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(jbyte* 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(jbyte* 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 _g1_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 _g1_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 g1_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() && g1_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 (g1_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 g1_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 && g1_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 g1_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 g1_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 _g1_policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)), 1514 _heap_sizing_policy(NULL), 1515 _collection_set(this, _g1_policy), 1516 _hot_card_cache(NULL), 1517 _g1_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, _g1_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 = g1_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 Shared_SATB_Q_lock); 1681 1682 // process_completed_buffers_threshold and max_completed_buffers are updated 1683 // later, based on the concurrent refinement object. 1684 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1685 &bs->dirty_card_queue_buffer_allocator(), 1686 Shared_DirtyCardQ_lock, 1687 true); // init_free_ids 1688 1689 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1690 &bs->dirty_card_queue_buffer_allocator(), 1691 Shared_DirtyCardQ_lock); 1692 1693 // Create the hot card cache. 1694 _hot_card_cache = new G1HotCardCache(this); 1695 1696 // Carve out the G1 part of the heap. 1697 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1698 size_t page_size = actual_reserved_page_size(heap_rs); 1699 G1RegionToSpaceMapper* heap_storage = 1700 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1701 g1_rs.size(), 1702 page_size, 1703 HeapRegion::GrainBytes, 1704 1, 1705 mtJavaHeap); 1706 if(heap_storage == NULL) { 1707 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1708 return JNI_ERR; 1709 } 1710 1711 os::trace_page_sizes("Heap", 1712 collector_policy()->min_heap_byte_size(), 1713 max_byte_size, 1714 page_size, 1715 heap_rs.base(), 1716 heap_rs.size()); 1717 heap_storage->set_mapping_changed_listener(&_listener); 1718 1719 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1720 G1RegionToSpaceMapper* bot_storage = 1721 create_aux_memory_mapper("Block Offset Table", 1722 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1723 G1BlockOffsetTable::heap_map_factor()); 1724 1725 G1RegionToSpaceMapper* cardtable_storage = 1726 create_aux_memory_mapper("Card Table", 1727 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1728 G1CardTable::heap_map_factor()); 1729 1730 G1RegionToSpaceMapper* card_counts_storage = 1731 create_aux_memory_mapper("Card Counts Table", 1732 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1733 G1CardCounts::heap_map_factor()); 1734 1735 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1736 G1RegionToSpaceMapper* prev_bitmap_storage = 1737 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1738 G1RegionToSpaceMapper* next_bitmap_storage = 1739 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1740 1741 _hrm = HeapRegionManager::create_manager(this, g1_collector_policy()); 1742 1743 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1744 _card_table->initialize(cardtable_storage); 1745 // Do later initialization work for concurrent refinement. 1746 _hot_card_cache->initialize(card_counts_storage); 1747 1748 // 6843694 - ensure that the maximum region index can fit 1749 // in the remembered set structures. 1750 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1751 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1752 1753 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1754 // start within the first card. 1755 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1756 // Also create a G1 rem set. 1757 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1758 _g1_rem_set->initialize(max_reserved_capacity(), max_regions()); 1759 1760 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1761 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1762 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1763 "too many cards per region"); 1764 1765 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1766 1767 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1768 1769 { 1770 HeapWord* start = _hrm->reserved().start(); 1771 HeapWord* end = _hrm->reserved().end(); 1772 size_t granularity = HeapRegion::GrainBytes; 1773 1774 _in_cset_fast_test.initialize(start, end, granularity); 1775 _humongous_reclaim_candidates.initialize(start, end, granularity); 1776 } 1777 1778 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1779 true /* are_GC_task_threads */, 1780 false /* are_ConcurrentGC_threads */); 1781 if (_workers == NULL) { 1782 return JNI_ENOMEM; 1783 } 1784 _workers->initialize_workers(); 1785 1786 // Create the G1ConcurrentMark data structure and thread. 1787 // (Must do this late, so that "max_regions" is defined.) 1788 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1789 if (_cm == NULL || !_cm->completed_initialization()) { 1790 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1791 return JNI_ENOMEM; 1792 } 1793 _cm_thread = _cm->cm_thread(); 1794 1795 // Now expand into the initial heap size. 1796 if (!expand(init_byte_size, _workers)) { 1797 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1798 return JNI_ENOMEM; 1799 } 1800 1801 // Perform any initialization actions delegated to the policy. 1802 g1_policy()->init(this, &_collection_set); 1803 1804 jint ecode = initialize_concurrent_refinement(); 1805 if (ecode != JNI_OK) { 1806 return ecode; 1807 } 1808 1809 ecode = initialize_young_gen_sampling_thread(); 1810 if (ecode != JNI_OK) { 1811 return ecode; 1812 } 1813 1814 { 1815 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1816 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone()); 1817 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone()); 1818 } 1819 1820 // Here we allocate the dummy HeapRegion that is required by the 1821 // G1AllocRegion class. 1822 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1823 1824 // We'll re-use the same region whether the alloc region will 1825 // require BOT updates or not and, if it doesn't, then a non-young 1826 // region will complain that it cannot support allocations without 1827 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1828 dummy_region->set_eden(); 1829 // Make sure it's full. 1830 dummy_region->set_top(dummy_region->end()); 1831 G1AllocRegion::setup(this, dummy_region); 1832 1833 _allocator->init_mutator_alloc_region(); 1834 1835 // Do create of the monitoring and management support so that 1836 // values in the heap have been properly initialized. 1837 _g1mm = new G1MonitoringSupport(this); 1838 1839 G1StringDedup::initialize(); 1840 1841 _preserved_marks_set.init(ParallelGCThreads); 1842 1843 _collection_set.initialize(max_regions()); 1844 1845 return JNI_OK; 1846 } 1847 1848 void G1CollectedHeap::stop() { 1849 // Stop all concurrent threads. We do this to make sure these threads 1850 // do not continue to execute and access resources (e.g. logging) 1851 // that are destroyed during shutdown. 1852 _cr->stop(); 1853 _young_gen_sampling_thread->stop(); 1854 _cm_thread->stop(); 1855 if (G1StringDedup::is_enabled()) { 1856 G1StringDedup::stop(); 1857 } 1858 } 1859 1860 void G1CollectedHeap::safepoint_synchronize_begin() { 1861 SuspendibleThreadSet::synchronize(); 1862 } 1863 1864 void G1CollectedHeap::safepoint_synchronize_end() { 1865 SuspendibleThreadSet::desynchronize(); 1866 } 1867 1868 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1869 return HeapRegion::max_region_size(); 1870 } 1871 1872 void G1CollectedHeap::post_initialize() { 1873 CollectedHeap::post_initialize(); 1874 ref_processing_init(); 1875 } 1876 1877 void G1CollectedHeap::ref_processing_init() { 1878 // Reference processing in G1 currently works as follows: 1879 // 1880 // * There are two reference processor instances. One is 1881 // used to record and process discovered references 1882 // during concurrent marking; the other is used to 1883 // record and process references during STW pauses 1884 // (both full and incremental). 1885 // * Both ref processors need to 'span' the entire heap as 1886 // the regions in the collection set may be dotted around. 1887 // 1888 // * For the concurrent marking ref processor: 1889 // * Reference discovery is enabled at initial marking. 1890 // * Reference discovery is disabled and the discovered 1891 // references processed etc during remarking. 1892 // * Reference discovery is MT (see below). 1893 // * Reference discovery requires a barrier (see below). 1894 // * Reference processing may or may not be MT 1895 // (depending on the value of ParallelRefProcEnabled 1896 // and ParallelGCThreads). 1897 // * A full GC disables reference discovery by the CM 1898 // ref processor and abandons any entries on it's 1899 // discovered lists. 1900 // 1901 // * For the STW processor: 1902 // * Non MT discovery is enabled at the start of a full GC. 1903 // * Processing and enqueueing during a full GC is non-MT. 1904 // * During a full GC, references are processed after marking. 1905 // 1906 // * Discovery (may or may not be MT) is enabled at the start 1907 // of an incremental evacuation pause. 1908 // * References are processed near the end of a STW evacuation pause. 1909 // * For both types of GC: 1910 // * Discovery is atomic - i.e. not concurrent. 1911 // * Reference discovery will not need a barrier. 1912 1913 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1914 1915 // Concurrent Mark ref processor 1916 _ref_processor_cm = 1917 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1918 mt_processing, // mt processing 1919 ParallelGCThreads, // degree of mt processing 1920 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1921 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1922 false, // Reference discovery is not atomic 1923 &_is_alive_closure_cm, // is alive closure 1924 true); // allow changes to number of processing threads 1925 1926 // STW ref processor 1927 _ref_processor_stw = 1928 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1929 mt_processing, // mt processing 1930 ParallelGCThreads, // degree of mt processing 1931 (ParallelGCThreads > 1), // mt discovery 1932 ParallelGCThreads, // degree of mt discovery 1933 true, // Reference discovery is atomic 1934 &_is_alive_closure_stw, // is alive closure 1935 true); // allow changes to number of processing threads 1936 } 1937 1938 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1939 return _collector_policy; 1940 } 1941 1942 G1CollectorPolicy* G1CollectedHeap::g1_collector_policy() const { 1943 return _collector_policy; 1944 } 1945 1946 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1947 return &_soft_ref_policy; 1948 } 1949 1950 size_t G1CollectedHeap::capacity() const { 1951 return _hrm->length() * HeapRegion::GrainBytes; 1952 } 1953 1954 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1955 return _hrm->total_free_bytes(); 1956 } 1957 1958 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1959 _hot_card_cache->drain(cl, worker_i); 1960 } 1961 1962 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1963 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1964 size_t n_completed_buffers = 0; 1965 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1966 n_completed_buffers++; 1967 } 1968 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!"); 1969 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1970 } 1971 1972 // Computes the sum of the storage used by the various regions. 1973 size_t G1CollectedHeap::used() const { 1974 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1975 if (_archive_allocator != NULL) { 1976 result += _archive_allocator->used(); 1977 } 1978 return result; 1979 } 1980 1981 size_t G1CollectedHeap::used_unlocked() const { 1982 return _summary_bytes_used; 1983 } 1984 1985 class SumUsedClosure: public HeapRegionClosure { 1986 size_t _used; 1987 public: 1988 SumUsedClosure() : _used(0) {} 1989 bool do_heap_region(HeapRegion* r) { 1990 _used += r->used(); 1991 return false; 1992 } 1993 size_t result() { return _used; } 1994 }; 1995 1996 size_t G1CollectedHeap::recalculate_used() const { 1997 SumUsedClosure blk; 1998 heap_region_iterate(&blk); 1999 return blk.result(); 2000 } 2001 2002 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2003 switch (cause) { 2004 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2005 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2006 case GCCause::_wb_conc_mark: return true; 2007 default : return false; 2008 } 2009 } 2010 2011 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2012 switch (cause) { 2013 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2014 case GCCause::_g1_humongous_allocation: return true; 2015 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2016 default: return is_user_requested_concurrent_full_gc(cause); 2017 } 2018 } 2019 2020 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2021 if(g1_policy()->force_upgrade_to_full()) { 2022 return true; 2023 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2024 return false; 2025 } else if (has_regions_left_for_allocation()) { 2026 return false; 2027 } else { 2028 return true; 2029 } 2030 } 2031 2032 #ifndef PRODUCT 2033 void G1CollectedHeap::allocate_dummy_regions() { 2034 // Let's fill up most of the region 2035 size_t word_size = HeapRegion::GrainWords - 1024; 2036 // And as a result the region we'll allocate will be humongous. 2037 guarantee(is_humongous(word_size), "sanity"); 2038 2039 // _filler_array_max_size is set to humongous object threshold 2040 // but temporarily change it to use CollectedHeap::fill_with_object(). 2041 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2042 2043 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2044 // Let's use the existing mechanism for the allocation 2045 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2046 if (dummy_obj != NULL) { 2047 MemRegion mr(dummy_obj, word_size); 2048 CollectedHeap::fill_with_object(mr); 2049 } else { 2050 // If we can't allocate once, we probably cannot allocate 2051 // again. Let's get out of the loop. 2052 break; 2053 } 2054 } 2055 } 2056 #endif // !PRODUCT 2057 2058 void G1CollectedHeap::increment_old_marking_cycles_started() { 2059 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2060 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2061 "Wrong marking cycle count (started: %d, completed: %d)", 2062 _old_marking_cycles_started, _old_marking_cycles_completed); 2063 2064 _old_marking_cycles_started++; 2065 } 2066 2067 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2068 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2069 2070 // We assume that if concurrent == true, then the caller is a 2071 // concurrent thread that was joined the Suspendible Thread 2072 // Set. If there's ever a cheap way to check this, we should add an 2073 // assert here. 2074 2075 // Given that this method is called at the end of a Full GC or of a 2076 // concurrent cycle, and those can be nested (i.e., a Full GC can 2077 // interrupt a concurrent cycle), the number of full collections 2078 // completed should be either one (in the case where there was no 2079 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2080 // behind the number of full collections started. 2081 2082 // This is the case for the inner caller, i.e. a Full GC. 2083 assert(concurrent || 2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2085 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2086 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2087 "is inconsistent with _old_marking_cycles_completed = %u", 2088 _old_marking_cycles_started, _old_marking_cycles_completed); 2089 2090 // This is the case for the outer caller, i.e. the concurrent cycle. 2091 assert(!concurrent || 2092 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2093 "for outer caller (concurrent cycle): " 2094 "_old_marking_cycles_started = %u " 2095 "is inconsistent with _old_marking_cycles_completed = %u", 2096 _old_marking_cycles_started, _old_marking_cycles_completed); 2097 2098 _old_marking_cycles_completed += 1; 2099 2100 // We need to clear the "in_progress" flag in the CM thread before 2101 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2102 // is set) so that if a waiter requests another System.gc() it doesn't 2103 // incorrectly see that a marking cycle is still in progress. 2104 if (concurrent) { 2105 _cm_thread->set_idle(); 2106 } 2107 2108 // This notify_all() will ensure that a thread that called 2109 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2110 // and it's waiting for a full GC to finish will be woken up. It is 2111 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2112 FullGCCount_lock->notify_all(); 2113 } 2114 2115 void G1CollectedHeap::collect(GCCause::Cause cause) { 2116 assert_heap_not_locked(); 2117 2118 uint gc_count_before; 2119 uint old_marking_count_before; 2120 uint full_gc_count_before; 2121 bool retry_gc; 2122 2123 do { 2124 retry_gc = false; 2125 2126 { 2127 MutexLocker ml(Heap_lock); 2128 2129 // Read the GC count while holding the Heap_lock 2130 gc_count_before = total_collections(); 2131 full_gc_count_before = total_full_collections(); 2132 old_marking_count_before = _old_marking_cycles_started; 2133 } 2134 2135 if (should_do_concurrent_full_gc(cause)) { 2136 // Schedule an initial-mark evacuation pause that will start a 2137 // concurrent cycle. We're setting word_size to 0 which means that 2138 // we are not requesting a post-GC allocation. 2139 VM_G1CollectForAllocation op(0, /* word_size */ 2140 gc_count_before, 2141 cause, 2142 true, /* should_initiate_conc_mark */ 2143 g1_policy()->max_pause_time_ms()); 2144 VMThread::execute(&op); 2145 if (!op.pause_succeeded()) { 2146 if (old_marking_count_before == _old_marking_cycles_started) { 2147 retry_gc = op.should_retry_gc(); 2148 } else { 2149 // A Full GC happened while we were trying to schedule the 2150 // initial-mark GC. No point in starting a new cycle given 2151 // that the whole heap was collected anyway. 2152 } 2153 2154 if (retry_gc) { 2155 if (GCLocker::is_active_and_needs_gc()) { 2156 GCLocker::stall_until_clear(); 2157 } 2158 } 2159 } 2160 } else { 2161 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2162 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2163 2164 // Schedule a standard evacuation pause. We're setting word_size 2165 // to 0 which means that we are not requesting a post-GC allocation. 2166 VM_G1CollectForAllocation op(0, /* word_size */ 2167 gc_count_before, 2168 cause, 2169 false, /* should_initiate_conc_mark */ 2170 g1_policy()->max_pause_time_ms()); 2171 VMThread::execute(&op); 2172 } else { 2173 // Schedule a Full GC. 2174 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2175 VMThread::execute(&op); 2176 } 2177 } 2178 } while (retry_gc); 2179 } 2180 2181 bool G1CollectedHeap::is_in(const void* p) const { 2182 if (_hrm->reserved().contains(p)) { 2183 // Given that we know that p is in the reserved space, 2184 // heap_region_containing() should successfully 2185 // return the containing region. 2186 HeapRegion* hr = heap_region_containing(p); 2187 return hr->is_in(p); 2188 } else { 2189 return false; 2190 } 2191 } 2192 2193 #ifdef ASSERT 2194 bool G1CollectedHeap::is_in_exact(const void* p) const { 2195 bool contains = reserved_region().contains(p); 2196 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2197 if (contains && available) { 2198 return true; 2199 } else { 2200 return false; 2201 } 2202 } 2203 #endif 2204 2205 // Iteration functions. 2206 2207 // Iterates an ObjectClosure over all objects within a HeapRegion. 2208 2209 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2210 ObjectClosure* _cl; 2211 public: 2212 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2213 bool do_heap_region(HeapRegion* r) { 2214 if (!r->is_continues_humongous()) { 2215 r->object_iterate(_cl); 2216 } 2217 return false; 2218 } 2219 }; 2220 2221 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2222 IterateObjectClosureRegionClosure blk(cl); 2223 heap_region_iterate(&blk); 2224 } 2225 2226 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2227 _hrm->iterate(cl); 2228 } 2229 2230 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2231 HeapRegionClaimer *hrclaimer, 2232 uint worker_id) const { 2233 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2234 } 2235 2236 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2237 HeapRegionClaimer *hrclaimer) const { 2238 _hrm->par_iterate(cl, hrclaimer, 0); 2239 } 2240 2241 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2242 _collection_set.iterate(cl); 2243 } 2244 2245 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2246 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2247 } 2248 2249 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2250 HeapRegion* hr = heap_region_containing(addr); 2251 return hr->block_start(addr); 2252 } 2253 2254 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2255 HeapRegion* hr = heap_region_containing(addr); 2256 return hr->block_size(addr); 2257 } 2258 2259 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2260 HeapRegion* hr = heap_region_containing(addr); 2261 return hr->block_is_obj(addr); 2262 } 2263 2264 bool G1CollectedHeap::supports_tlab_allocation() const { 2265 return true; 2266 } 2267 2268 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2269 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2270 } 2271 2272 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2273 return _eden.length() * HeapRegion::GrainBytes; 2274 } 2275 2276 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2277 // must be equal to the humongous object limit. 2278 size_t G1CollectedHeap::max_tlab_size() const { 2279 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2280 } 2281 2282 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2283 return _allocator->unsafe_max_tlab_alloc(); 2284 } 2285 2286 size_t G1CollectedHeap::max_capacity() const { 2287 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2288 } 2289 2290 size_t G1CollectedHeap::max_reserved_capacity() const { 2291 return _hrm->max_length() * HeapRegion::GrainBytes; 2292 } 2293 2294 jlong G1CollectedHeap::millis_since_last_gc() { 2295 // See the notes in GenCollectedHeap::millis_since_last_gc() 2296 // for more information about the implementation. 2297 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2298 _g1_policy->collection_pause_end_millis(); 2299 if (ret_val < 0) { 2300 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2301 ". returning zero instead.", ret_val); 2302 return 0; 2303 } 2304 return ret_val; 2305 } 2306 2307 void G1CollectedHeap::deduplicate_string(oop str) { 2308 assert(java_lang_String::is_instance(str), "invariant"); 2309 2310 if (G1StringDedup::is_enabled()) { 2311 G1StringDedup::deduplicate(str); 2312 } 2313 } 2314 2315 void G1CollectedHeap::prepare_for_verify() { 2316 _verifier->prepare_for_verify(); 2317 } 2318 2319 void G1CollectedHeap::verify(VerifyOption vo) { 2320 _verifier->verify(vo); 2321 } 2322 2323 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2324 return true; 2325 } 2326 2327 const char* const* G1CollectedHeap::concurrent_phases() const { 2328 return _cm_thread->concurrent_phases(); 2329 } 2330 2331 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2332 return _cm_thread->request_concurrent_phase(phase); 2333 } 2334 2335 class PrintRegionClosure: public HeapRegionClosure { 2336 outputStream* _st; 2337 public: 2338 PrintRegionClosure(outputStream* st) : _st(st) {} 2339 bool do_heap_region(HeapRegion* r) { 2340 r->print_on(_st); 2341 return false; 2342 } 2343 }; 2344 2345 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2346 const HeapRegion* hr, 2347 const VerifyOption vo) const { 2348 switch (vo) { 2349 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2350 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2351 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2352 default: ShouldNotReachHere(); 2353 } 2354 return false; // keep some compilers happy 2355 } 2356 2357 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2358 const VerifyOption vo) const { 2359 switch (vo) { 2360 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2361 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2362 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2363 default: ShouldNotReachHere(); 2364 } 2365 return false; // keep some compilers happy 2366 } 2367 2368 void G1CollectedHeap::print_heap_regions() const { 2369 LogTarget(Trace, gc, heap, region) lt; 2370 if (lt.is_enabled()) { 2371 LogStream ls(lt); 2372 print_regions_on(&ls); 2373 } 2374 } 2375 2376 void G1CollectedHeap::print_on(outputStream* st) const { 2377 st->print(" %-20s", "garbage-first heap"); 2378 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2379 capacity()/K, used_unlocked()/K); 2380 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2381 p2i(_hrm->reserved().start()), 2382 p2i(_hrm->reserved().end())); 2383 st->cr(); 2384 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2385 uint young_regions = young_regions_count(); 2386 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2387 (size_t) young_regions * HeapRegion::GrainBytes / K); 2388 uint survivor_regions = survivor_regions_count(); 2389 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2390 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2391 st->cr(); 2392 MetaspaceUtils::print_on(st); 2393 } 2394 2395 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2396 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2397 "HS=humongous(starts), HC=humongous(continues), " 2398 "CS=collection set, F=free, A=archive, " 2399 "TAMS=top-at-mark-start (previous, next)"); 2400 PrintRegionClosure blk(st); 2401 heap_region_iterate(&blk); 2402 } 2403 2404 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2405 print_on(st); 2406 2407 // Print the per-region information. 2408 print_regions_on(st); 2409 } 2410 2411 void G1CollectedHeap::print_on_error(outputStream* st) const { 2412 this->CollectedHeap::print_on_error(st); 2413 2414 if (_cm != NULL) { 2415 st->cr(); 2416 _cm->print_on_error(st); 2417 } 2418 } 2419 2420 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2421 workers()->print_worker_threads_on(st); 2422 _cm_thread->print_on(st); 2423 st->cr(); 2424 _cm->print_worker_threads_on(st); 2425 _cr->print_threads_on(st); 2426 _young_gen_sampling_thread->print_on(st); 2427 if (G1StringDedup::is_enabled()) { 2428 G1StringDedup::print_worker_threads_on(st); 2429 } 2430 } 2431 2432 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2433 workers()->threads_do(tc); 2434 tc->do_thread(_cm_thread); 2435 _cm->threads_do(tc); 2436 _cr->threads_do(tc); 2437 tc->do_thread(_young_gen_sampling_thread); 2438 if (G1StringDedup::is_enabled()) { 2439 G1StringDedup::threads_do(tc); 2440 } 2441 } 2442 2443 void G1CollectedHeap::print_tracing_info() const { 2444 g1_rem_set()->print_summary_info(); 2445 concurrent_mark()->print_summary_info(); 2446 } 2447 2448 #ifndef PRODUCT 2449 // Helpful for debugging RSet issues. 2450 2451 class PrintRSetsClosure : public HeapRegionClosure { 2452 private: 2453 const char* _msg; 2454 size_t _occupied_sum; 2455 2456 public: 2457 bool do_heap_region(HeapRegion* r) { 2458 HeapRegionRemSet* hrrs = r->rem_set(); 2459 size_t occupied = hrrs->occupied(); 2460 _occupied_sum += occupied; 2461 2462 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2463 if (occupied == 0) { 2464 tty->print_cr(" RSet is empty"); 2465 } else { 2466 hrrs->print(); 2467 } 2468 tty->print_cr("----------"); 2469 return false; 2470 } 2471 2472 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2473 tty->cr(); 2474 tty->print_cr("========================================"); 2475 tty->print_cr("%s", msg); 2476 tty->cr(); 2477 } 2478 2479 ~PrintRSetsClosure() { 2480 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2481 tty->print_cr("========================================"); 2482 tty->cr(); 2483 } 2484 }; 2485 2486 void G1CollectedHeap::print_cset_rsets() { 2487 PrintRSetsClosure cl("Printing CSet RSets"); 2488 collection_set_iterate(&cl); 2489 } 2490 2491 void G1CollectedHeap::print_all_rsets() { 2492 PrintRSetsClosure cl("Printing All RSets");; 2493 heap_region_iterate(&cl); 2494 } 2495 #endif // PRODUCT 2496 2497 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2498 2499 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2500 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2501 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2502 2503 size_t eden_capacity_bytes = 2504 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2505 2506 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2507 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2508 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2509 } 2510 2511 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2512 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2513 stats->unused(), stats->used(), stats->region_end_waste(), 2514 stats->regions_filled(), stats->direct_allocated(), 2515 stats->failure_used(), stats->failure_waste()); 2516 } 2517 2518 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2519 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2520 gc_tracer->report_gc_heap_summary(when, heap_summary); 2521 2522 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2523 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2524 } 2525 2526 G1CollectedHeap* G1CollectedHeap::heap() { 2527 CollectedHeap* heap = Universe::heap(); 2528 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2529 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2530 return (G1CollectedHeap*)heap; 2531 } 2532 2533 void G1CollectedHeap::gc_prologue(bool full) { 2534 // always_do_update_barrier = false; 2535 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2536 2537 // This summary needs to be printed before incrementing total collections. 2538 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2539 2540 // Update common counters. 2541 increment_total_collections(full /* full gc */); 2542 if (full) { 2543 increment_old_marking_cycles_started(); 2544 } 2545 2546 // Fill TLAB's and such 2547 double start = os::elapsedTime(); 2548 ensure_parsability(true); 2549 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2550 } 2551 2552 void G1CollectedHeap::gc_epilogue(bool full) { 2553 // Update common counters. 2554 if (full) { 2555 // Update the number of full collections that have been completed. 2556 increment_old_marking_cycles_completed(false /* concurrent */); 2557 } 2558 2559 // We are at the end of the GC. Total collections has already been increased. 2560 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2561 2562 // FIXME: what is this about? 2563 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2564 // is set. 2565 #if COMPILER2_OR_JVMCI 2566 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2567 #endif 2568 // always_do_update_barrier = true; 2569 2570 double start = os::elapsedTime(); 2571 resize_all_tlabs(); 2572 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2573 2574 MemoryService::track_memory_usage(); 2575 // We have just completed a GC. Update the soft reference 2576 // policy with the new heap occupancy 2577 Universe::update_heap_info_at_gc(); 2578 } 2579 2580 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2581 uint gc_count_before, 2582 bool* succeeded, 2583 GCCause::Cause gc_cause) { 2584 assert_heap_not_locked_and_not_at_safepoint(); 2585 VM_G1CollectForAllocation op(word_size, 2586 gc_count_before, 2587 gc_cause, 2588 false, /* should_initiate_conc_mark */ 2589 g1_policy()->max_pause_time_ms()); 2590 VMThread::execute(&op); 2591 2592 HeapWord* result = op.result(); 2593 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2594 assert(result == NULL || ret_succeeded, 2595 "the result should be NULL if the VM did not succeed"); 2596 *succeeded = ret_succeeded; 2597 2598 assert_heap_not_locked(); 2599 return result; 2600 } 2601 2602 void G1CollectedHeap::do_concurrent_mark() { 2603 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2604 if (!_cm_thread->in_progress()) { 2605 _cm_thread->set_started(); 2606 CGC_lock->notify(); 2607 } 2608 } 2609 2610 size_t G1CollectedHeap::pending_card_num() { 2611 size_t extra_cards = 0; 2612 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2613 G1DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2614 extra_cards += dcq.size(); 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 + extra_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 jbyte* card_ptr = (jbyte*)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 g1_policy()->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 g1_policy()->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 g1_policy()->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 collection_set()->start_incremental_building(); 2865 2866 clear_cset_fast_test(); 2867 2868 guarantee(_eden.length() == 0, "eden should have been cleared"); 2869 g1_policy()->transfer_survivors_to_cset(survivor()); 2870 } 2871 2872 bool 2873 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2874 assert_at_safepoint_on_vm_thread(); 2875 guarantee(!is_gc_active(), "collection is not reentrant"); 2876 2877 if (GCLocker::check_active_before_gc()) { 2878 return false; 2879 } 2880 2881 _gc_timer_stw->register_gc_start(); 2882 2883 GCIdMark gc_id_mark; 2884 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2885 2886 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2887 ResourceMark rm; 2888 2889 g1_policy()->note_gc_start(); 2890 2891 wait_for_root_region_scanning(); 2892 2893 print_heap_before_gc(); 2894 print_heap_regions(); 2895 trace_heap_before_gc(_gc_tracer_stw); 2896 2897 _verifier->verify_region_sets_optional(); 2898 _verifier->verify_dirty_young_regions(); 2899 2900 // We should not be doing initial mark unless the conc mark thread is running 2901 if (!_cm_thread->should_terminate()) { 2902 // This call will decide whether this pause is an initial-mark 2903 // pause. If it is, in_initial_mark_gc() will return true 2904 // for the duration of this pause. 2905 g1_policy()->decide_on_conc_mark_initiation(); 2906 } 2907 2908 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2909 assert(!collector_state()->in_initial_mark_gc() || 2910 collector_state()->in_young_only_phase(), "sanity"); 2911 2912 // We also do not allow mixed GCs during marking. 2913 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2914 2915 // Record whether this pause is an initial mark. When the current 2916 // thread has completed its logging output and it's safe to signal 2917 // the CM thread, the flag's value in the policy has been reset. 2918 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2919 2920 // Inner scope for scope based logging, timers, and stats collection 2921 { 2922 G1EvacuationInfo evacuation_info; 2923 2924 if (collector_state()->in_initial_mark_gc()) { 2925 // We are about to start a marking cycle, so we increment the 2926 // full collection counter. 2927 increment_old_marking_cycles_started(); 2928 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2929 } 2930 2931 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2932 2933 GCTraceCPUTime tcpu; 2934 2935 G1HeapVerifier::G1VerifyType verify_type; 2936 FormatBuffer<> gc_string("Pause Young "); 2937 if (collector_state()->in_initial_mark_gc()) { 2938 gc_string.append("(Concurrent Start)"); 2939 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2940 } else if (collector_state()->in_young_only_phase()) { 2941 if (collector_state()->in_young_gc_before_mixed()) { 2942 gc_string.append("(Prepare Mixed)"); 2943 } else { 2944 gc_string.append("(Normal)"); 2945 } 2946 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2947 } else { 2948 gc_string.append("(Mixed)"); 2949 verify_type = G1HeapVerifier::G1VerifyMixed; 2950 } 2951 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2952 2953 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2954 workers()->active_workers(), 2955 Threads::number_of_non_daemon_threads()); 2956 active_workers = workers()->update_active_workers(active_workers); 2957 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2958 2959 G1MonitoringScope ms(g1mm(), 2960 false /* full_gc */, 2961 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2962 2963 G1HeapTransition heap_transition(this); 2964 size_t heap_used_bytes_before_gc = used(); 2965 2966 // Don't dynamically change the number of GC threads this early. A value of 2967 // 0 is used to indicate serial work. When parallel work is done, 2968 // it will be set. 2969 2970 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2971 IsGCActiveMark x; 2972 2973 gc_prologue(false); 2974 2975 if (VerifyRememberedSets) { 2976 log_info(gc, verify)("[Verifying RemSets before GC]"); 2977 VerifyRegionRemSetClosure v_cl; 2978 heap_region_iterate(&v_cl); 2979 } 2980 2981 _verifier->verify_before_gc(verify_type); 2982 2983 _verifier->check_bitmaps("GC Start"); 2984 2985 #if COMPILER2_OR_JVMCI 2986 DerivedPointerTable::clear(); 2987 #endif 2988 2989 // Please see comment in g1CollectedHeap.hpp and 2990 // G1CollectedHeap::ref_processing_init() to see how 2991 // reference processing currently works in G1. 2992 2993 // Enable discovery in the STW reference processor 2994 _ref_processor_stw->enable_discovery(); 2995 2996 { 2997 // We want to temporarily turn off discovery by the 2998 // CM ref processor, if necessary, and turn it back on 2999 // on again later if we do. Using a scoped 3000 // NoRefDiscovery object will do this. 3001 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3002 3003 // Forget the current alloc region (we might even choose it to be part 3004 // of the collection set!). 3005 _allocator->release_mutator_alloc_region(); 3006 3007 // This timing is only used by the ergonomics to handle our pause target. 3008 // It is unclear why this should not include the full pause. We will 3009 // investigate this in CR 7178365. 3010 // 3011 // Preserving the old comment here if that helps the investigation: 3012 // 3013 // The elapsed time induced by the start time below deliberately elides 3014 // the possible verification above. 3015 double sample_start_time_sec = os::elapsedTime(); 3016 3017 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3018 3019 if (collector_state()->in_initial_mark_gc()) { 3020 concurrent_mark()->pre_initial_mark(); 3021 } 3022 3023 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 3024 3025 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3026 3027 register_humongous_regions_with_cset(); 3028 3029 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3030 3031 // We call this after finalize_cset() to 3032 // ensure that the CSet has been finalized. 3033 _cm->verify_no_cset_oops(); 3034 3035 if (_hr_printer.is_active()) { 3036 G1PrintCollectionSetClosure cl(&_hr_printer); 3037 _collection_set.iterate(&cl); 3038 } 3039 3040 // Initialize the GC alloc regions. 3041 _allocator->init_gc_alloc_regions(evacuation_info); 3042 3043 G1ParScanThreadStateSet per_thread_states(this, 3044 workers()->active_workers(), 3045 collection_set()->young_region_length(), 3046 collection_set()->optional_region_length()); 3047 pre_evacuate_collection_set(); 3048 3049 // Actually do the work... 3050 evacuate_collection_set(&per_thread_states); 3051 evacuate_optional_collection_set(&per_thread_states); 3052 3053 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3054 3055 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3056 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3057 3058 eagerly_reclaim_humongous_regions(); 3059 3060 record_obj_copy_mem_stats(); 3061 _survivor_evac_stats.adjust_desired_plab_sz(); 3062 _old_evac_stats.adjust_desired_plab_sz(); 3063 3064 double start = os::elapsedTime(); 3065 start_new_collection_set(); 3066 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3067 3068 if (evacuation_failed()) { 3069 double recalculate_used_start = os::elapsedTime(); 3070 set_used(recalculate_used()); 3071 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3072 3073 if (_archive_allocator != NULL) { 3074 _archive_allocator->clear_used(); 3075 } 3076 for (uint i = 0; i < ParallelGCThreads; i++) { 3077 if (_evacuation_failed_info_array[i].has_failed()) { 3078 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3079 } 3080 } 3081 } else { 3082 // The "used" of the the collection set have already been subtracted 3083 // when they were freed. Add in the bytes evacuated. 3084 increase_used(g1_policy()->bytes_copied_during_gc()); 3085 } 3086 3087 if (collector_state()->in_initial_mark_gc()) { 3088 // We have to do this before we notify the CM threads that 3089 // they can start working to make sure that all the 3090 // appropriate initialization is done on the CM object. 3091 concurrent_mark()->post_initial_mark(); 3092 // Note that we don't actually trigger the CM thread at 3093 // this point. We do that later when we're sure that 3094 // the current thread has completed its logging output. 3095 } 3096 3097 allocate_dummy_regions(); 3098 3099 _allocator->init_mutator_alloc_region(); 3100 3101 { 3102 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3103 if (expand_bytes > 0) { 3104 size_t bytes_before = capacity(); 3105 // No need for an ergo logging here, 3106 // expansion_amount() does this when it returns a value > 0. 3107 double expand_ms; 3108 if (!expand(expand_bytes, _workers, &expand_ms)) { 3109 // We failed to expand the heap. Cannot do anything about it. 3110 } 3111 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3112 } 3113 } 3114 3115 // We redo the verification but now wrt to the new CSet which 3116 // has just got initialized after the previous CSet was freed. 3117 _cm->verify_no_cset_oops(); 3118 3119 // This timing is only used by the ergonomics to handle our pause target. 3120 // It is unclear why this should not include the full pause. We will 3121 // investigate this in CR 7178365. 3122 double sample_end_time_sec = os::elapsedTime(); 3123 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3124 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3125 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3126 3127 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3128 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3129 3130 if (VerifyRememberedSets) { 3131 log_info(gc, verify)("[Verifying RemSets after GC]"); 3132 VerifyRegionRemSetClosure v_cl; 3133 heap_region_iterate(&v_cl); 3134 } 3135 3136 _verifier->verify_after_gc(verify_type); 3137 _verifier->check_bitmaps("GC End"); 3138 3139 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3140 _ref_processor_stw->verify_no_references_recorded(); 3141 3142 // CM reference discovery will be re-enabled if necessary. 3143 } 3144 3145 #ifdef TRACESPINNING 3146 ParallelTaskTerminator::print_termination_counts(); 3147 #endif 3148 3149 gc_epilogue(false); 3150 } 3151 3152 // Print the remainder of the GC log output. 3153 if (evacuation_failed()) { 3154 log_info(gc)("To-space exhausted"); 3155 } 3156 3157 g1_policy()->print_phases(); 3158 heap_transition.print(); 3159 3160 // It is not yet to safe to tell the concurrent mark to 3161 // start as we have some optional output below. We don't want the 3162 // output from the concurrent mark thread interfering with this 3163 // logging output either. 3164 3165 _hrm->verify_optional(); 3166 _verifier->verify_region_sets_optional(); 3167 3168 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3169 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3170 3171 print_heap_after_gc(); 3172 print_heap_regions(); 3173 trace_heap_after_gc(_gc_tracer_stw); 3174 3175 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3176 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3177 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3178 // before any GC notifications are raised. 3179 g1mm()->update_sizes(); 3180 3181 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3182 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3183 _gc_timer_stw->register_gc_end(); 3184 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3185 } 3186 // It should now be safe to tell the concurrent mark thread to start 3187 // without its logging output interfering with the logging output 3188 // that came from the pause. 3189 3190 if (should_start_conc_mark) { 3191 // CAUTION: after the doConcurrentMark() call below, 3192 // the concurrent marking thread(s) could be running 3193 // concurrently with us. Make sure that anything after 3194 // this point does not assume that we are the only GC thread 3195 // running. Note: of course, the actual marking work will 3196 // not start until the safepoint itself is released in 3197 // SuspendibleThreadSet::desynchronize(). 3198 do_concurrent_mark(); 3199 } 3200 3201 return true; 3202 } 3203 3204 void G1CollectedHeap::remove_self_forwarding_pointers() { 3205 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3206 workers()->run_task(&rsfp_task); 3207 } 3208 3209 void G1CollectedHeap::restore_after_evac_failure() { 3210 double remove_self_forwards_start = os::elapsedTime(); 3211 3212 remove_self_forwarding_pointers(); 3213 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3214 _preserved_marks_set.restore(&task_executor); 3215 3216 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3217 } 3218 3219 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3220 if (!_evacuation_failed) { 3221 _evacuation_failed = true; 3222 } 3223 3224 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3225 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3226 } 3227 3228 bool G1ParEvacuateFollowersClosure::offer_termination() { 3229 EventGCPhaseParallel event; 3230 G1ParScanThreadState* const pss = par_scan_state(); 3231 start_term_time(); 3232 const bool res = terminator()->offer_termination(); 3233 end_term_time(); 3234 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3235 return res; 3236 } 3237 3238 void G1ParEvacuateFollowersClosure::do_void() { 3239 EventGCPhaseParallel event; 3240 G1ParScanThreadState* const pss = par_scan_state(); 3241 pss->trim_queue(); 3242 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3243 do { 3244 EventGCPhaseParallel event; 3245 pss->steal_and_trim_queue(queues()); 3246 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3247 } while (!offer_termination()); 3248 } 3249 3250 class G1ParTask : public AbstractGangTask { 3251 protected: 3252 G1CollectedHeap* _g1h; 3253 G1ParScanThreadStateSet* _pss; 3254 RefToScanQueueSet* _queues; 3255 G1RootProcessor* _root_processor; 3256 TaskTerminator _terminator; 3257 uint _n_workers; 3258 3259 public: 3260 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3261 : AbstractGangTask("G1 collection"), 3262 _g1h(g1h), 3263 _pss(per_thread_states), 3264 _queues(task_queues), 3265 _root_processor(root_processor), 3266 _terminator(n_workers, _queues), 3267 _n_workers(n_workers) 3268 {} 3269 3270 void work(uint worker_id) { 3271 if (worker_id >= _n_workers) return; // no work needed this round 3272 3273 double start_sec = os::elapsedTime(); 3274 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3275 3276 { 3277 ResourceMark rm; 3278 HandleMark hm; 3279 3280 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3281 3282 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3283 pss->set_ref_discoverer(rp); 3284 3285 double start_strong_roots_sec = os::elapsedTime(); 3286 3287 _root_processor->evacuate_roots(pss, worker_id); 3288 3289 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3290 // treating the nmethods visited to act as roots for concurrent marking. 3291 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3292 // objects copied by the current evacuation. 3293 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3294 3295 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3296 3297 double term_sec = 0.0; 3298 size_t evac_term_attempts = 0; 3299 { 3300 double start = os::elapsedTime(); 3301 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy); 3302 evac.do_void(); 3303 3304 evac_term_attempts = evac.term_attempts(); 3305 term_sec = evac.term_time(); 3306 double elapsed_sec = os::elapsedTime() - start; 3307 3308 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3309 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3310 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3311 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3312 } 3313 3314 assert(pss->queue_is_empty(), "should be empty"); 3315 3316 if (log_is_enabled(Debug, gc, task, stats)) { 3317 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3318 size_t lab_waste; 3319 size_t lab_undo_waste; 3320 pss->waste(lab_waste, lab_undo_waste); 3321 _g1h->print_termination_stats(worker_id, 3322 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3323 strong_roots_sec * 1000.0, /* strong roots time */ 3324 term_sec * 1000.0, /* evac term time */ 3325 evac_term_attempts, /* evac term attempts */ 3326 lab_waste, /* alloc buffer waste */ 3327 lab_undo_waste /* undo waste */ 3328 ); 3329 } 3330 3331 // Close the inner scope so that the ResourceMark and HandleMark 3332 // destructors are executed here and are included as part of the 3333 // "GC Worker Time". 3334 } 3335 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3336 } 3337 }; 3338 3339 void G1CollectedHeap::print_termination_stats_hdr() { 3340 log_debug(gc, task, stats)("GC Termination Stats"); 3341 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3342 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3343 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3344 } 3345 3346 void G1CollectedHeap::print_termination_stats(uint worker_id, 3347 double elapsed_ms, 3348 double strong_roots_ms, 3349 double term_ms, 3350 size_t term_attempts, 3351 size_t alloc_buffer_waste, 3352 size_t undo_waste) const { 3353 log_debug(gc, task, stats) 3354 ("%3d %9.2f %9.2f %6.2f " 3355 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3356 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3357 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3358 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3359 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3360 alloc_buffer_waste * HeapWordSize / K, 3361 undo_waste * HeapWordSize / K); 3362 } 3363 3364 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3365 bool class_unloading_occurred) { 3366 uint num_workers = workers()->active_workers(); 3367 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3368 workers()->run_task(&unlink_task); 3369 } 3370 3371 // Clean string dedup data structures. 3372 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3373 // record the durations of the phases. Hence the almost-copy. 3374 class G1StringDedupCleaningTask : public AbstractGangTask { 3375 BoolObjectClosure* _is_alive; 3376 OopClosure* _keep_alive; 3377 G1GCPhaseTimes* _phase_times; 3378 3379 public: 3380 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3381 OopClosure* keep_alive, 3382 G1GCPhaseTimes* phase_times) : 3383 AbstractGangTask("Partial Cleaning Task"), 3384 _is_alive(is_alive), 3385 _keep_alive(keep_alive), 3386 _phase_times(phase_times) 3387 { 3388 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3389 StringDedup::gc_prologue(true); 3390 } 3391 3392 ~G1StringDedupCleaningTask() { 3393 StringDedup::gc_epilogue(); 3394 } 3395 3396 void work(uint worker_id) { 3397 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3398 { 3399 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3400 StringDedupQueue::unlink_or_oops_do(&cl); 3401 } 3402 { 3403 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3404 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3405 } 3406 } 3407 }; 3408 3409 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3410 OopClosure* keep_alive, 3411 G1GCPhaseTimes* phase_times) { 3412 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3413 workers()->run_task(&cl); 3414 } 3415 3416 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3417 private: 3418 G1DirtyCardQueueSet* _queue; 3419 G1CollectedHeap* _g1h; 3420 public: 3421 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3422 _queue(queue), _g1h(g1h) { } 3423 3424 virtual void work(uint worker_id) { 3425 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3426 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3427 3428 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3429 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3430 3431 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3432 } 3433 }; 3434 3435 void G1CollectedHeap::redirty_logged_cards() { 3436 double redirty_logged_cards_start = os::elapsedTime(); 3437 3438 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3439 dirty_card_queue_set().reset_for_par_iteration(); 3440 workers()->run_task(&redirty_task); 3441 3442 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3443 dcq.merge_bufferlists(&dirty_card_queue_set()); 3444 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3445 3446 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3447 } 3448 3449 // Weak Reference Processing support 3450 3451 bool G1STWIsAliveClosure::do_object_b(oop p) { 3452 // An object is reachable if it is outside the collection set, 3453 // or is inside and copied. 3454 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3455 } 3456 3457 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3458 assert(obj != NULL, "must not be NULL"); 3459 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3460 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3461 // may falsely indicate that this is not the case here: however the collection set only 3462 // contains old regions when concurrent mark is not running. 3463 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3464 } 3465 3466 // Non Copying Keep Alive closure 3467 class G1KeepAliveClosure: public OopClosure { 3468 G1CollectedHeap*_g1h; 3469 public: 3470 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3471 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3472 void do_oop(oop* p) { 3473 oop obj = *p; 3474 assert(obj != NULL, "the caller should have filtered out NULL values"); 3475 3476 const InCSetState cset_state =_g1h->in_cset_state(obj); 3477 if (!cset_state.is_in_cset_or_humongous()) { 3478 return; 3479 } 3480 if (cset_state.is_in_cset()) { 3481 assert( obj->is_forwarded(), "invariant" ); 3482 *p = obj->forwardee(); 3483 } else { 3484 assert(!obj->is_forwarded(), "invariant" ); 3485 assert(cset_state.is_humongous(), 3486 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3487 _g1h->set_humongous_is_live(obj); 3488 } 3489 } 3490 }; 3491 3492 // Copying Keep Alive closure - can be called from both 3493 // serial and parallel code as long as different worker 3494 // threads utilize different G1ParScanThreadState instances 3495 // and different queues. 3496 3497 class G1CopyingKeepAliveClosure: public OopClosure { 3498 G1CollectedHeap* _g1h; 3499 G1ParScanThreadState* _par_scan_state; 3500 3501 public: 3502 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3503 G1ParScanThreadState* pss): 3504 _g1h(g1h), 3505 _par_scan_state(pss) 3506 {} 3507 3508 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3509 virtual void do_oop( oop* p) { do_oop_work(p); } 3510 3511 template <class T> void do_oop_work(T* p) { 3512 oop obj = RawAccess<>::oop_load(p); 3513 3514 if (_g1h->is_in_cset_or_humongous(obj)) { 3515 // If the referent object has been forwarded (either copied 3516 // to a new location or to itself in the event of an 3517 // evacuation failure) then we need to update the reference 3518 // field and, if both reference and referent are in the G1 3519 // heap, update the RSet for the referent. 3520 // 3521 // If the referent has not been forwarded then we have to keep 3522 // it alive by policy. Therefore we have copy the referent. 3523 // 3524 // When the queue is drained (after each phase of reference processing) 3525 // the object and it's followers will be copied, the reference field set 3526 // to point to the new location, and the RSet updated. 3527 _par_scan_state->push_on_queue(p); 3528 } 3529 } 3530 }; 3531 3532 // Serial drain queue closure. Called as the 'complete_gc' 3533 // closure for each discovered list in some of the 3534 // reference processing phases. 3535 3536 class G1STWDrainQueueClosure: public VoidClosure { 3537 protected: 3538 G1CollectedHeap* _g1h; 3539 G1ParScanThreadState* _par_scan_state; 3540 3541 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3542 3543 public: 3544 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3545 _g1h(g1h), 3546 _par_scan_state(pss) 3547 { } 3548 3549 void do_void() { 3550 G1ParScanThreadState* const pss = par_scan_state(); 3551 pss->trim_queue(); 3552 } 3553 }; 3554 3555 // Parallel Reference Processing closures 3556 3557 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3558 // processing during G1 evacuation pauses. 3559 3560 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3561 private: 3562 G1CollectedHeap* _g1h; 3563 G1ParScanThreadStateSet* _pss; 3564 RefToScanQueueSet* _queues; 3565 WorkGang* _workers; 3566 3567 public: 3568 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3569 G1ParScanThreadStateSet* per_thread_states, 3570 WorkGang* workers, 3571 RefToScanQueueSet *task_queues) : 3572 _g1h(g1h), 3573 _pss(per_thread_states), 3574 _queues(task_queues), 3575 _workers(workers) 3576 { 3577 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3578 } 3579 3580 // Executes the given task using concurrent marking worker threads. 3581 virtual void execute(ProcessTask& task, uint ergo_workers); 3582 }; 3583 3584 // Gang task for possibly parallel reference processing 3585 3586 class G1STWRefProcTaskProxy: public AbstractGangTask { 3587 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3588 ProcessTask& _proc_task; 3589 G1CollectedHeap* _g1h; 3590 G1ParScanThreadStateSet* _pss; 3591 RefToScanQueueSet* _task_queues; 3592 ParallelTaskTerminator* _terminator; 3593 3594 public: 3595 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3596 G1CollectedHeap* g1h, 3597 G1ParScanThreadStateSet* per_thread_states, 3598 RefToScanQueueSet *task_queues, 3599 ParallelTaskTerminator* terminator) : 3600 AbstractGangTask("Process reference objects in parallel"), 3601 _proc_task(proc_task), 3602 _g1h(g1h), 3603 _pss(per_thread_states), 3604 _task_queues(task_queues), 3605 _terminator(terminator) 3606 {} 3607 3608 virtual void work(uint worker_id) { 3609 // The reference processing task executed by a single worker. 3610 ResourceMark rm; 3611 HandleMark hm; 3612 3613 G1STWIsAliveClosure is_alive(_g1h); 3614 3615 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3616 pss->set_ref_discoverer(NULL); 3617 3618 // Keep alive closure. 3619 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3620 3621 // Complete GC closure 3622 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3623 3624 // Call the reference processing task's work routine. 3625 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3626 3627 // Note we cannot assert that the refs array is empty here as not all 3628 // of the processing tasks (specifically phase2 - pp2_work) execute 3629 // the complete_gc closure (which ordinarily would drain the queue) so 3630 // the queue may not be empty. 3631 } 3632 }; 3633 3634 // Driver routine for parallel reference processing. 3635 // Creates an instance of the ref processing gang 3636 // task and has the worker threads execute it. 3637 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3638 assert(_workers != NULL, "Need parallel worker threads."); 3639 3640 assert(_workers->active_workers() >= ergo_workers, 3641 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3642 ergo_workers, _workers->active_workers()); 3643 TaskTerminator terminator(ergo_workers, _queues); 3644 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3645 3646 _workers->run_task(&proc_task_proxy, ergo_workers); 3647 } 3648 3649 // End of weak reference support closures 3650 3651 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3652 double ref_proc_start = os::elapsedTime(); 3653 3654 ReferenceProcessor* rp = _ref_processor_stw; 3655 assert(rp->discovery_enabled(), "should have been enabled"); 3656 3657 // Closure to test whether a referent is alive. 3658 G1STWIsAliveClosure is_alive(this); 3659 3660 // Even when parallel reference processing is enabled, the processing 3661 // of JNI refs is serial and performed serially by the current thread 3662 // rather than by a worker. The following PSS will be used for processing 3663 // JNI refs. 3664 3665 // Use only a single queue for this PSS. 3666 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3667 pss->set_ref_discoverer(NULL); 3668 assert(pss->queue_is_empty(), "pre-condition"); 3669 3670 // Keep alive closure. 3671 G1CopyingKeepAliveClosure keep_alive(this, pss); 3672 3673 // Serial Complete GC closure 3674 G1STWDrainQueueClosure drain_queue(this, pss); 3675 3676 // Setup the soft refs policy... 3677 rp->setup_policy(false); 3678 3679 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3680 3681 ReferenceProcessorStats stats; 3682 if (!rp->processing_is_mt()) { 3683 // Serial reference processing... 3684 stats = rp->process_discovered_references(&is_alive, 3685 &keep_alive, 3686 &drain_queue, 3687 NULL, 3688 pt); 3689 } else { 3690 uint no_of_gc_workers = workers()->active_workers(); 3691 3692 // Parallel reference processing 3693 assert(no_of_gc_workers <= rp->max_num_queues(), 3694 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3695 no_of_gc_workers, rp->max_num_queues()); 3696 3697 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3698 stats = rp->process_discovered_references(&is_alive, 3699 &keep_alive, 3700 &drain_queue, 3701 &par_task_executor, 3702 pt); 3703 } 3704 3705 _gc_tracer_stw->report_gc_reference_stats(stats); 3706 3707 // We have completed copying any necessary live referent objects. 3708 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3709 3710 make_pending_list_reachable(); 3711 3712 rp->verify_no_references_recorded(); 3713 3714 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3715 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3716 } 3717 3718 void G1CollectedHeap::make_pending_list_reachable() { 3719 if (collector_state()->in_initial_mark_gc()) { 3720 oop pll_head = Universe::reference_pending_list(); 3721 if (pll_head != NULL) { 3722 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3723 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3724 } 3725 } 3726 } 3727 3728 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3729 double merge_pss_time_start = os::elapsedTime(); 3730 per_thread_states->flush(); 3731 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3732 } 3733 3734 void G1CollectedHeap::pre_evacuate_collection_set() { 3735 _expand_heap_after_alloc_failure = true; 3736 _evacuation_failed = false; 3737 3738 // Disable the hot card cache. 3739 _hot_card_cache->reset_hot_cache_claimed_index(); 3740 _hot_card_cache->set_use_cache(false); 3741 3742 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3743 _preserved_marks_set.assert_empty(); 3744 3745 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3746 3747 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3748 if (collector_state()->in_initial_mark_gc()) { 3749 double start_clear_claimed_marks = os::elapsedTime(); 3750 3751 ClassLoaderDataGraph::clear_claimed_marks(); 3752 3753 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3754 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3755 } 3756 } 3757 3758 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3759 // Should G1EvacuationFailureALot be in effect for this GC? 3760 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3761 3762 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3763 3764 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3765 3766 double start_par_time_sec = os::elapsedTime(); 3767 double end_par_time_sec; 3768 3769 { 3770 const uint n_workers = workers()->active_workers(); 3771 G1RootProcessor root_processor(this, n_workers); 3772 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3773 3774 print_termination_stats_hdr(); 3775 3776 workers()->run_task(&g1_par_task); 3777 end_par_time_sec = os::elapsedTime(); 3778 3779 // Closing the inner scope will execute the destructor 3780 // for the G1RootProcessor object. We record the current 3781 // elapsed time before closing the scope so that time 3782 // taken for the destructor is NOT included in the 3783 // reported parallel time. 3784 } 3785 3786 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3787 phase_times->record_par_time(par_time_ms); 3788 3789 double code_root_fixup_time_ms = 3790 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3791 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 3792 } 3793 3794 class G1EvacuateOptionalRegionTask : public AbstractGangTask { 3795 G1CollectedHeap* _g1h; 3796 G1ParScanThreadStateSet* _per_thread_states; 3797 G1OptionalCSet* _optional; 3798 RefToScanQueueSet* _queues; 3799 ParallelTaskTerminator _terminator; 3800 3801 Tickspan trim_ticks(G1ParScanThreadState* pss) { 3802 Tickspan copy_time = pss->trim_ticks(); 3803 pss->reset_trim_ticks(); 3804 return copy_time; 3805 } 3806 3807 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3808 G1EvacuationRootClosures* root_cls = pss->closures(); 3809 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss); 3810 3811 size_t scanned = 0; 3812 size_t claimed = 0; 3813 size_t skipped = 0; 3814 size_t used_memory = 0; 3815 3816 Ticks start = Ticks::now(); 3817 Tickspan copy_time; 3818 3819 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) { 3820 HeapRegion* hr = _optional->region_at(i); 3821 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl); 3822 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops()); 3823 copy_time += trim_ticks(pss); 3824 3825 G1ScanRSForRegionClosure scan_rs_cl(_g1h->g1_rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id); 3826 scan_rs_cl.do_heap_region(hr); 3827 copy_time += trim_ticks(pss); 3828 scanned += scan_rs_cl.cards_scanned(); 3829 claimed += scan_rs_cl.cards_claimed(); 3830 skipped += scan_rs_cl.cards_skipped(); 3831 3832 // Chunk lists for this region is no longer needed. 3833 used_memory += pss->oops_into_optional_region(hr)->used_memory(); 3834 } 3835 3836 Tickspan scan_time = (Ticks::now() - start) - copy_time; 3837 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3838 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds()); 3839 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds()); 3840 3841 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards); 3842 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards); 3843 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards); 3844 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory); 3845 } 3846 3847 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3848 Ticks start = Ticks::now(); 3849 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy); 3850 cl.do_void(); 3851 3852 Tickspan evac_time = (Ticks::now() - start); 3853 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3854 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds()); 3855 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation"); 3856 } 3857 3858 public: 3859 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h, 3860 G1ParScanThreadStateSet* per_thread_states, 3861 G1OptionalCSet* cset, 3862 RefToScanQueueSet* queues, 3863 uint n_workers) : 3864 AbstractGangTask("G1 Evacuation Optional Region Task"), 3865 _g1h(g1h), 3866 _per_thread_states(per_thread_states), 3867 _optional(cset), 3868 _queues(queues), 3869 _terminator(n_workers, _queues) { 3870 } 3871 3872 void work(uint worker_id) { 3873 ResourceMark rm; 3874 HandleMark hm; 3875 3876 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3877 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3878 3879 scan_roots(pss, worker_id); 3880 evacuate_live_objects(pss, worker_id); 3881 } 3882 }; 3883 3884 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) { 3885 class G1MarkScope : public MarkScope {}; 3886 G1MarkScope code_mark_scope; 3887 3888 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers()); 3889 workers()->run_task(&task); 3890 } 3891 3892 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3893 G1OptionalCSet optional_cset(&_collection_set, per_thread_states); 3894 if (optional_cset.is_empty()) { 3895 return; 3896 } 3897 3898 if (evacuation_failed()) { 3899 return; 3900 } 3901 3902 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3903 const double gc_start_time_ms = phase_times->cur_collection_start_sec() * 1000.0; 3904 3905 double start_time_sec = os::elapsedTime(); 3906 3907 do { 3908 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3909 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3910 3911 if (time_left_ms < 0) { 3912 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms); 3913 break; 3914 } 3915 3916 optional_cset.prepare_evacuation(time_left_ms * _g1_policy->optional_evacuation_fraction()); 3917 if (optional_cset.prepare_failed()) { 3918 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms); 3919 break; 3920 } 3921 3922 evacuate_optional_regions(per_thread_states, &optional_cset); 3923 3924 optional_cset.complete_evacuation(); 3925 if (optional_cset.evacuation_failed()) { 3926 break; 3927 } 3928 } while (!optional_cset.is_empty()); 3929 3930 phase_times->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0); 3931 } 3932 3933 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3934 // Also cleans the card table from temporary duplicate detection information used 3935 // during UpdateRS/ScanRS. 3936 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 3937 3938 // Process any discovered reference objects - we have 3939 // to do this _before_ we retire the GC alloc regions 3940 // as we may have to copy some 'reachable' referent 3941 // objects (and their reachable sub-graphs) that were 3942 // not copied during the pause. 3943 process_discovered_references(per_thread_states); 3944 3945 G1STWIsAliveClosure is_alive(this); 3946 G1KeepAliveClosure keep_alive(this); 3947 3948 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3949 g1_policy()->phase_times()->weak_phase_times()); 3950 3951 if (G1StringDedup::is_enabled()) { 3952 double string_dedup_time_ms = os::elapsedTime(); 3953 3954 string_dedup_cleaning(&is_alive, &keep_alive, g1_policy()->phase_times()); 3955 3956 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3957 g1_policy()->phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3958 } 3959 3960 if (evacuation_failed()) { 3961 restore_after_evac_failure(); 3962 3963 // Reset the G1EvacuationFailureALot counters and flags 3964 // Note: the values are reset only when an actual 3965 // evacuation failure occurs. 3966 NOT_PRODUCT(reset_evacuation_should_fail();) 3967 } 3968 3969 _preserved_marks_set.assert_empty(); 3970 3971 _allocator->release_gc_alloc_regions(evacuation_info); 3972 3973 merge_per_thread_state_info(per_thread_states); 3974 3975 // Reset and re-enable the hot card cache. 3976 // Note the counts for the cards in the regions in the 3977 // collection set are reset when the collection set is freed. 3978 _hot_card_cache->reset_hot_cache(); 3979 _hot_card_cache->set_use_cache(true); 3980 3981 purge_code_root_memory(); 3982 3983 redirty_logged_cards(); 3984 #if COMPILER2_OR_JVMCI 3985 double start = os::elapsedTime(); 3986 DerivedPointerTable::update_pointers(); 3987 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3988 #endif 3989 g1_policy()->print_age_table(); 3990 } 3991 3992 void G1CollectedHeap::record_obj_copy_mem_stats() { 3993 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3994 3995 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3996 create_g1_evac_summary(&_old_evac_stats)); 3997 } 3998 3999 void G1CollectedHeap::free_region(HeapRegion* hr, 4000 FreeRegionList* free_list, 4001 bool skip_remset, 4002 bool skip_hot_card_cache, 4003 bool locked) { 4004 assert(!hr->is_free(), "the region should not be free"); 4005 assert(!hr->is_empty(), "the region should not be empty"); 4006 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 4007 assert(free_list != NULL, "pre-condition"); 4008 4009 if (G1VerifyBitmaps) { 4010 MemRegion mr(hr->bottom(), hr->end()); 4011 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4012 } 4013 4014 // Clear the card counts for this region. 4015 // Note: we only need to do this if the region is not young 4016 // (since we don't refine cards in young regions). 4017 if (!skip_hot_card_cache && !hr->is_young()) { 4018 _hot_card_cache->reset_card_counts(hr); 4019 } 4020 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4021 _g1_policy->remset_tracker()->update_at_free(hr); 4022 free_list->add_ordered(hr); 4023 } 4024 4025 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4026 FreeRegionList* free_list) { 4027 assert(hr->is_humongous(), "this is only for humongous regions"); 4028 assert(free_list != NULL, "pre-condition"); 4029 hr->clear_humongous(); 4030 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 4031 } 4032 4033 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4034 const uint humongous_regions_removed) { 4035 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4036 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4037 _old_set.bulk_remove(old_regions_removed); 4038 _humongous_set.bulk_remove(humongous_regions_removed); 4039 } 4040 4041 } 4042 4043 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4044 assert(list != NULL, "list can't be null"); 4045 if (!list->is_empty()) { 4046 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4047 _hrm->insert_list_into_free_list(list); 4048 } 4049 } 4050 4051 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4052 decrease_used(bytes); 4053 } 4054 4055 class G1FreeCollectionSetTask : public AbstractGangTask { 4056 private: 4057 4058 // Closure applied to all regions in the collection set to do work that needs to 4059 // be done serially in a single thread. 4060 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4061 private: 4062 G1EvacuationInfo* _evacuation_info; 4063 const size_t* _surviving_young_words; 4064 4065 // Bytes used in successfully evacuated regions before the evacuation. 4066 size_t _before_used_bytes; 4067 // Bytes used in unsucessfully evacuated regions before the evacuation 4068 size_t _after_used_bytes; 4069 4070 size_t _bytes_allocated_in_old_since_last_gc; 4071 4072 size_t _failure_used_words; 4073 size_t _failure_waste_words; 4074 4075 FreeRegionList _local_free_list; 4076 public: 4077 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4078 HeapRegionClosure(), 4079 _evacuation_info(evacuation_info), 4080 _surviving_young_words(surviving_young_words), 4081 _before_used_bytes(0), 4082 _after_used_bytes(0), 4083 _bytes_allocated_in_old_since_last_gc(0), 4084 _failure_used_words(0), 4085 _failure_waste_words(0), 4086 _local_free_list("Local Region List for CSet Freeing") { 4087 } 4088 4089 virtual bool do_heap_region(HeapRegion* r) { 4090 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4091 4092 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4093 g1h->clear_in_cset(r); 4094 4095 if (r->is_young()) { 4096 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4097 "Young index %d is wrong for region %u of type %s with %u young regions", 4098 r->young_index_in_cset(), 4099 r->hrm_index(), 4100 r->get_type_str(), 4101 g1h->collection_set()->young_region_length()); 4102 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4103 r->record_surv_words_in_group(words_survived); 4104 } 4105 4106 if (!r->evacuation_failed()) { 4107 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4108 _before_used_bytes += r->used(); 4109 g1h->free_region(r, 4110 &_local_free_list, 4111 true, /* skip_remset */ 4112 true, /* skip_hot_card_cache */ 4113 true /* locked */); 4114 } else { 4115 r->uninstall_surv_rate_group(); 4116 r->set_young_index_in_cset(-1); 4117 r->set_evacuation_failed(false); 4118 // When moving a young gen region to old gen, we "allocate" that whole region 4119 // there. This is in addition to any already evacuated objects. Notify the 4120 // policy about that. 4121 // Old gen regions do not cause an additional allocation: both the objects 4122 // still in the region and the ones already moved are accounted for elsewhere. 4123 if (r->is_young()) { 4124 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4125 } 4126 // The region is now considered to be old. 4127 r->set_old(); 4128 // Do some allocation statistics accounting. Regions that failed evacuation 4129 // are always made old, so there is no need to update anything in the young 4130 // gen statistics, but we need to update old gen statistics. 4131 size_t used_words = r->marked_bytes() / HeapWordSize; 4132 4133 _failure_used_words += used_words; 4134 _failure_waste_words += HeapRegion::GrainWords - used_words; 4135 4136 g1h->old_set_add(r); 4137 _after_used_bytes += r->used(); 4138 } 4139 return false; 4140 } 4141 4142 void complete_work() { 4143 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4144 4145 _evacuation_info->set_regions_freed(_local_free_list.length()); 4146 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4147 4148 g1h->prepend_to_freelist(&_local_free_list); 4149 g1h->decrement_summary_bytes(_before_used_bytes); 4150 4151 G1Policy* policy = g1h->g1_policy(); 4152 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4153 4154 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4155 } 4156 }; 4157 4158 G1CollectionSet* _collection_set; 4159 G1SerialFreeCollectionSetClosure _cl; 4160 const size_t* _surviving_young_words; 4161 4162 size_t _rs_lengths; 4163 4164 volatile jint _serial_work_claim; 4165 4166 struct WorkItem { 4167 uint region_idx; 4168 bool is_young; 4169 bool evacuation_failed; 4170 4171 WorkItem(HeapRegion* r) { 4172 region_idx = r->hrm_index(); 4173 is_young = r->is_young(); 4174 evacuation_failed = r->evacuation_failed(); 4175 } 4176 }; 4177 4178 volatile size_t _parallel_work_claim; 4179 size_t _num_work_items; 4180 WorkItem* _work_items; 4181 4182 void do_serial_work() { 4183 // Need to grab the lock to be allowed to modify the old region list. 4184 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4185 _collection_set->iterate(&_cl); 4186 } 4187 4188 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4189 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4190 4191 HeapRegion* r = g1h->region_at(region_idx); 4192 assert(!g1h->is_on_master_free_list(r), "sanity"); 4193 4194 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4195 4196 if (!is_young) { 4197 g1h->_hot_card_cache->reset_card_counts(r); 4198 } 4199 4200 if (!evacuation_failed) { 4201 r->rem_set()->clear_locked(); 4202 } 4203 } 4204 4205 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4206 private: 4207 size_t _cur_idx; 4208 WorkItem* _work_items; 4209 public: 4210 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4211 4212 virtual bool do_heap_region(HeapRegion* r) { 4213 _work_items[_cur_idx++] = WorkItem(r); 4214 return false; 4215 } 4216 }; 4217 4218 void prepare_work() { 4219 G1PrepareFreeCollectionSetClosure cl(_work_items); 4220 _collection_set->iterate(&cl); 4221 } 4222 4223 void complete_work() { 4224 _cl.complete_work(); 4225 4226 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4227 policy->record_max_rs_lengths(_rs_lengths); 4228 policy->cset_regions_freed(); 4229 } 4230 public: 4231 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4232 AbstractGangTask("G1 Free Collection Set"), 4233 _collection_set(collection_set), 4234 _cl(evacuation_info, surviving_young_words), 4235 _surviving_young_words(surviving_young_words), 4236 _rs_lengths(0), 4237 _serial_work_claim(0), 4238 _parallel_work_claim(0), 4239 _num_work_items(collection_set->region_length()), 4240 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4241 prepare_work(); 4242 } 4243 4244 ~G1FreeCollectionSetTask() { 4245 complete_work(); 4246 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4247 } 4248 4249 // Chunk size for work distribution. The chosen value has been determined experimentally 4250 // to be a good tradeoff between overhead and achievable parallelism. 4251 static uint chunk_size() { return 32; } 4252 4253 virtual void work(uint worker_id) { 4254 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4255 4256 // Claim serial work. 4257 if (_serial_work_claim == 0) { 4258 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4259 if (value == 0) { 4260 double serial_time = os::elapsedTime(); 4261 do_serial_work(); 4262 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4263 } 4264 } 4265 4266 // Start parallel work. 4267 double young_time = 0.0; 4268 bool has_young_time = false; 4269 double non_young_time = 0.0; 4270 bool has_non_young_time = false; 4271 4272 while (true) { 4273 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4274 size_t cur = end - chunk_size(); 4275 4276 if (cur >= _num_work_items) { 4277 break; 4278 } 4279 4280 EventGCPhaseParallel event; 4281 double start_time = os::elapsedTime(); 4282 4283 end = MIN2(end, _num_work_items); 4284 4285 for (; cur < end; cur++) { 4286 bool is_young = _work_items[cur].is_young; 4287 4288 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4289 4290 double end_time = os::elapsedTime(); 4291 double time_taken = end_time - start_time; 4292 if (is_young) { 4293 young_time += time_taken; 4294 has_young_time = true; 4295 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4296 } else { 4297 non_young_time += time_taken; 4298 has_non_young_time = true; 4299 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4300 } 4301 start_time = end_time; 4302 } 4303 } 4304 4305 if (has_young_time) { 4306 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4307 } 4308 if (has_non_young_time) { 4309 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4310 } 4311 } 4312 }; 4313 4314 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4315 _eden.clear(); 4316 4317 double free_cset_start_time = os::elapsedTime(); 4318 4319 { 4320 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4321 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4322 4323 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4324 4325 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4326 cl.name(), 4327 num_workers, 4328 _collection_set.region_length()); 4329 workers()->run_task(&cl, num_workers); 4330 } 4331 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4332 4333 collection_set->clear(); 4334 } 4335 4336 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4337 private: 4338 FreeRegionList* _free_region_list; 4339 HeapRegionSet* _proxy_set; 4340 uint _humongous_objects_reclaimed; 4341 uint _humongous_regions_reclaimed; 4342 size_t _freed_bytes; 4343 public: 4344 4345 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4346 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4347 } 4348 4349 virtual bool do_heap_region(HeapRegion* r) { 4350 if (!r->is_starts_humongous()) { 4351 return false; 4352 } 4353 4354 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4355 4356 oop obj = (oop)r->bottom(); 4357 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4358 4359 // The following checks whether the humongous object is live are sufficient. 4360 // The main additional check (in addition to having a reference from the roots 4361 // or the young gen) is whether the humongous object has a remembered set entry. 4362 // 4363 // A humongous object cannot be live if there is no remembered set for it 4364 // because: 4365 // - there can be no references from within humongous starts regions referencing 4366 // the object because we never allocate other objects into them. 4367 // (I.e. there are no intra-region references that may be missed by the 4368 // remembered set) 4369 // - as soon there is a remembered set entry to the humongous starts region 4370 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4371 // until the end of a concurrent mark. 4372 // 4373 // It is not required to check whether the object has been found dead by marking 4374 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4375 // all objects allocated during that time are considered live. 4376 // SATB marking is even more conservative than the remembered set. 4377 // So if at this point in the collection there is no remembered set entry, 4378 // nobody has a reference to it. 4379 // At the start of collection we flush all refinement logs, and remembered sets 4380 // are completely up-to-date wrt to references to the humongous object. 4381 // 4382 // Other implementation considerations: 4383 // - never consider object arrays at this time because they would pose 4384 // considerable effort for cleaning up the the remembered sets. This is 4385 // required because stale remembered sets might reference locations that 4386 // are currently allocated into. 4387 uint region_idx = r->hrm_index(); 4388 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4389 !r->rem_set()->is_empty()) { 4390 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", 4391 region_idx, 4392 (size_t)obj->size() * HeapWordSize, 4393 p2i(r->bottom()), 4394 r->rem_set()->occupied(), 4395 r->rem_set()->strong_code_roots_list_length(), 4396 next_bitmap->is_marked(r->bottom()), 4397 g1h->is_humongous_reclaim_candidate(region_idx), 4398 obj->is_typeArray() 4399 ); 4400 return false; 4401 } 4402 4403 guarantee(obj->is_typeArray(), 4404 "Only eagerly reclaiming type arrays is supported, but the object " 4405 PTR_FORMAT " is not.", p2i(r->bottom())); 4406 4407 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", 4408 region_idx, 4409 (size_t)obj->size() * HeapWordSize, 4410 p2i(r->bottom()), 4411 r->rem_set()->occupied(), 4412 r->rem_set()->strong_code_roots_list_length(), 4413 next_bitmap->is_marked(r->bottom()), 4414 g1h->is_humongous_reclaim_candidate(region_idx), 4415 obj->is_typeArray() 4416 ); 4417 4418 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4419 cm->humongous_object_eagerly_reclaimed(r); 4420 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4421 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4422 region_idx, 4423 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4424 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4425 _humongous_objects_reclaimed++; 4426 do { 4427 HeapRegion* next = g1h->next_region_in_humongous(r); 4428 _freed_bytes += r->used(); 4429 r->set_containing_set(NULL); 4430 _humongous_regions_reclaimed++; 4431 g1h->free_humongous_region(r, _free_region_list); 4432 r = next; 4433 } while (r != NULL); 4434 4435 return false; 4436 } 4437 4438 uint humongous_objects_reclaimed() { 4439 return _humongous_objects_reclaimed; 4440 } 4441 4442 uint humongous_regions_reclaimed() { 4443 return _humongous_regions_reclaimed; 4444 } 4445 4446 size_t bytes_freed() const { 4447 return _freed_bytes; 4448 } 4449 }; 4450 4451 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4452 assert_at_safepoint_on_vm_thread(); 4453 4454 if (!G1EagerReclaimHumongousObjects || 4455 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4456 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4457 return; 4458 } 4459 4460 double start_time = os::elapsedTime(); 4461 4462 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4463 4464 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4465 heap_region_iterate(&cl); 4466 4467 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4468 4469 G1HRPrinter* hrp = hr_printer(); 4470 if (hrp->is_active()) { 4471 FreeRegionListIterator iter(&local_cleanup_list); 4472 while (iter.more_available()) { 4473 HeapRegion* hr = iter.get_next(); 4474 hrp->cleanup(hr); 4475 } 4476 } 4477 4478 prepend_to_freelist(&local_cleanup_list); 4479 decrement_summary_bytes(cl.bytes_freed()); 4480 4481 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4482 cl.humongous_objects_reclaimed()); 4483 } 4484 4485 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4486 public: 4487 virtual bool do_heap_region(HeapRegion* r) { 4488 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4489 G1CollectedHeap::heap()->clear_in_cset(r); 4490 r->set_young_index_in_cset(-1); 4491 return false; 4492 } 4493 }; 4494 4495 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4496 G1AbandonCollectionSetClosure cl; 4497 collection_set->iterate(&cl); 4498 4499 collection_set->clear(); 4500 collection_set->stop_incremental_building(); 4501 } 4502 4503 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4504 return _allocator->is_retained_old_region(hr); 4505 } 4506 4507 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4508 _eden.add(hr); 4509 _g1_policy->set_region_eden(hr); 4510 } 4511 4512 #ifdef ASSERT 4513 4514 class NoYoungRegionsClosure: public HeapRegionClosure { 4515 private: 4516 bool _success; 4517 public: 4518 NoYoungRegionsClosure() : _success(true) { } 4519 bool do_heap_region(HeapRegion* r) { 4520 if (r->is_young()) { 4521 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4522 p2i(r->bottom()), p2i(r->end())); 4523 _success = false; 4524 } 4525 return false; 4526 } 4527 bool success() { return _success; } 4528 }; 4529 4530 bool G1CollectedHeap::check_young_list_empty() { 4531 bool ret = (young_regions_count() == 0); 4532 4533 NoYoungRegionsClosure closure; 4534 heap_region_iterate(&closure); 4535 ret = ret && closure.success(); 4536 4537 return ret; 4538 } 4539 4540 #endif // ASSERT 4541 4542 class TearDownRegionSetsClosure : public HeapRegionClosure { 4543 HeapRegionSet *_old_set; 4544 4545 public: 4546 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4547 4548 bool do_heap_region(HeapRegion* r) { 4549 if (r->is_old()) { 4550 _old_set->remove(r); 4551 } else if(r->is_young()) { 4552 r->uninstall_surv_rate_group(); 4553 } else { 4554 // We ignore free regions, we'll empty the free list afterwards. 4555 // We ignore humongous and archive regions, we're not tearing down these 4556 // sets. 4557 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4558 "it cannot be another type"); 4559 } 4560 return false; 4561 } 4562 4563 ~TearDownRegionSetsClosure() { 4564 assert(_old_set->is_empty(), "post-condition"); 4565 } 4566 }; 4567 4568 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4569 assert_at_safepoint_on_vm_thread(); 4570 4571 if (!free_list_only) { 4572 TearDownRegionSetsClosure cl(&_old_set); 4573 heap_region_iterate(&cl); 4574 4575 // Note that emptying the _young_list is postponed and instead done as 4576 // the first step when rebuilding the regions sets again. The reason for 4577 // this is that during a full GC string deduplication needs to know if 4578 // a collected region was young or old when the full GC was initiated. 4579 } 4580 _hrm->remove_all_free_regions(); 4581 } 4582 4583 void G1CollectedHeap::increase_used(size_t bytes) { 4584 _summary_bytes_used += bytes; 4585 } 4586 4587 void G1CollectedHeap::decrease_used(size_t bytes) { 4588 assert(_summary_bytes_used >= bytes, 4589 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4590 _summary_bytes_used, bytes); 4591 _summary_bytes_used -= bytes; 4592 } 4593 4594 void G1CollectedHeap::set_used(size_t bytes) { 4595 _summary_bytes_used = bytes; 4596 } 4597 4598 class RebuildRegionSetsClosure : public HeapRegionClosure { 4599 private: 4600 bool _free_list_only; 4601 4602 HeapRegionSet* _old_set; 4603 HeapRegionManager* _hrm; 4604 4605 size_t _total_used; 4606 4607 public: 4608 RebuildRegionSetsClosure(bool free_list_only, 4609 HeapRegionSet* old_set, 4610 HeapRegionManager* hrm) : 4611 _free_list_only(free_list_only), 4612 _old_set(old_set), _hrm(hrm), _total_used(0) { 4613 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4614 if (!free_list_only) { 4615 assert(_old_set->is_empty(), "pre-condition"); 4616 } 4617 } 4618 4619 bool do_heap_region(HeapRegion* r) { 4620 if (r->is_empty()) { 4621 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4622 // Add free regions to the free list 4623 r->set_free(); 4624 _hrm->insert_into_free_list(r); 4625 } else if (!_free_list_only) { 4626 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4627 4628 if (r->is_archive() || r->is_humongous()) { 4629 // We ignore archive and humongous regions. We left these sets unchanged. 4630 } else { 4631 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4632 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4633 r->move_to_old(); 4634 _old_set->add(r); 4635 } 4636 _total_used += r->used(); 4637 } 4638 4639 return false; 4640 } 4641 4642 size_t total_used() { 4643 return _total_used; 4644 } 4645 }; 4646 4647 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4648 assert_at_safepoint_on_vm_thread(); 4649 4650 if (!free_list_only) { 4651 _eden.clear(); 4652 _survivor.clear(); 4653 } 4654 4655 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4656 heap_region_iterate(&cl); 4657 4658 if (!free_list_only) { 4659 set_used(cl.total_used()); 4660 if (_archive_allocator != NULL) { 4661 _archive_allocator->clear_used(); 4662 } 4663 } 4664 assert(used() == recalculate_used(), 4665 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4666 used(), recalculate_used()); 4667 } 4668 4669 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4670 HeapRegion* hr = heap_region_containing(p); 4671 return hr->is_in(p); 4672 } 4673 4674 // Methods for the mutator alloc region 4675 4676 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4677 bool force) { 4678 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4679 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4680 if (force || should_allocate) { 4681 HeapRegion* new_alloc_region = new_region(word_size, 4682 HeapRegionType::Eden, 4683 false /* do_expand */); 4684 if (new_alloc_region != NULL) { 4685 set_region_short_lived_locked(new_alloc_region); 4686 _hr_printer.alloc(new_alloc_region, !should_allocate); 4687 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4688 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4689 return new_alloc_region; 4690 } 4691 } 4692 return NULL; 4693 } 4694 4695 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4696 size_t allocated_bytes) { 4697 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4698 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4699 4700 collection_set()->add_eden_region(alloc_region); 4701 increase_used(allocated_bytes); 4702 _hr_printer.retire(alloc_region); 4703 // We update the eden sizes here, when the region is retired, 4704 // instead of when it's allocated, since this is the point that its 4705 // used space has been recorded in _summary_bytes_used. 4706 g1mm()->update_eden_size(); 4707 } 4708 4709 // Methods for the GC alloc regions 4710 4711 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4712 if (dest.is_old()) { 4713 return true; 4714 } else { 4715 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4716 } 4717 } 4718 4719 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4720 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4721 4722 if (!has_more_regions(dest)) { 4723 return NULL; 4724 } 4725 4726 HeapRegionType type; 4727 if (dest.is_young()) { 4728 type = HeapRegionType::Survivor; 4729 } else { 4730 type = HeapRegionType::Old; 4731 } 4732 4733 HeapRegion* new_alloc_region = new_region(word_size, 4734 type, 4735 true /* do_expand */); 4736 4737 if (new_alloc_region != NULL) { 4738 if (type.is_survivor()) { 4739 new_alloc_region->set_survivor(); 4740 _survivor.add(new_alloc_region); 4741 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4742 } else { 4743 new_alloc_region->set_old(); 4744 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4745 } 4746 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4747 _hr_printer.alloc(new_alloc_region); 4748 return new_alloc_region; 4749 } 4750 return NULL; 4751 } 4752 4753 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4754 size_t allocated_bytes, 4755 InCSetState dest) { 4756 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4757 if (dest.is_old()) { 4758 old_set_add(alloc_region); 4759 } 4760 4761 bool const during_im = collector_state()->in_initial_mark_gc(); 4762 if (during_im && allocated_bytes > 0) { 4763 _cm->root_regions()->add(alloc_region); 4764 } 4765 _hr_printer.retire(alloc_region); 4766 } 4767 4768 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4769 bool expanded = false; 4770 uint index = _hrm->find_highest_free(&expanded); 4771 4772 if (index != G1_NO_HRM_INDEX) { 4773 if (expanded) { 4774 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4775 HeapRegion::GrainWords * HeapWordSize); 4776 } 4777 _hrm->allocate_free_regions_starting_at(index, 1); 4778 return region_at(index); 4779 } 4780 return NULL; 4781 } 4782 4783 // Optimized nmethod scanning 4784 4785 class RegisterNMethodOopClosure: public OopClosure { 4786 G1CollectedHeap* _g1h; 4787 nmethod* _nm; 4788 4789 template <class T> void do_oop_work(T* p) { 4790 T heap_oop = RawAccess<>::oop_load(p); 4791 if (!CompressedOops::is_null(heap_oop)) { 4792 oop obj = CompressedOops::decode_not_null(heap_oop); 4793 HeapRegion* hr = _g1h->heap_region_containing(obj); 4794 assert(!hr->is_continues_humongous(), 4795 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4796 " starting at " HR_FORMAT, 4797 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4798 4799 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4800 hr->add_strong_code_root_locked(_nm); 4801 } 4802 } 4803 4804 public: 4805 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4806 _g1h(g1h), _nm(nm) {} 4807 4808 void do_oop(oop* p) { do_oop_work(p); } 4809 void do_oop(narrowOop* p) { do_oop_work(p); } 4810 }; 4811 4812 class UnregisterNMethodOopClosure: public OopClosure { 4813 G1CollectedHeap* _g1h; 4814 nmethod* _nm; 4815 4816 template <class T> void do_oop_work(T* p) { 4817 T heap_oop = RawAccess<>::oop_load(p); 4818 if (!CompressedOops::is_null(heap_oop)) { 4819 oop obj = CompressedOops::decode_not_null(heap_oop); 4820 HeapRegion* hr = _g1h->heap_region_containing(obj); 4821 assert(!hr->is_continues_humongous(), 4822 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4823 " starting at " HR_FORMAT, 4824 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4825 4826 hr->remove_strong_code_root(_nm); 4827 } 4828 } 4829 4830 public: 4831 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4832 _g1h(g1h), _nm(nm) {} 4833 4834 void do_oop(oop* p) { do_oop_work(p); } 4835 void do_oop(narrowOop* p) { do_oop_work(p); } 4836 }; 4837 4838 // Returns true if the reference points to an object that 4839 // can move in an incremental collection. 4840 bool G1CollectedHeap::is_scavengable(oop obj) { 4841 HeapRegion* hr = heap_region_containing(obj); 4842 return !hr->is_pinned(); 4843 } 4844 4845 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4846 guarantee(nm != NULL, "sanity"); 4847 RegisterNMethodOopClosure reg_cl(this, nm); 4848 nm->oops_do(®_cl); 4849 } 4850 4851 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4852 guarantee(nm != NULL, "sanity"); 4853 UnregisterNMethodOopClosure reg_cl(this, nm); 4854 nm->oops_do(®_cl, true); 4855 } 4856 4857 void G1CollectedHeap::purge_code_root_memory() { 4858 double purge_start = os::elapsedTime(); 4859 G1CodeRootSet::purge(); 4860 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4861 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4862 } 4863 4864 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4865 G1CollectedHeap* _g1h; 4866 4867 public: 4868 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4869 _g1h(g1h) {} 4870 4871 void do_code_blob(CodeBlob* cb) { 4872 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4873 if (nm == NULL) { 4874 return; 4875 } 4876 4877 if (ScavengeRootsInCode) { 4878 _g1h->register_nmethod(nm); 4879 } 4880 } 4881 }; 4882 4883 void G1CollectedHeap::rebuild_strong_code_roots() { 4884 RebuildStrongCodeRootClosure blob_cl(this); 4885 CodeCache::blobs_do(&blob_cl); 4886 } 4887 4888 void G1CollectedHeap::initialize_serviceability() { 4889 _g1mm->initialize_serviceability(); 4890 } 4891 4892 MemoryUsage G1CollectedHeap::memory_usage() { 4893 return _g1mm->memory_usage(); 4894 } 4895 4896 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4897 return _g1mm->memory_managers(); 4898 } 4899 4900 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4901 return _g1mm->memory_pools(); 4902 }