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/gcHeapSummary.hpp" 66 #include "gc/shared/gcId.hpp" 67 #include "gc/shared/gcLocker.hpp" 68 #include "gc/shared/gcTimer.hpp" 69 #include "gc/shared/gcTrace.hpp" 70 #include "gc/shared/gcTraceTime.inline.hpp" 71 #include "gc/shared/generationSpec.hpp" 72 #include "gc/shared/isGCActiveMark.hpp" 73 #include "gc/shared/oopStorageParState.hpp" 74 #include "gc/shared/parallelCleaning.hpp" 75 #include "gc/shared/preservedMarks.inline.hpp" 76 #include "gc/shared/suspendibleThreadSet.hpp" 77 #include "gc/shared/referenceProcessor.inline.hpp" 78 #include "gc/shared/taskqueue.inline.hpp" 79 #include "gc/shared/weakProcessor.inline.hpp" 80 #include "logging/log.hpp" 81 #include "memory/allocation.hpp" 82 #include "memory/iterator.hpp" 83 #include "memory/metaspaceShared.inline.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(MetaspaceShared::is_archive_object(obj), "must be archived object"); 831 832 // Loading an archived object makes it strongly reachable. If it is 833 // loaded during concurrent marking, it must be enqueued to the SATB 834 // queue, shading the previously white object gray. 835 G1BarrierSet::enqueue(obj); 836 837 return obj; 838 } 839 840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 841 ResourceMark rm; // For retrieving the thread names in log messages. 842 843 // The structure of this method has a lot of similarities to 844 // attempt_allocation_slow(). The reason these two were not merged 845 // into a single one is that such a method would require several "if 846 // allocation is not humongous do this, otherwise do that" 847 // conditional paths which would obscure its flow. In fact, an early 848 // version of this code did use a unified method which was harder to 849 // follow and, as a result, it had subtle bugs that were hard to 850 // track down. So keeping these two methods separate allows each to 851 // be more readable. It will be good to keep these two in sync as 852 // much as possible. 853 854 assert_heap_not_locked_and_not_at_safepoint(); 855 assert(is_humongous(word_size), "attempt_allocation_humongous() " 856 "should only be called for humongous allocations"); 857 858 // Humongous objects can exhaust the heap quickly, so we should check if we 859 // need to start a marking cycle at each humongous object allocation. We do 860 // the check before we do the actual allocation. The reason for doing it 861 // before the allocation is that we avoid having to keep track of the newly 862 // allocated memory while we do a GC. 863 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 864 word_size)) { 865 collect(GCCause::_g1_humongous_allocation); 866 } 867 868 // We will loop until a) we manage to successfully perform the 869 // allocation or b) we successfully schedule a collection which 870 // fails to perform the allocation. b) is the only case when we'll 871 // return NULL. 872 HeapWord* result = NULL; 873 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 874 bool should_try_gc; 875 uint gc_count_before; 876 877 878 { 879 MutexLockerEx x(Heap_lock); 880 881 // Given that humongous objects are not allocated in young 882 // regions, we'll first try to do the allocation without doing a 883 // collection hoping that there's enough space in the heap. 884 result = humongous_obj_allocate(word_size); 885 if (result != NULL) { 886 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 887 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 888 return result; 889 } 890 891 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 892 // the GCLocker initiated GC has been performed and then retry. This includes 893 // the case when the GC Locker is not active but has not been performed. 894 should_try_gc = !GCLocker::needs_gc(); 895 // Read the GC count while still holding the Heap_lock. 896 gc_count_before = total_collections(); 897 } 898 899 if (should_try_gc) { 900 bool succeeded; 901 result = do_collection_pause(word_size, gc_count_before, &succeeded, 902 GCCause::_g1_humongous_allocation); 903 if (result != NULL) { 904 assert(succeeded, "only way to get back a non-NULL result"); 905 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 906 Thread::current()->name(), p2i(result)); 907 return result; 908 } 909 910 if (succeeded) { 911 // We successfully scheduled a collection which failed to allocate. No 912 // point in trying to allocate further. We'll just return NULL. 913 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 914 SIZE_FORMAT " words", Thread::current()->name(), word_size); 915 return NULL; 916 } 917 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 918 Thread::current()->name(), word_size); 919 } else { 920 // Failed to schedule a collection. 921 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 922 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 923 SIZE_FORMAT " words", Thread::current()->name(), word_size); 924 return NULL; 925 } 926 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 927 // The GCLocker is either active or the GCLocker initiated 928 // GC has not yet been performed. Stall until it is and 929 // then retry the allocation. 930 GCLocker::stall_until_clear(); 931 gclocker_retry_count += 1; 932 } 933 934 935 // We can reach here if we were unsuccessful in scheduling a 936 // collection (because another thread beat us to it) or if we were 937 // stalled due to the GC locker. In either can we should retry the 938 // allocation attempt in case another thread successfully 939 // performed a collection and reclaimed enough space. 940 // Humongous object allocation always needs a lock, so we wait for the retry 941 // in the next iteration of the loop, unlike for the regular iteration case. 942 // Give a warning if we seem to be looping forever. 943 944 if ((QueuedAllocationWarningCount > 0) && 945 (try_count % QueuedAllocationWarningCount == 0)) { 946 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 947 Thread::current()->name(), try_count, word_size); 948 } 949 } 950 951 ShouldNotReachHere(); 952 return NULL; 953 } 954 955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 956 bool expect_null_mutator_alloc_region) { 957 assert_at_safepoint_on_vm_thread(); 958 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 959 "the current alloc region was unexpectedly found to be non-NULL"); 960 961 if (!is_humongous(word_size)) { 962 return _allocator->attempt_allocation_locked(word_size); 963 } else { 964 HeapWord* result = humongous_obj_allocate(word_size); 965 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 966 collector_state()->set_initiate_conc_mark_if_possible(true); 967 } 968 return result; 969 } 970 971 ShouldNotReachHere(); 972 } 973 974 class PostCompactionPrinterClosure: public HeapRegionClosure { 975 private: 976 G1HRPrinter* _hr_printer; 977 public: 978 bool do_heap_region(HeapRegion* hr) { 979 assert(!hr->is_young(), "not expecting to find young regions"); 980 _hr_printer->post_compaction(hr); 981 return false; 982 } 983 984 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 985 : _hr_printer(hr_printer) { } 986 }; 987 988 void G1CollectedHeap::print_hrm_post_compaction() { 989 if (_hr_printer.is_active()) { 990 PostCompactionPrinterClosure cl(hr_printer()); 991 heap_region_iterate(&cl); 992 } 993 } 994 995 void G1CollectedHeap::abort_concurrent_cycle() { 996 // If we start the compaction before the CM threads finish 997 // scanning the root regions we might trip them over as we'll 998 // be moving objects / updating references. So let's wait until 999 // they are done. By telling them to abort, they should complete 1000 // early. 1001 _cm->root_regions()->abort(); 1002 _cm->root_regions()->wait_until_scan_finished(); 1003 1004 // Disable discovery and empty the discovered lists 1005 // for the CM ref processor. 1006 _ref_processor_cm->disable_discovery(); 1007 _ref_processor_cm->abandon_partial_discovery(); 1008 _ref_processor_cm->verify_no_references_recorded(); 1009 1010 // Abandon current iterations of concurrent marking and concurrent 1011 // refinement, if any are in progress. 1012 concurrent_mark()->concurrent_cycle_abort(); 1013 } 1014 1015 void G1CollectedHeap::prepare_heap_for_full_collection() { 1016 // Make sure we'll choose a new allocation region afterwards. 1017 _allocator->release_mutator_alloc_region(); 1018 _allocator->abandon_gc_alloc_regions(); 1019 g1_rem_set()->cleanupHRRS(); 1020 1021 // We may have added regions to the current incremental collection 1022 // set between the last GC or pause and now. We need to clear the 1023 // incremental collection set and then start rebuilding it afresh 1024 // after this full GC. 1025 abandon_collection_set(collection_set()); 1026 1027 tear_down_region_sets(false /* free_list_only */); 1028 } 1029 1030 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1031 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1032 assert(used() == recalculate_used(), "Should be equal"); 1033 _verifier->verify_region_sets_optional(); 1034 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1035 _verifier->check_bitmaps("Full GC Start"); 1036 } 1037 1038 void G1CollectedHeap::prepare_heap_for_mutators() { 1039 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1040 ClassLoaderDataGraph::purge(); 1041 MetaspaceUtils::verify_metrics(); 1042 1043 // Prepare heap for normal collections. 1044 assert(num_free_regions() == 0, "we should not have added any free regions"); 1045 rebuild_region_sets(false /* free_list_only */); 1046 abort_refinement(); 1047 resize_if_necessary_after_full_collection(); 1048 1049 // Rebuild the strong code root lists for each region 1050 rebuild_strong_code_roots(); 1051 1052 // Start a new incremental collection set for the next pause 1053 start_new_collection_set(); 1054 1055 _allocator->init_mutator_alloc_region(); 1056 1057 // Post collection state updates. 1058 MetaspaceGC::compute_new_size(); 1059 } 1060 1061 void G1CollectedHeap::abort_refinement() { 1062 if (_hot_card_cache->use_cache()) { 1063 _hot_card_cache->reset_hot_cache(); 1064 } 1065 1066 // Discard all remembered set updates. 1067 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1068 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1069 } 1070 1071 void G1CollectedHeap::verify_after_full_collection() { 1072 _hrm.verify_optional(); 1073 _verifier->verify_region_sets_optional(); 1074 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1075 // Clear the previous marking bitmap, if needed for bitmap verification. 1076 // Note we cannot do this when we clear the next marking bitmap in 1077 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1078 // objects marked during a full GC against the previous bitmap. 1079 // But we need to clear it before calling check_bitmaps below since 1080 // the full GC has compacted objects and updated TAMS but not updated 1081 // the prev bitmap. 1082 if (G1VerifyBitmaps) { 1083 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification"); 1084 _cm->clear_prev_bitmap(workers()); 1085 } 1086 // This call implicitly verifies that the next bitmap is clear after Full GC. 1087 _verifier->check_bitmaps("Full GC End"); 1088 1089 // At this point there should be no regions in the 1090 // entire heap tagged as young. 1091 assert(check_young_list_empty(), "young list should be empty at this point"); 1092 1093 // Note: since we've just done a full GC, concurrent 1094 // marking is no longer active. Therefore we need not 1095 // re-enable reference discovery for the CM ref processor. 1096 // That will be done at the start of the next marking cycle. 1097 // We also know that the STW processor should no longer 1098 // discover any new references. 1099 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1100 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1101 _ref_processor_stw->verify_no_references_recorded(); 1102 _ref_processor_cm->verify_no_references_recorded(); 1103 } 1104 1105 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1106 // Post collection logging. 1107 // We should do this after we potentially resize the heap so 1108 // that all the COMMIT / UNCOMMIT events are generated before 1109 // the compaction events. 1110 print_hrm_post_compaction(); 1111 heap_transition->print(); 1112 print_heap_after_gc(); 1113 print_heap_regions(); 1114 #ifdef TRACESPINNING 1115 ParallelTaskTerminator::print_termination_counts(); 1116 #endif 1117 } 1118 1119 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1120 bool clear_all_soft_refs) { 1121 assert_at_safepoint_on_vm_thread(); 1122 1123 if (GCLocker::check_active_before_gc()) { 1124 // Full GC was not completed. 1125 return false; 1126 } 1127 1128 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1129 soft_ref_policy()->should_clear_all_soft_refs(); 1130 1131 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs); 1132 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1133 1134 collector.prepare_collection(); 1135 collector.collect(); 1136 collector.complete_collection(); 1137 1138 // Full collection was successfully completed. 1139 return true; 1140 } 1141 1142 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1143 // Currently, there is no facility in the do_full_collection(bool) API to notify 1144 // the caller that the collection did not succeed (e.g., because it was locked 1145 // out by the GC locker). So, right now, we'll ignore the return value. 1146 bool dummy = do_full_collection(true, /* explicit_gc */ 1147 clear_all_soft_refs); 1148 } 1149 1150 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1151 // Capacity, free and used after the GC counted as full regions to 1152 // include the waste in the following calculations. 1153 const size_t capacity_after_gc = capacity(); 1154 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1155 1156 // This is enforced in arguments.cpp. 1157 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1158 "otherwise the code below doesn't make sense"); 1159 1160 // We don't have floating point command-line arguments 1161 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1162 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1163 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1164 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1165 1166 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1167 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1168 1169 // We have to be careful here as these two calculations can overflow 1170 // 32-bit size_t's. 1171 double used_after_gc_d = (double) used_after_gc; 1172 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1173 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1174 1175 // Let's make sure that they are both under the max heap size, which 1176 // by default will make them fit into a size_t. 1177 double desired_capacity_upper_bound = (double) max_heap_size; 1178 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1179 desired_capacity_upper_bound); 1180 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1181 desired_capacity_upper_bound); 1182 1183 // We can now safely turn them into size_t's. 1184 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1185 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1186 1187 // This assert only makes sense here, before we adjust them 1188 // with respect to the min and max heap size. 1189 assert(minimum_desired_capacity <= maximum_desired_capacity, 1190 "minimum_desired_capacity = " SIZE_FORMAT ", " 1191 "maximum_desired_capacity = " SIZE_FORMAT, 1192 minimum_desired_capacity, maximum_desired_capacity); 1193 1194 // Should not be greater than the heap max size. No need to adjust 1195 // it with respect to the heap min size as it's a lower bound (i.e., 1196 // we'll try to make the capacity larger than it, not smaller). 1197 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1198 // Should not be less than the heap min size. No need to adjust it 1199 // with respect to the heap max size as it's an upper bound (i.e., 1200 // we'll try to make the capacity smaller than it, not greater). 1201 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1202 1203 if (capacity_after_gc < minimum_desired_capacity) { 1204 // Don't expand unless it's significant 1205 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1206 1207 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1208 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1209 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1210 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1211 1212 expand(expand_bytes, _workers); 1213 1214 // No expansion, now see if we want to shrink 1215 } else if (capacity_after_gc > maximum_desired_capacity) { 1216 // Capacity too large, compute shrinking size 1217 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1218 1219 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1220 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1221 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1222 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1223 1224 shrink(shrink_bytes); 1225 } 1226 } 1227 1228 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1229 bool do_gc, 1230 bool clear_all_soft_refs, 1231 bool expect_null_mutator_alloc_region, 1232 bool* gc_succeeded) { 1233 *gc_succeeded = true; 1234 // Let's attempt the allocation first. 1235 HeapWord* result = 1236 attempt_allocation_at_safepoint(word_size, 1237 expect_null_mutator_alloc_region); 1238 if (result != NULL) { 1239 return result; 1240 } 1241 1242 // In a G1 heap, we're supposed to keep allocation from failing by 1243 // incremental pauses. Therefore, at least for now, we'll favor 1244 // expansion over collection. (This might change in the future if we can 1245 // do something smarter than full collection to satisfy a failed alloc.) 1246 result = expand_and_allocate(word_size); 1247 if (result != NULL) { 1248 return result; 1249 } 1250 1251 if (do_gc) { 1252 // Expansion didn't work, we'll try to do a Full GC. 1253 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1254 clear_all_soft_refs); 1255 } 1256 1257 return NULL; 1258 } 1259 1260 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1261 bool* succeeded) { 1262 assert_at_safepoint_on_vm_thread(); 1263 1264 // Attempts to allocate followed by Full GC. 1265 HeapWord* result = 1266 satisfy_failed_allocation_helper(word_size, 1267 true, /* do_gc */ 1268 false, /* clear_all_soft_refs */ 1269 false, /* expect_null_mutator_alloc_region */ 1270 succeeded); 1271 1272 if (result != NULL || !*succeeded) { 1273 return result; 1274 } 1275 1276 // Attempts to allocate followed by Full GC that will collect all soft references. 1277 result = satisfy_failed_allocation_helper(word_size, 1278 true, /* do_gc */ 1279 true, /* clear_all_soft_refs */ 1280 true, /* expect_null_mutator_alloc_region */ 1281 succeeded); 1282 1283 if (result != NULL || !*succeeded) { 1284 return result; 1285 } 1286 1287 // Attempts to allocate, no GC 1288 result = satisfy_failed_allocation_helper(word_size, 1289 false, /* do_gc */ 1290 false, /* clear_all_soft_refs */ 1291 true, /* expect_null_mutator_alloc_region */ 1292 succeeded); 1293 1294 if (result != NULL) { 1295 return result; 1296 } 1297 1298 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1299 "Flag should have been handled and cleared prior to this point"); 1300 1301 // What else? We might try synchronous finalization later. If the total 1302 // space available is large enough for the allocation, then a more 1303 // complete compaction phase than we've tried so far might be 1304 // appropriate. 1305 return NULL; 1306 } 1307 1308 // Attempting to expand the heap sufficiently 1309 // to support an allocation of the given "word_size". If 1310 // successful, perform the allocation and return the address of the 1311 // allocated block, or else "NULL". 1312 1313 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1314 assert_at_safepoint_on_vm_thread(); 1315 1316 _verifier->verify_region_sets_optional(); 1317 1318 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1319 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1320 word_size * HeapWordSize); 1321 1322 1323 if (expand(expand_bytes, _workers)) { 1324 _hrm.verify_optional(); 1325 _verifier->verify_region_sets_optional(); 1326 return attempt_allocation_at_safepoint(word_size, 1327 false /* expect_null_mutator_alloc_region */); 1328 } 1329 return NULL; 1330 } 1331 1332 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1333 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1334 aligned_expand_bytes = align_up(aligned_expand_bytes, 1335 HeapRegion::GrainBytes); 1336 1337 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1338 expand_bytes, aligned_expand_bytes); 1339 1340 if (is_maximal_no_gc()) { 1341 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1342 return false; 1343 } 1344 1345 double expand_heap_start_time_sec = os::elapsedTime(); 1346 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1347 assert(regions_to_expand > 0, "Must expand by at least one region"); 1348 1349 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1350 if (expand_time_ms != NULL) { 1351 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1352 } 1353 1354 if (expanded_by > 0) { 1355 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1356 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1357 g1_policy()->record_new_heap_size(num_regions()); 1358 } else { 1359 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1360 1361 // The expansion of the virtual storage space was unsuccessful. 1362 // Let's see if it was because we ran out of swap. 1363 if (G1ExitOnExpansionFailure && 1364 _hrm.available() >= regions_to_expand) { 1365 // We had head room... 1366 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1367 } 1368 } 1369 return regions_to_expand > 0; 1370 } 1371 1372 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1373 size_t aligned_shrink_bytes = 1374 ReservedSpace::page_align_size_down(shrink_bytes); 1375 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1376 HeapRegion::GrainBytes); 1377 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1378 1379 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1380 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1381 1382 1383 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", 1384 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1385 if (num_regions_removed > 0) { 1386 g1_policy()->record_new_heap_size(num_regions()); 1387 } else { 1388 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1389 } 1390 } 1391 1392 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1393 _verifier->verify_region_sets_optional(); 1394 1395 // We should only reach here at the end of a Full GC which means we 1396 // should not not be holding to any GC alloc regions. The method 1397 // below will make sure of that and do any remaining clean up. 1398 _allocator->abandon_gc_alloc_regions(); 1399 1400 // Instead of tearing down / rebuilding the free lists here, we 1401 // could instead use the remove_all_pending() method on free_list to 1402 // remove only the ones that we need to remove. 1403 tear_down_region_sets(true /* free_list_only */); 1404 shrink_helper(shrink_bytes); 1405 rebuild_region_sets(true /* free_list_only */); 1406 1407 _hrm.verify_optional(); 1408 _verifier->verify_region_sets_optional(); 1409 } 1410 1411 class OldRegionSetChecker : public HeapRegionSetChecker { 1412 public: 1413 void check_mt_safety() { 1414 // Master Old Set MT safety protocol: 1415 // (a) If we're at a safepoint, operations on the master old set 1416 // should be invoked: 1417 // - by the VM thread (which will serialize them), or 1418 // - by the GC workers while holding the FreeList_lock, if we're 1419 // at a safepoint for an evacuation pause (this lock is taken 1420 // anyway when an GC alloc region is retired so that a new one 1421 // is allocated from the free list), or 1422 // - by the GC workers while holding the OldSets_lock, if we're at a 1423 // safepoint for a cleanup pause. 1424 // (b) If we're not at a safepoint, operations on the master old set 1425 // should be invoked while holding the Heap_lock. 1426 1427 if (SafepointSynchronize::is_at_safepoint()) { 1428 guarantee(Thread::current()->is_VM_thread() || 1429 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 1430 "master old set MT safety protocol at a safepoint"); 1431 } else { 1432 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 1433 } 1434 } 1435 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); } 1436 const char* get_description() { return "Old Regions"; } 1437 }; 1438 1439 class ArchiveRegionSetChecker : public HeapRegionSetChecker { 1440 public: 1441 void check_mt_safety() { 1442 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(), 1443 "May only change archive regions during initialization or safepoint."); 1444 } 1445 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); } 1446 const char* get_description() { return "Archive Regions"; } 1447 }; 1448 1449 class HumongousRegionSetChecker : public HeapRegionSetChecker { 1450 public: 1451 void check_mt_safety() { 1452 // Humongous Set MT safety protocol: 1453 // (a) If we're at a safepoint, operations on the master humongous 1454 // set should be invoked by either the VM thread (which will 1455 // serialize them) or by the GC workers while holding the 1456 // OldSets_lock. 1457 // (b) If we're not at a safepoint, operations on the master 1458 // humongous set should be invoked while holding the Heap_lock. 1459 1460 if (SafepointSynchronize::is_at_safepoint()) { 1461 guarantee(Thread::current()->is_VM_thread() || 1462 OldSets_lock->owned_by_self(), 1463 "master humongous set MT safety protocol at a safepoint"); 1464 } else { 1465 guarantee(Heap_lock->owned_by_self(), 1466 "master humongous set MT safety protocol outside a safepoint"); 1467 } 1468 } 1469 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); } 1470 const char* get_description() { return "Humongous Regions"; } 1471 }; 1472 1473 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1474 CollectedHeap(), 1475 _young_gen_sampling_thread(NULL), 1476 _workers(NULL), 1477 _collector_policy(collector_policy), 1478 _card_table(NULL), 1479 _soft_ref_policy(), 1480 _old_set("Old Region Set", new OldRegionSetChecker()), 1481 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()), 1482 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()), 1483 _bot(NULL), 1484 _listener(), 1485 _hrm(), 1486 _allocator(NULL), 1487 _verifier(NULL), 1488 _summary_bytes_used(0), 1489 _archive_allocator(NULL), 1490 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1491 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1492 _expand_heap_after_alloc_failure(true), 1493 _g1mm(NULL), 1494 _humongous_reclaim_candidates(), 1495 _has_humongous_reclaim_candidates(false), 1496 _hr_printer(), 1497 _collector_state(), 1498 _old_marking_cycles_started(0), 1499 _old_marking_cycles_completed(0), 1500 _eden(), 1501 _survivor(), 1502 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1503 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1504 _g1_policy(new G1Policy(_gc_timer_stw)), 1505 _heap_sizing_policy(NULL), 1506 _collection_set(this, _g1_policy), 1507 _hot_card_cache(NULL), 1508 _g1_rem_set(NULL), 1509 _dirty_card_queue_set(false), 1510 _cm(NULL), 1511 _cm_thread(NULL), 1512 _cr(NULL), 1513 _task_queues(NULL), 1514 _evacuation_failed(false), 1515 _evacuation_failed_info_array(NULL), 1516 _preserved_marks_set(true /* in_c_heap */), 1517 #ifndef PRODUCT 1518 _evacuation_failure_alot_for_current_gc(false), 1519 _evacuation_failure_alot_gc_number(0), 1520 _evacuation_failure_alot_count(0), 1521 #endif 1522 _ref_processor_stw(NULL), 1523 _is_alive_closure_stw(this), 1524 _is_subject_to_discovery_stw(this), 1525 _ref_processor_cm(NULL), 1526 _is_alive_closure_cm(this), 1527 _is_subject_to_discovery_cm(this), 1528 _in_cset_fast_test() { 1529 1530 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1531 true /* are_GC_task_threads */, 1532 false /* are_ConcurrentGC_threads */); 1533 _workers->initialize_workers(); 1534 _verifier = new G1HeapVerifier(this); 1535 1536 _allocator = new G1Allocator(this); 1537 1538 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1539 1540 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1541 1542 // Override the default _filler_array_max_size so that no humongous filler 1543 // objects are created. 1544 _filler_array_max_size = _humongous_object_threshold_in_words; 1545 1546 uint n_queues = ParallelGCThreads; 1547 _task_queues = new RefToScanQueueSet(n_queues); 1548 1549 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1550 1551 for (uint i = 0; i < n_queues; i++) { 1552 RefToScanQueue* q = new RefToScanQueue(); 1553 q->initialize(); 1554 _task_queues->register_queue(i, q); 1555 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1556 } 1557 1558 // Initialize the G1EvacuationFailureALot counters and flags. 1559 NOT_PRODUCT(reset_evacuation_should_fail();) 1560 1561 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1562 } 1563 1564 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1565 size_t size, 1566 size_t translation_factor) { 1567 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1568 // Allocate a new reserved space, preferring to use large pages. 1569 ReservedSpace rs(size, preferred_page_size); 1570 G1RegionToSpaceMapper* result = 1571 G1RegionToSpaceMapper::create_mapper(rs, 1572 size, 1573 rs.alignment(), 1574 HeapRegion::GrainBytes, 1575 translation_factor, 1576 mtGC); 1577 1578 os::trace_page_sizes_for_requested_size(description, 1579 size, 1580 preferred_page_size, 1581 rs.alignment(), 1582 rs.base(), 1583 rs.size()); 1584 1585 return result; 1586 } 1587 1588 jint G1CollectedHeap::initialize_concurrent_refinement() { 1589 jint ecode = JNI_OK; 1590 _cr = G1ConcurrentRefine::create(&ecode); 1591 return ecode; 1592 } 1593 1594 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1595 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1596 if (_young_gen_sampling_thread->osthread() == NULL) { 1597 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1598 return JNI_ENOMEM; 1599 } 1600 return JNI_OK; 1601 } 1602 1603 jint G1CollectedHeap::initialize() { 1604 os::enable_vtime(); 1605 1606 // Necessary to satisfy locking discipline assertions. 1607 1608 MutexLocker x(Heap_lock); 1609 1610 // While there are no constraints in the GC code that HeapWordSize 1611 // be any particular value, there are multiple other areas in the 1612 // system which believe this to be true (e.g. oop->object_size in some 1613 // cases incorrectly returns the size in wordSize units rather than 1614 // HeapWordSize). 1615 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1616 1617 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1618 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1619 size_t heap_alignment = collector_policy()->heap_alignment(); 1620 1621 // Ensure that the sizes are properly aligned. 1622 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1623 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1624 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1625 1626 // Reserve the maximum. 1627 1628 // When compressed oops are enabled, the preferred heap base 1629 // is calculated by subtracting the requested size from the 1630 // 32Gb boundary and using the result as the base address for 1631 // heap reservation. If the requested size is not aligned to 1632 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1633 // into the ReservedHeapSpace constructor) then the actual 1634 // base of the reserved heap may end up differing from the 1635 // address that was requested (i.e. the preferred heap base). 1636 // If this happens then we could end up using a non-optimal 1637 // compressed oops mode. 1638 1639 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1640 heap_alignment); 1641 1642 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1643 1644 // Create the barrier set for the entire reserved region. 1645 G1CardTable* ct = new G1CardTable(reserved_region()); 1646 ct->initialize(); 1647 G1BarrierSet* bs = new G1BarrierSet(ct); 1648 bs->initialize(); 1649 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1650 BarrierSet::set_barrier_set(bs); 1651 _card_table = ct; 1652 1653 // Create the hot card cache. 1654 _hot_card_cache = new G1HotCardCache(this); 1655 1656 // Carve out the G1 part of the heap. 1657 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1658 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1659 G1RegionToSpaceMapper* heap_storage = 1660 G1RegionToSpaceMapper::create_mapper(g1_rs, 1661 g1_rs.size(), 1662 page_size, 1663 HeapRegion::GrainBytes, 1664 1, 1665 mtJavaHeap); 1666 os::trace_page_sizes("Heap", 1667 collector_policy()->min_heap_byte_size(), 1668 max_byte_size, 1669 page_size, 1670 heap_rs.base(), 1671 heap_rs.size()); 1672 heap_storage->set_mapping_changed_listener(&_listener); 1673 1674 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1675 G1RegionToSpaceMapper* bot_storage = 1676 create_aux_memory_mapper("Block Offset Table", 1677 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1678 G1BlockOffsetTable::heap_map_factor()); 1679 1680 G1RegionToSpaceMapper* cardtable_storage = 1681 create_aux_memory_mapper("Card Table", 1682 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1683 G1CardTable::heap_map_factor()); 1684 1685 G1RegionToSpaceMapper* card_counts_storage = 1686 create_aux_memory_mapper("Card Counts Table", 1687 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1688 G1CardCounts::heap_map_factor()); 1689 1690 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1691 G1RegionToSpaceMapper* prev_bitmap_storage = 1692 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1693 G1RegionToSpaceMapper* next_bitmap_storage = 1694 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1695 1696 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1697 _card_table->initialize(cardtable_storage); 1698 // Do later initialization work for concurrent refinement. 1699 _hot_card_cache->initialize(card_counts_storage); 1700 1701 // 6843694 - ensure that the maximum region index can fit 1702 // in the remembered set structures. 1703 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1704 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1705 1706 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not 1707 // start within the first card. 1708 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card."); 1709 // Also create a G1 rem set. 1710 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1711 _g1_rem_set->initialize(max_capacity(), max_regions()); 1712 1713 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1714 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1715 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1716 "too many cards per region"); 1717 1718 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1719 1720 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1721 1722 { 1723 HeapWord* start = _hrm.reserved().start(); 1724 HeapWord* end = _hrm.reserved().end(); 1725 size_t granularity = HeapRegion::GrainBytes; 1726 1727 _in_cset_fast_test.initialize(start, end, granularity); 1728 _humongous_reclaim_candidates.initialize(start, end, granularity); 1729 } 1730 1731 // Create the G1ConcurrentMark data structure and thread. 1732 // (Must do this late, so that "max_regions" is defined.) 1733 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1734 if (_cm == NULL || !_cm->completed_initialization()) { 1735 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1736 return JNI_ENOMEM; 1737 } 1738 _cm_thread = _cm->cm_thread(); 1739 1740 // Now expand into the initial heap size. 1741 if (!expand(init_byte_size, _workers)) { 1742 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1743 return JNI_ENOMEM; 1744 } 1745 1746 // Perform any initialization actions delegated to the policy. 1747 g1_policy()->init(this, &_collection_set); 1748 1749 G1BarrierSet::satb_mark_queue_set().initialize(this, 1750 SATB_Q_CBL_mon, 1751 SATB_Q_FL_lock, 1752 G1SATBProcessCompletedThreshold, 1753 G1SATBBufferEnqueueingThresholdPercent, 1754 Shared_SATB_Q_lock); 1755 1756 jint ecode = initialize_concurrent_refinement(); 1757 if (ecode != JNI_OK) { 1758 return ecode; 1759 } 1760 1761 ecode = initialize_young_gen_sampling_thread(); 1762 if (ecode != JNI_OK) { 1763 return ecode; 1764 } 1765 1766 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1767 DirtyCardQ_FL_lock, 1768 (int)concurrent_refine()->yellow_zone(), 1769 (int)concurrent_refine()->red_zone(), 1770 Shared_DirtyCardQ_lock, 1771 NULL, // fl_owner 1772 true); // init_free_ids 1773 1774 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1775 DirtyCardQ_FL_lock, 1776 -1, // never trigger processing 1777 -1, // no limit on length 1778 Shared_DirtyCardQ_lock, 1779 &G1BarrierSet::dirty_card_queue_set()); 1780 1781 // Here we allocate the dummy HeapRegion that is required by the 1782 // G1AllocRegion class. 1783 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1784 1785 // We'll re-use the same region whether the alloc region will 1786 // require BOT updates or not and, if it doesn't, then a non-young 1787 // region will complain that it cannot support allocations without 1788 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1789 dummy_region->set_eden(); 1790 // Make sure it's full. 1791 dummy_region->set_top(dummy_region->end()); 1792 G1AllocRegion::setup(this, dummy_region); 1793 1794 _allocator->init_mutator_alloc_region(); 1795 1796 // Do create of the monitoring and management support so that 1797 // values in the heap have been properly initialized. 1798 _g1mm = new G1MonitoringSupport(this); 1799 1800 G1StringDedup::initialize(); 1801 1802 _preserved_marks_set.init(ParallelGCThreads); 1803 1804 _collection_set.initialize(max_regions()); 1805 1806 return JNI_OK; 1807 } 1808 1809 void G1CollectedHeap::stop() { 1810 // Stop all concurrent threads. We do this to make sure these threads 1811 // do not continue to execute and access resources (e.g. logging) 1812 // that are destroyed during shutdown. 1813 _cr->stop(); 1814 _young_gen_sampling_thread->stop(); 1815 _cm_thread->stop(); 1816 if (G1StringDedup::is_enabled()) { 1817 G1StringDedup::stop(); 1818 } 1819 } 1820 1821 void G1CollectedHeap::safepoint_synchronize_begin() { 1822 SuspendibleThreadSet::synchronize(); 1823 } 1824 1825 void G1CollectedHeap::safepoint_synchronize_end() { 1826 SuspendibleThreadSet::desynchronize(); 1827 } 1828 1829 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1830 return HeapRegion::max_region_size(); 1831 } 1832 1833 void G1CollectedHeap::post_initialize() { 1834 CollectedHeap::post_initialize(); 1835 ref_processing_init(); 1836 } 1837 1838 void G1CollectedHeap::ref_processing_init() { 1839 // Reference processing in G1 currently works as follows: 1840 // 1841 // * There are two reference processor instances. One is 1842 // used to record and process discovered references 1843 // during concurrent marking; the other is used to 1844 // record and process references during STW pauses 1845 // (both full and incremental). 1846 // * Both ref processors need to 'span' the entire heap as 1847 // the regions in the collection set may be dotted around. 1848 // 1849 // * For the concurrent marking ref processor: 1850 // * Reference discovery is enabled at initial marking. 1851 // * Reference discovery is disabled and the discovered 1852 // references processed etc during remarking. 1853 // * Reference discovery is MT (see below). 1854 // * Reference discovery requires a barrier (see below). 1855 // * Reference processing may or may not be MT 1856 // (depending on the value of ParallelRefProcEnabled 1857 // and ParallelGCThreads). 1858 // * A full GC disables reference discovery by the CM 1859 // ref processor and abandons any entries on it's 1860 // discovered lists. 1861 // 1862 // * For the STW processor: 1863 // * Non MT discovery is enabled at the start of a full GC. 1864 // * Processing and enqueueing during a full GC is non-MT. 1865 // * During a full GC, references are processed after marking. 1866 // 1867 // * Discovery (may or may not be MT) is enabled at the start 1868 // of an incremental evacuation pause. 1869 // * References are processed near the end of a STW evacuation pause. 1870 // * For both types of GC: 1871 // * Discovery is atomic - i.e. not concurrent. 1872 // * Reference discovery will not need a barrier. 1873 1874 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1875 1876 // Concurrent Mark ref processor 1877 _ref_processor_cm = 1878 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1879 mt_processing, // mt processing 1880 ParallelGCThreads, // degree of mt processing 1881 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1882 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1883 false, // Reference discovery is not atomic 1884 &_is_alive_closure_cm, // is alive closure 1885 true); // allow changes to number of processing threads 1886 1887 // STW ref processor 1888 _ref_processor_stw = 1889 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1890 mt_processing, // mt processing 1891 ParallelGCThreads, // degree of mt processing 1892 (ParallelGCThreads > 1), // mt discovery 1893 ParallelGCThreads, // degree of mt discovery 1894 true, // Reference discovery is atomic 1895 &_is_alive_closure_stw, // is alive closure 1896 true); // allow changes to number of processing threads 1897 } 1898 1899 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1900 return _collector_policy; 1901 } 1902 1903 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1904 return &_soft_ref_policy; 1905 } 1906 1907 size_t G1CollectedHeap::capacity() const { 1908 return _hrm.length() * HeapRegion::GrainBytes; 1909 } 1910 1911 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1912 return _hrm.total_free_bytes(); 1913 } 1914 1915 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1916 _hot_card_cache->drain(cl, worker_i); 1917 } 1918 1919 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1920 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1921 size_t n_completed_buffers = 0; 1922 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1923 n_completed_buffers++; 1924 } 1925 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1926 dcqs.clear_n_completed_buffers(); 1927 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1928 } 1929 1930 // Computes the sum of the storage used by the various regions. 1931 size_t G1CollectedHeap::used() const { 1932 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1933 if (_archive_allocator != NULL) { 1934 result += _archive_allocator->used(); 1935 } 1936 return result; 1937 } 1938 1939 size_t G1CollectedHeap::used_unlocked() const { 1940 return _summary_bytes_used; 1941 } 1942 1943 class SumUsedClosure: public HeapRegionClosure { 1944 size_t _used; 1945 public: 1946 SumUsedClosure() : _used(0) {} 1947 bool do_heap_region(HeapRegion* r) { 1948 _used += r->used(); 1949 return false; 1950 } 1951 size_t result() { return _used; } 1952 }; 1953 1954 size_t G1CollectedHeap::recalculate_used() const { 1955 SumUsedClosure blk; 1956 heap_region_iterate(&blk); 1957 return blk.result(); 1958 } 1959 1960 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1961 switch (cause) { 1962 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1963 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1964 case GCCause::_wb_conc_mark: return true; 1965 default : return false; 1966 } 1967 } 1968 1969 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1970 switch (cause) { 1971 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1972 case GCCause::_g1_humongous_allocation: return true; 1973 default: return is_user_requested_concurrent_full_gc(cause); 1974 } 1975 } 1976 1977 #ifndef PRODUCT 1978 void G1CollectedHeap::allocate_dummy_regions() { 1979 // Let's fill up most of the region 1980 size_t word_size = HeapRegion::GrainWords - 1024; 1981 // And as a result the region we'll allocate will be humongous. 1982 guarantee(is_humongous(word_size), "sanity"); 1983 1984 // _filler_array_max_size is set to humongous object threshold 1985 // but temporarily change it to use CollectedHeap::fill_with_object(). 1986 SizeTFlagSetting fs(_filler_array_max_size, word_size); 1987 1988 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1989 // Let's use the existing mechanism for the allocation 1990 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 1991 if (dummy_obj != NULL) { 1992 MemRegion mr(dummy_obj, word_size); 1993 CollectedHeap::fill_with_object(mr); 1994 } else { 1995 // If we can't allocate once, we probably cannot allocate 1996 // again. Let's get out of the loop. 1997 break; 1998 } 1999 } 2000 } 2001 #endif // !PRODUCT 2002 2003 void G1CollectedHeap::increment_old_marking_cycles_started() { 2004 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 2005 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 2006 "Wrong marking cycle count (started: %d, completed: %d)", 2007 _old_marking_cycles_started, _old_marking_cycles_completed); 2008 2009 _old_marking_cycles_started++; 2010 } 2011 2012 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 2013 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 2014 2015 // We assume that if concurrent == true, then the caller is a 2016 // concurrent thread that was joined the Suspendible Thread 2017 // Set. If there's ever a cheap way to check this, we should add an 2018 // assert here. 2019 2020 // Given that this method is called at the end of a Full GC or of a 2021 // concurrent cycle, and those can be nested (i.e., a Full GC can 2022 // interrupt a concurrent cycle), the number of full collections 2023 // completed should be either one (in the case where there was no 2024 // nesting) or two (when a Full GC interrupted a concurrent cycle) 2025 // behind the number of full collections started. 2026 2027 // This is the case for the inner caller, i.e. a Full GC. 2028 assert(concurrent || 2029 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 2030 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 2031 "for inner caller (Full GC): _old_marking_cycles_started = %u " 2032 "is inconsistent with _old_marking_cycles_completed = %u", 2033 _old_marking_cycles_started, _old_marking_cycles_completed); 2034 2035 // This is the case for the outer caller, i.e. the concurrent cycle. 2036 assert(!concurrent || 2037 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 2038 "for outer caller (concurrent cycle): " 2039 "_old_marking_cycles_started = %u " 2040 "is inconsistent with _old_marking_cycles_completed = %u", 2041 _old_marking_cycles_started, _old_marking_cycles_completed); 2042 2043 _old_marking_cycles_completed += 1; 2044 2045 // We need to clear the "in_progress" flag in the CM thread before 2046 // we wake up any waiters (especially when ExplicitInvokesConcurrent 2047 // is set) so that if a waiter requests another System.gc() it doesn't 2048 // incorrectly see that a marking cycle is still in progress. 2049 if (concurrent) { 2050 _cm_thread->set_idle(); 2051 } 2052 2053 // This notify_all() will ensure that a thread that called 2054 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 2055 // and it's waiting for a full GC to finish will be woken up. It is 2056 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 2057 FullGCCount_lock->notify_all(); 2058 } 2059 2060 void G1CollectedHeap::collect(GCCause::Cause cause) { 2061 assert_heap_not_locked(); 2062 2063 uint gc_count_before; 2064 uint old_marking_count_before; 2065 uint full_gc_count_before; 2066 bool retry_gc; 2067 2068 do { 2069 retry_gc = false; 2070 2071 { 2072 MutexLocker ml(Heap_lock); 2073 2074 // Read the GC count while holding the Heap_lock 2075 gc_count_before = total_collections(); 2076 full_gc_count_before = total_full_collections(); 2077 old_marking_count_before = _old_marking_cycles_started; 2078 } 2079 2080 if (should_do_concurrent_full_gc(cause)) { 2081 // Schedule an initial-mark evacuation pause that will start a 2082 // concurrent cycle. We're setting word_size to 0 which means that 2083 // we are not requesting a post-GC allocation. 2084 VM_G1CollectForAllocation op(0, /* word_size */ 2085 gc_count_before, 2086 cause, 2087 true, /* should_initiate_conc_mark */ 2088 g1_policy()->max_pause_time_ms()); 2089 VMThread::execute(&op); 2090 if (!op.pause_succeeded()) { 2091 if (old_marking_count_before == _old_marking_cycles_started) { 2092 retry_gc = op.should_retry_gc(); 2093 } else { 2094 // A Full GC happened while we were trying to schedule the 2095 // initial-mark GC. No point in starting a new cycle given 2096 // that the whole heap was collected anyway. 2097 } 2098 2099 if (retry_gc) { 2100 if (GCLocker::is_active_and_needs_gc()) { 2101 GCLocker::stall_until_clear(); 2102 } 2103 } 2104 } 2105 } else { 2106 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2107 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2108 2109 // Schedule a standard evacuation pause. We're setting word_size 2110 // to 0 which means that we are not requesting a post-GC allocation. 2111 VM_G1CollectForAllocation op(0, /* word_size */ 2112 gc_count_before, 2113 cause, 2114 false, /* should_initiate_conc_mark */ 2115 g1_policy()->max_pause_time_ms()); 2116 VMThread::execute(&op); 2117 } else { 2118 // Schedule a Full GC. 2119 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2120 VMThread::execute(&op); 2121 } 2122 } 2123 } while (retry_gc); 2124 } 2125 2126 bool G1CollectedHeap::is_in(const void* p) const { 2127 if (_hrm.reserved().contains(p)) { 2128 // Given that we know that p is in the reserved space, 2129 // heap_region_containing() should successfully 2130 // return the containing region. 2131 HeapRegion* hr = heap_region_containing(p); 2132 return hr->is_in(p); 2133 } else { 2134 return false; 2135 } 2136 } 2137 2138 #ifdef ASSERT 2139 bool G1CollectedHeap::is_in_exact(const void* p) const { 2140 bool contains = reserved_region().contains(p); 2141 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2142 if (contains && available) { 2143 return true; 2144 } else { 2145 return false; 2146 } 2147 } 2148 #endif 2149 2150 // Iteration functions. 2151 2152 // Iterates an ObjectClosure over all objects within a HeapRegion. 2153 2154 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2155 ObjectClosure* _cl; 2156 public: 2157 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2158 bool do_heap_region(HeapRegion* r) { 2159 if (!r->is_continues_humongous()) { 2160 r->object_iterate(_cl); 2161 } 2162 return false; 2163 } 2164 }; 2165 2166 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2167 IterateObjectClosureRegionClosure blk(cl); 2168 heap_region_iterate(&blk); 2169 } 2170 2171 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2172 _hrm.iterate(cl); 2173 } 2174 2175 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2176 HeapRegionClaimer *hrclaimer, 2177 uint worker_id) const { 2178 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2179 } 2180 2181 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2182 HeapRegionClaimer *hrclaimer) const { 2183 _hrm.par_iterate(cl, hrclaimer, 0); 2184 } 2185 2186 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2187 _collection_set.iterate(cl); 2188 } 2189 2190 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2191 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2192 } 2193 2194 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2195 HeapRegion* hr = heap_region_containing(addr); 2196 return hr->block_start(addr); 2197 } 2198 2199 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2200 HeapRegion* hr = heap_region_containing(addr); 2201 return hr->block_size(addr); 2202 } 2203 2204 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2205 HeapRegion* hr = heap_region_containing(addr); 2206 return hr->block_is_obj(addr); 2207 } 2208 2209 bool G1CollectedHeap::supports_tlab_allocation() const { 2210 return true; 2211 } 2212 2213 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2214 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2215 } 2216 2217 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2218 return _eden.length() * HeapRegion::GrainBytes; 2219 } 2220 2221 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2222 // must be equal to the humongous object limit. 2223 size_t G1CollectedHeap::max_tlab_size() const { 2224 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2225 } 2226 2227 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2228 return _allocator->unsafe_max_tlab_alloc(); 2229 } 2230 2231 size_t G1CollectedHeap::max_capacity() const { 2232 return _hrm.reserved().byte_size(); 2233 } 2234 2235 jlong G1CollectedHeap::millis_since_last_gc() { 2236 // See the notes in GenCollectedHeap::millis_since_last_gc() 2237 // for more information about the implementation. 2238 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2239 _g1_policy->collection_pause_end_millis(); 2240 if (ret_val < 0) { 2241 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2242 ". returning zero instead.", ret_val); 2243 return 0; 2244 } 2245 return ret_val; 2246 } 2247 2248 void G1CollectedHeap::deduplicate_string(oop str) { 2249 assert(java_lang_String::is_instance(str), "invariant"); 2250 2251 if (G1StringDedup::is_enabled()) { 2252 G1StringDedup::deduplicate(str); 2253 } 2254 } 2255 2256 void G1CollectedHeap::prepare_for_verify() { 2257 _verifier->prepare_for_verify(); 2258 } 2259 2260 void G1CollectedHeap::verify(VerifyOption vo) { 2261 _verifier->verify(vo); 2262 } 2263 2264 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2265 return true; 2266 } 2267 2268 const char* const* G1CollectedHeap::concurrent_phases() const { 2269 return _cm_thread->concurrent_phases(); 2270 } 2271 2272 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2273 return _cm_thread->request_concurrent_phase(phase); 2274 } 2275 2276 class PrintRegionClosure: public HeapRegionClosure { 2277 outputStream* _st; 2278 public: 2279 PrintRegionClosure(outputStream* st) : _st(st) {} 2280 bool do_heap_region(HeapRegion* r) { 2281 r->print_on(_st); 2282 return false; 2283 } 2284 }; 2285 2286 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2287 const HeapRegion* hr, 2288 const VerifyOption vo) const { 2289 switch (vo) { 2290 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2291 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2292 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2293 default: ShouldNotReachHere(); 2294 } 2295 return false; // keep some compilers happy 2296 } 2297 2298 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2299 const VerifyOption vo) const { 2300 switch (vo) { 2301 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2302 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2303 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2304 default: ShouldNotReachHere(); 2305 } 2306 return false; // keep some compilers happy 2307 } 2308 2309 void G1CollectedHeap::print_heap_regions() const { 2310 LogTarget(Trace, gc, heap, region) lt; 2311 if (lt.is_enabled()) { 2312 LogStream ls(lt); 2313 print_regions_on(&ls); 2314 } 2315 } 2316 2317 void G1CollectedHeap::print_on(outputStream* st) const { 2318 st->print(" %-20s", "garbage-first heap"); 2319 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2320 capacity()/K, used_unlocked()/K); 2321 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2322 p2i(_hrm.reserved().start()), 2323 p2i(_hrm.reserved().end())); 2324 st->cr(); 2325 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2326 uint young_regions = young_regions_count(); 2327 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2328 (size_t) young_regions * HeapRegion::GrainBytes / K); 2329 uint survivor_regions = survivor_regions_count(); 2330 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2331 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2332 st->cr(); 2333 MetaspaceUtils::print_on(st); 2334 } 2335 2336 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2337 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2338 "HS=humongous(starts), HC=humongous(continues), " 2339 "CS=collection set, F=free, A=archive, " 2340 "TAMS=top-at-mark-start (previous, next)"); 2341 PrintRegionClosure blk(st); 2342 heap_region_iterate(&blk); 2343 } 2344 2345 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2346 print_on(st); 2347 2348 // Print the per-region information. 2349 print_regions_on(st); 2350 } 2351 2352 void G1CollectedHeap::print_on_error(outputStream* st) const { 2353 this->CollectedHeap::print_on_error(st); 2354 2355 if (_cm != NULL) { 2356 st->cr(); 2357 _cm->print_on_error(st); 2358 } 2359 } 2360 2361 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2362 workers()->print_worker_threads_on(st); 2363 _cm_thread->print_on(st); 2364 st->cr(); 2365 _cm->print_worker_threads_on(st); 2366 _cr->print_threads_on(st); 2367 _young_gen_sampling_thread->print_on(st); 2368 if (G1StringDedup::is_enabled()) { 2369 G1StringDedup::print_worker_threads_on(st); 2370 } 2371 } 2372 2373 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2374 workers()->threads_do(tc); 2375 tc->do_thread(_cm_thread); 2376 _cm->threads_do(tc); 2377 _cr->threads_do(tc); 2378 tc->do_thread(_young_gen_sampling_thread); 2379 if (G1StringDedup::is_enabled()) { 2380 G1StringDedup::threads_do(tc); 2381 } 2382 } 2383 2384 void G1CollectedHeap::print_tracing_info() const { 2385 g1_rem_set()->print_summary_info(); 2386 concurrent_mark()->print_summary_info(); 2387 } 2388 2389 #ifndef PRODUCT 2390 // Helpful for debugging RSet issues. 2391 2392 class PrintRSetsClosure : public HeapRegionClosure { 2393 private: 2394 const char* _msg; 2395 size_t _occupied_sum; 2396 2397 public: 2398 bool do_heap_region(HeapRegion* r) { 2399 HeapRegionRemSet* hrrs = r->rem_set(); 2400 size_t occupied = hrrs->occupied(); 2401 _occupied_sum += occupied; 2402 2403 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2404 if (occupied == 0) { 2405 tty->print_cr(" RSet is empty"); 2406 } else { 2407 hrrs->print(); 2408 } 2409 tty->print_cr("----------"); 2410 return false; 2411 } 2412 2413 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2414 tty->cr(); 2415 tty->print_cr("========================================"); 2416 tty->print_cr("%s", msg); 2417 tty->cr(); 2418 } 2419 2420 ~PrintRSetsClosure() { 2421 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2422 tty->print_cr("========================================"); 2423 tty->cr(); 2424 } 2425 }; 2426 2427 void G1CollectedHeap::print_cset_rsets() { 2428 PrintRSetsClosure cl("Printing CSet RSets"); 2429 collection_set_iterate(&cl); 2430 } 2431 2432 void G1CollectedHeap::print_all_rsets() { 2433 PrintRSetsClosure cl("Printing All RSets");; 2434 heap_region_iterate(&cl); 2435 } 2436 #endif // PRODUCT 2437 2438 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2439 2440 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2441 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2442 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2443 2444 size_t eden_capacity_bytes = 2445 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2446 2447 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2448 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2449 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2450 } 2451 2452 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2453 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2454 stats->unused(), stats->used(), stats->region_end_waste(), 2455 stats->regions_filled(), stats->direct_allocated(), 2456 stats->failure_used(), stats->failure_waste()); 2457 } 2458 2459 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2460 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2461 gc_tracer->report_gc_heap_summary(when, heap_summary); 2462 2463 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2464 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2465 } 2466 2467 G1CollectedHeap* G1CollectedHeap::heap() { 2468 CollectedHeap* heap = Universe::heap(); 2469 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2470 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2471 return (G1CollectedHeap*)heap; 2472 } 2473 2474 void G1CollectedHeap::gc_prologue(bool full) { 2475 // always_do_update_barrier = false; 2476 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2477 2478 // This summary needs to be printed before incrementing total collections. 2479 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2480 2481 // Update common counters. 2482 increment_total_collections(full /* full gc */); 2483 if (full) { 2484 increment_old_marking_cycles_started(); 2485 } 2486 2487 // Fill TLAB's and such 2488 double start = os::elapsedTime(); 2489 ensure_parsability(true); 2490 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2491 } 2492 2493 void G1CollectedHeap::gc_epilogue(bool full) { 2494 // Update common counters. 2495 if (full) { 2496 // Update the number of full collections that have been completed. 2497 increment_old_marking_cycles_completed(false /* concurrent */); 2498 } 2499 2500 // We are at the end of the GC. Total collections has already been increased. 2501 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2502 2503 // FIXME: what is this about? 2504 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2505 // is set. 2506 #if COMPILER2_OR_JVMCI 2507 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2508 #endif 2509 // always_do_update_barrier = true; 2510 2511 double start = os::elapsedTime(); 2512 resize_all_tlabs(); 2513 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2514 2515 MemoryService::track_memory_usage(); 2516 // We have just completed a GC. Update the soft reference 2517 // policy with the new heap occupancy 2518 Universe::update_heap_info_at_gc(); 2519 } 2520 2521 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2522 uint gc_count_before, 2523 bool* succeeded, 2524 GCCause::Cause gc_cause) { 2525 assert_heap_not_locked_and_not_at_safepoint(); 2526 VM_G1CollectForAllocation op(word_size, 2527 gc_count_before, 2528 gc_cause, 2529 false, /* should_initiate_conc_mark */ 2530 g1_policy()->max_pause_time_ms()); 2531 VMThread::execute(&op); 2532 2533 HeapWord* result = op.result(); 2534 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2535 assert(result == NULL || ret_succeeded, 2536 "the result should be NULL if the VM did not succeed"); 2537 *succeeded = ret_succeeded; 2538 2539 assert_heap_not_locked(); 2540 return result; 2541 } 2542 2543 void G1CollectedHeap::do_concurrent_mark() { 2544 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2545 if (!_cm_thread->in_progress()) { 2546 _cm_thread->set_started(); 2547 CGC_lock->notify(); 2548 } 2549 } 2550 2551 size_t G1CollectedHeap::pending_card_num() { 2552 size_t extra_cards = 0; 2553 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2554 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2555 extra_cards += dcq.size(); 2556 } 2557 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2558 size_t buffer_size = dcqs.buffer_size(); 2559 size_t buffer_num = dcqs.completed_buffers_num(); 2560 2561 return buffer_size * buffer_num + extra_cards; 2562 } 2563 2564 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2565 // We don't nominate objects with many remembered set entries, on 2566 // the assumption that such objects are likely still live. 2567 HeapRegionRemSet* rem_set = r->rem_set(); 2568 2569 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2570 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2571 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2572 } 2573 2574 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2575 private: 2576 size_t _total_humongous; 2577 size_t _candidate_humongous; 2578 2579 DirtyCardQueue _dcq; 2580 2581 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2582 assert(region->is_starts_humongous(), "Must start a humongous object"); 2583 2584 oop obj = oop(region->bottom()); 2585 2586 // Dead objects cannot be eager reclaim candidates. Due to class 2587 // unloading it is unsafe to query their classes so we return early. 2588 if (g1h->is_obj_dead(obj, region)) { 2589 return false; 2590 } 2591 2592 // If we do not have a complete remembered set for the region, then we can 2593 // not be sure that we have all references to it. 2594 if (!region->rem_set()->is_complete()) { 2595 return false; 2596 } 2597 // Candidate selection must satisfy the following constraints 2598 // while concurrent marking is in progress: 2599 // 2600 // * In order to maintain SATB invariants, an object must not be 2601 // reclaimed if it was allocated before the start of marking and 2602 // has not had its references scanned. Such an object must have 2603 // its references (including type metadata) scanned to ensure no 2604 // live objects are missed by the marking process. Objects 2605 // allocated after the start of concurrent marking don't need to 2606 // be scanned. 2607 // 2608 // * An object must not be reclaimed if it is on the concurrent 2609 // mark stack. Objects allocated after the start of concurrent 2610 // marking are never pushed on the mark stack. 2611 // 2612 // Nominating only objects allocated after the start of concurrent 2613 // marking is sufficient to meet both constraints. This may miss 2614 // some objects that satisfy the constraints, but the marking data 2615 // structures don't support efficiently performing the needed 2616 // additional tests or scrubbing of the mark stack. 2617 // 2618 // However, we presently only nominate is_typeArray() objects. 2619 // A humongous object containing references induces remembered 2620 // set entries on other regions. In order to reclaim such an 2621 // object, those remembered sets would need to be cleaned up. 2622 // 2623 // We also treat is_typeArray() objects specially, allowing them 2624 // to be reclaimed even if allocated before the start of 2625 // concurrent mark. For this we rely on mark stack insertion to 2626 // exclude is_typeArray() objects, preventing reclaiming an object 2627 // that is in the mark stack. We also rely on the metadata for 2628 // such objects to be built-in and so ensured to be kept live. 2629 // Frequent allocation and drop of large binary blobs is an 2630 // important use case for eager reclaim, and this special handling 2631 // may reduce needed headroom. 2632 2633 return obj->is_typeArray() && 2634 g1h->is_potential_eager_reclaim_candidate(region); 2635 } 2636 2637 public: 2638 RegisterHumongousWithInCSetFastTestClosure() 2639 : _total_humongous(0), 2640 _candidate_humongous(0), 2641 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2642 } 2643 2644 virtual bool do_heap_region(HeapRegion* r) { 2645 if (!r->is_starts_humongous()) { 2646 return false; 2647 } 2648 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2649 2650 bool is_candidate = humongous_region_is_candidate(g1h, r); 2651 uint rindex = r->hrm_index(); 2652 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2653 if (is_candidate) { 2654 _candidate_humongous++; 2655 g1h->register_humongous_region_with_cset(rindex); 2656 // Is_candidate already filters out humongous object with large remembered sets. 2657 // If we have a humongous object with a few remembered sets, we simply flush these 2658 // remembered set entries into the DCQS. That will result in automatic 2659 // re-evaluation of their remembered set entries during the following evacuation 2660 // phase. 2661 if (!r->rem_set()->is_empty()) { 2662 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2663 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2664 G1CardTable* ct = g1h->card_table(); 2665 HeapRegionRemSetIterator hrrs(r->rem_set()); 2666 size_t card_index; 2667 while (hrrs.has_next(card_index)) { 2668 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2669 // The remembered set might contain references to already freed 2670 // regions. Filter out such entries to avoid failing card table 2671 // verification. 2672 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2673 if (*card_ptr != G1CardTable::dirty_card_val()) { 2674 *card_ptr = G1CardTable::dirty_card_val(); 2675 _dcq.enqueue(card_ptr); 2676 } 2677 } 2678 } 2679 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2680 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2681 hrrs.n_yielded(), r->rem_set()->occupied()); 2682 // We should only clear the card based remembered set here as we will not 2683 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2684 // (and probably never) we do not enter this path if there are other kind of 2685 // remembered sets for this region. 2686 r->rem_set()->clear_locked(true /* only_cardset */); 2687 // Clear_locked() above sets the state to Empty. However we want to continue 2688 // collecting remembered set entries for humongous regions that were not 2689 // reclaimed. 2690 r->rem_set()->set_state_complete(); 2691 } 2692 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2693 } 2694 _total_humongous++; 2695 2696 return false; 2697 } 2698 2699 size_t total_humongous() const { return _total_humongous; } 2700 size_t candidate_humongous() const { return _candidate_humongous; } 2701 2702 void flush_rem_set_entries() { _dcq.flush(); } 2703 }; 2704 2705 void G1CollectedHeap::register_humongous_regions_with_cset() { 2706 if (!G1EagerReclaimHumongousObjects) { 2707 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2708 return; 2709 } 2710 double time = os::elapsed_counter(); 2711 2712 // Collect reclaim candidate information and register candidates with cset. 2713 RegisterHumongousWithInCSetFastTestClosure cl; 2714 heap_region_iterate(&cl); 2715 2716 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2717 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2718 cl.total_humongous(), 2719 cl.candidate_humongous()); 2720 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2721 2722 // Finally flush all remembered set entries to re-check into the global DCQS. 2723 cl.flush_rem_set_entries(); 2724 } 2725 2726 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2727 public: 2728 bool do_heap_region(HeapRegion* hr) { 2729 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2730 hr->verify_rem_set(); 2731 } 2732 return false; 2733 } 2734 }; 2735 2736 uint G1CollectedHeap::num_task_queues() const { 2737 return _task_queues->size(); 2738 } 2739 2740 #if TASKQUEUE_STATS 2741 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2742 st->print_raw_cr("GC Task Stats"); 2743 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2744 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2745 } 2746 2747 void G1CollectedHeap::print_taskqueue_stats() const { 2748 if (!log_is_enabled(Trace, gc, task, stats)) { 2749 return; 2750 } 2751 Log(gc, task, stats) log; 2752 ResourceMark rm; 2753 LogStream ls(log.trace()); 2754 outputStream* st = &ls; 2755 2756 print_taskqueue_stats_hdr(st); 2757 2758 TaskQueueStats totals; 2759 const uint n = num_task_queues(); 2760 for (uint i = 0; i < n; ++i) { 2761 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2762 totals += task_queue(i)->stats; 2763 } 2764 st->print_raw("tot "); totals.print(st); st->cr(); 2765 2766 DEBUG_ONLY(totals.verify()); 2767 } 2768 2769 void G1CollectedHeap::reset_taskqueue_stats() { 2770 const uint n = num_task_queues(); 2771 for (uint i = 0; i < n; ++i) { 2772 task_queue(i)->stats.reset(); 2773 } 2774 } 2775 #endif // TASKQUEUE_STATS 2776 2777 void G1CollectedHeap::wait_for_root_region_scanning() { 2778 double scan_wait_start = os::elapsedTime(); 2779 // We have to wait until the CM threads finish scanning the 2780 // root regions as it's the only way to ensure that all the 2781 // objects on them have been correctly scanned before we start 2782 // moving them during the GC. 2783 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2784 double wait_time_ms = 0.0; 2785 if (waited) { 2786 double scan_wait_end = os::elapsedTime(); 2787 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2788 } 2789 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2790 } 2791 2792 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2793 private: 2794 G1HRPrinter* _hr_printer; 2795 public: 2796 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2797 2798 virtual bool do_heap_region(HeapRegion* r) { 2799 _hr_printer->cset(r); 2800 return false; 2801 } 2802 }; 2803 2804 void G1CollectedHeap::start_new_collection_set() { 2805 collection_set()->start_incremental_building(); 2806 2807 clear_cset_fast_test(); 2808 2809 guarantee(_eden.length() == 0, "eden should have been cleared"); 2810 g1_policy()->transfer_survivors_to_cset(survivor()); 2811 } 2812 2813 bool 2814 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2815 assert_at_safepoint_on_vm_thread(); 2816 guarantee(!is_gc_active(), "collection is not reentrant"); 2817 2818 if (GCLocker::check_active_before_gc()) { 2819 return false; 2820 } 2821 2822 _gc_timer_stw->register_gc_start(); 2823 2824 GCIdMark gc_id_mark; 2825 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2826 2827 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2828 ResourceMark rm; 2829 2830 g1_policy()->note_gc_start(); 2831 2832 wait_for_root_region_scanning(); 2833 2834 print_heap_before_gc(); 2835 print_heap_regions(); 2836 trace_heap_before_gc(_gc_tracer_stw); 2837 2838 _verifier->verify_region_sets_optional(); 2839 _verifier->verify_dirty_young_regions(); 2840 2841 // We should not be doing initial mark unless the conc mark thread is running 2842 if (!_cm_thread->should_terminate()) { 2843 // This call will decide whether this pause is an initial-mark 2844 // pause. If it is, in_initial_mark_gc() will return true 2845 // for the duration of this pause. 2846 g1_policy()->decide_on_conc_mark_initiation(); 2847 } 2848 2849 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2850 assert(!collector_state()->in_initial_mark_gc() || 2851 collector_state()->in_young_only_phase(), "sanity"); 2852 2853 // We also do not allow mixed GCs during marking. 2854 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2855 2856 // Record whether this pause is an initial mark. When the current 2857 // thread has completed its logging output and it's safe to signal 2858 // the CM thread, the flag's value in the policy has been reset. 2859 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2860 2861 // Inner scope for scope based logging, timers, and stats collection 2862 { 2863 EvacuationInfo evacuation_info; 2864 2865 if (collector_state()->in_initial_mark_gc()) { 2866 // We are about to start a marking cycle, so we increment the 2867 // full collection counter. 2868 increment_old_marking_cycles_started(); 2869 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2870 } 2871 2872 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2873 2874 GCTraceCPUTime tcpu; 2875 2876 G1HeapVerifier::G1VerifyType verify_type; 2877 FormatBuffer<> gc_string("Pause Young "); 2878 if (collector_state()->in_initial_mark_gc()) { 2879 gc_string.append("(Concurrent Start)"); 2880 verify_type = G1HeapVerifier::G1VerifyConcurrentStart; 2881 } else if (collector_state()->in_young_only_phase()) { 2882 if (collector_state()->in_young_gc_before_mixed()) { 2883 gc_string.append("(Prepare Mixed)"); 2884 } else { 2885 gc_string.append("(Normal)"); 2886 } 2887 verify_type = G1HeapVerifier::G1VerifyYoungNormal; 2888 } else { 2889 gc_string.append("(Mixed)"); 2890 verify_type = G1HeapVerifier::G1VerifyMixed; 2891 } 2892 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2893 2894 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2895 workers()->active_workers(), 2896 Threads::number_of_non_daemon_threads()); 2897 active_workers = workers()->update_active_workers(active_workers); 2898 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2899 2900 G1MonitoringScope ms(g1mm(), 2901 false /* full_gc */, 2902 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */); 2903 2904 G1HeapTransition heap_transition(this); 2905 size_t heap_used_bytes_before_gc = used(); 2906 2907 // Don't dynamically change the number of GC threads this early. A value of 2908 // 0 is used to indicate serial work. When parallel work is done, 2909 // it will be set. 2910 2911 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2912 IsGCActiveMark x; 2913 2914 gc_prologue(false); 2915 2916 if (VerifyRememberedSets) { 2917 log_info(gc, verify)("[Verifying RemSets before GC]"); 2918 VerifyRegionRemSetClosure v_cl; 2919 heap_region_iterate(&v_cl); 2920 } 2921 2922 _verifier->verify_before_gc(verify_type); 2923 2924 _verifier->check_bitmaps("GC Start"); 2925 2926 #if COMPILER2_OR_JVMCI 2927 DerivedPointerTable::clear(); 2928 #endif 2929 2930 // Please see comment in g1CollectedHeap.hpp and 2931 // G1CollectedHeap::ref_processing_init() to see how 2932 // reference processing currently works in G1. 2933 2934 // Enable discovery in the STW reference processor 2935 _ref_processor_stw->enable_discovery(); 2936 2937 { 2938 // We want to temporarily turn off discovery by the 2939 // CM ref processor, if necessary, and turn it back on 2940 // on again later if we do. Using a scoped 2941 // NoRefDiscovery object will do this. 2942 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 2943 2944 // Forget the current alloc region (we might even choose it to be part 2945 // of the collection set!). 2946 _allocator->release_mutator_alloc_region(); 2947 2948 // This timing is only used by the ergonomics to handle our pause target. 2949 // It is unclear why this should not include the full pause. We will 2950 // investigate this in CR 7178365. 2951 // 2952 // Preserving the old comment here if that helps the investigation: 2953 // 2954 // The elapsed time induced by the start time below deliberately elides 2955 // the possible verification above. 2956 double sample_start_time_sec = os::elapsedTime(); 2957 2958 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2959 2960 if (collector_state()->in_initial_mark_gc()) { 2961 concurrent_mark()->pre_initial_mark(); 2962 } 2963 2964 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2965 2966 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2967 2968 // Make sure the remembered sets are up to date. This needs to be 2969 // done before register_humongous_regions_with_cset(), because the 2970 // remembered sets are used there to choose eager reclaim candidates. 2971 // If the remembered sets are not up to date we might miss some 2972 // entries that need to be handled. 2973 g1_rem_set()->cleanupHRRS(); 2974 2975 register_humongous_regions_with_cset(); 2976 2977 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 2978 2979 // We call this after finalize_cset() to 2980 // ensure that the CSet has been finalized. 2981 _cm->verify_no_cset_oops(); 2982 2983 if (_hr_printer.is_active()) { 2984 G1PrintCollectionSetClosure cl(&_hr_printer); 2985 _collection_set.iterate(&cl); 2986 } 2987 2988 // Initialize the GC alloc regions. 2989 _allocator->init_gc_alloc_regions(evacuation_info); 2990 2991 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 2992 pre_evacuate_collection_set(); 2993 2994 // Actually do the work... 2995 evacuate_collection_set(&per_thread_states); 2996 2997 post_evacuate_collection_set(evacuation_info, &per_thread_states); 2998 2999 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 3000 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 3001 3002 eagerly_reclaim_humongous_regions(); 3003 3004 record_obj_copy_mem_stats(); 3005 _survivor_evac_stats.adjust_desired_plab_sz(); 3006 _old_evac_stats.adjust_desired_plab_sz(); 3007 3008 double start = os::elapsedTime(); 3009 start_new_collection_set(); 3010 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 3011 3012 if (evacuation_failed()) { 3013 double recalculate_used_start = os::elapsedTime(); 3014 set_used(recalculate_used()); 3015 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 3016 3017 if (_archive_allocator != NULL) { 3018 _archive_allocator->clear_used(); 3019 } 3020 for (uint i = 0; i < ParallelGCThreads; i++) { 3021 if (_evacuation_failed_info_array[i].has_failed()) { 3022 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 3023 } 3024 } 3025 } else { 3026 // The "used" of the the collection set have already been subtracted 3027 // when they were freed. Add in the bytes evacuated. 3028 increase_used(g1_policy()->bytes_copied_during_gc()); 3029 } 3030 3031 if (collector_state()->in_initial_mark_gc()) { 3032 // We have to do this before we notify the CM threads that 3033 // they can start working to make sure that all the 3034 // appropriate initialization is done on the CM object. 3035 concurrent_mark()->post_initial_mark(); 3036 // Note that we don't actually trigger the CM thread at 3037 // this point. We do that later when we're sure that 3038 // the current thread has completed its logging output. 3039 } 3040 3041 allocate_dummy_regions(); 3042 3043 _allocator->init_mutator_alloc_region(); 3044 3045 { 3046 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 3047 if (expand_bytes > 0) { 3048 size_t bytes_before = capacity(); 3049 // No need for an ergo logging here, 3050 // expansion_amount() does this when it returns a value > 0. 3051 double expand_ms; 3052 if (!expand(expand_bytes, _workers, &expand_ms)) { 3053 // We failed to expand the heap. Cannot do anything about it. 3054 } 3055 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 3056 } 3057 } 3058 3059 // We redo the verification but now wrt to the new CSet which 3060 // has just got initialized after the previous CSet was freed. 3061 _cm->verify_no_cset_oops(); 3062 3063 // This timing is only used by the ergonomics to handle our pause target. 3064 // It is unclear why this should not include the full pause. We will 3065 // investigate this in CR 7178365. 3066 double sample_end_time_sec = os::elapsedTime(); 3067 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 3068 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 3069 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 3070 3071 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 3072 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 3073 3074 if (VerifyRememberedSets) { 3075 log_info(gc, verify)("[Verifying RemSets after GC]"); 3076 VerifyRegionRemSetClosure v_cl; 3077 heap_region_iterate(&v_cl); 3078 } 3079 3080 _verifier->verify_after_gc(verify_type); 3081 _verifier->check_bitmaps("GC End"); 3082 3083 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 3084 _ref_processor_stw->verify_no_references_recorded(); 3085 3086 // CM reference discovery will be re-enabled if necessary. 3087 } 3088 3089 #ifdef TRACESPINNING 3090 ParallelTaskTerminator::print_termination_counts(); 3091 #endif 3092 3093 gc_epilogue(false); 3094 } 3095 3096 // Print the remainder of the GC log output. 3097 if (evacuation_failed()) { 3098 log_info(gc)("To-space exhausted"); 3099 } 3100 3101 g1_policy()->print_phases(); 3102 heap_transition.print(); 3103 3104 // It is not yet to safe to tell the concurrent mark to 3105 // start as we have some optional output below. We don't want the 3106 // output from the concurrent mark thread interfering with this 3107 // logging output either. 3108 3109 _hrm.verify_optional(); 3110 _verifier->verify_region_sets_optional(); 3111 3112 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3113 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3114 3115 print_heap_after_gc(); 3116 print_heap_regions(); 3117 trace_heap_after_gc(_gc_tracer_stw); 3118 3119 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3120 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3121 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3122 // before any GC notifications are raised. 3123 g1mm()->update_sizes(); 3124 3125 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3126 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3127 _gc_timer_stw->register_gc_end(); 3128 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3129 } 3130 // It should now be safe to tell the concurrent mark thread to start 3131 // without its logging output interfering with the logging output 3132 // that came from the pause. 3133 3134 if (should_start_conc_mark) { 3135 // CAUTION: after the doConcurrentMark() call below, 3136 // the concurrent marking thread(s) could be running 3137 // concurrently with us. Make sure that anything after 3138 // this point does not assume that we are the only GC thread 3139 // running. Note: of course, the actual marking work will 3140 // not start until the safepoint itself is released in 3141 // SuspendibleThreadSet::desynchronize(). 3142 do_concurrent_mark(); 3143 } 3144 3145 return true; 3146 } 3147 3148 void G1CollectedHeap::remove_self_forwarding_pointers() { 3149 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3150 workers()->run_task(&rsfp_task); 3151 } 3152 3153 void G1CollectedHeap::restore_after_evac_failure() { 3154 double remove_self_forwards_start = os::elapsedTime(); 3155 3156 remove_self_forwarding_pointers(); 3157 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3158 _preserved_marks_set.restore(&task_executor); 3159 3160 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3161 } 3162 3163 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3164 if (!_evacuation_failed) { 3165 _evacuation_failed = true; 3166 } 3167 3168 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3169 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3170 } 3171 3172 bool G1ParEvacuateFollowersClosure::offer_termination() { 3173 EventGCPhaseParallel event; 3174 G1ParScanThreadState* const pss = par_scan_state(); 3175 start_term_time(); 3176 const bool res = terminator()->offer_termination(); 3177 end_term_time(); 3178 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination)); 3179 return res; 3180 } 3181 3182 void G1ParEvacuateFollowersClosure::do_void() { 3183 EventGCPhaseParallel event; 3184 G1ParScanThreadState* const pss = par_scan_state(); 3185 pss->trim_queue(); 3186 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy)); 3187 do { 3188 EventGCPhaseParallel event; 3189 pss->steal_and_trim_queue(queues()); 3190 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy)); 3191 } while (!offer_termination()); 3192 } 3193 3194 class G1ParTask : public AbstractGangTask { 3195 protected: 3196 G1CollectedHeap* _g1h; 3197 G1ParScanThreadStateSet* _pss; 3198 RefToScanQueueSet* _queues; 3199 G1RootProcessor* _root_processor; 3200 ParallelTaskTerminator _terminator; 3201 uint _n_workers; 3202 3203 public: 3204 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3205 : AbstractGangTask("G1 collection"), 3206 _g1h(g1h), 3207 _pss(per_thread_states), 3208 _queues(task_queues), 3209 _root_processor(root_processor), 3210 _terminator(n_workers, _queues), 3211 _n_workers(n_workers) 3212 {} 3213 3214 void work(uint worker_id) { 3215 if (worker_id >= _n_workers) return; // no work needed this round 3216 3217 double start_sec = os::elapsedTime(); 3218 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3219 3220 { 3221 ResourceMark rm; 3222 HandleMark hm; 3223 3224 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3225 3226 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3227 pss->set_ref_discoverer(rp); 3228 3229 double start_strong_roots_sec = os::elapsedTime(); 3230 3231 _root_processor->evacuate_roots(pss, worker_id); 3232 3233 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3234 // treating the nmethods visited to act as roots for concurrent marking. 3235 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3236 // objects copied by the current evacuation. 3237 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3238 3239 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3240 3241 double term_sec = 0.0; 3242 size_t evac_term_attempts = 0; 3243 { 3244 double start = os::elapsedTime(); 3245 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3246 evac.do_void(); 3247 3248 evac_term_attempts = evac.term_attempts(); 3249 term_sec = evac.term_time(); 3250 double elapsed_sec = os::elapsedTime() - start; 3251 3252 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3253 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3254 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3255 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3256 } 3257 3258 assert(pss->queue_is_empty(), "should be empty"); 3259 3260 if (log_is_enabled(Debug, gc, task, stats)) { 3261 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3262 size_t lab_waste; 3263 size_t lab_undo_waste; 3264 pss->waste(lab_waste, lab_undo_waste); 3265 _g1h->print_termination_stats(worker_id, 3266 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3267 strong_roots_sec * 1000.0, /* strong roots time */ 3268 term_sec * 1000.0, /* evac term time */ 3269 evac_term_attempts, /* evac term attempts */ 3270 lab_waste, /* alloc buffer waste */ 3271 lab_undo_waste /* undo waste */ 3272 ); 3273 } 3274 3275 // Close the inner scope so that the ResourceMark and HandleMark 3276 // destructors are executed here and are included as part of the 3277 // "GC Worker Time". 3278 } 3279 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3280 } 3281 }; 3282 3283 void G1CollectedHeap::print_termination_stats_hdr() { 3284 log_debug(gc, task, stats)("GC Termination Stats"); 3285 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3286 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3287 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3288 } 3289 3290 void G1CollectedHeap::print_termination_stats(uint worker_id, 3291 double elapsed_ms, 3292 double strong_roots_ms, 3293 double term_ms, 3294 size_t term_attempts, 3295 size_t alloc_buffer_waste, 3296 size_t undo_waste) const { 3297 log_debug(gc, task, stats) 3298 ("%3d %9.2f %9.2f %6.2f " 3299 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3300 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3301 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3302 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3303 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3304 alloc_buffer_waste * HeapWordSize / K, 3305 undo_waste * HeapWordSize / K); 3306 } 3307 3308 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3309 bool class_unloading_occurred) { 3310 uint n_workers = workers()->active_workers(); 3311 3312 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false); 3313 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred); 3314 workers()->run_task(&g1_unlink_task); 3315 } 3316 3317 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3318 bool process_strings, 3319 bool process_string_dedup) { 3320 if (!process_strings && !process_string_dedup) { 3321 // Nothing to clean. 3322 return; 3323 } 3324 3325 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false); 3326 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings); 3327 workers()->run_task(&g1_unlink_task); 3328 } 3329 3330 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3331 private: 3332 DirtyCardQueueSet* _queue; 3333 G1CollectedHeap* _g1h; 3334 public: 3335 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3336 _queue(queue), _g1h(g1h) { } 3337 3338 virtual void work(uint worker_id) { 3339 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3340 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3341 3342 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3343 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3344 3345 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3346 } 3347 }; 3348 3349 void G1CollectedHeap::redirty_logged_cards() { 3350 double redirty_logged_cards_start = os::elapsedTime(); 3351 3352 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3353 dirty_card_queue_set().reset_for_par_iteration(); 3354 workers()->run_task(&redirty_task); 3355 3356 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3357 dcq.merge_bufferlists(&dirty_card_queue_set()); 3358 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3359 3360 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3361 } 3362 3363 // Weak Reference Processing support 3364 3365 bool G1STWIsAliveClosure::do_object_b(oop p) { 3366 // An object is reachable if it is outside the collection set, 3367 // or is inside and copied. 3368 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3369 } 3370 3371 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3372 assert(obj != NULL, "must not be NULL"); 3373 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3374 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3375 // may falsely indicate that this is not the case here: however the collection set only 3376 // contains old regions when concurrent mark is not running. 3377 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3378 } 3379 3380 // Non Copying Keep Alive closure 3381 class G1KeepAliveClosure: public OopClosure { 3382 G1CollectedHeap*_g1h; 3383 public: 3384 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3385 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3386 void do_oop(oop* p) { 3387 oop obj = *p; 3388 assert(obj != NULL, "the caller should have filtered out NULL values"); 3389 3390 const InCSetState cset_state =_g1h->in_cset_state(obj); 3391 if (!cset_state.is_in_cset_or_humongous()) { 3392 return; 3393 } 3394 if (cset_state.is_in_cset()) { 3395 assert( obj->is_forwarded(), "invariant" ); 3396 *p = obj->forwardee(); 3397 } else { 3398 assert(!obj->is_forwarded(), "invariant" ); 3399 assert(cset_state.is_humongous(), 3400 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3401 _g1h->set_humongous_is_live(obj); 3402 } 3403 } 3404 }; 3405 3406 // Copying Keep Alive closure - can be called from both 3407 // serial and parallel code as long as different worker 3408 // threads utilize different G1ParScanThreadState instances 3409 // and different queues. 3410 3411 class G1CopyingKeepAliveClosure: public OopClosure { 3412 G1CollectedHeap* _g1h; 3413 G1ParScanThreadState* _par_scan_state; 3414 3415 public: 3416 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3417 G1ParScanThreadState* pss): 3418 _g1h(g1h), 3419 _par_scan_state(pss) 3420 {} 3421 3422 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3423 virtual void do_oop( oop* p) { do_oop_work(p); } 3424 3425 template <class T> void do_oop_work(T* p) { 3426 oop obj = RawAccess<>::oop_load(p); 3427 3428 if (_g1h->is_in_cset_or_humongous(obj)) { 3429 // If the referent object has been forwarded (either copied 3430 // to a new location or to itself in the event of an 3431 // evacuation failure) then we need to update the reference 3432 // field and, if both reference and referent are in the G1 3433 // heap, update the RSet for the referent. 3434 // 3435 // If the referent has not been forwarded then we have to keep 3436 // it alive by policy. Therefore we have copy the referent. 3437 // 3438 // When the queue is drained (after each phase of reference processing) 3439 // the object and it's followers will be copied, the reference field set 3440 // to point to the new location, and the RSet updated. 3441 _par_scan_state->push_on_queue(p); 3442 } 3443 } 3444 }; 3445 3446 // Serial drain queue closure. Called as the 'complete_gc' 3447 // closure for each discovered list in some of the 3448 // reference processing phases. 3449 3450 class G1STWDrainQueueClosure: public VoidClosure { 3451 protected: 3452 G1CollectedHeap* _g1h; 3453 G1ParScanThreadState* _par_scan_state; 3454 3455 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3456 3457 public: 3458 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3459 _g1h(g1h), 3460 _par_scan_state(pss) 3461 { } 3462 3463 void do_void() { 3464 G1ParScanThreadState* const pss = par_scan_state(); 3465 pss->trim_queue(); 3466 } 3467 }; 3468 3469 // Parallel Reference Processing closures 3470 3471 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3472 // processing during G1 evacuation pauses. 3473 3474 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3475 private: 3476 G1CollectedHeap* _g1h; 3477 G1ParScanThreadStateSet* _pss; 3478 RefToScanQueueSet* _queues; 3479 WorkGang* _workers; 3480 3481 public: 3482 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3483 G1ParScanThreadStateSet* per_thread_states, 3484 WorkGang* workers, 3485 RefToScanQueueSet *task_queues) : 3486 _g1h(g1h), 3487 _pss(per_thread_states), 3488 _queues(task_queues), 3489 _workers(workers) 3490 { 3491 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers()); 3492 } 3493 3494 // Executes the given task using concurrent marking worker threads. 3495 virtual void execute(ProcessTask& task, uint ergo_workers); 3496 }; 3497 3498 // Gang task for possibly parallel reference processing 3499 3500 class G1STWRefProcTaskProxy: public AbstractGangTask { 3501 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3502 ProcessTask& _proc_task; 3503 G1CollectedHeap* _g1h; 3504 G1ParScanThreadStateSet* _pss; 3505 RefToScanQueueSet* _task_queues; 3506 ParallelTaskTerminator* _terminator; 3507 3508 public: 3509 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3510 G1CollectedHeap* g1h, 3511 G1ParScanThreadStateSet* per_thread_states, 3512 RefToScanQueueSet *task_queues, 3513 ParallelTaskTerminator* terminator) : 3514 AbstractGangTask("Process reference objects in parallel"), 3515 _proc_task(proc_task), 3516 _g1h(g1h), 3517 _pss(per_thread_states), 3518 _task_queues(task_queues), 3519 _terminator(terminator) 3520 {} 3521 3522 virtual void work(uint worker_id) { 3523 // The reference processing task executed by a single worker. 3524 ResourceMark rm; 3525 HandleMark hm; 3526 3527 G1STWIsAliveClosure is_alive(_g1h); 3528 3529 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3530 pss->set_ref_discoverer(NULL); 3531 3532 // Keep alive closure. 3533 G1CopyingKeepAliveClosure keep_alive(_g1h, pss); 3534 3535 // Complete GC closure 3536 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3537 3538 // Call the reference processing task's work routine. 3539 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3540 3541 // Note we cannot assert that the refs array is empty here as not all 3542 // of the processing tasks (specifically phase2 - pp2_work) execute 3543 // the complete_gc closure (which ordinarily would drain the queue) so 3544 // the queue may not be empty. 3545 } 3546 }; 3547 3548 // Driver routine for parallel reference processing. 3549 // Creates an instance of the ref processing gang 3550 // task and has the worker threads execute it. 3551 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) { 3552 assert(_workers != NULL, "Need parallel worker threads."); 3553 3554 assert(_workers->active_workers() >= ergo_workers, 3555 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)", 3556 ergo_workers, _workers->active_workers()); 3557 ParallelTaskTerminator terminator(ergo_workers, _queues); 3558 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3559 3560 _workers->run_task(&proc_task_proxy, ergo_workers); 3561 } 3562 3563 // End of weak reference support closures 3564 3565 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3566 double ref_proc_start = os::elapsedTime(); 3567 3568 ReferenceProcessor* rp = _ref_processor_stw; 3569 assert(rp->discovery_enabled(), "should have been enabled"); 3570 3571 // Closure to test whether a referent is alive. 3572 G1STWIsAliveClosure is_alive(this); 3573 3574 // Even when parallel reference processing is enabled, the processing 3575 // of JNI refs is serial and performed serially by the current thread 3576 // rather than by a worker. The following PSS will be used for processing 3577 // JNI refs. 3578 3579 // Use only a single queue for this PSS. 3580 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3581 pss->set_ref_discoverer(NULL); 3582 assert(pss->queue_is_empty(), "pre-condition"); 3583 3584 // Keep alive closure. 3585 G1CopyingKeepAliveClosure keep_alive(this, pss); 3586 3587 // Serial Complete GC closure 3588 G1STWDrainQueueClosure drain_queue(this, pss); 3589 3590 // Setup the soft refs policy... 3591 rp->setup_policy(false); 3592 3593 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3594 3595 ReferenceProcessorStats stats; 3596 if (!rp->processing_is_mt()) { 3597 // Serial reference processing... 3598 stats = rp->process_discovered_references(&is_alive, 3599 &keep_alive, 3600 &drain_queue, 3601 NULL, 3602 pt); 3603 } else { 3604 uint no_of_gc_workers = workers()->active_workers(); 3605 3606 // Parallel reference processing 3607 assert(no_of_gc_workers <= rp->max_num_queues(), 3608 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3609 no_of_gc_workers, rp->max_num_queues()); 3610 3611 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues); 3612 stats = rp->process_discovered_references(&is_alive, 3613 &keep_alive, 3614 &drain_queue, 3615 &par_task_executor, 3616 pt); 3617 } 3618 3619 _gc_tracer_stw->report_gc_reference_stats(stats); 3620 3621 // We have completed copying any necessary live referent objects. 3622 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3623 3624 make_pending_list_reachable(); 3625 3626 rp->verify_no_references_recorded(); 3627 3628 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3629 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3630 } 3631 3632 void G1CollectedHeap::make_pending_list_reachable() { 3633 if (collector_state()->in_initial_mark_gc()) { 3634 oop pll_head = Universe::reference_pending_list(); 3635 if (pll_head != NULL) { 3636 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3637 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3638 } 3639 } 3640 } 3641 3642 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3643 double merge_pss_time_start = os::elapsedTime(); 3644 per_thread_states->flush(); 3645 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3646 } 3647 3648 void G1CollectedHeap::pre_evacuate_collection_set() { 3649 _expand_heap_after_alloc_failure = true; 3650 _evacuation_failed = false; 3651 3652 // Disable the hot card cache. 3653 _hot_card_cache->reset_hot_cache_claimed_index(); 3654 _hot_card_cache->set_use_cache(false); 3655 3656 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3657 _preserved_marks_set.assert_empty(); 3658 3659 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3660 3661 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3662 if (collector_state()->in_initial_mark_gc()) { 3663 double start_clear_claimed_marks = os::elapsedTime(); 3664 3665 ClassLoaderDataGraph::clear_claimed_marks(); 3666 3667 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 3668 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 3669 } 3670 } 3671 3672 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 3673 // Should G1EvacuationFailureALot be in effect for this GC? 3674 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 3675 3676 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 3677 3678 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3679 3680 double start_par_time_sec = os::elapsedTime(); 3681 double end_par_time_sec; 3682 3683 { 3684 const uint n_workers = workers()->active_workers(); 3685 G1RootProcessor root_processor(this, n_workers); 3686 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 3687 3688 print_termination_stats_hdr(); 3689 3690 workers()->run_task(&g1_par_task); 3691 end_par_time_sec = os::elapsedTime(); 3692 3693 // Closing the inner scope will execute the destructor 3694 // for the G1RootProcessor object. We record the current 3695 // elapsed time before closing the scope so that time 3696 // taken for the destructor is NOT included in the 3697 // reported parallel time. 3698 } 3699 3700 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 3701 phase_times->record_par_time(par_time_ms); 3702 3703 double code_root_fixup_time_ms = 3704 (os::elapsedTime() - end_par_time_sec) * 1000.0; 3705 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 3706 } 3707 3708 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 3709 // Also cleans the card table from temporary duplicate detection information used 3710 // during UpdateRS/ScanRS. 3711 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 3712 3713 // Process any discovered reference objects - we have 3714 // to do this _before_ we retire the GC alloc regions 3715 // as we may have to copy some 'reachable' referent 3716 // objects (and their reachable sub-graphs) that were 3717 // not copied during the pause. 3718 process_discovered_references(per_thread_states); 3719 3720 // FIXME 3721 // CM's reference processing also cleans up the string table. 3722 // Should we do that here also? We could, but it is a serial operation 3723 // and could significantly increase the pause time. 3724 3725 G1STWIsAliveClosure is_alive(this); 3726 G1KeepAliveClosure keep_alive(this); 3727 3728 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, 3729 g1_policy()->phase_times()->weak_phase_times()); 3730 3731 if (G1StringDedup::is_enabled()) { 3732 double fixup_start = os::elapsedTime(); 3733 3734 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 3735 3736 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 3737 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 3738 } 3739 3740 if (evacuation_failed()) { 3741 restore_after_evac_failure(); 3742 3743 // Reset the G1EvacuationFailureALot counters and flags 3744 // Note: the values are reset only when an actual 3745 // evacuation failure occurs. 3746 NOT_PRODUCT(reset_evacuation_should_fail();) 3747 } 3748 3749 _preserved_marks_set.assert_empty(); 3750 3751 _allocator->release_gc_alloc_regions(evacuation_info); 3752 3753 merge_per_thread_state_info(per_thread_states); 3754 3755 // Reset and re-enable the hot card cache. 3756 // Note the counts for the cards in the regions in the 3757 // collection set are reset when the collection set is freed. 3758 _hot_card_cache->reset_hot_cache(); 3759 _hot_card_cache->set_use_cache(true); 3760 3761 purge_code_root_memory(); 3762 3763 redirty_logged_cards(); 3764 #if COMPILER2_OR_JVMCI 3765 double start = os::elapsedTime(); 3766 DerivedPointerTable::update_pointers(); 3767 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 3768 #endif 3769 g1_policy()->print_age_table(); 3770 } 3771 3772 void G1CollectedHeap::record_obj_copy_mem_stats() { 3773 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 3774 3775 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 3776 create_g1_evac_summary(&_old_evac_stats)); 3777 } 3778 3779 void G1CollectedHeap::free_region(HeapRegion* hr, 3780 FreeRegionList* free_list, 3781 bool skip_remset, 3782 bool skip_hot_card_cache, 3783 bool locked) { 3784 assert(!hr->is_free(), "the region should not be free"); 3785 assert(!hr->is_empty(), "the region should not be empty"); 3786 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 3787 assert(free_list != NULL, "pre-condition"); 3788 3789 if (G1VerifyBitmaps) { 3790 MemRegion mr(hr->bottom(), hr->end()); 3791 concurrent_mark()->clear_range_in_prev_bitmap(mr); 3792 } 3793 3794 // Clear the card counts for this region. 3795 // Note: we only need to do this if the region is not young 3796 // (since we don't refine cards in young regions). 3797 if (!skip_hot_card_cache && !hr->is_young()) { 3798 _hot_card_cache->reset_card_counts(hr); 3799 } 3800 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 3801 _g1_policy->remset_tracker()->update_at_free(hr); 3802 free_list->add_ordered(hr); 3803 } 3804 3805 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 3806 FreeRegionList* free_list) { 3807 assert(hr->is_humongous(), "this is only for humongous regions"); 3808 assert(free_list != NULL, "pre-condition"); 3809 hr->clear_humongous(); 3810 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 3811 } 3812 3813 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 3814 const uint humongous_regions_removed) { 3815 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 3816 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3817 _old_set.bulk_remove(old_regions_removed); 3818 _humongous_set.bulk_remove(humongous_regions_removed); 3819 } 3820 3821 } 3822 3823 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 3824 assert(list != NULL, "list can't be null"); 3825 if (!list->is_empty()) { 3826 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 3827 _hrm.insert_list_into_free_list(list); 3828 } 3829 } 3830 3831 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 3832 decrease_used(bytes); 3833 } 3834 3835 class G1FreeCollectionSetTask : public AbstractGangTask { 3836 private: 3837 3838 // Closure applied to all regions in the collection set to do work that needs to 3839 // be done serially in a single thread. 3840 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 3841 private: 3842 EvacuationInfo* _evacuation_info; 3843 const size_t* _surviving_young_words; 3844 3845 // Bytes used in successfully evacuated regions before the evacuation. 3846 size_t _before_used_bytes; 3847 // Bytes used in unsucessfully evacuated regions before the evacuation 3848 size_t _after_used_bytes; 3849 3850 size_t _bytes_allocated_in_old_since_last_gc; 3851 3852 size_t _failure_used_words; 3853 size_t _failure_waste_words; 3854 3855 FreeRegionList _local_free_list; 3856 public: 3857 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 3858 HeapRegionClosure(), 3859 _evacuation_info(evacuation_info), 3860 _surviving_young_words(surviving_young_words), 3861 _before_used_bytes(0), 3862 _after_used_bytes(0), 3863 _bytes_allocated_in_old_since_last_gc(0), 3864 _failure_used_words(0), 3865 _failure_waste_words(0), 3866 _local_free_list("Local Region List for CSet Freeing") { 3867 } 3868 3869 virtual bool do_heap_region(HeapRegion* r) { 3870 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3871 3872 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 3873 g1h->clear_in_cset(r); 3874 3875 if (r->is_young()) { 3876 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 3877 "Young index %d is wrong for region %u of type %s with %u young regions", 3878 r->young_index_in_cset(), 3879 r->hrm_index(), 3880 r->get_type_str(), 3881 g1h->collection_set()->young_region_length()); 3882 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 3883 r->record_surv_words_in_group(words_survived); 3884 } 3885 3886 if (!r->evacuation_failed()) { 3887 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 3888 _before_used_bytes += r->used(); 3889 g1h->free_region(r, 3890 &_local_free_list, 3891 true, /* skip_remset */ 3892 true, /* skip_hot_card_cache */ 3893 true /* locked */); 3894 } else { 3895 r->uninstall_surv_rate_group(); 3896 r->set_young_index_in_cset(-1); 3897 r->set_evacuation_failed(false); 3898 // When moving a young gen region to old gen, we "allocate" that whole region 3899 // there. This is in addition to any already evacuated objects. Notify the 3900 // policy about that. 3901 // Old gen regions do not cause an additional allocation: both the objects 3902 // still in the region and the ones already moved are accounted for elsewhere. 3903 if (r->is_young()) { 3904 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 3905 } 3906 // The region is now considered to be old. 3907 r->set_old(); 3908 // Do some allocation statistics accounting. Regions that failed evacuation 3909 // are always made old, so there is no need to update anything in the young 3910 // gen statistics, but we need to update old gen statistics. 3911 size_t used_words = r->marked_bytes() / HeapWordSize; 3912 3913 _failure_used_words += used_words; 3914 _failure_waste_words += HeapRegion::GrainWords - used_words; 3915 3916 g1h->old_set_add(r); 3917 _after_used_bytes += r->used(); 3918 } 3919 return false; 3920 } 3921 3922 void complete_work() { 3923 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3924 3925 _evacuation_info->set_regions_freed(_local_free_list.length()); 3926 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 3927 3928 g1h->prepend_to_freelist(&_local_free_list); 3929 g1h->decrement_summary_bytes(_before_used_bytes); 3930 3931 G1Policy* policy = g1h->g1_policy(); 3932 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 3933 3934 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 3935 } 3936 }; 3937 3938 G1CollectionSet* _collection_set; 3939 G1SerialFreeCollectionSetClosure _cl; 3940 const size_t* _surviving_young_words; 3941 3942 size_t _rs_lengths; 3943 3944 volatile jint _serial_work_claim; 3945 3946 struct WorkItem { 3947 uint region_idx; 3948 bool is_young; 3949 bool evacuation_failed; 3950 3951 WorkItem(HeapRegion* r) { 3952 region_idx = r->hrm_index(); 3953 is_young = r->is_young(); 3954 evacuation_failed = r->evacuation_failed(); 3955 } 3956 }; 3957 3958 volatile size_t _parallel_work_claim; 3959 size_t _num_work_items; 3960 WorkItem* _work_items; 3961 3962 void do_serial_work() { 3963 // Need to grab the lock to be allowed to modify the old region list. 3964 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 3965 _collection_set->iterate(&_cl); 3966 } 3967 3968 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 3969 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 3970 3971 HeapRegion* r = g1h->region_at(region_idx); 3972 assert(!g1h->is_on_master_free_list(r), "sanity"); 3973 3974 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 3975 3976 if (!is_young) { 3977 g1h->_hot_card_cache->reset_card_counts(r); 3978 } 3979 3980 if (!evacuation_failed) { 3981 r->rem_set()->clear_locked(); 3982 } 3983 } 3984 3985 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 3986 private: 3987 size_t _cur_idx; 3988 WorkItem* _work_items; 3989 public: 3990 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 3991 3992 virtual bool do_heap_region(HeapRegion* r) { 3993 _work_items[_cur_idx++] = WorkItem(r); 3994 return false; 3995 } 3996 }; 3997 3998 void prepare_work() { 3999 G1PrepareFreeCollectionSetClosure cl(_work_items); 4000 _collection_set->iterate(&cl); 4001 } 4002 4003 void complete_work() { 4004 _cl.complete_work(); 4005 4006 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4007 policy->record_max_rs_lengths(_rs_lengths); 4008 policy->cset_regions_freed(); 4009 } 4010 public: 4011 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4012 AbstractGangTask("G1 Free Collection Set"), 4013 _collection_set(collection_set), 4014 _cl(evacuation_info, surviving_young_words), 4015 _surviving_young_words(surviving_young_words), 4016 _rs_lengths(0), 4017 _serial_work_claim(0), 4018 _parallel_work_claim(0), 4019 _num_work_items(collection_set->region_length()), 4020 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4021 prepare_work(); 4022 } 4023 4024 ~G1FreeCollectionSetTask() { 4025 complete_work(); 4026 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4027 } 4028 4029 // Chunk size for work distribution. The chosen value has been determined experimentally 4030 // to be a good tradeoff between overhead and achievable parallelism. 4031 static uint chunk_size() { return 32; } 4032 4033 virtual void work(uint worker_id) { 4034 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4035 4036 // Claim serial work. 4037 if (_serial_work_claim == 0) { 4038 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4039 if (value == 0) { 4040 double serial_time = os::elapsedTime(); 4041 do_serial_work(); 4042 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4043 } 4044 } 4045 4046 // Start parallel work. 4047 double young_time = 0.0; 4048 bool has_young_time = false; 4049 double non_young_time = 0.0; 4050 bool has_non_young_time = false; 4051 4052 while (true) { 4053 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4054 size_t cur = end - chunk_size(); 4055 4056 if (cur >= _num_work_items) { 4057 break; 4058 } 4059 4060 EventGCPhaseParallel event; 4061 double start_time = os::elapsedTime(); 4062 4063 end = MIN2(end, _num_work_items); 4064 4065 for (; cur < end; cur++) { 4066 bool is_young = _work_items[cur].is_young; 4067 4068 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4069 4070 double end_time = os::elapsedTime(); 4071 double time_taken = end_time - start_time; 4072 if (is_young) { 4073 young_time += time_taken; 4074 has_young_time = true; 4075 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet)); 4076 } else { 4077 non_young_time += time_taken; 4078 has_non_young_time = true; 4079 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet)); 4080 } 4081 start_time = end_time; 4082 } 4083 } 4084 4085 if (has_young_time) { 4086 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4087 } 4088 if (has_non_young_time) { 4089 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4090 } 4091 } 4092 }; 4093 4094 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4095 _eden.clear(); 4096 4097 double free_cset_start_time = os::elapsedTime(); 4098 4099 { 4100 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4101 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4102 4103 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4104 4105 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4106 cl.name(), 4107 num_workers, 4108 _collection_set.region_length()); 4109 workers()->run_task(&cl, num_workers); 4110 } 4111 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4112 4113 collection_set->clear(); 4114 } 4115 4116 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4117 private: 4118 FreeRegionList* _free_region_list; 4119 HeapRegionSet* _proxy_set; 4120 uint _humongous_objects_reclaimed; 4121 uint _humongous_regions_reclaimed; 4122 size_t _freed_bytes; 4123 public: 4124 4125 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4126 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4127 } 4128 4129 virtual bool do_heap_region(HeapRegion* r) { 4130 if (!r->is_starts_humongous()) { 4131 return false; 4132 } 4133 4134 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4135 4136 oop obj = (oop)r->bottom(); 4137 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4138 4139 // The following checks whether the humongous object is live are sufficient. 4140 // The main additional check (in addition to having a reference from the roots 4141 // or the young gen) is whether the humongous object has a remembered set entry. 4142 // 4143 // A humongous object cannot be live if there is no remembered set for it 4144 // because: 4145 // - there can be no references from within humongous starts regions referencing 4146 // the object because we never allocate other objects into them. 4147 // (I.e. there are no intra-region references that may be missed by the 4148 // remembered set) 4149 // - as soon there is a remembered set entry to the humongous starts region 4150 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4151 // until the end of a concurrent mark. 4152 // 4153 // It is not required to check whether the object has been found dead by marking 4154 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4155 // all objects allocated during that time are considered live. 4156 // SATB marking is even more conservative than the remembered set. 4157 // So if at this point in the collection there is no remembered set entry, 4158 // nobody has a reference to it. 4159 // At the start of collection we flush all refinement logs, and remembered sets 4160 // are completely up-to-date wrt to references to the humongous object. 4161 // 4162 // Other implementation considerations: 4163 // - never consider object arrays at this time because they would pose 4164 // considerable effort for cleaning up the the remembered sets. This is 4165 // required because stale remembered sets might reference locations that 4166 // are currently allocated into. 4167 uint region_idx = r->hrm_index(); 4168 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4169 !r->rem_set()->is_empty()) { 4170 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", 4171 region_idx, 4172 (size_t)obj->size() * HeapWordSize, 4173 p2i(r->bottom()), 4174 r->rem_set()->occupied(), 4175 r->rem_set()->strong_code_roots_list_length(), 4176 next_bitmap->is_marked(r->bottom()), 4177 g1h->is_humongous_reclaim_candidate(region_idx), 4178 obj->is_typeArray() 4179 ); 4180 return false; 4181 } 4182 4183 guarantee(obj->is_typeArray(), 4184 "Only eagerly reclaiming type arrays is supported, but the object " 4185 PTR_FORMAT " is not.", p2i(r->bottom())); 4186 4187 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", 4188 region_idx, 4189 (size_t)obj->size() * HeapWordSize, 4190 p2i(r->bottom()), 4191 r->rem_set()->occupied(), 4192 r->rem_set()->strong_code_roots_list_length(), 4193 next_bitmap->is_marked(r->bottom()), 4194 g1h->is_humongous_reclaim_candidate(region_idx), 4195 obj->is_typeArray() 4196 ); 4197 4198 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4199 cm->humongous_object_eagerly_reclaimed(r); 4200 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4201 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4202 region_idx, 4203 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4204 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4205 _humongous_objects_reclaimed++; 4206 do { 4207 HeapRegion* next = g1h->next_region_in_humongous(r); 4208 _freed_bytes += r->used(); 4209 r->set_containing_set(NULL); 4210 _humongous_regions_reclaimed++; 4211 g1h->free_humongous_region(r, _free_region_list); 4212 r = next; 4213 } while (r != NULL); 4214 4215 return false; 4216 } 4217 4218 uint humongous_objects_reclaimed() { 4219 return _humongous_objects_reclaimed; 4220 } 4221 4222 uint humongous_regions_reclaimed() { 4223 return _humongous_regions_reclaimed; 4224 } 4225 4226 size_t bytes_freed() const { 4227 return _freed_bytes; 4228 } 4229 }; 4230 4231 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4232 assert_at_safepoint_on_vm_thread(); 4233 4234 if (!G1EagerReclaimHumongousObjects || 4235 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4236 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4237 return; 4238 } 4239 4240 double start_time = os::elapsedTime(); 4241 4242 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4243 4244 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4245 heap_region_iterate(&cl); 4246 4247 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4248 4249 G1HRPrinter* hrp = hr_printer(); 4250 if (hrp->is_active()) { 4251 FreeRegionListIterator iter(&local_cleanup_list); 4252 while (iter.more_available()) { 4253 HeapRegion* hr = iter.get_next(); 4254 hrp->cleanup(hr); 4255 } 4256 } 4257 4258 prepend_to_freelist(&local_cleanup_list); 4259 decrement_summary_bytes(cl.bytes_freed()); 4260 4261 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4262 cl.humongous_objects_reclaimed()); 4263 } 4264 4265 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4266 public: 4267 virtual bool do_heap_region(HeapRegion* r) { 4268 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4269 G1CollectedHeap::heap()->clear_in_cset(r); 4270 r->set_young_index_in_cset(-1); 4271 return false; 4272 } 4273 }; 4274 4275 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4276 G1AbandonCollectionSetClosure cl; 4277 collection_set->iterate(&cl); 4278 4279 collection_set->clear(); 4280 collection_set->stop_incremental_building(); 4281 } 4282 4283 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4284 return _allocator->is_retained_old_region(hr); 4285 } 4286 4287 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4288 _eden.add(hr); 4289 _g1_policy->set_region_eden(hr); 4290 } 4291 4292 #ifdef ASSERT 4293 4294 class NoYoungRegionsClosure: public HeapRegionClosure { 4295 private: 4296 bool _success; 4297 public: 4298 NoYoungRegionsClosure() : _success(true) { } 4299 bool do_heap_region(HeapRegion* r) { 4300 if (r->is_young()) { 4301 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4302 p2i(r->bottom()), p2i(r->end())); 4303 _success = false; 4304 } 4305 return false; 4306 } 4307 bool success() { return _success; } 4308 }; 4309 4310 bool G1CollectedHeap::check_young_list_empty() { 4311 bool ret = (young_regions_count() == 0); 4312 4313 NoYoungRegionsClosure closure; 4314 heap_region_iterate(&closure); 4315 ret = ret && closure.success(); 4316 4317 return ret; 4318 } 4319 4320 #endif // ASSERT 4321 4322 class TearDownRegionSetsClosure : public HeapRegionClosure { 4323 HeapRegionSet *_old_set; 4324 4325 public: 4326 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4327 4328 bool do_heap_region(HeapRegion* r) { 4329 if (r->is_old()) { 4330 _old_set->remove(r); 4331 } else if(r->is_young()) { 4332 r->uninstall_surv_rate_group(); 4333 } else { 4334 // We ignore free regions, we'll empty the free list afterwards. 4335 // We ignore humongous and archive regions, we're not tearing down these 4336 // sets. 4337 assert(r->is_archive() || r->is_free() || r->is_humongous(), 4338 "it cannot be another type"); 4339 } 4340 return false; 4341 } 4342 4343 ~TearDownRegionSetsClosure() { 4344 assert(_old_set->is_empty(), "post-condition"); 4345 } 4346 }; 4347 4348 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4349 assert_at_safepoint_on_vm_thread(); 4350 4351 if (!free_list_only) { 4352 TearDownRegionSetsClosure cl(&_old_set); 4353 heap_region_iterate(&cl); 4354 4355 // Note that emptying the _young_list is postponed and instead done as 4356 // the first step when rebuilding the regions sets again. The reason for 4357 // this is that during a full GC string deduplication needs to know if 4358 // a collected region was young or old when the full GC was initiated. 4359 } 4360 _hrm.remove_all_free_regions(); 4361 } 4362 4363 void G1CollectedHeap::increase_used(size_t bytes) { 4364 _summary_bytes_used += bytes; 4365 } 4366 4367 void G1CollectedHeap::decrease_used(size_t bytes) { 4368 assert(_summary_bytes_used >= bytes, 4369 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4370 _summary_bytes_used, bytes); 4371 _summary_bytes_used -= bytes; 4372 } 4373 4374 void G1CollectedHeap::set_used(size_t bytes) { 4375 _summary_bytes_used = bytes; 4376 } 4377 4378 class RebuildRegionSetsClosure : public HeapRegionClosure { 4379 private: 4380 bool _free_list_only; 4381 4382 HeapRegionSet* _old_set; 4383 HeapRegionManager* _hrm; 4384 4385 size_t _total_used; 4386 4387 public: 4388 RebuildRegionSetsClosure(bool free_list_only, 4389 HeapRegionSet* old_set, 4390 HeapRegionManager* hrm) : 4391 _free_list_only(free_list_only), 4392 _old_set(old_set), _hrm(hrm), _total_used(0) { 4393 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4394 if (!free_list_only) { 4395 assert(_old_set->is_empty(), "pre-condition"); 4396 } 4397 } 4398 4399 bool do_heap_region(HeapRegion* r) { 4400 // After full GC, no region should have a remembered set. 4401 r->rem_set()->clear(true); 4402 if (r->is_empty()) { 4403 // Add free regions to the free list 4404 r->set_free(); 4405 _hrm->insert_into_free_list(r); 4406 } else if (!_free_list_only) { 4407 4408 if (r->is_archive() || r->is_humongous()) { 4409 // We ignore archive and humongous regions. We left these sets unchanged. 4410 } else { 4411 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4412 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such. 4413 r->move_to_old(); 4414 _old_set->add(r); 4415 } 4416 _total_used += r->used(); 4417 } 4418 4419 return false; 4420 } 4421 4422 size_t total_used() { 4423 return _total_used; 4424 } 4425 }; 4426 4427 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4428 assert_at_safepoint_on_vm_thread(); 4429 4430 if (!free_list_only) { 4431 _eden.clear(); 4432 _survivor.clear(); 4433 } 4434 4435 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 4436 heap_region_iterate(&cl); 4437 4438 if (!free_list_only) { 4439 set_used(cl.total_used()); 4440 if (_archive_allocator != NULL) { 4441 _archive_allocator->clear_used(); 4442 } 4443 } 4444 assert(used_unlocked() == recalculate_used(), 4445 "inconsistent used_unlocked(), " 4446 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4447 used_unlocked(), recalculate_used()); 4448 } 4449 4450 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4451 HeapRegion* hr = heap_region_containing(p); 4452 return hr->is_in(p); 4453 } 4454 4455 // Methods for the mutator alloc region 4456 4457 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4458 bool force) { 4459 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4460 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4461 if (force || should_allocate) { 4462 HeapRegion* new_alloc_region = new_region(word_size, 4463 false /* is_old */, 4464 false /* do_expand */); 4465 if (new_alloc_region != NULL) { 4466 set_region_short_lived_locked(new_alloc_region); 4467 _hr_printer.alloc(new_alloc_region, !should_allocate); 4468 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4469 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4470 return new_alloc_region; 4471 } 4472 } 4473 return NULL; 4474 } 4475 4476 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4477 size_t allocated_bytes) { 4478 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4479 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4480 4481 collection_set()->add_eden_region(alloc_region); 4482 increase_used(allocated_bytes); 4483 _hr_printer.retire(alloc_region); 4484 // We update the eden sizes here, when the region is retired, 4485 // instead of when it's allocated, since this is the point that its 4486 // used space has been recorded in _summary_bytes_used. 4487 g1mm()->update_eden_size(); 4488 } 4489 4490 // Methods for the GC alloc regions 4491 4492 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4493 if (dest.is_old()) { 4494 return true; 4495 } else { 4496 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4497 } 4498 } 4499 4500 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4501 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4502 4503 if (!has_more_regions(dest)) { 4504 return NULL; 4505 } 4506 4507 const bool is_survivor = dest.is_young(); 4508 4509 HeapRegion* new_alloc_region = new_region(word_size, 4510 !is_survivor, 4511 true /* do_expand */); 4512 if (new_alloc_region != NULL) { 4513 if (is_survivor) { 4514 new_alloc_region->set_survivor(); 4515 _survivor.add(new_alloc_region); 4516 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4517 } else { 4518 new_alloc_region->set_old(); 4519 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4520 } 4521 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4522 _hr_printer.alloc(new_alloc_region); 4523 bool during_im = collector_state()->in_initial_mark_gc(); 4524 new_alloc_region->note_start_of_copying(during_im); 4525 return new_alloc_region; 4526 } 4527 return NULL; 4528 } 4529 4530 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4531 size_t allocated_bytes, 4532 InCSetState dest) { 4533 bool during_im = collector_state()->in_initial_mark_gc(); 4534 alloc_region->note_end_of_copying(during_im); 4535 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4536 if (dest.is_old()) { 4537 old_set_add(alloc_region); 4538 } 4539 _hr_printer.retire(alloc_region); 4540 } 4541 4542 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4543 bool expanded = false; 4544 uint index = _hrm.find_highest_free(&expanded); 4545 4546 if (index != G1_NO_HRM_INDEX) { 4547 if (expanded) { 4548 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4549 HeapRegion::GrainWords * HeapWordSize); 4550 } 4551 _hrm.allocate_free_regions_starting_at(index, 1); 4552 return region_at(index); 4553 } 4554 return NULL; 4555 } 4556 4557 // Optimized nmethod scanning 4558 4559 class RegisterNMethodOopClosure: public OopClosure { 4560 G1CollectedHeap* _g1h; 4561 nmethod* _nm; 4562 4563 template <class T> void do_oop_work(T* p) { 4564 T heap_oop = RawAccess<>::oop_load(p); 4565 if (!CompressedOops::is_null(heap_oop)) { 4566 oop obj = CompressedOops::decode_not_null(heap_oop); 4567 HeapRegion* hr = _g1h->heap_region_containing(obj); 4568 assert(!hr->is_continues_humongous(), 4569 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4570 " starting at " HR_FORMAT, 4571 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4572 4573 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4574 hr->add_strong_code_root_locked(_nm); 4575 } 4576 } 4577 4578 public: 4579 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4580 _g1h(g1h), _nm(nm) {} 4581 4582 void do_oop(oop* p) { do_oop_work(p); } 4583 void do_oop(narrowOop* p) { do_oop_work(p); } 4584 }; 4585 4586 class UnregisterNMethodOopClosure: public OopClosure { 4587 G1CollectedHeap* _g1h; 4588 nmethod* _nm; 4589 4590 template <class T> void do_oop_work(T* p) { 4591 T heap_oop = RawAccess<>::oop_load(p); 4592 if (!CompressedOops::is_null(heap_oop)) { 4593 oop obj = CompressedOops::decode_not_null(heap_oop); 4594 HeapRegion* hr = _g1h->heap_region_containing(obj); 4595 assert(!hr->is_continues_humongous(), 4596 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4597 " starting at " HR_FORMAT, 4598 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4599 4600 hr->remove_strong_code_root(_nm); 4601 } 4602 } 4603 4604 public: 4605 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4606 _g1h(g1h), _nm(nm) {} 4607 4608 void do_oop(oop* p) { do_oop_work(p); } 4609 void do_oop(narrowOop* p) { do_oop_work(p); } 4610 }; 4611 4612 // Returns true if the reference points to an object that 4613 // can move in an incremental collection. 4614 bool G1CollectedHeap::is_scavengable(oop obj) { 4615 HeapRegion* hr = heap_region_containing(obj); 4616 return !hr->is_pinned(); 4617 } 4618 4619 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4620 guarantee(nm != NULL, "sanity"); 4621 RegisterNMethodOopClosure reg_cl(this, nm); 4622 nm->oops_do(®_cl); 4623 } 4624 4625 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4626 guarantee(nm != NULL, "sanity"); 4627 UnregisterNMethodOopClosure reg_cl(this, nm); 4628 nm->oops_do(®_cl, true); 4629 } 4630 4631 void G1CollectedHeap::purge_code_root_memory() { 4632 double purge_start = os::elapsedTime(); 4633 G1CodeRootSet::purge(); 4634 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4635 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4636 } 4637 4638 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4639 G1CollectedHeap* _g1h; 4640 4641 public: 4642 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4643 _g1h(g1h) {} 4644 4645 void do_code_blob(CodeBlob* cb) { 4646 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4647 if (nm == NULL) { 4648 return; 4649 } 4650 4651 if (ScavengeRootsInCode) { 4652 _g1h->register_nmethod(nm); 4653 } 4654 } 4655 }; 4656 4657 void G1CollectedHeap::rebuild_strong_code_roots() { 4658 RebuildStrongCodeRootClosure blob_cl(this); 4659 CodeCache::blobs_do(&blob_cl); 4660 } 4661 4662 void G1CollectedHeap::initialize_serviceability() { 4663 _g1mm->initialize_serviceability(); 4664 } 4665 4666 MemoryUsage G1CollectedHeap::memory_usage() { 4667 return _g1mm->memory_usage(); 4668 } 4669 4670 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4671 return _g1mm->memory_managers(); 4672 } 4673 4674 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 4675 return _g1mm->memory_pools(); 4676 }