1 /* 2 * Copyright (c) 2001, 2018, 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/g1EvacStats.inline.hpp" 41 #include "gc/g1/g1FullCollector.hpp" 42 #include "gc/g1/g1GCPhaseTimes.hpp" 43 #include "gc/g1/g1HeapSizingPolicy.hpp" 44 #include "gc/g1/g1HeapTransition.hpp" 45 #include "gc/g1/g1HeapVerifier.hpp" 46 #include "gc/g1/g1HotCardCache.hpp" 47 #include "gc/g1/g1MemoryPool.hpp" 48 #include "gc/g1/g1OopClosures.inline.hpp" 49 #include "gc/g1/g1ParScanThreadState.inline.hpp" 50 #include "gc/g1/g1Policy.hpp" 51 #include "gc/g1/g1RegionToSpaceMapper.hpp" 52 #include "gc/g1/g1RemSet.hpp" 53 #include "gc/g1/g1RootClosures.hpp" 54 #include "gc/g1/g1RootProcessor.hpp" 55 #include "gc/g1/g1SATBMarkQueueSet.hpp" 56 #include "gc/g1/g1StringDedup.hpp" 57 #include "gc/g1/g1ThreadLocalData.hpp" 58 #include "gc/g1/g1YCTypes.hpp" 59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 60 #include "gc/g1/heapRegion.inline.hpp" 61 #include "gc/g1/heapRegionRemSet.hpp" 62 #include "gc/g1/heapRegionSet.inline.hpp" 63 #include "gc/g1/vm_operations_g1.hpp" 64 #include "gc/shared/adaptiveSizePolicy.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 "logging/log.hpp" 82 #include "memory/allocation.hpp" 83 #include "memory/iterator.hpp" 84 #include "memory/resourceArea.hpp" 85 #include "oops/access.inline.hpp" 86 #include "oops/compressedOops.inline.hpp" 87 #include "oops/oop.inline.hpp" 88 #include "runtime/atomic.hpp" 89 #include "runtime/flags/flagSetting.hpp" 90 #include "runtime/handles.inline.hpp" 91 #include "runtime/init.hpp" 92 #include "runtime/orderAccess.hpp" 93 #include "runtime/threadSMR.hpp" 94 #include "runtime/vmThread.hpp" 95 #include "utilities/align.hpp" 96 #include "utilities/globalDefinitions.hpp" 97 #include "utilities/stack.inline.hpp" 98 99 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 100 101 // INVARIANTS/NOTES 102 // 103 // All allocation activity covered by the G1CollectedHeap interface is 104 // serialized by acquiring the HeapLock. This happens in mem_allocate 105 // and allocate_new_tlab, which are the "entry" points to the 106 // allocation code from the rest of the JVM. (Note that this does not 107 // apply to TLAB allocation, which is not part of this interface: it 108 // is done by clients of this interface.) 109 110 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 111 private: 112 size_t _num_dirtied; 113 G1CollectedHeap* _g1h; 114 G1CardTable* _g1_ct; 115 116 HeapRegion* region_for_card(jbyte* card_ptr) const { 117 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 118 } 119 120 bool will_become_free(HeapRegion* hr) const { 121 // A region will be freed by free_collection_set if the region is in the 122 // collection set and has not had an evacuation failure. 123 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 124 } 125 126 public: 127 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 128 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 129 130 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 131 HeapRegion* hr = region_for_card(card_ptr); 132 133 // Should only dirty cards in regions that won't be freed. 134 if (!will_become_free(hr)) { 135 *card_ptr = G1CardTable::dirty_card_val(); 136 _num_dirtied++; 137 } 138 139 return true; 140 } 141 142 size_t num_dirtied() const { return _num_dirtied; } 143 }; 144 145 146 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 147 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 148 } 149 150 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 151 // The from card cache is not the memory that is actually committed. So we cannot 152 // take advantage of the zero_filled parameter. 153 reset_from_card_cache(start_idx, num_regions); 154 } 155 156 157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 158 MemRegion mr) { 159 return new HeapRegion(hrs_index, bot(), mr); 160 } 161 162 // Private methods. 163 164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 165 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 166 "the only time we use this to allocate a humongous region is " 167 "when we are allocating a single humongous region"); 168 169 HeapRegion* res = _hrm.allocate_free_region(is_old); 170 171 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 172 // Currently, only attempts to allocate GC alloc regions set 173 // do_expand to true. So, we should only reach here during a 174 // safepoint. If this assumption changes we might have to 175 // reconsider the use of _expand_heap_after_alloc_failure. 176 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 177 178 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 179 word_size * HeapWordSize); 180 181 if (expand(word_size * HeapWordSize)) { 182 // Given that expand() succeeded in expanding the heap, and we 183 // always expand the heap by an amount aligned to the heap 184 // region size, the free list should in theory not be empty. 185 // In either case allocate_free_region() will check for NULL. 186 res = _hrm.allocate_free_region(is_old); 187 } else { 188 _expand_heap_after_alloc_failure = false; 189 } 190 } 191 return res; 192 } 193 194 HeapWord* 195 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 196 uint num_regions, 197 size_t word_size) { 198 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 199 assert(is_humongous(word_size), "word_size should be humongous"); 200 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 201 202 // Index of last region in the series. 203 uint last = first + num_regions - 1; 204 205 // We need to initialize the region(s) we just discovered. This is 206 // a bit tricky given that it can happen concurrently with 207 // refinement threads refining cards on these regions and 208 // potentially wanting to refine the BOT as they are scanning 209 // those cards (this can happen shortly after a cleanup; see CR 210 // 6991377). So we have to set up the region(s) carefully and in 211 // a specific order. 212 213 // The word size sum of all the regions we will allocate. 214 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 215 assert(word_size <= word_size_sum, "sanity"); 216 217 // This will be the "starts humongous" region. 218 HeapRegion* first_hr = region_at(first); 219 // The header of the new object will be placed at the bottom of 220 // the first region. 221 HeapWord* new_obj = first_hr->bottom(); 222 // This will be the new top of the new object. 223 HeapWord* obj_top = new_obj + word_size; 224 225 // First, we need to zero the header of the space that we will be 226 // allocating. When we update top further down, some refinement 227 // threads might try to scan the region. By zeroing the header we 228 // ensure that any thread that will try to scan the region will 229 // come across the zero klass word and bail out. 230 // 231 // NOTE: It would not have been correct to have used 232 // CollectedHeap::fill_with_object() and make the space look like 233 // an int array. The thread that is doing the allocation will 234 // later update the object header to a potentially different array 235 // type and, for a very short period of time, the klass and length 236 // fields will be inconsistent. This could cause a refinement 237 // thread to calculate the object size incorrectly. 238 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 239 240 // Next, pad out the unused tail of the last region with filler 241 // objects, for improved usage accounting. 242 // How many words we use for filler objects. 243 size_t word_fill_size = word_size_sum - word_size; 244 245 // How many words memory we "waste" which cannot hold a filler object. 246 size_t words_not_fillable = 0; 247 248 if (word_fill_size >= min_fill_size()) { 249 fill_with_objects(obj_top, word_fill_size); 250 } else if (word_fill_size > 0) { 251 // We have space to fill, but we cannot fit an object there. 252 words_not_fillable = word_fill_size; 253 word_fill_size = 0; 254 } 255 256 // We will set up the first region as "starts humongous". This 257 // will also update the BOT covering all the regions to reflect 258 // that there is a single object that starts at the bottom of the 259 // first region. 260 first_hr->set_starts_humongous(obj_top, word_fill_size); 261 _g1_policy->remset_tracker()->update_at_allocate(first_hr); 262 // Then, if there are any, we will set up the "continues 263 // humongous" regions. 264 HeapRegion* hr = NULL; 265 for (uint i = first + 1; i <= last; ++i) { 266 hr = region_at(i); 267 hr->set_continues_humongous(first_hr); 268 _g1_policy->remset_tracker()->update_at_allocate(hr); 269 } 270 271 // Up to this point no concurrent thread would have been able to 272 // do any scanning on any region in this series. All the top 273 // fields still point to bottom, so the intersection between 274 // [bottom,top] and [card_start,card_end] will be empty. Before we 275 // update the top fields, we'll do a storestore to make sure that 276 // no thread sees the update to top before the zeroing of the 277 // object header and the BOT initialization. 278 OrderAccess::storestore(); 279 280 // Now, we will update the top fields of the "continues humongous" 281 // regions except the last one. 282 for (uint i = first; i < last; ++i) { 283 hr = region_at(i); 284 hr->set_top(hr->end()); 285 } 286 287 hr = region_at(last); 288 // If we cannot fit a filler object, we must set top to the end 289 // of the humongous object, otherwise we cannot iterate the heap 290 // and the BOT will not be complete. 291 hr->set_top(hr->end() - words_not_fillable); 292 293 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 294 "obj_top should be in last region"); 295 296 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 297 298 assert(words_not_fillable == 0 || 299 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 300 "Miscalculation in humongous allocation"); 301 302 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 303 304 for (uint i = first; i <= last; ++i) { 305 hr = region_at(i); 306 _humongous_set.add(hr); 307 _hr_printer.alloc(hr); 308 } 309 310 return new_obj; 311 } 312 313 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 314 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 315 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 316 } 317 318 // If could fit into free regions w/o expansion, try. 319 // Otherwise, if can expand, do so. 320 // Otherwise, if using ex regions might help, try with ex given back. 321 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 322 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 323 324 _verifier->verify_region_sets_optional(); 325 326 uint first = G1_NO_HRM_INDEX; 327 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 328 329 if (obj_regions == 1) { 330 // Only one region to allocate, try to use a fast path by directly allocating 331 // from the free lists. Do not try to expand here, we will potentially do that 332 // later. 333 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 334 if (hr != NULL) { 335 first = hr->hrm_index(); 336 } 337 } else { 338 // Policy: Try only empty regions (i.e. already committed first). Maybe we 339 // are lucky enough to find some. 340 first = _hrm.find_contiguous_only_empty(obj_regions); 341 if (first != G1_NO_HRM_INDEX) { 342 _hrm.allocate_free_regions_starting_at(first, obj_regions); 343 } 344 } 345 346 if (first == G1_NO_HRM_INDEX) { 347 // Policy: We could not find enough regions for the humongous object in the 348 // free list. Look through the heap to find a mix of free and uncommitted regions. 349 // If so, try expansion. 350 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 351 if (first != G1_NO_HRM_INDEX) { 352 // We found something. Make sure these regions are committed, i.e. expand 353 // the heap. Alternatively we could do a defragmentation GC. 354 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 355 word_size * HeapWordSize); 356 357 _hrm.expand_at(first, obj_regions, workers()); 358 g1_policy()->record_new_heap_size(num_regions()); 359 360 #ifdef ASSERT 361 for (uint i = first; i < first + obj_regions; ++i) { 362 HeapRegion* hr = region_at(i); 363 assert(hr->is_free(), "sanity"); 364 assert(hr->is_empty(), "sanity"); 365 assert(is_on_master_free_list(hr), "sanity"); 366 } 367 #endif 368 _hrm.allocate_free_regions_starting_at(first, obj_regions); 369 } else { 370 // Policy: Potentially trigger a defragmentation GC. 371 } 372 } 373 374 HeapWord* result = NULL; 375 if (first != G1_NO_HRM_INDEX) { 376 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 377 assert(result != NULL, "it should always return a valid result"); 378 379 // A successful humongous object allocation changes the used space 380 // information of the old generation so we need to recalculate the 381 // sizes and update the jstat counters here. 382 g1mm()->update_sizes(); 383 } 384 385 _verifier->verify_region_sets_optional(); 386 387 return result; 388 } 389 390 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size, 391 size_t requested_size, 392 size_t* actual_size) { 393 assert_heap_not_locked_and_not_at_safepoint(); 394 assert(!is_humongous(requested_size), "we do not allow humongous TLABs"); 395 396 return attempt_allocation(min_size, requested_size, actual_size); 397 } 398 399 HeapWord* 400 G1CollectedHeap::mem_allocate(size_t word_size, 401 bool* gc_overhead_limit_was_exceeded) { 402 assert_heap_not_locked_and_not_at_safepoint(); 403 404 if (is_humongous(word_size)) { 405 return attempt_allocation_humongous(word_size); 406 } 407 size_t dummy = 0; 408 return attempt_allocation(word_size, word_size, &dummy); 409 } 410 411 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 412 ResourceMark rm; // For retrieving the thread names in log messages. 413 414 // Make sure you read the note in attempt_allocation_humongous(). 415 416 assert_heap_not_locked_and_not_at_safepoint(); 417 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 418 "be called for humongous allocation requests"); 419 420 // We should only get here after the first-level allocation attempt 421 // (attempt_allocation()) failed to allocate. 422 423 // We will loop until a) we manage to successfully perform the 424 // allocation or b) we successfully schedule a collection which 425 // fails to perform the allocation. b) is the only case when we'll 426 // return NULL. 427 HeapWord* result = NULL; 428 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 429 bool should_try_gc; 430 uint gc_count_before; 431 432 { 433 MutexLockerEx x(Heap_lock); 434 result = _allocator->attempt_allocation_locked(word_size); 435 if (result != NULL) { 436 return result; 437 } 438 439 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 440 // This is different to when only GCLocker::needs_gc() is set: try to avoid 441 // waiting because the GCLocker is active to not wait too long. 442 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 443 // No need for an ergo message here, can_expand_young_list() does this when 444 // it returns true. 445 result = _allocator->attempt_allocation_force(word_size); 446 if (result != NULL) { 447 return result; 448 } 449 } 450 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 451 // the GCLocker initiated GC has been performed and then retry. This includes 452 // the case when the GC Locker is not active but has not been performed. 453 should_try_gc = !GCLocker::needs_gc(); 454 // Read the GC count while still holding the Heap_lock. 455 gc_count_before = total_collections(); 456 } 457 458 if (should_try_gc) { 459 bool succeeded; 460 result = do_collection_pause(word_size, gc_count_before, &succeeded, 461 GCCause::_g1_inc_collection_pause); 462 if (result != NULL) { 463 assert(succeeded, "only way to get back a non-NULL result"); 464 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 465 Thread::current()->name(), p2i(result)); 466 return result; 467 } 468 469 if (succeeded) { 470 // We successfully scheduled a collection which failed to allocate. No 471 // point in trying to allocate further. We'll just return NULL. 472 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 473 SIZE_FORMAT " words", Thread::current()->name(), word_size); 474 return NULL; 475 } 476 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 477 Thread::current()->name(), word_size); 478 } else { 479 // Failed to schedule a collection. 480 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 481 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 482 SIZE_FORMAT " words", Thread::current()->name(), word_size); 483 return NULL; 484 } 485 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 486 // The GCLocker is either active or the GCLocker initiated 487 // GC has not yet been performed. Stall until it is and 488 // then retry the allocation. 489 GCLocker::stall_until_clear(); 490 gclocker_retry_count += 1; 491 } 492 493 // We can reach here if we were unsuccessful in scheduling a 494 // collection (because another thread beat us to it) or if we were 495 // stalled due to the GC locker. In either can we should retry the 496 // allocation attempt in case another thread successfully 497 // performed a collection and reclaimed enough space. We do the 498 // first attempt (without holding the Heap_lock) here and the 499 // follow-on attempt will be at the start of the next loop 500 // iteration (after taking the Heap_lock). 501 size_t dummy = 0; 502 result = _allocator->attempt_allocation(word_size, word_size, &dummy); 503 if (result != NULL) { 504 return result; 505 } 506 507 // Give a warning if we seem to be looping forever. 508 if ((QueuedAllocationWarningCount > 0) && 509 (try_count % QueuedAllocationWarningCount == 0)) { 510 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 511 Thread::current()->name(), try_count, word_size); 512 } 513 } 514 515 ShouldNotReachHere(); 516 return NULL; 517 } 518 519 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 520 assert_at_safepoint_on_vm_thread(); 521 if (_archive_allocator == NULL) { 522 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 523 } 524 } 525 526 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 527 // Allocations in archive regions cannot be of a size that would be considered 528 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 529 // may be different at archive-restore time. 530 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 531 } 532 533 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 534 assert_at_safepoint_on_vm_thread(); 535 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 536 if (is_archive_alloc_too_large(word_size)) { 537 return NULL; 538 } 539 return _archive_allocator->archive_mem_allocate(word_size); 540 } 541 542 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 543 size_t end_alignment_in_bytes) { 544 assert_at_safepoint_on_vm_thread(); 545 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 546 547 // Call complete_archive to do the real work, filling in the MemRegion 548 // array with the archive regions. 549 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 550 delete _archive_allocator; 551 _archive_allocator = NULL; 552 } 553 554 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 555 assert(ranges != NULL, "MemRegion array NULL"); 556 assert(count != 0, "No MemRegions provided"); 557 MemRegion reserved = _hrm.reserved(); 558 for (size_t i = 0; i < count; i++) { 559 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 560 return false; 561 } 562 } 563 return true; 564 } 565 566 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 567 size_t count, 568 bool open) { 569 assert(!is_init_completed(), "Expect to be called at JVM init time"); 570 assert(ranges != NULL, "MemRegion array NULL"); 571 assert(count != 0, "No MemRegions provided"); 572 MutexLockerEx x(Heap_lock); 573 574 MemRegion reserved = _hrm.reserved(); 575 HeapWord* prev_last_addr = NULL; 576 HeapRegion* prev_last_region = NULL; 577 578 // Temporarily disable pretouching of heap pages. This interface is used 579 // when mmap'ing archived heap data in, so pre-touching is wasted. 580 FlagSetting fs(AlwaysPreTouch, false); 581 582 // Enable archive object checking used by G1MarkSweep. We have to let it know 583 // about each archive range, so that objects in those ranges aren't marked. 584 G1ArchiveAllocator::enable_archive_object_check(); 585 586 // For each specified MemRegion range, allocate the corresponding G1 587 // regions and mark them as archive regions. We expect the ranges 588 // in ascending starting address order, without overlap. 589 for (size_t i = 0; i < count; i++) { 590 MemRegion curr_range = ranges[i]; 591 HeapWord* start_address = curr_range.start(); 592 size_t word_size = curr_range.word_size(); 593 HeapWord* last_address = curr_range.last(); 594 size_t commits = 0; 595 596 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 597 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 598 p2i(start_address), p2i(last_address)); 599 guarantee(start_address > prev_last_addr, 600 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 601 p2i(start_address), p2i(prev_last_addr)); 602 prev_last_addr = last_address; 603 604 // Check for ranges that start in the same G1 region in which the previous 605 // range ended, and adjust the start address so we don't try to allocate 606 // the same region again. If the current range is entirely within that 607 // region, skip it, just adjusting the recorded top. 608 HeapRegion* start_region = _hrm.addr_to_region(start_address); 609 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 610 start_address = start_region->end(); 611 if (start_address > last_address) { 612 increase_used(word_size * HeapWordSize); 613 start_region->set_top(last_address + 1); 614 continue; 615 } 616 start_region->set_top(start_address); 617 curr_range = MemRegion(start_address, last_address + 1); 618 start_region = _hrm.addr_to_region(start_address); 619 } 620 621 // Perform the actual region allocation, exiting if it fails. 622 // Then note how much new space we have allocated. 623 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 624 return false; 625 } 626 increase_used(word_size * HeapWordSize); 627 if (commits != 0) { 628 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 629 HeapRegion::GrainWords * HeapWordSize * commits); 630 631 } 632 633 // Mark each G1 region touched by the range as archive, add it to 634 // the old set, and set top. 635 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 636 HeapRegion* last_region = _hrm.addr_to_region(last_address); 637 prev_last_region = last_region; 638 639 while (curr_region != NULL) { 640 assert(curr_region->is_empty() && !curr_region->is_pinned(), 641 "Region already in use (index %u)", curr_region->hrm_index()); 642 if (open) { 643 curr_region->set_open_archive(); 644 } else { 645 curr_region->set_closed_archive(); 646 } 647 _hr_printer.alloc(curr_region); 648 _archive_set.add(curr_region); 649 HeapWord* top; 650 HeapRegion* next_region; 651 if (curr_region != last_region) { 652 top = curr_region->end(); 653 next_region = _hrm.next_region_in_heap(curr_region); 654 } else { 655 top = last_address + 1; 656 next_region = NULL; 657 } 658 curr_region->set_top(top); 659 curr_region->set_first_dead(top); 660 curr_region->set_end_of_live(top); 661 curr_region = next_region; 662 } 663 664 // Notify mark-sweep of the archive 665 G1ArchiveAllocator::set_range_archive(curr_range, open); 666 } 667 return true; 668 } 669 670 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 671 assert(!is_init_completed(), "Expect to be called at JVM init time"); 672 assert(ranges != NULL, "MemRegion array NULL"); 673 assert(count != 0, "No MemRegions provided"); 674 MemRegion reserved = _hrm.reserved(); 675 HeapWord *prev_last_addr = NULL; 676 HeapRegion* prev_last_region = NULL; 677 678 // For each MemRegion, create filler objects, if needed, in the G1 regions 679 // that contain the address range. The address range actually within the 680 // MemRegion will not be modified. That is assumed to have been initialized 681 // elsewhere, probably via an mmap of archived heap data. 682 MutexLockerEx x(Heap_lock); 683 for (size_t i = 0; i < count; i++) { 684 HeapWord* start_address = ranges[i].start(); 685 HeapWord* last_address = ranges[i].last(); 686 687 assert(reserved.contains(start_address) && reserved.contains(last_address), 688 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 689 p2i(start_address), p2i(last_address)); 690 assert(start_address > prev_last_addr, 691 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 692 p2i(start_address), p2i(prev_last_addr)); 693 694 HeapRegion* start_region = _hrm.addr_to_region(start_address); 695 HeapRegion* last_region = _hrm.addr_to_region(last_address); 696 HeapWord* bottom_address = start_region->bottom(); 697 698 // Check for a range beginning in the same region in which the 699 // previous one ended. 700 if (start_region == prev_last_region) { 701 bottom_address = prev_last_addr + 1; 702 } 703 704 // Verify that the regions were all marked as archive regions by 705 // alloc_archive_regions. 706 HeapRegion* curr_region = start_region; 707 while (curr_region != NULL) { 708 guarantee(curr_region->is_archive(), 709 "Expected archive region at index %u", curr_region->hrm_index()); 710 if (curr_region != last_region) { 711 curr_region = _hrm.next_region_in_heap(curr_region); 712 } else { 713 curr_region = NULL; 714 } 715 } 716 717 prev_last_addr = last_address; 718 prev_last_region = last_region; 719 720 // Fill the memory below the allocated range with dummy object(s), 721 // if the region bottom does not match the range start, or if the previous 722 // range ended within the same G1 region, and there is a gap. 723 if (start_address != bottom_address) { 724 size_t fill_size = pointer_delta(start_address, bottom_address); 725 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 726 increase_used(fill_size * HeapWordSize); 727 } 728 } 729 } 730 731 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size, 732 size_t desired_word_size, 733 size_t* actual_word_size) { 734 assert_heap_not_locked_and_not_at_safepoint(); 735 assert(!is_humongous(desired_word_size), "attempt_allocation() should not " 736 "be called for humongous allocation requests"); 737 738 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size); 739 740 if (result == NULL) { 741 *actual_word_size = desired_word_size; 742 result = attempt_allocation_slow(desired_word_size); 743 } 744 745 assert_heap_not_locked(); 746 if (result != NULL) { 747 assert(*actual_word_size != 0, "Actual size must have been set here"); 748 dirty_young_block(result, *actual_word_size); 749 } else { 750 *actual_word_size = 0; 751 } 752 753 return result; 754 } 755 756 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) { 757 assert(!is_init_completed(), "Expect to be called at JVM init time"); 758 assert(ranges != NULL, "MemRegion array NULL"); 759 assert(count != 0, "No MemRegions provided"); 760 MemRegion reserved = _hrm.reserved(); 761 HeapWord* prev_last_addr = NULL; 762 HeapRegion* prev_last_region = NULL; 763 size_t size_used = 0; 764 size_t uncommitted_regions = 0; 765 766 // For each Memregion, free the G1 regions that constitute it, and 767 // notify mark-sweep that the range is no longer to be considered 'archive.' 768 MutexLockerEx x(Heap_lock); 769 for (size_t i = 0; i < count; i++) { 770 HeapWord* start_address = ranges[i].start(); 771 HeapWord* last_address = ranges[i].last(); 772 773 assert(reserved.contains(start_address) && reserved.contains(last_address), 774 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 775 p2i(start_address), p2i(last_address)); 776 assert(start_address > prev_last_addr, 777 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 778 p2i(start_address), p2i(prev_last_addr)); 779 size_used += ranges[i].byte_size(); 780 prev_last_addr = last_address; 781 782 HeapRegion* start_region = _hrm.addr_to_region(start_address); 783 HeapRegion* last_region = _hrm.addr_to_region(last_address); 784 785 // Check for ranges that start in the same G1 region in which the previous 786 // range ended, and adjust the start address so we don't try to free 787 // the same region again. If the current range is entirely within that 788 // region, skip it. 789 if (start_region == prev_last_region) { 790 start_address = start_region->end(); 791 if (start_address > last_address) { 792 continue; 793 } 794 start_region = _hrm.addr_to_region(start_address); 795 } 796 prev_last_region = last_region; 797 798 // After verifying that each region was marked as an archive region by 799 // alloc_archive_regions, set it free and empty and uncommit it. 800 HeapRegion* curr_region = start_region; 801 while (curr_region != NULL) { 802 guarantee(curr_region->is_archive(), 803 "Expected archive region at index %u", curr_region->hrm_index()); 804 uint curr_index = curr_region->hrm_index(); 805 _archive_set.remove(curr_region); 806 curr_region->set_free(); 807 curr_region->set_top(curr_region->bottom()); 808 if (curr_region != last_region) { 809 curr_region = _hrm.next_region_in_heap(curr_region); 810 } else { 811 curr_region = NULL; 812 } 813 _hrm.shrink_at(curr_index, 1); 814 uncommitted_regions++; 815 } 816 817 // Notify mark-sweep that this is no longer an archive range. 818 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open); 819 } 820 821 if (uncommitted_regions != 0) { 822 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 823 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 824 } 825 decrease_used(size_used); 826 } 827 828 oop G1CollectedHeap::materialize_archived_object(oop obj) { 829 assert(obj != NULL, "archived obj is NULL"); 830 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object"); 831 832 // Loading an archived object makes it strongly reachable. If it is 833 // loaded during concurrent marking, it must be enqueued to the SATB 834 // queue, shading the previously white object gray. 835 G1BarrierSet::enqueue(obj); 836 837 return obj; 838 } 839 840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 841 ResourceMark rm; // For retrieving the thread names in log messages. 842 843 // The structure of this method has a lot of similarities to 844 // attempt_allocation_slow(). The reason these two were not merged 845 // into a single one is that such a method would require several "if 846 // allocation is not humongous do this, otherwise do that" 847 // conditional paths which would obscure its flow. In fact, an early 848 // version of this code did use a unified method which was harder to 849 // follow and, as a result, it had subtle bugs that were hard to 850 // track down. So keeping these two methods separate allows each to 851 // be more readable. It will be good to keep these two in sync as 852 // much as possible. 853 854 assert_heap_not_locked_and_not_at_safepoint(); 855 assert(is_humongous(word_size), "attempt_allocation_humongous() " 856 "should only be called for humongous allocations"); 857 858 // Humongous objects can exhaust the heap quickly, so we should check if we 859 // need to start a marking cycle at each humongous object allocation. We do 860 // the check before we do the actual allocation. The reason for doing it 861 // before the allocation is that we avoid having to keep track of the newly 862 // allocated memory while we do a GC. 863 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 864 word_size)) { 865 collect(GCCause::_g1_humongous_allocation); 866 } 867 868 // We will loop until a) we manage to successfully perform the 869 // allocation or b) we successfully schedule a collection which 870 // fails to perform the allocation. b) is the only case when we'll 871 // return NULL. 872 HeapWord* result = NULL; 873 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 874 bool should_try_gc; 875 uint gc_count_before; 876 877 878 { 879 MutexLockerEx x(Heap_lock); 880 881 // Given that humongous objects are not allocated in young 882 // regions, we'll first try to do the allocation without doing a 883 // collection hoping that there's enough space in the heap. 884 result = humongous_obj_allocate(word_size); 885 if (result != NULL) { 886 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 887 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 888 return result; 889 } 890 891 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 892 // the GCLocker initiated GC has been performed and then retry. This includes 893 // the case when the GC Locker is not active but has not been performed. 894 should_try_gc = !GCLocker::needs_gc(); 895 // Read the GC count while still holding the Heap_lock. 896 gc_count_before = total_collections(); 897 } 898 899 if (should_try_gc) { 900 bool succeeded; 901 result = do_collection_pause(word_size, gc_count_before, &succeeded, 902 GCCause::_g1_humongous_allocation); 903 if (result != NULL) { 904 assert(succeeded, "only way to get back a non-NULL result"); 905 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 906 Thread::current()->name(), p2i(result)); 907 return result; 908 } 909 910 if (succeeded) { 911 // We successfully scheduled a collection which failed to allocate. No 912 // point in trying to allocate further. We'll just return NULL. 913 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 914 SIZE_FORMAT " words", Thread::current()->name(), word_size); 915 return NULL; 916 } 917 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 918 Thread::current()->name(), word_size); 919 } else { 920 // Failed to schedule a collection. 921 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 922 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 923 SIZE_FORMAT " words", Thread::current()->name(), word_size); 924 return NULL; 925 } 926 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 927 // The GCLocker is either active or the GCLocker initiated 928 // GC has not yet been performed. Stall until it is and 929 // then retry the allocation. 930 GCLocker::stall_until_clear(); 931 gclocker_retry_count += 1; 932 } 933 934 935 // We can reach here if we were unsuccessful in scheduling a 936 // collection (because another thread beat us to it) or if we were 937 // stalled due to the GC locker. In either can we should retry the 938 // allocation attempt in case another thread successfully 939 // performed a collection and reclaimed enough space. 940 // Humongous object allocation always needs a lock, so we wait for the retry 941 // in the next iteration of the loop, unlike for the regular iteration case. 942 // Give a warning if we seem to be looping forever. 943 944 if ((QueuedAllocationWarningCount > 0) && 945 (try_count % QueuedAllocationWarningCount == 0)) { 946 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 947 Thread::current()->name(), try_count, word_size); 948 } 949 } 950 951 ShouldNotReachHere(); 952 return NULL; 953 } 954 955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 956 bool expect_null_mutator_alloc_region) { 957 assert_at_safepoint_on_vm_thread(); 958 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 959 "the current alloc region was unexpectedly found to be non-NULL"); 960 961 if (!is_humongous(word_size)) { 962 return _allocator->attempt_allocation_locked(word_size); 963 } else { 964 HeapWord* result = humongous_obj_allocate(word_size); 965 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 966 collector_state()->set_initiate_conc_mark_if_possible(true); 967 } 968 return result; 969 } 970 971 ShouldNotReachHere(); 972 } 973 974 class PostCompactionPrinterClosure: public HeapRegionClosure { 975 private: 976 G1HRPrinter* _hr_printer; 977 public: 978 bool do_heap_region(HeapRegion* hr) { 979 assert(!hr->is_young(), "not expecting to find young regions"); 980 _hr_printer->post_compaction(hr); 981 return false; 982 } 983 984 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 985 : _hr_printer(hr_printer) { } 986 }; 987 988 void G1CollectedHeap::print_hrm_post_compaction() { 989 if (_hr_printer.is_active()) { 990 PostCompactionPrinterClosure cl(hr_printer()); 991 heap_region_iterate(&cl); 992 } 993 } 994 995 void G1CollectedHeap::abort_concurrent_cycle() { 996 // If we start the compaction before the CM threads finish 997 // scanning the root regions we might trip them over as we'll 998 // be moving objects / updating references. So let's wait until 999 // they are done. By telling them to abort, they should complete 1000 // early. 1001 _cm->root_regions()->abort(); 1002 _cm->root_regions()->wait_until_scan_finished(); 1003 1004 // Disable discovery and empty the discovered lists 1005 // for the CM ref processor. 1006 _ref_processor_cm->disable_discovery(); 1007 _ref_processor_cm->abandon_partial_discovery(); 1008 _ref_processor_cm->verify_no_references_recorded(); 1009 1010 // Abandon current iterations of concurrent marking and concurrent 1011 // refinement, if any are in progress. 1012 concurrent_mark()->concurrent_cycle_abort(); 1013 } 1014 1015 void G1CollectedHeap::prepare_heap_for_full_collection() { 1016 // Make sure we'll choose a new allocation region afterwards. 1017 _allocator->release_mutator_alloc_region(); 1018 _allocator->abandon_gc_alloc_regions(); 1019 g1_rem_set()->cleanupHRRS(); 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 1030 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1031 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1032 assert(used() == recalculate_used(), "Should be equal"); 1033 _verifier->verify_region_sets_optional(); 1034 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1035 _verifier->check_bitmaps("Full GC Start"); 1036 } 1037 1038 void G1CollectedHeap::prepare_heap_for_mutators() { 1039 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1040 ClassLoaderDataGraph::purge(); 1041 MetaspaceUtils::verify_metrics(); 1042 1043 // Prepare heap for normal collections. 1044 assert(num_free_regions() == 0, "we should not have added any free regions"); 1045 rebuild_region_sets(false /* free_list_only */); 1046 abort_refinement(); 1047 resize_heap_if_necessary(); 1048 1049 // Rebuild the strong code root lists for each region 1050 rebuild_strong_code_roots(); 1051 1052 // Purge code root memory 1053 purge_code_root_memory(); 1054 1055 // Start a new incremental collection set for the next pause 1056 start_new_collection_set(); 1057 1058 _allocator->init_mutator_alloc_region(); 1059 1060 // Post collection state updates. 1061 MetaspaceGC::compute_new_size(); 1062 } 1063 1064 void G1CollectedHeap::abort_refinement() { 1065 if (_hot_card_cache->use_cache()) { 1066 _hot_card_cache->reset_hot_cache(); 1067 } 1068 1069 // Discard all remembered set updates. 1070 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1071 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1072 } 1073 1074 void G1CollectedHeap::verify_after_full_collection() { 1075 _hrm.verify_optional(); 1076 _verifier->verify_region_sets_optional(); 1077 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1078 // Clear the previous marking bitmap, if needed for bitmap verification. 1079 // Note we cannot do this when we clear the next marking bitmap in 1080 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1081 // objects marked during a full GC against the previous bitmap. 1082 // But we need to clear it before calling check_bitmaps below since 1083 // the full GC has compacted objects and updated TAMS but not updated 1084 // the prev bitmap. 1085 if (G1VerifyBitmaps) { 1086 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification"); 1087 _cm->clear_prev_bitmap(workers()); 1088 } 1089 // This call implicitly verifies that the next bitmap is clear after Full GC. 1090 _verifier->check_bitmaps("Full GC End"); 1091 1092 // At this point there should be no regions in the 1093 // entire heap tagged as young. 1094 assert(check_young_list_empty(), "young list should be empty at this point"); 1095 1096 // Note: since we've just done a full GC, concurrent 1097 // marking is no longer active. Therefore we need not 1098 // re-enable reference discovery for the CM ref processor. 1099 // That will be done at the start of the next marking cycle. 1100 // We also know that the STW processor should no longer 1101 // discover any new references. 1102 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1103 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1104 _ref_processor_stw->verify_no_references_recorded(); 1105 _ref_processor_cm->verify_no_references_recorded(); 1106 } 1107 1108 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1109 // Post collection logging. 1110 // We should do this after we potentially resize the heap so 1111 // that all the COMMIT / UNCOMMIT events are generated before 1112 // the compaction events. 1113 print_hrm_post_compaction(); 1114 heap_transition->print(); 1115 print_heap_after_gc(); 1116 print_heap_regions(); 1117 #ifdef TRACESPINNING 1118 ParallelTaskTerminator::print_termination_counts(); 1119 #endif 1120 } 1121 1122 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1123 bool clear_all_soft_refs) { 1124 assert_at_safepoint_on_vm_thread(); 1125 1126 if (GCLocker::check_active_before_gc()) { 1127 // Full GC was not completed. 1128 return false; 1129 } 1130 1131 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1132 soft_ref_policy()->should_clear_all_soft_refs(); 1133 1134 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1135 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1136 1137 collector.prepare_collection(); 1138 collector.collect(); 1139 collector.complete_collection(); 1140 1141 // Full collection was successfully completed. 1142 return true; 1143 } 1144 1145 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1146 // Currently, there is no facility in the do_full_collection(bool) API to notify 1147 // the caller that the collection did not succeed (e.g., because it was locked 1148 // out by the GC locker). So, right now, we'll ignore the return value. 1149 bool dummy = do_full_collection(true, /* explicit_gc */ 1150 clear_all_soft_refs); 1151 } 1152 1153 void G1CollectedHeap::resize_heap_if_necessary() { 1154 // Capacity, free and used after the GC counted as full regions to 1155 // include the waste in the following calculations. 1156 const size_t capacity_after_gc = capacity(); 1157 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1158 1159 // This is enforced in arguments.cpp. 1160 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1161 "otherwise the code below doesn't make sense"); 1162 1163 // We don't have floating point command-line arguments 1164 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1165 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1166 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1167 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1168 1169 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1170 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1171 1172 // We have to be careful here as these two calculations can overflow 1173 // 32-bit size_t's. 1174 double used_after_gc_d = (double) used_after_gc; 1175 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1176 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1177 1178 // Let's make sure that they are both under the max heap size, which 1179 // by default will make them fit into a size_t. 1180 double desired_capacity_upper_bound = (double) max_heap_size; 1181 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1182 desired_capacity_upper_bound); 1183 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1184 desired_capacity_upper_bound); 1185 1186 // We can now safely turn them into size_t's. 1187 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1188 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1189 1190 // This assert only makes sense here, before we adjust them 1191 // with respect to the min and max heap size. 1192 assert(minimum_desired_capacity <= maximum_desired_capacity, 1193 "minimum_desired_capacity = " SIZE_FORMAT ", " 1194 "maximum_desired_capacity = " SIZE_FORMAT, 1195 minimum_desired_capacity, maximum_desired_capacity); 1196 1197 // Should not be greater than the heap max size. No need to adjust 1198 // it with respect to the heap min size as it's a lower bound (i.e., 1199 // we'll try to make the capacity larger than it, not smaller). 1200 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1201 // Should not be less than the heap min size. No need to adjust it 1202 // with respect to the heap max size as it's an upper bound (i.e., 1203 // we'll try to make the capacity smaller than it, not greater). 1204 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1205 1206 if (capacity_after_gc < minimum_desired_capacity) { 1207 // Don't expand unless it's significant 1208 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1209 1210 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1211 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1212 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1213 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1214 1215 expand(expand_bytes, _workers); 1216 1217 // No expansion, now see if we want to shrink 1218 } else if (capacity_after_gc > maximum_desired_capacity) { 1219 // Capacity too large, compute shrinking size 1220 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1221 1222 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1223 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1224 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1225 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1226 1227 shrink(shrink_bytes); 1228 } 1229 } 1230 1231 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1232 bool do_gc, 1233 bool clear_all_soft_refs, 1234 bool expect_null_mutator_alloc_region, 1235 bool* gc_succeeded) { 1236 *gc_succeeded = true; 1237 // Let's attempt the allocation first. 1238 HeapWord* result = 1239 attempt_allocation_at_safepoint(word_size, 1240 expect_null_mutator_alloc_region); 1241 if (result != NULL) { 1242 return result; 1243 } 1244 1245 // In a G1 heap, we're supposed to keep allocation from failing by 1246 // incremental pauses. Therefore, at least for now, we'll favor 1247 // expansion over collection. (This might change in the future if we can 1248 // do something smarter than full collection to satisfy a failed alloc.) 1249 result = expand_and_allocate(word_size); 1250 if (result != NULL) { 1251 return result; 1252 } 1253 1254 if (do_gc) { 1255 // Expansion didn't work, we'll try to do a Full GC. 1256 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1257 clear_all_soft_refs); 1258 } 1259 1260 return NULL; 1261 } 1262 1263 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1264 bool* succeeded) { 1265 assert_at_safepoint_on_vm_thread(); 1266 1267 // Attempts to allocate followed by Full GC. 1268 HeapWord* result = 1269 satisfy_failed_allocation_helper(word_size, 1270 true, /* do_gc */ 1271 false, /* clear_all_soft_refs */ 1272 false, /* expect_null_mutator_alloc_region */ 1273 succeeded); 1274 1275 if (result != NULL || !*succeeded) { 1276 return result; 1277 } 1278 1279 // Attempts to allocate followed by Full GC that will collect all soft references. 1280 result = satisfy_failed_allocation_helper(word_size, 1281 true, /* do_gc */ 1282 true, /* clear_all_soft_refs */ 1283 true, /* expect_null_mutator_alloc_region */ 1284 succeeded); 1285 1286 if (result != NULL || !*succeeded) { 1287 return result; 1288 } 1289 1290 // Attempts to allocate, no GC 1291 result = satisfy_failed_allocation_helper(word_size, 1292 false, /* do_gc */ 1293 false, /* clear_all_soft_refs */ 1294 true, /* expect_null_mutator_alloc_region */ 1295 succeeded); 1296 1297 if (result != NULL) { 1298 return result; 1299 } 1300 1301 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1302 "Flag should have been handled and cleared prior to this point"); 1303 1304 // What else? We might try synchronous finalization later. If the total 1305 // space available is large enough for the allocation, then a more 1306 // complete compaction phase than we've tried so far might be 1307 // appropriate. 1308 return NULL; 1309 } 1310 1311 // Attempting to expand the heap sufficiently 1312 // to support an allocation of the given "word_size". If 1313 // successful, perform the allocation and return the address of the 1314 // allocated block, or else "NULL". 1315 1316 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1317 assert_at_safepoint_on_vm_thread(); 1318 1319 _verifier->verify_region_sets_optional(); 1320 1321 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1322 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1323 word_size * HeapWordSize); 1324 1325 1326 if (expand(expand_bytes, _workers)) { 1327 _hrm.verify_optional(); 1328 _verifier->verify_region_sets_optional(); 1329 return attempt_allocation_at_safepoint(word_size, 1330 false /* expect_null_mutator_alloc_region */); 1331 } 1332 return NULL; 1333 } 1334 1335 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1336 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1337 aligned_expand_bytes = align_up(aligned_expand_bytes, 1338 HeapRegion::GrainBytes); 1339 1340 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1341 expand_bytes, aligned_expand_bytes); 1342 1343 if (is_maximal_no_gc()) { 1344 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1345 return false; 1346 } 1347 1348 double expand_heap_start_time_sec = os::elapsedTime(); 1349 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1350 assert(regions_to_expand > 0, "Must expand by at least one region"); 1351 1352 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1353 if (expand_time_ms != NULL) { 1354 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1355 } 1356 1357 if (expanded_by > 0) { 1358 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1359 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1360 g1_policy()->record_new_heap_size(num_regions()); 1361 } else { 1362 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1363 1364 // The expansion of the virtual storage space was unsuccessful. 1365 // Let's see if it was because we ran out of swap. 1366 if (G1ExitOnExpansionFailure && 1367 _hrm.available() >= regions_to_expand) { 1368 // We had head room... 1369 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1370 } 1371 } 1372 return regions_to_expand > 0; 1373 } 1374 1375 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1376 size_t aligned_shrink_bytes = 1377 ReservedSpace::page_align_size_down(shrink_bytes); 1378 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1379 HeapRegion::GrainBytes); 1380 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1381 1382 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1383 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1384 1385 1386 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", 1387 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1388 if (num_regions_removed > 0) { 1389 g1_policy()->record_new_heap_size(num_regions()); 1390 } else { 1391 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1392 } 1393 } 1394 1395 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1396 _verifier->verify_region_sets_optional(); 1397 1398 // We should only reach here at the end of a Full GC or during Remark which 1399 // means we should not not be holding to any GC alloc regions. The method 1400 // below will make sure of that and do any remaining clean up. 1401 _allocator->abandon_gc_alloc_regions(); 1402 1403 // Instead of tearing down / rebuilding the free lists here, we 1404 // could instead use the remove_all_pending() method on free_list to 1405 // remove only the ones that we need to remove. 1406 tear_down_region_sets(true /* free_list_only */); 1407 shrink_helper(shrink_bytes); 1408 rebuild_region_sets(true /* free_list_only */); 1409 1410 _hrm.verify_optional(); 1411 _verifier->verify_region_sets_optional(); 1412 } 1413 1414 class OldRegionSetChecker : public HeapRegionSetChecker { 1415 public: 1416 void check_mt_safety() { 1417 // Master Old Set MT safety protocol: 1418 // (a) If we're at a safepoint, operations on the master old set 1419 // should be invoked: 1420 // - by the VM thread (which will serialize them), or 1421 // - by the GC workers while holding the FreeList_lock, if we're 1422 // at a safepoint for an evacuation pause (this lock is taken 1423 // anyway when an GC alloc region is retired so that a new one 1424 // is allocated from the free list), or 1425 // - by the GC workers while holding the OldSets_lock, if we're at a 1426 // safepoint for a cleanup pause. 1427 // (b) If we're not at a safepoint, operations on the master old set 1428 // should be invoked while holding the Heap_lock. 1429 1430 if (SafepointSynchronize::is_at_safepoint()) { 1431 guarantee(Thread::current()->is_VM_thread() || 1432 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1433 "master old set MT safety protocol at a safepoint"); 1434 } else { 1435 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1436 } 1437 } 1438 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1439 const char* get_description() { return "Old Regions"; } 1440 }; 1441 1442 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1443 public: 1444 void check_mt_safety() { 1445 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1446 "May only change archive regions during initialization or safepoint."); 1447 } 1448 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1449 const char* get_description() { return "Archive Regions"; } 1450 }; 1451 1452 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1453 public: 1454 void check_mt_safety() { 1455 // Humongous Set MT safety protocol: 1456 // (a) If we're at a safepoint, operations on the master humongous 1457 // set should be invoked by either the VM thread (which will 1458 // serialize them) or by the GC workers while holding the 1459 // OldSets_lock. 1460 // (b) If we're not at a safepoint, operations on the master 1461 // humongous set should be invoked while holding the Heap_lock. 1462 1463 if (SafepointSynchronize::is_at_safepoint()) { 1464 guarantee(Thread::current()->is_VM_thread() || 1465 OldSets_lock->owned_by_self(), 1466 "master humongous set MT safety protocol at a safepoint"); 1467 } else { 1468 guarantee(Heap_lock->owned_by_self(), 1469 "master humongous set MT safety protocol outside a safepoint"); 1470 } 1471 } 1472 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1473 const char* get_description() { return "Humongous Regions"; } 1474 }; 1475 1476 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1477 CollectedHeap(), 1478 _young_gen_sampling_thread(NULL), 1479 _workers(NULL), 1480 _collector_policy(collector_policy), 1481 _card_table(NULL), 1482 _soft_ref_policy(), 1483 _old_set("Old Region Set", new OldRegionSetChecker()), 1484 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1485 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1486 _bot(NULL), 1487 _listener(), 1488 _hrm(), 1489 _allocator(NULL), 1490 _verifier(NULL), 1491 _summary_bytes_used(0), 1492 _archive_allocator(NULL), 1493 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1494 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1495 _expand_heap_after_alloc_failure(true), 1496 _g1mm(NULL), 1497 _humongous_reclaim_candidates(), 1498 _has_humongous_reclaim_candidates(false), 1499 _hr_printer(), 1500 _collector_state(), 1501 _old_marking_cycles_started(0), 1502 _old_marking_cycles_completed(0), 1503 _eden(), 1504 _survivor(), 1505 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1506 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1507 _g1_policy(new G1Policy(_gc_timer_stw)), 1508 _heap_sizing_policy(NULL), 1509 _collection_set(this, _g1_policy), 1510 _hot_card_cache(NULL), 1511 _g1_rem_set(NULL), 1512 _dirty_card_queue_set(false), 1513 _cm(NULL), 1514 _cm_thread(NULL), 1515 _cr(NULL), 1516 _task_queues(NULL), 1517 _evacuation_failed(false), 1518 _evacuation_failed_info_array(NULL), 1519 _preserved_marks_set(true /* in_c_heap */), 1520 #ifndef PRODUCT 1521 _evacuation_failure_alot_for_current_gc(false), 1522 _evacuation_failure_alot_gc_number(0), 1523 _evacuation_failure_alot_count(0), 1524 #endif 1525 _ref_processor_stw(NULL), 1526 _is_alive_closure_stw(this), 1527 _is_subject_to_discovery_stw(this), 1528 _ref_processor_cm(NULL), 1529 _is_alive_closure_cm(this), 1530 _is_subject_to_discovery_cm(this), 1531 _in_cset_fast_test() { 1532 1533 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1534 true /* are_GC_task_threads */, 1535 false /* are_ConcurrentGC_threads */); 1536 _workers->initialize_workers(); 1537 _verifier = new G1HeapVerifier(this); 1538 1539 _allocator = new G1Allocator(this); 1540 1541 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1542 1543 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1544 1545 // Override the default _filler_array_max_size so that no humongous filler 1546 // objects are created. 1547 _filler_array_max_size = _humongous_object_threshold_in_words; 1548 1549 uint n_queues = ParallelGCThreads; 1550 _task_queues = new RefToScanQueueSet(n_queues); 1551 1552 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1553 1554 for (uint i = 0; i < n_queues; i++) { 1555 RefToScanQueue* q = new RefToScanQueue(); 1556 q->initialize(); 1557 _task_queues->register_queue(i, q); 1558 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1559 } 1560 1561 // Initialize the G1EvacuationFailureALot counters and flags. 1562 NOT_PRODUCT(reset_evacuation_should_fail();) 1563 1564 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1565 } 1566 1567 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1568 size_t size, 1569 size_t translation_factor) { 1570 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1571 // Allocate a new reserved space, preferring to use large pages. 1572 ReservedSpace rs(size, preferred_page_size); 1573 G1RegionToSpaceMapper* result = 1574 G1RegionToSpaceMapper::create_mapper(rs, 1575 size, 1576 rs.alignment(), 1577 HeapRegion::GrainBytes, 1578 translation_factor, 1579 mtGC); 1580 1581 os::trace_page_sizes_for_requested_size(description, 1582 size, 1583 preferred_page_size, 1584 rs.alignment(), 1585 rs.base(), 1586 rs.size()); 1587 1588 return result; 1589 } 1590 1591 jint G1CollectedHeap::initialize_concurrent_refinement() { 1592 jint ecode = JNI_OK; 1593 _cr = G1ConcurrentRefine::create(&ecode); 1594 return ecode; 1595 } 1596 1597 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1598 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1599 if (_young_gen_sampling_thread->osthread() == NULL) { 1600 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1601 return JNI_ENOMEM; 1602 } 1603 return JNI_OK; 1604 } 1605 1606 jint G1CollectedHeap::initialize() { 1607 os::enable_vtime(); 1608 1609 // Necessary to satisfy locking discipline assertions. 1610 1611 MutexLocker x(Heap_lock); 1612 1613 // While there are no constraints in the GC code that HeapWordSize 1614 // be any particular value, there are multiple other areas in the 1615 // system which believe this to be true (e.g. oop->object_size in some 1616 // cases incorrectly returns the size in wordSize units rather than 1617 // HeapWordSize). 1618 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1619 1620 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1621 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1622 size_t heap_alignment = collector_policy()->heap_alignment(); 1623 1624 // Ensure that the sizes are properly aligned. 1625 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1626 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1627 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1628 1629 // Reserve the maximum. 1630 1631 // When compressed oops are enabled, the preferred heap base 1632 // is calculated by subtracting the requested size from the 1633 // 32Gb boundary and using the result as the base address for 1634 // heap reservation. If the requested size is not aligned to 1635 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1636 // into the ReservedHeapSpace constructor) then the actual 1637 // base of the reserved heap may end up differing from the 1638 // address that was requested (i.e. the preferred heap base). 1639 // If this happens then we could end up using a non-optimal 1640 // compressed oops mode. 1641 1642 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1643 heap_alignment); 1644 1645 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1646 1647 // Create the barrier set for the entire reserved region. 1648 G1CardTable* ct = new G1CardTable(reserved_region()); 1649 ct->initialize(); 1650 G1BarrierSet* bs = new G1BarrierSet(ct); 1651 bs->initialize(); 1652 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1653 BarrierSet::set_barrier_set(bs); 1654 _card_table = ct; 1655 1656 G1BarrierSet::satb_mark_queue_set().initialize(this, 1657 SATB_Q_CBL_mon, 1658 &bs->satb_mark_queue_buffer_allocator(), 1659 G1SATBProcessCompletedThreshold, 1660 G1SATBBufferEnqueueingThresholdPercent, 1661 Shared_SATB_Q_lock); 1662 1663 // process_completed_threshold and max_completed_queue are updated 1664 // later, based on the concurrent refinement object. 1665 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1666 &bs->dirty_card_queue_buffer_allocator(), 1667 -1, // temp. never trigger 1668 -1, // temp. no limit 1669 Shared_DirtyCardQ_lock, 1670 true); // init_free_ids 1671 1672 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1673 &bs->dirty_card_queue_buffer_allocator(), 1674 -1, // never trigger processing 1675 -1, // no limit on length 1676 Shared_DirtyCardQ_lock); 1677 1678 // Create the hot card cache. 1679 _hot_card_cache = new G1HotCardCache(this); 1680 1681 // Carve out the G1 part of the heap. 1682 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1683 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1684 G1RegionToSpaceMapper* heap_storage = 1685 G1RegionToSpaceMapper::create_mapper(g1_rs, 1686 g1_rs.size(), 1687 page_size, 1688 HeapRegion::GrainBytes, 1689 1, 1690 mtJavaHeap); 1691 os::trace_page_sizes("Heap", 1692 collector_policy()->min_heap_byte_size(), 1693 max_byte_size, 1694 page_size, 1695 heap_rs.base(), 1696 heap_rs.size()); 1697 heap_storage->set_mapping_changed_listener(&_listener); 1698 1699 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1700 G1RegionToSpaceMapper* bot_storage = 1701 create_aux_memory_mapper("Block Offset Table", 1702 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1703 G1BlockOffsetTable::heap_map_factor()); 1704 1705 G1RegionToSpaceMapper* cardtable_storage = 1706 create_aux_memory_mapper("Card Table", 1707 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1708 G1CardTable::heap_map_factor()); 1709 1710 G1RegionToSpaceMapper* card_counts_storage = 1711 create_aux_memory_mapper("Card Counts Table", 1712 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1713 G1CardCounts::heap_map_factor()); 1714 1715 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1716 G1RegionToSpaceMapper* prev_bitmap_storage = 1717 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1718 G1RegionToSpaceMapper* next_bitmap_storage = 1719 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1720 1721 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1722 _card_table->initialize(cardtable_storage); 1723 // Do later initialization work for concurrent refinement. 1724 _hot_card_cache->initialize(card_counts_storage); 1725 1726 // 6843694 - ensure that the maximum region index can fit 1727 // in the remembered set structures. 1728 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1729 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1730 1731 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1732 // start within the first card. 1733 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1734 // Also create a G1 rem set. 1735 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1736 _g1_rem_set->initialize(max_capacity(), max_regions()); 1737 1738 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1739 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1740 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1741 "too many cards per region"); 1742 1743 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1744 1745 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1746 1747 { 1748 HeapWord* start = _hrm.reserved().start(); 1749 HeapWord* end = _hrm.reserved().end(); 1750 size_t granularity = HeapRegion::GrainBytes; 1751 1752 _in_cset_fast_test.initialize(start, end, granularity); 1753 _humongous_reclaim_candidates.initialize(start, end, granularity); 1754 } 1755 1756 // Create the G1ConcurrentMark data structure and thread. 1757 // (Must do this late, so that "max_regions" is defined.) 1758 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1759 if (_cm == NULL || !_cm->completed_initialization()) { 1760 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1761 return JNI_ENOMEM; 1762 } 1763 _cm_thread = _cm->cm_thread(); 1764 1765 // Now expand into the initial heap size. 1766 if (!expand(init_byte_size, _workers)) { 1767 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1768 return JNI_ENOMEM; 1769 } 1770 1771 // Perform any initialization actions delegated to the policy. 1772 g1_policy()->init(this, &_collection_set); 1773 1774 jint ecode = initialize_concurrent_refinement(); 1775 if (ecode != JNI_OK) { 1776 return ecode; 1777 } 1778 1779 ecode = initialize_young_gen_sampling_thread(); 1780 if (ecode != JNI_OK) { 1781 return ecode; 1782 } 1783 1784 { 1785 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1786 dcqs.set_process_completed_threshold((int)concurrent_refine()->yellow_zone()); 1787 dcqs.set_max_completed_queue((int)concurrent_refine()->red_zone()); 1788 } 1789 1790 // Here we allocate the dummy HeapRegion that is required by the 1791 // G1AllocRegion class. 1792 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1793 1794 // We'll re-use the same region whether the alloc region will 1795 // require BOT updates or not and, if it doesn't, then a non-young 1796 // region will complain that it cannot support allocations without 1797 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1798 dummy_region->set_eden(); 1799 // Make sure it's full. 1800 dummy_region->set_top(dummy_region->end()); 1801 G1AllocRegion::setup(this, dummy_region); 1802 1803 _allocator->init_mutator_alloc_region(); 1804 1805 // Do create of the monitoring and management support so that 1806 // values in the heap have been properly initialized. 1807 _g1mm = new G1MonitoringSupport(this); 1808 1809 G1StringDedup::initialize(); 1810 1811 _preserved_marks_set.init(ParallelGCThreads); 1812 1813 _collection_set.initialize(max_regions()); 1814 1815 return JNI_OK; 1816 } 1817 1818 void G1CollectedHeap::stop() { 1819 // Stop all concurrent threads. We do this to make sure these threads 1820 // do not continue to execute and access resources (e.g. logging) 1821 // that are destroyed during shutdown. 1822 _cr->stop(); 1823 _young_gen_sampling_thread->stop(); 1824 _cm_thread->stop(); 1825 if (G1StringDedup::is_enabled()) { 1826 G1StringDedup::stop(); 1827 } 1828 } 1829 1830 void G1CollectedHeap::safepoint_synchronize_begin() { 1831 SuspendibleThreadSet::synchronize(); 1832 } 1833 1834 void G1CollectedHeap::safepoint_synchronize_end() { 1835 SuspendibleThreadSet::desynchronize(); 1836 } 1837 1838 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1839 return HeapRegion::max_region_size(); 1840 } 1841 1842 void G1CollectedHeap::post_initialize() { 1843 CollectedHeap::post_initialize(); 1844 ref_processing_init(); 1845 } 1846 1847 void G1CollectedHeap::ref_processing_init() { 1848 // Reference processing in G1 currently works as follows: 1849 // 1850 // * There are two reference processor instances. One is 1851 // used to record and process discovered references 1852 // during concurrent marking; the other is used to 1853 // record and process references during STW pauses 1854 // (both full and incremental). 1855 // * Both ref processors need to 'span' the entire heap as 1856 // the regions in the collection set may be dotted around. 1857 // 1858 // * For the concurrent marking ref processor: 1859 // * Reference discovery is enabled at initial marking. 1860 // * Reference discovery is disabled and the discovered 1861 // references processed etc during remarking. 1862 // * Reference discovery is MT (see below). 1863 // * Reference discovery requires a barrier (see below). 1864 // * Reference processing may or may not be MT 1865 // (depending on the value of ParallelRefProcEnabled 1866 // and ParallelGCThreads). 1867 // * A full GC disables reference discovery by the CM 1868 // ref processor and abandons any entries on it's 1869 // discovered lists. 1870 // 1871 // * For the STW processor: 1872 // * Non MT discovery is enabled at the start of a full GC. 1873 // * Processing and enqueueing during a full GC is non-MT. 1874 // * During a full GC, references are processed after marking. 1875 // 1876 // * Discovery (may or may not be MT) is enabled at the start 1877 // of an incremental evacuation pause. 1878 // * References are processed near the end of a STW evacuation pause. 1879 // * For both types of GC: 1880 // * Discovery is atomic - i.e. not concurrent. 1881 // * Reference discovery will not need a barrier. 1882 1883 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1884 1885 // Concurrent Mark ref processor 1886 _ref_processor_cm = 1887 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1888 mt_processing, // mt processing 1889 ParallelGCThreads, // degree of mt processing 1890 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1891 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1892 false, // Reference discovery is not atomic 1893 &_is_alive_closure_cm, // is alive closure 1894 true); // allow changes to number of processing threads 1895 1896 // STW ref processor 1897 _ref_processor_stw = 1898 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1899 mt_processing, // mt processing 1900 ParallelGCThreads, // degree of mt processing 1901 (ParallelGCThreads > 1), // mt discovery 1902 ParallelGCThreads, // degree of mt discovery 1903 true, // Reference discovery is atomic 1904 &_is_alive_closure_stw, // is alive closure 1905 true); // allow changes to number of processing threads 1906 } 1907 1908 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1909 return _collector_policy; 1910 } 1911 1912 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1913 return &_soft_ref_policy; 1914 } 1915 1916 size_t G1CollectedHeap::capacity() const { 1917 return _hrm.length() * HeapRegion::GrainBytes; 1918 } 1919 1920 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1921 return _hrm.total_free_bytes(); 1922 } 1923 1924 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1925 _hot_card_cache->drain(cl, worker_i); 1926 } 1927 1928 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1929 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1930 size_t n_completed_buffers = 0; 1931 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1932 n_completed_buffers++; 1933 } 1934 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1935 dcqs.clear_n_completed_buffers(); 1936 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1937 } 1938 1939 // Computes the sum of the storage used by the various regions. 1940 size_t G1CollectedHeap::used() const { 1941 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1942 if (_archive_allocator != NULL) { 1943 result += _archive_allocator->used(); 1944 } 1945 return result; 1946 } 1947 1948 size_t G1CollectedHeap::used_unlocked() const { 1949 return _summary_bytes_used; 1950 } 1951 1952 class SumUsedClosure: public HeapRegionClosure { 1953 size_t _used; 1954 public: 1955 SumUsedClosure() : _used(0) {} 1956 bool do_heap_region(HeapRegion* r) { 1957 _used += r->used(); 1958 return false; 1959 } 1960 size_t result() { return _used; } 1961 }; 1962 1963 size_t G1CollectedHeap::recalculate_used() const { 1964 SumUsedClosure blk; 1965 heap_region_iterate(&blk); 1966 return blk.result(); 1967 } 1968 1969 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1970 switch (cause) { 1971 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1972 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1973 case GCCause::_wb_conc_mark: return true; 1974 default : return false; 1975 } 1976 } 1977 1978 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1979 switch (cause) { 1980 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1981 case GCCause::_g1_humongous_allocation: return true; 1982 default: return is_user_requested_concurrent_full_gc(cause); 1983 } 1984 } 1985 1986 #ifndef PRODUCT 1987 void G1CollectedHeap::allocate_dummy_regions() { 1988 // Let's fill up most of the region 1989 size_t word_size = HeapRegion::GrainWords - 1024; 1990 // And as a result the region we'll allocate will be humongous. 1991 guarantee(is_humongous(word_size), "sanity"); 1992 1993 // _filler_array_max_size is set to humongous object threshold 1994 // but temporarily change it to use CollectedHeap::fill_with_object(). 1995 SizeTFlagSetting fs(_filler_array_max_size, word_size); 1996 1997 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1998 // Let's use the existing mechanism for the allocation 1999 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2000 if (dummy_obj != NULL) { 2001 MemRegion mr(dummy_obj, word_size); 2002 CollectedHeap::fill_with_object(mr); 2003 } else { 2004 // If we can't allocate once, we probably cannot allocate 2005 // again. Let's get out of the loop. 2006 break; 2007 } 2008 } 2009 } 2010 #endif // !PRODUCT 2011 2012 void G1CollectedHeap::increment_old_marking_cycles_started() { 2013 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2014 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2015 "Wrong marking cycle count (started: %d, completed: %d)", 2016 _old_marking_cycles_started, _old_marking_cycles_completed); 2017 2018 _old_marking_cycles_started++; 2019 } 2020 2021 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2022 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2023 2024 // We assume that if concurrent == true, then the caller is a 2025 // concurrent thread that was joined the Suspendible Thread 2026 // Set. If there's ever a cheap way to check this, we should add an 2027 // assert here. 2028 2029 // Given that this method is called at the end of a Full GC or of a 2030 // concurrent cycle, and those can be nested (i.e., a Full GC can 2031 // interrupt a concurrent cycle), the number of full collections 2032 // completed should be either one (in the case where there was no 2033 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2034 // behind the number of full collections started. 2035 2036 // This is the case for the inner caller, i.e. a Full GC. 2037 assert(concurrent || 2038 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2039 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2040 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2041 "is inconsistent with _old_marking_cycles_completed = %u", 2042 _old_marking_cycles_started, _old_marking_cycles_completed); 2043 2044 // This is the case for the outer caller, i.e. the concurrent cycle. 2045 assert(!concurrent || 2046 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2047 "for outer caller (concurrent cycle): " 2048 "_old_marking_cycles_started = %u " 2049 "is inconsistent with _old_marking_cycles_completed = %u", 2050 _old_marking_cycles_started, _old_marking_cycles_completed); 2051 2052 _old_marking_cycles_completed += 1; 2053 2054 // We need to clear the "in_progress" flag in the CM thread before 2055 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2056 // is set) so that if a waiter requests another System.gc() it doesn't 2057 // incorrectly see that a marking cycle is still in progress. 2058 if (concurrent) { 2059 _cm_thread->set_idle(); 2060 } 2061 2062 // This notify_all() will ensure that a thread that called 2063 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2064 // and it's waiting for a full GC to finish will be woken up. It is 2065 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2066 FullGCCount_lock->notify_all(); 2067 } 2068 2069 void G1CollectedHeap::collect(GCCause::Cause cause) { 2070 assert_heap_not_locked(); 2071 2072 uint gc_count_before; 2073 uint old_marking_count_before; 2074 uint full_gc_count_before; 2075 bool retry_gc; 2076 2077 do { 2078 retry_gc = false; 2079 2080 { 2081 MutexLocker ml(Heap_lock); 2082 2083 // Read the GC count while holding the Heap_lock 2084 gc_count_before = total_collections(); 2085 full_gc_count_before = total_full_collections(); 2086 old_marking_count_before = _old_marking_cycles_started; 2087 } 2088 2089 if (should_do_concurrent_full_gc(cause)) { 2090 // Schedule an initial-mark evacuation pause that will start a 2091 // concurrent cycle. We're setting word_size to 0 which means that 2092 // we are not requesting a post-GC allocation. 2093 VM_G1CollectForAllocation op(0, /* word_size */ 2094 gc_count_before, 2095 cause, 2096 true, /* should_initiate_conc_mark */ 2097 g1_policy()->max_pause_time_ms()); 2098 VMThread::execute(&op); 2099 if (!op.pause_succeeded()) { 2100 if (old_marking_count_before == _old_marking_cycles_started) { 2101 retry_gc = op.should_retry_gc(); 2102 } else { 2103 // A Full GC happened while we were trying to schedule the 2104 // initial-mark GC. No point in starting a new cycle given 2105 // that the whole heap was collected anyway. 2106 } 2107 2108 if (retry_gc) { 2109 if (GCLocker::is_active_and_needs_gc()) { 2110 GCLocker::stall_until_clear(); 2111 } 2112 } 2113 } 2114 } else { 2115 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2116 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2117 2118 // Schedule a standard evacuation pause. We're setting word_size 2119 // to 0 which means that we are not requesting a post-GC allocation. 2120 VM_G1CollectForAllocation op(0, /* word_size */ 2121 gc_count_before, 2122 cause, 2123 false, /* should_initiate_conc_mark */ 2124 g1_policy()->max_pause_time_ms()); 2125 VMThread::execute(&op); 2126 } else { 2127 // Schedule a Full GC. 2128 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2129 VMThread::execute(&op); 2130 } 2131 } 2132 } while (retry_gc); 2133 } 2134 2135 bool G1CollectedHeap::is_in(const void* p) const { 2136 if (_hrm.reserved().contains(p)) { 2137 // Given that we know that p is in the reserved space, 2138 // heap_region_containing() should successfully 2139 // return the containing region. 2140 HeapRegion* hr = heap_region_containing(p); 2141 return hr->is_in(p); 2142 } else { 2143 return false; 2144 } 2145 } 2146 2147 #ifdef ASSERT 2148 bool G1CollectedHeap::is_in_exact(const void* p) const { 2149 bool contains = reserved_region().contains(p); 2150 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2151 if (contains && available) { 2152 return true; 2153 } else { 2154 return false; 2155 } 2156 } 2157 #endif 2158 2159 // Iteration functions. 2160 2161 // Iterates an ObjectClosure over all objects within a HeapRegion. 2162 2163 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2164 ObjectClosure* _cl; 2165 public: 2166 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2167 bool do_heap_region(HeapRegion* r) { 2168 if (!r->is_continues_humongous()) { 2169 r->object_iterate(_cl); 2170 } 2171 return false; 2172 } 2173 }; 2174 2175 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2176 IterateObjectClosureRegionClosure blk(cl); 2177 heap_region_iterate(&blk); 2178 } 2179 2180 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2181 _hrm.iterate(cl); 2182 } 2183 2184 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2185 HeapRegionClaimer *hrclaimer, 2186 uint worker_id) const { 2187 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2188 } 2189 2190 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2191 HeapRegionClaimer *hrclaimer) const { 2192 _hrm.par_iterate(cl, hrclaimer, 0); 2193 } 2194 2195 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2196 _collection_set.iterate(cl); 2197 } 2198 2199 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2200 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2201 } 2202 2203 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2204 HeapRegion* hr = heap_region_containing(addr); 2205 return hr->block_start(addr); 2206 } 2207 2208 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2209 HeapRegion* hr = heap_region_containing(addr); 2210 return hr->block_size(addr); 2211 } 2212 2213 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2214 HeapRegion* hr = heap_region_containing(addr); 2215 return hr->block_is_obj(addr); 2216 } 2217 2218 bool G1CollectedHeap::supports_tlab_allocation() const { 2219 return true; 2220 } 2221 2222 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2223 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2224 } 2225 2226 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2227 return _eden.length() * HeapRegion::GrainBytes; 2228 } 2229 2230 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2231 // must be equal to the humongous object limit. 2232 size_t G1CollectedHeap::max_tlab_size() const { 2233 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2234 } 2235 2236 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2237 return _allocator->unsafe_max_tlab_alloc(); 2238 } 2239 2240 size_t G1CollectedHeap::max_capacity() const { 2241 return _hrm.reserved().byte_size(); 2242 } 2243 2244 jlong G1CollectedHeap::millis_since_last_gc() { 2245 // See the notes in GenCollectedHeap::millis_since_last_gc() 2246 // for more information about the implementation. 2247 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2248 _g1_policy->collection_pause_end_millis(); 2249 if (ret_val < 0) { 2250 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2251 ". returning zero instead.", ret_val); 2252 return 0; 2253 } 2254 return ret_val; 2255 } 2256 2257 void G1CollectedHeap::deduplicate_string(oop str) { 2258 assert(java_lang_String::is_instance(str), "invariant"); 2259 2260 if (G1StringDedup::is_enabled()) { 2261 G1StringDedup::deduplicate(str); 2262 } 2263 } 2264 2265 void G1CollectedHeap::prepare_for_verify() { 2266 _verifier->prepare_for_verify(); 2267 } 2268 2269 void G1CollectedHeap::verify(VerifyOption vo) { 2270 _verifier->verify(vo); 2271 } 2272 2273 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2274 return true; 2275 } 2276 2277 const char* const* G1CollectedHeap::concurrent_phases() const { 2278 return _cm_thread->concurrent_phases(); 2279 } 2280 2281 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2282 return _cm_thread->request_concurrent_phase(phase); 2283 } 2284 2285 class PrintRegionClosure: public HeapRegionClosure { 2286 outputStream* _st; 2287 public: 2288 PrintRegionClosure(outputStream* st) : _st(st) {} 2289 bool do_heap_region(HeapRegion* r) { 2290 r->print_on(_st); 2291 return false; 2292 } 2293 }; 2294 2295 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2296 const HeapRegion* hr, 2297 const VerifyOption vo) const { 2298 switch (vo) { 2299 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2300 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2301 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2302 default: ShouldNotReachHere(); 2303 } 2304 return false; // keep some compilers happy 2305 } 2306 2307 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2308 const VerifyOption vo) const { 2309 switch (vo) { 2310 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2311 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2312 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2313 default: ShouldNotReachHere(); 2314 } 2315 return false; // keep some compilers happy 2316 } 2317 2318 void G1CollectedHeap::print_heap_regions() const { 2319 LogTarget(Trace, gc, heap, region) lt; 2320 if (lt.is_enabled()) { 2321 LogStream ls(lt); 2322 print_regions_on(&ls); 2323 } 2324 } 2325 2326 void G1CollectedHeap::print_on(outputStream* st) const { 2327 st->print(" %-20s", "garbage-first heap"); 2328 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2329 capacity()/K, used_unlocked()/K); 2330 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2331 p2i(_hrm.reserved().start()), 2332 p2i(_hrm.reserved().end())); 2333 st->cr(); 2334 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2335 uint young_regions = young_regions_count(); 2336 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2337 (size_t) young_regions * HeapRegion::GrainBytes / K); 2338 uint survivor_regions = survivor_regions_count(); 2339 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2340 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2341 st->cr(); 2342 MetaspaceUtils::print_on(st); 2343 } 2344 2345 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2346 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2347 "HS=humongous(starts), HC=humongous(continues), " 2348 "CS=collection set, F=free, A=archive, " 2349 "TAMS=top-at-mark-start (previous, next)"); 2350 PrintRegionClosure blk(st); 2351 heap_region_iterate(&blk); 2352 } 2353 2354 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2355 print_on(st); 2356 2357 // Print the per-region information. 2358 print_regions_on(st); 2359 } 2360 2361 void G1CollectedHeap::print_on_error(outputStream* st) const { 2362 this->CollectedHeap::print_on_error(st); 2363 2364 if (_cm != NULL) { 2365 st->cr(); 2366 _cm->print_on_error(st); 2367 } 2368 } 2369 2370 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2371 workers()->print_worker_threads_on(st); 2372 _cm_thread->print_on(st); 2373 st->cr(); 2374 _cm->print_worker_threads_on(st); 2375 _cr->print_threads_on(st); 2376 _young_gen_sampling_thread->print_on(st); 2377 if (G1StringDedup::is_enabled()) { 2378 G1StringDedup::print_worker_threads_on(st); 2379 } 2380 } 2381 2382 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2383 workers()->threads_do(tc); 2384 tc->do_thread(_cm_thread); 2385 _cm->threads_do(tc); 2386 _cr->threads_do(tc); 2387 tc->do_thread(_young_gen_sampling_thread); 2388 if (G1StringDedup::is_enabled()) { 2389 G1StringDedup::threads_do(tc); 2390 } 2391 } 2392 2393 void G1CollectedHeap::print_tracing_info() const { 2394 g1_rem_set()->print_summary_info(); 2395 concurrent_mark()->print_summary_info(); 2396 } 2397 2398 #ifndef PRODUCT 2399 // Helpful for debugging RSet issues. 2400 2401 class PrintRSetsClosure : public HeapRegionClosure { 2402 private: 2403 const char* _msg; 2404 size_t _occupied_sum; 2405 2406 public: 2407 bool do_heap_region(HeapRegion* r) { 2408 HeapRegionRemSet* hrrs = r->rem_set(); 2409 size_t occupied = hrrs->occupied(); 2410 _occupied_sum += occupied; 2411 2412 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2413 if (occupied == 0) { 2414 tty->print_cr(" RSet is empty"); 2415 } else { 2416 hrrs->print(); 2417 } 2418 tty->print_cr("----------"); 2419 return false; 2420 } 2421 2422 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2423 tty->cr(); 2424 tty->print_cr("========================================"); 2425 tty->print_cr("%s", msg); 2426 tty->cr(); 2427 } 2428 2429 ~PrintRSetsClosure() { 2430 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2431 tty->print_cr("========================================"); 2432 tty->cr(); 2433 } 2434 }; 2435 2436 void G1CollectedHeap::print_cset_rsets() { 2437 PrintRSetsClosure cl("Printing CSet RSets"); 2438 collection_set_iterate(&cl); 2439 } 2440 2441 void G1CollectedHeap::print_all_rsets() { 2442 PrintRSetsClosure cl("Printing All RSets");; 2443 heap_region_iterate(&cl); 2444 } 2445 #endif // PRODUCT 2446 2447 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2448 2449 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2450 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2451 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2452 2453 size_t eden_capacity_bytes = 2454 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2455 2456 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2457 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2458 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2459 } 2460 2461 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2462 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2463 stats->unused(), stats->used(), stats->region_end_waste(), 2464 stats->regions_filled(), stats->direct_allocated(), 2465 stats->failure_used(), stats->failure_waste()); 2466 } 2467 2468 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2469 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2470 gc_tracer->report_gc_heap_summary(when, heap_summary); 2471 2472 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2473 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2474 } 2475 2476 G1CollectedHeap* G1CollectedHeap::heap() { 2477 CollectedHeap* heap = Universe::heap(); 2478 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2479 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2480 return (G1CollectedHeap*)heap; 2481 } 2482 2483 void G1CollectedHeap::gc_prologue(bool full) { 2484 // always_do_update_barrier = false; 2485 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2486 2487 // This summary needs to be printed before incrementing total collections. 2488 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2489 2490 // Update common counters. 2491 increment_total_collections(full /* full gc */); 2492 if (full) { 2493 increment_old_marking_cycles_started(); 2494 } 2495 2496 // Fill TLAB's and such 2497 double start = os::elapsedTime(); 2498 ensure_parsability(true); 2499 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2500 } 2501 2502 void G1CollectedHeap::gc_epilogue(bool full) { 2503 // Update common counters. 2504 if (full) { 2505 // Update the number of full collections that have been completed. 2506 increment_old_marking_cycles_completed(false /* concurrent */); 2507 } 2508 2509 // We are at the end of the GC. Total collections has already been increased. 2510 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2511 2512 // FIXME: what is this about? 2513 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2514 // is set. 2515 #if COMPILER2_OR_JVMCI 2516 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2517 #endif 2518 // always_do_update_barrier = true; 2519 2520 double start = os::elapsedTime(); 2521 resize_all_tlabs(); 2522 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2523 2524 MemoryService::track_memory_usage(); 2525 // We have just completed a GC. Update the soft reference 2526 // policy with the new heap occupancy 2527 Universe::update_heap_info_at_gc(); 2528 } 2529 2530 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2531 uint gc_count_before, 2532 bool* succeeded, 2533 GCCause::Cause gc_cause) { 2534 assert_heap_not_locked_and_not_at_safepoint(); 2535 VM_G1CollectForAllocation op(word_size, 2536 gc_count_before, 2537 gc_cause, 2538 false, /* should_initiate_conc_mark */ 2539 g1_policy()->max_pause_time_ms()); 2540 VMThread::execute(&op); 2541 2542 HeapWord* result = op.result(); 2543 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2544 assert(result == NULL || ret_succeeded, 2545 "the result should be NULL if the VM did not succeed"); 2546 *succeeded = ret_succeeded; 2547 2548 assert_heap_not_locked(); 2549 return result; 2550 } 2551 2552 void G1CollectedHeap::do_concurrent_mark() { 2553 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2554 if (!_cm_thread->in_progress()) { 2555 _cm_thread->set_started(); 2556 CGC_lock->notify(); 2557 } 2558 } 2559 2560 size_t G1CollectedHeap::pending_card_num() { 2561 size_t extra_cards = 0; 2562 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2563 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2564 extra_cards += dcq.size(); 2565 } 2566 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2567 size_t buffer_size = dcqs.buffer_size(); 2568 size_t buffer_num = dcqs.completed_buffers_num(); 2569 2570 return buffer_size * buffer_num + extra_cards; 2571 } 2572 2573 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2574 // We don't nominate objects with many remembered set entries, on 2575 // the assumption that such objects are likely still live. 2576 HeapRegionRemSet* rem_set = r->rem_set(); 2577 2578 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2579 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2580 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2581 } 2582 2583 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2584 private: 2585 size_t _total_humongous; 2586 size_t _candidate_humongous; 2587 2588 DirtyCardQueue _dcq; 2589 2590 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2591 assert(region->is_starts_humongous(), "Must start a humongous object"); 2592 2593 oop obj = oop(region->bottom()); 2594 2595 // Dead objects cannot be eager reclaim candidates. Due to class 2596 // unloading it is unsafe to query their classes so we return early. 2597 if (g1h->is_obj_dead(obj, region)) { 2598 return false; 2599 } 2600 2601 // If we do not have a complete remembered set for the region, then we can 2602 // not be sure that we have all references to it. 2603 if (!region->rem_set()->is_complete()) { 2604 return false; 2605 } 2606 // Candidate selection must satisfy the following constraints 2607 // while concurrent marking is in progress: 2608 // 2609 // * In order to maintain SATB invariants, an object must not be 2610 // reclaimed if it was allocated before the start of marking and 2611 // has not had its references scanned. Such an object must have 2612 // its references (including type metadata) scanned to ensure no 2613 // live objects are missed by the marking process. Objects 2614 // allocated after the start of concurrent marking don't need to 2615 // be scanned. 2616 // 2617 // * An object must not be reclaimed if it is on the concurrent 2618 // mark stack. Objects allocated after the start of concurrent 2619 // marking are never pushed on the mark stack. 2620 // 2621 // Nominating only objects allocated after the start of concurrent 2622 // marking is sufficient to meet both constraints. This may miss 2623 // some objects that satisfy the constraints, but the marking data 2624 // structures don't support efficiently performing the needed 2625 // additional tests or scrubbing of the mark stack. 2626 // 2627 // However, we presently only nominate is_typeArray() objects. 2628 // A humongous object containing references induces remembered 2629 // set entries on other regions. In order to reclaim such an 2630 // object, those remembered sets would need to be cleaned up. 2631 // 2632 // We also treat is_typeArray() objects specially, allowing them 2633 // to be reclaimed even if allocated before the start of 2634 // concurrent mark. For this we rely on mark stack insertion to 2635 // exclude is_typeArray() objects, preventing reclaiming an object 2636 // that is in the mark stack. We also rely on the metadata for 2637 // such objects to be built-in and so ensured to be kept live. 2638 // Frequent allocation and drop of large binary blobs is an 2639 // important use case for eager reclaim, and this special handling 2640 // may reduce needed headroom. 2641 2642 return obj->is_typeArray() && 2643 g1h->is_potential_eager_reclaim_candidate(region); 2644 } 2645 2646 public: 2647 RegisterHumongousWithInCSetFastTestClosure() 2648 : _total_humongous(0), 2649 _candidate_humongous(0), 2650 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2651 } 2652 2653 virtual bool do_heap_region(HeapRegion* r) { 2654 if (!r->is_starts_humongous()) { 2655 return false; 2656 } 2657 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2658 2659 bool is_candidate = humongous_region_is_candidate(g1h, r); 2660 uint rindex = r->hrm_index(); 2661 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2662 if (is_candidate) { 2663 _candidate_humongous++; 2664 g1h->register_humongous_region_with_cset(rindex); 2665 // Is_candidate already filters out humongous object with large remembered sets. 2666 // If we have a humongous object with a few remembered sets, we simply flush these 2667 // remembered set entries into the DCQS. That will result in automatic 2668 // re-evaluation of their remembered set entries during the following evacuation 2669 // phase. 2670 if (!r->rem_set()->is_empty()) { 2671 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2672 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2673 G1CardTable* ct = g1h->card_table(); 2674 HeapRegionRemSetIterator hrrs(r->rem_set()); 2675 size_t card_index; 2676 while (hrrs.has_next(card_index)) { 2677 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2678 // The remembered set might contain references to already freed 2679 // regions. Filter out such entries to avoid failing card table 2680 // verification. 2681 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2682 if (*card_ptr != G1CardTable::dirty_card_val()) { 2683 *card_ptr = G1CardTable::dirty_card_val(); 2684 _dcq.enqueue(card_ptr); 2685 } 2686 } 2687 } 2688 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2689 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2690 hrrs.n_yielded(), r->rem_set()->occupied()); 2691 // We should only clear the card based remembered set here as we will not 2692 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2693 // (and probably never) we do not enter this path if there are other kind of 2694 // remembered sets for this region. 2695 r->rem_set()->clear_locked(true /* only_cardset */); 2696 // Clear_locked() above sets the state to Empty. However we want to continue 2697 // collecting remembered set entries for humongous regions that were not 2698 // reclaimed. 2699 r->rem_set()->set_state_complete(); 2700 } 2701 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2702 } 2703 _total_humongous++; 2704 2705 return false; 2706 } 2707 2708 size_t total_humongous() const { return _total_humongous; } 2709 size_t candidate_humongous() const { return _candidate_humongous; } 2710 2711 void flush_rem_set_entries() { _dcq.flush(); } 2712 }; 2713 2714 void G1CollectedHeap::register_humongous_regions_with_cset() { 2715 if (!G1EagerReclaimHumongousObjects) { 2716 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2717 return; 2718 } 2719 double time = os::elapsed_counter(); 2720 2721 // Collect reclaim candidate information and register candidates with cset. 2722 RegisterHumongousWithInCSetFastTestClosure cl; 2723 heap_region_iterate(&cl); 2724 2725 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2726 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2727 cl.total_humongous(), 2728 cl.candidate_humongous()); 2729 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2730 2731 // Finally flush all remembered set entries to re-check into the global DCQS. 2732 cl.flush_rem_set_entries(); 2733 } 2734 2735 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2736 public: 2737 bool do_heap_region(HeapRegion* hr) { 2738 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2739 hr->verify_rem_set(); 2740 } 2741 return false; 2742 } 2743 }; 2744 2745 uint G1CollectedHeap::num_task_queues() const { 2746 return _task_queues->size(); 2747 } 2748 2749 #if TASKQUEUE_STATS 2750 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2751 st->print_raw_cr("GC Task Stats"); 2752 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2753 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2754 } 2755 2756 void G1CollectedHeap::print_taskqueue_stats() const { 2757 if (!log_is_enabled(Trace, gc, task, stats)) { 2758 return; 2759 } 2760 Log(gc, task, stats) log; 2761 ResourceMark rm; 2762 LogStream ls(log.trace()); 2763 outputStream* st = &ls; 2764 2765 print_taskqueue_stats_hdr(st); 2766 2767 TaskQueueStats totals; 2768 const uint n = num_task_queues(); 2769 for (uint i = 0; i < n; ++i) { 2770 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2771 totals += task_queue(i)->stats; 2772 } 2773 st->print_raw("tot "); totals.print(st); st->cr(); 2774 2775 DEBUG_ONLY(totals.verify()); 2776 } 2777 2778 void G1CollectedHeap::reset_taskqueue_stats() { 2779 const uint n = num_task_queues(); 2780 for (uint i = 0; i < n; ++i) { 2781 task_queue(i)->stats.reset(); 2782 } 2783 } 2784 #endif // TASKQUEUE_STATS 2785 2786 void G1CollectedHeap::wait_for_root_region_scanning() { 2787 double scan_wait_start = os::elapsedTime(); 2788 // We have to wait until the CM threads finish scanning the 2789 // root regions as it's the only way to ensure that all the 2790 // objects on them have been correctly scanned before we start 2791 // moving them during the GC. 2792 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2793 double wait_time_ms = 0.0; 2794 if (waited) { 2795 double scan_wait_end = os::elapsedTime(); 2796 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2797 } 2798 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2799 } 2800 2801 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2802 private: 2803 G1HRPrinter* _hr_printer; 2804 public: 2805 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2806 2807 virtual bool do_heap_region(HeapRegion* r) { 2808 _hr_printer->cset(r); 2809 return false; 2810 } 2811 }; 2812 2813 void G1CollectedHeap::start_new_collection_set() { 2814 collection_set()->start_incremental_building(); 2815 2816 clear_cset_fast_test(); 2817 2818 guarantee(_eden.length() == 0, "eden should have been cleared"); 2819 g1_policy()->transfer_survivors_to_cset(survivor()); 2820 } 2821 2822 bool 2823 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2824 assert_at_safepoint_on_vm_thread(); 2825 guarantee(!is_gc_active(), "collection is not reentrant"); 2826 2827 if (GCLocker::check_active_before_gc()) { 2828 return false; 2829 } 2830 2831 _gc_timer_stw->register_gc_start(); 2832 2833 GCIdMark gc_id_mark; 2834 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2835 2836 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2837 ResourceMark rm; 2838 2839 g1_policy()->note_gc_start(); 2840 2841 wait_for_root_region_scanning(); 2842 2843 print_heap_before_gc(); 2844 print_heap_regions(); 2845 trace_heap_before_gc(_gc_tracer_stw); 2846 2847 _verifier->verify_region_sets_optional(); 2848 _verifier->verify_dirty_young_regions(); 2849 2850 // We should not be doing initial mark unless the conc mark thread is running 2851 if (!_cm_thread->should_terminate()) { 2852 // This call will decide whether this pause is an initial-mark 2853 // pause. If it is, in_initial_mark_gc() will return true 2854 // for the duration of this pause. 2855 g1_policy()->decide_on_conc_mark_initiation(); 2856 } 2857 2858 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2859 assert(!collector_state()->in_initial_mark_gc() || 2860 collector_state()->in_young_only_phase(), "sanity"); 2861 2862 // We also do not allow mixed GCs during marking. 2863 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2864 2865 // Record whether this pause is an initial mark. When the current 2866 // thread has completed its logging output and it's safe to signal 2867 // the CM thread, the flag's value in the policy has been reset. 2868 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2869 2870 // Inner scope for scope based logging, timers, and stats collection 2871 { 2872 EvacuationInfo evacuation_info; 2873 2874 if (collector_state()->in_initial_mark_gc()) { 2875 // We are about to start a marking cycle, so we increment the 2876 // full collection counter. 2877 increment_old_marking_cycles_started(); 2878 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2879 } 2880 2881 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2882 2883 GCTraceCPUTime tcpu; 2884 2885 G1HeapVerifier::G1VerifyType verify_type; 2886 FormatBuffer<> gc_string("Pause Young "); 2887 if (collector_state()->in_initial_mark_gc()) { 2888 gc_string.append("(Concurrent Start)"); 2889 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2890 } else if (collector_state()->in_young_only_phase()) { 2891 if (collector_state()->in_young_gc_before_mixed()) { 2892 gc_string.append("(Prepare Mixed)"); 2893 } else { 2894 gc_string.append("(Normal)"); 2895 } 2896 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2897 } else { 2898 gc_string.append("(Mixed)"); 2899 verify_type = G1HeapVerifier::G1VerifyMixed; 2900 } 2901 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2902 2903 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2904 workers()->active_workers(), 2905 Threads::number_of_non_daemon_threads()); 2906 active_workers = workers()->update_active_workers(active_workers); 2907 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2908 2909 G1MonitoringScope ms(g1mm(), 2910 false /* full_gc */, 2911 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2912 2913 G1HeapTransition heap_transition(this); 2914 size_t heap_used_bytes_before_gc = used(); 2915 2916 // Don't dynamically change the number of GC threads this early. A value of 2917 // 0 is used to indicate serial work. When parallel work is done, 2918 // it will be set. 2919 2920 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2921 IsGCActiveMark x; 2922 2923 gc_prologue(false); 2924 2925 if (VerifyRememberedSets) { 2926 log_info(gc, verify)("[Verifying RemSets before GC]"); 2927 VerifyRegionRemSetClosure v_cl; 2928 heap_region_iterate(&v_cl); 2929 } 2930 2931 _verifier->verify_before_gc(verify_type); 2932 2933 _verifier->check_bitmaps("GC Start"); 2934 2935 #if COMPILER2_OR_JVMCI 2936 DerivedPointerTable::clear(); 2937 #endif 2938 2939 // Please see comment in g1CollectedHeap.hpp and 2940 // G1CollectedHeap::ref_processing_init() to see how 2941 // reference processing currently works in G1. 2942 2943 // Enable discovery in the STW reference processor 2944 _ref_processor_stw->enable_discovery(); 2945 2946 { 2947 // We want to temporarily turn off discovery by the 2948 // CM ref processor, if necessary, and turn it back on 2949 // on again later if we do. Using a scoped 2950 // NoRefDiscovery object will do this. 2951 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 2952 2953 // Forget the current alloc region (we might even choose it to be part 2954 // of the collection set!). 2955 _allocator->release_mutator_alloc_region(); 2956 2957 // This timing is only used by the ergonomics to handle our pause target. 2958 // It is unclear why this should not include the full pause. We will 2959 // investigate this in CR 7178365. 2960 // 2961 // Preserving the old comment here if that helps the investigation: 2962 // 2963 // The elapsed time induced by the start time below deliberately elides 2964 // the possible verification above. 2965 double sample_start_time_sec = os::elapsedTime(); 2966 2967 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2968 2969 if (collector_state()->in_initial_mark_gc()) { 2970 concurrent_mark()->pre_initial_mark(); 2971 } 2972 2973 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2974 2975 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2976 2977 // Make sure the remembered sets are up to date. This needs to be 2978 // done before register_humongous_regions_with_cset(), because the 2979 // remembered sets are used there to choose eager reclaim candidates. 2980 // If the remembered sets are not up to date we might miss some 2981 // entries that need to be handled. 2982 g1_rem_set()->cleanupHRRS(); 2983 2984 register_humongous_regions_with_cset(); 2985 2986 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 2987 2988 // We call this after finalize_cset() to 2989 // ensure that the CSet has been finalized. 2990 _cm->verify_no_cset_oops(); 2991 2992 if (_hr_printer.is_active()) { 2993 G1PrintCollectionSetClosure cl(&_hr_printer); 2994 _collection_set.iterate(&cl); 2995 } 2996 2997 // Initialize the GC alloc regions. 2998 _allocator->init_gc_alloc_regions(evacuation_info); 2999 3000 G1ParScanThreadStateSet per_thread_states(this, 3001 workers()->active_workers(), 3002 collection_set()->young_region_length(), 3003 collection_set()->optional_region_length()); 3004 pre_evacuate_collection_set(); 3005 3006 // Actually do the work... 3007 evacuate_collection_set(&per_thread_states); 3008 evacuate_optional_collection_set(&per_thread_states); 3009 3010 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3011 3012 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3013 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3014 3015 eagerly_reclaim_humongous_regions(); 3016 3017 record_obj_copy_mem_stats(); 3018 _survivor_evac_stats.adjust_desired_plab_sz(); 3019 _old_evac_stats.adjust_desired_plab_sz(); 3020 3021 double start = os::elapsedTime(); 3022 start_new_collection_set(); 3023 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3024 3025 if (evacuation_failed()) { 3026 double recalculate_used_start = os::elapsedTime(); 3027 set_used(recalculate_used()); 3028 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3029 3030 if (_archive_allocator != NULL) { 3031 _archive_allocator->clear_used(); 3032 } 3033 for (uint i = 0; i < ParallelGCThreads; i++) { 3034 if (_evacuation_failed_info_array[i].has_failed()) { 3035 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3036 } 3037 } 3038 } else { 3039 // The "used" of the the collection set have already been subtracted 3040 // when they were freed. Add in the bytes evacuated. 3041 increase_used(g1_policy()->bytes_copied_during_gc()); 3042 } 3043 3044 if (collector_state()->in_initial_mark_gc()) { 3045 // We have to do this before we notify the CM threads that 3046 // they can start working to make sure that all the 3047 // appropriate initialization is done on the CM object. 3048 concurrent_mark()->post_initial_mark(); 3049 // Note that we don't actually trigger the CM thread at 3050 // this point. We do that later when we're sure that 3051 // the current thread has completed its logging output. 3052 } 3053 3054 allocate_dummy_regions(); 3055 3056 _allocator->init_mutator_alloc_region(); 3057 3058 { 3059 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3060 if (expand_bytes > 0) { 3061 size_t bytes_before = capacity(); 3062 // No need for an ergo logging here, 3063 // expansion_amount() does this when it returns a value > 0. 3064 double expand_ms; 3065 if (!expand(expand_bytes, _workers, &expand_ms)) { 3066 // We failed to expand the heap. Cannot do anything about it. 3067 } 3068 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3069 } 3070 } 3071 3072 // We redo the verification but now wrt to the new CSet which 3073 // has just got initialized after the previous CSet was freed. 3074 _cm->verify_no_cset_oops(); 3075 3076 // This timing is only used by the ergonomics to handle our pause target. 3077 // It is unclear why this should not include the full pause. We will 3078 // investigate this in CR 7178365. 3079 double sample_end_time_sec = os::elapsedTime(); 3080 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3081 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3082 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3083 3084 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3085 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3086 3087 if (VerifyRememberedSets) { 3088 log_info(gc, verify)("[Verifying RemSets after GC]"); 3089 VerifyRegionRemSetClosure v_cl; 3090 heap_region_iterate(&v_cl); 3091 } 3092 3093 _verifier->verify_after_gc(verify_type); 3094 _verifier->check_bitmaps("GC End"); 3095 3096 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3097 _ref_processor_stw->verify_no_references_recorded(); 3098 3099 // CM reference discovery will be re-enabled if necessary. 3100 } 3101 3102 #ifdef TRACESPINNING 3103 ParallelTaskTerminator::print_termination_counts(); 3104 #endif 3105 3106 gc_epilogue(false); 3107 } 3108 3109 // Print the remainder of the GC log output. 3110 if (evacuation_failed()) { 3111 log_info(gc)("To-space exhausted"); 3112 } 3113 3114 g1_policy()->print_phases(); 3115 heap_transition.print(); 3116 3117 // It is not yet to safe to tell the concurrent mark to 3118 // start as we have some optional output below. We don't want the 3119 // output from the concurrent mark thread interfering with this 3120 // logging output either. 3121 3122 _hrm.verify_optional(); 3123 _verifier->verify_region_sets_optional(); 3124 3125 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3126 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3127 3128 print_heap_after_gc(); 3129 print_heap_regions(); 3130 trace_heap_after_gc(_gc_tracer_stw); 3131 3132 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3133 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3134 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3135 // before any GC notifications are raised. 3136 g1mm()->update_sizes(); 3137 3138 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3139 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3140 _gc_timer_stw->register_gc_end(); 3141 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3142 } 3143 // It should now be safe to tell the concurrent mark thread to start 3144 // without its logging output interfering with the logging output 3145 // that came from the pause. 3146 3147 if (should_start_conc_mark) { 3148 // CAUTION: after the doConcurrentMark() call below, 3149 // the concurrent marking thread(s) could be running 3150 // concurrently with us. Make sure that anything after 3151 // this point does not assume that we are the only GC thread 3152 // running. Note: of course, the actual marking work will 3153 // not start until the safepoint itself is released in 3154 // SuspendibleThreadSet::desynchronize(). 3155 do_concurrent_mark(); 3156 } 3157 3158 return true; 3159 } 3160 3161 void G1CollectedHeap::remove_self_forwarding_pointers() { 3162 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3163 workers()->run_task(&rsfp_task); 3164 } 3165 3166 void G1CollectedHeap::restore_after_evac_failure() { 3167 double remove_self_forwards_start = os::elapsedTime(); 3168 3169 remove_self_forwarding_pointers(); 3170 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3171 _preserved_marks_set.restore(&task_executor); 3172 3173 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3174 } 3175 3176 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3177 if (!_evacuation_failed) { 3178 _evacuation_failed = true; 3179 } 3180 3181 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3182 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3183 } 3184 3185 bool G1ParEvacuateFollowersClosure::offer_termination() { 3186 EventGCPhaseParallel event; 3187 G1ParScanThreadState* const pss = par_scan_state(); 3188 start_term_time(); 3189 const bool res = terminator()->offer_termination(); 3190 end_term_time(); 3191 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3192 return res; 3193 } 3194 3195 void G1ParEvacuateFollowersClosure::do_void() { 3196 EventGCPhaseParallel event; 3197 G1ParScanThreadState* const pss = par_scan_state(); 3198 pss->trim_queue(); 3199 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3200 do { 3201 EventGCPhaseParallel event; 3202 pss->steal_and_trim_queue(queues()); 3203 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase)); 3204 } while (!offer_termination()); 3205 } 3206 3207 class G1ParTask : public AbstractGangTask { 3208 protected: 3209 G1CollectedHeap* _g1h; 3210 G1ParScanThreadStateSet* _pss; 3211 RefToScanQueueSet* _queues; 3212 G1RootProcessor* _root_processor; 3213 ParallelTaskTerminator _terminator; 3214 uint _n_workers; 3215 3216 public: 3217 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3218 : AbstractGangTask("G1 collection"), 3219 _g1h(g1h), 3220 _pss(per_thread_states), 3221 _queues(task_queues), 3222 _root_processor(root_processor), 3223 _terminator(n_workers, _queues), 3224 _n_workers(n_workers) 3225 {} 3226 3227 void work(uint worker_id) { 3228 if (worker_id >= _n_workers) return; // no work needed this round 3229 3230 double start_sec = os::elapsedTime(); 3231 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3232 3233 { 3234 ResourceMark rm; 3235 HandleMark hm; 3236 3237 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3238 3239 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3240 pss->set_ref_discoverer(rp); 3241 3242 double start_strong_roots_sec = os::elapsedTime(); 3243 3244 _root_processor->evacuate_roots(pss, worker_id); 3245 3246 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3247 // treating the nmethods visited to act as roots for concurrent marking. 3248 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3249 // objects copied by the current evacuation. 3250 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3251 3252 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3253 3254 double term_sec = 0.0; 3255 size_t evac_term_attempts = 0; 3256 { 3257 double start = os::elapsedTime(); 3258 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::ObjCopy); 3259 evac.do_void(); 3260 3261 evac_term_attempts = evac.term_attempts(); 3262 term_sec = evac.term_time(); 3263 double elapsed_sec = os::elapsedTime() - start; 3264 3265 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3266 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3267 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3268 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3269 } 3270 3271 assert(pss->queue_is_empty(), "should be empty"); 3272 3273 if (log_is_enabled(Debug, gc, task, stats)) { 3274 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3275 size_t lab_waste; 3276 size_t lab_undo_waste; 3277 pss->waste(lab_waste, lab_undo_waste); 3278 _g1h->print_termination_stats(worker_id, 3279 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3280 strong_roots_sec * 1000.0, /* strong roots time */ 3281 term_sec * 1000.0, /* evac term time */ 3282 evac_term_attempts, /* evac term attempts */ 3283 lab_waste, /* alloc buffer waste */ 3284 lab_undo_waste /* undo waste */ 3285 ); 3286 } 3287 3288 // Close the inner scope so that the ResourceMark and HandleMark 3289 // destructors are executed here and are included as part of the 3290 // "GC Worker Time". 3291 } 3292 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3293 } 3294 }; 3295 3296 void G1CollectedHeap::print_termination_stats_hdr() { 3297 log_debug(gc, task, stats)("GC Termination Stats"); 3298 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3299 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3300 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3301 } 3302 3303 void G1CollectedHeap::print_termination_stats(uint worker_id, 3304 double elapsed_ms, 3305 double strong_roots_ms, 3306 double term_ms, 3307 size_t term_attempts, 3308 size_t alloc_buffer_waste, 3309 size_t undo_waste) const { 3310 log_debug(gc, task, stats) 3311 ("%3d %9.2f %9.2f %6.2f " 3312 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3313 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3314 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3315 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3316 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3317 alloc_buffer_waste * HeapWordSize / K, 3318 undo_waste * HeapWordSize / K); 3319 } 3320 3321 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3322 bool class_unloading_occurred) { 3323 uint n_workers = workers()->active_workers(); 3324 3325 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false); 3326 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred); 3327 workers()->run_task(&g1_unlink_task); 3328 } 3329 3330 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3331 bool process_strings, 3332 bool process_string_dedup) { 3333 if (!process_strings && !process_string_dedup) { 3334 // Nothing to clean. 3335 return; 3336 } 3337 3338 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false); 3339 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings); 3340 workers()->run_task(&g1_unlink_task); 3341 } 3342 3343 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3344 private: 3345 DirtyCardQueueSet* _queue; 3346 G1CollectedHeap* _g1h; 3347 public: 3348 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3349 _queue(queue), _g1h(g1h) { } 3350 3351 virtual void work(uint worker_id) { 3352 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3353 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3354 3355 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3356 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3357 3358 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3359 } 3360 }; 3361 3362 void G1CollectedHeap::redirty_logged_cards() { 3363 double redirty_logged_cards_start = os::elapsedTime(); 3364 3365 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3366 dirty_card_queue_set().reset_for_par_iteration(); 3367 workers()->run_task(&redirty_task); 3368 3369 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3370 dcq.merge_bufferlists(&dirty_card_queue_set()); 3371 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3372 3373 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3374 } 3375 3376 // Weak Reference Processing support 3377 3378 bool G1STWIsAliveClosure::do_object_b(oop p) { 3379 // An object is reachable if it is outside the collection set, 3380 // or is inside and copied. 3381 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3382 } 3383 3384 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3385 assert(obj != NULL, "must not be NULL"); 3386 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3387 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3388 // may falsely indicate that this is not the case here: however the collection set only 3389 // contains old regions when concurrent mark is not running. 3390 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3391 } 3392 3393 // Non Copying Keep Alive closure 3394 class G1KeepAliveClosure: public OopClosure { 3395 G1CollectedHeap*_g1h; 3396 public: 3397 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3398 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3399 void do_oop(oop* p) { 3400 oop obj = *p; 3401 assert(obj != NULL, "the caller should have filtered out NULL values"); 3402 3403 const InCSetState cset_state =_g1h->in_cset_state(obj); 3404 if (!cset_state.is_in_cset_or_humongous()) { 3405 return; 3406 } 3407 if (cset_state.is_in_cset()) { 3408 assert( obj->is_forwarded(), "invariant" ); 3409 *p = obj->forwardee(); 3410 } else { 3411 assert(!obj->is_forwarded(), "invariant" ); 3412 assert(cset_state.is_humongous(), 3413 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3414 _g1h->set_humongous_is_live(obj); 3415 } 3416 } 3417 }; 3418 3419 // Copying Keep Alive closure - can be called from both 3420 // serial and parallel code as long as different worker 3421 // threads utilize different G1ParScanThreadState instances 3422 // and different queues. 3423 3424 class G1CopyingKeepAliveClosure: public OopClosure { 3425 G1CollectedHeap* _g1h; 3426 G1ParScanThreadState* _par_scan_state; 3427 3428 public: 3429 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3430 G1ParScanThreadState* pss): 3431 _g1h(g1h), 3432 _par_scan_state(pss) 3433 {} 3434 3435 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3436 virtual void do_oop( oop* p) { do_oop_work(p); } 3437 3438 template <class T> void do_oop_work(T* p) { 3439 oop obj = RawAccess<>::oop_load(p); 3440 3441 if (_g1h->is_in_cset_or_humongous(obj)) { 3442 // If the referent object has been forwarded (either copied 3443 // to a new location or to itself in the event of an 3444 // evacuation failure) then we need to update the reference 3445 // field and, if both reference and referent are in the G1 3446 // heap, update the RSet for the referent. 3447 // 3448 // If the referent has not been forwarded then we have to keep 3449 // it alive by policy. Therefore we have copy the referent. 3450 // 3451 // When the queue is drained (after each phase of reference processing) 3452 // the object and it's followers will be copied, the reference field set 3453 // to point to the new location, and the RSet updated. 3454 _par_scan_state->push_on_queue(p); 3455 } 3456 } 3457 }; 3458 3459 // Serial drain queue closure. Called as the 'complete_gc' 3460 // closure for each discovered list in some of the 3461 // reference processing phases. 3462 3463 class G1STWDrainQueueClosure: public VoidClosure { 3464 protected: 3465 G1CollectedHeap* _g1h; 3466 G1ParScanThreadState* _par_scan_state; 3467 3468 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3469 3470 public: 3471 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3472 _g1h(g1h), 3473 _par_scan_state(pss) 3474 { } 3475 3476 void do_void() { 3477 G1ParScanThreadState* const pss = par_scan_state(); 3478 pss->trim_queue(); 3479 } 3480 }; 3481 3482 // Parallel Reference Processing closures 3483 3484 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3485 // processing during G1 evacuation pauses. 3486 3487 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3488 private: 3489 G1CollectedHeap* _g1h; 3490 G1ParScanThreadStateSet* _pss; 3491 RefToScanQueueSet* _queues; 3492 WorkGang* _workers; 3493 3494 public: 3495 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3496 G1ParScanThreadStateSet* per_thread_states, 3497 WorkGang* workers, 3498 RefToScanQueueSet *task_queues) : 3499 _g1h(g1h), 3500 _pss(per_thread_states), 3501 _queues(task_queues), 3502 _workers(workers) 3503 { 3504 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3505 } 3506 3507 // Executes the given task using concurrent marking worker threads. 3508 virtual void execute(ProcessTask& task, uint ergo_workers); 3509 }; 3510 3511 // Gang task for possibly parallel reference processing 3512 3513 class G1STWRefProcTaskProxy: public AbstractGangTask { 3514 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3515 ProcessTask& _proc_task; 3516 G1CollectedHeap* _g1h; 3517 G1ParScanThreadStateSet* _pss; 3518 RefToScanQueueSet* _task_queues; 3519 ParallelTaskTerminator* _terminator; 3520 3521 public: 3522 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3523 G1CollectedHeap* g1h, 3524 G1ParScanThreadStateSet* per_thread_states, 3525 RefToScanQueueSet *task_queues, 3526 ParallelTaskTerminator* terminator) : 3527 AbstractGangTask("Process reference objects in parallel"), 3528 _proc_task(proc_task), 3529 _g1h(g1h), 3530 _pss(per_thread_states), 3531 _task_queues(task_queues), 3532 _terminator(terminator) 3533 {} 3534 3535 virtual void work(uint worker_id) { 3536 // The reference processing task executed by a single worker. 3537 ResourceMark rm; 3538 HandleMark hm; 3539 3540 G1STWIsAliveClosure is_alive(_g1h); 3541 3542 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3543 pss->set_ref_discoverer(NULL); 3544 3545 // Keep alive closure. 3546 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3547 3548 // Complete GC closure 3549 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy); 3550 3551 // Call the reference processing task's work routine. 3552 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3553 3554 // Note we cannot assert that the refs array is empty here as not all 3555 // of the processing tasks (specifically phase2 - pp2_work) execute 3556 // the complete_gc closure (which ordinarily would drain the queue) so 3557 // the queue may not be empty. 3558 } 3559 }; 3560 3561 // Driver routine for parallel reference processing. 3562 // Creates an instance of the ref processing gang 3563 // task and has the worker threads execute it. 3564 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3565 assert(_workers != NULL, "Need parallel worker threads."); 3566 3567 assert(_workers->active_workers() >= ergo_workers, 3568 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3569 ergo_workers, _workers->active_workers()); 3570 ParallelTaskTerminator terminator(ergo_workers, _queues); 3571 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3572 3573 _workers->run_task(&proc_task_proxy, ergo_workers); 3574 } 3575 3576 // End of weak reference support closures 3577 3578 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3579 double ref_proc_start = os::elapsedTime(); 3580 3581 ReferenceProcessor* rp = _ref_processor_stw; 3582 assert(rp->discovery_enabled(), "should have been enabled"); 3583 3584 // Closure to test whether a referent is alive. 3585 G1STWIsAliveClosure is_alive(this); 3586 3587 // Even when parallel reference processing is enabled, the processing 3588 // of JNI refs is serial and performed serially by the current thread 3589 // rather than by a worker. The following PSS will be used for processing 3590 // JNI refs. 3591 3592 // Use only a single queue for this PSS. 3593 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3594 pss->set_ref_discoverer(NULL); 3595 assert(pss->queue_is_empty(), "pre-condition"); 3596 3597 // Keep alive closure. 3598 G1CopyingKeepAliveClosure keep_alive(this, pss); 3599 3600 // Serial Complete GC closure 3601 G1STWDrainQueueClosure drain_queue(this, pss); 3602 3603 // Setup the soft refs policy... 3604 rp->setup_policy(false); 3605 3606 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3607 3608 ReferenceProcessorStats stats; 3609 if (!rp->processing_is_mt()) { 3610 // Serial reference processing... 3611 stats = rp->process_discovered_references(&is_alive, 3612 &keep_alive, 3613 &drain_queue, 3614 NULL, 3615 pt); 3616 } else { 3617 uint no_of_gc_workers = workers()->active_workers(); 3618 3619 // Parallel reference processing 3620 assert(no_of_gc_workers <= rp->max_num_queues(), 3621 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3622 no_of_gc_workers, rp->max_num_queues()); 3623 3624 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3625 stats = rp->process_discovered_references(&is_alive, 3626 &keep_alive, 3627 &drain_queue, 3628 &par_task_executor, 3629 pt); 3630 } 3631 3632 _gc_tracer_stw->report_gc_reference_stats(stats); 3633 3634 // We have completed copying any necessary live referent objects. 3635 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3636 3637 make_pending_list_reachable(); 3638 3639 rp->verify_no_references_recorded(); 3640 3641 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3642 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3643 } 3644 3645 void G1CollectedHeap::make_pending_list_reachable() { 3646 if (collector_state()->in_initial_mark_gc()) { 3647 oop pll_head = Universe::reference_pending_list(); 3648 if (pll_head != NULL) { 3649 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3650 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3651 } 3652 } 3653 } 3654 3655 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3656 double merge_pss_time_start = os::elapsedTime(); 3657 per_thread_states->flush(); 3658 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3659 } 3660 3661 void G1CollectedHeap::pre_evacuate_collection_set() { 3662 _expand_heap_after_alloc_failure = true; 3663 _evacuation_failed = false; 3664 3665 // Disable the hot card cache. 3666 _hot_card_cache->reset_hot_cache_claimed_index(); 3667 _hot_card_cache->set_use_cache(false); 3668 3669 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3670 _preserved_marks_set.assert_empty(); 3671 3672 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3673 3674 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3675 if (collector_state()->in_initial_mark_gc()) { 3676 double start_clear_claimed_marks = os::elapsedTime(); 3677 3678 ClassLoaderDataGraph::clear_claimed_marks(); 3679 3680 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3681 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3682 } 3683 } 3684 3685 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3686 // Should G1EvacuationFailureALot be in effect for this GC? 3687 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3688 3689 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3690 3691 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3692 3693 double start_par_time_sec = os::elapsedTime(); 3694 double end_par_time_sec; 3695 3696 { 3697 const uint n_workers = workers()->active_workers(); 3698 G1RootProcessor root_processor(this, n_workers); 3699 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3700 3701 print_termination_stats_hdr(); 3702 3703 workers()->run_task(&g1_par_task); 3704 end_par_time_sec = os::elapsedTime(); 3705 3706 // Closing the inner scope will execute the destructor 3707 // for the G1RootProcessor object. We record the current 3708 // elapsed time before closing the scope so that time 3709 // taken for the destructor is NOT included in the 3710 // reported parallel time. 3711 } 3712 3713 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3714 phase_times->record_par_time(par_time_ms); 3715 3716 double code_root_fixup_time_ms = 3717 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3718 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 3719 } 3720 3721 class G1EvacuateOptionalRegionTask : public AbstractGangTask { 3722 G1CollectedHeap* _g1h; 3723 G1ParScanThreadStateSet* _per_thread_states; 3724 G1OptionalCSet* _optional; 3725 RefToScanQueueSet* _queues; 3726 ParallelTaskTerminator _terminator; 3727 3728 Tickspan trim_ticks(G1ParScanThreadState* pss) { 3729 Tickspan copy_time = pss->trim_ticks(); 3730 pss->reset_trim_ticks(); 3731 return copy_time; 3732 } 3733 3734 void scan_roots(G1ParScanThreadState* pss, uint worker_id) { 3735 G1EvacuationRootClosures* root_cls = pss->closures(); 3736 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss); 3737 3738 size_t scanned = 0; 3739 size_t claimed = 0; 3740 size_t skipped = 0; 3741 3742 Ticks start = Ticks::now(); 3743 Tickspan copy_time; 3744 3745 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) { 3746 HeapRegion* hr = _optional->region_at(i); 3747 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl); 3748 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops()); 3749 copy_time += trim_ticks(pss); 3750 3751 G1ScanRSForRegionClosure scan_rs_cl(_g1h->g1_rem_set()->scan_state(), &obj_cl, pss, worker_id); 3752 scan_rs_cl.do_heap_region(hr); 3753 copy_time += trim_ticks(pss); 3754 scanned += scan_rs_cl.cards_scanned(); 3755 claimed += scan_rs_cl.cards_claimed(); 3756 skipped += scan_rs_cl.cards_skipped(); 3757 } 3758 3759 Tickspan scan_time = (Ticks::now() - start) - copy_time; 3760 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3761 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds()); 3762 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds()); 3763 3764 p->record_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards); 3765 p->record_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards); 3766 p->record_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards); 3767 } 3768 3769 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) { 3770 Ticks start = Ticks::now(); 3771 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy); 3772 cl.do_void(); 3773 3774 Tickspan evac_time = (Ticks::now() - start); 3775 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3776 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds()); 3777 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation"); 3778 } 3779 3780 public: 3781 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h, 3782 G1ParScanThreadStateSet* per_thread_states, 3783 G1OptionalCSet* cset, 3784 RefToScanQueueSet* queues, 3785 uint n_workers) : 3786 AbstractGangTask("G1 Evacuation Optional Region Task"), 3787 _g1h(g1h), 3788 _per_thread_states(per_thread_states), 3789 _optional(cset), 3790 _queues(queues), 3791 _terminator(n_workers, _queues) { 3792 } 3793 3794 void work(uint worker_id) { 3795 ResourceMark rm; 3796 HandleMark hm; 3797 3798 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id); 3799 pss->set_ref_discoverer(_g1h->ref_processor_stw()); 3800 3801 scan_roots(pss, worker_id); 3802 evacuate_live_objects(pss, worker_id); 3803 } 3804 }; 3805 3806 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) { 3807 class G1MarkScope : public MarkScope {}; 3808 G1MarkScope code_mark_scope; 3809 3810 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers()); 3811 workers()->run_task(&task); 3812 } 3813 3814 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3815 G1OptionalCSet optional_cset(&_collection_set); 3816 if (optional_cset.is_empty()) { 3817 return; 3818 } 3819 3820 if (evacuation_failed()) { 3821 return; 3822 } 3823 3824 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3825 const double gc_start_time_ms = phase_times->cur_collection_start_sec() * 1000.0; 3826 3827 double start_time_sec = os::elapsedTime(); 3828 3829 do { 3830 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms; 3831 double time_left_ms = MaxGCPauseMillis - time_used_ms; 3832 3833 if (time_left_ms < 0) { 3834 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms); 3835 break; 3836 } 3837 3838 optional_cset.prepare_evacuation(time_left_ms * _g1_policy->optional_evacuation_fraction()); 3839 if (optional_cset.prepare_failed()) { 3840 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms); 3841 break; 3842 } 3843 3844 evacuate_optional_regions(per_thread_states, &optional_cset); 3845 3846 optional_cset.complete_evacuation(); 3847 if (optional_cset.evacuation_failed()) { 3848 break; 3849 } 3850 } while (!optional_cset.is_empty()); 3851 3852 phase_times->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0); 3853 } 3854 3855 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3856 // Also cleans the card table from temporary duplicate detection information used 3857 // during UpdateRS/ScanRS. 3858 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 3859 3860 // Process any discovered reference objects - we have 3861 // to do this _before_ we retire the GC alloc regions 3862 // as we may have to copy some 'reachable' referent 3863 // objects (and their reachable sub-graphs) that were 3864 // not copied during the pause. 3865 process_discovered_references(per_thread_states); 3866 3867 // FIXME 3868 // CM's reference processing also cleans up the string table. 3869 // Should we do that here also? We could, but it is a serial operation 3870 // and could significantly increase the pause time. 3871 3872 G1STWIsAliveClosure is_alive(this); 3873 G1KeepAliveClosure keep_alive(this); 3874 3875 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3876 g1_policy()->phase_times()->weak_phase_times()); 3877 3878 if (G1StringDedup::is_enabled()) { 3879 double fixup_start = os::elapsedTime(); 3880 3881 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 3882 3883 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 3884 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 3885 } 3886 3887 if (evacuation_failed()) { 3888 restore_after_evac_failure(); 3889 3890 // Reset the G1EvacuationFailureALot counters and flags 3891 // Note: the values are reset only when an actual 3892 // evacuation failure occurs. 3893 NOT_PRODUCT(reset_evacuation_should_fail();) 3894 } 3895 3896 _preserved_marks_set.assert_empty(); 3897 3898 _allocator->release_gc_alloc_regions(evacuation_info); 3899 3900 merge_per_thread_state_info(per_thread_states); 3901 3902 // Reset and re-enable the hot card cache. 3903 // Note the counts for the cards in the regions in the 3904 // collection set are reset when the collection set is freed. 3905 _hot_card_cache->reset_hot_cache(); 3906 _hot_card_cache->set_use_cache(true); 3907 3908 purge_code_root_memory(); 3909 3910 redirty_logged_cards(); 3911 #if COMPILER2_OR_JVMCI 3912 double start = os::elapsedTime(); 3913 DerivedPointerTable::update_pointers(); 3914 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3915 #endif 3916 g1_policy()->print_age_table(); 3917 } 3918 3919 void G1CollectedHeap::record_obj_copy_mem_stats() { 3920 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3921 3922 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3923 create_g1_evac_summary(&_old_evac_stats)); 3924 } 3925 3926 void G1CollectedHeap::free_region(HeapRegion* hr, 3927 FreeRegionList* free_list, 3928 bool skip_remset, 3929 bool skip_hot_card_cache, 3930 bool locked) { 3931 assert(!hr->is_free(), "the region should not be free"); 3932 assert(!hr->is_empty(), "the region should not be empty"); 3933 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 3934 assert(free_list != NULL, "pre-condition"); 3935 3936 if (G1VerifyBitmaps) { 3937 MemRegion mr(hr->bottom(), hr->end()); 3938 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3939 } 3940 3941 // Clear the card counts for this region. 3942 // Note: we only need to do this if the region is not young 3943 // (since we don't refine cards in young regions). 3944 if (!skip_hot_card_cache && !hr->is_young()) { 3945 _hot_card_cache->reset_card_counts(hr); 3946 } 3947 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3948 _g1_policy->remset_tracker()->update_at_free(hr); 3949 free_list->add_ordered(hr); 3950 } 3951 3952 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3953 FreeRegionList* free_list) { 3954 assert(hr->is_humongous(), "this is only for humongous regions"); 3955 assert(free_list != NULL, "pre-condition"); 3956 hr->clear_humongous(); 3957 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3958 } 3959 3960 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3961 const uint humongous_regions_removed) { 3962 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3963 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3964 _old_set.bulk_remove(old_regions_removed); 3965 _humongous_set.bulk_remove(humongous_regions_removed); 3966 } 3967 3968 } 3969 3970 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3971 assert(list != NULL, "list can't be null"); 3972 if (!list->is_empty()) { 3973 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3974 _hrm.insert_list_into_free_list(list); 3975 } 3976 } 3977 3978 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3979 decrease_used(bytes); 3980 } 3981 3982 class G1FreeCollectionSetTask : public AbstractGangTask { 3983 private: 3984 3985 // Closure applied to all regions in the collection set to do work that needs to 3986 // be done serially in a single thread. 3987 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3988 private: 3989 EvacuationInfo* _evacuation_info; 3990 const size_t* _surviving_young_words; 3991 3992 // Bytes used in successfully evacuated regions before the evacuation. 3993 size_t _before_used_bytes; 3994 // Bytes used in unsucessfully evacuated regions before the evacuation 3995 size_t _after_used_bytes; 3996 3997 size_t _bytes_allocated_in_old_since_last_gc; 3998 3999 size_t _failure_used_words; 4000 size_t _failure_waste_words; 4001 4002 FreeRegionList _local_free_list; 4003 public: 4004 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4005 HeapRegionClosure(), 4006 _evacuation_info(evacuation_info), 4007 _surviving_young_words(surviving_young_words), 4008 _before_used_bytes(0), 4009 _after_used_bytes(0), 4010 _bytes_allocated_in_old_since_last_gc(0), 4011 _failure_used_words(0), 4012 _failure_waste_words(0), 4013 _local_free_list("Local Region List for CSet Freeing") { 4014 } 4015 4016 virtual bool do_heap_region(HeapRegion* r) { 4017 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4018 4019 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4020 g1h->clear_in_cset(r); 4021 4022 if (r->is_young()) { 4023 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4024 "Young index %d is wrong for region %u of type %s with %u young regions", 4025 r->young_index_in_cset(), 4026 r->hrm_index(), 4027 r->get_type_str(), 4028 g1h->collection_set()->young_region_length()); 4029 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4030 r->record_surv_words_in_group(words_survived); 4031 } 4032 4033 if (!r->evacuation_failed()) { 4034 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4035 _before_used_bytes += r->used(); 4036 g1h->free_region(r, 4037 &_local_free_list, 4038 true, /* skip_remset */ 4039 true, /* skip_hot_card_cache */ 4040 true /* locked */); 4041 } else { 4042 r->uninstall_surv_rate_group(); 4043 r->set_young_index_in_cset(-1); 4044 r->set_evacuation_failed(false); 4045 // When moving a young gen region to old gen, we "allocate" that whole region 4046 // there. This is in addition to any already evacuated objects. Notify the 4047 // policy about that. 4048 // Old gen regions do not cause an additional allocation: both the objects 4049 // still in the region and the ones already moved are accounted for elsewhere. 4050 if (r->is_young()) { 4051 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4052 } 4053 // The region is now considered to be old. 4054 r->set_old(); 4055 // Do some allocation statistics accounting. Regions that failed evacuation 4056 // are always made old, so there is no need to update anything in the young 4057 // gen statistics, but we need to update old gen statistics. 4058 size_t used_words = r->marked_bytes() / HeapWordSize; 4059 4060 _failure_used_words += used_words; 4061 _failure_waste_words += HeapRegion::GrainWords - used_words; 4062 4063 g1h->old_set_add(r); 4064 _after_used_bytes += r->used(); 4065 } 4066 return false; 4067 } 4068 4069 void complete_work() { 4070 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4071 4072 _evacuation_info->set_regions_freed(_local_free_list.length()); 4073 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4074 4075 g1h->prepend_to_freelist(&_local_free_list); 4076 g1h->decrement_summary_bytes(_before_used_bytes); 4077 4078 G1Policy* policy = g1h->g1_policy(); 4079 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4080 4081 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4082 } 4083 }; 4084 4085 G1CollectionSet* _collection_set; 4086 G1SerialFreeCollectionSetClosure _cl; 4087 const size_t* _surviving_young_words; 4088 4089 size_t _rs_lengths; 4090 4091 volatile jint _serial_work_claim; 4092 4093 struct WorkItem { 4094 uint region_idx; 4095 bool is_young; 4096 bool evacuation_failed; 4097 4098 WorkItem(HeapRegion* r) { 4099 region_idx = r->hrm_index(); 4100 is_young = r->is_young(); 4101 evacuation_failed = r->evacuation_failed(); 4102 } 4103 }; 4104 4105 volatile size_t _parallel_work_claim; 4106 size_t _num_work_items; 4107 WorkItem* _work_items; 4108 4109 void do_serial_work() { 4110 // Need to grab the lock to be allowed to modify the old region list. 4111 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4112 _collection_set->iterate(&_cl); 4113 } 4114 4115 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4116 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4117 4118 HeapRegion* r = g1h->region_at(region_idx); 4119 assert(!g1h->is_on_master_free_list(r), "sanity"); 4120 4121 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4122 4123 if (!is_young) { 4124 g1h->_hot_card_cache->reset_card_counts(r); 4125 } 4126 4127 if (!evacuation_failed) { 4128 r->rem_set()->clear_locked(); 4129 } 4130 } 4131 4132 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4133 private: 4134 size_t _cur_idx; 4135 WorkItem* _work_items; 4136 public: 4137 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4138 4139 virtual bool do_heap_region(HeapRegion* r) { 4140 _work_items[_cur_idx++] = WorkItem(r); 4141 return false; 4142 } 4143 }; 4144 4145 void prepare_work() { 4146 G1PrepareFreeCollectionSetClosure cl(_work_items); 4147 _collection_set->iterate(&cl); 4148 } 4149 4150 void complete_work() { 4151 _cl.complete_work(); 4152 4153 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4154 policy->record_max_rs_lengths(_rs_lengths); 4155 policy->cset_regions_freed(); 4156 } 4157 public: 4158 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4159 AbstractGangTask("G1 Free Collection Set"), 4160 _collection_set(collection_set), 4161 _cl(evacuation_info, surviving_young_words), 4162 _surviving_young_words(surviving_young_words), 4163 _rs_lengths(0), 4164 _serial_work_claim(0), 4165 _parallel_work_claim(0), 4166 _num_work_items(collection_set->region_length()), 4167 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4168 prepare_work(); 4169 } 4170 4171 ~G1FreeCollectionSetTask() { 4172 complete_work(); 4173 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4174 } 4175 4176 // Chunk size for work distribution. The chosen value has been determined experimentally 4177 // to be a good tradeoff between overhead and achievable parallelism. 4178 static uint chunk_size() { return 32; } 4179 4180 virtual void work(uint worker_id) { 4181 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4182 4183 // Claim serial work. 4184 if (_serial_work_claim == 0) { 4185 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4186 if (value == 0) { 4187 double serial_time = os::elapsedTime(); 4188 do_serial_work(); 4189 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4190 } 4191 } 4192 4193 // Start parallel work. 4194 double young_time = 0.0; 4195 bool has_young_time = false; 4196 double non_young_time = 0.0; 4197 bool has_non_young_time = false; 4198 4199 while (true) { 4200 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4201 size_t cur = end - chunk_size(); 4202 4203 if (cur >= _num_work_items) { 4204 break; 4205 } 4206 4207 EventGCPhaseParallel event; 4208 double start_time = os::elapsedTime(); 4209 4210 end = MIN2(end, _num_work_items); 4211 4212 for (; cur < end; cur++) { 4213 bool is_young = _work_items[cur].is_young; 4214 4215 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4216 4217 double end_time = os::elapsedTime(); 4218 double time_taken = end_time - start_time; 4219 if (is_young) { 4220 young_time += time_taken; 4221 has_young_time = true; 4222 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4223 } else { 4224 non_young_time += time_taken; 4225 has_non_young_time = true; 4226 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4227 } 4228 start_time = end_time; 4229 } 4230 } 4231 4232 if (has_young_time) { 4233 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4234 } 4235 if (has_non_young_time) { 4236 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4237 } 4238 } 4239 }; 4240 4241 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4242 _eden.clear(); 4243 4244 double free_cset_start_time = os::elapsedTime(); 4245 4246 { 4247 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4248 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4249 4250 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4251 4252 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4253 cl.name(), 4254 num_workers, 4255 _collection_set.region_length()); 4256 workers()->run_task(&cl, num_workers); 4257 } 4258 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4259 4260 collection_set->clear(); 4261 } 4262 4263 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4264 private: 4265 FreeRegionList* _free_region_list; 4266 HeapRegionSet* _proxy_set; 4267 uint _humongous_objects_reclaimed; 4268 uint _humongous_regions_reclaimed; 4269 size_t _freed_bytes; 4270 public: 4271 4272 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4273 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4274 } 4275 4276 virtual bool do_heap_region(HeapRegion* r) { 4277 if (!r->is_starts_humongous()) { 4278 return false; 4279 } 4280 4281 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4282 4283 oop obj = (oop)r->bottom(); 4284 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4285 4286 // The following checks whether the humongous object is live are sufficient. 4287 // The main additional check (in addition to having a reference from the roots 4288 // or the young gen) is whether the humongous object has a remembered set entry. 4289 // 4290 // A humongous object cannot be live if there is no remembered set for it 4291 // because: 4292 // - there can be no references from within humongous starts regions referencing 4293 // the object because we never allocate other objects into them. 4294 // (I.e. there are no intra-region references that may be missed by the 4295 // remembered set) 4296 // - as soon there is a remembered set entry to the humongous starts region 4297 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4298 // until the end of a concurrent mark. 4299 // 4300 // It is not required to check whether the object has been found dead by marking 4301 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4302 // all objects allocated during that time are considered live. 4303 // SATB marking is even more conservative than the remembered set. 4304 // So if at this point in the collection there is no remembered set entry, 4305 // nobody has a reference to it. 4306 // At the start of collection we flush all refinement logs, and remembered sets 4307 // are completely up-to-date wrt to references to the humongous object. 4308 // 4309 // Other implementation considerations: 4310 // - never consider object arrays at this time because they would pose 4311 // considerable effort for cleaning up the the remembered sets. This is 4312 // required because stale remembered sets might reference locations that 4313 // are currently allocated into. 4314 uint region_idx = r->hrm_index(); 4315 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4316 !r->rem_set()->is_empty()) { 4317 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", 4318 region_idx, 4319 (size_t)obj->size() * HeapWordSize, 4320 p2i(r->bottom()), 4321 r->rem_set()->occupied(), 4322 r->rem_set()->strong_code_roots_list_length(), 4323 next_bitmap->is_marked(r->bottom()), 4324 g1h->is_humongous_reclaim_candidate(region_idx), 4325 obj->is_typeArray() 4326 ); 4327 return false; 4328 } 4329 4330 guarantee(obj->is_typeArray(), 4331 "Only eagerly reclaiming type arrays is supported, but the object " 4332 PTR_FORMAT " is not.", p2i(r->bottom())); 4333 4334 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", 4335 region_idx, 4336 (size_t)obj->size() * HeapWordSize, 4337 p2i(r->bottom()), 4338 r->rem_set()->occupied(), 4339 r->rem_set()->strong_code_roots_list_length(), 4340 next_bitmap->is_marked(r->bottom()), 4341 g1h->is_humongous_reclaim_candidate(region_idx), 4342 obj->is_typeArray() 4343 ); 4344 4345 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4346 cm->humongous_object_eagerly_reclaimed(r); 4347 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4348 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4349 region_idx, 4350 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4351 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4352 _humongous_objects_reclaimed++; 4353 do { 4354 HeapRegion* next = g1h->next_region_in_humongous(r); 4355 _freed_bytes += r->used(); 4356 r->set_containing_set(NULL); 4357 _humongous_regions_reclaimed++; 4358 g1h->free_humongous_region(r, _free_region_list); 4359 r = next; 4360 } while (r != NULL); 4361 4362 return false; 4363 } 4364 4365 uint humongous_objects_reclaimed() { 4366 return _humongous_objects_reclaimed; 4367 } 4368 4369 uint humongous_regions_reclaimed() { 4370 return _humongous_regions_reclaimed; 4371 } 4372 4373 size_t bytes_freed() const { 4374 return _freed_bytes; 4375 } 4376 }; 4377 4378 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4379 assert_at_safepoint_on_vm_thread(); 4380 4381 if (!G1EagerReclaimHumongousObjects || 4382 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4383 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4384 return; 4385 } 4386 4387 double start_time = os::elapsedTime(); 4388 4389 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4390 4391 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4392 heap_region_iterate(&cl); 4393 4394 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4395 4396 G1HRPrinter* hrp = hr_printer(); 4397 if (hrp->is_active()) { 4398 FreeRegionListIterator iter(&local_cleanup_list); 4399 while (iter.more_available()) { 4400 HeapRegion* hr = iter.get_next(); 4401 hrp->cleanup(hr); 4402 } 4403 } 4404 4405 prepend_to_freelist(&local_cleanup_list); 4406 decrement_summary_bytes(cl.bytes_freed()); 4407 4408 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4409 cl.humongous_objects_reclaimed()); 4410 } 4411 4412 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4413 public: 4414 virtual bool do_heap_region(HeapRegion* r) { 4415 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4416 G1CollectedHeap::heap()->clear_in_cset(r); 4417 r->set_young_index_in_cset(-1); 4418 return false; 4419 } 4420 }; 4421 4422 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4423 G1AbandonCollectionSetClosure cl; 4424 collection_set->iterate(&cl); 4425 4426 collection_set->clear(); 4427 collection_set->stop_incremental_building(); 4428 } 4429 4430 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4431 return _allocator->is_retained_old_region(hr); 4432 } 4433 4434 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4435 _eden.add(hr); 4436 _g1_policy->set_region_eden(hr); 4437 } 4438 4439 #ifdef ASSERT 4440 4441 class NoYoungRegionsClosure: public HeapRegionClosure { 4442 private: 4443 bool _success; 4444 public: 4445 NoYoungRegionsClosure() : _success(true) { } 4446 bool do_heap_region(HeapRegion* r) { 4447 if (r->is_young()) { 4448 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4449 p2i(r->bottom()), p2i(r->end())); 4450 _success = false; 4451 } 4452 return false; 4453 } 4454 bool success() { return _success; } 4455 }; 4456 4457 bool G1CollectedHeap::check_young_list_empty() { 4458 bool ret = (young_regions_count() == 0); 4459 4460 NoYoungRegionsClosure closure; 4461 heap_region_iterate(&closure); 4462 ret = ret && closure.success(); 4463 4464 return ret; 4465 } 4466 4467 #endif // ASSERT 4468 4469 class TearDownRegionSetsClosure : public HeapRegionClosure { 4470 HeapRegionSet *_old_set; 4471 4472 public: 4473 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4474 4475 bool do_heap_region(HeapRegion* r) { 4476 if (r->is_old()) { 4477 _old_set->remove(r); 4478 } else if(r->is_young()) { 4479 r->uninstall_surv_rate_group(); 4480 } else { 4481 // We ignore free regions, we'll empty the free list afterwards. 4482 // We ignore humongous and archive regions, we're not tearing down these 4483 // sets. 4484 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4485 "it cannot be another type"); 4486 } 4487 return false; 4488 } 4489 4490 ~TearDownRegionSetsClosure() { 4491 assert(_old_set->is_empty(), "post-condition"); 4492 } 4493 }; 4494 4495 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4496 assert_at_safepoint_on_vm_thread(); 4497 4498 if (!free_list_only) { 4499 TearDownRegionSetsClosure cl(&_old_set); 4500 heap_region_iterate(&cl); 4501 4502 // Note that emptying the _young_list is postponed and instead done as 4503 // the first step when rebuilding the regions sets again. The reason for 4504 // this is that during a full GC string deduplication needs to know if 4505 // a collected region was young or old when the full GC was initiated. 4506 } 4507 _hrm.remove_all_free_regions(); 4508 } 4509 4510 void G1CollectedHeap::increase_used(size_t bytes) { 4511 _summary_bytes_used += bytes; 4512 } 4513 4514 void G1CollectedHeap::decrease_used(size_t bytes) { 4515 assert(_summary_bytes_used >= bytes, 4516 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4517 _summary_bytes_used, bytes); 4518 _summary_bytes_used -= bytes; 4519 } 4520 4521 void G1CollectedHeap::set_used(size_t bytes) { 4522 _summary_bytes_used = bytes; 4523 } 4524 4525 class RebuildRegionSetsClosure : public HeapRegionClosure { 4526 private: 4527 bool _free_list_only; 4528 4529 HeapRegionSet* _old_set; 4530 HeapRegionManager* _hrm; 4531 4532 size_t _total_used; 4533 4534 public: 4535 RebuildRegionSetsClosure(bool free_list_only, 4536 HeapRegionSet* old_set, 4537 HeapRegionManager* hrm) : 4538 _free_list_only(free_list_only), 4539 _old_set(old_set), _hrm(hrm), _total_used(0) { 4540 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4541 if (!free_list_only) { 4542 assert(_old_set->is_empty(), "pre-condition"); 4543 } 4544 } 4545 4546 bool do_heap_region(HeapRegion* r) { 4547 if (r->is_empty()) { 4548 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4549 // Add free regions to the free list 4550 r->set_free(); 4551 _hrm->insert_into_free_list(r); 4552 } else if (!_free_list_only) { 4553 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4554 4555 if (r->is_archive() || r->is_humongous()) { 4556 // We ignore archive and humongous regions. We left these sets unchanged. 4557 } else { 4558 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4559 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4560 r->move_to_old(); 4561 _old_set->add(r); 4562 } 4563 _total_used += r->used(); 4564 } 4565 4566 return false; 4567 } 4568 4569 size_t total_used() { 4570 return _total_used; 4571 } 4572 }; 4573 4574 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4575 assert_at_safepoint_on_vm_thread(); 4576 4577 if (!free_list_only) { 4578 _eden.clear(); 4579 _survivor.clear(); 4580 } 4581 4582 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 4583 heap_region_iterate(&cl); 4584 4585 if (!free_list_only) { 4586 set_used(cl.total_used()); 4587 if (_archive_allocator != NULL) { 4588 _archive_allocator->clear_used(); 4589 } 4590 } 4591 assert(used() == recalculate_used(), 4592 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4593 used(), recalculate_used()); 4594 } 4595 4596 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4597 HeapRegion* hr = heap_region_containing(p); 4598 return hr->is_in(p); 4599 } 4600 4601 // Methods for the mutator alloc region 4602 4603 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4604 bool force) { 4605 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4606 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4607 if (force || should_allocate) { 4608 HeapRegion* new_alloc_region = new_region(word_size, 4609 false /* is_old */, 4610 false /* do_expand */); 4611 if (new_alloc_region != NULL) { 4612 set_region_short_lived_locked(new_alloc_region); 4613 _hr_printer.alloc(new_alloc_region, !should_allocate); 4614 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4615 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4616 return new_alloc_region; 4617 } 4618 } 4619 return NULL; 4620 } 4621 4622 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4623 size_t allocated_bytes) { 4624 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4625 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4626 4627 collection_set()->add_eden_region(alloc_region); 4628 increase_used(allocated_bytes); 4629 _hr_printer.retire(alloc_region); 4630 // We update the eden sizes here, when the region is retired, 4631 // instead of when it's allocated, since this is the point that its 4632 // used space has been recorded in _summary_bytes_used. 4633 g1mm()->update_eden_size(); 4634 } 4635 4636 // Methods for the GC alloc regions 4637 4638 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4639 if (dest.is_old()) { 4640 return true; 4641 } else { 4642 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4643 } 4644 } 4645 4646 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4647 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4648 4649 if (!has_more_regions(dest)) { 4650 return NULL; 4651 } 4652 4653 const bool is_survivor = dest.is_young(); 4654 4655 HeapRegion* new_alloc_region = new_region(word_size, 4656 !is_survivor, 4657 true /* do_expand */); 4658 if (new_alloc_region != NULL) { 4659 if (is_survivor) { 4660 new_alloc_region->set_survivor(); 4661 _survivor.add(new_alloc_region); 4662 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4663 } else { 4664 new_alloc_region->set_old(); 4665 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4666 } 4667 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4668 _hr_printer.alloc(new_alloc_region); 4669 bool during_im = collector_state()->in_initial_mark_gc(); 4670 new_alloc_region->note_start_of_copying(during_im); 4671 return new_alloc_region; 4672 } 4673 return NULL; 4674 } 4675 4676 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4677 size_t allocated_bytes, 4678 InCSetState dest) { 4679 bool during_im = collector_state()->in_initial_mark_gc(); 4680 alloc_region->note_end_of_copying(during_im); 4681 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4682 if (dest.is_old()) { 4683 old_set_add(alloc_region); 4684 } 4685 _hr_printer.retire(alloc_region); 4686 } 4687 4688 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4689 bool expanded = false; 4690 uint index = _hrm.find_highest_free(&expanded); 4691 4692 if (index != G1_NO_HRM_INDEX) { 4693 if (expanded) { 4694 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4695 HeapRegion::GrainWords * HeapWordSize); 4696 } 4697 _hrm.allocate_free_regions_starting_at(index, 1); 4698 return region_at(index); 4699 } 4700 return NULL; 4701 } 4702 4703 // Optimized nmethod scanning 4704 4705 class RegisterNMethodOopClosure: public OopClosure { 4706 G1CollectedHeap* _g1h; 4707 nmethod* _nm; 4708 4709 template <class T> void do_oop_work(T* p) { 4710 T heap_oop = RawAccess<>::oop_load(p); 4711 if (!CompressedOops::is_null(heap_oop)) { 4712 oop obj = CompressedOops::decode_not_null(heap_oop); 4713 HeapRegion* hr = _g1h->heap_region_containing(obj); 4714 assert(!hr->is_continues_humongous(), 4715 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4716 " starting at " HR_FORMAT, 4717 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4718 4719 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4720 hr->add_strong_code_root_locked(_nm); 4721 } 4722 } 4723 4724 public: 4725 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4726 _g1h(g1h), _nm(nm) {} 4727 4728 void do_oop(oop* p) { do_oop_work(p); } 4729 void do_oop(narrowOop* p) { do_oop_work(p); } 4730 }; 4731 4732 class UnregisterNMethodOopClosure: public OopClosure { 4733 G1CollectedHeap* _g1h; 4734 nmethod* _nm; 4735 4736 template <class T> void do_oop_work(T* p) { 4737 T heap_oop = RawAccess<>::oop_load(p); 4738 if (!CompressedOops::is_null(heap_oop)) { 4739 oop obj = CompressedOops::decode_not_null(heap_oop); 4740 HeapRegion* hr = _g1h->heap_region_containing(obj); 4741 assert(!hr->is_continues_humongous(), 4742 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4743 " starting at " HR_FORMAT, 4744 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4745 4746 hr->remove_strong_code_root(_nm); 4747 } 4748 } 4749 4750 public: 4751 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4752 _g1h(g1h), _nm(nm) {} 4753 4754 void do_oop(oop* p) { do_oop_work(p); } 4755 void do_oop(narrowOop* p) { do_oop_work(p); } 4756 }; 4757 4758 // Returns true if the reference points to an object that 4759 // can move in an incremental collection. 4760 bool G1CollectedHeap::is_scavengable(oop obj) { 4761 HeapRegion* hr = heap_region_containing(obj); 4762 return !hr->is_pinned(); 4763 } 4764 4765 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4766 guarantee(nm != NULL, "sanity"); 4767 RegisterNMethodOopClosure reg_cl(this, nm); 4768 nm->oops_do(®_cl); 4769 } 4770 4771 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4772 guarantee(nm != NULL, "sanity"); 4773 UnregisterNMethodOopClosure reg_cl(this, nm); 4774 nm->oops_do(®_cl, true); 4775 } 4776 4777 void G1CollectedHeap::purge_code_root_memory() { 4778 double purge_start = os::elapsedTime(); 4779 G1CodeRootSet::purge(); 4780 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4781 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4782 } 4783 4784 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4785 G1CollectedHeap* _g1h; 4786 4787 public: 4788 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4789 _g1h(g1h) {} 4790 4791 void do_code_blob(CodeBlob* cb) { 4792 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4793 if (nm == NULL) { 4794 return; 4795 } 4796 4797 if (ScavengeRootsInCode) { 4798 _g1h->register_nmethod(nm); 4799 } 4800 } 4801 }; 4802 4803 void G1CollectedHeap::rebuild_strong_code_roots() { 4804 RebuildStrongCodeRootClosure blob_cl(this); 4805 CodeCache::blobs_do(&blob_cl); 4806 } 4807 4808 void G1CollectedHeap::initialize_serviceability() { 4809 _g1mm->initialize_serviceability(); 4810 } 4811 4812 MemoryUsage G1CollectedHeap::memory_usage() { 4813 return _g1mm->memory_usage(); 4814 } 4815 4816 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4817 return _g1mm->memory_managers(); 4818 } 4819 4820 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4821 return _g1mm->memory_pools(); 4822 }