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/g1DirtyCardQueue.hpp" 41 #include "gc/g1/g1EvacStats.inline.hpp" 42 #include "gc/g1/g1FullCollector.hpp" 43 #include "gc/g1/g1GCPhaseTimes.hpp" 44 #include "gc/g1/g1HeapSizingPolicy.hpp" 45 #include "gc/g1/g1HeapTransition.hpp" 46 #include "gc/g1/g1HeapVerifier.hpp" 47 #include "gc/g1/g1HotCardCache.hpp" 48 #include "gc/g1/g1MemoryPool.hpp" 49 #include "gc/g1/g1OopClosures.inline.hpp" 50 #include "gc/g1/g1ParScanThreadState.inline.hpp" 51 #include "gc/g1/g1Policy.hpp" 52 #include "gc/g1/g1RegionToSpaceMapper.hpp" 53 #include "gc/g1/g1RemSet.hpp" 54 #include "gc/g1/g1RootClosures.hpp" 55 #include "gc/g1/g1RootProcessor.hpp" 56 #include "gc/g1/g1SATBMarkQueueSet.hpp" 57 #include "gc/g1/g1StringDedup.hpp" 58 #include "gc/g1/g1ThreadLocalData.hpp" 59 #include "gc/g1/g1YCTypes.hpp" 60 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 61 #include "gc/g1/g1VMOperations.hpp" 62 #include "gc/g1/heapRegion.inline.hpp" 63 #include "gc/g1/heapRegionRemSet.hpp" 64 #include "gc/g1/heapRegionSet.inline.hpp" 65 #include "gc/shared/gcBehaviours.hpp" 66 #include "gc/shared/gcHeapSummary.hpp" 67 #include "gc/shared/gcId.hpp" 68 #include "gc/shared/gcLocker.hpp" 69 #include "gc/shared/gcTimer.hpp" 70 #include "gc/shared/gcTrace.hpp" 71 #include "gc/shared/gcTraceTime.inline.hpp" 72 #include "gc/shared/generationSpec.hpp" 73 #include "gc/shared/isGCActiveMark.hpp" 74 #include "gc/shared/oopStorageParState.hpp" 75 #include "gc/shared/parallelCleaning.hpp" 76 #include "gc/shared/preservedMarks.inline.hpp" 77 #include "gc/shared/suspendibleThreadSet.hpp" 78 #include "gc/shared/referenceProcessor.inline.hpp" 79 #include "gc/shared/taskqueue.inline.hpp" 80 #include "gc/shared/weakProcessor.inline.hpp" 81 #include "gc/shared/workerPolicy.hpp" 82 #if INCLUDE_JVMCI 83 #include "jvmci/jvmci.hpp" 84 #endif 85 #include "logging/log.hpp" 86 #include "memory/allocation.hpp" 87 #include "memory/iterator.hpp" 88 #include "memory/resourceArea.hpp" 89 #include "oops/access.inline.hpp" 90 #include "oops/compressedOops.inline.hpp" 91 #include "oops/oop.inline.hpp" 92 #include "runtime/atomic.hpp" 93 #include "runtime/flags/flagSetting.hpp" 94 #include "runtime/handles.inline.hpp" 95 #include "runtime/init.hpp" 96 #include "runtime/orderAccess.hpp" 97 #include "runtime/threadSMR.hpp" 98 #include "runtime/vmThread.hpp" 99 #include "utilities/align.hpp" 100 #include "utilities/globalDefinitions.hpp" 101 #include "utilities/stack.inline.hpp" 102 103 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 104 105 // INVARIANTS/NOTES 106 // 107 // All allocation activity covered by the G1CollectedHeap interface is 108 // serialized by acquiring the HeapLock. This happens in mem_allocate 109 // and allocate_new_tlab, which are the "entry" points to the 110 // allocation code from the rest of the JVM. (Note that this does not 111 // apply to TLAB allocation, which is not part of this interface: it 112 // is done by clients of this interface.) 113 114 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 115 private: 116 size_t _num_dirtied; 117 G1CollectedHeap* _g1h; 118 G1CardTable* _g1_ct; 119 120 HeapRegion* region_for_card(CardValue* card_ptr) const { 121 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 122 } 123 124 bool will_become_free(HeapRegion* hr) const { 125 // A region will be freed by free_collection_set if the region is in the 126 // collection set and has not had an evacuation failure. 127 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 128 } 129 130 public: 131 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 132 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 133 134 bool do_card_ptr(CardValue* card_ptr, uint worker_i) { 135 HeapRegion* hr = region_for_card(card_ptr); 136 137 // Should only dirty cards in regions that won't be freed. 138 if (!will_become_free(hr)) { 139 *card_ptr = G1CardTable::dirty_card_val(); 140 _num_dirtied++; 141 } 142 143 return true; 144 } 145 146 size_t num_dirtied() const { return _num_dirtied; } 147 }; 148 149 150 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 151 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 152 } 153 154 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 155 // The from card cache is not the memory that is actually committed. So we cannot 156 // take advantage of the zero_filled parameter. 157 reset_from_card_cache(start_idx, num_regions); 158 } 159 160 161 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 162 MemRegion mr) { 163 return new HeapRegion(hrs_index, bot(), mr); 164 } 165 166 // Private methods. 167 168 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) { 169 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 170 "the only time we use this to allocate a humongous region is " 171 "when we are allocating a single humongous region"); 172 173 HeapRegion* res = _hrm->allocate_free_region(type); 174 175 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 176 // Currently, only attempts to allocate GC alloc regions set 177 // do_expand to true. So, we should only reach here during a 178 // safepoint. If this assumption changes we might have to 179 // reconsider the use of _expand_heap_after_alloc_failure. 180 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 181 182 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 183 word_size * HeapWordSize); 184 185 if (expand(word_size * HeapWordSize)) { 186 // Given that expand() succeeded in expanding the heap, and we 187 // always expand the heap by an amount aligned to the heap 188 // region size, the free list should in theory not be empty. 189 // In either case allocate_free_region() will check for NULL. 190 res = _hrm->allocate_free_region(type); 191 } else { 192 _expand_heap_after_alloc_failure = false; 193 } 194 } 195 return res; 196 } 197 198 HeapWord* 199 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 200 uint num_regions, 201 size_t word_size) { 202 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 203 assert(is_humongous(word_size), "word_size should be humongous"); 204 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 205 206 // Index of last region in the series. 207 uint last = first + num_regions - 1; 208 209 // We need to initialize the region(s) we just discovered. This is 210 // a bit tricky given that it can happen concurrently with 211 // refinement threads refining cards on these regions and 212 // potentially wanting to refine the BOT as they are scanning 213 // those cards (this can happen shortly after a cleanup; see CR 214 // 6991377). So we have to set up the region(s) carefully and in 215 // a specific order. 216 217 // The word size sum of all the regions we will allocate. 218 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 219 assert(word_size <= word_size_sum, "sanity"); 220 221 // This will be the "starts humongous" region. 222 HeapRegion* first_hr = region_at(first); 223 // The header of the new object will be placed at the bottom of 224 // the first region. 225 HeapWord* new_obj = first_hr->bottom(); 226 // This will be the new top of the new object. 227 HeapWord* obj_top = new_obj + word_size; 228 229 // First, we need to zero the header of the space that we will be 230 // allocating. When we update top further down, some refinement 231 // threads might try to scan the region. By zeroing the header we 232 // ensure that any thread that will try to scan the region will 233 // come across the zero klass word and bail out. 234 // 235 // NOTE: It would not have been correct to have used 236 // CollectedHeap::fill_with_object() and make the space look like 237 // an int array. The thread that is doing the allocation will 238 // later update the object header to a potentially different array 239 // type and, for a very short period of time, the klass and length 240 // fields will be inconsistent. This could cause a refinement 241 // thread to calculate the object size incorrectly. 242 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 243 244 // Next, pad out the unused tail of the last region with filler 245 // objects, for improved usage accounting. 246 // How many words we use for filler objects. 247 size_t word_fill_size = word_size_sum - word_size; 248 249 // How many words memory we "waste" which cannot hold a filler object. 250 size_t words_not_fillable = 0; 251 252 if (word_fill_size >= min_fill_size()) { 253 fill_with_objects(obj_top, word_fill_size); 254 } else if (word_fill_size > 0) { 255 // We have space to fill, but we cannot fit an object there. 256 words_not_fillable = word_fill_size; 257 word_fill_size = 0; 258 } 259 260 // We will set up the first region as "starts humongous". This 261 // will also update the BOT covering all the regions to reflect 262 // that there is a single object that starts at the bottom of the 263 // first region. 264 first_hr->set_starts_humongous(obj_top, word_fill_size); 265 _policy->remset_tracker()->update_at_allocate(first_hr); 266 // Then, if there are any, we will set up the "continues 267 // humongous" regions. 268 HeapRegion* hr = NULL; 269 for (uint i = first + 1; i <= last; ++i) { 270 hr = region_at(i); 271 hr->set_continues_humongous(first_hr); 272 _policy->remset_tracker()->update_at_allocate(hr); 273 } 274 275 // Up to this point no concurrent thread would have been able to 276 // do any scanning on any region in this series. All the top 277 // fields still point to bottom, so the intersection between 278 // [bottom,top] and [card_start,card_end] will be empty. Before we 279 // update the top fields, we'll do a storestore to make sure that 280 // no thread sees the update to top before the zeroing of the 281 // object header and the BOT initialization. 282 OrderAccess::storestore(); 283 284 // Now, we will update the top fields of the "continues humongous" 285 // regions except the last one. 286 for (uint i = first; i < last; ++i) { 287 hr = region_at(i); 288 hr->set_top(hr->end()); 289 } 290 291 hr = region_at(last); 292 // If we cannot fit a filler object, we must set top to the end 293 // of the humongous object, otherwise we cannot iterate the heap 294 // and the BOT will not be complete. 295 hr->set_top(hr->end() - words_not_fillable); 296 297 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 298 "obj_top should be in last region"); 299 300 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 301 302 assert(words_not_fillable == 0 || 303 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 304 "Miscalculation in humongous allocation"); 305 306 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 307 308 for (uint i = first; i <= last; ++i) { 309 hr = region_at(i); 310 _humongous_set.add(hr); 311 _hr_printer.alloc(hr); 312 } 313 314 return new_obj; 315 } 316 317 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 318 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 319 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 320 } 321 322 // If could fit into free regions w/o expansion, try. 323 // Otherwise, if can expand, do so. 324 // Otherwise, if using ex regions might help, try with ex given back. 325 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 326 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 327 328 _verifier->verify_region_sets_optional(); 329 330 uint first = G1_NO_HRM_INDEX; 331 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 332 333 if (obj_regions == 1) { 334 // Only one region to allocate, try to use a fast path by directly allocating 335 // from the free lists. Do not try to expand here, we will potentially do that 336 // later. 337 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 338 if (hr != NULL) { 339 first = hr->hrm_index(); 340 } 341 } else { 342 // Policy: Try only empty regions (i.e. already committed first). Maybe we 343 // are lucky enough to find some. 344 first = _hrm->find_contiguous_only_empty(obj_regions); 345 if (first != G1_NO_HRM_INDEX) { 346 _hrm->allocate_free_regions_starting_at(first, obj_regions); 347 } 348 } 349 350 if (first == G1_NO_HRM_INDEX) { 351 // Policy: We could not find enough regions for the humongous object in the 352 // free list. Look through the heap to find a mix of free and uncommitted regions. 353 // If so, try expansion. 354 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 355 if (first != G1_NO_HRM_INDEX) { 356 // We found something. Make sure these regions are committed, i.e. expand 357 // the heap. Alternatively we could do a defragmentation GC. 358 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 359 word_size * HeapWordSize); 360 361 _hrm->expand_at(first, obj_regions, workers()); 362 policy()->record_new_heap_size(num_regions()); 363 364 #ifdef ASSERT 365 for (uint i = first; i < first + obj_regions; ++i) { 366 HeapRegion* hr = region_at(i); 367 assert(hr->is_free(), "sanity"); 368 assert(hr->is_empty(), "sanity"); 369 assert(is_on_master_free_list(hr), "sanity"); 370 } 371 #endif 372 _hrm->allocate_free_regions_starting_at(first, obj_regions); 373 } else { 374 // Policy: Potentially trigger a defragmentation GC. 375 } 376 } 377 378 HeapWord* result = NULL; 379 if (first != G1_NO_HRM_INDEX) { 380 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 381 assert(result != NULL, "it should always return a valid result"); 382 383 // A successful humongous object allocation changes the used space 384 // information of the old generation so we need to recalculate the 385 // sizes and update the jstat counters here. 386 g1mm()->update_sizes(); 387 } 388 389 _verifier->verify_region_sets_optional(); 390 391 return result; 392 } 393 394 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 395 size_t requested_size, 396 size_t* actual_size) { 397 assert_heap_not_locked_and_not_at_safepoint(); 398 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 399 400 return attempt_allocation(min_size, requested_size, actual_size); 401 } 402 403 HeapWord* 404 G1CollectedHeap::mem_allocate(size_t word_size, 405 bool* gc_overhead_limit_was_exceeded) { 406 assert_heap_not_locked_and_not_at_safepoint(); 407 408 if (is_humongous(word_size)) { 409 return attempt_allocation_humongous(word_size); 410 } 411 size_t dummy = 0; 412 return attempt_allocation(word_size, word_size, &dummy); 413 } 414 415 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 416 ResourceMark rm; // For retrieving the thread names in log messages. 417 418 // Make sure you read the note in attempt_allocation_humongous(). 419 420 assert_heap_not_locked_and_not_at_safepoint(); 421 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 422 "be called for humongous allocation requests"); 423 424 // We should only get here after the first-level allocation attempt 425 // (attempt_allocation()) failed to allocate. 426 427 // We will loop until a) we manage to successfully perform the 428 // allocation or b) we successfully schedule a collection which 429 // fails to perform the allocation. b) is the only case when we'll 430 // return NULL. 431 HeapWord* result = NULL; 432 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 433 bool should_try_gc; 434 uint gc_count_before; 435 436 { 437 MutexLockerEx x(Heap_lock); 438 result = _allocator->attempt_allocation_locked(word_size); 439 if (result != NULL) { 440 return result; 441 } 442 443 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 444 // This is different to when only GCLocker::needs_gc() is set: try to avoid 445 // waiting because the GCLocker is active to not wait too long. 446 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 447 // No need for an ergo message here, can_expand_young_list() does this when 448 // it returns true. 449 result = _allocator->attempt_allocation_force(word_size); 450 if (result != NULL) { 451 return result; 452 } 453 } 454 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 455 // the GCLocker initiated GC has been performed and then retry. This includes 456 // the case when the GC Locker is not active but has not been performed. 457 should_try_gc = !GCLocker::needs_gc(); 458 // Read the GC count while still holding the Heap_lock. 459 gc_count_before = total_collections(); 460 } 461 462 if (should_try_gc) { 463 bool succeeded; 464 result = do_collection_pause(word_size, gc_count_before, &succeeded, 465 GCCause::_g1_inc_collection_pause); 466 if (result != NULL) { 467 assert(succeeded, "only way to get back a non-NULL result"); 468 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 469 Thread::current()->name(), p2i(result)); 470 return result; 471 } 472 473 if (succeeded) { 474 // We successfully scheduled a collection which failed to allocate. No 475 // point in trying to allocate further. We'll just return NULL. 476 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 477 SIZE_FORMAT " words", Thread::current()->name(), word_size); 478 return NULL; 479 } 480 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 481 Thread::current()->name(), word_size); 482 } else { 483 // Failed to schedule a collection. 484 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 485 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 486 SIZE_FORMAT " words", Thread::current()->name(), word_size); 487 return NULL; 488 } 489 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 490 // The GCLocker is either active or the GCLocker initiated 491 // GC has not yet been performed. Stall until it is and 492 // then retry the allocation. 493 GCLocker::stall_until_clear(); 494 gclocker_retry_count += 1; 495 } 496 497 // We can reach here if we were unsuccessful in scheduling a 498 // collection (because another thread beat us to it) or if we were 499 // stalled due to the GC locker. In either can we should retry the 500 // allocation attempt in case another thread successfully 501 // performed a collection and reclaimed enough space. We do the 502 // first attempt (without holding the Heap_lock) here and the 503 // follow-on attempt will be at the start of the next loop 504 // iteration (after taking the Heap_lock). 505 size_t dummy = 0; 506 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 507 if (result != NULL) { 508 return result; 509 } 510 511 // Give a warning if we seem to be looping forever. 512 if ((QueuedAllocationWarningCount > 0) && 513 (try_count % QueuedAllocationWarningCount == 0)) { 514 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 515 Thread::current()->name(), try_count, word_size); 516 } 517 } 518 519 ShouldNotReachHere(); 520 return NULL; 521 } 522 523 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 524 assert_at_safepoint_on_vm_thread(); 525 if (_archive_allocator == NULL) { 526 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 527 } 528 } 529 530 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 531 // Allocations in archive regions cannot be of a size that would be considered 532 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 533 // may be different at archive-restore time. 534 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 535 } 536 537 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 538 assert_at_safepoint_on_vm_thread(); 539 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 540 if (is_archive_alloc_too_large(word_size)) { 541 return NULL; 542 } 543 return _archive_allocator->archive_mem_allocate(word_size); 544 } 545 546 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 547 size_t end_alignment_in_bytes) { 548 assert_at_safepoint_on_vm_thread(); 549 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 550 551 // Call complete_archive to do the real work, filling in the MemRegion 552 // array with the archive regions. 553 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 554 delete _archive_allocator; 555 _archive_allocator = NULL; 556 } 557 558 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 559 assert(ranges != NULL, "MemRegion array NULL"); 560 assert(count != 0, "No MemRegions provided"); 561 MemRegion reserved = _hrm->reserved(); 562 for (size_t i = 0; i < count; i++) { 563 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 564 return false; 565 } 566 } 567 return true; 568 } 569 570 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 571 size_t count, 572 bool open) { 573 assert(!is_init_completed(), "Expect to be called at JVM init time"); 574 assert(ranges != NULL, "MemRegion array NULL"); 575 assert(count != 0, "No MemRegions provided"); 576 MutexLockerEx x(Heap_lock); 577 578 MemRegion reserved = _hrm->reserved(); 579 HeapWord* prev_last_addr = NULL; 580 HeapRegion* prev_last_region = NULL; 581 582 // Temporarily disable pretouching of heap pages. This interface is used 583 // when mmap'ing archived heap data in, so pre-touching is wasted. 584 FlagSetting fs(AlwaysPreTouch, false); 585 586 // Enable archive object checking used by G1MarkSweep. We have to let it know 587 // about each archive range, so that objects in those ranges aren't marked. 588 G1ArchiveAllocator::enable_archive_object_check(); 589 590 // For each specified MemRegion range, allocate the corresponding G1 591 // regions and mark them as archive regions. We expect the ranges 592 // in ascending starting address order, without overlap. 593 for (size_t i = 0; i < count; i++) { 594 MemRegion curr_range = ranges[i]; 595 HeapWord* start_address = curr_range.start(); 596 size_t word_size = curr_range.word_size(); 597 HeapWord* last_address = curr_range.last(); 598 size_t commits = 0; 599 600 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 601 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 602 p2i(start_address), p2i(last_address)); 603 guarantee(start_address > prev_last_addr, 604 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 605 p2i(start_address), p2i(prev_last_addr)); 606 prev_last_addr = last_address; 607 608 // Check for ranges that start in the same G1 region in which the previous 609 // range ended, and adjust the start address so we don't try to allocate 610 // the same region again. If the current range is entirely within that 611 // region, skip it, just adjusting the recorded top. 612 HeapRegion* start_region = _hrm->addr_to_region(start_address); 613 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 614 start_address = start_region->end(); 615 if (start_address > last_address) { 616 increase_used(word_size * HeapWordSize); 617 start_region->set_top(last_address + 1); 618 continue; 619 } 620 start_region->set_top(start_address); 621 curr_range = MemRegion(start_address, last_address + 1); 622 start_region = _hrm->addr_to_region(start_address); 623 } 624 625 // Perform the actual region allocation, exiting if it fails. 626 // Then note how much new space we have allocated. 627 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 628 return false; 629 } 630 increase_used(word_size * HeapWordSize); 631 if (commits != 0) { 632 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 633 HeapRegion::GrainWords * HeapWordSize * commits); 634 635 } 636 637 // Mark each G1 region touched by the range as archive, add it to 638 // the old set, and set top. 639 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 640 HeapRegion* last_region = _hrm->addr_to_region(last_address); 641 prev_last_region = last_region; 642 643 while (curr_region != NULL) { 644 assert(curr_region->is_empty() && !curr_region->is_pinned(), 645 "Region already in use (index %u)", curr_region->hrm_index()); 646 if (open) { 647 curr_region->set_open_archive(); 648 } else { 649 curr_region->set_closed_archive(); 650 } 651 _hr_printer.alloc(curr_region); 652 _archive_set.add(curr_region); 653 HeapWord* top; 654 HeapRegion* next_region; 655 if (curr_region != last_region) { 656 top = curr_region->end(); 657 next_region = _hrm->next_region_in_heap(curr_region); 658 } else { 659 top = last_address + 1; 660 next_region = NULL; 661 } 662 curr_region->set_top(top); 663 curr_region->set_first_dead(top); 664 curr_region->set_end_of_live(top); 665 curr_region = next_region; 666 } 667 668 // Notify mark-sweep of the archive 669 G1ArchiveAllocator::set_range_archive(curr_range, open); 670 } 671 return true; 672 } 673 674 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 675 assert(!is_init_completed(), "Expect to be called at JVM init time"); 676 assert(ranges != NULL, "MemRegion array NULL"); 677 assert(count != 0, "No MemRegions provided"); 678 MemRegion reserved = _hrm->reserved(); 679 HeapWord *prev_last_addr = NULL; 680 HeapRegion* prev_last_region = NULL; 681 682 // For each MemRegion, create filler objects, if needed, in the G1 regions 683 // that contain the address range. The address range actually within the 684 // MemRegion will not be modified. That is assumed to have been initialized 685 // elsewhere, probably via an mmap of archived heap data. 686 MutexLockerEx x(Heap_lock); 687 for (size_t i = 0; i < count; i++) { 688 HeapWord* start_address = ranges[i].start(); 689 HeapWord* last_address = ranges[i].last(); 690 691 assert(reserved.contains(start_address) && reserved.contains(last_address), 692 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 693 p2i(start_address), p2i(last_address)); 694 assert(start_address > prev_last_addr, 695 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 696 p2i(start_address), p2i(prev_last_addr)); 697 698 HeapRegion* start_region = _hrm->addr_to_region(start_address); 699 HeapRegion* last_region = _hrm->addr_to_region(last_address); 700 HeapWord* bottom_address = start_region->bottom(); 701 702 // Check for a range beginning in the same region in which the 703 // previous one ended. 704 if (start_region == prev_last_region) { 705 bottom_address = prev_last_addr + 1; 706 } 707 708 // Verify that the regions were all marked as archive regions by 709 // alloc_archive_regions. 710 HeapRegion* curr_region = start_region; 711 while (curr_region != NULL) { 712 guarantee(curr_region->is_archive(), 713 "Expected archive region at index %u", curr_region->hrm_index()); 714 if (curr_region != last_region) { 715 curr_region = _hrm->next_region_in_heap(curr_region); 716 } else { 717 curr_region = NULL; 718 } 719 } 720 721 prev_last_addr = last_address; 722 prev_last_region = last_region; 723 724 // Fill the memory below the allocated range with dummy object(s), 725 // if the region bottom does not match the range start, or if the previous 726 // range ended within the same G1 region, and there is a gap. 727 if (start_address != bottom_address) { 728 size_t fill_size = pointer_delta(start_address, bottom_address); 729 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 730 increase_used(fill_size * HeapWordSize); 731 } 732 } 733 } 734 735 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 736 size_t desired_word_size, 737 size_t* actual_word_size) { 738 assert_heap_not_locked_and_not_at_safepoint(); 739 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 740 "be called for humongous allocation requests"); 741 742 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 743 744 if (result == NULL) { 745 *actual_word_size = desired_word_size; 746 result = attempt_allocation_slow(desired_word_size); 747 } 748 749 assert_heap_not_locked(); 750 if (result != NULL) { 751 assert(*actual_word_size != 0, "Actual size must have been set here"); 752 dirty_young_block(result, *actual_word_size); 753 } else { 754 *actual_word_size = 0; 755 } 756 757 return result; 758 } 759 760 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 761 assert(!is_init_completed(), "Expect to be called at JVM init time"); 762 assert(ranges != NULL, "MemRegion array NULL"); 763 assert(count != 0, "No MemRegions provided"); 764 MemRegion reserved = _hrm->reserved(); 765 HeapWord* prev_last_addr = NULL; 766 HeapRegion* prev_last_region = NULL; 767 size_t size_used = 0; 768 size_t uncommitted_regions = 0; 769 770 // For each Memregion, free the G1 regions that constitute it, and 771 // notify mark-sweep that the range is no longer to be considered 'archive.' 772 MutexLockerEx x(Heap_lock); 773 for (size_t i = 0; i < count; i++) { 774 HeapWord* start_address = ranges[i].start(); 775 HeapWord* last_address = ranges[i].last(); 776 777 assert(reserved.contains(start_address) && reserved.contains(last_address), 778 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 779 p2i(start_address), p2i(last_address)); 780 assert(start_address > prev_last_addr, 781 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 782 p2i(start_address), p2i(prev_last_addr)); 783 size_used += ranges[i].byte_size(); 784 prev_last_addr = last_address; 785 786 HeapRegion* start_region = _hrm->addr_to_region(start_address); 787 HeapRegion* last_region = _hrm->addr_to_region(last_address); 788 789 // Check for ranges that start in the same G1 region in which the previous 790 // range ended, and adjust the start address so we don't try to free 791 // the same region again. If the current range is entirely within that 792 // region, skip it. 793 if (start_region == prev_last_region) { 794 start_address = start_region->end(); 795 if (start_address > last_address) { 796 continue; 797 } 798 start_region = _hrm->addr_to_region(start_address); 799 } 800 prev_last_region = last_region; 801 802 // After verifying that each region was marked as an archive region by 803 // alloc_archive_regions, set it free and empty and uncommit it. 804 HeapRegion* curr_region = start_region; 805 while (curr_region != NULL) { 806 guarantee(curr_region->is_archive(), 807 "Expected archive region at index %u", curr_region->hrm_index()); 808 uint curr_index = curr_region->hrm_index(); 809 _archive_set.remove(curr_region); 810 curr_region->set_free(); 811 curr_region->set_top(curr_region->bottom()); 812 if (curr_region != last_region) { 813 curr_region = _hrm->next_region_in_heap(curr_region); 814 } else { 815 curr_region = NULL; 816 } 817 _hrm->shrink_at(curr_index, 1); 818 uncommitted_regions++; 819 } 820 821 // Notify mark-sweep that this is no longer an archive range. 822 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 823 } 824 825 if (uncommitted_regions != 0) { 826 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 827 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 828 } 829 decrease_used(size_used); 830 } 831 832 oop G1CollectedHeap::materialize_archived_object(oop obj) { 833 assert(obj != NULL, "archived obj is NULL"); 834 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 835 836 // Loading an archived object makes it strongly reachable. If it is 837 // loaded during concurrent marking, it must be enqueued to the SATB 838 // queue, shading the previously white object gray. 839 G1BarrierSet::enqueue(obj); 840 841 return obj; 842 } 843 844 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 845 ResourceMark rm; // For retrieving the thread names in log messages. 846 847 // The structure of this method has a lot of similarities to 848 // attempt_allocation_slow(). The reason these two were not merged 849 // into a single one is that such a method would require several "if 850 // allocation is not humongous do this, otherwise do that" 851 // conditional paths which would obscure its flow. In fact, an early 852 // version of this code did use a unified method which was harder to 853 // follow and, as a result, it had subtle bugs that were hard to 854 // track down. So keeping these two methods separate allows each to 855 // be more readable. It will be good to keep these two in sync as 856 // much as possible. 857 858 assert_heap_not_locked_and_not_at_safepoint(); 859 assert(is_humongous(word_size), "attempt_allocation_humongous() " 860 "should only be called for humongous allocations"); 861 862 // Humongous objects can exhaust the heap quickly, so we should check if we 863 // need to start a marking cycle at each humongous object allocation. We do 864 // the check before we do the actual allocation. The reason for doing it 865 // before the allocation is that we avoid having to keep track of the newly 866 // allocated memory while we do a GC. 867 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 868 word_size)) { 869 collect(GCCause::_g1_humongous_allocation); 870 } 871 872 // We will loop until a) we manage to successfully perform the 873 // allocation or b) we successfully schedule a collection which 874 // fails to perform the allocation. b) is the only case when we'll 875 // return NULL. 876 HeapWord* result = NULL; 877 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 878 bool should_try_gc; 879 uint gc_count_before; 880 881 882 { 883 MutexLockerEx x(Heap_lock); 884 885 // Given that humongous objects are not allocated in young 886 // regions, we'll first try to do the allocation without doing a 887 // collection hoping that there's enough space in the heap. 888 result = humongous_obj_allocate(word_size); 889 if (result != NULL) { 890 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 891 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 892 return result; 893 } 894 895 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 896 // the GCLocker initiated GC has been performed and then retry. This includes 897 // the case when the GC Locker is not active but has not been performed. 898 should_try_gc = !GCLocker::needs_gc(); 899 // Read the GC count while still holding the Heap_lock. 900 gc_count_before = total_collections(); 901 } 902 903 if (should_try_gc) { 904 bool succeeded; 905 result = do_collection_pause(word_size, gc_count_before, &succeeded, 906 GCCause::_g1_humongous_allocation); 907 if (result != NULL) { 908 assert(succeeded, "only way to get back a non-NULL result"); 909 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 910 Thread::current()->name(), p2i(result)); 911 return result; 912 } 913 914 if (succeeded) { 915 // We successfully scheduled a collection which failed to allocate. No 916 // point in trying to allocate further. We'll just return NULL. 917 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 918 SIZE_FORMAT " words", Thread::current()->name(), word_size); 919 return NULL; 920 } 921 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 922 Thread::current()->name(), word_size); 923 } else { 924 // Failed to schedule a collection. 925 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 926 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 927 SIZE_FORMAT " words", Thread::current()->name(), word_size); 928 return NULL; 929 } 930 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 931 // The GCLocker is either active or the GCLocker initiated 932 // GC has not yet been performed. Stall until it is and 933 // then retry the allocation. 934 GCLocker::stall_until_clear(); 935 gclocker_retry_count += 1; 936 } 937 938 939 // We can reach here if we were unsuccessful in scheduling a 940 // collection (because another thread beat us to it) or if we were 941 // stalled due to the GC locker. In either can we should retry the 942 // allocation attempt in case another thread successfully 943 // performed a collection and reclaimed enough space. 944 // Humongous object allocation always needs a lock, so we wait for the retry 945 // in the next iteration of the loop, unlike for the regular iteration case. 946 // Give a warning if we seem to be looping forever. 947 948 if ((QueuedAllocationWarningCount > 0) && 949 (try_count % QueuedAllocationWarningCount == 0)) { 950 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 951 Thread::current()->name(), try_count, word_size); 952 } 953 } 954 955 ShouldNotReachHere(); 956 return NULL; 957 } 958 959 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 960 bool expect_null_mutator_alloc_region) { 961 assert_at_safepoint_on_vm_thread(); 962 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 963 "the current alloc region was unexpectedly found to be non-NULL"); 964 965 if (!is_humongous(word_size)) { 966 return _allocator->attempt_allocation_locked(word_size); 967 } else { 968 HeapWord* result = humongous_obj_allocate(word_size); 969 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 970 collector_state()->set_initiate_conc_mark_if_possible(true); 971 } 972 return result; 973 } 974 975 ShouldNotReachHere(); 976 } 977 978 class PostCompactionPrinterClosure: public HeapRegionClosure { 979 private: 980 G1HRPrinter* _hr_printer; 981 public: 982 bool do_heap_region(HeapRegion* hr) { 983 assert(!hr->is_young(), "not expecting to find young regions"); 984 _hr_printer->post_compaction(hr); 985 return false; 986 } 987 988 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 989 : _hr_printer(hr_printer) { } 990 }; 991 992 void G1CollectedHeap::print_hrm_post_compaction() { 993 if (_hr_printer.is_active()) { 994 PostCompactionPrinterClosure cl(hr_printer()); 995 heap_region_iterate(&cl); 996 } 997 } 998 999 void G1CollectedHeap::abort_concurrent_cycle() { 1000 // If we start the compaction before the CM threads finish 1001 // scanning the root regions we might trip them over as we'll 1002 // be moving objects / updating references. So let's wait until 1003 // they are done. By telling them to abort, they should complete 1004 // early. 1005 _cm->root_regions()->abort(); 1006 _cm->root_regions()->wait_until_scan_finished(); 1007 1008 // Disable discovery and empty the discovered lists 1009 // for the CM ref processor. 1010 _ref_processor_cm->disable_discovery(); 1011 _ref_processor_cm->abandon_partial_discovery(); 1012 _ref_processor_cm->verify_no_references_recorded(); 1013 1014 // Abandon current iterations of concurrent marking and concurrent 1015 // refinement, if any are in progress. 1016 concurrent_mark()->concurrent_cycle_abort(); 1017 } 1018 1019 void G1CollectedHeap::prepare_heap_for_full_collection() { 1020 // Make sure we'll choose a new allocation region afterwards. 1021 _allocator->release_mutator_alloc_region(); 1022 _allocator->abandon_gc_alloc_regions(); 1023 1024 // We may have added regions to the current incremental collection 1025 // set between the last GC or pause and now. We need to clear the 1026 // incremental collection set and then start rebuilding it afresh 1027 // after this full GC. 1028 abandon_collection_set(collection_set()); 1029 1030 tear_down_region_sets(false /* free_list_only */); 1031 1032 hrm()->prepare_for_full_collection_start(); 1033 } 1034 1035 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1036 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1037 assert(used() == recalculate_used(), "Should be equal"); 1038 _verifier->verify_region_sets_optional(); 1039 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1040 _verifier->check_bitmaps("Full GC Start"); 1041 } 1042 1043 void G1CollectedHeap::prepare_heap_for_mutators() { 1044 hrm()->prepare_for_full_collection_end(); 1045 1046 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1047 ClassLoaderDataGraph::purge(); 1048 MetaspaceUtils::verify_metrics(); 1049 1050 // Prepare heap for normal collections. 1051 assert(num_free_regions() == 0, "we should not have added any free regions"); 1052 rebuild_region_sets(false /* free_list_only */); 1053 abort_refinement(); 1054 resize_heap_if_necessary(); 1055 1056 // Rebuild the strong code root lists for each region 1057 rebuild_strong_code_roots(); 1058 1059 // Purge code root memory 1060 purge_code_root_memory(); 1061 1062 // Start a new incremental collection set for the next pause 1063 start_new_collection_set(); 1064 1065 _allocator->init_mutator_alloc_region(); 1066 1067 // Post collection state updates. 1068 MetaspaceGC::compute_new_size(); 1069 } 1070 1071 void G1CollectedHeap::abort_refinement() { 1072 if (_hot_card_cache->use_cache()) { 1073 _hot_card_cache->reset_hot_cache(); 1074 } 1075 1076 // Discard all remembered set updates. 1077 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1078 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1079 } 1080 1081 void G1CollectedHeap::verify_after_full_collection() { 1082 _hrm->verify_optional(); 1083 _verifier->verify_region_sets_optional(); 1084 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1085 // Clear the previous marking bitmap, if needed for bitmap verification. 1086 // Note we cannot do this when we clear the next marking bitmap in 1087 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1088 // objects marked during a full GC against the previous bitmap. 1089 // But we need to clear it before calling check_bitmaps below since 1090 // the full GC has compacted objects and updated TAMS but not updated 1091 // the prev bitmap. 1092 if (G1VerifyBitmaps) { 1093 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification"); 1094 _cm->clear_prev_bitmap(workers()); 1095 } 1096 // This call implicitly verifies that the next bitmap is clear after Full GC. 1097 _verifier->check_bitmaps("Full GC End"); 1098 1099 // At this point there should be no regions in the 1100 // entire heap tagged as young. 1101 assert(check_young_list_empty(), "young list should be empty at this point"); 1102 1103 // Note: since we've just done a full GC, concurrent 1104 // marking is no longer active. Therefore we need not 1105 // re-enable reference discovery for the CM ref processor. 1106 // That will be done at the start of the next marking cycle. 1107 // We also know that the STW processor should no longer 1108 // discover any new references. 1109 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1110 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1111 _ref_processor_stw->verify_no_references_recorded(); 1112 _ref_processor_cm->verify_no_references_recorded(); 1113 } 1114 1115 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1116 // Post collection logging. 1117 // We should do this after we potentially resize the heap so 1118 // that all the COMMIT / UNCOMMIT events are generated before 1119 // the compaction events. 1120 print_hrm_post_compaction(); 1121 heap_transition->print(); 1122 print_heap_after_gc(); 1123 print_heap_regions(); 1124 #ifdef TRACESPINNING 1125 ParallelTaskTerminator::print_termination_counts(); 1126 #endif 1127 } 1128 1129 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1130 bool clear_all_soft_refs) { 1131 assert_at_safepoint_on_vm_thread(); 1132 1133 if (GCLocker::check_active_before_gc()) { 1134 // Full GC was not completed. 1135 return false; 1136 } 1137 1138 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1139 soft_ref_policy()->should_clear_all_soft_refs(); 1140 1141 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1142 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1143 1144 collector.prepare_collection(); 1145 collector.collect(); 1146 collector.complete_collection(); 1147 1148 // Full collection was successfully completed. 1149 return true; 1150 } 1151 1152 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1153 // Currently, there is no facility in the do_full_collection(bool) API to notify 1154 // the caller that the collection did not succeed (e.g., because it was locked 1155 // out by the GC locker). So, right now, we'll ignore the return value. 1156 bool dummy = do_full_collection(true, /* explicit_gc */ 1157 clear_all_soft_refs); 1158 } 1159 1160 void G1CollectedHeap::resize_heap_if_necessary() { 1161 assert_at_safepoint_on_vm_thread(); 1162 1163 // Capacity, free and used after the GC counted as full regions to 1164 // include the waste in the following calculations. 1165 const size_t capacity_after_gc = capacity(); 1166 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1167 1168 // This is enforced in arguments.cpp. 1169 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1170 "otherwise the code below doesn't make sense"); 1171 1172 // We don't have floating point command-line arguments 1173 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1174 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1175 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1176 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1177 1178 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1179 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1180 1181 // We have to be careful here as these two calculations can overflow 1182 // 32-bit size_t's. 1183 double used_after_gc_d = (double) used_after_gc; 1184 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1185 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1186 1187 // Let's make sure that they are both under the max heap size, which 1188 // by default will make them fit into a size_t. 1189 double desired_capacity_upper_bound = (double) max_heap_size; 1190 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1191 desired_capacity_upper_bound); 1192 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1193 desired_capacity_upper_bound); 1194 1195 // We can now safely turn them into size_t's. 1196 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1197 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1198 1199 // This assert only makes sense here, before we adjust them 1200 // with respect to the min and max heap size. 1201 assert(minimum_desired_capacity <= maximum_desired_capacity, 1202 "minimum_desired_capacity = " SIZE_FORMAT ", " 1203 "maximum_desired_capacity = " SIZE_FORMAT, 1204 minimum_desired_capacity, maximum_desired_capacity); 1205 1206 // Should not be greater than the heap max size. No need to adjust 1207 // it with respect to the heap min size as it's a lower bound (i.e., 1208 // we'll try to make the capacity larger than it, not smaller). 1209 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1210 // Should not be less than the heap min size. No need to adjust it 1211 // with respect to the heap max size as it's an upper bound (i.e., 1212 // we'll try to make the capacity smaller than it, not greater). 1213 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1214 1215 if (capacity_after_gc < minimum_desired_capacity) { 1216 // Don't expand unless it's significant 1217 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1218 1219 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1220 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1221 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1222 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1223 1224 expand(expand_bytes, _workers); 1225 1226 // No expansion, now see if we want to shrink 1227 } else if (capacity_after_gc > maximum_desired_capacity) { 1228 // Capacity too large, compute shrinking size 1229 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1230 1231 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1232 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1233 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1234 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1235 1236 shrink(shrink_bytes); 1237 } 1238 } 1239 1240 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1241 bool do_gc, 1242 bool clear_all_soft_refs, 1243 bool expect_null_mutator_alloc_region, 1244 bool* gc_succeeded) { 1245 *gc_succeeded = true; 1246 // Let's attempt the allocation first. 1247 HeapWord* result = 1248 attempt_allocation_at_safepoint(word_size, 1249 expect_null_mutator_alloc_region); 1250 if (result != NULL) { 1251 return result; 1252 } 1253 1254 // In a G1 heap, we're supposed to keep allocation from failing by 1255 // incremental pauses. Therefore, at least for now, we'll favor 1256 // expansion over collection. (This might change in the future if we can 1257 // do something smarter than full collection to satisfy a failed alloc.) 1258 result = expand_and_allocate(word_size); 1259 if (result != NULL) { 1260 return result; 1261 } 1262 1263 if (do_gc) { 1264 // Expansion didn't work, we'll try to do a Full GC. 1265 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1266 clear_all_soft_refs); 1267 } 1268 1269 return NULL; 1270 } 1271 1272 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1273 bool* succeeded) { 1274 assert_at_safepoint_on_vm_thread(); 1275 1276 // Attempts to allocate followed by Full GC. 1277 HeapWord* result = 1278 satisfy_failed_allocation_helper(word_size, 1279 true, /* do_gc */ 1280 false, /* clear_all_soft_refs */ 1281 false, /* expect_null_mutator_alloc_region */ 1282 succeeded); 1283 1284 if (result != NULL || !*succeeded) { 1285 return result; 1286 } 1287 1288 // Attempts to allocate followed by Full GC that will collect all soft references. 1289 result = satisfy_failed_allocation_helper(word_size, 1290 true, /* do_gc */ 1291 true, /* clear_all_soft_refs */ 1292 true, /* expect_null_mutator_alloc_region */ 1293 succeeded); 1294 1295 if (result != NULL || !*succeeded) { 1296 return result; 1297 } 1298 1299 // Attempts to allocate, no GC 1300 result = satisfy_failed_allocation_helper(word_size, 1301 false, /* do_gc */ 1302 false, /* clear_all_soft_refs */ 1303 true, /* expect_null_mutator_alloc_region */ 1304 succeeded); 1305 1306 if (result != NULL) { 1307 return result; 1308 } 1309 1310 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1311 "Flag should have been handled and cleared prior to this point"); 1312 1313 // What else? We might try synchronous finalization later. If the total 1314 // space available is large enough for the allocation, then a more 1315 // complete compaction phase than we've tried so far might be 1316 // appropriate. 1317 return NULL; 1318 } 1319 1320 // Attempting to expand the heap sufficiently 1321 // to support an allocation of the given "word_size". If 1322 // successful, perform the allocation and return the address of the 1323 // allocated block, or else "NULL". 1324 1325 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1326 assert_at_safepoint_on_vm_thread(); 1327 1328 _verifier->verify_region_sets_optional(); 1329 1330 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1331 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1332 word_size * HeapWordSize); 1333 1334 1335 if (expand(expand_bytes, _workers)) { 1336 _hrm->verify_optional(); 1337 _verifier->verify_region_sets_optional(); 1338 return attempt_allocation_at_safepoint(word_size, 1339 false /* expect_null_mutator_alloc_region */); 1340 } 1341 return NULL; 1342 } 1343 1344 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1345 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1346 aligned_expand_bytes = align_up(aligned_expand_bytes, 1347 HeapRegion::GrainBytes); 1348 1349 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1350 expand_bytes, aligned_expand_bytes); 1351 1352 if (is_maximal_no_gc()) { 1353 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1354 return false; 1355 } 1356 1357 double expand_heap_start_time_sec = os::elapsedTime(); 1358 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1359 assert(regions_to_expand > 0, "Must expand by at least one region"); 1360 1361 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1362 if (expand_time_ms != NULL) { 1363 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1364 } 1365 1366 if (expanded_by > 0) { 1367 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1368 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1369 policy()->record_new_heap_size(num_regions()); 1370 } else { 1371 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1372 1373 // The expansion of the virtual storage space was unsuccessful. 1374 // Let's see if it was because we ran out of swap. 1375 if (G1ExitOnExpansionFailure && 1376 _hrm->available() >= regions_to_expand) { 1377 // We had head room... 1378 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1379 } 1380 } 1381 return regions_to_expand > 0; 1382 } 1383 1384 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1385 size_t aligned_shrink_bytes = 1386 ReservedSpace::page_align_size_down(shrink_bytes); 1387 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1388 HeapRegion::GrainBytes); 1389 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1390 1391 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1392 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1393 1394 1395 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", 1396 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1397 if (num_regions_removed > 0) { 1398 policy()->record_new_heap_size(num_regions()); 1399 } else { 1400 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1401 } 1402 } 1403 1404 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1405 _verifier->verify_region_sets_optional(); 1406 1407 // We should only reach here at the end of a Full GC or during Remark which 1408 // means we should not not be holding to any GC alloc regions. The method 1409 // below will make sure of that and do any remaining clean up. 1410 _allocator->abandon_gc_alloc_regions(); 1411 1412 // Instead of tearing down / rebuilding the free lists here, we 1413 // could instead use the remove_all_pending() method on free_list to 1414 // remove only the ones that we need to remove. 1415 tear_down_region_sets(true /* free_list_only */); 1416 shrink_helper(shrink_bytes); 1417 rebuild_region_sets(true /* free_list_only */); 1418 1419 _hrm->verify_optional(); 1420 _verifier->verify_region_sets_optional(); 1421 } 1422 1423 class OldRegionSetChecker : public HeapRegionSetChecker { 1424 public: 1425 void check_mt_safety() { 1426 // Master Old Set MT safety protocol: 1427 // (a) If we're at a safepoint, operations on the master old set 1428 // should be invoked: 1429 // - by the VM thread (which will serialize them), or 1430 // - by the GC workers while holding the FreeList_lock, if we're 1431 // at a safepoint for an evacuation pause (this lock is taken 1432 // anyway when an GC alloc region is retired so that a new one 1433 // is allocated from the free list), or 1434 // - by the GC workers while holding the OldSets_lock, if we're at a 1435 // safepoint for a cleanup pause. 1436 // (b) If we're not at a safepoint, operations on the master old set 1437 // should be invoked while holding the Heap_lock. 1438 1439 if (SafepointSynchronize::is_at_safepoint()) { 1440 guarantee(Thread::current()->is_VM_thread() || 1441 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1442 "master old set MT safety protocol at a safepoint"); 1443 } else { 1444 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1445 } 1446 } 1447 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1448 const char* get_description() { return "Old Regions"; } 1449 }; 1450 1451 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1452 public: 1453 void check_mt_safety() { 1454 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1455 "May only change archive regions during initialization or safepoint."); 1456 } 1457 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1458 const char* get_description() { return "Archive Regions"; } 1459 }; 1460 1461 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1462 public: 1463 void check_mt_safety() { 1464 // Humongous Set MT safety protocol: 1465 // (a) If we're at a safepoint, operations on the master humongous 1466 // set should be invoked by either the VM thread (which will 1467 // serialize them) or by the GC workers while holding the 1468 // OldSets_lock. 1469 // (b) If we're not at a safepoint, operations on the master 1470 // humongous set should be invoked while holding the Heap_lock. 1471 1472 if (SafepointSynchronize::is_at_safepoint()) { 1473 guarantee(Thread::current()->is_VM_thread() || 1474 OldSets_lock->owned_by_self(), 1475 "master humongous set MT safety protocol at a safepoint"); 1476 } else { 1477 guarantee(Heap_lock->owned_by_self(), 1478 "master humongous set MT safety protocol outside a safepoint"); 1479 } 1480 } 1481 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1482 const char* get_description() { return "Humongous Regions"; } 1483 }; 1484 1485 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1486 CollectedHeap(), 1487 _young_gen_sampling_thread(NULL), 1488 _workers(NULL), 1489 _collector_policy(collector_policy), 1490 _card_table(NULL), 1491 _soft_ref_policy(), 1492 _old_set("Old Region Set", new OldRegionSetChecker()), 1493 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1494 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1495 _bot(NULL), 1496 _listener(), 1497 _hrm(NULL), 1498 _allocator(NULL), 1499 _verifier(NULL), 1500 _summary_bytes_used(0), 1501 _archive_allocator(NULL), 1502 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1503 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1504 _expand_heap_after_alloc_failure(true), 1505 _g1mm(NULL), 1506 _humongous_reclaim_candidates(), 1507 _has_humongous_reclaim_candidates(false), 1508 _hr_printer(), 1509 _collector_state(), 1510 _old_marking_cycles_started(0), 1511 _old_marking_cycles_completed(0), 1512 _eden(), 1513 _survivor(), 1514 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1515 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1516 _policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)), 1517 _heap_sizing_policy(NULL), 1518 _collection_set(this, _policy), 1519 _hot_card_cache(NULL), 1520 _rem_set(NULL), 1521 _dirty_card_queue_set(false), 1522 _cm(NULL), 1523 _cm_thread(NULL), 1524 _cr(NULL), 1525 _task_queues(NULL), 1526 _evacuation_failed(false), 1527 _evacuation_failed_info_array(NULL), 1528 _preserved_marks_set(true /* in_c_heap */), 1529 #ifndef PRODUCT 1530 _evacuation_failure_alot_for_current_gc(false), 1531 _evacuation_failure_alot_gc_number(0), 1532 _evacuation_failure_alot_count(0), 1533 #endif 1534 _ref_processor_stw(NULL), 1535 _is_alive_closure_stw(this), 1536 _is_subject_to_discovery_stw(this), 1537 _ref_processor_cm(NULL), 1538 _is_alive_closure_cm(this), 1539 _is_subject_to_discovery_cm(this), 1540 _in_cset_fast_test() { 1541 1542 _verifier = new G1HeapVerifier(this); 1543 1544 _allocator = new G1Allocator(this); 1545 1546 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1547 1548 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1549 1550 // Override the default _filler_array_max_size so that no humongous filler 1551 // objects are created. 1552 _filler_array_max_size = _humongous_object_threshold_in_words; 1553 1554 uint n_queues = ParallelGCThreads; 1555 _task_queues = new RefToScanQueueSet(n_queues); 1556 1557 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1558 1559 for (uint i = 0; i < n_queues; i++) { 1560 RefToScanQueue* q = new RefToScanQueue(); 1561 q->initialize(); 1562 _task_queues->register_queue(i, q); 1563 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1564 } 1565 1566 // Initialize the G1EvacuationFailureALot counters and flags. 1567 NOT_PRODUCT(reset_evacuation_should_fail();) 1568 1569 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1570 } 1571 1572 static size_t actual_reserved_page_size(ReservedSpace rs) { 1573 size_t page_size = os::vm_page_size(); 1574 if (UseLargePages) { 1575 // There are two ways to manage large page memory. 1576 // 1. OS supports committing large page memory. 1577 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1578 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1579 // we reserved memory without large page. 1580 if (os::can_commit_large_page_memory() || rs.special()) { 1581 page_size = rs.alignment(); 1582 } 1583 } 1584 1585 return page_size; 1586 } 1587 1588 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1589 size_t size, 1590 size_t translation_factor) { 1591 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1592 // Allocate a new reserved space, preferring to use large pages. 1593 ReservedSpace rs(size, preferred_page_size); 1594 size_t page_size = actual_reserved_page_size(rs); 1595 G1RegionToSpaceMapper* result = 1596 G1RegionToSpaceMapper::create_mapper(rs, 1597 size, 1598 page_size, 1599 HeapRegion::GrainBytes, 1600 translation_factor, 1601 mtGC); 1602 1603 os::trace_page_sizes_for_requested_size(description, 1604 size, 1605 preferred_page_size, 1606 page_size, 1607 rs.base(), 1608 rs.size()); 1609 1610 return result; 1611 } 1612 1613 jint G1CollectedHeap::initialize_concurrent_refinement() { 1614 jint ecode = JNI_OK; 1615 _cr = G1ConcurrentRefine::create(&ecode); 1616 return ecode; 1617 } 1618 1619 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1620 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1621 if (_young_gen_sampling_thread->osthread() == NULL) { 1622 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1623 return JNI_ENOMEM; 1624 } 1625 return JNI_OK; 1626 } 1627 1628 jint G1CollectedHeap::initialize() { 1629 os::enable_vtime(); 1630 1631 // Necessary to satisfy locking discipline assertions. 1632 1633 MutexLocker x(Heap_lock); 1634 1635 // While there are no constraints in the GC code that HeapWordSize 1636 // be any particular value, there are multiple other areas in the 1637 // system which believe this to be true (e.g. oop->object_size in some 1638 // cases incorrectly returns the size in wordSize units rather than 1639 // HeapWordSize). 1640 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1641 1642 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1643 size_t max_byte_size = _collector_policy->heap_reserved_size_bytes(); 1644 size_t heap_alignment = collector_policy()->heap_alignment(); 1645 1646 // Ensure that the sizes are properly aligned. 1647 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1648 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1649 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1650 1651 // Reserve the maximum. 1652 1653 // When compressed oops are enabled, the preferred heap base 1654 // is calculated by subtracting the requested size from the 1655 // 32Gb boundary and using the result as the base address for 1656 // heap reservation. If the requested size is not aligned to 1657 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1658 // into the ReservedHeapSpace constructor) then the actual 1659 // base of the reserved heap may end up differing from the 1660 // address that was requested (i.e. the preferred heap base). 1661 // If this happens then we could end up using a non-optimal 1662 // compressed oops mode. 1663 1664 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1665 heap_alignment); 1666 1667 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1668 1669 // Create the barrier set for the entire reserved region. 1670 G1CardTable* ct = new G1CardTable(reserved_region()); 1671 ct->initialize(); 1672 G1BarrierSet* bs = new G1BarrierSet(ct); 1673 bs->initialize(); 1674 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1675 BarrierSet::set_barrier_set(bs); 1676 _card_table = ct; 1677 1678 G1BarrierSet::satb_mark_queue_set().initialize(this, 1679 SATB_Q_CBL_mon, 1680 &bs->satb_mark_queue_buffer_allocator(), 1681 G1SATBProcessCompletedThreshold, 1682 G1SATBBufferEnqueueingThresholdPercent); 1683 1684 // process_completed_buffers_threshold and max_completed_buffers are updated 1685 // later, based on the concurrent refinement object. 1686 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1687 &bs->dirty_card_queue_buffer_allocator(), 1688 true); // init_free_ids 1689 1690 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1691 &bs->dirty_card_queue_buffer_allocator()); 1692 1693 // Create the hot card cache. 1694 _hot_card_cache = new G1HotCardCache(this); 1695 1696 // Carve out the G1 part of the heap. 1697 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1698 size_t page_size = actual_reserved_page_size(heap_rs); 1699 G1RegionToSpaceMapper* heap_storage = 1700 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1701 g1_rs.size(), 1702 page_size, 1703 HeapRegion::GrainBytes, 1704 1, 1705 mtJavaHeap); 1706 if(heap_storage == NULL) { 1707 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1708 return JNI_ERR; 1709 } 1710 1711 os::trace_page_sizes("Heap", 1712 collector_policy()->min_heap_byte_size(), 1713 max_byte_size, 1714 page_size, 1715 heap_rs.base(), 1716 heap_rs.size()); 1717 heap_storage->set_mapping_changed_listener(&_listener); 1718 1719 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1720 G1RegionToSpaceMapper* bot_storage = 1721 create_aux_memory_mapper("Block Offset Table", 1722 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1723 G1BlockOffsetTable::heap_map_factor()); 1724 1725 G1RegionToSpaceMapper* cardtable_storage = 1726 create_aux_memory_mapper("Card Table", 1727 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1728 G1CardTable::heap_map_factor()); 1729 1730 G1RegionToSpaceMapper* card_counts_storage = 1731 create_aux_memory_mapper("Card Counts Table", 1732 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1733 G1CardCounts::heap_map_factor()); 1734 1735 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1736 G1RegionToSpaceMapper* prev_bitmap_storage = 1737 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1738 G1RegionToSpaceMapper* next_bitmap_storage = 1739 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1740 1741 _hrm = HeapRegionManager::create_manager(this, _collector_policy); 1742 1743 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1744 _card_table->initialize(cardtable_storage); 1745 // Do later initialization work for concurrent refinement. 1746 _hot_card_cache->initialize(card_counts_storage); 1747 1748 // 6843694 - ensure that the maximum region index can fit 1749 // in the remembered set structures. 1750 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1751 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1752 1753 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1754 // start within the first card. 1755 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1756 // Also create a G1 rem set. 1757 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1758 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1759 1760 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1761 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1762 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1763 "too many cards per region"); 1764 1765 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1766 1767 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1768 1769 { 1770 HeapWord* start = _hrm->reserved().start(); 1771 HeapWord* end = _hrm->reserved().end(); 1772 size_t granularity = HeapRegion::GrainBytes; 1773 1774 _in_cset_fast_test.initialize(start, end, granularity); 1775 _humongous_reclaim_candidates.initialize(start, end, granularity); 1776 } 1777 1778 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1779 true /* are_GC_task_threads */, 1780 false /* are_ConcurrentGC_threads */); 1781 if (_workers == NULL) { 1782 return JNI_ENOMEM; 1783 } 1784 _workers->initialize_workers(); 1785 1786 // Create the G1ConcurrentMark data structure and thread. 1787 // (Must do this late, so that "max_regions" is defined.) 1788 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1789 if (_cm == NULL || !_cm->completed_initialization()) { 1790 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1791 return JNI_ENOMEM; 1792 } 1793 _cm_thread = _cm->cm_thread(); 1794 1795 // Now expand into the initial heap size. 1796 if (!expand(init_byte_size, _workers)) { 1797 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1798 return JNI_ENOMEM; 1799 } 1800 1801 // Perform any initialization actions delegated to the policy. 1802 policy()->init(this, &_collection_set); 1803 1804 jint ecode = initialize_concurrent_refinement(); 1805 if (ecode != JNI_OK) { 1806 return ecode; 1807 } 1808 1809 ecode = initialize_young_gen_sampling_thread(); 1810 if (ecode != JNI_OK) { 1811 return ecode; 1812 } 1813 1814 { 1815 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1816 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone()); 1817 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone()); 1818 } 1819 1820 // Here we allocate the dummy HeapRegion that is required by the 1821 // G1AllocRegion class. 1822 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1823 1824 // We'll re-use the same region whether the alloc region will 1825 // require BOT updates or not and, if it doesn't, then a non-young 1826 // region will complain that it cannot support allocations without 1827 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1828 dummy_region->set_eden(); 1829 // Make sure it's full. 1830 dummy_region->set_top(dummy_region->end()); 1831 G1AllocRegion::setup(this, dummy_region); 1832 1833 _allocator->init_mutator_alloc_region(); 1834 1835 // Do create of the monitoring and management support so that 1836 // values in the heap have been properly initialized. 1837 _g1mm = new G1MonitoringSupport(this); 1838 1839 G1StringDedup::initialize(); 1840 1841 _preserved_marks_set.init(ParallelGCThreads); 1842 1843 _collection_set.initialize(max_regions()); 1844 1845 return JNI_OK; 1846 } 1847 1848 void G1CollectedHeap::stop() { 1849 // Stop all concurrent threads. We do this to make sure these threads 1850 // do not continue to execute and access resources (e.g. logging) 1851 // that are destroyed during shutdown. 1852 _cr->stop(); 1853 _young_gen_sampling_thread->stop(); 1854 _cm_thread->stop(); 1855 if (G1StringDedup::is_enabled()) { 1856 G1StringDedup::stop(); 1857 } 1858 } 1859 1860 void G1CollectedHeap::safepoint_synchronize_begin() { 1861 SuspendibleThreadSet::synchronize(); 1862 } 1863 1864 void G1CollectedHeap::safepoint_synchronize_end() { 1865 SuspendibleThreadSet::desynchronize(); 1866 } 1867 1868 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1869 return HeapRegion::max_region_size(); 1870 } 1871 1872 void G1CollectedHeap::post_initialize() { 1873 CollectedHeap::post_initialize(); 1874 ref_processing_init(); 1875 } 1876 1877 void G1CollectedHeap::ref_processing_init() { 1878 // Reference processing in G1 currently works as follows: 1879 // 1880 // * There are two reference processor instances. One is 1881 // used to record and process discovered references 1882 // during concurrent marking; the other is used to 1883 // record and process references during STW pauses 1884 // (both full and incremental). 1885 // * Both ref processors need to 'span' the entire heap as 1886 // the regions in the collection set may be dotted around. 1887 // 1888 // * For the concurrent marking ref processor: 1889 // * Reference discovery is enabled at initial marking. 1890 // * Reference discovery is disabled and the discovered 1891 // references processed etc during remarking. 1892 // * Reference discovery is MT (see below). 1893 // * Reference discovery requires a barrier (see below). 1894 // * Reference processing may or may not be MT 1895 // (depending on the value of ParallelRefProcEnabled 1896 // and ParallelGCThreads). 1897 // * A full GC disables reference discovery by the CM 1898 // ref processor and abandons any entries on it's 1899 // discovered lists. 1900 // 1901 // * For the STW processor: 1902 // * Non MT discovery is enabled at the start of a full GC. 1903 // * Processing and enqueueing during a full GC is non-MT. 1904 // * During a full GC, references are processed after marking. 1905 // 1906 // * Discovery (may or may not be MT) is enabled at the start 1907 // of an incremental evacuation pause. 1908 // * References are processed near the end of a STW evacuation pause. 1909 // * For both types of GC: 1910 // * Discovery is atomic - i.e. not concurrent. 1911 // * Reference discovery will not need a barrier. 1912 1913 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1914 1915 // Concurrent Mark ref processor 1916 _ref_processor_cm = 1917 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1918 mt_processing, // mt processing 1919 ParallelGCThreads, // degree of mt processing 1920 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1921 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1922 false, // Reference discovery is not atomic 1923 &_is_alive_closure_cm, // is alive closure 1924 true); // allow changes to number of processing threads 1925 1926 // STW ref processor 1927 _ref_processor_stw = 1928 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1929 mt_processing, // mt processing 1930 ParallelGCThreads, // degree of mt processing 1931 (ParallelGCThreads > 1), // mt discovery 1932 ParallelGCThreads, // degree of mt discovery 1933 true, // Reference discovery is atomic 1934 &_is_alive_closure_stw, // is alive closure 1935 true); // allow changes to number of processing threads 1936 } 1937 1938 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1939 return _collector_policy; 1940 } 1941 1942 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1943 return &_soft_ref_policy; 1944 } 1945 1946 size_t G1CollectedHeap::capacity() const { 1947 return _hrm->length() * HeapRegion::GrainBytes; 1948 } 1949 1950 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1951 return _hrm->total_free_bytes(); 1952 } 1953 1954 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1955 _hot_card_cache->drain(cl, worker_i); 1956 } 1957 1958 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1959 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1960 size_t n_completed_buffers = 0; 1961 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1962 n_completed_buffers++; 1963 } 1964 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!"); 1965 phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1966 } 1967 1968 // Computes the sum of the storage used by the various regions. 1969 size_t G1CollectedHeap::used() const { 1970 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1971 if (_archive_allocator != NULL) { 1972 result += _archive_allocator->used(); 1973 } 1974 return result; 1975 } 1976 1977 size_t G1CollectedHeap::used_unlocked() const { 1978 return _summary_bytes_used; 1979 } 1980 1981 class SumUsedClosure: public HeapRegionClosure { 1982 size_t _used; 1983 public: 1984 SumUsedClosure() : _used(0) {} 1985 bool do_heap_region(HeapRegion* r) { 1986 _used += r->used(); 1987 return false; 1988 } 1989 size_t result() { return _used; } 1990 }; 1991 1992 size_t G1CollectedHeap::recalculate_used() const { 1993 SumUsedClosure blk; 1994 heap_region_iterate(&blk); 1995 return blk.result(); 1996 } 1997 1998 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1999 switch (cause) { 2000 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2001 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2002 case GCCause::_wb_conc_mark: return true; 2003 default : return false; 2004 } 2005 } 2006 2007 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2008 switch (cause) { 2009 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2010 case GCCause::_g1_humongous_allocation: return true; 2011 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2012 default: return is_user_requested_concurrent_full_gc(cause); 2013 } 2014 } 2015 2016 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2017 if(policy()->force_upgrade_to_full()) { 2018 return true; 2019 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2020 return false; 2021 } else if (has_regions_left_for_allocation()) { 2022 return false; 2023 } else { 2024 return true; 2025 } 2026 } 2027 2028 #ifndef PRODUCT 2029 void G1CollectedHeap::allocate_dummy_regions() { 2030 // Let's fill up most of the region 2031 size_t word_size = HeapRegion::GrainWords - 1024; 2032 // And as a result the region we'll allocate will be humongous. 2033 guarantee(is_humongous(word_size), "sanity"); 2034 2035 // _filler_array_max_size is set to humongous object threshold 2036 // but temporarily change it to use CollectedHeap::fill_with_object(). 2037 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2038 2039 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2040 // Let's use the existing mechanism for the allocation 2041 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2042 if (dummy_obj != NULL) { 2043 MemRegion mr(dummy_obj, word_size); 2044 CollectedHeap::fill_with_object(mr); 2045 } else { 2046 // If we can't allocate once, we probably cannot allocate 2047 // again. Let's get out of the loop. 2048 break; 2049 } 2050 } 2051 } 2052 #endif // !PRODUCT 2053 2054 void G1CollectedHeap::increment_old_marking_cycles_started() { 2055 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2056 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2057 "Wrong marking cycle count (started: %d, completed: %d)", 2058 _old_marking_cycles_started, _old_marking_cycles_completed); 2059 2060 _old_marking_cycles_started++; 2061 } 2062 2063 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2064 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2065 2066 // We assume that if concurrent == true, then the caller is a 2067 // concurrent thread that was joined the Suspendible Thread 2068 // Set. If there's ever a cheap way to check this, we should add an 2069 // assert here. 2070 2071 // Given that this method is called at the end of a Full GC or of a 2072 // concurrent cycle, and those can be nested (i.e., a Full GC can 2073 // interrupt a concurrent cycle), the number of full collections 2074 // completed should be either one (in the case where there was no 2075 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2076 // behind the number of full collections started. 2077 2078 // This is the case for the inner caller, i.e. a Full GC. 2079 assert(concurrent || 2080 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2081 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2082 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2083 "is inconsistent with _old_marking_cycles_completed = %u", 2084 _old_marking_cycles_started, _old_marking_cycles_completed); 2085 2086 // This is the case for the outer caller, i.e. the concurrent cycle. 2087 assert(!concurrent || 2088 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2089 "for outer caller (concurrent cycle): " 2090 "_old_marking_cycles_started = %u " 2091 "is inconsistent with _old_marking_cycles_completed = %u", 2092 _old_marking_cycles_started, _old_marking_cycles_completed); 2093 2094 _old_marking_cycles_completed += 1; 2095 2096 // We need to clear the "in_progress" flag in the CM thread before 2097 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2098 // is set) so that if a waiter requests another System.gc() it doesn't 2099 // incorrectly see that a marking cycle is still in progress. 2100 if (concurrent) { 2101 _cm_thread->set_idle(); 2102 } 2103 2104 // This notify_all() will ensure that a thread that called 2105 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2106 // and it's waiting for a full GC to finish will be woken up. It is 2107 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2108 FullGCCount_lock->notify_all(); 2109 } 2110 2111 void G1CollectedHeap::collect(GCCause::Cause cause) { 2112 try_collect(cause, true); 2113 } 2114 2115 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2116 assert_heap_not_locked(); 2117 2118 bool gc_succeeded; 2119 bool should_retry_gc; 2120 2121 do { 2122 should_retry_gc = false; 2123 2124 uint gc_count_before; 2125 uint old_marking_count_before; 2126 uint full_gc_count_before; 2127 2128 { 2129 MutexLocker ml(Heap_lock); 2130 2131 // Read the GC count while holding the Heap_lock 2132 gc_count_before = total_collections(); 2133 full_gc_count_before = total_full_collections(); 2134 old_marking_count_before = _old_marking_cycles_started; 2135 } 2136 2137 if (should_do_concurrent_full_gc(cause)) { 2138 // Schedule an initial-mark evacuation pause that will start a 2139 // concurrent cycle. We're setting word_size to 0 which means that 2140 // we are not requesting a post-GC allocation. 2141 VM_G1CollectForAllocation op(0, /* word_size */ 2142 gc_count_before, 2143 cause, 2144 true, /* should_initiate_conc_mark */ 2145 policy()->max_pause_time_ms()); 2146 VMThread::execute(&op); 2147 gc_succeeded = op.gc_succeeded(); 2148 if (!gc_succeeded && retry_on_gc_failure) { 2149 if (old_marking_count_before == _old_marking_cycles_started) { 2150 should_retry_gc = op.should_retry_gc(); 2151 } else { 2152 // A Full GC happened while we were trying to schedule the 2153 // concurrent cycle. No point in starting a new cycle given 2154 // that the whole heap was collected anyway. 2155 } 2156 2157 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2158 GCLocker::stall_until_clear(); 2159 } 2160 } 2161 } else { 2162 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2163 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2164 2165 // Schedule a standard evacuation pause. We're setting word_size 2166 // to 0 which means that we are not requesting a post-GC allocation. 2167 VM_G1CollectForAllocation op(0, /* word_size */ 2168 gc_count_before, 2169 cause, 2170 false, /* should_initiate_conc_mark */ 2171 policy()->max_pause_time_ms()); 2172 VMThread::execute(&op); 2173 gc_succeeded = op.gc_succeeded(); 2174 } else { 2175 // Schedule a Full GC. 2176 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2177 VMThread::execute(&op); 2178 gc_succeeded = op.gc_succeeded(); 2179 } 2180 } 2181 } while (should_retry_gc); 2182 return gc_succeeded; 2183 } 2184 2185 bool G1CollectedHeap::is_in(const void* p) const { 2186 if (_hrm->reserved().contains(p)) { 2187 // Given that we know that p is in the reserved space, 2188 // heap_region_containing() should successfully 2189 // return the containing region. 2190 HeapRegion* hr = heap_region_containing(p); 2191 return hr->is_in(p); 2192 } else { 2193 return false; 2194 } 2195 } 2196 2197 #ifdef ASSERT 2198 bool G1CollectedHeap::is_in_exact(const void* p) const { 2199 bool contains = reserved_region().contains(p); 2200 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2201 if (contains && available) { 2202 return true; 2203 } else { 2204 return false; 2205 } 2206 } 2207 #endif 2208 2209 // Iteration functions. 2210 2211 // Iterates an ObjectClosure over all objects within a HeapRegion. 2212 2213 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2214 ObjectClosure* _cl; 2215 public: 2216 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2217 bool do_heap_region(HeapRegion* r) { 2218 if (!r->is_continues_humongous()) { 2219 r->object_iterate(_cl); 2220 } 2221 return false; 2222 } 2223 }; 2224 2225 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2226 IterateObjectClosureRegionClosure blk(cl); 2227 heap_region_iterate(&blk); 2228 } 2229 2230 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2231 _hrm->iterate(cl); 2232 } 2233 2234 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2235 HeapRegionClaimer *hrclaimer, 2236 uint worker_id) const { 2237 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2238 } 2239 2240 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2241 HeapRegionClaimer *hrclaimer) const { 2242 _hrm->par_iterate(cl, hrclaimer, 0); 2243 } 2244 2245 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2246 _collection_set.iterate(cl); 2247 } 2248 2249 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2250 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2251 } 2252 2253 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2254 HeapRegion* hr = heap_region_containing(addr); 2255 return hr->block_start(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 (_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 _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 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2327 return _cm_thread->request_concurrent_phase(phase); 2328 } 2329 2330 bool G1CollectedHeap::is_heterogeneous_heap() const { 2331 return _collector_policy->is_heterogeneous_heap(); 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 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 (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 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 || collector_state()->in_initial_mark_gc()) { 2542 increment_old_marking_cycles_started(); 2543 } 2544 2545 // Fill TLAB's and such 2546 double start = os::elapsedTime(); 2547 ensure_parsability(true); 2548 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 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 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 policy()->max_pause_time_ms()); 2589 VMThread::execute(&op); 2590 2591 HeapWord* result = op.result(); 2592 bool ret_succeeded = op.prologue_succeeded() && op.gc_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 struct CountCardsClosure : public ThreadClosure { 2611 size_t _cards; 2612 CountCardsClosure() : _cards(0) {} 2613 virtual void do_thread(Thread* t) { 2614 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2615 } 2616 } count_from_threads; 2617 Threads::threads_do(&count_from_threads); 2618 2619 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2620 size_t buffer_size = dcqs.buffer_size(); 2621 size_t buffer_num = dcqs.completed_buffers_num(); 2622 2623 return buffer_size * buffer_num + count_from_threads._cards; 2624 } 2625 2626 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2627 // We don't nominate objects with many remembered set entries, on 2628 // the assumption that such objects are likely still live. 2629 HeapRegionRemSet* rem_set = r->rem_set(); 2630 2631 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2632 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2633 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2634 } 2635 2636 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2637 private: 2638 size_t _total_humongous; 2639 size_t _candidate_humongous; 2640 2641 G1DirtyCardQueue _dcq; 2642 2643 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2644 assert(region->is_starts_humongous(), "Must start a humongous object"); 2645 2646 oop obj = oop(region->bottom()); 2647 2648 // Dead objects cannot be eager reclaim candidates. Due to class 2649 // unloading it is unsafe to query their classes so we return early. 2650 if (g1h->is_obj_dead(obj, region)) { 2651 return false; 2652 } 2653 2654 // If we do not have a complete remembered set for the region, then we can 2655 // not be sure that we have all references to it. 2656 if (!region->rem_set()->is_complete()) { 2657 return false; 2658 } 2659 // Candidate selection must satisfy the following constraints 2660 // while concurrent marking is in progress: 2661 // 2662 // * In order to maintain SATB invariants, an object must not be 2663 // reclaimed if it was allocated before the start of marking and 2664 // has not had its references scanned. Such an object must have 2665 // its references (including type metadata) scanned to ensure no 2666 // live objects are missed by the marking process. Objects 2667 // allocated after the start of concurrent marking don't need to 2668 // be scanned. 2669 // 2670 // * An object must not be reclaimed if it is on the concurrent 2671 // mark stack. Objects allocated after the start of concurrent 2672 // marking are never pushed on the mark stack. 2673 // 2674 // Nominating only objects allocated after the start of concurrent 2675 // marking is sufficient to meet both constraints. This may miss 2676 // some objects that satisfy the constraints, but the marking data 2677 // structures don't support efficiently performing the needed 2678 // additional tests or scrubbing of the mark stack. 2679 // 2680 // However, we presently only nominate is_typeArray() objects. 2681 // A humongous object containing references induces remembered 2682 // set entries on other regions. In order to reclaim such an 2683 // object, those remembered sets would need to be cleaned up. 2684 // 2685 // We also treat is_typeArray() objects specially, allowing them 2686 // to be reclaimed even if allocated before the start of 2687 // concurrent mark. For this we rely on mark stack insertion to 2688 // exclude is_typeArray() objects, preventing reclaiming an object 2689 // that is in the mark stack. We also rely on the metadata for 2690 // such objects to be built-in and so ensured to be kept live. 2691 // Frequent allocation and drop of large binary blobs is an 2692 // important use case for eager reclaim, and this special handling 2693 // may reduce needed headroom. 2694 2695 return obj->is_typeArray() && 2696 g1h->is_potential_eager_reclaim_candidate(region); 2697 } 2698 2699 public: 2700 RegisterHumongousWithInCSetFastTestClosure() 2701 : _total_humongous(0), 2702 _candidate_humongous(0), 2703 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2704 } 2705 2706 virtual bool do_heap_region(HeapRegion* r) { 2707 if (!r->is_starts_humongous()) { 2708 return false; 2709 } 2710 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2711 2712 bool is_candidate = humongous_region_is_candidate(g1h, r); 2713 uint rindex = r->hrm_index(); 2714 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2715 if (is_candidate) { 2716 _candidate_humongous++; 2717 g1h->register_humongous_region_with_cset(rindex); 2718 // Is_candidate already filters out humongous object with large remembered sets. 2719 // If we have a humongous object with a few remembered sets, we simply flush these 2720 // remembered set entries into the DCQS. That will result in automatic 2721 // re-evaluation of their remembered set entries during the following evacuation 2722 // phase. 2723 if (!r->rem_set()->is_empty()) { 2724 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2725 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2726 G1CardTable* ct = g1h->card_table(); 2727 HeapRegionRemSetIterator hrrs(r->rem_set()); 2728 size_t card_index; 2729 while (hrrs.has_next(card_index)) { 2730 CardTable::CardValue* card_ptr = ct->byte_for_index(card_index); 2731 // The remembered set might contain references to already freed 2732 // regions. Filter out such entries to avoid failing card table 2733 // verification. 2734 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2735 if (*card_ptr != G1CardTable::dirty_card_val()) { 2736 *card_ptr = G1CardTable::dirty_card_val(); 2737 _dcq.enqueue(card_ptr); 2738 } 2739 } 2740 } 2741 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2742 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2743 hrrs.n_yielded(), r->rem_set()->occupied()); 2744 // We should only clear the card based remembered set here as we will not 2745 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2746 // (and probably never) we do not enter this path if there are other kind of 2747 // remembered sets for this region. 2748 r->rem_set()->clear_locked(true /* only_cardset */); 2749 // Clear_locked() above sets the state to Empty. However we want to continue 2750 // collecting remembered set entries for humongous regions that were not 2751 // reclaimed. 2752 r->rem_set()->set_state_complete(); 2753 } 2754 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2755 } 2756 _total_humongous++; 2757 2758 return false; 2759 } 2760 2761 size_t total_humongous() const { return _total_humongous; } 2762 size_t candidate_humongous() const { return _candidate_humongous; } 2763 2764 void flush_rem_set_entries() { _dcq.flush(); } 2765 }; 2766 2767 void G1CollectedHeap::register_humongous_regions_with_cset() { 2768 if (!G1EagerReclaimHumongousObjects) { 2769 phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2770 return; 2771 } 2772 double time = os::elapsed_counter(); 2773 2774 // Collect reclaim candidate information and register candidates with cset. 2775 RegisterHumongousWithInCSetFastTestClosure cl; 2776 heap_region_iterate(&cl); 2777 2778 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2779 phase_times()->record_fast_reclaim_humongous_stats(time, 2780 cl.total_humongous(), 2781 cl.candidate_humongous()); 2782 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2783 2784 // Finally flush all remembered set entries to re-check into the global DCQS. 2785 cl.flush_rem_set_entries(); 2786 } 2787 2788 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2789 public: 2790 bool do_heap_region(HeapRegion* hr) { 2791 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2792 hr->verify_rem_set(); 2793 } 2794 return false; 2795 } 2796 }; 2797 2798 uint G1CollectedHeap::num_task_queues() const { 2799 return _task_queues->size(); 2800 } 2801 2802 #if TASKQUEUE_STATS 2803 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2804 st->print_raw_cr("GC Task Stats"); 2805 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2806 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2807 } 2808 2809 void G1CollectedHeap::print_taskqueue_stats() const { 2810 if (!log_is_enabled(Trace, gc, task, stats)) { 2811 return; 2812 } 2813 Log(gc, task, stats) log; 2814 ResourceMark rm; 2815 LogStream ls(log.trace()); 2816 outputStream* st = &ls; 2817 2818 print_taskqueue_stats_hdr(st); 2819 2820 TaskQueueStats totals; 2821 const uint n = num_task_queues(); 2822 for (uint i = 0; i < n; ++i) { 2823 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2824 totals += task_queue(i)->stats; 2825 } 2826 st->print_raw("tot "); totals.print(st); st->cr(); 2827 2828 DEBUG_ONLY(totals.verify()); 2829 } 2830 2831 void G1CollectedHeap::reset_taskqueue_stats() { 2832 const uint n = num_task_queues(); 2833 for (uint i = 0; i < n; ++i) { 2834 task_queue(i)->stats.reset(); 2835 } 2836 } 2837 #endif // TASKQUEUE_STATS 2838 2839 void G1CollectedHeap::wait_for_root_region_scanning() { 2840 double scan_wait_start = os::elapsedTime(); 2841 // We have to wait until the CM threads finish scanning the 2842 // root regions as it's the only way to ensure that all the 2843 // objects on them have been correctly scanned before we start 2844 // moving them during the GC. 2845 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2846 double wait_time_ms = 0.0; 2847 if (waited) { 2848 double scan_wait_end = os::elapsedTime(); 2849 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2850 } 2851 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2852 } 2853 2854 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2855 private: 2856 G1HRPrinter* _hr_printer; 2857 public: 2858 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2859 2860 virtual bool do_heap_region(HeapRegion* r) { 2861 _hr_printer->cset(r); 2862 return false; 2863 } 2864 }; 2865 2866 void G1CollectedHeap::start_new_collection_set() { 2867 double start = os::elapsedTime(); 2868 2869 collection_set()->start_incremental_building(); 2870 2871 clear_cset_fast_test(); 2872 2873 guarantee(_eden.length() == 0, "eden should have been cleared"); 2874 policy()->transfer_survivors_to_cset(survivor()); 2875 2876 // We redo the verification but now wrt to the new CSet which 2877 // has just got initialized after the previous CSet was freed. 2878 _cm->verify_no_collection_set_oops(); 2879 2880 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2881 } 2882 2883 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms){ 2884 policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2885 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2886 2887 _cm->verify_no_collection_set_oops(); 2888 2889 if (_hr_printer.is_active()) { 2890 G1PrintCollectionSetClosure cl(&_hr_printer); 2891 _collection_set.iterate(&cl); 2892 } 2893 } 2894 2895 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2896 if (collector_state()->in_initial_mark_gc()) { 2897 return G1HeapVerifier::G1VerifyConcurrentStart; 2898 } else if (collector_state()->in_young_only_phase()) { 2899 return G1HeapVerifier::G1VerifyYoungNormal; 2900 } else { 2901 return G1HeapVerifier::G1VerifyMixed; 2902 } 2903 } 2904 2905 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2906 if (VerifyRememberedSets) { 2907 log_info(gc, verify)("[Verifying RemSets before GC]"); 2908 VerifyRegionRemSetClosure v_cl; 2909 heap_region_iterate(&v_cl); 2910 } 2911 _verifier->verify_before_gc(type); 2912 _verifier->check_bitmaps("GC Start"); 2913 } 2914 2915 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2916 if (VerifyRememberedSets) { 2917 log_info(gc, verify)("[Verifying RemSets after GC]"); 2918 VerifyRegionRemSetClosure v_cl; 2919 heap_region_iterate(&v_cl); 2920 } 2921 _verifier->verify_after_gc(type); 2922 _verifier->check_bitmaps("GC End"); 2923 } 2924 2925 void G1CollectedHeap::expand_heap_after_young_collection(){ 2926 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2927 if (expand_bytes > 0) { 2928 // No need for an ergo logging here, 2929 // expansion_amount() does this when it returns a value > 0. 2930 double expand_ms; 2931 if (!expand(expand_bytes, _workers, &expand_ms)) { 2932 // We failed to expand the heap. Cannot do anything about it. 2933 } 2934 phase_times()->record_expand_heap_time(expand_ms); 2935 } 2936 } 2937 2938 const char* G1CollectedHeap::young_gc_name() const { 2939 if (collector_state()->in_initial_mark_gc()) { 2940 return "Pause Young (Concurrent Start)"; 2941 } else if (collector_state()->in_young_only_phase()) { 2942 if (collector_state()->in_young_gc_before_mixed()) { 2943 return "Pause Young (Prepare Mixed)"; 2944 } else { 2945 return "Pause Young (Normal)"; 2946 } 2947 } else { 2948 return "Pause Young (Mixed)"; 2949 } 2950 } 2951 2952 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2953 assert_at_safepoint_on_vm_thread(); 2954 guarantee(!is_gc_active(), "collection is not reentrant"); 2955 2956 if (GCLocker::check_active_before_gc()) { 2957 return false; 2958 } 2959 2960 GCIdMark gc_id_mark; 2961 2962 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2963 ResourceMark rm; 2964 2965 policy()->note_gc_start(); 2966 2967 _gc_timer_stw->register_gc_start(); 2968 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2969 2970 wait_for_root_region_scanning(); 2971 2972 print_heap_before_gc(); 2973 print_heap_regions(); 2974 trace_heap_before_gc(_gc_tracer_stw); 2975 2976 _verifier->verify_region_sets_optional(); 2977 _verifier->verify_dirty_young_regions(); 2978 2979 // We should not be doing initial mark unless the conc mark thread is running 2980 if (!_cm_thread->should_terminate()) { 2981 // This call will decide whether this pause is an initial-mark 2982 // pause. If it is, in_initial_mark_gc() will return true 2983 // for the duration of this pause. 2984 policy()->decide_on_conc_mark_initiation(); 2985 } 2986 2987 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2988 assert(!collector_state()->in_initial_mark_gc() || 2989 collector_state()->in_young_only_phase(), "sanity"); 2990 // We also do not allow mixed GCs during marking. 2991 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2992 2993 // Record whether this pause is an initial mark. When the current 2994 // thread has completed its logging output and it's safe to signal 2995 // the CM thread, the flag's value in the policy has been reset. 2996 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2997 if (should_start_conc_mark) { 2998 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2999 } 3000 3001 // Inner scope for scope based logging, timers, and stats collection 3002 { 3003 G1EvacuationInfo evacuation_info; 3004 3005 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3006 3007 GCTraceCPUTime tcpu; 3008 3009 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3010 3011 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3012 workers()->active_workers(), 3013 Threads::number_of_non_daemon_threads()); 3014 active_workers = workers()->update_active_workers(active_workers); 3015 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3016 3017 G1MonitoringScope ms(g1mm(), 3018 false /* full_gc */, 3019 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3020 3021 G1HeapTransition heap_transition(this); 3022 size_t heap_used_bytes_before_gc = used(); 3023 3024 { 3025 IsGCActiveMark x; 3026 3027 gc_prologue(false); 3028 3029 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3030 verify_before_young_collection(verify_type); 3031 3032 { 3033 // The elapsed time induced by the start time below deliberately elides 3034 // the possible verification above. 3035 double sample_start_time_sec = os::elapsedTime(); 3036 3037 // Please see comment in g1CollectedHeap.hpp and 3038 // G1CollectedHeap::ref_processing_init() to see how 3039 // reference processing currently works in G1. 3040 _ref_processor_stw->enable_discovery(); 3041 3042 // We want to temporarily turn off discovery by the 3043 // CM ref processor, if necessary, and turn it back on 3044 // on again later if we do. Using a scoped 3045 // NoRefDiscovery object will do this. 3046 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3047 3048 policy()->record_collection_pause_start(sample_start_time_sec); 3049 3050 // Forget the current allocation region (we might even choose it to be part 3051 // of the collection set!). 3052 _allocator->release_mutator_alloc_region(); 3053 3054 calculate_collection_set(evacuation_info, target_pause_time_ms); 3055 3056 G1ParScanThreadStateSet per_thread_states(this, 3057 workers()->active_workers(), 3058 collection_set()->young_region_length(), 3059 collection_set()->optional_region_length()); 3060 pre_evacuate_collection_set(evacuation_info); 3061 3062 // Actually do the work... 3063 evacuate_collection_set(&per_thread_states); 3064 evacuate_optional_collection_set(&per_thread_states); 3065 3066 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3067 3068 start_new_collection_set(); 3069 3070 _survivor_evac_stats.adjust_desired_plab_sz(); 3071 _old_evac_stats.adjust_desired_plab_sz(); 3072 3073 if (should_start_conc_mark) { 3074 // We have to do this before we notify the CM threads that 3075 // they can start working to make sure that all the 3076 // appropriate initialization is done on the CM object. 3077 concurrent_mark()->post_initial_mark(); 3078 // Note that we don't actually trigger the CM thread at 3079 // this point. We do that later when we're sure that 3080 // the current thread has completed its logging output. 3081 } 3082 3083 allocate_dummy_regions(); 3084 3085 _allocator->init_mutator_alloc_region(); 3086 3087 expand_heap_after_young_collection(); 3088 3089 double sample_end_time_sec = os::elapsedTime(); 3090 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3091 size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3092 policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3093 } 3094 3095 verify_after_young_collection(verify_type); 3096 3097 #ifdef TRACESPINNING 3098 ParallelTaskTerminator::print_termination_counts(); 3099 #endif 3100 3101 gc_epilogue(false); 3102 } 3103 3104 // Print the remainder of the GC log output. 3105 if (evacuation_failed()) { 3106 log_info(gc)("To-space exhausted"); 3107 } 3108 3109 policy()->print_phases(); 3110 heap_transition.print(); 3111 3112 _hrm->verify_optional(); 3113 _verifier->verify_region_sets_optional(); 3114 3115 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3116 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3117 3118 print_heap_after_gc(); 3119 print_heap_regions(); 3120 trace_heap_after_gc(_gc_tracer_stw); 3121 3122 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3123 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3124 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3125 // before any GC notifications are raised. 3126 g1mm()->update_sizes(); 3127 3128 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3129 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3130 _gc_timer_stw->register_gc_end(); 3131 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3132 } 3133 // It should now be safe to tell the concurrent mark thread to start 3134 // without its logging output interfering with the logging output 3135 // that came from the pause. 3136 3137 if (should_start_conc_mark) { 3138 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3139 // thread(s) could be running concurrently with us. Make sure that anything 3140 // after this point does not assume that we are the only GC thread running. 3141 // Note: of course, the actual marking work will not start until the safepoint 3142 // itself is released in SuspendibleThreadSet::desynchronize(). 3143 do_concurrent_mark(); 3144 } 3145 3146 return true; 3147 } 3148 3149 void G1CollectedHeap::remove_self_forwarding_pointers() { 3150 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3151 workers()->run_task(&rsfp_task); 3152 } 3153 3154 void G1CollectedHeap::restore_after_evac_failure() { 3155 double remove_self_forwards_start = os::elapsedTime(); 3156 3157 remove_self_forwarding_pointers(); 3158 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3159 _preserved_marks_set.restore(&task_executor); 3160 3161 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3162 } 3163 3164 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3165 if (!_evacuation_failed) { 3166 _evacuation_failed = true; 3167 } 3168 3169 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3170 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3171 } 3172 3173 bool G1ParEvacuateFollowersClosure::offer_termination() { 3174 EventGCPhaseParallel event; 3175 G1ParScanThreadState* const pss = par_scan_state(); 3176 start_term_time(); 3177 const bool res = terminator()->offer_termination(); 3178 end_term_time(); 3179 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3180 return res; 3181 } 3182 3183 void G1ParEvacuateFollowersClosure::do_void() { 3184 EventGCPhaseParallel event; 3185 G1ParScanThreadState* const pss = par_scan_state(); 3186 pss->trim_queue(); 3187 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3188 do { 3189 EventGCPhaseParallel event; 3190 pss->steal_and_trim_queue(queues()); 3191 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3192 } while (!offer_termination()); 3193 } 3194 3195 class G1ParTask : public AbstractGangTask { 3196 protected: 3197 G1CollectedHeap* _g1h; 3198 G1ParScanThreadStateSet* _pss; 3199 RefToScanQueueSet* _queues; 3200 G1RootProcessor* _root_processor; 3201 TaskTerminator _terminator; 3202 uint _n_workers; 3203 3204 public: 3205 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3206 : AbstractGangTask("G1 collection"), 3207 _g1h(g1h), 3208 _pss(per_thread_states), 3209 _queues(task_queues), 3210 _root_processor(root_processor), 3211 _terminator(n_workers, _queues), 3212 _n_workers(n_workers) 3213 {} 3214 3215 void work(uint worker_id) { 3216 if (worker_id >= _n_workers) return; // no work needed this round 3217 3218 double start_sec = os::elapsedTime(); 3219 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3220 3221 { 3222 ResourceMark rm; 3223 HandleMark hm; 3224 3225 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3226 3227 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3228 pss->set_ref_discoverer(rp); 3229 3230 double start_strong_roots_sec = os::elapsedTime(); 3231 3232 _root_processor->evacuate_roots(pss, worker_id); 3233 3234 _g1h->rem_set()->oops_into_collection_set_do(pss, worker_id); 3235 3236 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3237 3238 double term_sec = 0.0; 3239 size_t evac_term_attempts = 0; 3240 { 3241 double start = os::elapsedTime(); 3242 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy); 3243 evac.do_void(); 3244 3245 evac_term_attempts = evac.term_attempts(); 3246 term_sec = evac.term_time(); 3247 double elapsed_sec = os::elapsedTime() - start; 3248 3249 G1GCPhaseTimes* p = _g1h->phase_times(); 3250 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3251 3252 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy, 3253 worker_id, 3254 pss->lab_waste_words() * HeapWordSize, 3255 G1GCPhaseTimes::ObjCopyLABWaste); 3256 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy, 3257 worker_id, 3258 pss->lab_undo_waste_words() * HeapWordSize, 3259 G1GCPhaseTimes::ObjCopyLABUndoWaste); 3260 3261 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3262 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3263 } 3264 3265 assert(pss->queue_is_empty(), "should be empty"); 3266 3267 // Close the inner scope so that the ResourceMark and HandleMark 3268 // destructors are executed here and are included as part of the 3269 // "GC Worker Time". 3270 } 3271 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3272 } 3273 }; 3274 3275 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3276 bool class_unloading_occurred) { 3277 uint num_workers = workers()->active_workers(); 3278 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3279 workers()->run_task(&unlink_task); 3280 #if INCLUDE_JVMCI 3281 // No parallel processing of JVMCI metadata handles for now. 3282 JVMCI::do_unloading(is_alive, class_unloading_occurred); 3283 #endif 3284 } 3285 3286 // Clean string dedup data structures. 3287 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3288 // record the durations of the phases. Hence the almost-copy. 3289 class G1StringDedupCleaningTask : public AbstractGangTask { 3290 BoolObjectClosure* _is_alive; 3291 OopClosure* _keep_alive; 3292 G1GCPhaseTimes* _phase_times; 3293 3294 public: 3295 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3296 OopClosure* keep_alive, 3297 G1GCPhaseTimes* phase_times) : 3298 AbstractGangTask("Partial Cleaning Task"), 3299 _is_alive(is_alive), 3300 _keep_alive(keep_alive), 3301 _phase_times(phase_times) 3302 { 3303 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3304 StringDedup::gc_prologue(true); 3305 } 3306 3307 ~G1StringDedupCleaningTask() { 3308 StringDedup::gc_epilogue(); 3309 } 3310 3311 void work(uint worker_id) { 3312 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3313 { 3314 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3315 StringDedupQueue::unlink_or_oops_do(&cl); 3316 } 3317 { 3318 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3319 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3320 } 3321 } 3322 }; 3323 3324 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3325 OopClosure* keep_alive, 3326 G1GCPhaseTimes* phase_times) { 3327 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3328 workers()->run_task(&cl); 3329 } 3330 3331 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3332 private: 3333 G1DirtyCardQueueSet* _queue; 3334 G1CollectedHeap* _g1h; 3335 public: 3336 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3337 _queue(queue), _g1h(g1h) { } 3338 3339 virtual void work(uint worker_id) { 3340 G1GCPhaseTimes* p = _g1h->phase_times(); 3341 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3342 3343 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3344 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3345 3346 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3347 } 3348 }; 3349 3350 void G1CollectedHeap::redirty_logged_cards() { 3351 double redirty_logged_cards_start = os::elapsedTime(); 3352 3353 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3354 dirty_card_queue_set().reset_for_par_iteration(); 3355 workers()->run_task(&redirty_task); 3356 3357 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3358 dcq.merge_bufferlists(&dirty_card_queue_set()); 3359 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3360 3361 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3362 } 3363 3364 // Weak Reference Processing support 3365 3366 bool G1STWIsAliveClosure::do_object_b(oop p) { 3367 // An object is reachable if it is outside the collection set, 3368 // or is inside and copied. 3369 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3370 } 3371 3372 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3373 assert(obj != NULL, "must not be NULL"); 3374 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3375 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3376 // may falsely indicate that this is not the case here: however the collection set only 3377 // contains old regions when concurrent mark is not running. 3378 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3379 } 3380 3381 // Non Copying Keep Alive closure 3382 class G1KeepAliveClosure: public OopClosure { 3383 G1CollectedHeap*_g1h; 3384 public: 3385 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3386 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3387 void do_oop(oop* p) { 3388 oop obj = *p; 3389 assert(obj != NULL, "the caller should have filtered out NULL values"); 3390 3391 const InCSetState cset_state =_g1h->in_cset_state(obj); 3392 if (!cset_state.is_in_cset_or_humongous()) { 3393 return; 3394 } 3395 if (cset_state.is_in_cset()) { 3396 assert( obj->is_forwarded(), "invariant" ); 3397 *p = obj->forwardee(); 3398 } else { 3399 assert(!obj->is_forwarded(), "invariant" ); 3400 assert(cset_state.is_humongous(), 3401 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3402 _g1h->set_humongous_is_live(obj); 3403 } 3404 } 3405 }; 3406 3407 // Copying Keep Alive closure - can be called from both 3408 // serial and parallel code as long as different worker 3409 // threads utilize different G1ParScanThreadState instances 3410 // and different queues. 3411 3412 class G1CopyingKeepAliveClosure: public OopClosure { 3413 G1CollectedHeap* _g1h; 3414 G1ParScanThreadState* _par_scan_state; 3415 3416 public: 3417 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3418 G1ParScanThreadState* pss): 3419 _g1h(g1h), 3420 _par_scan_state(pss) 3421 {} 3422 3423 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3424 virtual void do_oop( oop* p) { do_oop_work(p); } 3425 3426 template <class T> void do_oop_work(T* p) { 3427 oop obj = RawAccess<>::oop_load(p); 3428 3429 if (_g1h->is_in_cset_or_humongous(obj)) { 3430 // If the referent object has been forwarded (either copied 3431 // to a new location or to itself in the event of an 3432 // evacuation failure) then we need to update the reference 3433 // field and, if both reference and referent are in the G1 3434 // heap, update the RSet for the referent. 3435 // 3436 // If the referent has not been forwarded then we have to keep 3437 // it alive by policy. Therefore we have copy the referent. 3438 // 3439 // When the queue is drained (after each phase of reference processing) 3440 // the object and it's followers will be copied, the reference field set 3441 // to point to the new location, and the RSet updated. 3442 _par_scan_state->push_on_queue(p); 3443 } 3444 } 3445 }; 3446 3447 // Serial drain queue closure. Called as the 'complete_gc' 3448 // closure for each discovered list in some of the 3449 // reference processing phases. 3450 3451 class G1STWDrainQueueClosure: public VoidClosure { 3452 protected: 3453 G1CollectedHeap* _g1h; 3454 G1ParScanThreadState* _par_scan_state; 3455 3456 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3457 3458 public: 3459 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3460 _g1h(g1h), 3461 _par_scan_state(pss) 3462 { } 3463 3464 void do_void() { 3465 G1ParScanThreadState* const pss = par_scan_state(); 3466 pss->trim_queue(); 3467 } 3468 }; 3469 3470 // Parallel Reference Processing closures 3471 3472 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3473 // processing during G1 evacuation pauses. 3474 3475 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3476 private: 3477 G1CollectedHeap* _g1h; 3478 G1ParScanThreadStateSet* _pss; 3479 RefToScanQueueSet* _queues; 3480 WorkGang* _workers; 3481 3482 public: 3483 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3484 G1ParScanThreadStateSet* per_thread_states, 3485 WorkGang* workers, 3486 RefToScanQueueSet *task_queues) : 3487 _g1h(g1h), 3488 _pss(per_thread_states), 3489 _queues(task_queues), 3490 _workers(workers) 3491 { 3492 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3493 } 3494 3495 // Executes the given task using concurrent marking worker threads. 3496 virtual void execute(ProcessTask& task, uint ergo_workers); 3497 }; 3498 3499 // Gang task for possibly parallel reference processing 3500 3501 class G1STWRefProcTaskProxy: public AbstractGangTask { 3502 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3503 ProcessTask& _proc_task; 3504 G1CollectedHeap* _g1h; 3505 G1ParScanThreadStateSet* _pss; 3506 RefToScanQueueSet* _task_queues; 3507 ParallelTaskTerminator* _terminator; 3508 3509 public: 3510 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3511 G1CollectedHeap* g1h, 3512 G1ParScanThreadStateSet* per_thread_states, 3513 RefToScanQueueSet *task_queues, 3514 ParallelTaskTerminator* terminator) : 3515 AbstractGangTask("Process reference objects in parallel"), 3516 _proc_task(proc_task), 3517 _g1h(g1h), 3518 _pss(per_thread_states), 3519 _task_queues(task_queues), 3520 _terminator(terminator) 3521 {} 3522 3523 virtual void work(uint worker_id) { 3524 // The reference processing task executed by a single worker. 3525 ResourceMark rm; 3526 HandleMark hm; 3527 3528 G1STWIsAliveClosure is_alive(_g1h); 3529 3530 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3531 pss->set_ref_discoverer(NULL); 3532 3533 // Keep alive closure. 3534 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3535 3536 // Complete GC closure 3537 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3538 3539 // Call the reference processing task's work routine. 3540 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3541 3542 // Note we cannot assert that the refs array is empty here as not all 3543 // of the processing tasks (specifically phase2 - pp2_work) execute 3544 // the complete_gc closure (which ordinarily would drain the queue) so 3545 // the queue may not be empty. 3546 } 3547 }; 3548 3549 // Driver routine for parallel reference processing. 3550 // Creates an instance of the ref processing gang 3551 // task and has the worker threads execute it. 3552 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3553 assert(_workers != NULL, "Need parallel worker threads."); 3554 3555 assert(_workers->active_workers() >= ergo_workers, 3556 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3557 ergo_workers, _workers->active_workers()); 3558 TaskTerminator terminator(ergo_workers, _queues); 3559 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3560 3561 _workers->run_task(&proc_task_proxy, ergo_workers); 3562 } 3563 3564 // End of weak reference support closures 3565 3566 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3567 double ref_proc_start = os::elapsedTime(); 3568 3569 ReferenceProcessor* rp = _ref_processor_stw; 3570 assert(rp->discovery_enabled(), "should have been enabled"); 3571 3572 // Closure to test whether a referent is alive. 3573 G1STWIsAliveClosure is_alive(this); 3574 3575 // Even when parallel reference processing is enabled, the processing 3576 // of JNI refs is serial and performed serially by the current thread 3577 // rather than by a worker. The following PSS will be used for processing 3578 // JNI refs. 3579 3580 // Use only a single queue for this PSS. 3581 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3582 pss->set_ref_discoverer(NULL); 3583 assert(pss->queue_is_empty(), "pre-condition"); 3584 3585 // Keep alive closure. 3586 G1CopyingKeepAliveClosure keep_alive(this, pss); 3587 3588 // Serial Complete GC closure 3589 G1STWDrainQueueClosure drain_queue(this, pss); 3590 3591 // Setup the soft refs policy... 3592 rp->setup_policy(false); 3593 3594 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3595 3596 ReferenceProcessorStats stats; 3597 if (!rp->processing_is_mt()) { 3598 // Serial reference processing... 3599 stats = rp->process_discovered_references(&is_alive, 3600 &keep_alive, 3601 &drain_queue, 3602 NULL, 3603 pt); 3604 } else { 3605 uint no_of_gc_workers = workers()->active_workers(); 3606 3607 // Parallel reference processing 3608 assert(no_of_gc_workers <= rp->max_num_queues(), 3609 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3610 no_of_gc_workers, rp->max_num_queues()); 3611 3612 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3613 stats = rp->process_discovered_references(&is_alive, 3614 &keep_alive, 3615 &drain_queue, 3616 &par_task_executor, 3617 pt); 3618 } 3619 3620 _gc_tracer_stw->report_gc_reference_stats(stats); 3621 3622 // We have completed copying any necessary live referent objects. 3623 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3624 3625 make_pending_list_reachable(); 3626 3627 assert(!rp->discovery_enabled(), "Postcondition"); 3628 rp->verify_no_references_recorded(); 3629 3630 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3631 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3632 } 3633 3634 void G1CollectedHeap::make_pending_list_reachable() { 3635 if (collector_state()->in_initial_mark_gc()) { 3636 oop pll_head = Universe::reference_pending_list(); 3637 if (pll_head != NULL) { 3638 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3639 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3640 } 3641 } 3642 } 3643 3644 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3645 double merge_pss_time_start = os::elapsedTime(); 3646 per_thread_states->flush(); 3647 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3648 } 3649 3650 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) { 3651 _expand_heap_after_alloc_failure = true; 3652 _evacuation_failed = false; 3653 3654 // Disable the hot card cache. 3655 _hot_card_cache->reset_hot_cache_claimed_index(); 3656 _hot_card_cache->set_use_cache(false); 3657 3658 // Initialize the GC alloc regions. 3659 _allocator->init_gc_alloc_regions(evacuation_info); 3660 3661 register_humongous_regions_with_cset(); 3662 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3663 3664 rem_set()->prepare_for_oops_into_collection_set_do(); 3665 _preserved_marks_set.assert_empty(); 3666 3667 #if COMPILER2_OR_JVMCI 3668 DerivedPointerTable::clear(); 3669 #endif 3670 3671 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3672 if (collector_state()->in_initial_mark_gc()) { 3673 concurrent_mark()->pre_initial_mark(); 3674 3675 double start_clear_claimed_marks = os::elapsedTime(); 3676 3677 ClassLoaderDataGraph::clear_claimed_marks(); 3678 3679 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3680 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3681 } 3682 } 3683 3684 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3685 // Should G1EvacuationFailureALot be in effect for this GC? 3686 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3687 3688 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3689 3690 double start_par_time_sec = os::elapsedTime(); 3691 double end_par_time_sec; 3692 3693 { 3694 const uint n_workers = workers()->active_workers(); 3695 G1RootProcessor root_processor(this, n_workers); 3696 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3697 3698 workers()->run_task(&g1_par_task); 3699 end_par_time_sec = os::elapsedTime(); 3700 3701 // Closing the inner scope will execute the destructor 3702 // for the G1RootProcessor object. We record the current 3703 // elapsed time before closing the scope so that time 3704 // taken for the destructor is NOT included in the 3705 // reported parallel time. 3706 } 3707 3708 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3709 phase_times()->record_par_time(par_time_ms); 3710 3711 double code_root_fixup_time_ms = 3712 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3713 phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 3714 } 3715 3716 class G1EvacuateOptionalRegionTask : public AbstractGangTask { 3717 G1CollectedHeap* _g1h; 3718 G1ParScanThreadStateSet* _per_thread_states; 3719 G1OptionalCSet* _optional; 3720 RefToScanQueueSet* _queues; 3721 ParallelTaskTerminator _terminator; 3722 3723 Tickspan trim_ticks(G1ParScanThreadState* pss) { 3724 Tickspan copy_time = pss->trim_ticks(); 3725 pss->reset_trim_ticks(); 3726 return copy_time; 3727 } 3728 3729 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3730 G1EvacuationRootClosures* root_cls = pss->closures(); 3731 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss); 3732 3733 size_t scanned = 0; 3734 size_t claimed = 0; 3735 size_t skipped = 0; 3736 size_t used_memory = 0; 3737 3738 Ticks start = Ticks::now(); 3739 Tickspan copy_time; 3740 3741 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) { 3742 HeapRegion* hr = _optional->region_at(i); 3743 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl); 3744 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops()); 3745 copy_time += trim_ticks(pss); 3746 3747 G1ScanRSForRegionClosure scan_rs_cl(_g1h->rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id); 3748 scan_rs_cl.do_heap_region(hr); 3749 copy_time += trim_ticks(pss); 3750 scanned += scan_rs_cl.cards_scanned(); 3751 claimed += scan_rs_cl.cards_claimed(); 3752 skipped += scan_rs_cl.cards_skipped(); 3753 3754 // Chunk lists for this region is no longer needed. 3755 used_memory += pss->oops_into_optional_region(hr)->used_memory(); 3756 } 3757 3758 Tickspan scan_time = (Ticks::now() - start) - copy_time; 3759 G1GCPhaseTimes* p = _g1h->phase_times(); 3760 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds()); 3761 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds()); 3762 3763 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards); 3764 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards); 3765 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards); 3766 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory); 3767 } 3768 3769 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3770 Ticks start = Ticks::now(); 3771 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy); 3772 cl.do_void(); 3773 3774 Tickspan evac_time = (Ticks::now() - start); 3775 G1GCPhaseTimes* p = _g1h->phase_times(); 3776 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds()); 3777 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation"); 3778 } 3779 3780 public: 3781 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h, 3782 G1ParScanThreadStateSet* per_thread_states, 3783 G1OptionalCSet* cset, 3784 RefToScanQueueSet* queues, 3785 uint n_workers) : 3786 AbstractGangTask("G1 Evacuation Optional Region Task"), 3787 _g1h(g1h), 3788 _per_thread_states(per_thread_states), 3789 _optional(cset), 3790 _queues(queues), 3791 _terminator(n_workers, _queues) { 3792 } 3793 3794 void work(uint worker_id) { 3795 ResourceMark rm; 3796 HandleMark hm; 3797 3798 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3799 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3800 3801 scan_roots(pss, worker_id); 3802 evacuate_live_objects(pss, worker_id); 3803 } 3804 }; 3805 3806 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) { 3807 class G1MarkScope : public MarkScope {}; 3808 G1MarkScope code_mark_scope; 3809 3810 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers()); 3811 workers()->run_task(&task); 3812 } 3813 3814 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3815 G1OptionalCSet optional_cset(&_collection_set, per_thread_states); 3816 if (optional_cset.is_empty()) { 3817 return; 3818 } 3819 3820 if (evacuation_failed()) { 3821 return; 3822 } 3823 3824 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3825 3826 double start_time_sec = os::elapsedTime(); 3827 3828 do { 3829 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3830 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3831 3832 if (time_left_ms < 0) { 3833 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms); 3834 break; 3835 } 3836 3837 optional_cset.prepare_evacuation(time_left_ms * _policy->optional_evacuation_fraction()); 3838 if (optional_cset.prepare_failed()) { 3839 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms); 3840 break; 3841 } 3842 3843 evacuate_optional_regions(per_thread_states, &optional_cset); 3844 3845 optional_cset.complete_evacuation(); 3846 if (optional_cset.evacuation_failed()) { 3847 break; 3848 } 3849 } while (!optional_cset.is_empty()); 3850 3851 phase_times()->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0); 3852 } 3853 3854 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3855 // Also cleans the card table from temporary duplicate detection information used 3856 // during UpdateRS/ScanRS. 3857 rem_set()->cleanup_after_oops_into_collection_set_do(); 3858 3859 // Process any discovered reference objects - we have 3860 // to do this _before_ we retire the GC alloc regions 3861 // as we may have to copy some 'reachable' referent 3862 // objects (and their reachable sub-graphs) that were 3863 // not copied during the pause. 3864 process_discovered_references(per_thread_states); 3865 3866 G1STWIsAliveClosure is_alive(this); 3867 G1KeepAliveClosure keep_alive(this); 3868 3869 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3870 phase_times()->weak_phase_times()); 3871 3872 if (G1StringDedup::is_enabled()) { 3873 double string_dedup_time_ms = os::elapsedTime(); 3874 3875 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3876 3877 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3878 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3879 } 3880 3881 _allocator->release_gc_alloc_regions(evacuation_info); 3882 3883 if (evacuation_failed()) { 3884 restore_after_evac_failure(); 3885 3886 // Reset the G1EvacuationFailureALot counters and flags 3887 NOT_PRODUCT(reset_evacuation_should_fail();) 3888 3889 double recalculate_used_start = os::elapsedTime(); 3890 set_used(recalculate_used()); 3891 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3892 3893 if (_archive_allocator != NULL) { 3894 _archive_allocator->clear_used(); 3895 } 3896 for (uint i = 0; i < ParallelGCThreads; i++) { 3897 if (_evacuation_failed_info_array[i].has_failed()) { 3898 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3899 } 3900 } 3901 } else { 3902 // The "used" of the the collection set have already been subtracted 3903 // when they were freed. Add in the bytes evacuated. 3904 increase_used(policy()->bytes_copied_during_gc()); 3905 } 3906 3907 _preserved_marks_set.assert_empty(); 3908 3909 merge_per_thread_state_info(per_thread_states); 3910 3911 // Reset and re-enable the hot card cache. 3912 // Note the counts for the cards in the regions in the 3913 // collection set are reset when the collection set is freed. 3914 _hot_card_cache->reset_hot_cache(); 3915 _hot_card_cache->set_use_cache(true); 3916 3917 purge_code_root_memory(); 3918 3919 redirty_logged_cards(); 3920 3921 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3922 3923 eagerly_reclaim_humongous_regions(); 3924 3925 record_obj_copy_mem_stats(); 3926 3927 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3928 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3929 3930 #if COMPILER2_OR_JVMCI 3931 double start = os::elapsedTime(); 3932 DerivedPointerTable::update_pointers(); 3933 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3934 #endif 3935 policy()->print_age_table(); 3936 } 3937 3938 void G1CollectedHeap::record_obj_copy_mem_stats() { 3939 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3940 3941 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3942 create_g1_evac_summary(&_old_evac_stats)); 3943 } 3944 3945 void G1CollectedHeap::free_region(HeapRegion* hr, 3946 FreeRegionList* free_list, 3947 bool skip_remset, 3948 bool skip_hot_card_cache, 3949 bool locked) { 3950 assert(!hr->is_free(), "the region should not be free"); 3951 assert(!hr->is_empty(), "the region should not be empty"); 3952 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3953 assert(free_list != NULL, "pre-condition"); 3954 3955 if (G1VerifyBitmaps) { 3956 MemRegion mr(hr->bottom(), hr->end()); 3957 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3958 } 3959 3960 // Clear the card counts for this region. 3961 // Note: we only need to do this if the region is not young 3962 // (since we don't refine cards in young regions). 3963 if (!skip_hot_card_cache && !hr->is_young()) { 3964 _hot_card_cache->reset_card_counts(hr); 3965 } 3966 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3967 _policy->remset_tracker()->update_at_free(hr); 3968 free_list->add_ordered(hr); 3969 } 3970 3971 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3972 FreeRegionList* free_list) { 3973 assert(hr->is_humongous(), "this is only for humongous regions"); 3974 assert(free_list != NULL, "pre-condition"); 3975 hr->clear_humongous(); 3976 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3977 } 3978 3979 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3980 const uint humongous_regions_removed) { 3981 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3982 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3983 _old_set.bulk_remove(old_regions_removed); 3984 _humongous_set.bulk_remove(humongous_regions_removed); 3985 } 3986 3987 } 3988 3989 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3990 assert(list != NULL, "list can't be null"); 3991 if (!list->is_empty()) { 3992 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3993 _hrm->insert_list_into_free_list(list); 3994 } 3995 } 3996 3997 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3998 decrease_used(bytes); 3999 } 4000 4001 class G1FreeCollectionSetTask : public AbstractGangTask { 4002 private: 4003 4004 // Closure applied to all regions in the collection set to do work that needs to 4005 // be done serially in a single thread. 4006 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4007 private: 4008 G1EvacuationInfo* _evacuation_info; 4009 const size_t* _surviving_young_words; 4010 4011 // Bytes used in successfully evacuated regions before the evacuation. 4012 size_t _before_used_bytes; 4013 // Bytes used in unsucessfully evacuated regions before the evacuation 4014 size_t _after_used_bytes; 4015 4016 size_t _bytes_allocated_in_old_since_last_gc; 4017 4018 size_t _failure_used_words; 4019 size_t _failure_waste_words; 4020 4021 FreeRegionList _local_free_list; 4022 public: 4023 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4024 HeapRegionClosure(), 4025 _evacuation_info(evacuation_info), 4026 _surviving_young_words(surviving_young_words), 4027 _before_used_bytes(0), 4028 _after_used_bytes(0), 4029 _bytes_allocated_in_old_since_last_gc(0), 4030 _failure_used_words(0), 4031 _failure_waste_words(0), 4032 _local_free_list("Local Region List for CSet Freeing") { 4033 } 4034 4035 virtual bool do_heap_region(HeapRegion* r) { 4036 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4037 4038 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4039 g1h->clear_in_cset(r); 4040 4041 if (r->is_young()) { 4042 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4043 "Young index %d is wrong for region %u of type %s with %u young regions", 4044 r->young_index_in_cset(), 4045 r->hrm_index(), 4046 r->get_type_str(), 4047 g1h->collection_set()->young_region_length()); 4048 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4049 r->record_surv_words_in_group(words_survived); 4050 } 4051 4052 if (!r->evacuation_failed()) { 4053 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4054 _before_used_bytes += r->used(); 4055 g1h->free_region(r, 4056 &_local_free_list, 4057 true, /* skip_remset */ 4058 true, /* skip_hot_card_cache */ 4059 true /* locked */); 4060 } else { 4061 r->uninstall_surv_rate_group(); 4062 r->set_young_index_in_cset(-1); 4063 r->set_evacuation_failed(false); 4064 // When moving a young gen region to old gen, we "allocate" that whole region 4065 // there. This is in addition to any already evacuated objects. Notify the 4066 // policy about that. 4067 // Old gen regions do not cause an additional allocation: both the objects 4068 // still in the region and the ones already moved are accounted for elsewhere. 4069 if (r->is_young()) { 4070 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4071 } 4072 // The region is now considered to be old. 4073 r->set_old(); 4074 // Do some allocation statistics accounting. Regions that failed evacuation 4075 // are always made old, so there is no need to update anything in the young 4076 // gen statistics, but we need to update old gen statistics. 4077 size_t used_words = r->marked_bytes() / HeapWordSize; 4078 4079 _failure_used_words += used_words; 4080 _failure_waste_words += HeapRegion::GrainWords - used_words; 4081 4082 g1h->old_set_add(r); 4083 _after_used_bytes += r->used(); 4084 } 4085 return false; 4086 } 4087 4088 void complete_work() { 4089 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4090 4091 _evacuation_info->set_regions_freed(_local_free_list.length()); 4092 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4093 4094 g1h->prepend_to_freelist(&_local_free_list); 4095 g1h->decrement_summary_bytes(_before_used_bytes); 4096 4097 G1Policy* policy = g1h->policy(); 4098 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4099 4100 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4101 } 4102 }; 4103 4104 G1CollectionSet* _collection_set; 4105 G1SerialFreeCollectionSetClosure _cl; 4106 const size_t* _surviving_young_words; 4107 4108 size_t _rs_lengths; 4109 4110 volatile jint _serial_work_claim; 4111 4112 struct WorkItem { 4113 uint region_idx; 4114 bool is_young; 4115 bool evacuation_failed; 4116 4117 WorkItem(HeapRegion* r) { 4118 region_idx = r->hrm_index(); 4119 is_young = r->is_young(); 4120 evacuation_failed = r->evacuation_failed(); 4121 } 4122 }; 4123 4124 volatile size_t _parallel_work_claim; 4125 size_t _num_work_items; 4126 WorkItem* _work_items; 4127 4128 void do_serial_work() { 4129 // Need to grab the lock to be allowed to modify the old region list. 4130 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4131 _collection_set->iterate(&_cl); 4132 } 4133 4134 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4135 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4136 4137 HeapRegion* r = g1h->region_at(region_idx); 4138 assert(!g1h->is_on_master_free_list(r), "sanity"); 4139 4140 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4141 4142 if (!is_young) { 4143 g1h->_hot_card_cache->reset_card_counts(r); 4144 } 4145 4146 if (!evacuation_failed) { 4147 r->rem_set()->clear_locked(); 4148 } 4149 } 4150 4151 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4152 private: 4153 size_t _cur_idx; 4154 WorkItem* _work_items; 4155 public: 4156 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4157 4158 virtual bool do_heap_region(HeapRegion* r) { 4159 _work_items[_cur_idx++] = WorkItem(r); 4160 return false; 4161 } 4162 }; 4163 4164 void prepare_work() { 4165 G1PrepareFreeCollectionSetClosure cl(_work_items); 4166 _collection_set->iterate(&cl); 4167 } 4168 4169 void complete_work() { 4170 _cl.complete_work(); 4171 4172 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4173 policy->record_max_rs_lengths(_rs_lengths); 4174 policy->cset_regions_freed(); 4175 } 4176 public: 4177 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4178 AbstractGangTask("G1 Free Collection Set"), 4179 _collection_set(collection_set), 4180 _cl(evacuation_info, surviving_young_words), 4181 _surviving_young_words(surviving_young_words), 4182 _rs_lengths(0), 4183 _serial_work_claim(0), 4184 _parallel_work_claim(0), 4185 _num_work_items(collection_set->region_length()), 4186 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4187 prepare_work(); 4188 } 4189 4190 ~G1FreeCollectionSetTask() { 4191 complete_work(); 4192 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4193 } 4194 4195 // Chunk size for work distribution. The chosen value has been determined experimentally 4196 // to be a good tradeoff between overhead and achievable parallelism. 4197 static uint chunk_size() { return 32; } 4198 4199 virtual void work(uint worker_id) { 4200 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4201 4202 // Claim serial work. 4203 if (_serial_work_claim == 0) { 4204 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4205 if (value == 0) { 4206 double serial_time = os::elapsedTime(); 4207 do_serial_work(); 4208 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4209 } 4210 } 4211 4212 // Start parallel work. 4213 double young_time = 0.0; 4214 bool has_young_time = false; 4215 double non_young_time = 0.0; 4216 bool has_non_young_time = false; 4217 4218 while (true) { 4219 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4220 size_t cur = end - chunk_size(); 4221 4222 if (cur >= _num_work_items) { 4223 break; 4224 } 4225 4226 EventGCPhaseParallel event; 4227 double start_time = os::elapsedTime(); 4228 4229 end = MIN2(end, _num_work_items); 4230 4231 for (; cur < end; cur++) { 4232 bool is_young = _work_items[cur].is_young; 4233 4234 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4235 4236 double end_time = os::elapsedTime(); 4237 double time_taken = end_time - start_time; 4238 if (is_young) { 4239 young_time += time_taken; 4240 has_young_time = true; 4241 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4242 } else { 4243 non_young_time += time_taken; 4244 has_non_young_time = true; 4245 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4246 } 4247 start_time = end_time; 4248 } 4249 } 4250 4251 if (has_young_time) { 4252 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4253 } 4254 if (has_non_young_time) { 4255 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4256 } 4257 } 4258 }; 4259 4260 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4261 _eden.clear(); 4262 4263 double free_cset_start_time = os::elapsedTime(); 4264 4265 { 4266 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4267 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4268 4269 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4270 4271 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4272 cl.name(), 4273 num_workers, 4274 _collection_set.region_length()); 4275 workers()->run_task(&cl, num_workers); 4276 } 4277 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4278 4279 collection_set->clear(); 4280 } 4281 4282 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4283 private: 4284 FreeRegionList* _free_region_list; 4285 HeapRegionSet* _proxy_set; 4286 uint _humongous_objects_reclaimed; 4287 uint _humongous_regions_reclaimed; 4288 size_t _freed_bytes; 4289 public: 4290 4291 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4292 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4293 } 4294 4295 virtual bool do_heap_region(HeapRegion* r) { 4296 if (!r->is_starts_humongous()) { 4297 return false; 4298 } 4299 4300 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4301 4302 oop obj = (oop)r->bottom(); 4303 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4304 4305 // The following checks whether the humongous object is live are sufficient. 4306 // The main additional check (in addition to having a reference from the roots 4307 // or the young gen) is whether the humongous object has a remembered set entry. 4308 // 4309 // A humongous object cannot be live if there is no remembered set for it 4310 // because: 4311 // - there can be no references from within humongous starts regions referencing 4312 // the object because we never allocate other objects into them. 4313 // (I.e. there are no intra-region references that may be missed by the 4314 // remembered set) 4315 // - as soon there is a remembered set entry to the humongous starts region 4316 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4317 // until the end of a concurrent mark. 4318 // 4319 // It is not required to check whether the object has been found dead by marking 4320 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4321 // all objects allocated during that time are considered live. 4322 // SATB marking is even more conservative than the remembered set. 4323 // So if at this point in the collection there is no remembered set entry, 4324 // nobody has a reference to it. 4325 // At the start of collection we flush all refinement logs, and remembered sets 4326 // are completely up-to-date wrt to references to the humongous object. 4327 // 4328 // Other implementation considerations: 4329 // - never consider object arrays at this time because they would pose 4330 // considerable effort for cleaning up the the remembered sets. This is 4331 // required because stale remembered sets might reference locations that 4332 // are currently allocated into. 4333 uint region_idx = r->hrm_index(); 4334 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4335 !r->rem_set()->is_empty()) { 4336 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", 4337 region_idx, 4338 (size_t)obj->size() * HeapWordSize, 4339 p2i(r->bottom()), 4340 r->rem_set()->occupied(), 4341 r->rem_set()->strong_code_roots_list_length(), 4342 next_bitmap->is_marked(r->bottom()), 4343 g1h->is_humongous_reclaim_candidate(region_idx), 4344 obj->is_typeArray() 4345 ); 4346 return false; 4347 } 4348 4349 guarantee(obj->is_typeArray(), 4350 "Only eagerly reclaiming type arrays is supported, but the object " 4351 PTR_FORMAT " is not.", p2i(r->bottom())); 4352 4353 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", 4354 region_idx, 4355 (size_t)obj->size() * HeapWordSize, 4356 p2i(r->bottom()), 4357 r->rem_set()->occupied(), 4358 r->rem_set()->strong_code_roots_list_length(), 4359 next_bitmap->is_marked(r->bottom()), 4360 g1h->is_humongous_reclaim_candidate(region_idx), 4361 obj->is_typeArray() 4362 ); 4363 4364 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4365 cm->humongous_object_eagerly_reclaimed(r); 4366 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4367 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4368 region_idx, 4369 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4370 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4371 _humongous_objects_reclaimed++; 4372 do { 4373 HeapRegion* next = g1h->next_region_in_humongous(r); 4374 _freed_bytes += r->used(); 4375 r->set_containing_set(NULL); 4376 _humongous_regions_reclaimed++; 4377 g1h->free_humongous_region(r, _free_region_list); 4378 r = next; 4379 } while (r != NULL); 4380 4381 return false; 4382 } 4383 4384 uint humongous_objects_reclaimed() { 4385 return _humongous_objects_reclaimed; 4386 } 4387 4388 uint humongous_regions_reclaimed() { 4389 return _humongous_regions_reclaimed; 4390 } 4391 4392 size_t bytes_freed() const { 4393 return _freed_bytes; 4394 } 4395 }; 4396 4397 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4398 assert_at_safepoint_on_vm_thread(); 4399 4400 if (!G1EagerReclaimHumongousObjects || 4401 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4402 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4403 return; 4404 } 4405 4406 double start_time = os::elapsedTime(); 4407 4408 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4409 4410 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4411 heap_region_iterate(&cl); 4412 4413 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4414 4415 G1HRPrinter* hrp = hr_printer(); 4416 if (hrp->is_active()) { 4417 FreeRegionListIterator iter(&local_cleanup_list); 4418 while (iter.more_available()) { 4419 HeapRegion* hr = iter.get_next(); 4420 hrp->cleanup(hr); 4421 } 4422 } 4423 4424 prepend_to_freelist(&local_cleanup_list); 4425 decrement_summary_bytes(cl.bytes_freed()); 4426 4427 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4428 cl.humongous_objects_reclaimed()); 4429 } 4430 4431 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4432 public: 4433 virtual bool do_heap_region(HeapRegion* r) { 4434 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4435 G1CollectedHeap::heap()->clear_in_cset(r); 4436 r->set_young_index_in_cset(-1); 4437 return false; 4438 } 4439 }; 4440 4441 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4442 G1AbandonCollectionSetClosure cl; 4443 collection_set->iterate(&cl); 4444 4445 collection_set->clear(); 4446 collection_set->stop_incremental_building(); 4447 } 4448 4449 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4450 return _allocator->is_retained_old_region(hr); 4451 } 4452 4453 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4454 _eden.add(hr); 4455 _policy->set_region_eden(hr); 4456 } 4457 4458 #ifdef ASSERT 4459 4460 class NoYoungRegionsClosure: public HeapRegionClosure { 4461 private: 4462 bool _success; 4463 public: 4464 NoYoungRegionsClosure() : _success(true) { } 4465 bool do_heap_region(HeapRegion* r) { 4466 if (r->is_young()) { 4467 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4468 p2i(r->bottom()), p2i(r->end())); 4469 _success = false; 4470 } 4471 return false; 4472 } 4473 bool success() { return _success; } 4474 }; 4475 4476 bool G1CollectedHeap::check_young_list_empty() { 4477 bool ret = (young_regions_count() == 0); 4478 4479 NoYoungRegionsClosure closure; 4480 heap_region_iterate(&closure); 4481 ret = ret && closure.success(); 4482 4483 return ret; 4484 } 4485 4486 #endif // ASSERT 4487 4488 class TearDownRegionSetsClosure : public HeapRegionClosure { 4489 HeapRegionSet *_old_set; 4490 4491 public: 4492 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4493 4494 bool do_heap_region(HeapRegion* r) { 4495 if (r->is_old()) { 4496 _old_set->remove(r); 4497 } else if(r->is_young()) { 4498 r->uninstall_surv_rate_group(); 4499 } else { 4500 // We ignore free regions, we'll empty the free list afterwards. 4501 // We ignore humongous and archive regions, we're not tearing down these 4502 // sets. 4503 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4504 "it cannot be another type"); 4505 } 4506 return false; 4507 } 4508 4509 ~TearDownRegionSetsClosure() { 4510 assert(_old_set->is_empty(), "post-condition"); 4511 } 4512 }; 4513 4514 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4515 assert_at_safepoint_on_vm_thread(); 4516 4517 if (!free_list_only) { 4518 TearDownRegionSetsClosure cl(&_old_set); 4519 heap_region_iterate(&cl); 4520 4521 // Note that emptying the _young_list is postponed and instead done as 4522 // the first step when rebuilding the regions sets again. The reason for 4523 // this is that during a full GC string deduplication needs to know if 4524 // a collected region was young or old when the full GC was initiated. 4525 } 4526 _hrm->remove_all_free_regions(); 4527 } 4528 4529 void G1CollectedHeap::increase_used(size_t bytes) { 4530 _summary_bytes_used += bytes; 4531 } 4532 4533 void G1CollectedHeap::decrease_used(size_t bytes) { 4534 assert(_summary_bytes_used >= bytes, 4535 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4536 _summary_bytes_used, bytes); 4537 _summary_bytes_used -= bytes; 4538 } 4539 4540 void G1CollectedHeap::set_used(size_t bytes) { 4541 _summary_bytes_used = bytes; 4542 } 4543 4544 class RebuildRegionSetsClosure : public HeapRegionClosure { 4545 private: 4546 bool _free_list_only; 4547 4548 HeapRegionSet* _old_set; 4549 HeapRegionManager* _hrm; 4550 4551 size_t _total_used; 4552 4553 public: 4554 RebuildRegionSetsClosure(bool free_list_only, 4555 HeapRegionSet* old_set, 4556 HeapRegionManager* hrm) : 4557 _free_list_only(free_list_only), 4558 _old_set(old_set), _hrm(hrm), _total_used(0) { 4559 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4560 if (!free_list_only) { 4561 assert(_old_set->is_empty(), "pre-condition"); 4562 } 4563 } 4564 4565 bool do_heap_region(HeapRegion* r) { 4566 if (r->is_empty()) { 4567 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4568 // Add free regions to the free list 4569 r->set_free(); 4570 _hrm->insert_into_free_list(r); 4571 } else if (!_free_list_only) { 4572 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4573 4574 if (r->is_archive() || r->is_humongous()) { 4575 // We ignore archive and humongous regions. We left these sets unchanged. 4576 } else { 4577 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4578 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4579 r->move_to_old(); 4580 _old_set->add(r); 4581 } 4582 _total_used += r->used(); 4583 } 4584 4585 return false; 4586 } 4587 4588 size_t total_used() { 4589 return _total_used; 4590 } 4591 }; 4592 4593 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4594 assert_at_safepoint_on_vm_thread(); 4595 4596 if (!free_list_only) { 4597 _eden.clear(); 4598 _survivor.clear(); 4599 } 4600 4601 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4602 heap_region_iterate(&cl); 4603 4604 if (!free_list_only) { 4605 set_used(cl.total_used()); 4606 if (_archive_allocator != NULL) { 4607 _archive_allocator->clear_used(); 4608 } 4609 } 4610 assert(used() == recalculate_used(), 4611 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4612 used(), recalculate_used()); 4613 } 4614 4615 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4616 HeapRegion* hr = heap_region_containing(p); 4617 return hr->is_in(p); 4618 } 4619 4620 // Methods for the mutator alloc region 4621 4622 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4623 bool force) { 4624 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4625 bool should_allocate = policy()->should_allocate_mutator_region(); 4626 if (force || should_allocate) { 4627 HeapRegion* new_alloc_region = new_region(word_size, 4628 HeapRegionType::Eden, 4629 false /* do_expand */); 4630 if (new_alloc_region != NULL) { 4631 set_region_short_lived_locked(new_alloc_region); 4632 _hr_printer.alloc(new_alloc_region, !should_allocate); 4633 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4634 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4635 return new_alloc_region; 4636 } 4637 } 4638 return NULL; 4639 } 4640 4641 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4642 size_t allocated_bytes) { 4643 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4644 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4645 4646 collection_set()->add_eden_region(alloc_region); 4647 increase_used(allocated_bytes); 4648 _hr_printer.retire(alloc_region); 4649 // We update the eden sizes here, when the region is retired, 4650 // instead of when it's allocated, since this is the point that its 4651 // used space has been recorded in _summary_bytes_used. 4652 g1mm()->update_eden_size(); 4653 } 4654 4655 // Methods for the GC alloc regions 4656 4657 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4658 if (dest.is_old()) { 4659 return true; 4660 } else { 4661 return survivor_regions_count() < policy()->max_survivor_regions(); 4662 } 4663 } 4664 4665 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4666 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4667 4668 if (!has_more_regions(dest)) { 4669 return NULL; 4670 } 4671 4672 HeapRegionType type; 4673 if (dest.is_young()) { 4674 type = HeapRegionType::Survivor; 4675 } else { 4676 type = HeapRegionType::Old; 4677 } 4678 4679 HeapRegion* new_alloc_region = new_region(word_size, 4680 type, 4681 true /* do_expand */); 4682 4683 if (new_alloc_region != NULL) { 4684 if (type.is_survivor()) { 4685 new_alloc_region->set_survivor(); 4686 _survivor.add(new_alloc_region); 4687 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4688 } else { 4689 new_alloc_region->set_old(); 4690 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4691 } 4692 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4693 _hr_printer.alloc(new_alloc_region); 4694 return new_alloc_region; 4695 } 4696 return NULL; 4697 } 4698 4699 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4700 size_t allocated_bytes, 4701 InCSetState dest) { 4702 policy()->record_bytes_copied_during_gc(allocated_bytes); 4703 if (dest.is_old()) { 4704 old_set_add(alloc_region); 4705 } 4706 4707 bool const during_im = collector_state()->in_initial_mark_gc(); 4708 if (during_im && allocated_bytes > 0) { 4709 _cm->root_regions()->add(alloc_region); 4710 } 4711 _hr_printer.retire(alloc_region); 4712 } 4713 4714 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4715 bool expanded = false; 4716 uint index = _hrm->find_highest_free(&expanded); 4717 4718 if (index != G1_NO_HRM_INDEX) { 4719 if (expanded) { 4720 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4721 HeapRegion::GrainWords * HeapWordSize); 4722 } 4723 _hrm->allocate_free_regions_starting_at(index, 1); 4724 return region_at(index); 4725 } 4726 return NULL; 4727 } 4728 4729 // Optimized nmethod scanning 4730 4731 class RegisterNMethodOopClosure: public OopClosure { 4732 G1CollectedHeap* _g1h; 4733 nmethod* _nm; 4734 4735 template <class T> void do_oop_work(T* p) { 4736 T heap_oop = RawAccess<>::oop_load(p); 4737 if (!CompressedOops::is_null(heap_oop)) { 4738 oop obj = CompressedOops::decode_not_null(heap_oop); 4739 HeapRegion* hr = _g1h->heap_region_containing(obj); 4740 assert(!hr->is_continues_humongous(), 4741 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4742 " starting at " HR_FORMAT, 4743 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4744 4745 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4746 hr->add_strong_code_root_locked(_nm); 4747 } 4748 } 4749 4750 public: 4751 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4752 _g1h(g1h), _nm(nm) {} 4753 4754 void do_oop(oop* p) { do_oop_work(p); } 4755 void do_oop(narrowOop* p) { do_oop_work(p); } 4756 }; 4757 4758 class UnregisterNMethodOopClosure: public OopClosure { 4759 G1CollectedHeap* _g1h; 4760 nmethod* _nm; 4761 4762 template <class T> void do_oop_work(T* p) { 4763 T heap_oop = RawAccess<>::oop_load(p); 4764 if (!CompressedOops::is_null(heap_oop)) { 4765 oop obj = CompressedOops::decode_not_null(heap_oop); 4766 HeapRegion* hr = _g1h->heap_region_containing(obj); 4767 assert(!hr->is_continues_humongous(), 4768 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4769 " starting at " HR_FORMAT, 4770 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4771 4772 hr->remove_strong_code_root(_nm); 4773 } 4774 } 4775 4776 public: 4777 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4778 _g1h(g1h), _nm(nm) {} 4779 4780 void do_oop(oop* p) { do_oop_work(p); } 4781 void do_oop(narrowOop* p) { do_oop_work(p); } 4782 }; 4783 4784 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4785 guarantee(nm != NULL, "sanity"); 4786 RegisterNMethodOopClosure reg_cl(this, nm); 4787 nm->oops_do(®_cl); 4788 } 4789 4790 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4791 guarantee(nm != NULL, "sanity"); 4792 UnregisterNMethodOopClosure reg_cl(this, nm); 4793 nm->oops_do(®_cl, true); 4794 } 4795 4796 void G1CollectedHeap::purge_code_root_memory() { 4797 double purge_start = os::elapsedTime(); 4798 G1CodeRootSet::purge(); 4799 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4800 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4801 } 4802 4803 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4804 G1CollectedHeap* _g1h; 4805 4806 public: 4807 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4808 _g1h(g1h) {} 4809 4810 void do_code_blob(CodeBlob* cb) { 4811 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4812 if (nm == NULL) { 4813 return; 4814 } 4815 4816 _g1h->register_nmethod(nm); 4817 } 4818 }; 4819 4820 void G1CollectedHeap::rebuild_strong_code_roots() { 4821 RebuildStrongCodeRootClosure blob_cl(this); 4822 CodeCache::blobs_do(&blob_cl); 4823 } 4824 4825 void G1CollectedHeap::initialize_serviceability() { 4826 _g1mm->initialize_serviceability(); 4827 } 4828 4829 MemoryUsage G1CollectedHeap::memory_usage() { 4830 return _g1mm->memory_usage(); 4831 } 4832 4833 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4834 return _g1mm->memory_managers(); 4835 } 4836 4837 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4838 return _g1mm->memory_pools(); 4839 }