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