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 1681 // process_completed_buffers_threshold and max_completed_buffers are updated 1682 // later, based on the concurrent refinement object. 1683 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1684 &bs->dirty_card_queue_buffer_allocator(), 1685 Shared_DirtyCardQ_lock, 1686 true); // init_free_ids 1687 1688 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1689 &bs->dirty_card_queue_buffer_allocator(), 1690 Shared_DirtyCardQ_lock); 1691 1692 // Create the hot card cache. 1693 _hot_card_cache = new G1HotCardCache(this); 1694 1695 // Carve out the G1 part of the heap. 1696 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1697 size_t page_size = actual_reserved_page_size(heap_rs); 1698 G1RegionToSpaceMapper* heap_storage = 1699 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1700 g1_rs.size(), 1701 page_size, 1702 HeapRegion::GrainBytes, 1703 1, 1704 mtJavaHeap); 1705 if(heap_storage == NULL) { 1706 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1707 return JNI_ERR; 1708 } 1709 1710 os::trace_page_sizes("Heap", 1711 collector_policy()->min_heap_byte_size(), 1712 max_byte_size, 1713 page_size, 1714 heap_rs.base(), 1715 heap_rs.size()); 1716 heap_storage->set_mapping_changed_listener(&_listener); 1717 1718 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1719 G1RegionToSpaceMapper* bot_storage = 1720 create_aux_memory_mapper("Block Offset Table", 1721 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1722 G1BlockOffsetTable::heap_map_factor()); 1723 1724 G1RegionToSpaceMapper* cardtable_storage = 1725 create_aux_memory_mapper("Card Table", 1726 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1727 G1CardTable::heap_map_factor()); 1728 1729 G1RegionToSpaceMapper* card_counts_storage = 1730 create_aux_memory_mapper("Card Counts Table", 1731 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1732 G1CardCounts::heap_map_factor()); 1733 1734 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1735 G1RegionToSpaceMapper* prev_bitmap_storage = 1736 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1737 G1RegionToSpaceMapper* next_bitmap_storage = 1738 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1739 1740 _hrm = HeapRegionManager::create_manager(this, g1_collector_policy()); 1741 1742 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1743 _card_table->initialize(cardtable_storage); 1744 // Do later initialization work for concurrent refinement. 1745 _hot_card_cache->initialize(card_counts_storage); 1746 1747 // 6843694 - ensure that the maximum region index can fit 1748 // in the remembered set structures. 1749 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1750 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1751 1752 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1753 // start within the first card. 1754 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1755 // Also create a G1 rem set. 1756 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1757 _g1_rem_set->initialize(max_reserved_capacity(), max_regions()); 1758 1759 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1760 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1761 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1762 "too many cards per region"); 1763 1764 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1765 1766 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1767 1768 { 1769 HeapWord* start = _hrm->reserved().start(); 1770 HeapWord* end = _hrm->reserved().end(); 1771 size_t granularity = HeapRegion::GrainBytes; 1772 1773 _in_cset_fast_test.initialize(start, end, granularity); 1774 _humongous_reclaim_candidates.initialize(start, end, granularity); 1775 } 1776 1777 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1778 true /* are_GC_task_threads */, 1779 false /* are_ConcurrentGC_threads */); 1780 if (_workers == NULL) { 1781 return JNI_ENOMEM; 1782 } 1783 _workers->initialize_workers(); 1784 1785 // Create the G1ConcurrentMark data structure and thread. 1786 // (Must do this late, so that "max_regions" is defined.) 1787 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1788 if (_cm == NULL || !_cm->completed_initialization()) { 1789 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1790 return JNI_ENOMEM; 1791 } 1792 _cm_thread = _cm->cm_thread(); 1793 1794 // Now expand into the initial heap size. 1795 if (!expand(init_byte_size, _workers)) { 1796 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1797 return JNI_ENOMEM; 1798 } 1799 1800 // Perform any initialization actions delegated to the policy. 1801 g1_policy()->init(this, &_collection_set); 1802 1803 jint ecode = initialize_concurrent_refinement(); 1804 if (ecode != JNI_OK) { 1805 return ecode; 1806 } 1807 1808 ecode = initialize_young_gen_sampling_thread(); 1809 if (ecode != JNI_OK) { 1810 return ecode; 1811 } 1812 1813 { 1814 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1815 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone()); 1816 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone()); 1817 } 1818 1819 // Here we allocate the dummy HeapRegion that is required by the 1820 // G1AllocRegion class. 1821 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1822 1823 // We'll re-use the same region whether the alloc region will 1824 // require BOT updates or not and, if it doesn't, then a non-young 1825 // region will complain that it cannot support allocations without 1826 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1827 dummy_region->set_eden(); 1828 // Make sure it's full. 1829 dummy_region->set_top(dummy_region->end()); 1830 G1AllocRegion::setup(this, dummy_region); 1831 1832 _allocator->init_mutator_alloc_region(); 1833 1834 // Do create of the monitoring and management support so that 1835 // values in the heap have been properly initialized. 1836 _g1mm = new G1MonitoringSupport(this); 1837 1838 G1StringDedup::initialize(); 1839 1840 _preserved_marks_set.init(ParallelGCThreads); 1841 1842 _collection_set.initialize(max_regions()); 1843 1844 return JNI_OK; 1845 } 1846 1847 void G1CollectedHeap::stop() { 1848 // Stop all concurrent threads. We do this to make sure these threads 1849 // do not continue to execute and access resources (e.g. logging) 1850 // that are destroyed during shutdown. 1851 _cr->stop(); 1852 _young_gen_sampling_thread->stop(); 1853 _cm_thread->stop(); 1854 if (G1StringDedup::is_enabled()) { 1855 G1StringDedup::stop(); 1856 } 1857 } 1858 1859 void G1CollectedHeap::safepoint_synchronize_begin() { 1860 SuspendibleThreadSet::synchronize(); 1861 } 1862 1863 void G1CollectedHeap::safepoint_synchronize_end() { 1864 SuspendibleThreadSet::desynchronize(); 1865 } 1866 1867 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1868 return HeapRegion::max_region_size(); 1869 } 1870 1871 void G1CollectedHeap::post_initialize() { 1872 CollectedHeap::post_initialize(); 1873 ref_processing_init(); 1874 } 1875 1876 void G1CollectedHeap::ref_processing_init() { 1877 // Reference processing in G1 currently works as follows: 1878 // 1879 // * There are two reference processor instances. One is 1880 // used to record and process discovered references 1881 // during concurrent marking; the other is used to 1882 // record and process references during STW pauses 1883 // (both full and incremental). 1884 // * Both ref processors need to 'span' the entire heap as 1885 // the regions in the collection set may be dotted around. 1886 // 1887 // * For the concurrent marking ref processor: 1888 // * Reference discovery is enabled at initial marking. 1889 // * Reference discovery is disabled and the discovered 1890 // references processed etc during remarking. 1891 // * Reference discovery is MT (see below). 1892 // * Reference discovery requires a barrier (see below). 1893 // * Reference processing may or may not be MT 1894 // (depending on the value of ParallelRefProcEnabled 1895 // and ParallelGCThreads). 1896 // * A full GC disables reference discovery by the CM 1897 // ref processor and abandons any entries on it's 1898 // discovered lists. 1899 // 1900 // * For the STW processor: 1901 // * Non MT discovery is enabled at the start of a full GC. 1902 // * Processing and enqueueing during a full GC is non-MT. 1903 // * During a full GC, references are processed after marking. 1904 // 1905 // * Discovery (may or may not be MT) is enabled at the start 1906 // of an incremental evacuation pause. 1907 // * References are processed near the end of a STW evacuation pause. 1908 // * For both types of GC: 1909 // * Discovery is atomic - i.e. not concurrent. 1910 // * Reference discovery will not need a barrier. 1911 1912 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1913 1914 // Concurrent Mark ref processor 1915 _ref_processor_cm = 1916 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1917 mt_processing, // mt processing 1918 ParallelGCThreads, // degree of mt processing 1919 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1920 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1921 false, // Reference discovery is not atomic 1922 &_is_alive_closure_cm, // is alive closure 1923 true); // allow changes to number of processing threads 1924 1925 // STW ref processor 1926 _ref_processor_stw = 1927 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1928 mt_processing, // mt processing 1929 ParallelGCThreads, // degree of mt processing 1930 (ParallelGCThreads > 1), // mt discovery 1931 ParallelGCThreads, // degree of mt discovery 1932 true, // Reference discovery is atomic 1933 &_is_alive_closure_stw, // is alive closure 1934 true); // allow changes to number of processing threads 1935 } 1936 1937 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1938 return _collector_policy; 1939 } 1940 1941 G1CollectorPolicy* G1CollectedHeap::g1_collector_policy() const { 1942 return _collector_policy; 1943 } 1944 1945 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1946 return &_soft_ref_policy; 1947 } 1948 1949 size_t G1CollectedHeap::capacity() const { 1950 return _hrm->length() * HeapRegion::GrainBytes; 1951 } 1952 1953 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1954 return _hrm->total_free_bytes(); 1955 } 1956 1957 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1958 _hot_card_cache->drain(cl, worker_i); 1959 } 1960 1961 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1962 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1963 size_t n_completed_buffers = 0; 1964 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1965 n_completed_buffers++; 1966 } 1967 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!"); 1968 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1969 } 1970 1971 // Computes the sum of the storage used by the various regions. 1972 size_t G1CollectedHeap::used() const { 1973 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1974 if (_archive_allocator != NULL) { 1975 result += _archive_allocator->used(); 1976 } 1977 return result; 1978 } 1979 1980 size_t G1CollectedHeap::used_unlocked() const { 1981 return _summary_bytes_used; 1982 } 1983 1984 class SumUsedClosure: public HeapRegionClosure { 1985 size_t _used; 1986 public: 1987 SumUsedClosure() : _used(0) {} 1988 bool do_heap_region(HeapRegion* r) { 1989 _used += r->used(); 1990 return false; 1991 } 1992 size_t result() { return _used; } 1993 }; 1994 1995 size_t G1CollectedHeap::recalculate_used() const { 1996 SumUsedClosure blk; 1997 heap_region_iterate(&blk); 1998 return blk.result(); 1999 } 2000 2001 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2002 switch (cause) { 2003 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2004 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2005 case GCCause::_wb_conc_mark: return true; 2006 default : return false; 2007 } 2008 } 2009 2010 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2011 switch (cause) { 2012 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2013 case GCCause::_g1_humongous_allocation: return true; 2014 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2015 default: return is_user_requested_concurrent_full_gc(cause); 2016 } 2017 } 2018 2019 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2020 if(g1_policy()->force_upgrade_to_full()) { 2021 return true; 2022 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2023 return false; 2024 } else if (has_regions_left_for_allocation()) { 2025 return false; 2026 } else { 2027 return true; 2028 } 2029 } 2030 2031 #ifndef PRODUCT 2032 void G1CollectedHeap::allocate_dummy_regions() { 2033 // Let's fill up most of the region 2034 size_t word_size = HeapRegion::GrainWords - 1024; 2035 // And as a result the region we'll allocate will be humongous. 2036 guarantee(is_humongous(word_size), "sanity"); 2037 2038 // _filler_array_max_size is set to humongous object threshold 2039 // but temporarily change it to use CollectedHeap::fill_with_object(). 2040 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2041 2042 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2043 // Let's use the existing mechanism for the allocation 2044 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2045 if (dummy_obj != NULL) { 2046 MemRegion mr(dummy_obj, word_size); 2047 CollectedHeap::fill_with_object(mr); 2048 } else { 2049 // If we can't allocate once, we probably cannot allocate 2050 // again. Let's get out of the loop. 2051 break; 2052 } 2053 } 2054 } 2055 #endif // !PRODUCT 2056 2057 void G1CollectedHeap::increment_old_marking_cycles_started() { 2058 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2059 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2060 "Wrong marking cycle count (started: %d, completed: %d)", 2061 _old_marking_cycles_started, _old_marking_cycles_completed); 2062 2063 _old_marking_cycles_started++; 2064 } 2065 2066 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2067 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2068 2069 // We assume that if concurrent == true, then the caller is a 2070 // concurrent thread that was joined the Suspendible Thread 2071 // Set. If there's ever a cheap way to check this, we should add an 2072 // assert here. 2073 2074 // Given that this method is called at the end of a Full GC or of a 2075 // concurrent cycle, and those can be nested (i.e., a Full GC can 2076 // interrupt a concurrent cycle), the number of full collections 2077 // completed should be either one (in the case where there was no 2078 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2079 // behind the number of full collections started. 2080 2081 // This is the case for the inner caller, i.e. a Full GC. 2082 assert(concurrent || 2083 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2085 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2086 "is inconsistent with _old_marking_cycles_completed = %u", 2087 _old_marking_cycles_started, _old_marking_cycles_completed); 2088 2089 // This is the case for the outer caller, i.e. the concurrent cycle. 2090 assert(!concurrent || 2091 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2092 "for outer caller (concurrent cycle): " 2093 "_old_marking_cycles_started = %u " 2094 "is inconsistent with _old_marking_cycles_completed = %u", 2095 _old_marking_cycles_started, _old_marking_cycles_completed); 2096 2097 _old_marking_cycles_completed += 1; 2098 2099 // We need to clear the "in_progress" flag in the CM thread before 2100 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2101 // is set) so that if a waiter requests another System.gc() it doesn't 2102 // incorrectly see that a marking cycle is still in progress. 2103 if (concurrent) { 2104 _cm_thread->set_idle(); 2105 } 2106 2107 // This notify_all() will ensure that a thread that called 2108 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2109 // and it's waiting for a full GC to finish will be woken up. It is 2110 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2111 FullGCCount_lock->notify_all(); 2112 } 2113 2114 void G1CollectedHeap::collect(GCCause::Cause cause) { 2115 assert_heap_not_locked(); 2116 2117 uint gc_count_before; 2118 uint old_marking_count_before; 2119 uint full_gc_count_before; 2120 bool retry_gc; 2121 2122 do { 2123 retry_gc = false; 2124 2125 { 2126 MutexLocker ml(Heap_lock); 2127 2128 // Read the GC count while holding the Heap_lock 2129 gc_count_before = total_collections(); 2130 full_gc_count_before = total_full_collections(); 2131 old_marking_count_before = _old_marking_cycles_started; 2132 } 2133 2134 if (should_do_concurrent_full_gc(cause)) { 2135 // Schedule an initial-mark evacuation pause that will start a 2136 // concurrent cycle. We're setting word_size to 0 which means that 2137 // we are not requesting a post-GC allocation. 2138 VM_G1CollectForAllocation op(0, /* word_size */ 2139 gc_count_before, 2140 cause, 2141 true, /* should_initiate_conc_mark */ 2142 g1_policy()->max_pause_time_ms()); 2143 VMThread::execute(&op); 2144 if (!op.pause_succeeded()) { 2145 if (old_marking_count_before == _old_marking_cycles_started) { 2146 retry_gc = op.should_retry_gc(); 2147 } else { 2148 // A Full GC happened while we were trying to schedule the 2149 // initial-mark GC. No point in starting a new cycle given 2150 // that the whole heap was collected anyway. 2151 } 2152 2153 if (retry_gc) { 2154 if (GCLocker::is_active_and_needs_gc()) { 2155 GCLocker::stall_until_clear(); 2156 } 2157 } 2158 } 2159 } else { 2160 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2161 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2162 2163 // Schedule a standard evacuation pause. We're setting word_size 2164 // to 0 which means that we are not requesting a post-GC allocation. 2165 VM_G1CollectForAllocation op(0, /* word_size */ 2166 gc_count_before, 2167 cause, 2168 false, /* should_initiate_conc_mark */ 2169 g1_policy()->max_pause_time_ms()); 2170 VMThread::execute(&op); 2171 } else { 2172 // Schedule a Full GC. 2173 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2174 VMThread::execute(&op); 2175 } 2176 } 2177 } while (retry_gc); 2178 } 2179 2180 bool G1CollectedHeap::is_in(const void* p) const { 2181 if (_hrm->reserved().contains(p)) { 2182 // Given that we know that p is in the reserved space, 2183 // heap_region_containing() should successfully 2184 // return the containing region. 2185 HeapRegion* hr = heap_region_containing(p); 2186 return hr->is_in(p); 2187 } else { 2188 return false; 2189 } 2190 } 2191 2192 #ifdef ASSERT 2193 bool G1CollectedHeap::is_in_exact(const void* p) const { 2194 bool contains = reserved_region().contains(p); 2195 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2196 if (contains && available) { 2197 return true; 2198 } else { 2199 return false; 2200 } 2201 } 2202 #endif 2203 2204 // Iteration functions. 2205 2206 // Iterates an ObjectClosure over all objects within a HeapRegion. 2207 2208 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2209 ObjectClosure* _cl; 2210 public: 2211 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2212 bool do_heap_region(HeapRegion* r) { 2213 if (!r->is_continues_humongous()) { 2214 r->object_iterate(_cl); 2215 } 2216 return false; 2217 } 2218 }; 2219 2220 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2221 IterateObjectClosureRegionClosure blk(cl); 2222 heap_region_iterate(&blk); 2223 } 2224 2225 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2226 _hrm->iterate(cl); 2227 } 2228 2229 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2230 HeapRegionClaimer *hrclaimer, 2231 uint worker_id) const { 2232 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2233 } 2234 2235 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2236 HeapRegionClaimer *hrclaimer) const { 2237 _hrm->par_iterate(cl, hrclaimer, 0); 2238 } 2239 2240 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2241 _collection_set.iterate(cl); 2242 } 2243 2244 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2245 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2246 } 2247 2248 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2249 HeapRegion* hr = heap_region_containing(addr); 2250 return hr->block_start(addr); 2251 } 2252 2253 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2254 HeapRegion* hr = heap_region_containing(addr); 2255 return hr->block_size(addr); 2256 } 2257 2258 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2259 HeapRegion* hr = heap_region_containing(addr); 2260 return hr->block_is_obj(addr); 2261 } 2262 2263 bool G1CollectedHeap::supports_tlab_allocation() const { 2264 return true; 2265 } 2266 2267 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2268 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2269 } 2270 2271 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2272 return _eden.length() * HeapRegion::GrainBytes; 2273 } 2274 2275 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2276 // must be equal to the humongous object limit. 2277 size_t G1CollectedHeap::max_tlab_size() const { 2278 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2279 } 2280 2281 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2282 return _allocator->unsafe_max_tlab_alloc(); 2283 } 2284 2285 size_t G1CollectedHeap::max_capacity() const { 2286 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2287 } 2288 2289 size_t G1CollectedHeap::max_reserved_capacity() const { 2290 return _hrm->max_length() * HeapRegion::GrainBytes; 2291 } 2292 2293 jlong G1CollectedHeap::millis_since_last_gc() { 2294 // See the notes in GenCollectedHeap::millis_since_last_gc() 2295 // for more information about the implementation. 2296 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2297 _g1_policy->collection_pause_end_millis(); 2298 if (ret_val < 0) { 2299 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2300 ". returning zero instead.", ret_val); 2301 return 0; 2302 } 2303 return ret_val; 2304 } 2305 2306 void G1CollectedHeap::deduplicate_string(oop str) { 2307 assert(java_lang_String::is_instance(str), "invariant"); 2308 2309 if (G1StringDedup::is_enabled()) { 2310 G1StringDedup::deduplicate(str); 2311 } 2312 } 2313 2314 void G1CollectedHeap::prepare_for_verify() { 2315 _verifier->prepare_for_verify(); 2316 } 2317 2318 void G1CollectedHeap::verify(VerifyOption vo) { 2319 _verifier->verify(vo); 2320 } 2321 2322 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2323 return true; 2324 } 2325 2326 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2327 return _cm_thread->request_concurrent_phase(phase); 2328 } 2329 2330 class PrintRegionClosure: public HeapRegionClosure { 2331 outputStream* _st; 2332 public: 2333 PrintRegionClosure(outputStream* st) : _st(st) {} 2334 bool do_heap_region(HeapRegion* r) { 2335 r->print_on(_st); 2336 return false; 2337 } 2338 }; 2339 2340 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2341 const HeapRegion* hr, 2342 const VerifyOption vo) const { 2343 switch (vo) { 2344 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2345 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2346 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2347 default: ShouldNotReachHere(); 2348 } 2349 return false; // keep some compilers happy 2350 } 2351 2352 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2353 const VerifyOption vo) const { 2354 switch (vo) { 2355 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2356 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2357 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2358 default: ShouldNotReachHere(); 2359 } 2360 return false; // keep some compilers happy 2361 } 2362 2363 void G1CollectedHeap::print_heap_regions() const { 2364 LogTarget(Trace, gc, heap, region) lt; 2365 if (lt.is_enabled()) { 2366 LogStream ls(lt); 2367 print_regions_on(&ls); 2368 } 2369 } 2370 2371 void G1CollectedHeap::print_on(outputStream* st) const { 2372 st->print(" %-20s", "garbage-first heap"); 2373 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2374 capacity()/K, used_unlocked()/K); 2375 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2376 p2i(_hrm->reserved().start()), 2377 p2i(_hrm->reserved().end())); 2378 st->cr(); 2379 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2380 uint young_regions = young_regions_count(); 2381 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2382 (size_t) young_regions * HeapRegion::GrainBytes / K); 2383 uint survivor_regions = survivor_regions_count(); 2384 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2385 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2386 st->cr(); 2387 MetaspaceUtils::print_on(st); 2388 } 2389 2390 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2391 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2392 "HS=humongous(starts), HC=humongous(continues), " 2393 "CS=collection set, F=free, A=archive, " 2394 "TAMS=top-at-mark-start (previous, next)"); 2395 PrintRegionClosure blk(st); 2396 heap_region_iterate(&blk); 2397 } 2398 2399 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2400 print_on(st); 2401 2402 // Print the per-region information. 2403 print_regions_on(st); 2404 } 2405 2406 void G1CollectedHeap::print_on_error(outputStream* st) const { 2407 this->CollectedHeap::print_on_error(st); 2408 2409 if (_cm != NULL) { 2410 st->cr(); 2411 _cm->print_on_error(st); 2412 } 2413 } 2414 2415 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2416 workers()->print_worker_threads_on(st); 2417 _cm_thread->print_on(st); 2418 st->cr(); 2419 _cm->print_worker_threads_on(st); 2420 _cr->print_threads_on(st); 2421 _young_gen_sampling_thread->print_on(st); 2422 if (G1StringDedup::is_enabled()) { 2423 G1StringDedup::print_worker_threads_on(st); 2424 } 2425 } 2426 2427 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2428 workers()->threads_do(tc); 2429 tc->do_thread(_cm_thread); 2430 _cm->threads_do(tc); 2431 _cr->threads_do(tc); 2432 tc->do_thread(_young_gen_sampling_thread); 2433 if (G1StringDedup::is_enabled()) { 2434 G1StringDedup::threads_do(tc); 2435 } 2436 } 2437 2438 void G1CollectedHeap::print_tracing_info() const { 2439 g1_rem_set()->print_summary_info(); 2440 concurrent_mark()->print_summary_info(); 2441 } 2442 2443 #ifndef PRODUCT 2444 // Helpful for debugging RSet issues. 2445 2446 class PrintRSetsClosure : public HeapRegionClosure { 2447 private: 2448 const char* _msg; 2449 size_t _occupied_sum; 2450 2451 public: 2452 bool do_heap_region(HeapRegion* r) { 2453 HeapRegionRemSet* hrrs = r->rem_set(); 2454 size_t occupied = hrrs->occupied(); 2455 _occupied_sum += occupied; 2456 2457 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2458 if (occupied == 0) { 2459 tty->print_cr(" RSet is empty"); 2460 } else { 2461 hrrs->print(); 2462 } 2463 tty->print_cr("----------"); 2464 return false; 2465 } 2466 2467 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2468 tty->cr(); 2469 tty->print_cr("========================================"); 2470 tty->print_cr("%s", msg); 2471 tty->cr(); 2472 } 2473 2474 ~PrintRSetsClosure() { 2475 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2476 tty->print_cr("========================================"); 2477 tty->cr(); 2478 } 2479 }; 2480 2481 void G1CollectedHeap::print_cset_rsets() { 2482 PrintRSetsClosure cl("Printing CSet RSets"); 2483 collection_set_iterate(&cl); 2484 } 2485 2486 void G1CollectedHeap::print_all_rsets() { 2487 PrintRSetsClosure cl("Printing All RSets");; 2488 heap_region_iterate(&cl); 2489 } 2490 #endif // PRODUCT 2491 2492 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2493 2494 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2495 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2496 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2497 2498 size_t eden_capacity_bytes = 2499 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2500 2501 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2502 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2503 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2504 } 2505 2506 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2507 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2508 stats->unused(), stats->used(), stats->region_end_waste(), 2509 stats->regions_filled(), stats->direct_allocated(), 2510 stats->failure_used(), stats->failure_waste()); 2511 } 2512 2513 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2514 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2515 gc_tracer->report_gc_heap_summary(when, heap_summary); 2516 2517 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2518 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2519 } 2520 2521 G1CollectedHeap* G1CollectedHeap::heap() { 2522 CollectedHeap* heap = Universe::heap(); 2523 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2524 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2525 return (G1CollectedHeap*)heap; 2526 } 2527 2528 void G1CollectedHeap::gc_prologue(bool full) { 2529 // always_do_update_barrier = false; 2530 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2531 2532 // This summary needs to be printed before incrementing total collections. 2533 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2534 2535 // Update common counters. 2536 increment_total_collections(full /* full gc */); 2537 if (full) { 2538 increment_old_marking_cycles_started(); 2539 } 2540 2541 // Fill TLAB's and such 2542 double start = os::elapsedTime(); 2543 ensure_parsability(true); 2544 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2545 } 2546 2547 void G1CollectedHeap::gc_epilogue(bool full) { 2548 // Update common counters. 2549 if (full) { 2550 // Update the number of full collections that have been completed. 2551 increment_old_marking_cycles_completed(false /* concurrent */); 2552 } 2553 2554 // We are at the end of the GC. Total collections has already been increased. 2555 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2556 2557 // FIXME: what is this about? 2558 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2559 // is set. 2560 #if COMPILER2_OR_JVMCI 2561 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2562 #endif 2563 // always_do_update_barrier = true; 2564 2565 double start = os::elapsedTime(); 2566 resize_all_tlabs(); 2567 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2568 2569 MemoryService::track_memory_usage(); 2570 // We have just completed a GC. Update the soft reference 2571 // policy with the new heap occupancy 2572 Universe::update_heap_info_at_gc(); 2573 } 2574 2575 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2576 uint gc_count_before, 2577 bool* succeeded, 2578 GCCause::Cause gc_cause) { 2579 assert_heap_not_locked_and_not_at_safepoint(); 2580 VM_G1CollectForAllocation op(word_size, 2581 gc_count_before, 2582 gc_cause, 2583 false, /* should_initiate_conc_mark */ 2584 g1_policy()->max_pause_time_ms()); 2585 VMThread::execute(&op); 2586 2587 HeapWord* result = op.result(); 2588 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2589 assert(result == NULL || ret_succeeded, 2590 "the result should be NULL if the VM did not succeed"); 2591 *succeeded = ret_succeeded; 2592 2593 assert_heap_not_locked(); 2594 return result; 2595 } 2596 2597 void G1CollectedHeap::do_concurrent_mark() { 2598 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2599 if (!_cm_thread->in_progress()) { 2600 _cm_thread->set_started(); 2601 CGC_lock->notify(); 2602 } 2603 } 2604 2605 size_t G1CollectedHeap::pending_card_num() { 2606 struct CountCardsClosure : public ThreadClosure { 2607 size_t _cards; 2608 CountCardsClosure() : _cards(0) {} 2609 virtual void do_thread(Thread* t) { 2610 _cards += G1ThreadLocalData::dirty_card_queue(t).size(); 2611 } 2612 } count_from_threads; 2613 Threads::threads_do(&count_from_threads); 2614 2615 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2616 size_t buffer_size = dcqs.buffer_size(); 2617 size_t buffer_num = dcqs.completed_buffers_num(); 2618 2619 return buffer_size * buffer_num + count_from_threads._cards; 2620 } 2621 2622 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2623 // We don't nominate objects with many remembered set entries, on 2624 // the assumption that such objects are likely still live. 2625 HeapRegionRemSet* rem_set = r->rem_set(); 2626 2627 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2628 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2629 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2630 } 2631 2632 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2633 private: 2634 size_t _total_humongous; 2635 size_t _candidate_humongous; 2636 2637 G1DirtyCardQueue _dcq; 2638 2639 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2640 assert(region->is_starts_humongous(), "Must start a humongous object"); 2641 2642 oop obj = oop(region->bottom()); 2643 2644 // Dead objects cannot be eager reclaim candidates. Due to class 2645 // unloading it is unsafe to query their classes so we return early. 2646 if (g1h->is_obj_dead(obj, region)) { 2647 return false; 2648 } 2649 2650 // If we do not have a complete remembered set for the region, then we can 2651 // not be sure that we have all references to it. 2652 if (!region->rem_set()->is_complete()) { 2653 return false; 2654 } 2655 // Candidate selection must satisfy the following constraints 2656 // while concurrent marking is in progress: 2657 // 2658 // * In order to maintain SATB invariants, an object must not be 2659 // reclaimed if it was allocated before the start of marking and 2660 // has not had its references scanned. Such an object must have 2661 // its references (including type metadata) scanned to ensure no 2662 // live objects are missed by the marking process. Objects 2663 // allocated after the start of concurrent marking don't need to 2664 // be scanned. 2665 // 2666 // * An object must not be reclaimed if it is on the concurrent 2667 // mark stack. Objects allocated after the start of concurrent 2668 // marking are never pushed on the mark stack. 2669 // 2670 // Nominating only objects allocated after the start of concurrent 2671 // marking is sufficient to meet both constraints. This may miss 2672 // some objects that satisfy the constraints, but the marking data 2673 // structures don't support efficiently performing the needed 2674 // additional tests or scrubbing of the mark stack. 2675 // 2676 // However, we presently only nominate is_typeArray() objects. 2677 // A humongous object containing references induces remembered 2678 // set entries on other regions. In order to reclaim such an 2679 // object, those remembered sets would need to be cleaned up. 2680 // 2681 // We also treat is_typeArray() objects specially, allowing them 2682 // to be reclaimed even if allocated before the start of 2683 // concurrent mark. For this we rely on mark stack insertion to 2684 // exclude is_typeArray() objects, preventing reclaiming an object 2685 // that is in the mark stack. We also rely on the metadata for 2686 // such objects to be built-in and so ensured to be kept live. 2687 // Frequent allocation and drop of large binary blobs is an 2688 // important use case for eager reclaim, and this special handling 2689 // may reduce needed headroom. 2690 2691 return obj->is_typeArray() && 2692 g1h->is_potential_eager_reclaim_candidate(region); 2693 } 2694 2695 public: 2696 RegisterHumongousWithInCSetFastTestClosure() 2697 : _total_humongous(0), 2698 _candidate_humongous(0), 2699 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2700 } 2701 2702 virtual bool do_heap_region(HeapRegion* r) { 2703 if (!r->is_starts_humongous()) { 2704 return false; 2705 } 2706 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2707 2708 bool is_candidate = humongous_region_is_candidate(g1h, r); 2709 uint rindex = r->hrm_index(); 2710 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2711 if (is_candidate) { 2712 _candidate_humongous++; 2713 g1h->register_humongous_region_with_cset(rindex); 2714 // Is_candidate already filters out humongous object with large remembered sets. 2715 // If we have a humongous object with a few remembered sets, we simply flush these 2716 // remembered set entries into the DCQS. That will result in automatic 2717 // re-evaluation of their remembered set entries during the following evacuation 2718 // phase. 2719 if (!r->rem_set()->is_empty()) { 2720 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2721 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2722 G1CardTable* ct = g1h->card_table(); 2723 HeapRegionRemSetIterator hrrs(r->rem_set()); 2724 size_t card_index; 2725 while (hrrs.has_next(card_index)) { 2726 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2727 // The remembered set might contain references to already freed 2728 // regions. Filter out such entries to avoid failing card table 2729 // verification. 2730 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2731 if (*card_ptr != G1CardTable::dirty_card_val()) { 2732 *card_ptr = G1CardTable::dirty_card_val(); 2733 _dcq.enqueue(card_ptr); 2734 } 2735 } 2736 } 2737 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2738 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2739 hrrs.n_yielded(), r->rem_set()->occupied()); 2740 // We should only clear the card based remembered set here as we will not 2741 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2742 // (and probably never) we do not enter this path if there are other kind of 2743 // remembered sets for this region. 2744 r->rem_set()->clear_locked(true /* only_cardset */); 2745 // Clear_locked() above sets the state to Empty. However we want to continue 2746 // collecting remembered set entries for humongous regions that were not 2747 // reclaimed. 2748 r->rem_set()->set_state_complete(); 2749 } 2750 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2751 } 2752 _total_humongous++; 2753 2754 return false; 2755 } 2756 2757 size_t total_humongous() const { return _total_humongous; } 2758 size_t candidate_humongous() const { return _candidate_humongous; } 2759 2760 void flush_rem_set_entries() { _dcq.flush(); } 2761 }; 2762 2763 void G1CollectedHeap::register_humongous_regions_with_cset() { 2764 if (!G1EagerReclaimHumongousObjects) { 2765 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2766 return; 2767 } 2768 double time = os::elapsed_counter(); 2769 2770 // Collect reclaim candidate information and register candidates with cset. 2771 RegisterHumongousWithInCSetFastTestClosure cl; 2772 heap_region_iterate(&cl); 2773 2774 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2775 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2776 cl.total_humongous(), 2777 cl.candidate_humongous()); 2778 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2779 2780 // Finally flush all remembered set entries to re-check into the global DCQS. 2781 cl.flush_rem_set_entries(); 2782 } 2783 2784 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2785 public: 2786 bool do_heap_region(HeapRegion* hr) { 2787 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2788 hr->verify_rem_set(); 2789 } 2790 return false; 2791 } 2792 }; 2793 2794 uint G1CollectedHeap::num_task_queues() const { 2795 return _task_queues->size(); 2796 } 2797 2798 #if TASKQUEUE_STATS 2799 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2800 st->print_raw_cr("GC Task Stats"); 2801 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2802 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2803 } 2804 2805 void G1CollectedHeap::print_taskqueue_stats() const { 2806 if (!log_is_enabled(Trace, gc, task, stats)) { 2807 return; 2808 } 2809 Log(gc, task, stats) log; 2810 ResourceMark rm; 2811 LogStream ls(log.trace()); 2812 outputStream* st = &ls; 2813 2814 print_taskqueue_stats_hdr(st); 2815 2816 TaskQueueStats totals; 2817 const uint n = num_task_queues(); 2818 for (uint i = 0; i < n; ++i) { 2819 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2820 totals += task_queue(i)->stats; 2821 } 2822 st->print_raw("tot "); totals.print(st); st->cr(); 2823 2824 DEBUG_ONLY(totals.verify()); 2825 } 2826 2827 void G1CollectedHeap::reset_taskqueue_stats() { 2828 const uint n = num_task_queues(); 2829 for (uint i = 0; i < n; ++i) { 2830 task_queue(i)->stats.reset(); 2831 } 2832 } 2833 #endif // TASKQUEUE_STATS 2834 2835 void G1CollectedHeap::wait_for_root_region_scanning() { 2836 double scan_wait_start = os::elapsedTime(); 2837 // We have to wait until the CM threads finish scanning the 2838 // root regions as it's the only way to ensure that all the 2839 // objects on them have been correctly scanned before we start 2840 // moving them during the GC. 2841 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2842 double wait_time_ms = 0.0; 2843 if (waited) { 2844 double scan_wait_end = os::elapsedTime(); 2845 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2846 } 2847 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2848 } 2849 2850 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2851 private: 2852 G1HRPrinter* _hr_printer; 2853 public: 2854 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2855 2856 virtual bool do_heap_region(HeapRegion* r) { 2857 _hr_printer->cset(r); 2858 return false; 2859 } 2860 }; 2861 2862 void G1CollectedHeap::start_new_collection_set() { 2863 collection_set()->start_incremental_building(); 2864 2865 clear_cset_fast_test(); 2866 2867 guarantee(_eden.length() == 0, "eden should have been cleared"); 2868 g1_policy()->transfer_survivors_to_cset(survivor()); 2869 } 2870 2871 bool 2872 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2873 assert_at_safepoint_on_vm_thread(); 2874 guarantee(!is_gc_active(), "collection is not reentrant"); 2875 2876 if (GCLocker::check_active_before_gc()) { 2877 return false; 2878 } 2879 2880 _gc_timer_stw->register_gc_start(); 2881 2882 GCIdMark gc_id_mark; 2883 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2884 2885 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2886 ResourceMark rm; 2887 2888 g1_policy()->note_gc_start(); 2889 2890 wait_for_root_region_scanning(); 2891 2892 print_heap_before_gc(); 2893 print_heap_regions(); 2894 trace_heap_before_gc(_gc_tracer_stw); 2895 2896 _verifier->verify_region_sets_optional(); 2897 _verifier->verify_dirty_young_regions(); 2898 2899 // We should not be doing initial mark unless the conc mark thread is running 2900 if (!_cm_thread->should_terminate()) { 2901 // This call will decide whether this pause is an initial-mark 2902 // pause. If it is, in_initial_mark_gc() will return true 2903 // for the duration of this pause. 2904 g1_policy()->decide_on_conc_mark_initiation(); 2905 } 2906 2907 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2908 assert(!collector_state()->in_initial_mark_gc() || 2909 collector_state()->in_young_only_phase(), "sanity"); 2910 2911 // We also do not allow mixed GCs during marking. 2912 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2913 2914 // Record whether this pause is an initial mark. When the current 2915 // thread has completed its logging output and it's safe to signal 2916 // the CM thread, the flag's value in the policy has been reset. 2917 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2918 2919 // Inner scope for scope based logging, timers, and stats collection 2920 { 2921 G1EvacuationInfo evacuation_info; 2922 2923 if (collector_state()->in_initial_mark_gc()) { 2924 // We are about to start a marking cycle, so we increment the 2925 // full collection counter. 2926 increment_old_marking_cycles_started(); 2927 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2928 } 2929 2930 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2931 2932 GCTraceCPUTime tcpu; 2933 2934 G1HeapVerifier::G1VerifyType verify_type; 2935 FormatBuffer<> gc_string("Pause Young "); 2936 if (collector_state()->in_initial_mark_gc()) { 2937 gc_string.append("(Concurrent Start)"); 2938 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2939 } else if (collector_state()->in_young_only_phase()) { 2940 if (collector_state()->in_young_gc_before_mixed()) { 2941 gc_string.append("(Prepare Mixed)"); 2942 } else { 2943 gc_string.append("(Normal)"); 2944 } 2945 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2946 } else { 2947 gc_string.append("(Mixed)"); 2948 verify_type = G1HeapVerifier::G1VerifyMixed; 2949 } 2950 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2951 2952 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2953 workers()->active_workers(), 2954 Threads::number_of_non_daemon_threads()); 2955 active_workers = workers()->update_active_workers(active_workers); 2956 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2957 2958 G1MonitoringScope ms(g1mm(), 2959 false /* full_gc */, 2960 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2961 2962 G1HeapTransition heap_transition(this); 2963 size_t heap_used_bytes_before_gc = used(); 2964 2965 // Don't dynamically change the number of GC threads this early. A value of 2966 // 0 is used to indicate serial work. When parallel work is done, 2967 // it will be set. 2968 2969 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2970 IsGCActiveMark x; 2971 2972 gc_prologue(false); 2973 2974 if (VerifyRememberedSets) { 2975 log_info(gc, verify)("[Verifying RemSets before GC]"); 2976 VerifyRegionRemSetClosure v_cl; 2977 heap_region_iterate(&v_cl); 2978 } 2979 2980 _verifier->verify_before_gc(verify_type); 2981 2982 _verifier->check_bitmaps("GC Start"); 2983 2984 #if COMPILER2_OR_JVMCI 2985 DerivedPointerTable::clear(); 2986 #endif 2987 2988 // Please see comment in g1CollectedHeap.hpp and 2989 // G1CollectedHeap::ref_processing_init() to see how 2990 // reference processing currently works in G1. 2991 2992 // Enable discovery in the STW reference processor 2993 _ref_processor_stw->enable_discovery(); 2994 2995 { 2996 // We want to temporarily turn off discovery by the 2997 // CM ref processor, if necessary, and turn it back on 2998 // on again later if we do. Using a scoped 2999 // NoRefDiscovery object will do this. 3000 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 3001 3002 // Forget the current alloc region (we might even choose it to be part 3003 // of the collection set!). 3004 _allocator->release_mutator_alloc_region(); 3005 3006 // This timing is only used by the ergonomics to handle our pause target. 3007 // It is unclear why this should not include the full pause. We will 3008 // investigate this in CR 7178365. 3009 // 3010 // Preserving the old comment here if that helps the investigation: 3011 // 3012 // The elapsed time induced by the start time below deliberately elides 3013 // the possible verification above. 3014 double sample_start_time_sec = os::elapsedTime(); 3015 3016 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3017 3018 if (collector_state()->in_initial_mark_gc()) { 3019 concurrent_mark()->pre_initial_mark(); 3020 } 3021 3022 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 3023 3024 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3025 3026 register_humongous_regions_with_cset(); 3027 3028 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3029 3030 // We call this after finalize_cset() to 3031 // ensure that the CSet has been finalized. 3032 _cm->verify_no_cset_oops(); 3033 3034 if (_hr_printer.is_active()) { 3035 G1PrintCollectionSetClosure cl(&_hr_printer); 3036 _collection_set.iterate(&cl); 3037 } 3038 3039 // Initialize the GC alloc regions. 3040 _allocator->init_gc_alloc_regions(evacuation_info); 3041 3042 G1ParScanThreadStateSet per_thread_states(this, 3043 workers()->active_workers(), 3044 collection_set()->young_region_length(), 3045 collection_set()->optional_region_length()); 3046 pre_evacuate_collection_set(); 3047 3048 // Actually do the work... 3049 evacuate_collection_set(&per_thread_states); 3050 evacuate_optional_collection_set(&per_thread_states); 3051 3052 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3053 3054 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3055 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3056 3057 eagerly_reclaim_humongous_regions(); 3058 3059 record_obj_copy_mem_stats(); 3060 _survivor_evac_stats.adjust_desired_plab_sz(); 3061 _old_evac_stats.adjust_desired_plab_sz(); 3062 3063 double start = os::elapsedTime(); 3064 start_new_collection_set(); 3065 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3066 3067 if (evacuation_failed()) { 3068 double recalculate_used_start = os::elapsedTime(); 3069 set_used(recalculate_used()); 3070 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3071 3072 if (_archive_allocator != NULL) { 3073 _archive_allocator->clear_used(); 3074 } 3075 for (uint i = 0; i < ParallelGCThreads; i++) { 3076 if (_evacuation_failed_info_array[i].has_failed()) { 3077 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3078 } 3079 } 3080 } else { 3081 // The "used" of the the collection set have already been subtracted 3082 // when they were freed. Add in the bytes evacuated. 3083 increase_used(g1_policy()->bytes_copied_during_gc()); 3084 } 3085 3086 if (collector_state()->in_initial_mark_gc()) { 3087 // We have to do this before we notify the CM threads that 3088 // they can start working to make sure that all the 3089 // appropriate initialization is done on the CM object. 3090 concurrent_mark()->post_initial_mark(); 3091 // Note that we don't actually trigger the CM thread at 3092 // this point. We do that later when we're sure that 3093 // the current thread has completed its logging output. 3094 } 3095 3096 allocate_dummy_regions(); 3097 3098 _allocator->init_mutator_alloc_region(); 3099 3100 { 3101 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3102 if (expand_bytes > 0) { 3103 size_t bytes_before = capacity(); 3104 // No need for an ergo logging here, 3105 // expansion_amount() does this when it returns a value > 0. 3106 double expand_ms; 3107 if (!expand(expand_bytes, _workers, &expand_ms)) { 3108 // We failed to expand the heap. Cannot do anything about it. 3109 } 3110 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3111 } 3112 } 3113 3114 // We redo the verification but now wrt to the new CSet which 3115 // has just got initialized after the previous CSet was freed. 3116 _cm->verify_no_cset_oops(); 3117 3118 // This timing is only used by the ergonomics to handle our pause target. 3119 // It is unclear why this should not include the full pause. We will 3120 // investigate this in CR 7178365. 3121 double sample_end_time_sec = os::elapsedTime(); 3122 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3123 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3124 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3125 3126 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3127 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3128 3129 if (VerifyRememberedSets) { 3130 log_info(gc, verify)("[Verifying RemSets after GC]"); 3131 VerifyRegionRemSetClosure v_cl; 3132 heap_region_iterate(&v_cl); 3133 } 3134 3135 _verifier->verify_after_gc(verify_type); 3136 _verifier->check_bitmaps("GC End"); 3137 3138 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3139 _ref_processor_stw->verify_no_references_recorded(); 3140 3141 // CM reference discovery will be re-enabled if necessary. 3142 } 3143 3144 #ifdef TRACESPINNING 3145 ParallelTaskTerminator::print_termination_counts(); 3146 #endif 3147 3148 gc_epilogue(false); 3149 } 3150 3151 // Print the remainder of the GC log output. 3152 if (evacuation_failed()) { 3153 log_info(gc)("To-space exhausted"); 3154 } 3155 3156 g1_policy()->print_phases(); 3157 heap_transition.print(); 3158 3159 // It is not yet to safe to tell the concurrent mark to 3160 // start as we have some optional output below. We don't want the 3161 // output from the concurrent mark thread interfering with this 3162 // logging output either. 3163 3164 _hrm->verify_optional(); 3165 _verifier->verify_region_sets_optional(); 3166 3167 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3168 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3169 3170 print_heap_after_gc(); 3171 print_heap_regions(); 3172 trace_heap_after_gc(_gc_tracer_stw); 3173 3174 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3175 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3176 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3177 // before any GC notifications are raised. 3178 g1mm()->update_sizes(); 3179 3180 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3181 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3182 _gc_timer_stw->register_gc_end(); 3183 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3184 } 3185 // It should now be safe to tell the concurrent mark thread to start 3186 // without its logging output interfering with the logging output 3187 // that came from the pause. 3188 3189 if (should_start_conc_mark) { 3190 // CAUTION: after the doConcurrentMark() call below, 3191 // the concurrent marking thread(s) could be running 3192 // concurrently with us. Make sure that anything after 3193 // this point does not assume that we are the only GC thread 3194 // running. Note: of course, the actual marking work will 3195 // not start until the safepoint itself is released in 3196 // SuspendibleThreadSet::desynchronize(). 3197 do_concurrent_mark(); 3198 } 3199 3200 return true; 3201 } 3202 3203 void G1CollectedHeap::remove_self_forwarding_pointers() { 3204 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3205 workers()->run_task(&rsfp_task); 3206 } 3207 3208 void G1CollectedHeap::restore_after_evac_failure() { 3209 double remove_self_forwards_start = os::elapsedTime(); 3210 3211 remove_self_forwarding_pointers(); 3212 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3213 _preserved_marks_set.restore(&task_executor); 3214 3215 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3216 } 3217 3218 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3219 if (!_evacuation_failed) { 3220 _evacuation_failed = true; 3221 } 3222 3223 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3224 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3225 } 3226 3227 bool G1ParEvacuateFollowersClosure::offer_termination() { 3228 EventGCPhaseParallel event; 3229 G1ParScanThreadState* const pss = par_scan_state(); 3230 start_term_time(); 3231 const bool res = terminator()->offer_termination(); 3232 end_term_time(); 3233 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3234 return res; 3235 } 3236 3237 void G1ParEvacuateFollowersClosure::do_void() { 3238 EventGCPhaseParallel event; 3239 G1ParScanThreadState* const pss = par_scan_state(); 3240 pss->trim_queue(); 3241 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3242 do { 3243 EventGCPhaseParallel event; 3244 pss->steal_and_trim_queue(queues()); 3245 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3246 } while (!offer_termination()); 3247 } 3248 3249 class G1ParTask : public AbstractGangTask { 3250 protected: 3251 G1CollectedHeap* _g1h; 3252 G1ParScanThreadStateSet* _pss; 3253 RefToScanQueueSet* _queues; 3254 G1RootProcessor* _root_processor; 3255 TaskTerminator _terminator; 3256 uint _n_workers; 3257 3258 public: 3259 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3260 : AbstractGangTask("G1 collection"), 3261 _g1h(g1h), 3262 _pss(per_thread_states), 3263 _queues(task_queues), 3264 _root_processor(root_processor), 3265 _terminator(n_workers, _queues), 3266 _n_workers(n_workers) 3267 {} 3268 3269 void work(uint worker_id) { 3270 if (worker_id >= _n_workers) return; // no work needed this round 3271 3272 double start_sec = os::elapsedTime(); 3273 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3274 3275 { 3276 ResourceMark rm; 3277 HandleMark hm; 3278 3279 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3280 3281 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3282 pss->set_ref_discoverer(rp); 3283 3284 double start_strong_roots_sec = os::elapsedTime(); 3285 3286 _root_processor->evacuate_roots(pss, worker_id); 3287 3288 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3289 3290 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3291 3292 double term_sec = 0.0; 3293 size_t evac_term_attempts = 0; 3294 { 3295 double start = os::elapsedTime(); 3296 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy); 3297 evac.do_void(); 3298 3299 evac_term_attempts = evac.term_attempts(); 3300 term_sec = evac.term_time(); 3301 double elapsed_sec = os::elapsedTime() - start; 3302 3303 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3304 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3305 3306 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy, 3307 worker_id, 3308 pss->lab_waste_words() * HeapWordSize, 3309 G1GCPhaseTimes::ObjCopyLABWaste); 3310 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy, 3311 worker_id, 3312 pss->lab_undo_waste_words() * HeapWordSize, 3313 G1GCPhaseTimes::ObjCopyLABUndoWaste); 3314 3315 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3316 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3317 } 3318 3319 assert(pss->queue_is_empty(), "should be empty"); 3320 3321 // Close the inner scope so that the ResourceMark and HandleMark 3322 // destructors are executed here and are included as part of the 3323 // "GC Worker Time". 3324 } 3325 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3326 } 3327 }; 3328 3329 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3330 bool class_unloading_occurred) { 3331 uint num_workers = workers()->active_workers(); 3332 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3333 workers()->run_task(&unlink_task); 3334 } 3335 3336 // Clean string dedup data structures. 3337 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3338 // record the durations of the phases. Hence the almost-copy. 3339 class G1StringDedupCleaningTask : public AbstractGangTask { 3340 BoolObjectClosure* _is_alive; 3341 OopClosure* _keep_alive; 3342 G1GCPhaseTimes* _phase_times; 3343 3344 public: 3345 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3346 OopClosure* keep_alive, 3347 G1GCPhaseTimes* phase_times) : 3348 AbstractGangTask("Partial Cleaning Task"), 3349 _is_alive(is_alive), 3350 _keep_alive(keep_alive), 3351 _phase_times(phase_times) 3352 { 3353 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3354 StringDedup::gc_prologue(true); 3355 } 3356 3357 ~G1StringDedupCleaningTask() { 3358 StringDedup::gc_epilogue(); 3359 } 3360 3361 void work(uint worker_id) { 3362 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3363 { 3364 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3365 StringDedupQueue::unlink_or_oops_do(&cl); 3366 } 3367 { 3368 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3369 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3370 } 3371 } 3372 }; 3373 3374 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3375 OopClosure* keep_alive, 3376 G1GCPhaseTimes* phase_times) { 3377 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3378 workers()->run_task(&cl); 3379 } 3380 3381 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3382 private: 3383 G1DirtyCardQueueSet* _queue; 3384 G1CollectedHeap* _g1h; 3385 public: 3386 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3387 _queue(queue), _g1h(g1h) { } 3388 3389 virtual void work(uint worker_id) { 3390 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3391 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3392 3393 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3394 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3395 3396 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3397 } 3398 }; 3399 3400 void G1CollectedHeap::redirty_logged_cards() { 3401 double redirty_logged_cards_start = os::elapsedTime(); 3402 3403 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3404 dirty_card_queue_set().reset_for_par_iteration(); 3405 workers()->run_task(&redirty_task); 3406 3407 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3408 dcq.merge_bufferlists(&dirty_card_queue_set()); 3409 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3410 3411 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3412 } 3413 3414 // Weak Reference Processing support 3415 3416 bool G1STWIsAliveClosure::do_object_b(oop p) { 3417 // An object is reachable if it is outside the collection set, 3418 // or is inside and copied. 3419 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3420 } 3421 3422 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3423 assert(obj != NULL, "must not be NULL"); 3424 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3425 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3426 // may falsely indicate that this is not the case here: however the collection set only 3427 // contains old regions when concurrent mark is not running. 3428 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3429 } 3430 3431 // Non Copying Keep Alive closure 3432 class G1KeepAliveClosure: public OopClosure { 3433 G1CollectedHeap*_g1h; 3434 public: 3435 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3436 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3437 void do_oop(oop* p) { 3438 oop obj = *p; 3439 assert(obj != NULL, "the caller should have filtered out NULL values"); 3440 3441 const InCSetState cset_state =_g1h->in_cset_state(obj); 3442 if (!cset_state.is_in_cset_or_humongous()) { 3443 return; 3444 } 3445 if (cset_state.is_in_cset()) { 3446 assert( obj->is_forwarded(), "invariant" ); 3447 *p = obj->forwardee(); 3448 } else { 3449 assert(!obj->is_forwarded(), "invariant" ); 3450 assert(cset_state.is_humongous(), 3451 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3452 _g1h->set_humongous_is_live(obj); 3453 } 3454 } 3455 }; 3456 3457 // Copying Keep Alive closure - can be called from both 3458 // serial and parallel code as long as different worker 3459 // threads utilize different G1ParScanThreadState instances 3460 // and different queues. 3461 3462 class G1CopyingKeepAliveClosure: public OopClosure { 3463 G1CollectedHeap* _g1h; 3464 G1ParScanThreadState* _par_scan_state; 3465 3466 public: 3467 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3468 G1ParScanThreadState* pss): 3469 _g1h(g1h), 3470 _par_scan_state(pss) 3471 {} 3472 3473 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3474 virtual void do_oop( oop* p) { do_oop_work(p); } 3475 3476 template <class T> void do_oop_work(T* p) { 3477 oop obj = RawAccess<>::oop_load(p); 3478 3479 if (_g1h->is_in_cset_or_humongous(obj)) { 3480 // If the referent object has been forwarded (either copied 3481 // to a new location or to itself in the event of an 3482 // evacuation failure) then we need to update the reference 3483 // field and, if both reference and referent are in the G1 3484 // heap, update the RSet for the referent. 3485 // 3486 // If the referent has not been forwarded then we have to keep 3487 // it alive by policy. Therefore we have copy the referent. 3488 // 3489 // When the queue is drained (after each phase of reference processing) 3490 // the object and it's followers will be copied, the reference field set 3491 // to point to the new location, and the RSet updated. 3492 _par_scan_state->push_on_queue(p); 3493 } 3494 } 3495 }; 3496 3497 // Serial drain queue closure. Called as the 'complete_gc' 3498 // closure for each discovered list in some of the 3499 // reference processing phases. 3500 3501 class G1STWDrainQueueClosure: public VoidClosure { 3502 protected: 3503 G1CollectedHeap* _g1h; 3504 G1ParScanThreadState* _par_scan_state; 3505 3506 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3507 3508 public: 3509 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3510 _g1h(g1h), 3511 _par_scan_state(pss) 3512 { } 3513 3514 void do_void() { 3515 G1ParScanThreadState* const pss = par_scan_state(); 3516 pss->trim_queue(); 3517 } 3518 }; 3519 3520 // Parallel Reference Processing closures 3521 3522 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3523 // processing during G1 evacuation pauses. 3524 3525 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3526 private: 3527 G1CollectedHeap* _g1h; 3528 G1ParScanThreadStateSet* _pss; 3529 RefToScanQueueSet* _queues; 3530 WorkGang* _workers; 3531 3532 public: 3533 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3534 G1ParScanThreadStateSet* per_thread_states, 3535 WorkGang* workers, 3536 RefToScanQueueSet *task_queues) : 3537 _g1h(g1h), 3538 _pss(per_thread_states), 3539 _queues(task_queues), 3540 _workers(workers) 3541 { 3542 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3543 } 3544 3545 // Executes the given task using concurrent marking worker threads. 3546 virtual void execute(ProcessTask& task, uint ergo_workers); 3547 }; 3548 3549 // Gang task for possibly parallel reference processing 3550 3551 class G1STWRefProcTaskProxy: public AbstractGangTask { 3552 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3553 ProcessTask& _proc_task; 3554 G1CollectedHeap* _g1h; 3555 G1ParScanThreadStateSet* _pss; 3556 RefToScanQueueSet* _task_queues; 3557 ParallelTaskTerminator* _terminator; 3558 3559 public: 3560 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3561 G1CollectedHeap* g1h, 3562 G1ParScanThreadStateSet* per_thread_states, 3563 RefToScanQueueSet *task_queues, 3564 ParallelTaskTerminator* terminator) : 3565 AbstractGangTask("Process reference objects in parallel"), 3566 _proc_task(proc_task), 3567 _g1h(g1h), 3568 _pss(per_thread_states), 3569 _task_queues(task_queues), 3570 _terminator(terminator) 3571 {} 3572 3573 virtual void work(uint worker_id) { 3574 // The reference processing task executed by a single worker. 3575 ResourceMark rm; 3576 HandleMark hm; 3577 3578 G1STWIsAliveClosure is_alive(_g1h); 3579 3580 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3581 pss->set_ref_discoverer(NULL); 3582 3583 // Keep alive closure. 3584 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3585 3586 // Complete GC closure 3587 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3588 3589 // Call the reference processing task's work routine. 3590 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3591 3592 // Note we cannot assert that the refs array is empty here as not all 3593 // of the processing tasks (specifically phase2 - pp2_work) execute 3594 // the complete_gc closure (which ordinarily would drain the queue) so 3595 // the queue may not be empty. 3596 } 3597 }; 3598 3599 // Driver routine for parallel reference processing. 3600 // Creates an instance of the ref processing gang 3601 // task and has the worker threads execute it. 3602 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3603 assert(_workers != NULL, "Need parallel worker threads."); 3604 3605 assert(_workers->active_workers() >= ergo_workers, 3606 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3607 ergo_workers, _workers->active_workers()); 3608 TaskTerminator terminator(ergo_workers, _queues); 3609 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3610 3611 _workers->run_task(&proc_task_proxy, ergo_workers); 3612 } 3613 3614 // End of weak reference support closures 3615 3616 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3617 double ref_proc_start = os::elapsedTime(); 3618 3619 ReferenceProcessor* rp = _ref_processor_stw; 3620 assert(rp->discovery_enabled(), "should have been enabled"); 3621 3622 // Closure to test whether a referent is alive. 3623 G1STWIsAliveClosure is_alive(this); 3624 3625 // Even when parallel reference processing is enabled, the processing 3626 // of JNI refs is serial and performed serially by the current thread 3627 // rather than by a worker. The following PSS will be used for processing 3628 // JNI refs. 3629 3630 // Use only a single queue for this PSS. 3631 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3632 pss->set_ref_discoverer(NULL); 3633 assert(pss->queue_is_empty(), "pre-condition"); 3634 3635 // Keep alive closure. 3636 G1CopyingKeepAliveClosure keep_alive(this, pss); 3637 3638 // Serial Complete GC closure 3639 G1STWDrainQueueClosure drain_queue(this, pss); 3640 3641 // Setup the soft refs policy... 3642 rp->setup_policy(false); 3643 3644 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3645 3646 ReferenceProcessorStats stats; 3647 if (!rp->processing_is_mt()) { 3648 // Serial reference processing... 3649 stats = rp->process_discovered_references(&is_alive, 3650 &keep_alive, 3651 &drain_queue, 3652 NULL, 3653 pt); 3654 } else { 3655 uint no_of_gc_workers = workers()->active_workers(); 3656 3657 // Parallel reference processing 3658 assert(no_of_gc_workers <= rp->max_num_queues(), 3659 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3660 no_of_gc_workers, rp->max_num_queues()); 3661 3662 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3663 stats = rp->process_discovered_references(&is_alive, 3664 &keep_alive, 3665 &drain_queue, 3666 &par_task_executor, 3667 pt); 3668 } 3669 3670 _gc_tracer_stw->report_gc_reference_stats(stats); 3671 3672 // We have completed copying any necessary live referent objects. 3673 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3674 3675 make_pending_list_reachable(); 3676 3677 rp->verify_no_references_recorded(); 3678 3679 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3680 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3681 } 3682 3683 void G1CollectedHeap::make_pending_list_reachable() { 3684 if (collector_state()->in_initial_mark_gc()) { 3685 oop pll_head = Universe::reference_pending_list(); 3686 if (pll_head != NULL) { 3687 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3688 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3689 } 3690 } 3691 } 3692 3693 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3694 double merge_pss_time_start = os::elapsedTime(); 3695 per_thread_states->flush(); 3696 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3697 } 3698 3699 void G1CollectedHeap::pre_evacuate_collection_set() { 3700 _expand_heap_after_alloc_failure = true; 3701 _evacuation_failed = false; 3702 3703 // Disable the hot card cache. 3704 _hot_card_cache->reset_hot_cache_claimed_index(); 3705 _hot_card_cache->set_use_cache(false); 3706 3707 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3708 _preserved_marks_set.assert_empty(); 3709 3710 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3711 3712 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3713 if (collector_state()->in_initial_mark_gc()) { 3714 double start_clear_claimed_marks = os::elapsedTime(); 3715 3716 ClassLoaderDataGraph::clear_claimed_marks(); 3717 3718 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3719 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3720 } 3721 } 3722 3723 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3724 // Should G1EvacuationFailureALot be in effect for this GC? 3725 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3726 3727 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3728 3729 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3730 3731 double start_par_time_sec = os::elapsedTime(); 3732 double end_par_time_sec; 3733 3734 { 3735 const uint n_workers = workers()->active_workers(); 3736 G1RootProcessor root_processor(this, n_workers); 3737 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3738 3739 workers()->run_task(&g1_par_task); 3740 end_par_time_sec = os::elapsedTime(); 3741 3742 // Closing the inner scope will execute the destructor 3743 // for the G1RootProcessor object. We record the current 3744 // elapsed time before closing the scope so that time 3745 // taken for the destructor is NOT included in the 3746 // reported parallel time. 3747 } 3748 3749 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3750 phase_times->record_par_time(par_time_ms); 3751 3752 double code_root_fixup_time_ms = 3753 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3754 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 3755 } 3756 3757 class G1EvacuateOptionalRegionTask : public AbstractGangTask { 3758 G1CollectedHeap* _g1h; 3759 G1ParScanThreadStateSet* _per_thread_states; 3760 G1OptionalCSet* _optional; 3761 RefToScanQueueSet* _queues; 3762 ParallelTaskTerminator _terminator; 3763 3764 Tickspan trim_ticks(G1ParScanThreadState* pss) { 3765 Tickspan copy_time = pss->trim_ticks(); 3766 pss->reset_trim_ticks(); 3767 return copy_time; 3768 } 3769 3770 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3771 G1EvacuationRootClosures* root_cls = pss->closures(); 3772 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss); 3773 3774 size_t scanned = 0; 3775 size_t claimed = 0; 3776 size_t skipped = 0; 3777 size_t used_memory = 0; 3778 3779 Ticks start = Ticks::now(); 3780 Tickspan copy_time; 3781 3782 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) { 3783 HeapRegion* hr = _optional->region_at(i); 3784 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl); 3785 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops()); 3786 copy_time += trim_ticks(pss); 3787 3788 G1ScanRSForRegionClosure scan_rs_cl(_g1h->g1_rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id); 3789 scan_rs_cl.do_heap_region(hr); 3790 copy_time += trim_ticks(pss); 3791 scanned += scan_rs_cl.cards_scanned(); 3792 claimed += scan_rs_cl.cards_claimed(); 3793 skipped += scan_rs_cl.cards_skipped(); 3794 3795 // Chunk lists for this region is no longer needed. 3796 used_memory += pss->oops_into_optional_region(hr)->used_memory(); 3797 } 3798 3799 Tickspan scan_time = (Ticks::now() - start) - copy_time; 3800 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3801 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds()); 3802 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds()); 3803 3804 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards); 3805 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards); 3806 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards); 3807 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory); 3808 } 3809 3810 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3811 Ticks start = Ticks::now(); 3812 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy); 3813 cl.do_void(); 3814 3815 Tickspan evac_time = (Ticks::now() - start); 3816 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3817 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds()); 3818 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation"); 3819 } 3820 3821 public: 3822 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h, 3823 G1ParScanThreadStateSet* per_thread_states, 3824 G1OptionalCSet* cset, 3825 RefToScanQueueSet* queues, 3826 uint n_workers) : 3827 AbstractGangTask("G1 Evacuation Optional Region Task"), 3828 _g1h(g1h), 3829 _per_thread_states(per_thread_states), 3830 _optional(cset), 3831 _queues(queues), 3832 _terminator(n_workers, _queues) { 3833 } 3834 3835 void work(uint worker_id) { 3836 ResourceMark rm; 3837 HandleMark hm; 3838 3839 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3840 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3841 3842 scan_roots(pss, worker_id); 3843 evacuate_live_objects(pss, worker_id); 3844 } 3845 }; 3846 3847 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) { 3848 class G1MarkScope : public MarkScope {}; 3849 G1MarkScope code_mark_scope; 3850 3851 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers()); 3852 workers()->run_task(&task); 3853 } 3854 3855 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3856 G1OptionalCSet optional_cset(&_collection_set, per_thread_states); 3857 if (optional_cset.is_empty()) { 3858 return; 3859 } 3860 3861 if (evacuation_failed()) { 3862 return; 3863 } 3864 3865 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3866 const double gc_start_time_ms = phase_times->cur_collection_start_sec() * 1000.0; 3867 3868 double start_time_sec = os::elapsedTime(); 3869 3870 do { 3871 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3872 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3873 3874 if (time_left_ms < 0) { 3875 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms); 3876 break; 3877 } 3878 3879 optional_cset.prepare_evacuation(time_left_ms * _g1_policy->optional_evacuation_fraction()); 3880 if (optional_cset.prepare_failed()) { 3881 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms); 3882 break; 3883 } 3884 3885 evacuate_optional_regions(per_thread_states, &optional_cset); 3886 3887 optional_cset.complete_evacuation(); 3888 if (optional_cset.evacuation_failed()) { 3889 break; 3890 } 3891 } while (!optional_cset.is_empty()); 3892 3893 phase_times->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0); 3894 } 3895 3896 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3897 // Also cleans the card table from temporary duplicate detection information used 3898 // during UpdateRS/ScanRS. 3899 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 3900 3901 // Process any discovered reference objects - we have 3902 // to do this _before_ we retire the GC alloc regions 3903 // as we may have to copy some 'reachable' referent 3904 // objects (and their reachable sub-graphs) that were 3905 // not copied during the pause. 3906 process_discovered_references(per_thread_states); 3907 3908 G1STWIsAliveClosure is_alive(this); 3909 G1KeepAliveClosure keep_alive(this); 3910 3911 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3912 g1_policy()->phase_times()->weak_phase_times()); 3913 3914 if (G1StringDedup::is_enabled()) { 3915 double string_dedup_time_ms = os::elapsedTime(); 3916 3917 string_dedup_cleaning(&is_alive, &keep_alive, g1_policy()->phase_times()); 3918 3919 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3920 g1_policy()->phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3921 } 3922 3923 if (evacuation_failed()) { 3924 restore_after_evac_failure(); 3925 3926 // Reset the G1EvacuationFailureALot counters and flags 3927 // Note: the values are reset only when an actual 3928 // evacuation failure occurs. 3929 NOT_PRODUCT(reset_evacuation_should_fail();) 3930 } 3931 3932 _preserved_marks_set.assert_empty(); 3933 3934 _allocator->release_gc_alloc_regions(evacuation_info); 3935 3936 merge_per_thread_state_info(per_thread_states); 3937 3938 // Reset and re-enable the hot card cache. 3939 // Note the counts for the cards in the regions in the 3940 // collection set are reset when the collection set is freed. 3941 _hot_card_cache->reset_hot_cache(); 3942 _hot_card_cache->set_use_cache(true); 3943 3944 purge_code_root_memory(); 3945 3946 redirty_logged_cards(); 3947 #if COMPILER2_OR_JVMCI 3948 double start = os::elapsedTime(); 3949 DerivedPointerTable::update_pointers(); 3950 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3951 #endif 3952 g1_policy()->print_age_table(); 3953 } 3954 3955 void G1CollectedHeap::record_obj_copy_mem_stats() { 3956 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3957 3958 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3959 create_g1_evac_summary(&_old_evac_stats)); 3960 } 3961 3962 void G1CollectedHeap::free_region(HeapRegion* hr, 3963 FreeRegionList* free_list, 3964 bool skip_remset, 3965 bool skip_hot_card_cache, 3966 bool locked) { 3967 assert(!hr->is_free(), "the region should not be free"); 3968 assert(!hr->is_empty(), "the region should not be empty"); 3969 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3970 assert(free_list != NULL, "pre-condition"); 3971 3972 if (G1VerifyBitmaps) { 3973 MemRegion mr(hr->bottom(), hr->end()); 3974 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3975 } 3976 3977 // Clear the card counts for this region. 3978 // Note: we only need to do this if the region is not young 3979 // (since we don't refine cards in young regions). 3980 if (!skip_hot_card_cache && !hr->is_young()) { 3981 _hot_card_cache->reset_card_counts(hr); 3982 } 3983 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3984 _g1_policy->remset_tracker()->update_at_free(hr); 3985 free_list->add_ordered(hr); 3986 } 3987 3988 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3989 FreeRegionList* free_list) { 3990 assert(hr->is_humongous(), "this is only for humongous regions"); 3991 assert(free_list != NULL, "pre-condition"); 3992 hr->clear_humongous(); 3993 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3994 } 3995 3996 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3997 const uint humongous_regions_removed) { 3998 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3999 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4000 _old_set.bulk_remove(old_regions_removed); 4001 _humongous_set.bulk_remove(humongous_regions_removed); 4002 } 4003 4004 } 4005 4006 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4007 assert(list != NULL, "list can't be null"); 4008 if (!list->is_empty()) { 4009 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4010 _hrm->insert_list_into_free_list(list); 4011 } 4012 } 4013 4014 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4015 decrease_used(bytes); 4016 } 4017 4018 class G1FreeCollectionSetTask : public AbstractGangTask { 4019 private: 4020 4021 // Closure applied to all regions in the collection set to do work that needs to 4022 // be done serially in a single thread. 4023 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4024 private: 4025 G1EvacuationInfo* _evacuation_info; 4026 const size_t* _surviving_young_words; 4027 4028 // Bytes used in successfully evacuated regions before the evacuation. 4029 size_t _before_used_bytes; 4030 // Bytes used in unsucessfully evacuated regions before the evacuation 4031 size_t _after_used_bytes; 4032 4033 size_t _bytes_allocated_in_old_since_last_gc; 4034 4035 size_t _failure_used_words; 4036 size_t _failure_waste_words; 4037 4038 FreeRegionList _local_free_list; 4039 public: 4040 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4041 HeapRegionClosure(), 4042 _evacuation_info(evacuation_info), 4043 _surviving_young_words(surviving_young_words), 4044 _before_used_bytes(0), 4045 _after_used_bytes(0), 4046 _bytes_allocated_in_old_since_last_gc(0), 4047 _failure_used_words(0), 4048 _failure_waste_words(0), 4049 _local_free_list("Local Region List for CSet Freeing") { 4050 } 4051 4052 virtual bool do_heap_region(HeapRegion* r) { 4053 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4054 4055 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4056 g1h->clear_in_cset(r); 4057 4058 if (r->is_young()) { 4059 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4060 "Young index %d is wrong for region %u of type %s with %u young regions", 4061 r->young_index_in_cset(), 4062 r->hrm_index(), 4063 r->get_type_str(), 4064 g1h->collection_set()->young_region_length()); 4065 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4066 r->record_surv_words_in_group(words_survived); 4067 } 4068 4069 if (!r->evacuation_failed()) { 4070 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4071 _before_used_bytes += r->used(); 4072 g1h->free_region(r, 4073 &_local_free_list, 4074 true, /* skip_remset */ 4075 true, /* skip_hot_card_cache */ 4076 true /* locked */); 4077 } else { 4078 r->uninstall_surv_rate_group(); 4079 r->set_young_index_in_cset(-1); 4080 r->set_evacuation_failed(false); 4081 // When moving a young gen region to old gen, we "allocate" that whole region 4082 // there. This is in addition to any already evacuated objects. Notify the 4083 // policy about that. 4084 // Old gen regions do not cause an additional allocation: both the objects 4085 // still in the region and the ones already moved are accounted for elsewhere. 4086 if (r->is_young()) { 4087 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4088 } 4089 // The region is now considered to be old. 4090 r->set_old(); 4091 // Do some allocation statistics accounting. Regions that failed evacuation 4092 // are always made old, so there is no need to update anything in the young 4093 // gen statistics, but we need to update old gen statistics. 4094 size_t used_words = r->marked_bytes() / HeapWordSize; 4095 4096 _failure_used_words += used_words; 4097 _failure_waste_words += HeapRegion::GrainWords - used_words; 4098 4099 g1h->old_set_add(r); 4100 _after_used_bytes += r->used(); 4101 } 4102 return false; 4103 } 4104 4105 void complete_work() { 4106 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4107 4108 _evacuation_info->set_regions_freed(_local_free_list.length()); 4109 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4110 4111 g1h->prepend_to_freelist(&_local_free_list); 4112 g1h->decrement_summary_bytes(_before_used_bytes); 4113 4114 G1Policy* policy = g1h->g1_policy(); 4115 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4116 4117 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4118 } 4119 }; 4120 4121 G1CollectionSet* _collection_set; 4122 G1SerialFreeCollectionSetClosure _cl; 4123 const size_t* _surviving_young_words; 4124 4125 size_t _rs_lengths; 4126 4127 volatile jint _serial_work_claim; 4128 4129 struct WorkItem { 4130 uint region_idx; 4131 bool is_young; 4132 bool evacuation_failed; 4133 4134 WorkItem(HeapRegion* r) { 4135 region_idx = r->hrm_index(); 4136 is_young = r->is_young(); 4137 evacuation_failed = r->evacuation_failed(); 4138 } 4139 }; 4140 4141 volatile size_t _parallel_work_claim; 4142 size_t _num_work_items; 4143 WorkItem* _work_items; 4144 4145 void do_serial_work() { 4146 // Need to grab the lock to be allowed to modify the old region list. 4147 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4148 _collection_set->iterate(&_cl); 4149 } 4150 4151 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4152 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4153 4154 HeapRegion* r = g1h->region_at(region_idx); 4155 assert(!g1h->is_on_master_free_list(r), "sanity"); 4156 4157 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4158 4159 if (!is_young) { 4160 g1h->_hot_card_cache->reset_card_counts(r); 4161 } 4162 4163 if (!evacuation_failed) { 4164 r->rem_set()->clear_locked(); 4165 } 4166 } 4167 4168 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4169 private: 4170 size_t _cur_idx; 4171 WorkItem* _work_items; 4172 public: 4173 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4174 4175 virtual bool do_heap_region(HeapRegion* r) { 4176 _work_items[_cur_idx++] = WorkItem(r); 4177 return false; 4178 } 4179 }; 4180 4181 void prepare_work() { 4182 G1PrepareFreeCollectionSetClosure cl(_work_items); 4183 _collection_set->iterate(&cl); 4184 } 4185 4186 void complete_work() { 4187 _cl.complete_work(); 4188 4189 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4190 policy->record_max_rs_lengths(_rs_lengths); 4191 policy->cset_regions_freed(); 4192 } 4193 public: 4194 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4195 AbstractGangTask("G1 Free Collection Set"), 4196 _collection_set(collection_set), 4197 _cl(evacuation_info, surviving_young_words), 4198 _surviving_young_words(surviving_young_words), 4199 _rs_lengths(0), 4200 _serial_work_claim(0), 4201 _parallel_work_claim(0), 4202 _num_work_items(collection_set->region_length()), 4203 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4204 prepare_work(); 4205 } 4206 4207 ~G1FreeCollectionSetTask() { 4208 complete_work(); 4209 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4210 } 4211 4212 // Chunk size for work distribution. The chosen value has been determined experimentally 4213 // to be a good tradeoff between overhead and achievable parallelism. 4214 static uint chunk_size() { return 32; } 4215 4216 virtual void work(uint worker_id) { 4217 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4218 4219 // Claim serial work. 4220 if (_serial_work_claim == 0) { 4221 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4222 if (value == 0) { 4223 double serial_time = os::elapsedTime(); 4224 do_serial_work(); 4225 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4226 } 4227 } 4228 4229 // Start parallel work. 4230 double young_time = 0.0; 4231 bool has_young_time = false; 4232 double non_young_time = 0.0; 4233 bool has_non_young_time = false; 4234 4235 while (true) { 4236 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4237 size_t cur = end - chunk_size(); 4238 4239 if (cur >= _num_work_items) { 4240 break; 4241 } 4242 4243 EventGCPhaseParallel event; 4244 double start_time = os::elapsedTime(); 4245 4246 end = MIN2(end, _num_work_items); 4247 4248 for (; cur < end; cur++) { 4249 bool is_young = _work_items[cur].is_young; 4250 4251 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4252 4253 double end_time = os::elapsedTime(); 4254 double time_taken = end_time - start_time; 4255 if (is_young) { 4256 young_time += time_taken; 4257 has_young_time = true; 4258 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4259 } else { 4260 non_young_time += time_taken; 4261 has_non_young_time = true; 4262 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4263 } 4264 start_time = end_time; 4265 } 4266 } 4267 4268 if (has_young_time) { 4269 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4270 } 4271 if (has_non_young_time) { 4272 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4273 } 4274 } 4275 }; 4276 4277 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4278 _eden.clear(); 4279 4280 double free_cset_start_time = os::elapsedTime(); 4281 4282 { 4283 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4284 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4285 4286 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4287 4288 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4289 cl.name(), 4290 num_workers, 4291 _collection_set.region_length()); 4292 workers()->run_task(&cl, num_workers); 4293 } 4294 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4295 4296 collection_set->clear(); 4297 } 4298 4299 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4300 private: 4301 FreeRegionList* _free_region_list; 4302 HeapRegionSet* _proxy_set; 4303 uint _humongous_objects_reclaimed; 4304 uint _humongous_regions_reclaimed; 4305 size_t _freed_bytes; 4306 public: 4307 4308 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4309 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4310 } 4311 4312 virtual bool do_heap_region(HeapRegion* r) { 4313 if (!r->is_starts_humongous()) { 4314 return false; 4315 } 4316 4317 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4318 4319 oop obj = (oop)r->bottom(); 4320 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4321 4322 // The following checks whether the humongous object is live are sufficient. 4323 // The main additional check (in addition to having a reference from the roots 4324 // or the young gen) is whether the humongous object has a remembered set entry. 4325 // 4326 // A humongous object cannot be live if there is no remembered set for it 4327 // because: 4328 // - there can be no references from within humongous starts regions referencing 4329 // the object because we never allocate other objects into them. 4330 // (I.e. there are no intra-region references that may be missed by the 4331 // remembered set) 4332 // - as soon there is a remembered set entry to the humongous starts region 4333 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4334 // until the end of a concurrent mark. 4335 // 4336 // It is not required to check whether the object has been found dead by marking 4337 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4338 // all objects allocated during that time are considered live. 4339 // SATB marking is even more conservative than the remembered set. 4340 // So if at this point in the collection there is no remembered set entry, 4341 // nobody has a reference to it. 4342 // At the start of collection we flush all refinement logs, and remembered sets 4343 // are completely up-to-date wrt to references to the humongous object. 4344 // 4345 // Other implementation considerations: 4346 // - never consider object arrays at this time because they would pose 4347 // considerable effort for cleaning up the the remembered sets. This is 4348 // required because stale remembered sets might reference locations that 4349 // are currently allocated into. 4350 uint region_idx = r->hrm_index(); 4351 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4352 !r->rem_set()->is_empty()) { 4353 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", 4354 region_idx, 4355 (size_t)obj->size() * HeapWordSize, 4356 p2i(r->bottom()), 4357 r->rem_set()->occupied(), 4358 r->rem_set()->strong_code_roots_list_length(), 4359 next_bitmap->is_marked(r->bottom()), 4360 g1h->is_humongous_reclaim_candidate(region_idx), 4361 obj->is_typeArray() 4362 ); 4363 return false; 4364 } 4365 4366 guarantee(obj->is_typeArray(), 4367 "Only eagerly reclaiming type arrays is supported, but the object " 4368 PTR_FORMAT " is not.", p2i(r->bottom())); 4369 4370 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", 4371 region_idx, 4372 (size_t)obj->size() * HeapWordSize, 4373 p2i(r->bottom()), 4374 r->rem_set()->occupied(), 4375 r->rem_set()->strong_code_roots_list_length(), 4376 next_bitmap->is_marked(r->bottom()), 4377 g1h->is_humongous_reclaim_candidate(region_idx), 4378 obj->is_typeArray() 4379 ); 4380 4381 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4382 cm->humongous_object_eagerly_reclaimed(r); 4383 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4384 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4385 region_idx, 4386 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4387 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4388 _humongous_objects_reclaimed++; 4389 do { 4390 HeapRegion* next = g1h->next_region_in_humongous(r); 4391 _freed_bytes += r->used(); 4392 r->set_containing_set(NULL); 4393 _humongous_regions_reclaimed++; 4394 g1h->free_humongous_region(r, _free_region_list); 4395 r = next; 4396 } while (r != NULL); 4397 4398 return false; 4399 } 4400 4401 uint humongous_objects_reclaimed() { 4402 return _humongous_objects_reclaimed; 4403 } 4404 4405 uint humongous_regions_reclaimed() { 4406 return _humongous_regions_reclaimed; 4407 } 4408 4409 size_t bytes_freed() const { 4410 return _freed_bytes; 4411 } 4412 }; 4413 4414 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4415 assert_at_safepoint_on_vm_thread(); 4416 4417 if (!G1EagerReclaimHumongousObjects || 4418 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4419 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4420 return; 4421 } 4422 4423 double start_time = os::elapsedTime(); 4424 4425 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4426 4427 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4428 heap_region_iterate(&cl); 4429 4430 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4431 4432 G1HRPrinter* hrp = hr_printer(); 4433 if (hrp->is_active()) { 4434 FreeRegionListIterator iter(&local_cleanup_list); 4435 while (iter.more_available()) { 4436 HeapRegion* hr = iter.get_next(); 4437 hrp->cleanup(hr); 4438 } 4439 } 4440 4441 prepend_to_freelist(&local_cleanup_list); 4442 decrement_summary_bytes(cl.bytes_freed()); 4443 4444 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4445 cl.humongous_objects_reclaimed()); 4446 } 4447 4448 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4449 public: 4450 virtual bool do_heap_region(HeapRegion* r) { 4451 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4452 G1CollectedHeap::heap()->clear_in_cset(r); 4453 r->set_young_index_in_cset(-1); 4454 return false; 4455 } 4456 }; 4457 4458 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4459 G1AbandonCollectionSetClosure cl; 4460 collection_set->iterate(&cl); 4461 4462 collection_set->clear(); 4463 collection_set->stop_incremental_building(); 4464 } 4465 4466 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4467 return _allocator->is_retained_old_region(hr); 4468 } 4469 4470 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4471 _eden.add(hr); 4472 _g1_policy->set_region_eden(hr); 4473 } 4474 4475 #ifdef ASSERT 4476 4477 class NoYoungRegionsClosure: public HeapRegionClosure { 4478 private: 4479 bool _success; 4480 public: 4481 NoYoungRegionsClosure() : _success(true) { } 4482 bool do_heap_region(HeapRegion* r) { 4483 if (r->is_young()) { 4484 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4485 p2i(r->bottom()), p2i(r->end())); 4486 _success = false; 4487 } 4488 return false; 4489 } 4490 bool success() { return _success; } 4491 }; 4492 4493 bool G1CollectedHeap::check_young_list_empty() { 4494 bool ret = (young_regions_count() == 0); 4495 4496 NoYoungRegionsClosure closure; 4497 heap_region_iterate(&closure); 4498 ret = ret && closure.success(); 4499 4500 return ret; 4501 } 4502 4503 #endif // ASSERT 4504 4505 class TearDownRegionSetsClosure : public HeapRegionClosure { 4506 HeapRegionSet *_old_set; 4507 4508 public: 4509 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4510 4511 bool do_heap_region(HeapRegion* r) { 4512 if (r->is_old()) { 4513 _old_set->remove(r); 4514 } else if(r->is_young()) { 4515 r->uninstall_surv_rate_group(); 4516 } else { 4517 // We ignore free regions, we'll empty the free list afterwards. 4518 // We ignore humongous and archive regions, we're not tearing down these 4519 // sets. 4520 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4521 "it cannot be another type"); 4522 } 4523 return false; 4524 } 4525 4526 ~TearDownRegionSetsClosure() { 4527 assert(_old_set->is_empty(), "post-condition"); 4528 } 4529 }; 4530 4531 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4532 assert_at_safepoint_on_vm_thread(); 4533 4534 if (!free_list_only) { 4535 TearDownRegionSetsClosure cl(&_old_set); 4536 heap_region_iterate(&cl); 4537 4538 // Note that emptying the _young_list is postponed and instead done as 4539 // the first step when rebuilding the regions sets again. The reason for 4540 // this is that during a full GC string deduplication needs to know if 4541 // a collected region was young or old when the full GC was initiated. 4542 } 4543 _hrm->remove_all_free_regions(); 4544 } 4545 4546 void G1CollectedHeap::increase_used(size_t bytes) { 4547 _summary_bytes_used += bytes; 4548 } 4549 4550 void G1CollectedHeap::decrease_used(size_t bytes) { 4551 assert(_summary_bytes_used >= bytes, 4552 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4553 _summary_bytes_used, bytes); 4554 _summary_bytes_used -= bytes; 4555 } 4556 4557 void G1CollectedHeap::set_used(size_t bytes) { 4558 _summary_bytes_used = bytes; 4559 } 4560 4561 class RebuildRegionSetsClosure : public HeapRegionClosure { 4562 private: 4563 bool _free_list_only; 4564 4565 HeapRegionSet* _old_set; 4566 HeapRegionManager* _hrm; 4567 4568 size_t _total_used; 4569 4570 public: 4571 RebuildRegionSetsClosure(bool free_list_only, 4572 HeapRegionSet* old_set, 4573 HeapRegionManager* hrm) : 4574 _free_list_only(free_list_only), 4575 _old_set(old_set), _hrm(hrm), _total_used(0) { 4576 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4577 if (!free_list_only) { 4578 assert(_old_set->is_empty(), "pre-condition"); 4579 } 4580 } 4581 4582 bool do_heap_region(HeapRegion* r) { 4583 if (r->is_empty()) { 4584 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4585 // Add free regions to the free list 4586 r->set_free(); 4587 _hrm->insert_into_free_list(r); 4588 } else if (!_free_list_only) { 4589 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4590 4591 if (r->is_archive() || r->is_humongous()) { 4592 // We ignore archive and humongous regions. We left these sets unchanged. 4593 } else { 4594 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4595 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4596 r->move_to_old(); 4597 _old_set->add(r); 4598 } 4599 _total_used += r->used(); 4600 } 4601 4602 return false; 4603 } 4604 4605 size_t total_used() { 4606 return _total_used; 4607 } 4608 }; 4609 4610 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4611 assert_at_safepoint_on_vm_thread(); 4612 4613 if (!free_list_only) { 4614 _eden.clear(); 4615 _survivor.clear(); 4616 } 4617 4618 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4619 heap_region_iterate(&cl); 4620 4621 if (!free_list_only) { 4622 set_used(cl.total_used()); 4623 if (_archive_allocator != NULL) { 4624 _archive_allocator->clear_used(); 4625 } 4626 } 4627 assert(used() == recalculate_used(), 4628 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4629 used(), recalculate_used()); 4630 } 4631 4632 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4633 HeapRegion* hr = heap_region_containing(p); 4634 return hr->is_in(p); 4635 } 4636 4637 // Methods for the mutator alloc region 4638 4639 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4640 bool force) { 4641 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4642 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4643 if (force || should_allocate) { 4644 HeapRegion* new_alloc_region = new_region(word_size, 4645 HeapRegionType::Eden, 4646 false /* do_expand */); 4647 if (new_alloc_region != NULL) { 4648 set_region_short_lived_locked(new_alloc_region); 4649 _hr_printer.alloc(new_alloc_region, !should_allocate); 4650 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4651 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4652 return new_alloc_region; 4653 } 4654 } 4655 return NULL; 4656 } 4657 4658 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4659 size_t allocated_bytes) { 4660 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4661 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4662 4663 collection_set()->add_eden_region(alloc_region); 4664 increase_used(allocated_bytes); 4665 _hr_printer.retire(alloc_region); 4666 // We update the eden sizes here, when the region is retired, 4667 // instead of when it's allocated, since this is the point that its 4668 // used space has been recorded in _summary_bytes_used. 4669 g1mm()->update_eden_size(); 4670 } 4671 4672 // Methods for the GC alloc regions 4673 4674 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4675 if (dest.is_old()) { 4676 return true; 4677 } else { 4678 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4679 } 4680 } 4681 4682 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4683 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4684 4685 if (!has_more_regions(dest)) { 4686 return NULL; 4687 } 4688 4689 HeapRegionType type; 4690 if (dest.is_young()) { 4691 type = HeapRegionType::Survivor; 4692 } else { 4693 type = HeapRegionType::Old; 4694 } 4695 4696 HeapRegion* new_alloc_region = new_region(word_size, 4697 type, 4698 true /* do_expand */); 4699 4700 if (new_alloc_region != NULL) { 4701 if (type.is_survivor()) { 4702 new_alloc_region->set_survivor(); 4703 _survivor.add(new_alloc_region); 4704 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4705 } else { 4706 new_alloc_region->set_old(); 4707 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4708 } 4709 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4710 _hr_printer.alloc(new_alloc_region); 4711 return new_alloc_region; 4712 } 4713 return NULL; 4714 } 4715 4716 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4717 size_t allocated_bytes, 4718 InCSetState dest) { 4719 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4720 if (dest.is_old()) { 4721 old_set_add(alloc_region); 4722 } 4723 4724 bool const during_im = collector_state()->in_initial_mark_gc(); 4725 if (during_im && allocated_bytes > 0) { 4726 _cm->root_regions()->add(alloc_region); 4727 } 4728 _hr_printer.retire(alloc_region); 4729 } 4730 4731 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4732 bool expanded = false; 4733 uint index = _hrm->find_highest_free(&expanded); 4734 4735 if (index != G1_NO_HRM_INDEX) { 4736 if (expanded) { 4737 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4738 HeapRegion::GrainWords * HeapWordSize); 4739 } 4740 _hrm->allocate_free_regions_starting_at(index, 1); 4741 return region_at(index); 4742 } 4743 return NULL; 4744 } 4745 4746 // Optimized nmethod scanning 4747 4748 class RegisterNMethodOopClosure: public OopClosure { 4749 G1CollectedHeap* _g1h; 4750 nmethod* _nm; 4751 4752 template <class T> void do_oop_work(T* p) { 4753 T heap_oop = RawAccess<>::oop_load(p); 4754 if (!CompressedOops::is_null(heap_oop)) { 4755 oop obj = CompressedOops::decode_not_null(heap_oop); 4756 HeapRegion* hr = _g1h->heap_region_containing(obj); 4757 assert(!hr->is_continues_humongous(), 4758 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4759 " starting at " HR_FORMAT, 4760 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4761 4762 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4763 hr->add_strong_code_root_locked(_nm); 4764 } 4765 } 4766 4767 public: 4768 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4769 _g1h(g1h), _nm(nm) {} 4770 4771 void do_oop(oop* p) { do_oop_work(p); } 4772 void do_oop(narrowOop* p) { do_oop_work(p); } 4773 }; 4774 4775 class UnregisterNMethodOopClosure: public OopClosure { 4776 G1CollectedHeap* _g1h; 4777 nmethod* _nm; 4778 4779 template <class T> void do_oop_work(T* p) { 4780 T heap_oop = RawAccess<>::oop_load(p); 4781 if (!CompressedOops::is_null(heap_oop)) { 4782 oop obj = CompressedOops::decode_not_null(heap_oop); 4783 HeapRegion* hr = _g1h->heap_region_containing(obj); 4784 assert(!hr->is_continues_humongous(), 4785 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4786 " starting at " HR_FORMAT, 4787 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4788 4789 hr->remove_strong_code_root(_nm); 4790 } 4791 } 4792 4793 public: 4794 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4795 _g1h(g1h), _nm(nm) {} 4796 4797 void do_oop(oop* p) { do_oop_work(p); } 4798 void do_oop(narrowOop* p) { do_oop_work(p); } 4799 }; 4800 4801 // Returns true if the reference points to an object that 4802 // can move in an incremental collection. 4803 bool G1CollectedHeap::is_scavengable(oop obj) { 4804 HeapRegion* hr = heap_region_containing(obj); 4805 return !hr->is_pinned(); 4806 } 4807 4808 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4809 guarantee(nm != NULL, "sanity"); 4810 RegisterNMethodOopClosure reg_cl(this, nm); 4811 nm->oops_do(®_cl); 4812 } 4813 4814 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4815 guarantee(nm != NULL, "sanity"); 4816 UnregisterNMethodOopClosure reg_cl(this, nm); 4817 nm->oops_do(®_cl, true); 4818 } 4819 4820 void G1CollectedHeap::purge_code_root_memory() { 4821 double purge_start = os::elapsedTime(); 4822 G1CodeRootSet::purge(); 4823 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4824 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4825 } 4826 4827 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4828 G1CollectedHeap* _g1h; 4829 4830 public: 4831 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4832 _g1h(g1h) {} 4833 4834 void do_code_blob(CodeBlob* cb) { 4835 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4836 if (nm == NULL) { 4837 return; 4838 } 4839 4840 if (ScavengeRootsInCode) { 4841 _g1h->register_nmethod(nm); 4842 } 4843 } 4844 }; 4845 4846 void G1CollectedHeap::rebuild_strong_code_roots() { 4847 RebuildStrongCodeRootClosure blob_cl(this); 4848 CodeCache::blobs_do(&blob_cl); 4849 } 4850 4851 void G1CollectedHeap::initialize_serviceability() { 4852 _g1mm->initialize_serviceability(); 4853 } 4854 4855 MemoryUsage G1CollectedHeap::memory_usage() { 4856 return _g1mm->memory_usage(); 4857 } 4858 4859 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4860 return _g1mm->memory_managers(); 4861 } 4862 4863 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4864 return _g1mm->memory_pools(); 4865 }