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) { 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::set_range_archive(ranges[i], false); 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 hrm()->prepare_for_full_collection_start(); 1030 } 1031 1032 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1033 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1034 assert(used() == recalculate_used(), "Should be equal"); 1035 _verifier->verify_region_sets_optional(); 1036 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1037 _verifier->check_bitmaps("Full GC Start"); 1038 } 1039 1040 void G1CollectedHeap::prepare_heap_for_mutators() { 1041 hrm()->prepare_for_full_collection_end(); 1042 1043 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1044 ClassLoaderDataGraph::purge(); 1045 MetaspaceUtils::verify_metrics(); 1046 1047 // Prepare heap for normal collections. 1048 assert(num_free_regions() == 0, "we should not have added any free regions"); 1049 rebuild_region_sets(false /* free_list_only */); 1050 abort_refinement(); 1051 resize_heap_if_necessary(); 1052 1053 // Rebuild the strong code root lists for each region 1054 rebuild_strong_code_roots(); 1055 1056 // Purge code root memory 1057 purge_code_root_memory(); 1058 1059 // Start a new incremental collection set for the next pause 1060 start_new_collection_set(); 1061 1062 _allocator->init_mutator_alloc_region(); 1063 1064 // Post collection state updates. 1065 MetaspaceGC::compute_new_size(); 1066 } 1067 1068 void G1CollectedHeap::abort_refinement() { 1069 if (_hot_card_cache->use_cache()) { 1070 _hot_card_cache->reset_hot_cache(); 1071 } 1072 1073 // Discard all remembered set updates. 1074 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1075 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1076 } 1077 1078 void G1CollectedHeap::verify_after_full_collection() { 1079 _hrm->verify_optional(); 1080 _verifier->verify_region_sets_optional(); 1081 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1082 // Clear the previous marking bitmap, if needed for bitmap verification. 1083 // Note we cannot do this when we clear the next marking bitmap in 1084 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1085 // objects marked during a full GC against the previous bitmap. 1086 // But we need to clear it before calling check_bitmaps below since 1087 // the full GC has compacted objects and updated TAMS but not updated 1088 // the prev bitmap. 1089 if (G1VerifyBitmaps) { 1090 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification"); 1091 _cm->clear_prev_bitmap(workers()); 1092 } 1093 // This call implicitly verifies that the next bitmap is clear after Full GC. 1094 _verifier->check_bitmaps("Full GC End"); 1095 1096 // At this point there should be no regions in the 1097 // entire heap tagged as young. 1098 assert(check_young_list_empty(), "young list should be empty at this point"); 1099 1100 // Note: since we've just done a full GC, concurrent 1101 // marking is no longer active. Therefore we need not 1102 // re-enable reference discovery for the CM ref processor. 1103 // That will be done at the start of the next marking cycle. 1104 // We also know that the STW processor should no longer 1105 // discover any new references. 1106 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1107 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1108 _ref_processor_stw->verify_no_references_recorded(); 1109 _ref_processor_cm->verify_no_references_recorded(); 1110 } 1111 1112 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1113 // Post collection logging. 1114 // We should do this after we potentially resize the heap so 1115 // that all the COMMIT / UNCOMMIT events are generated before 1116 // the compaction events. 1117 print_hrm_post_compaction(); 1118 heap_transition->print(); 1119 print_heap_after_gc(); 1120 print_heap_regions(); 1121 #ifdef TRACESPINNING 1122 ParallelTaskTerminator::print_termination_counts(); 1123 #endif 1124 } 1125 1126 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1127 bool clear_all_soft_refs) { 1128 assert_at_safepoint_on_vm_thread(); 1129 1130 if (GCLocker::check_active_before_gc()) { 1131 // Full GC was not completed. 1132 return false; 1133 } 1134 1135 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1136 soft_ref_policy()->should_clear_all_soft_refs(); 1137 1138 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1139 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1140 1141 collector.prepare_collection(); 1142 collector.collect(); 1143 collector.complete_collection(); 1144 1145 // Full collection was successfully completed. 1146 return true; 1147 } 1148 1149 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1150 // Currently, there is no facility in the do_full_collection(bool) API to notify 1151 // the caller that the collection did not succeed (e.g., because it was locked 1152 // out by the GC locker). So, right now, we'll ignore the return value. 1153 bool dummy = do_full_collection(true, /* explicit_gc */ 1154 clear_all_soft_refs); 1155 } 1156 1157 void G1CollectedHeap::resize_heap_if_necessary() { 1158 // Capacity, free and used after the GC counted as full regions to 1159 // include the waste in the following calculations. 1160 const size_t capacity_after_gc = capacity(); 1161 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1162 1163 // This is enforced in arguments.cpp. 1164 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1165 "otherwise the code below doesn't make sense"); 1166 1167 // We don't have floating point command-line arguments 1168 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1169 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1170 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1171 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1172 1173 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1174 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1175 1176 // We have to be careful here as these two calculations can overflow 1177 // 32-bit size_t's. 1178 double used_after_gc_d = (double) used_after_gc; 1179 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1180 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1181 1182 // Let's make sure that they are both under the max heap size, which 1183 // by default will make them fit into a size_t. 1184 double desired_capacity_upper_bound = (double) max_heap_size; 1185 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1186 desired_capacity_upper_bound); 1187 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1188 desired_capacity_upper_bound); 1189 1190 // We can now safely turn them into size_t's. 1191 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1192 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1193 1194 // This assert only makes sense here, before we adjust them 1195 // with respect to the min and max heap size. 1196 assert(minimum_desired_capacity <= maximum_desired_capacity, 1197 "minimum_desired_capacity = " SIZE_FORMAT ", " 1198 "maximum_desired_capacity = " SIZE_FORMAT, 1199 minimum_desired_capacity, maximum_desired_capacity); 1200 1201 // Should not be greater than the heap max size. No need to adjust 1202 // it with respect to the heap min size as it's a lower bound (i.e., 1203 // we'll try to make the capacity larger than it, not smaller). 1204 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1205 // Should not be less than the heap min size. No need to adjust it 1206 // with respect to the heap max size as it's an upper bound (i.e., 1207 // we'll try to make the capacity smaller than it, not greater). 1208 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1209 1210 if (capacity_after_gc < minimum_desired_capacity) { 1211 // Don't expand unless it's significant 1212 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1213 1214 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). " 1215 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1216 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1217 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1218 1219 expand(expand_bytes, _workers); 1220 1221 // No expansion, now see if we want to shrink 1222 } else if (capacity_after_gc > maximum_desired_capacity) { 1223 // Capacity too large, compute shrinking size 1224 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1225 1226 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). " 1227 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1228 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1229 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1230 1231 shrink(shrink_bytes); 1232 } 1233 } 1234 1235 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1236 bool do_gc, 1237 bool clear_all_soft_refs, 1238 bool expect_null_mutator_alloc_region, 1239 bool* gc_succeeded) { 1240 *gc_succeeded = true; 1241 // Let's attempt the allocation first. 1242 HeapWord* result = 1243 attempt_allocation_at_safepoint(word_size, 1244 expect_null_mutator_alloc_region); 1245 if (result != NULL) { 1246 return result; 1247 } 1248 1249 // In a G1 heap, we're supposed to keep allocation from failing by 1250 // incremental pauses. Therefore, at least for now, we'll favor 1251 // expansion over collection. (This might change in the future if we can 1252 // do something smarter than full collection to satisfy a failed alloc.) 1253 result = expand_and_allocate(word_size); 1254 if (result != NULL) { 1255 return result; 1256 } 1257 1258 if (do_gc) { 1259 // Expansion didn't work, we'll try to do a Full GC. 1260 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1261 clear_all_soft_refs); 1262 } 1263 1264 return NULL; 1265 } 1266 1267 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1268 bool* succeeded) { 1269 assert_at_safepoint_on_vm_thread(); 1270 1271 // Attempts to allocate followed by Full GC. 1272 HeapWord* result = 1273 satisfy_failed_allocation_helper(word_size, 1274 true, /* do_gc */ 1275 false, /* clear_all_soft_refs */ 1276 false, /* expect_null_mutator_alloc_region */ 1277 succeeded); 1278 1279 if (result != NULL || !*succeeded) { 1280 return result; 1281 } 1282 1283 // Attempts to allocate followed by Full GC that will collect all soft references. 1284 result = satisfy_failed_allocation_helper(word_size, 1285 true, /* do_gc */ 1286 true, /* clear_all_soft_refs */ 1287 true, /* expect_null_mutator_alloc_region */ 1288 succeeded); 1289 1290 if (result != NULL || !*succeeded) { 1291 return result; 1292 } 1293 1294 // Attempts to allocate, no GC 1295 result = satisfy_failed_allocation_helper(word_size, 1296 false, /* do_gc */ 1297 false, /* clear_all_soft_refs */ 1298 true, /* expect_null_mutator_alloc_region */ 1299 succeeded); 1300 1301 if (result != NULL) { 1302 return result; 1303 } 1304 1305 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1306 "Flag should have been handled and cleared prior to this point"); 1307 1308 // What else? We might try synchronous finalization later. If the total 1309 // space available is large enough for the allocation, then a more 1310 // complete compaction phase than we've tried so far might be 1311 // appropriate. 1312 return NULL; 1313 } 1314 1315 // Attempting to expand the heap sufficiently 1316 // to support an allocation of the given "word_size". If 1317 // successful, perform the allocation and return the address of the 1318 // allocated block, or else "NULL". 1319 1320 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1321 assert_at_safepoint_on_vm_thread(); 1322 1323 _verifier->verify_region_sets_optional(); 1324 1325 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1326 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1327 word_size * HeapWordSize); 1328 1329 1330 if (expand(expand_bytes, _workers)) { 1331 _hrm->verify_optional(); 1332 _verifier->verify_region_sets_optional(); 1333 return attempt_allocation_at_safepoint(word_size, 1334 false /* expect_null_mutator_alloc_region */); 1335 } 1336 return NULL; 1337 } 1338 1339 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1340 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1341 aligned_expand_bytes = align_up(aligned_expand_bytes, 1342 HeapRegion::GrainBytes); 1343 1344 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1345 expand_bytes, aligned_expand_bytes); 1346 1347 if (is_maximal_no_gc()) { 1348 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1349 return false; 1350 } 1351 1352 double expand_heap_start_time_sec = os::elapsedTime(); 1353 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1354 assert(regions_to_expand > 0, "Must expand by at least one region"); 1355 1356 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers); 1357 if (expand_time_ms != NULL) { 1358 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1359 } 1360 1361 if (expanded_by > 0) { 1362 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1363 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1364 g1_policy()->record_new_heap_size(num_regions()); 1365 } else { 1366 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1367 1368 // The expansion of the virtual storage space was unsuccessful. 1369 // Let's see if it was because we ran out of swap. 1370 if (G1ExitOnExpansionFailure && 1371 _hrm->available() >= regions_to_expand) { 1372 // We had head room... 1373 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1374 } 1375 } 1376 return regions_to_expand > 0; 1377 } 1378 1379 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1380 size_t aligned_shrink_bytes = 1381 ReservedSpace::page_align_size_down(shrink_bytes); 1382 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1383 HeapRegion::GrainBytes); 1384 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1385 1386 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove); 1387 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1388 1389 1390 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", 1391 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1392 if (num_regions_removed > 0) { 1393 g1_policy()->record_new_heap_size(num_regions()); 1394 } else { 1395 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1396 } 1397 } 1398 1399 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1400 _verifier->verify_region_sets_optional(); 1401 1402 // We should only reach here at the end of a Full GC or during Remark which 1403 // means we should not not be holding to any GC alloc regions. The method 1404 // below will make sure of that and do any remaining clean up. 1405 _allocator->abandon_gc_alloc_regions(); 1406 1407 // Instead of tearing down / rebuilding the free lists here, we 1408 // could instead use the remove_all_pending() method on free_list to 1409 // remove only the ones that we need to remove. 1410 tear_down_region_sets(true /* free_list_only */); 1411 shrink_helper(shrink_bytes); 1412 rebuild_region_sets(true /* free_list_only */); 1413 1414 _hrm->verify_optional(); 1415 _verifier->verify_region_sets_optional(); 1416 } 1417 1418 class OldRegionSetChecker : public HeapRegionSetChecker { 1419 public: 1420 void check_mt_safety() { 1421 // Master Old Set MT safety protocol: 1422 // (a) If we're at a safepoint, operations on the master old set 1423 // should be invoked: 1424 // - by the VM thread (which will serialize them), or 1425 // - by the GC workers while holding the FreeList_lock, if we're 1426 // at a safepoint for an evacuation pause (this lock is taken 1427 // anyway when an GC alloc region is retired so that a new one 1428 // is allocated from the free list), or 1429 // - by the GC workers while holding the OldSets_lock, if we're at a 1430 // safepoint for a cleanup pause. 1431 // (b) If we're not at a safepoint, operations on the master old set 1432 // should be invoked while holding the Heap_lock. 1433 1434 if (SafepointSynchronize::is_at_safepoint()) { 1435 guarantee(Thread::current()->is_VM_thread() || 1436 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1437 "master old set MT safety protocol at a safepoint"); 1438 } else { 1439 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1440 } 1441 } 1442 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1443 const char* get_description() { return "Old Regions"; } 1444 }; 1445 1446 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1447 public: 1448 void check_mt_safety() { 1449 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1450 "May only change archive regions during initialization or safepoint."); 1451 } 1452 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1453 const char* get_description() { return "Archive Regions"; } 1454 }; 1455 1456 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1457 public: 1458 void check_mt_safety() { 1459 // Humongous Set MT safety protocol: 1460 // (a) If we're at a safepoint, operations on the master humongous 1461 // set should be invoked by either the VM thread (which will 1462 // serialize them) or by the GC workers while holding the 1463 // OldSets_lock. 1464 // (b) If we're not at a safepoint, operations on the master 1465 // humongous set should be invoked while holding the Heap_lock. 1466 1467 if (SafepointSynchronize::is_at_safepoint()) { 1468 guarantee(Thread::current()->is_VM_thread() || 1469 OldSets_lock->owned_by_self(), 1470 "master humongous set MT safety protocol at a safepoint"); 1471 } else { 1472 guarantee(Heap_lock->owned_by_self(), 1473 "master humongous set MT safety protocol outside a safepoint"); 1474 } 1475 } 1476 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1477 const char* get_description() { return "Humongous Regions"; } 1478 }; 1479 1480 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1481 CollectedHeap(), 1482 _young_gen_sampling_thread(NULL), 1483 _workers(NULL), 1484 _collector_policy(collector_policy), 1485 _card_table(NULL), 1486 _soft_ref_policy(), 1487 _old_set("Old Region Set", new OldRegionSetChecker()), 1488 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1489 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1490 _bot(NULL), 1491 _listener(), 1492 _hrm(NULL), 1493 _is_hetero_heap(AllocateOldGenAt != NULL), 1494 _allocator(NULL), 1495 _verifier(NULL), 1496 _summary_bytes_used(0), 1497 _archive_allocator(NULL), 1498 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1499 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1500 _expand_heap_after_alloc_failure(true), 1501 _g1mm(NULL), 1502 _humongous_reclaim_candidates(), 1503 _has_humongous_reclaim_candidates(false), 1504 _hr_printer(), 1505 _collector_state(), 1506 _old_marking_cycles_started(0), 1507 _old_marking_cycles_completed(0), 1508 _eden(), 1509 _survivor(), 1510 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1511 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1512 _g1_policy(new G1Policy(_gc_timer_stw)), 1513 _heap_sizing_policy(NULL), 1514 _collection_set(this, _g1_policy), 1515 _hot_card_cache(NULL), 1516 _g1_rem_set(NULL), 1517 _dirty_card_queue_set(false), 1518 _cm(NULL), 1519 _cm_thread(NULL), 1520 _cr(NULL), 1521 _task_queues(NULL), 1522 _evacuation_failed(false), 1523 _evacuation_failed_info_array(NULL), 1524 _preserved_marks_set(true /* in_c_heap */), 1525 #ifndef PRODUCT 1526 _evacuation_failure_alot_for_current_gc(false), 1527 _evacuation_failure_alot_gc_number(0), 1528 _evacuation_failure_alot_count(0), 1529 #endif 1530 _ref_processor_stw(NULL), 1531 _is_alive_closure_stw(this), 1532 _is_subject_to_discovery_stw(this), 1533 _ref_processor_cm(NULL), 1534 _is_alive_closure_cm(this), 1535 _is_subject_to_discovery_cm(this), 1536 _in_cset_fast_test() { 1537 1538 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1539 true /* are_GC_task_threads */, 1540 false /* are_ConcurrentGC_threads */); 1541 _workers->initialize_workers(); 1542 _verifier = new G1HeapVerifier(this); 1543 1544 _allocator = new G1Allocator(this); 1545 1546 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1547 1548 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1549 1550 // Override the default _filler_array_max_size so that no humongous filler 1551 // objects are created. 1552 _filler_array_max_size = _humongous_object_threshold_in_words; 1553 1554 uint n_queues = ParallelGCThreads; 1555 _task_queues = new RefToScanQueueSet(n_queues); 1556 1557 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1558 1559 for (uint i = 0; i < n_queues; i++) { 1560 RefToScanQueue* q = new RefToScanQueue(); 1561 q->initialize(); 1562 _task_queues->register_queue(i, q); 1563 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1564 } 1565 1566 // Initialize the G1EvacuationFailureALot counters and flags. 1567 NOT_PRODUCT(reset_evacuation_should_fail();) 1568 1569 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1570 } 1571 1572 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1573 size_t size, 1574 size_t translation_factor) { 1575 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1576 // Allocate a new reserved space, preferring to use large pages. 1577 ReservedSpace rs(size, preferred_page_size); 1578 G1RegionToSpaceMapper* result = 1579 G1RegionToSpaceMapper::create_mapper(rs, 1580 size, 1581 rs.alignment(), 1582 HeapRegion::GrainBytes, 1583 translation_factor, 1584 mtGC); 1585 1586 os::trace_page_sizes_for_requested_size(description, 1587 size, 1588 preferred_page_size, 1589 rs.alignment(), 1590 rs.base(), 1591 rs.size()); 1592 1593 return result; 1594 } 1595 1596 jint G1CollectedHeap::initialize_concurrent_refinement() { 1597 jint ecode = JNI_OK; 1598 _cr = G1ConcurrentRefine::create(&ecode); 1599 return ecode; 1600 } 1601 1602 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1603 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1604 if (_young_gen_sampling_thread->osthread() == NULL) { 1605 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1606 return JNI_ENOMEM; 1607 } 1608 return JNI_OK; 1609 } 1610 1611 jint G1CollectedHeap::initialize() { 1612 os::enable_vtime(); 1613 1614 // Necessary to satisfy locking discipline assertions. 1615 1616 MutexLocker x(Heap_lock); 1617 1618 // While there are no constraints in the GC code that HeapWordSize 1619 // be any particular value, there are multiple other areas in the 1620 // system which believe this to be true (e.g. oop->object_size in some 1621 // cases incorrectly returns the size in wordSize units rather than 1622 // HeapWordSize). 1623 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1624 1625 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1626 size_t max_byte_size = g1_collector_policy()->heap_reservation_size_bytes(); 1627 size_t heap_alignment = collector_policy()->heap_alignment(); 1628 1629 // Ensure that the sizes are properly aligned. 1630 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1631 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1632 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1633 1634 // Reserve the maximum. 1635 1636 // When compressed oops are enabled, the preferred heap base 1637 // is calculated by subtracting the requested size from the 1638 // 32Gb boundary and using the result as the base address for 1639 // heap reservation. If the requested size is not aligned to 1640 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1641 // into the ReservedHeapSpace constructor) then the actual 1642 // base of the reserved heap may end up differing from the 1643 // address that was requested (i.e. the preferred heap base). 1644 // If this happens then we could end up using a non-optimal 1645 // compressed oops mode. 1646 1647 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1648 heap_alignment); 1649 1650 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1651 1652 // Create the barrier set for the entire reserved region. 1653 G1CardTable* ct = new G1CardTable(reserved_region()); 1654 ct->initialize(); 1655 G1BarrierSet* bs = new G1BarrierSet(ct); 1656 bs->initialize(); 1657 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1658 BarrierSet::set_barrier_set(bs); 1659 _card_table = ct; 1660 1661 G1BarrierSet::satb_mark_queue_set().initialize(this, 1662 SATB_Q_CBL_mon, 1663 &bs->satb_mark_queue_buffer_allocator(), 1664 G1SATBProcessCompletedThreshold, 1665 G1SATBBufferEnqueueingThresholdPercent, 1666 Shared_SATB_Q_lock); 1667 1668 // process_completed_threshold and max_completed_queue are updated 1669 // later, based on the concurrent refinement object. 1670 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1671 &bs->dirty_card_queue_buffer_allocator(), 1672 -1, // temp. never trigger 1673 -1, // temp. no limit 1674 Shared_DirtyCardQ_lock, 1675 true); // init_free_ids 1676 1677 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1678 &bs->dirty_card_queue_buffer_allocator(), 1679 -1, // never trigger processing 1680 -1, // no limit on length 1681 Shared_DirtyCardQ_lock); 1682 1683 // Create the hot card cache. 1684 _hot_card_cache = new G1HotCardCache(this); 1685 1686 // Carve out the G1 part of the heap. 1687 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1688 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1689 G1RegionToSpaceMapper* heap_storage = 1690 G1RegionToSpaceMapper::create_heap_mapper(g1_rs, 1691 g1_rs.size(), 1692 page_size, 1693 HeapRegion::GrainBytes, 1694 1, 1695 mtJavaHeap); 1696 if(heap_storage == NULL) { 1697 vm_shutdown_during_initialization("Could not initialize G1 heap"); 1698 return JNI_ERR; 1699 } 1700 1701 os::trace_page_sizes("Heap", 1702 collector_policy()->min_heap_byte_size(), 1703 max_byte_size, 1704 page_size, 1705 heap_rs.base(), 1706 heap_rs.size()); 1707 heap_storage->set_mapping_changed_listener(&_listener); 1708 1709 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1710 G1RegionToSpaceMapper* bot_storage = 1711 create_aux_memory_mapper("Block Offset Table", 1712 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1713 G1BlockOffsetTable::heap_map_factor()); 1714 1715 G1RegionToSpaceMapper* cardtable_storage = 1716 create_aux_memory_mapper("Card Table", 1717 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1718 G1CardTable::heap_map_factor()); 1719 1720 G1RegionToSpaceMapper* card_counts_storage = 1721 create_aux_memory_mapper("Card Counts Table", 1722 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1723 G1CardCounts::heap_map_factor()); 1724 1725 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1726 G1RegionToSpaceMapper* prev_bitmap_storage = 1727 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1728 G1RegionToSpaceMapper* next_bitmap_storage = 1729 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1730 1731 _hrm = HeapRegionManager::create_manager(this, collector_policy()); 1732 1733 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1734 _card_table->initialize(cardtable_storage); 1735 // Do later initialization work for concurrent refinement. 1736 _hot_card_cache->initialize(card_counts_storage); 1737 1738 // 6843694 - ensure that the maximum region index can fit 1739 // in the remembered set structures. 1740 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1741 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1742 1743 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1744 // start within the first card. 1745 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1746 // Also create a G1 rem set. 1747 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1748 _g1_rem_set->initialize(max_reserved_capacity(), max_regions()); 1749 1750 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1751 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1752 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1753 "too many cards per region"); 1754 1755 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1); 1756 1757 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1758 1759 { 1760 HeapWord* start = _hrm->reserved().start(); 1761 HeapWord* end = _hrm->reserved().end(); 1762 size_t granularity = HeapRegion::GrainBytes; 1763 1764 _in_cset_fast_test.initialize(start, end, granularity); 1765 _humongous_reclaim_candidates.initialize(start, end, granularity); 1766 } 1767 1768 // Create the G1ConcurrentMark data structure and thread. 1769 // (Must do this late, so that "max_regions" is defined.) 1770 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1771 if (_cm == NULL || !_cm->completed_initialization()) { 1772 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1773 return JNI_ENOMEM; 1774 } 1775 _cm_thread = _cm->cm_thread(); 1776 1777 // Now expand into the initial heap size. 1778 if (!expand(init_byte_size, _workers)) { 1779 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1780 return JNI_ENOMEM; 1781 } 1782 1783 // Perform any initialization actions delegated to the policy. 1784 g1_policy()->init(this, &_collection_set); 1785 1786 // Now we know the target length of young list. So adjust the heap to provision that many regions on dram. 1787 if (is_hetero_heap()) { 1788 static_cast<HeterogeneousHeapRegionManager*>(hrm())->adjust_dram_regions((uint)g1_policy()->young_list_target_length(), workers()); 1789 } 1790 1791 jint ecode = initialize_concurrent_refinement(); 1792 if (ecode != JNI_OK) { 1793 return ecode; 1794 } 1795 1796 ecode = initialize_young_gen_sampling_thread(); 1797 if (ecode != JNI_OK) { 1798 return ecode; 1799 } 1800 1801 { 1802 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1803 dcqs.set_process_completed_threshold((int)concurrent_refine()->yellow_zone()); 1804 dcqs.set_max_completed_queue((int)concurrent_refine()->red_zone()); 1805 } 1806 1807 // Here we allocate the dummy HeapRegion that is required by the 1808 // G1AllocRegion class. 1809 HeapRegion* dummy_region = _hrm->get_dummy_region(); 1810 1811 // We'll re-use the same region whether the alloc region will 1812 // require BOT updates or not and, if it doesn't, then a non-young 1813 // region will complain that it cannot support allocations without 1814 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1815 dummy_region->set_eden(); 1816 // Make sure it's full. 1817 dummy_region->set_top(dummy_region->end()); 1818 G1AllocRegion::setup(this, dummy_region); 1819 1820 _allocator->init_mutator_alloc_region(); 1821 1822 // Do create of the monitoring and management support so that 1823 // values in the heap have been properly initialized. 1824 _g1mm = new G1MonitoringSupport(this); 1825 1826 G1StringDedup::initialize(); 1827 1828 _preserved_marks_set.init(ParallelGCThreads); 1829 1830 _collection_set.initialize(max_regions()); 1831 1832 return JNI_OK; 1833 } 1834 1835 void G1CollectedHeap::stop() { 1836 // Stop all concurrent threads. We do this to make sure these threads 1837 // do not continue to execute and access resources (e.g. logging) 1838 // that are destroyed during shutdown. 1839 _cr->stop(); 1840 _young_gen_sampling_thread->stop(); 1841 _cm_thread->stop(); 1842 if (G1StringDedup::is_enabled()) { 1843 G1StringDedup::stop(); 1844 } 1845 } 1846 1847 void G1CollectedHeap::safepoint_synchronize_begin() { 1848 SuspendibleThreadSet::synchronize(); 1849 } 1850 1851 void G1CollectedHeap::safepoint_synchronize_end() { 1852 SuspendibleThreadSet::desynchronize(); 1853 } 1854 1855 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1856 return HeapRegion::max_region_size(); 1857 } 1858 1859 void G1CollectedHeap::post_initialize() { 1860 CollectedHeap::post_initialize(); 1861 ref_processing_init(); 1862 } 1863 1864 void G1CollectedHeap::ref_processing_init() { 1865 // Reference processing in G1 currently works as follows: 1866 // 1867 // * There are two reference processor instances. One is 1868 // used to record and process discovered references 1869 // during concurrent marking; the other is used to 1870 // record and process references during STW pauses 1871 // (both full and incremental). 1872 // * Both ref processors need to 'span' the entire heap as 1873 // the regions in the collection set may be dotted around. 1874 // 1875 // * For the concurrent marking ref processor: 1876 // * Reference discovery is enabled at initial marking. 1877 // * Reference discovery is disabled and the discovered 1878 // references processed etc during remarking. 1879 // * Reference discovery is MT (see below). 1880 // * Reference discovery requires a barrier (see below). 1881 // * Reference processing may or may not be MT 1882 // (depending on the value of ParallelRefProcEnabled 1883 // and ParallelGCThreads). 1884 // * A full GC disables reference discovery by the CM 1885 // ref processor and abandons any entries on it's 1886 // discovered lists. 1887 // 1888 // * For the STW processor: 1889 // * Non MT discovery is enabled at the start of a full GC. 1890 // * Processing and enqueueing during a full GC is non-MT. 1891 // * During a full GC, references are processed after marking. 1892 // 1893 // * Discovery (may or may not be MT) is enabled at the start 1894 // of an incremental evacuation pause. 1895 // * References are processed near the end of a STW evacuation pause. 1896 // * For both types of GC: 1897 // * Discovery is atomic - i.e. not concurrent. 1898 // * Reference discovery will not need a barrier. 1899 1900 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1901 1902 // Concurrent Mark ref processor 1903 _ref_processor_cm = 1904 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1905 mt_processing, // mt processing 1906 ParallelGCThreads, // degree of mt processing 1907 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1908 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1909 false, // Reference discovery is not atomic 1910 &_is_alive_closure_cm, // is alive closure 1911 true); // allow changes to number of processing threads 1912 1913 // STW ref processor 1914 _ref_processor_stw = 1915 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1916 mt_processing, // mt processing 1917 ParallelGCThreads, // degree of mt processing 1918 (ParallelGCThreads > 1), // mt discovery 1919 ParallelGCThreads, // degree of mt discovery 1920 true, // Reference discovery is atomic 1921 &_is_alive_closure_stw, // is alive closure 1922 true); // allow changes to number of processing threads 1923 } 1924 1925 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1926 return _collector_policy; 1927 } 1928 1929 G1CollectorPolicy* G1CollectedHeap::g1_collector_policy() const { 1930 return _collector_policy; 1931 } 1932 1933 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1934 return &_soft_ref_policy; 1935 } 1936 1937 size_t G1CollectedHeap::capacity() const { 1938 return _hrm->length() * HeapRegion::GrainBytes; 1939 } 1940 1941 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1942 return _hrm->total_free_bytes(); 1943 } 1944 1945 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1946 _hot_card_cache->drain(cl, worker_i); 1947 } 1948 1949 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1950 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1951 size_t n_completed_buffers = 0; 1952 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1953 n_completed_buffers++; 1954 } 1955 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1956 dcqs.clear_n_completed_buffers(); 1957 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1958 } 1959 1960 // Computes the sum of the storage used by the various regions. 1961 size_t G1CollectedHeap::used() const { 1962 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1963 if (_archive_allocator != NULL) { 1964 result += _archive_allocator->used(); 1965 } 1966 return result; 1967 } 1968 1969 size_t G1CollectedHeap::used_unlocked() const { 1970 return _summary_bytes_used; 1971 } 1972 1973 class SumUsedClosure: public HeapRegionClosure { 1974 size_t _used; 1975 public: 1976 SumUsedClosure() : _used(0) {} 1977 bool do_heap_region(HeapRegion* r) { 1978 _used += r->used(); 1979 return false; 1980 } 1981 size_t result() { return _used; } 1982 }; 1983 1984 size_t G1CollectedHeap::recalculate_used() const { 1985 SumUsedClosure blk; 1986 heap_region_iterate(&blk); 1987 return blk.result(); 1988 } 1989 1990 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1991 switch (cause) { 1992 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1993 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1994 case GCCause::_wb_conc_mark: return true; 1995 default : return false; 1996 } 1997 } 1998 1999 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 2000 switch (cause) { 2001 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 2002 case GCCause::_g1_humongous_allocation: return true; 2003 default: return is_user_requested_concurrent_full_gc(cause); 2004 } 2005 } 2006 2007 #ifndef PRODUCT 2008 void G1CollectedHeap::allocate_dummy_regions() { 2009 // Let's fill up most of the region 2010 size_t word_size = HeapRegion::GrainWords - 1024; 2011 // And as a result the region we'll allocate will be humongous. 2012 guarantee(is_humongous(word_size), "sanity"); 2013 2014 // _filler_array_max_size is set to humongous object threshold 2015 // but temporarily change it to use CollectedHeap::fill_with_object(). 2016 SizeTFlagSetting fs(_filler_array_max_size, word_size); 2017 2018 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 2019 // Let's use the existing mechanism for the allocation 2020 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 2021 if (dummy_obj != NULL) { 2022 MemRegion mr(dummy_obj, word_size); 2023 CollectedHeap::fill_with_object(mr); 2024 } else { 2025 // If we can't allocate once, we probably cannot allocate 2026 // again. Let's get out of the loop. 2027 break; 2028 } 2029 } 2030 } 2031 #endif // !PRODUCT 2032 2033 void G1CollectedHeap::increment_old_marking_cycles_started() { 2034 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2035 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2036 "Wrong marking cycle count (started: %d, completed: %d)", 2037 _old_marking_cycles_started, _old_marking_cycles_completed); 2038 2039 _old_marking_cycles_started++; 2040 } 2041 2042 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2043 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2044 2045 // We assume that if concurrent == true, then the caller is a 2046 // concurrent thread that was joined the Suspendible Thread 2047 // Set. If there's ever a cheap way to check this, we should add an 2048 // assert here. 2049 2050 // Given that this method is called at the end of a Full GC or of a 2051 // concurrent cycle, and those can be nested (i.e., a Full GC can 2052 // interrupt a concurrent cycle), the number of full collections 2053 // completed should be either one (in the case where there was no 2054 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2055 // behind the number of full collections started. 2056 2057 // This is the case for the inner caller, i.e. a Full GC. 2058 assert(concurrent || 2059 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2060 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2061 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2062 "is inconsistent with _old_marking_cycles_completed = %u", 2063 _old_marking_cycles_started, _old_marking_cycles_completed); 2064 2065 // This is the case for the outer caller, i.e. the concurrent cycle. 2066 assert(!concurrent || 2067 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2068 "for outer caller (concurrent cycle): " 2069 "_old_marking_cycles_started = %u " 2070 "is inconsistent with _old_marking_cycles_completed = %u", 2071 _old_marking_cycles_started, _old_marking_cycles_completed); 2072 2073 _old_marking_cycles_completed += 1; 2074 2075 // We need to clear the "in_progress" flag in the CM thread before 2076 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2077 // is set) so that if a waiter requests another System.gc() it doesn't 2078 // incorrectly see that a marking cycle is still in progress. 2079 if (concurrent) { 2080 _cm_thread->set_idle(); 2081 } 2082 2083 // This notify_all() will ensure that a thread that called 2084 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2085 // and it's waiting for a full GC to finish will be woken up. It is 2086 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2087 FullGCCount_lock->notify_all(); 2088 } 2089 2090 void G1CollectedHeap::collect(GCCause::Cause cause) { 2091 assert_heap_not_locked(); 2092 2093 uint gc_count_before; 2094 uint old_marking_count_before; 2095 uint full_gc_count_before; 2096 bool retry_gc; 2097 2098 do { 2099 retry_gc = false; 2100 2101 { 2102 MutexLocker ml(Heap_lock); 2103 2104 // Read the GC count while holding the Heap_lock 2105 gc_count_before = total_collections(); 2106 full_gc_count_before = total_full_collections(); 2107 old_marking_count_before = _old_marking_cycles_started; 2108 } 2109 2110 if (should_do_concurrent_full_gc(cause)) { 2111 // Schedule an initial-mark evacuation pause that will start a 2112 // concurrent cycle. We're setting word_size to 0 which means that 2113 // we are not requesting a post-GC allocation. 2114 VM_G1CollectForAllocation op(0, /* word_size */ 2115 gc_count_before, 2116 cause, 2117 true, /* should_initiate_conc_mark */ 2118 g1_policy()->max_pause_time_ms()); 2119 VMThread::execute(&op); 2120 if (!op.pause_succeeded()) { 2121 if (old_marking_count_before == _old_marking_cycles_started) { 2122 retry_gc = op.should_retry_gc(); 2123 } else { 2124 // A Full GC happened while we were trying to schedule the 2125 // initial-mark GC. No point in starting a new cycle given 2126 // that the whole heap was collected anyway. 2127 } 2128 2129 if (retry_gc) { 2130 if (GCLocker::is_active_and_needs_gc()) { 2131 GCLocker::stall_until_clear(); 2132 } 2133 } 2134 } 2135 } else { 2136 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2137 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2138 2139 // Schedule a standard evacuation pause. We're setting word_size 2140 // to 0 which means that we are not requesting a post-GC allocation. 2141 VM_G1CollectForAllocation op(0, /* word_size */ 2142 gc_count_before, 2143 cause, 2144 false, /* should_initiate_conc_mark */ 2145 g1_policy()->max_pause_time_ms()); 2146 VMThread::execute(&op); 2147 } else { 2148 // Schedule a Full GC. 2149 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2150 VMThread::execute(&op); 2151 } 2152 } 2153 } while (retry_gc); 2154 } 2155 2156 bool G1CollectedHeap::is_in(const void* p) const { 2157 if (_hrm->reserved().contains(p)) { 2158 // Given that we know that p is in the reserved space, 2159 // heap_region_containing() should successfully 2160 // return the containing region. 2161 HeapRegion* hr = heap_region_containing(p); 2162 return hr->is_in(p); 2163 } else { 2164 return false; 2165 } 2166 } 2167 2168 #ifdef ASSERT 2169 bool G1CollectedHeap::is_in_exact(const void* p) const { 2170 bool contains = reserved_region().contains(p); 2171 bool available = _hrm->is_available(addr_to_region((HeapWord*)p)); 2172 if (contains && available) { 2173 return true; 2174 } else { 2175 return false; 2176 } 2177 } 2178 #endif 2179 2180 // Iteration functions. 2181 2182 // Iterates an ObjectClosure over all objects within a HeapRegion. 2183 2184 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2185 ObjectClosure* _cl; 2186 public: 2187 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2188 bool do_heap_region(HeapRegion* r) { 2189 if (!r->is_continues_humongous()) { 2190 r->object_iterate(_cl); 2191 } 2192 return false; 2193 } 2194 }; 2195 2196 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2197 IterateObjectClosureRegionClosure blk(cl); 2198 heap_region_iterate(&blk); 2199 } 2200 2201 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2202 _hrm->iterate(cl); 2203 } 2204 2205 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2206 HeapRegionClaimer *hrclaimer, 2207 uint worker_id) const { 2208 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2209 } 2210 2211 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2212 HeapRegionClaimer *hrclaimer) const { 2213 _hrm->par_iterate(cl, hrclaimer, 0); 2214 } 2215 2216 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2217 _collection_set.iterate(cl); 2218 } 2219 2220 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2221 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2222 } 2223 2224 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2225 HeapRegion* hr = heap_region_containing(addr); 2226 return hr->block_start(addr); 2227 } 2228 2229 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2230 HeapRegion* hr = heap_region_containing(addr); 2231 return hr->block_size(addr); 2232 } 2233 2234 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2235 HeapRegion* hr = heap_region_containing(addr); 2236 return hr->block_is_obj(addr); 2237 } 2238 2239 bool G1CollectedHeap::supports_tlab_allocation() const { 2240 return true; 2241 } 2242 2243 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2244 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2245 } 2246 2247 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2248 return _eden.length() * HeapRegion::GrainBytes; 2249 } 2250 2251 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2252 // must be equal to the humongous object limit. 2253 size_t G1CollectedHeap::max_tlab_size() const { 2254 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2255 } 2256 2257 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2258 return _allocator->unsafe_max_tlab_alloc(); 2259 } 2260 2261 size_t G1CollectedHeap::max_capacity() const { 2262 return _hrm->max_expandable_length() * HeapRegion::GrainBytes; 2263 } 2264 2265 size_t G1CollectedHeap::max_reserved_capacity() const { 2266 return _hrm->max_length() * HeapRegion::GrainBytes; 2267 } 2268 2269 jlong G1CollectedHeap::millis_since_last_gc() { 2270 // See the notes in GenCollectedHeap::millis_since_last_gc() 2271 // for more information about the implementation. 2272 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2273 _g1_policy->collection_pause_end_millis(); 2274 if (ret_val < 0) { 2275 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2276 ". returning zero instead.", ret_val); 2277 return 0; 2278 } 2279 return ret_val; 2280 } 2281 2282 void G1CollectedHeap::deduplicate_string(oop str) { 2283 assert(java_lang_String::is_instance(str), "invariant"); 2284 2285 if (G1StringDedup::is_enabled()) { 2286 G1StringDedup::deduplicate(str); 2287 } 2288 } 2289 2290 void G1CollectedHeap::prepare_for_verify() { 2291 _verifier->prepare_for_verify(); 2292 } 2293 2294 void G1CollectedHeap::verify(VerifyOption vo) { 2295 _verifier->verify(vo); 2296 } 2297 2298 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2299 return true; 2300 } 2301 2302 const char* const* G1CollectedHeap::concurrent_phases() const { 2303 return _cm_thread->concurrent_phases(); 2304 } 2305 2306 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2307 return _cm_thread->request_concurrent_phase(phase); 2308 } 2309 2310 class PrintRegionClosure: public HeapRegionClosure { 2311 outputStream* _st; 2312 public: 2313 PrintRegionClosure(outputStream* st) : _st(st) {} 2314 bool do_heap_region(HeapRegion* r) { 2315 r->print_on(_st); 2316 return false; 2317 } 2318 }; 2319 2320 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2321 const HeapRegion* hr, 2322 const VerifyOption vo) const { 2323 switch (vo) { 2324 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2325 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2326 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2327 default: ShouldNotReachHere(); 2328 } 2329 return false; // keep some compilers happy 2330 } 2331 2332 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2333 const VerifyOption vo) const { 2334 switch (vo) { 2335 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2336 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2337 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2338 default: ShouldNotReachHere(); 2339 } 2340 return false; // keep some compilers happy 2341 } 2342 2343 void G1CollectedHeap::print_heap_regions() const { 2344 LogTarget(Trace, gc, heap, region) lt; 2345 if (lt.is_enabled()) { 2346 LogStream ls(lt); 2347 print_regions_on(&ls); 2348 } 2349 } 2350 2351 void G1CollectedHeap::print_on(outputStream* st) const { 2352 st->print(" %-20s", "garbage-first heap"); 2353 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2354 capacity()/K, used_unlocked()/K); 2355 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2356 p2i(_hrm->reserved().start()), 2357 p2i(_hrm->reserved().end())); 2358 st->cr(); 2359 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2360 uint young_regions = young_regions_count(); 2361 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2362 (size_t) young_regions * HeapRegion::GrainBytes / K); 2363 uint survivor_regions = survivor_regions_count(); 2364 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2365 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2366 st->cr(); 2367 MetaspaceUtils::print_on(st); 2368 } 2369 2370 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2371 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2372 "HS=humongous(starts), HC=humongous(continues), " 2373 "CS=collection set, F=free, A=archive, " 2374 "TAMS=top-at-mark-start (previous, next)"); 2375 PrintRegionClosure blk(st); 2376 heap_region_iterate(&blk); 2377 } 2378 2379 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2380 print_on(st); 2381 2382 // Print the per-region information. 2383 print_regions_on(st); 2384 } 2385 2386 void G1CollectedHeap::print_on_error(outputStream* st) const { 2387 this->CollectedHeap::print_on_error(st); 2388 2389 if (_cm != NULL) { 2390 st->cr(); 2391 _cm->print_on_error(st); 2392 } 2393 } 2394 2395 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2396 workers()->print_worker_threads_on(st); 2397 _cm_thread->print_on(st); 2398 st->cr(); 2399 _cm->print_worker_threads_on(st); 2400 _cr->print_threads_on(st); 2401 _young_gen_sampling_thread->print_on(st); 2402 if (G1StringDedup::is_enabled()) { 2403 G1StringDedup::print_worker_threads_on(st); 2404 } 2405 } 2406 2407 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2408 workers()->threads_do(tc); 2409 tc->do_thread(_cm_thread); 2410 _cm->threads_do(tc); 2411 _cr->threads_do(tc); 2412 tc->do_thread(_young_gen_sampling_thread); 2413 if (G1StringDedup::is_enabled()) { 2414 G1StringDedup::threads_do(tc); 2415 } 2416 } 2417 2418 void G1CollectedHeap::print_tracing_info() const { 2419 g1_rem_set()->print_summary_info(); 2420 concurrent_mark()->print_summary_info(); 2421 } 2422 2423 #ifndef PRODUCT 2424 // Helpful for debugging RSet issues. 2425 2426 class PrintRSetsClosure : public HeapRegionClosure { 2427 private: 2428 const char* _msg; 2429 size_t _occupied_sum; 2430 2431 public: 2432 bool do_heap_region(HeapRegion* r) { 2433 HeapRegionRemSet* hrrs = r->rem_set(); 2434 size_t occupied = hrrs->occupied(); 2435 _occupied_sum += occupied; 2436 2437 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2438 if (occupied == 0) { 2439 tty->print_cr(" RSet is empty"); 2440 } else { 2441 hrrs->print(); 2442 } 2443 tty->print_cr("----------"); 2444 return false; 2445 } 2446 2447 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2448 tty->cr(); 2449 tty->print_cr("========================================"); 2450 tty->print_cr("%s", msg); 2451 tty->cr(); 2452 } 2453 2454 ~PrintRSetsClosure() { 2455 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2456 tty->print_cr("========================================"); 2457 tty->cr(); 2458 } 2459 }; 2460 2461 void G1CollectedHeap::print_cset_rsets() { 2462 PrintRSetsClosure cl("Printing CSet RSets"); 2463 collection_set_iterate(&cl); 2464 } 2465 2466 void G1CollectedHeap::print_all_rsets() { 2467 PrintRSetsClosure cl("Printing All RSets");; 2468 heap_region_iterate(&cl); 2469 } 2470 #endif // PRODUCT 2471 2472 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2473 2474 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2475 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2476 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2477 2478 size_t eden_capacity_bytes = 2479 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2480 2481 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2482 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2483 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2484 } 2485 2486 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2487 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2488 stats->unused(), stats->used(), stats->region_end_waste(), 2489 stats->regions_filled(), stats->direct_allocated(), 2490 stats->failure_used(), stats->failure_waste()); 2491 } 2492 2493 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2494 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2495 gc_tracer->report_gc_heap_summary(when, heap_summary); 2496 2497 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2498 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2499 } 2500 2501 G1CollectedHeap* G1CollectedHeap::heap() { 2502 CollectedHeap* heap = Universe::heap(); 2503 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2504 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2505 return (G1CollectedHeap*)heap; 2506 } 2507 2508 void G1CollectedHeap::gc_prologue(bool full) { 2509 // always_do_update_barrier = false; 2510 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2511 2512 // This summary needs to be printed before incrementing total collections. 2513 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2514 2515 // Update common counters. 2516 increment_total_collections(full /* full gc */); 2517 if (full) { 2518 increment_old_marking_cycles_started(); 2519 } 2520 2521 // Fill TLAB's and such 2522 double start = os::elapsedTime(); 2523 ensure_parsability(true); 2524 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2525 } 2526 2527 void G1CollectedHeap::gc_epilogue(bool full) { 2528 // Update common counters. 2529 if (full) { 2530 // Update the number of full collections that have been completed. 2531 increment_old_marking_cycles_completed(false /* concurrent */); 2532 // Now we know the target length of young list. So adjust the heap to provision that many regions on dram. 2533 if (is_hetero_heap()) { 2534 static_cast<HeterogeneousHeapRegionManager*>(hrm())->adjust_dram_regions((uint)g1_policy()->young_list_target_length(), workers()); 2535 } 2536 } 2537 2538 // We are at the end of the GC. Total collections has already been increased. 2539 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2540 2541 // FIXME: what is this about? 2542 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2543 // is set. 2544 #if COMPILER2_OR_JVMCI 2545 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2546 #endif 2547 // always_do_update_barrier = true; 2548 2549 double start = os::elapsedTime(); 2550 resize_all_tlabs(); 2551 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2552 2553 MemoryService::track_memory_usage(); 2554 // We have just completed a GC. Update the soft reference 2555 // policy with the new heap occupancy 2556 Universe::update_heap_info_at_gc(); 2557 } 2558 2559 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2560 uint gc_count_before, 2561 bool* succeeded, 2562 GCCause::Cause gc_cause) { 2563 assert_heap_not_locked_and_not_at_safepoint(); 2564 VM_G1CollectForAllocation op(word_size, 2565 gc_count_before, 2566 gc_cause, 2567 false, /* should_initiate_conc_mark */ 2568 g1_policy()->max_pause_time_ms()); 2569 VMThread::execute(&op); 2570 2571 HeapWord* result = op.result(); 2572 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2573 assert(result == NULL || ret_succeeded, 2574 "the result should be NULL if the VM did not succeed"); 2575 *succeeded = ret_succeeded; 2576 2577 assert_heap_not_locked(); 2578 return result; 2579 } 2580 2581 void G1CollectedHeap::do_concurrent_mark() { 2582 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2583 if (!_cm_thread->in_progress()) { 2584 _cm_thread->set_started(); 2585 CGC_lock->notify(); 2586 } 2587 } 2588 2589 size_t G1CollectedHeap::pending_card_num() { 2590 size_t extra_cards = 0; 2591 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2592 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2593 extra_cards += dcq.size(); 2594 } 2595 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2596 size_t buffer_size = dcqs.buffer_size(); 2597 size_t buffer_num = dcqs.completed_buffers_num(); 2598 2599 return buffer_size * buffer_num + extra_cards; 2600 } 2601 2602 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2603 // We don't nominate objects with many remembered set entries, on 2604 // the assumption that such objects are likely still live. 2605 HeapRegionRemSet* rem_set = r->rem_set(); 2606 2607 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2608 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2609 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2610 } 2611 2612 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2613 private: 2614 size_t _total_humongous; 2615 size_t _candidate_humongous; 2616 2617 DirtyCardQueue _dcq; 2618 2619 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2620 assert(region->is_starts_humongous(), "Must start a humongous object"); 2621 2622 oop obj = oop(region->bottom()); 2623 2624 // Dead objects cannot be eager reclaim candidates. Due to class 2625 // unloading it is unsafe to query their classes so we return early. 2626 if (g1h->is_obj_dead(obj, region)) { 2627 return false; 2628 } 2629 2630 // If we do not have a complete remembered set for the region, then we can 2631 // not be sure that we have all references to it. 2632 if (!region->rem_set()->is_complete()) { 2633 return false; 2634 } 2635 // Candidate selection must satisfy the following constraints 2636 // while concurrent marking is in progress: 2637 // 2638 // * In order to maintain SATB invariants, an object must not be 2639 // reclaimed if it was allocated before the start of marking and 2640 // has not had its references scanned. Such an object must have 2641 // its references (including type metadata) scanned to ensure no 2642 // live objects are missed by the marking process. Objects 2643 // allocated after the start of concurrent marking don't need to 2644 // be scanned. 2645 // 2646 // * An object must not be reclaimed if it is on the concurrent 2647 // mark stack. Objects allocated after the start of concurrent 2648 // marking are never pushed on the mark stack. 2649 // 2650 // Nominating only objects allocated after the start of concurrent 2651 // marking is sufficient to meet both constraints. This may miss 2652 // some objects that satisfy the constraints, but the marking data 2653 // structures don't support efficiently performing the needed 2654 // additional tests or scrubbing of the mark stack. 2655 // 2656 // However, we presently only nominate is_typeArray() objects. 2657 // A humongous object containing references induces remembered 2658 // set entries on other regions. In order to reclaim such an 2659 // object, those remembered sets would need to be cleaned up. 2660 // 2661 // We also treat is_typeArray() objects specially, allowing them 2662 // to be reclaimed even if allocated before the start of 2663 // concurrent mark. For this we rely on mark stack insertion to 2664 // exclude is_typeArray() objects, preventing reclaiming an object 2665 // that is in the mark stack. We also rely on the metadata for 2666 // such objects to be built-in and so ensured to be kept live. 2667 // Frequent allocation and drop of large binary blobs is an 2668 // important use case for eager reclaim, and this special handling 2669 // may reduce needed headroom. 2670 2671 return obj->is_typeArray() && 2672 g1h->is_potential_eager_reclaim_candidate(region); 2673 } 2674 2675 public: 2676 RegisterHumongousWithInCSetFastTestClosure() 2677 : _total_humongous(0), 2678 _candidate_humongous(0), 2679 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2680 } 2681 2682 virtual bool do_heap_region(HeapRegion* r) { 2683 if (!r->is_starts_humongous()) { 2684 return false; 2685 } 2686 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2687 2688 bool is_candidate = humongous_region_is_candidate(g1h, r); 2689 uint rindex = r->hrm_index(); 2690 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2691 if (is_candidate) { 2692 _candidate_humongous++; 2693 g1h->register_humongous_region_with_cset(rindex); 2694 // Is_candidate already filters out humongous object with large remembered sets. 2695 // If we have a humongous object with a few remembered sets, we simply flush these 2696 // remembered set entries into the DCQS. That will result in automatic 2697 // re-evaluation of their remembered set entries during the following evacuation 2698 // phase. 2699 if (!r->rem_set()->is_empty()) { 2700 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2701 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2702 G1CardTable* ct = g1h->card_table(); 2703 HeapRegionRemSetIterator hrrs(r->rem_set()); 2704 size_t card_index; 2705 while (hrrs.has_next(card_index)) { 2706 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2707 // The remembered set might contain references to already freed 2708 // regions. Filter out such entries to avoid failing card table 2709 // verification. 2710 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2711 if (*card_ptr != G1CardTable::dirty_card_val()) { 2712 *card_ptr = G1CardTable::dirty_card_val(); 2713 _dcq.enqueue(card_ptr); 2714 } 2715 } 2716 } 2717 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2718 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2719 hrrs.n_yielded(), r->rem_set()->occupied()); 2720 // We should only clear the card based remembered set here as we will not 2721 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2722 // (and probably never) we do not enter this path if there are other kind of 2723 // remembered sets for this region. 2724 r->rem_set()->clear_locked(true /* only_cardset */); 2725 // Clear_locked() above sets the state to Empty. However we want to continue 2726 // collecting remembered set entries for humongous regions that were not 2727 // reclaimed. 2728 r->rem_set()->set_state_complete(); 2729 } 2730 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2731 } 2732 _total_humongous++; 2733 2734 return false; 2735 } 2736 2737 size_t total_humongous() const { return _total_humongous; } 2738 size_t candidate_humongous() const { return _candidate_humongous; } 2739 2740 void flush_rem_set_entries() { _dcq.flush(); } 2741 }; 2742 2743 void G1CollectedHeap::register_humongous_regions_with_cset() { 2744 if (!G1EagerReclaimHumongousObjects) { 2745 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2746 return; 2747 } 2748 double time = os::elapsed_counter(); 2749 2750 // Collect reclaim candidate information and register candidates with cset. 2751 RegisterHumongousWithInCSetFastTestClosure cl; 2752 heap_region_iterate(&cl); 2753 2754 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2755 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2756 cl.total_humongous(), 2757 cl.candidate_humongous()); 2758 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2759 2760 // Finally flush all remembered set entries to re-check into the global DCQS. 2761 cl.flush_rem_set_entries(); 2762 } 2763 2764 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2765 public: 2766 bool do_heap_region(HeapRegion* hr) { 2767 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2768 hr->verify_rem_set(); 2769 } 2770 return false; 2771 } 2772 }; 2773 2774 uint G1CollectedHeap::num_task_queues() const { 2775 return _task_queues->size(); 2776 } 2777 2778 #if TASKQUEUE_STATS 2779 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2780 st->print_raw_cr("GC Task Stats"); 2781 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2782 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2783 } 2784 2785 void G1CollectedHeap::print_taskqueue_stats() const { 2786 if (!log_is_enabled(Trace, gc, task, stats)) { 2787 return; 2788 } 2789 Log(gc, task, stats) log; 2790 ResourceMark rm; 2791 LogStream ls(log.trace()); 2792 outputStream* st = &ls; 2793 2794 print_taskqueue_stats_hdr(st); 2795 2796 TaskQueueStats totals; 2797 const uint n = num_task_queues(); 2798 for (uint i = 0; i < n; ++i) { 2799 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2800 totals += task_queue(i)->stats; 2801 } 2802 st->print_raw("tot "); totals.print(st); st->cr(); 2803 2804 DEBUG_ONLY(totals.verify()); 2805 } 2806 2807 void G1CollectedHeap::reset_taskqueue_stats() { 2808 const uint n = num_task_queues(); 2809 for (uint i = 0; i < n; ++i) { 2810 task_queue(i)->stats.reset(); 2811 } 2812 } 2813 #endif // TASKQUEUE_STATS 2814 2815 void G1CollectedHeap::wait_for_root_region_scanning() { 2816 double scan_wait_start = os::elapsedTime(); 2817 // We have to wait until the CM threads finish scanning the 2818 // root regions as it's the only way to ensure that all the 2819 // objects on them have been correctly scanned before we start 2820 // moving them during the GC. 2821 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2822 double wait_time_ms = 0.0; 2823 if (waited) { 2824 double scan_wait_end = os::elapsedTime(); 2825 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2826 } 2827 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2828 } 2829 2830 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2831 private: 2832 G1HRPrinter* _hr_printer; 2833 public: 2834 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2835 2836 virtual bool do_heap_region(HeapRegion* r) { 2837 _hr_printer->cset(r); 2838 return false; 2839 } 2840 }; 2841 2842 void G1CollectedHeap::start_new_collection_set() { 2843 collection_set()->start_incremental_building(); 2844 2845 clear_cset_fast_test(); 2846 2847 guarantee(_eden.length() == 0, "eden should have been cleared"); 2848 g1_policy()->transfer_survivors_to_cset(survivor()); 2849 } 2850 2851 bool 2852 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2853 assert_at_safepoint_on_vm_thread(); 2854 guarantee(!is_gc_active(), "collection is not reentrant"); 2855 2856 if (GCLocker::check_active_before_gc()) { 2857 return false; 2858 } 2859 2860 _gc_timer_stw->register_gc_start(); 2861 2862 GCIdMark gc_id_mark; 2863 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2864 2865 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2866 ResourceMark rm; 2867 2868 g1_policy()->note_gc_start(); 2869 2870 wait_for_root_region_scanning(); 2871 2872 print_heap_before_gc(); 2873 print_heap_regions(); 2874 trace_heap_before_gc(_gc_tracer_stw); 2875 2876 _verifier->verify_region_sets_optional(); 2877 _verifier->verify_dirty_young_regions(); 2878 2879 // We should not be doing initial mark unless the conc mark thread is running 2880 if (!_cm_thread->should_terminate()) { 2881 // This call will decide whether this pause is an initial-mark 2882 // pause. If it is, in_initial_mark_gc() will return true 2883 // for the duration of this pause. 2884 g1_policy()->decide_on_conc_mark_initiation(); 2885 } 2886 2887 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2888 assert(!collector_state()->in_initial_mark_gc() || 2889 collector_state()->in_young_only_phase(), "sanity"); 2890 2891 // We also do not allow mixed GCs during marking. 2892 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2893 2894 // Record whether this pause is an initial mark. When the current 2895 // thread has completed its logging output and it's safe to signal 2896 // the CM thread, the flag's value in the policy has been reset. 2897 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2898 2899 // Inner scope for scope based logging, timers, and stats collection 2900 { 2901 EvacuationInfo evacuation_info; 2902 2903 if (collector_state()->in_initial_mark_gc()) { 2904 // We are about to start a marking cycle, so we increment the 2905 // full collection counter. 2906 increment_old_marking_cycles_started(); 2907 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2908 } 2909 2910 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2911 2912 GCTraceCPUTime tcpu; 2913 2914 G1HeapVerifier::G1VerifyType verify_type; 2915 FormatBuffer<> gc_string("Pause Young "); 2916 if (collector_state()->in_initial_mark_gc()) { 2917 gc_string.append("(Concurrent Start)"); 2918 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2919 } else if (collector_state()->in_young_only_phase()) { 2920 if (collector_state()->in_young_gc_before_mixed()) { 2921 gc_string.append("(Prepare Mixed)"); 2922 } else { 2923 gc_string.append("(Normal)"); 2924 } 2925 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2926 } else { 2927 gc_string.append("(Mixed)"); 2928 verify_type = G1HeapVerifier::G1VerifyMixed; 2929 } 2930 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2931 2932 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2933 workers()->active_workers(), 2934 Threads::number_of_non_daemon_threads()); 2935 active_workers = workers()->update_active_workers(active_workers); 2936 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2937 2938 G1MonitoringScope ms(g1mm(), 2939 false /* full_gc */, 2940 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2941 2942 G1HeapTransition heap_transition(this); 2943 size_t heap_used_bytes_before_gc = used(); 2944 2945 // Don't dynamically change the number of GC threads this early. A value of 2946 // 0 is used to indicate serial work. When parallel work is done, 2947 // it will be set. 2948 2949 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2950 IsGCActiveMark x; 2951 2952 gc_prologue(false); 2953 2954 if (VerifyRememberedSets) { 2955 log_info(gc, verify)("[Verifying RemSets before GC]"); 2956 VerifyRegionRemSetClosure v_cl; 2957 heap_region_iterate(&v_cl); 2958 } 2959 2960 _verifier->verify_before_gc(verify_type); 2961 2962 _verifier->check_bitmaps("GC Start"); 2963 2964 #if COMPILER2_OR_JVMCI 2965 DerivedPointerTable::clear(); 2966 #endif 2967 2968 // Please see comment in g1CollectedHeap.hpp and 2969 // G1CollectedHeap::ref_processing_init() to see how 2970 // reference processing currently works in G1. 2971 2972 // Enable discovery in the STW reference processor 2973 _ref_processor_stw->enable_discovery(); 2974 2975 { 2976 // We want to temporarily turn off discovery by the 2977 // CM ref processor, if necessary, and turn it back on 2978 // on again later if we do. Using a scoped 2979 // NoRefDiscovery object will do this. 2980 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 2981 2982 // Forget the current alloc region (we might even choose it to be part 2983 // of the collection set!). 2984 _allocator->release_mutator_alloc_region(); 2985 2986 // This timing is only used by the ergonomics to handle our pause target. 2987 // It is unclear why this should not include the full pause. We will 2988 // investigate this in CR 7178365. 2989 // 2990 // Preserving the old comment here if that helps the investigation: 2991 // 2992 // The elapsed time induced by the start time below deliberately elides 2993 // the possible verification above. 2994 double sample_start_time_sec = os::elapsedTime(); 2995 2996 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2997 2998 if (collector_state()->in_initial_mark_gc()) { 2999 concurrent_mark()->pre_initial_mark(); 3000 } 3001 3002 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 3003 3004 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 3005 3006 // Make sure the remembered sets are up to date. This needs to be 3007 // done before register_humongous_regions_with_cset(), because the 3008 // remembered sets are used there to choose eager reclaim candidates. 3009 // If the remembered sets are not up to date we might miss some 3010 // entries that need to be handled. 3011 g1_rem_set()->cleanupHRRS(); 3012 3013 register_humongous_regions_with_cset(); 3014 3015 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 3016 3017 // We call this after finalize_cset() to 3018 // ensure that the CSet has been finalized. 3019 _cm->verify_no_cset_oops(); 3020 3021 if (_hr_printer.is_active()) { 3022 G1PrintCollectionSetClosure cl(&_hr_printer); 3023 _collection_set.iterate(&cl); 3024 } 3025 3026 // Initialize the GC alloc regions. 3027 _allocator->init_gc_alloc_regions(evacuation_info); 3028 3029 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 3030 pre_evacuate_collection_set(); 3031 3032 // Actually do the work... 3033 evacuate_collection_set(&per_thread_states); 3034 3035 post_evacuate_collection_set(evacuation_info, &per_thread_states); 3036 3037 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3038 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3039 3040 eagerly_reclaim_humongous_regions(); 3041 3042 record_obj_copy_mem_stats(); 3043 _survivor_evac_stats.adjust_desired_plab_sz(); 3044 _old_evac_stats.adjust_desired_plab_sz(); 3045 3046 double start = os::elapsedTime(); 3047 start_new_collection_set(); 3048 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3049 3050 if (evacuation_failed()) { 3051 double recalculate_used_start = os::elapsedTime(); 3052 set_used(recalculate_used()); 3053 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3054 3055 if (_archive_allocator != NULL) { 3056 _archive_allocator->clear_used(); 3057 } 3058 for (uint i = 0; i < ParallelGCThreads; i++) { 3059 if (_evacuation_failed_info_array[i].has_failed()) { 3060 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3061 } 3062 } 3063 } else { 3064 // The "used" of the the collection set have already been subtracted 3065 // when they were freed. Add in the bytes evacuated. 3066 increase_used(g1_policy()->bytes_copied_during_gc()); 3067 } 3068 3069 if (collector_state()->in_initial_mark_gc()) { 3070 // We have to do this before we notify the CM threads that 3071 // they can start working to make sure that all the 3072 // appropriate initialization is done on the CM object. 3073 concurrent_mark()->post_initial_mark(); 3074 // Note that we don't actually trigger the CM thread at 3075 // this point. We do that later when we're sure that 3076 // the current thread has completed its logging output. 3077 } 3078 3079 allocate_dummy_regions(); 3080 3081 _allocator->init_mutator_alloc_region(); 3082 3083 { 3084 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3085 if (expand_bytes > 0) { 3086 size_t bytes_before = capacity(); 3087 // No need for an ergo logging here, 3088 // expansion_amount() does this when it returns a value > 0. 3089 double expand_ms; 3090 if (!expand(expand_bytes, _workers, &expand_ms)) { 3091 // We failed to expand the heap. Cannot do anything about it. 3092 } 3093 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3094 } 3095 } 3096 3097 // We redo the verification but now wrt to the new CSet which 3098 // has just got initialized after the previous CSet was freed. 3099 _cm->verify_no_cset_oops(); 3100 3101 // This timing is only used by the ergonomics to handle our pause target. 3102 // It is unclear why this should not include the full pause. We will 3103 // investigate this in CR 7178365. 3104 double sample_end_time_sec = os::elapsedTime(); 3105 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3106 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3107 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3108 3109 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3110 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3111 3112 if (VerifyRememberedSets) { 3113 log_info(gc, verify)("[Verifying RemSets after GC]"); 3114 VerifyRegionRemSetClosure v_cl; 3115 heap_region_iterate(&v_cl); 3116 } 3117 3118 _verifier->verify_after_gc(verify_type); 3119 _verifier->check_bitmaps("GC End"); 3120 3121 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3122 _ref_processor_stw->verify_no_references_recorded(); 3123 3124 // CM reference discovery will be re-enabled if necessary. 3125 } 3126 3127 #ifdef TRACESPINNING 3128 ParallelTaskTerminator::print_termination_counts(); 3129 #endif 3130 3131 gc_epilogue(false); 3132 } 3133 3134 // Print the remainder of the GC log output. 3135 if (evacuation_failed()) { 3136 log_info(gc)("To-space exhausted"); 3137 } 3138 3139 g1_policy()->print_phases(); 3140 heap_transition.print(); 3141 3142 // It is not yet to safe to tell the concurrent mark to 3143 // start as we have some optional output below. We don't want the 3144 // output from the concurrent mark thread interfering with this 3145 // logging output either. 3146 3147 _hrm->verify_optional(); 3148 _verifier->verify_region_sets_optional(); 3149 3150 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3151 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3152 3153 print_heap_after_gc(); 3154 print_heap_regions(); 3155 trace_heap_after_gc(_gc_tracer_stw); 3156 3157 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3158 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3159 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3160 // before any GC notifications are raised. 3161 g1mm()->update_sizes(); 3162 3163 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3164 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3165 _gc_timer_stw->register_gc_end(); 3166 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3167 } 3168 // It should now be safe to tell the concurrent mark thread to start 3169 // without its logging output interfering with the logging output 3170 // that came from the pause. 3171 3172 if (should_start_conc_mark) { 3173 // CAUTION: after the doConcurrentMark() call below, 3174 // the concurrent marking thread(s) could be running 3175 // concurrently with us. Make sure that anything after 3176 // this point does not assume that we are the only GC thread 3177 // running. Note: of course, the actual marking work will 3178 // not start until the safepoint itself is released in 3179 // SuspendibleThreadSet::desynchronize(). 3180 do_concurrent_mark(); 3181 } 3182 3183 return true; 3184 } 3185 3186 void G1CollectedHeap::remove_self_forwarding_pointers() { 3187 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3188 workers()->run_task(&rsfp_task); 3189 } 3190 3191 void G1CollectedHeap::restore_after_evac_failure() { 3192 double remove_self_forwards_start = os::elapsedTime(); 3193 3194 remove_self_forwarding_pointers(); 3195 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3196 _preserved_marks_set.restore(&task_executor); 3197 3198 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3199 } 3200 3201 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3202 if (!_evacuation_failed) { 3203 _evacuation_failed = true; 3204 } 3205 3206 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3207 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3208 } 3209 3210 bool G1ParEvacuateFollowersClosure::offer_termination() { 3211 EventGCPhaseParallel event; 3212 G1ParScanThreadState* const pss = par_scan_state(); 3213 start_term_time(); 3214 const bool res = terminator()->offer_termination(); 3215 end_term_time(); 3216 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3217 return res; 3218 } 3219 3220 void G1ParEvacuateFollowersClosure::do_void() { 3221 EventGCPhaseParallel event; 3222 G1ParScanThreadState* const pss = par_scan_state(); 3223 pss->trim_queue(); 3224 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy)); 3225 do { 3226 EventGCPhaseParallel event; 3227 pss->steal_and_trim_queue(queues()); 3228 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy)); 3229 } while (!offer_termination()); 3230 } 3231 3232 class G1ParTask : public AbstractGangTask { 3233 protected: 3234 G1CollectedHeap* _g1h; 3235 G1ParScanThreadStateSet* _pss; 3236 RefToScanQueueSet* _queues; 3237 G1RootProcessor* _root_processor; 3238 ParallelTaskTerminator _terminator; 3239 uint _n_workers; 3240 3241 public: 3242 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3243 : AbstractGangTask("G1 collection"), 3244 _g1h(g1h), 3245 _pss(per_thread_states), 3246 _queues(task_queues), 3247 _root_processor(root_processor), 3248 _terminator(n_workers, _queues), 3249 _n_workers(n_workers) 3250 {} 3251 3252 void work(uint worker_id) { 3253 if (worker_id >= _n_workers) return; // no work needed this round 3254 3255 double start_sec = os::elapsedTime(); 3256 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3257 3258 { 3259 ResourceMark rm; 3260 HandleMark hm; 3261 3262 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3263 3264 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3265 pss->set_ref_discoverer(rp); 3266 3267 double start_strong_roots_sec = os::elapsedTime(); 3268 3269 _root_processor->evacuate_roots(pss, worker_id); 3270 3271 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3272 // treating the nmethods visited to act as roots for concurrent marking. 3273 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3274 // objects copied by the current evacuation. 3275 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3276 3277 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3278 3279 double term_sec = 0.0; 3280 size_t evac_term_attempts = 0; 3281 { 3282 double start = os::elapsedTime(); 3283 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3284 evac.do_void(); 3285 3286 evac_term_attempts = evac.term_attempts(); 3287 term_sec = evac.term_time(); 3288 double elapsed_sec = os::elapsedTime() - start; 3289 3290 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3291 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3292 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3293 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3294 } 3295 3296 assert(pss->queue_is_empty(), "should be empty"); 3297 3298 if (log_is_enabled(Debug, gc, task, stats)) { 3299 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3300 size_t lab_waste; 3301 size_t lab_undo_waste; 3302 pss->waste(lab_waste, lab_undo_waste); 3303 _g1h->print_termination_stats(worker_id, 3304 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3305 strong_roots_sec * 1000.0, /* strong roots time */ 3306 term_sec * 1000.0, /* evac term time */ 3307 evac_term_attempts, /* evac term attempts */ 3308 lab_waste, /* alloc buffer waste */ 3309 lab_undo_waste /* undo waste */ 3310 ); 3311 } 3312 3313 // Close the inner scope so that the ResourceMark and HandleMark 3314 // destructors are executed here and are included as part of the 3315 // "GC Worker Time". 3316 } 3317 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3318 } 3319 }; 3320 3321 void G1CollectedHeap::print_termination_stats_hdr() { 3322 log_debug(gc, task, stats)("GC Termination Stats"); 3323 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3324 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3325 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3326 } 3327 3328 void G1CollectedHeap::print_termination_stats(uint worker_id, 3329 double elapsed_ms, 3330 double strong_roots_ms, 3331 double term_ms, 3332 size_t term_attempts, 3333 size_t alloc_buffer_waste, 3334 size_t undo_waste) const { 3335 log_debug(gc, task, stats) 3336 ("%3d %9.2f %9.2f %6.2f " 3337 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3338 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3339 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3340 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3341 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3342 alloc_buffer_waste * HeapWordSize / K, 3343 undo_waste * HeapWordSize / K); 3344 } 3345 3346 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3347 bool class_unloading_occurred) { 3348 uint n_workers = workers()->active_workers(); 3349 3350 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false); 3351 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred); 3352 workers()->run_task(&g1_unlink_task); 3353 } 3354 3355 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3356 bool process_strings, 3357 bool process_string_dedup) { 3358 if (!process_strings && !process_string_dedup) { 3359 // Nothing to clean. 3360 return; 3361 } 3362 3363 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false); 3364 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings); 3365 workers()->run_task(&g1_unlink_task); 3366 } 3367 3368 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3369 private: 3370 DirtyCardQueueSet* _queue; 3371 G1CollectedHeap* _g1h; 3372 public: 3373 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3374 _queue(queue), _g1h(g1h) { } 3375 3376 virtual void work(uint worker_id) { 3377 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3378 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3379 3380 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3381 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3382 3383 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3384 } 3385 }; 3386 3387 void G1CollectedHeap::redirty_logged_cards() { 3388 double redirty_logged_cards_start = os::elapsedTime(); 3389 3390 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3391 dirty_card_queue_set().reset_for_par_iteration(); 3392 workers()->run_task(&redirty_task); 3393 3394 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3395 dcq.merge_bufferlists(&dirty_card_queue_set()); 3396 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3397 3398 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3399 } 3400 3401 // Weak Reference Processing support 3402 3403 bool G1STWIsAliveClosure::do_object_b(oop p) { 3404 // An object is reachable if it is outside the collection set, 3405 // or is inside and copied. 3406 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3407 } 3408 3409 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3410 assert(obj != NULL, "must not be NULL"); 3411 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3412 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3413 // may falsely indicate that this is not the case here: however the collection set only 3414 // contains old regions when concurrent mark is not running. 3415 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3416 } 3417 3418 // Non Copying Keep Alive closure 3419 class G1KeepAliveClosure: public OopClosure { 3420 G1CollectedHeap*_g1h; 3421 public: 3422 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3423 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3424 void do_oop(oop* p) { 3425 oop obj = *p; 3426 assert(obj != NULL, "the caller should have filtered out NULL values"); 3427 3428 const InCSetState cset_state =_g1h->in_cset_state(obj); 3429 if (!cset_state.is_in_cset_or_humongous()) { 3430 return; 3431 } 3432 if (cset_state.is_in_cset()) { 3433 assert( obj->is_forwarded(), "invariant" ); 3434 *p = obj->forwardee(); 3435 } else { 3436 assert(!obj->is_forwarded(), "invariant" ); 3437 assert(cset_state.is_humongous(), 3438 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3439 _g1h->set_humongous_is_live(obj); 3440 } 3441 } 3442 }; 3443 3444 // Copying Keep Alive closure - can be called from both 3445 // serial and parallel code as long as different worker 3446 // threads utilize different G1ParScanThreadState instances 3447 // and different queues. 3448 3449 class G1CopyingKeepAliveClosure: public OopClosure { 3450 G1CollectedHeap* _g1h; 3451 G1ParScanThreadState* _par_scan_state; 3452 3453 public: 3454 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3455 G1ParScanThreadState* pss): 3456 _g1h(g1h), 3457 _par_scan_state(pss) 3458 {} 3459 3460 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3461 virtual void do_oop( oop* p) { do_oop_work(p); } 3462 3463 template <class T> void do_oop_work(T* p) { 3464 oop obj = RawAccess<>::oop_load(p); 3465 3466 if (_g1h->is_in_cset_or_humongous(obj)) { 3467 // If the referent object has been forwarded (either copied 3468 // to a new location or to itself in the event of an 3469 // evacuation failure) then we need to update the reference 3470 // field and, if both reference and referent are in the G1 3471 // heap, update the RSet for the referent. 3472 // 3473 // If the referent has not been forwarded then we have to keep 3474 // it alive by policy. Therefore we have copy the referent. 3475 // 3476 // When the queue is drained (after each phase of reference processing) 3477 // the object and it's followers will be copied, the reference field set 3478 // to point to the new location, and the RSet updated. 3479 _par_scan_state->push_on_queue(p); 3480 } 3481 } 3482 }; 3483 3484 // Serial drain queue closure. Called as the 'complete_gc' 3485 // closure for each discovered list in some of the 3486 // reference processing phases. 3487 3488 class G1STWDrainQueueClosure: public VoidClosure { 3489 protected: 3490 G1CollectedHeap* _g1h; 3491 G1ParScanThreadState* _par_scan_state; 3492 3493 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3494 3495 public: 3496 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3497 _g1h(g1h), 3498 _par_scan_state(pss) 3499 { } 3500 3501 void do_void() { 3502 G1ParScanThreadState* const pss = par_scan_state(); 3503 pss->trim_queue(); 3504 } 3505 }; 3506 3507 // Parallel Reference Processing closures 3508 3509 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3510 // processing during G1 evacuation pauses. 3511 3512 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3513 private: 3514 G1CollectedHeap* _g1h; 3515 G1ParScanThreadStateSet* _pss; 3516 RefToScanQueueSet* _queues; 3517 WorkGang* _workers; 3518 3519 public: 3520 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3521 G1ParScanThreadStateSet* per_thread_states, 3522 WorkGang* workers, 3523 RefToScanQueueSet *task_queues) : 3524 _g1h(g1h), 3525 _pss(per_thread_states), 3526 _queues(task_queues), 3527 _workers(workers) 3528 { 3529 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3530 } 3531 3532 // Executes the given task using concurrent marking worker threads. 3533 virtual void execute(ProcessTask& task, uint ergo_workers); 3534 }; 3535 3536 // Gang task for possibly parallel reference processing 3537 3538 class G1STWRefProcTaskProxy: public AbstractGangTask { 3539 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3540 ProcessTask& _proc_task; 3541 G1CollectedHeap* _g1h; 3542 G1ParScanThreadStateSet* _pss; 3543 RefToScanQueueSet* _task_queues; 3544 ParallelTaskTerminator* _terminator; 3545 3546 public: 3547 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3548 G1CollectedHeap* g1h, 3549 G1ParScanThreadStateSet* per_thread_states, 3550 RefToScanQueueSet *task_queues, 3551 ParallelTaskTerminator* terminator) : 3552 AbstractGangTask("Process reference objects in parallel"), 3553 _proc_task(proc_task), 3554 _g1h(g1h), 3555 _pss(per_thread_states), 3556 _task_queues(task_queues), 3557 _terminator(terminator) 3558 {} 3559 3560 virtual void work(uint worker_id) { 3561 // The reference processing task executed by a single worker. 3562 ResourceMark rm; 3563 HandleMark hm; 3564 3565 G1STWIsAliveClosure is_alive(_g1h); 3566 3567 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3568 pss->set_ref_discoverer(NULL); 3569 3570 // Keep alive closure. 3571 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3572 3573 // Complete GC closure 3574 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3575 3576 // Call the reference processing task's work routine. 3577 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3578 3579 // Note we cannot assert that the refs array is empty here as not all 3580 // of the processing tasks (specifically phase2 - pp2_work) execute 3581 // the complete_gc closure (which ordinarily would drain the queue) so 3582 // the queue may not be empty. 3583 } 3584 }; 3585 3586 // Driver routine for parallel reference processing. 3587 // Creates an instance of the ref processing gang 3588 // task and has the worker threads execute it. 3589 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3590 assert(_workers != NULL, "Need parallel worker threads."); 3591 3592 assert(_workers->active_workers() >= ergo_workers, 3593 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3594 ergo_workers, _workers->active_workers()); 3595 ParallelTaskTerminator terminator(ergo_workers, _queues); 3596 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3597 3598 _workers->run_task(&proc_task_proxy, ergo_workers); 3599 } 3600 3601 // End of weak reference support closures 3602 3603 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3604 double ref_proc_start = os::elapsedTime(); 3605 3606 ReferenceProcessor* rp = _ref_processor_stw; 3607 assert(rp->discovery_enabled(), "should have been enabled"); 3608 3609 // Closure to test whether a referent is alive. 3610 G1STWIsAliveClosure is_alive(this); 3611 3612 // Even when parallel reference processing is enabled, the processing 3613 // of JNI refs is serial and performed serially by the current thread 3614 // rather than by a worker. The following PSS will be used for processing 3615 // JNI refs. 3616 3617 // Use only a single queue for this PSS. 3618 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3619 pss->set_ref_discoverer(NULL); 3620 assert(pss->queue_is_empty(), "pre-condition"); 3621 3622 // Keep alive closure. 3623 G1CopyingKeepAliveClosure keep_alive(this, pss); 3624 3625 // Serial Complete GC closure 3626 G1STWDrainQueueClosure drain_queue(this, pss); 3627 3628 // Setup the soft refs policy... 3629 rp->setup_policy(false); 3630 3631 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3632 3633 ReferenceProcessorStats stats; 3634 if (!rp->processing_is_mt()) { 3635 // Serial reference processing... 3636 stats = rp->process_discovered_references(&is_alive, 3637 &keep_alive, 3638 &drain_queue, 3639 NULL, 3640 pt); 3641 } else { 3642 uint no_of_gc_workers = workers()->active_workers(); 3643 3644 // Parallel reference processing 3645 assert(no_of_gc_workers <= rp->max_num_queues(), 3646 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3647 no_of_gc_workers, rp->max_num_queues()); 3648 3649 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3650 stats = rp->process_discovered_references(&is_alive, 3651 &keep_alive, 3652 &drain_queue, 3653 &par_task_executor, 3654 pt); 3655 } 3656 3657 _gc_tracer_stw->report_gc_reference_stats(stats); 3658 3659 // We have completed copying any necessary live referent objects. 3660 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3661 3662 make_pending_list_reachable(); 3663 3664 rp->verify_no_references_recorded(); 3665 3666 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3667 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3668 } 3669 3670 void G1CollectedHeap::make_pending_list_reachable() { 3671 if (collector_state()->in_initial_mark_gc()) { 3672 oop pll_head = Universe::reference_pending_list(); 3673 if (pll_head != NULL) { 3674 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3675 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3676 } 3677 } 3678 } 3679 3680 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3681 double merge_pss_time_start = os::elapsedTime(); 3682 per_thread_states->flush(); 3683 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3684 } 3685 3686 void G1CollectedHeap::pre_evacuate_collection_set() { 3687 _expand_heap_after_alloc_failure = true; 3688 _evacuation_failed = false; 3689 3690 // Disable the hot card cache. 3691 _hot_card_cache->reset_hot_cache_claimed_index(); 3692 _hot_card_cache->set_use_cache(false); 3693 3694 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3695 _preserved_marks_set.assert_empty(); 3696 3697 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3698 3699 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3700 if (collector_state()->in_initial_mark_gc()) { 3701 double start_clear_claimed_marks = os::elapsedTime(); 3702 3703 ClassLoaderDataGraph::clear_claimed_marks(); 3704 3705 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3706 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3707 } 3708 } 3709 3710 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3711 // Should G1EvacuationFailureALot be in effect for this GC? 3712 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3713 3714 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3715 3716 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3717 3718 double start_par_time_sec = os::elapsedTime(); 3719 double end_par_time_sec; 3720 3721 { 3722 const uint n_workers = workers()->active_workers(); 3723 G1RootProcessor root_processor(this, n_workers); 3724 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3725 3726 print_termination_stats_hdr(); 3727 3728 workers()->run_task(&g1_par_task); 3729 end_par_time_sec = os::elapsedTime(); 3730 3731 // Closing the inner scope will execute the destructor 3732 // for the G1RootProcessor object. We record the current 3733 // elapsed time before closing the scope so that time 3734 // taken for the destructor is NOT included in the 3735 // reported parallel time. 3736 } 3737 3738 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3739 phase_times->record_par_time(par_time_ms); 3740 3741 double code_root_fixup_time_ms = 3742 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3743 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 3744 } 3745 3746 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3747 // Also cleans the card table from temporary duplicate detection information used 3748 // during UpdateRS/ScanRS. 3749 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 3750 3751 // Process any discovered reference objects - we have 3752 // to do this _before_ we retire the GC alloc regions 3753 // as we may have to copy some 'reachable' referent 3754 // objects (and their reachable sub-graphs) that were 3755 // not copied during the pause. 3756 process_discovered_references(per_thread_states); 3757 3758 // FIXME 3759 // CM's reference processing also cleans up the string table. 3760 // Should we do that here also? We could, but it is a serial operation 3761 // and could significantly increase the pause time. 3762 3763 G1STWIsAliveClosure is_alive(this); 3764 G1KeepAliveClosure keep_alive(this); 3765 3766 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3767 g1_policy()->phase_times()->weak_phase_times()); 3768 3769 if (G1StringDedup::is_enabled()) { 3770 double fixup_start = os::elapsedTime(); 3771 3772 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 3773 3774 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 3775 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 3776 } 3777 3778 if (evacuation_failed()) { 3779 restore_after_evac_failure(); 3780 3781 // Reset the G1EvacuationFailureALot counters and flags 3782 // Note: the values are reset only when an actual 3783 // evacuation failure occurs. 3784 NOT_PRODUCT(reset_evacuation_should_fail();) 3785 } 3786 3787 _preserved_marks_set.assert_empty(); 3788 3789 _allocator->release_gc_alloc_regions(evacuation_info); 3790 3791 merge_per_thread_state_info(per_thread_states); 3792 3793 // Reset and re-enable the hot card cache. 3794 // Note the counts for the cards in the regions in the 3795 // collection set are reset when the collection set is freed. 3796 _hot_card_cache->reset_hot_cache(); 3797 _hot_card_cache->set_use_cache(true); 3798 3799 purge_code_root_memory(); 3800 3801 redirty_logged_cards(); 3802 #if COMPILER2_OR_JVMCI 3803 double start = os::elapsedTime(); 3804 DerivedPointerTable::update_pointers(); 3805 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3806 #endif 3807 g1_policy()->print_age_table(); 3808 } 3809 3810 void G1CollectedHeap::record_obj_copy_mem_stats() { 3811 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3812 3813 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3814 create_g1_evac_summary(&_old_evac_stats)); 3815 } 3816 3817 void G1CollectedHeap::free_region(HeapRegion* hr, 3818 FreeRegionList* free_list, 3819 bool skip_remset, 3820 bool skip_hot_card_cache, 3821 bool locked) { 3822 assert(!hr->is_free(), "the region should not be free"); 3823 assert(!hr->is_empty(), "the region should not be empty"); 3824 assert(_hrm->is_available(hr->hrm_index()), "region should be committed"); 3825 assert(free_list != NULL, "pre-condition"); 3826 3827 if (G1VerifyBitmaps) { 3828 MemRegion mr(hr->bottom(), hr->end()); 3829 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3830 } 3831 3832 // Clear the card counts for this region. 3833 // Note: we only need to do this if the region is not young 3834 // (since we don't refine cards in young regions). 3835 if (!skip_hot_card_cache && !hr->is_young()) { 3836 _hot_card_cache->reset_card_counts(hr); 3837 } 3838 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3839 _g1_policy->remset_tracker()->update_at_free(hr); 3840 free_list->add_ordered(hr); 3841 } 3842 3843 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3844 FreeRegionList* free_list) { 3845 assert(hr->is_humongous(), "this is only for humongous regions"); 3846 assert(free_list != NULL, "pre-condition"); 3847 hr->clear_humongous(); 3848 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3849 } 3850 3851 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3852 const uint humongous_regions_removed) { 3853 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3854 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3855 _old_set.bulk_remove(old_regions_removed); 3856 _humongous_set.bulk_remove(humongous_regions_removed); 3857 } 3858 3859 } 3860 3861 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3862 assert(list != NULL, "list can't be null"); 3863 if (!list->is_empty()) { 3864 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3865 _hrm->insert_list_into_free_list(list); 3866 } 3867 } 3868 3869 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3870 decrease_used(bytes); 3871 } 3872 3873 class G1FreeCollectionSetTask : public AbstractGangTask { 3874 private: 3875 3876 // Closure applied to all regions in the collection set to do work that needs to 3877 // be done serially in a single thread. 3878 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3879 private: 3880 EvacuationInfo* _evacuation_info; 3881 const size_t* _surviving_young_words; 3882 3883 // Bytes used in successfully evacuated regions before the evacuation. 3884 size_t _before_used_bytes; 3885 // Bytes used in unsucessfully evacuated regions before the evacuation 3886 size_t _after_used_bytes; 3887 3888 size_t _bytes_allocated_in_old_since_last_gc; 3889 3890 size_t _failure_used_words; 3891 size_t _failure_waste_words; 3892 3893 FreeRegionList _local_free_list; 3894 public: 3895 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3896 HeapRegionClosure(), 3897 _evacuation_info(evacuation_info), 3898 _surviving_young_words(surviving_young_words), 3899 _before_used_bytes(0), 3900 _after_used_bytes(0), 3901 _bytes_allocated_in_old_since_last_gc(0), 3902 _failure_used_words(0), 3903 _failure_waste_words(0), 3904 _local_free_list("Local Region List for CSet Freeing") { 3905 } 3906 3907 virtual bool do_heap_region(HeapRegion* r) { 3908 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3909 3910 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3911 g1h->clear_in_cset(r); 3912 3913 if (r->is_young()) { 3914 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 3915 "Young index %d is wrong for region %u of type %s with %u young regions", 3916 r->young_index_in_cset(), 3917 r->hrm_index(), 3918 r->get_type_str(), 3919 g1h->collection_set()->young_region_length()); 3920 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 3921 r->record_surv_words_in_group(words_survived); 3922 } 3923 3924 if (!r->evacuation_failed()) { 3925 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 3926 _before_used_bytes += r->used(); 3927 g1h->free_region(r, 3928 &_local_free_list, 3929 true, /* skip_remset */ 3930 true, /* skip_hot_card_cache */ 3931 true /* locked */); 3932 } else { 3933 r->uninstall_surv_rate_group(); 3934 r->set_young_index_in_cset(-1); 3935 r->set_evacuation_failed(false); 3936 // When moving a young gen region to old gen, we "allocate" that whole region 3937 // there. This is in addition to any already evacuated objects. Notify the 3938 // policy about that. 3939 // Old gen regions do not cause an additional allocation: both the objects 3940 // still in the region and the ones already moved are accounted for elsewhere. 3941 if (r->is_young()) { 3942 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 3943 } 3944 // The region is now considered to be old. 3945 if(g1h->is_hetero_heap()) { 3946 if(!r->is_old()) { 3947 // The region was young before, set it as pre-matured old so that next mixed gc can move 3948 // its contents to old region which is on nv-dimm 3949 r->set_premature_old(); 3950 } 3951 } else { 3952 r->set_old(); 3953 } 3954 // Do some allocation statistics accounting. Regions that failed evacuation 3955 // are always made old, so there is no need to update anything in the young 3956 // gen statistics, but we need to update old gen statistics. 3957 size_t used_words = r->marked_bytes() / HeapWordSize; 3958 3959 _failure_used_words += used_words; 3960 _failure_waste_words += HeapRegion::GrainWords - used_words; 3961 3962 g1h->old_set_add(r); 3963 _after_used_bytes += r->used(); 3964 } 3965 return false; 3966 } 3967 3968 void complete_work() { 3969 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3970 3971 _evacuation_info->set_regions_freed(_local_free_list.length()); 3972 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 3973 3974 g1h->prepend_to_freelist(&_local_free_list); 3975 g1h->decrement_summary_bytes(_before_used_bytes); 3976 3977 G1Policy* policy = g1h->g1_policy(); 3978 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 3979 3980 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 3981 } 3982 }; 3983 3984 G1CollectionSet* _collection_set; 3985 G1SerialFreeCollectionSetClosure _cl; 3986 const size_t* _surviving_young_words; 3987 3988 size_t _rs_lengths; 3989 3990 volatile jint _serial_work_claim; 3991 3992 struct WorkItem { 3993 uint region_idx; 3994 bool is_young; 3995 bool evacuation_failed; 3996 3997 WorkItem(HeapRegion* r) { 3998 region_idx = r->hrm_index(); 3999 is_young = r->is_young(); 4000 evacuation_failed = r->evacuation_failed(); 4001 } 4002 }; 4003 4004 volatile size_t _parallel_work_claim; 4005 size_t _num_work_items; 4006 WorkItem* _work_items; 4007 4008 void do_serial_work() { 4009 // Need to grab the lock to be allowed to modify the old region list. 4010 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4011 _collection_set->iterate(&_cl); 4012 } 4013 4014 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4015 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4016 4017 HeapRegion* r = g1h->region_at(region_idx); 4018 assert(!g1h->is_on_master_free_list(r), "sanity"); 4019 4020 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4021 4022 if (!is_young) { 4023 g1h->_hot_card_cache->reset_card_counts(r); 4024 } 4025 4026 if (!evacuation_failed) { 4027 r->rem_set()->clear_locked(); 4028 } 4029 } 4030 4031 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4032 private: 4033 size_t _cur_idx; 4034 WorkItem* _work_items; 4035 public: 4036 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4037 4038 virtual bool do_heap_region(HeapRegion* r) { 4039 _work_items[_cur_idx++] = WorkItem(r); 4040 return false; 4041 } 4042 }; 4043 4044 void prepare_work() { 4045 G1PrepareFreeCollectionSetClosure cl(_work_items); 4046 _collection_set->iterate(&cl); 4047 } 4048 4049 void complete_work() { 4050 _cl.complete_work(); 4051 4052 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4053 policy->record_max_rs_lengths(_rs_lengths); 4054 policy->cset_regions_freed(); 4055 } 4056 public: 4057 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4058 AbstractGangTask("G1 Free Collection Set"), 4059 _collection_set(collection_set), 4060 _cl(evacuation_info, surviving_young_words), 4061 _surviving_young_words(surviving_young_words), 4062 _rs_lengths(0), 4063 _serial_work_claim(0), 4064 _parallel_work_claim(0), 4065 _num_work_items(collection_set->region_length()), 4066 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4067 prepare_work(); 4068 } 4069 4070 ~G1FreeCollectionSetTask() { 4071 complete_work(); 4072 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4073 } 4074 4075 // Chunk size for work distribution. The chosen value has been determined experimentally 4076 // to be a good tradeoff between overhead and achievable parallelism. 4077 static uint chunk_size() { return 32; } 4078 4079 virtual void work(uint worker_id) { 4080 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4081 4082 // Claim serial work. 4083 if (_serial_work_claim == 0) { 4084 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4085 if (value == 0) { 4086 double serial_time = os::elapsedTime(); 4087 do_serial_work(); 4088 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4089 } 4090 } 4091 4092 // Start parallel work. 4093 double young_time = 0.0; 4094 bool has_young_time = false; 4095 double non_young_time = 0.0; 4096 bool has_non_young_time = false; 4097 4098 while (true) { 4099 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4100 size_t cur = end - chunk_size(); 4101 4102 if (cur >= _num_work_items) { 4103 break; 4104 } 4105 4106 EventGCPhaseParallel event; 4107 double start_time = os::elapsedTime(); 4108 4109 end = MIN2(end, _num_work_items); 4110 4111 for (; cur < end; cur++) { 4112 bool is_young = _work_items[cur].is_young; 4113 4114 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4115 4116 double end_time = os::elapsedTime(); 4117 double time_taken = end_time - start_time; 4118 if (is_young) { 4119 young_time += time_taken; 4120 has_young_time = true; 4121 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4122 } else { 4123 non_young_time += time_taken; 4124 has_non_young_time = true; 4125 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4126 } 4127 start_time = end_time; 4128 } 4129 } 4130 4131 if (has_young_time) { 4132 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4133 } 4134 if (has_non_young_time) { 4135 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4136 } 4137 } 4138 }; 4139 4140 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4141 _eden.clear(); 4142 4143 double free_cset_start_time = os::elapsedTime(); 4144 4145 { 4146 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4147 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4148 4149 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4150 4151 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4152 cl.name(), 4153 num_workers, 4154 _collection_set.region_length()); 4155 workers()->run_task(&cl, num_workers); 4156 } 4157 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4158 4159 collection_set->clear(); 4160 } 4161 4162 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4163 private: 4164 FreeRegionList* _free_region_list; 4165 HeapRegionSet* _proxy_set; 4166 uint _humongous_objects_reclaimed; 4167 uint _humongous_regions_reclaimed; 4168 size_t _freed_bytes; 4169 public: 4170 4171 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4172 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4173 } 4174 4175 virtual bool do_heap_region(HeapRegion* r) { 4176 if (!r->is_starts_humongous()) { 4177 return false; 4178 } 4179 4180 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4181 4182 oop obj = (oop)r->bottom(); 4183 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4184 4185 // The following checks whether the humongous object is live are sufficient. 4186 // The main additional check (in addition to having a reference from the roots 4187 // or the young gen) is whether the humongous object has a remembered set entry. 4188 // 4189 // A humongous object cannot be live if there is no remembered set for it 4190 // because: 4191 // - there can be no references from within humongous starts regions referencing 4192 // the object because we never allocate other objects into them. 4193 // (I.e. there are no intra-region references that may be missed by the 4194 // remembered set) 4195 // - as soon there is a remembered set entry to the humongous starts region 4196 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4197 // until the end of a concurrent mark. 4198 // 4199 // It is not required to check whether the object has been found dead by marking 4200 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4201 // all objects allocated during that time are considered live. 4202 // SATB marking is even more conservative than the remembered set. 4203 // So if at this point in the collection there is no remembered set entry, 4204 // nobody has a reference to it. 4205 // At the start of collection we flush all refinement logs, and remembered sets 4206 // are completely up-to-date wrt to references to the humongous object. 4207 // 4208 // Other implementation considerations: 4209 // - never consider object arrays at this time because they would pose 4210 // considerable effort for cleaning up the the remembered sets. This is 4211 // required because stale remembered sets might reference locations that 4212 // are currently allocated into. 4213 uint region_idx = r->hrm_index(); 4214 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4215 !r->rem_set()->is_empty()) { 4216 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", 4217 region_idx, 4218 (size_t)obj->size() * HeapWordSize, 4219 p2i(r->bottom()), 4220 r->rem_set()->occupied(), 4221 r->rem_set()->strong_code_roots_list_length(), 4222 next_bitmap->is_marked(r->bottom()), 4223 g1h->is_humongous_reclaim_candidate(region_idx), 4224 obj->is_typeArray() 4225 ); 4226 return false; 4227 } 4228 4229 guarantee(obj->is_typeArray(), 4230 "Only eagerly reclaiming type arrays is supported, but the object " 4231 PTR_FORMAT " is not.", p2i(r->bottom())); 4232 4233 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", 4234 region_idx, 4235 (size_t)obj->size() * HeapWordSize, 4236 p2i(r->bottom()), 4237 r->rem_set()->occupied(), 4238 r->rem_set()->strong_code_roots_list_length(), 4239 next_bitmap->is_marked(r->bottom()), 4240 g1h->is_humongous_reclaim_candidate(region_idx), 4241 obj->is_typeArray() 4242 ); 4243 4244 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4245 cm->humongous_object_eagerly_reclaimed(r); 4246 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4247 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4248 region_idx, 4249 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4250 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4251 _humongous_objects_reclaimed++; 4252 do { 4253 HeapRegion* next = g1h->next_region_in_humongous(r); 4254 _freed_bytes += r->used(); 4255 r->set_containing_set(NULL); 4256 _humongous_regions_reclaimed++; 4257 g1h->free_humongous_region(r, _free_region_list); 4258 r = next; 4259 } while (r != NULL); 4260 4261 return false; 4262 } 4263 4264 uint humongous_objects_reclaimed() { 4265 return _humongous_objects_reclaimed; 4266 } 4267 4268 uint humongous_regions_reclaimed() { 4269 return _humongous_regions_reclaimed; 4270 } 4271 4272 size_t bytes_freed() const { 4273 return _freed_bytes; 4274 } 4275 }; 4276 4277 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4278 assert_at_safepoint_on_vm_thread(); 4279 4280 if (!G1EagerReclaimHumongousObjects || 4281 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4282 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4283 return; 4284 } 4285 4286 double start_time = os::elapsedTime(); 4287 4288 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4289 4290 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4291 heap_region_iterate(&cl); 4292 4293 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4294 4295 G1HRPrinter* hrp = hr_printer(); 4296 if (hrp->is_active()) { 4297 FreeRegionListIterator iter(&local_cleanup_list); 4298 while (iter.more_available()) { 4299 HeapRegion* hr = iter.get_next(); 4300 hrp->cleanup(hr); 4301 } 4302 } 4303 4304 prepend_to_freelist(&local_cleanup_list); 4305 decrement_summary_bytes(cl.bytes_freed()); 4306 4307 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4308 cl.humongous_objects_reclaimed()); 4309 } 4310 4311 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4312 public: 4313 virtual bool do_heap_region(HeapRegion* r) { 4314 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4315 G1CollectedHeap::heap()->clear_in_cset(r); 4316 r->set_young_index_in_cset(-1); 4317 return false; 4318 } 4319 }; 4320 4321 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4322 G1AbandonCollectionSetClosure cl; 4323 collection_set->iterate(&cl); 4324 4325 collection_set->clear(); 4326 collection_set->stop_incremental_building(); 4327 } 4328 4329 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4330 return _allocator->is_retained_old_region(hr); 4331 } 4332 4333 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4334 _eden.add(hr); 4335 _g1_policy->set_region_eden(hr); 4336 } 4337 4338 #ifdef ASSERT 4339 4340 class NoYoungRegionsClosure: public HeapRegionClosure { 4341 private: 4342 bool _success; 4343 public: 4344 NoYoungRegionsClosure() : _success(true) { } 4345 bool do_heap_region(HeapRegion* r) { 4346 if (r->is_young()) { 4347 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4348 p2i(r->bottom()), p2i(r->end())); 4349 _success = false; 4350 } 4351 return false; 4352 } 4353 bool success() { return _success; } 4354 }; 4355 4356 bool G1CollectedHeap::check_young_list_empty() { 4357 bool ret = (young_regions_count() == 0); 4358 4359 NoYoungRegionsClosure closure; 4360 heap_region_iterate(&closure); 4361 ret = ret && closure.success(); 4362 4363 return ret; 4364 } 4365 4366 #endif // ASSERT 4367 4368 class TearDownRegionSetsClosure : public HeapRegionClosure { 4369 HeapRegionSet *_old_set; 4370 4371 public: 4372 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4373 4374 bool do_heap_region(HeapRegion* r) { 4375 if (r->is_old()) { 4376 _old_set->remove(r); 4377 } else if(r->is_young()) { 4378 r->uninstall_surv_rate_group(); 4379 } else { 4380 // We ignore free regions, we'll empty the free list afterwards. 4381 // We ignore humongous and archive regions, we're not tearing down these 4382 // sets. 4383 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4384 "it cannot be another type"); 4385 } 4386 return false; 4387 } 4388 4389 ~TearDownRegionSetsClosure() { 4390 assert(_old_set->is_empty(), "post-condition"); 4391 } 4392 }; 4393 4394 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4395 assert_at_safepoint_on_vm_thread(); 4396 4397 if (!free_list_only) { 4398 TearDownRegionSetsClosure cl(&_old_set); 4399 heap_region_iterate(&cl); 4400 4401 // Note that emptying the _young_list is postponed and instead done as 4402 // the first step when rebuilding the regions sets again. The reason for 4403 // this is that during a full GC string deduplication needs to know if 4404 // a collected region was young or old when the full GC was initiated. 4405 } 4406 _hrm->remove_all_free_regions(); 4407 } 4408 4409 void G1CollectedHeap::increase_used(size_t bytes) { 4410 _summary_bytes_used += bytes; 4411 } 4412 4413 void G1CollectedHeap::decrease_used(size_t bytes) { 4414 assert(_summary_bytes_used >= bytes, 4415 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4416 _summary_bytes_used, bytes); 4417 _summary_bytes_used -= bytes; 4418 } 4419 4420 void G1CollectedHeap::set_used(size_t bytes) { 4421 _summary_bytes_used = bytes; 4422 } 4423 4424 class RebuildRegionSetsClosure : public HeapRegionClosure { 4425 private: 4426 bool _free_list_only; 4427 4428 HeapRegionSet* _old_set; 4429 HeapRegionManager* _hrm; 4430 4431 size_t _total_used; 4432 4433 public: 4434 RebuildRegionSetsClosure(bool free_list_only, 4435 HeapRegionSet* old_set, 4436 HeapRegionManager* hrm) : 4437 _free_list_only(free_list_only), 4438 _old_set(old_set), _hrm(hrm), _total_used(0) { 4439 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4440 if (!free_list_only) { 4441 assert(_old_set->is_empty(), "pre-condition"); 4442 } 4443 } 4444 4445 bool do_heap_region(HeapRegion* r) { 4446 if (r->is_empty()) { 4447 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets."); 4448 // Add free regions to the free list 4449 r->set_free(); 4450 _hrm->insert_into_free_list(r); 4451 } else if (!_free_list_only) { 4452 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared."); 4453 4454 if (r->is_archive() || r->is_humongous()) { 4455 // We ignore archive and humongous regions. We left these sets unchanged. 4456 } else { 4457 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4458 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4459 r->move_to_old(); 4460 _old_set->add(r); 4461 } 4462 _total_used += r->used(); 4463 } 4464 4465 return false; 4466 } 4467 4468 size_t total_used() { 4469 return _total_used; 4470 } 4471 }; 4472 4473 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4474 assert_at_safepoint_on_vm_thread(); 4475 4476 if (!free_list_only) { 4477 _eden.clear(); 4478 _survivor.clear(); 4479 } 4480 4481 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm); 4482 heap_region_iterate(&cl); 4483 4484 if (!free_list_only) { 4485 set_used(cl.total_used()); 4486 if (_archive_allocator != NULL) { 4487 _archive_allocator->clear_used(); 4488 } 4489 } 4490 assert(used() == recalculate_used(), 4491 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4492 used(), recalculate_used()); 4493 } 4494 4495 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4496 HeapRegion* hr = heap_region_containing(p); 4497 return hr->is_in(p); 4498 } 4499 4500 // Methods for the mutator alloc region 4501 4502 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4503 bool force) { 4504 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4505 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4506 if (force || should_allocate) { 4507 HeapRegion* new_alloc_region = new_region(word_size, 4508 false /* is_old */, 4509 false /* do_expand */); 4510 if (new_alloc_region != NULL) { 4511 set_region_short_lived_locked(new_alloc_region); 4512 _hr_printer.alloc(new_alloc_region, !should_allocate); 4513 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4514 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4515 return new_alloc_region; 4516 } 4517 } 4518 return NULL; 4519 } 4520 4521 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4522 size_t allocated_bytes) { 4523 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4524 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4525 4526 collection_set()->add_eden_region(alloc_region); 4527 increase_used(allocated_bytes); 4528 _hr_printer.retire(alloc_region); 4529 // We update the eden sizes here, when the region is retired, 4530 // instead of when it's allocated, since this is the point that its 4531 // used space has been recorded in _summary_bytes_used. 4532 g1mm()->update_eden_size(); 4533 } 4534 4535 // Methods for the GC alloc regions 4536 4537 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4538 if (dest.is_old()) { 4539 return true; 4540 } else { 4541 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4542 } 4543 } 4544 4545 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4546 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4547 4548 if (!has_more_regions(dest)) { 4549 return NULL; 4550 } 4551 4552 const bool is_survivor = dest.is_young(); 4553 4554 HeapRegion* new_alloc_region = new_region(word_size, 4555 !is_survivor, 4556 true /* do_expand */); 4557 if (new_alloc_region != NULL) { 4558 if (is_survivor) { 4559 new_alloc_region->set_survivor(); 4560 _survivor.add(new_alloc_region); 4561 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4562 } else { 4563 new_alloc_region->set_old(); 4564 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4565 } 4566 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4567 _hr_printer.alloc(new_alloc_region); 4568 bool during_im = collector_state()->in_initial_mark_gc(); 4569 new_alloc_region->note_start_of_copying(during_im); 4570 return new_alloc_region; 4571 } 4572 return NULL; 4573 } 4574 4575 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4576 size_t allocated_bytes, 4577 InCSetState dest) { 4578 bool during_im = collector_state()->in_initial_mark_gc(); 4579 alloc_region->note_end_of_copying(during_im); 4580 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4581 if (dest.is_old()) { 4582 old_set_add(alloc_region); 4583 } 4584 _hr_printer.retire(alloc_region); 4585 } 4586 4587 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4588 bool expanded = false; 4589 uint index = _hrm->find_highest_free(&expanded); 4590 4591 if (index != G1_NO_HRM_INDEX) { 4592 if (expanded) { 4593 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4594 HeapRegion::GrainWords * HeapWordSize); 4595 } 4596 _hrm->allocate_free_regions_starting_at(index, 1); 4597 return region_at(index); 4598 } 4599 return NULL; 4600 } 4601 4602 // Optimized nmethod scanning 4603 4604 class RegisterNMethodOopClosure: public OopClosure { 4605 G1CollectedHeap* _g1h; 4606 nmethod* _nm; 4607 4608 template <class T> void do_oop_work(T* p) { 4609 T heap_oop = RawAccess<>::oop_load(p); 4610 if (!CompressedOops::is_null(heap_oop)) { 4611 oop obj = CompressedOops::decode_not_null(heap_oop); 4612 HeapRegion* hr = _g1h->heap_region_containing(obj); 4613 assert(!hr->is_continues_humongous(), 4614 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4615 " starting at " HR_FORMAT, 4616 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4617 4618 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4619 hr->add_strong_code_root_locked(_nm); 4620 } 4621 } 4622 4623 public: 4624 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4625 _g1h(g1h), _nm(nm) {} 4626 4627 void do_oop(oop* p) { do_oop_work(p); } 4628 void do_oop(narrowOop* p) { do_oop_work(p); } 4629 }; 4630 4631 class UnregisterNMethodOopClosure: public OopClosure { 4632 G1CollectedHeap* _g1h; 4633 nmethod* _nm; 4634 4635 template <class T> void do_oop_work(T* p) { 4636 T heap_oop = RawAccess<>::oop_load(p); 4637 if (!CompressedOops::is_null(heap_oop)) { 4638 oop obj = CompressedOops::decode_not_null(heap_oop); 4639 HeapRegion* hr = _g1h->heap_region_containing(obj); 4640 assert(!hr->is_continues_humongous(), 4641 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4642 " starting at " HR_FORMAT, 4643 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4644 4645 hr->remove_strong_code_root(_nm); 4646 } 4647 } 4648 4649 public: 4650 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4651 _g1h(g1h), _nm(nm) {} 4652 4653 void do_oop(oop* p) { do_oop_work(p); } 4654 void do_oop(narrowOop* p) { do_oop_work(p); } 4655 }; 4656 4657 // Returns true if the reference points to an object that 4658 // can move in an incremental collection. 4659 bool G1CollectedHeap::is_scavengable(oop obj) { 4660 HeapRegion* hr = heap_region_containing(obj); 4661 return !hr->is_pinned(); 4662 } 4663 4664 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4665 guarantee(nm != NULL, "sanity"); 4666 RegisterNMethodOopClosure reg_cl(this, nm); 4667 nm->oops_do(®_cl); 4668 } 4669 4670 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4671 guarantee(nm != NULL, "sanity"); 4672 UnregisterNMethodOopClosure reg_cl(this, nm); 4673 nm->oops_do(®_cl, true); 4674 } 4675 4676 void G1CollectedHeap::purge_code_root_memory() { 4677 double purge_start = os::elapsedTime(); 4678 G1CodeRootSet::purge(); 4679 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4680 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4681 } 4682 4683 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4684 G1CollectedHeap* _g1h; 4685 4686 public: 4687 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4688 _g1h(g1h) {} 4689 4690 void do_code_blob(CodeBlob* cb) { 4691 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4692 if (nm == NULL) { 4693 return; 4694 } 4695 4696 if (ScavengeRootsInCode) { 4697 _g1h->register_nmethod(nm); 4698 } 4699 } 4700 }; 4701 4702 void G1CollectedHeap::rebuild_strong_code_roots() { 4703 RebuildStrongCodeRootClosure blob_cl(this); 4704 CodeCache::blobs_do(&blob_cl); 4705 } 4706 4707 void G1CollectedHeap::initialize_serviceability() { 4708 _g1mm->initialize_serviceability(); 4709 } 4710 4711 MemoryUsage G1CollectedHeap::memory_usage() { 4712 return _g1mm->memory_usage(); 4713 } 4714 4715 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4716 return _g1mm->memory_managers(); 4717 } 4718 4719 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4720 return _g1mm->memory_pools(); 4721 }