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/metadataOnStackMark.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.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/g1StringDedup.hpp" 56 #include "gc/g1/g1ThreadLocalData.hpp" 57 #include "gc/g1/g1YCTypes.hpp" 58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 59 #include "gc/g1/heapRegion.inline.hpp" 60 #include "gc/g1/heapRegionRemSet.hpp" 61 #include "gc/g1/heapRegionSet.inline.hpp" 62 #include "gc/g1/vm_operations_g1.hpp" 63 #include "gc/shared/adaptiveSizePolicy.hpp" 64 #include "gc/shared/gcHeapSummary.hpp" 65 #include "gc/shared/gcId.hpp" 66 #include "gc/shared/gcLocker.hpp" 67 #include "gc/shared/gcTimer.hpp" 68 #include "gc/shared/gcTrace.hpp" 69 #include "gc/shared/gcTraceTime.inline.hpp" 70 #include "gc/shared/generationSpec.hpp" 71 #include "gc/shared/isGCActiveMark.hpp" 72 #include "gc/shared/preservedMarks.inline.hpp" 73 #include "gc/shared/suspendibleThreadSet.hpp" 74 #include "gc/shared/referenceProcessor.inline.hpp" 75 #include "gc/shared/taskqueue.inline.hpp" 76 #include "gc/shared/weakProcessor.hpp" 77 #include "logging/log.hpp" 78 #include "memory/allocation.hpp" 79 #include "memory/iterator.hpp" 80 #include "memory/resourceArea.hpp" 81 #include "oops/access.inline.hpp" 82 #include "oops/compressedOops.inline.hpp" 83 #include "oops/oop.inline.hpp" 84 #include "prims/resolvedMethodTable.hpp" 85 #include "runtime/atomic.hpp" 86 #include "runtime/handles.inline.hpp" 87 #include "runtime/init.hpp" 88 #include "runtime/orderAccess.inline.hpp" 89 #include "runtime/threadSMR.hpp" 90 #include "runtime/vmThread.hpp" 91 #include "utilities/align.hpp" 92 #include "utilities/globalDefinitions.hpp" 93 #include "utilities/stack.inline.hpp" 94 95 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0; 96 97 // INVARIANTS/NOTES 98 // 99 // All allocation activity covered by the G1CollectedHeap interface is 100 // serialized by acquiring the HeapLock. This happens in mem_allocate 101 // and allocate_new_tlab, which are the "entry" points to the 102 // allocation code from the rest of the JVM. (Note that this does not 103 // apply to TLAB allocation, which is not part of this interface: it 104 // is done by clients of this interface.) 105 106 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure { 107 private: 108 size_t _num_dirtied; 109 G1CollectedHeap* _g1h; 110 G1CardTable* _g1_ct; 111 112 HeapRegion* region_for_card(jbyte* card_ptr) const { 113 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr)); 114 } 115 116 bool will_become_free(HeapRegion* hr) const { 117 // A region will be freed by free_collection_set if the region is in the 118 // collection set and has not had an evacuation failure. 119 return _g1h->is_in_cset(hr) && !hr->evacuation_failed(); 120 } 121 122 public: 123 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(), 124 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { } 125 126 bool do_card_ptr(jbyte* card_ptr, uint worker_i) { 127 HeapRegion* hr = region_for_card(card_ptr); 128 129 // Should only dirty cards in regions that won't be freed. 130 if (!will_become_free(hr)) { 131 *card_ptr = G1CardTable::dirty_card_val(); 132 _num_dirtied++; 133 } 134 135 return true; 136 } 137 138 size_t num_dirtied() const { return _num_dirtied; } 139 }; 140 141 142 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) { 143 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions); 144 } 145 146 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 147 // The from card cache is not the memory that is actually committed. So we cannot 148 // take advantage of the zero_filled parameter. 149 reset_from_card_cache(start_idx, num_regions); 150 } 151 152 153 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index, 154 MemRegion mr) { 155 return new HeapRegion(hrs_index, bot(), mr); 156 } 157 158 // Private methods. 159 160 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) { 161 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords, 162 "the only time we use this to allocate a humongous region is " 163 "when we are allocating a single humongous region"); 164 165 HeapRegion* res = _hrm.allocate_free_region(is_old); 166 167 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) { 168 // Currently, only attempts to allocate GC alloc regions set 169 // do_expand to true. So, we should only reach here during a 170 // safepoint. If this assumption changes we might have to 171 // reconsider the use of _expand_heap_after_alloc_failure. 172 assert(SafepointSynchronize::is_at_safepoint(), "invariant"); 173 174 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B", 175 word_size * HeapWordSize); 176 177 if (expand(word_size * HeapWordSize)) { 178 // Given that expand() succeeded in expanding the heap, and we 179 // always expand the heap by an amount aligned to the heap 180 // region size, the free list should in theory not be empty. 181 // In either case allocate_free_region() will check for NULL. 182 res = _hrm.allocate_free_region(is_old); 183 } else { 184 _expand_heap_after_alloc_failure = false; 185 } 186 } 187 return res; 188 } 189 190 HeapWord* 191 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first, 192 uint num_regions, 193 size_t word_size) { 194 assert(first != G1_NO_HRM_INDEX, "pre-condition"); 195 assert(is_humongous(word_size), "word_size should be humongous"); 196 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition"); 197 198 // Index of last region in the series. 199 uint last = first + num_regions - 1; 200 201 // We need to initialize the region(s) we just discovered. This is 202 // a bit tricky given that it can happen concurrently with 203 // refinement threads refining cards on these regions and 204 // potentially wanting to refine the BOT as they are scanning 205 // those cards (this can happen shortly after a cleanup; see CR 206 // 6991377). So we have to set up the region(s) carefully and in 207 // a specific order. 208 209 // The word size sum of all the regions we will allocate. 210 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords; 211 assert(word_size <= word_size_sum, "sanity"); 212 213 // This will be the "starts humongous" region. 214 HeapRegion* first_hr = region_at(first); 215 // The header of the new object will be placed at the bottom of 216 // the first region. 217 HeapWord* new_obj = first_hr->bottom(); 218 // This will be the new top of the new object. 219 HeapWord* obj_top = new_obj + word_size; 220 221 // First, we need to zero the header of the space that we will be 222 // allocating. When we update top further down, some refinement 223 // threads might try to scan the region. By zeroing the header we 224 // ensure that any thread that will try to scan the region will 225 // come across the zero klass word and bail out. 226 // 227 // NOTE: It would not have been correct to have used 228 // CollectedHeap::fill_with_object() and make the space look like 229 // an int array. The thread that is doing the allocation will 230 // later update the object header to a potentially different array 231 // type and, for a very short period of time, the klass and length 232 // fields will be inconsistent. This could cause a refinement 233 // thread to calculate the object size incorrectly. 234 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); 235 236 // Next, pad out the unused tail of the last region with filler 237 // objects, for improved usage accounting. 238 // How many words we use for filler objects. 239 size_t word_fill_size = word_size_sum - word_size; 240 241 // How many words memory we "waste" which cannot hold a filler object. 242 size_t words_not_fillable = 0; 243 244 if (word_fill_size >= min_fill_size()) { 245 fill_with_objects(obj_top, word_fill_size); 246 } else if (word_fill_size > 0) { 247 // We have space to fill, but we cannot fit an object there. 248 words_not_fillable = word_fill_size; 249 word_fill_size = 0; 250 } 251 252 // We will set up the first region as "starts humongous". This 253 // will also update the BOT covering all the regions to reflect 254 // that there is a single object that starts at the bottom of the 255 // first region. 256 first_hr->set_starts_humongous(obj_top, word_fill_size); 257 _g1_policy->remset_tracker()->update_at_allocate(first_hr); 258 // Then, if there are any, we will set up the "continues 259 // humongous" regions. 260 HeapRegion* hr = NULL; 261 for (uint i = first + 1; i <= last; ++i) { 262 hr = region_at(i); 263 hr->set_continues_humongous(first_hr); 264 _g1_policy->remset_tracker()->update_at_allocate(hr); 265 } 266 267 // Up to this point no concurrent thread would have been able to 268 // do any scanning on any region in this series. All the top 269 // fields still point to bottom, so the intersection between 270 // [bottom,top] and [card_start,card_end] will be empty. Before we 271 // update the top fields, we'll do a storestore to make sure that 272 // no thread sees the update to top before the zeroing of the 273 // object header and the BOT initialization. 274 OrderAccess::storestore(); 275 276 // Now, we will update the top fields of the "continues humongous" 277 // regions except the last one. 278 for (uint i = first; i < last; ++i) { 279 hr = region_at(i); 280 hr->set_top(hr->end()); 281 } 282 283 hr = region_at(last); 284 // If we cannot fit a filler object, we must set top to the end 285 // of the humongous object, otherwise we cannot iterate the heap 286 // and the BOT will not be complete. 287 hr->set_top(hr->end() - words_not_fillable); 288 289 assert(hr->bottom() < obj_top && obj_top <= hr->end(), 290 "obj_top should be in last region"); 291 292 _verifier->check_bitmaps("Humongous Region Allocation", first_hr); 293 294 assert(words_not_fillable == 0 || 295 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(), 296 "Miscalculation in humongous allocation"); 297 298 increase_used((word_size_sum - words_not_fillable) * HeapWordSize); 299 300 for (uint i = first; i <= last; ++i) { 301 hr = region_at(i); 302 _humongous_set.add(hr); 303 _hr_printer.alloc(hr); 304 } 305 306 return new_obj; 307 } 308 309 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) { 310 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size); 311 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords; 312 } 313 314 // If could fit into free regions w/o expansion, try. 315 // Otherwise, if can expand, do so. 316 // Otherwise, if using ex regions might help, try with ex given back. 317 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) { 318 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 319 320 _verifier->verify_region_sets_optional(); 321 322 uint first = G1_NO_HRM_INDEX; 323 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size); 324 325 if (obj_regions == 1) { 326 // Only one region to allocate, try to use a fast path by directly allocating 327 // from the free lists. Do not try to expand here, we will potentially do that 328 // later. 329 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */); 330 if (hr != NULL) { 331 first = hr->hrm_index(); 332 } 333 } else { 334 // Policy: Try only empty regions (i.e. already committed first). Maybe we 335 // are lucky enough to find some. 336 first = _hrm.find_contiguous_only_empty(obj_regions); 337 if (first != G1_NO_HRM_INDEX) { 338 _hrm.allocate_free_regions_starting_at(first, obj_regions); 339 } 340 } 341 342 if (first == G1_NO_HRM_INDEX) { 343 // Policy: We could not find enough regions for the humongous object in the 344 // free list. Look through the heap to find a mix of free and uncommitted regions. 345 // If so, try expansion. 346 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions); 347 if (first != G1_NO_HRM_INDEX) { 348 // We found something. Make sure these regions are committed, i.e. expand 349 // the heap. Alternatively we could do a defragmentation GC. 350 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B", 351 word_size * HeapWordSize); 352 353 _hrm.expand_at(first, obj_regions, workers()); 354 g1_policy()->record_new_heap_size(num_regions()); 355 356 #ifdef ASSERT 357 for (uint i = first; i < first + obj_regions; ++i) { 358 HeapRegion* hr = region_at(i); 359 assert(hr->is_free(), "sanity"); 360 assert(hr->is_empty(), "sanity"); 361 assert(is_on_master_free_list(hr), "sanity"); 362 } 363 #endif 364 _hrm.allocate_free_regions_starting_at(first, obj_regions); 365 } else { 366 // Policy: Potentially trigger a defragmentation GC. 367 } 368 } 369 370 HeapWord* result = NULL; 371 if (first != G1_NO_HRM_INDEX) { 372 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size); 373 assert(result != NULL, "it should always return a valid result"); 374 375 // A successful humongous object allocation changes the used space 376 // information of the old generation so we need to recalculate the 377 // sizes and update the jstat counters here. 378 g1mm()->update_sizes(); 379 } 380 381 _verifier->verify_region_sets_optional(); 382 383 return result; 384 } 385 386 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) { 387 assert_heap_not_locked_and_not_at_safepoint(); 388 assert(!is_humongous(word_size), "we do not allow humongous TLABs"); 389 390 return attempt_allocation(word_size); 391 } 392 393 HeapWord* 394 G1CollectedHeap::mem_allocate(size_t word_size, 395 bool* gc_overhead_limit_was_exceeded) { 396 assert_heap_not_locked_and_not_at_safepoint(); 397 398 if (is_humongous(word_size)) { 399 return attempt_allocation_humongous(word_size); 400 } 401 return attempt_allocation(word_size); 402 } 403 404 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) { 405 ResourceMark rm; // For retrieving the thread names in log messages. 406 407 // Make sure you read the note in attempt_allocation_humongous(). 408 409 assert_heap_not_locked_and_not_at_safepoint(); 410 assert(!is_humongous(word_size), "attempt_allocation_slow() should not " 411 "be called for humongous allocation requests"); 412 413 // We should only get here after the first-level allocation attempt 414 // (attempt_allocation()) failed to allocate. 415 416 // We will loop until a) we manage to successfully perform the 417 // allocation or b) we successfully schedule a collection which 418 // fails to perform the allocation. b) is the only case when we'll 419 // return NULL. 420 HeapWord* result = NULL; 421 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 422 bool should_try_gc; 423 uint gc_count_before; 424 425 { 426 MutexLockerEx x(Heap_lock); 427 result = _allocator->attempt_allocation_locked(word_size); 428 if (result != NULL) { 429 return result; 430 } 431 432 // If the GCLocker is active and we are bound for a GC, try expanding young gen. 433 // This is different to when only GCLocker::needs_gc() is set: try to avoid 434 // waiting because the GCLocker is active to not wait too long. 435 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) { 436 // No need for an ergo message here, can_expand_young_list() does this when 437 // it returns true. 438 result = _allocator->attempt_allocation_force(word_size); 439 if (result != NULL) { 440 return result; 441 } 442 } 443 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 444 // the GCLocker initiated GC has been performed and then retry. This includes 445 // the case when the GC Locker is not active but has not been performed. 446 should_try_gc = !GCLocker::needs_gc(); 447 // Read the GC count while still holding the Heap_lock. 448 gc_count_before = total_collections(); 449 } 450 451 if (should_try_gc) { 452 bool succeeded; 453 result = do_collection_pause(word_size, gc_count_before, &succeeded, 454 GCCause::_g1_inc_collection_pause); 455 if (result != NULL) { 456 assert(succeeded, "only way to get back a non-NULL result"); 457 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 458 Thread::current()->name(), p2i(result)); 459 return result; 460 } 461 462 if (succeeded) { 463 // We successfully scheduled a collection which failed to allocate. No 464 // point in trying to allocate further. We'll just return NULL. 465 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 466 SIZE_FORMAT " words", Thread::current()->name(), word_size); 467 return NULL; 468 } 469 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words", 470 Thread::current()->name(), word_size); 471 } else { 472 // Failed to schedule a collection. 473 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 474 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 475 SIZE_FORMAT " words", Thread::current()->name(), word_size); 476 return NULL; 477 } 478 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 479 // The GCLocker is either active or the GCLocker initiated 480 // GC has not yet been performed. Stall until it is and 481 // then retry the allocation. 482 GCLocker::stall_until_clear(); 483 gclocker_retry_count += 1; 484 } 485 486 // We can reach here if we were unsuccessful in scheduling a 487 // collection (because another thread beat us to it) or if we were 488 // stalled due to the GC locker. In either can we should retry the 489 // allocation attempt in case another thread successfully 490 // performed a collection and reclaimed enough space. We do the 491 // first attempt (without holding the Heap_lock) here and the 492 // follow-on attempt will be at the start of the next loop 493 // iteration (after taking the Heap_lock). 494 495 result = _allocator->attempt_allocation(word_size); 496 if (result != NULL) { 497 return result; 498 } 499 500 // Give a warning if we seem to be looping forever. 501 if ((QueuedAllocationWarningCount > 0) && 502 (try_count % QueuedAllocationWarningCount == 0)) { 503 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 504 Thread::current()->name(), try_count, word_size); 505 } 506 } 507 508 ShouldNotReachHere(); 509 return NULL; 510 } 511 512 void G1CollectedHeap::begin_archive_alloc_range(bool open) { 513 assert_at_safepoint_on_vm_thread(); 514 if (_archive_allocator == NULL) { 515 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open); 516 } 517 } 518 519 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) { 520 // Allocations in archive regions cannot be of a size that would be considered 521 // humongous even for a minimum-sized region, because G1 region sizes/boundaries 522 // may be different at archive-restore time. 523 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words()); 524 } 525 526 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) { 527 assert_at_safepoint_on_vm_thread(); 528 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 529 if (is_archive_alloc_too_large(word_size)) { 530 return NULL; 531 } 532 return _archive_allocator->archive_mem_allocate(word_size); 533 } 534 535 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 536 size_t end_alignment_in_bytes) { 537 assert_at_safepoint_on_vm_thread(); 538 assert(_archive_allocator != NULL, "_archive_allocator not initialized"); 539 540 // Call complete_archive to do the real work, filling in the MemRegion 541 // array with the archive regions. 542 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes); 543 delete _archive_allocator; 544 _archive_allocator = NULL; 545 } 546 547 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) { 548 assert(ranges != NULL, "MemRegion array NULL"); 549 assert(count != 0, "No MemRegions provided"); 550 MemRegion reserved = _hrm.reserved(); 551 for (size_t i = 0; i < count; i++) { 552 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) { 553 return false; 554 } 555 } 556 return true; 557 } 558 559 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, 560 size_t count, 561 bool open) { 562 assert(!is_init_completed(), "Expect to be called at JVM init time"); 563 assert(ranges != NULL, "MemRegion array NULL"); 564 assert(count != 0, "No MemRegions provided"); 565 MutexLockerEx x(Heap_lock); 566 567 MemRegion reserved = _hrm.reserved(); 568 HeapWord* prev_last_addr = NULL; 569 HeapRegion* prev_last_region = NULL; 570 571 // Temporarily disable pretouching of heap pages. This interface is used 572 // when mmap'ing archived heap data in, so pre-touching is wasted. 573 FlagSetting fs(AlwaysPreTouch, false); 574 575 // Enable archive object checking used by G1MarkSweep. We have to let it know 576 // about each archive range, so that objects in those ranges aren't marked. 577 G1ArchiveAllocator::enable_archive_object_check(); 578 579 // For each specified MemRegion range, allocate the corresponding G1 580 // regions and mark them as archive regions. We expect the ranges 581 // in ascending starting address order, without overlap. 582 for (size_t i = 0; i < count; i++) { 583 MemRegion curr_range = ranges[i]; 584 HeapWord* start_address = curr_range.start(); 585 size_t word_size = curr_range.word_size(); 586 HeapWord* last_address = curr_range.last(); 587 size_t commits = 0; 588 589 guarantee(reserved.contains(start_address) && reserved.contains(last_address), 590 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 591 p2i(start_address), p2i(last_address)); 592 guarantee(start_address > prev_last_addr, 593 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 594 p2i(start_address), p2i(prev_last_addr)); 595 prev_last_addr = last_address; 596 597 // Check for ranges that start in the same G1 region in which the previous 598 // range ended, and adjust the start address so we don't try to allocate 599 // the same region again. If the current range is entirely within that 600 // region, skip it, just adjusting the recorded top. 601 HeapRegion* start_region = _hrm.addr_to_region(start_address); 602 if ((prev_last_region != NULL) && (start_region == prev_last_region)) { 603 start_address = start_region->end(); 604 if (start_address > last_address) { 605 increase_used(word_size * HeapWordSize); 606 start_region->set_top(last_address + 1); 607 continue; 608 } 609 start_region->set_top(start_address); 610 curr_range = MemRegion(start_address, last_address + 1); 611 start_region = _hrm.addr_to_region(start_address); 612 } 613 614 // Perform the actual region allocation, exiting if it fails. 615 // Then note how much new space we have allocated. 616 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) { 617 return false; 618 } 619 increase_used(word_size * HeapWordSize); 620 if (commits != 0) { 621 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B", 622 HeapRegion::GrainWords * HeapWordSize * commits); 623 624 } 625 626 // Mark each G1 region touched by the range as archive, add it to 627 // the old set, and set top. 628 HeapRegion* curr_region = _hrm.addr_to_region(start_address); 629 HeapRegion* last_region = _hrm.addr_to_region(last_address); 630 prev_last_region = last_region; 631 632 while (curr_region != NULL) { 633 assert(curr_region->is_empty() && !curr_region->is_pinned(), 634 "Region already in use (index %u)", curr_region->hrm_index()); 635 if (open) { 636 curr_region->set_open_archive(); 637 } else { 638 curr_region->set_closed_archive(); 639 } 640 _hr_printer.alloc(curr_region); 641 _old_set.add(curr_region); 642 HeapWord* top; 643 HeapRegion* next_region; 644 if (curr_region != last_region) { 645 top = curr_region->end(); 646 next_region = _hrm.next_region_in_heap(curr_region); 647 } else { 648 top = last_address + 1; 649 next_region = NULL; 650 } 651 curr_region->set_top(top); 652 curr_region->set_first_dead(top); 653 curr_region->set_end_of_live(top); 654 curr_region = next_region; 655 } 656 657 // Notify mark-sweep of the archive 658 G1ArchiveAllocator::set_range_archive(curr_range, open); 659 } 660 return true; 661 } 662 663 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) { 664 assert(!is_init_completed(), "Expect to be called at JVM init time"); 665 assert(ranges != NULL, "MemRegion array NULL"); 666 assert(count != 0, "No MemRegions provided"); 667 MemRegion reserved = _hrm.reserved(); 668 HeapWord *prev_last_addr = NULL; 669 HeapRegion* prev_last_region = NULL; 670 671 // For each MemRegion, create filler objects, if needed, in the G1 regions 672 // that contain the address range. The address range actually within the 673 // MemRegion will not be modified. That is assumed to have been initialized 674 // elsewhere, probably via an mmap of archived heap data. 675 MutexLockerEx x(Heap_lock); 676 for (size_t i = 0; i < count; i++) { 677 HeapWord* start_address = ranges[i].start(); 678 HeapWord* last_address = ranges[i].last(); 679 680 assert(reserved.contains(start_address) && reserved.contains(last_address), 681 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 682 p2i(start_address), p2i(last_address)); 683 assert(start_address > prev_last_addr, 684 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 685 p2i(start_address), p2i(prev_last_addr)); 686 687 HeapRegion* start_region = _hrm.addr_to_region(start_address); 688 HeapRegion* last_region = _hrm.addr_to_region(last_address); 689 HeapWord* bottom_address = start_region->bottom(); 690 691 // Check for a range beginning in the same region in which the 692 // previous one ended. 693 if (start_region == prev_last_region) { 694 bottom_address = prev_last_addr + 1; 695 } 696 697 // Verify that the regions were all marked as archive regions by 698 // alloc_archive_regions. 699 HeapRegion* curr_region = start_region; 700 while (curr_region != NULL) { 701 guarantee(curr_region->is_archive(), 702 "Expected archive region at index %u", curr_region->hrm_index()); 703 if (curr_region != last_region) { 704 curr_region = _hrm.next_region_in_heap(curr_region); 705 } else { 706 curr_region = NULL; 707 } 708 } 709 710 prev_last_addr = last_address; 711 prev_last_region = last_region; 712 713 // Fill the memory below the allocated range with dummy object(s), 714 // if the region bottom does not match the range start, or if the previous 715 // range ended within the same G1 region, and there is a gap. 716 if (start_address != bottom_address) { 717 size_t fill_size = pointer_delta(start_address, bottom_address); 718 G1CollectedHeap::fill_with_objects(bottom_address, fill_size); 719 increase_used(fill_size * HeapWordSize); 720 } 721 } 722 } 723 724 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) { 725 assert_heap_not_locked_and_not_at_safepoint(); 726 assert(!is_humongous(word_size), "attempt_allocation() should not " 727 "be called for humongous allocation requests"); 728 729 HeapWord* result = _allocator->attempt_allocation(word_size); 730 731 if (result == NULL) { 732 result = attempt_allocation_slow(word_size); 733 } 734 assert_heap_not_locked(); 735 if (result != NULL) { 736 dirty_young_block(result, word_size); 737 } 738 return result; 739 } 740 741 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) { 742 assert(!is_init_completed(), "Expect to be called at JVM init time"); 743 assert(ranges != NULL, "MemRegion array NULL"); 744 assert(count != 0, "No MemRegions provided"); 745 MemRegion reserved = _hrm.reserved(); 746 HeapWord* prev_last_addr = NULL; 747 HeapRegion* prev_last_region = NULL; 748 size_t size_used = 0; 749 size_t uncommitted_regions = 0; 750 751 // For each Memregion, free the G1 regions that constitute it, and 752 // notify mark-sweep that the range is no longer to be considered 'archive.' 753 MutexLockerEx x(Heap_lock); 754 for (size_t i = 0; i < count; i++) { 755 HeapWord* start_address = ranges[i].start(); 756 HeapWord* last_address = ranges[i].last(); 757 758 assert(reserved.contains(start_address) && reserved.contains(last_address), 759 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]", 760 p2i(start_address), p2i(last_address)); 761 assert(start_address > prev_last_addr, 762 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT , 763 p2i(start_address), p2i(prev_last_addr)); 764 size_used += ranges[i].byte_size(); 765 prev_last_addr = last_address; 766 767 HeapRegion* start_region = _hrm.addr_to_region(start_address); 768 HeapRegion* last_region = _hrm.addr_to_region(last_address); 769 770 // Check for ranges that start in the same G1 region in which the previous 771 // range ended, and adjust the start address so we don't try to free 772 // the same region again. If the current range is entirely within that 773 // region, skip it. 774 if (start_region == prev_last_region) { 775 start_address = start_region->end(); 776 if (start_address > last_address) { 777 continue; 778 } 779 start_region = _hrm.addr_to_region(start_address); 780 } 781 prev_last_region = last_region; 782 783 // After verifying that each region was marked as an archive region by 784 // alloc_archive_regions, set it free and empty and uncommit it. 785 HeapRegion* curr_region = start_region; 786 while (curr_region != NULL) { 787 guarantee(curr_region->is_archive(), 788 "Expected archive region at index %u", curr_region->hrm_index()); 789 uint curr_index = curr_region->hrm_index(); 790 _old_set.remove(curr_region); 791 curr_region->set_free(); 792 curr_region->set_top(curr_region->bottom()); 793 if (curr_region != last_region) { 794 curr_region = _hrm.next_region_in_heap(curr_region); 795 } else { 796 curr_region = NULL; 797 } 798 _hrm.shrink_at(curr_index, 1); 799 uncommitted_regions++; 800 } 801 802 // Notify mark-sweep that this is no longer an archive range. 803 G1ArchiveAllocator::set_range_archive(ranges[i], false); 804 } 805 806 if (uncommitted_regions != 0) { 807 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B", 808 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions); 809 } 810 decrease_used(size_used); 811 } 812 813 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) { 814 ResourceMark rm; // For retrieving the thread names in log messages. 815 816 // The structure of this method has a lot of similarities to 817 // attempt_allocation_slow(). The reason these two were not merged 818 // into a single one is that such a method would require several "if 819 // allocation is not humongous do this, otherwise do that" 820 // conditional paths which would obscure its flow. In fact, an early 821 // version of this code did use a unified method which was harder to 822 // follow and, as a result, it had subtle bugs that were hard to 823 // track down. So keeping these two methods separate allows each to 824 // be more readable. It will be good to keep these two in sync as 825 // much as possible. 826 827 assert_heap_not_locked_and_not_at_safepoint(); 828 assert(is_humongous(word_size), "attempt_allocation_humongous() " 829 "should only be called for humongous allocations"); 830 831 // Humongous objects can exhaust the heap quickly, so we should check if we 832 // need to start a marking cycle at each humongous object allocation. We do 833 // the check before we do the actual allocation. The reason for doing it 834 // before the allocation is that we avoid having to keep track of the newly 835 // allocated memory while we do a GC. 836 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", 837 word_size)) { 838 collect(GCCause::_g1_humongous_allocation); 839 } 840 841 // We will loop until a) we manage to successfully perform the 842 // allocation or b) we successfully schedule a collection which 843 // fails to perform the allocation. b) is the only case when we'll 844 // return NULL. 845 HeapWord* result = NULL; 846 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) { 847 bool should_try_gc; 848 uint gc_count_before; 849 850 851 { 852 MutexLockerEx x(Heap_lock); 853 854 // Given that humongous objects are not allocated in young 855 // regions, we'll first try to do the allocation without doing a 856 // collection hoping that there's enough space in the heap. 857 result = humongous_obj_allocate(word_size); 858 if (result != NULL) { 859 size_t size_in_regions = humongous_obj_size_in_regions(word_size); 860 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes); 861 return result; 862 } 863 864 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until 865 // the GCLocker initiated GC has been performed and then retry. This includes 866 // the case when the GC Locker is not active but has not been performed. 867 should_try_gc = !GCLocker::needs_gc(); 868 // Read the GC count while still holding the Heap_lock. 869 gc_count_before = total_collections(); 870 } 871 872 if (should_try_gc) { 873 bool succeeded; 874 result = do_collection_pause(word_size, gc_count_before, &succeeded, 875 GCCause::_g1_humongous_allocation); 876 if (result != NULL) { 877 assert(succeeded, "only way to get back a non-NULL result"); 878 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT, 879 Thread::current()->name(), p2i(result)); 880 return result; 881 } 882 883 if (succeeded) { 884 // We successfully scheduled a collection which failed to allocate. No 885 // point in trying to allocate further. We'll just return NULL. 886 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate " 887 SIZE_FORMAT " words", Thread::current()->name(), word_size); 888 return NULL; 889 } 890 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "", 891 Thread::current()->name(), word_size); 892 } else { 893 // Failed to schedule a collection. 894 if (gclocker_retry_count > GCLockerRetryAllocationCount) { 895 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating " 896 SIZE_FORMAT " words", Thread::current()->name(), word_size); 897 return NULL; 898 } 899 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name()); 900 // The GCLocker is either active or the GCLocker initiated 901 // GC has not yet been performed. Stall until it is and 902 // then retry the allocation. 903 GCLocker::stall_until_clear(); 904 gclocker_retry_count += 1; 905 } 906 907 908 // We can reach here if we were unsuccessful in scheduling a 909 // collection (because another thread beat us to it) or if we were 910 // stalled due to the GC locker. In either can we should retry the 911 // allocation attempt in case another thread successfully 912 // performed a collection and reclaimed enough space. 913 // Humongous object allocation always needs a lock, so we wait for the retry 914 // in the next iteration of the loop, unlike for the regular iteration case. 915 // Give a warning if we seem to be looping forever. 916 917 if ((QueuedAllocationWarningCount > 0) && 918 (try_count % QueuedAllocationWarningCount == 0)) { 919 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words", 920 Thread::current()->name(), try_count, word_size); 921 } 922 } 923 924 ShouldNotReachHere(); 925 return NULL; 926 } 927 928 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size, 929 bool expect_null_mutator_alloc_region) { 930 assert_at_safepoint_on_vm_thread(); 931 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region, 932 "the current alloc region was unexpectedly found to be non-NULL"); 933 934 if (!is_humongous(word_size)) { 935 return _allocator->attempt_allocation_locked(word_size); 936 } else { 937 HeapWord* result = humongous_obj_allocate(word_size); 938 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) { 939 collector_state()->set_initiate_conc_mark_if_possible(true); 940 } 941 return result; 942 } 943 944 ShouldNotReachHere(); 945 } 946 947 class PostCompactionPrinterClosure: public HeapRegionClosure { 948 private: 949 G1HRPrinter* _hr_printer; 950 public: 951 bool do_heap_region(HeapRegion* hr) { 952 assert(!hr->is_young(), "not expecting to find young regions"); 953 _hr_printer->post_compaction(hr); 954 return false; 955 } 956 957 PostCompactionPrinterClosure(G1HRPrinter* hr_printer) 958 : _hr_printer(hr_printer) { } 959 }; 960 961 void G1CollectedHeap::print_hrm_post_compaction() { 962 if (_hr_printer.is_active()) { 963 PostCompactionPrinterClosure cl(hr_printer()); 964 heap_region_iterate(&cl); 965 } 966 } 967 968 void G1CollectedHeap::abort_concurrent_cycle() { 969 // If we start the compaction before the CM threads finish 970 // scanning the root regions we might trip them over as we'll 971 // be moving objects / updating references. So let's wait until 972 // they are done. By telling them to abort, they should complete 973 // early. 974 _cm->root_regions()->abort(); 975 _cm->root_regions()->wait_until_scan_finished(); 976 977 // Disable discovery and empty the discovered lists 978 // for the CM ref processor. 979 _ref_processor_cm->disable_discovery(); 980 _ref_processor_cm->abandon_partial_discovery(); 981 _ref_processor_cm->verify_no_references_recorded(); 982 983 // Abandon current iterations of concurrent marking and concurrent 984 // refinement, if any are in progress. 985 concurrent_mark()->concurrent_cycle_abort(); 986 } 987 988 void G1CollectedHeap::prepare_heap_for_full_collection() { 989 // Make sure we'll choose a new allocation region afterwards. 990 _allocator->release_mutator_alloc_region(); 991 _allocator->abandon_gc_alloc_regions(); 992 g1_rem_set()->cleanupHRRS(); 993 994 // We may have added regions to the current incremental collection 995 // set between the last GC or pause and now. We need to clear the 996 // incremental collection set and then start rebuilding it afresh 997 // after this full GC. 998 abandon_collection_set(collection_set()); 999 1000 tear_down_region_sets(false /* free_list_only */); 1001 } 1002 1003 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) { 1004 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant"); 1005 assert(used() == recalculate_used(), "Should be equal"); 1006 _verifier->verify_region_sets_optional(); 1007 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull); 1008 _verifier->check_bitmaps("Full GC Start"); 1009 } 1010 1011 void G1CollectedHeap::prepare_heap_for_mutators() { 1012 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1013 ClassLoaderDataGraph::purge(); 1014 MetaspaceUtils::verify_metrics(); 1015 1016 // Prepare heap for normal collections. 1017 assert(num_free_regions() == 0, "we should not have added any free regions"); 1018 rebuild_region_sets(false /* free_list_only */); 1019 abort_refinement(); 1020 resize_if_necessary_after_full_collection(); 1021 1022 // Rebuild the strong code root lists for each region 1023 rebuild_strong_code_roots(); 1024 1025 // Start a new incremental collection set for the next pause 1026 start_new_collection_set(); 1027 1028 _allocator->init_mutator_alloc_region(); 1029 1030 // Post collection state updates. 1031 MetaspaceGC::compute_new_size(); 1032 } 1033 1034 void G1CollectedHeap::abort_refinement() { 1035 if (_hot_card_cache->use_cache()) { 1036 _hot_card_cache->reset_hot_cache(); 1037 } 1038 1039 // Discard all remembered set updates. 1040 G1BarrierSet::dirty_card_queue_set().abandon_logs(); 1041 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty"); 1042 } 1043 1044 void G1CollectedHeap::verify_after_full_collection() { 1045 _hrm.verify_optional(); 1046 _verifier->verify_region_sets_optional(); 1047 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull); 1048 // Clear the previous marking bitmap, if needed for bitmap verification. 1049 // Note we cannot do this when we clear the next marking bitmap in 1050 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the 1051 // objects marked during a full GC against the previous bitmap. 1052 // But we need to clear it before calling check_bitmaps below since 1053 // the full GC has compacted objects and updated TAMS but not updated 1054 // the prev bitmap. 1055 if (G1VerifyBitmaps) { 1056 GCTraceTime(Debug, gc)("Clear Bitmap for Verification"); 1057 _cm->clear_prev_bitmap(workers()); 1058 } 1059 _verifier->check_bitmaps("Full GC End"); 1060 1061 // At this point there should be no regions in the 1062 // entire heap tagged as young. 1063 assert(check_young_list_empty(), "young list should be empty at this point"); 1064 1065 // Note: since we've just done a full GC, concurrent 1066 // marking is no longer active. Therefore we need not 1067 // re-enable reference discovery for the CM ref processor. 1068 // That will be done at the start of the next marking cycle. 1069 // We also know that the STW processor should no longer 1070 // discover any new references. 1071 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 1072 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition"); 1073 _ref_processor_stw->verify_no_references_recorded(); 1074 _ref_processor_cm->verify_no_references_recorded(); 1075 } 1076 1077 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) { 1078 // Post collection logging. 1079 // We should do this after we potentially resize the heap so 1080 // that all the COMMIT / UNCOMMIT events are generated before 1081 // the compaction events. 1082 print_hrm_post_compaction(); 1083 heap_transition->print(); 1084 print_heap_after_gc(); 1085 print_heap_regions(); 1086 #ifdef TRACESPINNING 1087 ParallelTaskTerminator::print_termination_counts(); 1088 #endif 1089 } 1090 1091 bool G1CollectedHeap::do_full_collection(bool explicit_gc, 1092 bool clear_all_soft_refs) { 1093 assert_at_safepoint_on_vm_thread(); 1094 1095 if (GCLocker::check_active_before_gc()) { 1096 // Full GC was not completed. 1097 return false; 1098 } 1099 1100 const bool do_clear_all_soft_refs = clear_all_soft_refs || 1101 soft_ref_policy()->should_clear_all_soft_refs(); 1102 1103 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs); 1104 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true); 1105 1106 collector.prepare_collection(); 1107 collector.collect(); 1108 collector.complete_collection(); 1109 1110 // Full collection was successfully completed. 1111 return true; 1112 } 1113 1114 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) { 1115 // Currently, there is no facility in the do_full_collection(bool) API to notify 1116 // the caller that the collection did not succeed (e.g., because it was locked 1117 // out by the GC locker). So, right now, we'll ignore the return value. 1118 bool dummy = do_full_collection(true, /* explicit_gc */ 1119 clear_all_soft_refs); 1120 } 1121 1122 void G1CollectedHeap::resize_if_necessary_after_full_collection() { 1123 // Capacity, free and used after the GC counted as full regions to 1124 // include the waste in the following calculations. 1125 const size_t capacity_after_gc = capacity(); 1126 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes(); 1127 1128 // This is enforced in arguments.cpp. 1129 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, 1130 "otherwise the code below doesn't make sense"); 1131 1132 // We don't have floating point command-line arguments 1133 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; 1134 const double maximum_used_percentage = 1.0 - minimum_free_percentage; 1135 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; 1136 const double minimum_used_percentage = 1.0 - maximum_free_percentage; 1137 1138 const size_t min_heap_size = collector_policy()->min_heap_byte_size(); 1139 const size_t max_heap_size = collector_policy()->max_heap_byte_size(); 1140 1141 // We have to be careful here as these two calculations can overflow 1142 // 32-bit size_t's. 1143 double used_after_gc_d = (double) used_after_gc; 1144 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; 1145 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; 1146 1147 // Let's make sure that they are both under the max heap size, which 1148 // by default will make them fit into a size_t. 1149 double desired_capacity_upper_bound = (double) max_heap_size; 1150 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, 1151 desired_capacity_upper_bound); 1152 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, 1153 desired_capacity_upper_bound); 1154 1155 // We can now safely turn them into size_t's. 1156 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; 1157 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; 1158 1159 // This assert only makes sense here, before we adjust them 1160 // with respect to the min and max heap size. 1161 assert(minimum_desired_capacity <= maximum_desired_capacity, 1162 "minimum_desired_capacity = " SIZE_FORMAT ", " 1163 "maximum_desired_capacity = " SIZE_FORMAT, 1164 minimum_desired_capacity, maximum_desired_capacity); 1165 1166 // Should not be greater than the heap max size. No need to adjust 1167 // it with respect to the heap min size as it's a lower bound (i.e., 1168 // we'll try to make the capacity larger than it, not smaller). 1169 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); 1170 // Should not be less than the heap min size. No need to adjust it 1171 // with respect to the heap max size as it's an upper bound (i.e., 1172 // we'll try to make the capacity smaller than it, not greater). 1173 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); 1174 1175 if (capacity_after_gc < minimum_desired_capacity) { 1176 // Don't expand unless it's significant 1177 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; 1178 1179 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). " 1180 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1181 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1182 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio); 1183 1184 expand(expand_bytes, _workers); 1185 1186 // No expansion, now see if we want to shrink 1187 } else if (capacity_after_gc > maximum_desired_capacity) { 1188 // Capacity too large, compute shrinking size 1189 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; 1190 1191 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). " 1192 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B " 1193 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)", 1194 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio); 1195 1196 shrink(shrink_bytes); 1197 } 1198 } 1199 1200 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size, 1201 bool do_gc, 1202 bool clear_all_soft_refs, 1203 bool expect_null_mutator_alloc_region, 1204 bool* gc_succeeded) { 1205 *gc_succeeded = true; 1206 // Let's attempt the allocation first. 1207 HeapWord* result = 1208 attempt_allocation_at_safepoint(word_size, 1209 expect_null_mutator_alloc_region); 1210 if (result != NULL) { 1211 return result; 1212 } 1213 1214 // In a G1 heap, we're supposed to keep allocation from failing by 1215 // incremental pauses. Therefore, at least for now, we'll favor 1216 // expansion over collection. (This might change in the future if we can 1217 // do something smarter than full collection to satisfy a failed alloc.) 1218 result = expand_and_allocate(word_size); 1219 if (result != NULL) { 1220 return result; 1221 } 1222 1223 if (do_gc) { 1224 // Expansion didn't work, we'll try to do a Full GC. 1225 *gc_succeeded = do_full_collection(false, /* explicit_gc */ 1226 clear_all_soft_refs); 1227 } 1228 1229 return NULL; 1230 } 1231 1232 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size, 1233 bool* succeeded) { 1234 assert_at_safepoint_on_vm_thread(); 1235 1236 // Attempts to allocate followed by Full GC. 1237 HeapWord* result = 1238 satisfy_failed_allocation_helper(word_size, 1239 true, /* do_gc */ 1240 false, /* clear_all_soft_refs */ 1241 false, /* expect_null_mutator_alloc_region */ 1242 succeeded); 1243 1244 if (result != NULL || !*succeeded) { 1245 return result; 1246 } 1247 1248 // Attempts to allocate followed by Full GC that will collect all soft references. 1249 result = satisfy_failed_allocation_helper(word_size, 1250 true, /* do_gc */ 1251 true, /* clear_all_soft_refs */ 1252 true, /* expect_null_mutator_alloc_region */ 1253 succeeded); 1254 1255 if (result != NULL || !*succeeded) { 1256 return result; 1257 } 1258 1259 // Attempts to allocate, no GC 1260 result = satisfy_failed_allocation_helper(word_size, 1261 false, /* do_gc */ 1262 false, /* clear_all_soft_refs */ 1263 true, /* expect_null_mutator_alloc_region */ 1264 succeeded); 1265 1266 if (result != NULL) { 1267 return result; 1268 } 1269 1270 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 1271 "Flag should have been handled and cleared prior to this point"); 1272 1273 // What else? We might try synchronous finalization later. If the total 1274 // space available is large enough for the allocation, then a more 1275 // complete compaction phase than we've tried so far might be 1276 // appropriate. 1277 return NULL; 1278 } 1279 1280 // Attempting to expand the heap sufficiently 1281 // to support an allocation of the given "word_size". If 1282 // successful, perform the allocation and return the address of the 1283 // allocated block, or else "NULL". 1284 1285 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) { 1286 assert_at_safepoint_on_vm_thread(); 1287 1288 _verifier->verify_region_sets_optional(); 1289 1290 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes); 1291 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B", 1292 word_size * HeapWordSize); 1293 1294 1295 if (expand(expand_bytes, _workers)) { 1296 _hrm.verify_optional(); 1297 _verifier->verify_region_sets_optional(); 1298 return attempt_allocation_at_safepoint(word_size, 1299 false /* expect_null_mutator_alloc_region */); 1300 } 1301 return NULL; 1302 } 1303 1304 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) { 1305 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); 1306 aligned_expand_bytes = align_up(aligned_expand_bytes, 1307 HeapRegion::GrainBytes); 1308 1309 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B", 1310 expand_bytes, aligned_expand_bytes); 1311 1312 if (is_maximal_no_gc()) { 1313 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)"); 1314 return false; 1315 } 1316 1317 double expand_heap_start_time_sec = os::elapsedTime(); 1318 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes); 1319 assert(regions_to_expand > 0, "Must expand by at least one region"); 1320 1321 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers); 1322 if (expand_time_ms != NULL) { 1323 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS; 1324 } 1325 1326 if (expanded_by > 0) { 1327 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes; 1328 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition"); 1329 g1_policy()->record_new_heap_size(num_regions()); 1330 } else { 1331 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)"); 1332 1333 // The expansion of the virtual storage space was unsuccessful. 1334 // Let's see if it was because we ran out of swap. 1335 if (G1ExitOnExpansionFailure && 1336 _hrm.available() >= regions_to_expand) { 1337 // We had head room... 1338 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion"); 1339 } 1340 } 1341 return regions_to_expand > 0; 1342 } 1343 1344 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) { 1345 size_t aligned_shrink_bytes = 1346 ReservedSpace::page_align_size_down(shrink_bytes); 1347 aligned_shrink_bytes = align_down(aligned_shrink_bytes, 1348 HeapRegion::GrainBytes); 1349 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes); 1350 1351 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove); 1352 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes; 1353 1354 1355 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", 1356 shrink_bytes, aligned_shrink_bytes, shrunk_bytes); 1357 if (num_regions_removed > 0) { 1358 g1_policy()->record_new_heap_size(num_regions()); 1359 } else { 1360 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)"); 1361 } 1362 } 1363 1364 void G1CollectedHeap::shrink(size_t shrink_bytes) { 1365 _verifier->verify_region_sets_optional(); 1366 1367 // We should only reach here at the end of a Full GC which means we 1368 // should not not be holding to any GC alloc regions. The method 1369 // below will make sure of that and do any remaining clean up. 1370 _allocator->abandon_gc_alloc_regions(); 1371 1372 // Instead of tearing down / rebuilding the free lists here, we 1373 // could instead use the remove_all_pending() method on free_list to 1374 // remove only the ones that we need to remove. 1375 tear_down_region_sets(true /* free_list_only */); 1376 shrink_helper(shrink_bytes); 1377 rebuild_region_sets(true /* free_list_only */); 1378 1379 _hrm.verify_optional(); 1380 _verifier->verify_region_sets_optional(); 1381 } 1382 1383 // Public methods. 1384 1385 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) : 1386 CollectedHeap(), 1387 _young_gen_sampling_thread(NULL), 1388 _collector_policy(collector_policy), 1389 _soft_ref_policy(), 1390 _card_table(NULL), 1391 _memory_manager("G1 Young Generation", "end of minor GC"), 1392 _full_gc_memory_manager("G1 Old Generation", "end of major GC"), 1393 _eden_pool(NULL), 1394 _survivor_pool(NULL), 1395 _old_pool(NULL), 1396 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()), 1397 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()), 1398 _g1_policy(new G1Policy(_gc_timer_stw)), 1399 _collection_set(this, _g1_policy), 1400 _dirty_card_queue_set(false), 1401 _ref_processor_stw(NULL), 1402 _is_alive_closure_stw(this), 1403 _is_subject_to_discovery_stw(this), 1404 _ref_processor_cm(NULL), 1405 _is_alive_closure_cm(this), 1406 _is_subject_to_discovery_cm(this), 1407 _bot(NULL), 1408 _hot_card_cache(NULL), 1409 _g1_rem_set(NULL), 1410 _cr(NULL), 1411 _g1mm(NULL), 1412 _preserved_marks_set(true /* in_c_heap */), 1413 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()), 1414 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()), 1415 _humongous_reclaim_candidates(), 1416 _has_humongous_reclaim_candidates(false), 1417 _archive_allocator(NULL), 1418 _summary_bytes_used(0), 1419 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight), 1420 _old_evac_stats("Old", OldPLABSize, PLABWeight), 1421 _expand_heap_after_alloc_failure(true), 1422 _old_marking_cycles_started(0), 1423 _old_marking_cycles_completed(0), 1424 _in_cset_fast_test() { 1425 1426 _workers = new WorkGang("GC Thread", ParallelGCThreads, 1427 /* are_GC_task_threads */true, 1428 /* are_ConcurrentGC_threads */false); 1429 _workers->initialize_workers(); 1430 _verifier = new G1HeapVerifier(this); 1431 1432 _allocator = new G1Allocator(this); 1433 1434 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics()); 1435 1436 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords); 1437 1438 // Override the default _filler_array_max_size so that no humongous filler 1439 // objects are created. 1440 _filler_array_max_size = _humongous_object_threshold_in_words; 1441 1442 uint n_queues = ParallelGCThreads; 1443 _task_queues = new RefToScanQueueSet(n_queues); 1444 1445 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC); 1446 1447 for (uint i = 0; i < n_queues; i++) { 1448 RefToScanQueue* q = new RefToScanQueue(); 1449 q->initialize(); 1450 _task_queues->register_queue(i, q); 1451 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo(); 1452 } 1453 1454 // Initialize the G1EvacuationFailureALot counters and flags. 1455 NOT_PRODUCT(reset_evacuation_should_fail();) 1456 1457 guarantee(_task_queues != NULL, "task_queues allocation failure."); 1458 } 1459 1460 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description, 1461 size_t size, 1462 size_t translation_factor) { 1463 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1); 1464 // Allocate a new reserved space, preferring to use large pages. 1465 ReservedSpace rs(size, preferred_page_size); 1466 G1RegionToSpaceMapper* result = 1467 G1RegionToSpaceMapper::create_mapper(rs, 1468 size, 1469 rs.alignment(), 1470 HeapRegion::GrainBytes, 1471 translation_factor, 1472 mtGC); 1473 1474 os::trace_page_sizes_for_requested_size(description, 1475 size, 1476 preferred_page_size, 1477 rs.alignment(), 1478 rs.base(), 1479 rs.size()); 1480 1481 return result; 1482 } 1483 1484 jint G1CollectedHeap::initialize_concurrent_refinement() { 1485 jint ecode = JNI_OK; 1486 _cr = G1ConcurrentRefine::create(&ecode); 1487 return ecode; 1488 } 1489 1490 jint G1CollectedHeap::initialize_young_gen_sampling_thread() { 1491 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread(); 1492 if (_young_gen_sampling_thread->osthread() == NULL) { 1493 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread"); 1494 return JNI_ENOMEM; 1495 } 1496 return JNI_OK; 1497 } 1498 1499 jint G1CollectedHeap::initialize() { 1500 os::enable_vtime(); 1501 1502 // Necessary to satisfy locking discipline assertions. 1503 1504 MutexLocker x(Heap_lock); 1505 1506 // While there are no constraints in the GC code that HeapWordSize 1507 // be any particular value, there are multiple other areas in the 1508 // system which believe this to be true (e.g. oop->object_size in some 1509 // cases incorrectly returns the size in wordSize units rather than 1510 // HeapWordSize). 1511 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 1512 1513 size_t init_byte_size = collector_policy()->initial_heap_byte_size(); 1514 size_t max_byte_size = collector_policy()->max_heap_byte_size(); 1515 size_t heap_alignment = collector_policy()->heap_alignment(); 1516 1517 // Ensure that the sizes are properly aligned. 1518 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1519 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap"); 1520 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap"); 1521 1522 // Reserve the maximum. 1523 1524 // When compressed oops are enabled, the preferred heap base 1525 // is calculated by subtracting the requested size from the 1526 // 32Gb boundary and using the result as the base address for 1527 // heap reservation. If the requested size is not aligned to 1528 // HeapRegion::GrainBytes (i.e. the alignment that is passed 1529 // into the ReservedHeapSpace constructor) then the actual 1530 // base of the reserved heap may end up differing from the 1531 // address that was requested (i.e. the preferred heap base). 1532 // If this happens then we could end up using a non-optimal 1533 // compressed oops mode. 1534 1535 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, 1536 heap_alignment); 1537 1538 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 1539 1540 // Create the barrier set for the entire reserved region. 1541 G1CardTable* ct = new G1CardTable(reserved_region()); 1542 ct->initialize(); 1543 G1BarrierSet* bs = new G1BarrierSet(ct); 1544 bs->initialize(); 1545 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity"); 1546 BarrierSet::set_barrier_set(bs); 1547 _card_table = ct; 1548 1549 // Create the hot card cache. 1550 _hot_card_cache = new G1HotCardCache(this); 1551 1552 // Carve out the G1 part of the heap. 1553 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size); 1554 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 1555 G1RegionToSpaceMapper* heap_storage = 1556 G1RegionToSpaceMapper::create_mapper(g1_rs, 1557 g1_rs.size(), 1558 page_size, 1559 HeapRegion::GrainBytes, 1560 1, 1561 mtJavaHeap); 1562 os::trace_page_sizes("Heap", 1563 collector_policy()->min_heap_byte_size(), 1564 max_byte_size, 1565 page_size, 1566 heap_rs.base(), 1567 heap_rs.size()); 1568 heap_storage->set_mapping_changed_listener(&_listener); 1569 1570 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps. 1571 G1RegionToSpaceMapper* bot_storage = 1572 create_aux_memory_mapper("Block Offset Table", 1573 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize), 1574 G1BlockOffsetTable::heap_map_factor()); 1575 1576 G1RegionToSpaceMapper* cardtable_storage = 1577 create_aux_memory_mapper("Card Table", 1578 G1CardTable::compute_size(g1_rs.size() / HeapWordSize), 1579 G1CardTable::heap_map_factor()); 1580 1581 G1RegionToSpaceMapper* card_counts_storage = 1582 create_aux_memory_mapper("Card Counts Table", 1583 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize), 1584 G1CardCounts::heap_map_factor()); 1585 1586 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size()); 1587 G1RegionToSpaceMapper* prev_bitmap_storage = 1588 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1589 G1RegionToSpaceMapper* next_bitmap_storage = 1590 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor()); 1591 1592 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage); 1593 _card_table->initialize(cardtable_storage); 1594 // Do later initialization work for concurrent refinement. 1595 _hot_card_cache->initialize(card_counts_storage); 1596 1597 // 6843694 - ensure that the maximum region index can fit 1598 // in the remembered set structures. 1599 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1; 1600 guarantee((max_regions() - 1) <= max_region_idx, "too many regions"); 1601 1602 // Also create a G1 rem set. 1603 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache); 1604 _g1_rem_set->initialize(max_capacity(), max_regions()); 1605 1606 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1; 1607 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized"); 1608 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region, 1609 "too many cards per region"); 1610 1611 FreeRegionList::set_unrealistically_long_length(max_regions() + 1); 1612 1613 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage); 1614 1615 { 1616 HeapWord* start = _hrm.reserved().start(); 1617 HeapWord* end = _hrm.reserved().end(); 1618 size_t granularity = HeapRegion::GrainBytes; 1619 1620 _in_cset_fast_test.initialize(start, end, granularity); 1621 _humongous_reclaim_candidates.initialize(start, end, granularity); 1622 } 1623 1624 // Create the G1ConcurrentMark data structure and thread. 1625 // (Must do this late, so that "max_regions" is defined.) 1626 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage); 1627 if (_cm == NULL || !_cm->completed_initialization()) { 1628 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark"); 1629 return JNI_ENOMEM; 1630 } 1631 _cm_thread = _cm->cm_thread(); 1632 1633 // Now expand into the initial heap size. 1634 if (!expand(init_byte_size, _workers)) { 1635 vm_shutdown_during_initialization("Failed to allocate initial heap."); 1636 return JNI_ENOMEM; 1637 } 1638 1639 // Perform any initialization actions delegated to the policy. 1640 g1_policy()->init(this, &_collection_set); 1641 1642 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon, 1643 SATB_Q_FL_lock, 1644 G1SATBProcessCompletedThreshold, 1645 Shared_SATB_Q_lock); 1646 1647 jint ecode = initialize_concurrent_refinement(); 1648 if (ecode != JNI_OK) { 1649 return ecode; 1650 } 1651 1652 ecode = initialize_young_gen_sampling_thread(); 1653 if (ecode != JNI_OK) { 1654 return ecode; 1655 } 1656 1657 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1658 DirtyCardQ_FL_lock, 1659 (int)concurrent_refine()->yellow_zone(), 1660 (int)concurrent_refine()->red_zone(), 1661 Shared_DirtyCardQ_lock, 1662 NULL, // fl_owner 1663 true); // init_free_ids 1664 1665 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon, 1666 DirtyCardQ_FL_lock, 1667 -1, // never trigger processing 1668 -1, // no limit on length 1669 Shared_DirtyCardQ_lock, 1670 &G1BarrierSet::dirty_card_queue_set()); 1671 1672 // Here we allocate the dummy HeapRegion that is required by the 1673 // G1AllocRegion class. 1674 HeapRegion* dummy_region = _hrm.get_dummy_region(); 1675 1676 // We'll re-use the same region whether the alloc region will 1677 // require BOT updates or not and, if it doesn't, then a non-young 1678 // region will complain that it cannot support allocations without 1679 // BOT updates. So we'll tag the dummy region as eden to avoid that. 1680 dummy_region->set_eden(); 1681 // Make sure it's full. 1682 dummy_region->set_top(dummy_region->end()); 1683 G1AllocRegion::setup(this, dummy_region); 1684 1685 _allocator->init_mutator_alloc_region(); 1686 1687 // Do create of the monitoring and management support so that 1688 // values in the heap have been properly initialized. 1689 _g1mm = new G1MonitoringSupport(this); 1690 1691 G1StringDedup::initialize(); 1692 1693 _preserved_marks_set.init(ParallelGCThreads); 1694 1695 _collection_set.initialize(max_regions()); 1696 1697 return JNI_OK; 1698 } 1699 1700 void G1CollectedHeap::initialize_serviceability() { 1701 _eden_pool = new G1EdenPool(this); 1702 _survivor_pool = new G1SurvivorPool(this); 1703 _old_pool = new G1OldGenPool(this); 1704 1705 _full_gc_memory_manager.add_pool(_eden_pool); 1706 _full_gc_memory_manager.add_pool(_survivor_pool); 1707 _full_gc_memory_manager.add_pool(_old_pool); 1708 1709 _memory_manager.add_pool(_eden_pool); 1710 _memory_manager.add_pool(_survivor_pool); 1711 1712 } 1713 1714 void G1CollectedHeap::stop() { 1715 // Stop all concurrent threads. We do this to make sure these threads 1716 // do not continue to execute and access resources (e.g. logging) 1717 // that are destroyed during shutdown. 1718 _cr->stop(); 1719 _young_gen_sampling_thread->stop(); 1720 _cm_thread->stop(); 1721 if (G1StringDedup::is_enabled()) { 1722 G1StringDedup::stop(); 1723 } 1724 } 1725 1726 void G1CollectedHeap::safepoint_synchronize_begin() { 1727 SuspendibleThreadSet::synchronize(); 1728 } 1729 1730 void G1CollectedHeap::safepoint_synchronize_end() { 1731 SuspendibleThreadSet::desynchronize(); 1732 } 1733 1734 size_t G1CollectedHeap::conservative_max_heap_alignment() { 1735 return HeapRegion::max_region_size(); 1736 } 1737 1738 void G1CollectedHeap::post_initialize() { 1739 CollectedHeap::post_initialize(); 1740 ref_processing_init(); 1741 } 1742 1743 void G1CollectedHeap::ref_processing_init() { 1744 // Reference processing in G1 currently works as follows: 1745 // 1746 // * There are two reference processor instances. One is 1747 // used to record and process discovered references 1748 // during concurrent marking; the other is used to 1749 // record and process references during STW pauses 1750 // (both full and incremental). 1751 // * Both ref processors need to 'span' the entire heap as 1752 // the regions in the collection set may be dotted around. 1753 // 1754 // * For the concurrent marking ref processor: 1755 // * Reference discovery is enabled at initial marking. 1756 // * Reference discovery is disabled and the discovered 1757 // references processed etc during remarking. 1758 // * Reference discovery is MT (see below). 1759 // * Reference discovery requires a barrier (see below). 1760 // * Reference processing may or may not be MT 1761 // (depending on the value of ParallelRefProcEnabled 1762 // and ParallelGCThreads). 1763 // * A full GC disables reference discovery by the CM 1764 // ref processor and abandons any entries on it's 1765 // discovered lists. 1766 // 1767 // * For the STW processor: 1768 // * Non MT discovery is enabled at the start of a full GC. 1769 // * Processing and enqueueing during a full GC is non-MT. 1770 // * During a full GC, references are processed after marking. 1771 // 1772 // * Discovery (may or may not be MT) is enabled at the start 1773 // of an incremental evacuation pause. 1774 // * References are processed near the end of a STW evacuation pause. 1775 // * For both types of GC: 1776 // * Discovery is atomic - i.e. not concurrent. 1777 // * Reference discovery will not need a barrier. 1778 1779 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1); 1780 1781 // Concurrent Mark ref processor 1782 _ref_processor_cm = 1783 new ReferenceProcessor(&_is_subject_to_discovery_cm, 1784 mt_processing, // mt processing 1785 ParallelGCThreads, // degree of mt processing 1786 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery 1787 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery 1788 false, // Reference discovery is not atomic 1789 &_is_alive_closure_cm); // is alive closure 1790 1791 // STW ref processor 1792 _ref_processor_stw = 1793 new ReferenceProcessor(&_is_subject_to_discovery_stw, 1794 mt_processing, // mt processing 1795 ParallelGCThreads, // degree of mt processing 1796 (ParallelGCThreads > 1), // mt discovery 1797 ParallelGCThreads, // degree of mt discovery 1798 true, // Reference discovery is atomic 1799 &_is_alive_closure_stw); // is alive closure 1800 } 1801 1802 CollectorPolicy* G1CollectedHeap::collector_policy() const { 1803 return _collector_policy; 1804 } 1805 1806 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() { 1807 return &_soft_ref_policy; 1808 } 1809 1810 size_t G1CollectedHeap::capacity() const { 1811 return _hrm.length() * HeapRegion::GrainBytes; 1812 } 1813 1814 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const { 1815 return _hrm.total_free_bytes(); 1816 } 1817 1818 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) { 1819 _hot_card_cache->drain(cl, worker_i); 1820 } 1821 1822 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) { 1823 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 1824 size_t n_completed_buffers = 0; 1825 while (dcqs.apply_closure_during_gc(cl, worker_i)) { 1826 n_completed_buffers++; 1827 } 1828 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers); 1829 dcqs.clear_n_completed_buffers(); 1830 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!"); 1831 } 1832 1833 // Computes the sum of the storage used by the various regions. 1834 size_t G1CollectedHeap::used() const { 1835 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions(); 1836 if (_archive_allocator != NULL) { 1837 result += _archive_allocator->used(); 1838 } 1839 return result; 1840 } 1841 1842 size_t G1CollectedHeap::used_unlocked() const { 1843 return _summary_bytes_used; 1844 } 1845 1846 class SumUsedClosure: public HeapRegionClosure { 1847 size_t _used; 1848 public: 1849 SumUsedClosure() : _used(0) {} 1850 bool do_heap_region(HeapRegion* r) { 1851 _used += r->used(); 1852 return false; 1853 } 1854 size_t result() { return _used; } 1855 }; 1856 1857 size_t G1CollectedHeap::recalculate_used() const { 1858 double recalculate_used_start = os::elapsedTime(); 1859 1860 SumUsedClosure blk; 1861 heap_region_iterate(&blk); 1862 1863 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0); 1864 return blk.result(); 1865 } 1866 1867 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) { 1868 switch (cause) { 1869 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent; 1870 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 1871 case GCCause::_wb_conc_mark: return true; 1872 default : return false; 1873 } 1874 } 1875 1876 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 1877 switch (cause) { 1878 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 1879 case GCCause::_g1_humongous_allocation: return true; 1880 default: return is_user_requested_concurrent_full_gc(cause); 1881 } 1882 } 1883 1884 #ifndef PRODUCT 1885 void G1CollectedHeap::allocate_dummy_regions() { 1886 // Let's fill up most of the region 1887 size_t word_size = HeapRegion::GrainWords - 1024; 1888 // And as a result the region we'll allocate will be humongous. 1889 guarantee(is_humongous(word_size), "sanity"); 1890 1891 // _filler_array_max_size is set to humongous object threshold 1892 // but temporarily change it to use CollectedHeap::fill_with_object(). 1893 SizeTFlagSetting fs(_filler_array_max_size, word_size); 1894 1895 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) { 1896 // Let's use the existing mechanism for the allocation 1897 HeapWord* dummy_obj = humongous_obj_allocate(word_size); 1898 if (dummy_obj != NULL) { 1899 MemRegion mr(dummy_obj, word_size); 1900 CollectedHeap::fill_with_object(mr); 1901 } else { 1902 // If we can't allocate once, we probably cannot allocate 1903 // again. Let's get out of the loop. 1904 break; 1905 } 1906 } 1907 } 1908 #endif // !PRODUCT 1909 1910 void G1CollectedHeap::increment_old_marking_cycles_started() { 1911 assert(_old_marking_cycles_started == _old_marking_cycles_completed || 1912 _old_marking_cycles_started == _old_marking_cycles_completed + 1, 1913 "Wrong marking cycle count (started: %d, completed: %d)", 1914 _old_marking_cycles_started, _old_marking_cycles_completed); 1915 1916 _old_marking_cycles_started++; 1917 } 1918 1919 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { 1920 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 1921 1922 // We assume that if concurrent == true, then the caller is a 1923 // concurrent thread that was joined the Suspendible Thread 1924 // Set. If there's ever a cheap way to check this, we should add an 1925 // assert here. 1926 1927 // Given that this method is called at the end of a Full GC or of a 1928 // concurrent cycle, and those can be nested (i.e., a Full GC can 1929 // interrupt a concurrent cycle), the number of full collections 1930 // completed should be either one (in the case where there was no 1931 // nesting) or two (when a Full GC interrupted a concurrent cycle) 1932 // behind the number of full collections started. 1933 1934 // This is the case for the inner caller, i.e. a Full GC. 1935 assert(concurrent || 1936 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || 1937 (_old_marking_cycles_started == _old_marking_cycles_completed + 2), 1938 "for inner caller (Full GC): _old_marking_cycles_started = %u " 1939 "is inconsistent with _old_marking_cycles_completed = %u", 1940 _old_marking_cycles_started, _old_marking_cycles_completed); 1941 1942 // This is the case for the outer caller, i.e. the concurrent cycle. 1943 assert(!concurrent || 1944 (_old_marking_cycles_started == _old_marking_cycles_completed + 1), 1945 "for outer caller (concurrent cycle): " 1946 "_old_marking_cycles_started = %u " 1947 "is inconsistent with _old_marking_cycles_completed = %u", 1948 _old_marking_cycles_started, _old_marking_cycles_completed); 1949 1950 _old_marking_cycles_completed += 1; 1951 1952 // We need to clear the "in_progress" flag in the CM thread before 1953 // we wake up any waiters (especially when ExplicitInvokesConcurrent 1954 // is set) so that if a waiter requests another System.gc() it doesn't 1955 // incorrectly see that a marking cycle is still in progress. 1956 if (concurrent) { 1957 _cm_thread->set_idle(); 1958 } 1959 1960 // This notify_all() will ensure that a thread that called 1961 // System.gc() with (with ExplicitGCInvokesConcurrent set or not) 1962 // and it's waiting for a full GC to finish will be woken up. It is 1963 // waiting in VM_G1CollectForAllocation::doit_epilogue(). 1964 FullGCCount_lock->notify_all(); 1965 } 1966 1967 void G1CollectedHeap::collect(GCCause::Cause cause) { 1968 assert_heap_not_locked(); 1969 1970 uint gc_count_before; 1971 uint old_marking_count_before; 1972 uint full_gc_count_before; 1973 bool retry_gc; 1974 1975 do { 1976 retry_gc = false; 1977 1978 { 1979 MutexLocker ml(Heap_lock); 1980 1981 // Read the GC count while holding the Heap_lock 1982 gc_count_before = total_collections(); 1983 full_gc_count_before = total_full_collections(); 1984 old_marking_count_before = _old_marking_cycles_started; 1985 } 1986 1987 if (should_do_concurrent_full_gc(cause)) { 1988 // Schedule an initial-mark evacuation pause that will start a 1989 // concurrent cycle. We're setting word_size to 0 which means that 1990 // we are not requesting a post-GC allocation. 1991 VM_G1CollectForAllocation op(0, /* word_size */ 1992 gc_count_before, 1993 cause, 1994 true, /* should_initiate_conc_mark */ 1995 g1_policy()->max_pause_time_ms()); 1996 VMThread::execute(&op); 1997 if (!op.pause_succeeded()) { 1998 if (old_marking_count_before == _old_marking_cycles_started) { 1999 retry_gc = op.should_retry_gc(); 2000 } else { 2001 // A Full GC happened while we were trying to schedule the 2002 // initial-mark GC. No point in starting a new cycle given 2003 // that the whole heap was collected anyway. 2004 } 2005 2006 if (retry_gc) { 2007 if (GCLocker::is_active_and_needs_gc()) { 2008 GCLocker::stall_until_clear(); 2009 } 2010 } 2011 } 2012 } else { 2013 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc 2014 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) { 2015 2016 // Schedule a standard evacuation pause. We're setting word_size 2017 // to 0 which means that we are not requesting a post-GC allocation. 2018 VM_G1CollectForAllocation op(0, /* word_size */ 2019 gc_count_before, 2020 cause, 2021 false, /* should_initiate_conc_mark */ 2022 g1_policy()->max_pause_time_ms()); 2023 VMThread::execute(&op); 2024 } else { 2025 // Schedule a Full GC. 2026 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); 2027 VMThread::execute(&op); 2028 } 2029 } 2030 } while (retry_gc); 2031 } 2032 2033 bool G1CollectedHeap::is_in(const void* p) const { 2034 if (_hrm.reserved().contains(p)) { 2035 // Given that we know that p is in the reserved space, 2036 // heap_region_containing() should successfully 2037 // return the containing region. 2038 HeapRegion* hr = heap_region_containing(p); 2039 return hr->is_in(p); 2040 } else { 2041 return false; 2042 } 2043 } 2044 2045 #ifdef ASSERT 2046 bool G1CollectedHeap::is_in_exact(const void* p) const { 2047 bool contains = reserved_region().contains(p); 2048 bool available = _hrm.is_available(addr_to_region((HeapWord*)p)); 2049 if (contains && available) { 2050 return true; 2051 } else { 2052 return false; 2053 } 2054 } 2055 #endif 2056 2057 // Iteration functions. 2058 2059 // Iterates an ObjectClosure over all objects within a HeapRegion. 2060 2061 class IterateObjectClosureRegionClosure: public HeapRegionClosure { 2062 ObjectClosure* _cl; 2063 public: 2064 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {} 2065 bool do_heap_region(HeapRegion* r) { 2066 if (!r->is_continues_humongous()) { 2067 r->object_iterate(_cl); 2068 } 2069 return false; 2070 } 2071 }; 2072 2073 void G1CollectedHeap::object_iterate(ObjectClosure* cl) { 2074 IterateObjectClosureRegionClosure blk(cl); 2075 heap_region_iterate(&blk); 2076 } 2077 2078 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const { 2079 _hrm.iterate(cl); 2080 } 2081 2082 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 2083 HeapRegionClaimer *hrclaimer, 2084 uint worker_id) const { 2085 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id)); 2086 } 2087 2088 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl, 2089 HeapRegionClaimer *hrclaimer) const { 2090 _hrm.par_iterate(cl, hrclaimer, 0); 2091 } 2092 2093 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) { 2094 _collection_set.iterate(cl); 2095 } 2096 2097 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) { 2098 _collection_set.iterate_from(cl, worker_id, workers()->active_workers()); 2099 } 2100 2101 HeapWord* G1CollectedHeap::block_start(const void* addr) const { 2102 HeapRegion* hr = heap_region_containing(addr); 2103 return hr->block_start(addr); 2104 } 2105 2106 size_t G1CollectedHeap::block_size(const HeapWord* addr) const { 2107 HeapRegion* hr = heap_region_containing(addr); 2108 return hr->block_size(addr); 2109 } 2110 2111 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const { 2112 HeapRegion* hr = heap_region_containing(addr); 2113 return hr->block_is_obj(addr); 2114 } 2115 2116 bool G1CollectedHeap::supports_tlab_allocation() const { 2117 return true; 2118 } 2119 2120 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const { 2121 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes; 2122 } 2123 2124 size_t G1CollectedHeap::tlab_used(Thread* ignored) const { 2125 return _eden.length() * HeapRegion::GrainBytes; 2126 } 2127 2128 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size 2129 // must be equal to the humongous object limit. 2130 size_t G1CollectedHeap::max_tlab_size() const { 2131 return align_down(_humongous_object_threshold_in_words, MinObjAlignment); 2132 } 2133 2134 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const { 2135 return _allocator->unsafe_max_tlab_alloc(); 2136 } 2137 2138 size_t G1CollectedHeap::max_capacity() const { 2139 return _hrm.reserved().byte_size(); 2140 } 2141 2142 jlong G1CollectedHeap::millis_since_last_gc() { 2143 // See the notes in GenCollectedHeap::millis_since_last_gc() 2144 // for more information about the implementation. 2145 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) - 2146 _g1_policy->collection_pause_end_millis(); 2147 if (ret_val < 0) { 2148 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 2149 ". returning zero instead.", ret_val); 2150 return 0; 2151 } 2152 return ret_val; 2153 } 2154 2155 void G1CollectedHeap::prepare_for_verify() { 2156 _verifier->prepare_for_verify(); 2157 } 2158 2159 void G1CollectedHeap::verify(VerifyOption vo) { 2160 _verifier->verify(vo); 2161 } 2162 2163 bool G1CollectedHeap::supports_concurrent_phase_control() const { 2164 return true; 2165 } 2166 2167 const char* const* G1CollectedHeap::concurrent_phases() const { 2168 return _cm_thread->concurrent_phases(); 2169 } 2170 2171 bool G1CollectedHeap::request_concurrent_phase(const char* phase) { 2172 return _cm_thread->request_concurrent_phase(phase); 2173 } 2174 2175 class PrintRegionClosure: public HeapRegionClosure { 2176 outputStream* _st; 2177 public: 2178 PrintRegionClosure(outputStream* st) : _st(st) {} 2179 bool do_heap_region(HeapRegion* r) { 2180 r->print_on(_st); 2181 return false; 2182 } 2183 }; 2184 2185 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2186 const HeapRegion* hr, 2187 const VerifyOption vo) const { 2188 switch (vo) { 2189 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 2190 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 2191 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr); 2192 default: ShouldNotReachHere(); 2193 } 2194 return false; // keep some compilers happy 2195 } 2196 2197 bool G1CollectedHeap::is_obj_dead_cond(const oop obj, 2198 const VerifyOption vo) const { 2199 switch (vo) { 2200 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 2201 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 2202 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj); 2203 default: ShouldNotReachHere(); 2204 } 2205 return false; // keep some compilers happy 2206 } 2207 2208 void G1CollectedHeap::print_heap_regions() const { 2209 LogTarget(Trace, gc, heap, region) lt; 2210 if (lt.is_enabled()) { 2211 LogStream ls(lt); 2212 print_regions_on(&ls); 2213 } 2214 } 2215 2216 void G1CollectedHeap::print_on(outputStream* st) const { 2217 st->print(" %-20s", "garbage-first heap"); 2218 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 2219 capacity()/K, used_unlocked()/K); 2220 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")", 2221 p2i(_hrm.reserved().start()), 2222 p2i(_hrm.reserved().end())); 2223 st->cr(); 2224 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K); 2225 uint young_regions = young_regions_count(); 2226 st->print("%u young (" SIZE_FORMAT "K), ", young_regions, 2227 (size_t) young_regions * HeapRegion::GrainBytes / K); 2228 uint survivor_regions = survivor_regions_count(); 2229 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions, 2230 (size_t) survivor_regions * HeapRegion::GrainBytes / K); 2231 st->cr(); 2232 MetaspaceUtils::print_on(st); 2233 } 2234 2235 void G1CollectedHeap::print_regions_on(outputStream* st) const { 2236 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, " 2237 "HS=humongous(starts), HC=humongous(continues), " 2238 "CS=collection set, F=free, A=archive, " 2239 "TAMS=top-at-mark-start (previous, next)"); 2240 PrintRegionClosure blk(st); 2241 heap_region_iterate(&blk); 2242 } 2243 2244 void G1CollectedHeap::print_extended_on(outputStream* st) const { 2245 print_on(st); 2246 2247 // Print the per-region information. 2248 print_regions_on(st); 2249 } 2250 2251 void G1CollectedHeap::print_on_error(outputStream* st) const { 2252 this->CollectedHeap::print_on_error(st); 2253 2254 if (_cm != NULL) { 2255 st->cr(); 2256 _cm->print_on_error(st); 2257 } 2258 } 2259 2260 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const { 2261 workers()->print_worker_threads_on(st); 2262 _cm_thread->print_on(st); 2263 st->cr(); 2264 _cm->print_worker_threads_on(st); 2265 _cr->print_threads_on(st); 2266 _young_gen_sampling_thread->print_on(st); 2267 if (G1StringDedup::is_enabled()) { 2268 G1StringDedup::print_worker_threads_on(st); 2269 } 2270 } 2271 2272 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const { 2273 workers()->threads_do(tc); 2274 tc->do_thread(_cm_thread); 2275 _cm->threads_do(tc); 2276 _cr->threads_do(tc); 2277 tc->do_thread(_young_gen_sampling_thread); 2278 if (G1StringDedup::is_enabled()) { 2279 G1StringDedup::threads_do(tc); 2280 } 2281 } 2282 2283 void G1CollectedHeap::print_tracing_info() const { 2284 g1_rem_set()->print_summary_info(); 2285 concurrent_mark()->print_summary_info(); 2286 } 2287 2288 #ifndef PRODUCT 2289 // Helpful for debugging RSet issues. 2290 2291 class PrintRSetsClosure : public HeapRegionClosure { 2292 private: 2293 const char* _msg; 2294 size_t _occupied_sum; 2295 2296 public: 2297 bool do_heap_region(HeapRegion* r) { 2298 HeapRegionRemSet* hrrs = r->rem_set(); 2299 size_t occupied = hrrs->occupied(); 2300 _occupied_sum += occupied; 2301 2302 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r)); 2303 if (occupied == 0) { 2304 tty->print_cr(" RSet is empty"); 2305 } else { 2306 hrrs->print(); 2307 } 2308 tty->print_cr("----------"); 2309 return false; 2310 } 2311 2312 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) { 2313 tty->cr(); 2314 tty->print_cr("========================================"); 2315 tty->print_cr("%s", msg); 2316 tty->cr(); 2317 } 2318 2319 ~PrintRSetsClosure() { 2320 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum); 2321 tty->print_cr("========================================"); 2322 tty->cr(); 2323 } 2324 }; 2325 2326 void G1CollectedHeap::print_cset_rsets() { 2327 PrintRSetsClosure cl("Printing CSet RSets"); 2328 collection_set_iterate(&cl); 2329 } 2330 2331 void G1CollectedHeap::print_all_rsets() { 2332 PrintRSetsClosure cl("Printing All RSets");; 2333 heap_region_iterate(&cl); 2334 } 2335 #endif // PRODUCT 2336 2337 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() { 2338 2339 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes; 2340 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes; 2341 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked(); 2342 2343 size_t eden_capacity_bytes = 2344 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes; 2345 2346 VirtualSpaceSummary heap_summary = create_heap_space_summary(); 2347 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, 2348 eden_capacity_bytes, survivor_used_bytes, num_regions()); 2349 } 2350 2351 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) { 2352 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(), 2353 stats->unused(), stats->used(), stats->region_end_waste(), 2354 stats->regions_filled(), stats->direct_allocated(), 2355 stats->failure_used(), stats->failure_waste()); 2356 } 2357 2358 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 2359 const G1HeapSummary& heap_summary = create_g1_heap_summary(); 2360 gc_tracer->report_gc_heap_summary(when, heap_summary); 2361 2362 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 2363 gc_tracer->report_metaspace_summary(when, metaspace_summary); 2364 } 2365 2366 G1CollectedHeap* G1CollectedHeap::heap() { 2367 CollectedHeap* heap = Universe::heap(); 2368 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()"); 2369 assert(heap->kind() == CollectedHeap::G1, "Invalid name"); 2370 return (G1CollectedHeap*)heap; 2371 } 2372 2373 void G1CollectedHeap::gc_prologue(bool full) { 2374 // always_do_update_barrier = false; 2375 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 2376 2377 // This summary needs to be printed before incrementing total collections. 2378 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections()); 2379 2380 // Update common counters. 2381 increment_total_collections(full /* full gc */); 2382 if (full) { 2383 increment_old_marking_cycles_started(); 2384 } 2385 2386 // Fill TLAB's and such 2387 double start = os::elapsedTime(); 2388 accumulate_statistics_all_tlabs(); 2389 ensure_parsability(true); 2390 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2391 } 2392 2393 void G1CollectedHeap::gc_epilogue(bool full) { 2394 // Update common counters. 2395 if (full) { 2396 // Update the number of full collections that have been completed. 2397 increment_old_marking_cycles_completed(false /* concurrent */); 2398 } 2399 2400 // We are at the end of the GC. Total collections has already been increased. 2401 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1); 2402 2403 // FIXME: what is this about? 2404 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled" 2405 // is set. 2406 #if COMPILER2_OR_JVMCI 2407 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 2408 #endif 2409 // always_do_update_barrier = true; 2410 2411 double start = os::elapsedTime(); 2412 resize_all_tlabs(); 2413 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0); 2414 2415 MemoryService::track_memory_usage(); 2416 // We have just completed a GC. Update the soft reference 2417 // policy with the new heap occupancy 2418 Universe::update_heap_info_at_gc(); 2419 } 2420 2421 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size, 2422 uint gc_count_before, 2423 bool* succeeded, 2424 GCCause::Cause gc_cause) { 2425 assert_heap_not_locked_and_not_at_safepoint(); 2426 VM_G1CollectForAllocation op(word_size, 2427 gc_count_before, 2428 gc_cause, 2429 false, /* should_initiate_conc_mark */ 2430 g1_policy()->max_pause_time_ms()); 2431 VMThread::execute(&op); 2432 2433 HeapWord* result = op.result(); 2434 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded(); 2435 assert(result == NULL || ret_succeeded, 2436 "the result should be NULL if the VM did not succeed"); 2437 *succeeded = ret_succeeded; 2438 2439 assert_heap_not_locked(); 2440 return result; 2441 } 2442 2443 void G1CollectedHeap::do_concurrent_mark() { 2444 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 2445 if (!_cm_thread->in_progress()) { 2446 _cm_thread->set_started(); 2447 CGC_lock->notify(); 2448 } 2449 } 2450 2451 size_t G1CollectedHeap::pending_card_num() { 2452 size_t extra_cards = 0; 2453 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) { 2454 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr); 2455 extra_cards += dcq.size(); 2456 } 2457 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set(); 2458 size_t buffer_size = dcqs.buffer_size(); 2459 size_t buffer_num = dcqs.completed_buffers_num(); 2460 2461 return buffer_size * buffer_num + extra_cards; 2462 } 2463 2464 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const { 2465 // We don't nominate objects with many remembered set entries, on 2466 // the assumption that such objects are likely still live. 2467 HeapRegionRemSet* rem_set = r->rem_set(); 2468 2469 return G1EagerReclaimHumongousObjectsWithStaleRefs ? 2470 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) : 2471 G1EagerReclaimHumongousObjects && rem_set->is_empty(); 2472 } 2473 2474 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure { 2475 private: 2476 size_t _total_humongous; 2477 size_t _candidate_humongous; 2478 2479 DirtyCardQueue _dcq; 2480 2481 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const { 2482 assert(region->is_starts_humongous(), "Must start a humongous object"); 2483 2484 oop obj = oop(region->bottom()); 2485 2486 // Dead objects cannot be eager reclaim candidates. Due to class 2487 // unloading it is unsafe to query their classes so we return early. 2488 if (g1h->is_obj_dead(obj, region)) { 2489 return false; 2490 } 2491 2492 // If we do not have a complete remembered set for the region, then we can 2493 // not be sure that we have all references to it. 2494 if (!region->rem_set()->is_complete()) { 2495 return false; 2496 } 2497 // Candidate selection must satisfy the following constraints 2498 // while concurrent marking is in progress: 2499 // 2500 // * In order to maintain SATB invariants, an object must not be 2501 // reclaimed if it was allocated before the start of marking and 2502 // has not had its references scanned. Such an object must have 2503 // its references (including type metadata) scanned to ensure no 2504 // live objects are missed by the marking process. Objects 2505 // allocated after the start of concurrent marking don't need to 2506 // be scanned. 2507 // 2508 // * An object must not be reclaimed if it is on the concurrent 2509 // mark stack. Objects allocated after the start of concurrent 2510 // marking are never pushed on the mark stack. 2511 // 2512 // Nominating only objects allocated after the start of concurrent 2513 // marking is sufficient to meet both constraints. This may miss 2514 // some objects that satisfy the constraints, but the marking data 2515 // structures don't support efficiently performing the needed 2516 // additional tests or scrubbing of the mark stack. 2517 // 2518 // However, we presently only nominate is_typeArray() objects. 2519 // A humongous object containing references induces remembered 2520 // set entries on other regions. In order to reclaim such an 2521 // object, those remembered sets would need to be cleaned up. 2522 // 2523 // We also treat is_typeArray() objects specially, allowing them 2524 // to be reclaimed even if allocated before the start of 2525 // concurrent mark. For this we rely on mark stack insertion to 2526 // exclude is_typeArray() objects, preventing reclaiming an object 2527 // that is in the mark stack. We also rely on the metadata for 2528 // such objects to be built-in and so ensured to be kept live. 2529 // Frequent allocation and drop of large binary blobs is an 2530 // important use case for eager reclaim, and this special handling 2531 // may reduce needed headroom. 2532 2533 return obj->is_typeArray() && 2534 g1h->is_potential_eager_reclaim_candidate(region); 2535 } 2536 2537 public: 2538 RegisterHumongousWithInCSetFastTestClosure() 2539 : _total_humongous(0), 2540 _candidate_humongous(0), 2541 _dcq(&G1BarrierSet::dirty_card_queue_set()) { 2542 } 2543 2544 virtual bool do_heap_region(HeapRegion* r) { 2545 if (!r->is_starts_humongous()) { 2546 return false; 2547 } 2548 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 2549 2550 bool is_candidate = humongous_region_is_candidate(g1h, r); 2551 uint rindex = r->hrm_index(); 2552 g1h->set_humongous_reclaim_candidate(rindex, is_candidate); 2553 if (is_candidate) { 2554 _candidate_humongous++; 2555 g1h->register_humongous_region_with_cset(rindex); 2556 // Is_candidate already filters out humongous object with large remembered sets. 2557 // If we have a humongous object with a few remembered sets, we simply flush these 2558 // remembered set entries into the DCQS. That will result in automatic 2559 // re-evaluation of their remembered set entries during the following evacuation 2560 // phase. 2561 if (!r->rem_set()->is_empty()) { 2562 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries), 2563 "Found a not-small remembered set here. This is inconsistent with previous assumptions."); 2564 G1CardTable* ct = g1h->card_table(); 2565 HeapRegionRemSetIterator hrrs(r->rem_set()); 2566 size_t card_index; 2567 while (hrrs.has_next(card_index)) { 2568 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index); 2569 // The remembered set might contain references to already freed 2570 // regions. Filter out such entries to avoid failing card table 2571 // verification. 2572 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) { 2573 if (*card_ptr != G1CardTable::dirty_card_val()) { 2574 *card_ptr = G1CardTable::dirty_card_val(); 2575 _dcq.enqueue(card_ptr); 2576 } 2577 } 2578 } 2579 assert(hrrs.n_yielded() == r->rem_set()->occupied(), 2580 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries", 2581 hrrs.n_yielded(), r->rem_set()->occupied()); 2582 // We should only clear the card based remembered set here as we will not 2583 // implicitly rebuild anything else during eager reclaim. Note that at the moment 2584 // (and probably never) we do not enter this path if there are other kind of 2585 // remembered sets for this region. 2586 r->rem_set()->clear_locked(true /* only_cardset */); 2587 // Clear_locked() above sets the state to Empty. However we want to continue 2588 // collecting remembered set entries for humongous regions that were not 2589 // reclaimed. 2590 r->rem_set()->set_state_complete(); 2591 } 2592 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty."); 2593 } 2594 _total_humongous++; 2595 2596 return false; 2597 } 2598 2599 size_t total_humongous() const { return _total_humongous; } 2600 size_t candidate_humongous() const { return _candidate_humongous; } 2601 2602 void flush_rem_set_entries() { _dcq.flush(); } 2603 }; 2604 2605 void G1CollectedHeap::register_humongous_regions_with_cset() { 2606 if (!G1EagerReclaimHumongousObjects) { 2607 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0); 2608 return; 2609 } 2610 double time = os::elapsed_counter(); 2611 2612 // Collect reclaim candidate information and register candidates with cset. 2613 RegisterHumongousWithInCSetFastTestClosure cl; 2614 heap_region_iterate(&cl); 2615 2616 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0; 2617 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time, 2618 cl.total_humongous(), 2619 cl.candidate_humongous()); 2620 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0; 2621 2622 // Finally flush all remembered set entries to re-check into the global DCQS. 2623 cl.flush_rem_set_entries(); 2624 } 2625 2626 class VerifyRegionRemSetClosure : public HeapRegionClosure { 2627 public: 2628 bool do_heap_region(HeapRegion* hr) { 2629 if (!hr->is_archive() && !hr->is_continues_humongous()) { 2630 hr->verify_rem_set(); 2631 } 2632 return false; 2633 } 2634 }; 2635 2636 uint G1CollectedHeap::num_task_queues() const { 2637 return _task_queues->size(); 2638 } 2639 2640 #if TASKQUEUE_STATS 2641 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) { 2642 st->print_raw_cr("GC Task Stats"); 2643 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr(); 2644 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr(); 2645 } 2646 2647 void G1CollectedHeap::print_taskqueue_stats() const { 2648 if (!log_is_enabled(Trace, gc, task, stats)) { 2649 return; 2650 } 2651 Log(gc, task, stats) log; 2652 ResourceMark rm; 2653 LogStream ls(log.trace()); 2654 outputStream* st = &ls; 2655 2656 print_taskqueue_stats_hdr(st); 2657 2658 TaskQueueStats totals; 2659 const uint n = num_task_queues(); 2660 for (uint i = 0; i < n; ++i) { 2661 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr(); 2662 totals += task_queue(i)->stats; 2663 } 2664 st->print_raw("tot "); totals.print(st); st->cr(); 2665 2666 DEBUG_ONLY(totals.verify()); 2667 } 2668 2669 void G1CollectedHeap::reset_taskqueue_stats() { 2670 const uint n = num_task_queues(); 2671 for (uint i = 0; i < n; ++i) { 2672 task_queue(i)->stats.reset(); 2673 } 2674 } 2675 #endif // TASKQUEUE_STATS 2676 2677 void G1CollectedHeap::wait_for_root_region_scanning() { 2678 double scan_wait_start = os::elapsedTime(); 2679 // We have to wait until the CM threads finish scanning the 2680 // root regions as it's the only way to ensure that all the 2681 // objects on them have been correctly scanned before we start 2682 // moving them during the GC. 2683 bool waited = _cm->root_regions()->wait_until_scan_finished(); 2684 double wait_time_ms = 0.0; 2685 if (waited) { 2686 double scan_wait_end = os::elapsedTime(); 2687 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0; 2688 } 2689 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms); 2690 } 2691 2692 class G1PrintCollectionSetClosure : public HeapRegionClosure { 2693 private: 2694 G1HRPrinter* _hr_printer; 2695 public: 2696 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { } 2697 2698 virtual bool do_heap_region(HeapRegion* r) { 2699 _hr_printer->cset(r); 2700 return false; 2701 } 2702 }; 2703 2704 void G1CollectedHeap::start_new_collection_set() { 2705 collection_set()->start_incremental_building(); 2706 2707 clear_cset_fast_test(); 2708 2709 guarantee(_eden.length() == 0, "eden should have been cleared"); 2710 g1_policy()->transfer_survivors_to_cset(survivor()); 2711 } 2712 2713 bool 2714 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { 2715 assert_at_safepoint_on_vm_thread(); 2716 guarantee(!is_gc_active(), "collection is not reentrant"); 2717 2718 if (GCLocker::check_active_before_gc()) { 2719 return false; 2720 } 2721 2722 _gc_timer_stw->register_gc_start(); 2723 2724 GCIdMark gc_id_mark; 2725 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start()); 2726 2727 SvcGCMarker sgcm(SvcGCMarker::MINOR); 2728 ResourceMark rm; 2729 2730 g1_policy()->note_gc_start(); 2731 2732 wait_for_root_region_scanning(); 2733 2734 print_heap_before_gc(); 2735 print_heap_regions(); 2736 trace_heap_before_gc(_gc_tracer_stw); 2737 2738 _verifier->verify_region_sets_optional(); 2739 _verifier->verify_dirty_young_regions(); 2740 2741 // We should not be doing initial mark unless the conc mark thread is running 2742 if (!_cm_thread->should_terminate()) { 2743 // This call will decide whether this pause is an initial-mark 2744 // pause. If it is, in_initial_mark_gc() will return true 2745 // for the duration of this pause. 2746 g1_policy()->decide_on_conc_mark_initiation(); 2747 } 2748 2749 // We do not allow initial-mark to be piggy-backed on a mixed GC. 2750 assert(!collector_state()->in_initial_mark_gc() || 2751 collector_state()->in_young_only_phase(), "sanity"); 2752 2753 // We also do not allow mixed GCs during marking. 2754 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity"); 2755 2756 // Record whether this pause is an initial mark. When the current 2757 // thread has completed its logging output and it's safe to signal 2758 // the CM thread, the flag's value in the policy has been reset. 2759 bool should_start_conc_mark = collector_state()->in_initial_mark_gc(); 2760 2761 // Inner scope for scope based logging, timers, and stats collection 2762 { 2763 EvacuationInfo evacuation_info; 2764 2765 if (collector_state()->in_initial_mark_gc()) { 2766 // We are about to start a marking cycle, so we increment the 2767 // full collection counter. 2768 increment_old_marking_cycles_started(); 2769 _cm->gc_tracer_cm()->set_gc_cause(gc_cause()); 2770 } 2771 2772 _gc_tracer_stw->report_yc_type(collector_state()->yc_type()); 2773 2774 GCTraceCPUTime tcpu; 2775 2776 G1HeapVerifier::G1VerifyType verify_type; 2777 FormatBuffer<> gc_string("Pause "); 2778 if (collector_state()->in_initial_mark_gc()) { 2779 gc_string.append("Initial Mark"); 2780 verify_type = G1HeapVerifier::G1VerifyInitialMark; 2781 } else if (collector_state()->in_young_only_phase()) { 2782 gc_string.append("Young"); 2783 verify_type = G1HeapVerifier::G1VerifyYoungOnly; 2784 } else { 2785 gc_string.append("Mixed"); 2786 verify_type = G1HeapVerifier::G1VerifyMixed; 2787 } 2788 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true); 2789 2790 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(), 2791 workers()->active_workers(), 2792 Threads::number_of_non_daemon_threads()); 2793 active_workers = workers()->update_active_workers(active_workers); 2794 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers()); 2795 2796 TraceCollectorStats tcs(g1mm()->incremental_collection_counters()); 2797 TraceMemoryManagerStats tms(&_memory_manager, gc_cause()); 2798 2799 G1HeapTransition heap_transition(this); 2800 size_t heap_used_bytes_before_gc = used(); 2801 2802 // Don't dynamically change the number of GC threads this early. A value of 2803 // 0 is used to indicate serial work. When parallel work is done, 2804 // it will be set. 2805 2806 { // Call to jvmpi::post_class_unload_events must occur outside of active GC 2807 IsGCActiveMark x; 2808 2809 gc_prologue(false); 2810 2811 if (VerifyRememberedSets) { 2812 log_info(gc, verify)("[Verifying RemSets before GC]"); 2813 VerifyRegionRemSetClosure v_cl; 2814 heap_region_iterate(&v_cl); 2815 } 2816 2817 _verifier->verify_before_gc(verify_type); 2818 2819 _verifier->check_bitmaps("GC Start"); 2820 2821 #if COMPILER2_OR_JVMCI 2822 DerivedPointerTable::clear(); 2823 #endif 2824 2825 // Please see comment in g1CollectedHeap.hpp and 2826 // G1CollectedHeap::ref_processing_init() to see how 2827 // reference processing currently works in G1. 2828 2829 // Enable discovery in the STW reference processor 2830 _ref_processor_stw->enable_discovery(); 2831 2832 { 2833 // We want to temporarily turn off discovery by the 2834 // CM ref processor, if necessary, and turn it back on 2835 // on again later if we do. Using a scoped 2836 // NoRefDiscovery object will do this. 2837 NoRefDiscovery no_cm_discovery(_ref_processor_cm); 2838 2839 // Forget the current alloc region (we might even choose it to be part 2840 // of the collection set!). 2841 _allocator->release_mutator_alloc_region(); 2842 2843 // This timing is only used by the ergonomics to handle our pause target. 2844 // It is unclear why this should not include the full pause. We will 2845 // investigate this in CR 7178365. 2846 // 2847 // Preserving the old comment here if that helps the investigation: 2848 // 2849 // The elapsed time induced by the start time below deliberately elides 2850 // the possible verification above. 2851 double sample_start_time_sec = os::elapsedTime(); 2852 2853 g1_policy()->record_collection_pause_start(sample_start_time_sec); 2854 2855 if (collector_state()->in_initial_mark_gc()) { 2856 concurrent_mark()->pre_initial_mark(); 2857 } 2858 2859 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor); 2860 2861 evacuation_info.set_collectionset_regions(collection_set()->region_length()); 2862 2863 // Make sure the remembered sets are up to date. This needs to be 2864 // done before register_humongous_regions_with_cset(), because the 2865 // remembered sets are used there to choose eager reclaim candidates. 2866 // If the remembered sets are not up to date we might miss some 2867 // entries that need to be handled. 2868 g1_rem_set()->cleanupHRRS(); 2869 2870 register_humongous_regions_with_cset(); 2871 2872 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table."); 2873 2874 // We call this after finalize_cset() to 2875 // ensure that the CSet has been finalized. 2876 _cm->verify_no_cset_oops(); 2877 2878 if (_hr_printer.is_active()) { 2879 G1PrintCollectionSetClosure cl(&_hr_printer); 2880 _collection_set.iterate(&cl); 2881 } 2882 2883 // Initialize the GC alloc regions. 2884 _allocator->init_gc_alloc_regions(evacuation_info); 2885 2886 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length()); 2887 pre_evacuate_collection_set(); 2888 2889 // Actually do the work... 2890 evacuate_collection_set(&per_thread_states); 2891 2892 post_evacuate_collection_set(evacuation_info, &per_thread_states); 2893 2894 const size_t* surviving_young_words = per_thread_states.surviving_young_words(); 2895 free_collection_set(&_collection_set, evacuation_info, surviving_young_words); 2896 2897 eagerly_reclaim_humongous_regions(); 2898 2899 record_obj_copy_mem_stats(); 2900 _survivor_evac_stats.adjust_desired_plab_sz(); 2901 _old_evac_stats.adjust_desired_plab_sz(); 2902 2903 double start = os::elapsedTime(); 2904 start_new_collection_set(); 2905 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0); 2906 2907 if (evacuation_failed()) { 2908 set_used(recalculate_used()); 2909 if (_archive_allocator != NULL) { 2910 _archive_allocator->clear_used(); 2911 } 2912 for (uint i = 0; i < ParallelGCThreads; i++) { 2913 if (_evacuation_failed_info_array[i].has_failed()) { 2914 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]); 2915 } 2916 } 2917 } else { 2918 // The "used" of the the collection set have already been subtracted 2919 // when they were freed. Add in the bytes evacuated. 2920 increase_used(g1_policy()->bytes_copied_during_gc()); 2921 } 2922 2923 if (collector_state()->in_initial_mark_gc()) { 2924 // We have to do this before we notify the CM threads that 2925 // they can start working to make sure that all the 2926 // appropriate initialization is done on the CM object. 2927 concurrent_mark()->post_initial_mark(); 2928 // Note that we don't actually trigger the CM thread at 2929 // this point. We do that later when we're sure that 2930 // the current thread has completed its logging output. 2931 } 2932 2933 allocate_dummy_regions(); 2934 2935 _allocator->init_mutator_alloc_region(); 2936 2937 { 2938 size_t expand_bytes = _heap_sizing_policy->expansion_amount(); 2939 if (expand_bytes > 0) { 2940 size_t bytes_before = capacity(); 2941 // No need for an ergo logging here, 2942 // expansion_amount() does this when it returns a value > 0. 2943 double expand_ms; 2944 if (!expand(expand_bytes, _workers, &expand_ms)) { 2945 // We failed to expand the heap. Cannot do anything about it. 2946 } 2947 g1_policy()->phase_times()->record_expand_heap_time(expand_ms); 2948 } 2949 } 2950 2951 // We redo the verification but now wrt to the new CSet which 2952 // has just got initialized after the previous CSet was freed. 2953 _cm->verify_no_cset_oops(); 2954 2955 // This timing is only used by the ergonomics to handle our pause target. 2956 // It is unclear why this should not include the full pause. We will 2957 // investigate this in CR 7178365. 2958 double sample_end_time_sec = os::elapsedTime(); 2959 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS; 2960 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards); 2961 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc); 2962 2963 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before()); 2964 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc()); 2965 2966 if (VerifyRememberedSets) { 2967 log_info(gc, verify)("[Verifying RemSets after GC]"); 2968 VerifyRegionRemSetClosure v_cl; 2969 heap_region_iterate(&v_cl); 2970 } 2971 2972 _verifier->verify_after_gc(verify_type); 2973 _verifier->check_bitmaps("GC End"); 2974 2975 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition"); 2976 _ref_processor_stw->verify_no_references_recorded(); 2977 2978 // CM reference discovery will be re-enabled if necessary. 2979 } 2980 2981 #ifdef TRACESPINNING 2982 ParallelTaskTerminator::print_termination_counts(); 2983 #endif 2984 2985 gc_epilogue(false); 2986 } 2987 2988 // Print the remainder of the GC log output. 2989 if (evacuation_failed()) { 2990 log_info(gc)("To-space exhausted"); 2991 } 2992 2993 g1_policy()->print_phases(); 2994 heap_transition.print(); 2995 2996 // It is not yet to safe to tell the concurrent mark to 2997 // start as we have some optional output below. We don't want the 2998 // output from the concurrent mark thread interfering with this 2999 // logging output either. 3000 3001 _hrm.verify_optional(); 3002 _verifier->verify_region_sets_optional(); 3003 3004 TASKQUEUE_STATS_ONLY(print_taskqueue_stats()); 3005 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats()); 3006 3007 print_heap_after_gc(); 3008 print_heap_regions(); 3009 trace_heap_after_gc(_gc_tracer_stw); 3010 3011 // We must call G1MonitoringSupport::update_sizes() in the same scoping level 3012 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the 3013 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated 3014 // before any GC notifications are raised. 3015 g1mm()->update_sizes(); 3016 3017 _gc_tracer_stw->report_evacuation_info(&evacuation_info); 3018 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold()); 3019 _gc_timer_stw->register_gc_end(); 3020 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions()); 3021 } 3022 // It should now be safe to tell the concurrent mark thread to start 3023 // without its logging output interfering with the logging output 3024 // that came from the pause. 3025 3026 if (should_start_conc_mark) { 3027 // CAUTION: after the doConcurrentMark() call below, 3028 // the concurrent marking thread(s) could be running 3029 // concurrently with us. Make sure that anything after 3030 // this point does not assume that we are the only GC thread 3031 // running. Note: of course, the actual marking work will 3032 // not start until the safepoint itself is released in 3033 // SuspendibleThreadSet::desynchronize(). 3034 do_concurrent_mark(); 3035 } 3036 3037 return true; 3038 } 3039 3040 void G1CollectedHeap::remove_self_forwarding_pointers() { 3041 G1ParRemoveSelfForwardPtrsTask rsfp_task; 3042 workers()->run_task(&rsfp_task); 3043 } 3044 3045 void G1CollectedHeap::restore_after_evac_failure() { 3046 double remove_self_forwards_start = os::elapsedTime(); 3047 3048 remove_self_forwarding_pointers(); 3049 SharedRestorePreservedMarksTaskExecutor task_executor(workers()); 3050 _preserved_marks_set.restore(&task_executor); 3051 3052 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0); 3053 } 3054 3055 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) { 3056 if (!_evacuation_failed) { 3057 _evacuation_failed = true; 3058 } 3059 3060 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size()); 3061 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m); 3062 } 3063 3064 bool G1ParEvacuateFollowersClosure::offer_termination() { 3065 G1ParScanThreadState* const pss = par_scan_state(); 3066 start_term_time(); 3067 const bool res = terminator()->offer_termination(); 3068 end_term_time(); 3069 return res; 3070 } 3071 3072 void G1ParEvacuateFollowersClosure::do_void() { 3073 G1ParScanThreadState* const pss = par_scan_state(); 3074 pss->trim_queue(); 3075 do { 3076 pss->steal_and_trim_queue(queues()); 3077 } while (!offer_termination()); 3078 } 3079 3080 class G1ParTask : public AbstractGangTask { 3081 protected: 3082 G1CollectedHeap* _g1h; 3083 G1ParScanThreadStateSet* _pss; 3084 RefToScanQueueSet* _queues; 3085 G1RootProcessor* _root_processor; 3086 ParallelTaskTerminator _terminator; 3087 uint _n_workers; 3088 3089 public: 3090 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers) 3091 : AbstractGangTask("G1 collection"), 3092 _g1h(g1h), 3093 _pss(per_thread_states), 3094 _queues(task_queues), 3095 _root_processor(root_processor), 3096 _terminator(n_workers, _queues), 3097 _n_workers(n_workers) 3098 {} 3099 3100 void work(uint worker_id) { 3101 if (worker_id >= _n_workers) return; // no work needed this round 3102 3103 double start_sec = os::elapsedTime(); 3104 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec); 3105 3106 { 3107 ResourceMark rm; 3108 HandleMark hm; 3109 3110 ReferenceProcessor* rp = _g1h->ref_processor_stw(); 3111 3112 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3113 pss->set_ref_processor(rp); 3114 3115 double start_strong_roots_sec = os::elapsedTime(); 3116 3117 _root_processor->evacuate_roots(pss, worker_id); 3118 3119 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid 3120 // treating the nmethods visited to act as roots for concurrent marking. 3121 // We only want to make sure that the oops in the nmethods are adjusted with regard to the 3122 // objects copied by the current evacuation. 3123 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id); 3124 3125 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec; 3126 3127 double term_sec = 0.0; 3128 size_t evac_term_attempts = 0; 3129 { 3130 double start = os::elapsedTime(); 3131 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator); 3132 evac.do_void(); 3133 3134 evac_term_attempts = evac.term_attempts(); 3135 term_sec = evac.term_time(); 3136 double elapsed_sec = os::elapsedTime() - start; 3137 3138 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times(); 3139 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec); 3140 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec); 3141 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts); 3142 } 3143 3144 assert(pss->queue_is_empty(), "should be empty"); 3145 3146 if (log_is_enabled(Debug, gc, task, stats)) { 3147 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag); 3148 size_t lab_waste; 3149 size_t lab_undo_waste; 3150 pss->waste(lab_waste, lab_undo_waste); 3151 _g1h->print_termination_stats(worker_id, 3152 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */ 3153 strong_roots_sec * 1000.0, /* strong roots time */ 3154 term_sec * 1000.0, /* evac term time */ 3155 evac_term_attempts, /* evac term attempts */ 3156 lab_waste, /* alloc buffer waste */ 3157 lab_undo_waste /* undo waste */ 3158 ); 3159 } 3160 3161 // Close the inner scope so that the ResourceMark and HandleMark 3162 // destructors are executed here and are included as part of the 3163 // "GC Worker Time". 3164 } 3165 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime()); 3166 } 3167 }; 3168 3169 void G1CollectedHeap::print_termination_stats_hdr() { 3170 log_debug(gc, task, stats)("GC Termination Stats"); 3171 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------"); 3172 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo"); 3173 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------"); 3174 } 3175 3176 void G1CollectedHeap::print_termination_stats(uint worker_id, 3177 double elapsed_ms, 3178 double strong_roots_ms, 3179 double term_ms, 3180 size_t term_attempts, 3181 size_t alloc_buffer_waste, 3182 size_t undo_waste) const { 3183 log_debug(gc, task, stats) 3184 ("%3d %9.2f %9.2f %6.2f " 3185 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 3186 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 3187 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms, 3188 term_ms, term_ms * 100 / elapsed_ms, term_attempts, 3189 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 3190 alloc_buffer_waste * HeapWordSize / K, 3191 undo_waste * HeapWordSize / K); 3192 } 3193 3194 class G1StringAndSymbolCleaningTask : public AbstractGangTask { 3195 private: 3196 BoolObjectClosure* _is_alive; 3197 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure; 3198 3199 int _initial_string_table_size; 3200 int _initial_symbol_table_size; 3201 3202 bool _process_strings; 3203 int _strings_processed; 3204 int _strings_removed; 3205 3206 bool _process_symbols; 3207 int _symbols_processed; 3208 int _symbols_removed; 3209 3210 bool _process_string_dedup; 3211 3212 public: 3213 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) : 3214 AbstractGangTask("String/Symbol Unlinking"), 3215 _is_alive(is_alive), 3216 _dedup_closure(is_alive, NULL, false), 3217 _process_strings(process_strings), _strings_processed(0), _strings_removed(0), 3218 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0), 3219 _process_string_dedup(process_string_dedup) { 3220 3221 _initial_string_table_size = StringTable::the_table()->table_size(); 3222 _initial_symbol_table_size = SymbolTable::the_table()->table_size(); 3223 if (process_strings) { 3224 StringTable::clear_parallel_claimed_index(); 3225 } 3226 if (process_symbols) { 3227 SymbolTable::clear_parallel_claimed_index(); 3228 } 3229 } 3230 3231 ~G1StringAndSymbolCleaningTask() { 3232 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size, 3233 "claim value %d after unlink less than initial string table size %d", 3234 StringTable::parallel_claimed_index(), _initial_string_table_size); 3235 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size, 3236 "claim value %d after unlink less than initial symbol table size %d", 3237 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size); 3238 3239 log_info(gc, stringtable)( 3240 "Cleaned string and symbol table, " 3241 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, " 3242 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed", 3243 strings_processed(), strings_removed(), 3244 symbols_processed(), symbols_removed()); 3245 } 3246 3247 void work(uint worker_id) { 3248 int strings_processed = 0; 3249 int strings_removed = 0; 3250 int symbols_processed = 0; 3251 int symbols_removed = 0; 3252 if (_process_strings) { 3253 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed); 3254 Atomic::add(strings_processed, &_strings_processed); 3255 Atomic::add(strings_removed, &_strings_removed); 3256 } 3257 if (_process_symbols) { 3258 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed); 3259 Atomic::add(symbols_processed, &_symbols_processed); 3260 Atomic::add(symbols_removed, &_symbols_removed); 3261 } 3262 if (_process_string_dedup) { 3263 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id); 3264 } 3265 } 3266 3267 size_t strings_processed() const { return (size_t)_strings_processed; } 3268 size_t strings_removed() const { return (size_t)_strings_removed; } 3269 3270 size_t symbols_processed() const { return (size_t)_symbols_processed; } 3271 size_t symbols_removed() const { return (size_t)_symbols_removed; } 3272 }; 3273 3274 class G1CodeCacheUnloadingTask { 3275 private: 3276 static Monitor* _lock; 3277 3278 BoolObjectClosure* const _is_alive; 3279 const bool _unloading_occurred; 3280 const uint _num_workers; 3281 3282 // Variables used to claim nmethods. 3283 CompiledMethod* _first_nmethod; 3284 CompiledMethod* volatile _claimed_nmethod; 3285 3286 // The list of nmethods that need to be processed by the second pass. 3287 CompiledMethod* volatile _postponed_list; 3288 volatile uint _num_entered_barrier; 3289 3290 public: 3291 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) : 3292 _is_alive(is_alive), 3293 _unloading_occurred(unloading_occurred), 3294 _num_workers(num_workers), 3295 _first_nmethod(NULL), 3296 _claimed_nmethod(NULL), 3297 _postponed_list(NULL), 3298 _num_entered_barrier(0) 3299 { 3300 CompiledMethod::increase_unloading_clock(); 3301 // Get first alive nmethod 3302 CompiledMethodIterator iter = CompiledMethodIterator(); 3303 if(iter.next_alive()) { 3304 _first_nmethod = iter.method(); 3305 } 3306 _claimed_nmethod = _first_nmethod; 3307 } 3308 3309 ~G1CodeCacheUnloadingTask() { 3310 CodeCache::verify_clean_inline_caches(); 3311 3312 CodeCache::set_needs_cache_clean(false); 3313 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be"); 3314 3315 CodeCache::verify_icholder_relocations(); 3316 } 3317 3318 private: 3319 void add_to_postponed_list(CompiledMethod* nm) { 3320 CompiledMethod* old; 3321 do { 3322 old = _postponed_list; 3323 nm->set_unloading_next(old); 3324 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old); 3325 } 3326 3327 void clean_nmethod(CompiledMethod* nm) { 3328 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred); 3329 3330 if (postponed) { 3331 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet. 3332 add_to_postponed_list(nm); 3333 } 3334 3335 // Mark that this thread has been cleaned/unloaded. 3336 // After this call, it will be safe to ask if this nmethod was unloaded or not. 3337 nm->set_unloading_clock(CompiledMethod::global_unloading_clock()); 3338 } 3339 3340 void clean_nmethod_postponed(CompiledMethod* nm) { 3341 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred); 3342 } 3343 3344 static const int MaxClaimNmethods = 16; 3345 3346 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) { 3347 CompiledMethod* first; 3348 CompiledMethodIterator last; 3349 3350 do { 3351 *num_claimed_nmethods = 0; 3352 3353 first = _claimed_nmethod; 3354 last = CompiledMethodIterator(first); 3355 3356 if (first != NULL) { 3357 3358 for (int i = 0; i < MaxClaimNmethods; i++) { 3359 if (!last.next_alive()) { 3360 break; 3361 } 3362 claimed_nmethods[i] = last.method(); 3363 (*num_claimed_nmethods)++; 3364 } 3365 } 3366 3367 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first); 3368 } 3369 3370 CompiledMethod* claim_postponed_nmethod() { 3371 CompiledMethod* claim; 3372 CompiledMethod* next; 3373 3374 do { 3375 claim = _postponed_list; 3376 if (claim == NULL) { 3377 return NULL; 3378 } 3379 3380 next = claim->unloading_next(); 3381 3382 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim); 3383 3384 return claim; 3385 } 3386 3387 public: 3388 // Mark that we're done with the first pass of nmethod cleaning. 3389 void barrier_mark(uint worker_id) { 3390 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3391 _num_entered_barrier++; 3392 if (_num_entered_barrier == _num_workers) { 3393 ml.notify_all(); 3394 } 3395 } 3396 3397 // See if we have to wait for the other workers to 3398 // finish their first-pass nmethod cleaning work. 3399 void barrier_wait(uint worker_id) { 3400 if (_num_entered_barrier < _num_workers) { 3401 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag); 3402 while (_num_entered_barrier < _num_workers) { 3403 ml.wait(Mutex::_no_safepoint_check_flag, 0, false); 3404 } 3405 } 3406 } 3407 3408 // Cleaning and unloading of nmethods. Some work has to be postponed 3409 // to the second pass, when we know which nmethods survive. 3410 void work_first_pass(uint worker_id) { 3411 // The first nmethods is claimed by the first worker. 3412 if (worker_id == 0 && _first_nmethod != NULL) { 3413 clean_nmethod(_first_nmethod); 3414 _first_nmethod = NULL; 3415 } 3416 3417 int num_claimed_nmethods; 3418 CompiledMethod* claimed_nmethods[MaxClaimNmethods]; 3419 3420 while (true) { 3421 claim_nmethods(claimed_nmethods, &num_claimed_nmethods); 3422 3423 if (num_claimed_nmethods == 0) { 3424 break; 3425 } 3426 3427 for (int i = 0; i < num_claimed_nmethods; i++) { 3428 clean_nmethod(claimed_nmethods[i]); 3429 } 3430 } 3431 } 3432 3433 void work_second_pass(uint worker_id) { 3434 CompiledMethod* nm; 3435 // Take care of postponed nmethods. 3436 while ((nm = claim_postponed_nmethod()) != NULL) { 3437 clean_nmethod_postponed(nm); 3438 } 3439 } 3440 }; 3441 3442 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never); 3443 3444 class G1KlassCleaningTask : public StackObj { 3445 volatile int _clean_klass_tree_claimed; 3446 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator; 3447 3448 public: 3449 G1KlassCleaningTask() : 3450 _clean_klass_tree_claimed(0), 3451 _klass_iterator() { 3452 } 3453 3454 private: 3455 bool claim_clean_klass_tree_task() { 3456 if (_clean_klass_tree_claimed) { 3457 return false; 3458 } 3459 3460 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0; 3461 } 3462 3463 InstanceKlass* claim_next_klass() { 3464 Klass* klass; 3465 do { 3466 klass =_klass_iterator.next_klass(); 3467 } while (klass != NULL && !klass->is_instance_klass()); 3468 3469 // this can be null so don't call InstanceKlass::cast 3470 return static_cast<InstanceKlass*>(klass); 3471 } 3472 3473 public: 3474 3475 void clean_klass(InstanceKlass* ik) { 3476 ik->clean_weak_instanceklass_links(); 3477 } 3478 3479 void work() { 3480 ResourceMark rm; 3481 3482 // One worker will clean the subklass/sibling klass tree. 3483 if (claim_clean_klass_tree_task()) { 3484 Klass::clean_subklass_tree(); 3485 } 3486 3487 // All workers will help cleaning the classes, 3488 InstanceKlass* klass; 3489 while ((klass = claim_next_klass()) != NULL) { 3490 clean_klass(klass); 3491 } 3492 } 3493 }; 3494 3495 class G1ResolvedMethodCleaningTask : public StackObj { 3496 volatile int _resolved_method_task_claimed; 3497 public: 3498 G1ResolvedMethodCleaningTask() : 3499 _resolved_method_task_claimed(0) {} 3500 3501 bool claim_resolved_method_task() { 3502 if (_resolved_method_task_claimed) { 3503 return false; 3504 } 3505 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0; 3506 } 3507 3508 // These aren't big, one thread can do it all. 3509 void work() { 3510 if (claim_resolved_method_task()) { 3511 ResolvedMethodTable::unlink(); 3512 } 3513 } 3514 }; 3515 3516 3517 // To minimize the remark pause times, the tasks below are done in parallel. 3518 class G1ParallelCleaningTask : public AbstractGangTask { 3519 private: 3520 G1StringAndSymbolCleaningTask _string_symbol_task; 3521 G1CodeCacheUnloadingTask _code_cache_task; 3522 G1KlassCleaningTask _klass_cleaning_task; 3523 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task; 3524 3525 public: 3526 // The constructor is run in the VMThread. 3527 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) : 3528 AbstractGangTask("Parallel Cleaning"), 3529 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()), 3530 _code_cache_task(num_workers, is_alive, unloading_occurred), 3531 _klass_cleaning_task(), 3532 _resolved_method_cleaning_task() { 3533 } 3534 3535 // The parallel work done by all worker threads. 3536 void work(uint worker_id) { 3537 // Do first pass of code cache cleaning. 3538 _code_cache_task.work_first_pass(worker_id); 3539 3540 // Let the threads mark that the first pass is done. 3541 _code_cache_task.barrier_mark(worker_id); 3542 3543 // Clean the Strings and Symbols. 3544 _string_symbol_task.work(worker_id); 3545 3546 // Clean unreferenced things in the ResolvedMethodTable 3547 _resolved_method_cleaning_task.work(); 3548 3549 // Wait for all workers to finish the first code cache cleaning pass. 3550 _code_cache_task.barrier_wait(worker_id); 3551 3552 // Do the second code cache cleaning work, which realize on 3553 // the liveness information gathered during the first pass. 3554 _code_cache_task.work_second_pass(worker_id); 3555 3556 // Clean all klasses that were not unloaded. 3557 _klass_cleaning_task.work(); 3558 } 3559 }; 3560 3561 3562 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive, 3563 bool class_unloading_occurred) { 3564 uint n_workers = workers()->active_workers(); 3565 3566 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred); 3567 workers()->run_task(&g1_unlink_task); 3568 } 3569 3570 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive, 3571 bool process_strings, 3572 bool process_symbols, 3573 bool process_string_dedup) { 3574 if (!process_strings && !process_symbols && !process_string_dedup) { 3575 // Nothing to clean. 3576 return; 3577 } 3578 3579 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup); 3580 workers()->run_task(&g1_unlink_task); 3581 3582 } 3583 3584 class G1RedirtyLoggedCardsTask : public AbstractGangTask { 3585 private: 3586 DirtyCardQueueSet* _queue; 3587 G1CollectedHeap* _g1h; 3588 public: 3589 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"), 3590 _queue(queue), _g1h(g1h) { } 3591 3592 virtual void work(uint worker_id) { 3593 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times(); 3594 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id); 3595 3596 RedirtyLoggedCardTableEntryClosure cl(_g1h); 3597 _queue->par_apply_closure_to_all_completed_buffers(&cl); 3598 3599 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied()); 3600 } 3601 }; 3602 3603 void G1CollectedHeap::redirty_logged_cards() { 3604 double redirty_logged_cards_start = os::elapsedTime(); 3605 3606 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this); 3607 dirty_card_queue_set().reset_for_par_iteration(); 3608 workers()->run_task(&redirty_task); 3609 3610 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set(); 3611 dcq.merge_bufferlists(&dirty_card_queue_set()); 3612 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed"); 3613 3614 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0); 3615 } 3616 3617 // Weak Reference Processing support 3618 3619 bool G1STWIsAliveClosure::do_object_b(oop p) { 3620 // An object is reachable if it is outside the collection set, 3621 // or is inside and copied. 3622 return !_g1h->is_in_cset(p) || p->is_forwarded(); 3623 } 3624 3625 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) { 3626 assert(obj != NULL, "must not be NULL"); 3627 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj)); 3628 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below 3629 // may falsely indicate that this is not the case here: however the collection set only 3630 // contains old regions when concurrent mark is not running. 3631 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor(); 3632 } 3633 3634 // Non Copying Keep Alive closure 3635 class G1KeepAliveClosure: public OopClosure { 3636 G1CollectedHeap*_g1h; 3637 public: 3638 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {} 3639 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); } 3640 void do_oop(oop* p) { 3641 oop obj = *p; 3642 assert(obj != NULL, "the caller should have filtered out NULL values"); 3643 3644 const InCSetState cset_state =_g1h->in_cset_state(obj); 3645 if (!cset_state.is_in_cset_or_humongous()) { 3646 return; 3647 } 3648 if (cset_state.is_in_cset()) { 3649 assert( obj->is_forwarded(), "invariant" ); 3650 *p = obj->forwardee(); 3651 } else { 3652 assert(!obj->is_forwarded(), "invariant" ); 3653 assert(cset_state.is_humongous(), 3654 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()); 3655 _g1h->set_humongous_is_live(obj); 3656 } 3657 } 3658 }; 3659 3660 // Copying Keep Alive closure - can be called from both 3661 // serial and parallel code as long as different worker 3662 // threads utilize different G1ParScanThreadState instances 3663 // and different queues. 3664 3665 class G1CopyingKeepAliveClosure: public OopClosure { 3666 G1CollectedHeap* _g1h; 3667 OopClosure* _copy_non_heap_obj_cl; 3668 G1ParScanThreadState* _par_scan_state; 3669 3670 public: 3671 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h, 3672 OopClosure* non_heap_obj_cl, 3673 G1ParScanThreadState* pss): 3674 _g1h(g1h), 3675 _copy_non_heap_obj_cl(non_heap_obj_cl), 3676 _par_scan_state(pss) 3677 {} 3678 3679 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3680 virtual void do_oop( oop* p) { do_oop_work(p); } 3681 3682 template <class T> void do_oop_work(T* p) { 3683 oop obj = RawAccess<>::oop_load(p); 3684 3685 if (_g1h->is_in_cset_or_humongous(obj)) { 3686 // If the referent object has been forwarded (either copied 3687 // to a new location or to itself in the event of an 3688 // evacuation failure) then we need to update the reference 3689 // field and, if both reference and referent are in the G1 3690 // heap, update the RSet for the referent. 3691 // 3692 // If the referent has not been forwarded then we have to keep 3693 // it alive by policy. Therefore we have copy the referent. 3694 // 3695 // If the reference field is in the G1 heap then we can push 3696 // on the PSS queue. When the queue is drained (after each 3697 // phase of reference processing) the object and it's followers 3698 // will be copied, the reference field set to point to the 3699 // new location, and the RSet updated. Otherwise we need to 3700 // use the the non-heap or metadata closures directly to copy 3701 // the referent object and update the pointer, while avoiding 3702 // updating the RSet. 3703 3704 if (_g1h->is_in_g1_reserved(p)) { 3705 _par_scan_state->push_on_queue(p); 3706 } else { 3707 assert(!Metaspace::contains((const void*)p), 3708 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)); 3709 _copy_non_heap_obj_cl->do_oop(p); 3710 } 3711 } 3712 } 3713 }; 3714 3715 // Serial drain queue closure. Called as the 'complete_gc' 3716 // closure for each discovered list in some of the 3717 // reference processing phases. 3718 3719 class G1STWDrainQueueClosure: public VoidClosure { 3720 protected: 3721 G1CollectedHeap* _g1h; 3722 G1ParScanThreadState* _par_scan_state; 3723 3724 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 3725 3726 public: 3727 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : 3728 _g1h(g1h), 3729 _par_scan_state(pss) 3730 { } 3731 3732 void do_void() { 3733 G1ParScanThreadState* const pss = par_scan_state(); 3734 pss->trim_queue(); 3735 } 3736 }; 3737 3738 // Parallel Reference Processing closures 3739 3740 // Implementation of AbstractRefProcTaskExecutor for parallel reference 3741 // processing during G1 evacuation pauses. 3742 3743 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 3744 private: 3745 G1CollectedHeap* _g1h; 3746 G1ParScanThreadStateSet* _pss; 3747 RefToScanQueueSet* _queues; 3748 WorkGang* _workers; 3749 uint _active_workers; 3750 3751 public: 3752 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h, 3753 G1ParScanThreadStateSet* per_thread_states, 3754 WorkGang* workers, 3755 RefToScanQueueSet *task_queues, 3756 uint n_workers) : 3757 _g1h(g1h), 3758 _pss(per_thread_states), 3759 _queues(task_queues), 3760 _workers(workers), 3761 _active_workers(n_workers) 3762 { 3763 g1h->ref_processor_stw()->set_active_mt_degree(n_workers); 3764 } 3765 3766 // Executes the given task using concurrent marking worker threads. 3767 virtual void execute(ProcessTask& task); 3768 virtual void execute(EnqueueTask& task); 3769 }; 3770 3771 // Gang task for possibly parallel reference processing 3772 3773 class G1STWRefProcTaskProxy: public AbstractGangTask { 3774 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 3775 ProcessTask& _proc_task; 3776 G1CollectedHeap* _g1h; 3777 G1ParScanThreadStateSet* _pss; 3778 RefToScanQueueSet* _task_queues; 3779 ParallelTaskTerminator* _terminator; 3780 3781 public: 3782 G1STWRefProcTaskProxy(ProcessTask& proc_task, 3783 G1CollectedHeap* g1h, 3784 G1ParScanThreadStateSet* per_thread_states, 3785 RefToScanQueueSet *task_queues, 3786 ParallelTaskTerminator* terminator) : 3787 AbstractGangTask("Process reference objects in parallel"), 3788 _proc_task(proc_task), 3789 _g1h(g1h), 3790 _pss(per_thread_states), 3791 _task_queues(task_queues), 3792 _terminator(terminator) 3793 {} 3794 3795 virtual void work(uint worker_id) { 3796 // The reference processing task executed by a single worker. 3797 ResourceMark rm; 3798 HandleMark hm; 3799 3800 G1STWIsAliveClosure is_alive(_g1h); 3801 3802 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id); 3803 pss->set_ref_processor(NULL); 3804 3805 // Keep alive closure. 3806 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss); 3807 3808 // Complete GC closure 3809 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator); 3810 3811 // Call the reference processing task's work routine. 3812 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue); 3813 3814 // Note we cannot assert that the refs array is empty here as not all 3815 // of the processing tasks (specifically phase2 - pp2_work) execute 3816 // the complete_gc closure (which ordinarily would drain the queue) so 3817 // the queue may not be empty. 3818 } 3819 }; 3820 3821 // Driver routine for parallel reference processing. 3822 // Creates an instance of the ref processing gang 3823 // task and has the worker threads execute it. 3824 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) { 3825 assert(_workers != NULL, "Need parallel worker threads."); 3826 3827 ParallelTaskTerminator terminator(_active_workers, _queues); 3828 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator); 3829 3830 _workers->run_task(&proc_task_proxy); 3831 } 3832 3833 // Gang task for parallel reference enqueueing. 3834 3835 class G1STWRefEnqueueTaskProxy: public AbstractGangTask { 3836 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 3837 EnqueueTask& _enq_task; 3838 3839 public: 3840 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) : 3841 AbstractGangTask("Enqueue reference objects in parallel"), 3842 _enq_task(enq_task) 3843 { } 3844 3845 virtual void work(uint worker_id) { 3846 _enq_task.work(worker_id); 3847 } 3848 }; 3849 3850 // Driver routine for parallel reference enqueueing. 3851 // Creates an instance of the ref enqueueing gang 3852 // task and has the worker threads execute it. 3853 3854 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) { 3855 assert(_workers != NULL, "Need parallel worker threads."); 3856 3857 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task); 3858 3859 _workers->run_task(&enq_task_proxy); 3860 } 3861 3862 // End of weak reference support closures 3863 3864 // Weak Reference processing during an evacuation pause (part 1). 3865 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3866 double ref_proc_start = os::elapsedTime(); 3867 3868 ReferenceProcessor* rp = _ref_processor_stw; 3869 assert(rp->discovery_enabled(), "should have been enabled"); 3870 3871 // Closure to test whether a referent is alive. 3872 G1STWIsAliveClosure is_alive(this); 3873 3874 // Even when parallel reference processing is enabled, the processing 3875 // of JNI refs is serial and performed serially by the current thread 3876 // rather than by a worker. The following PSS will be used for processing 3877 // JNI refs. 3878 3879 // Use only a single queue for this PSS. 3880 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0); 3881 pss->set_ref_processor(NULL); 3882 assert(pss->queue_is_empty(), "pre-condition"); 3883 3884 // Keep alive closure. 3885 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss); 3886 3887 // Serial Complete GC closure 3888 G1STWDrainQueueClosure drain_queue(this, pss); 3889 3890 // Setup the soft refs policy... 3891 rp->setup_policy(false); 3892 3893 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3894 3895 ReferenceProcessorStats stats; 3896 if (!rp->processing_is_mt()) { 3897 // Serial reference processing... 3898 stats = rp->process_discovered_references(&is_alive, 3899 &keep_alive, 3900 &drain_queue, 3901 NULL, 3902 pt); 3903 } else { 3904 uint no_of_gc_workers = workers()->active_workers(); 3905 3906 // Parallel reference processing 3907 assert(no_of_gc_workers <= rp->max_num_queues(), 3908 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3909 no_of_gc_workers, rp->max_num_queues()); 3910 3911 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers); 3912 stats = rp->process_discovered_references(&is_alive, 3913 &keep_alive, 3914 &drain_queue, 3915 &par_task_executor, 3916 pt); 3917 } 3918 3919 _gc_tracer_stw->report_gc_reference_stats(stats); 3920 3921 // We have completed copying any necessary live referent objects. 3922 assert(pss->queue_is_empty(), "both queue and overflow should be empty"); 3923 3924 double ref_proc_time = os::elapsedTime() - ref_proc_start; 3925 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0); 3926 } 3927 3928 // Weak Reference processing during an evacuation pause (part 2). 3929 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) { 3930 double ref_enq_start = os::elapsedTime(); 3931 3932 ReferenceProcessor* rp = _ref_processor_stw; 3933 assert(!rp->discovery_enabled(), "should have been disabled as part of processing"); 3934 3935 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times(); 3936 3937 // Now enqueue any remaining on the discovered lists on to 3938 // the pending list. 3939 if (!rp->processing_is_mt()) { 3940 // Serial reference processing... 3941 rp->enqueue_discovered_references(NULL, pt); 3942 } else { 3943 // Parallel reference enqueueing 3944 3945 uint n_workers = workers()->active_workers(); 3946 3947 assert(n_workers <= rp->max_num_queues(), 3948 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u", 3949 n_workers, rp->max_num_queues()); 3950 3951 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers); 3952 rp->enqueue_discovered_references(&par_task_executor, pt); 3953 } 3954 3955 rp->verify_no_references_recorded(); 3956 assert(!rp->discovery_enabled(), "should have been disabled"); 3957 3958 // If during an initial mark pause we install a pending list head which is not otherwise reachable 3959 // ensure that it is marked in the bitmap for concurrent marking to discover. 3960 if (collector_state()->in_initial_mark_gc()) { 3961 oop pll_head = Universe::reference_pending_list(); 3962 if (pll_head != NULL) { 3963 // Any valid worker id is fine here as we are in the VM thread and single-threaded. 3964 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head); 3965 } 3966 } 3967 3968 // FIXME 3969 // CM's reference processing also cleans up the string and symbol tables. 3970 // Should we do that here also? We could, but it is a serial operation 3971 // and could significantly increase the pause time. 3972 3973 double ref_enq_time = os::elapsedTime() - ref_enq_start; 3974 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0); 3975 } 3976 3977 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) { 3978 double merge_pss_time_start = os::elapsedTime(); 3979 per_thread_states->flush(); 3980 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0); 3981 } 3982 3983 void G1CollectedHeap::pre_evacuate_collection_set() { 3984 _expand_heap_after_alloc_failure = true; 3985 _evacuation_failed = false; 3986 3987 // Disable the hot card cache. 3988 _hot_card_cache->reset_hot_cache_claimed_index(); 3989 _hot_card_cache->set_use_cache(false); 3990 3991 g1_rem_set()->prepare_for_oops_into_collection_set_do(); 3992 _preserved_marks_set.assert_empty(); 3993 3994 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 3995 3996 // InitialMark needs claim bits to keep track of the marked-through CLDs. 3997 if (collector_state()->in_initial_mark_gc()) { 3998 double start_clear_claimed_marks = os::elapsedTime(); 3999 4000 ClassLoaderDataGraph::clear_claimed_marks(); 4001 4002 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0; 4003 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms); 4004 } 4005 } 4006 4007 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) { 4008 // Should G1EvacuationFailureALot be in effect for this GC? 4009 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();) 4010 4011 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty"); 4012 4013 G1GCPhaseTimes* phase_times = g1_policy()->phase_times(); 4014 4015 double start_par_time_sec = os::elapsedTime(); 4016 double end_par_time_sec; 4017 4018 { 4019 const uint n_workers = workers()->active_workers(); 4020 G1RootProcessor root_processor(this, n_workers); 4021 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers); 4022 4023 print_termination_stats_hdr(); 4024 4025 workers()->run_task(&g1_par_task); 4026 end_par_time_sec = os::elapsedTime(); 4027 4028 // Closing the inner scope will execute the destructor 4029 // for the G1RootProcessor object. We record the current 4030 // elapsed time before closing the scope so that time 4031 // taken for the destructor is NOT included in the 4032 // reported parallel time. 4033 } 4034 4035 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0; 4036 phase_times->record_par_time(par_time_ms); 4037 4038 double code_root_fixup_time_ms = 4039 (os::elapsedTime() - end_par_time_sec) * 1000.0; 4040 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms); 4041 } 4042 4043 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) { 4044 // Also cleans the card table from temporary duplicate detection information used 4045 // during UpdateRS/ScanRS. 4046 g1_rem_set()->cleanup_after_oops_into_collection_set_do(); 4047 4048 // Process any discovered reference objects - we have 4049 // to do this _before_ we retire the GC alloc regions 4050 // as we may have to copy some 'reachable' referent 4051 // objects (and their reachable sub-graphs) that were 4052 // not copied during the pause. 4053 process_discovered_references(per_thread_states); 4054 enqueue_discovered_references(per_thread_states); 4055 4056 G1STWIsAliveClosure is_alive(this); 4057 G1KeepAliveClosure keep_alive(this); 4058 4059 { 4060 double start = os::elapsedTime(); 4061 4062 WeakProcessor::weak_oops_do(&is_alive, &keep_alive); 4063 4064 double time_ms = (os::elapsedTime() - start) * 1000.0; 4065 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms); 4066 } 4067 4068 if (G1StringDedup::is_enabled()) { 4069 double fixup_start = os::elapsedTime(); 4070 4071 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times()); 4072 4073 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; 4074 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); 4075 } 4076 4077 if (evacuation_failed()) { 4078 restore_after_evac_failure(); 4079 4080 // Reset the G1EvacuationFailureALot counters and flags 4081 // Note: the values are reset only when an actual 4082 // evacuation failure occurs. 4083 NOT_PRODUCT(reset_evacuation_should_fail();) 4084 } 4085 4086 _preserved_marks_set.assert_empty(); 4087 4088 _allocator->release_gc_alloc_regions(evacuation_info); 4089 4090 merge_per_thread_state_info(per_thread_states); 4091 4092 // Reset and re-enable the hot card cache. 4093 // Note the counts for the cards in the regions in the 4094 // collection set are reset when the collection set is freed. 4095 _hot_card_cache->reset_hot_cache(); 4096 _hot_card_cache->set_use_cache(true); 4097 4098 purge_code_root_memory(); 4099 4100 redirty_logged_cards(); 4101 #if COMPILER2_OR_JVMCI 4102 double start = os::elapsedTime(); 4103 DerivedPointerTable::update_pointers(); 4104 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0); 4105 #endif 4106 g1_policy()->print_age_table(); 4107 } 4108 4109 void G1CollectedHeap::record_obj_copy_mem_stats() { 4110 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize); 4111 4112 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats), 4113 create_g1_evac_summary(&_old_evac_stats)); 4114 } 4115 4116 void G1CollectedHeap::free_region(HeapRegion* hr, 4117 FreeRegionList* free_list, 4118 bool skip_remset, 4119 bool skip_hot_card_cache, 4120 bool locked) { 4121 assert(!hr->is_free(), "the region should not be free"); 4122 assert(!hr->is_empty(), "the region should not be empty"); 4123 assert(_hrm.is_available(hr->hrm_index()), "region should be committed"); 4124 assert(free_list != NULL, "pre-condition"); 4125 4126 if (G1VerifyBitmaps) { 4127 MemRegion mr(hr->bottom(), hr->end()); 4128 concurrent_mark()->clear_range_in_prev_bitmap(mr); 4129 } 4130 4131 // Clear the card counts for this region. 4132 // Note: we only need to do this if the region is not young 4133 // (since we don't refine cards in young regions). 4134 if (!skip_hot_card_cache && !hr->is_young()) { 4135 _hot_card_cache->reset_card_counts(hr); 4136 } 4137 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */); 4138 _g1_policy->remset_tracker()->update_at_free(hr); 4139 free_list->add_ordered(hr); 4140 } 4141 4142 void G1CollectedHeap::free_humongous_region(HeapRegion* hr, 4143 FreeRegionList* free_list) { 4144 assert(hr->is_humongous(), "this is only for humongous regions"); 4145 assert(free_list != NULL, "pre-condition"); 4146 hr->clear_humongous(); 4147 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */); 4148 } 4149 4150 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed, 4151 const uint humongous_regions_removed) { 4152 if (old_regions_removed > 0 || humongous_regions_removed > 0) { 4153 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4154 _old_set.bulk_remove(old_regions_removed); 4155 _humongous_set.bulk_remove(humongous_regions_removed); 4156 } 4157 4158 } 4159 4160 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) { 4161 assert(list != NULL, "list can't be null"); 4162 if (!list->is_empty()) { 4163 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag); 4164 _hrm.insert_list_into_free_list(list); 4165 } 4166 } 4167 4168 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) { 4169 decrease_used(bytes); 4170 } 4171 4172 class G1FreeCollectionSetTask : public AbstractGangTask { 4173 private: 4174 4175 // Closure applied to all regions in the collection set to do work that needs to 4176 // be done serially in a single thread. 4177 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure { 4178 private: 4179 EvacuationInfo* _evacuation_info; 4180 const size_t* _surviving_young_words; 4181 4182 // Bytes used in successfully evacuated regions before the evacuation. 4183 size_t _before_used_bytes; 4184 // Bytes used in unsucessfully evacuated regions before the evacuation 4185 size_t _after_used_bytes; 4186 4187 size_t _bytes_allocated_in_old_since_last_gc; 4188 4189 size_t _failure_used_words; 4190 size_t _failure_waste_words; 4191 4192 FreeRegionList _local_free_list; 4193 public: 4194 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4195 HeapRegionClosure(), 4196 _evacuation_info(evacuation_info), 4197 _surviving_young_words(surviving_young_words), 4198 _before_used_bytes(0), 4199 _after_used_bytes(0), 4200 _bytes_allocated_in_old_since_last_gc(0), 4201 _failure_used_words(0), 4202 _failure_waste_words(0), 4203 _local_free_list("Local Region List for CSet Freeing") { 4204 } 4205 4206 virtual bool do_heap_region(HeapRegion* r) { 4207 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4208 4209 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index()); 4210 g1h->clear_in_cset(r); 4211 4212 if (r->is_young()) { 4213 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(), 4214 "Young index %d is wrong for region %u of type %s with %u young regions", 4215 r->young_index_in_cset(), 4216 r->hrm_index(), 4217 r->get_type_str(), 4218 g1h->collection_set()->young_region_length()); 4219 size_t words_survived = _surviving_young_words[r->young_index_in_cset()]; 4220 r->record_surv_words_in_group(words_survived); 4221 } 4222 4223 if (!r->evacuation_failed()) { 4224 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index()); 4225 _before_used_bytes += r->used(); 4226 g1h->free_region(r, 4227 &_local_free_list, 4228 true, /* skip_remset */ 4229 true, /* skip_hot_card_cache */ 4230 true /* locked */); 4231 } else { 4232 r->uninstall_surv_rate_group(); 4233 r->set_young_index_in_cset(-1); 4234 r->set_evacuation_failed(false); 4235 // When moving a young gen region to old gen, we "allocate" that whole region 4236 // there. This is in addition to any already evacuated objects. Notify the 4237 // policy about that. 4238 // Old gen regions do not cause an additional allocation: both the objects 4239 // still in the region and the ones already moved are accounted for elsewhere. 4240 if (r->is_young()) { 4241 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes; 4242 } 4243 // The region is now considered to be old. 4244 r->set_old(); 4245 // Do some allocation statistics accounting. Regions that failed evacuation 4246 // are always made old, so there is no need to update anything in the young 4247 // gen statistics, but we need to update old gen statistics. 4248 size_t used_words = r->marked_bytes() / HeapWordSize; 4249 4250 _failure_used_words += used_words; 4251 _failure_waste_words += HeapRegion::GrainWords - used_words; 4252 4253 g1h->old_set_add(r); 4254 _after_used_bytes += r->used(); 4255 } 4256 return false; 4257 } 4258 4259 void complete_work() { 4260 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4261 4262 _evacuation_info->set_regions_freed(_local_free_list.length()); 4263 _evacuation_info->increment_collectionset_used_after(_after_used_bytes); 4264 4265 g1h->prepend_to_freelist(&_local_free_list); 4266 g1h->decrement_summary_bytes(_before_used_bytes); 4267 4268 G1Policy* policy = g1h->g1_policy(); 4269 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc); 4270 4271 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words); 4272 } 4273 }; 4274 4275 G1CollectionSet* _collection_set; 4276 G1SerialFreeCollectionSetClosure _cl; 4277 const size_t* _surviving_young_words; 4278 4279 size_t _rs_lengths; 4280 4281 volatile jint _serial_work_claim; 4282 4283 struct WorkItem { 4284 uint region_idx; 4285 bool is_young; 4286 bool evacuation_failed; 4287 4288 WorkItem(HeapRegion* r) { 4289 region_idx = r->hrm_index(); 4290 is_young = r->is_young(); 4291 evacuation_failed = r->evacuation_failed(); 4292 } 4293 }; 4294 4295 volatile size_t _parallel_work_claim; 4296 size_t _num_work_items; 4297 WorkItem* _work_items; 4298 4299 void do_serial_work() { 4300 // Need to grab the lock to be allowed to modify the old region list. 4301 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag); 4302 _collection_set->iterate(&_cl); 4303 } 4304 4305 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) { 4306 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4307 4308 HeapRegion* r = g1h->region_at(region_idx); 4309 assert(!g1h->is_on_master_free_list(r), "sanity"); 4310 4311 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths); 4312 4313 if (!is_young) { 4314 g1h->_hot_card_cache->reset_card_counts(r); 4315 } 4316 4317 if (!evacuation_failed) { 4318 r->rem_set()->clear_locked(); 4319 } 4320 } 4321 4322 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure { 4323 private: 4324 size_t _cur_idx; 4325 WorkItem* _work_items; 4326 public: 4327 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { } 4328 4329 virtual bool do_heap_region(HeapRegion* r) { 4330 _work_items[_cur_idx++] = WorkItem(r); 4331 return false; 4332 } 4333 }; 4334 4335 void prepare_work() { 4336 G1PrepareFreeCollectionSetClosure cl(_work_items); 4337 _collection_set->iterate(&cl); 4338 } 4339 4340 void complete_work() { 4341 _cl.complete_work(); 4342 4343 G1Policy* policy = G1CollectedHeap::heap()->g1_policy(); 4344 policy->record_max_rs_lengths(_rs_lengths); 4345 policy->cset_regions_freed(); 4346 } 4347 public: 4348 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) : 4349 AbstractGangTask("G1 Free Collection Set"), 4350 _cl(evacuation_info, surviving_young_words), 4351 _collection_set(collection_set), 4352 _surviving_young_words(surviving_young_words), 4353 _serial_work_claim(0), 4354 _rs_lengths(0), 4355 _parallel_work_claim(0), 4356 _num_work_items(collection_set->region_length()), 4357 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) { 4358 prepare_work(); 4359 } 4360 4361 ~G1FreeCollectionSetTask() { 4362 complete_work(); 4363 FREE_C_HEAP_ARRAY(WorkItem, _work_items); 4364 } 4365 4366 // Chunk size for work distribution. The chosen value has been determined experimentally 4367 // to be a good tradeoff between overhead and achievable parallelism. 4368 static uint chunk_size() { return 32; } 4369 4370 virtual void work(uint worker_id) { 4371 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times(); 4372 4373 // Claim serial work. 4374 if (_serial_work_claim == 0) { 4375 jint value = Atomic::add(1, &_serial_work_claim) - 1; 4376 if (value == 0) { 4377 double serial_time = os::elapsedTime(); 4378 do_serial_work(); 4379 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0); 4380 } 4381 } 4382 4383 // Start parallel work. 4384 double young_time = 0.0; 4385 bool has_young_time = false; 4386 double non_young_time = 0.0; 4387 bool has_non_young_time = false; 4388 4389 while (true) { 4390 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim); 4391 size_t cur = end - chunk_size(); 4392 4393 if (cur >= _num_work_items) { 4394 break; 4395 } 4396 4397 double start_time = os::elapsedTime(); 4398 4399 end = MIN2(end, _num_work_items); 4400 4401 for (; cur < end; cur++) { 4402 bool is_young = _work_items[cur].is_young; 4403 4404 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed); 4405 4406 double end_time = os::elapsedTime(); 4407 double time_taken = end_time - start_time; 4408 if (is_young) { 4409 young_time += time_taken; 4410 has_young_time = true; 4411 } else { 4412 non_young_time += time_taken; 4413 has_non_young_time = true; 4414 } 4415 start_time = end_time; 4416 } 4417 } 4418 4419 if (has_young_time) { 4420 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time); 4421 } 4422 if (has_non_young_time) { 4423 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time); 4424 } 4425 } 4426 }; 4427 4428 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) { 4429 _eden.clear(); 4430 4431 double free_cset_start_time = os::elapsedTime(); 4432 4433 { 4434 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U); 4435 uint const num_workers = MIN2(workers()->active_workers(), num_chunks); 4436 4437 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words); 4438 4439 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u", 4440 cl.name(), 4441 num_workers, 4442 _collection_set.region_length()); 4443 workers()->run_task(&cl, num_workers); 4444 } 4445 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0); 4446 4447 collection_set->clear(); 4448 } 4449 4450 class G1FreeHumongousRegionClosure : public HeapRegionClosure { 4451 private: 4452 FreeRegionList* _free_region_list; 4453 HeapRegionSet* _proxy_set; 4454 uint _humongous_objects_reclaimed; 4455 uint _humongous_regions_reclaimed; 4456 size_t _freed_bytes; 4457 public: 4458 4459 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) : 4460 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) { 4461 } 4462 4463 virtual bool do_heap_region(HeapRegion* r) { 4464 if (!r->is_starts_humongous()) { 4465 return false; 4466 } 4467 4468 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 4469 4470 oop obj = (oop)r->bottom(); 4471 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap(); 4472 4473 // The following checks whether the humongous object is live are sufficient. 4474 // The main additional check (in addition to having a reference from the roots 4475 // or the young gen) is whether the humongous object has a remembered set entry. 4476 // 4477 // A humongous object cannot be live if there is no remembered set for it 4478 // because: 4479 // - there can be no references from within humongous starts regions referencing 4480 // the object because we never allocate other objects into them. 4481 // (I.e. there are no intra-region references that may be missed by the 4482 // remembered set) 4483 // - as soon there is a remembered set entry to the humongous starts region 4484 // (i.e. it has "escaped" to an old object) this remembered set entry will stay 4485 // until the end of a concurrent mark. 4486 // 4487 // It is not required to check whether the object has been found dead by marking 4488 // or not, in fact it would prevent reclamation within a concurrent cycle, as 4489 // all objects allocated during that time are considered live. 4490 // SATB marking is even more conservative than the remembered set. 4491 // So if at this point in the collection there is no remembered set entry, 4492 // nobody has a reference to it. 4493 // At the start of collection we flush all refinement logs, and remembered sets 4494 // are completely up-to-date wrt to references to the humongous object. 4495 // 4496 // Other implementation considerations: 4497 // - never consider object arrays at this time because they would pose 4498 // considerable effort for cleaning up the the remembered sets. This is 4499 // required because stale remembered sets might reference locations that 4500 // are currently allocated into. 4501 uint region_idx = r->hrm_index(); 4502 if (!g1h->is_humongous_reclaim_candidate(region_idx) || 4503 !r->rem_set()->is_empty()) { 4504 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", 4505 region_idx, 4506 (size_t)obj->size() * HeapWordSize, 4507 p2i(r->bottom()), 4508 r->rem_set()->occupied(), 4509 r->rem_set()->strong_code_roots_list_length(), 4510 next_bitmap->is_marked(r->bottom()), 4511 g1h->is_humongous_reclaim_candidate(region_idx), 4512 obj->is_typeArray() 4513 ); 4514 return false; 4515 } 4516 4517 guarantee(obj->is_typeArray(), 4518 "Only eagerly reclaiming type arrays is supported, but the object " 4519 PTR_FORMAT " is not.", p2i(r->bottom())); 4520 4521 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", 4522 region_idx, 4523 (size_t)obj->size() * HeapWordSize, 4524 p2i(r->bottom()), 4525 r->rem_set()->occupied(), 4526 r->rem_set()->strong_code_roots_list_length(), 4527 next_bitmap->is_marked(r->bottom()), 4528 g1h->is_humongous_reclaim_candidate(region_idx), 4529 obj->is_typeArray() 4530 ); 4531 4532 G1ConcurrentMark* const cm = g1h->concurrent_mark(); 4533 cm->humongous_object_eagerly_reclaimed(r); 4534 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj), 4535 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s", 4536 region_idx, 4537 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)), 4538 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj))); 4539 _humongous_objects_reclaimed++; 4540 do { 4541 HeapRegion* next = g1h->next_region_in_humongous(r); 4542 _freed_bytes += r->used(); 4543 r->set_containing_set(NULL); 4544 _humongous_regions_reclaimed++; 4545 g1h->free_humongous_region(r, _free_region_list); 4546 r = next; 4547 } while (r != NULL); 4548 4549 return false; 4550 } 4551 4552 uint humongous_objects_reclaimed() { 4553 return _humongous_objects_reclaimed; 4554 } 4555 4556 uint humongous_regions_reclaimed() { 4557 return _humongous_regions_reclaimed; 4558 } 4559 4560 size_t bytes_freed() const { 4561 return _freed_bytes; 4562 } 4563 }; 4564 4565 void G1CollectedHeap::eagerly_reclaim_humongous_regions() { 4566 assert_at_safepoint_on_vm_thread(); 4567 4568 if (!G1EagerReclaimHumongousObjects || 4569 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) { 4570 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0); 4571 return; 4572 } 4573 4574 double start_time = os::elapsedTime(); 4575 4576 FreeRegionList local_cleanup_list("Local Humongous Cleanup List"); 4577 4578 G1FreeHumongousRegionClosure cl(&local_cleanup_list); 4579 heap_region_iterate(&cl); 4580 4581 remove_from_old_sets(0, cl.humongous_regions_reclaimed()); 4582 4583 G1HRPrinter* hrp = hr_printer(); 4584 if (hrp->is_active()) { 4585 FreeRegionListIterator iter(&local_cleanup_list); 4586 while (iter.more_available()) { 4587 HeapRegion* hr = iter.get_next(); 4588 hrp->cleanup(hr); 4589 } 4590 } 4591 4592 prepend_to_freelist(&local_cleanup_list); 4593 decrement_summary_bytes(cl.bytes_freed()); 4594 4595 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0, 4596 cl.humongous_objects_reclaimed()); 4597 } 4598 4599 class G1AbandonCollectionSetClosure : public HeapRegionClosure { 4600 public: 4601 virtual bool do_heap_region(HeapRegion* r) { 4602 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index()); 4603 G1CollectedHeap::heap()->clear_in_cset(r); 4604 r->set_young_index_in_cset(-1); 4605 return false; 4606 } 4607 }; 4608 4609 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) { 4610 G1AbandonCollectionSetClosure cl; 4611 collection_set->iterate(&cl); 4612 4613 collection_set->clear(); 4614 collection_set->stop_incremental_building(); 4615 } 4616 4617 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) { 4618 return _allocator->is_retained_old_region(hr); 4619 } 4620 4621 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) { 4622 _eden.add(hr); 4623 _g1_policy->set_region_eden(hr); 4624 } 4625 4626 #ifdef ASSERT 4627 4628 class NoYoungRegionsClosure: public HeapRegionClosure { 4629 private: 4630 bool _success; 4631 public: 4632 NoYoungRegionsClosure() : _success(true) { } 4633 bool do_heap_region(HeapRegion* r) { 4634 if (r->is_young()) { 4635 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young", 4636 p2i(r->bottom()), p2i(r->end())); 4637 _success = false; 4638 } 4639 return false; 4640 } 4641 bool success() { return _success; } 4642 }; 4643 4644 bool G1CollectedHeap::check_young_list_empty() { 4645 bool ret = (young_regions_count() == 0); 4646 4647 NoYoungRegionsClosure closure; 4648 heap_region_iterate(&closure); 4649 ret = ret && closure.success(); 4650 4651 return ret; 4652 } 4653 4654 #endif // ASSERT 4655 4656 class TearDownRegionSetsClosure : public HeapRegionClosure { 4657 private: 4658 HeapRegionSet *_old_set; 4659 4660 public: 4661 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { } 4662 4663 bool do_heap_region(HeapRegion* r) { 4664 if (r->is_old()) { 4665 _old_set->remove(r); 4666 } else if(r->is_young()) { 4667 r->uninstall_surv_rate_group(); 4668 } else { 4669 // We ignore free regions, we'll empty the free list afterwards. 4670 // We ignore humongous regions, we're not tearing down the 4671 // humongous regions set. 4672 assert(r->is_free() || r->is_humongous(), 4673 "it cannot be another type"); 4674 } 4675 return false; 4676 } 4677 4678 ~TearDownRegionSetsClosure() { 4679 assert(_old_set->is_empty(), "post-condition"); 4680 } 4681 }; 4682 4683 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) { 4684 assert_at_safepoint_on_vm_thread(); 4685 4686 if (!free_list_only) { 4687 TearDownRegionSetsClosure cl(&_old_set); 4688 heap_region_iterate(&cl); 4689 4690 // Note that emptying the _young_list is postponed and instead done as 4691 // the first step when rebuilding the regions sets again. The reason for 4692 // this is that during a full GC string deduplication needs to know if 4693 // a collected region was young or old when the full GC was initiated. 4694 } 4695 _hrm.remove_all_free_regions(); 4696 } 4697 4698 void G1CollectedHeap::increase_used(size_t bytes) { 4699 _summary_bytes_used += bytes; 4700 } 4701 4702 void G1CollectedHeap::decrease_used(size_t bytes) { 4703 assert(_summary_bytes_used >= bytes, 4704 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT, 4705 _summary_bytes_used, bytes); 4706 _summary_bytes_used -= bytes; 4707 } 4708 4709 void G1CollectedHeap::set_used(size_t bytes) { 4710 _summary_bytes_used = bytes; 4711 } 4712 4713 class RebuildRegionSetsClosure : public HeapRegionClosure { 4714 private: 4715 bool _free_list_only; 4716 HeapRegionSet* _old_set; 4717 HeapRegionManager* _hrm; 4718 size_t _total_used; 4719 4720 public: 4721 RebuildRegionSetsClosure(bool free_list_only, 4722 HeapRegionSet* old_set, HeapRegionManager* hrm) : 4723 _free_list_only(free_list_only), 4724 _old_set(old_set), _hrm(hrm), _total_used(0) { 4725 assert(_hrm->num_free_regions() == 0, "pre-condition"); 4726 if (!free_list_only) { 4727 assert(_old_set->is_empty(), "pre-condition"); 4728 } 4729 } 4730 4731 bool do_heap_region(HeapRegion* r) { 4732 // After full GC, no region should have a remembered set. 4733 r->rem_set()->clear(true); 4734 if (r->is_empty()) { 4735 // Add free regions to the free list 4736 r->set_free(); 4737 _hrm->insert_into_free_list(r); 4738 } else if (!_free_list_only) { 4739 4740 if (r->is_humongous()) { 4741 // We ignore humongous regions. We left the humongous set unchanged. 4742 } else { 4743 assert(r->is_young() || r->is_free() || r->is_old(), "invariant"); 4744 // We now move all (non-humongous, non-old) regions to old gen, and register them as such. 4745 r->move_to_old(); 4746 _old_set->add(r); 4747 } 4748 _total_used += r->used(); 4749 } 4750 4751 return false; 4752 } 4753 4754 size_t total_used() { 4755 return _total_used; 4756 } 4757 }; 4758 4759 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) { 4760 assert_at_safepoint_on_vm_thread(); 4761 4762 if (!free_list_only) { 4763 _eden.clear(); 4764 _survivor.clear(); 4765 } 4766 4767 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm); 4768 heap_region_iterate(&cl); 4769 4770 if (!free_list_only) { 4771 set_used(cl.total_used()); 4772 if (_archive_allocator != NULL) { 4773 _archive_allocator->clear_used(); 4774 } 4775 } 4776 assert(used_unlocked() == recalculate_used(), 4777 "inconsistent used_unlocked(), " 4778 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT, 4779 used_unlocked(), recalculate_used()); 4780 } 4781 4782 bool G1CollectedHeap::is_in_closed_subset(const void* p) const { 4783 HeapRegion* hr = heap_region_containing(p); 4784 return hr->is_in(p); 4785 } 4786 4787 // Methods for the mutator alloc region 4788 4789 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size, 4790 bool force) { 4791 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4792 bool should_allocate = g1_policy()->should_allocate_mutator_region(); 4793 if (force || should_allocate) { 4794 HeapRegion* new_alloc_region = new_region(word_size, 4795 false /* is_old */, 4796 false /* do_expand */); 4797 if (new_alloc_region != NULL) { 4798 set_region_short_lived_locked(new_alloc_region); 4799 _hr_printer.alloc(new_alloc_region, !should_allocate); 4800 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region); 4801 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4802 return new_alloc_region; 4803 } 4804 } 4805 return NULL; 4806 } 4807 4808 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region, 4809 size_t allocated_bytes) { 4810 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */); 4811 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden"); 4812 4813 collection_set()->add_eden_region(alloc_region); 4814 increase_used(allocated_bytes); 4815 _hr_printer.retire(alloc_region); 4816 // We update the eden sizes here, when the region is retired, 4817 // instead of when it's allocated, since this is the point that its 4818 // used space has been recored in _summary_bytes_used. 4819 g1mm()->update_eden_size(); 4820 } 4821 4822 // Methods for the GC alloc regions 4823 4824 bool G1CollectedHeap::has_more_regions(InCSetState dest) { 4825 if (dest.is_old()) { 4826 return true; 4827 } else { 4828 return survivor_regions_count() < g1_policy()->max_survivor_regions(); 4829 } 4830 } 4831 4832 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) { 4833 assert(FreeList_lock->owned_by_self(), "pre-condition"); 4834 4835 if (!has_more_regions(dest)) { 4836 return NULL; 4837 } 4838 4839 const bool is_survivor = dest.is_young(); 4840 4841 HeapRegion* new_alloc_region = new_region(word_size, 4842 !is_survivor, 4843 true /* do_expand */); 4844 if (new_alloc_region != NULL) { 4845 if (is_survivor) { 4846 new_alloc_region->set_survivor(); 4847 _survivor.add(new_alloc_region); 4848 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region); 4849 } else { 4850 new_alloc_region->set_old(); 4851 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region); 4852 } 4853 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region); 4854 _hr_printer.alloc(new_alloc_region); 4855 bool during_im = collector_state()->in_initial_mark_gc(); 4856 new_alloc_region->note_start_of_copying(during_im); 4857 return new_alloc_region; 4858 } 4859 return NULL; 4860 } 4861 4862 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region, 4863 size_t allocated_bytes, 4864 InCSetState dest) { 4865 bool during_im = collector_state()->in_initial_mark_gc(); 4866 alloc_region->note_end_of_copying(during_im); 4867 g1_policy()->record_bytes_copied_during_gc(allocated_bytes); 4868 if (dest.is_old()) { 4869 _old_set.add(alloc_region); 4870 } 4871 _hr_printer.retire(alloc_region); 4872 } 4873 4874 HeapRegion* G1CollectedHeap::alloc_highest_free_region() { 4875 bool expanded = false; 4876 uint index = _hrm.find_highest_free(&expanded); 4877 4878 if (index != G1_NO_HRM_INDEX) { 4879 if (expanded) { 4880 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B", 4881 HeapRegion::GrainWords * HeapWordSize); 4882 } 4883 _hrm.allocate_free_regions_starting_at(index, 1); 4884 return region_at(index); 4885 } 4886 return NULL; 4887 } 4888 4889 // Optimized nmethod scanning 4890 4891 class RegisterNMethodOopClosure: public OopClosure { 4892 G1CollectedHeap* _g1h; 4893 nmethod* _nm; 4894 4895 template <class T> void do_oop_work(T* p) { 4896 T heap_oop = RawAccess<>::oop_load(p); 4897 if (!CompressedOops::is_null(heap_oop)) { 4898 oop obj = CompressedOops::decode_not_null(heap_oop); 4899 HeapRegion* hr = _g1h->heap_region_containing(obj); 4900 assert(!hr->is_continues_humongous(), 4901 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4902 " starting at " HR_FORMAT, 4903 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4904 4905 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries. 4906 hr->add_strong_code_root_locked(_nm); 4907 } 4908 } 4909 4910 public: 4911 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4912 _g1h(g1h), _nm(nm) {} 4913 4914 void do_oop(oop* p) { do_oop_work(p); } 4915 void do_oop(narrowOop* p) { do_oop_work(p); } 4916 }; 4917 4918 class UnregisterNMethodOopClosure: public OopClosure { 4919 G1CollectedHeap* _g1h; 4920 nmethod* _nm; 4921 4922 template <class T> void do_oop_work(T* p) { 4923 T heap_oop = RawAccess<>::oop_load(p); 4924 if (!CompressedOops::is_null(heap_oop)) { 4925 oop obj = CompressedOops::decode_not_null(heap_oop); 4926 HeapRegion* hr = _g1h->heap_region_containing(obj); 4927 assert(!hr->is_continues_humongous(), 4928 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT 4929 " starting at " HR_FORMAT, 4930 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())); 4931 4932 hr->remove_strong_code_root(_nm); 4933 } 4934 } 4935 4936 public: 4937 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) : 4938 _g1h(g1h), _nm(nm) {} 4939 4940 void do_oop(oop* p) { do_oop_work(p); } 4941 void do_oop(narrowOop* p) { do_oop_work(p); } 4942 }; 4943 4944 // Returns true if the reference points to an object that 4945 // can move in an incremental collection. 4946 bool G1CollectedHeap::is_scavengable(oop obj) { 4947 HeapRegion* hr = heap_region_containing(obj); 4948 return !hr->is_pinned(); 4949 } 4950 4951 void G1CollectedHeap::register_nmethod(nmethod* nm) { 4952 guarantee(nm != NULL, "sanity"); 4953 RegisterNMethodOopClosure reg_cl(this, nm); 4954 nm->oops_do(®_cl); 4955 } 4956 4957 void G1CollectedHeap::unregister_nmethod(nmethod* nm) { 4958 guarantee(nm != NULL, "sanity"); 4959 UnregisterNMethodOopClosure reg_cl(this, nm); 4960 nm->oops_do(®_cl, true); 4961 } 4962 4963 void G1CollectedHeap::purge_code_root_memory() { 4964 double purge_start = os::elapsedTime(); 4965 G1CodeRootSet::purge(); 4966 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0; 4967 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms); 4968 } 4969 4970 class RebuildStrongCodeRootClosure: public CodeBlobClosure { 4971 G1CollectedHeap* _g1h; 4972 4973 public: 4974 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) : 4975 _g1h(g1h) {} 4976 4977 void do_code_blob(CodeBlob* cb) { 4978 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL; 4979 if (nm == NULL) { 4980 return; 4981 } 4982 4983 if (ScavengeRootsInCode) { 4984 _g1h->register_nmethod(nm); 4985 } 4986 } 4987 }; 4988 4989 void G1CollectedHeap::rebuild_strong_code_roots() { 4990 RebuildStrongCodeRootClosure blob_cl(this); 4991 CodeCache::blobs_do(&blob_cl); 4992 } 4993 4994 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() { 4995 GrowableArray<GCMemoryManager*> memory_managers(2); 4996 memory_managers.append(&_memory_manager); 4997 memory_managers.append(&_full_gc_memory_manager); 4998 return memory_managers; 4999 } 5000 5001 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() { 5002 GrowableArray<MemoryPool*> memory_pools(3); 5003 memory_pools.append(_eden_pool); 5004 memory_pools.append(_survivor_pool); 5005 memory_pools.append(_old_pool); 5006 return memory_pools; 5007 }