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