1 /* 2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/metadataOnStackMark.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/g1/g1Allocator.inline.hpp" 32 #include "gc/g1/g1BarrierSet.hpp" 33 #include "gc/g1/g1CollectedHeap.inline.hpp" 34 #include "gc/g1/g1CollectionSet.hpp" 35 #include "gc/g1/g1CollectorPolicy.hpp" 36 #include "gc/g1/g1CollectorState.hpp" 37 #include "gc/g1/g1ConcurrentRefine.hpp" 38 #include "gc/g1/g1ConcurrentRefineThread.hpp" 39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 40 #include "gc/g1/g1DirtyCardQueue.hpp" 41 #include "gc/g1/g1EvacStats.inline.hpp" 42 #include "gc/g1/g1FullCollector.hpp" 43 #include "gc/g1/g1GCPhaseTimes.hpp" 44 #include "gc/g1/g1HeapSizingPolicy.hpp" 45 #include "gc/g1/g1HeapTransition.hpp" 46 #include "gc/g1/g1HeapVerifier.hpp" 47 #include "gc/g1/g1HotCardCache.hpp" 48 #include "gc/g1/g1MemoryPool.hpp" 49 #include "gc/g1/g1OopClosures.inline.hpp" 50 #include "gc/g1/g1ParScanThreadState.inline.hpp" 51 #include "gc/g1/g1Policy.hpp" 52 #include "gc/g1/g1RegionToSpaceMapper.hpp" 53 #include "gc/g1/g1RemSet.hpp" 54 #include "gc/g1/g1RootClosures.hpp" 55 #include "gc/g1/g1RootProcessor.hpp" 56 #include "gc/g1/g1SATBMarkQueueSet.hpp" 57 #include "gc/g1/g1StringDedup.hpp" 58 #include "gc/g1/g1ThreadLocalData.hpp" 59 #include "gc/g1/g1YCTypes.hpp" 60 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 61 #include "gc/g1/g1VMOperations.hpp" 62 #include "gc/g1/heapRegion.inline.hpp" 63 #include "gc/g1/heapRegionRemSet.hpp" 64 #include "gc/g1/heapRegionSet.inline.hpp" 65 #include "gc/shared/gcBehaviours.hpp" 66 #include "gc/shared/gcHeapSummary.hpp" 67 #include "gc/shared/gcId.hpp" 68 #include "gc/shared/gcLocker.hpp" 69 #include "gc/shared/gcTimer.hpp" 70 #include "gc/shared/gcTrace.hpp" 71 #include "gc/shared/gcTraceTime.inline.hpp" 72 #include "gc/shared/generationSpec.hpp" 73 #include "gc/shared/isGCActiveMark.hpp" 74 #include "gc/shared/oopStorageParState.hpp" 75 #include "gc/shared/parallelCleaning.hpp" 76 #include "gc/shared/preservedMarks.inline.hpp" 77 #include "gc/shared/suspendibleThreadSet.hpp" 78 #include "gc/shared/referenceProcessor.inline.hpp" 79 #include "gc/shared/taskqueue.inline.hpp" 80 #include "gc/shared/weakProcessor.inline.hpp" 81 #include "gc/shared/workerPolicy.hpp" 82 #include "logging/log.hpp" 83 #include "memory/allocation.hpp" 84 #include "memory/iterator.hpp" 85 #include "memory/resourceArea.hpp" 86 #include "oops/access.inline.hpp" 87 #include "oops/compressedOops.inline.hpp" 88 #include "oops/oop.inline.hpp" 89 #include "runtime/atomic.hpp" 90 #include "runtime/flags/flagSetting.hpp" 91 #include "runtime/handles.inline.hpp" 92 #include "runtime/init.hpp" 93 #include "runtime/orderAccess.hpp" 94 #include "runtime/threadSMR.hpp" 95 #include "runtime/vmThread.hpp" 96 #include "utilities/align.hpp" 97 #include "utilities/globalDefinitions.hpp" 98 #include "utilities/stack.inline.hpp" 99 100 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 101 102 // INVARIANTS/NOTES 103 // 104 // All allocation activity covered by the G1CollectedHeap interface is 105 // serialized by acquiring the HeapLock. This happens in mem_allocate 106 // and allocate_new_tlab, which are the "entry" points to the 107 // allocation code from the rest of the JVM. (Note that this does not 108 // apply to TLAB allocation, which is not part of this interface: it 109 // is done by clients of this interface.) 110 111 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure { 112 private: 113 size_t _num_dirtied; 114 G1CollectedHeap* _g1h; 115 G1CardTable* _g1_ct; 116 117 HeapRegion* region_for_card(jbyte* card_ptr) const { 118 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 119 } 120 121 bool will_become_free(HeapRegion* hr) const { 122 // A region will be freed by free_collection_set if the region is in the 123 // collection set and has not had an evacuation failure. 124 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 125 } 126 127 public: 128 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(), 129 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 130 131 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 132 HeapRegion* hr = region_for_card(card_ptr); 133 134 // Should only dirty cards in regions that won't be freed. 135 if (!will_become_free(hr)) { 136 *card_ptr = G1CardTable::dirty_card_val(); 137 _num_dirtied++; 138 } 139 140 return true; 141 } 142 143 size_t num_dirtied() const { return _num_dirtied; } 144 }; 145 146 147 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 148 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 149 } 150 151 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 152 // The from card cache is not the memory that is actually committed. So we cannot 153 // take advantage of the zero_filled parameter. 154 reset_from_card_cache(start_idx, num_regions); 155 } 156 157 158 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 159 MemRegion mr) { 160 return new HeapRegion(hrs_index, bot(), mr); 161 } 162 163 // Private methods. 164 165 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) { 166 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 167 "the only time we use this to allocate a humongous region is " 168 "when we are allocating a single humongous region"); 169 170 HeapRegion* res = _hrm->allocate_free_region(type); 171 172 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 173 // Currently, only attempts to allocate GC alloc regions set 174 // do_expand to true. So, we should only reach here during a 175 // safepoint. If this assumption changes we might have to 176 // reconsider the use of _expand_heap_after_alloc_failure. 177 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 178 179 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 180 word_size * HeapWordSize); 181 182 if (expand(word_size * HeapWordSize)) { 183 // Given that expand() succeeded in expanding the heap, and we 184 // always expand the heap by an amount aligned to the heap 185 // region size, the free list should in theory not be empty. 186 // In either case allocate_free_region() will check for NULL. 187 res = _hrm->allocate_free_region(type); 188 } else { 189 _expand_heap_after_alloc_failure = false; 190 } 191 } 192 return res; 193 } 194 195 HeapWord* 196 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 197 uint num_regions, 198 size_t word_size) { 199 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 200 assert(is_humongous(word_size), "word_size should be humongous"); 201 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 202 203 // Index of last region in the series. 204 uint last = first + num_regions - 1; 205 206 // We need to initialize the region(s) we just discovered. This is 207 // a bit tricky given that it can happen concurrently with 208 // refinement threads refining cards on these regions and 209 // potentially wanting to refine the BOT as they are scanning 210 // those cards (this can happen shortly after a cleanup; see CR 211 // 6991377). So we have to set up the region(s) carefully and in 212 // a specific order. 213 214 // The word size sum of all the regions we will allocate. 215 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 216 assert(word_size <= word_size_sum, "sanity"); 217 218 // This will be the "starts humongous" region. 219 HeapRegion* first_hr = region_at(first); 220 // The header of the new object will be placed at the bottom of 221 // the first region. 222 HeapWord* new_obj = first_hr->bottom(); 223 // This will be the new top of the new object. 224 HeapWord* obj_top = new_obj + word_size; 225 226 // First, we need to zero the header of the space that we will be 227 // allocating. When we update top further down, some refinement 228 // threads might try to scan the region. By zeroing the header we 229 // ensure that any thread that will try to scan the region will 230 // come across the zero klass word and bail out. 231 // 232 // NOTE: It would not have been correct to have used 233 // CollectedHeap::fill_with_object() and make the space look like 234 // an int array. The thread that is doing the allocation will 235 // later update the object header to a potentially different array 236 // type and, for a very short period of time, the klass and length 237 // fields will be inconsistent. This could cause a refinement 238 // thread to calculate the object size incorrectly. 239 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 240 241 // Next, pad out the unused tail of the last region with filler 242 // objects, for improved usage accounting. 243 // How many words we use for filler objects. 244 size_t word_fill_size = word_size_sum - word_size; 245 246 // How many words memory we "waste" which cannot hold a filler object. 247 size_t words_not_fillable = 0; 248 249 if (word_fill_size >= min_fill_size()) { 250 fill_with_objects(obj_top, word_fill_size); 251 } else if (word_fill_size > 0) { 252 // We have space to fill, but we cannot fit an object there. 253 words_not_fillable = word_fill_size; 254 word_fill_size = 0; 255 } 256 257 // We will set up the first region as "starts humongous". This 258 // will also update the BOT covering all the regions to reflect 259 // that there is a single object that starts at the bottom of the 260 // first region. 261 first_hr->set_starts_humongous(obj_top, word_fill_size); 262 _g1_policy->remset_tracker()->update_at_allocate(first_hr); 263 // Then, if there are any, we will set up the "continues 264 // humongous" regions. 265 HeapRegion* hr = NULL; 266 for (uint i = first + 1; i <= last; ++i) { 267 hr = region_at(i); 268 hr->set_continues_humongous(first_hr); 269 _g1_policy->remset_tracker()->update_at_allocate(hr); 270 } 271 272 // Up to this point no concurrent thread would have been able to 273 // do any scanning on any region in this series. All the top 274 // fields still point to bottom, so the intersection between 275 // [bottom,top] and [card_start,card_end] will be empty. Before we 276 // update the top fields, we'll do a storestore to make sure that 277 // no thread sees the update to top before the zeroing of the 278 // object header and the BOT initialization. 279 OrderAccess::storestore(); 280 281 // Now, we will update the top fields of the "continues humongous" 282 // regions except the last one. 283 for (uint i = first; i < last; ++i) { 284 hr = region_at(i); 285 hr->set_top(hr->end()); 286 } 287 288 hr = region_at(last); 289 // If we cannot fit a filler object, we must set top to the end 290 // of the humongous object, otherwise we cannot iterate the heap 291 // and the BOT will not be complete. 292 hr->set_top(hr->end() - words_not_fillable); 293 294 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 295 "obj_top should be in last region"); 296 297 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 298 299 assert(words_not_fillable == 0 || 300 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 301 "Miscalculation in humongous allocation"); 302 303 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 304 305 for (uint i = first; i <= last; ++i) { 306 hr = region_at(i); 307 _humongous_set.add(hr); 308 _hr_printer.alloc(hr); 309 } 310 311 return new_obj; 312 } 313 314 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 315 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 316 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 317 } 318 319 // If could fit into free regions w/o expansion, try. 320 // Otherwise, if can expand, do so. 321 // Otherwise, if using ex regions might help, try with ex given back. 322 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 323 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 324 325 _verifier->verify_region_sets_optional(); 326 327 uint first = G1_NO_HRM_INDEX; 328 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 329 330 if (obj_regions == 1) { 331 // Only one region to allocate, try to use a fast path by directly allocating 332 // from the free lists. Do not try to expand here, we will potentially do that 333 // later. 334 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */); 335 if (hr != NULL) { 336 first = hr->hrm_index(); 337 } 338 } else { 339 // Policy: Try only empty regions (i.e. already committed first). Maybe we 340 // are lucky enough to find some. 341 first = _hrm->find_contiguous_only_empty(obj_regions); 342 if (first != G1_NO_HRM_INDEX) { 343 _hrm->allocate_free_regions_starting_at(first, obj_regions); 344 } 345 } 346 347 if (first == G1_NO_HRM_INDEX) { 348 // Policy: We could not find enough regions for the humongous object in the 349 // free list. Look through the heap to find a mix of free and uncommitted regions. 350 // If so, try expansion. 351 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions); 352 if (first != G1_NO_HRM_INDEX) { 353 // We found something. Make sure these regions are committed, i.e. expand 354 // the heap. Alternatively we could do a defragmentation GC. 355 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 356 word_size * HeapWordSize); 357 358 _hrm->expand_at(first, obj_regions, workers()); 359 g1_policy()->record_new_heap_size(num_regions()); 360 361 #ifdef ASSERT 362 for (uint i = first; i < first + obj_regions; ++i) { 363 HeapRegion* hr = region_at(i); 364 assert(hr->is_free(), "sanity"); 365 assert(hr->is_empty(), "sanity"); 366 assert(is_on_master_free_list(hr), "sanity"); 367 } 368 #endif 369 _hrm->allocate_free_regions_starting_at(first, obj_regions); 370 } else { 371 // Policy: Potentially trigger a defragmentation GC. 372 } 373 } 374 375 HeapWord* result = NULL; 376 if (first != G1_NO_HRM_INDEX) { 377 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 378 assert(result != NULL, "it should always return a valid result"); 379 380 // A successful humongous object allocation changes the used space 381 // information of the old generation so we need to recalculate the 382 // sizes and update the jstat counters here. 383 g1mm()->update_sizes(); 384 } 385 386 _verifier->verify_region_sets_optional(); 387 388 return result; 389 } 390 391 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 392 size_t requested_size, 393 size_t* actual_size) { 394 assert_heap_not_locked_and_not_at_safepoint(); 395 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 396 397 return attempt_allocation(min_size, requested_size, actual_size); 398 } 399 400 HeapWord* 401 G1CollectedHeap::mem_allocate(size_t word_size, 402 bool* gc_overhead_limit_was_exceeded) { 403 assert_heap_not_locked_and_not_at_safepoint(); 404 405 if (is_humongous(word_size)) { 406 return attempt_allocation_humongous(word_size); 407 } 408 size_t dummy = 0; 409 return attempt_allocation(word_size, word_size, &dummy); 410 } 411 412 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 413 ResourceMark rm; // For retrieving the thread names in log messages. 414 415 // Make sure you read the note in attempt_allocation_humongous(). 416 417 assert_heap_not_locked_and_not_at_safepoint(); 418 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 419 "be called for humongous allocation requests"); 420 421 // We should only get here after the first-level allocation attempt 422 // (attempt_allocation()) failed to allocate. 423 424 // We will loop until a) we manage to successfully perform the 425 // allocation or b) we successfully schedule a collection which 426 // fails to perform the allocation. b) is the only case when we'll 427 // return NULL. 428 HeapWord* result = NULL; 429 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 430 bool should_try_gc; 431 uint gc_count_before; 432 433 { 434 MutexLockerEx x(Heap_lock); 435 result = _allocator->attempt_allocation_locked(word_size); 436 if (result != NULL) { 437 return result; 438 } 439 440 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 441 // This is different to when only GCLocker::needs_gc() is set: try to avoid 442 // waiting because the GCLocker is active to not wait too long. 443 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 444 // No need for an ergo message here, can_expand_young_list() does this when 445 // it returns true. 446 result = _allocator->attempt_allocation_force(word_size); 447 if (result != NULL) { 448 return result; 449 } 450 } 451 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 452 // the GCLocker initiated GC has been performed and then retry. This includes 453 // the case when the GC Locker is not active but has not been performed. 454 should_try_gc = !GCLocker::needs_gc(); 455 // Read the GC count while still holding the Heap_lock. 456 gc_count_before = total_collections(); 457 } 458 459 if (should_try_gc) { 460 bool succeeded; 461 result = do_collection_pause(word_size, gc_count_before, &succeeded, 462 GCCause::_g1_inc_collection_pause); 463 if (result != NULL) { 464 assert(succeeded, "only way to get back a non-NULL result"); 465 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 466 Thread::current()->name(), p2i(result)); 467 return result; 468 } 469 470 if (succeeded) { 471 // We successfully scheduled a collection which failed to allocate. No 472 // point in trying to allocate further. We'll just return NULL. 473 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 474 SIZE_FORMAT " words", Thread::current()->name(), word_size); 475 return NULL; 476 } 477 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 478 Thread::current()->name(), word_size); 479 } else { 480 // Failed to schedule a collection. 481 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 482 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 483 SIZE_FORMAT " words", Thread::current()->name(), word_size); 484 return NULL; 485 } 486 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 487 // The GCLocker is either active or the GCLocker initiated 488 // GC has not yet been performed. Stall until it is and 489 // then retry the allocation. 490 GCLocker::stall_until_clear(); 491 gclocker_retry_count += 1; 492 } 493 494 // We can reach here if we were unsuccessful in scheduling a 495 // collection (because another thread beat us to it) or if we were 496 // stalled due to the GC locker. In either can we should retry the 497 // allocation attempt in case another thread successfully 498 // performed a collection and reclaimed enough space. We do the 499 // first attempt (without holding the Heap_lock) here and the 500 // follow-on attempt will be at the start of the next loop 501 // iteration (after taking the Heap_lock). 502 size_t dummy = 0; 503 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 504 if (result != NULL) { 505 return result; 506 } 507 508 // Give a warning if we seem to be looping forever. 509 if ((QueuedAllocationWarningCount > 0) && 510 (try_count % QueuedAllocationWarningCount == 0)) { 511 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 512 Thread::current()->name(), try_count, word_size); 513 } 514 } 515 516 ShouldNotReachHere(); 517 return NULL; 518 } 519 520 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 521 assert_at_safepoint_on_vm_thread(); 522 if (_archive_allocator == NULL) { 523 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 524 } 525 } 526 527 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 528 // Allocations in archive regions cannot be of a size that would be considered 529 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 530 // may be different at archive-restore time. 531 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 532 } 533 534 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 535 assert_at_safepoint_on_vm_thread(); 536 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 537 if (is_archive_alloc_too_large(word_size)) { 538 return NULL; 539 } 540 return _archive_allocator->archive_mem_allocate(word_size); 541 } 542 543 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 544 size_t end_alignment_in_bytes) { 545 assert_at_safepoint_on_vm_thread(); 546 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 547 548 // Call complete_archive to do the real work, filling in the MemRegion 549 // array with the archive regions. 550 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 551 delete _archive_allocator; 552 _archive_allocator = NULL; 553 } 554 555 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 556 assert(ranges != NULL, "MemRegion array NULL"); 557 assert(count != 0, "No MemRegions provided"); 558 MemRegion reserved = _hrm->reserved(); 559 for (size_t i = 0; i < count; i++) { 560 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 561 return false; 562 } 563 } 564 return true; 565 } 566 567 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 568 size_t count, 569 bool open) { 570 assert(!is_init_completed(), "Expect to be called at JVM init time"); 571 assert(ranges != NULL, "MemRegion array NULL"); 572 assert(count != 0, "No MemRegions provided"); 573 MutexLockerEx x(Heap_lock); 574 575 MemRegion reserved = _hrm->reserved(); 576 HeapWord* prev_last_addr = NULL; 577 HeapRegion* prev_last_region = NULL; 578 579 // Temporarily disable pretouching of heap pages. This interface is used 580 // when mmap'ing archived heap data in, so pre-touching is wasted. 581 FlagSetting fs(AlwaysPreTouch, false); 582 583 // Enable archive object checking used by G1MarkSweep. We have to let it know 584 // about each archive range, so that objects in those ranges aren't marked. 585 G1ArchiveAllocator::enable_archive_object_check(); 586 587 // For each specified MemRegion range, allocate the corresponding G1 588 // regions and mark them as archive regions. We expect the ranges 589 // in ascending starting address order, without overlap. 590 for (size_t i = 0; i < count; i++) { 591 MemRegion curr_range = ranges[i]; 592 HeapWord* start_address = curr_range.start(); 593 size_t word_size = curr_range.word_size(); 594 HeapWord* last_address = curr_range.last(); 595 size_t commits = 0; 596 597 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 598 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 599 p2i(start_address), p2i(last_address)); 600 guarantee(start_address > prev_last_addr, 601 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 602 p2i(start_address), p2i(prev_last_addr)); 603 prev_last_addr = last_address; 604 605 // Check for ranges that start in the same G1 region in which the previous 606 // range ended, and adjust the start address so we don't try to allocate 607 // the same region again. If the current range is entirely within that 608 // region, skip it, just adjusting the recorded top. 609 HeapRegion* start_region = _hrm->addr_to_region(start_address); 610 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 611 start_address = start_region->end(); 612 if (start_address > last_address) { 613 increase_used(word_size * HeapWordSize); 614 start_region->set_top(last_address + 1); 615 continue; 616 } 617 start_region->set_top(start_address); 618 curr_range = MemRegion(start_address, last_address + 1); 619 start_region = _hrm->addr_to_region(start_address); 620 } 621 622 // Perform the actual region allocation, exiting if it fails. 623 // Then note how much new space we have allocated. 624 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) { 625 return false; 626 } 627 increase_used(word_size * HeapWordSize); 628 if (commits != 0) { 629 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 630 HeapRegion::GrainWords * HeapWordSize * commits); 631 632 } 633 634 // Mark each G1 region touched by the range as archive, add it to 635 // the old set, and set top. 636 HeapRegion* curr_region = _hrm->addr_to_region(start_address); 637 HeapRegion* last_region = _hrm->addr_to_region(last_address); 638 prev_last_region = last_region; 639 640 while (curr_region != NULL) { 641 assert(curr_region->is_empty() && !curr_region->is_pinned(), 642 "Region already in use (index %u)", curr_region->hrm_index()); 643 if (open) { 644 curr_region->set_open_archive(); 645 } else { 646 curr_region->set_closed_archive(); 647 } 648 _hr_printer.alloc(curr_region); 649 _archive_set.add(curr_region); 650 HeapWord* top; 651 HeapRegion* next_region; 652 if (curr_region != last_region) { 653 top = curr_region->end(); 654 next_region = _hrm->next_region_in_heap(curr_region); 655 } else { 656 top = last_address + 1; 657 next_region = NULL; 658 } 659 curr_region->set_top(top); 660 curr_region->set_first_dead(top); 661 curr_region->set_end_of_live(top); 662 curr_region = next_region; 663 } 664 665 // Notify mark-sweep of the archive 666 G1ArchiveAllocator::set_range_archive(curr_range, open); 667 } 668 return true; 669 } 670 671 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 672 assert(!is_init_completed(), "Expect to be called at JVM init time"); 673 assert(ranges != NULL, "MemRegion array NULL"); 674 assert(count != 0, "No MemRegions provided"); 675 MemRegion reserved = _hrm->reserved(); 676 HeapWord *prev_last_addr = NULL; 677 HeapRegion* prev_last_region = NULL; 678 679 // For each MemRegion, create filler objects, if needed, in the G1 regions 680 // that contain the address range. The address range actually within the 681 // MemRegion will not be modified. That is assumed to have been initialized 682 // elsewhere, probably via an mmap of archived heap data. 683 MutexLockerEx x(Heap_lock); 684 for (size_t i = 0; i < count; i++) { 685 HeapWord* start_address = ranges[i].start(); 686 HeapWord* last_address = ranges[i].last(); 687 688 assert(reserved.contains(start_address) && reserved.contains(last_address), 689 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 690 p2i(start_address), p2i(last_address)); 691 assert(start_address > prev_last_addr, 692 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 693 p2i(start_address), p2i(prev_last_addr)); 694 695 HeapRegion* start_region = _hrm->addr_to_region(start_address); 696 HeapRegion* last_region = _hrm->addr_to_region(last_address); 697 HeapWord* bottom_address = start_region->bottom(); 698 699 // Check for a range beginning in the same region in which the 700 // previous one ended. 701 if (start_region == prev_last_region) { 702 bottom_address = prev_last_addr + 1; 703 } 704 705 // Verify that the regions were all marked as archive regions by 706 // alloc_archive_regions. 707 HeapRegion* curr_region = start_region; 708 while (curr_region != NULL) { 709 guarantee(curr_region->is_archive(), 710 "Expected archive region at index %u", curr_region->hrm_index()); 711 if (curr_region != last_region) { 712 curr_region = _hrm->next_region_in_heap(curr_region); 713 } else { 714 curr_region = NULL; 715 } 716 } 717 718 prev_last_addr = last_address; 719 prev_last_region = last_region; 720 721 // Fill the memory below the allocated range with dummy object(s), 722 // if the region bottom does not match the range start, or if the previous 723 // range ended within the same G1 region, and there is a gap. 724 if (start_address != bottom_address) { 725 size_t fill_size = pointer_delta(start_address, bottom_address); 726 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 727 increase_used(fill_size * HeapWordSize); 728 } 729 } 730 } 731 732 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 733 size_t desired_word_size, 734 size_t* actual_word_size) { 735 assert_heap_not_locked_and_not_at_safepoint(); 736 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 737 "be called for humongous allocation requests"); 738 739 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 740 741 if (result == NULL) { 742 *actual_word_size = desired_word_size; 743 result = attempt_allocation_slow(desired_word_size); 744 } 745 746 assert_heap_not_locked(); 747 if (result != NULL) { 748 assert(*actual_word_size != 0, "Actual size must have been set here"); 749 dirty_young_block(result, *actual_word_size); 750 } else { 751 *actual_word_size = 0; 752 } 753 754 return result; 755 } 756 757 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 758 assert(!is_init_completed(), "Expect to be called at JVM init time"); 759 assert(ranges != NULL, "MemRegion array NULL"); 760 assert(count != 0, "No MemRegions provided"); 761 MemRegion reserved = _hrm->reserved(); 762 HeapWord* prev_last_addr = NULL; 763 HeapRegion* prev_last_region = NULL; 764 size_t size_used = 0; 765 size_t uncommitted_regions = 0; 766 767 // For each Memregion, free the G1 regions that constitute it, and 768 // notify mark-sweep that the range is no longer to be considered 'archive.' 769 MutexLockerEx x(Heap_lock); 770 for (size_t i = 0; i < count; i++) { 771 HeapWord* start_address = ranges[i].start(); 772 HeapWord* last_address = ranges[i].last(); 773 774 assert(reserved.contains(start_address) && reserved.contains(last_address), 775 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 776 p2i(start_address), p2i(last_address)); 777 assert(start_address > prev_last_addr, 778 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 779 p2i(start_address), p2i(prev_last_addr)); 780 size_used += ranges[i].byte_size(); 781 prev_last_addr = last_address; 782 783 HeapRegion* start_region = _hrm->addr_to_region(start_address); 784 HeapRegion* last_region = _hrm->addr_to_region(last_address); 785 786 // Check for ranges that start in the same G1 region in which the previous 787 // range ended, and adjust the start address so we don't try to free 788 // the same region again. If the current range is entirely within that 789 // region, skip it. 790 if (start_region == prev_last_region) { 791 start_address = start_region->end(); 792 if (start_address > last_address) { 793 continue; 794 } 795 start_region = _hrm->addr_to_region(start_address); 796 } 797 prev_last_region = last_region; 798 799 // After verifying that each region was marked as an archive region by 800 // alloc_archive_regions, set it free and empty and uncommit it. 801 HeapRegion* curr_region = start_region; 802 while (curr_region != NULL) { 803 guarantee(curr_region->is_archive(), 804 "Expected archive region at index %u", curr_region->hrm_index()); 805 uint curr_index = curr_region->hrm_index(); 806 _archive_set.remove(curr_region); 807 curr_region->set_free(); 808 curr_region->set_top(curr_region->bottom()); 809 if (curr_region != last_region) { 810 curr_region = _hrm->next_region_in_heap(curr_region); 811 } else { 812 curr_region = NULL; 813 } 814 _hrm->shrink_at(curr_index, 1); 815 uncommitted_regions++; 816 } 817 818 // Notify mark-sweep that this is no longer an archive range. 819 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 820 } 821 822 if (uncommitted_regions != 0) { 823 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 824 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 825 } 826 decrease_used(size_used); 827 } 828 829 oop G1CollectedHeap::materialize_archived_object(oop obj) { 830 assert(obj != NULL, "archived obj is NULL"); 831 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 832 833 // Loading an archived object makes it strongly reachable. If it is 834 // loaded during concurrent marking, it must be enqueued to the SATB 835 // queue, shading the previously white object gray. 836 G1BarrierSet::enqueue(obj); 837 838 return obj; 839 } 840 841 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 842 ResourceMark rm; // For retrieving the thread names in log messages. 843 844 // The structure of this method has a lot of similarities to 845 // attempt_allocation_slow(). The reason these two were not merged 846 // into a single one is that such a method would require several "if 847 // allocation is not humongous do this, otherwise do that" 848 // conditional paths which would obscure its flow. In fact, an early 849 // version of this code did use a unified method which was harder to 850 // follow and, as a result, it had subtle bugs that were hard to 851 // track down. So keeping these two methods separate allows each to 852 // be more readable. It will be good to keep these two in sync as 853 // much as possible. 854 855 assert_heap_not_locked_and_not_at_safepoint(); 856 assert(is_humongous(word_size), "attempt_allocation_humongous() " 857 "should only be called for humongous allocations"); 858 859 // Humongous objects can exhaust the heap quickly, so we should check if we 860 // need to start a marking cycle at each humongous object allocation. We do 861 // the check before we do the actual allocation. The reason for doing it 862 // before the allocation is that we avoid having to keep track of the newly 863 // allocated memory while we do a GC. 864 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 865 word_size)) { 866 collect(GCCause::_g1_humongous_allocation); 867 } 868 869 // We will loop until a) we manage to successfully perform the 870 // allocation or b) we successfully schedule a collection which 871 // fails to perform the allocation. b) is the only case when we'll 872 // return NULL. 873 HeapWord* result = NULL; 874 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 875 bool should_try_gc; 876 uint gc_count_before; 877 878 879 { 880 MutexLockerEx x(Heap_lock); 881 882 // Given that humongous objects are not allocated in young 883 // regions, we'll first try to do the allocation without doing a 884 // collection hoping that there's enough space in the heap. 885 result = humongous_obj_allocate(word_size); 886 if (result != NULL) { 887 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 888 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 889 return result; 890 } 891 892 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 893 // the GCLocker initiated GC has been performed and then retry. This includes 894 // the case when the GC Locker is not active but has not been performed. 895 should_try_gc = !GCLocker::needs_gc(); 896 // Read the GC count while still holding the Heap_lock. 897 gc_count_before = total_collections(); 898 } 899 900 if (should_try_gc) { 901 bool succeeded; 902 result = do_collection_pause(word_size, gc_count_before, &succeeded, 903 GCCause::_g1_humongous_allocation); 904 if (result != NULL) { 905 assert(succeeded, "only way to get back a non-NULL result"); 906 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 907 Thread::current()->name(), p2i(result)); 908 return result; 909 } 910 911 if (succeeded) { 912 // We successfully scheduled a collection which failed to allocate. No 913 // point in trying to allocate further. We'll just return NULL. 914 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 915 SIZE_FORMAT " words", Thread::current()->name(), word_size); 916 return NULL; 917 } 918 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 919 Thread::current()->name(), word_size); 920 } else { 921 // Failed to schedule a collection. 922 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 923 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 924 SIZE_FORMAT " words", Thread::current()->name(), word_size); 925 return NULL; 926 } 927 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 928 // The GCLocker is either active or the GCLocker initiated 929 // GC has not yet been performed. Stall until it is and 930 // then retry the allocation. 931 GCLocker::stall_until_clear(); 932 gclocker_retry_count += 1; 933 } 934 935 936 // We can reach here if we were unsuccessful in scheduling a 937 // collection (because another thread beat us to it) or if we were 938 // stalled due to the GC locker. In either can we should retry the 939 // allocation attempt in case another thread successfully 940 // performed a collection and reclaimed enough space. 941 // Humongous object allocation always needs a lock, so we wait for the retry 942 // in the next iteration of the loop, unlike for the regular iteration case. 943 // Give a warning if we seem to be looping forever. 944 945 if ((QueuedAllocationWarningCount > 0) && 946 (try_count % QueuedAllocationWarningCount == 0)) { 947 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 948 Thread::current()->name(), try_count, word_size); 949 } 950 } 951 952 ShouldNotReachHere(); 953 return NULL; 954 } 955 956 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 957 bool expect_null_mutator_alloc_region) { 958 assert_at_safepoint_on_vm_thread(); 959 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 960 "the current alloc region was unexpectedly found to be non-NULL"); 961 962 if (!is_humongous(word_size)) { 963 return _allocator->attempt_allocation_locked(word_size); 964 } else { 965 HeapWord* result = humongous_obj_allocate(word_size); 966 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 967 collector_state()->set_initiate_conc_mark_if_possible(true); 968 } 969 return result; 970 } 971 972 ShouldNotReachHere(); 973 } 974 975 class PostCompactionPrinterClosure: public HeapRegionClosure { 976 private: 977 G1HRPrinter* _hr_printer; 978 public: 979 bool do_heap_region(HeapRegion* hr) { 980 assert(!hr->is_young(), "not expecting to find young regions"); 981 _hr_printer->post_compaction(hr); 982 return false; 983 } 984 985 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 986 : _hr_printer(hr_printer) { } 987 }; 988 989 void G1CollectedHeap::print_hrm_post_compaction() { 990 if (_hr_printer.is_active()) { 991 PostCompactionPrinterClosure cl(hr_printer()); 992 heap_region_iterate(&cl); 993 } 994 } 995 996 void G1CollectedHeap::abort_concurrent_cycle() { 997 // If we start the compaction before the CM threads finish 998 // scanning the root regions we might trip them over as we'll 999 // be moving objects / updating references. So let's wait until 1000 // they are done. By telling them to abort, they should complete 1001 // early. 1002 _cm->root_regions()->abort(); 1003 _cm->root_regions()->wait_until_scan_finished(); 1004 1005 // Disable discovery and empty the discovered lists 1006 // for the CM ref processor. 1007 _ref_processor_cm->disable_discovery(); 1008 _ref_processor_cm->abandon_partial_discovery(); 1009 _ref_processor_cm->verify_no_references_recorded(); 1010 1011 // Abandon current iterations of concurrent marking and concurrent 1012 // refinement, if any are in progress. 1013 concurrent_mark()->concurrent_cycle_abort(); 1014 } 1015 1016 void G1CollectedHeap::prepare_heap_for_full_collection() { 1017 // Make sure we'll choose a new allocation region afterwards. 1018 _allocator->release_mutator_alloc_region(); 1019 _allocator->abandon_gc_alloc_regions(); 1020 1021 // We may have added regions to the current incremental collection 1022 // set between the last GC or pause and now. We need to clear the 1023 // incremental collection set and then start rebuilding it afresh 1024 // after this full GC. 1025 abandon_collection_set(collection_set()); 1026 1027 tear_down_region_sets(false /* free_list_only */); 1028 1029 hrm()->prepare_for_full_collection_start(); 1030 } 1031 1032 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1033 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1034 assert(used() == recalculate_used(), "Should be equal"); 1035 _verifier->verify_region_sets_optional(); 1036 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1037 _verifier->check_bitmaps("Full GC Start"); 1038 } 1039 1040 void G1CollectedHeap::prepare_heap_for_mutators() { 1041 hrm()->prepare_for_full_collection_end(); 1042 1043 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1044 ClassLoaderDataGraph::purge(); 1045 MetaspaceUtils::verify_metrics(); 1046 1047 // Prepare heap for normal collections. 1048 assert(num_free_regions() == 0, "we should not have added any free regions"); 1049 rebuild_region_sets(false /* free_list_only */); 1050 abort_refinement(); 1051 resize_heap_if_necessary(); 1052 1053 // Rebuild the strong code root lists for each region 1054 rebuild_strong_code_roots(); 1055 1056 // Purge code root memory 1057 purge_code_root_memory(); 1058 1059 // Start a new incremental collection set for the next pause 1060 start_new_collection_set(); 1061 1062 _allocator->init_mutator_alloc_region(); 1063 1064 // Post collection state updates. 1065 MetaspaceGC::compute_new_size(); 1066 } 1067 1068 void G1CollectedHeap::abort_refinement() { 1069 if (_hot_card_cache->use_cache()) { 1070 _hot_card_cache->reset_hot_cache(); 1071 } 1072 1073 // Discard all remembered set updates. 1074 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1075 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1076 } 1077 1078 void G1CollectedHeap::verify_after_full_collection() { 1079 _hrm->verify_optional(); 1080 _verifier->verify_region_sets_optional(); 1081 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1082 // Clear the previous marking bitmap, if needed for bitmap verification. 1083 // Note we cannot do this when we clear the next marking bitmap in 1084 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1085 // objects marked during a full GC against the previous bitmap. 1086 // But we need to clear it before calling check_bitmaps below since 1087 // the full GC has compacted objects and updated TAMS but not updated 1088 // the prev bitmap. 1089 if (G1VerifyBitmaps) { 1090 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification"); 1091 _cm->clear_prev_bitmap(workers()); 1092 } 1093 // This call implicitly verifies that the next bitmap is clear after Full GC. 1094 _verifier->check_bitmaps("Full GC End"); 1095 1096 // At this point there should be no regions in the 1097 // entire heap tagged as young. 1098 assert(check_young_list_empty(), "young list should be empty at this point"); 1099 1100 // Note: since we've just done a full GC, concurrent 1101 // marking is no longer active. Therefore we need not 1102 // re-enable reference discovery for the CM ref processor. 1103 // That will be done at the start of the next marking cycle. 1104 // We also know that the STW processor should no longer 1105 // discover any new references. 1106 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1107 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1108 _ref_processor_stw->verify_no_references_recorded(); 1109 _ref_processor_cm->verify_no_references_recorded(); 1110 } 1111 1112 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1113 // Post collection logging. 1114 // We should do this after we potentially resize the heap so 1115 // that all the COMMIT / UNCOMMIT events are generated before 1116 // the compaction events. 1117 print_hrm_post_compaction(); 1118 heap_transition->print(); 1119 print_heap_after_gc(); 1120 print_heap_regions(); 1121 #ifdef TRACESPINNING 1122 ParallelTaskTerminator::print_termination_counts(); 1123 #endif 1124 } 1125 1126 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1127 bool clear_all_soft_refs) { 1128 assert_at_safepoint_on_vm_thread(); 1129 1130 if (GCLocker::check_active_before_gc()) { 1131 // Full GC was not completed. 1132 return false; 1133 } 1134 1135 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1136 soft_ref_policy()->should_clear_all_soft_refs(); 1137 1138 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1139 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1140 1141 collector.prepare_collection(); 1142 collector.collect(); 1143 collector.complete_collection(); 1144 1145 // Full collection was successfully completed. 1146 return true; 1147 } 1148 1149 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1150 // Currently, there is no facility in the do_full_collection(bool) API to notify 1151 // the caller that the collection did not succeed (e.g., because it was locked 1152 // out by the GC locker). So, right now, we'll ignore the return value. 1153 bool dummy = do_full_collection(true, /* explicit_gc */ 1154 clear_all_soft_refs); 1155 } 1156 1157 void G1CollectedHeap::resize_heap_if_necessary() { 1158 assert_at_safepoint_on_vm_thread(); 1159 1160 // Capacity, free and used after the GC counted as full regions to 1161 // include the waste in the following calculations. 1162 const size_t capacity_after_gc = capacity(); 1163 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1164 1165 // This is enforced in arguments.cpp. 1166 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1167 "otherwise the code below doesn't make sense"); 1168 1169 // We don't have floating point command-line arguments 1170 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1171 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1172 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1173 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1174 1175 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1176 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1177 1178 // We have to be careful here as these two calculations can overflow 1179 // 32-bit size_t's. 1180 double used_after_gc_d = (double) used_after_gc; 1181 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1182 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1183 1184 // Let's make sure that they are both under the max heap size, which 1185 // by default will make them fit into a size_t. 1186 double desired_capacity_upper_bound = (double) max_heap_size; 1187 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1188 desired_capacity_upper_bound); 1189 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1190 desired_capacity_upper_bound); 1191 1192 // We can now safely turn them into size_t's. 1193 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1194 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1195 1196 // This assert only makes sense here, before we adjust them 1197 // with respect to the min and max heap size. 1198 assert(minimum_desired_capacity <= maximum_desired_capacity, 1199 "minimum_desired_capacity = " SIZE_FORMAT ", " 1200 "maximum_desired_capacity = " SIZE_FORMAT, 1201 minimum_desired_capacity, maximum_desired_capacity); 1202 1203 // Should not be greater than the heap max size. No need to adjust 1204 // it with respect to the heap min size as it's a lower bound (i.e., 1205 // we'll try to make the capacity larger than it, not smaller). 1206 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1207 // Should not be less than the heap min size. No need to adjust it 1208 // with respect to the heap max size as it's an upper bound (i.e., 1209 // we'll try to make the capacity smaller than it, not greater). 1210 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1211 1212 if (capacity_after_gc < minimum_desired_capacity) { 1213 // Don't expand unless it's significant 1214 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1215 1216 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1217 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1218 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1219 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1220 1221 expand(expand_bytes, _workers); 1222 1223 // No expansion, now see if we want to shrink 1224 } else if (capacity_after_gc > maximum_desired_capacity) { 1225 // Capacity too large, compute shrinking size 1226 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1227 1228 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1229 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1230 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1231 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1232 1233 shrink(shrink_bytes); 1234 } 1235 } 1236 1237 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1238 bool do_gc, 1239 bool clear_all_soft_refs, 1240 bool expect_null_mutator_alloc_region, 1241 bool* gc_succeeded) { 1242 *gc_succeeded = true; 1243 // Let's attempt the allocation first. 1244 HeapWord* result = 1245 attempt_allocation_at_safepoint(word_size, 1246 expect_null_mutator_alloc_region); 1247 if (result != NULL) { 1248 return result; 1249 } 1250 1251 // In a G1 heap, we're supposed to keep allocation from failing by 1252 // incremental pauses. Therefore, at least for now, we'll favor 1253 // expansion over collection. (This might change in the future if we can 1254 // do something smarter than full collection to satisfy a failed alloc.) 1255 result = expand_and_allocate(word_size); 1256 if (result != NULL) { 1257 return result; 1258 } 1259 1260 if (do_gc) { 1261 // Expansion didn't work, we'll try to do a Full GC. 1262 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1263 clear_all_soft_refs); 1264 } 1265 1266 return NULL; 1267 } 1268 1269 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1270 bool* succeeded) { 1271 assert_at_safepoint_on_vm_thread(); 1272 1273 // Attempts to allocate followed by Full GC. 1274 HeapWord* result = 1275 satisfy_failed_allocation_helper(word_size, 1276 true, /* do_gc */ 1277 false, /* clear_all_soft_refs */ 1278 false, /* expect_null_mutator_alloc_region */ 1279 succeeded); 1280 1281 if (result != NULL || !*succeeded) { 1282 return result; 1283 } 1284 1285 // Attempts to allocate followed by Full GC that will collect all soft references. 1286 result = satisfy_failed_allocation_helper(word_size, 1287 true, /* do_gc */ 1288 true, /* clear_all_soft_refs */ 1289 true, /* expect_null_mutator_alloc_region */ 1290 succeeded); 1291 1292 if (result != NULL || !*succeeded) { 1293 return result; 1294 } 1295 1296 // Attempts to allocate, no GC 1297 result = satisfy_failed_allocation_helper(word_size, 1298 false, /* do_gc */ 1299 false, /* clear_all_soft_refs */ 1300 true, /* expect_null_mutator_alloc_region */ 1301 succeeded); 1302 1303 if (result != NULL) { 1304 return result; 1305 } 1306 1307 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1308 "Flag should have been handled and cleared prior to this point"); 1309 1310 // What else? We might try synchronous finalization later. If the total 1311 // space available is large enough for the allocation, then a more 1312 // complete compaction phase than we've tried so far might be 1313 // appropriate. 1314 return NULL; 1315 } 1316 1317 // Attempting to expand the heap sufficiently 1318 // to support an allocation of the given "word_size". If 1319 // successful, perform the allocation and return the address of the 1320 // allocated block, or else "NULL". 1321 1322 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1323 assert_at_safepoint_on_vm_thread(); 1324 1325 _verifier->verify_region_sets_optional(); 1326 1327 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1328 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1329 word_size * HeapWordSize); 1330 1331 1332 if (expand(expand_bytes, _workers)) { 1333 _hrm->verify_optional(); 1334 _verifier->verify_region_sets_optional(); 1335 return attempt_allocation_at_safepoint(word_size, 1336 false /* expect_null_mutator_alloc_region */); 1337 } 1338 return NULL; 1339 } 1340 1341 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1342 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1343 aligned_expand_bytes = align_up(aligned_expand_bytes, 1344 HeapRegion::GrainBytes); 1345 1346 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1347 expand_bytes, aligned_expand_bytes); 1348 1349 if (is_maximal_no_gc()) { 1350 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1351 return false; 1352 } 1353 1354 double expand_heap_start_time_sec = os::elapsedTime(); 1355 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1356 assert(regions_to_expand > 0, "Must expand by at least one region"); 1357 1358 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1359 if (expand_time_ms != NULL) { 1360 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1361 } 1362 1363 if (expanded_by > 0) { 1364 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1365 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1366 g1_policy()->record_new_heap_size(num_regions()); 1367 } else { 1368 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1369 1370 // The expansion of the virtual storage space was unsuccessful. 1371 // Let's see if it was because we ran out of swap. 1372 if (G1ExitOnExpansionFailure && 1373 _hrm->available() >= regions_to_expand) { 1374 // We had head room... 1375 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1376 } 1377 } 1378 return regions_to_expand > 0; 1379 } 1380 1381 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1382 size_t aligned_shrink_bytes = 1383 ReservedSpace::page_align_size_down(shrink_bytes); 1384 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1385 HeapRegion::GrainBytes); 1386 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1387 1388 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1389 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1390 1391 1392 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B", 1393 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1394 if (num_regions_removed > 0) { 1395 g1_policy()->record_new_heap_size(num_regions()); 1396 } else { 1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1398 } 1399 } 1400 1401 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1402 _verifier->verify_region_sets_optional(); 1403 1404 // We should only reach here at the end of a Full GC or during Remark which 1405 // means we should not not be holding to any GC alloc regions. The method 1406 // below will make sure of that and do any remaining clean up. 1407 _allocator->abandon_gc_alloc_regions(); 1408 1409 // Instead of tearing down / rebuilding the free lists here, we 1410 // could instead use the remove_all_pending() method on free_list to 1411 // remove only the ones that we need to remove. 1412 tear_down_region_sets(true /* free_list_only */); 1413 shrink_helper(shrink_bytes); 1414 rebuild_region_sets(true /* free_list_only */); 1415 1416 _hrm->verify_optional(); 1417 _verifier->verify_region_sets_optional(); 1418 } 1419 1420 class OldRegionSetChecker : public HeapRegionSetChecker { 1421 public: 1422 void check_mt_safety() { 1423 // Master Old Set MT safety protocol: 1424 // (a) If we're at a safepoint, operations on the master old set 1425 // should be invoked: 1426 // - by the VM thread (which will serialize them), or 1427 // - by the GC workers while holding the FreeList_lock, if we're 1428 // at a safepoint for an evacuation pause (this lock is taken 1429 // anyway when an GC alloc region is retired so that a new one 1430 // is allocated from the free list), or 1431 // - by the GC workers while holding the OldSets_lock, if we're at a 1432 // safepoint for a cleanup pause. 1433 // (b) If we're not at a safepoint, operations on the master old set 1434 // should be invoked while holding the Heap_lock. 1435 1436 if (SafepointSynchronize::is_at_safepoint()) { 1437 guarantee(Thread::current()->is_VM_thread() || 1438 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1439 "master old set MT safety protocol at a safepoint"); 1440 } else { 1441 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1442 } 1443 } 1444 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1445 const char* get_description() { return "Old Regions"; } 1446 }; 1447 1448 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1449 public: 1450 void check_mt_safety() { 1451 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1452 "May only change archive regions during initialization or safepoint."); 1453 } 1454 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1455 const char* get_description() { return "Archive Regions"; } 1456 }; 1457 1458 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1459 public: 1460 void check_mt_safety() { 1461 // Humongous Set MT safety protocol: 1462 // (a) If we're at a safepoint, operations on the master humongous 1463 // set should be invoked by either the VM thread (which will 1464 // serialize them) or by the GC workers while holding the 1465 // OldSets_lock. 1466 // (b) If we're not at a safepoint, operations on the master 1467 // humongous set should be invoked while holding the Heap_lock. 1468 1469 if (SafepointSynchronize::is_at_safepoint()) { 1470 guarantee(Thread::current()->is_VM_thread() || 1471 OldSets_lock->owned_by_self(), 1472 "master humongous set MT safety protocol at a safepoint"); 1473 } else { 1474 guarantee(Heap_lock->owned_by_self(), 1475 "master humongous set MT safety protocol outside a safepoint"); 1476 } 1477 } 1478 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1479 const char* get_description() { return "Humongous Regions"; } 1480 }; 1481 1482 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1483 CollectedHeap(), 1484 _young_gen_sampling_thread(NULL), 1485 _workers(NULL), 1486 _collector_policy(collector_policy), 1487 _card_table(NULL), 1488 _soft_ref_policy(), 1489 _old_set("Old Region Set", new OldRegionSetChecker()), 1490 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1491 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1492 _bot(NULL), 1493 _listener(), 1494 _hrm(NULL), 1495 _allocator(NULL), 1496 _verifier(NULL), 1497 _summary_bytes_used(0), 1498 _archive_allocator(NULL), 1499 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1500 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1501 _expand_heap_after_alloc_failure(true), 1502 _g1mm(NULL), 1503 _humongous_reclaim_candidates(), 1504 _has_humongous_reclaim_candidates(false), 1505 _hr_printer(), 1506 _collector_state(), 1507 _old_marking_cycles_started(0), 1508 _old_marking_cycles_completed(0), 1509 _eden(), 1510 _survivor(), 1511 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1512 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1513 _g1_policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)), 1514 _heap_sizing_policy(NULL), 1515 _collection_set(this, _g1_policy), 1516 _hot_card_cache(NULL), 1517 _g1_rem_set(NULL), 1518 _dirty_card_queue_set(false), 1519 _cm(NULL), 1520 _cm_thread(NULL), 1521 _cr(NULL), 1522 _task_queues(NULL), 1523 _evacuation_failed(false), 1524 _evacuation_failed_info_array(NULL), 1525 _preserved_marks_set(true /* in_c_heap */), 1526 #ifndef PRODUCT 1527 _evacuation_failure_alot_for_current_gc(false), 1528 _evacuation_failure_alot_gc_number(0), 1529 _evacuation_failure_alot_count(0), 1530 #endif 1531 _ref_processor_stw(NULL), 1532 _is_alive_closure_stw(this), 1533 _is_subject_to_discovery_stw(this), 1534 _ref_processor_cm(NULL), 1535 _is_alive_closure_cm(this), 1536 _is_subject_to_discovery_cm(this), 1537 _in_cset_fast_test() { 1538 1539 _verifier = new G1HeapVerifier(this); 1540 1541 _allocator = new G1Allocator(this); 1542 1543 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1544 1545 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1546 1547 // Override the default _filler_array_max_size so that no humongous filler 1548 // objects are created. 1549 _filler_array_max_size = _humongous_object_threshold_in_words; 1550 1551 uint n_queues = ParallelGCThreads; 1552 _task_queues = new RefToScanQueueSet(n_queues); 1553 1554 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1555 1556 for (uint i = 0; i < n_queues; i++) { 1557 RefToScanQueue* q = new RefToScanQueue(); 1558 q->initialize(); 1559 _task_queues->register_queue(i, q); 1560 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1561 } 1562 1563 // Initialize the G1EvacuationFailureALot counters and flags. 1564 NOT_PRODUCT(reset_evacuation_should_fail();) 1565 1566 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1567 } 1568 1569 static size_t actual_reserved_page_size(ReservedSpace rs) { 1570 size_t page_size = os::vm_page_size(); 1571 if (UseLargePages) { 1572 // There are two ways to manage large page memory. 1573 // 1. OS supports committing large page memory. 1574 // 2. OS doesn't support committing large page memory so ReservedSpace manages it. 1575 // And ReservedSpace calls it 'special'. If we failed to set 'special', 1576 // we reserved memory without large page. 1577 if (os::can_commit_large_page_memory() || rs.special()) { 1578 page_size = rs.alignment(); 1579 } 1580 } 1581 1582 return page_size; 1583 } 1584 1585 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1586 size_t size, 1587 size_t translation_factor) { 1588 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1589 // Allocate a new reserved space, preferring to use large pages. 1590 ReservedSpace rs(size, preferred_page_size); 1591 size_t page_size = actual_reserved_page_size(rs); 1592 G1RegionToSpaceMapper* result = 1593 G1RegionToSpaceMapper::create_mapper(rs, 1594 size, 1595 page_size, 1596 HeapRegion::GrainBytes, 1597 translation_factor, 1598 mtGC); 1599 1600 os::trace_page_sizes_for_requested_size(description, 1601 size, 1602 preferred_page_size, 1603 page_size, 1604 rs.base(), 1605 rs.size()); 1606 1607 return result; 1608 } 1609 1610 jint G1CollectedHeap::initialize_concurrent_refinement() { 1611 jint ecode = JNI_OK; 1612 _cr = G1ConcurrentRefine::create(&ecode); 1613 return ecode; 1614 } 1615 1616 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1617 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1618 if (_young_gen_sampling_thread->osthread() == NULL) { 1619 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1620 return JNI_ENOMEM; 1621 } 1622 return JNI_OK; 1623 } 1624 1625 jint G1CollectedHeap::initialize() { 1626 os::enable_vtime(); 1627 1628 // Necessary to satisfy locking discipline assertions. 1629 1630 MutexLocker x(Heap_lock); 1631 1632 // While there are no constraints in the GC code that HeapWordSize 1633 // be any particular value, there are multiple other areas in the 1634 // system which believe this to be true (e.g. oop->object_size in some 1635 // cases incorrectly returns the size in wordSize units rather than 1636 // HeapWordSize). 1637 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1638 1639 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1640 size_t max_byte_size = g1_collector_policy()->heap_reserved_size_bytes(); 1641 size_t heap_alignment = collector_policy()->heap_alignment(); 1642 1643 // Ensure that the sizes are properly aligned. 1644 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1645 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1646 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1647 1648 // Reserve the maximum. 1649 1650 // When compressed oops are enabled, the preferred heap base 1651 // is calculated by subtracting the requested size from the 1652 // 32Gb boundary and using the result as the base address for 1653 // heap reservation. If the requested size is not aligned to 1654 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1655 // into the ReservedHeapSpace constructor) then the actual 1656 // base of the reserved heap may end up differing from the 1657 // address that was requested (i.e. the preferred heap base). 1658 // If this happens then we could end up using a non-optimal 1659 // compressed oops mode. 1660 1661 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1662 heap_alignment); 1663 1664 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1665 1666 // Create the barrier set for the entire reserved region. 1667 G1CardTable* ct = new G1CardTable(reserved_region()); 1668 ct->initialize(); 1669 G1BarrierSet* bs = new G1BarrierSet(ct); 1670 bs->initialize(); 1671 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1672 BarrierSet::set_barrier_set(bs); 1673 _card_table = ct; 1674 1675 G1BarrierSet::satb_mark_queue_set().initialize(this, 1676 SATB_Q_CBL_mon, 1677 &bs->satb_mark_queue_buffer_allocator(), 1678 G1SATBProcessCompletedThreshold, 1679 G1SATBBufferEnqueueingThresholdPercent, 1680 Shared_SATB_Q_lock); 1681 1682 // process_completed_buffers_threshold and max_completed_buffers are updated 1683 // later, based on the concurrent refinement object. 1684 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1685 &bs->dirty_card_queue_buffer_allocator(), 1686 Shared_DirtyCardQ_lock, 1687 true); // init_free_ids 1688 1689 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1690 &bs->dirty_card_queue_buffer_allocator(), 1691 Shared_DirtyCardQ_lock); 1692 1693 // Create the hot card cache. 1694 _hot_card_cache = new G1HotCardCache(this); 1695 1696 // Carve out the G1 part of the heap. 1697 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1698 size_t page_size = actual_reserved_page_size(heap_rs); 1699 G1RegionToSpaceMapper* heap_storage = 1700 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1701 g1_rs.size(), 1702 page_size, 1703 HeapRegion::GrainBytes, 1704 1, 1705 mtJavaHeap); 1706 if(heap_storage == NULL) { 1707 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1708 return JNI_ERR; 1709 } 1710 1711 os::trace_page_sizes("Heap", 1712 collector_policy()->min_heap_byte_size(), 1713 max_byte_size, 1714 page_size, 1715 heap_rs.base(), 1716 heap_rs.size()); 1717 heap_storage->set_mapping_changed_listener(&_listener); 1718 1719 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1720 G1RegionToSpaceMapper* bot_storage = 1721 create_aux_memory_mapper("Block Offset Table", 1722 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1723 G1BlockOffsetTable::heap_map_factor()); 1724 1725 G1RegionToSpaceMapper* cardtable_storage = 1726 create_aux_memory_mapper("Card Table", 1727 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1728 G1CardTable::heap_map_factor()); 1729 1730 G1RegionToSpaceMapper* card_counts_storage = 1731 create_aux_memory_mapper("Card Counts Table", 1732 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1733 G1CardCounts::heap_map_factor()); 1734 1735 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1736 G1RegionToSpaceMapper* prev_bitmap_storage = 1737 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1738 G1RegionToSpaceMapper* next_bitmap_storage = 1739 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1740 1741 _hrm = HeapRegionManager::create_manager(this, g1_collector_policy()); 1742 1743 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1744 _card_table->initialize(cardtable_storage); 1745 // Do later initialization work for concurrent refinement. 1746 _hot_card_cache->initialize(card_counts_storage); 1747 1748 // 6843694 - ensure that the maximum region index can fit 1749 // in the remembered set structures. 1750 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1751 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1752 1753 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1754 // start within the first card. 1755 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1756 // Also create a G1 rem set. 1757 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1758 _g1_rem_set->initialize(max_reserved_capacity(), max_regions()); 1759 1760 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1761 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1762 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1763 "too many cards per region"); 1764 1765 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1766 1767 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1768 1769 { 1770 HeapWord* start = _hrm->reserved().start(); 1771 HeapWord* end = _hrm->reserved().end(); 1772 size_t granularity = HeapRegion::GrainBytes; 1773 1774 _in_cset_fast_test.initialize(start, end, granularity); 1775 _humongous_reclaim_candidates.initialize(start, end, granularity); 1776 } 1777 1778 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1779 true /* are_GC_task_threads */, 1780 false /* are_ConcurrentGC_threads */); 1781 if (_workers == NULL) { 1782 return JNI_ENOMEM; 1783 } 1784 _workers->initialize_workers(); 1785 1786 // Create the G1ConcurrentMark data structure and thread. 1787 // (Must do this late, so that "max_regions" is defined.) 1788 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1789 if (_cm == NULL || !_cm->completed_initialization()) { 1790 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1791 return JNI_ENOMEM; 1792 } 1793 _cm_thread = _cm->cm_thread(); 1794 1795 // Now expand into the initial heap size. 1796 if (!expand(init_byte_size, _workers)) { 1797 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1798 return JNI_ENOMEM; 1799 } 1800 1801 // Perform any initialization actions delegated to the policy. 1802 g1_policy()->init(this, &_collection_set); 1803 1804 jint ecode = initialize_concurrent_refinement(); 1805 if (ecode != JNI_OK) { 1806 return ecode; 1807 } 1808 1809 ecode = initialize_young_gen_sampling_thread(); 1810 if (ecode != JNI_OK) { 1811 return ecode; 1812 } 1813 1814 { 1815 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1816 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone()); 1817 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone()); 1818 } 1819 1820 // Here we allocate the dummy HeapRegion that is required by the 1821 // G1AllocRegion class. 1822 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1823 1824 // We'll re-use the same region whether the alloc region will 1825 // require BOT updates or not and, if it doesn't, then a non-young 1826 // region will complain that it cannot support allocations without 1827 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1828 dummy_region->set_eden(); 1829 // Make sure it's full. 1830 dummy_region->set_top(dummy_region->end()); 1831 G1AllocRegion::setup(this, dummy_region); 1832 1833 _allocator->init_mutator_alloc_region(); 1834 1835 // Do create of the monitoring and management support so that 1836 // values in the heap have been properly initialized. 1837 _g1mm = new G1MonitoringSupport(this); 1838 1839 G1StringDedup::initialize(); 1840 1841 _preserved_marks_set.init(ParallelGCThreads); 1842 1843 _collection_set.initialize(max_regions()); 1844 1845 return JNI_OK; 1846 } 1847 1848 void G1CollectedHeap::stop() { 1849 // Stop all concurrent threads. We do this to make sure these threads 1850 // do not continue to execute and access resources (e.g. logging) 1851 // that are destroyed during shutdown. 1852 _cr->stop(); 1853 _young_gen_sampling_thread->stop(); 1854 _cm_thread->stop(); 1855 if (G1StringDedup::is_enabled()) { 1856 G1StringDedup::stop(); 1857 } 1858 } 1859 1860 void G1CollectedHeap::safepoint_synchronize_begin() { 1861 SuspendibleThreadSet::synchronize(); 1862 } 1863 1864 void G1CollectedHeap::safepoint_synchronize_end() { 1865 SuspendibleThreadSet::desynchronize(); 1866 } 1867 1868 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1869 return HeapRegion::max_region_size(); 1870 } 1871 1872 void G1CollectedHeap::post_initialize() { 1873 CollectedHeap::post_initialize(); 1874 ref_processing_init(); 1875 } 1876 1877 void G1CollectedHeap::ref_processing_init() { 1878 // Reference processing in G1 currently works as follows: 1879 // 1880 // * There are two reference processor instances. One is 1881 // used to record and process discovered references 1882 // during concurrent marking; the other is used to 1883 // record and process references during STW pauses 1884 // (both full and incremental). 1885 // * Both ref processors need to 'span' the entire heap as 1886 // the regions in the collection set may be dotted around. 1887 // 1888 // * For the concurrent marking ref processor: 1889 // * Reference discovery is enabled at initial marking. 1890 // * Reference discovery is disabled and the discovered 1891 // references processed etc during remarking. 1892 // * Reference discovery is MT (see below). 1893 // * Reference discovery requires a barrier (see below). 1894 // * Reference processing may or may not be MT 1895 // (depending on the value of ParallelRefProcEnabled 1896 // and ParallelGCThreads). 1897 // * A full GC disables reference discovery by the CM 1898 // ref processor and abandons any entries on it's 1899 // discovered lists. 1900 // 1901 // * For the STW processor: 1902 // * Non MT discovery is enabled at the start of a full GC. 1903 // * Processing and enqueueing during a full GC is non-MT. 1904 // * During a full GC, references are processed after marking. 1905 // 1906 // * Discovery (may or may not be MT) is enabled at the start 1907 // of an incremental evacuation pause. 1908 // * References are processed near the end of a STW evacuation pause. 1909 // * For both types of GC: 1910 // * Discovery is atomic - i.e. not concurrent. 1911 // * Reference discovery will not need a barrier. 1912 1913 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1914 1915 // Concurrent Mark ref processor 1916 _ref_processor_cm = 1917 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1918 mt_processing, // mt processing 1919 ParallelGCThreads, // degree of mt processing 1920 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1921 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1922 false, // Reference discovery is not atomic 1923 &_is_alive_closure_cm, // is alive closure 1924 true); // allow changes to number of processing threads 1925 1926 // STW ref processor 1927 _ref_processor_stw = 1928 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1929 mt_processing, // mt processing 1930 ParallelGCThreads, // degree of mt processing 1931 (ParallelGCThreads > 1), // mt discovery 1932 ParallelGCThreads, // degree of mt discovery 1933 true, // Reference discovery is atomic 1934 &_is_alive_closure_stw, // is alive closure 1935 true); // allow changes to number of processing threads 1936 } 1937 1938 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1939 return _collector_policy; 1940 } 1941 1942 G1CollectorPolicy* G1CollectedHeap::g1_collector_policy() const { 1943 return _collector_policy; 1944 } 1945 1946 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1947 return &_soft_ref_policy; 1948 } 1949 1950 size_t G1CollectedHeap::capacity() const { 1951 return _hrm->length() * HeapRegion::GrainBytes; 1952 } 1953 1954 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1955 return _hrm->total_free_bytes(); 1956 } 1957 1958 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1959 _hot_card_cache->drain(cl, worker_i); 1960 } 1961 1962 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) { 1963 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1964 size_t n_completed_buffers = 0; 1965 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1966 n_completed_buffers++; 1967 } 1968 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!"); 1969 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1970 } 1971 1972 // Computes the sum of the storage used by the various regions. 1973 size_t G1CollectedHeap::used() const { 1974 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1975 if (_archive_allocator != NULL) { 1976 result += _archive_allocator->used(); 1977 } 1978 return result; 1979 } 1980 1981 size_t G1CollectedHeap::used_unlocked() const { 1982 return _summary_bytes_used; 1983 } 1984 1985 class SumUsedClosure: public HeapRegionClosure { 1986 size_t _used; 1987 public: 1988 SumUsedClosure() : _used(0) {} 1989 bool do_heap_region(HeapRegion* r) { 1990 _used += r->used(); 1991 return false; 1992 } 1993 size_t result() { return _used; } 1994 }; 1995 1996 size_t G1CollectedHeap::recalculate_used() const { 1997 SumUsedClosure blk; 1998 heap_region_iterate(&blk); 1999 return blk.result(); 2000 } 2001 2002 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 2003 switch (cause) { 2004 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 2005 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 2006 case GCCause::_wb_conc_mark: return true; 2007 default : return false; 2008 } 2009 } 2010 2011 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2012 switch (cause) { 2013 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2014 case GCCause::_g1_humongous_allocation: return true; 2015 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent; 2016 default: return is_user_requested_concurrent_full_gc(cause); 2017 } 2018 } 2019 2020 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) { 2021 if(g1_policy()->force_upgrade_to_full()) { 2022 return true; 2023 } else if (should_do_concurrent_full_gc(_gc_cause)) { 2024 return false; 2025 } else if (has_regions_left_for_allocation()) { 2026 return false; 2027 } else { 2028 return true; 2029 } 2030 } 2031 2032 #ifndef PRODUCT 2033 void G1CollectedHeap::allocate_dummy_regions() { 2034 // Let's fill up most of the region 2035 size_t word_size = HeapRegion::GrainWords - 1024; 2036 // And as a result the region we'll allocate will be humongous. 2037 guarantee(is_humongous(word_size), "sanity"); 2038 2039 // _filler_array_max_size is set to humongous object threshold 2040 // but temporarily change it to use CollectedHeap::fill_with_object(). 2041 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2042 2043 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2044 // Let's use the existing mechanism for the allocation 2045 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2046 if (dummy_obj != NULL) { 2047 MemRegion mr(dummy_obj, word_size); 2048 CollectedHeap::fill_with_object(mr); 2049 } else { 2050 // If we can't allocate once, we probably cannot allocate 2051 // again. Let's get out of the loop. 2052 break; 2053 } 2054 } 2055 } 2056 #endif // !PRODUCT 2057 2058 void G1CollectedHeap::increment_old_marking_cycles_started() { 2059 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2060 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2061 "Wrong marking cycle count (started: %d, completed: %d)", 2062 _old_marking_cycles_started, _old_marking_cycles_completed); 2063 2064 _old_marking_cycles_started++; 2065 } 2066 2067 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2068 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2069 2070 // We assume that if concurrent == true, then the caller is a 2071 // concurrent thread that was joined the Suspendible Thread 2072 // Set. If there's ever a cheap way to check this, we should add an 2073 // assert here. 2074 2075 // Given that this method is called at the end of a Full GC or of a 2076 // concurrent cycle, and those can be nested (i.e., a Full GC can 2077 // interrupt a concurrent cycle), the number of full collections 2078 // completed should be either one (in the case where there was no 2079 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2080 // behind the number of full collections started. 2081 2082 // This is the case for the inner caller, i.e. a Full GC. 2083 assert(concurrent || 2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2085 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2086 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2087 "is inconsistent with _old_marking_cycles_completed = %u", 2088 _old_marking_cycles_started, _old_marking_cycles_completed); 2089 2090 // This is the case for the outer caller, i.e. the concurrent cycle. 2091 assert(!concurrent || 2092 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2093 "for outer caller (concurrent cycle): " 2094 "_old_marking_cycles_started = %u " 2095 "is inconsistent with _old_marking_cycles_completed = %u", 2096 _old_marking_cycles_started, _old_marking_cycles_completed); 2097 2098 _old_marking_cycles_completed += 1; 2099 2100 // We need to clear the "in_progress" flag in the CM thread before 2101 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2102 // is set) so that if a waiter requests another System.gc() it doesn't 2103 // incorrectly see that a marking cycle is still in progress. 2104 if (concurrent) { 2105 _cm_thread->set_idle(); 2106 } 2107 2108 // This notify_all() will ensure that a thread that called 2109 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2110 // and it's waiting for a full GC to finish will be woken up. It is 2111 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2112 FullGCCount_lock->notify_all(); 2113 } 2114 2115 void G1CollectedHeap::collect(GCCause::Cause cause) { 2116 assert_heap_not_locked(); 2117 2118 uint gc_count_before; 2119 uint old_marking_count_before; 2120 uint full_gc_count_before; 2121 bool retry_gc; 2122 2123 do { 2124 retry_gc = false; 2125 2126 { 2127 MutexLocker ml(Heap_lock); 2128 2129 // Read the GC count while holding the Heap_lock 2130 gc_count_before = total_collections(); 2131 full_gc_count_before = total_full_collections(); 2132 old_marking_count_before = _old_marking_cycles_started; 2133 } 2134 2135 if (should_do_concurrent_full_gc(cause)) { 2136 // Schedule an initial-mark evacuation pause that will start a 2137 // concurrent cycle. We're setting word_size to 0 which means that 2138 // we are not requesting a post-GC allocation. 2139 VM_G1CollectForAllocation op(0, /* word_size */ 2140 gc_count_before, 2141 cause, 2142 true, /* should_initiate_conc_mark */ 2143 g1_policy()->max_pause_time_ms()); 2144 VMThread::execute(&op); 2145 if (!op.pause_succeeded()) { 2146 if (old_marking_count_before == _old_marking_cycles_started) { 2147 retry_gc = op.should_retry_gc(); 2148 } else { 2149 // A Full GC happened while we were trying to schedule the 2150 // initial-mark GC. No point in starting a new cycle given 2151 // that the whole heap was collected anyway. 2152 } 2153 2154 if (retry_gc) { 2155 if (GCLocker::is_active_and_needs_gc()) { 2156 GCLocker::stall_until_clear(); 2157 } 2158 } 2159 } 2160 } else { 2161 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2162 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2163 2164 // Schedule a standard evacuation pause. We're setting word_size 2165 // to 0 which means that we are not requesting a post-GC allocation. 2166 VM_G1CollectForAllocation op(0, /* word_size */ 2167 gc_count_before, 2168 cause, 2169 false, /* should_initiate_conc_mark */ 2170 g1_policy()->max_pause_time_ms()); 2171 VMThread::execute(&op); 2172 } else { 2173 // Schedule a Full GC. 2174 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2175 VMThread::execute(&op); 2176 } 2177 } 2178 } while (retry_gc); 2179 } 2180 2181 bool G1CollectedHeap::is_in(const void* p) const { 2182 if (_hrm->reserved().contains(p)) { 2183 // Given that we know that p is in the reserved space, 2184 // heap_region_containing() should successfully 2185 // return the containing region. 2186 HeapRegion* hr = heap_region_containing(p); 2187 return hr->is_in(p); 2188 } else { 2189 return false; 2190 } 2191 } 2192 2193 #ifdef ASSERT 2194 bool G1CollectedHeap::is_in_exact(const void* p) const { 2195 bool contains = reserved_region().contains(p); 2196 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2197 if (contains && available) { 2198 return true; 2199 } else { 2200 return false; 2201 } 2202 } 2203 #endif 2204 2205 // Iteration functions. 2206 2207 // Iterates an ObjectClosure over all objects within a HeapRegion. 2208 2209 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2210 ObjectClosure* _cl; 2211 public: 2212 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2213 bool do_heap_region(HeapRegion* r) { 2214 if (!r->is_continues_humongous()) { 2215 r->object_iterate(_cl); 2216 } 2217 return false; 2218 } 2219 }; 2220 2221 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2222 IterateObjectClosureRegionClosure blk(cl); 2223 heap_region_iterate(&blk); 2224 } 2225 2226 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2227 _hrm->iterate(cl); 2228 } 2229 2230 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2231 HeapRegionClaimer *hrclaimer, 2232 uint worker_id) const { 2233 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2234 } 2235 2236 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2237 HeapRegionClaimer *hrclaimer) const { 2238 _hrm->par_iterate(cl, hrclaimer, 0); 2239 } 2240 2241 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2242 _collection_set.iterate(cl); 2243 } 2244 2245 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2246 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2247 } 2248 2249 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2250 HeapRegion* hr = heap_region_containing(addr); 2251 return hr->block_start(addr); 2252 } 2253 2254 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2255 HeapRegion* hr = heap_region_containing(addr); 2256 return hr->block_is_obj(addr); 2257 } 2258 2259 bool G1CollectedHeap::supports_tlab_allocation() const { 2260 return true; 2261 } 2262 2263 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2264 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2265 } 2266 2267 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2268 return _eden.length() * HeapRegion::GrainBytes; 2269 } 2270 2271 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2272 // must be equal to the humongous object limit. 2273 size_t G1CollectedHeap::max_tlab_size() const { 2274 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2275 } 2276 2277 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2278 return _allocator->unsafe_max_tlab_alloc(); 2279 } 2280 2281 size_t G1CollectedHeap::max_capacity() const { 2282 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2283 } 2284 2285 size_t G1CollectedHeap::max_reserved_capacity() const { 2286 return _hrm->max_length() * HeapRegion::GrainBytes; 2287 } 2288 2289 jlong G1CollectedHeap::millis_since_last_gc() { 2290 // See the notes in GenCollectedHeap::millis_since_last_gc() 2291 // for more information about the implementation. 2292 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2293 _g1_policy->collection_pause_end_millis(); 2294 if (ret_val < 0) { 2295 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2296 ". returning zero instead.", ret_val); 2297 return 0; 2298 } 2299 return ret_val; 2300 } 2301 2302 void G1CollectedHeap::deduplicate_string(oop str) { 2303 assert(java_lang_String::is_instance(str), "invariant"); 2304 2305 if (G1StringDedup::is_enabled()) { 2306 G1StringDedup::deduplicate(str); 2307 } 2308 } 2309 2310 void G1CollectedHeap::prepare_for_verify() { 2311 _verifier->prepare_for_verify(); 2312 } 2313 2314 void G1CollectedHeap::verify(VerifyOption vo) { 2315 _verifier->verify(vo); 2316 } 2317 2318 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2319 return true; 2320 } 2321 2322 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2323 return _cm_thread->request_concurrent_phase(phase); 2324 } 2325 2326 class PrintRegionClosure: public HeapRegionClosure { 2327 outputStream* _st; 2328 public: 2329 PrintRegionClosure(outputStream* st) : _st(st) {} 2330 bool do_heap_region(HeapRegion* r) { 2331 r->print_on(_st); 2332 return false; 2333 } 2334 }; 2335 2336 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2337 const HeapRegion* hr, 2338 const VerifyOption vo) const { 2339 switch (vo) { 2340 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2341 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2342 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2343 default: ShouldNotReachHere(); 2344 } 2345 return false; // keep some compilers happy 2346 } 2347 2348 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2349 const VerifyOption vo) const { 2350 switch (vo) { 2351 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2352 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2353 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2354 default: ShouldNotReachHere(); 2355 } 2356 return false; // keep some compilers happy 2357 } 2358 2359 void G1CollectedHeap::print_heap_regions() const { 2360 LogTarget(Trace, gc, heap, region) lt; 2361 if (lt.is_enabled()) { 2362 LogStream ls(lt); 2363 print_regions_on(&ls); 2364 } 2365 } 2366 2367 void G1CollectedHeap::print_on(outputStream* st) const { 2368 st->print(" %-20s", "garbage-first heap"); 2369 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2370 capacity()/K, used_unlocked()/K); 2371 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2372 p2i(_hrm->reserved().start()), 2373 p2i(_hrm->reserved().end())); 2374 st->cr(); 2375 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2376 uint young_regions = young_regions_count(); 2377 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2378 (size_t) young_regions * HeapRegion::GrainBytes / K); 2379 uint survivor_regions = survivor_regions_count(); 2380 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2381 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2382 st->cr(); 2383 MetaspaceUtils::print_on(st); 2384 } 2385 2386 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2387 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2388 "HS=humongous(starts), HC=humongous(continues), " 2389 "CS=collection set, F=free, A=archive, " 2390 "TAMS=top-at-mark-start (previous, next)"); 2391 PrintRegionClosure blk(st); 2392 heap_region_iterate(&blk); 2393 } 2394 2395 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2396 print_on(st); 2397 2398 // Print the per-region information. 2399 print_regions_on(st); 2400 } 2401 2402 void G1CollectedHeap::print_on_error(outputStream* st) const { 2403 this->CollectedHeap::print_on_error(st); 2404 2405 if (_cm != NULL) { 2406 st->cr(); 2407 _cm->print_on_error(st); 2408 } 2409 } 2410 2411 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2412 workers()->print_worker_threads_on(st); 2413 _cm_thread->print_on(st); 2414 st->cr(); 2415 _cm->print_worker_threads_on(st); 2416 _cr->print_threads_on(st); 2417 _young_gen_sampling_thread->print_on(st); 2418 if (G1StringDedup::is_enabled()) { 2419 G1StringDedup::print_worker_threads_on(st); 2420 } 2421 } 2422 2423 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2424 workers()->threads_do(tc); 2425 tc->do_thread(_cm_thread); 2426 _cm->threads_do(tc); 2427 _cr->threads_do(tc); 2428 tc->do_thread(_young_gen_sampling_thread); 2429 if (G1StringDedup::is_enabled()) { 2430 G1StringDedup::threads_do(tc); 2431 } 2432 } 2433 2434 void G1CollectedHeap::print_tracing_info() const { 2435 g1_rem_set()->print_summary_info(); 2436 concurrent_mark()->print_summary_info(); 2437 } 2438 2439 #ifndef PRODUCT 2440 // Helpful for debugging RSet issues. 2441 2442 class PrintRSetsClosure : public HeapRegionClosure { 2443 private: 2444 const char* _msg; 2445 size_t _occupied_sum; 2446 2447 public: 2448 bool do_heap_region(HeapRegion* r) { 2449 HeapRegionRemSet* hrrs = r->rem_set(); 2450 size_t occupied = hrrs->occupied(); 2451 _occupied_sum += occupied; 2452 2453 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2454 if (occupied == 0) { 2455 tty->print_cr(" RSet is empty"); 2456 } else { 2457 hrrs->print(); 2458 } 2459 tty->print_cr("----------"); 2460 return false; 2461 } 2462 2463 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2464 tty->cr(); 2465 tty->print_cr("========================================"); 2466 tty->print_cr("%s", msg); 2467 tty->cr(); 2468 } 2469 2470 ~PrintRSetsClosure() { 2471 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2472 tty->print_cr("========================================"); 2473 tty->cr(); 2474 } 2475 }; 2476 2477 void G1CollectedHeap::print_cset_rsets() { 2478 PrintRSetsClosure cl("Printing CSet RSets"); 2479 collection_set_iterate(&cl); 2480 } 2481 2482 void G1CollectedHeap::print_all_rsets() { 2483 PrintRSetsClosure cl("Printing All RSets");; 2484 heap_region_iterate(&cl); 2485 } 2486 #endif // PRODUCT 2487 2488 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2489 2490 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2491 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2492 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2493 2494 size_t eden_capacity_bytes = 2495 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2496 2497 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2498 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2499 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2500 } 2501 2502 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2503 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2504 stats->unused(), stats->used(), stats->region_end_waste(), 2505 stats->regions_filled(), stats->direct_allocated(), 2506 stats->failure_used(), stats->failure_waste()); 2507 } 2508 2509 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2510 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2511 gc_tracer->report_gc_heap_summary(when, heap_summary); 2512 2513 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2514 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2515 } 2516 2517 G1CollectedHeap* G1CollectedHeap::heap() { 2518 CollectedHeap* heap = Universe::heap(); 2519 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2520 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2521 return (G1CollectedHeap*)heap; 2522 } 2523 2524 void G1CollectedHeap::gc_prologue(bool full) { 2525 // always_do_update_barrier = false; 2526 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2527 2528 // This summary needs to be printed before incrementing total collections. 2529 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2530 2531 // Update common counters. 2532 increment_total_collections(full /* full gc */); 2533 if (full) { 2534 increment_old_marking_cycles_started(); 2535 } 2536 2537 // Fill TLAB's and such 2538 double start = os::elapsedTime(); 2539 ensure_parsability(true); 2540 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2541 } 2542 2543 void G1CollectedHeap::gc_epilogue(bool full) { 2544 // Update common counters. 2545 if (full) { 2546 // Update the number of full collections that have been completed. 2547 increment_old_marking_cycles_completed(false /* concurrent */); 2548 } 2549 2550 // We are at the end of the GC. Total collections has already been increased. 2551 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2552 2553 // FIXME: what is this about? 2554 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2555 // is set. 2556 #if COMPILER2_OR_JVMCI 2557 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2558 #endif 2559 // always_do_update_barrier = true; 2560 2561 double start = os::elapsedTime(); 2562 resize_all_tlabs(); 2563 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2564 2565 MemoryService::track_memory_usage(); 2566 // We have just completed a GC. Update the soft reference 2567 // policy with the new heap occupancy 2568 Universe::update_heap_info_at_gc(); 2569 } 2570 2571 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2572 uint gc_count_before, 2573 bool* succeeded, 2574 GCCause::Cause gc_cause) { 2575 assert_heap_not_locked_and_not_at_safepoint(); 2576 VM_G1CollectForAllocation op(word_size, 2577 gc_count_before, 2578 gc_cause, 2579 false, /* should_initiate_conc_mark */ 2580 g1_policy()->max_pause_time_ms()); 2581 VMThread::execute(&op); 2582 2583 HeapWord* result = op.result(); 2584 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2585 assert(result == NULL || ret_succeeded, 2586 "the result should be NULL if the VM did not succeed"); 2587 *succeeded = ret_succeeded; 2588 2589 assert_heap_not_locked(); 2590 return result; 2591 } 2592 2593 void G1CollectedHeap::do_concurrent_mark() { 2594 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2595 if (!_cm_thread->in_progress()) { 2596 _cm_thread->set_started(); 2597 CGC_lock->notify(); 2598 } 2599 } 2600 2601 size_t G1CollectedHeap::pending_card_num() { 2602 size_t extra_cards = 0; 2603 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2604 G1DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2605 extra_cards += dcq.size(); 2606 } 2607 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2608 size_t buffer_size = dcqs.buffer_size(); 2609 size_t buffer_num = dcqs.completed_buffers_num(); 2610 2611 return buffer_size * buffer_num + extra_cards; 2612 } 2613 2614 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2615 // We don't nominate objects with many remembered set entries, on 2616 // the assumption that such objects are likely still live. 2617 HeapRegionRemSet* rem_set = r->rem_set(); 2618 2619 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2620 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2621 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2622 } 2623 2624 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2625 private: 2626 size_t _total_humongous; 2627 size_t _candidate_humongous; 2628 2629 G1DirtyCardQueue _dcq; 2630 2631 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2632 assert(region->is_starts_humongous(), "Must start a humongous object"); 2633 2634 oop obj = oop(region->bottom()); 2635 2636 // Dead objects cannot be eager reclaim candidates. Due to class 2637 // unloading it is unsafe to query their classes so we return early. 2638 if (g1h->is_obj_dead(obj, region)) { 2639 return false; 2640 } 2641 2642 // If we do not have a complete remembered set for the region, then we can 2643 // not be sure that we have all references to it. 2644 if (!region->rem_set()->is_complete()) { 2645 return false; 2646 } 2647 // Candidate selection must satisfy the following constraints 2648 // while concurrent marking is in progress: 2649 // 2650 // * In order to maintain SATB invariants, an object must not be 2651 // reclaimed if it was allocated before the start of marking and 2652 // has not had its references scanned. Such an object must have 2653 // its references (including type metadata) scanned to ensure no 2654 // live objects are missed by the marking process. Objects 2655 // allocated after the start of concurrent marking don't need to 2656 // be scanned. 2657 // 2658 // * An object must not be reclaimed if it is on the concurrent 2659 // mark stack. Objects allocated after the start of concurrent 2660 // marking are never pushed on the mark stack. 2661 // 2662 // Nominating only objects allocated after the start of concurrent 2663 // marking is sufficient to meet both constraints. This may miss 2664 // some objects that satisfy the constraints, but the marking data 2665 // structures don't support efficiently performing the needed 2666 // additional tests or scrubbing of the mark stack. 2667 // 2668 // However, we presently only nominate is_typeArray() objects. 2669 // A humongous object containing references induces remembered 2670 // set entries on other regions. In order to reclaim such an 2671 // object, those remembered sets would need to be cleaned up. 2672 // 2673 // We also treat is_typeArray() objects specially, allowing them 2674 // to be reclaimed even if allocated before the start of 2675 // concurrent mark. For this we rely on mark stack insertion to 2676 // exclude is_typeArray() objects, preventing reclaiming an object 2677 // that is in the mark stack. We also rely on the metadata for 2678 // such objects to be built-in and so ensured to be kept live. 2679 // Frequent allocation and drop of large binary blobs is an 2680 // important use case for eager reclaim, and this special handling 2681 // may reduce needed headroom. 2682 2683 return obj->is_typeArray() && 2684 g1h->is_potential_eager_reclaim_candidate(region); 2685 } 2686 2687 public: 2688 RegisterHumongousWithInCSetFastTestClosure() 2689 : _total_humongous(0), 2690 _candidate_humongous(0), 2691 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2692 } 2693 2694 virtual bool do_heap_region(HeapRegion* r) { 2695 if (!r->is_starts_humongous()) { 2696 return false; 2697 } 2698 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2699 2700 bool is_candidate = humongous_region_is_candidate(g1h, r); 2701 uint rindex = r->hrm_index(); 2702 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2703 if (is_candidate) { 2704 _candidate_humongous++; 2705 g1h->register_humongous_region_with_cset(rindex); 2706 // Is_candidate already filters out humongous object with large remembered sets. 2707 // If we have a humongous object with a few remembered sets, we simply flush these 2708 // remembered set entries into the DCQS. That will result in automatic 2709 // re-evaluation of their remembered set entries during the following evacuation 2710 // phase. 2711 if (!r->rem_set()->is_empty()) { 2712 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2713 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2714 G1CardTable* ct = g1h->card_table(); 2715 HeapRegionRemSetIterator hrrs(r->rem_set()); 2716 size_t card_index; 2717 while (hrrs.has_next(card_index)) { 2718 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2719 // The remembered set might contain references to already freed 2720 // regions. Filter out such entries to avoid failing card table 2721 // verification. 2722 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2723 if (*card_ptr != G1CardTable::dirty_card_val()) { 2724 *card_ptr = G1CardTable::dirty_card_val(); 2725 _dcq.enqueue(card_ptr); 2726 } 2727 } 2728 } 2729 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2730 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2731 hrrs.n_yielded(), r->rem_set()->occupied()); 2732 // We should only clear the card based remembered set here as we will not 2733 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2734 // (and probably never) we do not enter this path if there are other kind of 2735 // remembered sets for this region. 2736 r->rem_set()->clear_locked(true /* only_cardset */); 2737 // Clear_locked() above sets the state to Empty. However we want to continue 2738 // collecting remembered set entries for humongous regions that were not 2739 // reclaimed. 2740 r->rem_set()->set_state_complete(); 2741 } 2742 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2743 } 2744 _total_humongous++; 2745 2746 return false; 2747 } 2748 2749 size_t total_humongous() const { return _total_humongous; } 2750 size_t candidate_humongous() const { return _candidate_humongous; } 2751 2752 void flush_rem_set_entries() { _dcq.flush(); } 2753 }; 2754 2755 void G1CollectedHeap::register_humongous_regions_with_cset() { 2756 if (!G1EagerReclaimHumongousObjects) { 2757 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2758 return; 2759 } 2760 double time = os::elapsed_counter(); 2761 2762 // Collect reclaim candidate information and register candidates with cset. 2763 RegisterHumongousWithInCSetFastTestClosure cl; 2764 heap_region_iterate(&cl); 2765 2766 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2767 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2768 cl.total_humongous(), 2769 cl.candidate_humongous()); 2770 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2771 2772 // Finally flush all remembered set entries to re-check into the global DCQS. 2773 cl.flush_rem_set_entries(); 2774 } 2775 2776 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2777 public: 2778 bool do_heap_region(HeapRegion* hr) { 2779 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2780 hr->verify_rem_set(); 2781 } 2782 return false; 2783 } 2784 }; 2785 2786 uint G1CollectedHeap::num_task_queues() const { 2787 return _task_queues->size(); 2788 } 2789 2790 #if TASKQUEUE_STATS 2791 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2792 st->print_raw_cr("GC Task Stats"); 2793 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2794 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2795 } 2796 2797 void G1CollectedHeap::print_taskqueue_stats() const { 2798 if (!log_is_enabled(Trace, gc, task, stats)) { 2799 return; 2800 } 2801 Log(gc, task, stats) log; 2802 ResourceMark rm; 2803 LogStream ls(log.trace()); 2804 outputStream* st = &ls; 2805 2806 print_taskqueue_stats_hdr(st); 2807 2808 TaskQueueStats totals; 2809 const uint n = num_task_queues(); 2810 for (uint i = 0; i < n; ++i) { 2811 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2812 totals += task_queue(i)->stats; 2813 } 2814 st->print_raw("tot "); totals.print(st); st->cr(); 2815 2816 DEBUG_ONLY(totals.verify()); 2817 } 2818 2819 void G1CollectedHeap::reset_taskqueue_stats() { 2820 const uint n = num_task_queues(); 2821 for (uint i = 0; i < n; ++i) { 2822 task_queue(i)->stats.reset(); 2823 } 2824 } 2825 #endif // TASKQUEUE_STATS 2826 2827 void G1CollectedHeap::wait_for_root_region_scanning() { 2828 double scan_wait_start = os::elapsedTime(); 2829 // We have to wait until the CM threads finish scanning the 2830 // root regions as it's the only way to ensure that all the 2831 // objects on them have been correctly scanned before we start 2832 // moving them during the GC. 2833 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2834 double wait_time_ms = 0.0; 2835 if (waited) { 2836 double scan_wait_end = os::elapsedTime(); 2837 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2838 } 2839 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2840 } 2841 2842 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2843 private: 2844 G1HRPrinter* _hr_printer; 2845 public: 2846 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2847 2848 virtual bool do_heap_region(HeapRegion* r) { 2849 _hr_printer->cset(r); 2850 return false; 2851 } 2852 }; 2853 2854 void G1CollectedHeap::start_new_collection_set() { 2855 collection_set()->start_incremental_building(); 2856 2857 clear_cset_fast_test(); 2858 2859 guarantee(_eden.length() == 0, "eden should have been cleared"); 2860 g1_policy()->transfer_survivors_to_cset(survivor()); 2861 } 2862 2863 bool 2864 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2865 assert_at_safepoint_on_vm_thread(); 2866 guarantee(!is_gc_active(), "collection is not reentrant"); 2867 2868 if (GCLocker::check_active_before_gc()) { 2869 return false; 2870 } 2871 2872 _gc_timer_stw->register_gc_start(); 2873 2874 GCIdMark gc_id_mark; 2875 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2876 2877 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2878 ResourceMark rm; 2879 2880 g1_policy()->note_gc_start(); 2881 2882 wait_for_root_region_scanning(); 2883 2884 print_heap_before_gc(); 2885 print_heap_regions(); 2886 trace_heap_before_gc(_gc_tracer_stw); 2887 2888 _verifier->verify_region_sets_optional(); 2889 _verifier->verify_dirty_young_regions(); 2890 2891 // We should not be doing initial mark unless the conc mark thread is running 2892 if (!_cm_thread->should_terminate()) { 2893 // This call will decide whether this pause is an initial-mark 2894 // pause. If it is, in_initial_mark_gc() will return true 2895 // for the duration of this pause. 2896 g1_policy()->decide_on_conc_mark_initiation(); 2897 } 2898 2899 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2900 assert(!collector_state()->in_initial_mark_gc() || 2901 collector_state()->in_young_only_phase(), "sanity"); 2902 2903 // We also do not allow mixed GCs during marking. 2904 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2905 2906 // Record whether this pause is an initial mark. When the current 2907 // thread has completed its logging output and it's safe to signal 2908 // the CM thread, the flag's value in the policy has been reset. 2909 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2910 2911 // Inner scope for scope based logging, timers, and stats collection 2912 { 2913 G1EvacuationInfo evacuation_info; 2914 2915 if (collector_state()->in_initial_mark_gc()) { 2916 // We are about to start a marking cycle, so we increment the 2917 // full collection counter. 2918 increment_old_marking_cycles_started(); 2919 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2920 } 2921 2922 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2923 2924 GCTraceCPUTime tcpu; 2925 2926 G1HeapVerifier::G1VerifyType verify_type; 2927 FormatBuffer<> gc_string("Pause Young "); 2928 if (collector_state()->in_initial_mark_gc()) { 2929 gc_string.append("(Concurrent Start)"); 2930 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2931 } else if (collector_state()->in_young_only_phase()) { 2932 if (collector_state()->in_young_gc_before_mixed()) { 2933 gc_string.append("(Prepare Mixed)"); 2934 } else { 2935 gc_string.append("(Normal)"); 2936 } 2937 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2938 } else { 2939 gc_string.append("(Mixed)"); 2940 verify_type = G1HeapVerifier::G1VerifyMixed; 2941 } 2942 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2943 2944 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(), 2945 workers()->active_workers(), 2946 Threads::number_of_non_daemon_threads()); 2947 active_workers = workers()->update_active_workers(active_workers); 2948 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2949 2950 G1MonitoringScope ms(g1mm(), 2951 false /* full_gc */, 2952 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2953 2954 G1HeapTransition heap_transition(this); 2955 size_t heap_used_bytes_before_gc = used(); 2956 2957 // Don't dynamically change the number of GC threads this early. A value of 2958 // 0 is used to indicate serial work. When parallel work is done, 2959 // it will be set. 2960 2961 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2962 IsGCActiveMark x; 2963 2964 gc_prologue(false); 2965 2966 if (VerifyRememberedSets) { 2967 log_info(gc, verify)("[Verifying RemSets before GC]"); 2968 VerifyRegionRemSetClosure v_cl; 2969 heap_region_iterate(&v_cl); 2970 } 2971 2972 _verifier->verify_before_gc(verify_type); 2973 2974 _verifier->check_bitmaps("GC Start"); 2975 2976 #if COMPILER2_OR_JVMCI 2977 DerivedPointerTable::clear(); 2978 #endif 2979 2980 // Please see comment in g1CollectedHeap.hpp and 2981 // G1CollectedHeap::ref_processing_init() to see how 2982 // reference processing currently works in G1. 2983 2984 // Enable discovery in the STW reference processor 2985 _ref_processor_stw->enable_discovery(); 2986 2987 { 2988 // We want to temporarily turn off discovery by the 2989 // CM ref processor, if necessary, and turn it back on 2990 // on again later if we do. Using a scoped 2991 // NoRefDiscovery object will do this. 2992 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 2993 2994 // Forget the current alloc region (we might even choose it to be part 2995 // of the collection set!). 2996 _allocator->release_mutator_alloc_region(); 2997 2998 // This timing is only used by the ergonomics to handle our pause target. 2999 // It is unclear why this should not include the full pause. We will 3000 // investigate this in CR 7178365. 3001 // 3002 // Preserving the old comment here if that helps the investigation: 3003 // 3004 // The elapsed time induced by the start time below deliberately elides 3005 // the possible verification above. 3006 double sample_start_time_sec = os::elapsedTime(); 3007 3008 g1_policy()->record_collection_pause_start(sample_start_time_sec); 3009 3010 if (collector_state()->in_initial_mark_gc()) { 3011 concurrent_mark()->pre_initial_mark(); 3012 } 3013 3014 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 3015 3016 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3017 3018 register_humongous_regions_with_cset(); 3019 3020 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3021 3022 // We call this after finalize_cset() to 3023 // ensure that the CSet has been finalized. 3024 _cm->verify_no_cset_oops(); 3025 3026 if (_hr_printer.is_active()) { 3027 G1PrintCollectionSetClosure cl(&_hr_printer); 3028 _collection_set.iterate(&cl); 3029 } 3030 3031 // Initialize the GC alloc regions. 3032 _allocator->init_gc_alloc_regions(evacuation_info); 3033 3034 G1ParScanThreadStateSet per_thread_states(this, 3035 workers()->active_workers(), 3036 collection_set()->young_region_length(), 3037 collection_set()->optional_region_length()); 3038 pre_evacuate_collection_set(); 3039 3040 // Actually do the work... 3041 evacuate_collection_set(&per_thread_states); 3042 evacuate_optional_collection_set(&per_thread_states); 3043 3044 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3045 3046 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3047 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3048 3049 eagerly_reclaim_humongous_regions(); 3050 3051 record_obj_copy_mem_stats(); 3052 _survivor_evac_stats.adjust_desired_plab_sz(); 3053 _old_evac_stats.adjust_desired_plab_sz(); 3054 3055 double start = os::elapsedTime(); 3056 start_new_collection_set(); 3057 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3058 3059 if (evacuation_failed()) { 3060 double recalculate_used_start = os::elapsedTime(); 3061 set_used(recalculate_used()); 3062 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3063 3064 if (_archive_allocator != NULL) { 3065 _archive_allocator->clear_used(); 3066 } 3067 for (uint i = 0; i < ParallelGCThreads; i++) { 3068 if (_evacuation_failed_info_array[i].has_failed()) { 3069 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3070 } 3071 } 3072 } else { 3073 // The "used" of the the collection set have already been subtracted 3074 // when they were freed. Add in the bytes evacuated. 3075 increase_used(g1_policy()->bytes_copied_during_gc()); 3076 } 3077 3078 if (collector_state()->in_initial_mark_gc()) { 3079 // We have to do this before we notify the CM threads that 3080 // they can start working to make sure that all the 3081 // appropriate initialization is done on the CM object. 3082 concurrent_mark()->post_initial_mark(); 3083 // Note that we don't actually trigger the CM thread at 3084 // this point. We do that later when we're sure that 3085 // the current thread has completed its logging output. 3086 } 3087 3088 allocate_dummy_regions(); 3089 3090 _allocator->init_mutator_alloc_region(); 3091 3092 { 3093 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3094 if (expand_bytes > 0) { 3095 size_t bytes_before = capacity(); 3096 // No need for an ergo logging here, 3097 // expansion_amount() does this when it returns a value > 0. 3098 double expand_ms; 3099 if (!expand(expand_bytes, _workers, &expand_ms)) { 3100 // We failed to expand the heap. Cannot do anything about it. 3101 } 3102 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3103 } 3104 } 3105 3106 // We redo the verification but now wrt to the new CSet which 3107 // has just got initialized after the previous CSet was freed. 3108 _cm->verify_no_cset_oops(); 3109 3110 // This timing is only used by the ergonomics to handle our pause target. 3111 // It is unclear why this should not include the full pause. We will 3112 // investigate this in CR 7178365. 3113 double sample_end_time_sec = os::elapsedTime(); 3114 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3115 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3116 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3117 3118 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3119 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3120 3121 if (VerifyRememberedSets) { 3122 log_info(gc, verify)("[Verifying RemSets after GC]"); 3123 VerifyRegionRemSetClosure v_cl; 3124 heap_region_iterate(&v_cl); 3125 } 3126 3127 _verifier->verify_after_gc(verify_type); 3128 _verifier->check_bitmaps("GC End"); 3129 3130 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3131 _ref_processor_stw->verify_no_references_recorded(); 3132 3133 // CM reference discovery will be re-enabled if necessary. 3134 } 3135 3136 #ifdef TRACESPINNING 3137 ParallelTaskTerminator::print_termination_counts(); 3138 #endif 3139 3140 gc_epilogue(false); 3141 } 3142 3143 // Print the remainder of the GC log output. 3144 if (evacuation_failed()) { 3145 log_info(gc)("To-space exhausted"); 3146 } 3147 3148 g1_policy()->print_phases(); 3149 heap_transition.print(); 3150 3151 // It is not yet to safe to tell the concurrent mark to 3152 // start as we have some optional output below. We don't want the 3153 // output from the concurrent mark thread interfering with this 3154 // logging output either. 3155 3156 _hrm->verify_optional(); 3157 _verifier->verify_region_sets_optional(); 3158 3159 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3160 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3161 3162 print_heap_after_gc(); 3163 print_heap_regions(); 3164 trace_heap_after_gc(_gc_tracer_stw); 3165 3166 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3167 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3168 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3169 // before any GC notifications are raised. 3170 g1mm()->update_sizes(); 3171 3172 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3173 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3174 _gc_timer_stw->register_gc_end(); 3175 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3176 } 3177 // It should now be safe to tell the concurrent mark thread to start 3178 // without its logging output interfering with the logging output 3179 // that came from the pause. 3180 3181 if (should_start_conc_mark) { 3182 // CAUTION: after the doConcurrentMark() call below, 3183 // the concurrent marking thread(s) could be running 3184 // concurrently with us. Make sure that anything after 3185 // this point does not assume that we are the only GC thread 3186 // running. Note: of course, the actual marking work will 3187 // not start until the safepoint itself is released in 3188 // SuspendibleThreadSet::desynchronize(). 3189 do_concurrent_mark(); 3190 } 3191 3192 return true; 3193 } 3194 3195 void G1CollectedHeap::remove_self_forwarding_pointers() { 3196 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3197 workers()->run_task(&rsfp_task); 3198 } 3199 3200 void G1CollectedHeap::restore_after_evac_failure() { 3201 double remove_self_forwards_start = os::elapsedTime(); 3202 3203 remove_self_forwarding_pointers(); 3204 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3205 _preserved_marks_set.restore(&task_executor); 3206 3207 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3208 } 3209 3210 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3211 if (!_evacuation_failed) { 3212 _evacuation_failed = true; 3213 } 3214 3215 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3216 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3217 } 3218 3219 bool G1ParEvacuateFollowersClosure::offer_termination() { 3220 EventGCPhaseParallel event; 3221 G1ParScanThreadState* const pss = par_scan_state(); 3222 start_term_time(); 3223 const bool res = terminator()->offer_termination(); 3224 end_term_time(); 3225 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3226 return res; 3227 } 3228 3229 void G1ParEvacuateFollowersClosure::do_void() { 3230 EventGCPhaseParallel event; 3231 G1ParScanThreadState* const pss = par_scan_state(); 3232 pss->trim_queue(); 3233 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3234 do { 3235 EventGCPhaseParallel event; 3236 pss->steal_and_trim_queue(queues()); 3237 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3238 } while (!offer_termination()); 3239 } 3240 3241 class G1ParTask : public AbstractGangTask { 3242 protected: 3243 G1CollectedHeap* _g1h; 3244 G1ParScanThreadStateSet* _pss; 3245 RefToScanQueueSet* _queues; 3246 G1RootProcessor* _root_processor; 3247 TaskTerminator _terminator; 3248 uint _n_workers; 3249 3250 public: 3251 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3252 : AbstractGangTask("G1 collection"), 3253 _g1h(g1h), 3254 _pss(per_thread_states), 3255 _queues(task_queues), 3256 _root_processor(root_processor), 3257 _terminator(n_workers, _queues), 3258 _n_workers(n_workers) 3259 {} 3260 3261 void work(uint worker_id) { 3262 if (worker_id >= _n_workers) return; // no work needed this round 3263 3264 double start_sec = os::elapsedTime(); 3265 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3266 3267 { 3268 ResourceMark rm; 3269 HandleMark hm; 3270 3271 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3272 3273 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3274 pss->set_ref_discoverer(rp); 3275 3276 double start_strong_roots_sec = os::elapsedTime(); 3277 3278 _root_processor->evacuate_roots(pss, worker_id); 3279 3280 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3281 3282 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3283 3284 double term_sec = 0.0; 3285 size_t evac_term_attempts = 0; 3286 { 3287 double start = os::elapsedTime(); 3288 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy); 3289 evac.do_void(); 3290 3291 evac_term_attempts = evac.term_attempts(); 3292 term_sec = evac.term_time(); 3293 double elapsed_sec = os::elapsedTime() - start; 3294 3295 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3296 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3297 3298 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy, 3299 worker_id, 3300 pss->lab_waste_words() * HeapWordSize, 3301 G1GCPhaseTimes::ObjCopyLABWaste); 3302 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy, 3303 worker_id, 3304 pss->lab_undo_waste_words() * HeapWordSize, 3305 G1GCPhaseTimes::ObjCopyLABUndoWaste); 3306 3307 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3308 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3309 } 3310 3311 assert(pss->queue_is_empty(), "should be empty"); 3312 3313 // Close the inner scope so that the ResourceMark and HandleMark 3314 // destructors are executed here and are included as part of the 3315 // "GC Worker Time". 3316 } 3317 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3318 } 3319 }; 3320 3321 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3322 bool class_unloading_occurred) { 3323 uint num_workers = workers()->active_workers(); 3324 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false); 3325 workers()->run_task(&unlink_task); 3326 } 3327 3328 // Clean string dedup data structures. 3329 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to 3330 // record the durations of the phases. Hence the almost-copy. 3331 class G1StringDedupCleaningTask : public AbstractGangTask { 3332 BoolObjectClosure* _is_alive; 3333 OopClosure* _keep_alive; 3334 G1GCPhaseTimes* _phase_times; 3335 3336 public: 3337 G1StringDedupCleaningTask(BoolObjectClosure* is_alive, 3338 OopClosure* keep_alive, 3339 G1GCPhaseTimes* phase_times) : 3340 AbstractGangTask("Partial Cleaning Task"), 3341 _is_alive(is_alive), 3342 _keep_alive(keep_alive), 3343 _phase_times(phase_times) 3344 { 3345 assert(G1StringDedup::is_enabled(), "String deduplication disabled."); 3346 StringDedup::gc_prologue(true); 3347 } 3348 3349 ~G1StringDedupCleaningTask() { 3350 StringDedup::gc_epilogue(); 3351 } 3352 3353 void work(uint worker_id) { 3354 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive); 3355 { 3356 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id); 3357 StringDedupQueue::unlink_or_oops_do(&cl); 3358 } 3359 { 3360 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id); 3361 StringDedupTable::unlink_or_oops_do(&cl, worker_id); 3362 } 3363 } 3364 }; 3365 3366 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive, 3367 OopClosure* keep_alive, 3368 G1GCPhaseTimes* phase_times) { 3369 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times); 3370 workers()->run_task(&cl); 3371 } 3372 3373 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3374 private: 3375 G1DirtyCardQueueSet* _queue; 3376 G1CollectedHeap* _g1h; 3377 public: 3378 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3379 _queue(queue), _g1h(g1h) { } 3380 3381 virtual void work(uint worker_id) { 3382 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3383 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3384 3385 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3386 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3387 3388 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3389 } 3390 }; 3391 3392 void G1CollectedHeap::redirty_logged_cards() { 3393 double redirty_logged_cards_start = os::elapsedTime(); 3394 3395 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3396 dirty_card_queue_set().reset_for_par_iteration(); 3397 workers()->run_task(&redirty_task); 3398 3399 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3400 dcq.merge_bufferlists(&dirty_card_queue_set()); 3401 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3402 3403 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3404 } 3405 3406 // Weak Reference Processing support 3407 3408 bool G1STWIsAliveClosure::do_object_b(oop p) { 3409 // An object is reachable if it is outside the collection set, 3410 // or is inside and copied. 3411 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3412 } 3413 3414 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3415 assert(obj != NULL, "must not be NULL"); 3416 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3417 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3418 // may falsely indicate that this is not the case here: however the collection set only 3419 // contains old regions when concurrent mark is not running. 3420 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3421 } 3422 3423 // Non Copying Keep Alive closure 3424 class G1KeepAliveClosure: public OopClosure { 3425 G1CollectedHeap*_g1h; 3426 public: 3427 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3428 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3429 void do_oop(oop* p) { 3430 oop obj = *p; 3431 assert(obj != NULL, "the caller should have filtered out NULL values"); 3432 3433 const InCSetState cset_state =_g1h->in_cset_state(obj); 3434 if (!cset_state.is_in_cset_or_humongous()) { 3435 return; 3436 } 3437 if (cset_state.is_in_cset()) { 3438 assert( obj->is_forwarded(), "invariant" ); 3439 *p = obj->forwardee(); 3440 } else { 3441 assert(!obj->is_forwarded(), "invariant" ); 3442 assert(cset_state.is_humongous(), 3443 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3444 _g1h->set_humongous_is_live(obj); 3445 } 3446 } 3447 }; 3448 3449 // Copying Keep Alive closure - can be called from both 3450 // serial and parallel code as long as different worker 3451 // threads utilize different G1ParScanThreadState instances 3452 // and different queues. 3453 3454 class G1CopyingKeepAliveClosure: public OopClosure { 3455 G1CollectedHeap* _g1h; 3456 G1ParScanThreadState* _par_scan_state; 3457 3458 public: 3459 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3460 G1ParScanThreadState* pss): 3461 _g1h(g1h), 3462 _par_scan_state(pss) 3463 {} 3464 3465 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3466 virtual void do_oop( oop* p) { do_oop_work(p); } 3467 3468 template <class T> void do_oop_work(T* p) { 3469 oop obj = RawAccess<>::oop_load(p); 3470 3471 if (_g1h->is_in_cset_or_humongous(obj)) { 3472 // If the referent object has been forwarded (either copied 3473 // to a new location or to itself in the event of an 3474 // evacuation failure) then we need to update the reference 3475 // field and, if both reference and referent are in the G1 3476 // heap, update the RSet for the referent. 3477 // 3478 // If the referent has not been forwarded then we have to keep 3479 // it alive by policy. Therefore we have copy the referent. 3480 // 3481 // When the queue is drained (after each phase of reference processing) 3482 // the object and it's followers will be copied, the reference field set 3483 // to point to the new location, and the RSet updated. 3484 _par_scan_state->push_on_queue(p); 3485 } 3486 } 3487 }; 3488 3489 // Serial drain queue closure. Called as the 'complete_gc' 3490 // closure for each discovered list in some of the 3491 // reference processing phases. 3492 3493 class G1STWDrainQueueClosure: public VoidClosure { 3494 protected: 3495 G1CollectedHeap* _g1h; 3496 G1ParScanThreadState* _par_scan_state; 3497 3498 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3499 3500 public: 3501 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3502 _g1h(g1h), 3503 _par_scan_state(pss) 3504 { } 3505 3506 void do_void() { 3507 G1ParScanThreadState* const pss = par_scan_state(); 3508 pss->trim_queue(); 3509 } 3510 }; 3511 3512 // Parallel Reference Processing closures 3513 3514 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3515 // processing during G1 evacuation pauses. 3516 3517 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3518 private: 3519 G1CollectedHeap* _g1h; 3520 G1ParScanThreadStateSet* _pss; 3521 RefToScanQueueSet* _queues; 3522 WorkGang* _workers; 3523 3524 public: 3525 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3526 G1ParScanThreadStateSet* per_thread_states, 3527 WorkGang* workers, 3528 RefToScanQueueSet *task_queues) : 3529 _g1h(g1h), 3530 _pss(per_thread_states), 3531 _queues(task_queues), 3532 _workers(workers) 3533 { 3534 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3535 } 3536 3537 // Executes the given task using concurrent marking worker threads. 3538 virtual void execute(ProcessTask& task, uint ergo_workers); 3539 }; 3540 3541 // Gang task for possibly parallel reference processing 3542 3543 class G1STWRefProcTaskProxy: public AbstractGangTask { 3544 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3545 ProcessTask& _proc_task; 3546 G1CollectedHeap* _g1h; 3547 G1ParScanThreadStateSet* _pss; 3548 RefToScanQueueSet* _task_queues; 3549 ParallelTaskTerminator* _terminator; 3550 3551 public: 3552 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3553 G1CollectedHeap* g1h, 3554 G1ParScanThreadStateSet* per_thread_states, 3555 RefToScanQueueSet *task_queues, 3556 ParallelTaskTerminator* terminator) : 3557 AbstractGangTask("Process reference objects in parallel"), 3558 _proc_task(proc_task), 3559 _g1h(g1h), 3560 _pss(per_thread_states), 3561 _task_queues(task_queues), 3562 _terminator(terminator) 3563 {} 3564 3565 virtual void work(uint worker_id) { 3566 // The reference processing task executed by a single worker. 3567 ResourceMark rm; 3568 HandleMark hm; 3569 3570 G1STWIsAliveClosure is_alive(_g1h); 3571 3572 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3573 pss->set_ref_discoverer(NULL); 3574 3575 // Keep alive closure. 3576 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3577 3578 // Complete GC closure 3579 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3580 3581 // Call the reference processing task's work routine. 3582 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3583 3584 // Note we cannot assert that the refs array is empty here as not all 3585 // of the processing tasks (specifically phase2 - pp2_work) execute 3586 // the complete_gc closure (which ordinarily would drain the queue) so 3587 // the queue may not be empty. 3588 } 3589 }; 3590 3591 // Driver routine for parallel reference processing. 3592 // Creates an instance of the ref processing gang 3593 // task and has the worker threads execute it. 3594 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3595 assert(_workers != NULL, "Need parallel worker threads."); 3596 3597 assert(_workers->active_workers() >= ergo_workers, 3598 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3599 ergo_workers, _workers->active_workers()); 3600 TaskTerminator terminator(ergo_workers, _queues); 3601 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator()); 3602 3603 _workers->run_task(&proc_task_proxy, ergo_workers); 3604 } 3605 3606 // End of weak reference support closures 3607 3608 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3609 double ref_proc_start = os::elapsedTime(); 3610 3611 ReferenceProcessor* rp = _ref_processor_stw; 3612 assert(rp->discovery_enabled(), "should have been enabled"); 3613 3614 // Closure to test whether a referent is alive. 3615 G1STWIsAliveClosure is_alive(this); 3616 3617 // Even when parallel reference processing is enabled, the processing 3618 // of JNI refs is serial and performed serially by the current thread 3619 // rather than by a worker. The following PSS will be used for processing 3620 // JNI refs. 3621 3622 // Use only a single queue for this PSS. 3623 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3624 pss->set_ref_discoverer(NULL); 3625 assert(pss->queue_is_empty(), "pre-condition"); 3626 3627 // Keep alive closure. 3628 G1CopyingKeepAliveClosure keep_alive(this, pss); 3629 3630 // Serial Complete GC closure 3631 G1STWDrainQueueClosure drain_queue(this, pss); 3632 3633 // Setup the soft refs policy... 3634 rp->setup_policy(false); 3635 3636 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3637 3638 ReferenceProcessorStats stats; 3639 if (!rp->processing_is_mt()) { 3640 // Serial reference processing... 3641 stats = rp->process_discovered_references(&is_alive, 3642 &keep_alive, 3643 &drain_queue, 3644 NULL, 3645 pt); 3646 } else { 3647 uint no_of_gc_workers = workers()->active_workers(); 3648 3649 // Parallel reference processing 3650 assert(no_of_gc_workers <= rp->max_num_queues(), 3651 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3652 no_of_gc_workers, rp->max_num_queues()); 3653 3654 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3655 stats = rp->process_discovered_references(&is_alive, 3656 &keep_alive, 3657 &drain_queue, 3658 &par_task_executor, 3659 pt); 3660 } 3661 3662 _gc_tracer_stw->report_gc_reference_stats(stats); 3663 3664 // We have completed copying any necessary live referent objects. 3665 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3666 3667 make_pending_list_reachable(); 3668 3669 rp->verify_no_references_recorded(); 3670 3671 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3672 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3673 } 3674 3675 void G1CollectedHeap::make_pending_list_reachable() { 3676 if (collector_state()->in_initial_mark_gc()) { 3677 oop pll_head = Universe::reference_pending_list(); 3678 if (pll_head != NULL) { 3679 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3680 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3681 } 3682 } 3683 } 3684 3685 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3686 double merge_pss_time_start = os::elapsedTime(); 3687 per_thread_states->flush(); 3688 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3689 } 3690 3691 void G1CollectedHeap::pre_evacuate_collection_set() { 3692 _expand_heap_after_alloc_failure = true; 3693 _evacuation_failed = false; 3694 3695 // Disable the hot card cache. 3696 _hot_card_cache->reset_hot_cache_claimed_index(); 3697 _hot_card_cache->set_use_cache(false); 3698 3699 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3700 _preserved_marks_set.assert_empty(); 3701 3702 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3703 3704 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3705 if (collector_state()->in_initial_mark_gc()) { 3706 double start_clear_claimed_marks = os::elapsedTime(); 3707 3708 ClassLoaderDataGraph::clear_claimed_marks(); 3709 3710 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3711 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3712 } 3713 } 3714 3715 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3716 // Should G1EvacuationFailureALot be in effect for this GC? 3717 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3718 3719 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3720 3721 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3722 3723 double start_par_time_sec = os::elapsedTime(); 3724 double end_par_time_sec; 3725 3726 { 3727 const uint n_workers = workers()->active_workers(); 3728 G1RootProcessor root_processor(this, n_workers); 3729 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3730 3731 workers()->run_task(&g1_par_task); 3732 end_par_time_sec = os::elapsedTime(); 3733 3734 // Closing the inner scope will execute the destructor 3735 // for the G1RootProcessor object. We record the current 3736 // elapsed time before closing the scope so that time 3737 // taken for the destructor is NOT included in the 3738 // reported parallel time. 3739 } 3740 3741 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3742 phase_times->record_par_time(par_time_ms); 3743 3744 double code_root_fixup_time_ms = 3745 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3746 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 3747 } 3748 3749 class G1EvacuateOptionalRegionTask : public AbstractGangTask { 3750 G1CollectedHeap* _g1h; 3751 G1ParScanThreadStateSet* _per_thread_states; 3752 G1OptionalCSet* _optional; 3753 RefToScanQueueSet* _queues; 3754 ParallelTaskTerminator _terminator; 3755 3756 Tickspan trim_ticks(G1ParScanThreadState* pss) { 3757 Tickspan copy_time = pss->trim_ticks(); 3758 pss->reset_trim_ticks(); 3759 return copy_time; 3760 } 3761 3762 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3763 G1EvacuationRootClosures* root_cls = pss->closures(); 3764 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss); 3765 3766 size_t scanned = 0; 3767 size_t claimed = 0; 3768 size_t skipped = 0; 3769 size_t used_memory = 0; 3770 3771 Ticks start = Ticks::now(); 3772 Tickspan copy_time; 3773 3774 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) { 3775 HeapRegion* hr = _optional->region_at(i); 3776 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl); 3777 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops()); 3778 copy_time += trim_ticks(pss); 3779 3780 G1ScanRSForRegionClosure scan_rs_cl(_g1h->g1_rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id); 3781 scan_rs_cl.do_heap_region(hr); 3782 copy_time += trim_ticks(pss); 3783 scanned += scan_rs_cl.cards_scanned(); 3784 claimed += scan_rs_cl.cards_claimed(); 3785 skipped += scan_rs_cl.cards_skipped(); 3786 3787 // Chunk lists for this region is no longer needed. 3788 used_memory += pss->oops_into_optional_region(hr)->used_memory(); 3789 } 3790 3791 Tickspan scan_time = (Ticks::now() - start) - copy_time; 3792 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3793 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds()); 3794 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds()); 3795 3796 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards); 3797 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards); 3798 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards); 3799 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory); 3800 } 3801 3802 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3803 Ticks start = Ticks::now(); 3804 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy); 3805 cl.do_void(); 3806 3807 Tickspan evac_time = (Ticks::now() - start); 3808 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3809 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds()); 3810 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation"); 3811 } 3812 3813 public: 3814 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h, 3815 G1ParScanThreadStateSet* per_thread_states, 3816 G1OptionalCSet* cset, 3817 RefToScanQueueSet* queues, 3818 uint n_workers) : 3819 AbstractGangTask("G1 Evacuation Optional Region Task"), 3820 _g1h(g1h), 3821 _per_thread_states(per_thread_states), 3822 _optional(cset), 3823 _queues(queues), 3824 _terminator(n_workers, _queues) { 3825 } 3826 3827 void work(uint worker_id) { 3828 ResourceMark rm; 3829 HandleMark hm; 3830 3831 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3832 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3833 3834 scan_roots(pss, worker_id); 3835 evacuate_live_objects(pss, worker_id); 3836 } 3837 }; 3838 3839 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) { 3840 class G1MarkScope : public MarkScope {}; 3841 G1MarkScope code_mark_scope; 3842 3843 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers()); 3844 workers()->run_task(&task); 3845 } 3846 3847 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3848 G1OptionalCSet optional_cset(&_collection_set, per_thread_states); 3849 if (optional_cset.is_empty()) { 3850 return; 3851 } 3852 3853 if (evacuation_failed()) { 3854 return; 3855 } 3856 3857 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3858 const double gc_start_time_ms = phase_times->cur_collection_start_sec() * 1000.0; 3859 3860 double start_time_sec = os::elapsedTime(); 3861 3862 do { 3863 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3864 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3865 3866 if (time_left_ms < 0) { 3867 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms); 3868 break; 3869 } 3870 3871 optional_cset.prepare_evacuation(time_left_ms * _g1_policy->optional_evacuation_fraction()); 3872 if (optional_cset.prepare_failed()) { 3873 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms); 3874 break; 3875 } 3876 3877 evacuate_optional_regions(per_thread_states, &optional_cset); 3878 3879 optional_cset.complete_evacuation(); 3880 if (optional_cset.evacuation_failed()) { 3881 break; 3882 } 3883 } while (!optional_cset.is_empty()); 3884 3885 phase_times->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0); 3886 } 3887 3888 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3889 // Also cleans the card table from temporary duplicate detection information used 3890 // during UpdateRS/ScanRS. 3891 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 3892 3893 // Process any discovered reference objects - we have 3894 // to do this _before_ we retire the GC alloc regions 3895 // as we may have to copy some 'reachable' referent 3896 // objects (and their reachable sub-graphs) that were 3897 // not copied during the pause. 3898 process_discovered_references(per_thread_states); 3899 3900 G1STWIsAliveClosure is_alive(this); 3901 G1KeepAliveClosure keep_alive(this); 3902 3903 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3904 g1_policy()->phase_times()->weak_phase_times()); 3905 3906 if (G1StringDedup::is_enabled()) { 3907 double string_dedup_time_ms = os::elapsedTime(); 3908 3909 string_dedup_cleaning(&is_alive, &keep_alive, g1_policy()->phase_times()); 3910 3911 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0; 3912 g1_policy()->phase_times()->record_string_deduplication_time(string_cleanup_time_ms); 3913 } 3914 3915 if (evacuation_failed()) { 3916 restore_after_evac_failure(); 3917 3918 // Reset the G1EvacuationFailureALot counters and flags 3919 // Note: the values are reset only when an actual 3920 // evacuation failure occurs. 3921 NOT_PRODUCT(reset_evacuation_should_fail();) 3922 } 3923 3924 _preserved_marks_set.assert_empty(); 3925 3926 _allocator->release_gc_alloc_regions(evacuation_info); 3927 3928 merge_per_thread_state_info(per_thread_states); 3929 3930 // Reset and re-enable the hot card cache. 3931 // Note the counts for the cards in the regions in the 3932 // collection set are reset when the collection set is freed. 3933 _hot_card_cache->reset_hot_cache(); 3934 _hot_card_cache->set_use_cache(true); 3935 3936 purge_code_root_memory(); 3937 3938 redirty_logged_cards(); 3939 #if COMPILER2_OR_JVMCI 3940 double start = os::elapsedTime(); 3941 DerivedPointerTable::update_pointers(); 3942 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3943 #endif 3944 g1_policy()->print_age_table(); 3945 } 3946 3947 void G1CollectedHeap::record_obj_copy_mem_stats() { 3948 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3949 3950 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3951 create_g1_evac_summary(&_old_evac_stats)); 3952 } 3953 3954 void G1CollectedHeap::free_region(HeapRegion* hr, 3955 FreeRegionList* free_list, 3956 bool skip_remset, 3957 bool skip_hot_card_cache, 3958 bool locked) { 3959 assert(!hr->is_free(), "the region should not be free"); 3960 assert(!hr->is_empty(), "the region should not be empty"); 3961 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3962 assert(free_list != NULL, "pre-condition"); 3963 3964 if (G1VerifyBitmaps) { 3965 MemRegion mr(hr->bottom(), hr->end()); 3966 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3967 } 3968 3969 // Clear the card counts for this region. 3970 // Note: we only need to do this if the region is not young 3971 // (since we don't refine cards in young regions). 3972 if (!skip_hot_card_cache && !hr->is_young()) { 3973 _hot_card_cache->reset_card_counts(hr); 3974 } 3975 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3976 _g1_policy->remset_tracker()->update_at_free(hr); 3977 free_list->add_ordered(hr); 3978 } 3979 3980 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3981 FreeRegionList* free_list) { 3982 assert(hr->is_humongous(), "this is only for humongous regions"); 3983 assert(free_list != NULL, "pre-condition"); 3984 hr->clear_humongous(); 3985 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3986 } 3987 3988 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3989 const uint humongous_regions_removed) { 3990 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3991 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3992 _old_set.bulk_remove(old_regions_removed); 3993 _humongous_set.bulk_remove(humongous_regions_removed); 3994 } 3995 3996 } 3997 3998 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3999 assert(list != NULL, "list can't be null"); 4000 if (!list->is_empty()) { 4001 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4002 _hrm->insert_list_into_free_list(list); 4003 } 4004 } 4005 4006 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4007 decrease_used(bytes); 4008 } 4009 4010 class G1FreeCollectionSetTask : public AbstractGangTask { 4011 private: 4012 4013 // Closure applied to all regions in the collection set to do work that needs to 4014 // be done serially in a single thread. 4015 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4016 private: 4017 G1EvacuationInfo* _evacuation_info; 4018 const size_t* _surviving_young_words; 4019 4020 // Bytes used in successfully evacuated regions before the evacuation. 4021 size_t _before_used_bytes; 4022 // Bytes used in unsucessfully evacuated regions before the evacuation 4023 size_t _after_used_bytes; 4024 4025 size_t _bytes_allocated_in_old_since_last_gc; 4026 4027 size_t _failure_used_words; 4028 size_t _failure_waste_words; 4029 4030 FreeRegionList _local_free_list; 4031 public: 4032 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4033 HeapRegionClosure(), 4034 _evacuation_info(evacuation_info), 4035 _surviving_young_words(surviving_young_words), 4036 _before_used_bytes(0), 4037 _after_used_bytes(0), 4038 _bytes_allocated_in_old_since_last_gc(0), 4039 _failure_used_words(0), 4040 _failure_waste_words(0), 4041 _local_free_list("Local Region List for CSet Freeing") { 4042 } 4043 4044 virtual bool do_heap_region(HeapRegion* r) { 4045 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4046 4047 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4048 g1h->clear_in_cset(r); 4049 4050 if (r->is_young()) { 4051 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4052 "Young index %d is wrong for region %u of type %s with %u young regions", 4053 r->young_index_in_cset(), 4054 r->hrm_index(), 4055 r->get_type_str(), 4056 g1h->collection_set()->young_region_length()); 4057 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4058 r->record_surv_words_in_group(words_survived); 4059 } 4060 4061 if (!r->evacuation_failed()) { 4062 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4063 _before_used_bytes += r->used(); 4064 g1h->free_region(r, 4065 &_local_free_list, 4066 true, /* skip_remset */ 4067 true, /* skip_hot_card_cache */ 4068 true /* locked */); 4069 } else { 4070 r->uninstall_surv_rate_group(); 4071 r->set_young_index_in_cset(-1); 4072 r->set_evacuation_failed(false); 4073 // When moving a young gen region to old gen, we "allocate" that whole region 4074 // there. This is in addition to any already evacuated objects. Notify the 4075 // policy about that. 4076 // Old gen regions do not cause an additional allocation: both the objects 4077 // still in the region and the ones already moved are accounted for elsewhere. 4078 if (r->is_young()) { 4079 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4080 } 4081 // The region is now considered to be old. 4082 r->set_old(); 4083 // Do some allocation statistics accounting. Regions that failed evacuation 4084 // are always made old, so there is no need to update anything in the young 4085 // gen statistics, but we need to update old gen statistics. 4086 size_t used_words = r->marked_bytes() / HeapWordSize; 4087 4088 _failure_used_words += used_words; 4089 _failure_waste_words += HeapRegion::GrainWords - used_words; 4090 4091 g1h->old_set_add(r); 4092 _after_used_bytes += r->used(); 4093 } 4094 return false; 4095 } 4096 4097 void complete_work() { 4098 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4099 4100 _evacuation_info->set_regions_freed(_local_free_list.length()); 4101 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4102 4103 g1h->prepend_to_freelist(&_local_free_list); 4104 g1h->decrement_summary_bytes(_before_used_bytes); 4105 4106 G1Policy* policy = g1h->g1_policy(); 4107 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4108 4109 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4110 } 4111 }; 4112 4113 G1CollectionSet* _collection_set; 4114 G1SerialFreeCollectionSetClosure _cl; 4115 const size_t* _surviving_young_words; 4116 4117 size_t _rs_lengths; 4118 4119 volatile jint _serial_work_claim; 4120 4121 struct WorkItem { 4122 uint region_idx; 4123 bool is_young; 4124 bool evacuation_failed; 4125 4126 WorkItem(HeapRegion* r) { 4127 region_idx = r->hrm_index(); 4128 is_young = r->is_young(); 4129 evacuation_failed = r->evacuation_failed(); 4130 } 4131 }; 4132 4133 volatile size_t _parallel_work_claim; 4134 size_t _num_work_items; 4135 WorkItem* _work_items; 4136 4137 void do_serial_work() { 4138 // Need to grab the lock to be allowed to modify the old region list. 4139 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4140 _collection_set->iterate(&_cl); 4141 } 4142 4143 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4144 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4145 4146 HeapRegion* r = g1h->region_at(region_idx); 4147 assert(!g1h->is_on_master_free_list(r), "sanity"); 4148 4149 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4150 4151 if (!is_young) { 4152 g1h->_hot_card_cache->reset_card_counts(r); 4153 } 4154 4155 if (!evacuation_failed) { 4156 r->rem_set()->clear_locked(); 4157 } 4158 } 4159 4160 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4161 private: 4162 size_t _cur_idx; 4163 WorkItem* _work_items; 4164 public: 4165 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4166 4167 virtual bool do_heap_region(HeapRegion* r) { 4168 _work_items[_cur_idx++] = WorkItem(r); 4169 return false; 4170 } 4171 }; 4172 4173 void prepare_work() { 4174 G1PrepareFreeCollectionSetClosure cl(_work_items); 4175 _collection_set->iterate(&cl); 4176 } 4177 4178 void complete_work() { 4179 _cl.complete_work(); 4180 4181 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4182 policy->record_max_rs_lengths(_rs_lengths); 4183 policy->cset_regions_freed(); 4184 } 4185 public: 4186 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4187 AbstractGangTask("G1 Free Collection Set"), 4188 _collection_set(collection_set), 4189 _cl(evacuation_info, surviving_young_words), 4190 _surviving_young_words(surviving_young_words), 4191 _rs_lengths(0), 4192 _serial_work_claim(0), 4193 _parallel_work_claim(0), 4194 _num_work_items(collection_set->region_length()), 4195 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4196 prepare_work(); 4197 } 4198 4199 ~G1FreeCollectionSetTask() { 4200 complete_work(); 4201 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4202 } 4203 4204 // Chunk size for work distribution. The chosen value has been determined experimentally 4205 // to be a good tradeoff between overhead and achievable parallelism. 4206 static uint chunk_size() { return 32; } 4207 4208 virtual void work(uint worker_id) { 4209 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4210 4211 // Claim serial work. 4212 if (_serial_work_claim == 0) { 4213 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4214 if (value == 0) { 4215 double serial_time = os::elapsedTime(); 4216 do_serial_work(); 4217 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4218 } 4219 } 4220 4221 // Start parallel work. 4222 double young_time = 0.0; 4223 bool has_young_time = false; 4224 double non_young_time = 0.0; 4225 bool has_non_young_time = false; 4226 4227 while (true) { 4228 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4229 size_t cur = end - chunk_size(); 4230 4231 if (cur >= _num_work_items) { 4232 break; 4233 } 4234 4235 EventGCPhaseParallel event; 4236 double start_time = os::elapsedTime(); 4237 4238 end = MIN2(end, _num_work_items); 4239 4240 for (; cur < end; cur++) { 4241 bool is_young = _work_items[cur].is_young; 4242 4243 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4244 4245 double end_time = os::elapsedTime(); 4246 double time_taken = end_time - start_time; 4247 if (is_young) { 4248 young_time += time_taken; 4249 has_young_time = true; 4250 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4251 } else { 4252 non_young_time += time_taken; 4253 has_non_young_time = true; 4254 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4255 } 4256 start_time = end_time; 4257 } 4258 } 4259 4260 if (has_young_time) { 4261 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4262 } 4263 if (has_non_young_time) { 4264 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4265 } 4266 } 4267 }; 4268 4269 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4270 _eden.clear(); 4271 4272 double free_cset_start_time = os::elapsedTime(); 4273 4274 { 4275 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4276 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4277 4278 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4279 4280 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4281 cl.name(), 4282 num_workers, 4283 _collection_set.region_length()); 4284 workers()->run_task(&cl, num_workers); 4285 } 4286 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4287 4288 collection_set->clear(); 4289 } 4290 4291 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4292 private: 4293 FreeRegionList* _free_region_list; 4294 HeapRegionSet* _proxy_set; 4295 uint _humongous_objects_reclaimed; 4296 uint _humongous_regions_reclaimed; 4297 size_t _freed_bytes; 4298 public: 4299 4300 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4301 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4302 } 4303 4304 virtual bool do_heap_region(HeapRegion* r) { 4305 if (!r->is_starts_humongous()) { 4306 return false; 4307 } 4308 4309 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4310 4311 oop obj = (oop)r->bottom(); 4312 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4313 4314 // The following checks whether the humongous object is live are sufficient. 4315 // The main additional check (in addition to having a reference from the roots 4316 // or the young gen) is whether the humongous object has a remembered set entry. 4317 // 4318 // A humongous object cannot be live if there is no remembered set for it 4319 // because: 4320 // - there can be no references from within humongous starts regions referencing 4321 // the object because we never allocate other objects into them. 4322 // (I.e. there are no intra-region references that may be missed by the 4323 // remembered set) 4324 // - as soon there is a remembered set entry to the humongous starts region 4325 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4326 // until the end of a concurrent mark. 4327 // 4328 // It is not required to check whether the object has been found dead by marking 4329 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4330 // all objects allocated during that time are considered live. 4331 // SATB marking is even more conservative than the remembered set. 4332 // So if at this point in the collection there is no remembered set entry, 4333 // nobody has a reference to it. 4334 // At the start of collection we flush all refinement logs, and remembered sets 4335 // are completely up-to-date wrt to references to the humongous object. 4336 // 4337 // Other implementation considerations: 4338 // - never consider object arrays at this time because they would pose 4339 // considerable effort for cleaning up the the remembered sets. This is 4340 // required because stale remembered sets might reference locations that 4341 // are currently allocated into. 4342 uint region_idx = r->hrm_index(); 4343 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4344 !r->rem_set()->is_empty()) { 4345 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", 4346 region_idx, 4347 (size_t)obj->size() * HeapWordSize, 4348 p2i(r->bottom()), 4349 r->rem_set()->occupied(), 4350 r->rem_set()->strong_code_roots_list_length(), 4351 next_bitmap->is_marked(r->bottom()), 4352 g1h->is_humongous_reclaim_candidate(region_idx), 4353 obj->is_typeArray() 4354 ); 4355 return false; 4356 } 4357 4358 guarantee(obj->is_typeArray(), 4359 "Only eagerly reclaiming type arrays is supported, but the object " 4360 PTR_FORMAT " is not.", p2i(r->bottom())); 4361 4362 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", 4363 region_idx, 4364 (size_t)obj->size() * HeapWordSize, 4365 p2i(r->bottom()), 4366 r->rem_set()->occupied(), 4367 r->rem_set()->strong_code_roots_list_length(), 4368 next_bitmap->is_marked(r->bottom()), 4369 g1h->is_humongous_reclaim_candidate(region_idx), 4370 obj->is_typeArray() 4371 ); 4372 4373 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4374 cm->humongous_object_eagerly_reclaimed(r); 4375 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4376 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4377 region_idx, 4378 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4379 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4380 _humongous_objects_reclaimed++; 4381 do { 4382 HeapRegion* next = g1h->next_region_in_humongous(r); 4383 _freed_bytes += r->used(); 4384 r->set_containing_set(NULL); 4385 _humongous_regions_reclaimed++; 4386 g1h->free_humongous_region(r, _free_region_list); 4387 r = next; 4388 } while (r != NULL); 4389 4390 return false; 4391 } 4392 4393 uint humongous_objects_reclaimed() { 4394 return _humongous_objects_reclaimed; 4395 } 4396 4397 uint humongous_regions_reclaimed() { 4398 return _humongous_regions_reclaimed; 4399 } 4400 4401 size_t bytes_freed() const { 4402 return _freed_bytes; 4403 } 4404 }; 4405 4406 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4407 assert_at_safepoint_on_vm_thread(); 4408 4409 if (!G1EagerReclaimHumongousObjects || 4410 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4411 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4412 return; 4413 } 4414 4415 double start_time = os::elapsedTime(); 4416 4417 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4418 4419 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4420 heap_region_iterate(&cl); 4421 4422 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4423 4424 G1HRPrinter* hrp = hr_printer(); 4425 if (hrp->is_active()) { 4426 FreeRegionListIterator iter(&local_cleanup_list); 4427 while (iter.more_available()) { 4428 HeapRegion* hr = iter.get_next(); 4429 hrp->cleanup(hr); 4430 } 4431 } 4432 4433 prepend_to_freelist(&local_cleanup_list); 4434 decrement_summary_bytes(cl.bytes_freed()); 4435 4436 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4437 cl.humongous_objects_reclaimed()); 4438 } 4439 4440 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4441 public: 4442 virtual bool do_heap_region(HeapRegion* r) { 4443 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4444 G1CollectedHeap::heap()->clear_in_cset(r); 4445 r->set_young_index_in_cset(-1); 4446 return false; 4447 } 4448 }; 4449 4450 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4451 G1AbandonCollectionSetClosure cl; 4452 collection_set->iterate(&cl); 4453 4454 collection_set->clear(); 4455 collection_set->stop_incremental_building(); 4456 } 4457 4458 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4459 return _allocator->is_retained_old_region(hr); 4460 } 4461 4462 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4463 _eden.add(hr); 4464 _g1_policy->set_region_eden(hr); 4465 } 4466 4467 #ifdef ASSERT 4468 4469 class NoYoungRegionsClosure: public HeapRegionClosure { 4470 private: 4471 bool _success; 4472 public: 4473 NoYoungRegionsClosure() : _success(true) { } 4474 bool do_heap_region(HeapRegion* r) { 4475 if (r->is_young()) { 4476 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4477 p2i(r->bottom()), p2i(r->end())); 4478 _success = false; 4479 } 4480 return false; 4481 } 4482 bool success() { return _success; } 4483 }; 4484 4485 bool G1CollectedHeap::check_young_list_empty() { 4486 bool ret = (young_regions_count() == 0); 4487 4488 NoYoungRegionsClosure closure; 4489 heap_region_iterate(&closure); 4490 ret = ret && closure.success(); 4491 4492 return ret; 4493 } 4494 4495 #endif // ASSERT 4496 4497 class TearDownRegionSetsClosure : public HeapRegionClosure { 4498 HeapRegionSet *_old_set; 4499 4500 public: 4501 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4502 4503 bool do_heap_region(HeapRegion* r) { 4504 if (r->is_old()) { 4505 _old_set->remove(r); 4506 } else if(r->is_young()) { 4507 r->uninstall_surv_rate_group(); 4508 } else { 4509 // We ignore free regions, we'll empty the free list afterwards. 4510 // We ignore humongous and archive regions, we're not tearing down these 4511 // sets. 4512 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4513 "it cannot be another type"); 4514 } 4515 return false; 4516 } 4517 4518 ~TearDownRegionSetsClosure() { 4519 assert(_old_set->is_empty(), "post-condition"); 4520 } 4521 }; 4522 4523 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4524 assert_at_safepoint_on_vm_thread(); 4525 4526 if (!free_list_only) { 4527 TearDownRegionSetsClosure cl(&_old_set); 4528 heap_region_iterate(&cl); 4529 4530 // Note that emptying the _young_list is postponed and instead done as 4531 // the first step when rebuilding the regions sets again. The reason for 4532 // this is that during a full GC string deduplication needs to know if 4533 // a collected region was young or old when the full GC was initiated. 4534 } 4535 _hrm->remove_all_free_regions(); 4536 } 4537 4538 void G1CollectedHeap::increase_used(size_t bytes) { 4539 _summary_bytes_used += bytes; 4540 } 4541 4542 void G1CollectedHeap::decrease_used(size_t bytes) { 4543 assert(_summary_bytes_used >= bytes, 4544 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4545 _summary_bytes_used, bytes); 4546 _summary_bytes_used -= bytes; 4547 } 4548 4549 void G1CollectedHeap::set_used(size_t bytes) { 4550 _summary_bytes_used = bytes; 4551 } 4552 4553 class RebuildRegionSetsClosure : public HeapRegionClosure { 4554 private: 4555 bool _free_list_only; 4556 4557 HeapRegionSet* _old_set; 4558 HeapRegionManager* _hrm; 4559 4560 size_t _total_used; 4561 4562 public: 4563 RebuildRegionSetsClosure(bool free_list_only, 4564 HeapRegionSet* old_set, 4565 HeapRegionManager* hrm) : 4566 _free_list_only(free_list_only), 4567 _old_set(old_set), _hrm(hrm), _total_used(0) { 4568 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4569 if (!free_list_only) { 4570 assert(_old_set->is_empty(), "pre-condition"); 4571 } 4572 } 4573 4574 bool do_heap_region(HeapRegion* r) { 4575 if (r->is_empty()) { 4576 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4577 // Add free regions to the free list 4578 r->set_free(); 4579 _hrm->insert_into_free_list(r); 4580 } else if (!_free_list_only) { 4581 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4582 4583 if (r->is_archive() || r->is_humongous()) { 4584 // We ignore archive and humongous regions. We left these sets unchanged. 4585 } else { 4586 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4587 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4588 r->move_to_old(); 4589 _old_set->add(r); 4590 } 4591 _total_used += r->used(); 4592 } 4593 4594 return false; 4595 } 4596 4597 size_t total_used() { 4598 return _total_used; 4599 } 4600 }; 4601 4602 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4603 assert_at_safepoint_on_vm_thread(); 4604 4605 if (!free_list_only) { 4606 _eden.clear(); 4607 _survivor.clear(); 4608 } 4609 4610 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4611 heap_region_iterate(&cl); 4612 4613 if (!free_list_only) { 4614 set_used(cl.total_used()); 4615 if (_archive_allocator != NULL) { 4616 _archive_allocator->clear_used(); 4617 } 4618 } 4619 assert(used() == recalculate_used(), 4620 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4621 used(), recalculate_used()); 4622 } 4623 4624 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4625 HeapRegion* hr = heap_region_containing(p); 4626 return hr->is_in(p); 4627 } 4628 4629 // Methods for the mutator alloc region 4630 4631 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4632 bool force) { 4633 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4634 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4635 if (force || should_allocate) { 4636 HeapRegion* new_alloc_region = new_region(word_size, 4637 HeapRegionType::Eden, 4638 false /* do_expand */); 4639 if (new_alloc_region != NULL) { 4640 set_region_short_lived_locked(new_alloc_region); 4641 _hr_printer.alloc(new_alloc_region, !should_allocate); 4642 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4643 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4644 return new_alloc_region; 4645 } 4646 } 4647 return NULL; 4648 } 4649 4650 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4651 size_t allocated_bytes) { 4652 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4653 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4654 4655 collection_set()->add_eden_region(alloc_region); 4656 increase_used(allocated_bytes); 4657 _hr_printer.retire(alloc_region); 4658 // We update the eden sizes here, when the region is retired, 4659 // instead of when it's allocated, since this is the point that its 4660 // used space has been recorded in _summary_bytes_used. 4661 g1mm()->update_eden_size(); 4662 } 4663 4664 // Methods for the GC alloc regions 4665 4666 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4667 if (dest.is_old()) { 4668 return true; 4669 } else { 4670 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4671 } 4672 } 4673 4674 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4675 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4676 4677 if (!has_more_regions(dest)) { 4678 return NULL; 4679 } 4680 4681 HeapRegionType type; 4682 if (dest.is_young()) { 4683 type = HeapRegionType::Survivor; 4684 } else { 4685 type = HeapRegionType::Old; 4686 } 4687 4688 HeapRegion* new_alloc_region = new_region(word_size, 4689 type, 4690 true /* do_expand */); 4691 4692 if (new_alloc_region != NULL) { 4693 if (type.is_survivor()) { 4694 new_alloc_region->set_survivor(); 4695 _survivor.add(new_alloc_region); 4696 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4697 } else { 4698 new_alloc_region->set_old(); 4699 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4700 } 4701 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4702 _hr_printer.alloc(new_alloc_region); 4703 return new_alloc_region; 4704 } 4705 return NULL; 4706 } 4707 4708 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4709 size_t allocated_bytes, 4710 InCSetState dest) { 4711 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4712 if (dest.is_old()) { 4713 old_set_add(alloc_region); 4714 } 4715 4716 bool const during_im = collector_state()->in_initial_mark_gc(); 4717 if (during_im && allocated_bytes > 0) { 4718 _cm->root_regions()->add(alloc_region); 4719 } 4720 _hr_printer.retire(alloc_region); 4721 } 4722 4723 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4724 bool expanded = false; 4725 uint index = _hrm->find_highest_free(&expanded); 4726 4727 if (index != G1_NO_HRM_INDEX) { 4728 if (expanded) { 4729 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4730 HeapRegion::GrainWords * HeapWordSize); 4731 } 4732 _hrm->allocate_free_regions_starting_at(index, 1); 4733 return region_at(index); 4734 } 4735 return NULL; 4736 } 4737 4738 // Optimized nmethod scanning 4739 4740 class RegisterNMethodOopClosure: public OopClosure { 4741 G1CollectedHeap* _g1h; 4742 nmethod* _nm; 4743 4744 template <class T> void do_oop_work(T* p) { 4745 T heap_oop = RawAccess<>::oop_load(p); 4746 if (!CompressedOops::is_null(heap_oop)) { 4747 oop obj = CompressedOops::decode_not_null(heap_oop); 4748 HeapRegion* hr = _g1h->heap_region_containing(obj); 4749 assert(!hr->is_continues_humongous(), 4750 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4751 " starting at " HR_FORMAT, 4752 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4753 4754 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4755 hr->add_strong_code_root_locked(_nm); 4756 } 4757 } 4758 4759 public: 4760 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4761 _g1h(g1h), _nm(nm) {} 4762 4763 void do_oop(oop* p) { do_oop_work(p); } 4764 void do_oop(narrowOop* p) { do_oop_work(p); } 4765 }; 4766 4767 class UnregisterNMethodOopClosure: public OopClosure { 4768 G1CollectedHeap* _g1h; 4769 nmethod* _nm; 4770 4771 template <class T> void do_oop_work(T* p) { 4772 T heap_oop = RawAccess<>::oop_load(p); 4773 if (!CompressedOops::is_null(heap_oop)) { 4774 oop obj = CompressedOops::decode_not_null(heap_oop); 4775 HeapRegion* hr = _g1h->heap_region_containing(obj); 4776 assert(!hr->is_continues_humongous(), 4777 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4778 " starting at " HR_FORMAT, 4779 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4780 4781 hr->remove_strong_code_root(_nm); 4782 } 4783 } 4784 4785 public: 4786 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4787 _g1h(g1h), _nm(nm) {} 4788 4789 void do_oop(oop* p) { do_oop_work(p); } 4790 void do_oop(narrowOop* p) { do_oop_work(p); } 4791 }; 4792 4793 // Returns true if the reference points to an object that 4794 // can move in an incremental collection. 4795 bool G1CollectedHeap::is_scavengable(oop obj) { 4796 HeapRegion* hr = heap_region_containing(obj); 4797 return !hr->is_pinned(); 4798 } 4799 4800 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4801 guarantee(nm != NULL, "sanity"); 4802 RegisterNMethodOopClosure reg_cl(this, nm); 4803 nm->oops_do(®_cl); 4804 } 4805 4806 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4807 guarantee(nm != NULL, "sanity"); 4808 UnregisterNMethodOopClosure reg_cl(this, nm); 4809 nm->oops_do(®_cl, true); 4810 } 4811 4812 void G1CollectedHeap::purge_code_root_memory() { 4813 double purge_start = os::elapsedTime(); 4814 G1CodeRootSet::purge(); 4815 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4816 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4817 } 4818 4819 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4820 G1CollectedHeap* _g1h; 4821 4822 public: 4823 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4824 _g1h(g1h) {} 4825 4826 void do_code_blob(CodeBlob* cb) { 4827 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4828 if (nm == NULL) { 4829 return; 4830 } 4831 4832 if (ScavengeRootsInCode) { 4833 _g1h->register_nmethod(nm); 4834 } 4835 } 4836 }; 4837 4838 void G1CollectedHeap::rebuild_strong_code_roots() { 4839 RebuildStrongCodeRootClosure blob_cl(this); 4840 CodeCache::blobs_do(&blob_cl); 4841 } 4842 4843 void G1CollectedHeap::initialize_serviceability() { 4844 _g1mm->initialize_serviceability(); 4845 } 4846 4847 MemoryUsage G1CollectedHeap::memory_usage() { 4848 return _g1mm->memory_usage(); 4849 } 4850 4851 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4852 return _g1mm->memory_managers(); 4853 } 4854 4855 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4856 return _g1mm->memory_pools(); 4857 }