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/g1MemoryPool.hpp" 51 #include "gc/g1/g1OopClosures.inline.hpp" 52 #include "gc/g1/g1ParallelCleaning.hpp" 53 #include "gc/g1/g1ParScanThreadState.inline.hpp" 54 #include "gc/g1/g1Policy.hpp" 55 #include "gc/g1/g1RedirtyCardsQueue.hpp" 56 #include "gc/g1/g1RegionToSpaceMapper.hpp" 57 #include "gc/g1/g1RemSet.hpp" 58 #include "gc/g1/g1RootClosures.hpp" 59 #include "gc/g1/g1RootProcessor.hpp" 60 #include "gc/g1/g1SATBMarkQueueSet.hpp" 61 #include "gc/g1/g1StringDedup.hpp" 62 #include "gc/g1/g1ThreadLocalData.hpp" 63 #include "gc/g1/g1Trace.hpp" 64 #include "gc/g1/g1YCTypes.hpp" 65 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 66 #include "gc/g1/g1VMOperations.hpp" 67 #include "gc/g1/heapRegion.inline.hpp" 68 #include "gc/g1/heapRegionRemSet.hpp" 69 #include "gc/g1/heapRegionSet.inline.hpp" 70 #include "gc/shared/concurrentGCBreakpoints.hpp" 71 #include "gc/shared/gcBehaviours.hpp" 72 #include "gc/shared/gcHeapSummary.hpp" 73 #include "gc/shared/gcId.hpp" 74 #include "gc/shared/gcLocker.hpp" 75 #include "gc/shared/gcTimer.hpp" 76 #include "gc/shared/gcTraceTime.inline.hpp" 77 #include "gc/shared/generationSpec.hpp" 78 #include "gc/shared/isGCActiveMark.hpp" 79 #include "gc/shared/locationPrinter.inline.hpp" 80 #include "gc/shared/oopStorageParState.hpp" 81 #include "gc/shared/preservedMarks.inline.hpp" 82 #include "gc/shared/suspendibleThreadSet.hpp" 83 #include "gc/shared/referenceProcessor.inline.hpp" 84 #include "gc/shared/taskTerminator.hpp" 85 #include "gc/shared/taskqueue.inline.hpp" 86 #include "gc/shared/weakProcessor.inline.hpp" 87 #include "gc/shared/workerPolicy.hpp" 88 #include "logging/log.hpp" 89 #include "memory/allocation.hpp" 90 #include "memory/iterator.hpp" 91 #include "memory/resourceArea.hpp" 92 #include "memory/universe.hpp" 93 #include "oops/access.inline.hpp" 94 #include "oops/compressedOops.inline.hpp" 95 #include "oops/oop.inline.hpp" 96 #include "runtime/atomic.hpp" 97 #include "runtime/flags/flagSetting.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/bitMap.inline.hpp" 105 #include "utilities/globalDefinitions.hpp" 106 #include "utilities/stack.inline.hpp" 107 108 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 109 110 // INVARIANTS/NOTES 111 // 112 // All allocation activity covered by the G1CollectedHeap interface is 113 // serialized by acquiring the HeapLock. This happens in mem_allocate 114 // and allocate_new_tlab, which are the "entry" points to the 115 // allocation code from the rest of the JVM. (Note that this does not 116 // apply to TLAB allocation, which is not part of this interface: it 117 // is done by clients of this interface.) 118 119 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 120 private: 121 size_t _num_dirtied; 122 G1CollectedHeap* _g1h; 123 G1CardTable* _g1_ct; 124 125 HeapRegion* region_for_card(CardValue* card_ptr) const { 126 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 127 } 128 129 bool will_become_free(HeapRegion* hr) const { 130 // A region will be freed by free_collection_set if the region is in the 131 // collection set and has not had an evacuation failure. 132 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 133 } 134 135 public: 136 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 137 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 138 139 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 140 HeapRegion* hr = region_for_card(card_ptr); 141 142 // Should only dirty cards in regions that won't be freed. 143 if (!will_become_free(hr)) { 144 *card_ptr = G1CardTable::dirty_card_val(); 145 _num_dirtied++; 146 } 147 } 148 149 size_t num_dirtied() const { return _num_dirtied; } 150 }; 151 152 153 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 154 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 155 } 156 157 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 158 // The from card cache is not the memory that is actually committed. So we cannot 159 // take advantage of the zero_filled parameter. 160 reset_from_card_cache(start_idx, num_regions); 161 } 162 163 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 164 Ticks start = Ticks::now(); 165 workers()->run_task(task, workers()->active_workers()); 166 return Ticks::now() - start; 167 } 168 169 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 170 MemRegion mr) { 171 return new HeapRegion(hrs_index, bot(), mr); 172 } 173 174 // Private methods. 175 176 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 177 HeapRegionType type, 178 bool do_expand, 179 uint node_index) { 180 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 181 "the only time we use this to allocate a humongous region is " 182 "when we are allocating a single humongous region"); 183 184 HeapRegion* res = _hrm->allocate_free_region(type, node_index); 185 186 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 187 // Currently, only attempts to allocate GC alloc regions set 188 // do_expand to true. So, we should only reach here during a 189 // safepoint. If this assumption changes we might have to 190 // reconsider the use of _expand_heap_after_alloc_failure. 191 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 192 193 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 194 word_size * HeapWordSize); 195 196 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 197 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 198 word_size * HeapWordSize); 199 if (expand_single_region(node_index)) { 200 // Given that expand_single_region() succeeded in expanding the heap, and we 201 // always expand the heap by an amount aligned to the heap 202 // region size, the free list should in theory not be empty. 203 // In either case allocate_free_region() will check for NULL. 204 res = _hrm->allocate_free_region(type, node_index); 205 } else { 206 _expand_heap_after_alloc_failure = false; 207 } 208 } 209 return res; 210 } 211 212 HeapWord* 213 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 214 uint num_regions, 215 size_t word_size) { 216 assert(first_hr != NULL, "pre-condition"); 217 assert(is_humongous(word_size), "word_size should be humongous"); 218 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 219 220 // Index of last region in the series. 221 uint first = first_hr->hrm_index(); 222 uint last = first + num_regions - 1; 223 224 // We need to initialize the region(s) we just discovered. This is 225 // a bit tricky given that it can happen concurrently with 226 // refinement threads refining cards on these regions and 227 // potentially wanting to refine the BOT as they are scanning 228 // those cards (this can happen shortly after a cleanup; see CR 229 // 6991377). So we have to set up the region(s) carefully and in 230 // a specific order. 231 232 // The word size sum of all the regions we will allocate. 233 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 234 assert(word_size <= word_size_sum, "sanity"); 235 236 // The passed in hr will be the "starts humongous" region. The header 237 // of the new object will be placed at the bottom of this region. 238 HeapWord* new_obj = first_hr->bottom(); 239 // This will be the new top of the new object. 240 HeapWord* obj_top = new_obj + word_size; 241 242 // First, we need to zero the header of the space that we will be 243 // allocating. When we update top further down, some refinement 244 // threads might try to scan the region. By zeroing the header we 245 // ensure that any thread that will try to scan the region will 246 // come across the zero klass word and bail out. 247 // 248 // NOTE: It would not have been correct to have used 249 // CollectedHeap::fill_with_object() and make the space look like 250 // an int array. The thread that is doing the allocation will 251 // later update the object header to a potentially different array 252 // type and, for a very short period of time, the klass and length 253 // fields will be inconsistent. This could cause a refinement 254 // thread to calculate the object size incorrectly. 255 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 256 257 // Next, pad out the unused tail of the last region with filler 258 // objects, for improved usage accounting. 259 // How many words we use for filler objects. 260 size_t word_fill_size = word_size_sum - word_size; 261 262 // How many words memory we "waste" which cannot hold a filler object. 263 size_t words_not_fillable = 0; 264 265 if (word_fill_size >= min_fill_size()) { 266 fill_with_objects(obj_top, word_fill_size); 267 } else if (word_fill_size > 0) { 268 // We have space to fill, but we cannot fit an object there. 269 words_not_fillable = word_fill_size; 270 word_fill_size = 0; 271 } 272 273 // We will set up the first region as "starts humongous". This 274 // will also update the BOT covering all the regions to reflect 275 // that there is a single object that starts at the bottom of the 276 // first region. 277 first_hr->set_starts_humongous(obj_top, word_fill_size); 278 _policy->remset_tracker()->update_at_allocate(first_hr); 279 // Then, if there are any, we will set up the "continues 280 // humongous" regions. 281 HeapRegion* hr = NULL; 282 for (uint i = first + 1; i <= last; ++i) { 283 hr = region_at(i); 284 hr->set_continues_humongous(first_hr); 285 _policy->remset_tracker()->update_at_allocate(hr); 286 } 287 288 // Up to this point no concurrent thread would have been able to 289 // do any scanning on any region in this series. All the top 290 // fields still point to bottom, so the intersection between 291 // [bottom,top] and [card_start,card_end] will be empty. Before we 292 // update the top fields, we'll do a storestore to make sure that 293 // no thread sees the update to top before the zeroing of the 294 // object header and the BOT initialization. 295 OrderAccess::storestore(); 296 297 // Now, we will update the top fields of the "continues humongous" 298 // regions except the last one. 299 for (uint i = first; i < last; ++i) { 300 hr = region_at(i); 301 hr->set_top(hr->end()); 302 } 303 304 hr = region_at(last); 305 // If we cannot fit a filler object, we must set top to the end 306 // of the humongous object, otherwise we cannot iterate the heap 307 // and the BOT will not be complete. 308 hr->set_top(hr->end() - words_not_fillable); 309 310 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 311 "obj_top should be in last region"); 312 313 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 314 315 assert(words_not_fillable == 0 || 316 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 317 "Miscalculation in humongous allocation"); 318 319 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 320 321 for (uint i = first; i <= last; ++i) { 322 hr = region_at(i); 323 _humongous_set.add(hr); 324 _hr_printer.alloc(hr); 325 } 326 327 return new_obj; 328 } 329 330 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 331 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 332 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 333 } 334 335 // If could fit into free regions w/o expansion, try. 336 // Otherwise, if can expand, do so. 337 // Otherwise, if using ex regions might help, try with ex given back. 338 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 339 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 340 341 _verifier->verify_region_sets_optional(); 342 343 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 344 345 // Policy: First try to allocate a humongous object in the free list. 346 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions); 347 if (humongous_start == NULL) { 348 // Policy: We could not find enough regions for the humongous object in the 349 // free list. Look through the heap to find a mix of free and uncommitted regions. 350 // If so, expand the heap and allocate the humongous object. 351 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions); 352 if (humongous_start != NULL) { 353 // We managed to find a region by expanding the heap. 354 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B", 355 word_size * HeapWordSize); 356 policy()->record_new_heap_size(num_regions()); 357 } else { 358 // Policy: Potentially trigger a defragmentation GC. 359 } 360 } 361 362 HeapWord* result = NULL; 363 if (humongous_start != NULL) { 364 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size); 365 assert(result != NULL, "it should always return a valid result"); 366 367 // A successful humongous object allocation changes the used space 368 // information of the old generation so we need to recalculate the 369 // sizes and update the jstat counters here. 370 g1mm()->update_sizes(); 371 } 372 373 _verifier->verify_region_sets_optional(); 374 375 return result; 376 } 377 378 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 379 size_t requested_size, 380 size_t* actual_size) { 381 assert_heap_not_locked_and_not_at_safepoint(); 382 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 383 384 return attempt_allocation(min_size, requested_size, actual_size); 385 } 386 387 HeapWord* 388 G1CollectedHeap::mem_allocate(size_t word_size, 389 bool* gc_overhead_limit_was_exceeded) { 390 assert_heap_not_locked_and_not_at_safepoint(); 391 392 if (is_humongous(word_size)) { 393 return attempt_allocation_humongous(word_size); 394 } 395 size_t dummy = 0; 396 return attempt_allocation(word_size, word_size, &dummy); 397 } 398 399 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 400 ResourceMark rm; // For retrieving the thread names in log messages. 401 402 // Make sure you read the note in attempt_allocation_humongous(). 403 404 assert_heap_not_locked_and_not_at_safepoint(); 405 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 406 "be called for humongous allocation requests"); 407 408 // We should only get here after the first-level allocation attempt 409 // (attempt_allocation()) failed to allocate. 410 411 // We will loop until a) we manage to successfully perform the 412 // allocation or b) we successfully schedule a collection which 413 // fails to perform the allocation. b) is the only case when we'll 414 // return NULL. 415 HeapWord* result = NULL; 416 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 417 bool should_try_gc; 418 uint gc_count_before; 419 420 { 421 MutexLocker x(Heap_lock); 422 result = _allocator->attempt_allocation_locked(word_size); 423 if (result != NULL) { 424 return result; 425 } 426 427 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 428 // This is different to when only GCLocker::needs_gc() is set: try to avoid 429 // waiting because the GCLocker is active to not wait too long. 430 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 431 // No need for an ergo message here, can_expand_young_list() does this when 432 // it returns true. 433 result = _allocator->attempt_allocation_force(word_size); 434 if (result != NULL) { 435 return result; 436 } 437 } 438 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 439 // the GCLocker initiated GC has been performed and then retry. This includes 440 // the case when the GC Locker is not active but has not been performed. 441 should_try_gc = !GCLocker::needs_gc(); 442 // Read the GC count while still holding the Heap_lock. 443 gc_count_before = total_collections(); 444 } 445 446 if (should_try_gc) { 447 bool succeeded; 448 result = do_collection_pause(word_size, gc_count_before, &succeeded, 449 GCCause::_g1_inc_collection_pause); 450 if (result != NULL) { 451 assert(succeeded, "only way to get back a non-NULL result"); 452 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 453 Thread::current()->name(), p2i(result)); 454 return result; 455 } 456 457 if (succeeded) { 458 // We successfully scheduled a collection which failed to allocate. No 459 // point in trying to allocate further. We'll just return NULL. 460 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 461 SIZE_FORMAT " words", Thread::current()->name(), word_size); 462 return NULL; 463 } 464 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 465 Thread::current()->name(), word_size); 466 } else { 467 // Failed to schedule a collection. 468 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 469 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 470 SIZE_FORMAT " words", Thread::current()->name(), word_size); 471 return NULL; 472 } 473 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 474 // The GCLocker is either active or the GCLocker initiated 475 // GC has not yet been performed. Stall until it is and 476 // then retry the allocation. 477 GCLocker::stall_until_clear(); 478 gclocker_retry_count += 1; 479 } 480 481 // We can reach here if we were unsuccessful in scheduling a 482 // collection (because another thread beat us to it) or if we were 483 // stalled due to the GC locker. In either can we should retry the 484 // allocation attempt in case another thread successfully 485 // performed a collection and reclaimed enough space. We do the 486 // first attempt (without holding the Heap_lock) here and the 487 // follow-on attempt will be at the start of the next loop 488 // iteration (after taking the Heap_lock). 489 size_t dummy = 0; 490 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 491 if (result != NULL) { 492 return result; 493 } 494 495 // Give a warning if we seem to be looping forever. 496 if ((QueuedAllocationWarningCount > 0) && 497 (try_count % QueuedAllocationWarningCount == 0)) { 498 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 499 Thread::current()->name(), try_count, word_size); 500 } 501 } 502 503 ShouldNotReachHere(); 504 return NULL; 505 } 506 507 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 508 assert_at_safepoint_on_vm_thread(); 509 if (_archive_allocator == NULL) { 510 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 511 } 512 } 513 514 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 515 // Allocations in archive regions cannot be of a size that would be considered 516 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 517 // may be different at archive-restore time. 518 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 519 } 520 521 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 522 assert_at_safepoint_on_vm_thread(); 523 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 524 if (is_archive_alloc_too_large(word_size)) { 525 return NULL; 526 } 527 return _archive_allocator->archive_mem_allocate(word_size); 528 } 529 530 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 531 size_t end_alignment_in_bytes) { 532 assert_at_safepoint_on_vm_thread(); 533 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 534 535 // Call complete_archive to do the real work, filling in the MemRegion 536 // array with the archive regions. 537 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 538 delete _archive_allocator; 539 _archive_allocator = NULL; 540 } 541 542 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 543 assert(ranges != NULL, "MemRegion array NULL"); 544 assert(count != 0, "No MemRegions provided"); 545 MemRegion reserved = _hrm->reserved(); 546 for (size_t i = 0; i < count; i++) { 547 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 548 return false; 549 } 550 } 551 return true; 552 } 553 554 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 555 size_t count, 556 bool open) { 557 assert(!is_init_completed(), "Expect to be called at JVM init time"); 558 assert(ranges != NULL, "MemRegion array NULL"); 559 assert(count != 0, "No MemRegions provided"); 560 MutexLocker x(Heap_lock); 561 562 MemRegion reserved = _hrm->reserved(); 563 HeapWord* prev_last_addr = NULL; 564 HeapRegion* prev_last_region = NULL; 565 566 // Temporarily disable pretouching of heap pages. This interface is used 567 // when mmap'ing archived heap data in, so pre-touching is wasted. 568 FlagSetting fs(AlwaysPreTouch, false); 569 570 // Enable archive object checking used by G1MarkSweep. We have to let it know 571 // about each archive range, so that objects in those ranges aren't marked. 572 G1ArchiveAllocator::enable_archive_object_check(); 573 574 // For each specified MemRegion range, allocate the corresponding G1 575 // regions and mark them as archive regions. We expect the ranges 576 // in ascending starting address order, without overlap. 577 for (size_t i = 0; i < count; i++) { 578 MemRegion curr_range = ranges[i]; 579 HeapWord* start_address = curr_range.start(); 580 size_t word_size = curr_range.word_size(); 581 HeapWord* last_address = curr_range.last(); 582 size_t commits = 0; 583 584 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 585 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 586 p2i(start_address), p2i(last_address)); 587 guarantee(start_address > prev_last_addr, 588 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 589 p2i(start_address), p2i(prev_last_addr)); 590 prev_last_addr = last_address; 591 592 // Check for ranges that start in the same G1 region in which the previous 593 // range ended, and adjust the start address so we don't try to allocate 594 // the same region again. If the current range is entirely within that 595 // region, skip it, just adjusting the recorded top. 596 HeapRegion* start_region = _hrm->addr_to_region(start_address); 597 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 598 start_address = start_region->end(); 599 if (start_address > last_address) { 600 increase_used(word_size * HeapWordSize); 601 start_region->set_top(last_address + 1); 602 continue; 603 } 604 start_region->set_top(start_address); 605 curr_range = MemRegion(start_address, last_address + 1); 606 start_region = _hrm->addr_to_region(start_address); 607 } 608 609 // Perform the actual region allocation, exiting if it fails. 610 // Then note how much new space we have allocated. 611 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 612 return false; 613 } 614 increase_used(word_size * HeapWordSize); 615 if (commits != 0) { 616 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 617 HeapRegion::GrainWords * HeapWordSize * commits); 618 619 } 620 621 // Mark each G1 region touched by the range as archive, add it to 622 // the old set, and set top. 623 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 624 HeapRegion* last_region = _hrm->addr_to_region(last_address); 625 prev_last_region = last_region; 626 627 while (curr_region != NULL) { 628 assert(curr_region->is_empty() && !curr_region->is_pinned(), 629 "Region already in use (index %u)", curr_region->hrm_index()); 630 if (open) { 631 curr_region->set_open_archive(); 632 } else { 633 curr_region->set_closed_archive(); 634 } 635 _hr_printer.alloc(curr_region); 636 _archive_set.add(curr_region); 637 HeapWord* top; 638 HeapRegion* next_region; 639 if (curr_region != last_region) { 640 top = curr_region->end(); 641 next_region = _hrm->next_region_in_heap(curr_region); 642 } else { 643 top = last_address + 1; 644 next_region = NULL; 645 } 646 curr_region->set_top(top); 647 curr_region = next_region; 648 } 649 650 // Notify mark-sweep of the archive 651 G1ArchiveAllocator::set_range_archive(curr_range, open); 652 } 653 return true; 654 } 655 656 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 657 assert(!is_init_completed(), "Expect to be called at JVM init time"); 658 assert(ranges != NULL, "MemRegion array NULL"); 659 assert(count != 0, "No MemRegions provided"); 660 MemRegion reserved = _hrm->reserved(); 661 HeapWord *prev_last_addr = NULL; 662 HeapRegion* prev_last_region = NULL; 663 664 // For each MemRegion, create filler objects, if needed, in the G1 regions 665 // that contain the address range. The address range actually within the 666 // MemRegion will not be modified. That is assumed to have been initialized 667 // elsewhere, probably via an mmap of archived heap data. 668 MutexLocker x(Heap_lock); 669 for (size_t i = 0; i < count; i++) { 670 HeapWord* start_address = ranges[i].start(); 671 HeapWord* last_address = ranges[i].last(); 672 673 assert(reserved.contains(start_address) && reserved.contains(last_address), 674 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 675 p2i(start_address), p2i(last_address)); 676 assert(start_address > prev_last_addr, 677 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 678 p2i(start_address), p2i(prev_last_addr)); 679 680 HeapRegion* start_region = _hrm->addr_to_region(start_address); 681 HeapRegion* last_region = _hrm->addr_to_region(last_address); 682 HeapWord* bottom_address = start_region->bottom(); 683 684 // Check for a range beginning in the same region in which the 685 // previous one ended. 686 if (start_region == prev_last_region) { 687 bottom_address = prev_last_addr + 1; 688 } 689 690 // Verify that the regions were all marked as archive regions by 691 // alloc_archive_regions. 692 HeapRegion* curr_region = start_region; 693 while (curr_region != NULL) { 694 guarantee(curr_region->is_archive(), 695 "Expected archive region at index %u", curr_region->hrm_index()); 696 if (curr_region != last_region) { 697 curr_region = _hrm->next_region_in_heap(curr_region); 698 } else { 699 curr_region = NULL; 700 } 701 } 702 703 prev_last_addr = last_address; 704 prev_last_region = last_region; 705 706 // Fill the memory below the allocated range with dummy object(s), 707 // if the region bottom does not match the range start, or if the previous 708 // range ended within the same G1 region, and there is a gap. 709 if (start_address != bottom_address) { 710 size_t fill_size = pointer_delta(start_address, bottom_address); 711 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 712 increase_used(fill_size * HeapWordSize); 713 } 714 } 715 } 716 717 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 718 size_t desired_word_size, 719 size_t* actual_word_size) { 720 assert_heap_not_locked_and_not_at_safepoint(); 721 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 722 "be called for humongous allocation requests"); 723 724 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 725 726 if (result == NULL) { 727 *actual_word_size = desired_word_size; 728 result = attempt_allocation_slow(desired_word_size); 729 } 730 731 assert_heap_not_locked(); 732 if (result != NULL) { 733 assert(*actual_word_size != 0, "Actual size must have been set here"); 734 dirty_young_block(result, *actual_word_size); 735 } else { 736 *actual_word_size = 0; 737 } 738 739 return result; 740 } 741 742 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 743 assert(!is_init_completed(), "Expect to be called at JVM init time"); 744 assert(ranges != NULL, "MemRegion array NULL"); 745 assert(count != 0, "No MemRegions provided"); 746 MemRegion reserved = _hrm->reserved(); 747 HeapWord* prev_last_addr = NULL; 748 HeapRegion* prev_last_region = NULL; 749 size_t size_used = 0; 750 size_t uncommitted_regions = 0; 751 752 // For each Memregion, free the G1 regions that constitute it, and 753 // notify mark-sweep that the range is no longer to be considered 'archive.' 754 MutexLocker x(Heap_lock); 755 for (size_t i = 0; i < count; i++) { 756 HeapWord* start_address = ranges[i].start(); 757 HeapWord* last_address = ranges[i].last(); 758 759 assert(reserved.contains(start_address) && reserved.contains(last_address), 760 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 761 p2i(start_address), p2i(last_address)); 762 assert(start_address > prev_last_addr, 763 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 764 p2i(start_address), p2i(prev_last_addr)); 765 size_used += ranges[i].byte_size(); 766 prev_last_addr = last_address; 767 768 HeapRegion* start_region = _hrm->addr_to_region(start_address); 769 HeapRegion* last_region = _hrm->addr_to_region(last_address); 770 771 // Check for ranges that start in the same G1 region in which the previous 772 // range ended, and adjust the start address so we don't try to free 773 // the same region again. If the current range is entirely within that 774 // region, skip it. 775 if (start_region == prev_last_region) { 776 start_address = start_region->end(); 777 if (start_address > last_address) { 778 continue; 779 } 780 start_region = _hrm->addr_to_region(start_address); 781 } 782 prev_last_region = last_region; 783 784 // After verifying that each region was marked as an archive region by 785 // alloc_archive_regions, set it free and empty and uncommit it. 786 HeapRegion* curr_region = start_region; 787 while (curr_region != NULL) { 788 guarantee(curr_region->is_archive(), 789 "Expected archive region at index %u", curr_region->hrm_index()); 790 uint curr_index = curr_region->hrm_index(); 791 _archive_set.remove(curr_region); 792 curr_region->set_free(); 793 curr_region->set_top(curr_region->bottom()); 794 if (curr_region != last_region) { 795 curr_region = _hrm->next_region_in_heap(curr_region); 796 } else { 797 curr_region = NULL; 798 } 799 _hrm->shrink_at(curr_index, 1); 800 uncommitted_regions++; 801 } 802 803 // Notify mark-sweep that this is no longer an archive range. 804 G1ArchiveAllocator::clear_range_archive(ranges[i]); 805 } 806 807 if (uncommitted_regions != 0) { 808 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 809 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 810 } 811 decrease_used(size_used); 812 } 813 814 oop G1CollectedHeap::materialize_archived_object(oop obj) { 815 assert(obj != NULL, "archived obj is NULL"); 816 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 817 818 // Loading an archived object makes it strongly reachable. If it is 819 // loaded during concurrent marking, it must be enqueued to the SATB 820 // queue, shading the previously white object gray. 821 G1BarrierSet::enqueue(obj); 822 823 return obj; 824 } 825 826 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 827 ResourceMark rm; // For retrieving the thread names in log messages. 828 829 // The structure of this method has a lot of similarities to 830 // attempt_allocation_slow(). The reason these two were not merged 831 // into a single one is that such a method would require several "if 832 // allocation is not humongous do this, otherwise do that" 833 // conditional paths which would obscure its flow. In fact, an early 834 // version of this code did use a unified method which was harder to 835 // follow and, as a result, it had subtle bugs that were hard to 836 // track down. So keeping these two methods separate allows each to 837 // be more readable. It will be good to keep these two in sync as 838 // much as possible. 839 840 assert_heap_not_locked_and_not_at_safepoint(); 841 assert(is_humongous(word_size), "attempt_allocation_humongous() " 842 "should only be called for humongous allocations"); 843 844 // Humongous objects can exhaust the heap quickly, so we should check if we 845 // need to start a marking cycle at each humongous object allocation. We do 846 // the check before we do the actual allocation. The reason for doing it 847 // before the allocation is that we avoid having to keep track of the newly 848 // allocated memory while we do a GC. 849 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 850 word_size)) { 851 collect(GCCause::_g1_humongous_allocation); 852 } 853 854 // We will loop until a) we manage to successfully perform the 855 // allocation or b) we successfully schedule a collection which 856 // fails to perform the allocation. b) is the only case when we'll 857 // return NULL. 858 HeapWord* result = NULL; 859 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 860 bool should_try_gc; 861 uint gc_count_before; 862 863 864 { 865 MutexLocker x(Heap_lock); 866 867 // Given that humongous objects are not allocated in young 868 // regions, we'll first try to do the allocation without doing a 869 // collection hoping that there's enough space in the heap. 870 result = humongous_obj_allocate(word_size); 871 if (result != NULL) { 872 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 873 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 874 return result; 875 } 876 877 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 878 // the GCLocker initiated GC has been performed and then retry. This includes 879 // the case when the GC Locker is not active but has not been performed. 880 should_try_gc = !GCLocker::needs_gc(); 881 // Read the GC count while still holding the Heap_lock. 882 gc_count_before = total_collections(); 883 } 884 885 if (should_try_gc) { 886 bool succeeded; 887 result = do_collection_pause(word_size, gc_count_before, &succeeded, 888 GCCause::_g1_humongous_allocation); 889 if (result != NULL) { 890 assert(succeeded, "only way to get back a non-NULL result"); 891 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 892 Thread::current()->name(), p2i(result)); 893 return result; 894 } 895 896 if (succeeded) { 897 // We successfully scheduled a collection which failed to allocate. No 898 // point in trying to allocate further. We'll just return NULL. 899 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 900 SIZE_FORMAT " words", Thread::current()->name(), word_size); 901 return NULL; 902 } 903 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 904 Thread::current()->name(), word_size); 905 } else { 906 // Failed to schedule a collection. 907 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 908 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 909 SIZE_FORMAT " words", Thread::current()->name(), word_size); 910 return NULL; 911 } 912 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 913 // The GCLocker is either active or the GCLocker initiated 914 // GC has not yet been performed. Stall until it is and 915 // then retry the allocation. 916 GCLocker::stall_until_clear(); 917 gclocker_retry_count += 1; 918 } 919 920 921 // We can reach here if we were unsuccessful in scheduling a 922 // collection (because another thread beat us to it) or if we were 923 // stalled due to the GC locker. In either can we should retry the 924 // allocation attempt in case another thread successfully 925 // performed a collection and reclaimed enough space. 926 // Humongous object allocation always needs a lock, so we wait for the retry 927 // in the next iteration of the loop, unlike for the regular iteration case. 928 // Give a warning if we seem to be looping forever. 929 930 if ((QueuedAllocationWarningCount > 0) && 931 (try_count % QueuedAllocationWarningCount == 0)) { 932 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 933 Thread::current()->name(), try_count, word_size); 934 } 935 } 936 937 ShouldNotReachHere(); 938 return NULL; 939 } 940 941 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 942 bool expect_null_mutator_alloc_region) { 943 assert_at_safepoint_on_vm_thread(); 944 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 945 "the current alloc region was unexpectedly found to be non-NULL"); 946 947 if (!is_humongous(word_size)) { 948 return _allocator->attempt_allocation_locked(word_size); 949 } else { 950 HeapWord* result = humongous_obj_allocate(word_size); 951 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 952 collector_state()->set_initiate_conc_mark_if_possible(true); 953 } 954 return result; 955 } 956 957 ShouldNotReachHere(); 958 } 959 960 class PostCompactionPrinterClosure: public HeapRegionClosure { 961 private: 962 G1HRPrinter* _hr_printer; 963 public: 964 bool do_heap_region(HeapRegion* hr) { 965 assert(!hr->is_young(), "not expecting to find young regions"); 966 _hr_printer->post_compaction(hr); 967 return false; 968 } 969 970 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 971 : _hr_printer(hr_printer) { } 972 }; 973 974 void G1CollectedHeap::print_hrm_post_compaction() { 975 if (_hr_printer.is_active()) { 976 PostCompactionPrinterClosure cl(hr_printer()); 977 heap_region_iterate(&cl); 978 } 979 } 980 981 void G1CollectedHeap::abort_concurrent_cycle() { 982 // If we start the compaction before the CM threads finish 983 // scanning the root regions we might trip them over as we'll 984 // be moving objects / updating references. So let's wait until 985 // they are done. By telling them to abort, they should complete 986 // early. 987 _cm->root_regions()->abort(); 988 _cm->root_regions()->wait_until_scan_finished(); 989 990 // Disable discovery and empty the discovered lists 991 // for the CM ref processor. 992 _ref_processor_cm->disable_discovery(); 993 _ref_processor_cm->abandon_partial_discovery(); 994 _ref_processor_cm->verify_no_references_recorded(); 995 996 // Abandon current iterations of concurrent marking and concurrent 997 // refinement, if any are in progress. 998 concurrent_mark()->concurrent_cycle_abort(); 999 } 1000 1001 void G1CollectedHeap::prepare_heap_for_full_collection() { 1002 // Make sure we'll choose a new allocation region afterwards. 1003 _allocator->release_mutator_alloc_regions(); 1004 _allocator->abandon_gc_alloc_regions(); 1005 1006 // We may have added regions to the current incremental collection 1007 // set between the last GC or pause and now. We need to clear the 1008 // incremental collection set and then start rebuilding it afresh 1009 // after this full GC. 1010 abandon_collection_set(collection_set()); 1011 1012 tear_down_region_sets(false /* free_list_only */); 1013 1014 hrm()->prepare_for_full_collection_start(); 1015 } 1016 1017 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1018 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1019 assert_used_and_recalculate_used_equal(this); 1020 _verifier->verify_region_sets_optional(); 1021 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1022 _verifier->check_bitmaps("Full GC Start"); 1023 } 1024 1025 void G1CollectedHeap::prepare_heap_for_mutators() { 1026 hrm()->prepare_for_full_collection_end(); 1027 1028 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1029 ClassLoaderDataGraph::purge(); 1030 MetaspaceUtils::verify_metrics(); 1031 1032 // Prepare heap for normal collections. 1033 assert(num_free_regions() == 0, "we should not have added any free regions"); 1034 rebuild_region_sets(false /* free_list_only */); 1035 abort_refinement(); 1036 resize_heap_if_necessary(); 1037 1038 // Rebuild the strong code root lists for each region 1039 rebuild_strong_code_roots(); 1040 1041 // Purge code root memory 1042 purge_code_root_memory(); 1043 1044 // Start a new incremental collection set for the next pause 1045 start_new_collection_set(); 1046 1047 _allocator->init_mutator_alloc_regions(); 1048 1049 // Post collection state updates. 1050 MetaspaceGC::compute_new_size(); 1051 } 1052 1053 void G1CollectedHeap::abort_refinement() { 1054 if (_hot_card_cache->use_cache()) { 1055 _hot_card_cache->reset_hot_cache(); 1056 } 1057 1058 // Discard all remembered set updates and reset refinement statistics. 1059 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1060 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1061 "DCQS should be empty"); 1062 concurrent_refine()->get_and_reset_refinement_stats(); 1063 } 1064 1065 void G1CollectedHeap::verify_after_full_collection() { 1066 _hrm->verify_optional(); 1067 _verifier->verify_region_sets_optional(); 1068 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1069 // Clear the previous marking bitmap, if needed for bitmap verification. 1070 // Note we cannot do this when we clear the next marking bitmap in 1071 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1072 // objects marked during a full GC against the previous bitmap. 1073 // But we need to clear it before calling check_bitmaps below since 1074 // the full GC has compacted objects and updated TAMS but not updated 1075 // the prev bitmap. 1076 if (G1VerifyBitmaps) { 1077 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1078 _cm->clear_prev_bitmap(workers()); 1079 } 1080 // This call implicitly verifies that the next bitmap is clear after Full GC. 1081 _verifier->check_bitmaps("Full GC End"); 1082 1083 // At this point there should be no regions in the 1084 // entire heap tagged as young. 1085 assert(check_young_list_empty(), "young list should be empty at this point"); 1086 1087 // Note: since we've just done a full GC, concurrent 1088 // marking is no longer active. Therefore we need not 1089 // re-enable reference discovery for the CM ref processor. 1090 // That will be done at the start of the next marking cycle. 1091 // We also know that the STW processor should no longer 1092 // discover any new references. 1093 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1094 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1095 _ref_processor_stw->verify_no_references_recorded(); 1096 _ref_processor_cm->verify_no_references_recorded(); 1097 } 1098 1099 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1100 // Post collection logging. 1101 // We should do this after we potentially resize the heap so 1102 // that all the COMMIT / UNCOMMIT events are generated before 1103 // the compaction events. 1104 print_hrm_post_compaction(); 1105 heap_transition->print(); 1106 print_heap_after_gc(); 1107 print_heap_regions(); 1108 } 1109 1110 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1111 bool clear_all_soft_refs) { 1112 assert_at_safepoint_on_vm_thread(); 1113 1114 if (GCLocker::check_active_before_gc()) { 1115 // Full GC was not completed. 1116 return false; 1117 } 1118 1119 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1120 soft_ref_policy()->should_clear_all_soft_refs(); 1121 1122 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1123 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1124 1125 collector.prepare_collection(); 1126 collector.collect(); 1127 collector.complete_collection(); 1128 1129 // Full collection was successfully completed. 1130 return true; 1131 } 1132 1133 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1134 // Currently, there is no facility in the do_full_collection(bool) API to notify 1135 // the caller that the collection did not succeed (e.g., because it was locked 1136 // out by the GC locker). So, right now, we'll ignore the return value. 1137 bool dummy = do_full_collection(true, /* explicit_gc */ 1138 clear_all_soft_refs); 1139 } 1140 1141 void G1CollectedHeap::resize_heap_if_necessary() { 1142 assert_at_safepoint_on_vm_thread(); 1143 1144 // Capacity, free and used after the GC counted as full regions to 1145 // include the waste in the following calculations. 1146 const size_t capacity_after_gc = capacity(); 1147 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1148 1149 // This is enforced in arguments.cpp. 1150 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1151 "otherwise the code below doesn't make sense"); 1152 1153 // We don't have floating point command-line arguments 1154 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1155 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1156 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1157 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1158 1159 // We have to be careful here as these two calculations can overflow 1160 // 32-bit size_t's. 1161 double used_after_gc_d = (double) used_after_gc; 1162 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1163 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1164 1165 // Let's make sure that they are both under the max heap size, which 1166 // by default will make them fit into a size_t. 1167 double desired_capacity_upper_bound = (double) MaxHeapSize; 1168 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1169 desired_capacity_upper_bound); 1170 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1171 desired_capacity_upper_bound); 1172 1173 // We can now safely turn them into size_t's. 1174 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1175 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1176 1177 // This assert only makes sense here, before we adjust them 1178 // with respect to the min and max heap size. 1179 assert(minimum_desired_capacity <= maximum_desired_capacity, 1180 "minimum_desired_capacity = " SIZE_FORMAT ", " 1181 "maximum_desired_capacity = " SIZE_FORMAT, 1182 minimum_desired_capacity, maximum_desired_capacity); 1183 1184 // Should not be greater than the heap max size. No need to adjust 1185 // it with respect to the heap min size as it's a lower bound (i.e., 1186 // we'll try to make the capacity larger than it, not smaller). 1187 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1188 // Should not be less than the heap min size. No need to adjust it 1189 // with respect to the heap max size as it's an upper bound (i.e., 1190 // we'll try to make the capacity smaller than it, not greater). 1191 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1192 1193 if (capacity_after_gc < minimum_desired_capacity) { 1194 // Don't expand unless it's significant 1195 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1196 1197 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1198 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1199 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1200 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1201 1202 expand(expand_bytes, _workers); 1203 1204 // No expansion, now see if we want to shrink 1205 } else if (capacity_after_gc > maximum_desired_capacity) { 1206 // Capacity too large, compute shrinking size 1207 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1208 1209 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1210 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1211 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1212 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1213 1214 shrink(shrink_bytes); 1215 } 1216 } 1217 1218 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1219 bool do_gc, 1220 bool clear_all_soft_refs, 1221 bool expect_null_mutator_alloc_region, 1222 bool* gc_succeeded) { 1223 *gc_succeeded = true; 1224 // Let's attempt the allocation first. 1225 HeapWord* result = 1226 attempt_allocation_at_safepoint(word_size, 1227 expect_null_mutator_alloc_region); 1228 if (result != NULL) { 1229 return result; 1230 } 1231 1232 // In a G1 heap, we're supposed to keep allocation from failing by 1233 // incremental pauses. Therefore, at least for now, we'll favor 1234 // expansion over collection. (This might change in the future if we can 1235 // do something smarter than full collection to satisfy a failed alloc.) 1236 result = expand_and_allocate(word_size); 1237 if (result != NULL) { 1238 return result; 1239 } 1240 1241 if (do_gc) { 1242 // Expansion didn't work, we'll try to do a Full GC. 1243 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1244 clear_all_soft_refs); 1245 } 1246 1247 return NULL; 1248 } 1249 1250 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1251 bool* succeeded) { 1252 assert_at_safepoint_on_vm_thread(); 1253 1254 // Attempts to allocate followed by Full GC. 1255 HeapWord* result = 1256 satisfy_failed_allocation_helper(word_size, 1257 true, /* do_gc */ 1258 false, /* clear_all_soft_refs */ 1259 false, /* expect_null_mutator_alloc_region */ 1260 succeeded); 1261 1262 if (result != NULL || !*succeeded) { 1263 return result; 1264 } 1265 1266 // Attempts to allocate followed by Full GC that will collect all soft references. 1267 result = satisfy_failed_allocation_helper(word_size, 1268 true, /* do_gc */ 1269 true, /* clear_all_soft_refs */ 1270 true, /* expect_null_mutator_alloc_region */ 1271 succeeded); 1272 1273 if (result != NULL || !*succeeded) { 1274 return result; 1275 } 1276 1277 // Attempts to allocate, no GC 1278 result = satisfy_failed_allocation_helper(word_size, 1279 false, /* do_gc */ 1280 false, /* clear_all_soft_refs */ 1281 true, /* expect_null_mutator_alloc_region */ 1282 succeeded); 1283 1284 if (result != NULL) { 1285 return result; 1286 } 1287 1288 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1289 "Flag should have been handled and cleared prior to this point"); 1290 1291 // What else? We might try synchronous finalization later. If the total 1292 // space available is large enough for the allocation, then a more 1293 // complete compaction phase than we've tried so far might be 1294 // appropriate. 1295 return NULL; 1296 } 1297 1298 // Attempting to expand the heap sufficiently 1299 // to support an allocation of the given "word_size". If 1300 // successful, perform the allocation and return the address of the 1301 // allocated block, or else "NULL". 1302 1303 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1304 assert_at_safepoint_on_vm_thread(); 1305 1306 _verifier->verify_region_sets_optional(); 1307 1308 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1309 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1310 word_size * HeapWordSize); 1311 1312 1313 if (expand(expand_bytes, _workers)) { 1314 _hrm->verify_optional(); 1315 _verifier->verify_region_sets_optional(); 1316 return attempt_allocation_at_safepoint(word_size, 1317 false /* expect_null_mutator_alloc_region */); 1318 } 1319 return NULL; 1320 } 1321 1322 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1323 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1324 aligned_expand_bytes = align_up(aligned_expand_bytes, 1325 HeapRegion::GrainBytes); 1326 1327 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1328 expand_bytes, aligned_expand_bytes); 1329 1330 if (is_maximal_no_gc()) { 1331 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1332 return false; 1333 } 1334 1335 double expand_heap_start_time_sec = os::elapsedTime(); 1336 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1337 assert(regions_to_expand > 0, "Must expand by at least one region"); 1338 1339 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1340 if (expand_time_ms != NULL) { 1341 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1342 } 1343 1344 if (expanded_by > 0) { 1345 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1346 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1347 policy()->record_new_heap_size(num_regions()); 1348 } else { 1349 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1350 1351 // The expansion of the virtual storage space was unsuccessful. 1352 // Let's see if it was because we ran out of swap. 1353 if (G1ExitOnExpansionFailure && 1354 _hrm->available() >= regions_to_expand) { 1355 // We had head room... 1356 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1357 } 1358 } 1359 return regions_to_expand > 0; 1360 } 1361 1362 bool G1CollectedHeap::expand_single_region(uint node_index) { 1363 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1364 1365 if (expanded_by == 0) { 1366 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1367 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1368 return false; 1369 } 1370 1371 policy()->record_new_heap_size(num_regions()); 1372 return true; 1373 } 1374 1375 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1376 size_t aligned_shrink_bytes = 1377 ReservedSpace::page_align_size_down(shrink_bytes); 1378 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1379 HeapRegion::GrainBytes); 1380 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1381 1382 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1383 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1384 1385 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", 1386 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1387 if (num_regions_removed > 0) { 1388 policy()->record_new_heap_size(num_regions()); 1389 } else { 1390 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1391 } 1392 } 1393 1394 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1395 _verifier->verify_region_sets_optional(); 1396 1397 // We should only reach here at the end of a Full GC or during Remark which 1398 // means we should not not be holding to any GC alloc regions. The method 1399 // below will make sure of that and do any remaining clean up. 1400 _allocator->abandon_gc_alloc_regions(); 1401 1402 // Instead of tearing down / rebuilding the free lists here, we 1403 // could instead use the remove_all_pending() method on free_list to 1404 // remove only the ones that we need to remove. 1405 tear_down_region_sets(true /* free_list_only */); 1406 shrink_helper(shrink_bytes); 1407 rebuild_region_sets(true /* free_list_only */); 1408 1409 _hrm->verify_optional(); 1410 _verifier->verify_region_sets_optional(); 1411 } 1412 1413 class OldRegionSetChecker : public HeapRegionSetChecker { 1414 public: 1415 void check_mt_safety() { 1416 // Master Old Set MT safety protocol: 1417 // (a) If we're at a safepoint, operations on the master old set 1418 // should be invoked: 1419 // - by the VM thread (which will serialize them), or 1420 // - by the GC workers while holding the FreeList_lock, if we're 1421 // at a safepoint for an evacuation pause (this lock is taken 1422 // anyway when an GC alloc region is retired so that a new one 1423 // is allocated from the free list), or 1424 // - by the GC workers while holding the OldSets_lock, if we're at a 1425 // safepoint for a cleanup pause. 1426 // (b) If we're not at a safepoint, operations on the master old set 1427 // should be invoked while holding the Heap_lock. 1428 1429 if (SafepointSynchronize::is_at_safepoint()) { 1430 guarantee(Thread::current()->is_VM_thread() || 1431 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1432 "master old set MT safety protocol at a safepoint"); 1433 } else { 1434 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1435 } 1436 } 1437 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1438 const char* get_description() { return "Old Regions"; } 1439 }; 1440 1441 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1442 public: 1443 void check_mt_safety() { 1444 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1445 "May only change archive regions during initialization or safepoint."); 1446 } 1447 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1448 const char* get_description() { return "Archive Regions"; } 1449 }; 1450 1451 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1452 public: 1453 void check_mt_safety() { 1454 // Humongous Set MT safety protocol: 1455 // (a) If we're at a safepoint, operations on the master humongous 1456 // set should be invoked by either the VM thread (which will 1457 // serialize them) or by the GC workers while holding the 1458 // OldSets_lock. 1459 // (b) If we're not at a safepoint, operations on the master 1460 // humongous set should be invoked while holding the Heap_lock. 1461 1462 if (SafepointSynchronize::is_at_safepoint()) { 1463 guarantee(Thread::current()->is_VM_thread() || 1464 OldSets_lock->owned_by_self(), 1465 "master humongous set MT safety protocol at a safepoint"); 1466 } else { 1467 guarantee(Heap_lock->owned_by_self(), 1468 "master humongous set MT safety protocol outside a safepoint"); 1469 } 1470 } 1471 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1472 const char* get_description() { return "Humongous Regions"; } 1473 }; 1474 1475 G1CollectedHeap::G1CollectedHeap() : 1476 CollectedHeap(), 1477 _young_gen_sampling_thread(NULL), 1478 _workers(NULL), 1479 _card_table(NULL), 1480 _soft_ref_policy(), 1481 _old_set("Old Region Set", new OldRegionSetChecker()), 1482 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1483 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1484 _bot(NULL), 1485 _listener(), 1486 _numa(G1NUMA::create()), 1487 _hrm(NULL), 1488 _allocator(NULL), 1489 _verifier(NULL), 1490 _summary_bytes_used(0), 1491 _bytes_used_during_gc(0), 1492 _archive_allocator(NULL), 1493 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1494 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1495 _expand_heap_after_alloc_failure(true), 1496 _g1mm(NULL), 1497 _humongous_reclaim_candidates(), 1498 _has_humongous_reclaim_candidates(false), 1499 _hr_printer(), 1500 _collector_state(), 1501 _old_marking_cycles_started(0), 1502 _old_marking_cycles_completed(0), 1503 _eden(), 1504 _survivor(), 1505 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1506 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1507 _policy(G1Policy::create_policy(_gc_timer_stw)), 1508 _heap_sizing_policy(NULL), 1509 _collection_set(this, _policy), 1510 _hot_card_cache(NULL), 1511 _rem_set(NULL), 1512 _cm(NULL), 1513 _cm_thread(NULL), 1514 _cr(NULL), 1515 _task_queues(NULL), 1516 _evacuation_failed(false), 1517 _evacuation_failed_info_array(NULL), 1518 _preserved_marks_set(true /* in_c_heap */), 1519 #ifndef PRODUCT 1520 _evacuation_failure_alot_for_current_gc(false), 1521 _evacuation_failure_alot_gc_number(0), 1522 _evacuation_failure_alot_count(0), 1523 #endif 1524 _ref_processor_stw(NULL), 1525 _is_alive_closure_stw(this), 1526 _is_subject_to_discovery_stw(this), 1527 _ref_processor_cm(NULL), 1528 _is_alive_closure_cm(this), 1529 _is_subject_to_discovery_cm(this), 1530 _region_attr() { 1531 1532 _verifier = new G1HeapVerifier(this); 1533 1534 _allocator = new G1Allocator(this); 1535 1536 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1537 1538 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1539 1540 // Override the default _filler_array_max_size so that no humongous filler 1541 // objects are created. 1542 _filler_array_max_size = _humongous_object_threshold_in_words; 1543 1544 uint n_queues = ParallelGCThreads; 1545 _task_queues = new RefToScanQueueSet(n_queues); 1546 1547 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1548 1549 for (uint i = 0; i < n_queues; i++) { 1550 RefToScanQueue* q = new RefToScanQueue(); 1551 q->initialize(); 1552 _task_queues->register_queue(i, q); 1553 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1554 } 1555 1556 // Initialize the G1EvacuationFailureALot counters and flags. 1557 NOT_PRODUCT(reset_evacuation_should_fail();) 1558 _gc_tracer_stw->initialize(); 1559 1560 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1561 } 1562 1563 static size_t actual_reserved_page_size(ReservedSpace rs) { 1564 size_t page_size = os::vm_page_size(); 1565 if (UseLargePages) { 1566 // There are two ways to manage large page memory. 1567 // 1. OS supports committing large page memory. 1568 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1569 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1570 // we reserved memory without large page. 1571 if (os::can_commit_large_page_memory() || rs.special()) { 1572 // An alignment at ReservedSpace comes from preferred page size or 1573 // heap alignment, and if the alignment came from heap alignment, it could be 1574 // larger than large pages size. So need to cap with the large page size. 1575 page_size = MIN2(rs.alignment(), os::large_page_size()); 1576 } 1577 } 1578 1579 return page_size; 1580 } 1581 1582 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1583 size_t size, 1584 size_t translation_factor) { 1585 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1586 // Allocate a new reserved space, preferring to use large pages. 1587 ReservedSpace rs(size, preferred_page_size); 1588 size_t page_size = actual_reserved_page_size(rs); 1589 G1RegionToSpaceMapper* result = 1590 G1RegionToSpaceMapper::create_mapper(rs, 1591 size, 1592 page_size, 1593 HeapRegion::GrainBytes, 1594 translation_factor, 1595 mtGC); 1596 1597 os::trace_page_sizes_for_requested_size(description, 1598 size, 1599 preferred_page_size, 1600 page_size, 1601 rs.base(), 1602 rs.size()); 1603 1604 return result; 1605 } 1606 1607 jint G1CollectedHeap::initialize_concurrent_refinement() { 1608 jint ecode = JNI_OK; 1609 _cr = G1ConcurrentRefine::create(&ecode); 1610 return ecode; 1611 } 1612 1613 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1614 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1615 if (_young_gen_sampling_thread->osthread() == NULL) { 1616 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1617 return JNI_ENOMEM; 1618 } 1619 return JNI_OK; 1620 } 1621 1622 jint G1CollectedHeap::initialize() { 1623 1624 // Necessary to satisfy locking discipline assertions. 1625 1626 MutexLocker x(Heap_lock); 1627 1628 // While there are no constraints in the GC code that HeapWordSize 1629 // be any particular value, there are multiple other areas in the 1630 // system which believe this to be true (e.g. oop->object_size in some 1631 // cases incorrectly returns the size in wordSize units rather than 1632 // HeapWordSize). 1633 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1634 1635 size_t init_byte_size = InitialHeapSize; 1636 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1637 1638 // Ensure that the sizes are properly aligned. 1639 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1640 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1641 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1642 1643 // Reserve the maximum. 1644 1645 // When compressed oops are enabled, the preferred heap base 1646 // is calculated by subtracting the requested size from the 1647 // 32Gb boundary and using the result as the base address for 1648 // heap reservation. If the requested size is not aligned to 1649 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1650 // into the ReservedHeapSpace constructor) then the actual 1651 // base of the reserved heap may end up differing from the 1652 // address that was requested (i.e. the preferred heap base). 1653 // If this happens then we could end up using a non-optimal 1654 // compressed oops mode. 1655 1656 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1657 HeapAlignment); 1658 1659 initialize_reserved_region(heap_rs); 1660 1661 // Create the barrier set for the entire reserved region. 1662 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1663 ct->initialize(); 1664 G1BarrierSet* bs = new G1BarrierSet(ct); 1665 bs->initialize(); 1666 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1667 BarrierSet::set_barrier_set(bs); 1668 _card_table = ct; 1669 1670 { 1671 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1672 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1673 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1674 } 1675 1676 // Create the hot card cache. 1677 _hot_card_cache = new G1HotCardCache(this); 1678 1679 // Carve out the G1 part of the heap. 1680 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1681 size_t page_size = actual_reserved_page_size(heap_rs); 1682 G1RegionToSpaceMapper* heap_storage = 1683 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1684 g1_rs.size(), 1685 page_size, 1686 HeapRegion::GrainBytes, 1687 1, 1688 mtJavaHeap); 1689 if(heap_storage == NULL) { 1690 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1691 return JNI_ERR; 1692 } 1693 1694 os::trace_page_sizes("Heap", 1695 MinHeapSize, 1696 reserved_byte_size, 1697 page_size, 1698 heap_rs.base(), 1699 heap_rs.size()); 1700 heap_storage->set_mapping_changed_listener(&_listener); 1701 1702 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1703 G1RegionToSpaceMapper* bot_storage = 1704 create_aux_memory_mapper("Block Offset Table", 1705 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1706 G1BlockOffsetTable::heap_map_factor()); 1707 1708 G1RegionToSpaceMapper* cardtable_storage = 1709 create_aux_memory_mapper("Card Table", 1710 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1711 G1CardTable::heap_map_factor()); 1712 1713 G1RegionToSpaceMapper* card_counts_storage = 1714 create_aux_memory_mapper("Card Counts Table", 1715 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1716 G1CardCounts::heap_map_factor()); 1717 1718 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1719 G1RegionToSpaceMapper* prev_bitmap_storage = 1720 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1721 G1RegionToSpaceMapper* next_bitmap_storage = 1722 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1723 1724 _hrm = HeapRegionManager::create_manager(this); 1725 1726 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1727 _card_table->initialize(cardtable_storage); 1728 1729 // Do later initialization work for concurrent refinement. 1730 _hot_card_cache->initialize(card_counts_storage); 1731 1732 // 6843694 - ensure that the maximum region index can fit 1733 // in the remembered set structures. 1734 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1735 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1736 1737 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1738 // start within the first card. 1739 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1740 // Also create a G1 rem set. 1741 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1742 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1743 1744 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1745 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1746 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1747 "too many cards per region"); 1748 1749 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1750 1751 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1752 1753 { 1754 HeapWord* start = _hrm->reserved().start(); 1755 HeapWord* end = _hrm->reserved().end(); 1756 size_t granularity = HeapRegion::GrainBytes; 1757 1758 _region_attr.initialize(start, end, granularity); 1759 _humongous_reclaim_candidates.initialize(start, end, granularity); 1760 } 1761 1762 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1763 true /* are_GC_task_threads */, 1764 false /* are_ConcurrentGC_threads */); 1765 if (_workers == NULL) { 1766 return JNI_ENOMEM; 1767 } 1768 _workers->initialize_workers(); 1769 1770 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1771 1772 // Create the G1ConcurrentMark data structure and thread. 1773 // (Must do this late, so that "max_regions" is defined.) 1774 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1775 _cm_thread = _cm->cm_thread(); 1776 1777 // Now expand into the initial heap size. 1778 if (!expand(init_byte_size, _workers)) { 1779 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1780 return JNI_ENOMEM; 1781 } 1782 1783 // Perform any initialization actions delegated to the policy. 1784 policy()->init(this, &_collection_set); 1785 1786 jint ecode = initialize_concurrent_refinement(); 1787 if (ecode != JNI_OK) { 1788 return ecode; 1789 } 1790 1791 ecode = initialize_young_gen_sampling_thread(); 1792 if (ecode != JNI_OK) { 1793 return ecode; 1794 } 1795 1796 { 1797 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1798 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1799 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1800 } 1801 1802 // Here we allocate the dummy HeapRegion that is required by the 1803 // G1AllocRegion class. 1804 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1805 1806 // We'll re-use the same region whether the alloc region will 1807 // require BOT updates or not and, if it doesn't, then a non-young 1808 // region will complain that it cannot support allocations without 1809 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1810 dummy_region->set_eden(); 1811 // Make sure it's full. 1812 dummy_region->set_top(dummy_region->end()); 1813 G1AllocRegion::setup(this, dummy_region); 1814 1815 _allocator->init_mutator_alloc_regions(); 1816 1817 // Do create of the monitoring and management support so that 1818 // values in the heap have been properly initialized. 1819 _g1mm = new G1MonitoringSupport(this); 1820 1821 G1StringDedup::initialize(); 1822 1823 _preserved_marks_set.init(ParallelGCThreads); 1824 1825 _collection_set.initialize(max_regions()); 1826 1827 return JNI_OK; 1828 } 1829 1830 void G1CollectedHeap::stop() { 1831 // Stop all concurrent threads. We do this to make sure these threads 1832 // do not continue to execute and access resources (e.g. logging) 1833 // that are destroyed during shutdown. 1834 _cr->stop(); 1835 _young_gen_sampling_thread->stop(); 1836 _cm_thread->stop(); 1837 if (G1StringDedup::is_enabled()) { 1838 G1StringDedup::stop(); 1839 } 1840 } 1841 1842 void G1CollectedHeap::safepoint_synchronize_begin() { 1843 SuspendibleThreadSet::synchronize(); 1844 } 1845 1846 void G1CollectedHeap::safepoint_synchronize_end() { 1847 SuspendibleThreadSet::desynchronize(); 1848 } 1849 1850 void G1CollectedHeap::post_initialize() { 1851 CollectedHeap::post_initialize(); 1852 ref_processing_init(); 1853 } 1854 1855 void G1CollectedHeap::ref_processing_init() { 1856 // Reference processing in G1 currently works as follows: 1857 // 1858 // * There are two reference processor instances. One is 1859 // used to record and process discovered references 1860 // during concurrent marking; the other is used to 1861 // record and process references during STW pauses 1862 // (both full and incremental). 1863 // * Both ref processors need to 'span' the entire heap as 1864 // the regions in the collection set may be dotted around. 1865 // 1866 // * For the concurrent marking ref processor: 1867 // * Reference discovery is enabled at initial marking. 1868 // * Reference discovery is disabled and the discovered 1869 // references processed etc during remarking. 1870 // * Reference discovery is MT (see below). 1871 // * Reference discovery requires a barrier (see below). 1872 // * Reference processing may or may not be MT 1873 // (depending on the value of ParallelRefProcEnabled 1874 // and ParallelGCThreads). 1875 // * A full GC disables reference discovery by the CM 1876 // ref processor and abandons any entries on it's 1877 // discovered lists. 1878 // 1879 // * For the STW processor: 1880 // * Non MT discovery is enabled at the start of a full GC. 1881 // * Processing and enqueueing during a full GC is non-MT. 1882 // * During a full GC, references are processed after marking. 1883 // 1884 // * Discovery (may or may not be MT) is enabled at the start 1885 // of an incremental evacuation pause. 1886 // * References are processed near the end of a STW evacuation pause. 1887 // * For both types of GC: 1888 // * Discovery is atomic - i.e. not concurrent. 1889 // * Reference discovery will not need a barrier. 1890 1891 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1892 1893 // Concurrent Mark ref processor 1894 _ref_processor_cm = 1895 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1896 mt_processing, // mt processing 1897 ParallelGCThreads, // degree of mt processing 1898 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1899 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1900 false, // Reference discovery is not atomic 1901 &_is_alive_closure_cm, // is alive closure 1902 true); // allow changes to number of processing threads 1903 1904 // STW ref processor 1905 _ref_processor_stw = 1906 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1907 mt_processing, // mt processing 1908 ParallelGCThreads, // degree of mt processing 1909 (ParallelGCThreads > 1), // mt discovery 1910 ParallelGCThreads, // degree of mt discovery 1911 true, // Reference discovery is atomic 1912 &_is_alive_closure_stw, // is alive closure 1913 true); // allow changes to number of processing threads 1914 } 1915 1916 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1917 return &_soft_ref_policy; 1918 } 1919 1920 size_t G1CollectedHeap::capacity() const { 1921 return _hrm->length() * HeapRegion::GrainBytes; 1922 } 1923 1924 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1925 return _hrm->total_free_bytes(); 1926 } 1927 1928 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1929 _hot_card_cache->drain(cl, worker_id); 1930 } 1931 1932 // Computes the sum of the storage used by the various regions. 1933 size_t G1CollectedHeap::used() const { 1934 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1935 if (_archive_allocator != NULL) { 1936 result += _archive_allocator->used(); 1937 } 1938 return result; 1939 } 1940 1941 size_t G1CollectedHeap::used_unlocked() const { 1942 return _summary_bytes_used; 1943 } 1944 1945 class SumUsedClosure: public HeapRegionClosure { 1946 size_t _used; 1947 public: 1948 SumUsedClosure() : _used(0) {} 1949 bool do_heap_region(HeapRegion* r) { 1950 _used += r->used(); 1951 return false; 1952 } 1953 size_t result() { return _used; } 1954 }; 1955 1956 size_t G1CollectedHeap::recalculate_used() const { 1957 SumUsedClosure blk; 1958 heap_region_iterate(&blk); 1959 return blk.result(); 1960 } 1961 1962 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1963 switch (cause) { 1964 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1965 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1966 case GCCause::_wb_conc_mark: return true; 1967 default : return false; 1968 } 1969 } 1970 1971 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1972 switch (cause) { 1973 case GCCause::_g1_humongous_allocation: return true; 1974 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1975 case GCCause::_wb_breakpoint: return true; 1976 default: return is_user_requested_concurrent_full_gc(cause); 1977 } 1978 } 1979 1980 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 1981 if (policy()->force_upgrade_to_full()) { 1982 return true; 1983 } else if (should_do_concurrent_full_gc(_gc_cause)) { 1984 return false; 1985 } else if (has_regions_left_for_allocation()) { 1986 return false; 1987 } else { 1988 return true; 1989 } 1990 } 1991 1992 #ifndef PRODUCT 1993 void G1CollectedHeap::allocate_dummy_regions() { 1994 // Let's fill up most of the region 1995 size_t word_size = HeapRegion::GrainWords - 1024; 1996 // And as a result the region we'll allocate will be humongous. 1997 guarantee(is_humongous(word_size), "sanity"); 1998 1999 // _filler_array_max_size is set to humongous object threshold 2000 // but temporarily change it to use CollectedHeap::fill_with_object(). 2001 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2002 2003 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2004 // Let's use the existing mechanism for the allocation 2005 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2006 if (dummy_obj != NULL) { 2007 MemRegion mr(dummy_obj, word_size); 2008 CollectedHeap::fill_with_object(mr); 2009 } else { 2010 // If we can't allocate once, we probably cannot allocate 2011 // again. Let's get out of the loop. 2012 break; 2013 } 2014 } 2015 } 2016 #endif // !PRODUCT 2017 2018 void G1CollectedHeap::increment_old_marking_cycles_started() { 2019 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2020 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2021 "Wrong marking cycle count (started: %d, completed: %d)", 2022 _old_marking_cycles_started, _old_marking_cycles_completed); 2023 2024 _old_marking_cycles_started++; 2025 } 2026 2027 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2028 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 2029 2030 // We assume that if concurrent == true, then the caller is a 2031 // concurrent thread that was joined the Suspendible Thread 2032 // Set. If there's ever a cheap way to check this, we should add an 2033 // assert here. 2034 2035 // Given that this method is called at the end of a Full GC or of a 2036 // concurrent cycle, and those can be nested (i.e., a Full GC can 2037 // interrupt a concurrent cycle), the number of full collections 2038 // completed should be either one (in the case where there was no 2039 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2040 // behind the number of full collections started. 2041 2042 // This is the case for the inner caller, i.e. a Full GC. 2043 assert(concurrent || 2044 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2045 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2046 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2047 "is inconsistent with _old_marking_cycles_completed = %u", 2048 _old_marking_cycles_started, _old_marking_cycles_completed); 2049 2050 // This is the case for the outer caller, i.e. the concurrent cycle. 2051 assert(!concurrent || 2052 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2053 "for outer caller (concurrent cycle): " 2054 "_old_marking_cycles_started = %u " 2055 "is inconsistent with _old_marking_cycles_completed = %u", 2056 _old_marking_cycles_started, _old_marking_cycles_completed); 2057 2058 _old_marking_cycles_completed += 1; 2059 2060 // We need to clear the "in_progress" flag in the CM thread before 2061 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2062 // is set) so that if a waiter requests another System.gc() it doesn't 2063 // incorrectly see that a marking cycle is still in progress. 2064 if (concurrent) { 2065 _cm_thread->set_idle(); 2066 } 2067 2068 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 2069 // for a full GC to finish that their wait is over. 2070 ml.notify_all(); 2071 } 2072 2073 void G1CollectedHeap::collect(GCCause::Cause cause) { 2074 try_collect(cause); 2075 } 2076 2077 // Return true if (x < y) with allowance for wraparound. 2078 static bool gc_counter_less_than(uint x, uint y) { 2079 return (x - y) > (UINT_MAX/2); 2080 } 2081 2082 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 2083 // Macro so msg printing is format-checked. 2084 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 2085 do { \ 2086 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 2087 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 2088 ResourceMark rm; /* For thread name. */ \ 2089 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 2090 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 2091 Thread::current()->name(), \ 2092 GCCause::to_string(cause)); \ 2093 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 2094 } \ 2095 } while (0) 2096 2097 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 2098 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 2099 2100 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 2101 uint gc_counter, 2102 uint old_marking_started_before) { 2103 assert_heap_not_locked(); 2104 assert(should_do_concurrent_full_gc(cause), 2105 "Non-concurrent cause %s", GCCause::to_string(cause)); 2106 2107 for (uint i = 1; true; ++i) { 2108 // Try to schedule an initial-mark evacuation pause that will 2109 // start a concurrent cycle. 2110 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 2111 VM_G1TryInitiateConcMark op(gc_counter, 2112 cause, 2113 policy()->max_pause_time_ms()); 2114 VMThread::execute(&op); 2115 2116 // Request is trivially finished. 2117 if (cause == GCCause::_g1_periodic_collection) { 2118 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 2119 return op.gc_succeeded(); 2120 } 2121 2122 // If VMOp skipped initiating concurrent marking cycle because 2123 // we're terminating, then we're done. 2124 if (op.terminating()) { 2125 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 2126 return false; 2127 } 2128 2129 // Lock to get consistent set of values. 2130 uint old_marking_started_after; 2131 uint old_marking_completed_after; 2132 { 2133 MutexLocker ml(Heap_lock); 2134 // Update gc_counter for retrying VMOp if needed. Captured here to be 2135 // consistent with the values we use below for termination tests. If 2136 // a retry is needed after a possible wait, and another collection 2137 // occurs in the meantime, it will cause our retry to be skipped and 2138 // we'll recheck for termination with updated conditions from that 2139 // more recent collection. That's what we want, rather than having 2140 // our retry possibly perform an unnecessary collection. 2141 gc_counter = total_collections(); 2142 old_marking_started_after = _old_marking_cycles_started; 2143 old_marking_completed_after = _old_marking_cycles_completed; 2144 } 2145 2146 if (cause == GCCause::_wb_breakpoint) { 2147 if (op.gc_succeeded()) { 2148 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2149 return true; 2150 } 2151 // When _wb_breakpoint there can't be another cycle or deferred. 2152 assert(!op.cycle_already_in_progress(), "invariant"); 2153 assert(!op.whitebox_attached(), "invariant"); 2154 // Concurrent cycle attempt might have been cancelled by some other 2155 // collection, so retry. Unlike other cases below, we want to retry 2156 // even if cancelled by a STW full collection, because we really want 2157 // to start a concurrent cycle. 2158 if (old_marking_started_before != old_marking_started_after) { 2159 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 2160 old_marking_started_before = old_marking_started_after; 2161 } 2162 } else if (!GCCause::is_user_requested_gc(cause)) { 2163 // For an "automatic" (not user-requested) collection, we just need to 2164 // ensure that progress is made. 2165 // 2166 // Request is finished if any of 2167 // (1) the VMOp successfully performed a GC, 2168 // (2) a concurrent cycle was already in progress, 2169 // (3) whitebox is controlling concurrent cycles, 2170 // (4) a new cycle was started (by this thread or some other), or 2171 // (5) a Full GC was performed. 2172 // Cases (4) and (5) are detected together by a change to 2173 // _old_marking_cycles_started. 2174 // 2175 // Note that (1) does not imply (4). If we're still in the mixed 2176 // phase of an earlier concurrent collection, the request to make the 2177 // collection an initial-mark won't be honored. If we don't check for 2178 // both conditions we'll spin doing back-to-back collections. 2179 if (op.gc_succeeded() || 2180 op.cycle_already_in_progress() || 2181 op.whitebox_attached() || 2182 (old_marking_started_before != old_marking_started_after)) { 2183 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2184 return true; 2185 } 2186 } else { // User-requested GC. 2187 // For a user-requested collection, we want to ensure that a complete 2188 // full collection has been performed before returning, but without 2189 // waiting for more than needed. 2190 2191 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 2192 // new cycle was started. That's good, because it's not clear what we 2193 // should do otherwise. Trying again just does back to back GCs. 2194 // Can't wait for someone else to start a cycle. And returning fails 2195 // to meet the goal of ensuring a full collection was performed. 2196 assert(!op.gc_succeeded() || 2197 (old_marking_started_before != old_marking_started_after), 2198 "invariant: succeeded %s, started before %u, started after %u", 2199 BOOL_TO_STR(op.gc_succeeded()), 2200 old_marking_started_before, old_marking_started_after); 2201 2202 // Request is finished if a full collection (concurrent or stw) 2203 // was started after this request and has completed, e.g. 2204 // started_before < completed_after. 2205 if (gc_counter_less_than(old_marking_started_before, 2206 old_marking_completed_after)) { 2207 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2208 return true; 2209 } 2210 2211 if (old_marking_started_after != old_marking_completed_after) { 2212 // If there is an in-progress cycle (possibly started by us), then 2213 // wait for that cycle to complete, e.g. 2214 // while completed_now < started_after. 2215 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2216 MonitorLocker ml(G1OldGCCount_lock); 2217 while (gc_counter_less_than(_old_marking_cycles_completed, 2218 old_marking_started_after)) { 2219 ml.wait(); 2220 } 2221 // Request is finished if the collection we just waited for was 2222 // started after this request. 2223 if (old_marking_started_before != old_marking_started_after) { 2224 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2225 return true; 2226 } 2227 } 2228 2229 // If VMOp was successful then it started a new cycle that the above 2230 // wait &etc should have recognized as finishing this request. This 2231 // differs from a non-user-request, where gc_succeeded does not imply 2232 // a new cycle was started. 2233 assert(!op.gc_succeeded(), "invariant"); 2234 2235 if (op.cycle_already_in_progress()) { 2236 // If VMOp failed because a cycle was already in progress, it 2237 // is now complete. But it didn't finish this user-requested 2238 // GC, so try again. 2239 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2240 continue; 2241 } else if (op.whitebox_attached()) { 2242 // If WhiteBox wants control, wait for notification of a state 2243 // change in the controller, then try again. Don't wait for 2244 // release of control, since collections may complete while in 2245 // control. Note: This won't recognize a STW full collection 2246 // while waiting; we can't wait on multiple monitors. 2247 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 2248 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 2249 if (ConcurrentGCBreakpoints::is_controlled()) { 2250 ml.wait(); 2251 } 2252 continue; 2253 } 2254 } 2255 2256 // Collection failed and should be retried. 2257 assert(op.transient_failure(), "invariant"); 2258 2259 if (GCLocker::is_active_and_needs_gc()) { 2260 // If GCLocker is active, wait until clear before retrying. 2261 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2262 GCLocker::stall_until_clear(); 2263 } 2264 2265 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2266 } 2267 } 2268 2269 bool G1CollectedHeap::try_collect(GCCause::Cause cause) { 2270 assert_heap_not_locked(); 2271 2272 // Lock to get consistent set of values. 2273 uint gc_count_before; 2274 uint full_gc_count_before; 2275 uint old_marking_started_before; 2276 { 2277 MutexLocker ml(Heap_lock); 2278 gc_count_before = total_collections(); 2279 full_gc_count_before = total_full_collections(); 2280 old_marking_started_before = _old_marking_cycles_started; 2281 } 2282 2283 if (should_do_concurrent_full_gc(cause)) { 2284 return try_collect_concurrently(cause, 2285 gc_count_before, 2286 old_marking_started_before); 2287 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2288 // Indicate failure to be consistent with VMOp failure due to 2289 // another collection slipping in after our gc_count but before 2290 // our request is processed. 2291 return false; 2292 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2293 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2294 2295 // Schedule a standard evacuation pause. We're setting word_size 2296 // to 0 which means that we are not requesting a post-GC allocation. 2297 VM_G1CollectForAllocation op(0, /* word_size */ 2298 gc_count_before, 2299 cause, 2300 policy()->max_pause_time_ms()); 2301 VMThread::execute(&op); 2302 return op.gc_succeeded(); 2303 } else { 2304 // Schedule a Full GC. 2305 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2306 VMThread::execute(&op); 2307 return op.gc_succeeded(); 2308 } 2309 } 2310 2311 bool G1CollectedHeap::is_in(const void* p) const { 2312 if (_hrm->reserved().contains(p)) { 2313 // Given that we know that p is in the reserved space, 2314 // heap_region_containing() should successfully 2315 // return the containing region. 2316 HeapRegion* hr = heap_region_containing(p); 2317 return hr->is_in(p); 2318 } else { 2319 return false; 2320 } 2321 } 2322 2323 #ifdef ASSERT 2324 bool G1CollectedHeap::is_in_exact(const void* p) const { 2325 bool contains = reserved_region().contains(p); 2326 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2327 if (contains && available) { 2328 return true; 2329 } else { 2330 return false; 2331 } 2332 } 2333 #endif 2334 2335 // Iteration functions. 2336 2337 // Iterates an ObjectClosure over all objects within a HeapRegion. 2338 2339 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2340 ObjectClosure* _cl; 2341 public: 2342 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2343 bool do_heap_region(HeapRegion* r) { 2344 if (!r->is_continues_humongous()) { 2345 r->object_iterate(_cl); 2346 } 2347 return false; 2348 } 2349 }; 2350 2351 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2352 IterateObjectClosureRegionClosure blk(cl); 2353 heap_region_iterate(&blk); 2354 } 2355 2356 void G1CollectedHeap::keep_alive(oop obj) { 2357 G1BarrierSet::enqueue(obj); 2358 } 2359 2360 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2361 _hrm->iterate(cl); 2362 } 2363 2364 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2365 HeapRegionClaimer *hrclaimer, 2366 uint worker_id) const { 2367 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2368 } 2369 2370 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2371 HeapRegionClaimer *hrclaimer) const { 2372 _hrm->par_iterate(cl, hrclaimer, 0); 2373 } 2374 2375 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2376 _collection_set.iterate(cl); 2377 } 2378 2379 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2380 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers()); 2381 } 2382 2383 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2384 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2385 } 2386 2387 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2388 HeapRegion* hr = heap_region_containing(addr); 2389 return hr->block_start(addr); 2390 } 2391 2392 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2393 HeapRegion* hr = heap_region_containing(addr); 2394 return hr->block_is_obj(addr); 2395 } 2396 2397 bool G1CollectedHeap::supports_tlab_allocation() const { 2398 return true; 2399 } 2400 2401 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2402 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2403 } 2404 2405 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2406 return _eden.length() * HeapRegion::GrainBytes; 2407 } 2408 2409 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2410 // must be equal to the humongous object limit. 2411 size_t G1CollectedHeap::max_tlab_size() const { 2412 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2413 } 2414 2415 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2416 return _allocator->unsafe_max_tlab_alloc(); 2417 } 2418 2419 size_t G1CollectedHeap::max_capacity() const { 2420 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2421 } 2422 2423 size_t G1CollectedHeap::max_reserved_capacity() const { 2424 return _hrm->max_length() * HeapRegion::GrainBytes; 2425 } 2426 2427 jlong G1CollectedHeap::millis_since_last_gc() { 2428 // See the notes in GenCollectedHeap::millis_since_last_gc() 2429 // for more information about the implementation. 2430 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2431 _policy->collection_pause_end_millis(); 2432 if (ret_val < 0) { 2433 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2434 ". returning zero instead.", ret_val); 2435 return 0; 2436 } 2437 return ret_val; 2438 } 2439 2440 void G1CollectedHeap::deduplicate_string(oop str) { 2441 assert(java_lang_String::is_instance(str), "invariant"); 2442 2443 if (G1StringDedup::is_enabled()) { 2444 G1StringDedup::deduplicate(str); 2445 } 2446 } 2447 2448 void G1CollectedHeap::prepare_for_verify() { 2449 _verifier->prepare_for_verify(); 2450 } 2451 2452 void G1CollectedHeap::verify(VerifyOption vo) { 2453 _verifier->verify(vo); 2454 } 2455 2456 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2457 return true; 2458 } 2459 2460 bool G1CollectedHeap::is_heterogeneous_heap() const { 2461 return G1Arguments::is_heterogeneous_heap(); 2462 } 2463 2464 class PrintRegionClosure: public HeapRegionClosure { 2465 outputStream* _st; 2466 public: 2467 PrintRegionClosure(outputStream* st) : _st(st) {} 2468 bool do_heap_region(HeapRegion* r) { 2469 r->print_on(_st); 2470 return false; 2471 } 2472 }; 2473 2474 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2475 const HeapRegion* hr, 2476 const VerifyOption vo) const { 2477 switch (vo) { 2478 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2479 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2480 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2481 default: ShouldNotReachHere(); 2482 } 2483 return false; // keep some compilers happy 2484 } 2485 2486 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2487 const VerifyOption vo) const { 2488 switch (vo) { 2489 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2490 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2491 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2492 default: ShouldNotReachHere(); 2493 } 2494 return false; // keep some compilers happy 2495 } 2496 2497 void G1CollectedHeap::print_heap_regions() const { 2498 LogTarget(Trace, gc, heap, region) lt; 2499 if (lt.is_enabled()) { 2500 LogStream ls(lt); 2501 print_regions_on(&ls); 2502 } 2503 } 2504 2505 void G1CollectedHeap::print_on(outputStream* st) const { 2506 st->print(" %-20s", "garbage-first heap"); 2507 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2508 capacity()/K, used_unlocked()/K); 2509 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2510 p2i(_hrm->reserved().start()), 2511 p2i(_hrm->reserved().end())); 2512 st->cr(); 2513 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2514 uint young_regions = young_regions_count(); 2515 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2516 (size_t) young_regions * HeapRegion::GrainBytes / K); 2517 uint survivor_regions = survivor_regions_count(); 2518 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2519 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2520 st->cr(); 2521 if (_numa->is_enabled()) { 2522 uint num_nodes = _numa->num_active_nodes(); 2523 st->print(" remaining free region(s) on each NUMA node: "); 2524 const int* node_ids = _numa->node_ids(); 2525 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2526 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index)); 2527 } 2528 st->cr(); 2529 } 2530 MetaspaceUtils::print_on(st); 2531 } 2532 2533 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2534 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2535 "HS=humongous(starts), HC=humongous(continues), " 2536 "CS=collection set, F=free, " 2537 "OA=open archive, CA=closed archive, " 2538 "TAMS=top-at-mark-start (previous, next)"); 2539 PrintRegionClosure blk(st); 2540 heap_region_iterate(&blk); 2541 } 2542 2543 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2544 print_on(st); 2545 2546 // Print the per-region information. 2547 print_regions_on(st); 2548 } 2549 2550 void G1CollectedHeap::print_on_error(outputStream* st) const { 2551 this->CollectedHeap::print_on_error(st); 2552 2553 if (_cm != NULL) { 2554 st->cr(); 2555 _cm->print_on_error(st); 2556 } 2557 } 2558 2559 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2560 workers()->print_worker_threads_on(st); 2561 _cm_thread->print_on(st); 2562 st->cr(); 2563 _cm->print_worker_threads_on(st); 2564 _cr->print_threads_on(st); 2565 _young_gen_sampling_thread->print_on(st); 2566 if (G1StringDedup::is_enabled()) { 2567 G1StringDedup::print_worker_threads_on(st); 2568 } 2569 } 2570 2571 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2572 workers()->threads_do(tc); 2573 tc->do_thread(_cm_thread); 2574 _cm->threads_do(tc); 2575 _cr->threads_do(tc); 2576 tc->do_thread(_young_gen_sampling_thread); 2577 if (G1StringDedup::is_enabled()) { 2578 G1StringDedup::threads_do(tc); 2579 } 2580 } 2581 2582 void G1CollectedHeap::print_tracing_info() const { 2583 rem_set()->print_summary_info(); 2584 concurrent_mark()->print_summary_info(); 2585 } 2586 2587 #ifndef PRODUCT 2588 // Helpful for debugging RSet issues. 2589 2590 class PrintRSetsClosure : public HeapRegionClosure { 2591 private: 2592 const char* _msg; 2593 size_t _occupied_sum; 2594 2595 public: 2596 bool do_heap_region(HeapRegion* r) { 2597 HeapRegionRemSet* hrrs = r->rem_set(); 2598 size_t occupied = hrrs->occupied(); 2599 _occupied_sum += occupied; 2600 2601 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2602 if (occupied == 0) { 2603 tty->print_cr(" RSet is empty"); 2604 } else { 2605 hrrs->print(); 2606 } 2607 tty->print_cr("----------"); 2608 return false; 2609 } 2610 2611 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2612 tty->cr(); 2613 tty->print_cr("========================================"); 2614 tty->print_cr("%s", msg); 2615 tty->cr(); 2616 } 2617 2618 ~PrintRSetsClosure() { 2619 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2620 tty->print_cr("========================================"); 2621 tty->cr(); 2622 } 2623 }; 2624 2625 void G1CollectedHeap::print_cset_rsets() { 2626 PrintRSetsClosure cl("Printing CSet RSets"); 2627 collection_set_iterate_all(&cl); 2628 } 2629 2630 void G1CollectedHeap::print_all_rsets() { 2631 PrintRSetsClosure cl("Printing All RSets");; 2632 heap_region_iterate(&cl); 2633 } 2634 #endif // PRODUCT 2635 2636 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2637 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2638 } 2639 2640 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2641 2642 size_t eden_used_bytes = _eden.used_bytes(); 2643 size_t survivor_used_bytes = _survivor.used_bytes(); 2644 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2645 2646 size_t eden_capacity_bytes = 2647 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2648 2649 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2650 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2651 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2652 } 2653 2654 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2655 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2656 stats->unused(), stats->used(), stats->region_end_waste(), 2657 stats->regions_filled(), stats->direct_allocated(), 2658 stats->failure_used(), stats->failure_waste()); 2659 } 2660 2661 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2662 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2663 gc_tracer->report_gc_heap_summary(when, heap_summary); 2664 2665 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2666 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2667 } 2668 2669 G1CollectedHeap* G1CollectedHeap::heap() { 2670 CollectedHeap* heap = Universe::heap(); 2671 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2672 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2673 return (G1CollectedHeap*)heap; 2674 } 2675 2676 void G1CollectedHeap::gc_prologue(bool full) { 2677 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2678 2679 // This summary needs to be printed before incrementing total collections. 2680 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2681 2682 // Update common counters. 2683 increment_total_collections(full /* full gc */); 2684 if (full || collector_state()->in_initial_mark_gc()) { 2685 increment_old_marking_cycles_started(); 2686 } 2687 2688 // Fill TLAB's and such 2689 { 2690 Ticks start = Ticks::now(); 2691 ensure_parsability(true); 2692 Tickspan dt = Ticks::now() - start; 2693 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS); 2694 } 2695 2696 if (!full) { 2697 // Flush dirty card queues to qset, so later phases don't need to account 2698 // for partially filled per-thread queues and such. Not needed for full 2699 // collections, which ignore those logs. 2700 Ticks start = Ticks::now(); 2701 G1BarrierSet::dirty_card_queue_set().concatenate_logs(); 2702 Tickspan dt = Ticks::now() - start; 2703 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS); 2704 } 2705 } 2706 2707 void G1CollectedHeap::gc_epilogue(bool full) { 2708 // Update common counters. 2709 if (full) { 2710 // Update the number of full collections that have been completed. 2711 increment_old_marking_cycles_completed(false /* concurrent */); 2712 } 2713 2714 // We are at the end of the GC. Total collections has already been increased. 2715 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2716 2717 // FIXME: what is this about? 2718 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2719 // is set. 2720 #if COMPILER2_OR_JVMCI 2721 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2722 #endif 2723 2724 double start = os::elapsedTime(); 2725 resize_all_tlabs(); 2726 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2727 2728 MemoryService::track_memory_usage(); 2729 // We have just completed a GC. Update the soft reference 2730 // policy with the new heap occupancy 2731 Universe::update_heap_info_at_gc(); 2732 2733 // Print NUMA statistics. 2734 _numa->print_statistics(); 2735 } 2736 2737 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2738 LogTarget(Trace, gc, heap, verify) lt; 2739 2740 if (lt.is_enabled()) { 2741 LogStream ls(lt); 2742 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2743 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2744 heap_region_iterate(&cl); 2745 } 2746 } 2747 2748 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2749 uint gc_count_before, 2750 bool* succeeded, 2751 GCCause::Cause gc_cause) { 2752 assert_heap_not_locked_and_not_at_safepoint(); 2753 VM_G1CollectForAllocation op(word_size, 2754 gc_count_before, 2755 gc_cause, 2756 policy()->max_pause_time_ms()); 2757 VMThread::execute(&op); 2758 2759 HeapWord* result = op.result(); 2760 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2761 assert(result == NULL || ret_succeeded, 2762 "the result should be NULL if the VM did not succeed"); 2763 *succeeded = ret_succeeded; 2764 2765 assert_heap_not_locked(); 2766 return result; 2767 } 2768 2769 void G1CollectedHeap::do_concurrent_mark() { 2770 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2771 if (!_cm_thread->in_progress()) { 2772 _cm_thread->set_started(); 2773 CGC_lock->notify(); 2774 } 2775 } 2776 2777 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2778 // We don't nominate objects with many remembered set entries, on 2779 // the assumption that such objects are likely still live. 2780 HeapRegionRemSet* rem_set = r->rem_set(); 2781 2782 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2783 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2784 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2785 } 2786 2787 #ifndef PRODUCT 2788 void G1CollectedHeap::verify_region_attr_remset_update() { 2789 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2790 public: 2791 virtual bool do_heap_region(HeapRegion* r) { 2792 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2793 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2794 assert(r->rem_set()->is_tracked() == needs_remset_update, 2795 "Region %u remset tracking status (%s) different to region attribute (%s)", 2796 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2797 return false; 2798 } 2799 } cl; 2800 heap_region_iterate(&cl); 2801 } 2802 #endif 2803 2804 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2805 public: 2806 bool do_heap_region(HeapRegion* hr) { 2807 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2808 hr->verify_rem_set(); 2809 } 2810 return false; 2811 } 2812 }; 2813 2814 uint G1CollectedHeap::num_task_queues() const { 2815 return _task_queues->size(); 2816 } 2817 2818 #if TASKQUEUE_STATS 2819 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2820 st->print_raw_cr("GC Task Stats"); 2821 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2822 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2823 } 2824 2825 void G1CollectedHeap::print_taskqueue_stats() const { 2826 if (!log_is_enabled(Trace, gc, task, stats)) { 2827 return; 2828 } 2829 Log(gc, task, stats) log; 2830 ResourceMark rm; 2831 LogStream ls(log.trace()); 2832 outputStream* st = &ls; 2833 2834 print_taskqueue_stats_hdr(st); 2835 2836 TaskQueueStats totals; 2837 const uint n = num_task_queues(); 2838 for (uint i = 0; i < n; ++i) { 2839 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2840 totals += task_queue(i)->stats; 2841 } 2842 st->print_raw("tot "); totals.print(st); st->cr(); 2843 2844 DEBUG_ONLY(totals.verify()); 2845 } 2846 2847 void G1CollectedHeap::reset_taskqueue_stats() { 2848 const uint n = num_task_queues(); 2849 for (uint i = 0; i < n; ++i) { 2850 task_queue(i)->stats.reset(); 2851 } 2852 } 2853 #endif // TASKQUEUE_STATS 2854 2855 void G1CollectedHeap::wait_for_root_region_scanning() { 2856 double scan_wait_start = os::elapsedTime(); 2857 // We have to wait until the CM threads finish scanning the 2858 // root regions as it's the only way to ensure that all the 2859 // objects on them have been correctly scanned before we start 2860 // moving them during the GC. 2861 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2862 double wait_time_ms = 0.0; 2863 if (waited) { 2864 double scan_wait_end = os::elapsedTime(); 2865 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2866 } 2867 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2868 } 2869 2870 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2871 private: 2872 G1HRPrinter* _hr_printer; 2873 public: 2874 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2875 2876 virtual bool do_heap_region(HeapRegion* r) { 2877 _hr_printer->cset(r); 2878 return false; 2879 } 2880 }; 2881 2882 void G1CollectedHeap::start_new_collection_set() { 2883 double start = os::elapsedTime(); 2884 2885 collection_set()->start_incremental_building(); 2886 2887 clear_region_attr(); 2888 2889 guarantee(_eden.length() == 0, "eden should have been cleared"); 2890 policy()->transfer_survivors_to_cset(survivor()); 2891 2892 // We redo the verification but now wrt to the new CSet which 2893 // has just got initialized after the previous CSet was freed. 2894 _cm->verify_no_collection_set_oops(); 2895 2896 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2897 } 2898 2899 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2900 2901 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2902 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2903 collection_set()->optional_region_length()); 2904 2905 _cm->verify_no_collection_set_oops(); 2906 2907 if (_hr_printer.is_active()) { 2908 G1PrintCollectionSetClosure cl(&_hr_printer); 2909 _collection_set.iterate(&cl); 2910 _collection_set.iterate_optional(&cl); 2911 } 2912 } 2913 2914 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2915 if (collector_state()->in_initial_mark_gc()) { 2916 return G1HeapVerifier::G1VerifyConcurrentStart; 2917 } else if (collector_state()->in_young_only_phase()) { 2918 return G1HeapVerifier::G1VerifyYoungNormal; 2919 } else { 2920 return G1HeapVerifier::G1VerifyMixed; 2921 } 2922 } 2923 2924 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2925 if (VerifyRememberedSets) { 2926 log_info(gc, verify)("[Verifying RemSets before GC]"); 2927 VerifyRegionRemSetClosure v_cl; 2928 heap_region_iterate(&v_cl); 2929 } 2930 _verifier->verify_before_gc(type); 2931 _verifier->check_bitmaps("GC Start"); 2932 verify_numa_regions("GC Start"); 2933 } 2934 2935 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2936 if (VerifyRememberedSets) { 2937 log_info(gc, verify)("[Verifying RemSets after GC]"); 2938 VerifyRegionRemSetClosure v_cl; 2939 heap_region_iterate(&v_cl); 2940 } 2941 _verifier->verify_after_gc(type); 2942 _verifier->check_bitmaps("GC End"); 2943 verify_numa_regions("GC End"); 2944 } 2945 2946 void G1CollectedHeap::expand_heap_after_young_collection(){ 2947 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2948 if (expand_bytes > 0) { 2949 // No need for an ergo logging here, 2950 // expansion_amount() does this when it returns a value > 0. 2951 double expand_ms; 2952 if (!expand(expand_bytes, _workers, &expand_ms)) { 2953 // We failed to expand the heap. Cannot do anything about it. 2954 } 2955 phase_times()->record_expand_heap_time(expand_ms); 2956 } 2957 } 2958 2959 const char* G1CollectedHeap::young_gc_name() const { 2960 if (collector_state()->in_initial_mark_gc()) { 2961 return "Pause Young (Concurrent Start)"; 2962 } else if (collector_state()->in_young_only_phase()) { 2963 if (collector_state()->in_young_gc_before_mixed()) { 2964 return "Pause Young (Prepare Mixed)"; 2965 } else { 2966 return "Pause Young (Normal)"; 2967 } 2968 } else { 2969 return "Pause Young (Mixed)"; 2970 } 2971 } 2972 2973 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2974 assert_at_safepoint_on_vm_thread(); 2975 guarantee(!is_gc_active(), "collection is not reentrant"); 2976 2977 if (GCLocker::check_active_before_gc()) { 2978 return false; 2979 } 2980 2981 do_collection_pause_at_safepoint_helper(target_pause_time_ms); 2982 if (should_upgrade_to_full_gc(gc_cause())) { 2983 log_info(gc, ergo)("Attempting maximally compacting collection"); 2984 bool result = do_full_collection(false /* explicit gc */, 2985 true /* clear_all_soft_refs */); 2986 // do_full_collection only fails if blocked by GC locker, but 2987 // we've already checked for that above. 2988 assert(result, "invariant"); 2989 } 2990 return true; 2991 } 2992 2993 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) { 2994 GCIdMark gc_id_mark; 2995 2996 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2997 ResourceMark rm; 2998 2999 policy()->note_gc_start(); 3000 3001 _gc_timer_stw->register_gc_start(); 3002 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3003 3004 wait_for_root_region_scanning(); 3005 3006 print_heap_before_gc(); 3007 print_heap_regions(); 3008 trace_heap_before_gc(_gc_tracer_stw); 3009 3010 _verifier->verify_region_sets_optional(); 3011 _verifier->verify_dirty_young_regions(); 3012 3013 // We should not be doing initial mark unless the conc mark thread is running 3014 if (!_cm_thread->should_terminate()) { 3015 // This call will decide whether this pause is an initial-mark 3016 // pause. If it is, in_initial_mark_gc() will return true 3017 // for the duration of this pause. 3018 policy()->decide_on_conc_mark_initiation(); 3019 } 3020 3021 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3022 assert(!collector_state()->in_initial_mark_gc() || 3023 collector_state()->in_young_only_phase(), "sanity"); 3024 // We also do not allow mixed GCs during marking. 3025 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 3026 3027 // Record whether this pause is an initial mark. When the current 3028 // thread has completed its logging output and it's safe to signal 3029 // the CM thread, the flag's value in the policy has been reset. 3030 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 3031 if (should_start_conc_mark) { 3032 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3033 } 3034 3035 // Inner scope for scope based logging, timers, and stats collection 3036 { 3037 G1EvacuationInfo evacuation_info; 3038 3039 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3040 3041 GCTraceCPUTime tcpu; 3042 3043 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3044 3045 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3046 workers()->active_workers(), 3047 Threads::number_of_non_daemon_threads()); 3048 active_workers = workers()->update_active_workers(active_workers); 3049 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3050 3051 G1MonitoringScope ms(g1mm(), 3052 false /* full_gc */, 3053 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3054 3055 G1HeapTransition heap_transition(this); 3056 3057 { 3058 IsGCActiveMark x; 3059 3060 gc_prologue(false); 3061 3062 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3063 verify_before_young_collection(verify_type); 3064 3065 { 3066 // The elapsed time induced by the start time below deliberately elides 3067 // the possible verification above. 3068 double sample_start_time_sec = os::elapsedTime(); 3069 3070 // Please see comment in g1CollectedHeap.hpp and 3071 // G1CollectedHeap::ref_processing_init() to see how 3072 // reference processing currently works in G1. 3073 _ref_processor_stw->enable_discovery(); 3074 3075 // We want to temporarily turn off discovery by the 3076 // CM ref processor, if necessary, and turn it back on 3077 // on again later if we do. Using a scoped 3078 // NoRefDiscovery object will do this. 3079 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3080 3081 policy()->record_collection_pause_start(sample_start_time_sec); 3082 3083 // Forget the current allocation region (we might even choose it to be part 3084 // of the collection set!). 3085 _allocator->release_mutator_alloc_regions(); 3086 3087 calculate_collection_set(evacuation_info, target_pause_time_ms); 3088 3089 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3090 G1ParScanThreadStateSet per_thread_states(this, 3091 &rdcqs, 3092 workers()->active_workers(), 3093 collection_set()->young_region_length(), 3094 collection_set()->optional_region_length()); 3095 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3096 3097 // Actually do the work... 3098 evacuate_initial_collection_set(&per_thread_states); 3099 3100 if (_collection_set.optional_region_length() != 0) { 3101 evacuate_optional_collection_set(&per_thread_states); 3102 } 3103 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3104 3105 start_new_collection_set(); 3106 3107 _survivor_evac_stats.adjust_desired_plab_sz(); 3108 _old_evac_stats.adjust_desired_plab_sz(); 3109 3110 if (should_start_conc_mark) { 3111 // We have to do this before we notify the CM threads that 3112 // they can start working to make sure that all the 3113 // appropriate initialization is done on the CM object. 3114 concurrent_mark()->post_initial_mark(); 3115 // Note that we don't actually trigger the CM thread at 3116 // this point. We do that later when we're sure that 3117 // the current thread has completed its logging output. 3118 } 3119 3120 allocate_dummy_regions(); 3121 3122 _allocator->init_mutator_alloc_regions(); 3123 3124 expand_heap_after_young_collection(); 3125 3126 double sample_end_time_sec = os::elapsedTime(); 3127 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3128 policy()->record_collection_pause_end(pause_time_ms); 3129 } 3130 3131 verify_after_young_collection(verify_type); 3132 3133 gc_epilogue(false); 3134 } 3135 3136 // Print the remainder of the GC log output. 3137 if (evacuation_failed()) { 3138 log_info(gc)("To-space exhausted"); 3139 } 3140 3141 policy()->print_phases(); 3142 heap_transition.print(); 3143 3144 _hrm->verify_optional(); 3145 _verifier->verify_region_sets_optional(); 3146 3147 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3148 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3149 3150 print_heap_after_gc(); 3151 print_heap_regions(); 3152 trace_heap_after_gc(_gc_tracer_stw); 3153 3154 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3155 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3156 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3157 // before any GC notifications are raised. 3158 g1mm()->update_sizes(); 3159 3160 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3161 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3162 _gc_timer_stw->register_gc_end(); 3163 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3164 } 3165 // It should now be safe to tell the concurrent mark thread to start 3166 // without its logging output interfering with the logging output 3167 // that came from the pause. 3168 3169 if (should_start_conc_mark) { 3170 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3171 // thread(s) could be running concurrently with us. Make sure that anything 3172 // after this point does not assume that we are the only GC thread running. 3173 // Note: of course, the actual marking work will not start until the safepoint 3174 // itself is released in SuspendibleThreadSet::desynchronize(). 3175 do_concurrent_mark(); 3176 ConcurrentGCBreakpoints::notify_idle_to_active(); 3177 } 3178 } 3179 3180 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3181 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3182 workers()->run_task(&rsfp_task); 3183 } 3184 3185 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3186 double remove_self_forwards_start = os::elapsedTime(); 3187 3188 remove_self_forwarding_pointers(rdcqs); 3189 _preserved_marks_set.restore(workers()); 3190 3191 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3192 } 3193 3194 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3195 if (!_evacuation_failed) { 3196 _evacuation_failed = true; 3197 } 3198 3199 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3200 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3201 } 3202 3203 bool G1ParEvacuateFollowersClosure::offer_termination() { 3204 EventGCPhaseParallel event; 3205 G1ParScanThreadState* const pss = par_scan_state(); 3206 start_term_time(); 3207 const bool res = terminator()->offer_termination(); 3208 end_term_time(); 3209 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3210 return res; 3211 } 3212 3213 void G1ParEvacuateFollowersClosure::do_void() { 3214 EventGCPhaseParallel event; 3215 G1ParScanThreadState* const pss = par_scan_state(); 3216 pss->trim_queue(); 3217 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3218 do { 3219 EventGCPhaseParallel event; 3220 pss->steal_and_trim_queue(queues()); 3221 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3222 } while (!offer_termination()); 3223 } 3224 3225 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3226 bool class_unloading_occurred) { 3227 uint num_workers = workers()->active_workers(); 3228 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3229 workers()->run_task(&unlink_task); 3230 } 3231 3232 // Clean string dedup data structures. 3233 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3234 // record the durations of the phases. Hence the almost-copy. 3235 class G1StringDedupCleaningTask : public AbstractGangTask { 3236 BoolObjectClosure* _is_alive; 3237 OopClosure* _keep_alive; 3238 G1GCPhaseTimes* _phase_times; 3239 3240 public: 3241 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3242 OopClosure* keep_alive, 3243 G1GCPhaseTimes* phase_times) : 3244 AbstractGangTask("Partial Cleaning Task"), 3245 _is_alive(is_alive), 3246 _keep_alive(keep_alive), 3247 _phase_times(phase_times) 3248 { 3249 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3250 StringDedup::gc_prologue(true); 3251 } 3252 3253 ~G1StringDedupCleaningTask() { 3254 StringDedup::gc_epilogue(); 3255 } 3256 3257 void work(uint worker_id) { 3258 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3259 { 3260 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3261 StringDedupQueue::unlink_or_oops_do(&cl); 3262 } 3263 { 3264 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3265 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3266 } 3267 } 3268 }; 3269 3270 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3271 OopClosure* keep_alive, 3272 G1GCPhaseTimes* phase_times) { 3273 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3274 workers()->run_task(&cl); 3275 } 3276 3277 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3278 private: 3279 G1RedirtyCardsQueueSet* _qset; 3280 G1CollectedHeap* _g1h; 3281 BufferNode* volatile _nodes; 3282 3283 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3284 size_t buffer_size = _qset->buffer_size(); 3285 BufferNode* next = Atomic::load(&_nodes); 3286 while (next != NULL) { 3287 BufferNode* node = next; 3288 next = Atomic::cmpxchg(&_nodes, node, node->next()); 3289 if (next == node) { 3290 cl->apply_to_buffer(node, buffer_size, worker_id); 3291 next = node->next(); 3292 } 3293 } 3294 } 3295 3296 public: 3297 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3298 AbstractGangTask("Redirty Cards"), 3299 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3300 3301 virtual void work(uint worker_id) { 3302 G1GCPhaseTimes* p = _g1h->phase_times(); 3303 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3304 3305 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3306 par_apply(&cl, worker_id); 3307 3308 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3309 } 3310 }; 3311 3312 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3313 double redirty_logged_cards_start = os::elapsedTime(); 3314 3315 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3316 workers()->run_task(&redirty_task); 3317 3318 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3319 dcq.merge_bufferlists(rdcqs); 3320 3321 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3322 } 3323 3324 // Weak Reference Processing support 3325 3326 bool G1STWIsAliveClosure::do_object_b(oop p) { 3327 // An object is reachable if it is outside the collection set, 3328 // or is inside and copied. 3329 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3330 } 3331 3332 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3333 assert(obj != NULL, "must not be NULL"); 3334 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3335 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3336 // may falsely indicate that this is not the case here: however the collection set only 3337 // contains old regions when concurrent mark is not running. 3338 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3339 } 3340 3341 // Non Copying Keep Alive closure 3342 class G1KeepAliveClosure: public OopClosure { 3343 G1CollectedHeap*_g1h; 3344 public: 3345 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3346 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3347 void do_oop(oop* p) { 3348 oop obj = *p; 3349 assert(obj != NULL, "the caller should have filtered out NULL values"); 3350 3351 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3352 if (!region_attr.is_in_cset_or_humongous()) { 3353 return; 3354 } 3355 if (region_attr.is_in_cset()) { 3356 assert( obj->is_forwarded(), "invariant" ); 3357 *p = obj->forwardee(); 3358 } else { 3359 assert(!obj->is_forwarded(), "invariant" ); 3360 assert(region_attr.is_humongous(), 3361 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3362 _g1h->set_humongous_is_live(obj); 3363 } 3364 } 3365 }; 3366 3367 // Copying Keep Alive closure - can be called from both 3368 // serial and parallel code as long as different worker 3369 // threads utilize different G1ParScanThreadState instances 3370 // and different queues. 3371 3372 class G1CopyingKeepAliveClosure: public OopClosure { 3373 G1CollectedHeap* _g1h; 3374 G1ParScanThreadState* _par_scan_state; 3375 3376 public: 3377 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3378 G1ParScanThreadState* pss): 3379 _g1h(g1h), 3380 _par_scan_state(pss) 3381 {} 3382 3383 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3384 virtual void do_oop( oop* p) { do_oop_work(p); } 3385 3386 template <class T> void do_oop_work(T* p) { 3387 oop obj = RawAccess<>::oop_load(p); 3388 3389 if (_g1h->is_in_cset_or_humongous(obj)) { 3390 // If the referent object has been forwarded (either copied 3391 // to a new location or to itself in the event of an 3392 // evacuation failure) then we need to update the reference 3393 // field and, if both reference and referent are in the G1 3394 // heap, update the RSet for the referent. 3395 // 3396 // If the referent has not been forwarded then we have to keep 3397 // it alive by policy. Therefore we have copy the referent. 3398 // 3399 // When the queue is drained (after each phase of reference processing) 3400 // the object and it's followers will be copied, the reference field set 3401 // to point to the new location, and the RSet updated. 3402 _par_scan_state->push_on_queue(p); 3403 } 3404 } 3405 }; 3406 3407 // Serial drain queue closure. Called as the 'complete_gc' 3408 // closure for each discovered list in some of the 3409 // reference processing phases. 3410 3411 class G1STWDrainQueueClosure: public VoidClosure { 3412 protected: 3413 G1CollectedHeap* _g1h; 3414 G1ParScanThreadState* _par_scan_state; 3415 3416 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3417 3418 public: 3419 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3420 _g1h(g1h), 3421 _par_scan_state(pss) 3422 { } 3423 3424 void do_void() { 3425 G1ParScanThreadState* const pss = par_scan_state(); 3426 pss->trim_queue(); 3427 } 3428 }; 3429 3430 // Parallel Reference Processing closures 3431 3432 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3433 // processing during G1 evacuation pauses. 3434 3435 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3436 private: 3437 G1CollectedHeap* _g1h; 3438 G1ParScanThreadStateSet* _pss; 3439 RefToScanQueueSet* _queues; 3440 WorkGang* _workers; 3441 3442 public: 3443 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3444 G1ParScanThreadStateSet* per_thread_states, 3445 WorkGang* workers, 3446 RefToScanQueueSet *task_queues) : 3447 _g1h(g1h), 3448 _pss(per_thread_states), 3449 _queues(task_queues), 3450 _workers(workers) 3451 { 3452 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3453 } 3454 3455 // Executes the given task using concurrent marking worker threads. 3456 virtual void execute(ProcessTask& task, uint ergo_workers); 3457 }; 3458 3459 // Gang task for possibly parallel reference processing 3460 3461 class G1STWRefProcTaskProxy: public AbstractGangTask { 3462 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3463 ProcessTask& _proc_task; 3464 G1CollectedHeap* _g1h; 3465 G1ParScanThreadStateSet* _pss; 3466 RefToScanQueueSet* _task_queues; 3467 TaskTerminator* _terminator; 3468 3469 public: 3470 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3471 G1CollectedHeap* g1h, 3472 G1ParScanThreadStateSet* per_thread_states, 3473 RefToScanQueueSet *task_queues, 3474 TaskTerminator* terminator) : 3475 AbstractGangTask("Process reference objects in parallel"), 3476 _proc_task(proc_task), 3477 _g1h(g1h), 3478 _pss(per_thread_states), 3479 _task_queues(task_queues), 3480 _terminator(terminator) 3481 {} 3482 3483 virtual void work(uint worker_id) { 3484 // The reference processing task executed by a single worker. 3485 ResourceMark rm; 3486 HandleMark hm; 3487 3488 G1STWIsAliveClosure is_alive(_g1h); 3489 3490 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3491 pss->set_ref_discoverer(NULL); 3492 3493 // Keep alive closure. 3494 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3495 3496 // Complete GC closure 3497 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3498 3499 // Call the reference processing task's work routine. 3500 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3501 3502 // Note we cannot assert that the refs array is empty here as not all 3503 // of the processing tasks (specifically phase2 - pp2_work) execute 3504 // the complete_gc closure (which ordinarily would drain the queue) so 3505 // the queue may not be empty. 3506 } 3507 }; 3508 3509 // Driver routine for parallel reference processing. 3510 // Creates an instance of the ref processing gang 3511 // task and has the worker threads execute it. 3512 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3513 assert(_workers != NULL, "Need parallel worker threads."); 3514 3515 assert(_workers->active_workers() >= ergo_workers, 3516 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3517 ergo_workers, _workers->active_workers()); 3518 TaskTerminator terminator(ergo_workers, _queues); 3519 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3520 3521 _workers->run_task(&proc_task_proxy, ergo_workers); 3522 } 3523 3524 // End of weak reference support closures 3525 3526 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3527 double ref_proc_start = os::elapsedTime(); 3528 3529 ReferenceProcessor* rp = _ref_processor_stw; 3530 assert(rp->discovery_enabled(), "should have been enabled"); 3531 3532 // Closure to test whether a referent is alive. 3533 G1STWIsAliveClosure is_alive(this); 3534 3535 // Even when parallel reference processing is enabled, the processing 3536 // of JNI refs is serial and performed serially by the current thread 3537 // rather than by a worker. The following PSS will be used for processing 3538 // JNI refs. 3539 3540 // Use only a single queue for this PSS. 3541 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3542 pss->set_ref_discoverer(NULL); 3543 assert(pss->queue_is_empty(), "pre-condition"); 3544 3545 // Keep alive closure. 3546 G1CopyingKeepAliveClosure keep_alive(this, pss); 3547 3548 // Serial Complete GC closure 3549 G1STWDrainQueueClosure drain_queue(this, pss); 3550 3551 // Setup the soft refs policy... 3552 rp->setup_policy(false); 3553 3554 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3555 3556 ReferenceProcessorStats stats; 3557 if (!rp->processing_is_mt()) { 3558 // Serial reference processing... 3559 stats = rp->process_discovered_references(&is_alive, 3560 &keep_alive, 3561 &drain_queue, 3562 NULL, 3563 pt); 3564 } else { 3565 uint no_of_gc_workers = workers()->active_workers(); 3566 3567 // Parallel reference processing 3568 assert(no_of_gc_workers <= rp->max_num_queues(), 3569 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3570 no_of_gc_workers, rp->max_num_queues()); 3571 3572 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3573 stats = rp->process_discovered_references(&is_alive, 3574 &keep_alive, 3575 &drain_queue, 3576 &par_task_executor, 3577 pt); 3578 } 3579 3580 _gc_tracer_stw->report_gc_reference_stats(stats); 3581 3582 // We have completed copying any necessary live referent objects. 3583 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3584 3585 make_pending_list_reachable(); 3586 3587 assert(!rp->discovery_enabled(), "Postcondition"); 3588 rp->verify_no_references_recorded(); 3589 3590 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3591 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3592 } 3593 3594 void G1CollectedHeap::make_pending_list_reachable() { 3595 if (collector_state()->in_initial_mark_gc()) { 3596 oop pll_head = Universe::reference_pending_list(); 3597 if (pll_head != NULL) { 3598 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3599 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3600 } 3601 } 3602 } 3603 3604 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3605 Ticks start = Ticks::now(); 3606 per_thread_states->flush(); 3607 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds()); 3608 } 3609 3610 class G1PrepareEvacuationTask : public AbstractGangTask { 3611 class G1PrepareRegionsClosure : public HeapRegionClosure { 3612 G1CollectedHeap* _g1h; 3613 G1PrepareEvacuationTask* _parent_task; 3614 size_t _worker_humongous_total; 3615 size_t _worker_humongous_candidates; 3616 3617 bool humongous_region_is_candidate(HeapRegion* region) const { 3618 assert(region->is_starts_humongous(), "Must start a humongous object"); 3619 3620 oop obj = oop(region->bottom()); 3621 3622 // Dead objects cannot be eager reclaim candidates. Due to class 3623 // unloading it is unsafe to query their classes so we return early. 3624 if (_g1h->is_obj_dead(obj, region)) { 3625 return false; 3626 } 3627 3628 // If we do not have a complete remembered set for the region, then we can 3629 // not be sure that we have all references to it. 3630 if (!region->rem_set()->is_complete()) { 3631 return false; 3632 } 3633 // Candidate selection must satisfy the following constraints 3634 // while concurrent marking is in progress: 3635 // 3636 // * In order to maintain SATB invariants, an object must not be 3637 // reclaimed if it was allocated before the start of marking and 3638 // has not had its references scanned. Such an object must have 3639 // its references (including type metadata) scanned to ensure no 3640 // live objects are missed by the marking process. Objects 3641 // allocated after the start of concurrent marking don't need to 3642 // be scanned. 3643 // 3644 // * An object must not be reclaimed if it is on the concurrent 3645 // mark stack. Objects allocated after the start of concurrent 3646 // marking are never pushed on the mark stack. 3647 // 3648 // Nominating only objects allocated after the start of concurrent 3649 // marking is sufficient to meet both constraints. This may miss 3650 // some objects that satisfy the constraints, but the marking data 3651 // structures don't support efficiently performing the needed 3652 // additional tests or scrubbing of the mark stack. 3653 // 3654 // However, we presently only nominate is_typeArray() objects. 3655 // A humongous object containing references induces remembered 3656 // set entries on other regions. In order to reclaim such an 3657 // object, those remembered sets would need to be cleaned up. 3658 // 3659 // We also treat is_typeArray() objects specially, allowing them 3660 // to be reclaimed even if allocated before the start of 3661 // concurrent mark. For this we rely on mark stack insertion to 3662 // exclude is_typeArray() objects, preventing reclaiming an object 3663 // that is in the mark stack. We also rely on the metadata for 3664 // such objects to be built-in and so ensured to be kept live. 3665 // Frequent allocation and drop of large binary blobs is an 3666 // important use case for eager reclaim, and this special handling 3667 // may reduce needed headroom. 3668 3669 return obj->is_typeArray() && 3670 _g1h->is_potential_eager_reclaim_candidate(region); 3671 } 3672 3673 public: 3674 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) : 3675 _g1h(g1h), 3676 _parent_task(parent_task), 3677 _worker_humongous_total(0), 3678 _worker_humongous_candidates(0) { } 3679 3680 ~G1PrepareRegionsClosure() { 3681 _parent_task->add_humongous_candidates(_worker_humongous_candidates); 3682 _parent_task->add_humongous_total(_worker_humongous_total); 3683 } 3684 3685 virtual bool do_heap_region(HeapRegion* hr) { 3686 // First prepare the region for scanning 3687 _g1h->rem_set()->prepare_region_for_scan(hr); 3688 3689 // Now check if region is a humongous candidate 3690 if (!hr->is_starts_humongous()) { 3691 _g1h->register_region_with_region_attr(hr); 3692 return false; 3693 } 3694 3695 uint index = hr->hrm_index(); 3696 if (humongous_region_is_candidate(hr)) { 3697 _g1h->set_humongous_reclaim_candidate(index, true); 3698 _g1h->register_humongous_region_with_region_attr(index); 3699 _worker_humongous_candidates++; 3700 // We will later handle the remembered sets of these regions. 3701 } else { 3702 _g1h->set_humongous_reclaim_candidate(index, false); 3703 _g1h->register_region_with_region_attr(hr); 3704 } 3705 _worker_humongous_total++; 3706 3707 return false; 3708 } 3709 }; 3710 3711 G1CollectedHeap* _g1h; 3712 HeapRegionClaimer _claimer; 3713 volatile size_t _humongous_total; 3714 volatile size_t _humongous_candidates; 3715 public: 3716 G1PrepareEvacuationTask(G1CollectedHeap* g1h) : 3717 AbstractGangTask("Prepare Evacuation"), 3718 _g1h(g1h), 3719 _claimer(_g1h->workers()->active_workers()), 3720 _humongous_total(0), 3721 _humongous_candidates(0) { } 3722 3723 ~G1PrepareEvacuationTask() { 3724 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0); 3725 } 3726 3727 void work(uint worker_id) { 3728 G1PrepareRegionsClosure cl(_g1h, this); 3729 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id); 3730 } 3731 3732 void add_humongous_candidates(size_t candidates) { 3733 Atomic::add(&_humongous_candidates, candidates); 3734 } 3735 3736 void add_humongous_total(size_t total) { 3737 Atomic::add(&_humongous_total, total); 3738 } 3739 3740 size_t humongous_candidates() { 3741 return _humongous_candidates; 3742 } 3743 3744 size_t humongous_total() { 3745 return _humongous_total; 3746 } 3747 }; 3748 3749 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3750 _bytes_used_during_gc = 0; 3751 3752 _expand_heap_after_alloc_failure = true; 3753 _evacuation_failed = false; 3754 3755 // Disable the hot card cache. 3756 _hot_card_cache->reset_hot_cache_claimed_index(); 3757 _hot_card_cache->set_use_cache(false); 3758 3759 // Initialize the GC alloc regions. 3760 _allocator->init_gc_alloc_regions(evacuation_info); 3761 3762 { 3763 Ticks start = Ticks::now(); 3764 rem_set()->prepare_for_scan_heap_roots(); 3765 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3766 } 3767 3768 { 3769 G1PrepareEvacuationTask g1_prep_task(this); 3770 Tickspan task_time = run_task(&g1_prep_task); 3771 3772 phase_times()->record_register_regions(task_time.seconds() * 1000.0, 3773 g1_prep_task.humongous_total(), 3774 g1_prep_task.humongous_candidates()); 3775 } 3776 3777 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3778 _preserved_marks_set.assert_empty(); 3779 3780 #if COMPILER2_OR_JVMCI 3781 DerivedPointerTable::clear(); 3782 #endif 3783 3784 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3785 if (collector_state()->in_initial_mark_gc()) { 3786 concurrent_mark()->pre_initial_mark(); 3787 3788 double start_clear_claimed_marks = os::elapsedTime(); 3789 3790 ClassLoaderDataGraph::clear_claimed_marks(); 3791 3792 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3793 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3794 } 3795 3796 // Should G1EvacuationFailureALot be in effect for this GC? 3797 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3798 } 3799 3800 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3801 protected: 3802 G1CollectedHeap* _g1h; 3803 G1ParScanThreadStateSet* _per_thread_states; 3804 RefToScanQueueSet* _task_queues; 3805 TaskTerminator _terminator; 3806 uint _num_workers; 3807 3808 void evacuate_live_objects(G1ParScanThreadState* pss, 3809 uint worker_id, 3810 G1GCPhaseTimes::GCParPhases objcopy_phase, 3811 G1GCPhaseTimes::GCParPhases termination_phase) { 3812 G1GCPhaseTimes* p = _g1h->phase_times(); 3813 3814 Ticks start = Ticks::now(); 3815 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase); 3816 cl.do_void(); 3817 3818 assert(pss->queue_is_empty(), "should be empty"); 3819 3820 Tickspan evac_time = (Ticks::now() - start); 3821 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3822 3823 if (termination_phase == G1GCPhaseTimes::Termination) { 3824 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3825 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3826 } else { 3827 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3828 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3829 } 3830 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3831 } 3832 3833 virtual void start_work(uint worker_id) { } 3834 3835 virtual void end_work(uint worker_id) { } 3836 3837 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3838 3839 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3840 3841 public: 3842 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3843 AbstractGangTask(name), 3844 _g1h(G1CollectedHeap::heap()), 3845 _per_thread_states(per_thread_states), 3846 _task_queues(task_queues), 3847 _terminator(num_workers, _task_queues), 3848 _num_workers(num_workers) 3849 { } 3850 3851 void work(uint worker_id) { 3852 start_work(worker_id); 3853 3854 { 3855 ResourceMark rm; 3856 HandleMark hm; 3857 3858 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3859 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3860 3861 scan_roots(pss, worker_id); 3862 evacuate_live_objects(pss, worker_id); 3863 } 3864 3865 end_work(worker_id); 3866 } 3867 }; 3868 3869 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3870 G1RootProcessor* _root_processor; 3871 3872 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3873 _root_processor->evacuate_roots(pss, worker_id); 3874 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3875 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3876 } 3877 3878 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3879 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3880 } 3881 3882 void start_work(uint worker_id) { 3883 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3884 } 3885 3886 void end_work(uint worker_id) { 3887 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3888 } 3889 3890 public: 3891 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3892 G1ParScanThreadStateSet* per_thread_states, 3893 RefToScanQueueSet* task_queues, 3894 G1RootProcessor* root_processor, 3895 uint num_workers) : 3896 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3897 _root_processor(root_processor) 3898 { } 3899 }; 3900 3901 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3902 G1GCPhaseTimes* p = phase_times(); 3903 3904 { 3905 Ticks start = Ticks::now(); 3906 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3907 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3908 } 3909 3910 Tickspan task_time; 3911 const uint num_workers = workers()->active_workers(); 3912 3913 Ticks start_processing = Ticks::now(); 3914 { 3915 G1RootProcessor root_processor(this, num_workers); 3916 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3917 task_time = run_task(&g1_par_task); 3918 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3919 // To extract its code root fixup time we measure total time of this scope and 3920 // subtract from the time the WorkGang task took. 3921 } 3922 Tickspan total_processing = Ticks::now() - start_processing; 3923 3924 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3925 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3926 } 3927 3928 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3929 3930 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3931 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3932 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3933 } 3934 3935 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3936 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3937 } 3938 3939 public: 3940 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3941 RefToScanQueueSet* queues, 3942 uint num_workers) : 3943 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3944 } 3945 }; 3946 3947 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3948 class G1MarkScope : public MarkScope { }; 3949 3950 Tickspan task_time; 3951 3952 Ticks start_processing = Ticks::now(); 3953 { 3954 G1MarkScope code_mark_scope; 3955 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3956 task_time = run_task(&task); 3957 // See comment in evacuate_collection_set() for the reason of the scope. 3958 } 3959 Tickspan total_processing = Ticks::now() - start_processing; 3960 3961 G1GCPhaseTimes* p = phase_times(); 3962 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3963 } 3964 3965 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3966 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3967 3968 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3969 3970 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3971 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3972 3973 if (time_left_ms < 0 || 3974 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3975 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3976 _collection_set.optional_region_length(), time_left_ms); 3977 break; 3978 } 3979 3980 { 3981 Ticks start = Ticks::now(); 3982 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3983 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3984 } 3985 3986 { 3987 Ticks start = Ticks::now(); 3988 evacuate_next_optional_regions(per_thread_states); 3989 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3990 } 3991 } 3992 3993 _collection_set.abandon_optional_collection_set(per_thread_states); 3994 } 3995 3996 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3997 G1RedirtyCardsQueueSet* rdcqs, 3998 G1ParScanThreadStateSet* per_thread_states) { 3999 G1GCPhaseTimes* p = phase_times(); 4000 4001 rem_set()->cleanup_after_scan_heap_roots(); 4002 4003 // Process any discovered reference objects - we have 4004 // to do this _before_ we retire the GC alloc regions 4005 // as we may have to copy some 'reachable' referent 4006 // objects (and their reachable sub-graphs) that were 4007 // not copied during the pause. 4008 process_discovered_references(per_thread_states); 4009 4010 G1STWIsAliveClosure is_alive(this); 4011 G1KeepAliveClosure keep_alive(this); 4012 4013 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times()); 4014 4015 if (G1StringDedup::is_enabled()) { 4016 double string_dedup_time_ms = os::elapsedTime(); 4017 4018 string_dedup_cleaning(&is_alive, &keep_alive, p); 4019 4020 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 4021 p->record_string_deduplication_time(string_cleanup_time_ms); 4022 } 4023 4024 _allocator->release_gc_alloc_regions(evacuation_info); 4025 4026 if (evacuation_failed()) { 4027 restore_after_evac_failure(rdcqs); 4028 4029 // Reset the G1EvacuationFailureALot counters and flags 4030 NOT_PRODUCT(reset_evacuation_should_fail();) 4031 4032 double recalculate_used_start = os::elapsedTime(); 4033 set_used(recalculate_used()); 4034 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 4035 4036 if (_archive_allocator != NULL) { 4037 _archive_allocator->clear_used(); 4038 } 4039 for (uint i = 0; i < ParallelGCThreads; i++) { 4040 if (_evacuation_failed_info_array[i].has_failed()) { 4041 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4042 } 4043 } 4044 } else { 4045 // The "used" of the the collection set have already been subtracted 4046 // when they were freed. Add in the bytes used. 4047 increase_used(_bytes_used_during_gc); 4048 } 4049 4050 _preserved_marks_set.assert_empty(); 4051 4052 merge_per_thread_state_info(per_thread_states); 4053 4054 // Reset and re-enable the hot card cache. 4055 // Note the counts for the cards in the regions in the 4056 // collection set are reset when the collection set is freed. 4057 _hot_card_cache->reset_hot_cache(); 4058 _hot_card_cache->set_use_cache(true); 4059 4060 purge_code_root_memory(); 4061 4062 redirty_logged_cards(rdcqs); 4063 4064 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4065 4066 eagerly_reclaim_humongous_regions(); 4067 4068 record_obj_copy_mem_stats(); 4069 4070 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4071 evacuation_info.set_bytes_used(_bytes_used_during_gc); 4072 4073 #if COMPILER2_OR_JVMCI 4074 double start = os::elapsedTime(); 4075 DerivedPointerTable::update_pointers(); 4076 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4077 #endif 4078 policy()->print_age_table(); 4079 } 4080 4081 void G1CollectedHeap::record_obj_copy_mem_stats() { 4082 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4083 4084 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4085 create_g1_evac_summary(&_old_evac_stats)); 4086 } 4087 4088 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 4089 assert(!hr->is_free(), "the region should not be free"); 4090 assert(!hr->is_empty(), "the region should not be empty"); 4091 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4092 4093 if (G1VerifyBitmaps) { 4094 MemRegion mr(hr->bottom(), hr->end()); 4095 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4096 } 4097 4098 // Clear the card counts for this region. 4099 // Note: we only need to do this if the region is not young 4100 // (since we don't refine cards in young regions). 4101 if (!hr->is_young()) { 4102 _hot_card_cache->reset_card_counts(hr); 4103 } 4104 4105 // Reset region metadata to allow reuse. 4106 hr->hr_clear(true /* clear_space */); 4107 _policy->remset_tracker()->update_at_free(hr); 4108 4109 if (free_list != NULL) { 4110 free_list->add_ordered(hr); 4111 } 4112 } 4113 4114 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4115 FreeRegionList* free_list) { 4116 assert(hr->is_humongous(), "this is only for humongous regions"); 4117 assert(free_list != NULL, "pre-condition"); 4118 hr->clear_humongous(); 4119 free_region(hr, free_list); 4120 } 4121 4122 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4123 const uint humongous_regions_removed) { 4124 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4125 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4126 _old_set.bulk_remove(old_regions_removed); 4127 _humongous_set.bulk_remove(humongous_regions_removed); 4128 } 4129 4130 } 4131 4132 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4133 assert(list != NULL, "list can't be null"); 4134 if (!list->is_empty()) { 4135 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4136 _hrm->insert_list_into_free_list(list); 4137 } 4138 } 4139 4140 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4141 decrease_used(bytes); 4142 } 4143 4144 class G1FreeCollectionSetTask : public AbstractGangTask { 4145 // Helper class to keep statistics for the collection set freeing 4146 class FreeCSetStats { 4147 size_t _before_used_bytes; // Usage in regions successfully evacutate 4148 size_t _after_used_bytes; // Usage in regions failing evacuation 4149 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old 4150 size_t _failure_used_words; // Live size in failed regions 4151 size_t _failure_waste_words; // Wasted size in failed regions 4152 size_t _rs_length; // Remembered set size 4153 uint _regions_freed; // Number of regions freed 4154 public: 4155 FreeCSetStats() : 4156 _before_used_bytes(0), 4157 _after_used_bytes(0), 4158 _bytes_allocated_in_old_since_last_gc(0), 4159 _failure_used_words(0), 4160 _failure_waste_words(0), 4161 _rs_length(0), 4162 _regions_freed(0) { } 4163 4164 void merge_stats(FreeCSetStats* other) { 4165 assert(other != NULL, "invariant"); 4166 _before_used_bytes += other->_before_used_bytes; 4167 _after_used_bytes += other->_after_used_bytes; 4168 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc; 4169 _failure_used_words += other->_failure_used_words; 4170 _failure_waste_words += other->_failure_waste_words; 4171 _rs_length += other->_rs_length; 4172 _regions_freed += other->_regions_freed; 4173 } 4174 4175 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) { 4176 evacuation_info->set_regions_freed(_regions_freed); 4177 evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4178 4179 g1h->decrement_summary_bytes(_before_used_bytes); 4180 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4181 4182 G1Policy *policy = g1h->policy(); 4183 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4184 policy->record_rs_length(_rs_length); 4185 policy->cset_regions_freed(); 4186 } 4187 4188 void account_failed_region(HeapRegion* r) { 4189 size_t used_words = r->marked_bytes() / HeapWordSize; 4190 _failure_used_words += used_words; 4191 _failure_waste_words += HeapRegion::GrainWords - used_words; 4192 _after_used_bytes += r->used(); 4193 4194 // When moving a young gen region to old gen, we "allocate" that whole 4195 // region there. This is in addition to any already evacuated objects. 4196 // Notify the policy about that. Old gen regions do not cause an 4197 // additional allocation: both the objects still in the region and the 4198 // ones already moved are accounted for elsewhere. 4199 if (r->is_young()) { 4200 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4201 } 4202 } 4203 4204 void account_evacuated_region(HeapRegion* r) { 4205 _before_used_bytes += r->used(); 4206 _regions_freed += 1; 4207 } 4208 4209 void account_rs_length(HeapRegion* r) { 4210 _rs_length += r->rem_set()->occupied(); 4211 } 4212 }; 4213 4214 // Closure applied to all regions in the collection set. 4215 class FreeCSetClosure : public HeapRegionClosure { 4216 // Helper to send JFR events for regions. 4217 class JFREventForRegion { 4218 EventGCPhaseParallel _event; 4219 public: 4220 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() { 4221 _event.set_gcId(GCId::current()); 4222 _event.set_gcWorkerId(worker_id); 4223 if (region->is_young()) { 4224 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4225 } else { 4226 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4227 } 4228 } 4229 4230 ~JFREventForRegion() { 4231 _event.commit(); 4232 } 4233 }; 4234 4235 // Helper to do timing for region work. 4236 class TimerForRegion { 4237 Tickspan& _time; 4238 Ticks _start_time; 4239 public: 4240 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { } 4241 ~TimerForRegion() { 4242 _time += Ticks::now() - _start_time; 4243 } 4244 }; 4245 4246 // FreeCSetClosure members 4247 G1CollectedHeap* _g1h; 4248 const size_t* _surviving_young_words; 4249 uint _worker_id; 4250 Tickspan _young_time; 4251 Tickspan _non_young_time; 4252 FreeCSetStats* _stats; 4253 4254 void assert_in_cset(HeapRegion* r) { 4255 assert(r->young_index_in_cset() != 0 && 4256 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(), 4257 "Young index %u is wrong for region %u of type %s with %u young regions", 4258 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length()); 4259 } 4260 4261 void handle_evacuated_region(HeapRegion* r) { 4262 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4263 stats()->account_evacuated_region(r); 4264 4265 // Free the region and and its remembered set. 4266 _g1h->free_region(r, NULL); 4267 } 4268 4269 void handle_failed_region(HeapRegion* r) { 4270 // Do some allocation statistics accounting. Regions that failed evacuation 4271 // are always made old, so there is no need to update anything in the young 4272 // gen statistics, but we need to update old gen statistics. 4273 stats()->account_failed_region(r); 4274 4275 // Update the region state due to the failed evacuation. 4276 r->handle_evacuation_failure(); 4277 4278 // Add region to old set, need to hold lock. 4279 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4280 _g1h->old_set_add(r); 4281 } 4282 4283 Tickspan& timer_for_region(HeapRegion* r) { 4284 return r->is_young() ? _young_time : _non_young_time; 4285 } 4286 4287 FreeCSetStats* stats() { 4288 return _stats; 4289 } 4290 public: 4291 FreeCSetClosure(const size_t* surviving_young_words, 4292 uint worker_id, 4293 FreeCSetStats* stats) : 4294 HeapRegionClosure(), 4295 _g1h(G1CollectedHeap::heap()), 4296 _surviving_young_words(surviving_young_words), 4297 _worker_id(worker_id), 4298 _young_time(), 4299 _non_young_time(), 4300 _stats(stats) { } 4301 4302 virtual bool do_heap_region(HeapRegion* r) { 4303 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index()); 4304 JFREventForRegion event(r, _worker_id); 4305 TimerForRegion timer(timer_for_region(r)); 4306 4307 _g1h->clear_region_attr(r); 4308 stats()->account_rs_length(r); 4309 4310 if (r->is_young()) { 4311 assert_in_cset(r); 4312 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]); 4313 } 4314 4315 if (r->evacuation_failed()) { 4316 handle_failed_region(r); 4317 } else { 4318 handle_evacuated_region(r); 4319 } 4320 assert(!_g1h->is_on_master_free_list(r), "sanity"); 4321 4322 return false; 4323 } 4324 4325 void report_timing(Tickspan parallel_time) { 4326 G1GCPhaseTimes* pt = _g1h->phase_times(); 4327 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds()); 4328 if (_young_time.value() > 0) { 4329 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds()); 4330 } 4331 if (_non_young_time.value() > 0) { 4332 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds()); 4333 } 4334 } 4335 }; 4336 4337 // G1FreeCollectionSetTask members 4338 G1CollectedHeap* _g1h; 4339 G1EvacuationInfo* _evacuation_info; 4340 FreeCSetStats* _worker_stats; 4341 HeapRegionClaimer _claimer; 4342 const size_t* _surviving_young_words; 4343 uint _active_workers; 4344 4345 FreeCSetStats* worker_stats(uint worker) { 4346 return &_worker_stats[worker]; 4347 } 4348 4349 void report_statistics() { 4350 // Merge the accounting 4351 FreeCSetStats total_stats; 4352 for (uint worker = 0; worker < _active_workers; worker++) { 4353 total_stats.merge_stats(worker_stats(worker)); 4354 } 4355 total_stats.report(_g1h, _evacuation_info); 4356 } 4357 4358 public: 4359 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) : 4360 AbstractGangTask("G1 Free Collection Set"), 4361 _g1h(G1CollectedHeap::heap()), 4362 _evacuation_info(evacuation_info), 4363 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)), 4364 _claimer(active_workers), 4365 _surviving_young_words(surviving_young_words), 4366 _active_workers(active_workers) { 4367 for (uint worker = 0; worker < active_workers; worker++) { 4368 ::new (&_worker_stats[worker]) FreeCSetStats(); 4369 } 4370 } 4371 4372 ~G1FreeCollectionSetTask() { 4373 Ticks serial_time = Ticks::now(); 4374 report_statistics(); 4375 for (uint worker = 0; worker < _active_workers; worker++) { 4376 _worker_stats[worker].~FreeCSetStats(); 4377 } 4378 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats); 4379 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0); 4380 } 4381 4382 virtual void work(uint worker_id) { 4383 EventGCPhaseParallel event; 4384 Ticks start = Ticks::now(); 4385 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id)); 4386 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id); 4387 4388 // Report the total parallel time along with some more detailed metrics. 4389 cl.report_timing(Ticks::now() - start); 4390 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet)); 4391 } 4392 }; 4393 4394 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4395 _eden.clear(); 4396 4397 // The free collections set is split up in two tasks, the first 4398 // frees the collection set and records what regions are free, 4399 // and the second one rebuilds the free list. This proved to be 4400 // more efficient than adding a sorted list to another. 4401 4402 Ticks free_cset_start_time = Ticks::now(); 4403 { 4404 uint const num_cs_regions = _collection_set.region_length(); 4405 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers()); 4406 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers); 4407 4408 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)", 4409 cl.name(), num_workers, num_cs_regions, num_regions()); 4410 workers()->run_task(&cl, num_workers); 4411 } 4412 4413 Ticks free_cset_end_time = Ticks::now(); 4414 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0); 4415 4416 // Now rebuild the free region list. 4417 hrm()->rebuild_free_list(workers()); 4418 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0); 4419 4420 collection_set->clear(); 4421 } 4422 4423 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4424 private: 4425 FreeRegionList* _free_region_list; 4426 HeapRegionSet* _proxy_set; 4427 uint _humongous_objects_reclaimed; 4428 uint _humongous_regions_reclaimed; 4429 size_t _freed_bytes; 4430 public: 4431 4432 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4433 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4434 } 4435 4436 virtual bool do_heap_region(HeapRegion* r) { 4437 if (!r->is_starts_humongous()) { 4438 return false; 4439 } 4440 4441 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4442 4443 oop obj = (oop)r->bottom(); 4444 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4445 4446 // The following checks whether the humongous object is live are sufficient. 4447 // The main additional check (in addition to having a reference from the roots 4448 // or the young gen) is whether the humongous object has a remembered set entry. 4449 // 4450 // A humongous object cannot be live if there is no remembered set for it 4451 // because: 4452 // - there can be no references from within humongous starts regions referencing 4453 // the object because we never allocate other objects into them. 4454 // (I.e. there are no intra-region references that may be missed by the 4455 // remembered set) 4456 // - as soon there is a remembered set entry to the humongous starts region 4457 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4458 // until the end of a concurrent mark. 4459 // 4460 // It is not required to check whether the object has been found dead by marking 4461 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4462 // all objects allocated during that time are considered live. 4463 // SATB marking is even more conservative than the remembered set. 4464 // So if at this point in the collection there is no remembered set entry, 4465 // nobody has a reference to it. 4466 // At the start of collection we flush all refinement logs, and remembered sets 4467 // are completely up-to-date wrt to references to the humongous object. 4468 // 4469 // Other implementation considerations: 4470 // - never consider object arrays at this time because they would pose 4471 // considerable effort for cleaning up the the remembered sets. This is 4472 // required because stale remembered sets might reference locations that 4473 // are currently allocated into. 4474 uint region_idx = r->hrm_index(); 4475 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4476 !r->rem_set()->is_empty()) { 4477 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", 4478 region_idx, 4479 (size_t)obj->size() * HeapWordSize, 4480 p2i(r->bottom()), 4481 r->rem_set()->occupied(), 4482 r->rem_set()->strong_code_roots_list_length(), 4483 next_bitmap->is_marked(r->bottom()), 4484 g1h->is_humongous_reclaim_candidate(region_idx), 4485 obj->is_typeArray() 4486 ); 4487 return false; 4488 } 4489 4490 guarantee(obj->is_typeArray(), 4491 "Only eagerly reclaiming type arrays is supported, but the object " 4492 PTR_FORMAT " is not.", p2i(r->bottom())); 4493 4494 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", 4495 region_idx, 4496 (size_t)obj->size() * HeapWordSize, 4497 p2i(r->bottom()), 4498 r->rem_set()->occupied(), 4499 r->rem_set()->strong_code_roots_list_length(), 4500 next_bitmap->is_marked(r->bottom()), 4501 g1h->is_humongous_reclaim_candidate(region_idx), 4502 obj->is_typeArray() 4503 ); 4504 4505 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4506 cm->humongous_object_eagerly_reclaimed(r); 4507 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4508 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4509 region_idx, 4510 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4511 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4512 _humongous_objects_reclaimed++; 4513 do { 4514 HeapRegion* next = g1h->next_region_in_humongous(r); 4515 _freed_bytes += r->used(); 4516 r->set_containing_set(NULL); 4517 _humongous_regions_reclaimed++; 4518 g1h->free_humongous_region(r, _free_region_list); 4519 r = next; 4520 } while (r != NULL); 4521 4522 return false; 4523 } 4524 4525 uint humongous_objects_reclaimed() { 4526 return _humongous_objects_reclaimed; 4527 } 4528 4529 uint humongous_regions_reclaimed() { 4530 return _humongous_regions_reclaimed; 4531 } 4532 4533 size_t bytes_freed() const { 4534 return _freed_bytes; 4535 } 4536 }; 4537 4538 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4539 assert_at_safepoint_on_vm_thread(); 4540 4541 if (!G1EagerReclaimHumongousObjects || 4542 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4543 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4544 return; 4545 } 4546 4547 double start_time = os::elapsedTime(); 4548 4549 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4550 4551 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4552 heap_region_iterate(&cl); 4553 4554 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4555 4556 G1HRPrinter* hrp = hr_printer(); 4557 if (hrp->is_active()) { 4558 FreeRegionListIterator iter(&local_cleanup_list); 4559 while (iter.more_available()) { 4560 HeapRegion* hr = iter.get_next(); 4561 hrp->cleanup(hr); 4562 } 4563 } 4564 4565 prepend_to_freelist(&local_cleanup_list); 4566 decrement_summary_bytes(cl.bytes_freed()); 4567 4568 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4569 cl.humongous_objects_reclaimed()); 4570 } 4571 4572 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4573 public: 4574 virtual bool do_heap_region(HeapRegion* r) { 4575 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4576 G1CollectedHeap::heap()->clear_region_attr(r); 4577 r->clear_young_index_in_cset(); 4578 return false; 4579 } 4580 }; 4581 4582 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4583 G1AbandonCollectionSetClosure cl; 4584 collection_set_iterate_all(&cl); 4585 4586 collection_set->clear(); 4587 collection_set->stop_incremental_building(); 4588 } 4589 4590 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4591 return _allocator->is_retained_old_region(hr); 4592 } 4593 4594 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4595 _eden.add(hr); 4596 _policy->set_region_eden(hr); 4597 } 4598 4599 #ifdef ASSERT 4600 4601 class NoYoungRegionsClosure: public HeapRegionClosure { 4602 private: 4603 bool _success; 4604 public: 4605 NoYoungRegionsClosure() : _success(true) { } 4606 bool do_heap_region(HeapRegion* r) { 4607 if (r->is_young()) { 4608 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4609 p2i(r->bottom()), p2i(r->end())); 4610 _success = false; 4611 } 4612 return false; 4613 } 4614 bool success() { return _success; } 4615 }; 4616 4617 bool G1CollectedHeap::check_young_list_empty() { 4618 bool ret = (young_regions_count() == 0); 4619 4620 NoYoungRegionsClosure closure; 4621 heap_region_iterate(&closure); 4622 ret = ret && closure.success(); 4623 4624 return ret; 4625 } 4626 4627 #endif // ASSERT 4628 4629 class TearDownRegionSetsClosure : public HeapRegionClosure { 4630 HeapRegionSet *_old_set; 4631 4632 public: 4633 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4634 4635 bool do_heap_region(HeapRegion* r) { 4636 if (r->is_old()) { 4637 _old_set->remove(r); 4638 } else if(r->is_young()) { 4639 r->uninstall_surv_rate_group(); 4640 } else { 4641 // We ignore free regions, we'll empty the free list afterwards. 4642 // We ignore humongous and archive regions, we're not tearing down these 4643 // sets. 4644 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4645 "it cannot be another type"); 4646 } 4647 return false; 4648 } 4649 4650 ~TearDownRegionSetsClosure() { 4651 assert(_old_set->is_empty(), "post-condition"); 4652 } 4653 }; 4654 4655 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4656 assert_at_safepoint_on_vm_thread(); 4657 4658 if (!free_list_only) { 4659 TearDownRegionSetsClosure cl(&_old_set); 4660 heap_region_iterate(&cl); 4661 4662 // Note that emptying the _young_list is postponed and instead done as 4663 // the first step when rebuilding the regions sets again. The reason for 4664 // this is that during a full GC string deduplication needs to know if 4665 // a collected region was young or old when the full GC was initiated. 4666 } 4667 _hrm->remove_all_free_regions(); 4668 } 4669 4670 void G1CollectedHeap::increase_used(size_t bytes) { 4671 _summary_bytes_used += bytes; 4672 } 4673 4674 void G1CollectedHeap::decrease_used(size_t bytes) { 4675 assert(_summary_bytes_used >= bytes, 4676 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4677 _summary_bytes_used, bytes); 4678 _summary_bytes_used -= bytes; 4679 } 4680 4681 void G1CollectedHeap::set_used(size_t bytes) { 4682 _summary_bytes_used = bytes; 4683 } 4684 4685 class RebuildRegionSetsClosure : public HeapRegionClosure { 4686 private: 4687 bool _free_list_only; 4688 4689 HeapRegionSet* _old_set; 4690 HeapRegionManager* _hrm; 4691 4692 size_t _total_used; 4693 4694 public: 4695 RebuildRegionSetsClosure(bool free_list_only, 4696 HeapRegionSet* old_set, 4697 HeapRegionManager* hrm) : 4698 _free_list_only(free_list_only), 4699 _old_set(old_set), _hrm(hrm), _total_used(0) { 4700 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4701 if (!free_list_only) { 4702 assert(_old_set->is_empty(), "pre-condition"); 4703 } 4704 } 4705 4706 bool do_heap_region(HeapRegion* r) { 4707 if (r->is_empty()) { 4708 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4709 // Add free regions to the free list 4710 r->set_free(); 4711 _hrm->insert_into_free_list(r); 4712 } else if (!_free_list_only) { 4713 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4714 4715 if (r->is_archive() || r->is_humongous()) { 4716 // We ignore archive and humongous regions. We left these sets unchanged. 4717 } else { 4718 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4719 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4720 r->move_to_old(); 4721 _old_set->add(r); 4722 } 4723 _total_used += r->used(); 4724 } 4725 4726 return false; 4727 } 4728 4729 size_t total_used() { 4730 return _total_used; 4731 } 4732 }; 4733 4734 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4735 assert_at_safepoint_on_vm_thread(); 4736 4737 if (!free_list_only) { 4738 _eden.clear(); 4739 _survivor.clear(); 4740 } 4741 4742 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4743 heap_region_iterate(&cl); 4744 4745 if (!free_list_only) { 4746 set_used(cl.total_used()); 4747 if (_archive_allocator != NULL) { 4748 _archive_allocator->clear_used(); 4749 } 4750 } 4751 assert_used_and_recalculate_used_equal(this); 4752 } 4753 4754 // Methods for the mutator alloc region 4755 4756 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4757 bool force, 4758 uint node_index) { 4759 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4760 bool should_allocate = policy()->should_allocate_mutator_region(); 4761 if (force || should_allocate) { 4762 HeapRegion* new_alloc_region = new_region(word_size, 4763 HeapRegionType::Eden, 4764 false /* do_expand */, 4765 node_index); 4766 if (new_alloc_region != NULL) { 4767 set_region_short_lived_locked(new_alloc_region); 4768 _hr_printer.alloc(new_alloc_region, !should_allocate); 4769 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4770 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4771 return new_alloc_region; 4772 } 4773 } 4774 return NULL; 4775 } 4776 4777 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4778 size_t allocated_bytes) { 4779 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4780 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4781 4782 collection_set()->add_eden_region(alloc_region); 4783 increase_used(allocated_bytes); 4784 _eden.add_used_bytes(allocated_bytes); 4785 _hr_printer.retire(alloc_region); 4786 4787 // We update the eden sizes here, when the region is retired, 4788 // instead of when it's allocated, since this is the point that its 4789 // used space has been recorded in _summary_bytes_used. 4790 g1mm()->update_eden_size(); 4791 } 4792 4793 // Methods for the GC alloc regions 4794 4795 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4796 if (dest.is_old()) { 4797 return true; 4798 } else { 4799 return survivor_regions_count() < policy()->max_survivor_regions(); 4800 } 4801 } 4802 4803 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4804 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4805 4806 if (!has_more_regions(dest)) { 4807 return NULL; 4808 } 4809 4810 HeapRegionType type; 4811 if (dest.is_young()) { 4812 type = HeapRegionType::Survivor; 4813 } else { 4814 type = HeapRegionType::Old; 4815 } 4816 4817 HeapRegion* new_alloc_region = new_region(word_size, 4818 type, 4819 true /* do_expand */, 4820 node_index); 4821 4822 if (new_alloc_region != NULL) { 4823 if (type.is_survivor()) { 4824 new_alloc_region->set_survivor(); 4825 _survivor.add(new_alloc_region); 4826 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4827 } else { 4828 new_alloc_region->set_old(); 4829 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4830 } 4831 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4832 register_region_with_region_attr(new_alloc_region); 4833 _hr_printer.alloc(new_alloc_region); 4834 return new_alloc_region; 4835 } 4836 return NULL; 4837 } 4838 4839 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4840 size_t allocated_bytes, 4841 G1HeapRegionAttr dest) { 4842 _bytes_used_during_gc += allocated_bytes; 4843 if (dest.is_old()) { 4844 old_set_add(alloc_region); 4845 } else { 4846 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4847 _survivor.add_used_bytes(allocated_bytes); 4848 } 4849 4850 bool const during_im = collector_state()->in_initial_mark_gc(); 4851 if (during_im && allocated_bytes > 0) { 4852 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4853 } 4854 _hr_printer.retire(alloc_region); 4855 } 4856 4857 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4858 bool expanded = false; 4859 uint index = _hrm->find_highest_free(&expanded); 4860 4861 if (index != G1_NO_HRM_INDEX) { 4862 if (expanded) { 4863 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4864 HeapRegion::GrainWords * HeapWordSize); 4865 } 4866 return _hrm->allocate_free_regions_starting_at(index, 1); 4867 } 4868 return NULL; 4869 } 4870 4871 // Optimized nmethod scanning 4872 4873 class RegisterNMethodOopClosure: public OopClosure { 4874 G1CollectedHeap* _g1h; 4875 nmethod* _nm; 4876 4877 template <class T> void do_oop_work(T* p) { 4878 T heap_oop = RawAccess<>::oop_load(p); 4879 if (!CompressedOops::is_null(heap_oop)) { 4880 oop obj = CompressedOops::decode_not_null(heap_oop); 4881 HeapRegion* hr = _g1h->heap_region_containing(obj); 4882 assert(!hr->is_continues_humongous(), 4883 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4884 " starting at " HR_FORMAT, 4885 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4886 4887 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4888 hr->add_strong_code_root_locked(_nm); 4889 } 4890 } 4891 4892 public: 4893 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4894 _g1h(g1h), _nm(nm) {} 4895 4896 void do_oop(oop* p) { do_oop_work(p); } 4897 void do_oop(narrowOop* p) { do_oop_work(p); } 4898 }; 4899 4900 class UnregisterNMethodOopClosure: public OopClosure { 4901 G1CollectedHeap* _g1h; 4902 nmethod* _nm; 4903 4904 template <class T> void do_oop_work(T* p) { 4905 T heap_oop = RawAccess<>::oop_load(p); 4906 if (!CompressedOops::is_null(heap_oop)) { 4907 oop obj = CompressedOops::decode_not_null(heap_oop); 4908 HeapRegion* hr = _g1h->heap_region_containing(obj); 4909 assert(!hr->is_continues_humongous(), 4910 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4911 " starting at " HR_FORMAT, 4912 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4913 4914 hr->remove_strong_code_root(_nm); 4915 } 4916 } 4917 4918 public: 4919 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4920 _g1h(g1h), _nm(nm) {} 4921 4922 void do_oop(oop* p) { do_oop_work(p); } 4923 void do_oop(narrowOop* p) { do_oop_work(p); } 4924 }; 4925 4926 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4927 guarantee(nm != NULL, "sanity"); 4928 RegisterNMethodOopClosure reg_cl(this, nm); 4929 nm->oops_do(®_cl); 4930 } 4931 4932 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4933 guarantee(nm != NULL, "sanity"); 4934 UnregisterNMethodOopClosure reg_cl(this, nm); 4935 nm->oops_do(®_cl, true); 4936 } 4937 4938 void G1CollectedHeap::purge_code_root_memory() { 4939 double purge_start = os::elapsedTime(); 4940 G1CodeRootSet::purge(); 4941 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4942 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4943 } 4944 4945 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4946 G1CollectedHeap* _g1h; 4947 4948 public: 4949 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4950 _g1h(g1h) {} 4951 4952 void do_code_blob(CodeBlob* cb) { 4953 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4954 if (nm == NULL) { 4955 return; 4956 } 4957 4958 _g1h->register_nmethod(nm); 4959 } 4960 }; 4961 4962 void G1CollectedHeap::rebuild_strong_code_roots() { 4963 RebuildStrongCodeRootClosure blob_cl(this); 4964 CodeCache::blobs_do(&blob_cl); 4965 } 4966 4967 void G1CollectedHeap::initialize_serviceability() { 4968 _g1mm->initialize_serviceability(); 4969 } 4970 4971 MemoryUsage G1CollectedHeap::memory_usage() { 4972 return _g1mm->memory_usage(); 4973 } 4974 4975 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4976 return _g1mm->memory_managers(); 4977 } 4978 4979 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4980 return _g1mm->memory_pools(); 4981 }