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