1 /* 2 * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/g1Allocator.inline.hpp" 32 #include "gc/g1/g1Arguments.hpp" 33 #include "gc/g1/g1BarrierSet.hpp" 34 #include "gc/g1/g1CardTableEntryClosure.hpp" 35 #include "gc/g1/g1CollectedHeap.inline.hpp" 36 #include "gc/g1/g1CollectionSet.hpp" 37 #include "gc/g1/g1CollectorState.hpp" 38 #include "gc/g1/g1ConcurrentRefine.hpp" 39 #include "gc/g1/g1ConcurrentRefineThread.hpp" 40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 41 #include "gc/g1/g1DirtyCardQueue.hpp" 42 #include "gc/g1/g1EvacStats.inline.hpp" 43 #include "gc/g1/g1FullCollector.hpp" 44 #include "gc/g1/g1GCParPhaseTimesTracker.hpp" 45 #include "gc/g1/g1GCPhaseTimes.hpp" 46 #include "gc/g1/g1HeapSizingPolicy.hpp" 47 #include "gc/g1/g1HeapTransition.hpp" 48 #include "gc/g1/g1HeapVerifier.hpp" 49 #include "gc/g1/g1HotCardCache.hpp" 50 #include "gc/g1/g1InitLogger.hpp" 51 #include "gc/g1/g1MemoryPool.hpp" 52 #include "gc/g1/g1OopClosures.inline.hpp" 53 #include "gc/g1/g1ParallelCleaning.hpp" 54 #include "gc/g1/g1ParScanThreadState.inline.hpp" 55 #include "gc/g1/g1Policy.hpp" 56 #include "gc/g1/g1RedirtyCardsQueue.hpp" 57 #include "gc/g1/g1RegionToSpaceMapper.hpp" 58 #include "gc/g1/g1RemSet.hpp" 59 #include "gc/g1/g1RootClosures.hpp" 60 #include "gc/g1/g1RootProcessor.hpp" 61 #include "gc/g1/g1SATBMarkQueueSet.hpp" 62 #include "gc/g1/g1StringDedup.hpp" 63 #include "gc/g1/g1ThreadLocalData.hpp" 64 #include "gc/g1/g1Trace.hpp" 65 #include "gc/g1/g1YCTypes.hpp" 66 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 67 #include "gc/g1/g1VMOperations.hpp" 68 #include "gc/g1/heapRegion.inline.hpp" 69 #include "gc/g1/heapRegionRemSet.hpp" 70 #include "gc/g1/heapRegionSet.inline.hpp" 71 #include "gc/shared/concurrentGCBreakpoints.hpp" 72 #include "gc/shared/gcBehaviours.hpp" 73 #include "gc/shared/gcHeapSummary.hpp" 74 #include "gc/shared/gcId.hpp" 75 #include "gc/shared/gcLocker.hpp" 76 #include "gc/shared/gcTimer.hpp" 77 #include "gc/shared/gcTraceTime.inline.hpp" 78 #include "gc/shared/generationSpec.hpp" 79 #include "gc/shared/isGCActiveMark.hpp" 80 #include "gc/shared/locationPrinter.inline.hpp" 81 #include "gc/shared/oopStorageParState.hpp" 82 #include "gc/shared/preservedMarks.inline.hpp" 83 #include "gc/shared/suspendibleThreadSet.hpp" 84 #include "gc/shared/referenceProcessor.inline.hpp" 85 #include "gc/shared/taskTerminator.hpp" 86 #include "gc/shared/taskqueue.inline.hpp" 87 #include "gc/shared/weakProcessor.inline.hpp" 88 #include "gc/shared/workerPolicy.hpp" 89 #include "logging/log.hpp" 90 #include "memory/allocation.hpp" 91 #include "memory/iterator.hpp" 92 #include "memory/heapInspection.hpp" 93 #include "memory/resourceArea.hpp" 94 #include "memory/universe.hpp" 95 #include "oops/access.inline.hpp" 96 #include "oops/compressedOops.inline.hpp" 97 #include "oops/oop.inline.hpp" 98 #include "runtime/atomic.hpp" 99 #include "runtime/handles.inline.hpp" 100 #include "runtime/init.hpp" 101 #include "runtime/orderAccess.hpp" 102 #include "runtime/threadSMR.hpp" 103 #include "runtime/vmThread.hpp" 104 #include "utilities/align.hpp" 105 #include "utilities/autoRestore.hpp" 106 #include "utilities/bitMap.inline.hpp" 107 #include "utilities/globalDefinitions.hpp" 108 #include "utilities/stack.inline.hpp" 109 110 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 111 112 // INVARIANTS/NOTES 113 // 114 // All allocation activity covered by the G1CollectedHeap interface is 115 // serialized by acquiring the HeapLock. This happens in mem_allocate 116 // and allocate_new_tlab, which are the "entry" points to the 117 // allocation code from the rest of the JVM. (Note that this does not 118 // apply to TLAB allocation, which is not part of this interface: it 119 // is done by clients of this interface.) 120 121 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 122 private: 123 size_t _num_dirtied; 124 G1CollectedHeap* _g1h; 125 G1CardTable* _g1_ct; 126 127 HeapRegion* region_for_card(CardValue* card_ptr) const { 128 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 129 } 130 131 bool will_become_free(HeapRegion* hr) const { 132 // A region will be freed by free_collection_set if the region is in the 133 // collection set and has not had an evacuation failure. 134 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 135 } 136 137 public: 138 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 139 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 140 141 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 142 HeapRegion* hr = region_for_card(card_ptr); 143 144 // Should only dirty cards in regions that won't be freed. 145 if (!will_become_free(hr)) { 146 *card_ptr = G1CardTable::dirty_card_val(); 147 _num_dirtied++; 148 } 149 } 150 151 size_t num_dirtied() const { return _num_dirtied; } 152 }; 153 154 155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 156 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 157 } 158 159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 160 // The from card cache is not the memory that is actually committed. So we cannot 161 // take advantage of the zero_filled parameter. 162 reset_from_card_cache(start_idx, num_regions); 163 } 164 165 Tickspan G1CollectedHeap::run_task_timed(AbstractGangTask* task) { 166 Ticks start = Ticks::now(); 167 workers()->run_task(task); 168 return Ticks::now() - start; 169 } 170 171 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 172 MemRegion mr) { 173 return new HeapRegion(hrs_index, bot(), mr); 174 } 175 176 // Private methods. 177 178 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 179 HeapRegionType type, 180 bool do_expand, 181 uint node_index) { 182 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 183 "the only time we use this to allocate a humongous region is " 184 "when we are allocating a single humongous region"); 185 186 HeapRegion* res = _hrm->allocate_free_region(type, node_index); 187 188 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 189 // Currently, only attempts to allocate GC alloc regions set 190 // do_expand to true. So, we should only reach here during a 191 // safepoint. If this assumption changes we might have to 192 // reconsider the use of _expand_heap_after_alloc_failure. 193 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 194 195 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 196 word_size * HeapWordSize); 197 198 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 199 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 200 word_size * HeapWordSize); 201 if (expand_single_region(node_index)) { 202 // Given that expand_single_region() succeeded in expanding the heap, and we 203 // always expand the heap by an amount aligned to the heap 204 // region size, the free list should in theory not be empty. 205 // In either case allocate_free_region() will check for NULL. 206 res = _hrm->allocate_free_region(type, node_index); 207 } else { 208 _expand_heap_after_alloc_failure = false; 209 } 210 } 211 return res; 212 } 213 214 HeapWord* 215 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 216 uint num_regions, 217 size_t word_size) { 218 assert(first_hr != NULL, "pre-condition"); 219 assert(is_humongous(word_size), "word_size should be humongous"); 220 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 221 222 // Index of last region in the series. 223 uint first = first_hr->hrm_index(); 224 uint last = first + num_regions - 1; 225 226 // We need to initialize the region(s) we just discovered. This is 227 // a bit tricky given that it can happen concurrently with 228 // refinement threads refining cards on these regions and 229 // potentially wanting to refine the BOT as they are scanning 230 // those cards (this can happen shortly after a cleanup; see CR 231 // 6991377). So we have to set up the region(s) carefully and in 232 // a specific order. 233 234 // The word size sum of all the regions we will allocate. 235 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 236 assert(word_size <= word_size_sum, "sanity"); 237 238 // The passed in hr will be the "starts humongous" region. The header 239 // of the new object will be placed at the bottom of this region. 240 HeapWord* new_obj = first_hr->bottom(); 241 // This will be the new top of the new object. 242 HeapWord* obj_top = new_obj + word_size; 243 244 // First, we need to zero the header of the space that we will be 245 // allocating. When we update top further down, some refinement 246 // threads might try to scan the region. By zeroing the header we 247 // ensure that any thread that will try to scan the region will 248 // come across the zero klass word and bail out. 249 // 250 // NOTE: It would not have been correct to have used 251 // CollectedHeap::fill_with_object() and make the space look like 252 // an int array. The thread that is doing the allocation will 253 // later update the object header to a potentially different array 254 // type and, for a very short period of time, the klass and length 255 // fields will be inconsistent. This could cause a refinement 256 // thread to calculate the object size incorrectly. 257 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 258 259 // Next, pad out the unused tail of the last region with filler 260 // objects, for improved usage accounting. 261 // How many words we use for filler objects. 262 size_t word_fill_size = word_size_sum - word_size; 263 264 // How many words memory we "waste" which cannot hold a filler object. 265 size_t words_not_fillable = 0; 266 267 if (word_fill_size >= min_fill_size()) { 268 fill_with_objects(obj_top, word_fill_size); 269 } else if (word_fill_size > 0) { 270 // We have space to fill, but we cannot fit an object there. 271 words_not_fillable = word_fill_size; 272 word_fill_size = 0; 273 } 274 275 // We will set up the first region as "starts humongous". This 276 // will also update the BOT covering all the regions to reflect 277 // that there is a single object that starts at the bottom of the 278 // first region. 279 first_hr->set_starts_humongous(obj_top, word_fill_size); 280 _policy->remset_tracker()->update_at_allocate(first_hr); 281 // Then, if there are any, we will set up the "continues 282 // humongous" regions. 283 HeapRegion* hr = NULL; 284 for (uint i = first + 1; i <= last; ++i) { 285 hr = region_at(i); 286 hr->set_continues_humongous(first_hr); 287 _policy->remset_tracker()->update_at_allocate(hr); 288 } 289 290 // Up to this point no concurrent thread would have been able to 291 // do any scanning on any region in this series. All the top 292 // fields still point to bottom, so the intersection between 293 // [bottom,top] and [card_start,card_end] will be empty. Before we 294 // update the top fields, we'll do a storestore to make sure that 295 // no thread sees the update to top before the zeroing of the 296 // object header and the BOT initialization. 297 OrderAccess::storestore(); 298 299 // Now, we will update the top fields of the "continues humongous" 300 // regions except the last one. 301 for (uint i = first; i < last; ++i) { 302 hr = region_at(i); 303 hr->set_top(hr->end()); 304 } 305 306 hr = region_at(last); 307 // If we cannot fit a filler object, we must set top to the end 308 // of the humongous object, otherwise we cannot iterate the heap 309 // and the BOT will not be complete. 310 hr->set_top(hr->end() - words_not_fillable); 311 312 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 313 "obj_top should be in last region"); 314 315 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 316 317 assert(words_not_fillable == 0 || 318 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 319 "Miscalculation in humongous allocation"); 320 321 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 322 323 for (uint i = first; i <= last; ++i) { 324 hr = region_at(i); 325 _humongous_set.add(hr); 326 _hr_printer.alloc(hr); 327 } 328 329 return new_obj; 330 } 331 332 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 333 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 334 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 335 } 336 337 // If could fit into free regions w/o expansion, try. 338 // Otherwise, if can expand, do so. 339 // Otherwise, if using ex regions might help, try with ex given back. 340 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 341 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 342 343 _verifier->verify_region_sets_optional(); 344 345 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 346 347 // Policy: First try to allocate a humongous object in the free list. 348 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions); 349 if (humongous_start == NULL) { 350 // Policy: We could not find enough regions for the humongous object in the 351 // free list. Look through the heap to find a mix of free and uncommitted regions. 352 // If so, expand the heap and allocate the humongous object. 353 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions); 354 if (humongous_start != NULL) { 355 // We managed to find a region by expanding the heap. 356 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B", 357 word_size * HeapWordSize); 358 policy()->record_new_heap_size(num_regions()); 359 } else { 360 // Policy: Potentially trigger a defragmentation GC. 361 } 362 } 363 364 HeapWord* result = NULL; 365 if (humongous_start != NULL) { 366 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size); 367 assert(result != NULL, "it should always return a valid result"); 368 369 // A successful humongous object allocation changes the used space 370 // information of the old generation so we need to recalculate the 371 // sizes and update the jstat counters here. 372 g1mm()->update_sizes(); 373 } 374 375 _verifier->verify_region_sets_optional(); 376 377 return result; 378 } 379 380 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 381 size_t requested_size, 382 size_t* actual_size) { 383 assert_heap_not_locked_and_not_at_safepoint(); 384 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 385 386 return attempt_allocation(min_size, requested_size, actual_size); 387 } 388 389 HeapWord* 390 G1CollectedHeap::mem_allocate(size_t word_size, 391 bool* gc_overhead_limit_was_exceeded) { 392 assert_heap_not_locked_and_not_at_safepoint(); 393 394 if (is_humongous(word_size)) { 395 return attempt_allocation_humongous(word_size); 396 } 397 size_t dummy = 0; 398 return attempt_allocation(word_size, word_size, &dummy); 399 } 400 401 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 402 ResourceMark rm; // For retrieving the thread names in log messages. 403 404 // Make sure you read the note in attempt_allocation_humongous(). 405 406 assert_heap_not_locked_and_not_at_safepoint(); 407 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 408 "be called for humongous allocation requests"); 409 410 // We should only get here after the first-level allocation attempt 411 // (attempt_allocation()) failed to allocate. 412 413 // We will loop until a) we manage to successfully perform the 414 // allocation or b) we successfully schedule a collection which 415 // fails to perform the allocation. b) is the only case when we'll 416 // return NULL. 417 HeapWord* result = NULL; 418 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 419 bool should_try_gc; 420 uint gc_count_before; 421 422 { 423 MutexLocker x(Heap_lock); 424 result = _allocator->attempt_allocation_locked(word_size); 425 if (result != NULL) { 426 return result; 427 } 428 429 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 430 // This is different to when only GCLocker::needs_gc() is set: try to avoid 431 // waiting because the GCLocker is active to not wait too long. 432 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 433 // No need for an ergo message here, can_expand_young_list() does this when 434 // it returns true. 435 result = _allocator->attempt_allocation_force(word_size); 436 if (result != NULL) { 437 return result; 438 } 439 } 440 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 441 // the GCLocker initiated GC has been performed and then retry. This includes 442 // the case when the GC Locker is not active but has not been performed. 443 should_try_gc = !GCLocker::needs_gc(); 444 // Read the GC count while still holding the Heap_lock. 445 gc_count_before = total_collections(); 446 } 447 448 if (should_try_gc) { 449 bool succeeded; 450 result = do_collection_pause(word_size, gc_count_before, &succeeded, 451 GCCause::_g1_inc_collection_pause); 452 if (result != NULL) { 453 assert(succeeded, "only way to get back a non-NULL result"); 454 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 455 Thread::current()->name(), p2i(result)); 456 return result; 457 } 458 459 if (succeeded) { 460 // We successfully scheduled a collection which failed to allocate. No 461 // point in trying to allocate further. We'll just return NULL. 462 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 463 SIZE_FORMAT " words", Thread::current()->name(), word_size); 464 return NULL; 465 } 466 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 467 Thread::current()->name(), word_size); 468 } else { 469 // Failed to schedule a collection. 470 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 471 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 472 SIZE_FORMAT " words", Thread::current()->name(), word_size); 473 return NULL; 474 } 475 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 476 // The GCLocker is either active or the GCLocker initiated 477 // GC has not yet been performed. Stall until it is and 478 // then retry the allocation. 479 GCLocker::stall_until_clear(); 480 gclocker_retry_count += 1; 481 } 482 483 // We can reach here if we were unsuccessful in scheduling a 484 // collection (because another thread beat us to it) or if we were 485 // stalled due to the GC locker. In either can we should retry the 486 // allocation attempt in case another thread successfully 487 // performed a collection and reclaimed enough space. We do the 488 // first attempt (without holding the Heap_lock) here and the 489 // follow-on attempt will be at the start of the next loop 490 // iteration (after taking the Heap_lock). 491 size_t dummy = 0; 492 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 493 if (result != NULL) { 494 return result; 495 } 496 497 // Give a warning if we seem to be looping forever. 498 if ((QueuedAllocationWarningCount > 0) && 499 (try_count % QueuedAllocationWarningCount == 0)) { 500 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 501 Thread::current()->name(), try_count, word_size); 502 } 503 } 504 505 ShouldNotReachHere(); 506 return NULL; 507 } 508 509 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 510 assert_at_safepoint_on_vm_thread(); 511 if (_archive_allocator == NULL) { 512 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 513 } 514 } 515 516 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 517 // Allocations in archive regions cannot be of a size that would be considered 518 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 519 // may be different at archive-restore time. 520 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 521 } 522 523 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 524 assert_at_safepoint_on_vm_thread(); 525 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 526 if (is_archive_alloc_too_large(word_size)) { 527 return NULL; 528 } 529 return _archive_allocator->archive_mem_allocate(word_size); 530 } 531 532 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 533 size_t end_alignment_in_bytes) { 534 assert_at_safepoint_on_vm_thread(); 535 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 536 537 // Call complete_archive to do the real work, filling in the MemRegion 538 // array with the archive regions. 539 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 540 delete _archive_allocator; 541 _archive_allocator = NULL; 542 } 543 544 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 545 assert(ranges != NULL, "MemRegion array NULL"); 546 assert(count != 0, "No MemRegions provided"); 547 MemRegion reserved = _hrm->reserved(); 548 for (size_t i = 0; i < count; i++) { 549 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 550 return false; 551 } 552 } 553 return true; 554 } 555 556 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 557 size_t count, 558 bool open) { 559 assert(!is_init_completed(), "Expect to be called at JVM init time"); 560 assert(ranges != NULL, "MemRegion array NULL"); 561 assert(count != 0, "No MemRegions provided"); 562 MutexLocker x(Heap_lock); 563 564 MemRegion reserved = _hrm->reserved(); 565 HeapWord* prev_last_addr = NULL; 566 HeapRegion* prev_last_region = NULL; 567 568 // Temporarily disable pretouching of heap pages. This interface is used 569 // when mmap'ing archived heap data in, so pre-touching is wasted. 570 FlagSetting fs(AlwaysPreTouch, false); 571 572 // Enable archive object checking used by G1MarkSweep. We have to let it know 573 // about each archive range, so that objects in those ranges aren't marked. 574 G1ArchiveAllocator::enable_archive_object_check(); 575 576 // For each specified MemRegion range, allocate the corresponding G1 577 // regions and mark them as archive regions. We expect the ranges 578 // in ascending starting address order, without overlap. 579 for (size_t i = 0; i < count; i++) { 580 MemRegion curr_range = ranges[i]; 581 HeapWord* start_address = curr_range.start(); 582 size_t word_size = curr_range.word_size(); 583 HeapWord* last_address = curr_range.last(); 584 size_t commits = 0; 585 586 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 587 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 588 p2i(start_address), p2i(last_address)); 589 guarantee(start_address > prev_last_addr, 590 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 591 p2i(start_address), p2i(prev_last_addr)); 592 prev_last_addr = last_address; 593 594 // Check for ranges that start in the same G1 region in which the previous 595 // range ended, and adjust the start address so we don't try to allocate 596 // the same region again. If the current range is entirely within that 597 // region, skip it, just adjusting the recorded top. 598 HeapRegion* start_region = _hrm->addr_to_region(start_address); 599 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 600 start_address = start_region->end(); 601 if (start_address > last_address) { 602 increase_used(word_size * HeapWordSize); 603 start_region->set_top(last_address + 1); 604 continue; 605 } 606 start_region->set_top(start_address); 607 curr_range = MemRegion(start_address, last_address + 1); 608 start_region = _hrm->addr_to_region(start_address); 609 } 610 611 // Perform the actual region allocation, exiting if it fails. 612 // Then note how much new space we have allocated. 613 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 614 return false; 615 } 616 increase_used(word_size * HeapWordSize); 617 if (commits != 0) { 618 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 619 HeapRegion::GrainWords * HeapWordSize * commits); 620 621 } 622 623 // Mark each G1 region touched by the range as archive, add it to 624 // the old set, and set top. 625 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 626 HeapRegion* last_region = _hrm->addr_to_region(last_address); 627 prev_last_region = last_region; 628 629 while (curr_region != NULL) { 630 assert(curr_region->is_empty() && !curr_region->is_pinned(), 631 "Region already in use (index %u)", curr_region->hrm_index()); 632 if (open) { 633 curr_region->set_open_archive(); 634 } else { 635 curr_region->set_closed_archive(); 636 } 637 _hr_printer.alloc(curr_region); 638 _archive_set.add(curr_region); 639 HeapWord* top; 640 HeapRegion* next_region; 641 if (curr_region != last_region) { 642 top = curr_region->end(); 643 next_region = _hrm->next_region_in_heap(curr_region); 644 } else { 645 top = last_address + 1; 646 next_region = NULL; 647 } 648 curr_region->set_top(top); 649 curr_region = next_region; 650 } 651 652 // Notify mark-sweep of the archive 653 G1ArchiveAllocator::set_range_archive(curr_range, open); 654 } 655 return true; 656 } 657 658 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 659 assert(!is_init_completed(), "Expect to be called at JVM init time"); 660 assert(ranges != NULL, "MemRegion array NULL"); 661 assert(count != 0, "No MemRegions provided"); 662 MemRegion reserved = _hrm->reserved(); 663 HeapWord *prev_last_addr = NULL; 664 HeapRegion* prev_last_region = NULL; 665 666 // For each MemRegion, create filler objects, if needed, in the G1 regions 667 // that contain the address range. The address range actually within the 668 // MemRegion will not be modified. That is assumed to have been initialized 669 // elsewhere, probably via an mmap of archived heap data. 670 MutexLocker x(Heap_lock); 671 for (size_t i = 0; i < count; i++) { 672 HeapWord* start_address = ranges[i].start(); 673 HeapWord* last_address = ranges[i].last(); 674 675 assert(reserved.contains(start_address) && reserved.contains(last_address), 676 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 677 p2i(start_address), p2i(last_address)); 678 assert(start_address > prev_last_addr, 679 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 680 p2i(start_address), p2i(prev_last_addr)); 681 682 HeapRegion* start_region = _hrm->addr_to_region(start_address); 683 HeapRegion* last_region = _hrm->addr_to_region(last_address); 684 HeapWord* bottom_address = start_region->bottom(); 685 686 // Check for a range beginning in the same region in which the 687 // previous one ended. 688 if (start_region == prev_last_region) { 689 bottom_address = prev_last_addr + 1; 690 } 691 692 // Verify that the regions were all marked as archive regions by 693 // alloc_archive_regions. 694 HeapRegion* curr_region = start_region; 695 while (curr_region != NULL) { 696 guarantee(curr_region->is_archive(), 697 "Expected archive region at index %u", curr_region->hrm_index()); 698 if (curr_region != last_region) { 699 curr_region = _hrm->next_region_in_heap(curr_region); 700 } else { 701 curr_region = NULL; 702 } 703 } 704 705 prev_last_addr = last_address; 706 prev_last_region = last_region; 707 708 // Fill the memory below the allocated range with dummy object(s), 709 // if the region bottom does not match the range start, or if the previous 710 // range ended within the same G1 region, and there is a gap. 711 if (start_address != bottom_address) { 712 size_t fill_size = pointer_delta(start_address, bottom_address); 713 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 714 increase_used(fill_size * HeapWordSize); 715 } 716 } 717 } 718 719 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 720 size_t desired_word_size, 721 size_t* actual_word_size) { 722 assert_heap_not_locked_and_not_at_safepoint(); 723 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 724 "be called for humongous allocation requests"); 725 726 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 727 728 if (result == NULL) { 729 *actual_word_size = desired_word_size; 730 result = attempt_allocation_slow(desired_word_size); 731 } 732 733 assert_heap_not_locked(); 734 if (result != NULL) { 735 assert(*actual_word_size != 0, "Actual size must have been set here"); 736 dirty_young_block(result, *actual_word_size); 737 } else { 738 *actual_word_size = 0; 739 } 740 741 return result; 742 } 743 744 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 745 assert(!is_init_completed(), "Expect to be called at JVM init time"); 746 assert(ranges != NULL, "MemRegion array NULL"); 747 assert(count != 0, "No MemRegions provided"); 748 MemRegion reserved = _hrm->reserved(); 749 HeapWord* prev_last_addr = NULL; 750 HeapRegion* prev_last_region = NULL; 751 size_t size_used = 0; 752 size_t uncommitted_regions = 0; 753 754 // For each Memregion, free the G1 regions that constitute it, and 755 // notify mark-sweep that the range is no longer to be considered 'archive.' 756 MutexLocker x(Heap_lock); 757 for (size_t i = 0; i < count; i++) { 758 HeapWord* start_address = ranges[i].start(); 759 HeapWord* last_address = ranges[i].last(); 760 761 assert(reserved.contains(start_address) && reserved.contains(last_address), 762 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 763 p2i(start_address), p2i(last_address)); 764 assert(start_address > prev_last_addr, 765 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 766 p2i(start_address), p2i(prev_last_addr)); 767 size_used += ranges[i].byte_size(); 768 prev_last_addr = last_address; 769 770 HeapRegion* start_region = _hrm->addr_to_region(start_address); 771 HeapRegion* last_region = _hrm->addr_to_region(last_address); 772 773 // Check for ranges that start in the same G1 region in which the previous 774 // range ended, and adjust the start address so we don't try to free 775 // the same region again. If the current range is entirely within that 776 // region, skip it. 777 if (start_region == prev_last_region) { 778 start_address = start_region->end(); 779 if (start_address > last_address) { 780 continue; 781 } 782 start_region = _hrm->addr_to_region(start_address); 783 } 784 prev_last_region = last_region; 785 786 // After verifying that each region was marked as an archive region by 787 // alloc_archive_regions, set it free and empty and uncommit it. 788 HeapRegion* curr_region = start_region; 789 while (curr_region != NULL) { 790 guarantee(curr_region->is_archive(), 791 "Expected archive region at index %u", curr_region->hrm_index()); 792 uint curr_index = curr_region->hrm_index(); 793 _archive_set.remove(curr_region); 794 curr_region->set_free(); 795 curr_region->set_top(curr_region->bottom()); 796 if (curr_region != last_region) { 797 curr_region = _hrm->next_region_in_heap(curr_region); 798 } else { 799 curr_region = NULL; 800 } 801 _hrm->shrink_at(curr_index, 1); 802 uncommitted_regions++; 803 } 804 805 // Notify mark-sweep that this is no longer an archive range. 806 G1ArchiveAllocator::clear_range_archive(ranges[i]); 807 } 808 809 if (uncommitted_regions != 0) { 810 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 811 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 812 } 813 decrease_used(size_used); 814 } 815 816 oop G1CollectedHeap::materialize_archived_object(oop obj) { 817 assert(obj != NULL, "archived obj is NULL"); 818 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 819 820 // Loading an archived object makes it strongly reachable. If it is 821 // loaded during concurrent marking, it must be enqueued to the SATB 822 // queue, shading the previously white object gray. 823 G1BarrierSet::enqueue(obj); 824 825 return obj; 826 } 827 828 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 829 ResourceMark rm; // For retrieving the thread names in log messages. 830 831 // The structure of this method has a lot of similarities to 832 // attempt_allocation_slow(). The reason these two were not merged 833 // into a single one is that such a method would require several "if 834 // allocation is not humongous do this, otherwise do that" 835 // conditional paths which would obscure its flow. In fact, an early 836 // version of this code did use a unified method which was harder to 837 // follow and, as a result, it had subtle bugs that were hard to 838 // track down. So keeping these two methods separate allows each to 839 // be more readable. It will be good to keep these two in sync as 840 // much as possible. 841 842 assert_heap_not_locked_and_not_at_safepoint(); 843 assert(is_humongous(word_size), "attempt_allocation_humongous() " 844 "should only be called for humongous allocations"); 845 846 // Humongous objects can exhaust the heap quickly, so we should check if we 847 // need to start a marking cycle at each humongous object allocation. We do 848 // the check before we do the actual allocation. The reason for doing it 849 // before the allocation is that we avoid having to keep track of the newly 850 // allocated memory while we do a GC. 851 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 852 word_size)) { 853 collect(GCCause::_g1_humongous_allocation); 854 } 855 856 // We will loop until a) we manage to successfully perform the 857 // allocation or b) we successfully schedule a collection which 858 // fails to perform the allocation. b) is the only case when we'll 859 // return NULL. 860 HeapWord* result = NULL; 861 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 862 bool should_try_gc; 863 uint gc_count_before; 864 865 866 { 867 MutexLocker x(Heap_lock); 868 869 // Given that humongous objects are not allocated in young 870 // regions, we'll first try to do the allocation without doing a 871 // collection hoping that there's enough space in the heap. 872 result = humongous_obj_allocate(word_size); 873 if (result != NULL) { 874 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 875 policy()->old_gen_alloc_tracker()-> 876 add_allocated_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 877 return result; 878 } 879 880 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 881 // the GCLocker initiated GC has been performed and then retry. This includes 882 // the case when the GC Locker is not active but has not been performed. 883 should_try_gc = !GCLocker::needs_gc(); 884 // Read the GC count while still holding the Heap_lock. 885 gc_count_before = total_collections(); 886 } 887 888 if (should_try_gc) { 889 bool succeeded; 890 result = do_collection_pause(word_size, gc_count_before, &succeeded, 891 GCCause::_g1_humongous_allocation); 892 if (result != NULL) { 893 assert(succeeded, "only way to get back a non-NULL result"); 894 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 895 Thread::current()->name(), p2i(result)); 896 return result; 897 } 898 899 if (succeeded) { 900 // We successfully scheduled a collection which failed to allocate. No 901 // point in trying to allocate further. We'll just return NULL. 902 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 903 SIZE_FORMAT " words", Thread::current()->name(), word_size); 904 return NULL; 905 } 906 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 907 Thread::current()->name(), word_size); 908 } else { 909 // Failed to schedule a collection. 910 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 911 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 912 SIZE_FORMAT " words", Thread::current()->name(), word_size); 913 return NULL; 914 } 915 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 916 // The GCLocker is either active or the GCLocker initiated 917 // GC has not yet been performed. Stall until it is and 918 // then retry the allocation. 919 GCLocker::stall_until_clear(); 920 gclocker_retry_count += 1; 921 } 922 923 924 // We can reach here if we were unsuccessful in scheduling a 925 // collection (because another thread beat us to it) or if we were 926 // stalled due to the GC locker. In either can we should retry the 927 // allocation attempt in case another thread successfully 928 // performed a collection and reclaimed enough space. 929 // Humongous object allocation always needs a lock, so we wait for the retry 930 // in the next iteration of the loop, unlike for the regular iteration case. 931 // Give a warning if we seem to be looping forever. 932 933 if ((QueuedAllocationWarningCount > 0) && 934 (try_count % QueuedAllocationWarningCount == 0)) { 935 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 936 Thread::current()->name(), try_count, word_size); 937 } 938 } 939 940 ShouldNotReachHere(); 941 return NULL; 942 } 943 944 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 945 bool expect_null_mutator_alloc_region) { 946 assert_at_safepoint_on_vm_thread(); 947 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 948 "the current alloc region was unexpectedly found to be non-NULL"); 949 950 if (!is_humongous(word_size)) { 951 return _allocator->attempt_allocation_locked(word_size); 952 } else { 953 HeapWord* result = humongous_obj_allocate(word_size); 954 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 955 collector_state()->set_initiate_conc_mark_if_possible(true); 956 } 957 return result; 958 } 959 960 ShouldNotReachHere(); 961 } 962 963 class PostCompactionPrinterClosure: public HeapRegionClosure { 964 private: 965 G1HRPrinter* _hr_printer; 966 public: 967 bool do_heap_region(HeapRegion* hr) { 968 assert(!hr->is_young(), "not expecting to find young regions"); 969 _hr_printer->post_compaction(hr); 970 return false; 971 } 972 973 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 974 : _hr_printer(hr_printer) { } 975 }; 976 977 void G1CollectedHeap::print_hrm_post_compaction() { 978 if (_hr_printer.is_active()) { 979 PostCompactionPrinterClosure cl(hr_printer()); 980 heap_region_iterate(&cl); 981 } 982 } 983 984 void G1CollectedHeap::abort_concurrent_cycle() { 985 // If we start the compaction before the CM threads finish 986 // scanning the root regions we might trip them over as we'll 987 // be moving objects / updating references. So let's wait until 988 // they are done. By telling them to abort, they should complete 989 // early. 990 _cm->root_regions()->abort(); 991 _cm->root_regions()->wait_until_scan_finished(); 992 993 // Disable discovery and empty the discovered lists 994 // for the CM ref processor. 995 _ref_processor_cm->disable_discovery(); 996 _ref_processor_cm->abandon_partial_discovery(); 997 _ref_processor_cm->verify_no_references_recorded(); 998 999 // Abandon current iterations of concurrent marking and concurrent 1000 // refinement, if any are in progress. 1001 concurrent_mark()->concurrent_cycle_abort(); 1002 } 1003 1004 void G1CollectedHeap::prepare_heap_for_full_collection() { 1005 // Make sure we'll choose a new allocation region afterwards. 1006 _allocator->release_mutator_alloc_regions(); 1007 _allocator->abandon_gc_alloc_regions(); 1008 1009 // We may have added regions to the current incremental collection 1010 // set between the last GC or pause and now. We need to clear the 1011 // incremental collection set and then start rebuilding it afresh 1012 // after this full GC. 1013 abandon_collection_set(collection_set()); 1014 1015 tear_down_region_sets(false /* free_list_only */); 1016 1017 hrm()->prepare_for_full_collection_start(); 1018 } 1019 1020 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1021 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1022 assert_used_and_recalculate_used_equal(this); 1023 _verifier->verify_region_sets_optional(); 1024 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1025 _verifier->check_bitmaps("Full GC Start"); 1026 } 1027 1028 void G1CollectedHeap::prepare_heap_for_mutators() { 1029 hrm()->prepare_for_full_collection_end(); 1030 1031 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1032 ClassLoaderDataGraph::purge(); 1033 MetaspaceUtils::verify_metrics(); 1034 1035 // Prepare heap for normal collections. 1036 assert(num_free_regions() == 0, "we should not have added any free regions"); 1037 rebuild_region_sets(false /* free_list_only */); 1038 abort_refinement(); 1039 resize_heap_if_necessary(); 1040 1041 // Rebuild the strong code root lists for each region 1042 rebuild_strong_code_roots(); 1043 1044 // Purge code root memory 1045 purge_code_root_memory(); 1046 1047 // Start a new incremental collection set for the next pause 1048 start_new_collection_set(); 1049 1050 _allocator->init_mutator_alloc_regions(); 1051 1052 // Post collection state updates. 1053 MetaspaceGC::compute_new_size(); 1054 } 1055 1056 void G1CollectedHeap::abort_refinement() { 1057 if (_hot_card_cache->use_cache()) { 1058 _hot_card_cache->reset_hot_cache(); 1059 } 1060 1061 // Discard all remembered set updates and reset refinement statistics. 1062 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1063 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1064 "DCQS should be empty"); 1065 concurrent_refine()->get_and_reset_refinement_stats(); 1066 } 1067 1068 void G1CollectedHeap::verify_after_full_collection() { 1069 _hrm->verify_optional(); 1070 _verifier->verify_region_sets_optional(); 1071 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1072 // Clear the previous marking bitmap, if needed for bitmap verification. 1073 // Note we cannot do this when we clear the next marking bitmap in 1074 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1075 // objects marked during a full GC against the previous bitmap. 1076 // But we need to clear it before calling check_bitmaps below since 1077 // the full GC has compacted objects and updated TAMS but not updated 1078 // the prev bitmap. 1079 if (G1VerifyBitmaps) { 1080 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1081 _cm->clear_prev_bitmap(workers()); 1082 } 1083 // This call implicitly verifies that the next bitmap is clear after Full GC. 1084 _verifier->check_bitmaps("Full GC End"); 1085 1086 // At this point there should be no regions in the 1087 // entire heap tagged as young. 1088 assert(check_young_list_empty(), "young list should be empty at this point"); 1089 1090 // Note: since we've just done a full GC, concurrent 1091 // marking is no longer active. Therefore we need not 1092 // re-enable reference discovery for the CM ref processor. 1093 // That will be done at the start of the next marking cycle. 1094 // We also know that the STW processor should no longer 1095 // discover any new references. 1096 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1097 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1098 _ref_processor_stw->verify_no_references_recorded(); 1099 _ref_processor_cm->verify_no_references_recorded(); 1100 } 1101 1102 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1103 // Post collection logging. 1104 // We should do this after we potentially resize the heap so 1105 // that all the COMMIT / UNCOMMIT events are generated before 1106 // the compaction events. 1107 print_hrm_post_compaction(); 1108 heap_transition->print(); 1109 print_heap_after_gc(); 1110 print_heap_regions(); 1111 } 1112 1113 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1114 bool clear_all_soft_refs) { 1115 assert_at_safepoint_on_vm_thread(); 1116 1117 if (GCLocker::check_active_before_gc()) { 1118 // Full GC was not completed. 1119 return false; 1120 } 1121 1122 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1123 soft_ref_policy()->should_clear_all_soft_refs(); 1124 1125 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1126 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1127 1128 collector.prepare_collection(); 1129 collector.collect(); 1130 collector.complete_collection(); 1131 1132 // Full collection was successfully completed. 1133 return true; 1134 } 1135 1136 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1137 // Currently, there is no facility in the do_full_collection(bool) API to notify 1138 // the caller that the collection did not succeed (e.g., because it was locked 1139 // out by the GC locker). So, right now, we'll ignore the return value. 1140 bool dummy = do_full_collection(true, /* explicit_gc */ 1141 clear_all_soft_refs); 1142 } 1143 1144 void G1CollectedHeap::resize_heap_if_necessary() { 1145 assert_at_safepoint_on_vm_thread(); 1146 1147 bool should_expand; 1148 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand); 1149 1150 if (resize_amount == 0) { 1151 return; 1152 } else if (should_expand) { 1153 expand(resize_amount, _workers); 1154 } else { 1155 shrink(resize_amount); 1156 } 1157 } 1158 1159 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1160 bool do_gc, 1161 bool clear_all_soft_refs, 1162 bool expect_null_mutator_alloc_region, 1163 bool* gc_succeeded) { 1164 *gc_succeeded = true; 1165 // Let's attempt the allocation first. 1166 HeapWord* result = 1167 attempt_allocation_at_safepoint(word_size, 1168 expect_null_mutator_alloc_region); 1169 if (result != NULL) { 1170 return result; 1171 } 1172 1173 // In a G1 heap, we're supposed to keep allocation from failing by 1174 // incremental pauses. Therefore, at least for now, we'll favor 1175 // expansion over collection. (This might change in the future if we can 1176 // do something smarter than full collection to satisfy a failed alloc.) 1177 result = expand_and_allocate(word_size); 1178 if (result != NULL) { 1179 return result; 1180 } 1181 1182 if (do_gc) { 1183 // Expansion didn't work, we'll try to do a Full GC. 1184 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1185 clear_all_soft_refs); 1186 } 1187 1188 return NULL; 1189 } 1190 1191 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1192 bool* succeeded) { 1193 assert_at_safepoint_on_vm_thread(); 1194 1195 // Attempts to allocate followed by Full GC. 1196 HeapWord* result = 1197 satisfy_failed_allocation_helper(word_size, 1198 true, /* do_gc */ 1199 false, /* clear_all_soft_refs */ 1200 false, /* expect_null_mutator_alloc_region */ 1201 succeeded); 1202 1203 if (result != NULL || !*succeeded) { 1204 return result; 1205 } 1206 1207 // Attempts to allocate followed by Full GC that will collect all soft references. 1208 result = satisfy_failed_allocation_helper(word_size, 1209 true, /* do_gc */ 1210 true, /* clear_all_soft_refs */ 1211 true, /* expect_null_mutator_alloc_region */ 1212 succeeded); 1213 1214 if (result != NULL || !*succeeded) { 1215 return result; 1216 } 1217 1218 // Attempts to allocate, no GC 1219 result = satisfy_failed_allocation_helper(word_size, 1220 false, /* do_gc */ 1221 false, /* clear_all_soft_refs */ 1222 true, /* expect_null_mutator_alloc_region */ 1223 succeeded); 1224 1225 if (result != NULL) { 1226 return result; 1227 } 1228 1229 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1230 "Flag should have been handled and cleared prior to this point"); 1231 1232 // What else? We might try synchronous finalization later. If the total 1233 // space available is large enough for the allocation, then a more 1234 // complete compaction phase than we've tried so far might be 1235 // appropriate. 1236 return NULL; 1237 } 1238 1239 // Attempting to expand the heap sufficiently 1240 // to support an allocation of the given "word_size". If 1241 // successful, perform the allocation and return the address of the 1242 // allocated block, or else "NULL". 1243 1244 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1245 assert_at_safepoint_on_vm_thread(); 1246 1247 _verifier->verify_region_sets_optional(); 1248 1249 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1250 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1251 word_size * HeapWordSize); 1252 1253 1254 if (expand(expand_bytes, _workers)) { 1255 _hrm->verify_optional(); 1256 _verifier->verify_region_sets_optional(); 1257 return attempt_allocation_at_safepoint(word_size, 1258 false /* expect_null_mutator_alloc_region */); 1259 } 1260 return NULL; 1261 } 1262 1263 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1264 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1265 aligned_expand_bytes = align_up(aligned_expand_bytes, 1266 HeapRegion::GrainBytes); 1267 1268 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1269 expand_bytes, aligned_expand_bytes); 1270 1271 if (is_maximal_no_gc()) { 1272 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1273 return false; 1274 } 1275 1276 double expand_heap_start_time_sec = os::elapsedTime(); 1277 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1278 assert(regions_to_expand > 0, "Must expand by at least one region"); 1279 1280 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1281 if (expand_time_ms != NULL) { 1282 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1283 } 1284 1285 if (expanded_by > 0) { 1286 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1287 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1288 policy()->record_new_heap_size(num_regions()); 1289 } else { 1290 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1291 1292 // The expansion of the virtual storage space was unsuccessful. 1293 // Let's see if it was because we ran out of swap. 1294 if (G1ExitOnExpansionFailure && 1295 _hrm->available() >= regions_to_expand) { 1296 // We had head room... 1297 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1298 } 1299 } 1300 return regions_to_expand > 0; 1301 } 1302 1303 bool G1CollectedHeap::expand_single_region(uint node_index) { 1304 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1305 1306 if (expanded_by == 0) { 1307 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1308 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1309 return false; 1310 } 1311 1312 policy()->record_new_heap_size(num_regions()); 1313 return true; 1314 } 1315 1316 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1317 size_t aligned_shrink_bytes = 1318 ReservedSpace::page_align_size_down(shrink_bytes); 1319 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1320 HeapRegion::GrainBytes); 1321 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1322 1323 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1324 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1325 1326 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", 1327 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1328 if (num_regions_removed > 0) { 1329 policy()->record_new_heap_size(num_regions()); 1330 } else { 1331 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1332 } 1333 } 1334 1335 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1336 _verifier->verify_region_sets_optional(); 1337 1338 // We should only reach here at the end of a Full GC or during Remark which 1339 // means we should not not be holding to any GC alloc regions. The method 1340 // below will make sure of that and do any remaining clean up. 1341 _allocator->abandon_gc_alloc_regions(); 1342 1343 // Instead of tearing down / rebuilding the free lists here, we 1344 // could instead use the remove_all_pending() method on free_list to 1345 // remove only the ones that we need to remove. 1346 tear_down_region_sets(true /* free_list_only */); 1347 shrink_helper(shrink_bytes); 1348 rebuild_region_sets(true /* free_list_only */); 1349 1350 _hrm->verify_optional(); 1351 _verifier->verify_region_sets_optional(); 1352 } 1353 1354 class OldRegionSetChecker : public HeapRegionSetChecker { 1355 public: 1356 void check_mt_safety() { 1357 // Master Old Set MT safety protocol: 1358 // (a) If we're at a safepoint, operations on the master old set 1359 // should be invoked: 1360 // - by the VM thread (which will serialize them), or 1361 // - by the GC workers while holding the FreeList_lock, if we're 1362 // at a safepoint for an evacuation pause (this lock is taken 1363 // anyway when an GC alloc region is retired so that a new one 1364 // is allocated from the free list), or 1365 // - by the GC workers while holding the OldSets_lock, if we're at a 1366 // safepoint for a cleanup pause. 1367 // (b) If we're not at a safepoint, operations on the master old set 1368 // should be invoked while holding the Heap_lock. 1369 1370 if (SafepointSynchronize::is_at_safepoint()) { 1371 guarantee(Thread::current()->is_VM_thread() || 1372 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1373 "master old set MT safety protocol at a safepoint"); 1374 } else { 1375 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1376 } 1377 } 1378 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1379 const char* get_description() { return "Old Regions"; } 1380 }; 1381 1382 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1383 public: 1384 void check_mt_safety() { 1385 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1386 "May only change archive regions during initialization or safepoint."); 1387 } 1388 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1389 const char* get_description() { return "Archive Regions"; } 1390 }; 1391 1392 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1393 public: 1394 void check_mt_safety() { 1395 // Humongous Set MT safety protocol: 1396 // (a) If we're at a safepoint, operations on the master humongous 1397 // set should be invoked by either the VM thread (which will 1398 // serialize them) or by the GC workers while holding the 1399 // OldSets_lock. 1400 // (b) If we're not at a safepoint, operations on the master 1401 // humongous set should be invoked while holding the Heap_lock. 1402 1403 if (SafepointSynchronize::is_at_safepoint()) { 1404 guarantee(Thread::current()->is_VM_thread() || 1405 OldSets_lock->owned_by_self(), 1406 "master humongous set MT safety protocol at a safepoint"); 1407 } else { 1408 guarantee(Heap_lock->owned_by_self(), 1409 "master humongous set MT safety protocol outside a safepoint"); 1410 } 1411 } 1412 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1413 const char* get_description() { return "Humongous Regions"; } 1414 }; 1415 1416 G1CollectedHeap::G1CollectedHeap() : 1417 CollectedHeap(), 1418 _young_gen_sampling_thread(NULL), 1419 _workers(NULL), 1420 _card_table(NULL), 1421 _collection_pause_end(Ticks::now()), 1422 _soft_ref_policy(), 1423 _old_set("Old Region Set", new OldRegionSetChecker()), 1424 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1425 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1426 _bot(NULL), 1427 _listener(), 1428 _numa(G1NUMA::create()), 1429 _hrm(NULL), 1430 _allocator(NULL), 1431 _verifier(NULL), 1432 _summary_bytes_used(0), 1433 _bytes_used_during_gc(0), 1434 _archive_allocator(NULL), 1435 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1436 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1437 _expand_heap_after_alloc_failure(true), 1438 _g1mm(NULL), 1439 _humongous_reclaim_candidates(), 1440 _has_humongous_reclaim_candidates(false), 1441 _hr_printer(), 1442 _collector_state(), 1443 _old_marking_cycles_started(0), 1444 _old_marking_cycles_completed(0), 1445 _eden(), 1446 _survivor(), 1447 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1448 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1449 _policy(G1Policy::create_policy(_gc_timer_stw)), 1450 _heap_sizing_policy(NULL), 1451 _collection_set(this, _policy), 1452 _hot_card_cache(NULL), 1453 _rem_set(NULL), 1454 _cm(NULL), 1455 _cm_thread(NULL), 1456 _cr(NULL), 1457 _task_queues(NULL), 1458 _evacuation_failed(false), 1459 _evacuation_failed_info_array(NULL), 1460 _preserved_marks_set(true /* in_c_heap */), 1461 #ifndef PRODUCT 1462 _evacuation_failure_alot_for_current_gc(false), 1463 _evacuation_failure_alot_gc_number(0), 1464 _evacuation_failure_alot_count(0), 1465 #endif 1466 _ref_processor_stw(NULL), 1467 _is_alive_closure_stw(this), 1468 _is_subject_to_discovery_stw(this), 1469 _ref_processor_cm(NULL), 1470 _is_alive_closure_cm(this), 1471 _is_subject_to_discovery_cm(this), 1472 _region_attr() { 1473 1474 _verifier = new G1HeapVerifier(this); 1475 1476 _allocator = new G1Allocator(this); 1477 1478 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1479 1480 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1481 1482 // Override the default _filler_array_max_size so that no humongous filler 1483 // objects are created. 1484 _filler_array_max_size = _humongous_object_threshold_in_words; 1485 1486 uint n_queues = ParallelGCThreads; 1487 _task_queues = new G1ScannerTasksQueueSet(n_queues); 1488 1489 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1490 1491 for (uint i = 0; i < n_queues; i++) { 1492 G1ScannerTasksQueue* q = new G1ScannerTasksQueue(); 1493 q->initialize(); 1494 _task_queues->register_queue(i, q); 1495 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1496 } 1497 1498 // Initialize the G1EvacuationFailureALot counters and flags. 1499 NOT_PRODUCT(reset_evacuation_should_fail();) 1500 _gc_tracer_stw->initialize(); 1501 1502 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1503 } 1504 1505 static size_t actual_reserved_page_size(ReservedSpace rs) { 1506 size_t page_size = os::vm_page_size(); 1507 if (UseLargePages) { 1508 // There are two ways to manage large page memory. 1509 // 1. OS supports committing large page memory. 1510 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1511 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1512 // we reserved memory without large page. 1513 if (os::can_commit_large_page_memory() || rs.special()) { 1514 // An alignment at ReservedSpace comes from preferred page size or 1515 // heap alignment, and if the alignment came from heap alignment, it could be 1516 // larger than large pages size. So need to cap with the large page size. 1517 page_size = MIN2(rs.alignment(), os::large_page_size()); 1518 } 1519 } 1520 1521 return page_size; 1522 } 1523 1524 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1525 size_t size, 1526 size_t translation_factor) { 1527 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1528 // Allocate a new reserved space, preferring to use large pages. 1529 ReservedSpace rs(size, preferred_page_size); 1530 size_t page_size = actual_reserved_page_size(rs); 1531 G1RegionToSpaceMapper* result = 1532 G1RegionToSpaceMapper::create_mapper(rs, 1533 size, 1534 page_size, 1535 HeapRegion::GrainBytes, 1536 translation_factor, 1537 mtGC); 1538 1539 os::trace_page_sizes_for_requested_size(description, 1540 size, 1541 preferred_page_size, 1542 page_size, 1543 rs.base(), 1544 rs.size()); 1545 1546 return result; 1547 } 1548 1549 jint G1CollectedHeap::initialize_concurrent_refinement() { 1550 jint ecode = JNI_OK; 1551 _cr = G1ConcurrentRefine::create(&ecode); 1552 return ecode; 1553 } 1554 1555 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1556 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1557 if (_young_gen_sampling_thread->osthread() == NULL) { 1558 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1559 return JNI_ENOMEM; 1560 } 1561 return JNI_OK; 1562 } 1563 1564 jint G1CollectedHeap::initialize() { 1565 1566 // Necessary to satisfy locking discipline assertions. 1567 1568 MutexLocker x(Heap_lock); 1569 1570 // While there are no constraints in the GC code that HeapWordSize 1571 // be any particular value, there are multiple other areas in the 1572 // system which believe this to be true (e.g. oop->object_size in some 1573 // cases incorrectly returns the size in wordSize units rather than 1574 // HeapWordSize). 1575 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1576 1577 size_t init_byte_size = InitialHeapSize; 1578 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1579 1580 // Ensure that the sizes are properly aligned. 1581 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1582 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1583 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1584 1585 // Reserve the maximum. 1586 1587 // When compressed oops are enabled, the preferred heap base 1588 // is calculated by subtracting the requested size from the 1589 // 32Gb boundary and using the result as the base address for 1590 // heap reservation. If the requested size is not aligned to 1591 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1592 // into the ReservedHeapSpace constructor) then the actual 1593 // base of the reserved heap may end up differing from the 1594 // address that was requested (i.e. the preferred heap base). 1595 // If this happens then we could end up using a non-optimal 1596 // compressed oops mode. 1597 1598 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1599 HeapAlignment); 1600 1601 initialize_reserved_region(heap_rs); 1602 1603 // Create the barrier set for the entire reserved region. 1604 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1605 ct->initialize(); 1606 G1BarrierSet* bs = new G1BarrierSet(ct); 1607 bs->initialize(); 1608 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1609 BarrierSet::set_barrier_set(bs); 1610 _card_table = ct; 1611 1612 { 1613 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1614 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1615 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1616 } 1617 1618 // Create the hot card cache. 1619 _hot_card_cache = new G1HotCardCache(this); 1620 1621 // Carve out the G1 part of the heap. 1622 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1623 size_t page_size = actual_reserved_page_size(heap_rs); 1624 G1RegionToSpaceMapper* heap_storage = 1625 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1626 g1_rs.size(), 1627 page_size, 1628 HeapRegion::GrainBytes, 1629 1, 1630 mtJavaHeap); 1631 if(heap_storage == NULL) { 1632 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1633 return JNI_ERR; 1634 } 1635 1636 os::trace_page_sizes("Heap", 1637 MinHeapSize, 1638 reserved_byte_size, 1639 page_size, 1640 heap_rs.base(), 1641 heap_rs.size()); 1642 heap_storage->set_mapping_changed_listener(&_listener); 1643 1644 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1645 G1RegionToSpaceMapper* bot_storage = 1646 create_aux_memory_mapper("Block Offset Table", 1647 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1648 G1BlockOffsetTable::heap_map_factor()); 1649 1650 G1RegionToSpaceMapper* cardtable_storage = 1651 create_aux_memory_mapper("Card Table", 1652 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1653 G1CardTable::heap_map_factor()); 1654 1655 G1RegionToSpaceMapper* card_counts_storage = 1656 create_aux_memory_mapper("Card Counts Table", 1657 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1658 G1CardCounts::heap_map_factor()); 1659 1660 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1661 G1RegionToSpaceMapper* prev_bitmap_storage = 1662 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1663 G1RegionToSpaceMapper* next_bitmap_storage = 1664 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1665 1666 _hrm = HeapRegionManager::create_manager(this); 1667 1668 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1669 _card_table->initialize(cardtable_storage); 1670 1671 // Do later initialization work for concurrent refinement. 1672 _hot_card_cache->initialize(card_counts_storage); 1673 1674 // 6843694 - ensure that the maximum region index can fit 1675 // in the remembered set structures. 1676 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1677 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1678 1679 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1680 // start within the first card. 1681 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1682 // Also create a G1 rem set. 1683 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1684 _rem_set->initialize(max_regions()); 1685 1686 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1687 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1688 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1689 "too many cards per region"); 1690 1691 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1692 1693 _bot = new G1BlockOffsetTable(reserved(), bot_storage); 1694 1695 { 1696 size_t granularity = HeapRegion::GrainBytes; 1697 1698 _region_attr.initialize(reserved(), granularity); 1699 _humongous_reclaim_candidates.initialize(reserved(), granularity); 1700 } 1701 1702 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1703 true /* are_GC_task_threads */, 1704 false /* are_ConcurrentGC_threads */); 1705 if (_workers == NULL) { 1706 return JNI_ENOMEM; 1707 } 1708 _workers->initialize_workers(); 1709 1710 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1711 1712 // Create the G1ConcurrentMark data structure and thread. 1713 // (Must do this late, so that "max_regions" is defined.) 1714 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1715 _cm_thread = _cm->cm_thread(); 1716 1717 // Now expand into the initial heap size. 1718 if (!expand(init_byte_size, _workers)) { 1719 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1720 return JNI_ENOMEM; 1721 } 1722 1723 // Perform any initialization actions delegated to the policy. 1724 policy()->init(this, &_collection_set); 1725 1726 jint ecode = initialize_concurrent_refinement(); 1727 if (ecode != JNI_OK) { 1728 return ecode; 1729 } 1730 1731 ecode = initialize_young_gen_sampling_thread(); 1732 if (ecode != JNI_OK) { 1733 return ecode; 1734 } 1735 1736 { 1737 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1738 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1739 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1740 } 1741 1742 // Here we allocate the dummy HeapRegion that is required by the 1743 // G1AllocRegion class. 1744 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1745 1746 // We'll re-use the same region whether the alloc region will 1747 // require BOT updates or not and, if it doesn't, then a non-young 1748 // region will complain that it cannot support allocations without 1749 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1750 dummy_region->set_eden(); 1751 // Make sure it's full. 1752 dummy_region->set_top(dummy_region->end()); 1753 G1AllocRegion::setup(this, dummy_region); 1754 1755 _allocator->init_mutator_alloc_regions(); 1756 1757 // Do create of the monitoring and management support so that 1758 // values in the heap have been properly initialized. 1759 _g1mm = new G1MonitoringSupport(this); 1760 1761 G1StringDedup::initialize(); 1762 1763 _preserved_marks_set.init(ParallelGCThreads); 1764 1765 _collection_set.initialize(max_regions()); 1766 1767 G1InitLogger::print(); 1768 1769 return JNI_OK; 1770 } 1771 1772 void G1CollectedHeap::stop() { 1773 // Stop all concurrent threads. We do this to make sure these threads 1774 // do not continue to execute and access resources (e.g. logging) 1775 // that are destroyed during shutdown. 1776 _cr->stop(); 1777 _young_gen_sampling_thread->stop(); 1778 _cm_thread->stop(); 1779 if (G1StringDedup::is_enabled()) { 1780 G1StringDedup::stop(); 1781 } 1782 } 1783 1784 void G1CollectedHeap::safepoint_synchronize_begin() { 1785 SuspendibleThreadSet::synchronize(); 1786 } 1787 1788 void G1CollectedHeap::safepoint_synchronize_end() { 1789 SuspendibleThreadSet::desynchronize(); 1790 } 1791 1792 void G1CollectedHeap::post_initialize() { 1793 CollectedHeap::post_initialize(); 1794 ref_processing_init(); 1795 } 1796 1797 void G1CollectedHeap::ref_processing_init() { 1798 // Reference processing in G1 currently works as follows: 1799 // 1800 // * There are two reference processor instances. One is 1801 // used to record and process discovered references 1802 // during concurrent marking; the other is used to 1803 // record and process references during STW pauses 1804 // (both full and incremental). 1805 // * Both ref processors need to 'span' the entire heap as 1806 // the regions in the collection set may be dotted around. 1807 // 1808 // * For the concurrent marking ref processor: 1809 // * Reference discovery is enabled at concurrent start. 1810 // * Reference discovery is disabled and the discovered 1811 // references processed etc during remarking. 1812 // * Reference discovery is MT (see below). 1813 // * Reference discovery requires a barrier (see below). 1814 // * Reference processing may or may not be MT 1815 // (depending on the value of ParallelRefProcEnabled 1816 // and ParallelGCThreads). 1817 // * A full GC disables reference discovery by the CM 1818 // ref processor and abandons any entries on it's 1819 // discovered lists. 1820 // 1821 // * For the STW processor: 1822 // * Non MT discovery is enabled at the start of a full GC. 1823 // * Processing and enqueueing during a full GC is non-MT. 1824 // * During a full GC, references are processed after marking. 1825 // 1826 // * Discovery (may or may not be MT) is enabled at the start 1827 // of an incremental evacuation pause. 1828 // * References are processed near the end of a STW evacuation pause. 1829 // * For both types of GC: 1830 // * Discovery is atomic - i.e. not concurrent. 1831 // * Reference discovery will not need a barrier. 1832 1833 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1834 1835 // Concurrent Mark ref processor 1836 _ref_processor_cm = 1837 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1838 mt_processing, // mt processing 1839 ParallelGCThreads, // degree of mt processing 1840 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1841 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1842 false, // Reference discovery is not atomic 1843 &_is_alive_closure_cm, // is alive closure 1844 true); // allow changes to number of processing threads 1845 1846 // STW ref processor 1847 _ref_processor_stw = 1848 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1849 mt_processing, // mt processing 1850 ParallelGCThreads, // degree of mt processing 1851 (ParallelGCThreads > 1), // mt discovery 1852 ParallelGCThreads, // degree of mt discovery 1853 true, // Reference discovery is atomic 1854 &_is_alive_closure_stw, // is alive closure 1855 true); // allow changes to number of processing threads 1856 } 1857 1858 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1859 return &_soft_ref_policy; 1860 } 1861 1862 size_t G1CollectedHeap::capacity() const { 1863 return _hrm->length() * HeapRegion::GrainBytes; 1864 } 1865 1866 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1867 return _hrm->total_free_bytes(); 1868 } 1869 1870 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1871 _hot_card_cache->drain(cl, worker_id); 1872 } 1873 1874 // Computes the sum of the storage used by the various regions. 1875 size_t G1CollectedHeap::used() const { 1876 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1877 if (_archive_allocator != NULL) { 1878 result += _archive_allocator->used(); 1879 } 1880 return result; 1881 } 1882 1883 size_t G1CollectedHeap::used_unlocked() const { 1884 return _summary_bytes_used; 1885 } 1886 1887 class SumUsedClosure: public HeapRegionClosure { 1888 size_t _used; 1889 public: 1890 SumUsedClosure() : _used(0) {} 1891 bool do_heap_region(HeapRegion* r) { 1892 _used += r->used(); 1893 return false; 1894 } 1895 size_t result() { return _used; } 1896 }; 1897 1898 size_t G1CollectedHeap::recalculate_used() const { 1899 SumUsedClosure blk; 1900 heap_region_iterate(&blk); 1901 return blk.result(); 1902 } 1903 1904 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1905 switch (cause) { 1906 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1907 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1908 case GCCause::_wb_conc_mark: return true; 1909 default : return false; 1910 } 1911 } 1912 1913 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1914 switch (cause) { 1915 case GCCause::_g1_humongous_allocation: return true; 1916 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1917 case GCCause::_wb_breakpoint: return true; 1918 default: return is_user_requested_concurrent_full_gc(cause); 1919 } 1920 } 1921 1922 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 1923 if (policy()->force_upgrade_to_full()) { 1924 return true; 1925 } else if (should_do_concurrent_full_gc(_gc_cause)) { 1926 return false; 1927 } else if (has_regions_left_for_allocation()) { 1928 return false; 1929 } else { 1930 return true; 1931 } 1932 } 1933 1934 #ifndef PRODUCT 1935 void G1CollectedHeap::allocate_dummy_regions() { 1936 // Let's fill up most of the region 1937 size_t word_size = HeapRegion::GrainWords - 1024; 1938 // And as a result the region we'll allocate will be humongous. 1939 guarantee(is_humongous(word_size), "sanity"); 1940 1941 // _filler_array_max_size is set to humongous object threshold 1942 // but temporarily change it to use CollectedHeap::fill_with_object(). 1943 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size); 1944 1945 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1946 // Let's use the existing mechanism for the allocation 1947 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 1948 if (dummy_obj != NULL) { 1949 MemRegion mr(dummy_obj, word_size); 1950 CollectedHeap::fill_with_object(mr); 1951 } else { 1952 // If we can't allocate once, we probably cannot allocate 1953 // again. Let's get out of the loop. 1954 break; 1955 } 1956 } 1957 } 1958 #endif // !PRODUCT 1959 1960 void G1CollectedHeap::increment_old_marking_cycles_started() { 1961 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 1962 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 1963 "Wrong marking cycle count (started: %d, completed: %d)", 1964 _old_marking_cycles_started, _old_marking_cycles_completed); 1965 1966 _old_marking_cycles_started++; 1967 } 1968 1969 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent, 1970 bool whole_heap_examined) { 1971 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 1972 1973 // We assume that if concurrent == true, then the caller is a 1974 // concurrent thread that was joined the Suspendible Thread 1975 // Set. If there's ever a cheap way to check this, we should add an 1976 // assert here. 1977 1978 // Given that this method is called at the end of a Full GC or of a 1979 // concurrent cycle, and those can be nested (i.e., a Full GC can 1980 // interrupt a concurrent cycle), the number of full collections 1981 // completed should be either one (in the case where there was no 1982 // nesting) or two (when a Full GC interrupted a concurrent cycle) 1983 // behind the number of full collections started. 1984 1985 // This is the case for the inner caller, i.e. a Full GC. 1986 assert(concurrent || 1987 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 1988 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 1989 "for inner caller (Full GC): _old_marking_cycles_started = %u " 1990 "is inconsistent with _old_marking_cycles_completed = %u", 1991 _old_marking_cycles_started, _old_marking_cycles_completed); 1992 1993 // This is the case for the outer caller, i.e. the concurrent cycle. 1994 assert(!concurrent || 1995 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 1996 "for outer caller (concurrent cycle): " 1997 "_old_marking_cycles_started = %u " 1998 "is inconsistent with _old_marking_cycles_completed = %u", 1999 _old_marking_cycles_started, _old_marking_cycles_completed); 2000 2001 _old_marking_cycles_completed += 1; 2002 if (whole_heap_examined) { 2003 // Signal that we have completed a visit to all live objects. 2004 record_whole_heap_examined_timestamp(); 2005 } 2006 2007 // We need to clear the "in_progress" flag in the CM thread before 2008 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2009 // is set) so that if a waiter requests another System.gc() it doesn't 2010 // incorrectly see that a marking cycle is still in progress. 2011 if (concurrent) { 2012 _cm_thread->set_idle(); 2013 } 2014 2015 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 2016 // for a full GC to finish that their wait is over. 2017 ml.notify_all(); 2018 } 2019 2020 void G1CollectedHeap::collect(GCCause::Cause cause) { 2021 try_collect(cause); 2022 } 2023 2024 // Return true if (x < y) with allowance for wraparound. 2025 static bool gc_counter_less_than(uint x, uint y) { 2026 return (x - y) > (UINT_MAX/2); 2027 } 2028 2029 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 2030 // Macro so msg printing is format-checked. 2031 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 2032 do { \ 2033 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 2034 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 2035 ResourceMark rm; /* For thread name. */ \ 2036 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 2037 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 2038 Thread::current()->name(), \ 2039 GCCause::to_string(cause)); \ 2040 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 2041 } \ 2042 } while (0) 2043 2044 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 2045 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 2046 2047 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 2048 uint gc_counter, 2049 uint old_marking_started_before) { 2050 assert_heap_not_locked(); 2051 assert(should_do_concurrent_full_gc(cause), 2052 "Non-concurrent cause %s", GCCause::to_string(cause)); 2053 2054 for (uint i = 1; true; ++i) { 2055 // Try to schedule concurrent start evacuation pause that will 2056 // start a concurrent cycle. 2057 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 2058 VM_G1TryInitiateConcMark op(gc_counter, 2059 cause, 2060 policy()->max_pause_time_ms()); 2061 VMThread::execute(&op); 2062 2063 // Request is trivially finished. 2064 if (cause == GCCause::_g1_periodic_collection) { 2065 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 2066 return op.gc_succeeded(); 2067 } 2068 2069 // If VMOp skipped initiating concurrent marking cycle because 2070 // we're terminating, then we're done. 2071 if (op.terminating()) { 2072 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 2073 return false; 2074 } 2075 2076 // Lock to get consistent set of values. 2077 uint old_marking_started_after; 2078 uint old_marking_completed_after; 2079 { 2080 MutexLocker ml(Heap_lock); 2081 // Update gc_counter for retrying VMOp if needed. Captured here to be 2082 // consistent with the values we use below for termination tests. If 2083 // a retry is needed after a possible wait, and another collection 2084 // occurs in the meantime, it will cause our retry to be skipped and 2085 // we'll recheck for termination with updated conditions from that 2086 // more recent collection. That's what we want, rather than having 2087 // our retry possibly perform an unnecessary collection. 2088 gc_counter = total_collections(); 2089 old_marking_started_after = _old_marking_cycles_started; 2090 old_marking_completed_after = _old_marking_cycles_completed; 2091 } 2092 2093 if (cause == GCCause::_wb_breakpoint) { 2094 if (op.gc_succeeded()) { 2095 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2096 return true; 2097 } 2098 // When _wb_breakpoint there can't be another cycle or deferred. 2099 assert(!op.cycle_already_in_progress(), "invariant"); 2100 assert(!op.whitebox_attached(), "invariant"); 2101 // Concurrent cycle attempt might have been cancelled by some other 2102 // collection, so retry. Unlike other cases below, we want to retry 2103 // even if cancelled by a STW full collection, because we really want 2104 // to start a concurrent cycle. 2105 if (old_marking_started_before != old_marking_started_after) { 2106 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 2107 old_marking_started_before = old_marking_started_after; 2108 } 2109 } else if (!GCCause::is_user_requested_gc(cause)) { 2110 // For an "automatic" (not user-requested) collection, we just need to 2111 // ensure that progress is made. 2112 // 2113 // Request is finished if any of 2114 // (1) the VMOp successfully performed a GC, 2115 // (2) a concurrent cycle was already in progress, 2116 // (3) whitebox is controlling concurrent cycles, 2117 // (4) a new cycle was started (by this thread or some other), or 2118 // (5) a Full GC was performed. 2119 // Cases (4) and (5) are detected together by a change to 2120 // _old_marking_cycles_started. 2121 // 2122 // Note that (1) does not imply (4). If we're still in the mixed 2123 // phase of an earlier concurrent collection, the request to make the 2124 // collection a concurrent start won't be honored. If we don't check for 2125 // both conditions we'll spin doing back-to-back collections. 2126 if (op.gc_succeeded() || 2127 op.cycle_already_in_progress() || 2128 op.whitebox_attached() || 2129 (old_marking_started_before != old_marking_started_after)) { 2130 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2131 return true; 2132 } 2133 } else { // User-requested GC. 2134 // For a user-requested collection, we want to ensure that a complete 2135 // full collection has been performed before returning, but without 2136 // waiting for more than needed. 2137 2138 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 2139 // new cycle was started. That's good, because it's not clear what we 2140 // should do otherwise. Trying again just does back to back GCs. 2141 // Can't wait for someone else to start a cycle. And returning fails 2142 // to meet the goal of ensuring a full collection was performed. 2143 assert(!op.gc_succeeded() || 2144 (old_marking_started_before != old_marking_started_after), 2145 "invariant: succeeded %s, started before %u, started after %u", 2146 BOOL_TO_STR(op.gc_succeeded()), 2147 old_marking_started_before, old_marking_started_after); 2148 2149 // Request is finished if a full collection (concurrent or stw) 2150 // was started after this request and has completed, e.g. 2151 // started_before < completed_after. 2152 if (gc_counter_less_than(old_marking_started_before, 2153 old_marking_completed_after)) { 2154 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2155 return true; 2156 } 2157 2158 if (old_marking_started_after != old_marking_completed_after) { 2159 // If there is an in-progress cycle (possibly started by us), then 2160 // wait for that cycle to complete, e.g. 2161 // while completed_now < started_after. 2162 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2163 MonitorLocker ml(G1OldGCCount_lock); 2164 while (gc_counter_less_than(_old_marking_cycles_completed, 2165 old_marking_started_after)) { 2166 ml.wait(); 2167 } 2168 // Request is finished if the collection we just waited for was 2169 // started after this request. 2170 if (old_marking_started_before != old_marking_started_after) { 2171 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2172 return true; 2173 } 2174 } 2175 2176 // If VMOp was successful then it started a new cycle that the above 2177 // wait &etc should have recognized as finishing this request. This 2178 // differs from a non-user-request, where gc_succeeded does not imply 2179 // a new cycle was started. 2180 assert(!op.gc_succeeded(), "invariant"); 2181 2182 if (op.cycle_already_in_progress()) { 2183 // If VMOp failed because a cycle was already in progress, it 2184 // is now complete. But it didn't finish this user-requested 2185 // GC, so try again. 2186 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2187 continue; 2188 } else if (op.whitebox_attached()) { 2189 // If WhiteBox wants control, wait for notification of a state 2190 // change in the controller, then try again. Don't wait for 2191 // release of control, since collections may complete while in 2192 // control. Note: This won't recognize a STW full collection 2193 // while waiting; we can't wait on multiple monitors. 2194 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 2195 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 2196 if (ConcurrentGCBreakpoints::is_controlled()) { 2197 ml.wait(); 2198 } 2199 continue; 2200 } 2201 } 2202 2203 // Collection failed and should be retried. 2204 assert(op.transient_failure(), "invariant"); 2205 2206 if (GCLocker::is_active_and_needs_gc()) { 2207 // If GCLocker is active, wait until clear before retrying. 2208 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2209 GCLocker::stall_until_clear(); 2210 } 2211 2212 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2213 } 2214 } 2215 2216 bool G1CollectedHeap::try_collect(GCCause::Cause cause) { 2217 assert_heap_not_locked(); 2218 2219 // Lock to get consistent set of values. 2220 uint gc_count_before; 2221 uint full_gc_count_before; 2222 uint old_marking_started_before; 2223 { 2224 MutexLocker ml(Heap_lock); 2225 gc_count_before = total_collections(); 2226 full_gc_count_before = total_full_collections(); 2227 old_marking_started_before = _old_marking_cycles_started; 2228 } 2229 2230 if (should_do_concurrent_full_gc(cause)) { 2231 return try_collect_concurrently(cause, 2232 gc_count_before, 2233 old_marking_started_before); 2234 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2235 // Indicate failure to be consistent with VMOp failure due to 2236 // another collection slipping in after our gc_count but before 2237 // our request is processed. 2238 return false; 2239 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2240 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2241 2242 // Schedule a standard evacuation pause. We're setting word_size 2243 // to 0 which means that we are not requesting a post-GC allocation. 2244 VM_G1CollectForAllocation op(0, /* word_size */ 2245 gc_count_before, 2246 cause, 2247 policy()->max_pause_time_ms()); 2248 VMThread::execute(&op); 2249 return op.gc_succeeded(); 2250 } else { 2251 // Schedule a Full GC. 2252 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2253 VMThread::execute(&op); 2254 return op.gc_succeeded(); 2255 } 2256 } 2257 2258 bool G1CollectedHeap::is_in(const void* p) const { 2259 if (_hrm->reserved().contains(p)) { 2260 // Given that we know that p is in the reserved space, 2261 // heap_region_containing() should successfully 2262 // return the containing region. 2263 HeapRegion* hr = heap_region_containing(p); 2264 return hr->is_in(p); 2265 } else { 2266 return false; 2267 } 2268 } 2269 2270 #ifdef ASSERT 2271 bool G1CollectedHeap::is_in_exact(const void* p) const { 2272 bool contains = reserved().contains(p); 2273 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2274 if (contains && available) { 2275 return true; 2276 } else { 2277 return false; 2278 } 2279 } 2280 #endif 2281 2282 // Iteration functions. 2283 2284 // Iterates an ObjectClosure over all objects within a HeapRegion. 2285 2286 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2287 ObjectClosure* _cl; 2288 public: 2289 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2290 bool do_heap_region(HeapRegion* r) { 2291 if (!r->is_continues_humongous()) { 2292 r->object_iterate(_cl); 2293 } 2294 return false; 2295 } 2296 }; 2297 2298 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2299 IterateObjectClosureRegionClosure blk(cl); 2300 heap_region_iterate(&blk); 2301 } 2302 2303 class G1ParallelObjectIterator : public ParallelObjectIterator { 2304 private: 2305 G1CollectedHeap* _heap; 2306 HeapRegionClaimer _claimer; 2307 2308 public: 2309 G1ParallelObjectIterator(uint thread_num) : 2310 _heap(G1CollectedHeap::heap()), 2311 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {} 2312 2313 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 2314 _heap->object_iterate_parallel(cl, worker_id, &_claimer); 2315 } 2316 }; 2317 2318 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) { 2319 return new G1ParallelObjectIterator(thread_num); 2320 } 2321 2322 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) { 2323 IterateObjectClosureRegionClosure blk(cl); 2324 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id); 2325 } 2326 2327 void G1CollectedHeap::keep_alive(oop obj) { 2328 G1BarrierSet::enqueue(obj); 2329 } 2330 2331 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2332 _hrm->iterate(cl); 2333 } 2334 2335 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2336 HeapRegionClaimer *hrclaimer, 2337 uint worker_id) const { 2338 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2339 } 2340 2341 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2342 HeapRegionClaimer *hrclaimer) const { 2343 _hrm->par_iterate(cl, hrclaimer, 0); 2344 } 2345 2346 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2347 _collection_set.iterate(cl); 2348 } 2349 2350 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2351 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers()); 2352 } 2353 2354 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2355 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2356 } 2357 2358 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2359 HeapRegion* hr = heap_region_containing(addr); 2360 return hr->block_start(addr); 2361 } 2362 2363 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2364 HeapRegion* hr = heap_region_containing(addr); 2365 return hr->block_is_obj(addr); 2366 } 2367 2368 bool G1CollectedHeap::supports_tlab_allocation() const { 2369 return true; 2370 } 2371 2372 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2373 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2374 } 2375 2376 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2377 return _eden.length() * HeapRegion::GrainBytes; 2378 } 2379 2380 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2381 // must be equal to the humongous object limit. 2382 size_t G1CollectedHeap::max_tlab_size() const { 2383 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2384 } 2385 2386 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2387 return _allocator->unsafe_max_tlab_alloc(); 2388 } 2389 2390 size_t G1CollectedHeap::max_capacity() const { 2391 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2392 } 2393 2394 void G1CollectedHeap::deduplicate_string(oop str) { 2395 assert(java_lang_String::is_instance(str), "invariant"); 2396 2397 if (G1StringDedup::is_enabled()) { 2398 G1StringDedup::deduplicate(str); 2399 } 2400 } 2401 2402 void G1CollectedHeap::prepare_for_verify() { 2403 _verifier->prepare_for_verify(); 2404 } 2405 2406 void G1CollectedHeap::verify(VerifyOption vo) { 2407 _verifier->verify(vo); 2408 } 2409 2410 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2411 return true; 2412 } 2413 2414 bool G1CollectedHeap::is_heterogeneous_heap() const { 2415 return G1Arguments::is_heterogeneous_heap(); 2416 } 2417 2418 class PrintRegionClosure: public HeapRegionClosure { 2419 outputStream* _st; 2420 public: 2421 PrintRegionClosure(outputStream* st) : _st(st) {} 2422 bool do_heap_region(HeapRegion* r) { 2423 r->print_on(_st); 2424 return false; 2425 } 2426 }; 2427 2428 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2429 const HeapRegion* hr, 2430 const VerifyOption vo) const { 2431 switch (vo) { 2432 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2433 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2434 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2435 default: ShouldNotReachHere(); 2436 } 2437 return false; // keep some compilers happy 2438 } 2439 2440 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2441 const VerifyOption vo) const { 2442 switch (vo) { 2443 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2444 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2445 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2446 default: ShouldNotReachHere(); 2447 } 2448 return false; // keep some compilers happy 2449 } 2450 2451 void G1CollectedHeap::print_heap_regions() const { 2452 LogTarget(Trace, gc, heap, region) lt; 2453 if (lt.is_enabled()) { 2454 LogStream ls(lt); 2455 print_regions_on(&ls); 2456 } 2457 } 2458 2459 void G1CollectedHeap::print_on(outputStream* st) const { 2460 st->print(" %-20s", "garbage-first heap"); 2461 if (_hrm != NULL) { 2462 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2463 capacity()/K, used_unlocked()/K); 2464 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2465 p2i(_hrm->reserved().start()), 2466 p2i(_hrm->reserved().end())); 2467 } 2468 st->cr(); 2469 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2470 uint young_regions = young_regions_count(); 2471 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2472 (size_t) young_regions * HeapRegion::GrainBytes / K); 2473 uint survivor_regions = survivor_regions_count(); 2474 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2475 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2476 st->cr(); 2477 if (_numa->is_enabled()) { 2478 uint num_nodes = _numa->num_active_nodes(); 2479 st->print(" remaining free region(s) on each NUMA node: "); 2480 const int* node_ids = _numa->node_ids(); 2481 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2482 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0); 2483 st->print("%d=%u ", node_ids[node_index], num_free_regions); 2484 } 2485 st->cr(); 2486 } 2487 MetaspaceUtils::print_on(st); 2488 } 2489 2490 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2491 if (_hrm == NULL) { 2492 return; 2493 } 2494 2495 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2496 "HS=humongous(starts), HC=humongous(continues), " 2497 "CS=collection set, F=free, " 2498 "OA=open archive, CA=closed archive, " 2499 "TAMS=top-at-mark-start (previous, next)"); 2500 PrintRegionClosure blk(st); 2501 heap_region_iterate(&blk); 2502 } 2503 2504 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2505 print_on(st); 2506 2507 // Print the per-region information. 2508 if (_hrm != NULL) { 2509 st->cr(); 2510 print_regions_on(st); 2511 } 2512 } 2513 2514 void G1CollectedHeap::print_on_error(outputStream* st) const { 2515 this->CollectedHeap::print_on_error(st); 2516 2517 if (_cm != NULL) { 2518 st->cr(); 2519 _cm->print_on_error(st); 2520 } 2521 } 2522 2523 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2524 workers()->threads_do(tc); 2525 tc->do_thread(_cm_thread); 2526 _cm->threads_do(tc); 2527 _cr->threads_do(tc); 2528 tc->do_thread(_young_gen_sampling_thread); 2529 if (G1StringDedup::is_enabled()) { 2530 G1StringDedup::threads_do(tc); 2531 } 2532 } 2533 2534 void G1CollectedHeap::print_tracing_info() const { 2535 rem_set()->print_summary_info(); 2536 concurrent_mark()->print_summary_info(); 2537 } 2538 2539 #ifndef PRODUCT 2540 // Helpful for debugging RSet issues. 2541 2542 class PrintRSetsClosure : public HeapRegionClosure { 2543 private: 2544 const char* _msg; 2545 size_t _occupied_sum; 2546 2547 public: 2548 bool do_heap_region(HeapRegion* r) { 2549 HeapRegionRemSet* hrrs = r->rem_set(); 2550 size_t occupied = hrrs->occupied(); 2551 _occupied_sum += occupied; 2552 2553 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2554 if (occupied == 0) { 2555 tty->print_cr(" RSet is empty"); 2556 } else { 2557 hrrs->print(); 2558 } 2559 tty->print_cr("----------"); 2560 return false; 2561 } 2562 2563 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2564 tty->cr(); 2565 tty->print_cr("========================================"); 2566 tty->print_cr("%s", msg); 2567 tty->cr(); 2568 } 2569 2570 ~PrintRSetsClosure() { 2571 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2572 tty->print_cr("========================================"); 2573 tty->cr(); 2574 } 2575 }; 2576 2577 void G1CollectedHeap::print_cset_rsets() { 2578 PrintRSetsClosure cl("Printing CSet RSets"); 2579 collection_set_iterate_all(&cl); 2580 } 2581 2582 void G1CollectedHeap::print_all_rsets() { 2583 PrintRSetsClosure cl("Printing All RSets");; 2584 heap_region_iterate(&cl); 2585 } 2586 #endif // PRODUCT 2587 2588 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2589 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2590 } 2591 2592 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2593 2594 size_t eden_used_bytes = _eden.used_bytes(); 2595 size_t survivor_used_bytes = _survivor.used_bytes(); 2596 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2597 2598 size_t eden_capacity_bytes = 2599 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2600 2601 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2602 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2603 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2604 } 2605 2606 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2607 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2608 stats->unused(), stats->used(), stats->region_end_waste(), 2609 stats->regions_filled(), stats->direct_allocated(), 2610 stats->failure_used(), stats->failure_waste()); 2611 } 2612 2613 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2614 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2615 gc_tracer->report_gc_heap_summary(when, heap_summary); 2616 2617 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2618 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2619 } 2620 2621 void G1CollectedHeap::gc_prologue(bool full) { 2622 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2623 2624 // This summary needs to be printed before incrementing total collections. 2625 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2626 2627 // Update common counters. 2628 increment_total_collections(full /* full gc */); 2629 if (full || collector_state()->in_concurrent_start_gc()) { 2630 increment_old_marking_cycles_started(); 2631 } 2632 2633 // Fill TLAB's and such 2634 { 2635 Ticks start = Ticks::now(); 2636 ensure_parsability(true); 2637 Tickspan dt = Ticks::now() - start; 2638 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS); 2639 } 2640 2641 if (!full) { 2642 // Flush dirty card queues to qset, so later phases don't need to account 2643 // for partially filled per-thread queues and such. Not needed for full 2644 // collections, which ignore those logs. 2645 Ticks start = Ticks::now(); 2646 G1BarrierSet::dirty_card_queue_set().concatenate_logs(); 2647 Tickspan dt = Ticks::now() - start; 2648 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS); 2649 } 2650 } 2651 2652 void G1CollectedHeap::gc_epilogue(bool full) { 2653 // Update common counters. 2654 if (full) { 2655 // Update the number of full collections that have been completed. 2656 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */); 2657 } 2658 2659 // We are at the end of the GC. Total collections has already been increased. 2660 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2661 2662 // FIXME: what is this about? 2663 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2664 // is set. 2665 #if COMPILER2_OR_JVMCI 2666 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2667 #endif 2668 2669 double start = os::elapsedTime(); 2670 resize_all_tlabs(); 2671 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2672 2673 MemoryService::track_memory_usage(); 2674 // We have just completed a GC. Update the soft reference 2675 // policy with the new heap occupancy 2676 Universe::update_heap_info_at_gc(); 2677 2678 // Print NUMA statistics. 2679 _numa->print_statistics(); 2680 2681 _collection_pause_end = Ticks::now(); 2682 } 2683 2684 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2685 LogTarget(Trace, gc, heap, verify) lt; 2686 2687 if (lt.is_enabled()) { 2688 LogStream ls(lt); 2689 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2690 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2691 heap_region_iterate(&cl); 2692 } 2693 } 2694 2695 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2696 uint gc_count_before, 2697 bool* succeeded, 2698 GCCause::Cause gc_cause) { 2699 assert_heap_not_locked_and_not_at_safepoint(); 2700 VM_G1CollectForAllocation op(word_size, 2701 gc_count_before, 2702 gc_cause, 2703 policy()->max_pause_time_ms()); 2704 VMThread::execute(&op); 2705 2706 HeapWord* result = op.result(); 2707 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2708 assert(result == NULL || ret_succeeded, 2709 "the result should be NULL if the VM did not succeed"); 2710 *succeeded = ret_succeeded; 2711 2712 assert_heap_not_locked(); 2713 return result; 2714 } 2715 2716 void G1CollectedHeap::do_concurrent_mark() { 2717 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2718 if (!_cm_thread->in_progress()) { 2719 _cm_thread->set_started(); 2720 CGC_lock->notify(); 2721 } 2722 } 2723 2724 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2725 // We don't nominate objects with many remembered set entries, on 2726 // the assumption that such objects are likely still live. 2727 HeapRegionRemSet* rem_set = r->rem_set(); 2728 2729 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2730 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2731 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2732 } 2733 2734 #ifndef PRODUCT 2735 void G1CollectedHeap::verify_region_attr_remset_update() { 2736 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2737 public: 2738 virtual bool do_heap_region(HeapRegion* r) { 2739 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2740 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2741 assert(r->rem_set()->is_tracked() == needs_remset_update, 2742 "Region %u remset tracking status (%s) different to region attribute (%s)", 2743 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2744 return false; 2745 } 2746 } cl; 2747 heap_region_iterate(&cl); 2748 } 2749 #endif 2750 2751 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2752 public: 2753 bool do_heap_region(HeapRegion* hr) { 2754 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2755 hr->verify_rem_set(); 2756 } 2757 return false; 2758 } 2759 }; 2760 2761 uint G1CollectedHeap::num_task_queues() const { 2762 return _task_queues->size(); 2763 } 2764 2765 #if TASKQUEUE_STATS 2766 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2767 st->print_raw_cr("GC Task Stats"); 2768 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2769 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2770 } 2771 2772 void G1CollectedHeap::print_taskqueue_stats() const { 2773 if (!log_is_enabled(Trace, gc, task, stats)) { 2774 return; 2775 } 2776 Log(gc, task, stats) log; 2777 ResourceMark rm; 2778 LogStream ls(log.trace()); 2779 outputStream* st = &ls; 2780 2781 print_taskqueue_stats_hdr(st); 2782 2783 TaskQueueStats totals; 2784 const uint n = num_task_queues(); 2785 for (uint i = 0; i < n; ++i) { 2786 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2787 totals += task_queue(i)->stats; 2788 } 2789 st->print_raw("tot "); totals.print(st); st->cr(); 2790 2791 DEBUG_ONLY(totals.verify()); 2792 } 2793 2794 void G1CollectedHeap::reset_taskqueue_stats() { 2795 const uint n = num_task_queues(); 2796 for (uint i = 0; i < n; ++i) { 2797 task_queue(i)->stats.reset(); 2798 } 2799 } 2800 #endif // TASKQUEUE_STATS 2801 2802 void G1CollectedHeap::wait_for_root_region_scanning() { 2803 double scan_wait_start = os::elapsedTime(); 2804 // We have to wait until the CM threads finish scanning the 2805 // root regions as it's the only way to ensure that all the 2806 // objects on them have been correctly scanned before we start 2807 // moving them during the GC. 2808 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2809 double wait_time_ms = 0.0; 2810 if (waited) { 2811 double scan_wait_end = os::elapsedTime(); 2812 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2813 } 2814 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2815 } 2816 2817 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2818 private: 2819 G1HRPrinter* _hr_printer; 2820 public: 2821 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2822 2823 virtual bool do_heap_region(HeapRegion* r) { 2824 _hr_printer->cset(r); 2825 return false; 2826 } 2827 }; 2828 2829 void G1CollectedHeap::start_new_collection_set() { 2830 double start = os::elapsedTime(); 2831 2832 collection_set()->start_incremental_building(); 2833 2834 clear_region_attr(); 2835 2836 guarantee(_eden.length() == 0, "eden should have been cleared"); 2837 policy()->transfer_survivors_to_cset(survivor()); 2838 2839 // We redo the verification but now wrt to the new CSet which 2840 // has just got initialized after the previous CSet was freed. 2841 _cm->verify_no_collection_set_oops(); 2842 2843 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2844 } 2845 2846 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2847 2848 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2849 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2850 collection_set()->optional_region_length()); 2851 2852 _cm->verify_no_collection_set_oops(); 2853 2854 if (_hr_printer.is_active()) { 2855 G1PrintCollectionSetClosure cl(&_hr_printer); 2856 _collection_set.iterate(&cl); 2857 _collection_set.iterate_optional(&cl); 2858 } 2859 } 2860 2861 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2862 if (collector_state()->in_concurrent_start_gc()) { 2863 return G1HeapVerifier::G1VerifyConcurrentStart; 2864 } else if (collector_state()->in_young_only_phase()) { 2865 return G1HeapVerifier::G1VerifyYoungNormal; 2866 } else { 2867 return G1HeapVerifier::G1VerifyMixed; 2868 } 2869 } 2870 2871 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2872 if (VerifyRememberedSets) { 2873 log_info(gc, verify)("[Verifying RemSets before GC]"); 2874 VerifyRegionRemSetClosure v_cl; 2875 heap_region_iterate(&v_cl); 2876 } 2877 _verifier->verify_before_gc(type); 2878 _verifier->check_bitmaps("GC Start"); 2879 verify_numa_regions("GC Start"); 2880 } 2881 2882 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2883 if (VerifyRememberedSets) { 2884 log_info(gc, verify)("[Verifying RemSets after GC]"); 2885 VerifyRegionRemSetClosure v_cl; 2886 heap_region_iterate(&v_cl); 2887 } 2888 _verifier->verify_after_gc(type); 2889 _verifier->check_bitmaps("GC End"); 2890 verify_numa_regions("GC End"); 2891 } 2892 2893 void G1CollectedHeap::expand_heap_after_young_collection(){ 2894 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount(); 2895 if (expand_bytes > 0) { 2896 // No need for an ergo logging here, 2897 // expansion_amount() does this when it returns a value > 0. 2898 double expand_ms; 2899 if (!expand(expand_bytes, _workers, &expand_ms)) { 2900 // We failed to expand the heap. Cannot do anything about it. 2901 } 2902 phase_times()->record_expand_heap_time(expand_ms); 2903 } 2904 } 2905 2906 const char* G1CollectedHeap::young_gc_name() const { 2907 if (collector_state()->in_concurrent_start_gc()) { 2908 return "Pause Young (Concurrent Start)"; 2909 } else if (collector_state()->in_young_only_phase()) { 2910 if (collector_state()->in_young_gc_before_mixed()) { 2911 return "Pause Young (Prepare Mixed)"; 2912 } else { 2913 return "Pause Young (Normal)"; 2914 } 2915 } else { 2916 return "Pause Young (Mixed)"; 2917 } 2918 } 2919 2920 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2921 assert_at_safepoint_on_vm_thread(); 2922 guarantee(!is_gc_active(), "collection is not reentrant"); 2923 2924 if (GCLocker::check_active_before_gc()) { 2925 return false; 2926 } 2927 2928 do_collection_pause_at_safepoint_helper(target_pause_time_ms); 2929 if (should_upgrade_to_full_gc(gc_cause())) { 2930 log_info(gc, ergo)("Attempting maximally compacting collection"); 2931 bool result = do_full_collection(false /* explicit gc */, 2932 true /* clear_all_soft_refs */); 2933 // do_full_collection only fails if blocked by GC locker, but 2934 // we've already checked for that above. 2935 assert(result, "invariant"); 2936 } 2937 return true; 2938 } 2939 2940 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) { 2941 GCIdMark gc_id_mark; 2942 2943 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2944 ResourceMark rm; 2945 2946 policy()->note_gc_start(); 2947 2948 _gc_timer_stw->register_gc_start(); 2949 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2950 2951 wait_for_root_region_scanning(); 2952 2953 print_heap_before_gc(); 2954 print_heap_regions(); 2955 trace_heap_before_gc(_gc_tracer_stw); 2956 2957 _verifier->verify_region_sets_optional(); 2958 _verifier->verify_dirty_young_regions(); 2959 2960 // We should not be doing concurrent start unless the concurrent mark thread is running 2961 if (!_cm_thread->should_terminate()) { 2962 // This call will decide whether this pause is a concurrent start 2963 // pause. If it is, in_concurrent_start_gc() will return true 2964 // for the duration of this pause. 2965 policy()->decide_on_conc_mark_initiation(); 2966 } 2967 2968 // We do not allow concurrent start to be piggy-backed on a mixed GC. 2969 assert(!collector_state()->in_concurrent_start_gc() || 2970 collector_state()->in_young_only_phase(), "sanity"); 2971 // We also do not allow mixed GCs during marking. 2972 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2973 2974 // Record whether this pause is a concurrent start. When the current 2975 // thread has completed its logging output and it's safe to signal 2976 // the CM thread, the flag's value in the policy has been reset. 2977 bool should_start_conc_mark = collector_state()->in_concurrent_start_gc(); 2978 if (should_start_conc_mark) { 2979 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2980 } 2981 2982 // Inner scope for scope based logging, timers, and stats collection 2983 { 2984 G1EvacuationInfo evacuation_info; 2985 2986 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2987 2988 GCTraceCPUTime tcpu; 2989 2990 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 2991 2992 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2993 workers()->active_workers(), 2994 Threads::number_of_non_daemon_threads()); 2995 active_workers = workers()->update_active_workers(active_workers); 2996 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2997 2998 G1MonitoringScope ms(g1mm(), 2999 false /* full_gc */, 3000 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3001 3002 G1HeapTransition heap_transition(this); 3003 3004 { 3005 IsGCActiveMark x; 3006 3007 gc_prologue(false); 3008 3009 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3010 verify_before_young_collection(verify_type); 3011 3012 { 3013 // The elapsed time induced by the start time below deliberately elides 3014 // the possible verification above. 3015 double sample_start_time_sec = os::elapsedTime(); 3016 3017 // Please see comment in g1CollectedHeap.hpp and 3018 // G1CollectedHeap::ref_processing_init() to see how 3019 // reference processing currently works in G1. 3020 _ref_processor_stw->enable_discovery(); 3021 3022 // We want to temporarily turn off discovery by the 3023 // CM ref processor, if necessary, and turn it back on 3024 // on again later if we do. Using a scoped 3025 // NoRefDiscovery object will do this. 3026 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3027 3028 policy()->record_collection_pause_start(sample_start_time_sec); 3029 3030 // Forget the current allocation region (we might even choose it to be part 3031 // of the collection set!). 3032 _allocator->release_mutator_alloc_regions(); 3033 3034 calculate_collection_set(evacuation_info, target_pause_time_ms); 3035 3036 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3037 G1ParScanThreadStateSet per_thread_states(this, 3038 &rdcqs, 3039 workers()->active_workers(), 3040 collection_set()->young_region_length(), 3041 collection_set()->optional_region_length()); 3042 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3043 3044 // Actually do the work... 3045 evacuate_initial_collection_set(&per_thread_states); 3046 3047 if (_collection_set.optional_region_length() != 0) { 3048 evacuate_optional_collection_set(&per_thread_states); 3049 } 3050 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3051 3052 start_new_collection_set(); 3053 3054 _survivor_evac_stats.adjust_desired_plab_sz(); 3055 _old_evac_stats.adjust_desired_plab_sz(); 3056 3057 if (should_start_conc_mark) { 3058 // We have to do this before we notify the CM threads that 3059 // they can start working to make sure that all the 3060 // appropriate initialization is done on the CM object. 3061 concurrent_mark()->post_concurrent_start(); 3062 // Note that we don't actually trigger the CM thread at 3063 // this point. We do that later when we're sure that 3064 // the current thread has completed its logging output. 3065 } 3066 3067 allocate_dummy_regions(); 3068 3069 _allocator->init_mutator_alloc_regions(); 3070 3071 expand_heap_after_young_collection(); 3072 3073 double sample_end_time_sec = os::elapsedTime(); 3074 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3075 policy()->record_collection_pause_end(pause_time_ms); 3076 } 3077 3078 verify_after_young_collection(verify_type); 3079 3080 gc_epilogue(false); 3081 } 3082 3083 // Print the remainder of the GC log output. 3084 if (evacuation_failed()) { 3085 log_info(gc)("To-space exhausted"); 3086 } 3087 3088 policy()->print_phases(); 3089 heap_transition.print(); 3090 3091 _hrm->verify_optional(); 3092 _verifier->verify_region_sets_optional(); 3093 3094 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3095 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3096 3097 print_heap_after_gc(); 3098 print_heap_regions(); 3099 trace_heap_after_gc(_gc_tracer_stw); 3100 3101 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3102 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3103 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3104 // before any GC notifications are raised. 3105 g1mm()->update_sizes(); 3106 3107 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3108 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3109 _gc_timer_stw->register_gc_end(); 3110 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3111 } 3112 // It should now be safe to tell the concurrent mark thread to start 3113 // without its logging output interfering with the logging output 3114 // that came from the pause. 3115 3116 if (should_start_conc_mark) { 3117 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3118 // thread(s) could be running concurrently with us. Make sure that anything 3119 // after this point does not assume that we are the only GC thread running. 3120 // Note: of course, the actual marking work will not start until the safepoint 3121 // itself is released in SuspendibleThreadSet::desynchronize(). 3122 do_concurrent_mark(); 3123 ConcurrentGCBreakpoints::notify_idle_to_active(); 3124 } 3125 } 3126 3127 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3128 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3129 workers()->run_task(&rsfp_task); 3130 } 3131 3132 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3133 double remove_self_forwards_start = os::elapsedTime(); 3134 3135 remove_self_forwarding_pointers(rdcqs); 3136 _preserved_marks_set.restore(workers()); 3137 3138 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3139 } 3140 3141 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3142 if (!_evacuation_failed) { 3143 _evacuation_failed = true; 3144 } 3145 3146 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3147 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3148 } 3149 3150 bool G1ParEvacuateFollowersClosure::offer_termination() { 3151 EventGCPhaseParallel event; 3152 G1ParScanThreadState* const pss = par_scan_state(); 3153 start_term_time(); 3154 const bool res = terminator()->offer_termination(); 3155 end_term_time(); 3156 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3157 return res; 3158 } 3159 3160 void G1ParEvacuateFollowersClosure::do_void() { 3161 EventGCPhaseParallel event; 3162 G1ParScanThreadState* const pss = par_scan_state(); 3163 pss->trim_queue(); 3164 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3165 do { 3166 EventGCPhaseParallel event; 3167 pss->steal_and_trim_queue(queues()); 3168 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3169 } while (!offer_termination()); 3170 } 3171 3172 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3173 bool class_unloading_occurred) { 3174 uint num_workers = workers()->active_workers(); 3175 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3176 workers()->run_task(&unlink_task); 3177 } 3178 3179 // Clean string dedup data structures. 3180 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3181 // record the durations of the phases. Hence the almost-copy. 3182 class G1StringDedupCleaningTask : public AbstractGangTask { 3183 BoolObjectClosure* _is_alive; 3184 OopClosure* _keep_alive; 3185 G1GCPhaseTimes* _phase_times; 3186 3187 public: 3188 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3189 OopClosure* keep_alive, 3190 G1GCPhaseTimes* phase_times) : 3191 AbstractGangTask("Partial Cleaning Task"), 3192 _is_alive(is_alive), 3193 _keep_alive(keep_alive), 3194 _phase_times(phase_times) 3195 { 3196 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3197 StringDedup::gc_prologue(true); 3198 } 3199 3200 ~G1StringDedupCleaningTask() { 3201 StringDedup::gc_epilogue(); 3202 } 3203 3204 void work(uint worker_id) { 3205 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3206 { 3207 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3208 StringDedupQueue::unlink_or_oops_do(&cl); 3209 } 3210 { 3211 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3212 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3213 } 3214 } 3215 }; 3216 3217 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3218 OopClosure* keep_alive, 3219 G1GCPhaseTimes* phase_times) { 3220 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3221 workers()->run_task(&cl); 3222 } 3223 3224 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3225 private: 3226 G1RedirtyCardsQueueSet* _qset; 3227 G1CollectedHeap* _g1h; 3228 BufferNode* volatile _nodes; 3229 3230 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3231 size_t buffer_size = _qset->buffer_size(); 3232 BufferNode* next = Atomic::load(&_nodes); 3233 while (next != NULL) { 3234 BufferNode* node = next; 3235 next = Atomic::cmpxchg(&_nodes, node, node->next()); 3236 if (next == node) { 3237 cl->apply_to_buffer(node, buffer_size, worker_id); 3238 next = node->next(); 3239 } 3240 } 3241 } 3242 3243 public: 3244 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3245 AbstractGangTask("Redirty Cards"), 3246 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3247 3248 virtual void work(uint worker_id) { 3249 G1GCPhaseTimes* p = _g1h->phase_times(); 3250 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3251 3252 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3253 par_apply(&cl, worker_id); 3254 3255 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3256 } 3257 }; 3258 3259 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3260 double redirty_logged_cards_start = os::elapsedTime(); 3261 3262 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3263 workers()->run_task(&redirty_task); 3264 3265 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3266 dcq.merge_bufferlists(rdcqs); 3267 3268 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3269 } 3270 3271 // Weak Reference Processing support 3272 3273 bool G1STWIsAliveClosure::do_object_b(oop p) { 3274 // An object is reachable if it is outside the collection set, 3275 // or is inside and copied. 3276 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3277 } 3278 3279 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3280 assert(obj != NULL, "must not be NULL"); 3281 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3282 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3283 // may falsely indicate that this is not the case here: however the collection set only 3284 // contains old regions when concurrent mark is not running. 3285 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3286 } 3287 3288 // Non Copying Keep Alive closure 3289 class G1KeepAliveClosure: public OopClosure { 3290 G1CollectedHeap*_g1h; 3291 public: 3292 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3293 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3294 void do_oop(oop* p) { 3295 oop obj = *p; 3296 assert(obj != NULL, "the caller should have filtered out NULL values"); 3297 3298 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3299 if (!region_attr.is_in_cset_or_humongous()) { 3300 return; 3301 } 3302 if (region_attr.is_in_cset()) { 3303 assert( obj->is_forwarded(), "invariant" ); 3304 *p = obj->forwardee(); 3305 } else { 3306 assert(!obj->is_forwarded(), "invariant" ); 3307 assert(region_attr.is_humongous(), 3308 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3309 _g1h->set_humongous_is_live(obj); 3310 } 3311 } 3312 }; 3313 3314 // Copying Keep Alive closure - can be called from both 3315 // serial and parallel code as long as different worker 3316 // threads utilize different G1ParScanThreadState instances 3317 // and different queues. 3318 3319 class G1CopyingKeepAliveClosure: public OopClosure { 3320 G1CollectedHeap* _g1h; 3321 G1ParScanThreadState* _par_scan_state; 3322 3323 public: 3324 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3325 G1ParScanThreadState* pss): 3326 _g1h(g1h), 3327 _par_scan_state(pss) 3328 {} 3329 3330 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3331 virtual void do_oop( oop* p) { do_oop_work(p); } 3332 3333 template <class T> void do_oop_work(T* p) { 3334 oop obj = RawAccess<>::oop_load(p); 3335 3336 if (_g1h->is_in_cset_or_humongous(obj)) { 3337 // If the referent object has been forwarded (either copied 3338 // to a new location or to itself in the event of an 3339 // evacuation failure) then we need to update the reference 3340 // field and, if both reference and referent are in the G1 3341 // heap, update the RSet for the referent. 3342 // 3343 // If the referent has not been forwarded then we have to keep 3344 // it alive by policy. Therefore we have copy the referent. 3345 // 3346 // When the queue is drained (after each phase of reference processing) 3347 // the object and it's followers will be copied, the reference field set 3348 // to point to the new location, and the RSet updated. 3349 _par_scan_state->push_on_queue(ScannerTask(p)); 3350 } 3351 } 3352 }; 3353 3354 // Serial drain queue closure. Called as the 'complete_gc' 3355 // closure for each discovered list in some of the 3356 // reference processing phases. 3357 3358 class G1STWDrainQueueClosure: public VoidClosure { 3359 protected: 3360 G1CollectedHeap* _g1h; 3361 G1ParScanThreadState* _par_scan_state; 3362 3363 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3364 3365 public: 3366 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3367 _g1h(g1h), 3368 _par_scan_state(pss) 3369 { } 3370 3371 void do_void() { 3372 G1ParScanThreadState* const pss = par_scan_state(); 3373 pss->trim_queue(); 3374 } 3375 }; 3376 3377 // Parallel Reference Processing closures 3378 3379 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3380 // processing during G1 evacuation pauses. 3381 3382 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3383 private: 3384 G1CollectedHeap* _g1h; 3385 G1ParScanThreadStateSet* _pss; 3386 G1ScannerTasksQueueSet* _queues; 3387 WorkGang* _workers; 3388 3389 public: 3390 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3391 G1ParScanThreadStateSet* per_thread_states, 3392 WorkGang* workers, 3393 G1ScannerTasksQueueSet *task_queues) : 3394 _g1h(g1h), 3395 _pss(per_thread_states), 3396 _queues(task_queues), 3397 _workers(workers) 3398 { 3399 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3400 } 3401 3402 // Executes the given task using concurrent marking worker threads. 3403 virtual void execute(ProcessTask& task, uint ergo_workers); 3404 }; 3405 3406 // Gang task for possibly parallel reference processing 3407 3408 class G1STWRefProcTaskProxy: public AbstractGangTask { 3409 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3410 ProcessTask& _proc_task; 3411 G1CollectedHeap* _g1h; 3412 G1ParScanThreadStateSet* _pss; 3413 G1ScannerTasksQueueSet* _task_queues; 3414 TaskTerminator* _terminator; 3415 3416 public: 3417 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3418 G1CollectedHeap* g1h, 3419 G1ParScanThreadStateSet* per_thread_states, 3420 G1ScannerTasksQueueSet *task_queues, 3421 TaskTerminator* terminator) : 3422 AbstractGangTask("Process reference objects in parallel"), 3423 _proc_task(proc_task), 3424 _g1h(g1h), 3425 _pss(per_thread_states), 3426 _task_queues(task_queues), 3427 _terminator(terminator) 3428 {} 3429 3430 virtual void work(uint worker_id) { 3431 // The reference processing task executed by a single worker. 3432 ResourceMark rm; 3433 3434 G1STWIsAliveClosure is_alive(_g1h); 3435 3436 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3437 pss->set_ref_discoverer(NULL); 3438 3439 // Keep alive closure. 3440 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3441 3442 // Complete GC closure 3443 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3444 3445 // Call the reference processing task's work routine. 3446 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3447 3448 // Note we cannot assert that the refs array is empty here as not all 3449 // of the processing tasks (specifically phase2 - pp2_work) execute 3450 // the complete_gc closure (which ordinarily would drain the queue) so 3451 // the queue may not be empty. 3452 } 3453 }; 3454 3455 // Driver routine for parallel reference processing. 3456 // Creates an instance of the ref processing gang 3457 // task and has the worker threads execute it. 3458 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3459 assert(_workers != NULL, "Need parallel worker threads."); 3460 3461 assert(_workers->active_workers() >= ergo_workers, 3462 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3463 ergo_workers, _workers->active_workers()); 3464 TaskTerminator terminator(ergo_workers, _queues); 3465 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3466 3467 _workers->run_task(&proc_task_proxy, ergo_workers); 3468 } 3469 3470 // End of weak reference support closures 3471 3472 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3473 double ref_proc_start = os::elapsedTime(); 3474 3475 ReferenceProcessor* rp = _ref_processor_stw; 3476 assert(rp->discovery_enabled(), "should have been enabled"); 3477 3478 // Closure to test whether a referent is alive. 3479 G1STWIsAliveClosure is_alive(this); 3480 3481 // Even when parallel reference processing is enabled, the processing 3482 // of JNI refs is serial and performed serially by the current thread 3483 // rather than by a worker. The following PSS will be used for processing 3484 // JNI refs. 3485 3486 // Use only a single queue for this PSS. 3487 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3488 pss->set_ref_discoverer(NULL); 3489 assert(pss->queue_is_empty(), "pre-condition"); 3490 3491 // Keep alive closure. 3492 G1CopyingKeepAliveClosure keep_alive(this, pss); 3493 3494 // Serial Complete GC closure 3495 G1STWDrainQueueClosure drain_queue(this, pss); 3496 3497 // Setup the soft refs policy... 3498 rp->setup_policy(false); 3499 3500 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3501 3502 ReferenceProcessorStats stats; 3503 if (!rp->processing_is_mt()) { 3504 // Serial reference processing... 3505 stats = rp->process_discovered_references(&is_alive, 3506 &keep_alive, 3507 &drain_queue, 3508 NULL, 3509 pt); 3510 } else { 3511 uint no_of_gc_workers = workers()->active_workers(); 3512 3513 // Parallel reference processing 3514 assert(no_of_gc_workers <= rp->max_num_queues(), 3515 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3516 no_of_gc_workers, rp->max_num_queues()); 3517 3518 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3519 stats = rp->process_discovered_references(&is_alive, 3520 &keep_alive, 3521 &drain_queue, 3522 &par_task_executor, 3523 pt); 3524 } 3525 3526 _gc_tracer_stw->report_gc_reference_stats(stats); 3527 3528 // We have completed copying any necessary live referent objects. 3529 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3530 3531 make_pending_list_reachable(); 3532 3533 assert(!rp->discovery_enabled(), "Postcondition"); 3534 rp->verify_no_references_recorded(); 3535 3536 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3537 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3538 } 3539 3540 void G1CollectedHeap::make_pending_list_reachable() { 3541 if (collector_state()->in_concurrent_start_gc()) { 3542 oop pll_head = Universe::reference_pending_list(); 3543 if (pll_head != NULL) { 3544 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3545 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3546 } 3547 } 3548 } 3549 3550 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3551 Ticks start = Ticks::now(); 3552 per_thread_states->flush(); 3553 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds()); 3554 } 3555 3556 class G1PrepareEvacuationTask : public AbstractGangTask { 3557 class G1PrepareRegionsClosure : public HeapRegionClosure { 3558 G1CollectedHeap* _g1h; 3559 G1PrepareEvacuationTask* _parent_task; 3560 size_t _worker_humongous_total; 3561 size_t _worker_humongous_candidates; 3562 3563 bool humongous_region_is_candidate(HeapRegion* region) const { 3564 assert(region->is_starts_humongous(), "Must start a humongous object"); 3565 3566 oop obj = oop(region->bottom()); 3567 3568 // Dead objects cannot be eager reclaim candidates. Due to class 3569 // unloading it is unsafe to query their classes so we return early. 3570 if (_g1h->is_obj_dead(obj, region)) { 3571 return false; 3572 } 3573 3574 // If we do not have a complete remembered set for the region, then we can 3575 // not be sure that we have all references to it. 3576 if (!region->rem_set()->is_complete()) { 3577 return false; 3578 } 3579 // Candidate selection must satisfy the following constraints 3580 // while concurrent marking is in progress: 3581 // 3582 // * In order to maintain SATB invariants, an object must not be 3583 // reclaimed if it was allocated before the start of marking and 3584 // has not had its references scanned. Such an object must have 3585 // its references (including type metadata) scanned to ensure no 3586 // live objects are missed by the marking process. Objects 3587 // allocated after the start of concurrent marking don't need to 3588 // be scanned. 3589 // 3590 // * An object must not be reclaimed if it is on the concurrent 3591 // mark stack. Objects allocated after the start of concurrent 3592 // marking are never pushed on the mark stack. 3593 // 3594 // Nominating only objects allocated after the start of concurrent 3595 // marking is sufficient to meet both constraints. This may miss 3596 // some objects that satisfy the constraints, but the marking data 3597 // structures don't support efficiently performing the needed 3598 // additional tests or scrubbing of the mark stack. 3599 // 3600 // However, we presently only nominate is_typeArray() objects. 3601 // A humongous object containing references induces remembered 3602 // set entries on other regions. In order to reclaim such an 3603 // object, those remembered sets would need to be cleaned up. 3604 // 3605 // We also treat is_typeArray() objects specially, allowing them 3606 // to be reclaimed even if allocated before the start of 3607 // concurrent mark. For this we rely on mark stack insertion to 3608 // exclude is_typeArray() objects, preventing reclaiming an object 3609 // that is in the mark stack. We also rely on the metadata for 3610 // such objects to be built-in and so ensured to be kept live. 3611 // Frequent allocation and drop of large binary blobs is an 3612 // important use case for eager reclaim, and this special handling 3613 // may reduce needed headroom. 3614 3615 return obj->is_typeArray() && 3616 _g1h->is_potential_eager_reclaim_candidate(region); 3617 } 3618 3619 public: 3620 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) : 3621 _g1h(g1h), 3622 _parent_task(parent_task), 3623 _worker_humongous_total(0), 3624 _worker_humongous_candidates(0) { } 3625 3626 ~G1PrepareRegionsClosure() { 3627 _parent_task->add_humongous_candidates(_worker_humongous_candidates); 3628 _parent_task->add_humongous_total(_worker_humongous_total); 3629 } 3630 3631 virtual bool do_heap_region(HeapRegion* hr) { 3632 // First prepare the region for scanning 3633 _g1h->rem_set()->prepare_region_for_scan(hr); 3634 3635 // Now check if region is a humongous candidate 3636 if (!hr->is_starts_humongous()) { 3637 _g1h->register_region_with_region_attr(hr); 3638 return false; 3639 } 3640 3641 uint index = hr->hrm_index(); 3642 if (humongous_region_is_candidate(hr)) { 3643 _g1h->set_humongous_reclaim_candidate(index, true); 3644 _g1h->register_humongous_region_with_region_attr(index); 3645 _worker_humongous_candidates++; 3646 // We will later handle the remembered sets of these regions. 3647 } else { 3648 _g1h->set_humongous_reclaim_candidate(index, false); 3649 _g1h->register_region_with_region_attr(hr); 3650 } 3651 _worker_humongous_total++; 3652 3653 return false; 3654 } 3655 }; 3656 3657 G1CollectedHeap* _g1h; 3658 HeapRegionClaimer _claimer; 3659 volatile size_t _humongous_total; 3660 volatile size_t _humongous_candidates; 3661 public: 3662 G1PrepareEvacuationTask(G1CollectedHeap* g1h) : 3663 AbstractGangTask("Prepare Evacuation"), 3664 _g1h(g1h), 3665 _claimer(_g1h->workers()->active_workers()), 3666 _humongous_total(0), 3667 _humongous_candidates(0) { } 3668 3669 ~G1PrepareEvacuationTask() { 3670 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0); 3671 } 3672 3673 void work(uint worker_id) { 3674 G1PrepareRegionsClosure cl(_g1h, this); 3675 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id); 3676 } 3677 3678 void add_humongous_candidates(size_t candidates) { 3679 Atomic::add(&_humongous_candidates, candidates); 3680 } 3681 3682 void add_humongous_total(size_t total) { 3683 Atomic::add(&_humongous_total, total); 3684 } 3685 3686 size_t humongous_candidates() { 3687 return _humongous_candidates; 3688 } 3689 3690 size_t humongous_total() { 3691 return _humongous_total; 3692 } 3693 }; 3694 3695 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3696 _bytes_used_during_gc = 0; 3697 3698 _expand_heap_after_alloc_failure = true; 3699 _evacuation_failed = false; 3700 3701 // Disable the hot card cache. 3702 _hot_card_cache->reset_hot_cache_claimed_index(); 3703 _hot_card_cache->set_use_cache(false); 3704 3705 // Initialize the GC alloc regions. 3706 _allocator->init_gc_alloc_regions(evacuation_info); 3707 3708 { 3709 Ticks start = Ticks::now(); 3710 rem_set()->prepare_for_scan_heap_roots(); 3711 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3712 } 3713 3714 { 3715 G1PrepareEvacuationTask g1_prep_task(this); 3716 Tickspan task_time = run_task_timed(&g1_prep_task); 3717 3718 phase_times()->record_register_regions(task_time.seconds() * 1000.0, 3719 g1_prep_task.humongous_total(), 3720 g1_prep_task.humongous_candidates()); 3721 } 3722 3723 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3724 _preserved_marks_set.assert_empty(); 3725 3726 #if COMPILER2_OR_JVMCI 3727 DerivedPointerTable::clear(); 3728 #endif 3729 3730 // Concurrent start needs claim bits to keep track of the marked-through CLDs. 3731 if (collector_state()->in_concurrent_start_gc()) { 3732 concurrent_mark()->pre_concurrent_start(); 3733 3734 double start_clear_claimed_marks = os::elapsedTime(); 3735 3736 ClassLoaderDataGraph::clear_claimed_marks(); 3737 3738 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3739 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3740 } 3741 3742 // Should G1EvacuationFailureALot be in effect for this GC? 3743 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3744 } 3745 3746 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3747 protected: 3748 G1CollectedHeap* _g1h; 3749 G1ParScanThreadStateSet* _per_thread_states; 3750 G1ScannerTasksQueueSet* _task_queues; 3751 TaskTerminator _terminator; 3752 uint _num_workers; 3753 3754 void evacuate_live_objects(G1ParScanThreadState* pss, 3755 uint worker_id, 3756 G1GCPhaseTimes::GCParPhases objcopy_phase, 3757 G1GCPhaseTimes::GCParPhases termination_phase) { 3758 G1GCPhaseTimes* p = _g1h->phase_times(); 3759 3760 Ticks start = Ticks::now(); 3761 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase); 3762 cl.do_void(); 3763 3764 assert(pss->queue_is_empty(), "should be empty"); 3765 3766 Tickspan evac_time = (Ticks::now() - start); 3767 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3768 3769 if (termination_phase == G1GCPhaseTimes::Termination) { 3770 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3771 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3772 } else { 3773 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3774 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3775 } 3776 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3777 } 3778 3779 virtual void start_work(uint worker_id) { } 3780 3781 virtual void end_work(uint worker_id) { } 3782 3783 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3784 3785 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3786 3787 public: 3788 G1EvacuateRegionsBaseTask(const char* name, 3789 G1ParScanThreadStateSet* per_thread_states, 3790 G1ScannerTasksQueueSet* task_queues, 3791 uint num_workers) : 3792 AbstractGangTask(name), 3793 _g1h(G1CollectedHeap::heap()), 3794 _per_thread_states(per_thread_states), 3795 _task_queues(task_queues), 3796 _terminator(num_workers, _task_queues), 3797 _num_workers(num_workers) 3798 { } 3799 3800 void work(uint worker_id) { 3801 start_work(worker_id); 3802 3803 { 3804 ResourceMark rm; 3805 3806 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3807 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3808 3809 scan_roots(pss, worker_id); 3810 evacuate_live_objects(pss, worker_id); 3811 } 3812 3813 end_work(worker_id); 3814 } 3815 }; 3816 3817 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3818 G1RootProcessor* _root_processor; 3819 3820 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3821 _root_processor->evacuate_roots(pss, worker_id); 3822 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3823 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3824 } 3825 3826 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3827 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3828 } 3829 3830 void start_work(uint worker_id) { 3831 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3832 } 3833 3834 void end_work(uint worker_id) { 3835 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3836 } 3837 3838 public: 3839 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3840 G1ParScanThreadStateSet* per_thread_states, 3841 G1ScannerTasksQueueSet* task_queues, 3842 G1RootProcessor* root_processor, 3843 uint num_workers) : 3844 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3845 _root_processor(root_processor) 3846 { } 3847 }; 3848 3849 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3850 G1GCPhaseTimes* p = phase_times(); 3851 3852 { 3853 Ticks start = Ticks::now(); 3854 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3855 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3856 } 3857 3858 Tickspan task_time; 3859 const uint num_workers = workers()->active_workers(); 3860 3861 Ticks start_processing = Ticks::now(); 3862 { 3863 G1RootProcessor root_processor(this, num_workers); 3864 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3865 task_time = run_task_timed(&g1_par_task); 3866 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3867 // To extract its code root fixup time we measure total time of this scope and 3868 // subtract from the time the WorkGang task took. 3869 } 3870 Tickspan total_processing = Ticks::now() - start_processing; 3871 3872 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3873 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3874 } 3875 3876 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3877 3878 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3879 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3880 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3881 } 3882 3883 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3884 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3885 } 3886 3887 public: 3888 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3889 G1ScannerTasksQueueSet* queues, 3890 uint num_workers) : 3891 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3892 } 3893 }; 3894 3895 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3896 class G1MarkScope : public MarkScope { }; 3897 3898 Tickspan task_time; 3899 3900 Ticks start_processing = Ticks::now(); 3901 { 3902 G1MarkScope code_mark_scope; 3903 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3904 task_time = run_task_timed(&task); 3905 // See comment in evacuate_collection_set() for the reason of the scope. 3906 } 3907 Tickspan total_processing = Ticks::now() - start_processing; 3908 3909 G1GCPhaseTimes* p = phase_times(); 3910 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3911 } 3912 3913 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3914 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3915 3916 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3917 3918 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3919 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3920 3921 if (time_left_ms < 0 || 3922 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3923 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3924 _collection_set.optional_region_length(), time_left_ms); 3925 break; 3926 } 3927 3928 { 3929 Ticks start = Ticks::now(); 3930 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3931 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3932 } 3933 3934 { 3935 Ticks start = Ticks::now(); 3936 evacuate_next_optional_regions(per_thread_states); 3937 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3938 } 3939 } 3940 3941 _collection_set.abandon_optional_collection_set(per_thread_states); 3942 } 3943 3944 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3945 G1RedirtyCardsQueueSet* rdcqs, 3946 G1ParScanThreadStateSet* per_thread_states) { 3947 G1GCPhaseTimes* p = phase_times(); 3948 3949 rem_set()->cleanup_after_scan_heap_roots(); 3950 3951 // Process any discovered reference objects - we have 3952 // to do this _before_ we retire the GC alloc regions 3953 // as we may have to copy some 'reachable' referent 3954 // objects (and their reachable sub-graphs) that were 3955 // not copied during the pause. 3956 process_discovered_references(per_thread_states); 3957 3958 G1STWIsAliveClosure is_alive(this); 3959 G1KeepAliveClosure keep_alive(this); 3960 3961 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times()); 3962 3963 if (G1StringDedup::is_enabled()) { 3964 double string_dedup_time_ms = os::elapsedTime(); 3965 3966 string_dedup_cleaning(&is_alive, &keep_alive, p); 3967 3968 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3969 p->record_string_deduplication_time(string_cleanup_time_ms); 3970 } 3971 3972 _allocator->release_gc_alloc_regions(evacuation_info); 3973 3974 if (evacuation_failed()) { 3975 restore_after_evac_failure(rdcqs); 3976 3977 // Reset the G1EvacuationFailureALot counters and flags 3978 NOT_PRODUCT(reset_evacuation_should_fail();) 3979 3980 double recalculate_used_start = os::elapsedTime(); 3981 set_used(recalculate_used()); 3982 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3983 3984 if (_archive_allocator != NULL) { 3985 _archive_allocator->clear_used(); 3986 } 3987 for (uint i = 0; i < ParallelGCThreads; i++) { 3988 if (_evacuation_failed_info_array[i].has_failed()) { 3989 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3990 } 3991 } 3992 } else { 3993 // The "used" of the the collection set have already been subtracted 3994 // when they were freed. Add in the bytes used. 3995 increase_used(_bytes_used_during_gc); 3996 } 3997 3998 _preserved_marks_set.assert_empty(); 3999 4000 merge_per_thread_state_info(per_thread_states); 4001 4002 // Reset and re-enable the hot card cache. 4003 // Note the counts for the cards in the regions in the 4004 // collection set are reset when the collection set is freed. 4005 _hot_card_cache->reset_hot_cache(); 4006 _hot_card_cache->set_use_cache(true); 4007 4008 purge_code_root_memory(); 4009 4010 redirty_logged_cards(rdcqs); 4011 4012 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4013 4014 eagerly_reclaim_humongous_regions(); 4015 4016 record_obj_copy_mem_stats(); 4017 4018 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4019 evacuation_info.set_bytes_used(_bytes_used_during_gc); 4020 4021 #if COMPILER2_OR_JVMCI 4022 double start = os::elapsedTime(); 4023 DerivedPointerTable::update_pointers(); 4024 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4025 #endif 4026 policy()->print_age_table(); 4027 } 4028 4029 void G1CollectedHeap::record_obj_copy_mem_stats() { 4030 policy()->old_gen_alloc_tracker()-> 4031 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4032 4033 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4034 create_g1_evac_summary(&_old_evac_stats)); 4035 } 4036 4037 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 4038 assert(!hr->is_free(), "the region should not be free"); 4039 assert(!hr->is_empty(), "the region should not be empty"); 4040 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4041 4042 if (G1VerifyBitmaps) { 4043 MemRegion mr(hr->bottom(), hr->end()); 4044 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4045 } 4046 4047 // Clear the card counts for this region. 4048 // Note: we only need to do this if the region is not young 4049 // (since we don't refine cards in young regions). 4050 if (!hr->is_young()) { 4051 _hot_card_cache->reset_card_counts(hr); 4052 } 4053 4054 // Reset region metadata to allow reuse. 4055 hr->hr_clear(true /* clear_space */); 4056 _policy->remset_tracker()->update_at_free(hr); 4057 4058 if (free_list != NULL) { 4059 free_list->add_ordered(hr); 4060 } 4061 } 4062 4063 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4064 FreeRegionList* free_list) { 4065 assert(hr->is_humongous(), "this is only for humongous regions"); 4066 assert(free_list != NULL, "pre-condition"); 4067 hr->clear_humongous(); 4068 free_region(hr, free_list); 4069 } 4070 4071 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4072 const uint humongous_regions_removed) { 4073 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4074 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4075 _old_set.bulk_remove(old_regions_removed); 4076 _humongous_set.bulk_remove(humongous_regions_removed); 4077 } 4078 4079 } 4080 4081 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4082 assert(list != NULL, "list can't be null"); 4083 if (!list->is_empty()) { 4084 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4085 _hrm->insert_list_into_free_list(list); 4086 } 4087 } 4088 4089 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4090 decrease_used(bytes); 4091 } 4092 4093 class G1FreeCollectionSetTask : public AbstractGangTask { 4094 // Helper class to keep statistics for the collection set freeing 4095 class FreeCSetStats { 4096 size_t _before_used_bytes; // Usage in regions successfully evacutate 4097 size_t _after_used_bytes; // Usage in regions failing evacuation 4098 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old 4099 size_t _failure_used_words; // Live size in failed regions 4100 size_t _failure_waste_words; // Wasted size in failed regions 4101 size_t _rs_length; // Remembered set size 4102 uint _regions_freed; // Number of regions freed 4103 public: 4104 FreeCSetStats() : 4105 _before_used_bytes(0), 4106 _after_used_bytes(0), 4107 _bytes_allocated_in_old_since_last_gc(0), 4108 _failure_used_words(0), 4109 _failure_waste_words(0), 4110 _rs_length(0), 4111 _regions_freed(0) { } 4112 4113 void merge_stats(FreeCSetStats* other) { 4114 assert(other != NULL, "invariant"); 4115 _before_used_bytes += other->_before_used_bytes; 4116 _after_used_bytes += other->_after_used_bytes; 4117 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc; 4118 _failure_used_words += other->_failure_used_words; 4119 _failure_waste_words += other->_failure_waste_words; 4120 _rs_length += other->_rs_length; 4121 _regions_freed += other->_regions_freed; 4122 } 4123 4124 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) { 4125 evacuation_info->set_regions_freed(_regions_freed); 4126 evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4127 4128 g1h->decrement_summary_bytes(_before_used_bytes); 4129 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4130 4131 G1Policy *policy = g1h->policy(); 4132 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4133 policy->record_rs_length(_rs_length); 4134 policy->cset_regions_freed(); 4135 } 4136 4137 void account_failed_region(HeapRegion* r) { 4138 size_t used_words = r->marked_bytes() / HeapWordSize; 4139 _failure_used_words += used_words; 4140 _failure_waste_words += HeapRegion::GrainWords - used_words; 4141 _after_used_bytes += r->used(); 4142 4143 // When moving a young gen region to old gen, we "allocate" that whole 4144 // region there. This is in addition to any already evacuated objects. 4145 // Notify the policy about that. Old gen regions do not cause an 4146 // additional allocation: both the objects still in the region and the 4147 // ones already moved are accounted for elsewhere. 4148 if (r->is_young()) { 4149 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4150 } 4151 } 4152 4153 void account_evacuated_region(HeapRegion* r) { 4154 _before_used_bytes += r->used(); 4155 _regions_freed += 1; 4156 } 4157 4158 void account_rs_length(HeapRegion* r) { 4159 _rs_length += r->rem_set()->occupied(); 4160 } 4161 }; 4162 4163 // Closure applied to all regions in the collection set. 4164 class FreeCSetClosure : public HeapRegionClosure { 4165 // Helper to send JFR events for regions. 4166 class JFREventForRegion { 4167 EventGCPhaseParallel _event; 4168 public: 4169 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() { 4170 _event.set_gcId(GCId::current()); 4171 _event.set_gcWorkerId(worker_id); 4172 if (region->is_young()) { 4173 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4174 } else { 4175 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4176 } 4177 } 4178 4179 ~JFREventForRegion() { 4180 _event.commit(); 4181 } 4182 }; 4183 4184 // Helper to do timing for region work. 4185 class TimerForRegion { 4186 Tickspan& _time; 4187 Ticks _start_time; 4188 public: 4189 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { } 4190 ~TimerForRegion() { 4191 _time += Ticks::now() - _start_time; 4192 } 4193 }; 4194 4195 // FreeCSetClosure members 4196 G1CollectedHeap* _g1h; 4197 const size_t* _surviving_young_words; 4198 uint _worker_id; 4199 Tickspan _young_time; 4200 Tickspan _non_young_time; 4201 FreeCSetStats* _stats; 4202 4203 void assert_in_cset(HeapRegion* r) { 4204 assert(r->young_index_in_cset() != 0 && 4205 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(), 4206 "Young index %u is wrong for region %u of type %s with %u young regions", 4207 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length()); 4208 } 4209 4210 void handle_evacuated_region(HeapRegion* r) { 4211 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4212 stats()->account_evacuated_region(r); 4213 4214 // Free the region and and its remembered set. 4215 _g1h->free_region(r, NULL); 4216 } 4217 4218 void handle_failed_region(HeapRegion* r) { 4219 // Do some allocation statistics accounting. Regions that failed evacuation 4220 // are always made old, so there is no need to update anything in the young 4221 // gen statistics, but we need to update old gen statistics. 4222 stats()->account_failed_region(r); 4223 4224 // Update the region state due to the failed evacuation. 4225 r->handle_evacuation_failure(); 4226 4227 // Add region to old set, need to hold lock. 4228 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4229 _g1h->old_set_add(r); 4230 } 4231 4232 Tickspan& timer_for_region(HeapRegion* r) { 4233 return r->is_young() ? _young_time : _non_young_time; 4234 } 4235 4236 FreeCSetStats* stats() { 4237 return _stats; 4238 } 4239 public: 4240 FreeCSetClosure(const size_t* surviving_young_words, 4241 uint worker_id, 4242 FreeCSetStats* stats) : 4243 HeapRegionClosure(), 4244 _g1h(G1CollectedHeap::heap()), 4245 _surviving_young_words(surviving_young_words), 4246 _worker_id(worker_id), 4247 _young_time(), 4248 _non_young_time(), 4249 _stats(stats) { } 4250 4251 virtual bool do_heap_region(HeapRegion* r) { 4252 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index()); 4253 JFREventForRegion event(r, _worker_id); 4254 TimerForRegion timer(timer_for_region(r)); 4255 4256 _g1h->clear_region_attr(r); 4257 stats()->account_rs_length(r); 4258 4259 if (r->is_young()) { 4260 assert_in_cset(r); 4261 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]); 4262 } 4263 4264 if (r->evacuation_failed()) { 4265 handle_failed_region(r); 4266 } else { 4267 handle_evacuated_region(r); 4268 } 4269 assert(!_g1h->is_on_master_free_list(r), "sanity"); 4270 4271 return false; 4272 } 4273 4274 void report_timing(Tickspan parallel_time) { 4275 G1GCPhaseTimes* pt = _g1h->phase_times(); 4276 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds()); 4277 if (_young_time.value() > 0) { 4278 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds()); 4279 } 4280 if (_non_young_time.value() > 0) { 4281 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds()); 4282 } 4283 } 4284 }; 4285 4286 // G1FreeCollectionSetTask members 4287 G1CollectedHeap* _g1h; 4288 G1EvacuationInfo* _evacuation_info; 4289 FreeCSetStats* _worker_stats; 4290 HeapRegionClaimer _claimer; 4291 const size_t* _surviving_young_words; 4292 uint _active_workers; 4293 4294 FreeCSetStats* worker_stats(uint worker) { 4295 return &_worker_stats[worker]; 4296 } 4297 4298 void report_statistics() { 4299 // Merge the accounting 4300 FreeCSetStats total_stats; 4301 for (uint worker = 0; worker < _active_workers; worker++) { 4302 total_stats.merge_stats(worker_stats(worker)); 4303 } 4304 total_stats.report(_g1h, _evacuation_info); 4305 } 4306 4307 public: 4308 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) : 4309 AbstractGangTask("G1 Free Collection Set"), 4310 _g1h(G1CollectedHeap::heap()), 4311 _evacuation_info(evacuation_info), 4312 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)), 4313 _claimer(active_workers), 4314 _surviving_young_words(surviving_young_words), 4315 _active_workers(active_workers) { 4316 for (uint worker = 0; worker < active_workers; worker++) { 4317 ::new (&_worker_stats[worker]) FreeCSetStats(); 4318 } 4319 } 4320 4321 ~G1FreeCollectionSetTask() { 4322 Ticks serial_time = Ticks::now(); 4323 report_statistics(); 4324 for (uint worker = 0; worker < _active_workers; worker++) { 4325 _worker_stats[worker].~FreeCSetStats(); 4326 } 4327 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats); 4328 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0); 4329 } 4330 4331 virtual void work(uint worker_id) { 4332 EventGCPhaseParallel event; 4333 Ticks start = Ticks::now(); 4334 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id)); 4335 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id); 4336 4337 // Report the total parallel time along with some more detailed metrics. 4338 cl.report_timing(Ticks::now() - start); 4339 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet)); 4340 } 4341 }; 4342 4343 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4344 _eden.clear(); 4345 4346 // The free collections set is split up in two tasks, the first 4347 // frees the collection set and records what regions are free, 4348 // and the second one rebuilds the free list. This proved to be 4349 // more efficient than adding a sorted list to another. 4350 4351 Ticks free_cset_start_time = Ticks::now(); 4352 { 4353 uint const num_cs_regions = _collection_set.region_length(); 4354 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers()); 4355 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers); 4356 4357 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)", 4358 cl.name(), num_workers, num_cs_regions, num_regions()); 4359 workers()->run_task(&cl, num_workers); 4360 } 4361 4362 Ticks free_cset_end_time = Ticks::now(); 4363 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0); 4364 4365 // Now rebuild the free region list. 4366 hrm()->rebuild_free_list(workers()); 4367 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0); 4368 4369 collection_set->clear(); 4370 } 4371 4372 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4373 private: 4374 FreeRegionList* _free_region_list; 4375 HeapRegionSet* _proxy_set; 4376 uint _humongous_objects_reclaimed; 4377 uint _humongous_regions_reclaimed; 4378 size_t _freed_bytes; 4379 public: 4380 4381 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4382 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4383 } 4384 4385 virtual bool do_heap_region(HeapRegion* r) { 4386 if (!r->is_starts_humongous()) { 4387 return false; 4388 } 4389 4390 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4391 4392 oop obj = (oop)r->bottom(); 4393 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4394 4395 // The following checks whether the humongous object is live are sufficient. 4396 // The main additional check (in addition to having a reference from the roots 4397 // or the young gen) is whether the humongous object has a remembered set entry. 4398 // 4399 // A humongous object cannot be live if there is no remembered set for it 4400 // because: 4401 // - there can be no references from within humongous starts regions referencing 4402 // the object because we never allocate other objects into them. 4403 // (I.e. there are no intra-region references that may be missed by the 4404 // remembered set) 4405 // - as soon there is a remembered set entry to the humongous starts region 4406 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4407 // until the end of a concurrent mark. 4408 // 4409 // It is not required to check whether the object has been found dead by marking 4410 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4411 // all objects allocated during that time are considered live. 4412 // SATB marking is even more conservative than the remembered set. 4413 // So if at this point in the collection there is no remembered set entry, 4414 // nobody has a reference to it. 4415 // At the start of collection we flush all refinement logs, and remembered sets 4416 // are completely up-to-date wrt to references to the humongous object. 4417 // 4418 // Other implementation considerations: 4419 // - never consider object arrays at this time because they would pose 4420 // considerable effort for cleaning up the the remembered sets. This is 4421 // required because stale remembered sets might reference locations that 4422 // are currently allocated into. 4423 uint region_idx = r->hrm_index(); 4424 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4425 !r->rem_set()->is_empty()) { 4426 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", 4427 region_idx, 4428 (size_t)obj->size() * HeapWordSize, 4429 p2i(r->bottom()), 4430 r->rem_set()->occupied(), 4431 r->rem_set()->strong_code_roots_list_length(), 4432 next_bitmap->is_marked(r->bottom()), 4433 g1h->is_humongous_reclaim_candidate(region_idx), 4434 obj->is_typeArray() 4435 ); 4436 return false; 4437 } 4438 4439 guarantee(obj->is_typeArray(), 4440 "Only eagerly reclaiming type arrays is supported, but the object " 4441 PTR_FORMAT " is not.", p2i(r->bottom())); 4442 4443 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", 4444 region_idx, 4445 (size_t)obj->size() * HeapWordSize, 4446 p2i(r->bottom()), 4447 r->rem_set()->occupied(), 4448 r->rem_set()->strong_code_roots_list_length(), 4449 next_bitmap->is_marked(r->bottom()), 4450 g1h->is_humongous_reclaim_candidate(region_idx), 4451 obj->is_typeArray() 4452 ); 4453 4454 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4455 cm->humongous_object_eagerly_reclaimed(r); 4456 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4457 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4458 region_idx, 4459 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4460 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4461 _humongous_objects_reclaimed++; 4462 do { 4463 HeapRegion* next = g1h->next_region_in_humongous(r); 4464 _freed_bytes += r->used(); 4465 r->set_containing_set(NULL); 4466 _humongous_regions_reclaimed++; 4467 g1h->free_humongous_region(r, _free_region_list); 4468 r = next; 4469 } while (r != NULL); 4470 4471 return false; 4472 } 4473 4474 uint humongous_objects_reclaimed() { 4475 return _humongous_objects_reclaimed; 4476 } 4477 4478 uint humongous_regions_reclaimed() { 4479 return _humongous_regions_reclaimed; 4480 } 4481 4482 size_t bytes_freed() const { 4483 return _freed_bytes; 4484 } 4485 }; 4486 4487 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4488 assert_at_safepoint_on_vm_thread(); 4489 4490 if (!G1EagerReclaimHumongousObjects || 4491 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4492 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4493 return; 4494 } 4495 4496 double start_time = os::elapsedTime(); 4497 4498 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4499 4500 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4501 heap_region_iterate(&cl); 4502 4503 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4504 4505 G1HRPrinter* hrp = hr_printer(); 4506 if (hrp->is_active()) { 4507 FreeRegionListIterator iter(&local_cleanup_list); 4508 while (iter.more_available()) { 4509 HeapRegion* hr = iter.get_next(); 4510 hrp->cleanup(hr); 4511 } 4512 } 4513 4514 prepend_to_freelist(&local_cleanup_list); 4515 decrement_summary_bytes(cl.bytes_freed()); 4516 4517 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4518 cl.humongous_objects_reclaimed()); 4519 } 4520 4521 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4522 public: 4523 virtual bool do_heap_region(HeapRegion* r) { 4524 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4525 G1CollectedHeap::heap()->clear_region_attr(r); 4526 r->clear_young_index_in_cset(); 4527 return false; 4528 } 4529 }; 4530 4531 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4532 G1AbandonCollectionSetClosure cl; 4533 collection_set_iterate_all(&cl); 4534 4535 collection_set->clear(); 4536 collection_set->stop_incremental_building(); 4537 } 4538 4539 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4540 return _allocator->is_retained_old_region(hr); 4541 } 4542 4543 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4544 _eden.add(hr); 4545 _policy->set_region_eden(hr); 4546 } 4547 4548 #ifdef ASSERT 4549 4550 class NoYoungRegionsClosure: public HeapRegionClosure { 4551 private: 4552 bool _success; 4553 public: 4554 NoYoungRegionsClosure() : _success(true) { } 4555 bool do_heap_region(HeapRegion* r) { 4556 if (r->is_young()) { 4557 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4558 p2i(r->bottom()), p2i(r->end())); 4559 _success = false; 4560 } 4561 return false; 4562 } 4563 bool success() { return _success; } 4564 }; 4565 4566 bool G1CollectedHeap::check_young_list_empty() { 4567 bool ret = (young_regions_count() == 0); 4568 4569 NoYoungRegionsClosure closure; 4570 heap_region_iterate(&closure); 4571 ret = ret && closure.success(); 4572 4573 return ret; 4574 } 4575 4576 #endif // ASSERT 4577 4578 class TearDownRegionSetsClosure : public HeapRegionClosure { 4579 HeapRegionSet *_old_set; 4580 4581 public: 4582 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4583 4584 bool do_heap_region(HeapRegion* r) { 4585 if (r->is_old()) { 4586 _old_set->remove(r); 4587 } else if(r->is_young()) { 4588 r->uninstall_surv_rate_group(); 4589 } else { 4590 // We ignore free regions, we'll empty the free list afterwards. 4591 // We ignore humongous and archive regions, we're not tearing down these 4592 // sets. 4593 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4594 "it cannot be another type"); 4595 } 4596 return false; 4597 } 4598 4599 ~TearDownRegionSetsClosure() { 4600 assert(_old_set->is_empty(), "post-condition"); 4601 } 4602 }; 4603 4604 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4605 assert_at_safepoint_on_vm_thread(); 4606 4607 if (!free_list_only) { 4608 TearDownRegionSetsClosure cl(&_old_set); 4609 heap_region_iterate(&cl); 4610 4611 // Note that emptying the _young_list is postponed and instead done as 4612 // the first step when rebuilding the regions sets again. The reason for 4613 // this is that during a full GC string deduplication needs to know if 4614 // a collected region was young or old when the full GC was initiated. 4615 } 4616 _hrm->remove_all_free_regions(); 4617 } 4618 4619 void G1CollectedHeap::increase_used(size_t bytes) { 4620 _summary_bytes_used += bytes; 4621 } 4622 4623 void G1CollectedHeap::decrease_used(size_t bytes) { 4624 assert(_summary_bytes_used >= bytes, 4625 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4626 _summary_bytes_used, bytes); 4627 _summary_bytes_used -= bytes; 4628 } 4629 4630 void G1CollectedHeap::set_used(size_t bytes) { 4631 _summary_bytes_used = bytes; 4632 } 4633 4634 class RebuildRegionSetsClosure : public HeapRegionClosure { 4635 private: 4636 bool _free_list_only; 4637 4638 HeapRegionSet* _old_set; 4639 HeapRegionManager* _hrm; 4640 4641 size_t _total_used; 4642 4643 public: 4644 RebuildRegionSetsClosure(bool free_list_only, 4645 HeapRegionSet* old_set, 4646 HeapRegionManager* hrm) : 4647 _free_list_only(free_list_only), 4648 _old_set(old_set), _hrm(hrm), _total_used(0) { 4649 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4650 if (!free_list_only) { 4651 assert(_old_set->is_empty(), "pre-condition"); 4652 } 4653 } 4654 4655 bool do_heap_region(HeapRegion* r) { 4656 if (r->is_empty()) { 4657 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4658 // Add free regions to the free list 4659 r->set_free(); 4660 _hrm->insert_into_free_list(r); 4661 } else if (!_free_list_only) { 4662 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4663 4664 if (r->is_archive() || r->is_humongous()) { 4665 // We ignore archive and humongous regions. We left these sets unchanged. 4666 } else { 4667 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4668 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4669 r->move_to_old(); 4670 _old_set->add(r); 4671 } 4672 _total_used += r->used(); 4673 } 4674 4675 return false; 4676 } 4677 4678 size_t total_used() { 4679 return _total_used; 4680 } 4681 }; 4682 4683 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4684 assert_at_safepoint_on_vm_thread(); 4685 4686 if (!free_list_only) { 4687 _eden.clear(); 4688 _survivor.clear(); 4689 } 4690 4691 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4692 heap_region_iterate(&cl); 4693 4694 if (!free_list_only) { 4695 set_used(cl.total_used()); 4696 if (_archive_allocator != NULL) { 4697 _archive_allocator->clear_used(); 4698 } 4699 } 4700 assert_used_and_recalculate_used_equal(this); 4701 } 4702 4703 // Methods for the mutator alloc region 4704 4705 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4706 bool force, 4707 uint node_index) { 4708 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4709 bool should_allocate = policy()->should_allocate_mutator_region(); 4710 if (force || should_allocate) { 4711 HeapRegion* new_alloc_region = new_region(word_size, 4712 HeapRegionType::Eden, 4713 false /* do_expand */, 4714 node_index); 4715 if (new_alloc_region != NULL) { 4716 set_region_short_lived_locked(new_alloc_region); 4717 _hr_printer.alloc(new_alloc_region, !should_allocate); 4718 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4719 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4720 return new_alloc_region; 4721 } 4722 } 4723 return NULL; 4724 } 4725 4726 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4727 size_t allocated_bytes) { 4728 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4729 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4730 4731 collection_set()->add_eden_region(alloc_region); 4732 increase_used(allocated_bytes); 4733 _eden.add_used_bytes(allocated_bytes); 4734 _hr_printer.retire(alloc_region); 4735 4736 // We update the eden sizes here, when the region is retired, 4737 // instead of when it's allocated, since this is the point that its 4738 // used space has been recorded in _summary_bytes_used. 4739 g1mm()->update_eden_size(); 4740 } 4741 4742 // Methods for the GC alloc regions 4743 4744 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4745 if (dest.is_old()) { 4746 return true; 4747 } else { 4748 return survivor_regions_count() < policy()->max_survivor_regions(); 4749 } 4750 } 4751 4752 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4753 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4754 4755 if (!has_more_regions(dest)) { 4756 return NULL; 4757 } 4758 4759 HeapRegionType type; 4760 if (dest.is_young()) { 4761 type = HeapRegionType::Survivor; 4762 } else { 4763 type = HeapRegionType::Old; 4764 } 4765 4766 HeapRegion* new_alloc_region = new_region(word_size, 4767 type, 4768 true /* do_expand */, 4769 node_index); 4770 4771 if (new_alloc_region != NULL) { 4772 if (type.is_survivor()) { 4773 new_alloc_region->set_survivor(); 4774 _survivor.add(new_alloc_region); 4775 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4776 } else { 4777 new_alloc_region->set_old(); 4778 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4779 } 4780 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4781 register_region_with_region_attr(new_alloc_region); 4782 _hr_printer.alloc(new_alloc_region); 4783 return new_alloc_region; 4784 } 4785 return NULL; 4786 } 4787 4788 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4789 size_t allocated_bytes, 4790 G1HeapRegionAttr dest) { 4791 _bytes_used_during_gc += allocated_bytes; 4792 if (dest.is_old()) { 4793 old_set_add(alloc_region); 4794 } else { 4795 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4796 _survivor.add_used_bytes(allocated_bytes); 4797 } 4798 4799 bool const during_im = collector_state()->in_concurrent_start_gc(); 4800 if (during_im && allocated_bytes > 0) { 4801 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4802 } 4803 _hr_printer.retire(alloc_region); 4804 } 4805 4806 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4807 bool expanded = false; 4808 uint index = _hrm->find_highest_free(&expanded); 4809 4810 if (index != G1_NO_HRM_INDEX) { 4811 if (expanded) { 4812 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4813 HeapRegion::GrainWords * HeapWordSize); 4814 } 4815 return _hrm->allocate_free_regions_starting_at(index, 1); 4816 } 4817 return NULL; 4818 } 4819 4820 // Optimized nmethod scanning 4821 4822 class RegisterNMethodOopClosure: public OopClosure { 4823 G1CollectedHeap* _g1h; 4824 nmethod* _nm; 4825 4826 template <class T> void do_oop_work(T* p) { 4827 T heap_oop = RawAccess<>::oop_load(p); 4828 if (!CompressedOops::is_null(heap_oop)) { 4829 oop obj = CompressedOops::decode_not_null(heap_oop); 4830 HeapRegion* hr = _g1h->heap_region_containing(obj); 4831 assert(!hr->is_continues_humongous(), 4832 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4833 " starting at " HR_FORMAT, 4834 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4835 4836 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4837 hr->add_strong_code_root_locked(_nm); 4838 } 4839 } 4840 4841 public: 4842 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4843 _g1h(g1h), _nm(nm) {} 4844 4845 void do_oop(oop* p) { do_oop_work(p); } 4846 void do_oop(narrowOop* p) { do_oop_work(p); } 4847 }; 4848 4849 class UnregisterNMethodOopClosure: public OopClosure { 4850 G1CollectedHeap* _g1h; 4851 nmethod* _nm; 4852 4853 template <class T> void do_oop_work(T* p) { 4854 T heap_oop = RawAccess<>::oop_load(p); 4855 if (!CompressedOops::is_null(heap_oop)) { 4856 oop obj = CompressedOops::decode_not_null(heap_oop); 4857 HeapRegion* hr = _g1h->heap_region_containing(obj); 4858 assert(!hr->is_continues_humongous(), 4859 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4860 " starting at " HR_FORMAT, 4861 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4862 4863 hr->remove_strong_code_root(_nm); 4864 } 4865 } 4866 4867 public: 4868 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4869 _g1h(g1h), _nm(nm) {} 4870 4871 void do_oop(oop* p) { do_oop_work(p); } 4872 void do_oop(narrowOop* p) { do_oop_work(p); } 4873 }; 4874 4875 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4876 guarantee(nm != NULL, "sanity"); 4877 RegisterNMethodOopClosure reg_cl(this, nm); 4878 nm->oops_do(®_cl); 4879 } 4880 4881 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4882 guarantee(nm != NULL, "sanity"); 4883 UnregisterNMethodOopClosure reg_cl(this, nm); 4884 nm->oops_do(®_cl, true); 4885 } 4886 4887 void G1CollectedHeap::purge_code_root_memory() { 4888 double purge_start = os::elapsedTime(); 4889 G1CodeRootSet::purge(); 4890 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4891 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4892 } 4893 4894 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4895 G1CollectedHeap* _g1h; 4896 4897 public: 4898 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4899 _g1h(g1h) {} 4900 4901 void do_code_blob(CodeBlob* cb) { 4902 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4903 if (nm == NULL) { 4904 return; 4905 } 4906 4907 _g1h->register_nmethod(nm); 4908 } 4909 }; 4910 4911 void G1CollectedHeap::rebuild_strong_code_roots() { 4912 RebuildStrongCodeRootClosure blob_cl(this); 4913 CodeCache::blobs_do(&blob_cl); 4914 } 4915 4916 void G1CollectedHeap::initialize_serviceability() { 4917 _g1mm->initialize_serviceability(); 4918 } 4919 4920 MemoryUsage G1CollectedHeap::memory_usage() { 4921 return _g1mm->memory_usage(); 4922 } 4923 4924 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4925 return _g1mm->memory_managers(); 4926 } 4927 4928 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4929 return _g1mm->memory_pools(); 4930 }