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 #include "logging/log.hpp" 83 #include "memory/allocation.hpp" 84 #include "memory/iterator.hpp" 85 #include "memory/resourceArea.hpp" 86 #include "oops/access.inline.hpp" 87 #include "oops/compressedOops.inline.hpp" 88 #include "oops/oop.inline.hpp" 89 #include "runtime/atomic.hpp" 90 #include "runtime/flags/flagSetting.hpp" 91 #include "runtime/handles.inline.hpp" 92 #include "runtime/init.hpp" 93 #include "runtime/orderAccess.hpp" 94 #include "runtime/threadSMR.hpp" 95 #include "runtime/vmThread.hpp" 96 #include "utilities/align.hpp" 97 #include "utilities/globalDefinitions.hpp" 98 #include "utilities/stack.inline.hpp" 99 100 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 101 102 // INVARIANTS/NOTES 103 // 104 // All allocation activity covered by the G1CollectedHeap interface is 105 // serialized by acquiring the HeapLock. This happens in mem_allocate 106 // and allocate_new_tlab, which are the "entry" points to the 107 // allocation code from the rest of the JVM. (Note that this does not 108 // apply to TLAB allocation, which is not part of this interface: it 109 // is done by clients of this interface.) 110 111 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 112 private: 113 size_t _num_dirtied; 114 G1CollectedHeap* _g1h; 115 G1CardTable* _g1_ct; 116 117 HeapRegion* region_for_card(CardValue* card_ptr) const { 118 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 119 } 120 121 bool will_become_free(HeapRegion* hr) const { 122 // A region will be freed by free_collection_set if the region is in the 123 // collection set and has not had an evacuation failure. 124 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 125 } 126 127 public: 128 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 129 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 130 131 bool do_card_ptr(CardValue* card_ptr, uint worker_i) { 132 HeapRegion* hr = region_for_card(card_ptr); 133 134 // Should only dirty cards in regions that won't be freed. 135 if (!will_become_free(hr)) { 136 *card_ptr = G1CardTable::dirty_card_val(); 137 _num_dirtied++; 138 } 139 140 return true; 141 } 142 143 size_t num_dirtied() const { return _num_dirtied; } 144 }; 145 146 147 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 148 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 149 } 150 151 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 152 // The from card cache is not the memory that is actually committed. So we cannot 153 // take advantage of the zero_filled parameter. 154 reset_from_card_cache(start_idx, num_regions); 155 } 156 157 158 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 159 MemRegion mr) { 160 return new HeapRegion(hrs_index, bot(), mr); 161 } 162 163 // Private methods. 164 165 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) { 166 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 167 "the only time we use this to allocate a humongous region is " 168 "when we are allocating a single humongous region"); 169 170 HeapRegion* res = _hrm->allocate_free_region(type); 171 172 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 173 // Currently, only attempts to allocate GC alloc regions set 174 // do_expand to true. So, we should only reach here during a 175 // safepoint. If this assumption changes we might have to 176 // reconsider the use of _expand_heap_after_alloc_failure. 177 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 178 179 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 180 word_size * HeapWordSize); 181 182 if (expand(word_size * HeapWordSize)) { 183 // Given that expand() succeeded in expanding the heap, and we 184 // always expand the heap by an amount aligned to the heap 185 // region size, the free list should in theory not be empty. 186 // In either case allocate_free_region() will check for NULL. 187 res = _hrm->allocate_free_region(type); 188 } else { 189 _expand_heap_after_alloc_failure = false; 190 } 191 } 192 return res; 193 } 194 195 HeapWord* 196 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 197 uint num_regions, 198 size_t word_size) { 199 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 200 assert(is_humongous(word_size), "word_size should be humongous"); 201 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 202 203 // Index of last region in the series. 204 uint last = first + num_regions - 1; 205 206 // We need to initialize the region(s) we just discovered. This is 207 // a bit tricky given that it can happen concurrently with 208 // refinement threads refining cards on these regions and 209 // potentially wanting to refine the BOT as they are scanning 210 // those cards (this can happen shortly after a cleanup; see CR 211 // 6991377). So we have to set up the region(s) carefully and in 212 // a specific order. 213 214 // The word size sum of all the regions we will allocate. 215 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 216 assert(word_size <= word_size_sum, "sanity"); 217 218 // This will be the "starts humongous" region. 219 HeapRegion* first_hr = region_at(first); 220 // The header of the new object will be placed at the bottom of 221 // the first region. 222 HeapWord* new_obj = first_hr->bottom(); 223 // This will be the new top of the new object. 224 HeapWord* obj_top = new_obj + word_size; 225 226 // First, we need to zero the header of the space that we will be 227 // allocating. When we update top further down, some refinement 228 // threads might try to scan the region. By zeroing the header we 229 // ensure that any thread that will try to scan the region will 230 // come across the zero klass word and bail out. 231 // 232 // NOTE: It would not have been correct to have used 233 // CollectedHeap::fill_with_object() and make the space look like 234 // an int array. The thread that is doing the allocation will 235 // later update the object header to a potentially different array 236 // type and, for a very short period of time, the klass and length 237 // fields will be inconsistent. This could cause a refinement 238 // thread to calculate the object size incorrectly. 239 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 240 241 // Next, pad out the unused tail of the last region with filler 242 // objects, for improved usage accounting. 243 // How many words we use for filler objects. 244 size_t word_fill_size = word_size_sum - word_size; 245 246 // How many words memory we "waste" which cannot hold a filler object. 247 size_t words_not_fillable = 0; 248 249 if (word_fill_size >= min_fill_size()) { 250 fill_with_objects(obj_top, word_fill_size); 251 } else if (word_fill_size > 0) { 252 // We have space to fill, but we cannot fit an object there. 253 words_not_fillable = word_fill_size; 254 word_fill_size = 0; 255 } 256 257 // We will set up the first region as "starts humongous". This 258 // will also update the BOT covering all the regions to reflect 259 // that there is a single object that starts at the bottom of the 260 // first region. 261 first_hr->set_starts_humongous(obj_top, word_fill_size); 262 _policy->remset_tracker()->update_at_allocate(first_hr); 263 // Then, if there are any, we will set up the "continues 264 // humongous" regions. 265 HeapRegion* hr = NULL; 266 for (uint i = first + 1; i <= last; ++i) { 267 hr = region_at(i); 268 hr->set_continues_humongous(first_hr); 269 _policy->remset_tracker()->update_at_allocate(hr); 270 } 271 272 // Up to this point no concurrent thread would have been able to 273 // do any scanning on any region in this series. All the top 274 // fields still point to bottom, so the intersection between 275 // [bottom,top] and [card_start,card_end] will be empty. Before we 276 // update the top fields, we'll do a storestore to make sure that 277 // no thread sees the update to top before the zeroing of the 278 // object header and the BOT initialization. 279 OrderAccess::storestore(); 280 281 // Now, we will update the top fields of the "continues humongous" 282 // regions except the last one. 283 for (uint i = first; i < last; ++i) { 284 hr = region_at(i); 285 hr->set_top(hr->end()); 286 } 287 288 hr = region_at(last); 289 // If we cannot fit a filler object, we must set top to the end 290 // of the humongous object, otherwise we cannot iterate the heap 291 // and the BOT will not be complete. 292 hr->set_top(hr->end() - words_not_fillable); 293 294 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 295 "obj_top should be in last region"); 296 297 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 298 299 assert(words_not_fillable == 0 || 300 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 301 "Miscalculation in humongous allocation"); 302 303 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 304 305 for (uint i = first; i <= last; ++i) { 306 hr = region_at(i); 307 _humongous_set.add(hr); 308 _hr_printer.alloc(hr); 309 } 310 311 return new_obj; 312 } 313 314 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 315 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 316 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 317 } 318 319 // If could fit into free regions w/o expansion, try. 320 // Otherwise, if can expand, do so. 321 // Otherwise, if using ex regions might help, try with ex given back. 322 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 323 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 324 325 _verifier->verify_region_sets_optional(); 326 327 uint first = G1_NO_HRM_INDEX; 328 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 329 330 if (obj_regions == 1) { 331 // Only one region to allocate, try to use a fast path by directly allocating 332 // from the free lists. Do not try to expand here, we will potentially do that 333 // later. 334 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 335 if (hr != NULL) { 336 first = hr->hrm_index(); 337 } 338 } else { 339 // Policy: Try only empty regions (i.e. already committed first). Maybe we 340 // are lucky enough to find some. 341 first = _hrm->find_contiguous_only_empty(obj_regions); 342 if (first != G1_NO_HRM_INDEX) { 343 _hrm->allocate_free_regions_starting_at(first, obj_regions); 344 } 345 } 346 347 if (first == G1_NO_HRM_INDEX) { 348 // Policy: We could not find enough regions for the humongous object in the 349 // free list. Look through the heap to find a mix of free and uncommitted regions. 350 // If so, try expansion. 351 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 352 if (first != G1_NO_HRM_INDEX) { 353 // We found something. Make sure these regions are committed, i.e. expand 354 // the heap. Alternatively we could do a defragmentation GC. 355 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 356 word_size * HeapWordSize); 357 358 _hrm->expand_at(first, obj_regions, workers()); 359 policy()->record_new_heap_size(num_regions()); 360 361 #ifdef ASSERT 362 for (uint i = first; i < first + obj_regions; ++i) { 363 HeapRegion* hr = region_at(i); 364 assert(hr->is_free(), "sanity"); 365 assert(hr->is_empty(), "sanity"); 366 assert(is_on_master_free_list(hr), "sanity"); 367 } 368 #endif 369 _hrm->allocate_free_regions_starting_at(first, obj_regions); 370 } else { 371 // Policy: Potentially trigger a defragmentation GC. 372 } 373 } 374 375 HeapWord* result = NULL; 376 if (first != G1_NO_HRM_INDEX) { 377 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 378 assert(result != NULL, "it should always return a valid result"); 379 380 // A successful humongous object allocation changes the used space 381 // information of the old generation so we need to recalculate the 382 // sizes and update the jstat counters here. 383 g1mm()->update_sizes(); 384 } 385 386 _verifier->verify_region_sets_optional(); 387 388 return result; 389 } 390 391 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 392 size_t requested_size, 393 size_t* actual_size) { 394 assert_heap_not_locked_and_not_at_safepoint(); 395 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 396 397 return attempt_allocation(min_size, requested_size, actual_size); 398 } 399 400 HeapWord* 401 G1CollectedHeap::mem_allocate(size_t word_size, 402 bool* gc_overhead_limit_was_exceeded) { 403 assert_heap_not_locked_and_not_at_safepoint(); 404 405 if (is_humongous(word_size)) { 406 return attempt_allocation_humongous(word_size); 407 } 408 size_t dummy = 0; 409 return attempt_allocation(word_size, word_size, &dummy); 410 } 411 412 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 413 ResourceMark rm; // For retrieving the thread names in log messages. 414 415 // Make sure you read the note in attempt_allocation_humongous(). 416 417 assert_heap_not_locked_and_not_at_safepoint(); 418 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 419 "be called for humongous allocation requests"); 420 421 // We should only get here after the first-level allocation attempt 422 // (attempt_allocation()) failed to allocate. 423 424 // We will loop until a) we manage to successfully perform the 425 // allocation or b) we successfully schedule a collection which 426 // fails to perform the allocation. b) is the only case when we'll 427 // return NULL. 428 HeapWord* result = NULL; 429 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 430 bool should_try_gc; 431 uint gc_count_before; 432 433 { 434 MutexLockerEx x(Heap_lock); 435 result = _allocator->attempt_allocation_locked(word_size); 436 if (result != NULL) { 437 return result; 438 } 439 440 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 441 // This is different to when only GCLocker::needs_gc() is set: try to avoid 442 // waiting because the GCLocker is active to not wait too long. 443 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) { 444 // No need for an ergo message here, can_expand_young_list() does this when 445 // it returns true. 446 result = _allocator->attempt_allocation_force(word_size); 447 if (result != NULL) { 448 return result; 449 } 450 } 451 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 452 // the GCLocker initiated GC has been performed and then retry. This includes 453 // the case when the GC Locker is not active but has not been performed. 454 should_try_gc = !GCLocker::needs_gc(); 455 // Read the GC count while still holding the Heap_lock. 456 gc_count_before = total_collections(); 457 } 458 459 if (should_try_gc) { 460 bool succeeded; 461 result = do_collection_pause(word_size, gc_count_before, &succeeded, 462 GCCause::_g1_inc_collection_pause); 463 if (result != NULL) { 464 assert(succeeded, "only way to get back a non-NULL result"); 465 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 466 Thread::current()->name(), p2i(result)); 467 return result; 468 } 469 470 if (succeeded) { 471 // We successfully scheduled a collection which failed to allocate. No 472 // point in trying to allocate further. We'll just return NULL. 473 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 474 SIZE_FORMAT " words", Thread::current()->name(), word_size); 475 return NULL; 476 } 477 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 478 Thread::current()->name(), word_size); 479 } else { 480 // Failed to schedule a collection. 481 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 482 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 483 SIZE_FORMAT " words", Thread::current()->name(), word_size); 484 return NULL; 485 } 486 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 487 // The GCLocker is either active or the GCLocker initiated 488 // GC has not yet been performed. Stall until it is and 489 // then retry the allocation. 490 GCLocker::stall_until_clear(); 491 gclocker_retry_count += 1; 492 } 493 494 // We can reach here if we were unsuccessful in scheduling a 495 // collection (because another thread beat us to it) or if we were 496 // stalled due to the GC locker. In either can we should retry the 497 // allocation attempt in case another thread successfully 498 // performed a collection and reclaimed enough space. We do the 499 // first attempt (without holding the Heap_lock) here and the 500 // follow-on attempt will be at the start of the next loop 501 // iteration (after taking the Heap_lock). 502 size_t dummy = 0; 503 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 504 if (result != NULL) { 505 return result; 506 } 507 508 // Give a warning if we seem to be looping forever. 509 if ((QueuedAllocationWarningCount > 0) && 510 (try_count % QueuedAllocationWarningCount == 0)) { 511 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 512 Thread::current()->name(), try_count, word_size); 513 } 514 } 515 516 ShouldNotReachHere(); 517 return NULL; 518 } 519 520 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 521 assert_at_safepoint_on_vm_thread(); 522 if (_archive_allocator == NULL) { 523 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 524 } 525 } 526 527 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 528 // Allocations in archive regions cannot be of a size that would be considered 529 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 530 // may be different at archive-restore time. 531 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 532 } 533 534 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 535 assert_at_safepoint_on_vm_thread(); 536 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 537 if (is_archive_alloc_too_large(word_size)) { 538 return NULL; 539 } 540 return _archive_allocator->archive_mem_allocate(word_size); 541 } 542 543 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 544 size_t end_alignment_in_bytes) { 545 assert_at_safepoint_on_vm_thread(); 546 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 547 548 // Call complete_archive to do the real work, filling in the MemRegion 549 // array with the archive regions. 550 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 551 delete _archive_allocator; 552 _archive_allocator = NULL; 553 } 554 555 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 556 assert(ranges != NULL, "MemRegion array NULL"); 557 assert(count != 0, "No MemRegions provided"); 558 MemRegion reserved = _hrm->reserved(); 559 for (size_t i = 0; i < count; i++) { 560 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 561 return false; 562 } 563 } 564 return true; 565 } 566 567 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 568 size_t count, 569 bool open) { 570 assert(!is_init_completed(), "Expect to be called at JVM init time"); 571 assert(ranges != NULL, "MemRegion array NULL"); 572 assert(count != 0, "No MemRegions provided"); 573 MutexLockerEx x(Heap_lock); 574 575 MemRegion reserved = _hrm->reserved(); 576 HeapWord* prev_last_addr = NULL; 577 HeapRegion* prev_last_region = NULL; 578 579 // Temporarily disable pretouching of heap pages. This interface is used 580 // when mmap'ing archived heap data in, so pre-touching is wasted. 581 FlagSetting fs(AlwaysPreTouch, false); 582 583 // Enable archive object checking used by G1MarkSweep. We have to let it know 584 // about each archive range, so that objects in those ranges aren't marked. 585 G1ArchiveAllocator::enable_archive_object_check(); 586 587 // For each specified MemRegion range, allocate the corresponding G1 588 // regions and mark them as archive regions. We expect the ranges 589 // in ascending starting address order, without overlap. 590 for (size_t i = 0; i < count; i++) { 591 MemRegion curr_range = ranges[i]; 592 HeapWord* start_address = curr_range.start(); 593 size_t word_size = curr_range.word_size(); 594 HeapWord* last_address = curr_range.last(); 595 size_t commits = 0; 596 597 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 598 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 599 p2i(start_address), p2i(last_address)); 600 guarantee(start_address > prev_last_addr, 601 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 602 p2i(start_address), p2i(prev_last_addr)); 603 prev_last_addr = last_address; 604 605 // Check for ranges that start in the same G1 region in which the previous 606 // range ended, and adjust the start address so we don't try to allocate 607 // the same region again. If the current range is entirely within that 608 // region, skip it, just adjusting the recorded top. 609 HeapRegion* start_region = _hrm->addr_to_region(start_address); 610 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 611 start_address = start_region->end(); 612 if (start_address > last_address) { 613 increase_used(word_size * HeapWordSize); 614 start_region->set_top(last_address + 1); 615 continue; 616 } 617 start_region->set_top(start_address); 618 curr_range = MemRegion(start_address, last_address + 1); 619 start_region = _hrm->addr_to_region(start_address); 620 } 621 622 // Perform the actual region allocation, exiting if it fails. 623 // Then note how much new space we have allocated. 624 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 625 return false; 626 } 627 increase_used(word_size * HeapWordSize); 628 if (commits != 0) { 629 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 630 HeapRegion::GrainWords * HeapWordSize * commits); 631 632 } 633 634 // Mark each G1 region touched by the range as archive, add it to 635 // the old set, and set top. 636 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 637 HeapRegion* last_region = _hrm->addr_to_region(last_address); 638 prev_last_region = last_region; 639 640 while (curr_region != NULL) { 641 assert(curr_region->is_empty() && !curr_region->is_pinned(), 642 "Region already in use (index %u)", curr_region->hrm_index()); 643 if (open) { 644 curr_region->set_open_archive(); 645 } else { 646 curr_region->set_closed_archive(); 647 } 648 _hr_printer.alloc(curr_region); 649 _archive_set.add(curr_region); 650 HeapWord* top; 651 HeapRegion* next_region; 652 if (curr_region != last_region) { 653 top = curr_region->end(); 654 next_region = _hrm->next_region_in_heap(curr_region); 655 } else { 656 top = last_address + 1; 657 next_region = NULL; 658 } 659 curr_region->set_top(top); 660 curr_region->set_first_dead(top); 661 curr_region->set_end_of_live(top); 662 curr_region = next_region; 663 } 664 665 // Notify mark-sweep of the archive 666 G1ArchiveAllocator::set_range_archive(curr_range, open); 667 } 668 return true; 669 } 670 671 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 672 assert(!is_init_completed(), "Expect to be called at JVM init time"); 673 assert(ranges != NULL, "MemRegion array NULL"); 674 assert(count != 0, "No MemRegions provided"); 675 MemRegion reserved = _hrm->reserved(); 676 HeapWord *prev_last_addr = NULL; 677 HeapRegion* prev_last_region = NULL; 678 679 // For each MemRegion, create filler objects, if needed, in the G1 regions 680 // that contain the address range. The address range actually within the 681 // MemRegion will not be modified. That is assumed to have been initialized 682 // elsewhere, probably via an mmap of archived heap data. 683 MutexLockerEx x(Heap_lock); 684 for (size_t i = 0; i < count; i++) { 685 HeapWord* start_address = ranges[i].start(); 686 HeapWord* last_address = ranges[i].last(); 687 688 assert(reserved.contains(start_address) && reserved.contains(last_address), 689 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 690 p2i(start_address), p2i(last_address)); 691 assert(start_address > prev_last_addr, 692 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 693 p2i(start_address), p2i(prev_last_addr)); 694 695 HeapRegion* start_region = _hrm->addr_to_region(start_address); 696 HeapRegion* last_region = _hrm->addr_to_region(last_address); 697 HeapWord* bottom_address = start_region->bottom(); 698 699 // Check for a range beginning in the same region in which the 700 // previous one ended. 701 if (start_region == prev_last_region) { 702 bottom_address = prev_last_addr + 1; 703 } 704 705 // Verify that the regions were all marked as archive regions by 706 // alloc_archive_regions. 707 HeapRegion* curr_region = start_region; 708 while (curr_region != NULL) { 709 guarantee(curr_region->is_archive(), 710 "Expected archive region at index %u", curr_region->hrm_index()); 711 if (curr_region != last_region) { 712 curr_region = _hrm->next_region_in_heap(curr_region); 713 } else { 714 curr_region = NULL; 715 } 716 } 717 718 prev_last_addr = last_address; 719 prev_last_region = last_region; 720 721 // Fill the memory below the allocated range with dummy object(s), 722 // if the region bottom does not match the range start, or if the previous 723 // range ended within the same G1 region, and there is a gap. 724 if (start_address != bottom_address) { 725 size_t fill_size = pointer_delta(start_address, bottom_address); 726 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 727 increase_used(fill_size * HeapWordSize); 728 } 729 } 730 } 731 732 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 733 size_t desired_word_size, 734 size_t* actual_word_size) { 735 assert_heap_not_locked_and_not_at_safepoint(); 736 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 737 "be called for humongous allocation requests"); 738 739 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 740 741 if (result == NULL) { 742 *actual_word_size = desired_word_size; 743 result = attempt_allocation_slow(desired_word_size); 744 } 745 746 assert_heap_not_locked(); 747 if (result != NULL) { 748 assert(*actual_word_size != 0, "Actual size must have been set here"); 749 dirty_young_block(result, *actual_word_size); 750 } else { 751 *actual_word_size = 0; 752 } 753 754 return result; 755 } 756 757 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 758 assert(!is_init_completed(), "Expect to be called at JVM init time"); 759 assert(ranges != NULL, "MemRegion array NULL"); 760 assert(count != 0, "No MemRegions provided"); 761 MemRegion reserved = _hrm->reserved(); 762 HeapWord* prev_last_addr = NULL; 763 HeapRegion* prev_last_region = NULL; 764 size_t size_used = 0; 765 size_t uncommitted_regions = 0; 766 767 // For each Memregion, free the G1 regions that constitute it, and 768 // notify mark-sweep that the range is no longer to be considered 'archive.' 769 MutexLockerEx x(Heap_lock); 770 for (size_t i = 0; i < count; i++) { 771 HeapWord* start_address = ranges[i].start(); 772 HeapWord* last_address = ranges[i].last(); 773 774 assert(reserved.contains(start_address) && reserved.contains(last_address), 775 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 776 p2i(start_address), p2i(last_address)); 777 assert(start_address > prev_last_addr, 778 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 779 p2i(start_address), p2i(prev_last_addr)); 780 size_used += ranges[i].byte_size(); 781 prev_last_addr = last_address; 782 783 HeapRegion* start_region = _hrm->addr_to_region(start_address); 784 HeapRegion* last_region = _hrm->addr_to_region(last_address); 785 786 // Check for ranges that start in the same G1 region in which the previous 787 // range ended, and adjust the start address so we don't try to free 788 // the same region again. If the current range is entirely within that 789 // region, skip it. 790 if (start_region == prev_last_region) { 791 start_address = start_region->end(); 792 if (start_address > last_address) { 793 continue; 794 } 795 start_region = _hrm->addr_to_region(start_address); 796 } 797 prev_last_region = last_region; 798 799 // After verifying that each region was marked as an archive region by 800 // alloc_archive_regions, set it free and empty and uncommit it. 801 HeapRegion* curr_region = start_region; 802 while (curr_region != NULL) { 803 guarantee(curr_region->is_archive(), 804 "Expected archive region at index %u", curr_region->hrm_index()); 805 uint curr_index = curr_region->hrm_index(); 806 _archive_set.remove(curr_region); 807 curr_region->set_free(); 808 curr_region->set_top(curr_region->bottom()); 809 if (curr_region != last_region) { 810 curr_region = _hrm->next_region_in_heap(curr_region); 811 } else { 812 curr_region = NULL; 813 } 814 _hrm->shrink_at(curr_index, 1); 815 uncommitted_regions++; 816 } 817 818 // Notify mark-sweep that this is no longer an archive range. 819 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 820 } 821 822 if (uncommitted_regions != 0) { 823 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 824 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 825 } 826 decrease_used(size_used); 827 } 828 829 oop G1CollectedHeap::materialize_archived_object(oop obj) { 830 assert(obj != NULL, "archived obj is NULL"); 831 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 832 833 // Loading an archived object makes it strongly reachable. If it is 834 // loaded during concurrent marking, it must be enqueued to the SATB 835 // queue, shading the previously white object gray. 836 G1BarrierSet::enqueue(obj); 837 838 return obj; 839 } 840 841 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 842 ResourceMark rm; // For retrieving the thread names in log messages. 843 844 // The structure of this method has a lot of similarities to 845 // attempt_allocation_slow(). The reason these two were not merged 846 // into a single one is that such a method would require several "if 847 // allocation is not humongous do this, otherwise do that" 848 // conditional paths which would obscure its flow. In fact, an early 849 // version of this code did use a unified method which was harder to 850 // follow and, as a result, it had subtle bugs that were hard to 851 // track down. So keeping these two methods separate allows each to 852 // be more readable. It will be good to keep these two in sync as 853 // much as possible. 854 855 assert_heap_not_locked_and_not_at_safepoint(); 856 assert(is_humongous(word_size), "attempt_allocation_humongous() " 857 "should only be called for humongous allocations"); 858 859 // Humongous objects can exhaust the heap quickly, so we should check if we 860 // need to start a marking cycle at each humongous object allocation. We do 861 // the check before we do the actual allocation. The reason for doing it 862 // before the allocation is that we avoid having to keep track of the newly 863 // allocated memory while we do a GC. 864 if (policy()->need_to_start_conc_mark("concurrent humongous allocation", 865 word_size)) { 866 collect(GCCause::_g1_humongous_allocation); 867 } 868 869 // We will loop until a) we manage to successfully perform the 870 // allocation or b) we successfully schedule a collection which 871 // fails to perform the allocation. b) is the only case when we'll 872 // return NULL. 873 HeapWord* result = NULL; 874 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 875 bool should_try_gc; 876 uint gc_count_before; 877 878 879 { 880 MutexLockerEx x(Heap_lock); 881 882 // Given that humongous objects are not allocated in young 883 // regions, we'll first try to do the allocation without doing a 884 // collection hoping that there's enough space in the heap. 885 result = humongous_obj_allocate(word_size); 886 if (result != NULL) { 887 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 888 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 889 return result; 890 } 891 892 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 893 // the GCLocker initiated GC has been performed and then retry. This includes 894 // the case when the GC Locker is not active but has not been performed. 895 should_try_gc = !GCLocker::needs_gc(); 896 // Read the GC count while still holding the Heap_lock. 897 gc_count_before = total_collections(); 898 } 899 900 if (should_try_gc) { 901 bool succeeded; 902 result = do_collection_pause(word_size, gc_count_before, &succeeded, 903 GCCause::_g1_humongous_allocation); 904 if (result != NULL) { 905 assert(succeeded, "only way to get back a non-NULL result"); 906 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 907 Thread::current()->name(), p2i(result)); 908 return result; 909 } 910 911 if (succeeded) { 912 // We successfully scheduled a collection which failed to allocate. No 913 // point in trying to allocate further. We'll just return NULL. 914 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 915 SIZE_FORMAT " words", Thread::current()->name(), word_size); 916 return NULL; 917 } 918 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 919 Thread::current()->name(), word_size); 920 } else { 921 // Failed to schedule a collection. 922 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 923 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 924 SIZE_FORMAT " words", Thread::current()->name(), word_size); 925 return NULL; 926 } 927 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 928 // The GCLocker is either active or the GCLocker initiated 929 // GC has not yet been performed. Stall until it is and 930 // then retry the allocation. 931 GCLocker::stall_until_clear(); 932 gclocker_retry_count += 1; 933 } 934 935 936 // We can reach here if we were unsuccessful in scheduling a 937 // collection (because another thread beat us to it) or if we were 938 // stalled due to the GC locker. In either can we should retry the 939 // allocation attempt in case another thread successfully 940 // performed a collection and reclaimed enough space. 941 // Humongous object allocation always needs a lock, so we wait for the retry 942 // in the next iteration of the loop, unlike for the regular iteration case. 943 // Give a warning if we seem to be looping forever. 944 945 if ((QueuedAllocationWarningCount > 0) && 946 (try_count % QueuedAllocationWarningCount == 0)) { 947 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 948 Thread::current()->name(), try_count, word_size); 949 } 950 } 951 952 ShouldNotReachHere(); 953 return NULL; 954 } 955 956 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 957 bool expect_null_mutator_alloc_region) { 958 assert_at_safepoint_on_vm_thread(); 959 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 960 "the current alloc region was unexpectedly found to be non-NULL"); 961 962 if (!is_humongous(word_size)) { 963 return _allocator->attempt_allocation_locked(word_size); 964 } else { 965 HeapWord* result = humongous_obj_allocate(word_size); 966 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) { 967 collector_state()->set_initiate_conc_mark_if_possible(true); 968 } 969 return result; 970 } 971 972 ShouldNotReachHere(); 973 } 974 975 class PostCompactionPrinterClosure: public HeapRegionClosure { 976 private: 977 G1HRPrinter* _hr_printer; 978 public: 979 bool do_heap_region(HeapRegion* hr) { 980 assert(!hr->is_young(), "not expecting to find young regions"); 981 _hr_printer->post_compaction(hr); 982 return false; 983 } 984 985 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 986 : _hr_printer(hr_printer) { } 987 }; 988 989 void G1CollectedHeap::print_hrm_post_compaction() { 990 if (_hr_printer.is_active()) { 991 PostCompactionPrinterClosure cl(hr_printer()); 992 heap_region_iterate(&cl); 993 } 994 } 995 996 void G1CollectedHeap::abort_concurrent_cycle() { 997 // If we start the compaction before the CM threads finish 998 // scanning the root regions we might trip them over as we'll 999 // be moving objects / updating references. So let's wait until 1000 // they are done. By telling them to abort, they should complete 1001 // early. 1002 _cm->root_regions()->abort(); 1003 _cm->root_regions()->wait_until_scan_finished(); 1004 1005 // Disable discovery and empty the discovered lists 1006 // for the CM ref processor. 1007 _ref_processor_cm->disable_discovery(); 1008 _ref_processor_cm->abandon_partial_discovery(); 1009 _ref_processor_cm->verify_no_references_recorded(); 1010 1011 // Abandon current iterations of concurrent marking and concurrent 1012 // refinement, if any are in progress. 1013 concurrent_mark()->concurrent_cycle_abort(); 1014 } 1015 1016 void G1CollectedHeap::prepare_heap_for_full_collection() { 1017 // Make sure we'll choose a new allocation region afterwards. 1018 _allocator->release_mutator_alloc_region(); 1019 _allocator->abandon_gc_alloc_regions(); 1020 1021 // We may have added regions to the current incremental collection 1022 // set between the last GC or pause and now. We need to clear the 1023 // incremental collection set and then start rebuilding it afresh 1024 // after this full GC. 1025 abandon_collection_set(collection_set()); 1026 1027 tear_down_region_sets(false /* free_list_only */); 1028 1029 hrm()->prepare_for_full_collection_start(); 1030 } 1031 1032 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1033 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1034 assert(used() == recalculate_used(), "Should be equal"); 1035 _verifier->verify_region_sets_optional(); 1036 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1037 _verifier->check_bitmaps("Full GC Start"); 1038 } 1039 1040 void G1CollectedHeap::prepare_heap_for_mutators() { 1041 hrm()->prepare_for_full_collection_end(); 1042 1043 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1044 ClassLoaderDataGraph::purge(); 1045 MetaspaceUtils::verify_metrics(); 1046 1047 // Prepare heap for normal collections. 1048 assert(num_free_regions() == 0, "we should not have added any free regions"); 1049 rebuild_region_sets(false /* free_list_only */); 1050 abort_refinement(); 1051 resize_heap_if_necessary(); 1052 1053 // Rebuild the strong code root lists for each region 1054 rebuild_strong_code_roots(); 1055 1056 // Purge code root memory 1057 purge_code_root_memory(); 1058 1059 // Start a new incremental collection set for the next pause 1060 start_new_collection_set(); 1061 1062 _allocator->init_mutator_alloc_region(); 1063 1064 // Post collection state updates. 1065 MetaspaceGC::compute_new_size(); 1066 } 1067 1068 void G1CollectedHeap::abort_refinement() { 1069 if (_hot_card_cache->use_cache()) { 1070 _hot_card_cache->reset_hot_cache(); 1071 } 1072 1073 // Discard all remembered set updates. 1074 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1075 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1076 } 1077 1078 void G1CollectedHeap::verify_after_full_collection() { 1079 _hrm->verify_optional(); 1080 _verifier->verify_region_sets_optional(); 1081 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1082 // Clear the previous marking bitmap, if needed for bitmap verification. 1083 // Note we cannot do this when we clear the next marking bitmap in 1084 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1085 // objects marked during a full GC against the previous bitmap. 1086 // But we need to clear it before calling check_bitmaps below since 1087 // the full GC has compacted objects and updated TAMS but not updated 1088 // the prev bitmap. 1089 if (G1VerifyBitmaps) { 1090 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification"); 1091 _cm->clear_prev_bitmap(workers()); 1092 } 1093 // This call implicitly verifies that the next bitmap is clear after Full GC. 1094 _verifier->check_bitmaps("Full GC End"); 1095 1096 // At this point there should be no regions in the 1097 // entire heap tagged as young. 1098 assert(check_young_list_empty(), "young list should be empty at this point"); 1099 1100 // Note: since we've just done a full GC, concurrent 1101 // marking is no longer active. Therefore we need not 1102 // re-enable reference discovery for the CM ref processor. 1103 // That will be done at the start of the next marking cycle. 1104 // We also know that the STW processor should no longer 1105 // discover any new references. 1106 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1107 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1108 _ref_processor_stw->verify_no_references_recorded(); 1109 _ref_processor_cm->verify_no_references_recorded(); 1110 } 1111 1112 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1113 // Post collection logging. 1114 // We should do this after we potentially resize the heap so 1115 // that all the COMMIT / UNCOMMIT events are generated before 1116 // the compaction events. 1117 print_hrm_post_compaction(); 1118 heap_transition->print(); 1119 print_heap_after_gc(); 1120 print_heap_regions(); 1121 #ifdef TRACESPINNING 1122 ParallelTaskTerminator::print_termination_counts(); 1123 #endif 1124 } 1125 1126 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1127 bool clear_all_soft_refs) { 1128 assert_at_safepoint_on_vm_thread(); 1129 1130 if (GCLocker::check_active_before_gc()) { 1131 // Full GC was not completed. 1132 return false; 1133 } 1134 1135 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1136 soft_ref_policy()->should_clear_all_soft_refs(); 1137 1138 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1139 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1140 1141 collector.prepare_collection(); 1142 collector.collect(); 1143 collector.complete_collection(); 1144 1145 // Full collection was successfully completed. 1146 return true; 1147 } 1148 1149 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1150 // Currently, there is no facility in the do_full_collection(bool) API to notify 1151 // the caller that the collection did not succeed (e.g., because it was locked 1152 // out by the GC locker). So, right now, we'll ignore the return value. 1153 bool dummy = do_full_collection(true, /* explicit_gc */ 1154 clear_all_soft_refs); 1155 } 1156 1157 void G1CollectedHeap::resize_heap_if_necessary() { 1158 assert_at_safepoint_on_vm_thread(); 1159 1160 // Capacity, free and used after the GC counted as full regions to 1161 // include the waste in the following calculations. 1162 const size_t capacity_after_gc = capacity(); 1163 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1164 1165 // This is enforced in arguments.cpp. 1166 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1167 "otherwise the code below doesn't make sense"); 1168 1169 // We don't have floating point command-line arguments 1170 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1171 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1172 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1173 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1174 1175 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1176 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1177 1178 // We have to be careful here as these two calculations can overflow 1179 // 32-bit size_t's. 1180 double used_after_gc_d = (double) used_after_gc; 1181 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1182 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1183 1184 // Let's make sure that they are both under the max heap size, which 1185 // by default will make them fit into a size_t. 1186 double desired_capacity_upper_bound = (double) max_heap_size; 1187 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1188 desired_capacity_upper_bound); 1189 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1190 desired_capacity_upper_bound); 1191 1192 // We can now safely turn them into size_t's. 1193 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1194 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1195 1196 // This assert only makes sense here, before we adjust them 1197 // with respect to the min and max heap size. 1198 assert(minimum_desired_capacity <= maximum_desired_capacity, 1199 "minimum_desired_capacity = " SIZE_FORMAT ", " 1200 "maximum_desired_capacity = " SIZE_FORMAT, 1201 minimum_desired_capacity, maximum_desired_capacity); 1202 1203 // Should not be greater than the heap max size. No need to adjust 1204 // it with respect to the heap min size as it's a lower bound (i.e., 1205 // we'll try to make the capacity larger than it, not smaller). 1206 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1207 // Should not be less than the heap min size. No need to adjust it 1208 // with respect to the heap max size as it's an upper bound (i.e., 1209 // we'll try to make the capacity smaller than it, not greater). 1210 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1211 1212 if (capacity_after_gc < minimum_desired_capacity) { 1213 // Don't expand unless it's significant 1214 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1215 1216 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1217 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1218 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1219 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1220 1221 expand(expand_bytes, _workers); 1222 1223 // No expansion, now see if we want to shrink 1224 } else if (capacity_after_gc > maximum_desired_capacity) { 1225 // Capacity too large, compute shrinking size 1226 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1227 1228 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1229 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1230 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1231 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1232 1233 shrink(shrink_bytes); 1234 } 1235 } 1236 1237 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1238 bool do_gc, 1239 bool clear_all_soft_refs, 1240 bool expect_null_mutator_alloc_region, 1241 bool* gc_succeeded) { 1242 *gc_succeeded = true; 1243 // Let's attempt the allocation first. 1244 HeapWord* result = 1245 attempt_allocation_at_safepoint(word_size, 1246 expect_null_mutator_alloc_region); 1247 if (result != NULL) { 1248 return result; 1249 } 1250 1251 // In a G1 heap, we're supposed to keep allocation from failing by 1252 // incremental pauses. Therefore, at least for now, we'll favor 1253 // expansion over collection. (This might change in the future if we can 1254 // do something smarter than full collection to satisfy a failed alloc.) 1255 result = expand_and_allocate(word_size); 1256 if (result != NULL) { 1257 return result; 1258 } 1259 1260 if (do_gc) { 1261 // Expansion didn't work, we'll try to do a Full GC. 1262 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1263 clear_all_soft_refs); 1264 } 1265 1266 return NULL; 1267 } 1268 1269 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1270 bool* succeeded) { 1271 assert_at_safepoint_on_vm_thread(); 1272 1273 // Attempts to allocate followed by Full GC. 1274 HeapWord* result = 1275 satisfy_failed_allocation_helper(word_size, 1276 true, /* do_gc */ 1277 false, /* clear_all_soft_refs */ 1278 false, /* expect_null_mutator_alloc_region */ 1279 succeeded); 1280 1281 if (result != NULL || !*succeeded) { 1282 return result; 1283 } 1284 1285 // Attempts to allocate followed by Full GC that will collect all soft references. 1286 result = satisfy_failed_allocation_helper(word_size, 1287 true, /* do_gc */ 1288 true, /* clear_all_soft_refs */ 1289 true, /* expect_null_mutator_alloc_region */ 1290 succeeded); 1291 1292 if (result != NULL || !*succeeded) { 1293 return result; 1294 } 1295 1296 // Attempts to allocate, no GC 1297 result = satisfy_failed_allocation_helper(word_size, 1298 false, /* do_gc */ 1299 false, /* clear_all_soft_refs */ 1300 true, /* expect_null_mutator_alloc_region */ 1301 succeeded); 1302 1303 if (result != NULL) { 1304 return result; 1305 } 1306 1307 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1308 "Flag should have been handled and cleared prior to this point"); 1309 1310 // What else? We might try synchronous finalization later. If the total 1311 // space available is large enough for the allocation, then a more 1312 // complete compaction phase than we've tried so far might be 1313 // appropriate. 1314 return NULL; 1315 } 1316 1317 // Attempting to expand the heap sufficiently 1318 // to support an allocation of the given "word_size". If 1319 // successful, perform the allocation and return the address of the 1320 // allocated block, or else "NULL". 1321 1322 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1323 assert_at_safepoint_on_vm_thread(); 1324 1325 _verifier->verify_region_sets_optional(); 1326 1327 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1328 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1329 word_size * HeapWordSize); 1330 1331 1332 if (expand(expand_bytes, _workers)) { 1333 _hrm->verify_optional(); 1334 _verifier->verify_region_sets_optional(); 1335 return attempt_allocation_at_safepoint(word_size, 1336 false /* expect_null_mutator_alloc_region */); 1337 } 1338 return NULL; 1339 } 1340 1341 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1342 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1343 aligned_expand_bytes = align_up(aligned_expand_bytes, 1344 HeapRegion::GrainBytes); 1345 1346 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1347 expand_bytes, aligned_expand_bytes); 1348 1349 if (is_maximal_no_gc()) { 1350 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1351 return false; 1352 } 1353 1354 double expand_heap_start_time_sec = os::elapsedTime(); 1355 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1356 assert(regions_to_expand > 0, "Must expand by at least one region"); 1357 1358 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1359 if (expand_time_ms != NULL) { 1360 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1361 } 1362 1363 if (expanded_by > 0) { 1364 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1365 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1366 policy()->record_new_heap_size(num_regions()); 1367 } else { 1368 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1369 1370 // The expansion of the virtual storage space was unsuccessful. 1371 // Let's see if it was because we ran out of swap. 1372 if (G1ExitOnExpansionFailure && 1373 _hrm->available() >= regions_to_expand) { 1374 // We had head room... 1375 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1376 } 1377 } 1378 return regions_to_expand > 0; 1379 } 1380 1381 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1382 size_t aligned_shrink_bytes = 1383 ReservedSpace::page_align_size_down(shrink_bytes); 1384 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1385 HeapRegion::GrainBytes); 1386 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1387 1388 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1389 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1390 1391 1392 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", 1393 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1394 if (num_regions_removed > 0) { 1395 policy()->record_new_heap_size(num_regions()); 1396 } else { 1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1398 } 1399 } 1400 1401 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1402 _verifier->verify_region_sets_optional(); 1403 1404 // We should only reach here at the end of a Full GC or during Remark which 1405 // means we should not not be holding to any GC alloc regions. The method 1406 // below will make sure of that and do any remaining clean up. 1407 _allocator->abandon_gc_alloc_regions(); 1408 1409 // Instead of tearing down / rebuilding the free lists here, we 1410 // could instead use the remove_all_pending() method on free_list to 1411 // remove only the ones that we need to remove. 1412 tear_down_region_sets(true /* free_list_only */); 1413 shrink_helper(shrink_bytes); 1414 rebuild_region_sets(true /* free_list_only */); 1415 1416 _hrm->verify_optional(); 1417 _verifier->verify_region_sets_optional(); 1418 } 1419 1420 class OldRegionSetChecker : public HeapRegionSetChecker { 1421 public: 1422 void check_mt_safety() { 1423 // Master Old Set MT safety protocol: 1424 // (a) If we're at a safepoint, operations on the master old set 1425 // should be invoked: 1426 // - by the VM thread (which will serialize them), or 1427 // - by the GC workers while holding the FreeList_lock, if we're 1428 // at a safepoint for an evacuation pause (this lock is taken 1429 // anyway when an GC alloc region is retired so that a new one 1430 // is allocated from the free list), or 1431 // - by the GC workers while holding the OldSets_lock, if we're at a 1432 // safepoint for a cleanup pause. 1433 // (b) If we're not at a safepoint, operations on the master old set 1434 // should be invoked while holding the Heap_lock. 1435 1436 if (SafepointSynchronize::is_at_safepoint()) { 1437 guarantee(Thread::current()->is_VM_thread() || 1438 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1439 "master old set MT safety protocol at a safepoint"); 1440 } else { 1441 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1442 } 1443 } 1444 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1445 const char* get_description() { return "Old Regions"; } 1446 }; 1447 1448 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1449 public: 1450 void check_mt_safety() { 1451 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1452 "May only change archive regions during initialization or safepoint."); 1453 } 1454 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1455 const char* get_description() { return "Archive Regions"; } 1456 }; 1457 1458 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1459 public: 1460 void check_mt_safety() { 1461 // Humongous Set MT safety protocol: 1462 // (a) If we're at a safepoint, operations on the master humongous 1463 // set should be invoked by either the VM thread (which will 1464 // serialize them) or by the GC workers while holding the 1465 // OldSets_lock. 1466 // (b) If we're not at a safepoint, operations on the master 1467 // humongous set should be invoked while holding the Heap_lock. 1468 1469 if (SafepointSynchronize::is_at_safepoint()) { 1470 guarantee(Thread::current()->is_VM_thread() || 1471 OldSets_lock->owned_by_self(), 1472 "master humongous set MT safety protocol at a safepoint"); 1473 } else { 1474 guarantee(Heap_lock->owned_by_self(), 1475 "master humongous set MT safety protocol outside a safepoint"); 1476 } 1477 } 1478 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1479 const char* get_description() { return "Humongous Regions"; } 1480 }; 1481 1482 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1483 CollectedHeap(), 1484 _young_gen_sampling_thread(NULL), 1485 _workers(NULL), 1486 _collector_policy(collector_policy), 1487 _card_table(NULL), 1488 _soft_ref_policy(), 1489 _old_set("Old Region Set", new OldRegionSetChecker()), 1490 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1491 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1492 _bot(NULL), 1493 _listener(), 1494 _hrm(NULL), 1495 _allocator(NULL), 1496 _verifier(NULL), 1497 _summary_bytes_used(0), 1498 _archive_allocator(NULL), 1499 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1500 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1501 _expand_heap_after_alloc_failure(true), 1502 _g1mm(NULL), 1503 _humongous_reclaim_candidates(), 1504 _has_humongous_reclaim_candidates(false), 1505 _hr_printer(), 1506 _collector_state(), 1507 _old_marking_cycles_started(0), 1508 _old_marking_cycles_completed(0), 1509 _eden(), 1510 _survivor(), 1511 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1512 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1513 _policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)), 1514 _heap_sizing_policy(NULL), 1515 _collection_set(this, _policy), 1516 _hot_card_cache(NULL), 1517 _rem_set(NULL), 1518 _dirty_card_queue_set(false), 1519 _cm(NULL), 1520 _cm_thread(NULL), 1521 _cr(NULL), 1522 _task_queues(NULL), 1523 _evacuation_failed(false), 1524 _evacuation_failed_info_array(NULL), 1525 _preserved_marks_set(true /* in_c_heap */), 1526 #ifndef PRODUCT 1527 _evacuation_failure_alot_for_current_gc(false), 1528 _evacuation_failure_alot_gc_number(0), 1529 _evacuation_failure_alot_count(0), 1530 #endif 1531 _ref_processor_stw(NULL), 1532 _is_alive_closure_stw(this), 1533 _is_subject_to_discovery_stw(this), 1534 _ref_processor_cm(NULL), 1535 _is_alive_closure_cm(this), 1536 _is_subject_to_discovery_cm(this), 1537 _in_cset_fast_test() { 1538 1539 _verifier = new G1HeapVerifier(this); 1540 1541 _allocator = new G1Allocator(this); 1542 1543 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics()); 1544 1545 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1546 1547 // Override the default _filler_array_max_size so that no humongous filler 1548 // objects are created. 1549 _filler_array_max_size = _humongous_object_threshold_in_words; 1550 1551 uint n_queues = ParallelGCThreads; 1552 _task_queues = new RefToScanQueueSet(n_queues); 1553 1554 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1555 1556 for (uint i = 0; i < n_queues; i++) { 1557 RefToScanQueue* q = new RefToScanQueue(); 1558 q->initialize(); 1559 _task_queues->register_queue(i, q); 1560 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1561 } 1562 1563 // Initialize the G1EvacuationFailureALot counters and flags. 1564 NOT_PRODUCT(reset_evacuation_should_fail();) 1565 1566 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1567 } 1568 1569 static size_t actual_reserved_page_size(ReservedSpace rs) { 1570 size_t page_size = os::vm_page_size(); 1571 if (UseLargePages) { 1572 // There are two ways to manage large page memory. 1573 // 1. OS supports committing large page memory. 1574 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1575 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1576 // we reserved memory without large page. 1577 if (os::can_commit_large_page_memory() || rs.special()) { 1578 page_size = rs.alignment(); 1579 } 1580 } 1581 1582 return page_size; 1583 } 1584 1585 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1586 size_t size, 1587 size_t translation_factor) { 1588 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1589 // Allocate a new reserved space, preferring to use large pages. 1590 ReservedSpace rs(size, preferred_page_size); 1591 size_t page_size = actual_reserved_page_size(rs); 1592 G1RegionToSpaceMapper* result = 1593 G1RegionToSpaceMapper::create_mapper(rs, 1594 size, 1595 page_size, 1596 HeapRegion::GrainBytes, 1597 translation_factor, 1598 mtGC); 1599 1600 os::trace_page_sizes_for_requested_size(description, 1601 size, 1602 preferred_page_size, 1603 page_size, 1604 rs.base(), 1605 rs.size()); 1606 1607 return result; 1608 } 1609 1610 jint G1CollectedHeap::initialize_concurrent_refinement() { 1611 jint ecode = JNI_OK; 1612 _cr = G1ConcurrentRefine::create(&ecode); 1613 return ecode; 1614 } 1615 1616 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1617 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1618 if (_young_gen_sampling_thread->osthread() == NULL) { 1619 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1620 return JNI_ENOMEM; 1621 } 1622 return JNI_OK; 1623 } 1624 1625 jint G1CollectedHeap::initialize() { 1626 os::enable_vtime(); 1627 1628 // Necessary to satisfy locking discipline assertions. 1629 1630 MutexLocker x(Heap_lock); 1631 1632 // While there are no constraints in the GC code that HeapWordSize 1633 // be any particular value, there are multiple other areas in the 1634 // system which believe this to be true (e.g. oop->object_size in some 1635 // cases incorrectly returns the size in wordSize units rather than 1636 // HeapWordSize). 1637 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1638 1639 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1640 size_t max_byte_size = _collector_policy->heap_reserved_size_bytes(); 1641 size_t heap_alignment = collector_policy()->heap_alignment(); 1642 1643 // Ensure that the sizes are properly aligned. 1644 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1645 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1646 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1647 1648 // Reserve the maximum. 1649 1650 // When compressed oops are enabled, the preferred heap base 1651 // is calculated by subtracting the requested size from the 1652 // 32Gb boundary and using the result as the base address for 1653 // heap reservation. If the requested size is not aligned to 1654 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1655 // into the ReservedHeapSpace constructor) then the actual 1656 // base of the reserved heap may end up differing from the 1657 // address that was requested (i.e. the preferred heap base). 1658 // If this happens then we could end up using a non-optimal 1659 // compressed oops mode. 1660 1661 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1662 heap_alignment); 1663 1664 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1665 1666 // Create the barrier set for the entire reserved region. 1667 G1CardTable* ct = new G1CardTable(reserved_region()); 1668 ct->initialize(); 1669 G1BarrierSet* bs = new G1BarrierSet(ct); 1670 bs->initialize(); 1671 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1672 BarrierSet::set_barrier_set(bs); 1673 _card_table = ct; 1674 1675 G1BarrierSet::satb_mark_queue_set().initialize(this, 1676 SATB_Q_CBL_mon, 1677 &bs->satb_mark_queue_buffer_allocator(), 1678 G1SATBProcessCompletedThreshold, 1679 G1SATBBufferEnqueueingThresholdPercent); 1680 1681 // process_completed_buffers_threshold and max_completed_buffers are updated 1682 // later, based on the concurrent refinement object. 1683 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1684 &bs->dirty_card_queue_buffer_allocator(), 1685 true); // init_free_ids 1686 1687 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1688 &bs->dirty_card_queue_buffer_allocator()); 1689 1690 // Create the hot card cache. 1691 _hot_card_cache = new G1HotCardCache(this); 1692 1693 // Carve out the G1 part of the heap. 1694 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1695 size_t page_size = actual_reserved_page_size(heap_rs); 1696 G1RegionToSpaceMapper* heap_storage = 1697 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1698 g1_rs.size(), 1699 page_size, 1700 HeapRegion::GrainBytes, 1701 1, 1702 mtJavaHeap); 1703 if(heap_storage == NULL) { 1704 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1705 return JNI_ERR; 1706 } 1707 1708 os::trace_page_sizes("Heap", 1709 collector_policy()->min_heap_byte_size(), 1710 max_byte_size, 1711 page_size, 1712 heap_rs.base(), 1713 heap_rs.size()); 1714 heap_storage->set_mapping_changed_listener(&_listener); 1715 1716 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1717 G1RegionToSpaceMapper* bot_storage = 1718 create_aux_memory_mapper("Block Offset Table", 1719 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1720 G1BlockOffsetTable::heap_map_factor()); 1721 1722 G1RegionToSpaceMapper* cardtable_storage = 1723 create_aux_memory_mapper("Card Table", 1724 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1725 G1CardTable::heap_map_factor()); 1726 1727 G1RegionToSpaceMapper* card_counts_storage = 1728 create_aux_memory_mapper("Card Counts Table", 1729 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1730 G1CardCounts::heap_map_factor()); 1731 1732 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1733 G1RegionToSpaceMapper* prev_bitmap_storage = 1734 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1735 G1RegionToSpaceMapper* next_bitmap_storage = 1736 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1737 1738 _hrm = HeapRegionManager::create_manager(this, _collector_policy); 1739 1740 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1741 _card_table->initialize(cardtable_storage); 1742 // Do later initialization work for concurrent refinement. 1743 _hot_card_cache->initialize(card_counts_storage); 1744 1745 // 6843694 - ensure that the maximum region index can fit 1746 // in the remembered set structures. 1747 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1748 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1749 1750 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1751 // start within the first card. 1752 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1753 // Also create a G1 rem set. 1754 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1755 _rem_set->initialize(max_reserved_capacity(), max_regions()); 1756 1757 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1758 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1759 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1760 "too many cards per region"); 1761 1762 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1763 1764 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1765 1766 { 1767 HeapWord* start = _hrm->reserved().start(); 1768 HeapWord* end = _hrm->reserved().end(); 1769 size_t granularity = HeapRegion::GrainBytes; 1770 1771 _in_cset_fast_test.initialize(start, end, granularity); 1772 _humongous_reclaim_candidates.initialize(start, end, granularity); 1773 } 1774 1775 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1776 true /* are_GC_task_threads */, 1777 false /* are_ConcurrentGC_threads */); 1778 if (_workers == NULL) { 1779 return JNI_ENOMEM; 1780 } 1781 _workers->initialize_workers(); 1782 1783 // Create the G1ConcurrentMark data structure and thread. 1784 // (Must do this late, so that "max_regions" is defined.) 1785 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1786 if (_cm == NULL || !_cm->completed_initialization()) { 1787 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1788 return JNI_ENOMEM; 1789 } 1790 _cm_thread = _cm->cm_thread(); 1791 1792 // Now expand into the initial heap size. 1793 if (!expand(init_byte_size, _workers)) { 1794 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1795 return JNI_ENOMEM; 1796 } 1797 1798 // Perform any initialization actions delegated to the policy. 1799 policy()->init(this, &_collection_set); 1800 1801 jint ecode = initialize_concurrent_refinement(); 1802 if (ecode != JNI_OK) { 1803 return ecode; 1804 } 1805 1806 ecode = initialize_young_gen_sampling_thread(); 1807 if (ecode != JNI_OK) { 1808 return ecode; 1809 } 1810 1811 { 1812 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1813 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone()); 1814 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone()); 1815 } 1816 1817 // Here we allocate the dummy HeapRegion that is required by the 1818 // G1AllocRegion class. 1819 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1820 1821 // We'll re-use the same region whether the alloc region will 1822 // require BOT updates or not and, if it doesn't, then a non-young 1823 // region will complain that it cannot support allocations without 1824 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1825 dummy_region->set_eden(); 1826 // Make sure it's full. 1827 dummy_region->set_top(dummy_region->end()); 1828 G1AllocRegion::setup(this, dummy_region); 1829 1830 _allocator->init_mutator_alloc_region(); 1831 1832 // Do create of the monitoring and management support so that 1833 // values in the heap have been properly initialized. 1834 _g1mm = new G1MonitoringSupport(this); 1835 1836 G1StringDedup::initialize(); 1837 1838 _preserved_marks_set.init(ParallelGCThreads); 1839 1840 _collection_set.initialize(max_regions()); 1841 1842 return JNI_OK; 1843 } 1844 1845 void G1CollectedHeap::stop() { 1846 // Stop all concurrent threads. We do this to make sure these threads 1847 // do not continue to execute and access resources (e.g. logging) 1848 // that are destroyed during shutdown. 1849 _cr->stop(); 1850 _young_gen_sampling_thread->stop(); 1851 _cm_thread->stop(); 1852 if (G1StringDedup::is_enabled()) { 1853 G1StringDedup::stop(); 1854 } 1855 } 1856 1857 void G1CollectedHeap::safepoint_synchronize_begin() { 1858 SuspendibleThreadSet::synchronize(); 1859 } 1860 1861 void G1CollectedHeap::safepoint_synchronize_end() { 1862 SuspendibleThreadSet::desynchronize(); 1863 } 1864 1865 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1866 return HeapRegion::max_region_size(); 1867 } 1868 1869 void G1CollectedHeap::post_initialize() { 1870 CollectedHeap::post_initialize(); 1871 ref_processing_init(); 1872 } 1873 1874 void G1CollectedHeap::ref_processing_init() { 1875 // Reference processing in G1 currently works as follows: 1876 // 1877 // * There are two reference processor instances. One is 1878 // used to record and process discovered references 1879 // during concurrent marking; the other is used to 1880 // record and process references during STW pauses 1881 // (both full and incremental). 1882 // * Both ref processors need to 'span' the entire heap as 1883 // the regions in the collection set may be dotted around. 1884 // 1885 // * For the concurrent marking ref processor: 1886 // * Reference discovery is enabled at initial marking. 1887 // * Reference discovery is disabled and the discovered 1888 // references processed etc during remarking. 1889 // * Reference discovery is MT (see below). 1890 // * Reference discovery requires a barrier (see below). 1891 // * Reference processing may or may not be MT 1892 // (depending on the value of ParallelRefProcEnabled 1893 // and ParallelGCThreads). 1894 // * A full GC disables reference discovery by the CM 1895 // ref processor and abandons any entries on it's 1896 // discovered lists. 1897 // 1898 // * For the STW processor: 1899 // * Non MT discovery is enabled at the start of a full GC. 1900 // * Processing and enqueueing during a full GC is non-MT. 1901 // * During a full GC, references are processed after marking. 1902 // 1903 // * Discovery (may or may not be MT) is enabled at the start 1904 // of an incremental evacuation pause. 1905 // * References are processed near the end of a STW evacuation pause. 1906 // * For both types of GC: 1907 // * Discovery is atomic - i.e. not concurrent. 1908 // * Reference discovery will not need a barrier. 1909 1910 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1911 1912 // Concurrent Mark ref processor 1913 _ref_processor_cm = 1914 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1915 mt_processing, // mt processing 1916 ParallelGCThreads, // degree of mt processing 1917 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1918 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1919 false, // Reference discovery is not atomic 1920 &_is_alive_closure_cm, // is alive closure 1921 true); // allow changes to number of processing threads 1922 1923 // STW ref processor 1924 _ref_processor_stw = 1925 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1926 mt_processing, // mt processing 1927 ParallelGCThreads, // degree of mt processing 1928 (ParallelGCThreads > 1), // mt discovery 1929 ParallelGCThreads, // degree of mt discovery 1930 true, // Reference discovery is atomic 1931 &_is_alive_closure_stw, // is alive closure 1932 true); // allow changes to number of processing threads 1933 } 1934 1935 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1936 return _collector_policy; 1937 } 1938 1939 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1940 return &_soft_ref_policy; 1941 } 1942 1943 size_t G1CollectedHeap::capacity() const { 1944 return _hrm->length() * HeapRegion::GrainBytes; 1945 } 1946 1947 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1948 return _hrm->total_free_bytes(); 1949 } 1950 1951 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1952 _hot_card_cache->drain(cl, worker_i); 1953 } 1954 1955 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1956 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1957 size_t n_completed_buffers = 0; 1958 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1959 n_completed_buffers++; 1960 } 1961 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!"); 1962 phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1963 } 1964 1965 // Computes the sum of the storage used by the various regions. 1966 size_t G1CollectedHeap::used() const { 1967 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1968 if (_archive_allocator != NULL) { 1969 result += _archive_allocator->used(); 1970 } 1971 return result; 1972 } 1973 1974 size_t G1CollectedHeap::used_unlocked() const { 1975 return _summary_bytes_used; 1976 } 1977 1978 class SumUsedClosure: public HeapRegionClosure { 1979 size_t _used; 1980 public: 1981 SumUsedClosure() : _used(0) {} 1982 bool do_heap_region(HeapRegion* r) { 1983 _used += r->used(); 1984 return false; 1985 } 1986 size_t result() { return _used; } 1987 }; 1988 1989 size_t G1CollectedHeap::recalculate_used() const { 1990 SumUsedClosure blk; 1991 heap_region_iterate(&blk); 1992 return blk.result(); 1993 } 1994 1995 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1996 switch (cause) { 1997 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1998 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1999 case GCCause::_wb_conc_mark: return true; 2000 default : return false; 2001 } 2002 } 2003 2004 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2005 switch (cause) { 2006 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2007 case GCCause::_g1_humongous_allocation: return true; 2008 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2009 default: return is_user_requested_concurrent_full_gc(cause); 2010 } 2011 } 2012 2013 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2014 if(policy()->force_upgrade_to_full()) { 2015 return true; 2016 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2017 return false; 2018 } else if (has_regions_left_for_allocation()) { 2019 return false; 2020 } else { 2021 return true; 2022 } 2023 } 2024 2025 #ifndef PRODUCT 2026 void G1CollectedHeap::allocate_dummy_regions() { 2027 // Let's fill up most of the region 2028 size_t word_size = HeapRegion::GrainWords - 1024; 2029 // And as a result the region we'll allocate will be humongous. 2030 guarantee(is_humongous(word_size), "sanity"); 2031 2032 // _filler_array_max_size is set to humongous object threshold 2033 // but temporarily change it to use CollectedHeap::fill_with_object(). 2034 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2035 2036 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2037 // Let's use the existing mechanism for the allocation 2038 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2039 if (dummy_obj != NULL) { 2040 MemRegion mr(dummy_obj, word_size); 2041 CollectedHeap::fill_with_object(mr); 2042 } else { 2043 // If we can't allocate once, we probably cannot allocate 2044 // again. Let's get out of the loop. 2045 break; 2046 } 2047 } 2048 } 2049 #endif // !PRODUCT 2050 2051 void G1CollectedHeap::increment_old_marking_cycles_started() { 2052 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2053 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2054 "Wrong marking cycle count (started: %d, completed: %d)", 2055 _old_marking_cycles_started, _old_marking_cycles_completed); 2056 2057 _old_marking_cycles_started++; 2058 } 2059 2060 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2061 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2062 2063 // We assume that if concurrent == true, then the caller is a 2064 // concurrent thread that was joined the Suspendible Thread 2065 // Set. If there's ever a cheap way to check this, we should add an 2066 // assert here. 2067 2068 // Given that this method is called at the end of a Full GC or of a 2069 // concurrent cycle, and those can be nested (i.e., a Full GC can 2070 // interrupt a concurrent cycle), the number of full collections 2071 // completed should be either one (in the case where there was no 2072 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2073 // behind the number of full collections started. 2074 2075 // This is the case for the inner caller, i.e. a Full GC. 2076 assert(concurrent || 2077 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2078 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2079 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2080 "is inconsistent with _old_marking_cycles_completed = %u", 2081 _old_marking_cycles_started, _old_marking_cycles_completed); 2082 2083 // This is the case for the outer caller, i.e. the concurrent cycle. 2084 assert(!concurrent || 2085 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2086 "for outer caller (concurrent cycle): " 2087 "_old_marking_cycles_started = %u " 2088 "is inconsistent with _old_marking_cycles_completed = %u", 2089 _old_marking_cycles_started, _old_marking_cycles_completed); 2090 2091 _old_marking_cycles_completed += 1; 2092 2093 // We need to clear the "in_progress" flag in the CM thread before 2094 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2095 // is set) so that if a waiter requests another System.gc() it doesn't 2096 // incorrectly see that a marking cycle is still in progress. 2097 if (concurrent) { 2098 _cm_thread->set_idle(); 2099 } 2100 2101 // This notify_all() will ensure that a thread that called 2102 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2103 // and it's waiting for a full GC to finish will be woken up. It is 2104 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2105 FullGCCount_lock->notify_all(); 2106 } 2107 2108 void G1CollectedHeap::collect(GCCause::Cause cause) { 2109 try_collect(cause, true); 2110 } 2111 2112 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) { 2113 assert_heap_not_locked(); 2114 2115 bool gc_succeeded; 2116 bool should_retry_gc; 2117 2118 do { 2119 should_retry_gc = false; 2120 2121 uint gc_count_before; 2122 uint old_marking_count_before; 2123 uint full_gc_count_before; 2124 2125 { 2126 MutexLocker ml(Heap_lock); 2127 2128 // Read the GC count while holding the Heap_lock 2129 gc_count_before = total_collections(); 2130 full_gc_count_before = total_full_collections(); 2131 old_marking_count_before = _old_marking_cycles_started; 2132 } 2133 2134 if (should_do_concurrent_full_gc(cause)) { 2135 // Schedule an initial-mark evacuation pause that will start a 2136 // concurrent cycle. We're setting word_size to 0 which means that 2137 // we are not requesting a post-GC allocation. 2138 VM_G1CollectForAllocation op(0, /* word_size */ 2139 gc_count_before, 2140 cause, 2141 true, /* should_initiate_conc_mark */ 2142 policy()->max_pause_time_ms()); 2143 VMThread::execute(&op); 2144 gc_succeeded = op.gc_succeeded(); 2145 if (!gc_succeeded && retry_on_gc_failure) { 2146 if (old_marking_count_before == _old_marking_cycles_started) { 2147 should_retry_gc = op.should_retry_gc(); 2148 } else { 2149 // A Full GC happened while we were trying to schedule the 2150 // concurrent cycle. No point in starting a new cycle given 2151 // that the whole heap was collected anyway. 2152 } 2153 2154 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) { 2155 GCLocker::stall_until_clear(); 2156 } 2157 } 2158 } else { 2159 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2160 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2161 2162 // Schedule a standard evacuation pause. We're setting word_size 2163 // to 0 which means that we are not requesting a post-GC allocation. 2164 VM_G1CollectForAllocation op(0, /* word_size */ 2165 gc_count_before, 2166 cause, 2167 false, /* should_initiate_conc_mark */ 2168 policy()->max_pause_time_ms()); 2169 VMThread::execute(&op); 2170 gc_succeeded = op.gc_succeeded(); 2171 } else { 2172 // Schedule a Full GC. 2173 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2174 VMThread::execute(&op); 2175 gc_succeeded = op.gc_succeeded(); 2176 } 2177 } 2178 } while (should_retry_gc); 2179 return gc_succeeded; 2180 } 2181 2182 bool G1CollectedHeap::is_in(const void* p) const { 2183 if (_hrm->reserved().contains(p)) { 2184 // Given that we know that p is in the reserved space, 2185 // heap_region_containing() should successfully 2186 // return the containing region. 2187 HeapRegion* hr = heap_region_containing(p); 2188 return hr->is_in(p); 2189 } else { 2190 return false; 2191 } 2192 } 2193 2194 #ifdef ASSERT 2195 bool G1CollectedHeap::is_in_exact(const void* p) const { 2196 bool contains = reserved_region().contains(p); 2197 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2198 if (contains && available) { 2199 return true; 2200 } else { 2201 return false; 2202 } 2203 } 2204 #endif 2205 2206 // Iteration functions. 2207 2208 // Iterates an ObjectClosure over all objects within a HeapRegion. 2209 2210 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2211 ObjectClosure* _cl; 2212 public: 2213 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2214 bool do_heap_region(HeapRegion* r) { 2215 if (!r->is_continues_humongous()) { 2216 r->object_iterate(_cl); 2217 } 2218 return false; 2219 } 2220 }; 2221 2222 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2223 IterateObjectClosureRegionClosure blk(cl); 2224 heap_region_iterate(&blk); 2225 } 2226 2227 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2228 _hrm->iterate(cl); 2229 } 2230 2231 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2232 HeapRegionClaimer *hrclaimer, 2233 uint worker_id) const { 2234 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2235 } 2236 2237 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2238 HeapRegionClaimer *hrclaimer) const { 2239 _hrm->par_iterate(cl, hrclaimer, 0); 2240 } 2241 2242 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2243 _collection_set.iterate(cl); 2244 } 2245 2246 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2247 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2248 } 2249 2250 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2251 HeapRegion* hr = heap_region_containing(addr); 2252 return hr->block_start(addr); 2253 } 2254 2255 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2256 HeapRegion* hr = heap_region_containing(addr); 2257 return hr->block_is_obj(addr); 2258 } 2259 2260 bool G1CollectedHeap::supports_tlab_allocation() const { 2261 return true; 2262 } 2263 2264 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2265 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2266 } 2267 2268 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2269 return _eden.length() * HeapRegion::GrainBytes; 2270 } 2271 2272 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2273 // must be equal to the humongous object limit. 2274 size_t G1CollectedHeap::max_tlab_size() const { 2275 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2276 } 2277 2278 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2279 return _allocator->unsafe_max_tlab_alloc(); 2280 } 2281 2282 size_t G1CollectedHeap::max_capacity() const { 2283 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2284 } 2285 2286 size_t G1CollectedHeap::max_reserved_capacity() const { 2287 return _hrm->max_length() * HeapRegion::GrainBytes; 2288 } 2289 2290 jlong G1CollectedHeap::millis_since_last_gc() { 2291 // See the notes in GenCollectedHeap::millis_since_last_gc() 2292 // for more information about the implementation. 2293 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2294 _policy->collection_pause_end_millis(); 2295 if (ret_val < 0) { 2296 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2297 ". returning zero instead.", ret_val); 2298 return 0; 2299 } 2300 return ret_val; 2301 } 2302 2303 void G1CollectedHeap::deduplicate_string(oop str) { 2304 assert(java_lang_String::is_instance(str), "invariant"); 2305 2306 if (G1StringDedup::is_enabled()) { 2307 G1StringDedup::deduplicate(str); 2308 } 2309 } 2310 2311 void G1CollectedHeap::prepare_for_verify() { 2312 _verifier->prepare_for_verify(); 2313 } 2314 2315 void G1CollectedHeap::verify(VerifyOption vo) { 2316 _verifier->verify(vo); 2317 } 2318 2319 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2320 return true; 2321 } 2322 2323 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2324 return _cm_thread->request_concurrent_phase(phase); 2325 } 2326 2327 bool G1CollectedHeap::is_heterogeneous_heap() const { 2328 return _collector_policy->is_heterogeneous_heap(); 2329 } 2330 2331 class PrintRegionClosure: public HeapRegionClosure { 2332 outputStream* _st; 2333 public: 2334 PrintRegionClosure(outputStream* st) : _st(st) {} 2335 bool do_heap_region(HeapRegion* r) { 2336 r->print_on(_st); 2337 return false; 2338 } 2339 }; 2340 2341 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2342 const HeapRegion* hr, 2343 const VerifyOption vo) const { 2344 switch (vo) { 2345 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2346 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2347 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2348 default: ShouldNotReachHere(); 2349 } 2350 return false; // keep some compilers happy 2351 } 2352 2353 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2354 const VerifyOption vo) const { 2355 switch (vo) { 2356 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2357 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2358 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2359 default: ShouldNotReachHere(); 2360 } 2361 return false; // keep some compilers happy 2362 } 2363 2364 void G1CollectedHeap::print_heap_regions() const { 2365 LogTarget(Trace, gc, heap, region) lt; 2366 if (lt.is_enabled()) { 2367 LogStream ls(lt); 2368 print_regions_on(&ls); 2369 } 2370 } 2371 2372 void G1CollectedHeap::print_on(outputStream* st) const { 2373 st->print(" %-20s", "garbage-first heap"); 2374 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2375 capacity()/K, used_unlocked()/K); 2376 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2377 p2i(_hrm->reserved().start()), 2378 p2i(_hrm->reserved().end())); 2379 st->cr(); 2380 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2381 uint young_regions = young_regions_count(); 2382 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2383 (size_t) young_regions * HeapRegion::GrainBytes / K); 2384 uint survivor_regions = survivor_regions_count(); 2385 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2386 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2387 st->cr(); 2388 MetaspaceUtils::print_on(st); 2389 } 2390 2391 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2392 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2393 "HS=humongous(starts), HC=humongous(continues), " 2394 "CS=collection set, F=free, A=archive, " 2395 "TAMS=top-at-mark-start (previous, next)"); 2396 PrintRegionClosure blk(st); 2397 heap_region_iterate(&blk); 2398 } 2399 2400 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2401 print_on(st); 2402 2403 // Print the per-region information. 2404 print_regions_on(st); 2405 } 2406 2407 void G1CollectedHeap::print_on_error(outputStream* st) const { 2408 this->CollectedHeap::print_on_error(st); 2409 2410 if (_cm != NULL) { 2411 st->cr(); 2412 _cm->print_on_error(st); 2413 } 2414 } 2415 2416 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2417 workers()->print_worker_threads_on(st); 2418 _cm_thread->print_on(st); 2419 st->cr(); 2420 _cm->print_worker_threads_on(st); 2421 _cr->print_threads_on(st); 2422 _young_gen_sampling_thread->print_on(st); 2423 if (G1StringDedup::is_enabled()) { 2424 G1StringDedup::print_worker_threads_on(st); 2425 } 2426 } 2427 2428 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2429 workers()->threads_do(tc); 2430 tc->do_thread(_cm_thread); 2431 _cm->threads_do(tc); 2432 _cr->threads_do(tc); 2433 tc->do_thread(_young_gen_sampling_thread); 2434 if (G1StringDedup::is_enabled()) { 2435 G1StringDedup::threads_do(tc); 2436 } 2437 } 2438 2439 void G1CollectedHeap::print_tracing_info() const { 2440 rem_set()->print_summary_info(); 2441 concurrent_mark()->print_summary_info(); 2442 } 2443 2444 #ifndef PRODUCT 2445 // Helpful for debugging RSet issues. 2446 2447 class PrintRSetsClosure : public HeapRegionClosure { 2448 private: 2449 const char* _msg; 2450 size_t _occupied_sum; 2451 2452 public: 2453 bool do_heap_region(HeapRegion* r) { 2454 HeapRegionRemSet* hrrs = r->rem_set(); 2455 size_t occupied = hrrs->occupied(); 2456 _occupied_sum += occupied; 2457 2458 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2459 if (occupied == 0) { 2460 tty->print_cr(" RSet is empty"); 2461 } else { 2462 hrrs->print(); 2463 } 2464 tty->print_cr("----------"); 2465 return false; 2466 } 2467 2468 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2469 tty->cr(); 2470 tty->print_cr("========================================"); 2471 tty->print_cr("%s", msg); 2472 tty->cr(); 2473 } 2474 2475 ~PrintRSetsClosure() { 2476 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2477 tty->print_cr("========================================"); 2478 tty->cr(); 2479 } 2480 }; 2481 2482 void G1CollectedHeap::print_cset_rsets() { 2483 PrintRSetsClosure cl("Printing CSet RSets"); 2484 collection_set_iterate(&cl); 2485 } 2486 2487 void G1CollectedHeap::print_all_rsets() { 2488 PrintRSetsClosure cl("Printing All RSets");; 2489 heap_region_iterate(&cl); 2490 } 2491 #endif // PRODUCT 2492 2493 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2494 2495 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2496 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2497 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2498 2499 size_t eden_capacity_bytes = 2500 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2501 2502 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2503 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2504 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2505 } 2506 2507 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2508 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2509 stats->unused(), stats->used(), stats->region_end_waste(), 2510 stats->regions_filled(), stats->direct_allocated(), 2511 stats->failure_used(), stats->failure_waste()); 2512 } 2513 2514 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2515 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2516 gc_tracer->report_gc_heap_summary(when, heap_summary); 2517 2518 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2519 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2520 } 2521 2522 G1CollectedHeap* G1CollectedHeap::heap() { 2523 CollectedHeap* heap = Universe::heap(); 2524 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2525 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2526 return (G1CollectedHeap*)heap; 2527 } 2528 2529 void G1CollectedHeap::gc_prologue(bool full) { 2530 // always_do_update_barrier = false; 2531 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2532 2533 // This summary needs to be printed before incrementing total collections. 2534 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2535 2536 // Update common counters. 2537 increment_total_collections(full /* full gc */); 2538 if (full || collector_state()->in_initial_mark_gc()) { 2539 increment_old_marking_cycles_started(); 2540 } 2541 2542 // Fill TLAB's and such 2543 double start = os::elapsedTime(); 2544 ensure_parsability(true); 2545 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2546 } 2547 2548 void G1CollectedHeap::gc_epilogue(bool full) { 2549 // Update common counters. 2550 if (full) { 2551 // Update the number of full collections that have been completed. 2552 increment_old_marking_cycles_completed(false /* concurrent */); 2553 } 2554 2555 // We are at the end of the GC. Total collections has already been increased. 2556 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2557 2558 // FIXME: what is this about? 2559 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2560 // is set. 2561 #if COMPILER2_OR_JVMCI 2562 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2563 #endif 2564 // always_do_update_barrier = true; 2565 2566 double start = os::elapsedTime(); 2567 resize_all_tlabs(); 2568 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2569 2570 MemoryService::track_memory_usage(); 2571 // We have just completed a GC. Update the soft reference 2572 // policy with the new heap occupancy 2573 Universe::update_heap_info_at_gc(); 2574 } 2575 2576 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2577 uint gc_count_before, 2578 bool* succeeded, 2579 GCCause::Cause gc_cause) { 2580 assert_heap_not_locked_and_not_at_safepoint(); 2581 VM_G1CollectForAllocation op(word_size, 2582 gc_count_before, 2583 gc_cause, 2584 false, /* should_initiate_conc_mark */ 2585 policy()->max_pause_time_ms()); 2586 VMThread::execute(&op); 2587 2588 HeapWord* result = op.result(); 2589 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded(); 2590 assert(result == NULL || ret_succeeded, 2591 "the result should be NULL if the VM did not succeed"); 2592 *succeeded = ret_succeeded; 2593 2594 assert_heap_not_locked(); 2595 return result; 2596 } 2597 2598 void G1CollectedHeap::do_concurrent_mark() { 2599 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2600 if (!_cm_thread->in_progress()) { 2601 _cm_thread->set_started(); 2602 CGC_lock->notify(); 2603 } 2604 } 2605 2606 size_t G1CollectedHeap::pending_card_num() { 2607 struct CountCardsClosure : public ThreadClosure { 2608 size_t _cards; 2609 CountCardsClosure() : _cards(0) {} 2610 virtual void do_thread(Thread* t) { 2611 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2612 } 2613 } count_from_threads; 2614 Threads::threads_do(&count_from_threads); 2615 2616 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2617 size_t buffer_size = dcqs.buffer_size(); 2618 size_t buffer_num = dcqs.completed_buffers_num(); 2619 2620 return buffer_size * buffer_num + count_from_threads._cards; 2621 } 2622 2623 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2624 // We don't nominate objects with many remembered set entries, on 2625 // the assumption that such objects are likely still live. 2626 HeapRegionRemSet* rem_set = r->rem_set(); 2627 2628 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2629 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2630 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2631 } 2632 2633 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2634 private: 2635 size_t _total_humongous; 2636 size_t _candidate_humongous; 2637 2638 G1DirtyCardQueue _dcq; 2639 2640 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2641 assert(region->is_starts_humongous(), "Must start a humongous object"); 2642 2643 oop obj = oop(region->bottom()); 2644 2645 // Dead objects cannot be eager reclaim candidates. Due to class 2646 // unloading it is unsafe to query their classes so we return early. 2647 if (g1h->is_obj_dead(obj, region)) { 2648 return false; 2649 } 2650 2651 // If we do not have a complete remembered set for the region, then we can 2652 // not be sure that we have all references to it. 2653 if (!region->rem_set()->is_complete()) { 2654 return false; 2655 } 2656 // Candidate selection must satisfy the following constraints 2657 // while concurrent marking is in progress: 2658 // 2659 // * In order to maintain SATB invariants, an object must not be 2660 // reclaimed if it was allocated before the start of marking and 2661 // has not had its references scanned. Such an object must have 2662 // its references (including type metadata) scanned to ensure no 2663 // live objects are missed by the marking process. Objects 2664 // allocated after the start of concurrent marking don't need to 2665 // be scanned. 2666 // 2667 // * An object must not be reclaimed if it is on the concurrent 2668 // mark stack. Objects allocated after the start of concurrent 2669 // marking are never pushed on the mark stack. 2670 // 2671 // Nominating only objects allocated after the start of concurrent 2672 // marking is sufficient to meet both constraints. This may miss 2673 // some objects that satisfy the constraints, but the marking data 2674 // structures don't support efficiently performing the needed 2675 // additional tests or scrubbing of the mark stack. 2676 // 2677 // However, we presently only nominate is_typeArray() objects. 2678 // A humongous object containing references induces remembered 2679 // set entries on other regions. In order to reclaim such an 2680 // object, those remembered sets would need to be cleaned up. 2681 // 2682 // We also treat is_typeArray() objects specially, allowing them 2683 // to be reclaimed even if allocated before the start of 2684 // concurrent mark. For this we rely on mark stack insertion to 2685 // exclude is_typeArray() objects, preventing reclaiming an object 2686 // that is in the mark stack. We also rely on the metadata for 2687 // such objects to be built-in and so ensured to be kept live. 2688 // Frequent allocation and drop of large binary blobs is an 2689 // important use case for eager reclaim, and this special handling 2690 // may reduce needed headroom. 2691 2692 return obj->is_typeArray() && 2693 g1h->is_potential_eager_reclaim_candidate(region); 2694 } 2695 2696 public: 2697 RegisterHumongousWithInCSetFastTestClosure() 2698 : _total_humongous(0), 2699 _candidate_humongous(0), 2700 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2701 } 2702 2703 virtual bool do_heap_region(HeapRegion* r) { 2704 if (!r->is_starts_humongous()) { 2705 return false; 2706 } 2707 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2708 2709 bool is_candidate = humongous_region_is_candidate(g1h, r); 2710 uint rindex = r->hrm_index(); 2711 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2712 if (is_candidate) { 2713 _candidate_humongous++; 2714 g1h->register_humongous_region_with_cset(rindex); 2715 // Is_candidate already filters out humongous object with large remembered sets. 2716 // If we have a humongous object with a few remembered sets, we simply flush these 2717 // remembered set entries into the DCQS. That will result in automatic 2718 // re-evaluation of their remembered set entries during the following evacuation 2719 // phase. 2720 if (!r->rem_set()->is_empty()) { 2721 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2722 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2723 G1CardTable* ct = g1h->card_table(); 2724 HeapRegionRemSetIterator hrrs(r->rem_set()); 2725 size_t card_index; 2726 while (hrrs.has_next(card_index)) { 2727 CardTable::CardValue* card_ptr = ct->byte_for_index(card_index); 2728 // The remembered set might contain references to already freed 2729 // regions. Filter out such entries to avoid failing card table 2730 // verification. 2731 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2732 if (*card_ptr != G1CardTable::dirty_card_val()) { 2733 *card_ptr = G1CardTable::dirty_card_val(); 2734 _dcq.enqueue(card_ptr); 2735 } 2736 } 2737 } 2738 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2739 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2740 hrrs.n_yielded(), r->rem_set()->occupied()); 2741 // We should only clear the card based remembered set here as we will not 2742 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2743 // (and probably never) we do not enter this path if there are other kind of 2744 // remembered sets for this region. 2745 r->rem_set()->clear_locked(true /* only_cardset */); 2746 // Clear_locked() above sets the state to Empty. However we want to continue 2747 // collecting remembered set entries for humongous regions that were not 2748 // reclaimed. 2749 r->rem_set()->set_state_complete(); 2750 } 2751 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2752 } 2753 _total_humongous++; 2754 2755 return false; 2756 } 2757 2758 size_t total_humongous() const { return _total_humongous; } 2759 size_t candidate_humongous() const { return _candidate_humongous; } 2760 2761 void flush_rem_set_entries() { _dcq.flush(); } 2762 }; 2763 2764 void G1CollectedHeap::register_humongous_regions_with_cset() { 2765 if (!G1EagerReclaimHumongousObjects) { 2766 phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2767 return; 2768 } 2769 double time = os::elapsed_counter(); 2770 2771 // Collect reclaim candidate information and register candidates with cset. 2772 RegisterHumongousWithInCSetFastTestClosure cl; 2773 heap_region_iterate(&cl); 2774 2775 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2776 phase_times()->record_fast_reclaim_humongous_stats(time, 2777 cl.total_humongous(), 2778 cl.candidate_humongous()); 2779 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2780 2781 // Finally flush all remembered set entries to re-check into the global DCQS. 2782 cl.flush_rem_set_entries(); 2783 } 2784 2785 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2786 public: 2787 bool do_heap_region(HeapRegion* hr) { 2788 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2789 hr->verify_rem_set(); 2790 } 2791 return false; 2792 } 2793 }; 2794 2795 uint G1CollectedHeap::num_task_queues() const { 2796 return _task_queues->size(); 2797 } 2798 2799 #if TASKQUEUE_STATS 2800 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2801 st->print_raw_cr("GC Task Stats"); 2802 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2803 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2804 } 2805 2806 void G1CollectedHeap::print_taskqueue_stats() const { 2807 if (!log_is_enabled(Trace, gc, task, stats)) { 2808 return; 2809 } 2810 Log(gc, task, stats) log; 2811 ResourceMark rm; 2812 LogStream ls(log.trace()); 2813 outputStream* st = &ls; 2814 2815 print_taskqueue_stats_hdr(st); 2816 2817 TaskQueueStats totals; 2818 const uint n = num_task_queues(); 2819 for (uint i = 0; i < n; ++i) { 2820 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2821 totals += task_queue(i)->stats; 2822 } 2823 st->print_raw("tot "); totals.print(st); st->cr(); 2824 2825 DEBUG_ONLY(totals.verify()); 2826 } 2827 2828 void G1CollectedHeap::reset_taskqueue_stats() { 2829 const uint n = num_task_queues(); 2830 for (uint i = 0; i < n; ++i) { 2831 task_queue(i)->stats.reset(); 2832 } 2833 } 2834 #endif // TASKQUEUE_STATS 2835 2836 void G1CollectedHeap::wait_for_root_region_scanning() { 2837 double scan_wait_start = os::elapsedTime(); 2838 // We have to wait until the CM threads finish scanning the 2839 // root regions as it's the only way to ensure that all the 2840 // objects on them have been correctly scanned before we start 2841 // moving them during the GC. 2842 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2843 double wait_time_ms = 0.0; 2844 if (waited) { 2845 double scan_wait_end = os::elapsedTime(); 2846 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2847 } 2848 phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2849 } 2850 2851 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2852 private: 2853 G1HRPrinter* _hr_printer; 2854 public: 2855 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2856 2857 virtual bool do_heap_region(HeapRegion* r) { 2858 _hr_printer->cset(r); 2859 return false; 2860 } 2861 }; 2862 2863 void G1CollectedHeap::start_new_collection_set() { 2864 double start = os::elapsedTime(); 2865 2866 collection_set()->start_incremental_building(); 2867 2868 clear_cset_fast_test(); 2869 2870 guarantee(_eden.length() == 0, "eden should have been cleared"); 2871 policy()->transfer_survivors_to_cset(survivor()); 2872 2873 // We redo the verification but now wrt to the new CSet which 2874 // has just got initialized after the previous CSet was freed. 2875 _cm->verify_no_collection_set_oops(); 2876 2877 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2878 } 2879 2880 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms){ 2881 policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2882 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2883 2884 _cm->verify_no_collection_set_oops(); 2885 2886 if (_hr_printer.is_active()) { 2887 G1PrintCollectionSetClosure cl(&_hr_printer); 2888 _collection_set.iterate(&cl); 2889 } 2890 } 2891 2892 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const { 2893 if (collector_state()->in_initial_mark_gc()) { 2894 return G1HeapVerifier::G1VerifyConcurrentStart; 2895 } else if (collector_state()->in_young_only_phase()) { 2896 return G1HeapVerifier::G1VerifyYoungNormal; 2897 } else { 2898 return G1HeapVerifier::G1VerifyMixed; 2899 } 2900 } 2901 2902 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) { 2903 if (VerifyRememberedSets) { 2904 log_info(gc, verify)("[Verifying RemSets before GC]"); 2905 VerifyRegionRemSetClosure v_cl; 2906 heap_region_iterate(&v_cl); 2907 } 2908 _verifier->verify_before_gc(type); 2909 _verifier->check_bitmaps("GC Start"); 2910 } 2911 2912 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) { 2913 if (VerifyRememberedSets) { 2914 log_info(gc, verify)("[Verifying RemSets after GC]"); 2915 VerifyRegionRemSetClosure v_cl; 2916 heap_region_iterate(&v_cl); 2917 } 2918 _verifier->verify_after_gc(type); 2919 _verifier->check_bitmaps("GC End"); 2920 } 2921 2922 void G1CollectedHeap::expand_heap_after_young_collection(){ 2923 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2924 if (expand_bytes > 0) { 2925 // No need for an ergo logging here, 2926 // expansion_amount() does this when it returns a value > 0. 2927 double expand_ms; 2928 if (!expand(expand_bytes, _workers, &expand_ms)) { 2929 // We failed to expand the heap. Cannot do anything about it. 2930 } 2931 phase_times()->record_expand_heap_time(expand_ms); 2932 } 2933 } 2934 2935 const char* G1CollectedHeap::young_gc_name() const { 2936 if (collector_state()->in_initial_mark_gc()) { 2937 return "Pause Young (Concurrent Start)"; 2938 } else if (collector_state()->in_young_only_phase()) { 2939 if (collector_state()->in_young_gc_before_mixed()) { 2940 return "Pause Young (Prepare Mixed)"; 2941 } else { 2942 return "Pause Young (Normal)"; 2943 } 2944 } else { 2945 return "Pause Young (Mixed)"; 2946 } 2947 } 2948 2949 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2950 assert_at_safepoint_on_vm_thread(); 2951 guarantee(!is_gc_active(), "collection is not reentrant"); 2952 2953 if (GCLocker::check_active_before_gc()) { 2954 return false; 2955 } 2956 2957 GCIdMark gc_id_mark; 2958 2959 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2960 ResourceMark rm; 2961 2962 policy()->note_gc_start(); 2963 2964 _gc_timer_stw->register_gc_start(); 2965 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2966 2967 wait_for_root_region_scanning(); 2968 2969 print_heap_before_gc(); 2970 print_heap_regions(); 2971 trace_heap_before_gc(_gc_tracer_stw); 2972 2973 _verifier->verify_region_sets_optional(); 2974 _verifier->verify_dirty_young_regions(); 2975 2976 // We should not be doing initial mark unless the conc mark thread is running 2977 if (!_cm_thread->should_terminate()) { 2978 // This call will decide whether this pause is an initial-mark 2979 // pause. If it is, in_initial_mark_gc() will return true 2980 // for the duration of this pause. 2981 policy()->decide_on_conc_mark_initiation(); 2982 } 2983 2984 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2985 assert(!collector_state()->in_initial_mark_gc() || 2986 collector_state()->in_young_only_phase(), "sanity"); 2987 // We also do not allow mixed GCs during marking. 2988 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2989 2990 // Record whether this pause is an initial mark. When the current 2991 // thread has completed its logging output and it's safe to signal 2992 // the CM thread, the flag's value in the policy has been reset. 2993 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2994 if (should_start_conc_mark) { 2995 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2996 } 2997 2998 // Inner scope for scope based logging, timers, and stats collection 2999 { 3000 G1EvacuationInfo evacuation_info; 3001 3002 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 3003 3004 GCTraceCPUTime tcpu; 3005 3006 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true); 3007 3008 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 3009 workers()->active_workers(), 3010 Threads::number_of_non_daemon_threads()); 3011 active_workers = workers()->update_active_workers(active_workers); 3012 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 3013 3014 G1MonitoringScope ms(g1mm(), 3015 false /* full_gc */, 3016 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 3017 3018 G1HeapTransition heap_transition(this); 3019 size_t heap_used_bytes_before_gc = used(); 3020 3021 { 3022 IsGCActiveMark x; 3023 3024 gc_prologue(false); 3025 3026 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type(); 3027 verify_before_young_collection(verify_type); 3028 3029 { 3030 // The elapsed time induced by the start time below deliberately elides 3031 // the possible verification above. 3032 double sample_start_time_sec = os::elapsedTime(); 3033 3034 // Please see comment in g1CollectedHeap.hpp and 3035 // G1CollectedHeap::ref_processing_init() to see how 3036 // reference processing currently works in G1. 3037 _ref_processor_stw->enable_discovery(); 3038 3039 // We want to temporarily turn off discovery by the 3040 // CM ref processor, if necessary, and turn it back on 3041 // on again later if we do. Using a scoped 3042 // NoRefDiscovery object will do this. 3043 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3044 3045 policy()->record_collection_pause_start(sample_start_time_sec); 3046 3047 // Forget the current allocation region (we might even choose it to be part 3048 // of the collection set!). 3049 _allocator->release_mutator_alloc_region(); 3050 3051 calculate_collection_set(evacuation_info, target_pause_time_ms); 3052 3053 G1ParScanThreadStateSet per_thread_states(this, 3054 workers()->active_workers(), 3055 collection_set()->young_region_length(), 3056 collection_set()->optional_region_length()); 3057 pre_evacuate_collection_set(evacuation_info); 3058 3059 // Actually do the work... 3060 evacuate_collection_set(&per_thread_states); 3061 evacuate_optional_collection_set(&per_thread_states); 3062 3063 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3064 3065 start_new_collection_set(); 3066 3067 _survivor_evac_stats.adjust_desired_plab_sz(); 3068 _old_evac_stats.adjust_desired_plab_sz(); 3069 3070 if (should_start_conc_mark) { 3071 // We have to do this before we notify the CM threads that 3072 // they can start working to make sure that all the 3073 // appropriate initialization is done on the CM object. 3074 concurrent_mark()->post_initial_mark(); 3075 // Note that we don't actually trigger the CM thread at 3076 // this point. We do that later when we're sure that 3077 // the current thread has completed its logging output. 3078 } 3079 3080 allocate_dummy_regions(); 3081 3082 _allocator->init_mutator_alloc_region(); 3083 3084 expand_heap_after_young_collection(); 3085 3086 double sample_end_time_sec = os::elapsedTime(); 3087 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3088 size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3089 policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3090 } 3091 3092 verify_after_young_collection(verify_type); 3093 3094 #ifdef TRACESPINNING 3095 ParallelTaskTerminator::print_termination_counts(); 3096 #endif 3097 3098 gc_epilogue(false); 3099 } 3100 3101 // Print the remainder of the GC log output. 3102 if (evacuation_failed()) { 3103 log_info(gc)("To-space exhausted"); 3104 } 3105 3106 policy()->print_phases(); 3107 heap_transition.print(); 3108 3109 _hrm->verify_optional(); 3110 _verifier->verify_region_sets_optional(); 3111 3112 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3113 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3114 3115 print_heap_after_gc(); 3116 print_heap_regions(); 3117 trace_heap_after_gc(_gc_tracer_stw); 3118 3119 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3120 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3121 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3122 // before any GC notifications are raised. 3123 g1mm()->update_sizes(); 3124 3125 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3126 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold()); 3127 _gc_timer_stw->register_gc_end(); 3128 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3129 } 3130 // It should now be safe to tell the concurrent mark thread to start 3131 // without its logging output interfering with the logging output 3132 // that came from the pause. 3133 3134 if (should_start_conc_mark) { 3135 // CAUTION: after the doConcurrentMark() call below, the concurrent marking 3136 // thread(s) could be running concurrently with us. Make sure that anything 3137 // after this point does not assume that we are the only GC thread running. 3138 // Note: of course, the actual marking work will not start until the safepoint 3139 // itself is released in SuspendibleThreadSet::desynchronize(). 3140 do_concurrent_mark(); 3141 } 3142 3143 return true; 3144 } 3145 3146 void G1CollectedHeap::remove_self_forwarding_pointers() { 3147 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3148 workers()->run_task(&rsfp_task); 3149 } 3150 3151 void G1CollectedHeap::restore_after_evac_failure() { 3152 double remove_self_forwards_start = os::elapsedTime(); 3153 3154 remove_self_forwarding_pointers(); 3155 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3156 _preserved_marks_set.restore(&task_executor); 3157 3158 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3159 } 3160 3161 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3162 if (!_evacuation_failed) { 3163 _evacuation_failed = true; 3164 } 3165 3166 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3167 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3168 } 3169 3170 bool G1ParEvacuateFollowersClosure::offer_termination() { 3171 EventGCPhaseParallel event; 3172 G1ParScanThreadState* const pss = par_scan_state(); 3173 start_term_time(); 3174 const bool res = terminator()->offer_termination(); 3175 end_term_time(); 3176 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3177 return res; 3178 } 3179 3180 void G1ParEvacuateFollowersClosure::do_void() { 3181 EventGCPhaseParallel event; 3182 G1ParScanThreadState* const pss = par_scan_state(); 3183 pss->trim_queue(); 3184 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3185 do { 3186 EventGCPhaseParallel event; 3187 pss->steal_and_trim_queue(queues()); 3188 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3189 } while (!offer_termination()); 3190 } 3191 3192 class G1ParTask : public AbstractGangTask { 3193 protected: 3194 G1CollectedHeap* _g1h; 3195 G1ParScanThreadStateSet* _pss; 3196 RefToScanQueueSet* _queues; 3197 G1RootProcessor* _root_processor; 3198 TaskTerminator _terminator; 3199 uint _n_workers; 3200 3201 public: 3202 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3203 : AbstractGangTask("G1 collection"), 3204 _g1h(g1h), 3205 _pss(per_thread_states), 3206 _queues(task_queues), 3207 _root_processor(root_processor), 3208 _terminator(n_workers, _queues), 3209 _n_workers(n_workers) 3210 {} 3211 3212 void work(uint worker_id) { 3213 if (worker_id >= _n_workers) return; // no work needed this round 3214 3215 double start_sec = os::elapsedTime(); 3216 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3217 3218 { 3219 ResourceMark rm; 3220 HandleMark hm; 3221 3222 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3223 3224 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3225 pss->set_ref_discoverer(rp); 3226 3227 double start_strong_roots_sec = os::elapsedTime(); 3228 3229 _root_processor->evacuate_roots(pss, worker_id); 3230 3231 _g1h->rem_set()->oops_into_collection_set_do(pss, worker_id); 3232 3233 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3234 3235 double term_sec = 0.0; 3236 size_t evac_term_attempts = 0; 3237 { 3238 double start = os::elapsedTime(); 3239 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy); 3240 evac.do_void(); 3241 3242 evac_term_attempts = evac.term_attempts(); 3243 term_sec = evac.term_time(); 3244 double elapsed_sec = os::elapsedTime() - start; 3245 3246 G1GCPhaseTimes* p = _g1h->phase_times(); 3247 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3248 3249 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy, 3250 worker_id, 3251 pss->lab_waste_words() * HeapWordSize, 3252 G1GCPhaseTimes::ObjCopyLABWaste); 3253 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy, 3254 worker_id, 3255 pss->lab_undo_waste_words() * HeapWordSize, 3256 G1GCPhaseTimes::ObjCopyLABUndoWaste); 3257 3258 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3259 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3260 } 3261 3262 assert(pss->queue_is_empty(), "should be empty"); 3263 3264 // Close the inner scope so that the ResourceMark and HandleMark 3265 // destructors are executed here and are included as part of the 3266 // "GC Worker Time". 3267 } 3268 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3269 } 3270 }; 3271 3272 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3273 bool class_unloading_occurred) { 3274 uint num_workers = workers()->active_workers(); 3275 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3276 workers()->run_task(&unlink_task); 3277 } 3278 3279 // Clean string dedup data structures. 3280 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3281 // record the durations of the phases. Hence the almost-copy. 3282 class G1StringDedupCleaningTask : public AbstractGangTask { 3283 BoolObjectClosure* _is_alive; 3284 OopClosure* _keep_alive; 3285 G1GCPhaseTimes* _phase_times; 3286 3287 public: 3288 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3289 OopClosure* keep_alive, 3290 G1GCPhaseTimes* phase_times) : 3291 AbstractGangTask("Partial Cleaning Task"), 3292 _is_alive(is_alive), 3293 _keep_alive(keep_alive), 3294 _phase_times(phase_times) 3295 { 3296 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3297 StringDedup::gc_prologue(true); 3298 } 3299 3300 ~G1StringDedupCleaningTask() { 3301 StringDedup::gc_epilogue(); 3302 } 3303 3304 void work(uint worker_id) { 3305 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3306 { 3307 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3308 StringDedupQueue::unlink_or_oops_do(&cl); 3309 } 3310 { 3311 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3312 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3313 } 3314 } 3315 }; 3316 3317 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3318 OopClosure* keep_alive, 3319 G1GCPhaseTimes* phase_times) { 3320 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3321 workers()->run_task(&cl); 3322 } 3323 3324 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3325 private: 3326 G1DirtyCardQueueSet* _queue; 3327 G1CollectedHeap* _g1h; 3328 public: 3329 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3330 _queue(queue), _g1h(g1h) { } 3331 3332 virtual void work(uint worker_id) { 3333 G1GCPhaseTimes* p = _g1h->phase_times(); 3334 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id); 3335 3336 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3337 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3338 3339 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3340 } 3341 }; 3342 3343 void G1CollectedHeap::redirty_logged_cards() { 3344 double redirty_logged_cards_start = os::elapsedTime(); 3345 3346 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3347 dirty_card_queue_set().reset_for_par_iteration(); 3348 workers()->run_task(&redirty_task); 3349 3350 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3351 dcq.merge_bufferlists(&dirty_card_queue_set()); 3352 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3353 3354 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3355 } 3356 3357 // Weak Reference Processing support 3358 3359 bool G1STWIsAliveClosure::do_object_b(oop p) { 3360 // An object is reachable if it is outside the collection set, 3361 // or is inside and copied. 3362 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3363 } 3364 3365 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3366 assert(obj != NULL, "must not be NULL"); 3367 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3368 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3369 // may falsely indicate that this is not the case here: however the collection set only 3370 // contains old regions when concurrent mark is not running. 3371 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3372 } 3373 3374 // Non Copying Keep Alive closure 3375 class G1KeepAliveClosure: public OopClosure { 3376 G1CollectedHeap*_g1h; 3377 public: 3378 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3379 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3380 void do_oop(oop* p) { 3381 oop obj = *p; 3382 assert(obj != NULL, "the caller should have filtered out NULL values"); 3383 3384 const InCSetState cset_state =_g1h->in_cset_state(obj); 3385 if (!cset_state.is_in_cset_or_humongous()) { 3386 return; 3387 } 3388 if (cset_state.is_in_cset()) { 3389 assert( obj->is_forwarded(), "invariant" ); 3390 *p = obj->forwardee(); 3391 } else { 3392 assert(!obj->is_forwarded(), "invariant" ); 3393 assert(cset_state.is_humongous(), 3394 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3395 _g1h->set_humongous_is_live(obj); 3396 } 3397 } 3398 }; 3399 3400 // Copying Keep Alive closure - can be called from both 3401 // serial and parallel code as long as different worker 3402 // threads utilize different G1ParScanThreadState instances 3403 // and different queues. 3404 3405 class G1CopyingKeepAliveClosure: public OopClosure { 3406 G1CollectedHeap* _g1h; 3407 G1ParScanThreadState* _par_scan_state; 3408 3409 public: 3410 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3411 G1ParScanThreadState* pss): 3412 _g1h(g1h), 3413 _par_scan_state(pss) 3414 {} 3415 3416 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3417 virtual void do_oop( oop* p) { do_oop_work(p); } 3418 3419 template <class T> void do_oop_work(T* p) { 3420 oop obj = RawAccess<>::oop_load(p); 3421 3422 if (_g1h->is_in_cset_or_humongous(obj)) { 3423 // If the referent object has been forwarded (either copied 3424 // to a new location or to itself in the event of an 3425 // evacuation failure) then we need to update the reference 3426 // field and, if both reference and referent are in the G1 3427 // heap, update the RSet for the referent. 3428 // 3429 // If the referent has not been forwarded then we have to keep 3430 // it alive by policy. Therefore we have copy the referent. 3431 // 3432 // When the queue is drained (after each phase of reference processing) 3433 // the object and it's followers will be copied, the reference field set 3434 // to point to the new location, and the RSet updated. 3435 _par_scan_state->push_on_queue(p); 3436 } 3437 } 3438 }; 3439 3440 // Serial drain queue closure. Called as the 'complete_gc' 3441 // closure for each discovered list in some of the 3442 // reference processing phases. 3443 3444 class G1STWDrainQueueClosure: public VoidClosure { 3445 protected: 3446 G1CollectedHeap* _g1h; 3447 G1ParScanThreadState* _par_scan_state; 3448 3449 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3450 3451 public: 3452 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3453 _g1h(g1h), 3454 _par_scan_state(pss) 3455 { } 3456 3457 void do_void() { 3458 G1ParScanThreadState* const pss = par_scan_state(); 3459 pss->trim_queue(); 3460 } 3461 }; 3462 3463 // Parallel Reference Processing closures 3464 3465 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3466 // processing during G1 evacuation pauses. 3467 3468 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3469 private: 3470 G1CollectedHeap* _g1h; 3471 G1ParScanThreadStateSet* _pss; 3472 RefToScanQueueSet* _queues; 3473 WorkGang* _workers; 3474 3475 public: 3476 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3477 G1ParScanThreadStateSet* per_thread_states, 3478 WorkGang* workers, 3479 RefToScanQueueSet *task_queues) : 3480 _g1h(g1h), 3481 _pss(per_thread_states), 3482 _queues(task_queues), 3483 _workers(workers) 3484 { 3485 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3486 } 3487 3488 // Executes the given task using concurrent marking worker threads. 3489 virtual void execute(ProcessTask& task, uint ergo_workers); 3490 }; 3491 3492 // Gang task for possibly parallel reference processing 3493 3494 class G1STWRefProcTaskProxy: public AbstractGangTask { 3495 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3496 ProcessTask& _proc_task; 3497 G1CollectedHeap* _g1h; 3498 G1ParScanThreadStateSet* _pss; 3499 RefToScanQueueSet* _task_queues; 3500 ParallelTaskTerminator* _terminator; 3501 3502 public: 3503 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3504 G1CollectedHeap* g1h, 3505 G1ParScanThreadStateSet* per_thread_states, 3506 RefToScanQueueSet *task_queues, 3507 ParallelTaskTerminator* terminator) : 3508 AbstractGangTask("Process reference objects in parallel"), 3509 _proc_task(proc_task), 3510 _g1h(g1h), 3511 _pss(per_thread_states), 3512 _task_queues(task_queues), 3513 _terminator(terminator) 3514 {} 3515 3516 virtual void work(uint worker_id) { 3517 // The reference processing task executed by a single worker. 3518 ResourceMark rm; 3519 HandleMark hm; 3520 3521 G1STWIsAliveClosure is_alive(_g1h); 3522 3523 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3524 pss->set_ref_discoverer(NULL); 3525 3526 // Keep alive closure. 3527 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3528 3529 // Complete GC closure 3530 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3531 3532 // Call the reference processing task's work routine. 3533 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3534 3535 // Note we cannot assert that the refs array is empty here as not all 3536 // of the processing tasks (specifically phase2 - pp2_work) execute 3537 // the complete_gc closure (which ordinarily would drain the queue) so 3538 // the queue may not be empty. 3539 } 3540 }; 3541 3542 // Driver routine for parallel reference processing. 3543 // Creates an instance of the ref processing gang 3544 // task and has the worker threads execute it. 3545 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3546 assert(_workers != NULL, "Need parallel worker threads."); 3547 3548 assert(_workers->active_workers() >= ergo_workers, 3549 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3550 ergo_workers, _workers->active_workers()); 3551 TaskTerminator terminator(ergo_workers, _queues); 3552 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3553 3554 _workers->run_task(&proc_task_proxy, ergo_workers); 3555 } 3556 3557 // End of weak reference support closures 3558 3559 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3560 double ref_proc_start = os::elapsedTime(); 3561 3562 ReferenceProcessor* rp = _ref_processor_stw; 3563 assert(rp->discovery_enabled(), "should have been enabled"); 3564 3565 // Closure to test whether a referent is alive. 3566 G1STWIsAliveClosure is_alive(this); 3567 3568 // Even when parallel reference processing is enabled, the processing 3569 // of JNI refs is serial and performed serially by the current thread 3570 // rather than by a worker. The following PSS will be used for processing 3571 // JNI refs. 3572 3573 // Use only a single queue for this PSS. 3574 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3575 pss->set_ref_discoverer(NULL); 3576 assert(pss->queue_is_empty(), "pre-condition"); 3577 3578 // Keep alive closure. 3579 G1CopyingKeepAliveClosure keep_alive(this, pss); 3580 3581 // Serial Complete GC closure 3582 G1STWDrainQueueClosure drain_queue(this, pss); 3583 3584 // Setup the soft refs policy... 3585 rp->setup_policy(false); 3586 3587 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times(); 3588 3589 ReferenceProcessorStats stats; 3590 if (!rp->processing_is_mt()) { 3591 // Serial reference processing... 3592 stats = rp->process_discovered_references(&is_alive, 3593 &keep_alive, 3594 &drain_queue, 3595 NULL, 3596 pt); 3597 } else { 3598 uint no_of_gc_workers = workers()->active_workers(); 3599 3600 // Parallel reference processing 3601 assert(no_of_gc_workers <= rp->max_num_queues(), 3602 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3603 no_of_gc_workers, rp->max_num_queues()); 3604 3605 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3606 stats = rp->process_discovered_references(&is_alive, 3607 &keep_alive, 3608 &drain_queue, 3609 &par_task_executor, 3610 pt); 3611 } 3612 3613 _gc_tracer_stw->report_gc_reference_stats(stats); 3614 3615 // We have completed copying any necessary live referent objects. 3616 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3617 3618 make_pending_list_reachable(); 3619 3620 assert(!rp->discovery_enabled(), "Postcondition"); 3621 rp->verify_no_references_recorded(); 3622 3623 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3624 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3625 } 3626 3627 void G1CollectedHeap::make_pending_list_reachable() { 3628 if (collector_state()->in_initial_mark_gc()) { 3629 oop pll_head = Universe::reference_pending_list(); 3630 if (pll_head != NULL) { 3631 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3632 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3633 } 3634 } 3635 } 3636 3637 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3638 double merge_pss_time_start = os::elapsedTime(); 3639 per_thread_states->flush(); 3640 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3641 } 3642 3643 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) { 3644 _expand_heap_after_alloc_failure = true; 3645 _evacuation_failed = false; 3646 3647 // Disable the hot card cache. 3648 _hot_card_cache->reset_hot_cache_claimed_index(); 3649 _hot_card_cache->set_use_cache(false); 3650 3651 // Initialize the GC alloc regions. 3652 _allocator->init_gc_alloc_regions(evacuation_info); 3653 3654 register_humongous_regions_with_cset(); 3655 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3656 3657 rem_set()->prepare_for_oops_into_collection_set_do(); 3658 _preserved_marks_set.assert_empty(); 3659 3660 #if COMPILER2_OR_JVMCI 3661 DerivedPointerTable::clear(); 3662 #endif 3663 3664 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3665 if (collector_state()->in_initial_mark_gc()) { 3666 concurrent_mark()->pre_initial_mark(); 3667 3668 double start_clear_claimed_marks = os::elapsedTime(); 3669 3670 ClassLoaderDataGraph::clear_claimed_marks(); 3671 3672 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3673 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3674 } 3675 } 3676 3677 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3678 // Should G1EvacuationFailureALot be in effect for this GC? 3679 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3680 3681 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3682 3683 double start_par_time_sec = os::elapsedTime(); 3684 double end_par_time_sec; 3685 3686 { 3687 const uint n_workers = workers()->active_workers(); 3688 G1RootProcessor root_processor(this, n_workers); 3689 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3690 3691 workers()->run_task(&g1_par_task); 3692 end_par_time_sec = os::elapsedTime(); 3693 3694 // Closing the inner scope will execute the destructor 3695 // for the G1RootProcessor object. We record the current 3696 // elapsed time before closing the scope so that time 3697 // taken for the destructor is NOT included in the 3698 // reported parallel time. 3699 } 3700 3701 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3702 phase_times()->record_par_time(par_time_ms); 3703 3704 double code_root_fixup_time_ms = 3705 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3706 phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms); 3707 } 3708 3709 class G1EvacuateOptionalRegionTask : public AbstractGangTask { 3710 G1CollectedHeap* _g1h; 3711 G1ParScanThreadStateSet* _per_thread_states; 3712 G1OptionalCSet* _optional; 3713 RefToScanQueueSet* _queues; 3714 ParallelTaskTerminator _terminator; 3715 3716 Tickspan trim_ticks(G1ParScanThreadState* pss) { 3717 Tickspan copy_time = pss->trim_ticks(); 3718 pss->reset_trim_ticks(); 3719 return copy_time; 3720 } 3721 3722 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3723 G1EvacuationRootClosures* root_cls = pss->closures(); 3724 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss); 3725 3726 size_t scanned = 0; 3727 size_t claimed = 0; 3728 size_t skipped = 0; 3729 size_t used_memory = 0; 3730 3731 Ticks start = Ticks::now(); 3732 Tickspan copy_time; 3733 3734 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) { 3735 HeapRegion* hr = _optional->region_at(i); 3736 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl); 3737 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops()); 3738 copy_time += trim_ticks(pss); 3739 3740 G1ScanRSForRegionClosure scan_rs_cl(_g1h->rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id); 3741 scan_rs_cl.do_heap_region(hr); 3742 copy_time += trim_ticks(pss); 3743 scanned += scan_rs_cl.cards_scanned(); 3744 claimed += scan_rs_cl.cards_claimed(); 3745 skipped += scan_rs_cl.cards_skipped(); 3746 3747 // Chunk lists for this region is no longer needed. 3748 used_memory += pss->oops_into_optional_region(hr)->used_memory(); 3749 } 3750 3751 Tickspan scan_time = (Ticks::now() - start) - copy_time; 3752 G1GCPhaseTimes* p = _g1h->phase_times(); 3753 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds()); 3754 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds()); 3755 3756 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards); 3757 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards); 3758 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards); 3759 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory); 3760 } 3761 3762 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3763 Ticks start = Ticks::now(); 3764 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy); 3765 cl.do_void(); 3766 3767 Tickspan evac_time = (Ticks::now() - start); 3768 G1GCPhaseTimes* p = _g1h->phase_times(); 3769 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds()); 3770 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation"); 3771 } 3772 3773 public: 3774 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h, 3775 G1ParScanThreadStateSet* per_thread_states, 3776 G1OptionalCSet* cset, 3777 RefToScanQueueSet* queues, 3778 uint n_workers) : 3779 AbstractGangTask("G1 Evacuation Optional Region Task"), 3780 _g1h(g1h), 3781 _per_thread_states(per_thread_states), 3782 _optional(cset), 3783 _queues(queues), 3784 _terminator(n_workers, _queues) { 3785 } 3786 3787 void work(uint worker_id) { 3788 ResourceMark rm; 3789 HandleMark hm; 3790 3791 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3792 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3793 3794 scan_roots(pss, worker_id); 3795 evacuate_live_objects(pss, worker_id); 3796 } 3797 }; 3798 3799 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) { 3800 class G1MarkScope : public MarkScope {}; 3801 G1MarkScope code_mark_scope; 3802 3803 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers()); 3804 workers()->run_task(&task); 3805 } 3806 3807 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3808 G1OptionalCSet optional_cset(&_collection_set, per_thread_states); 3809 if (optional_cset.is_empty()) { 3810 return; 3811 } 3812 3813 if (evacuation_failed()) { 3814 return; 3815 } 3816 3817 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0; 3818 3819 double start_time_sec = os::elapsedTime(); 3820 3821 do { 3822 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3823 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3824 3825 if (time_left_ms < 0) { 3826 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms); 3827 break; 3828 } 3829 3830 optional_cset.prepare_evacuation(time_left_ms * _policy->optional_evacuation_fraction()); 3831 if (optional_cset.prepare_failed()) { 3832 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms); 3833 break; 3834 } 3835 3836 evacuate_optional_regions(per_thread_states, &optional_cset); 3837 3838 optional_cset.complete_evacuation(); 3839 if (optional_cset.evacuation_failed()) { 3840 break; 3841 } 3842 } while (!optional_cset.is_empty()); 3843 3844 phase_times()->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0); 3845 } 3846 3847 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3848 // Also cleans the card table from temporary duplicate detection information used 3849 // during UpdateRS/ScanRS. 3850 rem_set()->cleanup_after_oops_into_collection_set_do(); 3851 3852 // Process any discovered reference objects - we have 3853 // to do this _before_ we retire the GC alloc regions 3854 // as we may have to copy some 'reachable' referent 3855 // objects (and their reachable sub-graphs) that were 3856 // not copied during the pause. 3857 process_discovered_references(per_thread_states); 3858 3859 G1STWIsAliveClosure is_alive(this); 3860 G1KeepAliveClosure keep_alive(this); 3861 3862 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3863 phase_times()->weak_phase_times()); 3864 3865 if (G1StringDedup::is_enabled()) { 3866 double string_dedup_time_ms = os::elapsedTime(); 3867 3868 string_dedup_cleaning(&is_alive, &keep_alive, phase_times()); 3869 3870 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3871 phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3872 } 3873 3874 _allocator->release_gc_alloc_regions(evacuation_info); 3875 3876 if (evacuation_failed()) { 3877 restore_after_evac_failure(); 3878 3879 // Reset the G1EvacuationFailureALot counters and flags 3880 NOT_PRODUCT(reset_evacuation_should_fail();) 3881 3882 double recalculate_used_start = os::elapsedTime(); 3883 set_used(recalculate_used()); 3884 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3885 3886 if (_archive_allocator != NULL) { 3887 _archive_allocator->clear_used(); 3888 } 3889 for (uint i = 0; i < ParallelGCThreads; i++) { 3890 if (_evacuation_failed_info_array[i].has_failed()) { 3891 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3892 } 3893 } 3894 } else { 3895 // The "used" of the the collection set have already been subtracted 3896 // when they were freed. Add in the bytes evacuated. 3897 increase_used(policy()->bytes_copied_during_gc()); 3898 } 3899 3900 _preserved_marks_set.assert_empty(); 3901 3902 merge_per_thread_state_info(per_thread_states); 3903 3904 // Reset and re-enable the hot card cache. 3905 // Note the counts for the cards in the regions in the 3906 // collection set are reset when the collection set is freed. 3907 _hot_card_cache->reset_hot_cache(); 3908 _hot_card_cache->set_use_cache(true); 3909 3910 purge_code_root_memory(); 3911 3912 redirty_logged_cards(); 3913 3914 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words()); 3915 3916 eagerly_reclaim_humongous_regions(); 3917 3918 record_obj_copy_mem_stats(); 3919 3920 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3921 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc()); 3922 3923 #if COMPILER2_OR_JVMCI 3924 double start = os::elapsedTime(); 3925 DerivedPointerTable::update_pointers(); 3926 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3927 #endif 3928 policy()->print_age_table(); 3929 } 3930 3931 void G1CollectedHeap::record_obj_copy_mem_stats() { 3932 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3933 3934 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3935 create_g1_evac_summary(&_old_evac_stats)); 3936 } 3937 3938 void G1CollectedHeap::free_region(HeapRegion* hr, 3939 FreeRegionList* free_list, 3940 bool skip_remset, 3941 bool skip_hot_card_cache, 3942 bool locked) { 3943 assert(!hr->is_free(), "the region should not be free"); 3944 assert(!hr->is_empty(), "the region should not be empty"); 3945 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3946 assert(free_list != NULL, "pre-condition"); 3947 3948 if (G1VerifyBitmaps) { 3949 MemRegion mr(hr->bottom(), hr->end()); 3950 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3951 } 3952 3953 // Clear the card counts for this region. 3954 // Note: we only need to do this if the region is not young 3955 // (since we don't refine cards in young regions). 3956 if (!skip_hot_card_cache && !hr->is_young()) { 3957 _hot_card_cache->reset_card_counts(hr); 3958 } 3959 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3960 _policy->remset_tracker()->update_at_free(hr); 3961 free_list->add_ordered(hr); 3962 } 3963 3964 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3965 FreeRegionList* free_list) { 3966 assert(hr->is_humongous(), "this is only for humongous regions"); 3967 assert(free_list != NULL, "pre-condition"); 3968 hr->clear_humongous(); 3969 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3970 } 3971 3972 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3973 const uint humongous_regions_removed) { 3974 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3975 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3976 _old_set.bulk_remove(old_regions_removed); 3977 _humongous_set.bulk_remove(humongous_regions_removed); 3978 } 3979 3980 } 3981 3982 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3983 assert(list != NULL, "list can't be null"); 3984 if (!list->is_empty()) { 3985 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3986 _hrm->insert_list_into_free_list(list); 3987 } 3988 } 3989 3990 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3991 decrease_used(bytes); 3992 } 3993 3994 class G1FreeCollectionSetTask : public AbstractGangTask { 3995 private: 3996 3997 // Closure applied to all regions in the collection set to do work that needs to 3998 // be done serially in a single thread. 3999 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4000 private: 4001 G1EvacuationInfo* _evacuation_info; 4002 const size_t* _surviving_young_words; 4003 4004 // Bytes used in successfully evacuated regions before the evacuation. 4005 size_t _before_used_bytes; 4006 // Bytes used in unsucessfully evacuated regions before the evacuation 4007 size_t _after_used_bytes; 4008 4009 size_t _bytes_allocated_in_old_since_last_gc; 4010 4011 size_t _failure_used_words; 4012 size_t _failure_waste_words; 4013 4014 FreeRegionList _local_free_list; 4015 public: 4016 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4017 HeapRegionClosure(), 4018 _evacuation_info(evacuation_info), 4019 _surviving_young_words(surviving_young_words), 4020 _before_used_bytes(0), 4021 _after_used_bytes(0), 4022 _bytes_allocated_in_old_since_last_gc(0), 4023 _failure_used_words(0), 4024 _failure_waste_words(0), 4025 _local_free_list("Local Region List for CSet Freeing") { 4026 } 4027 4028 virtual bool do_heap_region(HeapRegion* r) { 4029 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4030 4031 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4032 g1h->clear_in_cset(r); 4033 4034 if (r->is_young()) { 4035 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4036 "Young index %d is wrong for region %u of type %s with %u young regions", 4037 r->young_index_in_cset(), 4038 r->hrm_index(), 4039 r->get_type_str(), 4040 g1h->collection_set()->young_region_length()); 4041 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4042 r->record_surv_words_in_group(words_survived); 4043 } 4044 4045 if (!r->evacuation_failed()) { 4046 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4047 _before_used_bytes += r->used(); 4048 g1h->free_region(r, 4049 &_local_free_list, 4050 true, /* skip_remset */ 4051 true, /* skip_hot_card_cache */ 4052 true /* locked */); 4053 } else { 4054 r->uninstall_surv_rate_group(); 4055 r->set_young_index_in_cset(-1); 4056 r->set_evacuation_failed(false); 4057 // When moving a young gen region to old gen, we "allocate" that whole region 4058 // there. This is in addition to any already evacuated objects. Notify the 4059 // policy about that. 4060 // Old gen regions do not cause an additional allocation: both the objects 4061 // still in the region and the ones already moved are accounted for elsewhere. 4062 if (r->is_young()) { 4063 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4064 } 4065 // The region is now considered to be old. 4066 r->set_old(); 4067 // Do some allocation statistics accounting. Regions that failed evacuation 4068 // are always made old, so there is no need to update anything in the young 4069 // gen statistics, but we need to update old gen statistics. 4070 size_t used_words = r->marked_bytes() / HeapWordSize; 4071 4072 _failure_used_words += used_words; 4073 _failure_waste_words += HeapRegion::GrainWords - used_words; 4074 4075 g1h->old_set_add(r); 4076 _after_used_bytes += r->used(); 4077 } 4078 return false; 4079 } 4080 4081 void complete_work() { 4082 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4083 4084 _evacuation_info->set_regions_freed(_local_free_list.length()); 4085 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4086 4087 g1h->prepend_to_freelist(&_local_free_list); 4088 g1h->decrement_summary_bytes(_before_used_bytes); 4089 4090 G1Policy* policy = g1h->policy(); 4091 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4092 4093 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4094 } 4095 }; 4096 4097 G1CollectionSet* _collection_set; 4098 G1SerialFreeCollectionSetClosure _cl; 4099 const size_t* _surviving_young_words; 4100 4101 size_t _rs_lengths; 4102 4103 volatile jint _serial_work_claim; 4104 4105 struct WorkItem { 4106 uint region_idx; 4107 bool is_young; 4108 bool evacuation_failed; 4109 4110 WorkItem(HeapRegion* r) { 4111 region_idx = r->hrm_index(); 4112 is_young = r->is_young(); 4113 evacuation_failed = r->evacuation_failed(); 4114 } 4115 }; 4116 4117 volatile size_t _parallel_work_claim; 4118 size_t _num_work_items; 4119 WorkItem* _work_items; 4120 4121 void do_serial_work() { 4122 // Need to grab the lock to be allowed to modify the old region list. 4123 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4124 _collection_set->iterate(&_cl); 4125 } 4126 4127 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4128 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4129 4130 HeapRegion* r = g1h->region_at(region_idx); 4131 assert(!g1h->is_on_master_free_list(r), "sanity"); 4132 4133 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4134 4135 if (!is_young) { 4136 g1h->_hot_card_cache->reset_card_counts(r); 4137 } 4138 4139 if (!evacuation_failed) { 4140 r->rem_set()->clear_locked(); 4141 } 4142 } 4143 4144 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4145 private: 4146 size_t _cur_idx; 4147 WorkItem* _work_items; 4148 public: 4149 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4150 4151 virtual bool do_heap_region(HeapRegion* r) { 4152 _work_items[_cur_idx++] = WorkItem(r); 4153 return false; 4154 } 4155 }; 4156 4157 void prepare_work() { 4158 G1PrepareFreeCollectionSetClosure cl(_work_items); 4159 _collection_set->iterate(&cl); 4160 } 4161 4162 void complete_work() { 4163 _cl.complete_work(); 4164 4165 G1Policy* policy = G1CollectedHeap::heap()->policy(); 4166 policy->record_max_rs_lengths(_rs_lengths); 4167 policy->cset_regions_freed(); 4168 } 4169 public: 4170 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4171 AbstractGangTask("G1 Free Collection Set"), 4172 _collection_set(collection_set), 4173 _cl(evacuation_info, surviving_young_words), 4174 _surviving_young_words(surviving_young_words), 4175 _rs_lengths(0), 4176 _serial_work_claim(0), 4177 _parallel_work_claim(0), 4178 _num_work_items(collection_set->region_length()), 4179 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4180 prepare_work(); 4181 } 4182 4183 ~G1FreeCollectionSetTask() { 4184 complete_work(); 4185 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4186 } 4187 4188 // Chunk size for work distribution. The chosen value has been determined experimentally 4189 // to be a good tradeoff between overhead and achievable parallelism. 4190 static uint chunk_size() { return 32; } 4191 4192 virtual void work(uint worker_id) { 4193 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times(); 4194 4195 // Claim serial work. 4196 if (_serial_work_claim == 0) { 4197 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4198 if (value == 0) { 4199 double serial_time = os::elapsedTime(); 4200 do_serial_work(); 4201 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4202 } 4203 } 4204 4205 // Start parallel work. 4206 double young_time = 0.0; 4207 bool has_young_time = false; 4208 double non_young_time = 0.0; 4209 bool has_non_young_time = false; 4210 4211 while (true) { 4212 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4213 size_t cur = end - chunk_size(); 4214 4215 if (cur >= _num_work_items) { 4216 break; 4217 } 4218 4219 EventGCPhaseParallel event; 4220 double start_time = os::elapsedTime(); 4221 4222 end = MIN2(end, _num_work_items); 4223 4224 for (; cur < end; cur++) { 4225 bool is_young = _work_items[cur].is_young; 4226 4227 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4228 4229 double end_time = os::elapsedTime(); 4230 double time_taken = end_time - start_time; 4231 if (is_young) { 4232 young_time += time_taken; 4233 has_young_time = true; 4234 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4235 } else { 4236 non_young_time += time_taken; 4237 has_non_young_time = true; 4238 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4239 } 4240 start_time = end_time; 4241 } 4242 } 4243 4244 if (has_young_time) { 4245 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4246 } 4247 if (has_non_young_time) { 4248 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4249 } 4250 } 4251 }; 4252 4253 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4254 _eden.clear(); 4255 4256 double free_cset_start_time = os::elapsedTime(); 4257 4258 { 4259 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4260 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4261 4262 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4263 4264 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4265 cl.name(), 4266 num_workers, 4267 _collection_set.region_length()); 4268 workers()->run_task(&cl, num_workers); 4269 } 4270 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4271 4272 collection_set->clear(); 4273 } 4274 4275 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4276 private: 4277 FreeRegionList* _free_region_list; 4278 HeapRegionSet* _proxy_set; 4279 uint _humongous_objects_reclaimed; 4280 uint _humongous_regions_reclaimed; 4281 size_t _freed_bytes; 4282 public: 4283 4284 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4285 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4286 } 4287 4288 virtual bool do_heap_region(HeapRegion* r) { 4289 if (!r->is_starts_humongous()) { 4290 return false; 4291 } 4292 4293 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4294 4295 oop obj = (oop)r->bottom(); 4296 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4297 4298 // The following checks whether the humongous object is live are sufficient. 4299 // The main additional check (in addition to having a reference from the roots 4300 // or the young gen) is whether the humongous object has a remembered set entry. 4301 // 4302 // A humongous object cannot be live if there is no remembered set for it 4303 // because: 4304 // - there can be no references from within humongous starts regions referencing 4305 // the object because we never allocate other objects into them. 4306 // (I.e. there are no intra-region references that may be missed by the 4307 // remembered set) 4308 // - as soon there is a remembered set entry to the humongous starts region 4309 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4310 // until the end of a concurrent mark. 4311 // 4312 // It is not required to check whether the object has been found dead by marking 4313 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4314 // all objects allocated during that time are considered live. 4315 // SATB marking is even more conservative than the remembered set. 4316 // So if at this point in the collection there is no remembered set entry, 4317 // nobody has a reference to it. 4318 // At the start of collection we flush all refinement logs, and remembered sets 4319 // are completely up-to-date wrt to references to the humongous object. 4320 // 4321 // Other implementation considerations: 4322 // - never consider object arrays at this time because they would pose 4323 // considerable effort for cleaning up the the remembered sets. This is 4324 // required because stale remembered sets might reference locations that 4325 // are currently allocated into. 4326 uint region_idx = r->hrm_index(); 4327 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4328 !r->rem_set()->is_empty()) { 4329 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", 4330 region_idx, 4331 (size_t)obj->size() * HeapWordSize, 4332 p2i(r->bottom()), 4333 r->rem_set()->occupied(), 4334 r->rem_set()->strong_code_roots_list_length(), 4335 next_bitmap->is_marked(r->bottom()), 4336 g1h->is_humongous_reclaim_candidate(region_idx), 4337 obj->is_typeArray() 4338 ); 4339 return false; 4340 } 4341 4342 guarantee(obj->is_typeArray(), 4343 "Only eagerly reclaiming type arrays is supported, but the object " 4344 PTR_FORMAT " is not.", p2i(r->bottom())); 4345 4346 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", 4347 region_idx, 4348 (size_t)obj->size() * HeapWordSize, 4349 p2i(r->bottom()), 4350 r->rem_set()->occupied(), 4351 r->rem_set()->strong_code_roots_list_length(), 4352 next_bitmap->is_marked(r->bottom()), 4353 g1h->is_humongous_reclaim_candidate(region_idx), 4354 obj->is_typeArray() 4355 ); 4356 4357 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4358 cm->humongous_object_eagerly_reclaimed(r); 4359 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4360 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4361 region_idx, 4362 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4363 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4364 _humongous_objects_reclaimed++; 4365 do { 4366 HeapRegion* next = g1h->next_region_in_humongous(r); 4367 _freed_bytes += r->used(); 4368 r->set_containing_set(NULL); 4369 _humongous_regions_reclaimed++; 4370 g1h->free_humongous_region(r, _free_region_list); 4371 r = next; 4372 } while (r != NULL); 4373 4374 return false; 4375 } 4376 4377 uint humongous_objects_reclaimed() { 4378 return _humongous_objects_reclaimed; 4379 } 4380 4381 uint humongous_regions_reclaimed() { 4382 return _humongous_regions_reclaimed; 4383 } 4384 4385 size_t bytes_freed() const { 4386 return _freed_bytes; 4387 } 4388 }; 4389 4390 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4391 assert_at_safepoint_on_vm_thread(); 4392 4393 if (!G1EagerReclaimHumongousObjects || 4394 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4395 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4396 return; 4397 } 4398 4399 double start_time = os::elapsedTime(); 4400 4401 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4402 4403 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4404 heap_region_iterate(&cl); 4405 4406 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4407 4408 G1HRPrinter* hrp = hr_printer(); 4409 if (hrp->is_active()) { 4410 FreeRegionListIterator iter(&local_cleanup_list); 4411 while (iter.more_available()) { 4412 HeapRegion* hr = iter.get_next(); 4413 hrp->cleanup(hr); 4414 } 4415 } 4416 4417 prepend_to_freelist(&local_cleanup_list); 4418 decrement_summary_bytes(cl.bytes_freed()); 4419 4420 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4421 cl.humongous_objects_reclaimed()); 4422 } 4423 4424 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4425 public: 4426 virtual bool do_heap_region(HeapRegion* r) { 4427 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4428 G1CollectedHeap::heap()->clear_in_cset(r); 4429 r->set_young_index_in_cset(-1); 4430 return false; 4431 } 4432 }; 4433 4434 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4435 G1AbandonCollectionSetClosure cl; 4436 collection_set->iterate(&cl); 4437 4438 collection_set->clear(); 4439 collection_set->stop_incremental_building(); 4440 } 4441 4442 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4443 return _allocator->is_retained_old_region(hr); 4444 } 4445 4446 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4447 _eden.add(hr); 4448 _policy->set_region_eden(hr); 4449 } 4450 4451 #ifdef ASSERT 4452 4453 class NoYoungRegionsClosure: public HeapRegionClosure { 4454 private: 4455 bool _success; 4456 public: 4457 NoYoungRegionsClosure() : _success(true) { } 4458 bool do_heap_region(HeapRegion* r) { 4459 if (r->is_young()) { 4460 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4461 p2i(r->bottom()), p2i(r->end())); 4462 _success = false; 4463 } 4464 return false; 4465 } 4466 bool success() { return _success; } 4467 }; 4468 4469 bool G1CollectedHeap::check_young_list_empty() { 4470 bool ret = (young_regions_count() == 0); 4471 4472 NoYoungRegionsClosure closure; 4473 heap_region_iterate(&closure); 4474 ret = ret && closure.success(); 4475 4476 return ret; 4477 } 4478 4479 #endif // ASSERT 4480 4481 class TearDownRegionSetsClosure : public HeapRegionClosure { 4482 HeapRegionSet *_old_set; 4483 4484 public: 4485 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4486 4487 bool do_heap_region(HeapRegion* r) { 4488 if (r->is_old()) { 4489 _old_set->remove(r); 4490 } else if(r->is_young()) { 4491 r->uninstall_surv_rate_group(); 4492 } else { 4493 // We ignore free regions, we'll empty the free list afterwards. 4494 // We ignore humongous and archive regions, we're not tearing down these 4495 // sets. 4496 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4497 "it cannot be another type"); 4498 } 4499 return false; 4500 } 4501 4502 ~TearDownRegionSetsClosure() { 4503 assert(_old_set->is_empty(), "post-condition"); 4504 } 4505 }; 4506 4507 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4508 assert_at_safepoint_on_vm_thread(); 4509 4510 if (!free_list_only) { 4511 TearDownRegionSetsClosure cl(&_old_set); 4512 heap_region_iterate(&cl); 4513 4514 // Note that emptying the _young_list is postponed and instead done as 4515 // the first step when rebuilding the regions sets again. The reason for 4516 // this is that during a full GC string deduplication needs to know if 4517 // a collected region was young or old when the full GC was initiated. 4518 } 4519 _hrm->remove_all_free_regions(); 4520 } 4521 4522 void G1CollectedHeap::increase_used(size_t bytes) { 4523 _summary_bytes_used += bytes; 4524 } 4525 4526 void G1CollectedHeap::decrease_used(size_t bytes) { 4527 assert(_summary_bytes_used >= bytes, 4528 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4529 _summary_bytes_used, bytes); 4530 _summary_bytes_used -= bytes; 4531 } 4532 4533 void G1CollectedHeap::set_used(size_t bytes) { 4534 _summary_bytes_used = bytes; 4535 } 4536 4537 class RebuildRegionSetsClosure : public HeapRegionClosure { 4538 private: 4539 bool _free_list_only; 4540 4541 HeapRegionSet* _old_set; 4542 HeapRegionManager* _hrm; 4543 4544 size_t _total_used; 4545 4546 public: 4547 RebuildRegionSetsClosure(bool free_list_only, 4548 HeapRegionSet* old_set, 4549 HeapRegionManager* hrm) : 4550 _free_list_only(free_list_only), 4551 _old_set(old_set), _hrm(hrm), _total_used(0) { 4552 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4553 if (!free_list_only) { 4554 assert(_old_set->is_empty(), "pre-condition"); 4555 } 4556 } 4557 4558 bool do_heap_region(HeapRegion* r) { 4559 if (r->is_empty()) { 4560 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4561 // Add free regions to the free list 4562 r->set_free(); 4563 _hrm->insert_into_free_list(r); 4564 } else if (!_free_list_only) { 4565 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4566 4567 if (r->is_archive() || r->is_humongous()) { 4568 // We ignore archive and humongous regions. We left these sets unchanged. 4569 } else { 4570 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4571 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4572 r->move_to_old(); 4573 _old_set->add(r); 4574 } 4575 _total_used += r->used(); 4576 } 4577 4578 return false; 4579 } 4580 4581 size_t total_used() { 4582 return _total_used; 4583 } 4584 }; 4585 4586 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4587 assert_at_safepoint_on_vm_thread(); 4588 4589 if (!free_list_only) { 4590 _eden.clear(); 4591 _survivor.clear(); 4592 } 4593 4594 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4595 heap_region_iterate(&cl); 4596 4597 if (!free_list_only) { 4598 set_used(cl.total_used()); 4599 if (_archive_allocator != NULL) { 4600 _archive_allocator->clear_used(); 4601 } 4602 } 4603 assert(used() == recalculate_used(), 4604 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4605 used(), recalculate_used()); 4606 } 4607 4608 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4609 HeapRegion* hr = heap_region_containing(p); 4610 return hr->is_in(p); 4611 } 4612 4613 // Methods for the mutator alloc region 4614 4615 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4616 bool force) { 4617 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4618 bool should_allocate = policy()->should_allocate_mutator_region(); 4619 if (force || should_allocate) { 4620 HeapRegion* new_alloc_region = new_region(word_size, 4621 HeapRegionType::Eden, 4622 false /* do_expand */); 4623 if (new_alloc_region != NULL) { 4624 set_region_short_lived_locked(new_alloc_region); 4625 _hr_printer.alloc(new_alloc_region, !should_allocate); 4626 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4627 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4628 return new_alloc_region; 4629 } 4630 } 4631 return NULL; 4632 } 4633 4634 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4635 size_t allocated_bytes) { 4636 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4637 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4638 4639 collection_set()->add_eden_region(alloc_region); 4640 increase_used(allocated_bytes); 4641 _hr_printer.retire(alloc_region); 4642 // We update the eden sizes here, when the region is retired, 4643 // instead of when it's allocated, since this is the point that its 4644 // used space has been recorded in _summary_bytes_used. 4645 g1mm()->update_eden_size(); 4646 } 4647 4648 // Methods for the GC alloc regions 4649 4650 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4651 if (dest.is_old()) { 4652 return true; 4653 } else { 4654 return survivor_regions_count() < policy()->max_survivor_regions(); 4655 } 4656 } 4657 4658 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4659 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4660 4661 if (!has_more_regions(dest)) { 4662 return NULL; 4663 } 4664 4665 HeapRegionType type; 4666 if (dest.is_young()) { 4667 type = HeapRegionType::Survivor; 4668 } else { 4669 type = HeapRegionType::Old; 4670 } 4671 4672 HeapRegion* new_alloc_region = new_region(word_size, 4673 type, 4674 true /* do_expand */); 4675 4676 if (new_alloc_region != NULL) { 4677 if (type.is_survivor()) { 4678 new_alloc_region->set_survivor(); 4679 _survivor.add(new_alloc_region); 4680 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4681 } else { 4682 new_alloc_region->set_old(); 4683 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4684 } 4685 _policy->remset_tracker()->update_at_allocate(new_alloc_region); 4686 _hr_printer.alloc(new_alloc_region); 4687 return new_alloc_region; 4688 } 4689 return NULL; 4690 } 4691 4692 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4693 size_t allocated_bytes, 4694 InCSetState dest) { 4695 policy()->record_bytes_copied_during_gc(allocated_bytes); 4696 if (dest.is_old()) { 4697 old_set_add(alloc_region); 4698 } 4699 4700 bool const during_im = collector_state()->in_initial_mark_gc(); 4701 if (during_im && allocated_bytes > 0) { 4702 _cm->root_regions()->add(alloc_region); 4703 } 4704 _hr_printer.retire(alloc_region); 4705 } 4706 4707 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4708 bool expanded = false; 4709 uint index = _hrm->find_highest_free(&expanded); 4710 4711 if (index != G1_NO_HRM_INDEX) { 4712 if (expanded) { 4713 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4714 HeapRegion::GrainWords * HeapWordSize); 4715 } 4716 _hrm->allocate_free_regions_starting_at(index, 1); 4717 return region_at(index); 4718 } 4719 return NULL; 4720 } 4721 4722 // Optimized nmethod scanning 4723 4724 class RegisterNMethodOopClosure: public OopClosure { 4725 G1CollectedHeap* _g1h; 4726 nmethod* _nm; 4727 4728 template <class T> void do_oop_work(T* p) { 4729 T heap_oop = RawAccess<>::oop_load(p); 4730 if (!CompressedOops::is_null(heap_oop)) { 4731 oop obj = CompressedOops::decode_not_null(heap_oop); 4732 HeapRegion* hr = _g1h->heap_region_containing(obj); 4733 assert(!hr->is_continues_humongous(), 4734 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4735 " starting at " HR_FORMAT, 4736 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4737 4738 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4739 hr->add_strong_code_root_locked(_nm); 4740 } 4741 } 4742 4743 public: 4744 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4745 _g1h(g1h), _nm(nm) {} 4746 4747 void do_oop(oop* p) { do_oop_work(p); } 4748 void do_oop(narrowOop* p) { do_oop_work(p); } 4749 }; 4750 4751 class UnregisterNMethodOopClosure: public OopClosure { 4752 G1CollectedHeap* _g1h; 4753 nmethod* _nm; 4754 4755 template <class T> void do_oop_work(T* p) { 4756 T heap_oop = RawAccess<>::oop_load(p); 4757 if (!CompressedOops::is_null(heap_oop)) { 4758 oop obj = CompressedOops::decode_not_null(heap_oop); 4759 HeapRegion* hr = _g1h->heap_region_containing(obj); 4760 assert(!hr->is_continues_humongous(), 4761 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4762 " starting at " HR_FORMAT, 4763 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4764 4765 hr->remove_strong_code_root(_nm); 4766 } 4767 } 4768 4769 public: 4770 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4771 _g1h(g1h), _nm(nm) {} 4772 4773 void do_oop(oop* p) { do_oop_work(p); } 4774 void do_oop(narrowOop* p) { do_oop_work(p); } 4775 }; 4776 4777 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4778 guarantee(nm != NULL, "sanity"); 4779 RegisterNMethodOopClosure reg_cl(this, nm); 4780 nm->oops_do(®_cl); 4781 } 4782 4783 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4784 guarantee(nm != NULL, "sanity"); 4785 UnregisterNMethodOopClosure reg_cl(this, nm); 4786 nm->oops_do(®_cl, true); 4787 } 4788 4789 void G1CollectedHeap::purge_code_root_memory() { 4790 double purge_start = os::elapsedTime(); 4791 G1CodeRootSet::purge(); 4792 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4793 phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4794 } 4795 4796 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4797 G1CollectedHeap* _g1h; 4798 4799 public: 4800 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4801 _g1h(g1h) {} 4802 4803 void do_code_blob(CodeBlob* cb) { 4804 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4805 if (nm == NULL) { 4806 return; 4807 } 4808 4809 _g1h->register_nmethod(nm); 4810 } 4811 }; 4812 4813 void G1CollectedHeap::rebuild_strong_code_roots() { 4814 RebuildStrongCodeRootClosure blob_cl(this); 4815 CodeCache::blobs_do(&blob_cl); 4816 } 4817 4818 void G1CollectedHeap::initialize_serviceability() { 4819 _g1mm->initialize_serviceability(); 4820 } 4821 4822 MemoryUsage G1CollectedHeap::memory_usage() { 4823 return _g1mm->memory_usage(); 4824 } 4825 4826 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4827 return _g1mm->memory_managers(); 4828 } 4829 4830 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4831 return _g1mm->memory_pools(); 4832 }