1 /* 2 * Copyright (c) 2001, 2019, 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/g1BarrierSet.hpp" 33 #include "gc/g1/g1CollectedHeap.inline.hpp" 34 #include "gc/g1/g1CollectionSet.hpp" 35 #include "gc/g1/g1CollectorPolicy.hpp" 36 #include "gc/g1/g1CollectorState.hpp" 37 #include "gc/g1/g1ConcurrentRefine.hpp" 38 #include "gc/g1/g1ConcurrentRefineThread.hpp" 39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 40 #include "gc/g1/g1EvacStats.inline.hpp" 41 #include "gc/g1/g1FullCollector.hpp" 42 #include "gc/g1/g1GCPhaseTimes.hpp" 43 #include "gc/g1/g1HeapSizingPolicy.hpp" 44 #include "gc/g1/g1HeapTransition.hpp" 45 #include "gc/g1/g1HeapVerifier.hpp" 46 #include "gc/g1/g1HotCardCache.hpp" 47 #include "gc/g1/g1MemoryPool.hpp" 48 #include "gc/g1/g1OopClosures.inline.hpp" 49 #include "gc/g1/g1ParScanThreadState.inline.hpp" 50 #include "gc/g1/g1Policy.hpp" 51 #include "gc/g1/g1RegionToSpaceMapper.hpp" 52 #include "gc/g1/g1RemSet.hpp" 53 #include "gc/g1/g1RootClosures.hpp" 54 #include "gc/g1/g1RootProcessor.hpp" 55 #include "gc/g1/g1SATBMarkQueueSet.hpp" 56 #include "gc/g1/g1StringDedup.hpp" 57 #include "gc/g1/g1ThreadLocalData.hpp" 58 #include "gc/g1/g1YCTypes.hpp" 59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 60 #include "gc/g1/g1VMOperations.hpp" 61 #include "gc/g1/heapRegion.inline.hpp" 62 #include "gc/g1/heapRegionRemSet.hpp" 63 #include "gc/g1/heapRegionSet.inline.hpp" 64 #include "gc/shared/gcBehaviours.hpp" 65 #include "gc/shared/gcHeapSummary.hpp" 66 #include "gc/shared/gcId.hpp" 67 #include "gc/shared/gcLocker.hpp" 68 #include "gc/shared/gcTimer.hpp" 69 #include "gc/shared/gcTrace.hpp" 70 #include "gc/shared/gcTraceTime.inline.hpp" 71 #include "gc/shared/generationSpec.hpp" 72 #include "gc/shared/isGCActiveMark.hpp" 73 #include "gc/shared/oopStorageParState.hpp" 74 #include "gc/shared/parallelCleaning.hpp" 75 #include "gc/shared/preservedMarks.inline.hpp" 76 #include "gc/shared/suspendibleThreadSet.hpp" 77 #include "gc/shared/referenceProcessor.inline.hpp" 78 #include "gc/shared/taskqueue.inline.hpp" 79 #include "gc/shared/weakProcessor.inline.hpp" 80 #include "gc/shared/workerPolicy.hpp" 81 #include "logging/log.hpp" 82 #include "memory/allocation.hpp" 83 #include "memory/iterator.hpp" 84 #include "memory/resourceArea.hpp" 85 #include "oops/access.inline.hpp" 86 #include "oops/compressedOops.inline.hpp" 87 #include "oops/oop.inline.hpp" 88 #include "runtime/atomic.hpp" 89 #include "runtime/flags/flagSetting.hpp" 90 #include "runtime/handles.inline.hpp" 91 #include "runtime/init.hpp" 92 #include "runtime/orderAccess.hpp" 93 #include "runtime/threadSMR.hpp" 94 #include "runtime/vmThread.hpp" 95 #include "utilities/align.hpp" 96 #include "utilities/globalDefinitions.hpp" 97 #include "utilities/stack.inline.hpp" 98 99 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 100 101 // INVARIANTS/NOTES 102 // 103 // All allocation activity covered by the G1CollectedHeap interface is 104 // serialized by acquiring the HeapLock. This happens in mem_allocate 105 // and allocate_new_tlab, which are the "entry" points to the 106 // allocation code from the rest of the JVM. (Note that this does not 107 // apply to TLAB allocation, which is not part of this interface: it 108 // is done by clients of this interface.) 109 110 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 111 private: 112 size_t _num_dirtied; 113 G1CollectedHeap* _g1h; 114 G1CardTable* _g1_ct; 115 116 HeapRegion* region_for_card(jbyte* card_ptr) const { 117 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 118 } 119 120 bool will_become_free(HeapRegion* hr) const { 121 // A region will be freed by free_collection_set if the region is in the 122 // collection set and has not had an evacuation failure. 123 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 124 } 125 126 public: 127 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 128 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 129 130 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 131 HeapRegion* hr = region_for_card(card_ptr); 132 133 // Should only dirty cards in regions that won't be freed. 134 if (!will_become_free(hr)) { 135 *card_ptr = G1CardTable::dirty_card_val(); 136 _num_dirtied++; 137 } 138 139 return true; 140 } 141 142 size_t num_dirtied() const { return _num_dirtied; } 143 }; 144 145 146 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 147 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 148 } 149 150 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 151 // The from card cache is not the memory that is actually committed. So we cannot 152 // take advantage of the zero_filled parameter. 153 reset_from_card_cache(start_idx, num_regions); 154 } 155 156 157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 158 MemRegion mr) { 159 return new HeapRegion(hrs_index, bot(), mr); 160 } 161 162 // Private methods. 163 164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) { 165 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 166 "the only time we use this to allocate a humongous region is " 167 "when we are allocating a single humongous region"); 168 169 HeapRegion* res = _hrm->allocate_free_region(type); 170 171 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 172 // Currently, only attempts to allocate GC alloc regions set 173 // do_expand to true. So, we should only reach here during a 174 // safepoint. If this assumption changes we might have to 175 // reconsider the use of _expand_heap_after_alloc_failure. 176 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 177 178 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 179 word_size * HeapWordSize); 180 181 if (expand(word_size * HeapWordSize)) { 182 // Given that expand() succeeded in expanding the heap, and we 183 // always expand the heap by an amount aligned to the heap 184 // region size, the free list should in theory not be empty. 185 // In either case allocate_free_region() will check for NULL. 186 res = _hrm->allocate_free_region(type); 187 } else { 188 _expand_heap_after_alloc_failure = false; 189 } 190 } 191 return res; 192 } 193 194 HeapWord* 195 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 196 uint num_regions, 197 size_t word_size) { 198 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 199 assert(is_humongous(word_size), "word_size should be humongous"); 200 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 201 202 // Index of last region in the series. 203 uint last = first + num_regions - 1; 204 205 // We need to initialize the region(s) we just discovered. This is 206 // a bit tricky given that it can happen concurrently with 207 // refinement threads refining cards on these regions and 208 // potentially wanting to refine the BOT as they are scanning 209 // those cards (this can happen shortly after a cleanup; see CR 210 // 6991377). So we have to set up the region(s) carefully and in 211 // a specific order. 212 213 // The word size sum of all the regions we will allocate. 214 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 215 assert(word_size <= word_size_sum, "sanity"); 216 217 // This will be the "starts humongous" region. 218 HeapRegion* first_hr = region_at(first); 219 // The header of the new object will be placed at the bottom of 220 // the first region. 221 HeapWord* new_obj = first_hr->bottom(); 222 // This will be the new top of the new object. 223 HeapWord* obj_top = new_obj + word_size; 224 225 // First, we need to zero the header of the space that we will be 226 // allocating. When we update top further down, some refinement 227 // threads might try to scan the region. By zeroing the header we 228 // ensure that any thread that will try to scan the region will 229 // come across the zero klass word and bail out. 230 // 231 // NOTE: It would not have been correct to have used 232 // CollectedHeap::fill_with_object() and make the space look like 233 // an int array. The thread that is doing the allocation will 234 // later update the object header to a potentially different array 235 // type and, for a very short period of time, the klass and length 236 // fields will be inconsistent. This could cause a refinement 237 // thread to calculate the object size incorrectly. 238 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 239 240 // Next, pad out the unused tail of the last region with filler 241 // objects, for improved usage accounting. 242 // How many words we use for filler objects. 243 size_t word_fill_size = word_size_sum - word_size; 244 245 // How many words memory we "waste" which cannot hold a filler object. 246 size_t words_not_fillable = 0; 247 248 if (word_fill_size >= min_fill_size()) { 249 fill_with_objects(obj_top, word_fill_size); 250 } else if (word_fill_size > 0) { 251 // We have space to fill, but we cannot fit an object there. 252 words_not_fillable = word_fill_size; 253 word_fill_size = 0; 254 } 255 256 // We will set up the first region as "starts humongous". This 257 // will also update the BOT covering all the regions to reflect 258 // that there is a single object that starts at the bottom of the 259 // first region. 260 first_hr->set_starts_humongous(obj_top, word_fill_size); 261 _g1_policy->remset_tracker()->update_at_allocate(first_hr); 262 // Then, if there are any, we will set up the "continues 263 // humongous" regions. 264 HeapRegion* hr = NULL; 265 for (uint i = first + 1; i <= last; ++i) { 266 hr = region_at(i); 267 hr->set_continues_humongous(first_hr); 268 _g1_policy->remset_tracker()->update_at_allocate(hr); 269 } 270 271 // Up to this point no concurrent thread would have been able to 272 // do any scanning on any region in this series. All the top 273 // fields still point to bottom, so the intersection between 274 // [bottom,top] and [card_start,card_end] will be empty. Before we 275 // update the top fields, we'll do a storestore to make sure that 276 // no thread sees the update to top before the zeroing of the 277 // object header and the BOT initialization. 278 OrderAccess::storestore(); 279 280 // Now, we will update the top fields of the "continues humongous" 281 // regions except the last one. 282 for (uint i = first; i < last; ++i) { 283 hr = region_at(i); 284 hr->set_top(hr->end()); 285 } 286 287 hr = region_at(last); 288 // If we cannot fit a filler object, we must set top to the end 289 // of the humongous object, otherwise we cannot iterate the heap 290 // and the BOT will not be complete. 291 hr->set_top(hr->end() - words_not_fillable); 292 293 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 294 "obj_top should be in last region"); 295 296 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 297 298 assert(words_not_fillable == 0 || 299 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 300 "Miscalculation in humongous allocation"); 301 302 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 303 304 for (uint i = first; i <= last; ++i) { 305 hr = region_at(i); 306 _humongous_set.add(hr); 307 _hr_printer.alloc(hr); 308 } 309 310 return new_obj; 311 } 312 313 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 314 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 315 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 316 } 317 318 // If could fit into free regions w/o expansion, try. 319 // Otherwise, if can expand, do so. 320 // Otherwise, if using ex regions might help, try with ex given back. 321 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 322 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 323 324 _verifier->verify_region_sets_optional(); 325 326 uint first = G1_NO_HRM_INDEX; 327 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 328 329 if (obj_regions == 1) { 330 // Only one region to allocate, try to use a fast path by directly allocating 331 // from the free lists. Do not try to expand here, we will potentially do that 332 // later. 333 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 334 if (hr != NULL) { 335 first = hr->hrm_index(); 336 } 337 } else { 338 // Policy: Try only empty regions (i.e. already committed first). Maybe we 339 // are lucky enough to find some. 340 first = _hrm->find_contiguous_only_empty(obj_regions); 341 if (first != G1_NO_HRM_INDEX) { 342 _hrm->allocate_free_regions_starting_at(first, obj_regions); 343 } 344 } 345 346 if (first == G1_NO_HRM_INDEX) { 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, try expansion. 350 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 351 if (first != G1_NO_HRM_INDEX) { 352 // We found something. Make sure these regions are committed, i.e. expand 353 // the heap. Alternatively we could do a defragmentation GC. 354 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 355 word_size * HeapWordSize); 356 357 _hrm->expand_at(first, obj_regions, workers()); 358 g1_policy()->record_new_heap_size(num_regions()); 359 360 #ifdef ASSERT 361 for (uint i = first; i < first + obj_regions; ++i) { 362 HeapRegion* hr = region_at(i); 363 assert(hr->is_free(), "sanity"); 364 assert(hr->is_empty(), "sanity"); 365 assert(is_on_master_free_list(hr), "sanity"); 366 } 367 #endif 368 _hrm->allocate_free_regions_starting_at(first, obj_regions); 369 } else { 370 // Policy: Potentially trigger a defragmentation GC. 371 } 372 } 373 374 HeapWord* result = NULL; 375 if (first != G1_NO_HRM_INDEX) { 376 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 377 assert(result != NULL, "it should always return a valid result"); 378 379 // A successful humongous object allocation changes the used space 380 // information of the old generation so we need to recalculate the 381 // sizes and update the jstat counters here. 382 g1mm()->update_sizes(); 383 } 384 385 _verifier->verify_region_sets_optional(); 386 387 return result; 388 } 389 390 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 391 size_t requested_size, 392 size_t* actual_size) { 393 assert_heap_not_locked_and_not_at_safepoint(); 394 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 395 396 return attempt_allocation(min_size, requested_size, actual_size); 397 } 398 399 HeapWord* 400 G1CollectedHeap::mem_allocate(size_t word_size, 401 bool* gc_overhead_limit_was_exceeded) { 402 assert_heap_not_locked_and_not_at_safepoint(); 403 404 if (is_humongous(word_size)) { 405 return attempt_allocation_humongous(word_size); 406 } 407 size_t dummy = 0; 408 return attempt_allocation(word_size, word_size, &dummy); 409 } 410 411 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 412 ResourceMark rm; // For retrieving the thread names in log messages. 413 414 // Make sure you read the note in attempt_allocation_humongous(). 415 416 assert_heap_not_locked_and_not_at_safepoint(); 417 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 418 "be called for humongous allocation requests"); 419 420 // We should only get here after the first-level allocation attempt 421 // (attempt_allocation()) failed to allocate. 422 423 // We will loop until a) we manage to successfully perform the 424 // allocation or b) we successfully schedule a collection which 425 // fails to perform the allocation. b) is the only case when we'll 426 // return NULL. 427 HeapWord* result = NULL; 428 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 429 bool should_try_gc; 430 uint gc_count_before; 431 432 { 433 MutexLockerEx x(Heap_lock); 434 result = _allocator->attempt_allocation_locked(word_size); 435 if (result != NULL) { 436 return result; 437 } 438 439 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 440 // This is different to when only GCLocker::needs_gc() is set: try to avoid 441 // waiting because the GCLocker is active to not wait too long. 442 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 443 // No need for an ergo message here, can_expand_young_list() does this when 444 // it returns true. 445 result = _allocator->attempt_allocation_force(word_size); 446 if (result != NULL) { 447 return result; 448 } 449 } 450 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 451 // the GCLocker initiated GC has been performed and then retry. This includes 452 // the case when the GC Locker is not active but has not been performed. 453 should_try_gc = !GCLocker::needs_gc(); 454 // Read the GC count while still holding the Heap_lock. 455 gc_count_before = total_collections(); 456 } 457 458 if (should_try_gc) { 459 bool succeeded; 460 result = do_collection_pause(word_size, gc_count_before, &succeeded, 461 GCCause::_g1_inc_collection_pause); 462 if (result != NULL) { 463 assert(succeeded, "only way to get back a non-NULL result"); 464 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 465 Thread::current()->name(), p2i(result)); 466 return result; 467 } 468 469 if (succeeded) { 470 // We successfully scheduled a collection which failed to allocate. No 471 // point in trying to allocate further. We'll just return NULL. 472 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 473 SIZE_FORMAT " words", Thread::current()->name(), word_size); 474 return NULL; 475 } 476 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 477 Thread::current()->name(), word_size); 478 } else { 479 // Failed to schedule a collection. 480 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 481 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 482 SIZE_FORMAT " words", Thread::current()->name(), word_size); 483 return NULL; 484 } 485 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 486 // The GCLocker is either active or the GCLocker initiated 487 // GC has not yet been performed. Stall until it is and 488 // then retry the allocation. 489 GCLocker::stall_until_clear(); 490 gclocker_retry_count += 1; 491 } 492 493 // We can reach here if we were unsuccessful in scheduling a 494 // collection (because another thread beat us to it) or if we were 495 // stalled due to the GC locker. In either can we should retry the 496 // allocation attempt in case another thread successfully 497 // performed a collection and reclaimed enough space. We do the 498 // first attempt (without holding the Heap_lock) here and the 499 // follow-on attempt will be at the start of the next loop 500 // iteration (after taking the Heap_lock). 501 size_t dummy = 0; 502 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 503 if (result != NULL) { 504 return result; 505 } 506 507 // Give a warning if we seem to be looping forever. 508 if ((QueuedAllocationWarningCount > 0) && 509 (try_count % QueuedAllocationWarningCount == 0)) { 510 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 511 Thread::current()->name(), try_count, word_size); 512 } 513 } 514 515 ShouldNotReachHere(); 516 return NULL; 517 } 518 519 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 520 assert_at_safepoint_on_vm_thread(); 521 if (_archive_allocator == NULL) { 522 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 523 } 524 } 525 526 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 527 // Allocations in archive regions cannot be of a size that would be considered 528 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 529 // may be different at archive-restore time. 530 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 531 } 532 533 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 534 assert_at_safepoint_on_vm_thread(); 535 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 536 if (is_archive_alloc_too_large(word_size)) { 537 return NULL; 538 } 539 return _archive_allocator->archive_mem_allocate(word_size); 540 } 541 542 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 543 size_t end_alignment_in_bytes) { 544 assert_at_safepoint_on_vm_thread(); 545 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 546 547 // Call complete_archive to do the real work, filling in the MemRegion 548 // array with the archive regions. 549 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 550 delete _archive_allocator; 551 _archive_allocator = NULL; 552 } 553 554 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 555 assert(ranges != NULL, "MemRegion array NULL"); 556 assert(count != 0, "No MemRegions provided"); 557 MemRegion reserved = _hrm->reserved(); 558 for (size_t i = 0; i < count; i++) { 559 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 560 return false; 561 } 562 } 563 return true; 564 } 565 566 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 567 size_t count, 568 bool open) { 569 assert(!is_init_completed(), "Expect to be called at JVM init time"); 570 assert(ranges != NULL, "MemRegion array NULL"); 571 assert(count != 0, "No MemRegions provided"); 572 MutexLockerEx x(Heap_lock); 573 574 MemRegion reserved = _hrm->reserved(); 575 HeapWord* prev_last_addr = NULL; 576 HeapRegion* prev_last_region = NULL; 577 578 // Temporarily disable pretouching of heap pages. This interface is used 579 // when mmap'ing archived heap data in, so pre-touching is wasted. 580 FlagSetting fs(AlwaysPreTouch, false); 581 582 // Enable archive object checking used by G1MarkSweep. We have to let it know 583 // about each archive range, so that objects in those ranges aren't marked. 584 G1ArchiveAllocator::enable_archive_object_check(); 585 586 // For each specified MemRegion range, allocate the corresponding G1 587 // regions and mark them as archive regions. We expect the ranges 588 // in ascending starting address order, without overlap. 589 for (size_t i = 0; i < count; i++) { 590 MemRegion curr_range = ranges[i]; 591 HeapWord* start_address = curr_range.start(); 592 size_t word_size = curr_range.word_size(); 593 HeapWord* last_address = curr_range.last(); 594 size_t commits = 0; 595 596 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 597 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 598 p2i(start_address), p2i(last_address)); 599 guarantee(start_address > prev_last_addr, 600 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 601 p2i(start_address), p2i(prev_last_addr)); 602 prev_last_addr = last_address; 603 604 // Check for ranges that start in the same G1 region in which the previous 605 // range ended, and adjust the start address so we don't try to allocate 606 // the same region again. If the current range is entirely within that 607 // region, skip it, just adjusting the recorded top. 608 HeapRegion* start_region = _hrm->addr_to_region(start_address); 609 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 610 start_address = start_region->end(); 611 if (start_address > last_address) { 612 increase_used(word_size * HeapWordSize); 613 start_region->set_top(last_address + 1); 614 continue; 615 } 616 start_region->set_top(start_address); 617 curr_range = MemRegion(start_address, last_address + 1); 618 start_region = _hrm->addr_to_region(start_address); 619 } 620 621 // Perform the actual region allocation, exiting if it fails. 622 // Then note how much new space we have allocated. 623 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 624 return false; 625 } 626 increase_used(word_size * HeapWordSize); 627 if (commits != 0) { 628 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 629 HeapRegion::GrainWords * HeapWordSize * commits); 630 631 } 632 633 // Mark each G1 region touched by the range as archive, add it to 634 // the old set, and set top. 635 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 636 HeapRegion* last_region = _hrm->addr_to_region(last_address); 637 prev_last_region = last_region; 638 639 while (curr_region != NULL) { 640 assert(curr_region->is_empty() && !curr_region->is_pinned(), 641 "Region already in use (index %u)", curr_region->hrm_index()); 642 if (open) { 643 curr_region->set_open_archive(); 644 } else { 645 curr_region->set_closed_archive(); 646 } 647 _hr_printer.alloc(curr_region); 648 _archive_set.add(curr_region); 649 HeapWord* top; 650 HeapRegion* next_region; 651 if (curr_region != last_region) { 652 top = curr_region->end(); 653 next_region = _hrm->next_region_in_heap(curr_region); 654 } else { 655 top = last_address + 1; 656 next_region = NULL; 657 } 658 curr_region->set_top(top); 659 curr_region->set_first_dead(top); 660 curr_region->set_end_of_live(top); 661 curr_region = next_region; 662 } 663 664 // Notify mark-sweep of the archive 665 G1ArchiveAllocator::set_range_archive(curr_range, open); 666 } 667 return true; 668 } 669 670 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 671 assert(!is_init_completed(), "Expect to be called at JVM init time"); 672 assert(ranges != NULL, "MemRegion array NULL"); 673 assert(count != 0, "No MemRegions provided"); 674 MemRegion reserved = _hrm->reserved(); 675 HeapWord *prev_last_addr = NULL; 676 HeapRegion* prev_last_region = NULL; 677 678 // For each MemRegion, create filler objects, if needed, in the G1 regions 679 // that contain the address range. The address range actually within the 680 // MemRegion will not be modified. That is assumed to have been initialized 681 // elsewhere, probably via an mmap of archived heap data. 682 MutexLockerEx x(Heap_lock); 683 for (size_t i = 0; i < count; i++) { 684 HeapWord* start_address = ranges[i].start(); 685 HeapWord* last_address = ranges[i].last(); 686 687 assert(reserved.contains(start_address) && reserved.contains(last_address), 688 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 689 p2i(start_address), p2i(last_address)); 690 assert(start_address > prev_last_addr, 691 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 692 p2i(start_address), p2i(prev_last_addr)); 693 694 HeapRegion* start_region = _hrm->addr_to_region(start_address); 695 HeapRegion* last_region = _hrm->addr_to_region(last_address); 696 HeapWord* bottom_address = start_region->bottom(); 697 698 // Check for a range beginning in the same region in which the 699 // previous one ended. 700 if (start_region == prev_last_region) { 701 bottom_address = prev_last_addr + 1; 702 } 703 704 // Verify that the regions were all marked as archive regions by 705 // alloc_archive_regions. 706 HeapRegion* curr_region = start_region; 707 while (curr_region != NULL) { 708 guarantee(curr_region->is_archive(), 709 "Expected archive region at index %u", curr_region->hrm_index()); 710 if (curr_region != last_region) { 711 curr_region = _hrm->next_region_in_heap(curr_region); 712 } else { 713 curr_region = NULL; 714 } 715 } 716 717 prev_last_addr = last_address; 718 prev_last_region = last_region; 719 720 // Fill the memory below the allocated range with dummy object(s), 721 // if the region bottom does not match the range start, or if the previous 722 // range ended within the same G1 region, and there is a gap. 723 if (start_address != bottom_address) { 724 size_t fill_size = pointer_delta(start_address, bottom_address); 725 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 726 increase_used(fill_size * HeapWordSize); 727 } 728 } 729 } 730 731 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 732 size_t desired_word_size, 733 size_t* actual_word_size) { 734 assert_heap_not_locked_and_not_at_safepoint(); 735 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 736 "be called for humongous allocation requests"); 737 738 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 739 740 if (result == NULL) { 741 *actual_word_size = desired_word_size; 742 result = attempt_allocation_slow(desired_word_size); 743 } 744 745 assert_heap_not_locked(); 746 if (result != NULL) { 747 assert(*actual_word_size != 0, "Actual size must have been set here"); 748 dirty_young_block(result, *actual_word_size); 749 } else { 750 *actual_word_size = 0; 751 } 752 753 return result; 754 } 755 756 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 757 assert(!is_init_completed(), "Expect to be called at JVM init time"); 758 assert(ranges != NULL, "MemRegion array NULL"); 759 assert(count != 0, "No MemRegions provided"); 760 MemRegion reserved = _hrm->reserved(); 761 HeapWord* prev_last_addr = NULL; 762 HeapRegion* prev_last_region = NULL; 763 size_t size_used = 0; 764 size_t uncommitted_regions = 0; 765 766 // For each Memregion, free the G1 regions that constitute it, and 767 // notify mark-sweep that the range is no longer to be considered 'archive.' 768 MutexLockerEx x(Heap_lock); 769 for (size_t i = 0; i < count; i++) { 770 HeapWord* start_address = ranges[i].start(); 771 HeapWord* last_address = ranges[i].last(); 772 773 assert(reserved.contains(start_address) && reserved.contains(last_address), 774 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 775 p2i(start_address), p2i(last_address)); 776 assert(start_address > prev_last_addr, 777 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 778 p2i(start_address), p2i(prev_last_addr)); 779 size_used += ranges[i].byte_size(); 780 prev_last_addr = last_address; 781 782 HeapRegion* start_region = _hrm->addr_to_region(start_address); 783 HeapRegion* last_region = _hrm->addr_to_region(last_address); 784 785 // Check for ranges that start in the same G1 region in which the previous 786 // range ended, and adjust the start address so we don't try to free 787 // the same region again. If the current range is entirely within that 788 // region, skip it. 789 if (start_region == prev_last_region) { 790 start_address = start_region->end(); 791 if (start_address > last_address) { 792 continue; 793 } 794 start_region = _hrm->addr_to_region(start_address); 795 } 796 prev_last_region = last_region; 797 798 // After verifying that each region was marked as an archive region by 799 // alloc_archive_regions, set it free and empty and uncommit it. 800 HeapRegion* curr_region = start_region; 801 while (curr_region != NULL) { 802 guarantee(curr_region->is_archive(), 803 "Expected archive region at index %u", curr_region->hrm_index()); 804 uint curr_index = curr_region->hrm_index(); 805 _archive_set.remove(curr_region); 806 curr_region->set_free(); 807 curr_region->set_top(curr_region->bottom()); 808 if (curr_region != last_region) { 809 curr_region = _hrm->next_region_in_heap(curr_region); 810 } else { 811 curr_region = NULL; 812 } 813 _hrm->shrink_at(curr_index, 1); 814 uncommitted_regions++; 815 } 816 817 // Notify mark-sweep that this is no longer an archive range. 818 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 819 } 820 821 if (uncommitted_regions != 0) { 822 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 823 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 824 } 825 decrease_used(size_used); 826 } 827 828 oop G1CollectedHeap::materialize_archived_object(oop obj) { 829 assert(obj != NULL, "archived obj is NULL"); 830 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 831 832 // Loading an archived object makes it strongly reachable. If it is 833 // loaded during concurrent marking, it must be enqueued to the SATB 834 // queue, shading the previously white object gray. 835 G1BarrierSet::enqueue(obj); 836 837 return obj; 838 } 839 840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 841 ResourceMark rm; // For retrieving the thread names in log messages. 842 843 // The structure of this method has a lot of similarities to 844 // attempt_allocation_slow(). The reason these two were not merged 845 // into a single one is that such a method would require several "if 846 // allocation is not humongous do this, otherwise do that" 847 // conditional paths which would obscure its flow. In fact, an early 848 // version of this code did use a unified method which was harder to 849 // follow and, as a result, it had subtle bugs that were hard to 850 // track down. So keeping these two methods separate allows each to 851 // be more readable. It will be good to keep these two in sync as 852 // much as possible. 853 854 assert_heap_not_locked_and_not_at_safepoint(); 855 assert(is_humongous(word_size), "attempt_allocation_humongous() " 856 "should only be called for humongous allocations"); 857 858 // Humongous objects can exhaust the heap quickly, so we should check if we 859 // need to start a marking cycle at each humongous object allocation. We do 860 // the check before we do the actual allocation. The reason for doing it 861 // before the allocation is that we avoid having to keep track of the newly 862 // allocated memory while we do a GC. 863 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 864 word_size)) { 865 collect(GCCause::_g1_humongous_allocation); 866 } 867 868 // We will loop until a) we manage to successfully perform the 869 // allocation or b) we successfully schedule a collection which 870 // fails to perform the allocation. b) is the only case when we'll 871 // return NULL. 872 HeapWord* result = NULL; 873 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 874 bool should_try_gc; 875 uint gc_count_before; 876 877 878 { 879 MutexLockerEx x(Heap_lock); 880 881 // Given that humongous objects are not allocated in young 882 // regions, we'll first try to do the allocation without doing a 883 // collection hoping that there's enough space in the heap. 884 result = humongous_obj_allocate(word_size); 885 if (result != NULL) { 886 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 887 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 888 return result; 889 } 890 891 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 892 // the GCLocker initiated GC has been performed and then retry. This includes 893 // the case when the GC Locker is not active but has not been performed. 894 should_try_gc = !GCLocker::needs_gc(); 895 // Read the GC count while still holding the Heap_lock. 896 gc_count_before = total_collections(); 897 } 898 899 if (should_try_gc) { 900 bool succeeded; 901 result = do_collection_pause(word_size, gc_count_before, &succeeded, 902 GCCause::_g1_humongous_allocation); 903 if (result != NULL) { 904 assert(succeeded, "only way to get back a non-NULL result"); 905 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 906 Thread::current()->name(), p2i(result)); 907 return result; 908 } 909 910 if (succeeded) { 911 // We successfully scheduled a collection which failed to allocate. No 912 // point in trying to allocate further. We'll just return NULL. 913 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 914 SIZE_FORMAT " words", Thread::current()->name(), word_size); 915 return NULL; 916 } 917 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 918 Thread::current()->name(), word_size); 919 } else { 920 // Failed to schedule a collection. 921 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 922 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 923 SIZE_FORMAT " words", Thread::current()->name(), word_size); 924 return NULL; 925 } 926 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 927 // The GCLocker is either active or the GCLocker initiated 928 // GC has not yet been performed. Stall until it is and 929 // then retry the allocation. 930 GCLocker::stall_until_clear(); 931 gclocker_retry_count += 1; 932 } 933 934 935 // We can reach here if we were unsuccessful in scheduling a 936 // collection (because another thread beat us to it) or if we were 937 // stalled due to the GC locker. In either can we should retry the 938 // allocation attempt in case another thread successfully 939 // performed a collection and reclaimed enough space. 940 // Humongous object allocation always needs a lock, so we wait for the retry 941 // in the next iteration of the loop, unlike for the regular iteration case. 942 // Give a warning if we seem to be looping forever. 943 944 if ((QueuedAllocationWarningCount > 0) && 945 (try_count % QueuedAllocationWarningCount == 0)) { 946 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 947 Thread::current()->name(), try_count, word_size); 948 } 949 } 950 951 ShouldNotReachHere(); 952 return NULL; 953 } 954 955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 956 bool expect_null_mutator_alloc_region) { 957 assert_at_safepoint_on_vm_thread(); 958 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 959 "the current alloc region was unexpectedly found to be non-NULL"); 960 961 if (!is_humongous(word_size)) { 962 return _allocator->attempt_allocation_locked(word_size); 963 } else { 964 HeapWord* result = humongous_obj_allocate(word_size); 965 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 966 collector_state()->set_initiate_conc_mark_if_possible(true); 967 } 968 return result; 969 } 970 971 ShouldNotReachHere(); 972 } 973 974 class PostCompactionPrinterClosure: public HeapRegionClosure { 975 private: 976 G1HRPrinter* _hr_printer; 977 public: 978 bool do_heap_region(HeapRegion* hr) { 979 assert(!hr->is_young(), "not expecting to find young regions"); 980 _hr_printer->post_compaction(hr); 981 return false; 982 } 983 984 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 985 : _hr_printer(hr_printer) { } 986 }; 987 988 void G1CollectedHeap::print_hrm_post_compaction() { 989 if (_hr_printer.is_active()) { 990 PostCompactionPrinterClosure cl(hr_printer()); 991 heap_region_iterate(&cl); 992 } 993 } 994 995 void G1CollectedHeap::abort_concurrent_cycle() { 996 // If we start the compaction before the CM threads finish 997 // scanning the root regions we might trip them over as we'll 998 // be moving objects / updating references. So let's wait until 999 // they are done. By telling them to abort, they should complete 1000 // early. 1001 _cm->root_regions()->abort(); 1002 _cm->root_regions()->wait_until_scan_finished(); 1003 1004 // Disable discovery and empty the discovered lists 1005 // for the CM ref processor. 1006 _ref_processor_cm->disable_discovery(); 1007 _ref_processor_cm->abandon_partial_discovery(); 1008 _ref_processor_cm->verify_no_references_recorded(); 1009 1010 // Abandon current iterations of concurrent marking and concurrent 1011 // refinement, if any are in progress. 1012 concurrent_mark()->concurrent_cycle_abort(); 1013 } 1014 1015 void G1CollectedHeap::prepare_heap_for_full_collection() { 1016 // Make sure we'll choose a new allocation region afterwards. 1017 _allocator->release_mutator_alloc_region(); 1018 _allocator->abandon_gc_alloc_regions(); 1019 1020 // We may have added regions to the current incremental collection 1021 // set between the last GC or pause and now. We need to clear the 1022 // incremental collection set and then start rebuilding it afresh 1023 // after this full GC. 1024 abandon_collection_set(collection_set()); 1025 1026 tear_down_region_sets(false /* free_list_only */); 1027 1028 hrm()->prepare_for_full_collection_start(); 1029 } 1030 1031 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1032 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1033 assert(used() == recalculate_used(), "Should be equal"); 1034 _verifier->verify_region_sets_optional(); 1035 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1036 _verifier->check_bitmaps("Full GC Start"); 1037 } 1038 1039 void G1CollectedHeap::prepare_heap_for_mutators() { 1040 hrm()->prepare_for_full_collection_end(); 1041 1042 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1043 ClassLoaderDataGraph::purge(); 1044 MetaspaceUtils::verify_metrics(); 1045 1046 // Prepare heap for normal collections. 1047 assert(num_free_regions() == 0, "we should not have added any free regions"); 1048 rebuild_region_sets(false /* free_list_only */); 1049 abort_refinement(); 1050 resize_heap_if_necessary(); 1051 1052 // Rebuild the strong code root lists for each region 1053 rebuild_strong_code_roots(); 1054 1055 // Purge code root memory 1056 purge_code_root_memory(); 1057 1058 // Start a new incremental collection set for the next pause 1059 start_new_collection_set(); 1060 1061 _allocator->init_mutator_alloc_region(); 1062 1063 // Post collection state updates. 1064 MetaspaceGC::compute_new_size(); 1065 } 1066 1067 void G1CollectedHeap::abort_refinement() { 1068 if (_hot_card_cache->use_cache()) { 1069 _hot_card_cache->reset_hot_cache(); 1070 } 1071 1072 // Discard all remembered set updates. 1073 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1074 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1075 } 1076 1077 void G1CollectedHeap::verify_after_full_collection() { 1078 _hrm->verify_optional(); 1079 _verifier->verify_region_sets_optional(); 1080 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1081 // Clear the previous marking bitmap, if needed for bitmap verification. 1082 // Note we cannot do this when we clear the next marking bitmap in 1083 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1084 // objects marked during a full GC against the previous bitmap. 1085 // But we need to clear it before calling check_bitmaps below since 1086 // the full GC has compacted objects and updated TAMS but not updated 1087 // the prev bitmap. 1088 if (G1VerifyBitmaps) { 1089 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification"); 1090 _cm->clear_prev_bitmap(workers()); 1091 } 1092 // This call implicitly verifies that the next bitmap is clear after Full GC. 1093 _verifier->check_bitmaps("Full GC End"); 1094 1095 // At this point there should be no regions in the 1096 // entire heap tagged as young. 1097 assert(check_young_list_empty(), "young list should be empty at this point"); 1098 1099 // Note: since we've just done a full GC, concurrent 1100 // marking is no longer active. Therefore we need not 1101 // re-enable reference discovery for the CM ref processor. 1102 // That will be done at the start of the next marking cycle. 1103 // We also know that the STW processor should no longer 1104 // discover any new references. 1105 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1106 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1107 _ref_processor_stw->verify_no_references_recorded(); 1108 _ref_processor_cm->verify_no_references_recorded(); 1109 } 1110 1111 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1112 // Post collection logging. 1113 // We should do this after we potentially resize the heap so 1114 // that all the COMMIT / UNCOMMIT events are generated before 1115 // the compaction events. 1116 print_hrm_post_compaction(); 1117 heap_transition->print(); 1118 print_heap_after_gc(); 1119 print_heap_regions(); 1120 #ifdef TRACESPINNING 1121 ParallelTaskTerminator::print_termination_counts(); 1122 #endif 1123 } 1124 1125 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1126 bool clear_all_soft_refs) { 1127 assert_at_safepoint_on_vm_thread(); 1128 1129 if (GCLocker::check_active_before_gc()) { 1130 // Full GC was not completed. 1131 return false; 1132 } 1133 1134 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1135 soft_ref_policy()->should_clear_all_soft_refs(); 1136 1137 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1138 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1139 1140 collector.prepare_collection(); 1141 collector.collect(); 1142 collector.complete_collection(); 1143 1144 // Full collection was successfully completed. 1145 return true; 1146 } 1147 1148 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1149 // Currently, there is no facility in the do_full_collection(bool) API to notify 1150 // the caller that the collection did not succeed (e.g., because it was locked 1151 // out by the GC locker). So, right now, we'll ignore the return value. 1152 bool dummy = do_full_collection(true, /* explicit_gc */ 1153 clear_all_soft_refs); 1154 } 1155 1156 void G1CollectedHeap::resize_heap_if_necessary() { 1157 assert_at_safepoint_on_vm_thread(); 1158 1159 // Capacity, free and used after the GC counted as full regions to 1160 // include the waste in the following calculations. 1161 const size_t capacity_after_gc = capacity(); 1162 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1163 1164 // This is enforced in arguments.cpp. 1165 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1166 "otherwise the code below doesn't make sense"); 1167 1168 // We don't have floating point command-line arguments 1169 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1170 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1171 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1172 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1173 1174 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1175 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1176 1177 // We have to be careful here as these two calculations can overflow 1178 // 32-bit size_t's. 1179 double used_after_gc_d = (double) used_after_gc; 1180 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1181 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1182 1183 // Let's make sure that they are both under the max heap size, which 1184 // by default will make them fit into a size_t. 1185 double desired_capacity_upper_bound = (double) max_heap_size; 1186 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1187 desired_capacity_upper_bound); 1188 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1189 desired_capacity_upper_bound); 1190 1191 // We can now safely turn them into size_t's. 1192 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1193 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1194 1195 // This assert only makes sense here, before we adjust them 1196 // with respect to the min and max heap size. 1197 assert(minimum_desired_capacity <= maximum_desired_capacity, 1198 "minimum_desired_capacity = " SIZE_FORMAT ", " 1199 "maximum_desired_capacity = " SIZE_FORMAT, 1200 minimum_desired_capacity, maximum_desired_capacity); 1201 1202 // Should not be greater than the heap max size. No need to adjust 1203 // it with respect to the heap min size as it's a lower bound (i.e., 1204 // we'll try to make the capacity larger than it, not smaller). 1205 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1206 // Should not be less than the heap min size. No need to adjust it 1207 // with respect to the heap max size as it's an upper bound (i.e., 1208 // we'll try to make the capacity smaller than it, not greater). 1209 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1210 1211 if (capacity_after_gc < minimum_desired_capacity) { 1212 // Don't expand unless it's significant 1213 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1214 1215 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1216 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1217 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1218 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1219 1220 expand(expand_bytes, _workers); 1221 1222 // No expansion, now see if we want to shrink 1223 } else if (capacity_after_gc > maximum_desired_capacity) { 1224 // Capacity too large, compute shrinking size 1225 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1226 1227 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1228 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1229 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1230 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1231 1232 shrink(shrink_bytes); 1233 } 1234 } 1235 1236 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1237 bool do_gc, 1238 bool clear_all_soft_refs, 1239 bool expect_null_mutator_alloc_region, 1240 bool* gc_succeeded) { 1241 *gc_succeeded = true; 1242 // Let's attempt the allocation first. 1243 HeapWord* result = 1244 attempt_allocation_at_safepoint(word_size, 1245 expect_null_mutator_alloc_region); 1246 if (result != NULL) { 1247 return result; 1248 } 1249 1250 // In a G1 heap, we're supposed to keep allocation from failing by 1251 // incremental pauses. Therefore, at least for now, we'll favor 1252 // expansion over collection. (This might change in the future if we can 1253 // do something smarter than full collection to satisfy a failed alloc.) 1254 result = expand_and_allocate(word_size); 1255 if (result != NULL) { 1256 return result; 1257 } 1258 1259 if (do_gc) { 1260 // Expansion didn't work, we'll try to do a Full GC. 1261 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1262 clear_all_soft_refs); 1263 } 1264 1265 return NULL; 1266 } 1267 1268 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1269 bool* succeeded) { 1270 assert_at_safepoint_on_vm_thread(); 1271 1272 // Attempts to allocate followed by Full GC. 1273 HeapWord* result = 1274 satisfy_failed_allocation_helper(word_size, 1275 true, /* do_gc */ 1276 false, /* clear_all_soft_refs */ 1277 false, /* expect_null_mutator_alloc_region */ 1278 succeeded); 1279 1280 if (result != NULL || !*succeeded) { 1281 return result; 1282 } 1283 1284 // Attempts to allocate followed by Full GC that will collect all soft references. 1285 result = satisfy_failed_allocation_helper(word_size, 1286 true, /* do_gc */ 1287 true, /* clear_all_soft_refs */ 1288 true, /* expect_null_mutator_alloc_region */ 1289 succeeded); 1290 1291 if (result != NULL || !*succeeded) { 1292 return result; 1293 } 1294 1295 // Attempts to allocate, no GC 1296 result = satisfy_failed_allocation_helper(word_size, 1297 false, /* do_gc */ 1298 false, /* clear_all_soft_refs */ 1299 true, /* expect_null_mutator_alloc_region */ 1300 succeeded); 1301 1302 if (result != NULL) { 1303 return result; 1304 } 1305 1306 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1307 "Flag should have been handled and cleared prior to this point"); 1308 1309 // What else? We might try synchronous finalization later. If the total 1310 // space available is large enough for the allocation, then a more 1311 // complete compaction phase than we've tried so far might be 1312 // appropriate. 1313 return NULL; 1314 } 1315 1316 // Attempting to expand the heap sufficiently 1317 // to support an allocation of the given "word_size". If 1318 // successful, perform the allocation and return the address of the 1319 // allocated block, or else "NULL". 1320 1321 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1322 assert_at_safepoint_on_vm_thread(); 1323 1324 _verifier->verify_region_sets_optional(); 1325 1326 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1327 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1328 word_size * HeapWordSize); 1329 1330 1331 if (expand(expand_bytes, _workers)) { 1332 _hrm->verify_optional(); 1333 _verifier->verify_region_sets_optional(); 1334 return attempt_allocation_at_safepoint(word_size, 1335 false /* expect_null_mutator_alloc_region */); 1336 } 1337 return NULL; 1338 } 1339 1340 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1341 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1342 aligned_expand_bytes = align_up(aligned_expand_bytes, 1343 HeapRegion::GrainBytes); 1344 1345 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1346 expand_bytes, aligned_expand_bytes); 1347 1348 if (is_maximal_no_gc()) { 1349 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1350 return false; 1351 } 1352 1353 double expand_heap_start_time_sec = os::elapsedTime(); 1354 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1355 assert(regions_to_expand > 0, "Must expand by at least one region"); 1356 1357 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1358 if (expand_time_ms != NULL) { 1359 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1360 } 1361 1362 if (expanded_by > 0) { 1363 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1364 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1365 g1_policy()->record_new_heap_size(num_regions()); 1366 } else { 1367 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1368 1369 // The expansion of the virtual storage space was unsuccessful. 1370 // Let's see if it was because we ran out of swap. 1371 if (G1ExitOnExpansionFailure && 1372 _hrm->available() >= regions_to_expand) { 1373 // We had head room... 1374 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1375 } 1376 } 1377 return regions_to_expand > 0; 1378 } 1379 1380 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1381 size_t aligned_shrink_bytes = 1382 ReservedSpace::page_align_size_down(shrink_bytes); 1383 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1384 HeapRegion::GrainBytes); 1385 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1386 1387 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1388 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1389 1390 1391 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", 1392 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1393 if (num_regions_removed > 0) { 1394 g1_policy()->record_new_heap_size(num_regions()); 1395 } else { 1396 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1397 } 1398 } 1399 1400 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1401 _verifier->verify_region_sets_optional(); 1402 1403 // We should only reach here at the end of a Full GC or during Remark which 1404 // means we should not not be holding to any GC alloc regions. The method 1405 // below will make sure of that and do any remaining clean up. 1406 _allocator->abandon_gc_alloc_regions(); 1407 1408 // Instead of tearing down / rebuilding the free lists here, we 1409 // could instead use the remove_all_pending() method on free_list to 1410 // remove only the ones that we need to remove. 1411 tear_down_region_sets(true /* free_list_only */); 1412 shrink_helper(shrink_bytes); 1413 rebuild_region_sets(true /* free_list_only */); 1414 1415 _hrm->verify_optional(); 1416 _verifier->verify_region_sets_optional(); 1417 } 1418 1419 class OldRegionSetChecker : public HeapRegionSetChecker { 1420 public: 1421 void check_mt_safety() { 1422 // Master Old Set MT safety protocol: 1423 // (a) If we're at a safepoint, operations on the master old set 1424 // should be invoked: 1425 // - by the VM thread (which will serialize them), or 1426 // - by the GC workers while holding the FreeList_lock, if we're 1427 // at a safepoint for an evacuation pause (this lock is taken 1428 // anyway when an GC alloc region is retired so that a new one 1429 // is allocated from the free list), or 1430 // - by the GC workers while holding the OldSets_lock, if we're at a 1431 // safepoint for a cleanup pause. 1432 // (b) If we're not at a safepoint, operations on the master old set 1433 // should be invoked while holding the Heap_lock. 1434 1435 if (SafepointSynchronize::is_at_safepoint()) { 1436 guarantee(Thread::current()->is_VM_thread() || 1437 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1438 "master old set MT safety protocol at a safepoint"); 1439 } else { 1440 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1441 } 1442 } 1443 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1444 const char* get_description() { return "Old Regions"; } 1445 }; 1446 1447 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1448 public: 1449 void check_mt_safety() { 1450 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1451 "May only change archive regions during initialization or safepoint."); 1452 } 1453 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1454 const char* get_description() { return "Archive Regions"; } 1455 }; 1456 1457 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1458 public: 1459 void check_mt_safety() { 1460 // Humongous Set MT safety protocol: 1461 // (a) If we're at a safepoint, operations on the master humongous 1462 // set should be invoked by either the VM thread (which will 1463 // serialize them) or by the GC workers while holding the 1464 // OldSets_lock. 1465 // (b) If we're not at a safepoint, operations on the master 1466 // humongous set should be invoked while holding the Heap_lock. 1467 1468 if (SafepointSynchronize::is_at_safepoint()) { 1469 guarantee(Thread::current()->is_VM_thread() || 1470 OldSets_lock->owned_by_self(), 1471 "master humongous set MT safety protocol at a safepoint"); 1472 } else { 1473 guarantee(Heap_lock->owned_by_self(), 1474 "master humongous set MT safety protocol outside a safepoint"); 1475 } 1476 } 1477 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1478 const char* get_description() { return "Humongous Regions"; } 1479 }; 1480 1481 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1482 CollectedHeap(), 1483 _young_gen_sampling_thread(NULL), 1484 _workers(NULL), 1485 _collector_policy(collector_policy), 1486 _card_table(NULL), 1487 _soft_ref_policy(), 1488 _old_set("Old Region Set", new OldRegionSetChecker()), 1489 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1490 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1491 _bot(NULL), 1492 _listener(), 1493 _hrm(NULL), 1494 _allocator(NULL), 1495 _verifier(NULL), 1496 _summary_bytes_used(0), 1497 _archive_allocator(NULL), 1498 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1499 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1500 _expand_heap_after_alloc_failure(true), 1501 _g1mm(NULL), 1502 _humongous_reclaim_candidates(), 1503 _has_humongous_reclaim_candidates(false), 1504 _hr_printer(), 1505 _collector_state(), 1506 _old_marking_cycles_started(0), 1507 _old_marking_cycles_completed(0), 1508 _eden(), 1509 _survivor(), 1510 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1511 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1512 _g1_policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)), 1513 _heap_sizing_policy(NULL), 1514 _collection_set(this, _g1_policy), 1515 _hot_card_cache(NULL), 1516 _g1_rem_set(NULL), 1517 _dirty_card_queue_set(false), 1518 _cm(NULL), 1519 _cm_thread(NULL), 1520 _cr(NULL), 1521 _task_queues(NULL), 1522 _evacuation_failed(false), 1523 _evacuation_failed_info_array(NULL), 1524 _preserved_marks_set(true /* in_c_heap */), 1525 #ifndef PRODUCT 1526 _evacuation_failure_alot_for_current_gc(false), 1527 _evacuation_failure_alot_gc_number(0), 1528 _evacuation_failure_alot_count(0), 1529 #endif 1530 _ref_processor_stw(NULL), 1531 _is_alive_closure_stw(this), 1532 _is_subject_to_discovery_stw(this), 1533 _ref_processor_cm(NULL), 1534 _is_alive_closure_cm(this), 1535 _is_subject_to_discovery_cm(this), 1536 _in_cset_fast_test() { 1537 1538 _verifier = new G1HeapVerifier(this); 1539 1540 _allocator = new G1Allocator(this); 1541 1542 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1543 1544 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1545 1546 // Override the default _filler_array_max_size so that no humongous filler 1547 // objects are created. 1548 _filler_array_max_size = _humongous_object_threshold_in_words; 1549 1550 uint n_queues = ParallelGCThreads; 1551 _task_queues = new RefToScanQueueSet(n_queues); 1552 1553 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1554 1555 for (uint i = 0; i < n_queues; i++) { 1556 RefToScanQueue* q = new RefToScanQueue(); 1557 q->initialize(); 1558 _task_queues->register_queue(i, q); 1559 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1560 } 1561 1562 // Initialize the G1EvacuationFailureALot counters and flags. 1563 NOT_PRODUCT(reset_evacuation_should_fail();) 1564 1565 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1566 } 1567 1568 static size_t actual_reserved_page_size(ReservedSpace rs) { 1569 size_t page_size = os::vm_page_size(); 1570 if (UseLargePages) { 1571 // There are two ways to manage large page memory. 1572 // 1. OS supports committing large page memory. 1573 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1574 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1575 // we reserved memory without large page. 1576 if (os::can_commit_large_page_memory() || rs.special()) { 1577 page_size = rs.alignment(); 1578 } 1579 } 1580 1581 return page_size; 1582 } 1583 1584 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1585 size_t size, 1586 size_t translation_factor) { 1587 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1588 // Allocate a new reserved space, preferring to use large pages. 1589 ReservedSpace rs(size, preferred_page_size); 1590 size_t page_size = actual_reserved_page_size(rs); 1591 G1RegionToSpaceMapper* result = 1592 G1RegionToSpaceMapper::create_mapper(rs, 1593 size, 1594 page_size, 1595 HeapRegion::GrainBytes, 1596 translation_factor, 1597 mtGC); 1598 1599 os::trace_page_sizes_for_requested_size(description, 1600 size, 1601 preferred_page_size, 1602 page_size, 1603 rs.base(), 1604 rs.size()); 1605 1606 return result; 1607 } 1608 1609 jint G1CollectedHeap::initialize_concurrent_refinement() { 1610 jint ecode = JNI_OK; 1611 _cr = G1ConcurrentRefine::create(&ecode); 1612 return ecode; 1613 } 1614 1615 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1616 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1617 if (_young_gen_sampling_thread->osthread() == NULL) { 1618 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1619 return JNI_ENOMEM; 1620 } 1621 return JNI_OK; 1622 } 1623 1624 jint G1CollectedHeap::initialize() { 1625 os::enable_vtime(); 1626 1627 // Necessary to satisfy locking discipline assertions. 1628 1629 MutexLocker x(Heap_lock); 1630 1631 // While there are no constraints in the GC code that HeapWordSize 1632 // be any particular value, there are multiple other areas in the 1633 // system which believe this to be true (e.g. oop->object_size in some 1634 // cases incorrectly returns the size in wordSize units rather than 1635 // HeapWordSize). 1636 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1637 1638 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1639 size_t max_byte_size = g1_collector_policy()->heap_reserved_size_bytes(); 1640 size_t heap_alignment = collector_policy()->heap_alignment(); 1641 1642 // Ensure that the sizes are properly aligned. 1643 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1644 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1645 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1646 1647 // Reserve the maximum. 1648 1649 // When compressed oops are enabled, the preferred heap base 1650 // is calculated by subtracting the requested size from the 1651 // 32Gb boundary and using the result as the base address for 1652 // heap reservation. If the requested size is not aligned to 1653 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1654 // into the ReservedHeapSpace constructor) then the actual 1655 // base of the reserved heap may end up differing from the 1656 // address that was requested (i.e. the preferred heap base). 1657 // If this happens then we could end up using a non-optimal 1658 // compressed oops mode. 1659 1660 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1661 heap_alignment); 1662 1663 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1664 1665 // Create the barrier set for the entire reserved region. 1666 G1CardTable* ct = new G1CardTable(reserved_region()); 1667 ct->initialize(); 1668 G1BarrierSet* bs = new G1BarrierSet(ct); 1669 bs->initialize(); 1670 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1671 BarrierSet::set_barrier_set(bs); 1672 _card_table = ct; 1673 1674 G1BarrierSet::satb_mark_queue_set().initialize(this, 1675 SATB_Q_CBL_mon, 1676 &bs->satb_mark_queue_buffer_allocator(), 1677 G1SATBProcessCompletedThreshold, 1678 G1SATBBufferEnqueueingThresholdPercent, 1679 Shared_SATB_Q_lock); 1680 1681 // process_completed_buffers_threshold and max_completed_buffers are updated 1682 // later, based on the concurrent refinement object. 1683 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1684 &bs->dirty_card_queue_buffer_allocator(), 1685 Shared_DirtyCardQ_lock, 1686 true); // init_free_ids 1687 1688 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1689 &bs->dirty_card_queue_buffer_allocator(), 1690 Shared_DirtyCardQ_lock); 1691 1692 // Create the hot card cache. 1693 _hot_card_cache = new G1HotCardCache(this); 1694 1695 // Carve out the G1 part of the heap. 1696 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1697 size_t page_size = actual_reserved_page_size(heap_rs); 1698 G1RegionToSpaceMapper* heap_storage = 1699 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1700 g1_rs.size(), 1701 page_size, 1702 HeapRegion::GrainBytes, 1703 1, 1704 mtJavaHeap); 1705 if(heap_storage == NULL) { 1706 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1707 return JNI_ERR; 1708 } 1709 1710 os::trace_page_sizes("Heap", 1711 collector_policy()->min_heap_byte_size(), 1712 max_byte_size, 1713 page_size, 1714 heap_rs.base(), 1715 heap_rs.size()); 1716 heap_storage->set_mapping_changed_listener(&_listener); 1717 1718 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1719 G1RegionToSpaceMapper* bot_storage = 1720 create_aux_memory_mapper("Block Offset Table", 1721 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1722 G1BlockOffsetTable::heap_map_factor()); 1723 1724 G1RegionToSpaceMapper* cardtable_storage = 1725 create_aux_memory_mapper("Card Table", 1726 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1727 G1CardTable::heap_map_factor()); 1728 1729 G1RegionToSpaceMapper* card_counts_storage = 1730 create_aux_memory_mapper("Card Counts Table", 1731 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1732 G1CardCounts::heap_map_factor()); 1733 1734 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1735 G1RegionToSpaceMapper* prev_bitmap_storage = 1736 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1737 G1RegionToSpaceMapper* next_bitmap_storage = 1738 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1739 1740 _hrm = HeapRegionManager::create_manager(this, g1_collector_policy()); 1741 1742 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1743 _card_table->initialize(cardtable_storage); 1744 // Do later initialization work for concurrent refinement. 1745 _hot_card_cache->initialize(card_counts_storage); 1746 1747 // 6843694 - ensure that the maximum region index can fit 1748 // in the remembered set structures. 1749 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1750 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1751 1752 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1753 // start within the first card. 1754 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1755 // Also create a G1 rem set. 1756 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1757 _g1_rem_set->initialize(max_reserved_capacity(), max_regions()); 1758 1759 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1760 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1761 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1762 "too many cards per region"); 1763 1764 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1765 1766 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1767 1768 { 1769 HeapWord* start = _hrm->reserved().start(); 1770 HeapWord* end = _hrm->reserved().end(); 1771 size_t granularity = HeapRegion::GrainBytes; 1772 1773 _in_cset_fast_test.initialize(start, end, granularity); 1774 _humongous_reclaim_candidates.initialize(start, end, granularity); 1775 } 1776 1777 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1778 true /* are_GC_task_threads */, 1779 false /* are_ConcurrentGC_threads */); 1780 if (_workers == NULL) { 1781 return JNI_ENOMEM; 1782 } 1783 _workers->initialize_workers(); 1784 1785 // Create the G1ConcurrentMark data structure and thread. 1786 // (Must do this late, so that "max_regions" is defined.) 1787 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1788 if (_cm == NULL || !_cm->completed_initialization()) { 1789 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1790 return JNI_ENOMEM; 1791 } 1792 _cm_thread = _cm->cm_thread(); 1793 1794 // Now expand into the initial heap size. 1795 if (!expand(init_byte_size, _workers)) { 1796 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1797 return JNI_ENOMEM; 1798 } 1799 1800 // Perform any initialization actions delegated to the policy. 1801 g1_policy()->init(this, &_collection_set); 1802 1803 jint ecode = initialize_concurrent_refinement(); 1804 if (ecode != JNI_OK) { 1805 return ecode; 1806 } 1807 1808 ecode = initialize_young_gen_sampling_thread(); 1809 if (ecode != JNI_OK) { 1810 return ecode; 1811 } 1812 1813 { 1814 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1815 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone()); 1816 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone()); 1817 } 1818 1819 // Here we allocate the dummy HeapRegion that is required by the 1820 // G1AllocRegion class. 1821 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1822 1823 // We'll re-use the same region whether the alloc region will 1824 // require BOT updates or not and, if it doesn't, then a non-young 1825 // region will complain that it cannot support allocations without 1826 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1827 dummy_region->set_eden(); 1828 // Make sure it's full. 1829 dummy_region->set_top(dummy_region->end()); 1830 G1AllocRegion::setup(this, dummy_region); 1831 1832 _allocator->init_mutator_alloc_region(); 1833 1834 // Do create of the monitoring and management support so that 1835 // values in the heap have been properly initialized. 1836 _g1mm = new G1MonitoringSupport(this); 1837 1838 G1StringDedup::initialize(); 1839 1840 _preserved_marks_set.init(ParallelGCThreads); 1841 1842 _collection_set.initialize(max_regions()); 1843 1844 return JNI_OK; 1845 } 1846 1847 void G1CollectedHeap::stop() { 1848 // Stop all concurrent threads. We do this to make sure these threads 1849 // do not continue to execute and access resources (e.g. logging) 1850 // that are destroyed during shutdown. 1851 _cr->stop(); 1852 _young_gen_sampling_thread->stop(); 1853 _cm_thread->stop(); 1854 if (G1StringDedup::is_enabled()) { 1855 G1StringDedup::stop(); 1856 } 1857 } 1858 1859 void G1CollectedHeap::safepoint_synchronize_begin() { 1860 SuspendibleThreadSet::synchronize(); 1861 } 1862 1863 void G1CollectedHeap::safepoint_synchronize_end() { 1864 SuspendibleThreadSet::desynchronize(); 1865 } 1866 1867 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1868 return HeapRegion::max_region_size(); 1869 } 1870 1871 void G1CollectedHeap::post_initialize() { 1872 CollectedHeap::post_initialize(); 1873 ref_processing_init(); 1874 } 1875 1876 void G1CollectedHeap::ref_processing_init() { 1877 // Reference processing in G1 currently works as follows: 1878 // 1879 // * There are two reference processor instances. One is 1880 // used to record and process discovered references 1881 // during concurrent marking; the other is used to 1882 // record and process references during STW pauses 1883 // (both full and incremental). 1884 // * Both ref processors need to 'span' the entire heap as 1885 // the regions in the collection set may be dotted around. 1886 // 1887 // * For the concurrent marking ref processor: 1888 // * Reference discovery is enabled at initial marking. 1889 // * Reference discovery is disabled and the discovered 1890 // references processed etc during remarking. 1891 // * Reference discovery is MT (see below). 1892 // * Reference discovery requires a barrier (see below). 1893 // * Reference processing may or may not be MT 1894 // (depending on the value of ParallelRefProcEnabled 1895 // and ParallelGCThreads). 1896 // * A full GC disables reference discovery by the CM 1897 // ref processor and abandons any entries on it's 1898 // discovered lists. 1899 // 1900 // * For the STW processor: 1901 // * Non MT discovery is enabled at the start of a full GC. 1902 // * Processing and enqueueing during a full GC is non-MT. 1903 // * During a full GC, references are processed after marking. 1904 // 1905 // * Discovery (may or may not be MT) is enabled at the start 1906 // of an incremental evacuation pause. 1907 // * References are processed near the end of a STW evacuation pause. 1908 // * For both types of GC: 1909 // * Discovery is atomic - i.e. not concurrent. 1910 // * Reference discovery will not need a barrier. 1911 1912 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1913 1914 // Concurrent Mark ref processor 1915 _ref_processor_cm = 1916 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1917 mt_processing, // mt processing 1918 ParallelGCThreads, // degree of mt processing 1919 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1920 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1921 false, // Reference discovery is not atomic 1922 &_is_alive_closure_cm, // is alive closure 1923 true); // allow changes to number of processing threads 1924 1925 // STW ref processor 1926 _ref_processor_stw = 1927 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1928 mt_processing, // mt processing 1929 ParallelGCThreads, // degree of mt processing 1930 (ParallelGCThreads > 1), // mt discovery 1931 ParallelGCThreads, // degree of mt discovery 1932 true, // Reference discovery is atomic 1933 &_is_alive_closure_stw, // is alive closure 1934 true); // allow changes to number of processing threads 1935 } 1936 1937 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1938 return _collector_policy; 1939 } 1940 1941 G1CollectorPolicy* G1CollectedHeap::g1_collector_policy() const { 1942 return _collector_policy; 1943 } 1944 1945 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1946 return &_soft_ref_policy; 1947 } 1948 1949 size_t G1CollectedHeap::capacity() const { 1950 return _hrm->length() * HeapRegion::GrainBytes; 1951 } 1952 1953 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1954 return _hrm->total_free_bytes(); 1955 } 1956 1957 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1958 _hot_card_cache->drain(cl, worker_i); 1959 } 1960 1961 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1962 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1963 size_t n_completed_buffers = 0; 1964 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1965 n_completed_buffers++; 1966 } 1967 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!"); 1968 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1969 } 1970 1971 // Computes the sum of the storage used by the various regions. 1972 size_t G1CollectedHeap::used() const { 1973 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1974 if (_archive_allocator != NULL) { 1975 result += _archive_allocator->used(); 1976 } 1977 return result; 1978 } 1979 1980 size_t G1CollectedHeap::used_unlocked() const { 1981 return _summary_bytes_used; 1982 } 1983 1984 class SumUsedClosure: public HeapRegionClosure { 1985 size_t _used; 1986 public: 1987 SumUsedClosure() : _used(0) {} 1988 bool do_heap_region(HeapRegion* r) { 1989 _used += r->used(); 1990 return false; 1991 } 1992 size_t result() { return _used; } 1993 }; 1994 1995 size_t G1CollectedHeap::recalculate_used() const { 1996 SumUsedClosure blk; 1997 heap_region_iterate(&blk); 1998 return blk.result(); 1999 } 2000 2001 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2002 switch (cause) { 2003 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2004 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2005 case GCCause::_wb_conc_mark: return true; 2006 default : return false; 2007 } 2008 } 2009 2010 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2011 switch (cause) { 2012 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2013 case GCCause::_g1_humongous_allocation: return true; 2014 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2015 default: return is_user_requested_concurrent_full_gc(cause); 2016 } 2017 } 2018 2019 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2020 if(g1_policy()->force_upgrade_to_full()) { 2021 return true; 2022 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2023 return false; 2024 } else if (has_regions_left_for_allocation()) { 2025 return false; 2026 } else { 2027 return true; 2028 } 2029 } 2030 2031 #ifndef PRODUCT 2032 void G1CollectedHeap::allocate_dummy_regions() { 2033 // Let's fill up most of the region 2034 size_t word_size = HeapRegion::GrainWords - 1024; 2035 // And as a result the region we'll allocate will be humongous. 2036 guarantee(is_humongous(word_size), "sanity"); 2037 2038 // _filler_array_max_size is set to humongous object threshold 2039 // but temporarily change it to use CollectedHeap::fill_with_object(). 2040 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2041 2042 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2043 // Let's use the existing mechanism for the allocation 2044 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2045 if (dummy_obj != NULL) { 2046 MemRegion mr(dummy_obj, word_size); 2047 CollectedHeap::fill_with_object(mr); 2048 } else { 2049 // If we can't allocate once, we probably cannot allocate 2050 // again. Let's get out of the loop. 2051 break; 2052 } 2053 } 2054 } 2055 #endif // !PRODUCT 2056 2057 void G1CollectedHeap::increment_old_marking_cycles_started() { 2058 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2059 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2060 "Wrong marking cycle count (started: %d, completed: %d)", 2061 _old_marking_cycles_started, _old_marking_cycles_completed); 2062 2063 _old_marking_cycles_started++; 2064 } 2065 2066 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2067 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2068 2069 // We assume that if concurrent == true, then the caller is a 2070 // concurrent thread that was joined the Suspendible Thread 2071 // Set. If there's ever a cheap way to check this, we should add an 2072 // assert here. 2073 2074 // Given that this method is called at the end of a Full GC or of a 2075 // concurrent cycle, and those can be nested (i.e., a Full GC can 2076 // interrupt a concurrent cycle), the number of full collections 2077 // completed should be either one (in the case where there was no 2078 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2079 // behind the number of full collections started. 2080 2081 // This is the case for the inner caller, i.e. a Full GC. 2082 assert(concurrent || 2083 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2085 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2086 "is inconsistent with _old_marking_cycles_completed = %u", 2087 _old_marking_cycles_started, _old_marking_cycles_completed); 2088 2089 // This is the case for the outer caller, i.e. the concurrent cycle. 2090 assert(!concurrent || 2091 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2092 "for outer caller (concurrent cycle): " 2093 "_old_marking_cycles_started = %u " 2094 "is inconsistent with _old_marking_cycles_completed = %u", 2095 _old_marking_cycles_started, _old_marking_cycles_completed); 2096 2097 _old_marking_cycles_completed += 1; 2098 2099 // We need to clear the "in_progress" flag in the CM thread before 2100 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2101 // is set) so that if a waiter requests another System.gc() it doesn't 2102 // incorrectly see that a marking cycle is still in progress. 2103 if (concurrent) { 2104 _cm_thread->set_idle(); 2105 } 2106 2107 // This notify_all() will ensure that a thread that called 2108 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2109 // and it's waiting for a full GC to finish will be woken up. It is 2110 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2111 FullGCCount_lock->notify_all(); 2112 } 2113 2114 void G1CollectedHeap::collect(GCCause::Cause cause) { 2115 assert_heap_not_locked(); 2116 2117 uint gc_count_before; 2118 uint old_marking_count_before; 2119 uint full_gc_count_before; 2120 bool retry_gc; 2121 2122 do { 2123 retry_gc = false; 2124 2125 { 2126 MutexLocker ml(Heap_lock); 2127 2128 // Read the GC count while holding the Heap_lock 2129 gc_count_before = total_collections(); 2130 full_gc_count_before = total_full_collections(); 2131 old_marking_count_before = _old_marking_cycles_started; 2132 } 2133 2134 if (should_do_concurrent_full_gc(cause)) { 2135 // Schedule an initial-mark evacuation pause that will start a 2136 // concurrent cycle. We're setting word_size to 0 which means that 2137 // we are not requesting a post-GC allocation. 2138 VM_G1CollectForAllocation op(0, /* word_size */ 2139 gc_count_before, 2140 cause, 2141 true, /* should_initiate_conc_mark */ 2142 g1_policy()->max_pause_time_ms()); 2143 VMThread::execute(&op); 2144 if (!op.pause_succeeded()) { 2145 if (old_marking_count_before == _old_marking_cycles_started) { 2146 retry_gc = op.should_retry_gc(); 2147 } else { 2148 // A Full GC happened while we were trying to schedule the 2149 // initial-mark GC. No point in starting a new cycle given 2150 // that the whole heap was collected anyway. 2151 } 2152 2153 if (retry_gc) { 2154 if (GCLocker::is_active_and_needs_gc()) { 2155 GCLocker::stall_until_clear(); 2156 } 2157 } 2158 } 2159 } else { 2160 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2161 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2162 2163 // Schedule a standard evacuation pause. We're setting word_size 2164 // to 0 which means that we are not requesting a post-GC allocation. 2165 VM_G1CollectForAllocation op(0, /* word_size */ 2166 gc_count_before, 2167 cause, 2168 false, /* should_initiate_conc_mark */ 2169 g1_policy()->max_pause_time_ms()); 2170 VMThread::execute(&op); 2171 } else { 2172 // Schedule a Full GC. 2173 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2174 VMThread::execute(&op); 2175 } 2176 } 2177 } while (retry_gc); 2178 } 2179 2180 bool G1CollectedHeap::is_in(const void* p) const { 2181 if (_hrm->reserved().contains(p)) { 2182 // Given that we know that p is in the reserved space, 2183 // heap_region_containing() should successfully 2184 // return the containing region. 2185 HeapRegion* hr = heap_region_containing(p); 2186 return hr->is_in(p); 2187 } else { 2188 return false; 2189 } 2190 } 2191 2192 #ifdef ASSERT 2193 bool G1CollectedHeap::is_in_exact(const void* p) const { 2194 bool contains = reserved_region().contains(p); 2195 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2196 if (contains && available) { 2197 return true; 2198 } else { 2199 return false; 2200 } 2201 } 2202 #endif 2203 2204 // Iteration functions. 2205 2206 // Iterates an ObjectClosure over all objects within a HeapRegion. 2207 2208 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2209 ObjectClosure* _cl; 2210 public: 2211 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2212 bool do_heap_region(HeapRegion* r) { 2213 if (!r->is_continues_humongous()) { 2214 r->object_iterate(_cl); 2215 } 2216 return false; 2217 } 2218 }; 2219 2220 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2221 IterateObjectClosureRegionClosure blk(cl); 2222 heap_region_iterate(&blk); 2223 } 2224 2225 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2226 _hrm->iterate(cl); 2227 } 2228 2229 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2230 HeapRegionClaimer *hrclaimer, 2231 uint worker_id) const { 2232 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2233 } 2234 2235 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2236 HeapRegionClaimer *hrclaimer) const { 2237 _hrm->par_iterate(cl, hrclaimer, 0); 2238 } 2239 2240 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2241 _collection_set.iterate(cl); 2242 } 2243 2244 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2245 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2246 } 2247 2248 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2249 HeapRegion* hr = heap_region_containing(addr); 2250 return hr->block_start(addr); 2251 } 2252 2253 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2254 HeapRegion* hr = heap_region_containing(addr); 2255 return hr->block_size(addr); 2256 } 2257 2258 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2259 HeapRegion* hr = heap_region_containing(addr); 2260 return hr->block_is_obj(addr); 2261 } 2262 2263 bool G1CollectedHeap::supports_tlab_allocation() const { 2264 return true; 2265 } 2266 2267 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2268 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2269 } 2270 2271 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2272 return _eden.length() * HeapRegion::GrainBytes; 2273 } 2274 2275 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2276 // must be equal to the humongous object limit. 2277 size_t G1CollectedHeap::max_tlab_size() const { 2278 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2279 } 2280 2281 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2282 return _allocator->unsafe_max_tlab_alloc(); 2283 } 2284 2285 size_t G1CollectedHeap::max_capacity() const { 2286 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2287 } 2288 2289 size_t G1CollectedHeap::max_reserved_capacity() const { 2290 return _hrm->max_length() * HeapRegion::GrainBytes; 2291 } 2292 2293 jlong G1CollectedHeap::millis_since_last_gc() { 2294 // See the notes in GenCollectedHeap::millis_since_last_gc() 2295 // for more information about the implementation. 2296 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2297 _g1_policy->collection_pause_end_millis(); 2298 if (ret_val < 0) { 2299 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2300 ". returning zero instead.", ret_val); 2301 return 0; 2302 } 2303 return ret_val; 2304 } 2305 2306 void G1CollectedHeap::deduplicate_string(oop str) { 2307 assert(java_lang_String::is_instance(str), "invariant"); 2308 2309 if (G1StringDedup::is_enabled()) { 2310 G1StringDedup::deduplicate(str); 2311 } 2312 } 2313 2314 void G1CollectedHeap::prepare_for_verify() { 2315 _verifier->prepare_for_verify(); 2316 } 2317 2318 void G1CollectedHeap::verify(VerifyOption vo) { 2319 _verifier->verify(vo); 2320 } 2321 2322 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2323 return true; 2324 } 2325 2326 const char* const* G1CollectedHeap::concurrent_phases() const { 2327 return _cm_thread->concurrent_phases(); 2328 } 2329 2330 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2331 return _cm_thread->request_concurrent_phase(phase); 2332 } 2333 2334 class PrintRegionClosure: public HeapRegionClosure { 2335 outputStream* _st; 2336 public: 2337 PrintRegionClosure(outputStream* st) : _st(st) {} 2338 bool do_heap_region(HeapRegion* r) { 2339 r->print_on(_st); 2340 return false; 2341 } 2342 }; 2343 2344 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2345 const HeapRegion* hr, 2346 const VerifyOption vo) const { 2347 switch (vo) { 2348 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2349 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2350 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2351 default: ShouldNotReachHere(); 2352 } 2353 return false; // keep some compilers happy 2354 } 2355 2356 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2357 const VerifyOption vo) const { 2358 switch (vo) { 2359 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2360 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2361 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2362 default: ShouldNotReachHere(); 2363 } 2364 return false; // keep some compilers happy 2365 } 2366 2367 void G1CollectedHeap::print_heap_regions() const { 2368 LogTarget(Trace, gc, heap, region) lt; 2369 if (lt.is_enabled()) { 2370 LogStream ls(lt); 2371 print_regions_on(&ls); 2372 } 2373 } 2374 2375 void G1CollectedHeap::print_on(outputStream* st) const { 2376 st->print(" %-20s", "garbage-first heap"); 2377 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2378 capacity()/K, used_unlocked()/K); 2379 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2380 p2i(_hrm->reserved().start()), 2381 p2i(_hrm->reserved().end())); 2382 st->cr(); 2383 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2384 uint young_regions = young_regions_count(); 2385 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2386 (size_t) young_regions * HeapRegion::GrainBytes / K); 2387 uint survivor_regions = survivor_regions_count(); 2388 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2389 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2390 st->cr(); 2391 MetaspaceUtils::print_on(st); 2392 } 2393 2394 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2395 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2396 "HS=humongous(starts), HC=humongous(continues), " 2397 "CS=collection set, F=free, A=archive, " 2398 "TAMS=top-at-mark-start (previous, next)"); 2399 PrintRegionClosure blk(st); 2400 heap_region_iterate(&blk); 2401 } 2402 2403 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2404 print_on(st); 2405 2406 // Print the per-region information. 2407 print_regions_on(st); 2408 } 2409 2410 void G1CollectedHeap::print_on_error(outputStream* st) const { 2411 this->CollectedHeap::print_on_error(st); 2412 2413 if (_cm != NULL) { 2414 st->cr(); 2415 _cm->print_on_error(st); 2416 } 2417 } 2418 2419 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2420 workers()->print_worker_threads_on(st); 2421 _cm_thread->print_on(st); 2422 st->cr(); 2423 _cm->print_worker_threads_on(st); 2424 _cr->print_threads_on(st); 2425 _young_gen_sampling_thread->print_on(st); 2426 if (G1StringDedup::is_enabled()) { 2427 G1StringDedup::print_worker_threads_on(st); 2428 } 2429 } 2430 2431 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2432 workers()->threads_do(tc); 2433 tc->do_thread(_cm_thread); 2434 _cm->threads_do(tc); 2435 _cr->threads_do(tc); 2436 tc->do_thread(_young_gen_sampling_thread); 2437 if (G1StringDedup::is_enabled()) { 2438 G1StringDedup::threads_do(tc); 2439 } 2440 } 2441 2442 void G1CollectedHeap::print_tracing_info() const { 2443 g1_rem_set()->print_summary_info(); 2444 concurrent_mark()->print_summary_info(); 2445 } 2446 2447 #ifndef PRODUCT 2448 // Helpful for debugging RSet issues. 2449 2450 class PrintRSetsClosure : public HeapRegionClosure { 2451 private: 2452 const char* _msg; 2453 size_t _occupied_sum; 2454 2455 public: 2456 bool do_heap_region(HeapRegion* r) { 2457 HeapRegionRemSet* hrrs = r->rem_set(); 2458 size_t occupied = hrrs->occupied(); 2459 _occupied_sum += occupied; 2460 2461 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2462 if (occupied == 0) { 2463 tty->print_cr(" RSet is empty"); 2464 } else { 2465 hrrs->print(); 2466 } 2467 tty->print_cr("----------"); 2468 return false; 2469 } 2470 2471 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2472 tty->cr(); 2473 tty->print_cr("========================================"); 2474 tty->print_cr("%s", msg); 2475 tty->cr(); 2476 } 2477 2478 ~PrintRSetsClosure() { 2479 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2480 tty->print_cr("========================================"); 2481 tty->cr(); 2482 } 2483 }; 2484 2485 void G1CollectedHeap::print_cset_rsets() { 2486 PrintRSetsClosure cl("Printing CSet RSets"); 2487 collection_set_iterate(&cl); 2488 } 2489 2490 void G1CollectedHeap::print_all_rsets() { 2491 PrintRSetsClosure cl("Printing All RSets");; 2492 heap_region_iterate(&cl); 2493 } 2494 #endif // PRODUCT 2495 2496 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2497 2498 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2499 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2500 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2501 2502 size_t eden_capacity_bytes = 2503 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2504 2505 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2506 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2507 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2508 } 2509 2510 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2511 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2512 stats->unused(), stats->used(), stats->region_end_waste(), 2513 stats->regions_filled(), stats->direct_allocated(), 2514 stats->failure_used(), stats->failure_waste()); 2515 } 2516 2517 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2518 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2519 gc_tracer->report_gc_heap_summary(when, heap_summary); 2520 2521 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2522 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2523 } 2524 2525 G1CollectedHeap* G1CollectedHeap::heap() { 2526 CollectedHeap* heap = Universe::heap(); 2527 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2528 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2529 return (G1CollectedHeap*)heap; 2530 } 2531 2532 void G1CollectedHeap::gc_prologue(bool full) { 2533 // always_do_update_barrier = false; 2534 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2535 2536 // This summary needs to be printed before incrementing total collections. 2537 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2538 2539 // Update common counters. 2540 increment_total_collections(full /* full gc */); 2541 if (full) { 2542 increment_old_marking_cycles_started(); 2543 } 2544 2545 // Fill TLAB's and such 2546 double start = os::elapsedTime(); 2547 ensure_parsability(true); 2548 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2549 } 2550 2551 void G1CollectedHeap::gc_epilogue(bool full) { 2552 // Update common counters. 2553 if (full) { 2554 // Update the number of full collections that have been completed. 2555 increment_old_marking_cycles_completed(false /* concurrent */); 2556 } 2557 2558 // We are at the end of the GC. Total collections has already been increased. 2559 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2560 2561 // FIXME: what is this about? 2562 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2563 // is set. 2564 #if COMPILER2_OR_JVMCI 2565 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2566 #endif 2567 // always_do_update_barrier = true; 2568 2569 double start = os::elapsedTime(); 2570 resize_all_tlabs(); 2571 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2572 2573 MemoryService::track_memory_usage(); 2574 // We have just completed a GC. Update the soft reference 2575 // policy with the new heap occupancy 2576 Universe::update_heap_info_at_gc(); 2577 } 2578 2579 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2580 uint gc_count_before, 2581 bool* succeeded, 2582 GCCause::Cause gc_cause) { 2583 assert_heap_not_locked_and_not_at_safepoint(); 2584 VM_G1CollectForAllocation op(word_size, 2585 gc_count_before, 2586 gc_cause, 2587 false, /* should_initiate_conc_mark */ 2588 g1_policy()->max_pause_time_ms()); 2589 VMThread::execute(&op); 2590 2591 HeapWord* result = op.result(); 2592 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2593 assert(result == NULL || ret_succeeded, 2594 "the result should be NULL if the VM did not succeed"); 2595 *succeeded = ret_succeeded; 2596 2597 assert_heap_not_locked(); 2598 return result; 2599 } 2600 2601 void G1CollectedHeap::do_concurrent_mark() { 2602 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2603 if (!_cm_thread->in_progress()) { 2604 _cm_thread->set_started(); 2605 CGC_lock->notify(); 2606 } 2607 } 2608 2609 size_t G1CollectedHeap::pending_card_num() { 2610 size_t extra_cards = 0; 2611 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2612 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2613 extra_cards += dcq.size(); 2614 } 2615 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2616 size_t buffer_size = dcqs.buffer_size(); 2617 size_t buffer_num = dcqs.completed_buffers_num(); 2618 2619 return buffer_size * buffer_num + extra_cards; 2620 } 2621 2622 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2623 // We don't nominate objects with many remembered set entries, on 2624 // the assumption that such objects are likely still live. 2625 HeapRegionRemSet* rem_set = r->rem_set(); 2626 2627 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2628 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2629 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2630 } 2631 2632 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2633 private: 2634 size_t _total_humongous; 2635 size_t _candidate_humongous; 2636 2637 DirtyCardQueue _dcq; 2638 2639 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2640 assert(region->is_starts_humongous(), "Must start a humongous object"); 2641 2642 oop obj = oop(region->bottom()); 2643 2644 // Dead objects cannot be eager reclaim candidates. Due to class 2645 // unloading it is unsafe to query their classes so we return early. 2646 if (g1h->is_obj_dead(obj, region)) { 2647 return false; 2648 } 2649 2650 // If we do not have a complete remembered set for the region, then we can 2651 // not be sure that we have all references to it. 2652 if (!region->rem_set()->is_complete()) { 2653 return false; 2654 } 2655 // Candidate selection must satisfy the following constraints 2656 // while concurrent marking is in progress: 2657 // 2658 // * In order to maintain SATB invariants, an object must not be 2659 // reclaimed if it was allocated before the start of marking and 2660 // has not had its references scanned. Such an object must have 2661 // its references (including type metadata) scanned to ensure no 2662 // live objects are missed by the marking process. Objects 2663 // allocated after the start of concurrent marking don't need to 2664 // be scanned. 2665 // 2666 // * An object must not be reclaimed if it is on the concurrent 2667 // mark stack. Objects allocated after the start of concurrent 2668 // marking are never pushed on the mark stack. 2669 // 2670 // Nominating only objects allocated after the start of concurrent 2671 // marking is sufficient to meet both constraints. This may miss 2672 // some objects that satisfy the constraints, but the marking data 2673 // structures don't support efficiently performing the needed 2674 // additional tests or scrubbing of the mark stack. 2675 // 2676 // However, we presently only nominate is_typeArray() objects. 2677 // A humongous object containing references induces remembered 2678 // set entries on other regions. In order to reclaim such an 2679 // object, those remembered sets would need to be cleaned up. 2680 // 2681 // We also treat is_typeArray() objects specially, allowing them 2682 // to be reclaimed even if allocated before the start of 2683 // concurrent mark. For this we rely on mark stack insertion to 2684 // exclude is_typeArray() objects, preventing reclaiming an object 2685 // that is in the mark stack. We also rely on the metadata for 2686 // such objects to be built-in and so ensured to be kept live. 2687 // Frequent allocation and drop of large binary blobs is an 2688 // important use case for eager reclaim, and this special handling 2689 // may reduce needed headroom. 2690 2691 return obj->is_typeArray() && 2692 g1h->is_potential_eager_reclaim_candidate(region); 2693 } 2694 2695 public: 2696 RegisterHumongousWithInCSetFastTestClosure() 2697 : _total_humongous(0), 2698 _candidate_humongous(0), 2699 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2700 } 2701 2702 virtual bool do_heap_region(HeapRegion* r) { 2703 if (!r->is_starts_humongous()) { 2704 return false; 2705 } 2706 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2707 2708 bool is_candidate = humongous_region_is_candidate(g1h, r); 2709 uint rindex = r->hrm_index(); 2710 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2711 if (is_candidate) { 2712 _candidate_humongous++; 2713 g1h->register_humongous_region_with_cset(rindex); 2714 // Is_candidate already filters out humongous object with large remembered sets. 2715 // If we have a humongous object with a few remembered sets, we simply flush these 2716 // remembered set entries into the DCQS. That will result in automatic 2717 // re-evaluation of their remembered set entries during the following evacuation 2718 // phase. 2719 if (!r->rem_set()->is_empty()) { 2720 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2721 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2722 G1CardTable* ct = g1h->card_table(); 2723 HeapRegionRemSetIterator hrrs(r->rem_set()); 2724 size_t card_index; 2725 while (hrrs.has_next(card_index)) { 2726 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2727 // The remembered set might contain references to already freed 2728 // regions. Filter out such entries to avoid failing card table 2729 // verification. 2730 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2731 if (*card_ptr != G1CardTable::dirty_card_val()) { 2732 *card_ptr = G1CardTable::dirty_card_val(); 2733 _dcq.enqueue(card_ptr); 2734 } 2735 } 2736 } 2737 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2738 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2739 hrrs.n_yielded(), r->rem_set()->occupied()); 2740 // We should only clear the card based remembered set here as we will not 2741 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2742 // (and probably never) we do not enter this path if there are other kind of 2743 // remembered sets for this region. 2744 r->rem_set()->clear_locked(true /* only_cardset */); 2745 // Clear_locked() above sets the state to Empty. However we want to continue 2746 // collecting remembered set entries for humongous regions that were not 2747 // reclaimed. 2748 r->rem_set()->set_state_complete(); 2749 } 2750 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2751 } 2752 _total_humongous++; 2753 2754 return false; 2755 } 2756 2757 size_t total_humongous() const { return _total_humongous; } 2758 size_t candidate_humongous() const { return _candidate_humongous; } 2759 2760 void flush_rem_set_entries() { _dcq.flush(); } 2761 }; 2762 2763 void G1CollectedHeap::register_humongous_regions_with_cset() { 2764 if (!G1EagerReclaimHumongousObjects) { 2765 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2766 return; 2767 } 2768 double time = os::elapsed_counter(); 2769 2770 // Collect reclaim candidate information and register candidates with cset. 2771 RegisterHumongousWithInCSetFastTestClosure cl; 2772 heap_region_iterate(&cl); 2773 2774 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2775 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2776 cl.total_humongous(), 2777 cl.candidate_humongous()); 2778 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2779 2780 // Finally flush all remembered set entries to re-check into the global DCQS. 2781 cl.flush_rem_set_entries(); 2782 } 2783 2784 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2785 public: 2786 bool do_heap_region(HeapRegion* hr) { 2787 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2788 hr->verify_rem_set(); 2789 } 2790 return false; 2791 } 2792 }; 2793 2794 uint G1CollectedHeap::num_task_queues() const { 2795 return _task_queues->size(); 2796 } 2797 2798 #if TASKQUEUE_STATS 2799 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2800 st->print_raw_cr("GC Task Stats"); 2801 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2802 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2803 } 2804 2805 void G1CollectedHeap::print_taskqueue_stats() const { 2806 if (!log_is_enabled(Trace, gc, task, stats)) { 2807 return; 2808 } 2809 Log(gc, task, stats) log; 2810 ResourceMark rm; 2811 LogStream ls(log.trace()); 2812 outputStream* st = &ls; 2813 2814 print_taskqueue_stats_hdr(st); 2815 2816 TaskQueueStats totals; 2817 const uint n = num_task_queues(); 2818 for (uint i = 0; i < n; ++i) { 2819 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2820 totals += task_queue(i)->stats; 2821 } 2822 st->print_raw("tot "); totals.print(st); st->cr(); 2823 2824 DEBUG_ONLY(totals.verify()); 2825 } 2826 2827 void G1CollectedHeap::reset_taskqueue_stats() { 2828 const uint n = num_task_queues(); 2829 for (uint i = 0; i < n; ++i) { 2830 task_queue(i)->stats.reset(); 2831 } 2832 } 2833 #endif // TASKQUEUE_STATS 2834 2835 void G1CollectedHeap::wait_for_root_region_scanning() { 2836 double scan_wait_start = os::elapsedTime(); 2837 // We have to wait until the CM threads finish scanning the 2838 // root regions as it's the only way to ensure that all the 2839 // objects on them have been correctly scanned before we start 2840 // moving them during the GC. 2841 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2842 double wait_time_ms = 0.0; 2843 if (waited) { 2844 double scan_wait_end = os::elapsedTime(); 2845 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2846 } 2847 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2848 } 2849 2850 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2851 private: 2852 G1HRPrinter* _hr_printer; 2853 public: 2854 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2855 2856 virtual bool do_heap_region(HeapRegion* r) { 2857 _hr_printer->cset(r); 2858 return false; 2859 } 2860 }; 2861 2862 void G1CollectedHeap::start_new_collection_set() { 2863 collection_set()->start_incremental_building(); 2864 2865 clear_cset_fast_test(); 2866 2867 guarantee(_eden.length() == 0, "eden should have been cleared"); 2868 g1_policy()->transfer_survivors_to_cset(survivor()); 2869 } 2870 2871 bool 2872 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2873 assert_at_safepoint_on_vm_thread(); 2874 guarantee(!is_gc_active(), "collection is not reentrant"); 2875 2876 if (GCLocker::check_active_before_gc()) { 2877 return false; 2878 } 2879 2880 _gc_timer_stw->register_gc_start(); 2881 2882 GCIdMark gc_id_mark; 2883 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2884 2885 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2886 ResourceMark rm; 2887 2888 g1_policy()->note_gc_start(); 2889 2890 wait_for_root_region_scanning(); 2891 2892 print_heap_before_gc(); 2893 print_heap_regions(); 2894 trace_heap_before_gc(_gc_tracer_stw); 2895 2896 _verifier->verify_region_sets_optional(); 2897 _verifier->verify_dirty_young_regions(); 2898 2899 // We should not be doing initial mark unless the conc mark thread is running 2900 if (!_cm_thread->should_terminate()) { 2901 // This call will decide whether this pause is an initial-mark 2902 // pause. If it is, in_initial_mark_gc() will return true 2903 // for the duration of this pause. 2904 g1_policy()->decide_on_conc_mark_initiation(); 2905 } 2906 2907 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2908 assert(!collector_state()->in_initial_mark_gc() || 2909 collector_state()->in_young_only_phase(), "sanity"); 2910 2911 // We also do not allow mixed GCs during marking. 2912 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2913 2914 // Record whether this pause is an initial mark. When the current 2915 // thread has completed its logging output and it's safe to signal 2916 // the CM thread, the flag's value in the policy has been reset. 2917 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2918 2919 // Inner scope for scope based logging, timers, and stats collection 2920 { 2921 EvacuationInfo evacuation_info; 2922 2923 if (collector_state()->in_initial_mark_gc()) { 2924 // We are about to start a marking cycle, so we increment the 2925 // full collection counter. 2926 increment_old_marking_cycles_started(); 2927 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2928 } 2929 2930 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2931 2932 GCTraceCPUTime tcpu; 2933 2934 G1HeapVerifier::G1VerifyType verify_type; 2935 FormatBuffer<> gc_string("Pause Young "); 2936 if (collector_state()->in_initial_mark_gc()) { 2937 gc_string.append("(Concurrent Start)"); 2938 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2939 } else if (collector_state()->in_young_only_phase()) { 2940 if (collector_state()->in_young_gc_before_mixed()) { 2941 gc_string.append("(Prepare Mixed)"); 2942 } else { 2943 gc_string.append("(Normal)"); 2944 } 2945 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2946 } else { 2947 gc_string.append("(Mixed)"); 2948 verify_type = G1HeapVerifier::G1VerifyMixed; 2949 } 2950 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2951 2952 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2953 workers()->active_workers(), 2954 Threads::number_of_non_daemon_threads()); 2955 active_workers = workers()->update_active_workers(active_workers); 2956 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2957 2958 G1MonitoringScope ms(g1mm(), 2959 false /* full_gc */, 2960 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2961 2962 G1HeapTransition heap_transition(this); 2963 size_t heap_used_bytes_before_gc = used(); 2964 2965 // Don't dynamically change the number of GC threads this early. A value of 2966 // 0 is used to indicate serial work. When parallel work is done, 2967 // it will be set. 2968 2969 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2970 IsGCActiveMark x; 2971 2972 gc_prologue(false); 2973 2974 if (VerifyRememberedSets) { 2975 log_info(gc, verify)("[Verifying RemSets before GC]"); 2976 VerifyRegionRemSetClosure v_cl; 2977 heap_region_iterate(&v_cl); 2978 } 2979 2980 _verifier->verify_before_gc(verify_type); 2981 2982 _verifier->check_bitmaps("GC Start"); 2983 2984 #if COMPILER2_OR_JVMCI 2985 DerivedPointerTable::clear(); 2986 #endif 2987 2988 // Please see comment in g1CollectedHeap.hpp and 2989 // G1CollectedHeap::ref_processing_init() to see how 2990 // reference processing currently works in G1. 2991 2992 // Enable discovery in the STW reference processor 2993 _ref_processor_stw->enable_discovery(); 2994 2995 { 2996 // We want to temporarily turn off discovery by the 2997 // CM ref processor, if necessary, and turn it back on 2998 // on again later if we do. Using a scoped 2999 // NoRefDiscovery object will do this. 3000 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3001 3002 // Forget the current alloc region (we might even choose it to be part 3003 // of the collection set!). 3004 _allocator->release_mutator_alloc_region(); 3005 3006 // This timing is only used by the ergonomics to handle our pause target. 3007 // It is unclear why this should not include the full pause. We will 3008 // investigate this in CR 7178365. 3009 // 3010 // Preserving the old comment here if that helps the investigation: 3011 // 3012 // The elapsed time induced by the start time below deliberately elides 3013 // the possible verification above. 3014 double sample_start_time_sec = os::elapsedTime(); 3015 3016 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3017 3018 if (collector_state()->in_initial_mark_gc()) { 3019 concurrent_mark()->pre_initial_mark(); 3020 } 3021 3022 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 3023 3024 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3025 3026 register_humongous_regions_with_cset(); 3027 3028 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3029 3030 // We call this after finalize_cset() to 3031 // ensure that the CSet has been finalized. 3032 _cm->verify_no_cset_oops(); 3033 3034 if (_hr_printer.is_active()) { 3035 G1PrintCollectionSetClosure cl(&_hr_printer); 3036 _collection_set.iterate(&cl); 3037 } 3038 3039 // Initialize the GC alloc regions. 3040 _allocator->init_gc_alloc_regions(evacuation_info); 3041 3042 G1ParScanThreadStateSet per_thread_states(this, 3043 workers()->active_workers(), 3044 collection_set()->young_region_length(), 3045 collection_set()->optional_region_length()); 3046 pre_evacuate_collection_set(); 3047 3048 // Actually do the work... 3049 evacuate_collection_set(&per_thread_states); 3050 evacuate_optional_collection_set(&per_thread_states); 3051 3052 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3053 3054 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3055 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3056 3057 eagerly_reclaim_humongous_regions(); 3058 3059 record_obj_copy_mem_stats(); 3060 _survivor_evac_stats.adjust_desired_plab_sz(); 3061 _old_evac_stats.adjust_desired_plab_sz(); 3062 3063 double start = os::elapsedTime(); 3064 start_new_collection_set(); 3065 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3066 3067 if (evacuation_failed()) { 3068 double recalculate_used_start = os::elapsedTime(); 3069 set_used(recalculate_used()); 3070 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3071 3072 if (_archive_allocator != NULL) { 3073 _archive_allocator->clear_used(); 3074 } 3075 for (uint i = 0; i < ParallelGCThreads; i++) { 3076 if (_evacuation_failed_info_array[i].has_failed()) { 3077 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3078 } 3079 } 3080 } else { 3081 // The "used" of the the collection set have already been subtracted 3082 // when they were freed. Add in the bytes evacuated. 3083 increase_used(g1_policy()->bytes_copied_during_gc()); 3084 } 3085 3086 if (collector_state()->in_initial_mark_gc()) { 3087 // We have to do this before we notify the CM threads that 3088 // they can start working to make sure that all the 3089 // appropriate initialization is done on the CM object. 3090 concurrent_mark()->post_initial_mark(); 3091 // Note that we don't actually trigger the CM thread at 3092 // this point. We do that later when we're sure that 3093 // the current thread has completed its logging output. 3094 } 3095 3096 allocate_dummy_regions(); 3097 3098 _allocator->init_mutator_alloc_region(); 3099 3100 { 3101 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3102 if (expand_bytes > 0) { 3103 size_t bytes_before = capacity(); 3104 // No need for an ergo logging here, 3105 // expansion_amount() does this when it returns a value > 0. 3106 double expand_ms; 3107 if (!expand(expand_bytes, _workers, &expand_ms)) { 3108 // We failed to expand the heap. Cannot do anything about it. 3109 } 3110 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3111 } 3112 } 3113 3114 // We redo the verification but now wrt to the new CSet which 3115 // has just got initialized after the previous CSet was freed. 3116 _cm->verify_no_cset_oops(); 3117 3118 // This timing is only used by the ergonomics to handle our pause target. 3119 // It is unclear why this should not include the full pause. We will 3120 // investigate this in CR 7178365. 3121 double sample_end_time_sec = os::elapsedTime(); 3122 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3123 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3124 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3125 3126 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3127 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3128 3129 if (VerifyRememberedSets) { 3130 log_info(gc, verify)("[Verifying RemSets after GC]"); 3131 VerifyRegionRemSetClosure v_cl; 3132 heap_region_iterate(&v_cl); 3133 } 3134 3135 _verifier->verify_after_gc(verify_type); 3136 _verifier->check_bitmaps("GC End"); 3137 3138 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3139 _ref_processor_stw->verify_no_references_recorded(); 3140 3141 // CM reference discovery will be re-enabled if necessary. 3142 } 3143 3144 #ifdef TRACESPINNING 3145 ParallelTaskTerminator::print_termination_counts(); 3146 #endif 3147 3148 gc_epilogue(false); 3149 } 3150 3151 // Print the remainder of the GC log output. 3152 if (evacuation_failed()) { 3153 log_info(gc)("To-space exhausted"); 3154 } 3155 3156 g1_policy()->print_phases(); 3157 heap_transition.print(); 3158 3159 // It is not yet to safe to tell the concurrent mark to 3160 // start as we have some optional output below. We don't want the 3161 // output from the concurrent mark thread interfering with this 3162 // logging output either. 3163 3164 _hrm->verify_optional(); 3165 _verifier->verify_region_sets_optional(); 3166 3167 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3168 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3169 3170 print_heap_after_gc(); 3171 print_heap_regions(); 3172 trace_heap_after_gc(_gc_tracer_stw); 3173 3174 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3175 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3176 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3177 // before any GC notifications are raised. 3178 g1mm()->update_sizes(); 3179 3180 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3181 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3182 _gc_timer_stw->register_gc_end(); 3183 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3184 } 3185 // It should now be safe to tell the concurrent mark thread to start 3186 // without its logging output interfering with the logging output 3187 // that came from the pause. 3188 3189 if (should_start_conc_mark) { 3190 // CAUTION: after the doConcurrentMark() call below, 3191 // the concurrent marking thread(s) could be running 3192 // concurrently with us. Make sure that anything after 3193 // this point does not assume that we are the only GC thread 3194 // running. Note: of course, the actual marking work will 3195 // not start until the safepoint itself is released in 3196 // SuspendibleThreadSet::desynchronize(). 3197 do_concurrent_mark(); 3198 } 3199 3200 return true; 3201 } 3202 3203 void G1CollectedHeap::remove_self_forwarding_pointers() { 3204 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3205 workers()->run_task(&rsfp_task); 3206 } 3207 3208 void G1CollectedHeap::restore_after_evac_failure() { 3209 double remove_self_forwards_start = os::elapsedTime(); 3210 3211 remove_self_forwarding_pointers(); 3212 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3213 _preserved_marks_set.restore(&task_executor); 3214 3215 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3216 } 3217 3218 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3219 if (!_evacuation_failed) { 3220 _evacuation_failed = true; 3221 } 3222 3223 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3224 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3225 } 3226 3227 bool G1ParEvacuateFollowersClosure::offer_termination() { 3228 EventGCPhaseParallel event; 3229 G1ParScanThreadState* const pss = par_scan_state(); 3230 start_term_time(); 3231 const bool res = terminator()->offer_termination(); 3232 end_term_time(); 3233 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3234 return res; 3235 } 3236 3237 void G1ParEvacuateFollowersClosure::do_void() { 3238 EventGCPhaseParallel event; 3239 G1ParScanThreadState* const pss = par_scan_state(); 3240 pss->trim_queue(); 3241 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3242 do { 3243 EventGCPhaseParallel event; 3244 pss->steal_and_trim_queue(queues()); 3245 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3246 } while (!offer_termination()); 3247 } 3248 3249 class G1ParTask : public AbstractGangTask { 3250 protected: 3251 G1CollectedHeap* _g1h; 3252 G1ParScanThreadStateSet* _pss; 3253 RefToScanQueueSet* _queues; 3254 G1RootProcessor* _root_processor; 3255 TaskTerminator _terminator; 3256 uint _n_workers; 3257 3258 public: 3259 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3260 : AbstractGangTask("G1 collection"), 3261 _g1h(g1h), 3262 _pss(per_thread_states), 3263 _queues(task_queues), 3264 _root_processor(root_processor), 3265 _terminator(n_workers, _queues), 3266 _n_workers(n_workers) 3267 {} 3268 3269 void work(uint worker_id) { 3270 if (worker_id >= _n_workers) return; // no work needed this round 3271 3272 double start_sec = os::elapsedTime(); 3273 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3274 3275 { 3276 ResourceMark rm; 3277 HandleMark hm; 3278 3279 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3280 3281 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3282 pss->set_ref_discoverer(rp); 3283 3284 double start_strong_roots_sec = os::elapsedTime(); 3285 3286 _root_processor->evacuate_roots(pss, worker_id); 3287 3288 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3289 // treating the nmethods visited to act as roots for concurrent marking. 3290 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3291 // objects copied by the current evacuation. 3292 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3293 3294 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3295 3296 double term_sec = 0.0; 3297 size_t evac_term_attempts = 0; 3298 { 3299 double start = os::elapsedTime(); 3300 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy); 3301 evac.do_void(); 3302 3303 evac_term_attempts = evac.term_attempts(); 3304 term_sec = evac.term_time(); 3305 double elapsed_sec = os::elapsedTime() - start; 3306 3307 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3308 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3309 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3310 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3311 } 3312 3313 assert(pss->queue_is_empty(), "should be empty"); 3314 3315 if (log_is_enabled(Debug, gc, task, stats)) { 3316 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3317 size_t lab_waste; 3318 size_t lab_undo_waste; 3319 pss->waste(lab_waste, lab_undo_waste); 3320 _g1h->print_termination_stats(worker_id, 3321 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3322 strong_roots_sec * 1000.0, /* strong roots time */ 3323 term_sec * 1000.0, /* evac term time */ 3324 evac_term_attempts, /* evac term attempts */ 3325 lab_waste, /* alloc buffer waste */ 3326 lab_undo_waste /* undo waste */ 3327 ); 3328 } 3329 3330 // Close the inner scope so that the ResourceMark and HandleMark 3331 // destructors are executed here and are included as part of the 3332 // "GC Worker Time". 3333 } 3334 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3335 } 3336 }; 3337 3338 void G1CollectedHeap::print_termination_stats_hdr() { 3339 log_debug(gc, task, stats)("GC Termination Stats"); 3340 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3341 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3342 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3343 } 3344 3345 void G1CollectedHeap::print_termination_stats(uint worker_id, 3346 double elapsed_ms, 3347 double strong_roots_ms, 3348 double term_ms, 3349 size_t term_attempts, 3350 size_t alloc_buffer_waste, 3351 size_t undo_waste) const { 3352 log_debug(gc, task, stats) 3353 ("%3d %9.2f %9.2f %6.2f " 3354 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3355 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3356 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3357 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3358 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3359 alloc_buffer_waste * HeapWordSize / K, 3360 undo_waste * HeapWordSize / K); 3361 } 3362 3363 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3364 bool class_unloading_occurred) { 3365 uint num_workers = workers()->active_workers(); 3366 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3367 workers()->run_task(&unlink_task); 3368 } 3369 3370 // Clean string dedup data structures. 3371 class G1PartialCleaningTask : public AbstractGangTask { 3372 BoolObjectClosure* _is_alive; 3373 OopClosure* _keep_alive; 3374 bool _do_dedup_table; 3375 G1GCPhaseTimes* _phase_times; 3376 3377 public: 3378 G1PartialCleaningTask(BoolObjectClosure* is_alive, 3379 OopClosure* keep_alive, 3380 bool do_dedup_table, 3381 G1GCPhaseTimes* phase_times) : 3382 AbstractGangTask("Partial Cleaning Task"), 3383 _is_alive(is_alive), 3384 _keep_alive(keep_alive), 3385 _do_dedup_table(do_dedup_table), 3386 _phase_times(phase_times) 3387 { 3388 assert(_do_dedup_table, "Should only be executed when there is something to do"); 3389 StringDedup::gc_prologue(true); 3390 } 3391 3392 ~G1PartialCleaningTask() { 3393 StringDedup::gc_epilogue(); 3394 } 3395 3396 void work(uint worker_id) { 3397 // Ideally we would use a StringDedupCleaningTask here, but since we want to 3398 // take the time we need to copy the code here. 3399 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3400 { 3401 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3402 StringDedupQueue::unlink_or_oops_do(&cl); 3403 } 3404 { 3405 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3406 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3407 } 3408 } 3409 }; 3410 3411 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3412 OopClosure* keep_alive, 3413 bool process_dedup_table, 3414 G1GCPhaseTimes* phase_times) { 3415 if (!process_dedup_table) { 3416 // Nothing to clean. 3417 return; 3418 } 3419 3420 G1PartialCleaningTask cl(is_alive, 3421 keep_alive, 3422 process_dedup_table, 3423 phase_times); 3424 workers()->run_task(&cl); 3425 } 3426 3427 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3428 private: 3429 DirtyCardQueueSet* _queue; 3430 G1CollectedHeap* _g1h; 3431 public: 3432 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3433 _queue(queue), _g1h(g1h) { } 3434 3435 virtual void work(uint worker_id) { 3436 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3437 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3438 3439 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3440 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3441 3442 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3443 } 3444 }; 3445 3446 void G1CollectedHeap::redirty_logged_cards() { 3447 double redirty_logged_cards_start = os::elapsedTime(); 3448 3449 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3450 dirty_card_queue_set().reset_for_par_iteration(); 3451 workers()->run_task(&redirty_task); 3452 3453 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3454 dcq.merge_bufferlists(&dirty_card_queue_set()); 3455 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3456 3457 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3458 } 3459 3460 // Weak Reference Processing support 3461 3462 bool G1STWIsAliveClosure::do_object_b(oop p) { 3463 // An object is reachable if it is outside the collection set, 3464 // or is inside and copied. 3465 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3466 } 3467 3468 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3469 assert(obj != NULL, "must not be NULL"); 3470 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3471 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3472 // may falsely indicate that this is not the case here: however the collection set only 3473 // contains old regions when concurrent mark is not running. 3474 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3475 } 3476 3477 // Non Copying Keep Alive closure 3478 class G1KeepAliveClosure: public OopClosure { 3479 G1CollectedHeap*_g1h; 3480 public: 3481 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3482 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3483 void do_oop(oop* p) { 3484 oop obj = *p; 3485 assert(obj != NULL, "the caller should have filtered out NULL values"); 3486 3487 const InCSetState cset_state =_g1h->in_cset_state(obj); 3488 if (!cset_state.is_in_cset_or_humongous()) { 3489 return; 3490 } 3491 if (cset_state.is_in_cset()) { 3492 assert( obj->is_forwarded(), "invariant" ); 3493 *p = obj->forwardee(); 3494 } else { 3495 assert(!obj->is_forwarded(), "invariant" ); 3496 assert(cset_state.is_humongous(), 3497 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3498 _g1h->set_humongous_is_live(obj); 3499 } 3500 } 3501 }; 3502 3503 // Copying Keep Alive closure - can be called from both 3504 // serial and parallel code as long as different worker 3505 // threads utilize different G1ParScanThreadState instances 3506 // and different queues. 3507 3508 class G1CopyingKeepAliveClosure: public OopClosure { 3509 G1CollectedHeap* _g1h; 3510 G1ParScanThreadState* _par_scan_state; 3511 3512 public: 3513 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3514 G1ParScanThreadState* pss): 3515 _g1h(g1h), 3516 _par_scan_state(pss) 3517 {} 3518 3519 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3520 virtual void do_oop( oop* p) { do_oop_work(p); } 3521 3522 template <class T> void do_oop_work(T* p) { 3523 oop obj = RawAccess<>::oop_load(p); 3524 3525 if (_g1h->is_in_cset_or_humongous(obj)) { 3526 // If the referent object has been forwarded (either copied 3527 // to a new location or to itself in the event of an 3528 // evacuation failure) then we need to update the reference 3529 // field and, if both reference and referent are in the G1 3530 // heap, update the RSet for the referent. 3531 // 3532 // If the referent has not been forwarded then we have to keep 3533 // it alive by policy. Therefore we have copy the referent. 3534 // 3535 // When the queue is drained (after each phase of reference processing) 3536 // the object and it's followers will be copied, the reference field set 3537 // to point to the new location, and the RSet updated. 3538 _par_scan_state->push_on_queue(p); 3539 } 3540 } 3541 }; 3542 3543 // Serial drain queue closure. Called as the 'complete_gc' 3544 // closure for each discovered list in some of the 3545 // reference processing phases. 3546 3547 class G1STWDrainQueueClosure: public VoidClosure { 3548 protected: 3549 G1CollectedHeap* _g1h; 3550 G1ParScanThreadState* _par_scan_state; 3551 3552 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3553 3554 public: 3555 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3556 _g1h(g1h), 3557 _par_scan_state(pss) 3558 { } 3559 3560 void do_void() { 3561 G1ParScanThreadState* const pss = par_scan_state(); 3562 pss->trim_queue(); 3563 } 3564 }; 3565 3566 // Parallel Reference Processing closures 3567 3568 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3569 // processing during G1 evacuation pauses. 3570 3571 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3572 private: 3573 G1CollectedHeap* _g1h; 3574 G1ParScanThreadStateSet* _pss; 3575 RefToScanQueueSet* _queues; 3576 WorkGang* _workers; 3577 3578 public: 3579 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3580 G1ParScanThreadStateSet* per_thread_states, 3581 WorkGang* workers, 3582 RefToScanQueueSet *task_queues) : 3583 _g1h(g1h), 3584 _pss(per_thread_states), 3585 _queues(task_queues), 3586 _workers(workers) 3587 { 3588 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3589 } 3590 3591 // Executes the given task using concurrent marking worker threads. 3592 virtual void execute(ProcessTask& task, uint ergo_workers); 3593 }; 3594 3595 // Gang task for possibly parallel reference processing 3596 3597 class G1STWRefProcTaskProxy: public AbstractGangTask { 3598 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3599 ProcessTask& _proc_task; 3600 G1CollectedHeap* _g1h; 3601 G1ParScanThreadStateSet* _pss; 3602 RefToScanQueueSet* _task_queues; 3603 ParallelTaskTerminator* _terminator; 3604 3605 public: 3606 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3607 G1CollectedHeap* g1h, 3608 G1ParScanThreadStateSet* per_thread_states, 3609 RefToScanQueueSet *task_queues, 3610 ParallelTaskTerminator* terminator) : 3611 AbstractGangTask("Process reference objects in parallel"), 3612 _proc_task(proc_task), 3613 _g1h(g1h), 3614 _pss(per_thread_states), 3615 _task_queues(task_queues), 3616 _terminator(terminator) 3617 {} 3618 3619 virtual void work(uint worker_id) { 3620 // The reference processing task executed by a single worker. 3621 ResourceMark rm; 3622 HandleMark hm; 3623 3624 G1STWIsAliveClosure is_alive(_g1h); 3625 3626 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3627 pss->set_ref_discoverer(NULL); 3628 3629 // Keep alive closure. 3630 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3631 3632 // Complete GC closure 3633 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3634 3635 // Call the reference processing task's work routine. 3636 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3637 3638 // Note we cannot assert that the refs array is empty here as not all 3639 // of the processing tasks (specifically phase2 - pp2_work) execute 3640 // the complete_gc closure (which ordinarily would drain the queue) so 3641 // the queue may not be empty. 3642 } 3643 }; 3644 3645 // Driver routine for parallel reference processing. 3646 // Creates an instance of the ref processing gang 3647 // task and has the worker threads execute it. 3648 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3649 assert(_workers != NULL, "Need parallel worker threads."); 3650 3651 assert(_workers->active_workers() >= ergo_workers, 3652 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3653 ergo_workers, _workers->active_workers()); 3654 TaskTerminator terminator(ergo_workers, _queues); 3655 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3656 3657 _workers->run_task(&proc_task_proxy, ergo_workers); 3658 } 3659 3660 // End of weak reference support closures 3661 3662 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3663 double ref_proc_start = os::elapsedTime(); 3664 3665 ReferenceProcessor* rp = _ref_processor_stw; 3666 assert(rp->discovery_enabled(), "should have been enabled"); 3667 3668 // Closure to test whether a referent is alive. 3669 G1STWIsAliveClosure is_alive(this); 3670 3671 // Even when parallel reference processing is enabled, the processing 3672 // of JNI refs is serial and performed serially by the current thread 3673 // rather than by a worker. The following PSS will be used for processing 3674 // JNI refs. 3675 3676 // Use only a single queue for this PSS. 3677 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3678 pss->set_ref_discoverer(NULL); 3679 assert(pss->queue_is_empty(), "pre-condition"); 3680 3681 // Keep alive closure. 3682 G1CopyingKeepAliveClosure keep_alive(this, pss); 3683 3684 // Serial Complete GC closure 3685 G1STWDrainQueueClosure drain_queue(this, pss); 3686 3687 // Setup the soft refs policy... 3688 rp->setup_policy(false); 3689 3690 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3691 3692 ReferenceProcessorStats stats; 3693 if (!rp->processing_is_mt()) { 3694 // Serial reference processing... 3695 stats = rp->process_discovered_references(&is_alive, 3696 &keep_alive, 3697 &drain_queue, 3698 NULL, 3699 pt); 3700 } else { 3701 uint no_of_gc_workers = workers()->active_workers(); 3702 3703 // Parallel reference processing 3704 assert(no_of_gc_workers <= rp->max_num_queues(), 3705 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3706 no_of_gc_workers, rp->max_num_queues()); 3707 3708 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3709 stats = rp->process_discovered_references(&is_alive, 3710 &keep_alive, 3711 &drain_queue, 3712 &par_task_executor, 3713 pt); 3714 } 3715 3716 _gc_tracer_stw->report_gc_reference_stats(stats); 3717 3718 // We have completed copying any necessary live referent objects. 3719 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3720 3721 make_pending_list_reachable(); 3722 3723 rp->verify_no_references_recorded(); 3724 3725 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3726 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3727 } 3728 3729 void G1CollectedHeap::make_pending_list_reachable() { 3730 if (collector_state()->in_initial_mark_gc()) { 3731 oop pll_head = Universe::reference_pending_list(); 3732 if (pll_head != NULL) { 3733 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3734 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3735 } 3736 } 3737 } 3738 3739 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3740 double merge_pss_time_start = os::elapsedTime(); 3741 per_thread_states->flush(); 3742 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3743 } 3744 3745 void G1CollectedHeap::pre_evacuate_collection_set() { 3746 _expand_heap_after_alloc_failure = true; 3747 _evacuation_failed = false; 3748 3749 // Disable the hot card cache. 3750 _hot_card_cache->reset_hot_cache_claimed_index(); 3751 _hot_card_cache->set_use_cache(false); 3752 3753 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3754 _preserved_marks_set.assert_empty(); 3755 3756 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3757 3758 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3759 if (collector_state()->in_initial_mark_gc()) { 3760 double start_clear_claimed_marks = os::elapsedTime(); 3761 3762 ClassLoaderDataGraph::clear_claimed_marks(); 3763 3764 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3765 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3766 } 3767 } 3768 3769 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3770 // Should G1EvacuationFailureALot be in effect for this GC? 3771 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3772 3773 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3774 3775 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3776 3777 double start_par_time_sec = os::elapsedTime(); 3778 double end_par_time_sec; 3779 3780 { 3781 const uint n_workers = workers()->active_workers(); 3782 G1RootProcessor root_processor(this, n_workers); 3783 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3784 3785 print_termination_stats_hdr(); 3786 3787 workers()->run_task(&g1_par_task); 3788 end_par_time_sec = os::elapsedTime(); 3789 3790 // Closing the inner scope will execute the destructor 3791 // for the G1RootProcessor object. We record the current 3792 // elapsed time before closing the scope so that time 3793 // taken for the destructor is NOT included in the 3794 // reported parallel time. 3795 } 3796 3797 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3798 phase_times->record_par_time(par_time_ms); 3799 3800 double code_root_fixup_time_ms = 3801 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3802 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 3803 } 3804 3805 class G1EvacuateOptionalRegionTask : public AbstractGangTask { 3806 G1CollectedHeap* _g1h; 3807 G1ParScanThreadStateSet* _per_thread_states; 3808 G1OptionalCSet* _optional; 3809 RefToScanQueueSet* _queues; 3810 ParallelTaskTerminator _terminator; 3811 3812 Tickspan trim_ticks(G1ParScanThreadState* pss) { 3813 Tickspan copy_time = pss->trim_ticks(); 3814 pss->reset_trim_ticks(); 3815 return copy_time; 3816 } 3817 3818 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3819 G1EvacuationRootClosures* root_cls = pss->closures(); 3820 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss); 3821 3822 size_t scanned = 0; 3823 size_t claimed = 0; 3824 size_t skipped = 0; 3825 size_t used_memory = 0; 3826 3827 Ticks start = Ticks::now(); 3828 Tickspan copy_time; 3829 3830 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) { 3831 HeapRegion* hr = _optional->region_at(i); 3832 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl); 3833 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops()); 3834 copy_time += trim_ticks(pss); 3835 3836 G1ScanRSForRegionClosure scan_rs_cl(_g1h->g1_rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id); 3837 scan_rs_cl.do_heap_region(hr); 3838 copy_time += trim_ticks(pss); 3839 scanned += scan_rs_cl.cards_scanned(); 3840 claimed += scan_rs_cl.cards_claimed(); 3841 skipped += scan_rs_cl.cards_skipped(); 3842 3843 // Chunk lists for this region is no longer needed. 3844 used_memory += pss->oops_into_optional_region(hr)->used_memory(); 3845 } 3846 3847 Tickspan scan_time = (Ticks::now() - start) - copy_time; 3848 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3849 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds()); 3850 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds()); 3851 3852 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards); 3853 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards); 3854 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards); 3855 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory); 3856 } 3857 3858 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3859 Ticks start = Ticks::now(); 3860 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy); 3861 cl.do_void(); 3862 3863 Tickspan evac_time = (Ticks::now() - start); 3864 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3865 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds()); 3866 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation"); 3867 } 3868 3869 public: 3870 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h, 3871 G1ParScanThreadStateSet* per_thread_states, 3872 G1OptionalCSet* cset, 3873 RefToScanQueueSet* queues, 3874 uint n_workers) : 3875 AbstractGangTask("G1 Evacuation Optional Region Task"), 3876 _g1h(g1h), 3877 _per_thread_states(per_thread_states), 3878 _optional(cset), 3879 _queues(queues), 3880 _terminator(n_workers, _queues) { 3881 } 3882 3883 void work(uint worker_id) { 3884 ResourceMark rm; 3885 HandleMark hm; 3886 3887 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3888 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3889 3890 scan_roots(pss, worker_id); 3891 evacuate_live_objects(pss, worker_id); 3892 } 3893 }; 3894 3895 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) { 3896 class G1MarkScope : public MarkScope {}; 3897 G1MarkScope code_mark_scope; 3898 3899 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers()); 3900 workers()->run_task(&task); 3901 } 3902 3903 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3904 G1OptionalCSet optional_cset(&_collection_set, per_thread_states); 3905 if (optional_cset.is_empty()) { 3906 return; 3907 } 3908 3909 if (evacuation_failed()) { 3910 return; 3911 } 3912 3913 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3914 const double gc_start_time_ms = phase_times->cur_collection_start_sec() * 1000.0; 3915 3916 double start_time_sec = os::elapsedTime(); 3917 3918 do { 3919 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3920 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3921 3922 if (time_left_ms < 0) { 3923 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms); 3924 break; 3925 } 3926 3927 optional_cset.prepare_evacuation(time_left_ms * _g1_policy->optional_evacuation_fraction()); 3928 if (optional_cset.prepare_failed()) { 3929 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms); 3930 break; 3931 } 3932 3933 evacuate_optional_regions(per_thread_states, &optional_cset); 3934 3935 optional_cset.complete_evacuation(); 3936 if (optional_cset.evacuation_failed()) { 3937 break; 3938 } 3939 } while (!optional_cset.is_empty()); 3940 3941 phase_times->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0); 3942 } 3943 3944 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3945 // Also cleans the card table from temporary duplicate detection information used 3946 // during UpdateRS/ScanRS. 3947 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 3948 3949 // Process any discovered reference objects - we have 3950 // to do this _before_ we retire the GC alloc regions 3951 // as we may have to copy some 'reachable' referent 3952 // objects (and their reachable sub-graphs) that were 3953 // not copied during the pause. 3954 process_discovered_references(per_thread_states); 3955 3956 G1STWIsAliveClosure is_alive(this); 3957 G1KeepAliveClosure keep_alive(this); 3958 3959 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3960 g1_policy()->phase_times()->weak_phase_times()); 3961 3962 { 3963 double cleaning_start = os::elapsedTime(); 3964 3965 partial_cleaning(&is_alive, 3966 &keep_alive, 3967 G1StringDedup::is_enabled() /* process_dedup_table */, 3968 g1_policy()->phase_times()); 3969 3970 double cleaning_time_ms = (os::elapsedTime() - cleaning_start) * 1000.0; 3971 g1_policy()->phase_times()->record_string_deduplication_time(cleaning_time_ms); 3972 } 3973 3974 if (evacuation_failed()) { 3975 restore_after_evac_failure(); 3976 3977 // Reset the G1EvacuationFailureALot counters and flags 3978 // Note: the values are reset only when an actual 3979 // evacuation failure occurs. 3980 NOT_PRODUCT(reset_evacuation_should_fail();) 3981 } 3982 3983 _preserved_marks_set.assert_empty(); 3984 3985 _allocator->release_gc_alloc_regions(evacuation_info); 3986 3987 merge_per_thread_state_info(per_thread_states); 3988 3989 // Reset and re-enable the hot card cache. 3990 // Note the counts for the cards in the regions in the 3991 // collection set are reset when the collection set is freed. 3992 _hot_card_cache->reset_hot_cache(); 3993 _hot_card_cache->set_use_cache(true); 3994 3995 purge_code_root_memory(); 3996 3997 redirty_logged_cards(); 3998 #if COMPILER2_OR_JVMCI 3999 double start = os::elapsedTime(); 4000 DerivedPointerTable::update_pointers(); 4001 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4002 #endif 4003 g1_policy()->print_age_table(); 4004 } 4005 4006 void G1CollectedHeap::record_obj_copy_mem_stats() { 4007 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4008 4009 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4010 create_g1_evac_summary(&_old_evac_stats)); 4011 } 4012 4013 void G1CollectedHeap::free_region(HeapRegion* hr, 4014 FreeRegionList* free_list, 4015 bool skip_remset, 4016 bool skip_hot_card_cache, 4017 bool locked) { 4018 assert(!hr->is_free(), "the region should not be free"); 4019 assert(!hr->is_empty(), "the region should not be empty"); 4020 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4021 assert(free_list != NULL, "pre-condition"); 4022 4023 if (G1VerifyBitmaps) { 4024 MemRegion mr(hr->bottom(), hr->end()); 4025 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4026 } 4027 4028 // Clear the card counts for this region. 4029 // Note: we only need to do this if the region is not young 4030 // (since we don't refine cards in young regions). 4031 if (!skip_hot_card_cache && !hr->is_young()) { 4032 _hot_card_cache->reset_card_counts(hr); 4033 } 4034 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4035 _g1_policy->remset_tracker()->update_at_free(hr); 4036 free_list->add_ordered(hr); 4037 } 4038 4039 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4040 FreeRegionList* free_list) { 4041 assert(hr->is_humongous(), "this is only for humongous regions"); 4042 assert(free_list != NULL, "pre-condition"); 4043 hr->clear_humongous(); 4044 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 4045 } 4046 4047 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4048 const uint humongous_regions_removed) { 4049 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4050 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4051 _old_set.bulk_remove(old_regions_removed); 4052 _humongous_set.bulk_remove(humongous_regions_removed); 4053 } 4054 4055 } 4056 4057 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4058 assert(list != NULL, "list can't be null"); 4059 if (!list->is_empty()) { 4060 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4061 _hrm->insert_list_into_free_list(list); 4062 } 4063 } 4064 4065 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4066 decrease_used(bytes); 4067 } 4068 4069 class G1FreeCollectionSetTask : public AbstractGangTask { 4070 private: 4071 4072 // Closure applied to all regions in the collection set to do work that needs to 4073 // be done serially in a single thread. 4074 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4075 private: 4076 EvacuationInfo* _evacuation_info; 4077 const size_t* _surviving_young_words; 4078 4079 // Bytes used in successfully evacuated regions before the evacuation. 4080 size_t _before_used_bytes; 4081 // Bytes used in unsucessfully evacuated regions before the evacuation 4082 size_t _after_used_bytes; 4083 4084 size_t _bytes_allocated_in_old_since_last_gc; 4085 4086 size_t _failure_used_words; 4087 size_t _failure_waste_words; 4088 4089 FreeRegionList _local_free_list; 4090 public: 4091 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4092 HeapRegionClosure(), 4093 _evacuation_info(evacuation_info), 4094 _surviving_young_words(surviving_young_words), 4095 _before_used_bytes(0), 4096 _after_used_bytes(0), 4097 _bytes_allocated_in_old_since_last_gc(0), 4098 _failure_used_words(0), 4099 _failure_waste_words(0), 4100 _local_free_list("Local Region List for CSet Freeing") { 4101 } 4102 4103 virtual bool do_heap_region(HeapRegion* r) { 4104 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4105 4106 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4107 g1h->clear_in_cset(r); 4108 4109 if (r->is_young()) { 4110 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4111 "Young index %d is wrong for region %u of type %s with %u young regions", 4112 r->young_index_in_cset(), 4113 r->hrm_index(), 4114 r->get_type_str(), 4115 g1h->collection_set()->young_region_length()); 4116 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4117 r->record_surv_words_in_group(words_survived); 4118 } 4119 4120 if (!r->evacuation_failed()) { 4121 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4122 _before_used_bytes += r->used(); 4123 g1h->free_region(r, 4124 &_local_free_list, 4125 true, /* skip_remset */ 4126 true, /* skip_hot_card_cache */ 4127 true /* locked */); 4128 } else { 4129 r->uninstall_surv_rate_group(); 4130 r->set_young_index_in_cset(-1); 4131 r->set_evacuation_failed(false); 4132 // When moving a young gen region to old gen, we "allocate" that whole region 4133 // there. This is in addition to any already evacuated objects. Notify the 4134 // policy about that. 4135 // Old gen regions do not cause an additional allocation: both the objects 4136 // still in the region and the ones already moved are accounted for elsewhere. 4137 if (r->is_young()) { 4138 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4139 } 4140 // The region is now considered to be old. 4141 r->set_old(); 4142 // Do some allocation statistics accounting. Regions that failed evacuation 4143 // are always made old, so there is no need to update anything in the young 4144 // gen statistics, but we need to update old gen statistics. 4145 size_t used_words = r->marked_bytes() / HeapWordSize; 4146 4147 _failure_used_words += used_words; 4148 _failure_waste_words += HeapRegion::GrainWords - used_words; 4149 4150 g1h->old_set_add(r); 4151 _after_used_bytes += r->used(); 4152 } 4153 return false; 4154 } 4155 4156 void complete_work() { 4157 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4158 4159 _evacuation_info->set_regions_freed(_local_free_list.length()); 4160 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4161 4162 g1h->prepend_to_freelist(&_local_free_list); 4163 g1h->decrement_summary_bytes(_before_used_bytes); 4164 4165 G1Policy* policy = g1h->g1_policy(); 4166 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4167 4168 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4169 } 4170 }; 4171 4172 G1CollectionSet* _collection_set; 4173 G1SerialFreeCollectionSetClosure _cl; 4174 const size_t* _surviving_young_words; 4175 4176 size_t _rs_lengths; 4177 4178 volatile jint _serial_work_claim; 4179 4180 struct WorkItem { 4181 uint region_idx; 4182 bool is_young; 4183 bool evacuation_failed; 4184 4185 WorkItem(HeapRegion* r) { 4186 region_idx = r->hrm_index(); 4187 is_young = r->is_young(); 4188 evacuation_failed = r->evacuation_failed(); 4189 } 4190 }; 4191 4192 volatile size_t _parallel_work_claim; 4193 size_t _num_work_items; 4194 WorkItem* _work_items; 4195 4196 void do_serial_work() { 4197 // Need to grab the lock to be allowed to modify the old region list. 4198 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4199 _collection_set->iterate(&_cl); 4200 } 4201 4202 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4203 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4204 4205 HeapRegion* r = g1h->region_at(region_idx); 4206 assert(!g1h->is_on_master_free_list(r), "sanity"); 4207 4208 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4209 4210 if (!is_young) { 4211 g1h->_hot_card_cache->reset_card_counts(r); 4212 } 4213 4214 if (!evacuation_failed) { 4215 r->rem_set()->clear_locked(); 4216 } 4217 } 4218 4219 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4220 private: 4221 size_t _cur_idx; 4222 WorkItem* _work_items; 4223 public: 4224 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4225 4226 virtual bool do_heap_region(HeapRegion* r) { 4227 _work_items[_cur_idx++] = WorkItem(r); 4228 return false; 4229 } 4230 }; 4231 4232 void prepare_work() { 4233 G1PrepareFreeCollectionSetClosure cl(_work_items); 4234 _collection_set->iterate(&cl); 4235 } 4236 4237 void complete_work() { 4238 _cl.complete_work(); 4239 4240 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4241 policy->record_max_rs_lengths(_rs_lengths); 4242 policy->cset_regions_freed(); 4243 } 4244 public: 4245 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4246 AbstractGangTask("G1 Free Collection Set"), 4247 _collection_set(collection_set), 4248 _cl(evacuation_info, surviving_young_words), 4249 _surviving_young_words(surviving_young_words), 4250 _rs_lengths(0), 4251 _serial_work_claim(0), 4252 _parallel_work_claim(0), 4253 _num_work_items(collection_set->region_length()), 4254 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4255 prepare_work(); 4256 } 4257 4258 ~G1FreeCollectionSetTask() { 4259 complete_work(); 4260 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4261 } 4262 4263 // Chunk size for work distribution. The chosen value has been determined experimentally 4264 // to be a good tradeoff between overhead and achievable parallelism. 4265 static uint chunk_size() { return 32; } 4266 4267 virtual void work(uint worker_id) { 4268 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4269 4270 // Claim serial work. 4271 if (_serial_work_claim == 0) { 4272 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4273 if (value == 0) { 4274 double serial_time = os::elapsedTime(); 4275 do_serial_work(); 4276 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4277 } 4278 } 4279 4280 // Start parallel work. 4281 double young_time = 0.0; 4282 bool has_young_time = false; 4283 double non_young_time = 0.0; 4284 bool has_non_young_time = false; 4285 4286 while (true) { 4287 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4288 size_t cur = end - chunk_size(); 4289 4290 if (cur >= _num_work_items) { 4291 break; 4292 } 4293 4294 EventGCPhaseParallel event; 4295 double start_time = os::elapsedTime(); 4296 4297 end = MIN2(end, _num_work_items); 4298 4299 for (; cur < end; cur++) { 4300 bool is_young = _work_items[cur].is_young; 4301 4302 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4303 4304 double end_time = os::elapsedTime(); 4305 double time_taken = end_time - start_time; 4306 if (is_young) { 4307 young_time += time_taken; 4308 has_young_time = true; 4309 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4310 } else { 4311 non_young_time += time_taken; 4312 has_non_young_time = true; 4313 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4314 } 4315 start_time = end_time; 4316 } 4317 } 4318 4319 if (has_young_time) { 4320 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4321 } 4322 if (has_non_young_time) { 4323 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4324 } 4325 } 4326 }; 4327 4328 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4329 _eden.clear(); 4330 4331 double free_cset_start_time = os::elapsedTime(); 4332 4333 { 4334 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4335 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4336 4337 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4338 4339 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4340 cl.name(), 4341 num_workers, 4342 _collection_set.region_length()); 4343 workers()->run_task(&cl, num_workers); 4344 } 4345 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4346 4347 collection_set->clear(); 4348 } 4349 4350 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4351 private: 4352 FreeRegionList* _free_region_list; 4353 HeapRegionSet* _proxy_set; 4354 uint _humongous_objects_reclaimed; 4355 uint _humongous_regions_reclaimed; 4356 size_t _freed_bytes; 4357 public: 4358 4359 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4360 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4361 } 4362 4363 virtual bool do_heap_region(HeapRegion* r) { 4364 if (!r->is_starts_humongous()) { 4365 return false; 4366 } 4367 4368 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4369 4370 oop obj = (oop)r->bottom(); 4371 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4372 4373 // The following checks whether the humongous object is live are sufficient. 4374 // The main additional check (in addition to having a reference from the roots 4375 // or the young gen) is whether the humongous object has a remembered set entry. 4376 // 4377 // A humongous object cannot be live if there is no remembered set for it 4378 // because: 4379 // - there can be no references from within humongous starts regions referencing 4380 // the object because we never allocate other objects into them. 4381 // (I.e. there are no intra-region references that may be missed by the 4382 // remembered set) 4383 // - as soon there is a remembered set entry to the humongous starts region 4384 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4385 // until the end of a concurrent mark. 4386 // 4387 // It is not required to check whether the object has been found dead by marking 4388 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4389 // all objects allocated during that time are considered live. 4390 // SATB marking is even more conservative than the remembered set. 4391 // So if at this point in the collection there is no remembered set entry, 4392 // nobody has a reference to it. 4393 // At the start of collection we flush all refinement logs, and remembered sets 4394 // are completely up-to-date wrt to references to the humongous object. 4395 // 4396 // Other implementation considerations: 4397 // - never consider object arrays at this time because they would pose 4398 // considerable effort for cleaning up the the remembered sets. This is 4399 // required because stale remembered sets might reference locations that 4400 // are currently allocated into. 4401 uint region_idx = r->hrm_index(); 4402 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4403 !r->rem_set()->is_empty()) { 4404 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", 4405 region_idx, 4406 (size_t)obj->size() * HeapWordSize, 4407 p2i(r->bottom()), 4408 r->rem_set()->occupied(), 4409 r->rem_set()->strong_code_roots_list_length(), 4410 next_bitmap->is_marked(r->bottom()), 4411 g1h->is_humongous_reclaim_candidate(region_idx), 4412 obj->is_typeArray() 4413 ); 4414 return false; 4415 } 4416 4417 guarantee(obj->is_typeArray(), 4418 "Only eagerly reclaiming type arrays is supported, but the object " 4419 PTR_FORMAT " is not.", p2i(r->bottom())); 4420 4421 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", 4422 region_idx, 4423 (size_t)obj->size() * HeapWordSize, 4424 p2i(r->bottom()), 4425 r->rem_set()->occupied(), 4426 r->rem_set()->strong_code_roots_list_length(), 4427 next_bitmap->is_marked(r->bottom()), 4428 g1h->is_humongous_reclaim_candidate(region_idx), 4429 obj->is_typeArray() 4430 ); 4431 4432 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4433 cm->humongous_object_eagerly_reclaimed(r); 4434 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4435 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4436 region_idx, 4437 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4438 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4439 _humongous_objects_reclaimed++; 4440 do { 4441 HeapRegion* next = g1h->next_region_in_humongous(r); 4442 _freed_bytes += r->used(); 4443 r->set_containing_set(NULL); 4444 _humongous_regions_reclaimed++; 4445 g1h->free_humongous_region(r, _free_region_list); 4446 r = next; 4447 } while (r != NULL); 4448 4449 return false; 4450 } 4451 4452 uint humongous_objects_reclaimed() { 4453 return _humongous_objects_reclaimed; 4454 } 4455 4456 uint humongous_regions_reclaimed() { 4457 return _humongous_regions_reclaimed; 4458 } 4459 4460 size_t bytes_freed() const { 4461 return _freed_bytes; 4462 } 4463 }; 4464 4465 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4466 assert_at_safepoint_on_vm_thread(); 4467 4468 if (!G1EagerReclaimHumongousObjects || 4469 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4470 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4471 return; 4472 } 4473 4474 double start_time = os::elapsedTime(); 4475 4476 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4477 4478 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4479 heap_region_iterate(&cl); 4480 4481 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4482 4483 G1HRPrinter* hrp = hr_printer(); 4484 if (hrp->is_active()) { 4485 FreeRegionListIterator iter(&local_cleanup_list); 4486 while (iter.more_available()) { 4487 HeapRegion* hr = iter.get_next(); 4488 hrp->cleanup(hr); 4489 } 4490 } 4491 4492 prepend_to_freelist(&local_cleanup_list); 4493 decrement_summary_bytes(cl.bytes_freed()); 4494 4495 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4496 cl.humongous_objects_reclaimed()); 4497 } 4498 4499 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4500 public: 4501 virtual bool do_heap_region(HeapRegion* r) { 4502 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4503 G1CollectedHeap::heap()->clear_in_cset(r); 4504 r->set_young_index_in_cset(-1); 4505 return false; 4506 } 4507 }; 4508 4509 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4510 G1AbandonCollectionSetClosure cl; 4511 collection_set->iterate(&cl); 4512 4513 collection_set->clear(); 4514 collection_set->stop_incremental_building(); 4515 } 4516 4517 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4518 return _allocator->is_retained_old_region(hr); 4519 } 4520 4521 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4522 _eden.add(hr); 4523 _g1_policy->set_region_eden(hr); 4524 } 4525 4526 #ifdef ASSERT 4527 4528 class NoYoungRegionsClosure: public HeapRegionClosure { 4529 private: 4530 bool _success; 4531 public: 4532 NoYoungRegionsClosure() : _success(true) { } 4533 bool do_heap_region(HeapRegion* r) { 4534 if (r->is_young()) { 4535 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4536 p2i(r->bottom()), p2i(r->end())); 4537 _success = false; 4538 } 4539 return false; 4540 } 4541 bool success() { return _success; } 4542 }; 4543 4544 bool G1CollectedHeap::check_young_list_empty() { 4545 bool ret = (young_regions_count() == 0); 4546 4547 NoYoungRegionsClosure closure; 4548 heap_region_iterate(&closure); 4549 ret = ret && closure.success(); 4550 4551 return ret; 4552 } 4553 4554 #endif // ASSERT 4555 4556 class TearDownRegionSetsClosure : public HeapRegionClosure { 4557 HeapRegionSet *_old_set; 4558 4559 public: 4560 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4561 4562 bool do_heap_region(HeapRegion* r) { 4563 if (r->is_old()) { 4564 _old_set->remove(r); 4565 } else if(r->is_young()) { 4566 r->uninstall_surv_rate_group(); 4567 } else { 4568 // We ignore free regions, we'll empty the free list afterwards. 4569 // We ignore humongous and archive regions, we're not tearing down these 4570 // sets. 4571 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4572 "it cannot be another type"); 4573 } 4574 return false; 4575 } 4576 4577 ~TearDownRegionSetsClosure() { 4578 assert(_old_set->is_empty(), "post-condition"); 4579 } 4580 }; 4581 4582 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4583 assert_at_safepoint_on_vm_thread(); 4584 4585 if (!free_list_only) { 4586 TearDownRegionSetsClosure cl(&_old_set); 4587 heap_region_iterate(&cl); 4588 4589 // Note that emptying the _young_list is postponed and instead done as 4590 // the first step when rebuilding the regions sets again. The reason for 4591 // this is that during a full GC string deduplication needs to know if 4592 // a collected region was young or old when the full GC was initiated. 4593 } 4594 _hrm->remove_all_free_regions(); 4595 } 4596 4597 void G1CollectedHeap::increase_used(size_t bytes) { 4598 _summary_bytes_used += bytes; 4599 } 4600 4601 void G1CollectedHeap::decrease_used(size_t bytes) { 4602 assert(_summary_bytes_used >= bytes, 4603 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4604 _summary_bytes_used, bytes); 4605 _summary_bytes_used -= bytes; 4606 } 4607 4608 void G1CollectedHeap::set_used(size_t bytes) { 4609 _summary_bytes_used = bytes; 4610 } 4611 4612 class RebuildRegionSetsClosure : public HeapRegionClosure { 4613 private: 4614 bool _free_list_only; 4615 4616 HeapRegionSet* _old_set; 4617 HeapRegionManager* _hrm; 4618 4619 size_t _total_used; 4620 4621 public: 4622 RebuildRegionSetsClosure(bool free_list_only, 4623 HeapRegionSet* old_set, 4624 HeapRegionManager* hrm) : 4625 _free_list_only(free_list_only), 4626 _old_set(old_set), _hrm(hrm), _total_used(0) { 4627 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4628 if (!free_list_only) { 4629 assert(_old_set->is_empty(), "pre-condition"); 4630 } 4631 } 4632 4633 bool do_heap_region(HeapRegion* r) { 4634 if (r->is_empty()) { 4635 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4636 // Add free regions to the free list 4637 r->set_free(); 4638 _hrm->insert_into_free_list(r); 4639 } else if (!_free_list_only) { 4640 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4641 4642 if (r->is_archive() || r->is_humongous()) { 4643 // We ignore archive and humongous regions. We left these sets unchanged. 4644 } else { 4645 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4646 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4647 r->move_to_old(); 4648 _old_set->add(r); 4649 } 4650 _total_used += r->used(); 4651 } 4652 4653 return false; 4654 } 4655 4656 size_t total_used() { 4657 return _total_used; 4658 } 4659 }; 4660 4661 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4662 assert_at_safepoint_on_vm_thread(); 4663 4664 if (!free_list_only) { 4665 _eden.clear(); 4666 _survivor.clear(); 4667 } 4668 4669 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4670 heap_region_iterate(&cl); 4671 4672 if (!free_list_only) { 4673 set_used(cl.total_used()); 4674 if (_archive_allocator != NULL) { 4675 _archive_allocator->clear_used(); 4676 } 4677 } 4678 assert(used() == recalculate_used(), 4679 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4680 used(), recalculate_used()); 4681 } 4682 4683 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4684 HeapRegion* hr = heap_region_containing(p); 4685 return hr->is_in(p); 4686 } 4687 4688 // Methods for the mutator alloc region 4689 4690 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4691 bool force) { 4692 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4693 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4694 if (force || should_allocate) { 4695 HeapRegion* new_alloc_region = new_region(word_size, 4696 HeapRegionType::Eden, 4697 false /* do_expand */); 4698 if (new_alloc_region != NULL) { 4699 set_region_short_lived_locked(new_alloc_region); 4700 _hr_printer.alloc(new_alloc_region, !should_allocate); 4701 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4702 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4703 return new_alloc_region; 4704 } 4705 } 4706 return NULL; 4707 } 4708 4709 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4710 size_t allocated_bytes) { 4711 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4712 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4713 4714 collection_set()->add_eden_region(alloc_region); 4715 increase_used(allocated_bytes); 4716 _hr_printer.retire(alloc_region); 4717 // We update the eden sizes here, when the region is retired, 4718 // instead of when it's allocated, since this is the point that its 4719 // used space has been recorded in _summary_bytes_used. 4720 g1mm()->update_eden_size(); 4721 } 4722 4723 // Methods for the GC alloc regions 4724 4725 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4726 if (dest.is_old()) { 4727 return true; 4728 } else { 4729 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4730 } 4731 } 4732 4733 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4734 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4735 4736 if (!has_more_regions(dest)) { 4737 return NULL; 4738 } 4739 4740 HeapRegionType type; 4741 if (dest.is_young()) { 4742 type = HeapRegionType::Survivor; 4743 } else { 4744 type = HeapRegionType::Old; 4745 } 4746 4747 HeapRegion* new_alloc_region = new_region(word_size, 4748 type, 4749 true /* do_expand */); 4750 4751 if (new_alloc_region != NULL) { 4752 if (type.is_survivor()) { 4753 new_alloc_region->set_survivor(); 4754 _survivor.add(new_alloc_region); 4755 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4756 } else { 4757 new_alloc_region->set_old(); 4758 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4759 } 4760 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4761 _hr_printer.alloc(new_alloc_region); 4762 return new_alloc_region; 4763 } 4764 return NULL; 4765 } 4766 4767 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4768 size_t allocated_bytes, 4769 InCSetState dest) { 4770 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4771 if (dest.is_old()) { 4772 old_set_add(alloc_region); 4773 } 4774 4775 bool const during_im = collector_state()->in_initial_mark_gc(); 4776 if (during_im && allocated_bytes > 0) { 4777 _cm->root_regions()->add(alloc_region); 4778 } 4779 _hr_printer.retire(alloc_region); 4780 } 4781 4782 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4783 bool expanded = false; 4784 uint index = _hrm->find_highest_free(&expanded); 4785 4786 if (index != G1_NO_HRM_INDEX) { 4787 if (expanded) { 4788 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4789 HeapRegion::GrainWords * HeapWordSize); 4790 } 4791 _hrm->allocate_free_regions_starting_at(index, 1); 4792 return region_at(index); 4793 } 4794 return NULL; 4795 } 4796 4797 // Optimized nmethod scanning 4798 4799 class RegisterNMethodOopClosure: public OopClosure { 4800 G1CollectedHeap* _g1h; 4801 nmethod* _nm; 4802 4803 template <class T> void do_oop_work(T* p) { 4804 T heap_oop = RawAccess<>::oop_load(p); 4805 if (!CompressedOops::is_null(heap_oop)) { 4806 oop obj = CompressedOops::decode_not_null(heap_oop); 4807 HeapRegion* hr = _g1h->heap_region_containing(obj); 4808 assert(!hr->is_continues_humongous(), 4809 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4810 " starting at " HR_FORMAT, 4811 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4812 4813 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4814 hr->add_strong_code_root_locked(_nm); 4815 } 4816 } 4817 4818 public: 4819 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4820 _g1h(g1h), _nm(nm) {} 4821 4822 void do_oop(oop* p) { do_oop_work(p); } 4823 void do_oop(narrowOop* p) { do_oop_work(p); } 4824 }; 4825 4826 class UnregisterNMethodOopClosure: public OopClosure { 4827 G1CollectedHeap* _g1h; 4828 nmethod* _nm; 4829 4830 template <class T> void do_oop_work(T* p) { 4831 T heap_oop = RawAccess<>::oop_load(p); 4832 if (!CompressedOops::is_null(heap_oop)) { 4833 oop obj = CompressedOops::decode_not_null(heap_oop); 4834 HeapRegion* hr = _g1h->heap_region_containing(obj); 4835 assert(!hr->is_continues_humongous(), 4836 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4837 " starting at " HR_FORMAT, 4838 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4839 4840 hr->remove_strong_code_root(_nm); 4841 } 4842 } 4843 4844 public: 4845 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4846 _g1h(g1h), _nm(nm) {} 4847 4848 void do_oop(oop* p) { do_oop_work(p); } 4849 void do_oop(narrowOop* p) { do_oop_work(p); } 4850 }; 4851 4852 // Returns true if the reference points to an object that 4853 // can move in an incremental collection. 4854 bool G1CollectedHeap::is_scavengable(oop obj) { 4855 HeapRegion* hr = heap_region_containing(obj); 4856 return !hr->is_pinned(); 4857 } 4858 4859 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4860 guarantee(nm != NULL, "sanity"); 4861 RegisterNMethodOopClosure reg_cl(this, nm); 4862 nm->oops_do(®_cl); 4863 } 4864 4865 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4866 guarantee(nm != NULL, "sanity"); 4867 UnregisterNMethodOopClosure reg_cl(this, nm); 4868 nm->oops_do(®_cl, true); 4869 } 4870 4871 void G1CollectedHeap::purge_code_root_memory() { 4872 double purge_start = os::elapsedTime(); 4873 G1CodeRootSet::purge(); 4874 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4875 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4876 } 4877 4878 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4879 G1CollectedHeap* _g1h; 4880 4881 public: 4882 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4883 _g1h(g1h) {} 4884 4885 void do_code_blob(CodeBlob* cb) { 4886 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4887 if (nm == NULL) { 4888 return; 4889 } 4890 4891 if (ScavengeRootsInCode) { 4892 _g1h->register_nmethod(nm); 4893 } 4894 } 4895 }; 4896 4897 void G1CollectedHeap::rebuild_strong_code_roots() { 4898 RebuildStrongCodeRootClosure blob_cl(this); 4899 CodeCache::blobs_do(&blob_cl); 4900 } 4901 4902 void G1CollectedHeap::initialize_serviceability() { 4903 _g1mm->initialize_serviceability(); 4904 } 4905 4906 MemoryUsage G1CollectedHeap::memory_usage() { 4907 return _g1mm->memory_usage(); 4908 } 4909 4910 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4911 return _g1mm->memory_managers(); 4912 } 4913 4914 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4915 return _g1mm->memory_pools(); 4916 }