rev 60594 : [mq]: 8252086-remove-g1rs
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 // Create space mappers. 1622 size_t page_size = actual_reserved_page_size(heap_rs); 1623 G1RegionToSpaceMapper* heap_storage = 1624 G1RegionToSpaceMapper::create_heap_mapper(heap_rs, 1625 heap_rs.size(), 1626 page_size, 1627 HeapRegion::GrainBytes, 1628 1, 1629 mtJavaHeap); 1630 if(heap_storage == NULL) { 1631 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1632 return JNI_ERR; 1633 } 1634 1635 os::trace_page_sizes("Heap", 1636 MinHeapSize, 1637 reserved_byte_size, 1638 page_size, 1639 heap_rs.base(), 1640 heap_rs.size()); 1641 heap_storage->set_mapping_changed_listener(&_listener); 1642 1643 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1644 G1RegionToSpaceMapper* bot_storage = 1645 create_aux_memory_mapper("Block Offset Table", 1646 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize), 1647 G1BlockOffsetTable::heap_map_factor()); 1648 1649 G1RegionToSpaceMapper* cardtable_storage = 1650 create_aux_memory_mapper("Card Table", 1651 G1CardTable::compute_size(heap_rs.size() / HeapWordSize), 1652 G1CardTable::heap_map_factor()); 1653 1654 G1RegionToSpaceMapper* card_counts_storage = 1655 create_aux_memory_mapper("Card Counts Table", 1656 G1CardCounts::compute_size(heap_rs.size() / HeapWordSize), 1657 G1CardCounts::heap_map_factor()); 1658 1659 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size()); 1660 G1RegionToSpaceMapper* prev_bitmap_storage = 1661 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1662 G1RegionToSpaceMapper* next_bitmap_storage = 1663 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1664 1665 _hrm = HeapRegionManager::create_manager(this); 1666 1667 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1668 _card_table->initialize(cardtable_storage); 1669 1670 // Do later initialization work for concurrent refinement. 1671 _hot_card_cache->initialize(card_counts_storage); 1672 1673 // 6843694 - ensure that the maximum region index can fit 1674 // in the remembered set structures. 1675 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1676 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1677 1678 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1679 // start within the first card. 1680 guarantee(heap_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1681 // Also create a G1 rem set. 1682 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1683 _rem_set->initialize(max_regions()); 1684 1685 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1686 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1687 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1688 "too many cards per region"); 1689 1690 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1691 1692 _bot = new G1BlockOffsetTable(reserved(), bot_storage); 1693 1694 { 1695 size_t granularity = HeapRegion::GrainBytes; 1696 1697 _region_attr.initialize(reserved(), granularity); 1698 _humongous_reclaim_candidates.initialize(reserved(), granularity); 1699 } 1700 1701 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1702 true /* are_GC_task_threads */, 1703 false /* are_ConcurrentGC_threads */); 1704 if (_workers == NULL) { 1705 return JNI_ENOMEM; 1706 } 1707 _workers->initialize_workers(); 1708 1709 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1710 1711 // Create the G1ConcurrentMark data structure and thread. 1712 // (Must do this late, so that "max_regions" is defined.) 1713 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1714 _cm_thread = _cm->cm_thread(); 1715 1716 // Now expand into the initial heap size. 1717 if (!expand(init_byte_size, _workers)) { 1718 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1719 return JNI_ENOMEM; 1720 } 1721 1722 // Perform any initialization actions delegated to the policy. 1723 policy()->init(this, &_collection_set); 1724 1725 jint ecode = initialize_concurrent_refinement(); 1726 if (ecode != JNI_OK) { 1727 return ecode; 1728 } 1729 1730 ecode = initialize_young_gen_sampling_thread(); 1731 if (ecode != JNI_OK) { 1732 return ecode; 1733 } 1734 1735 { 1736 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1737 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1738 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1739 } 1740 1741 // Here we allocate the dummy HeapRegion that is required by the 1742 // G1AllocRegion class. 1743 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1744 1745 // We'll re-use the same region whether the alloc region will 1746 // require BOT updates or not and, if it doesn't, then a non-young 1747 // region will complain that it cannot support allocations without 1748 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1749 dummy_region->set_eden(); 1750 // Make sure it's full. 1751 dummy_region->set_top(dummy_region->end()); 1752 G1AllocRegion::setup(this, dummy_region); 1753 1754 _allocator->init_mutator_alloc_regions(); 1755 1756 // Do create of the monitoring and management support so that 1757 // values in the heap have been properly initialized. 1758 _g1mm = new G1MonitoringSupport(this); 1759 1760 G1StringDedup::initialize(); 1761 1762 _preserved_marks_set.init(ParallelGCThreads); 1763 1764 _collection_set.initialize(max_regions()); 1765 1766 G1InitLogger::print(); 1767 1768 return JNI_OK; 1769 } 1770 1771 void G1CollectedHeap::stop() { 1772 // Stop all concurrent threads. We do this to make sure these threads 1773 // do not continue to execute and access resources (e.g. logging) 1774 // that are destroyed during shutdown. 1775 _cr->stop(); 1776 _young_gen_sampling_thread->stop(); 1777 _cm_thread->stop(); 1778 if (G1StringDedup::is_enabled()) { 1779 G1StringDedup::stop(); 1780 } 1781 } 1782 1783 void G1CollectedHeap::safepoint_synchronize_begin() { 1784 SuspendibleThreadSet::synchronize(); 1785 } 1786 1787 void G1CollectedHeap::safepoint_synchronize_end() { 1788 SuspendibleThreadSet::desynchronize(); 1789 } 1790 1791 void G1CollectedHeap::post_initialize() { 1792 CollectedHeap::post_initialize(); 1793 ref_processing_init(); 1794 } 1795 1796 void G1CollectedHeap::ref_processing_init() { 1797 // Reference processing in G1 currently works as follows: 1798 // 1799 // * There are two reference processor instances. One is 1800 // used to record and process discovered references 1801 // during concurrent marking; the other is used to 1802 // record and process references during STW pauses 1803 // (both full and incremental). 1804 // * Both ref processors need to 'span' the entire heap as 1805 // the regions in the collection set may be dotted around. 1806 // 1807 // * For the concurrent marking ref processor: 1808 // * Reference discovery is enabled at concurrent start. 1809 // * Reference discovery is disabled and the discovered 1810 // references processed etc during remarking. 1811 // * Reference discovery is MT (see below). 1812 // * Reference discovery requires a barrier (see below). 1813 // * Reference processing may or may not be MT 1814 // (depending on the value of ParallelRefProcEnabled 1815 // and ParallelGCThreads). 1816 // * A full GC disables reference discovery by the CM 1817 // ref processor and abandons any entries on it's 1818 // discovered lists. 1819 // 1820 // * For the STW processor: 1821 // * Non MT discovery is enabled at the start of a full GC. 1822 // * Processing and enqueueing during a full GC is non-MT. 1823 // * During a full GC, references are processed after marking. 1824 // 1825 // * Discovery (may or may not be MT) is enabled at the start 1826 // of an incremental evacuation pause. 1827 // * References are processed near the end of a STW evacuation pause. 1828 // * For both types of GC: 1829 // * Discovery is atomic - i.e. not concurrent. 1830 // * Reference discovery will not need a barrier. 1831 1832 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1833 1834 // Concurrent Mark ref processor 1835 _ref_processor_cm = 1836 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1837 mt_processing, // mt processing 1838 ParallelGCThreads, // degree of mt processing 1839 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1840 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1841 false, // Reference discovery is not atomic 1842 &_is_alive_closure_cm, // is alive closure 1843 true); // allow changes to number of processing threads 1844 1845 // STW ref processor 1846 _ref_processor_stw = 1847 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1848 mt_processing, // mt processing 1849 ParallelGCThreads, // degree of mt processing 1850 (ParallelGCThreads > 1), // mt discovery 1851 ParallelGCThreads, // degree of mt discovery 1852 true, // Reference discovery is atomic 1853 &_is_alive_closure_stw, // is alive closure 1854 true); // allow changes to number of processing threads 1855 } 1856 1857 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1858 return &_soft_ref_policy; 1859 } 1860 1861 size_t G1CollectedHeap::capacity() const { 1862 return _hrm->length() * HeapRegion::GrainBytes; 1863 } 1864 1865 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1866 return _hrm->total_free_bytes(); 1867 } 1868 1869 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1870 _hot_card_cache->drain(cl, worker_id); 1871 } 1872 1873 // Computes the sum of the storage used by the various regions. 1874 size_t G1CollectedHeap::used() const { 1875 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1876 if (_archive_allocator != NULL) { 1877 result += _archive_allocator->used(); 1878 } 1879 return result; 1880 } 1881 1882 size_t G1CollectedHeap::used_unlocked() const { 1883 return _summary_bytes_used; 1884 } 1885 1886 class SumUsedClosure: public HeapRegionClosure { 1887 size_t _used; 1888 public: 1889 SumUsedClosure() : _used(0) {} 1890 bool do_heap_region(HeapRegion* r) { 1891 _used += r->used(); 1892 return false; 1893 } 1894 size_t result() { return _used; } 1895 }; 1896 1897 size_t G1CollectedHeap::recalculate_used() const { 1898 SumUsedClosure blk; 1899 heap_region_iterate(&blk); 1900 return blk.result(); 1901 } 1902 1903 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1904 switch (cause) { 1905 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1906 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1907 case GCCause::_wb_conc_mark: return true; 1908 default : return false; 1909 } 1910 } 1911 1912 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1913 switch (cause) { 1914 case GCCause::_g1_humongous_allocation: return true; 1915 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1916 case GCCause::_wb_breakpoint: return true; 1917 default: return is_user_requested_concurrent_full_gc(cause); 1918 } 1919 } 1920 1921 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 1922 if (policy()->force_upgrade_to_full()) { 1923 return true; 1924 } else if (should_do_concurrent_full_gc(_gc_cause)) { 1925 return false; 1926 } else if (has_regions_left_for_allocation()) { 1927 return false; 1928 } else { 1929 return true; 1930 } 1931 } 1932 1933 #ifndef PRODUCT 1934 void G1CollectedHeap::allocate_dummy_regions() { 1935 // Let's fill up most of the region 1936 size_t word_size = HeapRegion::GrainWords - 1024; 1937 // And as a result the region we'll allocate will be humongous. 1938 guarantee(is_humongous(word_size), "sanity"); 1939 1940 // _filler_array_max_size is set to humongous object threshold 1941 // but temporarily change it to use CollectedHeap::fill_with_object(). 1942 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size); 1943 1944 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1945 // Let's use the existing mechanism for the allocation 1946 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 1947 if (dummy_obj != NULL) { 1948 MemRegion mr(dummy_obj, word_size); 1949 CollectedHeap::fill_with_object(mr); 1950 } else { 1951 // If we can't allocate once, we probably cannot allocate 1952 // again. Let's get out of the loop. 1953 break; 1954 } 1955 } 1956 } 1957 #endif // !PRODUCT 1958 1959 void G1CollectedHeap::increment_old_marking_cycles_started() { 1960 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 1961 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 1962 "Wrong marking cycle count (started: %d, completed: %d)", 1963 _old_marking_cycles_started, _old_marking_cycles_completed); 1964 1965 _old_marking_cycles_started++; 1966 } 1967 1968 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent, 1969 bool whole_heap_examined) { 1970 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 1971 1972 // We assume that if concurrent == true, then the caller is a 1973 // concurrent thread that was joined the Suspendible Thread 1974 // Set. If there's ever a cheap way to check this, we should add an 1975 // assert here. 1976 1977 // Given that this method is called at the end of a Full GC or of a 1978 // concurrent cycle, and those can be nested (i.e., a Full GC can 1979 // interrupt a concurrent cycle), the number of full collections 1980 // completed should be either one (in the case where there was no 1981 // nesting) or two (when a Full GC interrupted a concurrent cycle) 1982 // behind the number of full collections started. 1983 1984 // This is the case for the inner caller, i.e. a Full GC. 1985 assert(concurrent || 1986 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 1987 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 1988 "for inner caller (Full GC): _old_marking_cycles_started = %u " 1989 "is inconsistent with _old_marking_cycles_completed = %u", 1990 _old_marking_cycles_started, _old_marking_cycles_completed); 1991 1992 // This is the case for the outer caller, i.e. the concurrent cycle. 1993 assert(!concurrent || 1994 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 1995 "for outer caller (concurrent cycle): " 1996 "_old_marking_cycles_started = %u " 1997 "is inconsistent with _old_marking_cycles_completed = %u", 1998 _old_marking_cycles_started, _old_marking_cycles_completed); 1999 2000 _old_marking_cycles_completed += 1; 2001 if (whole_heap_examined) { 2002 // Signal that we have completed a visit to all live objects. 2003 record_whole_heap_examined_timestamp(); 2004 } 2005 2006 // We need to clear the "in_progress" flag in the CM thread before 2007 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2008 // is set) so that if a waiter requests another System.gc() it doesn't 2009 // incorrectly see that a marking cycle is still in progress. 2010 if (concurrent) { 2011 _cm_thread->set_idle(); 2012 } 2013 2014 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 2015 // for a full GC to finish that their wait is over. 2016 ml.notify_all(); 2017 } 2018 2019 void G1CollectedHeap::collect(GCCause::Cause cause) { 2020 try_collect(cause); 2021 } 2022 2023 // Return true if (x < y) with allowance for wraparound. 2024 static bool gc_counter_less_than(uint x, uint y) { 2025 return (x - y) > (UINT_MAX/2); 2026 } 2027 2028 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 2029 // Macro so msg printing is format-checked. 2030 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 2031 do { \ 2032 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 2033 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 2034 ResourceMark rm; /* For thread name. */ \ 2035 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 2036 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 2037 Thread::current()->name(), \ 2038 GCCause::to_string(cause)); \ 2039 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 2040 } \ 2041 } while (0) 2042 2043 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 2044 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 2045 2046 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 2047 uint gc_counter, 2048 uint old_marking_started_before) { 2049 assert_heap_not_locked(); 2050 assert(should_do_concurrent_full_gc(cause), 2051 "Non-concurrent cause %s", GCCause::to_string(cause)); 2052 2053 for (uint i = 1; true; ++i) { 2054 // Try to schedule concurrent start evacuation pause that will 2055 // start a concurrent cycle. 2056 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 2057 VM_G1TryInitiateConcMark op(gc_counter, 2058 cause, 2059 policy()->max_pause_time_ms()); 2060 VMThread::execute(&op); 2061 2062 // Request is trivially finished. 2063 if (cause == GCCause::_g1_periodic_collection) { 2064 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 2065 return op.gc_succeeded(); 2066 } 2067 2068 // If VMOp skipped initiating concurrent marking cycle because 2069 // we're terminating, then we're done. 2070 if (op.terminating()) { 2071 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 2072 return false; 2073 } 2074 2075 // Lock to get consistent set of values. 2076 uint old_marking_started_after; 2077 uint old_marking_completed_after; 2078 { 2079 MutexLocker ml(Heap_lock); 2080 // Update gc_counter for retrying VMOp if needed. Captured here to be 2081 // consistent with the values we use below for termination tests. If 2082 // a retry is needed after a possible wait, and another collection 2083 // occurs in the meantime, it will cause our retry to be skipped and 2084 // we'll recheck for termination with updated conditions from that 2085 // more recent collection. That's what we want, rather than having 2086 // our retry possibly perform an unnecessary collection. 2087 gc_counter = total_collections(); 2088 old_marking_started_after = _old_marking_cycles_started; 2089 old_marking_completed_after = _old_marking_cycles_completed; 2090 } 2091 2092 if (cause == GCCause::_wb_breakpoint) { 2093 if (op.gc_succeeded()) { 2094 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2095 return true; 2096 } 2097 // When _wb_breakpoint there can't be another cycle or deferred. 2098 assert(!op.cycle_already_in_progress(), "invariant"); 2099 assert(!op.whitebox_attached(), "invariant"); 2100 // Concurrent cycle attempt might have been cancelled by some other 2101 // collection, so retry. Unlike other cases below, we want to retry 2102 // even if cancelled by a STW full collection, because we really want 2103 // to start a concurrent cycle. 2104 if (old_marking_started_before != old_marking_started_after) { 2105 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 2106 old_marking_started_before = old_marking_started_after; 2107 } 2108 } else if (!GCCause::is_user_requested_gc(cause)) { 2109 // For an "automatic" (not user-requested) collection, we just need to 2110 // ensure that progress is made. 2111 // 2112 // Request is finished if any of 2113 // (1) the VMOp successfully performed a GC, 2114 // (2) a concurrent cycle was already in progress, 2115 // (3) whitebox is controlling concurrent cycles, 2116 // (4) a new cycle was started (by this thread or some other), or 2117 // (5) a Full GC was performed. 2118 // Cases (4) and (5) are detected together by a change to 2119 // _old_marking_cycles_started. 2120 // 2121 // Note that (1) does not imply (4). If we're still in the mixed 2122 // phase of an earlier concurrent collection, the request to make the 2123 // collection a concurrent start won't be honored. If we don't check for 2124 // both conditions we'll spin doing back-to-back collections. 2125 if (op.gc_succeeded() || 2126 op.cycle_already_in_progress() || 2127 op.whitebox_attached() || 2128 (old_marking_started_before != old_marking_started_after)) { 2129 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2130 return true; 2131 } 2132 } else { // User-requested GC. 2133 // For a user-requested collection, we want to ensure that a complete 2134 // full collection has been performed before returning, but without 2135 // waiting for more than needed. 2136 2137 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 2138 // new cycle was started. That's good, because it's not clear what we 2139 // should do otherwise. Trying again just does back to back GCs. 2140 // Can't wait for someone else to start a cycle. And returning fails 2141 // to meet the goal of ensuring a full collection was performed. 2142 assert(!op.gc_succeeded() || 2143 (old_marking_started_before != old_marking_started_after), 2144 "invariant: succeeded %s, started before %u, started after %u", 2145 BOOL_TO_STR(op.gc_succeeded()), 2146 old_marking_started_before, old_marking_started_after); 2147 2148 // Request is finished if a full collection (concurrent or stw) 2149 // was started after this request and has completed, e.g. 2150 // started_before < completed_after. 2151 if (gc_counter_less_than(old_marking_started_before, 2152 old_marking_completed_after)) { 2153 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2154 return true; 2155 } 2156 2157 if (old_marking_started_after != old_marking_completed_after) { 2158 // If there is an in-progress cycle (possibly started by us), then 2159 // wait for that cycle to complete, e.g. 2160 // while completed_now < started_after. 2161 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2162 MonitorLocker ml(G1OldGCCount_lock); 2163 while (gc_counter_less_than(_old_marking_cycles_completed, 2164 old_marking_started_after)) { 2165 ml.wait(); 2166 } 2167 // Request is finished if the collection we just waited for was 2168 // started after this request. 2169 if (old_marking_started_before != old_marking_started_after) { 2170 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2171 return true; 2172 } 2173 } 2174 2175 // If VMOp was successful then it started a new cycle that the above 2176 // wait &etc should have recognized as finishing this request. This 2177 // differs from a non-user-request, where gc_succeeded does not imply 2178 // a new cycle was started. 2179 assert(!op.gc_succeeded(), "invariant"); 2180 2181 if (op.cycle_already_in_progress()) { 2182 // If VMOp failed because a cycle was already in progress, it 2183 // is now complete. But it didn't finish this user-requested 2184 // GC, so try again. 2185 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2186 continue; 2187 } else if (op.whitebox_attached()) { 2188 // If WhiteBox wants control, wait for notification of a state 2189 // change in the controller, then try again. Don't wait for 2190 // release of control, since collections may complete while in 2191 // control. Note: This won't recognize a STW full collection 2192 // while waiting; we can't wait on multiple monitors. 2193 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 2194 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 2195 if (ConcurrentGCBreakpoints::is_controlled()) { 2196 ml.wait(); 2197 } 2198 continue; 2199 } 2200 } 2201 2202 // Collection failed and should be retried. 2203 assert(op.transient_failure(), "invariant"); 2204 2205 if (GCLocker::is_active_and_needs_gc()) { 2206 // If GCLocker is active, wait until clear before retrying. 2207 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2208 GCLocker::stall_until_clear(); 2209 } 2210 2211 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2212 } 2213 } 2214 2215 bool G1CollectedHeap::try_collect(GCCause::Cause cause) { 2216 assert_heap_not_locked(); 2217 2218 // Lock to get consistent set of values. 2219 uint gc_count_before; 2220 uint full_gc_count_before; 2221 uint old_marking_started_before; 2222 { 2223 MutexLocker ml(Heap_lock); 2224 gc_count_before = total_collections(); 2225 full_gc_count_before = total_full_collections(); 2226 old_marking_started_before = _old_marking_cycles_started; 2227 } 2228 2229 if (should_do_concurrent_full_gc(cause)) { 2230 return try_collect_concurrently(cause, 2231 gc_count_before, 2232 old_marking_started_before); 2233 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2234 // Indicate failure to be consistent with VMOp failure due to 2235 // another collection slipping in after our gc_count but before 2236 // our request is processed. 2237 return false; 2238 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2239 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2240 2241 // Schedule a standard evacuation pause. We're setting word_size 2242 // to 0 which means that we are not requesting a post-GC allocation. 2243 VM_G1CollectForAllocation op(0, /* word_size */ 2244 gc_count_before, 2245 cause, 2246 policy()->max_pause_time_ms()); 2247 VMThread::execute(&op); 2248 return op.gc_succeeded(); 2249 } else { 2250 // Schedule a Full GC. 2251 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2252 VMThread::execute(&op); 2253 return op.gc_succeeded(); 2254 } 2255 } 2256 2257 bool G1CollectedHeap::is_in(const void* p) const { 2258 if (_hrm->reserved().contains(p)) { 2259 // Given that we know that p is in the reserved space, 2260 // heap_region_containing() should successfully 2261 // return the containing region. 2262 HeapRegion* hr = heap_region_containing(p); 2263 return hr->is_in(p); 2264 } else { 2265 return false; 2266 } 2267 } 2268 2269 #ifdef ASSERT 2270 bool G1CollectedHeap::is_in_exact(const void* p) const { 2271 bool contains = reserved().contains(p); 2272 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2273 if (contains && available) { 2274 return true; 2275 } else { 2276 return false; 2277 } 2278 } 2279 #endif 2280 2281 // Iteration functions. 2282 2283 // Iterates an ObjectClosure over all objects within a HeapRegion. 2284 2285 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2286 ObjectClosure* _cl; 2287 public: 2288 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2289 bool do_heap_region(HeapRegion* r) { 2290 if (!r->is_continues_humongous()) { 2291 r->object_iterate(_cl); 2292 } 2293 return false; 2294 } 2295 }; 2296 2297 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2298 IterateObjectClosureRegionClosure blk(cl); 2299 heap_region_iterate(&blk); 2300 } 2301 2302 class G1ParallelObjectIterator : public ParallelObjectIterator { 2303 private: 2304 G1CollectedHeap* _heap; 2305 HeapRegionClaimer _claimer; 2306 2307 public: 2308 G1ParallelObjectIterator(uint thread_num) : 2309 _heap(G1CollectedHeap::heap()), 2310 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {} 2311 2312 virtual void object_iterate(ObjectClosure* cl, uint worker_id) { 2313 _heap->object_iterate_parallel(cl, worker_id, &_claimer); 2314 } 2315 }; 2316 2317 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) { 2318 return new G1ParallelObjectIterator(thread_num); 2319 } 2320 2321 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) { 2322 IterateObjectClosureRegionClosure blk(cl); 2323 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id); 2324 } 2325 2326 void G1CollectedHeap::keep_alive(oop obj) { 2327 G1BarrierSet::enqueue(obj); 2328 } 2329 2330 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2331 _hrm->iterate(cl); 2332 } 2333 2334 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2335 HeapRegionClaimer *hrclaimer, 2336 uint worker_id) const { 2337 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2338 } 2339 2340 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2341 HeapRegionClaimer *hrclaimer) const { 2342 _hrm->par_iterate(cl, hrclaimer, 0); 2343 } 2344 2345 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2346 _collection_set.iterate(cl); 2347 } 2348 2349 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2350 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers()); 2351 } 2352 2353 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2354 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2355 } 2356 2357 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2358 HeapRegion* hr = heap_region_containing(addr); 2359 return hr->block_start(addr); 2360 } 2361 2362 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2363 HeapRegion* hr = heap_region_containing(addr); 2364 return hr->block_is_obj(addr); 2365 } 2366 2367 bool G1CollectedHeap::supports_tlab_allocation() const { 2368 return true; 2369 } 2370 2371 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2372 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2373 } 2374 2375 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2376 return _eden.length() * HeapRegion::GrainBytes; 2377 } 2378 2379 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2380 // must be equal to the humongous object limit. 2381 size_t G1CollectedHeap::max_tlab_size() const { 2382 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2383 } 2384 2385 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2386 return _allocator->unsafe_max_tlab_alloc(); 2387 } 2388 2389 size_t G1CollectedHeap::max_capacity() const { 2390 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2391 } 2392 2393 void G1CollectedHeap::deduplicate_string(oop str) { 2394 assert(java_lang_String::is_instance(str), "invariant"); 2395 2396 if (G1StringDedup::is_enabled()) { 2397 G1StringDedup::deduplicate(str); 2398 } 2399 } 2400 2401 void G1CollectedHeap::prepare_for_verify() { 2402 _verifier->prepare_for_verify(); 2403 } 2404 2405 void G1CollectedHeap::verify(VerifyOption vo) { 2406 _verifier->verify(vo); 2407 } 2408 2409 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2410 return true; 2411 } 2412 2413 bool G1CollectedHeap::is_heterogeneous_heap() const { 2414 return G1Arguments::is_heterogeneous_heap(); 2415 } 2416 2417 class PrintRegionClosure: public HeapRegionClosure { 2418 outputStream* _st; 2419 public: 2420 PrintRegionClosure(outputStream* st) : _st(st) {} 2421 bool do_heap_region(HeapRegion* r) { 2422 r->print_on(_st); 2423 return false; 2424 } 2425 }; 2426 2427 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2428 const HeapRegion* hr, 2429 const VerifyOption vo) const { 2430 switch (vo) { 2431 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2432 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2433 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2434 default: ShouldNotReachHere(); 2435 } 2436 return false; // keep some compilers happy 2437 } 2438 2439 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2440 const VerifyOption vo) const { 2441 switch (vo) { 2442 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2443 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2444 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2445 default: ShouldNotReachHere(); 2446 } 2447 return false; // keep some compilers happy 2448 } 2449 2450 void G1CollectedHeap::print_heap_regions() const { 2451 LogTarget(Trace, gc, heap, region) lt; 2452 if (lt.is_enabled()) { 2453 LogStream ls(lt); 2454 print_regions_on(&ls); 2455 } 2456 } 2457 2458 void G1CollectedHeap::print_on(outputStream* st) const { 2459 st->print(" %-20s", "garbage-first heap"); 2460 if (_hrm != NULL) { 2461 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2462 capacity()/K, used_unlocked()/K); 2463 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2464 p2i(_hrm->reserved().start()), 2465 p2i(_hrm->reserved().end())); 2466 } 2467 st->cr(); 2468 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2469 uint young_regions = young_regions_count(); 2470 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2471 (size_t) young_regions * HeapRegion::GrainBytes / K); 2472 uint survivor_regions = survivor_regions_count(); 2473 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2474 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2475 st->cr(); 2476 if (_numa->is_enabled()) { 2477 uint num_nodes = _numa->num_active_nodes(); 2478 st->print(" remaining free region(s) on each NUMA node: "); 2479 const int* node_ids = _numa->node_ids(); 2480 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2481 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0); 2482 st->print("%d=%u ", node_ids[node_index], num_free_regions); 2483 } 2484 st->cr(); 2485 } 2486 MetaspaceUtils::print_on(st); 2487 } 2488 2489 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2490 if (_hrm == NULL) { 2491 return; 2492 } 2493 2494 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2495 "HS=humongous(starts), HC=humongous(continues), " 2496 "CS=collection set, F=free, " 2497 "OA=open archive, CA=closed archive, " 2498 "TAMS=top-at-mark-start (previous, next)"); 2499 PrintRegionClosure blk(st); 2500 heap_region_iterate(&blk); 2501 } 2502 2503 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2504 print_on(st); 2505 2506 // Print the per-region information. 2507 if (_hrm != NULL) { 2508 st->cr(); 2509 print_regions_on(st); 2510 } 2511 } 2512 2513 void G1CollectedHeap::print_on_error(outputStream* st) const { 2514 this->CollectedHeap::print_on_error(st); 2515 2516 if (_cm != NULL) { 2517 st->cr(); 2518 _cm->print_on_error(st); 2519 } 2520 } 2521 2522 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2523 workers()->threads_do(tc); 2524 tc->do_thread(_cm_thread); 2525 _cm->threads_do(tc); 2526 _cr->threads_do(tc); 2527 tc->do_thread(_young_gen_sampling_thread); 2528 if (G1StringDedup::is_enabled()) { 2529 G1StringDedup::threads_do(tc); 2530 } 2531 } 2532 2533 void G1CollectedHeap::print_tracing_info() const { 2534 rem_set()->print_summary_info(); 2535 concurrent_mark()->print_summary_info(); 2536 } 2537 2538 #ifndef PRODUCT 2539 // Helpful for debugging RSet issues. 2540 2541 class PrintRSetsClosure : public HeapRegionClosure { 2542 private: 2543 const char* _msg; 2544 size_t _occupied_sum; 2545 2546 public: 2547 bool do_heap_region(HeapRegion* r) { 2548 HeapRegionRemSet* hrrs = r->rem_set(); 2549 size_t occupied = hrrs->occupied(); 2550 _occupied_sum += occupied; 2551 2552 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2553 if (occupied == 0) { 2554 tty->print_cr(" RSet is empty"); 2555 } else { 2556 hrrs->print(); 2557 } 2558 tty->print_cr("----------"); 2559 return false; 2560 } 2561 2562 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2563 tty->cr(); 2564 tty->print_cr("========================================"); 2565 tty->print_cr("%s", msg); 2566 tty->cr(); 2567 } 2568 2569 ~PrintRSetsClosure() { 2570 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2571 tty->print_cr("========================================"); 2572 tty->cr(); 2573 } 2574 }; 2575 2576 void G1CollectedHeap::print_cset_rsets() { 2577 PrintRSetsClosure cl("Printing CSet RSets"); 2578 collection_set_iterate_all(&cl); 2579 } 2580 2581 void G1CollectedHeap::print_all_rsets() { 2582 PrintRSetsClosure cl("Printing All RSets");; 2583 heap_region_iterate(&cl); 2584 } 2585 #endif // PRODUCT 2586 2587 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2588 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2589 } 2590 2591 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2592 2593 size_t eden_used_bytes = _eden.used_bytes(); 2594 size_t survivor_used_bytes = _survivor.used_bytes(); 2595 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2596 2597 size_t eden_capacity_bytes = 2598 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2599 2600 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2601 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2602 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2603 } 2604 2605 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2606 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2607 stats->unused(), stats->used(), stats->region_end_waste(), 2608 stats->regions_filled(), stats->direct_allocated(), 2609 stats->failure_used(), stats->failure_waste()); 2610 } 2611 2612 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2613 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2614 gc_tracer->report_gc_heap_summary(when, heap_summary); 2615 2616 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2617 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2618 } 2619 2620 void G1CollectedHeap::gc_prologue(bool full) { 2621 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2622 2623 // This summary needs to be printed before incrementing total collections. 2624 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2625 2626 // Update common counters. 2627 increment_total_collections(full /* full gc */); 2628 if (full || collector_state()->in_concurrent_start_gc()) { 2629 increment_old_marking_cycles_started(); 2630 } 2631 2632 // Fill TLAB's and such 2633 { 2634 Ticks start = Ticks::now(); 2635 ensure_parsability(true); 2636 Tickspan dt = Ticks::now() - start; 2637 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS); 2638 } 2639 2640 if (!full) { 2641 // Flush dirty card queues to qset, so later phases don't need to account 2642 // for partially filled per-thread queues and such. Not needed for full 2643 // collections, which ignore those logs. 2644 Ticks start = Ticks::now(); 2645 G1BarrierSet::dirty_card_queue_set().concatenate_logs(); 2646 Tickspan dt = Ticks::now() - start; 2647 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS); 2648 } 2649 } 2650 2651 void G1CollectedHeap::gc_epilogue(bool full) { 2652 // Update common counters. 2653 if (full) { 2654 // Update the number of full collections that have been completed. 2655 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */); 2656 } 2657 2658 // We are at the end of the GC. Total collections has already been increased. 2659 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2660 2661 // FIXME: what is this about? 2662 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2663 // is set. 2664 #if COMPILER2_OR_JVMCI 2665 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2666 #endif 2667 2668 double start = os::elapsedTime(); 2669 resize_all_tlabs(); 2670 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2671 2672 MemoryService::track_memory_usage(); 2673 // We have just completed a GC. Update the soft reference 2674 // policy with the new heap occupancy 2675 Universe::update_heap_info_at_gc(); 2676 2677 // Print NUMA statistics. 2678 _numa->print_statistics(); 2679 2680 _collection_pause_end = Ticks::now(); 2681 } 2682 2683 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2684 LogTarget(Trace, gc, heap, verify) lt; 2685 2686 if (lt.is_enabled()) { 2687 LogStream ls(lt); 2688 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2689 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2690 heap_region_iterate(&cl); 2691 } 2692 } 2693 2694 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2695 uint gc_count_before, 2696 bool* succeeded, 2697 GCCause::Cause gc_cause) { 2698 assert_heap_not_locked_and_not_at_safepoint(); 2699 VM_G1CollectForAllocation op(word_size, 2700 gc_count_before, 2701 gc_cause, 2702 policy()->max_pause_time_ms()); 2703 VMThread::execute(&op); 2704 2705 HeapWord* result = op.result(); 2706 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2707 assert(result == NULL || ret_succeeded, 2708 "the result should be NULL if the VM did not succeed"); 2709 *succeeded = ret_succeeded; 2710 2711 assert_heap_not_locked(); 2712 return result; 2713 } 2714 2715 void G1CollectedHeap::do_concurrent_mark() { 2716 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2717 if (!_cm_thread->in_progress()) { 2718 _cm_thread->set_started(); 2719 CGC_lock->notify(); 2720 } 2721 } 2722 2723 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2724 // We don't nominate objects with many remembered set entries, on 2725 // the assumption that such objects are likely still live. 2726 HeapRegionRemSet* rem_set = r->rem_set(); 2727 2728 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2729 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2730 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2731 } 2732 2733 #ifndef PRODUCT 2734 void G1CollectedHeap::verify_region_attr_remset_update() { 2735 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2736 public: 2737 virtual bool do_heap_region(HeapRegion* r) { 2738 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2739 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2740 assert(r->rem_set()->is_tracked() == needs_remset_update, 2741 "Region %u remset tracking status (%s) different to region attribute (%s)", 2742 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2743 return false; 2744 } 2745 } cl; 2746 heap_region_iterate(&cl); 2747 } 2748 #endif 2749 2750 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2751 public: 2752 bool do_heap_region(HeapRegion* hr) { 2753 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2754 hr->verify_rem_set(); 2755 } 2756 return false; 2757 } 2758 }; 2759 2760 uint G1CollectedHeap::num_task_queues() const { 2761 return _task_queues->size(); 2762 } 2763 2764 #if TASKQUEUE_STATS 2765 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2766 st->print_raw_cr("GC Task Stats"); 2767 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2768 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2769 } 2770 2771 void G1CollectedHeap::print_taskqueue_stats() const { 2772 if (!log_is_enabled(Trace, gc, task, stats)) { 2773 return; 2774 } 2775 Log(gc, task, stats) log; 2776 ResourceMark rm; 2777 LogStream ls(log.trace()); 2778 outputStream* st = &ls; 2779 2780 print_taskqueue_stats_hdr(st); 2781 2782 TaskQueueStats totals; 2783 const uint n = num_task_queues(); 2784 for (uint i = 0; i < n; ++i) { 2785 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2786 totals += task_queue(i)->stats; 2787 } 2788 st->print_raw("tot "); totals.print(st); st->cr(); 2789 2790 DEBUG_ONLY(totals.verify()); 2791 } 2792 2793 void G1CollectedHeap::reset_taskqueue_stats() { 2794 const uint n = num_task_queues(); 2795 for (uint i = 0; i < n; ++i) { 2796 task_queue(i)->stats.reset(); 2797 } 2798 } 2799 #endif // TASKQUEUE_STATS 2800 2801 void G1CollectedHeap::wait_for_root_region_scanning() { 2802 double scan_wait_start = os::elapsedTime(); 2803 // We have to wait until the CM threads finish scanning the 2804 // root regions as it's the only way to ensure that all the 2805 // objects on them have been correctly scanned before we start 2806 // moving them during the GC. 2807 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2808 double wait_time_ms = 0.0; 2809 if (waited) { 2810 double scan_wait_end = os::elapsedTime(); 2811 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2812 } 2813 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2814 } 2815 2816 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2817 private: 2818 G1HRPrinter* _hr_printer; 2819 public: 2820 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2821 2822 virtual bool do_heap_region(HeapRegion* r) { 2823 _hr_printer->cset(r); 2824 return false; 2825 } 2826 }; 2827 2828 void G1CollectedHeap::start_new_collection_set() { 2829 double start = os::elapsedTime(); 2830 2831 collection_set()->start_incremental_building(); 2832 2833 clear_region_attr(); 2834 2835 guarantee(_eden.length() == 0, "eden should have been cleared"); 2836 policy()->transfer_survivors_to_cset(survivor()); 2837 2838 // We redo the verification but now wrt to the new CSet which 2839 // has just got initialized after the previous CSet was freed. 2840 _cm->verify_no_collection_set_oops(); 2841 2842 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2843 } 2844 2845 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2846 2847 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2848 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2849 collection_set()->optional_region_length()); 2850 2851 _cm->verify_no_collection_set_oops(); 2852 2853 if (_hr_printer.is_active()) { 2854 G1PrintCollectionSetClosure cl(&_hr_printer); 2855 _collection_set.iterate(&cl); 2856 _collection_set.iterate_optional(&cl); 2857 } 2858 } 2859 2860 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2861 if (collector_state()->in_concurrent_start_gc()) { 2862 return G1HeapVerifier::G1VerifyConcurrentStart; 2863 } else if (collector_state()->in_young_only_phase()) { 2864 return G1HeapVerifier::G1VerifyYoungNormal; 2865 } else { 2866 return G1HeapVerifier::G1VerifyMixed; 2867 } 2868 } 2869 2870 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2871 if (VerifyRememberedSets) { 2872 log_info(gc, verify)("[Verifying RemSets before GC]"); 2873 VerifyRegionRemSetClosure v_cl; 2874 heap_region_iterate(&v_cl); 2875 } 2876 _verifier->verify_before_gc(type); 2877 _verifier->check_bitmaps("GC Start"); 2878 verify_numa_regions("GC Start"); 2879 } 2880 2881 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2882 if (VerifyRememberedSets) { 2883 log_info(gc, verify)("[Verifying RemSets after GC]"); 2884 VerifyRegionRemSetClosure v_cl; 2885 heap_region_iterate(&v_cl); 2886 } 2887 _verifier->verify_after_gc(type); 2888 _verifier->check_bitmaps("GC End"); 2889 verify_numa_regions("GC End"); 2890 } 2891 2892 void G1CollectedHeap::expand_heap_after_young_collection(){ 2893 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount(); 2894 if (expand_bytes > 0) { 2895 // No need for an ergo logging here, 2896 // expansion_amount() does this when it returns a value > 0. 2897 double expand_ms; 2898 if (!expand(expand_bytes, _workers, &expand_ms)) { 2899 // We failed to expand the heap. Cannot do anything about it. 2900 } 2901 phase_times()->record_expand_heap_time(expand_ms); 2902 } 2903 } 2904 2905 const char* G1CollectedHeap::young_gc_name() const { 2906 if (collector_state()->in_concurrent_start_gc()) { 2907 return "Pause Young (Concurrent Start)"; 2908 } else if (collector_state()->in_young_only_phase()) { 2909 if (collector_state()->in_young_gc_before_mixed()) { 2910 return "Pause Young (Prepare Mixed)"; 2911 } else { 2912 return "Pause Young (Normal)"; 2913 } 2914 } else { 2915 return "Pause Young (Mixed)"; 2916 } 2917 } 2918 2919 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2920 assert_at_safepoint_on_vm_thread(); 2921 guarantee(!is_gc_active(), "collection is not reentrant"); 2922 2923 if (GCLocker::check_active_before_gc()) { 2924 return false; 2925 } 2926 2927 do_collection_pause_at_safepoint_helper(target_pause_time_ms); 2928 if (should_upgrade_to_full_gc(gc_cause())) { 2929 log_info(gc, ergo)("Attempting maximally compacting collection"); 2930 bool result = do_full_collection(false /* explicit gc */, 2931 true /* clear_all_soft_refs */); 2932 // do_full_collection only fails if blocked by GC locker, but 2933 // we've already checked for that above. 2934 assert(result, "invariant"); 2935 } 2936 return true; 2937 } 2938 2939 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) { 2940 GCIdMark gc_id_mark; 2941 2942 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2943 ResourceMark rm; 2944 2945 policy()->note_gc_start(); 2946 2947 _gc_timer_stw->register_gc_start(); 2948 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2949 2950 wait_for_root_region_scanning(); 2951 2952 print_heap_before_gc(); 2953 print_heap_regions(); 2954 trace_heap_before_gc(_gc_tracer_stw); 2955 2956 _verifier->verify_region_sets_optional(); 2957 _verifier->verify_dirty_young_regions(); 2958 2959 // We should not be doing concurrent start unless the concurrent mark thread is running 2960 if (!_cm_thread->should_terminate()) { 2961 // This call will decide whether this pause is a concurrent start 2962 // pause. If it is, in_concurrent_start_gc() will return true 2963 // for the duration of this pause. 2964 policy()->decide_on_conc_mark_initiation(); 2965 } 2966 2967 // We do not allow concurrent start to be piggy-backed on a mixed GC. 2968 assert(!collector_state()->in_concurrent_start_gc() || 2969 collector_state()->in_young_only_phase(), "sanity"); 2970 // We also do not allow mixed GCs during marking. 2971 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2972 2973 // Record whether this pause is a concurrent start. When the current 2974 // thread has completed its logging output and it's safe to signal 2975 // the CM thread, the flag's value in the policy has been reset. 2976 bool should_start_conc_mark = collector_state()->in_concurrent_start_gc(); 2977 if (should_start_conc_mark) { 2978 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2979 } 2980 2981 // Inner scope for scope based logging, timers, and stats collection 2982 { 2983 G1EvacuationInfo evacuation_info; 2984 2985 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2986 2987 GCTraceCPUTime tcpu; 2988 2989 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 2990 2991 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2992 workers()->active_workers(), 2993 Threads::number_of_non_daemon_threads()); 2994 active_workers = workers()->update_active_workers(active_workers); 2995 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2996 2997 G1MonitoringScope ms(g1mm(), 2998 false /* full_gc */, 2999 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3000 3001 G1HeapTransition heap_transition(this); 3002 3003 { 3004 IsGCActiveMark x; 3005 3006 gc_prologue(false); 3007 3008 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3009 verify_before_young_collection(verify_type); 3010 3011 { 3012 // The elapsed time induced by the start time below deliberately elides 3013 // the possible verification above. 3014 double sample_start_time_sec = os::elapsedTime(); 3015 3016 // Please see comment in g1CollectedHeap.hpp and 3017 // G1CollectedHeap::ref_processing_init() to see how 3018 // reference processing currently works in G1. 3019 _ref_processor_stw->enable_discovery(); 3020 3021 // We want to temporarily turn off discovery by the 3022 // CM ref processor, if necessary, and turn it back on 3023 // on again later if we do. Using a scoped 3024 // NoRefDiscovery object will do this. 3025 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3026 3027 policy()->record_collection_pause_start(sample_start_time_sec); 3028 3029 // Forget the current allocation region (we might even choose it to be part 3030 // of the collection set!). 3031 _allocator->release_mutator_alloc_regions(); 3032 3033 calculate_collection_set(evacuation_info, target_pause_time_ms); 3034 3035 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3036 G1ParScanThreadStateSet per_thread_states(this, 3037 &rdcqs, 3038 workers()->active_workers(), 3039 collection_set()->young_region_length(), 3040 collection_set()->optional_region_length()); 3041 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3042 3043 // Actually do the work... 3044 evacuate_initial_collection_set(&per_thread_states); 3045 3046 if (_collection_set.optional_region_length() != 0) { 3047 evacuate_optional_collection_set(&per_thread_states); 3048 } 3049 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3050 3051 start_new_collection_set(); 3052 3053 _survivor_evac_stats.adjust_desired_plab_sz(); 3054 _old_evac_stats.adjust_desired_plab_sz(); 3055 3056 if (should_start_conc_mark) { 3057 // We have to do this before we notify the CM threads that 3058 // they can start working to make sure that all the 3059 // appropriate initialization is done on the CM object. 3060 concurrent_mark()->post_concurrent_start(); 3061 // Note that we don't actually trigger the CM thread at 3062 // this point. We do that later when we're sure that 3063 // the current thread has completed its logging output. 3064 } 3065 3066 allocate_dummy_regions(); 3067 3068 _allocator->init_mutator_alloc_regions(); 3069 3070 expand_heap_after_young_collection(); 3071 3072 double sample_end_time_sec = os::elapsedTime(); 3073 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3074 policy()->record_collection_pause_end(pause_time_ms); 3075 } 3076 3077 verify_after_young_collection(verify_type); 3078 3079 gc_epilogue(false); 3080 } 3081 3082 // Print the remainder of the GC log output. 3083 if (evacuation_failed()) { 3084 log_info(gc)("To-space exhausted"); 3085 } 3086 3087 policy()->print_phases(); 3088 heap_transition.print(); 3089 3090 _hrm->verify_optional(); 3091 _verifier->verify_region_sets_optional(); 3092 3093 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3094 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3095 3096 print_heap_after_gc(); 3097 print_heap_regions(); 3098 trace_heap_after_gc(_gc_tracer_stw); 3099 3100 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3101 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3102 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3103 // before any GC notifications are raised. 3104 g1mm()->update_sizes(); 3105 3106 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3107 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3108 _gc_timer_stw->register_gc_end(); 3109 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3110 } 3111 // It should now be safe to tell the concurrent mark thread to start 3112 // without its logging output interfering with the logging output 3113 // that came from the pause. 3114 3115 if (should_start_conc_mark) { 3116 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3117 // thread(s) could be running concurrently with us. Make sure that anything 3118 // after this point does not assume that we are the only GC thread running. 3119 // Note: of course, the actual marking work will not start until the safepoint 3120 // itself is released in SuspendibleThreadSet::desynchronize(). 3121 do_concurrent_mark(); 3122 ConcurrentGCBreakpoints::notify_idle_to_active(); 3123 } 3124 } 3125 3126 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3127 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3128 workers()->run_task(&rsfp_task); 3129 } 3130 3131 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3132 double remove_self_forwards_start = os::elapsedTime(); 3133 3134 remove_self_forwarding_pointers(rdcqs); 3135 _preserved_marks_set.restore(workers()); 3136 3137 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3138 } 3139 3140 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3141 if (!_evacuation_failed) { 3142 _evacuation_failed = true; 3143 } 3144 3145 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3146 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3147 } 3148 3149 bool G1ParEvacuateFollowersClosure::offer_termination() { 3150 EventGCPhaseParallel event; 3151 G1ParScanThreadState* const pss = par_scan_state(); 3152 start_term_time(); 3153 const bool res = terminator()->offer_termination(); 3154 end_term_time(); 3155 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3156 return res; 3157 } 3158 3159 void G1ParEvacuateFollowersClosure::do_void() { 3160 EventGCPhaseParallel event; 3161 G1ParScanThreadState* const pss = par_scan_state(); 3162 pss->trim_queue(); 3163 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3164 do { 3165 EventGCPhaseParallel event; 3166 pss->steal_and_trim_queue(queues()); 3167 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3168 } while (!offer_termination()); 3169 } 3170 3171 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3172 bool class_unloading_occurred) { 3173 uint num_workers = workers()->active_workers(); 3174 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3175 workers()->run_task(&unlink_task); 3176 } 3177 3178 // Clean string dedup data structures. 3179 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3180 // record the durations of the phases. Hence the almost-copy. 3181 class G1StringDedupCleaningTask : public AbstractGangTask { 3182 BoolObjectClosure* _is_alive; 3183 OopClosure* _keep_alive; 3184 G1GCPhaseTimes* _phase_times; 3185 3186 public: 3187 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3188 OopClosure* keep_alive, 3189 G1GCPhaseTimes* phase_times) : 3190 AbstractGangTask("Partial Cleaning Task"), 3191 _is_alive(is_alive), 3192 _keep_alive(keep_alive), 3193 _phase_times(phase_times) 3194 { 3195 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3196 StringDedup::gc_prologue(true); 3197 } 3198 3199 ~G1StringDedupCleaningTask() { 3200 StringDedup::gc_epilogue(); 3201 } 3202 3203 void work(uint worker_id) { 3204 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3205 { 3206 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3207 StringDedupQueue::unlink_or_oops_do(&cl); 3208 } 3209 { 3210 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3211 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3212 } 3213 } 3214 }; 3215 3216 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3217 OopClosure* keep_alive, 3218 G1GCPhaseTimes* phase_times) { 3219 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3220 workers()->run_task(&cl); 3221 } 3222 3223 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3224 private: 3225 G1RedirtyCardsQueueSet* _qset; 3226 G1CollectedHeap* _g1h; 3227 BufferNode* volatile _nodes; 3228 3229 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3230 size_t buffer_size = _qset->buffer_size(); 3231 BufferNode* next = Atomic::load(&_nodes); 3232 while (next != NULL) { 3233 BufferNode* node = next; 3234 next = Atomic::cmpxchg(&_nodes, node, node->next()); 3235 if (next == node) { 3236 cl->apply_to_buffer(node, buffer_size, worker_id); 3237 next = node->next(); 3238 } 3239 } 3240 } 3241 3242 public: 3243 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3244 AbstractGangTask("Redirty Cards"), 3245 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3246 3247 virtual void work(uint worker_id) { 3248 G1GCPhaseTimes* p = _g1h->phase_times(); 3249 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3250 3251 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3252 par_apply(&cl, worker_id); 3253 3254 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3255 } 3256 }; 3257 3258 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3259 double redirty_logged_cards_start = os::elapsedTime(); 3260 3261 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3262 workers()->run_task(&redirty_task); 3263 3264 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3265 dcq.merge_bufferlists(rdcqs); 3266 3267 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3268 } 3269 3270 // Weak Reference Processing support 3271 3272 bool G1STWIsAliveClosure::do_object_b(oop p) { 3273 // An object is reachable if it is outside the collection set, 3274 // or is inside and copied. 3275 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3276 } 3277 3278 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3279 assert(obj != NULL, "must not be NULL"); 3280 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3281 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3282 // may falsely indicate that this is not the case here: however the collection set only 3283 // contains old regions when concurrent mark is not running. 3284 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3285 } 3286 3287 // Non Copying Keep Alive closure 3288 class G1KeepAliveClosure: public OopClosure { 3289 G1CollectedHeap*_g1h; 3290 public: 3291 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3292 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3293 void do_oop(oop* p) { 3294 oop obj = *p; 3295 assert(obj != NULL, "the caller should have filtered out NULL values"); 3296 3297 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3298 if (!region_attr.is_in_cset_or_humongous()) { 3299 return; 3300 } 3301 if (region_attr.is_in_cset()) { 3302 assert( obj->is_forwarded(), "invariant" ); 3303 *p = obj->forwardee(); 3304 } else { 3305 assert(!obj->is_forwarded(), "invariant" ); 3306 assert(region_attr.is_humongous(), 3307 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3308 _g1h->set_humongous_is_live(obj); 3309 } 3310 } 3311 }; 3312 3313 // Copying Keep Alive closure - can be called from both 3314 // serial and parallel code as long as different worker 3315 // threads utilize different G1ParScanThreadState instances 3316 // and different queues. 3317 3318 class G1CopyingKeepAliveClosure: public OopClosure { 3319 G1CollectedHeap* _g1h; 3320 G1ParScanThreadState* _par_scan_state; 3321 3322 public: 3323 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3324 G1ParScanThreadState* pss): 3325 _g1h(g1h), 3326 _par_scan_state(pss) 3327 {} 3328 3329 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3330 virtual void do_oop( oop* p) { do_oop_work(p); } 3331 3332 template <class T> void do_oop_work(T* p) { 3333 oop obj = RawAccess<>::oop_load(p); 3334 3335 if (_g1h->is_in_cset_or_humongous(obj)) { 3336 // If the referent object has been forwarded (either copied 3337 // to a new location or to itself in the event of an 3338 // evacuation failure) then we need to update the reference 3339 // field and, if both reference and referent are in the G1 3340 // heap, update the RSet for the referent. 3341 // 3342 // If the referent has not been forwarded then we have to keep 3343 // it alive by policy. Therefore we have copy the referent. 3344 // 3345 // When the queue is drained (after each phase of reference processing) 3346 // the object and it's followers will be copied, the reference field set 3347 // to point to the new location, and the RSet updated. 3348 _par_scan_state->push_on_queue(ScannerTask(p)); 3349 } 3350 } 3351 }; 3352 3353 // Serial drain queue closure. Called as the 'complete_gc' 3354 // closure for each discovered list in some of the 3355 // reference processing phases. 3356 3357 class G1STWDrainQueueClosure: public VoidClosure { 3358 protected: 3359 G1CollectedHeap* _g1h; 3360 G1ParScanThreadState* _par_scan_state; 3361 3362 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3363 3364 public: 3365 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3366 _g1h(g1h), 3367 _par_scan_state(pss) 3368 { } 3369 3370 void do_void() { 3371 G1ParScanThreadState* const pss = par_scan_state(); 3372 pss->trim_queue(); 3373 } 3374 }; 3375 3376 // Parallel Reference Processing closures 3377 3378 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3379 // processing during G1 evacuation pauses. 3380 3381 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3382 private: 3383 G1CollectedHeap* _g1h; 3384 G1ParScanThreadStateSet* _pss; 3385 G1ScannerTasksQueueSet* _queues; 3386 WorkGang* _workers; 3387 3388 public: 3389 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3390 G1ParScanThreadStateSet* per_thread_states, 3391 WorkGang* workers, 3392 G1ScannerTasksQueueSet *task_queues) : 3393 _g1h(g1h), 3394 _pss(per_thread_states), 3395 _queues(task_queues), 3396 _workers(workers) 3397 { 3398 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3399 } 3400 3401 // Executes the given task using concurrent marking worker threads. 3402 virtual void execute(ProcessTask& task, uint ergo_workers); 3403 }; 3404 3405 // Gang task for possibly parallel reference processing 3406 3407 class G1STWRefProcTaskProxy: public AbstractGangTask { 3408 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3409 ProcessTask& _proc_task; 3410 G1CollectedHeap* _g1h; 3411 G1ParScanThreadStateSet* _pss; 3412 G1ScannerTasksQueueSet* _task_queues; 3413 TaskTerminator* _terminator; 3414 3415 public: 3416 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3417 G1CollectedHeap* g1h, 3418 G1ParScanThreadStateSet* per_thread_states, 3419 G1ScannerTasksQueueSet *task_queues, 3420 TaskTerminator* terminator) : 3421 AbstractGangTask("Process reference objects in parallel"), 3422 _proc_task(proc_task), 3423 _g1h(g1h), 3424 _pss(per_thread_states), 3425 _task_queues(task_queues), 3426 _terminator(terminator) 3427 {} 3428 3429 virtual void work(uint worker_id) { 3430 // The reference processing task executed by a single worker. 3431 ResourceMark rm; 3432 3433 G1STWIsAliveClosure is_alive(_g1h); 3434 3435 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3436 pss->set_ref_discoverer(NULL); 3437 3438 // Keep alive closure. 3439 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3440 3441 // Complete GC closure 3442 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3443 3444 // Call the reference processing task's work routine. 3445 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3446 3447 // Note we cannot assert that the refs array is empty here as not all 3448 // of the processing tasks (specifically phase2 - pp2_work) execute 3449 // the complete_gc closure (which ordinarily would drain the queue) so 3450 // the queue may not be empty. 3451 } 3452 }; 3453 3454 // Driver routine for parallel reference processing. 3455 // Creates an instance of the ref processing gang 3456 // task and has the worker threads execute it. 3457 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3458 assert(_workers != NULL, "Need parallel worker threads."); 3459 3460 assert(_workers->active_workers() >= ergo_workers, 3461 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3462 ergo_workers, _workers->active_workers()); 3463 TaskTerminator terminator(ergo_workers, _queues); 3464 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3465 3466 _workers->run_task(&proc_task_proxy, ergo_workers); 3467 } 3468 3469 // End of weak reference support closures 3470 3471 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3472 double ref_proc_start = os::elapsedTime(); 3473 3474 ReferenceProcessor* rp = _ref_processor_stw; 3475 assert(rp->discovery_enabled(), "should have been enabled"); 3476 3477 // Closure to test whether a referent is alive. 3478 G1STWIsAliveClosure is_alive(this); 3479 3480 // Even when parallel reference processing is enabled, the processing 3481 // of JNI refs is serial and performed serially by the current thread 3482 // rather than by a worker. The following PSS will be used for processing 3483 // JNI refs. 3484 3485 // Use only a single queue for this PSS. 3486 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3487 pss->set_ref_discoverer(NULL); 3488 assert(pss->queue_is_empty(), "pre-condition"); 3489 3490 // Keep alive closure. 3491 G1CopyingKeepAliveClosure keep_alive(this, pss); 3492 3493 // Serial Complete GC closure 3494 G1STWDrainQueueClosure drain_queue(this, pss); 3495 3496 // Setup the soft refs policy... 3497 rp->setup_policy(false); 3498 3499 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3500 3501 ReferenceProcessorStats stats; 3502 if (!rp->processing_is_mt()) { 3503 // Serial reference processing... 3504 stats = rp->process_discovered_references(&is_alive, 3505 &keep_alive, 3506 &drain_queue, 3507 NULL, 3508 pt); 3509 } else { 3510 uint no_of_gc_workers = workers()->active_workers(); 3511 3512 // Parallel reference processing 3513 assert(no_of_gc_workers <= rp->max_num_queues(), 3514 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3515 no_of_gc_workers, rp->max_num_queues()); 3516 3517 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3518 stats = rp->process_discovered_references(&is_alive, 3519 &keep_alive, 3520 &drain_queue, 3521 &par_task_executor, 3522 pt); 3523 } 3524 3525 _gc_tracer_stw->report_gc_reference_stats(stats); 3526 3527 // We have completed copying any necessary live referent objects. 3528 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3529 3530 make_pending_list_reachable(); 3531 3532 assert(!rp->discovery_enabled(), "Postcondition"); 3533 rp->verify_no_references_recorded(); 3534 3535 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3536 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3537 } 3538 3539 void G1CollectedHeap::make_pending_list_reachable() { 3540 if (collector_state()->in_concurrent_start_gc()) { 3541 oop pll_head = Universe::reference_pending_list(); 3542 if (pll_head != NULL) { 3543 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3544 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3545 } 3546 } 3547 } 3548 3549 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3550 Ticks start = Ticks::now(); 3551 per_thread_states->flush(); 3552 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds()); 3553 } 3554 3555 class G1PrepareEvacuationTask : public AbstractGangTask { 3556 class G1PrepareRegionsClosure : public HeapRegionClosure { 3557 G1CollectedHeap* _g1h; 3558 G1PrepareEvacuationTask* _parent_task; 3559 size_t _worker_humongous_total; 3560 size_t _worker_humongous_candidates; 3561 3562 bool humongous_region_is_candidate(HeapRegion* region) const { 3563 assert(region->is_starts_humongous(), "Must start a humongous object"); 3564 3565 oop obj = oop(region->bottom()); 3566 3567 // Dead objects cannot be eager reclaim candidates. Due to class 3568 // unloading it is unsafe to query their classes so we return early. 3569 if (_g1h->is_obj_dead(obj, region)) { 3570 return false; 3571 } 3572 3573 // If we do not have a complete remembered set for the region, then we can 3574 // not be sure that we have all references to it. 3575 if (!region->rem_set()->is_complete()) { 3576 return false; 3577 } 3578 // Candidate selection must satisfy the following constraints 3579 // while concurrent marking is in progress: 3580 // 3581 // * In order to maintain SATB invariants, an object must not be 3582 // reclaimed if it was allocated before the start of marking and 3583 // has not had its references scanned. Such an object must have 3584 // its references (including type metadata) scanned to ensure no 3585 // live objects are missed by the marking process. Objects 3586 // allocated after the start of concurrent marking don't need to 3587 // be scanned. 3588 // 3589 // * An object must not be reclaimed if it is on the concurrent 3590 // mark stack. Objects allocated after the start of concurrent 3591 // marking are never pushed on the mark stack. 3592 // 3593 // Nominating only objects allocated after the start of concurrent 3594 // marking is sufficient to meet both constraints. This may miss 3595 // some objects that satisfy the constraints, but the marking data 3596 // structures don't support efficiently performing the needed 3597 // additional tests or scrubbing of the mark stack. 3598 // 3599 // However, we presently only nominate is_typeArray() objects. 3600 // A humongous object containing references induces remembered 3601 // set entries on other regions. In order to reclaim such an 3602 // object, those remembered sets would need to be cleaned up. 3603 // 3604 // We also treat is_typeArray() objects specially, allowing them 3605 // to be reclaimed even if allocated before the start of 3606 // concurrent mark. For this we rely on mark stack insertion to 3607 // exclude is_typeArray() objects, preventing reclaiming an object 3608 // that is in the mark stack. We also rely on the metadata for 3609 // such objects to be built-in and so ensured to be kept live. 3610 // Frequent allocation and drop of large binary blobs is an 3611 // important use case for eager reclaim, and this special handling 3612 // may reduce needed headroom. 3613 3614 return obj->is_typeArray() && 3615 _g1h->is_potential_eager_reclaim_candidate(region); 3616 } 3617 3618 public: 3619 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) : 3620 _g1h(g1h), 3621 _parent_task(parent_task), 3622 _worker_humongous_total(0), 3623 _worker_humongous_candidates(0) { } 3624 3625 ~G1PrepareRegionsClosure() { 3626 _parent_task->add_humongous_candidates(_worker_humongous_candidates); 3627 _parent_task->add_humongous_total(_worker_humongous_total); 3628 } 3629 3630 virtual bool do_heap_region(HeapRegion* hr) { 3631 // First prepare the region for scanning 3632 _g1h->rem_set()->prepare_region_for_scan(hr); 3633 3634 // Now check if region is a humongous candidate 3635 if (!hr->is_starts_humongous()) { 3636 _g1h->register_region_with_region_attr(hr); 3637 return false; 3638 } 3639 3640 uint index = hr->hrm_index(); 3641 if (humongous_region_is_candidate(hr)) { 3642 _g1h->set_humongous_reclaim_candidate(index, true); 3643 _g1h->register_humongous_region_with_region_attr(index); 3644 _worker_humongous_candidates++; 3645 // We will later handle the remembered sets of these regions. 3646 } else { 3647 _g1h->set_humongous_reclaim_candidate(index, false); 3648 _g1h->register_region_with_region_attr(hr); 3649 } 3650 _worker_humongous_total++; 3651 3652 return false; 3653 } 3654 }; 3655 3656 G1CollectedHeap* _g1h; 3657 HeapRegionClaimer _claimer; 3658 volatile size_t _humongous_total; 3659 volatile size_t _humongous_candidates; 3660 public: 3661 G1PrepareEvacuationTask(G1CollectedHeap* g1h) : 3662 AbstractGangTask("Prepare Evacuation"), 3663 _g1h(g1h), 3664 _claimer(_g1h->workers()->active_workers()), 3665 _humongous_total(0), 3666 _humongous_candidates(0) { } 3667 3668 ~G1PrepareEvacuationTask() { 3669 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0); 3670 } 3671 3672 void work(uint worker_id) { 3673 G1PrepareRegionsClosure cl(_g1h, this); 3674 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id); 3675 } 3676 3677 void add_humongous_candidates(size_t candidates) { 3678 Atomic::add(&_humongous_candidates, candidates); 3679 } 3680 3681 void add_humongous_total(size_t total) { 3682 Atomic::add(&_humongous_total, total); 3683 } 3684 3685 size_t humongous_candidates() { 3686 return _humongous_candidates; 3687 } 3688 3689 size_t humongous_total() { 3690 return _humongous_total; 3691 } 3692 }; 3693 3694 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3695 _bytes_used_during_gc = 0; 3696 3697 _expand_heap_after_alloc_failure = true; 3698 _evacuation_failed = false; 3699 3700 // Disable the hot card cache. 3701 _hot_card_cache->reset_hot_cache_claimed_index(); 3702 _hot_card_cache->set_use_cache(false); 3703 3704 // Initialize the GC alloc regions. 3705 _allocator->init_gc_alloc_regions(evacuation_info); 3706 3707 { 3708 Ticks start = Ticks::now(); 3709 rem_set()->prepare_for_scan_heap_roots(); 3710 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3711 } 3712 3713 { 3714 G1PrepareEvacuationTask g1_prep_task(this); 3715 Tickspan task_time = run_task_timed(&g1_prep_task); 3716 3717 phase_times()->record_register_regions(task_time.seconds() * 1000.0, 3718 g1_prep_task.humongous_total(), 3719 g1_prep_task.humongous_candidates()); 3720 } 3721 3722 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3723 _preserved_marks_set.assert_empty(); 3724 3725 #if COMPILER2_OR_JVMCI 3726 DerivedPointerTable::clear(); 3727 #endif 3728 3729 // Concurrent start needs claim bits to keep track of the marked-through CLDs. 3730 if (collector_state()->in_concurrent_start_gc()) { 3731 concurrent_mark()->pre_concurrent_start(); 3732 3733 double start_clear_claimed_marks = os::elapsedTime(); 3734 3735 ClassLoaderDataGraph::clear_claimed_marks(); 3736 3737 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3738 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3739 } 3740 3741 // Should G1EvacuationFailureALot be in effect for this GC? 3742 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3743 } 3744 3745 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3746 protected: 3747 G1CollectedHeap* _g1h; 3748 G1ParScanThreadStateSet* _per_thread_states; 3749 G1ScannerTasksQueueSet* _task_queues; 3750 TaskTerminator _terminator; 3751 uint _num_workers; 3752 3753 void evacuate_live_objects(G1ParScanThreadState* pss, 3754 uint worker_id, 3755 G1GCPhaseTimes::GCParPhases objcopy_phase, 3756 G1GCPhaseTimes::GCParPhases termination_phase) { 3757 G1GCPhaseTimes* p = _g1h->phase_times(); 3758 3759 Ticks start = Ticks::now(); 3760 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase); 3761 cl.do_void(); 3762 3763 assert(pss->queue_is_empty(), "should be empty"); 3764 3765 Tickspan evac_time = (Ticks::now() - start); 3766 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3767 3768 if (termination_phase == G1GCPhaseTimes::Termination) { 3769 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3770 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3771 } else { 3772 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3773 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3774 } 3775 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3776 } 3777 3778 virtual void start_work(uint worker_id) { } 3779 3780 virtual void end_work(uint worker_id) { } 3781 3782 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3783 3784 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3785 3786 public: 3787 G1EvacuateRegionsBaseTask(const char* name, 3788 G1ParScanThreadStateSet* per_thread_states, 3789 G1ScannerTasksQueueSet* task_queues, 3790 uint num_workers) : 3791 AbstractGangTask(name), 3792 _g1h(G1CollectedHeap::heap()), 3793 _per_thread_states(per_thread_states), 3794 _task_queues(task_queues), 3795 _terminator(num_workers, _task_queues), 3796 _num_workers(num_workers) 3797 { } 3798 3799 void work(uint worker_id) { 3800 start_work(worker_id); 3801 3802 { 3803 ResourceMark rm; 3804 3805 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3806 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3807 3808 scan_roots(pss, worker_id); 3809 evacuate_live_objects(pss, worker_id); 3810 } 3811 3812 end_work(worker_id); 3813 } 3814 }; 3815 3816 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3817 G1RootProcessor* _root_processor; 3818 3819 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3820 _root_processor->evacuate_roots(pss, worker_id); 3821 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3822 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3823 } 3824 3825 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3826 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3827 } 3828 3829 void start_work(uint worker_id) { 3830 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3831 } 3832 3833 void end_work(uint worker_id) { 3834 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3835 } 3836 3837 public: 3838 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3839 G1ParScanThreadStateSet* per_thread_states, 3840 G1ScannerTasksQueueSet* task_queues, 3841 G1RootProcessor* root_processor, 3842 uint num_workers) : 3843 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3844 _root_processor(root_processor) 3845 { } 3846 }; 3847 3848 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3849 G1GCPhaseTimes* p = phase_times(); 3850 3851 { 3852 Ticks start = Ticks::now(); 3853 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3854 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3855 } 3856 3857 Tickspan task_time; 3858 const uint num_workers = workers()->active_workers(); 3859 3860 Ticks start_processing = Ticks::now(); 3861 { 3862 G1RootProcessor root_processor(this, num_workers); 3863 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3864 task_time = run_task_timed(&g1_par_task); 3865 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3866 // To extract its code root fixup time we measure total time of this scope and 3867 // subtract from the time the WorkGang task took. 3868 } 3869 Tickspan total_processing = Ticks::now() - start_processing; 3870 3871 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3872 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3873 } 3874 3875 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3876 3877 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3878 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3879 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3880 } 3881 3882 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3883 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3884 } 3885 3886 public: 3887 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3888 G1ScannerTasksQueueSet* queues, 3889 uint num_workers) : 3890 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3891 } 3892 }; 3893 3894 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3895 class G1MarkScope : public MarkScope { }; 3896 3897 Tickspan task_time; 3898 3899 Ticks start_processing = Ticks::now(); 3900 { 3901 G1MarkScope code_mark_scope; 3902 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3903 task_time = run_task_timed(&task); 3904 // See comment in evacuate_collection_set() for the reason of the scope. 3905 } 3906 Tickspan total_processing = Ticks::now() - start_processing; 3907 3908 G1GCPhaseTimes* p = phase_times(); 3909 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3910 } 3911 3912 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3913 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3914 3915 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3916 3917 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3918 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3919 3920 if (time_left_ms < 0 || 3921 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3922 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3923 _collection_set.optional_region_length(), time_left_ms); 3924 break; 3925 } 3926 3927 { 3928 Ticks start = Ticks::now(); 3929 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3930 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3931 } 3932 3933 { 3934 Ticks start = Ticks::now(); 3935 evacuate_next_optional_regions(per_thread_states); 3936 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3937 } 3938 } 3939 3940 _collection_set.abandon_optional_collection_set(per_thread_states); 3941 } 3942 3943 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3944 G1RedirtyCardsQueueSet* rdcqs, 3945 G1ParScanThreadStateSet* per_thread_states) { 3946 G1GCPhaseTimes* p = phase_times(); 3947 3948 rem_set()->cleanup_after_scan_heap_roots(); 3949 3950 // Process any discovered reference objects - we have 3951 // to do this _before_ we retire the GC alloc regions 3952 // as we may have to copy some 'reachable' referent 3953 // objects (and their reachable sub-graphs) that were 3954 // not copied during the pause. 3955 process_discovered_references(per_thread_states); 3956 3957 G1STWIsAliveClosure is_alive(this); 3958 G1KeepAliveClosure keep_alive(this); 3959 3960 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times()); 3961 3962 if (G1StringDedup::is_enabled()) { 3963 double string_dedup_time_ms = os::elapsedTime(); 3964 3965 string_dedup_cleaning(&is_alive, &keep_alive, p); 3966 3967 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3968 p->record_string_deduplication_time(string_cleanup_time_ms); 3969 } 3970 3971 _allocator->release_gc_alloc_regions(evacuation_info); 3972 3973 if (evacuation_failed()) { 3974 restore_after_evac_failure(rdcqs); 3975 3976 // Reset the G1EvacuationFailureALot counters and flags 3977 NOT_PRODUCT(reset_evacuation_should_fail();) 3978 3979 double recalculate_used_start = os::elapsedTime(); 3980 set_used(recalculate_used()); 3981 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3982 3983 if (_archive_allocator != NULL) { 3984 _archive_allocator->clear_used(); 3985 } 3986 for (uint i = 0; i < ParallelGCThreads; i++) { 3987 if (_evacuation_failed_info_array[i].has_failed()) { 3988 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3989 } 3990 } 3991 } else { 3992 // The "used" of the the collection set have already been subtracted 3993 // when they were freed. Add in the bytes used. 3994 increase_used(_bytes_used_during_gc); 3995 } 3996 3997 _preserved_marks_set.assert_empty(); 3998 3999 merge_per_thread_state_info(per_thread_states); 4000 4001 // Reset and re-enable the hot card cache. 4002 // Note the counts for the cards in the regions in the 4003 // collection set are reset when the collection set is freed. 4004 _hot_card_cache->reset_hot_cache(); 4005 _hot_card_cache->set_use_cache(true); 4006 4007 purge_code_root_memory(); 4008 4009 redirty_logged_cards(rdcqs); 4010 4011 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4012 4013 eagerly_reclaim_humongous_regions(); 4014 4015 record_obj_copy_mem_stats(); 4016 4017 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4018 evacuation_info.set_bytes_used(_bytes_used_during_gc); 4019 4020 #if COMPILER2_OR_JVMCI 4021 double start = os::elapsedTime(); 4022 DerivedPointerTable::update_pointers(); 4023 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4024 #endif 4025 policy()->print_age_table(); 4026 } 4027 4028 void G1CollectedHeap::record_obj_copy_mem_stats() { 4029 policy()->old_gen_alloc_tracker()-> 4030 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4031 4032 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4033 create_g1_evac_summary(&_old_evac_stats)); 4034 } 4035 4036 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 4037 assert(!hr->is_free(), "the region should not be free"); 4038 assert(!hr->is_empty(), "the region should not be empty"); 4039 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4040 4041 if (G1VerifyBitmaps) { 4042 MemRegion mr(hr->bottom(), hr->end()); 4043 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4044 } 4045 4046 // Clear the card counts for this region. 4047 // Note: we only need to do this if the region is not young 4048 // (since we don't refine cards in young regions). 4049 if (!hr->is_young()) { 4050 _hot_card_cache->reset_card_counts(hr); 4051 } 4052 4053 // Reset region metadata to allow reuse. 4054 hr->hr_clear(true /* clear_space */); 4055 _policy->remset_tracker()->update_at_free(hr); 4056 4057 if (free_list != NULL) { 4058 free_list->add_ordered(hr); 4059 } 4060 } 4061 4062 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4063 FreeRegionList* free_list) { 4064 assert(hr->is_humongous(), "this is only for humongous regions"); 4065 assert(free_list != NULL, "pre-condition"); 4066 hr->clear_humongous(); 4067 free_region(hr, free_list); 4068 } 4069 4070 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4071 const uint humongous_regions_removed) { 4072 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4073 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4074 _old_set.bulk_remove(old_regions_removed); 4075 _humongous_set.bulk_remove(humongous_regions_removed); 4076 } 4077 4078 } 4079 4080 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4081 assert(list != NULL, "list can't be null"); 4082 if (!list->is_empty()) { 4083 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4084 _hrm->insert_list_into_free_list(list); 4085 } 4086 } 4087 4088 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4089 decrease_used(bytes); 4090 } 4091 4092 class G1FreeCollectionSetTask : public AbstractGangTask { 4093 // Helper class to keep statistics for the collection set freeing 4094 class FreeCSetStats { 4095 size_t _before_used_bytes; // Usage in regions successfully evacutate 4096 size_t _after_used_bytes; // Usage in regions failing evacuation 4097 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old 4098 size_t _failure_used_words; // Live size in failed regions 4099 size_t _failure_waste_words; // Wasted size in failed regions 4100 size_t _rs_length; // Remembered set size 4101 uint _regions_freed; // Number of regions freed 4102 public: 4103 FreeCSetStats() : 4104 _before_used_bytes(0), 4105 _after_used_bytes(0), 4106 _bytes_allocated_in_old_since_last_gc(0), 4107 _failure_used_words(0), 4108 _failure_waste_words(0), 4109 _rs_length(0), 4110 _regions_freed(0) { } 4111 4112 void merge_stats(FreeCSetStats* other) { 4113 assert(other != NULL, "invariant"); 4114 _before_used_bytes += other->_before_used_bytes; 4115 _after_used_bytes += other->_after_used_bytes; 4116 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc; 4117 _failure_used_words += other->_failure_used_words; 4118 _failure_waste_words += other->_failure_waste_words; 4119 _rs_length += other->_rs_length; 4120 _regions_freed += other->_regions_freed; 4121 } 4122 4123 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) { 4124 evacuation_info->set_regions_freed(_regions_freed); 4125 evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4126 4127 g1h->decrement_summary_bytes(_before_used_bytes); 4128 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4129 4130 G1Policy *policy = g1h->policy(); 4131 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4132 policy->record_rs_length(_rs_length); 4133 policy->cset_regions_freed(); 4134 } 4135 4136 void account_failed_region(HeapRegion* r) { 4137 size_t used_words = r->marked_bytes() / HeapWordSize; 4138 _failure_used_words += used_words; 4139 _failure_waste_words += HeapRegion::GrainWords - used_words; 4140 _after_used_bytes += r->used(); 4141 4142 // When moving a young gen region to old gen, we "allocate" that whole 4143 // region there. This is in addition to any already evacuated objects. 4144 // Notify the policy about that. Old gen regions do not cause an 4145 // additional allocation: both the objects still in the region and the 4146 // ones already moved are accounted for elsewhere. 4147 if (r->is_young()) { 4148 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4149 } 4150 } 4151 4152 void account_evacuated_region(HeapRegion* r) { 4153 _before_used_bytes += r->used(); 4154 _regions_freed += 1; 4155 } 4156 4157 void account_rs_length(HeapRegion* r) { 4158 _rs_length += r->rem_set()->occupied(); 4159 } 4160 }; 4161 4162 // Closure applied to all regions in the collection set. 4163 class FreeCSetClosure : public HeapRegionClosure { 4164 // Helper to send JFR events for regions. 4165 class JFREventForRegion { 4166 EventGCPhaseParallel _event; 4167 public: 4168 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() { 4169 _event.set_gcId(GCId::current()); 4170 _event.set_gcWorkerId(worker_id); 4171 if (region->is_young()) { 4172 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4173 } else { 4174 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4175 } 4176 } 4177 4178 ~JFREventForRegion() { 4179 _event.commit(); 4180 } 4181 }; 4182 4183 // Helper to do timing for region work. 4184 class TimerForRegion { 4185 Tickspan& _time; 4186 Ticks _start_time; 4187 public: 4188 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { } 4189 ~TimerForRegion() { 4190 _time += Ticks::now() - _start_time; 4191 } 4192 }; 4193 4194 // FreeCSetClosure members 4195 G1CollectedHeap* _g1h; 4196 const size_t* _surviving_young_words; 4197 uint _worker_id; 4198 Tickspan _young_time; 4199 Tickspan _non_young_time; 4200 FreeCSetStats* _stats; 4201 4202 void assert_in_cset(HeapRegion* r) { 4203 assert(r->young_index_in_cset() != 0 && 4204 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(), 4205 "Young index %u is wrong for region %u of type %s with %u young regions", 4206 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length()); 4207 } 4208 4209 void handle_evacuated_region(HeapRegion* r) { 4210 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4211 stats()->account_evacuated_region(r); 4212 4213 // Free the region and and its remembered set. 4214 _g1h->free_region(r, NULL); 4215 } 4216 4217 void handle_failed_region(HeapRegion* r) { 4218 // Do some allocation statistics accounting. Regions that failed evacuation 4219 // are always made old, so there is no need to update anything in the young 4220 // gen statistics, but we need to update old gen statistics. 4221 stats()->account_failed_region(r); 4222 4223 // Update the region state due to the failed evacuation. 4224 r->handle_evacuation_failure(); 4225 4226 // Add region to old set, need to hold lock. 4227 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4228 _g1h->old_set_add(r); 4229 } 4230 4231 Tickspan& timer_for_region(HeapRegion* r) { 4232 return r->is_young() ? _young_time : _non_young_time; 4233 } 4234 4235 FreeCSetStats* stats() { 4236 return _stats; 4237 } 4238 public: 4239 FreeCSetClosure(const size_t* surviving_young_words, 4240 uint worker_id, 4241 FreeCSetStats* stats) : 4242 HeapRegionClosure(), 4243 _g1h(G1CollectedHeap::heap()), 4244 _surviving_young_words(surviving_young_words), 4245 _worker_id(worker_id), 4246 _young_time(), 4247 _non_young_time(), 4248 _stats(stats) { } 4249 4250 virtual bool do_heap_region(HeapRegion* r) { 4251 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index()); 4252 JFREventForRegion event(r, _worker_id); 4253 TimerForRegion timer(timer_for_region(r)); 4254 4255 _g1h->clear_region_attr(r); 4256 stats()->account_rs_length(r); 4257 4258 if (r->is_young()) { 4259 assert_in_cset(r); 4260 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]); 4261 } 4262 4263 if (r->evacuation_failed()) { 4264 handle_failed_region(r); 4265 } else { 4266 handle_evacuated_region(r); 4267 } 4268 assert(!_g1h->is_on_master_free_list(r), "sanity"); 4269 4270 return false; 4271 } 4272 4273 void report_timing(Tickspan parallel_time) { 4274 G1GCPhaseTimes* pt = _g1h->phase_times(); 4275 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds()); 4276 if (_young_time.value() > 0) { 4277 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds()); 4278 } 4279 if (_non_young_time.value() > 0) { 4280 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds()); 4281 } 4282 } 4283 }; 4284 4285 // G1FreeCollectionSetTask members 4286 G1CollectedHeap* _g1h; 4287 G1EvacuationInfo* _evacuation_info; 4288 FreeCSetStats* _worker_stats; 4289 HeapRegionClaimer _claimer; 4290 const size_t* _surviving_young_words; 4291 uint _active_workers; 4292 4293 FreeCSetStats* worker_stats(uint worker) { 4294 return &_worker_stats[worker]; 4295 } 4296 4297 void report_statistics() { 4298 // Merge the accounting 4299 FreeCSetStats total_stats; 4300 for (uint worker = 0; worker < _active_workers; worker++) { 4301 total_stats.merge_stats(worker_stats(worker)); 4302 } 4303 total_stats.report(_g1h, _evacuation_info); 4304 } 4305 4306 public: 4307 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) : 4308 AbstractGangTask("G1 Free Collection Set"), 4309 _g1h(G1CollectedHeap::heap()), 4310 _evacuation_info(evacuation_info), 4311 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)), 4312 _claimer(active_workers), 4313 _surviving_young_words(surviving_young_words), 4314 _active_workers(active_workers) { 4315 for (uint worker = 0; worker < active_workers; worker++) { 4316 ::new (&_worker_stats[worker]) FreeCSetStats(); 4317 } 4318 } 4319 4320 ~G1FreeCollectionSetTask() { 4321 Ticks serial_time = Ticks::now(); 4322 report_statistics(); 4323 for (uint worker = 0; worker < _active_workers; worker++) { 4324 _worker_stats[worker].~FreeCSetStats(); 4325 } 4326 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats); 4327 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0); 4328 } 4329 4330 virtual void work(uint worker_id) { 4331 EventGCPhaseParallel event; 4332 Ticks start = Ticks::now(); 4333 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id)); 4334 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id); 4335 4336 // Report the total parallel time along with some more detailed metrics. 4337 cl.report_timing(Ticks::now() - start); 4338 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet)); 4339 } 4340 }; 4341 4342 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4343 _eden.clear(); 4344 4345 // The free collections set is split up in two tasks, the first 4346 // frees the collection set and records what regions are free, 4347 // and the second one rebuilds the free list. This proved to be 4348 // more efficient than adding a sorted list to another. 4349 4350 Ticks free_cset_start_time = Ticks::now(); 4351 { 4352 uint const num_cs_regions = _collection_set.region_length(); 4353 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers()); 4354 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers); 4355 4356 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)", 4357 cl.name(), num_workers, num_cs_regions, num_regions()); 4358 workers()->run_task(&cl, num_workers); 4359 } 4360 4361 Ticks free_cset_end_time = Ticks::now(); 4362 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0); 4363 4364 // Now rebuild the free region list. 4365 hrm()->rebuild_free_list(workers()); 4366 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0); 4367 4368 collection_set->clear(); 4369 } 4370 4371 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4372 private: 4373 FreeRegionList* _free_region_list; 4374 HeapRegionSet* _proxy_set; 4375 uint _humongous_objects_reclaimed; 4376 uint _humongous_regions_reclaimed; 4377 size_t _freed_bytes; 4378 public: 4379 4380 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4381 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4382 } 4383 4384 virtual bool do_heap_region(HeapRegion* r) { 4385 if (!r->is_starts_humongous()) { 4386 return false; 4387 } 4388 4389 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4390 4391 oop obj = (oop)r->bottom(); 4392 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4393 4394 // The following checks whether the humongous object is live are sufficient. 4395 // The main additional check (in addition to having a reference from the roots 4396 // or the young gen) is whether the humongous object has a remembered set entry. 4397 // 4398 // A humongous object cannot be live if there is no remembered set for it 4399 // because: 4400 // - there can be no references from within humongous starts regions referencing 4401 // the object because we never allocate other objects into them. 4402 // (I.e. there are no intra-region references that may be missed by the 4403 // remembered set) 4404 // - as soon there is a remembered set entry to the humongous starts region 4405 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4406 // until the end of a concurrent mark. 4407 // 4408 // It is not required to check whether the object has been found dead by marking 4409 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4410 // all objects allocated during that time are considered live. 4411 // SATB marking is even more conservative than the remembered set. 4412 // So if at this point in the collection there is no remembered set entry, 4413 // nobody has a reference to it. 4414 // At the start of collection we flush all refinement logs, and remembered sets 4415 // are completely up-to-date wrt to references to the humongous object. 4416 // 4417 // Other implementation considerations: 4418 // - never consider object arrays at this time because they would pose 4419 // considerable effort for cleaning up the the remembered sets. This is 4420 // required because stale remembered sets might reference locations that 4421 // are currently allocated into. 4422 uint region_idx = r->hrm_index(); 4423 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4424 !r->rem_set()->is_empty()) { 4425 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", 4426 region_idx, 4427 (size_t)obj->size() * HeapWordSize, 4428 p2i(r->bottom()), 4429 r->rem_set()->occupied(), 4430 r->rem_set()->strong_code_roots_list_length(), 4431 next_bitmap->is_marked(r->bottom()), 4432 g1h->is_humongous_reclaim_candidate(region_idx), 4433 obj->is_typeArray() 4434 ); 4435 return false; 4436 } 4437 4438 guarantee(obj->is_typeArray(), 4439 "Only eagerly reclaiming type arrays is supported, but the object " 4440 PTR_FORMAT " is not.", p2i(r->bottom())); 4441 4442 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", 4443 region_idx, 4444 (size_t)obj->size() * HeapWordSize, 4445 p2i(r->bottom()), 4446 r->rem_set()->occupied(), 4447 r->rem_set()->strong_code_roots_list_length(), 4448 next_bitmap->is_marked(r->bottom()), 4449 g1h->is_humongous_reclaim_candidate(region_idx), 4450 obj->is_typeArray() 4451 ); 4452 4453 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4454 cm->humongous_object_eagerly_reclaimed(r); 4455 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4456 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4457 region_idx, 4458 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4459 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4460 _humongous_objects_reclaimed++; 4461 do { 4462 HeapRegion* next = g1h->next_region_in_humongous(r); 4463 _freed_bytes += r->used(); 4464 r->set_containing_set(NULL); 4465 _humongous_regions_reclaimed++; 4466 g1h->free_humongous_region(r, _free_region_list); 4467 r = next; 4468 } while (r != NULL); 4469 4470 return false; 4471 } 4472 4473 uint humongous_objects_reclaimed() { 4474 return _humongous_objects_reclaimed; 4475 } 4476 4477 uint humongous_regions_reclaimed() { 4478 return _humongous_regions_reclaimed; 4479 } 4480 4481 size_t bytes_freed() const { 4482 return _freed_bytes; 4483 } 4484 }; 4485 4486 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4487 assert_at_safepoint_on_vm_thread(); 4488 4489 if (!G1EagerReclaimHumongousObjects || 4490 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4491 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4492 return; 4493 } 4494 4495 double start_time = os::elapsedTime(); 4496 4497 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4498 4499 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4500 heap_region_iterate(&cl); 4501 4502 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4503 4504 G1HRPrinter* hrp = hr_printer(); 4505 if (hrp->is_active()) { 4506 FreeRegionListIterator iter(&local_cleanup_list); 4507 while (iter.more_available()) { 4508 HeapRegion* hr = iter.get_next(); 4509 hrp->cleanup(hr); 4510 } 4511 } 4512 4513 prepend_to_freelist(&local_cleanup_list); 4514 decrement_summary_bytes(cl.bytes_freed()); 4515 4516 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4517 cl.humongous_objects_reclaimed()); 4518 } 4519 4520 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4521 public: 4522 virtual bool do_heap_region(HeapRegion* r) { 4523 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4524 G1CollectedHeap::heap()->clear_region_attr(r); 4525 r->clear_young_index_in_cset(); 4526 return false; 4527 } 4528 }; 4529 4530 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4531 G1AbandonCollectionSetClosure cl; 4532 collection_set_iterate_all(&cl); 4533 4534 collection_set->clear(); 4535 collection_set->stop_incremental_building(); 4536 } 4537 4538 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4539 return _allocator->is_retained_old_region(hr); 4540 } 4541 4542 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4543 _eden.add(hr); 4544 _policy->set_region_eden(hr); 4545 } 4546 4547 #ifdef ASSERT 4548 4549 class NoYoungRegionsClosure: public HeapRegionClosure { 4550 private: 4551 bool _success; 4552 public: 4553 NoYoungRegionsClosure() : _success(true) { } 4554 bool do_heap_region(HeapRegion* r) { 4555 if (r->is_young()) { 4556 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4557 p2i(r->bottom()), p2i(r->end())); 4558 _success = false; 4559 } 4560 return false; 4561 } 4562 bool success() { return _success; } 4563 }; 4564 4565 bool G1CollectedHeap::check_young_list_empty() { 4566 bool ret = (young_regions_count() == 0); 4567 4568 NoYoungRegionsClosure closure; 4569 heap_region_iterate(&closure); 4570 ret = ret && closure.success(); 4571 4572 return ret; 4573 } 4574 4575 #endif // ASSERT 4576 4577 class TearDownRegionSetsClosure : public HeapRegionClosure { 4578 HeapRegionSet *_old_set; 4579 4580 public: 4581 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4582 4583 bool do_heap_region(HeapRegion* r) { 4584 if (r->is_old()) { 4585 _old_set->remove(r); 4586 } else if(r->is_young()) { 4587 r->uninstall_surv_rate_group(); 4588 } else { 4589 // We ignore free regions, we'll empty the free list afterwards. 4590 // We ignore humongous and archive regions, we're not tearing down these 4591 // sets. 4592 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4593 "it cannot be another type"); 4594 } 4595 return false; 4596 } 4597 4598 ~TearDownRegionSetsClosure() { 4599 assert(_old_set->is_empty(), "post-condition"); 4600 } 4601 }; 4602 4603 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4604 assert_at_safepoint_on_vm_thread(); 4605 4606 if (!free_list_only) { 4607 TearDownRegionSetsClosure cl(&_old_set); 4608 heap_region_iterate(&cl); 4609 4610 // Note that emptying the _young_list is postponed and instead done as 4611 // the first step when rebuilding the regions sets again. The reason for 4612 // this is that during a full GC string deduplication needs to know if 4613 // a collected region was young or old when the full GC was initiated. 4614 } 4615 _hrm->remove_all_free_regions(); 4616 } 4617 4618 void G1CollectedHeap::increase_used(size_t bytes) { 4619 _summary_bytes_used += bytes; 4620 } 4621 4622 void G1CollectedHeap::decrease_used(size_t bytes) { 4623 assert(_summary_bytes_used >= bytes, 4624 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4625 _summary_bytes_used, bytes); 4626 _summary_bytes_used -= bytes; 4627 } 4628 4629 void G1CollectedHeap::set_used(size_t bytes) { 4630 _summary_bytes_used = bytes; 4631 } 4632 4633 class RebuildRegionSetsClosure : public HeapRegionClosure { 4634 private: 4635 bool _free_list_only; 4636 4637 HeapRegionSet* _old_set; 4638 HeapRegionManager* _hrm; 4639 4640 size_t _total_used; 4641 4642 public: 4643 RebuildRegionSetsClosure(bool free_list_only, 4644 HeapRegionSet* old_set, 4645 HeapRegionManager* hrm) : 4646 _free_list_only(free_list_only), 4647 _old_set(old_set), _hrm(hrm), _total_used(0) { 4648 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4649 if (!free_list_only) { 4650 assert(_old_set->is_empty(), "pre-condition"); 4651 } 4652 } 4653 4654 bool do_heap_region(HeapRegion* r) { 4655 if (r->is_empty()) { 4656 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4657 // Add free regions to the free list 4658 r->set_free(); 4659 _hrm->insert_into_free_list(r); 4660 } else if (!_free_list_only) { 4661 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4662 4663 if (r->is_archive() || r->is_humongous()) { 4664 // We ignore archive and humongous regions. We left these sets unchanged. 4665 } else { 4666 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4667 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4668 r->move_to_old(); 4669 _old_set->add(r); 4670 } 4671 _total_used += r->used(); 4672 } 4673 4674 return false; 4675 } 4676 4677 size_t total_used() { 4678 return _total_used; 4679 } 4680 }; 4681 4682 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4683 assert_at_safepoint_on_vm_thread(); 4684 4685 if (!free_list_only) { 4686 _eden.clear(); 4687 _survivor.clear(); 4688 } 4689 4690 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4691 heap_region_iterate(&cl); 4692 4693 if (!free_list_only) { 4694 set_used(cl.total_used()); 4695 if (_archive_allocator != NULL) { 4696 _archive_allocator->clear_used(); 4697 } 4698 } 4699 assert_used_and_recalculate_used_equal(this); 4700 } 4701 4702 // Methods for the mutator alloc region 4703 4704 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4705 bool force, 4706 uint node_index) { 4707 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4708 bool should_allocate = policy()->should_allocate_mutator_region(); 4709 if (force || should_allocate) { 4710 HeapRegion* new_alloc_region = new_region(word_size, 4711 HeapRegionType::Eden, 4712 false /* do_expand */, 4713 node_index); 4714 if (new_alloc_region != NULL) { 4715 set_region_short_lived_locked(new_alloc_region); 4716 _hr_printer.alloc(new_alloc_region, !should_allocate); 4717 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4718 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4719 return new_alloc_region; 4720 } 4721 } 4722 return NULL; 4723 } 4724 4725 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4726 size_t allocated_bytes) { 4727 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4728 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4729 4730 collection_set()->add_eden_region(alloc_region); 4731 increase_used(allocated_bytes); 4732 _eden.add_used_bytes(allocated_bytes); 4733 _hr_printer.retire(alloc_region); 4734 4735 // We update the eden sizes here, when the region is retired, 4736 // instead of when it's allocated, since this is the point that its 4737 // used space has been recorded in _summary_bytes_used. 4738 g1mm()->update_eden_size(); 4739 } 4740 4741 // Methods for the GC alloc regions 4742 4743 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4744 if (dest.is_old()) { 4745 return true; 4746 } else { 4747 return survivor_regions_count() < policy()->max_survivor_regions(); 4748 } 4749 } 4750 4751 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4752 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4753 4754 if (!has_more_regions(dest)) { 4755 return NULL; 4756 } 4757 4758 HeapRegionType type; 4759 if (dest.is_young()) { 4760 type = HeapRegionType::Survivor; 4761 } else { 4762 type = HeapRegionType::Old; 4763 } 4764 4765 HeapRegion* new_alloc_region = new_region(word_size, 4766 type, 4767 true /* do_expand */, 4768 node_index); 4769 4770 if (new_alloc_region != NULL) { 4771 if (type.is_survivor()) { 4772 new_alloc_region->set_survivor(); 4773 _survivor.add(new_alloc_region); 4774 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4775 } else { 4776 new_alloc_region->set_old(); 4777 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4778 } 4779 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4780 register_region_with_region_attr(new_alloc_region); 4781 _hr_printer.alloc(new_alloc_region); 4782 return new_alloc_region; 4783 } 4784 return NULL; 4785 } 4786 4787 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4788 size_t allocated_bytes, 4789 G1HeapRegionAttr dest) { 4790 _bytes_used_during_gc += allocated_bytes; 4791 if (dest.is_old()) { 4792 old_set_add(alloc_region); 4793 } else { 4794 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4795 _survivor.add_used_bytes(allocated_bytes); 4796 } 4797 4798 bool const during_im = collector_state()->in_concurrent_start_gc(); 4799 if (during_im && allocated_bytes > 0) { 4800 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4801 } 4802 _hr_printer.retire(alloc_region); 4803 } 4804 4805 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4806 bool expanded = false; 4807 uint index = _hrm->find_highest_free(&expanded); 4808 4809 if (index != G1_NO_HRM_INDEX) { 4810 if (expanded) { 4811 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4812 HeapRegion::GrainWords * HeapWordSize); 4813 } 4814 return _hrm->allocate_free_regions_starting_at(index, 1); 4815 } 4816 return NULL; 4817 } 4818 4819 // Optimized nmethod scanning 4820 4821 class RegisterNMethodOopClosure: public OopClosure { 4822 G1CollectedHeap* _g1h; 4823 nmethod* _nm; 4824 4825 template <class T> void do_oop_work(T* p) { 4826 T heap_oop = RawAccess<>::oop_load(p); 4827 if (!CompressedOops::is_null(heap_oop)) { 4828 oop obj = CompressedOops::decode_not_null(heap_oop); 4829 HeapRegion* hr = _g1h->heap_region_containing(obj); 4830 assert(!hr->is_continues_humongous(), 4831 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4832 " starting at " HR_FORMAT, 4833 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4834 4835 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4836 hr->add_strong_code_root_locked(_nm); 4837 } 4838 } 4839 4840 public: 4841 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4842 _g1h(g1h), _nm(nm) {} 4843 4844 void do_oop(oop* p) { do_oop_work(p); } 4845 void do_oop(narrowOop* p) { do_oop_work(p); } 4846 }; 4847 4848 class UnregisterNMethodOopClosure: public OopClosure { 4849 G1CollectedHeap* _g1h; 4850 nmethod* _nm; 4851 4852 template <class T> void do_oop_work(T* p) { 4853 T heap_oop = RawAccess<>::oop_load(p); 4854 if (!CompressedOops::is_null(heap_oop)) { 4855 oop obj = CompressedOops::decode_not_null(heap_oop); 4856 HeapRegion* hr = _g1h->heap_region_containing(obj); 4857 assert(!hr->is_continues_humongous(), 4858 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4859 " starting at " HR_FORMAT, 4860 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4861 4862 hr->remove_strong_code_root(_nm); 4863 } 4864 } 4865 4866 public: 4867 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4868 _g1h(g1h), _nm(nm) {} 4869 4870 void do_oop(oop* p) { do_oop_work(p); } 4871 void do_oop(narrowOop* p) { do_oop_work(p); } 4872 }; 4873 4874 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4875 guarantee(nm != NULL, "sanity"); 4876 RegisterNMethodOopClosure reg_cl(this, nm); 4877 nm->oops_do(®_cl); 4878 } 4879 4880 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4881 guarantee(nm != NULL, "sanity"); 4882 UnregisterNMethodOopClosure reg_cl(this, nm); 4883 nm->oops_do(®_cl, true); 4884 } 4885 4886 void G1CollectedHeap::purge_code_root_memory() { 4887 double purge_start = os::elapsedTime(); 4888 G1CodeRootSet::purge(); 4889 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4890 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4891 } 4892 4893 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4894 G1CollectedHeap* _g1h; 4895 4896 public: 4897 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4898 _g1h(g1h) {} 4899 4900 void do_code_blob(CodeBlob* cb) { 4901 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4902 if (nm == NULL) { 4903 return; 4904 } 4905 4906 _g1h->register_nmethod(nm); 4907 } 4908 }; 4909 4910 void G1CollectedHeap::rebuild_strong_code_roots() { 4911 RebuildStrongCodeRootClosure blob_cl(this); 4912 CodeCache::blobs_do(&blob_cl); 4913 } 4914 4915 void G1CollectedHeap::initialize_serviceability() { 4916 _g1mm->initialize_serviceability(); 4917 } 4918 4919 MemoryUsage G1CollectedHeap::memory_usage() { 4920 return _g1mm->memory_usage(); 4921 } 4922 4923 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4924 return _g1mm->memory_managers(); 4925 } 4926 4927 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4928 return _g1mm->memory_pools(); 4929 } --- EOF ---