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 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1394 1395 if (expanded_by == 0) { 1396 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1398 return false; 1399 } 1400 1401 policy()->record_new_heap_size(num_regions()); 1402 return true; 1403 } 1404 1405 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1406 size_t aligned_shrink_bytes = 1407 ReservedSpace::page_align_size_down(shrink_bytes); 1408 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1409 HeapRegion::GrainBytes); 1410 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1411 1412 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1413 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1414 1415 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B", 1416 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1417 if (num_regions_removed > 0) { 1418 policy()->record_new_heap_size(num_regions()); 1419 } else { 1420 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1421 } 1422 } 1423 1424 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1425 _verifier->verify_region_sets_optional(); 1426 1427 // We should only reach here at the end of a Full GC or during Remark which 1428 // means we should not not be holding to any GC alloc regions. The method 1429 // below will make sure of that and do any remaining clean up. 1430 _allocator->abandon_gc_alloc_regions(); 1431 1432 // Instead of tearing down / rebuilding the free lists here, we 1433 // could instead use the remove_all_pending() method on free_list to 1434 // remove only the ones that we need to remove. 1435 tear_down_region_sets(true /* free_list_only */); 1436 shrink_helper(shrink_bytes); 1437 rebuild_region_sets(true /* free_list_only */); 1438 1439 _hrm->verify_optional(); 1440 _verifier->verify_region_sets_optional(); 1441 } 1442 1443 class OldRegionSetChecker : public HeapRegionSetChecker { 1444 public: 1445 void check_mt_safety() { 1446 // Master Old Set MT safety protocol: 1447 // (a) If we're at a safepoint, operations on the master old set 1448 // should be invoked: 1449 // - by the VM thread (which will serialize them), or 1450 // - by the GC workers while holding the FreeList_lock, if we're 1451 // at a safepoint for an evacuation pause (this lock is taken 1452 // anyway when an GC alloc region is retired so that a new one 1453 // is allocated from the free list), or 1454 // - by the GC workers while holding the OldSets_lock, if we're at a 1455 // safepoint for a cleanup pause. 1456 // (b) If we're not at a safepoint, operations on the master old set 1457 // should be invoked while holding the Heap_lock. 1458 1459 if (SafepointSynchronize::is_at_safepoint()) { 1460 guarantee(Thread::current()->is_VM_thread() || 1461 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1462 "master old set MT safety protocol at a safepoint"); 1463 } else { 1464 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1465 } 1466 } 1467 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1468 const char* get_description() { return "Old Regions"; } 1469 }; 1470 1471 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1472 public: 1473 void check_mt_safety() { 1474 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1475 "May only change archive regions during initialization or safepoint."); 1476 } 1477 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1478 const char* get_description() { return "Archive Regions"; } 1479 }; 1480 1481 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1482 public: 1483 void check_mt_safety() { 1484 // Humongous Set MT safety protocol: 1485 // (a) If we're at a safepoint, operations on the master humongous 1486 // set should be invoked by either the VM thread (which will 1487 // serialize them) or by the GC workers while holding the 1488 // OldSets_lock. 1489 // (b) If we're not at a safepoint, operations on the master 1490 // humongous set should be invoked while holding the Heap_lock. 1491 1492 if (SafepointSynchronize::is_at_safepoint()) { 1493 guarantee(Thread::current()->is_VM_thread() || 1494 OldSets_lock->owned_by_self(), 1495 "master humongous set MT safety protocol at a safepoint"); 1496 } else { 1497 guarantee(Heap_lock->owned_by_self(), 1498 "master humongous set MT safety protocol outside a safepoint"); 1499 } 1500 } 1501 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1502 const char* get_description() { return "Humongous Regions"; } 1503 }; 1504 1505 G1CollectedHeap::G1CollectedHeap() : 1506 CollectedHeap(), 1507 _young_gen_sampling_thread(NULL), 1508 _workers(NULL), 1509 _card_table(NULL), 1510 _soft_ref_policy(), 1511 _old_set("Old Region Set", new OldRegionSetChecker()), 1512 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1513 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1514 _bot(NULL), 1515 _listener(), 1516 _numa(G1NUMA::create()), 1517 _hrm(NULL), 1518 _allocator(NULL), 1519 _verifier(NULL), 1520 _summary_bytes_used(0), 1521 _archive_allocator(NULL), 1522 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1523 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1524 _expand_heap_after_alloc_failure(true), 1525 _g1mm(NULL), 1526 _humongous_reclaim_candidates(), 1527 _has_humongous_reclaim_candidates(false), 1528 _hr_printer(), 1529 _collector_state(), 1530 _old_marking_cycles_started(0), 1531 _old_marking_cycles_completed(0), 1532 _eden(), 1533 _survivor(), 1534 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1535 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1536 _policy(G1Policy::create_policy(_gc_timer_stw)), 1537 _heap_sizing_policy(NULL), 1538 _collection_set(this, _policy), 1539 _hot_card_cache(NULL), 1540 _rem_set(NULL), 1541 _cm(NULL), 1542 _cm_thread(NULL), 1543 _cr(NULL), 1544 _task_queues(NULL), 1545 _evacuation_failed(false), 1546 _evacuation_failed_info_array(NULL), 1547 _preserved_marks_set(true /* in_c_heap */), 1548 #ifndef PRODUCT 1549 _evacuation_failure_alot_for_current_gc(false), 1550 _evacuation_failure_alot_gc_number(0), 1551 _evacuation_failure_alot_count(0), 1552 #endif 1553 _ref_processor_stw(NULL), 1554 _is_alive_closure_stw(this), 1555 _is_subject_to_discovery_stw(this), 1556 _ref_processor_cm(NULL), 1557 _is_alive_closure_cm(this), 1558 _is_subject_to_discovery_cm(this), 1559 _region_attr() { 1560 1561 _verifier = new G1HeapVerifier(this); 1562 1563 _allocator = new G1Allocator(this); 1564 1565 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1566 1567 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1568 1569 // Override the default _filler_array_max_size so that no humongous filler 1570 // objects are created. 1571 _filler_array_max_size = _humongous_object_threshold_in_words; 1572 1573 uint n_queues = ParallelGCThreads; 1574 _task_queues = new RefToScanQueueSet(n_queues); 1575 1576 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1577 1578 for (uint i = 0; i < n_queues; i++) { 1579 RefToScanQueue* q = new RefToScanQueue(); 1580 q->initialize(); 1581 _task_queues->register_queue(i, q); 1582 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1583 } 1584 1585 // Initialize the G1EvacuationFailureALot counters and flags. 1586 NOT_PRODUCT(reset_evacuation_should_fail();) 1587 _gc_tracer_stw->initialize(); 1588 1589 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1590 } 1591 1592 static size_t actual_reserved_page_size(ReservedSpace rs) { 1593 size_t page_size = os::vm_page_size(); 1594 if (UseLargePages) { 1595 // There are two ways to manage large page memory. 1596 // 1. OS supports committing large page memory. 1597 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1598 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1599 // we reserved memory without large page. 1600 if (os::can_commit_large_page_memory() || rs.special()) { 1601 // An alignment at ReservedSpace comes from preferred page size or 1602 // heap alignment, and if the alignment came from heap alignment, it could be 1603 // larger than large pages size. So need to cap with the large page size. 1604 page_size = MIN2(rs.alignment(), os::large_page_size()); 1605 } 1606 } 1607 1608 return page_size; 1609 } 1610 1611 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1612 size_t size, 1613 size_t translation_factor) { 1614 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1615 // Allocate a new reserved space, preferring to use large pages. 1616 ReservedSpace rs(size, preferred_page_size); 1617 size_t page_size = actual_reserved_page_size(rs); 1618 G1RegionToSpaceMapper* result = 1619 G1RegionToSpaceMapper::create_mapper(rs, 1620 size, 1621 page_size, 1622 HeapRegion::GrainBytes, 1623 translation_factor, 1624 mtGC); 1625 1626 os::trace_page_sizes_for_requested_size(description, 1627 size, 1628 preferred_page_size, 1629 page_size, 1630 rs.base(), 1631 rs.size()); 1632 1633 return result; 1634 } 1635 1636 jint G1CollectedHeap::initialize_concurrent_refinement() { 1637 jint ecode = JNI_OK; 1638 _cr = G1ConcurrentRefine::create(&ecode); 1639 return ecode; 1640 } 1641 1642 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1643 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1644 if (_young_gen_sampling_thread->osthread() == NULL) { 1645 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1646 return JNI_ENOMEM; 1647 } 1648 return JNI_OK; 1649 } 1650 1651 jint G1CollectedHeap::initialize() { 1652 os::enable_vtime(); 1653 1654 // Necessary to satisfy locking discipline assertions. 1655 1656 MutexLocker x(Heap_lock); 1657 1658 // While there are no constraints in the GC code that HeapWordSize 1659 // be any particular value, there are multiple other areas in the 1660 // system which believe this to be true (e.g. oop->object_size in some 1661 // cases incorrectly returns the size in wordSize units rather than 1662 // HeapWordSize). 1663 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1664 1665 size_t init_byte_size = InitialHeapSize; 1666 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1667 1668 // Ensure that the sizes are properly aligned. 1669 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1670 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1671 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1672 1673 // Reserve the maximum. 1674 1675 // When compressed oops are enabled, the preferred heap base 1676 // is calculated by subtracting the requested size from the 1677 // 32Gb boundary and using the result as the base address for 1678 // heap reservation. If the requested size is not aligned to 1679 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1680 // into the ReservedHeapSpace constructor) then the actual 1681 // base of the reserved heap may end up differing from the 1682 // address that was requested (i.e. the preferred heap base). 1683 // If this happens then we could end up using a non-optimal 1684 // compressed oops mode. 1685 1686 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1687 HeapAlignment); 1688 1689 initialize_reserved_region(heap_rs); 1690 1691 // Create the barrier set for the entire reserved region. 1692 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1693 ct->initialize(); 1694 G1BarrierSet* bs = new G1BarrierSet(ct); 1695 bs->initialize(); 1696 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1697 BarrierSet::set_barrier_set(bs); 1698 _card_table = ct; 1699 1700 { 1701 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1702 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1703 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1704 } 1705 1706 // Create the hot card cache. 1707 _hot_card_cache = new G1HotCardCache(this); 1708 1709 // Carve out the G1 part of the heap. 1710 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1711 size_t page_size = actual_reserved_page_size(heap_rs); 1712 G1RegionToSpaceMapper* heap_storage = 1713 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1714 g1_rs.size(), 1715 page_size, 1716 HeapRegion::GrainBytes, 1717 1, 1718 mtJavaHeap); 1719 if(heap_storage == NULL) { 1720 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1721 return JNI_ERR; 1722 } 1723 1724 os::trace_page_sizes("Heap", 1725 MinHeapSize, 1726 reserved_byte_size, 1727 page_size, 1728 heap_rs.base(), 1729 heap_rs.size()); 1730 heap_storage->set_mapping_changed_listener(&_listener); 1731 1732 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1733 G1RegionToSpaceMapper* bot_storage = 1734 create_aux_memory_mapper("Block Offset Table", 1735 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1736 G1BlockOffsetTable::heap_map_factor()); 1737 1738 G1RegionToSpaceMapper* cardtable_storage = 1739 create_aux_memory_mapper("Card Table", 1740 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1741 G1CardTable::heap_map_factor()); 1742 1743 G1RegionToSpaceMapper* card_counts_storage = 1744 create_aux_memory_mapper("Card Counts Table", 1745 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1746 G1CardCounts::heap_map_factor()); 1747 1748 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1749 G1RegionToSpaceMapper* prev_bitmap_storage = 1750 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1751 G1RegionToSpaceMapper* next_bitmap_storage = 1752 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1753 1754 _hrm = HeapRegionManager::create_manager(this); 1755 1756 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1757 _card_table->initialize(cardtable_storage); 1758 1759 // Do later initialization work for concurrent refinement. 1760 _hot_card_cache->initialize(card_counts_storage); 1761 1762 // 6843694 - ensure that the maximum region index can fit 1763 // in the remembered set structures. 1764 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1765 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1766 1767 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1768 // start within the first card. 1769 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1770 // Also create a G1 rem set. 1771 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1772 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1773 1774 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1775 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1776 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1777 "too many cards per region"); 1778 1779 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1780 1781 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1782 1783 { 1784 HeapWord* start = _hrm->reserved().start(); 1785 HeapWord* end = _hrm->reserved().end(); 1786 size_t granularity = HeapRegion::GrainBytes; 1787 1788 _region_attr.initialize(start, end, granularity); 1789 _humongous_reclaim_candidates.initialize(start, end, granularity); 1790 } 1791 1792 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1793 true /* are_GC_task_threads */, 1794 false /* are_ConcurrentGC_threads */); 1795 if (_workers == NULL) { 1796 return JNI_ENOMEM; 1797 } 1798 _workers->initialize_workers(); 1799 1800 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1801 1802 // Create the G1ConcurrentMark data structure and thread. 1803 // (Must do this late, so that "max_regions" is defined.) 1804 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1805 if (_cm == NULL || !_cm->completed_initialization()) { 1806 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1807 return JNI_ENOMEM; 1808 } 1809 _cm_thread = _cm->cm_thread(); 1810 1811 // Now expand into the initial heap size. 1812 if (!expand(init_byte_size, _workers)) { 1813 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1814 return JNI_ENOMEM; 1815 } 1816 1817 // Perform any initialization actions delegated to the policy. 1818 policy()->init(this, &_collection_set); 1819 1820 jint ecode = initialize_concurrent_refinement(); 1821 if (ecode != JNI_OK) { 1822 return ecode; 1823 } 1824 1825 ecode = initialize_young_gen_sampling_thread(); 1826 if (ecode != JNI_OK) { 1827 return ecode; 1828 } 1829 1830 { 1831 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1832 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1833 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1834 } 1835 1836 // Here we allocate the dummy HeapRegion that is required by the 1837 // G1AllocRegion class. 1838 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1839 1840 // We'll re-use the same region whether the alloc region will 1841 // require BOT updates or not and, if it doesn't, then a non-young 1842 // region will complain that it cannot support allocations without 1843 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1844 dummy_region->set_eden(); 1845 // Make sure it's full. 1846 dummy_region->set_top(dummy_region->end()); 1847 G1AllocRegion::setup(this, dummy_region); 1848 1849 _allocator->init_mutator_alloc_regions(); 1850 1851 // Do create of the monitoring and management support so that 1852 // values in the heap have been properly initialized. 1853 _g1mm = new G1MonitoringSupport(this); 1854 1855 G1StringDedup::initialize(); 1856 1857 _preserved_marks_set.init(ParallelGCThreads); 1858 1859 _collection_set.initialize(max_regions()); 1860 1861 return JNI_OK; 1862 } 1863 1864 void G1CollectedHeap::stop() { 1865 // Stop all concurrent threads. We do this to make sure these threads 1866 // do not continue to execute and access resources (e.g. logging) 1867 // that are destroyed during shutdown. 1868 _cr->stop(); 1869 _young_gen_sampling_thread->stop(); 1870 _cm_thread->stop(); 1871 if (G1StringDedup::is_enabled()) { 1872 G1StringDedup::stop(); 1873 } 1874 } 1875 1876 void G1CollectedHeap::safepoint_synchronize_begin() { 1877 SuspendibleThreadSet::synchronize(); 1878 } 1879 1880 void G1CollectedHeap::safepoint_synchronize_end() { 1881 SuspendibleThreadSet::desynchronize(); 1882 } 1883 1884 void G1CollectedHeap::post_initialize() { 1885 CollectedHeap::post_initialize(); 1886 ref_processing_init(); 1887 } 1888 1889 void G1CollectedHeap::ref_processing_init() { 1890 // Reference processing in G1 currently works as follows: 1891 // 1892 // * There are two reference processor instances. One is 1893 // used to record and process discovered references 1894 // during concurrent marking; the other is used to 1895 // record and process references during STW pauses 1896 // (both full and incremental). 1897 // * Both ref processors need to 'span' the entire heap as 1898 // the regions in the collection set may be dotted around. 1899 // 1900 // * For the concurrent marking ref processor: 1901 // * Reference discovery is enabled at initial marking. 1902 // * Reference discovery is disabled and the discovered 1903 // references processed etc during remarking. 1904 // * Reference discovery is MT (see below). 1905 // * Reference discovery requires a barrier (see below). 1906 // * Reference processing may or may not be MT 1907 // (depending on the value of ParallelRefProcEnabled 1908 // and ParallelGCThreads). 1909 // * A full GC disables reference discovery by the CM 1910 // ref processor and abandons any entries on it's 1911 // discovered lists. 1912 // 1913 // * For the STW processor: 1914 // * Non MT discovery is enabled at the start of a full GC. 1915 // * Processing and enqueueing during a full GC is non-MT. 1916 // * During a full GC, references are processed after marking. 1917 // 1918 // * Discovery (may or may not be MT) is enabled at the start 1919 // of an incremental evacuation pause. 1920 // * References are processed near the end of a STW evacuation pause. 1921 // * For both types of GC: 1922 // * Discovery is atomic - i.e. not concurrent. 1923 // * Reference discovery will not need a barrier. 1924 1925 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1926 1927 // Concurrent Mark ref processor 1928 _ref_processor_cm = 1929 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1930 mt_processing, // mt processing 1931 ParallelGCThreads, // degree of mt processing 1932 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1933 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1934 false, // Reference discovery is not atomic 1935 &_is_alive_closure_cm, // is alive closure 1936 true); // allow changes to number of processing threads 1937 1938 // STW ref processor 1939 _ref_processor_stw = 1940 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1941 mt_processing, // mt processing 1942 ParallelGCThreads, // degree of mt processing 1943 (ParallelGCThreads > 1), // mt discovery 1944 ParallelGCThreads, // degree of mt discovery 1945 true, // Reference discovery is atomic 1946 &_is_alive_closure_stw, // is alive closure 1947 true); // allow changes to number of processing threads 1948 } 1949 1950 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1951 return &_soft_ref_policy; 1952 } 1953 1954 size_t G1CollectedHeap::capacity() const { 1955 return _hrm->length() * HeapRegion::GrainBytes; 1956 } 1957 1958 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1959 return _hrm->total_free_bytes(); 1960 } 1961 1962 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1963 _hot_card_cache->drain(cl, worker_id); 1964 } 1965 1966 // Computes the sum of the storage used by the various regions. 1967 size_t G1CollectedHeap::used() const { 1968 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1969 if (_archive_allocator != NULL) { 1970 result += _archive_allocator->used(); 1971 } 1972 return result; 1973 } 1974 1975 size_t G1CollectedHeap::used_unlocked() const { 1976 return _summary_bytes_used; 1977 } 1978 1979 class SumUsedClosure: public HeapRegionClosure { 1980 size_t _used; 1981 public: 1982 SumUsedClosure() : _used(0) {} 1983 bool do_heap_region(HeapRegion* r) { 1984 _used += r->used(); 1985 return false; 1986 } 1987 size_t result() { return _used; } 1988 }; 1989 1990 size_t G1CollectedHeap::recalculate_used() const { 1991 SumUsedClosure blk; 1992 heap_region_iterate(&blk); 1993 return blk.result(); 1994 } 1995 1996 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1997 switch (cause) { 1998 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1999 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2000 case GCCause::_wb_conc_mark: return true; 2001 default : return false; 2002 } 2003 } 2004 2005 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2006 switch (cause) { 2007 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2008 case GCCause::_g1_humongous_allocation: return true; 2009 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2010 default: return is_user_requested_concurrent_full_gc(cause); 2011 } 2012 } 2013 2014 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2015 if(policy()->force_upgrade_to_full()) { 2016 return true; 2017 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2018 return false; 2019 } else if (has_regions_left_for_allocation()) { 2020 return false; 2021 } else { 2022 return true; 2023 } 2024 } 2025 2026 #ifndef PRODUCT 2027 void G1CollectedHeap::allocate_dummy_regions() { 2028 // Let's fill up most of the region 2029 size_t word_size = HeapRegion::GrainWords - 1024; 2030 // And as a result the region we'll allocate will be humongous. 2031 guarantee(is_humongous(word_size), "sanity"); 2032 2033 // _filler_array_max_size is set to humongous object threshold 2034 // but temporarily change it to use CollectedHeap::fill_with_object(). 2035 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2036 2037 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2038 // Let's use the existing mechanism for the allocation 2039 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2040 if (dummy_obj != NULL) { 2041 MemRegion mr(dummy_obj, word_size); 2042 CollectedHeap::fill_with_object(mr); 2043 } else { 2044 // If we can't allocate once, we probably cannot allocate 2045 // again. Let's get out of the loop. 2046 break; 2047 } 2048 } 2049 } 2050 #endif // !PRODUCT 2051 2052 void G1CollectedHeap::increment_old_marking_cycles_started() { 2053 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2054 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2055 "Wrong marking cycle count (started: %d, completed: %d)", 2056 _old_marking_cycles_started, _old_marking_cycles_completed); 2057 2058 _old_marking_cycles_started++; 2059 } 2060 2061 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2062 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2063 2064 // We assume that if concurrent == true, then the caller is a 2065 // concurrent thread that was joined the Suspendible Thread 2066 // Set. If there's ever a cheap way to check this, we should add an 2067 // assert here. 2068 2069 // Given that this method is called at the end of a Full GC or of a 2070 // concurrent cycle, and those can be nested (i.e., a Full GC can 2071 // interrupt a concurrent cycle), the number of full collections 2072 // completed should be either one (in the case where there was no 2073 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2074 // behind the number of full collections started. 2075 2076 // This is the case for the inner caller, i.e. a Full GC. 2077 assert(concurrent || 2078 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2079 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2080 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2081 "is inconsistent with _old_marking_cycles_completed = %u", 2082 _old_marking_cycles_started, _old_marking_cycles_completed); 2083 2084 // This is the case for the outer caller, i.e. the concurrent cycle. 2085 assert(!concurrent || 2086 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2087 "for outer caller (concurrent cycle): " 2088 "_old_marking_cycles_started = %u " 2089 "is inconsistent with _old_marking_cycles_completed = %u", 2090 _old_marking_cycles_started, _old_marking_cycles_completed); 2091 2092 _old_marking_cycles_completed += 1; 2093 2094 // We need to clear the "in_progress" flag in the CM thread before 2095 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2096 // is set) so that if a waiter requests another System.gc() it doesn't 2097 // incorrectly see that a marking cycle is still in progress. 2098 if (concurrent) { 2099 _cm_thread->set_idle(); 2100 } 2101 2102 // This notify_all() will ensure that a thread that called 2103 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2104 // and it's waiting for a full GC to finish will be woken up. It is 2105 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2106 FullGCCount_lock->notify_all(); 2107 } 2108 2109 void G1CollectedHeap::collect(GCCause::Cause cause) { 2110 try_collect(cause, true); 2111 } 2112 2113 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2114 assert_heap_not_locked(); 2115 2116 bool gc_succeeded; 2117 bool should_retry_gc; 2118 2119 do { 2120 should_retry_gc = false; 2121 2122 uint gc_count_before; 2123 uint old_marking_count_before; 2124 uint full_gc_count_before; 2125 2126 { 2127 MutexLocker ml(Heap_lock); 2128 2129 // Read the GC count while holding the Heap_lock 2130 gc_count_before = total_collections(); 2131 full_gc_count_before = total_full_collections(); 2132 old_marking_count_before = _old_marking_cycles_started; 2133 } 2134 2135 if (should_do_concurrent_full_gc(cause)) { 2136 // Schedule an initial-mark evacuation pause that will start a 2137 // concurrent cycle. We're setting word_size to 0 which means that 2138 // we are not requesting a post-GC allocation. 2139 VM_G1CollectForAllocation op(0, /* word_size */ 2140 gc_count_before, 2141 cause, 2142 true, /* should_initiate_conc_mark */ 2143 policy()->max_pause_time_ms()); 2144 VMThread::execute(&op); 2145 gc_succeeded = op.gc_succeeded(); 2146 if (!gc_succeeded && retry_on_gc_failure) { 2147 if (old_marking_count_before == _old_marking_cycles_started) { 2148 should_retry_gc = op.should_retry_gc(); 2149 } else { 2150 // A Full GC happened while we were trying to schedule the 2151 // concurrent cycle. No point in starting a new cycle given 2152 // that the whole heap was collected anyway. 2153 } 2154 2155 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2156 GCLocker::stall_until_clear(); 2157 } 2158 } 2159 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2160 // Return false to be consistent with VMOp failure due to 2161 // another collection slipping in after our gc_count but before 2162 // our request is processed. _gc_locker collections upgraded by 2163 // GCLockerInvokesConcurrent are handled above and never discarded. 2164 return false; 2165 } else { 2166 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2167 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2168 2169 // Schedule a standard evacuation pause. We're setting word_size 2170 // to 0 which means that we are not requesting a post-GC allocation. 2171 VM_G1CollectForAllocation op(0, /* word_size */ 2172 gc_count_before, 2173 cause, 2174 false, /* should_initiate_conc_mark */ 2175 policy()->max_pause_time_ms()); 2176 VMThread::execute(&op); 2177 gc_succeeded = op.gc_succeeded(); 2178 } else { 2179 // Schedule a Full GC. 2180 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2181 VMThread::execute(&op); 2182 gc_succeeded = op.gc_succeeded(); 2183 } 2184 } 2185 } while (should_retry_gc); 2186 return gc_succeeded; 2187 } 2188 2189 bool G1CollectedHeap::is_in(const void* p) const { 2190 if (_hrm->reserved().contains(p)) { 2191 // Given that we know that p is in the reserved space, 2192 // heap_region_containing() should successfully 2193 // return the containing region. 2194 HeapRegion* hr = heap_region_containing(p); 2195 return hr->is_in(p); 2196 } else { 2197 return false; 2198 } 2199 } 2200 2201 #ifdef ASSERT 2202 bool G1CollectedHeap::is_in_exact(const void* p) const { 2203 bool contains = reserved_region().contains(p); 2204 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2205 if (contains && available) { 2206 return true; 2207 } else { 2208 return false; 2209 } 2210 } 2211 #endif 2212 2213 // Iteration functions. 2214 2215 // Iterates an ObjectClosure over all objects within a HeapRegion. 2216 2217 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2218 ObjectClosure* _cl; 2219 public: 2220 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2221 bool do_heap_region(HeapRegion* r) { 2222 if (!r->is_continues_humongous()) { 2223 r->object_iterate(_cl); 2224 } 2225 return false; 2226 } 2227 }; 2228 2229 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2230 IterateObjectClosureRegionClosure blk(cl); 2231 heap_region_iterate(&blk); 2232 } 2233 2234 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2235 _hrm->iterate(cl); 2236 } 2237 2238 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2239 HeapRegionClaimer *hrclaimer, 2240 uint worker_id) const { 2241 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2242 } 2243 2244 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2245 HeapRegionClaimer *hrclaimer) const { 2246 _hrm->par_iterate(cl, hrclaimer, 0); 2247 } 2248 2249 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2250 _collection_set.iterate(cl); 2251 } 2252 2253 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2254 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2255 } 2256 2257 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2258 HeapRegion* hr = heap_region_containing(addr); 2259 return hr->block_start(addr); 2260 } 2261 2262 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2263 HeapRegion* hr = heap_region_containing(addr); 2264 return hr->block_is_obj(addr); 2265 } 2266 2267 bool G1CollectedHeap::supports_tlab_allocation() const { 2268 return true; 2269 } 2270 2271 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2272 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2273 } 2274 2275 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2276 return _eden.length() * HeapRegion::GrainBytes; 2277 } 2278 2279 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2280 // must be equal to the humongous object limit. 2281 size_t G1CollectedHeap::max_tlab_size() const { 2282 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2283 } 2284 2285 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2286 return _allocator->unsafe_max_tlab_alloc(); 2287 } 2288 2289 size_t G1CollectedHeap::max_capacity() const { 2290 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2291 } 2292 2293 size_t G1CollectedHeap::max_reserved_capacity() const { 2294 return _hrm->max_length() * HeapRegion::GrainBytes; 2295 } 2296 2297 jlong G1CollectedHeap::millis_since_last_gc() { 2298 // See the notes in GenCollectedHeap::millis_since_last_gc() 2299 // for more information about the implementation. 2300 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2301 _policy->collection_pause_end_millis(); 2302 if (ret_val < 0) { 2303 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2304 ". returning zero instead.", ret_val); 2305 return 0; 2306 } 2307 return ret_val; 2308 } 2309 2310 void G1CollectedHeap::deduplicate_string(oop str) { 2311 assert(java_lang_String::is_instance(str), "invariant"); 2312 2313 if (G1StringDedup::is_enabled()) { 2314 G1StringDedup::deduplicate(str); 2315 } 2316 } 2317 2318 void G1CollectedHeap::prepare_for_verify() { 2319 _verifier->prepare_for_verify(); 2320 } 2321 2322 void G1CollectedHeap::verify(VerifyOption vo) { 2323 _verifier->verify(vo); 2324 } 2325 2326 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2327 return true; 2328 } 2329 2330 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2331 return _cm_thread->request_concurrent_phase(phase); 2332 } 2333 2334 bool G1CollectedHeap::is_heterogeneous_heap() const { 2335 return G1Arguments::is_heterogeneous_heap(); 2336 } 2337 2338 class PrintRegionClosure: public HeapRegionClosure { 2339 outputStream* _st; 2340 public: 2341 PrintRegionClosure(outputStream* st) : _st(st) {} 2342 bool do_heap_region(HeapRegion* r) { 2343 r->print_on(_st); 2344 return false; 2345 } 2346 }; 2347 2348 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2349 const HeapRegion* hr, 2350 const VerifyOption vo) const { 2351 switch (vo) { 2352 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2353 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2354 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2355 default: ShouldNotReachHere(); 2356 } 2357 return false; // keep some compilers happy 2358 } 2359 2360 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2361 const VerifyOption vo) const { 2362 switch (vo) { 2363 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2364 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2365 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2366 default: ShouldNotReachHere(); 2367 } 2368 return false; // keep some compilers happy 2369 } 2370 2371 void G1CollectedHeap::print_heap_regions() const { 2372 LogTarget(Trace, gc, heap, region) lt; 2373 if (lt.is_enabled()) { 2374 LogStream ls(lt); 2375 print_regions_on(&ls); 2376 } 2377 } 2378 2379 void G1CollectedHeap::print_on(outputStream* st) const { 2380 st->print(" %-20s", "garbage-first heap"); 2381 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2382 capacity()/K, used_unlocked()/K); 2383 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2384 p2i(_hrm->reserved().start()), 2385 p2i(_hrm->reserved().end())); 2386 st->cr(); 2387 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2388 uint young_regions = young_regions_count(); 2389 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2390 (size_t) young_regions * HeapRegion::GrainBytes / K); 2391 uint survivor_regions = survivor_regions_count(); 2392 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2393 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2394 st->cr(); 2395 MetaspaceUtils::print_on(st); 2396 } 2397 2398 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2399 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2400 "HS=humongous(starts), HC=humongous(continues), " 2401 "CS=collection set, F=free, " 2402 "OA=open archive, CA=closed archive, " 2403 "TAMS=top-at-mark-start (previous, next)"); 2404 PrintRegionClosure blk(st); 2405 heap_region_iterate(&blk); 2406 } 2407 2408 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2409 print_on(st); 2410 2411 // Print the per-region information. 2412 print_regions_on(st); 2413 } 2414 2415 void G1CollectedHeap::print_on_error(outputStream* st) const { 2416 this->CollectedHeap::print_on_error(st); 2417 2418 if (_cm != NULL) { 2419 st->cr(); 2420 _cm->print_on_error(st); 2421 } 2422 } 2423 2424 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2425 workers()->print_worker_threads_on(st); 2426 _cm_thread->print_on(st); 2427 st->cr(); 2428 _cm->print_worker_threads_on(st); 2429 _cr->print_threads_on(st); 2430 _young_gen_sampling_thread->print_on(st); 2431 if (G1StringDedup::is_enabled()) { 2432 G1StringDedup::print_worker_threads_on(st); 2433 } 2434 } 2435 2436 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2437 workers()->threads_do(tc); 2438 tc->do_thread(_cm_thread); 2439 _cm->threads_do(tc); 2440 _cr->threads_do(tc); 2441 tc->do_thread(_young_gen_sampling_thread); 2442 if (G1StringDedup::is_enabled()) { 2443 G1StringDedup::threads_do(tc); 2444 } 2445 } 2446 2447 void G1CollectedHeap::print_tracing_info() const { 2448 rem_set()->print_summary_info(); 2449 concurrent_mark()->print_summary_info(); 2450 } 2451 2452 #ifndef PRODUCT 2453 // Helpful for debugging RSet issues. 2454 2455 class PrintRSetsClosure : public HeapRegionClosure { 2456 private: 2457 const char* _msg; 2458 size_t _occupied_sum; 2459 2460 public: 2461 bool do_heap_region(HeapRegion* r) { 2462 HeapRegionRemSet* hrrs = r->rem_set(); 2463 size_t occupied = hrrs->occupied(); 2464 _occupied_sum += occupied; 2465 2466 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2467 if (occupied == 0) { 2468 tty->print_cr(" RSet is empty"); 2469 } else { 2470 hrrs->print(); 2471 } 2472 tty->print_cr("----------"); 2473 return false; 2474 } 2475 2476 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2477 tty->cr(); 2478 tty->print_cr("========================================"); 2479 tty->print_cr("%s", msg); 2480 tty->cr(); 2481 } 2482 2483 ~PrintRSetsClosure() { 2484 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2485 tty->print_cr("========================================"); 2486 tty->cr(); 2487 } 2488 }; 2489 2490 void G1CollectedHeap::print_cset_rsets() { 2491 PrintRSetsClosure cl("Printing CSet RSets"); 2492 collection_set_iterate_all(&cl); 2493 } 2494 2495 void G1CollectedHeap::print_all_rsets() { 2496 PrintRSetsClosure cl("Printing All RSets");; 2497 heap_region_iterate(&cl); 2498 } 2499 #endif // PRODUCT 2500 2501 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2502 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2503 } 2504 2505 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2506 2507 size_t eden_used_bytes = _eden.used_bytes(); 2508 size_t survivor_used_bytes = _survivor.used_bytes(); 2509 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2510 2511 size_t eden_capacity_bytes = 2512 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2513 2514 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2515 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2516 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2517 } 2518 2519 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2520 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2521 stats->unused(), stats->used(), stats->region_end_waste(), 2522 stats->regions_filled(), stats->direct_allocated(), 2523 stats->failure_used(), stats->failure_waste()); 2524 } 2525 2526 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2527 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2528 gc_tracer->report_gc_heap_summary(when, heap_summary); 2529 2530 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2531 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2532 } 2533 2534 G1CollectedHeap* G1CollectedHeap::heap() { 2535 CollectedHeap* heap = Universe::heap(); 2536 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2537 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2538 return (G1CollectedHeap*)heap; 2539 } 2540 2541 void G1CollectedHeap::gc_prologue(bool full) { 2542 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2543 2544 // This summary needs to be printed before incrementing total collections. 2545 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2546 2547 // Update common counters. 2548 increment_total_collections(full /* full gc */); 2549 if (full || collector_state()->in_initial_mark_gc()) { 2550 increment_old_marking_cycles_started(); 2551 } 2552 2553 // Fill TLAB's and such 2554 double start = os::elapsedTime(); 2555 ensure_parsability(true); 2556 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2557 } 2558 2559 void G1CollectedHeap::gc_epilogue(bool full) { 2560 // Update common counters. 2561 if (full) { 2562 // Update the number of full collections that have been completed. 2563 increment_old_marking_cycles_completed(false /* concurrent */); 2564 } 2565 2566 // We are at the end of the GC. Total collections has already been increased. 2567 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2568 2569 // FIXME: what is this about? 2570 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2571 // is set. 2572 #if COMPILER2_OR_JVMCI 2573 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2574 #endif 2575 2576 double start = os::elapsedTime(); 2577 resize_all_tlabs(); 2578 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2579 2580 MemoryService::track_memory_usage(); 2581 // We have just completed a GC. Update the soft reference 2582 // policy with the new heap occupancy 2583 Universe::update_heap_info_at_gc(); 2584 } 2585 2586 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2587 uint gc_count_before, 2588 bool* succeeded, 2589 GCCause::Cause gc_cause) { 2590 assert_heap_not_locked_and_not_at_safepoint(); 2591 VM_G1CollectForAllocation op(word_size, 2592 gc_count_before, 2593 gc_cause, 2594 false, /* should_initiate_conc_mark */ 2595 policy()->max_pause_time_ms()); 2596 VMThread::execute(&op); 2597 2598 HeapWord* result = op.result(); 2599 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2600 assert(result == NULL || ret_succeeded, 2601 "the result should be NULL if the VM did not succeed"); 2602 *succeeded = ret_succeeded; 2603 2604 assert_heap_not_locked(); 2605 return result; 2606 } 2607 2608 void G1CollectedHeap::do_concurrent_mark() { 2609 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2610 if (!_cm_thread->in_progress()) { 2611 _cm_thread->set_started(); 2612 CGC_lock->notify(); 2613 } 2614 } 2615 2616 size_t G1CollectedHeap::pending_card_num() { 2617 struct CountCardsClosure : public ThreadClosure { 2618 size_t _cards; 2619 CountCardsClosure() : _cards(0) {} 2620 virtual void do_thread(Thread* t) { 2621 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2622 } 2623 } count_from_threads; 2624 Threads::threads_do(&count_from_threads); 2625 2626 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2627 dcqs.verify_num_cards(); 2628 2629 return dcqs.num_cards() + count_from_threads._cards; 2630 } 2631 2632 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2633 // We don't nominate objects with many remembered set entries, on 2634 // the assumption that such objects are likely still live. 2635 HeapRegionRemSet* rem_set = r->rem_set(); 2636 2637 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2638 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2639 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2640 } 2641 2642 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2643 private: 2644 size_t _total_humongous; 2645 size_t _candidate_humongous; 2646 2647 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2648 assert(region->is_starts_humongous(), "Must start a humongous object"); 2649 2650 oop obj = oop(region->bottom()); 2651 2652 // Dead objects cannot be eager reclaim candidates. Due to class 2653 // unloading it is unsafe to query their classes so we return early. 2654 if (g1h->is_obj_dead(obj, region)) { 2655 return false; 2656 } 2657 2658 // If we do not have a complete remembered set for the region, then we can 2659 // not be sure that we have all references to it. 2660 if (!region->rem_set()->is_complete()) { 2661 return false; 2662 } 2663 // Candidate selection must satisfy the following constraints 2664 // while concurrent marking is in progress: 2665 // 2666 // * In order to maintain SATB invariants, an object must not be 2667 // reclaimed if it was allocated before the start of marking and 2668 // has not had its references scanned. Such an object must have 2669 // its references (including type metadata) scanned to ensure no 2670 // live objects are missed by the marking process. Objects 2671 // allocated after the start of concurrent marking don't need to 2672 // be scanned. 2673 // 2674 // * An object must not be reclaimed if it is on the concurrent 2675 // mark stack. Objects allocated after the start of concurrent 2676 // marking are never pushed on the mark stack. 2677 // 2678 // Nominating only objects allocated after the start of concurrent 2679 // marking is sufficient to meet both constraints. This may miss 2680 // some objects that satisfy the constraints, but the marking data 2681 // structures don't support efficiently performing the needed 2682 // additional tests or scrubbing of the mark stack. 2683 // 2684 // However, we presently only nominate is_typeArray() objects. 2685 // A humongous object containing references induces remembered 2686 // set entries on other regions. In order to reclaim such an 2687 // object, those remembered sets would need to be cleaned up. 2688 // 2689 // We also treat is_typeArray() objects specially, allowing them 2690 // to be reclaimed even if allocated before the start of 2691 // concurrent mark. For this we rely on mark stack insertion to 2692 // exclude is_typeArray() objects, preventing reclaiming an object 2693 // that is in the mark stack. We also rely on the metadata for 2694 // such objects to be built-in and so ensured to be kept live. 2695 // Frequent allocation and drop of large binary blobs is an 2696 // important use case for eager reclaim, and this special handling 2697 // may reduce needed headroom. 2698 2699 return obj->is_typeArray() && 2700 g1h->is_potential_eager_reclaim_candidate(region); 2701 } 2702 2703 public: 2704 RegisterRegionsWithRegionAttrTableClosure() 2705 : _total_humongous(0), 2706 _candidate_humongous(0) { 2707 } 2708 2709 virtual bool do_heap_region(HeapRegion* r) { 2710 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2711 2712 if (!r->is_starts_humongous()) { 2713 g1h->register_region_with_region_attr(r); 2714 return false; 2715 } 2716 2717 bool is_candidate = humongous_region_is_candidate(g1h, r); 2718 uint rindex = r->hrm_index(); 2719 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2720 if (is_candidate) { 2721 g1h->register_humongous_region_with_region_attr(rindex); 2722 _candidate_humongous++; 2723 // We will later handle the remembered sets of these regions. 2724 } else { 2725 g1h->register_region_with_region_attr(r); 2726 } 2727 _total_humongous++; 2728 2729 return false; 2730 } 2731 2732 size_t total_humongous() const { return _total_humongous; } 2733 size_t candidate_humongous() const { return _candidate_humongous; } 2734 }; 2735 2736 void G1CollectedHeap::register_regions_with_region_attr() { 2737 Ticks start = Ticks::now(); 2738 2739 RegisterRegionsWithRegionAttrTableClosure cl; 2740 heap_region_iterate(&cl); 2741 2742 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2743 cl.total_humongous(), 2744 cl.candidate_humongous()); 2745 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2746 } 2747 2748 #ifndef PRODUCT 2749 void G1CollectedHeap::verify_region_attr_remset_update() { 2750 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2751 public: 2752 virtual bool do_heap_region(HeapRegion* r) { 2753 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2754 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2755 assert(r->rem_set()->is_tracked() == needs_remset_update, 2756 "Region %u remset tracking status (%s) different to region attribute (%s)", 2757 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2758 return false; 2759 } 2760 } cl; 2761 heap_region_iterate(&cl); 2762 } 2763 #endif 2764 2765 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2766 public: 2767 bool do_heap_region(HeapRegion* hr) { 2768 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2769 hr->verify_rem_set(); 2770 } 2771 return false; 2772 } 2773 }; 2774 2775 uint G1CollectedHeap::num_task_queues() const { 2776 return _task_queues->size(); 2777 } 2778 2779 #if TASKQUEUE_STATS 2780 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2781 st->print_raw_cr("GC Task Stats"); 2782 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2783 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2784 } 2785 2786 void G1CollectedHeap::print_taskqueue_stats() const { 2787 if (!log_is_enabled(Trace, gc, task, stats)) { 2788 return; 2789 } 2790 Log(gc, task, stats) log; 2791 ResourceMark rm; 2792 LogStream ls(log.trace()); 2793 outputStream* st = &ls; 2794 2795 print_taskqueue_stats_hdr(st); 2796 2797 TaskQueueStats totals; 2798 const uint n = num_task_queues(); 2799 for (uint i = 0; i < n; ++i) { 2800 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2801 totals += task_queue(i)->stats; 2802 } 2803 st->print_raw("tot "); totals.print(st); st->cr(); 2804 2805 DEBUG_ONLY(totals.verify()); 2806 } 2807 2808 void G1CollectedHeap::reset_taskqueue_stats() { 2809 const uint n = num_task_queues(); 2810 for (uint i = 0; i < n; ++i) { 2811 task_queue(i)->stats.reset(); 2812 } 2813 } 2814 #endif // TASKQUEUE_STATS 2815 2816 void G1CollectedHeap::wait_for_root_region_scanning() { 2817 double scan_wait_start = os::elapsedTime(); 2818 // We have to wait until the CM threads finish scanning the 2819 // root regions as it's the only way to ensure that all the 2820 // objects on them have been correctly scanned before we start 2821 // moving them during the GC. 2822 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2823 double wait_time_ms = 0.0; 2824 if (waited) { 2825 double scan_wait_end = os::elapsedTime(); 2826 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2827 } 2828 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2829 } 2830 2831 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2832 private: 2833 G1HRPrinter* _hr_printer; 2834 public: 2835 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2836 2837 virtual bool do_heap_region(HeapRegion* r) { 2838 _hr_printer->cset(r); 2839 return false; 2840 } 2841 }; 2842 2843 void G1CollectedHeap::start_new_collection_set() { 2844 double start = os::elapsedTime(); 2845 2846 collection_set()->start_incremental_building(); 2847 2848 clear_region_attr(); 2849 2850 guarantee(_eden.length() == 0, "eden should have been cleared"); 2851 policy()->transfer_survivors_to_cset(survivor()); 2852 2853 // We redo the verification but now wrt to the new CSet which 2854 // has just got initialized after the previous CSet was freed. 2855 _cm->verify_no_collection_set_oops(); 2856 2857 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2858 } 2859 2860 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2861 2862 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2863 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2864 collection_set()->optional_region_length()); 2865 2866 _cm->verify_no_collection_set_oops(); 2867 2868 if (_hr_printer.is_active()) { 2869 G1PrintCollectionSetClosure cl(&_hr_printer); 2870 _collection_set.iterate(&cl); 2871 _collection_set.iterate_optional(&cl); 2872 } 2873 } 2874 2875 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2876 if (collector_state()->in_initial_mark_gc()) { 2877 return G1HeapVerifier::G1VerifyConcurrentStart; 2878 } else if (collector_state()->in_young_only_phase()) { 2879 return G1HeapVerifier::G1VerifyYoungNormal; 2880 } else { 2881 return G1HeapVerifier::G1VerifyMixed; 2882 } 2883 } 2884 2885 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2886 if (VerifyRememberedSets) { 2887 log_info(gc, verify)("[Verifying RemSets before GC]"); 2888 VerifyRegionRemSetClosure v_cl; 2889 heap_region_iterate(&v_cl); 2890 } 2891 _verifier->verify_before_gc(type); 2892 _verifier->check_bitmaps("GC Start"); 2893 } 2894 2895 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2896 if (VerifyRememberedSets) { 2897 log_info(gc, verify)("[Verifying RemSets after GC]"); 2898 VerifyRegionRemSetClosure v_cl; 2899 heap_region_iterate(&v_cl); 2900 } 2901 _verifier->verify_after_gc(type); 2902 _verifier->check_bitmaps("GC End"); 2903 } 2904 2905 void G1CollectedHeap::expand_heap_after_young_collection(){ 2906 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2907 if (expand_bytes > 0) { 2908 // No need for an ergo logging here, 2909 // expansion_amount() does this when it returns a value > 0. 2910 double expand_ms; 2911 if (!expand(expand_bytes, _workers, &expand_ms)) { 2912 // We failed to expand the heap. Cannot do anything about it. 2913 } 2914 phase_times()->record_expand_heap_time(expand_ms); 2915 } 2916 } 2917 2918 const char* G1CollectedHeap::young_gc_name() const { 2919 if (collector_state()->in_initial_mark_gc()) { 2920 return "Pause Young (Concurrent Start)"; 2921 } else if (collector_state()->in_young_only_phase()) { 2922 if (collector_state()->in_young_gc_before_mixed()) { 2923 return "Pause Young (Prepare Mixed)"; 2924 } else { 2925 return "Pause Young (Normal)"; 2926 } 2927 } else { 2928 return "Pause Young (Mixed)"; 2929 } 2930 } 2931 2932 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2933 assert_at_safepoint_on_vm_thread(); 2934 guarantee(!is_gc_active(), "collection is not reentrant"); 2935 2936 if (GCLocker::check_active_before_gc()) { 2937 return false; 2938 } 2939 2940 GCIdMark gc_id_mark; 2941 2942 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2943 ResourceMark rm; 2944 2945 policy()->note_gc_start(); 2946 2947 _gc_timer_stw->register_gc_start(); 2948 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2949 2950 wait_for_root_region_scanning(); 2951 2952 print_heap_before_gc(); 2953 print_heap_regions(); 2954 trace_heap_before_gc(_gc_tracer_stw); 2955 2956 _verifier->verify_region_sets_optional(); 2957 _verifier->verify_dirty_young_regions(); 2958 2959 // We should not be doing initial mark unless the conc mark thread is running 2960 if (!_cm_thread->should_terminate()) { 2961 // This call will decide whether this pause is an initial-mark 2962 // pause. If it is, in_initial_mark_gc() will return true 2963 // for the duration of this pause. 2964 policy()->decide_on_conc_mark_initiation(); 2965 } 2966 2967 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2968 assert(!collector_state()->in_initial_mark_gc() || 2969 collector_state()->in_young_only_phase(), "sanity"); 2970 // We also do not allow mixed GCs during marking. 2971 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2972 2973 // Record whether this pause is an initial mark. When the current 2974 // thread has completed its logging output and it's safe to signal 2975 // the CM thread, the flag's value in the policy has been reset. 2976 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2977 if (should_start_conc_mark) { 2978 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2979 } 2980 2981 // Inner scope for scope based logging, timers, and stats collection 2982 { 2983 G1EvacuationInfo evacuation_info; 2984 2985 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2986 2987 GCTraceCPUTime tcpu; 2988 2989 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 2990 2991 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2992 workers()->active_workers(), 2993 Threads::number_of_non_daemon_threads()); 2994 active_workers = workers()->update_active_workers(active_workers); 2995 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2996 2997 G1MonitoringScope ms(g1mm(), 2998 false /* full_gc */, 2999 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3000 3001 G1HeapTransition heap_transition(this); 3002 size_t heap_used_bytes_before_gc = used(); 3003 3004 { 3005 IsGCActiveMark x; 3006 3007 gc_prologue(false); 3008 3009 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3010 verify_before_young_collection(verify_type); 3011 3012 { 3013 // The elapsed time induced by the start time below deliberately elides 3014 // the possible verification above. 3015 double sample_start_time_sec = os::elapsedTime(); 3016 3017 // Please see comment in g1CollectedHeap.hpp and 3018 // G1CollectedHeap::ref_processing_init() to see how 3019 // reference processing currently works in G1. 3020 _ref_processor_stw->enable_discovery(); 3021 3022 // We want to temporarily turn off discovery by the 3023 // CM ref processor, if necessary, and turn it back on 3024 // on again later if we do. Using a scoped 3025 // NoRefDiscovery object will do this. 3026 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3027 3028 policy()->record_collection_pause_start(sample_start_time_sec); 3029 3030 // Forget the current allocation region (we might even choose it to be part 3031 // of the collection set!). 3032 _allocator->release_mutator_alloc_regions(); 3033 3034 calculate_collection_set(evacuation_info, target_pause_time_ms); 3035 3036 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3037 G1ParScanThreadStateSet per_thread_states(this, 3038 &rdcqs, 3039 workers()->active_workers(), 3040 collection_set()->young_region_length(), 3041 collection_set()->optional_region_length()); 3042 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3043 3044 // Actually do the work... 3045 evacuate_initial_collection_set(&per_thread_states); 3046 3047 if (_collection_set.optional_region_length() != 0) { 3048 evacuate_optional_collection_set(&per_thread_states); 3049 } 3050 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3051 3052 start_new_collection_set(); 3053 3054 _survivor_evac_stats.adjust_desired_plab_sz(); 3055 _old_evac_stats.adjust_desired_plab_sz(); 3056 3057 if (should_start_conc_mark) { 3058 // We have to do this before we notify the CM threads that 3059 // they can start working to make sure that all the 3060 // appropriate initialization is done on the CM object. 3061 concurrent_mark()->post_initial_mark(); 3062 // Note that we don't actually trigger the CM thread at 3063 // this point. We do that later when we're sure that 3064 // the current thread has completed its logging output. 3065 } 3066 3067 allocate_dummy_regions(); 3068 3069 _allocator->init_mutator_alloc_regions(); 3070 3071 expand_heap_after_young_collection(); 3072 3073 double sample_end_time_sec = os::elapsedTime(); 3074 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3075 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc); 3076 } 3077 3078 verify_after_young_collection(verify_type); 3079 3080 #ifdef TRACESPINNING 3081 ParallelTaskTerminator::print_termination_counts(); 3082 #endif 3083 3084 gc_epilogue(false); 3085 } 3086 3087 // Print the remainder of the GC log output. 3088 if (evacuation_failed()) { 3089 log_info(gc)("To-space exhausted"); 3090 } 3091 3092 policy()->print_phases(); 3093 heap_transition.print(); 3094 3095 _hrm->verify_optional(); 3096 _verifier->verify_region_sets_optional(); 3097 3098 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3099 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3100 3101 print_heap_after_gc(); 3102 print_heap_regions(); 3103 trace_heap_after_gc(_gc_tracer_stw); 3104 3105 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3106 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3107 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3108 // before any GC notifications are raised. 3109 g1mm()->update_sizes(); 3110 3111 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3112 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3113 _gc_timer_stw->register_gc_end(); 3114 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3115 } 3116 // It should now be safe to tell the concurrent mark thread to start 3117 // without its logging output interfering with the logging output 3118 // that came from the pause. 3119 3120 if (should_start_conc_mark) { 3121 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3122 // thread(s) could be running concurrently with us. Make sure that anything 3123 // after this point does not assume that we are the only GC thread running. 3124 // Note: of course, the actual marking work will not start until the safepoint 3125 // itself is released in SuspendibleThreadSet::desynchronize(). 3126 do_concurrent_mark(); 3127 } 3128 3129 return true; 3130 } 3131 3132 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3133 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3134 workers()->run_task(&rsfp_task); 3135 } 3136 3137 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3138 double remove_self_forwards_start = os::elapsedTime(); 3139 3140 remove_self_forwarding_pointers(rdcqs); 3141 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3142 _preserved_marks_set.restore(&task_executor); 3143 3144 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3145 } 3146 3147 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3148 if (!_evacuation_failed) { 3149 _evacuation_failed = true; 3150 } 3151 3152 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3153 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3154 } 3155 3156 bool G1ParEvacuateFollowersClosure::offer_termination() { 3157 EventGCPhaseParallel event; 3158 G1ParScanThreadState* const pss = par_scan_state(); 3159 start_term_time(); 3160 const bool res = terminator()->offer_termination(); 3161 end_term_time(); 3162 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3163 return res; 3164 } 3165 3166 void G1ParEvacuateFollowersClosure::do_void() { 3167 EventGCPhaseParallel event; 3168 G1ParScanThreadState* const pss = par_scan_state(); 3169 pss->trim_queue(); 3170 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3171 do { 3172 EventGCPhaseParallel event; 3173 pss->steal_and_trim_queue(queues()); 3174 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3175 } while (!offer_termination()); 3176 } 3177 3178 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3179 bool class_unloading_occurred) { 3180 uint num_workers = workers()->active_workers(); 3181 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3182 workers()->run_task(&unlink_task); 3183 } 3184 3185 // Clean string dedup data structures. 3186 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3187 // record the durations of the phases. Hence the almost-copy. 3188 class G1StringDedupCleaningTask : public AbstractGangTask { 3189 BoolObjectClosure* _is_alive; 3190 OopClosure* _keep_alive; 3191 G1GCPhaseTimes* _phase_times; 3192 3193 public: 3194 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3195 OopClosure* keep_alive, 3196 G1GCPhaseTimes* phase_times) : 3197 AbstractGangTask("Partial Cleaning Task"), 3198 _is_alive(is_alive), 3199 _keep_alive(keep_alive), 3200 _phase_times(phase_times) 3201 { 3202 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3203 StringDedup::gc_prologue(true); 3204 } 3205 3206 ~G1StringDedupCleaningTask() { 3207 StringDedup::gc_epilogue(); 3208 } 3209 3210 void work(uint worker_id) { 3211 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3212 { 3213 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3214 StringDedupQueue::unlink_or_oops_do(&cl); 3215 } 3216 { 3217 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3218 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3219 } 3220 } 3221 }; 3222 3223 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3224 OopClosure* keep_alive, 3225 G1GCPhaseTimes* phase_times) { 3226 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3227 workers()->run_task(&cl); 3228 } 3229 3230 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3231 private: 3232 G1RedirtyCardsQueueSet* _qset; 3233 G1CollectedHeap* _g1h; 3234 BufferNode* volatile _nodes; 3235 3236 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3237 size_t buffer_size = _qset->buffer_size(); 3238 BufferNode* next = Atomic::load(&_nodes); 3239 while (next != NULL) { 3240 BufferNode* node = next; 3241 next = Atomic::cmpxchg(node->next(), &_nodes, node); 3242 if (next == node) { 3243 cl->apply_to_buffer(node, buffer_size, worker_id); 3244 next = node->next(); 3245 } 3246 } 3247 } 3248 3249 public: 3250 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3251 AbstractGangTask("Redirty Cards"), 3252 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3253 3254 virtual void work(uint worker_id) { 3255 G1GCPhaseTimes* p = _g1h->phase_times(); 3256 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3257 3258 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3259 par_apply(&cl, worker_id); 3260 3261 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3262 } 3263 }; 3264 3265 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3266 double redirty_logged_cards_start = os::elapsedTime(); 3267 3268 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3269 workers()->run_task(&redirty_task); 3270 3271 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3272 dcq.merge_bufferlists(rdcqs); 3273 3274 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3275 } 3276 3277 // Weak Reference Processing support 3278 3279 bool G1STWIsAliveClosure::do_object_b(oop p) { 3280 // An object is reachable if it is outside the collection set, 3281 // or is inside and copied. 3282 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3283 } 3284 3285 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3286 assert(obj != NULL, "must not be NULL"); 3287 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3288 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3289 // may falsely indicate that this is not the case here: however the collection set only 3290 // contains old regions when concurrent mark is not running. 3291 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3292 } 3293 3294 // Non Copying Keep Alive closure 3295 class G1KeepAliveClosure: public OopClosure { 3296 G1CollectedHeap*_g1h; 3297 public: 3298 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3299 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3300 void do_oop(oop* p) { 3301 oop obj = *p; 3302 assert(obj != NULL, "the caller should have filtered out NULL values"); 3303 3304 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3305 if (!region_attr.is_in_cset_or_humongous()) { 3306 return; 3307 } 3308 if (region_attr.is_in_cset()) { 3309 assert( obj->is_forwarded(), "invariant" ); 3310 *p = obj->forwardee(); 3311 } else { 3312 assert(!obj->is_forwarded(), "invariant" ); 3313 assert(region_attr.is_humongous(), 3314 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3315 _g1h->set_humongous_is_live(obj); 3316 } 3317 } 3318 }; 3319 3320 // Copying Keep Alive closure - can be called from both 3321 // serial and parallel code as long as different worker 3322 // threads utilize different G1ParScanThreadState instances 3323 // and different queues. 3324 3325 class G1CopyingKeepAliveClosure: public OopClosure { 3326 G1CollectedHeap* _g1h; 3327 G1ParScanThreadState* _par_scan_state; 3328 3329 public: 3330 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3331 G1ParScanThreadState* pss): 3332 _g1h(g1h), 3333 _par_scan_state(pss) 3334 {} 3335 3336 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3337 virtual void do_oop( oop* p) { do_oop_work(p); } 3338 3339 template <class T> void do_oop_work(T* p) { 3340 oop obj = RawAccess<>::oop_load(p); 3341 3342 if (_g1h->is_in_cset_or_humongous(obj)) { 3343 // If the referent object has been forwarded (either copied 3344 // to a new location or to itself in the event of an 3345 // evacuation failure) then we need to update the reference 3346 // field and, if both reference and referent are in the G1 3347 // heap, update the RSet for the referent. 3348 // 3349 // If the referent has not been forwarded then we have to keep 3350 // it alive by policy. Therefore we have copy the referent. 3351 // 3352 // When the queue is drained (after each phase of reference processing) 3353 // the object and it's followers will be copied, the reference field set 3354 // to point to the new location, and the RSet updated. 3355 _par_scan_state->push_on_queue(p); 3356 } 3357 } 3358 }; 3359 3360 // Serial drain queue closure. Called as the 'complete_gc' 3361 // closure for each discovered list in some of the 3362 // reference processing phases. 3363 3364 class G1STWDrainQueueClosure: public VoidClosure { 3365 protected: 3366 G1CollectedHeap* _g1h; 3367 G1ParScanThreadState* _par_scan_state; 3368 3369 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3370 3371 public: 3372 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3373 _g1h(g1h), 3374 _par_scan_state(pss) 3375 { } 3376 3377 void do_void() { 3378 G1ParScanThreadState* const pss = par_scan_state(); 3379 pss->trim_queue(); 3380 } 3381 }; 3382 3383 // Parallel Reference Processing closures 3384 3385 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3386 // processing during G1 evacuation pauses. 3387 3388 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3389 private: 3390 G1CollectedHeap* _g1h; 3391 G1ParScanThreadStateSet* _pss; 3392 RefToScanQueueSet* _queues; 3393 WorkGang* _workers; 3394 3395 public: 3396 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3397 G1ParScanThreadStateSet* per_thread_states, 3398 WorkGang* workers, 3399 RefToScanQueueSet *task_queues) : 3400 _g1h(g1h), 3401 _pss(per_thread_states), 3402 _queues(task_queues), 3403 _workers(workers) 3404 { 3405 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3406 } 3407 3408 // Executes the given task using concurrent marking worker threads. 3409 virtual void execute(ProcessTask& task, uint ergo_workers); 3410 }; 3411 3412 // Gang task for possibly parallel reference processing 3413 3414 class G1STWRefProcTaskProxy: public AbstractGangTask { 3415 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3416 ProcessTask& _proc_task; 3417 G1CollectedHeap* _g1h; 3418 G1ParScanThreadStateSet* _pss; 3419 RefToScanQueueSet* _task_queues; 3420 ParallelTaskTerminator* _terminator; 3421 3422 public: 3423 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3424 G1CollectedHeap* g1h, 3425 G1ParScanThreadStateSet* per_thread_states, 3426 RefToScanQueueSet *task_queues, 3427 ParallelTaskTerminator* terminator) : 3428 AbstractGangTask("Process reference objects in parallel"), 3429 _proc_task(proc_task), 3430 _g1h(g1h), 3431 _pss(per_thread_states), 3432 _task_queues(task_queues), 3433 _terminator(terminator) 3434 {} 3435 3436 virtual void work(uint worker_id) { 3437 // The reference processing task executed by a single worker. 3438 ResourceMark rm; 3439 HandleMark hm; 3440 3441 G1STWIsAliveClosure is_alive(_g1h); 3442 3443 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3444 pss->set_ref_discoverer(NULL); 3445 3446 // Keep alive closure. 3447 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3448 3449 // Complete GC closure 3450 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3451 3452 // Call the reference processing task's work routine. 3453 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3454 3455 // Note we cannot assert that the refs array is empty here as not all 3456 // of the processing tasks (specifically phase2 - pp2_work) execute 3457 // the complete_gc closure (which ordinarily would drain the queue) so 3458 // the queue may not be empty. 3459 } 3460 }; 3461 3462 // Driver routine for parallel reference processing. 3463 // Creates an instance of the ref processing gang 3464 // task and has the worker threads execute it. 3465 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3466 assert(_workers != NULL, "Need parallel worker threads."); 3467 3468 assert(_workers->active_workers() >= ergo_workers, 3469 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3470 ergo_workers, _workers->active_workers()); 3471 TaskTerminator terminator(ergo_workers, _queues); 3472 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3473 3474 _workers->run_task(&proc_task_proxy, ergo_workers); 3475 } 3476 3477 // End of weak reference support closures 3478 3479 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3480 double ref_proc_start = os::elapsedTime(); 3481 3482 ReferenceProcessor* rp = _ref_processor_stw; 3483 assert(rp->discovery_enabled(), "should have been enabled"); 3484 3485 // Closure to test whether a referent is alive. 3486 G1STWIsAliveClosure is_alive(this); 3487 3488 // Even when parallel reference processing is enabled, the processing 3489 // of JNI refs is serial and performed serially by the current thread 3490 // rather than by a worker. The following PSS will be used for processing 3491 // JNI refs. 3492 3493 // Use only a single queue for this PSS. 3494 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3495 pss->set_ref_discoverer(NULL); 3496 assert(pss->queue_is_empty(), "pre-condition"); 3497 3498 // Keep alive closure. 3499 G1CopyingKeepAliveClosure keep_alive(this, pss); 3500 3501 // Serial Complete GC closure 3502 G1STWDrainQueueClosure drain_queue(this, pss); 3503 3504 // Setup the soft refs policy... 3505 rp->setup_policy(false); 3506 3507 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3508 3509 ReferenceProcessorStats stats; 3510 if (!rp->processing_is_mt()) { 3511 // Serial reference processing... 3512 stats = rp->process_discovered_references(&is_alive, 3513 &keep_alive, 3514 &drain_queue, 3515 NULL, 3516 pt); 3517 } else { 3518 uint no_of_gc_workers = workers()->active_workers(); 3519 3520 // Parallel reference processing 3521 assert(no_of_gc_workers <= rp->max_num_queues(), 3522 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3523 no_of_gc_workers, rp->max_num_queues()); 3524 3525 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3526 stats = rp->process_discovered_references(&is_alive, 3527 &keep_alive, 3528 &drain_queue, 3529 &par_task_executor, 3530 pt); 3531 } 3532 3533 _gc_tracer_stw->report_gc_reference_stats(stats); 3534 3535 // We have completed copying any necessary live referent objects. 3536 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3537 3538 make_pending_list_reachable(); 3539 3540 assert(!rp->discovery_enabled(), "Postcondition"); 3541 rp->verify_no_references_recorded(); 3542 3543 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3544 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3545 } 3546 3547 void G1CollectedHeap::make_pending_list_reachable() { 3548 if (collector_state()->in_initial_mark_gc()) { 3549 oop pll_head = Universe::reference_pending_list(); 3550 if (pll_head != NULL) { 3551 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3552 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3553 } 3554 } 3555 } 3556 3557 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3558 double merge_pss_time_start = os::elapsedTime(); 3559 per_thread_states->flush(); 3560 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3561 } 3562 3563 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3564 _expand_heap_after_alloc_failure = true; 3565 _evacuation_failed = false; 3566 3567 // Disable the hot card cache. 3568 _hot_card_cache->reset_hot_cache_claimed_index(); 3569 _hot_card_cache->set_use_cache(false); 3570 3571 // Initialize the GC alloc regions. 3572 _allocator->init_gc_alloc_regions(evacuation_info); 3573 3574 { 3575 Ticks start = Ticks::now(); 3576 rem_set()->prepare_for_scan_heap_roots(); 3577 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3578 } 3579 3580 register_regions_with_region_attr(); 3581 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3582 3583 _preserved_marks_set.assert_empty(); 3584 3585 #if COMPILER2_OR_JVMCI 3586 DerivedPointerTable::clear(); 3587 #endif 3588 3589 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3590 if (collector_state()->in_initial_mark_gc()) { 3591 concurrent_mark()->pre_initial_mark(); 3592 3593 double start_clear_claimed_marks = os::elapsedTime(); 3594 3595 ClassLoaderDataGraph::clear_claimed_marks(); 3596 3597 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3598 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3599 } 3600 3601 // Should G1EvacuationFailureALot be in effect for this GC? 3602 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3603 } 3604 3605 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3606 protected: 3607 G1CollectedHeap* _g1h; 3608 G1ParScanThreadStateSet* _per_thread_states; 3609 RefToScanQueueSet* _task_queues; 3610 TaskTerminator _terminator; 3611 uint _num_workers; 3612 3613 void evacuate_live_objects(G1ParScanThreadState* pss, 3614 uint worker_id, 3615 G1GCPhaseTimes::GCParPhases objcopy_phase, 3616 G1GCPhaseTimes::GCParPhases termination_phase) { 3617 G1GCPhaseTimes* p = _g1h->phase_times(); 3618 3619 Ticks start = Ticks::now(); 3620 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase); 3621 cl.do_void(); 3622 3623 assert(pss->queue_is_empty(), "should be empty"); 3624 3625 Tickspan evac_time = (Ticks::now() - start); 3626 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3627 3628 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste); 3629 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste); 3630 3631 if (termination_phase == G1GCPhaseTimes::Termination) { 3632 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3633 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3634 } else { 3635 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3636 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3637 } 3638 } 3639 3640 virtual void start_work(uint worker_id) { } 3641 3642 virtual void end_work(uint worker_id) { } 3643 3644 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3645 3646 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3647 3648 public: 3649 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3650 AbstractGangTask(name), 3651 _g1h(G1CollectedHeap::heap()), 3652 _per_thread_states(per_thread_states), 3653 _task_queues(task_queues), 3654 _terminator(num_workers, _task_queues), 3655 _num_workers(num_workers) 3656 { } 3657 3658 void work(uint worker_id) { 3659 start_work(worker_id); 3660 3661 { 3662 ResourceMark rm; 3663 HandleMark hm; 3664 3665 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3666 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3667 3668 scan_roots(pss, worker_id); 3669 evacuate_live_objects(pss, worker_id); 3670 } 3671 3672 end_work(worker_id); 3673 } 3674 }; 3675 3676 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3677 G1RootProcessor* _root_processor; 3678 3679 void verify_trim_ticks(G1ParScanThreadState* pss, const char* location) { 3680 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()); 3681 } 3682 3683 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3684 _root_processor->evacuate_roots(pss, worker_id); 3685 verify_trim_ticks(pss, "roots"); 3686 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3687 verify_trim_ticks(pss, "heap roots"); 3688 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3689 verify_trim_ticks(pss, "scan cset"); 3690 } 3691 3692 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3693 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3694 verify_trim_ticks(pss, "evac live"); 3695 } 3696 3697 void start_work(uint worker_id) { 3698 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3699 } 3700 3701 void end_work(uint worker_id) { 3702 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3703 } 3704 3705 public: 3706 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3707 G1ParScanThreadStateSet* per_thread_states, 3708 RefToScanQueueSet* task_queues, 3709 G1RootProcessor* root_processor, 3710 uint num_workers) : 3711 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3712 _root_processor(root_processor) 3713 { } 3714 }; 3715 3716 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3717 G1GCPhaseTimes* p = phase_times(); 3718 3719 { 3720 Ticks start = Ticks::now(); 3721 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3722 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3723 } 3724 3725 Tickspan task_time; 3726 const uint num_workers = workers()->active_workers(); 3727 3728 Ticks start_processing = Ticks::now(); 3729 { 3730 G1RootProcessor root_processor(this, num_workers); 3731 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3732 task_time = run_task(&g1_par_task); 3733 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3734 // To extract its code root fixup time we measure total time of this scope and 3735 // subtract from the time the WorkGang task took. 3736 } 3737 Tickspan total_processing = Ticks::now() - start_processing; 3738 3739 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3740 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3741 } 3742 3743 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3744 3745 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3746 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3747 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3748 } 3749 3750 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3751 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3752 } 3753 3754 public: 3755 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3756 RefToScanQueueSet* queues, 3757 uint num_workers) : 3758 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3759 } 3760 }; 3761 3762 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3763 class G1MarkScope : public MarkScope { }; 3764 3765 Tickspan task_time; 3766 3767 Ticks start_processing = Ticks::now(); 3768 { 3769 G1MarkScope code_mark_scope; 3770 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3771 task_time = run_task(&task); 3772 // See comment in evacuate_collection_set() for the reason of the scope. 3773 } 3774 Tickspan total_processing = Ticks::now() - start_processing; 3775 3776 G1GCPhaseTimes* p = phase_times(); 3777 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3778 } 3779 3780 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3781 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3782 3783 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3784 3785 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3786 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3787 3788 if (time_left_ms < 0 || 3789 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3790 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3791 _collection_set.optional_region_length(), time_left_ms); 3792 break; 3793 } 3794 3795 { 3796 Ticks start = Ticks::now(); 3797 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3798 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3799 } 3800 3801 { 3802 Ticks start = Ticks::now(); 3803 evacuate_next_optional_regions(per_thread_states); 3804 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3805 } 3806 } 3807 3808 _collection_set.abandon_optional_collection_set(per_thread_states); 3809 } 3810 3811 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3812 G1RedirtyCardsQueueSet* rdcqs, 3813 G1ParScanThreadStateSet* per_thread_states) { 3814 rem_set()->cleanup_after_scan_heap_roots(); 3815 3816 // Process any discovered reference objects - we have 3817 // to do this _before_ we retire the GC alloc regions 3818 // as we may have to copy some 'reachable' referent 3819 // objects (and their reachable sub-graphs) that were 3820 // not copied during the pause. 3821 process_discovered_references(per_thread_states); 3822 3823 G1STWIsAliveClosure is_alive(this); 3824 G1KeepAliveClosure keep_alive(this); 3825 3826 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3827 phase_times()->weak_phase_times()); 3828 3829 if (G1StringDedup::is_enabled()) { 3830 double string_dedup_time_ms = os::elapsedTime(); 3831 3832 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3833 3834 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3835 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3836 } 3837 3838 _allocator->release_gc_alloc_regions(evacuation_info); 3839 3840 if (evacuation_failed()) { 3841 restore_after_evac_failure(rdcqs); 3842 3843 // Reset the G1EvacuationFailureALot counters and flags 3844 NOT_PRODUCT(reset_evacuation_should_fail();) 3845 3846 double recalculate_used_start = os::elapsedTime(); 3847 set_used(recalculate_used()); 3848 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3849 3850 if (_archive_allocator != NULL) { 3851 _archive_allocator->clear_used(); 3852 } 3853 for (uint i = 0; i < ParallelGCThreads; i++) { 3854 if (_evacuation_failed_info_array[i].has_failed()) { 3855 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3856 } 3857 } 3858 } else { 3859 // The "used" of the the collection set have already been subtracted 3860 // when they were freed. Add in the bytes evacuated. 3861 increase_used(policy()->bytes_copied_during_gc()); 3862 } 3863 3864 _preserved_marks_set.assert_empty(); 3865 3866 merge_per_thread_state_info(per_thread_states); 3867 3868 // Reset and re-enable the hot card cache. 3869 // Note the counts for the cards in the regions in the 3870 // collection set are reset when the collection set is freed. 3871 _hot_card_cache->reset_hot_cache(); 3872 _hot_card_cache->set_use_cache(true); 3873 3874 purge_code_root_memory(); 3875 3876 redirty_logged_cards(rdcqs); 3877 3878 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3879 3880 eagerly_reclaim_humongous_regions(); 3881 3882 record_obj_copy_mem_stats(); 3883 3884 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3885 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3886 3887 #if COMPILER2_OR_JVMCI 3888 double start = os::elapsedTime(); 3889 DerivedPointerTable::update_pointers(); 3890 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3891 #endif 3892 policy()->print_age_table(); 3893 } 3894 3895 void G1CollectedHeap::record_obj_copy_mem_stats() { 3896 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3897 3898 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3899 create_g1_evac_summary(&_old_evac_stats)); 3900 } 3901 3902 void G1CollectedHeap::free_region(HeapRegion* hr, 3903 FreeRegionList* free_list, 3904 bool skip_remset, 3905 bool skip_hot_card_cache, 3906 bool locked) { 3907 assert(!hr->is_free(), "the region should not be free"); 3908 assert(!hr->is_empty(), "the region should not be empty"); 3909 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3910 assert(free_list != NULL, "pre-condition"); 3911 3912 if (G1VerifyBitmaps) { 3913 MemRegion mr(hr->bottom(), hr->end()); 3914 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3915 } 3916 3917 // Clear the card counts for this region. 3918 // Note: we only need to do this if the region is not young 3919 // (since we don't refine cards in young regions). 3920 if (!skip_hot_card_cache && !hr->is_young()) { 3921 _hot_card_cache->reset_card_counts(hr); 3922 } 3923 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3924 _policy->remset_tracker()->update_at_free(hr); 3925 free_list->add_ordered(hr); 3926 } 3927 3928 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3929 FreeRegionList* free_list) { 3930 assert(hr->is_humongous(), "this is only for humongous regions"); 3931 assert(free_list != NULL, "pre-condition"); 3932 hr->clear_humongous(); 3933 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3934 } 3935 3936 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3937 const uint humongous_regions_removed) { 3938 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3939 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3940 _old_set.bulk_remove(old_regions_removed); 3941 _humongous_set.bulk_remove(humongous_regions_removed); 3942 } 3943 3944 } 3945 3946 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3947 assert(list != NULL, "list can't be null"); 3948 if (!list->is_empty()) { 3949 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3950 _hrm->insert_list_into_free_list(list); 3951 } 3952 } 3953 3954 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3955 decrease_used(bytes); 3956 } 3957 3958 class G1FreeCollectionSetTask : public AbstractGangTask { 3959 private: 3960 3961 // Closure applied to all regions in the collection set to do work that needs to 3962 // be done serially in a single thread. 3963 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3964 private: 3965 G1EvacuationInfo* _evacuation_info; 3966 const size_t* _surviving_young_words; 3967 3968 // Bytes used in successfully evacuated regions before the evacuation. 3969 size_t _before_used_bytes; 3970 // Bytes used in unsucessfully evacuated regions before the evacuation 3971 size_t _after_used_bytes; 3972 3973 size_t _bytes_allocated_in_old_since_last_gc; 3974 3975 size_t _failure_used_words; 3976 size_t _failure_waste_words; 3977 3978 FreeRegionList _local_free_list; 3979 public: 3980 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3981 HeapRegionClosure(), 3982 _evacuation_info(evacuation_info), 3983 _surviving_young_words(surviving_young_words), 3984 _before_used_bytes(0), 3985 _after_used_bytes(0), 3986 _bytes_allocated_in_old_since_last_gc(0), 3987 _failure_used_words(0), 3988 _failure_waste_words(0), 3989 _local_free_list("Local Region List for CSet Freeing") { 3990 } 3991 3992 virtual bool do_heap_region(HeapRegion* r) { 3993 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3994 3995 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3996 g1h->clear_region_attr(r); 3997 3998 if (r->is_young()) { 3999 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(), 4000 "Young index %u is wrong for region %u of type %s with %u young regions", 4001 r->young_index_in_cset(), 4002 r->hrm_index(), 4003 r->get_type_str(), 4004 g1h->collection_set()->young_region_length()); 4005 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4006 r->record_surv_words_in_group(words_survived); 4007 } 4008 4009 if (!r->evacuation_failed()) { 4010 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4011 _before_used_bytes += r->used(); 4012 g1h->free_region(r, 4013 &_local_free_list, 4014 true, /* skip_remset */ 4015 true, /* skip_hot_card_cache */ 4016 true /* locked */); 4017 } else { 4018 r->uninstall_surv_rate_group(); 4019 r->clear_young_index_in_cset(); 4020 r->set_evacuation_failed(false); 4021 // When moving a young gen region to old gen, we "allocate" that whole region 4022 // there. This is in addition to any already evacuated objects. Notify the 4023 // policy about that. 4024 // Old gen regions do not cause an additional allocation: both the objects 4025 // still in the region and the ones already moved are accounted for elsewhere. 4026 if (r->is_young()) { 4027 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4028 } 4029 // The region is now considered to be old. 4030 r->set_old(); 4031 // Do some allocation statistics accounting. Regions that failed evacuation 4032 // are always made old, so there is no need to update anything in the young 4033 // gen statistics, but we need to update old gen statistics. 4034 size_t used_words = r->marked_bytes() / HeapWordSize; 4035 4036 _failure_used_words += used_words; 4037 _failure_waste_words += HeapRegion::GrainWords - used_words; 4038 4039 g1h->old_set_add(r); 4040 _after_used_bytes += r->used(); 4041 } 4042 return false; 4043 } 4044 4045 void complete_work() { 4046 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4047 4048 _evacuation_info->set_regions_freed(_local_free_list.length()); 4049 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4050 4051 g1h->prepend_to_freelist(&_local_free_list); 4052 g1h->decrement_summary_bytes(_before_used_bytes); 4053 4054 G1Policy* policy = g1h->policy(); 4055 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4056 4057 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4058 } 4059 }; 4060 4061 G1CollectionSet* _collection_set; 4062 G1SerialFreeCollectionSetClosure _cl; 4063 const size_t* _surviving_young_words; 4064 4065 size_t _rs_length; 4066 4067 volatile jint _serial_work_claim; 4068 4069 struct WorkItem { 4070 uint region_idx; 4071 bool is_young; 4072 bool evacuation_failed; 4073 4074 WorkItem(HeapRegion* r) { 4075 region_idx = r->hrm_index(); 4076 is_young = r->is_young(); 4077 evacuation_failed = r->evacuation_failed(); 4078 } 4079 }; 4080 4081 volatile size_t _parallel_work_claim; 4082 size_t _num_work_items; 4083 WorkItem* _work_items; 4084 4085 void do_serial_work() { 4086 // Need to grab the lock to be allowed to modify the old region list. 4087 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4088 _collection_set->iterate(&_cl); 4089 } 4090 4091 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4092 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4093 4094 HeapRegion* r = g1h->region_at(region_idx); 4095 assert(!g1h->is_on_master_free_list(r), "sanity"); 4096 4097 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length); 4098 4099 if (!is_young) { 4100 g1h->_hot_card_cache->reset_card_counts(r); 4101 } 4102 4103 if (!evacuation_failed) { 4104 r->rem_set()->clear_locked(); 4105 } 4106 } 4107 4108 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4109 private: 4110 size_t _cur_idx; 4111 WorkItem* _work_items; 4112 public: 4113 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4114 4115 virtual bool do_heap_region(HeapRegion* r) { 4116 _work_items[_cur_idx++] = WorkItem(r); 4117 return false; 4118 } 4119 }; 4120 4121 void prepare_work() { 4122 G1PrepareFreeCollectionSetClosure cl(_work_items); 4123 _collection_set->iterate(&cl); 4124 } 4125 4126 void complete_work() { 4127 _cl.complete_work(); 4128 4129 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4130 policy->record_max_rs_length(_rs_length); 4131 policy->cset_regions_freed(); 4132 } 4133 public: 4134 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4135 AbstractGangTask("G1 Free Collection Set"), 4136 _collection_set(collection_set), 4137 _cl(evacuation_info, surviving_young_words), 4138 _surviving_young_words(surviving_young_words), 4139 _rs_length(0), 4140 _serial_work_claim(0), 4141 _parallel_work_claim(0), 4142 _num_work_items(collection_set->region_length()), 4143 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4144 prepare_work(); 4145 } 4146 4147 ~G1FreeCollectionSetTask() { 4148 complete_work(); 4149 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4150 } 4151 4152 // Chunk size for work distribution. The chosen value has been determined experimentally 4153 // to be a good tradeoff between overhead and achievable parallelism. 4154 static uint chunk_size() { return 32; } 4155 4156 virtual void work(uint worker_id) { 4157 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4158 4159 // Claim serial work. 4160 if (_serial_work_claim == 0) { 4161 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4162 if (value == 0) { 4163 double serial_time = os::elapsedTime(); 4164 do_serial_work(); 4165 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4166 } 4167 } 4168 4169 // Start parallel work. 4170 double young_time = 0.0; 4171 bool has_young_time = false; 4172 double non_young_time = 0.0; 4173 bool has_non_young_time = false; 4174 4175 while (true) { 4176 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4177 size_t cur = end - chunk_size(); 4178 4179 if (cur >= _num_work_items) { 4180 break; 4181 } 4182 4183 EventGCPhaseParallel event; 4184 double start_time = os::elapsedTime(); 4185 4186 end = MIN2(end, _num_work_items); 4187 4188 for (; cur < end; cur++) { 4189 bool is_young = _work_items[cur].is_young; 4190 4191 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4192 4193 double end_time = os::elapsedTime(); 4194 double time_taken = end_time - start_time; 4195 if (is_young) { 4196 young_time += time_taken; 4197 has_young_time = true; 4198 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4199 } else { 4200 non_young_time += time_taken; 4201 has_non_young_time = true; 4202 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4203 } 4204 start_time = end_time; 4205 } 4206 } 4207 4208 if (has_young_time) { 4209 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4210 } 4211 if (has_non_young_time) { 4212 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4213 } 4214 } 4215 }; 4216 4217 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4218 _eden.clear(); 4219 4220 double free_cset_start_time = os::elapsedTime(); 4221 4222 { 4223 uint const num_regions = _collection_set.region_length(); 4224 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4225 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4226 4227 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4228 4229 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4230 cl.name(), num_workers, num_regions); 4231 workers()->run_task(&cl, num_workers); 4232 } 4233 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4234 4235 collection_set->clear(); 4236 } 4237 4238 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4239 private: 4240 FreeRegionList* _free_region_list; 4241 HeapRegionSet* _proxy_set; 4242 uint _humongous_objects_reclaimed; 4243 uint _humongous_regions_reclaimed; 4244 size_t _freed_bytes; 4245 public: 4246 4247 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4248 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4249 } 4250 4251 virtual bool do_heap_region(HeapRegion* r) { 4252 if (!r->is_starts_humongous()) { 4253 return false; 4254 } 4255 4256 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4257 4258 oop obj = (oop)r->bottom(); 4259 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4260 4261 // The following checks whether the humongous object is live are sufficient. 4262 // The main additional check (in addition to having a reference from the roots 4263 // or the young gen) is whether the humongous object has a remembered set entry. 4264 // 4265 // A humongous object cannot be live if there is no remembered set for it 4266 // because: 4267 // - there can be no references from within humongous starts regions referencing 4268 // the object because we never allocate other objects into them. 4269 // (I.e. there are no intra-region references that may be missed by the 4270 // remembered set) 4271 // - as soon there is a remembered set entry to the humongous starts region 4272 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4273 // until the end of a concurrent mark. 4274 // 4275 // It is not required to check whether the object has been found dead by marking 4276 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4277 // all objects allocated during that time are considered live. 4278 // SATB marking is even more conservative than the remembered set. 4279 // So if at this point in the collection there is no remembered set entry, 4280 // nobody has a reference to it. 4281 // At the start of collection we flush all refinement logs, and remembered sets 4282 // are completely up-to-date wrt to references to the humongous object. 4283 // 4284 // Other implementation considerations: 4285 // - never consider object arrays at this time because they would pose 4286 // considerable effort for cleaning up the the remembered sets. This is 4287 // required because stale remembered sets might reference locations that 4288 // are currently allocated into. 4289 uint region_idx = r->hrm_index(); 4290 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4291 !r->rem_set()->is_empty()) { 4292 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", 4293 region_idx, 4294 (size_t)obj->size() * HeapWordSize, 4295 p2i(r->bottom()), 4296 r->rem_set()->occupied(), 4297 r->rem_set()->strong_code_roots_list_length(), 4298 next_bitmap->is_marked(r->bottom()), 4299 g1h->is_humongous_reclaim_candidate(region_idx), 4300 obj->is_typeArray() 4301 ); 4302 return false; 4303 } 4304 4305 guarantee(obj->is_typeArray(), 4306 "Only eagerly reclaiming type arrays is supported, but the object " 4307 PTR_FORMAT " is not.", p2i(r->bottom())); 4308 4309 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", 4310 region_idx, 4311 (size_t)obj->size() * HeapWordSize, 4312 p2i(r->bottom()), 4313 r->rem_set()->occupied(), 4314 r->rem_set()->strong_code_roots_list_length(), 4315 next_bitmap->is_marked(r->bottom()), 4316 g1h->is_humongous_reclaim_candidate(region_idx), 4317 obj->is_typeArray() 4318 ); 4319 4320 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4321 cm->humongous_object_eagerly_reclaimed(r); 4322 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4323 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4324 region_idx, 4325 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4326 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4327 _humongous_objects_reclaimed++; 4328 do { 4329 HeapRegion* next = g1h->next_region_in_humongous(r); 4330 _freed_bytes += r->used(); 4331 r->set_containing_set(NULL); 4332 _humongous_regions_reclaimed++; 4333 g1h->free_humongous_region(r, _free_region_list); 4334 r = next; 4335 } while (r != NULL); 4336 4337 return false; 4338 } 4339 4340 uint humongous_objects_reclaimed() { 4341 return _humongous_objects_reclaimed; 4342 } 4343 4344 uint humongous_regions_reclaimed() { 4345 return _humongous_regions_reclaimed; 4346 } 4347 4348 size_t bytes_freed() const { 4349 return _freed_bytes; 4350 } 4351 }; 4352 4353 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4354 assert_at_safepoint_on_vm_thread(); 4355 4356 if (!G1EagerReclaimHumongousObjects || 4357 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4358 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4359 return; 4360 } 4361 4362 double start_time = os::elapsedTime(); 4363 4364 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4365 4366 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4367 heap_region_iterate(&cl); 4368 4369 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4370 4371 G1HRPrinter* hrp = hr_printer(); 4372 if (hrp->is_active()) { 4373 FreeRegionListIterator iter(&local_cleanup_list); 4374 while (iter.more_available()) { 4375 HeapRegion* hr = iter.get_next(); 4376 hrp->cleanup(hr); 4377 } 4378 } 4379 4380 prepend_to_freelist(&local_cleanup_list); 4381 decrement_summary_bytes(cl.bytes_freed()); 4382 4383 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4384 cl.humongous_objects_reclaimed()); 4385 } 4386 4387 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4388 public: 4389 virtual bool do_heap_region(HeapRegion* r) { 4390 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4391 G1CollectedHeap::heap()->clear_region_attr(r); 4392 r->clear_young_index_in_cset(); 4393 return false; 4394 } 4395 }; 4396 4397 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4398 G1AbandonCollectionSetClosure cl; 4399 collection_set_iterate_all(&cl); 4400 4401 collection_set->clear(); 4402 collection_set->stop_incremental_building(); 4403 } 4404 4405 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4406 return _allocator->is_retained_old_region(hr); 4407 } 4408 4409 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4410 _eden.add(hr); 4411 _policy->set_region_eden(hr); 4412 } 4413 4414 #ifdef ASSERT 4415 4416 class NoYoungRegionsClosure: public HeapRegionClosure { 4417 private: 4418 bool _success; 4419 public: 4420 NoYoungRegionsClosure() : _success(true) { } 4421 bool do_heap_region(HeapRegion* r) { 4422 if (r->is_young()) { 4423 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4424 p2i(r->bottom()), p2i(r->end())); 4425 _success = false; 4426 } 4427 return false; 4428 } 4429 bool success() { return _success; } 4430 }; 4431 4432 bool G1CollectedHeap::check_young_list_empty() { 4433 bool ret = (young_regions_count() == 0); 4434 4435 NoYoungRegionsClosure closure; 4436 heap_region_iterate(&closure); 4437 ret = ret && closure.success(); 4438 4439 return ret; 4440 } 4441 4442 #endif // ASSERT 4443 4444 class TearDownRegionSetsClosure : public HeapRegionClosure { 4445 HeapRegionSet *_old_set; 4446 4447 public: 4448 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4449 4450 bool do_heap_region(HeapRegion* r) { 4451 if (r->is_old()) { 4452 _old_set->remove(r); 4453 } else if(r->is_young()) { 4454 r->uninstall_surv_rate_group(); 4455 } else { 4456 // We ignore free regions, we'll empty the free list afterwards. 4457 // We ignore humongous and archive regions, we're not tearing down these 4458 // sets. 4459 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4460 "it cannot be another type"); 4461 } 4462 return false; 4463 } 4464 4465 ~TearDownRegionSetsClosure() { 4466 assert(_old_set->is_empty(), "post-condition"); 4467 } 4468 }; 4469 4470 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4471 assert_at_safepoint_on_vm_thread(); 4472 4473 if (!free_list_only) { 4474 TearDownRegionSetsClosure cl(&_old_set); 4475 heap_region_iterate(&cl); 4476 4477 // Note that emptying the _young_list is postponed and instead done as 4478 // the first step when rebuilding the regions sets again. The reason for 4479 // this is that during a full GC string deduplication needs to know if 4480 // a collected region was young or old when the full GC was initiated. 4481 } 4482 _hrm->remove_all_free_regions(); 4483 } 4484 4485 void G1CollectedHeap::increase_used(size_t bytes) { 4486 _summary_bytes_used += bytes; 4487 } 4488 4489 void G1CollectedHeap::decrease_used(size_t bytes) { 4490 assert(_summary_bytes_used >= bytes, 4491 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4492 _summary_bytes_used, bytes); 4493 _summary_bytes_used -= bytes; 4494 } 4495 4496 void G1CollectedHeap::set_used(size_t bytes) { 4497 _summary_bytes_used = bytes; 4498 } 4499 4500 class RebuildRegionSetsClosure : public HeapRegionClosure { 4501 private: 4502 bool _free_list_only; 4503 4504 HeapRegionSet* _old_set; 4505 HeapRegionManager* _hrm; 4506 4507 size_t _total_used; 4508 4509 public: 4510 RebuildRegionSetsClosure(bool free_list_only, 4511 HeapRegionSet* old_set, 4512 HeapRegionManager* hrm) : 4513 _free_list_only(free_list_only), 4514 _old_set(old_set), _hrm(hrm), _total_used(0) { 4515 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4516 if (!free_list_only) { 4517 assert(_old_set->is_empty(), "pre-condition"); 4518 } 4519 } 4520 4521 bool do_heap_region(HeapRegion* r) { 4522 if (r->is_empty()) { 4523 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4524 // Add free regions to the free list 4525 r->set_free(); 4526 _hrm->insert_into_free_list(r); 4527 } else if (!_free_list_only) { 4528 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4529 4530 if (r->is_archive() || r->is_humongous()) { 4531 // We ignore archive and humongous regions. We left these sets unchanged. 4532 } else { 4533 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4534 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4535 r->move_to_old(); 4536 _old_set->add(r); 4537 } 4538 _total_used += r->used(); 4539 } 4540 4541 return false; 4542 } 4543 4544 size_t total_used() { 4545 return _total_used; 4546 } 4547 }; 4548 4549 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4550 assert_at_safepoint_on_vm_thread(); 4551 4552 if (!free_list_only) { 4553 _eden.clear(); 4554 _survivor.clear(); 4555 } 4556 4557 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4558 heap_region_iterate(&cl); 4559 4560 if (!free_list_only) { 4561 set_used(cl.total_used()); 4562 if (_archive_allocator != NULL) { 4563 _archive_allocator->clear_used(); 4564 } 4565 } 4566 assert_used_and_recalculate_used_equal(this); 4567 } 4568 4569 // Methods for the mutator alloc region 4570 4571 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4572 bool force, 4573 uint node_index) { 4574 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4575 bool should_allocate = policy()->should_allocate_mutator_region(); 4576 if (force || should_allocate) { 4577 HeapRegion* new_alloc_region = new_region(word_size, 4578 HeapRegionType::Eden, 4579 false /* do_expand */, 4580 node_index); 4581 if (new_alloc_region != NULL) { 4582 set_region_short_lived_locked(new_alloc_region); 4583 _hr_printer.alloc(new_alloc_region, !should_allocate); 4584 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4585 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4586 return new_alloc_region; 4587 } 4588 } 4589 return NULL; 4590 } 4591 4592 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4593 size_t allocated_bytes) { 4594 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4595 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4596 4597 collection_set()->add_eden_region(alloc_region); 4598 increase_used(allocated_bytes); 4599 _eden.add_used_bytes(allocated_bytes); 4600 _hr_printer.retire(alloc_region); 4601 4602 // We update the eden sizes here, when the region is retired, 4603 // instead of when it's allocated, since this is the point that its 4604 // used space has been recorded in _summary_bytes_used. 4605 g1mm()->update_eden_size(); 4606 } 4607 4608 // Methods for the GC alloc regions 4609 4610 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4611 if (dest.is_old()) { 4612 return true; 4613 } else { 4614 return survivor_regions_count() < policy()->max_survivor_regions(); 4615 } 4616 } 4617 4618 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) { 4619 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4620 4621 if (!has_more_regions(dest)) { 4622 return NULL; 4623 } 4624 4625 HeapRegionType type; 4626 if (dest.is_young()) { 4627 type = HeapRegionType::Survivor; 4628 } else { 4629 type = HeapRegionType::Old; 4630 } 4631 4632 HeapRegion* new_alloc_region = new_region(word_size, 4633 type, 4634 true /* do_expand */); 4635 4636 if (new_alloc_region != NULL) { 4637 if (type.is_survivor()) { 4638 new_alloc_region->set_survivor(); 4639 _survivor.add(new_alloc_region); 4640 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4641 } else { 4642 new_alloc_region->set_old(); 4643 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4644 } 4645 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4646 register_region_with_region_attr(new_alloc_region); 4647 _hr_printer.alloc(new_alloc_region); 4648 return new_alloc_region; 4649 } 4650 return NULL; 4651 } 4652 4653 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4654 size_t allocated_bytes, 4655 G1HeapRegionAttr dest) { 4656 policy()->record_bytes_copied_during_gc(allocated_bytes); 4657 if (dest.is_old()) { 4658 old_set_add(alloc_region); 4659 } else { 4660 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4661 _survivor.add_used_bytes(allocated_bytes); 4662 } 4663 4664 bool const during_im = collector_state()->in_initial_mark_gc(); 4665 if (during_im && allocated_bytes > 0) { 4666 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4667 } 4668 _hr_printer.retire(alloc_region); 4669 } 4670 4671 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4672 bool expanded = false; 4673 uint index = _hrm->find_highest_free(&expanded); 4674 4675 if (index != G1_NO_HRM_INDEX) { 4676 if (expanded) { 4677 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4678 HeapRegion::GrainWords * HeapWordSize); 4679 } 4680 _hrm->allocate_free_regions_starting_at(index, 1); 4681 return region_at(index); 4682 } 4683 return NULL; 4684 } 4685 4686 // Optimized nmethod scanning 4687 4688 class RegisterNMethodOopClosure: public OopClosure { 4689 G1CollectedHeap* _g1h; 4690 nmethod* _nm; 4691 4692 template <class T> void do_oop_work(T* p) { 4693 T heap_oop = RawAccess<>::oop_load(p); 4694 if (!CompressedOops::is_null(heap_oop)) { 4695 oop obj = CompressedOops::decode_not_null(heap_oop); 4696 HeapRegion* hr = _g1h->heap_region_containing(obj); 4697 assert(!hr->is_continues_humongous(), 4698 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4699 " starting at " HR_FORMAT, 4700 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4701 4702 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4703 hr->add_strong_code_root_locked(_nm); 4704 } 4705 } 4706 4707 public: 4708 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4709 _g1h(g1h), _nm(nm) {} 4710 4711 void do_oop(oop* p) { do_oop_work(p); } 4712 void do_oop(narrowOop* p) { do_oop_work(p); } 4713 }; 4714 4715 class UnregisterNMethodOopClosure: public OopClosure { 4716 G1CollectedHeap* _g1h; 4717 nmethod* _nm; 4718 4719 template <class T> void do_oop_work(T* p) { 4720 T heap_oop = RawAccess<>::oop_load(p); 4721 if (!CompressedOops::is_null(heap_oop)) { 4722 oop obj = CompressedOops::decode_not_null(heap_oop); 4723 HeapRegion* hr = _g1h->heap_region_containing(obj); 4724 assert(!hr->is_continues_humongous(), 4725 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4726 " starting at " HR_FORMAT, 4727 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4728 4729 hr->remove_strong_code_root(_nm); 4730 } 4731 } 4732 4733 public: 4734 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4735 _g1h(g1h), _nm(nm) {} 4736 4737 void do_oop(oop* p) { do_oop_work(p); } 4738 void do_oop(narrowOop* p) { do_oop_work(p); } 4739 }; 4740 4741 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4742 guarantee(nm != NULL, "sanity"); 4743 RegisterNMethodOopClosure reg_cl(this, nm); 4744 nm->oops_do(®_cl); 4745 } 4746 4747 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4748 guarantee(nm != NULL, "sanity"); 4749 UnregisterNMethodOopClosure reg_cl(this, nm); 4750 nm->oops_do(®_cl, true); 4751 } 4752 4753 void G1CollectedHeap::purge_code_root_memory() { 4754 double purge_start = os::elapsedTime(); 4755 G1CodeRootSet::purge(); 4756 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4757 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4758 } 4759 4760 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4761 G1CollectedHeap* _g1h; 4762 4763 public: 4764 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4765 _g1h(g1h) {} 4766 4767 void do_code_blob(CodeBlob* cb) { 4768 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4769 if (nm == NULL) { 4770 return; 4771 } 4772 4773 _g1h->register_nmethod(nm); 4774 } 4775 }; 4776 4777 void G1CollectedHeap::rebuild_strong_code_roots() { 4778 RebuildStrongCodeRootClosure blob_cl(this); 4779 CodeCache::blobs_do(&blob_cl); 4780 } 4781 4782 void G1CollectedHeap::initialize_serviceability() { 4783 _g1mm->initialize_serviceability(); 4784 } 4785 4786 MemoryUsage G1CollectedHeap::memory_usage() { 4787 return _g1mm->memory_usage(); 4788 } 4789 4790 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4791 return _g1mm->memory_managers(); 4792 } 4793 4794 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4795 return _g1mm->memory_pools(); 4796 }