1 /* 2 * Copyright (c) 2001, 2020, 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/g1GCParPhaseTimesTracker.hpp" 45 #include "gc/g1/g1GCPhaseTimes.hpp" 46 #include "gc/g1/g1HeapSizingPolicy.hpp" 47 #include "gc/g1/g1HeapTransition.hpp" 48 #include "gc/g1/g1HeapVerifier.hpp" 49 #include "gc/g1/g1HotCardCache.hpp" 50 #include "gc/g1/g1InitLogger.hpp" 51 #include "gc/g1/g1MemoryPool.hpp" 52 #include "gc/g1/g1OopClosures.inline.hpp" 53 #include "gc/g1/g1ParallelCleaning.hpp" 54 #include "gc/g1/g1ParScanThreadState.inline.hpp" 55 #include "gc/g1/g1Policy.hpp" 56 #include "gc/g1/g1RedirtyCardsQueue.hpp" 57 #include "gc/g1/g1RegionToSpaceMapper.hpp" 58 #include "gc/g1/g1RemSet.hpp" 59 #include "gc/g1/g1RootClosures.hpp" 60 #include "gc/g1/g1RootProcessor.hpp" 61 #include "gc/g1/g1SATBMarkQueueSet.hpp" 62 #include "gc/g1/g1StringDedup.hpp" 63 #include "gc/g1/g1ThreadLocalData.hpp" 64 #include "gc/g1/g1Trace.hpp" 65 #include "gc/g1/g1YCTypes.hpp" 66 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 67 #include "gc/g1/g1VMOperations.hpp" 68 #include "gc/g1/heapRegion.inline.hpp" 69 #include "gc/g1/heapRegionRemSet.hpp" 70 #include "gc/g1/heapRegionSet.inline.hpp" 71 #include "gc/shared/concurrentGCBreakpoints.hpp" 72 #include "gc/shared/gcBehaviours.hpp" 73 #include "gc/shared/gcHeapSummary.hpp" 74 #include "gc/shared/gcId.hpp" 75 #include "gc/shared/gcLocker.hpp" 76 #include "gc/shared/gcTimer.hpp" 77 #include "gc/shared/gcTraceTime.inline.hpp" 78 #include "gc/shared/generationSpec.hpp" 79 #include "gc/shared/isGCActiveMark.hpp" 80 #include "gc/shared/locationPrinter.inline.hpp" 81 #include "gc/shared/oopStorageParState.hpp" 82 #include "gc/shared/preservedMarks.inline.hpp" 83 #include "gc/shared/suspendibleThreadSet.hpp" 84 #include "gc/shared/referenceProcessor.inline.hpp" 85 #include "gc/shared/taskTerminator.hpp" 86 #include "gc/shared/taskqueue.inline.hpp" 87 #include "gc/shared/weakProcessor.inline.hpp" 88 #include "gc/shared/workerPolicy.hpp" 89 #include "logging/log.hpp" 90 #include "memory/allocation.hpp" 91 #include "memory/iterator.hpp" 92 #include "memory/heapInspection.hpp" 93 #include "memory/resourceArea.hpp" 94 #include "memory/universe.hpp" 95 #include "oops/access.inline.hpp" 96 #include "oops/compressedOops.inline.hpp" 97 #include "oops/oop.inline.hpp" 98 #include "runtime/atomic.hpp" 99 #include "runtime/handles.inline.hpp" 100 #include "runtime/init.hpp" 101 #include "runtime/orderAccess.hpp" 102 #include "runtime/threadSMR.hpp" 103 #include "runtime/vmThread.hpp" 104 #include "utilities/align.hpp" 105 #include "utilities/autoRestore.hpp" 106 #include "utilities/bitMap.inline.hpp" 107 #include "utilities/globalDefinitions.hpp" 108 #include "utilities/stack.inline.hpp" 109 110 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 111 112 // INVARIANTS/NOTES 113 // 114 // All allocation activity covered by the G1CollectedHeap interface is 115 // serialized by acquiring the HeapLock. This happens in mem_allocate 116 // and allocate_new_tlab, which are the "entry" points to the 117 // allocation code from the rest of the JVM. (Note that this does not 118 // apply to TLAB allocation, which is not part of this interface: it 119 // is done by clients of this interface.) 120 121 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 122 private: 123 size_t _num_dirtied; 124 G1CollectedHeap* _g1h; 125 G1CardTable* _g1_ct; 126 127 HeapRegion* region_for_card(CardValue* card_ptr) const { 128 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 129 } 130 131 bool will_become_free(HeapRegion* hr) const { 132 // A region will be freed by free_collection_set if the region is in the 133 // collection set and has not had an evacuation failure. 134 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 135 } 136 137 public: 138 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 139 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 140 141 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 142 HeapRegion* hr = region_for_card(card_ptr); 143 144 // Should only dirty cards in regions that won't be freed. 145 if (!will_become_free(hr)) { 146 *card_ptr = G1CardTable::dirty_card_val(); 147 _num_dirtied++; 148 } 149 } 150 151 size_t num_dirtied() const { return _num_dirtied; } 152 }; 153 154 155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 156 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 157 } 158 159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 160 // The from card cache is not the memory that is actually committed. So we cannot 161 // take advantage of the zero_filled parameter. 162 reset_from_card_cache(start_idx, num_regions); 163 } 164 165 void G1CollectedHeap::run_task(AbstractGangTask* task) { 166 workers()->run_task(task, workers()->active_workers()); 167 } 168 169 Tickspan G1CollectedHeap::run_task_timed(AbstractGangTask* task) { 170 Ticks start = Ticks::now(); 171 run_task(task); 172 return Ticks::now() - start; 173 } 174 175 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 176 MemRegion mr) { 177 return new HeapRegion(hrs_index, bot(), mr); 178 } 179 180 // Private methods. 181 182 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 183 HeapRegionType type, 184 bool do_expand, 185 uint node_index) { 186 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 187 "the only time we use this to allocate a humongous region is " 188 "when we are allocating a single humongous region"); 189 190 HeapRegion* res = _hrm->allocate_free_region(type, node_index); 191 192 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 193 // Currently, only attempts to allocate GC alloc regions set 194 // do_expand to true. So, we should only reach here during a 195 // safepoint. If this assumption changes we might have to 196 // reconsider the use of _expand_heap_after_alloc_failure. 197 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 198 199 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 200 word_size * HeapWordSize); 201 202 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 203 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 204 word_size * HeapWordSize); 205 if (expand_single_region(node_index)) { 206 // Given that expand_single_region() succeeded in expanding the heap, and we 207 // always expand the heap by an amount aligned to the heap 208 // region size, the free list should in theory not be empty. 209 // In either case allocate_free_region() will check for NULL. 210 res = _hrm->allocate_free_region(type, node_index); 211 } else { 212 _expand_heap_after_alloc_failure = false; 213 } 214 } 215 return res; 216 } 217 218 HeapWord* 219 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 220 uint num_regions, 221 size_t word_size) { 222 assert(first_hr != NULL, "pre-condition"); 223 assert(is_humongous(word_size), "word_size should be humongous"); 224 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 225 226 // Index of last region in the series. 227 uint first = first_hr->hrm_index(); 228 uint last = first + num_regions - 1; 229 230 // We need to initialize the region(s) we just discovered. This is 231 // a bit tricky given that it can happen concurrently with 232 // refinement threads refining cards on these regions and 233 // potentially wanting to refine the BOT as they are scanning 234 // those cards (this can happen shortly after a cleanup; see CR 235 // 6991377). So we have to set up the region(s) carefully and in 236 // a specific order. 237 238 // The word size sum of all the regions we will allocate. 239 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 240 assert(word_size <= word_size_sum, "sanity"); 241 242 // The passed in hr will be the "starts humongous" region. The header 243 // of the new object will be placed at the bottom of this region. 244 HeapWord* new_obj = first_hr->bottom(); 245 // This will be the new top of the new object. 246 HeapWord* obj_top = new_obj + word_size; 247 248 // First, we need to zero the header of the space that we will be 249 // allocating. When we update top further down, some refinement 250 // threads might try to scan the region. By zeroing the header we 251 // ensure that any thread that will try to scan the region will 252 // come across the zero klass word and bail out. 253 // 254 // NOTE: It would not have been correct to have used 255 // CollectedHeap::fill_with_object() and make the space look like 256 // an int array. The thread that is doing the allocation will 257 // later update the object header to a potentially different array 258 // type and, for a very short period of time, the klass and length 259 // fields will be inconsistent. This could cause a refinement 260 // thread to calculate the object size incorrectly. 261 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 262 263 // Next, pad out the unused tail of the last region with filler 264 // objects, for improved usage accounting. 265 // How many words we use for filler objects. 266 size_t word_fill_size = word_size_sum - word_size; 267 268 // How many words memory we "waste" which cannot hold a filler object. 269 size_t words_not_fillable = 0; 270 271 if (word_fill_size >= min_fill_size()) { 272 fill_with_objects(obj_top, word_fill_size); 273 } else if (word_fill_size > 0) { 274 // We have space to fill, but we cannot fit an object there. 275 words_not_fillable = word_fill_size; 276 word_fill_size = 0; 277 } 278 279 // We will set up the first region as "starts humongous". This 280 // will also update the BOT covering all the regions to reflect 281 // that there is a single object that starts at the bottom of the 282 // first region. 283 first_hr->set_starts_humongous(obj_top, word_fill_size); 284 _policy->remset_tracker()->update_at_allocate(first_hr); 285 // Then, if there are any, we will set up the "continues 286 // humongous" regions. 287 HeapRegion* hr = NULL; 288 for (uint i = first + 1; i <= last; ++i) { 289 hr = region_at(i); 290 hr->set_continues_humongous(first_hr); 291 _policy->remset_tracker()->update_at_allocate(hr); 292 } 293 294 // Up to this point no concurrent thread would have been able to 295 // do any scanning on any region in this series. All the top 296 // fields still point to bottom, so the intersection between 297 // [bottom,top] and [card_start,card_end] will be empty. Before we 298 // update the top fields, we'll do a storestore to make sure that 299 // no thread sees the update to top before the zeroing of the 300 // object header and the BOT initialization. 301 OrderAccess::storestore(); 302 303 // Now, we will update the top fields of the "continues humongous" 304 // regions except the last one. 305 for (uint i = first; i < last; ++i) { 306 hr = region_at(i); 307 hr->set_top(hr->end()); 308 } 309 310 hr = region_at(last); 311 // If we cannot fit a filler object, we must set top to the end 312 // of the humongous object, otherwise we cannot iterate the heap 313 // and the BOT will not be complete. 314 hr->set_top(hr->end() - words_not_fillable); 315 316 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 317 "obj_top should be in last region"); 318 319 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 320 321 assert(words_not_fillable == 0 || 322 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 323 "Miscalculation in humongous allocation"); 324 325 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 326 327 for (uint i = first; i <= last; ++i) { 328 hr = region_at(i); 329 _humongous_set.add(hr); 330 _hr_printer.alloc(hr); 331 } 332 333 return new_obj; 334 } 335 336 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 337 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 338 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 339 } 340 341 // If could fit into free regions w/o expansion, try. 342 // Otherwise, if can expand, do so. 343 // Otherwise, if using ex regions might help, try with ex given back. 344 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 345 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 346 347 _verifier->verify_region_sets_optional(); 348 349 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 350 351 // Policy: First try to allocate a humongous object in the free list. 352 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions); 353 if (humongous_start == NULL) { 354 // Policy: We could not find enough regions for the humongous object in the 355 // free list. Look through the heap to find a mix of free and uncommitted regions. 356 // If so, expand the heap and allocate the humongous object. 357 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions); 358 if (humongous_start != NULL) { 359 // We managed to find a region by expanding the heap. 360 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B", 361 word_size * HeapWordSize); 362 policy()->record_new_heap_size(num_regions()); 363 } else { 364 // Policy: Potentially trigger a defragmentation GC. 365 } 366 } 367 368 HeapWord* result = NULL; 369 if (humongous_start != NULL) { 370 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size); 371 assert(result != NULL, "it should always return a valid result"); 372 373 // A successful humongous object allocation changes the used space 374 // information of the old generation so we need to recalculate the 375 // sizes and update the jstat counters here. 376 g1mm()->update_sizes(); 377 } 378 379 _verifier->verify_region_sets_optional(); 380 381 return result; 382 } 383 384 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 385 size_t requested_size, 386 size_t* actual_size) { 387 assert_heap_not_locked_and_not_at_safepoint(); 388 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 389 390 return attempt_allocation(min_size, requested_size, actual_size); 391 } 392 393 HeapWord* 394 G1CollectedHeap::mem_allocate(size_t word_size, 395 bool* gc_overhead_limit_was_exceeded) { 396 assert_heap_not_locked_and_not_at_safepoint(); 397 398 if (is_humongous(word_size)) { 399 return attempt_allocation_humongous(word_size); 400 } 401 size_t dummy = 0; 402 return attempt_allocation(word_size, word_size, &dummy); 403 } 404 405 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 406 ResourceMark rm; // For retrieving the thread names in log messages. 407 408 // Make sure you read the note in attempt_allocation_humongous(). 409 410 assert_heap_not_locked_and_not_at_safepoint(); 411 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 412 "be called for humongous allocation requests"); 413 414 // We should only get here after the first-level allocation attempt 415 // (attempt_allocation()) failed to allocate. 416 417 // We will loop until a) we manage to successfully perform the 418 // allocation or b) we successfully schedule a collection which 419 // fails to perform the allocation. b) is the only case when we'll 420 // return NULL. 421 HeapWord* result = NULL; 422 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 423 bool should_try_gc; 424 uint gc_count_before; 425 426 { 427 MutexLocker x(Heap_lock); 428 result = _allocator->attempt_allocation_locked(word_size); 429 if (result != NULL) { 430 return result; 431 } 432 433 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 434 // This is different to when only GCLocker::needs_gc() is set: try to avoid 435 // waiting because the GCLocker is active to not wait too long. 436 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 437 // No need for an ergo message here, can_expand_young_list() does this when 438 // it returns true. 439 result = _allocator->attempt_allocation_force(word_size); 440 if (result != NULL) { 441 return result; 442 } 443 } 444 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 445 // the GCLocker initiated GC has been performed and then retry. This includes 446 // the case when the GC Locker is not active but has not been performed. 447 should_try_gc = !GCLocker::needs_gc(); 448 // Read the GC count while still holding the Heap_lock. 449 gc_count_before = total_collections(); 450 } 451 452 if (should_try_gc) { 453 bool succeeded; 454 result = do_collection_pause(word_size, gc_count_before, &succeeded, 455 GCCause::_g1_inc_collection_pause); 456 if (result != NULL) { 457 assert(succeeded, "only way to get back a non-NULL result"); 458 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 459 Thread::current()->name(), p2i(result)); 460 return result; 461 } 462 463 if (succeeded) { 464 // We successfully scheduled a collection which failed to allocate. No 465 // point in trying to allocate further. We'll just return NULL. 466 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 467 SIZE_FORMAT " words", Thread::current()->name(), word_size); 468 return NULL; 469 } 470 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 471 Thread::current()->name(), word_size); 472 } else { 473 // Failed to schedule a collection. 474 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 475 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 476 SIZE_FORMAT " words", Thread::current()->name(), word_size); 477 return NULL; 478 } 479 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 480 // The GCLocker is either active or the GCLocker initiated 481 // GC has not yet been performed. Stall until it is and 482 // then retry the allocation. 483 GCLocker::stall_until_clear(); 484 gclocker_retry_count += 1; 485 } 486 487 // We can reach here if we were unsuccessful in scheduling a 488 // collection (because another thread beat us to it) or if we were 489 // stalled due to the GC locker. In either can we should retry the 490 // allocation attempt in case another thread successfully 491 // performed a collection and reclaimed enough space. We do the 492 // first attempt (without holding the Heap_lock) here and the 493 // follow-on attempt will be at the start of the next loop 494 // iteration (after taking the Heap_lock). 495 size_t dummy = 0; 496 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 497 if (result != NULL) { 498 return result; 499 } 500 501 // Give a warning if we seem to be looping forever. 502 if ((QueuedAllocationWarningCount > 0) && 503 (try_count % QueuedAllocationWarningCount == 0)) { 504 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 505 Thread::current()->name(), try_count, word_size); 506 } 507 } 508 509 ShouldNotReachHere(); 510 return NULL; 511 } 512 513 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 514 assert_at_safepoint_on_vm_thread(); 515 if (_archive_allocator == NULL) { 516 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 517 } 518 } 519 520 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 521 // Allocations in archive regions cannot be of a size that would be considered 522 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 523 // may be different at archive-restore time. 524 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 525 } 526 527 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 528 assert_at_safepoint_on_vm_thread(); 529 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 530 if (is_archive_alloc_too_large(word_size)) { 531 return NULL; 532 } 533 return _archive_allocator->archive_mem_allocate(word_size); 534 } 535 536 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 537 size_t end_alignment_in_bytes) { 538 assert_at_safepoint_on_vm_thread(); 539 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 540 541 // Call complete_archive to do the real work, filling in the MemRegion 542 // array with the archive regions. 543 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 544 delete _archive_allocator; 545 _archive_allocator = NULL; 546 } 547 548 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 549 assert(ranges != NULL, "MemRegion array NULL"); 550 assert(count != 0, "No MemRegions provided"); 551 MemRegion reserved = _hrm->reserved(); 552 for (size_t i = 0; i < count; i++) { 553 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 554 return false; 555 } 556 } 557 return true; 558 } 559 560 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 561 size_t count, 562 bool open) { 563 assert(!is_init_completed(), "Expect to be called at JVM init time"); 564 assert(ranges != NULL, "MemRegion array NULL"); 565 assert(count != 0, "No MemRegions provided"); 566 MutexLocker x(Heap_lock); 567 568 MemRegion reserved = _hrm->reserved(); 569 HeapWord* prev_last_addr = NULL; 570 HeapRegion* prev_last_region = NULL; 571 572 // Temporarily disable pretouching of heap pages. This interface is used 573 // when mmap'ing archived heap data in, so pre-touching is wasted. 574 FlagSetting fs(AlwaysPreTouch, false); 575 576 // Enable archive object checking used by G1MarkSweep. We have to let it know 577 // about each archive range, so that objects in those ranges aren't marked. 578 G1ArchiveAllocator::enable_archive_object_check(); 579 580 // For each specified MemRegion range, allocate the corresponding G1 581 // regions and mark them as archive regions. We expect the ranges 582 // in ascending starting address order, without overlap. 583 for (size_t i = 0; i < count; i++) { 584 MemRegion curr_range = ranges[i]; 585 HeapWord* start_address = curr_range.start(); 586 size_t word_size = curr_range.word_size(); 587 HeapWord* last_address = curr_range.last(); 588 size_t commits = 0; 589 590 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 591 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 592 p2i(start_address), p2i(last_address)); 593 guarantee(start_address > prev_last_addr, 594 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 595 p2i(start_address), p2i(prev_last_addr)); 596 prev_last_addr = last_address; 597 598 // Check for ranges that start in the same G1 region in which the previous 599 // range ended, and adjust the start address so we don't try to allocate 600 // the same region again. If the current range is entirely within that 601 // region, skip it, just adjusting the recorded top. 602 HeapRegion* start_region = _hrm->addr_to_region(start_address); 603 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 604 start_address = start_region->end(); 605 if (start_address > last_address) { 606 increase_used(word_size * HeapWordSize); 607 start_region->set_top(last_address + 1); 608 continue; 609 } 610 start_region->set_top(start_address); 611 curr_range = MemRegion(start_address, last_address + 1); 612 start_region = _hrm->addr_to_region(start_address); 613 } 614 615 // Perform the actual region allocation, exiting if it fails. 616 // Then note how much new space we have allocated. 617 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 618 return false; 619 } 620 increase_used(word_size * HeapWordSize); 621 if (commits != 0) { 622 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 623 HeapRegion::GrainWords * HeapWordSize * commits); 624 625 } 626 627 // Mark each G1 region touched by the range as archive, add it to 628 // the old set, and set top. 629 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 630 HeapRegion* last_region = _hrm->addr_to_region(last_address); 631 prev_last_region = last_region; 632 633 while (curr_region != NULL) { 634 assert(curr_region->is_empty() && !curr_region->is_pinned(), 635 "Region already in use (index %u)", curr_region->hrm_index()); 636 if (open) { 637 curr_region->set_open_archive(); 638 } else { 639 curr_region->set_closed_archive(); 640 } 641 _hr_printer.alloc(curr_region); 642 _archive_set.add(curr_region); 643 HeapWord* top; 644 HeapRegion* next_region; 645 if (curr_region != last_region) { 646 top = curr_region->end(); 647 next_region = _hrm->next_region_in_heap(curr_region); 648 } else { 649 top = last_address + 1; 650 next_region = NULL; 651 } 652 curr_region->set_top(top); 653 curr_region = next_region; 654 } 655 656 // Notify mark-sweep of the archive 657 G1ArchiveAllocator::set_range_archive(curr_range, open); 658 } 659 return true; 660 } 661 662 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 663 assert(!is_init_completed(), "Expect to be called at JVM init time"); 664 assert(ranges != NULL, "MemRegion array NULL"); 665 assert(count != 0, "No MemRegions provided"); 666 MemRegion reserved = _hrm->reserved(); 667 HeapWord *prev_last_addr = NULL; 668 HeapRegion* prev_last_region = NULL; 669 670 // For each MemRegion, create filler objects, if needed, in the G1 regions 671 // that contain the address range. The address range actually within the 672 // MemRegion will not be modified. That is assumed to have been initialized 673 // elsewhere, probably via an mmap of archived heap data. 674 MutexLocker x(Heap_lock); 675 for (size_t i = 0; i < count; i++) { 676 HeapWord* start_address = ranges[i].start(); 677 HeapWord* last_address = ranges[i].last(); 678 679 assert(reserved.contains(start_address) && reserved.contains(last_address), 680 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 681 p2i(start_address), p2i(last_address)); 682 assert(start_address > prev_last_addr, 683 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 684 p2i(start_address), p2i(prev_last_addr)); 685 686 HeapRegion* start_region = _hrm->addr_to_region(start_address); 687 HeapRegion* last_region = _hrm->addr_to_region(last_address); 688 HeapWord* bottom_address = start_region->bottom(); 689 690 // Check for a range beginning in the same region in which the 691 // previous one ended. 692 if (start_region == prev_last_region) { 693 bottom_address = prev_last_addr + 1; 694 } 695 696 // Verify that the regions were all marked as archive regions by 697 // alloc_archive_regions. 698 HeapRegion* curr_region = start_region; 699 while (curr_region != NULL) { 700 guarantee(curr_region->is_archive(), 701 "Expected archive region at index %u", curr_region->hrm_index()); 702 if (curr_region != last_region) { 703 curr_region = _hrm->next_region_in_heap(curr_region); 704 } else { 705 curr_region = NULL; 706 } 707 } 708 709 prev_last_addr = last_address; 710 prev_last_region = last_region; 711 712 // Fill the memory below the allocated range with dummy object(s), 713 // if the region bottom does not match the range start, or if the previous 714 // range ended within the same G1 region, and there is a gap. 715 if (start_address != bottom_address) { 716 size_t fill_size = pointer_delta(start_address, bottom_address); 717 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 718 increase_used(fill_size * HeapWordSize); 719 } 720 } 721 } 722 723 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 724 size_t desired_word_size, 725 size_t* actual_word_size) { 726 assert_heap_not_locked_and_not_at_safepoint(); 727 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 728 "be called for humongous allocation requests"); 729 730 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 731 732 if (result == NULL) { 733 *actual_word_size = desired_word_size; 734 result = attempt_allocation_slow(desired_word_size); 735 } 736 737 assert_heap_not_locked(); 738 if (result != NULL) { 739 assert(*actual_word_size != 0, "Actual size must have been set here"); 740 dirty_young_block(result, *actual_word_size); 741 } else { 742 *actual_word_size = 0; 743 } 744 745 return result; 746 } 747 748 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 749 assert(!is_init_completed(), "Expect to be called at JVM init time"); 750 assert(ranges != NULL, "MemRegion array NULL"); 751 assert(count != 0, "No MemRegions provided"); 752 MemRegion reserved = _hrm->reserved(); 753 HeapWord* prev_last_addr = NULL; 754 HeapRegion* prev_last_region = NULL; 755 size_t size_used = 0; 756 size_t uncommitted_regions = 0; 757 758 // For each Memregion, free the G1 regions that constitute it, and 759 // notify mark-sweep that the range is no longer to be considered 'archive.' 760 MutexLocker x(Heap_lock); 761 for (size_t i = 0; i < count; i++) { 762 HeapWord* start_address = ranges[i].start(); 763 HeapWord* last_address = ranges[i].last(); 764 765 assert(reserved.contains(start_address) && reserved.contains(last_address), 766 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 767 p2i(start_address), p2i(last_address)); 768 assert(start_address > prev_last_addr, 769 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 770 p2i(start_address), p2i(prev_last_addr)); 771 size_used += ranges[i].byte_size(); 772 prev_last_addr = last_address; 773 774 HeapRegion* start_region = _hrm->addr_to_region(start_address); 775 HeapRegion* last_region = _hrm->addr_to_region(last_address); 776 777 // Check for ranges that start in the same G1 region in which the previous 778 // range ended, and adjust the start address so we don't try to free 779 // the same region again. If the current range is entirely within that 780 // region, skip it. 781 if (start_region == prev_last_region) { 782 start_address = start_region->end(); 783 if (start_address > last_address) { 784 continue; 785 } 786 start_region = _hrm->addr_to_region(start_address); 787 } 788 prev_last_region = last_region; 789 790 // After verifying that each region was marked as an archive region by 791 // alloc_archive_regions, set it free and empty and uncommit it. 792 HeapRegion* curr_region = start_region; 793 while (curr_region != NULL) { 794 guarantee(curr_region->is_archive(), 795 "Expected archive region at index %u", curr_region->hrm_index()); 796 uint curr_index = curr_region->hrm_index(); 797 _archive_set.remove(curr_region); 798 curr_region->set_free(); 799 curr_region->set_top(curr_region->bottom()); 800 if (curr_region != last_region) { 801 curr_region = _hrm->next_region_in_heap(curr_region); 802 } else { 803 curr_region = NULL; 804 } 805 _hrm->shrink_at(curr_index, 1); 806 uncommitted_regions++; 807 } 808 809 // Notify mark-sweep that this is no longer an archive range. 810 G1ArchiveAllocator::clear_range_archive(ranges[i]); 811 } 812 813 if (uncommitted_regions != 0) { 814 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 815 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 816 } 817 decrease_used(size_used); 818 } 819 820 oop G1CollectedHeap::materialize_archived_object(oop obj) { 821 assert(obj != NULL, "archived obj is NULL"); 822 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 823 824 // Loading an archived object makes it strongly reachable. If it is 825 // loaded during concurrent marking, it must be enqueued to the SATB 826 // queue, shading the previously white object gray. 827 G1BarrierSet::enqueue(obj); 828 829 return obj; 830 } 831 832 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 833 ResourceMark rm; // For retrieving the thread names in log messages. 834 835 // The structure of this method has a lot of similarities to 836 // attempt_allocation_slow(). The reason these two were not merged 837 // into a single one is that such a method would require several "if 838 // allocation is not humongous do this, otherwise do that" 839 // conditional paths which would obscure its flow. In fact, an early 840 // version of this code did use a unified method which was harder to 841 // follow and, as a result, it had subtle bugs that were hard to 842 // track down. So keeping these two methods separate allows each to 843 // be more readable. It will be good to keep these two in sync as 844 // much as possible. 845 846 assert_heap_not_locked_and_not_at_safepoint(); 847 assert(is_humongous(word_size), "attempt_allocation_humongous() " 848 "should only be called for humongous allocations"); 849 850 // Humongous objects can exhaust the heap quickly, so we should check if we 851 // need to start a marking cycle at each humongous object allocation. We do 852 // the check before we do the actual allocation. The reason for doing it 853 // before the allocation is that we avoid having to keep track of the newly 854 // allocated memory while we do a GC. 855 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 856 word_size)) { 857 collect(GCCause::_g1_humongous_allocation); 858 } 859 860 // We will loop until a) we manage to successfully perform the 861 // allocation or b) we successfully schedule a collection which 862 // fails to perform the allocation. b) is the only case when we'll 863 // return NULL. 864 HeapWord* result = NULL; 865 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 866 bool should_try_gc; 867 uint gc_count_before; 868 869 870 { 871 MutexLocker x(Heap_lock); 872 873 // Given that humongous objects are not allocated in young 874 // regions, we'll first try to do the allocation without doing a 875 // collection hoping that there's enough space in the heap. 876 result = humongous_obj_allocate(word_size); 877 if (result != NULL) { 878 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 879 policy()->old_gen_alloc_tracker()-> 880 add_allocated_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 881 return result; 882 } 883 884 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 885 // the GCLocker initiated GC has been performed and then retry. This includes 886 // the case when the GC Locker is not active but has not been performed. 887 should_try_gc = !GCLocker::needs_gc(); 888 // Read the GC count while still holding the Heap_lock. 889 gc_count_before = total_collections(); 890 } 891 892 if (should_try_gc) { 893 bool succeeded; 894 result = do_collection_pause(word_size, gc_count_before, &succeeded, 895 GCCause::_g1_humongous_allocation); 896 if (result != NULL) { 897 assert(succeeded, "only way to get back a non-NULL result"); 898 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 899 Thread::current()->name(), p2i(result)); 900 return result; 901 } 902 903 if (succeeded) { 904 // We successfully scheduled a collection which failed to allocate. No 905 // point in trying to allocate further. We'll just return NULL. 906 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 907 SIZE_FORMAT " words", Thread::current()->name(), word_size); 908 return NULL; 909 } 910 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 911 Thread::current()->name(), word_size); 912 } else { 913 // Failed to schedule a collection. 914 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 915 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 916 SIZE_FORMAT " words", Thread::current()->name(), word_size); 917 return NULL; 918 } 919 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 920 // The GCLocker is either active or the GCLocker initiated 921 // GC has not yet been performed. Stall until it is and 922 // then retry the allocation. 923 GCLocker::stall_until_clear(); 924 gclocker_retry_count += 1; 925 } 926 927 928 // We can reach here if we were unsuccessful in scheduling a 929 // collection (because another thread beat us to it) or if we were 930 // stalled due to the GC locker. In either can we should retry the 931 // allocation attempt in case another thread successfully 932 // performed a collection and reclaimed enough space. 933 // Humongous object allocation always needs a lock, so we wait for the retry 934 // in the next iteration of the loop, unlike for the regular iteration case. 935 // Give a warning if we seem to be looping forever. 936 937 if ((QueuedAllocationWarningCount > 0) && 938 (try_count % QueuedAllocationWarningCount == 0)) { 939 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 940 Thread::current()->name(), try_count, word_size); 941 } 942 } 943 944 ShouldNotReachHere(); 945 return NULL; 946 } 947 948 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 949 bool expect_null_mutator_alloc_region) { 950 assert_at_safepoint_on_vm_thread(); 951 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 952 "the current alloc region was unexpectedly found to be non-NULL"); 953 954 if (!is_humongous(word_size)) { 955 return _allocator->attempt_allocation_locked(word_size); 956 } else { 957 HeapWord* result = humongous_obj_allocate(word_size); 958 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 959 collector_state()->set_initiate_conc_mark_if_possible(true); 960 } 961 return result; 962 } 963 964 ShouldNotReachHere(); 965 } 966 967 class PostCompactionPrinterClosure: public HeapRegionClosure { 968 private: 969 G1HRPrinter* _hr_printer; 970 public: 971 bool do_heap_region(HeapRegion* hr) { 972 assert(!hr->is_young(), "not expecting to find young regions"); 973 _hr_printer->post_compaction(hr); 974 return false; 975 } 976 977 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 978 : _hr_printer(hr_printer) { } 979 }; 980 981 void G1CollectedHeap::print_hrm_post_compaction() { 982 if (_hr_printer.is_active()) { 983 PostCompactionPrinterClosure cl(hr_printer()); 984 heap_region_iterate(&cl); 985 } 986 } 987 988 void G1CollectedHeap::abort_concurrent_cycle() { 989 // If we start the compaction before the CM threads finish 990 // scanning the root regions we might trip them over as we'll 991 // be moving objects / updating references. So let's wait until 992 // they are done. By telling them to abort, they should complete 993 // early. 994 _cm->root_regions()->abort(); 995 _cm->root_regions()->wait_until_scan_finished(); 996 997 // Disable discovery and empty the discovered lists 998 // for the CM ref processor. 999 _ref_processor_cm->disable_discovery(); 1000 _ref_processor_cm->abandon_partial_discovery(); 1001 _ref_processor_cm->verify_no_references_recorded(); 1002 1003 // Abandon current iterations of concurrent marking and concurrent 1004 // refinement, if any are in progress. 1005 concurrent_mark()->concurrent_cycle_abort(); 1006 } 1007 1008 void G1CollectedHeap::prepare_heap_for_full_collection() { 1009 // Make sure we'll choose a new allocation region afterwards. 1010 _allocator->release_mutator_alloc_regions(); 1011 _allocator->abandon_gc_alloc_regions(); 1012 1013 // We may have added regions to the current incremental collection 1014 // set between the last GC or pause and now. We need to clear the 1015 // incremental collection set and then start rebuilding it afresh 1016 // after this full GC. 1017 abandon_collection_set(collection_set()); 1018 1019 tear_down_region_sets(false /* free_list_only */); 1020 1021 hrm()->prepare_for_full_collection_start(); 1022 } 1023 1024 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1025 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1026 assert_used_and_recalculate_used_equal(this); 1027 _verifier->verify_region_sets_optional(); 1028 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1029 _verifier->check_bitmaps("Full GC Start"); 1030 } 1031 1032 void G1CollectedHeap::prepare_heap_for_mutators() { 1033 hrm()->prepare_for_full_collection_end(); 1034 1035 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1036 ClassLoaderDataGraph::purge(); 1037 MetaspaceUtils::verify_metrics(); 1038 1039 // Prepare heap for normal collections. 1040 assert(num_free_regions() == 0, "we should not have added any free regions"); 1041 rebuild_region_sets(false /* free_list_only */); 1042 abort_refinement(); 1043 resize_heap_if_necessary(); 1044 1045 // Rebuild the strong code root lists for each region 1046 rebuild_strong_code_roots(); 1047 1048 // Purge code root memory 1049 purge_code_root_memory(); 1050 1051 // Start a new incremental collection set for the next pause 1052 start_new_collection_set(); 1053 1054 _allocator->init_mutator_alloc_regions(); 1055 1056 // Post collection state updates. 1057 MetaspaceGC::compute_new_size(); 1058 } 1059 1060 void G1CollectedHeap::abort_refinement() { 1061 if (_hot_card_cache->use_cache()) { 1062 _hot_card_cache->reset_hot_cache(); 1063 } 1064 1065 // Discard all remembered set updates and reset refinement statistics. 1066 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1067 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1068 "DCQS should be empty"); 1069 concurrent_refine()->get_and_reset_refinement_stats(); 1070 } 1071 1072 void G1CollectedHeap::verify_after_full_collection() { 1073 _hrm->verify_optional(); 1074 _verifier->verify_region_sets_optional(); 1075 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1076 // Clear the previous marking bitmap, if needed for bitmap verification. 1077 // Note we cannot do this when we clear the next marking bitmap in 1078 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1079 // objects marked during a full GC against the previous bitmap. 1080 // But we need to clear it before calling check_bitmaps below since 1081 // the full GC has compacted objects and updated TAMS but not updated 1082 // the prev bitmap. 1083 if (G1VerifyBitmaps) { 1084 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1085 _cm->clear_prev_bitmap(workers()); 1086 } 1087 // This call implicitly verifies that the next bitmap is clear after Full GC. 1088 _verifier->check_bitmaps("Full GC End"); 1089 1090 // At this point there should be no regions in the 1091 // entire heap tagged as young. 1092 assert(check_young_list_empty(), "young list should be empty at this point"); 1093 1094 // Note: since we've just done a full GC, concurrent 1095 // marking is no longer active. Therefore we need not 1096 // re-enable reference discovery for the CM ref processor. 1097 // That will be done at the start of the next marking cycle. 1098 // We also know that the STW processor should no longer 1099 // discover any new references. 1100 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1101 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1102 _ref_processor_stw->verify_no_references_recorded(); 1103 _ref_processor_cm->verify_no_references_recorded(); 1104 } 1105 1106 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1107 // Post collection logging. 1108 // We should do this after we potentially resize the heap so 1109 // that all the COMMIT / UNCOMMIT events are generated before 1110 // the compaction events. 1111 print_hrm_post_compaction(); 1112 heap_transition->print(); 1113 print_heap_after_gc(); 1114 print_heap_regions(); 1115 } 1116 1117 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1118 bool clear_all_soft_refs) { 1119 assert_at_safepoint_on_vm_thread(); 1120 1121 if (GCLocker::check_active_before_gc()) { 1122 // Full GC was not completed. 1123 return false; 1124 } 1125 1126 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1127 soft_ref_policy()->should_clear_all_soft_refs(); 1128 1129 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1130 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1131 1132 collector.prepare_collection(); 1133 collector.collect(); 1134 collector.complete_collection(); 1135 1136 // Full collection was successfully completed. 1137 return true; 1138 } 1139 1140 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1141 // Currently, there is no facility in the do_full_collection(bool) API to notify 1142 // the caller that the collection did not succeed (e.g., because it was locked 1143 // out by the GC locker). So, right now, we'll ignore the return value. 1144 bool dummy = do_full_collection(true, /* explicit_gc */ 1145 clear_all_soft_refs); 1146 } 1147 1148 void G1CollectedHeap::resize_heap_if_necessary() { 1149 assert_at_safepoint_on_vm_thread(); 1150 1151 bool should_expand; 1152 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand); 1153 1154 if (resize_amount == 0) { 1155 return; 1156 } else if (should_expand) { 1157 expand(resize_amount, _workers); 1158 } else { 1159 shrink(resize_amount); 1160 } 1161 } 1162 1163 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1164 bool do_gc, 1165 bool clear_all_soft_refs, 1166 bool expect_null_mutator_alloc_region, 1167 bool* gc_succeeded) { 1168 *gc_succeeded = true; 1169 // Let's attempt the allocation first. 1170 HeapWord* result = 1171 attempt_allocation_at_safepoint(word_size, 1172 expect_null_mutator_alloc_region); 1173 if (result != NULL) { 1174 return result; 1175 } 1176 1177 // In a G1 heap, we're supposed to keep allocation from failing by 1178 // incremental pauses. Therefore, at least for now, we'll favor 1179 // expansion over collection. (This might change in the future if we can 1180 // do something smarter than full collection to satisfy a failed alloc.) 1181 result = expand_and_allocate(word_size); 1182 if (result != NULL) { 1183 return result; 1184 } 1185 1186 if (do_gc) { 1187 // Expansion didn't work, we'll try to do a Full GC. 1188 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1189 clear_all_soft_refs); 1190 } 1191 1192 return NULL; 1193 } 1194 1195 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1196 bool* succeeded) { 1197 assert_at_safepoint_on_vm_thread(); 1198 1199 // Attempts to allocate followed by Full GC. 1200 HeapWord* result = 1201 satisfy_failed_allocation_helper(word_size, 1202 true, /* do_gc */ 1203 false, /* clear_all_soft_refs */ 1204 false, /* expect_null_mutator_alloc_region */ 1205 succeeded); 1206 1207 if (result != NULL || !*succeeded) { 1208 return result; 1209 } 1210 1211 // Attempts to allocate followed by Full GC that will collect all soft references. 1212 result = satisfy_failed_allocation_helper(word_size, 1213 true, /* do_gc */ 1214 true, /* clear_all_soft_refs */ 1215 true, /* expect_null_mutator_alloc_region */ 1216 succeeded); 1217 1218 if (result != NULL || !*succeeded) { 1219 return result; 1220 } 1221 1222 // Attempts to allocate, no GC 1223 result = satisfy_failed_allocation_helper(word_size, 1224 false, /* do_gc */ 1225 false, /* clear_all_soft_refs */ 1226 true, /* expect_null_mutator_alloc_region */ 1227 succeeded); 1228 1229 if (result != NULL) { 1230 return result; 1231 } 1232 1233 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1234 "Flag should have been handled and cleared prior to this point"); 1235 1236 // What else? We might try synchronous finalization later. If the total 1237 // space available is large enough for the allocation, then a more 1238 // complete compaction phase than we've tried so far might be 1239 // appropriate. 1240 return NULL; 1241 } 1242 1243 // Attempting to expand the heap sufficiently 1244 // to support an allocation of the given "word_size". If 1245 // successful, perform the allocation and return the address of the 1246 // allocated block, or else "NULL". 1247 1248 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1249 assert_at_safepoint_on_vm_thread(); 1250 1251 _verifier->verify_region_sets_optional(); 1252 1253 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1254 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1255 word_size * HeapWordSize); 1256 1257 1258 if (expand(expand_bytes, _workers)) { 1259 _hrm->verify_optional(); 1260 _verifier->verify_region_sets_optional(); 1261 return attempt_allocation_at_safepoint(word_size, 1262 false /* expect_null_mutator_alloc_region */); 1263 } 1264 return NULL; 1265 } 1266 1267 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1268 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1269 aligned_expand_bytes = align_up(aligned_expand_bytes, 1270 HeapRegion::GrainBytes); 1271 1272 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1273 expand_bytes, aligned_expand_bytes); 1274 1275 if (is_maximal_no_gc()) { 1276 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1277 return false; 1278 } 1279 1280 double expand_heap_start_time_sec = os::elapsedTime(); 1281 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1282 assert(regions_to_expand > 0, "Must expand by at least one region"); 1283 1284 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1285 if (expand_time_ms != NULL) { 1286 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1287 } 1288 1289 if (expanded_by > 0) { 1290 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1291 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1292 policy()->record_new_heap_size(num_regions()); 1293 } else { 1294 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1295 1296 // The expansion of the virtual storage space was unsuccessful. 1297 // Let's see if it was because we ran out of swap. 1298 if (G1ExitOnExpansionFailure && 1299 _hrm->available() >= regions_to_expand) { 1300 // We had head room... 1301 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1302 } 1303 } 1304 return regions_to_expand > 0; 1305 } 1306 1307 bool G1CollectedHeap::expand_single_region(uint node_index) { 1308 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1309 1310 if (expanded_by == 0) { 1311 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1312 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1313 return false; 1314 } 1315 1316 policy()->record_new_heap_size(num_regions()); 1317 return true; 1318 } 1319 1320 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1321 size_t aligned_shrink_bytes = 1322 ReservedSpace::page_align_size_down(shrink_bytes); 1323 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1324 HeapRegion::GrainBytes); 1325 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1326 1327 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1328 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1329 1330 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", 1331 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1332 if (num_regions_removed > 0) { 1333 policy()->record_new_heap_size(num_regions()); 1334 } else { 1335 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1336 } 1337 } 1338 1339 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1340 _verifier->verify_region_sets_optional(); 1341 1342 // We should only reach here at the end of a Full GC or during Remark which 1343 // means we should not not be holding to any GC alloc regions. The method 1344 // below will make sure of that and do any remaining clean up. 1345 _allocator->abandon_gc_alloc_regions(); 1346 1347 // Instead of tearing down / rebuilding the free lists here, we 1348 // could instead use the remove_all_pending() method on free_list to 1349 // remove only the ones that we need to remove. 1350 tear_down_region_sets(true /* free_list_only */); 1351 shrink_helper(shrink_bytes); 1352 rebuild_region_sets(true /* free_list_only */); 1353 1354 _hrm->verify_optional(); 1355 _verifier->verify_region_sets_optional(); 1356 } 1357 1358 class OldRegionSetChecker : public HeapRegionSetChecker { 1359 public: 1360 void check_mt_safety() { 1361 // Master Old Set MT safety protocol: 1362 // (a) If we're at a safepoint, operations on the master old set 1363 // should be invoked: 1364 // - by the VM thread (which will serialize them), or 1365 // - by the GC workers while holding the FreeList_lock, if we're 1366 // at a safepoint for an evacuation pause (this lock is taken 1367 // anyway when an GC alloc region is retired so that a new one 1368 // is allocated from the free list), or 1369 // - by the GC workers while holding the OldSets_lock, if we're at a 1370 // safepoint for a cleanup pause. 1371 // (b) If we're not at a safepoint, operations on the master old set 1372 // should be invoked while holding the Heap_lock. 1373 1374 if (SafepointSynchronize::is_at_safepoint()) { 1375 guarantee(Thread::current()->is_VM_thread() || 1376 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1377 "master old set MT safety protocol at a safepoint"); 1378 } else { 1379 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1380 } 1381 } 1382 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1383 const char* get_description() { return "Old Regions"; } 1384 }; 1385 1386 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1387 public: 1388 void check_mt_safety() { 1389 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1390 "May only change archive regions during initialization or safepoint."); 1391 } 1392 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1393 const char* get_description() { return "Archive Regions"; } 1394 }; 1395 1396 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1397 public: 1398 void check_mt_safety() { 1399 // Humongous Set MT safety protocol: 1400 // (a) If we're at a safepoint, operations on the master humongous 1401 // set should be invoked by either the VM thread (which will 1402 // serialize them) or by the GC workers while holding the 1403 // OldSets_lock. 1404 // (b) If we're not at a safepoint, operations on the master 1405 // humongous set should be invoked while holding the Heap_lock. 1406 1407 if (SafepointSynchronize::is_at_safepoint()) { 1408 guarantee(Thread::current()->is_VM_thread() || 1409 OldSets_lock->owned_by_self(), 1410 "master humongous set MT safety protocol at a safepoint"); 1411 } else { 1412 guarantee(Heap_lock->owned_by_self(), 1413 "master humongous set MT safety protocol outside a safepoint"); 1414 } 1415 } 1416 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1417 const char* get_description() { return "Humongous Regions"; } 1418 }; 1419 1420 G1CollectedHeap::G1CollectedHeap() : 1421 CollectedHeap(), 1422 _young_gen_sampling_thread(NULL), 1423 _workers(NULL), 1424 _card_table(NULL), 1425 _soft_ref_policy(), 1426 _old_set("Old Region Set", new OldRegionSetChecker()), 1427 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1428 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1429 _bot(NULL), 1430 _listener(), 1431 _numa(G1NUMA::create()), 1432 _hrm(NULL), 1433 _allocator(NULL), 1434 _verifier(NULL), 1435 _summary_bytes_used(0), 1436 _bytes_used_during_gc(0), 1437 _archive_allocator(NULL), 1438 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1439 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1440 _expand_heap_after_alloc_failure(true), 1441 _g1mm(NULL), 1442 _humongous_reclaim_candidates(), 1443 _has_humongous_reclaim_candidates(false), 1444 _hr_printer(), 1445 _collector_state(), 1446 _old_marking_cycles_started(0), 1447 _old_marking_cycles_completed(0), 1448 _eden(), 1449 _survivor(), 1450 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1451 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1452 _policy(G1Policy::create_policy(_gc_timer_stw)), 1453 _heap_sizing_policy(NULL), 1454 _collection_set(this, _policy), 1455 _hot_card_cache(NULL), 1456 _rem_set(NULL), 1457 _cm(NULL), 1458 _cm_thread(NULL), 1459 _cr(NULL), 1460 _task_queues(NULL), 1461 _evacuation_failed(false), 1462 _evacuation_failed_info_array(NULL), 1463 _preserved_marks_set(true /* in_c_heap */), 1464 #ifndef PRODUCT 1465 _evacuation_failure_alot_for_current_gc(false), 1466 _evacuation_failure_alot_gc_number(0), 1467 _evacuation_failure_alot_count(0), 1468 #endif 1469 _ref_processor_stw(NULL), 1470 _is_alive_closure_stw(this), 1471 _is_subject_to_discovery_stw(this), 1472 _ref_processor_cm(NULL), 1473 _is_alive_closure_cm(this), 1474 _is_subject_to_discovery_cm(this), 1475 _region_attr() { 1476 1477 _verifier = new G1HeapVerifier(this); 1478 1479 _allocator = new G1Allocator(this); 1480 1481 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1482 1483 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1484 1485 // Override the default _filler_array_max_size so that no humongous filler 1486 // objects are created. 1487 _filler_array_max_size = _humongous_object_threshold_in_words; 1488 1489 uint n_queues = ParallelGCThreads; 1490 _task_queues = new G1ScannerTasksQueueSet(n_queues); 1491 1492 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1493 1494 for (uint i = 0; i < n_queues; i++) { 1495 G1ScannerTasksQueue* q = new G1ScannerTasksQueue(); 1496 q->initialize(); 1497 _task_queues->register_queue(i, q); 1498 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1499 } 1500 1501 // Initialize the G1EvacuationFailureALot counters and flags. 1502 NOT_PRODUCT(reset_evacuation_should_fail();) 1503 _gc_tracer_stw->initialize(); 1504 1505 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1506 } 1507 1508 static size_t actual_reserved_page_size(ReservedSpace rs) { 1509 size_t page_size = os::vm_page_size(); 1510 if (UseLargePages) { 1511 // There are two ways to manage large page memory. 1512 // 1. OS supports committing large page memory. 1513 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1514 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1515 // we reserved memory without large page. 1516 if (os::can_commit_large_page_memory() || rs.special()) { 1517 // An alignment at ReservedSpace comes from preferred page size or 1518 // heap alignment, and if the alignment came from heap alignment, it could be 1519 // larger than large pages size. So need to cap with the large page size. 1520 page_size = MIN2(rs.alignment(), os::large_page_size()); 1521 } 1522 } 1523 1524 return page_size; 1525 } 1526 1527 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1528 size_t size, 1529 size_t translation_factor) { 1530 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1531 // Allocate a new reserved space, preferring to use large pages. 1532 ReservedSpace rs(size, preferred_page_size); 1533 size_t page_size = actual_reserved_page_size(rs); 1534 G1RegionToSpaceMapper* result = 1535 G1RegionToSpaceMapper::create_mapper(rs, 1536 size, 1537 page_size, 1538 HeapRegion::GrainBytes, 1539 translation_factor, 1540 mtGC); 1541 1542 os::trace_page_sizes_for_requested_size(description, 1543 size, 1544 preferred_page_size, 1545 page_size, 1546 rs.base(), 1547 rs.size()); 1548 1549 return result; 1550 } 1551 1552 jint G1CollectedHeap::initialize_concurrent_refinement() { 1553 jint ecode = JNI_OK; 1554 _cr = G1ConcurrentRefine::create(&ecode); 1555 return ecode; 1556 } 1557 1558 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1559 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1560 if (_young_gen_sampling_thread->osthread() == NULL) { 1561 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1562 return JNI_ENOMEM; 1563 } 1564 return JNI_OK; 1565 } 1566 1567 jint G1CollectedHeap::initialize() { 1568 1569 // Necessary to satisfy locking discipline assertions. 1570 1571 MutexLocker x(Heap_lock); 1572 1573 // While there are no constraints in the GC code that HeapWordSize 1574 // be any particular value, there are multiple other areas in the 1575 // system which believe this to be true (e.g. oop->object_size in some 1576 // cases incorrectly returns the size in wordSize units rather than 1577 // HeapWordSize). 1578 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1579 1580 size_t init_byte_size = InitialHeapSize; 1581 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1582 1583 // Ensure that the sizes are properly aligned. 1584 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1585 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1586 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1587 1588 // Reserve the maximum. 1589 1590 // When compressed oops are enabled, the preferred heap base 1591 // is calculated by subtracting the requested size from the 1592 // 32Gb boundary and using the result as the base address for 1593 // heap reservation. If the requested size is not aligned to 1594 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1595 // into the ReservedHeapSpace constructor) then the actual 1596 // base of the reserved heap may end up differing from the 1597 // address that was requested (i.e. the preferred heap base). 1598 // If this happens then we could end up using a non-optimal 1599 // compressed oops mode. 1600 1601 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1602 HeapAlignment); 1603 1604 initialize_reserved_region(heap_rs); 1605 1606 // Create the barrier set for the entire reserved region. 1607 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1608 ct->initialize(); 1609 G1BarrierSet* bs = new G1BarrierSet(ct); 1610 bs->initialize(); 1611 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1612 BarrierSet::set_barrier_set(bs); 1613 _card_table = ct; 1614 1615 { 1616 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1617 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1618 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1619 } 1620 1621 // Create the hot card cache. 1622 _hot_card_cache = new G1HotCardCache(this); 1623 1624 // Carve out the G1 part of the heap. 1625 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1626 size_t page_size = actual_reserved_page_size(heap_rs); 1627 G1RegionToSpaceMapper* heap_storage = 1628 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1629 g1_rs.size(), 1630 page_size, 1631 HeapRegion::GrainBytes, 1632 1, 1633 mtJavaHeap); 1634 if(heap_storage == NULL) { 1635 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1636 return JNI_ERR; 1637 } 1638 1639 os::trace_page_sizes("Heap", 1640 MinHeapSize, 1641 reserved_byte_size, 1642 page_size, 1643 heap_rs.base(), 1644 heap_rs.size()); 1645 heap_storage->set_mapping_changed_listener(&_listener); 1646 1647 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1648 G1RegionToSpaceMapper* bot_storage = 1649 create_aux_memory_mapper("Block Offset Table", 1650 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1651 G1BlockOffsetTable::heap_map_factor()); 1652 1653 G1RegionToSpaceMapper* cardtable_storage = 1654 create_aux_memory_mapper("Card Table", 1655 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1656 G1CardTable::heap_map_factor()); 1657 1658 G1RegionToSpaceMapper* card_counts_storage = 1659 create_aux_memory_mapper("Card Counts Table", 1660 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1661 G1CardCounts::heap_map_factor()); 1662 1663 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1664 G1RegionToSpaceMapper* prev_bitmap_storage = 1665 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1666 G1RegionToSpaceMapper* next_bitmap_storage = 1667 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1668 1669 _hrm = HeapRegionManager::create_manager(this); 1670 1671 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1672 _card_table->initialize(cardtable_storage); 1673 1674 // Do later initialization work for concurrent refinement. 1675 _hot_card_cache->initialize(card_counts_storage); 1676 1677 // 6843694 - ensure that the maximum region index can fit 1678 // in the remembered set structures. 1679 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1680 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1681 1682 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1683 // start within the first card. 1684 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1685 // Also create a G1 rem set. 1686 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1687 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1688 1689 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1690 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1691 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1692 "too many cards per region"); 1693 1694 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1695 1696 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1697 1698 { 1699 HeapWord* start = _hrm->reserved().start(); 1700 HeapWord* end = _hrm->reserved().end(); 1701 size_t granularity = HeapRegion::GrainBytes; 1702 1703 _region_attr.initialize(start, end, granularity); 1704 _humongous_reclaim_candidates.initialize(start, end, granularity); 1705 } 1706 1707 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1708 true /* are_GC_task_threads */, 1709 false /* are_ConcurrentGC_threads */); 1710 if (_workers == NULL) { 1711 return JNI_ENOMEM; 1712 } 1713 _workers->initialize_workers(); 1714 1715 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1716 1717 // Create the G1ConcurrentMark data structure and thread. 1718 // (Must do this late, so that "max_regions" is defined.) 1719 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1720 _cm_thread = _cm->cm_thread(); 1721 1722 // Now expand into the initial heap size. 1723 if (!expand(init_byte_size, _workers)) { 1724 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1725 return JNI_ENOMEM; 1726 } 1727 1728 // Perform any initialization actions delegated to the policy. 1729 policy()->init(this, &_collection_set); 1730 1731 jint ecode = initialize_concurrent_refinement(); 1732 if (ecode != JNI_OK) { 1733 return ecode; 1734 } 1735 1736 ecode = initialize_young_gen_sampling_thread(); 1737 if (ecode != JNI_OK) { 1738 return ecode; 1739 } 1740 1741 { 1742 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1743 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1744 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1745 } 1746 1747 // Here we allocate the dummy HeapRegion that is required by the 1748 // G1AllocRegion class. 1749 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1750 1751 // We'll re-use the same region whether the alloc region will 1752 // require BOT updates or not and, if it doesn't, then a non-young 1753 // region will complain that it cannot support allocations without 1754 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1755 dummy_region->set_eden(); 1756 // Make sure it's full. 1757 dummy_region->set_top(dummy_region->end()); 1758 G1AllocRegion::setup(this, dummy_region); 1759 1760 _allocator->init_mutator_alloc_regions(); 1761 1762 // Do create of the monitoring and management support so that 1763 // values in the heap have been properly initialized. 1764 _g1mm = new G1MonitoringSupport(this); 1765 1766 G1StringDedup::initialize(); 1767 1768 _preserved_marks_set.init(ParallelGCThreads); 1769 1770 _collection_set.initialize(max_regions()); 1771 1772 G1InitLogger::print(); 1773 1774 return JNI_OK; 1775 } 1776 1777 void G1CollectedHeap::stop() { 1778 // Stop all concurrent threads. We do this to make sure these threads 1779 // do not continue to execute and access resources (e.g. logging) 1780 // that are destroyed during shutdown. 1781 _cr->stop(); 1782 _young_gen_sampling_thread->stop(); 1783 _cm_thread->stop(); 1784 if (G1StringDedup::is_enabled()) { 1785 G1StringDedup::stop(); 1786 } 1787 } 1788 1789 void G1CollectedHeap::safepoint_synchronize_begin() { 1790 SuspendibleThreadSet::synchronize(); 1791 } 1792 1793 void G1CollectedHeap::safepoint_synchronize_end() { 1794 SuspendibleThreadSet::desynchronize(); 1795 } 1796 1797 void G1CollectedHeap::post_initialize() { 1798 CollectedHeap::post_initialize(); 1799 ref_processing_init(); 1800 } 1801 1802 void G1CollectedHeap::ref_processing_init() { 1803 // Reference processing in G1 currently works as follows: 1804 // 1805 // * There are two reference processor instances. One is 1806 // used to record and process discovered references 1807 // during concurrent marking; the other is used to 1808 // record and process references during STW pauses 1809 // (both full and incremental). 1810 // * Both ref processors need to 'span' the entire heap as 1811 // the regions in the collection set may be dotted around. 1812 // 1813 // * For the concurrent marking ref processor: 1814 // * Reference discovery is enabled at concurrent start. 1815 // * Reference discovery is disabled and the discovered 1816 // references processed etc during remarking. 1817 // * Reference discovery is MT (see below). 1818 // * Reference discovery requires a barrier (see below). 1819 // * Reference processing may or may not be MT 1820 // (depending on the value of ParallelRefProcEnabled 1821 // and ParallelGCThreads). 1822 // * A full GC disables reference discovery by the CM 1823 // ref processor and abandons any entries on it's 1824 // discovered lists. 1825 // 1826 // * For the STW processor: 1827 // * Non MT discovery is enabled at the start of a full GC. 1828 // * Processing and enqueueing during a full GC is non-MT. 1829 // * During a full GC, references are processed after marking. 1830 // 1831 // * Discovery (may or may not be MT) is enabled at the start 1832 // of an incremental evacuation pause. 1833 // * References are processed near the end of a STW evacuation pause. 1834 // * For both types of GC: 1835 // * Discovery is atomic - i.e. not concurrent. 1836 // * Reference discovery will not need a barrier. 1837 1838 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1839 1840 // Concurrent Mark ref processor 1841 _ref_processor_cm = 1842 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1843 mt_processing, // mt processing 1844 ParallelGCThreads, // degree of mt processing 1845 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1846 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1847 false, // Reference discovery is not atomic 1848 &_is_alive_closure_cm, // is alive closure 1849 true); // allow changes to number of processing threads 1850 1851 // STW ref processor 1852 _ref_processor_stw = 1853 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1854 mt_processing, // mt processing 1855 ParallelGCThreads, // degree of mt processing 1856 (ParallelGCThreads > 1), // mt discovery 1857 ParallelGCThreads, // degree of mt discovery 1858 true, // Reference discovery is atomic 1859 &_is_alive_closure_stw, // is alive closure 1860 true); // allow changes to number of processing threads 1861 } 1862 1863 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1864 return &_soft_ref_policy; 1865 } 1866 1867 size_t G1CollectedHeap::capacity() const { 1868 return _hrm->length() * HeapRegion::GrainBytes; 1869 } 1870 1871 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1872 return _hrm->total_free_bytes(); 1873 } 1874 1875 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1876 _hot_card_cache->drain(cl, worker_id); 1877 } 1878 1879 // Computes the sum of the storage used by the various regions. 1880 size_t G1CollectedHeap::used() const { 1881 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1882 if (_archive_allocator != NULL) { 1883 result += _archive_allocator->used(); 1884 } 1885 return result; 1886 } 1887 1888 size_t G1CollectedHeap::used_unlocked() const { 1889 return _summary_bytes_used; 1890 } 1891 1892 class SumUsedClosure: public HeapRegionClosure { 1893 size_t _used; 1894 public: 1895 SumUsedClosure() : _used(0) {} 1896 bool do_heap_region(HeapRegion* r) { 1897 _used += r->used(); 1898 return false; 1899 } 1900 size_t result() { return _used; } 1901 }; 1902 1903 size_t G1CollectedHeap::recalculate_used() const { 1904 SumUsedClosure blk; 1905 heap_region_iterate(&blk); 1906 return blk.result(); 1907 } 1908 1909 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1910 switch (cause) { 1911 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1912 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1913 case GCCause::_wb_conc_mark: return true; 1914 default : return false; 1915 } 1916 } 1917 1918 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1919 switch (cause) { 1920 case GCCause::_g1_humongous_allocation: return true; 1921 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1922 case GCCause::_wb_breakpoint: return true; 1923 default: return is_user_requested_concurrent_full_gc(cause); 1924 } 1925 } 1926 1927 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 1928 if (policy()->force_upgrade_to_full()) { 1929 return true; 1930 } else if (should_do_concurrent_full_gc(_gc_cause)) { 1931 return false; 1932 } else if (has_regions_left_for_allocation()) { 1933 return false; 1934 } else { 1935 return true; 1936 } 1937 } 1938 1939 #ifndef PRODUCT 1940 void G1CollectedHeap::allocate_dummy_regions() { 1941 // Let's fill up most of the region 1942 size_t word_size = HeapRegion::GrainWords - 1024; 1943 // And as a result the region we'll allocate will be humongous. 1944 guarantee(is_humongous(word_size), "sanity"); 1945 1946 // _filler_array_max_size is set to humongous object threshold 1947 // but temporarily change it to use CollectedHeap::fill_with_object(). 1948 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size); 1949 1950 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1951 // Let's use the existing mechanism for the allocation 1952 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 1953 if (dummy_obj != NULL) { 1954 MemRegion mr(dummy_obj, word_size); 1955 CollectedHeap::fill_with_object(mr); 1956 } else { 1957 // If we can't allocate once, we probably cannot allocate 1958 // again. Let's get out of the loop. 1959 break; 1960 } 1961 } 1962 } 1963 #endif // !PRODUCT 1964 1965 void G1CollectedHeap::increment_old_marking_cycles_started() { 1966 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 1967 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 1968 "Wrong marking cycle count (started: %d, completed: %d)", 1969 _old_marking_cycles_started, _old_marking_cycles_completed); 1970 1971 _old_marking_cycles_started++; 1972 } 1973 1974 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 1975 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 1976 1977 // We assume that if concurrent == true, then the caller is a 1978 // concurrent thread that was joined the Suspendible Thread 1979 // Set. If there's ever a cheap way to check this, we should add an 1980 // assert here. 1981 1982 // Given that this method is called at the end of a Full GC or of a 1983 // concurrent cycle, and those can be nested (i.e., a Full GC can 1984 // interrupt a concurrent cycle), the number of full collections 1985 // completed should be either one (in the case where there was no 1986 // nesting) or two (when a Full GC interrupted a concurrent cycle) 1987 // behind the number of full collections started. 1988 1989 // This is the case for the inner caller, i.e. a Full GC. 1990 assert(concurrent || 1991 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 1992 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 1993 "for inner caller (Full GC): _old_marking_cycles_started = %u " 1994 "is inconsistent with _old_marking_cycles_completed = %u", 1995 _old_marking_cycles_started, _old_marking_cycles_completed); 1996 1997 // This is the case for the outer caller, i.e. the concurrent cycle. 1998 assert(!concurrent || 1999 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2000 "for outer caller (concurrent cycle): " 2001 "_old_marking_cycles_started = %u " 2002 "is inconsistent with _old_marking_cycles_completed = %u", 2003 _old_marking_cycles_started, _old_marking_cycles_completed); 2004 2005 _old_marking_cycles_completed += 1; 2006 2007 // We need to clear the "in_progress" flag in the CM thread before 2008 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2009 // is set) so that if a waiter requests another System.gc() it doesn't 2010 // incorrectly see that a marking cycle is still in progress. 2011 if (concurrent) { 2012 _cm_thread->set_idle(); 2013 } 2014 2015 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 2016 // for a full GC to finish that their wait is over. 2017 ml.notify_all(); 2018 } 2019 2020 void G1CollectedHeap::collect(GCCause::Cause cause) { 2021 try_collect(cause); 2022 } 2023 2024 // Return true if (x < y) with allowance for wraparound. 2025 static bool gc_counter_less_than(uint x, uint y) { 2026 return (x - y) > (UINT_MAX/2); 2027 } 2028 2029 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 2030 // Macro so msg printing is format-checked. 2031 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 2032 do { \ 2033 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 2034 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 2035 ResourceMark rm; /* For thread name. */ \ 2036 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 2037 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 2038 Thread::current()->name(), \ 2039 GCCause::to_string(cause)); \ 2040 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 2041 } \ 2042 } while (0) 2043 2044 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 2045 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 2046 2047 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 2048 uint gc_counter, 2049 uint old_marking_started_before) { 2050 assert_heap_not_locked(); 2051 assert(should_do_concurrent_full_gc(cause), 2052 "Non-concurrent cause %s", GCCause::to_string(cause)); 2053 2054 for (uint i = 1; true; ++i) { 2055 // Try to schedule concurrent start evacuation pause that will 2056 // start a concurrent cycle. 2057 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 2058 VM_G1TryInitiateConcMark op(gc_counter, 2059 cause, 2060 policy()->max_pause_time_ms()); 2061 VMThread::execute(&op); 2062 2063 // Request is trivially finished. 2064 if (cause == GCCause::_g1_periodic_collection) { 2065 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 2066 return op.gc_succeeded(); 2067 } 2068 2069 // If VMOp skipped initiating concurrent marking cycle because 2070 // we're terminating, then we're done. 2071 if (op.terminating()) { 2072 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 2073 return false; 2074 } 2075 2076 // Lock to get consistent set of values. 2077 uint old_marking_started_after; 2078 uint old_marking_completed_after; 2079 { 2080 MutexLocker ml(Heap_lock); 2081 // Update gc_counter for retrying VMOp if needed. Captured here to be 2082 // consistent with the values we use below for termination tests. If 2083 // a retry is needed after a possible wait, and another collection 2084 // occurs in the meantime, it will cause our retry to be skipped and 2085 // we'll recheck for termination with updated conditions from that 2086 // more recent collection. That's what we want, rather than having 2087 // our retry possibly perform an unnecessary collection. 2088 gc_counter = total_collections(); 2089 old_marking_started_after = _old_marking_cycles_started; 2090 old_marking_completed_after = _old_marking_cycles_completed; 2091 } 2092 2093 if (cause == GCCause::_wb_breakpoint) { 2094 if (op.gc_succeeded()) { 2095 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2096 return true; 2097 } 2098 // When _wb_breakpoint there can't be another cycle or deferred. 2099 assert(!op.cycle_already_in_progress(), "invariant"); 2100 assert(!op.whitebox_attached(), "invariant"); 2101 // Concurrent cycle attempt might have been cancelled by some other 2102 // collection, so retry. Unlike other cases below, we want to retry 2103 // even if cancelled by a STW full collection, because we really want 2104 // to start a concurrent cycle. 2105 if (old_marking_started_before != old_marking_started_after) { 2106 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 2107 old_marking_started_before = old_marking_started_after; 2108 } 2109 } else if (!GCCause::is_user_requested_gc(cause)) { 2110 // For an "automatic" (not user-requested) collection, we just need to 2111 // ensure that progress is made. 2112 // 2113 // Request is finished if any of 2114 // (1) the VMOp successfully performed a GC, 2115 // (2) a concurrent cycle was already in progress, 2116 // (3) whitebox is controlling concurrent cycles, 2117 // (4) a new cycle was started (by this thread or some other), or 2118 // (5) a Full GC was performed. 2119 // Cases (4) and (5) are detected together by a change to 2120 // _old_marking_cycles_started. 2121 // 2122 // Note that (1) does not imply (4). If we're still in the mixed 2123 // phase of an earlier concurrent collection, the request to make the 2124 // collection a concurrent start won't be honored. If we don't check for 2125 // both conditions we'll spin doing back-to-back collections. 2126 if (op.gc_succeeded() || 2127 op.cycle_already_in_progress() || 2128 op.whitebox_attached() || 2129 (old_marking_started_before != old_marking_started_after)) { 2130 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2131 return true; 2132 } 2133 } else { // User-requested GC. 2134 // For a user-requested collection, we want to ensure that a complete 2135 // full collection has been performed before returning, but without 2136 // waiting for more than needed. 2137 2138 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 2139 // new cycle was started. That's good, because it's not clear what we 2140 // should do otherwise. Trying again just does back to back GCs. 2141 // Can't wait for someone else to start a cycle. And returning fails 2142 // to meet the goal of ensuring a full collection was performed. 2143 assert(!op.gc_succeeded() || 2144 (old_marking_started_before != old_marking_started_after), 2145 "invariant: succeeded %s, started before %u, started after %u", 2146 BOOL_TO_STR(op.gc_succeeded()), 2147 old_marking_started_before, old_marking_started_after); 2148 2149 // Request is finished if a full collection (concurrent or stw) 2150 // was started after this request and has completed, e.g. 2151 // started_before < completed_after. 2152 if (gc_counter_less_than(old_marking_started_before, 2153 old_marking_completed_after)) { 2154 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2155 return true; 2156 } 2157 2158 if (old_marking_started_after != old_marking_completed_after) { 2159 // If there is an in-progress cycle (possibly started by us), then 2160 // wait for that cycle to complete, e.g. 2161 // while completed_now < started_after. 2162 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2163 MonitorLocker ml(G1OldGCCount_lock); 2164 while (gc_counter_less_than(_old_marking_cycles_completed, 2165 old_marking_started_after)) { 2166 ml.wait(); 2167 } 2168 // Request is finished if the collection we just waited for was 2169 // started after this request. 2170 if (old_marking_started_before != old_marking_started_after) { 2171 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2172 return true; 2173 } 2174 } 2175 2176 // If VMOp was successful then it started a new cycle that the above 2177 // wait &etc should have recognized as finishing this request. This 2178 // differs from a non-user-request, where gc_succeeded does not imply 2179 // a new cycle was started. 2180 assert(!op.gc_succeeded(), "invariant"); 2181 2182 if (op.cycle_already_in_progress()) { 2183 // If VMOp failed because a cycle was already in progress, it 2184 // is now complete. But it didn't finish this user-requested 2185 // GC, so try again. 2186 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2187 continue; 2188 } else if (op.whitebox_attached()) { 2189 // If WhiteBox wants control, wait for notification of a state 2190 // change in the controller, then try again. Don't wait for 2191 // release of control, since collections may complete while in 2192 // control. Note: This won't recognize a STW full collection 2193 // while waiting; we can't wait on multiple monitors. 2194 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 2195 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 2196 if (ConcurrentGCBreakpoints::is_controlled()) { 2197 ml.wait(); 2198 } 2199 continue; 2200 } 2201 } 2202 2203 // Collection failed and should be retried. 2204 assert(op.transient_failure(), "invariant"); 2205 2206 if (GCLocker::is_active_and_needs_gc()) { 2207 // If GCLocker is active, wait until clear before retrying. 2208 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2209 GCLocker::stall_until_clear(); 2210 } 2211 2212 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2213 } 2214 } 2215 2216 bool G1CollectedHeap::try_collect(GCCause::Cause cause) { 2217 assert_heap_not_locked(); 2218 2219 // Lock to get consistent set of values. 2220 uint gc_count_before; 2221 uint full_gc_count_before; 2222 uint old_marking_started_before; 2223 { 2224 MutexLocker ml(Heap_lock); 2225 gc_count_before = total_collections(); 2226 full_gc_count_before = total_full_collections(); 2227 old_marking_started_before = _old_marking_cycles_started; 2228 } 2229 2230 if (should_do_concurrent_full_gc(cause)) { 2231 return try_collect_concurrently(cause, 2232 gc_count_before, 2233 old_marking_started_before); 2234 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2235 // Indicate failure to be consistent with VMOp failure due to 2236 // another collection slipping in after our gc_count but before 2237 // our request is processed. 2238 return false; 2239 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2240 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2241 2242 // Schedule a standard evacuation pause. We're setting word_size 2243 // to 0 which means that we are not requesting a post-GC allocation. 2244 VM_G1CollectForAllocation op(0, /* word_size */ 2245 gc_count_before, 2246 cause, 2247 policy()->max_pause_time_ms()); 2248 VMThread::execute(&op); 2249 return op.gc_succeeded(); 2250 } else { 2251 // Schedule a Full GC. 2252 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2253 VMThread::execute(&op); 2254 return op.gc_succeeded(); 2255 } 2256 } 2257 2258 bool G1CollectedHeap::is_in(const void* p) const { 2259 if (_hrm->reserved().contains(p)) { 2260 // Given that we know that p is in the reserved space, 2261 // heap_region_containing() should successfully 2262 // return the containing region. 2263 HeapRegion* hr = heap_region_containing(p); 2264 return hr->is_in(p); 2265 } else { 2266 return false; 2267 } 2268 } 2269 2270 #ifdef ASSERT 2271 bool G1CollectedHeap::is_in_exact(const void* p) const { 2272 bool contains = reserved_region().contains(p); 2273 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2274 if (contains && available) { 2275 return true; 2276 } else { 2277 return false; 2278 } 2279 } 2280 #endif 2281 2282 // Iteration functions. 2283 2284 // Iterates an ObjectClosure over all objects within a HeapRegion. 2285 2286 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2287 ObjectClosure* _cl; 2288 public: 2289 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2290 bool do_heap_region(HeapRegion* r) { 2291 if (!r->is_continues_humongous()) { 2292 r->object_iterate(_cl); 2293 } 2294 return false; 2295 } 2296 }; 2297 2298 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2299 IterateObjectClosureRegionClosure blk(cl); 2300 heap_region_iterate(&blk); 2301 } 2302 2303 void G1CollectedHeap::keep_alive(oop obj) { 2304 G1BarrierSet::enqueue(obj); 2305 } 2306 2307 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2308 _hrm->iterate(cl); 2309 } 2310 2311 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2312 HeapRegionClaimer *hrclaimer, 2313 uint worker_id) const { 2314 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2315 } 2316 2317 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2318 HeapRegionClaimer *hrclaimer) const { 2319 _hrm->par_iterate(cl, hrclaimer, 0); 2320 } 2321 2322 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2323 _collection_set.iterate(cl); 2324 } 2325 2326 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2327 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers()); 2328 } 2329 2330 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2331 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2332 } 2333 2334 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2335 HeapRegion* hr = heap_region_containing(addr); 2336 return hr->block_start(addr); 2337 } 2338 2339 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2340 HeapRegion* hr = heap_region_containing(addr); 2341 return hr->block_is_obj(addr); 2342 } 2343 2344 bool G1CollectedHeap::supports_tlab_allocation() const { 2345 return true; 2346 } 2347 2348 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2349 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2350 } 2351 2352 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2353 return _eden.length() * HeapRegion::GrainBytes; 2354 } 2355 2356 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2357 // must be equal to the humongous object limit. 2358 size_t G1CollectedHeap::max_tlab_size() const { 2359 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2360 } 2361 2362 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2363 return _allocator->unsafe_max_tlab_alloc(); 2364 } 2365 2366 size_t G1CollectedHeap::max_capacity() const { 2367 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2368 } 2369 2370 size_t G1CollectedHeap::max_reserved_capacity() const { 2371 return _hrm->max_length() * HeapRegion::GrainBytes; 2372 } 2373 2374 jlong G1CollectedHeap::millis_since_last_gc() { 2375 // See the notes in GenCollectedHeap::millis_since_last_gc() 2376 // for more information about the implementation. 2377 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2378 _policy->collection_pause_end_millis(); 2379 if (ret_val < 0) { 2380 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2381 ". returning zero instead.", ret_val); 2382 return 0; 2383 } 2384 return ret_val; 2385 } 2386 2387 void G1CollectedHeap::deduplicate_string(oop str) { 2388 assert(java_lang_String::is_instance(str), "invariant"); 2389 2390 if (G1StringDedup::is_enabled()) { 2391 G1StringDedup::deduplicate(str); 2392 } 2393 } 2394 2395 void G1CollectedHeap::prepare_for_verify() { 2396 _verifier->prepare_for_verify(); 2397 } 2398 2399 void G1CollectedHeap::verify(VerifyOption vo) { 2400 _verifier->verify(vo); 2401 } 2402 2403 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2404 return true; 2405 } 2406 2407 bool G1CollectedHeap::is_heterogeneous_heap() const { 2408 return G1Arguments::is_heterogeneous_heap(); 2409 } 2410 2411 class PrintRegionClosure: public HeapRegionClosure { 2412 outputStream* _st; 2413 public: 2414 PrintRegionClosure(outputStream* st) : _st(st) {} 2415 bool do_heap_region(HeapRegion* r) { 2416 r->print_on(_st); 2417 return false; 2418 } 2419 }; 2420 2421 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2422 const HeapRegion* hr, 2423 const VerifyOption vo) const { 2424 switch (vo) { 2425 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2426 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2427 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2428 default: ShouldNotReachHere(); 2429 } 2430 return false; // keep some compilers happy 2431 } 2432 2433 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2434 const VerifyOption vo) const { 2435 switch (vo) { 2436 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2437 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2438 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2439 default: ShouldNotReachHere(); 2440 } 2441 return false; // keep some compilers happy 2442 } 2443 2444 void G1CollectedHeap::print_heap_regions() const { 2445 LogTarget(Trace, gc, heap, region) lt; 2446 if (lt.is_enabled()) { 2447 LogStream ls(lt); 2448 print_regions_on(&ls); 2449 } 2450 } 2451 2452 void G1CollectedHeap::print_on(outputStream* st) const { 2453 st->print(" %-20s", "garbage-first heap"); 2454 if (_hrm != NULL) { 2455 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2456 capacity()/K, used_unlocked()/K); 2457 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2458 p2i(_hrm->reserved().start()), 2459 p2i(_hrm->reserved().end())); 2460 } 2461 st->cr(); 2462 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2463 uint young_regions = young_regions_count(); 2464 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2465 (size_t) young_regions * HeapRegion::GrainBytes / K); 2466 uint survivor_regions = survivor_regions_count(); 2467 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2468 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2469 st->cr(); 2470 if (_numa->is_enabled()) { 2471 uint num_nodes = _numa->num_active_nodes(); 2472 st->print(" remaining free region(s) on each NUMA node: "); 2473 const int* node_ids = _numa->node_ids(); 2474 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2475 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0); 2476 st->print("%d=%u ", node_ids[node_index], num_free_regions); 2477 } 2478 st->cr(); 2479 } 2480 MetaspaceUtils::print_on(st); 2481 } 2482 2483 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2484 if (_hrm == NULL) { 2485 return; 2486 } 2487 2488 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2489 "HS=humongous(starts), HC=humongous(continues), " 2490 "CS=collection set, F=free, " 2491 "OA=open archive, CA=closed archive, " 2492 "TAMS=top-at-mark-start (previous, next)"); 2493 PrintRegionClosure blk(st); 2494 heap_region_iterate(&blk); 2495 } 2496 2497 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2498 print_on(st); 2499 2500 // Print the per-region information. 2501 if (_hrm != NULL) { 2502 st->cr(); 2503 print_regions_on(st); 2504 } 2505 } 2506 2507 void G1CollectedHeap::print_on_error(outputStream* st) const { 2508 this->CollectedHeap::print_on_error(st); 2509 2510 if (_cm != NULL) { 2511 st->cr(); 2512 _cm->print_on_error(st); 2513 } 2514 } 2515 2516 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2517 workers()->threads_do(tc); 2518 tc->do_thread(_cm_thread); 2519 _cm->threads_do(tc); 2520 _cr->threads_do(tc); 2521 tc->do_thread(_young_gen_sampling_thread); 2522 if (G1StringDedup::is_enabled()) { 2523 G1StringDedup::threads_do(tc); 2524 } 2525 } 2526 2527 void G1CollectedHeap::print_tracing_info() const { 2528 rem_set()->print_summary_info(); 2529 concurrent_mark()->print_summary_info(); 2530 } 2531 2532 #ifndef PRODUCT 2533 // Helpful for debugging RSet issues. 2534 2535 class PrintRSetsClosure : public HeapRegionClosure { 2536 private: 2537 const char* _msg; 2538 size_t _occupied_sum; 2539 2540 public: 2541 bool do_heap_region(HeapRegion* r) { 2542 HeapRegionRemSet* hrrs = r->rem_set(); 2543 size_t occupied = hrrs->occupied(); 2544 _occupied_sum += occupied; 2545 2546 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2547 if (occupied == 0) { 2548 tty->print_cr(" RSet is empty"); 2549 } else { 2550 hrrs->print(); 2551 } 2552 tty->print_cr("----------"); 2553 return false; 2554 } 2555 2556 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2557 tty->cr(); 2558 tty->print_cr("========================================"); 2559 tty->print_cr("%s", msg); 2560 tty->cr(); 2561 } 2562 2563 ~PrintRSetsClosure() { 2564 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2565 tty->print_cr("========================================"); 2566 tty->cr(); 2567 } 2568 }; 2569 2570 void G1CollectedHeap::print_cset_rsets() { 2571 PrintRSetsClosure cl("Printing CSet RSets"); 2572 collection_set_iterate_all(&cl); 2573 } 2574 2575 void G1CollectedHeap::print_all_rsets() { 2576 PrintRSetsClosure cl("Printing All RSets");; 2577 heap_region_iterate(&cl); 2578 } 2579 #endif // PRODUCT 2580 2581 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2582 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2583 } 2584 2585 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2586 2587 size_t eden_used_bytes = _eden.used_bytes(); 2588 size_t survivor_used_bytes = _survivor.used_bytes(); 2589 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2590 2591 size_t eden_capacity_bytes = 2592 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2593 2594 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2595 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2596 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2597 } 2598 2599 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2600 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2601 stats->unused(), stats->used(), stats->region_end_waste(), 2602 stats->regions_filled(), stats->direct_allocated(), 2603 stats->failure_used(), stats->failure_waste()); 2604 } 2605 2606 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2607 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2608 gc_tracer->report_gc_heap_summary(when, heap_summary); 2609 2610 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2611 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2612 } 2613 2614 void G1CollectedHeap::gc_prologue(bool full) { 2615 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2616 2617 // This summary needs to be printed before incrementing total collections. 2618 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2619 2620 // Update common counters. 2621 increment_total_collections(full /* full gc */); 2622 if (full || collector_state()->in_concurrent_start_gc()) { 2623 increment_old_marking_cycles_started(); 2624 } 2625 2626 // Fill TLAB's and such 2627 { 2628 Ticks start = Ticks::now(); 2629 ensure_parsability(true); 2630 Tickspan dt = Ticks::now() - start; 2631 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS); 2632 } 2633 2634 if (!full) { 2635 // Flush dirty card queues to qset, so later phases don't need to account 2636 // for partially filled per-thread queues and such. Not needed for full 2637 // collections, which ignore those logs. 2638 Ticks start = Ticks::now(); 2639 G1BarrierSet::dirty_card_queue_set().concatenate_logs(); 2640 Tickspan dt = Ticks::now() - start; 2641 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS); 2642 } 2643 } 2644 2645 void G1CollectedHeap::gc_epilogue(bool full) { 2646 // Update common counters. 2647 if (full) { 2648 // Update the number of full collections that have been completed. 2649 increment_old_marking_cycles_completed(false /* concurrent */); 2650 } 2651 2652 // We are at the end of the GC. Total collections has already been increased. 2653 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2654 2655 // FIXME: what is this about? 2656 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2657 // is set. 2658 #if COMPILER2_OR_JVMCI 2659 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2660 #endif 2661 2662 double start = os::elapsedTime(); 2663 resize_all_tlabs(); 2664 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2665 2666 MemoryService::track_memory_usage(); 2667 // We have just completed a GC. Update the soft reference 2668 // policy with the new heap occupancy 2669 Universe::update_heap_info_at_gc(); 2670 2671 // Print NUMA statistics. 2672 _numa->print_statistics(); 2673 } 2674 2675 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2676 LogTarget(Trace, gc, heap, verify) lt; 2677 2678 if (lt.is_enabled()) { 2679 LogStream ls(lt); 2680 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2681 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2682 heap_region_iterate(&cl); 2683 } 2684 } 2685 2686 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2687 uint gc_count_before, 2688 bool* succeeded, 2689 GCCause::Cause gc_cause) { 2690 assert_heap_not_locked_and_not_at_safepoint(); 2691 VM_G1CollectForAllocation op(word_size, 2692 gc_count_before, 2693 gc_cause, 2694 policy()->max_pause_time_ms()); 2695 VMThread::execute(&op); 2696 2697 HeapWord* result = op.result(); 2698 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2699 assert(result == NULL || ret_succeeded, 2700 "the result should be NULL if the VM did not succeed"); 2701 *succeeded = ret_succeeded; 2702 2703 assert_heap_not_locked(); 2704 return result; 2705 } 2706 2707 void G1CollectedHeap::do_concurrent_mark() { 2708 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2709 if (!_cm_thread->in_progress()) { 2710 _cm_thread->set_started(); 2711 CGC_lock->notify(); 2712 } 2713 } 2714 2715 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2716 // We don't nominate objects with many remembered set entries, on 2717 // the assumption that such objects are likely still live. 2718 HeapRegionRemSet* rem_set = r->rem_set(); 2719 2720 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2721 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2722 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2723 } 2724 2725 #ifndef PRODUCT 2726 void G1CollectedHeap::verify_region_attr_remset_update() { 2727 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2728 public: 2729 virtual bool do_heap_region(HeapRegion* r) { 2730 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2731 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2732 assert(r->rem_set()->is_tracked() == needs_remset_update, 2733 "Region %u remset tracking status (%s) different to region attribute (%s)", 2734 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2735 return false; 2736 } 2737 } cl; 2738 heap_region_iterate(&cl); 2739 } 2740 #endif 2741 2742 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2743 public: 2744 bool do_heap_region(HeapRegion* hr) { 2745 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2746 hr->verify_rem_set(); 2747 } 2748 return false; 2749 } 2750 }; 2751 2752 uint G1CollectedHeap::num_task_queues() const { 2753 return _task_queues->size(); 2754 } 2755 2756 #if TASKQUEUE_STATS 2757 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2758 st->print_raw_cr("GC Task Stats"); 2759 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2760 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2761 } 2762 2763 void G1CollectedHeap::print_taskqueue_stats() const { 2764 if (!log_is_enabled(Trace, gc, task, stats)) { 2765 return; 2766 } 2767 Log(gc, task, stats) log; 2768 ResourceMark rm; 2769 LogStream ls(log.trace()); 2770 outputStream* st = &ls; 2771 2772 print_taskqueue_stats_hdr(st); 2773 2774 TaskQueueStats totals; 2775 const uint n = num_task_queues(); 2776 for (uint i = 0; i < n; ++i) { 2777 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2778 totals += task_queue(i)->stats; 2779 } 2780 st->print_raw("tot "); totals.print(st); st->cr(); 2781 2782 DEBUG_ONLY(totals.verify()); 2783 } 2784 2785 void G1CollectedHeap::reset_taskqueue_stats() { 2786 const uint n = num_task_queues(); 2787 for (uint i = 0; i < n; ++i) { 2788 task_queue(i)->stats.reset(); 2789 } 2790 } 2791 #endif // TASKQUEUE_STATS 2792 2793 void G1CollectedHeap::wait_for_root_region_scanning() { 2794 double scan_wait_start = os::elapsedTime(); 2795 // We have to wait until the CM threads finish scanning the 2796 // root regions as it's the only way to ensure that all the 2797 // objects on them have been correctly scanned before we start 2798 // moving them during the GC. 2799 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2800 double wait_time_ms = 0.0; 2801 if (waited) { 2802 double scan_wait_end = os::elapsedTime(); 2803 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2804 } 2805 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2806 } 2807 2808 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2809 private: 2810 G1HRPrinter* _hr_printer; 2811 public: 2812 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2813 2814 virtual bool do_heap_region(HeapRegion* r) { 2815 _hr_printer->cset(r); 2816 return false; 2817 } 2818 }; 2819 2820 void G1CollectedHeap::start_new_collection_set() { 2821 double start = os::elapsedTime(); 2822 2823 collection_set()->start_incremental_building(); 2824 2825 clear_region_attr(); 2826 2827 guarantee(_eden.length() == 0, "eden should have been cleared"); 2828 policy()->transfer_survivors_to_cset(survivor()); 2829 2830 // We redo the verification but now wrt to the new CSet which 2831 // has just got initialized after the previous CSet was freed. 2832 _cm->verify_no_collection_set_oops(); 2833 2834 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2835 } 2836 2837 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2838 2839 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2840 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2841 collection_set()->optional_region_length()); 2842 2843 _cm->verify_no_collection_set_oops(); 2844 2845 if (_hr_printer.is_active()) { 2846 G1PrintCollectionSetClosure cl(&_hr_printer); 2847 _collection_set.iterate(&cl); 2848 _collection_set.iterate_optional(&cl); 2849 } 2850 } 2851 2852 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2853 if (collector_state()->in_concurrent_start_gc()) { 2854 return G1HeapVerifier::G1VerifyConcurrentStart; 2855 } else if (collector_state()->in_young_only_phase()) { 2856 return G1HeapVerifier::G1VerifyYoungNormal; 2857 } else { 2858 return G1HeapVerifier::G1VerifyMixed; 2859 } 2860 } 2861 2862 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2863 if (VerifyRememberedSets) { 2864 log_info(gc, verify)("[Verifying RemSets before GC]"); 2865 VerifyRegionRemSetClosure v_cl; 2866 heap_region_iterate(&v_cl); 2867 } 2868 _verifier->verify_before_gc(type); 2869 _verifier->check_bitmaps("GC Start"); 2870 verify_numa_regions("GC Start"); 2871 } 2872 2873 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2874 if (VerifyRememberedSets) { 2875 log_info(gc, verify)("[Verifying RemSets after GC]"); 2876 VerifyRegionRemSetClosure v_cl; 2877 heap_region_iterate(&v_cl); 2878 } 2879 _verifier->verify_after_gc(type); 2880 _verifier->check_bitmaps("GC End"); 2881 verify_numa_regions("GC End"); 2882 } 2883 2884 void G1CollectedHeap::expand_heap_after_young_collection(){ 2885 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount(); 2886 if (expand_bytes > 0) { 2887 // No need for an ergo logging here, 2888 // expansion_amount() does this when it returns a value > 0. 2889 double expand_ms; 2890 if (!expand(expand_bytes, _workers, &expand_ms)) { 2891 // We failed to expand the heap. Cannot do anything about it. 2892 } 2893 phase_times()->record_expand_heap_time(expand_ms); 2894 } 2895 } 2896 2897 const char* G1CollectedHeap::young_gc_name() const { 2898 if (collector_state()->in_concurrent_start_gc()) { 2899 return "Pause Young (Concurrent Start)"; 2900 } else if (collector_state()->in_young_only_phase()) { 2901 if (collector_state()->in_young_gc_before_mixed()) { 2902 return "Pause Young (Prepare Mixed)"; 2903 } else { 2904 return "Pause Young (Normal)"; 2905 } 2906 } else { 2907 return "Pause Young (Mixed)"; 2908 } 2909 } 2910 2911 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2912 assert_at_safepoint_on_vm_thread(); 2913 guarantee(!is_gc_active(), "collection is not reentrant"); 2914 2915 if (GCLocker::check_active_before_gc()) { 2916 return false; 2917 } 2918 2919 do_collection_pause_at_safepoint_helper(target_pause_time_ms); 2920 if (should_upgrade_to_full_gc(gc_cause())) { 2921 log_info(gc, ergo)("Attempting maximally compacting collection"); 2922 bool result = do_full_collection(false /* explicit gc */, 2923 true /* clear_all_soft_refs */); 2924 // do_full_collection only fails if blocked by GC locker, but 2925 // we've already checked for that above. 2926 assert(result, "invariant"); 2927 } 2928 return true; 2929 } 2930 2931 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) { 2932 GCIdMark gc_id_mark; 2933 2934 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2935 ResourceMark rm; 2936 2937 policy()->note_gc_start(); 2938 2939 _gc_timer_stw->register_gc_start(); 2940 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2941 2942 wait_for_root_region_scanning(); 2943 2944 print_heap_before_gc(); 2945 print_heap_regions(); 2946 trace_heap_before_gc(_gc_tracer_stw); 2947 2948 _verifier->verify_region_sets_optional(); 2949 _verifier->verify_dirty_young_regions(); 2950 2951 // We should not be doing concurrent start unless the concurrent mark thread is running 2952 if (!_cm_thread->should_terminate()) { 2953 // This call will decide whether this pause is a concurrent start 2954 // pause. If it is, in_concurrent_start_gc() will return true 2955 // for the duration of this pause. 2956 policy()->decide_on_conc_mark_initiation(); 2957 } 2958 2959 // We do not allow concurrent start to be piggy-backed on a mixed GC. 2960 assert(!collector_state()->in_concurrent_start_gc() || 2961 collector_state()->in_young_only_phase(), "sanity"); 2962 // We also do not allow mixed GCs during marking. 2963 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2964 2965 // Record whether this pause is a concurrent start. When the current 2966 // thread has completed its logging output and it's safe to signal 2967 // the CM thread, the flag's value in the policy has been reset. 2968 bool should_start_conc_mark = collector_state()->in_concurrent_start_gc(); 2969 if (should_start_conc_mark) { 2970 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2971 } 2972 2973 // Inner scope for scope based logging, timers, and stats collection 2974 { 2975 G1EvacuationInfo evacuation_info; 2976 2977 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2978 2979 GCTraceCPUTime tcpu; 2980 2981 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 2982 2983 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2984 workers()->active_workers(), 2985 Threads::number_of_non_daemon_threads()); 2986 active_workers = workers()->update_active_workers(active_workers); 2987 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2988 2989 G1MonitoringScope ms(g1mm(), 2990 false /* full_gc */, 2991 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2992 2993 G1HeapTransition heap_transition(this); 2994 2995 { 2996 IsGCActiveMark x; 2997 2998 gc_prologue(false); 2999 3000 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3001 verify_before_young_collection(verify_type); 3002 3003 { 3004 // The elapsed time induced by the start time below deliberately elides 3005 // the possible verification above. 3006 double sample_start_time_sec = os::elapsedTime(); 3007 3008 // Please see comment in g1CollectedHeap.hpp and 3009 // G1CollectedHeap::ref_processing_init() to see how 3010 // reference processing currently works in G1. 3011 _ref_processor_stw->enable_discovery(); 3012 3013 // We want to temporarily turn off discovery by the 3014 // CM ref processor, if necessary, and turn it back on 3015 // on again later if we do. Using a scoped 3016 // NoRefDiscovery object will do this. 3017 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3018 3019 policy()->record_collection_pause_start(sample_start_time_sec); 3020 3021 // Forget the current allocation region (we might even choose it to be part 3022 // of the collection set!). 3023 _allocator->release_mutator_alloc_regions(); 3024 3025 calculate_collection_set(evacuation_info, target_pause_time_ms); 3026 3027 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3028 G1ParScanThreadStateSet per_thread_states(this, 3029 &rdcqs, 3030 workers()->active_workers(), 3031 collection_set()->young_region_length(), 3032 collection_set()->optional_region_length()); 3033 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3034 3035 // Actually do the work... 3036 evacuate_initial_collection_set(&per_thread_states); 3037 3038 if (_collection_set.optional_region_length() != 0) { 3039 evacuate_optional_collection_set(&per_thread_states); 3040 } 3041 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3042 3043 start_new_collection_set(); 3044 3045 _survivor_evac_stats.adjust_desired_plab_sz(); 3046 _old_evac_stats.adjust_desired_plab_sz(); 3047 3048 if (should_start_conc_mark) { 3049 // We have to do this before we notify the CM threads that 3050 // they can start working to make sure that all the 3051 // appropriate initialization is done on the CM object. 3052 concurrent_mark()->post_concurrent_start(); 3053 // Note that we don't actually trigger the CM thread at 3054 // this point. We do that later when we're sure that 3055 // the current thread has completed its logging output. 3056 } 3057 3058 allocate_dummy_regions(); 3059 3060 _allocator->init_mutator_alloc_regions(); 3061 3062 expand_heap_after_young_collection(); 3063 3064 double sample_end_time_sec = os::elapsedTime(); 3065 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3066 policy()->record_collection_pause_end(pause_time_ms); 3067 } 3068 3069 verify_after_young_collection(verify_type); 3070 3071 gc_epilogue(false); 3072 } 3073 3074 // Print the remainder of the GC log output. 3075 if (evacuation_failed()) { 3076 log_info(gc)("To-space exhausted"); 3077 } 3078 3079 policy()->print_phases(); 3080 heap_transition.print(); 3081 3082 _hrm->verify_optional(); 3083 _verifier->verify_region_sets_optional(); 3084 3085 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3086 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3087 3088 print_heap_after_gc(); 3089 print_heap_regions(); 3090 trace_heap_after_gc(_gc_tracer_stw); 3091 3092 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3093 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3094 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3095 // before any GC notifications are raised. 3096 g1mm()->update_sizes(); 3097 3098 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3099 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3100 _gc_timer_stw->register_gc_end(); 3101 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3102 } 3103 // It should now be safe to tell the concurrent mark thread to start 3104 // without its logging output interfering with the logging output 3105 // that came from the pause. 3106 3107 if (should_start_conc_mark) { 3108 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3109 // thread(s) could be running concurrently with us. Make sure that anything 3110 // after this point does not assume that we are the only GC thread running. 3111 // Note: of course, the actual marking work will not start until the safepoint 3112 // itself is released in SuspendibleThreadSet::desynchronize(). 3113 do_concurrent_mark(); 3114 ConcurrentGCBreakpoints::notify_idle_to_active(); 3115 } 3116 } 3117 3118 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3119 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3120 workers()->run_task(&rsfp_task); 3121 } 3122 3123 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3124 double remove_self_forwards_start = os::elapsedTime(); 3125 3126 remove_self_forwarding_pointers(rdcqs); 3127 _preserved_marks_set.restore(workers()); 3128 3129 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3130 } 3131 3132 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3133 if (!_evacuation_failed) { 3134 _evacuation_failed = true; 3135 } 3136 3137 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3138 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3139 } 3140 3141 bool G1ParEvacuateFollowersClosure::offer_termination() { 3142 EventGCPhaseParallel event; 3143 G1ParScanThreadState* const pss = par_scan_state(); 3144 start_term_time(); 3145 const bool res = terminator()->offer_termination(); 3146 end_term_time(); 3147 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3148 return res; 3149 } 3150 3151 void G1ParEvacuateFollowersClosure::do_void() { 3152 EventGCPhaseParallel event; 3153 G1ParScanThreadState* const pss = par_scan_state(); 3154 pss->trim_queue(); 3155 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3156 do { 3157 EventGCPhaseParallel event; 3158 pss->steal_and_trim_queue(queues()); 3159 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3160 } while (!offer_termination()); 3161 } 3162 3163 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3164 bool class_unloading_occurred) { 3165 uint num_workers = workers()->active_workers(); 3166 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3167 workers()->run_task(&unlink_task); 3168 } 3169 3170 // Clean string dedup data structures. 3171 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3172 // record the durations of the phases. Hence the almost-copy. 3173 class G1StringDedupCleaningTask : public AbstractGangTask { 3174 BoolObjectClosure* _is_alive; 3175 OopClosure* _keep_alive; 3176 G1GCPhaseTimes* _phase_times; 3177 3178 public: 3179 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3180 OopClosure* keep_alive, 3181 G1GCPhaseTimes* phase_times) : 3182 AbstractGangTask("Partial Cleaning Task"), 3183 _is_alive(is_alive), 3184 _keep_alive(keep_alive), 3185 _phase_times(phase_times) 3186 { 3187 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3188 StringDedup::gc_prologue(true); 3189 } 3190 3191 ~G1StringDedupCleaningTask() { 3192 StringDedup::gc_epilogue(); 3193 } 3194 3195 void work(uint worker_id) { 3196 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3197 { 3198 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3199 StringDedupQueue::unlink_or_oops_do(&cl); 3200 } 3201 { 3202 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3203 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3204 } 3205 } 3206 }; 3207 3208 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3209 OopClosure* keep_alive, 3210 G1GCPhaseTimes* phase_times) { 3211 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3212 workers()->run_task(&cl); 3213 } 3214 3215 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3216 private: 3217 G1RedirtyCardsQueueSet* _qset; 3218 G1CollectedHeap* _g1h; 3219 BufferNode* volatile _nodes; 3220 3221 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3222 size_t buffer_size = _qset->buffer_size(); 3223 BufferNode* next = Atomic::load(&_nodes); 3224 while (next != NULL) { 3225 BufferNode* node = next; 3226 next = Atomic::cmpxchg(&_nodes, node, node->next()); 3227 if (next == node) { 3228 cl->apply_to_buffer(node, buffer_size, worker_id); 3229 next = node->next(); 3230 } 3231 } 3232 } 3233 3234 public: 3235 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3236 AbstractGangTask("Redirty Cards"), 3237 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3238 3239 virtual void work(uint worker_id) { 3240 G1GCPhaseTimes* p = _g1h->phase_times(); 3241 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3242 3243 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3244 par_apply(&cl, worker_id); 3245 3246 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3247 } 3248 }; 3249 3250 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3251 double redirty_logged_cards_start = os::elapsedTime(); 3252 3253 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3254 workers()->run_task(&redirty_task); 3255 3256 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3257 dcq.merge_bufferlists(rdcqs); 3258 3259 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3260 } 3261 3262 // Weak Reference Processing support 3263 3264 bool G1STWIsAliveClosure::do_object_b(oop p) { 3265 // An object is reachable if it is outside the collection set, 3266 // or is inside and copied. 3267 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3268 } 3269 3270 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3271 assert(obj != NULL, "must not be NULL"); 3272 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3273 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3274 // may falsely indicate that this is not the case here: however the collection set only 3275 // contains old regions when concurrent mark is not running. 3276 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3277 } 3278 3279 // Non Copying Keep Alive closure 3280 class G1KeepAliveClosure: public OopClosure { 3281 G1CollectedHeap*_g1h; 3282 public: 3283 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3284 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3285 void do_oop(oop* p) { 3286 oop obj = *p; 3287 assert(obj != NULL, "the caller should have filtered out NULL values"); 3288 3289 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3290 if (!region_attr.is_in_cset_or_humongous()) { 3291 return; 3292 } 3293 if (region_attr.is_in_cset()) { 3294 assert( obj->is_forwarded(), "invariant" ); 3295 *p = obj->forwardee(); 3296 } else { 3297 assert(!obj->is_forwarded(), "invariant" ); 3298 assert(region_attr.is_humongous(), 3299 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3300 _g1h->set_humongous_is_live(obj); 3301 } 3302 } 3303 }; 3304 3305 // Copying Keep Alive closure - can be called from both 3306 // serial and parallel code as long as different worker 3307 // threads utilize different G1ParScanThreadState instances 3308 // and different queues. 3309 3310 class G1CopyingKeepAliveClosure: public OopClosure { 3311 G1CollectedHeap* _g1h; 3312 G1ParScanThreadState* _par_scan_state; 3313 3314 public: 3315 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3316 G1ParScanThreadState* pss): 3317 _g1h(g1h), 3318 _par_scan_state(pss) 3319 {} 3320 3321 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3322 virtual void do_oop( oop* p) { do_oop_work(p); } 3323 3324 template <class T> void do_oop_work(T* p) { 3325 oop obj = RawAccess<>::oop_load(p); 3326 3327 if (_g1h->is_in_cset_or_humongous(obj)) { 3328 // If the referent object has been forwarded (either copied 3329 // to a new location or to itself in the event of an 3330 // evacuation failure) then we need to update the reference 3331 // field and, if both reference and referent are in the G1 3332 // heap, update the RSet for the referent. 3333 // 3334 // If the referent has not been forwarded then we have to keep 3335 // it alive by policy. Therefore we have copy the referent. 3336 // 3337 // When the queue is drained (after each phase of reference processing) 3338 // the object and it's followers will be copied, the reference field set 3339 // to point to the new location, and the RSet updated. 3340 _par_scan_state->push_on_queue(ScannerTask(p)); 3341 } 3342 } 3343 }; 3344 3345 // Serial drain queue closure. Called as the 'complete_gc' 3346 // closure for each discovered list in some of the 3347 // reference processing phases. 3348 3349 class G1STWDrainQueueClosure: public VoidClosure { 3350 protected: 3351 G1CollectedHeap* _g1h; 3352 G1ParScanThreadState* _par_scan_state; 3353 3354 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3355 3356 public: 3357 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3358 _g1h(g1h), 3359 _par_scan_state(pss) 3360 { } 3361 3362 void do_void() { 3363 G1ParScanThreadState* const pss = par_scan_state(); 3364 pss->trim_queue(); 3365 } 3366 }; 3367 3368 // Parallel Reference Processing closures 3369 3370 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3371 // processing during G1 evacuation pauses. 3372 3373 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3374 private: 3375 G1CollectedHeap* _g1h; 3376 G1ParScanThreadStateSet* _pss; 3377 G1ScannerTasksQueueSet* _queues; 3378 WorkGang* _workers; 3379 3380 public: 3381 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3382 G1ParScanThreadStateSet* per_thread_states, 3383 WorkGang* workers, 3384 G1ScannerTasksQueueSet *task_queues) : 3385 _g1h(g1h), 3386 _pss(per_thread_states), 3387 _queues(task_queues), 3388 _workers(workers) 3389 { 3390 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3391 } 3392 3393 // Executes the given task using concurrent marking worker threads. 3394 virtual void execute(ProcessTask& task, uint ergo_workers); 3395 }; 3396 3397 // Gang task for possibly parallel reference processing 3398 3399 class G1STWRefProcTaskProxy: public AbstractGangTask { 3400 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3401 ProcessTask& _proc_task; 3402 G1CollectedHeap* _g1h; 3403 G1ParScanThreadStateSet* _pss; 3404 G1ScannerTasksQueueSet* _task_queues; 3405 TaskTerminator* _terminator; 3406 3407 public: 3408 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3409 G1CollectedHeap* g1h, 3410 G1ParScanThreadStateSet* per_thread_states, 3411 G1ScannerTasksQueueSet *task_queues, 3412 TaskTerminator* terminator) : 3413 AbstractGangTask("Process reference objects in parallel"), 3414 _proc_task(proc_task), 3415 _g1h(g1h), 3416 _pss(per_thread_states), 3417 _task_queues(task_queues), 3418 _terminator(terminator) 3419 {} 3420 3421 virtual void work(uint worker_id) { 3422 // The reference processing task executed by a single worker. 3423 ResourceMark rm; 3424 HandleMark hm; 3425 3426 G1STWIsAliveClosure is_alive(_g1h); 3427 3428 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3429 pss->set_ref_discoverer(NULL); 3430 3431 // Keep alive closure. 3432 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3433 3434 // Complete GC closure 3435 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3436 3437 // Call the reference processing task's work routine. 3438 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3439 3440 // Note we cannot assert that the refs array is empty here as not all 3441 // of the processing tasks (specifically phase2 - pp2_work) execute 3442 // the complete_gc closure (which ordinarily would drain the queue) so 3443 // the queue may not be empty. 3444 } 3445 }; 3446 3447 // Driver routine for parallel reference processing. 3448 // Creates an instance of the ref processing gang 3449 // task and has the worker threads execute it. 3450 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3451 assert(_workers != NULL, "Need parallel worker threads."); 3452 3453 assert(_workers->active_workers() >= ergo_workers, 3454 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3455 ergo_workers, _workers->active_workers()); 3456 TaskTerminator terminator(ergo_workers, _queues); 3457 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3458 3459 _workers->run_task(&proc_task_proxy, ergo_workers); 3460 } 3461 3462 // End of weak reference support closures 3463 3464 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3465 double ref_proc_start = os::elapsedTime(); 3466 3467 ReferenceProcessor* rp = _ref_processor_stw; 3468 assert(rp->discovery_enabled(), "should have been enabled"); 3469 3470 // Closure to test whether a referent is alive. 3471 G1STWIsAliveClosure is_alive(this); 3472 3473 // Even when parallel reference processing is enabled, the processing 3474 // of JNI refs is serial and performed serially by the current thread 3475 // rather than by a worker. The following PSS will be used for processing 3476 // JNI refs. 3477 3478 // Use only a single queue for this PSS. 3479 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3480 pss->set_ref_discoverer(NULL); 3481 assert(pss->queue_is_empty(), "pre-condition"); 3482 3483 // Keep alive closure. 3484 G1CopyingKeepAliveClosure keep_alive(this, pss); 3485 3486 // Serial Complete GC closure 3487 G1STWDrainQueueClosure drain_queue(this, pss); 3488 3489 // Setup the soft refs policy... 3490 rp->setup_policy(false); 3491 3492 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3493 3494 ReferenceProcessorStats stats; 3495 if (!rp->processing_is_mt()) { 3496 // Serial reference processing... 3497 stats = rp->process_discovered_references(&is_alive, 3498 &keep_alive, 3499 &drain_queue, 3500 NULL, 3501 pt); 3502 } else { 3503 uint no_of_gc_workers = workers()->active_workers(); 3504 3505 // Parallel reference processing 3506 assert(no_of_gc_workers <= rp->max_num_queues(), 3507 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3508 no_of_gc_workers, rp->max_num_queues()); 3509 3510 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3511 stats = rp->process_discovered_references(&is_alive, 3512 &keep_alive, 3513 &drain_queue, 3514 &par_task_executor, 3515 pt); 3516 } 3517 3518 _gc_tracer_stw->report_gc_reference_stats(stats); 3519 3520 // We have completed copying any necessary live referent objects. 3521 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3522 3523 make_pending_list_reachable(); 3524 3525 assert(!rp->discovery_enabled(), "Postcondition"); 3526 rp->verify_no_references_recorded(); 3527 3528 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3529 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3530 } 3531 3532 void G1CollectedHeap::make_pending_list_reachable() { 3533 if (collector_state()->in_concurrent_start_gc()) { 3534 oop pll_head = Universe::reference_pending_list(); 3535 if (pll_head != NULL) { 3536 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3537 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3538 } 3539 } 3540 } 3541 3542 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3543 Ticks start = Ticks::now(); 3544 per_thread_states->flush(); 3545 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds()); 3546 } 3547 3548 class G1PrepareEvacuationTask : public AbstractGangTask { 3549 class G1PrepareRegionsClosure : public HeapRegionClosure { 3550 G1CollectedHeap* _g1h; 3551 G1PrepareEvacuationTask* _parent_task; 3552 size_t _worker_humongous_total; 3553 size_t _worker_humongous_candidates; 3554 3555 bool humongous_region_is_candidate(HeapRegion* region) const { 3556 assert(region->is_starts_humongous(), "Must start a humongous object"); 3557 3558 oop obj = oop(region->bottom()); 3559 3560 // Dead objects cannot be eager reclaim candidates. Due to class 3561 // unloading it is unsafe to query their classes so we return early. 3562 if (_g1h->is_obj_dead(obj, region)) { 3563 return false; 3564 } 3565 3566 // If we do not have a complete remembered set for the region, then we can 3567 // not be sure that we have all references to it. 3568 if (!region->rem_set()->is_complete()) { 3569 return false; 3570 } 3571 // Candidate selection must satisfy the following constraints 3572 // while concurrent marking is in progress: 3573 // 3574 // * In order to maintain SATB invariants, an object must not be 3575 // reclaimed if it was allocated before the start of marking and 3576 // has not had its references scanned. Such an object must have 3577 // its references (including type metadata) scanned to ensure no 3578 // live objects are missed by the marking process. Objects 3579 // allocated after the start of concurrent marking don't need to 3580 // be scanned. 3581 // 3582 // * An object must not be reclaimed if it is on the concurrent 3583 // mark stack. Objects allocated after the start of concurrent 3584 // marking are never pushed on the mark stack. 3585 // 3586 // Nominating only objects allocated after the start of concurrent 3587 // marking is sufficient to meet both constraints. This may miss 3588 // some objects that satisfy the constraints, but the marking data 3589 // structures don't support efficiently performing the needed 3590 // additional tests or scrubbing of the mark stack. 3591 // 3592 // However, we presently only nominate is_typeArray() objects. 3593 // A humongous object containing references induces remembered 3594 // set entries on other regions. In order to reclaim such an 3595 // object, those remembered sets would need to be cleaned up. 3596 // 3597 // We also treat is_typeArray() objects specially, allowing them 3598 // to be reclaimed even if allocated before the start of 3599 // concurrent mark. For this we rely on mark stack insertion to 3600 // exclude is_typeArray() objects, preventing reclaiming an object 3601 // that is in the mark stack. We also rely on the metadata for 3602 // such objects to be built-in and so ensured to be kept live. 3603 // Frequent allocation and drop of large binary blobs is an 3604 // important use case for eager reclaim, and this special handling 3605 // may reduce needed headroom. 3606 3607 return obj->is_typeArray() && 3608 _g1h->is_potential_eager_reclaim_candidate(region); 3609 } 3610 3611 public: 3612 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) : 3613 _g1h(g1h), 3614 _parent_task(parent_task), 3615 _worker_humongous_total(0), 3616 _worker_humongous_candidates(0) { } 3617 3618 ~G1PrepareRegionsClosure() { 3619 _parent_task->add_humongous_candidates(_worker_humongous_candidates); 3620 _parent_task->add_humongous_total(_worker_humongous_total); 3621 } 3622 3623 virtual bool do_heap_region(HeapRegion* hr) { 3624 // First prepare the region for scanning 3625 _g1h->rem_set()->prepare_region_for_scan(hr); 3626 3627 // Now check if region is a humongous candidate 3628 if (!hr->is_starts_humongous()) { 3629 _g1h->register_region_with_region_attr(hr); 3630 return false; 3631 } 3632 3633 uint index = hr->hrm_index(); 3634 if (humongous_region_is_candidate(hr)) { 3635 _g1h->set_humongous_reclaim_candidate(index, true); 3636 _g1h->register_humongous_region_with_region_attr(index); 3637 _worker_humongous_candidates++; 3638 // We will later handle the remembered sets of these regions. 3639 } else { 3640 _g1h->set_humongous_reclaim_candidate(index, false); 3641 _g1h->register_region_with_region_attr(hr); 3642 } 3643 _worker_humongous_total++; 3644 3645 return false; 3646 } 3647 }; 3648 3649 G1CollectedHeap* _g1h; 3650 HeapRegionClaimer _claimer; 3651 volatile size_t _humongous_total; 3652 volatile size_t _humongous_candidates; 3653 public: 3654 G1PrepareEvacuationTask(G1CollectedHeap* g1h) : 3655 AbstractGangTask("Prepare Evacuation"), 3656 _g1h(g1h), 3657 _claimer(_g1h->workers()->active_workers()), 3658 _humongous_total(0), 3659 _humongous_candidates(0) { } 3660 3661 ~G1PrepareEvacuationTask() { 3662 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0); 3663 } 3664 3665 void work(uint worker_id) { 3666 G1PrepareRegionsClosure cl(_g1h, this); 3667 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id); 3668 } 3669 3670 void add_humongous_candidates(size_t candidates) { 3671 Atomic::add(&_humongous_candidates, candidates); 3672 } 3673 3674 void add_humongous_total(size_t total) { 3675 Atomic::add(&_humongous_total, total); 3676 } 3677 3678 size_t humongous_candidates() { 3679 return _humongous_candidates; 3680 } 3681 3682 size_t humongous_total() { 3683 return _humongous_total; 3684 } 3685 }; 3686 3687 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3688 _bytes_used_during_gc = 0; 3689 3690 _expand_heap_after_alloc_failure = true; 3691 _evacuation_failed = false; 3692 3693 // Disable the hot card cache. 3694 _hot_card_cache->reset_hot_cache_claimed_index(); 3695 _hot_card_cache->set_use_cache(false); 3696 3697 // Initialize the GC alloc regions. 3698 _allocator->init_gc_alloc_regions(evacuation_info); 3699 3700 { 3701 Ticks start = Ticks::now(); 3702 rem_set()->prepare_for_scan_heap_roots(); 3703 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3704 } 3705 3706 { 3707 G1PrepareEvacuationTask g1_prep_task(this); 3708 Tickspan task_time = run_task_timed(&g1_prep_task); 3709 3710 phase_times()->record_register_regions(task_time.seconds() * 1000.0, 3711 g1_prep_task.humongous_total(), 3712 g1_prep_task.humongous_candidates()); 3713 } 3714 3715 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3716 _preserved_marks_set.assert_empty(); 3717 3718 #if COMPILER2_OR_JVMCI 3719 DerivedPointerTable::clear(); 3720 #endif 3721 3722 // Concurrent start needs claim bits to keep track of the marked-through CLDs. 3723 if (collector_state()->in_concurrent_start_gc()) { 3724 concurrent_mark()->pre_concurrent_start(); 3725 3726 double start_clear_claimed_marks = os::elapsedTime(); 3727 3728 ClassLoaderDataGraph::clear_claimed_marks(); 3729 3730 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3731 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3732 } 3733 3734 // Should G1EvacuationFailureALot be in effect for this GC? 3735 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3736 } 3737 3738 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3739 protected: 3740 G1CollectedHeap* _g1h; 3741 G1ParScanThreadStateSet* _per_thread_states; 3742 G1ScannerTasksQueueSet* _task_queues; 3743 TaskTerminator _terminator; 3744 uint _num_workers; 3745 3746 void evacuate_live_objects(G1ParScanThreadState* pss, 3747 uint worker_id, 3748 G1GCPhaseTimes::GCParPhases objcopy_phase, 3749 G1GCPhaseTimes::GCParPhases termination_phase) { 3750 G1GCPhaseTimes* p = _g1h->phase_times(); 3751 3752 Ticks start = Ticks::now(); 3753 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase); 3754 cl.do_void(); 3755 3756 assert(pss->queue_is_empty(), "should be empty"); 3757 3758 Tickspan evac_time = (Ticks::now() - start); 3759 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3760 3761 if (termination_phase == G1GCPhaseTimes::Termination) { 3762 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3763 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3764 } else { 3765 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3766 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3767 } 3768 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3769 } 3770 3771 virtual void start_work(uint worker_id) { } 3772 3773 virtual void end_work(uint worker_id) { } 3774 3775 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3776 3777 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3778 3779 public: 3780 G1EvacuateRegionsBaseTask(const char* name, 3781 G1ParScanThreadStateSet* per_thread_states, 3782 G1ScannerTasksQueueSet* task_queues, 3783 uint num_workers) : 3784 AbstractGangTask(name), 3785 _g1h(G1CollectedHeap::heap()), 3786 _per_thread_states(per_thread_states), 3787 _task_queues(task_queues), 3788 _terminator(num_workers, _task_queues), 3789 _num_workers(num_workers) 3790 { } 3791 3792 void work(uint worker_id) { 3793 start_work(worker_id); 3794 3795 { 3796 ResourceMark rm; 3797 HandleMark hm; 3798 3799 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3800 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3801 3802 scan_roots(pss, worker_id); 3803 evacuate_live_objects(pss, worker_id); 3804 } 3805 3806 end_work(worker_id); 3807 } 3808 }; 3809 3810 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3811 G1RootProcessor* _root_processor; 3812 3813 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3814 _root_processor->evacuate_roots(pss, worker_id); 3815 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3816 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3817 } 3818 3819 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3820 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3821 } 3822 3823 void start_work(uint worker_id) { 3824 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3825 } 3826 3827 void end_work(uint worker_id) { 3828 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3829 } 3830 3831 public: 3832 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3833 G1ParScanThreadStateSet* per_thread_states, 3834 G1ScannerTasksQueueSet* task_queues, 3835 G1RootProcessor* root_processor, 3836 uint num_workers) : 3837 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3838 _root_processor(root_processor) 3839 { } 3840 }; 3841 3842 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3843 G1GCPhaseTimes* p = phase_times(); 3844 3845 { 3846 Ticks start = Ticks::now(); 3847 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3848 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3849 } 3850 3851 Tickspan task_time; 3852 const uint num_workers = workers()->active_workers(); 3853 3854 Ticks start_processing = Ticks::now(); 3855 { 3856 G1RootProcessor root_processor(this, num_workers); 3857 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3858 task_time = run_task_timed(&g1_par_task); 3859 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3860 // To extract its code root fixup time we measure total time of this scope and 3861 // subtract from the time the WorkGang task took. 3862 } 3863 Tickspan total_processing = Ticks::now() - start_processing; 3864 3865 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3866 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3867 } 3868 3869 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3870 3871 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3872 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3873 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3874 } 3875 3876 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3877 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3878 } 3879 3880 public: 3881 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3882 G1ScannerTasksQueueSet* queues, 3883 uint num_workers) : 3884 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3885 } 3886 }; 3887 3888 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3889 class G1MarkScope : public MarkScope { }; 3890 3891 Tickspan task_time; 3892 3893 Ticks start_processing = Ticks::now(); 3894 { 3895 G1MarkScope code_mark_scope; 3896 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3897 task_time = run_task_timed(&task); 3898 // See comment in evacuate_collection_set() for the reason of the scope. 3899 } 3900 Tickspan total_processing = Ticks::now() - start_processing; 3901 3902 G1GCPhaseTimes* p = phase_times(); 3903 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3904 } 3905 3906 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3907 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3908 3909 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3910 3911 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3912 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3913 3914 if (time_left_ms < 0 || 3915 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3916 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3917 _collection_set.optional_region_length(), time_left_ms); 3918 break; 3919 } 3920 3921 { 3922 Ticks start = Ticks::now(); 3923 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3924 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3925 } 3926 3927 { 3928 Ticks start = Ticks::now(); 3929 evacuate_next_optional_regions(per_thread_states); 3930 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3931 } 3932 } 3933 3934 _collection_set.abandon_optional_collection_set(per_thread_states); 3935 } 3936 3937 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3938 G1RedirtyCardsQueueSet* rdcqs, 3939 G1ParScanThreadStateSet* per_thread_states) { 3940 G1GCPhaseTimes* p = phase_times(); 3941 3942 rem_set()->cleanup_after_scan_heap_roots(); 3943 3944 // Process any discovered reference objects - we have 3945 // to do this _before_ we retire the GC alloc regions 3946 // as we may have to copy some 'reachable' referent 3947 // objects (and their reachable sub-graphs) that were 3948 // not copied during the pause. 3949 process_discovered_references(per_thread_states); 3950 3951 G1STWIsAliveClosure is_alive(this); 3952 G1KeepAliveClosure keep_alive(this); 3953 3954 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times()); 3955 3956 if (G1StringDedup::is_enabled()) { 3957 double string_dedup_time_ms = os::elapsedTime(); 3958 3959 string_dedup_cleaning(&is_alive, &keep_alive, p); 3960 3961 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3962 p->record_string_deduplication_time(string_cleanup_time_ms); 3963 } 3964 3965 _allocator->release_gc_alloc_regions(evacuation_info); 3966 3967 if (evacuation_failed()) { 3968 restore_after_evac_failure(rdcqs); 3969 3970 // Reset the G1EvacuationFailureALot counters and flags 3971 NOT_PRODUCT(reset_evacuation_should_fail();) 3972 3973 double recalculate_used_start = os::elapsedTime(); 3974 set_used(recalculate_used()); 3975 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3976 3977 if (_archive_allocator != NULL) { 3978 _archive_allocator->clear_used(); 3979 } 3980 for (uint i = 0; i < ParallelGCThreads; i++) { 3981 if (_evacuation_failed_info_array[i].has_failed()) { 3982 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3983 } 3984 } 3985 } else { 3986 // The "used" of the the collection set have already been subtracted 3987 // when they were freed. Add in the bytes used. 3988 increase_used(_bytes_used_during_gc); 3989 } 3990 3991 _preserved_marks_set.assert_empty(); 3992 3993 merge_per_thread_state_info(per_thread_states); 3994 3995 // Reset and re-enable the hot card cache. 3996 // Note the counts for the cards in the regions in the 3997 // collection set are reset when the collection set is freed. 3998 _hot_card_cache->reset_hot_cache(); 3999 _hot_card_cache->set_use_cache(true); 4000 4001 purge_code_root_memory(); 4002 4003 redirty_logged_cards(rdcqs); 4004 4005 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4006 4007 eagerly_reclaim_humongous_regions(); 4008 4009 record_obj_copy_mem_stats(); 4010 4011 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4012 evacuation_info.set_bytes_used(_bytes_used_during_gc); 4013 4014 #if COMPILER2_OR_JVMCI 4015 double start = os::elapsedTime(); 4016 DerivedPointerTable::update_pointers(); 4017 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4018 #endif 4019 policy()->print_age_table(); 4020 } 4021 4022 void G1CollectedHeap::record_obj_copy_mem_stats() { 4023 policy()->old_gen_alloc_tracker()-> 4024 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4025 4026 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4027 create_g1_evac_summary(&_old_evac_stats)); 4028 } 4029 4030 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 4031 assert(!hr->is_free(), "the region should not be free"); 4032 assert(!hr->is_empty(), "the region should not be empty"); 4033 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4034 4035 if (G1VerifyBitmaps) { 4036 MemRegion mr(hr->bottom(), hr->end()); 4037 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4038 } 4039 4040 // Clear the card counts for this region. 4041 // Note: we only need to do this if the region is not young 4042 // (since we don't refine cards in young regions). 4043 if (!hr->is_young()) { 4044 _hot_card_cache->reset_card_counts(hr); 4045 } 4046 4047 // Reset region metadata to allow reuse. 4048 hr->hr_clear(true /* clear_space */); 4049 _policy->remset_tracker()->update_at_free(hr); 4050 4051 if (free_list != NULL) { 4052 free_list->add_ordered(hr); 4053 } 4054 } 4055 4056 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4057 FreeRegionList* free_list) { 4058 assert(hr->is_humongous(), "this is only for humongous regions"); 4059 assert(free_list != NULL, "pre-condition"); 4060 hr->clear_humongous(); 4061 free_region(hr, free_list); 4062 } 4063 4064 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4065 const uint humongous_regions_removed) { 4066 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4067 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4068 _old_set.bulk_remove(old_regions_removed); 4069 _humongous_set.bulk_remove(humongous_regions_removed); 4070 } 4071 4072 } 4073 4074 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4075 assert(list != NULL, "list can't be null"); 4076 if (!list->is_empty()) { 4077 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4078 _hrm->insert_list_into_free_list(list); 4079 } 4080 } 4081 4082 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4083 decrease_used(bytes); 4084 } 4085 4086 class G1FreeCollectionSetTask : public AbstractGangTask { 4087 // Helper class to keep statistics for the collection set freeing 4088 class FreeCSetStats { 4089 size_t _before_used_bytes; // Usage in regions successfully evacutate 4090 size_t _after_used_bytes; // Usage in regions failing evacuation 4091 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old 4092 size_t _failure_used_words; // Live size in failed regions 4093 size_t _failure_waste_words; // Wasted size in failed regions 4094 size_t _rs_length; // Remembered set size 4095 uint _regions_freed; // Number of regions freed 4096 public: 4097 FreeCSetStats() : 4098 _before_used_bytes(0), 4099 _after_used_bytes(0), 4100 _bytes_allocated_in_old_since_last_gc(0), 4101 _failure_used_words(0), 4102 _failure_waste_words(0), 4103 _rs_length(0), 4104 _regions_freed(0) { } 4105 4106 void merge_stats(FreeCSetStats* other) { 4107 assert(other != NULL, "invariant"); 4108 _before_used_bytes += other->_before_used_bytes; 4109 _after_used_bytes += other->_after_used_bytes; 4110 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc; 4111 _failure_used_words += other->_failure_used_words; 4112 _failure_waste_words += other->_failure_waste_words; 4113 _rs_length += other->_rs_length; 4114 _regions_freed += other->_regions_freed; 4115 } 4116 4117 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) { 4118 evacuation_info->set_regions_freed(_regions_freed); 4119 evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4120 4121 g1h->decrement_summary_bytes(_before_used_bytes); 4122 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4123 4124 G1Policy *policy = g1h->policy(); 4125 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4126 policy->record_rs_length(_rs_length); 4127 policy->cset_regions_freed(); 4128 } 4129 4130 void account_failed_region(HeapRegion* r) { 4131 size_t used_words = r->marked_bytes() / HeapWordSize; 4132 _failure_used_words += used_words; 4133 _failure_waste_words += HeapRegion::GrainWords - used_words; 4134 _after_used_bytes += r->used(); 4135 4136 // When moving a young gen region to old gen, we "allocate" that whole 4137 // region there. This is in addition to any already evacuated objects. 4138 // Notify the policy about that. Old gen regions do not cause an 4139 // additional allocation: both the objects still in the region and the 4140 // ones already moved are accounted for elsewhere. 4141 if (r->is_young()) { 4142 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4143 } 4144 } 4145 4146 void account_evacuated_region(HeapRegion* r) { 4147 _before_used_bytes += r->used(); 4148 _regions_freed += 1; 4149 } 4150 4151 void account_rs_length(HeapRegion* r) { 4152 _rs_length += r->rem_set()->occupied(); 4153 } 4154 }; 4155 4156 // Closure applied to all regions in the collection set. 4157 class FreeCSetClosure : public HeapRegionClosure { 4158 // Helper to send JFR events for regions. 4159 class JFREventForRegion { 4160 EventGCPhaseParallel _event; 4161 public: 4162 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() { 4163 _event.set_gcId(GCId::current()); 4164 _event.set_gcWorkerId(worker_id); 4165 if (region->is_young()) { 4166 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4167 } else { 4168 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4169 } 4170 } 4171 4172 ~JFREventForRegion() { 4173 _event.commit(); 4174 } 4175 }; 4176 4177 // Helper to do timing for region work. 4178 class TimerForRegion { 4179 Tickspan& _time; 4180 Ticks _start_time; 4181 public: 4182 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { } 4183 ~TimerForRegion() { 4184 _time += Ticks::now() - _start_time; 4185 } 4186 }; 4187 4188 // FreeCSetClosure members 4189 G1CollectedHeap* _g1h; 4190 const size_t* _surviving_young_words; 4191 uint _worker_id; 4192 Tickspan _young_time; 4193 Tickspan _non_young_time; 4194 FreeCSetStats* _stats; 4195 4196 void assert_in_cset(HeapRegion* r) { 4197 assert(r->young_index_in_cset() != 0 && 4198 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(), 4199 "Young index %u is wrong for region %u of type %s with %u young regions", 4200 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length()); 4201 } 4202 4203 void handle_evacuated_region(HeapRegion* r) { 4204 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4205 stats()->account_evacuated_region(r); 4206 4207 // Free the region and and its remembered set. 4208 _g1h->free_region(r, NULL); 4209 } 4210 4211 void handle_failed_region(HeapRegion* r) { 4212 // Do some allocation statistics accounting. Regions that failed evacuation 4213 // are always made old, so there is no need to update anything in the young 4214 // gen statistics, but we need to update old gen statistics. 4215 stats()->account_failed_region(r); 4216 4217 // Update the region state due to the failed evacuation. 4218 r->handle_evacuation_failure(); 4219 4220 // Add region to old set, need to hold lock. 4221 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4222 _g1h->old_set_add(r); 4223 } 4224 4225 Tickspan& timer_for_region(HeapRegion* r) { 4226 return r->is_young() ? _young_time : _non_young_time; 4227 } 4228 4229 FreeCSetStats* stats() { 4230 return _stats; 4231 } 4232 public: 4233 FreeCSetClosure(const size_t* surviving_young_words, 4234 uint worker_id, 4235 FreeCSetStats* stats) : 4236 HeapRegionClosure(), 4237 _g1h(G1CollectedHeap::heap()), 4238 _surviving_young_words(surviving_young_words), 4239 _worker_id(worker_id), 4240 _young_time(), 4241 _non_young_time(), 4242 _stats(stats) { } 4243 4244 virtual bool do_heap_region(HeapRegion* r) { 4245 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index()); 4246 JFREventForRegion event(r, _worker_id); 4247 TimerForRegion timer(timer_for_region(r)); 4248 4249 _g1h->clear_region_attr(r); 4250 stats()->account_rs_length(r); 4251 4252 if (r->is_young()) { 4253 assert_in_cset(r); 4254 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]); 4255 } 4256 4257 if (r->evacuation_failed()) { 4258 handle_failed_region(r); 4259 } else { 4260 handle_evacuated_region(r); 4261 } 4262 assert(!_g1h->is_on_master_free_list(r), "sanity"); 4263 4264 return false; 4265 } 4266 4267 void report_timing(Tickspan parallel_time) { 4268 G1GCPhaseTimes* pt = _g1h->phase_times(); 4269 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds()); 4270 if (_young_time.value() > 0) { 4271 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds()); 4272 } 4273 if (_non_young_time.value() > 0) { 4274 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds()); 4275 } 4276 } 4277 }; 4278 4279 // G1FreeCollectionSetTask members 4280 G1CollectedHeap* _g1h; 4281 G1EvacuationInfo* _evacuation_info; 4282 FreeCSetStats* _worker_stats; 4283 HeapRegionClaimer _claimer; 4284 const size_t* _surviving_young_words; 4285 uint _active_workers; 4286 4287 FreeCSetStats* worker_stats(uint worker) { 4288 return &_worker_stats[worker]; 4289 } 4290 4291 void report_statistics() { 4292 // Merge the accounting 4293 FreeCSetStats total_stats; 4294 for (uint worker = 0; worker < _active_workers; worker++) { 4295 total_stats.merge_stats(worker_stats(worker)); 4296 } 4297 total_stats.report(_g1h, _evacuation_info); 4298 } 4299 4300 public: 4301 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) : 4302 AbstractGangTask("G1 Free Collection Set"), 4303 _g1h(G1CollectedHeap::heap()), 4304 _evacuation_info(evacuation_info), 4305 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)), 4306 _claimer(active_workers), 4307 _surviving_young_words(surviving_young_words), 4308 _active_workers(active_workers) { 4309 for (uint worker = 0; worker < active_workers; worker++) { 4310 ::new (&_worker_stats[worker]) FreeCSetStats(); 4311 } 4312 } 4313 4314 ~G1FreeCollectionSetTask() { 4315 Ticks serial_time = Ticks::now(); 4316 report_statistics(); 4317 for (uint worker = 0; worker < _active_workers; worker++) { 4318 _worker_stats[worker].~FreeCSetStats(); 4319 } 4320 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats); 4321 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0); 4322 } 4323 4324 virtual void work(uint worker_id) { 4325 EventGCPhaseParallel event; 4326 Ticks start = Ticks::now(); 4327 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id)); 4328 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id); 4329 4330 // Report the total parallel time along with some more detailed metrics. 4331 cl.report_timing(Ticks::now() - start); 4332 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet)); 4333 } 4334 }; 4335 4336 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4337 _eden.clear(); 4338 4339 // The free collections set is split up in two tasks, the first 4340 // frees the collection set and records what regions are free, 4341 // and the second one rebuilds the free list. This proved to be 4342 // more efficient than adding a sorted list to another. 4343 4344 Ticks free_cset_start_time = Ticks::now(); 4345 { 4346 uint const num_cs_regions = _collection_set.region_length(); 4347 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers()); 4348 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers); 4349 4350 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)", 4351 cl.name(), num_workers, num_cs_regions, num_regions()); 4352 workers()->run_task(&cl, num_workers); 4353 } 4354 4355 Ticks free_cset_end_time = Ticks::now(); 4356 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0); 4357 4358 // Now rebuild the free region list. 4359 hrm()->rebuild_free_list(workers()); 4360 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0); 4361 4362 collection_set->clear(); 4363 } 4364 4365 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4366 private: 4367 FreeRegionList* _free_region_list; 4368 HeapRegionSet* _proxy_set; 4369 uint _humongous_objects_reclaimed; 4370 uint _humongous_regions_reclaimed; 4371 size_t _freed_bytes; 4372 public: 4373 4374 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4375 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4376 } 4377 4378 virtual bool do_heap_region(HeapRegion* r) { 4379 if (!r->is_starts_humongous()) { 4380 return false; 4381 } 4382 4383 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4384 4385 oop obj = (oop)r->bottom(); 4386 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4387 4388 // The following checks whether the humongous object is live are sufficient. 4389 // The main additional check (in addition to having a reference from the roots 4390 // or the young gen) is whether the humongous object has a remembered set entry. 4391 // 4392 // A humongous object cannot be live if there is no remembered set for it 4393 // because: 4394 // - there can be no references from within humongous starts regions referencing 4395 // the object because we never allocate other objects into them. 4396 // (I.e. there are no intra-region references that may be missed by the 4397 // remembered set) 4398 // - as soon there is a remembered set entry to the humongous starts region 4399 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4400 // until the end of a concurrent mark. 4401 // 4402 // It is not required to check whether the object has been found dead by marking 4403 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4404 // all objects allocated during that time are considered live. 4405 // SATB marking is even more conservative than the remembered set. 4406 // So if at this point in the collection there is no remembered set entry, 4407 // nobody has a reference to it. 4408 // At the start of collection we flush all refinement logs, and remembered sets 4409 // are completely up-to-date wrt to references to the humongous object. 4410 // 4411 // Other implementation considerations: 4412 // - never consider object arrays at this time because they would pose 4413 // considerable effort for cleaning up the the remembered sets. This is 4414 // required because stale remembered sets might reference locations that 4415 // are currently allocated into. 4416 uint region_idx = r->hrm_index(); 4417 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4418 !r->rem_set()->is_empty()) { 4419 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", 4420 region_idx, 4421 (size_t)obj->size() * HeapWordSize, 4422 p2i(r->bottom()), 4423 r->rem_set()->occupied(), 4424 r->rem_set()->strong_code_roots_list_length(), 4425 next_bitmap->is_marked(r->bottom()), 4426 g1h->is_humongous_reclaim_candidate(region_idx), 4427 obj->is_typeArray() 4428 ); 4429 return false; 4430 } 4431 4432 guarantee(obj->is_typeArray(), 4433 "Only eagerly reclaiming type arrays is supported, but the object " 4434 PTR_FORMAT " is not.", p2i(r->bottom())); 4435 4436 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", 4437 region_idx, 4438 (size_t)obj->size() * HeapWordSize, 4439 p2i(r->bottom()), 4440 r->rem_set()->occupied(), 4441 r->rem_set()->strong_code_roots_list_length(), 4442 next_bitmap->is_marked(r->bottom()), 4443 g1h->is_humongous_reclaim_candidate(region_idx), 4444 obj->is_typeArray() 4445 ); 4446 4447 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4448 cm->humongous_object_eagerly_reclaimed(r); 4449 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4450 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4451 region_idx, 4452 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4453 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4454 _humongous_objects_reclaimed++; 4455 do { 4456 HeapRegion* next = g1h->next_region_in_humongous(r); 4457 _freed_bytes += r->used(); 4458 r->set_containing_set(NULL); 4459 _humongous_regions_reclaimed++; 4460 g1h->free_humongous_region(r, _free_region_list); 4461 r = next; 4462 } while (r != NULL); 4463 4464 return false; 4465 } 4466 4467 uint humongous_objects_reclaimed() { 4468 return _humongous_objects_reclaimed; 4469 } 4470 4471 uint humongous_regions_reclaimed() { 4472 return _humongous_regions_reclaimed; 4473 } 4474 4475 size_t bytes_freed() const { 4476 return _freed_bytes; 4477 } 4478 }; 4479 4480 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4481 assert_at_safepoint_on_vm_thread(); 4482 4483 if (!G1EagerReclaimHumongousObjects || 4484 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4485 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4486 return; 4487 } 4488 4489 double start_time = os::elapsedTime(); 4490 4491 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4492 4493 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4494 heap_region_iterate(&cl); 4495 4496 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4497 4498 G1HRPrinter* hrp = hr_printer(); 4499 if (hrp->is_active()) { 4500 FreeRegionListIterator iter(&local_cleanup_list); 4501 while (iter.more_available()) { 4502 HeapRegion* hr = iter.get_next(); 4503 hrp->cleanup(hr); 4504 } 4505 } 4506 4507 prepend_to_freelist(&local_cleanup_list); 4508 decrement_summary_bytes(cl.bytes_freed()); 4509 4510 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4511 cl.humongous_objects_reclaimed()); 4512 } 4513 4514 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4515 public: 4516 virtual bool do_heap_region(HeapRegion* r) { 4517 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4518 G1CollectedHeap::heap()->clear_region_attr(r); 4519 r->clear_young_index_in_cset(); 4520 return false; 4521 } 4522 }; 4523 4524 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4525 G1AbandonCollectionSetClosure cl; 4526 collection_set_iterate_all(&cl); 4527 4528 collection_set->clear(); 4529 collection_set->stop_incremental_building(); 4530 } 4531 4532 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4533 return _allocator->is_retained_old_region(hr); 4534 } 4535 4536 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4537 _eden.add(hr); 4538 _policy->set_region_eden(hr); 4539 } 4540 4541 #ifdef ASSERT 4542 4543 class NoYoungRegionsClosure: public HeapRegionClosure { 4544 private: 4545 bool _success; 4546 public: 4547 NoYoungRegionsClosure() : _success(true) { } 4548 bool do_heap_region(HeapRegion* r) { 4549 if (r->is_young()) { 4550 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4551 p2i(r->bottom()), p2i(r->end())); 4552 _success = false; 4553 } 4554 return false; 4555 } 4556 bool success() { return _success; } 4557 }; 4558 4559 bool G1CollectedHeap::check_young_list_empty() { 4560 bool ret = (young_regions_count() == 0); 4561 4562 NoYoungRegionsClosure closure; 4563 heap_region_iterate(&closure); 4564 ret = ret && closure.success(); 4565 4566 return ret; 4567 } 4568 4569 #endif // ASSERT 4570 4571 class TearDownRegionSetsClosure : public HeapRegionClosure { 4572 HeapRegionSet *_old_set; 4573 4574 public: 4575 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4576 4577 bool do_heap_region(HeapRegion* r) { 4578 if (r->is_old()) { 4579 _old_set->remove(r); 4580 } else if(r->is_young()) { 4581 r->uninstall_surv_rate_group(); 4582 } else { 4583 // We ignore free regions, we'll empty the free list afterwards. 4584 // We ignore humongous and archive regions, we're not tearing down these 4585 // sets. 4586 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4587 "it cannot be another type"); 4588 } 4589 return false; 4590 } 4591 4592 ~TearDownRegionSetsClosure() { 4593 assert(_old_set->is_empty(), "post-condition"); 4594 } 4595 }; 4596 4597 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4598 assert_at_safepoint_on_vm_thread(); 4599 4600 if (!free_list_only) { 4601 TearDownRegionSetsClosure cl(&_old_set); 4602 heap_region_iterate(&cl); 4603 4604 // Note that emptying the _young_list is postponed and instead done as 4605 // the first step when rebuilding the regions sets again. The reason for 4606 // this is that during a full GC string deduplication needs to know if 4607 // a collected region was young or old when the full GC was initiated. 4608 } 4609 _hrm->remove_all_free_regions(); 4610 } 4611 4612 void G1CollectedHeap::increase_used(size_t bytes) { 4613 _summary_bytes_used += bytes; 4614 } 4615 4616 void G1CollectedHeap::decrease_used(size_t bytes) { 4617 assert(_summary_bytes_used >= bytes, 4618 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4619 _summary_bytes_used, bytes); 4620 _summary_bytes_used -= bytes; 4621 } 4622 4623 void G1CollectedHeap::set_used(size_t bytes) { 4624 _summary_bytes_used = bytes; 4625 } 4626 4627 class RebuildRegionSetsClosure : public HeapRegionClosure { 4628 private: 4629 bool _free_list_only; 4630 4631 HeapRegionSet* _old_set; 4632 HeapRegionManager* _hrm; 4633 4634 size_t _total_used; 4635 4636 public: 4637 RebuildRegionSetsClosure(bool free_list_only, 4638 HeapRegionSet* old_set, 4639 HeapRegionManager* hrm) : 4640 _free_list_only(free_list_only), 4641 _old_set(old_set), _hrm(hrm), _total_used(0) { 4642 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4643 if (!free_list_only) { 4644 assert(_old_set->is_empty(), "pre-condition"); 4645 } 4646 } 4647 4648 bool do_heap_region(HeapRegion* r) { 4649 if (r->is_empty()) { 4650 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4651 // Add free regions to the free list 4652 r->set_free(); 4653 _hrm->insert_into_free_list(r); 4654 } else if (!_free_list_only) { 4655 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4656 4657 if (r->is_archive() || r->is_humongous()) { 4658 // We ignore archive and humongous regions. We left these sets unchanged. 4659 } else { 4660 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4661 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4662 r->move_to_old(); 4663 _old_set->add(r); 4664 } 4665 _total_used += r->used(); 4666 } 4667 4668 return false; 4669 } 4670 4671 size_t total_used() { 4672 return _total_used; 4673 } 4674 }; 4675 4676 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4677 assert_at_safepoint_on_vm_thread(); 4678 4679 if (!free_list_only) { 4680 _eden.clear(); 4681 _survivor.clear(); 4682 } 4683 4684 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4685 heap_region_iterate(&cl); 4686 4687 if (!free_list_only) { 4688 set_used(cl.total_used()); 4689 if (_archive_allocator != NULL) { 4690 _archive_allocator->clear_used(); 4691 } 4692 } 4693 assert_used_and_recalculate_used_equal(this); 4694 } 4695 4696 // Methods for the mutator alloc region 4697 4698 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4699 bool force, 4700 uint node_index) { 4701 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4702 bool should_allocate = policy()->should_allocate_mutator_region(); 4703 if (force || should_allocate) { 4704 HeapRegion* new_alloc_region = new_region(word_size, 4705 HeapRegionType::Eden, 4706 false /* do_expand */, 4707 node_index); 4708 if (new_alloc_region != NULL) { 4709 set_region_short_lived_locked(new_alloc_region); 4710 _hr_printer.alloc(new_alloc_region, !should_allocate); 4711 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4712 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4713 return new_alloc_region; 4714 } 4715 } 4716 return NULL; 4717 } 4718 4719 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4720 size_t allocated_bytes) { 4721 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4722 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4723 4724 collection_set()->add_eden_region(alloc_region); 4725 increase_used(allocated_bytes); 4726 _eden.add_used_bytes(allocated_bytes); 4727 _hr_printer.retire(alloc_region); 4728 4729 // We update the eden sizes here, when the region is retired, 4730 // instead of when it's allocated, since this is the point that its 4731 // used space has been recorded in _summary_bytes_used. 4732 g1mm()->update_eden_size(); 4733 } 4734 4735 // Methods for the GC alloc regions 4736 4737 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4738 if (dest.is_old()) { 4739 return true; 4740 } else { 4741 return survivor_regions_count() < policy()->max_survivor_regions(); 4742 } 4743 } 4744 4745 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4746 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4747 4748 if (!has_more_regions(dest)) { 4749 return NULL; 4750 } 4751 4752 HeapRegionType type; 4753 if (dest.is_young()) { 4754 type = HeapRegionType::Survivor; 4755 } else { 4756 type = HeapRegionType::Old; 4757 } 4758 4759 HeapRegion* new_alloc_region = new_region(word_size, 4760 type, 4761 true /* do_expand */, 4762 node_index); 4763 4764 if (new_alloc_region != NULL) { 4765 if (type.is_survivor()) { 4766 new_alloc_region->set_survivor(); 4767 _survivor.add(new_alloc_region); 4768 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4769 } else { 4770 new_alloc_region->set_old(); 4771 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4772 } 4773 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4774 register_region_with_region_attr(new_alloc_region); 4775 _hr_printer.alloc(new_alloc_region); 4776 return new_alloc_region; 4777 } 4778 return NULL; 4779 } 4780 4781 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4782 size_t allocated_bytes, 4783 G1HeapRegionAttr dest) { 4784 _bytes_used_during_gc += allocated_bytes; 4785 if (dest.is_old()) { 4786 old_set_add(alloc_region); 4787 } else { 4788 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4789 _survivor.add_used_bytes(allocated_bytes); 4790 } 4791 4792 bool const during_im = collector_state()->in_concurrent_start_gc(); 4793 if (during_im && allocated_bytes > 0) { 4794 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4795 } 4796 _hr_printer.retire(alloc_region); 4797 } 4798 4799 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4800 bool expanded = false; 4801 uint index = _hrm->find_highest_free(&expanded); 4802 4803 if (index != G1_NO_HRM_INDEX) { 4804 if (expanded) { 4805 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4806 HeapRegion::GrainWords * HeapWordSize); 4807 } 4808 return _hrm->allocate_free_regions_starting_at(index, 1); 4809 } 4810 return NULL; 4811 } 4812 4813 // Optimized nmethod scanning 4814 4815 class RegisterNMethodOopClosure: public OopClosure { 4816 G1CollectedHeap* _g1h; 4817 nmethod* _nm; 4818 4819 template <class T> void do_oop_work(T* p) { 4820 T heap_oop = RawAccess<>::oop_load(p); 4821 if (!CompressedOops::is_null(heap_oop)) { 4822 oop obj = CompressedOops::decode_not_null(heap_oop); 4823 HeapRegion* hr = _g1h->heap_region_containing(obj); 4824 assert(!hr->is_continues_humongous(), 4825 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4826 " starting at " HR_FORMAT, 4827 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4828 4829 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4830 hr->add_strong_code_root_locked(_nm); 4831 } 4832 } 4833 4834 public: 4835 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4836 _g1h(g1h), _nm(nm) {} 4837 4838 void do_oop(oop* p) { do_oop_work(p); } 4839 void do_oop(narrowOop* p) { do_oop_work(p); } 4840 }; 4841 4842 class UnregisterNMethodOopClosure: public OopClosure { 4843 G1CollectedHeap* _g1h; 4844 nmethod* _nm; 4845 4846 template <class T> void do_oop_work(T* p) { 4847 T heap_oop = RawAccess<>::oop_load(p); 4848 if (!CompressedOops::is_null(heap_oop)) { 4849 oop obj = CompressedOops::decode_not_null(heap_oop); 4850 HeapRegion* hr = _g1h->heap_region_containing(obj); 4851 assert(!hr->is_continues_humongous(), 4852 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4853 " starting at " HR_FORMAT, 4854 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4855 4856 hr->remove_strong_code_root(_nm); 4857 } 4858 } 4859 4860 public: 4861 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4862 _g1h(g1h), _nm(nm) {} 4863 4864 void do_oop(oop* p) { do_oop_work(p); } 4865 void do_oop(narrowOop* p) { do_oop_work(p); } 4866 }; 4867 4868 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4869 guarantee(nm != NULL, "sanity"); 4870 RegisterNMethodOopClosure reg_cl(this, nm); 4871 nm->oops_do(®_cl); 4872 } 4873 4874 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4875 guarantee(nm != NULL, "sanity"); 4876 UnregisterNMethodOopClosure reg_cl(this, nm); 4877 nm->oops_do(®_cl, true); 4878 } 4879 4880 void G1CollectedHeap::purge_code_root_memory() { 4881 double purge_start = os::elapsedTime(); 4882 G1CodeRootSet::purge(); 4883 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4884 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4885 } 4886 4887 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4888 G1CollectedHeap* _g1h; 4889 4890 public: 4891 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4892 _g1h(g1h) {} 4893 4894 void do_code_blob(CodeBlob* cb) { 4895 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4896 if (nm == NULL) { 4897 return; 4898 } 4899 4900 _g1h->register_nmethod(nm); 4901 } 4902 }; 4903 4904 void G1CollectedHeap::rebuild_strong_code_roots() { 4905 RebuildStrongCodeRootClosure blob_cl(this); 4906 CodeCache::blobs_do(&blob_cl); 4907 } 4908 4909 void G1CollectedHeap::initialize_serviceability() { 4910 _g1mm->initialize_serviceability(); 4911 } 4912 4913 MemoryUsage G1CollectedHeap::memory_usage() { 4914 return _g1mm->memory_usage(); 4915 } 4916 4917 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4918 return _g1mm->memory_managers(); 4919 } 4920 4921 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4922 return _g1mm->memory_pools(); 4923 } 4924 4925 class G1ParallelObjectIterator : public ParallelObjectIterator { 4926 private: 4927 G1CollectedHeap* _heap; 4928 HeapRegionClaimer _claimer; 4929 4930 public: 4931 G1ParallelObjectIterator(uint thread_num) : 4932 _heap(G1CollectedHeap::heap()), 4933 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {} 4934 4935 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 4936 _heap->object_iterate_parallel(cl, worker_id, &_claimer); 4937 } 4938 }; 4939 4940 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) { 4941 return new G1ParallelObjectIterator(thread_num); 4942 } 4943 4944 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) { 4945 IterateObjectClosureRegionClosure blk(cl); 4946 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id); 4947 }