc_regions(evacuation_info); 3575 3576 { 3577 Ticks start = Ticks::now(); 3578 rem_set()->prepare_for_scan_heap_roots(); 3579 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3580 } 3581 3582 register_regions_with_region_attr(); 3583 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3584 3585 _preserved_marks_set.assert_empty(); 3586 3587 #if COMPILER2_OR_JVMCI 3588 DerivedPointerTable::clear(); 3589 #endif 3590 3591 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3592 if (collector_state()->in_initial_mark_gc()) { 3593 concurrent_mark()->pre_initial_mark(); 3594 3595 double start_clear_claimed_marks = os::elapsedTime(); 3596 3597 ClassLoaderDataGraph::clear_claimed_marks(); 3598 3599 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3600 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3601 } 3602 3603 // Should G1EvacuationFailureALot be in effect for this GC? 3604 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3605 } 3606 3607 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3608 protected: 3609 G1CollectedHeap* _g1h; 3610 G1ParScanThreadStateSet* _per_thread_states; 3611 RefToScanQueueSet* _task_queues; 3612 TaskTerminator _terminator; 3613 uint _num_workers; 3614 3615 void evacuate_live_objects(G1ParScanThreadState* pss, 3616 uint worker_id, 3617 G1GCPhaseTimes::GCParPhases objcopy_phase, 3618 G1GCPhaseTimes::GCParPhases termination_phase) { 3619 G1GCPhaseTimes* p = _g1h->phase_times(); 3620 3621 Ticks start = Ticks::now(); 3622 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase); 3623 cl.do_void(); 3624 3625 assert(pss->queue_is_empty(), "should be empty"); 3626 3627 Tickspan evac_time = (Ticks::now() - start); 3628 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3629 3630 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste); 3631 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste); 3632 3633 if (termination_phase == G1GCPhaseTimes::Termination) { 3634 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3635 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3636 } else { 3637 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3638 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3639 } 3640 } 3641 3642 virtual void start_work(uint worker_id) { } 3643 3644 virtual void end_work(uint worker_id) { } 3645 3646 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3647 3648 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3649 3650 public: 3651 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3652 AbstractGangTask(name), 3653 _g1h(G1CollectedHeap::heap()), 3654 _per_thread_states(per_thread_states), 3655 _task_queues(task_queues), 3656 _terminator(num_workers, _task_queues), 3657 _num_workers(num_workers) 3658 { } 3659 3660 void work(uint worker_id) { 3661 start_work(worker_id); 3662 3663 { 3664 ResourceMark rm; 3665 HandleMark hm; 3666 3667 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3668 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3669 3670 scan_roots(pss, worker_id); 3671 evacuate_live_objects(pss, worker_id); 3672 } 3673 3674 end_work(worker_id); 3675 } 3676 }; 3677 3678 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3679 G1RootProcessor* _root_processor; 3680 3681 void verify_trim_ticks(G1ParScanThreadState* pss, const char* location) { 3682 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation at %s %.3lf " JLONG_FORMAT, location, pss->trim_ticks().seconds(), pss->trim_ticks().value()); 3683 } 3684 3685 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3686 _root_processor->evacuate_roots(pss, worker_id); 3687 verify_trim_ticks(pss, "roots"); 3688 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3689 verify_trim_ticks(pss, "heap roots"); 3690 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3691 verify_trim_ticks(pss, "scan cset"); 3692 } 3693 3694 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3695 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3696 verify_trim_ticks(pss, "evac live"); 3697 } 3698 3699 void start_work(uint worker_id) { 3700 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3701 } 3702 3703 void end_work(uint worker_id) { 3704 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3705 } 3706 3707 public: 3708 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3709 G1ParScanThreadStateSet* per_thread_states, 3710 RefToScanQueueSet* task_queues, 3711 G1RootProcessor* root_processor, 3712 uint num_workers) : 3713 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3714 _root_processor(root_processor) 3715 { } 3716 }; 3717 3718 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3719 G1GCPhaseTimes* p = phase_times(); 3720 3721 { 3722 Ticks start = Ticks::now(); 3723 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3724 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3725 } 3726 3727 Tickspan task_time; 3728 const uint num_workers = workers()->active_workers(); 3729 3730 Ticks start_processing = Ticks::now(); 3731 { 3732 G1RootProcessor root_processor(this, num_workers); 3733 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3734 task_time = run_task(&g1_par_task); 3735 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3736 // To extract its code root fixup time we measure total time of this scope and 3737 // subtract from the time the WorkGang task took. 3738 } 3739 Tickspan total_processing = Ticks::now() - start_processing; 3740 3741 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3742 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3743 } 3744 3745 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3746 3747 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3748 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3749 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3750 } 3751 3752 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3753 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3754 } 3755 3756 public: 3757 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3758 RefToScanQueueSet* queues, 3759 uint num_workers) : 3760 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3761 } 3762 }; 3763 3764 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3765 class G1MarkScope : public MarkScope { }; 3766 3767 Tickspan task_time; 3768 3769 Ticks start_processing = Ticks::now(); 3770 { 3771 G1MarkScope code_mark_scope; 3772 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3773 task_time = run_task(&task); 3774 // See comment in evacuate_collection_set() for the reason of the scope. 3775 } 3776 Tickspan total_processing = Ticks::now() - start_processing; 3777 3778 G1GCPhaseTimes* p = phase_times(); 3779 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3780 } 3781 3782 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3783 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3784 3785 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3786 3787 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3788 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3789 3790 if (time_left_ms < 0 || 3791 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3792 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3793 _collection_set.optional_region_length(), time_left_ms); 3794 break; 3795 } 3796 3797 { 3798 Ticks start = Ticks::now(); 3799 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3800 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3801 } 3802 3803 { 3804 Ticks start = Ticks::now(); 3805 evacuate_next_optional_regions(per_thread_states); 3806 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3807 } 3808 } 3809 3810 _collection_set.abandon_optional_collection_set(per_thread_states); 3811 } 3812 3813 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3814 G1RedirtyCardsQueueSet* rdcqs, 3815 G1ParScanThreadStateSet* per_thread_states) { 3816 rem_set()->cleanup_after_scan_heap_roots(); 3817 3818 // Process any discovered reference objects - we have 3819 // to do this _before_ we retire the GC alloc regions 3820 // as we may have to copy some 'reachable' referent 3821 // objects (and their reachable sub-graphs) that were 3822 // not copied during the pause. 3823 process_discovered_references(per_thread_states); 3824 3825 G1STWIsAliveClosure is_alive(this); 3826 G1KeepAliveClosure keep_alive(this); 3827 3828 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3829 phase_times()->weak_phase_times()); 3830 3831 if (G1StringDedup::is_enabled()) { 3832 double string_dedup_time_ms = os::elapsedTime(); 3833 3834 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3835 3836 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3837 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3838 } 3839 3840 _allocator->release_gc_alloc_regions(evacuation_info); 3841 3842 if (evacuation_failed()) { 3843 restore_after_evac_failure(rdcqs); 3844 3845 // Reset the G1EvacuationFailureALot counters and flags 3846 NOT_PRODUCT(reset_evacuation_should_fail();) 3847 3848 double recalculate_used_start = os::elapsedTime(); 3849 set_used(recalculate_used()); 3850 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3851 3852 if (_archive_allocator != NULL) { 3853 _archive_allocator->clear_used(); 3854 } 3855 for (uint i = 0; i < ParallelGCThreads; i++) { 3856 if (_evacuation_failed_info_array[i].has_failed()) { 3857 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3858 } 3859 } 3860 } else { 3861 // The "used" of the the collection set have already been subtracted 3862 // when they were freed. Add in the bytes evacuated. 3863 increase_used(policy()->bytes_copied_during_gc()); 3864 } 3865 3866 _preserved_marks_set.assert_empty(); 3867 3868 merge_per_thread_state_info(per_thread_states); 3869 3870 // Reset and re-enable the hot card cache. 3871 // Note the counts for the cards in the regions in the 3872 // collection set are reset when the collection set is freed. 3873 _hot_card_cache->reset_hot_cache(); 3874 _hot_card_cache->set_use_cache(true); 3875 3876 purge_code_root_memory(); 3877 3878 redirty_logged_cards(rdcqs); 3879 3880 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3881 3882 eagerly_reclaim_humongous_regions(); 3883 3884 record_obj_copy_mem_stats(); 3885 3886 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3887 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3888 3889 #if COMPILER2_OR_JVMCI 3890 double start = os::elapsedTime(); 3891 DerivedPointerTable::update_pointers(); 3892 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3893 #endif 3894 policy()->print_age_table(); 3895 } 3896 3897 void G1CollectedHeap::record_obj_copy_mem_stats() { 3898 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3899 3900 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3901 create_g1_evac_summary(&_old_evac_stats)); 3902 } 3903 3904 void G1CollectedHeap::free_region(HeapRegion* hr, 3905 FreeRegionList* free_list, 3906 bool skip_remset, 3907 bool skip_hot_card_cache, 3908 bool locked) { 3909 assert(!hr->is_free(), "the region should not be free"); 3910 assert(!hr->is_empty(), "the region should not be empty"); 3911 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3912 assert(free_list != NULL, "pre-condition"); 3913 3914 if (G1VerifyBitmaps) { 3915 MemRegion mr(hr->bottom(), hr->end()); 3916 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3917 } 3918 3919 // Clear the card counts for this region. 3920 // Note: we only need to do this if the region is not young 3921 // (since we don't refine cards in young regions). 3922 if (!skip_hot_card_cache && !hr->is_young()) { 3923 _hot_card_cache->reset_card_counts(hr); 3924 } 3925 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3926 _policy->remset_tracker()->update_at_free(hr); 3927 free_list->add_ordered(hr); 3928 } 3929 3930 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3931 FreeRegionList* free_list) { 3932 assert(hr->is_humongous(), "this is only for humongous regions"); 3933 assert(free_list != NULL, "pre-condition"); 3934 hr->clear_humongous(); 3935 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3936 } 3937 3938 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3939 const uint humongous_regions_removed) { 3940 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3941 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3942 _old_set.bulk_remove(old_regions_removed); 3943 _humongous_set.bulk_remove(humongous_regions_removed); 3944 } 3945 3946 } 3947 3948 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3949 assert(list != NULL, "list can't be null"); 3950 if (!list->is_empty()) { 3951 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3952 _hrm->insert_list_into_free_list(list); 3953 } 3954 } 3955 3956 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3957 decrease_used(bytes); 3958 } 3959 3960 class G1FreeCollectionSetTask : public AbstractGangTask { 3961 private: 3962 3963 // Closure applied to all regions in the collection set to do work that needs to 3964 // be done serially in a single thread. 3965 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3966 private: 3967 G1EvacuationInfo* _evacuation_info; 3968 const size_t* _surviving_young_words; 3969 3970 // Bytes used in successfully evacuated regions before the evacuation. 3971 size_t _before_used_bytes; 3972 // Bytes used in unsucessfully evacuated regions before the evacuation 3973 size_t _after_used_bytes; 3974 3975 size_t _bytes_allocated_in_old_since_last_gc; 3976 3977 size_t _failure_used_words; 3978 size_t _failure_waste_words; 3979 3980 FreeRegionList _local_free_list; 3981 public: 3982 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3983 HeapRegionClosure(), 3984 _evacuation_info(evacuation_info), 3985 _surviving_young_words(surviving_young_words), 3986 _before_used_bytes(0), 3987 _after_used_bytes(0), 3988 _bytes_allocated_in_old_since_last_gc(0), 3989 _failure_used_words(0), 3990 _failure_waste_words(0), 3991 _local_free_list("Local Region List for CSet Freeing") { 3992 } 3993 3994 virtual bool do_heap_region(HeapRegion* r) { 3995 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3996 3997 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3998 g1h->clear_region_attr(r); 3999 4000 if (r->is_young()) { 4001 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(), 4002 "Young index %u is wrong for region %u of type %s with %u young regions", 4003 r->young_index_in_cset(), 4004 r->hrm_index(), 4005 r->get_type_str(), 4006 g1h->collection_set()->young_region_length()); 4007 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4008 r->record_surv_words_in_group(words_survived); 4009 } 4010 4011 if (!r->evacuation_failed()) { 4012 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4013 _before_used_bytes += r->used(); 4014 g1h->free_region(r, 4015 &_local_free_list, 4016 true, /* skip_remset */ 4017 true, /* skip_hot_card_cache */ 4018 true /* locked */); 4019 } else { 4020 r->uninstall_surv_rate_group(); 4021 r->clear_young_index_in_cset(); 4022 r->set_evacuation_failed(false); 4023 // When moving a young gen region to old gen, we "allocate" that whole region 4024 // there. This is in addition to any already evacuated objects. Notify the 4025 // policy about that. 4026 // Old gen regions do not cause an additional allocation: both the objects 4027 // still in the region and the ones already moved are accounted for elsewhere. 4028 if (r->is_young()) { 4029 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4030 } 4031 // The region is now considered to be old. 4032 r->set_old(); 4033 // Do some allocation statistics accounting. Regions that failed evacuation 4034 // are always made old, so there is no need to update anything in the young 4035 // gen statistics, but we need to update old gen statistics. 4036 size_t used_words = r->marked_bytes() / HeapWordSize; 4037 4038 _failure_used_words += used_words; 4039 _failure_waste_words += HeapRegion::GrainWords - used_words; 4040 4041 g1h->old_set_add(r); 4042 _after_used_bytes += r->used(); 4043 } 4044 return false; 4045 } 4046 4047 void complete_work() { 4048 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4049 4050 _evacuation_info->set_regions_freed(_local_free_list.length()); 4051 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4052 4053 g1h->prepend_to_freelist(&_local_free_list); 4054 g1h->decrement_summary_bytes(_before_used_bytes); 4055 4056 G1Policy* policy = g1h->policy(); 4057 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4058 4059 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4060 } 4061 }; 4062 4063 G1CollectionSet* _collection_set; 4064 G1SerialFreeCollectionSetClosure _cl; 4065 const size_t* _surviving_young_words; 4066 4067 size_t _rs_length; 4068 4069 volatile jint _serial_work_claim; 4070 4071 struct WorkItem { 4072 uint region_idx; 4073 bool is_young; 4074 bool evacuation_failed; 4075 4076 WorkItem(HeapRegion* r) { 4077 region_idx = r->hrm_index(); 4078 is_young = r->is_young(); 4079 evacuation_failed = r->evacuation_failed(); 4080 } 4081 }; 4082 4083 volatile size_t _parallel_work_claim; 4084 size_t _num_work_items; 4085 WorkItem* _work_items; 4086 4087 void do_serial_work() { 4088 // Need to grab the lock to be allowed to modify the old region list. 4089 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4090 _collection_set->iterate(&_cl); 4091 } 4092 4093 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4094 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4095 4096 HeapRegion* r = g1h->region_at(region_idx); 4097 assert(!g1h->is_on_master_free_list(r), "sanity"); 4098 4099 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length); 4100 4101 if (!is_young) { 4102 g1h->_hot_card_cache->reset_card_counts(r); 4103 } 4104 4105 if (!evacuation_failed) { 4106 r->rem_set()->clear_locked(); 4107 } 4108 } 4109 4110 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4111 private: 4112 size_t _cur_idx; 4113 WorkItem* _work_items; 4114 public: 4115 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4116 4117 virtual bool do_heap_region(HeapRegion* r) { 4118 _work_items[_cur_idx++] = WorkItem(r); 4119 return false; 4120 } 4121 }; 4122 4123 void prepare_work() { 4124 G1PrepareFreeCollectionSetClosure cl(_work_items); 4125 _collection_set->iterate(&cl); 4126 } 4127 4128 void complete_work() { 4129 _cl.complete_work(); 4130 4131 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4132 policy->record_max_rs_length(_rs_length); 4133 policy->cset_regions_freed(); 4134 } 4135 public: 4136 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4137 AbstractGangTask("G1 Free Collection Set"), 4138 _collection_set(collection_set), 4139 _cl(evacuation_info, surviving_young_words), 4140 _surviving_young_words(surviving_young_words), 4141 _rs_length(0), 4142 _serial_work_claim(0), 4143 _parallel_work_claim(0), 4144 _num_work_items(collection_set->region_length()), 4145 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4146 prepare_work(); 4147 } 4148 4149 ~G1FreeCollectionSetTask() { 4150 complete_work(); 4151 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4152 } 4153 4154 // Chunk size for work distribution. The chosen value has been determined experimentally 4155 // to be a good tradeoff between overhead and achievable parallelism. 4156 static uint chunk_size() { return 32; } 4157 4158 virtual void work(uint worker_id) { 4159 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4160 4161 // Claim serial work. 4162 if (_serial_work_claim == 0) { 4163 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4164 if (value == 0) { 4165 double serial_time = os::elapsedTime(); 4166 do_serial_work(); 4167 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4168 } 4169 } 4170 4171 // Start parallel work. 4172 double young_time = 0.0; 4173 bool has_young_time = false; 4174 double non_young_time = 0.0; 4175 bool has_non_young_time = false; 4176 4177 while (true) { 4178 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4179 size_t cur = end - chunk_size(); 4180 4181 if (cur >= _num_work_items) { 4182 break; 4183 } 4184 4185 EventGCPhaseParallel event; 4186 double start_time = os::elapsedTime(); 4187 4188 end = MIN2(end, _num_work_items); 4189 4190 for (; cur < end; cur++) { 4191 bool is_young = _work_items[cur].is_young; 4192 4193 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4194 4195 double end_time = os::elapsedTime(); 4196 double time_taken = end_time - start_time; 4197 if (is_young) { 4198 young_time += time_taken; 4199 has_young_time = true; 4200 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4201 } else { 4202 non_young_time += time_taken; 4203 has_non_young_time = true; 4204 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4205 } 4206 start_time = end_time; 4207 } 4208 } 4209 4210 if (has_young_time) { 4211 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4212 } 4213 if (has_non_young_time) { 4214 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4215 } 4216 } 4217 }; 4218 4219 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4220 _eden.clear(); 4221 4222 double free_cset_start_time = os::elapsedTime(); 4223 4224 { 4225 uint const num_regions = _collection_set.region_length(); 4226 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4227 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4228 4229 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4230 4231 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4232 cl.name(), num_workers, num_regions); 4233 workers()->run_task(&cl, num_workers); 4234 } 4235 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4236 4237 collection_set->clear(); 4238 } 4239 4240 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4241 private: 4242 FreeRegionList* _free_region_list; 4243 HeapRegionSet* _proxy_set; 4244 uint _humongous_objects_reclaimed; 4245 uint _humongous_regions_reclaimed; 4246 size_t _freed_bytes; 4247 public: 4248 4249 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4250 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4251 } 4252 4253 virtual bool do_heap_region(HeapRegion* r) { 4254 if (!r->is_starts_humongous()) { 4255 return false; 4256 } 4257 4258 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4259 4260 oop obj = (oop)r->bottom(); 4261 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4262 4263 // The following checks whether the humongous object is live are sufficient. 4264 // The main additional check (in addition to having a reference from the roots 4265 // or the young gen) is whether the humongous object has a remembered set entry. 4266 // 4267 // A humongous object cannot be live if there is no remembered set for it 4268 // because: 4269 // - there can be no references from within humongous starts regions referencing 4270 // the object because we never allocate other objects into them. 4271 // (I.e. there are no intra-region references that may be missed by the 4272 // remembered set) 4273 // - as soon there is a remembered set entry to the humongous starts region 4274 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4275 // until the end of a concurrent mark. 4276 // 4277 // It is not required to check whether the object has been found dead by marking 4278 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4279 // all objects allocated during that time are considered live. 4280 // SATB marking is even more conservative than the remembered set. 4281 // So if at this point in the collection there is no remembered set entry, 4282 // nobody has a reference to it. 4283 // At the start of collection we flush all refinement logs, and remembered sets 4284 // are completely up-to-date wrt to references to the humongous object. 4285 // 4286 // Other implementation considerations: 4287 // - never consider object arrays at this time because they would pose 4288 // considerable effort for cleaning up the the remembered sets. This is 4289 // required because stale remembered sets might reference locations that 4290 // are currently allocated into. 4291 uint region_idx = r->hrm_index(); 4292 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4293 !r->rem_set()->is_empty()) { 4294 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", 4295 region_idx, 4296 (size_t)obj->size() * HeapWordSize, 4297 p2i(r->bottom()), 4298 r->rem_set()->occupied(), 4299 r->rem_set()->strong_code_roots_list_length(), 4300 next_bitmap->is_marked(r->bottom()), 4301 g1h->is_humongous_reclaim_candidate(region_idx), 4302 obj->is_typeArray() 4303 ); 4304 return false; 4305 } 4306 4307 guarantee(obj->is_typeArray(), 4308 "Only eagerly reclaiming type arrays is supported, but the object " 4309 PTR_FORMAT " is not.", p2i(r->bottom())); 4310 4311 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", 4312 region_idx, 4313 (size_t)obj->size() * HeapWordSize, 4314 p2i(r->bottom()), 4315 r->rem_set()->occupied(), 4316 r->rem_set()->strong_code_roots_list_length(), 4317 next_bitmap->is_marked(r->bottom()), 4318 g1h->is_humongous_reclaim_candidate(region_idx), 4319 obj->is_typeArray() 4320 ); 4321 4322 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4323 cm->humongous_object_eagerly_reclaimed(r); 4324 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4325 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4326 region_idx, 4327 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4328 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4329 _humongous_objects_reclaimed++; 4330 do { 4331 HeapRegion* next = g1h->next_region_in_humongous(r); 4332 _freed_bytes += r->used(); 4333 r->set_containing_set(NULL); 4334 _humongous_regions_reclaimed++; 4335 g1h->free_humongous_region(r, _free_region_list); 4336 r = next; 4337 } while (r != NULL); 4338 4339 return false; 4340 } 4341 4342 uint humongous_objects_reclaimed() { 4343 return _humongous_objects_reclaimed; 4344 } 4345 4346 uint humongous_regions_reclaimed() { 4347 return _humongous_regions_reclaimed; 4348 } 4349 4350 size_t bytes_freed() const { 4351 return _freed_bytes; 4352 } 4353 }; 4354 4355 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4356 assert_at_safepoint_on_vm_thread(); 4357 4358 if (!G1EagerReclaimHumongousObjects || 4359 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4360 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4361 return; 4362 } 4363 4364 double start_time = os::elapsedTime(); 4365 4366 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4367 4368 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4369 heap_region_iterate(&cl); 4370 4371 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4372 4373 G1HRPrinter* hrp = hr_printer(); 4374 if (hrp->is_active()) { 4375 FreeRegionListIterator iter(&local_cleanup_list); 4376 while (iter.more_available()) { 4377 HeapRegion* hr = iter.get_next(); 4378 hrp->cleanup(hr); 4379 } 4380 } 4381 4382 prepend_to_freelist(&local_cleanup_list); 4383 decrement_summary_bytes(cl.bytes_freed()); 4384 4385 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4386 cl.humongous_objects_reclaimed()); 4387 } 4388 4389 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4390 public: 4391 virtual bool do_heap_region(HeapRegion* r) { 4392 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4393 G1CollectedHeap::heap()->clear_region_attr(r); 4394 r->clear_young_index_in_cset(); 4395 return false; 4396 } 4397 }; 4398 4399 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4400 G1AbandonCollectionSetClosure cl; 4401 collection_set_iterate_all(&cl); 4402 4403 collection_set->clear(); 4404 collection_set->stop_incremental_building(); 4405 } 4406 4407 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4408 return _allocator->is_retained_old_region(hr); 4409 } 4410 4411 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4412 _eden.add(hr); 4413 _policy->set_region_eden(hr); 4414 } 4415 4416 #ifdef ASSERT 4417 4418 class NoYoungRegionsClosure: public HeapRegionClosure { 4419 private: 4420 bool _success; 4421 public: 4422 NoYoungRegionsClosure() : _success(true) { } 4423 bool do_heap_region(HeapRegion* r) { 4424 if (r->is_young()) { 4425 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4426 p2i(r->bottom()), p2i(r->end())); 4427 _success = false; 4428 } 4429 return false; 4430 } 4431 bool success() { return _success; } 4432 }; 4433 4434 bool G1CollectedHeap::check_young_list_empty() { 4435 bool ret = (young_regions_count() == 0); 4436 4437 NoYoungRegionsClosure closure; 4438 heap_region_iterate(&closure); 4439 ret = ret && closure.success(); 4440 4441 return ret; 4442 } 4443 4444 #endif // ASSERT 4445 4446 class TearDownRegionSetsClosure : public HeapRegionClosure { 4447 HeapRegionSet *_old_set; 4448 4449 public: 4450 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4451 4452 bool do_heap_region(HeapRegion* r) { 4453 if (r->is_old()) { 4454 _old_set->remove(r); 4455 } else if(r->is_young()) { 4456 r->uninstall_surv_rate_group(); 4457 } else { 4458 // We ignore free regions, we'll empty the free list afterwards. 4459 // We ignore humongous and archive regions, we're not tearing down these 4460 // sets. 4461 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4462 "it cannot be another type"); 4463 } 4464 return false; 4465 } 4466 4467 ~TearDownRegionSetsClosure() { 4468 assert(_old_set->is_empty(), "post-condition"); 4469 } 4470 }; 4471 4472 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4473 assert_at_safepoint_on_vm_thread(); 4474 4475 if (!free_list_only) { 4476 TearDownRegionSetsClosure cl(&_old_set); 4477 heap_region_iterate(&cl); 4478 4479 // Note that emptying the _young_list is postponed and instead done as 4480 // the first step when rebuilding the regions sets again. The reason for 4481 // this is that during a full GC string deduplication needs to know if 4482 // a collected region was young or old when the full GC was initiated. 4483 } 4484 _hrm->remove_all_free_regions(); 4485 } 4486 4487 void G1CollectedHeap::increase_used(size_t bytes) { 4488 _summary_bytes_used += bytes; 4489 } 4490 4491 void G1CollectedHeap::decrease_used(size_t bytes) { 4492 assert(_summary_bytes_used >= bytes, 4493 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4494 _summary_bytes_used, bytes); 4495 _summary_bytes_used -= bytes; 4496 } 4497 4498 void G1CollectedHeap::set_used(size_t bytes) { 4499 _summary_bytes_used = bytes; 4500 } 4501 4502 class RebuildRegionSetsClosure : public HeapRegionClosure { 4503 private: 4504 bool _free_list_only; 4505 4506 HeapRegionSet* _old_set; 4507 HeapRegionManager* _hrm; 4508 4509 size_t _total_used; 4510 4511 public: 4512 RebuildRegionSetsClosure(bool free_list_only, 4513 HeapRegionSet* old_set, 4514 HeapRegionManager* hrm) : 4515 _free_list_only(free_list_only), 4516 _old_set(old_set), _hrm(hrm), _total_used(0) { 4517 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4518 if (!free_list_only) { 4519 assert(_old_set->is_empty(), "pre-condition"); 4520 } 4521 } 4522 4523 bool do_heap_region(HeapRegion* r) { 4524 if (r->is_empty()) { 4525 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4526 // Add free regions to the free list 4527 r->set_free(); 4528 _hrm->insert_into_free_list(r); 4529 } else if (!_free_list_only) { 4530 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4531 4532 if (r->is_archive() || r->is_humongous()) { 4533 // We ignore archive and humongous regions. We left these sets unchanged. 4534 } else { 4535 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4536 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4537 r->move_to_old(); 4538 _old_set->add(r); 4539 } 4540 _total_used += r->used(); 4541 } 4542 4543 return false; 4544 } 4545 4546 size_t total_used() { 4547 return _total_used; 4548 } 4549 }; 4550 4551 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4552 assert_at_safepoint_on_vm_thread(); 4553 4554 if (!free_list_only) { 4555 _eden.clear(); 4556 _survivor.clear(); 4557 } 4558 4559 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4560 heap_region_iterate(&cl); 4561 4562 if (!free_list_only) { 4563 set_used(cl.total_used()); 4564 if (_archive_allocator != NULL) { 4565 _archive_allocator->clear_used(); 4566 } 4567 } 4568 assert_used_and_recalculate_used_equal(this); 4569 } 4570 4571 // Methods for the mutator alloc region 4572 4573 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4574 bool force, 4575 uint node_index) { 4576 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4577 bool should_allocate = policy()->should_allocate_mutator_region(); 4578 if (force || should_allocate) { 4579 HeapRegion* new_alloc_region = new_region(word_size, 4580 HeapRegionType::Eden, 4581 false /* do_expand */, 4582 node_index); 4583 if (new_alloc_region != NULL) { 4584 set_region_short_lived_locked(new_alloc_region); 4585 _hr_printer.alloc(new_alloc_region, !should_allocate); 4586 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4587 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4588 return new_alloc_region; 4589 } 4590 } 4591 return NULL; 4592 } 4593 4594 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4595 size_t allocated_bytes) { 4596 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4597 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4598 4599 collection_set()->add_eden_region(alloc_region); 4600 increase_used(allocated_bytes); 4601 _eden.add_used_bytes(allocated_bytes); 4602 _hr_printer.retire(alloc_region); 4603 4604 // We update the eden sizes here, when the region is retired, 4605 // instead of when it's allocated, since this is the point that its 4606 // used space has been recorded in _summary_bytes_used. 4607 g1mm()->update_eden_size(); 4608 } 4609 4610 // Methods for the GC alloc regions 4611 4612 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4613 if (dest.is_old()) { 4614 return true; 4615 } else { 4616 return survivor_regions_count() < policy()->max_survivor_regions(); 4617 } 4618 } 4619 4620 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) { 4621 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4622 4623 if (!has_more_regions(dest)) { 4624 return NULL; 4625 } 4626 4627 HeapRegionType type; 4628 if (dest.is_young()) { 4629 type = HeapRegionType::Survivor; 4630 } else { 4631 type = HeapRegionType::Old; 4632 } 4633 4634 HeapRegion* new_alloc_region = new_region(word_size, 4635 type, 4636 true /* do_expand */); 4637 4638 if (new_alloc_region != NULL) { 4639 if (type.is_survivor()) { 4640 new_alloc_region->set_survivor(); 4641 _survivor.add(new_alloc_region); 4642 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4643 } else { 4644 new_alloc_region->set_old(); 4645 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4646 } 4647 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4648 register_region_with_region_attr(new_alloc_region); 4649 _hr_printer.alloc(new_alloc_region); 4650 return new_alloc_region; 4651 } 4652 return NULL; 4653 } 4654 4655 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4656 size_t allocated_bytes, 4657 G1HeapRegionAttr dest) { 4658 policy()->record_bytes_copied_during_gc(allocated_bytes); 4659 if (dest.is_old()) { 4660 old_set_add(alloc_region); 4661 } else { 4662 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4663 _survivor.add_used_bytes(allocated_bytes); 4664 } 4665 4666 bool const during_im = collector_state()->in_initial_mark_gc(); 4667 if (during_im && allocated_bytes > 0) { 4668 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4669 } 4670 _hr_printer.retire(alloc_region); 4671 } 4672 4673 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4674 bool expanded = false; 4675 uint index = _hrm->find_highest_free(&expanded); 4676 4677 if (index != G1_NO_HRM_INDEX) { 4678 if (expanded) { 4679 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4680 HeapRegion::GrainWords * HeapWordSize); 4681 } 4682 _hrm->allocate_free_regions_starting_at(index, 1); 4683 return region_at(index); 4684 } 4685 return NULL; 4686 } 4687 4688 // Optimized nmethod scanning 4689 4690 class RegisterNMethodOopClosure: public OopClosure { 4691 G1CollectedHeap* _g1h; 4692 nmethod* _nm; 4693 4694 template <class T> void do_oop_work(T* p) { 4695 T heap_oop = RawAccess<>::oop_load(p); 4696 if (!CompressedOops::is_null(heap_oop)) { 4697 oop obj = CompressedOops::decode_not_null(heap_oop); 4698 HeapRegion* hr = _g1h->heap_region_containing(obj); 4699 assert(!hr->is_continues_humongous(), 4700 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4701 " starting at " HR_FORMAT, 4702 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4703 4704 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4705 hr->add_strong_code_root_locked(_nm); 4706 } 4707 } 4708 4709 public: 4710 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4711 _g1h(g1h), _nm(nm) {} 4712 4713 void do_oop(oop* p) { do_oop_work(p); } 4714 void do_oop(narrowOop* p) { do_oop_work(p); } 4715 }; 4716 4717 class UnregisterNMethodOopClosure: public OopClosure { 4718 G1CollectedHeap* _g1h; 4719 nmethod* _nm; 4720 4721 template <class T> void do_oop_work(T* p) { 4722 T heap_oop = RawAccess<>::oop_load(p); 4723 if (!CompressedOops::is_null(heap_oop)) { 4724 oop obj = CompressedOops::decode_not_null(heap_oop); 4725 HeapRegion* hr = _g1h->heap_region_containing(obj); 4726 assert(!hr->is_continues_humongous(), 4727 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4728 " starting at " HR_FORMAT, 4729 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4730 4731 hr->remove_strong_code_root(_nm); 4732 } 4733 } 4734 4735 public: 4736 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4737 _g1h(g1h), _nm(nm) {} 4738 4739 void do_oop(oop* p) { do_oop_work(p); } 4740 void do_oop(narrowOop* p) { do_oop_work(p); } 4741 }; 4742 4743 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4744 guarantee(nm != NULL, "sanity"); 4745 RegisterNMethodOopClosure reg_cl(this, nm); 4746 nm->oops_do(®_cl); 4747 } 4748 4749 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4750 guarantee(nm != NULL, "sanity"); 4751 UnregisterNMethodOopClosure reg_cl(this, nm); 4752 nm->oops_do(®_cl, true); 4753 } 4754 4755 void G1CollectedHeap::purge_code_root_memory() { 4756 double purge_start = os::elapsedTime(); 4757 G1CodeRootSet::purge(); 4758 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4759 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4760 } 4761 4762 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4763 G1CollectedHeap* _g1h; 4764 4765 public: 4766 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4767 _g1h(g1h) {} 4768 4769 void do_code_blob(CodeBlob* cb) { 4770 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4771 if (nm == NULL) { 4772 return; 4773 } 4774 4775 _g1h->register_nmethod(nm); 4776 } 4777 }; 4778 4779 void G1CollectedHeap::rebuild_strong_code_roots() { 4780 RebuildStrongCodeRootClosure blob_cl(this); 4781 CodeCache::blobs_do(&blob_cl); 4782 } 4783 4784 void G1CollectedHeap::initialize_serviceability() { 4785 _g1mm->initialize_serviceability(); 4786 } 4787 4788 MemoryUsage G1CollectedHeap::memory_usage() { 4789 return _g1mm->memory_usage(); 4790 } 4791 4792 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4793 return _g1mm->memory_managers(); 4794 } 4795 4796 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4797 return _g1mm->memory_pools(); 4798 }