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