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/resourceArea.hpp" 93 #include "memory/universe.hpp" 94 #include "oops/access.inline.hpp" 95 #include "oops/compressedOops.inline.hpp" 96 #include "oops/oop.inline.hpp" 97 #include "runtime/atomic.hpp" 98 #include "runtime/flags/flagSetting.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/bitMap.inline.hpp" 106 #include "utilities/globalDefinitions.hpp" 107 #include "utilities/stack.inline.hpp" 108 109 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 110 111 // INVARIANTS/NOTES 112 // 113 // All allocation activity covered by the G1CollectedHeap interface is 114 // serialized by acquiring the HeapLock. This happens in mem_allocate 115 // and allocate_new_tlab, which are the "entry" points to the 116 // allocation code from the rest of the JVM. (Note that this does not 117 // apply to TLAB allocation, which is not part of this interface: it 118 // is done by clients of this interface.) 119 120 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 121 private: 122 size_t _num_dirtied; 123 G1CollectedHeap* _g1h; 124 G1CardTable* _g1_ct; 125 126 HeapRegion* region_for_card(CardValue* card_ptr) const { 127 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 128 } 129 130 bool will_become_free(HeapRegion* hr) const { 131 // A region will be freed by free_collection_set if the region is in the 132 // collection set and has not had an evacuation failure. 133 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 134 } 135 136 public: 137 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 138 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 139 140 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 141 HeapRegion* hr = region_for_card(card_ptr); 142 143 // Should only dirty cards in regions that won't be freed. 144 if (!will_become_free(hr)) { 145 *card_ptr = G1CardTable::dirty_card_val(); 146 _num_dirtied++; 147 } 148 } 149 150 size_t num_dirtied() const { return _num_dirtied; } 151 }; 152 153 154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 155 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 156 } 157 158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 159 // The from card cache is not the memory that is actually committed. So we cannot 160 // take advantage of the zero_filled parameter. 161 reset_from_card_cache(start_idx, num_regions); 162 } 163 164 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 165 Ticks start = Ticks::now(); 166 workers()->run_task(task, workers()->active_workers()); 167 return Ticks::now() - start; 168 } 169 170 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 171 MemRegion mr) { 172 return new HeapRegion(hrs_index, bot(), mr); 173 } 174 175 // Private methods. 176 177 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 178 HeapRegionType type, 179 bool do_expand, 180 uint node_index) { 181 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 182 "the only time we use this to allocate a humongous region is " 183 "when we are allocating a single humongous region"); 184 185 HeapRegion* res = _hrm->allocate_free_region(type, node_index); 186 187 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 188 // Currently, only attempts to allocate GC alloc regions set 189 // do_expand to true. So, we should only reach here during a 190 // safepoint. If this assumption changes we might have to 191 // reconsider the use of _expand_heap_after_alloc_failure. 192 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 193 194 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 195 word_size * HeapWordSize); 196 197 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 198 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 199 word_size * HeapWordSize); 200 if (expand_single_region(node_index)) { 201 // Given that expand_single_region() succeeded in expanding the heap, and we 202 // always expand the heap by an amount aligned to the heap 203 // region size, the free list should in theory not be empty. 204 // In either case allocate_free_region() will check for NULL. 205 res = _hrm->allocate_free_region(type, node_index); 206 } else { 207 _expand_heap_after_alloc_failure = false; 208 } 209 } 210 return res; 211 } 212 213 HeapWord* 214 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 215 uint num_regions, 216 size_t word_size) { 217 assert(first_hr != NULL, "pre-condition"); 218 assert(is_humongous(word_size), "word_size should be humongous"); 219 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 220 221 // Index of last region in the series. 222 uint first = first_hr->hrm_index(); 223 uint last = first + num_regions - 1; 224 225 // We need to initialize the region(s) we just discovered. This is 226 // a bit tricky given that it can happen concurrently with 227 // refinement threads refining cards on these regions and 228 // potentially wanting to refine the BOT as they are scanning 229 // those cards (this can happen shortly after a cleanup; see CR 230 // 6991377). So we have to set up the region(s) carefully and in 231 // a specific order. 232 233 // The word size sum of all the regions we will allocate. 234 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 235 assert(word_size <= word_size_sum, "sanity"); 236 237 // The passed in hr will be the "starts humongous" region. The header 238 // of the new object will be placed at the bottom of this region. 239 HeapWord* new_obj = first_hr->bottom(); 240 // This will be the new top of the new object. 241 HeapWord* obj_top = new_obj + word_size; 242 243 // First, we need to zero the header of the space that we will be 244 // allocating. When we update top further down, some refinement 245 // threads might try to scan the region. By zeroing the header we 246 // ensure that any thread that will try to scan the region will 247 // come across the zero klass word and bail out. 248 // 249 // NOTE: It would not have been correct to have used 250 // CollectedHeap::fill_with_object() and make the space look like 251 // an int array. The thread that is doing the allocation will 252 // later update the object header to a potentially different array 253 // type and, for a very short period of time, the klass and length 254 // fields will be inconsistent. This could cause a refinement 255 // thread to calculate the object size incorrectly. 256 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 257 258 // Next, pad out the unused tail of the last region with filler 259 // objects, for improved usage accounting. 260 // How many words we use for filler objects. 261 size_t word_fill_size = word_size_sum - word_size; 262 263 // How many words memory we "waste" which cannot hold a filler object. 264 size_t words_not_fillable = 0; 265 266 if (word_fill_size >= min_fill_size()) { 267 fill_with_objects(obj_top, word_fill_size); 268 } else if (word_fill_size > 0) { 269 // We have space to fill, but we cannot fit an object there. 270 words_not_fillable = word_fill_size; 271 word_fill_size = 0; 272 } 273 274 // We will set up the first region as "starts humongous". This 275 // will also update the BOT covering all the regions to reflect 276 // that there is a single object that starts at the bottom of the 277 // first region. 278 first_hr->set_starts_humongous(obj_top, word_fill_size); 279 _policy->remset_tracker()->update_at_allocate(first_hr); 280 // Then, if there are any, we will set up the "continues 281 // humongous" regions. 282 HeapRegion* hr = NULL; 283 for (uint i = first + 1; i <= last; ++i) { 284 hr = region_at(i); 285 hr->set_continues_humongous(first_hr); 286 _policy->remset_tracker()->update_at_allocate(hr); 287 } 288 289 // Up to this point no concurrent thread would have been able to 290 // do any scanning on any region in this series. All the top 291 // fields still point to bottom, so the intersection between 292 // [bottom,top] and [card_start,card_end] will be empty. Before we 293 // update the top fields, we'll do a storestore to make sure that 294 // no thread sees the update to top before the zeroing of the 295 // object header and the BOT initialization. 296 OrderAccess::storestore(); 297 298 // Now, we will update the top fields of the "continues humongous" 299 // regions except the last one. 300 for (uint i = first; i < last; ++i) { 301 hr = region_at(i); 302 hr->set_top(hr->end()); 303 } 304 305 hr = region_at(last); 306 // If we cannot fit a filler object, we must set top to the end 307 // of the humongous object, otherwise we cannot iterate the heap 308 // and the BOT will not be complete. 309 hr->set_top(hr->end() - words_not_fillable); 310 311 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 312 "obj_top should be in last region"); 313 314 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 315 316 assert(words_not_fillable == 0 || 317 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 318 "Miscalculation in humongous allocation"); 319 320 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 321 322 for (uint i = first; i <= last; ++i) { 323 hr = region_at(i); 324 _humongous_set.add(hr); 325 _hr_printer.alloc(hr); 326 } 327 328 return new_obj; 329 } 330 331 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 332 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 333 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 334 } 335 336 // If could fit into free regions w/o expansion, try. 337 // Otherwise, if can expand, do so. 338 // Otherwise, if using ex regions might help, try with ex given back. 339 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 340 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 341 342 _verifier->verify_region_sets_optional(); 343 344 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 345 346 // Policy: First try to allocate a humongous object in the free list. 347 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions); 348 if (humongous_start == NULL) { 349 // Policy: We could not find enough regions for the humongous object in the 350 // free list. Look through the heap to find a mix of free and uncommitted regions. 351 // If so, expand the heap and allocate the humongous object. 352 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions); 353 if (humongous_start != NULL) { 354 // We managed to find a region by expanding the heap. 355 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B", 356 word_size * HeapWordSize); 357 policy()->record_new_heap_size(num_regions()); 358 } else { 359 // Policy: Potentially trigger a defragmentation GC. 360 } 361 } 362 363 HeapWord* result = NULL; 364 if (humongous_start != NULL) { 365 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size); 366 assert(result != NULL, "it should always return a valid result"); 367 368 // A successful humongous object allocation changes the used space 369 // information of the old generation so we need to recalculate the 370 // sizes and update the jstat counters here. 371 g1mm()->update_sizes(); 372 } 373 374 _verifier->verify_region_sets_optional(); 375 376 return result; 377 } 378 379 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 380 size_t requested_size, 381 size_t* actual_size) { 382 assert_heap_not_locked_and_not_at_safepoint(); 383 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 384 385 return attempt_allocation(min_size, requested_size, actual_size); 386 } 387 388 HeapWord* 389 G1CollectedHeap::mem_allocate(size_t word_size, 390 bool* gc_overhead_limit_was_exceeded) { 391 assert_heap_not_locked_and_not_at_safepoint(); 392 393 if (is_humongous(word_size)) { 394 return attempt_allocation_humongous(word_size); 395 } 396 size_t dummy = 0; 397 return attempt_allocation(word_size, word_size, &dummy); 398 } 399 400 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 401 ResourceMark rm; // For retrieving the thread names in log messages. 402 403 // Make sure you read the note in attempt_allocation_humongous(). 404 405 assert_heap_not_locked_and_not_at_safepoint(); 406 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 407 "be called for humongous allocation requests"); 408 409 // We should only get here after the first-level allocation attempt 410 // (attempt_allocation()) failed to allocate. 411 412 // We will loop until a) we manage to successfully perform the 413 // allocation or b) we successfully schedule a collection which 414 // fails to perform the allocation. b) is the only case when we'll 415 // return NULL. 416 HeapWord* result = NULL; 417 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 418 bool should_try_gc; 419 uint gc_count_before; 420 421 { 422 MutexLocker x(Heap_lock); 423 result = _allocator->attempt_allocation_locked(word_size); 424 if (result != NULL) { 425 return result; 426 } 427 428 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 429 // This is different to when only GCLocker::needs_gc() is set: try to avoid 430 // waiting because the GCLocker is active to not wait too long. 431 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 432 // No need for an ergo message here, can_expand_young_list() does this when 433 // it returns true. 434 result = _allocator->attempt_allocation_force(word_size); 435 if (result != NULL) { 436 return result; 437 } 438 } 439 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 440 // the GCLocker initiated GC has been performed and then retry. This includes 441 // the case when the GC Locker is not active but has not been performed. 442 should_try_gc = !GCLocker::needs_gc(); 443 // Read the GC count while still holding the Heap_lock. 444 gc_count_before = total_collections(); 445 } 446 447 if (should_try_gc) { 448 bool succeeded; 449 result = do_collection_pause(word_size, gc_count_before, &succeeded, 450 GCCause::_g1_inc_collection_pause); 451 if (result != NULL) { 452 assert(succeeded, "only way to get back a non-NULL result"); 453 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 454 Thread::current()->name(), p2i(result)); 455 return result; 456 } 457 458 if (succeeded) { 459 // We successfully scheduled a collection which failed to allocate. No 460 // point in trying to allocate further. We'll just return NULL. 461 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 462 SIZE_FORMAT " words", Thread::current()->name(), word_size); 463 return NULL; 464 } 465 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 466 Thread::current()->name(), word_size); 467 } else { 468 // Failed to schedule a collection. 469 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 470 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 471 SIZE_FORMAT " words", Thread::current()->name(), word_size); 472 return NULL; 473 } 474 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 475 // The GCLocker is either active or the GCLocker initiated 476 // GC has not yet been performed. Stall until it is and 477 // then retry the allocation. 478 GCLocker::stall_until_clear(); 479 gclocker_retry_count += 1; 480 } 481 482 // We can reach here if we were unsuccessful in scheduling a 483 // collection (because another thread beat us to it) or if we were 484 // stalled due to the GC locker. In either can we should retry the 485 // allocation attempt in case another thread successfully 486 // performed a collection and reclaimed enough space. We do the 487 // first attempt (without holding the Heap_lock) here and the 488 // follow-on attempt will be at the start of the next loop 489 // iteration (after taking the Heap_lock). 490 size_t dummy = 0; 491 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 492 if (result != NULL) { 493 return result; 494 } 495 496 // Give a warning if we seem to be looping forever. 497 if ((QueuedAllocationWarningCount > 0) && 498 (try_count % QueuedAllocationWarningCount == 0)) { 499 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 500 Thread::current()->name(), try_count, word_size); 501 } 502 } 503 504 ShouldNotReachHere(); 505 return NULL; 506 } 507 508 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 509 assert_at_safepoint_on_vm_thread(); 510 if (_archive_allocator == NULL) { 511 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 512 } 513 } 514 515 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 516 // Allocations in archive regions cannot be of a size that would be considered 517 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 518 // may be different at archive-restore time. 519 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 520 } 521 522 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 523 assert_at_safepoint_on_vm_thread(); 524 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 525 if (is_archive_alloc_too_large(word_size)) { 526 return NULL; 527 } 528 return _archive_allocator->archive_mem_allocate(word_size); 529 } 530 531 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 532 size_t end_alignment_in_bytes) { 533 assert_at_safepoint_on_vm_thread(); 534 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 535 536 // Call complete_archive to do the real work, filling in the MemRegion 537 // array with the archive regions. 538 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 539 delete _archive_allocator; 540 _archive_allocator = NULL; 541 } 542 543 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 544 assert(ranges != NULL, "MemRegion array NULL"); 545 assert(count != 0, "No MemRegions provided"); 546 MemRegion reserved = _hrm->reserved(); 547 for (size_t i = 0; i < count; i++) { 548 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 549 return false; 550 } 551 } 552 return true; 553 } 554 555 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 556 size_t count, 557 bool open) { 558 assert(!is_init_completed(), "Expect to be called at JVM init time"); 559 assert(ranges != NULL, "MemRegion array NULL"); 560 assert(count != 0, "No MemRegions provided"); 561 MutexLocker x(Heap_lock); 562 563 MemRegion reserved = _hrm->reserved(); 564 HeapWord* prev_last_addr = NULL; 565 HeapRegion* prev_last_region = NULL; 566 567 // Temporarily disable pretouching of heap pages. This interface is used 568 // when mmap'ing archived heap data in, so pre-touching is wasted. 569 FlagSetting fs(AlwaysPreTouch, false); 570 571 // Enable archive object checking used by G1MarkSweep. We have to let it know 572 // about each archive range, so that objects in those ranges aren't marked. 573 G1ArchiveAllocator::enable_archive_object_check(); 574 575 // For each specified MemRegion range, allocate the corresponding G1 576 // regions and mark them as archive regions. We expect the ranges 577 // in ascending starting address order, without overlap. 578 for (size_t i = 0; i < count; i++) { 579 MemRegion curr_range = ranges[i]; 580 HeapWord* start_address = curr_range.start(); 581 size_t word_size = curr_range.word_size(); 582 HeapWord* last_address = curr_range.last(); 583 size_t commits = 0; 584 585 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 586 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 587 p2i(start_address), p2i(last_address)); 588 guarantee(start_address > prev_last_addr, 589 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 590 p2i(start_address), p2i(prev_last_addr)); 591 prev_last_addr = last_address; 592 593 // Check for ranges that start in the same G1 region in which the previous 594 // range ended, and adjust the start address so we don't try to allocate 595 // the same region again. If the current range is entirely within that 596 // region, skip it, just adjusting the recorded top. 597 HeapRegion* start_region = _hrm->addr_to_region(start_address); 598 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 599 start_address = start_region->end(); 600 if (start_address > last_address) { 601 increase_used(word_size * HeapWordSize); 602 start_region->set_top(last_address + 1); 603 continue; 604 } 605 start_region->set_top(start_address); 606 curr_range = MemRegion(start_address, last_address + 1); 607 start_region = _hrm->addr_to_region(start_address); 608 } 609 610 // Perform the actual region allocation, exiting if it fails. 611 // Then note how much new space we have allocated. 612 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 613 return false; 614 } 615 increase_used(word_size * HeapWordSize); 616 if (commits != 0) { 617 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 618 HeapRegion::GrainWords * HeapWordSize * commits); 619 620 } 621 622 // Mark each G1 region touched by the range as archive, add it to 623 // the old set, and set top. 624 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 625 HeapRegion* last_region = _hrm->addr_to_region(last_address); 626 prev_last_region = last_region; 627 628 while (curr_region != NULL) { 629 assert(curr_region->is_empty() && !curr_region->is_pinned(), 630 "Region already in use (index %u)", curr_region->hrm_index()); 631 if (open) { 632 curr_region->set_open_archive(); 633 } else { 634 curr_region->set_closed_archive(); 635 } 636 _hr_printer.alloc(curr_region); 637 _archive_set.add(curr_region); 638 HeapWord* top; 639 HeapRegion* next_region; 640 if (curr_region != last_region) { 641 top = curr_region->end(); 642 next_region = _hrm->next_region_in_heap(curr_region); 643 } else { 644 top = last_address + 1; 645 next_region = NULL; 646 } 647 curr_region->set_top(top); 648 curr_region = next_region; 649 } 650 651 // Notify mark-sweep of the archive 652 G1ArchiveAllocator::set_range_archive(curr_range, open); 653 } 654 return true; 655 } 656 657 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 658 assert(!is_init_completed(), "Expect to be called at JVM init time"); 659 assert(ranges != NULL, "MemRegion array NULL"); 660 assert(count != 0, "No MemRegions provided"); 661 MemRegion reserved = _hrm->reserved(); 662 HeapWord *prev_last_addr = NULL; 663 HeapRegion* prev_last_region = NULL; 664 665 // For each MemRegion, create filler objects, if needed, in the G1 regions 666 // that contain the address range. The address range actually within the 667 // MemRegion will not be modified. That is assumed to have been initialized 668 // elsewhere, probably via an mmap of archived heap data. 669 MutexLocker x(Heap_lock); 670 for (size_t i = 0; i < count; i++) { 671 HeapWord* start_address = ranges[i].start(); 672 HeapWord* last_address = ranges[i].last(); 673 674 assert(reserved.contains(start_address) && reserved.contains(last_address), 675 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 676 p2i(start_address), p2i(last_address)); 677 assert(start_address > prev_last_addr, 678 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 679 p2i(start_address), p2i(prev_last_addr)); 680 681 HeapRegion* start_region = _hrm->addr_to_region(start_address); 682 HeapRegion* last_region = _hrm->addr_to_region(last_address); 683 HeapWord* bottom_address = start_region->bottom(); 684 685 // Check for a range beginning in the same region in which the 686 // previous one ended. 687 if (start_region == prev_last_region) { 688 bottom_address = prev_last_addr + 1; 689 } 690 691 // Verify that the regions were all marked as archive regions by 692 // alloc_archive_regions. 693 HeapRegion* curr_region = start_region; 694 while (curr_region != NULL) { 695 guarantee(curr_region->is_archive(), 696 "Expected archive region at index %u", curr_region->hrm_index()); 697 if (curr_region != last_region) { 698 curr_region = _hrm->next_region_in_heap(curr_region); 699 } else { 700 curr_region = NULL; 701 } 702 } 703 704 prev_last_addr = last_address; 705 prev_last_region = last_region; 706 707 // Fill the memory below the allocated range with dummy object(s), 708 // if the region bottom does not match the range start, or if the previous 709 // range ended within the same G1 region, and there is a gap. 710 if (start_address != bottom_address) { 711 size_t fill_size = pointer_delta(start_address, bottom_address); 712 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 713 increase_used(fill_size * HeapWordSize); 714 } 715 } 716 } 717 718 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 719 size_t desired_word_size, 720 size_t* actual_word_size) { 721 assert_heap_not_locked_and_not_at_safepoint(); 722 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 723 "be called for humongous allocation requests"); 724 725 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 726 727 if (result == NULL) { 728 *actual_word_size = desired_word_size; 729 result = attempt_allocation_slow(desired_word_size); 730 } 731 732 assert_heap_not_locked(); 733 if (result != NULL) { 734 assert(*actual_word_size != 0, "Actual size must have been set here"); 735 dirty_young_block(result, *actual_word_size); 736 } else { 737 *actual_word_size = 0; 738 } 739 740 return result; 741 } 742 743 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 744 assert(!is_init_completed(), "Expect to be called at JVM init time"); 745 assert(ranges != NULL, "MemRegion array NULL"); 746 assert(count != 0, "No MemRegions provided"); 747 MemRegion reserved = _hrm->reserved(); 748 HeapWord* prev_last_addr = NULL; 749 HeapRegion* prev_last_region = NULL; 750 size_t size_used = 0; 751 size_t uncommitted_regions = 0; 752 753 // For each Memregion, free the G1 regions that constitute it, and 754 // notify mark-sweep that the range is no longer to be considered 'archive.' 755 MutexLocker x(Heap_lock); 756 for (size_t i = 0; i < count; i++) { 757 HeapWord* start_address = ranges[i].start(); 758 HeapWord* last_address = ranges[i].last(); 759 760 assert(reserved.contains(start_address) && reserved.contains(last_address), 761 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 762 p2i(start_address), p2i(last_address)); 763 assert(start_address > prev_last_addr, 764 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 765 p2i(start_address), p2i(prev_last_addr)); 766 size_used += ranges[i].byte_size(); 767 prev_last_addr = last_address; 768 769 HeapRegion* start_region = _hrm->addr_to_region(start_address); 770 HeapRegion* last_region = _hrm->addr_to_region(last_address); 771 772 // Check for ranges that start in the same G1 region in which the previous 773 // range ended, and adjust the start address so we don't try to free 774 // the same region again. If the current range is entirely within that 775 // region, skip it. 776 if (start_region == prev_last_region) { 777 start_address = start_region->end(); 778 if (start_address > last_address) { 779 continue; 780 } 781 start_region = _hrm->addr_to_region(start_address); 782 } 783 prev_last_region = last_region; 784 785 // After verifying that each region was marked as an archive region by 786 // alloc_archive_regions, set it free and empty and uncommit it. 787 HeapRegion* curr_region = start_region; 788 while (curr_region != NULL) { 789 guarantee(curr_region->is_archive(), 790 "Expected archive region at index %u", curr_region->hrm_index()); 791 uint curr_index = curr_region->hrm_index(); 792 _archive_set.remove(curr_region); 793 curr_region->set_free(); 794 curr_region->set_top(curr_region->bottom()); 795 if (curr_region != last_region) { 796 curr_region = _hrm->next_region_in_heap(curr_region); 797 } else { 798 curr_region = NULL; 799 } 800 _hrm->shrink_at(curr_index, 1); 801 uncommitted_regions++; 802 } 803 804 // Notify mark-sweep that this is no longer an archive range. 805 G1ArchiveAllocator::clear_range_archive(ranges[i]); 806 } 807 808 if (uncommitted_regions != 0) { 809 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 810 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 811 } 812 decrease_used(size_used); 813 } 814 815 oop G1CollectedHeap::materialize_archived_object(oop obj) { 816 assert(obj != NULL, "archived obj is NULL"); 817 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 818 819 // Loading an archived object makes it strongly reachable. If it is 820 // loaded during concurrent marking, it must be enqueued to the SATB 821 // queue, shading the previously white object gray. 822 G1BarrierSet::enqueue(obj); 823 824 return obj; 825 } 826 827 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 828 ResourceMark rm; // For retrieving the thread names in log messages. 829 830 // The structure of this method has a lot of similarities to 831 // attempt_allocation_slow(). The reason these two were not merged 832 // into a single one is that such a method would require several "if 833 // allocation is not humongous do this, otherwise do that" 834 // conditional paths which would obscure its flow. In fact, an early 835 // version of this code did use a unified method which was harder to 836 // follow and, as a result, it had subtle bugs that were hard to 837 // track down. So keeping these two methods separate allows each to 838 // be more readable. It will be good to keep these two in sync as 839 // much as possible. 840 841 assert_heap_not_locked_and_not_at_safepoint(); 842 assert(is_humongous(word_size), "attempt_allocation_humongous() " 843 "should only be called for humongous allocations"); 844 845 // Humongous objects can exhaust the heap quickly, so we should check if we 846 // need to start a marking cycle at each humongous object allocation. We do 847 // the check before we do the actual allocation. The reason for doing it 848 // before the allocation is that we avoid having to keep track of the newly 849 // allocated memory while we do a GC. 850 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 851 word_size)) { 852 collect(GCCause::_g1_humongous_allocation); 853 } 854 855 // We will loop until a) we manage to successfully perform the 856 // allocation or b) we successfully schedule a collection which 857 // fails to perform the allocation. b) is the only case when we'll 858 // return NULL. 859 HeapWord* result = NULL; 860 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 861 bool should_try_gc; 862 uint gc_count_before; 863 864 865 { 866 MutexLocker x(Heap_lock); 867 868 // Given that humongous objects are not allocated in young 869 // regions, we'll first try to do the allocation without doing a 870 // collection hoping that there's enough space in the heap. 871 result = humongous_obj_allocate(word_size); 872 if (result != NULL) { 873 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 874 policy()->old_gen_alloc_tracker()-> 875 add_allocated_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 876 return result; 877 } 878 879 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 880 // the GCLocker initiated GC has been performed and then retry. This includes 881 // the case when the GC Locker is not active but has not been performed. 882 should_try_gc = !GCLocker::needs_gc(); 883 // Read the GC count while still holding the Heap_lock. 884 gc_count_before = total_collections(); 885 } 886 887 if (should_try_gc) { 888 bool succeeded; 889 result = do_collection_pause(word_size, gc_count_before, &succeeded, 890 GCCause::_g1_humongous_allocation); 891 if (result != NULL) { 892 assert(succeeded, "only way to get back a non-NULL result"); 893 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 894 Thread::current()->name(), p2i(result)); 895 return result; 896 } 897 898 if (succeeded) { 899 // We successfully scheduled a collection which failed to allocate. No 900 // point in trying to allocate further. We'll just return NULL. 901 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 902 SIZE_FORMAT " words", Thread::current()->name(), word_size); 903 return NULL; 904 } 905 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 906 Thread::current()->name(), word_size); 907 } else { 908 // Failed to schedule a collection. 909 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 910 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 911 SIZE_FORMAT " words", Thread::current()->name(), word_size); 912 return NULL; 913 } 914 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 915 // The GCLocker is either active or the GCLocker initiated 916 // GC has not yet been performed. Stall until it is and 917 // then retry the allocation. 918 GCLocker::stall_until_clear(); 919 gclocker_retry_count += 1; 920 } 921 922 923 // We can reach here if we were unsuccessful in scheduling a 924 // collection (because another thread beat us to it) or if we were 925 // stalled due to the GC locker. In either can we should retry the 926 // allocation attempt in case another thread successfully 927 // performed a collection and reclaimed enough space. 928 // Humongous object allocation always needs a lock, so we wait for the retry 929 // in the next iteration of the loop, unlike for the regular iteration case. 930 // Give a warning if we seem to be looping forever. 931 932 if ((QueuedAllocationWarningCount > 0) && 933 (try_count % QueuedAllocationWarningCount == 0)) { 934 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 935 Thread::current()->name(), try_count, word_size); 936 } 937 } 938 939 ShouldNotReachHere(); 940 return NULL; 941 } 942 943 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 944 bool expect_null_mutator_alloc_region) { 945 assert_at_safepoint_on_vm_thread(); 946 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 947 "the current alloc region was unexpectedly found to be non-NULL"); 948 949 if (!is_humongous(word_size)) { 950 return _allocator->attempt_allocation_locked(word_size); 951 } else { 952 HeapWord* result = humongous_obj_allocate(word_size); 953 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 954 collector_state()->set_initiate_conc_mark_if_possible(true); 955 } 956 return result; 957 } 958 959 ShouldNotReachHere(); 960 } 961 962 class PostCompactionPrinterClosure: public HeapRegionClosure { 963 private: 964 G1HRPrinter* _hr_printer; 965 public: 966 bool do_heap_region(HeapRegion* hr) { 967 assert(!hr->is_young(), "not expecting to find young regions"); 968 _hr_printer->post_compaction(hr); 969 return false; 970 } 971 972 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 973 : _hr_printer(hr_printer) { } 974 }; 975 976 void G1CollectedHeap::print_hrm_post_compaction() { 977 if (_hr_printer.is_active()) { 978 PostCompactionPrinterClosure cl(hr_printer()); 979 heap_region_iterate(&cl); 980 } 981 } 982 983 void G1CollectedHeap::abort_concurrent_cycle() { 984 // If we start the compaction before the CM threads finish 985 // scanning the root regions we might trip them over as we'll 986 // be moving objects / updating references. So let's wait until 987 // they are done. By telling them to abort, they should complete 988 // early. 989 _cm->root_regions()->abort(); 990 _cm->root_regions()->wait_until_scan_finished(); 991 992 // Disable discovery and empty the discovered lists 993 // for the CM ref processor. 994 _ref_processor_cm->disable_discovery(); 995 _ref_processor_cm->abandon_partial_discovery(); 996 _ref_processor_cm->verify_no_references_recorded(); 997 998 // Abandon current iterations of concurrent marking and concurrent 999 // refinement, if any are in progress. 1000 concurrent_mark()->concurrent_cycle_abort(); 1001 } 1002 1003 void G1CollectedHeap::prepare_heap_for_full_collection() { 1004 // Make sure we'll choose a new allocation region afterwards. 1005 _allocator->release_mutator_alloc_regions(); 1006 _allocator->abandon_gc_alloc_regions(); 1007 1008 // We may have added regions to the current incremental collection 1009 // set between the last GC or pause and now. We need to clear the 1010 // incremental collection set and then start rebuilding it afresh 1011 // after this full GC. 1012 abandon_collection_set(collection_set()); 1013 1014 tear_down_region_sets(false /* free_list_only */); 1015 1016 hrm()->prepare_for_full_collection_start(); 1017 } 1018 1019 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1020 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1021 assert_used_and_recalculate_used_equal(this); 1022 _verifier->verify_region_sets_optional(); 1023 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1024 _verifier->check_bitmaps("Full GC Start"); 1025 } 1026 1027 void G1CollectedHeap::prepare_heap_for_mutators() { 1028 hrm()->prepare_for_full_collection_end(); 1029 1030 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1031 ClassLoaderDataGraph::purge(); 1032 MetaspaceUtils::verify_metrics(); 1033 1034 // Prepare heap for normal collections. 1035 assert(num_free_regions() == 0, "we should not have added any free regions"); 1036 rebuild_region_sets(false /* free_list_only */); 1037 abort_refinement(); 1038 resize_heap_if_necessary(); 1039 1040 // Rebuild the strong code root lists for each region 1041 rebuild_strong_code_roots(); 1042 1043 // Purge code root memory 1044 purge_code_root_memory(); 1045 1046 // Start a new incremental collection set for the next pause 1047 start_new_collection_set(); 1048 1049 _allocator->init_mutator_alloc_regions(); 1050 1051 // Post collection state updates. 1052 MetaspaceGC::compute_new_size(); 1053 } 1054 1055 void G1CollectedHeap::abort_refinement() { 1056 if (_hot_card_cache->use_cache()) { 1057 _hot_card_cache->reset_hot_cache(); 1058 } 1059 1060 // Discard all remembered set updates and reset refinement statistics. 1061 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1062 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1063 "DCQS should be empty"); 1064 concurrent_refine()->get_and_reset_refinement_stats(); 1065 } 1066 1067 void G1CollectedHeap::verify_after_full_collection() { 1068 _hrm->verify_optional(); 1069 _verifier->verify_region_sets_optional(); 1070 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1071 // Clear the previous marking bitmap, if needed for bitmap verification. 1072 // Note we cannot do this when we clear the next marking bitmap in 1073 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1074 // objects marked during a full GC against the previous bitmap. 1075 // But we need to clear it before calling check_bitmaps below since 1076 // the full GC has compacted objects and updated TAMS but not updated 1077 // the prev bitmap. 1078 if (G1VerifyBitmaps) { 1079 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1080 _cm->clear_prev_bitmap(workers()); 1081 } 1082 // This call implicitly verifies that the next bitmap is clear after Full GC. 1083 _verifier->check_bitmaps("Full GC End"); 1084 1085 // At this point there should be no regions in the 1086 // entire heap tagged as young. 1087 assert(check_young_list_empty(), "young list should be empty at this point"); 1088 1089 // Note: since we've just done a full GC, concurrent 1090 // marking is no longer active. Therefore we need not 1091 // re-enable reference discovery for the CM ref processor. 1092 // That will be done at the start of the next marking cycle. 1093 // We also know that the STW processor should no longer 1094 // discover any new references. 1095 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1096 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1097 _ref_processor_stw->verify_no_references_recorded(); 1098 _ref_processor_cm->verify_no_references_recorded(); 1099 } 1100 1101 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1102 // Post collection logging. 1103 // We should do this after we potentially resize the heap so 1104 // that all the COMMIT / UNCOMMIT events are generated before 1105 // the compaction events. 1106 print_hrm_post_compaction(); 1107 heap_transition->print(); 1108 print_heap_after_gc(); 1109 print_heap_regions(); 1110 } 1111 1112 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1113 bool clear_all_soft_refs) { 1114 assert_at_safepoint_on_vm_thread(); 1115 1116 if (GCLocker::check_active_before_gc()) { 1117 // Full GC was not completed. 1118 return false; 1119 } 1120 1121 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1122 soft_ref_policy()->should_clear_all_soft_refs(); 1123 1124 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1125 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1126 1127 collector.prepare_collection(); 1128 collector.collect(); 1129 collector.complete_collection(); 1130 1131 // Full collection was successfully completed. 1132 return true; 1133 } 1134 1135 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1136 // Currently, there is no facility in the do_full_collection(bool) API to notify 1137 // the caller that the collection did not succeed (e.g., because it was locked 1138 // out by the GC locker). So, right now, we'll ignore the return value. 1139 bool dummy = do_full_collection(true, /* explicit_gc */ 1140 clear_all_soft_refs); 1141 } 1142 1143 void G1CollectedHeap::resize_heap_if_necessary() { 1144 assert_at_safepoint_on_vm_thread(); 1145 1146 // Capacity, free and used after the GC counted as full regions to 1147 // include the waste in the following calculations. 1148 const size_t capacity_after_gc = capacity(); 1149 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1150 1151 // This is enforced in arguments.cpp. 1152 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1153 "otherwise the code below doesn't make sense"); 1154 1155 // We don't have floating point command-line arguments 1156 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1157 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1158 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1159 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1160 1161 // We have to be careful here as these two calculations can overflow 1162 // 32-bit size_t's. 1163 double used_after_gc_d = (double) used_after_gc; 1164 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1165 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1166 1167 // Let's make sure that they are both under the max heap size, which 1168 // by default will make them fit into a size_t. 1169 double desired_capacity_upper_bound = (double) MaxHeapSize; 1170 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1171 desired_capacity_upper_bound); 1172 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1173 desired_capacity_upper_bound); 1174 1175 // We can now safely turn them into size_t's. 1176 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1177 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1178 1179 // This assert only makes sense here, before we adjust them 1180 // with respect to the min and max heap size. 1181 assert(minimum_desired_capacity <= maximum_desired_capacity, 1182 "minimum_desired_capacity = " SIZE_FORMAT ", " 1183 "maximum_desired_capacity = " SIZE_FORMAT, 1184 minimum_desired_capacity, maximum_desired_capacity); 1185 1186 // Should not be greater than the heap max size. No need to adjust 1187 // it with respect to the heap min size as it's a lower bound (i.e., 1188 // we'll try to make the capacity larger than it, not smaller). 1189 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1190 // Should not be less than the heap min size. No need to adjust it 1191 // with respect to the heap max size as it's an upper bound (i.e., 1192 // we'll try to make the capacity smaller than it, not greater). 1193 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1194 1195 if (capacity_after_gc < minimum_desired_capacity) { 1196 // Don't expand unless it's significant 1197 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1198 1199 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1200 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1201 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1202 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1203 1204 expand(expand_bytes, _workers); 1205 1206 // No expansion, now see if we want to shrink 1207 } else if (capacity_after_gc > maximum_desired_capacity) { 1208 // Capacity too large, compute shrinking size 1209 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1210 1211 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1212 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1213 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1214 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1215 1216 shrink(shrink_bytes); 1217 } 1218 } 1219 1220 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1221 bool do_gc, 1222 bool clear_all_soft_refs, 1223 bool expect_null_mutator_alloc_region, 1224 bool* gc_succeeded) { 1225 *gc_succeeded = true; 1226 // Let's attempt the allocation first. 1227 HeapWord* result = 1228 attempt_allocation_at_safepoint(word_size, 1229 expect_null_mutator_alloc_region); 1230 if (result != NULL) { 1231 return result; 1232 } 1233 1234 // In a G1 heap, we're supposed to keep allocation from failing by 1235 // incremental pauses. Therefore, at least for now, we'll favor 1236 // expansion over collection. (This might change in the future if we can 1237 // do something smarter than full collection to satisfy a failed alloc.) 1238 result = expand_and_allocate(word_size); 1239 if (result != NULL) { 1240 return result; 1241 } 1242 1243 if (do_gc) { 1244 // Expansion didn't work, we'll try to do a Full GC. 1245 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1246 clear_all_soft_refs); 1247 } 1248 1249 return NULL; 1250 } 1251 1252 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1253 bool* succeeded) { 1254 assert_at_safepoint_on_vm_thread(); 1255 1256 // Attempts to allocate followed by Full GC. 1257 HeapWord* result = 1258 satisfy_failed_allocation_helper(word_size, 1259 true, /* do_gc */ 1260 false, /* clear_all_soft_refs */ 1261 false, /* expect_null_mutator_alloc_region */ 1262 succeeded); 1263 1264 if (result != NULL || !*succeeded) { 1265 return result; 1266 } 1267 1268 // Attempts to allocate followed by Full GC that will collect all soft references. 1269 result = satisfy_failed_allocation_helper(word_size, 1270 true, /* do_gc */ 1271 true, /* clear_all_soft_refs */ 1272 true, /* expect_null_mutator_alloc_region */ 1273 succeeded); 1274 1275 if (result != NULL || !*succeeded) { 1276 return result; 1277 } 1278 1279 // Attempts to allocate, no GC 1280 result = satisfy_failed_allocation_helper(word_size, 1281 false, /* do_gc */ 1282 false, /* clear_all_soft_refs */ 1283 true, /* expect_null_mutator_alloc_region */ 1284 succeeded); 1285 1286 if (result != NULL) { 1287 return result; 1288 } 1289 1290 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1291 "Flag should have been handled and cleared prior to this point"); 1292 1293 // What else? We might try synchronous finalization later. If the total 1294 // space available is large enough for the allocation, then a more 1295 // complete compaction phase than we've tried so far might be 1296 // appropriate. 1297 return NULL; 1298 } 1299 1300 // Attempting to expand the heap sufficiently 1301 // to support an allocation of the given "word_size". If 1302 // successful, perform the allocation and return the address of the 1303 // allocated block, or else "NULL". 1304 1305 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1306 assert_at_safepoint_on_vm_thread(); 1307 1308 _verifier->verify_region_sets_optional(); 1309 1310 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1311 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1312 word_size * HeapWordSize); 1313 1314 1315 if (expand(expand_bytes, _workers)) { 1316 _hrm->verify_optional(); 1317 _verifier->verify_region_sets_optional(); 1318 return attempt_allocation_at_safepoint(word_size, 1319 false /* expect_null_mutator_alloc_region */); 1320 } 1321 return NULL; 1322 } 1323 1324 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1325 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1326 aligned_expand_bytes = align_up(aligned_expand_bytes, 1327 HeapRegion::GrainBytes); 1328 1329 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1330 expand_bytes, aligned_expand_bytes); 1331 1332 if (is_maximal_no_gc()) { 1333 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1334 return false; 1335 } 1336 1337 double expand_heap_start_time_sec = os::elapsedTime(); 1338 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1339 assert(regions_to_expand > 0, "Must expand by at least one region"); 1340 1341 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1342 if (expand_time_ms != NULL) { 1343 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1344 } 1345 1346 if (expanded_by > 0) { 1347 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1348 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1349 policy()->record_new_heap_size(num_regions()); 1350 } else { 1351 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1352 1353 // The expansion of the virtual storage space was unsuccessful. 1354 // Let's see if it was because we ran out of swap. 1355 if (G1ExitOnExpansionFailure && 1356 _hrm->available() >= regions_to_expand) { 1357 // We had head room... 1358 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1359 } 1360 } 1361 return regions_to_expand > 0; 1362 } 1363 1364 bool G1CollectedHeap::expand_single_region(uint node_index) { 1365 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1366 1367 if (expanded_by == 0) { 1368 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1369 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1370 return false; 1371 } 1372 1373 policy()->record_new_heap_size(num_regions()); 1374 return true; 1375 } 1376 1377 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1378 size_t aligned_shrink_bytes = 1379 ReservedSpace::page_align_size_down(shrink_bytes); 1380 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1381 HeapRegion::GrainBytes); 1382 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1383 1384 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1385 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1386 1387 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", 1388 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1389 if (num_regions_removed > 0) { 1390 policy()->record_new_heap_size(num_regions()); 1391 } else { 1392 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1393 } 1394 } 1395 1396 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1397 _verifier->verify_region_sets_optional(); 1398 1399 // We should only reach here at the end of a Full GC or during Remark which 1400 // means we should not not be holding to any GC alloc regions. The method 1401 // below will make sure of that and do any remaining clean up. 1402 _allocator->abandon_gc_alloc_regions(); 1403 1404 // Instead of tearing down / rebuilding the free lists here, we 1405 // could instead use the remove_all_pending() method on free_list to 1406 // remove only the ones that we need to remove. 1407 tear_down_region_sets(true /* free_list_only */); 1408 shrink_helper(shrink_bytes); 1409 rebuild_region_sets(true /* free_list_only */); 1410 1411 _hrm->verify_optional(); 1412 _verifier->verify_region_sets_optional(); 1413 } 1414 1415 class OldRegionSetChecker : public HeapRegionSetChecker { 1416 public: 1417 void check_mt_safety() { 1418 // Master Old Set MT safety protocol: 1419 // (a) If we're at a safepoint, operations on the master old set 1420 // should be invoked: 1421 // - by the VM thread (which will serialize them), or 1422 // - by the GC workers while holding the FreeList_lock, if we're 1423 // at a safepoint for an evacuation pause (this lock is taken 1424 // anyway when an GC alloc region is retired so that a new one 1425 // is allocated from the free list), or 1426 // - by the GC workers while holding the OldSets_lock, if we're at a 1427 // safepoint for a cleanup pause. 1428 // (b) If we're not at a safepoint, operations on the master old set 1429 // should be invoked while holding the Heap_lock. 1430 1431 if (SafepointSynchronize::is_at_safepoint()) { 1432 guarantee(Thread::current()->is_VM_thread() || 1433 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1434 "master old set MT safety protocol at a safepoint"); 1435 } else { 1436 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1437 } 1438 } 1439 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1440 const char* get_description() { return "Old Regions"; } 1441 }; 1442 1443 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1444 public: 1445 void check_mt_safety() { 1446 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1447 "May only change archive regions during initialization or safepoint."); 1448 } 1449 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1450 const char* get_description() { return "Archive Regions"; } 1451 }; 1452 1453 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1454 public: 1455 void check_mt_safety() { 1456 // Humongous Set MT safety protocol: 1457 // (a) If we're at a safepoint, operations on the master humongous 1458 // set should be invoked by either the VM thread (which will 1459 // serialize them) or by the GC workers while holding the 1460 // OldSets_lock. 1461 // (b) If we're not at a safepoint, operations on the master 1462 // humongous set should be invoked while holding the Heap_lock. 1463 1464 if (SafepointSynchronize::is_at_safepoint()) { 1465 guarantee(Thread::current()->is_VM_thread() || 1466 OldSets_lock->owned_by_self(), 1467 "master humongous set MT safety protocol at a safepoint"); 1468 } else { 1469 guarantee(Heap_lock->owned_by_self(), 1470 "master humongous set MT safety protocol outside a safepoint"); 1471 } 1472 } 1473 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1474 const char* get_description() { return "Humongous Regions"; } 1475 }; 1476 1477 G1CollectedHeap::G1CollectedHeap() : 1478 CollectedHeap(), 1479 _young_gen_sampling_thread(NULL), 1480 _workers(NULL), 1481 _card_table(NULL), 1482 _soft_ref_policy(), 1483 _old_set("Old Region Set", new OldRegionSetChecker()), 1484 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1485 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1486 _bot(NULL), 1487 _listener(), 1488 _numa(G1NUMA::create()), 1489 _hrm(NULL), 1490 _allocator(NULL), 1491 _verifier(NULL), 1492 _summary_bytes_used(0), 1493 _bytes_used_during_gc(0), 1494 _archive_allocator(NULL), 1495 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1496 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1497 _expand_heap_after_alloc_failure(true), 1498 _g1mm(NULL), 1499 _humongous_reclaim_candidates(), 1500 _has_humongous_reclaim_candidates(false), 1501 _hr_printer(), 1502 _collector_state(), 1503 _old_marking_cycles_started(0), 1504 _old_marking_cycles_completed(0), 1505 _eden(), 1506 _survivor(), 1507 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1508 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1509 _policy(G1Policy::create_policy(_gc_timer_stw)), 1510 _heap_sizing_policy(NULL), 1511 _collection_set(this, _policy), 1512 _hot_card_cache(NULL), 1513 _rem_set(NULL), 1514 _cm(NULL), 1515 _cm_thread(NULL), 1516 _cr(NULL), 1517 _task_queues(NULL), 1518 _evacuation_failed(false), 1519 _evacuation_failed_info_array(NULL), 1520 _preserved_marks_set(true /* in_c_heap */), 1521 #ifndef PRODUCT 1522 _evacuation_failure_alot_for_current_gc(false), 1523 _evacuation_failure_alot_gc_number(0), 1524 _evacuation_failure_alot_count(0), 1525 #endif 1526 _ref_processor_stw(NULL), 1527 _is_alive_closure_stw(this), 1528 _is_subject_to_discovery_stw(this), 1529 _ref_processor_cm(NULL), 1530 _is_alive_closure_cm(this), 1531 _is_subject_to_discovery_cm(this), 1532 _region_attr() { 1533 1534 _verifier = new G1HeapVerifier(this); 1535 1536 _allocator = new G1Allocator(this); 1537 1538 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1539 1540 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1541 1542 // Override the default _filler_array_max_size so that no humongous filler 1543 // objects are created. 1544 _filler_array_max_size = _humongous_object_threshold_in_words; 1545 1546 uint n_queues = ParallelGCThreads; 1547 _task_queues = new G1ScannerTasksQueueSet(n_queues); 1548 1549 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1550 1551 for (uint i = 0; i < n_queues; i++) { 1552 G1ScannerTasksQueue* q = new G1ScannerTasksQueue(); 1553 q->initialize(); 1554 _task_queues->register_queue(i, q); 1555 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1556 } 1557 1558 // Initialize the G1EvacuationFailureALot counters and flags. 1559 NOT_PRODUCT(reset_evacuation_should_fail();) 1560 _gc_tracer_stw->initialize(); 1561 1562 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1563 } 1564 1565 static size_t actual_reserved_page_size(ReservedSpace rs) { 1566 size_t page_size = os::vm_page_size(); 1567 if (UseLargePages) { 1568 // There are two ways to manage large page memory. 1569 // 1. OS supports committing large page memory. 1570 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1571 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1572 // we reserved memory without large page. 1573 if (os::can_commit_large_page_memory() || rs.special()) { 1574 // An alignment at ReservedSpace comes from preferred page size or 1575 // heap alignment, and if the alignment came from heap alignment, it could be 1576 // larger than large pages size. So need to cap with the large page size. 1577 page_size = MIN2(rs.alignment(), os::large_page_size()); 1578 } 1579 } 1580 1581 return page_size; 1582 } 1583 1584 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1585 size_t size, 1586 size_t translation_factor) { 1587 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1588 // Allocate a new reserved space, preferring to use large pages. 1589 ReservedSpace rs(size, preferred_page_size); 1590 size_t page_size = actual_reserved_page_size(rs); 1591 G1RegionToSpaceMapper* result = 1592 G1RegionToSpaceMapper::create_mapper(rs, 1593 size, 1594 page_size, 1595 HeapRegion::GrainBytes, 1596 translation_factor, 1597 mtGC); 1598 1599 os::trace_page_sizes_for_requested_size(description, 1600 size, 1601 preferred_page_size, 1602 page_size, 1603 rs.base(), 1604 rs.size()); 1605 1606 return result; 1607 } 1608 1609 jint G1CollectedHeap::initialize_concurrent_refinement() { 1610 jint ecode = JNI_OK; 1611 _cr = G1ConcurrentRefine::create(&ecode); 1612 return ecode; 1613 } 1614 1615 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1616 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1617 if (_young_gen_sampling_thread->osthread() == NULL) { 1618 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1619 return JNI_ENOMEM; 1620 } 1621 return JNI_OK; 1622 } 1623 1624 jint G1CollectedHeap::initialize() { 1625 1626 // Necessary to satisfy locking discipline assertions. 1627 1628 MutexLocker x(Heap_lock); 1629 1630 // While there are no constraints in the GC code that HeapWordSize 1631 // be any particular value, there are multiple other areas in the 1632 // system which believe this to be true (e.g. oop->object_size in some 1633 // cases incorrectly returns the size in wordSize units rather than 1634 // HeapWordSize). 1635 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1636 1637 size_t init_byte_size = InitialHeapSize; 1638 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1639 1640 // Ensure that the sizes are properly aligned. 1641 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1642 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1643 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1644 1645 // Reserve the maximum. 1646 1647 // When compressed oops are enabled, the preferred heap base 1648 // is calculated by subtracting the requested size from the 1649 // 32Gb boundary and using the result as the base address for 1650 // heap reservation. If the requested size is not aligned to 1651 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1652 // into the ReservedHeapSpace constructor) then the actual 1653 // base of the reserved heap may end up differing from the 1654 // address that was requested (i.e. the preferred heap base). 1655 // If this happens then we could end up using a non-optimal 1656 // compressed oops mode. 1657 1658 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1659 HeapAlignment); 1660 1661 initialize_reserved_region(heap_rs); 1662 1663 // Create the barrier set for the entire reserved region. 1664 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1665 ct->initialize(); 1666 G1BarrierSet* bs = new G1BarrierSet(ct); 1667 bs->initialize(); 1668 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1669 BarrierSet::set_barrier_set(bs); 1670 _card_table = ct; 1671 1672 { 1673 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1674 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1675 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1676 } 1677 1678 // Create the hot card cache. 1679 _hot_card_cache = new G1HotCardCache(this); 1680 1681 // Carve out the G1 part of the heap. 1682 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1683 size_t page_size = actual_reserved_page_size(heap_rs); 1684 G1RegionToSpaceMapper* heap_storage = 1685 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1686 g1_rs.size(), 1687 page_size, 1688 HeapRegion::GrainBytes, 1689 1, 1690 mtJavaHeap); 1691 if(heap_storage == NULL) { 1692 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1693 return JNI_ERR; 1694 } 1695 1696 os::trace_page_sizes("Heap", 1697 MinHeapSize, 1698 reserved_byte_size, 1699 page_size, 1700 heap_rs.base(), 1701 heap_rs.size()); 1702 heap_storage->set_mapping_changed_listener(&_listener); 1703 1704 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1705 G1RegionToSpaceMapper* bot_storage = 1706 create_aux_memory_mapper("Block Offset Table", 1707 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1708 G1BlockOffsetTable::heap_map_factor()); 1709 1710 G1RegionToSpaceMapper* cardtable_storage = 1711 create_aux_memory_mapper("Card Table", 1712 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1713 G1CardTable::heap_map_factor()); 1714 1715 G1RegionToSpaceMapper* card_counts_storage = 1716 create_aux_memory_mapper("Card Counts Table", 1717 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1718 G1CardCounts::heap_map_factor()); 1719 1720 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1721 G1RegionToSpaceMapper* prev_bitmap_storage = 1722 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1723 G1RegionToSpaceMapper* next_bitmap_storage = 1724 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1725 1726 _hrm = HeapRegionManager::create_manager(this); 1727 1728 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1729 _card_table->initialize(cardtable_storage); 1730 1731 // Do later initialization work for concurrent refinement. 1732 _hot_card_cache->initialize(card_counts_storage); 1733 1734 // 6843694 - ensure that the maximum region index can fit 1735 // in the remembered set structures. 1736 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1737 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1738 1739 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1740 // start within the first card. 1741 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1742 // Also create a G1 rem set. 1743 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1744 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1745 1746 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1747 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1748 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1749 "too many cards per region"); 1750 1751 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1752 1753 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1754 1755 { 1756 HeapWord* start = _hrm->reserved().start(); 1757 HeapWord* end = _hrm->reserved().end(); 1758 size_t granularity = HeapRegion::GrainBytes; 1759 1760 _region_attr.initialize(start, end, granularity); 1761 _humongous_reclaim_candidates.initialize(start, end, granularity); 1762 } 1763 1764 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1765 true /* are_GC_task_threads */, 1766 false /* are_ConcurrentGC_threads */); 1767 if (_workers == NULL) { 1768 return JNI_ENOMEM; 1769 } 1770 _workers->initialize_workers(); 1771 1772 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1773 1774 // Create the G1ConcurrentMark data structure and thread. 1775 // (Must do this late, so that "max_regions" is defined.) 1776 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1777 _cm_thread = _cm->cm_thread(); 1778 1779 // Now expand into the initial heap size. 1780 if (!expand(init_byte_size, _workers)) { 1781 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1782 return JNI_ENOMEM; 1783 } 1784 1785 // Perform any initialization actions delegated to the policy. 1786 policy()->init(this, &_collection_set); 1787 1788 jint ecode = initialize_concurrent_refinement(); 1789 if (ecode != JNI_OK) { 1790 return ecode; 1791 } 1792 1793 ecode = initialize_young_gen_sampling_thread(); 1794 if (ecode != JNI_OK) { 1795 return ecode; 1796 } 1797 1798 { 1799 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1800 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1801 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1802 } 1803 1804 // Here we allocate the dummy HeapRegion that is required by the 1805 // G1AllocRegion class. 1806 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1807 1808 // We'll re-use the same region whether the alloc region will 1809 // require BOT updates or not and, if it doesn't, then a non-young 1810 // region will complain that it cannot support allocations without 1811 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1812 dummy_region->set_eden(); 1813 // Make sure it's full. 1814 dummy_region->set_top(dummy_region->end()); 1815 G1AllocRegion::setup(this, dummy_region); 1816 1817 _allocator->init_mutator_alloc_regions(); 1818 1819 // Do create of the monitoring and management support so that 1820 // values in the heap have been properly initialized. 1821 _g1mm = new G1MonitoringSupport(this); 1822 1823 G1StringDedup::initialize(); 1824 1825 _preserved_marks_set.init(ParallelGCThreads); 1826 1827 _collection_set.initialize(max_regions()); 1828 1829 G1InitLogger::print(); 1830 1831 return JNI_OK; 1832 } 1833 1834 void G1CollectedHeap::stop() { 1835 // Stop all concurrent threads. We do this to make sure these threads 1836 // do not continue to execute and access resources (e.g. logging) 1837 // that are destroyed during shutdown. 1838 _cr->stop(); 1839 _young_gen_sampling_thread->stop(); 1840 _cm_thread->stop(); 1841 if (G1StringDedup::is_enabled()) { 1842 G1StringDedup::stop(); 1843 } 1844 } 1845 1846 void G1CollectedHeap::safepoint_synchronize_begin() { 1847 SuspendibleThreadSet::synchronize(); 1848 } 1849 1850 void G1CollectedHeap::safepoint_synchronize_end() { 1851 SuspendibleThreadSet::desynchronize(); 1852 } 1853 1854 void G1CollectedHeap::post_initialize() { 1855 CollectedHeap::post_initialize(); 1856 ref_processing_init(); 1857 } 1858 1859 void G1CollectedHeap::ref_processing_init() { 1860 // Reference processing in G1 currently works as follows: 1861 // 1862 // * There are two reference processor instances. One is 1863 // used to record and process discovered references 1864 // during concurrent marking; the other is used to 1865 // record and process references during STW pauses 1866 // (both full and incremental). 1867 // * Both ref processors need to 'span' the entire heap as 1868 // the regions in the collection set may be dotted around. 1869 // 1870 // * For the concurrent marking ref processor: 1871 // * Reference discovery is enabled at initial marking. 1872 // * Reference discovery is disabled and the discovered 1873 // references processed etc during remarking. 1874 // * Reference discovery is MT (see below). 1875 // * Reference discovery requires a barrier (see below). 1876 // * Reference processing may or may not be MT 1877 // (depending on the value of ParallelRefProcEnabled 1878 // and ParallelGCThreads). 1879 // * A full GC disables reference discovery by the CM 1880 // ref processor and abandons any entries on it's 1881 // discovered lists. 1882 // 1883 // * For the STW processor: 1884 // * Non MT discovery is enabled at the start of a full GC. 1885 // * Processing and enqueueing during a full GC is non-MT. 1886 // * During a full GC, references are processed after marking. 1887 // 1888 // * Discovery (may or may not be MT) is enabled at the start 1889 // of an incremental evacuation pause. 1890 // * References are processed near the end of a STW evacuation pause. 1891 // * For both types of GC: 1892 // * Discovery is atomic - i.e. not concurrent. 1893 // * Reference discovery will not need a barrier. 1894 1895 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1896 1897 // Concurrent Mark ref processor 1898 _ref_processor_cm = 1899 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1900 mt_processing, // mt processing 1901 ParallelGCThreads, // degree of mt processing 1902 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1903 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1904 false, // Reference discovery is not atomic 1905 &_is_alive_closure_cm, // is alive closure 1906 true); // allow changes to number of processing threads 1907 1908 // STW ref processor 1909 _ref_processor_stw = 1910 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1911 mt_processing, // mt processing 1912 ParallelGCThreads, // degree of mt processing 1913 (ParallelGCThreads > 1), // mt discovery 1914 ParallelGCThreads, // degree of mt discovery 1915 true, // Reference discovery is atomic 1916 &_is_alive_closure_stw, // is alive closure 1917 true); // allow changes to number of processing threads 1918 } 1919 1920 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1921 return &_soft_ref_policy; 1922 } 1923 1924 size_t G1CollectedHeap::capacity() const { 1925 return _hrm->length() * HeapRegion::GrainBytes; 1926 } 1927 1928 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1929 return _hrm->total_free_bytes(); 1930 } 1931 1932 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1933 _hot_card_cache->drain(cl, worker_id); 1934 } 1935 1936 // Computes the sum of the storage used by the various regions. 1937 size_t G1CollectedHeap::used() const { 1938 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1939 if (_archive_allocator != NULL) { 1940 result += _archive_allocator->used(); 1941 } 1942 return result; 1943 } 1944 1945 size_t G1CollectedHeap::used_unlocked() const { 1946 return _summary_bytes_used; 1947 } 1948 1949 class SumUsedClosure: public HeapRegionClosure { 1950 size_t _used; 1951 public: 1952 SumUsedClosure() : _used(0) {} 1953 bool do_heap_region(HeapRegion* r) { 1954 _used += r->used(); 1955 return false; 1956 } 1957 size_t result() { return _used; } 1958 }; 1959 1960 size_t G1CollectedHeap::recalculate_used() const { 1961 SumUsedClosure blk; 1962 heap_region_iterate(&blk); 1963 return blk.result(); 1964 } 1965 1966 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1967 switch (cause) { 1968 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1969 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1970 case GCCause::_wb_conc_mark: return true; 1971 default : return false; 1972 } 1973 } 1974 1975 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1976 switch (cause) { 1977 case GCCause::_g1_humongous_allocation: return true; 1978 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1979 case GCCause::_wb_breakpoint: return true; 1980 default: return is_user_requested_concurrent_full_gc(cause); 1981 } 1982 } 1983 1984 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 1985 if (policy()->force_upgrade_to_full()) { 1986 return true; 1987 } else if (should_do_concurrent_full_gc(_gc_cause)) { 1988 return false; 1989 } else if (has_regions_left_for_allocation()) { 1990 return false; 1991 } else { 1992 return true; 1993 } 1994 } 1995 1996 #ifndef PRODUCT 1997 void G1CollectedHeap::allocate_dummy_regions() { 1998 // Let's fill up most of the region 1999 size_t word_size = HeapRegion::GrainWords - 1024; 2000 // And as a result the region we'll allocate will be humongous. 2001 guarantee(is_humongous(word_size), "sanity"); 2002 2003 // _filler_array_max_size is set to humongous object threshold 2004 // but temporarily change it to use CollectedHeap::fill_with_object(). 2005 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2006 2007 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2008 // Let's use the existing mechanism for the allocation 2009 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2010 if (dummy_obj != NULL) { 2011 MemRegion mr(dummy_obj, word_size); 2012 CollectedHeap::fill_with_object(mr); 2013 } else { 2014 // If we can't allocate once, we probably cannot allocate 2015 // again. Let's get out of the loop. 2016 break; 2017 } 2018 } 2019 } 2020 #endif // !PRODUCT 2021 2022 void G1CollectedHeap::increment_old_marking_cycles_started() { 2023 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2024 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2025 "Wrong marking cycle count (started: %d, completed: %d)", 2026 _old_marking_cycles_started, _old_marking_cycles_completed); 2027 2028 _old_marking_cycles_started++; 2029 } 2030 2031 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2032 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 2033 2034 // We assume that if concurrent == true, then the caller is a 2035 // concurrent thread that was joined the Suspendible Thread 2036 // Set. If there's ever a cheap way to check this, we should add an 2037 // assert here. 2038 2039 // Given that this method is called at the end of a Full GC or of a 2040 // concurrent cycle, and those can be nested (i.e., a Full GC can 2041 // interrupt a concurrent cycle), the number of full collections 2042 // completed should be either one (in the case where there was no 2043 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2044 // behind the number of full collections started. 2045 2046 // This is the case for the inner caller, i.e. a Full GC. 2047 assert(concurrent || 2048 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2049 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2050 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2051 "is inconsistent with _old_marking_cycles_completed = %u", 2052 _old_marking_cycles_started, _old_marking_cycles_completed); 2053 2054 // This is the case for the outer caller, i.e. the concurrent cycle. 2055 assert(!concurrent || 2056 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2057 "for outer caller (concurrent cycle): " 2058 "_old_marking_cycles_started = %u " 2059 "is inconsistent with _old_marking_cycles_completed = %u", 2060 _old_marking_cycles_started, _old_marking_cycles_completed); 2061 2062 _old_marking_cycles_completed += 1; 2063 2064 // We need to clear the "in_progress" flag in the CM thread before 2065 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2066 // is set) so that if a waiter requests another System.gc() it doesn't 2067 // incorrectly see that a marking cycle is still in progress. 2068 if (concurrent) { 2069 _cm_thread->set_idle(); 2070 } 2071 2072 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 2073 // for a full GC to finish that their wait is over. 2074 ml.notify_all(); 2075 } 2076 2077 void G1CollectedHeap::collect(GCCause::Cause cause) { 2078 try_collect(cause); 2079 } 2080 2081 // Return true if (x < y) with allowance for wraparound. 2082 static bool gc_counter_less_than(uint x, uint y) { 2083 return (x - y) > (UINT_MAX/2); 2084 } 2085 2086 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 2087 // Macro so msg printing is format-checked. 2088 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 2089 do { \ 2090 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 2091 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 2092 ResourceMark rm; /* For thread name. */ \ 2093 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 2094 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 2095 Thread::current()->name(), \ 2096 GCCause::to_string(cause)); \ 2097 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 2098 } \ 2099 } while (0) 2100 2101 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 2102 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 2103 2104 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 2105 uint gc_counter, 2106 uint old_marking_started_before) { 2107 assert_heap_not_locked(); 2108 assert(should_do_concurrent_full_gc(cause), 2109 "Non-concurrent cause %s", GCCause::to_string(cause)); 2110 2111 for (uint i = 1; true; ++i) { 2112 // Try to schedule an initial-mark evacuation pause that will 2113 // start a concurrent cycle. 2114 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 2115 VM_G1TryInitiateConcMark op(gc_counter, 2116 cause, 2117 policy()->max_pause_time_ms()); 2118 VMThread::execute(&op); 2119 2120 // Request is trivially finished. 2121 if (cause == GCCause::_g1_periodic_collection) { 2122 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 2123 return op.gc_succeeded(); 2124 } 2125 2126 // If VMOp skipped initiating concurrent marking cycle because 2127 // we're terminating, then we're done. 2128 if (op.terminating()) { 2129 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 2130 return false; 2131 } 2132 2133 // Lock to get consistent set of values. 2134 uint old_marking_started_after; 2135 uint old_marking_completed_after; 2136 { 2137 MutexLocker ml(Heap_lock); 2138 // Update gc_counter for retrying VMOp if needed. Captured here to be 2139 // consistent with the values we use below for termination tests. If 2140 // a retry is needed after a possible wait, and another collection 2141 // occurs in the meantime, it will cause our retry to be skipped and 2142 // we'll recheck for termination with updated conditions from that 2143 // more recent collection. That's what we want, rather than having 2144 // our retry possibly perform an unnecessary collection. 2145 gc_counter = total_collections(); 2146 old_marking_started_after = _old_marking_cycles_started; 2147 old_marking_completed_after = _old_marking_cycles_completed; 2148 } 2149 2150 if (cause == GCCause::_wb_breakpoint) { 2151 if (op.gc_succeeded()) { 2152 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2153 return true; 2154 } 2155 // When _wb_breakpoint there can't be another cycle or deferred. 2156 assert(!op.cycle_already_in_progress(), "invariant"); 2157 assert(!op.whitebox_attached(), "invariant"); 2158 // Concurrent cycle attempt might have been cancelled by some other 2159 // collection, so retry. Unlike other cases below, we want to retry 2160 // even if cancelled by a STW full collection, because we really want 2161 // to start a concurrent cycle. 2162 if (old_marking_started_before != old_marking_started_after) { 2163 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 2164 old_marking_started_before = old_marking_started_after; 2165 } 2166 } else if (!GCCause::is_user_requested_gc(cause)) { 2167 // For an "automatic" (not user-requested) collection, we just need to 2168 // ensure that progress is made. 2169 // 2170 // Request is finished if any of 2171 // (1) the VMOp successfully performed a GC, 2172 // (2) a concurrent cycle was already in progress, 2173 // (3) whitebox is controlling concurrent cycles, 2174 // (4) a new cycle was started (by this thread or some other), or 2175 // (5) a Full GC was performed. 2176 // Cases (4) and (5) are detected together by a change to 2177 // _old_marking_cycles_started. 2178 // 2179 // Note that (1) does not imply (4). If we're still in the mixed 2180 // phase of an earlier concurrent collection, the request to make the 2181 // collection an initial-mark won't be honored. If we don't check for 2182 // both conditions we'll spin doing back-to-back collections. 2183 if (op.gc_succeeded() || 2184 op.cycle_already_in_progress() || 2185 op.whitebox_attached() || 2186 (old_marking_started_before != old_marking_started_after)) { 2187 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2188 return true; 2189 } 2190 } else { // User-requested GC. 2191 // For a user-requested collection, we want to ensure that a complete 2192 // full collection has been performed before returning, but without 2193 // waiting for more than needed. 2194 2195 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 2196 // new cycle was started. That's good, because it's not clear what we 2197 // should do otherwise. Trying again just does back to back GCs. 2198 // Can't wait for someone else to start a cycle. And returning fails 2199 // to meet the goal of ensuring a full collection was performed. 2200 assert(!op.gc_succeeded() || 2201 (old_marking_started_before != old_marking_started_after), 2202 "invariant: succeeded %s, started before %u, started after %u", 2203 BOOL_TO_STR(op.gc_succeeded()), 2204 old_marking_started_before, old_marking_started_after); 2205 2206 // Request is finished if a full collection (concurrent or stw) 2207 // was started after this request and has completed, e.g. 2208 // started_before < completed_after. 2209 if (gc_counter_less_than(old_marking_started_before, 2210 old_marking_completed_after)) { 2211 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2212 return true; 2213 } 2214 2215 if (old_marking_started_after != old_marking_completed_after) { 2216 // If there is an in-progress cycle (possibly started by us), then 2217 // wait for that cycle to complete, e.g. 2218 // while completed_now < started_after. 2219 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2220 MonitorLocker ml(G1OldGCCount_lock); 2221 while (gc_counter_less_than(_old_marking_cycles_completed, 2222 old_marking_started_after)) { 2223 ml.wait(); 2224 } 2225 // Request is finished if the collection we just waited for was 2226 // started after this request. 2227 if (old_marking_started_before != old_marking_started_after) { 2228 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2229 return true; 2230 } 2231 } 2232 2233 // If VMOp was successful then it started a new cycle that the above 2234 // wait &etc should have recognized as finishing this request. This 2235 // differs from a non-user-request, where gc_succeeded does not imply 2236 // a new cycle was started. 2237 assert(!op.gc_succeeded(), "invariant"); 2238 2239 if (op.cycle_already_in_progress()) { 2240 // If VMOp failed because a cycle was already in progress, it 2241 // is now complete. But it didn't finish this user-requested 2242 // GC, so try again. 2243 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2244 continue; 2245 } else if (op.whitebox_attached()) { 2246 // If WhiteBox wants control, wait for notification of a state 2247 // change in the controller, then try again. Don't wait for 2248 // release of control, since collections may complete while in 2249 // control. Note: This won't recognize a STW full collection 2250 // while waiting; we can't wait on multiple monitors. 2251 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 2252 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 2253 if (ConcurrentGCBreakpoints::is_controlled()) { 2254 ml.wait(); 2255 } 2256 continue; 2257 } 2258 } 2259 2260 // Collection failed and should be retried. 2261 assert(op.transient_failure(), "invariant"); 2262 2263 if (GCLocker::is_active_and_needs_gc()) { 2264 // If GCLocker is active, wait until clear before retrying. 2265 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2266 GCLocker::stall_until_clear(); 2267 } 2268 2269 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2270 } 2271 } 2272 2273 bool G1CollectedHeap::try_collect(GCCause::Cause cause) { 2274 assert_heap_not_locked(); 2275 2276 // Lock to get consistent set of values. 2277 uint gc_count_before; 2278 uint full_gc_count_before; 2279 uint old_marking_started_before; 2280 { 2281 MutexLocker ml(Heap_lock); 2282 gc_count_before = total_collections(); 2283 full_gc_count_before = total_full_collections(); 2284 old_marking_started_before = _old_marking_cycles_started; 2285 } 2286 2287 if (should_do_concurrent_full_gc(cause)) { 2288 return try_collect_concurrently(cause, 2289 gc_count_before, 2290 old_marking_started_before); 2291 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2292 // Indicate failure to be consistent with VMOp failure due to 2293 // another collection slipping in after our gc_count but before 2294 // our request is processed. 2295 return false; 2296 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2297 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2298 2299 // Schedule a standard evacuation pause. We're setting word_size 2300 // to 0 which means that we are not requesting a post-GC allocation. 2301 VM_G1CollectForAllocation op(0, /* word_size */ 2302 gc_count_before, 2303 cause, 2304 policy()->max_pause_time_ms()); 2305 VMThread::execute(&op); 2306 return op.gc_succeeded(); 2307 } else { 2308 // Schedule a Full GC. 2309 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2310 VMThread::execute(&op); 2311 return op.gc_succeeded(); 2312 } 2313 } 2314 2315 bool G1CollectedHeap::is_in(const void* p) const { 2316 if (_hrm->reserved().contains(p)) { 2317 // Given that we know that p is in the reserved space, 2318 // heap_region_containing() should successfully 2319 // return the containing region. 2320 HeapRegion* hr = heap_region_containing(p); 2321 return hr->is_in(p); 2322 } else { 2323 return false; 2324 } 2325 } 2326 2327 #ifdef ASSERT 2328 bool G1CollectedHeap::is_in_exact(const void* p) const { 2329 bool contains = reserved_region().contains(p); 2330 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2331 if (contains && available) { 2332 return true; 2333 } else { 2334 return false; 2335 } 2336 } 2337 #endif 2338 2339 // Iteration functions. 2340 2341 // Iterates an ObjectClosure over all objects within a HeapRegion. 2342 2343 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2344 ObjectClosure* _cl; 2345 public: 2346 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2347 bool do_heap_region(HeapRegion* r) { 2348 if (!r->is_continues_humongous()) { 2349 r->object_iterate(_cl); 2350 } 2351 return false; 2352 } 2353 }; 2354 2355 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2356 IterateObjectClosureRegionClosure blk(cl); 2357 heap_region_iterate(&blk); 2358 } 2359 2360 void G1CollectedHeap::keep_alive(oop obj) { 2361 G1BarrierSet::enqueue(obj); 2362 } 2363 2364 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2365 _hrm->iterate(cl); 2366 } 2367 2368 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2369 HeapRegionClaimer *hrclaimer, 2370 uint worker_id) const { 2371 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2372 } 2373 2374 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2375 HeapRegionClaimer *hrclaimer) const { 2376 _hrm->par_iterate(cl, hrclaimer, 0); 2377 } 2378 2379 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2380 _collection_set.iterate(cl); 2381 } 2382 2383 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2384 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers()); 2385 } 2386 2387 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2388 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2389 } 2390 2391 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2392 HeapRegion* hr = heap_region_containing(addr); 2393 return hr->block_start(addr); 2394 } 2395 2396 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2397 HeapRegion* hr = heap_region_containing(addr); 2398 return hr->block_is_obj(addr); 2399 } 2400 2401 bool G1CollectedHeap::supports_tlab_allocation() const { 2402 return true; 2403 } 2404 2405 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2406 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2407 } 2408 2409 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2410 return _eden.length() * HeapRegion::GrainBytes; 2411 } 2412 2413 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2414 // must be equal to the humongous object limit. 2415 size_t G1CollectedHeap::max_tlab_size() const { 2416 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2417 } 2418 2419 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2420 return _allocator->unsafe_max_tlab_alloc(); 2421 } 2422 2423 size_t G1CollectedHeap::max_capacity() const { 2424 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2425 } 2426 2427 size_t G1CollectedHeap::max_reserved_capacity() const { 2428 return _hrm->max_length() * HeapRegion::GrainBytes; 2429 } 2430 2431 jlong G1CollectedHeap::millis_since_last_gc() { 2432 // See the notes in GenCollectedHeap::millis_since_last_gc() 2433 // for more information about the implementation. 2434 jlong ret_val = (os::javaTimeNanos() - _policy->time_of_last_gc()) / 2435 NANOSECS_PER_MILLISEC; 2436 if (ret_val < 0) { 2437 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 2438 return 0; 2439 } 2440 return ret_val; 2441 } 2442 2443 void G1CollectedHeap::deduplicate_string(oop str) { 2444 assert(java_lang_String::is_instance(str), "invariant"); 2445 2446 if (G1StringDedup::is_enabled()) { 2447 G1StringDedup::deduplicate(str); 2448 } 2449 } 2450 2451 void G1CollectedHeap::prepare_for_verify() { 2452 _verifier->prepare_for_verify(); 2453 } 2454 2455 void G1CollectedHeap::verify(VerifyOption vo) { 2456 _verifier->verify(vo); 2457 } 2458 2459 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2460 return true; 2461 } 2462 2463 bool G1CollectedHeap::is_heterogeneous_heap() const { 2464 return G1Arguments::is_heterogeneous_heap(); 2465 } 2466 2467 class PrintRegionClosure: public HeapRegionClosure { 2468 outputStream* _st; 2469 public: 2470 PrintRegionClosure(outputStream* st) : _st(st) {} 2471 bool do_heap_region(HeapRegion* r) { 2472 r->print_on(_st); 2473 return false; 2474 } 2475 }; 2476 2477 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2478 const HeapRegion* hr, 2479 const VerifyOption vo) const { 2480 switch (vo) { 2481 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2482 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2483 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2484 default: ShouldNotReachHere(); 2485 } 2486 return false; // keep some compilers happy 2487 } 2488 2489 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2490 const VerifyOption vo) const { 2491 switch (vo) { 2492 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2493 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2494 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2495 default: ShouldNotReachHere(); 2496 } 2497 return false; // keep some compilers happy 2498 } 2499 2500 void G1CollectedHeap::print_heap_regions() const { 2501 LogTarget(Trace, gc, heap, region) lt; 2502 if (lt.is_enabled()) { 2503 LogStream ls(lt); 2504 print_regions_on(&ls); 2505 } 2506 } 2507 2508 void G1CollectedHeap::print_on(outputStream* st) const { 2509 st->print(" %-20s", "garbage-first heap"); 2510 if (_hrm != NULL) { 2511 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2512 capacity()/K, used_unlocked()/K); 2513 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2514 p2i(_hrm->reserved().start()), 2515 p2i(_hrm->reserved().end())); 2516 } 2517 st->cr(); 2518 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2519 uint young_regions = young_regions_count(); 2520 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2521 (size_t) young_regions * HeapRegion::GrainBytes / K); 2522 uint survivor_regions = survivor_regions_count(); 2523 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2524 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2525 st->cr(); 2526 if (_numa->is_enabled()) { 2527 uint num_nodes = _numa->num_active_nodes(); 2528 st->print(" remaining free region(s) on each NUMA node: "); 2529 const int* node_ids = _numa->node_ids(); 2530 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2531 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0); 2532 st->print("%d=%u ", node_ids[node_index], num_free_regions); 2533 } 2534 st->cr(); 2535 } 2536 MetaspaceUtils::print_on(st); 2537 } 2538 2539 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2540 if (_hrm == NULL) { 2541 return; 2542 } 2543 2544 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2545 "HS=humongous(starts), HC=humongous(continues), " 2546 "CS=collection set, F=free, " 2547 "OA=open archive, CA=closed archive, " 2548 "TAMS=top-at-mark-start (previous, next)"); 2549 PrintRegionClosure blk(st); 2550 heap_region_iterate(&blk); 2551 } 2552 2553 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2554 print_on(st); 2555 2556 // Print the per-region information. 2557 if (_hrm != NULL) { 2558 st->cr(); 2559 print_regions_on(st); 2560 } 2561 } 2562 2563 void G1CollectedHeap::print_on_error(outputStream* st) const { 2564 this->CollectedHeap::print_on_error(st); 2565 2566 if (_cm != NULL) { 2567 st->cr(); 2568 _cm->print_on_error(st); 2569 } 2570 } 2571 2572 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2573 workers()->threads_do(tc); 2574 tc->do_thread(_cm_thread); 2575 _cm->threads_do(tc); 2576 _cr->threads_do(tc); 2577 tc->do_thread(_young_gen_sampling_thread); 2578 if (G1StringDedup::is_enabled()) { 2579 G1StringDedup::threads_do(tc); 2580 } 2581 } 2582 2583 void G1CollectedHeap::print_tracing_info() const { 2584 rem_set()->print_summary_info(); 2585 concurrent_mark()->print_summary_info(); 2586 } 2587 2588 #ifndef PRODUCT 2589 // Helpful for debugging RSet issues. 2590 2591 class PrintRSetsClosure : public HeapRegionClosure { 2592 private: 2593 const char* _msg; 2594 size_t _occupied_sum; 2595 2596 public: 2597 bool do_heap_region(HeapRegion* r) { 2598 HeapRegionRemSet* hrrs = r->rem_set(); 2599 size_t occupied = hrrs->occupied(); 2600 _occupied_sum += occupied; 2601 2602 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2603 if (occupied == 0) { 2604 tty->print_cr(" RSet is empty"); 2605 } else { 2606 hrrs->print(); 2607 } 2608 tty->print_cr("----------"); 2609 return false; 2610 } 2611 2612 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2613 tty->cr(); 2614 tty->print_cr("========================================"); 2615 tty->print_cr("%s", msg); 2616 tty->cr(); 2617 } 2618 2619 ~PrintRSetsClosure() { 2620 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2621 tty->print_cr("========================================"); 2622 tty->cr(); 2623 } 2624 }; 2625 2626 void G1CollectedHeap::print_cset_rsets() { 2627 PrintRSetsClosure cl("Printing CSet RSets"); 2628 collection_set_iterate_all(&cl); 2629 } 2630 2631 void G1CollectedHeap::print_all_rsets() { 2632 PrintRSetsClosure cl("Printing All RSets");; 2633 heap_region_iterate(&cl); 2634 } 2635 #endif // PRODUCT 2636 2637 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2638 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2639 } 2640 2641 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2642 2643 size_t eden_used_bytes = _eden.used_bytes(); 2644 size_t survivor_used_bytes = _survivor.used_bytes(); 2645 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2646 2647 size_t eden_capacity_bytes = 2648 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2649 2650 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2651 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2652 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2653 } 2654 2655 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2656 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2657 stats->unused(), stats->used(), stats->region_end_waste(), 2658 stats->regions_filled(), stats->direct_allocated(), 2659 stats->failure_used(), stats->failure_waste()); 2660 } 2661 2662 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2663 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2664 gc_tracer->report_gc_heap_summary(when, heap_summary); 2665 2666 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2667 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2668 } 2669 2670 void G1CollectedHeap::gc_prologue(bool full) { 2671 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2672 2673 // This summary needs to be printed before incrementing total collections. 2674 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2675 2676 // Update common counters. 2677 increment_total_collections(full /* full gc */); 2678 if (full || collector_state()->in_initial_mark_gc()) { 2679 increment_old_marking_cycles_started(); 2680 } 2681 2682 // Fill TLAB's and such 2683 { 2684 Ticks start = Ticks::now(); 2685 ensure_parsability(true); 2686 Tickspan dt = Ticks::now() - start; 2687 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS); 2688 } 2689 2690 if (!full) { 2691 // Flush dirty card queues to qset, so later phases don't need to account 2692 // for partially filled per-thread queues and such. Not needed for full 2693 // collections, which ignore those logs. 2694 Ticks start = Ticks::now(); 2695 G1BarrierSet::dirty_card_queue_set().concatenate_logs(); 2696 Tickspan dt = Ticks::now() - start; 2697 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS); 2698 } 2699 } 2700 2701 void G1CollectedHeap::gc_epilogue(bool full) { 2702 // Update common counters. 2703 if (full) { 2704 // Update the number of full collections that have been completed. 2705 increment_old_marking_cycles_completed(false /* concurrent */); 2706 } 2707 2708 // We are at the end of the GC. Total collections has already been increased. 2709 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2710 2711 // FIXME: what is this about? 2712 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2713 // is set. 2714 #if COMPILER2_OR_JVMCI 2715 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2716 #endif 2717 2718 double start = os::elapsedTime(); 2719 resize_all_tlabs(); 2720 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2721 2722 MemoryService::track_memory_usage(); 2723 // We have just completed a GC. Update the soft reference 2724 // policy with the new heap occupancy 2725 Universe::update_heap_info_at_gc(); 2726 2727 // Print NUMA statistics. 2728 _numa->print_statistics(); 2729 } 2730 2731 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2732 LogTarget(Trace, gc, heap, verify) lt; 2733 2734 if (lt.is_enabled()) { 2735 LogStream ls(lt); 2736 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2737 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2738 heap_region_iterate(&cl); 2739 } 2740 } 2741 2742 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2743 uint gc_count_before, 2744 bool* succeeded, 2745 GCCause::Cause gc_cause) { 2746 assert_heap_not_locked_and_not_at_safepoint(); 2747 VM_G1CollectForAllocation op(word_size, 2748 gc_count_before, 2749 gc_cause, 2750 policy()->max_pause_time_ms()); 2751 VMThread::execute(&op); 2752 2753 HeapWord* result = op.result(); 2754 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2755 assert(result == NULL || ret_succeeded, 2756 "the result should be NULL if the VM did not succeed"); 2757 *succeeded = ret_succeeded; 2758 2759 assert_heap_not_locked(); 2760 return result; 2761 } 2762 2763 void G1CollectedHeap::do_concurrent_mark() { 2764 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2765 if (!_cm_thread->in_progress()) { 2766 _cm_thread->set_started(); 2767 CGC_lock->notify(); 2768 } 2769 } 2770 2771 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2772 // We don't nominate objects with many remembered set entries, on 2773 // the assumption that such objects are likely still live. 2774 HeapRegionRemSet* rem_set = r->rem_set(); 2775 2776 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2777 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2778 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2779 } 2780 2781 #ifndef PRODUCT 2782 void G1CollectedHeap::verify_region_attr_remset_update() { 2783 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2784 public: 2785 virtual bool do_heap_region(HeapRegion* r) { 2786 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2787 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2788 assert(r->rem_set()->is_tracked() == needs_remset_update, 2789 "Region %u remset tracking status (%s) different to region attribute (%s)", 2790 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2791 return false; 2792 } 2793 } cl; 2794 heap_region_iterate(&cl); 2795 } 2796 #endif 2797 2798 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2799 public: 2800 bool do_heap_region(HeapRegion* hr) { 2801 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2802 hr->verify_rem_set(); 2803 } 2804 return false; 2805 } 2806 }; 2807 2808 uint G1CollectedHeap::num_task_queues() const { 2809 return _task_queues->size(); 2810 } 2811 2812 #if TASKQUEUE_STATS 2813 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2814 st->print_raw_cr("GC Task Stats"); 2815 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2816 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2817 } 2818 2819 void G1CollectedHeap::print_taskqueue_stats() const { 2820 if (!log_is_enabled(Trace, gc, task, stats)) { 2821 return; 2822 } 2823 Log(gc, task, stats) log; 2824 ResourceMark rm; 2825 LogStream ls(log.trace()); 2826 outputStream* st = &ls; 2827 2828 print_taskqueue_stats_hdr(st); 2829 2830 TaskQueueStats totals; 2831 const uint n = num_task_queues(); 2832 for (uint i = 0; i < n; ++i) { 2833 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2834 totals += task_queue(i)->stats; 2835 } 2836 st->print_raw("tot "); totals.print(st); st->cr(); 2837 2838 DEBUG_ONLY(totals.verify()); 2839 } 2840 2841 void G1CollectedHeap::reset_taskqueue_stats() { 2842 const uint n = num_task_queues(); 2843 for (uint i = 0; i < n; ++i) { 2844 task_queue(i)->stats.reset(); 2845 } 2846 } 2847 #endif // TASKQUEUE_STATS 2848 2849 void G1CollectedHeap::wait_for_root_region_scanning() { 2850 double scan_wait_start = os::elapsedTime(); 2851 // We have to wait until the CM threads finish scanning the 2852 // root regions as it's the only way to ensure that all the 2853 // objects on them have been correctly scanned before we start 2854 // moving them during the GC. 2855 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2856 double wait_time_ms = 0.0; 2857 if (waited) { 2858 double scan_wait_end = os::elapsedTime(); 2859 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2860 } 2861 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2862 } 2863 2864 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2865 private: 2866 G1HRPrinter* _hr_printer; 2867 public: 2868 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2869 2870 virtual bool do_heap_region(HeapRegion* r) { 2871 _hr_printer->cset(r); 2872 return false; 2873 } 2874 }; 2875 2876 void G1CollectedHeap::start_new_collection_set() { 2877 double start = os::elapsedTime(); 2878 2879 collection_set()->start_incremental_building(); 2880 2881 clear_region_attr(); 2882 2883 guarantee(_eden.length() == 0, "eden should have been cleared"); 2884 policy()->transfer_survivors_to_cset(survivor()); 2885 2886 // We redo the verification but now wrt to the new CSet which 2887 // has just got initialized after the previous CSet was freed. 2888 _cm->verify_no_collection_set_oops(); 2889 2890 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2891 } 2892 2893 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2894 2895 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2896 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2897 collection_set()->optional_region_length()); 2898 2899 _cm->verify_no_collection_set_oops(); 2900 2901 if (_hr_printer.is_active()) { 2902 G1PrintCollectionSetClosure cl(&_hr_printer); 2903 _collection_set.iterate(&cl); 2904 _collection_set.iterate_optional(&cl); 2905 } 2906 } 2907 2908 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2909 if (collector_state()->in_initial_mark_gc()) { 2910 return G1HeapVerifier::G1VerifyConcurrentStart; 2911 } else if (collector_state()->in_young_only_phase()) { 2912 return G1HeapVerifier::G1VerifyYoungNormal; 2913 } else { 2914 return G1HeapVerifier::G1VerifyMixed; 2915 } 2916 } 2917 2918 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2919 if (VerifyRememberedSets) { 2920 log_info(gc, verify)("[Verifying RemSets before GC]"); 2921 VerifyRegionRemSetClosure v_cl; 2922 heap_region_iterate(&v_cl); 2923 } 2924 _verifier->verify_before_gc(type); 2925 _verifier->check_bitmaps("GC Start"); 2926 verify_numa_regions("GC Start"); 2927 } 2928 2929 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2930 if (VerifyRememberedSets) { 2931 log_info(gc, verify)("[Verifying RemSets after GC]"); 2932 VerifyRegionRemSetClosure v_cl; 2933 heap_region_iterate(&v_cl); 2934 } 2935 _verifier->verify_after_gc(type); 2936 _verifier->check_bitmaps("GC End"); 2937 verify_numa_regions("GC End"); 2938 } 2939 2940 void G1CollectedHeap::expand_heap_after_young_collection(){ 2941 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2942 if (expand_bytes > 0) { 2943 // No need for an ergo logging here, 2944 // expansion_amount() does this when it returns a value > 0. 2945 double expand_ms; 2946 if (!expand(expand_bytes, _workers, &expand_ms)) { 2947 // We failed to expand the heap. Cannot do anything about it. 2948 } 2949 phase_times()->record_expand_heap_time(expand_ms); 2950 } 2951 } 2952 2953 const char* G1CollectedHeap::young_gc_name() const { 2954 if (collector_state()->in_initial_mark_gc()) { 2955 return "Pause Young (Concurrent Start)"; 2956 } else if (collector_state()->in_young_only_phase()) { 2957 if (collector_state()->in_young_gc_before_mixed()) { 2958 return "Pause Young (Prepare Mixed)"; 2959 } else { 2960 return "Pause Young (Normal)"; 2961 } 2962 } else { 2963 return "Pause Young (Mixed)"; 2964 } 2965 } 2966 2967 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2968 assert_at_safepoint_on_vm_thread(); 2969 guarantee(!is_gc_active(), "collection is not reentrant"); 2970 2971 if (GCLocker::check_active_before_gc()) { 2972 return false; 2973 } 2974 2975 do_collection_pause_at_safepoint_helper(target_pause_time_ms); 2976 if (should_upgrade_to_full_gc(gc_cause())) { 2977 log_info(gc, ergo)("Attempting maximally compacting collection"); 2978 bool result = do_full_collection(false /* explicit gc */, 2979 true /* clear_all_soft_refs */); 2980 // do_full_collection only fails if blocked by GC locker, but 2981 // we've already checked for that above. 2982 assert(result, "invariant"); 2983 } 2984 return true; 2985 } 2986 2987 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) { 2988 GCIdMark gc_id_mark; 2989 2990 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2991 ResourceMark rm; 2992 2993 policy()->note_gc_start(); 2994 2995 _gc_timer_stw->register_gc_start(); 2996 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2997 2998 wait_for_root_region_scanning(); 2999 3000 print_heap_before_gc(); 3001 print_heap_regions(); 3002 trace_heap_before_gc(_gc_tracer_stw); 3003 3004 _verifier->verify_region_sets_optional(); 3005 _verifier->verify_dirty_young_regions(); 3006 3007 // We should not be doing initial mark unless the conc mark thread is running 3008 if (!_cm_thread->should_terminate()) { 3009 // This call will decide whether this pause is an initial-mark 3010 // pause. If it is, in_initial_mark_gc() will return true 3011 // for the duration of this pause. 3012 policy()->decide_on_conc_mark_initiation(); 3013 } 3014 3015 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3016 assert(!collector_state()->in_initial_mark_gc() || 3017 collector_state()->in_young_only_phase(), "sanity"); 3018 // We also do not allow mixed GCs during marking. 3019 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 3020 3021 // Record whether this pause is an initial mark. When the current 3022 // thread has completed its logging output and it's safe to signal 3023 // the CM thread, the flag's value in the policy has been reset. 3024 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 3025 if (should_start_conc_mark) { 3026 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3027 } 3028 3029 // Inner scope for scope based logging, timers, and stats collection 3030 { 3031 G1EvacuationInfo evacuation_info; 3032 3033 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3034 3035 GCTraceCPUTime tcpu; 3036 3037 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3038 3039 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3040 workers()->active_workers(), 3041 Threads::number_of_non_daemon_threads()); 3042 active_workers = workers()->update_active_workers(active_workers); 3043 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3044 3045 G1MonitoringScope ms(g1mm(), 3046 false /* full_gc */, 3047 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3048 3049 G1HeapTransition heap_transition(this); 3050 3051 { 3052 IsGCActiveMark x; 3053 3054 gc_prologue(false); 3055 3056 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3057 verify_before_young_collection(verify_type); 3058 3059 { 3060 // The elapsed time induced by the start time below deliberately elides 3061 // the possible verification above. 3062 double sample_start_time_sec = os::elapsedTime(); 3063 3064 // Please see comment in g1CollectedHeap.hpp and 3065 // G1CollectedHeap::ref_processing_init() to see how 3066 // reference processing currently works in G1. 3067 _ref_processor_stw->enable_discovery(); 3068 3069 // We want to temporarily turn off discovery by the 3070 // CM ref processor, if necessary, and turn it back on 3071 // on again later if we do. Using a scoped 3072 // NoRefDiscovery object will do this. 3073 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3074 3075 policy()->record_collection_pause_start(sample_start_time_sec); 3076 3077 // Forget the current allocation region (we might even choose it to be part 3078 // of the collection set!). 3079 _allocator->release_mutator_alloc_regions(); 3080 3081 calculate_collection_set(evacuation_info, target_pause_time_ms); 3082 3083 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3084 G1ParScanThreadStateSet per_thread_states(this, 3085 &rdcqs, 3086 workers()->active_workers(), 3087 collection_set()->young_region_length(), 3088 collection_set()->optional_region_length()); 3089 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3090 3091 // Actually do the work... 3092 evacuate_initial_collection_set(&per_thread_states); 3093 3094 if (_collection_set.optional_region_length() != 0) { 3095 evacuate_optional_collection_set(&per_thread_states); 3096 } 3097 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3098 3099 start_new_collection_set(); 3100 3101 _survivor_evac_stats.adjust_desired_plab_sz(); 3102 _old_evac_stats.adjust_desired_plab_sz(); 3103 3104 if (should_start_conc_mark) { 3105 // We have to do this before we notify the CM threads that 3106 // they can start working to make sure that all the 3107 // appropriate initialization is done on the CM object. 3108 concurrent_mark()->post_initial_mark(); 3109 // Note that we don't actually trigger the CM thread at 3110 // this point. We do that later when we're sure that 3111 // the current thread has completed its logging output. 3112 } 3113 3114 allocate_dummy_regions(); 3115 3116 _allocator->init_mutator_alloc_regions(); 3117 3118 expand_heap_after_young_collection(); 3119 3120 double sample_end_time_sec = os::elapsedTime(); 3121 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3122 policy()->record_collection_pause_end(pause_time_ms); 3123 } 3124 3125 verify_after_young_collection(verify_type); 3126 3127 gc_epilogue(false); 3128 } 3129 3130 // Print the remainder of the GC log output. 3131 if (evacuation_failed()) { 3132 log_info(gc)("To-space exhausted"); 3133 } 3134 3135 policy()->print_phases(); 3136 heap_transition.print(); 3137 3138 _hrm->verify_optional(); 3139 _verifier->verify_region_sets_optional(); 3140 3141 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3142 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3143 3144 print_heap_after_gc(); 3145 print_heap_regions(); 3146 trace_heap_after_gc(_gc_tracer_stw); 3147 3148 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3149 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3150 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3151 // before any GC notifications are raised. 3152 g1mm()->update_sizes(); 3153 3154 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3155 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3156 _gc_timer_stw->register_gc_end(); 3157 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3158 } 3159 // It should now be safe to tell the concurrent mark thread to start 3160 // without its logging output interfering with the logging output 3161 // that came from the pause. 3162 3163 if (should_start_conc_mark) { 3164 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3165 // thread(s) could be running concurrently with us. Make sure that anything 3166 // after this point does not assume that we are the only GC thread running. 3167 // Note: of course, the actual marking work will not start until the safepoint 3168 // itself is released in SuspendibleThreadSet::desynchronize(). 3169 do_concurrent_mark(); 3170 ConcurrentGCBreakpoints::notify_idle_to_active(); 3171 } 3172 } 3173 3174 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3175 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3176 workers()->run_task(&rsfp_task); 3177 } 3178 3179 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3180 double remove_self_forwards_start = os::elapsedTime(); 3181 3182 remove_self_forwarding_pointers(rdcqs); 3183 _preserved_marks_set.restore(workers()); 3184 3185 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3186 } 3187 3188 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3189 if (!_evacuation_failed) { 3190 _evacuation_failed = true; 3191 } 3192 3193 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3194 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3195 } 3196 3197 bool G1ParEvacuateFollowersClosure::offer_termination() { 3198 EventGCPhaseParallel event; 3199 G1ParScanThreadState* const pss = par_scan_state(); 3200 start_term_time(); 3201 const bool res = terminator()->offer_termination(); 3202 end_term_time(); 3203 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3204 return res; 3205 } 3206 3207 void G1ParEvacuateFollowersClosure::do_void() { 3208 EventGCPhaseParallel event; 3209 G1ParScanThreadState* const pss = par_scan_state(); 3210 pss->trim_queue(); 3211 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3212 do { 3213 EventGCPhaseParallel event; 3214 pss->steal_and_trim_queue(queues()); 3215 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3216 } while (!offer_termination()); 3217 } 3218 3219 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3220 bool class_unloading_occurred) { 3221 uint num_workers = workers()->active_workers(); 3222 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3223 workers()->run_task(&unlink_task); 3224 } 3225 3226 // Clean string dedup data structures. 3227 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3228 // record the durations of the phases. Hence the almost-copy. 3229 class G1StringDedupCleaningTask : public AbstractGangTask { 3230 BoolObjectClosure* _is_alive; 3231 OopClosure* _keep_alive; 3232 G1GCPhaseTimes* _phase_times; 3233 3234 public: 3235 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3236 OopClosure* keep_alive, 3237 G1GCPhaseTimes* phase_times) : 3238 AbstractGangTask("Partial Cleaning Task"), 3239 _is_alive(is_alive), 3240 _keep_alive(keep_alive), 3241 _phase_times(phase_times) 3242 { 3243 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3244 StringDedup::gc_prologue(true); 3245 } 3246 3247 ~G1StringDedupCleaningTask() { 3248 StringDedup::gc_epilogue(); 3249 } 3250 3251 void work(uint worker_id) { 3252 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3253 { 3254 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3255 StringDedupQueue::unlink_or_oops_do(&cl); 3256 } 3257 { 3258 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3259 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3260 } 3261 } 3262 }; 3263 3264 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3265 OopClosure* keep_alive, 3266 G1GCPhaseTimes* phase_times) { 3267 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3268 workers()->run_task(&cl); 3269 } 3270 3271 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3272 private: 3273 G1RedirtyCardsQueueSet* _qset; 3274 G1CollectedHeap* _g1h; 3275 BufferNode* volatile _nodes; 3276 3277 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3278 size_t buffer_size = _qset->buffer_size(); 3279 BufferNode* next = Atomic::load(&_nodes); 3280 while (next != NULL) { 3281 BufferNode* node = next; 3282 next = Atomic::cmpxchg(&_nodes, node, node->next()); 3283 if (next == node) { 3284 cl->apply_to_buffer(node, buffer_size, worker_id); 3285 next = node->next(); 3286 } 3287 } 3288 } 3289 3290 public: 3291 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3292 AbstractGangTask("Redirty Cards"), 3293 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3294 3295 virtual void work(uint worker_id) { 3296 G1GCPhaseTimes* p = _g1h->phase_times(); 3297 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3298 3299 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3300 par_apply(&cl, worker_id); 3301 3302 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3303 } 3304 }; 3305 3306 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3307 double redirty_logged_cards_start = os::elapsedTime(); 3308 3309 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3310 workers()->run_task(&redirty_task); 3311 3312 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3313 dcq.merge_bufferlists(rdcqs); 3314 3315 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3316 } 3317 3318 // Weak Reference Processing support 3319 3320 bool G1STWIsAliveClosure::do_object_b(oop p) { 3321 // An object is reachable if it is outside the collection set, 3322 // or is inside and copied. 3323 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3324 } 3325 3326 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3327 assert(obj != NULL, "must not be NULL"); 3328 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3329 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3330 // may falsely indicate that this is not the case here: however the collection set only 3331 // contains old regions when concurrent mark is not running. 3332 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3333 } 3334 3335 // Non Copying Keep Alive closure 3336 class G1KeepAliveClosure: public OopClosure { 3337 G1CollectedHeap*_g1h; 3338 public: 3339 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3340 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3341 void do_oop(oop* p) { 3342 oop obj = *p; 3343 assert(obj != NULL, "the caller should have filtered out NULL values"); 3344 3345 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3346 if (!region_attr.is_in_cset_or_humongous()) { 3347 return; 3348 } 3349 if (region_attr.is_in_cset()) { 3350 assert( obj->is_forwarded(), "invariant" ); 3351 *p = obj->forwardee(); 3352 } else { 3353 assert(!obj->is_forwarded(), "invariant" ); 3354 assert(region_attr.is_humongous(), 3355 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3356 _g1h->set_humongous_is_live(obj); 3357 } 3358 } 3359 }; 3360 3361 // Copying Keep Alive closure - can be called from both 3362 // serial and parallel code as long as different worker 3363 // threads utilize different G1ParScanThreadState instances 3364 // and different queues. 3365 3366 class G1CopyingKeepAliveClosure: public OopClosure { 3367 G1CollectedHeap* _g1h; 3368 G1ParScanThreadState* _par_scan_state; 3369 3370 public: 3371 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3372 G1ParScanThreadState* pss): 3373 _g1h(g1h), 3374 _par_scan_state(pss) 3375 {} 3376 3377 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3378 virtual void do_oop( oop* p) { do_oop_work(p); } 3379 3380 template <class T> void do_oop_work(T* p) { 3381 oop obj = RawAccess<>::oop_load(p); 3382 3383 if (_g1h->is_in_cset_or_humongous(obj)) { 3384 // If the referent object has been forwarded (either copied 3385 // to a new location or to itself in the event of an 3386 // evacuation failure) then we need to update the reference 3387 // field and, if both reference and referent are in the G1 3388 // heap, update the RSet for the referent. 3389 // 3390 // If the referent has not been forwarded then we have to keep 3391 // it alive by policy. Therefore we have copy the referent. 3392 // 3393 // When the queue is drained (after each phase of reference processing) 3394 // the object and it's followers will be copied, the reference field set 3395 // to point to the new location, and the RSet updated. 3396 _par_scan_state->push_on_queue(ScannerTask(p)); 3397 } 3398 } 3399 }; 3400 3401 // Serial drain queue closure. Called as the 'complete_gc' 3402 // closure for each discovered list in some of the 3403 // reference processing phases. 3404 3405 class G1STWDrainQueueClosure: public VoidClosure { 3406 protected: 3407 G1CollectedHeap* _g1h; 3408 G1ParScanThreadState* _par_scan_state; 3409 3410 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3411 3412 public: 3413 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3414 _g1h(g1h), 3415 _par_scan_state(pss) 3416 { } 3417 3418 void do_void() { 3419 G1ParScanThreadState* const pss = par_scan_state(); 3420 pss->trim_queue(); 3421 } 3422 }; 3423 3424 // Parallel Reference Processing closures 3425 3426 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3427 // processing during G1 evacuation pauses. 3428 3429 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3430 private: 3431 G1CollectedHeap* _g1h; 3432 G1ParScanThreadStateSet* _pss; 3433 G1ScannerTasksQueueSet* _queues; 3434 WorkGang* _workers; 3435 3436 public: 3437 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3438 G1ParScanThreadStateSet* per_thread_states, 3439 WorkGang* workers, 3440 G1ScannerTasksQueueSet *task_queues) : 3441 _g1h(g1h), 3442 _pss(per_thread_states), 3443 _queues(task_queues), 3444 _workers(workers) 3445 { 3446 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3447 } 3448 3449 // Executes the given task using concurrent marking worker threads. 3450 virtual void execute(ProcessTask& task, uint ergo_workers); 3451 }; 3452 3453 // Gang task for possibly parallel reference processing 3454 3455 class G1STWRefProcTaskProxy: public AbstractGangTask { 3456 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3457 ProcessTask& _proc_task; 3458 G1CollectedHeap* _g1h; 3459 G1ParScanThreadStateSet* _pss; 3460 G1ScannerTasksQueueSet* _task_queues; 3461 TaskTerminator* _terminator; 3462 3463 public: 3464 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3465 G1CollectedHeap* g1h, 3466 G1ParScanThreadStateSet* per_thread_states, 3467 G1ScannerTasksQueueSet *task_queues, 3468 TaskTerminator* terminator) : 3469 AbstractGangTask("Process reference objects in parallel"), 3470 _proc_task(proc_task), 3471 _g1h(g1h), 3472 _pss(per_thread_states), 3473 _task_queues(task_queues), 3474 _terminator(terminator) 3475 {} 3476 3477 virtual void work(uint worker_id) { 3478 // The reference processing task executed by a single worker. 3479 ResourceMark rm; 3480 HandleMark hm; 3481 3482 G1STWIsAliveClosure is_alive(_g1h); 3483 3484 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3485 pss->set_ref_discoverer(NULL); 3486 3487 // Keep alive closure. 3488 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3489 3490 // Complete GC closure 3491 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3492 3493 // Call the reference processing task's work routine. 3494 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3495 3496 // Note we cannot assert that the refs array is empty here as not all 3497 // of the processing tasks (specifically phase2 - pp2_work) execute 3498 // the complete_gc closure (which ordinarily would drain the queue) so 3499 // the queue may not be empty. 3500 } 3501 }; 3502 3503 // Driver routine for parallel reference processing. 3504 // Creates an instance of the ref processing gang 3505 // task and has the worker threads execute it. 3506 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3507 assert(_workers != NULL, "Need parallel worker threads."); 3508 3509 assert(_workers->active_workers() >= ergo_workers, 3510 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3511 ergo_workers, _workers->active_workers()); 3512 TaskTerminator terminator(ergo_workers, _queues); 3513 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3514 3515 _workers->run_task(&proc_task_proxy, ergo_workers); 3516 } 3517 3518 // End of weak reference support closures 3519 3520 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3521 double ref_proc_start = os::elapsedTime(); 3522 3523 ReferenceProcessor* rp = _ref_processor_stw; 3524 assert(rp->discovery_enabled(), "should have been enabled"); 3525 3526 // Closure to test whether a referent is alive. 3527 G1STWIsAliveClosure is_alive(this); 3528 3529 // Even when parallel reference processing is enabled, the processing 3530 // of JNI refs is serial and performed serially by the current thread 3531 // rather than by a worker. The following PSS will be used for processing 3532 // JNI refs. 3533 3534 // Use only a single queue for this PSS. 3535 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3536 pss->set_ref_discoverer(NULL); 3537 assert(pss->queue_is_empty(), "pre-condition"); 3538 3539 // Keep alive closure. 3540 G1CopyingKeepAliveClosure keep_alive(this, pss); 3541 3542 // Serial Complete GC closure 3543 G1STWDrainQueueClosure drain_queue(this, pss); 3544 3545 // Setup the soft refs policy... 3546 rp->setup_policy(false); 3547 3548 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3549 3550 ReferenceProcessorStats stats; 3551 if (!rp->processing_is_mt()) { 3552 // Serial reference processing... 3553 stats = rp->process_discovered_references(&is_alive, 3554 &keep_alive, 3555 &drain_queue, 3556 NULL, 3557 pt); 3558 } else { 3559 uint no_of_gc_workers = workers()->active_workers(); 3560 3561 // Parallel reference processing 3562 assert(no_of_gc_workers <= rp->max_num_queues(), 3563 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3564 no_of_gc_workers, rp->max_num_queues()); 3565 3566 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3567 stats = rp->process_discovered_references(&is_alive, 3568 &keep_alive, 3569 &drain_queue, 3570 &par_task_executor, 3571 pt); 3572 } 3573 3574 _gc_tracer_stw->report_gc_reference_stats(stats); 3575 3576 // We have completed copying any necessary live referent objects. 3577 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3578 3579 make_pending_list_reachable(); 3580 3581 assert(!rp->discovery_enabled(), "Postcondition"); 3582 rp->verify_no_references_recorded(); 3583 3584 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3585 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3586 } 3587 3588 void G1CollectedHeap::make_pending_list_reachable() { 3589 if (collector_state()->in_initial_mark_gc()) { 3590 oop pll_head = Universe::reference_pending_list(); 3591 if (pll_head != NULL) { 3592 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3593 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3594 } 3595 } 3596 } 3597 3598 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3599 Ticks start = Ticks::now(); 3600 per_thread_states->flush(); 3601 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds()); 3602 } 3603 3604 class G1PrepareEvacuationTask : public AbstractGangTask { 3605 class G1PrepareRegionsClosure : public HeapRegionClosure { 3606 G1CollectedHeap* _g1h; 3607 G1PrepareEvacuationTask* _parent_task; 3608 size_t _worker_humongous_total; 3609 size_t _worker_humongous_candidates; 3610 3611 bool humongous_region_is_candidate(HeapRegion* region) const { 3612 assert(region->is_starts_humongous(), "Must start a humongous object"); 3613 3614 oop obj = oop(region->bottom()); 3615 3616 // Dead objects cannot be eager reclaim candidates. Due to class 3617 // unloading it is unsafe to query their classes so we return early. 3618 if (_g1h->is_obj_dead(obj, region)) { 3619 return false; 3620 } 3621 3622 // If we do not have a complete remembered set for the region, then we can 3623 // not be sure that we have all references to it. 3624 if (!region->rem_set()->is_complete()) { 3625 return false; 3626 } 3627 // Candidate selection must satisfy the following constraints 3628 // while concurrent marking is in progress: 3629 // 3630 // * In order to maintain SATB invariants, an object must not be 3631 // reclaimed if it was allocated before the start of marking and 3632 // has not had its references scanned. Such an object must have 3633 // its references (including type metadata) scanned to ensure no 3634 // live objects are missed by the marking process. Objects 3635 // allocated after the start of concurrent marking don't need to 3636 // be scanned. 3637 // 3638 // * An object must not be reclaimed if it is on the concurrent 3639 // mark stack. Objects allocated after the start of concurrent 3640 // marking are never pushed on the mark stack. 3641 // 3642 // Nominating only objects allocated after the start of concurrent 3643 // marking is sufficient to meet both constraints. This may miss 3644 // some objects that satisfy the constraints, but the marking data 3645 // structures don't support efficiently performing the needed 3646 // additional tests or scrubbing of the mark stack. 3647 // 3648 // However, we presently only nominate is_typeArray() objects. 3649 // A humongous object containing references induces remembered 3650 // set entries on other regions. In order to reclaim such an 3651 // object, those remembered sets would need to be cleaned up. 3652 // 3653 // We also treat is_typeArray() objects specially, allowing them 3654 // to be reclaimed even if allocated before the start of 3655 // concurrent mark. For this we rely on mark stack insertion to 3656 // exclude is_typeArray() objects, preventing reclaiming an object 3657 // that is in the mark stack. We also rely on the metadata for 3658 // such objects to be built-in and so ensured to be kept live. 3659 // Frequent allocation and drop of large binary blobs is an 3660 // important use case for eager reclaim, and this special handling 3661 // may reduce needed headroom. 3662 3663 return obj->is_typeArray() && 3664 _g1h->is_potential_eager_reclaim_candidate(region); 3665 } 3666 3667 public: 3668 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) : 3669 _g1h(g1h), 3670 _parent_task(parent_task), 3671 _worker_humongous_total(0), 3672 _worker_humongous_candidates(0) { } 3673 3674 ~G1PrepareRegionsClosure() { 3675 _parent_task->add_humongous_candidates(_worker_humongous_candidates); 3676 _parent_task->add_humongous_total(_worker_humongous_total); 3677 } 3678 3679 virtual bool do_heap_region(HeapRegion* hr) { 3680 // First prepare the region for scanning 3681 _g1h->rem_set()->prepare_region_for_scan(hr); 3682 3683 // Now check if region is a humongous candidate 3684 if (!hr->is_starts_humongous()) { 3685 _g1h->register_region_with_region_attr(hr); 3686 return false; 3687 } 3688 3689 uint index = hr->hrm_index(); 3690 if (humongous_region_is_candidate(hr)) { 3691 _g1h->set_humongous_reclaim_candidate(index, true); 3692 _g1h->register_humongous_region_with_region_attr(index); 3693 _worker_humongous_candidates++; 3694 // We will later handle the remembered sets of these regions. 3695 } else { 3696 _g1h->set_humongous_reclaim_candidate(index, false); 3697 _g1h->register_region_with_region_attr(hr); 3698 } 3699 _worker_humongous_total++; 3700 3701 return false; 3702 } 3703 }; 3704 3705 G1CollectedHeap* _g1h; 3706 HeapRegionClaimer _claimer; 3707 volatile size_t _humongous_total; 3708 volatile size_t _humongous_candidates; 3709 public: 3710 G1PrepareEvacuationTask(G1CollectedHeap* g1h) : 3711 AbstractGangTask("Prepare Evacuation"), 3712 _g1h(g1h), 3713 _claimer(_g1h->workers()->active_workers()), 3714 _humongous_total(0), 3715 _humongous_candidates(0) { } 3716 3717 ~G1PrepareEvacuationTask() { 3718 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0); 3719 } 3720 3721 void work(uint worker_id) { 3722 G1PrepareRegionsClosure cl(_g1h, this); 3723 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id); 3724 } 3725 3726 void add_humongous_candidates(size_t candidates) { 3727 Atomic::add(&_humongous_candidates, candidates); 3728 } 3729 3730 void add_humongous_total(size_t total) { 3731 Atomic::add(&_humongous_total, total); 3732 } 3733 3734 size_t humongous_candidates() { 3735 return _humongous_candidates; 3736 } 3737 3738 size_t humongous_total() { 3739 return _humongous_total; 3740 } 3741 }; 3742 3743 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3744 _bytes_used_during_gc = 0; 3745 3746 _expand_heap_after_alloc_failure = true; 3747 _evacuation_failed = false; 3748 3749 // Disable the hot card cache. 3750 _hot_card_cache->reset_hot_cache_claimed_index(); 3751 _hot_card_cache->set_use_cache(false); 3752 3753 // Initialize the GC alloc regions. 3754 _allocator->init_gc_alloc_regions(evacuation_info); 3755 3756 { 3757 Ticks start = Ticks::now(); 3758 rem_set()->prepare_for_scan_heap_roots(); 3759 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3760 } 3761 3762 { 3763 G1PrepareEvacuationTask g1_prep_task(this); 3764 Tickspan task_time = run_task(&g1_prep_task); 3765 3766 phase_times()->record_register_regions(task_time.seconds() * 1000.0, 3767 g1_prep_task.humongous_total(), 3768 g1_prep_task.humongous_candidates()); 3769 } 3770 3771 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3772 _preserved_marks_set.assert_empty(); 3773 3774 #if COMPILER2_OR_JVMCI 3775 DerivedPointerTable::clear(); 3776 #endif 3777 3778 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3779 if (collector_state()->in_initial_mark_gc()) { 3780 concurrent_mark()->pre_initial_mark(); 3781 3782 double start_clear_claimed_marks = os::elapsedTime(); 3783 3784 ClassLoaderDataGraph::clear_claimed_marks(); 3785 3786 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3787 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3788 } 3789 3790 // Should G1EvacuationFailureALot be in effect for this GC? 3791 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3792 } 3793 3794 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3795 protected: 3796 G1CollectedHeap* _g1h; 3797 G1ParScanThreadStateSet* _per_thread_states; 3798 G1ScannerTasksQueueSet* _task_queues; 3799 TaskTerminator _terminator; 3800 uint _num_workers; 3801 3802 void evacuate_live_objects(G1ParScanThreadState* pss, 3803 uint worker_id, 3804 G1GCPhaseTimes::GCParPhases objcopy_phase, 3805 G1GCPhaseTimes::GCParPhases termination_phase) { 3806 G1GCPhaseTimes* p = _g1h->phase_times(); 3807 3808 Ticks start = Ticks::now(); 3809 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase); 3810 cl.do_void(); 3811 3812 assert(pss->queue_is_empty(), "should be empty"); 3813 3814 Tickspan evac_time = (Ticks::now() - start); 3815 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3816 3817 if (termination_phase == G1GCPhaseTimes::Termination) { 3818 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3819 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3820 } else { 3821 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3822 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3823 } 3824 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3825 } 3826 3827 virtual void start_work(uint worker_id) { } 3828 3829 virtual void end_work(uint worker_id) { } 3830 3831 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3832 3833 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3834 3835 public: 3836 G1EvacuateRegionsBaseTask(const char* name, 3837 G1ParScanThreadStateSet* per_thread_states, 3838 G1ScannerTasksQueueSet* task_queues, 3839 uint num_workers) : 3840 AbstractGangTask(name), 3841 _g1h(G1CollectedHeap::heap()), 3842 _per_thread_states(per_thread_states), 3843 _task_queues(task_queues), 3844 _terminator(num_workers, _task_queues), 3845 _num_workers(num_workers) 3846 { } 3847 3848 void work(uint worker_id) { 3849 start_work(worker_id); 3850 3851 { 3852 ResourceMark rm; 3853 HandleMark hm; 3854 3855 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3856 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3857 3858 scan_roots(pss, worker_id); 3859 evacuate_live_objects(pss, worker_id); 3860 } 3861 3862 end_work(worker_id); 3863 } 3864 }; 3865 3866 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3867 G1RootProcessor* _root_processor; 3868 3869 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3870 _root_processor->evacuate_roots(pss, worker_id); 3871 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3872 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3873 } 3874 3875 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3876 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3877 } 3878 3879 void start_work(uint worker_id) { 3880 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3881 } 3882 3883 void end_work(uint worker_id) { 3884 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3885 } 3886 3887 public: 3888 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3889 G1ParScanThreadStateSet* per_thread_states, 3890 G1ScannerTasksQueueSet* task_queues, 3891 G1RootProcessor* root_processor, 3892 uint num_workers) : 3893 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3894 _root_processor(root_processor) 3895 { } 3896 }; 3897 3898 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3899 G1GCPhaseTimes* p = phase_times(); 3900 3901 { 3902 Ticks start = Ticks::now(); 3903 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3904 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3905 } 3906 3907 Tickspan task_time; 3908 const uint num_workers = workers()->active_workers(); 3909 3910 Ticks start_processing = Ticks::now(); 3911 { 3912 G1RootProcessor root_processor(this, num_workers); 3913 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3914 task_time = run_task(&g1_par_task); 3915 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3916 // To extract its code root fixup time we measure total time of this scope and 3917 // subtract from the time the WorkGang task took. 3918 } 3919 Tickspan total_processing = Ticks::now() - start_processing; 3920 3921 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3922 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3923 } 3924 3925 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3926 3927 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3928 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3929 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3930 } 3931 3932 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3933 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3934 } 3935 3936 public: 3937 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3938 G1ScannerTasksQueueSet* queues, 3939 uint num_workers) : 3940 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3941 } 3942 }; 3943 3944 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3945 class G1MarkScope : public MarkScope { }; 3946 3947 Tickspan task_time; 3948 3949 Ticks start_processing = Ticks::now(); 3950 { 3951 G1MarkScope code_mark_scope; 3952 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3953 task_time = run_task(&task); 3954 // See comment in evacuate_collection_set() for the reason of the scope. 3955 } 3956 Tickspan total_processing = Ticks::now() - start_processing; 3957 3958 G1GCPhaseTimes* p = phase_times(); 3959 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3960 } 3961 3962 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3963 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3964 3965 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3966 3967 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3968 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3969 3970 if (time_left_ms < 0 || 3971 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3972 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3973 _collection_set.optional_region_length(), time_left_ms); 3974 break; 3975 } 3976 3977 { 3978 Ticks start = Ticks::now(); 3979 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3980 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3981 } 3982 3983 { 3984 Ticks start = Ticks::now(); 3985 evacuate_next_optional_regions(per_thread_states); 3986 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3987 } 3988 } 3989 3990 _collection_set.abandon_optional_collection_set(per_thread_states); 3991 } 3992 3993 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3994 G1RedirtyCardsQueueSet* rdcqs, 3995 G1ParScanThreadStateSet* per_thread_states) { 3996 G1GCPhaseTimes* p = phase_times(); 3997 3998 rem_set()->cleanup_after_scan_heap_roots(); 3999 4000 // Process any discovered reference objects - we have 4001 // to do this _before_ we retire the GC alloc regions 4002 // as we may have to copy some 'reachable' referent 4003 // objects (and their reachable sub-graphs) that were 4004 // not copied during the pause. 4005 process_discovered_references(per_thread_states); 4006 4007 G1STWIsAliveClosure is_alive(this); 4008 G1KeepAliveClosure keep_alive(this); 4009 4010 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times()); 4011 4012 if (G1StringDedup::is_enabled()) { 4013 double string_dedup_time_ms = os::elapsedTime(); 4014 4015 string_dedup_cleaning(&is_alive, &keep_alive, p); 4016 4017 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 4018 p->record_string_deduplication_time(string_cleanup_time_ms); 4019 } 4020 4021 _allocator->release_gc_alloc_regions(evacuation_info); 4022 4023 if (evacuation_failed()) { 4024 restore_after_evac_failure(rdcqs); 4025 4026 // Reset the G1EvacuationFailureALot counters and flags 4027 NOT_PRODUCT(reset_evacuation_should_fail();) 4028 4029 double recalculate_used_start = os::elapsedTime(); 4030 set_used(recalculate_used()); 4031 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 4032 4033 if (_archive_allocator != NULL) { 4034 _archive_allocator->clear_used(); 4035 } 4036 for (uint i = 0; i < ParallelGCThreads; i++) { 4037 if (_evacuation_failed_info_array[i].has_failed()) { 4038 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4039 } 4040 } 4041 } else { 4042 // The "used" of the the collection set have already been subtracted 4043 // when they were freed. Add in the bytes used. 4044 increase_used(_bytes_used_during_gc); 4045 } 4046 4047 _preserved_marks_set.assert_empty(); 4048 4049 merge_per_thread_state_info(per_thread_states); 4050 4051 // Reset and re-enable the hot card cache. 4052 // Note the counts for the cards in the regions in the 4053 // collection set are reset when the collection set is freed. 4054 _hot_card_cache->reset_hot_cache(); 4055 _hot_card_cache->set_use_cache(true); 4056 4057 purge_code_root_memory(); 4058 4059 redirty_logged_cards(rdcqs); 4060 4061 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4062 4063 eagerly_reclaim_humongous_regions(); 4064 4065 record_obj_copy_mem_stats(); 4066 4067 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4068 evacuation_info.set_bytes_used(_bytes_used_during_gc); 4069 4070 #if COMPILER2_OR_JVMCI 4071 double start = os::elapsedTime(); 4072 DerivedPointerTable::update_pointers(); 4073 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4074 #endif 4075 policy()->print_age_table(); 4076 } 4077 4078 void G1CollectedHeap::record_obj_copy_mem_stats() { 4079 policy()->old_gen_alloc_tracker()-> 4080 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4081 4082 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4083 create_g1_evac_summary(&_old_evac_stats)); 4084 } 4085 4086 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 4087 assert(!hr->is_free(), "the region should not be free"); 4088 assert(!hr->is_empty(), "the region should not be empty"); 4089 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4090 4091 if (G1VerifyBitmaps) { 4092 MemRegion mr(hr->bottom(), hr->end()); 4093 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4094 } 4095 4096 // Clear the card counts for this region. 4097 // Note: we only need to do this if the region is not young 4098 // (since we don't refine cards in young regions). 4099 if (!hr->is_young()) { 4100 _hot_card_cache->reset_card_counts(hr); 4101 } 4102 4103 // Reset region metadata to allow reuse. 4104 hr->hr_clear(true /* clear_space */); 4105 _policy->remset_tracker()->update_at_free(hr); 4106 4107 if (free_list != NULL) { 4108 free_list->add_ordered(hr); 4109 } 4110 } 4111 4112 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4113 FreeRegionList* free_list) { 4114 assert(hr->is_humongous(), "this is only for humongous regions"); 4115 assert(free_list != NULL, "pre-condition"); 4116 hr->clear_humongous(); 4117 free_region(hr, free_list); 4118 } 4119 4120 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4121 const uint humongous_regions_removed) { 4122 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4123 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4124 _old_set.bulk_remove(old_regions_removed); 4125 _humongous_set.bulk_remove(humongous_regions_removed); 4126 } 4127 4128 } 4129 4130 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4131 assert(list != NULL, "list can't be null"); 4132 if (!list->is_empty()) { 4133 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4134 _hrm->insert_list_into_free_list(list); 4135 } 4136 } 4137 4138 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4139 decrease_used(bytes); 4140 } 4141 4142 class G1FreeCollectionSetTask : public AbstractGangTask { 4143 // Helper class to keep statistics for the collection set freeing 4144 class FreeCSetStats { 4145 size_t _before_used_bytes; // Usage in regions successfully evacutate 4146 size_t _after_used_bytes; // Usage in regions failing evacuation 4147 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old 4148 size_t _failure_used_words; // Live size in failed regions 4149 size_t _failure_waste_words; // Wasted size in failed regions 4150 size_t _rs_length; // Remembered set size 4151 uint _regions_freed; // Number of regions freed 4152 public: 4153 FreeCSetStats() : 4154 _before_used_bytes(0), 4155 _after_used_bytes(0), 4156 _bytes_allocated_in_old_since_last_gc(0), 4157 _failure_used_words(0), 4158 _failure_waste_words(0), 4159 _rs_length(0), 4160 _regions_freed(0) { } 4161 4162 void merge_stats(FreeCSetStats* other) { 4163 assert(other != NULL, "invariant"); 4164 _before_used_bytes += other->_before_used_bytes; 4165 _after_used_bytes += other->_after_used_bytes; 4166 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc; 4167 _failure_used_words += other->_failure_used_words; 4168 _failure_waste_words += other->_failure_waste_words; 4169 _rs_length += other->_rs_length; 4170 _regions_freed += other->_regions_freed; 4171 } 4172 4173 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) { 4174 evacuation_info->set_regions_freed(_regions_freed); 4175 evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4176 4177 g1h->decrement_summary_bytes(_before_used_bytes); 4178 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4179 4180 G1Policy *policy = g1h->policy(); 4181 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4182 policy->record_rs_length(_rs_length); 4183 policy->cset_regions_freed(); 4184 } 4185 4186 void account_failed_region(HeapRegion* r) { 4187 size_t used_words = r->marked_bytes() / HeapWordSize; 4188 _failure_used_words += used_words; 4189 _failure_waste_words += HeapRegion::GrainWords - used_words; 4190 _after_used_bytes += r->used(); 4191 4192 // When moving a young gen region to old gen, we "allocate" that whole 4193 // region there. This is in addition to any already evacuated objects. 4194 // Notify the policy about that. Old gen regions do not cause an 4195 // additional allocation: both the objects still in the region and the 4196 // ones already moved are accounted for elsewhere. 4197 if (r->is_young()) { 4198 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4199 } 4200 } 4201 4202 void account_evacuated_region(HeapRegion* r) { 4203 _before_used_bytes += r->used(); 4204 _regions_freed += 1; 4205 } 4206 4207 void account_rs_length(HeapRegion* r) { 4208 _rs_length += r->rem_set()->occupied(); 4209 } 4210 }; 4211 4212 // Closure applied to all regions in the collection set. 4213 class FreeCSetClosure : public HeapRegionClosure { 4214 // Helper to send JFR events for regions. 4215 class JFREventForRegion { 4216 EventGCPhaseParallel _event; 4217 public: 4218 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() { 4219 _event.set_gcId(GCId::current()); 4220 _event.set_gcWorkerId(worker_id); 4221 if (region->is_young()) { 4222 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4223 } else { 4224 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4225 } 4226 } 4227 4228 ~JFREventForRegion() { 4229 _event.commit(); 4230 } 4231 }; 4232 4233 // Helper to do timing for region work. 4234 class TimerForRegion { 4235 Tickspan& _time; 4236 Ticks _start_time; 4237 public: 4238 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { } 4239 ~TimerForRegion() { 4240 _time += Ticks::now() - _start_time; 4241 } 4242 }; 4243 4244 // FreeCSetClosure members 4245 G1CollectedHeap* _g1h; 4246 const size_t* _surviving_young_words; 4247 uint _worker_id; 4248 Tickspan _young_time; 4249 Tickspan _non_young_time; 4250 FreeCSetStats* _stats; 4251 4252 void assert_in_cset(HeapRegion* r) { 4253 assert(r->young_index_in_cset() != 0 && 4254 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(), 4255 "Young index %u is wrong for region %u of type %s with %u young regions", 4256 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length()); 4257 } 4258 4259 void handle_evacuated_region(HeapRegion* r) { 4260 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4261 stats()->account_evacuated_region(r); 4262 4263 // Free the region and and its remembered set. 4264 _g1h->free_region(r, NULL); 4265 } 4266 4267 void handle_failed_region(HeapRegion* r) { 4268 // Do some allocation statistics accounting. Regions that failed evacuation 4269 // are always made old, so there is no need to update anything in the young 4270 // gen statistics, but we need to update old gen statistics. 4271 stats()->account_failed_region(r); 4272 4273 // Update the region state due to the failed evacuation. 4274 r->handle_evacuation_failure(); 4275 4276 // Add region to old set, need to hold lock. 4277 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4278 _g1h->old_set_add(r); 4279 } 4280 4281 Tickspan& timer_for_region(HeapRegion* r) { 4282 return r->is_young() ? _young_time : _non_young_time; 4283 } 4284 4285 FreeCSetStats* stats() { 4286 return _stats; 4287 } 4288 public: 4289 FreeCSetClosure(const size_t* surviving_young_words, 4290 uint worker_id, 4291 FreeCSetStats* stats) : 4292 HeapRegionClosure(), 4293 _g1h(G1CollectedHeap::heap()), 4294 _surviving_young_words(surviving_young_words), 4295 _worker_id(worker_id), 4296 _young_time(), 4297 _non_young_time(), 4298 _stats(stats) { } 4299 4300 virtual bool do_heap_region(HeapRegion* r) { 4301 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index()); 4302 JFREventForRegion event(r, _worker_id); 4303 TimerForRegion timer(timer_for_region(r)); 4304 4305 _g1h->clear_region_attr(r); 4306 stats()->account_rs_length(r); 4307 4308 if (r->is_young()) { 4309 assert_in_cset(r); 4310 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]); 4311 } 4312 4313 if (r->evacuation_failed()) { 4314 handle_failed_region(r); 4315 } else { 4316 handle_evacuated_region(r); 4317 } 4318 assert(!_g1h->is_on_master_free_list(r), "sanity"); 4319 4320 return false; 4321 } 4322 4323 void report_timing(Tickspan parallel_time) { 4324 G1GCPhaseTimes* pt = _g1h->phase_times(); 4325 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds()); 4326 if (_young_time.value() > 0) { 4327 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds()); 4328 } 4329 if (_non_young_time.value() > 0) { 4330 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds()); 4331 } 4332 } 4333 }; 4334 4335 // G1FreeCollectionSetTask members 4336 G1CollectedHeap* _g1h; 4337 G1EvacuationInfo* _evacuation_info; 4338 FreeCSetStats* _worker_stats; 4339 HeapRegionClaimer _claimer; 4340 const size_t* _surviving_young_words; 4341 uint _active_workers; 4342 4343 FreeCSetStats* worker_stats(uint worker) { 4344 return &_worker_stats[worker]; 4345 } 4346 4347 void report_statistics() { 4348 // Merge the accounting 4349 FreeCSetStats total_stats; 4350 for (uint worker = 0; worker < _active_workers; worker++) { 4351 total_stats.merge_stats(worker_stats(worker)); 4352 } 4353 total_stats.report(_g1h, _evacuation_info); 4354 } 4355 4356 public: 4357 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) : 4358 AbstractGangTask("G1 Free Collection Set"), 4359 _g1h(G1CollectedHeap::heap()), 4360 _evacuation_info(evacuation_info), 4361 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)), 4362 _claimer(active_workers), 4363 _surviving_young_words(surviving_young_words), 4364 _active_workers(active_workers) { 4365 for (uint worker = 0; worker < active_workers; worker++) { 4366 ::new (&_worker_stats[worker]) FreeCSetStats(); 4367 } 4368 } 4369 4370 ~G1FreeCollectionSetTask() { 4371 Ticks serial_time = Ticks::now(); 4372 report_statistics(); 4373 for (uint worker = 0; worker < _active_workers; worker++) { 4374 _worker_stats[worker].~FreeCSetStats(); 4375 } 4376 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats); 4377 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0); 4378 } 4379 4380 virtual void work(uint worker_id) { 4381 EventGCPhaseParallel event; 4382 Ticks start = Ticks::now(); 4383 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id)); 4384 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id); 4385 4386 // Report the total parallel time along with some more detailed metrics. 4387 cl.report_timing(Ticks::now() - start); 4388 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet)); 4389 } 4390 }; 4391 4392 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4393 _eden.clear(); 4394 4395 // The free collections set is split up in two tasks, the first 4396 // frees the collection set and records what regions are free, 4397 // and the second one rebuilds the free list. This proved to be 4398 // more efficient than adding a sorted list to another. 4399 4400 Ticks free_cset_start_time = Ticks::now(); 4401 { 4402 uint const num_cs_regions = _collection_set.region_length(); 4403 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers()); 4404 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers); 4405 4406 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)", 4407 cl.name(), num_workers, num_cs_regions, num_regions()); 4408 workers()->run_task(&cl, num_workers); 4409 } 4410 4411 Ticks free_cset_end_time = Ticks::now(); 4412 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0); 4413 4414 // Now rebuild the free region list. 4415 hrm()->rebuild_free_list(workers()); 4416 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0); 4417 4418 collection_set->clear(); 4419 } 4420 4421 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4422 private: 4423 FreeRegionList* _free_region_list; 4424 HeapRegionSet* _proxy_set; 4425 uint _humongous_objects_reclaimed; 4426 uint _humongous_regions_reclaimed; 4427 size_t _freed_bytes; 4428 public: 4429 4430 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4431 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4432 } 4433 4434 virtual bool do_heap_region(HeapRegion* r) { 4435 if (!r->is_starts_humongous()) { 4436 return false; 4437 } 4438 4439 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4440 4441 oop obj = (oop)r->bottom(); 4442 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4443 4444 // The following checks whether the humongous object is live are sufficient. 4445 // The main additional check (in addition to having a reference from the roots 4446 // or the young gen) is whether the humongous object has a remembered set entry. 4447 // 4448 // A humongous object cannot be live if there is no remembered set for it 4449 // because: 4450 // - there can be no references from within humongous starts regions referencing 4451 // the object because we never allocate other objects into them. 4452 // (I.e. there are no intra-region references that may be missed by the 4453 // remembered set) 4454 // - as soon there is a remembered set entry to the humongous starts region 4455 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4456 // until the end of a concurrent mark. 4457 // 4458 // It is not required to check whether the object has been found dead by marking 4459 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4460 // all objects allocated during that time are considered live. 4461 // SATB marking is even more conservative than the remembered set. 4462 // So if at this point in the collection there is no remembered set entry, 4463 // nobody has a reference to it. 4464 // At the start of collection we flush all refinement logs, and remembered sets 4465 // are completely up-to-date wrt to references to the humongous object. 4466 // 4467 // Other implementation considerations: 4468 // - never consider object arrays at this time because they would pose 4469 // considerable effort for cleaning up the the remembered sets. This is 4470 // required because stale remembered sets might reference locations that 4471 // are currently allocated into. 4472 uint region_idx = r->hrm_index(); 4473 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4474 !r->rem_set()->is_empty()) { 4475 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", 4476 region_idx, 4477 (size_t)obj->size() * HeapWordSize, 4478 p2i(r->bottom()), 4479 r->rem_set()->occupied(), 4480 r->rem_set()->strong_code_roots_list_length(), 4481 next_bitmap->is_marked(r->bottom()), 4482 g1h->is_humongous_reclaim_candidate(region_idx), 4483 obj->is_typeArray() 4484 ); 4485 return false; 4486 } 4487 4488 guarantee(obj->is_typeArray(), 4489 "Only eagerly reclaiming type arrays is supported, but the object " 4490 PTR_FORMAT " is not.", p2i(r->bottom())); 4491 4492 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", 4493 region_idx, 4494 (size_t)obj->size() * HeapWordSize, 4495 p2i(r->bottom()), 4496 r->rem_set()->occupied(), 4497 r->rem_set()->strong_code_roots_list_length(), 4498 next_bitmap->is_marked(r->bottom()), 4499 g1h->is_humongous_reclaim_candidate(region_idx), 4500 obj->is_typeArray() 4501 ); 4502 4503 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4504 cm->humongous_object_eagerly_reclaimed(r); 4505 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4506 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4507 region_idx, 4508 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4509 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4510 _humongous_objects_reclaimed++; 4511 do { 4512 HeapRegion* next = g1h->next_region_in_humongous(r); 4513 _freed_bytes += r->used(); 4514 r->set_containing_set(NULL); 4515 _humongous_regions_reclaimed++; 4516 g1h->free_humongous_region(r, _free_region_list); 4517 r = next; 4518 } while (r != NULL); 4519 4520 return false; 4521 } 4522 4523 uint humongous_objects_reclaimed() { 4524 return _humongous_objects_reclaimed; 4525 } 4526 4527 uint humongous_regions_reclaimed() { 4528 return _humongous_regions_reclaimed; 4529 } 4530 4531 size_t bytes_freed() const { 4532 return _freed_bytes; 4533 } 4534 }; 4535 4536 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4537 assert_at_safepoint_on_vm_thread(); 4538 4539 if (!G1EagerReclaimHumongousObjects || 4540 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4541 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4542 return; 4543 } 4544 4545 double start_time = os::elapsedTime(); 4546 4547 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4548 4549 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4550 heap_region_iterate(&cl); 4551 4552 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4553 4554 G1HRPrinter* hrp = hr_printer(); 4555 if (hrp->is_active()) { 4556 FreeRegionListIterator iter(&local_cleanup_list); 4557 while (iter.more_available()) { 4558 HeapRegion* hr = iter.get_next(); 4559 hrp->cleanup(hr); 4560 } 4561 } 4562 4563 prepend_to_freelist(&local_cleanup_list); 4564 decrement_summary_bytes(cl.bytes_freed()); 4565 4566 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4567 cl.humongous_objects_reclaimed()); 4568 } 4569 4570 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4571 public: 4572 virtual bool do_heap_region(HeapRegion* r) { 4573 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4574 G1CollectedHeap::heap()->clear_region_attr(r); 4575 r->clear_young_index_in_cset(); 4576 return false; 4577 } 4578 }; 4579 4580 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4581 G1AbandonCollectionSetClosure cl; 4582 collection_set_iterate_all(&cl); 4583 4584 collection_set->clear(); 4585 collection_set->stop_incremental_building(); 4586 } 4587 4588 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4589 return _allocator->is_retained_old_region(hr); 4590 } 4591 4592 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4593 _eden.add(hr); 4594 _policy->set_region_eden(hr); 4595 } 4596 4597 #ifdef ASSERT 4598 4599 class NoYoungRegionsClosure: public HeapRegionClosure { 4600 private: 4601 bool _success; 4602 public: 4603 NoYoungRegionsClosure() : _success(true) { } 4604 bool do_heap_region(HeapRegion* r) { 4605 if (r->is_young()) { 4606 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4607 p2i(r->bottom()), p2i(r->end())); 4608 _success = false; 4609 } 4610 return false; 4611 } 4612 bool success() { return _success; } 4613 }; 4614 4615 bool G1CollectedHeap::check_young_list_empty() { 4616 bool ret = (young_regions_count() == 0); 4617 4618 NoYoungRegionsClosure closure; 4619 heap_region_iterate(&closure); 4620 ret = ret && closure.success(); 4621 4622 return ret; 4623 } 4624 4625 #endif // ASSERT 4626 4627 class TearDownRegionSetsClosure : public HeapRegionClosure { 4628 HeapRegionSet *_old_set; 4629 4630 public: 4631 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4632 4633 bool do_heap_region(HeapRegion* r) { 4634 if (r->is_old()) { 4635 _old_set->remove(r); 4636 } else if(r->is_young()) { 4637 r->uninstall_surv_rate_group(); 4638 } else { 4639 // We ignore free regions, we'll empty the free list afterwards. 4640 // We ignore humongous and archive regions, we're not tearing down these 4641 // sets. 4642 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4643 "it cannot be another type"); 4644 } 4645 return false; 4646 } 4647 4648 ~TearDownRegionSetsClosure() { 4649 assert(_old_set->is_empty(), "post-condition"); 4650 } 4651 }; 4652 4653 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4654 assert_at_safepoint_on_vm_thread(); 4655 4656 if (!free_list_only) { 4657 TearDownRegionSetsClosure cl(&_old_set); 4658 heap_region_iterate(&cl); 4659 4660 // Note that emptying the _young_list is postponed and instead done as 4661 // the first step when rebuilding the regions sets again. The reason for 4662 // this is that during a full GC string deduplication needs to know if 4663 // a collected region was young or old when the full GC was initiated. 4664 } 4665 _hrm->remove_all_free_regions(); 4666 } 4667 4668 void G1CollectedHeap::increase_used(size_t bytes) { 4669 _summary_bytes_used += bytes; 4670 } 4671 4672 void G1CollectedHeap::decrease_used(size_t bytes) { 4673 assert(_summary_bytes_used >= bytes, 4674 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4675 _summary_bytes_used, bytes); 4676 _summary_bytes_used -= bytes; 4677 } 4678 4679 void G1CollectedHeap::set_used(size_t bytes) { 4680 _summary_bytes_used = bytes; 4681 } 4682 4683 class RebuildRegionSetsClosure : public HeapRegionClosure { 4684 private: 4685 bool _free_list_only; 4686 4687 HeapRegionSet* _old_set; 4688 HeapRegionManager* _hrm; 4689 4690 size_t _total_used; 4691 4692 public: 4693 RebuildRegionSetsClosure(bool free_list_only, 4694 HeapRegionSet* old_set, 4695 HeapRegionManager* hrm) : 4696 _free_list_only(free_list_only), 4697 _old_set(old_set), _hrm(hrm), _total_used(0) { 4698 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4699 if (!free_list_only) { 4700 assert(_old_set->is_empty(), "pre-condition"); 4701 } 4702 } 4703 4704 bool do_heap_region(HeapRegion* r) { 4705 if (r->is_empty()) { 4706 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4707 // Add free regions to the free list 4708 r->set_free(); 4709 _hrm->insert_into_free_list(r); 4710 } else if (!_free_list_only) { 4711 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4712 4713 if (r->is_archive() || r->is_humongous()) { 4714 // We ignore archive and humongous regions. We left these sets unchanged. 4715 } else { 4716 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4717 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4718 r->move_to_old(); 4719 _old_set->add(r); 4720 } 4721 _total_used += r->used(); 4722 } 4723 4724 return false; 4725 } 4726 4727 size_t total_used() { 4728 return _total_used; 4729 } 4730 }; 4731 4732 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4733 assert_at_safepoint_on_vm_thread(); 4734 4735 if (!free_list_only) { 4736 _eden.clear(); 4737 _survivor.clear(); 4738 } 4739 4740 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4741 heap_region_iterate(&cl); 4742 4743 if (!free_list_only) { 4744 set_used(cl.total_used()); 4745 if (_archive_allocator != NULL) { 4746 _archive_allocator->clear_used(); 4747 } 4748 } 4749 assert_used_and_recalculate_used_equal(this); 4750 } 4751 4752 // Methods for the mutator alloc region 4753 4754 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4755 bool force, 4756 uint node_index) { 4757 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4758 bool should_allocate = policy()->should_allocate_mutator_region(); 4759 if (force || should_allocate) { 4760 HeapRegion* new_alloc_region = new_region(word_size, 4761 HeapRegionType::Eden, 4762 false /* do_expand */, 4763 node_index); 4764 if (new_alloc_region != NULL) { 4765 set_region_short_lived_locked(new_alloc_region); 4766 _hr_printer.alloc(new_alloc_region, !should_allocate); 4767 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4768 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4769 return new_alloc_region; 4770 } 4771 } 4772 return NULL; 4773 } 4774 4775 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4776 size_t allocated_bytes) { 4777 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4778 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4779 4780 collection_set()->add_eden_region(alloc_region); 4781 increase_used(allocated_bytes); 4782 _eden.add_used_bytes(allocated_bytes); 4783 _hr_printer.retire(alloc_region); 4784 4785 // We update the eden sizes here, when the region is retired, 4786 // instead of when it's allocated, since this is the point that its 4787 // used space has been recorded in _summary_bytes_used. 4788 g1mm()->update_eden_size(); 4789 } 4790 4791 // Methods for the GC alloc regions 4792 4793 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4794 if (dest.is_old()) { 4795 return true; 4796 } else { 4797 return survivor_regions_count() < policy()->max_survivor_regions(); 4798 } 4799 } 4800 4801 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4802 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4803 4804 if (!has_more_regions(dest)) { 4805 return NULL; 4806 } 4807 4808 HeapRegionType type; 4809 if (dest.is_young()) { 4810 type = HeapRegionType::Survivor; 4811 } else { 4812 type = HeapRegionType::Old; 4813 } 4814 4815 HeapRegion* new_alloc_region = new_region(word_size, 4816 type, 4817 true /* do_expand */, 4818 node_index); 4819 4820 if (new_alloc_region != NULL) { 4821 if (type.is_survivor()) { 4822 new_alloc_region->set_survivor(); 4823 _survivor.add(new_alloc_region); 4824 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4825 } else { 4826 new_alloc_region->set_old(); 4827 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4828 } 4829 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4830 register_region_with_region_attr(new_alloc_region); 4831 _hr_printer.alloc(new_alloc_region); 4832 return new_alloc_region; 4833 } 4834 return NULL; 4835 } 4836 4837 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4838 size_t allocated_bytes, 4839 G1HeapRegionAttr dest) { 4840 _bytes_used_during_gc += allocated_bytes; 4841 if (dest.is_old()) { 4842 old_set_add(alloc_region); 4843 } else { 4844 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4845 _survivor.add_used_bytes(allocated_bytes); 4846 } 4847 4848 bool const during_im = collector_state()->in_initial_mark_gc(); 4849 if (during_im && allocated_bytes > 0) { 4850 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4851 } 4852 _hr_printer.retire(alloc_region); 4853 } 4854 4855 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4856 bool expanded = false; 4857 uint index = _hrm->find_highest_free(&expanded); 4858 4859 if (index != G1_NO_HRM_INDEX) { 4860 if (expanded) { 4861 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4862 HeapRegion::GrainWords * HeapWordSize); 4863 } 4864 return _hrm->allocate_free_regions_starting_at(index, 1); 4865 } 4866 return NULL; 4867 } 4868 4869 // Optimized nmethod scanning 4870 4871 class RegisterNMethodOopClosure: public OopClosure { 4872 G1CollectedHeap* _g1h; 4873 nmethod* _nm; 4874 4875 template <class T> void do_oop_work(T* p) { 4876 T heap_oop = RawAccess<>::oop_load(p); 4877 if (!CompressedOops::is_null(heap_oop)) { 4878 oop obj = CompressedOops::decode_not_null(heap_oop); 4879 HeapRegion* hr = _g1h->heap_region_containing(obj); 4880 assert(!hr->is_continues_humongous(), 4881 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4882 " starting at " HR_FORMAT, 4883 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4884 4885 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4886 hr->add_strong_code_root_locked(_nm); 4887 } 4888 } 4889 4890 public: 4891 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4892 _g1h(g1h), _nm(nm) {} 4893 4894 void do_oop(oop* p) { do_oop_work(p); } 4895 void do_oop(narrowOop* p) { do_oop_work(p); } 4896 }; 4897 4898 class UnregisterNMethodOopClosure: public OopClosure { 4899 G1CollectedHeap* _g1h; 4900 nmethod* _nm; 4901 4902 template <class T> void do_oop_work(T* p) { 4903 T heap_oop = RawAccess<>::oop_load(p); 4904 if (!CompressedOops::is_null(heap_oop)) { 4905 oop obj = CompressedOops::decode_not_null(heap_oop); 4906 HeapRegion* hr = _g1h->heap_region_containing(obj); 4907 assert(!hr->is_continues_humongous(), 4908 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4909 " starting at " HR_FORMAT, 4910 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4911 4912 hr->remove_strong_code_root(_nm); 4913 } 4914 } 4915 4916 public: 4917 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4918 _g1h(g1h), _nm(nm) {} 4919 4920 void do_oop(oop* p) { do_oop_work(p); } 4921 void do_oop(narrowOop* p) { do_oop_work(p); } 4922 }; 4923 4924 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4925 guarantee(nm != NULL, "sanity"); 4926 RegisterNMethodOopClosure reg_cl(this, nm); 4927 nm->oops_do(®_cl); 4928 } 4929 4930 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4931 guarantee(nm != NULL, "sanity"); 4932 UnregisterNMethodOopClosure reg_cl(this, nm); 4933 nm->oops_do(®_cl, true); 4934 } 4935 4936 void G1CollectedHeap::purge_code_root_memory() { 4937 double purge_start = os::elapsedTime(); 4938 G1CodeRootSet::purge(); 4939 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4940 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4941 } 4942 4943 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4944 G1CollectedHeap* _g1h; 4945 4946 public: 4947 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4948 _g1h(g1h) {} 4949 4950 void do_code_blob(CodeBlob* cb) { 4951 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4952 if (nm == NULL) { 4953 return; 4954 } 4955 4956 _g1h->register_nmethod(nm); 4957 } 4958 }; 4959 4960 void G1CollectedHeap::rebuild_strong_code_roots() { 4961 RebuildStrongCodeRootClosure blob_cl(this); 4962 CodeCache::blobs_do(&blob_cl); 4963 } 4964 4965 void G1CollectedHeap::initialize_serviceability() { 4966 _g1mm->initialize_serviceability(); 4967 } 4968 4969 MemoryUsage G1CollectedHeap::memory_usage() { 4970 return _g1mm->memory_usage(); 4971 } 4972 4973 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4974 return _g1mm->memory_managers(); 4975 } 4976 4977 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4978 return _g1mm->memory_pools(); 4979 }