1 /* 2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/g1Allocator.inline.hpp" 32 #include "gc/g1/g1Arguments.hpp" 33 #include "gc/g1/g1BarrierSet.hpp" 34 #include "gc/g1/g1CardTableEntryClosure.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectionSet.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 41 #include "gc/g1/g1DirtyCardQueue.hpp" 42 #include "gc/g1/g1EvacStats.inline.hpp" 43 #include "gc/g1/g1FullCollector.hpp" 44 #include "gc/g1/g1GCPhaseTimes.hpp" 45 #include "gc/g1/g1HeapSizingPolicy.hpp" 46 #include "gc/g1/g1HeapTransition.hpp" 47 #include "gc/g1/g1HeapVerifier.hpp" 48 #include "gc/g1/g1HotCardCache.hpp" 49 #include "gc/g1/g1MemoryPool.hpp" 50 #include "gc/g1/g1OopClosures.inline.hpp" 51 #include "gc/g1/g1ParallelCleaning.hpp" 52 #include "gc/g1/g1ParScanThreadState.inline.hpp" 53 #include "gc/g1/g1Policy.hpp" 54 #include "gc/g1/g1RedirtyCardsQueue.hpp" 55 #include "gc/g1/g1RegionToSpaceMapper.hpp" 56 #include "gc/g1/g1RemSet.hpp" 57 #include "gc/g1/g1RootClosures.hpp" 58 #include "gc/g1/g1RootProcessor.hpp" 59 #include "gc/g1/g1SATBMarkQueueSet.hpp" 60 #include "gc/g1/g1StringDedup.hpp" 61 #include "gc/g1/g1ThreadLocalData.hpp" 62 #include "gc/g1/g1Trace.hpp" 63 #include "gc/g1/g1YCTypes.hpp" 64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 65 #include "gc/g1/g1VMOperations.hpp" 66 #include "gc/g1/heapRegion.inline.hpp" 67 #include "gc/g1/heapRegionRemSet.hpp" 68 #include "gc/g1/heapRegionSet.inline.hpp" 69 #include "gc/shared/gcBehaviours.hpp" 70 #include "gc/shared/gcHeapSummary.hpp" 71 #include "gc/shared/gcId.hpp" 72 #include "gc/shared/gcLocker.hpp" 73 #include "gc/shared/gcTimer.hpp" 74 #include "gc/shared/gcTraceTime.inline.hpp" 75 #include "gc/shared/generationSpec.hpp" 76 #include "gc/shared/isGCActiveMark.hpp" 77 #include "gc/shared/locationPrinter.inline.hpp" 78 #include "gc/shared/oopStorageParState.hpp" 79 #include "gc/shared/preservedMarks.inline.hpp" 80 #include "gc/shared/suspendibleThreadSet.hpp" 81 #include "gc/shared/referenceProcessor.inline.hpp" 82 #include "gc/shared/taskqueue.inline.hpp" 83 #include "gc/shared/weakProcessor.inline.hpp" 84 #include "gc/shared/workerPolicy.hpp" 85 #include "logging/log.hpp" 86 #include "memory/allocation.hpp" 87 #include "memory/iterator.hpp" 88 #include "memory/resourceArea.hpp" 89 #include "memory/universe.hpp" 90 #include "oops/access.inline.hpp" 91 #include "oops/compressedOops.inline.hpp" 92 #include "oops/oop.inline.hpp" 93 #include "runtime/atomic.hpp" 94 #include "runtime/flags/flagSetting.hpp" 95 #include "runtime/handles.inline.hpp" 96 #include "runtime/init.hpp" 97 #include "runtime/orderAccess.hpp" 98 #include "runtime/threadSMR.hpp" 99 #include "runtime/vmThread.hpp" 100 #include "utilities/align.hpp" 101 #include "utilities/globalDefinitions.hpp" 102 #include "utilities/stack.inline.hpp" 103 104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 105 106 // INVARIANTS/NOTES 107 // 108 // All allocation activity covered by the G1CollectedHeap interface is 109 // serialized by acquiring the HeapLock. This happens in mem_allocate 110 // and allocate_new_tlab, which are the "entry" points to the 111 // allocation code from the rest of the JVM. (Note that this does not 112 // apply to TLAB allocation, which is not part of this interface: it 113 // is done by clients of this interface.) 114 115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 116 private: 117 size_t _num_dirtied; 118 G1CollectedHeap* _g1h; 119 G1CardTable* _g1_ct; 120 121 HeapRegion* region_for_card(CardValue* card_ptr) const { 122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 123 } 124 125 bool will_become_free(HeapRegion* hr) const { 126 // A region will be freed by free_collection_set if the region is in the 127 // collection set and has not had an evacuation failure. 128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 129 } 130 131 public: 132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 134 135 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 136 HeapRegion* hr = region_for_card(card_ptr); 137 138 // Should only dirty cards in regions that won't be freed. 139 if (!will_become_free(hr)) { 140 *card_ptr = G1CardTable::dirty_card_val(); 141 _num_dirtied++; 142 } 143 } 144 145 size_t num_dirtied() const { return _num_dirtied; } 146 }; 147 148 149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 151 } 152 153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 154 // The from card cache is not the memory that is actually committed. So we cannot 155 // take advantage of the zero_filled parameter. 156 reset_from_card_cache(start_idx, num_regions); 157 } 158 159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 160 Ticks start = Ticks::now(); 161 workers()->run_task(task, workers()->active_workers()); 162 return Ticks::now() - start; 163 } 164 165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 166 MemRegion mr) { 167 return new HeapRegion(hrs_index, bot(), mr); 168 } 169 170 // Private methods. 171 172 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) { 173 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 174 "the only time we use this to allocate a humongous region is " 175 "when we are allocating a single humongous region"); 176 177 HeapRegion* res = _hrm->allocate_free_region(type); 178 179 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 180 // Currently, only attempts to allocate GC alloc regions set 181 // do_expand to true. So, we should only reach here during a 182 // safepoint. If this assumption changes we might have to 183 // reconsider the use of _expand_heap_after_alloc_failure. 184 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 185 186 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 187 word_size * HeapWordSize); 188 189 if (expand(word_size * HeapWordSize)) { 190 // Given that expand() succeeded in expanding the heap, and we 191 // always expand the heap by an amount aligned to the heap 192 // region size, the free list should in theory not be empty. 193 // In either case allocate_free_region() will check for NULL. 194 res = _hrm->allocate_free_region(type); 195 } else { 196 _expand_heap_after_alloc_failure = false; 197 } 198 } 199 return res; 200 } 201 202 HeapWord* 203 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 204 uint num_regions, 205 size_t word_size) { 206 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 207 assert(is_humongous(word_size), "word_size should be humongous"); 208 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 209 210 // Index of last region in the series. 211 uint last = first + num_regions - 1; 212 213 // We need to initialize the region(s) we just discovered. This is 214 // a bit tricky given that it can happen concurrently with 215 // refinement threads refining cards on these regions and 216 // potentially wanting to refine the BOT as they are scanning 217 // those cards (this can happen shortly after a cleanup; see CR 218 // 6991377). So we have to set up the region(s) carefully and in 219 // a specific order. 220 221 // The word size sum of all the regions we will allocate. 222 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 223 assert(word_size <= word_size_sum, "sanity"); 224 225 // This will be the "starts humongous" region. 226 HeapRegion* first_hr = region_at(first); 227 // The header of the new object will be placed at the bottom of 228 // the first region. 229 HeapWord* new_obj = first_hr->bottom(); 230 // This will be the new top of the new object. 231 HeapWord* obj_top = new_obj + word_size; 232 233 // First, we need to zero the header of the space that we will be 234 // allocating. When we update top further down, some refinement 235 // threads might try to scan the region. By zeroing the header we 236 // ensure that any thread that will try to scan the region will 237 // come across the zero klass word and bail out. 238 // 239 // NOTE: It would not have been correct to have used 240 // CollectedHeap::fill_with_object() and make the space look like 241 // an int array. The thread that is doing the allocation will 242 // later update the object header to a potentially different array 243 // type and, for a very short period of time, the klass and length 244 // fields will be inconsistent. This could cause a refinement 245 // thread to calculate the object size incorrectly. 246 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 247 248 // Next, pad out the unused tail of the last region with filler 249 // objects, for improved usage accounting. 250 // How many words we use for filler objects. 251 size_t word_fill_size = word_size_sum - word_size; 252 253 // How many words memory we "waste" which cannot hold a filler object. 254 size_t words_not_fillable = 0; 255 256 if (word_fill_size >= min_fill_size()) { 257 fill_with_objects(obj_top, word_fill_size); 258 } else if (word_fill_size > 0) { 259 // We have space to fill, but we cannot fit an object there. 260 words_not_fillable = word_fill_size; 261 word_fill_size = 0; 262 } 263 264 // We will set up the first region as "starts humongous". This 265 // will also update the BOT covering all the regions to reflect 266 // that there is a single object that starts at the bottom of the 267 // first region. 268 first_hr->set_starts_humongous(obj_top, word_fill_size); 269 _policy->remset_tracker()->update_at_allocate(first_hr); 270 // Then, if there are any, we will set up the "continues 271 // humongous" regions. 272 HeapRegion* hr = NULL; 273 for (uint i = first + 1; i <= last; ++i) { 274 hr = region_at(i); 275 hr->set_continues_humongous(first_hr); 276 _policy->remset_tracker()->update_at_allocate(hr); 277 } 278 279 // Up to this point no concurrent thread would have been able to 280 // do any scanning on any region in this series. All the top 281 // fields still point to bottom, so the intersection between 282 // [bottom,top] and [card_start,card_end] will be empty. Before we 283 // update the top fields, we'll do a storestore to make sure that 284 // no thread sees the update to top before the zeroing of the 285 // object header and the BOT initialization. 286 OrderAccess::storestore(); 287 288 // Now, we will update the top fields of the "continues humongous" 289 // regions except the last one. 290 for (uint i = first; i < last; ++i) { 291 hr = region_at(i); 292 hr->set_top(hr->end()); 293 } 294 295 hr = region_at(last); 296 // If we cannot fit a filler object, we must set top to the end 297 // of the humongous object, otherwise we cannot iterate the heap 298 // and the BOT will not be complete. 299 hr->set_top(hr->end() - words_not_fillable); 300 301 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 302 "obj_top should be in last region"); 303 304 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 305 306 assert(words_not_fillable == 0 || 307 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 308 "Miscalculation in humongous allocation"); 309 310 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 311 312 for (uint i = first; i <= last; ++i) { 313 hr = region_at(i); 314 _humongous_set.add(hr); 315 _hr_printer.alloc(hr); 316 } 317 318 return new_obj; 319 } 320 321 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 322 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 323 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 324 } 325 326 // If could fit into free regions w/o expansion, try. 327 // Otherwise, if can expand, do so. 328 // Otherwise, if using ex regions might help, try with ex given back. 329 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 330 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 331 332 _verifier->verify_region_sets_optional(); 333 334 uint first = G1_NO_HRM_INDEX; 335 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 336 337 if (obj_regions == 1) { 338 // Only one region to allocate, try to use a fast path by directly allocating 339 // from the free lists. Do not try to expand here, we will potentially do that 340 // later. 341 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 342 if (hr != NULL) { 343 first = hr->hrm_index(); 344 } 345 } else { 346 // Policy: Try only empty regions (i.e. already committed first). Maybe we 347 // are lucky enough to find some. 348 first = _hrm->find_contiguous_only_empty(obj_regions); 349 if (first != G1_NO_HRM_INDEX) { 350 _hrm->allocate_free_regions_starting_at(first, obj_regions); 351 } 352 } 353 354 if (first == G1_NO_HRM_INDEX) { 355 // Policy: We could not find enough regions for the humongous object in the 356 // free list. Look through the heap to find a mix of free and uncommitted regions. 357 // If so, try expansion. 358 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 359 if (first != G1_NO_HRM_INDEX) { 360 // We found something. Make sure these regions are committed, i.e. expand 361 // the heap. Alternatively we could do a defragmentation GC. 362 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 363 word_size * HeapWordSize); 364 365 _hrm->expand_at(first, obj_regions, workers()); 366 policy()->record_new_heap_size(num_regions()); 367 368 #ifdef ASSERT 369 for (uint i = first; i < first + obj_regions; ++i) { 370 HeapRegion* hr = region_at(i); 371 assert(hr->is_free(), "sanity"); 372 assert(hr->is_empty(), "sanity"); 373 assert(is_on_master_free_list(hr), "sanity"); 374 } 375 #endif 376 _hrm->allocate_free_regions_starting_at(first, obj_regions); 377 } else { 378 // Policy: Potentially trigger a defragmentation GC. 379 } 380 } 381 382 HeapWord* result = NULL; 383 if (first != G1_NO_HRM_INDEX) { 384 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 385 assert(result != NULL, "it should always return a valid result"); 386 387 // A successful humongous object allocation changes the used space 388 // information of the old generation so we need to recalculate the 389 // sizes and update the jstat counters here. 390 g1mm()->update_sizes(); 391 } 392 393 _verifier->verify_region_sets_optional(); 394 395 return result; 396 } 397 398 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 399 size_t requested_size, 400 size_t* actual_size) { 401 assert_heap_not_locked_and_not_at_safepoint(); 402 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 403 404 return attempt_allocation(min_size, requested_size, actual_size); 405 } 406 407 HeapWord* 408 G1CollectedHeap::mem_allocate(size_t word_size, 409 bool* gc_overhead_limit_was_exceeded) { 410 assert_heap_not_locked_and_not_at_safepoint(); 411 412 if (is_humongous(word_size)) { 413 return attempt_allocation_humongous(word_size); 414 } 415 size_t dummy = 0; 416 return attempt_allocation(word_size, word_size, &dummy); 417 } 418 419 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 420 ResourceMark rm; // For retrieving the thread names in log messages. 421 422 // Make sure you read the note in attempt_allocation_humongous(). 423 424 assert_heap_not_locked_and_not_at_safepoint(); 425 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 426 "be called for humongous allocation requests"); 427 428 // We should only get here after the first-level allocation attempt 429 // (attempt_allocation()) failed to allocate. 430 431 // We will loop until a) we manage to successfully perform the 432 // allocation or b) we successfully schedule a collection which 433 // fails to perform the allocation. b) is the only case when we'll 434 // return NULL. 435 HeapWord* result = NULL; 436 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 437 bool should_try_gc; 438 uint gc_count_before; 439 440 { 441 MutexLocker x(Heap_lock); 442 result = _allocator->attempt_allocation_locked(word_size); 443 if (result != NULL) { 444 return result; 445 } 446 447 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 448 // This is different to when only GCLocker::needs_gc() is set: try to avoid 449 // waiting because the GCLocker is active to not wait too long. 450 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 451 // No need for an ergo message here, can_expand_young_list() does this when 452 // it returns true. 453 result = _allocator->attempt_allocation_force(word_size); 454 if (result != NULL) { 455 return result; 456 } 457 } 458 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 459 // the GCLocker initiated GC has been performed and then retry. This includes 460 // the case when the GC Locker is not active but has not been performed. 461 should_try_gc = !GCLocker::needs_gc(); 462 // Read the GC count while still holding the Heap_lock. 463 gc_count_before = total_collections(); 464 } 465 466 if (should_try_gc) { 467 bool succeeded; 468 result = do_collection_pause(word_size, gc_count_before, &succeeded, 469 GCCause::_g1_inc_collection_pause); 470 if (result != NULL) { 471 assert(succeeded, "only way to get back a non-NULL result"); 472 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 473 Thread::current()->name(), p2i(result)); 474 return result; 475 } 476 477 if (succeeded) { 478 // We successfully scheduled a collection which failed to allocate. No 479 // point in trying to allocate further. We'll just return NULL. 480 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 481 SIZE_FORMAT " words", Thread::current()->name(), word_size); 482 return NULL; 483 } 484 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 485 Thread::current()->name(), word_size); 486 } else { 487 // Failed to schedule a collection. 488 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 489 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 490 SIZE_FORMAT " words", Thread::current()->name(), word_size); 491 return NULL; 492 } 493 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 494 // The GCLocker is either active or the GCLocker initiated 495 // GC has not yet been performed. Stall until it is and 496 // then retry the allocation. 497 GCLocker::stall_until_clear(); 498 gclocker_retry_count += 1; 499 } 500 501 // We can reach here if we were unsuccessful in scheduling a 502 // collection (because another thread beat us to it) or if we were 503 // stalled due to the GC locker. In either can we should retry the 504 // allocation attempt in case another thread successfully 505 // performed a collection and reclaimed enough space. We do the 506 // first attempt (without holding the Heap_lock) here and the 507 // follow-on attempt will be at the start of the next loop 508 // iteration (after taking the Heap_lock). 509 size_t dummy = 0; 510 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 511 if (result != NULL) { 512 return result; 513 } 514 515 // Give a warning if we seem to be looping forever. 516 if ((QueuedAllocationWarningCount > 0) && 517 (try_count % QueuedAllocationWarningCount == 0)) { 518 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 519 Thread::current()->name(), try_count, word_size); 520 } 521 } 522 523 ShouldNotReachHere(); 524 return NULL; 525 } 526 527 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 528 assert_at_safepoint_on_vm_thread(); 529 if (_archive_allocator == NULL) { 530 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 531 } 532 } 533 534 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 535 // Allocations in archive regions cannot be of a size that would be considered 536 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 537 // may be different at archive-restore time. 538 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 539 } 540 541 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 542 assert_at_safepoint_on_vm_thread(); 543 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 544 if (is_archive_alloc_too_large(word_size)) { 545 return NULL; 546 } 547 return _archive_allocator->archive_mem_allocate(word_size); 548 } 549 550 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 551 size_t end_alignment_in_bytes) { 552 assert_at_safepoint_on_vm_thread(); 553 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 554 555 // Call complete_archive to do the real work, filling in the MemRegion 556 // array with the archive regions. 557 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 558 delete _archive_allocator; 559 _archive_allocator = NULL; 560 } 561 562 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 563 assert(ranges != NULL, "MemRegion array NULL"); 564 assert(count != 0, "No MemRegions provided"); 565 MemRegion reserved = _hrm->reserved(); 566 for (size_t i = 0; i < count; i++) { 567 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 568 return false; 569 } 570 } 571 return true; 572 } 573 574 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 575 size_t count, 576 bool open) { 577 assert(!is_init_completed(), "Expect to be called at JVM init time"); 578 assert(ranges != NULL, "MemRegion array NULL"); 579 assert(count != 0, "No MemRegions provided"); 580 MutexLocker x(Heap_lock); 581 582 MemRegion reserved = _hrm->reserved(); 583 HeapWord* prev_last_addr = NULL; 584 HeapRegion* prev_last_region = NULL; 585 586 // Temporarily disable pretouching of heap pages. This interface is used 587 // when mmap'ing archived heap data in, so pre-touching is wasted. 588 FlagSetting fs(AlwaysPreTouch, false); 589 590 // Enable archive object checking used by G1MarkSweep. We have to let it know 591 // about each archive range, so that objects in those ranges aren't marked. 592 G1ArchiveAllocator::enable_archive_object_check(); 593 594 // For each specified MemRegion range, allocate the corresponding G1 595 // regions and mark them as archive regions. We expect the ranges 596 // in ascending starting address order, without overlap. 597 for (size_t i = 0; i < count; i++) { 598 MemRegion curr_range = ranges[i]; 599 HeapWord* start_address = curr_range.start(); 600 size_t word_size = curr_range.word_size(); 601 HeapWord* last_address = curr_range.last(); 602 size_t commits = 0; 603 604 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 605 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 606 p2i(start_address), p2i(last_address)); 607 guarantee(start_address > prev_last_addr, 608 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 609 p2i(start_address), p2i(prev_last_addr)); 610 prev_last_addr = last_address; 611 612 // Check for ranges that start in the same G1 region in which the previous 613 // range ended, and adjust the start address so we don't try to allocate 614 // the same region again. If the current range is entirely within that 615 // region, skip it, just adjusting the recorded top. 616 HeapRegion* start_region = _hrm->addr_to_region(start_address); 617 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 618 start_address = start_region->end(); 619 if (start_address > last_address) { 620 increase_used(word_size * HeapWordSize); 621 start_region->set_top(last_address + 1); 622 continue; 623 } 624 start_region->set_top(start_address); 625 curr_range = MemRegion(start_address, last_address + 1); 626 start_region = _hrm->addr_to_region(start_address); 627 } 628 629 // Perform the actual region allocation, exiting if it fails. 630 // Then note how much new space we have allocated. 631 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 632 return false; 633 } 634 increase_used(word_size * HeapWordSize); 635 if (commits != 0) { 636 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 637 HeapRegion::GrainWords * HeapWordSize * commits); 638 639 } 640 641 // Mark each G1 region touched by the range as archive, add it to 642 // the old set, and set top. 643 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 644 HeapRegion* last_region = _hrm->addr_to_region(last_address); 645 prev_last_region = last_region; 646 647 while (curr_region != NULL) { 648 assert(curr_region->is_empty() && !curr_region->is_pinned(), 649 "Region already in use (index %u)", curr_region->hrm_index()); 650 if (open) { 651 curr_region->set_open_archive(); 652 } else { 653 curr_region->set_closed_archive(); 654 } 655 _hr_printer.alloc(curr_region); 656 _archive_set.add(curr_region); 657 HeapWord* top; 658 HeapRegion* next_region; 659 if (curr_region != last_region) { 660 top = curr_region->end(); 661 next_region = _hrm->next_region_in_heap(curr_region); 662 } else { 663 top = last_address + 1; 664 next_region = NULL; 665 } 666 curr_region->set_top(top); 667 curr_region->set_first_dead(top); 668 curr_region->set_end_of_live(top); 669 curr_region = next_region; 670 } 671 672 // Notify mark-sweep of the archive 673 G1ArchiveAllocator::set_range_archive(curr_range, open); 674 } 675 return true; 676 } 677 678 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 679 assert(!is_init_completed(), "Expect to be called at JVM init time"); 680 assert(ranges != NULL, "MemRegion array NULL"); 681 assert(count != 0, "No MemRegions provided"); 682 MemRegion reserved = _hrm->reserved(); 683 HeapWord *prev_last_addr = NULL; 684 HeapRegion* prev_last_region = NULL; 685 686 // For each MemRegion, create filler objects, if needed, in the G1 regions 687 // that contain the address range. The address range actually within the 688 // MemRegion will not be modified. That is assumed to have been initialized 689 // elsewhere, probably via an mmap of archived heap data. 690 MutexLocker x(Heap_lock); 691 for (size_t i = 0; i < count; i++) { 692 HeapWord* start_address = ranges[i].start(); 693 HeapWord* last_address = ranges[i].last(); 694 695 assert(reserved.contains(start_address) && reserved.contains(last_address), 696 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 697 p2i(start_address), p2i(last_address)); 698 assert(start_address > prev_last_addr, 699 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 700 p2i(start_address), p2i(prev_last_addr)); 701 702 HeapRegion* start_region = _hrm->addr_to_region(start_address); 703 HeapRegion* last_region = _hrm->addr_to_region(last_address); 704 HeapWord* bottom_address = start_region->bottom(); 705 706 // Check for a range beginning in the same region in which the 707 // previous one ended. 708 if (start_region == prev_last_region) { 709 bottom_address = prev_last_addr + 1; 710 } 711 712 // Verify that the regions were all marked as archive regions by 713 // alloc_archive_regions. 714 HeapRegion* curr_region = start_region; 715 while (curr_region != NULL) { 716 guarantee(curr_region->is_archive(), 717 "Expected archive region at index %u", curr_region->hrm_index()); 718 if (curr_region != last_region) { 719 curr_region = _hrm->next_region_in_heap(curr_region); 720 } else { 721 curr_region = NULL; 722 } 723 } 724 725 prev_last_addr = last_address; 726 prev_last_region = last_region; 727 728 // Fill the memory below the allocated range with dummy object(s), 729 // if the region bottom does not match the range start, or if the previous 730 // range ended within the same G1 region, and there is a gap. 731 if (start_address != bottom_address) { 732 size_t fill_size = pointer_delta(start_address, bottom_address); 733 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 734 increase_used(fill_size * HeapWordSize); 735 } 736 } 737 } 738 739 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 740 size_t desired_word_size, 741 size_t* actual_word_size) { 742 assert_heap_not_locked_and_not_at_safepoint(); 743 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 744 "be called for humongous allocation requests"); 745 746 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 747 748 if (result == NULL) { 749 *actual_word_size = desired_word_size; 750 result = attempt_allocation_slow(desired_word_size); 751 } 752 753 assert_heap_not_locked(); 754 if (result != NULL) { 755 assert(*actual_word_size != 0, "Actual size must have been set here"); 756 dirty_young_block(result, *actual_word_size); 757 } else { 758 *actual_word_size = 0; 759 } 760 761 return result; 762 } 763 764 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 765 assert(!is_init_completed(), "Expect to be called at JVM init time"); 766 assert(ranges != NULL, "MemRegion array NULL"); 767 assert(count != 0, "No MemRegions provided"); 768 MemRegion reserved = _hrm->reserved(); 769 HeapWord* prev_last_addr = NULL; 770 HeapRegion* prev_last_region = NULL; 771 size_t size_used = 0; 772 size_t uncommitted_regions = 0; 773 774 // For each Memregion, free the G1 regions that constitute it, and 775 // notify mark-sweep that the range is no longer to be considered 'archive.' 776 MutexLocker x(Heap_lock); 777 for (size_t i = 0; i < count; i++) { 778 HeapWord* start_address = ranges[i].start(); 779 HeapWord* last_address = ranges[i].last(); 780 781 assert(reserved.contains(start_address) && reserved.contains(last_address), 782 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 783 p2i(start_address), p2i(last_address)); 784 assert(start_address > prev_last_addr, 785 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 786 p2i(start_address), p2i(prev_last_addr)); 787 size_used += ranges[i].byte_size(); 788 prev_last_addr = last_address; 789 790 HeapRegion* start_region = _hrm->addr_to_region(start_address); 791 HeapRegion* last_region = _hrm->addr_to_region(last_address); 792 793 // Check for ranges that start in the same G1 region in which the previous 794 // range ended, and adjust the start address so we don't try to free 795 // the same region again. If the current range is entirely within that 796 // region, skip it. 797 if (start_region == prev_last_region) { 798 start_address = start_region->end(); 799 if (start_address > last_address) { 800 continue; 801 } 802 start_region = _hrm->addr_to_region(start_address); 803 } 804 prev_last_region = last_region; 805 806 // After verifying that each region was marked as an archive region by 807 // alloc_archive_regions, set it free and empty and uncommit it. 808 HeapRegion* curr_region = start_region; 809 while (curr_region != NULL) { 810 guarantee(curr_region->is_archive(), 811 "Expected archive region at index %u", curr_region->hrm_index()); 812 uint curr_index = curr_region->hrm_index(); 813 _archive_set.remove(curr_region); 814 curr_region->set_free(); 815 curr_region->set_top(curr_region->bottom()); 816 if (curr_region != last_region) { 817 curr_region = _hrm->next_region_in_heap(curr_region); 818 } else { 819 curr_region = NULL; 820 } 821 _hrm->shrink_at(curr_index, 1); 822 uncommitted_regions++; 823 } 824 825 // Notify mark-sweep that this is no longer an archive range. 826 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 827 } 828 829 if (uncommitted_regions != 0) { 830 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 831 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 832 } 833 decrease_used(size_used); 834 } 835 836 oop G1CollectedHeap::materialize_archived_object(oop obj) { 837 assert(obj != NULL, "archived obj is NULL"); 838 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 839 840 // Loading an archived object makes it strongly reachable. If it is 841 // loaded during concurrent marking, it must be enqueued to the SATB 842 // queue, shading the previously white object gray. 843 G1BarrierSet::enqueue(obj); 844 845 return obj; 846 } 847 848 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 849 ResourceMark rm; // For retrieving the thread names in log messages. 850 851 // The structure of this method has a lot of similarities to 852 // attempt_allocation_slow(). The reason these two were not merged 853 // into a single one is that such a method would require several "if 854 // allocation is not humongous do this, otherwise do that" 855 // conditional paths which would obscure its flow. In fact, an early 856 // version of this code did use a unified method which was harder to 857 // follow and, as a result, it had subtle bugs that were hard to 858 // track down. So keeping these two methods separate allows each to 859 // be more readable. It will be good to keep these two in sync as 860 // much as possible. 861 862 assert_heap_not_locked_and_not_at_safepoint(); 863 assert(is_humongous(word_size), "attempt_allocation_humongous() " 864 "should only be called for humongous allocations"); 865 866 // Humongous objects can exhaust the heap quickly, so we should check if we 867 // need to start a marking cycle at each humongous object allocation. We do 868 // the check before we do the actual allocation. The reason for doing it 869 // before the allocation is that we avoid having to keep track of the newly 870 // allocated memory while we do a GC. 871 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 872 word_size)) { 873 collect(GCCause::_g1_humongous_allocation); 874 } 875 876 // We will loop until a) we manage to successfully perform the 877 // allocation or b) we successfully schedule a collection which 878 // fails to perform the allocation. b) is the only case when we'll 879 // return NULL. 880 HeapWord* result = NULL; 881 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 882 bool should_try_gc; 883 uint gc_count_before; 884 885 886 { 887 MutexLocker x(Heap_lock); 888 889 // Given that humongous objects are not allocated in young 890 // regions, we'll first try to do the allocation without doing a 891 // collection hoping that there's enough space in the heap. 892 result = humongous_obj_allocate(word_size); 893 if (result != NULL) { 894 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 895 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 896 return result; 897 } 898 899 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 900 // the GCLocker initiated GC has been performed and then retry. This includes 901 // the case when the GC Locker is not active but has not been performed. 902 should_try_gc = !GCLocker::needs_gc(); 903 // Read the GC count while still holding the Heap_lock. 904 gc_count_before = total_collections(); 905 } 906 907 if (should_try_gc) { 908 bool succeeded; 909 result = do_collection_pause(word_size, gc_count_before, &succeeded, 910 GCCause::_g1_humongous_allocation); 911 if (result != NULL) { 912 assert(succeeded, "only way to get back a non-NULL result"); 913 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 914 Thread::current()->name(), p2i(result)); 915 return result; 916 } 917 918 if (succeeded) { 919 // We successfully scheduled a collection which failed to allocate. No 920 // point in trying to allocate further. We'll just return NULL. 921 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 922 SIZE_FORMAT " words", Thread::current()->name(), word_size); 923 return NULL; 924 } 925 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 926 Thread::current()->name(), word_size); 927 } else { 928 // Failed to schedule a collection. 929 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 930 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 931 SIZE_FORMAT " words", Thread::current()->name(), word_size); 932 return NULL; 933 } 934 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 935 // The GCLocker is either active or the GCLocker initiated 936 // GC has not yet been performed. Stall until it is and 937 // then retry the allocation. 938 GCLocker::stall_until_clear(); 939 gclocker_retry_count += 1; 940 } 941 942 943 // We can reach here if we were unsuccessful in scheduling a 944 // collection (because another thread beat us to it) or if we were 945 // stalled due to the GC locker. In either can we should retry the 946 // allocation attempt in case another thread successfully 947 // performed a collection and reclaimed enough space. 948 // Humongous object allocation always needs a lock, so we wait for the retry 949 // in the next iteration of the loop, unlike for the regular iteration case. 950 // Give a warning if we seem to be looping forever. 951 952 if ((QueuedAllocationWarningCount > 0) && 953 (try_count % QueuedAllocationWarningCount == 0)) { 954 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 955 Thread::current()->name(), try_count, word_size); 956 } 957 } 958 959 ShouldNotReachHere(); 960 return NULL; 961 } 962 963 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 964 bool expect_null_mutator_alloc_region) { 965 assert_at_safepoint_on_vm_thread(); 966 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 967 "the current alloc region was unexpectedly found to be non-NULL"); 968 969 if (!is_humongous(word_size)) { 970 return _allocator->attempt_allocation_locked(word_size); 971 } else { 972 HeapWord* result = humongous_obj_allocate(word_size); 973 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 974 collector_state()->set_initiate_conc_mark_if_possible(true); 975 } 976 return result; 977 } 978 979 ShouldNotReachHere(); 980 } 981 982 class PostCompactionPrinterClosure: public HeapRegionClosure { 983 private: 984 G1HRPrinter* _hr_printer; 985 public: 986 bool do_heap_region(HeapRegion* hr) { 987 assert(!hr->is_young(), "not expecting to find young regions"); 988 _hr_printer->post_compaction(hr); 989 return false; 990 } 991 992 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 993 : _hr_printer(hr_printer) { } 994 }; 995 996 void G1CollectedHeap::print_hrm_post_compaction() { 997 if (_hr_printer.is_active()) { 998 PostCompactionPrinterClosure cl(hr_printer()); 999 heap_region_iterate(&cl); 1000 } 1001 } 1002 1003 void G1CollectedHeap::abort_concurrent_cycle() { 1004 // If we start the compaction before the CM threads finish 1005 // scanning the root regions we might trip them over as we'll 1006 // be moving objects / updating references. So let's wait until 1007 // they are done. By telling them to abort, they should complete 1008 // early. 1009 _cm->root_regions()->abort(); 1010 _cm->root_regions()->wait_until_scan_finished(); 1011 1012 // Disable discovery and empty the discovered lists 1013 // for the CM ref processor. 1014 _ref_processor_cm->disable_discovery(); 1015 _ref_processor_cm->abandon_partial_discovery(); 1016 _ref_processor_cm->verify_no_references_recorded(); 1017 1018 // Abandon current iterations of concurrent marking and concurrent 1019 // refinement, if any are in progress. 1020 concurrent_mark()->concurrent_cycle_abort(); 1021 } 1022 1023 void G1CollectedHeap::prepare_heap_for_full_collection() { 1024 // Make sure we'll choose a new allocation region afterwards. 1025 _allocator->release_mutator_alloc_region(); 1026 _allocator->abandon_gc_alloc_regions(); 1027 1028 // We may have added regions to the current incremental collection 1029 // set between the last GC or pause and now. We need to clear the 1030 // incremental collection set and then start rebuilding it afresh 1031 // after this full GC. 1032 abandon_collection_set(collection_set()); 1033 1034 tear_down_region_sets(false /* free_list_only */); 1035 1036 hrm()->prepare_for_full_collection_start(); 1037 } 1038 1039 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1040 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1041 assert_used_and_recalculate_used_equal(this); 1042 _verifier->verify_region_sets_optional(); 1043 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1044 _verifier->check_bitmaps("Full GC Start"); 1045 } 1046 1047 void G1CollectedHeap::prepare_heap_for_mutators() { 1048 hrm()->prepare_for_full_collection_end(); 1049 1050 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1051 ClassLoaderDataGraph::purge(); 1052 MetaspaceUtils::verify_metrics(); 1053 1054 // Prepare heap for normal collections. 1055 assert(num_free_regions() == 0, "we should not have added any free regions"); 1056 rebuild_region_sets(false /* free_list_only */); 1057 abort_refinement(); 1058 resize_heap_if_necessary(); 1059 1060 // Rebuild the strong code root lists for each region 1061 rebuild_strong_code_roots(); 1062 1063 // Purge code root memory 1064 purge_code_root_memory(); 1065 1066 // Start a new incremental collection set for the next pause 1067 start_new_collection_set(); 1068 1069 _allocator->init_mutator_alloc_region(); 1070 1071 // Post collection state updates. 1072 MetaspaceGC::compute_new_size(); 1073 } 1074 1075 void G1CollectedHeap::abort_refinement() { 1076 if (_hot_card_cache->use_cache()) { 1077 _hot_card_cache->reset_hot_cache(); 1078 } 1079 1080 // Discard all remembered set updates. 1081 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1082 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1083 "DCQS should be empty"); 1084 } 1085 1086 void G1CollectedHeap::verify_after_full_collection() { 1087 _hrm->verify_optional(); 1088 _verifier->verify_region_sets_optional(); 1089 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1090 // Clear the previous marking bitmap, if needed for bitmap verification. 1091 // Note we cannot do this when we clear the next marking bitmap in 1092 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1093 // objects marked during a full GC against the previous bitmap. 1094 // But we need to clear it before calling check_bitmaps below since 1095 // the full GC has compacted objects and updated TAMS but not updated 1096 // the prev bitmap. 1097 if (G1VerifyBitmaps) { 1098 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1099 _cm->clear_prev_bitmap(workers()); 1100 } 1101 // This call implicitly verifies that the next bitmap is clear after Full GC. 1102 _verifier->check_bitmaps("Full GC End"); 1103 1104 // At this point there should be no regions in the 1105 // entire heap tagged as young. 1106 assert(check_young_list_empty(), "young list should be empty at this point"); 1107 1108 // Note: since we've just done a full GC, concurrent 1109 // marking is no longer active. Therefore we need not 1110 // re-enable reference discovery for the CM ref processor. 1111 // That will be done at the start of the next marking cycle. 1112 // We also know that the STW processor should no longer 1113 // discover any new references. 1114 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1115 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1116 _ref_processor_stw->verify_no_references_recorded(); 1117 _ref_processor_cm->verify_no_references_recorded(); 1118 } 1119 1120 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1121 // Post collection logging. 1122 // We should do this after we potentially resize the heap so 1123 // that all the COMMIT / UNCOMMIT events are generated before 1124 // the compaction events. 1125 print_hrm_post_compaction(); 1126 heap_transition->print(); 1127 print_heap_after_gc(); 1128 print_heap_regions(); 1129 #ifdef TRACESPINNING 1130 ParallelTaskTerminator::print_termination_counts(); 1131 #endif 1132 } 1133 1134 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1135 bool clear_all_soft_refs) { 1136 assert_at_safepoint_on_vm_thread(); 1137 1138 if (GCLocker::check_active_before_gc()) { 1139 // Full GC was not completed. 1140 return false; 1141 } 1142 1143 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1144 soft_ref_policy()->should_clear_all_soft_refs(); 1145 1146 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1147 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1148 1149 collector.prepare_collection(); 1150 collector.collect(); 1151 collector.complete_collection(); 1152 1153 // Full collection was successfully completed. 1154 return true; 1155 } 1156 1157 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1158 // Currently, there is no facility in the do_full_collection(bool) API to notify 1159 // the caller that the collection did not succeed (e.g., because it was locked 1160 // out by the GC locker). So, right now, we'll ignore the return value. 1161 bool dummy = do_full_collection(true, /* explicit_gc */ 1162 clear_all_soft_refs); 1163 } 1164 1165 void G1CollectedHeap::resize_heap_if_necessary() { 1166 assert_at_safepoint_on_vm_thread(); 1167 1168 // Capacity, free and used after the GC counted as full regions to 1169 // include the waste in the following calculations. 1170 const size_t capacity_after_gc = capacity(); 1171 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1172 1173 // This is enforced in arguments.cpp. 1174 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1175 "otherwise the code below doesn't make sense"); 1176 1177 // We don't have floating point command-line arguments 1178 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1179 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1180 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1181 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1182 1183 // We have to be careful here as these two calculations can overflow 1184 // 32-bit size_t's. 1185 double used_after_gc_d = (double) used_after_gc; 1186 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1187 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1188 1189 // Let's make sure that they are both under the max heap size, which 1190 // by default will make them fit into a size_t. 1191 double desired_capacity_upper_bound = (double) MaxHeapSize; 1192 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1193 desired_capacity_upper_bound); 1194 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1195 desired_capacity_upper_bound); 1196 1197 // We can now safely turn them into size_t's. 1198 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1199 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1200 1201 // This assert only makes sense here, before we adjust them 1202 // with respect to the min and max heap size. 1203 assert(minimum_desired_capacity <= maximum_desired_capacity, 1204 "minimum_desired_capacity = " SIZE_FORMAT ", " 1205 "maximum_desired_capacity = " SIZE_FORMAT, 1206 minimum_desired_capacity, maximum_desired_capacity); 1207 1208 // Should not be greater than the heap max size. No need to adjust 1209 // it with respect to the heap min size as it's a lower bound (i.e., 1210 // we'll try to make the capacity larger than it, not smaller). 1211 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1212 // Should not be less than the heap min size. No need to adjust it 1213 // with respect to the heap max size as it's an upper bound (i.e., 1214 // we'll try to make the capacity smaller than it, not greater). 1215 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1216 1217 if (capacity_after_gc < minimum_desired_capacity) { 1218 // Don't expand unless it's significant 1219 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1220 1221 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1222 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1223 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1224 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1225 1226 expand(expand_bytes, _workers); 1227 1228 // No expansion, now see if we want to shrink 1229 } else if (capacity_after_gc > maximum_desired_capacity) { 1230 // Capacity too large, compute shrinking size 1231 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1232 1233 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1234 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1235 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1236 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1237 1238 shrink(shrink_bytes); 1239 } 1240 } 1241 1242 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1243 bool do_gc, 1244 bool clear_all_soft_refs, 1245 bool expect_null_mutator_alloc_region, 1246 bool* gc_succeeded) { 1247 *gc_succeeded = true; 1248 // Let's attempt the allocation first. 1249 HeapWord* result = 1250 attempt_allocation_at_safepoint(word_size, 1251 expect_null_mutator_alloc_region); 1252 if (result != NULL) { 1253 return result; 1254 } 1255 1256 // In a G1 heap, we're supposed to keep allocation from failing by 1257 // incremental pauses. Therefore, at least for now, we'll favor 1258 // expansion over collection. (This might change in the future if we can 1259 // do something smarter than full collection to satisfy a failed alloc.) 1260 result = expand_and_allocate(word_size); 1261 if (result != NULL) { 1262 return result; 1263 } 1264 1265 if (do_gc) { 1266 // Expansion didn't work, we'll try to do a Full GC. 1267 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1268 clear_all_soft_refs); 1269 } 1270 1271 return NULL; 1272 } 1273 1274 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1275 bool* succeeded) { 1276 assert_at_safepoint_on_vm_thread(); 1277 1278 // Attempts to allocate followed by Full GC. 1279 HeapWord* result = 1280 satisfy_failed_allocation_helper(word_size, 1281 true, /* do_gc */ 1282 false, /* clear_all_soft_refs */ 1283 false, /* expect_null_mutator_alloc_region */ 1284 succeeded); 1285 1286 if (result != NULL || !*succeeded) { 1287 return result; 1288 } 1289 1290 // Attempts to allocate followed by Full GC that will collect all soft references. 1291 result = satisfy_failed_allocation_helper(word_size, 1292 true, /* do_gc */ 1293 true, /* clear_all_soft_refs */ 1294 true, /* expect_null_mutator_alloc_region */ 1295 succeeded); 1296 1297 if (result != NULL || !*succeeded) { 1298 return result; 1299 } 1300 1301 // Attempts to allocate, no GC 1302 result = satisfy_failed_allocation_helper(word_size, 1303 false, /* do_gc */ 1304 false, /* clear_all_soft_refs */ 1305 true, /* expect_null_mutator_alloc_region */ 1306 succeeded); 1307 1308 if (result != NULL) { 1309 return result; 1310 } 1311 1312 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1313 "Flag should have been handled and cleared prior to this point"); 1314 1315 // What else? We might try synchronous finalization later. If the total 1316 // space available is large enough for the allocation, then a more 1317 // complete compaction phase than we've tried so far might be 1318 // appropriate. 1319 return NULL; 1320 } 1321 1322 // Attempting to expand the heap sufficiently 1323 // to support an allocation of the given "word_size". If 1324 // successful, perform the allocation and return the address of the 1325 // allocated block, or else "NULL". 1326 1327 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1328 assert_at_safepoint_on_vm_thread(); 1329 1330 _verifier->verify_region_sets_optional(); 1331 1332 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1333 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1334 word_size * HeapWordSize); 1335 1336 1337 if (expand(expand_bytes, _workers)) { 1338 _hrm->verify_optional(); 1339 _verifier->verify_region_sets_optional(); 1340 return attempt_allocation_at_safepoint(word_size, 1341 false /* expect_null_mutator_alloc_region */); 1342 } 1343 return NULL; 1344 } 1345 1346 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1347 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1348 aligned_expand_bytes = align_up(aligned_expand_bytes, 1349 HeapRegion::GrainBytes); 1350 1351 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1352 expand_bytes, aligned_expand_bytes); 1353 1354 if (is_maximal_no_gc()) { 1355 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1356 return false; 1357 } 1358 1359 double expand_heap_start_time_sec = os::elapsedTime(); 1360 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1361 assert(regions_to_expand > 0, "Must expand by at least one region"); 1362 1363 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1364 if (expand_time_ms != NULL) { 1365 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1366 } 1367 1368 if (expanded_by > 0) { 1369 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1370 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1371 policy()->record_new_heap_size(num_regions()); 1372 } else { 1373 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1374 1375 // The expansion of the virtual storage space was unsuccessful. 1376 // Let's see if it was because we ran out of swap. 1377 if (G1ExitOnExpansionFailure && 1378 _hrm->available() >= regions_to_expand) { 1379 // We had head room... 1380 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1381 } 1382 } 1383 return regions_to_expand > 0; 1384 } 1385 1386 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1387 size_t aligned_shrink_bytes = 1388 ReservedSpace::page_align_size_down(shrink_bytes); 1389 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1390 HeapRegion::GrainBytes); 1391 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1392 1393 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1394 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1395 1396 1397 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", 1398 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1399 if (num_regions_removed > 0) { 1400 policy()->record_new_heap_size(num_regions()); 1401 } else { 1402 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1403 } 1404 } 1405 1406 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1407 _verifier->verify_region_sets_optional(); 1408 1409 // We should only reach here at the end of a Full GC or during Remark which 1410 // means we should not not be holding to any GC alloc regions. The method 1411 // below will make sure of that and do any remaining clean up. 1412 _allocator->abandon_gc_alloc_regions(); 1413 1414 // Instead of tearing down / rebuilding the free lists here, we 1415 // could instead use the remove_all_pending() method on free_list to 1416 // remove only the ones that we need to remove. 1417 tear_down_region_sets(true /* free_list_only */); 1418 shrink_helper(shrink_bytes); 1419 rebuild_region_sets(true /* free_list_only */); 1420 1421 _hrm->verify_optional(); 1422 _verifier->verify_region_sets_optional(); 1423 } 1424 1425 class OldRegionSetChecker : public HeapRegionSetChecker { 1426 public: 1427 void check_mt_safety() { 1428 // Master Old Set MT safety protocol: 1429 // (a) If we're at a safepoint, operations on the master old set 1430 // should be invoked: 1431 // - by the VM thread (which will serialize them), or 1432 // - by the GC workers while holding the FreeList_lock, if we're 1433 // at a safepoint for an evacuation pause (this lock is taken 1434 // anyway when an GC alloc region is retired so that a new one 1435 // is allocated from the free list), or 1436 // - by the GC workers while holding the OldSets_lock, if we're at a 1437 // safepoint for a cleanup pause. 1438 // (b) If we're not at a safepoint, operations on the master old set 1439 // should be invoked while holding the Heap_lock. 1440 1441 if (SafepointSynchronize::is_at_safepoint()) { 1442 guarantee(Thread::current()->is_VM_thread() || 1443 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1444 "master old set MT safety protocol at a safepoint"); 1445 } else { 1446 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1447 } 1448 } 1449 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1450 const char* get_description() { return "Old Regions"; } 1451 }; 1452 1453 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1454 public: 1455 void check_mt_safety() { 1456 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1457 "May only change archive regions during initialization or safepoint."); 1458 } 1459 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1460 const char* get_description() { return "Archive Regions"; } 1461 }; 1462 1463 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1464 public: 1465 void check_mt_safety() { 1466 // Humongous Set MT safety protocol: 1467 // (a) If we're at a safepoint, operations on the master humongous 1468 // set should be invoked by either the VM thread (which will 1469 // serialize them) or by the GC workers while holding the 1470 // OldSets_lock. 1471 // (b) If we're not at a safepoint, operations on the master 1472 // humongous set should be invoked while holding the Heap_lock. 1473 1474 if (SafepointSynchronize::is_at_safepoint()) { 1475 guarantee(Thread::current()->is_VM_thread() || 1476 OldSets_lock->owned_by_self(), 1477 "master humongous set MT safety protocol at a safepoint"); 1478 } else { 1479 guarantee(Heap_lock->owned_by_self(), 1480 "master humongous set MT safety protocol outside a safepoint"); 1481 } 1482 } 1483 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1484 const char* get_description() { return "Humongous Regions"; } 1485 }; 1486 1487 G1CollectedHeap::G1CollectedHeap() : 1488 CollectedHeap(), 1489 _young_gen_sampling_thread(NULL), 1490 _workers(NULL), 1491 _card_table(NULL), 1492 _soft_ref_policy(), 1493 _old_set("Old Region Set", new OldRegionSetChecker()), 1494 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1495 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1496 _bot(NULL), 1497 _listener(), 1498 _hrm(NULL), 1499 _allocator(NULL), 1500 _verifier(NULL), 1501 _summary_bytes_used(0), 1502 _archive_allocator(NULL), 1503 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1504 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1505 _expand_heap_after_alloc_failure(true), 1506 _g1mm(NULL), 1507 _humongous_reclaim_candidates(), 1508 _has_humongous_reclaim_candidates(false), 1509 _hr_printer(), 1510 _collector_state(), 1511 _old_marking_cycles_started(0), 1512 _old_marking_cycles_completed(0), 1513 _eden(), 1514 _survivor(), 1515 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1516 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1517 _policy(G1Policy::create_policy(_gc_timer_stw)), 1518 _heap_sizing_policy(NULL), 1519 _collection_set(this, _policy), 1520 _hot_card_cache(NULL), 1521 _rem_set(NULL), 1522 _cm(NULL), 1523 _cm_thread(NULL), 1524 _cr(NULL), 1525 _task_queues(NULL), 1526 _evacuation_failed(false), 1527 _evacuation_failed_info_array(NULL), 1528 _preserved_marks_set(true /* in_c_heap */), 1529 #ifndef PRODUCT 1530 _evacuation_failure_alot_for_current_gc(false), 1531 _evacuation_failure_alot_gc_number(0), 1532 _evacuation_failure_alot_count(0), 1533 #endif 1534 _ref_processor_stw(NULL), 1535 _is_alive_closure_stw(this), 1536 _is_subject_to_discovery_stw(this), 1537 _ref_processor_cm(NULL), 1538 _is_alive_closure_cm(this), 1539 _is_subject_to_discovery_cm(this), 1540 _region_attr() { 1541 1542 _verifier = new G1HeapVerifier(this); 1543 1544 _allocator = new G1Allocator(this); 1545 1546 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1547 1548 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1549 1550 // Override the default _filler_array_max_size so that no humongous filler 1551 // objects are created. 1552 _filler_array_max_size = _humongous_object_threshold_in_words; 1553 1554 uint n_queues = ParallelGCThreads; 1555 _task_queues = new RefToScanQueueSet(n_queues); 1556 1557 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1558 1559 for (uint i = 0; i < n_queues; i++) { 1560 RefToScanQueue* q = new RefToScanQueue(); 1561 q->initialize(); 1562 _task_queues->register_queue(i, q); 1563 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1564 } 1565 1566 // Initialize the G1EvacuationFailureALot counters and flags. 1567 NOT_PRODUCT(reset_evacuation_should_fail();) 1568 _gc_tracer_stw->initialize(); 1569 1570 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1571 } 1572 1573 static size_t actual_reserved_page_size(ReservedSpace rs) { 1574 size_t page_size = os::vm_page_size(); 1575 if (UseLargePages) { 1576 // There are two ways to manage large page memory. 1577 // 1. OS supports committing large page memory. 1578 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1579 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1580 // we reserved memory without large page. 1581 if (os::can_commit_large_page_memory() || rs.special()) { 1582 // An alignment at ReservedSpace comes from preferred page size or 1583 // heap alignment, and if the alignment came from heap alignment, it could be 1584 // larger than large pages size. So need to cap with the large page size. 1585 page_size = MIN2(rs.alignment(), os::large_page_size()); 1586 } 1587 } 1588 1589 return page_size; 1590 } 1591 1592 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1593 size_t size, 1594 size_t translation_factor) { 1595 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1596 // Allocate a new reserved space, preferring to use large pages. 1597 ReservedSpace rs(size, preferred_page_size); 1598 size_t page_size = actual_reserved_page_size(rs); 1599 G1RegionToSpaceMapper* result = 1600 G1RegionToSpaceMapper::create_mapper(rs, 1601 size, 1602 page_size, 1603 HeapRegion::GrainBytes, 1604 translation_factor, 1605 mtGC); 1606 1607 os::trace_page_sizes_for_requested_size(description, 1608 size, 1609 preferred_page_size, 1610 page_size, 1611 rs.base(), 1612 rs.size()); 1613 1614 return result; 1615 } 1616 1617 jint G1CollectedHeap::initialize_concurrent_refinement() { 1618 jint ecode = JNI_OK; 1619 _cr = G1ConcurrentRefine::create(&ecode); 1620 return ecode; 1621 } 1622 1623 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1624 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1625 if (_young_gen_sampling_thread->osthread() == NULL) { 1626 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1627 return JNI_ENOMEM; 1628 } 1629 return JNI_OK; 1630 } 1631 1632 jint G1CollectedHeap::initialize() { 1633 os::enable_vtime(); 1634 1635 // Necessary to satisfy locking discipline assertions. 1636 1637 MutexLocker x(Heap_lock); 1638 1639 // While there are no constraints in the GC code that HeapWordSize 1640 // be any particular value, there are multiple other areas in the 1641 // system which believe this to be true (e.g. oop->object_size in some 1642 // cases incorrectly returns the size in wordSize units rather than 1643 // HeapWordSize). 1644 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1645 1646 size_t init_byte_size = InitialHeapSize; 1647 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1648 1649 // Ensure that the sizes are properly aligned. 1650 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1651 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1652 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1653 1654 // Reserve the maximum. 1655 1656 // When compressed oops are enabled, the preferred heap base 1657 // is calculated by subtracting the requested size from the 1658 // 32Gb boundary and using the result as the base address for 1659 // heap reservation. If the requested size is not aligned to 1660 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1661 // into the ReservedHeapSpace constructor) then the actual 1662 // base of the reserved heap may end up differing from the 1663 // address that was requested (i.e. the preferred heap base). 1664 // If this happens then we could end up using a non-optimal 1665 // compressed oops mode. 1666 1667 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1668 HeapAlignment); 1669 1670 initialize_reserved_region(heap_rs); 1671 1672 // Create the barrier set for the entire reserved region. 1673 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1674 ct->initialize(); 1675 G1BarrierSet* bs = new G1BarrierSet(ct); 1676 bs->initialize(); 1677 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1678 BarrierSet::set_barrier_set(bs); 1679 _card_table = ct; 1680 1681 { 1682 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1683 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1684 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1685 } 1686 1687 // Create the hot card cache. 1688 _hot_card_cache = new G1HotCardCache(this); 1689 1690 // Carve out the G1 part of the heap. 1691 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1692 size_t page_size = actual_reserved_page_size(heap_rs); 1693 G1RegionToSpaceMapper* heap_storage = 1694 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1695 g1_rs.size(), 1696 page_size, 1697 HeapRegion::GrainBytes, 1698 1, 1699 mtJavaHeap); 1700 if(heap_storage == NULL) { 1701 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1702 return JNI_ERR; 1703 } 1704 1705 os::trace_page_sizes("Heap", 1706 MinHeapSize, 1707 reserved_byte_size, 1708 page_size, 1709 heap_rs.base(), 1710 heap_rs.size()); 1711 heap_storage->set_mapping_changed_listener(&_listener); 1712 1713 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1714 G1RegionToSpaceMapper* bot_storage = 1715 create_aux_memory_mapper("Block Offset Table", 1716 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1717 G1BlockOffsetTable::heap_map_factor()); 1718 1719 G1RegionToSpaceMapper* cardtable_storage = 1720 create_aux_memory_mapper("Card Table", 1721 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1722 G1CardTable::heap_map_factor()); 1723 1724 G1RegionToSpaceMapper* card_counts_storage = 1725 create_aux_memory_mapper("Card Counts Table", 1726 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1727 G1CardCounts::heap_map_factor()); 1728 1729 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1730 G1RegionToSpaceMapper* prev_bitmap_storage = 1731 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1732 G1RegionToSpaceMapper* next_bitmap_storage = 1733 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1734 1735 _hrm = HeapRegionManager::create_manager(this); 1736 1737 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1738 _card_table->initialize(cardtable_storage); 1739 1740 // Do later initialization work for concurrent refinement. 1741 _hot_card_cache->initialize(card_counts_storage); 1742 1743 // 6843694 - ensure that the maximum region index can fit 1744 // in the remembered set structures. 1745 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1746 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1747 1748 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1749 // start within the first card. 1750 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1751 // Also create a G1 rem set. 1752 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1753 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1754 1755 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1756 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1757 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1758 "too many cards per region"); 1759 1760 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1761 1762 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1763 1764 { 1765 HeapWord* start = _hrm->reserved().start(); 1766 HeapWord* end = _hrm->reserved().end(); 1767 size_t granularity = HeapRegion::GrainBytes; 1768 1769 _region_attr.initialize(start, end, granularity); 1770 _humongous_reclaim_candidates.initialize(start, end, granularity); 1771 } 1772 1773 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1774 true /* are_GC_task_threads */, 1775 false /* are_ConcurrentGC_threads */); 1776 if (_workers == NULL) { 1777 return JNI_ENOMEM; 1778 } 1779 _workers->initialize_workers(); 1780 1781 // Create the G1ConcurrentMark data structure and thread. 1782 // (Must do this late, so that "max_regions" is defined.) 1783 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1784 if (_cm == NULL || !_cm->completed_initialization()) { 1785 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1786 return JNI_ENOMEM; 1787 } 1788 _cm_thread = _cm->cm_thread(); 1789 1790 // Now expand into the initial heap size. 1791 if (!expand(init_byte_size, _workers)) { 1792 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1793 return JNI_ENOMEM; 1794 } 1795 1796 // Perform any initialization actions delegated to the policy. 1797 policy()->init(this, &_collection_set); 1798 1799 jint ecode = initialize_concurrent_refinement(); 1800 if (ecode != JNI_OK) { 1801 return ecode; 1802 } 1803 1804 ecode = initialize_young_gen_sampling_thread(); 1805 if (ecode != JNI_OK) { 1806 return ecode; 1807 } 1808 1809 { 1810 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1811 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1812 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1813 } 1814 1815 // Here we allocate the dummy HeapRegion that is required by the 1816 // G1AllocRegion class. 1817 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1818 1819 // We'll re-use the same region whether the alloc region will 1820 // require BOT updates or not and, if it doesn't, then a non-young 1821 // region will complain that it cannot support allocations without 1822 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1823 dummy_region->set_eden(); 1824 // Make sure it's full. 1825 dummy_region->set_top(dummy_region->end()); 1826 G1AllocRegion::setup(this, dummy_region); 1827 1828 _allocator->init_mutator_alloc_region(); 1829 1830 // Do create of the monitoring and management support so that 1831 // values in the heap have been properly initialized. 1832 _g1mm = new G1MonitoringSupport(this); 1833 1834 G1StringDedup::initialize(); 1835 1836 _preserved_marks_set.init(ParallelGCThreads); 1837 1838 _collection_set.initialize(max_regions()); 1839 1840 return JNI_OK; 1841 } 1842 1843 void G1CollectedHeap::stop() { 1844 // Stop all concurrent threads. We do this to make sure these threads 1845 // do not continue to execute and access resources (e.g. logging) 1846 // that are destroyed during shutdown. 1847 _cr->stop(); 1848 _young_gen_sampling_thread->stop(); 1849 _cm_thread->stop(); 1850 if (G1StringDedup::is_enabled()) { 1851 G1StringDedup::stop(); 1852 } 1853 } 1854 1855 void G1CollectedHeap::safepoint_synchronize_begin() { 1856 SuspendibleThreadSet::synchronize(); 1857 } 1858 1859 void G1CollectedHeap::safepoint_synchronize_end() { 1860 SuspendibleThreadSet::desynchronize(); 1861 } 1862 1863 void G1CollectedHeap::post_initialize() { 1864 CollectedHeap::post_initialize(); 1865 ref_processing_init(); 1866 } 1867 1868 void G1CollectedHeap::ref_processing_init() { 1869 // Reference processing in G1 currently works as follows: 1870 // 1871 // * There are two reference processor instances. One is 1872 // used to record and process discovered references 1873 // during concurrent marking; the other is used to 1874 // record and process references during STW pauses 1875 // (both full and incremental). 1876 // * Both ref processors need to 'span' the entire heap as 1877 // the regions in the collection set may be dotted around. 1878 // 1879 // * For the concurrent marking ref processor: 1880 // * Reference discovery is enabled at initial marking. 1881 // * Reference discovery is disabled and the discovered 1882 // references processed etc during remarking. 1883 // * Reference discovery is MT (see below). 1884 // * Reference discovery requires a barrier (see below). 1885 // * Reference processing may or may not be MT 1886 // (depending on the value of ParallelRefProcEnabled 1887 // and ParallelGCThreads). 1888 // * A full GC disables reference discovery by the CM 1889 // ref processor and abandons any entries on it's 1890 // discovered lists. 1891 // 1892 // * For the STW processor: 1893 // * Non MT discovery is enabled at the start of a full GC. 1894 // * Processing and enqueueing during a full GC is non-MT. 1895 // * During a full GC, references are processed after marking. 1896 // 1897 // * Discovery (may or may not be MT) is enabled at the start 1898 // of an incremental evacuation pause. 1899 // * References are processed near the end of a STW evacuation pause. 1900 // * For both types of GC: 1901 // * Discovery is atomic - i.e. not concurrent. 1902 // * Reference discovery will not need a barrier. 1903 1904 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1905 1906 // Concurrent Mark ref processor 1907 _ref_processor_cm = 1908 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1909 mt_processing, // mt processing 1910 ParallelGCThreads, // degree of mt processing 1911 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1912 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1913 false, // Reference discovery is not atomic 1914 &_is_alive_closure_cm, // is alive closure 1915 true); // allow changes to number of processing threads 1916 1917 // STW ref processor 1918 _ref_processor_stw = 1919 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1920 mt_processing, // mt processing 1921 ParallelGCThreads, // degree of mt processing 1922 (ParallelGCThreads > 1), // mt discovery 1923 ParallelGCThreads, // degree of mt discovery 1924 true, // Reference discovery is atomic 1925 &_is_alive_closure_stw, // is alive closure 1926 true); // allow changes to number of processing threads 1927 } 1928 1929 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1930 return &_soft_ref_policy; 1931 } 1932 1933 size_t G1CollectedHeap::capacity() const { 1934 return _hrm->length() * HeapRegion::GrainBytes; 1935 } 1936 1937 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1938 return _hrm->total_free_bytes(); 1939 } 1940 1941 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1942 _hot_card_cache->drain(cl, worker_id); 1943 } 1944 1945 // Computes the sum of the storage used by the various regions. 1946 size_t G1CollectedHeap::used() const { 1947 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1948 if (_archive_allocator != NULL) { 1949 result += _archive_allocator->used(); 1950 } 1951 return result; 1952 } 1953 1954 size_t G1CollectedHeap::used_unlocked() const { 1955 return _summary_bytes_used; 1956 } 1957 1958 class SumUsedClosure: public HeapRegionClosure { 1959 size_t _used; 1960 public: 1961 SumUsedClosure() : _used(0) {} 1962 bool do_heap_region(HeapRegion* r) { 1963 _used += r->used(); 1964 return false; 1965 } 1966 size_t result() { return _used; } 1967 }; 1968 1969 size_t G1CollectedHeap::recalculate_used() const { 1970 SumUsedClosure blk; 1971 heap_region_iterate(&blk); 1972 return blk.result(); 1973 } 1974 1975 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1976 switch (cause) { 1977 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1978 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1979 case GCCause::_wb_conc_mark: return true; 1980 default : return false; 1981 } 1982 } 1983 1984 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1985 switch (cause) { 1986 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1987 case GCCause::_g1_humongous_allocation: return true; 1988 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1989 default: return is_user_requested_concurrent_full_gc(cause); 1990 } 1991 } 1992 1993 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 1994 if(policy()->force_upgrade_to_full()) { 1995 return true; 1996 } else if (should_do_concurrent_full_gc(_gc_cause)) { 1997 return false; 1998 } else if (has_regions_left_for_allocation()) { 1999 return false; 2000 } else { 2001 return true; 2002 } 2003 } 2004 2005 #ifndef PRODUCT 2006 void G1CollectedHeap::allocate_dummy_regions() { 2007 // Let's fill up most of the region 2008 size_t word_size = HeapRegion::GrainWords - 1024; 2009 // And as a result the region we'll allocate will be humongous. 2010 guarantee(is_humongous(word_size), "sanity"); 2011 2012 // _filler_array_max_size is set to humongous object threshold 2013 // but temporarily change it to use CollectedHeap::fill_with_object(). 2014 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2015 2016 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2017 // Let's use the existing mechanism for the allocation 2018 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2019 if (dummy_obj != NULL) { 2020 MemRegion mr(dummy_obj, word_size); 2021 CollectedHeap::fill_with_object(mr); 2022 } else { 2023 // If we can't allocate once, we probably cannot allocate 2024 // again. Let's get out of the loop. 2025 break; 2026 } 2027 } 2028 } 2029 #endif // !PRODUCT 2030 2031 void G1CollectedHeap::increment_old_marking_cycles_started() { 2032 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2033 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2034 "Wrong marking cycle count (started: %d, completed: %d)", 2035 _old_marking_cycles_started, _old_marking_cycles_completed); 2036 2037 _old_marking_cycles_started++; 2038 } 2039 2040 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2041 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2042 2043 // We assume that if concurrent == true, then the caller is a 2044 // concurrent thread that was joined the Suspendible Thread 2045 // Set. If there's ever a cheap way to check this, we should add an 2046 // assert here. 2047 2048 // Given that this method is called at the end of a Full GC or of a 2049 // concurrent cycle, and those can be nested (i.e., a Full GC can 2050 // interrupt a concurrent cycle), the number of full collections 2051 // completed should be either one (in the case where there was no 2052 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2053 // behind the number of full collections started. 2054 2055 // This is the case for the inner caller, i.e. a Full GC. 2056 assert(concurrent || 2057 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2058 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2059 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2060 "is inconsistent with _old_marking_cycles_completed = %u", 2061 _old_marking_cycles_started, _old_marking_cycles_completed); 2062 2063 // This is the case for the outer caller, i.e. the concurrent cycle. 2064 assert(!concurrent || 2065 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2066 "for outer caller (concurrent cycle): " 2067 "_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 _old_marking_cycles_completed += 1; 2072 2073 // We need to clear the "in_progress" flag in the CM thread before 2074 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2075 // is set) so that if a waiter requests another System.gc() it doesn't 2076 // incorrectly see that a marking cycle is still in progress. 2077 if (concurrent) { 2078 _cm_thread->set_idle(); 2079 } 2080 2081 // This notify_all() will ensure that a thread that called 2082 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2083 // and it's waiting for a full GC to finish will be woken up. It is 2084 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2085 FullGCCount_lock->notify_all(); 2086 } 2087 2088 void G1CollectedHeap::collect(GCCause::Cause cause) { 2089 try_collect(cause, true); 2090 } 2091 2092 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2093 assert_heap_not_locked(); 2094 2095 bool gc_succeeded; 2096 bool should_retry_gc; 2097 2098 do { 2099 should_retry_gc = false; 2100 2101 uint gc_count_before; 2102 uint old_marking_count_before; 2103 uint full_gc_count_before; 2104 2105 { 2106 MutexLocker ml(Heap_lock); 2107 2108 // Read the GC count while holding the Heap_lock 2109 gc_count_before = total_collections(); 2110 full_gc_count_before = total_full_collections(); 2111 old_marking_count_before = _old_marking_cycles_started; 2112 } 2113 2114 if (should_do_concurrent_full_gc(cause)) { 2115 // Schedule an initial-mark evacuation pause that will start a 2116 // concurrent cycle. We're setting word_size to 0 which means that 2117 // we are not requesting a post-GC allocation. 2118 VM_G1CollectForAllocation op(0, /* word_size */ 2119 gc_count_before, 2120 cause, 2121 true, /* should_initiate_conc_mark */ 2122 policy()->max_pause_time_ms()); 2123 VMThread::execute(&op); 2124 gc_succeeded = op.gc_succeeded(); 2125 if (!gc_succeeded && retry_on_gc_failure) { 2126 if (old_marking_count_before == _old_marking_cycles_started) { 2127 should_retry_gc = op.should_retry_gc(); 2128 } else { 2129 // A Full GC happened while we were trying to schedule the 2130 // concurrent cycle. No point in starting a new cycle given 2131 // that the whole heap was collected anyway. 2132 } 2133 2134 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2135 GCLocker::stall_until_clear(); 2136 } 2137 } 2138 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2139 // Return false to be consistent with VMOp failure due to 2140 // another collection slipping in after our gc_count but before 2141 // our request is processed. _gc_locker collections upgraded by 2142 // GCLockerInvokesConcurrent are handled above and never discarded. 2143 return false; 2144 } else { 2145 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2146 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2147 2148 // Schedule a standard evacuation pause. We're setting word_size 2149 // to 0 which means that we are not requesting a post-GC allocation. 2150 VM_G1CollectForAllocation op(0, /* word_size */ 2151 gc_count_before, 2152 cause, 2153 false, /* should_initiate_conc_mark */ 2154 policy()->max_pause_time_ms()); 2155 VMThread::execute(&op); 2156 gc_succeeded = op.gc_succeeded(); 2157 } else { 2158 // Schedule a Full GC. 2159 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2160 VMThread::execute(&op); 2161 gc_succeeded = op.gc_succeeded(); 2162 } 2163 } 2164 } while (should_retry_gc); 2165 return gc_succeeded; 2166 } 2167 2168 bool G1CollectedHeap::is_in(const void* p) const { 2169 if (_hrm->reserved().contains(p)) { 2170 // Given that we know that p is in the reserved space, 2171 // heap_region_containing() should successfully 2172 // return the containing region. 2173 HeapRegion* hr = heap_region_containing(p); 2174 return hr->is_in(p); 2175 } else { 2176 return false; 2177 } 2178 } 2179 2180 #ifdef ASSERT 2181 bool G1CollectedHeap::is_in_exact(const void* p) const { 2182 bool contains = reserved_region().contains(p); 2183 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2184 if (contains && available) { 2185 return true; 2186 } else { 2187 return false; 2188 } 2189 } 2190 #endif 2191 2192 // Iteration functions. 2193 2194 // Iterates an ObjectClosure over all objects within a HeapRegion. 2195 2196 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2197 ObjectClosure* _cl; 2198 public: 2199 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2200 bool do_heap_region(HeapRegion* r) { 2201 if (!r->is_continues_humongous()) { 2202 r->object_iterate(_cl); 2203 } 2204 return false; 2205 } 2206 }; 2207 2208 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2209 IterateObjectClosureRegionClosure blk(cl); 2210 heap_region_iterate(&blk); 2211 } 2212 2213 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2214 _hrm->iterate(cl); 2215 } 2216 2217 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2218 HeapRegionClaimer *hrclaimer, 2219 uint worker_id) const { 2220 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2221 } 2222 2223 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2224 HeapRegionClaimer *hrclaimer) const { 2225 _hrm->par_iterate(cl, hrclaimer, 0); 2226 } 2227 2228 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2229 _collection_set.iterate(cl); 2230 } 2231 2232 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2233 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2234 } 2235 2236 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2237 HeapRegion* hr = heap_region_containing(addr); 2238 return hr->block_start(addr); 2239 } 2240 2241 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2242 HeapRegion* hr = heap_region_containing(addr); 2243 return hr->block_is_obj(addr); 2244 } 2245 2246 bool G1CollectedHeap::supports_tlab_allocation() const { 2247 return true; 2248 } 2249 2250 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2251 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2252 } 2253 2254 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2255 return _eden.length() * HeapRegion::GrainBytes; 2256 } 2257 2258 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2259 // must be equal to the humongous object limit. 2260 size_t G1CollectedHeap::max_tlab_size() const { 2261 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2262 } 2263 2264 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2265 return _allocator->unsafe_max_tlab_alloc(); 2266 } 2267 2268 size_t G1CollectedHeap::max_capacity() const { 2269 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2270 } 2271 2272 size_t G1CollectedHeap::max_reserved_capacity() const { 2273 return _hrm->max_length() * HeapRegion::GrainBytes; 2274 } 2275 2276 jlong G1CollectedHeap::millis_since_last_gc() { 2277 // See the notes in GenCollectedHeap::millis_since_last_gc() 2278 // for more information about the implementation. 2279 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2280 _policy->collection_pause_end_millis(); 2281 if (ret_val < 0) { 2282 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2283 ". returning zero instead.", ret_val); 2284 return 0; 2285 } 2286 return ret_val; 2287 } 2288 2289 void G1CollectedHeap::deduplicate_string(oop str) { 2290 assert(java_lang_String::is_instance(str), "invariant"); 2291 2292 if (G1StringDedup::is_enabled()) { 2293 G1StringDedup::deduplicate(str); 2294 } 2295 } 2296 2297 void G1CollectedHeap::prepare_for_verify() { 2298 _verifier->prepare_for_verify(); 2299 } 2300 2301 void G1CollectedHeap::verify(VerifyOption vo) { 2302 _verifier->verify(vo); 2303 } 2304 2305 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2306 return true; 2307 } 2308 2309 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2310 return _cm_thread->request_concurrent_phase(phase); 2311 } 2312 2313 bool G1CollectedHeap::is_heterogeneous_heap() const { 2314 return G1Arguments::is_heterogeneous_heap(); 2315 } 2316 2317 class PrintRegionClosure: public HeapRegionClosure { 2318 outputStream* _st; 2319 public: 2320 PrintRegionClosure(outputStream* st) : _st(st) {} 2321 bool do_heap_region(HeapRegion* r) { 2322 r->print_on(_st); 2323 return false; 2324 } 2325 }; 2326 2327 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2328 const HeapRegion* hr, 2329 const VerifyOption vo) const { 2330 switch (vo) { 2331 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2332 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2333 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2334 default: ShouldNotReachHere(); 2335 } 2336 return false; // keep some compilers happy 2337 } 2338 2339 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2340 const VerifyOption vo) const { 2341 switch (vo) { 2342 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2343 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2344 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2345 default: ShouldNotReachHere(); 2346 } 2347 return false; // keep some compilers happy 2348 } 2349 2350 void G1CollectedHeap::print_heap_regions() const { 2351 LogTarget(Trace, gc, heap, region) lt; 2352 if (lt.is_enabled()) { 2353 LogStream ls(lt); 2354 print_regions_on(&ls); 2355 } 2356 } 2357 2358 void G1CollectedHeap::print_on(outputStream* st) const { 2359 st->print(" %-20s", "garbage-first heap"); 2360 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2361 capacity()/K, used_unlocked()/K); 2362 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2363 p2i(_hrm->reserved().start()), 2364 p2i(_hrm->reserved().end())); 2365 st->cr(); 2366 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2367 uint young_regions = young_regions_count(); 2368 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2369 (size_t) young_regions * HeapRegion::GrainBytes / K); 2370 uint survivor_regions = survivor_regions_count(); 2371 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2372 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2373 st->cr(); 2374 MetaspaceUtils::print_on(st); 2375 } 2376 2377 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2378 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2379 "HS=humongous(starts), HC=humongous(continues), " 2380 "CS=collection set, F=free, " 2381 "OA=open archive, CA=closed archive, " 2382 "TAMS=top-at-mark-start (previous, next)"); 2383 PrintRegionClosure blk(st); 2384 heap_region_iterate(&blk); 2385 } 2386 2387 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2388 print_on(st); 2389 2390 // Print the per-region information. 2391 print_regions_on(st); 2392 } 2393 2394 void G1CollectedHeap::print_on_error(outputStream* st) const { 2395 this->CollectedHeap::print_on_error(st); 2396 2397 if (_cm != NULL) { 2398 st->cr(); 2399 _cm->print_on_error(st); 2400 } 2401 } 2402 2403 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2404 workers()->print_worker_threads_on(st); 2405 _cm_thread->print_on(st); 2406 st->cr(); 2407 _cm->print_worker_threads_on(st); 2408 _cr->print_threads_on(st); 2409 _young_gen_sampling_thread->print_on(st); 2410 if (G1StringDedup::is_enabled()) { 2411 G1StringDedup::print_worker_threads_on(st); 2412 } 2413 } 2414 2415 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2416 workers()->threads_do(tc); 2417 tc->do_thread(_cm_thread); 2418 _cm->threads_do(tc); 2419 _cr->threads_do(tc); 2420 tc->do_thread(_young_gen_sampling_thread); 2421 if (G1StringDedup::is_enabled()) { 2422 G1StringDedup::threads_do(tc); 2423 } 2424 } 2425 2426 void G1CollectedHeap::print_tracing_info() const { 2427 rem_set()->print_summary_info(); 2428 concurrent_mark()->print_summary_info(); 2429 } 2430 2431 #ifndef PRODUCT 2432 // Helpful for debugging RSet issues. 2433 2434 class PrintRSetsClosure : public HeapRegionClosure { 2435 private: 2436 const char* _msg; 2437 size_t _occupied_sum; 2438 2439 public: 2440 bool do_heap_region(HeapRegion* r) { 2441 HeapRegionRemSet* hrrs = r->rem_set(); 2442 size_t occupied = hrrs->occupied(); 2443 _occupied_sum += occupied; 2444 2445 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2446 if (occupied == 0) { 2447 tty->print_cr(" RSet is empty"); 2448 } else { 2449 hrrs->print(); 2450 } 2451 tty->print_cr("----------"); 2452 return false; 2453 } 2454 2455 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2456 tty->cr(); 2457 tty->print_cr("========================================"); 2458 tty->print_cr("%s", msg); 2459 tty->cr(); 2460 } 2461 2462 ~PrintRSetsClosure() { 2463 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2464 tty->print_cr("========================================"); 2465 tty->cr(); 2466 } 2467 }; 2468 2469 void G1CollectedHeap::print_cset_rsets() { 2470 PrintRSetsClosure cl("Printing CSet RSets"); 2471 collection_set_iterate_all(&cl); 2472 } 2473 2474 void G1CollectedHeap::print_all_rsets() { 2475 PrintRSetsClosure cl("Printing All RSets");; 2476 heap_region_iterate(&cl); 2477 } 2478 #endif // PRODUCT 2479 2480 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2481 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2482 } 2483 2484 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2485 2486 size_t eden_used_bytes = _eden.used_bytes(); 2487 size_t survivor_used_bytes = _survivor.used_bytes(); 2488 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2489 2490 size_t eden_capacity_bytes = 2491 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2492 2493 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2494 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2495 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2496 } 2497 2498 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2499 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2500 stats->unused(), stats->used(), stats->region_end_waste(), 2501 stats->regions_filled(), stats->direct_allocated(), 2502 stats->failure_used(), stats->failure_waste()); 2503 } 2504 2505 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2506 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2507 gc_tracer->report_gc_heap_summary(when, heap_summary); 2508 2509 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2510 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2511 } 2512 2513 G1CollectedHeap* G1CollectedHeap::heap() { 2514 CollectedHeap* heap = Universe::heap(); 2515 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2516 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2517 return (G1CollectedHeap*)heap; 2518 } 2519 2520 void G1CollectedHeap::gc_prologue(bool full) { 2521 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2522 2523 // This summary needs to be printed before incrementing total collections. 2524 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2525 2526 // Update common counters. 2527 increment_total_collections(full /* full gc */); 2528 if (full || collector_state()->in_initial_mark_gc()) { 2529 increment_old_marking_cycles_started(); 2530 } 2531 2532 // Fill TLAB's and such 2533 double start = os::elapsedTime(); 2534 ensure_parsability(true); 2535 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2536 } 2537 2538 void G1CollectedHeap::gc_epilogue(bool full) { 2539 // Update common counters. 2540 if (full) { 2541 // Update the number of full collections that have been completed. 2542 increment_old_marking_cycles_completed(false /* concurrent */); 2543 } 2544 2545 // We are at the end of the GC. Total collections has already been increased. 2546 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2547 2548 // FIXME: what is this about? 2549 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2550 // is set. 2551 #if COMPILER2_OR_JVMCI 2552 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2553 #endif 2554 2555 double start = os::elapsedTime(); 2556 resize_all_tlabs(); 2557 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2558 2559 MemoryService::track_memory_usage(); 2560 // We have just completed a GC. Update the soft reference 2561 // policy with the new heap occupancy 2562 Universe::update_heap_info_at_gc(); 2563 } 2564 2565 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2566 uint gc_count_before, 2567 bool* succeeded, 2568 GCCause::Cause gc_cause) { 2569 assert_heap_not_locked_and_not_at_safepoint(); 2570 VM_G1CollectForAllocation op(word_size, 2571 gc_count_before, 2572 gc_cause, 2573 false, /* should_initiate_conc_mark */ 2574 policy()->max_pause_time_ms()); 2575 VMThread::execute(&op); 2576 2577 HeapWord* result = op.result(); 2578 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2579 assert(result == NULL || ret_succeeded, 2580 "the result should be NULL if the VM did not succeed"); 2581 *succeeded = ret_succeeded; 2582 2583 assert_heap_not_locked(); 2584 return result; 2585 } 2586 2587 void G1CollectedHeap::do_concurrent_mark() { 2588 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2589 if (!_cm_thread->in_progress()) { 2590 _cm_thread->set_started(); 2591 CGC_lock->notify(); 2592 } 2593 } 2594 2595 size_t G1CollectedHeap::pending_card_num() { 2596 struct CountCardsClosure : public ThreadClosure { 2597 size_t _cards; 2598 CountCardsClosure() : _cards(0) {} 2599 virtual void do_thread(Thread* t) { 2600 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2601 } 2602 } count_from_threads; 2603 Threads::threads_do(&count_from_threads); 2604 2605 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2606 dcqs.verify_num_cards(); 2607 2608 return dcqs.num_cards() + count_from_threads._cards; 2609 } 2610 2611 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2612 // We don't nominate objects with many remembered set entries, on 2613 // the assumption that such objects are likely still live. 2614 HeapRegionRemSet* rem_set = r->rem_set(); 2615 2616 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2617 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2618 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2619 } 2620 2621 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2622 private: 2623 size_t _total_humongous; 2624 size_t _candidate_humongous; 2625 2626 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2627 assert(region->is_starts_humongous(), "Must start a humongous object"); 2628 2629 oop obj = oop(region->bottom()); 2630 2631 // Dead objects cannot be eager reclaim candidates. Due to class 2632 // unloading it is unsafe to query their classes so we return early. 2633 if (g1h->is_obj_dead(obj, region)) { 2634 return false; 2635 } 2636 2637 // If we do not have a complete remembered set for the region, then we can 2638 // not be sure that we have all references to it. 2639 if (!region->rem_set()->is_complete()) { 2640 return false; 2641 } 2642 // Candidate selection must satisfy the following constraints 2643 // while concurrent marking is in progress: 2644 // 2645 // * In order to maintain SATB invariants, an object must not be 2646 // reclaimed if it was allocated before the start of marking and 2647 // has not had its references scanned. Such an object must have 2648 // its references (including type metadata) scanned to ensure no 2649 // live objects are missed by the marking process. Objects 2650 // allocated after the start of concurrent marking don't need to 2651 // be scanned. 2652 // 2653 // * An object must not be reclaimed if it is on the concurrent 2654 // mark stack. Objects allocated after the start of concurrent 2655 // marking are never pushed on the mark stack. 2656 // 2657 // Nominating only objects allocated after the start of concurrent 2658 // marking is sufficient to meet both constraints. This may miss 2659 // some objects that satisfy the constraints, but the marking data 2660 // structures don't support efficiently performing the needed 2661 // additional tests or scrubbing of the mark stack. 2662 // 2663 // However, we presently only nominate is_typeArray() objects. 2664 // A humongous object containing references induces remembered 2665 // set entries on other regions. In order to reclaim such an 2666 // object, those remembered sets would need to be cleaned up. 2667 // 2668 // We also treat is_typeArray() objects specially, allowing them 2669 // to be reclaimed even if allocated before the start of 2670 // concurrent mark. For this we rely on mark stack insertion to 2671 // exclude is_typeArray() objects, preventing reclaiming an object 2672 // that is in the mark stack. We also rely on the metadata for 2673 // such objects to be built-in and so ensured to be kept live. 2674 // Frequent allocation and drop of large binary blobs is an 2675 // important use case for eager reclaim, and this special handling 2676 // may reduce needed headroom. 2677 2678 return obj->is_typeArray() && 2679 g1h->is_potential_eager_reclaim_candidate(region); 2680 } 2681 2682 public: 2683 RegisterRegionsWithRegionAttrTableClosure() 2684 : _total_humongous(0), 2685 _candidate_humongous(0) { 2686 } 2687 2688 virtual bool do_heap_region(HeapRegion* r) { 2689 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2690 2691 if (!r->is_starts_humongous()) { 2692 g1h->register_region_with_region_attr(r); 2693 return false; 2694 } 2695 2696 bool is_candidate = humongous_region_is_candidate(g1h, r); 2697 uint rindex = r->hrm_index(); 2698 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2699 if (is_candidate) { 2700 g1h->register_humongous_region_with_region_attr(rindex); 2701 _candidate_humongous++; 2702 // We will later handle the remembered sets of these regions. 2703 } else { 2704 g1h->register_region_with_region_attr(r); 2705 } 2706 _total_humongous++; 2707 2708 return false; 2709 } 2710 2711 size_t total_humongous() const { return _total_humongous; } 2712 size_t candidate_humongous() const { return _candidate_humongous; } 2713 }; 2714 2715 void G1CollectedHeap::register_regions_with_region_attr() { 2716 Ticks start = Ticks::now(); 2717 2718 RegisterRegionsWithRegionAttrTableClosure cl; 2719 heap_region_iterate(&cl); 2720 2721 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2722 cl.total_humongous(), 2723 cl.candidate_humongous()); 2724 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2725 } 2726 2727 #ifndef PRODUCT 2728 void G1CollectedHeap::verify_region_attr_remset_update() { 2729 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2730 public: 2731 virtual bool do_heap_region(HeapRegion* r) { 2732 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2733 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2734 assert(r->rem_set()->is_tracked() == needs_remset_update, 2735 "Region %u remset tracking status (%s) different to region attribute (%s)", 2736 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2737 return false; 2738 } 2739 } cl; 2740 heap_region_iterate(&cl); 2741 } 2742 #endif 2743 2744 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2745 public: 2746 bool do_heap_region(HeapRegion* hr) { 2747 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2748 hr->verify_rem_set(); 2749 } 2750 return false; 2751 } 2752 }; 2753 2754 uint G1CollectedHeap::num_task_queues() const { 2755 return _task_queues->size(); 2756 } 2757 2758 #if TASKQUEUE_STATS 2759 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2760 st->print_raw_cr("GC Task Stats"); 2761 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2762 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2763 } 2764 2765 void G1CollectedHeap::print_taskqueue_stats() const { 2766 if (!log_is_enabled(Trace, gc, task, stats)) { 2767 return; 2768 } 2769 Log(gc, task, stats) log; 2770 ResourceMark rm; 2771 LogStream ls(log.trace()); 2772 outputStream* st = &ls; 2773 2774 print_taskqueue_stats_hdr(st); 2775 2776 TaskQueueStats totals; 2777 const uint n = num_task_queues(); 2778 for (uint i = 0; i < n; ++i) { 2779 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2780 totals += task_queue(i)->stats; 2781 } 2782 st->print_raw("tot "); totals.print(st); st->cr(); 2783 2784 DEBUG_ONLY(totals.verify()); 2785 } 2786 2787 void G1CollectedHeap::reset_taskqueue_stats() { 2788 const uint n = num_task_queues(); 2789 for (uint i = 0; i < n; ++i) { 2790 task_queue(i)->stats.reset(); 2791 } 2792 } 2793 #endif // TASKQUEUE_STATS 2794 2795 void G1CollectedHeap::wait_for_root_region_scanning() { 2796 double scan_wait_start = os::elapsedTime(); 2797 // We have to wait until the CM threads finish scanning the 2798 // root regions as it's the only way to ensure that all the 2799 // objects on them have been correctly scanned before we start 2800 // moving them during the GC. 2801 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2802 double wait_time_ms = 0.0; 2803 if (waited) { 2804 double scan_wait_end = os::elapsedTime(); 2805 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2806 } 2807 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2808 } 2809 2810 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2811 private: 2812 G1HRPrinter* _hr_printer; 2813 public: 2814 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2815 2816 virtual bool do_heap_region(HeapRegion* r) { 2817 _hr_printer->cset(r); 2818 return false; 2819 } 2820 }; 2821 2822 void G1CollectedHeap::start_new_collection_set() { 2823 double start = os::elapsedTime(); 2824 2825 collection_set()->start_incremental_building(); 2826 2827 clear_region_attr(); 2828 2829 guarantee(_eden.length() == 0, "eden should have been cleared"); 2830 policy()->transfer_survivors_to_cset(survivor()); 2831 2832 // We redo the verification but now wrt to the new CSet which 2833 // has just got initialized after the previous CSet was freed. 2834 _cm->verify_no_collection_set_oops(); 2835 2836 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2837 } 2838 2839 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2840 2841 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2842 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2843 collection_set()->optional_region_length()); 2844 2845 _cm->verify_no_collection_set_oops(); 2846 2847 if (_hr_printer.is_active()) { 2848 G1PrintCollectionSetClosure cl(&_hr_printer); 2849 _collection_set.iterate(&cl); 2850 _collection_set.iterate_optional(&cl); 2851 } 2852 } 2853 2854 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2855 if (collector_state()->in_initial_mark_gc()) { 2856 return G1HeapVerifier::G1VerifyConcurrentStart; 2857 } else if (collector_state()->in_young_only_phase()) { 2858 return G1HeapVerifier::G1VerifyYoungNormal; 2859 } else { 2860 return G1HeapVerifier::G1VerifyMixed; 2861 } 2862 } 2863 2864 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2865 if (VerifyRememberedSets) { 2866 log_info(gc, verify)("[Verifying RemSets before GC]"); 2867 VerifyRegionRemSetClosure v_cl; 2868 heap_region_iterate(&v_cl); 2869 } 2870 _verifier->verify_before_gc(type); 2871 _verifier->check_bitmaps("GC Start"); 2872 } 2873 2874 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2875 if (VerifyRememberedSets) { 2876 log_info(gc, verify)("[Verifying RemSets after GC]"); 2877 VerifyRegionRemSetClosure v_cl; 2878 heap_region_iterate(&v_cl); 2879 } 2880 _verifier->verify_after_gc(type); 2881 _verifier->check_bitmaps("GC End"); 2882 } 2883 2884 void G1CollectedHeap::expand_heap_after_young_collection(){ 2885 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2886 if (expand_bytes > 0) { 2887 // No need for an ergo logging here, 2888 // expansion_amount() does this when it returns a value > 0. 2889 double expand_ms; 2890 if (!expand(expand_bytes, _workers, &expand_ms)) { 2891 // We failed to expand the heap. Cannot do anything about it. 2892 } 2893 phase_times()->record_expand_heap_time(expand_ms); 2894 } 2895 } 2896 2897 const char* G1CollectedHeap::young_gc_name() const { 2898 if (collector_state()->in_initial_mark_gc()) { 2899 return "Pause Young (Concurrent Start)"; 2900 } else if (collector_state()->in_young_only_phase()) { 2901 if (collector_state()->in_young_gc_before_mixed()) { 2902 return "Pause Young (Prepare Mixed)"; 2903 } else { 2904 return "Pause Young (Normal)"; 2905 } 2906 } else { 2907 return "Pause Young (Mixed)"; 2908 } 2909 } 2910 2911 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2912 assert_at_safepoint_on_vm_thread(); 2913 guarantee(!is_gc_active(), "collection is not reentrant"); 2914 2915 if (GCLocker::check_active_before_gc()) { 2916 return false; 2917 } 2918 2919 GCIdMark gc_id_mark; 2920 2921 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2922 ResourceMark rm; 2923 2924 policy()->note_gc_start(); 2925 2926 _gc_timer_stw->register_gc_start(); 2927 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2928 2929 wait_for_root_region_scanning(); 2930 2931 print_heap_before_gc(); 2932 print_heap_regions(); 2933 trace_heap_before_gc(_gc_tracer_stw); 2934 2935 _verifier->verify_region_sets_optional(); 2936 _verifier->verify_dirty_young_regions(); 2937 2938 // We should not be doing initial mark unless the conc mark thread is running 2939 if (!_cm_thread->should_terminate()) { 2940 // This call will decide whether this pause is an initial-mark 2941 // pause. If it is, in_initial_mark_gc() will return true 2942 // for the duration of this pause. 2943 policy()->decide_on_conc_mark_initiation(); 2944 } 2945 2946 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2947 assert(!collector_state()->in_initial_mark_gc() || 2948 collector_state()->in_young_only_phase(), "sanity"); 2949 // We also do not allow mixed GCs during marking. 2950 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2951 2952 // Record whether this pause is an initial mark. When the current 2953 // thread has completed its logging output and it's safe to signal 2954 // the CM thread, the flag's value in the policy has been reset. 2955 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2956 if (should_start_conc_mark) { 2957 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2958 } 2959 2960 // Inner scope for scope based logging, timers, and stats collection 2961 { 2962 G1EvacuationInfo evacuation_info; 2963 2964 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2965 2966 GCTraceCPUTime tcpu; 2967 2968 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 2969 2970 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2971 workers()->active_workers(), 2972 Threads::number_of_non_daemon_threads()); 2973 active_workers = workers()->update_active_workers(active_workers); 2974 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2975 2976 G1MonitoringScope ms(g1mm(), 2977 false /* full_gc */, 2978 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2979 2980 G1HeapTransition heap_transition(this); 2981 size_t heap_used_bytes_before_gc = used(); 2982 2983 { 2984 IsGCActiveMark x; 2985 2986 gc_prologue(false); 2987 2988 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 2989 verify_before_young_collection(verify_type); 2990 2991 { 2992 // The elapsed time induced by the start time below deliberately elides 2993 // the possible verification above. 2994 double sample_start_time_sec = os::elapsedTime(); 2995 2996 // Please see comment in g1CollectedHeap.hpp and 2997 // G1CollectedHeap::ref_processing_init() to see how 2998 // reference processing currently works in G1. 2999 _ref_processor_stw->enable_discovery(); 3000 3001 // We want to temporarily turn off discovery by the 3002 // CM ref processor, if necessary, and turn it back on 3003 // on again later if we do. Using a scoped 3004 // NoRefDiscovery object will do this. 3005 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3006 3007 policy()->record_collection_pause_start(sample_start_time_sec); 3008 3009 // Forget the current allocation region (we might even choose it to be part 3010 // of the collection set!). 3011 _allocator->release_mutator_alloc_region(); 3012 3013 calculate_collection_set(evacuation_info, target_pause_time_ms); 3014 3015 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3016 G1ParScanThreadStateSet per_thread_states(this, 3017 &rdcqs, 3018 workers()->active_workers(), 3019 collection_set()->young_region_length(), 3020 collection_set()->optional_region_length()); 3021 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3022 3023 // Actually do the work... 3024 evacuate_initial_collection_set(&per_thread_states); 3025 3026 if (_collection_set.optional_region_length() != 0) { 3027 evacuate_optional_collection_set(&per_thread_states); 3028 } 3029 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3030 3031 start_new_collection_set(); 3032 3033 _survivor_evac_stats.adjust_desired_plab_sz(); 3034 _old_evac_stats.adjust_desired_plab_sz(); 3035 3036 if (should_start_conc_mark) { 3037 // We have to do this before we notify the CM threads that 3038 // they can start working to make sure that all the 3039 // appropriate initialization is done on the CM object. 3040 concurrent_mark()->post_initial_mark(); 3041 // Note that we don't actually trigger the CM thread at 3042 // this point. We do that later when we're sure that 3043 // the current thread has completed its logging output. 3044 } 3045 3046 allocate_dummy_regions(); 3047 3048 _allocator->init_mutator_alloc_region(); 3049 3050 expand_heap_after_young_collection(); 3051 3052 double sample_end_time_sec = os::elapsedTime(); 3053 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3054 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc); 3055 } 3056 3057 verify_after_young_collection(verify_type); 3058 3059 #ifdef TRACESPINNING 3060 ParallelTaskTerminator::print_termination_counts(); 3061 #endif 3062 3063 gc_epilogue(false); 3064 } 3065 3066 // Print the remainder of the GC log output. 3067 if (evacuation_failed()) { 3068 log_info(gc)("To-space exhausted"); 3069 } 3070 3071 policy()->print_phases(); 3072 heap_transition.print(); 3073 3074 _hrm->verify_optional(); 3075 _verifier->verify_region_sets_optional(); 3076 3077 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3078 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3079 3080 print_heap_after_gc(); 3081 print_heap_regions(); 3082 trace_heap_after_gc(_gc_tracer_stw); 3083 3084 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3085 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3086 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3087 // before any GC notifications are raised. 3088 g1mm()->update_sizes(); 3089 3090 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3091 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3092 _gc_timer_stw->register_gc_end(); 3093 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3094 } 3095 // It should now be safe to tell the concurrent mark thread to start 3096 // without its logging output interfering with the logging output 3097 // that came from the pause. 3098 3099 if (should_start_conc_mark) { 3100 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3101 // thread(s) could be running concurrently with us. Make sure that anything 3102 // after this point does not assume that we are the only GC thread running. 3103 // Note: of course, the actual marking work will not start until the safepoint 3104 // itself is released in SuspendibleThreadSet::desynchronize(). 3105 do_concurrent_mark(); 3106 } 3107 3108 return true; 3109 } 3110 3111 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3112 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3113 workers()->run_task(&rsfp_task); 3114 } 3115 3116 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3117 double remove_self_forwards_start = os::elapsedTime(); 3118 3119 remove_self_forwarding_pointers(rdcqs); 3120 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3121 _preserved_marks_set.restore(&task_executor); 3122 3123 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3124 } 3125 3126 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3127 if (!_evacuation_failed) { 3128 _evacuation_failed = true; 3129 } 3130 3131 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3132 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3133 } 3134 3135 bool G1ParEvacuateFollowersClosure::offer_termination() { 3136 EventGCPhaseParallel event; 3137 G1ParScanThreadState* const pss = par_scan_state(); 3138 start_term_time(); 3139 const bool res = terminator()->offer_termination(); 3140 end_term_time(); 3141 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3142 return res; 3143 } 3144 3145 void G1ParEvacuateFollowersClosure::do_void() { 3146 EventGCPhaseParallel event; 3147 G1ParScanThreadState* const pss = par_scan_state(); 3148 pss->trim_queue(); 3149 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3150 do { 3151 EventGCPhaseParallel event; 3152 pss->steal_and_trim_queue(queues()); 3153 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3154 } while (!offer_termination()); 3155 } 3156 3157 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3158 bool class_unloading_occurred) { 3159 uint num_workers = workers()->active_workers(); 3160 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3161 workers()->run_task(&unlink_task); 3162 } 3163 3164 // Clean string dedup data structures. 3165 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3166 // record the durations of the phases. Hence the almost-copy. 3167 class G1StringDedupCleaningTask : public AbstractGangTask { 3168 BoolObjectClosure* _is_alive; 3169 OopClosure* _keep_alive; 3170 G1GCPhaseTimes* _phase_times; 3171 3172 public: 3173 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3174 OopClosure* keep_alive, 3175 G1GCPhaseTimes* phase_times) : 3176 AbstractGangTask("Partial Cleaning Task"), 3177 _is_alive(is_alive), 3178 _keep_alive(keep_alive), 3179 _phase_times(phase_times) 3180 { 3181 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3182 StringDedup::gc_prologue(true); 3183 } 3184 3185 ~G1StringDedupCleaningTask() { 3186 StringDedup::gc_epilogue(); 3187 } 3188 3189 void work(uint worker_id) { 3190 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3191 { 3192 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3193 StringDedupQueue::unlink_or_oops_do(&cl); 3194 } 3195 { 3196 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3197 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3198 } 3199 } 3200 }; 3201 3202 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3203 OopClosure* keep_alive, 3204 G1GCPhaseTimes* phase_times) { 3205 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3206 workers()->run_task(&cl); 3207 } 3208 3209 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3210 private: 3211 G1RedirtyCardsQueueSet* _qset; 3212 G1CollectedHeap* _g1h; 3213 BufferNode* volatile _nodes; 3214 3215 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3216 size_t buffer_size = _qset->buffer_size(); 3217 BufferNode* next = Atomic::load(&_nodes); 3218 while (next != NULL) { 3219 BufferNode* node = next; 3220 next = Atomic::cmpxchg(node->next(), &_nodes, node); 3221 if (next == node) { 3222 cl->apply_to_buffer(node, buffer_size, worker_id); 3223 next = node->next(); 3224 } 3225 } 3226 } 3227 3228 public: 3229 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3230 AbstractGangTask("Redirty Cards"), 3231 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3232 3233 virtual void work(uint worker_id) { 3234 G1GCPhaseTimes* p = _g1h->phase_times(); 3235 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3236 3237 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3238 par_apply(&cl, worker_id); 3239 3240 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3241 } 3242 }; 3243 3244 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3245 double redirty_logged_cards_start = os::elapsedTime(); 3246 3247 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3248 workers()->run_task(&redirty_task); 3249 3250 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3251 dcq.merge_bufferlists(rdcqs); 3252 3253 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3254 } 3255 3256 // Weak Reference Processing support 3257 3258 bool G1STWIsAliveClosure::do_object_b(oop p) { 3259 // An object is reachable if it is outside the collection set, 3260 // or is inside and copied. 3261 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3262 } 3263 3264 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3265 assert(obj != NULL, "must not be NULL"); 3266 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3267 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3268 // may falsely indicate that this is not the case here: however the collection set only 3269 // contains old regions when concurrent mark is not running. 3270 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3271 } 3272 3273 // Non Copying Keep Alive closure 3274 class G1KeepAliveClosure: public OopClosure { 3275 G1CollectedHeap*_g1h; 3276 public: 3277 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3278 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3279 void do_oop(oop* p) { 3280 oop obj = *p; 3281 assert(obj != NULL, "the caller should have filtered out NULL values"); 3282 3283 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3284 if (!region_attr.is_in_cset_or_humongous()) { 3285 return; 3286 } 3287 if (region_attr.is_in_cset()) { 3288 assert( obj->is_forwarded(), "invariant" ); 3289 *p = obj->forwardee(); 3290 } else { 3291 assert(!obj->is_forwarded(), "invariant" ); 3292 assert(region_attr.is_humongous(), 3293 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3294 _g1h->set_humongous_is_live(obj); 3295 } 3296 } 3297 }; 3298 3299 // Copying Keep Alive closure - can be called from both 3300 // serial and parallel code as long as different worker 3301 // threads utilize different G1ParScanThreadState instances 3302 // and different queues. 3303 3304 class G1CopyingKeepAliveClosure: public OopClosure { 3305 G1CollectedHeap* _g1h; 3306 G1ParScanThreadState* _par_scan_state; 3307 3308 public: 3309 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3310 G1ParScanThreadState* pss): 3311 _g1h(g1h), 3312 _par_scan_state(pss) 3313 {} 3314 3315 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3316 virtual void do_oop( oop* p) { do_oop_work(p); } 3317 3318 template <class T> void do_oop_work(T* p) { 3319 oop obj = RawAccess<>::oop_load(p); 3320 3321 if (_g1h->is_in_cset_or_humongous(obj)) { 3322 // If the referent object has been forwarded (either copied 3323 // to a new location or to itself in the event of an 3324 // evacuation failure) then we need to update the reference 3325 // field and, if both reference and referent are in the G1 3326 // heap, update the RSet for the referent. 3327 // 3328 // If the referent has not been forwarded then we have to keep 3329 // it alive by policy. Therefore we have copy the referent. 3330 // 3331 // When the queue is drained (after each phase of reference processing) 3332 // the object and it's followers will be copied, the reference field set 3333 // to point to the new location, and the RSet updated. 3334 _par_scan_state->push_on_queue(p); 3335 } 3336 } 3337 }; 3338 3339 // Serial drain queue closure. Called as the 'complete_gc' 3340 // closure for each discovered list in some of the 3341 // reference processing phases. 3342 3343 class G1STWDrainQueueClosure: public VoidClosure { 3344 protected: 3345 G1CollectedHeap* _g1h; 3346 G1ParScanThreadState* _par_scan_state; 3347 3348 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3349 3350 public: 3351 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3352 _g1h(g1h), 3353 _par_scan_state(pss) 3354 { } 3355 3356 void do_void() { 3357 G1ParScanThreadState* const pss = par_scan_state(); 3358 pss->trim_queue(); 3359 } 3360 }; 3361 3362 // Parallel Reference Processing closures 3363 3364 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3365 // processing during G1 evacuation pauses. 3366 3367 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3368 private: 3369 G1CollectedHeap* _g1h; 3370 G1ParScanThreadStateSet* _pss; 3371 RefToScanQueueSet* _queues; 3372 WorkGang* _workers; 3373 3374 public: 3375 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3376 G1ParScanThreadStateSet* per_thread_states, 3377 WorkGang* workers, 3378 RefToScanQueueSet *task_queues) : 3379 _g1h(g1h), 3380 _pss(per_thread_states), 3381 _queues(task_queues), 3382 _workers(workers) 3383 { 3384 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3385 } 3386 3387 // Executes the given task using concurrent marking worker threads. 3388 virtual void execute(ProcessTask& task, uint ergo_workers); 3389 }; 3390 3391 // Gang task for possibly parallel reference processing 3392 3393 class G1STWRefProcTaskProxy: public AbstractGangTask { 3394 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3395 ProcessTask& _proc_task; 3396 G1CollectedHeap* _g1h; 3397 G1ParScanThreadStateSet* _pss; 3398 RefToScanQueueSet* _task_queues; 3399 ParallelTaskTerminator* _terminator; 3400 3401 public: 3402 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3403 G1CollectedHeap* g1h, 3404 G1ParScanThreadStateSet* per_thread_states, 3405 RefToScanQueueSet *task_queues, 3406 ParallelTaskTerminator* terminator) : 3407 AbstractGangTask("Process reference objects in parallel"), 3408 _proc_task(proc_task), 3409 _g1h(g1h), 3410 _pss(per_thread_states), 3411 _task_queues(task_queues), 3412 _terminator(terminator) 3413 {} 3414 3415 virtual void work(uint worker_id) { 3416 // The reference processing task executed by a single worker. 3417 ResourceMark rm; 3418 HandleMark hm; 3419 3420 G1STWIsAliveClosure is_alive(_g1h); 3421 3422 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3423 pss->set_ref_discoverer(NULL); 3424 3425 // Keep alive closure. 3426 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3427 3428 // Complete GC closure 3429 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3430 3431 // Call the reference processing task's work routine. 3432 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3433 3434 // Note we cannot assert that the refs array is empty here as not all 3435 // of the processing tasks (specifically phase2 - pp2_work) execute 3436 // the complete_gc closure (which ordinarily would drain the queue) so 3437 // the queue may not be empty. 3438 } 3439 }; 3440 3441 // Driver routine for parallel reference processing. 3442 // Creates an instance of the ref processing gang 3443 // task and has the worker threads execute it. 3444 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3445 assert(_workers != NULL, "Need parallel worker threads."); 3446 3447 assert(_workers->active_workers() >= ergo_workers, 3448 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3449 ergo_workers, _workers->active_workers()); 3450 TaskTerminator terminator(ergo_workers, _queues); 3451 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3452 3453 _workers->run_task(&proc_task_proxy, ergo_workers); 3454 } 3455 3456 // End of weak reference support closures 3457 3458 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3459 double ref_proc_start = os::elapsedTime(); 3460 3461 ReferenceProcessor* rp = _ref_processor_stw; 3462 assert(rp->discovery_enabled(), "should have been enabled"); 3463 3464 // Closure to test whether a referent is alive. 3465 G1STWIsAliveClosure is_alive(this); 3466 3467 // Even when parallel reference processing is enabled, the processing 3468 // of JNI refs is serial and performed serially by the current thread 3469 // rather than by a worker. The following PSS will be used for processing 3470 // JNI refs. 3471 3472 // Use only a single queue for this PSS. 3473 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3474 pss->set_ref_discoverer(NULL); 3475 assert(pss->queue_is_empty(), "pre-condition"); 3476 3477 // Keep alive closure. 3478 G1CopyingKeepAliveClosure keep_alive(this, pss); 3479 3480 // Serial Complete GC closure 3481 G1STWDrainQueueClosure drain_queue(this, pss); 3482 3483 // Setup the soft refs policy... 3484 rp->setup_policy(false); 3485 3486 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3487 3488 ReferenceProcessorStats stats; 3489 if (!rp->processing_is_mt()) { 3490 // Serial reference processing... 3491 stats = rp->process_discovered_references(&is_alive, 3492 &keep_alive, 3493 &drain_queue, 3494 NULL, 3495 pt); 3496 } else { 3497 uint no_of_gc_workers = workers()->active_workers(); 3498 3499 // Parallel reference processing 3500 assert(no_of_gc_workers <= rp->max_num_queues(), 3501 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3502 no_of_gc_workers, rp->max_num_queues()); 3503 3504 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3505 stats = rp->process_discovered_references(&is_alive, 3506 &keep_alive, 3507 &drain_queue, 3508 &par_task_executor, 3509 pt); 3510 } 3511 3512 _gc_tracer_stw->report_gc_reference_stats(stats); 3513 3514 // We have completed copying any necessary live referent objects. 3515 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3516 3517 make_pending_list_reachable(); 3518 3519 assert(!rp->discovery_enabled(), "Postcondition"); 3520 rp->verify_no_references_recorded(); 3521 3522 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3523 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3524 } 3525 3526 void G1CollectedHeap::make_pending_list_reachable() { 3527 if (collector_state()->in_initial_mark_gc()) { 3528 oop pll_head = Universe::reference_pending_list(); 3529 if (pll_head != NULL) { 3530 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3531 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3532 } 3533 } 3534 } 3535 3536 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3537 double merge_pss_time_start = os::elapsedTime(); 3538 per_thread_states->flush(); 3539 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3540 } 3541 3542 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3543 _expand_heap_after_alloc_failure = true; 3544 _evacuation_failed = false; 3545 3546 // Disable the hot card cache. 3547 _hot_card_cache->reset_hot_cache_claimed_index(); 3548 _hot_card_cache->set_use_cache(false); 3549 3550 // Initialize the GC alloc regions. 3551 _allocator->init_gc_alloc_regions(evacuation_info); 3552 3553 { 3554 Ticks start = Ticks::now(); 3555 rem_set()->prepare_for_scan_heap_roots(); 3556 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3557 } 3558 3559 register_regions_with_region_attr(); 3560 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3561 3562 _preserved_marks_set.assert_empty(); 3563 3564 #if COMPILER2_OR_JVMCI 3565 DerivedPointerTable::clear(); 3566 #endif 3567 3568 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3569 if (collector_state()->in_initial_mark_gc()) { 3570 concurrent_mark()->pre_initial_mark(); 3571 3572 double start_clear_claimed_marks = os::elapsedTime(); 3573 3574 ClassLoaderDataGraph::clear_claimed_marks(); 3575 3576 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3577 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3578 } 3579 3580 // Should G1EvacuationFailureALot be in effect for this GC? 3581 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3582 } 3583 3584 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3585 protected: 3586 G1CollectedHeap* _g1h; 3587 G1ParScanThreadStateSet* _per_thread_states; 3588 RefToScanQueueSet* _task_queues; 3589 TaskTerminator _terminator; 3590 uint _num_workers; 3591 3592 void evacuate_live_objects(G1ParScanThreadState* pss, 3593 uint worker_id, 3594 G1GCPhaseTimes::GCParPhases objcopy_phase, 3595 G1GCPhaseTimes::GCParPhases termination_phase) { 3596 G1GCPhaseTimes* p = _g1h->phase_times(); 3597 3598 Ticks start = Ticks::now(); 3599 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase); 3600 cl.do_void(); 3601 3602 assert(pss->queue_is_empty(), "should be empty"); 3603 3604 Tickspan evac_time = (Ticks::now() - start); 3605 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3606 3607 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste); 3608 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste); 3609 3610 if (termination_phase == G1GCPhaseTimes::Termination) { 3611 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3612 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3613 } else { 3614 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3615 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3616 } 3617 } 3618 3619 virtual void start_work(uint worker_id) { } 3620 3621 virtual void end_work(uint worker_id) { } 3622 3623 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3624 3625 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3626 3627 public: 3628 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3629 AbstractGangTask(name), 3630 _g1h(G1CollectedHeap::heap()), 3631 _per_thread_states(per_thread_states), 3632 _task_queues(task_queues), 3633 _terminator(num_workers, _task_queues), 3634 _num_workers(num_workers) 3635 { } 3636 3637 void work(uint worker_id) { 3638 start_work(worker_id); 3639 3640 { 3641 ResourceMark rm; 3642 HandleMark hm; 3643 3644 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3645 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3646 3647 scan_roots(pss, worker_id); 3648 evacuate_live_objects(pss, worker_id); 3649 } 3650 3651 end_work(worker_id); 3652 } 3653 }; 3654 3655 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3656 G1RootProcessor* _root_processor; 3657 3658 void verify_trim_ticks(G1ParScanThreadState* pss, const char* location) { 3659 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation at %s %.3lf " JLONG_FORMAT, location, pss->trim_ticks().seconds(), pss->trim_ticks().value()); 3660 } 3661 3662 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3663 _root_processor->evacuate_roots(pss, worker_id); 3664 verify_trim_ticks(pss, "roots"); 3665 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3666 verify_trim_ticks(pss, "heap roots"); 3667 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3668 verify_trim_ticks(pss, "scan cset"); 3669 } 3670 3671 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3672 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3673 verify_trim_ticks(pss, "evac live"); 3674 } 3675 3676 void start_work(uint worker_id) { 3677 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3678 } 3679 3680 void end_work(uint worker_id) { 3681 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3682 } 3683 3684 public: 3685 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3686 G1ParScanThreadStateSet* per_thread_states, 3687 RefToScanQueueSet* task_queues, 3688 G1RootProcessor* root_processor, 3689 uint num_workers) : 3690 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3691 _root_processor(root_processor) 3692 { } 3693 }; 3694 3695 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3696 G1GCPhaseTimes* p = phase_times(); 3697 3698 { 3699 Ticks start = Ticks::now(); 3700 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3701 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3702 } 3703 3704 Tickspan task_time; 3705 const uint num_workers = workers()->active_workers(); 3706 3707 Ticks start_processing = Ticks::now(); 3708 { 3709 G1RootProcessor root_processor(this, num_workers); 3710 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3711 task_time = run_task(&g1_par_task); 3712 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3713 // To extract its code root fixup time we measure total time of this scope and 3714 // subtract from the time the WorkGang task took. 3715 } 3716 Tickspan total_processing = Ticks::now() - start_processing; 3717 3718 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3719 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3720 } 3721 3722 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3723 3724 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3725 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3726 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3727 } 3728 3729 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3730 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3731 } 3732 3733 public: 3734 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3735 RefToScanQueueSet* queues, 3736 uint num_workers) : 3737 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3738 } 3739 }; 3740 3741 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3742 class G1MarkScope : public MarkScope { }; 3743 3744 Tickspan task_time; 3745 3746 Ticks start_processing = Ticks::now(); 3747 { 3748 G1MarkScope code_mark_scope; 3749 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3750 task_time = run_task(&task); 3751 // See comment in evacuate_collection_set() for the reason of the scope. 3752 } 3753 Tickspan total_processing = Ticks::now() - start_processing; 3754 3755 G1GCPhaseTimes* p = phase_times(); 3756 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3757 } 3758 3759 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3760 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3761 3762 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3763 3764 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3765 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3766 3767 if (time_left_ms < 0 || 3768 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3769 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3770 _collection_set.optional_region_length(), time_left_ms); 3771 break; 3772 } 3773 3774 { 3775 Ticks start = Ticks::now(); 3776 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3777 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3778 } 3779 3780 { 3781 Ticks start = Ticks::now(); 3782 evacuate_next_optional_regions(per_thread_states); 3783 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3784 } 3785 } 3786 3787 _collection_set.abandon_optional_collection_set(per_thread_states); 3788 } 3789 3790 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3791 G1RedirtyCardsQueueSet* rdcqs, 3792 G1ParScanThreadStateSet* per_thread_states) { 3793 rem_set()->cleanup_after_scan_heap_roots(); 3794 3795 // Process any discovered reference objects - we have 3796 // to do this _before_ we retire the GC alloc regions 3797 // as we may have to copy some 'reachable' referent 3798 // objects (and their reachable sub-graphs) that were 3799 // not copied during the pause. 3800 process_discovered_references(per_thread_states); 3801 3802 G1STWIsAliveClosure is_alive(this); 3803 G1KeepAliveClosure keep_alive(this); 3804 3805 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3806 phase_times()->weak_phase_times()); 3807 3808 if (G1StringDedup::is_enabled()) { 3809 double string_dedup_time_ms = os::elapsedTime(); 3810 3811 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3812 3813 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3814 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3815 } 3816 3817 _allocator->release_gc_alloc_regions(evacuation_info); 3818 3819 if (evacuation_failed()) { 3820 restore_after_evac_failure(rdcqs); 3821 3822 // Reset the G1EvacuationFailureALot counters and flags 3823 NOT_PRODUCT(reset_evacuation_should_fail();) 3824 3825 double recalculate_used_start = os::elapsedTime(); 3826 set_used(recalculate_used()); 3827 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3828 3829 if (_archive_allocator != NULL) { 3830 _archive_allocator->clear_used(); 3831 } 3832 for (uint i = 0; i < ParallelGCThreads; i++) { 3833 if (_evacuation_failed_info_array[i].has_failed()) { 3834 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3835 } 3836 } 3837 } else { 3838 // The "used" of the the collection set have already been subtracted 3839 // when they were freed. Add in the bytes evacuated. 3840 increase_used(policy()->bytes_copied_during_gc()); 3841 } 3842 3843 _preserved_marks_set.assert_empty(); 3844 3845 merge_per_thread_state_info(per_thread_states); 3846 3847 // Reset and re-enable the hot card cache. 3848 // Note the counts for the cards in the regions in the 3849 // collection set are reset when the collection set is freed. 3850 _hot_card_cache->reset_hot_cache(); 3851 _hot_card_cache->set_use_cache(true); 3852 3853 purge_code_root_memory(); 3854 3855 redirty_logged_cards(rdcqs); 3856 3857 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3858 3859 eagerly_reclaim_humongous_regions(); 3860 3861 record_obj_copy_mem_stats(); 3862 3863 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3864 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3865 3866 #if COMPILER2_OR_JVMCI 3867 double start = os::elapsedTime(); 3868 DerivedPointerTable::update_pointers(); 3869 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3870 #endif 3871 policy()->print_age_table(); 3872 } 3873 3874 void G1CollectedHeap::record_obj_copy_mem_stats() { 3875 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3876 3877 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3878 create_g1_evac_summary(&_old_evac_stats)); 3879 } 3880 3881 void G1CollectedHeap::free_region(HeapRegion* hr, 3882 FreeRegionList* free_list, 3883 bool skip_remset, 3884 bool skip_hot_card_cache, 3885 bool locked) { 3886 assert(!hr->is_free(), "the region should not be free"); 3887 assert(!hr->is_empty(), "the region should not be empty"); 3888 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3889 assert(free_list != NULL, "pre-condition"); 3890 3891 if (G1VerifyBitmaps) { 3892 MemRegion mr(hr->bottom(), hr->end()); 3893 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3894 } 3895 3896 // Clear the card counts for this region. 3897 // Note: we only need to do this if the region is not young 3898 // (since we don't refine cards in young regions). 3899 if (!skip_hot_card_cache && !hr->is_young()) { 3900 _hot_card_cache->reset_card_counts(hr); 3901 } 3902 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3903 _policy->remset_tracker()->update_at_free(hr); 3904 free_list->add_ordered(hr); 3905 } 3906 3907 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3908 FreeRegionList* free_list) { 3909 assert(hr->is_humongous(), "this is only for humongous regions"); 3910 assert(free_list != NULL, "pre-condition"); 3911 hr->clear_humongous(); 3912 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3913 } 3914 3915 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3916 const uint humongous_regions_removed) { 3917 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3918 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3919 _old_set.bulk_remove(old_regions_removed); 3920 _humongous_set.bulk_remove(humongous_regions_removed); 3921 } 3922 3923 } 3924 3925 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3926 assert(list != NULL, "list can't be null"); 3927 if (!list->is_empty()) { 3928 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3929 _hrm->insert_list_into_free_list(list); 3930 } 3931 } 3932 3933 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3934 decrease_used(bytes); 3935 } 3936 3937 class G1FreeCollectionSetTask : public AbstractGangTask { 3938 private: 3939 3940 // Closure applied to all regions in the collection set to do work that needs to 3941 // be done serially in a single thread. 3942 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3943 private: 3944 G1EvacuationInfo* _evacuation_info; 3945 const size_t* _surviving_young_words; 3946 3947 // Bytes used in successfully evacuated regions before the evacuation. 3948 size_t _before_used_bytes; 3949 // Bytes used in unsucessfully evacuated regions before the evacuation 3950 size_t _after_used_bytes; 3951 3952 size_t _bytes_allocated_in_old_since_last_gc; 3953 3954 size_t _failure_used_words; 3955 size_t _failure_waste_words; 3956 3957 FreeRegionList _local_free_list; 3958 public: 3959 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3960 HeapRegionClosure(), 3961 _evacuation_info(evacuation_info), 3962 _surviving_young_words(surviving_young_words), 3963 _before_used_bytes(0), 3964 _after_used_bytes(0), 3965 _bytes_allocated_in_old_since_last_gc(0), 3966 _failure_used_words(0), 3967 _failure_waste_words(0), 3968 _local_free_list("Local Region List for CSet Freeing") { 3969 } 3970 3971 virtual bool do_heap_region(HeapRegion* r) { 3972 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3973 3974 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3975 g1h->clear_region_attr(r); 3976 3977 if (r->is_young()) { 3978 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(), 3979 "Young index %u is wrong for region %u of type %s with %u young regions", 3980 r->young_index_in_cset(), 3981 r->hrm_index(), 3982 r->get_type_str(), 3983 g1h->collection_set()->young_region_length()); 3984 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 3985 r->record_surv_words_in_group(words_survived); 3986 } 3987 3988 if (!r->evacuation_failed()) { 3989 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 3990 _before_used_bytes += r->used(); 3991 g1h->free_region(r, 3992 &_local_free_list, 3993 true, /* skip_remset */ 3994 true, /* skip_hot_card_cache */ 3995 true /* locked */); 3996 } else { 3997 r->uninstall_surv_rate_group(); 3998 r->clear_young_index_in_cset(); 3999 r->set_evacuation_failed(false); 4000 // When moving a young gen region to old gen, we "allocate" that whole region 4001 // there. This is in addition to any already evacuated objects. Notify the 4002 // policy about that. 4003 // Old gen regions do not cause an additional allocation: both the objects 4004 // still in the region and the ones already moved are accounted for elsewhere. 4005 if (r->is_young()) { 4006 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4007 } 4008 // The region is now considered to be old. 4009 r->set_old(); 4010 // Do some allocation statistics accounting. Regions that failed evacuation 4011 // are always made old, so there is no need to update anything in the young 4012 // gen statistics, but we need to update old gen statistics. 4013 size_t used_words = r->marked_bytes() / HeapWordSize; 4014 4015 _failure_used_words += used_words; 4016 _failure_waste_words += HeapRegion::GrainWords - used_words; 4017 4018 g1h->old_set_add(r); 4019 _after_used_bytes += r->used(); 4020 } 4021 return false; 4022 } 4023 4024 void complete_work() { 4025 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4026 4027 _evacuation_info->set_regions_freed(_local_free_list.length()); 4028 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4029 4030 g1h->prepend_to_freelist(&_local_free_list); 4031 g1h->decrement_summary_bytes(_before_used_bytes); 4032 4033 G1Policy* policy = g1h->policy(); 4034 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4035 4036 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4037 } 4038 }; 4039 4040 G1CollectionSet* _collection_set; 4041 G1SerialFreeCollectionSetClosure _cl; 4042 const size_t* _surviving_young_words; 4043 4044 size_t _rs_length; 4045 4046 volatile jint _serial_work_claim; 4047 4048 struct WorkItem { 4049 uint region_idx; 4050 bool is_young; 4051 bool evacuation_failed; 4052 4053 WorkItem(HeapRegion* r) { 4054 region_idx = r->hrm_index(); 4055 is_young = r->is_young(); 4056 evacuation_failed = r->evacuation_failed(); 4057 } 4058 }; 4059 4060 volatile size_t _parallel_work_claim; 4061 size_t _num_work_items; 4062 WorkItem* _work_items; 4063 4064 void do_serial_work() { 4065 // Need to grab the lock to be allowed to modify the old region list. 4066 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4067 _collection_set->iterate(&_cl); 4068 } 4069 4070 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4071 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4072 4073 HeapRegion* r = g1h->region_at(region_idx); 4074 assert(!g1h->is_on_master_free_list(r), "sanity"); 4075 4076 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length); 4077 4078 if (!is_young) { 4079 g1h->_hot_card_cache->reset_card_counts(r); 4080 } 4081 4082 if (!evacuation_failed) { 4083 r->rem_set()->clear_locked(); 4084 } 4085 } 4086 4087 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4088 private: 4089 size_t _cur_idx; 4090 WorkItem* _work_items; 4091 public: 4092 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4093 4094 virtual bool do_heap_region(HeapRegion* r) { 4095 _work_items[_cur_idx++] = WorkItem(r); 4096 return false; 4097 } 4098 }; 4099 4100 void prepare_work() { 4101 G1PrepareFreeCollectionSetClosure cl(_work_items); 4102 _collection_set->iterate(&cl); 4103 } 4104 4105 void complete_work() { 4106 _cl.complete_work(); 4107 4108 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4109 policy->record_max_rs_length(_rs_length); 4110 policy->cset_regions_freed(); 4111 } 4112 public: 4113 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4114 AbstractGangTask("G1 Free Collection Set"), 4115 _collection_set(collection_set), 4116 _cl(evacuation_info, surviving_young_words), 4117 _surviving_young_words(surviving_young_words), 4118 _rs_length(0), 4119 _serial_work_claim(0), 4120 _parallel_work_claim(0), 4121 _num_work_items(collection_set->region_length()), 4122 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4123 prepare_work(); 4124 } 4125 4126 ~G1FreeCollectionSetTask() { 4127 complete_work(); 4128 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4129 } 4130 4131 // Chunk size for work distribution. The chosen value has been determined experimentally 4132 // to be a good tradeoff between overhead and achievable parallelism. 4133 static uint chunk_size() { return 32; } 4134 4135 virtual void work(uint worker_id) { 4136 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4137 4138 // Claim serial work. 4139 if (_serial_work_claim == 0) { 4140 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4141 if (value == 0) { 4142 double serial_time = os::elapsedTime(); 4143 do_serial_work(); 4144 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4145 } 4146 } 4147 4148 // Start parallel work. 4149 double young_time = 0.0; 4150 bool has_young_time = false; 4151 double non_young_time = 0.0; 4152 bool has_non_young_time = false; 4153 4154 while (true) { 4155 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4156 size_t cur = end - chunk_size(); 4157 4158 if (cur >= _num_work_items) { 4159 break; 4160 } 4161 4162 EventGCPhaseParallel event; 4163 double start_time = os::elapsedTime(); 4164 4165 end = MIN2(end, _num_work_items); 4166 4167 for (; cur < end; cur++) { 4168 bool is_young = _work_items[cur].is_young; 4169 4170 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4171 4172 double end_time = os::elapsedTime(); 4173 double time_taken = end_time - start_time; 4174 if (is_young) { 4175 young_time += time_taken; 4176 has_young_time = true; 4177 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4178 } else { 4179 non_young_time += time_taken; 4180 has_non_young_time = true; 4181 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4182 } 4183 start_time = end_time; 4184 } 4185 } 4186 4187 if (has_young_time) { 4188 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4189 } 4190 if (has_non_young_time) { 4191 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4192 } 4193 } 4194 }; 4195 4196 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4197 _eden.clear(); 4198 4199 double free_cset_start_time = os::elapsedTime(); 4200 4201 { 4202 uint const num_regions = _collection_set.region_length(); 4203 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4204 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4205 4206 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4207 4208 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4209 cl.name(), num_workers, num_regions); 4210 workers()->run_task(&cl, num_workers); 4211 } 4212 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4213 4214 collection_set->clear(); 4215 } 4216 4217 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4218 private: 4219 FreeRegionList* _free_region_list; 4220 HeapRegionSet* _proxy_set; 4221 uint _humongous_objects_reclaimed; 4222 uint _humongous_regions_reclaimed; 4223 size_t _freed_bytes; 4224 public: 4225 4226 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4227 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4228 } 4229 4230 virtual bool do_heap_region(HeapRegion* r) { 4231 if (!r->is_starts_humongous()) { 4232 return false; 4233 } 4234 4235 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4236 4237 oop obj = (oop)r->bottom(); 4238 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4239 4240 // The following checks whether the humongous object is live are sufficient. 4241 // The main additional check (in addition to having a reference from the roots 4242 // or the young gen) is whether the humongous object has a remembered set entry. 4243 // 4244 // A humongous object cannot be live if there is no remembered set for it 4245 // because: 4246 // - there can be no references from within humongous starts regions referencing 4247 // the object because we never allocate other objects into them. 4248 // (I.e. there are no intra-region references that may be missed by the 4249 // remembered set) 4250 // - as soon there is a remembered set entry to the humongous starts region 4251 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4252 // until the end of a concurrent mark. 4253 // 4254 // It is not required to check whether the object has been found dead by marking 4255 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4256 // all objects allocated during that time are considered live. 4257 // SATB marking is even more conservative than the remembered set. 4258 // So if at this point in the collection there is no remembered set entry, 4259 // nobody has a reference to it. 4260 // At the start of collection we flush all refinement logs, and remembered sets 4261 // are completely up-to-date wrt to references to the humongous object. 4262 // 4263 // Other implementation considerations: 4264 // - never consider object arrays at this time because they would pose 4265 // considerable effort for cleaning up the the remembered sets. This is 4266 // required because stale remembered sets might reference locations that 4267 // are currently allocated into. 4268 uint region_idx = r->hrm_index(); 4269 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4270 !r->rem_set()->is_empty()) { 4271 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", 4272 region_idx, 4273 (size_t)obj->size() * HeapWordSize, 4274 p2i(r->bottom()), 4275 r->rem_set()->occupied(), 4276 r->rem_set()->strong_code_roots_list_length(), 4277 next_bitmap->is_marked(r->bottom()), 4278 g1h->is_humongous_reclaim_candidate(region_idx), 4279 obj->is_typeArray() 4280 ); 4281 return false; 4282 } 4283 4284 guarantee(obj->is_typeArray(), 4285 "Only eagerly reclaiming type arrays is supported, but the object " 4286 PTR_FORMAT " is not.", p2i(r->bottom())); 4287 4288 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", 4289 region_idx, 4290 (size_t)obj->size() * HeapWordSize, 4291 p2i(r->bottom()), 4292 r->rem_set()->occupied(), 4293 r->rem_set()->strong_code_roots_list_length(), 4294 next_bitmap->is_marked(r->bottom()), 4295 g1h->is_humongous_reclaim_candidate(region_idx), 4296 obj->is_typeArray() 4297 ); 4298 4299 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4300 cm->humongous_object_eagerly_reclaimed(r); 4301 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4302 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4303 region_idx, 4304 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4305 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4306 _humongous_objects_reclaimed++; 4307 do { 4308 HeapRegion* next = g1h->next_region_in_humongous(r); 4309 _freed_bytes += r->used(); 4310 r->set_containing_set(NULL); 4311 _humongous_regions_reclaimed++; 4312 g1h->free_humongous_region(r, _free_region_list); 4313 r = next; 4314 } while (r != NULL); 4315 4316 return false; 4317 } 4318 4319 uint humongous_objects_reclaimed() { 4320 return _humongous_objects_reclaimed; 4321 } 4322 4323 uint humongous_regions_reclaimed() { 4324 return _humongous_regions_reclaimed; 4325 } 4326 4327 size_t bytes_freed() const { 4328 return _freed_bytes; 4329 } 4330 }; 4331 4332 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4333 assert_at_safepoint_on_vm_thread(); 4334 4335 if (!G1EagerReclaimHumongousObjects || 4336 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4337 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4338 return; 4339 } 4340 4341 double start_time = os::elapsedTime(); 4342 4343 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4344 4345 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4346 heap_region_iterate(&cl); 4347 4348 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4349 4350 G1HRPrinter* hrp = hr_printer(); 4351 if (hrp->is_active()) { 4352 FreeRegionListIterator iter(&local_cleanup_list); 4353 while (iter.more_available()) { 4354 HeapRegion* hr = iter.get_next(); 4355 hrp->cleanup(hr); 4356 } 4357 } 4358 4359 prepend_to_freelist(&local_cleanup_list); 4360 decrement_summary_bytes(cl.bytes_freed()); 4361 4362 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4363 cl.humongous_objects_reclaimed()); 4364 } 4365 4366 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4367 public: 4368 virtual bool do_heap_region(HeapRegion* r) { 4369 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4370 G1CollectedHeap::heap()->clear_region_attr(r); 4371 r->clear_young_index_in_cset(); 4372 return false; 4373 } 4374 }; 4375 4376 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4377 G1AbandonCollectionSetClosure cl; 4378 collection_set_iterate_all(&cl); 4379 4380 collection_set->clear(); 4381 collection_set->stop_incremental_building(); 4382 } 4383 4384 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4385 return _allocator->is_retained_old_region(hr); 4386 } 4387 4388 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4389 _eden.add(hr); 4390 _policy->set_region_eden(hr); 4391 } 4392 4393 #ifdef ASSERT 4394 4395 class NoYoungRegionsClosure: public HeapRegionClosure { 4396 private: 4397 bool _success; 4398 public: 4399 NoYoungRegionsClosure() : _success(true) { } 4400 bool do_heap_region(HeapRegion* r) { 4401 if (r->is_young()) { 4402 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4403 p2i(r->bottom()), p2i(r->end())); 4404 _success = false; 4405 } 4406 return false; 4407 } 4408 bool success() { return _success; } 4409 }; 4410 4411 bool G1CollectedHeap::check_young_list_empty() { 4412 bool ret = (young_regions_count() == 0); 4413 4414 NoYoungRegionsClosure closure; 4415 heap_region_iterate(&closure); 4416 ret = ret && closure.success(); 4417 4418 return ret; 4419 } 4420 4421 #endif // ASSERT 4422 4423 class TearDownRegionSetsClosure : public HeapRegionClosure { 4424 HeapRegionSet *_old_set; 4425 4426 public: 4427 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4428 4429 bool do_heap_region(HeapRegion* r) { 4430 if (r->is_old()) { 4431 _old_set->remove(r); 4432 } else if(r->is_young()) { 4433 r->uninstall_surv_rate_group(); 4434 } else { 4435 // We ignore free regions, we'll empty the free list afterwards. 4436 // We ignore humongous and archive regions, we're not tearing down these 4437 // sets. 4438 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4439 "it cannot be another type"); 4440 } 4441 return false; 4442 } 4443 4444 ~TearDownRegionSetsClosure() { 4445 assert(_old_set->is_empty(), "post-condition"); 4446 } 4447 }; 4448 4449 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4450 assert_at_safepoint_on_vm_thread(); 4451 4452 if (!free_list_only) { 4453 TearDownRegionSetsClosure cl(&_old_set); 4454 heap_region_iterate(&cl); 4455 4456 // Note that emptying the _young_list is postponed and instead done as 4457 // the first step when rebuilding the regions sets again. The reason for 4458 // this is that during a full GC string deduplication needs to know if 4459 // a collected region was young or old when the full GC was initiated. 4460 } 4461 _hrm->remove_all_free_regions(); 4462 } 4463 4464 void G1CollectedHeap::increase_used(size_t bytes) { 4465 _summary_bytes_used += bytes; 4466 } 4467 4468 void G1CollectedHeap::decrease_used(size_t bytes) { 4469 assert(_summary_bytes_used >= bytes, 4470 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4471 _summary_bytes_used, bytes); 4472 _summary_bytes_used -= bytes; 4473 } 4474 4475 void G1CollectedHeap::set_used(size_t bytes) { 4476 _summary_bytes_used = bytes; 4477 } 4478 4479 class RebuildRegionSetsClosure : public HeapRegionClosure { 4480 private: 4481 bool _free_list_only; 4482 4483 HeapRegionSet* _old_set; 4484 HeapRegionManager* _hrm; 4485 4486 size_t _total_used; 4487 4488 public: 4489 RebuildRegionSetsClosure(bool free_list_only, 4490 HeapRegionSet* old_set, 4491 HeapRegionManager* hrm) : 4492 _free_list_only(free_list_only), 4493 _old_set(old_set), _hrm(hrm), _total_used(0) { 4494 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4495 if (!free_list_only) { 4496 assert(_old_set->is_empty(), "pre-condition"); 4497 } 4498 } 4499 4500 bool do_heap_region(HeapRegion* r) { 4501 if (r->is_empty()) { 4502 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4503 // Add free regions to the free list 4504 r->set_free(); 4505 _hrm->insert_into_free_list(r); 4506 } else if (!_free_list_only) { 4507 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4508 4509 if (r->is_archive() || r->is_humongous()) { 4510 // We ignore archive and humongous regions. We left these sets unchanged. 4511 } else { 4512 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4513 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4514 r->move_to_old(); 4515 _old_set->add(r); 4516 } 4517 _total_used += r->used(); 4518 } 4519 4520 return false; 4521 } 4522 4523 size_t total_used() { 4524 return _total_used; 4525 } 4526 }; 4527 4528 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4529 assert_at_safepoint_on_vm_thread(); 4530 4531 if (!free_list_only) { 4532 _eden.clear(); 4533 _survivor.clear(); 4534 } 4535 4536 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4537 heap_region_iterate(&cl); 4538 4539 if (!free_list_only) { 4540 set_used(cl.total_used()); 4541 if (_archive_allocator != NULL) { 4542 _archive_allocator->clear_used(); 4543 } 4544 } 4545 assert_used_and_recalculate_used_equal(this); 4546 } 4547 4548 // Methods for the mutator alloc region 4549 4550 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4551 bool force) { 4552 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4553 bool should_allocate = policy()->should_allocate_mutator_region(); 4554 if (force || should_allocate) { 4555 HeapRegion* new_alloc_region = new_region(word_size, 4556 HeapRegionType::Eden, 4557 false /* do_expand */); 4558 if (new_alloc_region != NULL) { 4559 set_region_short_lived_locked(new_alloc_region); 4560 _hr_printer.alloc(new_alloc_region, !should_allocate); 4561 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4562 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4563 return new_alloc_region; 4564 } 4565 } 4566 return NULL; 4567 } 4568 4569 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4570 size_t allocated_bytes) { 4571 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4572 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4573 4574 collection_set()->add_eden_region(alloc_region); 4575 increase_used(allocated_bytes); 4576 _eden.add_used_bytes(allocated_bytes); 4577 _hr_printer.retire(alloc_region); 4578 4579 // We update the eden sizes here, when the region is retired, 4580 // instead of when it's allocated, since this is the point that its 4581 // used space has been recorded in _summary_bytes_used. 4582 g1mm()->update_eden_size(); 4583 } 4584 4585 // Methods for the GC alloc regions 4586 4587 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4588 if (dest.is_old()) { 4589 return true; 4590 } else { 4591 return survivor_regions_count() < policy()->max_survivor_regions(); 4592 } 4593 } 4594 4595 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) { 4596 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4597 4598 if (!has_more_regions(dest)) { 4599 return NULL; 4600 } 4601 4602 HeapRegionType type; 4603 if (dest.is_young()) { 4604 type = HeapRegionType::Survivor; 4605 } else { 4606 type = HeapRegionType::Old; 4607 } 4608 4609 HeapRegion* new_alloc_region = new_region(word_size, 4610 type, 4611 true /* do_expand */); 4612 4613 if (new_alloc_region != NULL) { 4614 if (type.is_survivor()) { 4615 new_alloc_region->set_survivor(); 4616 _survivor.add(new_alloc_region); 4617 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4618 } else { 4619 new_alloc_region->set_old(); 4620 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4621 } 4622 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4623 register_region_with_region_attr(new_alloc_region); 4624 _hr_printer.alloc(new_alloc_region); 4625 return new_alloc_region; 4626 } 4627 return NULL; 4628 } 4629 4630 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4631 size_t allocated_bytes, 4632 G1HeapRegionAttr dest) { 4633 policy()->record_bytes_copied_during_gc(allocated_bytes); 4634 if (dest.is_old()) { 4635 old_set_add(alloc_region); 4636 } else { 4637 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4638 _survivor.add_used_bytes(allocated_bytes); 4639 } 4640 4641 bool const during_im = collector_state()->in_initial_mark_gc(); 4642 if (during_im && allocated_bytes > 0) { 4643 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4644 } 4645 _hr_printer.retire(alloc_region); 4646 } 4647 4648 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4649 bool expanded = false; 4650 uint index = _hrm->find_highest_free(&expanded); 4651 4652 if (index != G1_NO_HRM_INDEX) { 4653 if (expanded) { 4654 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4655 HeapRegion::GrainWords * HeapWordSize); 4656 } 4657 _hrm->allocate_free_regions_starting_at(index, 1); 4658 return region_at(index); 4659 } 4660 return NULL; 4661 } 4662 4663 // Optimized nmethod scanning 4664 4665 class RegisterNMethodOopClosure: public OopClosure { 4666 G1CollectedHeap* _g1h; 4667 nmethod* _nm; 4668 4669 template <class T> void do_oop_work(T* p) { 4670 T heap_oop = RawAccess<>::oop_load(p); 4671 if (!CompressedOops::is_null(heap_oop)) { 4672 oop obj = CompressedOops::decode_not_null(heap_oop); 4673 HeapRegion* hr = _g1h->heap_region_containing(obj); 4674 assert(!hr->is_continues_humongous(), 4675 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4676 " starting at " HR_FORMAT, 4677 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4678 4679 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4680 hr->add_strong_code_root_locked(_nm); 4681 } 4682 } 4683 4684 public: 4685 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4686 _g1h(g1h), _nm(nm) {} 4687 4688 void do_oop(oop* p) { do_oop_work(p); } 4689 void do_oop(narrowOop* p) { do_oop_work(p); } 4690 }; 4691 4692 class UnregisterNMethodOopClosure: public OopClosure { 4693 G1CollectedHeap* _g1h; 4694 nmethod* _nm; 4695 4696 template <class T> void do_oop_work(T* p) { 4697 T heap_oop = RawAccess<>::oop_load(p); 4698 if (!CompressedOops::is_null(heap_oop)) { 4699 oop obj = CompressedOops::decode_not_null(heap_oop); 4700 HeapRegion* hr = _g1h->heap_region_containing(obj); 4701 assert(!hr->is_continues_humongous(), 4702 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4703 " starting at " HR_FORMAT, 4704 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4705 4706 hr->remove_strong_code_root(_nm); 4707 } 4708 } 4709 4710 public: 4711 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4712 _g1h(g1h), _nm(nm) {} 4713 4714 void do_oop(oop* p) { do_oop_work(p); } 4715 void do_oop(narrowOop* p) { do_oop_work(p); } 4716 }; 4717 4718 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4719 guarantee(nm != NULL, "sanity"); 4720 RegisterNMethodOopClosure reg_cl(this, nm); 4721 nm->oops_do(®_cl); 4722 } 4723 4724 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4725 guarantee(nm != NULL, "sanity"); 4726 UnregisterNMethodOopClosure reg_cl(this, nm); 4727 nm->oops_do(®_cl, true); 4728 } 4729 4730 void G1CollectedHeap::purge_code_root_memory() { 4731 double purge_start = os::elapsedTime(); 4732 G1CodeRootSet::purge(); 4733 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4734 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4735 } 4736 4737 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4738 G1CollectedHeap* _g1h; 4739 4740 public: 4741 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4742 _g1h(g1h) {} 4743 4744 void do_code_blob(CodeBlob* cb) { 4745 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4746 if (nm == NULL) { 4747 return; 4748 } 4749 4750 _g1h->register_nmethod(nm); 4751 } 4752 }; 4753 4754 void G1CollectedHeap::rebuild_strong_code_roots() { 4755 RebuildStrongCodeRootClosure blob_cl(this); 4756 CodeCache::blobs_do(&blob_cl); 4757 } 4758 4759 void G1CollectedHeap::initialize_serviceability() { 4760 _g1mm->initialize_serviceability(); 4761 } 4762 4763 MemoryUsage G1CollectedHeap::memory_usage() { 4764 return _g1mm->memory_usage(); 4765 } 4766 4767 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4768 return _g1mm->memory_managers(); 4769 } 4770 4771 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4772 return _g1mm->memory_pools(); 4773 }