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/g1GCPhaseTimes.hpp" 45 #include "gc/g1/g1HeapSizingPolicy.hpp" 46 #include "gc/g1/g1HeapTransition.hpp" 47 #include "gc/g1/g1HeapVerifier.hpp" 48 #include "gc/g1/g1HotCardCache.hpp" 49 #include "gc/g1/g1MemoryPool.hpp" 50 #include "gc/g1/g1OopClosures.inline.hpp" 51 #include "gc/g1/g1ParallelCleaning.hpp" 52 #include "gc/g1/g1ParScanThreadState.inline.hpp" 53 #include "gc/g1/g1Policy.hpp" 54 #include "gc/g1/g1RedirtyCardsQueue.hpp" 55 #include "gc/g1/g1RegionToSpaceMapper.hpp" 56 #include "gc/g1/g1RemSet.hpp" 57 #include "gc/g1/g1RootClosures.hpp" 58 #include "gc/g1/g1RootProcessor.hpp" 59 #include "gc/g1/g1SATBMarkQueueSet.hpp" 60 #include "gc/g1/g1StringDedup.hpp" 61 #include "gc/g1/g1ThreadLocalData.hpp" 62 #include "gc/g1/g1Trace.hpp" 63 #include "gc/g1/g1YCTypes.hpp" 64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 65 #include "gc/g1/g1VMOperations.hpp" 66 #include "gc/g1/heapRegion.inline.hpp" 67 #include "gc/g1/heapRegionRemSet.hpp" 68 #include "gc/g1/heapRegionSet.inline.hpp" 69 #include "gc/shared/concurrentGCBreakpoints.hpp" 70 #include "gc/shared/gcBehaviours.hpp" 71 #include "gc/shared/gcHeapSummary.hpp" 72 #include "gc/shared/gcId.hpp" 73 #include "gc/shared/gcLocker.hpp" 74 #include "gc/shared/gcTimer.hpp" 75 #include "gc/shared/gcTraceTime.inline.hpp" 76 #include "gc/shared/generationSpec.hpp" 77 #include "gc/shared/isGCActiveMark.hpp" 78 #include "gc/shared/locationPrinter.inline.hpp" 79 #include "gc/shared/oopStorageParState.hpp" 80 #include "gc/shared/preservedMarks.inline.hpp" 81 #include "gc/shared/suspendibleThreadSet.hpp" 82 #include "gc/shared/referenceProcessor.inline.hpp" 83 #include "gc/shared/taskTerminator.hpp" 84 #include "gc/shared/taskqueue.inline.hpp" 85 #include "gc/shared/weakProcessor.inline.hpp" 86 #include "gc/shared/workerPolicy.hpp" 87 #include "logging/log.hpp" 88 #include "memory/allocation.hpp" 89 #include "memory/iterator.hpp" 90 #include "memory/resourceArea.hpp" 91 #include "memory/universe.hpp" 92 #include "oops/access.inline.hpp" 93 #include "oops/compressedOops.inline.hpp" 94 #include "oops/oop.inline.hpp" 95 #include "runtime/atomic.hpp" 96 #include "runtime/flags/flagSetting.hpp" 97 #include "runtime/handles.inline.hpp" 98 #include "runtime/init.hpp" 99 #include "runtime/orderAccess.hpp" 100 #include "runtime/threadSMR.hpp" 101 #include "runtime/vmThread.hpp" 102 #include "utilities/align.hpp" 103 #include "utilities/bitMap.inline.hpp" 104 #include "utilities/globalDefinitions.hpp" 105 #include "utilities/stack.inline.hpp" 106 107 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 108 109 // INVARIANTS/NOTES 110 // 111 // All allocation activity covered by the G1CollectedHeap interface is 112 // serialized by acquiring the HeapLock. This happens in mem_allocate 113 // and allocate_new_tlab, which are the "entry" points to the 114 // allocation code from the rest of the JVM. (Note that this does not 115 // apply to TLAB allocation, which is not part of this interface: it 116 // is done by clients of this interface.) 117 118 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 119 private: 120 size_t _num_dirtied; 121 G1CollectedHeap* _g1h; 122 G1CardTable* _g1_ct; 123 124 HeapRegion* region_for_card(CardValue* card_ptr) const { 125 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 126 } 127 128 bool will_become_free(HeapRegion* hr) const { 129 // A region will be freed by free_collection_set if the region is in the 130 // collection set and has not had an evacuation failure. 131 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 132 } 133 134 public: 135 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 136 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 137 138 void do_card_ptr(CardValue* card_ptr, uint worker_id) { 139 HeapRegion* hr = region_for_card(card_ptr); 140 141 // Should only dirty cards in regions that won't be freed. 142 if (!will_become_free(hr)) { 143 *card_ptr = G1CardTable::dirty_card_val(); 144 _num_dirtied++; 145 } 146 } 147 148 size_t num_dirtied() const { return _num_dirtied; } 149 }; 150 151 152 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 153 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 154 } 155 156 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 157 // The from card cache is not the memory that is actually committed. So we cannot 158 // take advantage of the zero_filled parameter. 159 reset_from_card_cache(start_idx, num_regions); 160 } 161 162 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) { 163 Ticks start = Ticks::now(); 164 workers()->run_task(task, workers()->active_workers()); 165 return Ticks::now() - start; 166 } 167 168 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 169 MemRegion mr) { 170 return new HeapRegion(hrs_index, bot(), mr); 171 } 172 173 // Private methods. 174 175 HeapRegion* G1CollectedHeap::new_region(size_t word_size, 176 HeapRegionType type, 177 bool do_expand, 178 uint node_index) { 179 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 180 "the only time we use this to allocate a humongous region is " 181 "when we are allocating a single humongous region"); 182 183 HeapRegion* res = _hrm->allocate_free_region(type, node_index); 184 185 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 186 // Currently, only attempts to allocate GC alloc regions set 187 // do_expand to true. So, we should only reach here during a 188 // safepoint. If this assumption changes we might have to 189 // reconsider the use of _expand_heap_after_alloc_failure. 190 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 191 192 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 193 word_size * HeapWordSize); 194 195 assert(word_size * HeapWordSize < HeapRegion::GrainBytes, 196 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT, 197 word_size * HeapWordSize); 198 if (expand_single_region(node_index)) { 199 // Given that expand_single_region() succeeded in expanding the heap, and we 200 // always expand the heap by an amount aligned to the heap 201 // region size, the free list should in theory not be empty. 202 // In either case allocate_free_region() will check for NULL. 203 res = _hrm->allocate_free_region(type, node_index); 204 } else { 205 _expand_heap_after_alloc_failure = false; 206 } 207 } 208 return res; 209 } 210 211 HeapWord* 212 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 213 uint num_regions, 214 size_t word_size) { 215 assert(first_hr != NULL, "pre-condition"); 216 assert(is_humongous(word_size), "word_size should be humongous"); 217 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 218 219 // Index of last region in the series. 220 uint first = first_hr->hrm_index(); 221 uint last = first + num_regions - 1; 222 223 // We need to initialize the region(s) we just discovered. This is 224 // a bit tricky given that it can happen concurrently with 225 // refinement threads refining cards on these regions and 226 // potentially wanting to refine the BOT as they are scanning 227 // those cards (this can happen shortly after a cleanup; see CR 228 // 6991377). So we have to set up the region(s) carefully and in 229 // a specific order. 230 231 // The word size sum of all the regions we will allocate. 232 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 233 assert(word_size <= word_size_sum, "sanity"); 234 235 // The passed in hr will be the "starts humongous" region. The header 236 // of the new object will be placed at the bottom of this region. 237 HeapWord* new_obj = first_hr->bottom(); 238 // This will be the new top of the new object. 239 HeapWord* obj_top = new_obj + word_size; 240 241 // First, we need to zero the header of the space that we will be 242 // allocating. When we update top further down, some refinement 243 // threads might try to scan the region. By zeroing the header we 244 // ensure that any thread that will try to scan the region will 245 // come across the zero klass word and bail out. 246 // 247 // NOTE: It would not have been correct to have used 248 // CollectedHeap::fill_with_object() and make the space look like 249 // an int array. The thread that is doing the allocation will 250 // later update the object header to a potentially different array 251 // type and, for a very short period of time, the klass and length 252 // fields will be inconsistent. This could cause a refinement 253 // thread to calculate the object size incorrectly. 254 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 255 256 // Next, pad out the unused tail of the last region with filler 257 // objects, for improved usage accounting. 258 // How many words we use for filler objects. 259 size_t word_fill_size = word_size_sum - word_size; 260 261 // How many words memory we "waste" which cannot hold a filler object. 262 size_t words_not_fillable = 0; 263 264 if (word_fill_size >= min_fill_size()) { 265 fill_with_objects(obj_top, word_fill_size); 266 } else if (word_fill_size > 0) { 267 // We have space to fill, but we cannot fit an object there. 268 words_not_fillable = word_fill_size; 269 word_fill_size = 0; 270 } 271 272 // We will set up the first region as "starts humongous". This 273 // will also update the BOT covering all the regions to reflect 274 // that there is a single object that starts at the bottom of the 275 // first region. 276 first_hr->set_starts_humongous(obj_top, word_fill_size); 277 _policy->remset_tracker()->update_at_allocate(first_hr); 278 // Then, if there are any, we will set up the "continues 279 // humongous" regions. 280 HeapRegion* hr = NULL; 281 for (uint i = first + 1; i <= last; ++i) { 282 hr = region_at(i); 283 hr->set_continues_humongous(first_hr); 284 _policy->remset_tracker()->update_at_allocate(hr); 285 } 286 287 // Up to this point no concurrent thread would have been able to 288 // do any scanning on any region in this series. All the top 289 // fields still point to bottom, so the intersection between 290 // [bottom,top] and [card_start,card_end] will be empty. Before we 291 // update the top fields, we'll do a storestore to make sure that 292 // no thread sees the update to top before the zeroing of the 293 // object header and the BOT initialization. 294 OrderAccess::storestore(); 295 296 // Now, we will update the top fields of the "continues humongous" 297 // regions except the last one. 298 for (uint i = first; i < last; ++i) { 299 hr = region_at(i); 300 hr->set_top(hr->end()); 301 } 302 303 hr = region_at(last); 304 // If we cannot fit a filler object, we must set top to the end 305 // of the humongous object, otherwise we cannot iterate the heap 306 // and the BOT will not be complete. 307 hr->set_top(hr->end() - words_not_fillable); 308 309 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 310 "obj_top should be in last region"); 311 312 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 313 314 assert(words_not_fillable == 0 || 315 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 316 "Miscalculation in humongous allocation"); 317 318 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 319 320 for (uint i = first; i <= last; ++i) { 321 hr = region_at(i); 322 _humongous_set.add(hr); 323 _hr_printer.alloc(hr); 324 } 325 326 return new_obj; 327 } 328 329 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 330 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 331 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 332 } 333 334 // If could fit into free regions w/o expansion, try. 335 // Otherwise, if can expand, do so. 336 // Otherwise, if using ex regions might help, try with ex given back. 337 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 338 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 339 340 _verifier->verify_region_sets_optional(); 341 342 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 343 344 // Policy: First try to allocate a humongous object in the free list. 345 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions); 346 if (humongous_start == NULL) { 347 // Policy: We could not find enough regions for the humongous object in the 348 // free list. Look through the heap to find a mix of free and uncommitted regions. 349 // If so, expand the heap and allocate the humongous object. 350 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions); 351 if (humongous_start != NULL) { 352 // We managed to find a region by expanding the heap. 353 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B", 354 word_size * HeapWordSize); 355 policy()->record_new_heap_size(num_regions()); 356 } else { 357 // Policy: Potentially trigger a defragmentation GC. 358 } 359 } 360 361 HeapWord* result = NULL; 362 if (humongous_start != NULL) { 363 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size); 364 assert(result != NULL, "it should always return a valid result"); 365 366 // A successful humongous object allocation changes the used space 367 // information of the old generation so we need to recalculate the 368 // sizes and update the jstat counters here. 369 g1mm()->update_sizes(); 370 } 371 372 _verifier->verify_region_sets_optional(); 373 374 return result; 375 } 376 377 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 378 size_t requested_size, 379 size_t* actual_size) { 380 assert_heap_not_locked_and_not_at_safepoint(); 381 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 382 383 return attempt_allocation(min_size, requested_size, actual_size); 384 } 385 386 HeapWord* 387 G1CollectedHeap::mem_allocate(size_t word_size, 388 bool* gc_overhead_limit_was_exceeded) { 389 assert_heap_not_locked_and_not_at_safepoint(); 390 391 if (is_humongous(word_size)) { 392 return attempt_allocation_humongous(word_size); 393 } 394 size_t dummy = 0; 395 return attempt_allocation(word_size, word_size, &dummy); 396 } 397 398 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 399 ResourceMark rm; // For retrieving the thread names in log messages. 400 401 // Make sure you read the note in attempt_allocation_humongous(). 402 403 assert_heap_not_locked_and_not_at_safepoint(); 404 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 405 "be called for humongous allocation requests"); 406 407 // We should only get here after the first-level allocation attempt 408 // (attempt_allocation()) failed to allocate. 409 410 // We will loop until a) we manage to successfully perform the 411 // allocation or b) we successfully schedule a collection which 412 // fails to perform the allocation. b) is the only case when we'll 413 // return NULL. 414 HeapWord* result = NULL; 415 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 416 bool should_try_gc; 417 uint gc_count_before; 418 419 { 420 MutexLocker x(Heap_lock); 421 result = _allocator->attempt_allocation_locked(word_size); 422 if (result != NULL) { 423 return result; 424 } 425 426 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 427 // This is different to when only GCLocker::needs_gc() is set: try to avoid 428 // waiting because the GCLocker is active to not wait too long. 429 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 430 // No need for an ergo message here, can_expand_young_list() does this when 431 // it returns true. 432 result = _allocator->attempt_allocation_force(word_size); 433 if (result != NULL) { 434 return result; 435 } 436 } 437 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 438 // the GCLocker initiated GC has been performed and then retry. This includes 439 // the case when the GC Locker is not active but has not been performed. 440 should_try_gc = !GCLocker::needs_gc(); 441 // Read the GC count while still holding the Heap_lock. 442 gc_count_before = total_collections(); 443 } 444 445 if (should_try_gc) { 446 bool succeeded; 447 result = do_collection_pause(word_size, gc_count_before, &succeeded, 448 GCCause::_g1_inc_collection_pause); 449 if (result != NULL) { 450 assert(succeeded, "only way to get back a non-NULL result"); 451 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 452 Thread::current()->name(), p2i(result)); 453 return result; 454 } 455 456 if (succeeded) { 457 // We successfully scheduled a collection which failed to allocate. No 458 // point in trying to allocate further. We'll just return NULL. 459 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 460 SIZE_FORMAT " words", Thread::current()->name(), word_size); 461 return NULL; 462 } 463 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 464 Thread::current()->name(), word_size); 465 } else { 466 // Failed to schedule a collection. 467 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 468 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 469 SIZE_FORMAT " words", Thread::current()->name(), word_size); 470 return NULL; 471 } 472 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 473 // The GCLocker is either active or the GCLocker initiated 474 // GC has not yet been performed. Stall until it is and 475 // then retry the allocation. 476 GCLocker::stall_until_clear(); 477 gclocker_retry_count += 1; 478 } 479 480 // We can reach here if we were unsuccessful in scheduling a 481 // collection (because another thread beat us to it) or if we were 482 // stalled due to the GC locker. In either can we should retry the 483 // allocation attempt in case another thread successfully 484 // performed a collection and reclaimed enough space. We do the 485 // first attempt (without holding the Heap_lock) here and the 486 // follow-on attempt will be at the start of the next loop 487 // iteration (after taking the Heap_lock). 488 size_t dummy = 0; 489 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 490 if (result != NULL) { 491 return result; 492 } 493 494 // Give a warning if we seem to be looping forever. 495 if ((QueuedAllocationWarningCount > 0) && 496 (try_count % QueuedAllocationWarningCount == 0)) { 497 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 498 Thread::current()->name(), try_count, word_size); 499 } 500 } 501 502 ShouldNotReachHere(); 503 return NULL; 504 } 505 506 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 507 assert_at_safepoint_on_vm_thread(); 508 if (_archive_allocator == NULL) { 509 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 510 } 511 } 512 513 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 514 // Allocations in archive regions cannot be of a size that would be considered 515 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 516 // may be different at archive-restore time. 517 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 518 } 519 520 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 521 assert_at_safepoint_on_vm_thread(); 522 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 523 if (is_archive_alloc_too_large(word_size)) { 524 return NULL; 525 } 526 return _archive_allocator->archive_mem_allocate(word_size); 527 } 528 529 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 530 size_t end_alignment_in_bytes) { 531 assert_at_safepoint_on_vm_thread(); 532 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 533 534 // Call complete_archive to do the real work, filling in the MemRegion 535 // array with the archive regions. 536 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 537 delete _archive_allocator; 538 _archive_allocator = NULL; 539 } 540 541 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 542 assert(ranges != NULL, "MemRegion array NULL"); 543 assert(count != 0, "No MemRegions provided"); 544 MemRegion reserved = _hrm->reserved(); 545 for (size_t i = 0; i < count; i++) { 546 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 547 return false; 548 } 549 } 550 return true; 551 } 552 553 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 554 size_t count, 555 bool open) { 556 assert(!is_init_completed(), "Expect to be called at JVM init time"); 557 assert(ranges != NULL, "MemRegion array NULL"); 558 assert(count != 0, "No MemRegions provided"); 559 MutexLocker x(Heap_lock); 560 561 MemRegion reserved = _hrm->reserved(); 562 HeapWord* prev_last_addr = NULL; 563 HeapRegion* prev_last_region = NULL; 564 565 // Temporarily disable pretouching of heap pages. This interface is used 566 // when mmap'ing archived heap data in, so pre-touching is wasted. 567 FlagSetting fs(AlwaysPreTouch, false); 568 569 // Enable archive object checking used by G1MarkSweep. We have to let it know 570 // about each archive range, so that objects in those ranges aren't marked. 571 G1ArchiveAllocator::enable_archive_object_check(); 572 573 // For each specified MemRegion range, allocate the corresponding G1 574 // regions and mark them as archive regions. We expect the ranges 575 // in ascending starting address order, without overlap. 576 for (size_t i = 0; i < count; i++) { 577 MemRegion curr_range = ranges[i]; 578 HeapWord* start_address = curr_range.start(); 579 size_t word_size = curr_range.word_size(); 580 HeapWord* last_address = curr_range.last(); 581 size_t commits = 0; 582 583 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 584 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 585 p2i(start_address), p2i(last_address)); 586 guarantee(start_address > prev_last_addr, 587 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 588 p2i(start_address), p2i(prev_last_addr)); 589 prev_last_addr = last_address; 590 591 // Check for ranges that start in the same G1 region in which the previous 592 // range ended, and adjust the start address so we don't try to allocate 593 // the same region again. If the current range is entirely within that 594 // region, skip it, just adjusting the recorded top. 595 HeapRegion* start_region = _hrm->addr_to_region(start_address); 596 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 597 start_address = start_region->end(); 598 if (start_address > last_address) { 599 increase_used(word_size * HeapWordSize); 600 start_region->set_top(last_address + 1); 601 continue; 602 } 603 start_region->set_top(start_address); 604 curr_range = MemRegion(start_address, last_address + 1); 605 start_region = _hrm->addr_to_region(start_address); 606 } 607 608 // Perform the actual region allocation, exiting if it fails. 609 // Then note how much new space we have allocated. 610 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 611 return false; 612 } 613 increase_used(word_size * HeapWordSize); 614 if (commits != 0) { 615 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 616 HeapRegion::GrainWords * HeapWordSize * commits); 617 618 } 619 620 // Mark each G1 region touched by the range as archive, add it to 621 // the old set, and set top. 622 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 623 HeapRegion* last_region = _hrm->addr_to_region(last_address); 624 prev_last_region = last_region; 625 626 while (curr_region != NULL) { 627 assert(curr_region->is_empty() && !curr_region->is_pinned(), 628 "Region already in use (index %u)", curr_region->hrm_index()); 629 if (open) { 630 curr_region->set_open_archive(); 631 } else { 632 curr_region->set_closed_archive(); 633 } 634 _hr_printer.alloc(curr_region); 635 _archive_set.add(curr_region); 636 HeapWord* top; 637 HeapRegion* next_region; 638 if (curr_region != last_region) { 639 top = curr_region->end(); 640 next_region = _hrm->next_region_in_heap(curr_region); 641 } else { 642 top = last_address + 1; 643 next_region = NULL; 644 } 645 curr_region->set_top(top); 646 curr_region = next_region; 647 } 648 649 // Notify mark-sweep of the archive 650 G1ArchiveAllocator::set_range_archive(curr_range, open); 651 } 652 return true; 653 } 654 655 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 656 assert(!is_init_completed(), "Expect to be called at JVM init time"); 657 assert(ranges != NULL, "MemRegion array NULL"); 658 assert(count != 0, "No MemRegions provided"); 659 MemRegion reserved = _hrm->reserved(); 660 HeapWord *prev_last_addr = NULL; 661 HeapRegion* prev_last_region = NULL; 662 663 // For each MemRegion, create filler objects, if needed, in the G1 regions 664 // that contain the address range. The address range actually within the 665 // MemRegion will not be modified. That is assumed to have been initialized 666 // elsewhere, probably via an mmap of archived heap data. 667 MutexLocker x(Heap_lock); 668 for (size_t i = 0; i < count; i++) { 669 HeapWord* start_address = ranges[i].start(); 670 HeapWord* last_address = ranges[i].last(); 671 672 assert(reserved.contains(start_address) && reserved.contains(last_address), 673 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 674 p2i(start_address), p2i(last_address)); 675 assert(start_address > prev_last_addr, 676 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 677 p2i(start_address), p2i(prev_last_addr)); 678 679 HeapRegion* start_region = _hrm->addr_to_region(start_address); 680 HeapRegion* last_region = _hrm->addr_to_region(last_address); 681 HeapWord* bottom_address = start_region->bottom(); 682 683 // Check for a range beginning in the same region in which the 684 // previous one ended. 685 if (start_region == prev_last_region) { 686 bottom_address = prev_last_addr + 1; 687 } 688 689 // Verify that the regions were all marked as archive regions by 690 // alloc_archive_regions. 691 HeapRegion* curr_region = start_region; 692 while (curr_region != NULL) { 693 guarantee(curr_region->is_archive(), 694 "Expected archive region at index %u", curr_region->hrm_index()); 695 if (curr_region != last_region) { 696 curr_region = _hrm->next_region_in_heap(curr_region); 697 } else { 698 curr_region = NULL; 699 } 700 } 701 702 prev_last_addr = last_address; 703 prev_last_region = last_region; 704 705 // Fill the memory below the allocated range with dummy object(s), 706 // if the region bottom does not match the range start, or if the previous 707 // range ended within the same G1 region, and there is a gap. 708 if (start_address != bottom_address) { 709 size_t fill_size = pointer_delta(start_address, bottom_address); 710 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 711 increase_used(fill_size * HeapWordSize); 712 } 713 } 714 } 715 716 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 717 size_t desired_word_size, 718 size_t* actual_word_size) { 719 assert_heap_not_locked_and_not_at_safepoint(); 720 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 721 "be called for humongous allocation requests"); 722 723 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 724 725 if (result == NULL) { 726 *actual_word_size = desired_word_size; 727 result = attempt_allocation_slow(desired_word_size); 728 } 729 730 assert_heap_not_locked(); 731 if (result != NULL) { 732 assert(*actual_word_size != 0, "Actual size must have been set here"); 733 dirty_young_block(result, *actual_word_size); 734 } else { 735 *actual_word_size = 0; 736 } 737 738 return result; 739 } 740 741 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 742 assert(!is_init_completed(), "Expect to be called at JVM init time"); 743 assert(ranges != NULL, "MemRegion array NULL"); 744 assert(count != 0, "No MemRegions provided"); 745 MemRegion reserved = _hrm->reserved(); 746 HeapWord* prev_last_addr = NULL; 747 HeapRegion* prev_last_region = NULL; 748 size_t size_used = 0; 749 size_t uncommitted_regions = 0; 750 751 // For each Memregion, free the G1 regions that constitute it, and 752 // notify mark-sweep that the range is no longer to be considered 'archive.' 753 MutexLocker x(Heap_lock); 754 for (size_t i = 0; i < count; i++) { 755 HeapWord* start_address = ranges[i].start(); 756 HeapWord* last_address = ranges[i].last(); 757 758 assert(reserved.contains(start_address) && reserved.contains(last_address), 759 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 760 p2i(start_address), p2i(last_address)); 761 assert(start_address > prev_last_addr, 762 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 763 p2i(start_address), p2i(prev_last_addr)); 764 size_used += ranges[i].byte_size(); 765 prev_last_addr = last_address; 766 767 HeapRegion* start_region = _hrm->addr_to_region(start_address); 768 HeapRegion* last_region = _hrm->addr_to_region(last_address); 769 770 // Check for ranges that start in the same G1 region in which the previous 771 // range ended, and adjust the start address so we don't try to free 772 // the same region again. If the current range is entirely within that 773 // region, skip it. 774 if (start_region == prev_last_region) { 775 start_address = start_region->end(); 776 if (start_address > last_address) { 777 continue; 778 } 779 start_region = _hrm->addr_to_region(start_address); 780 } 781 prev_last_region = last_region; 782 783 // After verifying that each region was marked as an archive region by 784 // alloc_archive_regions, set it free and empty and uncommit it. 785 HeapRegion* curr_region = start_region; 786 while (curr_region != NULL) { 787 guarantee(curr_region->is_archive(), 788 "Expected archive region at index %u", curr_region->hrm_index()); 789 uint curr_index = curr_region->hrm_index(); 790 _archive_set.remove(curr_region); 791 curr_region->set_free(); 792 curr_region->set_top(curr_region->bottom()); 793 if (curr_region != last_region) { 794 curr_region = _hrm->next_region_in_heap(curr_region); 795 } else { 796 curr_region = NULL; 797 } 798 _hrm->shrink_at(curr_index, 1); 799 uncommitted_regions++; 800 } 801 802 // Notify mark-sweep that this is no longer an archive range. 803 G1ArchiveAllocator::clear_range_archive(ranges[i]); 804 } 805 806 if (uncommitted_regions != 0) { 807 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 808 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 809 } 810 decrease_used(size_used); 811 } 812 813 oop G1CollectedHeap::materialize_archived_object(oop obj) { 814 assert(obj != NULL, "archived obj is NULL"); 815 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 816 817 // Loading an archived object makes it strongly reachable. If it is 818 // loaded during concurrent marking, it must be enqueued to the SATB 819 // queue, shading the previously white object gray. 820 G1BarrierSet::enqueue(obj); 821 822 return obj; 823 } 824 825 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 826 ResourceMark rm; // For retrieving the thread names in log messages. 827 828 // The structure of this method has a lot of similarities to 829 // attempt_allocation_slow(). The reason these two were not merged 830 // into a single one is that such a method would require several "if 831 // allocation is not humongous do this, otherwise do that" 832 // conditional paths which would obscure its flow. In fact, an early 833 // version of this code did use a unified method which was harder to 834 // follow and, as a result, it had subtle bugs that were hard to 835 // track down. So keeping these two methods separate allows each to 836 // be more readable. It will be good to keep these two in sync as 837 // much as possible. 838 839 assert_heap_not_locked_and_not_at_safepoint(); 840 assert(is_humongous(word_size), "attempt_allocation_humongous() " 841 "should only be called for humongous allocations"); 842 843 // Humongous objects can exhaust the heap quickly, so we should check if we 844 // need to start a marking cycle at each humongous object allocation. We do 845 // the check before we do the actual allocation. The reason for doing it 846 // before the allocation is that we avoid having to keep track of the newly 847 // allocated memory while we do a GC. 848 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 849 word_size)) { 850 collect(GCCause::_g1_humongous_allocation); 851 } 852 853 // We will loop until a) we manage to successfully perform the 854 // allocation or b) we successfully schedule a collection which 855 // fails to perform the allocation. b) is the only case when we'll 856 // return NULL. 857 HeapWord* result = NULL; 858 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 859 bool should_try_gc; 860 uint gc_count_before; 861 862 863 { 864 MutexLocker x(Heap_lock); 865 866 // Given that humongous objects are not allocated in young 867 // regions, we'll first try to do the allocation without doing a 868 // collection hoping that there's enough space in the heap. 869 result = humongous_obj_allocate(word_size); 870 if (result != NULL) { 871 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 872 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 873 return result; 874 } 875 876 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 877 // the GCLocker initiated GC has been performed and then retry. This includes 878 // the case when the GC Locker is not active but has not been performed. 879 should_try_gc = !GCLocker::needs_gc(); 880 // Read the GC count while still holding the Heap_lock. 881 gc_count_before = total_collections(); 882 } 883 884 if (should_try_gc) { 885 bool succeeded; 886 result = do_collection_pause(word_size, gc_count_before, &succeeded, 887 GCCause::_g1_humongous_allocation); 888 if (result != NULL) { 889 assert(succeeded, "only way to get back a non-NULL result"); 890 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 891 Thread::current()->name(), p2i(result)); 892 return result; 893 } 894 895 if (succeeded) { 896 // We successfully scheduled a collection which failed to allocate. No 897 // point in trying to allocate further. We'll just return NULL. 898 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 899 SIZE_FORMAT " words", Thread::current()->name(), word_size); 900 return NULL; 901 } 902 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 903 Thread::current()->name(), word_size); 904 } else { 905 // Failed to schedule a collection. 906 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 907 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 908 SIZE_FORMAT " words", Thread::current()->name(), word_size); 909 return NULL; 910 } 911 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 912 // The GCLocker is either active or the GCLocker initiated 913 // GC has not yet been performed. Stall until it is and 914 // then retry the allocation. 915 GCLocker::stall_until_clear(); 916 gclocker_retry_count += 1; 917 } 918 919 920 // We can reach here if we were unsuccessful in scheduling a 921 // collection (because another thread beat us to it) or if we were 922 // stalled due to the GC locker. In either can we should retry the 923 // allocation attempt in case another thread successfully 924 // performed a collection and reclaimed enough space. 925 // Humongous object allocation always needs a lock, so we wait for the retry 926 // in the next iteration of the loop, unlike for the regular iteration case. 927 // Give a warning if we seem to be looping forever. 928 929 if ((QueuedAllocationWarningCount > 0) && 930 (try_count % QueuedAllocationWarningCount == 0)) { 931 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 932 Thread::current()->name(), try_count, word_size); 933 } 934 } 935 936 ShouldNotReachHere(); 937 return NULL; 938 } 939 940 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 941 bool expect_null_mutator_alloc_region) { 942 assert_at_safepoint_on_vm_thread(); 943 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 944 "the current alloc region was unexpectedly found to be non-NULL"); 945 946 if (!is_humongous(word_size)) { 947 return _allocator->attempt_allocation_locked(word_size); 948 } else { 949 HeapWord* result = humongous_obj_allocate(word_size); 950 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 951 collector_state()->set_initiate_conc_mark_if_possible(true); 952 } 953 return result; 954 } 955 956 ShouldNotReachHere(); 957 } 958 959 class PostCompactionPrinterClosure: public HeapRegionClosure { 960 private: 961 G1HRPrinter* _hr_printer; 962 public: 963 bool do_heap_region(HeapRegion* hr) { 964 assert(!hr->is_young(), "not expecting to find young regions"); 965 _hr_printer->post_compaction(hr); 966 return false; 967 } 968 969 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 970 : _hr_printer(hr_printer) { } 971 }; 972 973 void G1CollectedHeap::print_hrm_post_compaction() { 974 if (_hr_printer.is_active()) { 975 PostCompactionPrinterClosure cl(hr_printer()); 976 heap_region_iterate(&cl); 977 } 978 } 979 980 void G1CollectedHeap::abort_concurrent_cycle() { 981 // If we start the compaction before the CM threads finish 982 // scanning the root regions we might trip them over as we'll 983 // be moving objects / updating references. So let's wait until 984 // they are done. By telling them to abort, they should complete 985 // early. 986 _cm->root_regions()->abort(); 987 _cm->root_regions()->wait_until_scan_finished(); 988 989 // Disable discovery and empty the discovered lists 990 // for the CM ref processor. 991 _ref_processor_cm->disable_discovery(); 992 _ref_processor_cm->abandon_partial_discovery(); 993 _ref_processor_cm->verify_no_references_recorded(); 994 995 // Abandon current iterations of concurrent marking and concurrent 996 // refinement, if any are in progress. 997 concurrent_mark()->concurrent_cycle_abort(); 998 } 999 1000 void G1CollectedHeap::prepare_heap_for_full_collection() { 1001 // Make sure we'll choose a new allocation region afterwards. 1002 _allocator->release_mutator_alloc_regions(); 1003 _allocator->abandon_gc_alloc_regions(); 1004 1005 // We may have added regions to the current incremental collection 1006 // set between the last GC or pause and now. We need to clear the 1007 // incremental collection set and then start rebuilding it afresh 1008 // after this full GC. 1009 abandon_collection_set(collection_set()); 1010 1011 tear_down_region_sets(false /* free_list_only */); 1012 1013 hrm()->prepare_for_full_collection_start(); 1014 } 1015 1016 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1017 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1018 assert_used_and_recalculate_used_equal(this); 1019 _verifier->verify_region_sets_optional(); 1020 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1021 _verifier->check_bitmaps("Full GC Start"); 1022 } 1023 1024 void G1CollectedHeap::prepare_heap_for_mutators() { 1025 hrm()->prepare_for_full_collection_end(); 1026 1027 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1028 ClassLoaderDataGraph::purge(); 1029 MetaspaceUtils::verify_metrics(); 1030 1031 // Prepare heap for normal collections. 1032 assert(num_free_regions() == 0, "we should not have added any free regions"); 1033 rebuild_region_sets(false /* free_list_only */); 1034 abort_refinement(); 1035 resize_heap_if_necessary(); 1036 1037 // Rebuild the strong code root lists for each region 1038 rebuild_strong_code_roots(); 1039 1040 // Purge code root memory 1041 purge_code_root_memory(); 1042 1043 // Start a new incremental collection set for the next pause 1044 start_new_collection_set(); 1045 1046 _allocator->init_mutator_alloc_regions(); 1047 1048 // Post collection state updates. 1049 MetaspaceGC::compute_new_size(); 1050 } 1051 1052 void G1CollectedHeap::abort_refinement() { 1053 if (_hot_card_cache->use_cache()) { 1054 _hot_card_cache->reset_hot_cache(); 1055 } 1056 1057 // Discard all remembered set updates and reset refinement statistics. 1058 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1059 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0, 1060 "DCQS should be empty"); 1061 concurrent_refine()->get_and_reset_refinement_stats(); 1062 } 1063 1064 void G1CollectedHeap::verify_after_full_collection() { 1065 _hrm->verify_optional(); 1066 _verifier->verify_region_sets_optional(); 1067 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1068 // Clear the previous marking bitmap, if needed for bitmap verification. 1069 // Note we cannot do this when we clear the next marking bitmap in 1070 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1071 // objects marked during a full GC against the previous bitmap. 1072 // But we need to clear it before calling check_bitmaps below since 1073 // the full GC has compacted objects and updated TAMS but not updated 1074 // the prev bitmap. 1075 if (G1VerifyBitmaps) { 1076 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification"); 1077 _cm->clear_prev_bitmap(workers()); 1078 } 1079 // This call implicitly verifies that the next bitmap is clear after Full GC. 1080 _verifier->check_bitmaps("Full GC End"); 1081 1082 // At this point there should be no regions in the 1083 // entire heap tagged as young. 1084 assert(check_young_list_empty(), "young list should be empty at this point"); 1085 1086 // Note: since we've just done a full GC, concurrent 1087 // marking is no longer active. Therefore we need not 1088 // re-enable reference discovery for the CM ref processor. 1089 // That will be done at the start of the next marking cycle. 1090 // We also know that the STW processor should no longer 1091 // discover any new references. 1092 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1093 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1094 _ref_processor_stw->verify_no_references_recorded(); 1095 _ref_processor_cm->verify_no_references_recorded(); 1096 } 1097 1098 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1099 // Post collection logging. 1100 // We should do this after we potentially resize the heap so 1101 // that all the COMMIT / UNCOMMIT events are generated before 1102 // the compaction events. 1103 print_hrm_post_compaction(); 1104 heap_transition->print(); 1105 print_heap_after_gc(); 1106 print_heap_regions(); 1107 } 1108 1109 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1110 bool clear_all_soft_refs) { 1111 assert_at_safepoint_on_vm_thread(); 1112 1113 if (GCLocker::check_active_before_gc()) { 1114 // Full GC was not completed. 1115 return false; 1116 } 1117 1118 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1119 soft_ref_policy()->should_clear_all_soft_refs(); 1120 1121 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1122 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1123 1124 collector.prepare_collection(); 1125 collector.collect(); 1126 collector.complete_collection(); 1127 1128 // Full collection was successfully completed. 1129 return true; 1130 } 1131 1132 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1133 // Currently, there is no facility in the do_full_collection(bool) API to notify 1134 // the caller that the collection did not succeed (e.g., because it was locked 1135 // out by the GC locker). So, right now, we'll ignore the return value. 1136 bool dummy = do_full_collection(true, /* explicit_gc */ 1137 clear_all_soft_refs); 1138 } 1139 1140 void G1CollectedHeap::resize_heap_if_necessary() { 1141 assert_at_safepoint_on_vm_thread(); 1142 1143 // Capacity, free and used after the GC counted as full regions to 1144 // include the waste in the following calculations. 1145 const size_t capacity_after_gc = capacity(); 1146 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1147 1148 // This is enforced in arguments.cpp. 1149 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1150 "otherwise the code below doesn't make sense"); 1151 1152 // We don't have floating point command-line arguments 1153 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1154 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1155 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1156 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1157 1158 // We have to be careful here as these two calculations can overflow 1159 // 32-bit size_t's. 1160 double used_after_gc_d = (double) used_after_gc; 1161 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1162 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1163 1164 // Let's make sure that they are both under the max heap size, which 1165 // by default will make them fit into a size_t. 1166 double desired_capacity_upper_bound = (double) MaxHeapSize; 1167 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1168 desired_capacity_upper_bound); 1169 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1170 desired_capacity_upper_bound); 1171 1172 // We can now safely turn them into size_t's. 1173 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1174 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1175 1176 // This assert only makes sense here, before we adjust them 1177 // with respect to the min and max heap size. 1178 assert(minimum_desired_capacity <= maximum_desired_capacity, 1179 "minimum_desired_capacity = " SIZE_FORMAT ", " 1180 "maximum_desired_capacity = " SIZE_FORMAT, 1181 minimum_desired_capacity, maximum_desired_capacity); 1182 1183 // Should not be greater than the heap max size. No need to adjust 1184 // it with respect to the heap min size as it's a lower bound (i.e., 1185 // we'll try to make the capacity larger than it, not smaller). 1186 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize); 1187 // Should not be less than the heap min size. No need to adjust it 1188 // with respect to the heap max size as it's an upper bound (i.e., 1189 // we'll try to make the capacity smaller than it, not greater). 1190 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize); 1191 1192 if (capacity_after_gc < minimum_desired_capacity) { 1193 // Don't expand unless it's significant 1194 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1195 1196 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1197 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1198 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1199 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1200 1201 expand(expand_bytes, _workers); 1202 1203 // No expansion, now see if we want to shrink 1204 } else if (capacity_after_gc > maximum_desired_capacity) { 1205 // Capacity too large, compute shrinking size 1206 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1207 1208 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1209 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1210 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1211 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1212 1213 shrink(shrink_bytes); 1214 } 1215 } 1216 1217 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1218 bool do_gc, 1219 bool clear_all_soft_refs, 1220 bool expect_null_mutator_alloc_region, 1221 bool* gc_succeeded) { 1222 *gc_succeeded = true; 1223 // Let's attempt the allocation first. 1224 HeapWord* result = 1225 attempt_allocation_at_safepoint(word_size, 1226 expect_null_mutator_alloc_region); 1227 if (result != NULL) { 1228 return result; 1229 } 1230 1231 // In a G1 heap, we're supposed to keep allocation from failing by 1232 // incremental pauses. Therefore, at least for now, we'll favor 1233 // expansion over collection. (This might change in the future if we can 1234 // do something smarter than full collection to satisfy a failed alloc.) 1235 result = expand_and_allocate(word_size); 1236 if (result != NULL) { 1237 return result; 1238 } 1239 1240 if (do_gc) { 1241 // Expansion didn't work, we'll try to do a Full GC. 1242 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1243 clear_all_soft_refs); 1244 } 1245 1246 return NULL; 1247 } 1248 1249 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1250 bool* succeeded) { 1251 assert_at_safepoint_on_vm_thread(); 1252 1253 // Attempts to allocate followed by Full GC. 1254 HeapWord* result = 1255 satisfy_failed_allocation_helper(word_size, 1256 true, /* do_gc */ 1257 false, /* clear_all_soft_refs */ 1258 false, /* expect_null_mutator_alloc_region */ 1259 succeeded); 1260 1261 if (result != NULL || !*succeeded) { 1262 return result; 1263 } 1264 1265 // Attempts to allocate followed by Full GC that will collect all soft references. 1266 result = satisfy_failed_allocation_helper(word_size, 1267 true, /* do_gc */ 1268 true, /* clear_all_soft_refs */ 1269 true, /* expect_null_mutator_alloc_region */ 1270 succeeded); 1271 1272 if (result != NULL || !*succeeded) { 1273 return result; 1274 } 1275 1276 // Attempts to allocate, no GC 1277 result = satisfy_failed_allocation_helper(word_size, 1278 false, /* do_gc */ 1279 false, /* clear_all_soft_refs */ 1280 true, /* expect_null_mutator_alloc_region */ 1281 succeeded); 1282 1283 if (result != NULL) { 1284 return result; 1285 } 1286 1287 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1288 "Flag should have been handled and cleared prior to this point"); 1289 1290 // What else? We might try synchronous finalization later. If the total 1291 // space available is large enough for the allocation, then a more 1292 // complete compaction phase than we've tried so far might be 1293 // appropriate. 1294 return NULL; 1295 } 1296 1297 // Attempting to expand the heap sufficiently 1298 // to support an allocation of the given "word_size". If 1299 // successful, perform the allocation and return the address of the 1300 // allocated block, or else "NULL". 1301 1302 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1303 assert_at_safepoint_on_vm_thread(); 1304 1305 _verifier->verify_region_sets_optional(); 1306 1307 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1308 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1309 word_size * HeapWordSize); 1310 1311 1312 if (expand(expand_bytes, _workers)) { 1313 _hrm->verify_optional(); 1314 _verifier->verify_region_sets_optional(); 1315 return attempt_allocation_at_safepoint(word_size, 1316 false /* expect_null_mutator_alloc_region */); 1317 } 1318 return NULL; 1319 } 1320 1321 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1322 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1323 aligned_expand_bytes = align_up(aligned_expand_bytes, 1324 HeapRegion::GrainBytes); 1325 1326 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1327 expand_bytes, aligned_expand_bytes); 1328 1329 if (is_maximal_no_gc()) { 1330 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1331 return false; 1332 } 1333 1334 double expand_heap_start_time_sec = os::elapsedTime(); 1335 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1336 assert(regions_to_expand > 0, "Must expand by at least one region"); 1337 1338 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1339 if (expand_time_ms != NULL) { 1340 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1341 } 1342 1343 if (expanded_by > 0) { 1344 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1345 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1346 policy()->record_new_heap_size(num_regions()); 1347 } else { 1348 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1349 1350 // The expansion of the virtual storage space was unsuccessful. 1351 // Let's see if it was because we ran out of swap. 1352 if (G1ExitOnExpansionFailure && 1353 _hrm->available() >= regions_to_expand) { 1354 // We had head room... 1355 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1356 } 1357 } 1358 return regions_to_expand > 0; 1359 } 1360 1361 bool G1CollectedHeap::expand_single_region(uint node_index) { 1362 uint expanded_by = _hrm->expand_on_preferred_node(node_index); 1363 1364 if (expanded_by == 0) { 1365 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available()); 1366 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1367 return false; 1368 } 1369 1370 policy()->record_new_heap_size(num_regions()); 1371 return true; 1372 } 1373 1374 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1375 size_t aligned_shrink_bytes = 1376 ReservedSpace::page_align_size_down(shrink_bytes); 1377 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1378 HeapRegion::GrainBytes); 1379 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1380 1381 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1382 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1383 1384 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", 1385 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1386 if (num_regions_removed > 0) { 1387 policy()->record_new_heap_size(num_regions()); 1388 } else { 1389 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1390 } 1391 } 1392 1393 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1394 _verifier->verify_region_sets_optional(); 1395 1396 // We should only reach here at the end of a Full GC or during Remark which 1397 // means we should not not be holding to any GC alloc regions. The method 1398 // below will make sure of that and do any remaining clean up. 1399 _allocator->abandon_gc_alloc_regions(); 1400 1401 // Instead of tearing down / rebuilding the free lists here, we 1402 // could instead use the remove_all_pending() method on free_list to 1403 // remove only the ones that we need to remove. 1404 tear_down_region_sets(true /* free_list_only */); 1405 shrink_helper(shrink_bytes); 1406 rebuild_region_sets(true /* free_list_only */); 1407 1408 _hrm->verify_optional(); 1409 _verifier->verify_region_sets_optional(); 1410 } 1411 1412 class OldRegionSetChecker : public HeapRegionSetChecker { 1413 public: 1414 void check_mt_safety() { 1415 // Master Old Set MT safety protocol: 1416 // (a) If we're at a safepoint, operations on the master old set 1417 // should be invoked: 1418 // - by the VM thread (which will serialize them), or 1419 // - by the GC workers while holding the FreeList_lock, if we're 1420 // at a safepoint for an evacuation pause (this lock is taken 1421 // anyway when an GC alloc region is retired so that a new one 1422 // is allocated from the free list), or 1423 // - by the GC workers while holding the OldSets_lock, if we're at a 1424 // safepoint for a cleanup pause. 1425 // (b) If we're not at a safepoint, operations on the master old set 1426 // should be invoked while holding the Heap_lock. 1427 1428 if (SafepointSynchronize::is_at_safepoint()) { 1429 guarantee(Thread::current()->is_VM_thread() || 1430 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1431 "master old set MT safety protocol at a safepoint"); 1432 } else { 1433 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1434 } 1435 } 1436 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1437 const char* get_description() { return "Old Regions"; } 1438 }; 1439 1440 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1441 public: 1442 void check_mt_safety() { 1443 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1444 "May only change archive regions during initialization or safepoint."); 1445 } 1446 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1447 const char* get_description() { return "Archive Regions"; } 1448 }; 1449 1450 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1451 public: 1452 void check_mt_safety() { 1453 // Humongous Set MT safety protocol: 1454 // (a) If we're at a safepoint, operations on the master humongous 1455 // set should be invoked by either the VM thread (which will 1456 // serialize them) or by the GC workers while holding the 1457 // OldSets_lock. 1458 // (b) If we're not at a safepoint, operations on the master 1459 // humongous set should be invoked while holding the Heap_lock. 1460 1461 if (SafepointSynchronize::is_at_safepoint()) { 1462 guarantee(Thread::current()->is_VM_thread() || 1463 OldSets_lock->owned_by_self(), 1464 "master humongous set MT safety protocol at a safepoint"); 1465 } else { 1466 guarantee(Heap_lock->owned_by_self(), 1467 "master humongous set MT safety protocol outside a safepoint"); 1468 } 1469 } 1470 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1471 const char* get_description() { return "Humongous Regions"; } 1472 }; 1473 1474 G1CollectedHeap::G1CollectedHeap() : 1475 CollectedHeap(), 1476 _young_gen_sampling_thread(NULL), 1477 _workers(NULL), 1478 _card_table(NULL), 1479 _soft_ref_policy(), 1480 _old_set("Old Region Set", new OldRegionSetChecker()), 1481 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1482 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1483 _bot(NULL), 1484 _listener(), 1485 _numa(G1NUMA::create()), 1486 _hrm(NULL), 1487 _allocator(NULL), 1488 _verifier(NULL), 1489 _summary_bytes_used(0), 1490 _bytes_used_during_gc(0), 1491 _archive_allocator(NULL), 1492 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1493 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1494 _expand_heap_after_alloc_failure(true), 1495 _g1mm(NULL), 1496 _humongous_reclaim_candidates(), 1497 _has_humongous_reclaim_candidates(false), 1498 _hr_printer(), 1499 _collector_state(), 1500 _old_marking_cycles_started(0), 1501 _old_marking_cycles_completed(0), 1502 _eden(), 1503 _survivor(), 1504 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1505 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1506 _policy(G1Policy::create_policy(_gc_timer_stw)), 1507 _heap_sizing_policy(NULL), 1508 _collection_set(this, _policy), 1509 _hot_card_cache(NULL), 1510 _rem_set(NULL), 1511 _cm(NULL), 1512 _cm_thread(NULL), 1513 _cr(NULL), 1514 _task_queues(NULL), 1515 _evacuation_failed(false), 1516 _evacuation_failed_info_array(NULL), 1517 _preserved_marks_set(true /* in_c_heap */), 1518 #ifndef PRODUCT 1519 _evacuation_failure_alot_for_current_gc(false), 1520 _evacuation_failure_alot_gc_number(0), 1521 _evacuation_failure_alot_count(0), 1522 #endif 1523 _ref_processor_stw(NULL), 1524 _is_alive_closure_stw(this), 1525 _is_subject_to_discovery_stw(this), 1526 _ref_processor_cm(NULL), 1527 _is_alive_closure_cm(this), 1528 _is_subject_to_discovery_cm(this), 1529 _region_attr() { 1530 1531 _verifier = new G1HeapVerifier(this); 1532 1533 _allocator = new G1Allocator(this); 1534 1535 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1536 1537 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1538 1539 // Override the default _filler_array_max_size so that no humongous filler 1540 // objects are created. 1541 _filler_array_max_size = _humongous_object_threshold_in_words; 1542 1543 uint n_queues = ParallelGCThreads; 1544 _task_queues = new RefToScanQueueSet(n_queues); 1545 1546 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1547 1548 for (uint i = 0; i < n_queues; i++) { 1549 RefToScanQueue* q = new RefToScanQueue(); 1550 q->initialize(); 1551 _task_queues->register_queue(i, q); 1552 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1553 } 1554 1555 // Initialize the G1EvacuationFailureALot counters and flags. 1556 NOT_PRODUCT(reset_evacuation_should_fail();) 1557 _gc_tracer_stw->initialize(); 1558 1559 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1560 } 1561 1562 static size_t actual_reserved_page_size(ReservedSpace rs) { 1563 size_t page_size = os::vm_page_size(); 1564 if (UseLargePages) { 1565 // There are two ways to manage large page memory. 1566 // 1. OS supports committing large page memory. 1567 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1568 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1569 // we reserved memory without large page. 1570 if (os::can_commit_large_page_memory() || rs.special()) { 1571 // An alignment at ReservedSpace comes from preferred page size or 1572 // heap alignment, and if the alignment came from heap alignment, it could be 1573 // larger than large pages size. So need to cap with the large page size. 1574 page_size = MIN2(rs.alignment(), os::large_page_size()); 1575 } 1576 } 1577 1578 return page_size; 1579 } 1580 1581 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1582 size_t size, 1583 size_t translation_factor) { 1584 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1585 // Allocate a new reserved space, preferring to use large pages. 1586 ReservedSpace rs(size, preferred_page_size); 1587 size_t page_size = actual_reserved_page_size(rs); 1588 G1RegionToSpaceMapper* result = 1589 G1RegionToSpaceMapper::create_mapper(rs, 1590 size, 1591 page_size, 1592 HeapRegion::GrainBytes, 1593 translation_factor, 1594 mtGC); 1595 1596 os::trace_page_sizes_for_requested_size(description, 1597 size, 1598 preferred_page_size, 1599 page_size, 1600 rs.base(), 1601 rs.size()); 1602 1603 return result; 1604 } 1605 1606 jint G1CollectedHeap::initialize_concurrent_refinement() { 1607 jint ecode = JNI_OK; 1608 _cr = G1ConcurrentRefine::create(&ecode); 1609 return ecode; 1610 } 1611 1612 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1613 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1614 if (_young_gen_sampling_thread->osthread() == NULL) { 1615 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1616 return JNI_ENOMEM; 1617 } 1618 return JNI_OK; 1619 } 1620 1621 jint G1CollectedHeap::initialize() { 1622 1623 // Necessary to satisfy locking discipline assertions. 1624 1625 MutexLocker x(Heap_lock); 1626 1627 // While there are no constraints in the GC code that HeapWordSize 1628 // be any particular value, there are multiple other areas in the 1629 // system which believe this to be true (e.g. oop->object_size in some 1630 // cases incorrectly returns the size in wordSize units rather than 1631 // HeapWordSize). 1632 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1633 1634 size_t init_byte_size = InitialHeapSize; 1635 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes(); 1636 1637 // Ensure that the sizes are properly aligned. 1638 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1639 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1640 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap"); 1641 1642 // Reserve the maximum. 1643 1644 // When compressed oops are enabled, the preferred heap base 1645 // is calculated by subtracting the requested size from the 1646 // 32Gb boundary and using the result as the base address for 1647 // heap reservation. If the requested size is not aligned to 1648 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1649 // into the ReservedHeapSpace constructor) then the actual 1650 // base of the reserved heap may end up differing from the 1651 // address that was requested (i.e. the preferred heap base). 1652 // If this happens then we could end up using a non-optimal 1653 // compressed oops mode. 1654 1655 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size, 1656 HeapAlignment); 1657 1658 initialize_reserved_region(heap_rs); 1659 1660 // Create the barrier set for the entire reserved region. 1661 G1CardTable* ct = new G1CardTable(heap_rs.region()); 1662 ct->initialize(); 1663 G1BarrierSet* bs = new G1BarrierSet(ct); 1664 bs->initialize(); 1665 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1666 BarrierSet::set_barrier_set(bs); 1667 _card_table = ct; 1668 1669 { 1670 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set(); 1671 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold); 1672 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent); 1673 } 1674 1675 // Create the hot card cache. 1676 _hot_card_cache = new G1HotCardCache(this); 1677 1678 // Carve out the G1 part of the heap. 1679 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size); 1680 size_t page_size = actual_reserved_page_size(heap_rs); 1681 G1RegionToSpaceMapper* heap_storage = 1682 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1683 g1_rs.size(), 1684 page_size, 1685 HeapRegion::GrainBytes, 1686 1, 1687 mtJavaHeap); 1688 if(heap_storage == NULL) { 1689 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1690 return JNI_ERR; 1691 } 1692 1693 os::trace_page_sizes("Heap", 1694 MinHeapSize, 1695 reserved_byte_size, 1696 page_size, 1697 heap_rs.base(), 1698 heap_rs.size()); 1699 heap_storage->set_mapping_changed_listener(&_listener); 1700 1701 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1702 G1RegionToSpaceMapper* bot_storage = 1703 create_aux_memory_mapper("Block Offset Table", 1704 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1705 G1BlockOffsetTable::heap_map_factor()); 1706 1707 G1RegionToSpaceMapper* cardtable_storage = 1708 create_aux_memory_mapper("Card Table", 1709 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1710 G1CardTable::heap_map_factor()); 1711 1712 G1RegionToSpaceMapper* card_counts_storage = 1713 create_aux_memory_mapper("Card Counts Table", 1714 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1715 G1CardCounts::heap_map_factor()); 1716 1717 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1718 G1RegionToSpaceMapper* prev_bitmap_storage = 1719 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1720 G1RegionToSpaceMapper* next_bitmap_storage = 1721 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1722 1723 _hrm = HeapRegionManager::create_manager(this); 1724 1725 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1726 _card_table->initialize(cardtable_storage); 1727 1728 // Do later initialization work for concurrent refinement. 1729 _hot_card_cache->initialize(card_counts_storage); 1730 1731 // 6843694 - ensure that the maximum region index can fit 1732 // in the remembered set structures. 1733 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1734 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1735 1736 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1737 // start within the first card. 1738 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1739 // Also create a G1 rem set. 1740 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1741 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1742 1743 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1744 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1745 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1746 "too many cards per region"); 1747 1748 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1749 1750 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1751 1752 { 1753 HeapWord* start = _hrm->reserved().start(); 1754 HeapWord* end = _hrm->reserved().end(); 1755 size_t granularity = HeapRegion::GrainBytes; 1756 1757 _region_attr.initialize(start, end, granularity); 1758 _humongous_reclaim_candidates.initialize(start, end, granularity); 1759 } 1760 1761 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1762 true /* are_GC_task_threads */, 1763 false /* are_ConcurrentGC_threads */); 1764 if (_workers == NULL) { 1765 return JNI_ENOMEM; 1766 } 1767 _workers->initialize_workers(); 1768 1769 _numa->set_region_info(HeapRegion::GrainBytes, page_size); 1770 1771 // Create the G1ConcurrentMark data structure and thread. 1772 // (Must do this late, so that "max_regions" is defined.) 1773 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1774 _cm_thread = _cm->cm_thread(); 1775 1776 // Now expand into the initial heap size. 1777 if (!expand(init_byte_size, _workers)) { 1778 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1779 return JNI_ENOMEM; 1780 } 1781 1782 // Perform any initialization actions delegated to the policy. 1783 policy()->init(this, &_collection_set); 1784 1785 jint ecode = initialize_concurrent_refinement(); 1786 if (ecode != JNI_OK) { 1787 return ecode; 1788 } 1789 1790 ecode = initialize_young_gen_sampling_thread(); 1791 if (ecode != JNI_OK) { 1792 return ecode; 1793 } 1794 1795 { 1796 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1797 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone()); 1798 dcqs.set_max_cards(concurrent_refine()->red_zone()); 1799 } 1800 1801 // Here we allocate the dummy HeapRegion that is required by the 1802 // G1AllocRegion class. 1803 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1804 1805 // We'll re-use the same region whether the alloc region will 1806 // require BOT updates or not and, if it doesn't, then a non-young 1807 // region will complain that it cannot support allocations without 1808 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1809 dummy_region->set_eden(); 1810 // Make sure it's full. 1811 dummy_region->set_top(dummy_region->end()); 1812 G1AllocRegion::setup(this, dummy_region); 1813 1814 _allocator->init_mutator_alloc_regions(); 1815 1816 // Do create of the monitoring and management support so that 1817 // values in the heap have been properly initialized. 1818 _g1mm = new G1MonitoringSupport(this); 1819 1820 G1StringDedup::initialize(); 1821 1822 _preserved_marks_set.init(ParallelGCThreads); 1823 1824 _collection_set.initialize(max_regions()); 1825 1826 return JNI_OK; 1827 } 1828 1829 void G1CollectedHeap::stop() { 1830 // Stop all concurrent threads. We do this to make sure these threads 1831 // do not continue to execute and access resources (e.g. logging) 1832 // that are destroyed during shutdown. 1833 _cr->stop(); 1834 _young_gen_sampling_thread->stop(); 1835 _cm_thread->stop(); 1836 if (G1StringDedup::is_enabled()) { 1837 G1StringDedup::stop(); 1838 } 1839 } 1840 1841 void G1CollectedHeap::safepoint_synchronize_begin() { 1842 SuspendibleThreadSet::synchronize(); 1843 } 1844 1845 void G1CollectedHeap::safepoint_synchronize_end() { 1846 SuspendibleThreadSet::desynchronize(); 1847 } 1848 1849 void G1CollectedHeap::post_initialize() { 1850 CollectedHeap::post_initialize(); 1851 ref_processing_init(); 1852 } 1853 1854 void G1CollectedHeap::ref_processing_init() { 1855 // Reference processing in G1 currently works as follows: 1856 // 1857 // * There are two reference processor instances. One is 1858 // used to record and process discovered references 1859 // during concurrent marking; the other is used to 1860 // record and process references during STW pauses 1861 // (both full and incremental). 1862 // * Both ref processors need to 'span' the entire heap as 1863 // the regions in the collection set may be dotted around. 1864 // 1865 // * For the concurrent marking ref processor: 1866 // * Reference discovery is enabled at initial marking. 1867 // * Reference discovery is disabled and the discovered 1868 // references processed etc during remarking. 1869 // * Reference discovery is MT (see below). 1870 // * Reference discovery requires a barrier (see below). 1871 // * Reference processing may or may not be MT 1872 // (depending on the value of ParallelRefProcEnabled 1873 // and ParallelGCThreads). 1874 // * A full GC disables reference discovery by the CM 1875 // ref processor and abandons any entries on it's 1876 // discovered lists. 1877 // 1878 // * For the STW processor: 1879 // * Non MT discovery is enabled at the start of a full GC. 1880 // * Processing and enqueueing during a full GC is non-MT. 1881 // * During a full GC, references are processed after marking. 1882 // 1883 // * Discovery (may or may not be MT) is enabled at the start 1884 // of an incremental evacuation pause. 1885 // * References are processed near the end of a STW evacuation pause. 1886 // * For both types of GC: 1887 // * Discovery is atomic - i.e. not concurrent. 1888 // * Reference discovery will not need a barrier. 1889 1890 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1891 1892 // Concurrent Mark ref processor 1893 _ref_processor_cm = 1894 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1895 mt_processing, // mt processing 1896 ParallelGCThreads, // degree of mt processing 1897 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1898 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1899 false, // Reference discovery is not atomic 1900 &_is_alive_closure_cm, // is alive closure 1901 true); // allow changes to number of processing threads 1902 1903 // STW ref processor 1904 _ref_processor_stw = 1905 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1906 mt_processing, // mt processing 1907 ParallelGCThreads, // degree of mt processing 1908 (ParallelGCThreads > 1), // mt discovery 1909 ParallelGCThreads, // degree of mt discovery 1910 true, // Reference discovery is atomic 1911 &_is_alive_closure_stw, // is alive closure 1912 true); // allow changes to number of processing threads 1913 } 1914 1915 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1916 return &_soft_ref_policy; 1917 } 1918 1919 size_t G1CollectedHeap::capacity() const { 1920 return _hrm->length() * HeapRegion::GrainBytes; 1921 } 1922 1923 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1924 return _hrm->total_free_bytes(); 1925 } 1926 1927 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) { 1928 _hot_card_cache->drain(cl, worker_id); 1929 } 1930 1931 // Computes the sum of the storage used by the various regions. 1932 size_t G1CollectedHeap::used() const { 1933 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1934 if (_archive_allocator != NULL) { 1935 result += _archive_allocator->used(); 1936 } 1937 return result; 1938 } 1939 1940 size_t G1CollectedHeap::used_unlocked() const { 1941 return _summary_bytes_used; 1942 } 1943 1944 class SumUsedClosure: public HeapRegionClosure { 1945 size_t _used; 1946 public: 1947 SumUsedClosure() : _used(0) {} 1948 bool do_heap_region(HeapRegion* r) { 1949 _used += r->used(); 1950 return false; 1951 } 1952 size_t result() { return _used; } 1953 }; 1954 1955 size_t G1CollectedHeap::recalculate_used() const { 1956 SumUsedClosure blk; 1957 heap_region_iterate(&blk); 1958 return blk.result(); 1959 } 1960 1961 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1962 switch (cause) { 1963 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1964 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1965 case GCCause::_wb_conc_mark: return true; 1966 default : return false; 1967 } 1968 } 1969 1970 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1971 switch (cause) { 1972 case GCCause::_g1_humongous_allocation: return true; 1973 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 1974 case GCCause::_wb_breakpoint: return true; 1975 default: return is_user_requested_concurrent_full_gc(cause); 1976 } 1977 } 1978 1979 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 1980 if (policy()->force_upgrade_to_full()) { 1981 return true; 1982 } else if (should_do_concurrent_full_gc(_gc_cause)) { 1983 return false; 1984 } else if (has_regions_left_for_allocation()) { 1985 return false; 1986 } else { 1987 return true; 1988 } 1989 } 1990 1991 #ifndef PRODUCT 1992 void G1CollectedHeap::allocate_dummy_regions() { 1993 // Let's fill up most of the region 1994 size_t word_size = HeapRegion::GrainWords - 1024; 1995 // And as a result the region we'll allocate will be humongous. 1996 guarantee(is_humongous(word_size), "sanity"); 1997 1998 // _filler_array_max_size is set to humongous object threshold 1999 // but temporarily change it to use CollectedHeap::fill_with_object(). 2000 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2001 2002 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2003 // Let's use the existing mechanism for the allocation 2004 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2005 if (dummy_obj != NULL) { 2006 MemRegion mr(dummy_obj, word_size); 2007 CollectedHeap::fill_with_object(mr); 2008 } else { 2009 // If we can't allocate once, we probably cannot allocate 2010 // again. Let's get out of the loop. 2011 break; 2012 } 2013 } 2014 } 2015 #endif // !PRODUCT 2016 2017 void G1CollectedHeap::increment_old_marking_cycles_started() { 2018 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2019 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2020 "Wrong marking cycle count (started: %d, completed: %d)", 2021 _old_marking_cycles_started, _old_marking_cycles_completed); 2022 2023 _old_marking_cycles_started++; 2024 } 2025 2026 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2027 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag); 2028 2029 // We assume that if concurrent == true, then the caller is a 2030 // concurrent thread that was joined the Suspendible Thread 2031 // Set. If there's ever a cheap way to check this, we should add an 2032 // assert here. 2033 2034 // Given that this method is called at the end of a Full GC or of a 2035 // concurrent cycle, and those can be nested (i.e., a Full GC can 2036 // interrupt a concurrent cycle), the number of full collections 2037 // completed should be either one (in the case where there was no 2038 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2039 // behind the number of full collections started. 2040 2041 // This is the case for the inner caller, i.e. a Full GC. 2042 assert(concurrent || 2043 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2044 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2045 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2046 "is inconsistent with _old_marking_cycles_completed = %u", 2047 _old_marking_cycles_started, _old_marking_cycles_completed); 2048 2049 // This is the case for the outer caller, i.e. the concurrent cycle. 2050 assert(!concurrent || 2051 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2052 "for outer caller (concurrent cycle): " 2053 "_old_marking_cycles_started = %u " 2054 "is inconsistent with _old_marking_cycles_completed = %u", 2055 _old_marking_cycles_started, _old_marking_cycles_completed); 2056 2057 _old_marking_cycles_completed += 1; 2058 2059 // We need to clear the "in_progress" flag in the CM thread before 2060 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2061 // is set) so that if a waiter requests another System.gc() it doesn't 2062 // incorrectly see that a marking cycle is still in progress. 2063 if (concurrent) { 2064 _cm_thread->set_idle(); 2065 } 2066 2067 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent) 2068 // for a full GC to finish that their wait is over. 2069 ml.notify_all(); 2070 } 2071 2072 void G1CollectedHeap::collect(GCCause::Cause cause) { 2073 try_collect(cause); 2074 } 2075 2076 // Return true if (x < y) with allowance for wraparound. 2077 static bool gc_counter_less_than(uint x, uint y) { 2078 return (x - y) > (UINT_MAX/2); 2079 } 2080 2081 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...) 2082 // Macro so msg printing is format-checked. 2083 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \ 2084 do { \ 2085 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \ 2086 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \ 2087 ResourceMark rm; /* For thread name. */ \ 2088 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \ 2089 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \ 2090 Thread::current()->name(), \ 2091 GCCause::to_string(cause)); \ 2092 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \ 2093 } \ 2094 } while (0) 2095 2096 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \ 2097 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result)) 2098 2099 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause, 2100 uint gc_counter, 2101 uint old_marking_started_before) { 2102 assert_heap_not_locked(); 2103 assert(should_do_concurrent_full_gc(cause), 2104 "Non-concurrent cause %s", GCCause::to_string(cause)); 2105 2106 for (uint i = 1; true; ++i) { 2107 // Try to schedule an initial-mark evacuation pause that will 2108 // start a concurrent cycle. 2109 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i); 2110 VM_G1TryInitiateConcMark op(gc_counter, 2111 cause, 2112 policy()->max_pause_time_ms()); 2113 VMThread::execute(&op); 2114 2115 // Request is trivially finished. 2116 if (cause == GCCause::_g1_periodic_collection) { 2117 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded()); 2118 return op.gc_succeeded(); 2119 } 2120 2121 // If VMOp skipped initiating concurrent marking cycle because 2122 // we're terminating, then we're done. 2123 if (op.terminating()) { 2124 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating"); 2125 return false; 2126 } 2127 2128 // Lock to get consistent set of values. 2129 uint old_marking_started_after; 2130 uint old_marking_completed_after; 2131 { 2132 MutexLocker ml(Heap_lock); 2133 // Update gc_counter for retrying VMOp if needed. Captured here to be 2134 // consistent with the values we use below for termination tests. If 2135 // a retry is needed after a possible wait, and another collection 2136 // occurs in the meantime, it will cause our retry to be skipped and 2137 // we'll recheck for termination with updated conditions from that 2138 // more recent collection. That's what we want, rather than having 2139 // our retry possibly perform an unnecessary collection. 2140 gc_counter = total_collections(); 2141 old_marking_started_after = _old_marking_cycles_started; 2142 old_marking_completed_after = _old_marking_cycles_completed; 2143 } 2144 2145 if (cause == GCCause::_wb_breakpoint) { 2146 if (op.gc_succeeded()) { 2147 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2148 return true; 2149 } 2150 // When _wb_breakpoint there can't be another cycle or deferred. 2151 assert(!op.cycle_already_in_progress(), "invariant"); 2152 assert(!op.whitebox_attached(), "invariant"); 2153 // Concurrent cycle attempt might have been cancelled by some other 2154 // collection, so retry. Unlike other cases below, we want to retry 2155 // even if cancelled by a STW full collection, because we really want 2156 // to start a concurrent cycle. 2157 if (old_marking_started_before != old_marking_started_after) { 2158 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC"); 2159 old_marking_started_before = old_marking_started_after; 2160 } 2161 } else if (!GCCause::is_user_requested_gc(cause)) { 2162 // For an "automatic" (not user-requested) collection, we just need to 2163 // ensure that progress is made. 2164 // 2165 // Request is finished if any of 2166 // (1) the VMOp successfully performed a GC, 2167 // (2) a concurrent cycle was already in progress, 2168 // (3) whitebox is controlling concurrent cycles, 2169 // (4) a new cycle was started (by this thread or some other), or 2170 // (5) a Full GC was performed. 2171 // Cases (4) and (5) are detected together by a change to 2172 // _old_marking_cycles_started. 2173 // 2174 // Note that (1) does not imply (4). If we're still in the mixed 2175 // phase of an earlier concurrent collection, the request to make the 2176 // collection an initial-mark won't be honored. If we don't check for 2177 // both conditions we'll spin doing back-to-back collections. 2178 if (op.gc_succeeded() || 2179 op.cycle_already_in_progress() || 2180 op.whitebox_attached() || 2181 (old_marking_started_before != old_marking_started_after)) { 2182 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2183 return true; 2184 } 2185 } else { // User-requested GC. 2186 // For a user-requested collection, we want to ensure that a complete 2187 // full collection has been performed before returning, but without 2188 // waiting for more than needed. 2189 2190 // For user-requested GCs (unlike non-UR), a successful VMOp implies a 2191 // new cycle was started. That's good, because it's not clear what we 2192 // should do otherwise. Trying again just does back to back GCs. 2193 // Can't wait for someone else to start a cycle. And returning fails 2194 // to meet the goal of ensuring a full collection was performed. 2195 assert(!op.gc_succeeded() || 2196 (old_marking_started_before != old_marking_started_after), 2197 "invariant: succeeded %s, started before %u, started after %u", 2198 BOOL_TO_STR(op.gc_succeeded()), 2199 old_marking_started_before, old_marking_started_after); 2200 2201 // Request is finished if a full collection (concurrent or stw) 2202 // was started after this request and has completed, e.g. 2203 // started_before < completed_after. 2204 if (gc_counter_less_than(old_marking_started_before, 2205 old_marking_completed_after)) { 2206 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true); 2207 return true; 2208 } 2209 2210 if (old_marking_started_after != old_marking_completed_after) { 2211 // If there is an in-progress cycle (possibly started by us), then 2212 // wait for that cycle to complete, e.g. 2213 // while completed_now < started_after. 2214 LOG_COLLECT_CONCURRENTLY(cause, "wait"); 2215 MonitorLocker ml(G1OldGCCount_lock); 2216 while (gc_counter_less_than(_old_marking_cycles_completed, 2217 old_marking_started_after)) { 2218 ml.wait(); 2219 } 2220 // Request is finished if the collection we just waited for was 2221 // started after this request. 2222 if (old_marking_started_before != old_marking_started_after) { 2223 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait"); 2224 return true; 2225 } 2226 } 2227 2228 // If VMOp was successful then it started a new cycle that the above 2229 // wait &etc should have recognized as finishing this request. This 2230 // differs from a non-user-request, where gc_succeeded does not imply 2231 // a new cycle was started. 2232 assert(!op.gc_succeeded(), "invariant"); 2233 2234 if (op.cycle_already_in_progress()) { 2235 // If VMOp failed because a cycle was already in progress, it 2236 // is now complete. But it didn't finish this user-requested 2237 // GC, so try again. 2238 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress"); 2239 continue; 2240 } else if (op.whitebox_attached()) { 2241 // If WhiteBox wants control, wait for notification of a state 2242 // change in the controller, then try again. Don't wait for 2243 // release of control, since collections may complete while in 2244 // control. Note: This won't recognize a STW full collection 2245 // while waiting; we can't wait on multiple monitors. 2246 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall"); 2247 MonitorLocker ml(ConcurrentGCBreakpoints::monitor()); 2248 if (ConcurrentGCBreakpoints::is_controlled()) { 2249 ml.wait(); 2250 } 2251 continue; 2252 } 2253 } 2254 2255 // Collection failed and should be retried. 2256 assert(op.transient_failure(), "invariant"); 2257 2258 if (GCLocker::is_active_and_needs_gc()) { 2259 // If GCLocker is active, wait until clear before retrying. 2260 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall"); 2261 GCLocker::stall_until_clear(); 2262 } 2263 2264 LOG_COLLECT_CONCURRENTLY(cause, "retry"); 2265 } 2266 } 2267 2268 bool G1CollectedHeap::try_collect(GCCause::Cause cause) { 2269 assert_heap_not_locked(); 2270 2271 // Lock to get consistent set of values. 2272 uint gc_count_before; 2273 uint full_gc_count_before; 2274 uint old_marking_started_before; 2275 { 2276 MutexLocker ml(Heap_lock); 2277 gc_count_before = total_collections(); 2278 full_gc_count_before = total_full_collections(); 2279 old_marking_started_before = _old_marking_cycles_started; 2280 } 2281 2282 if (should_do_concurrent_full_gc(cause)) { 2283 return try_collect_concurrently(cause, 2284 gc_count_before, 2285 old_marking_started_before); 2286 } else if (GCLocker::should_discard(cause, gc_count_before)) { 2287 // Indicate failure to be consistent with VMOp failure due to 2288 // another collection slipping in after our gc_count but before 2289 // our request is processed. 2290 return false; 2291 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2292 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2293 2294 // Schedule a standard evacuation pause. We're setting word_size 2295 // to 0 which means that we are not requesting a post-GC allocation. 2296 VM_G1CollectForAllocation op(0, /* word_size */ 2297 gc_count_before, 2298 cause, 2299 policy()->max_pause_time_ms()); 2300 VMThread::execute(&op); 2301 return op.gc_succeeded(); 2302 } else { 2303 // Schedule a Full GC. 2304 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2305 VMThread::execute(&op); 2306 return op.gc_succeeded(); 2307 } 2308 } 2309 2310 bool G1CollectedHeap::is_in(const void* p) const { 2311 if (_hrm->reserved().contains(p)) { 2312 // Given that we know that p is in the reserved space, 2313 // heap_region_containing() should successfully 2314 // return the containing region. 2315 HeapRegion* hr = heap_region_containing(p); 2316 return hr->is_in(p); 2317 } else { 2318 return false; 2319 } 2320 } 2321 2322 #ifdef ASSERT 2323 bool G1CollectedHeap::is_in_exact(const void* p) const { 2324 bool contains = reserved_region().contains(p); 2325 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2326 if (contains && available) { 2327 return true; 2328 } else { 2329 return false; 2330 } 2331 } 2332 #endif 2333 2334 // Iteration functions. 2335 2336 // Iterates an ObjectClosure over all objects within a HeapRegion. 2337 2338 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2339 ObjectClosure* _cl; 2340 public: 2341 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2342 bool do_heap_region(HeapRegion* r) { 2343 if (!r->is_continues_humongous()) { 2344 r->object_iterate(_cl); 2345 } 2346 return false; 2347 } 2348 }; 2349 2350 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2351 IterateObjectClosureRegionClosure blk(cl); 2352 heap_region_iterate(&blk); 2353 } 2354 2355 void G1CollectedHeap::keep_alive(oop obj) { 2356 G1BarrierSet::enqueue(obj); 2357 } 2358 2359 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2360 _hrm->iterate(cl); 2361 } 2362 2363 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2364 HeapRegionClaimer *hrclaimer, 2365 uint worker_id) const { 2366 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2367 } 2368 2369 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2370 HeapRegionClaimer *hrclaimer) const { 2371 _hrm->par_iterate(cl, hrclaimer, 0); 2372 } 2373 2374 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) { 2375 _collection_set.iterate(cl); 2376 } 2377 2378 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2379 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers()); 2380 } 2381 2382 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) { 2383 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers()); 2384 } 2385 2386 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2387 HeapRegion* hr = heap_region_containing(addr); 2388 return hr->block_start(addr); 2389 } 2390 2391 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2392 HeapRegion* hr = heap_region_containing(addr); 2393 return hr->block_is_obj(addr); 2394 } 2395 2396 bool G1CollectedHeap::supports_tlab_allocation() const { 2397 return true; 2398 } 2399 2400 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2401 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2402 } 2403 2404 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2405 return _eden.length() * HeapRegion::GrainBytes; 2406 } 2407 2408 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2409 // must be equal to the humongous object limit. 2410 size_t G1CollectedHeap::max_tlab_size() const { 2411 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2412 } 2413 2414 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2415 return _allocator->unsafe_max_tlab_alloc(); 2416 } 2417 2418 size_t G1CollectedHeap::max_capacity() const { 2419 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2420 } 2421 2422 size_t G1CollectedHeap::max_reserved_capacity() const { 2423 return _hrm->max_length() * HeapRegion::GrainBytes; 2424 } 2425 2426 jlong G1CollectedHeap::millis_since_last_gc() { 2427 // See the notes in GenCollectedHeap::millis_since_last_gc() 2428 // for more information about the implementation. 2429 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2430 _policy->collection_pause_end_millis(); 2431 if (ret_val < 0) { 2432 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2433 ". returning zero instead.", ret_val); 2434 return 0; 2435 } 2436 return ret_val; 2437 } 2438 2439 void G1CollectedHeap::deduplicate_string(oop str) { 2440 assert(java_lang_String::is_instance(str), "invariant"); 2441 2442 if (G1StringDedup::is_enabled()) { 2443 G1StringDedup::deduplicate(str); 2444 } 2445 } 2446 2447 void G1CollectedHeap::prepare_for_verify() { 2448 _verifier->prepare_for_verify(); 2449 } 2450 2451 void G1CollectedHeap::verify(VerifyOption vo) { 2452 _verifier->verify(vo); 2453 } 2454 2455 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const { 2456 return true; 2457 } 2458 2459 bool G1CollectedHeap::is_heterogeneous_heap() const { 2460 return G1Arguments::is_heterogeneous_heap(); 2461 } 2462 2463 class PrintRegionClosure: public HeapRegionClosure { 2464 outputStream* _st; 2465 public: 2466 PrintRegionClosure(outputStream* st) : _st(st) {} 2467 bool do_heap_region(HeapRegion* r) { 2468 r->print_on(_st); 2469 return false; 2470 } 2471 }; 2472 2473 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2474 const HeapRegion* hr, 2475 const VerifyOption vo) const { 2476 switch (vo) { 2477 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2478 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2479 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2480 default: ShouldNotReachHere(); 2481 } 2482 return false; // keep some compilers happy 2483 } 2484 2485 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2486 const VerifyOption vo) const { 2487 switch (vo) { 2488 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2489 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2490 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2491 default: ShouldNotReachHere(); 2492 } 2493 return false; // keep some compilers happy 2494 } 2495 2496 void G1CollectedHeap::print_heap_regions() const { 2497 LogTarget(Trace, gc, heap, region) lt; 2498 if (lt.is_enabled()) { 2499 LogStream ls(lt); 2500 print_regions_on(&ls); 2501 } 2502 } 2503 2504 void G1CollectedHeap::print_on(outputStream* st) const { 2505 st->print(" %-20s", "garbage-first heap"); 2506 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2507 capacity()/K, used_unlocked()/K); 2508 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2509 p2i(_hrm->reserved().start()), 2510 p2i(_hrm->reserved().end())); 2511 st->cr(); 2512 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2513 uint young_regions = young_regions_count(); 2514 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2515 (size_t) young_regions * HeapRegion::GrainBytes / K); 2516 uint survivor_regions = survivor_regions_count(); 2517 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2518 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2519 st->cr(); 2520 if (_numa->is_enabled()) { 2521 uint num_nodes = _numa->num_active_nodes(); 2522 st->print(" remaining free region(s) on each NUMA node: "); 2523 const int* node_ids = _numa->node_ids(); 2524 for (uint node_index = 0; node_index < num_nodes; node_index++) { 2525 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index)); 2526 } 2527 st->cr(); 2528 } 2529 MetaspaceUtils::print_on(st); 2530 } 2531 2532 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2533 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2534 "HS=humongous(starts), HC=humongous(continues), " 2535 "CS=collection set, F=free, " 2536 "OA=open archive, CA=closed archive, " 2537 "TAMS=top-at-mark-start (previous, next)"); 2538 PrintRegionClosure blk(st); 2539 heap_region_iterate(&blk); 2540 } 2541 2542 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2543 print_on(st); 2544 2545 // Print the per-region information. 2546 print_regions_on(st); 2547 } 2548 2549 void G1CollectedHeap::print_on_error(outputStream* st) const { 2550 this->CollectedHeap::print_on_error(st); 2551 2552 if (_cm != NULL) { 2553 st->cr(); 2554 _cm->print_on_error(st); 2555 } 2556 } 2557 2558 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2559 workers()->print_worker_threads_on(st); 2560 _cm_thread->print_on(st); 2561 st->cr(); 2562 _cm->print_worker_threads_on(st); 2563 _cr->print_threads_on(st); 2564 _young_gen_sampling_thread->print_on(st); 2565 if (G1StringDedup::is_enabled()) { 2566 G1StringDedup::print_worker_threads_on(st); 2567 } 2568 } 2569 2570 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2571 workers()->threads_do(tc); 2572 tc->do_thread(_cm_thread); 2573 _cm->threads_do(tc); 2574 _cr->threads_do(tc); 2575 tc->do_thread(_young_gen_sampling_thread); 2576 if (G1StringDedup::is_enabled()) { 2577 G1StringDedup::threads_do(tc); 2578 } 2579 } 2580 2581 void G1CollectedHeap::print_tracing_info() const { 2582 rem_set()->print_summary_info(); 2583 concurrent_mark()->print_summary_info(); 2584 } 2585 2586 #ifndef PRODUCT 2587 // Helpful for debugging RSet issues. 2588 2589 class PrintRSetsClosure : public HeapRegionClosure { 2590 private: 2591 const char* _msg; 2592 size_t _occupied_sum; 2593 2594 public: 2595 bool do_heap_region(HeapRegion* r) { 2596 HeapRegionRemSet* hrrs = r->rem_set(); 2597 size_t occupied = hrrs->occupied(); 2598 _occupied_sum += occupied; 2599 2600 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2601 if (occupied == 0) { 2602 tty->print_cr(" RSet is empty"); 2603 } else { 2604 hrrs->print(); 2605 } 2606 tty->print_cr("----------"); 2607 return false; 2608 } 2609 2610 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2611 tty->cr(); 2612 tty->print_cr("========================================"); 2613 tty->print_cr("%s", msg); 2614 tty->cr(); 2615 } 2616 2617 ~PrintRSetsClosure() { 2618 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2619 tty->print_cr("========================================"); 2620 tty->cr(); 2621 } 2622 }; 2623 2624 void G1CollectedHeap::print_cset_rsets() { 2625 PrintRSetsClosure cl("Printing CSet RSets"); 2626 collection_set_iterate_all(&cl); 2627 } 2628 2629 void G1CollectedHeap::print_all_rsets() { 2630 PrintRSetsClosure cl("Printing All RSets");; 2631 heap_region_iterate(&cl); 2632 } 2633 #endif // PRODUCT 2634 2635 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const { 2636 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr); 2637 } 2638 2639 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2640 2641 size_t eden_used_bytes = _eden.used_bytes(); 2642 size_t survivor_used_bytes = _survivor.used_bytes(); 2643 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2644 2645 size_t eden_capacity_bytes = 2646 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2647 2648 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2649 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2650 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2651 } 2652 2653 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2654 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2655 stats->unused(), stats->used(), stats->region_end_waste(), 2656 stats->regions_filled(), stats->direct_allocated(), 2657 stats->failure_used(), stats->failure_waste()); 2658 } 2659 2660 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2661 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2662 gc_tracer->report_gc_heap_summary(when, heap_summary); 2663 2664 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2665 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2666 } 2667 2668 G1CollectedHeap* G1CollectedHeap::heap() { 2669 CollectedHeap* heap = Universe::heap(); 2670 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2671 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2672 return (G1CollectedHeap*)heap; 2673 } 2674 2675 void G1CollectedHeap::gc_prologue(bool full) { 2676 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2677 2678 // This summary needs to be printed before incrementing total collections. 2679 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2680 2681 // Update common counters. 2682 increment_total_collections(full /* full gc */); 2683 if (full || collector_state()->in_initial_mark_gc()) { 2684 increment_old_marking_cycles_started(); 2685 } 2686 2687 // Fill TLAB's and such 2688 { 2689 Ticks start = Ticks::now(); 2690 ensure_parsability(true); 2691 Tickspan dt = Ticks::now() - start; 2692 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS); 2693 } 2694 2695 if (!full) { 2696 // Flush dirty card queues to qset, so later phases don't need to account 2697 // for partially filled per-thread queues and such. Not needed for full 2698 // collections, which ignore those logs. 2699 Ticks start = Ticks::now(); 2700 G1BarrierSet::dirty_card_queue_set().concatenate_logs(); 2701 Tickspan dt = Ticks::now() - start; 2702 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS); 2703 } 2704 } 2705 2706 void G1CollectedHeap::gc_epilogue(bool full) { 2707 // Update common counters. 2708 if (full) { 2709 // Update the number of full collections that have been completed. 2710 increment_old_marking_cycles_completed(false /* concurrent */); 2711 } 2712 2713 // We are at the end of the GC. Total collections has already been increased. 2714 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2715 2716 // FIXME: what is this about? 2717 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2718 // is set. 2719 #if COMPILER2_OR_JVMCI 2720 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2721 #endif 2722 2723 double start = os::elapsedTime(); 2724 resize_all_tlabs(); 2725 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2726 2727 MemoryService::track_memory_usage(); 2728 // We have just completed a GC. Update the soft reference 2729 // policy with the new heap occupancy 2730 Universe::update_heap_info_at_gc(); 2731 2732 // Print NUMA statistics. 2733 _numa->print_statistics(); 2734 } 2735 2736 void G1CollectedHeap::verify_numa_regions(const char* desc) { 2737 LogTarget(Trace, gc, heap, verify) lt; 2738 2739 if (lt.is_enabled()) { 2740 LogStream ls(lt); 2741 // Iterate all heap regions to print matching between preferred numa id and actual numa id. 2742 G1NodeIndexCheckClosure cl(desc, _numa, &ls); 2743 heap_region_iterate(&cl); 2744 } 2745 } 2746 2747 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2748 uint gc_count_before, 2749 bool* succeeded, 2750 GCCause::Cause gc_cause) { 2751 assert_heap_not_locked_and_not_at_safepoint(); 2752 VM_G1CollectForAllocation op(word_size, 2753 gc_count_before, 2754 gc_cause, 2755 policy()->max_pause_time_ms()); 2756 VMThread::execute(&op); 2757 2758 HeapWord* result = op.result(); 2759 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2760 assert(result == NULL || ret_succeeded, 2761 "the result should be NULL if the VM did not succeed"); 2762 *succeeded = ret_succeeded; 2763 2764 assert_heap_not_locked(); 2765 return result; 2766 } 2767 2768 void G1CollectedHeap::do_concurrent_mark() { 2769 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag); 2770 if (!_cm_thread->in_progress()) { 2771 _cm_thread->set_started(); 2772 CGC_lock->notify(); 2773 } 2774 } 2775 2776 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2777 // We don't nominate objects with many remembered set entries, on 2778 // the assumption that such objects are likely still live. 2779 HeapRegionRemSet* rem_set = r->rem_set(); 2780 2781 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2782 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2783 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2784 } 2785 2786 #ifndef PRODUCT 2787 void G1CollectedHeap::verify_region_attr_remset_update() { 2788 class VerifyRegionAttrRemSet : public HeapRegionClosure { 2789 public: 2790 virtual bool do_heap_region(HeapRegion* r) { 2791 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2792 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update(); 2793 assert(r->rem_set()->is_tracked() == needs_remset_update, 2794 "Region %u remset tracking status (%s) different to region attribute (%s)", 2795 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update)); 2796 return false; 2797 } 2798 } cl; 2799 heap_region_iterate(&cl); 2800 } 2801 #endif 2802 2803 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2804 public: 2805 bool do_heap_region(HeapRegion* hr) { 2806 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2807 hr->verify_rem_set(); 2808 } 2809 return false; 2810 } 2811 }; 2812 2813 uint G1CollectedHeap::num_task_queues() const { 2814 return _task_queues->size(); 2815 } 2816 2817 #if TASKQUEUE_STATS 2818 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2819 st->print_raw_cr("GC Task Stats"); 2820 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2821 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2822 } 2823 2824 void G1CollectedHeap::print_taskqueue_stats() const { 2825 if (!log_is_enabled(Trace, gc, task, stats)) { 2826 return; 2827 } 2828 Log(gc, task, stats) log; 2829 ResourceMark rm; 2830 LogStream ls(log.trace()); 2831 outputStream* st = &ls; 2832 2833 print_taskqueue_stats_hdr(st); 2834 2835 TaskQueueStats totals; 2836 const uint n = num_task_queues(); 2837 for (uint i = 0; i < n; ++i) { 2838 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2839 totals += task_queue(i)->stats; 2840 } 2841 st->print_raw("tot "); totals.print(st); st->cr(); 2842 2843 DEBUG_ONLY(totals.verify()); 2844 } 2845 2846 void G1CollectedHeap::reset_taskqueue_stats() { 2847 const uint n = num_task_queues(); 2848 for (uint i = 0; i < n; ++i) { 2849 task_queue(i)->stats.reset(); 2850 } 2851 } 2852 #endif // TASKQUEUE_STATS 2853 2854 void G1CollectedHeap::wait_for_root_region_scanning() { 2855 double scan_wait_start = os::elapsedTime(); 2856 // We have to wait until the CM threads finish scanning the 2857 // root regions as it's the only way to ensure that all the 2858 // objects on them have been correctly scanned before we start 2859 // moving them during the GC. 2860 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2861 double wait_time_ms = 0.0; 2862 if (waited) { 2863 double scan_wait_end = os::elapsedTime(); 2864 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2865 } 2866 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2867 } 2868 2869 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2870 private: 2871 G1HRPrinter* _hr_printer; 2872 public: 2873 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2874 2875 virtual bool do_heap_region(HeapRegion* r) { 2876 _hr_printer->cset(r); 2877 return false; 2878 } 2879 }; 2880 2881 void G1CollectedHeap::start_new_collection_set() { 2882 double start = os::elapsedTime(); 2883 2884 collection_set()->start_incremental_building(); 2885 2886 clear_region_attr(); 2887 2888 guarantee(_eden.length() == 0, "eden should have been cleared"); 2889 policy()->transfer_survivors_to_cset(survivor()); 2890 2891 // We redo the verification but now wrt to the new CSet which 2892 // has just got initialized after the previous CSet was freed. 2893 _cm->verify_no_collection_set_oops(); 2894 2895 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2896 } 2897 2898 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) { 2899 2900 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor); 2901 evacuation_info.set_collectionset_regions(collection_set()->region_length() + 2902 collection_set()->optional_region_length()); 2903 2904 _cm->verify_no_collection_set_oops(); 2905 2906 if (_hr_printer.is_active()) { 2907 G1PrintCollectionSetClosure cl(&_hr_printer); 2908 _collection_set.iterate(&cl); 2909 _collection_set.iterate_optional(&cl); 2910 } 2911 } 2912 2913 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2914 if (collector_state()->in_initial_mark_gc()) { 2915 return G1HeapVerifier::G1VerifyConcurrentStart; 2916 } else if (collector_state()->in_young_only_phase()) { 2917 return G1HeapVerifier::G1VerifyYoungNormal; 2918 } else { 2919 return G1HeapVerifier::G1VerifyMixed; 2920 } 2921 } 2922 2923 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2924 if (VerifyRememberedSets) { 2925 log_info(gc, verify)("[Verifying RemSets before GC]"); 2926 VerifyRegionRemSetClosure v_cl; 2927 heap_region_iterate(&v_cl); 2928 } 2929 _verifier->verify_before_gc(type); 2930 _verifier->check_bitmaps("GC Start"); 2931 verify_numa_regions("GC Start"); 2932 } 2933 2934 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2935 if (VerifyRememberedSets) { 2936 log_info(gc, verify)("[Verifying RemSets after GC]"); 2937 VerifyRegionRemSetClosure v_cl; 2938 heap_region_iterate(&v_cl); 2939 } 2940 _verifier->verify_after_gc(type); 2941 _verifier->check_bitmaps("GC End"); 2942 verify_numa_regions("GC End"); 2943 } 2944 2945 void G1CollectedHeap::expand_heap_after_young_collection(){ 2946 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2947 if (expand_bytes > 0) { 2948 // No need for an ergo logging here, 2949 // expansion_amount() does this when it returns a value > 0. 2950 double expand_ms; 2951 if (!expand(expand_bytes, _workers, &expand_ms)) { 2952 // We failed to expand the heap. Cannot do anything about it. 2953 } 2954 phase_times()->record_expand_heap_time(expand_ms); 2955 } 2956 } 2957 2958 const char* G1CollectedHeap::young_gc_name() const { 2959 if (collector_state()->in_initial_mark_gc()) { 2960 return "Pause Young (Concurrent Start)"; 2961 } else if (collector_state()->in_young_only_phase()) { 2962 if (collector_state()->in_young_gc_before_mixed()) { 2963 return "Pause Young (Prepare Mixed)"; 2964 } else { 2965 return "Pause Young (Normal)"; 2966 } 2967 } else { 2968 return "Pause Young (Mixed)"; 2969 } 2970 } 2971 2972 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2973 assert_at_safepoint_on_vm_thread(); 2974 guarantee(!is_gc_active(), "collection is not reentrant"); 2975 2976 if (GCLocker::check_active_before_gc()) { 2977 return false; 2978 } 2979 2980 do_collection_pause_at_safepoint_helper(target_pause_time_ms); 2981 if (should_upgrade_to_full_gc(gc_cause())) { 2982 log_info(gc, ergo)("Attempting maximally compacting collection"); 2983 bool result = do_full_collection(false /* explicit gc */, 2984 true /* clear_all_soft_refs */); 2985 // do_full_collection only fails if blocked by GC locker, but 2986 // we've already checked for that above. 2987 assert(result, "invariant"); 2988 } 2989 return true; 2990 } 2991 2992 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) { 2993 GCIdMark gc_id_mark; 2994 2995 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2996 ResourceMark rm; 2997 2998 policy()->note_gc_start(); 2999 3000 _gc_timer_stw->register_gc_start(); 3001 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 3002 3003 wait_for_root_region_scanning(); 3004 3005 print_heap_before_gc(); 3006 print_heap_regions(); 3007 trace_heap_before_gc(_gc_tracer_stw); 3008 3009 _verifier->verify_region_sets_optional(); 3010 _verifier->verify_dirty_young_regions(); 3011 3012 // We should not be doing initial mark unless the conc mark thread is running 3013 if (!_cm_thread->should_terminate()) { 3014 // This call will decide whether this pause is an initial-mark 3015 // pause. If it is, in_initial_mark_gc() will return true 3016 // for the duration of this pause. 3017 policy()->decide_on_conc_mark_initiation(); 3018 } 3019 3020 // We do not allow initial-mark to be piggy-backed on a mixed GC. 3021 assert(!collector_state()->in_initial_mark_gc() || 3022 collector_state()->in_young_only_phase(), "sanity"); 3023 // We also do not allow mixed GCs during marking. 3024 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 3025 3026 // Record whether this pause is an initial mark. When the current 3027 // thread has completed its logging output and it's safe to signal 3028 // the CM thread, the flag's value in the policy has been reset. 3029 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 3030 if (should_start_conc_mark) { 3031 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 3032 } 3033 3034 // Inner scope for scope based logging, timers, and stats collection 3035 { 3036 G1EvacuationInfo evacuation_info; 3037 3038 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3039 3040 GCTraceCPUTime tcpu; 3041 3042 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3043 3044 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3045 workers()->active_workers(), 3046 Threads::number_of_non_daemon_threads()); 3047 active_workers = workers()->update_active_workers(active_workers); 3048 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3049 3050 G1MonitoringScope ms(g1mm(), 3051 false /* full_gc */, 3052 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3053 3054 G1HeapTransition heap_transition(this); 3055 3056 { 3057 IsGCActiveMark x; 3058 3059 gc_prologue(false); 3060 3061 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3062 verify_before_young_collection(verify_type); 3063 3064 { 3065 // The elapsed time induced by the start time below deliberately elides 3066 // the possible verification above. 3067 double sample_start_time_sec = os::elapsedTime(); 3068 3069 // Please see comment in g1CollectedHeap.hpp and 3070 // G1CollectedHeap::ref_processing_init() to see how 3071 // reference processing currently works in G1. 3072 _ref_processor_stw->enable_discovery(); 3073 3074 // We want to temporarily turn off discovery by the 3075 // CM ref processor, if necessary, and turn it back on 3076 // on again later if we do. Using a scoped 3077 // NoRefDiscovery object will do this. 3078 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3079 3080 policy()->record_collection_pause_start(sample_start_time_sec); 3081 3082 // Forget the current allocation region (we might even choose it to be part 3083 // of the collection set!). 3084 _allocator->release_mutator_alloc_regions(); 3085 3086 calculate_collection_set(evacuation_info, target_pause_time_ms); 3087 3088 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator()); 3089 G1ParScanThreadStateSet per_thread_states(this, 3090 &rdcqs, 3091 workers()->active_workers(), 3092 collection_set()->young_region_length(), 3093 collection_set()->optional_region_length()); 3094 pre_evacuate_collection_set(evacuation_info, &per_thread_states); 3095 3096 // Actually do the work... 3097 evacuate_initial_collection_set(&per_thread_states); 3098 3099 if (_collection_set.optional_region_length() != 0) { 3100 evacuate_optional_collection_set(&per_thread_states); 3101 } 3102 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states); 3103 3104 start_new_collection_set(); 3105 3106 _survivor_evac_stats.adjust_desired_plab_sz(); 3107 _old_evac_stats.adjust_desired_plab_sz(); 3108 3109 if (should_start_conc_mark) { 3110 // We have to do this before we notify the CM threads that 3111 // they can start working to make sure that all the 3112 // appropriate initialization is done on the CM object. 3113 concurrent_mark()->post_initial_mark(); 3114 // Note that we don't actually trigger the CM thread at 3115 // this point. We do that later when we're sure that 3116 // the current thread has completed its logging output. 3117 } 3118 3119 allocate_dummy_regions(); 3120 3121 _allocator->init_mutator_alloc_regions(); 3122 3123 expand_heap_after_young_collection(); 3124 3125 double sample_end_time_sec = os::elapsedTime(); 3126 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3127 policy()->record_collection_pause_end(pause_time_ms); 3128 } 3129 3130 verify_after_young_collection(verify_type); 3131 3132 gc_epilogue(false); 3133 } 3134 3135 // Print the remainder of the GC log output. 3136 if (evacuation_failed()) { 3137 log_info(gc)("To-space exhausted"); 3138 } 3139 3140 policy()->print_phases(); 3141 heap_transition.print(); 3142 3143 _hrm->verify_optional(); 3144 _verifier->verify_region_sets_optional(); 3145 3146 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3147 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3148 3149 print_heap_after_gc(); 3150 print_heap_regions(); 3151 trace_heap_after_gc(_gc_tracer_stw); 3152 3153 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3154 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3155 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3156 // before any GC notifications are raised. 3157 g1mm()->update_sizes(); 3158 3159 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3160 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3161 _gc_timer_stw->register_gc_end(); 3162 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3163 } 3164 // It should now be safe to tell the concurrent mark thread to start 3165 // without its logging output interfering with the logging output 3166 // that came from the pause. 3167 3168 if (should_start_conc_mark) { 3169 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3170 // thread(s) could be running concurrently with us. Make sure that anything 3171 // after this point does not assume that we are the only GC thread running. 3172 // Note: of course, the actual marking work will not start until the safepoint 3173 // itself is released in SuspendibleThreadSet::desynchronize(). 3174 do_concurrent_mark(); 3175 ConcurrentGCBreakpoints::notify_idle_to_active(); 3176 } 3177 } 3178 3179 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) { 3180 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs); 3181 workers()->run_task(&rsfp_task); 3182 } 3183 3184 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) { 3185 double remove_self_forwards_start = os::elapsedTime(); 3186 3187 remove_self_forwarding_pointers(rdcqs); 3188 _preserved_marks_set.restore(workers()); 3189 3190 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3191 } 3192 3193 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) { 3194 if (!_evacuation_failed) { 3195 _evacuation_failed = true; 3196 } 3197 3198 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3199 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3200 } 3201 3202 bool G1ParEvacuateFollowersClosure::offer_termination() { 3203 EventGCPhaseParallel event; 3204 G1ParScanThreadState* const pss = par_scan_state(); 3205 start_term_time(); 3206 const bool res = terminator()->offer_termination(); 3207 end_term_time(); 3208 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3209 return res; 3210 } 3211 3212 void G1ParEvacuateFollowersClosure::do_void() { 3213 EventGCPhaseParallel event; 3214 G1ParScanThreadState* const pss = par_scan_state(); 3215 pss->trim_queue(); 3216 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3217 do { 3218 EventGCPhaseParallel event; 3219 pss->steal_and_trim_queue(queues()); 3220 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3221 } while (!offer_termination()); 3222 } 3223 3224 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3225 bool class_unloading_occurred) { 3226 uint num_workers = workers()->active_workers(); 3227 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3228 workers()->run_task(&unlink_task); 3229 } 3230 3231 // Clean string dedup data structures. 3232 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3233 // record the durations of the phases. Hence the almost-copy. 3234 class G1StringDedupCleaningTask : public AbstractGangTask { 3235 BoolObjectClosure* _is_alive; 3236 OopClosure* _keep_alive; 3237 G1GCPhaseTimes* _phase_times; 3238 3239 public: 3240 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3241 OopClosure* keep_alive, 3242 G1GCPhaseTimes* phase_times) : 3243 AbstractGangTask("Partial Cleaning Task"), 3244 _is_alive(is_alive), 3245 _keep_alive(keep_alive), 3246 _phase_times(phase_times) 3247 { 3248 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3249 StringDedup::gc_prologue(true); 3250 } 3251 3252 ~G1StringDedupCleaningTask() { 3253 StringDedup::gc_epilogue(); 3254 } 3255 3256 void work(uint worker_id) { 3257 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3258 { 3259 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3260 StringDedupQueue::unlink_or_oops_do(&cl); 3261 } 3262 { 3263 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3264 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3265 } 3266 } 3267 }; 3268 3269 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3270 OopClosure* keep_alive, 3271 G1GCPhaseTimes* phase_times) { 3272 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3273 workers()->run_task(&cl); 3274 } 3275 3276 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3277 private: 3278 G1RedirtyCardsQueueSet* _qset; 3279 G1CollectedHeap* _g1h; 3280 BufferNode* volatile _nodes; 3281 3282 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) { 3283 size_t buffer_size = _qset->buffer_size(); 3284 BufferNode* next = Atomic::load(&_nodes); 3285 while (next != NULL) { 3286 BufferNode* node = next; 3287 next = Atomic::cmpxchg(&_nodes, node, node->next()); 3288 if (next == node) { 3289 cl->apply_to_buffer(node, buffer_size, worker_id); 3290 next = node->next(); 3291 } 3292 } 3293 } 3294 3295 public: 3296 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) : 3297 AbstractGangTask("Redirty Cards"), 3298 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { } 3299 3300 virtual void work(uint worker_id) { 3301 G1GCPhaseTimes* p = _g1h->phase_times(); 3302 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3303 3304 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3305 par_apply(&cl, worker_id); 3306 3307 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3308 } 3309 }; 3310 3311 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) { 3312 double redirty_logged_cards_start = os::elapsedTime(); 3313 3314 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this); 3315 workers()->run_task(&redirty_task); 3316 3317 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3318 dcq.merge_bufferlists(rdcqs); 3319 3320 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3321 } 3322 3323 // Weak Reference Processing support 3324 3325 bool G1STWIsAliveClosure::do_object_b(oop p) { 3326 // An object is reachable if it is outside the collection set, 3327 // or is inside and copied. 3328 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3329 } 3330 3331 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3332 assert(obj != NULL, "must not be NULL"); 3333 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3334 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3335 // may falsely indicate that this is not the case here: however the collection set only 3336 // contains old regions when concurrent mark is not running. 3337 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3338 } 3339 3340 // Non Copying Keep Alive closure 3341 class G1KeepAliveClosure: public OopClosure { 3342 G1CollectedHeap*_g1h; 3343 public: 3344 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3345 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3346 void do_oop(oop* p) { 3347 oop obj = *p; 3348 assert(obj != NULL, "the caller should have filtered out NULL values"); 3349 3350 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj); 3351 if (!region_attr.is_in_cset_or_humongous()) { 3352 return; 3353 } 3354 if (region_attr.is_in_cset()) { 3355 assert( obj->is_forwarded(), "invariant" ); 3356 *p = obj->forwardee(); 3357 } else { 3358 assert(!obj->is_forwarded(), "invariant" ); 3359 assert(region_attr.is_humongous(), 3360 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type()); 3361 _g1h->set_humongous_is_live(obj); 3362 } 3363 } 3364 }; 3365 3366 // Copying Keep Alive closure - can be called from both 3367 // serial and parallel code as long as different worker 3368 // threads utilize different G1ParScanThreadState instances 3369 // and different queues. 3370 3371 class G1CopyingKeepAliveClosure: public OopClosure { 3372 G1CollectedHeap* _g1h; 3373 G1ParScanThreadState* _par_scan_state; 3374 3375 public: 3376 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3377 G1ParScanThreadState* pss): 3378 _g1h(g1h), 3379 _par_scan_state(pss) 3380 {} 3381 3382 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3383 virtual void do_oop( oop* p) { do_oop_work(p); } 3384 3385 template <class T> void do_oop_work(T* p) { 3386 oop obj = RawAccess<>::oop_load(p); 3387 3388 if (_g1h->is_in_cset_or_humongous(obj)) { 3389 // If the referent object has been forwarded (either copied 3390 // to a new location or to itself in the event of an 3391 // evacuation failure) then we need to update the reference 3392 // field and, if both reference and referent are in the G1 3393 // heap, update the RSet for the referent. 3394 // 3395 // If the referent has not been forwarded then we have to keep 3396 // it alive by policy. Therefore we have copy the referent. 3397 // 3398 // When the queue is drained (after each phase of reference processing) 3399 // the object and it's followers will be copied, the reference field set 3400 // to point to the new location, and the RSet updated. 3401 _par_scan_state->push_on_queue(p); 3402 } 3403 } 3404 }; 3405 3406 // Serial drain queue closure. Called as the 'complete_gc' 3407 // closure for each discovered list in some of the 3408 // reference processing phases. 3409 3410 class G1STWDrainQueueClosure: public VoidClosure { 3411 protected: 3412 G1CollectedHeap* _g1h; 3413 G1ParScanThreadState* _par_scan_state; 3414 3415 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3416 3417 public: 3418 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3419 _g1h(g1h), 3420 _par_scan_state(pss) 3421 { } 3422 3423 void do_void() { 3424 G1ParScanThreadState* const pss = par_scan_state(); 3425 pss->trim_queue(); 3426 } 3427 }; 3428 3429 // Parallel Reference Processing closures 3430 3431 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3432 // processing during G1 evacuation pauses. 3433 3434 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3435 private: 3436 G1CollectedHeap* _g1h; 3437 G1ParScanThreadStateSet* _pss; 3438 RefToScanQueueSet* _queues; 3439 WorkGang* _workers; 3440 3441 public: 3442 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3443 G1ParScanThreadStateSet* per_thread_states, 3444 WorkGang* workers, 3445 RefToScanQueueSet *task_queues) : 3446 _g1h(g1h), 3447 _pss(per_thread_states), 3448 _queues(task_queues), 3449 _workers(workers) 3450 { 3451 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3452 } 3453 3454 // Executes the given task using concurrent marking worker threads. 3455 virtual void execute(ProcessTask& task, uint ergo_workers); 3456 }; 3457 3458 // Gang task for possibly parallel reference processing 3459 3460 class G1STWRefProcTaskProxy: public AbstractGangTask { 3461 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3462 ProcessTask& _proc_task; 3463 G1CollectedHeap* _g1h; 3464 G1ParScanThreadStateSet* _pss; 3465 RefToScanQueueSet* _task_queues; 3466 TaskTerminator* _terminator; 3467 3468 public: 3469 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3470 G1CollectedHeap* g1h, 3471 G1ParScanThreadStateSet* per_thread_states, 3472 RefToScanQueueSet *task_queues, 3473 TaskTerminator* terminator) : 3474 AbstractGangTask("Process reference objects in parallel"), 3475 _proc_task(proc_task), 3476 _g1h(g1h), 3477 _pss(per_thread_states), 3478 _task_queues(task_queues), 3479 _terminator(terminator) 3480 {} 3481 3482 virtual void work(uint worker_id) { 3483 // The reference processing task executed by a single worker. 3484 ResourceMark rm; 3485 HandleMark hm; 3486 3487 G1STWIsAliveClosure is_alive(_g1h); 3488 3489 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3490 pss->set_ref_discoverer(NULL); 3491 3492 // Keep alive closure. 3493 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3494 3495 // Complete GC closure 3496 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3497 3498 // Call the reference processing task's work routine. 3499 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3500 3501 // Note we cannot assert that the refs array is empty here as not all 3502 // of the processing tasks (specifically phase2 - pp2_work) execute 3503 // the complete_gc closure (which ordinarily would drain the queue) so 3504 // the queue may not be empty. 3505 } 3506 }; 3507 3508 // Driver routine for parallel reference processing. 3509 // Creates an instance of the ref processing gang 3510 // task and has the worker threads execute it. 3511 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3512 assert(_workers != NULL, "Need parallel worker threads."); 3513 3514 assert(_workers->active_workers() >= ergo_workers, 3515 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3516 ergo_workers, _workers->active_workers()); 3517 TaskTerminator terminator(ergo_workers, _queues); 3518 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3519 3520 _workers->run_task(&proc_task_proxy, ergo_workers); 3521 } 3522 3523 // End of weak reference support closures 3524 3525 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3526 double ref_proc_start = os::elapsedTime(); 3527 3528 ReferenceProcessor* rp = _ref_processor_stw; 3529 assert(rp->discovery_enabled(), "should have been enabled"); 3530 3531 // Closure to test whether a referent is alive. 3532 G1STWIsAliveClosure is_alive(this); 3533 3534 // Even when parallel reference processing is enabled, the processing 3535 // of JNI refs is serial and performed serially by the current thread 3536 // rather than by a worker. The following PSS will be used for processing 3537 // JNI refs. 3538 3539 // Use only a single queue for this PSS. 3540 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3541 pss->set_ref_discoverer(NULL); 3542 assert(pss->queue_is_empty(), "pre-condition"); 3543 3544 // Keep alive closure. 3545 G1CopyingKeepAliveClosure keep_alive(this, pss); 3546 3547 // Serial Complete GC closure 3548 G1STWDrainQueueClosure drain_queue(this, pss); 3549 3550 // Setup the soft refs policy... 3551 rp->setup_policy(false); 3552 3553 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3554 3555 ReferenceProcessorStats stats; 3556 if (!rp->processing_is_mt()) { 3557 // Serial reference processing... 3558 stats = rp->process_discovered_references(&is_alive, 3559 &keep_alive, 3560 &drain_queue, 3561 NULL, 3562 pt); 3563 } else { 3564 uint no_of_gc_workers = workers()->active_workers(); 3565 3566 // Parallel reference processing 3567 assert(no_of_gc_workers <= rp->max_num_queues(), 3568 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3569 no_of_gc_workers, rp->max_num_queues()); 3570 3571 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3572 stats = rp->process_discovered_references(&is_alive, 3573 &keep_alive, 3574 &drain_queue, 3575 &par_task_executor, 3576 pt); 3577 } 3578 3579 _gc_tracer_stw->report_gc_reference_stats(stats); 3580 3581 // We have completed copying any necessary live referent objects. 3582 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3583 3584 make_pending_list_reachable(); 3585 3586 assert(!rp->discovery_enabled(), "Postcondition"); 3587 rp->verify_no_references_recorded(); 3588 3589 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3590 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3591 } 3592 3593 void G1CollectedHeap::make_pending_list_reachable() { 3594 if (collector_state()->in_initial_mark_gc()) { 3595 oop pll_head = Universe::reference_pending_list(); 3596 if (pll_head != NULL) { 3597 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3598 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3599 } 3600 } 3601 } 3602 3603 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3604 Ticks start = Ticks::now(); 3605 per_thread_states->flush(); 3606 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds()); 3607 } 3608 3609 class G1PrepareEvacuationTask : public AbstractGangTask { 3610 class G1PrepareRegionsClosure : public HeapRegionClosure { 3611 G1CollectedHeap* _g1h; 3612 G1PrepareEvacuationTask* _parent_task; 3613 size_t _worker_humongous_total; 3614 size_t _worker_humongous_candidates; 3615 3616 bool humongous_region_is_candidate(HeapRegion* region) const { 3617 assert(region->is_starts_humongous(), "Must start a humongous object"); 3618 3619 oop obj = oop(region->bottom()); 3620 3621 // Dead objects cannot be eager reclaim candidates. Due to class 3622 // unloading it is unsafe to query their classes so we return early. 3623 if (_g1h->is_obj_dead(obj, region)) { 3624 return false; 3625 } 3626 3627 // If we do not have a complete remembered set for the region, then we can 3628 // not be sure that we have all references to it. 3629 if (!region->rem_set()->is_complete()) { 3630 return false; 3631 } 3632 // Candidate selection must satisfy the following constraints 3633 // while concurrent marking is in progress: 3634 // 3635 // * In order to maintain SATB invariants, an object must not be 3636 // reclaimed if it was allocated before the start of marking and 3637 // has not had its references scanned. Such an object must have 3638 // its references (including type metadata) scanned to ensure no 3639 // live objects are missed by the marking process. Objects 3640 // allocated after the start of concurrent marking don't need to 3641 // be scanned. 3642 // 3643 // * An object must not be reclaimed if it is on the concurrent 3644 // mark stack. Objects allocated after the start of concurrent 3645 // marking are never pushed on the mark stack. 3646 // 3647 // Nominating only objects allocated after the start of concurrent 3648 // marking is sufficient to meet both constraints. This may miss 3649 // some objects that satisfy the constraints, but the marking data 3650 // structures don't support efficiently performing the needed 3651 // additional tests or scrubbing of the mark stack. 3652 // 3653 // However, we presently only nominate is_typeArray() objects. 3654 // A humongous object containing references induces remembered 3655 // set entries on other regions. In order to reclaim such an 3656 // object, those remembered sets would need to be cleaned up. 3657 // 3658 // We also treat is_typeArray() objects specially, allowing them 3659 // to be reclaimed even if allocated before the start of 3660 // concurrent mark. For this we rely on mark stack insertion to 3661 // exclude is_typeArray() objects, preventing reclaiming an object 3662 // that is in the mark stack. We also rely on the metadata for 3663 // such objects to be built-in and so ensured to be kept live. 3664 // Frequent allocation and drop of large binary blobs is an 3665 // important use case for eager reclaim, and this special handling 3666 // may reduce needed headroom. 3667 3668 return obj->is_typeArray() && 3669 _g1h->is_potential_eager_reclaim_candidate(region); 3670 } 3671 3672 public: 3673 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) : 3674 _g1h(g1h), 3675 _parent_task(parent_task), 3676 _worker_humongous_total(0), 3677 _worker_humongous_candidates(0) { } 3678 3679 ~G1PrepareRegionsClosure() { 3680 _parent_task->add_humongous_candidates(_worker_humongous_candidates); 3681 _parent_task->add_humongous_total(_worker_humongous_total); 3682 } 3683 3684 virtual bool do_heap_region(HeapRegion* hr) { 3685 // First prepare the region for scanning 3686 _g1h->rem_set()->prepare_region_for_scan(hr); 3687 3688 // Now check if region is a humongous candidate 3689 if (!hr->is_starts_humongous()) { 3690 _g1h->register_region_with_region_attr(hr); 3691 return false; 3692 } 3693 3694 uint index = hr->hrm_index(); 3695 if (humongous_region_is_candidate(hr)) { 3696 _g1h->set_humongous_reclaim_candidate(index, true); 3697 _g1h->register_humongous_region_with_region_attr(index); 3698 _worker_humongous_candidates++; 3699 // We will later handle the remembered sets of these regions. 3700 } else { 3701 _g1h->set_humongous_reclaim_candidate(index, false); 3702 _g1h->register_region_with_region_attr(hr); 3703 } 3704 _worker_humongous_total++; 3705 3706 return false; 3707 } 3708 }; 3709 3710 G1CollectedHeap* _g1h; 3711 HeapRegionClaimer _claimer; 3712 volatile size_t _humongous_total; 3713 volatile size_t _humongous_candidates; 3714 public: 3715 G1PrepareEvacuationTask(G1CollectedHeap* g1h) : 3716 AbstractGangTask("Prepare Evacuation"), 3717 _g1h(g1h), 3718 _claimer(_g1h->workers()->active_workers()), 3719 _humongous_total(0), 3720 _humongous_candidates(0) { } 3721 3722 ~G1PrepareEvacuationTask() { 3723 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0); 3724 } 3725 3726 void work(uint worker_id) { 3727 G1PrepareRegionsClosure cl(_g1h, this); 3728 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id); 3729 } 3730 3731 void add_humongous_candidates(size_t candidates) { 3732 Atomic::add(&_humongous_candidates, candidates); 3733 } 3734 3735 void add_humongous_total(size_t total) { 3736 Atomic::add(&_humongous_total, total); 3737 } 3738 3739 size_t humongous_candidates() { 3740 return _humongous_candidates; 3741 } 3742 3743 size_t humongous_total() { 3744 return _humongous_total; 3745 } 3746 }; 3747 3748 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3749 _bytes_used_during_gc = 0; 3750 3751 _expand_heap_after_alloc_failure = true; 3752 _evacuation_failed = false; 3753 3754 // Disable the hot card cache. 3755 _hot_card_cache->reset_hot_cache_claimed_index(); 3756 _hot_card_cache->set_use_cache(false); 3757 3758 // Initialize the GC alloc regions. 3759 _allocator->init_gc_alloc_regions(evacuation_info); 3760 3761 { 3762 Ticks start = Ticks::now(); 3763 rem_set()->prepare_for_scan_heap_roots(); 3764 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0); 3765 } 3766 3767 { 3768 G1PrepareEvacuationTask g1_prep_task(this); 3769 Tickspan task_time = run_task(&g1_prep_task); 3770 3771 phase_times()->record_register_regions(task_time.seconds() * 1000.0, 3772 g1_prep_task.humongous_total(), 3773 g1_prep_task.humongous_candidates()); 3774 } 3775 3776 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table."); 3777 _preserved_marks_set.assert_empty(); 3778 3779 #if COMPILER2_OR_JVMCI 3780 DerivedPointerTable::clear(); 3781 #endif 3782 3783 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3784 if (collector_state()->in_initial_mark_gc()) { 3785 concurrent_mark()->pre_initial_mark(); 3786 3787 double start_clear_claimed_marks = os::elapsedTime(); 3788 3789 ClassLoaderDataGraph::clear_claimed_marks(); 3790 3791 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3792 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3793 } 3794 3795 // Should G1EvacuationFailureALot be in effect for this GC? 3796 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3797 } 3798 3799 class G1EvacuateRegionsBaseTask : public AbstractGangTask { 3800 protected: 3801 G1CollectedHeap* _g1h; 3802 G1ParScanThreadStateSet* _per_thread_states; 3803 RefToScanQueueSet* _task_queues; 3804 TaskTerminator _terminator; 3805 uint _num_workers; 3806 3807 void evacuate_live_objects(G1ParScanThreadState* pss, 3808 uint worker_id, 3809 G1GCPhaseTimes::GCParPhases objcopy_phase, 3810 G1GCPhaseTimes::GCParPhases termination_phase) { 3811 G1GCPhaseTimes* p = _g1h->phase_times(); 3812 3813 Ticks start = Ticks::now(); 3814 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase); 3815 cl.do_void(); 3816 3817 assert(pss->queue_is_empty(), "should be empty"); 3818 3819 Tickspan evac_time = (Ticks::now() - start); 3820 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time()); 3821 3822 if (termination_phase == G1GCPhaseTimes::Termination) { 3823 p->record_time_secs(termination_phase, worker_id, cl.term_time()); 3824 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3825 } else { 3826 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time()); 3827 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts()); 3828 } 3829 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation"); 3830 } 3831 3832 virtual void start_work(uint worker_id) { } 3833 3834 virtual void end_work(uint worker_id) { } 3835 3836 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0; 3837 3838 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0; 3839 3840 public: 3841 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) : 3842 AbstractGangTask(name), 3843 _g1h(G1CollectedHeap::heap()), 3844 _per_thread_states(per_thread_states), 3845 _task_queues(task_queues), 3846 _terminator(num_workers, _task_queues), 3847 _num_workers(num_workers) 3848 { } 3849 3850 void work(uint worker_id) { 3851 start_work(worker_id); 3852 3853 { 3854 ResourceMark rm; 3855 HandleMark hm; 3856 3857 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3858 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3859 3860 scan_roots(pss, worker_id); 3861 evacuate_live_objects(pss, worker_id); 3862 } 3863 3864 end_work(worker_id); 3865 } 3866 }; 3867 3868 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask { 3869 G1RootProcessor* _root_processor; 3870 3871 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3872 _root_processor->evacuate_roots(pss, worker_id); 3873 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy); 3874 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy); 3875 } 3876 3877 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3878 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination); 3879 } 3880 3881 void start_work(uint worker_id) { 3882 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds()); 3883 } 3884 3885 void end_work(uint worker_id) { 3886 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds()); 3887 } 3888 3889 public: 3890 G1EvacuateRegionsTask(G1CollectedHeap* g1h, 3891 G1ParScanThreadStateSet* per_thread_states, 3892 RefToScanQueueSet* task_queues, 3893 G1RootProcessor* root_processor, 3894 uint num_workers) : 3895 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers), 3896 _root_processor(root_processor) 3897 { } 3898 }; 3899 3900 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3901 G1GCPhaseTimes* p = phase_times(); 3902 3903 { 3904 Ticks start = Ticks::now(); 3905 rem_set()->merge_heap_roots(true /* initial_evacuation */); 3906 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3907 } 3908 3909 Tickspan task_time; 3910 const uint num_workers = workers()->active_workers(); 3911 3912 Ticks start_processing = Ticks::now(); 3913 { 3914 G1RootProcessor root_processor(this, num_workers); 3915 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers); 3916 task_time = run_task(&g1_par_task); 3917 // Closing the inner scope will execute the destructor for the G1RootProcessor object. 3918 // To extract its code root fixup time we measure total time of this scope and 3919 // subtract from the time the WorkGang task took. 3920 } 3921 Tickspan total_processing = Ticks::now() - start_processing; 3922 3923 p->record_initial_evac_time(task_time.seconds() * 1000.0); 3924 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3925 } 3926 3927 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask { 3928 3929 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3930 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy); 3931 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy); 3932 } 3933 3934 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3935 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination); 3936 } 3937 3938 public: 3939 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states, 3940 RefToScanQueueSet* queues, 3941 uint num_workers) : 3942 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) { 3943 } 3944 }; 3945 3946 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) { 3947 class G1MarkScope : public MarkScope { }; 3948 3949 Tickspan task_time; 3950 3951 Ticks start_processing = Ticks::now(); 3952 { 3953 G1MarkScope code_mark_scope; 3954 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers()); 3955 task_time = run_task(&task); 3956 // See comment in evacuate_collection_set() for the reason of the scope. 3957 } 3958 Tickspan total_processing = Ticks::now() - start_processing; 3959 3960 G1GCPhaseTimes* p = phase_times(); 3961 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0); 3962 } 3963 3964 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3965 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3966 3967 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) { 3968 3969 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3970 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3971 3972 if (time_left_ms < 0 || 3973 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) { 3974 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms", 3975 _collection_set.optional_region_length(), time_left_ms); 3976 break; 3977 } 3978 3979 { 3980 Ticks start = Ticks::now(); 3981 rem_set()->merge_heap_roots(false /* initial_evacuation */); 3982 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0); 3983 } 3984 3985 { 3986 Ticks start = Ticks::now(); 3987 evacuate_next_optional_regions(per_thread_states); 3988 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0); 3989 } 3990 } 3991 3992 _collection_set.abandon_optional_collection_set(per_thread_states); 3993 } 3994 3995 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 3996 G1RedirtyCardsQueueSet* rdcqs, 3997 G1ParScanThreadStateSet* per_thread_states) { 3998 G1GCPhaseTimes* p = phase_times(); 3999 4000 rem_set()->cleanup_after_scan_heap_roots(); 4001 4002 // Process any discovered reference objects - we have 4003 // to do this _before_ we retire the GC alloc regions 4004 // as we may have to copy some 'reachable' referent 4005 // objects (and their reachable sub-graphs) that were 4006 // not copied during the pause. 4007 process_discovered_references(per_thread_states); 4008 4009 G1STWIsAliveClosure is_alive(this); 4010 G1KeepAliveClosure keep_alive(this); 4011 4012 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times()); 4013 4014 if (G1StringDedup::is_enabled()) { 4015 double string_dedup_time_ms = os::elapsedTime(); 4016 4017 string_dedup_cleaning(&is_alive, &keep_alive, p); 4018 4019 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 4020 p->record_string_deduplication_time(string_cleanup_time_ms); 4021 } 4022 4023 _allocator->release_gc_alloc_regions(evacuation_info); 4024 4025 if (evacuation_failed()) { 4026 restore_after_evac_failure(rdcqs); 4027 4028 // Reset the G1EvacuationFailureALot counters and flags 4029 NOT_PRODUCT(reset_evacuation_should_fail();) 4030 4031 double recalculate_used_start = os::elapsedTime(); 4032 set_used(recalculate_used()); 4033 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 4034 4035 if (_archive_allocator != NULL) { 4036 _archive_allocator->clear_used(); 4037 } 4038 for (uint i = 0; i < ParallelGCThreads; i++) { 4039 if (_evacuation_failed_info_array[i].has_failed()) { 4040 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 4041 } 4042 } 4043 } else { 4044 // The "used" of the the collection set have already been subtracted 4045 // when they were freed. Add in the bytes used. 4046 increase_used(_bytes_used_during_gc); 4047 } 4048 4049 _preserved_marks_set.assert_empty(); 4050 4051 merge_per_thread_state_info(per_thread_states); 4052 4053 // Reset and re-enable the hot card cache. 4054 // Note the counts for the cards in the regions in the 4055 // collection set are reset when the collection set is freed. 4056 _hot_card_cache->reset_hot_cache(); 4057 _hot_card_cache->set_use_cache(true); 4058 4059 purge_code_root_memory(); 4060 4061 redirty_logged_cards(rdcqs); 4062 4063 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 4064 4065 eagerly_reclaim_humongous_regions(); 4066 4067 record_obj_copy_mem_stats(); 4068 4069 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 4070 evacuation_info.set_bytes_used(_bytes_used_during_gc); 4071 4072 #if COMPILER2_OR_JVMCI 4073 double start = os::elapsedTime(); 4074 DerivedPointerTable::update_pointers(); 4075 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4076 #endif 4077 policy()->print_age_table(); 4078 } 4079 4080 void G1CollectedHeap::record_obj_copy_mem_stats() { 4081 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4082 4083 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4084 create_g1_evac_summary(&_old_evac_stats)); 4085 } 4086 4087 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) { 4088 assert(!hr->is_free(), "the region should not be free"); 4089 assert(!hr->is_empty(), "the region should not be empty"); 4090 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4091 4092 if (G1VerifyBitmaps) { 4093 MemRegion mr(hr->bottom(), hr->end()); 4094 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4095 } 4096 4097 // Clear the card counts for this region. 4098 // Note: we only need to do this if the region is not young 4099 // (since we don't refine cards in young regions). 4100 if (!hr->is_young()) { 4101 _hot_card_cache->reset_card_counts(hr); 4102 } 4103 4104 // Reset region metadata to allow reuse. 4105 hr->hr_clear(true /* clear_space */); 4106 _policy->remset_tracker()->update_at_free(hr); 4107 4108 if (free_list != NULL) { 4109 free_list->add_ordered(hr); 4110 } 4111 } 4112 4113 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4114 FreeRegionList* free_list) { 4115 assert(hr->is_humongous(), "this is only for humongous regions"); 4116 assert(free_list != NULL, "pre-condition"); 4117 hr->clear_humongous(); 4118 free_region(hr, free_list); 4119 } 4120 4121 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4122 const uint humongous_regions_removed) { 4123 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4124 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4125 _old_set.bulk_remove(old_regions_removed); 4126 _humongous_set.bulk_remove(humongous_regions_removed); 4127 } 4128 4129 } 4130 4131 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4132 assert(list != NULL, "list can't be null"); 4133 if (!list->is_empty()) { 4134 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4135 _hrm->insert_list_into_free_list(list); 4136 } 4137 } 4138 4139 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4140 decrease_used(bytes); 4141 } 4142 4143 class G1FreeCollectionSetTask : public AbstractGangTask { 4144 // Helper class to keep statistics for the collection set freeing 4145 class FreeCSetStats { 4146 size_t _before_used_bytes; // Usage in regions successfully evacutate 4147 size_t _after_used_bytes; // Usage in regions failing evacuation 4148 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old 4149 size_t _failure_used_words; // Live size in failed regions 4150 size_t _failure_waste_words; // Wasted size in failed regions 4151 size_t _rs_length; // Remembered set size 4152 uint _regions_freed; // Number of regions freed 4153 public: 4154 FreeCSetStats() : 4155 _before_used_bytes(0), 4156 _after_used_bytes(0), 4157 _bytes_allocated_in_old_since_last_gc(0), 4158 _failure_used_words(0), 4159 _failure_waste_words(0), 4160 _rs_length(0), 4161 _regions_freed(0) { } 4162 4163 void merge_stats(FreeCSetStats* other) { 4164 assert(other != NULL, "invariant"); 4165 _before_used_bytes += other->_before_used_bytes; 4166 _after_used_bytes += other->_after_used_bytes; 4167 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc; 4168 _failure_used_words += other->_failure_used_words; 4169 _failure_waste_words += other->_failure_waste_words; 4170 _rs_length += other->_rs_length; 4171 _regions_freed += other->_regions_freed; 4172 } 4173 4174 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) { 4175 evacuation_info->set_regions_freed(_regions_freed); 4176 evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4177 4178 g1h->decrement_summary_bytes(_before_used_bytes); 4179 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4180 4181 G1Policy *policy = g1h->policy(); 4182 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4183 policy->record_rs_length(_rs_length); 4184 policy->cset_regions_freed(); 4185 } 4186 4187 void account_failed_region(HeapRegion* r) { 4188 size_t used_words = r->marked_bytes() / HeapWordSize; 4189 _failure_used_words += used_words; 4190 _failure_waste_words += HeapRegion::GrainWords - used_words; 4191 _after_used_bytes += r->used(); 4192 4193 // When moving a young gen region to old gen, we "allocate" that whole 4194 // region there. This is in addition to any already evacuated objects. 4195 // Notify the policy about that. Old gen regions do not cause an 4196 // additional allocation: both the objects still in the region and the 4197 // ones already moved are accounted for elsewhere. 4198 if (r->is_young()) { 4199 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4200 } 4201 } 4202 4203 void account_evacuated_region(HeapRegion* r) { 4204 _before_used_bytes += r->used(); 4205 _regions_freed += 1; 4206 } 4207 4208 void account_rs_length(HeapRegion* r) { 4209 _rs_length += r->rem_set()->occupied(); 4210 } 4211 }; 4212 4213 // Closure applied to all regions in the collection set. 4214 class FreeCSetClosure : public HeapRegionClosure { 4215 // Helper to send JFR events for regions. 4216 class JFREventForRegion { 4217 EventGCPhaseParallel _event; 4218 public: 4219 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() { 4220 _event.set_gcId(GCId::current()); 4221 _event.set_gcWorkerId(worker_id); 4222 if (region->is_young()) { 4223 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4224 } else { 4225 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4226 } 4227 } 4228 4229 ~JFREventForRegion() { 4230 _event.commit(); 4231 } 4232 }; 4233 4234 // Helper to do timing for region work. 4235 class TimerForRegion { 4236 Tickspan& _time; 4237 Ticks _start_time; 4238 public: 4239 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { } 4240 ~TimerForRegion() { 4241 _time += Ticks::now() - _start_time; 4242 } 4243 }; 4244 4245 // FreeCSetClosure members 4246 G1CollectedHeap* _g1h; 4247 const size_t* _surviving_young_words; 4248 uint _worker_id; 4249 Tickspan _young_time; 4250 Tickspan _non_young_time; 4251 FreeCSetStats* _stats; 4252 4253 void assert_in_cset(HeapRegion* r) { 4254 assert(r->young_index_in_cset() != 0 && 4255 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(), 4256 "Young index %u is wrong for region %u of type %s with %u young regions", 4257 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length()); 4258 } 4259 4260 void handle_evacuated_region(HeapRegion* r) { 4261 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4262 stats()->account_evacuated_region(r); 4263 4264 // Free the region and and its remembered set. 4265 _g1h->free_region(r, NULL); 4266 } 4267 4268 void handle_failed_region(HeapRegion* r) { 4269 // Do some allocation statistics accounting. Regions that failed evacuation 4270 // are always made old, so there is no need to update anything in the young 4271 // gen statistics, but we need to update old gen statistics. 4272 stats()->account_failed_region(r); 4273 4274 // Update the region state due to the failed evacuation. 4275 r->handle_evacuation_failure(); 4276 4277 // Add region to old set, need to hold lock. 4278 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4279 _g1h->old_set_add(r); 4280 } 4281 4282 Tickspan& timer_for_region(HeapRegion* r) { 4283 return r->is_young() ? _young_time : _non_young_time; 4284 } 4285 4286 FreeCSetStats* stats() { 4287 return _stats; 4288 } 4289 public: 4290 FreeCSetClosure(const size_t* surviving_young_words, 4291 uint worker_id, 4292 FreeCSetStats* stats) : 4293 HeapRegionClosure(), 4294 _g1h(G1CollectedHeap::heap()), 4295 _surviving_young_words(surviving_young_words), 4296 _worker_id(worker_id), 4297 _young_time(), 4298 _non_young_time(), 4299 _stats(stats) { } 4300 4301 virtual bool do_heap_region(HeapRegion* r) { 4302 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index()); 4303 JFREventForRegion event(r, _worker_id); 4304 TimerForRegion timer(timer_for_region(r)); 4305 4306 _g1h->clear_region_attr(r); 4307 stats()->account_rs_length(r); 4308 4309 if (r->is_young()) { 4310 assert_in_cset(r); 4311 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]); 4312 } 4313 4314 if (r->evacuation_failed()) { 4315 handle_failed_region(r); 4316 } else { 4317 handle_evacuated_region(r); 4318 } 4319 assert(!_g1h->is_on_master_free_list(r), "sanity"); 4320 4321 return false; 4322 } 4323 4324 void report_timing(Tickspan parallel_time) { 4325 G1GCPhaseTimes* pt = _g1h->phase_times(); 4326 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds()); 4327 if (_young_time.value() > 0) { 4328 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds()); 4329 } 4330 if (_non_young_time.value() > 0) { 4331 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds()); 4332 } 4333 } 4334 }; 4335 4336 // G1FreeCollectionSetTask members 4337 G1CollectedHeap* _g1h; 4338 G1EvacuationInfo* _evacuation_info; 4339 FreeCSetStats* _worker_stats; 4340 HeapRegionClaimer _claimer; 4341 const size_t* _surviving_young_words; 4342 uint _active_workers; 4343 4344 FreeCSetStats* worker_stats(uint worker) { 4345 return &_worker_stats[worker]; 4346 } 4347 4348 void report_statistics() { 4349 // Merge the accounting 4350 FreeCSetStats total_stats; 4351 for (uint worker = 0; worker < _active_workers; worker++) { 4352 total_stats.merge_stats(worker_stats(worker)); 4353 } 4354 total_stats.report(_g1h, _evacuation_info); 4355 } 4356 4357 public: 4358 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) : 4359 AbstractGangTask("G1 Free Collection Set"), 4360 _g1h(G1CollectedHeap::heap()), 4361 _evacuation_info(evacuation_info), 4362 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)), 4363 _claimer(active_workers), 4364 _surviving_young_words(surviving_young_words), 4365 _active_workers(active_workers) { 4366 for (uint worker = 0; worker < active_workers; worker++) { 4367 ::new (&_worker_stats[worker]) FreeCSetStats(); 4368 } 4369 } 4370 4371 ~G1FreeCollectionSetTask() { 4372 Ticks serial_time = Ticks::now(); 4373 report_statistics(); 4374 for (uint worker = 0; worker < _active_workers; worker++) { 4375 _worker_stats[worker].~FreeCSetStats(); 4376 } 4377 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats); 4378 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0); 4379 } 4380 4381 virtual void work(uint worker_id) { 4382 EventGCPhaseParallel event; 4383 Ticks start = Ticks::now(); 4384 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id)); 4385 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id); 4386 4387 // Report the total parallel time along with some more detailed metrics. 4388 cl.report_timing(Ticks::now() - start); 4389 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet)); 4390 } 4391 }; 4392 4393 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4394 _eden.clear(); 4395 4396 // The free collections set is split up in two tasks, the first 4397 // frees the collection set and records what regions are free, 4398 // and the second one rebuilds the free list. This proved to be 4399 // more efficient than adding a sorted list to another. 4400 4401 Ticks free_cset_start_time = Ticks::now(); 4402 { 4403 uint const num_cs_regions = _collection_set.region_length(); 4404 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers()); 4405 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers); 4406 4407 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)", 4408 cl.name(), num_workers, num_cs_regions, num_regions()); 4409 workers()->run_task(&cl, num_workers); 4410 } 4411 4412 Ticks free_cset_end_time = Ticks::now(); 4413 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0); 4414 4415 // Now rebuild the free region list. 4416 hrm()->rebuild_free_list(workers()); 4417 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0); 4418 4419 collection_set->clear(); 4420 } 4421 4422 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4423 private: 4424 FreeRegionList* _free_region_list; 4425 HeapRegionSet* _proxy_set; 4426 uint _humongous_objects_reclaimed; 4427 uint _humongous_regions_reclaimed; 4428 size_t _freed_bytes; 4429 public: 4430 4431 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4432 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4433 } 4434 4435 virtual bool do_heap_region(HeapRegion* r) { 4436 if (!r->is_starts_humongous()) { 4437 return false; 4438 } 4439 4440 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4441 4442 oop obj = (oop)r->bottom(); 4443 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4444 4445 // The following checks whether the humongous object is live are sufficient. 4446 // The main additional check (in addition to having a reference from the roots 4447 // or the young gen) is whether the humongous object has a remembered set entry. 4448 // 4449 // A humongous object cannot be live if there is no remembered set for it 4450 // because: 4451 // - there can be no references from within humongous starts regions referencing 4452 // the object because we never allocate other objects into them. 4453 // (I.e. there are no intra-region references that may be missed by the 4454 // remembered set) 4455 // - as soon there is a remembered set entry to the humongous starts region 4456 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4457 // until the end of a concurrent mark. 4458 // 4459 // It is not required to check whether the object has been found dead by marking 4460 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4461 // all objects allocated during that time are considered live. 4462 // SATB marking is even more conservative than the remembered set. 4463 // So if at this point in the collection there is no remembered set entry, 4464 // nobody has a reference to it. 4465 // At the start of collection we flush all refinement logs, and remembered sets 4466 // are completely up-to-date wrt to references to the humongous object. 4467 // 4468 // Other implementation considerations: 4469 // - never consider object arrays at this time because they would pose 4470 // considerable effort for cleaning up the the remembered sets. This is 4471 // required because stale remembered sets might reference locations that 4472 // are currently allocated into. 4473 uint region_idx = r->hrm_index(); 4474 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4475 !r->rem_set()->is_empty()) { 4476 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", 4477 region_idx, 4478 (size_t)obj->size() * HeapWordSize, 4479 p2i(r->bottom()), 4480 r->rem_set()->occupied(), 4481 r->rem_set()->strong_code_roots_list_length(), 4482 next_bitmap->is_marked(r->bottom()), 4483 g1h->is_humongous_reclaim_candidate(region_idx), 4484 obj->is_typeArray() 4485 ); 4486 return false; 4487 } 4488 4489 guarantee(obj->is_typeArray(), 4490 "Only eagerly reclaiming type arrays is supported, but the object " 4491 PTR_FORMAT " is not.", p2i(r->bottom())); 4492 4493 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", 4494 region_idx, 4495 (size_t)obj->size() * HeapWordSize, 4496 p2i(r->bottom()), 4497 r->rem_set()->occupied(), 4498 r->rem_set()->strong_code_roots_list_length(), 4499 next_bitmap->is_marked(r->bottom()), 4500 g1h->is_humongous_reclaim_candidate(region_idx), 4501 obj->is_typeArray() 4502 ); 4503 4504 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4505 cm->humongous_object_eagerly_reclaimed(r); 4506 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4507 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4508 region_idx, 4509 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4510 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4511 _humongous_objects_reclaimed++; 4512 do { 4513 HeapRegion* next = g1h->next_region_in_humongous(r); 4514 _freed_bytes += r->used(); 4515 r->set_containing_set(NULL); 4516 _humongous_regions_reclaimed++; 4517 g1h->free_humongous_region(r, _free_region_list); 4518 r = next; 4519 } while (r != NULL); 4520 4521 return false; 4522 } 4523 4524 uint humongous_objects_reclaimed() { 4525 return _humongous_objects_reclaimed; 4526 } 4527 4528 uint humongous_regions_reclaimed() { 4529 return _humongous_regions_reclaimed; 4530 } 4531 4532 size_t bytes_freed() const { 4533 return _freed_bytes; 4534 } 4535 }; 4536 4537 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4538 assert_at_safepoint_on_vm_thread(); 4539 4540 if (!G1EagerReclaimHumongousObjects || 4541 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4542 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4543 return; 4544 } 4545 4546 double start_time = os::elapsedTime(); 4547 4548 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4549 4550 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4551 heap_region_iterate(&cl); 4552 4553 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4554 4555 G1HRPrinter* hrp = hr_printer(); 4556 if (hrp->is_active()) { 4557 FreeRegionListIterator iter(&local_cleanup_list); 4558 while (iter.more_available()) { 4559 HeapRegion* hr = iter.get_next(); 4560 hrp->cleanup(hr); 4561 } 4562 } 4563 4564 prepend_to_freelist(&local_cleanup_list); 4565 decrement_summary_bytes(cl.bytes_freed()); 4566 4567 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4568 cl.humongous_objects_reclaimed()); 4569 } 4570 4571 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4572 public: 4573 virtual bool do_heap_region(HeapRegion* r) { 4574 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4575 G1CollectedHeap::heap()->clear_region_attr(r); 4576 r->clear_young_index_in_cset(); 4577 return false; 4578 } 4579 }; 4580 4581 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4582 G1AbandonCollectionSetClosure cl; 4583 collection_set_iterate_all(&cl); 4584 4585 collection_set->clear(); 4586 collection_set->stop_incremental_building(); 4587 } 4588 4589 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4590 return _allocator->is_retained_old_region(hr); 4591 } 4592 4593 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4594 _eden.add(hr); 4595 _policy->set_region_eden(hr); 4596 } 4597 4598 #ifdef ASSERT 4599 4600 class NoYoungRegionsClosure: public HeapRegionClosure { 4601 private: 4602 bool _success; 4603 public: 4604 NoYoungRegionsClosure() : _success(true) { } 4605 bool do_heap_region(HeapRegion* r) { 4606 if (r->is_young()) { 4607 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4608 p2i(r->bottom()), p2i(r->end())); 4609 _success = false; 4610 } 4611 return false; 4612 } 4613 bool success() { return _success; } 4614 }; 4615 4616 bool G1CollectedHeap::check_young_list_empty() { 4617 bool ret = (young_regions_count() == 0); 4618 4619 NoYoungRegionsClosure closure; 4620 heap_region_iterate(&closure); 4621 ret = ret && closure.success(); 4622 4623 return ret; 4624 } 4625 4626 #endif // ASSERT 4627 4628 class TearDownRegionSetsClosure : public HeapRegionClosure { 4629 HeapRegionSet *_old_set; 4630 4631 public: 4632 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4633 4634 bool do_heap_region(HeapRegion* r) { 4635 if (r->is_old()) { 4636 _old_set->remove(r); 4637 } else if(r->is_young()) { 4638 r->uninstall_surv_rate_group(); 4639 } else { 4640 // We ignore free regions, we'll empty the free list afterwards. 4641 // We ignore humongous and archive regions, we're not tearing down these 4642 // sets. 4643 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4644 "it cannot be another type"); 4645 } 4646 return false; 4647 } 4648 4649 ~TearDownRegionSetsClosure() { 4650 assert(_old_set->is_empty(), "post-condition"); 4651 } 4652 }; 4653 4654 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4655 assert_at_safepoint_on_vm_thread(); 4656 4657 if (!free_list_only) { 4658 TearDownRegionSetsClosure cl(&_old_set); 4659 heap_region_iterate(&cl); 4660 4661 // Note that emptying the _young_list is postponed and instead done as 4662 // the first step when rebuilding the regions sets again. The reason for 4663 // this is that during a full GC string deduplication needs to know if 4664 // a collected region was young or old when the full GC was initiated. 4665 } 4666 _hrm->remove_all_free_regions(); 4667 } 4668 4669 void G1CollectedHeap::increase_used(size_t bytes) { 4670 _summary_bytes_used += bytes; 4671 } 4672 4673 void G1CollectedHeap::decrease_used(size_t bytes) { 4674 assert(_summary_bytes_used >= bytes, 4675 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4676 _summary_bytes_used, bytes); 4677 _summary_bytes_used -= bytes; 4678 } 4679 4680 void G1CollectedHeap::set_used(size_t bytes) { 4681 _summary_bytes_used = bytes; 4682 } 4683 4684 class RebuildRegionSetsClosure : public HeapRegionClosure { 4685 private: 4686 bool _free_list_only; 4687 4688 HeapRegionSet* _old_set; 4689 HeapRegionManager* _hrm; 4690 4691 size_t _total_used; 4692 4693 public: 4694 RebuildRegionSetsClosure(bool free_list_only, 4695 HeapRegionSet* old_set, 4696 HeapRegionManager* hrm) : 4697 _free_list_only(free_list_only), 4698 _old_set(old_set), _hrm(hrm), _total_used(0) { 4699 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4700 if (!free_list_only) { 4701 assert(_old_set->is_empty(), "pre-condition"); 4702 } 4703 } 4704 4705 bool do_heap_region(HeapRegion* r) { 4706 if (r->is_empty()) { 4707 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4708 // Add free regions to the free list 4709 r->set_free(); 4710 _hrm->insert_into_free_list(r); 4711 } else if (!_free_list_only) { 4712 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4713 4714 if (r->is_archive() || r->is_humongous()) { 4715 // We ignore archive and humongous regions. We left these sets unchanged. 4716 } else { 4717 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4718 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4719 r->move_to_old(); 4720 _old_set->add(r); 4721 } 4722 _total_used += r->used(); 4723 } 4724 4725 return false; 4726 } 4727 4728 size_t total_used() { 4729 return _total_used; 4730 } 4731 }; 4732 4733 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4734 assert_at_safepoint_on_vm_thread(); 4735 4736 if (!free_list_only) { 4737 _eden.clear(); 4738 _survivor.clear(); 4739 } 4740 4741 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4742 heap_region_iterate(&cl); 4743 4744 if (!free_list_only) { 4745 set_used(cl.total_used()); 4746 if (_archive_allocator != NULL) { 4747 _archive_allocator->clear_used(); 4748 } 4749 } 4750 assert_used_and_recalculate_used_equal(this); 4751 } 4752 4753 // Methods for the mutator alloc region 4754 4755 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4756 bool force, 4757 uint node_index) { 4758 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4759 bool should_allocate = policy()->should_allocate_mutator_region(); 4760 if (force || should_allocate) { 4761 HeapRegion* new_alloc_region = new_region(word_size, 4762 HeapRegionType::Eden, 4763 false /* do_expand */, 4764 node_index); 4765 if (new_alloc_region != NULL) { 4766 set_region_short_lived_locked(new_alloc_region); 4767 _hr_printer.alloc(new_alloc_region, !should_allocate); 4768 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4769 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4770 return new_alloc_region; 4771 } 4772 } 4773 return NULL; 4774 } 4775 4776 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4777 size_t allocated_bytes) { 4778 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4779 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4780 4781 collection_set()->add_eden_region(alloc_region); 4782 increase_used(allocated_bytes); 4783 _eden.add_used_bytes(allocated_bytes); 4784 _hr_printer.retire(alloc_region); 4785 4786 // We update the eden sizes here, when the region is retired, 4787 // instead of when it's allocated, since this is the point that its 4788 // used space has been recorded in _summary_bytes_used. 4789 g1mm()->update_eden_size(); 4790 } 4791 4792 // Methods for the GC alloc regions 4793 4794 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) { 4795 if (dest.is_old()) { 4796 return true; 4797 } else { 4798 return survivor_regions_count() < policy()->max_survivor_regions(); 4799 } 4800 } 4801 4802 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) { 4803 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4804 4805 if (!has_more_regions(dest)) { 4806 return NULL; 4807 } 4808 4809 HeapRegionType type; 4810 if (dest.is_young()) { 4811 type = HeapRegionType::Survivor; 4812 } else { 4813 type = HeapRegionType::Old; 4814 } 4815 4816 HeapRegion* new_alloc_region = new_region(word_size, 4817 type, 4818 true /* do_expand */, 4819 node_index); 4820 4821 if (new_alloc_region != NULL) { 4822 if (type.is_survivor()) { 4823 new_alloc_region->set_survivor(); 4824 _survivor.add(new_alloc_region); 4825 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4826 } else { 4827 new_alloc_region->set_old(); 4828 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4829 } 4830 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4831 register_region_with_region_attr(new_alloc_region); 4832 _hr_printer.alloc(new_alloc_region); 4833 return new_alloc_region; 4834 } 4835 return NULL; 4836 } 4837 4838 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4839 size_t allocated_bytes, 4840 G1HeapRegionAttr dest) { 4841 _bytes_used_during_gc += allocated_bytes; 4842 if (dest.is_old()) { 4843 old_set_add(alloc_region); 4844 } else { 4845 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type()); 4846 _survivor.add_used_bytes(allocated_bytes); 4847 } 4848 4849 bool const during_im = collector_state()->in_initial_mark_gc(); 4850 if (during_im && allocated_bytes > 0) { 4851 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top()); 4852 } 4853 _hr_printer.retire(alloc_region); 4854 } 4855 4856 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4857 bool expanded = false; 4858 uint index = _hrm->find_highest_free(&expanded); 4859 4860 if (index != G1_NO_HRM_INDEX) { 4861 if (expanded) { 4862 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4863 HeapRegion::GrainWords * HeapWordSize); 4864 } 4865 return _hrm->allocate_free_regions_starting_at(index, 1); 4866 } 4867 return NULL; 4868 } 4869 4870 // Optimized nmethod scanning 4871 4872 class RegisterNMethodOopClosure: public OopClosure { 4873 G1CollectedHeap* _g1h; 4874 nmethod* _nm; 4875 4876 template <class T> void do_oop_work(T* p) { 4877 T heap_oop = RawAccess<>::oop_load(p); 4878 if (!CompressedOops::is_null(heap_oop)) { 4879 oop obj = CompressedOops::decode_not_null(heap_oop); 4880 HeapRegion* hr = _g1h->heap_region_containing(obj); 4881 assert(!hr->is_continues_humongous(), 4882 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4883 " starting at " HR_FORMAT, 4884 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4885 4886 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4887 hr->add_strong_code_root_locked(_nm); 4888 } 4889 } 4890 4891 public: 4892 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4893 _g1h(g1h), _nm(nm) {} 4894 4895 void do_oop(oop* p) { do_oop_work(p); } 4896 void do_oop(narrowOop* p) { do_oop_work(p); } 4897 }; 4898 4899 class UnregisterNMethodOopClosure: public OopClosure { 4900 G1CollectedHeap* _g1h; 4901 nmethod* _nm; 4902 4903 template <class T> void do_oop_work(T* p) { 4904 T heap_oop = RawAccess<>::oop_load(p); 4905 if (!CompressedOops::is_null(heap_oop)) { 4906 oop obj = CompressedOops::decode_not_null(heap_oop); 4907 HeapRegion* hr = _g1h->heap_region_containing(obj); 4908 assert(!hr->is_continues_humongous(), 4909 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4910 " starting at " HR_FORMAT, 4911 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4912 4913 hr->remove_strong_code_root(_nm); 4914 } 4915 } 4916 4917 public: 4918 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4919 _g1h(g1h), _nm(nm) {} 4920 4921 void do_oop(oop* p) { do_oop_work(p); } 4922 void do_oop(narrowOop* p) { do_oop_work(p); } 4923 }; 4924 4925 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4926 guarantee(nm != NULL, "sanity"); 4927 RegisterNMethodOopClosure reg_cl(this, nm); 4928 nm->oops_do(®_cl); 4929 } 4930 4931 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4932 guarantee(nm != NULL, "sanity"); 4933 UnregisterNMethodOopClosure reg_cl(this, nm); 4934 nm->oops_do(®_cl, true); 4935 } 4936 4937 void G1CollectedHeap::purge_code_root_memory() { 4938 double purge_start = os::elapsedTime(); 4939 G1CodeRootSet::purge(); 4940 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4941 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4942 } 4943 4944 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4945 G1CollectedHeap* _g1h; 4946 4947 public: 4948 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4949 _g1h(g1h) {} 4950 4951 void do_code_blob(CodeBlob* cb) { 4952 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4953 if (nm == NULL) { 4954 return; 4955 } 4956 4957 _g1h->register_nmethod(nm); 4958 } 4959 }; 4960 4961 void G1CollectedHeap::rebuild_strong_code_roots() { 4962 RebuildStrongCodeRootClosure blob_cl(this); 4963 CodeCache::blobs_do(&blob_cl); 4964 } 4965 4966 void G1CollectedHeap::initialize_serviceability() { 4967 _g1mm->initialize_serviceability(); 4968 } 4969 4970 MemoryUsage G1CollectedHeap::memory_usage() { 4971 return _g1mm->memory_usage(); 4972 } 4973 4974 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4975 return _g1mm->memory_managers(); 4976 } 4977 4978 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4979 return _g1mm->memory_pools(); 4980 }