1 /* 2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/g1Allocator.inline.hpp" 32 #include "gc/g1/g1Arguments.hpp" 33 #include "gc/g1/g1BarrierSet.hpp" 34 #include "gc/g1/g1CardTableEntryClosure.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectionSet.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 41 #include "gc/g1/g1DirtyCardQueue.hpp" 42 #include "gc/g1/g1EvacStats.inline.hpp" 43 #include "gc/g1/g1FullCollector.hpp" 44 #include "gc/g1/g1GCPhaseTimes.hpp" 45 #include "gc/g1/g1HeapSizingPolicy.hpp" 46 #include "gc/g1/g1HeapTransition.hpp" 47 #include "gc/g1/g1HeapVerifier.hpp" 48 #include "gc/g1/g1HotCardCache.hpp" 49 #include "gc/g1/g1MemoryPool.hpp" 50 #include "gc/g1/g1OopClosures.inline.hpp" 51 #include "gc/g1/g1ParallelCleaning.hpp" 52 #include "gc/g1/g1ParScanThreadState.inline.hpp" 53 #include "gc/g1/g1Policy.hpp" 54 #include "gc/g1/g1RedirtyCardsQueue.hpp" 55 #include "gc/g1/g1RegionToSpaceMapper.hpp" 56 #include "gc/g1/g1RemSet.hpp" 57 #include "gc/g1/g1RootClosures.hpp" 58 #include "gc/g1/g1RootProcessor.hpp" 59 #include "gc/g1/g1SATBMarkQueueSet.hpp" 60 #include "gc/g1/g1StringDedup.hpp" 61 #include "gc/g1/g1ThreadLocalData.hpp" 62 #include "gc/g1/g1Trace.hpp" 63 #include "gc/g1/g1YCTypes.hpp" 64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 65 #include "gc/g1/g1VMOperations.hpp" 66 #include "gc/g1/heapRegion.inline.hpp" 67 #include "gc/g1/heapRegionRemSet.hpp" 68 #include "gc/g1/heapRegionSet.inline.hpp" 69 #include "gc/shared/gcBehaviours.hpp" 70 #include "gc/shared/gcHeapSummary.hpp" 71 #include "gc/shared/gcId.hpp" 72 #include "gc/shared/gcLocker.hpp" 73 #include "gc/shared/gcTimer.hpp" 74 #include "gc/shared/gcTraceTime.inline.hpp" 75 #include "gc/shared/generationSpec.hpp" 76 #include "gc/shared/isGCActiveMark.hpp" 77 #include "gc/shared/locationPrinter.inline.hpp" 78 #include "gc/shared/oopStorageParState.hpp" 79 #include "gc/shared/preservedMarks.inline.hpp" 80 #include "gc/shared/suspendibleThreadSet.hpp" 81 #include "gc/shared/referenceProcessor.inline.hpp" 82 #include "gc/shared/taskqueue.inline.hpp" 83 #include "gc/shared/weakProcessor.inline.hpp" 84 #include "gc/shared/workerPolicy.hpp" 85 #include "logging/log.hpp" 86 #include "memory/allocation.hpp" 87 #include "memory/iterator.hpp" 88 #include "memory/resourceArea.hpp" 89 #include "memory/universe.hpp" 90 #include "oops/access.inline.hpp" 91 #include "oops/compressedOops.inline.hpp" 92 #include "oops/oop.inline.hpp" 93 #include "runtime/atomic.hpp" 94 #include "runtime/flags/flagSetting.hpp" 95 #include "runtime/handles.inline.hpp" 96 #include "runtime/init.hpp" 97 #include "runtime/orderAccess.hpp" 98 #include "runtime/threadSMR.hpp" 99 #include "runtime/vmThread.hpp" 100 #include "utilities/align.hpp" 101 #include "utilities/globalDefinitions.hpp" 102 #include "utilities/stack.inline.hpp" 103 104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 105 106 // INVARIANTS/NOTES 107 // 108 // All allocation activity covered by the G1CollectedHeap interface is 109 // serialized by acquiring the HeapLock. This happens in mem_allocate 110 // and allocate_new_tlab, which are the "entry" points to the 111 // allocation code from the rest of the JVM. (Note that this does not 112 // apply to TLAB allocation, which is not part of this interface: it 113 // is done by clients of this interface.) 114 115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 116 private: 117 size_t _num_dirtied; 118 G1CollectedHeap* _g1h; 119 G1CardTable* _g1_ct; 120 121 HeapRegion* region_for_card(CardValue* card_ptr) const { 122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 123 } 124 125 bool will_become_free(HeapRegion* hr) const { 126 // A region will be freed by free_collection_set if the region is in the 127 // collection set and has not had an evacuation failure. 128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 129 } 130 131 public: 132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 134 135 void do_card_ptr(CardValue* card_ptr, uint worker_i) { 136 HeapRegion* hr = region_for_card(card_ptr); 137 138 // Should only dirty cards in regions that won't be freed. 139 if (!will_become_free(hr)) { 140 *card_ptr = G1CardTable::dirty_card_val(); 141 _num_dirtied++; 142 } 143 } 144 145 size_t num_dirtied() const { return _num_dirtied; } 146 }; 147 148 149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 151 } 152 153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 154 // The from card cache is not the memory that is actually committed. So we cannot 155 // take advantage of the zero_filled parameter. 156 reset_from_card_cache(start_idx, num_regions); 157 } 158 159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 160 Ticks start = Ticks::now(); 161 workers()->run_task(task, workers()->active_workers()); 162 return Ticks::now() - start; 163 } 164 165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 166 MemRegion mr) { 167 return new HeapRegion(hrs_index, bot(), mr); 168 } 169 170 // Private methods. 171 172 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) { 173 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 174 "the only time we use this to allocate a humongous region is " 175 "when we are allocating a single humongous region"); 176 177 HeapRegion* res = _hrm->allocate_free_region(type); 178 179 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 180 // Currently, only attempts to allocate GC alloc regions set 181 // do_expand to true. So, we should only reach here during a 182 // safepoint. If this assumption changes we might have to 183 // reconsider the use of _expand_heap_after_alloc_failure. 184 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 185 186 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 187 word_size * HeapWordSize); 188 189 if (expand(word_size * HeapWordSize)) { 190 // Given that expand() succeeded in expanding the heap, and we 191 // always expand the heap by an amount aligned to the heap 192 // region size, the free list should in theory not be empty. 193 // In either case allocate_free_region() will check for NULL. 194 res = _hrm->allocate_free_region(type); 195 } else { 196 _expand_heap_after_alloc_failure = false; 197 } 198 } 199 return res; 200 } 201 202 HeapWord* 203 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 204 uint num_regions, 205 size_t word_size) { 206 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 207 assert(is_humongous(word_size), "word_size should be humongous"); 208 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 209 210 // Index of last region in the series. 211 uint last = first + num_regions - 1; 212 213 // We need to initialize the region(s) we just discovered. This is 214 // a bit tricky given that it can happen concurrently with 215 // refinement threads refining cards on these regions and 216 // potentially wanting to refine the BOT as they are scanning 217 // those cards (this can happen shortly after a cleanup; see CR 218 // 6991377). So we have to set up the region(s) carefully and in 219 // a specific order. 220 221 // The word size sum of all the regions we will allocate. 222 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 223 assert(word_size <= word_size_sum, "sanity"); 224 225 // This will be the "starts humongous" region. 226 HeapRegion* first_hr = region_at(first); 227 // The header of the new object will be placed at the bottom of 228 // the first region. 229 HeapWord* new_obj = first_hr->bottom(); 230 // This will be the new top of the new object. 231 HeapWord* obj_top = new_obj + word_size; 232 233 // First, we need to zero the header of the space that we will be 234 // allocating. When we update top further down, some refinement 235 // threads might try to scan the region. By zeroing the header we 236 // ensure that any thread that will try to scan the region will 237 // come across the zero klass word and bail out. 238 // 239 // NOTE: It would not have been correct to have used 240 // CollectedHeap::fill_with_object() and make the space look like 241 // an int array. The thread that is doing the allocation will 242 // later update the object header to a potentially different array 243 // type and, for a very short period of time, the klass and length 244 // fields will be inconsistent. This could cause a refinement 245 // thread to calculate the object size incorrectly. 246 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 247 248 // Next, pad out the unused tail of the last region with filler 249 // objects, for improved usage accounting. 250 // How many words we use for filler objects. 251 size_t word_fill_size = word_size_sum - word_size; 252 253 // How many words memory we "waste" which cannot hold a filler object. 254 size_t words_not_fillable = 0; 255 256 if (word_fill_size >= min_fill_size()) { 257 fill_with_objects(obj_top, word_fill_size); 258 } else if (word_fill_size > 0) { 259 // We have space to fill, but we cannot fit an object there. 260 words_not_fillable = word_fill_size; 261 word_fill_size = 0; 262 } 263 264 // We will set up the first region as "starts humongous". This 265 // will also update the BOT covering all the regions to reflect 266 // that there is a single object that starts at the bottom of the 267 // first region. 268 first_hr->set_starts_humongous(obj_top, word_fill_size); 269 _policy->remset_tracker()->update_at_allocate(first_hr); 270 // Then, if there are any, we will set up the "continues 271 // humongous" regions. 272 HeapRegion* hr = NULL; 273 for (uint i = first + 1; i <= last; ++i) { 274 hr = region_at(i); 275 hr->set_continues_humongous(first_hr); 276 _policy->remset_tracker()->update_at_allocate(hr); 277 } 278 279 // Up to this point no concurrent thread would have been able to 280 // do any scanning on any region in this series. All the top 281 // fields still point to bottom, so the intersection between 282 // [bottom,top] and [card_start,card_end] will be empty. Before we 283 // update the top fields, we'll do a storestore to make sure that 284 // no thread sees the update to top before the zeroing of the 285 // object header and the BOT initialization. 286 OrderAccess::storestore(); 287 288 // Now, we will update the top fields of the "continues humongous" 289 // regions except the last one. 290 for (uint i = first; i < last; ++i) { 291 hr = region_at(i); 292 hr->set_top(hr->end()); 293 } 294 295 hr = region_at(last); 296 // If we cannot fit a filler object, we must set top to the end 297 // of the humongous object, otherwise we cannot iterate the heap 298 // and the BOT will not be complete. 299 hr->set_top(hr->end() - words_not_fillable); 300 301 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 302 "obj_top should be in last region"); 303 304 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 305 306 assert(words_not_fillable == 0 || 307 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 308 "Miscalculation in humongous allocation"); 309 310 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 311 312 for (uint i = first; i <= last; ++i) { 313 hr = region_at(i); 314 _humongous_set.add(hr); 315 _hr_printer.alloc(hr); 316 } 317 318 return new_obj; 319 } 320 321 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 322 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 323 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 324 } 325 326 // If could fit into free regions w/o expansion, try. 327 // Otherwise, if can expand, do so. 328 // Otherwise, if using ex regions might help, try with ex given back. 329 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 330 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 331 332 _verifier->verify_region_sets_optional(); 333 334 uint first = G1_NO_HRM_INDEX; 335 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 336 337 if (obj_regions == 1) { 338 // Only one region to allocate, try to use a fast path by directly allocating 339 // from the free lists. Do not try to expand here, we will potentially do that 340 // later. 341 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 342 if (hr != NULL) { 343 first = hr->hrm_index(); 344 } 345 } else { 346 // Policy: Try only empty regions (i.e. already committed first). Maybe we 347 // are lucky enough to find some. 348 first = _hrm->find_contiguous_only_empty(obj_regions); 349 if (first != G1_NO_HRM_INDEX) { 350 _hrm->allocate_free_regions_starting_at(first, obj_regions); 351 } 352 } 353 354 if (first == G1_NO_HRM_INDEX) { 355 // Policy: We could not find enough regions for the humongous object in the 356 // free list. Look through the heap to find a mix of free and uncommitted regions. 357 // If so, try expansion. 358 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 359 if (first != G1_NO_HRM_INDEX) { 360 // We found something. Make sure these regions are committed, i.e. expand 361 // the heap. Alternatively we could do a defragmentation GC. 362 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 363 word_size * HeapWordSize); 364 365 _hrm->expand_at(first, obj_regions, workers()); 366 policy()->record_new_heap_size(num_regions()); 367 368 #ifdef ASSERT 369 for (uint i = first; i < first + obj_regions; ++i) { 370 HeapRegion* hr = region_at(i); 371 assert(hr->is_free(), "sanity"); 372 assert(hr->is_empty(), "sanity"); 373 assert(is_on_master_free_list(hr), "sanity"); 374 } 375 #endif 376 _hrm->allocate_free_regions_starting_at(first, obj_regions); 377 } else { 378 // Policy: Potentially trigger a defragmentation GC. 379 } 380 } 381 382 HeapWord* result = NULL; 383 if (first != G1_NO_HRM_INDEX) { 384 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 385 assert(result != NULL, "it should always return a valid result"); 386 387 // A successful humongous object allocation changes the used space 388 // information of the old generation so we need to recalculate the 389 // sizes and update the jstat counters here. 390 g1mm()->update_sizes(); 391 } 392 393 _verifier->verify_region_sets_optional(); 394 395 return result; 396 } 397 398 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 399 size_t requested_size, 400 size_t* actual_size) { 401 assert_heap_not_locked_and_not_at_safepoint(); 402 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 403 404 return attempt_allocation(min_size, requested_size, actual_size); 405 } 406 407 HeapWord* 408 G1CollectedHeap::mem_allocate(size_t word_size, 409 bool* gc_overhead_limit_was_exceeded) { 410 assert_heap_not_locked_and_not_at_safepoint(); 411 412 if (is_humongous(word_size)) { 413 return attempt_allocation_humongous(word_size); 414 } 415 size_t dummy = 0; 416 return attempt_allocation(word_size, word_size, &dummy); 417 } 418 419 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 420 ResourceMark rm; // For retrieving the thread names in log messages. 421 422 // Make sure you read the note in attempt_allocation_humongous(). 423 424 assert_heap_not_locked_and_not_at_safepoint(); 425 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 426 "be called for humongous allocation requests"); 427 428 // We should only get here after the first-level allocation attempt 429 // (attempt_allocation()) failed to allocate. 430 431 // We will loop until a) we manage to successfully perform the 432 // allocation or b) we successfully schedule a collection which 433 // fails to perform the allocation. b) is the only case when we'll 434 // return NULL. 435 HeapWord* result = NULL; 436 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 437 bool should_try_gc; 438 uint gc_count_before; 439 440 { 441 MutexLocker x(Heap_lock); 442 result = _allocator->attempt_allocation_locked(word_size); 443 if (result != NULL) { 444 return result; 445 } 446 447 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 448 // This is different to when only GCLocker::needs_gc() is set: try to avoid 449 // waiting because the GCLocker is active to not wait too long. 450 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 451 // No need for an ergo message here, can_expand_young_list() does this when 452 // it returns true. 453 result = _allocator->attempt_allocation_force(word_size); 454 if (result != NULL) { 455 return result; 456 } 457 } 458 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 459 // the GCLocker initiated GC has been performed and then retry. This includes 460 // the case when the GC Locker is not active but has not been performed. 461 should_try_gc = !GCLocker::needs_gc(); 462 // Read the GC count while still holding the Heap_lock. 463 gc_count_before = total_collections(); 464 } 465 466 if (should_try_gc) { 467 bool succeeded; 468 result = do_collection_pause(word_size, gc_count_before, &succeeded, 469 GCCause::_g1_inc_collection_pause); 470 if (result != NULL) { 471 assert(succeeded, "only way to get back a non-NULL result"); 472 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 473 Thread::current()->name(), p2i(result)); 474 return result; 475 } 476 477 if (succeeded) { 478 // We successfully scheduled a collection which failed to allocate. No 479 // point in trying to allocate further. We'll just return NULL. 480 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 481 SIZE_FORMAT " words", Thread::current()->name(), word_size); 482 return NULL; 483 } 484 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 485 Thread::current()->name(), word_size); 486 } else { 487 // Failed to schedule a collection. 488 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 489 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 490 SIZE_FORMAT " words", Thread::current()->name(), word_size); 491 return NULL; 492 } 493 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 494 // The GCLocker is either active or the GCLocker initiated 495 // GC has not yet been performed. Stall until it is and 496 // then retry the allocation. 497 GCLocker::stall_until_clear(); 498 gclocker_retry_count += 1; 499 } 500 501 // We can reach here if we were unsuccessful in scheduling a 502 // collection (because another thread beat us to it) or if we were 503 // stalled due to the GC locker. In either can we should retry the 504 // allocation attempt in case another thread successfully 505 // performed a collection and reclaimed enough space. We do the 506 // first attempt (without holding the Heap_lock) here and the 507 // follow-on attempt will be at the start of the next loop 508 // iteration (after taking the Heap_lock). 509 size_t dummy = 0; 510 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 511 if (result != NULL) { 512 return result; 513 } 514 515 // Give a warning if we seem to be looping forever. 516 if ((QueuedAllocationWarningCount > 0) && 517 (try_count % QueuedAllocationWarningCount == 0)) { 518 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 519 Thread::current()->name(), try_count, word_size); 520 } 521 } 522 523 ShouldNotReachHere(); 524 return NULL; 525 } 526 527 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 528 assert_at_safepoint_on_vm_thread(); 529 if (_archive_allocator == NULL) { 530 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 531 } 532 } 533 534 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 535 // Allocations in archive regions cannot be of a size that would be considered 536 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 537 // may be different at archive-restore time. 538 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 539 } 540 541 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 542 assert_at_safepoint_on_vm_thread(); 543 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 544 if (is_archive_alloc_too_large(word_size)) { 545 return NULL; 546 } 547 return _archive_allocator->archive_mem_allocate(word_size); 548 } 549 550 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 551 size_t end_alignment_in_bytes) { 552 assert_at_safepoint_on_vm_thread(); 553 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 554 555 // Call complete_archive to do the real work, filling in the MemRegion 556 // array with the archive regions. 557 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 558 delete _archive_allocator; 559 _archive_allocator = NULL; 560 } 561 562 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 563 assert(ranges != NULL, "MemRegion array NULL"); 564 assert(count != 0, "No MemRegions provided"); 565 MemRegion reserved = _hrm->reserved(); 566 for (size_t i = 0; i < count; i++) { 567 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 568 return false; 569 } 570 } 571 return true; 572 } 573 574 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 575 size_t count, 576 bool open) { 577 assert(!is_init_completed(), "Expect to be called at JVM init time"); 578 assert(ranges != NULL, "MemRegion array NULL"); 579 assert(count != 0, "No MemRegions provided"); 580 MutexLocker x(Heap_lock); 581 582 MemRegion reserved = _hrm->reserved(); 583 HeapWord* prev_last_addr = NULL; 584 HeapRegion* prev_last_region = NULL; 585 586 // Temporarily disable pretouching of heap pages. This interface is used 587 // when mmap'ing archived heap data in, so pre-touching is wasted. 588 FlagSetting fs(AlwaysPreTouch, false); 589 590 // Enable archive object checking used by G1MarkSweep. We have to let it know 591 // about each archive range, so that objects in those ranges aren't marked. 592 G1ArchiveAllocator::enable_archive_object_check(); 593 594 // For each specified MemRegion range, allocate the corresponding G1 595 // regions and mark them as archive regions. We expect the ranges 596 // in ascending starting address order, without overlap. 597 for (size_t i = 0; i < count; i++) { 598 MemRegion curr_range = ranges[i]; 599 HeapWord* start_address = curr_range.start(); 600 size_t word_size = curr_range.word_size(); 601 HeapWord* last_address = curr_range.last(); 602 size_t commits = 0; 603 604 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 605 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 606 p2i(start_address), p2i(last_address)); 607 guarantee(start_address > prev_last_addr, 608 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 609 p2i(start_address), p2i(prev_last_addr)); 610 prev_last_addr = last_address; 611 612 // Check for ranges that start in the same G1 region in which the previous 613 // range ended, and adjust the start address so we don't try to allocate 614 // the same region again. If the current range is entirely within that 615 // region, skip it, just adjusting the recorded top. 616 HeapRegion* start_region = _hrm->addr_to_region(start_address); 617 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 618 start_address = start_region->end(); 619 if (start_address > last_address) { 620 increase_used(word_size * HeapWordSize); 621 start_region->set_top(last_address + 1); 622 continue; 623 } 624 start_region->set_top(start_address); 625 curr_range = MemRegion(start_address, last_address + 1); 626 start_region = _hrm->addr_to_region(start_address); 627 } 628 629 // Perform the actual region allocation, exiting if it fails. 630 // Then note how much new space we have allocated. 631 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 632 return false; 633 } 634 increase_used(word_size * HeapWordSize); 635 if (commits != 0) { 636 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 637 HeapRegion::GrainWords * HeapWordSize * commits); 638 639 } 640 641 // Mark each G1 region touched by the range as archive, add it to 642 // the old set, and set top. 643 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 644 HeapRegion* last_region = _hrm->addr_to_region(last_address); 645 prev_last_region = last_region; 646 647 while (curr_region != NULL) { 648 assert(curr_region->is_empty() && !curr_region->is_pinned(), 649 "Region already in use (index %u)", curr_region->hrm_index()); 650 if (open) { 651 curr_region->set_open_archive(); 652 } else { 653 curr_region->set_closed_archive(); 654 } 655 _hr_printer.alloc(curr_region); 656 _archive_set.add(curr_region); 657 HeapWord* top; 658 HeapRegion* next_region; 659 if (curr_region != last_region) { 660 top = curr_region->end(); 661 next_region = _hrm->next_region_in_heap(curr_region); 662 } else { 663 top = last_address + 1; 664 next_region = NULL; 665 } 666 curr_region->set_top(top); 667 curr_region->set_first_dead(top); 668 curr_region->set_end_of_live(top); 669 curr_region = next_region; 670 } 671 672 // Notify mark-sweep of the archive 673 G1ArchiveAllocator::set_range_archive(curr_range, open); 674 } 675 return true; 676 } 677 678 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 679 assert(!is_init_completed(), "Expect to be called at JVM init time"); 680 assert(ranges != NULL, "MemRegion array NULL"); 681 assert(count != 0, "No MemRegions provided"); 682 MemRegion reserved = _hrm->reserved(); 683 HeapWord *prev_last_addr = NULL; 684 HeapRegion* prev_last_region = NULL; 685 686 // For each MemRegion, create filler objects, if needed, in the G1 regions 687 // that contain the address range. The address range actually within the 688 // MemRegion will not be modified. That is assumed to have been initialized 689 // elsewhere, probably via an mmap of archived heap data. 690 MutexLocker x(Heap_lock); 691 for (size_t i = 0; i < count; i++) { 692 HeapWord* start_address = ranges[i].start(); 693 HeapWord* last_address = ranges[i].last(); 694 695 assert(reserved.contains(start_address) && reserved.contains(last_address), 696 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 697 p2i(start_address), p2i(last_address)); 698 assert(start_address > prev_last_addr, 699 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 700 p2i(start_address), p2i(prev_last_addr)); 701 702 HeapRegion* start_region = _hrm->addr_to_region(start_address); 703 HeapRegion* last_region = _hrm->addr_to_region(last_address); 704 HeapWord* bottom_address = start_region->bottom(); 705 706 // Check for a range beginning in the same region in which the 707 // previous one ended. 708 if (start_region == prev_last_region) { 709 bottom_address = prev_last_addr + 1; 710 } 711 712 // Verify that the regions were all marked as archive regions by 713 // alloc_archive_regions. 714 HeapRegion* curr_region = start_region; 715 while (curr_region != NULL) { 716 guarantee(curr_region->is_archive(), 717 "Expected archive region at index %u", curr_region->hrm_index()); 718 if (curr_region != last_region) { 719 curr_region = _hrm->next_region_in_heap(curr_region); 720 } else { 721 curr_region = NULL; 722 } 723 } 724 725 prev_last_addr = last_address; 726 prev_last_region = last_region; 727 728 // Fill the memory below the allocated range with dummy object(s), 729 // if the region bottom does not match the range start, or if the previous 730 // range ended within the same G1 region, and there is a gap. 731 if (start_address != bottom_address) { 732 size_t fill_size = pointer_delta(start_address, bottom_address); 733 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 734 increase_used(fill_size * HeapWordSize); 735 } 736 } 737 } 738 739 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 740 size_t desired_word_size, 741 size_t* actual_word_size) { 742 assert_heap_not_locked_and_not_at_safepoint(); 743 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 744 "be called for humongous allocation requests"); 745 746 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 747 748 if (result == NULL) { 749 *actual_word_size = desired_word_size; 750 result = attempt_allocation_slow(desired_word_size); 751 } 752 753 assert_heap_not_locked(); 754 if (result != NULL) { 755 assert(*actual_word_size != 0, "Actual size must have been set here"); 756 dirty_young_block(result, *actual_word_size); 757 } else { 758 *actual_word_size = 0; 759 } 760 761 return result; 762 } 763 764 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 765 assert(!is_init_completed(), "Expect to be called at JVM init time"); 766 assert(ranges != NULL, "MemRegion array NULL"); 767 assert(count != 0, "No MemRegions provided"); 768 MemRegion reserved = _hrm->reserved(); 769 HeapWord* prev_last_addr = NULL; 770 HeapRegion* prev_last_region = NULL; 771 size_t size_used = 0; 772 size_t uncommitted_regions = 0; 773 774 // For each Memregion, free the G1 regions that constitute it, and 775 // notify mark-sweep that the range is no longer to be considered 'archive.' 776 MutexLocker x(Heap_lock); 777 for (size_t i = 0; i < count; i++) { 778 HeapWord* start_address = ranges[i].start(); 779 HeapWord* last_address = ranges[i].last(); 780 781 assert(reserved.contains(start_address) && reserved.contains(last_address), 782 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 783 p2i(start_address), p2i(last_address)); 784 assert(start_address > prev_last_addr, 785 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 786 p2i(start_address), p2i(prev_last_addr)); 787 size_used += ranges[i].byte_size(); 788 prev_last_addr = last_address; 789 790 HeapRegion* start_region = _hrm->addr_to_region(start_address); 791 HeapRegion* last_region = _hrm->addr_to_region(last_address); 792 793 // Check for ranges that start in the same G1 region in which the previous 794 // range ended, and adjust the start address so we don't try to free 795 // the same region again. If the current range is entirely within that 796 // region, skip it. 797 if (start_region == prev_last_region) { 798 start_address = start_region->end(); 799 if (start_address > last_address) { 800 continue; 801 } 802 start_region = _hrm->addr_to_region(start_address); 803 } 804 prev_last_region = last_region; 805 806 // After verifying that each region was marked as an archive region by 807 // alloc_archive_regions, set it free and empty and uncommit it. 808 HeapRegion* curr_region = start_region; 809 while (curr_region != NULL) { 810 guarantee(curr_region->is_archive(), 811 "Expected archive region at index %u", curr_region->hrm_index()); 812 uint curr_index = curr_region->hrm_index(); 813 _archive_set.remove(curr_region); 814 curr_region->set_free(); 815 curr_region->set_top(curr_region->bottom()); 816 if (curr_region != last_region) { 817 curr_region = _hrm->next_region_in_heap(curr_region); 818 } else { 819 curr_region = NULL; 820 } 821 _hrm->shrink_at(curr_index, 1); 822 uncommitted_regions++; 823 } 824 825 // Notify mark-sweep that this is no longer an archive range. 826 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 827 } 828 829 if (uncommitted_regions != 0) { 830 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 831 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 832 } 833 decrease_used(size_used); 834 } 835 836 oop G1CollectedHeap::materialize_archived_object(oop obj) { 837 assert(obj != NULL, "archived obj is NULL"); 838 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 839 840 // Loading an archived object makes it strongly reachable. If it is 841 // loaded during concurrent marking, it must be enqueued to the SATB 842 // queue, shading the previously white object gray. 843 G1BarrierSet::enqueue(obj); 844 845 return obj; 846 } 847 848 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 849 ResourceMark rm; // For retrieving the thread names in log messages. 850 851 // The structure of this method has a lot of similarities to 852 // attempt_allocation_slow(). The reason these two were not merged 853 // into a single one is that such a method would require several "if 854 // allocation is not humongous do this, otherwise do that" 855 // conditional paths which would obscure its flow. In fact, an early 856 // version of this code did use a unified method which was harder to 857 // follow and, as a result, it had subtle bugs that were hard to 858 // track down. So keeping these two methods separate allows each to 859 // be more readable. It will be good to keep these two in sync as 860 // much as possible. 861 862 assert_heap_not_locked_and_not_at_safepoint(); 863 assert(is_humongous(word_size), "attempt_allocation_humongous() " 864 "should only be called for humongous allocations"); 865 866 // Humongous objects can exhaust the heap quickly, so we should check if we 867 // need to start a marking cycle at each humongous object allocation. We do 868 // the check before we do the actual allocation. The reason for doing it 869 // before the allocation is that we avoid having to keep track of the newly 870 // allocated memory while we do a GC. 871 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 872 word_size)) { 873 collect(GCCause::_g1_humongous_allocation); 874 } 875 876 // We will loop until a) we manage to successfully perform the 877 // allocation or b) we successfully schedule a collection which 878 // fails to perform the allocation. b) is the only case when we'll 879 // return NULL. 880 HeapWord* result = NULL; 881 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 882 bool should_try_gc; 883 uint gc_count_before; 884 885 886 { 887 MutexLocker x(Heap_lock); 888 889 // Given that humongous objects are not allocated in young 890 // regions, we'll first try to do the allocation without doing a 891 // collection hoping that there's enough space in the heap. 892 result = humongous_obj_allocate(word_size); 893 if (result != NULL) { 894 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 895 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 896 return result; 897 } 898 899 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 900 // the GCLocker initiated GC has been performed and then retry. This includes 901 // the case when the GC Locker is not active but has not been performed. 902 should_try_gc = !GCLocker::needs_gc(); 903 // Read the GC count while still holding the Heap_lock. 904 gc_count_before = total_collections(); 905 } 906 907 if (should_try_gc) { 908 bool succeeded; 909 result = do_collection_pause(word_size, gc_count_before, &succeeded, 910 GCCause::_g1_humongous_allocation); 911 if (result != NULL) { 912 assert(succeeded, "only way to get back a non-NULL result"); 913 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 914 Thread::current()->name(), p2i(result)); 915 return result; 916 } 917 918 if (succeeded) { 919 // We successfully scheduled a collection which failed to allocate. No 920 // point in trying to allocate further. We'll just return NULL. 921 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 922 SIZE_FORMAT " words", Thread::current()->name(), word_size); 923 return NULL; 924 } 925 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 926 Thread::current()->name(), word_size); 927 } else { 928 // Failed to schedule a collection. 929 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 930 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 931 SIZE_FORMAT " words", Thread::current()->name(), word_size); 932 return NULL; 933 } 934 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 935 // The GCLocker is either active or the GCLocker initiated 936 // GC has not yet been performed. Stall until it is and 937 // then retry the allocation. 938 GCLocker::stall_until_clear(); 939 gclocker_retry_count += 1; 940 } 941 942 943 // We can reach here if we were unsuccessful in scheduling a 944 // collection (because another thread beat us to it) or if we were 945 // stalled due to the GC locker. In either can we should retry the 946 // allocation attempt in case another thread successfully 947 // performed a collection and reclaimed enough space. 948 // Humongous object allocation always needs a lock, so we wait for the retry 949 // in the next iteration of the loop, unlike for the regular iteration case. 950 // Give a warning if we seem to be looping forever. 951 952 if ((QueuedAllocationWarningCount > 0) && 953 (try_count % QueuedAllocationWarningCount == 0)) { 954 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 955 Thread::current()->name(), try_count, word_size); 956 } 957 } 958 959 ShouldNotReachHere(); 960 return NULL; 961 } 962 963 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 964 bool expect_null_mutator_alloc_region) { 965 assert_at_safepoint_on_vm_thread(); 966 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 967 "the current alloc region was unexpectedly found to be non-NULL"); 968 969 if (!is_humongous(word_size)) { 970 return _allocator->attempt_allocation_locked(word_size); 971 } else { 972 HeapWord* result = humongous_obj_allocate(word_size); 973 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 974 collector_state()->set_initiate_conc_mark_if_possible(true); 975 } 976 return result; 977 } 978 979 ShouldNotReachHere(); 980 } 981 982 class PostCompactionPrinterClosure: public HeapRegionClosure { 983 private: 984 G1HRPrinter* _hr_printer; 985 public: 986 bool do_heap_region(HeapRegion* hr) { 987 assert(!hr->is_young(), "not expecting to find young regions"); 988 _hr_printer->post_compaction(hr); 989 return false; 990 } 991 992 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 993 : _hr_printer(hr_printer) { } 994 }; 995 996 void G1CollectedHeap::print_hrm_post_compaction() { 997 if (_hr_printer.is_active()) { 998 PostCompactionPrinterClosure cl(hr_printer()); 999 heap_region_iterate(&cl); 1000 } 1001 } 1002 1003 void G1CollectedHeap::abort_concurrent_cycle() { 1004 // If we start the compaction before the CM threads finish 1005 // scanning the root regions we might trip them over as we'll 1006 // be moving objects / updating references. So let's wait until 1007 // they are done. By telling them to abort, they should complete 1008 // early. 1009 _cm->root_regions()->abort(); 1010 _cm->root_regions()->wait_until_scan_finished(); 1011 1012 // Disable discovery and empty the discovered lists 1013 // for the CM ref processor. 1014 _ref_processor_cm->disable_discovery(); 1015 _ref_processor_cm->abandon_partial_discovery(); 1016 _ref_processor_cm->verify_no_references_recorded(); 1017 1018 // Abandon current iterations of concurrent marking and concurrent 1019 // refinement, if any are in progress. 1020 concurrent_mark()->concurrent_cycle_abort(); 1021 } 1022 1023 void G1CollectedHeap::prepare_heap_for_full_collection() { 1024 // Make sure we'll choose a new allocation region afterwards. 1025 _allocator->release_mutator_alloc_region(); 1026 _allocator->abandon_gc_alloc_regions(); 1027 1028 // We may have added regions to the current incremental collection 1029 // set between the last GC or pause and now. We need to clear the 1030 // incremental collection set and then start rebuilding it afresh 1031 // after this full GC. 1032 abandon_collection_set(collection_set()); 1033 1034 tear_down_region_sets(false /* free_list_only */); 1035 1036 hrm()->prepare_for_full_collection_start(); 1037 } 1038 1039 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1040 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1041 assert_used_and_recalculate_used_equal(this); 1042 _verifier->verify_region_sets_optional(); 1043 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1044 _verifier->check_bitmaps("Full GC Start"); 1045 } 1046 1047 void G1CollectedHeap::prepare_heap_for_mutators() { 1048 hrm()->prepare_for_full_collection_end(); 1049 1050 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1051 ClassLoaderDataGraph::purge(); 1052 MetaspaceUtils::verify_metrics(); 1053 1054 // Prepare heap for normal collections. 1055 assert(num_free_regions() == 0, "we should not have added any free regions"); 1056 rebuild_region_sets(false /* free_list_only */); 1057 abort_refinement(); 1058 resize_heap_if_necessary(); 1059 1060 // Rebuild the strong code root lists for each region 1061 rebuild_strong_code_roots(); 1062 1063 // Purge code root memory 1064 purge_code_root_memory(); 1065 1066 // Start a new incremental collection set for the next pause 1067 start_new_collection_set(); 1068 1069 _allocator->init_mutator_alloc_region(); 1070 1071 // Post collection state updates. 1072 MetaspaceGC::compute_new_size(); 1073 } 1074 1075 void G1CollectedHeap::abort_refinement() { 1076 if (_hot_card_cache->use_cache()) { 1077 _hot_card_cache->reset_hot_cache(); 1078 } 1079 1080 // Discard all remembered set updates. 1081 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1082 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1083 "DCQS should be empty"); 1084 } 1085 1086 void G1CollectedHeap::verify_after_full_collection() { 1087 _hrm->verify_optional(); 1088 _verifier->verify_region_sets_optional(); 1089 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1090 // Clear the previous marking bitmap, if needed for bitmap verification. 1091 // Note we cannot do this when we clear the next marking bitmap in 1092 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1093 // objects marked during a full GC against the previous bitmap. 1094 // But we need to clear it before calling check_bitmaps below since 1095 // the full GC has compacted objects and updated TAMS but not updated 1096 // the prev bitmap. 1097 if (G1VerifyBitmaps) { 1098 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1099 _cm->clear_prev_bitmap(workers()); 1100 } 1101 // This call implicitly verifies that the next bitmap is clear after Full GC. 1102 _verifier->check_bitmaps("Full GC End"); 1103 1104 // At this point there should be no regions in the 1105 // entire heap tagged as young. 1106 assert(check_young_list_empty(), "young list should be empty at this point"); 1107 1108 // Note: since we've just done a full GC, concurrent 1109 // marking is no longer active. Therefore we need not 1110 // re-enable reference discovery for the CM ref processor. 1111 // That will be done at the start of the next marking cycle. 1112 // We also know that the STW processor should no longer 1113 // discover any new references. 1114 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1115 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1116 _ref_processor_stw->verify_no_references_recorded(); 1117 _ref_processor_cm->verify_no_references_recorded(); 1118 } 1119 1120 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1121 // Post collection logging. 1122 // We should do this after we potentially resize the heap so 1123 // that all the COMMIT / UNCOMMIT events are generated before 1124 // the compaction events. 1125 print_hrm_post_compaction(); 1126 heap_transition->print(); 1127 print_heap_after_gc(); 1128 print_heap_regions(); 1129 #ifdef TRACESPINNING 1130 ParallelTaskTerminator::print_termination_counts(); 1131 #endif 1132 } 1133 1134 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1135 bool clear_all_soft_refs) { 1136 assert_at_safepoint_on_vm_thread(); 1137 1138 if (GCLocker::check_active_before_gc()) { 1139 // Full GC was not completed. 1140 return false; 1141 } 1142 1143 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1144 soft_ref_policy()->should_clear_all_soft_refs(); 1145 1146 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1147 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1148 1149 collector.prepare_collection(); 1150 collector.collect(); 1151 collector.complete_collection(); 1152 1153 // Full collection was successfully completed. 1154 return true; 1155 } 1156 1157 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1158 // Currently, there is no facility in the do_full_collection(bool) API to notify 1159 // the caller that the collection did not succeed (e.g., because it was locked 1160 // out by the GC locker). So, right now, we'll ignore the return value. 1161 bool dummy = do_full_collection(true, /* explicit_gc */ 1162 clear_all_soft_refs); 1163 } 1164 1165 void G1CollectedHeap::resize_heap_if_necessary() { 1166 assert_at_safepoint_on_vm_thread(); 1167 1168 // Capacity, free and used after the GC counted as full regions to 1169 // include the waste in the following calculations. 1170 const size_t capacity_after_gc = capacity(); 1171 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1172 1173 // This is enforced in arguments.cpp. 1174 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1175 "otherwise the code below doesn't make sense"); 1176 1177 // We don't have floating point command-line arguments 1178 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1179 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1180 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1181 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1182 1183 // We have to be careful here as these two calculations can overflow 1184 // 32-bit size_t's. 1185 double used_after_gc_d = (double) used_after_gc; 1186 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1187 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1188 1189 // Let's make sure that they are both under the max heap size, which 1190 // by default will make them fit into a size_t. 1191 double desired_capacity_upper_bound = (double) MaxHeapSize; 1192 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1193 desired_capacity_upper_bound); 1194 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1195 desired_capacity_upper_bound); 1196 1197 // We can now safely turn them into size_t's. 1198 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1199 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1200 1201 // This assert only makes sense here, before we adjust them 1202 // with respect to the min and max heap size. 1203 assert(minimum_desired_capacity <= maximum_desired_capacity, 1204 "minimum_desired_capacity = " SIZE_FORMAT ", " 1205 "maximum_desired_capacity = " SIZE_FORMAT, 1206 minimum_desired_capacity, maximum_desired_capacity); 1207 1208 // Should not be greater than the heap max size. No need to adjust 1209 // it with respect to the heap min size as it's a lower bound (i.e., 1210 // we'll try to make the capacity larger than it, not smaller). 1211 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1212 // Should not be less than the heap min size. No need to adjust it 1213 // with respect to the heap max size as it's an upper bound (i.e., 1214 // we'll try to make the capacity smaller than it, not greater). 1215 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1216 1217 if (capacity_after_gc < minimum_desired_capacity) { 1218 // Don't expand unless it's significant 1219 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1220 1221 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1222 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1223 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1224 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1225 1226 expand(expand_bytes, _workers); 1227 1228 // No expansion, now see if we want to shrink 1229 } else if (capacity_after_gc > maximum_desired_capacity) { 1230 // Capacity too large, compute shrinking size 1231 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1232 1233 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1234 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1235 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1236 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1237 1238 shrink(shrink_bytes); 1239 } 1240 } 1241 1242 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1243 bool do_gc, 1244 bool clear_all_soft_refs, 1245 bool expect_null_mutator_alloc_region, 1246 bool* gc_succeeded) { 1247 *gc_succeeded = true; 1248 // Let's attempt the allocation first. 1249 HeapWord* result = 1250 attempt_allocation_at_safepoint(word_size, 1251 expect_null_mutator_alloc_region); 1252 if (result != NULL) { 1253 return result; 1254 } 1255 1256 // In a G1 heap, we're supposed to keep allocation from failing by 1257 // incremental pauses. Therefore, at least for now, we'll favor 1258 // expansion over collection. (This might change in the future if we can 1259 // do something smarter than full collection to satisfy a failed alloc.) 1260 result = expand_and_allocate(word_size); 1261 if (result != NULL) { 1262 return result; 1263 } 1264 1265 if (do_gc) { 1266 // Expansion didn't work, we'll try to do a Full GC. 1267 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1268 clear_all_soft_refs); 1269 } 1270 1271 return NULL; 1272 } 1273 1274 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1275 bool* succeeded) { 1276 assert_at_safepoint_on_vm_thread(); 1277 1278 // Attempts to allocate followed by Full GC. 1279 HeapWord* result = 1280 satisfy_failed_allocation_helper(word_size, 1281 true, /* do_gc */ 1282 false, /* clear_all_soft_refs */ 1283 false, /* expect_null_mutator_alloc_region */ 1284 succeeded); 1285 1286 if (result != NULL || !*succeeded) { 1287 return result; 1288 } 1289 1290 // Attempts to allocate followed by Full GC that will collect all soft references. 1291 result = satisfy_failed_allocation_helper(word_size, 1292 true, /* do_gc */ 1293 true, /* clear_all_soft_refs */ 1294 true, /* expect_null_mutator_alloc_region */ 1295 succeeded); 1296 1297 if (result != NULL || !*succeeded) { 1298 return result; 1299 } 1300 1301 // Attempts to allocate, no GC 1302 result = satisfy_failed_allocation_helper(word_size, 1303 false, /* do_gc */ 1304 false, /* clear_all_soft_refs */ 1305 true, /* expect_null_mutator_alloc_region */ 1306 succeeded); 1307 1308 if (result != NULL) { 1309 return result; 1310 } 1311 1312 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1313 "Flag should have been handled and cleared prior to this point"); 1314 1315 // What else? We might try synchronous finalization later. If the total 1316 // space available is large enough for the allocation, then a more 1317 // complete compaction phase than we've tried so far might be 1318 // appropriate. 1319 return NULL; 1320 } 1321 1322 // Attempting to expand the heap sufficiently 1323 // to support an allocation of the given "word_size". If 1324 // successful, perform the allocation and return the address of the 1325 // allocated block, or else "NULL". 1326 1327 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1328 assert_at_safepoint_on_vm_thread(); 1329 1330 _verifier->verify_region_sets_optional(); 1331 1332 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1333 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1334 word_size * HeapWordSize); 1335 1336 1337 if (expand(expand_bytes, _workers)) { 1338 _hrm->verify_optional(); 1339 _verifier->verify_region_sets_optional(); 1340 return attempt_allocation_at_safepoint(word_size, 1341 false /* expect_null_mutator_alloc_region */); 1342 } 1343 return NULL; 1344 } 1345 1346 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1347 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1348 aligned_expand_bytes = align_up(aligned_expand_bytes, 1349 HeapRegion::GrainBytes); 1350 1351 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1352 expand_bytes, aligned_expand_bytes); 1353 1354 if (is_maximal_no_gc()) { 1355 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1356 return false; 1357 } 1358 1359 double expand_heap_start_time_sec = os::elapsedTime(); 1360 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1361 assert(regions_to_expand > 0, "Must expand by at least one region"); 1362 1363 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1364 if (expand_time_ms != NULL) { 1365 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1366 } 1367 1368 if (expanded_by > 0) { 1369 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1370 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1371 policy()->record_new_heap_size(num_regions()); 1372 } else { 1373 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1374 1375 // The expansion of the virtual storage space was unsuccessful. 1376 // Let's see if it was because we ran out of swap. 1377 if (G1ExitOnExpansionFailure && 1378 _hrm->available() >= regions_to_expand) { 1379 // We had head room... 1380 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1381 } 1382 } 1383 return regions_to_expand > 0; 1384 } 1385 1386 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1387 size_t aligned_shrink_bytes = 1388 ReservedSpace::page_align_size_down(shrink_bytes); 1389 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1390 HeapRegion::GrainBytes); 1391 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1392 1393 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1394 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1395 1396 1397 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B", 1398 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1399 if (num_regions_removed > 0) { 1400 policy()->record_new_heap_size(num_regions()); 1401 } else { 1402 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1403 } 1404 } 1405 1406 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1407 _verifier->verify_region_sets_optional(); 1408 1409 // We should only reach here at the end of a Full GC or during Remark which 1410 // means we should not not be holding to any GC alloc regions. The method 1411 // below will make sure of that and do any remaining clean up. 1412 _allocator->abandon_gc_alloc_regions(); 1413 1414 // Instead of tearing down / rebuilding the free lists here, we 1415 // could instead use the remove_all_pending() method on free_list to 1416 // remove only the ones that we need to remove. 1417 tear_down_region_sets(true /* free_list_only */); 1418 shrink_helper(shrink_bytes); 1419 rebuild_region_sets(true /* free_list_only */); 1420 1421 _hrm->verify_optional(); 1422 _verifier->verify_region_sets_optional(); 1423 } 1424 1425 class OldRegionSetChecker : public HeapRegionSetChecker { 1426 public: 1427 void check_mt_safety() { 1428 // Master Old Set MT safety protocol: 1429 // (a) If we're at a safepoint, operations on the master old set 1430 // should be invoked: 1431 // - by the VM thread (which will serialize them), or 1432 // - by the GC workers while holding the FreeList_lock, if we're 1433 // at a safepoint for an evacuation pause (this lock is taken 1434 // anyway when an GC alloc region is retired so that a new one 1435 // is allocated from the free list), or 1436 // - by the GC workers while holding the OldSets_lock, if we're at a 1437 // safepoint for a cleanup pause. 1438 // (b) If we're not at a safepoint, operations on the master old set 1439 // should be invoked while holding the Heap_lock. 1440 1441 if (SafepointSynchronize::is_at_safepoint()) { 1442 guarantee(Thread::current()->is_VM_thread() || 1443 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1444 "master old set MT safety protocol at a safepoint"); 1445 } else { 1446 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1447 } 1448 } 1449 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1450 const char* get_description() { return "Old Regions"; } 1451 }; 1452 1453 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1454 public: 1455 void check_mt_safety() { 1456 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1457 "May only change archive regions during initialization or safepoint."); 1458 } 1459 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1460 const char* get_description() { return "Archive Regions"; } 1461 }; 1462 1463 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1464 public: 1465 void check_mt_safety() { 1466 // Humongous Set MT safety protocol: 1467 // (a) If we're at a safepoint, operations on the master humongous 1468 // set should be invoked by either the VM thread (which will 1469 // serialize them) or by the GC workers while holding the 1470 // OldSets_lock. 1471 // (b) If we're not at a safepoint, operations on the master 1472 // humongous set should be invoked while holding the Heap_lock. 1473 1474 if (SafepointSynchronize::is_at_safepoint()) { 1475 guarantee(Thread::current()->is_VM_thread() || 1476 OldSets_lock->owned_by_self(), 1477 "master humongous set MT safety protocol at a safepoint"); 1478 } else { 1479 guarantee(Heap_lock->owned_by_self(), 1480 "master humongous set MT safety protocol outside a safepoint"); 1481 } 1482 } 1483 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1484 const char* get_description() { return "Humongous Regions"; } 1485 }; 1486 1487 G1CollectedHeap::G1CollectedHeap() : 1488 CollectedHeap(), 1489 _young_gen_sampling_thread(NULL), 1490 _workers(NULL), 1491 _card_table(NULL), 1492 _soft_ref_policy(), 1493 _old_set("Old Region Set", new OldRegionSetChecker()), 1494 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1495 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1496 _bot(NULL), 1497 _listener(), 1498 _hrm(NULL), 1499 _allocator(NULL), 1500 _verifier(NULL), 1501 _summary_bytes_used(0), 1502 _archive_allocator(NULL), 1503 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1504 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1505 _expand_heap_after_alloc_failure(true), 1506 _g1mm(NULL), 1507 _humongous_reclaim_candidates(), 1508 _has_humongous_reclaim_candidates(false), 1509 _hr_printer(), 1510 _collector_state(), 1511 _old_marking_cycles_started(0), 1512 _old_marking_cycles_completed(0), 1513 _eden(), 1514 _survivor(), 1515 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1516 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1517 _policy(G1Policy::create_policy(_gc_timer_stw)), 1518 _heap_sizing_policy(NULL), 1519 _collection_set(this, _policy), 1520 _hot_card_cache(NULL), 1521 _rem_set(NULL), 1522 _cm(NULL), 1523 _cm_thread(NULL), 1524 _cr(NULL), 1525 _task_queues(NULL), 1526 _evacuation_failed(false), 1527 _evacuation_failed_info_array(NULL), 1528 _preserved_marks_set(true /* in_c_heap */), 1529 #ifndef PRODUCT 1530 _evacuation_failure_alot_for_current_gc(false), 1531 _evacuation_failure_alot_gc_number(0), 1532 _evacuation_failure_alot_count(0), 1533 #endif 1534 _ref_processor_stw(NULL), 1535 _is_alive_closure_stw(this), 1536 _is_subject_to_discovery_stw(this), 1537 _ref_processor_cm(NULL), 1538 _is_alive_closure_cm(this), 1539 _is_subject_to_discovery_cm(this), 1540 _region_attr() { 1541 1542 _verifier = new G1HeapVerifier(this); 1543 1544 _allocator = new G1Allocator(this); 1545 1546 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1547 1548 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1549 1550 // Override the default _filler_array_max_size so that no humongous filler 1551 // objects are created. 1552 _filler_array_max_size = _humongous_object_threshold_in_words; 1553 1554 uint n_queues = ParallelGCThreads; 1555 _task_queues = new RefToScanQueueSet(n_queues); 1556 1557 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1558 1559 for (uint i = 0; i < n_queues; i++) { 1560 RefToScanQueue* q = new RefToScanQueue(); 1561 q->initialize(); 1562 _task_queues->register_queue(i, q); 1563 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1564 } 1565 1566 // Initialize the G1EvacuationFailureALot counters and flags. 1567 NOT_PRODUCT(reset_evacuation_should_fail();) 1568 _gc_tracer_stw->initialize(); 1569 1570 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1571 } 1572 1573 static size_t actual_reserved_page_size(ReservedSpace rs) { 1574 size_t page_size = os::vm_page_size(); 1575 if (UseLargePages) { 1576 // There are two ways to manage large page memory. 1577 // 1. OS supports committing large page memory. 1578 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1579 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1580 // we reserved memory without large page. 1581 if (os::can_commit_large_page_memory() || rs.special()) { 1582 // An alignment at ReservedSpace comes from preferred page size or 1583 // heap alignment, and if the alignment came from heap alignment, it could be 1584 // larger than large pages size. So need to cap with the large page size. 1585 page_size = MIN2(rs.alignment(), os::large_page_size()); 1586 } 1587 } 1588 1589 return page_size; 1590 } 1591 1592 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1593 size_t size, 1594 size_t translation_factor) { 1595 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1596 // Allocate a new reserved space, preferring to use large pages. 1597 ReservedSpace rs(size, preferred_page_size); 1598 size_t page_size = actual_reserved_page_size(rs); 1599 G1RegionToSpaceMapper* result = 1600 G1RegionToSpaceMapper::create_mapper(rs, 1601 size, 1602 page_size, 1603 HeapRegion::GrainBytes, 1604 translation_factor, 1605 mtGC); 1606 1607 os::trace_page_sizes_for_requested_size(description, 1608 size, 1609 preferred_page_size, 1610 page_size, 1611 rs.base(), 1612 rs.size()); 1613 1614 return result; 1615 } 1616 1617 jint G1CollectedHeap::initialize_concurrent_refinement() { 1618 jint ecode = JNI_OK; 1619 _cr = G1ConcurrentRefine::create(&ecode); 1620 return ecode; 1621 } 1622 1623 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1624 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1625 if (_young_gen_sampling_thread->osthread() == NULL) { 1626 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1627 return JNI_ENOMEM; 1628 } 1629 return JNI_OK; 1630 } 1631 1632 jint G1CollectedHeap::initialize() { 1633 os::enable_vtime(); 1634 1635 // Necessary to satisfy locking discipline assertions. 1636 1637 MutexLocker x(Heap_lock); 1638 1639 // While there are no constraints in the GC code that HeapWordSize 1640 // be any particular value, there are multiple other areas in the 1641 // system which believe this to be true (e.g. oop->object_size in some 1642 // cases incorrectly returns the size in wordSize units rather than 1643 // HeapWordSize). 1644 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1645 1646 size_t init_byte_size = InitialHeapSize; 1647 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1648 1649 // Ensure that the sizes are properly aligned. 1650 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1651 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1652 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1653 1654 // Reserve the maximum. 1655 1656 // When compressed oops are enabled, the preferred heap base 1657 // is calculated by subtracting the requested size from the 1658 // 32Gb boundary and using the result as the base address for 1659 // heap reservation. If the requested size is not aligned to 1660 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1661 // into the ReservedHeapSpace constructor) then the actual 1662 // base of the reserved heap may end up differing from the 1663 // address that was requested (i.e. the preferred heap base). 1664 // If this happens then we could end up using a non-optimal 1665 // compressed oops mode. 1666 1667 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1668 HeapAlignment); 1669 1670 initialize_reserved_region(heap_rs); 1671 1672 // Create the barrier set for the entire reserved region. 1673 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1674 ct->initialize(); 1675 G1BarrierSet* bs = new G1BarrierSet(ct); 1676 bs->initialize(); 1677 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1678 BarrierSet::set_barrier_set(bs); 1679 _card_table = ct; 1680 1681 G1BarrierSet::satb_mark_queue_set().initialize(this, 1682 &bs->satb_mark_queue_buffer_allocator(), 1683 G1SATBProcessCompletedThreshold, 1684 G1SATBBufferEnqueueingThresholdPercent); 1685 1686 // process_cards_threshold and max_cards are updated 1687 // later, based on the concurrent refinement object. 1688 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1689 &bs->dirty_card_queue_buffer_allocator()); 1690 1691 // Create the hot card cache. 1692 _hot_card_cache = new G1HotCardCache(this); 1693 1694 // Carve out the G1 part of the heap. 1695 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1696 size_t page_size = actual_reserved_page_size(heap_rs); 1697 G1RegionToSpaceMapper* heap_storage = 1698 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1699 g1_rs.size(), 1700 page_size, 1701 HeapRegion::GrainBytes, 1702 1, 1703 mtJavaHeap); 1704 if(heap_storage == NULL) { 1705 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1706 return JNI_ERR; 1707 } 1708 1709 os::trace_page_sizes("Heap", 1710 MinHeapSize, 1711 reserved_byte_size, 1712 page_size, 1713 heap_rs.base(), 1714 heap_rs.size()); 1715 heap_storage->set_mapping_changed_listener(&_listener); 1716 1717 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1718 G1RegionToSpaceMapper* bot_storage = 1719 create_aux_memory_mapper("Block Offset Table", 1720 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1721 G1BlockOffsetTable::heap_map_factor()); 1722 1723 G1RegionToSpaceMapper* cardtable_storage = 1724 create_aux_memory_mapper("Card Table", 1725 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1726 G1CardTable::heap_map_factor()); 1727 1728 G1RegionToSpaceMapper* card_counts_storage = 1729 create_aux_memory_mapper("Card Counts Table", 1730 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1731 G1CardCounts::heap_map_factor()); 1732 1733 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1734 G1RegionToSpaceMapper* prev_bitmap_storage = 1735 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1736 G1RegionToSpaceMapper* next_bitmap_storage = 1737 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1738 1739 _hrm = HeapRegionManager::create_manager(this); 1740 1741 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1742 _card_table->initialize(cardtable_storage); 1743 1744 // Do later initialization work for concurrent refinement. 1745 _hot_card_cache->initialize(card_counts_storage); 1746 1747 // 6843694 - ensure that the maximum region index can fit 1748 // in the remembered set structures. 1749 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1750 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1751 1752 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1753 // start within the first card. 1754 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1755 // Also create a G1 rem set. 1756 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1757 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1758 1759 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1760 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1761 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1762 "too many cards per region"); 1763 1764 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1765 1766 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1767 1768 { 1769 HeapWord* start = _hrm->reserved().start(); 1770 HeapWord* end = _hrm->reserved().end(); 1771 size_t granularity = HeapRegion::GrainBytes; 1772 1773 _region_attr.initialize(start, end, granularity); 1774 _humongous_reclaim_candidates.initialize(start, end, granularity); 1775 } 1776 1777 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1778 true /* are_GC_task_threads */, 1779 false /* are_ConcurrentGC_threads */); 1780 if (_workers == NULL) { 1781 return JNI_ENOMEM; 1782 } 1783 _workers->initialize_workers(); 1784 1785 // Create the G1ConcurrentMark data structure and thread. 1786 // (Must do this late, so that "max_regions" is defined.) 1787 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1788 if (_cm == NULL || !_cm->completed_initialization()) { 1789 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1790 return JNI_ENOMEM; 1791 } 1792 _cm_thread = _cm->cm_thread(); 1793 1794 // Now expand into the initial heap size. 1795 if (!expand(init_byte_size, _workers)) { 1796 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1797 return JNI_ENOMEM; 1798 } 1799 1800 // Perform any initialization actions delegated to the policy. 1801 policy()->init(this, &_collection_set); 1802 1803 jint ecode = initialize_concurrent_refinement(); 1804 if (ecode != JNI_OK) { 1805 return ecode; 1806 } 1807 1808 ecode = initialize_young_gen_sampling_thread(); 1809 if (ecode != JNI_OK) { 1810 return ecode; 1811 } 1812 1813 { 1814 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1815 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1816 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1817 } 1818 1819 // Here we allocate the dummy HeapRegion that is required by the 1820 // G1AllocRegion class. 1821 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1822 1823 // We'll re-use the same region whether the alloc region will 1824 // require BOT updates or not and, if it doesn't, then a non-young 1825 // region will complain that it cannot support allocations without 1826 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1827 dummy_region->set_eden(); 1828 // Make sure it's full. 1829 dummy_region->set_top(dummy_region->end()); 1830 G1AllocRegion::setup(this, dummy_region); 1831 1832 _allocator->init_mutator_alloc_region(); 1833 1834 // Do create of the monitoring and management support so that 1835 // values in the heap have been properly initialized. 1836 _g1mm = new G1MonitoringSupport(this); 1837 1838 G1StringDedup::initialize(); 1839 1840 _preserved_marks_set.init(ParallelGCThreads); 1841 1842 _collection_set.initialize(max_regions()); 1843 1844 return JNI_OK; 1845 } 1846 1847 void G1CollectedHeap::stop() { 1848 // Stop all concurrent threads. We do this to make sure these threads 1849 // do not continue to execute and access resources (e.g. logging) 1850 // that are destroyed during shutdown. 1851 _cr->stop(); 1852 _young_gen_sampling_thread->stop(); 1853 _cm_thread->stop(); 1854 if (G1StringDedup::is_enabled()) { 1855 G1StringDedup::stop(); 1856 } 1857 } 1858 1859 void G1CollectedHeap::safepoint_synchronize_begin() { 1860 SuspendibleThreadSet::synchronize(); 1861 } 1862 1863 void G1CollectedHeap::safepoint_synchronize_end() { 1864 SuspendibleThreadSet::desynchronize(); 1865 } 1866 1867 void G1CollectedHeap::post_initialize() { 1868 CollectedHeap::post_initialize(); 1869 ref_processing_init(); 1870 } 1871 1872 void G1CollectedHeap::ref_processing_init() { 1873 // Reference processing in G1 currently works as follows: 1874 // 1875 // * There are two reference processor instances. One is 1876 // used to record and process discovered references 1877 // during concurrent marking; the other is used to 1878 // record and process references during STW pauses 1879 // (both full and incremental). 1880 // * Both ref processors need to 'span' the entire heap as 1881 // the regions in the collection set may be dotted around. 1882 // 1883 // * For the concurrent marking ref processor: 1884 // * Reference discovery is enabled at initial marking. 1885 // * Reference discovery is disabled and the discovered 1886 // references processed etc during remarking. 1887 // * Reference discovery is MT (see below). 1888 // * Reference discovery requires a barrier (see below). 1889 // * Reference processing may or may not be MT 1890 // (depending on the value of ParallelRefProcEnabled 1891 // and ParallelGCThreads). 1892 // * A full GC disables reference discovery by the CM 1893 // ref processor and abandons any entries on it's 1894 // discovered lists. 1895 // 1896 // * For the STW processor: 1897 // * Non MT discovery is enabled at the start of a full GC. 1898 // * Processing and enqueueing during a full GC is non-MT. 1899 // * During a full GC, references are processed after marking. 1900 // 1901 // * Discovery (may or may not be MT) is enabled at the start 1902 // of an incremental evacuation pause. 1903 // * References are processed near the end of a STW evacuation pause. 1904 // * For both types of GC: 1905 // * Discovery is atomic - i.e. not concurrent. 1906 // * Reference discovery will not need a barrier. 1907 1908 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1909 1910 // Concurrent Mark ref processor 1911 _ref_processor_cm = 1912 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1913 mt_processing, // mt processing 1914 ParallelGCThreads, // degree of mt processing 1915 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1916 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1917 false, // Reference discovery is not atomic 1918 &_is_alive_closure_cm, // is alive closure 1919 true); // allow changes to number of processing threads 1920 1921 // STW ref processor 1922 _ref_processor_stw = 1923 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1924 mt_processing, // mt processing 1925 ParallelGCThreads, // degree of mt processing 1926 (ParallelGCThreads > 1), // mt discovery 1927 ParallelGCThreads, // degree of mt discovery 1928 true, // Reference discovery is atomic 1929 &_is_alive_closure_stw, // is alive closure 1930 true); // allow changes to number of processing threads 1931 } 1932 1933 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1934 return &_soft_ref_policy; 1935 } 1936 1937 size_t G1CollectedHeap::capacity() const { 1938 return _hrm->length() * HeapRegion::GrainBytes; 1939 } 1940 1941 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1942 return _hrm->total_free_bytes(); 1943 } 1944 1945 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1946 _hot_card_cache->drain(cl, worker_i); 1947 } 1948 1949 // Computes the sum of the storage used by the various regions. 1950 size_t G1CollectedHeap::used() const { 1951 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1952 if (_archive_allocator != NULL) { 1953 result += _archive_allocator->used(); 1954 } 1955 return result; 1956 } 1957 1958 size_t G1CollectedHeap::used_unlocked() const { 1959 return _summary_bytes_used; 1960 } 1961 1962 class SumUsedClosure: public HeapRegionClosure { 1963 size_t _used; 1964 public: 1965 SumUsedClosure() : _used(0) {} 1966 bool do_heap_region(HeapRegion* r) { 1967 _used += r->used(); 1968 return false; 1969 } 1970 size_t result() { return _used; } 1971 }; 1972 1973 size_t G1CollectedHeap::recalculate_used() const { 1974 SumUsedClosure blk; 1975 heap_region_iterate(&blk); 1976 return blk.result(); 1977 } 1978 1979 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1980 switch (cause) { 1981 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1982 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1983 case GCCause::_wb_conc_mark: return true; 1984 default : return false; 1985 } 1986 } 1987 1988 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1989 switch (cause) { 1990 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1991 case GCCause::_g1_humongous_allocation: return true; 1992 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1993 default: return is_user_requested_concurrent_full_gc(cause); 1994 } 1995 } 1996 1997 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 1998 if(policy()->force_upgrade_to_full()) { 1999 return true; 2000 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2001 return false; 2002 } else if (has_regions_left_for_allocation()) { 2003 return false; 2004 } else { 2005 return true; 2006 } 2007 } 2008 2009 #ifndef PRODUCT 2010 void G1CollectedHeap::allocate_dummy_regions() { 2011 // Let's fill up most of the region 2012 size_t word_size = HeapRegion::GrainWords - 1024; 2013 // And as a result the region we'll allocate will be humongous. 2014 guarantee(is_humongous(word_size), "sanity"); 2015 2016 // _filler_array_max_size is set to humongous object threshold 2017 // but temporarily change it to use CollectedHeap::fill_with_object(). 2018 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2019 2020 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2021 // Let's use the existing mechanism for the allocation 2022 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2023 if (dummy_obj != NULL) { 2024 MemRegion mr(dummy_obj, word_size); 2025 CollectedHeap::fill_with_object(mr); 2026 } else { 2027 // If we can't allocate once, we probably cannot allocate 2028 // again. Let's get out of the loop. 2029 break; 2030 } 2031 } 2032 } 2033 #endif // !PRODUCT 2034 2035 void G1CollectedHeap::increment_old_marking_cycles_started() { 2036 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2037 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2038 "Wrong marking cycle count (started: %d, completed: %d)", 2039 _old_marking_cycles_started, _old_marking_cycles_completed); 2040 2041 _old_marking_cycles_started++; 2042 } 2043 2044 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2045 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2046 2047 // We assume that if concurrent == true, then the caller is a 2048 // concurrent thread that was joined the Suspendible Thread 2049 // Set. If there's ever a cheap way to check this, we should add an 2050 // assert here. 2051 2052 // Given that this method is called at the end of a Full GC or of a 2053 // concurrent cycle, and those can be nested (i.e., a Full GC can 2054 // interrupt a concurrent cycle), the number of full collections 2055 // completed should be either one (in the case where there was no 2056 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2057 // behind the number of full collections started. 2058 2059 // This is the case for the inner caller, i.e. a Full GC. 2060 assert(concurrent || 2061 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2062 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2063 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2064 "is inconsistent with _old_marking_cycles_completed = %u", 2065 _old_marking_cycles_started, _old_marking_cycles_completed); 2066 2067 // This is the case for the outer caller, i.e. the concurrent cycle. 2068 assert(!concurrent || 2069 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2070 "for outer caller (concurrent cycle): " 2071 "_old_marking_cycles_started = %u " 2072 "is inconsistent with _old_marking_cycles_completed = %u", 2073 _old_marking_cycles_started, _old_marking_cycles_completed); 2074 2075 _old_marking_cycles_completed += 1; 2076 2077 // We need to clear the "in_progress" flag in the CM thread before 2078 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2079 // is set) so that if a waiter requests another System.gc() it doesn't 2080 // incorrectly see that a marking cycle is still in progress. 2081 if (concurrent) { 2082 _cm_thread->set_idle(); 2083 } 2084 2085 // This notify_all() will ensure that a thread that called 2086 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2087 // and it's waiting for a full GC to finish will be woken up. It is 2088 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2089 FullGCCount_lock->notify_all(); 2090 } 2091 2092 void G1CollectedHeap::collect(GCCause::Cause cause) { 2093 try_collect(cause, true); 2094 } 2095 2096 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2097 assert_heap_not_locked(); 2098 2099 bool gc_succeeded; 2100 bool should_retry_gc; 2101 2102 do { 2103 should_retry_gc = false; 2104 2105 uint gc_count_before; 2106 uint old_marking_count_before; 2107 uint full_gc_count_before; 2108 2109 { 2110 MutexLocker ml(Heap_lock); 2111 2112 // Read the GC count while holding the Heap_lock 2113 gc_count_before = total_collections(); 2114 full_gc_count_before = total_full_collections(); 2115 old_marking_count_before = _old_marking_cycles_started; 2116 } 2117 2118 if (should_do_concurrent_full_gc(cause)) { 2119 // Schedule an initial-mark evacuation pause that will start a 2120 // concurrent cycle. We're setting word_size to 0 which means that 2121 // we are not requesting a post-GC allocation. 2122 VM_G1CollectForAllocation op(0, /* word_size */ 2123 gc_count_before, 2124 cause, 2125 true, /* should_initiate_conc_mark */ 2126 policy()->max_pause_time_ms()); 2127 VMThread::execute(&op); 2128 gc_succeeded = op.gc_succeeded(); 2129 if (!gc_succeeded && retry_on_gc_failure) { 2130 if (old_marking_count_before == _old_marking_cycles_started) { 2131 should_retry_gc = op.should_retry_gc(); 2132 } else { 2133 // A Full GC happened while we were trying to schedule the 2134 // concurrent cycle. No point in starting a new cycle given 2135 // that the whole heap was collected anyway. 2136 } 2137 2138 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2139 GCLocker::stall_until_clear(); 2140 } 2141 } 2142 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2143 // Return false to be consistent with VMOp failure due to 2144 // another collection slipping in after our gc_count but before 2145 // our request is processed. _gc_locker collections upgraded by 2146 // GCLockerInvokesConcurrent are handled above and never discarded. 2147 return false; 2148 } else { 2149 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2150 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2151 2152 // Schedule a standard evacuation pause. We're setting word_size 2153 // to 0 which means that we are not requesting a post-GC allocation. 2154 VM_G1CollectForAllocation op(0, /* word_size */ 2155 gc_count_before, 2156 cause, 2157 false, /* should_initiate_conc_mark */ 2158 policy()->max_pause_time_ms()); 2159 VMThread::execute(&op); 2160 gc_succeeded = op.gc_succeeded(); 2161 } else { 2162 // Schedule a Full GC. 2163 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2164 VMThread::execute(&op); 2165 gc_succeeded = op.gc_succeeded(); 2166 } 2167 } 2168 } while (should_retry_gc); 2169 return gc_succeeded; 2170 } 2171 2172 bool G1CollectedHeap::is_in(const void* p) const { 2173 if (_hrm->reserved().contains(p)) { 2174 // Given that we know that p is in the reserved space, 2175 // heap_region_containing() should successfully 2176 // return the containing region. 2177 HeapRegion* hr = heap_region_containing(p); 2178 return hr->is_in(p); 2179 } else { 2180 return false; 2181 } 2182 } 2183 2184 #ifdef ASSERT 2185 bool G1CollectedHeap::is_in_exact(const void* p) const { 2186 bool contains = reserved_region().contains(p); 2187 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2188 if (contains && available) { 2189 return true; 2190 } else { 2191 return false; 2192 } 2193 } 2194 #endif 2195 2196 // Iteration functions. 2197 2198 // Iterates an ObjectClosure over all objects within a HeapRegion. 2199 2200 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2201 ObjectClosure* _cl; 2202 public: 2203 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2204 bool do_heap_region(HeapRegion* r) { 2205 if (!r->is_continues_humongous()) { 2206 r->object_iterate(_cl); 2207 } 2208 return false; 2209 } 2210 }; 2211 2212 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2213 IterateObjectClosureRegionClosure blk(cl); 2214 heap_region_iterate(&blk); 2215 } 2216 2217 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2218 _hrm->iterate(cl); 2219 } 2220 2221 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2222 HeapRegionClaimer *hrclaimer, 2223 uint worker_id) const { 2224 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2225 } 2226 2227 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2228 HeapRegionClaimer *hrclaimer) const { 2229 _hrm->par_iterate(cl, hrclaimer, 0); 2230 } 2231 2232 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2233 _collection_set.iterate(cl); 2234 } 2235 2236 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2237 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2238 } 2239 2240 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2241 HeapRegion* hr = heap_region_containing(addr); 2242 return hr->block_start(addr); 2243 } 2244 2245 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2246 HeapRegion* hr = heap_region_containing(addr); 2247 return hr->block_is_obj(addr); 2248 } 2249 2250 bool G1CollectedHeap::supports_tlab_allocation() const { 2251 return true; 2252 } 2253 2254 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2255 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2256 } 2257 2258 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2259 return _eden.length() * HeapRegion::GrainBytes; 2260 } 2261 2262 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2263 // must be equal to the humongous object limit. 2264 size_t G1CollectedHeap::max_tlab_size() const { 2265 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2266 } 2267 2268 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2269 return _allocator->unsafe_max_tlab_alloc(); 2270 } 2271 2272 size_t G1CollectedHeap::max_capacity() const { 2273 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2274 } 2275 2276 size_t G1CollectedHeap::max_reserved_capacity() const { 2277 return _hrm->max_length() * HeapRegion::GrainBytes; 2278 } 2279 2280 jlong G1CollectedHeap::millis_since_last_gc() { 2281 // See the notes in GenCollectedHeap::millis_since_last_gc() 2282 // for more information about the implementation. 2283 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2284 _policy->collection_pause_end_millis(); 2285 if (ret_val < 0) { 2286 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2287 ". returning zero instead.", ret_val); 2288 return 0; 2289 } 2290 return ret_val; 2291 } 2292 2293 void G1CollectedHeap::deduplicate_string(oop str) { 2294 assert(java_lang_String::is_instance(str), "invariant"); 2295 2296 if (G1StringDedup::is_enabled()) { 2297 G1StringDedup::deduplicate(str); 2298 } 2299 } 2300 2301 void G1CollectedHeap::prepare_for_verify() { 2302 _verifier->prepare_for_verify(); 2303 } 2304 2305 void G1CollectedHeap::verify(VerifyOption vo) { 2306 _verifier->verify(vo); 2307 } 2308 2309 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2310 return true; 2311 } 2312 2313 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2314 return _cm_thread->request_concurrent_phase(phase); 2315 } 2316 2317 bool G1CollectedHeap::is_heterogeneous_heap() const { 2318 return G1Arguments::is_heterogeneous_heap(); 2319 } 2320 2321 class PrintRegionClosure: public HeapRegionClosure { 2322 outputStream* _st; 2323 public: 2324 PrintRegionClosure(outputStream* st) : _st(st) {} 2325 bool do_heap_region(HeapRegion* r) { 2326 r->print_on(_st); 2327 return false; 2328 } 2329 }; 2330 2331 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2332 const HeapRegion* hr, 2333 const VerifyOption vo) const { 2334 switch (vo) { 2335 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2336 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2337 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2338 default: ShouldNotReachHere(); 2339 } 2340 return false; // keep some compilers happy 2341 } 2342 2343 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2344 const VerifyOption vo) const { 2345 switch (vo) { 2346 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2347 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2348 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2349 default: ShouldNotReachHere(); 2350 } 2351 return false; // keep some compilers happy 2352 } 2353 2354 void G1CollectedHeap::print_heap_regions() const { 2355 LogTarget(Trace, gc, heap, region) lt; 2356 if (lt.is_enabled()) { 2357 LogStream ls(lt); 2358 print_regions_on(&ls); 2359 } 2360 } 2361 2362 void G1CollectedHeap::print_on(outputStream* st) const { 2363 st->print(" %-20s", "garbage-first heap"); 2364 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2365 capacity()/K, used_unlocked()/K); 2366 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2367 p2i(_hrm->reserved().start()), 2368 p2i(_hrm->reserved().end())); 2369 st->cr(); 2370 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2371 uint young_regions = young_regions_count(); 2372 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2373 (size_t) young_regions * HeapRegion::GrainBytes / K); 2374 uint survivor_regions = survivor_regions_count(); 2375 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2376 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2377 st->cr(); 2378 MetaspaceUtils::print_on(st); 2379 } 2380 2381 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2382 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2383 "HS=humongous(starts), HC=humongous(continues), " 2384 "CS=collection set, F=free, A=archive, " 2385 "TAMS=top-at-mark-start (previous, next)"); 2386 PrintRegionClosure blk(st); 2387 heap_region_iterate(&blk); 2388 } 2389 2390 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2391 print_on(st); 2392 2393 // Print the per-region information. 2394 print_regions_on(st); 2395 } 2396 2397 void G1CollectedHeap::print_on_error(outputStream* st) const { 2398 this->CollectedHeap::print_on_error(st); 2399 2400 if (_cm != NULL) { 2401 st->cr(); 2402 _cm->print_on_error(st); 2403 } 2404 } 2405 2406 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2407 workers()->print_worker_threads_on(st); 2408 _cm_thread->print_on(st); 2409 st->cr(); 2410 _cm->print_worker_threads_on(st); 2411 _cr->print_threads_on(st); 2412 _young_gen_sampling_thread->print_on(st); 2413 if (G1StringDedup::is_enabled()) { 2414 G1StringDedup::print_worker_threads_on(st); 2415 } 2416 } 2417 2418 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2419 workers()->threads_do(tc); 2420 tc->do_thread(_cm_thread); 2421 _cm->threads_do(tc); 2422 _cr->threads_do(tc); 2423 tc->do_thread(_young_gen_sampling_thread); 2424 if (G1StringDedup::is_enabled()) { 2425 G1StringDedup::threads_do(tc); 2426 } 2427 } 2428 2429 void G1CollectedHeap::print_tracing_info() const { 2430 rem_set()->print_summary_info(); 2431 concurrent_mark()->print_summary_info(); 2432 } 2433 2434 #ifndef PRODUCT 2435 // Helpful for debugging RSet issues. 2436 2437 class PrintRSetsClosure : public HeapRegionClosure { 2438 private: 2439 const char* _msg; 2440 size_t _occupied_sum; 2441 2442 public: 2443 bool do_heap_region(HeapRegion* r) { 2444 HeapRegionRemSet* hrrs = r->rem_set(); 2445 size_t occupied = hrrs->occupied(); 2446 _occupied_sum += occupied; 2447 2448 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2449 if (occupied == 0) { 2450 tty->print_cr(" RSet is empty"); 2451 } else { 2452 hrrs->print(); 2453 } 2454 tty->print_cr("----------"); 2455 return false; 2456 } 2457 2458 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2459 tty->cr(); 2460 tty->print_cr("========================================"); 2461 tty->print_cr("%s", msg); 2462 tty->cr(); 2463 } 2464 2465 ~PrintRSetsClosure() { 2466 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2467 tty->print_cr("========================================"); 2468 tty->cr(); 2469 } 2470 }; 2471 2472 void G1CollectedHeap::print_cset_rsets() { 2473 PrintRSetsClosure cl("Printing CSet RSets"); 2474 collection_set_iterate_all(&cl); 2475 } 2476 2477 void G1CollectedHeap::print_all_rsets() { 2478 PrintRSetsClosure cl("Printing All RSets");; 2479 heap_region_iterate(&cl); 2480 } 2481 #endif // PRODUCT 2482 2483 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2484 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2485 } 2486 2487 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2488 2489 size_t eden_used_bytes = _eden.used_bytes(); 2490 size_t survivor_used_bytes = _survivor.used_bytes(); 2491 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2492 2493 size_t eden_capacity_bytes = 2494 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2495 2496 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2497 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2498 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2499 } 2500 2501 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2502 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2503 stats->unused(), stats->used(), stats->region_end_waste(), 2504 stats->regions_filled(), stats->direct_allocated(), 2505 stats->failure_used(), stats->failure_waste()); 2506 } 2507 2508 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2509 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2510 gc_tracer->report_gc_heap_summary(when, heap_summary); 2511 2512 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2513 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2514 } 2515 2516 G1CollectedHeap* G1CollectedHeap::heap() { 2517 CollectedHeap* heap = Universe::heap(); 2518 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2519 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2520 return (G1CollectedHeap*)heap; 2521 } 2522 2523 void G1CollectedHeap::gc_prologue(bool full) { 2524 // always_do_update_barrier = false; 2525 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2526 2527 // This summary needs to be printed before incrementing total collections. 2528 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2529 2530 // Update common counters. 2531 increment_total_collections(full /* full gc */); 2532 if (full || collector_state()->in_initial_mark_gc()) { 2533 increment_old_marking_cycles_started(); 2534 } 2535 2536 // Fill TLAB's and such 2537 double start = os::elapsedTime(); 2538 ensure_parsability(true); 2539 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2540 } 2541 2542 void G1CollectedHeap::gc_epilogue(bool full) { 2543 // Update common counters. 2544 if (full) { 2545 // Update the number of full collections that have been completed. 2546 increment_old_marking_cycles_completed(false /* concurrent */); 2547 } 2548 2549 // We are at the end of the GC. Total collections has already been increased. 2550 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2551 2552 // FIXME: what is this about? 2553 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2554 // is set. 2555 #if COMPILER2_OR_JVMCI 2556 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2557 #endif 2558 // always_do_update_barrier = true; 2559 2560 double start = os::elapsedTime(); 2561 resize_all_tlabs(); 2562 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2563 2564 MemoryService::track_memory_usage(); 2565 // We have just completed a GC. Update the soft reference 2566 // policy with the new heap occupancy 2567 Universe::update_heap_info_at_gc(); 2568 } 2569 2570 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2571 uint gc_count_before, 2572 bool* succeeded, 2573 GCCause::Cause gc_cause) { 2574 assert_heap_not_locked_and_not_at_safepoint(); 2575 VM_G1CollectForAllocation op(word_size, 2576 gc_count_before, 2577 gc_cause, 2578 false, /* should_initiate_conc_mark */ 2579 policy()->max_pause_time_ms()); 2580 VMThread::execute(&op); 2581 2582 HeapWord* result = op.result(); 2583 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2584 assert(result == NULL || ret_succeeded, 2585 "the result should be NULL if the VM did not succeed"); 2586 *succeeded = ret_succeeded; 2587 2588 assert_heap_not_locked(); 2589 return result; 2590 } 2591 2592 void G1CollectedHeap::do_concurrent_mark() { 2593 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2594 if (!_cm_thread->in_progress()) { 2595 _cm_thread->set_started(); 2596 CGC_lock->notify(); 2597 } 2598 } 2599 2600 size_t G1CollectedHeap::pending_card_num() { 2601 struct CountCardsClosure : public ThreadClosure { 2602 size_t _cards; 2603 CountCardsClosure() : _cards(0) {} 2604 virtual void do_thread(Thread* t) { 2605 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2606 } 2607 } count_from_threads; 2608 Threads::threads_do(&count_from_threads); 2609 2610 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2611 dcqs.verify_num_cards(); 2612 2613 return dcqs.num_cards() + count_from_threads._cards; 2614 } 2615 2616 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2617 // We don't nominate objects with many remembered set entries, on 2618 // the assumption that such objects are likely still live. 2619 HeapRegionRemSet* rem_set = r->rem_set(); 2620 2621 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2622 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2623 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2624 } 2625 2626 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure { 2627 private: 2628 size_t _total_humongous; 2629 size_t _candidate_humongous; 2630 2631 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2632 assert(region->is_starts_humongous(), "Must start a humongous object"); 2633 2634 oop obj = oop(region->bottom()); 2635 2636 // Dead objects cannot be eager reclaim candidates. Due to class 2637 // unloading it is unsafe to query their classes so we return early. 2638 if (g1h->is_obj_dead(obj, region)) { 2639 return false; 2640 } 2641 2642 // If we do not have a complete remembered set for the region, then we can 2643 // not be sure that we have all references to it. 2644 if (!region->rem_set()->is_complete()) { 2645 return false; 2646 } 2647 // Candidate selection must satisfy the following constraints 2648 // while concurrent marking is in progress: 2649 // 2650 // * In order to maintain SATB invariants, an object must not be 2651 // reclaimed if it was allocated before the start of marking and 2652 // has not had its references scanned. Such an object must have 2653 // its references (including type metadata) scanned to ensure no 2654 // live objects are missed by the marking process. Objects 2655 // allocated after the start of concurrent marking don't need to 2656 // be scanned. 2657 // 2658 // * An object must not be reclaimed if it is on the concurrent 2659 // mark stack. Objects allocated after the start of concurrent 2660 // marking are never pushed on the mark stack. 2661 // 2662 // Nominating only objects allocated after the start of concurrent 2663 // marking is sufficient to meet both constraints. This may miss 2664 // some objects that satisfy the constraints, but the marking data 2665 // structures don't support efficiently performing the needed 2666 // additional tests or scrubbing of the mark stack. 2667 // 2668 // However, we presently only nominate is_typeArray() objects. 2669 // A humongous object containing references induces remembered 2670 // set entries on other regions. In order to reclaim such an 2671 // object, those remembered sets would need to be cleaned up. 2672 // 2673 // We also treat is_typeArray() objects specially, allowing them 2674 // to be reclaimed even if allocated before the start of 2675 // concurrent mark. For this we rely on mark stack insertion to 2676 // exclude is_typeArray() objects, preventing reclaiming an object 2677 // that is in the mark stack. We also rely on the metadata for 2678 // such objects to be built-in and so ensured to be kept live. 2679 // Frequent allocation and drop of large binary blobs is an 2680 // important use case for eager reclaim, and this special handling 2681 // may reduce needed headroom. 2682 2683 return obj->is_typeArray() && 2684 g1h->is_potential_eager_reclaim_candidate(region); 2685 } 2686 2687 public: 2688 RegisterRegionsWithRegionAttrTableClosure() 2689 : _total_humongous(0), 2690 _candidate_humongous(0) { 2691 } 2692 2693 virtual bool do_heap_region(HeapRegion* r) { 2694 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2695 2696 if (!r->is_starts_humongous()) { 2697 g1h->register_region_with_region_attr(r); 2698 return false; 2699 } 2700 2701 bool is_candidate = humongous_region_is_candidate(g1h, r); 2702 uint rindex = r->hrm_index(); 2703 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2704 if (is_candidate) { 2705 g1h->register_humongous_region_with_region_attr(rindex); 2706 _candidate_humongous++; 2707 // We will later handle the remembered sets of these regions. 2708 } else { 2709 g1h->register_region_with_region_attr(r); 2710 } 2711 _total_humongous++; 2712 2713 return false; 2714 } 2715 2716 size_t total_humongous() const { return _total_humongous; } 2717 size_t candidate_humongous() const { return _candidate_humongous; } 2718 }; 2719 2720 void G1CollectedHeap::register_regions_with_region_attr() { 2721 Ticks start = Ticks::now(); 2722 2723 RegisterRegionsWithRegionAttrTableClosure cl; 2724 heap_region_iterate(&cl); 2725 2726 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0, 2727 cl.total_humongous(), 2728 cl.candidate_humongous()); 2729 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2730 } 2731 2732 #ifndef PRODUCT 2733 void G1CollectedHeap::verify_region_attr_remset_update() { 2734 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2735 public: 2736 virtual bool do_heap_region(HeapRegion* r) { 2737 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2738 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2739 assert(r->rem_set()->is_tracked() == needs_remset_update, 2740 "Region %u remset tracking status (%s) different to region attribute (%s)", 2741 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2742 return false; 2743 } 2744 } cl; 2745 heap_region_iterate(&cl); 2746 } 2747 #endif 2748 2749 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2750 public: 2751 bool do_heap_region(HeapRegion* hr) { 2752 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2753 hr->verify_rem_set(); 2754 } 2755 return false; 2756 } 2757 }; 2758 2759 uint G1CollectedHeap::num_task_queues() const { 2760 return _task_queues->size(); 2761 } 2762 2763 #if TASKQUEUE_STATS 2764 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2765 st->print_raw_cr("GC Task Stats"); 2766 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2767 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2768 } 2769 2770 void G1CollectedHeap::print_taskqueue_stats() const { 2771 if (!log_is_enabled(Trace, gc, task, stats)) { 2772 return; 2773 } 2774 Log(gc, task, stats) log; 2775 ResourceMark rm; 2776 LogStream ls(log.trace()); 2777 outputStream* st = &ls; 2778 2779 print_taskqueue_stats_hdr(st); 2780 2781 TaskQueueStats totals; 2782 const uint n = num_task_queues(); 2783 for (uint i = 0; i < n; ++i) { 2784 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2785 totals += task_queue(i)->stats; 2786 } 2787 st->print_raw("tot "); totals.print(st); st->cr(); 2788 2789 DEBUG_ONLY(totals.verify()); 2790 } 2791 2792 void G1CollectedHeap::reset_taskqueue_stats() { 2793 const uint n = num_task_queues(); 2794 for (uint i = 0; i < n; ++i) { 2795 task_queue(i)->stats.reset(); 2796 } 2797 } 2798 #endif // TASKQUEUE_STATS 2799 2800 void G1CollectedHeap::wait_for_root_region_scanning() { 2801 double scan_wait_start = os::elapsedTime(); 2802 // We have to wait until the CM threads finish scanning the 2803 // root regions as it's the only way to ensure that all the 2804 // objects on them have been correctly scanned before we start 2805 // moving them during the GC. 2806 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2807 double wait_time_ms = 0.0; 2808 if (waited) { 2809 double scan_wait_end = os::elapsedTime(); 2810 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2811 } 2812 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2813 } 2814 2815 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2816 private: 2817 G1HRPrinter* _hr_printer; 2818 public: 2819 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2820 2821 virtual bool do_heap_region(HeapRegion* r) { 2822 _hr_printer->cset(r); 2823 return false; 2824 } 2825 }; 2826 2827 void G1CollectedHeap::start_new_collection_set() { 2828 double start = os::elapsedTime(); 2829 2830 collection_set()->start_incremental_building(); 2831 2832 clear_region_attr(); 2833 2834 guarantee(_eden.length() == 0, "eden should have been cleared"); 2835 policy()->transfer_survivors_to_cset(survivor()); 2836 2837 // We redo the verification but now wrt to the new CSet which 2838 // has just got initialized after the previous CSet was freed. 2839 _cm->verify_no_collection_set_oops(); 2840 2841 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2842 } 2843 2844 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2845 2846 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2847 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2848 collection_set()->optional_region_length()); 2849 2850 _cm->verify_no_collection_set_oops(); 2851 2852 if (_hr_printer.is_active()) { 2853 G1PrintCollectionSetClosure cl(&_hr_printer); 2854 _collection_set.iterate(&cl); 2855 _collection_set.iterate_optional(&cl); 2856 } 2857 } 2858 2859 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2860 if (collector_state()->in_initial_mark_gc()) { 2861 return G1HeapVerifier::G1VerifyConcurrentStart; 2862 } else if (collector_state()->in_young_only_phase()) { 2863 return G1HeapVerifier::G1VerifyYoungNormal; 2864 } else { 2865 return G1HeapVerifier::G1VerifyMixed; 2866 } 2867 } 2868 2869 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2870 if (VerifyRememberedSets) { 2871 log_info(gc, verify)("[Verifying RemSets before GC]"); 2872 VerifyRegionRemSetClosure v_cl; 2873 heap_region_iterate(&v_cl); 2874 } 2875 _verifier->verify_before_gc(type); 2876 _verifier->check_bitmaps("GC Start"); 2877 } 2878 2879 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2880 if (VerifyRememberedSets) { 2881 log_info(gc, verify)("[Verifying RemSets after GC]"); 2882 VerifyRegionRemSetClosure v_cl; 2883 heap_region_iterate(&v_cl); 2884 } 2885 _verifier->verify_after_gc(type); 2886 _verifier->check_bitmaps("GC End"); 2887 } 2888 2889 void G1CollectedHeap::expand_heap_after_young_collection(){ 2890 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2891 if (expand_bytes > 0) { 2892 // No need for an ergo logging here, 2893 // expansion_amount() does this when it returns a value > 0. 2894 double expand_ms; 2895 if (!expand(expand_bytes, _workers, &expand_ms)) { 2896 // We failed to expand the heap. Cannot do anything about it. 2897 } 2898 phase_times()->record_expand_heap_time(expand_ms); 2899 } 2900 } 2901 2902 const char* G1CollectedHeap::young_gc_name() const { 2903 if (collector_state()->in_initial_mark_gc()) { 2904 return "Pause Young (Concurrent Start)"; 2905 } else if (collector_state()->in_young_only_phase()) { 2906 if (collector_state()->in_young_gc_before_mixed()) { 2907 return "Pause Young (Prepare Mixed)"; 2908 } else { 2909 return "Pause Young (Normal)"; 2910 } 2911 } else { 2912 return "Pause Young (Mixed)"; 2913 } 2914 } 2915 2916 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2917 assert_at_safepoint_on_vm_thread(); 2918 guarantee(!is_gc_active(), "collection is not reentrant"); 2919 2920 if (GCLocker::check_active_before_gc()) { 2921 return false; 2922 } 2923 2924 GCIdMark gc_id_mark; 2925 2926 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2927 ResourceMark rm; 2928 2929 policy()->note_gc_start(); 2930 2931 _gc_timer_stw->register_gc_start(); 2932 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2933 2934 wait_for_root_region_scanning(); 2935 2936 print_heap_before_gc(); 2937 print_heap_regions(); 2938 trace_heap_before_gc(_gc_tracer_stw); 2939 2940 _verifier->verify_region_sets_optional(); 2941 _verifier->verify_dirty_young_regions(); 2942 2943 // We should not be doing initial mark unless the conc mark thread is running 2944 if (!_cm_thread->should_terminate()) { 2945 // This call will decide whether this pause is an initial-mark 2946 // pause. If it is, in_initial_mark_gc() will return true 2947 // for the duration of this pause. 2948 policy()->decide_on_conc_mark_initiation(); 2949 } 2950 2951 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2952 assert(!collector_state()->in_initial_mark_gc() || 2953 collector_state()->in_young_only_phase(), "sanity"); 2954 // We also do not allow mixed GCs during marking. 2955 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2956 2957 // Record whether this pause is an initial mark. When the current 2958 // thread has completed its logging output and it's safe to signal 2959 // the CM thread, the flag's value in the policy has been reset. 2960 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2961 if (should_start_conc_mark) { 2962 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2963 } 2964 2965 // Inner scope for scope based logging, timers, and stats collection 2966 { 2967 G1EvacuationInfo evacuation_info; 2968 2969 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2970 2971 GCTraceCPUTime tcpu; 2972 2973 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 2974 2975 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2976 workers()->active_workers(), 2977 Threads::number_of_non_daemon_threads()); 2978 active_workers = workers()->update_active_workers(active_workers); 2979 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2980 2981 G1MonitoringScope ms(g1mm(), 2982 false /* full_gc */, 2983 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2984 2985 G1HeapTransition heap_transition(this); 2986 size_t heap_used_bytes_before_gc = used(); 2987 2988 { 2989 IsGCActiveMark x; 2990 2991 gc_prologue(false); 2992 2993 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 2994 verify_before_young_collection(verify_type); 2995 2996 { 2997 // The elapsed time induced by the start time below deliberately elides 2998 // the possible verification above. 2999 double sample_start_time_sec = os::elapsedTime(); 3000 3001 // Please see comment in g1CollectedHeap.hpp and 3002 // G1CollectedHeap::ref_processing_init() to see how 3003 // reference processing currently works in G1. 3004 _ref_processor_stw->enable_discovery(); 3005 3006 // We want to temporarily turn off discovery by the 3007 // CM ref processor, if necessary, and turn it back on 3008 // on again later if we do. Using a scoped 3009 // NoRefDiscovery object will do this. 3010 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3011 3012 policy()->record_collection_pause_start(sample_start_time_sec); 3013 3014 // Forget the current allocation region (we might even choose it to be part 3015 // of the collection set!). 3016 _allocator->release_mutator_alloc_region(); 3017 3018 calculate_collection_set(evacuation_info, target_pause_time_ms); 3019 3020 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3021 G1ParScanThreadStateSet per_thread_states(this, 3022 &rdcqs, 3023 workers()->active_workers(), 3024 collection_set()->young_region_length(), 3025 collection_set()->optional_region_length()); 3026 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3027 3028 // Actually do the work... 3029 evacuate_initial_collection_set(&per_thread_states); 3030 3031 if (_collection_set.optional_region_length() != 0) { 3032 evacuate_optional_collection_set(&per_thread_states); 3033 } 3034 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3035 3036 start_new_collection_set(); 3037 3038 _survivor_evac_stats.adjust_desired_plab_sz(); 3039 _old_evac_stats.adjust_desired_plab_sz(); 3040 3041 if (should_start_conc_mark) { 3042 // We have to do this before we notify the CM threads that 3043 // they can start working to make sure that all the 3044 // appropriate initialization is done on the CM object. 3045 concurrent_mark()->post_initial_mark(); 3046 // Note that we don't actually trigger the CM thread at 3047 // this point. We do that later when we're sure that 3048 // the current thread has completed its logging output. 3049 } 3050 3051 allocate_dummy_regions(); 3052 3053 _allocator->init_mutator_alloc_region(); 3054 3055 expand_heap_after_young_collection(); 3056 3057 double sample_end_time_sec = os::elapsedTime(); 3058 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3059 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc); 3060 } 3061 3062 verify_after_young_collection(verify_type); 3063 3064 #ifdef TRACESPINNING 3065 ParallelTaskTerminator::print_termination_counts(); 3066 #endif 3067 3068 gc_epilogue(false); 3069 } 3070 3071 // Print the remainder of the GC log output. 3072 if (evacuation_failed()) { 3073 log_info(gc)("To-space exhausted"); 3074 } 3075 3076 policy()->print_phases(); 3077 heap_transition.print(); 3078 3079 _hrm->verify_optional(); 3080 _verifier->verify_region_sets_optional(); 3081 3082 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3083 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3084 3085 print_heap_after_gc(); 3086 print_heap_regions(); 3087 trace_heap_after_gc(_gc_tracer_stw); 3088 3089 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3090 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3091 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3092 // before any GC notifications are raised. 3093 g1mm()->update_sizes(); 3094 3095 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3096 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3097 _gc_timer_stw->register_gc_end(); 3098 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3099 } 3100 // It should now be safe to tell the concurrent mark thread to start 3101 // without its logging output interfering with the logging output 3102 // that came from the pause. 3103 3104 if (should_start_conc_mark) { 3105 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3106 // thread(s) could be running concurrently with us. Make sure that anything 3107 // after this point does not assume that we are the only GC thread running. 3108 // Note: of course, the actual marking work will not start until the safepoint 3109 // itself is released in SuspendibleThreadSet::desynchronize(). 3110 do_concurrent_mark(); 3111 } 3112 3113 return true; 3114 } 3115 3116 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3117 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3118 workers()->run_task(&rsfp_task); 3119 } 3120 3121 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3122 double remove_self_forwards_start = os::elapsedTime(); 3123 3124 remove_self_forwarding_pointers(rdcqs); 3125 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3126 _preserved_marks_set.restore(&task_executor); 3127 3128 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3129 } 3130 3131 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3132 if (!_evacuation_failed) { 3133 _evacuation_failed = true; 3134 } 3135 3136 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3137 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3138 } 3139 3140 bool G1ParEvacuateFollowersClosure::offer_termination() { 3141 EventGCPhaseParallel event; 3142 G1ParScanThreadState* const pss = par_scan_state(); 3143 start_term_time(); 3144 const bool res = terminator()->offer_termination(); 3145 end_term_time(); 3146 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3147 return res; 3148 } 3149 3150 void G1ParEvacuateFollowersClosure::do_void() { 3151 EventGCPhaseParallel event; 3152 G1ParScanThreadState* const pss = par_scan_state(); 3153 pss->trim_queue(); 3154 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3155 do { 3156 EventGCPhaseParallel event; 3157 pss->steal_and_trim_queue(queues()); 3158 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3159 } while (!offer_termination()); 3160 } 3161 3162 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3163 bool class_unloading_occurred) { 3164 uint num_workers = workers()->active_workers(); 3165 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3166 workers()->run_task(&unlink_task); 3167 } 3168 3169 // Clean string dedup data structures. 3170 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3171 // record the durations of the phases. Hence the almost-copy. 3172 class G1StringDedupCleaningTask : public AbstractGangTask { 3173 BoolObjectClosure* _is_alive; 3174 OopClosure* _keep_alive; 3175 G1GCPhaseTimes* _phase_times; 3176 3177 public: 3178 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3179 OopClosure* keep_alive, 3180 G1GCPhaseTimes* phase_times) : 3181 AbstractGangTask("Partial Cleaning Task"), 3182 _is_alive(is_alive), 3183 _keep_alive(keep_alive), 3184 _phase_times(phase_times) 3185 { 3186 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3187 StringDedup::gc_prologue(true); 3188 } 3189 3190 ~G1StringDedupCleaningTask() { 3191 StringDedup::gc_epilogue(); 3192 } 3193 3194 void work(uint worker_id) { 3195 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3196 { 3197 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3198 StringDedupQueue::unlink_or_oops_do(&cl); 3199 } 3200 { 3201 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3202 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3203 } 3204 } 3205 }; 3206 3207 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3208 OopClosure* keep_alive, 3209 G1GCPhaseTimes* phase_times) { 3210 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3211 workers()->run_task(&cl); 3212 } 3213 3214 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3215 private: 3216 G1RedirtyCardsQueueSet* _qset; 3217 G1CollectedHeap* _g1h; 3218 BufferNode* volatile _nodes; 3219 3220 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3221 size_t buffer_size = _qset->buffer_size(); 3222 BufferNode* next = Atomic::load(&_nodes); 3223 while (next != NULL) { 3224 BufferNode* node = next; 3225 next = Atomic::cmpxchg(node->next(), &_nodes, node); 3226 if (next == node) { 3227 cl->apply_to_buffer(node, buffer_size, worker_id); 3228 next = node->next(); 3229 } 3230 } 3231 } 3232 3233 public: 3234 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3235 AbstractGangTask("Redirty Cards"), 3236 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3237 3238 virtual void work(uint worker_id) { 3239 G1GCPhaseTimes* p = _g1h->phase_times(); 3240 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3241 3242 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3243 par_apply(&cl, worker_id); 3244 3245 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3246 } 3247 }; 3248 3249 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3250 double redirty_logged_cards_start = os::elapsedTime(); 3251 3252 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3253 workers()->run_task(&redirty_task); 3254 3255 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3256 dcq.merge_bufferlists(rdcqs); 3257 3258 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3259 } 3260 3261 // Weak Reference Processing support 3262 3263 bool G1STWIsAliveClosure::do_object_b(oop p) { 3264 // An object is reachable if it is outside the collection set, 3265 // or is inside and copied. 3266 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3267 } 3268 3269 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3270 assert(obj != NULL, "must not be NULL"); 3271 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3272 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3273 // may falsely indicate that this is not the case here: however the collection set only 3274 // contains old regions when concurrent mark is not running. 3275 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3276 } 3277 3278 // Non Copying Keep Alive closure 3279 class G1KeepAliveClosure: public OopClosure { 3280 G1CollectedHeap*_g1h; 3281 public: 3282 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3283 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3284 void do_oop(oop* p) { 3285 oop obj = *p; 3286 assert(obj != NULL, "the caller should have filtered out NULL values"); 3287 3288 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3289 if (!region_attr.is_in_cset_or_humongous()) { 3290 return; 3291 } 3292 if (region_attr.is_in_cset()) { 3293 assert( obj->is_forwarded(), "invariant" ); 3294 *p = obj->forwardee(); 3295 } else { 3296 assert(!obj->is_forwarded(), "invariant" ); 3297 assert(region_attr.is_humongous(), 3298 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3299 _g1h->set_humongous_is_live(obj); 3300 } 3301 } 3302 }; 3303 3304 // Copying Keep Alive closure - can be called from both 3305 // serial and parallel code as long as different worker 3306 // threads utilize different G1ParScanThreadState instances 3307 // and different queues. 3308 3309 class G1CopyingKeepAliveClosure: public OopClosure { 3310 G1CollectedHeap* _g1h; 3311 G1ParScanThreadState* _par_scan_state; 3312 3313 public: 3314 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3315 G1ParScanThreadState* pss): 3316 _g1h(g1h), 3317 _par_scan_state(pss) 3318 {} 3319 3320 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3321 virtual void do_oop( oop* p) { do_oop_work(p); } 3322 3323 template <class T> void do_oop_work(T* p) { 3324 oop obj = RawAccess<>::oop_load(p); 3325 3326 if (_g1h->is_in_cset_or_humongous(obj)) { 3327 // If the referent object has been forwarded (either copied 3328 // to a new location or to itself in the event of an 3329 // evacuation failure) then we need to update the reference 3330 // field and, if both reference and referent are in the G1 3331 // heap, update the RSet for the referent. 3332 // 3333 // If the referent has not been forwarded then we have to keep 3334 // it alive by policy. Therefore we have copy the referent. 3335 // 3336 // When the queue is drained (after each phase of reference processing) 3337 // the object and it's followers will be copied, the reference field set 3338 // to point to the new location, and the RSet updated. 3339 _par_scan_state->push_on_queue(p); 3340 } 3341 } 3342 }; 3343 3344 // Serial drain queue closure. Called as the 'complete_gc' 3345 // closure for each discovered list in some of the 3346 // reference processing phases. 3347 3348 class G1STWDrainQueueClosure: public VoidClosure { 3349 protected: 3350 G1CollectedHeap* _g1h; 3351 G1ParScanThreadState* _par_scan_state; 3352 3353 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3354 3355 public: 3356 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3357 _g1h(g1h), 3358 _par_scan_state(pss) 3359 { } 3360 3361 void do_void() { 3362 G1ParScanThreadState* const pss = par_scan_state(); 3363 pss->trim_queue(); 3364 } 3365 }; 3366 3367 // Parallel Reference Processing closures 3368 3369 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3370 // processing during G1 evacuation pauses. 3371 3372 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3373 private: 3374 G1CollectedHeap* _g1h; 3375 G1ParScanThreadStateSet* _pss; 3376 RefToScanQueueSet* _queues; 3377 WorkGang* _workers; 3378 3379 public: 3380 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3381 G1ParScanThreadStateSet* per_thread_states, 3382 WorkGang* workers, 3383 RefToScanQueueSet *task_queues) : 3384 _g1h(g1h), 3385 _pss(per_thread_states), 3386 _queues(task_queues), 3387 _workers(workers) 3388 { 3389 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3390 } 3391 3392 // Executes the given task using concurrent marking worker threads. 3393 virtual void execute(ProcessTask& task, uint ergo_workers); 3394 }; 3395 3396 // Gang task for possibly parallel reference processing 3397 3398 class G1STWRefProcTaskProxy: public AbstractGangTask { 3399 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3400 ProcessTask& _proc_task; 3401 G1CollectedHeap* _g1h; 3402 G1ParScanThreadStateSet* _pss; 3403 RefToScanQueueSet* _task_queues; 3404 ParallelTaskTerminator* _terminator; 3405 3406 public: 3407 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3408 G1CollectedHeap* g1h, 3409 G1ParScanThreadStateSet* per_thread_states, 3410 RefToScanQueueSet *task_queues, 3411 ParallelTaskTerminator* terminator) : 3412 AbstractGangTask("Process reference objects in parallel"), 3413 _proc_task(proc_task), 3414 _g1h(g1h), 3415 _pss(per_thread_states), 3416 _task_queues(task_queues), 3417 _terminator(terminator) 3418 {} 3419 3420 virtual void work(uint worker_id) { 3421 // The reference processing task executed by a single worker. 3422 ResourceMark rm; 3423 HandleMark hm; 3424 3425 G1STWIsAliveClosure is_alive(_g1h); 3426 3427 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3428 pss->set_ref_discoverer(NULL); 3429 3430 // Keep alive closure. 3431 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3432 3433 // Complete GC closure 3434 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3435 3436 // Call the reference processing task's work routine. 3437 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3438 3439 // Note we cannot assert that the refs array is empty here as not all 3440 // of the processing tasks (specifically phase2 - pp2_work) execute 3441 // the complete_gc closure (which ordinarily would drain the queue) so 3442 // the queue may not be empty. 3443 } 3444 }; 3445 3446 // Driver routine for parallel reference processing. 3447 // Creates an instance of the ref processing gang 3448 // task and has the worker threads execute it. 3449 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3450 assert(_workers != NULL, "Need parallel worker threads."); 3451 3452 assert(_workers->active_workers() >= ergo_workers, 3453 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3454 ergo_workers, _workers->active_workers()); 3455 TaskTerminator terminator(ergo_workers, _queues); 3456 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3457 3458 _workers->run_task(&proc_task_proxy, ergo_workers); 3459 } 3460 3461 // End of weak reference support closures 3462 3463 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3464 double ref_proc_start = os::elapsedTime(); 3465 3466 ReferenceProcessor* rp = _ref_processor_stw; 3467 assert(rp->discovery_enabled(), "should have been enabled"); 3468 3469 // Closure to test whether a referent is alive. 3470 G1STWIsAliveClosure is_alive(this); 3471 3472 // Even when parallel reference processing is enabled, the processing 3473 // of JNI refs is serial and performed serially by the current thread 3474 // rather than by a worker. The following PSS will be used for processing 3475 // JNI refs. 3476 3477 // Use only a single queue for this PSS. 3478 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3479 pss->set_ref_discoverer(NULL); 3480 assert(pss->queue_is_empty(), "pre-condition"); 3481 3482 // Keep alive closure. 3483 G1CopyingKeepAliveClosure keep_alive(this, pss); 3484 3485 // Serial Complete GC closure 3486 G1STWDrainQueueClosure drain_queue(this, pss); 3487 3488 // Setup the soft refs policy... 3489 rp->setup_policy(false); 3490 3491 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3492 3493 ReferenceProcessorStats stats; 3494 if (!rp->processing_is_mt()) { 3495 // Serial reference processing... 3496 stats = rp->process_discovered_references(&is_alive, 3497 &keep_alive, 3498 &drain_queue, 3499 NULL, 3500 pt); 3501 } else { 3502 uint no_of_gc_workers = workers()->active_workers(); 3503 3504 // Parallel reference processing 3505 assert(no_of_gc_workers <= rp->max_num_queues(), 3506 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3507 no_of_gc_workers, rp->max_num_queues()); 3508 3509 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3510 stats = rp->process_discovered_references(&is_alive, 3511 &keep_alive, 3512 &drain_queue, 3513 &par_task_executor, 3514 pt); 3515 } 3516 3517 _gc_tracer_stw->report_gc_reference_stats(stats); 3518 3519 // We have completed copying any necessary live referent objects. 3520 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3521 3522 make_pending_list_reachable(); 3523 3524 assert(!rp->discovery_enabled(), "Postcondition"); 3525 rp->verify_no_references_recorded(); 3526 3527 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3528 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3529 } 3530 3531 void G1CollectedHeap::make_pending_list_reachable() { 3532 if (collector_state()->in_initial_mark_gc()) { 3533 oop pll_head = Universe::reference_pending_list(); 3534 if (pll_head != NULL) { 3535 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3536 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3537 } 3538 } 3539 } 3540 3541 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3542 double merge_pss_time_start = os::elapsedTime(); 3543 per_thread_states->flush(); 3544 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3545 } 3546 3547 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3548 _expand_heap_after_alloc_failure = true; 3549 _evacuation_failed = false; 3550 3551 // Disable the hot card cache. 3552 _hot_card_cache->reset_hot_cache_claimed_index(); 3553 _hot_card_cache->set_use_cache(false); 3554 3555 // Initialize the GC alloc regions. 3556 _allocator->init_gc_alloc_regions(evacuation_info); 3557 3558 { 3559 Ticks start = Ticks::now(); 3560 rem_set()->prepare_for_scan_heap_roots(); 3561 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3562 } 3563 3564 register_regions_with_region_attr(); 3565 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3566 3567 _preserved_marks_set.assert_empty(); 3568 3569 #if COMPILER2_OR_JVMCI 3570 DerivedPointerTable::clear(); 3571 #endif 3572 3573 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3574 if (collector_state()->in_initial_mark_gc()) { 3575 concurrent_mark()->pre_initial_mark(); 3576 3577 double start_clear_claimed_marks = os::elapsedTime(); 3578 3579 ClassLoaderDataGraph::clear_claimed_marks(); 3580 3581 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3582 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3583 } 3584 3585 // Should G1EvacuationFailureALot be in effect for this GC? 3586 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3587 } 3588 3589 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3590 protected: 3591 G1CollectedHeap* _g1h; 3592 G1ParScanThreadStateSet* _per_thread_states; 3593 RefToScanQueueSet* _task_queues; 3594 TaskTerminator _terminator; 3595 uint _num_workers; 3596 3597 void evacuate_live_objects(G1ParScanThreadState* pss, 3598 uint worker_id, 3599 G1GCPhaseTimes::GCParPhases objcopy_phase, 3600 G1GCPhaseTimes::GCParPhases termination_phase) { 3601 G1GCPhaseTimes* p = _g1h->phase_times(); 3602 3603 Ticks start = Ticks::now(); 3604 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase); 3605 cl.do_void(); 3606 3607 assert(pss->queue_is_empty(), "should be empty"); 3608 3609 Tickspan evac_time = (Ticks::now() - start); 3610 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3611 3612 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste); 3613 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste); 3614 3615 if (termination_phase == G1GCPhaseTimes::Termination) { 3616 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3617 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3618 } else { 3619 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3620 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3621 } 3622 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3623 } 3624 3625 virtual void start_work(uint worker_id) { } 3626 3627 virtual void end_work(uint worker_id) { } 3628 3629 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3630 3631 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3632 3633 public: 3634 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3635 AbstractGangTask(name), 3636 _g1h(G1CollectedHeap::heap()), 3637 _per_thread_states(per_thread_states), 3638 _task_queues(task_queues), 3639 _terminator(num_workers, _task_queues), 3640 _num_workers(num_workers) 3641 { } 3642 3643 void work(uint worker_id) { 3644 start_work(worker_id); 3645 3646 { 3647 ResourceMark rm; 3648 HandleMark hm; 3649 3650 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3651 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3652 3653 scan_roots(pss, worker_id); 3654 evacuate_live_objects(pss, worker_id); 3655 } 3656 3657 end_work(worker_id); 3658 } 3659 }; 3660 3661 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3662 G1RootProcessor* _root_processor; 3663 3664 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3665 _root_processor->evacuate_roots(pss, worker_id); 3666 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3667 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3668 } 3669 3670 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3671 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3672 } 3673 3674 void start_work(uint worker_id) { 3675 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3676 } 3677 3678 void end_work(uint worker_id) { 3679 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3680 } 3681 3682 public: 3683 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3684 G1ParScanThreadStateSet* per_thread_states, 3685 RefToScanQueueSet* task_queues, 3686 G1RootProcessor* root_processor, 3687 uint num_workers) : 3688 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3689 _root_processor(root_processor) 3690 { } 3691 }; 3692 3693 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3694 G1GCPhaseTimes* p = phase_times(); 3695 3696 { 3697 Ticks start = Ticks::now(); 3698 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3699 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3700 } 3701 3702 Tickspan task_time; 3703 const uint num_workers = workers()->active_workers(); 3704 3705 Ticks start_processing = Ticks::now(); 3706 { 3707 G1RootProcessor root_processor(this, num_workers); 3708 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3709 task_time = run_task(&g1_par_task); 3710 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3711 // To extract its code root fixup time we measure total time of this scope and 3712 // subtract from the time the WorkGang task took. 3713 } 3714 Tickspan total_processing = Ticks::now() - start_processing; 3715 3716 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3717 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3718 } 3719 3720 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3721 3722 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3723 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3724 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3725 } 3726 3727 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3728 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3729 } 3730 3731 public: 3732 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3733 RefToScanQueueSet* queues, 3734 uint num_workers) : 3735 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3736 } 3737 }; 3738 3739 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3740 class G1MarkScope : public MarkScope { }; 3741 3742 Tickspan task_time; 3743 3744 Ticks start_processing = Ticks::now(); 3745 { 3746 G1MarkScope code_mark_scope; 3747 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3748 task_time = run_task(&task); 3749 // See comment in evacuate_collection_set() for the reason of the scope. 3750 } 3751 Tickspan total_processing = Ticks::now() - start_processing; 3752 3753 G1GCPhaseTimes* p = phase_times(); 3754 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3755 } 3756 3757 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3758 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3759 3760 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3761 3762 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3763 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3764 3765 if (time_left_ms < 0 || 3766 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3767 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3768 _collection_set.optional_region_length(), time_left_ms); 3769 break; 3770 } 3771 3772 { 3773 Ticks start = Ticks::now(); 3774 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3775 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3776 } 3777 3778 { 3779 Ticks start = Ticks::now(); 3780 evacuate_next_optional_regions(per_thread_states); 3781 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3782 } 3783 } 3784 3785 _collection_set.abandon_optional_collection_set(per_thread_states); 3786 } 3787 3788 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3789 G1RedirtyCardsQueueSet* rdcqs, 3790 G1ParScanThreadStateSet* per_thread_states) { 3791 rem_set()->cleanup_after_scan_heap_roots(); 3792 3793 // Process any discovered reference objects - we have 3794 // to do this _before_ we retire the GC alloc regions 3795 // as we may have to copy some 'reachable' referent 3796 // objects (and their reachable sub-graphs) that were 3797 // not copied during the pause. 3798 process_discovered_references(per_thread_states); 3799 3800 G1STWIsAliveClosure is_alive(this); 3801 G1KeepAliveClosure keep_alive(this); 3802 3803 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3804 phase_times()->weak_phase_times()); 3805 3806 if (G1StringDedup::is_enabled()) { 3807 double string_dedup_time_ms = os::elapsedTime(); 3808 3809 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3810 3811 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3812 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3813 } 3814 3815 _allocator->release_gc_alloc_regions(evacuation_info); 3816 3817 if (evacuation_failed()) { 3818 restore_after_evac_failure(rdcqs); 3819 3820 // Reset the G1EvacuationFailureALot counters and flags 3821 NOT_PRODUCT(reset_evacuation_should_fail();) 3822 3823 double recalculate_used_start = os::elapsedTime(); 3824 set_used(recalculate_used()); 3825 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3826 3827 if (_archive_allocator != NULL) { 3828 _archive_allocator->clear_used(); 3829 } 3830 for (uint i = 0; i < ParallelGCThreads; i++) { 3831 if (_evacuation_failed_info_array[i].has_failed()) { 3832 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3833 } 3834 } 3835 } else { 3836 // The "used" of the the collection set have already been subtracted 3837 // when they were freed. Add in the bytes evacuated. 3838 increase_used(policy()->bytes_copied_during_gc()); 3839 } 3840 3841 _preserved_marks_set.assert_empty(); 3842 3843 merge_per_thread_state_info(per_thread_states); 3844 3845 // Reset and re-enable the hot card cache. 3846 // Note the counts for the cards in the regions in the 3847 // collection set are reset when the collection set is freed. 3848 _hot_card_cache->reset_hot_cache(); 3849 _hot_card_cache->set_use_cache(true); 3850 3851 purge_code_root_memory(); 3852 3853 redirty_logged_cards(rdcqs); 3854 3855 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3856 3857 eagerly_reclaim_humongous_regions(); 3858 3859 record_obj_copy_mem_stats(); 3860 3861 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3862 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3863 3864 #if COMPILER2_OR_JVMCI 3865 double start = os::elapsedTime(); 3866 DerivedPointerTable::update_pointers(); 3867 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3868 #endif 3869 policy()->print_age_table(); 3870 } 3871 3872 void G1CollectedHeap::record_obj_copy_mem_stats() { 3873 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3874 3875 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3876 create_g1_evac_summary(&_old_evac_stats)); 3877 } 3878 3879 void G1CollectedHeap::free_region(HeapRegion* hr, 3880 FreeRegionList* free_list, 3881 bool skip_remset, 3882 bool skip_hot_card_cache, 3883 bool locked) { 3884 assert(!hr->is_free(), "the region should not be free"); 3885 assert(!hr->is_empty(), "the region should not be empty"); 3886 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3887 assert(free_list != NULL, "pre-condition"); 3888 3889 if (G1VerifyBitmaps) { 3890 MemRegion mr(hr->bottom(), hr->end()); 3891 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3892 } 3893 3894 // Clear the card counts for this region. 3895 // Note: we only need to do this if the region is not young 3896 // (since we don't refine cards in young regions). 3897 if (!skip_hot_card_cache && !hr->is_young()) { 3898 _hot_card_cache->reset_card_counts(hr); 3899 } 3900 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3901 _policy->remset_tracker()->update_at_free(hr); 3902 free_list->add_ordered(hr); 3903 } 3904 3905 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3906 FreeRegionList* free_list) { 3907 assert(hr->is_humongous(), "this is only for humongous regions"); 3908 assert(free_list != NULL, "pre-condition"); 3909 hr->clear_humongous(); 3910 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3911 } 3912 3913 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3914 const uint humongous_regions_removed) { 3915 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3916 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3917 _old_set.bulk_remove(old_regions_removed); 3918 _humongous_set.bulk_remove(humongous_regions_removed); 3919 } 3920 3921 } 3922 3923 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3924 assert(list != NULL, "list can't be null"); 3925 if (!list->is_empty()) { 3926 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3927 _hrm->insert_list_into_free_list(list); 3928 } 3929 } 3930 3931 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3932 decrease_used(bytes); 3933 } 3934 3935 class G1FreeCollectionSetTask : public AbstractGangTask { 3936 private: 3937 3938 // Closure applied to all regions in the collection set to do work that needs to 3939 // be done serially in a single thread. 3940 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3941 private: 3942 G1EvacuationInfo* _evacuation_info; 3943 const size_t* _surviving_young_words; 3944 3945 // Bytes used in successfully evacuated regions before the evacuation. 3946 size_t _before_used_bytes; 3947 // Bytes used in unsucessfully evacuated regions before the evacuation 3948 size_t _after_used_bytes; 3949 3950 size_t _bytes_allocated_in_old_since_last_gc; 3951 3952 size_t _failure_used_words; 3953 size_t _failure_waste_words; 3954 3955 FreeRegionList _local_free_list; 3956 public: 3957 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3958 HeapRegionClosure(), 3959 _evacuation_info(evacuation_info), 3960 _surviving_young_words(surviving_young_words), 3961 _before_used_bytes(0), 3962 _after_used_bytes(0), 3963 _bytes_allocated_in_old_since_last_gc(0), 3964 _failure_used_words(0), 3965 _failure_waste_words(0), 3966 _local_free_list("Local Region List for CSet Freeing") { 3967 } 3968 3969 virtual bool do_heap_region(HeapRegion* r) { 3970 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3971 3972 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3973 g1h->clear_region_attr(r); 3974 3975 if (r->is_young()) { 3976 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(), 3977 "Young index %u is wrong for region %u of type %s with %u young regions", 3978 r->young_index_in_cset(), 3979 r->hrm_index(), 3980 r->get_type_str(), 3981 g1h->collection_set()->young_region_length()); 3982 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 3983 r->record_surv_words_in_group(words_survived); 3984 } 3985 3986 if (!r->evacuation_failed()) { 3987 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 3988 _before_used_bytes += r->used(); 3989 g1h->free_region(r, 3990 &_local_free_list, 3991 true, /* skip_remset */ 3992 true, /* skip_hot_card_cache */ 3993 true /* locked */); 3994 } else { 3995 r->uninstall_surv_rate_group(); 3996 r->clear_young_index_in_cset(); 3997 r->set_evacuation_failed(false); 3998 // When moving a young gen region to old gen, we "allocate" that whole region 3999 // there. This is in addition to any already evacuated objects. Notify the 4000 // policy about that. 4001 // Old gen regions do not cause an additional allocation: both the objects 4002 // still in the region and the ones already moved are accounted for elsewhere. 4003 if (r->is_young()) { 4004 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4005 } 4006 // The region is now considered to be old. 4007 r->set_old(); 4008 // Do some allocation statistics accounting. Regions that failed evacuation 4009 // are always made old, so there is no need to update anything in the young 4010 // gen statistics, but we need to update old gen statistics. 4011 size_t used_words = r->marked_bytes() / HeapWordSize; 4012 4013 _failure_used_words += used_words; 4014 _failure_waste_words += HeapRegion::GrainWords - used_words; 4015 4016 g1h->old_set_add(r); 4017 _after_used_bytes += r->used(); 4018 } 4019 return false; 4020 } 4021 4022 void complete_work() { 4023 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4024 4025 _evacuation_info->set_regions_freed(_local_free_list.length()); 4026 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4027 4028 g1h->prepend_to_freelist(&_local_free_list); 4029 g1h->decrement_summary_bytes(_before_used_bytes); 4030 4031 G1Policy* policy = g1h->policy(); 4032 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4033 4034 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4035 } 4036 }; 4037 4038 G1CollectionSet* _collection_set; 4039 G1SerialFreeCollectionSetClosure _cl; 4040 const size_t* _surviving_young_words; 4041 4042 size_t _rs_length; 4043 4044 volatile jint _serial_work_claim; 4045 4046 struct WorkItem { 4047 uint region_idx; 4048 bool is_young; 4049 bool evacuation_failed; 4050 4051 WorkItem(HeapRegion* r) { 4052 region_idx = r->hrm_index(); 4053 is_young = r->is_young(); 4054 evacuation_failed = r->evacuation_failed(); 4055 } 4056 }; 4057 4058 volatile size_t _parallel_work_claim; 4059 size_t _num_work_items; 4060 WorkItem* _work_items; 4061 4062 void do_serial_work() { 4063 // Need to grab the lock to be allowed to modify the old region list. 4064 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4065 _collection_set->iterate(&_cl); 4066 } 4067 4068 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4069 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4070 4071 HeapRegion* r = g1h->region_at(region_idx); 4072 assert(!g1h->is_on_master_free_list(r), "sanity"); 4073 4074 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length); 4075 4076 if (!is_young) { 4077 g1h->_hot_card_cache->reset_card_counts(r); 4078 } 4079 4080 if (!evacuation_failed) { 4081 r->rem_set()->clear_locked(); 4082 } 4083 } 4084 4085 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4086 private: 4087 size_t _cur_idx; 4088 WorkItem* _work_items; 4089 public: 4090 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4091 4092 virtual bool do_heap_region(HeapRegion* r) { 4093 _work_items[_cur_idx++] = WorkItem(r); 4094 return false; 4095 } 4096 }; 4097 4098 void prepare_work() { 4099 G1PrepareFreeCollectionSetClosure cl(_work_items); 4100 _collection_set->iterate(&cl); 4101 } 4102 4103 void complete_work() { 4104 _cl.complete_work(); 4105 4106 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4107 policy->record_max_rs_length(_rs_length); 4108 policy->cset_regions_freed(); 4109 } 4110 public: 4111 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4112 AbstractGangTask("G1 Free Collection Set"), 4113 _collection_set(collection_set), 4114 _cl(evacuation_info, surviving_young_words), 4115 _surviving_young_words(surviving_young_words), 4116 _rs_length(0), 4117 _serial_work_claim(0), 4118 _parallel_work_claim(0), 4119 _num_work_items(collection_set->region_length()), 4120 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4121 prepare_work(); 4122 } 4123 4124 ~G1FreeCollectionSetTask() { 4125 complete_work(); 4126 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4127 } 4128 4129 // Chunk size for work distribution. The chosen value has been determined experimentally 4130 // to be a good tradeoff between overhead and achievable parallelism. 4131 static uint chunk_size() { return 32; } 4132 4133 virtual void work(uint worker_id) { 4134 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4135 4136 // Claim serial work. 4137 if (_serial_work_claim == 0) { 4138 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4139 if (value == 0) { 4140 double serial_time = os::elapsedTime(); 4141 do_serial_work(); 4142 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4143 } 4144 } 4145 4146 // Start parallel work. 4147 double young_time = 0.0; 4148 bool has_young_time = false; 4149 double non_young_time = 0.0; 4150 bool has_non_young_time = false; 4151 4152 while (true) { 4153 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4154 size_t cur = end - chunk_size(); 4155 4156 if (cur >= _num_work_items) { 4157 break; 4158 } 4159 4160 EventGCPhaseParallel event; 4161 double start_time = os::elapsedTime(); 4162 4163 end = MIN2(end, _num_work_items); 4164 4165 for (; cur < end; cur++) { 4166 bool is_young = _work_items[cur].is_young; 4167 4168 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4169 4170 double end_time = os::elapsedTime(); 4171 double time_taken = end_time - start_time; 4172 if (is_young) { 4173 young_time += time_taken; 4174 has_young_time = true; 4175 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4176 } else { 4177 non_young_time += time_taken; 4178 has_non_young_time = true; 4179 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4180 } 4181 start_time = end_time; 4182 } 4183 } 4184 4185 if (has_young_time) { 4186 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4187 } 4188 if (has_non_young_time) { 4189 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4190 } 4191 } 4192 }; 4193 4194 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4195 _eden.clear(); 4196 4197 double free_cset_start_time = os::elapsedTime(); 4198 4199 { 4200 uint const num_regions = _collection_set.region_length(); 4201 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U); 4202 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4203 4204 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4205 4206 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4207 cl.name(), num_workers, num_regions); 4208 workers()->run_task(&cl, num_workers); 4209 } 4210 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4211 4212 collection_set->clear(); 4213 } 4214 4215 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4216 private: 4217 FreeRegionList* _free_region_list; 4218 HeapRegionSet* _proxy_set; 4219 uint _humongous_objects_reclaimed; 4220 uint _humongous_regions_reclaimed; 4221 size_t _freed_bytes; 4222 public: 4223 4224 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4225 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4226 } 4227 4228 virtual bool do_heap_region(HeapRegion* r) { 4229 if (!r->is_starts_humongous()) { 4230 return false; 4231 } 4232 4233 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4234 4235 oop obj = (oop)r->bottom(); 4236 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4237 4238 // The following checks whether the humongous object is live are sufficient. 4239 // The main additional check (in addition to having a reference from the roots 4240 // or the young gen) is whether the humongous object has a remembered set entry. 4241 // 4242 // A humongous object cannot be live if there is no remembered set for it 4243 // because: 4244 // - there can be no references from within humongous starts regions referencing 4245 // the object because we never allocate other objects into them. 4246 // (I.e. there are no intra-region references that may be missed by the 4247 // remembered set) 4248 // - as soon there is a remembered set entry to the humongous starts region 4249 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4250 // until the end of a concurrent mark. 4251 // 4252 // It is not required to check whether the object has been found dead by marking 4253 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4254 // all objects allocated during that time are considered live. 4255 // SATB marking is even more conservative than the remembered set. 4256 // So if at this point in the collection there is no remembered set entry, 4257 // nobody has a reference to it. 4258 // At the start of collection we flush all refinement logs, and remembered sets 4259 // are completely up-to-date wrt to references to the humongous object. 4260 // 4261 // Other implementation considerations: 4262 // - never consider object arrays at this time because they would pose 4263 // considerable effort for cleaning up the the remembered sets. This is 4264 // required because stale remembered sets might reference locations that 4265 // are currently allocated into. 4266 uint region_idx = r->hrm_index(); 4267 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4268 !r->rem_set()->is_empty()) { 4269 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", 4270 region_idx, 4271 (size_t)obj->size() * HeapWordSize, 4272 p2i(r->bottom()), 4273 r->rem_set()->occupied(), 4274 r->rem_set()->strong_code_roots_list_length(), 4275 next_bitmap->is_marked(r->bottom()), 4276 g1h->is_humongous_reclaim_candidate(region_idx), 4277 obj->is_typeArray() 4278 ); 4279 return false; 4280 } 4281 4282 guarantee(obj->is_typeArray(), 4283 "Only eagerly reclaiming type arrays is supported, but the object " 4284 PTR_FORMAT " is not.", p2i(r->bottom())); 4285 4286 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", 4287 region_idx, 4288 (size_t)obj->size() * HeapWordSize, 4289 p2i(r->bottom()), 4290 r->rem_set()->occupied(), 4291 r->rem_set()->strong_code_roots_list_length(), 4292 next_bitmap->is_marked(r->bottom()), 4293 g1h->is_humongous_reclaim_candidate(region_idx), 4294 obj->is_typeArray() 4295 ); 4296 4297 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4298 cm->humongous_object_eagerly_reclaimed(r); 4299 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4300 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4301 region_idx, 4302 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4303 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4304 _humongous_objects_reclaimed++; 4305 do { 4306 HeapRegion* next = g1h->next_region_in_humongous(r); 4307 _freed_bytes += r->used(); 4308 r->set_containing_set(NULL); 4309 _humongous_regions_reclaimed++; 4310 g1h->free_humongous_region(r, _free_region_list); 4311 r = next; 4312 } while (r != NULL); 4313 4314 return false; 4315 } 4316 4317 uint humongous_objects_reclaimed() { 4318 return _humongous_objects_reclaimed; 4319 } 4320 4321 uint humongous_regions_reclaimed() { 4322 return _humongous_regions_reclaimed; 4323 } 4324 4325 size_t bytes_freed() const { 4326 return _freed_bytes; 4327 } 4328 }; 4329 4330 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4331 assert_at_safepoint_on_vm_thread(); 4332 4333 if (!G1EagerReclaimHumongousObjects || 4334 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4335 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4336 return; 4337 } 4338 4339 double start_time = os::elapsedTime(); 4340 4341 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4342 4343 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4344 heap_region_iterate(&cl); 4345 4346 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4347 4348 G1HRPrinter* hrp = hr_printer(); 4349 if (hrp->is_active()) { 4350 FreeRegionListIterator iter(&local_cleanup_list); 4351 while (iter.more_available()) { 4352 HeapRegion* hr = iter.get_next(); 4353 hrp->cleanup(hr); 4354 } 4355 } 4356 4357 prepend_to_freelist(&local_cleanup_list); 4358 decrement_summary_bytes(cl.bytes_freed()); 4359 4360 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4361 cl.humongous_objects_reclaimed()); 4362 } 4363 4364 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4365 public: 4366 virtual bool do_heap_region(HeapRegion* r) { 4367 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4368 G1CollectedHeap::heap()->clear_region_attr(r); 4369 r->clear_young_index_in_cset(); 4370 return false; 4371 } 4372 }; 4373 4374 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4375 G1AbandonCollectionSetClosure cl; 4376 collection_set_iterate_all(&cl); 4377 4378 collection_set->clear(); 4379 collection_set->stop_incremental_building(); 4380 } 4381 4382 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4383 return _allocator->is_retained_old_region(hr); 4384 } 4385 4386 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4387 _eden.add(hr); 4388 _policy->set_region_eden(hr); 4389 } 4390 4391 #ifdef ASSERT 4392 4393 class NoYoungRegionsClosure: public HeapRegionClosure { 4394 private: 4395 bool _success; 4396 public: 4397 NoYoungRegionsClosure() : _success(true) { } 4398 bool do_heap_region(HeapRegion* r) { 4399 if (r->is_young()) { 4400 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4401 p2i(r->bottom()), p2i(r->end())); 4402 _success = false; 4403 } 4404 return false; 4405 } 4406 bool success() { return _success; } 4407 }; 4408 4409 bool G1CollectedHeap::check_young_list_empty() { 4410 bool ret = (young_regions_count() == 0); 4411 4412 NoYoungRegionsClosure closure; 4413 heap_region_iterate(&closure); 4414 ret = ret && closure.success(); 4415 4416 return ret; 4417 } 4418 4419 #endif // ASSERT 4420 4421 class TearDownRegionSetsClosure : public HeapRegionClosure { 4422 HeapRegionSet *_old_set; 4423 4424 public: 4425 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4426 4427 bool do_heap_region(HeapRegion* r) { 4428 if (r->is_old()) { 4429 _old_set->remove(r); 4430 } else if(r->is_young()) { 4431 r->uninstall_surv_rate_group(); 4432 } else { 4433 // We ignore free regions, we'll empty the free list afterwards. 4434 // We ignore humongous and archive regions, we're not tearing down these 4435 // sets. 4436 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4437 "it cannot be another type"); 4438 } 4439 return false; 4440 } 4441 4442 ~TearDownRegionSetsClosure() { 4443 assert(_old_set->is_empty(), "post-condition"); 4444 } 4445 }; 4446 4447 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4448 assert_at_safepoint_on_vm_thread(); 4449 4450 if (!free_list_only) { 4451 TearDownRegionSetsClosure cl(&_old_set); 4452 heap_region_iterate(&cl); 4453 4454 // Note that emptying the _young_list is postponed and instead done as 4455 // the first step when rebuilding the regions sets again. The reason for 4456 // this is that during a full GC string deduplication needs to know if 4457 // a collected region was young or old when the full GC was initiated. 4458 } 4459 _hrm->remove_all_free_regions(); 4460 } 4461 4462 void G1CollectedHeap::increase_used(size_t bytes) { 4463 _summary_bytes_used += bytes; 4464 } 4465 4466 void G1CollectedHeap::decrease_used(size_t bytes) { 4467 assert(_summary_bytes_used >= bytes, 4468 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4469 _summary_bytes_used, bytes); 4470 _summary_bytes_used -= bytes; 4471 } 4472 4473 void G1CollectedHeap::set_used(size_t bytes) { 4474 _summary_bytes_used = bytes; 4475 } 4476 4477 class RebuildRegionSetsClosure : public HeapRegionClosure { 4478 private: 4479 bool _free_list_only; 4480 4481 HeapRegionSet* _old_set; 4482 HeapRegionManager* _hrm; 4483 4484 size_t _total_used; 4485 4486 public: 4487 RebuildRegionSetsClosure(bool free_list_only, 4488 HeapRegionSet* old_set, 4489 HeapRegionManager* hrm) : 4490 _free_list_only(free_list_only), 4491 _old_set(old_set), _hrm(hrm), _total_used(0) { 4492 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4493 if (!free_list_only) { 4494 assert(_old_set->is_empty(), "pre-condition"); 4495 } 4496 } 4497 4498 bool do_heap_region(HeapRegion* r) { 4499 if (r->is_empty()) { 4500 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4501 // Add free regions to the free list 4502 r->set_free(); 4503 _hrm->insert_into_free_list(r); 4504 } else if (!_free_list_only) { 4505 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4506 4507 if (r->is_archive() || r->is_humongous()) { 4508 // We ignore archive and humongous regions. We left these sets unchanged. 4509 } else { 4510 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4511 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4512 r->move_to_old(); 4513 _old_set->add(r); 4514 } 4515 _total_used += r->used(); 4516 } 4517 4518 return false; 4519 } 4520 4521 size_t total_used() { 4522 return _total_used; 4523 } 4524 }; 4525 4526 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4527 assert_at_safepoint_on_vm_thread(); 4528 4529 if (!free_list_only) { 4530 _eden.clear(); 4531 _survivor.clear(); 4532 } 4533 4534 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4535 heap_region_iterate(&cl); 4536 4537 if (!free_list_only) { 4538 set_used(cl.total_used()); 4539 if (_archive_allocator != NULL) { 4540 _archive_allocator->clear_used(); 4541 } 4542 } 4543 assert_used_and_recalculate_used_equal(this); 4544 } 4545 4546 // Methods for the mutator alloc region 4547 4548 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4549 bool force) { 4550 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4551 bool should_allocate = policy()->should_allocate_mutator_region(); 4552 if (force || should_allocate) { 4553 HeapRegion* new_alloc_region = new_region(word_size, 4554 HeapRegionType::Eden, 4555 false /* do_expand */); 4556 if (new_alloc_region != NULL) { 4557 set_region_short_lived_locked(new_alloc_region); 4558 _hr_printer.alloc(new_alloc_region, !should_allocate); 4559 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4560 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4561 return new_alloc_region; 4562 } 4563 } 4564 return NULL; 4565 } 4566 4567 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4568 size_t allocated_bytes) { 4569 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4570 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4571 4572 collection_set()->add_eden_region(alloc_region); 4573 increase_used(allocated_bytes); 4574 _eden.add_used_bytes(allocated_bytes); 4575 _hr_printer.retire(alloc_region); 4576 4577 // We update the eden sizes here, when the region is retired, 4578 // instead of when it's allocated, since this is the point that its 4579 // used space has been recorded in _summary_bytes_used. 4580 g1mm()->update_eden_size(); 4581 } 4582 4583 // Methods for the GC alloc regions 4584 4585 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4586 if (dest.is_old()) { 4587 return true; 4588 } else { 4589 return survivor_regions_count() < policy()->max_survivor_regions(); 4590 } 4591 } 4592 4593 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) { 4594 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4595 4596 if (!has_more_regions(dest)) { 4597 return NULL; 4598 } 4599 4600 HeapRegionType type; 4601 if (dest.is_young()) { 4602 type = HeapRegionType::Survivor; 4603 } else { 4604 type = HeapRegionType::Old; 4605 } 4606 4607 HeapRegion* new_alloc_region = new_region(word_size, 4608 type, 4609 true /* do_expand */); 4610 4611 if (new_alloc_region != NULL) { 4612 if (type.is_survivor()) { 4613 new_alloc_region->set_survivor(); 4614 _survivor.add(new_alloc_region); 4615 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4616 } else { 4617 new_alloc_region->set_old(); 4618 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4619 } 4620 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4621 register_region_with_region_attr(new_alloc_region); 4622 _hr_printer.alloc(new_alloc_region); 4623 return new_alloc_region; 4624 } 4625 return NULL; 4626 } 4627 4628 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4629 size_t allocated_bytes, 4630 G1HeapRegionAttr dest) { 4631 policy()->record_bytes_copied_during_gc(allocated_bytes); 4632 if (dest.is_old()) { 4633 old_set_add(alloc_region); 4634 } else { 4635 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4636 _survivor.add_used_bytes(allocated_bytes); 4637 } 4638 4639 bool const during_im = collector_state()->in_initial_mark_gc(); 4640 if (during_im && allocated_bytes > 0) { 4641 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4642 } 4643 _hr_printer.retire(alloc_region); 4644 } 4645 4646 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4647 bool expanded = false; 4648 uint index = _hrm->find_highest_free(&expanded); 4649 4650 if (index != G1_NO_HRM_INDEX) { 4651 if (expanded) { 4652 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4653 HeapRegion::GrainWords * HeapWordSize); 4654 } 4655 _hrm->allocate_free_regions_starting_at(index, 1); 4656 return region_at(index); 4657 } 4658 return NULL; 4659 } 4660 4661 // Optimized nmethod scanning 4662 4663 class RegisterNMethodOopClosure: public OopClosure { 4664 G1CollectedHeap* _g1h; 4665 nmethod* _nm; 4666 4667 template <class T> void do_oop_work(T* p) { 4668 T heap_oop = RawAccess<>::oop_load(p); 4669 if (!CompressedOops::is_null(heap_oop)) { 4670 oop obj = CompressedOops::decode_not_null(heap_oop); 4671 HeapRegion* hr = _g1h->heap_region_containing(obj); 4672 assert(!hr->is_continues_humongous(), 4673 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4674 " starting at " HR_FORMAT, 4675 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4676 4677 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4678 hr->add_strong_code_root_locked(_nm); 4679 } 4680 } 4681 4682 public: 4683 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4684 _g1h(g1h), _nm(nm) {} 4685 4686 void do_oop(oop* p) { do_oop_work(p); } 4687 void do_oop(narrowOop* p) { do_oop_work(p); } 4688 }; 4689 4690 class UnregisterNMethodOopClosure: public OopClosure { 4691 G1CollectedHeap* _g1h; 4692 nmethod* _nm; 4693 4694 template <class T> void do_oop_work(T* p) { 4695 T heap_oop = RawAccess<>::oop_load(p); 4696 if (!CompressedOops::is_null(heap_oop)) { 4697 oop obj = CompressedOops::decode_not_null(heap_oop); 4698 HeapRegion* hr = _g1h->heap_region_containing(obj); 4699 assert(!hr->is_continues_humongous(), 4700 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4701 " starting at " HR_FORMAT, 4702 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4703 4704 hr->remove_strong_code_root(_nm); 4705 } 4706 } 4707 4708 public: 4709 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4710 _g1h(g1h), _nm(nm) {} 4711 4712 void do_oop(oop* p) { do_oop_work(p); } 4713 void do_oop(narrowOop* p) { do_oop_work(p); } 4714 }; 4715 4716 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4717 guarantee(nm != NULL, "sanity"); 4718 RegisterNMethodOopClosure reg_cl(this, nm); 4719 nm->oops_do(®_cl); 4720 } 4721 4722 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4723 guarantee(nm != NULL, "sanity"); 4724 UnregisterNMethodOopClosure reg_cl(this, nm); 4725 nm->oops_do(®_cl, true); 4726 } 4727 4728 void G1CollectedHeap::purge_code_root_memory() { 4729 double purge_start = os::elapsedTime(); 4730 G1CodeRootSet::purge(); 4731 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4732 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4733 } 4734 4735 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4736 G1CollectedHeap* _g1h; 4737 4738 public: 4739 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4740 _g1h(g1h) {} 4741 4742 void do_code_blob(CodeBlob* cb) { 4743 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4744 if (nm == NULL) { 4745 return; 4746 } 4747 4748 _g1h->register_nmethod(nm); 4749 } 4750 }; 4751 4752 void G1CollectedHeap::rebuild_strong_code_roots() { 4753 RebuildStrongCodeRootClosure blob_cl(this); 4754 CodeCache::blobs_do(&blob_cl); 4755 } 4756 4757 void G1CollectedHeap::initialize_serviceability() { 4758 _g1mm->initialize_serviceability(); 4759 } 4760 4761 MemoryUsage G1CollectedHeap::memory_usage() { 4762 return _g1mm->memory_usage(); 4763 } 4764 4765 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4766 return _g1mm->memory_managers(); 4767 } 4768 4769 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4770 return _g1mm->memory_pools(); 4771 }