1 /* 2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/g1Allocator.inline.hpp" 32 #include "gc/g1/g1Arguments.hpp" 33 #include "gc/g1/g1BarrierSet.hpp" 34 #include "gc/g1/g1CardTableEntryClosure.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectionSet.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 41 #include "gc/g1/g1DirtyCardQueue.hpp" 42 #include "gc/g1/g1EvacStats.inline.hpp" 43 #include "gc/g1/g1FullCollector.hpp" 44 #include "gc/g1/g1GCPhaseTimes.hpp" 45 #include "gc/g1/g1HeapSizingPolicy.hpp" 46 #include "gc/g1/g1HeapTransition.hpp" 47 #include "gc/g1/g1HeapVerifier.hpp" 48 #include "gc/g1/g1HotCardCache.hpp" 49 #include "gc/g1/g1MemoryPool.hpp" 50 #include "gc/g1/g1OopClosures.inline.hpp" 51 #include "gc/g1/g1ParallelCleaning.hpp" 52 #include "gc/g1/g1ParScanThreadState.inline.hpp" 53 #include "gc/g1/g1Policy.hpp" 54 #include "gc/g1/g1RedirtyCardsQueue.hpp" 55 #include "gc/g1/g1RegionToSpaceMapper.hpp" 56 #include "gc/g1/g1RemSet.hpp" 57 #include "gc/g1/g1RootClosures.hpp" 58 #include "gc/g1/g1RootProcessor.hpp" 59 #include "gc/g1/g1SATBMarkQueueSet.hpp" 60 #include "gc/g1/g1StringDedup.hpp" 61 #include "gc/g1/g1ThreadLocalData.hpp" 62 #include "gc/g1/g1Trace.hpp" 63 #include "gc/g1/g1YCTypes.hpp" 64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 65 #include "gc/g1/g1VMOperations.hpp" 66 #include "gc/g1/heapRegion.inline.hpp" 67 #include "gc/g1/heapRegionRemSet.hpp" 68 #include "gc/g1/heapRegionSet.inline.hpp" 69 #include "gc/shared/gcBehaviours.hpp" 70 #include "gc/shared/gcHeapSummary.hpp" 71 #include "gc/shared/gcId.hpp" 72 #include "gc/shared/gcLocker.hpp" 73 #include "gc/shared/gcTimer.hpp" 74 #include "gc/shared/gcTraceTime.inline.hpp" 75 #include "gc/shared/generationSpec.hpp" 76 #include "gc/shared/isGCActiveMark.hpp" 77 #include "gc/shared/locationPrinter.inline.hpp" 78 #include "gc/shared/oopStorageParState.hpp" 79 #include "gc/shared/preservedMarks.inline.hpp" 80 #include "gc/shared/suspendibleThreadSet.hpp" 81 #include "gc/shared/referenceProcessor.inline.hpp" 82 #include "gc/shared/taskqueue.inline.hpp" 83 #include "gc/shared/weakProcessor.inline.hpp" 84 #include "gc/shared/workerPolicy.hpp" 85 #include "logging/log.hpp" 86 #include "memory/allocation.hpp" 87 #include "memory/iterator.hpp" 88 #include "memory/resourceArea.hpp" 89 #include "memory/universe.hpp" 90 #include "oops/access.inline.hpp" 91 #include "oops/compressedOops.inline.hpp" 92 #include "oops/oop.inline.hpp" 93 #include "runtime/atomic.hpp" 94 #include "runtime/flags/flagSetting.hpp" 95 #include "runtime/handles.inline.hpp" 96 #include "runtime/init.hpp" 97 #include "runtime/orderAccess.hpp" 98 #include "runtime/threadSMR.hpp" 99 #include "runtime/vmThread.hpp" 100 #include "utilities/align.hpp" 101 #include "utilities/globalDefinitions.hpp" 102 #include "utilities/stack.inline.hpp" 103 104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 105 106 // INVARIANTS/NOTES 107 // 108 // All allocation activity covered by the G1CollectedHeap interface is 109 // serialized by acquiring the HeapLock. This happens in mem_allocate 110 // and allocate_new_tlab, which are the "entry" points to the 111 // allocation code from the rest of the JVM. (Note that this does not 112 // apply to TLAB allocation, which is not part of this interface: it 113 // is done by clients of this interface.) 114 115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 116 private: 117 size_t _num_dirtied; 118 G1CollectedHeap* _g1h; 119 G1CardTable* _g1_ct; 120 121 HeapRegion* region_for_card(CardValue* card_ptr) const { 122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 123 } 124 125 bool will_become_free(HeapRegion* hr) const { 126 // A region will be freed by free_collection_set if the region is in the 127 // collection set and has not had an evacuation failure. 128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 129 } 130 131 public: 132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 134 135 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_cards() == 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 _gc_tracer_stw->initialize(); 1571 1572 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1573 } 1574 1575 static size_t actual_reserved_page_size(ReservedSpace rs) { 1576 size_t page_size = os::vm_page_size(); 1577 if (UseLargePages) { 1578 // There are two ways to manage large page memory. 1579 // 1. OS supports committing large page memory. 1580 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1581 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1582 // we reserved memory without large page. 1583 if (os::can_commit_large_page_memory() || rs.special()) { 1584 // An alignment at ReservedSpace comes from preferred page size or 1585 // heap alignment, and if the alignment came from heap alignment, it could be 1586 // larger than large pages size. So need to cap with the large page size. 1587 page_size = MIN2(rs.alignment(), os::large_page_size()); 1588 } 1589 } 1590 1591 return page_size; 1592 } 1593 1594 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1595 size_t size, 1596 size_t translation_factor) { 1597 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1598 // Allocate a new reserved space, preferring to use large pages. 1599 ReservedSpace rs(size, preferred_page_size); 1600 size_t page_size = actual_reserved_page_size(rs); 1601 G1RegionToSpaceMapper* result = 1602 G1RegionToSpaceMapper::create_mapper(rs, 1603 size, 1604 page_size, 1605 HeapRegion::GrainBytes, 1606 translation_factor, 1607 mtGC); 1608 1609 os::trace_page_sizes_for_requested_size(description, 1610 size, 1611 preferred_page_size, 1612 page_size, 1613 rs.base(), 1614 rs.size()); 1615 1616 return result; 1617 } 1618 1619 jint G1CollectedHeap::initialize_concurrent_refinement() { 1620 jint ecode = JNI_OK; 1621 _cr = G1ConcurrentRefine::create(&ecode); 1622 return ecode; 1623 } 1624 1625 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1626 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1627 if (_young_gen_sampling_thread->osthread() == NULL) { 1628 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1629 return JNI_ENOMEM; 1630 } 1631 return JNI_OK; 1632 } 1633 1634 jint G1CollectedHeap::initialize() { 1635 os::enable_vtime(); 1636 1637 // Necessary to satisfy locking discipline assertions. 1638 1639 MutexLocker x(Heap_lock); 1640 1641 // While there are no constraints in the GC code that HeapWordSize 1642 // be any particular value, there are multiple other areas in the 1643 // system which believe this to be true (e.g. oop->object_size in some 1644 // cases incorrectly returns the size in wordSize units rather than 1645 // HeapWordSize). 1646 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1647 1648 size_t init_byte_size = InitialHeapSize; 1649 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1650 1651 // Ensure that the sizes are properly aligned. 1652 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1653 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1654 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1655 1656 // Reserve the maximum. 1657 1658 // When compressed oops are enabled, the preferred heap base 1659 // is calculated by subtracting the requested size from the 1660 // 32Gb boundary and using the result as the base address for 1661 // heap reservation. If the requested size is not aligned to 1662 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1663 // into the ReservedHeapSpace constructor) then the actual 1664 // base of the reserved heap may end up differing from the 1665 // address that was requested (i.e. the preferred heap base). 1666 // If this happens then we could end up using a non-optimal 1667 // compressed oops mode. 1668 1669 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1670 HeapAlignment); 1671 1672 initialize_reserved_region(heap_rs); 1673 1674 // Create the barrier set for the entire reserved region. 1675 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1676 ct->initialize(); 1677 G1BarrierSet* bs = new G1BarrierSet(ct); 1678 bs->initialize(); 1679 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1680 BarrierSet::set_barrier_set(bs); 1681 _card_table = ct; 1682 1683 { 1684 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1685 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1686 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1687 } 1688 1689 // Create the hot card cache. 1690 _hot_card_cache = new G1HotCardCache(this); 1691 1692 // Carve out the G1 part of the heap. 1693 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1694 size_t page_size = actual_reserved_page_size(heap_rs); 1695 G1RegionToSpaceMapper* heap_storage = 1696 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1697 g1_rs.size(), 1698 page_size, 1699 HeapRegion::GrainBytes, 1700 1, 1701 mtJavaHeap); 1702 if(heap_storage == NULL) { 1703 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1704 return JNI_ERR; 1705 } 1706 1707 os::trace_page_sizes("Heap", 1708 MinHeapSize, 1709 reserved_byte_size, 1710 page_size, 1711 heap_rs.base(), 1712 heap_rs.size()); 1713 heap_storage->set_mapping_changed_listener(&_listener); 1714 1715 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1716 G1RegionToSpaceMapper* bot_storage = 1717 create_aux_memory_mapper("Block Offset Table", 1718 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1719 G1BlockOffsetTable::heap_map_factor()); 1720 1721 G1RegionToSpaceMapper* cardtable_storage = 1722 create_aux_memory_mapper("Card Table", 1723 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1724 G1CardTable::heap_map_factor()); 1725 1726 G1RegionToSpaceMapper* card_counts_storage = 1727 create_aux_memory_mapper("Card Counts Table", 1728 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1729 G1CardCounts::heap_map_factor()); 1730 1731 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1732 G1RegionToSpaceMapper* prev_bitmap_storage = 1733 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1734 G1RegionToSpaceMapper* next_bitmap_storage = 1735 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1736 1737 _hrm = HeapRegionManager::create_manager(this); 1738 1739 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1740 _card_table->initialize(cardtable_storage); 1741 1742 // Do later initialization work for concurrent refinement. 1743 _hot_card_cache->initialize(card_counts_storage); 1744 1745 // 6843694 - ensure that the maximum region index can fit 1746 // in the remembered set structures. 1747 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1748 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1749 1750 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1751 // start within the first card. 1752 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1753 // Also create a G1 rem set. 1754 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1755 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1756 1757 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1758 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1759 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1760 "too many cards per region"); 1761 1762 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1763 1764 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1765 1766 { 1767 HeapWord* start = _hrm->reserved().start(); 1768 HeapWord* end = _hrm->reserved().end(); 1769 size_t granularity = HeapRegion::GrainBytes; 1770 1771 _region_attr.initialize(start, end, granularity); 1772 _humongous_reclaim_candidates.initialize(start, end, granularity); 1773 } 1774 1775 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1776 true /* are_GC_task_threads */, 1777 false /* are_ConcurrentGC_threads */); 1778 if (_workers == NULL) { 1779 return JNI_ENOMEM; 1780 } 1781 _workers->initialize_workers(); 1782 1783 // Create the G1ConcurrentMark data structure and thread. 1784 // (Must do this late, so that "max_regions" is defined.) 1785 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1786 if (_cm == NULL || !_cm->completed_initialization()) { 1787 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1788 return JNI_ENOMEM; 1789 } 1790 _cm_thread = _cm->cm_thread(); 1791 1792 // Now expand into the initial heap size. 1793 if (!expand(init_byte_size, _workers)) { 1794 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1795 return JNI_ENOMEM; 1796 } 1797 1798 // Perform any initialization actions delegated to the policy. 1799 policy()->init(this, &_collection_set); 1800 1801 jint ecode = initialize_concurrent_refinement(); 1802 if (ecode != JNI_OK) { 1803 return ecode; 1804 } 1805 1806 ecode = initialize_young_gen_sampling_thread(); 1807 if (ecode != JNI_OK) { 1808 return ecode; 1809 } 1810 1811 { 1812 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1813 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1814 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1815 } 1816 1817 // Here we allocate the dummy HeapRegion that is required by the 1818 // G1AllocRegion class. 1819 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1820 1821 // We'll re-use the same region whether the alloc region will 1822 // require BOT updates or not and, if it doesn't, then a non-young 1823 // region will complain that it cannot support allocations without 1824 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1825 dummy_region->set_eden(); 1826 // Make sure it's full. 1827 dummy_region->set_top(dummy_region->end()); 1828 G1AllocRegion::setup(this, dummy_region); 1829 1830 _allocator->init_mutator_alloc_region(); 1831 1832 // Do create of the monitoring and management support so that 1833 // values in the heap have been properly initialized. 1834 _g1mm = new G1MonitoringSupport(this); 1835 1836 G1StringDedup::initialize(); 1837 1838 _preserved_marks_set.init(ParallelGCThreads); 1839 1840 _collection_set.initialize(max_regions()); 1841 1842 return JNI_OK; 1843 } 1844 1845 void G1CollectedHeap::stop() { 1846 // Stop all concurrent threads. We do this to make sure these threads 1847 // do not continue to execute and access resources (e.g. logging) 1848 // that are destroyed during shutdown. 1849 _cr->stop(); 1850 _young_gen_sampling_thread->stop(); 1851 _cm_thread->stop(); 1852 if (G1StringDedup::is_enabled()) { 1853 G1StringDedup::stop(); 1854 } 1855 } 1856 1857 void G1CollectedHeap::safepoint_synchronize_begin() { 1858 SuspendibleThreadSet::synchronize(); 1859 } 1860 1861 void G1CollectedHeap::safepoint_synchronize_end() { 1862 SuspendibleThreadSet::desynchronize(); 1863 } 1864 1865 void G1CollectedHeap::post_initialize() { 1866 CollectedHeap::post_initialize(); 1867 ref_processing_init(); 1868 } 1869 1870 void G1CollectedHeap::ref_processing_init() { 1871 // Reference processing in G1 currently works as follows: 1872 // 1873 // * There are two reference processor instances. One is 1874 // used to record and process discovered references 1875 // during concurrent marking; the other is used to 1876 // record and process references during STW pauses 1877 // (both full and incremental). 1878 // * Both ref processors need to 'span' the entire heap as 1879 // the regions in the collection set may be dotted around. 1880 // 1881 // * For the concurrent marking ref processor: 1882 // * Reference discovery is enabled at initial marking. 1883 // * Reference discovery is disabled and the discovered 1884 // references processed etc during remarking. 1885 // * Reference discovery is MT (see below). 1886 // * Reference discovery requires a barrier (see below). 1887 // * Reference processing may or may not be MT 1888 // (depending on the value of ParallelRefProcEnabled 1889 // and ParallelGCThreads). 1890 // * A full GC disables reference discovery by the CM 1891 // ref processor and abandons any entries on it's 1892 // discovered lists. 1893 // 1894 // * For the STW processor: 1895 // * Non MT discovery is enabled at the start of a full GC. 1896 // * Processing and enqueueing during a full GC is non-MT. 1897 // * During a full GC, references are processed after marking. 1898 // 1899 // * Discovery (may or may not be MT) is enabled at the start 1900 // of an incremental evacuation pause. 1901 // * References are processed near the end of a STW evacuation pause. 1902 // * For both types of GC: 1903 // * Discovery is atomic - i.e. not concurrent. 1904 // * Reference discovery will not need a barrier. 1905 1906 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1907 1908 // Concurrent Mark ref processor 1909 _ref_processor_cm = 1910 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1911 mt_processing, // mt processing 1912 ParallelGCThreads, // degree of mt processing 1913 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1914 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1915 false, // Reference discovery is not atomic 1916 &_is_alive_closure_cm, // is alive closure 1917 true); // allow changes to number of processing threads 1918 1919 // STW ref processor 1920 _ref_processor_stw = 1921 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1922 mt_processing, // mt processing 1923 ParallelGCThreads, // degree of mt processing 1924 (ParallelGCThreads > 1), // mt discovery 1925 ParallelGCThreads, // degree of mt discovery 1926 true, // Reference discovery is atomic 1927 &_is_alive_closure_stw, // is alive closure 1928 true); // allow changes to number of processing threads 1929 } 1930 1931 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1932 return &_soft_ref_policy; 1933 } 1934 1935 size_t G1CollectedHeap::capacity() const { 1936 return _hrm->length() * HeapRegion::GrainBytes; 1937 } 1938 1939 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1940 return _hrm->total_free_bytes(); 1941 } 1942 1943 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1944 _hot_card_cache->drain(cl, worker_i); 1945 } 1946 1947 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1948 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1949 while (dcqs.apply_closure_during_gc(cl, worker_i)) {} 1950 assert(dcqs.num_cards() == 0, "Completed buffers exist!"); 1951 } 1952 1953 // Computes the sum of the storage used by the various regions. 1954 size_t G1CollectedHeap::used() const { 1955 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1956 if (_archive_allocator != NULL) { 1957 result += _archive_allocator->used(); 1958 } 1959 return result; 1960 } 1961 1962 size_t G1CollectedHeap::used_unlocked() const { 1963 return _summary_bytes_used; 1964 } 1965 1966 class SumUsedClosure: public HeapRegionClosure { 1967 size_t _used; 1968 public: 1969 SumUsedClosure() : _used(0) {} 1970 bool do_heap_region(HeapRegion* r) { 1971 _used += r->used(); 1972 return false; 1973 } 1974 size_t result() { return _used; } 1975 }; 1976 1977 size_t G1CollectedHeap::recalculate_used() const { 1978 SumUsedClosure blk; 1979 heap_region_iterate(&blk); 1980 return blk.result(); 1981 } 1982 1983 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1984 switch (cause) { 1985 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1986 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1987 case GCCause::_wb_conc_mark: return true; 1988 default : return false; 1989 } 1990 } 1991 1992 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1993 switch (cause) { 1994 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1995 case GCCause::_g1_humongous_allocation: return true; 1996 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1997 default: return is_user_requested_concurrent_full_gc(cause); 1998 } 1999 } 2000 2001 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2002 if(policy()->force_upgrade_to_full()) { 2003 return true; 2004 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2005 return false; 2006 } else if (has_regions_left_for_allocation()) { 2007 return false; 2008 } else { 2009 return true; 2010 } 2011 } 2012 2013 #ifndef PRODUCT 2014 void G1CollectedHeap::allocate_dummy_regions() { 2015 // Let's fill up most of the region 2016 size_t word_size = HeapRegion::GrainWords - 1024; 2017 // And as a result the region we'll allocate will be humongous. 2018 guarantee(is_humongous(word_size), "sanity"); 2019 2020 // _filler_array_max_size is set to humongous object threshold 2021 // but temporarily change it to use CollectedHeap::fill_with_object(). 2022 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2023 2024 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2025 // Let's use the existing mechanism for the allocation 2026 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2027 if (dummy_obj != NULL) { 2028 MemRegion mr(dummy_obj, word_size); 2029 CollectedHeap::fill_with_object(mr); 2030 } else { 2031 // If we can't allocate once, we probably cannot allocate 2032 // again. Let's get out of the loop. 2033 break; 2034 } 2035 } 2036 } 2037 #endif // !PRODUCT 2038 2039 void G1CollectedHeap::increment_old_marking_cycles_started() { 2040 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2041 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2042 "Wrong marking cycle count (started: %d, completed: %d)", 2043 _old_marking_cycles_started, _old_marking_cycles_completed); 2044 2045 _old_marking_cycles_started++; 2046 } 2047 2048 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2049 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2050 2051 // We assume that if concurrent == true, then the caller is a 2052 // concurrent thread that was joined the Suspendible Thread 2053 // Set. If there's ever a cheap way to check this, we should add an 2054 // assert here. 2055 2056 // Given that this method is called at the end of a Full GC or of a 2057 // concurrent cycle, and those can be nested (i.e., a Full GC can 2058 // interrupt a concurrent cycle), the number of full collections 2059 // completed should be either one (in the case where there was no 2060 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2061 // behind the number of full collections started. 2062 2063 // This is the case for the inner caller, i.e. a Full GC. 2064 assert(concurrent || 2065 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2066 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2067 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2068 "is inconsistent with _old_marking_cycles_completed = %u", 2069 _old_marking_cycles_started, _old_marking_cycles_completed); 2070 2071 // This is the case for the outer caller, i.e. the concurrent cycle. 2072 assert(!concurrent || 2073 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2074 "for outer caller (concurrent cycle): " 2075 "_old_marking_cycles_started = %u " 2076 "is inconsistent with _old_marking_cycles_completed = %u", 2077 _old_marking_cycles_started, _old_marking_cycles_completed); 2078 2079 _old_marking_cycles_completed += 1; 2080 2081 // We need to clear the "in_progress" flag in the CM thread before 2082 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2083 // is set) so that if a waiter requests another System.gc() it doesn't 2084 // incorrectly see that a marking cycle is still in progress. 2085 if (concurrent) { 2086 _cm_thread->set_idle(); 2087 } 2088 2089 // This notify_all() will ensure that a thread that called 2090 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2091 // and it's waiting for a full GC to finish will be woken up. It is 2092 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2093 FullGCCount_lock->notify_all(); 2094 } 2095 2096 void G1CollectedHeap::collect(GCCause::Cause cause) { 2097 try_collect(cause, true); 2098 } 2099 2100 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2101 assert_heap_not_locked(); 2102 2103 bool gc_succeeded; 2104 bool should_retry_gc; 2105 2106 do { 2107 should_retry_gc = false; 2108 2109 uint gc_count_before; 2110 uint old_marking_count_before; 2111 uint full_gc_count_before; 2112 2113 { 2114 MutexLocker ml(Heap_lock); 2115 2116 // Read the GC count while holding the Heap_lock 2117 gc_count_before = total_collections(); 2118 full_gc_count_before = total_full_collections(); 2119 old_marking_count_before = _old_marking_cycles_started; 2120 } 2121 2122 if (should_do_concurrent_full_gc(cause)) { 2123 // Schedule an initial-mark evacuation pause that will start a 2124 // concurrent cycle. We're setting word_size to 0 which means that 2125 // we are not requesting a post-GC allocation. 2126 VM_G1CollectForAllocation op(0, /* word_size */ 2127 gc_count_before, 2128 cause, 2129 true, /* should_initiate_conc_mark */ 2130 policy()->max_pause_time_ms()); 2131 VMThread::execute(&op); 2132 gc_succeeded = op.gc_succeeded(); 2133 if (!gc_succeeded && retry_on_gc_failure) { 2134 if (old_marking_count_before == _old_marking_cycles_started) { 2135 should_retry_gc = op.should_retry_gc(); 2136 } else { 2137 // A Full GC happened while we were trying to schedule the 2138 // concurrent cycle. No point in starting a new cycle given 2139 // that the whole heap was collected anyway. 2140 } 2141 2142 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2143 GCLocker::stall_until_clear(); 2144 } 2145 } 2146 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2147 // Return false to be consistent with VMOp failure due to 2148 // another collection slipping in after our gc_count but before 2149 // our request is processed. _gc_locker collections upgraded by 2150 // GCLockerInvokesConcurrent are handled above and never discarded. 2151 return false; 2152 } else { 2153 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2154 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2155 2156 // Schedule a standard evacuation pause. We're setting word_size 2157 // to 0 which means that we are not requesting a post-GC allocation. 2158 VM_G1CollectForAllocation op(0, /* word_size */ 2159 gc_count_before, 2160 cause, 2161 false, /* should_initiate_conc_mark */ 2162 policy()->max_pause_time_ms()); 2163 VMThread::execute(&op); 2164 gc_succeeded = op.gc_succeeded(); 2165 } else { 2166 // Schedule a Full GC. 2167 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2168 VMThread::execute(&op); 2169 gc_succeeded = op.gc_succeeded(); 2170 } 2171 } 2172 } while (should_retry_gc); 2173 return gc_succeeded; 2174 } 2175 2176 bool G1CollectedHeap::is_in(const void* p) const { 2177 if (_hrm->reserved().contains(p)) { 2178 // Given that we know that p is in the reserved space, 2179 // heap_region_containing() should successfully 2180 // return the containing region. 2181 HeapRegion* hr = heap_region_containing(p); 2182 return hr->is_in(p); 2183 } else { 2184 return false; 2185 } 2186 } 2187 2188 #ifdef ASSERT 2189 bool G1CollectedHeap::is_in_exact(const void* p) const { 2190 bool contains = reserved_region().contains(p); 2191 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2192 if (contains && available) { 2193 return true; 2194 } else { 2195 return false; 2196 } 2197 } 2198 #endif 2199 2200 // Iteration functions. 2201 2202 // Iterates an ObjectClosure over all objects within a HeapRegion. 2203 2204 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2205 ObjectClosure* _cl; 2206 public: 2207 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2208 bool do_heap_region(HeapRegion* r) { 2209 if (!r->is_continues_humongous()) { 2210 r->object_iterate(_cl); 2211 } 2212 return false; 2213 } 2214 }; 2215 2216 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2217 IterateObjectClosureRegionClosure blk(cl); 2218 heap_region_iterate(&blk); 2219 } 2220 2221 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2222 _hrm->iterate(cl); 2223 } 2224 2225 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2226 HeapRegionClaimer *hrclaimer, 2227 uint worker_id) const { 2228 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2229 } 2230 2231 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2232 HeapRegionClaimer *hrclaimer) const { 2233 _hrm->par_iterate(cl, hrclaimer, 0); 2234 } 2235 2236 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2237 _collection_set.iterate(cl); 2238 } 2239 2240 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2241 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2242 } 2243 2244 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2245 HeapRegion* hr = heap_region_containing(addr); 2246 return hr->block_start(addr); 2247 } 2248 2249 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2250 HeapRegion* hr = heap_region_containing(addr); 2251 return hr->block_is_obj(addr); 2252 } 2253 2254 bool G1CollectedHeap::supports_tlab_allocation() const { 2255 return true; 2256 } 2257 2258 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2259 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2260 } 2261 2262 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2263 return _eden.length() * HeapRegion::GrainBytes; 2264 } 2265 2266 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2267 // must be equal to the humongous object limit. 2268 size_t G1CollectedHeap::max_tlab_size() const { 2269 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2270 } 2271 2272 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2273 return _allocator->unsafe_max_tlab_alloc(); 2274 } 2275 2276 size_t G1CollectedHeap::max_capacity() const { 2277 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2278 } 2279 2280 size_t G1CollectedHeap::max_reserved_capacity() const { 2281 return _hrm->max_length() * HeapRegion::GrainBytes; 2282 } 2283 2284 jlong G1CollectedHeap::millis_since_last_gc() { 2285 // See the notes in GenCollectedHeap::millis_since_last_gc() 2286 // for more information about the implementation. 2287 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2288 _policy->collection_pause_end_millis(); 2289 if (ret_val < 0) { 2290 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2291 ". returning zero instead.", ret_val); 2292 return 0; 2293 } 2294 return ret_val; 2295 } 2296 2297 void G1CollectedHeap::deduplicate_string(oop str) { 2298 assert(java_lang_String::is_instance(str), "invariant"); 2299 2300 if (G1StringDedup::is_enabled()) { 2301 G1StringDedup::deduplicate(str); 2302 } 2303 } 2304 2305 void G1CollectedHeap::prepare_for_verify() { 2306 _verifier->prepare_for_verify(); 2307 } 2308 2309 void G1CollectedHeap::verify(VerifyOption vo) { 2310 _verifier->verify(vo); 2311 } 2312 2313 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2314 return true; 2315 } 2316 2317 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2318 return _cm_thread->request_concurrent_phase(phase); 2319 } 2320 2321 bool G1CollectedHeap::is_heterogeneous_heap() const { 2322 return G1Arguments::is_heterogeneous_heap(); 2323 } 2324 2325 class PrintRegionClosure: public HeapRegionClosure { 2326 outputStream* _st; 2327 public: 2328 PrintRegionClosure(outputStream* st) : _st(st) {} 2329 bool do_heap_region(HeapRegion* r) { 2330 r->print_on(_st); 2331 return false; 2332 } 2333 }; 2334 2335 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2336 const HeapRegion* hr, 2337 const VerifyOption vo) const { 2338 switch (vo) { 2339 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2340 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2341 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2342 default: ShouldNotReachHere(); 2343 } 2344 return false; // keep some compilers happy 2345 } 2346 2347 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2348 const VerifyOption vo) const { 2349 switch (vo) { 2350 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2351 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2352 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2353 default: ShouldNotReachHere(); 2354 } 2355 return false; // keep some compilers happy 2356 } 2357 2358 void G1CollectedHeap::print_heap_regions() const { 2359 LogTarget(Trace, gc, heap, region) lt; 2360 if (lt.is_enabled()) { 2361 LogStream ls(lt); 2362 print_regions_on(&ls); 2363 } 2364 } 2365 2366 void G1CollectedHeap::print_on(outputStream* st) const { 2367 st->print(" %-20s", "garbage-first heap"); 2368 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2369 capacity()/K, used_unlocked()/K); 2370 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2371 p2i(_hrm->reserved().start()), 2372 p2i(_hrm->reserved().end())); 2373 st->cr(); 2374 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2375 uint young_regions = young_regions_count(); 2376 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2377 (size_t) young_regions * HeapRegion::GrainBytes / K); 2378 uint survivor_regions = survivor_regions_count(); 2379 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2380 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2381 st->cr(); 2382 MetaspaceUtils::print_on(st); 2383 } 2384 2385 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2386 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2387 "HS=humongous(starts), HC=humongous(continues), " 2388 "CS=collection set, F=free, A=archive, " 2389 "TAMS=top-at-mark-start (previous, next)"); 2390 PrintRegionClosure blk(st); 2391 heap_region_iterate(&blk); 2392 } 2393 2394 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2395 print_on(st); 2396 2397 // Print the per-region information. 2398 print_regions_on(st); 2399 } 2400 2401 void G1CollectedHeap::print_on_error(outputStream* st) const { 2402 this->CollectedHeap::print_on_error(st); 2403 2404 if (_cm != NULL) { 2405 st->cr(); 2406 _cm->print_on_error(st); 2407 } 2408 } 2409 2410 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2411 workers()->print_worker_threads_on(st); 2412 _cm_thread->print_on(st); 2413 st->cr(); 2414 _cm->print_worker_threads_on(st); 2415 _cr->print_threads_on(st); 2416 _young_gen_sampling_thread->print_on(st); 2417 if (G1StringDedup::is_enabled()) { 2418 G1StringDedup::print_worker_threads_on(st); 2419 } 2420 } 2421 2422 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2423 workers()->threads_do(tc); 2424 tc->do_thread(_cm_thread); 2425 _cm->threads_do(tc); 2426 _cr->threads_do(tc); 2427 tc->do_thread(_young_gen_sampling_thread); 2428 if (G1StringDedup::is_enabled()) { 2429 G1StringDedup::threads_do(tc); 2430 } 2431 } 2432 2433 void G1CollectedHeap::print_tracing_info() const { 2434 rem_set()->print_summary_info(); 2435 concurrent_mark()->print_summary_info(); 2436 } 2437 2438 #ifndef PRODUCT 2439 // Helpful for debugging RSet issues. 2440 2441 class PrintRSetsClosure : public HeapRegionClosure { 2442 private: 2443 const char* _msg; 2444 size_t _occupied_sum; 2445 2446 public: 2447 bool do_heap_region(HeapRegion* r) { 2448 HeapRegionRemSet* hrrs = r->rem_set(); 2449 size_t occupied = hrrs->occupied(); 2450 _occupied_sum += occupied; 2451 2452 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2453 if (occupied == 0) { 2454 tty->print_cr(" RSet is empty"); 2455 } else { 2456 hrrs->print(); 2457 } 2458 tty->print_cr("----------"); 2459 return false; 2460 } 2461 2462 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2463 tty->cr(); 2464 tty->print_cr("========================================"); 2465 tty->print_cr("%s", msg); 2466 tty->cr(); 2467 } 2468 2469 ~PrintRSetsClosure() { 2470 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2471 tty->print_cr("========================================"); 2472 tty->cr(); 2473 } 2474 }; 2475 2476 void G1CollectedHeap::print_cset_rsets() { 2477 PrintRSetsClosure cl("Printing CSet RSets"); 2478 collection_set_iterate_all(&cl); 2479 } 2480 2481 void G1CollectedHeap::print_all_rsets() { 2482 PrintRSetsClosure cl("Printing All RSets");; 2483 heap_region_iterate(&cl); 2484 } 2485 #endif // PRODUCT 2486 2487 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2488 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2489 } 2490 2491 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2492 2493 size_t eden_used_bytes = _eden.used_bytes(); 2494 size_t survivor_used_bytes = _survivor.used_bytes(); 2495 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2496 2497 size_t eden_capacity_bytes = 2498 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2499 2500 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2501 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2502 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2503 } 2504 2505 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2506 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2507 stats->unused(), stats->used(), stats->region_end_waste(), 2508 stats->regions_filled(), stats->direct_allocated(), 2509 stats->failure_used(), stats->failure_waste()); 2510 } 2511 2512 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2513 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2514 gc_tracer->report_gc_heap_summary(when, heap_summary); 2515 2516 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2517 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2518 } 2519 2520 G1CollectedHeap* G1CollectedHeap::heap() { 2521 CollectedHeap* heap = Universe::heap(); 2522 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2523 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2524 return (G1CollectedHeap*)heap; 2525 } 2526 2527 void G1CollectedHeap::gc_prologue(bool full) { 2528 // always_do_update_barrier = false; 2529 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2530 2531 // This summary needs to be printed before incrementing total collections. 2532 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2533 2534 // Update common counters. 2535 increment_total_collections(full /* full gc */); 2536 if (full || collector_state()->in_initial_mark_gc()) { 2537 increment_old_marking_cycles_started(); 2538 } 2539 2540 // Fill TLAB's and such 2541 double start = os::elapsedTime(); 2542 ensure_parsability(true); 2543 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2544 } 2545 2546 void G1CollectedHeap::gc_epilogue(bool full) { 2547 // Update common counters. 2548 if (full) { 2549 // Update the number of full collections that have been completed. 2550 increment_old_marking_cycles_completed(false /* concurrent */); 2551 } 2552 2553 // We are at the end of the GC. Total collections has already been increased. 2554 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2555 2556 // FIXME: what is this about? 2557 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2558 // is set. 2559 #if COMPILER2_OR_JVMCI 2560 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2561 #endif 2562 // always_do_update_barrier = true; 2563 2564 double start = os::elapsedTime(); 2565 resize_all_tlabs(); 2566 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2567 2568 MemoryService::track_memory_usage(); 2569 // We have just completed a GC. Update the soft reference 2570 // policy with the new heap occupancy 2571 Universe::update_heap_info_at_gc(); 2572 } 2573 2574 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2575 uint gc_count_before, 2576 bool* succeeded, 2577 GCCause::Cause gc_cause) { 2578 assert_heap_not_locked_and_not_at_safepoint(); 2579 VM_G1CollectForAllocation op(word_size, 2580 gc_count_before, 2581 gc_cause, 2582 false, /* should_initiate_conc_mark */ 2583 policy()->max_pause_time_ms()); 2584 VMThread::execute(&op); 2585 2586 HeapWord* result = op.result(); 2587 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2588 assert(result == NULL || ret_succeeded, 2589 "the result should be NULL if the VM did not succeed"); 2590 *succeeded = ret_succeeded; 2591 2592 assert_heap_not_locked(); 2593 return result; 2594 } 2595 2596 void G1CollectedHeap::do_concurrent_mark() { 2597 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2598 if (!_cm_thread->in_progress()) { 2599 _cm_thread->set_started(); 2600 CGC_lock->notify(); 2601 } 2602 } 2603 2604 size_t G1CollectedHeap::pending_card_num() { 2605 struct CountCardsClosure : public ThreadClosure { 2606 size_t _cards; 2607 CountCardsClosure() : _cards(0) {} 2608 virtual void do_thread(Thread* t) { 2609 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2610 } 2611 } count_from_threads; 2612 Threads::threads_do(&count_from_threads); 2613 2614 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2615 dcqs.verify_num_cards(); 2616 2617 return dcqs.num_cards() + count_from_threads._cards; 2618 } 2619 2620 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2621 // We don't nominate objects with many remembered set entries, on 2622 // the assumption that such objects are likely still live. 2623 HeapRegionRemSet* rem_set = r->rem_set(); 2624 2625 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2626 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2627 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2628 } 2629 2630 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2631 private: 2632 size_t _total_humongous; 2633 size_t _candidate_humongous; 2634 2635 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2636 assert(region->is_starts_humongous(), "Must start a humongous object"); 2637 2638 oop obj = oop(region->bottom()); 2639 2640 // Dead objects cannot be eager reclaim candidates. Due to class 2641 // unloading it is unsafe to query their classes so we return early. 2642 if (g1h->is_obj_dead(obj, region)) { 2643 return false; 2644 } 2645 2646 // If we do not have a complete remembered set for the region, then we can 2647 // not be sure that we have all references to it. 2648 if (!region->rem_set()->is_complete()) { 2649 return false; 2650 } 2651 // Candidate selection must satisfy the following constraints 2652 // while concurrent marking is in progress: 2653 // 2654 // * In order to maintain SATB invariants, an object must not be 2655 // reclaimed if it was allocated before the start of marking and 2656 // has not had its references scanned. Such an object must have 2657 // its references (including type metadata) scanned to ensure no 2658 // live objects are missed by the marking process. Objects 2659 // allocated after the start of concurrent marking don't need to 2660 // be scanned. 2661 // 2662 // * An object must not be reclaimed if it is on the concurrent 2663 // mark stack. Objects allocated after the start of concurrent 2664 // marking are never pushed on the mark stack. 2665 // 2666 // Nominating only objects allocated after the start of concurrent 2667 // marking is sufficient to meet both constraints. This may miss 2668 // some objects that satisfy the constraints, but the marking data 2669 // structures don't support efficiently performing the needed 2670 // additional tests or scrubbing of the mark stack. 2671 // 2672 // However, we presently only nominate is_typeArray() objects. 2673 // A humongous object containing references induces remembered 2674 // set entries on other regions. In order to reclaim such an 2675 // object, those remembered sets would need to be cleaned up. 2676 // 2677 // We also treat is_typeArray() objects specially, allowing them 2678 // to be reclaimed even if allocated before the start of 2679 // concurrent mark. For this we rely on mark stack insertion to 2680 // exclude is_typeArray() objects, preventing reclaiming an object 2681 // that is in the mark stack. We also rely on the metadata for 2682 // such objects to be built-in and so ensured to be kept live. 2683 // Frequent allocation and drop of large binary blobs is an 2684 // important use case for eager reclaim, and this special handling 2685 // may reduce needed headroom. 2686 2687 return obj->is_typeArray() && 2688 g1h->is_potential_eager_reclaim_candidate(region); 2689 } 2690 2691 public: 2692 RegisterRegionsWithRegionAttrTableClosure() 2693 : _total_humongous(0), 2694 _candidate_humongous(0) { 2695 } 2696 2697 virtual bool do_heap_region(HeapRegion* r) { 2698 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2699 2700 if (!r->is_starts_humongous()) { 2701 g1h->register_region_with_region_attr(r); 2702 return false; 2703 } 2704 2705 bool is_candidate = humongous_region_is_candidate(g1h, r); 2706 uint rindex = r->hrm_index(); 2707 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2708 if (is_candidate) { 2709 g1h->register_humongous_region_with_region_attr(rindex); 2710 _candidate_humongous++; 2711 // We will later handle the remembered sets of these regions. 2712 } else { 2713 g1h->register_region_with_region_attr(r); 2714 } 2715 _total_humongous++; 2716 2717 return false; 2718 } 2719 2720 size_t total_humongous() const { return _total_humongous; } 2721 size_t candidate_humongous() const { return _candidate_humongous; } 2722 }; 2723 2724 void G1CollectedHeap::register_regions_with_region_attr() { 2725 Ticks start = Ticks::now(); 2726 2727 RegisterRegionsWithRegionAttrTableClosure cl; 2728 heap_region_iterate(&cl); 2729 2730 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2731 cl.total_humongous(), 2732 cl.candidate_humongous()); 2733 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2734 } 2735 2736 #ifndef PRODUCT 2737 void G1CollectedHeap::verify_region_attr_remset_update() { 2738 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2739 public: 2740 virtual bool do_heap_region(HeapRegion* r) { 2741 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2742 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2743 assert(r->rem_set()->is_tracked() == needs_remset_update, 2744 "Region %u remset tracking status (%s) different to region attribute (%s)", 2745 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2746 return false; 2747 } 2748 } cl; 2749 heap_region_iterate(&cl); 2750 } 2751 #endif 2752 2753 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2754 public: 2755 bool do_heap_region(HeapRegion* hr) { 2756 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2757 hr->verify_rem_set(); 2758 } 2759 return false; 2760 } 2761 }; 2762 2763 uint G1CollectedHeap::num_task_queues() const { 2764 return _task_queues->size(); 2765 } 2766 2767 #if TASKQUEUE_STATS 2768 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2769 st->print_raw_cr("GC Task Stats"); 2770 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2771 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2772 } 2773 2774 void G1CollectedHeap::print_taskqueue_stats() const { 2775 if (!log_is_enabled(Trace, gc, task, stats)) { 2776 return; 2777 } 2778 Log(gc, task, stats) log; 2779 ResourceMark rm; 2780 LogStream ls(log.trace()); 2781 outputStream* st = &ls; 2782 2783 print_taskqueue_stats_hdr(st); 2784 2785 TaskQueueStats totals; 2786 const uint n = num_task_queues(); 2787 for (uint i = 0; i < n; ++i) { 2788 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2789 totals += task_queue(i)->stats; 2790 } 2791 st->print_raw("tot "); totals.print(st); st->cr(); 2792 2793 DEBUG_ONLY(totals.verify()); 2794 } 2795 2796 void G1CollectedHeap::reset_taskqueue_stats() { 2797 const uint n = num_task_queues(); 2798 for (uint i = 0; i < n; ++i) { 2799 task_queue(i)->stats.reset(); 2800 } 2801 } 2802 #endif // TASKQUEUE_STATS 2803 2804 void G1CollectedHeap::wait_for_root_region_scanning() { 2805 double scan_wait_start = os::elapsedTime(); 2806 // We have to wait until the CM threads finish scanning the 2807 // root regions as it's the only way to ensure that all the 2808 // objects on them have been correctly scanned before we start 2809 // moving them during the GC. 2810 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2811 double wait_time_ms = 0.0; 2812 if (waited) { 2813 double scan_wait_end = os::elapsedTime(); 2814 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2815 } 2816 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2817 } 2818 2819 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2820 private: 2821 G1HRPrinter* _hr_printer; 2822 public: 2823 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2824 2825 virtual bool do_heap_region(HeapRegion* r) { 2826 _hr_printer->cset(r); 2827 return false; 2828 } 2829 }; 2830 2831 void G1CollectedHeap::start_new_collection_set() { 2832 double start = os::elapsedTime(); 2833 2834 collection_set()->start_incremental_building(); 2835 2836 clear_region_attr(); 2837 2838 guarantee(_eden.length() == 0, "eden should have been cleared"); 2839 policy()->transfer_survivors_to_cset(survivor()); 2840 2841 // We redo the verification but now wrt to the new CSet which 2842 // has just got initialized after the previous CSet was freed. 2843 _cm->verify_no_collection_set_oops(); 2844 2845 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2846 } 2847 2848 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2849 2850 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2851 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2852 collection_set()->optional_region_length()); 2853 2854 _cm->verify_no_collection_set_oops(); 2855 2856 if (_hr_printer.is_active()) { 2857 G1PrintCollectionSetClosure cl(&_hr_printer); 2858 _collection_set.iterate(&cl); 2859 _collection_set.iterate_optional(&cl); 2860 } 2861 } 2862 2863 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2864 if (collector_state()->in_initial_mark_gc()) { 2865 return G1HeapVerifier::G1VerifyConcurrentStart; 2866 } else if (collector_state()->in_young_only_phase()) { 2867 return G1HeapVerifier::G1VerifyYoungNormal; 2868 } else { 2869 return G1HeapVerifier::G1VerifyMixed; 2870 } 2871 } 2872 2873 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2874 if (VerifyRememberedSets) { 2875 log_info(gc, verify)("[Verifying RemSets before GC]"); 2876 VerifyRegionRemSetClosure v_cl; 2877 heap_region_iterate(&v_cl); 2878 } 2879 _verifier->verify_before_gc(type); 2880 _verifier->check_bitmaps("GC Start"); 2881 } 2882 2883 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2884 if (VerifyRememberedSets) { 2885 log_info(gc, verify)("[Verifying RemSets after GC]"); 2886 VerifyRegionRemSetClosure v_cl; 2887 heap_region_iterate(&v_cl); 2888 } 2889 _verifier->verify_after_gc(type); 2890 _verifier->check_bitmaps("GC End"); 2891 } 2892 2893 void G1CollectedHeap::expand_heap_after_young_collection(){ 2894 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2895 if (expand_bytes > 0) { 2896 // No need for an ergo logging here, 2897 // expansion_amount() does this when it returns a value > 0. 2898 double expand_ms; 2899 if (!expand(expand_bytes, _workers, &expand_ms)) { 2900 // We failed to expand the heap. Cannot do anything about it. 2901 } 2902 phase_times()->record_expand_heap_time(expand_ms); 2903 } 2904 } 2905 2906 const char* G1CollectedHeap::young_gc_name() const { 2907 if (collector_state()->in_initial_mark_gc()) { 2908 return "Pause Young (Concurrent Start)"; 2909 } else if (collector_state()->in_young_only_phase()) { 2910 if (collector_state()->in_young_gc_before_mixed()) { 2911 return "Pause Young (Prepare Mixed)"; 2912 } else { 2913 return "Pause Young (Normal)"; 2914 } 2915 } else { 2916 return "Pause Young (Mixed)"; 2917 } 2918 } 2919 2920 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2921 assert_at_safepoint_on_vm_thread(); 2922 guarantee(!is_gc_active(), "collection is not reentrant"); 2923 2924 if (GCLocker::check_active_before_gc()) { 2925 return false; 2926 } 2927 2928 GCIdMark gc_id_mark; 2929 2930 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2931 ResourceMark rm; 2932 2933 policy()->note_gc_start(); 2934 2935 _gc_timer_stw->register_gc_start(); 2936 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2937 2938 wait_for_root_region_scanning(); 2939 2940 print_heap_before_gc(); 2941 print_heap_regions(); 2942 trace_heap_before_gc(_gc_tracer_stw); 2943 2944 _verifier->verify_region_sets_optional(); 2945 _verifier->verify_dirty_young_regions(); 2946 2947 // We should not be doing initial mark unless the conc mark thread is running 2948 if (!_cm_thread->should_terminate()) { 2949 // This call will decide whether this pause is an initial-mark 2950 // pause. If it is, in_initial_mark_gc() will return true 2951 // for the duration of this pause. 2952 policy()->decide_on_conc_mark_initiation(); 2953 } 2954 2955 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2956 assert(!collector_state()->in_initial_mark_gc() || 2957 collector_state()->in_young_only_phase(), "sanity"); 2958 // We also do not allow mixed GCs during marking. 2959 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2960 2961 // Record whether this pause is an initial mark. When the current 2962 // thread has completed its logging output and it's safe to signal 2963 // the CM thread, the flag's value in the policy has been reset. 2964 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2965 if (should_start_conc_mark) { 2966 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2967 } 2968 2969 // Inner scope for scope based logging, timers, and stats collection 2970 { 2971 G1EvacuationInfo evacuation_info; 2972 2973 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2974 2975 GCTraceCPUTime tcpu; 2976 2977 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 2978 2979 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2980 workers()->active_workers(), 2981 Threads::number_of_non_daemon_threads()); 2982 active_workers = workers()->update_active_workers(active_workers); 2983 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2984 2985 G1MonitoringScope ms(g1mm(), 2986 false /* full_gc */, 2987 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2988 2989 G1HeapTransition heap_transition(this); 2990 size_t heap_used_bytes_before_gc = used(); 2991 2992 { 2993 IsGCActiveMark x; 2994 2995 gc_prologue(false); 2996 2997 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 2998 verify_before_young_collection(verify_type); 2999 3000 { 3001 // The elapsed time induced by the start time below deliberately elides 3002 // the possible verification above. 3003 double sample_start_time_sec = os::elapsedTime(); 3004 3005 // Please see comment in g1CollectedHeap.hpp and 3006 // G1CollectedHeap::ref_processing_init() to see how 3007 // reference processing currently works in G1. 3008 _ref_processor_stw->enable_discovery(); 3009 3010 // We want to temporarily turn off discovery by the 3011 // CM ref processor, if necessary, and turn it back on 3012 // on again later if we do. Using a scoped 3013 // NoRefDiscovery object will do this. 3014 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3015 3016 policy()->record_collection_pause_start(sample_start_time_sec); 3017 3018 // Forget the current allocation region (we might even choose it to be part 3019 // of the collection set!). 3020 _allocator->release_mutator_alloc_region(); 3021 3022 calculate_collection_set(evacuation_info, target_pause_time_ms); 3023 3024 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3025 G1ParScanThreadStateSet per_thread_states(this, 3026 &rdcqs, 3027 workers()->active_workers(), 3028 collection_set()->young_region_length(), 3029 collection_set()->optional_region_length()); 3030 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3031 3032 // Actually do the work... 3033 evacuate_initial_collection_set(&per_thread_states); 3034 3035 if (_collection_set.optional_region_length() != 0) { 3036 evacuate_optional_collection_set(&per_thread_states); 3037 } 3038 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3039 3040 start_new_collection_set(); 3041 3042 _survivor_evac_stats.adjust_desired_plab_sz(); 3043 _old_evac_stats.adjust_desired_plab_sz(); 3044 3045 if (should_start_conc_mark) { 3046 // We have to do this before we notify the CM threads that 3047 // they can start working to make sure that all the 3048 // appropriate initialization is done on the CM object. 3049 concurrent_mark()->post_initial_mark(); 3050 // Note that we don't actually trigger the CM thread at 3051 // this point. We do that later when we're sure that 3052 // the current thread has completed its logging output. 3053 } 3054 3055 allocate_dummy_regions(); 3056 3057 _allocator->init_mutator_alloc_region(); 3058 3059 expand_heap_after_young_collection(); 3060 3061 double sample_end_time_sec = os::elapsedTime(); 3062 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3063 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc); 3064 } 3065 3066 verify_after_young_collection(verify_type); 3067 3068 #ifdef TRACESPINNING 3069 ParallelTaskTerminator::print_termination_counts(); 3070 #endif 3071 3072 gc_epilogue(false); 3073 } 3074 3075 // Print the remainder of the GC log output. 3076 if (evacuation_failed()) { 3077 log_info(gc)("To-space exhausted"); 3078 } 3079 3080 policy()->print_phases(); 3081 heap_transition.print(); 3082 3083 _hrm->verify_optional(); 3084 _verifier->verify_region_sets_optional(); 3085 3086 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3087 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3088 3089 print_heap_after_gc(); 3090 print_heap_regions(); 3091 trace_heap_after_gc(_gc_tracer_stw); 3092 3093 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3094 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3095 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3096 // before any GC notifications are raised. 3097 g1mm()->update_sizes(); 3098 3099 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3100 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3101 _gc_timer_stw->register_gc_end(); 3102 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3103 } 3104 // It should now be safe to tell the concurrent mark thread to start 3105 // without its logging output interfering with the logging output 3106 // that came from the pause. 3107 3108 if (should_start_conc_mark) { 3109 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3110 // thread(s) could be running concurrently with us. Make sure that anything 3111 // after this point does not assume that we are the only GC thread running. 3112 // Note: of course, the actual marking work will not start until the safepoint 3113 // itself is released in SuspendibleThreadSet::desynchronize(). 3114 do_concurrent_mark(); 3115 } 3116 3117 return true; 3118 } 3119 3120 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3121 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3122 workers()->run_task(&rsfp_task); 3123 } 3124 3125 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3126 double remove_self_forwards_start = os::elapsedTime(); 3127 3128 remove_self_forwarding_pointers(rdcqs); 3129 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3130 _preserved_marks_set.restore(&task_executor); 3131 3132 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3133 } 3134 3135 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3136 if (!_evacuation_failed) { 3137 _evacuation_failed = true; 3138 } 3139 3140 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3141 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3142 } 3143 3144 bool G1ParEvacuateFollowersClosure::offer_termination() { 3145 EventGCPhaseParallel event; 3146 G1ParScanThreadState* const pss = par_scan_state(); 3147 start_term_time(); 3148 const bool res = terminator()->offer_termination(); 3149 end_term_time(); 3150 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3151 return res; 3152 } 3153 3154 void G1ParEvacuateFollowersClosure::do_void() { 3155 EventGCPhaseParallel event; 3156 G1ParScanThreadState* const pss = par_scan_state(); 3157 pss->trim_queue(); 3158 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3159 do { 3160 EventGCPhaseParallel event; 3161 pss->steal_and_trim_queue(queues()); 3162 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3163 } while (!offer_termination()); 3164 } 3165 3166 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3167 bool class_unloading_occurred) { 3168 uint num_workers = workers()->active_workers(); 3169 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3170 workers()->run_task(&unlink_task); 3171 } 3172 3173 // Clean string dedup data structures. 3174 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3175 // record the durations of the phases. Hence the almost-copy. 3176 class G1StringDedupCleaningTask : public AbstractGangTask { 3177 BoolObjectClosure* _is_alive; 3178 OopClosure* _keep_alive; 3179 G1GCPhaseTimes* _phase_times; 3180 3181 public: 3182 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3183 OopClosure* keep_alive, 3184 G1GCPhaseTimes* phase_times) : 3185 AbstractGangTask("Partial Cleaning Task"), 3186 _is_alive(is_alive), 3187 _keep_alive(keep_alive), 3188 _phase_times(phase_times) 3189 { 3190 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3191 StringDedup::gc_prologue(true); 3192 } 3193 3194 ~G1StringDedupCleaningTask() { 3195 StringDedup::gc_epilogue(); 3196 } 3197 3198 void work(uint worker_id) { 3199 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3200 { 3201 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3202 StringDedupQueue::unlink_or_oops_do(&cl); 3203 } 3204 { 3205 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3206 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3207 } 3208 } 3209 }; 3210 3211 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3212 OopClosure* keep_alive, 3213 G1GCPhaseTimes* phase_times) { 3214 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3215 workers()->run_task(&cl); 3216 } 3217 3218 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3219 private: 3220 G1RedirtyCardsQueueSet* _qset; 3221 G1CollectedHeap* _g1h; 3222 BufferNode* volatile _nodes; 3223 3224 void apply(G1CardTableEntryClosure* cl, BufferNode* node, uint worker_id) { 3225 void** buf = BufferNode::make_buffer_from_node(node); 3226 size_t limit = _qset->buffer_size(); 3227 for (size_t i = node->index(); i < limit; ++i) { 3228 CardTable::CardValue* card_ptr = static_cast<CardTable::CardValue*>(buf[i]); 3229 bool result = cl->do_card_ptr(card_ptr, worker_id); 3230 assert(result, "Closure should always return true"); 3231 } 3232 } 3233 3234 void par_apply(G1CardTableEntryClosure* cl, uint worker_id) { 3235 BufferNode* next = Atomic::load(&_nodes); 3236 while (next != NULL) { 3237 BufferNode* node = next; 3238 next = Atomic::cmpxchg(node->next(), &_nodes, node); 3239 if (next == node) { 3240 apply(cl, node, worker_id); 3241 next = node->next(); 3242 } 3243 } 3244 } 3245 3246 public: 3247 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3248 AbstractGangTask("Redirty Cards"), 3249 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3250 3251 virtual void work(uint worker_id) { 3252 G1GCPhaseTimes* p = _g1h->phase_times(); 3253 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3254 3255 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3256 par_apply(&cl, worker_id); 3257 3258 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3259 } 3260 }; 3261 3262 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3263 double redirty_logged_cards_start = os::elapsedTime(); 3264 3265 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3266 workers()->run_task(&redirty_task); 3267 3268 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3269 dcq.merge_bufferlists(rdcqs); 3270 3271 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3272 } 3273 3274 // Weak Reference Processing support 3275 3276 bool G1STWIsAliveClosure::do_object_b(oop p) { 3277 // An object is reachable if it is outside the collection set, 3278 // or is inside and copied. 3279 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3280 } 3281 3282 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3283 assert(obj != NULL, "must not be NULL"); 3284 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3285 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3286 // may falsely indicate that this is not the case here: however the collection set only 3287 // contains old regions when concurrent mark is not running. 3288 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3289 } 3290 3291 // Non Copying Keep Alive closure 3292 class G1KeepAliveClosure: public OopClosure { 3293 G1CollectedHeap*_g1h; 3294 public: 3295 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3296 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3297 void do_oop(oop* p) { 3298 oop obj = *p; 3299 assert(obj != NULL, "the caller should have filtered out NULL values"); 3300 3301 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3302 if (!region_attr.is_in_cset_or_humongous()) { 3303 return; 3304 } 3305 if (region_attr.is_in_cset()) { 3306 assert( obj->is_forwarded(), "invariant" ); 3307 *p = obj->forwardee(); 3308 } else { 3309 assert(!obj->is_forwarded(), "invariant" ); 3310 assert(region_attr.is_humongous(), 3311 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3312 _g1h->set_humongous_is_live(obj); 3313 } 3314 } 3315 }; 3316 3317 // Copying Keep Alive closure - can be called from both 3318 // serial and parallel code as long as different worker 3319 // threads utilize different G1ParScanThreadState instances 3320 // and different queues. 3321 3322 class G1CopyingKeepAliveClosure: public OopClosure { 3323 G1CollectedHeap* _g1h; 3324 G1ParScanThreadState* _par_scan_state; 3325 3326 public: 3327 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3328 G1ParScanThreadState* pss): 3329 _g1h(g1h), 3330 _par_scan_state(pss) 3331 {} 3332 3333 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3334 virtual void do_oop( oop* p) { do_oop_work(p); } 3335 3336 template <class T> void do_oop_work(T* p) { 3337 oop obj = RawAccess<>::oop_load(p); 3338 3339 if (_g1h->is_in_cset_or_humongous(obj)) { 3340 // If the referent object has been forwarded (either copied 3341 // to a new location or to itself in the event of an 3342 // evacuation failure) then we need to update the reference 3343 // field and, if both reference and referent are in the G1 3344 // heap, update the RSet for the referent. 3345 // 3346 // If the referent has not been forwarded then we have to keep 3347 // it alive by policy. Therefore we have copy the referent. 3348 // 3349 // When the queue is drained (after each phase of reference processing) 3350 // the object and it's followers will be copied, the reference field set 3351 // to point to the new location, and the RSet updated. 3352 _par_scan_state->push_on_queue(p); 3353 } 3354 } 3355 }; 3356 3357 // Serial drain queue closure. Called as the 'complete_gc' 3358 // closure for each discovered list in some of the 3359 // reference processing phases. 3360 3361 class G1STWDrainQueueClosure: public VoidClosure { 3362 protected: 3363 G1CollectedHeap* _g1h; 3364 G1ParScanThreadState* _par_scan_state; 3365 3366 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3367 3368 public: 3369 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3370 _g1h(g1h), 3371 _par_scan_state(pss) 3372 { } 3373 3374 void do_void() { 3375 G1ParScanThreadState* const pss = par_scan_state(); 3376 pss->trim_queue(); 3377 } 3378 }; 3379 3380 // Parallel Reference Processing closures 3381 3382 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3383 // processing during G1 evacuation pauses. 3384 3385 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3386 private: 3387 G1CollectedHeap* _g1h; 3388 G1ParScanThreadStateSet* _pss; 3389 RefToScanQueueSet* _queues; 3390 WorkGang* _workers; 3391 3392 public: 3393 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3394 G1ParScanThreadStateSet* per_thread_states, 3395 WorkGang* workers, 3396 RefToScanQueueSet *task_queues) : 3397 _g1h(g1h), 3398 _pss(per_thread_states), 3399 _queues(task_queues), 3400 _workers(workers) 3401 { 3402 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3403 } 3404 3405 // Executes the given task using concurrent marking worker threads. 3406 virtual void execute(ProcessTask& task, uint ergo_workers); 3407 }; 3408 3409 // Gang task for possibly parallel reference processing 3410 3411 class G1STWRefProcTaskProxy: public AbstractGangTask { 3412 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3413 ProcessTask& _proc_task; 3414 G1CollectedHeap* _g1h; 3415 G1ParScanThreadStateSet* _pss; 3416 RefToScanQueueSet* _task_queues; 3417 ParallelTaskTerminator* _terminator; 3418 3419 public: 3420 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3421 G1CollectedHeap* g1h, 3422 G1ParScanThreadStateSet* per_thread_states, 3423 RefToScanQueueSet *task_queues, 3424 ParallelTaskTerminator* terminator) : 3425 AbstractGangTask("Process reference objects in parallel"), 3426 _proc_task(proc_task), 3427 _g1h(g1h), 3428 _pss(per_thread_states), 3429 _task_queues(task_queues), 3430 _terminator(terminator) 3431 {} 3432 3433 virtual void work(uint worker_id) { 3434 // The reference processing task executed by a single worker. 3435 ResourceMark rm; 3436 HandleMark hm; 3437 3438 G1STWIsAliveClosure is_alive(_g1h); 3439 3440 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3441 pss->set_ref_discoverer(NULL); 3442 3443 // Keep alive closure. 3444 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3445 3446 // Complete GC closure 3447 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3448 3449 // Call the reference processing task's work routine. 3450 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3451 3452 // Note we cannot assert that the refs array is empty here as not all 3453 // of the processing tasks (specifically phase2 - pp2_work) execute 3454 // the complete_gc closure (which ordinarily would drain the queue) so 3455 // the queue may not be empty. 3456 } 3457 }; 3458 3459 // Driver routine for parallel reference processing. 3460 // Creates an instance of the ref processing gang 3461 // task and has the worker threads execute it. 3462 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3463 assert(_workers != NULL, "Need parallel worker threads."); 3464 3465 assert(_workers->active_workers() >= ergo_workers, 3466 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3467 ergo_workers, _workers->active_workers()); 3468 TaskTerminator terminator(ergo_workers, _queues); 3469 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3470 3471 _workers->run_task(&proc_task_proxy, ergo_workers); 3472 } 3473 3474 // End of weak reference support closures 3475 3476 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3477 double ref_proc_start = os::elapsedTime(); 3478 3479 ReferenceProcessor* rp = _ref_processor_stw; 3480 assert(rp->discovery_enabled(), "should have been enabled"); 3481 3482 // Closure to test whether a referent is alive. 3483 G1STWIsAliveClosure is_alive(this); 3484 3485 // Even when parallel reference processing is enabled, the processing 3486 // of JNI refs is serial and performed serially by the current thread 3487 // rather than by a worker. The following PSS will be used for processing 3488 // JNI refs. 3489 3490 // Use only a single queue for this PSS. 3491 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3492 pss->set_ref_discoverer(NULL); 3493 assert(pss->queue_is_empty(), "pre-condition"); 3494 3495 // Keep alive closure. 3496 G1CopyingKeepAliveClosure keep_alive(this, pss); 3497 3498 // Serial Complete GC closure 3499 G1STWDrainQueueClosure drain_queue(this, pss); 3500 3501 // Setup the soft refs policy... 3502 rp->setup_policy(false); 3503 3504 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3505 3506 ReferenceProcessorStats stats; 3507 if (!rp->processing_is_mt()) { 3508 // Serial reference processing... 3509 stats = rp->process_discovered_references(&is_alive, 3510 &keep_alive, 3511 &drain_queue, 3512 NULL, 3513 pt); 3514 } else { 3515 uint no_of_gc_workers = workers()->active_workers(); 3516 3517 // Parallel reference processing 3518 assert(no_of_gc_workers <= rp->max_num_queues(), 3519 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3520 no_of_gc_workers, rp->max_num_queues()); 3521 3522 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3523 stats = rp->process_discovered_references(&is_alive, 3524 &keep_alive, 3525 &drain_queue, 3526 &par_task_executor, 3527 pt); 3528 } 3529 3530 _gc_tracer_stw->report_gc_reference_stats(stats); 3531 3532 // We have completed copying any necessary live referent objects. 3533 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3534 3535 make_pending_list_reachable(); 3536 3537 assert(!rp->discovery_enabled(), "Postcondition"); 3538 rp->verify_no_references_recorded(); 3539 3540 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3541 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3542 } 3543 3544 void G1CollectedHeap::make_pending_list_reachable() { 3545 if (collector_state()->in_initial_mark_gc()) { 3546 oop pll_head = Universe::reference_pending_list(); 3547 if (pll_head != NULL) { 3548 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3549 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3550 } 3551 } 3552 } 3553 3554 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3555 double merge_pss_time_start = os::elapsedTime(); 3556 per_thread_states->flush(); 3557 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3558 } 3559 3560 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3561 _expand_heap_after_alloc_failure = true; 3562 _evacuation_failed = false; 3563 3564 // Disable the hot card cache. 3565 _hot_card_cache->reset_hot_cache_claimed_index(); 3566 _hot_card_cache->set_use_cache(false); 3567 3568 // Initialize the GC alloc regions. 3569 _allocator->init_gc_alloc_regions(evacuation_info); 3570 3571 { 3572 Ticks start = Ticks::now(); 3573 rem_set()->prepare_for_scan_heap_roots(); 3574 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3575 } 3576 3577 register_regions_with_region_attr(); 3578 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3579 3580 _preserved_marks_set.assert_empty(); 3581 3582 #if COMPILER2_OR_JVMCI 3583 DerivedPointerTable::clear(); 3584 #endif 3585 3586 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3587 if (collector_state()->in_initial_mark_gc()) { 3588 concurrent_mark()->pre_initial_mark(); 3589 3590 double start_clear_claimed_marks = os::elapsedTime(); 3591 3592 ClassLoaderDataGraph::clear_claimed_marks(); 3593 3594 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3595 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3596 } 3597 3598 // Should G1EvacuationFailureALot be in effect for this GC? 3599 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3600 } 3601 3602 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3603 protected: 3604 G1CollectedHeap* _g1h; 3605 G1ParScanThreadStateSet* _per_thread_states; 3606 RefToScanQueueSet* _task_queues; 3607 TaskTerminator _terminator; 3608 uint _num_workers; 3609 3610 void evacuate_live_objects(G1ParScanThreadState* pss, 3611 uint worker_id, 3612 G1GCPhaseTimes::GCParPhases objcopy_phase, 3613 G1GCPhaseTimes::GCParPhases termination_phase) { 3614 G1GCPhaseTimes* p = _g1h->phase_times(); 3615 3616 Ticks start = Ticks::now(); 3617 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase); 3618 cl.do_void(); 3619 3620 assert(pss->queue_is_empty(), "should be empty"); 3621 3622 Tickspan evac_time = (Ticks::now() - start); 3623 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3624 3625 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste); 3626 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste); 3627 3628 if (termination_phase == G1GCPhaseTimes::Termination) { 3629 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3630 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3631 } else { 3632 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3633 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3634 } 3635 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3636 } 3637 3638 virtual void start_work(uint worker_id) { } 3639 3640 virtual void end_work(uint worker_id) { } 3641 3642 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3643 3644 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3645 3646 public: 3647 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3648 AbstractGangTask(name), 3649 _g1h(G1CollectedHeap::heap()), 3650 _per_thread_states(per_thread_states), 3651 _task_queues(task_queues), 3652 _terminator(num_workers, _task_queues), 3653 _num_workers(num_workers) 3654 { } 3655 3656 void work(uint worker_id) { 3657 start_work(worker_id); 3658 3659 { 3660 ResourceMark rm; 3661 HandleMark hm; 3662 3663 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3664 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3665 3666 scan_roots(pss, worker_id); 3667 evacuate_live_objects(pss, worker_id); 3668 } 3669 3670 end_work(worker_id); 3671 } 3672 }; 3673 3674 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3675 G1RootProcessor* _root_processor; 3676 3677 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3678 _root_processor->evacuate_roots(pss, worker_id); 3679 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3680 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3681 } 3682 3683 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3684 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3685 } 3686 3687 void start_work(uint worker_id) { 3688 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3689 } 3690 3691 void end_work(uint worker_id) { 3692 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3693 } 3694 3695 public: 3696 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3697 G1ParScanThreadStateSet* per_thread_states, 3698 RefToScanQueueSet* task_queues, 3699 G1RootProcessor* root_processor, 3700 uint num_workers) : 3701 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3702 _root_processor(root_processor) 3703 { } 3704 }; 3705 3706 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3707 G1GCPhaseTimes* p = phase_times(); 3708 3709 { 3710 Ticks start = Ticks::now(); 3711 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3712 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3713 } 3714 3715 Tickspan task_time; 3716 const uint num_workers = workers()->active_workers(); 3717 3718 Ticks start_processing = Ticks::now(); 3719 { 3720 G1RootProcessor root_processor(this, num_workers); 3721 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3722 task_time = run_task(&g1_par_task); 3723 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3724 // To extract its code root fixup time we measure total time of this scope and 3725 // subtract from the time the WorkGang task took. 3726 } 3727 Tickspan total_processing = Ticks::now() - start_processing; 3728 3729 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3730 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3731 } 3732 3733 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3734 3735 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3736 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3737 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3738 } 3739 3740 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3741 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3742 } 3743 3744 public: 3745 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3746 RefToScanQueueSet* queues, 3747 uint num_workers) : 3748 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3749 } 3750 }; 3751 3752 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3753 class G1MarkScope : public MarkScope { }; 3754 3755 Tickspan task_time; 3756 3757 Ticks start_processing = Ticks::now(); 3758 { 3759 G1MarkScope code_mark_scope; 3760 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3761 task_time = run_task(&task); 3762 // See comment in evacuate_collection_set() for the reason of the scope. 3763 } 3764 Tickspan total_processing = Ticks::now() - start_processing; 3765 3766 G1GCPhaseTimes* p = phase_times(); 3767 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3768 } 3769 3770 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3771 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3772 3773 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3774 3775 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3776 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3777 3778 if (time_left_ms < 0 || 3779 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3780 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3781 _collection_set.optional_region_length(), time_left_ms); 3782 break; 3783 } 3784 3785 { 3786 Ticks start = Ticks::now(); 3787 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3788 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3789 } 3790 3791 { 3792 Ticks start = Ticks::now(); 3793 evacuate_next_optional_regions(per_thread_states); 3794 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3795 } 3796 } 3797 3798 _collection_set.abandon_optional_collection_set(per_thread_states); 3799 } 3800 3801 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3802 G1RedirtyCardsQueueSet* rdcqs, 3803 G1ParScanThreadStateSet* per_thread_states) { 3804 rem_set()->cleanup_after_scan_heap_roots(); 3805 3806 // Process any discovered reference objects - we have 3807 // to do this _before_ we retire the GC alloc regions 3808 // as we may have to copy some 'reachable' referent 3809 // objects (and their reachable sub-graphs) that were 3810 // not copied during the pause. 3811 process_discovered_references(per_thread_states); 3812 3813 G1STWIsAliveClosure is_alive(this); 3814 G1KeepAliveClosure keep_alive(this); 3815 3816 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3817 phase_times()->weak_phase_times()); 3818 3819 if (G1StringDedup::is_enabled()) { 3820 double string_dedup_time_ms = os::elapsedTime(); 3821 3822 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3823 3824 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3825 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3826 } 3827 3828 _allocator->release_gc_alloc_regions(evacuation_info); 3829 3830 if (evacuation_failed()) { 3831 restore_after_evac_failure(rdcqs); 3832 3833 // Reset the G1EvacuationFailureALot counters and flags 3834 NOT_PRODUCT(reset_evacuation_should_fail();) 3835 3836 double recalculate_used_start = os::elapsedTime(); 3837 set_used(recalculate_used()); 3838 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3839 3840 if (_archive_allocator != NULL) { 3841 _archive_allocator->clear_used(); 3842 } 3843 for (uint i = 0; i < ParallelGCThreads; i++) { 3844 if (_evacuation_failed_info_array[i].has_failed()) { 3845 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3846 } 3847 } 3848 } else { 3849 // The "used" of the the collection set have already been subtracted 3850 // when they were freed. Add in the bytes evacuated. 3851 increase_used(policy()->bytes_copied_during_gc()); 3852 } 3853 3854 _preserved_marks_set.assert_empty(); 3855 3856 merge_per_thread_state_info(per_thread_states); 3857 3858 // Reset and re-enable the hot card cache. 3859 // Note the counts for the cards in the regions in the 3860 // collection set are reset when the collection set is freed. 3861 _hot_card_cache->reset_hot_cache(); 3862 _hot_card_cache->set_use_cache(true); 3863 3864 purge_code_root_memory(); 3865 3866 redirty_logged_cards(rdcqs); 3867 3868 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3869 3870 eagerly_reclaim_humongous_regions(); 3871 3872 record_obj_copy_mem_stats(); 3873 3874 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3875 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3876 3877 #if COMPILER2_OR_JVMCI 3878 double start = os::elapsedTime(); 3879 DerivedPointerTable::update_pointers(); 3880 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3881 #endif 3882 policy()->print_age_table(); 3883 } 3884 3885 void G1CollectedHeap::record_obj_copy_mem_stats() { 3886 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3887 3888 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3889 create_g1_evac_summary(&_old_evac_stats)); 3890 } 3891 3892 void G1CollectedHeap::free_region(HeapRegion* hr, 3893 FreeRegionList* free_list, 3894 bool skip_remset, 3895 bool skip_hot_card_cache, 3896 bool locked) { 3897 assert(!hr->is_free(), "the region should not be free"); 3898 assert(!hr->is_empty(), "the region should not be empty"); 3899 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3900 assert(free_list != NULL, "pre-condition"); 3901 3902 if (G1VerifyBitmaps) { 3903 MemRegion mr(hr->bottom(), hr->end()); 3904 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3905 } 3906 3907 // Clear the card counts for this region. 3908 // Note: we only need to do this if the region is not young 3909 // (since we don't refine cards in young regions). 3910 if (!skip_hot_card_cache && !hr->is_young()) { 3911 _hot_card_cache->reset_card_counts(hr); 3912 } 3913 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3914 _policy->remset_tracker()->update_at_free(hr); 3915 free_list->add_ordered(hr); 3916 } 3917 3918 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3919 FreeRegionList* free_list) { 3920 assert(hr->is_humongous(), "this is only for humongous regions"); 3921 assert(free_list != NULL, "pre-condition"); 3922 hr->clear_humongous(); 3923 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3924 } 3925 3926 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3927 const uint humongous_regions_removed) { 3928 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3929 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3930 _old_set.bulk_remove(old_regions_removed); 3931 _humongous_set.bulk_remove(humongous_regions_removed); 3932 } 3933 3934 } 3935 3936 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3937 assert(list != NULL, "list can't be null"); 3938 if (!list->is_empty()) { 3939 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3940 _hrm->insert_list_into_free_list(list); 3941 } 3942 } 3943 3944 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3945 decrease_used(bytes); 3946 } 3947 3948 class G1FreeCollectionSetTask : public AbstractGangTask { 3949 private: 3950 3951 // Closure applied to all regions in the collection set to do work that needs to 3952 // be done serially in a single thread. 3953 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3954 private: 3955 G1EvacuationInfo* _evacuation_info; 3956 const size_t* _surviving_young_words; 3957 3958 // Bytes used in successfully evacuated regions before the evacuation. 3959 size_t _before_used_bytes; 3960 // Bytes used in unsucessfully evacuated regions before the evacuation 3961 size_t _after_used_bytes; 3962 3963 size_t _bytes_allocated_in_old_since_last_gc; 3964 3965 size_t _failure_used_words; 3966 size_t _failure_waste_words; 3967 3968 FreeRegionList _local_free_list; 3969 public: 3970 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3971 HeapRegionClosure(), 3972 _evacuation_info(evacuation_info), 3973 _surviving_young_words(surviving_young_words), 3974 _before_used_bytes(0), 3975 _after_used_bytes(0), 3976 _bytes_allocated_in_old_since_last_gc(0), 3977 _failure_used_words(0), 3978 _failure_waste_words(0), 3979 _local_free_list("Local Region List for CSet Freeing") { 3980 } 3981 3982 virtual bool do_heap_region(HeapRegion* r) { 3983 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3984 3985 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3986 g1h->clear_region_attr(r); 3987 3988 if (r->is_young()) { 3989 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(), 3990 "Young index %u is wrong for region %u of type %s with %u young regions", 3991 r->young_index_in_cset(), 3992 r->hrm_index(), 3993 r->get_type_str(), 3994 g1h->collection_set()->young_region_length()); 3995 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 3996 r->record_surv_words_in_group(words_survived); 3997 } 3998 3999 if (!r->evacuation_failed()) { 4000 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4001 _before_used_bytes += r->used(); 4002 g1h->free_region(r, 4003 &_local_free_list, 4004 true, /* skip_remset */ 4005 true, /* skip_hot_card_cache */ 4006 true /* locked */); 4007 } else { 4008 r->uninstall_surv_rate_group(); 4009 r->clear_young_index_in_cset(); 4010 r->set_evacuation_failed(false); 4011 // When moving a young gen region to old gen, we "allocate" that whole region 4012 // there. This is in addition to any already evacuated objects. Notify the 4013 // policy about that. 4014 // Old gen regions do not cause an additional allocation: both the objects 4015 // still in the region and the ones already moved are accounted for elsewhere. 4016 if (r->is_young()) { 4017 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4018 } 4019 // The region is now considered to be old. 4020 r->set_old(); 4021 // Do some allocation statistics accounting. Regions that failed evacuation 4022 // are always made old, so there is no need to update anything in the young 4023 // gen statistics, but we need to update old gen statistics. 4024 size_t used_words = r->marked_bytes() / HeapWordSize; 4025 4026 _failure_used_words += used_words; 4027 _failure_waste_words += HeapRegion::GrainWords - used_words; 4028 4029 g1h->old_set_add(r); 4030 _after_used_bytes += r->used(); 4031 } 4032 return false; 4033 } 4034 4035 void complete_work() { 4036 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4037 4038 _evacuation_info->set_regions_freed(_local_free_list.length()); 4039 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4040 4041 g1h->prepend_to_freelist(&_local_free_list); 4042 g1h->decrement_summary_bytes(_before_used_bytes); 4043 4044 G1Policy* policy = g1h->policy(); 4045 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4046 4047 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4048 } 4049 }; 4050 4051 G1CollectionSet* _collection_set; 4052 G1SerialFreeCollectionSetClosure _cl; 4053 const size_t* _surviving_young_words; 4054 4055 size_t _rs_length; 4056 4057 volatile jint _serial_work_claim; 4058 4059 struct WorkItem { 4060 uint region_idx; 4061 bool is_young; 4062 bool evacuation_failed; 4063 4064 WorkItem(HeapRegion* r) { 4065 region_idx = r->hrm_index(); 4066 is_young = r->is_young(); 4067 evacuation_failed = r->evacuation_failed(); 4068 } 4069 }; 4070 4071 volatile size_t _parallel_work_claim; 4072 size_t _num_work_items; 4073 WorkItem* _work_items; 4074 4075 void do_serial_work() { 4076 // Need to grab the lock to be allowed to modify the old region list. 4077 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4078 _collection_set->iterate(&_cl); 4079 } 4080 4081 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4082 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4083 4084 HeapRegion* r = g1h->region_at(region_idx); 4085 assert(!g1h->is_on_master_free_list(r), "sanity"); 4086 4087 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length); 4088 4089 if (!is_young) { 4090 g1h->_hot_card_cache->reset_card_counts(r); 4091 } 4092 4093 if (!evacuation_failed) { 4094 r->rem_set()->clear_locked(); 4095 } 4096 } 4097 4098 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4099 private: 4100 size_t _cur_idx; 4101 WorkItem* _work_items; 4102 public: 4103 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4104 4105 virtual bool do_heap_region(HeapRegion* r) { 4106 _work_items[_cur_idx++] = WorkItem(r); 4107 return false; 4108 } 4109 }; 4110 4111 void prepare_work() { 4112 G1PrepareFreeCollectionSetClosure cl(_work_items); 4113 _collection_set->iterate(&cl); 4114 } 4115 4116 void complete_work() { 4117 _cl.complete_work(); 4118 4119 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4120 policy->record_max_rs_length(_rs_length); 4121 policy->cset_regions_freed(); 4122 } 4123 public: 4124 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4125 AbstractGangTask("G1 Free Collection Set"), 4126 _collection_set(collection_set), 4127 _cl(evacuation_info, surviving_young_words), 4128 _surviving_young_words(surviving_young_words), 4129 _rs_length(0), 4130 _serial_work_claim(0), 4131 _parallel_work_claim(0), 4132 _num_work_items(collection_set->region_length()), 4133 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4134 prepare_work(); 4135 } 4136 4137 ~G1FreeCollectionSetTask() { 4138 complete_work(); 4139 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4140 } 4141 4142 // Chunk size for work distribution. The chosen value has been determined experimentally 4143 // to be a good tradeoff between overhead and achievable parallelism. 4144 static uint chunk_size() { return 32; } 4145 4146 virtual void work(uint worker_id) { 4147 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4148 4149 // Claim serial work. 4150 if (_serial_work_claim == 0) { 4151 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4152 if (value == 0) { 4153 double serial_time = os::elapsedTime(); 4154 do_serial_work(); 4155 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4156 } 4157 } 4158 4159 // Start parallel work. 4160 double young_time = 0.0; 4161 bool has_young_time = false; 4162 double non_young_time = 0.0; 4163 bool has_non_young_time = false; 4164 4165 while (true) { 4166 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4167 size_t cur = end - chunk_size(); 4168 4169 if (cur >= _num_work_items) { 4170 break; 4171 } 4172 4173 EventGCPhaseParallel event; 4174 double start_time = os::elapsedTime(); 4175 4176 end = MIN2(end, _num_work_items); 4177 4178 for (; cur < end; cur++) { 4179 bool is_young = _work_items[cur].is_young; 4180 4181 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4182 4183 double end_time = os::elapsedTime(); 4184 double time_taken = end_time - start_time; 4185 if (is_young) { 4186 young_time += time_taken; 4187 has_young_time = true; 4188 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4189 } else { 4190 non_young_time += time_taken; 4191 has_non_young_time = true; 4192 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4193 } 4194 start_time = end_time; 4195 } 4196 } 4197 4198 if (has_young_time) { 4199 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4200 } 4201 if (has_non_young_time) { 4202 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4203 } 4204 } 4205 }; 4206 4207 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4208 _eden.clear(); 4209 4210 double free_cset_start_time = os::elapsedTime(); 4211 4212 { 4213 uint const num_regions = _collection_set.region_length(); 4214 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4215 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4216 4217 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4218 4219 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4220 cl.name(), num_workers, num_regions); 4221 workers()->run_task(&cl, num_workers); 4222 } 4223 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4224 4225 collection_set->clear(); 4226 } 4227 4228 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4229 private: 4230 FreeRegionList* _free_region_list; 4231 HeapRegionSet* _proxy_set; 4232 uint _humongous_objects_reclaimed; 4233 uint _humongous_regions_reclaimed; 4234 size_t _freed_bytes; 4235 public: 4236 4237 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4238 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4239 } 4240 4241 virtual bool do_heap_region(HeapRegion* r) { 4242 if (!r->is_starts_humongous()) { 4243 return false; 4244 } 4245 4246 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4247 4248 oop obj = (oop)r->bottom(); 4249 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4250 4251 // The following checks whether the humongous object is live are sufficient. 4252 // The main additional check (in addition to having a reference from the roots 4253 // or the young gen) is whether the humongous object has a remembered set entry. 4254 // 4255 // A humongous object cannot be live if there is no remembered set for it 4256 // because: 4257 // - there can be no references from within humongous starts regions referencing 4258 // the object because we never allocate other objects into them. 4259 // (I.e. there are no intra-region references that may be missed by the 4260 // remembered set) 4261 // - as soon there is a remembered set entry to the humongous starts region 4262 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4263 // until the end of a concurrent mark. 4264 // 4265 // It is not required to check whether the object has been found dead by marking 4266 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4267 // all objects allocated during that time are considered live. 4268 // SATB marking is even more conservative than the remembered set. 4269 // So if at this point in the collection there is no remembered set entry, 4270 // nobody has a reference to it. 4271 // At the start of collection we flush all refinement logs, and remembered sets 4272 // are completely up-to-date wrt to references to the humongous object. 4273 // 4274 // Other implementation considerations: 4275 // - never consider object arrays at this time because they would pose 4276 // considerable effort for cleaning up the the remembered sets. This is 4277 // required because stale remembered sets might reference locations that 4278 // are currently allocated into. 4279 uint region_idx = r->hrm_index(); 4280 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4281 !r->rem_set()->is_empty()) { 4282 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", 4283 region_idx, 4284 (size_t)obj->size() * HeapWordSize, 4285 p2i(r->bottom()), 4286 r->rem_set()->occupied(), 4287 r->rem_set()->strong_code_roots_list_length(), 4288 next_bitmap->is_marked(r->bottom()), 4289 g1h->is_humongous_reclaim_candidate(region_idx), 4290 obj->is_typeArray() 4291 ); 4292 return false; 4293 } 4294 4295 guarantee(obj->is_typeArray(), 4296 "Only eagerly reclaiming type arrays is supported, but the object " 4297 PTR_FORMAT " is not.", p2i(r->bottom())); 4298 4299 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", 4300 region_idx, 4301 (size_t)obj->size() * HeapWordSize, 4302 p2i(r->bottom()), 4303 r->rem_set()->occupied(), 4304 r->rem_set()->strong_code_roots_list_length(), 4305 next_bitmap->is_marked(r->bottom()), 4306 g1h->is_humongous_reclaim_candidate(region_idx), 4307 obj->is_typeArray() 4308 ); 4309 4310 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4311 cm->humongous_object_eagerly_reclaimed(r); 4312 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4313 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4314 region_idx, 4315 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4316 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4317 _humongous_objects_reclaimed++; 4318 do { 4319 HeapRegion* next = g1h->next_region_in_humongous(r); 4320 _freed_bytes += r->used(); 4321 r->set_containing_set(NULL); 4322 _humongous_regions_reclaimed++; 4323 g1h->free_humongous_region(r, _free_region_list); 4324 r = next; 4325 } while (r != NULL); 4326 4327 return false; 4328 } 4329 4330 uint humongous_objects_reclaimed() { 4331 return _humongous_objects_reclaimed; 4332 } 4333 4334 uint humongous_regions_reclaimed() { 4335 return _humongous_regions_reclaimed; 4336 } 4337 4338 size_t bytes_freed() const { 4339 return _freed_bytes; 4340 } 4341 }; 4342 4343 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4344 assert_at_safepoint_on_vm_thread(); 4345 4346 if (!G1EagerReclaimHumongousObjects || 4347 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4348 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4349 return; 4350 } 4351 4352 double start_time = os::elapsedTime(); 4353 4354 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4355 4356 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4357 heap_region_iterate(&cl); 4358 4359 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4360 4361 G1HRPrinter* hrp = hr_printer(); 4362 if (hrp->is_active()) { 4363 FreeRegionListIterator iter(&local_cleanup_list); 4364 while (iter.more_available()) { 4365 HeapRegion* hr = iter.get_next(); 4366 hrp->cleanup(hr); 4367 } 4368 } 4369 4370 prepend_to_freelist(&local_cleanup_list); 4371 decrement_summary_bytes(cl.bytes_freed()); 4372 4373 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4374 cl.humongous_objects_reclaimed()); 4375 } 4376 4377 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4378 public: 4379 virtual bool do_heap_region(HeapRegion* r) { 4380 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4381 G1CollectedHeap::heap()->clear_region_attr(r); 4382 r->clear_young_index_in_cset(); 4383 return false; 4384 } 4385 }; 4386 4387 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4388 G1AbandonCollectionSetClosure cl; 4389 collection_set_iterate_all(&cl); 4390 4391 collection_set->clear(); 4392 collection_set->stop_incremental_building(); 4393 } 4394 4395 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4396 return _allocator->is_retained_old_region(hr); 4397 } 4398 4399 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4400 _eden.add(hr); 4401 _policy->set_region_eden(hr); 4402 } 4403 4404 #ifdef ASSERT 4405 4406 class NoYoungRegionsClosure: public HeapRegionClosure { 4407 private: 4408 bool _success; 4409 public: 4410 NoYoungRegionsClosure() : _success(true) { } 4411 bool do_heap_region(HeapRegion* r) { 4412 if (r->is_young()) { 4413 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4414 p2i(r->bottom()), p2i(r->end())); 4415 _success = false; 4416 } 4417 return false; 4418 } 4419 bool success() { return _success; } 4420 }; 4421 4422 bool G1CollectedHeap::check_young_list_empty() { 4423 bool ret = (young_regions_count() == 0); 4424 4425 NoYoungRegionsClosure closure; 4426 heap_region_iterate(&closure); 4427 ret = ret && closure.success(); 4428 4429 return ret; 4430 } 4431 4432 #endif // ASSERT 4433 4434 class TearDownRegionSetsClosure : public HeapRegionClosure { 4435 HeapRegionSet *_old_set; 4436 4437 public: 4438 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4439 4440 bool do_heap_region(HeapRegion* r) { 4441 if (r->is_old()) { 4442 _old_set->remove(r); 4443 } else if(r->is_young()) { 4444 r->uninstall_surv_rate_group(); 4445 } else { 4446 // We ignore free regions, we'll empty the free list afterwards. 4447 // We ignore humongous and archive regions, we're not tearing down these 4448 // sets. 4449 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4450 "it cannot be another type"); 4451 } 4452 return false; 4453 } 4454 4455 ~TearDownRegionSetsClosure() { 4456 assert(_old_set->is_empty(), "post-condition"); 4457 } 4458 }; 4459 4460 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4461 assert_at_safepoint_on_vm_thread(); 4462 4463 if (!free_list_only) { 4464 TearDownRegionSetsClosure cl(&_old_set); 4465 heap_region_iterate(&cl); 4466 4467 // Note that emptying the _young_list is postponed and instead done as 4468 // the first step when rebuilding the regions sets again. The reason for 4469 // this is that during a full GC string deduplication needs to know if 4470 // a collected region was young or old when the full GC was initiated. 4471 } 4472 _hrm->remove_all_free_regions(); 4473 } 4474 4475 void G1CollectedHeap::increase_used(size_t bytes) { 4476 _summary_bytes_used += bytes; 4477 } 4478 4479 void G1CollectedHeap::decrease_used(size_t bytes) { 4480 assert(_summary_bytes_used >= bytes, 4481 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4482 _summary_bytes_used, bytes); 4483 _summary_bytes_used -= bytes; 4484 } 4485 4486 void G1CollectedHeap::set_used(size_t bytes) { 4487 _summary_bytes_used = bytes; 4488 } 4489 4490 class RebuildRegionSetsClosure : public HeapRegionClosure { 4491 private: 4492 bool _free_list_only; 4493 4494 HeapRegionSet* _old_set; 4495 HeapRegionManager* _hrm; 4496 4497 size_t _total_used; 4498 4499 public: 4500 RebuildRegionSetsClosure(bool free_list_only, 4501 HeapRegionSet* old_set, 4502 HeapRegionManager* hrm) : 4503 _free_list_only(free_list_only), 4504 _old_set(old_set), _hrm(hrm), _total_used(0) { 4505 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4506 if (!free_list_only) { 4507 assert(_old_set->is_empty(), "pre-condition"); 4508 } 4509 } 4510 4511 bool do_heap_region(HeapRegion* r) { 4512 if (r->is_empty()) { 4513 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4514 // Add free regions to the free list 4515 r->set_free(); 4516 _hrm->insert_into_free_list(r); 4517 } else if (!_free_list_only) { 4518 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4519 4520 if (r->is_archive() || r->is_humongous()) { 4521 // We ignore archive and humongous regions. We left these sets unchanged. 4522 } else { 4523 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4524 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4525 r->move_to_old(); 4526 _old_set->add(r); 4527 } 4528 _total_used += r->used(); 4529 } 4530 4531 return false; 4532 } 4533 4534 size_t total_used() { 4535 return _total_used; 4536 } 4537 }; 4538 4539 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4540 assert_at_safepoint_on_vm_thread(); 4541 4542 if (!free_list_only) { 4543 _eden.clear(); 4544 _survivor.clear(); 4545 } 4546 4547 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4548 heap_region_iterate(&cl); 4549 4550 if (!free_list_only) { 4551 set_used(cl.total_used()); 4552 if (_archive_allocator != NULL) { 4553 _archive_allocator->clear_used(); 4554 } 4555 } 4556 assert_used_and_recalculate_used_equal(this); 4557 } 4558 4559 // Methods for the mutator alloc region 4560 4561 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4562 bool force) { 4563 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4564 bool should_allocate = policy()->should_allocate_mutator_region(); 4565 if (force || should_allocate) { 4566 HeapRegion* new_alloc_region = new_region(word_size, 4567 HeapRegionType::Eden, 4568 false /* do_expand */); 4569 if (new_alloc_region != NULL) { 4570 set_region_short_lived_locked(new_alloc_region); 4571 _hr_printer.alloc(new_alloc_region, !should_allocate); 4572 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4573 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4574 return new_alloc_region; 4575 } 4576 } 4577 return NULL; 4578 } 4579 4580 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4581 size_t allocated_bytes) { 4582 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4583 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4584 4585 collection_set()->add_eden_region(alloc_region); 4586 increase_used(allocated_bytes); 4587 _eden.add_used_bytes(allocated_bytes); 4588 _hr_printer.retire(alloc_region); 4589 4590 // We update the eden sizes here, when the region is retired, 4591 // instead of when it's allocated, since this is the point that its 4592 // used space has been recorded in _summary_bytes_used. 4593 g1mm()->update_eden_size(); 4594 } 4595 4596 // Methods for the GC alloc regions 4597 4598 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4599 if (dest.is_old()) { 4600 return true; 4601 } else { 4602 return survivor_regions_count() < policy()->max_survivor_regions(); 4603 } 4604 } 4605 4606 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) { 4607 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4608 4609 if (!has_more_regions(dest)) { 4610 return NULL; 4611 } 4612 4613 HeapRegionType type; 4614 if (dest.is_young()) { 4615 type = HeapRegionType::Survivor; 4616 } else { 4617 type = HeapRegionType::Old; 4618 } 4619 4620 HeapRegion* new_alloc_region = new_region(word_size, 4621 type, 4622 true /* do_expand */); 4623 4624 if (new_alloc_region != NULL) { 4625 if (type.is_survivor()) { 4626 new_alloc_region->set_survivor(); 4627 _survivor.add(new_alloc_region); 4628 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4629 } else { 4630 new_alloc_region->set_old(); 4631 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4632 } 4633 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4634 register_region_with_region_attr(new_alloc_region); 4635 _hr_printer.alloc(new_alloc_region); 4636 return new_alloc_region; 4637 } 4638 return NULL; 4639 } 4640 4641 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4642 size_t allocated_bytes, 4643 G1HeapRegionAttr dest) { 4644 policy()->record_bytes_copied_during_gc(allocated_bytes); 4645 if (dest.is_old()) { 4646 old_set_add(alloc_region); 4647 } else { 4648 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4649 _survivor.add_used_bytes(allocated_bytes); 4650 } 4651 4652 bool const during_im = collector_state()->in_initial_mark_gc(); 4653 if (during_im && allocated_bytes > 0) { 4654 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4655 } 4656 _hr_printer.retire(alloc_region); 4657 } 4658 4659 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4660 bool expanded = false; 4661 uint index = _hrm->find_highest_free(&expanded); 4662 4663 if (index != G1_NO_HRM_INDEX) { 4664 if (expanded) { 4665 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4666 HeapRegion::GrainWords * HeapWordSize); 4667 } 4668 _hrm->allocate_free_regions_starting_at(index, 1); 4669 return region_at(index); 4670 } 4671 return NULL; 4672 } 4673 4674 // Optimized nmethod scanning 4675 4676 class RegisterNMethodOopClosure: public OopClosure { 4677 G1CollectedHeap* _g1h; 4678 nmethod* _nm; 4679 4680 template <class T> void do_oop_work(T* p) { 4681 T heap_oop = RawAccess<>::oop_load(p); 4682 if (!CompressedOops::is_null(heap_oop)) { 4683 oop obj = CompressedOops::decode_not_null(heap_oop); 4684 HeapRegion* hr = _g1h->heap_region_containing(obj); 4685 assert(!hr->is_continues_humongous(), 4686 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4687 " starting at " HR_FORMAT, 4688 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4689 4690 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4691 hr->add_strong_code_root_locked(_nm); 4692 } 4693 } 4694 4695 public: 4696 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4697 _g1h(g1h), _nm(nm) {} 4698 4699 void do_oop(oop* p) { do_oop_work(p); } 4700 void do_oop(narrowOop* p) { do_oop_work(p); } 4701 }; 4702 4703 class UnregisterNMethodOopClosure: public OopClosure { 4704 G1CollectedHeap* _g1h; 4705 nmethod* _nm; 4706 4707 template <class T> void do_oop_work(T* p) { 4708 T heap_oop = RawAccess<>::oop_load(p); 4709 if (!CompressedOops::is_null(heap_oop)) { 4710 oop obj = CompressedOops::decode_not_null(heap_oop); 4711 HeapRegion* hr = _g1h->heap_region_containing(obj); 4712 assert(!hr->is_continues_humongous(), 4713 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4714 " starting at " HR_FORMAT, 4715 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4716 4717 hr->remove_strong_code_root(_nm); 4718 } 4719 } 4720 4721 public: 4722 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4723 _g1h(g1h), _nm(nm) {} 4724 4725 void do_oop(oop* p) { do_oop_work(p); } 4726 void do_oop(narrowOop* p) { do_oop_work(p); } 4727 }; 4728 4729 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4730 guarantee(nm != NULL, "sanity"); 4731 RegisterNMethodOopClosure reg_cl(this, nm); 4732 nm->oops_do(®_cl); 4733 } 4734 4735 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4736 guarantee(nm != NULL, "sanity"); 4737 UnregisterNMethodOopClosure reg_cl(this, nm); 4738 nm->oops_do(®_cl, true); 4739 } 4740 4741 void G1CollectedHeap::purge_code_root_memory() { 4742 double purge_start = os::elapsedTime(); 4743 G1CodeRootSet::purge(); 4744 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4745 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4746 } 4747 4748 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4749 G1CollectedHeap* _g1h; 4750 4751 public: 4752 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4753 _g1h(g1h) {} 4754 4755 void do_code_blob(CodeBlob* cb) { 4756 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4757 if (nm == NULL) { 4758 return; 4759 } 4760 4761 _g1h->register_nmethod(nm); 4762 } 4763 }; 4764 4765 void G1CollectedHeap::rebuild_strong_code_roots() { 4766 RebuildStrongCodeRootClosure blob_cl(this); 4767 CodeCache::blobs_do(&blob_cl); 4768 } 4769 4770 void G1CollectedHeap::initialize_serviceability() { 4771 _g1mm->initialize_serviceability(); 4772 } 4773 4774 MemoryUsage G1CollectedHeap::memory_usage() { 4775 return _g1mm->memory_usage(); 4776 } 4777 4778 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4779 return _g1mm->memory_managers(); 4780 } 4781 4782 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4783 return _g1mm->memory_pools(); 4784 }