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