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/g1CollectedHeap.inline.hpp" 35 #include "gc/g1/g1CollectionSet.hpp" 36 #include "gc/g1/g1CollectorState.hpp" 37 #include "gc/g1/g1ConcurrentRefine.hpp" 38 #include "gc/g1/g1ConcurrentRefineThread.hpp" 39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 40 #include "gc/g1/g1DirtyCardQueue.hpp" 41 #include "gc/g1/g1EvacStats.inline.hpp" 42 #include "gc/g1/g1FullCollector.hpp" 43 #include "gc/g1/g1GCPhaseTimes.hpp" 44 #include "gc/g1/g1HeapSizingPolicy.hpp" 45 #include "gc/g1/g1HeapTransition.hpp" 46 #include "gc/g1/g1HeapVerifier.hpp" 47 #include "gc/g1/g1HotCardCache.hpp" 48 #include "gc/g1/g1MemoryPool.hpp" 49 #include "gc/g1/g1OopClosures.inline.hpp" 50 #include "gc/g1/g1ParScanThreadState.inline.hpp" 51 #include "gc/g1/g1Policy.hpp" 52 #include "gc/g1/g1RegionToSpaceMapper.hpp" 53 #include "gc/g1/g1RemSet.hpp" 54 #include "gc/g1/g1RootClosures.hpp" 55 #include "gc/g1/g1RootProcessor.hpp" 56 #include "gc/g1/g1SATBMarkQueueSet.hpp" 57 #include "gc/g1/g1StringDedup.hpp" 58 #include "gc/g1/g1ThreadLocalData.hpp" 59 #include "gc/g1/g1YCTypes.hpp" 60 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 61 #include "gc/g1/g1VMOperations.hpp" 62 #include "gc/g1/heapRegion.inline.hpp" 63 #include "gc/g1/heapRegionRemSet.hpp" 64 #include "gc/g1/heapRegionSet.inline.hpp" 65 #include "gc/shared/gcBehaviours.hpp" 66 #include "gc/shared/gcHeapSummary.hpp" 67 #include "gc/shared/gcId.hpp" 68 #include "gc/shared/gcLocker.hpp" 69 #include "gc/shared/gcTimer.hpp" 70 #include "gc/shared/gcTrace.hpp" 71 #include "gc/shared/gcTraceTime.inline.hpp" 72 #include "gc/shared/generationSpec.hpp" 73 #include "gc/shared/isGCActiveMark.hpp" 74 #include "gc/shared/oopStorageParState.hpp" 75 #include "gc/shared/parallelCleaning.hpp" 76 #include "gc/shared/preservedMarks.inline.hpp" 77 #include "gc/shared/suspendibleThreadSet.hpp" 78 #include "gc/shared/referenceProcessor.inline.hpp" 79 #include "gc/shared/taskqueue.inline.hpp" 80 #include "gc/shared/weakProcessor.inline.hpp" 81 #include "gc/shared/workerPolicy.hpp" 82 #include "logging/log.hpp" 83 #include "memory/allocation.hpp" 84 #include "memory/iterator.hpp" 85 #include "memory/resourceArea.hpp" 86 #include "memory/universe.hpp" 87 #include "oops/access.inline.hpp" 88 #include "oops/compressedOops.inline.hpp" 89 #include "oops/oop.inline.hpp" 90 #include "runtime/atomic.hpp" 91 #include "runtime/flags/flagSetting.hpp" 92 #include "runtime/handles.inline.hpp" 93 #include "runtime/init.hpp" 94 #include "runtime/orderAccess.hpp" 95 #include "runtime/threadSMR.hpp" 96 #include "runtime/vmThread.hpp" 97 #include "utilities/align.hpp" 98 #include "utilities/globalDefinitions.hpp" 99 #include "utilities/stack.inline.hpp" 100 101 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 102 103 // INVARIANTS/NOTES 104 // 105 // All allocation activity covered by the G1CollectedHeap interface is 106 // serialized by acquiring the HeapLock. This happens in mem_allocate 107 // and allocate_new_tlab, which are the "entry" points to the 108 // allocation code from the rest of the JVM. (Note that this does not 109 // apply to TLAB allocation, which is not part of this interface: it 110 // is done by clients of this interface.) 111 112 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 113 private: 114 size_t _num_dirtied; 115 G1CollectedHeap* _g1h; 116 G1CardTable* _g1_ct; 117 118 HeapRegion* region_for_card(CardValue* card_ptr) const { 119 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 120 } 121 122 bool will_become_free(HeapRegion* hr) const { 123 // A region will be freed by free_collection_set if the region is in the 124 // collection set and has not had an evacuation failure. 125 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 126 } 127 128 public: 129 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 130 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 131 132 bool do_card_ptr(CardValue* card_ptr, uint worker_i) { 133 HeapRegion* hr = region_for_card(card_ptr); 134 135 // Should only dirty cards in regions that won't be freed. 136 if (!will_become_free(hr)) { 137 *card_ptr = G1CardTable::dirty_card_val(); 138 _num_dirtied++; 139 } 140 141 return true; 142 } 143 144 size_t num_dirtied() const { return _num_dirtied; } 145 }; 146 147 148 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 149 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 150 } 151 152 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 153 // The from card cache is not the memory that is actually committed. So we cannot 154 // take advantage of the zero_filled parameter. 155 reset_from_card_cache(start_idx, num_regions); 156 } 157 158 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 159 Ticks start = Ticks::now(); 160 workers()->run_task(task, workers()->active_workers()); 161 return Ticks::now() - start; 162 } 163 164 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 165 MemRegion mr) { 166 return new HeapRegion(hrs_index, bot(), mr); 167 } 168 169 // Private methods. 170 171 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) { 172 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 173 "the only time we use this to allocate a humongous region is " 174 "when we are allocating a single humongous region"); 175 176 HeapRegion* res = _hrm->allocate_free_region(type); 177 178 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 179 // Currently, only attempts to allocate GC alloc regions set 180 // do_expand to true. So, we should only reach here during a 181 // safepoint. If this assumption changes we might have to 182 // reconsider the use of _expand_heap_after_alloc_failure. 183 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 184 185 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 186 word_size * HeapWordSize); 187 188 if (expand(word_size * HeapWordSize)) { 189 // Given that expand() succeeded in expanding the heap, and we 190 // always expand the heap by an amount aligned to the heap 191 // region size, the free list should in theory not be empty. 192 // In either case allocate_free_region() will check for NULL. 193 res = _hrm->allocate_free_region(type); 194 } else { 195 _expand_heap_after_alloc_failure = false; 196 } 197 } 198 return res; 199 } 200 201 HeapWord* 202 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 203 uint num_regions, 204 size_t word_size) { 205 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 206 assert(is_humongous(word_size), "word_size should be humongous"); 207 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 208 209 // Index of last region in the series. 210 uint last = first + num_regions - 1; 211 212 // We need to initialize the region(s) we just discovered. This is 213 // a bit tricky given that it can happen concurrently with 214 // refinement threads refining cards on these regions and 215 // potentially wanting to refine the BOT as they are scanning 216 // those cards (this can happen shortly after a cleanup; see CR 217 // 6991377). So we have to set up the region(s) carefully and in 218 // a specific order. 219 220 // The word size sum of all the regions we will allocate. 221 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 222 assert(word_size <= word_size_sum, "sanity"); 223 224 // This will be the "starts humongous" region. 225 HeapRegion* first_hr = region_at(first); 226 // The header of the new object will be placed at the bottom of 227 // the first region. 228 HeapWord* new_obj = first_hr->bottom(); 229 // This will be the new top of the new object. 230 HeapWord* obj_top = new_obj + word_size; 231 232 // First, we need to zero the header of the space that we will be 233 // allocating. When we update top further down, some refinement 234 // threads might try to scan the region. By zeroing the header we 235 // ensure that any thread that will try to scan the region will 236 // come across the zero klass word and bail out. 237 // 238 // NOTE: It would not have been correct to have used 239 // CollectedHeap::fill_with_object() and make the space look like 240 // an int array. The thread that is doing the allocation will 241 // later update the object header to a potentially different array 242 // type and, for a very short period of time, the klass and length 243 // fields will be inconsistent. This could cause a refinement 244 // thread to calculate the object size incorrectly. 245 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 246 247 // Next, pad out the unused tail of the last region with filler 248 // objects, for improved usage accounting. 249 // How many words we use for filler objects. 250 size_t word_fill_size = word_size_sum - word_size; 251 252 // How many words memory we "waste" which cannot hold a filler object. 253 size_t words_not_fillable = 0; 254 255 if (word_fill_size >= min_fill_size()) { 256 fill_with_objects(obj_top, word_fill_size); 257 } else if (word_fill_size > 0) { 258 // We have space to fill, but we cannot fit an object there. 259 words_not_fillable = word_fill_size; 260 word_fill_size = 0; 261 } 262 263 // We will set up the first region as "starts humongous". This 264 // will also update the BOT covering all the regions to reflect 265 // that there is a single object that starts at the bottom of the 266 // first region. 267 first_hr->set_starts_humongous(obj_top, word_fill_size); 268 _policy->remset_tracker()->update_at_allocate(first_hr); 269 // Then, if there are any, we will set up the "continues 270 // humongous" regions. 271 HeapRegion* hr = NULL; 272 for (uint i = first + 1; i <= last; ++i) { 273 hr = region_at(i); 274 hr->set_continues_humongous(first_hr); 275 _policy->remset_tracker()->update_at_allocate(hr); 276 } 277 278 // Up to this point no concurrent thread would have been able to 279 // do any scanning on any region in this series. All the top 280 // fields still point to bottom, so the intersection between 281 // [bottom,top] and [card_start,card_end] will be empty. Before we 282 // update the top fields, we'll do a storestore to make sure that 283 // no thread sees the update to top before the zeroing of the 284 // object header and the BOT initialization. 285 OrderAccess::storestore(); 286 287 // Now, we will update the top fields of the "continues humongous" 288 // regions except the last one. 289 for (uint i = first; i < last; ++i) { 290 hr = region_at(i); 291 hr->set_top(hr->end()); 292 } 293 294 hr = region_at(last); 295 // If we cannot fit a filler object, we must set top to the end 296 // of the humongous object, otherwise we cannot iterate the heap 297 // and the BOT will not be complete. 298 hr->set_top(hr->end() - words_not_fillable); 299 300 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 301 "obj_top should be in last region"); 302 303 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 304 305 assert(words_not_fillable == 0 || 306 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 307 "Miscalculation in humongous allocation"); 308 309 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 310 311 for (uint i = first; i <= last; ++i) { 312 hr = region_at(i); 313 _humongous_set.add(hr); 314 _hr_printer.alloc(hr); 315 } 316 317 return new_obj; 318 } 319 320 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 321 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 322 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 323 } 324 325 // If could fit into free regions w/o expansion, try. 326 // Otherwise, if can expand, do so. 327 // Otherwise, if using ex regions might help, try with ex given back. 328 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 329 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 330 331 _verifier->verify_region_sets_optional(); 332 333 uint first = G1_NO_HRM_INDEX; 334 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 335 336 if (obj_regions == 1) { 337 // Only one region to allocate, try to use a fast path by directly allocating 338 // from the free lists. Do not try to expand here, we will potentially do that 339 // later. 340 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 341 if (hr != NULL) { 342 first = hr->hrm_index(); 343 } 344 } else { 345 // Policy: Try only empty regions (i.e. already committed first). Maybe we 346 // are lucky enough to find some. 347 first = _hrm->find_contiguous_only_empty(obj_regions); 348 if (first != G1_NO_HRM_INDEX) { 349 _hrm->allocate_free_regions_starting_at(first, obj_regions); 350 } 351 } 352 353 if (first == G1_NO_HRM_INDEX) { 354 // Policy: We could not find enough regions for the humongous object in the 355 // free list. Look through the heap to find a mix of free and uncommitted regions. 356 // If so, try expansion. 357 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 358 if (first != G1_NO_HRM_INDEX) { 359 // We found something. Make sure these regions are committed, i.e. expand 360 // the heap. Alternatively we could do a defragmentation GC. 361 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 362 word_size * HeapWordSize); 363 364 _hrm->expand_at(first, obj_regions, workers()); 365 policy()->record_new_heap_size(num_regions()); 366 367 #ifdef ASSERT 368 for (uint i = first; i < first + obj_regions; ++i) { 369 HeapRegion* hr = region_at(i); 370 assert(hr->is_free(), "sanity"); 371 assert(hr->is_empty(), "sanity"); 372 assert(is_on_master_free_list(hr), "sanity"); 373 } 374 #endif 375 _hrm->allocate_free_regions_starting_at(first, obj_regions); 376 } else { 377 // Policy: Potentially trigger a defragmentation GC. 378 } 379 } 380 381 HeapWord* result = NULL; 382 if (first != G1_NO_HRM_INDEX) { 383 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 384 assert(result != NULL, "it should always return a valid result"); 385 386 // A successful humongous object allocation changes the used space 387 // information of the old generation so we need to recalculate the 388 // sizes and update the jstat counters here. 389 g1mm()->update_sizes(); 390 } 391 392 _verifier->verify_region_sets_optional(); 393 394 return result; 395 } 396 397 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 398 size_t requested_size, 399 size_t* actual_size) { 400 assert_heap_not_locked_and_not_at_safepoint(); 401 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 402 403 return attempt_allocation(min_size, requested_size, actual_size); 404 } 405 406 HeapWord* 407 G1CollectedHeap::mem_allocate(size_t word_size, 408 bool* gc_overhead_limit_was_exceeded) { 409 assert_heap_not_locked_and_not_at_safepoint(); 410 411 if (is_humongous(word_size)) { 412 return attempt_allocation_humongous(word_size); 413 } 414 size_t dummy = 0; 415 return attempt_allocation(word_size, word_size, &dummy); 416 } 417 418 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 419 ResourceMark rm; // For retrieving the thread names in log messages. 420 421 // Make sure you read the note in attempt_allocation_humongous(). 422 423 assert_heap_not_locked_and_not_at_safepoint(); 424 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 425 "be called for humongous allocation requests"); 426 427 // We should only get here after the first-level allocation attempt 428 // (attempt_allocation()) failed to allocate. 429 430 // We will loop until a) we manage to successfully perform the 431 // allocation or b) we successfully schedule a collection which 432 // fails to perform the allocation. b) is the only case when we'll 433 // return NULL. 434 HeapWord* result = NULL; 435 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 436 bool should_try_gc; 437 uint gc_count_before; 438 439 { 440 MutexLocker x(Heap_lock); 441 result = _allocator->attempt_allocation_locked(word_size); 442 if (result != NULL) { 443 return result; 444 } 445 446 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 447 // This is different to when only GCLocker::needs_gc() is set: try to avoid 448 // waiting because the GCLocker is active to not wait too long. 449 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 450 // No need for an ergo message here, can_expand_young_list() does this when 451 // it returns true. 452 result = _allocator->attempt_allocation_force(word_size); 453 if (result != NULL) { 454 return result; 455 } 456 } 457 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 458 // the GCLocker initiated GC has been performed and then retry. This includes 459 // the case when the GC Locker is not active but has not been performed. 460 should_try_gc = !GCLocker::needs_gc(); 461 // Read the GC count while still holding the Heap_lock. 462 gc_count_before = total_collections(); 463 } 464 465 if (should_try_gc) { 466 bool succeeded; 467 result = do_collection_pause(word_size, gc_count_before, &succeeded, 468 GCCause::_g1_inc_collection_pause); 469 if (result != NULL) { 470 assert(succeeded, "only way to get back a non-NULL result"); 471 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 472 Thread::current()->name(), p2i(result)); 473 return result; 474 } 475 476 if (succeeded) { 477 // We successfully scheduled a collection which failed to allocate. No 478 // point in trying to allocate further. We'll just return NULL. 479 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 480 SIZE_FORMAT " words", Thread::current()->name(), word_size); 481 return NULL; 482 } 483 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 484 Thread::current()->name(), word_size); 485 } else { 486 // Failed to schedule a collection. 487 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 488 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 489 SIZE_FORMAT " words", Thread::current()->name(), word_size); 490 return NULL; 491 } 492 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 493 // The GCLocker is either active or the GCLocker initiated 494 // GC has not yet been performed. Stall until it is and 495 // then retry the allocation. 496 GCLocker::stall_until_clear(); 497 gclocker_retry_count += 1; 498 } 499 500 // We can reach here if we were unsuccessful in scheduling a 501 // collection (because another thread beat us to it) or if we were 502 // stalled due to the GC locker. In either can we should retry the 503 // allocation attempt in case another thread successfully 504 // performed a collection and reclaimed enough space. We do the 505 // first attempt (without holding the Heap_lock) here and the 506 // follow-on attempt will be at the start of the next loop 507 // iteration (after taking the Heap_lock). 508 size_t dummy = 0; 509 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 510 if (result != NULL) { 511 return result; 512 } 513 514 // Give a warning if we seem to be looping forever. 515 if ((QueuedAllocationWarningCount > 0) && 516 (try_count % QueuedAllocationWarningCount == 0)) { 517 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 518 Thread::current()->name(), try_count, word_size); 519 } 520 } 521 522 ShouldNotReachHere(); 523 return NULL; 524 } 525 526 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 527 assert_at_safepoint_on_vm_thread(); 528 if (_archive_allocator == NULL) { 529 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 530 } 531 } 532 533 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 534 // Allocations in archive regions cannot be of a size that would be considered 535 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 536 // may be different at archive-restore time. 537 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 538 } 539 540 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 541 assert_at_safepoint_on_vm_thread(); 542 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 543 if (is_archive_alloc_too_large(word_size)) { 544 return NULL; 545 } 546 return _archive_allocator->archive_mem_allocate(word_size); 547 } 548 549 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 550 size_t end_alignment_in_bytes) { 551 assert_at_safepoint_on_vm_thread(); 552 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 553 554 // Call complete_archive to do the real work, filling in the MemRegion 555 // array with the archive regions. 556 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 557 delete _archive_allocator; 558 _archive_allocator = NULL; 559 } 560 561 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 562 assert(ranges != NULL, "MemRegion array NULL"); 563 assert(count != 0, "No MemRegions provided"); 564 MemRegion reserved = _hrm->reserved(); 565 for (size_t i = 0; i < count; i++) { 566 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 567 return false; 568 } 569 } 570 return true; 571 } 572 573 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 574 size_t count, 575 bool open) { 576 assert(!is_init_completed(), "Expect to be called at JVM init time"); 577 assert(ranges != NULL, "MemRegion array NULL"); 578 assert(count != 0, "No MemRegions provided"); 579 MutexLocker x(Heap_lock); 580 581 MemRegion reserved = _hrm->reserved(); 582 HeapWord* prev_last_addr = NULL; 583 HeapRegion* prev_last_region = NULL; 584 585 // Temporarily disable pretouching of heap pages. This interface is used 586 // when mmap'ing archived heap data in, so pre-touching is wasted. 587 FlagSetting fs(AlwaysPreTouch, false); 588 589 // Enable archive object checking used by G1MarkSweep. We have to let it know 590 // about each archive range, so that objects in those ranges aren't marked. 591 G1ArchiveAllocator::enable_archive_object_check(); 592 593 // For each specified MemRegion range, allocate the corresponding G1 594 // regions and mark them as archive regions. We expect the ranges 595 // in ascending starting address order, without overlap. 596 for (size_t i = 0; i < count; i++) { 597 MemRegion curr_range = ranges[i]; 598 HeapWord* start_address = curr_range.start(); 599 size_t word_size = curr_range.word_size(); 600 HeapWord* last_address = curr_range.last(); 601 size_t commits = 0; 602 603 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 604 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 605 p2i(start_address), p2i(last_address)); 606 guarantee(start_address > prev_last_addr, 607 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 608 p2i(start_address), p2i(prev_last_addr)); 609 prev_last_addr = last_address; 610 611 // Check for ranges that start in the same G1 region in which the previous 612 // range ended, and adjust the start address so we don't try to allocate 613 // the same region again. If the current range is entirely within that 614 // region, skip it, just adjusting the recorded top. 615 HeapRegion* start_region = _hrm->addr_to_region(start_address); 616 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 617 start_address = start_region->end(); 618 if (start_address > last_address) { 619 increase_used(word_size * HeapWordSize); 620 start_region->set_top(last_address + 1); 621 continue; 622 } 623 start_region->set_top(start_address); 624 curr_range = MemRegion(start_address, last_address + 1); 625 start_region = _hrm->addr_to_region(start_address); 626 } 627 628 // Perform the actual region allocation, exiting if it fails. 629 // Then note how much new space we have allocated. 630 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 631 return false; 632 } 633 increase_used(word_size * HeapWordSize); 634 if (commits != 0) { 635 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 636 HeapRegion::GrainWords * HeapWordSize * commits); 637 638 } 639 640 // Mark each G1 region touched by the range as archive, add it to 641 // the old set, and set top. 642 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 643 HeapRegion* last_region = _hrm->addr_to_region(last_address); 644 prev_last_region = last_region; 645 646 while (curr_region != NULL) { 647 assert(curr_region->is_empty() && !curr_region->is_pinned(), 648 "Region already in use (index %u)", curr_region->hrm_index()); 649 if (open) { 650 curr_region->set_open_archive(); 651 } else { 652 curr_region->set_closed_archive(); 653 } 654 _hr_printer.alloc(curr_region); 655 _archive_set.add(curr_region); 656 HeapWord* top; 657 HeapRegion* next_region; 658 if (curr_region != last_region) { 659 top = curr_region->end(); 660 next_region = _hrm->next_region_in_heap(curr_region); 661 } else { 662 top = last_address + 1; 663 next_region = NULL; 664 } 665 curr_region->set_top(top); 666 curr_region->set_first_dead(top); 667 curr_region->set_end_of_live(top); 668 curr_region = next_region; 669 } 670 671 // Notify mark-sweep of the archive 672 G1ArchiveAllocator::set_range_archive(curr_range, open); 673 } 674 return true; 675 } 676 677 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 678 assert(!is_init_completed(), "Expect to be called at JVM init time"); 679 assert(ranges != NULL, "MemRegion array NULL"); 680 assert(count != 0, "No MemRegions provided"); 681 MemRegion reserved = _hrm->reserved(); 682 HeapWord *prev_last_addr = NULL; 683 HeapRegion* prev_last_region = NULL; 684 685 // For each MemRegion, create filler objects, if needed, in the G1 regions 686 // that contain the address range. The address range actually within the 687 // MemRegion will not be modified. That is assumed to have been initialized 688 // elsewhere, probably via an mmap of archived heap data. 689 MutexLocker x(Heap_lock); 690 for (size_t i = 0; i < count; i++) { 691 HeapWord* start_address = ranges[i].start(); 692 HeapWord* last_address = ranges[i].last(); 693 694 assert(reserved.contains(start_address) && reserved.contains(last_address), 695 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 696 p2i(start_address), p2i(last_address)); 697 assert(start_address > prev_last_addr, 698 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 699 p2i(start_address), p2i(prev_last_addr)); 700 701 HeapRegion* start_region = _hrm->addr_to_region(start_address); 702 HeapRegion* last_region = _hrm->addr_to_region(last_address); 703 HeapWord* bottom_address = start_region->bottom(); 704 705 // Check for a range beginning in the same region in which the 706 // previous one ended. 707 if (start_region == prev_last_region) { 708 bottom_address = prev_last_addr + 1; 709 } 710 711 // Verify that the regions were all marked as archive regions by 712 // alloc_archive_regions. 713 HeapRegion* curr_region = start_region; 714 while (curr_region != NULL) { 715 guarantee(curr_region->is_archive(), 716 "Expected archive region at index %u", curr_region->hrm_index()); 717 if (curr_region != last_region) { 718 curr_region = _hrm->next_region_in_heap(curr_region); 719 } else { 720 curr_region = NULL; 721 } 722 } 723 724 prev_last_addr = last_address; 725 prev_last_region = last_region; 726 727 // Fill the memory below the allocated range with dummy object(s), 728 // if the region bottom does not match the range start, or if the previous 729 // range ended within the same G1 region, and there is a gap. 730 if (start_address != bottom_address) { 731 size_t fill_size = pointer_delta(start_address, bottom_address); 732 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 733 increase_used(fill_size * HeapWordSize); 734 } 735 } 736 } 737 738 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 739 size_t desired_word_size, 740 size_t* actual_word_size) { 741 assert_heap_not_locked_and_not_at_safepoint(); 742 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 743 "be called for humongous allocation requests"); 744 745 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 746 747 if (result == NULL) { 748 *actual_word_size = desired_word_size; 749 result = attempt_allocation_slow(desired_word_size); 750 } 751 752 assert_heap_not_locked(); 753 if (result != NULL) { 754 assert(*actual_word_size != 0, "Actual size must have been set here"); 755 dirty_young_block(result, *actual_word_size); 756 } else { 757 *actual_word_size = 0; 758 } 759 760 return result; 761 } 762 763 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 764 assert(!is_init_completed(), "Expect to be called at JVM init time"); 765 assert(ranges != NULL, "MemRegion array NULL"); 766 assert(count != 0, "No MemRegions provided"); 767 MemRegion reserved = _hrm->reserved(); 768 HeapWord* prev_last_addr = NULL; 769 HeapRegion* prev_last_region = NULL; 770 size_t size_used = 0; 771 size_t uncommitted_regions = 0; 772 773 // For each Memregion, free the G1 regions that constitute it, and 774 // notify mark-sweep that the range is no longer to be considered 'archive.' 775 MutexLocker x(Heap_lock); 776 for (size_t i = 0; i < count; i++) { 777 HeapWord* start_address = ranges[i].start(); 778 HeapWord* last_address = ranges[i].last(); 779 780 assert(reserved.contains(start_address) && reserved.contains(last_address), 781 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 782 p2i(start_address), p2i(last_address)); 783 assert(start_address > prev_last_addr, 784 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 785 p2i(start_address), p2i(prev_last_addr)); 786 size_used += ranges[i].byte_size(); 787 prev_last_addr = last_address; 788 789 HeapRegion* start_region = _hrm->addr_to_region(start_address); 790 HeapRegion* last_region = _hrm->addr_to_region(last_address); 791 792 // Check for ranges that start in the same G1 region in which the previous 793 // range ended, and adjust the start address so we don't try to free 794 // the same region again. If the current range is entirely within that 795 // region, skip it. 796 if (start_region == prev_last_region) { 797 start_address = start_region->end(); 798 if (start_address > last_address) { 799 continue; 800 } 801 start_region = _hrm->addr_to_region(start_address); 802 } 803 prev_last_region = last_region; 804 805 // After verifying that each region was marked as an archive region by 806 // alloc_archive_regions, set it free and empty and uncommit it. 807 HeapRegion* curr_region = start_region; 808 while (curr_region != NULL) { 809 guarantee(curr_region->is_archive(), 810 "Expected archive region at index %u", curr_region->hrm_index()); 811 uint curr_index = curr_region->hrm_index(); 812 _archive_set.remove(curr_region); 813 curr_region->set_free(); 814 curr_region->set_top(curr_region->bottom()); 815 if (curr_region != last_region) { 816 curr_region = _hrm->next_region_in_heap(curr_region); 817 } else { 818 curr_region = NULL; 819 } 820 _hrm->shrink_at(curr_index, 1); 821 uncommitted_regions++; 822 } 823 824 // Notify mark-sweep that this is no longer an archive range. 825 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 826 } 827 828 if (uncommitted_regions != 0) { 829 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 830 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 831 } 832 decrease_used(size_used); 833 } 834 835 oop G1CollectedHeap::materialize_archived_object(oop obj) { 836 assert(obj != NULL, "archived obj is NULL"); 837 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 838 839 // Loading an archived object makes it strongly reachable. If it is 840 // loaded during concurrent marking, it must be enqueued to the SATB 841 // queue, shading the previously white object gray. 842 G1BarrierSet::enqueue(obj); 843 844 return obj; 845 } 846 847 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 848 ResourceMark rm; // For retrieving the thread names in log messages. 849 850 // The structure of this method has a lot of similarities to 851 // attempt_allocation_slow(). The reason these two were not merged 852 // into a single one is that such a method would require several "if 853 // allocation is not humongous do this, otherwise do that" 854 // conditional paths which would obscure its flow. In fact, an early 855 // version of this code did use a unified method which was harder to 856 // follow and, as a result, it had subtle bugs that were hard to 857 // track down. So keeping these two methods separate allows each to 858 // be more readable. It will be good to keep these two in sync as 859 // much as possible. 860 861 assert_heap_not_locked_and_not_at_safepoint(); 862 assert(is_humongous(word_size), "attempt_allocation_humongous() " 863 "should only be called for humongous allocations"); 864 865 // Humongous objects can exhaust the heap quickly, so we should check if we 866 // need to start a marking cycle at each humongous object allocation. We do 867 // the check before we do the actual allocation. The reason for doing it 868 // before the allocation is that we avoid having to keep track of the newly 869 // allocated memory while we do a GC. 870 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 871 word_size)) { 872 collect(GCCause::_g1_humongous_allocation); 873 } 874 875 // We will loop until a) we manage to successfully perform the 876 // allocation or b) we successfully schedule a collection which 877 // fails to perform the allocation. b) is the only case when we'll 878 // return NULL. 879 HeapWord* result = NULL; 880 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 881 bool should_try_gc; 882 uint gc_count_before; 883 884 885 { 886 MutexLocker x(Heap_lock); 887 888 // Given that humongous objects are not allocated in young 889 // regions, we'll first try to do the allocation without doing a 890 // collection hoping that there's enough space in the heap. 891 result = humongous_obj_allocate(word_size); 892 if (result != NULL) { 893 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 894 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 895 return result; 896 } 897 898 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 899 // the GCLocker initiated GC has been performed and then retry. This includes 900 // the case when the GC Locker is not active but has not been performed. 901 should_try_gc = !GCLocker::needs_gc(); 902 // Read the GC count while still holding the Heap_lock. 903 gc_count_before = total_collections(); 904 } 905 906 if (should_try_gc) { 907 bool succeeded; 908 result = do_collection_pause(word_size, gc_count_before, &succeeded, 909 GCCause::_g1_humongous_allocation); 910 if (result != NULL) { 911 assert(succeeded, "only way to get back a non-NULL result"); 912 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 913 Thread::current()->name(), p2i(result)); 914 return result; 915 } 916 917 if (succeeded) { 918 // We successfully scheduled a collection which failed to allocate. No 919 // point in trying to allocate further. We'll just return NULL. 920 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 921 SIZE_FORMAT " words", Thread::current()->name(), word_size); 922 return NULL; 923 } 924 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 925 Thread::current()->name(), word_size); 926 } else { 927 // Failed to schedule a collection. 928 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 929 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 930 SIZE_FORMAT " words", Thread::current()->name(), word_size); 931 return NULL; 932 } 933 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 934 // The GCLocker is either active or the GCLocker initiated 935 // GC has not yet been performed. Stall until it is and 936 // then retry the allocation. 937 GCLocker::stall_until_clear(); 938 gclocker_retry_count += 1; 939 } 940 941 942 // We can reach here if we were unsuccessful in scheduling a 943 // collection (because another thread beat us to it) or if we were 944 // stalled due to the GC locker. In either can we should retry the 945 // allocation attempt in case another thread successfully 946 // performed a collection and reclaimed enough space. 947 // Humongous object allocation always needs a lock, so we wait for the retry 948 // in the next iteration of the loop, unlike for the regular iteration case. 949 // Give a warning if we seem to be looping forever. 950 951 if ((QueuedAllocationWarningCount > 0) && 952 (try_count % QueuedAllocationWarningCount == 0)) { 953 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 954 Thread::current()->name(), try_count, word_size); 955 } 956 } 957 958 ShouldNotReachHere(); 959 return NULL; 960 } 961 962 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 963 bool expect_null_mutator_alloc_region) { 964 assert_at_safepoint_on_vm_thread(); 965 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 966 "the current alloc region was unexpectedly found to be non-NULL"); 967 968 if (!is_humongous(word_size)) { 969 return _allocator->attempt_allocation_locked(word_size); 970 } else { 971 HeapWord* result = humongous_obj_allocate(word_size); 972 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 973 collector_state()->set_initiate_conc_mark_if_possible(true); 974 } 975 return result; 976 } 977 978 ShouldNotReachHere(); 979 } 980 981 class PostCompactionPrinterClosure: public HeapRegionClosure { 982 private: 983 G1HRPrinter* _hr_printer; 984 public: 985 bool do_heap_region(HeapRegion* hr) { 986 assert(!hr->is_young(), "not expecting to find young regions"); 987 _hr_printer->post_compaction(hr); 988 return false; 989 } 990 991 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 992 : _hr_printer(hr_printer) { } 993 }; 994 995 void G1CollectedHeap::print_hrm_post_compaction() { 996 if (_hr_printer.is_active()) { 997 PostCompactionPrinterClosure cl(hr_printer()); 998 heap_region_iterate(&cl); 999 } 1000 } 1001 1002 void G1CollectedHeap::abort_concurrent_cycle() { 1003 // If we start the compaction before the CM threads finish 1004 // scanning the root regions we might trip them over as we'll 1005 // be moving objects / updating references. So let's wait until 1006 // they are done. By telling them to abort, they should complete 1007 // early. 1008 _cm->root_regions()->abort(); 1009 _cm->root_regions()->wait_until_scan_finished(); 1010 1011 // Disable discovery and empty the discovered lists 1012 // for the CM ref processor. 1013 _ref_processor_cm->disable_discovery(); 1014 _ref_processor_cm->abandon_partial_discovery(); 1015 _ref_processor_cm->verify_no_references_recorded(); 1016 1017 // Abandon current iterations of concurrent marking and concurrent 1018 // refinement, if any are in progress. 1019 concurrent_mark()->concurrent_cycle_abort(); 1020 } 1021 1022 void G1CollectedHeap::prepare_heap_for_full_collection() { 1023 // Make sure we'll choose a new allocation region afterwards. 1024 _allocator->release_mutator_alloc_region(); 1025 _allocator->abandon_gc_alloc_regions(); 1026 1027 // We may have added regions to the current incremental collection 1028 // set between the last GC or pause and now. We need to clear the 1029 // incremental collection set and then start rebuilding it afresh 1030 // after this full GC. 1031 abandon_collection_set(collection_set()); 1032 1033 tear_down_region_sets(false /* free_list_only */); 1034 1035 hrm()->prepare_for_full_collection_start(); 1036 } 1037 1038 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1039 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1040 assert_used_and_recalculate_used_equal(this); 1041 _verifier->verify_region_sets_optional(); 1042 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1043 _verifier->check_bitmaps("Full GC Start"); 1044 } 1045 1046 void G1CollectedHeap::prepare_heap_for_mutators() { 1047 hrm()->prepare_for_full_collection_end(); 1048 1049 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1050 ClassLoaderDataGraph::purge(); 1051 MetaspaceUtils::verify_metrics(); 1052 1053 // Prepare heap for normal collections. 1054 assert(num_free_regions() == 0, "we should not have added any free regions"); 1055 rebuild_region_sets(false /* free_list_only */); 1056 abort_refinement(); 1057 resize_heap_if_necessary(); 1058 1059 // Rebuild the strong code root lists for each region 1060 rebuild_strong_code_roots(); 1061 1062 // Purge code root memory 1063 purge_code_root_memory(); 1064 1065 // Start a new incremental collection set for the next pause 1066 start_new_collection_set(); 1067 1068 _allocator->init_mutator_alloc_region(); 1069 1070 // Post collection state updates. 1071 MetaspaceGC::compute_new_size(); 1072 } 1073 1074 void G1CollectedHeap::abort_refinement() { 1075 if (_hot_card_cache->use_cache()) { 1076 _hot_card_cache->reset_hot_cache(); 1077 } 1078 1079 // Discard all remembered set updates. 1080 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1081 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1082 } 1083 1084 void G1CollectedHeap::verify_after_full_collection() { 1085 _hrm->verify_optional(); 1086 _verifier->verify_region_sets_optional(); 1087 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1088 // Clear the previous marking bitmap, if needed for bitmap verification. 1089 // Note we cannot do this when we clear the next marking bitmap in 1090 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1091 // objects marked during a full GC against the previous bitmap. 1092 // But we need to clear it before calling check_bitmaps below since 1093 // the full GC has compacted objects and updated TAMS but not updated 1094 // the prev bitmap. 1095 if (G1VerifyBitmaps) { 1096 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1097 _cm->clear_prev_bitmap(workers()); 1098 } 1099 // This call implicitly verifies that the next bitmap is clear after Full GC. 1100 _verifier->check_bitmaps("Full GC End"); 1101 1102 // At this point there should be no regions in the 1103 // entire heap tagged as young. 1104 assert(check_young_list_empty(), "young list should be empty at this point"); 1105 1106 // Note: since we've just done a full GC, concurrent 1107 // marking is no longer active. Therefore we need not 1108 // re-enable reference discovery for the CM ref processor. 1109 // That will be done at the start of the next marking cycle. 1110 // We also know that the STW processor should no longer 1111 // discover any new references. 1112 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1113 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1114 _ref_processor_stw->verify_no_references_recorded(); 1115 _ref_processor_cm->verify_no_references_recorded(); 1116 } 1117 1118 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1119 // Post collection logging. 1120 // We should do this after we potentially resize the heap so 1121 // that all the COMMIT / UNCOMMIT events are generated before 1122 // the compaction events. 1123 print_hrm_post_compaction(); 1124 heap_transition->print(); 1125 print_heap_after_gc(); 1126 print_heap_regions(); 1127 #ifdef TRACESPINNING 1128 ParallelTaskTerminator::print_termination_counts(); 1129 #endif 1130 } 1131 1132 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1133 bool clear_all_soft_refs) { 1134 assert_at_safepoint_on_vm_thread(); 1135 1136 if (GCLocker::check_active_before_gc()) { 1137 // Full GC was not completed. 1138 return false; 1139 } 1140 1141 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1142 soft_ref_policy()->should_clear_all_soft_refs(); 1143 1144 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1145 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1146 1147 collector.prepare_collection(); 1148 collector.collect(); 1149 collector.complete_collection(); 1150 1151 // Full collection was successfully completed. 1152 return true; 1153 } 1154 1155 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1156 // Currently, there is no facility in the do_full_collection(bool) API to notify 1157 // the caller that the collection did not succeed (e.g., because it was locked 1158 // out by the GC locker). So, right now, we'll ignore the return value. 1159 bool dummy = do_full_collection(true, /* explicit_gc */ 1160 clear_all_soft_refs); 1161 } 1162 1163 void G1CollectedHeap::resize_heap_if_necessary() { 1164 assert_at_safepoint_on_vm_thread(); 1165 1166 // Capacity, free and used after the GC counted as full regions to 1167 // include the waste in the following calculations. 1168 const size_t capacity_after_gc = capacity(); 1169 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1170 1171 // This is enforced in arguments.cpp. 1172 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1173 "otherwise the code below doesn't make sense"); 1174 1175 // We don't have floating point command-line arguments 1176 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1177 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1178 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1179 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1180 1181 // We have to be careful here as these two calculations can overflow 1182 // 32-bit size_t's. 1183 double used_after_gc_d = (double) used_after_gc; 1184 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1185 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1186 1187 // Let's make sure that they are both under the max heap size, which 1188 // by default will make them fit into a size_t. 1189 double desired_capacity_upper_bound = (double) MaxHeapSize; 1190 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1191 desired_capacity_upper_bound); 1192 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1193 desired_capacity_upper_bound); 1194 1195 // We can now safely turn them into size_t's. 1196 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1197 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1198 1199 // This assert only makes sense here, before we adjust them 1200 // with respect to the min and max heap size. 1201 assert(minimum_desired_capacity <= maximum_desired_capacity, 1202 "minimum_desired_capacity = " SIZE_FORMAT ", " 1203 "maximum_desired_capacity = " SIZE_FORMAT, 1204 minimum_desired_capacity, maximum_desired_capacity); 1205 1206 // Should not be greater than the heap max size. No need to adjust 1207 // it with respect to the heap min size as it's a lower bound (i.e., 1208 // we'll try to make the capacity larger than it, not smaller). 1209 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1210 // Should not be less than the heap min size. No need to adjust it 1211 // with respect to the heap max size as it's an upper bound (i.e., 1212 // we'll try to make the capacity smaller than it, not greater). 1213 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1214 1215 if (capacity_after_gc < minimum_desired_capacity) { 1216 // Don't expand unless it's significant 1217 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1218 1219 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1220 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1221 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1222 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1223 1224 expand(expand_bytes, _workers); 1225 1226 // No expansion, now see if we want to shrink 1227 } else if (capacity_after_gc > maximum_desired_capacity) { 1228 // Capacity too large, compute shrinking size 1229 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1230 1231 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1232 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1233 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1234 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1235 1236 shrink(shrink_bytes); 1237 } 1238 } 1239 1240 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1241 bool do_gc, 1242 bool clear_all_soft_refs, 1243 bool expect_null_mutator_alloc_region, 1244 bool* gc_succeeded) { 1245 *gc_succeeded = true; 1246 // Let's attempt the allocation first. 1247 HeapWord* result = 1248 attempt_allocation_at_safepoint(word_size, 1249 expect_null_mutator_alloc_region); 1250 if (result != NULL) { 1251 return result; 1252 } 1253 1254 // In a G1 heap, we're supposed to keep allocation from failing by 1255 // incremental pauses. Therefore, at least for now, we'll favor 1256 // expansion over collection. (This might change in the future if we can 1257 // do something smarter than full collection to satisfy a failed alloc.) 1258 result = expand_and_allocate(word_size); 1259 if (result != NULL) { 1260 return result; 1261 } 1262 1263 if (do_gc) { 1264 // Expansion didn't work, we'll try to do a Full GC. 1265 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1266 clear_all_soft_refs); 1267 } 1268 1269 return NULL; 1270 } 1271 1272 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1273 bool* succeeded) { 1274 assert_at_safepoint_on_vm_thread(); 1275 1276 // Attempts to allocate followed by Full GC. 1277 HeapWord* result = 1278 satisfy_failed_allocation_helper(word_size, 1279 true, /* do_gc */ 1280 false, /* clear_all_soft_refs */ 1281 false, /* expect_null_mutator_alloc_region */ 1282 succeeded); 1283 1284 if (result != NULL || !*succeeded) { 1285 return result; 1286 } 1287 1288 // Attempts to allocate followed by Full GC that will collect all soft references. 1289 result = satisfy_failed_allocation_helper(word_size, 1290 true, /* do_gc */ 1291 true, /* clear_all_soft_refs */ 1292 true, /* expect_null_mutator_alloc_region */ 1293 succeeded); 1294 1295 if (result != NULL || !*succeeded) { 1296 return result; 1297 } 1298 1299 // Attempts to allocate, no GC 1300 result = satisfy_failed_allocation_helper(word_size, 1301 false, /* do_gc */ 1302 false, /* clear_all_soft_refs */ 1303 true, /* expect_null_mutator_alloc_region */ 1304 succeeded); 1305 1306 if (result != NULL) { 1307 return result; 1308 } 1309 1310 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1311 "Flag should have been handled and cleared prior to this point"); 1312 1313 // What else? We might try synchronous finalization later. If the total 1314 // space available is large enough for the allocation, then a more 1315 // complete compaction phase than we've tried so far might be 1316 // appropriate. 1317 return NULL; 1318 } 1319 1320 // Attempting to expand the heap sufficiently 1321 // to support an allocation of the given "word_size". If 1322 // successful, perform the allocation and return the address of the 1323 // allocated block, or else "NULL". 1324 1325 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1326 assert_at_safepoint_on_vm_thread(); 1327 1328 _verifier->verify_region_sets_optional(); 1329 1330 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1331 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1332 word_size * HeapWordSize); 1333 1334 1335 if (expand(expand_bytes, _workers)) { 1336 _hrm->verify_optional(); 1337 _verifier->verify_region_sets_optional(); 1338 return attempt_allocation_at_safepoint(word_size, 1339 false /* expect_null_mutator_alloc_region */); 1340 } 1341 return NULL; 1342 } 1343 1344 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1345 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1346 aligned_expand_bytes = align_up(aligned_expand_bytes, 1347 HeapRegion::GrainBytes); 1348 1349 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1350 expand_bytes, aligned_expand_bytes); 1351 1352 if (is_maximal_no_gc()) { 1353 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1354 return false; 1355 } 1356 1357 double expand_heap_start_time_sec = os::elapsedTime(); 1358 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1359 assert(regions_to_expand > 0, "Must expand by at least one region"); 1360 1361 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1362 if (expand_time_ms != NULL) { 1363 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1364 } 1365 1366 if (expanded_by > 0) { 1367 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1368 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1369 policy()->record_new_heap_size(num_regions()); 1370 } else { 1371 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1372 1373 // The expansion of the virtual storage space was unsuccessful. 1374 // Let's see if it was because we ran out of swap. 1375 if (G1ExitOnExpansionFailure && 1376 _hrm->available() >= regions_to_expand) { 1377 // We had head room... 1378 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1379 } 1380 } 1381 return regions_to_expand > 0; 1382 } 1383 1384 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1385 size_t aligned_shrink_bytes = 1386 ReservedSpace::page_align_size_down(shrink_bytes); 1387 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1388 HeapRegion::GrainBytes); 1389 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1390 1391 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1392 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1393 1394 1395 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", 1396 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1397 if (num_regions_removed > 0) { 1398 policy()->record_new_heap_size(num_regions()); 1399 } else { 1400 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1401 } 1402 } 1403 1404 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1405 _verifier->verify_region_sets_optional(); 1406 1407 // We should only reach here at the end of a Full GC or during Remark which 1408 // means we should not not be holding to any GC alloc regions. The method 1409 // below will make sure of that and do any remaining clean up. 1410 _allocator->abandon_gc_alloc_regions(); 1411 1412 // Instead of tearing down / rebuilding the free lists here, we 1413 // could instead use the remove_all_pending() method on free_list to 1414 // remove only the ones that we need to remove. 1415 tear_down_region_sets(true /* free_list_only */); 1416 shrink_helper(shrink_bytes); 1417 rebuild_region_sets(true /* free_list_only */); 1418 1419 _hrm->verify_optional(); 1420 _verifier->verify_region_sets_optional(); 1421 } 1422 1423 class OldRegionSetChecker : public HeapRegionSetChecker { 1424 public: 1425 void check_mt_safety() { 1426 // Master Old Set MT safety protocol: 1427 // (a) If we're at a safepoint, operations on the master old set 1428 // should be invoked: 1429 // - by the VM thread (which will serialize them), or 1430 // - by the GC workers while holding the FreeList_lock, if we're 1431 // at a safepoint for an evacuation pause (this lock is taken 1432 // anyway when an GC alloc region is retired so that a new one 1433 // is allocated from the free list), or 1434 // - by the GC workers while holding the OldSets_lock, if we're at a 1435 // safepoint for a cleanup pause. 1436 // (b) If we're not at a safepoint, operations on the master old set 1437 // should be invoked while holding the Heap_lock. 1438 1439 if (SafepointSynchronize::is_at_safepoint()) { 1440 guarantee(Thread::current()->is_VM_thread() || 1441 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1442 "master old set MT safety protocol at a safepoint"); 1443 } else { 1444 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1445 } 1446 } 1447 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1448 const char* get_description() { return "Old Regions"; } 1449 }; 1450 1451 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1452 public: 1453 void check_mt_safety() { 1454 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1455 "May only change archive regions during initialization or safepoint."); 1456 } 1457 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1458 const char* get_description() { return "Archive Regions"; } 1459 }; 1460 1461 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1462 public: 1463 void check_mt_safety() { 1464 // Humongous Set MT safety protocol: 1465 // (a) If we're at a safepoint, operations on the master humongous 1466 // set should be invoked by either the VM thread (which will 1467 // serialize them) or by the GC workers while holding the 1468 // OldSets_lock. 1469 // (b) If we're not at a safepoint, operations on the master 1470 // humongous set should be invoked while holding the Heap_lock. 1471 1472 if (SafepointSynchronize::is_at_safepoint()) { 1473 guarantee(Thread::current()->is_VM_thread() || 1474 OldSets_lock->owned_by_self(), 1475 "master humongous set MT safety protocol at a safepoint"); 1476 } else { 1477 guarantee(Heap_lock->owned_by_self(), 1478 "master humongous set MT safety protocol outside a safepoint"); 1479 } 1480 } 1481 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1482 const char* get_description() { return "Humongous Regions"; } 1483 }; 1484 1485 G1CollectedHeap::G1CollectedHeap() : 1486 CollectedHeap(), 1487 _young_gen_sampling_thread(NULL), 1488 _workers(NULL), 1489 _card_table(NULL), 1490 _soft_ref_policy(), 1491 _old_set("Old Region Set", new OldRegionSetChecker()), 1492 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1493 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1494 _bot(NULL), 1495 _listener(), 1496 _hrm(NULL), 1497 _allocator(NULL), 1498 _verifier(NULL), 1499 _summary_bytes_used(0), 1500 _archive_allocator(NULL), 1501 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1502 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1503 _expand_heap_after_alloc_failure(true), 1504 _g1mm(NULL), 1505 _humongous_reclaim_candidates(), 1506 _has_humongous_reclaim_candidates(false), 1507 _hr_printer(), 1508 _collector_state(), 1509 _old_marking_cycles_started(0), 1510 _old_marking_cycles_completed(0), 1511 _eden(), 1512 _survivor(), 1513 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1514 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1515 _policy(G1Policy::create_policy(_gc_timer_stw)), 1516 _heap_sizing_policy(NULL), 1517 _collection_set(this, _policy), 1518 _hot_card_cache(NULL), 1519 _rem_set(NULL), 1520 _dirty_card_queue_set(false), 1521 _cm(NULL), 1522 _cm_thread(NULL), 1523 _cr(NULL), 1524 _task_queues(NULL), 1525 _evacuation_failed(false), 1526 _evacuation_failed_info_array(NULL), 1527 _preserved_marks_set(true /* in_c_heap */), 1528 #ifndef PRODUCT 1529 _evacuation_failure_alot_for_current_gc(false), 1530 _evacuation_failure_alot_gc_number(0), 1531 _evacuation_failure_alot_count(0), 1532 #endif 1533 _ref_processor_stw(NULL), 1534 _is_alive_closure_stw(this), 1535 _is_subject_to_discovery_stw(this), 1536 _ref_processor_cm(NULL), 1537 _is_alive_closure_cm(this), 1538 _is_subject_to_discovery_cm(this), 1539 _region_attr() { 1540 1541 _verifier = new G1HeapVerifier(this); 1542 1543 _allocator = new G1Allocator(this); 1544 1545 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1546 1547 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1548 1549 // Override the default _filler_array_max_size so that no humongous filler 1550 // objects are created. 1551 _filler_array_max_size = _humongous_object_threshold_in_words; 1552 1553 uint n_queues = ParallelGCThreads; 1554 _task_queues = new RefToScanQueueSet(n_queues); 1555 1556 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1557 1558 for (uint i = 0; i < n_queues; i++) { 1559 RefToScanQueue* q = new RefToScanQueue(); 1560 q->initialize(); 1561 _task_queues->register_queue(i, q); 1562 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1563 } 1564 1565 // Initialize the G1EvacuationFailureALot counters and flags. 1566 NOT_PRODUCT(reset_evacuation_should_fail();) 1567 1568 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1569 } 1570 1571 static size_t actual_reserved_page_size(ReservedSpace rs) { 1572 size_t page_size = os::vm_page_size(); 1573 if (UseLargePages) { 1574 // There are two ways to manage large page memory. 1575 // 1. OS supports committing large page memory. 1576 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1577 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1578 // we reserved memory without large page. 1579 if (os::can_commit_large_page_memory() || rs.special()) { 1580 // An alignment at ReservedSpace comes from preferred page size or 1581 // heap alignment, and if the alignment came from heap alignment, it could be 1582 // larger than large pages size. So need to cap with the large page size. 1583 page_size = MIN2(rs.alignment(), os::large_page_size()); 1584 } 1585 } 1586 1587 return page_size; 1588 } 1589 1590 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1591 size_t size, 1592 size_t translation_factor) { 1593 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1594 // Allocate a new reserved space, preferring to use large pages. 1595 ReservedSpace rs(size, preferred_page_size); 1596 size_t page_size = actual_reserved_page_size(rs); 1597 G1RegionToSpaceMapper* result = 1598 G1RegionToSpaceMapper::create_mapper(rs, 1599 size, 1600 page_size, 1601 HeapRegion::GrainBytes, 1602 translation_factor, 1603 mtGC); 1604 1605 os::trace_page_sizes_for_requested_size(description, 1606 size, 1607 preferred_page_size, 1608 page_size, 1609 rs.base(), 1610 rs.size()); 1611 1612 return result; 1613 } 1614 1615 jint G1CollectedHeap::initialize_concurrent_refinement() { 1616 jint ecode = JNI_OK; 1617 _cr = G1ConcurrentRefine::create(&ecode); 1618 return ecode; 1619 } 1620 1621 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1622 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1623 if (_young_gen_sampling_thread->osthread() == NULL) { 1624 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1625 return JNI_ENOMEM; 1626 } 1627 return JNI_OK; 1628 } 1629 1630 jint G1CollectedHeap::initialize() { 1631 os::enable_vtime(); 1632 1633 // Necessary to satisfy locking discipline assertions. 1634 1635 MutexLocker x(Heap_lock); 1636 1637 // While there are no constraints in the GC code that HeapWordSize 1638 // be any particular value, there are multiple other areas in the 1639 // system which believe this to be true (e.g. oop->object_size in some 1640 // cases incorrectly returns the size in wordSize units rather than 1641 // HeapWordSize). 1642 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1643 1644 size_t init_byte_size = InitialHeapSize; 1645 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1646 1647 // Ensure that the sizes are properly aligned. 1648 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1649 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1650 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1651 1652 // Reserve the maximum. 1653 1654 // When compressed oops are enabled, the preferred heap base 1655 // is calculated by subtracting the requested size from the 1656 // 32Gb boundary and using the result as the base address for 1657 // heap reservation. If the requested size is not aligned to 1658 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1659 // into the ReservedHeapSpace constructor) then the actual 1660 // base of the reserved heap may end up differing from the 1661 // address that was requested (i.e. the preferred heap base). 1662 // If this happens then we could end up using a non-optimal 1663 // compressed oops mode. 1664 1665 ReservedSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1666 HeapAlignment); 1667 1668 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1669 1670 // Create the barrier set for the entire reserved region. 1671 G1CardTable* ct = new G1CardTable(reserved_region()); 1672 ct->initialize(); 1673 G1BarrierSet* bs = new G1BarrierSet(ct); 1674 bs->initialize(); 1675 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1676 BarrierSet::set_barrier_set(bs); 1677 _card_table = ct; 1678 1679 G1BarrierSet::satb_mark_queue_set().initialize(this, 1680 SATB_Q_CBL_mon, 1681 &bs->satb_mark_queue_buffer_allocator(), 1682 G1SATBProcessCompletedThreshold, 1683 G1SATBBufferEnqueueingThresholdPercent); 1684 1685 // process_completed_buffers_threshold and max_completed_buffers are updated 1686 // later, based on the concurrent refinement object. 1687 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1688 &bs->dirty_card_queue_buffer_allocator(), 1689 true); // init_free_ids 1690 1691 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1692 &bs->dirty_card_queue_buffer_allocator()); 1693 1694 // Create the hot card cache. 1695 _hot_card_cache = new G1HotCardCache(this); 1696 1697 // Carve out the G1 part of the heap. 1698 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1699 size_t page_size = actual_reserved_page_size(heap_rs); 1700 G1RegionToSpaceMapper* heap_storage = 1701 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1702 g1_rs.size(), 1703 page_size, 1704 HeapRegion::GrainBytes, 1705 1, 1706 mtJavaHeap); 1707 if(heap_storage == NULL) { 1708 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1709 return JNI_ERR; 1710 } 1711 1712 os::trace_page_sizes("Heap", 1713 MinHeapSize, 1714 reserved_byte_size, 1715 page_size, 1716 heap_rs.base(), 1717 heap_rs.size()); 1718 heap_storage->set_mapping_changed_listener(&_listener); 1719 1720 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1721 G1RegionToSpaceMapper* bot_storage = 1722 create_aux_memory_mapper("Block Offset Table", 1723 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1724 G1BlockOffsetTable::heap_map_factor()); 1725 1726 G1RegionToSpaceMapper* cardtable_storage = 1727 create_aux_memory_mapper("Card Table", 1728 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1729 G1CardTable::heap_map_factor()); 1730 1731 G1RegionToSpaceMapper* card_counts_storage = 1732 create_aux_memory_mapper("Card Counts Table", 1733 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1734 G1CardCounts::heap_map_factor()); 1735 1736 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1737 G1RegionToSpaceMapper* prev_bitmap_storage = 1738 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1739 G1RegionToSpaceMapper* next_bitmap_storage = 1740 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1741 1742 _hrm = HeapRegionManager::create_manager(this); 1743 1744 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1745 _card_table->initialize(cardtable_storage); 1746 // Do later initialization work for concurrent refinement. 1747 _hot_card_cache->initialize(card_counts_storage); 1748 1749 // 6843694 - ensure that the maximum region index can fit 1750 // in the remembered set structures. 1751 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1752 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1753 1754 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1755 // start within the first card. 1756 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1757 // Also create a G1 rem set. 1758 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1759 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1760 1761 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1762 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1763 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1764 "too many cards per region"); 1765 1766 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1767 1768 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1769 1770 { 1771 HeapWord* start = _hrm->reserved().start(); 1772 HeapWord* end = _hrm->reserved().end(); 1773 size_t granularity = HeapRegion::GrainBytes; 1774 1775 _region_attr.initialize(start, end, granularity); 1776 _humongous_reclaim_candidates.initialize(start, end, granularity); 1777 } 1778 1779 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1780 true /* are_GC_task_threads */, 1781 false /* are_ConcurrentGC_threads */); 1782 if (_workers == NULL) { 1783 return JNI_ENOMEM; 1784 } 1785 _workers->initialize_workers(); 1786 1787 // Create the G1ConcurrentMark data structure and thread. 1788 // (Must do this late, so that "max_regions" is defined.) 1789 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1790 if (_cm == NULL || !_cm->completed_initialization()) { 1791 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1792 return JNI_ENOMEM; 1793 } 1794 _cm_thread = _cm->cm_thread(); 1795 1796 // Now expand into the initial heap size. 1797 if (!expand(init_byte_size, _workers)) { 1798 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1799 return JNI_ENOMEM; 1800 } 1801 1802 // Perform any initialization actions delegated to the policy. 1803 policy()->init(this, &_collection_set); 1804 1805 jint ecode = initialize_concurrent_refinement(); 1806 if (ecode != JNI_OK) { 1807 return ecode; 1808 } 1809 1810 ecode = initialize_young_gen_sampling_thread(); 1811 if (ecode != JNI_OK) { 1812 return ecode; 1813 } 1814 1815 { 1816 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1817 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone()); 1818 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone()); 1819 } 1820 1821 // Here we allocate the dummy HeapRegion that is required by the 1822 // G1AllocRegion class. 1823 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1824 1825 // We'll re-use the same region whether the alloc region will 1826 // require BOT updates or not and, if it doesn't, then a non-young 1827 // region will complain that it cannot support allocations without 1828 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1829 dummy_region->set_eden(); 1830 // Make sure it's full. 1831 dummy_region->set_top(dummy_region->end()); 1832 G1AllocRegion::setup(this, dummy_region); 1833 1834 _allocator->init_mutator_alloc_region(); 1835 1836 // Do create of the monitoring and management support so that 1837 // values in the heap have been properly initialized. 1838 _g1mm = new G1MonitoringSupport(this); 1839 1840 G1StringDedup::initialize(); 1841 1842 _preserved_marks_set.init(ParallelGCThreads); 1843 1844 _collection_set.initialize(max_regions()); 1845 1846 return JNI_OK; 1847 } 1848 1849 void G1CollectedHeap::stop() { 1850 // Stop all concurrent threads. We do this to make sure these threads 1851 // do not continue to execute and access resources (e.g. logging) 1852 // that are destroyed during shutdown. 1853 _cr->stop(); 1854 _young_gen_sampling_thread->stop(); 1855 _cm_thread->stop(); 1856 if (G1StringDedup::is_enabled()) { 1857 G1StringDedup::stop(); 1858 } 1859 } 1860 1861 void G1CollectedHeap::safepoint_synchronize_begin() { 1862 SuspendibleThreadSet::synchronize(); 1863 } 1864 1865 void G1CollectedHeap::safepoint_synchronize_end() { 1866 SuspendibleThreadSet::desynchronize(); 1867 } 1868 1869 void G1CollectedHeap::post_initialize() { 1870 CollectedHeap::post_initialize(); 1871 ref_processing_init(); 1872 } 1873 1874 void G1CollectedHeap::ref_processing_init() { 1875 // Reference processing in G1 currently works as follows: 1876 // 1877 // * There are two reference processor instances. One is 1878 // used to record and process discovered references 1879 // during concurrent marking; the other is used to 1880 // record and process references during STW pauses 1881 // (both full and incremental). 1882 // * Both ref processors need to 'span' the entire heap as 1883 // the regions in the collection set may be dotted around. 1884 // 1885 // * For the concurrent marking ref processor: 1886 // * Reference discovery is enabled at initial marking. 1887 // * Reference discovery is disabled and the discovered 1888 // references processed etc during remarking. 1889 // * Reference discovery is MT (see below). 1890 // * Reference discovery requires a barrier (see below). 1891 // * Reference processing may or may not be MT 1892 // (depending on the value of ParallelRefProcEnabled 1893 // and ParallelGCThreads). 1894 // * A full GC disables reference discovery by the CM 1895 // ref processor and abandons any entries on it's 1896 // discovered lists. 1897 // 1898 // * For the STW processor: 1899 // * Non MT discovery is enabled at the start of a full GC. 1900 // * Processing and enqueueing during a full GC is non-MT. 1901 // * During a full GC, references are processed after marking. 1902 // 1903 // * Discovery (may or may not be MT) is enabled at the start 1904 // of an incremental evacuation pause. 1905 // * References are processed near the end of a STW evacuation pause. 1906 // * For both types of GC: 1907 // * Discovery is atomic - i.e. not concurrent. 1908 // * Reference discovery will not need a barrier. 1909 1910 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1911 1912 // Concurrent Mark ref processor 1913 _ref_processor_cm = 1914 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1915 mt_processing, // mt processing 1916 ParallelGCThreads, // degree of mt processing 1917 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1918 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1919 false, // Reference discovery is not atomic 1920 &_is_alive_closure_cm, // is alive closure 1921 true); // allow changes to number of processing threads 1922 1923 // STW ref processor 1924 _ref_processor_stw = 1925 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1926 mt_processing, // mt processing 1927 ParallelGCThreads, // degree of mt processing 1928 (ParallelGCThreads > 1), // mt discovery 1929 ParallelGCThreads, // degree of mt discovery 1930 true, // Reference discovery is atomic 1931 &_is_alive_closure_stw, // is alive closure 1932 true); // allow changes to number of processing threads 1933 } 1934 1935 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1936 return &_soft_ref_policy; 1937 } 1938 1939 size_t G1CollectedHeap::capacity() const { 1940 return _hrm->length() * HeapRegion::GrainBytes; 1941 } 1942 1943 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1944 return _hrm->total_free_bytes(); 1945 } 1946 1947 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1948 _hot_card_cache->drain(cl, worker_i); 1949 } 1950 1951 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1952 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1953 size_t n_completed_buffers = 0; 1954 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1955 n_completed_buffers++; 1956 } 1957 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!"); 1958 phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1959 } 1960 1961 // Computes the sum of the storage used by the various regions. 1962 size_t G1CollectedHeap::used() const { 1963 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1964 if (_archive_allocator != NULL) { 1965 result += _archive_allocator->used(); 1966 } 1967 return result; 1968 } 1969 1970 size_t G1CollectedHeap::used_unlocked() const { 1971 return _summary_bytes_used; 1972 } 1973 1974 class SumUsedClosure: public HeapRegionClosure { 1975 size_t _used; 1976 public: 1977 SumUsedClosure() : _used(0) {} 1978 bool do_heap_region(HeapRegion* r) { 1979 _used += r->used(); 1980 return false; 1981 } 1982 size_t result() { return _used; } 1983 }; 1984 1985 size_t G1CollectedHeap::recalculate_used() const { 1986 SumUsedClosure blk; 1987 heap_region_iterate(&blk); 1988 return blk.result(); 1989 } 1990 1991 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1992 switch (cause) { 1993 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1994 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1995 case GCCause::_wb_conc_mark: return true; 1996 default : return false; 1997 } 1998 } 1999 2000 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2001 switch (cause) { 2002 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2003 case GCCause::_g1_humongous_allocation: return true; 2004 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2005 default: return is_user_requested_concurrent_full_gc(cause); 2006 } 2007 } 2008 2009 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2010 if(policy()->force_upgrade_to_full()) { 2011 return true; 2012 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2013 return false; 2014 } else if (has_regions_left_for_allocation()) { 2015 return false; 2016 } else { 2017 return true; 2018 } 2019 } 2020 2021 #ifndef PRODUCT 2022 void G1CollectedHeap::allocate_dummy_regions() { 2023 // Let's fill up most of the region 2024 size_t word_size = HeapRegion::GrainWords - 1024; 2025 // And as a result the region we'll allocate will be humongous. 2026 guarantee(is_humongous(word_size), "sanity"); 2027 2028 // _filler_array_max_size is set to humongous object threshold 2029 // but temporarily change it to use CollectedHeap::fill_with_object(). 2030 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2031 2032 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2033 // Let's use the existing mechanism for the allocation 2034 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2035 if (dummy_obj != NULL) { 2036 MemRegion mr(dummy_obj, word_size); 2037 CollectedHeap::fill_with_object(mr); 2038 } else { 2039 // If we can't allocate once, we probably cannot allocate 2040 // again. Let's get out of the loop. 2041 break; 2042 } 2043 } 2044 } 2045 #endif // !PRODUCT 2046 2047 void G1CollectedHeap::increment_old_marking_cycles_started() { 2048 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2049 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2050 "Wrong marking cycle count (started: %d, completed: %d)", 2051 _old_marking_cycles_started, _old_marking_cycles_completed); 2052 2053 _old_marking_cycles_started++; 2054 } 2055 2056 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2057 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2058 2059 // We assume that if concurrent == true, then the caller is a 2060 // concurrent thread that was joined the Suspendible Thread 2061 // Set. If there's ever a cheap way to check this, we should add an 2062 // assert here. 2063 2064 // Given that this method is called at the end of a Full GC or of a 2065 // concurrent cycle, and those can be nested (i.e., a Full GC can 2066 // interrupt a concurrent cycle), the number of full collections 2067 // completed should be either one (in the case where there was no 2068 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2069 // behind the number of full collections started. 2070 2071 // This is the case for the inner caller, i.e. a Full GC. 2072 assert(concurrent || 2073 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2074 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2075 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2076 "is inconsistent with _old_marking_cycles_completed = %u", 2077 _old_marking_cycles_started, _old_marking_cycles_completed); 2078 2079 // This is the case for the outer caller, i.e. the concurrent cycle. 2080 assert(!concurrent || 2081 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2082 "for outer caller (concurrent cycle): " 2083 "_old_marking_cycles_started = %u " 2084 "is inconsistent with _old_marking_cycles_completed = %u", 2085 _old_marking_cycles_started, _old_marking_cycles_completed); 2086 2087 _old_marking_cycles_completed += 1; 2088 2089 // We need to clear the "in_progress" flag in the CM thread before 2090 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2091 // is set) so that if a waiter requests another System.gc() it doesn't 2092 // incorrectly see that a marking cycle is still in progress. 2093 if (concurrent) { 2094 _cm_thread->set_idle(); 2095 } 2096 2097 // This notify_all() will ensure that a thread that called 2098 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2099 // and it's waiting for a full GC to finish will be woken up. It is 2100 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2101 FullGCCount_lock->notify_all(); 2102 } 2103 2104 void G1CollectedHeap::collect(GCCause::Cause cause) { 2105 try_collect(cause, true); 2106 } 2107 2108 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2109 assert_heap_not_locked(); 2110 2111 bool gc_succeeded; 2112 bool should_retry_gc; 2113 2114 do { 2115 should_retry_gc = false; 2116 2117 uint gc_count_before; 2118 uint old_marking_count_before; 2119 uint full_gc_count_before; 2120 2121 { 2122 MutexLocker ml(Heap_lock); 2123 2124 // Read the GC count while holding the Heap_lock 2125 gc_count_before = total_collections(); 2126 full_gc_count_before = total_full_collections(); 2127 old_marking_count_before = _old_marking_cycles_started; 2128 } 2129 2130 if (should_do_concurrent_full_gc(cause)) { 2131 // Schedule an initial-mark evacuation pause that will start a 2132 // concurrent cycle. We're setting word_size to 0 which means that 2133 // we are not requesting a post-GC allocation. 2134 VM_G1CollectForAllocation op(0, /* word_size */ 2135 gc_count_before, 2136 cause, 2137 true, /* should_initiate_conc_mark */ 2138 policy()->max_pause_time_ms()); 2139 VMThread::execute(&op); 2140 gc_succeeded = op.gc_succeeded(); 2141 if (!gc_succeeded && retry_on_gc_failure) { 2142 if (old_marking_count_before == _old_marking_cycles_started) { 2143 should_retry_gc = op.should_retry_gc(); 2144 } else { 2145 // A Full GC happened while we were trying to schedule the 2146 // concurrent cycle. No point in starting a new cycle given 2147 // that the whole heap was collected anyway. 2148 } 2149 2150 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2151 GCLocker::stall_until_clear(); 2152 } 2153 } 2154 } else { 2155 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2156 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2157 2158 // Schedule a standard evacuation pause. We're setting word_size 2159 // to 0 which means that we are not requesting a post-GC allocation. 2160 VM_G1CollectForAllocation op(0, /* word_size */ 2161 gc_count_before, 2162 cause, 2163 false, /* should_initiate_conc_mark */ 2164 policy()->max_pause_time_ms()); 2165 VMThread::execute(&op); 2166 gc_succeeded = op.gc_succeeded(); 2167 } else { 2168 // Schedule a Full GC. 2169 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2170 VMThread::execute(&op); 2171 gc_succeeded = op.gc_succeeded(); 2172 } 2173 } 2174 } while (should_retry_gc); 2175 return gc_succeeded; 2176 } 2177 2178 bool G1CollectedHeap::is_in(const void* p) const { 2179 if (_hrm->reserved().contains(p)) { 2180 // Given that we know that p is in the reserved space, 2181 // heap_region_containing() should successfully 2182 // return the containing region. 2183 HeapRegion* hr = heap_region_containing(p); 2184 return hr->is_in(p); 2185 } else { 2186 return false; 2187 } 2188 } 2189 2190 #ifdef ASSERT 2191 bool G1CollectedHeap::is_in_exact(const void* p) const { 2192 bool contains = reserved_region().contains(p); 2193 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2194 if (contains && available) { 2195 return true; 2196 } else { 2197 return false; 2198 } 2199 } 2200 #endif 2201 2202 // Iteration functions. 2203 2204 // Iterates an ObjectClosure over all objects within a HeapRegion. 2205 2206 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2207 ObjectClosure* _cl; 2208 public: 2209 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2210 bool do_heap_region(HeapRegion* r) { 2211 if (!r->is_continues_humongous()) { 2212 r->object_iterate(_cl); 2213 } 2214 return false; 2215 } 2216 }; 2217 2218 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2219 IterateObjectClosureRegionClosure blk(cl); 2220 heap_region_iterate(&blk); 2221 } 2222 2223 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2224 _hrm->iterate(cl); 2225 } 2226 2227 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2228 HeapRegionClaimer *hrclaimer, 2229 uint worker_id) const { 2230 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2231 } 2232 2233 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2234 HeapRegionClaimer *hrclaimer) const { 2235 _hrm->par_iterate(cl, hrclaimer, 0); 2236 } 2237 2238 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2239 _collection_set.iterate(cl); 2240 } 2241 2242 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, uint worker_id) { 2243 _collection_set.iterate_incremental_part_from(cl, worker_id, workers()->active_workers()); 2244 } 2245 2246 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2247 HeapRegion* hr = heap_region_containing(addr); 2248 return hr->block_start(addr); 2249 } 2250 2251 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2252 HeapRegion* hr = heap_region_containing(addr); 2253 return hr->block_is_obj(addr); 2254 } 2255 2256 bool G1CollectedHeap::supports_tlab_allocation() const { 2257 return true; 2258 } 2259 2260 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2261 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2262 } 2263 2264 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2265 return _eden.length() * HeapRegion::GrainBytes; 2266 } 2267 2268 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2269 // must be equal to the humongous object limit. 2270 size_t G1CollectedHeap::max_tlab_size() const { 2271 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2272 } 2273 2274 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2275 return _allocator->unsafe_max_tlab_alloc(); 2276 } 2277 2278 size_t G1CollectedHeap::max_capacity() const { 2279 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2280 } 2281 2282 size_t G1CollectedHeap::max_reserved_capacity() const { 2283 return _hrm->max_length() * HeapRegion::GrainBytes; 2284 } 2285 2286 jlong G1CollectedHeap::millis_since_last_gc() { 2287 // See the notes in GenCollectedHeap::millis_since_last_gc() 2288 // for more information about the implementation. 2289 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2290 _policy->collection_pause_end_millis(); 2291 if (ret_val < 0) { 2292 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2293 ". returning zero instead.", ret_val); 2294 return 0; 2295 } 2296 return ret_val; 2297 } 2298 2299 void G1CollectedHeap::deduplicate_string(oop str) { 2300 assert(java_lang_String::is_instance(str), "invariant"); 2301 2302 if (G1StringDedup::is_enabled()) { 2303 G1StringDedup::deduplicate(str); 2304 } 2305 } 2306 2307 void G1CollectedHeap::prepare_for_verify() { 2308 _verifier->prepare_for_verify(); 2309 } 2310 2311 void G1CollectedHeap::verify(VerifyOption vo) { 2312 _verifier->verify(vo); 2313 } 2314 2315 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2316 return true; 2317 } 2318 2319 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2320 return _cm_thread->request_concurrent_phase(phase); 2321 } 2322 2323 bool G1CollectedHeap::is_heterogeneous_heap() const { 2324 return G1Arguments::is_heterogeneous_heap(); 2325 } 2326 2327 class PrintRegionClosure: public HeapRegionClosure { 2328 outputStream* _st; 2329 public: 2330 PrintRegionClosure(outputStream* st) : _st(st) {} 2331 bool do_heap_region(HeapRegion* r) { 2332 r->print_on(_st); 2333 return false; 2334 } 2335 }; 2336 2337 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2338 const HeapRegion* hr, 2339 const VerifyOption vo) const { 2340 switch (vo) { 2341 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2342 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2343 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2344 default: ShouldNotReachHere(); 2345 } 2346 return false; // keep some compilers happy 2347 } 2348 2349 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2350 const VerifyOption vo) const { 2351 switch (vo) { 2352 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2353 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2354 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2355 default: ShouldNotReachHere(); 2356 } 2357 return false; // keep some compilers happy 2358 } 2359 2360 void G1CollectedHeap::print_heap_regions() const { 2361 LogTarget(Trace, gc, heap, region) lt; 2362 if (lt.is_enabled()) { 2363 LogStream ls(lt); 2364 print_regions_on(&ls); 2365 } 2366 } 2367 2368 void G1CollectedHeap::print_on(outputStream* st) const { 2369 st->print(" %-20s", "garbage-first heap"); 2370 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2371 capacity()/K, used_unlocked()/K); 2372 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2373 p2i(_hrm->reserved().start()), 2374 p2i(_hrm->reserved().end())); 2375 st->cr(); 2376 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2377 uint young_regions = young_regions_count(); 2378 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2379 (size_t) young_regions * HeapRegion::GrainBytes / K); 2380 uint survivor_regions = survivor_regions_count(); 2381 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2382 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2383 st->cr(); 2384 MetaspaceUtils::print_on(st); 2385 } 2386 2387 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2388 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2389 "HS=humongous(starts), HC=humongous(continues), " 2390 "CS=collection set, F=free, A=archive, " 2391 "TAMS=top-at-mark-start (previous, next)"); 2392 PrintRegionClosure blk(st); 2393 heap_region_iterate(&blk); 2394 } 2395 2396 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2397 print_on(st); 2398 2399 // Print the per-region information. 2400 print_regions_on(st); 2401 } 2402 2403 void G1CollectedHeap::print_on_error(outputStream* st) const { 2404 this->CollectedHeap::print_on_error(st); 2405 2406 if (_cm != NULL) { 2407 st->cr(); 2408 _cm->print_on_error(st); 2409 } 2410 } 2411 2412 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2413 workers()->print_worker_threads_on(st); 2414 _cm_thread->print_on(st); 2415 st->cr(); 2416 _cm->print_worker_threads_on(st); 2417 _cr->print_threads_on(st); 2418 _young_gen_sampling_thread->print_on(st); 2419 if (G1StringDedup::is_enabled()) { 2420 G1StringDedup::print_worker_threads_on(st); 2421 } 2422 } 2423 2424 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2425 workers()->threads_do(tc); 2426 tc->do_thread(_cm_thread); 2427 _cm->threads_do(tc); 2428 _cr->threads_do(tc); 2429 tc->do_thread(_young_gen_sampling_thread); 2430 if (G1StringDedup::is_enabled()) { 2431 G1StringDedup::threads_do(tc); 2432 } 2433 } 2434 2435 void G1CollectedHeap::print_tracing_info() const { 2436 rem_set()->print_summary_info(); 2437 concurrent_mark()->print_summary_info(); 2438 } 2439 2440 #ifndef PRODUCT 2441 // Helpful for debugging RSet issues. 2442 2443 class PrintRSetsClosure : public HeapRegionClosure { 2444 private: 2445 const char* _msg; 2446 size_t _occupied_sum; 2447 2448 public: 2449 bool do_heap_region(HeapRegion* r) { 2450 HeapRegionRemSet* hrrs = r->rem_set(); 2451 size_t occupied = hrrs->occupied(); 2452 _occupied_sum += occupied; 2453 2454 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2455 if (occupied == 0) { 2456 tty->print_cr(" RSet is empty"); 2457 } else { 2458 hrrs->print(); 2459 } 2460 tty->print_cr("----------"); 2461 return false; 2462 } 2463 2464 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2465 tty->cr(); 2466 tty->print_cr("========================================"); 2467 tty->print_cr("%s", msg); 2468 tty->cr(); 2469 } 2470 2471 ~PrintRSetsClosure() { 2472 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2473 tty->print_cr("========================================"); 2474 tty->cr(); 2475 } 2476 }; 2477 2478 void G1CollectedHeap::print_cset_rsets() { 2479 PrintRSetsClosure cl("Printing CSet RSets"); 2480 collection_set_iterate_all(&cl); 2481 } 2482 2483 void G1CollectedHeap::print_all_rsets() { 2484 PrintRSetsClosure cl("Printing All RSets");; 2485 heap_region_iterate(&cl); 2486 } 2487 #endif // PRODUCT 2488 2489 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2490 2491 size_t eden_used_bytes = _eden.used_bytes(); 2492 size_t survivor_used_bytes = _survivor.used_bytes(); 2493 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2494 2495 size_t eden_capacity_bytes = 2496 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2497 2498 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2499 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2500 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2501 } 2502 2503 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2504 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2505 stats->unused(), stats->used(), stats->region_end_waste(), 2506 stats->regions_filled(), stats->direct_allocated(), 2507 stats->failure_used(), stats->failure_waste()); 2508 } 2509 2510 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2511 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2512 gc_tracer->report_gc_heap_summary(when, heap_summary); 2513 2514 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2515 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2516 } 2517 2518 G1CollectedHeap* G1CollectedHeap::heap() { 2519 CollectedHeap* heap = Universe::heap(); 2520 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2521 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2522 return (G1CollectedHeap*)heap; 2523 } 2524 2525 void G1CollectedHeap::gc_prologue(bool full) { 2526 // always_do_update_barrier = false; 2527 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2528 2529 // This summary needs to be printed before incrementing total collections. 2530 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2531 2532 // Update common counters. 2533 increment_total_collections(full /* full gc */); 2534 if (full || collector_state()->in_initial_mark_gc()) { 2535 increment_old_marking_cycles_started(); 2536 } 2537 2538 // Fill TLAB's and such 2539 double start = os::elapsedTime(); 2540 ensure_parsability(true); 2541 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2542 } 2543 2544 void G1CollectedHeap::gc_epilogue(bool full) { 2545 // Update common counters. 2546 if (full) { 2547 // Update the number of full collections that have been completed. 2548 increment_old_marking_cycles_completed(false /* concurrent */); 2549 } 2550 2551 // We are at the end of the GC. Total collections has already been increased. 2552 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2553 2554 // FIXME: what is this about? 2555 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2556 // is set. 2557 #if COMPILER2_OR_JVMCI 2558 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2559 #endif 2560 // always_do_update_barrier = true; 2561 2562 double start = os::elapsedTime(); 2563 resize_all_tlabs(); 2564 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2565 2566 MemoryService::track_memory_usage(); 2567 // We have just completed a GC. Update the soft reference 2568 // policy with the new heap occupancy 2569 Universe::update_heap_info_at_gc(); 2570 } 2571 2572 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2573 uint gc_count_before, 2574 bool* succeeded, 2575 GCCause::Cause gc_cause) { 2576 assert_heap_not_locked_and_not_at_safepoint(); 2577 VM_G1CollectForAllocation op(word_size, 2578 gc_count_before, 2579 gc_cause, 2580 false, /* should_initiate_conc_mark */ 2581 policy()->max_pause_time_ms()); 2582 VMThread::execute(&op); 2583 2584 HeapWord* result = op.result(); 2585 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2586 assert(result == NULL || ret_succeeded, 2587 "the result should be NULL if the VM did not succeed"); 2588 *succeeded = ret_succeeded; 2589 2590 assert_heap_not_locked(); 2591 return result; 2592 } 2593 2594 void G1CollectedHeap::do_concurrent_mark() { 2595 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2596 if (!_cm_thread->in_progress()) { 2597 _cm_thread->set_started(); 2598 CGC_lock->notify(); 2599 } 2600 } 2601 2602 size_t G1CollectedHeap::pending_card_num() { 2603 struct CountCardsClosure : public ThreadClosure { 2604 size_t _cards; 2605 CountCardsClosure() : _cards(0) {} 2606 virtual void do_thread(Thread* t) { 2607 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2608 } 2609 } count_from_threads; 2610 Threads::threads_do(&count_from_threads); 2611 2612 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2613 size_t buffer_size = dcqs.buffer_size(); 2614 size_t buffer_num = dcqs.completed_buffers_num(); 2615 2616 return buffer_size * buffer_num + count_from_threads._cards; 2617 } 2618 2619 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2620 // We don't nominate objects with many remembered set entries, on 2621 // the assumption that such objects are likely still live. 2622 HeapRegionRemSet* rem_set = r->rem_set(); 2623 2624 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2625 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2626 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2627 } 2628 2629 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2630 private: 2631 size_t _total_humongous; 2632 size_t _candidate_humongous; 2633 2634 G1DirtyCardQueue _dcq; 2635 2636 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2637 assert(region->is_starts_humongous(), "Must start a humongous object"); 2638 2639 oop obj = oop(region->bottom()); 2640 2641 // Dead objects cannot be eager reclaim candidates. Due to class 2642 // unloading it is unsafe to query their classes so we return early. 2643 if (g1h->is_obj_dead(obj, region)) { 2644 return false; 2645 } 2646 2647 // If we do not have a complete remembered set for the region, then we can 2648 // not be sure that we have all references to it. 2649 if (!region->rem_set()->is_complete()) { 2650 return false; 2651 } 2652 // Candidate selection must satisfy the following constraints 2653 // while concurrent marking is in progress: 2654 // 2655 // * In order to maintain SATB invariants, an object must not be 2656 // reclaimed if it was allocated before the start of marking and 2657 // has not had its references scanned. Such an object must have 2658 // its references (including type metadata) scanned to ensure no 2659 // live objects are missed by the marking process. Objects 2660 // allocated after the start of concurrent marking don't need to 2661 // be scanned. 2662 // 2663 // * An object must not be reclaimed if it is on the concurrent 2664 // mark stack. Objects allocated after the start of concurrent 2665 // marking are never pushed on the mark stack. 2666 // 2667 // Nominating only objects allocated after the start of concurrent 2668 // marking is sufficient to meet both constraints. This may miss 2669 // some objects that satisfy the constraints, but the marking data 2670 // structures don't support efficiently performing the needed 2671 // additional tests or scrubbing of the mark stack. 2672 // 2673 // However, we presently only nominate is_typeArray() objects. 2674 // A humongous object containing references induces remembered 2675 // set entries on other regions. In order to reclaim such an 2676 // object, those remembered sets would need to be cleaned up. 2677 // 2678 // We also treat is_typeArray() objects specially, allowing them 2679 // to be reclaimed even if allocated before the start of 2680 // concurrent mark. For this we rely on mark stack insertion to 2681 // exclude is_typeArray() objects, preventing reclaiming an object 2682 // that is in the mark stack. We also rely on the metadata for 2683 // such objects to be built-in and so ensured to be kept live. 2684 // Frequent allocation and drop of large binary blobs is an 2685 // important use case for eager reclaim, and this special handling 2686 // may reduce needed headroom. 2687 2688 return obj->is_typeArray() && 2689 g1h->is_potential_eager_reclaim_candidate(region); 2690 } 2691 2692 public: 2693 RegisterRegionsWithRegionAttrTableClosure() 2694 : _total_humongous(0), 2695 _candidate_humongous(0), 2696 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2697 } 2698 2699 virtual bool do_heap_region(HeapRegion* r) { 2700 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2701 2702 if (!r->is_starts_humongous()) { 2703 g1h->register_region_with_region_attr(r); 2704 return false; 2705 } 2706 2707 bool is_candidate = humongous_region_is_candidate(g1h, r); 2708 uint rindex = r->hrm_index(); 2709 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2710 if (is_candidate) { 2711 _candidate_humongous++; 2712 g1h->register_humongous_region_with_region_attr(rindex); 2713 // Is_candidate already filters out humongous object with large remembered sets. 2714 // If we have a humongous object with a few remembered sets, we simply flush these 2715 // remembered set entries into the DCQS. That will result in automatic 2716 // re-evaluation of their remembered set entries during the following evacuation 2717 // phase. 2718 if (!r->rem_set()->is_empty()) { 2719 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2720 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2721 G1CardTable* ct = g1h->card_table(); 2722 HeapRegionRemSetIterator hrrs(r->rem_set()); 2723 size_t card_index; 2724 while (hrrs.has_next(card_index)) { 2725 CardTable::CardValue* card_ptr = ct->byte_for_index(card_index); 2726 // The remembered set might contain references to already freed 2727 // regions. Filter out such entries to avoid failing card table 2728 // verification. 2729 if (g1h->is_in(ct->addr_for(card_ptr))) { 2730 if (*card_ptr != G1CardTable::dirty_card_val()) { 2731 *card_ptr = G1CardTable::dirty_card_val(); 2732 _dcq.enqueue(card_ptr); 2733 } 2734 } 2735 } 2736 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2737 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2738 hrrs.n_yielded(), r->rem_set()->occupied()); 2739 // We should only clear the card based remembered set here as we will not 2740 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2741 // (and probably never) we do not enter this path if there are other kind of 2742 // remembered sets for this region. 2743 r->rem_set()->clear_locked(true /* only_cardset */); 2744 // Clear_locked() above sets the state to Empty. However we want to continue 2745 // collecting remembered set entries for humongous regions that were not 2746 // reclaimed. 2747 r->rem_set()->set_state_complete(); 2748 #ifdef ASSERT 2749 G1HeapRegionAttr region_attr = g1h->region_attr(oop(r->bottom())); 2750 assert(region_attr.needs_remset_update(), "must be"); 2751 #endif 2752 } 2753 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2754 } else { 2755 g1h->register_region_with_region_attr(r); 2756 } 2757 _total_humongous++; 2758 2759 return false; 2760 } 2761 2762 size_t total_humongous() const { return _total_humongous; } 2763 size_t candidate_humongous() const { return _candidate_humongous; } 2764 2765 void flush_rem_set_entries() { _dcq.flush(); } 2766 }; 2767 2768 void G1CollectedHeap::register_regions_with_region_attr() { 2769 Ticks start = Ticks::now(); 2770 2771 RegisterRegionsWithRegionAttrTableClosure cl; 2772 heap_region_iterate(&cl); 2773 2774 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2775 cl.total_humongous(), 2776 cl.candidate_humongous()); 2777 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2778 2779 // Finally flush all remembered set entries to re-check into the global DCQS. 2780 cl.flush_rem_set_entries(); 2781 } 2782 2783 #ifndef PRODUCT 2784 void G1CollectedHeap::verify_region_attr_remset_update() { 2785 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2786 public: 2787 virtual bool do_heap_region(HeapRegion* r) { 2788 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2789 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2790 assert(r->rem_set()->is_tracked() == needs_remset_update, 2791 "Region %u remset tracking status (%s) different to region attribute (%s)", 2792 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2793 return false; 2794 } 2795 } cl; 2796 heap_region_iterate(&cl); 2797 } 2798 #endif 2799 2800 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2801 public: 2802 bool do_heap_region(HeapRegion* hr) { 2803 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2804 hr->verify_rem_set(); 2805 } 2806 return false; 2807 } 2808 }; 2809 2810 uint G1CollectedHeap::num_task_queues() const { 2811 return _task_queues->size(); 2812 } 2813 2814 #if TASKQUEUE_STATS 2815 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2816 st->print_raw_cr("GC Task Stats"); 2817 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2818 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2819 } 2820 2821 void G1CollectedHeap::print_taskqueue_stats() const { 2822 if (!log_is_enabled(Trace, gc, task, stats)) { 2823 return; 2824 } 2825 Log(gc, task, stats) log; 2826 ResourceMark rm; 2827 LogStream ls(log.trace()); 2828 outputStream* st = &ls; 2829 2830 print_taskqueue_stats_hdr(st); 2831 2832 TaskQueueStats totals; 2833 const uint n = num_task_queues(); 2834 for (uint i = 0; i < n; ++i) { 2835 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2836 totals += task_queue(i)->stats; 2837 } 2838 st->print_raw("tot "); totals.print(st); st->cr(); 2839 2840 DEBUG_ONLY(totals.verify()); 2841 } 2842 2843 void G1CollectedHeap::reset_taskqueue_stats() { 2844 const uint n = num_task_queues(); 2845 for (uint i = 0; i < n; ++i) { 2846 task_queue(i)->stats.reset(); 2847 } 2848 } 2849 #endif // TASKQUEUE_STATS 2850 2851 void G1CollectedHeap::wait_for_root_region_scanning() { 2852 double scan_wait_start = os::elapsedTime(); 2853 // We have to wait until the CM threads finish scanning the 2854 // root regions as it's the only way to ensure that all the 2855 // objects on them have been correctly scanned before we start 2856 // moving them during the GC. 2857 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2858 double wait_time_ms = 0.0; 2859 if (waited) { 2860 double scan_wait_end = os::elapsedTime(); 2861 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2862 } 2863 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2864 } 2865 2866 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2867 private: 2868 G1HRPrinter* _hr_printer; 2869 public: 2870 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2871 2872 virtual bool do_heap_region(HeapRegion* r) { 2873 _hr_printer->cset(r); 2874 return false; 2875 } 2876 }; 2877 2878 void G1CollectedHeap::start_new_collection_set() { 2879 double start = os::elapsedTime(); 2880 2881 collection_set()->start_incremental_building(); 2882 2883 clear_region_attr(); 2884 2885 guarantee(_eden.length() == 0, "eden should have been cleared"); 2886 policy()->transfer_survivors_to_cset(survivor()); 2887 2888 // We redo the verification but now wrt to the new CSet which 2889 // has just got initialized after the previous CSet was freed. 2890 _cm->verify_no_collection_set_oops(); 2891 2892 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2893 } 2894 2895 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2896 2897 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2898 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2899 collection_set()->optional_region_length()); 2900 2901 _cm->verify_no_collection_set_oops(); 2902 2903 if (_hr_printer.is_active()) { 2904 G1PrintCollectionSetClosure cl(&_hr_printer); 2905 _collection_set.iterate(&cl); 2906 _collection_set.iterate_optional(&cl); 2907 } 2908 } 2909 2910 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2911 if (collector_state()->in_initial_mark_gc()) { 2912 return G1HeapVerifier::G1VerifyConcurrentStart; 2913 } else if (collector_state()->in_young_only_phase()) { 2914 return G1HeapVerifier::G1VerifyYoungNormal; 2915 } else { 2916 return G1HeapVerifier::G1VerifyMixed; 2917 } 2918 } 2919 2920 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2921 if (VerifyRememberedSets) { 2922 log_info(gc, verify)("[Verifying RemSets before GC]"); 2923 VerifyRegionRemSetClosure v_cl; 2924 heap_region_iterate(&v_cl); 2925 } 2926 _verifier->verify_before_gc(type); 2927 _verifier->check_bitmaps("GC Start"); 2928 } 2929 2930 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2931 if (VerifyRememberedSets) { 2932 log_info(gc, verify)("[Verifying RemSets after GC]"); 2933 VerifyRegionRemSetClosure v_cl; 2934 heap_region_iterate(&v_cl); 2935 } 2936 _verifier->verify_after_gc(type); 2937 _verifier->check_bitmaps("GC End"); 2938 } 2939 2940 void G1CollectedHeap::expand_heap_after_young_collection(){ 2941 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2942 if (expand_bytes > 0) { 2943 // No need for an ergo logging here, 2944 // expansion_amount() does this when it returns a value > 0. 2945 double expand_ms; 2946 if (!expand(expand_bytes, _workers, &expand_ms)) { 2947 // We failed to expand the heap. Cannot do anything about it. 2948 } 2949 phase_times()->record_expand_heap_time(expand_ms); 2950 } 2951 } 2952 2953 const char* G1CollectedHeap::young_gc_name() const { 2954 if (collector_state()->in_initial_mark_gc()) { 2955 return "Pause Young (Concurrent Start)"; 2956 } else if (collector_state()->in_young_only_phase()) { 2957 if (collector_state()->in_young_gc_before_mixed()) { 2958 return "Pause Young (Prepare Mixed)"; 2959 } else { 2960 return "Pause Young (Normal)"; 2961 } 2962 } else { 2963 return "Pause Young (Mixed)"; 2964 } 2965 } 2966 2967 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2968 assert_at_safepoint_on_vm_thread(); 2969 guarantee(!is_gc_active(), "collection is not reentrant"); 2970 2971 if (GCLocker::check_active_before_gc()) { 2972 return false; 2973 } 2974 2975 GCIdMark gc_id_mark; 2976 2977 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2978 ResourceMark rm; 2979 2980 policy()->note_gc_start(); 2981 2982 _gc_timer_stw->register_gc_start(); 2983 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2984 2985 wait_for_root_region_scanning(); 2986 2987 print_heap_before_gc(); 2988 print_heap_regions(); 2989 trace_heap_before_gc(_gc_tracer_stw); 2990 2991 _verifier->verify_region_sets_optional(); 2992 _verifier->verify_dirty_young_regions(); 2993 2994 // We should not be doing initial mark unless the conc mark thread is running 2995 if (!_cm_thread->should_terminate()) { 2996 // This call will decide whether this pause is an initial-mark 2997 // pause. If it is, in_initial_mark_gc() will return true 2998 // for the duration of this pause. 2999 policy()->decide_on_conc_mark_initiation(); 3000 } 3001 3002 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3003 assert(!collector_state()->in_initial_mark_gc() || 3004 collector_state()->in_young_only_phase(), "sanity"); 3005 // We also do not allow mixed GCs during marking. 3006 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 3007 3008 // Record whether this pause is an initial mark. When the current 3009 // thread has completed its logging output and it's safe to signal 3010 // the CM thread, the flag's value in the policy has been reset. 3011 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 3012 if (should_start_conc_mark) { 3013 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3014 } 3015 3016 // Inner scope for scope based logging, timers, and stats collection 3017 { 3018 G1EvacuationInfo evacuation_info; 3019 3020 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3021 3022 GCTraceCPUTime tcpu; 3023 3024 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3025 3026 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3027 workers()->active_workers(), 3028 Threads::number_of_non_daemon_threads()); 3029 active_workers = workers()->update_active_workers(active_workers); 3030 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3031 3032 G1MonitoringScope ms(g1mm(), 3033 false /* full_gc */, 3034 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3035 3036 G1HeapTransition heap_transition(this); 3037 size_t heap_used_bytes_before_gc = used(); 3038 3039 { 3040 IsGCActiveMark x; 3041 3042 gc_prologue(false); 3043 3044 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3045 verify_before_young_collection(verify_type); 3046 3047 { 3048 // The elapsed time induced by the start time below deliberately elides 3049 // the possible verification above. 3050 double sample_start_time_sec = os::elapsedTime(); 3051 3052 // Please see comment in g1CollectedHeap.hpp and 3053 // G1CollectedHeap::ref_processing_init() to see how 3054 // reference processing currently works in G1. 3055 _ref_processor_stw->enable_discovery(); 3056 3057 // We want to temporarily turn off discovery by the 3058 // CM ref processor, if necessary, and turn it back on 3059 // on again later if we do. Using a scoped 3060 // NoRefDiscovery object will do this. 3061 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3062 3063 policy()->record_collection_pause_start(sample_start_time_sec); 3064 3065 // Forget the current allocation region (we might even choose it to be part 3066 // of the collection set!). 3067 _allocator->release_mutator_alloc_region(); 3068 3069 calculate_collection_set(evacuation_info, target_pause_time_ms); 3070 3071 G1ParScanThreadStateSet per_thread_states(this, 3072 workers()->active_workers(), 3073 collection_set()->young_region_length(), 3074 collection_set()->optional_region_length()); 3075 pre_evacuate_collection_set(evacuation_info); 3076 3077 // Actually do the work... 3078 evacuate_initial_collection_set(&per_thread_states); 3079 3080 if (_collection_set.optional_region_length() != 0) { 3081 evacuate_optional_collection_set(&per_thread_states); 3082 } 3083 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3084 3085 start_new_collection_set(); 3086 3087 _survivor_evac_stats.adjust_desired_plab_sz(); 3088 _old_evac_stats.adjust_desired_plab_sz(); 3089 3090 if (should_start_conc_mark) { 3091 // We have to do this before we notify the CM threads that 3092 // they can start working to make sure that all the 3093 // appropriate initialization is done on the CM object. 3094 concurrent_mark()->post_initial_mark(); 3095 // Note that we don't actually trigger the CM thread at 3096 // this point. We do that later when we're sure that 3097 // the current thread has completed its logging output. 3098 } 3099 3100 allocate_dummy_regions(); 3101 3102 _allocator->init_mutator_alloc_region(); 3103 3104 expand_heap_after_young_collection(); 3105 3106 double sample_end_time_sec = os::elapsedTime(); 3107 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3108 size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards) + 3109 phase_times()->sum_thread_work_items(G1GCPhaseTimes::OptScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3110 policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3111 } 3112 3113 verify_after_young_collection(verify_type); 3114 3115 #ifdef TRACESPINNING 3116 ParallelTaskTerminator::print_termination_counts(); 3117 #endif 3118 3119 gc_epilogue(false); 3120 } 3121 3122 // Print the remainder of the GC log output. 3123 if (evacuation_failed()) { 3124 log_info(gc)("To-space exhausted"); 3125 } 3126 3127 policy()->print_phases(); 3128 heap_transition.print(); 3129 3130 _hrm->verify_optional(); 3131 _verifier->verify_region_sets_optional(); 3132 3133 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3134 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3135 3136 print_heap_after_gc(); 3137 print_heap_regions(); 3138 trace_heap_after_gc(_gc_tracer_stw); 3139 3140 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3141 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3142 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3143 // before any GC notifications are raised. 3144 g1mm()->update_sizes(); 3145 3146 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3147 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3148 _gc_timer_stw->register_gc_end(); 3149 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3150 } 3151 // It should now be safe to tell the concurrent mark thread to start 3152 // without its logging output interfering with the logging output 3153 // that came from the pause. 3154 3155 if (should_start_conc_mark) { 3156 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3157 // thread(s) could be running concurrently with us. Make sure that anything 3158 // after this point does not assume that we are the only GC thread running. 3159 // Note: of course, the actual marking work will not start until the safepoint 3160 // itself is released in SuspendibleThreadSet::desynchronize(). 3161 do_concurrent_mark(); 3162 } 3163 3164 return true; 3165 } 3166 3167 void G1CollectedHeap::remove_self_forwarding_pointers() { 3168 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3169 workers()->run_task(&rsfp_task); 3170 } 3171 3172 void G1CollectedHeap::restore_after_evac_failure() { 3173 double remove_self_forwards_start = os::elapsedTime(); 3174 3175 remove_self_forwarding_pointers(); 3176 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3177 _preserved_marks_set.restore(&task_executor); 3178 3179 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3180 } 3181 3182 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3183 if (!_evacuation_failed) { 3184 _evacuation_failed = true; 3185 } 3186 3187 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3188 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3189 } 3190 3191 bool G1ParEvacuateFollowersClosure::offer_termination() { 3192 EventGCPhaseParallel event; 3193 G1ParScanThreadState* const pss = par_scan_state(); 3194 start_term_time(); 3195 const bool res = terminator()->offer_termination(); 3196 end_term_time(); 3197 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3198 return res; 3199 } 3200 3201 void G1ParEvacuateFollowersClosure::do_void() { 3202 EventGCPhaseParallel event; 3203 G1ParScanThreadState* const pss = par_scan_state(); 3204 pss->trim_queue(); 3205 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3206 do { 3207 EventGCPhaseParallel event; 3208 pss->steal_and_trim_queue(queues()); 3209 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3210 } while (!offer_termination()); 3211 } 3212 3213 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3214 bool class_unloading_occurred) { 3215 uint num_workers = workers()->active_workers(); 3216 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3217 workers()->run_task(&unlink_task); 3218 } 3219 3220 // Clean string dedup data structures. 3221 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3222 // record the durations of the phases. Hence the almost-copy. 3223 class G1StringDedupCleaningTask : public AbstractGangTask { 3224 BoolObjectClosure* _is_alive; 3225 OopClosure* _keep_alive; 3226 G1GCPhaseTimes* _phase_times; 3227 3228 public: 3229 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3230 OopClosure* keep_alive, 3231 G1GCPhaseTimes* phase_times) : 3232 AbstractGangTask("Partial Cleaning Task"), 3233 _is_alive(is_alive), 3234 _keep_alive(keep_alive), 3235 _phase_times(phase_times) 3236 { 3237 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3238 StringDedup::gc_prologue(true); 3239 } 3240 3241 ~G1StringDedupCleaningTask() { 3242 StringDedup::gc_epilogue(); 3243 } 3244 3245 void work(uint worker_id) { 3246 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3247 { 3248 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3249 StringDedupQueue::unlink_or_oops_do(&cl); 3250 } 3251 { 3252 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3253 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3254 } 3255 } 3256 }; 3257 3258 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3259 OopClosure* keep_alive, 3260 G1GCPhaseTimes* phase_times) { 3261 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3262 workers()->run_task(&cl); 3263 } 3264 3265 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3266 private: 3267 G1DirtyCardQueueSet* _queue; 3268 G1CollectedHeap* _g1h; 3269 public: 3270 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3271 _queue(queue), _g1h(g1h) { } 3272 3273 virtual void work(uint worker_id) { 3274 G1GCPhaseTimes* p = _g1h->phase_times(); 3275 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3276 3277 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3278 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3279 3280 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3281 } 3282 }; 3283 3284 void G1CollectedHeap::redirty_logged_cards() { 3285 double redirty_logged_cards_start = os::elapsedTime(); 3286 3287 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3288 dirty_card_queue_set().reset_for_par_iteration(); 3289 workers()->run_task(&redirty_task); 3290 3291 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3292 dcq.merge_bufferlists(&dirty_card_queue_set()); 3293 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3294 3295 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3296 } 3297 3298 // Weak Reference Processing support 3299 3300 bool G1STWIsAliveClosure::do_object_b(oop p) { 3301 // An object is reachable if it is outside the collection set, 3302 // or is inside and copied. 3303 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3304 } 3305 3306 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3307 assert(obj != NULL, "must not be NULL"); 3308 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3309 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3310 // may falsely indicate that this is not the case here: however the collection set only 3311 // contains old regions when concurrent mark is not running. 3312 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3313 } 3314 3315 // Non Copying Keep Alive closure 3316 class G1KeepAliveClosure: public OopClosure { 3317 G1CollectedHeap*_g1h; 3318 public: 3319 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3320 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3321 void do_oop(oop* p) { 3322 oop obj = *p; 3323 assert(obj != NULL, "the caller should have filtered out NULL values"); 3324 3325 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3326 if (!region_attr.is_in_cset_or_humongous()) { 3327 return; 3328 } 3329 if (region_attr.is_in_cset()) { 3330 assert( obj->is_forwarded(), "invariant" ); 3331 *p = obj->forwardee(); 3332 } else { 3333 assert(!obj->is_forwarded(), "invariant" ); 3334 assert(region_attr.is_humongous(), 3335 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3336 _g1h->set_humongous_is_live(obj); 3337 } 3338 } 3339 }; 3340 3341 // Copying Keep Alive closure - can be called from both 3342 // serial and parallel code as long as different worker 3343 // threads utilize different G1ParScanThreadState instances 3344 // and different queues. 3345 3346 class G1CopyingKeepAliveClosure: public OopClosure { 3347 G1CollectedHeap* _g1h; 3348 G1ParScanThreadState* _par_scan_state; 3349 3350 public: 3351 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3352 G1ParScanThreadState* pss): 3353 _g1h(g1h), 3354 _par_scan_state(pss) 3355 {} 3356 3357 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3358 virtual void do_oop( oop* p) { do_oop_work(p); } 3359 3360 template <class T> void do_oop_work(T* p) { 3361 oop obj = RawAccess<>::oop_load(p); 3362 3363 if (_g1h->is_in_cset_or_humongous(obj)) { 3364 // If the referent object has been forwarded (either copied 3365 // to a new location or to itself in the event of an 3366 // evacuation failure) then we need to update the reference 3367 // field and, if both reference and referent are in the G1 3368 // heap, update the RSet for the referent. 3369 // 3370 // If the referent has not been forwarded then we have to keep 3371 // it alive by policy. Therefore we have copy the referent. 3372 // 3373 // When the queue is drained (after each phase of reference processing) 3374 // the object and it's followers will be copied, the reference field set 3375 // to point to the new location, and the RSet updated. 3376 _par_scan_state->push_on_queue(p); 3377 } 3378 } 3379 }; 3380 3381 // Serial drain queue closure. Called as the 'complete_gc' 3382 // closure for each discovered list in some of the 3383 // reference processing phases. 3384 3385 class G1STWDrainQueueClosure: public VoidClosure { 3386 protected: 3387 G1CollectedHeap* _g1h; 3388 G1ParScanThreadState* _par_scan_state; 3389 3390 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3391 3392 public: 3393 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3394 _g1h(g1h), 3395 _par_scan_state(pss) 3396 { } 3397 3398 void do_void() { 3399 G1ParScanThreadState* const pss = par_scan_state(); 3400 pss->trim_queue(); 3401 } 3402 }; 3403 3404 // Parallel Reference Processing closures 3405 3406 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3407 // processing during G1 evacuation pauses. 3408 3409 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3410 private: 3411 G1CollectedHeap* _g1h; 3412 G1ParScanThreadStateSet* _pss; 3413 RefToScanQueueSet* _queues; 3414 WorkGang* _workers; 3415 3416 public: 3417 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3418 G1ParScanThreadStateSet* per_thread_states, 3419 WorkGang* workers, 3420 RefToScanQueueSet *task_queues) : 3421 _g1h(g1h), 3422 _pss(per_thread_states), 3423 _queues(task_queues), 3424 _workers(workers) 3425 { 3426 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3427 } 3428 3429 // Executes the given task using concurrent marking worker threads. 3430 virtual void execute(ProcessTask& task, uint ergo_workers); 3431 }; 3432 3433 // Gang task for possibly parallel reference processing 3434 3435 class G1STWRefProcTaskProxy: public AbstractGangTask { 3436 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3437 ProcessTask& _proc_task; 3438 G1CollectedHeap* _g1h; 3439 G1ParScanThreadStateSet* _pss; 3440 RefToScanQueueSet* _task_queues; 3441 ParallelTaskTerminator* _terminator; 3442 3443 public: 3444 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3445 G1CollectedHeap* g1h, 3446 G1ParScanThreadStateSet* per_thread_states, 3447 RefToScanQueueSet *task_queues, 3448 ParallelTaskTerminator* terminator) : 3449 AbstractGangTask("Process reference objects in parallel"), 3450 _proc_task(proc_task), 3451 _g1h(g1h), 3452 _pss(per_thread_states), 3453 _task_queues(task_queues), 3454 _terminator(terminator) 3455 {} 3456 3457 virtual void work(uint worker_id) { 3458 // The reference processing task executed by a single worker. 3459 ResourceMark rm; 3460 HandleMark hm; 3461 3462 G1STWIsAliveClosure is_alive(_g1h); 3463 3464 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3465 pss->set_ref_discoverer(NULL); 3466 3467 // Keep alive closure. 3468 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3469 3470 // Complete GC closure 3471 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3472 3473 // Call the reference processing task's work routine. 3474 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3475 3476 // Note we cannot assert that the refs array is empty here as not all 3477 // of the processing tasks (specifically phase2 - pp2_work) execute 3478 // the complete_gc closure (which ordinarily would drain the queue) so 3479 // the queue may not be empty. 3480 } 3481 }; 3482 3483 // Driver routine for parallel reference processing. 3484 // Creates an instance of the ref processing gang 3485 // task and has the worker threads execute it. 3486 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3487 assert(_workers != NULL, "Need parallel worker threads."); 3488 3489 assert(_workers->active_workers() >= ergo_workers, 3490 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3491 ergo_workers, _workers->active_workers()); 3492 TaskTerminator terminator(ergo_workers, _queues); 3493 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3494 3495 _workers->run_task(&proc_task_proxy, ergo_workers); 3496 } 3497 3498 // End of weak reference support closures 3499 3500 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3501 double ref_proc_start = os::elapsedTime(); 3502 3503 ReferenceProcessor* rp = _ref_processor_stw; 3504 assert(rp->discovery_enabled(), "should have been enabled"); 3505 3506 // Closure to test whether a referent is alive. 3507 G1STWIsAliveClosure is_alive(this); 3508 3509 // Even when parallel reference processing is enabled, the processing 3510 // of JNI refs is serial and performed serially by the current thread 3511 // rather than by a worker. The following PSS will be used for processing 3512 // JNI refs. 3513 3514 // Use only a single queue for this PSS. 3515 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3516 pss->set_ref_discoverer(NULL); 3517 assert(pss->queue_is_empty(), "pre-condition"); 3518 3519 // Keep alive closure. 3520 G1CopyingKeepAliveClosure keep_alive(this, pss); 3521 3522 // Serial Complete GC closure 3523 G1STWDrainQueueClosure drain_queue(this, pss); 3524 3525 // Setup the soft refs policy... 3526 rp->setup_policy(false); 3527 3528 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3529 3530 ReferenceProcessorStats stats; 3531 if (!rp->processing_is_mt()) { 3532 // Serial reference processing... 3533 stats = rp->process_discovered_references(&is_alive, 3534 &keep_alive, 3535 &drain_queue, 3536 NULL, 3537 pt); 3538 } else { 3539 uint no_of_gc_workers = workers()->active_workers(); 3540 3541 // Parallel reference processing 3542 assert(no_of_gc_workers <= rp->max_num_queues(), 3543 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3544 no_of_gc_workers, rp->max_num_queues()); 3545 3546 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3547 stats = rp->process_discovered_references(&is_alive, 3548 &keep_alive, 3549 &drain_queue, 3550 &par_task_executor, 3551 pt); 3552 } 3553 3554 _gc_tracer_stw->report_gc_reference_stats(stats); 3555 3556 // We have completed copying any necessary live referent objects. 3557 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3558 3559 make_pending_list_reachable(); 3560 3561 assert(!rp->discovery_enabled(), "Postcondition"); 3562 rp->verify_no_references_recorded(); 3563 3564 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3565 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3566 } 3567 3568 void G1CollectedHeap::make_pending_list_reachable() { 3569 if (collector_state()->in_initial_mark_gc()) { 3570 oop pll_head = Universe::reference_pending_list(); 3571 if (pll_head != NULL) { 3572 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3573 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3574 } 3575 } 3576 } 3577 3578 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3579 double merge_pss_time_start = os::elapsedTime(); 3580 per_thread_states->flush(); 3581 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3582 } 3583 3584 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) { 3585 _expand_heap_after_alloc_failure = true; 3586 _evacuation_failed = false; 3587 3588 // Disable the hot card cache. 3589 _hot_card_cache->reset_hot_cache_claimed_index(); 3590 _hot_card_cache->set_use_cache(false); 3591 3592 // Initialize the GC alloc regions. 3593 _allocator->init_gc_alloc_regions(evacuation_info); 3594 3595 register_regions_with_region_attr(); 3596 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3597 3598 rem_set()->prepare_for_scan_rem_set(); 3599 _preserved_marks_set.assert_empty(); 3600 3601 #if COMPILER2_OR_JVMCI 3602 DerivedPointerTable::clear(); 3603 #endif 3604 3605 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3606 if (collector_state()->in_initial_mark_gc()) { 3607 concurrent_mark()->pre_initial_mark(); 3608 3609 double start_clear_claimed_marks = os::elapsedTime(); 3610 3611 ClassLoaderDataGraph::clear_claimed_marks(); 3612 3613 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3614 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3615 } 3616 3617 // Should G1EvacuationFailureALot be in effect for this GC? 3618 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3619 3620 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3621 } 3622 3623 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3624 protected: 3625 G1CollectedHeap* _g1h; 3626 G1ParScanThreadStateSet* _per_thread_states; 3627 RefToScanQueueSet* _task_queues; 3628 TaskTerminator _terminator; 3629 uint _num_workers; 3630 3631 void evacuate_live_objects(G1ParScanThreadState* pss, 3632 uint worker_id, 3633 G1GCPhaseTimes::GCParPhases objcopy_phase, 3634 G1GCPhaseTimes::GCParPhases termination_phase) { 3635 G1GCPhaseTimes* p = _g1h->phase_times(); 3636 3637 Ticks start = Ticks::now(); 3638 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase); 3639 cl.do_void(); 3640 3641 assert(pss->queue_is_empty(), "should be empty"); 3642 3643 Tickspan evac_time = (Ticks::now() - start); 3644 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3645 3646 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste); 3647 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste); 3648 3649 if (termination_phase == G1GCPhaseTimes::Termination) { 3650 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3651 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3652 } else { 3653 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3654 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3655 } 3656 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3657 } 3658 3659 virtual void start_work(uint worker_id) { } 3660 3661 virtual void end_work(uint worker_id) { } 3662 3663 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3664 3665 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3666 3667 public: 3668 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3669 AbstractGangTask(name), 3670 _g1h(G1CollectedHeap::heap()), 3671 _per_thread_states(per_thread_states), 3672 _task_queues(task_queues), 3673 _terminator(num_workers, _task_queues), 3674 _num_workers(num_workers) 3675 { } 3676 3677 void work(uint worker_id) { 3678 start_work(worker_id); 3679 3680 { 3681 ResourceMark rm; 3682 HandleMark hm; 3683 3684 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3685 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3686 3687 scan_roots(pss, worker_id); 3688 evacuate_live_objects(pss, worker_id); 3689 } 3690 3691 end_work(worker_id); 3692 } 3693 }; 3694 3695 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3696 G1RootProcessor* _root_processor; 3697 3698 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3699 _root_processor->evacuate_roots(pss, worker_id); 3700 _g1h->rem_set()->update_rem_set(pss, worker_id); 3701 _g1h->rem_set()->scan_rem_set(pss, worker_id, G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::CodeRoots); 3702 } 3703 3704 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3705 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3706 } 3707 3708 void start_work(uint worker_id) { 3709 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3710 } 3711 3712 void end_work(uint worker_id) { 3713 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3714 } 3715 3716 public: 3717 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3718 G1ParScanThreadStateSet* per_thread_states, 3719 RefToScanQueueSet* task_queues, 3720 G1RootProcessor* root_processor, 3721 uint num_workers) : 3722 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3723 _root_processor(root_processor) 3724 { } 3725 }; 3726 3727 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3728 Tickspan task_time; 3729 const uint num_workers = workers()->active_workers(); 3730 3731 Ticks start_processing = Ticks::now(); 3732 { 3733 G1RootProcessor root_processor(this, num_workers); 3734 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3735 task_time = run_task(&g1_par_task); 3736 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3737 // To extract its code root fixup time we measure total time of this scope and 3738 // subtract from the time the WorkGang task took. 3739 } 3740 Tickspan total_processing = Ticks::now() - start_processing; 3741 3742 G1GCPhaseTimes* p = phase_times(); 3743 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3744 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3745 } 3746 3747 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3748 3749 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3750 _g1h->rem_set()->scan_rem_set(pss, worker_id, G1GCPhaseTimes::OptScanRS, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptCodeRoots); 3751 } 3752 3753 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3754 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3755 } 3756 3757 public: 3758 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3759 RefToScanQueueSet* queues, 3760 uint num_workers) : 3761 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3762 } 3763 }; 3764 3765 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3766 class G1MarkScope : public MarkScope { }; 3767 3768 Tickspan task_time; 3769 3770 Ticks start_processing = Ticks::now(); 3771 { 3772 G1MarkScope code_mark_scope; 3773 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3774 task_time = run_task(&task); 3775 // See comment in evacuate_collection_set() for the reason of the scope. 3776 } 3777 Tickspan total_processing = Ticks::now() - start_processing; 3778 3779 G1GCPhaseTimes* p = phase_times(); 3780 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3781 } 3782 3783 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3784 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3785 3786 Ticks start = Ticks::now(); 3787 3788 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3789 3790 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3791 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3792 3793 if (time_left_ms < 0 || 3794 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3795 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3796 _collection_set.optional_region_length(), time_left_ms); 3797 break; 3798 } 3799 3800 evacuate_next_optional_regions(per_thread_states); 3801 } 3802 3803 _collection_set.abandon_optional_collection_set(per_thread_states); 3804 3805 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3806 } 3807 3808 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3809 // Also cleans the card table from temporary duplicate detection information used 3810 // during UpdateRS/ScanRS. 3811 rem_set()->cleanup_after_scan_rem_set(); 3812 3813 // Process any discovered reference objects - we have 3814 // to do this _before_ we retire the GC alloc regions 3815 // as we may have to copy some 'reachable' referent 3816 // objects (and their reachable sub-graphs) that were 3817 // not copied during the pause. 3818 process_discovered_references(per_thread_states); 3819 3820 G1STWIsAliveClosure is_alive(this); 3821 G1KeepAliveClosure keep_alive(this); 3822 3823 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3824 phase_times()->weak_phase_times()); 3825 3826 if (G1StringDedup::is_enabled()) { 3827 double string_dedup_time_ms = os::elapsedTime(); 3828 3829 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3830 3831 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3832 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3833 } 3834 3835 _allocator->release_gc_alloc_regions(evacuation_info); 3836 3837 if (evacuation_failed()) { 3838 restore_after_evac_failure(); 3839 3840 // Reset the G1EvacuationFailureALot counters and flags 3841 NOT_PRODUCT(reset_evacuation_should_fail();) 3842 3843 double recalculate_used_start = os::elapsedTime(); 3844 set_used(recalculate_used()); 3845 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3846 3847 if (_archive_allocator != NULL) { 3848 _archive_allocator->clear_used(); 3849 } 3850 for (uint i = 0; i < ParallelGCThreads; i++) { 3851 if (_evacuation_failed_info_array[i].has_failed()) { 3852 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3853 } 3854 } 3855 } else { 3856 // The "used" of the the collection set have already been subtracted 3857 // when they were freed. Add in the bytes evacuated. 3858 increase_used(policy()->bytes_copied_during_gc()); 3859 } 3860 3861 _preserved_marks_set.assert_empty(); 3862 3863 merge_per_thread_state_info(per_thread_states); 3864 3865 // Reset and re-enable the hot card cache. 3866 // Note the counts for the cards in the regions in the 3867 // collection set are reset when the collection set is freed. 3868 _hot_card_cache->reset_hot_cache(); 3869 _hot_card_cache->set_use_cache(true); 3870 3871 purge_code_root_memory(); 3872 3873 redirty_logged_cards(); 3874 3875 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3876 3877 eagerly_reclaim_humongous_regions(); 3878 3879 record_obj_copy_mem_stats(); 3880 3881 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3882 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3883 3884 #if COMPILER2_OR_JVMCI 3885 double start = os::elapsedTime(); 3886 DerivedPointerTable::update_pointers(); 3887 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3888 #endif 3889 policy()->print_age_table(); 3890 } 3891 3892 void G1CollectedHeap::record_obj_copy_mem_stats() { 3893 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3894 3895 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3896 create_g1_evac_summary(&_old_evac_stats)); 3897 } 3898 3899 void G1CollectedHeap::free_region(HeapRegion* hr, 3900 FreeRegionList* free_list, 3901 bool skip_remset, 3902 bool skip_hot_card_cache, 3903 bool locked) { 3904 assert(!hr->is_free(), "the region should not be free"); 3905 assert(!hr->is_empty(), "the region should not be empty"); 3906 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3907 assert(free_list != NULL, "pre-condition"); 3908 3909 if (G1VerifyBitmaps) { 3910 MemRegion mr(hr->bottom(), hr->end()); 3911 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3912 } 3913 3914 // Clear the card counts for this region. 3915 // Note: we only need to do this if the region is not young 3916 // (since we don't refine cards in young regions). 3917 if (!skip_hot_card_cache && !hr->is_young()) { 3918 _hot_card_cache->reset_card_counts(hr); 3919 } 3920 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3921 _policy->remset_tracker()->update_at_free(hr); 3922 free_list->add_ordered(hr); 3923 } 3924 3925 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3926 FreeRegionList* free_list) { 3927 assert(hr->is_humongous(), "this is only for humongous regions"); 3928 assert(free_list != NULL, "pre-condition"); 3929 hr->clear_humongous(); 3930 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3931 } 3932 3933 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3934 const uint humongous_regions_removed) { 3935 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3936 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3937 _old_set.bulk_remove(old_regions_removed); 3938 _humongous_set.bulk_remove(humongous_regions_removed); 3939 } 3940 3941 } 3942 3943 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3944 assert(list != NULL, "list can't be null"); 3945 if (!list->is_empty()) { 3946 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3947 _hrm->insert_list_into_free_list(list); 3948 } 3949 } 3950 3951 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3952 decrease_used(bytes); 3953 } 3954 3955 class G1FreeCollectionSetTask : public AbstractGangTask { 3956 private: 3957 3958 // Closure applied to all regions in the collection set to do work that needs to 3959 // be done serially in a single thread. 3960 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3961 private: 3962 G1EvacuationInfo* _evacuation_info; 3963 const size_t* _surviving_young_words; 3964 3965 // Bytes used in successfully evacuated regions before the evacuation. 3966 size_t _before_used_bytes; 3967 // Bytes used in unsucessfully evacuated regions before the evacuation 3968 size_t _after_used_bytes; 3969 3970 size_t _bytes_allocated_in_old_since_last_gc; 3971 3972 size_t _failure_used_words; 3973 size_t _failure_waste_words; 3974 3975 FreeRegionList _local_free_list; 3976 public: 3977 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3978 HeapRegionClosure(), 3979 _evacuation_info(evacuation_info), 3980 _surviving_young_words(surviving_young_words), 3981 _before_used_bytes(0), 3982 _after_used_bytes(0), 3983 _bytes_allocated_in_old_since_last_gc(0), 3984 _failure_used_words(0), 3985 _failure_waste_words(0), 3986 _local_free_list("Local Region List for CSet Freeing") { 3987 } 3988 3989 virtual bool do_heap_region(HeapRegion* r) { 3990 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3991 3992 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3993 g1h->clear_region_attr(r); 3994 3995 if (r->is_young()) { 3996 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 3997 "Young index %d is wrong for region %u of type %s with %u young regions", 3998 r->young_index_in_cset(), 3999 r->hrm_index(), 4000 r->get_type_str(), 4001 g1h->collection_set()->young_region_length()); 4002 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4003 r->record_surv_words_in_group(words_survived); 4004 } 4005 4006 if (!r->evacuation_failed()) { 4007 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4008 _before_used_bytes += r->used(); 4009 g1h->free_region(r, 4010 &_local_free_list, 4011 true, /* skip_remset */ 4012 true, /* skip_hot_card_cache */ 4013 true /* locked */); 4014 } else { 4015 r->uninstall_surv_rate_group(); 4016 r->set_young_index_in_cset(-1); 4017 r->set_evacuation_failed(false); 4018 // When moving a young gen region to old gen, we "allocate" that whole region 4019 // there. This is in addition to any already evacuated objects. Notify the 4020 // policy about that. 4021 // Old gen regions do not cause an additional allocation: both the objects 4022 // still in the region and the ones already moved are accounted for elsewhere. 4023 if (r->is_young()) { 4024 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4025 } 4026 // The region is now considered to be old. 4027 r->set_old(); 4028 // Do some allocation statistics accounting. Regions that failed evacuation 4029 // are always made old, so there is no need to update anything in the young 4030 // gen statistics, but we need to update old gen statistics. 4031 size_t used_words = r->marked_bytes() / HeapWordSize; 4032 4033 _failure_used_words += used_words; 4034 _failure_waste_words += HeapRegion::GrainWords - used_words; 4035 4036 g1h->old_set_add(r); 4037 _after_used_bytes += r->used(); 4038 } 4039 return false; 4040 } 4041 4042 void complete_work() { 4043 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4044 4045 _evacuation_info->set_regions_freed(_local_free_list.length()); 4046 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4047 4048 g1h->prepend_to_freelist(&_local_free_list); 4049 g1h->decrement_summary_bytes(_before_used_bytes); 4050 4051 G1Policy* policy = g1h->policy(); 4052 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4053 4054 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4055 } 4056 }; 4057 4058 G1CollectionSet* _collection_set; 4059 G1SerialFreeCollectionSetClosure _cl; 4060 const size_t* _surviving_young_words; 4061 4062 size_t _rs_lengths; 4063 4064 volatile jint _serial_work_claim; 4065 4066 struct WorkItem { 4067 uint region_idx; 4068 bool is_young; 4069 bool evacuation_failed; 4070 4071 WorkItem(HeapRegion* r) { 4072 region_idx = r->hrm_index(); 4073 is_young = r->is_young(); 4074 evacuation_failed = r->evacuation_failed(); 4075 } 4076 }; 4077 4078 volatile size_t _parallel_work_claim; 4079 size_t _num_work_items; 4080 WorkItem* _work_items; 4081 4082 void do_serial_work() { 4083 // Need to grab the lock to be allowed to modify the old region list. 4084 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4085 _collection_set->iterate(&_cl); 4086 } 4087 4088 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4089 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4090 4091 HeapRegion* r = g1h->region_at(region_idx); 4092 assert(!g1h->is_on_master_free_list(r), "sanity"); 4093 4094 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4095 4096 if (!is_young) { 4097 g1h->_hot_card_cache->reset_card_counts(r); 4098 } 4099 4100 if (!evacuation_failed) { 4101 r->rem_set()->clear_locked(); 4102 } 4103 } 4104 4105 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4106 private: 4107 size_t _cur_idx; 4108 WorkItem* _work_items; 4109 public: 4110 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4111 4112 virtual bool do_heap_region(HeapRegion* r) { 4113 _work_items[_cur_idx++] = WorkItem(r); 4114 return false; 4115 } 4116 }; 4117 4118 void prepare_work() { 4119 G1PrepareFreeCollectionSetClosure cl(_work_items); 4120 _collection_set->iterate(&cl); 4121 } 4122 4123 void complete_work() { 4124 _cl.complete_work(); 4125 4126 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4127 policy->record_max_rs_lengths(_rs_lengths); 4128 policy->cset_regions_freed(); 4129 } 4130 public: 4131 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4132 AbstractGangTask("G1 Free Collection Set"), 4133 _collection_set(collection_set), 4134 _cl(evacuation_info, surviving_young_words), 4135 _surviving_young_words(surviving_young_words), 4136 _rs_lengths(0), 4137 _serial_work_claim(0), 4138 _parallel_work_claim(0), 4139 _num_work_items(collection_set->region_length()), 4140 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4141 prepare_work(); 4142 } 4143 4144 ~G1FreeCollectionSetTask() { 4145 complete_work(); 4146 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4147 } 4148 4149 // Chunk size for work distribution. The chosen value has been determined experimentally 4150 // to be a good tradeoff between overhead and achievable parallelism. 4151 static uint chunk_size() { return 32; } 4152 4153 virtual void work(uint worker_id) { 4154 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4155 4156 // Claim serial work. 4157 if (_serial_work_claim == 0) { 4158 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4159 if (value == 0) { 4160 double serial_time = os::elapsedTime(); 4161 do_serial_work(); 4162 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4163 } 4164 } 4165 4166 // Start parallel work. 4167 double young_time = 0.0; 4168 bool has_young_time = false; 4169 double non_young_time = 0.0; 4170 bool has_non_young_time = false; 4171 4172 while (true) { 4173 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4174 size_t cur = end - chunk_size(); 4175 4176 if (cur >= _num_work_items) { 4177 break; 4178 } 4179 4180 EventGCPhaseParallel event; 4181 double start_time = os::elapsedTime(); 4182 4183 end = MIN2(end, _num_work_items); 4184 4185 for (; cur < end; cur++) { 4186 bool is_young = _work_items[cur].is_young; 4187 4188 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4189 4190 double end_time = os::elapsedTime(); 4191 double time_taken = end_time - start_time; 4192 if (is_young) { 4193 young_time += time_taken; 4194 has_young_time = true; 4195 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4196 } else { 4197 non_young_time += time_taken; 4198 has_non_young_time = true; 4199 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4200 } 4201 start_time = end_time; 4202 } 4203 } 4204 4205 if (has_young_time) { 4206 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4207 } 4208 if (has_non_young_time) { 4209 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4210 } 4211 } 4212 }; 4213 4214 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4215 _eden.clear(); 4216 4217 double free_cset_start_time = os::elapsedTime(); 4218 4219 { 4220 uint const num_regions = _collection_set.region_length(); 4221 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4222 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4223 4224 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4225 4226 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4227 cl.name(), num_workers, num_regions); 4228 workers()->run_task(&cl, num_workers); 4229 } 4230 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4231 4232 collection_set->clear(); 4233 } 4234 4235 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4236 private: 4237 FreeRegionList* _free_region_list; 4238 HeapRegionSet* _proxy_set; 4239 uint _humongous_objects_reclaimed; 4240 uint _humongous_regions_reclaimed; 4241 size_t _freed_bytes; 4242 public: 4243 4244 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4245 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4246 } 4247 4248 virtual bool do_heap_region(HeapRegion* r) { 4249 if (!r->is_starts_humongous()) { 4250 return false; 4251 } 4252 4253 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4254 4255 oop obj = (oop)r->bottom(); 4256 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4257 4258 // The following checks whether the humongous object is live are sufficient. 4259 // The main additional check (in addition to having a reference from the roots 4260 // or the young gen) is whether the humongous object has a remembered set entry. 4261 // 4262 // A humongous object cannot be live if there is no remembered set for it 4263 // because: 4264 // - there can be no references from within humongous starts regions referencing 4265 // the object because we never allocate other objects into them. 4266 // (I.e. there are no intra-region references that may be missed by the 4267 // remembered set) 4268 // - as soon there is a remembered set entry to the humongous starts region 4269 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4270 // until the end of a concurrent mark. 4271 // 4272 // It is not required to check whether the object has been found dead by marking 4273 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4274 // all objects allocated during that time are considered live. 4275 // SATB marking is even more conservative than the remembered set. 4276 // So if at this point in the collection there is no remembered set entry, 4277 // nobody has a reference to it. 4278 // At the start of collection we flush all refinement logs, and remembered sets 4279 // are completely up-to-date wrt to references to the humongous object. 4280 // 4281 // Other implementation considerations: 4282 // - never consider object arrays at this time because they would pose 4283 // considerable effort for cleaning up the the remembered sets. This is 4284 // required because stale remembered sets might reference locations that 4285 // are currently allocated into. 4286 uint region_idx = r->hrm_index(); 4287 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4288 !r->rem_set()->is_empty()) { 4289 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 4290 region_idx, 4291 (size_t)obj->size() * HeapWordSize, 4292 p2i(r->bottom()), 4293 r->rem_set()->occupied(), 4294 r->rem_set()->strong_code_roots_list_length(), 4295 next_bitmap->is_marked(r->bottom()), 4296 g1h->is_humongous_reclaim_candidate(region_idx), 4297 obj->is_typeArray() 4298 ); 4299 return false; 4300 } 4301 4302 guarantee(obj->is_typeArray(), 4303 "Only eagerly reclaiming type arrays is supported, but the object " 4304 PTR_FORMAT " is not.", p2i(r->bottom())); 4305 4306 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d", 4307 region_idx, 4308 (size_t)obj->size() * HeapWordSize, 4309 p2i(r->bottom()), 4310 r->rem_set()->occupied(), 4311 r->rem_set()->strong_code_roots_list_length(), 4312 next_bitmap->is_marked(r->bottom()), 4313 g1h->is_humongous_reclaim_candidate(region_idx), 4314 obj->is_typeArray() 4315 ); 4316 4317 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4318 cm->humongous_object_eagerly_reclaimed(r); 4319 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4320 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4321 region_idx, 4322 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4323 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4324 _humongous_objects_reclaimed++; 4325 do { 4326 HeapRegion* next = g1h->next_region_in_humongous(r); 4327 _freed_bytes += r->used(); 4328 r->set_containing_set(NULL); 4329 _humongous_regions_reclaimed++; 4330 g1h->free_humongous_region(r, _free_region_list); 4331 r = next; 4332 } while (r != NULL); 4333 4334 return false; 4335 } 4336 4337 uint humongous_objects_reclaimed() { 4338 return _humongous_objects_reclaimed; 4339 } 4340 4341 uint humongous_regions_reclaimed() { 4342 return _humongous_regions_reclaimed; 4343 } 4344 4345 size_t bytes_freed() const { 4346 return _freed_bytes; 4347 } 4348 }; 4349 4350 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4351 assert_at_safepoint_on_vm_thread(); 4352 4353 if (!G1EagerReclaimHumongousObjects || 4354 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4355 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4356 return; 4357 } 4358 4359 double start_time = os::elapsedTime(); 4360 4361 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4362 4363 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4364 heap_region_iterate(&cl); 4365 4366 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4367 4368 G1HRPrinter* hrp = hr_printer(); 4369 if (hrp->is_active()) { 4370 FreeRegionListIterator iter(&local_cleanup_list); 4371 while (iter.more_available()) { 4372 HeapRegion* hr = iter.get_next(); 4373 hrp->cleanup(hr); 4374 } 4375 } 4376 4377 prepend_to_freelist(&local_cleanup_list); 4378 decrement_summary_bytes(cl.bytes_freed()); 4379 4380 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4381 cl.humongous_objects_reclaimed()); 4382 } 4383 4384 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4385 public: 4386 virtual bool do_heap_region(HeapRegion* r) { 4387 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4388 G1CollectedHeap::heap()->clear_region_attr(r); 4389 r->set_young_index_in_cset(-1); 4390 return false; 4391 } 4392 }; 4393 4394 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4395 G1AbandonCollectionSetClosure cl; 4396 collection_set_iterate_all(&cl); 4397 4398 collection_set->clear(); 4399 collection_set->stop_incremental_building(); 4400 } 4401 4402 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4403 return _allocator->is_retained_old_region(hr); 4404 } 4405 4406 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4407 _eden.add(hr); 4408 _policy->set_region_eden(hr); 4409 } 4410 4411 #ifdef ASSERT 4412 4413 class NoYoungRegionsClosure: public HeapRegionClosure { 4414 private: 4415 bool _success; 4416 public: 4417 NoYoungRegionsClosure() : _success(true) { } 4418 bool do_heap_region(HeapRegion* r) { 4419 if (r->is_young()) { 4420 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4421 p2i(r->bottom()), p2i(r->end())); 4422 _success = false; 4423 } 4424 return false; 4425 } 4426 bool success() { return _success; } 4427 }; 4428 4429 bool G1CollectedHeap::check_young_list_empty() { 4430 bool ret = (young_regions_count() == 0); 4431 4432 NoYoungRegionsClosure closure; 4433 heap_region_iterate(&closure); 4434 ret = ret && closure.success(); 4435 4436 return ret; 4437 } 4438 4439 #endif // ASSERT 4440 4441 class TearDownRegionSetsClosure : public HeapRegionClosure { 4442 HeapRegionSet *_old_set; 4443 4444 public: 4445 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4446 4447 bool do_heap_region(HeapRegion* r) { 4448 if (r->is_old()) { 4449 _old_set->remove(r); 4450 } else if(r->is_young()) { 4451 r->uninstall_surv_rate_group(); 4452 } else { 4453 // We ignore free regions, we'll empty the free list afterwards. 4454 // We ignore humongous and archive regions, we're not tearing down these 4455 // sets. 4456 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4457 "it cannot be another type"); 4458 } 4459 return false; 4460 } 4461 4462 ~TearDownRegionSetsClosure() { 4463 assert(_old_set->is_empty(), "post-condition"); 4464 } 4465 }; 4466 4467 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4468 assert_at_safepoint_on_vm_thread(); 4469 4470 if (!free_list_only) { 4471 TearDownRegionSetsClosure cl(&_old_set); 4472 heap_region_iterate(&cl); 4473 4474 // Note that emptying the _young_list is postponed and instead done as 4475 // the first step when rebuilding the regions sets again. The reason for 4476 // this is that during a full GC string deduplication needs to know if 4477 // a collected region was young or old when the full GC was initiated. 4478 } 4479 _hrm->remove_all_free_regions(); 4480 } 4481 4482 void G1CollectedHeap::increase_used(size_t bytes) { 4483 _summary_bytes_used += bytes; 4484 } 4485 4486 void G1CollectedHeap::decrease_used(size_t bytes) { 4487 assert(_summary_bytes_used >= bytes, 4488 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4489 _summary_bytes_used, bytes); 4490 _summary_bytes_used -= bytes; 4491 } 4492 4493 void G1CollectedHeap::set_used(size_t bytes) { 4494 _summary_bytes_used = bytes; 4495 } 4496 4497 class RebuildRegionSetsClosure : public HeapRegionClosure { 4498 private: 4499 bool _free_list_only; 4500 4501 HeapRegionSet* _old_set; 4502 HeapRegionManager* _hrm; 4503 4504 size_t _total_used; 4505 4506 public: 4507 RebuildRegionSetsClosure(bool free_list_only, 4508 HeapRegionSet* old_set, 4509 HeapRegionManager* hrm) : 4510 _free_list_only(free_list_only), 4511 _old_set(old_set), _hrm(hrm), _total_used(0) { 4512 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4513 if (!free_list_only) { 4514 assert(_old_set->is_empty(), "pre-condition"); 4515 } 4516 } 4517 4518 bool do_heap_region(HeapRegion* r) { 4519 if (r->is_empty()) { 4520 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4521 // Add free regions to the free list 4522 r->set_free(); 4523 _hrm->insert_into_free_list(r); 4524 } else if (!_free_list_only) { 4525 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4526 4527 if (r->is_archive() || r->is_humongous()) { 4528 // We ignore archive and humongous regions. We left these sets unchanged. 4529 } else { 4530 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4531 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4532 r->move_to_old(); 4533 _old_set->add(r); 4534 } 4535 _total_used += r->used(); 4536 } 4537 4538 return false; 4539 } 4540 4541 size_t total_used() { 4542 return _total_used; 4543 } 4544 }; 4545 4546 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4547 assert_at_safepoint_on_vm_thread(); 4548 4549 if (!free_list_only) { 4550 _eden.clear(); 4551 _survivor.clear(); 4552 } 4553 4554 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4555 heap_region_iterate(&cl); 4556 4557 if (!free_list_only) { 4558 set_used(cl.total_used()); 4559 if (_archive_allocator != NULL) { 4560 _archive_allocator->clear_used(); 4561 } 4562 } 4563 assert_used_and_recalculate_used_equal(this); 4564 } 4565 4566 // Methods for the mutator alloc region 4567 4568 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4569 bool force) { 4570 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4571 bool should_allocate = policy()->should_allocate_mutator_region(); 4572 if (force || should_allocate) { 4573 HeapRegion* new_alloc_region = new_region(word_size, 4574 HeapRegionType::Eden, 4575 false /* do_expand */); 4576 if (new_alloc_region != NULL) { 4577 set_region_short_lived_locked(new_alloc_region); 4578 _hr_printer.alloc(new_alloc_region, !should_allocate); 4579 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4580 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4581 return new_alloc_region; 4582 } 4583 } 4584 return NULL; 4585 } 4586 4587 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4588 size_t allocated_bytes) { 4589 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4590 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4591 4592 collection_set()->add_eden_region(alloc_region); 4593 increase_used(allocated_bytes); 4594 _eden.add_used_bytes(allocated_bytes); 4595 _hr_printer.retire(alloc_region); 4596 4597 // We update the eden sizes here, when the region is retired, 4598 // instead of when it's allocated, since this is the point that its 4599 // used space has been recorded in _summary_bytes_used. 4600 g1mm()->update_eden_size(); 4601 } 4602 4603 // Methods for the GC alloc regions 4604 4605 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4606 if (dest.is_old()) { 4607 return true; 4608 } else { 4609 return survivor_regions_count() < policy()->max_survivor_regions(); 4610 } 4611 } 4612 4613 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) { 4614 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4615 4616 if (!has_more_regions(dest)) { 4617 return NULL; 4618 } 4619 4620 HeapRegionType type; 4621 if (dest.is_young()) { 4622 type = HeapRegionType::Survivor; 4623 } else { 4624 type = HeapRegionType::Old; 4625 } 4626 4627 HeapRegion* new_alloc_region = new_region(word_size, 4628 type, 4629 true /* do_expand */); 4630 4631 if (new_alloc_region != NULL) { 4632 if (type.is_survivor()) { 4633 new_alloc_region->set_survivor(); 4634 _survivor.add(new_alloc_region); 4635 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4636 } else { 4637 new_alloc_region->set_old(); 4638 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4639 } 4640 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4641 register_region_with_region_attr(new_alloc_region); 4642 _hr_printer.alloc(new_alloc_region); 4643 return new_alloc_region; 4644 } 4645 return NULL; 4646 } 4647 4648 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4649 size_t allocated_bytes, 4650 G1HeapRegionAttr dest) { 4651 policy()->record_bytes_copied_during_gc(allocated_bytes); 4652 if (dest.is_old()) { 4653 old_set_add(alloc_region); 4654 } else { 4655 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4656 _survivor.add_used_bytes(allocated_bytes); 4657 } 4658 4659 bool const during_im = collector_state()->in_initial_mark_gc(); 4660 if (during_im && allocated_bytes > 0) { 4661 _cm->root_regions()->add(alloc_region); 4662 } 4663 _hr_printer.retire(alloc_region); 4664 } 4665 4666 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4667 bool expanded = false; 4668 uint index = _hrm->find_highest_free(&expanded); 4669 4670 if (index != G1_NO_HRM_INDEX) { 4671 if (expanded) { 4672 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4673 HeapRegion::GrainWords * HeapWordSize); 4674 } 4675 _hrm->allocate_free_regions_starting_at(index, 1); 4676 return region_at(index); 4677 } 4678 return NULL; 4679 } 4680 4681 // Optimized nmethod scanning 4682 4683 class RegisterNMethodOopClosure: public OopClosure { 4684 G1CollectedHeap* _g1h; 4685 nmethod* _nm; 4686 4687 template <class T> void do_oop_work(T* p) { 4688 T heap_oop = RawAccess<>::oop_load(p); 4689 if (!CompressedOops::is_null(heap_oop)) { 4690 oop obj = CompressedOops::decode_not_null(heap_oop); 4691 HeapRegion* hr = _g1h->heap_region_containing(obj); 4692 assert(!hr->is_continues_humongous(), 4693 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4694 " starting at " HR_FORMAT, 4695 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4696 4697 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4698 hr->add_strong_code_root_locked(_nm); 4699 } 4700 } 4701 4702 public: 4703 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4704 _g1h(g1h), _nm(nm) {} 4705 4706 void do_oop(oop* p) { do_oop_work(p); } 4707 void do_oop(narrowOop* p) { do_oop_work(p); } 4708 }; 4709 4710 class UnregisterNMethodOopClosure: public OopClosure { 4711 G1CollectedHeap* _g1h; 4712 nmethod* _nm; 4713 4714 template <class T> void do_oop_work(T* p) { 4715 T heap_oop = RawAccess<>::oop_load(p); 4716 if (!CompressedOops::is_null(heap_oop)) { 4717 oop obj = CompressedOops::decode_not_null(heap_oop); 4718 HeapRegion* hr = _g1h->heap_region_containing(obj); 4719 assert(!hr->is_continues_humongous(), 4720 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4721 " starting at " HR_FORMAT, 4722 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4723 4724 hr->remove_strong_code_root(_nm); 4725 } 4726 } 4727 4728 public: 4729 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4730 _g1h(g1h), _nm(nm) {} 4731 4732 void do_oop(oop* p) { do_oop_work(p); } 4733 void do_oop(narrowOop* p) { do_oop_work(p); } 4734 }; 4735 4736 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4737 guarantee(nm != NULL, "sanity"); 4738 RegisterNMethodOopClosure reg_cl(this, nm); 4739 nm->oops_do(®_cl); 4740 } 4741 4742 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4743 guarantee(nm != NULL, "sanity"); 4744 UnregisterNMethodOopClosure reg_cl(this, nm); 4745 nm->oops_do(®_cl, true); 4746 } 4747 4748 void G1CollectedHeap::purge_code_root_memory() { 4749 double purge_start = os::elapsedTime(); 4750 G1CodeRootSet::purge(); 4751 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4752 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4753 } 4754 4755 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4756 G1CollectedHeap* _g1h; 4757 4758 public: 4759 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4760 _g1h(g1h) {} 4761 4762 void do_code_blob(CodeBlob* cb) { 4763 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4764 if (nm == NULL) { 4765 return; 4766 } 4767 4768 _g1h->register_nmethod(nm); 4769 } 4770 }; 4771 4772 void G1CollectedHeap::rebuild_strong_code_roots() { 4773 RebuildStrongCodeRootClosure blob_cl(this); 4774 CodeCache::blobs_do(&blob_cl); 4775 } 4776 4777 void G1CollectedHeap::initialize_serviceability() { 4778 _g1mm->initialize_serviceability(); 4779 } 4780 4781 MemoryUsage G1CollectedHeap::memory_usage() { 4782 return _g1mm->memory_usage(); 4783 } 4784 4785 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4786 return _g1mm->memory_managers(); 4787 } 4788 4789 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4790 return _g1mm->memory_pools(); 4791 }